WorldWideScience

Sample records for oligocene epoch

  1. Oligocene tectonics and sedimentation, California

    Science.gov (United States)

    Nilsen, T.H.

    1984-01-01

    During the Oligocene epoch, California was marked by extensive nonmarine sedimentation, in contrast to its pre-Oligocene and post-Oligocene depositional history. The Oligocene continental deposits are especially widespread in southern California and fill a number of small and generally partly restricted basins. Fluvial facies in many basins prograded over previously deposited lower Tertiary turbidites. Volcanism, from widespread centers, was associated with the nonmarine sedimentation. However, some basins remained marine and a few contain Oligocene turbidites and pelagic sediments deposited at bathyal depths. The Oligocene redbeds of California do not form a post-orogenic molasse sequence comparable to the Old Red Sandstone or Alpine molasse. They are synorogenic and record local uplift of basins and surrounding source areas. Late Cretaceous to contemporary orogenesis in California has been generally characterized by the formation of small restricted basins of variable depth adjacent to small upland areas in response to strike-slip faulting. Deposition of Oligocene redbeds was associated with climatic change from warm and humid to cold and semiarid, and a global lowering of sea level. Oligocene tectonism occurred during the transition from subduction of the Farallon Plate to initiation of the modern San Andreas transform system. However, the major influence that caused uplift, formation of fault-bounded basins, and extensive redbed deposition, especially in southern California, was the approach of the Pacific-Farallon spreading ridge to the western margin of California. ?? 1984.

  2. The Terrestrial Eocene-Oligocene Transition in North America

    Science.gov (United States)

    Prothero, Donald R.; Emry, Robert J.

    1996-06-01

    The transition from the Eocene to the Oligocene epoch, occurring approximately 47 to 30 million years ago, was the most dramatic episode of climatic and biotic change since the demise of the dinosaurs. The mild tropical climates of the Paleocene and early Eocene were replaced by modern climatic conditions and extremes, including glacial ice in Antarctica. The first part of this book summarizes the latest information in the dating and correlation of the strata of late middle Eocene through early Oligocene age in North America. The second part reviews almost all the important terrestrial reptiles and mammals found near the Eocene-Oligocene boundary, in the White River Chronofauna--from the turtles, snakes and lizards to the common rodents, carnivores, oreodonts and deer of the Badlands. This is the first comprehensive treatment of these topics in over sixty years, and will be invaluable to vertebrate paleontologists, geologists, mammalogists and evolutionary biologists.

  3. Fossil dolphin Otekaikea marplesi (latest Oligocene, New Zealand) expands the morphological and taxonomic diversity of Oligocene cetaceans.

    Science.gov (United States)

    Tanaka, Yoshihiro; Fordyce, R Ewan

    2014-01-01

    The Oligocene Epoch was a time of major radiation of the Odontoceti (echolocating toothed whales, dolphins). Fossils reveal many odontocete lineages and considerable structural diversity, but whether the clades include some crown taxa or only archaic groups is contentious. The New Zealand fossil dolphin "Prosqualodon" marplesi (latest Oligocene, ≥23.9 Ma) is here identified as a crown odontocete that represents a new genus, Otekaikea, and adds to the generic diversity of Oligocene odontocetes. Otekaikea marplesi is known only from the holotype, which comprises a partial skeleton from the marine Otekaike Limestone of the Waitaki Valley. Otekaikea marplesi was about 2.5 m long; it had procumbent anterior teeth, and a broad dished face for the nasofacial muscles implicated in production of echolocation sounds. The prominent condyles and unfused cervical vertebrae suggest a flexible neck. A phylogenetic analysis based on morphological features places Otekaikea marplesi in the extinct group Waipatiidae, within the clade Platanistoidea. The phylogeny implies an Oligocene origin for the lineage now represented by the endangered Ganges River dolphin (Platanista gangetica), supporting an Oligocene history for the crown Odontoceti.

  4. The epoch of reionization

    Science.gov (United States)

    Benson, Andrew J.; Sugiyama, Naoshi; Nusser, Adi; Lacey, Cedric G.

    2006-07-01

    We have modelled the process of reionization of the intergalactic medium (IGM) by photoionization by galaxies, in order to learn what galaxy formation in the framework of the cold dark matter (CDM) model predicts for the epoch of reionization. We use a sophisticated semi-analytic model of galaxy formation to track the formation of these galaxies, their influence on the IGM and the back reaction of the state of the IGM on further galaxy formation. Our study represents a much more complete and physically consistent modelling of reionization than has been conducted in the past. In particular, compared to previous work by ourselves and others, our new calculations contain significant improvements in the modelling of the effects of reionization of the IGM on the collapse of baryons into dark matter haloes (this is now computed self-consistently from the properties of model galaxies), and in the model for the cooling and condensation of gas within haloes (our new model includes photoheating from a self-consistently computed ionizing background and also includes cooling due to molecular hydrogen). We find that reionization can be achieved by z ~ 10-20 in a ΛCDM cosmological model with σ8 ~ 0.9. However, a cosmological model with a running spectral index is only able to achieve reionization before z ~ 9, and thus be consistent with an optical depth of 0.1, if very extreme assumptions are made about the physics of feedback at high redshifts. We also consider the specific galaxy formation model recently discussed by Baugh et al., which includes a top-heavy initial mass function (IMF) in starbursts, and find that it is able to reionize the Universe by z ~ 12. The previous results assume that all of the ionizing photons produced by stars in galaxies are able to escape and ionize the IGM. If this is not the case, then the redshift of reionization could be substantially reduced. We find that extended periods of partial reionization and double reionizations can occur in models

  5. The quantum epoché.

    Science.gov (United States)

    Pylkkänen, Paavo

    2015-12-01

    The theme of phenomenology and quantum physics is here tackled by examining some basic interpretational issues in quantum physics. One key issue in quantum theory from the very beginning has been whether it is possible to provide a quantum ontology of particles in motion in the same way as in classical physics, or whether we are restricted to stay within a more limited view of quantum systems, in terms of complementary but mutually exclusive phenomena. In phenomenological terms we could describe the situation by saying that according to the usual interpretation of quantum theory (especially Niels Bohr's), quantum phenomena require a kind of epoché (i.e. a suspension of assumptions about reality at the quantum level). However, there are other interpretations (especially David Bohm's) that seem to re-establish the possibility of a mind-independent ontology at the quantum level. We will show that even such ontological interpretations contain novel, non-classical features, which require them to give a special role to "phenomena" or "appearances", a role not encountered in classical physics. We will conclude that while ontological interpretations of quantum theory are possible, quantum theory implies the need of a certain kind of epoché even for this type of interpretations. While different from the epoché connected to phenomenological description, the "quantum epoché" nevertheless points to a potentially interesting parallel between phenomenology and quantum philosophy. Copyright © 2015. Published by Elsevier Ltd.

  6. Strong near-epoch dependence

    Institute of Scientific and Technical Information of China (English)

    LIN Zhengyan

    2004-01-01

    We introduce a new class of dependent sequences of random variables, which is a subclass of near-epoch dependent sequences, but can also be approximated by mixing sequences. For this kind of sequences of random variables, we call them strong nearepoch dependent sequences, a p-order, p > 2, (maximum) moment inequality is established under weaker dependence sizes.

  7. Dynamics of the Oligocene Southern Ocean: dinocysts as surface paleoceanographic tracers

    Science.gov (United States)

    Bijl, Peter; Houben, Alexander; Brinkhuis, Henk; Sangiorgi, Francesca

    2015-04-01

    The Oligocene Epoch (33.9-23 Ma) is the time interval in the Cenozoic that saw the establishment of a continental-scale Antarctic ice-sheet. There remains a controversy about whether this early episode of a glaciated Antarctica was stable, or whether dynamic ice conditions prevailed. Most of this controversy persists due to the absence of chronostratigraphically well-dated sedimentary archives from close to the east Antarctic ice sheet, which has recorded a direct signal of glacial dynamics. Another major question is how the Oligocene Southern Ocean responded to the glaciation and subsequent evolution of the ice sheet, as the Southern ocean is a major player in global ocean circulation. Numerical modelling studies suggest that alongside the buildup of continental ice on Antarctica, first sea-ice conditions may have started along the East Antarctic Margin, but this conclusion lacks support from field evidence. Other numerical models predict that hysteresis effects within the ice sheet will make a continental-size Antarctic ice sheet rather insensitive to warming. In contrast, deep-water benthic foraminiferal oxygen isotope records across the Oligocene suggest dramatic waxing and waning of Antarctic ice sheets. This paradox is as yet not solved Integrated Ocean Drilling Expedition 318 drilled the Antarctic Margin in 2010, and recovered sediments from the early phase of Antarctic glaciation. With this record, we can now evaluate the robustness of the results of the numerical models and the oceanographic changes with field data. Sediments recovered from Site U1356 yield a thick and relatively complete (albeit compromised by core gaps) Oligocene succession both of which are chrono-stratigraphically well-calibrated with use of nannoplankton- dinocyst- and magnetostratigraphy. Notably, this record yields well-preserved dinoflagellate cysts (dinocysts), which we can use to investigate surface-water condition changes across the Eocene-Oligocene to provide answers to these

  8. Dinoflagellate cyst biostratigraphy and age of the Oligocene Momijiyama formation, Yubari Coal-Field, central Hokkaido, Japan; Hokkaido yubari tanden chiiki, zenshinto momijiyamaso no kaben moso kasekisojo to nendai

    Energy Technology Data Exchange (ETDEWEB)

    Kurita, H.; Miwa, M. [Japan Petroleum Exploration Co. Ltd., Chiba (Japan). JAPEX Research Center

    1998-01-15

    The Momijiyama formation distributed in the Yubari coalfield region of Hokkaido is one of the typical sea Oligocenes in the northern Japan. However, there has been much argument about the age of the Momijiyama formation. This paper reports newly-obtained findings concerning the upper limit age of the Momijiyama formation determined by the analysis of a dinoflagellate fossil, an organic microfossil, conducting a fission track (FT) age determination, and putting together the results of the analysis and determination and the results of the analysis of dinoflagellate fossil reported by Kurita and Matsuoka (1994). It can currently be concluded on the basis of both the data on the dinoflagellate cyst biostratigraphy which were obtained in the Hobetsu region and those on the radioactive data that the upper limit age of the Momijiyama formation is an initial period of the Oligocene epoch. The age of the floating foraminifer and the calcareous nannofossil produced from the upper portion of the Horonai formation, a formation on the lower layer of the Momijiyama formation is the final period of the Eocene or the initial period of the Oligocene. Therefore, it is considered that the lower limit age of the Momijiyama formation is substantially before or after the transition from the Eocene epoch to the Oligocene epoch. 19 refs., 4 figs., 1 tab.

  9. Epoch-based analysis of speech signals

    Indian Academy of Sciences (India)

    B Yegnanarayana; Suryakanth V Gangashetty

    2011-10-01

    Speech analysis is traditionally performed using short-time analysis to extract features in time and frequency domains. The window size for the analysis is fixed somewhat arbitrarily, mainly to account for the time varying vocal tract system during production. However, speech in its primary mode of excitation is produced due to impulse-like excitation in each glottal cycle. Anchoring the speech analysis around the glottal closure instants (epochs) yields significant benefits for speech analysis. Epoch-based analysis of speech helps not only to segment the speech signals based on speech production characteristics, but also helps in accurate analysis of speech. It enables extraction of important acoustic-phonetic features such as glottal vibrations, formants, instantaneous fundamental frequency, etc. Epoch sequence is useful to manipulate prosody in speech synthesis applications. Accurate estimation of epochs helps in characterizing voice quality features. Epoch extraction also helps in speech enhancement and multispeaker separation. In this tutorial article, the importance of epochs for speech analysis is discussed, and methods to extract the epoch information are reviewed. Applications of epoch extraction for some speech applications are demonstrated.

  10. The epochs of international law

    CERN Document Server

    Grewe, Wilhelm G

    2000-01-01

    A theoretical overview and detailed analysis of the history of international law from the Middle Ages through to the end of the twentieth century (updated from the 1984 German language edition). Wilhelm Grewe's "Epochen der Völkerrechtsgeschichte" is widely regarded as one of the classic twentieth century works of international law. This revised translation by Michael Byers of Oxford University makes this important book available to non-German readers for the first time. "The Epochs of International Law" provides a theoretical overview and detailed analysis of the history of international law from the Middle Ages, to the Age of Discovery and the Thirty Years War, from Napoleon Bonaparte to the Treaty of Versailles and the Age of the Single Superpower, and does so in a way that reflects Grewe's own experience as one of Germany's leading diplomats and professors of international law. A new chapter, written by Wilhelm Grewe and Michael Byers, updates the book to 1998, making the revised translation of interest ...

  11. Deep-water Oligocene pollen record from South China Sea

    Institute of Scientific and Technical Information of China (English)

    WU Guoxuan; QIN Jungan; MAO Shaozhi

    2003-01-01

    Leg 184 of ODP recovered a record of deep- water sediments spanning the past 32.8 Ma from the South China Sea (SCS). The sediments of the Oligocene (32.8 - 23.8 Ma) at Site 1148 contain relatively abundant fossil pollen. The pollen analysis at Site 1148 has established the first pollen assemblage sequence of deep-water Oligocene in the China Sea. The pollen assemblages of the Oligocene are dominated by montane conifer tree pollen. The abundances of broad-leaved tree pollen are lower in the assemblages. Both of the montane conifer and broad-leaved tree pollen groups include mainly tropical-subtropical components. The pollen of cold and drought-enduring plants is present in lower content. The distinct change in pollen assemblage sequence of deep-water Oligocene of the SCS occurred at 32.0 Ma, indicative of an important shift of the Oligocene climate in the SCS region. The characteristics of the pollen flora of the deep-water Oligocene indicate the tropical montane rainforest and lowland rainforest developed on the areas around the SCS before 32.0 Ma, reflecting the warm and wet climatic condition. In the pollen flora of the Oligocene after 32.0 Ma, the temperate montane conifer and cool and drought-en- during deciduous tree taxa remarkably increased, indicating that the climate in the SCS region became comparatively cool and dry.

  12. Synchronization Phenomena and Epoch Filter of Electroencephalogram

    Science.gov (United States)

    Matani, Ayumu

    Nonlinear electrophysiological synchronization phenomena in the brain, such as event-related (de)synchronization, long distance synchronization, and phase-reset, have received much attention in neuroscience over the last decade. These phenomena contain more electrical than physiological keywords and actually require electrical techniques to capture with electroencephalography (EEG). For instance, epoch filters, which have just recently been proposed, allow us to investigate such phenomena. Moreover, epoch filters are still developing and would hopefully generate a new paradigm in neuroscience from an electrical engineering viewpoint. Consequently, electrical engineers could be interested in EEG once again or from now on.

  13. LEDDB: LOFAR Epoch of Reionization Diagnostic Database

    NARCIS (Netherlands)

    Martinez-Rubi, O.; Veligatla, V. K.; de Bruyn, A. G.; Lampropoulos, P.; Offringa, A. R.; Jelic, V.; Yatawatta, S.; Koopmans, L. V. E.; Zaroubi, S.

    2013-01-01

    One of the key science projects of the Low-Frequency Array (LOFAR) is the detection of the cosmological signal coming from the Epoch of Reionization (EoR). Here we present the LOFAR EoR Diagnostic Database (LEDDB) that is used in the storage, management, processing and analysis of the LOFAR EoR obse

  14. LEDDB : LOFAR Epoch of Reionization Diagnostic Database

    NARCIS (Netherlands)

    Martinez-Rubi, O.; Veligatla, V. K.; de Bruyn, A. G.; Lampropoulos, P.; Offringa, A. R.; Jelic, V.; Yatawatta, S.; Koopmans, L. V. E.; Zaroubi, S.; Friedel, D. N.

    2013-01-01

    One of the key science projects of the Low-Frequency Array (LOFAR) is the detection of the cosmological signal coming from the Epoch of Reionization (EoR). Here we present the LOFAR EoR Diagnostic Database (LEDDB) that is used in the storage, management, processing and analysis of the LOFAR EoR obse

  15. Oligocene crustal anatexis in the Tethyan Himalaya, southern Tibet

    Science.gov (United States)

    Gao, Li-E.; Zeng, Lingsen; Gao, Jiahao; Shang, Zhen; Hou, Kejun; Wang, Qian

    2016-11-01

    Recent studies in the Xiaru and Malashan gneiss dome of the Tethyan Himalaya, southern Tibet identify that Xiaru and Paiku tourmaline-bearing leucogranite dike formed at 28-29 Ma. Together with 28 Ma Kuday garnet-bearing leucogranites, it is demonstrated that the Himalayan orogenic belt experienced a major episode of crustal melting in the Mid-Oligocene. Geochemical data indicate that three suites of leucogranite are characterized by large variations in the major and trace element compositions as well as Sr-Nd isotope systematics, which could be explained by combined fractional crystallization and relative contributions of micas and accessory phases dissolved into a crustal melt during decompressional melting of metapelitic rocks. Documentation of Oligocene partial melting of crustal rocks could indicate that the exhumation of deep crustal rocks in the Himalayan orogenic belt could have started as early as Oligocene.

  16. Oligocene calibration of the magnetic polarity time scale

    Science.gov (United States)

    Prothero, Donald R.; Denham, Charles R.; Farmer, Harlow G.

    1982-12-01

    Magnetostratigraphic studies of the Oligocene White River Group in Wyoming, Colorado, Nebraska, and the Dakotas yield a radiometrically dated polarity stratigraphy that provides mid-Tertiary calibration points for the magnetic polarity time scale. Anomaly 12 13 reversal is bracketed by dates of 32.4 and 34.6 m.y., in best agreement with the time scale of LaBrecque and colleagues. The magnetostratigraphy also helps calibrate the Oligocene North American land mammal “ages” and allows correlation with the European marine microfossil zonation. This correlation suggests that the age of the Eocene-Oligocene boundary is 37.0 m.y., contrary to younger dates obtained from glauconites and microtektites. *Present address: Department of Geology, Knox College, Galesburg, Illinois 61401

  17. Hydrogen Epoch of Reionization Array (HERA)

    CERN Document Server

    DeBoer, David R; Aguirre, James E; Alexander, Paul; Ali, Zaki S; Beardsley, Adam P; Bernardi, Gianni; Bowman, Judd D; Bradley, Richard F; Carilli, Chris L; Cheng, Carina; Acedo, Eloy de Lera; Dillon, Joshua S; Ewall-Wice, Aaron; Fadana, Gcobisa; Fagnoni, Nicolas; Fritz, Randall; Furlanetto, Steve R; Glendenning, Brian; Greig, Bradley; Grobbelaar, Jasper; Hazelton, Bryna J; Hewitt, Jacqueline N; Hickish, Jack; Jacobs, Daniel C; Julius, Austin; Kariseb, MacCalvin; Kohn, Saul A; Lekalake, Telalo; Liu, Adrian; Loots, Anita; MacMahon, David; Malan, Lourence; Malgas, Cresshim; Maree, Matthys; Mathison, Nathan; Matsetela, Eunice; Mesinger, Andrei; Morales, Miguel F; Neben, Abraham R; Patra, Nipanjana; Pieterse, Samantha; Pober, Jonathan C; Razavi-Ghods, Nima; Ringuette, Jon; Robnett, James; Rosie, Kathryn; Sell, Raddwine; Smith, Craig; Syce, Angelo; Tegmark, Max; Thyagarajan, Nithyanandan; Williams, Peter K G; Zheng, Haoxuan

    2016-01-01

    The Hydrogen Epoch of Reionization Array (HERA) is a staged experiment to measure 21 cm emission from the primordial intergalactic medium (IGM) throughout cosmic reionization ($z=6-12$), and to explore earlier epochs of our Cosmic Dawn ($z\\sim30$). During these epochs, early stars and black holes heated and ionized the IGM, introducing fluctuations in 21 cm emission. HERA is designed to characterize the evolution of the 21 cm power spectrum to constrain the timing and morphology of reionization, the properties of the first galaxies, the evolution of large-scale structure, and the early sources of heating. The full HERA instrument will be a 350-element interferometer in South Africa consisting of 14-m parabolic dishes observing from 50 to 250 MHz. Currently, 19 dishes have been deployed on site and the next 18 are under construction. HERA has been designated as an SKA Precursor instrument. In this paper, we summarize HERA's scientific context and provide forecasts for its key science results. After reviewing t...

  18. Climate response to orbital forcing across the Oligocene-Miocene boundary.

    Science.gov (United States)

    Zachos, J C; Shackleton, N J; Revenaugh, J S; Pälike, H; Flower, B P

    2001-04-13

    Spectral analyses of an uninterrupted 5.5-million-year (My)-long chronology of late Oligocene-early Miocene climate and ocean carbon chemistry from two deep-sea cores recovered in the western equatorial Atlantic reveal variance concentrated at all Milankovitch frequencies. Exceptional spectral power in climate is recorded at the 406-thousand-year (ky) period eccentricity band over a 3.4-million-year period [20 to 23.4 My ago (Ma)] as well as in the 125- and 95-ky bands over a 1.3-million-year period (21.7 to 23.0 Ma) of suspected low greenhouse gas levels. Moreover, a major transient glaciation at the epoch boundary ( approximately 23 Ma), Mi-1, corresponds with a rare orbital congruence involving obliquity and eccentricity. The anomaly, which consists of low-amplitude variance in obliquity (a node) and a minimum in eccentricity, results in an extended period ( approximately 200 ky) of low seasonality orbits favorable to ice-sheet expansion on Antarctica.

  19. Lower Oligocene bivalves of Ramanian Stage from Kachchh, Gujarat, India

    Science.gov (United States)

    Kachhara, R. P.; Jodhawat, R. L.; Devi, K. Bigyapati

    2012-04-01

    Marine Oligocene sequences in India outcrop only in western part of Kachchh. Earlier researchers have recognized the Oligocene strata under the Nari Series (Nagappa 1959; Chatterji and Mathur 1966). The Nari Series has a type area in Pakistan. It has two subdivisions - the Lower Nari (Lower Oligocene) and the Upper Nari (Upper Oligocene). It seems that there is no valid proof about the age of the Lower Nari due to lack of proper fauna (Eames 1975), and according to Pascoe (1962), the Upper Nari slightly transgress into Aquitanian (Lower Miocene), therefore, one has to be very cautious. Biswas and Raju (1971) reclassified the Oligocene strata of Kachchh and lithostratigraphically clubbed them as the Maniyara Fort Formation with type section along the Bermoti stream. This Formation has four members. The lower three members correspond to the Ramanian Stage (Lower Oligocene, Biswas 1971, 1973) while the uppermost to the Waiorian Stage (Upper Oligocene, Biswas 1965, 1971, 1973). The Ramanian Stage is characterized by large forams especially Nummulites fichteli, Nummulites fichteli intermedius, Lepidocyclina ( Eulepidina) dialata and Operculina sp. Several ostracods are also known to occur. Megafauna include bivalves, gastropods, echinoids, corals, mammals and reptiles. Concerning bivalves earlier researchers have recorded a few taxa namely Trisidos semitorta (Lamarck), Cubitostrea angulata (J de C Sowerby), Pecten ( Amussiopecten) labadyei d'Archiac and Haime, Periglypta puerpera (Linne') var. aglaurae Brongniart, Ostrea fraasi Mayer Eymer and listed Pecten laevicostatus J de C Sowerby, Callista pseudoumbonella Vredenburg and Clementia papyracea (Gray) from Kachchh as against overall 42 forms from the Nari Series as a whole (Vredenburg 1928). This tempted us to make an attempt to collect bivalve fauna systematically which are occurring prolifically in the Ramanian Stage. In the present work, for this purpose, sections are worked out around Lakhpat (23°50'N; 68°47'E

  20. Lower Oligocene bivalves of Ramanian Stage from Kachchh, Gujarat, India

    Indian Academy of Sciences (India)

    R P Kachhara; R L Jodhawat; K Bigyapati Devi

    2012-04-01

    Marine Oligocene sequences in India outcrop only in western part of Kachchh. Earlier researchers have recognized the Oligocene strata under the Nari Series (Nagappa 1959; Chatterji and Mathur 1966). The Nari Series has a type area in Pakistan. It has two subdivisions – the Lower Nari (Lower Oligocene) and the Upper Nari (Upper Oligocene). It seems that there is no valid proof about the age of the Lower Nari due to lack of proper fauna (Eames 1975), and according to Pascoe (1962), the Upper Nari slightly transgress into Aquitanian (Lower Miocene), therefore, one has to be very cautious. Biswas and Raju (1971) reclassified the Oligocene strata of Kachchh and lithostratigraphically clubbed them as the Maniyara Fort Formation with type section along the Bermoti stream. This Formation has four members. The lower three members correspond to the Ramanian Stage (Lower Oligocene, Biswas 1971, 1973) while the uppermost to the Waiorian Stage (Upper Oligocene, Biswas 1965, 1971, 1973). The Ramanian Stage is characterized by large forams especially Nummulites fichteli, Nummulites fichteli intermedius, Lepidocyclina (Eulepidina) dialata and Operculina sp. Several ostracods are also known to occur. Megafauna include bivalves, gastropods, echinoids, corals, mammals and reptiles. Concerning bivalves earlier researchers have recorded a few taxa namely Trisidos semitorta (Lamarck), Cubitostrea angulata (J de C Sowerby), Pecten (Amussiopecten) labadyei d’Archiac and Haime, Periglypta puerpera (Linne’) var. aglaurae Brongniart, Ostrea fraasi Mayer Eymer and listed Pecten laevicostatus J de C Sowerby, Callista pseudoumbonella Vredenburg and Clementia papyracea (Gray) from Kachchh as against overall 42 forms from the Nari Series as a whole (Vredenburg 1928). This tempted us to make an attempt to collect bivalve fauna systematically which are occurring prolifically in the Ramanian Stage. In the present work, for this purpose, sections are worked out around Lakhpat (23° 50′N; 68

  1. Administering an epoch initiated for remote memory access

    Science.gov (United States)

    Blocksome, Michael A.; Miller, Douglas R.

    2013-01-01

    Methods, systems, and products are disclosed for administering an epoch initiated for remote memory access that include: initiating, by an origin application messaging module on an origin compute node, one or more data transfers to a target compute node for the epoch; initiating, by the origin application messaging module after initiating the data transfers, a closing stage for the epoch, including rejecting any new data transfers after initiating the closing stage for the epoch; determining, by the origin application messaging module, whether the data transfers have completed; and closing, by the origin application messaging module, the epoch if the data transfers have completed.

  2. Hydrogen Epoch of Reionization Array (HERA)

    Science.gov (United States)

    DeBoer, David R.; Parsons, Aaron R.; Aguirre, James E.; Alexander, Paul; Ali, Zaki S.; Beardsley, Adam P.; Bernardi, Gianni; Bowman, Judd D.; Bradley, Richard F.; Carilli, Chris L.; Cheng, Carina; de Lera Acedo, Eloy; Dillon, Joshua S.; Ewall-Wice, Aaron; Fadana, Gcobisa; Fagnoni, Nicolas; Fritz, Randall; Furlanetto, Steve R.; Glendenning, Brian; Greig, Bradley; Grobbelaar, Jasper; Hazelton, Bryna J.; Hewitt, Jacqueline N.; Hickish, Jack; Jacobs, Daniel C.; Julius, Austin; Kariseb, MacCalvin; Kohn, Saul A.; Lekalake, Telalo; Liu, Adrian; Loots, Anita; MacMahon, David; Malan, Lourence; Malgas, Cresshim; Maree, Matthys; Martinot, Zachary; Mathison, Nathan; Matsetela, Eunice; Mesinger, Andrei; Morales, Miguel F.; Neben, Abraham R.; Patra, Nipanjana; Pieterse, Samantha; Pober, Jonathan C.; Razavi-Ghods, Nima; Ringuette, Jon; Robnett, James; Rosie, Kathryn; Sell, Raddwine; Smith, Craig; Syce, Angelo; Tegmark, Max; Thyagarajan, Nithyanandan; Williams, Peter K. G.; Zheng, Haoxuan

    2017-04-01

    The Hydrogen Epoch of Reionization Array (HERA) is a staged experiment to measure 21 cm emission from the primordial intergalactic medium (IGM) throughout cosmic reionization (z = 6-12), and to explore earlier epochs of our Cosmic Dawn (z ˜ 30). During these epochs, early stars and black holes heated and ionized the IGM, introducing fluctuations in 21 cm emission. HERA is designed to characterize the evolution of the 21 cm power spectrum to constrain the timing and morphology of reionization, the properties of the first galaxies, the evolution of large-scale structure, and the early sources of heating. The full HERA instrument will be a 350-element interferometer in South Africa consisting of 14 m parabolic dishes observing from 50 to 250 MHz. Currently, 19 dishes have been deployed on site and the next 18 are under construction. HERA has been designated as an SKA Precursor instrument. In this paper, we summarize HERA’s scientific context and provide forecasts for its key science results. After reviewing the current state of the art in foreground mitigation, we use the delay-spectrum technique to motivate high-level performance requirements for the HERA instrument. Next, we present the HERA instrument design, along with the subsystem specifications that ensure that HERA meets its performance requirements. Finally, we summarize the schedule and status of the project. We conclude by suggesting that, given the realities of foreground contamination, current-generation 21 cm instruments are approaching their sensitivity limits. HERA is designed to bring both the sensitivity and the precision to deliver its primary science on the basis of proven foreground filtering techniques, while developing new subtraction techniques to unlock new capabilities. The result will be a major step toward realizing the widely recognized scientific potential of 21 cm cosmology.

  3. A semi-aquatic Arctic mammalian carnivore from the Miocene epoch and origin of Pinnipedia.

    Science.gov (United States)

    Rybczynski, Natalia; Dawson, Mary R; Tedford, Richard H

    2009-04-23

    Modern pinnipeds (seals, sea lions and the walrus) are semi-aquatic, generally marine carnivores the limbs of which have been modified into flippers. Recent phylogenetic studies using morphological and molecular evidence support pinniped monophyly, and suggest a sister relationship with ursoids (for example bears) or musteloids (the clade that includes skunks, badgers, weasels and otters). Although the position of pinnipeds within modern carnivores appears moderately well resolved, fossil evidence of the morphological steps leading from a terrestrial ancestor to the modern marine forms has been weak or contentious. The earliest well-represented fossil pinniped is Enaliarctos, a marine form with flippers, which had appeared on the northwestern shores of North America by the early Miocene epoch. Here we report the discovery of a nearly complete skeleton of a new semi-aquatic carnivore from an early Miocene lake deposit in Nunavut, Canada, that represents a morphological link in early pinniped evolution. The new taxon retains a long tail and the proportions of its fore- and hindlimbs are more similar to those of modern terrestrial carnivores than to modern pinnipeds. Morphological traits indicative of semi-aquatic adaptation include a forelimb with a prominent deltopectoral ridge on the humerus, a posterodorsally expanded scapula, a pelvis with relatively short ilium, a shortened femur and flattened phalanges, suggestive of webbing. The new fossil shows evidence of pinniped affinities and similarities to the early Oligocene Amphicticeps from Asia and the late Oligocene and Miocene Potamotherium from Europe. The discovery suggests that the evolution of pinnipeds included a freshwater transitional phase, and may support the hypothesis that the Arctic was an early centre of pinniped evolution.

  4. Possible observations of the epoch of reionization

    Science.gov (United States)

    Doroshkevich, A. G.; Pilipenko, S. V.

    2011-07-01

    We consider possibilities for presently operating and planned infrared, submillimeter, and millimeter telescopes for observations of the epoch of reionization in the Universe, i.e., of the sources of ultraviolet radiation that have caused the reionization (galaxies, quasars, etc.) and the ionized intergalactic medium. Along with direct observations of such sources in the optical and infrared, we analyze the feasibility of observations of the intergalactic gas, as well as fluctuations of the temperature and polarization of the cosmic microwave background due to inhomogeneities in the reionization process.

  5. Molecular hydrogen in the cosmic recombination epoch

    CERN Document Server

    Alizadeh, Esfandiar

    2010-01-01

    The advent of precise measurements of the cosmic microwave background (CMB) anisotropies has motivated correspondingly precise calculations of the cosmic recombination history. Cosmic recombination proceeds far out of equilibrium because of a "bottleneck" at the $n=2$ level of hydrogen: atoms can only reach the ground state via slow processes: two-photon decay or Lyman-$\\alpha$ resonance escape. However, even a small primordial abundance of molecules could have a large effect on the interline opacity in the recombination epoch and lead to an additional route for hydrogen recombination. Therefore, this paper computes the abundance of the H$_2$ molecule during the cosmic recombination epoch. Hydrogen molecules in the ground electronic levels X$^1\\Sigma^+_g$ can either form from the excited H$_2$ electronic levels B$^1\\Sigma^+_u$ and C$^1\\Pi_u$ or through the charged particles H$_2^+$, HeH$^+$ and H$^-$. We follow the transitions among all of these species, resolving the rotational and vibrational sub-levels. Si...

  6. Zirconium-titanium placers of the Voronezh Anteclise: Types, epochs and factors of formation, and forecast

    Science.gov (United States)

    Savko, A. D.; Zvonarev, A. E.; Ivanov, D. A.

    2012-02-01

    The early and late Frasnian, Barremian-Aptian, Cenomanian, early Santonian, early Campanian, and Oligocene-Miocene epochs of the formation of various types of zirconium-titanium placers are distinguished in the Voronezh Anteclise. The factors of their formation are considered, and a forecast of prospecting has been made. Lower Frasnian sedimentary rocks occur in the southeast, where the placers are related to the ilmenite-bearing volcanosedimentary rocks of the Yastrebovo Sequence. The upper Frasnian productive quartz sand of the Petino Sequence occurs in the central part of the Voronezh Anteclise. The Barremian-Aptian productive quartz sand and kaolinite clay occur in the northern and northeastern parts of the anteclise (Ryazan and Lipetsk oblasts). The placers formed in the Cenomanian are known in the Tambov oblast in the northeast of the Voronezh Anteclise and are related to phosphate-bearing glauconite-quartz sand. The early Campanian phosphorite-glauconite-quartz formation is widespread in the northwest of the Voronezh Anteclise at the junction with the northeastern wall of the Dnieper-Donets Basin (Bryansk oblast). The Oligocene-Miocene epoch was characterized by quartz sands abundant in the northwestern and south-western areas. The formation of zirconium-titanium placers is controlled by structural-tectonic, facies, volcanic, paleogeographic, stratigraphic, and evolutional factors. The indispensable condition for heavy mineral concentration is existence of positive forms of underwater topography. These are mostly structural elements of the third and fourth orders on the slopes of the Voronezh Anteclise at the boundaries of the adjacent negative structures. As concerns the facies factor, the occurrence of coastal and shallow-water marine facies with alternating and medium hydrodynamic activity and predominance of sand fractions 0.25-0.05 mm are criteria of elevated concentration of heavy minerals in sand. One of the conditions providing concentration of heavy

  7. New insights on the Marseille-Aubagne Oligocene basins (France)

    Energy Technology Data Exchange (ETDEWEB)

    Nury, D.; Villenueve, M.; Azrithac, P.; Gartner, A.; Linneann, U.; Chateauneuf, J. J.

    2016-10-01

    The Marseille-Aubagne Basins, which extend from Marseille to Roquevaire, occupy more than fifty per cent of the Marseille-Aubagne geological map, with approximately one million people living in this area. Despite this geological importance they are still poorly known. The first synthetic view was delivered in the 1935 geological map. Studied by Bonifay, the Quaternary deposits have been included in the 1969 geological map. Nevertheless, the Oligocene formations remained unmodified until Nury, who provided a lot of very detailed stratigraphic data. New studies have been carried out in the frame of the third issue of the 1:50,000 geological map. These studies allow us to distinguish between three different basins: the ''Jarret basin'' in the northern part, the ''Prado basin'' in the southwestern part and the ''Aubagne basin'' in the eastern part. Each of them contains its own stratigraphic succession, including several formations from the Rupelian to the Chattian. Globally, the Lower to Upper Rupelian formations are tectonically deformed, whilst deposits from the Latest Rupelian to the Latest Chattian show only slight deformation. Thus, two main geodynamic stages have been distinguished: the first beginning with the Early Oligocene extensive regime leading to the opening of NNE-SSW troughs all over the European platform and, the second, beginning with a NNW-SSE extensive regime coeval with the Western Mediterranean rifting. The key point that separates these two stages from each other is a possible Late Rupelian compressive regime. To sum up, this basin can be considered as a natural archive for the Oligocene events. Therefore, these basins should be considered as master pieces for the Oligocene palaeogeographic and geodynamic reconstructions. (Author)

  8. Hydrogen Epoch of Reionization Array (HERA)

    Science.gov (United States)

    DeBoer, David R.; HERA

    2015-01-01

    The Hydrogen Epoch of Reionization Arrays (HERA - reionization.org) roadmap uses the unique properties of the neutral hydrogen (HI) 21cm line to probe our cosmic dawn: from the birth of the first stars and black holes, through the full reionization of the primordial intergalactic medium (IGM). HERA is a collaboration between the Precision Array Probing the Epoch of Reionization (PAPER - eor.berkeley.edu), the US-based Murchison Widefield Array (MWA - mwatelescope.org), and MIT Epoch of Reionization (MITEOR) teams along with the South African SKA-SA, University of KwaZulu Natal and the University of Cambridge Cavendish Laborabory. HERA has recently been awarded a National Science Foundation Mid-Scale Innovation Program grant to begin the next phase.HERA leverages the operation of the PAPER and MWA telescopes to explore techniques and designs required to detect the primordial HI signal in the presence of systematics and radio continuum foreground emission some four orders of magnitude brighter. With this understanding, we are now able to remove foregrounds to the limits of our sensitivity, culminating in the first physically meaningful upper limits. A redundant calibration algorithm from MITEOR improves the sensitivity of the approach.Building on this, the next stage of HERA incorporates a 14m diameter antenna element that is optimized both for sensitivity and for minimizing foreground systematics. Arranging these elements in a compact hexagonal grid yields an array that facilitates calibration, leverages proven foreground removal techniques, and is scalable to large collecting areas. HERA will be located in the radio quiet environment of the SKA site in the Karoo region of South Africa (where PAPER is currently located). It will have a sensitivity close to two orders of magnitude better than PAPER and the MWA to ensure a robust detection. With its sensitivity and broader frequency coverage, HERA can paint an uninterrupted picture through reionization, back to the

  9. Orion: The Final Epoch (OrionTFE)

    Science.gov (United States)

    Megeath, Tom; Allen, Tom; Arce, Hector; Booker, Joseph; Calvet, Nuria; Flaherty, Kevin; Furlan, Elise; Fischer, Will; Gonzales, Beatriz; Gutermuth, Rob; Hartman, Lee; Henning, Thomas; Hora, Joe; Karnath, Nicole; Kim, Kyoung Hee; Kounkel, Marina; Mazur, Brian; Offner, Stella; Osorio, Mayra; Pillitteri, Ignazio; Pipher, Judy; Prchlik, Jakub; Rebull, Luisa; Terebey, Susan; Tobin, John; Stanke, Thomas; Stutz, Amelia; Watson, Dan; Wolk, Scott

    2016-08-01

    The Orion molecular clouds are an essential laboratory for studying low mass star formation over the broad range of environments in which they form. Starting with the Spitzer survey of Orion in 2004, more than a decade of observations with Spitzer, WISE, HST and Herschel, have accumulated an unparalleled characterization of the young stellar object population in Orion. We propose a final epoch of observations divided into two separate, complementary observations: A repeat of the entire Orion molecular cloud survey to 1.) identify ejected stars from clusters, 2.) measure the bulk proper motions of groups and clusters of stars, 3.) constrain the rate of luminous, accretion driven outbursts from both protostars and pre-main sequence stars with disks and 4.) use proper motions of IR Herbig-Haro knots as a fossil record of previous accretion events. A high cadence variability survey of the L1641 cloud extending the YSOVAR variability survey of the Orion Nebula Cluster across the Orion A cloud with the goals of 1.) constraining the star formation history of Orion A, 2.) studying the evolution of mid-IR variability from the protostellar to pre-main sequence phase, 3.) searching for periodicities in (nearly) edge-on protostars and disks due to orbiting clumps and structures from orbiting planets, and 4.) assessing whether inner disk processes - as traced by variability - are affected by their birth environment. This program completes an unparalleled, > 12 year multi-epoch, mid-IR study of the nearest large molecular cloud complex with both a wide spatial coverage and a uniformity that will not be exceeded in the forseeable future. It will place unique constraints on the highly dynamic processes that control low mass star formation, serve as a pathfinder to molecular cloud surveys of WFIRST, and provide well characterized targets needed to study mass accretion and planet formation around young low mass stars with SOFIA and JWST.

  10. Romanticism as epoch : an investigation into the possibility of epochal categorization

    OpenAIRE

    Theil, Marius

    2003-01-01

    Sammendrag: Part one is a critical discussion of two methodical presuppositions that underlie most theories of the Romantic epoch in the twentieth century: nominal Romanticism and the classical theory of categorisation. Nominal Romanticism is a principle of selection which delegates romanticity to things that are called Romantic, that is, conventionally associated with it. The rationale for this principle is that persons have a higher claim to romanticity than products or ideas, and t...

  11. Oligocene-Miocene Transition in the North Atlantic Interrupted by Warming: New Records from the Newfoundland Margin, IODP Expedition 342

    Science.gov (United States)

    Smith, R.; Liebrand, D.; van Peer, T. E.; Bohaty, S. M.; Friedrich, O.; Bornemann, A.; Blum, P.; Wilson, P. A.

    2016-12-01

    The beginning and end of the Oligocene epoch were marked by major Antarctic glaciation events. While the Eocene-Oligocene transition is known to have initiated sustained major ice sheets on Antarctica, the intensification of glaciation associated with the Oligocene-Miocene Transition (OMT) 23 Ma appears to have been ephemeral. The inference of rapid growth and then retreat of large Antarctic ice sheets on orbital time scales is difficult to reconcile with the strong hysteresis seen in the results of numerical ice sheet model experiments and the modest variability seen in published records of atmospheric CO2. A number of benthic foraminiferal proxy records have been generated at orbital resolution across the OMT, but high-resolution sea-surface records are sparse, particularly in the mid to high latitudes of the northern hemisphere, with none yet produced in the Atlantic Ocean. IODP Site 1406 (40°N, 3799 m water depth, Expedition 342: Newfoundland Sediment Drifts) recovered an interval spanning the OMT in the North Atlantic. We present planktic foraminiferal stable isotope data from this interval (23.5-22.5 Ma) with an average sample spacing of 2 kyrs. Our high-fidelity sea surface record benefits from exceptional `glassy' preservation of clay-hosted foraminifera. Variability in our record shows prominent 100 kyr eccentricity pacing (cycle amplitude typically >1.0 ‰ in δ18O and >0.6‰ in δ13C) and a strong precessional influence. Intriguingly, while the rise in δ18O associated with the OMT is fairly smooth in benthic records, our planktic data show that after over two-thirds of the total 1.6‰ rise in δ18O had already taken place, a 50 kyr recovery to pre-OMT δ18O values occured, preceeding a rapid transition to the OMT δ18O maximum. Our results demonstrate for the first time the North Atlantic sea surface response to OMT events. The structure in our new planktic stable isotope record differs markedly from that seen in published benthic records

  12. Ultracool Dwarf Science from Widefield Multi-Epoch Surveys

    CERN Document Server

    Deacon, N R; Lucas, P W; Liu, Michael C; Bessell, M S; Burningham, B; Cushing, M C; Day-Jones, A C; Dhital, S; Law, N M; Mainzer, A K; Zhang, Z H

    2010-01-01

    Widefield surveys have always provided a rich hunting ground for the coolest stars and brown dwarfs. The single epoch surveys at the beginning of this century greatly expanded the parameter space for ultracool dwarfs. Here we outline the science possible from new multi-epoch surveys which add extra depth and open the time domain to study.

  13. The Politics of Religion in instant epoche

    Directory of Open Access Journals (Sweden)

    Jarosław Marzec

    2011-11-01

    Full Text Available In presented text I focused on category of religion in instant culture, in which, as we know everything is fast. This phenomenon dominated also in the sphere of religion by the idiom of obligation of realisation here and now. We all need that right now! How Zbyszko Melosik has written, this phrase express this tendency: “fast food, fast car and fast sex”. But how all that relate to the title politics of religion in instant epoche and what does it include in that optical review? Thus, we can enumerate several characteristic phenomena in wide field of spirituality, but it does not mean simply New Age. I present the politics of religion in the very wide context: from review of J. Mariański’s conception of religion in the postmodern society, to “invisible religion” by Thomas Luckmann, to the implantation of meditation practices in the stream of therapeutic practices in the West by Jon Kabat-Zinn, and in the end to the view of Ken Wilber of “boomeritis buddism”, as the corossion of spirit of buddism in the conemporary american awangarda.

  14. Stellar core collapse. I - Infall epoch

    Science.gov (United States)

    van Riper, K. A.; Lattimer, J. M.

    1981-10-01

    Simulations of the collapse of the central iron core of a 15-solar-mass spherically symmetric star are reported. In this paper the infall epoch, between the onset of collapse and core bounce, is considered. The models use the recent equation of state of Lamb, Lattimer, Pethick, and Ravenhall and general-relativistic hydrodynamics. The electron capture rates on nuclei proceed rapidly for densities less than 10 to the 11th g/cu cm, but are suppressed at higher densities where the neutron number of the nucleus, N, exceeds 40 (Fuller, Fowler, and Newman). Neutrino transport is treated by a leakage scheme. The effects of changes in the neutrino trapping density and of qualitative changes in the electron capture reactions on the evolution are explored. Greater lepton loss during collapse leads to larger pressure deficits, more rapid collapse, and smaller inner homologous cores. The entropy change during the infall is small, the absolute value of delta s being less than 0.8. The mass of inner core is given, to about 20%, by the formula of Goldreich and Weber. Because the collapsing core is far from equilibrium, the effects of general relativity are small.

  15. Lithostratigraphy of the Upper Oligocene - Miocene succession of Denmark

    Directory of Open Access Journals (Sweden)

    Piasecki, Stefan

    2010-12-01

    Full Text Available This paper presents a revised lithostratigraphic scheme for the uppermost Upper Oligocene – Miocene succession of Denmark. The marine Oligocene Brejning Clay Member is upgraded to formation status and includes the Sydklint Member and the Øksenrade Member (new. The shallow marine and deltaic deposits of mainly Early Miocene age are included in the Ribe Group (new while the fully marine Middle and Upper Miocene clay-rich deposits are referred to the Måde Group (new. The Ribe Group is subdivided into 6 formations: the Vejle Fjord Formation is revised and includes the Skansebakke Member,the Billund Formation (new includes the Addit and Hvidbjerg Members (new, the Klintinghoved Formation is redefined formally and includes the Koldingfjord Member (new, the Bastrup Formation(new includes the Resen Member (new, the Vandel Member is a new member in the Arnum Formation (revised, the Odderup Formation is redefined and includes the Stauning Member (new and the coalbearing Fasterholt Member. The Måde Group is subdivided into the Hodde, Ørnhøj (new, Gram and Marbæk (new Formations. Subdivision of the Upper Oligocene – Miocene succession into two groups, the Ribe and Måde Groups, is compatible with the North Sea lithostratigraphic framework where they correlate with the upper part of the Hordaland Group and the Nordland Group, respectively. The revised lithostratigraphic framework correlated in three dimensions provides rigorous constraints on the palaeogeographic interpretation of the Late Oligocene – Miocene period. Three major deltaic units (Billund, Bastrup and Odderup Formations prograded from the north and north-east into the North Sea Basin during the Early – early Middle Miocene. Delta progradation was punctuated by deposition of marine clay and silt associated with minor transgressive events (Vejle Fjord, Klintinghoved and Arnum Formations. During the Middle–Late Miocene, marine depositional conditions dominated (Hodde, Ørnhøj and

  16. Skeletal remains of Propliopithecus chirobates from the Egyptian Oligocene.

    Science.gov (United States)

    Fleagle, J G; Simons, E L

    1982-01-01

    A distal humerus, a fragmentary ulna, a tibia and several partial calcanei from Oligocene sediments in the Fayum Province of Egypt are attributed to Propliopithecus chirobates. Comparison and analysis of this material indicates that this species was an arboreal quadruped. All of the skeletal elements are more similar to the same bones in the Miocene hominoid Pliopithecus vindobonensis than to any extant primate species. Like Pliopithecus and Aegyptopithecus zeuxis, Propliopithecus exhibits numerous primitive skeletal features and more closely resembles living ceboids than either extant hominoids or cercopithecoid monkeys.

  17. The first finding of the crab Ctenocheles (Decapoda in Oligocene beds in Slovenia

    Directory of Open Access Journals (Sweden)

    Vasja Mikuž

    2003-06-01

    Full Text Available In the paper remains of crabs of genus Ctenocheles are discussed. They were found in the Oligocene grey marly mudstone at Čeplje at Vransko. This is the first evidence of this crab genus in Slovenia. In the Oligocene mudstone at ^eplje also numerous other fossilremains were registred, and also abundant septarian concretions.

  18. Two new fossil fruits from Oligocene sediments of Makum Coalfield, Assam, India

    Energy Technology Data Exchange (ETDEWEB)

    Mehrotra, R.C. [Birbal Sahni Institute of Paleobotany, Lucknow (India)

    2000-07-01

    Two new fossil fruits belonging to Sterculia of Sterculiaceae and Barringtonia of Lecythidaceae are described from the Oligocene sediments of Makum Coalfield, Assam, India. These fruits are reported for the first time not only from the Oligocene of Assam but from the Tertiary of India. Their presence supports the view that evergreen to littoral and swamp forests existed there during the time of deposition.

  19. New Insight into the Cosmic Renaissance Epoch

    Science.gov (United States)

    2003-08-01

    VLT Discovers a Group of Early Inhabitants and Find Signs of Many More [1] Summary Using the ESO Very Large Telescope (VLT) , two astronomers from Germany and the UK [2] have discovered some of the most distant galaxies ever seen . They are located about 12,600 million light-years away. It has taken the light now recorded by the VLT about nine-tenths of the age of the Universe to traverse this huge distance. We therefore observe those galaxies as they were at a time when the Universe was very young, less than about 10% of its present age . At this time, the Universe was emerging from a long period known as the "Dark Ages" , entering the luminous "Cosmic Renaissance" epoch. Unlike previous studies which resulted in the discovery of a few, widely dispersed galaxies at this early epoch, the present study found at least six remote citizens within a small sky area, less than five per cent the size of the full moon! This allowed understanding the evolution of these galaxies and how they affect the state of the Universe in its youth. In particular, the astronomers conclude on the basis of their unique data that there were considerably fewer luminous galaxies in the Universe at this early stage than 500 million years later. There must therefore be many less luminous galaxies in the region of space that they studied, too faint to be detected in this study. It must be those still unidentified galaxies that emit the majority of the energetic photons needed to ionise the hydrogen in the Universe at that particularly epoch. PR Photo 25a/03 : Colour-composite of the sky field with the distant galaxies. PR Photo 25b/03 : Close-Up images of some of the most distant galaxies known in the Universe. PR Photo 25c/03 : Spectra of these galaxies. From the Big Bang to the Cosmic Renaissance Nowadays, the Universe is pervaded by energetic ultraviolet radiation, produced by quasars and hot stars. The short-wavelength photons liberate electrons from the hydrogen atoms that make up the

  20. Epoch-dependent absorption line profile variability in lambda Cep

    CERN Document Server

    Uuh-Sonda, J M; Eenens, P; Mahy, L; Palate, M; Gosset, E; Flores, C A

    2014-01-01

    We present the analysis of a multi-epoch spectroscopic monitoring campaign of the O6Ief star lambda Cep. Previous observations reported the existence of two modes of non-radial pulsations in this star. Our data reveal a much more complex situation. The frequency content of the power spectrum considerably changes from one epoch to the other. We find no stable frequency that can unambiguously be attributed to pulsations. The epoch-dependence of the frequencies and variability patterns are similar to what is seen in the wind emission lines of this and other Oef stars, suggesting that both phenomena likely have the same, currently still unknown, origin.

  1. Rotation of the Universe at different cosmological epochs

    Science.gov (United States)

    Chechin, L. M.

    2016-06-01

    A step-by-step foundation for the differential character of the Universe's rotation is presented. First, invoking the concept of spacetime foam with spin, it is reasonable to assume that the very early Universe can be described by the Dirac equation. Second, it is shown using the Ehrenfest theorem that, from a classical point of view, the early Universe can be described by the Papapetrou equations. Third, it is stressed that our Universe can perform only rotational motion. It is shown based on the spin part of the Papapetrou equations that the Universe's rotation depends appreciably on the physical properties of a specific cosmological epoch. The rotational angular velocity is calculated for three basic cosmological epochs: the matter-dominated epoch, the transition period (from domination of matter to domination of vacuum), and the vacuum-dominated epoch.

  2. The Oligocene flora from the Uricani coalfield, Petrosani Basin, Romania

    Science.gov (United States)

    Pirnea, Roxana; Popa, Mihai E.

    2017-04-01

    The Petrosani Basin is a typical Oligocene - Miocene intramontaneous basin located in the South Carpathians. It has a SW-NE orientation and is 48-km long; its width is varying between 10 and 2 km, and it overlays the Danubian and Getic basements. The Oligocene sequences are filling the basin, with a thickness ranging between 300 and 500 m. They consist of clays, marls, bituminous shales, microconglomerates and limestones, including 22 coal beds. One essential feature of the Petrosani Basin is the occurrence of thick coal seams and the remains of a rich, 28 milion years old ecosystem. The studied material was collected from Uricani coal mine, from the „Lower Productive Horizon", Chattian in age (Upper Oligocene), and from Uricani coal waste dumps. The Lower Productive Horizon, also described as the Dalja-Uricani Formation, includes several coal seams and crops out in several areas (Buia et al., 2014). Collecting fossil plants from underground mining horizons represents a unique method for detailed understanding of coal bearing formations in a three-dimensional approach (Popa, 2011). Although the plant remains are represented by a large number of species, most specimens belong to the Family Lauraceae. The fossil flora is very well preserved, some of the leaves preserving their cuticles. The fossil plants from Uricani coal mine, Petro?ani Basin, are described, illustrated and discussed based on leaf impressions. The associated macroflora of Uricani coal mine comprises various leaf species of Daphnogene, Laurophyllum, Ocotea, Smilax and Alnus. Most of the studied woody plants are mesophytic, like Lauraceae (narrow-leaved Daphnogene, Laurophyllum), but the affinities of the plant remains from Uricani coalfield have not been clarified yet. Nonetheless, the taxonomic composition of the studied flora from Uricani coalfield points to a semi-tropical climate. The overall character of the depositional conditions of Petrosani Basin fit best to a flatland with surrounding

  3. Femoral anatomy of Aegyptopithecus zeuxis, an early oligocene anthropoid.

    Science.gov (United States)

    Ankel-Simons, F; Fleagle, J G; Chatrath, P S

    1998-08-01

    Three partial femora from Quarries I and M of the early Oligocene Jebel Qatrani Formation in the Fayum of Egypt are attributed to Aegyptopithecus zeuxis on the basis of their appropriate size and anthropoid morphology. Compared with extant catarrhines, Aegyptopithecus is unusual in having a distinct gluteal tuberosity (third trochanter) and a relatively deep distal femoral articulation. In the estimated neck angle, Aegyptopithecus resembles arboreal quadrupeds rather than either leaping or suspensory primates. It seems likely that the femur of this species was relatively robust and short for its body mass. In aspects of its femoral anatomy, Aegyptopithecus is quite different from the parapithecid Apidium and more similar to Catopithecus from late Eocene deposits of the Fayum, and also to small hominoids from the Miocene of East Africa.

  4. Oceanographic changes in the Southern Ocean and Antarctic cryosphere dynamics during the Oligocene and Miocene: a view from offshore Wilkes Land

    Science.gov (United States)

    Sangiorgi, Francesca; Bijl, Peter K.; Hartman, Julian D.; Schouten, Stefan; Brinkhuis, Henk

    2016-04-01

    With the ongoing increase in atmospheric CO2 and global temperatures, a fundamental scientific and societal question arises concerning the stability of the Antarctic cryosphere. Modern observational data indicate the Southern Ocean has experienced significant warming, with oceanic fronts being pushed several tenth of km closer to the continent. Moreover, basal melt of ice shelves from warming oceans is causing accelerated grounding line retreat of the Antarctic ice sheets and shelves. However, monitoring data are available for the last few decades only, which prevents the evaluation of long-term changes in ice mass balance. Studying intervals in Earth's past history, which represent the best possible analogues of (near) future conditions, becomes thus essential. The Oligocene and Miocene Epochs encompass periods with CO2 concentrations between today's and those expected for the (near) future. It has also become clear that ice-proximal oceanographic regime is a critical factor for the stability and mass balance of ice sheets. Integrated Ocean Drilling Program (IODP) Expedition 318 offshore Wilkes Land (East Antarctica) Site U1356 satisfies both requirements of being ice-proximal and having a relative complete, stratigraphically well-resolved Oligocene-Miocene sequence (albeit with a possible 5-Myrs gap between Late Oligocene and Early Miocene). This allows for the first time studying oceanographic changes and cryosphere dynamics in the interval ~34-13 Myrs. Thus far, ice-proximal reconstructions were hindered by the paucity of suitable sedimentary archives around Antarctica and/or poor stratigraphic constraints. We reconstructed changes in surface oceanography and seawater temperatures by means of dinoflagellate cyst assemblages and TEX86 paleothermometry. The dinocyst data suggest (summer) sea-ice occurrence at Site U1356 only for the first 1.5 Ma following the onset of full Antarctic glaciation and after the Mid-Miocene Climatic Optimum. In between, both dinocysts

  5. Multi-Epoch XMM Observations of NGC4258

    Science.gov (United States)

    Greenhill, Lincoln J.

    2001-11-01

    The goal of this project is to better understand whether the well known, warped accretion disk around the supermassive black hole in NGC4258 is responsible for the observed X-ray absorbing column of gas. The active galactic nuclei (AGN) paradigm suggests that doughnut-like tori obscure black holes, not warped disks. Using radio interferometry, we have mapped the disk and its orientation. Through time monitoring radio observations we are following the rotation and variability in the disk structure. The disk crosses the line of sight to the black hole, if it is clumpy, then we will observe variations in the X-ray spectrum of NGC4258 on month to year time scales. We have reduced 14 epochs of very long base interferometry (VLBI) observations that we use to characterize the structure of the maser-laden accretion disk and its evolution. Five epochs of data remain to be reduced in the next year. We have received distributions of data for two of our four intended epochs of X-ray Multimirror Mission (XMM) observation. Because the first two epochs are relatively close in time, and because community understanding of how to calibrate XMM data has until recently been relatively immature, we are waiting until we receive the third epoch of data before we reduce the several datasets. Delivery of the third epoch should take place late this year. The last epoch of XMM observation will take place in mid-2002. In the next year, we will begin to combine constraints on disk clumpiness with estimates of X-ray variability observed by XMM.

  6. Morphology and locomotor adaptations of the foot in early Oligocene anthropoids.

    Science.gov (United States)

    Gebo, D L; Simons, E L

    1987-09-01

    Newly discovered foot bones of Aegyptopithecus are described and compared to those of Apidium and Dolichocebus. Locomotor adaptations are inferred for African early Oligocene propliopithecids, parapithecids, and for Argentine early Oligocene Dolichocebus. All show an anthropoid grade of development in their foot anatomy. Tarsals of Aegyptopithecus compare best with those of Miocene hominoids. Apidium shares derived calcaneal features that link it with Old World monkeys. Dolichocebus exhibits a very generalized platyrrhine talar morphology akin to that seen in Saimiri, Callicebus, Cebus, and Aotus. The morphology of early Oligocene primate foot bones suggests that at least three quite distinct groups, corresponding to three recognized superfamilies, were present in the early Oligocene of South America and Africa.

  7. Oligocene sea water temperatures offshore Wilkes Land (Antarctica) indicate warm and stable glacial-interglacial variation and show no 'late Oligocene warming'

    Science.gov (United States)

    Hartman, Julian; Bijl, Peter; Peterse, Francien; Schouten, Stefan; Salabarnada, Ariadna; Bohaty, Steven; Escutia, Carlota; Brinkhuis, Henk; Sangiorgi, Francesca

    2017-04-01

    At present, warming of the waters below the Antarctic ice shelves is a major contributor to the instability of the Antarctic cryosphere. In order to get insight into future melt behavior of the Antarctic ice sheet, it is important to look at past warm periods that can serve as an analogue for the future. The Oligocene ( 34-23 Ma) is a period within the range of CO2 concentrations predicted by the latest IPCC report for the coming century and is characterized by a very dynamic Antarctic ice sheet, as suggested by benthic δ18O records from ice-distal sites. We suspect that, like today, environmental changes in the Southern Ocean are in part responsible for this dynamicity. To gain more insight into this, we have reconstructed sea water temperatures (SWT) based on Thaumarchaeotal lipids (TEX86) for the Oligocene record obtained from the ice-proximal Site U1356 (Integrated Ocean Drilling Program), offshore Wilkes Land. Part of our record shows a strong coupling between the lithology and SWT, which we attribute to glacial-interglacial variation. Our data shows that both glacial and interglacial temperatures are relatively warm throughout the Oligocene: 14°C and 18°C respectively, which is consistent with previously published estimates based on UK'37 and clumped isotopes for the early Oligocene. Our SST records show only a minor decline between 30 and 24 Ma, and thus show no evidence for a 'late Oligocene warming' as was suggested based on benthic δ18O records from low latitudes. Instead, the discrepancy between our SST trend and the δ18O trend suggests that the late-Oligocene benthic δ18O decrease is likely related to a decline in ice volume. After 24 Ma, however, glacial-interglacial temperature variation appears to increase. In particular, some large temperature drops occur, one of which can be related to the Mi-1 event and a major expansion of the Antarctic ice sheet.

  8. THE OLIGOCENE MOLLUSC FAUNA OF THE PIEDMONT BASIN (NORTH-WESTERN ITALY I. SCAPHOPODA AND ARCHAEOGASTROPODA

    Directory of Open Access Journals (Sweden)

    M. CRISTINA BONCI

    2000-07-01

    Full Text Available The aim of the present work is to study the Oligocene Scaphopoda and Archaeogastropoda of the Tertiary Piedmont Basin (T.P.B., aiming towards an overall revision of the Oligocene mollusc fauna of this Basin. Five taxa of Scaphopoda and twenty-eight taxa of Archaeogastropoda have been analysed; among these a new species of Nerita (Theliostyla is proposed. 

  9. Planktic foraminiferal biostratigraphy, paleoecology and chronostratigraphy across the Eocene/Oligocene boundary in northern Tunisia

    Science.gov (United States)

    Karoui-Yaakoub, Narjess; Grira, Chaima; Mtimet, Moncef Saïd; Negra, Mohamed Hédi; Molina, Eustoquio

    2017-01-01

    The biostratigraphic analysis of the Eocene-Oligocene transition of the Menzel Bou Zelfa and Jhaff sections in northeastern Tunisia (Cap Bon peninsula) allows us to identify a continuous planktic foraminiferal biozonation. The following biozones were recognized: Globigerinatheka semiinvoluta Zone (E14), Globigerinatheka index Zone (E15), (Hantkenina alabamensis Zone (E16) of the upper Eocene and Pseudohastigerina naguewichiensis Zone (O1) of the lower Oligocene. A rapid mass extinction event in planktic foraminifera occurred at the Eocene-Oligocene transition, including the extinction of the turborotalids (Turborotalia cerroazulensis, Turborotalia cocoaensis and Turborotalia cunialensis) followed by a significant size reduction of the genus Pseudohastigerina and the extinction of the hantkeninids (Hantkenina alabamensis, Hantkenina brevispina, Hantkenina nanggulanensis and Cribrohantkenina lazzarii), which mark the Eocene/Oligocene boundary. These species were tropical and subtropical surface and intermediate dwellers, with distinctive morphologies (carinate turborotalids and spinose hantkeninids), which were well adapted species of k-strategy. The surviving planktic foraminifera species were quite similar in morphology with globular chambers (globigerinids) and small planispiral (pseudohastigerinids), which were opportunistic species of r-strategy. The recognition of a 4 m thick interval, between the extinction of turborotalids and hantkeninids, indicates that the section is continuous and one of the most expanded throughout the Eocene-Oligocene transition. This section could serve as an auxiliary section (hypostratotype) for the complete definition of the Global Stratotype Section and Point for the Eocene/Oligocene boundary, which mark the base of the Rupelian Stage.

  10. Into the Epoch of Galaxy Formation

    Science.gov (United States)

    2000-02-01

    first of the four 8.2-m VLT Unit Telescopes. A first analysis of the new observations indicates that "evolved" galaxies were already present when the Universe was only 4 billion years old. This information is of great importance to our understanding of how the matter in the early Universe condensed and the first galaxies and stars came into being. While in the nearby Universe evolved galaxies are preferentially located in denser environments such as groups and clusters of galaxies, little is currently known about the distribution in space of such objects at early cosmic epochs. In order to be able to see such obscured and/or "evolved" galaxies in the early Universe, and to look for hitherto unknown galaxies beyond the limits of "deep-field" imaging in visible spectral bands, it is necessary to employ other observing techniques. The astronomers must search for such objects on large-field, very long-exposure sky images obtained in the near-infrared (NIR, wavelength 1-2 µm) region of the electromagnetic spectrum and at even longer wavelengths (> 10 µm) in the far-IR and in the sub-mm range. Such observations are beyond the capability of the infrared cameras installed on the world's 4-m class telescopes. However, the advent of the ISAAC instrument at the 8.2-m ANTU telescope has now opened new and exciting research opportunities in this direction for European astronomers. With ISAAC , it is possible to obtain "deep" NIR images in an unprecedentedly wide field of view, covering a sky area about 7 times larger than with the best instruments previously available on very large telescopes. Such observations also benefit greatly from the very good optical quality provided by the active optics control of the VLT, as well as the excellent Paranal site. The ISAAC/ANTU observations ESO PR Photo 06a/00 ESO PR Photo 06a/00 [Preview - JPEG: 400 x 427pix - 69k] [Normal - JPEG: 800 x 853 pix - 195k] [Full-Res - JPEG: 942 x 1004 pix - 635k] Caption : ESO PR Photo 06a/00 displays a 4

  11. The Cosmic Dawn and Epoch of Reionisation with SKA

    NARCIS (Netherlands)

    Koopmans, L.; Pritchard, J.; Mellema, G.; Aguirre, J.; Ahn, K.; Barkana, R.; van Bemmel, I.; Bernardi, G.; Bonaldi, A.; Briggs, F.; de Bruyn, A. G.; Chang, T. C.; Chapman, E.; Chen, X.; Ciardi, B.; Dayal, P.; Ferrara, A.; Fialkov, A.; Fiore, F.; Ichiki, K.; Illiev, I. T.; Inoue, S.; Jelic, V.; Jones, M.; Lazio, J.; Maio, U.; Majumdar, S.; Mack, K. J.; Mesinger, A.; Morales, M. F.; Parsons, A.; Pen, U. L.; Santos, M.; Schneider, R.; Semelin, B.; de Souza, R. S.; Subrahmanyan, R.; Takeuchi, T.; Vedantham, H.; Wagg, J.; Webster, R.; Wyithe, S.; Datta, K. K.; Trott, C.

    2014-01-01

    Concerted effort is currently ongoing to open up the Epoch of Reionization (EoR) ($z\\sim$15-6) for studies with IR and radio telescopes. Whereas IR detections have been made of sources (Lyman-$\\alpha$ emitters, quasars and drop-outs) in this redshift regime in relatively small fields of view, no dir

  12. The Cosmic Dawn and Epoch of Reionisation with SKA

    NARCIS (Netherlands)

    Koopmans, L.; Pritchard, J.; Mellema, G.; Aguirre, J.; Ahn, K.; Barkana, R.; van Bemmel, I.; Bernardi, G.; Bonaldi, A.; Briggs, F.; de Bruyn, A. G.; Chang, T. C.; Chapman, E.; Chen, X.; Ciardi, B.; Dayal, P.; Ferrara, A.; Fialkov, A.; Fiore, F.; Ichiki, K.; Illiev, I. T.; Inoue, S.; Jelic, V.; Jones, M.; Lazio, J.; Maio, U.; Majumdar, S.; Mack, K. J.; Mesinger, A.; Morales, M. F.; Parsons, A.; Pen, U. L.; Santos, M.; Schneider, R.; Semelin, B.; de Souza, R. S.; Subrahmanyan, R.; Takeuchi, T.; Vedantham, H.; Wagg, J.; Webster, R.; Wyithe, S.; Datta, K. K.; Trott, C.

    2015-01-01

    Concerted effort is currently ongoing to open up the Epoch of Reionization (EoR) ($z\\sim$15-6) for studies with IR and radio telescopes. Whereas IR detections have been made of sources (Lyman-$\\alpha$ emitters, quasars and drop-outs) in this redshift regime in relatively small fields of view, no dir

  13. Multi-epoch Spectropolarimetry of SN 2011fe

    CERN Document Server

    Milne, Peter A; Porter, Amber; Smith, Paul S; Smith, Nathan; Leising, Mark D; Jannuzi, Buell T; Green, E M

    2016-01-01

    We present multiple spectropolarimetric observations of the nearby Type Ia supernova (SN) 2011fe in M101, obtained before, during, and after the time of maximum apparent visual brightness. The excellent time coverage of our spectropolarimetry has allowed better monitoring of the evolution of polarization features than is typical, which has allowed us new insight into the nature of normal SNe Ia. SN 2011fe exhibits time-dependent polarization in both the continuum and strong absorption lines. At early epochs, red wavelengths exhibit a degree of continuum polarization of up to 0.4\\%, likely indicative of a mild asymmetry in the electron-scattering photosphere. This behavior is more common in sub-luminous SNe Ia than in normal events, such as SN2011fe. The degree of polarization across a collection of absorption lines varies dramatically from epoch to epoch. During the earliest epoch a $\\lambda$4600-5000 \\AA\\ complex of absorption lines shows enhanced polarization at a different position angle than the continuum...

  14. The LOFAR Epoch of Reionization Data Model : Simulations, Calibration, Inversion

    NARCIS (Netherlands)

    Lampropoulos, Panagiotis

    One of the most exciting applications of LOFAR will be the search for redshifted 21-cm line emission from the Epoch of Reionization (EOR). It is currently believed that the Dark Ages, the period after recombination when the Universe turned neutral, lasted until around the Universe was 400,000 years

  15. The hydrocarbon prospectivity of lower oligocene deposits in the Maragh Trough, Se Sirt Basin, Libya

    Energy Technology Data Exchange (ETDEWEB)

    Gruenwald, R. [Wintershall Libya, Tripoli (Libya)

    2001-04-01

    The main phase of rifting the Sirt Basin (Libya) had ceased by the mid-Cretaceous but later Alpine-related tectonic pulses in the late Eocene resulted in northward tilting of the basin. In the Maragh Trough (SE Sirt basin), a regional unconformity consequently separates Eocene carbonates from the overlying Oligocene succession. The unconformity marks a change from Eocene fully-marine sedimentation to more mixed, shallow-marine type deposition in the Oligocene. A regional transgression re-established fully marine conditions in the Miocene. Deeply-buried (Triassic) source rocks in the Maragh Trough reached peak oil generation during the Oligocene. Two potential reservoir intervals have been identified: upper Eocene rudstones of the Augila Formation, and unconformably-overlying sandstones of the Lower Oligocene Arida Formation. Mid-Oligocene shales provide a regional seal. Facies distributions and reservoir properties are related to rift-related structural highs. Despite the absence of a nearby source kitchen, Upper Eocene carbonates have been found to be oil-bearing in the Maragh Trough at wells D1- and F1-96. This indicates that hydrocarbons have migrated along graben-bounding faults from deeply-buried source rocks to platform and sub-platform areas. Traps are of combined structural and stratigraphic type. (author)

  16. Arctic Dinoflagellate Migration Marks the Oligocene Glacial Maximum: Implications for the Rupelian-Chattian Boundary

    Science.gov (United States)

    van Simaeys, S.; Brinkhuis, H.; Pross, J.; Williams, G. L.; Zachos, J. C.

    2004-12-01

    Various geochemical and biotic climate proxies, and notably deep-sea benthic foraminiferal δ 18O records indicate that the Eocene 'greenhouse' state of the Earth gradually evolved towards an earliest Oligocene 'icehouse' state, eventually triggering the abrupt appearance of large continental ice-sheets on Antarctic at ˜33.3 Ma (Oi-1 event). This, however, was only the first of two major glacial events in the Oligocene. Benthic foraminiferal δ 18O records show a second positive excursion in the mid Oligocene, consistent with a significant ice-sheet expansion and/or cooling at 27.1 Ma (Oi-2b) coincident with magnetosubchron C9n. Here, we report on a mid Oligocene, globally synchronous, Arctic dinoflagellate migration event, calibrated against the upper half of C9n. A sudden appearance, and abundance increases of the Arctic taxon Svalbardella at lower-middle latitudes coincides with the so-called Oi-2b benthic δ 18O event, dated at ˜27.1 Ma. This phenomenon is taken to indicate significant high-latitude surface water cooling, concomitant Antarctic ice-sheet growth, and sea level lowering. The duration of the Svalbardella migrations, and the episode of profound cooling is estimated as ˜500 ka, and is here termed the Oligocene Glacial Maximum (OGM). Our records suggest a close link between the OGM, sea-level fall, and the classic Rupelian-Chattian boundary, magnetostratigraphically dating this boundary as ˜27.1 Ma.

  17. Paleoclimate Changes during the Early Oligocene in the Hoh Xil Region, Northern Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    LIU Zhifei; WANG Chengshan; Alain TRENTESAUX; ZHAO Xixi; YI Haisheng; HU Xiumian; JIN Wei

    2003-01-01

    Sedimentological, cyclic-stratigraphic, paleomagnetic, and clay-mineralogical studies on the earlyOligocene Yaxicuo Group in the Hoh Xil Basin, the largest Cenozoic sedimentary basin in the hinterland of the TibetanPlateau, provide abundant information of paleoclimate changes. A 350-m thick section in the middle-lower YaxicuoGroup was analyzed to reveal the climatic history that occurred in the Hoh Xil region during the early Oligocene interval31.30-30.35 Ma, dated with the paleomagnetic chronostratigraphy. The results indicate that arid and cold climatedominated the Hoh Xil region during the early Oligocene in general, being related to the global cooling and dryingevents that occurred in the earliest Oligocene. Within this period, relatively warm and wet climate accompanied bystrong tectonic activity occurred in the 31.05-30.75 Ma interval; while arid and cold climate and relatively inactivetectonics occurred in the 31.30-31.05 and 30.75-30.35 Ma intervals. Furthermore, spectral analyses of high-temporalresolution paleoclimatic records show orbital periods including eccentricity, obliquity, and precession. It is concludedthat paleoclimate changes during the early Oligocene in the Hoh Xil region were forced by both tectonic activity andorbital periods.

  18. Observing the reionization epoch through 21-centimetre radiation

    Science.gov (United States)

    Furlanetto, Steven R.; Sokasian, Aaron; Hernquist, Lars

    2004-01-01

    We study the observability of the reionization epoch through the 21-cm hyperfine transition of neutral hydrogen. We use a high-resolution cosmological simulation (including hydrodynamics) together with a fast radiative transfer algorithm to compute the evolution of 21-cm emission from the intergalactic medium (IGM) in several different models of reionization. We show that the mean brightness temperature of the IGM drops from δTb~ 25 mK to ~10-2 mK during overlap (over a frequency interval Δν~ 25 MHz), while the root mean square fluctuations on small scales drop abruptly from 1/2~ 10 mK to ~10-1 mK at the end of overlap. We show that 21-cm observations can efficiently discriminate models with a single early reionization epoch from models with two distinct reionization episodes.

  19. Rapid Oligocene Exhumation of the Western Canadian Rocky Mountains

    Science.gov (United States)

    Szameitat, A.; Parrish, R. R.; Stuart, F. M.; Carter, A.; Fishwick, S.

    2014-12-01

    As part of the North American Cordillera the Rocky Mountains of Canada impact the deflection of weather systems and the jet stream and form a distinct barrier to Pacific moisture reaching the continental interior. The extent to which this climatic pattern extended into the past is at present uncertain, so improving our understanding of the elevation history of the Rockies is critical to determining the controls on climate change within the Northern Hemisphere. We have undertaken a comprehensive apatite (U-Th-Sm)/He and fission track study of the southeastern Canadian Cordillera, i.e. the southern Canadian Rocky Mountains, in order to provide insight into the mid to late Cenozoic uplift and exhumation history of this region. Thermal history and exhumation models of widespread low elevation samples in combination with 6 vertical profiles covering elevations from 500 up to 3100 m a.s.l. show at least 1500 m of rapid exhumation west of the Rocky Mountain Trench (RMT) during the Oligocene (Figure 1). In contrast, the ranges east of the RMT low elevation samples provide Eocene ages throughout. The data show a very different history of recent uplift of the Canadian Rockies compared to what is currently known from published work, which mostly infer that the eastern Canadian Cordillera has not experienced significant uplift since the Eocene. We propose that the most likely cause of this rock uplift was upwelling of asthenosphere around the eastward subducting Farallon Plate. This also led to the eruption of the nearby mainly Miocene Chilcotin Group flood basalts and could have caused underplating of the thin lithosphere west of the RMT, adding to the buoyancy of the plate and lifting the range. Because the Trench marks the edge of the normal thickness craton which was underthrust beneath the Rocky Mountains during the initial upper Cretaceous orogeny, the eastern Rockies have a normal lithosperic thickness. This would impede recent uplift and provides an explanation for the

  20. Affordability Tradeoffs Under Uncertainty Using Epoch-Era Analysis

    Science.gov (United States)

    2013-09-30

    run. Many investigations have been conducted into major causes of cost and schedule growth in defense acquisition. A 2009 report by Porter et al. has...definition and costing ( Porter et al., 2009). The second category encompasses failures in systems design and early- phase planning, as well as unrealistic...across the six representative epochs (shown in Figure 22) are listed in Figure 30.   Design # NPT  Blue Diamond 1 0 Red Square 2 1 Green Triangle 3

  1. First perissodactyl footprints from Flysch deposits of the Barail Group (Lower Oligocene) of Manipur, India

    Science.gov (United States)

    Rajkumar, Hemanta Singh; Klein, Hendrik

    2014-03-01

    Two pes imprints of a perissodactyl mammal constituting a single step of a trackway have recently been discovered in Oligocene Flysch deposits of the Barail Group in Manipur, India. The tridactyl, mesaxonic imprints (~7 cm in length) show strong similarities to footprints known from the Paleogene of China and can be attributed to a tapiroid, rhinocerotoid or equoid trackmaker. This is the first record of perissodactyl footprints from the Lower Oligocene of India and the first evidence of mammals in the Barail Group of the age. Remarkable is the occurrence in a marginal marine setting, whereas other known perissodactyl footprints from the Eocene-Oligocene in particular from North America, Europe and China come from fluvio-lacustrine strata.

  2. Paliurus Fruits from the Oligocene of South China and Their Phytogeographic Implications.

    Directory of Open Access Journals (Sweden)

    Jun-Ling Dong

    Full Text Available Paliurus favonii Unger is recognized and described based on fruits from the Oligocene Ningming flora of Guangxi, South China. Characteristics of the present specimens include circular winged fruits that are 10.0-11.5 mm in diameter with a central endocarp at 3.0 to 4.0 mm in diameter. The specimens fall into the morphological range of the fossil species P. favonii, which has been observed in other Cenozoic sites in the Northern Hemisphere. The present discovery represents the lowest latitude distribution of P. favonii in the world, and we are presenting the first P. favonii fossil described with detailed cuticular characteristics from China. Further, this finding demonstrates that the genus existed in the Oligocene Ningming region, South China, and provides new information for understanding the fossil history. The dispersal mode for winged fossils demonstrates that wind dispersal is well-represented in the Oligocene Ningming flora.

  3. Paliurus Fruits from the Oligocene of South China and Their Phytogeographic Implications.

    Science.gov (United States)

    Dong, Jun-Ling; Sun, Bai-Nian; Ma, Fu-Jun; Wang, Qiu-Jun; Jin, Pei-Hong; Wang, Wen-Jia; Deng, Peng; Yang, Yi; Li, Xiao-Jing

    2015-01-01

    Paliurus favonii Unger is recognized and described based on fruits from the Oligocene Ningming flora of Guangxi, South China. Characteristics of the present specimens include circular winged fruits that are 10.0-11.5 mm in diameter with a central endocarp at 3.0 to 4.0 mm in diameter. The specimens fall into the morphological range of the fossil species P. favonii, which has been observed in other Cenozoic sites in the Northern Hemisphere. The present discovery represents the lowest latitude distribution of P. favonii in the world, and we are presenting the first P. favonii fossil described with detailed cuticular characteristics from China. Further, this finding demonstrates that the genus existed in the Oligocene Ningming region, South China, and provides new information for understanding the fossil history. The dispersal mode for winged fossils demonstrates that wind dispersal is well-represented in the Oligocene Ningming flora.

  4. First perissodactyl footprints from Flysch deposits of the Barail Group (Lower Oligocene) of Manipur, India

    Indian Academy of Sciences (India)

    Hemanta Singh Rajkumar; Hendrik Klein

    2014-03-01

    Two pes imprints of a perissodactyl mammal constituting a single step of a trackway have recently been discovered in Oligocene Flysch deposits of the Barail Group in Manipur, India. The tridactyl, mesaxonic imprints (∼7 cm in length) show strong similarities to footprints known from the Paleogene of China and can be attributed to a tapiroid, rhinocerotoid or equoid trackmaker. This is the first record of perissodactyl footprints from the Lower Oligocene of India and the first evidence of mammals in the Barail Group of the age. Remarkable is the occurrence in a marginal marine setting, whereas other known perissodactyl footprints from the Eocene–Oligocene in particular from North America, Europe and China come from fluvio-lacustrine strata.

  5. Comparing Simulations and Observations of Reionization-Epoch Galaxies

    Science.gov (United States)

    Dave, Romeel; Finlator, Kristian

    2006-05-01

    We propose to test and constrain models of early galaxy formation through comparisons with observations of reionization-epoch (z>6) galaxies observed using Spitzer. The goals are to (1) Make predictions for z>6 objects using state-of-the-art cosmological hydrodynamic simulations of galaxy formation tailored to study the reionization epoch; (2) Develop a publicly-available tool called SPOC designed to obtain detailed constraints on physical properties of observed galaxies through comparisons with simulated galaxy catalogs; and (3) Use SPOC to test and constrain models of galaxy formation through comparisons with rapidly- advancing observations in the new frontier of early universe studies. The results of this study will yield deeper insights into the galaxy formation process at these mostly unexplored epochs, with implications for understanding the formation of massive galaxies, studying the topology and evolution of IGM reionization, and designing future surveys to detect first objects. The SPOC tool will facilitate a closer connection between observations and theory by enabling the community to interpret data within the framework of current hierarchical structure formation models, in turn providing detailed tests of these models that is essential for driving the field forward.

  6. New primate fossils from late Oligocene (Colhuehuapian) localities of Chubut Province, Argentina.

    Science.gov (United States)

    Fleagle, J G; Bown, T M

    1983-01-01

    New primate fossils have been recovered from the late Oligocene (Colhuehuapian) localities of Gaiman and Sacanana in Patagonian Argentina. The new fossils are provisionally allocated to Dolichocebus gaimanensis and Tremacebus harringtoni, the only primates previously described from these localities. These new dental remains are more primitive than the teeth of any previously known platyrrhines, living or fossil, and conform extremely well with the hypothetical ancestral morphotype for New World monkeys suggested by several authors. They are also very similar to the teeth of Oligocene catarrhines from Egypt such as Aegyptopithecus zeuxis.

  7. Exploration possibilities of Oligocene coal seams in the vicinity of Mogyorosbanya and Szarkaspuszta

    Energy Technology Data Exchange (ETDEWEB)

    Gidai, L.

    1986-01-01

    In the Dorog Basin (North Trabnsdanubia) the Oligocene coal seams lie in much smaller depths than the Eocene ones, thus the prospective coal reserves could be mined under less dangerous conditions (water inrush etc.). A review of the history of exploration is given together with the demonstration of the structural-tectonic position of the area in question. The distribution and extension as well as the quality and thickness of the Oligocene coal seams are discussed with special reference to the strata columns. Eight regions are distinguished that may be suitable for economic use.

  8. Exploration possibilities of Oligocene brown coal seams in the Vertessomio - Majkpuszta - Orosziany region

    Energy Technology Data Exchange (ETDEWEB)

    Gidai, L.

    1986-01-01

    The history of exploration, the stratigraphic conditions of the Oligocene formations together with the tectonics of the region are discussed. Based on exploration borehole data the expected thickness and distribution of the coal seams are presented. As demonstrated by the isopach lines the depth of the Oligocene coal seams varies between 50 and 300 mm below the surface, i.e. the beds lie somewhat higher than the Eocene coal-bearing strata. For this very reason the region seems to be extractable though the thickness of the coal seams falls behind the Eocene ones.

  9. Oligocene to Miocene terrestrial climate change and the demise of forests on Wilkes Land, East Antarctica

    Science.gov (United States)

    Salzmann, Ulrich; Strother, Stephanie; Sangiorgi, Francesca; Bijl, Peter; Pross, Joerg; Woodward, John; Escutia, Carlota; Brinkhuis, Henk

    2016-04-01

    The question whether Cenozoic climate was warm enough to support a substantial vegetation cover on the Antarctic continent is of great significance to the ongoing controversial debate on the dynamic behaviour of Antarctic land ice during the transition from a greenhouse to an icehouse world. Here we present palynological results from an Oligocene to Miocene sediment record provided by the Integrated Ocean Drilling Program Expedition 318 to the Wilkes Land margin (East Antarctica). The Oligocene assemblages (33.9-23 Ma) are dominated by pollen and spores from temperate forest and sub-Antarctic shrub vegetation inhabiting different altitudinal zones. These include a lowland cold temperate forest with Dacrydium and Lagarostrobos (both common in southern forests of New Zealand and Tasmania today) and a high altitude tundra shrubland comprising Microcachrys, Nothofagus (southern beech) and Podocarpaceae conifers. A decline in pollen percentages of Dacrydium and Lagarostrobos and absence of Proteaceae indicate climate cooling during the late Oligocene (~25-23 Ma). However, the continuous presence of Lagarostrobos suggests that the full transition to a tundra environment had not yet occurred and climate on Wilkes Land during the late Oligocene was still warm enough to support forest vegetation in sheltered areas. Temperature reconstructions derived from the fossil pollen assemblages using the Coexistence Approach suggest mean annual temperatures (MATs) between 6.7-13.7°C during the early Oligocene and a drop of minimum MATs to 5.8°C in the late Oligocene. Pollen of "unambiguous" forest indicators, such as Lagarostrobos, are absent in the Miocene sediment record (16.2 -12.5 Ma) but temperatures were still high enough (minimum MATs > 5°C) to sustain a woody sub-Antarctic vegetation under partially ice-free conditions. Wilkes Land provides a unique record of Antarctic vegetation change from a subtropical, highly diverse Eocene rainforest to an Oligocene cold temperate

  10. Metamorphic conditions and CHIME monazite ages of Late Eocene to Late Oligocene high-temperature Mogok metamorphic rocks in central Myanmar

    Science.gov (United States)

    Maw Maw Win; Enami, Masaki; Kato, Takenori

    2016-03-01

    The high temperature (T)/pressure (P) regional Mogok metamorphic belt is situated in central Myanmar, and is mainly composed of pelitic gneisses, amphibolites, marbles, and calc-silicate rocks. The garnet-biotite-plagioclase-sillimanite-quartz assemblage and its partial system suggest equilibrium P/T conditions of 0.6-1.0 GPa/780-850 °C for the peak metamorphic stage, and 0.3-0.5 GPa/600-680 °C for the exhumation and hydration stage. Monazite grains show complex compositional zoning consisting of three segments-I, II, and III. Taking into consideration the monazite zoning and relative misfit curves, the calculated chemical Th-U-total Pb isochron method (CHIME) monazite age data (284 spot analyses) indicated four age components: 49.3 ± 2.6-49.9 ± 7.9, 37.8 ± 1.0-38.1 ± 1.7, 28.0 ± 0.8-28.8 ± 1.6, and 23.7 ± 1.3 Ma (2σ level). The ages of the Late Eocene and Late Oligocene epochs were interpreted as the peak metamorphic stage of upper-amphibolite and/or granulite facies and the postdated hydration stage, respectively.

  11. Oligocene terrestrial strata of northwestern Ethiopia : a preliminary report on paleoenvironments and paleontology

    Science.gov (United States)

    Bonnie F. Jacobs; Neil Tabor; Mulugeta Feseha; Aaron Pan; John Kappelman; Tab Rasmussen; William Sanders; Michael Wiemann; Jeff Crabaugh; Juan Leandro Garcia Massini

    2005-01-01

    The Paleogene record of Afro-Arabia is represented by few fossil localities, most of which are coastal. Here we report sedimentological and paleontological data from continental Oligocene strata in northwestern Ethiopia. These have produced abundant plant fossils and unique assemblages of vertebrates, thus filling a gap in what is known of Paleogene interior Afro-...

  12. Triggers and consequences of glacial expansion across the Eocene - Oligocene Transition

    NARCIS (Netherlands)

    Houben, A.J.P.

    2012-01-01

    The results described in this thesis provide a rather complex picture of climatic, environmental and biotic changes preceding and arising from the onset of Antarctic glaciation. This period is commonly known as the greenhouse to icehouse transition across the Eocene-Oligocene Transition (EOT, 34-33

  13. Effect of ocean gateways on the global ocean circulation in the late Oligocene and early Miocene

    NARCIS (Netherlands)

    von der Heydt, A.S.|info:eu-repo/dai/nl/245567526; Dijkstra, H.A.|info:eu-repo/dai/nl/073504467

    2006-01-01

    We investigate the effect of changes in the tectonic boundary conditions on global ocean circulation patterns. Using a fully coupled climate model in an idealized setup, we compare situations corresponding to the late Oligocene, the early Miocene, and present day. The model results show the

  14. Decapod crustaceans from the Oligocene of the Ligure Piemontese Basin, northern Italy

    NARCIS (Netherlands)

    Angeli, De Antonio; Marangon, Sergio

    2003-01-01

    Lithologically, the decapod-bearing levels of Rupelian (Oligocene) age in the Ligure Piemontese Basin, are characterized by an alternation of greyish blue marls with nodular elements and silt-rich, occasionally sandy, marls. The fossil studied for the present note have been collected mainly from

  15. Upper Oligocene micromammals from Pareja, Loranca Basin, Prov. of Guadalajara, Spain

    NARCIS (Netherlands)

    Daams, R.; Freudenthal, M.; Lacomba, J. I.; Alvarez, M.A.

    1989-01-01

    Eight rodent species from the Upper Oligocene of Pareja are described. The Theridomyidae are represented by Issiodoromys minor and Archaeomys (A.) gervaisi and the Eomyidae by Eomys cf. molassicus. Four cricetid species are described: Heterocricetodon landroveri sp. nov., Eucricetodon margaritae sp.

  16. Oligocene marine Date Mussel from Plaznica brook near Poljšica, West Slovenia

    OpenAIRE

    Vasja Mikuž

    2006-01-01

    In paper the bivalve of species Lithophaga ornatissima (Mayer-Eymar, 1886) is described,found in a corallite in Oligocene beds of the Plaznica creek at Poljšica near Podnart.This is the first find of this litophaga species in Slovenia. In literature no finds of fossil date mussels are mentioned from surroundings of Polj{ica in Upper Carniola.

  17. Decapod crustaceans from the Oligocene of the Ligure Piemontese Basin, northern Italy

    NARCIS (Netherlands)

    Angeli, De Antonio; Marangon, Sergio

    2003-01-01

    Lithologically, the decapod-bearing levels of Rupelian (Oligocene) age in the Ligure Piemontese Basin, are characterized by an alternation of greyish blue marls with nodular elements and silt-rich, occasionally sandy, marls. The fossil studied for the present note have been collected mainly from peb

  18. Upper Oligocene micromammals from Pareja, Loranca Basin, Prov. of Guadalajara, Spain

    NARCIS (Netherlands)

    Daams, R.; Freudenthal, M.; Lacomba, J. I.; Alvarez, M.A.

    1989-01-01

    Eight rodent species from the Upper Oligocene of Pareja are described. The Theridomyidae are represented by Issiodoromys minor and Archaeomys (A.) gervaisi and the Eomyidae by Eomys cf. molassicus. Four cricetid species are described: Heterocricetodon landroveri sp. nov., Eucricetodon margaritae sp.

  19. Morphology of an Early Oligocene beaver Propalaeocastor irtyshensis and the status of the genus Propalaeocastor.

    Science.gov (United States)

    Li, Lüzhou; Li, Qiang; Lu, Xiaoyu; Ni, Xijun

    2017-01-01

    The Early to Late Oligocene Propalaeocastor is the earliest known beaver genus from Eurasia. Although many species of this genus have been described, these species are defined based on very fragmentary specimens. Propalaeocastor irtyshensis from the Early Oligocene Irtysh River Formation in northwestern Xinjiang, China is one of the earliest-known members of Propalaeocastor. This species is defined on a single maxillary fragment. We revise the diagnosis of P. irtyshensis and the genus Propalaeocastor, based on newly discovered specimens from the Irtysh River Formation. The dental morphology of P. irtyshensis is very similar to other early castorids. The caudal palatine foramen of P. irtyshensis is situated in the maxillary-palatine suture. This is a feature generally accept as diagnostic character for the castorids. On the other hand, P. irtyshensis has two upper premolars, a rudimentarily developed sciuromorph-like zygomatic plate, and a relatively large protrogomorph-like infraorbital foramen. Some previous researchers suggested that Propalaeocastor is a junior synonym of Steneofiber, while other took it as a valid genus. Our morphological comparison and phylogenetic analysis suggest that Propalaeocastor differs from Steneofiber and is a valid genus. We also suggest that Agnotocastor aubekerovi, A. coloradensis, A. galushai, A. readingi, Oligotheriomys primus, and "Steneofiber aff. dehmi" should be referred to Propalaeocastor. Propalaeocastor is the earliest and most basal beaver. The origin place of Propalaeocastor and castorids is uncertain. The Early Oligocene radiation of castorids probably is propelled by the global climate change during the Eocene-Oligocene transition.

  20. Pentadinium alabamensis: A new, unusual dinoflagellate from the early Oligocene of the Gulf Coast, Alabama, USA

    NARCIS (Netherlands)

    Quaijtaal, W.; Brinkhuis, H.

    2012-01-01

    The Eocene–Oligocene Transition (EOT, ~ 34 Ma) marks the onset of major Antarctic ice sheets. The environmental consequences of the transition included major changes in e.g., sea level, temperature, and ocean circulation, complicating biostratigraphic correlations in this interval. Organic walled di

  1. Observing the Reionization Epoch Through 21 Centimeter Radiation

    OpenAIRE

    Furlanetto, Steven; Sokasian, Aaron; Hernquist, Lars

    2003-01-01

    We study the observability of the reionization epoch through the 21 cm hyperfine transition of neutral hydrogen. We use a high-resolution cosmological simulation (including hydrodynamics) together with a fast radiative transfer algorithm to compute the evolution of 21 cm emission from the intergalactic medium (IGM) in several different models of reionization. We show that the mean brightness temperature of the IGM drops from dT_b~25 mK to dT_b~0.01 mK during overlap (over a frequency interval...

  2. 'Anthropocene': An Ethical Crisis, Not a Geological Epoch

    Science.gov (United States)

    Cuomo, Chris

    2017-04-01

    The term 'anthropocene' has gained enormous popularity among scientists who believe we are in a global phase distinguished by the extensive and lasting impacts of social activities on Earth's sedimentary record and vital systems. Beyond its widespread informal use, a working group of the International Union of Geological Sciences seeks to formalize the term to name a new geological epoch, implying that the Holocene epoch has ended. I argue that the move to formalize the 'anthropocene' and to declare the demise of the Holocene is premature and ethically misguided, at best, and that the very name 'anthropocene' obscures rather than illuminates the serious moral and political/economic implications of the dire warnings evident in recent stratigraphic and ecological changes. If human-caused mass extinction and other ecological catastrophes are serious harms, ethical responses are required. Instead, the move to formalize the idea of an 'anthropocene' epoch treats dire ethical warnings as an opportunity to redefine the current dangerous situation as a new status quo. Have we met our responsibilities to protect Holocene Earth? This presentation will focus on the ethical implications of using the power and discourse of geology to demote Holocene ecological states from their role as the foundational benchmarks for guiding and assessing human relationships with nature and other species. Have geoscientists adequately consulted the biological, ecological and social sciences before declaring the end of the Holocene epoch? Upon what do we base environmental ethics if the Holocene is considered past history? I will also examine the ethical dimensions of naming the so-called 'anthropocene', asking: who is the presumed 'anthro' in the 'anthropocene'? Are the phenomena identified with the 'anthropocene' (nuclear fallout, mass species endangerment, ocean acidification, fossil fuel pollution, deforestation, mining) definitive accomplishments of the human species? Should the practices

  3. Late Globalization and Evolution, Episodes and Epochs of Industries

    DEFF Research Database (Denmark)

    Turcan, Romeo V.; Boujarzadeh, Behnam; Dholakia, Nikhilesh

    While the empirical focus of this paper is the Danish Textile and Fashion Industry (DTFI) – specifically the episodes and epochs in the emergence and evolution of DTFI, in essence the micro and macro time-slices – the theoretical intent is wider. We aim to explore the conceptual terrain of what we...... term “late globalization”, a terrain that has temporal and spatial aspects along with many other dimensions. DTFI as a late globalizer with its specific pattern, with ups and downs as well as innovations and adaptations, provides a specific window into late globalization processes; and sets a stage...

  4. Cyclone trends constrain monsoon variability during late Oligocene sea level highstands (Kachchh Basin, NW India)

    Science.gov (United States)

    Reuter, M.; Piller, W. E.; Harzhauser, M.; Kroh, A.

    2013-09-01

    Climate change has an unknown impact on tropical cyclones and the Asian monsoon. Herein we present a sequence of fossil shell beds from the shallow-marine Maniyara Fort Formation (Kachcch Basin) as a recorder of tropical cyclone activity along the NW Indian coast during the late Oligocene warming period (~ 27-24 Ma). Proxy data providing information about the atmospheric circulation dynamics over the Indian subcontinent at this time are important since it corresponds to a major climate reorganization in Asia that ends up with the establishment of the modern Asian monsoon system at the Oligocene-Miocene boundary. The vast shell concentrations are comprised of a mixture of parautochthonous and allochthonous assemblages indicating storm-generated sediment transport from deeper to shallow water during third-order sea level highstands. Three distinct skeletal assemblages were distinguished, each recording a relative storm wave base. (1) A shallow storm wave base is shown by nearshore molluscs, reef corals and Clypeaster echinoids; (2) an intermediate storm wave base depth is indicated by lepidocyclinid foraminifers, Eupatagus echinoids and corallinacean algae; and (3) a deep storm wave base is represented by an Amussiopecten bivalve-Schizaster echinoid assemblage. These wave base depth estimates were used for the reconstruction of long-term tropical storm intensity during the late Oligocene. The development and intensification of cyclones over the recent Arabian Sea is primarily limited by the atmospheric monsoon circulation and strength of the associated vertical wind shear. Therefore, since the topographic boundary conditions for the Indian monsoon already existed in the late Oligocene, the reconstructed long-term cyclone trends were interpreted to reflect monsoon variability during the initiation of the Asian monsoon system. Our results imply an active monsoon over the Eastern Tethys at ~ 26 Ma followed by a period of monsoon weakening during the peak of the late

  5. Greenland ice sheet initiation and Arctic sea ice coincide with Eocene and Oligocene CO2 changes

    Science.gov (United States)

    Tripati, Aradhna; Darby, Dennis

    2016-04-01

    Earth's modern ocean-climate system is largely defined by the presence of glacial ice on landmasses in both hemispheres. Northern Hemisphere ice was previously thought to have formed no earlier than the Miocene or Oligocene, about 20-30 million years after the widespread onset of Antarctic glaciation at the Eocene-Oligocene boundary. Controversially, the episodic presence of seasonal Arctic sea ice and glacial ice in the Northern Hemisphere beginning in the early Oligocene to Middle Eocene has been inferred from multiple observations. Here we use precise source determinations based on geochemical measurements of ice-rafted debris (IRD) from an ODP core in the Greenland Sea (75° N) to constrain glacial ice and sea ice-rafting in the Northern Hemisphere during the middle Eocene through early Oligocene. The chemical fingerprint of 2,334 detrital Fe oxide grains indicates most of these grains are from Greenland with >98% certainty. Thus the coarse IRD in the Greenland Sea originates from widespread areas of east Greenland as far south as the Denmark Strait area (~68° N), with additional IRD sources from the circum-Arctic Ocean. This is the first definitive evidence that mid-Eocene IRD in the Greenland Sea is from Greenland. Episodic glaciation of different source regions on Greenland is synchronous with times of ice-rafting in the western Arctic and ephemeral perennial Arctic ice cover. Intervals of bipolar glacial ice storage in the middle Eocene through early Oligocene coincide with evidence for periods of reduced CO2, associated with carbon cycle perturbations.

  6. Deep-water Earliest Oligocene Glacial Maximum (EOGM) in South Atlantic

    Institute of Scientific and Technical Information of China (English)

    LIU Zhifei; TUO Shouting; ZHAO Quanhong; CHENG Xinrong; HUANG Wei

    2004-01-01

    The most prominent cooling event of the Earth surface during Cenozoic in the long-term transition from a non-glaciated planet, or "green-house world", to a polar, glaciated planet, or "ice-house world", is the Earliest Oligocene Glacial Maximum (EOGM) above the Eocene/Oligocene boundary at about 33.7 Ma. Planktonic and benthic foraminiferal oxygen and carbon isotopes, carbonate content, and coarse fraction, along with high-resolution color reflectance and magnetic susceptibility records during 35-30 Ma, from deep-water Sites 1262 and 1265, Ocean Drilling Program (ODP) Leg 208 in South Atlantic, reveal the global cooling event occurring in both surface and deep oceans. The results show that the earliest Oligocene δ18O values during 33.5-33.1 Ma represent the magnitude of continental ice sheets on east Antarctica and indicate the large decrease in both surface and deep water temperatures of worldwide oceans. The δ13C records show the large excursion during the period of EOGM event and indicate some types of shift in global carbon reservoir, probably demonstrating the sudden increase in organic carbon burial rates and the changes in the distribution and timing of production. At the same time, lithologic composition, carbonate content, color reflectance, and coarse fraction brought about significant changes close to the Eocene/Oligocene boundary, reflecting the abrupt deepening in the carbonate compensation depth (CCD). Changes in carbonate content were revealed from the color reflectance identify periodicities associated with eccentricity of the Earth's orbit (100 and 400 ka), further indicating orbitally forced global climate variations in the Early Oligocene.

  7. Moon-based Epoch of Reionization Imaging Telescope (MERIT)

    Science.gov (United States)

    Jones, D. L.; MacDowall, R. J.; Bale, S. D.; Demaio, L.; Kasper, J. C.; Weiler, K. W.

    2005-05-01

    Radio observations of emission and absorption from neutral Hydrogen during the Epoch of Reionization (EoR) can reveal how structure leading to the first stars, galaxies, and black holes formed in the intergalactic medium between redshifts of about 6 and at least 20. Ground-based low frequency radio arrays are under construction (LOFAR, PAST) or development (LWA, MWA) to detect and eventually image the EoR signal. The Moon-based Epoch of Reionization Imaging Telescope (MERIT) is a mission concept that is intended to extend ground-based observations of the EoR to the highest possible dynamic range and image fidelity. This can be accomplished by locating the MERIT array on the far side of the moon. The array is composed of 10-12 radial arms, each 1-2 km in length. Each arm has several hundred dipole antennas and feedlines printed on a very thin sheet of kapton with a total mass of about 300 kg. This provides a convenient way to deploy thousands of individual antennas, and a centrally condensed distribution of array baselines. The lunar farside provides shielding from terrestrial natural and technological radio interference, shielding (half the time) from strong solar radio emissions, and freedom from the corrupting influence of Earth's ionosphere. Various options for array deployment and data transmission to Earth will be described is this paper. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  8. Early Science from the Hydrogen Epoch of Reionization Array

    Science.gov (United States)

    Jacobs, Daniel; HERA Team

    2017-01-01

    The Hydrogen Epoch of Reionization Array (HERA) is a radio interferometer targeting 21cm emission from the primordial intergalactic medium. Observing across a broad redshift range HERA will directly measure the IGM as it is heated and ionized by the first galaxies and black holes. HERA is tuned to make a precision measurement of the HI power spectrum through redshifts 6 to 12, capturing, at high significance, the spatial and temporal pattern of fluctuations imprinted by early objects and will explore beyond to redshift 20 to epochs driven by the very first objects. When completed, the array will have 250 14m dishes packed into a regular hexagonal pattern for roughly 10 times the sensitivity of previous such arrays. HERA is an official Square Kilometer Array precursor operated out of the South African SKA site. It is a staged experimental program that is building out in steps; 19 dishes are operating at the , the next expansion to 37 is under way in parallel with commissioning experiments. Here we report on these tests which have focused on optimizing feed design and calibration techniques and discuss their impact on isolation of foreground emission.

  9. Improved Water Level Retrieval from Epoch-by-Epoch Single and Double Difference GNSS-R Algorithms

    Directory of Open Access Journals (Sweden)

    WANG Nazi

    2016-07-01

    Full Text Available GNSS-R is a new technology for monitoring the water level with high efficiency. Compared with conventional water level measurement technique, such as satellite altimetry and tide gauges, GNSS-R can observe more reflected points with high temporal and spatial resolution and unaffected by the influence of the plate vertical motion. This paper presented an improved cGNSS-R altimetry algorithm based on single difference to derive the reflector heights epoch-by-epoch, which can enhance the temporal and spatial resolution of surface height measurements, furthermore, the other algorithm based on the double differenced carrier phase measurements was also presented in this paper. By using the observed data of cGNSS-R altimetry experiment conducted on Qinghe bridge of East Lake, Wuhan, the reflector heights between the reflected antenna and the lake surface were given to prove the above mentioned algorithms, and the precision were ±2~±4 cm. The results show that the proposed algorithms based on single and double difference which are used for water level retrieval can sufficiently decrease the influences due to clock error, ionospheric and tropospheric error.

  10. The Allen Telescope Array Twenty-centimeter Survey -- A 700-Square-Degree, Multi-Epoch Radio Dataset -- II: Individual Epoch Transient Statistics

    CERN Document Server

    Croft, Steve; Keating, Garrett; Law, Casey; Whysong, David; Williams, Peter K G; Wright, Melvyn

    2011-01-01

    We present our second paper on the Allen Telescope Array Twenty-centimeter Survey (ATATS), a multi-epoch, ~700 sq. deg. radio image and catalog at 1.4 GHz. The survey is designed to detect rare, bright transients as well as to commission the ATA's wide-field survey capabilities. ATATS explores the challenges of multi-epoch transient and variable source surveys in the domain of dynamic range limits and changing (u,v) coverage. Here we present images made using data from the individual epochs, as well as a revised image combining data from all ATATS epochs. The combined image has RMS noise 3.96 mJy / beam, with a circular beam of 150 arcsec FWHM. The catalog, generated using a false detection rate algorithm, contains 4984 sources, and is >90% complete to 37.9 mJy. The catalogs generated from snapshot images of the individual epochs contain between 1170 and 2019 sources over the 564 sq. deg. area in common to all epochs. The 90% completeness limits of the single epoch catalogs range from 98.6 to 232 mJy. We comp...

  11. Past epochs of significantly higher pressure atmospheres on Pluto

    Science.gov (United States)

    Stern, S. A.; Binzel, R. P.; Earle, A. M.; Singer, K. N.; Young, L. A.; Weaver, H. A.; Olkin, C. B.; Ennico, K.; Moore, J. M.; McKinnon, W. B.; Spencer, J. R.; New Horizons Geology; Geophysics; Atmospheres Teams

    2017-05-01

    Pluto is known to have undergone thousands of cycles of obliquity change and polar precession. These variations have a large and corresponding impact on the total average solar insolation reaching various places on Pluto's surface as a function of time. Such changes could produce dramatic increases in surface pressure and may explain certain features observed by New Horizons on Pluto's surface, including some that indicate the possibility of surface paleo-liquids. This paper is the first to discuss multiple lines of geomorphological evidence consistent with higher pressure epochs in Pluto's geologic past, and it also the first to provide a mechanism for potentially producing the requisite high pressure conditions needed for an environment that could support liquids on Pluto. The presence of such liquids and such conditions, if borne out by future work, would fundamentally affect our view of Pluto's past climate, volatile transport, and geological evolution. This paper motivates future, more detailed climate modeling and geologic interpretation efforts in this area.

  12. Dipole of the Epoch of Reionization 21-cm signal

    CERN Document Server

    Slosar, Anže

    2016-01-01

    The motion of the solar system with respect to the cosmic rest frame modulates the monopole of the Epoch of Reionization 21-cm signal into a dipole. This dipole has a characteristic frequency dependence that is dominated by the frequency derivative of the monopole signal. We argue that although the signal is weaker by a factor of $\\sim200$, there are significant benefits in measuring the dipole. Most importantly, the direction of the cosmic velocity vector is known exquisitely well from the cosmic microwave background and is not aligned with the galaxy velocity vector that modulates the foreground monopole. Moreover, an experiment designed to measure a dipole can rely on differencing patches of the sky rather than making an absolute signal measurement, which helps with some systematic effects.

  13. Epoch-making milestones in antibiotic exploratory researches in Japan.

    Science.gov (United States)

    Hotta, Kunimoto

    2017-01-01

    Professor Satoshi Ōmura was awarded the 2015 Nobel Prize in Physiology or Medicine. He is the third to win the award for research on antibiotic, following Fleming' (UK, 1945, discovery of penicillin) and Waksman (USA, 1952, discovery of streptomycin), and the second person after Waksman to receive the award for research on actinomycetes. By focusing his research on macrolides stemming from leucomycin research rather than β-lactams like penicillin or aminoglycosides like streptomycin, Prof. Ōmura realized many scientific achievements. These efforts finally led to the discovery of avermectin and its semi-synthetic derivative, ivermectin, considered a monumental contribution to the human race. In this manuscript, I will outline the chronicles of the epoch-making antibiotic exploratory researches preceding Prof. Ōmura.

  14. Three epochs of EVN observations towards IRAS 23365+3604

    CERN Document Server

    Romero-Canizales, Cristina; Alberdi, Antxon

    2010-01-01

    The European VLBI Network (EVN) provides us with the necessary sensitivity and angular resolution to study the nuclear and circumnuclear regions in Luminous and Ultraluminous Infrared Galaxies. The high Star Formation Rates (SFR) inferred for these galaxies implies both the presence of a high number of massive stars and a dense surrounding medium. Therefore, bright radio SNe are expected to occur. With the aim of estimating the SFR in ULIRGs by means of Core Collapse supernova (CCSN) detections, we started an observing campaign with the EVN on a small sample of the brightest and farthest ULIRGs in the local Universe. We present here our results from three epochs of quasi-simultaneous observations with the EVN at 6 and 18 cm towards one of the objects in our sample: IRAS 23365+3604.

  15. Three epochs of EVN observations towards IRAS 23365+3604

    Science.gov (United States)

    Romero-Canizales, C.; Perez-Torres, M.; Alberdi, A.

    The European VLBI Network (EVN) provides us with the necessary sensitivity and angular resolution to study the nuclear and circumnuclear regions in Luminous and Ultraluminous Infrared Galaxies. The high Star Formation Rates (SFR) inferred for these galaxies implies both the presence of a high number of massive stars and a dense surrounding medium. Therefore, bright radio SNe are expected to occur. With the aim of estimating the SFR in ULIRGs by means of Core Collapse supernova (CCSN) detections, we started an observing campaign with the EVN on a small sample of the brightest and farthest ULIRGs in the local Universe. We present here our results from three epochs of quasi-simultaneous observations with the EVN at 6 and 18 cm towards one of the objects in our sample: IRAS 23365+3604.

  16. A NEOWISE Survey of Quasars in the Epoch of Reionization

    Science.gov (United States)

    Fan, Xiaohui

    Luminous quasars at high redshift provide direct probes of the evolution of supermassive black holes (BHs) and intergalactic medium (IGM) at early cosmic time. More than 100 quasars have now been discovered at z>6, with the highest redshift at z=7.1. Detections of such objects indicate the existence of billion solar mass BHs merely a few hundred Myrs after the first star formation in the universe, challenging the theory of BH growth and BH-galaxy coevolution at early epoch. Absorption spectra of the highest redshift quasars reveal complete Gunn-Peterson absorption from an increasing neutral IGM, marking the end of the reionization epoch at z>6. Combined with observations of CMB polarization and high-redshift Ly alpha galaxies, current data strongly suggest a peak of reionization activity and emergence of the earliest galaxies and AGNs at 77, and a handful at z>6.5. In this ADAP program, we will carry out the first comprehensive survey of z>=7 quasars, using a WISE-based selection algorithm, deep mid-IR photometry from coadded NEOWISE data and deep optical and near-IR photometry from new wide-field imaging surveys. We will select and follow-up quasar candidates over >20,000 deg^2 of high galactic latitude sky, aiming at finding 10-15 quasars at z>=7 in the next three years. There are two main technical components of our program. (1) WISE-based quasar selection. We have developed a highly successful selection method by combining WISE and optical/near-IR photometry to search for luminous quasars at z = 4.5-6.5, resulted in the discovery of the first known supermassive black holes with 10 billion solar mass BHs in the early universe. We will expand and optimize the algorithm for the redshift range of 6.5 measure the density of luminous quasars and their BH masses at z>=7, and place constraint on the existence of z>8 quasars. These measurements will test whether super-Eddington accretion or direct formation of intermediate-mass BHs are needed for early BH growth

  17. Epoch-based Application Collaboration for Sensing Data Analysis

    Institute of Scientific and Technical Information of China (English)

    HU Kan; LIU Yun-sheng; WEN Bing

    2008-01-01

    The application collaboration was addressed to provide energy-efficient data services for distributed sensing applications to collaboratively interacting to achieve a desired global objective not detectable by any single cluster. An epoch-based transaction model was proposed by using the concept of sphere of control (SoC), and a collaborative sensing application can be dynamically formed as a nested architecture composed of time-synchronized applications. By loosening the rigid constraints of ACID to adapt the requirements of sensor networks, the submission, rollback and consistency rules ware educed and a two-phrase submission protocol was designed. Finally, it was illustrated that the model is capable of providing an adaptive formal template for sensing application collaboration. Our performance evaluations show that by applying the two-phrase submission protocol, we can significantly improve the number of reported answers and response time, raise resource utilization, and reduce the energyconsumption and data loss.

  18. Investigating the earliest epochs of the Milky Way halo

    Science.gov (United States)

    Starkenburg, Else; Starkenburg

    2016-08-01

    Resolved stellar spectroscopy can obtain knowledge about chemical enrichment processes back to the earliest times, when the oldest stars were formed. In this contribution I will review the early (chemical) evolution of the Milky Way halo from an observational perspective. In particular, I will discuss our understanding of the origin of the peculiar abundance patterns in various subclasses of extremely metal-poor stars, taking into account new data from our abundance and radial velocity monitoring programs, and their implications for our understanding of the formation and early evolution of both the Milky Way halo and the satellite dwarf galaxies therein. I conclude by presenting the ``Pristine'' survey, a program on the Canada-France-Hawaii Telescope to study this intriguing epoch much more efficiently.

  19. Reproductive structures of Rhamnaceae from the Cerro del Pueblo (Late Cretaceous, Coahuila) and Coatzingo (Oligocene, Puebla) Formations, Mexico

    National Research Council Canada - National Science Library

    Calvillo-Canadell, Laura; Cevallos-Ferriz, Sergio R. S

    2007-01-01

    .... Coyoacan, 04510 México D.F., Mexico Recently discovered fossil flowers from the Cretaceous Cerro del Pueblo and flowers and fruits from the Oligocene Coatzingo Formations are assigned to the Rhamnaceae...

  20. Saddle-shaped reticulate Nummulites from Early Oligocene rocks of Khari area, SW Kutch, India

    Indian Academy of Sciences (India)

    S Sengupta; Sampa Sarkar; S Mukhopadhyay

    2011-04-01

    Saddle-shaped reticulate Nummulites from the Early Oligocene rocks of Khari area, SW Kutch, India is reported here for the first time. Unusual shape of this Nummulites is due to the curved nature of the coiling plane, indicating space constrained postembryonic test growth. With regular development of chambers, septa and septal filaments, the saddle-shaped Nummulites constitutes the third morphotype of N. cf. fichteli Michelotti form A. Other morphotypes of the species reported earlier include inflated lenticular and conical tests. Multiple morphotypes of N. cf. fichteli form A indicates varied test growth in response to substrate conditions. Morphological variability exhibited by N. cf. fichteli form A from Kutch and some Early Oligocene reticulate Nummulites from the Far East are comparable. This faunal suite is morphologically distinct from the contemporary reticulate Nummulites of the European localities.

  1. Cyclone trends constrain monsoon variability during Late Oligocene sea level highstands (Kachchh Basin, NW India)

    OpenAIRE

    Reuter, M.; W. E. Piller; M. Harzhauser; Kroh, A

    2013-01-01

    Important concerns about the consequences of climate change for India are the potential impact on tropical cyclones and the monsoon. Herein we present a sequence of fossil shell beds from the shallow-marine Maniyara Fort Formation (Kachcch Basin) as an indicator of tropical cyclone activity along the NW Indian coast during the Late Oligocene warming period (~27–24 Ma). Direct proxies providing information about the atmospheric circulation dynamics over the Indian subcontinent at this ...

  2. Cyclone trends constrain monsoon variability during late Oligocene sea level highstands (Kachchh Basin, NW India)

    OpenAIRE

    Reuter, M.; W. E. Piller; M. Harzhauser; Kroh, A

    2013-01-01

    Climate change has an unknown impact on tropical cyclones and the Asian monsoon. Herein we present a sequence of fossil shell beds from the shallow-marine Maniyara Fort Formation (Kachcch Basin) as a recorder of tropical cyclone activity along the NW Indian coast during the late Oligocene warming period (~ 27–24 Ma). Proxy data providing information about the atmospheric circulation dynamics over the Indian subcontinent at this time are important since it corresponds to a major climate reorga...

  3. Cyclone trends constrain monsoon variability during late Oligocene sea level highstands (Kachchh Basin, NW India

    Directory of Open Access Journals (Sweden)

    M. Reuter

    2013-09-01

    Full Text Available Climate change has an unknown impact on tropical cyclones and the Asian monsoon. Herein we present a sequence of fossil shell beds from the shallow-marine Maniyara Fort Formation (Kachcch Basin as a recorder of tropical cyclone activity along the NW Indian coast during the late Oligocene warming period (~ 27–24 Ma. Proxy data providing information about the atmospheric circulation dynamics over the Indian subcontinent at this time are important since it corresponds to a major climate reorganization in Asia that ends up with the establishment of the modern Asian monsoon system at the Oligocene–Miocene boundary. The vast shell concentrations are comprised of a mixture of parautochthonous and allochthonous assemblages indicating storm-generated sediment transport from deeper to shallow water during third-order sea level highstands. Three distinct skeletal assemblages were distinguished, each recording a relative storm wave base. (1 A shallow storm wave base is shown by nearshore molluscs, reef corals and Clypeaster echinoids; (2 an intermediate storm wave base depth is indicated by lepidocyclinid foraminifers, Eupatagus echinoids and corallinacean algae; and (3 a deep storm wave base is represented by an Amussiopecten bivalve-Schizaster echinoid assemblage. These wave base depth estimates were used for the reconstruction of long-term tropical storm intensity during the late Oligocene. The development and intensification of cyclones over the recent Arabian Sea is primarily limited by the atmospheric monsoon circulation and strength of the associated vertical wind shear. Therefore, since the topographic boundary conditions for the Indian monsoon already existed in the late Oligocene, the reconstructed long-term cyclone trends were interpreted to reflect monsoon variability during the initiation of the Asian monsoon system. Our results imply an active monsoon over the Eastern Tethys at ~ 26 Ma followed by a period of monsoon weakening during the

  4. Oligocene sharks from vicinity of Poljšica near Podnart, Slovenia

    Directory of Open Access Journals (Sweden)

    Vasja Mikuž

    2014-12-01

    Full Text Available Poljšica and surroundings are known for numerous interesting fossil remains. Among the rarest fossil remains are vertebrates, and in the Poljšica Oligocene these consist exclusively of fish remains. In this contribution are considered six teeth of sharks, five belonging to species Carcharias cuspidatus (Agassiz, 1843, except a single problematic tooth that can be attributed most probably to genus Cosmopolitodus.

  5. Palm leaves from the Late Oligocene sediments of Makum Coalfield, Assam, India

    Indian Academy of Sciences (India)

    Gaurav Srivastava; R C Mehrotra; Hugues Bauer

    2012-06-01

    Two new palm leaf impressions, cf. Iguanura wallichiana and Palmacites makumensis sp. nov. are described from the Makum Coalfield, Tinsukia District, Assam. They belong to the Tikak Parbat Formation being considered as Late Oligocene (Chattian 28–23 Myr) in age. Their presence, along with the other known fossil records indicates that CMMT (cold month mean temperature) was not less than 18°C with plenty of rainfall, in the region during the period of deposition.

  6. Oligocene marine Date Mussel from Plaznica brook near Poljšica, West Slovenia

    Directory of Open Access Journals (Sweden)

    Vasja Mikuž

    2006-06-01

    Full Text Available In paper the bivalve of species Lithophaga ornatissima (Mayer-Eymar, 1886 is described,found in a corallite in Oligocene beds of the Plaznica creek at Poljšica near Podnart.This is the first find of this litophaga species in Slovenia. In literature no finds of fossil date mussels are mentioned from surroundings of Polj{ica in Upper Carniola.

  7. A remarkable female cranium of the early Oligocene anthropoid Aegyptopithecus zeuxis (Catarrhini, Propliopithecidae)

    OpenAIRE

    Simons, Elwyn L.; Seiffert, Erik R.; Ryan, Timothy M.; Attia, Yousry

    2007-01-01

    The most complete and best-preserved cranium of a Paleogene anthropoid ever found, that of a small female of the early Oligocene (≈29–30 Ma) stem catarrhine species Aegyptopithecus zeuxis, was recovered from the Jebel Qatrani Formation (Fayum Depression, Egypt) in 2004. The specimen is that of a subadult and, in craniodental dimensions, is the smallest Aegyptopithecus individual known. High-resolution computed tomographic (microCT) scanning of the specimen's well preserved cranial vault confi...

  8. New fossil records of Ceratozamia (Zamiaceae, Cycadales from the European Oligocene and lower Miocene

    Directory of Open Access Journals (Sweden)

    Kvaček Zlatko

    2014-12-01

    Full Text Available New compression leaf material of Ceratozamia (Zamiaceae has been recognised in the European Cenozoic. A leaflet of Ceratozamia floersheimensis (Engelhardt Kvaček was recovered among unidentified material from the Oligocene of Trbovlje, former Trifail, Slovenia, housed in old collections of the Austrian Geological Survey, Vienna. It is similar in morphology and epidermal anatomy to other specimens previously studied from the lower Oligocene of Flörsheim, Germany and Budapest, Hungary. A fragmentary leaflet assigned to C. hofmannii Ettingsh. was recovered in the uppermost part of the Most Formation (Most Basin in North Bohemia, Czech Republic and dated by magnetostratigraphy and cyclostratigraphy to CHRON C5Cn.3n, that is, the latest early Miocene. It yielded excellently preserved epidermal structures, permitting confirmation of the generic affinity and a more precise comparison with this lower Miocene species previously known from Austria (Münzenberg, Leoben Basin and re-investigated earlier. Both the Oligocene and Miocene populations of Ceratozamia are based on isolated disarticulated leaflets matching some living representatives in the size and slender form of the leaflets. Such ceratozamias thrive today in extratropical areas near the present limits of distribution of the genus along the Sierra Madre Orientale in north-eastern Mexico, in particular C. microstrobila Vovides & J.D. Rees and others of the C. latifolia complex, as well as C. hildae G.P. Landry & M.C. Wilson (“bamboo cycad”. The occurrence of Ceratozamia suggests subtropical to warm-temperate, almost frostless climate and a high amount of precipitation. The accompanied fossil vegetation of both species corresponds well with the temperature regime. While the Oligocene species in Hungary probably thrived under sub-humid conditions, the remaining occurrences of fossil Ceratozamia were connected with humid evergreen to mixed-mesophytic forests.

  9. Evidence for an intra-Oligocene compressive event in the Marseille-Aubagne basins (SE France)

    Energy Technology Data Exchange (ETDEWEB)

    Villeneuve, M.; Nury, D.; Arihac, P.; Gartner, A.; Linnemann, U.; Pantaine, L.

    2016-10-01

    An Oligocene tectonic event has been suspected as the origin of thrusts and folds in several Oligocene troughs and basins of Provence, including the Marseille-Aubagne basins. Deformations are generally assumed to be to a post Oligocene extensional event. The Marseille-Aubagne basins are geographically and stratigraphically separated into three basins (Jarret, Prado and Aubagne) with each of them exhibiting their own sedimentary succession. However, each of the successions includes two main units: - The lower unit which includes several formations attributed to the Rupelian age. All of these sediments are strongly or slightly deformed depending on their location with respect to the main faults. - The upper unit which includes formations of mainly Chattian age. They are undeformed or slightly deformed. Geological sections across the southern Prado basin show a succession of anticlines and synclines. Additionally the thrusting of the Carpiagne massif over the Prado basin has been evidenced since 1952. These deformations are here related to a compressional event According to palaeontological data, the latest deformed strata are ascribed to the Late Rupelian, whereas the earliest undeformed strata are ascribed to the Latest Rupelian. This is in accordance with age determinations on detrital zircons extracted from the latest deformed sandstone, and from the youngest age of detrital zircons from the undeformed sandstone. Thus, the stratigraphic limit between the deformed and undeformed formations should be set around the Rupelian / Chattian limit (28.1 Ma) according to the latest chronostratigraphic chart. Finally, we discuss correlations with similar events occurring around the Mediterranean area. (Author)

  10. Heterogeneity in global vegetation and terrestrial climate change during the late Eocene to early Oligocene transition

    Science.gov (United States)

    Pound, Matthew J.; Salzmann, Ulrich

    2017-02-01

    Rapid global cooling at the Eocene – Oligocene Transition (EOT), ~33.9–33.5 Ma, is widely considered to mark the onset of the modern icehouse world. A large and rapid drop in atmospheric pCO2 has been proposed as the driving force behind extinctions in the marine realm and glaciation on Antarctica. However, the global terrestrial response to this cooling is uncertain. Here we present the first global vegetation and terrestrial temperature reconstructions for the EOT. Using an extensive palynological dataset, that has been statistically grouped into palaeo-biomes, we show a more transitional nature of terrestrial climate change by indicating a spatial and temporal heterogeneity of vegetation change at the EOT in both hemispheres. The reconstructed terrestrial temperatures show for many regions a cooling that started well before the EOT and continued into the Early Oligocene. We conclude that the heterogeneous pattern of global vegetation change has been controlled by a combination of multiple forcings, such as tectonics, sea-level fall and long-term decline in greenhouse gas concentrations during the late Eocene to early Oligocene, and does not represent a single response to a rapid decline in atmospheric pCO2 at the EOT.

  11. Heterogeneity in global vegetation and terrestrial climate change during the late Eocene to early Oligocene transition.

    Science.gov (United States)

    Pound, Matthew J; Salzmann, Ulrich

    2017-02-24

    Rapid global cooling at the Eocene - Oligocene Transition (EOT), ~33.9-33.5 Ma, is widely considered to mark the onset of the modern icehouse world. A large and rapid drop in atmospheric pCO2 has been proposed as the driving force behind extinctions in the marine realm and glaciation on Antarctica. However, the global terrestrial response to this cooling is uncertain. Here we present the first global vegetation and terrestrial temperature reconstructions for the EOT. Using an extensive palynological dataset, that has been statistically grouped into palaeo-biomes, we show a more transitional nature of terrestrial climate change by indicating a spatial and temporal heterogeneity of vegetation change at the EOT in both hemispheres. The reconstructed terrestrial temperatures show for many regions a cooling that started well before the EOT and continued into the Early Oligocene. We conclude that the heterogeneous pattern of global vegetation change has been controlled by a combination of multiple forcings, such as tectonics, sea-level fall and long-term decline in greenhouse gas concentrations during the late Eocene to early Oligocene, and does not represent a single response to a rapid decline in atmospheric pCO2 at the EOT.

  12. Tibetan plateau aridification linked to global cooling at the Eocene-Oligocene transition.

    Science.gov (United States)

    Dupont-Nivet, Guillaume; Krijgsman, Wout; Langereis, Cor G; Abels, Hemmo A; Dai, Shuang; Fang, Xiaomin

    2007-02-08

    Continental aridification and the intensification of the monsoons in Asia are generally attributed to uplift of the Tibetan plateau and to the land-sea redistributions associated with the continental collision of India and Asia, whereas some studies suggest that past changes in Asian environments are mainly governed by global climate. The most dramatic climate event since the onset of the collision of India and Asia is the Eocene-Oligocene transition, an abrupt cooling step associated with the onset of glaciation in Antarctica 34 million years ago. However, the influence of this global event on Asian environments is poorly understood. Here we use magnetostratigraphy and cyclostratigraphy to show that aridification, which is indicated by the disappearance of playa lake deposits in the northeastern Tibetan plateau, occurred precisely at the time of the Eocene-Oligocene transition. Our findings suggest that this global transition is linked to significant aridification and cooling in continental Asia recorded by palaeontological and palaeoenvironmental changes, and thus support the idea that global cooling is associated with the Eocene-Oligocene transition. We show that, with sufficient age control on the sedimentary records, global climate can be distinguished from tectonism and recognized as a major contributor to continental Asian environments.

  13. Hummingbird with modern feathering: an exceptionally well-preserved Oligocene fossil from southern France

    Science.gov (United States)

    Louchart, Antoine; Tourment, Nicolas; Carrier, Julie; Roux, Thierry; Mourer-Chauviré, Cécile

    2008-02-01

    Hummingbirds (Trochilidae) today have an exclusively New World distribution, but their pre-Pleistocene fossil record comes from Europe only. In this study, we describe an exceptionally preserved fossil hummingbird from the early Oligocene of southeastern France. The specimen is articulated, with a completely preserved beak and feathering. Osteological characters allow to identify it as Eurotrochilus sp. This genus is a stem group representative of Trochilidae and was recently described from the early Oligocene of southern Germany. The new fossil reveals that these European Trochilidae were remarkably modern in size, skeletal proportions and the shape of the wing, tail and beak and hyoid bones. These features confirm the early acquisition of the abilities of hovering and nectarivory in hummingbirds, probably before the Oligocene. In several morphological characteristics, they resemble members of the ‘true hummingbirds’ (subfamily Trochilinae) and differ from hermits (Phaethornithinae). These features, which include a short and square tail and a moderately long, almost straight beak, appear to be primitive within the family Trochilidae.

  14. Oligocene biogenic siliceous deposits on the slope of the northern South China Sea

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The abundance of radiolarian, diatom and sponge spicule and H4SiO4 in pore-waters increase abruptly at the boundary between Early and Late Oligocene (about 30-27.5 Ma) at Site 1148 of the northern South China Sea (SCS), indicating high biogenic silica accumulation during this time. At the same time (about 30-28 Ma), high biogenic silica deposition occurred in the cen tral equatorial Pacific. Comparison of the biogenic silica accumulation at Site 1148 of the SCS with that at Site 929 of the Atlantic verifies that the biogenic silica accumulation between the low lati tude Pacific and Atlantic oceans expresses the evident relationship of compensation during theOligocene. Biogenic silica accumulation decreased in the Atlantic, whereas it increased in the Pa cific at the boundary between the Early and Late Oligocene. It resulted from the formation and presence of North Atlantic deep water (NADW) in the Atlantic basin, indicating an intensive basin-basin fractionation. XRD analysis and SEM observation of the samples from Site 1148 demon strate that most of radiolarian, diatom and sponge spicule have suffered from dissolution and reprecipitation, suggested by the opal-A→opal-CT transformation. As a result of the transformation,porosity increased, but dry and bulk densities decreased, reflecting the consequence of diagenesis on the physical property of sediment.

  15. Cumulative light from the Epoch of Reionization - the Near Infrared Background and the 21cm line.

    NARCIS (Netherlands)

    Fernandez, Elizabeth R.; Zaroubi, Saleem; Iliev, Ilian T.

    2014-01-01

    Observations of the Epoch of Reionization are now becoming a distinct possibility. High-redshift galaxy surveys are discovering galaxies well into the Epoch of Reionization. However, these observations present a small portion of the total picture, providing information on only the brightest objects

  16. Linguistic Engineering and Linguistic of Engineering: Adaptation of Linguistic Paradigm for Circumstance of Engineering Epoch

    OpenAIRE

    Natalya Halina

    2014-01-01

    The article is devoted to the problems of linguistic knowledge in the Engineering Epoch. Engineering Epoch is the time of adaptation to the information flows by knowledge management, The system of adaptation mechanisms is connected with linguistic and linguistic technologies, forming in new linguistic patterns Linguistic Engineering and Linguistic of Engineering.

  17. Faint Object Detection in Multi-Epoch Observations via Catalog Data Fusion

    CERN Document Server

    Budavari, Tamas; Loredo, Thomas J

    2016-01-01

    Observational astronomy in the time-domain era faces several new challenges. One of them is the efficient use of observations obtained at multiple epochs. The work presented here addresses faint object detection with multi-epoch data, and describes an incremental strategy for separating real objects from artifacts in ongoing surveys, in situations where the single-epoch data are summaries of the full image data, such as single-epoch catalogs of flux and direction estimates for candidate sources. The basic idea is to produce low-threshold single-epoch catalogs, and use a probabilistic approach to accumulate catalog information across epochs; this is in contrast to more conventional strategies based on co-added or stacked image data across all epochs. We adopt a Bayesian approach, addressing object detection by calculating the marginal likelihoods for hypotheses asserting there is no object, or one object, in a small image patch containing at most one cataloged source at each epoch. The object-present hypothesi...

  18. Systematic Uncertainties in Black Hole Masses Determined from Single Epoch Spectra

    DEFF Research Database (Denmark)

    Denney, Kelly D.; Peterson, Bradley M.; Dietrich, Matthias

    2008-01-01

    We explore the nature of systematic errors that can arise in measurement of black hole masses from single-epoch spectra of active galactic nuclei (AGNs) by utilizing the many epochs available for NGC 5548 and PG1229+204 from reverberation mapping databases. In particular, we examine systematics due...

  19. A CENTRAL LIMIT THEOREM FOR STRONG NEAR-EPOCH DEPENDENT RANDOM VARIABLES

    Institute of Scientific and Technical Information of China (English)

    LIN ZHENGYAN; QIU JIN

    2004-01-01

    In this paper, a central limit theorem for strong near-epoch dependent sequences of random variables introduced in [9] is showed. Under the same moments condition,the authors essentially weaken the "size" requirement mentioned in other papers about near epoch dependence.

  20. The “Anthropocene” epoch: Scientific decision or political statement?

    Science.gov (United States)

    Finney, Stanley C.; Edwards, Lucy E.

    2016-01-01

    The proposal for the “Anthropocene” epoch as a formal unit of the geologic time scale has received extensive attention in scientific and public media. However, most articles on the Anthropocene misrepresent the nature of the units of the International Chronostratigraphic Chart, which is produced by the International Commission on Stratigraphy (ICS) and serves as the basis for the geologic time scale. The stratigraphic record of the Anthropocene is minimal, especially with its recently proposed beginning in 1945; it is that of a human lifespan, and that definition relegates considerable anthropogenic change to a “pre-Anthropocene.” The utility of the Anthropocene requires careful consideration by its various potential users. Its concept is fundamentally different from the chronostratigraphic units that are established by ICS in that the documentation and study of the human impact on the Earth system are based more on direct human observation than on a stratigraphic record. The drive to officially recognize the Anthropocene may, in fact, be political rather than scientific.

  1. Prospects for detecting CII emission during the Epoch of Reionization

    CERN Document Server

    Silva, Marta B; Cooray, Asantha; Gong, Yan

    2014-01-01

    We produce simulations of emission of the atomic CII line in large sky fields in order to determine the current prospects for mapping this line during the high redshift Epoch of Reionization. We estimate the CII line intensity, redshift evolution and spatial fluctuations using observational relations between CII emission and the SFR in a galaxy for the frequency range of 200 GHz to 300 GHz. We obtained a frequency averaged intensity of CII emission of ${\\rm I_{\\rm CII}=(4 \\pm 2)\\times10^{2}\\, Jy\\, \\rm sr^{-1}}$ in the redshift range $z\\, \\sim\\, 5.3\\, -\\, 8.5$. Observations of CII emission in this frequency range will suffer contamination from emission lines at lower redshifts, in particular from the CO rotation lines. For the relevant frequency range we estimated the CO contamination (originated in emission from galaxies at $z\\, <\\, 2.5$), using simulations, to be ${\\rm I_{\\rm CO} \\approx 10^{3}\\, Jy \\, sr^{-1}}$ and independently confirmed the result based in observational relations. We generated maps as ...

  2. Exploring a Massive Starburst in the Epoch of Reionization

    Science.gov (United States)

    Marrone, Daniel; Aravena, M.; Chapman, S.; De Breuck, C.; Gonzalez, A.; Hezavehe, S.; Litke, K.; Ma, J.; Malkan, M.; Spilker, J.; Stalder, B.; Stark, D.; Strandet, M.; Tang, M.; Vieira, J.; Weiss, A.; Welikala, N.

    2016-08-01

    We request deep multi-band imaging of a unique dusty galaxy in the Epoch of Reionization (EoR), selected via its millimeter-wavelength dust emission in the 2500-square-degree South Pole Telescope survey. Spectroscopically confirmed to lie at z=6.900, this galaxy has a large dust mass and is likely one of the most rapidly star-forming objects in the EoR. Using Gemini-S, we have identified z-band emission from this object that could be UV continuum emission at z=6.9 or from a foreground lens. Interpretation of this object, and a complete understanding of its meaning for the census of star formation in the EoR, requires that we establish the presence or absence of gravitational lensing. The dust mass observed in this source is also unexpectedly large for its era, and measurements of the assembled stellar population, through the UV-continuum slope and restframe optical color, will help characterize the stellar mass and dust properties in this very early galaxy, the most spectacular galaxy yet discovered by the SPT.

  3. Foreground simulations for the LOFAR - Epoch of Reionization Experiment

    CERN Document Server

    Jelic, Vibor; Labropoulos, Panagiotis; Thomas, Rajat M; Bernardi, Gianni; Brentjens, Michiel; de Bruyn, Ger; Ciardi, Benedetta; Harker, Geraint; Koopmans, Leon V E; Pandey, Vishambhar; Schaye, Joop; Yatawatta, Sarod

    2008-01-01

    Future high redshift 21-cm experiments will suffer from a high degree of contamination, due both to astrophysical foregrounds and to non-astrophysical and instrumental effects. In order to reliably extract the cosmological signal from the observed data, it is essential to understand very well all data components and their influence on the extracted signal. Here we present simulated astrophysical foregrounds datacubes and discuss their possible statistical effects on the data. The foreground maps are produced assuming 5 deg x 5 deg windows that match those expected to be observed by the LOFAR Epoch-of-Reionization (EoR) key science project. We show that with the expected LOFAR-EoR sky and receiver noise levels, which amount to ~52 mK at 150 MHz after 300 hours of total observing time, a simple polynomial fit allows a statistical reconstruction of the signal. We also show that the polynomial fitting will work for maps with realistic yet idealised instrument response, i.e., a response that includes only a unifor...

  4. Thinking social sciences from Latin America at the epochal change

    Directory of Open Access Journals (Sweden)

    Jaime Antonio Preciado Coronado

    2016-07-01

    Full Text Available From the legacy of an original disciplinary approach, as the Dependence theory and its Marxian critics, or the neo-structural economic theory founded by The Economic Commission for Latin America (ECLA, the Latin-American social sciences deny the Anglo-European centered approaches, in the way of reaffirming its own critical thinking, including the neo-colonial practices. The challenge for this critical thinking is to be, simultaneously, cosmopolitan and Latin American’s one. In this process, the Latin-American social thinking is regaining its own originality and its vigorous proposals, thanks to a rich south-south dialogue, that implies a global character of its reflections and the questioning of its universal references. Although neither classical nor western Marxism are hegemonic within critical theory, the (neo Marxism enriched with criticism of the coloniality of power, the theory of World-System, critical geopolitics and political ecology recover the field of critical theory in key founder of an epochal thinking time. Epistemological debates with post-structuralism and postmodern approaches configure various recent developments in critical theory

  5. Bayesian Single-Epoch Photometric Classification of Supernovae

    CERN Document Server

    Poznanski, D; Gal-Yam, A; Poznanski, Dovi; Maoz, Dan; Gal-Yam, Avishay

    2006-01-01

    (abridged) Ongoing supernova (SN) surveys find hundreds of candidates, that require confirmation for their use. Traditional classification based on followup spectroscopy of all candidates is virtually impossible for these large samples. We present an automatic Bayesian classifying algorithm for supernovae, the SN-ABC. We rely solely on single-epoch multiband photometry and host-galaxy (photometric) redshift information to sort SN candidates into the two major types, Ia and core-collapse supernovae. We test the SN-ABC performance on published samples of SNe from the SNLS and GOODS projects that have both broad-band photometry and spectroscopic classification (so the true type is known). The SN-ABC correctly classifies up to 97% (85%) of the type Ia (II-P) SNe in SNLS, and similar fractions of the GOODS SNe, depending on photometric redshift quality. We further test our method on large artificial samples to explore possible biases, and find that, in deep surveys, SNe Ia are best classified at redshifts z >~ 0.6...

  6. Galactic Outflows and Photoionization Heating in the Reionization Epoch

    CERN Document Server

    Finlator, K; Özel, F

    2011-01-01

    We carry out a new suite of cosmological radiation hydrodynamic simulations and explore the relative impacts on reionization-epoch star formation of galactic outflows and photoionization heating. By itself, an extragalactic ultraviolet background (EUVB) suppresses the luminosity function by less than 50% at z=6, overproducing the observed galaxy abundance by a factor of 3-5. Galactic outflows restore agreement with observations without preventing Population II star formation from reionizing the Universe by z=6. The resulting EUVB suppresses star formation in halos with virial temperatures below 10^5K but has a weaker impact in more massive halos. Nonetheless, the low-mass halos contribute up to 50% of all ionizing photons owing to the EUVB's inhomogeneity. Overall, star formation rate scales as halo mass M_h to the 1.3-1.4 in halos with $M_h=10^{8.2--10.2}\\msun$. This is a steeper dependence than is often assumed in reionization models, boosting the expected power spectrum of 21 centimeter fluctuations on lar...

  7. A dusty, normal galaxy in the epoch of reionization

    CERN Document Server

    Watson, Darach; Knudsen, Kirsten Kraiberg; Richard, Johan; Gallazzi, Anna; Michałowski, Michał Jerzy

    2015-01-01

    Candidates for the modest galaxies that formed most of the stars in the early universe, at redshifts $z > 7$, have been found in large numbers with extremely deep restframe-UV imaging. But it has proved difficult for existing spectrographs to characterise them in the UV. The detailed properties of these galaxies could be measured from dust and cool gas emission at far-infrared wavelengths if the galaxies have become sufficiently enriched in dust and metals. So far, however, the most distant UV-selected galaxy detected in dust emission is only at $z = 3.25$, and recent results have cast doubt on whether dust and molecules can be found in typical galaxies at this early epoch. Here we report thermal dust emission from an archetypal early universe star-forming galaxy, A1689-zD1. We detect its stellar continuum in spectroscopy and determine its redshift to be $z = 7.5\\pm0.2$ from a spectroscopic detection of the Ly{\\alpha} break. A1689-zD1 is representative of the star-forming population during reionisation, with ...

  8. Observations of the first light and the epoch of reionization

    Institute of Scientific and Technical Information of China (English)

    Xiaohui Fan

    2012-01-01

    Studying the first generation of stars,galaxies and supermassive black holes as well as the epoch of reionization is one of the fundamental questions of modern astrophysics.The last few years have witnessed the first confirmation of the discoveries of galaxies,quasars and Gamma-Ray Bursts at z > 7,with possible detections at z ~ 10.There is also mounting evidence that cosmic reionization is a prolonged process that peaks around z ~ 10 and ends at z ~ 6 - 7.Observations of the highest redshift intergalactic medium and the most metal-poor stars in the Galaxy begin to constrain the earliest chemical enrichment processes in the Universe.These observations provide a glimpse of cosmic history over the first billion years after the Big Bang.In this review,we will present recent results on the observations of the high-redshift Universe over the past decade,highlight key challenges and uncertainties in these observations,and preview what is possible with the next generation facilities in studying the first light and mapping the history of reionization.

  9. 'Super-Chandrasekhar' Type Ia Supernovae at nebular epochs

    CERN Document Server

    Taubenberger, Stefan; Hachinger, Stephan; Mazzali, Paolo A; Benetti, Stefano; Nugent, Peter E; Scalzo, Richard A; Pakmor, Rüdiger; Stanishev, Vallery; Spyromilio, Jason; Bufano, Filomena; Sim, Stuart A; Leibundgut, Bruno; Hillebrandt, Wolfgang

    2013-01-01

    We present a first systematic comparison of superluminous Type Ia supernovae (SNe Ia) at late epochs, including previously unpublished photometric and spectroscopic observations of SN 2007if, SN 2009dc and SNF20080723-012. Photometrically, the objects of our sample show a diverse late-time behaviour, some of them fading quite rapidly after a light-curve break at ~150-200d. The latter is likely the result of flux redistribution into the infrared, possibly caused by dust formation, rather than a true bolometric effect. Nebular spectra of superluminous SNe Ia are characterised by weak or absent [Fe III] emission, pointing at a low ejecta ionisation state as a result of high densities. To constrain the ejecta and 56Ni masses of superluminous SNe Ia, we compare the observed bolometric light curve of SN 2009dc with synthetic model light curves, focusing on the radioactive tail after ~60d. Models with enough 56Ni to explain the light-curve peak by radioactive decay, and at the same time sufficient mass to keep the e...

  10. Revisiting The First Galaxies: The Epoch of Population III Stars

    Science.gov (United States)

    Muratov, Alexander; Gnedin, O. Y.; Gnedin, N. Y.; Zemp, M. K.

    2013-01-01

    We study the formation of the first galaxies using new hydrodynamic cosmological simulations with the ART code. Our simulations feature a recently developed model for dust-based formation of molecular gas. Here, we develop and implement a new recipe for the formation of metal-free Pop III stars. We reach a spatial resolution of 2 pc at z=10 and resolve star-forming galaxies with the masses above 10^6 solar masses. We find the epoch during which Pop III stars dominate the energy and metal budget of the universe to be short-lived. While these stars seed their host galaxies with metals, they cannot drive significant outflows to enrich the IGM in our simulations. Feedback from pair instability supernovae causes Pop III star formation to self-terminate within their host galaxies, but is not strong enough to suppress star formation in external galaxies. Within any individual galaxy, Pop II stars overtake Pop III stars within ~50-150 Myr. A threshold of M = 3 * 10^6 solar masses separates galaxies that lose a significant fraction of their baryons due to Pop III feedback from those that do not. Understanding the nature of the transition between Pop III and Pop II star formation is of key importance for studying the dawn of galaxy formation.

  11. Large Scale Structure in the Epoch of Reionization

    Science.gov (United States)

    Koekemoer, Anton; Mould, Jeremy; Cooke, Jeffrey; Wyithe, Stuart; Lidman, Christopher; Trenti, Michele; Abbott, Tim; Kunder, Andrea; Barone-Nugent, Robert; Tescari, Edoardo; Katsianis, Antonios

    2014-02-01

    We propose to capitalize on the high red sensitivity and large field of view of DECam to detect the brightest and rarest galaxies at z=6-7. Our 2012 results show the signature of large scale structure with wavenumber of order 0.1 inverse Mpc in line with expectations of primordial non-gaussianity. But the signal to noise in one deep field from two nights' data is insufficient for a robust conclusion. Ten nights' data will do the job. These data will also constrain the galaxy contribution to reionization by enabling a tighter constraint on the full galaxy luminosity function, including the faint end. The observations will be executed with a cadence and depth that will enable the detection of super-luminous supernovae at z=6-7. Super-luminous supernovae are a recently observed class of supernovae that are 10-100x more luminous than typical supernovae. This class includes pair- instability supernovae that are a rare, third type of supernova explosion in which only 3 events are known. The proposed observations will greatly extend the current reach of supernovae research, examining their occurrence rate and properties near the epoch of reionization.

  12. Atlas Basemaps in Web 2.0 Epoch

    Science.gov (United States)

    Chabaniuk, V.; Dyshlyk, O.

    2016-06-01

    The authors have analyzed their experience of the production of various Electronic Atlases (EA) and Atlas Information Systems (AtIS) of so-called "classical type". These EA/AtIS have been implemented in the past decade in the Web 1.0 architecture (e.g., National Atlas of Ukraine, Atlas of radioactive contamination of Ukraine, and others). One of the main distinguishing features of these atlases was their static nature - the end user could not change the content of EA/AtIS. Base maps are very important element of any EA/AtIS. In classical type EA/AtIS they were static datasets, which consisted of two parts: the topographic data of a fixed scale and data of the administrative-territorial division of Ukraine. It is important to note that the technique of topographic data production was based on the use of direct channels of topographic entity observation (such as aerial photography) for the selected scale. Changes in the information technology of the past half-decade are characterized by the advent of the "Web 2.0 epoch". Due to this, in cartography appeared such phenomena as, for example, "neo-cartography" and various mapping platforms like OpenStreetMap. These changes have forced developers of EA/AtIS to use new atlas basemaps. Our approach is described in the article. The phenomenon of neo-cartography and/or Web 2.0 cartography are analysed by authors using previously developed Conceptual framework of EA/AtIS. This framework logically explains the cartographic phenomena relations of three formations: Web 1.0, Web 1.0x1.0 and Web 2.0. Atlas basemaps of the Web 2.0 epoch are integrated information systems. We use several ways to integrate separate atlas basemaps into the information system - by building: weak integrated information system, structured system and meta-system. This integrated information system consists of several basemaps and falls under the definition of "big data". In real projects it is already used the basemaps of three strata: Conceptual

  13. A dusty, normal galaxy in the epoch of reionization.

    Science.gov (United States)

    Watson, Darach; Christensen, Lise; Knudsen, Kirsten Kraiberg; Richard, Johan; Gallazzi, Anna; Michałowski, Michał Jerzy

    2015-03-19

    Candidates for the modest galaxies that formed most of the stars in the early Universe, at redshifts z > 7, have been found in large numbers with extremely deep restframe-ultraviolet imaging. But it has proved difficult for existing spectrographs to characterize them using their ultraviolet light. The detailed properties of these galaxies could be measured from dust and cool gas emission at far-infrared wavelengths if the galaxies have become sufficiently enriched in dust and metals. So far, however, the most distant galaxy discovered via its ultraviolet emission and subsequently detected in dust emission is only at z = 3.2 (ref. 5), and recent results have cast doubt on whether dust and molecules can be found in typical galaxies at z ≥ 7. Here we report thermal dust emission from an archetypal early Universe star-forming galaxy, A1689-zD1. We detect its stellar continuum in spectroscopy and determine its redshift to be z = 7.5 ± 0.2 from a spectroscopic detection of the Lyman-α break. A1689-zD1 is representative of the star-forming population during the epoch of reionization, with a total star-formation rate of about 12 solar masses per year. The galaxy is highly evolved: it has a large stellar mass and is heavily enriched in dust, with a dust-to-gas ratio close to that of the Milky Way. Dusty, evolved galaxies are thus present among the fainter star-forming population at z > 7.

  14. Characterizing RR Lyraes using SDSS, Single-Epoch Spectroscopy

    Science.gov (United States)

    Long, Stacy Scott; Wilhelm, Ronald J.; De Lee, Nathan M.

    2017-01-01

    Starting with Data Release-7, the Sloan Digital Sky Survey (SDSS) has made available the single-epoch spectra (SES) that were previously combined to produce the final composite spectra available for stars and galaxies. These SES can be used to probe time-variability through spectral line strength variations. RR Lyrae stars (RRL) have typically been identified using periodic variations in their light curves. Today, using the SDSS-SES it is possible to, in some cases, identify RRL from changes in the line strengths of the Ca-IIK, H-$\\beta$, H-$\\gamma$, and H-$\\delta$ lines. Similarly, it is possible to construct composite spectra that are free of phase-blending, by grouping SES that have similar spectral line strengths, for an individual star. We have developed a method for comparing SES with synthetic spectra spanning a range of T = [5500,8500]K, log g = [1.0-4.0] and [Fe/H]=[-3.0-0.0] to produce temperatures, surface gravities and metallicities for all SES taken for a given star. Using this method we are able to search for variations in temperature that are 2-sigma beyond the computed uncertainty, indicating that spectral variation is occurring. We will show results using a sample of bright RRL stars of known pulsation phase and stars from SDSS-Stripe82 which have published light curves for several hundred RRLs. We will also present a temperature-phase diagram that shows stars with consistent phases can be produced allowing us to construct composite spectra that are of the same phase for a given star. This is crucially important to the accurate determination of metal abundance for stars in the SDSS spectral foot-print. We will also show details of the compiled Catalina Surveys for stars with SDSS spectroscopy.

  15. Atmospheric CO2 from the late Oligocene to early Miocene reconstructed from photosynthesis data and leaf characteristics of fossil plants

    Science.gov (United States)

    Grein, Michaela; Oehm, Christoph; Konrad, Wilfried; Utescher, Torsten; Kunzmann, Lutz; Roth-Nebelsick, Anita

    2013-04-01

    In the Cenozoic era, global climate changed from greenhouse to icehouse conditions. During the Oligocene, the comparatively cool phase in the earlier part of the late Oligocene is followed by the Late Oligocene Warming and a major glaciation event at the Oligocene-Miocene transition (Mi-1). Various studies indicate that these climate events were coupled to changes in atmospheric CO2 levels. In this study, atmospheric CO2 from the late Oligocene to the early Miocene was reconstructed by using photosynthesis data and fossil leaf characteristics. We used plant material from various sites located in Germany and Austria comprising fossil leaves of four angiosperm plant species: Platanus neptuni (Platanaceae), Quercus rhenana, Q. praerhenana and Eotrigonobalanus furcinervis (all Fagaceae). A mechanistic-theoretical approach based on stomatal parameters, photosynthesis data and gas exchange parameters was applied to model palaeoatmospheric CO2 levels. Detailed climate data of the considered sites were reconstructed as well since the mechanistic-theoretical approach requires climate data as input parameters for calculating both assimilation rate and transpiration rate. Our results indicate a steady CO2 level of about 400 ppm for all sites and therefore suggest a decoupling of CO2 and cooling/warming events for the considered time slices.

  16. Gas accumulations in Oligocene-Miocene reservoirs in the Alpine Foreland Basin (Austria): evidence for gas mixing and gas degradation

    Science.gov (United States)

    Pytlak, L.; Gross, D.; Sachsenhofer, R. F.; Bechtel, A.; Linzer, H.-G.

    2016-11-01

    Two petroleum systems are present in the eastern (Austrian) sector of the Alpine Foreland Basin. Whereas oil and thermogenic gas in Mesozoic and Eocene reservoir rocks have been generated beneath the Alps in Lower Oligocene source rocks, relative dry gas in Oligocene-Miocene clastic rocks deposited in the deep marine basin-axial channel system (Puchkirchen Channel) is interpreted as microbial in origin. Detailed investigations of the molecular and isotope composition of 87 gas samples from 86 wells, representing all producing fields with Oligocene and Miocene reservoir rocks, suggest that the presence of pure microbial gas is rare and limited mainly to the northern basin flank (e.g., KK field). All other fields contain varying amounts of thermogenic gas, which has been generated from a source rock with oil-window maturity. A relation with the underlying thermogenic petroleum system is obvious. Upward migration occurred along discrete fault zones (e.g., H field) or through low-permeability caprocks. Local erosion of Lower Oligocene sediments, the principal seal for the thermogenic petroleum system, as well as a high percentage of permeable rocks within the Puchkirchen Channel favored upward migration and mixing of thermogenic and microbial gas. All gas samples in Oligocene-Miocene reservoirs are biodegraded. Biodegradation and the formation of secondary microbial gas resulted in gas drying. Therefore, the gas samples analyzed in this study are relative dry, despite significant contributions of thermogenic hydrocarbons. Biodegradation probably continues at present time. The degree of biodegradation, however, decreases with depth.

  17. The Late Oligocene to Early Miocene early evolution of rifting in the southwestern part of the Roer Valley Graben

    Science.gov (United States)

    Deckers, Jef

    2016-06-01

    The Roer Valley Graben is a Mesozoic continental rift basin that was reactivated during the Late Oligocene. The study area is located in the graben area of the southwestern part of the Roer Valley Graben. Rifting initiated in the study area with the development of a large number of faults in the prerift strata. Some of these faults were rooted in preexisting zones of weakness in the Mesozoic strata. Early in the Late Oligocene, several faults died out in the study area as strain became focused upon others, some of which were able to link into several-kilometer-long systems. Within the Late Oligocene to Early Miocene northwestward prograding shallow marine syn-rift deposits, the number of active faults further decreased with time. A relatively strong decrease was observed around the Oligocene/Miocene boundary and represents a further focus of strain onto the long fault systems. Miocene extensional strain was not accommodated by further growth, but predominantly by displacements along the long fault systems. Since the Oligocene/Miocene boundary coincides with a radical change in the European intraplate stress field, the latter might have contributed significantly to the simultaneous change of fault kinematics in the study area.

  18. Cyclone trends constrain monsoon variability during Late Oligocene sea level highstands (Kachchh Basin, NW India

    Directory of Open Access Journals (Sweden)

    M. Reuter

    2013-01-01

    Full Text Available Important concerns about the consequences of climate change for India are the potential impact on tropical cyclones and the monsoon. Herein we present a sequence of fossil shell beds from the shallow-marine Maniyara Fort Formation (Kachcch Basin as an indicator of tropical cyclone activity along the NW Indian coast during the Late Oligocene warming period (~27–24 Ma. Direct proxies providing information about the atmospheric circulation dynamics over the Indian subcontinent at this time are important since it corresponds to a major climate reorganization in Asia that ends up with the establishment of the modern Asian monsoon system in the Early Miocene. The vast shell concentrations comprise a mixture of parautochthonous and allochthonous assemblages indicating storm-generated sediment transport from deep to shallow water during third-order sea level highstands. Three distinct skeletal assemblages were distinguished each recording a relative storm wave base depth. (1 A shallow storm wave base is shown by nearshore mollusks, corals and Clypeaster echinoids; (2 an intermediate storm wave base depth is indicated by lepidocyclind foraminifers, Eupatagus echinoids and corallinaceans; and (3 a deep storm wave base is represented by an Amussiopecten–Schizaster echinoid assemblage. Vertical changes in these skeletal associations give evidence of gradually increasing tropical cyclone intensity in line with third-order sea level rise. The intensity of cyclones over the Arabian Sea is primarily linked to the strength of the Indian monsoon. Therefore and since the topographic boundary conditions for the Indian monsoon already existed in the Late Oligocene, the longer-term cyclone trends were interpreted to reflect monsoon variability during the initiation of the Asian monsoon system. Our results imply an active monsoon over the Eastern Tethys at ~26 Ma followed by a period of monsoon weakening during the peak of the Late Oligocene

  19. Correlating Mediterranean shallow water deposits with global Oligocene-Miocene stratigraphy and oceanic events.

    Science.gov (United States)

    Reuter, Markus; Piller, Werner E; Brandano, Marco; Harzhauser, Mathias

    2013-12-01

    Shallow-marine sediment records have the strong potential to display sensitive environmental changes in sedimentary geometries and skeletal content. However, the time resolution of most neritic carbonate records is not high enough to be compared with climatic events as recorded in the deep-sea sediment archives. In order to resolve the paleoceanographic and paleoclimatic changes during the Oligocene-Miocene transition in the Mediterranean shallow water carbonate systems with the best possible time resolution, we re-evaluated the Decontra section on the Maiella Platform (central Apennines, Italy), which acts as a reference for the correlation of Oligocene-Miocene shallow water deposits in the Mediterranean region. The 120-m-thick late Oligocene-late Miocene carbonate succession is composed of larger foraminiferal, bryozoan and corallinacean limestones interlayered with distinct planktonic foraminiferal carbonates representing a mostly outer neritic setting. Integrated multi-proxy and facies analyses indicate that CaCO3 and total organic carbon contents as well as gamma-ray display only local to regional processes on the carbonate platform and are not suited for stratigraphic correlation on a wider scale. In contrast, new biostratigraphic data correlate the Decontra stable carbon isotope record to the global deep-sea carbon isotope record. This links relative sea level fluctuations, which are reflected by facies and magnetic susceptibility changes, to third-order eustatic cycles. The new integrated bio-, chemo-, and sequence stratigraphic framework enables a more precise timing of environmental changes within the studied time interval and identifies Decontra as an important locality for correlating not only shallow and deep water sediments of the Mediterranean region but also on a global scale.

  20. Cool-water Eocene-Oligocene carbonate sedimentation on a paleobathymetric high, Kangaroo Island, southern Australia

    Science.gov (United States)

    James, Noel P.; Matenaar, Joanne; Bone, Yvonne

    2016-07-01

    The Kingscote Limestone is a thin, biofragmental ~ 41 m thick Paleogene subtropical to cool-temperate carbonate interpreted to have accumulated in a seaway developed between a series of mid-shelf islands. It is a pivotal section that allows interpretation of a region in which there is little exposure of early Cenozoic shelf sediments. Sedimentation occurred on part of the shelf along the northern margin of an extensive Eocene embayment that evolved into a narrow Oligocene ocean following collapse of the Tasman Gateway. Eocene strata are subtropical echinoid-rich floatstones with conspicuous bryozoans, and mollusks, together with large and small benthic foraminifers. Numerous echinoid rudstone storm deposits punctuate the succession. Correlation with coeval Eocene strata across southern Australia supports a regional facies model wherein inner neritic biosiliceous spiculitic sediments passed outboard into calcareous facies. The silica was derived from land covered by a thriving subtropical forest and attendant deep weathering. Oligocene rocks are distinctively cooler cyclic cross-bedded bryozoan rudstones and floatstones with a similar benthic biota but dominated by bryozoans and containing no large benthic foraminifers. These deposits are interpreted as flood-dominated tidal subaqueous dunes that formed in a flood-tide dominated inter-island strait. Omission surfaces at the top of the Eocene and at the top of most Oligocene cycles are Fe-stained hardgrounds that underwent extensive multigeneration seafloor and meteoric diagenesis prior to deposition of the next cycle. Cycles in the Kingscote Limestone, although mostly m-scale and compositionally distinct are similar to those across the region and point to a recurring cycle motif controlled by icehouse eustasy and local paleogeography.

  1. A late-surviving apatemyid (Mammalia: Apatotheria from the latest Oligocene of Florida, USA

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    Nicholas J. Czaplewski

    2015-12-01

    Full Text Available A new species of Apatemyidae, Sinclairella simplicidens, is based on four isolated teeth that were screenwashed from fissure fillings at the late Oligocene Buda locality, Alachua County, Florida. Compared to its only congener Sinclairella dakotensis, the new species is characterized by upper molars with more simplified crowns, with the near absence of labial shelves and stylar cusps except for a strong parastyle on M1, loss of paracrista and paraconule on M2 (paraconule retained but weak on M1, lack of anterior cingulum on M1–M3, straighter centrocristae, smaller hypocone on M1 and M2, larger hypocone on M3, distal edge of M2 continuous from hypocone to postmetacrista supporting a large posterior basin, and with different tooth proportions in which M2 is the smallest rather than the largest molar in the toothrow. The relatively rare and poorly-known family Apatemyidae has a long temporal range in North America from the late Paleocene (early Tiffanian to early Oligocene (early Arikareean. The new species from Florida significantly extends this temporal range by roughly 5 Ma to the end of the Paleogene near the Oligocene-Miocene boundary (from early Arikareean, Ar1, to late Arikareean, Ar3, and greatly extends the geographic range of the family into eastern North America some 10° of latitude farther south and 20° of longitude farther east (about 2,200 km farther southeast than previously known. This late occurrence probably represents a retreat of this subtropically adapted family into the Gulf Coastal Plain subtropical province at the end of the Paleogene and perhaps the end of the apatemyid lineage in North America.

  2. Meteoric diagenesis, marine diagenesis, and microporosity in Pleistocene and Oligocene limestones, Enewetak Atoll, Marshall Islands

    Science.gov (United States)

    Saller, Arthur H.; Moore, Clyde H.

    1989-07-01

    Microporosity occurs in Pleistocene and Oligocene limestones cored on Enewetak Atoll. In cores of Pleistocene limestone (10-80 m deep), mi microporosity is present in aragonitic skeletal grains that underwent partial intrafabric dissolution (chalkification) leaving a porous meshwork of aragonite needles. Microporous aragonite is most abundant in 5-10 m thick intervals below zones of intense diagenesis associated with paleo-freshwater lenses. Extensive microporosity was apparently generated by slow intrafabric dissolution of aragonite in mixing zones below freshwater lenses. Microporous aragonite is an intermediate step in the calcitization or dissolution of aragonite. Most calcitized aragonite (neomorphic calcite) formed by precipitation of sparry calcite in (over) microporous aragonite. Aragonitic fossils were not converted to microporous, microcrystalline calcite. Therefore, data from the Pleistocene of Enewetak suggest that widespread, microporous, microcrystalline calcite does not form directly from pure aragonite, at least not in open meteoric systems or mixing zones. Microporous micrite occurs in Oligocene wackestones 930 m deep deposited in a slope environment. The microporous micrite is characterized by equant and prismatic crystals of low-magnesium calcite (LMC). Equant crystals are anhedral to euhedral and 2-10 μm in diameter. Prismatic calcite crystals are subhedral, 5-10 μm wide, and 20-50 μm long. Stable isotopic and trace element geochemistry suggest that microporous micrite formed by diagenetic alteration of high-magnesium calcite (HMC) micrite in deep seawater undersaturated with respect to HMC but supersaturated with respect to LMC (probably near the sediment-water interface). Mineralogy and crystal morphology of the microporous aragonite is very different from microporous shelf limestones in the Thamama Group (Cretaceous, Persian Gulf; see Moshier, 1989). Equant microcrystals of calcite in the Oligocene micrites are similar to those in

  3. No Red River capture since the late Oligocene: Geochemical evidence from the Northwestern South China Sea

    Science.gov (United States)

    Zhao, Meng; Shao, Lei; Liang, Jianshe; Li, Qianyu

    2015-12-01

    Rare earth elements (REE) in the sediment samples of six industrial wells from the Yinggehai-Song Hong Basin in the Northwestern South China Sea were analyzed and compared with the detrital zircon U-Pb data from earlier studies to extrapolate sediment provenance. The results reveal that the Red River (Song Hong River), Hainan Island and Central Vietnam have been the main provenances of the Yinggehai-Song Hong Basin since the late Oligocene. The Red River has been supplying sediments with positive Eu anomalies from basic-ultrabasic metamorphic and volcanic parent rocks to most parts of the basin, while Hainan Island has delivered sediments with negative Eu anomalies from granitic and sedimentary parent rocks to the eastern slope area of the basin. The progradational downlap structures in the seismic profiles also support the finding that the sediment supply is mainly from the Red River and from Hainan Island. The metamorphic rocks, which are widespread within the Red River drainage, not only provided high volumes of sediments to the basin but also contributed to the positive Eu anomalies observed. Because their REE and U-Pb signatures are similar to those of the Red River source, the metamorphic and igneous rocks of the Song Ma Suture Zone, Kontum Massif, and Jinghong area were probably parts of a large basic provenance region before being separated by strike-slip movements along the Ailao Shan-Red River shear zone. Furthermore, our results indicate that the Red River drainage area has been relatively stable since the late Oligocene. Therefore, if a drainage capture from the Red River occurred, it is likely to have taken place before the late Oligocene.

  4. Phytogeographical implication of Bridelia Will. (Phyllanthaceae fossil leaf from the late Oligocene of India.

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    Gaurav Srivastava

    Full Text Available BACKGROUND: The family Phyllanthaceae has a predominantly pantropical distribution. Of its several genera, Bridelia Willd. is of a special interest because it has disjunct equally distributed species in Africa and tropical Asia i.e. 18-20 species in Africa-Madagascar (all endemic and 18 species in tropical Asia (some shared with Australia. On the basis of molecular phylogenetic study on Bridelia, it has been suggested that the genus evolved in Southeast Asia around 33±5 Ma, while speciation and migration to other parts of the world occurred at 10±2 Ma. Fossil records of Bridelia are equally important to support the molecular phylogenetic studies and plate tectonic models. RESULTS: We describe a new fossil leaf of Bridelia from the late Oligocene (Chattian, 28.4-23 Ma sediments of Assam, India. The detailed venation pattern of the fossil suggests its affinities with the extant B. ovata, B. retusa and B. stipularis. Based on the present fossil evidence and the known fossil records of Bridelia from the Tertiary sediments of Nepal and India, we infer that the genus evolved in India during the late Oligocene (Chattian, 28.4-23 Ma and speciation occurred during the Miocene. The stem lineage of the genus migrated to Africa via "Iranian route" and again speciosed in Africa-Madagascar during the late Neogene resulting in the emergence of African endemic clades. Similarly, the genus also migrated to Southeast Asia via Myanmar after the complete suturing of Indian and Eurasian plates. The emergence and speciation of the genus in Asia and Africa is the result of climate change during the Cenozoic. CONCLUSIONS: On the basis of present and known fossil records of Bridelia, we have concluded that the genus evolved during the late Oligocene in northeast India. During the Neogene, the genus diversified and migrated to Southeast Asia via Myanmar and Africa via "Iranian Route".

  5. Coralgal facies of the Upper Eocene-Lower Oligocene limestones in Letca-Rastoci area

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    Ioana Prica

    2001-09-01

    Full Text Available In this paper are described the coralgal facies identified in the Upper Eocene-Lower Oligocene limestone succession (Cozla Formation outcropping in two quarries at Letca and Rastoci (Sălaj district, Romania. In the studied profiles the coral and algae limestones are interlayered with bioclastic limestones with foraminifera. On the top of relatively deep water deposits, coral and algae crusts and dendritic corals coated by algae were deposited. The environment registered a gradual deepening, the deposits being completely immersed, while bioclastic limestones with foraminifera were recurrently formed. This cycle is repeated, the whole succession being caracterized by several such “parasequences”.

  6. Fruits of Tetrapterys (Malpighiaceae) from the Oligocene of Hungary and Slovenia.

    Science.gov (United States)

    Hably; Manchester

    2000-08-01

    Propeller-like winged fruits of Tetrapterys harpyiarum Unger from the Oligocene of Sotzka, Budapest, Eger-Vécsey valley, and a new occurrence at Eger-Kiseged, were reinvestigated and compared in detail with extant species of Tetrapterys (Malpighiaceae) and with other dicotyledonous genera with four winged fruits. T. harpyiarum fruits are bilaterally symmetrical, consisting of a globose nut surrounded by four elongate wings with parallel venation. Tetrapterys is now distributed only in tropical America and this implies that there was an opportunity for Tetrapterys to spread between the Partethys region and the New World during the Tertiary.

  7. Fossil plants indicate that the most significant decrease in atmospheric CO2 happened prior to the Eocene-Oligocene boundary

    Science.gov (United States)

    Steinthorsdottir, Margret; Porter, Amanda; Holohan, Aidan; Kunzmann, Lutz; Collinson, Margaret; McElwain, Jennifer

    2016-04-01

    A unique stratigraphic sequence of fossil leaves of Eotrigonobalanus furcinervis (extinct trees of the beech family, Fagaceae) from central Germany was utilized to derive an atmospheric pCO2 record with multiple data points spanning the late middle to late Eocene, two sampling levels which may be earliest Oligocene, and two samples from later in the Oligocene. Using the stomatal proxy, which relies on the inverse relationship between pCO2 and leaf stomatal density, we show that a ~40% decrease in pCO2 preceded the large shift in marine oxygen isotope records that characterizes the Eocene-Oliogocene climate transition. The results endorse the theory that pCO2 drawdown was the main forcer of the Eocene-Oligocene climate change, and a 'tipping point' was reached in the latest Eocene, triggering the plunge of the Earth System into icehouse conditions.

  8. Discovery of a Giant Lya Emitter Near the Reionization Epoch

    Energy Technology Data Exchange (ETDEWEB)

    Ouchi, Masami; Ono, Yoshiaki; Egami, Eiichi; Saito, Tomoki; Oguri, Masamune; McCarthy, Patrick J.; Farrah, Duncan; Kashikawa, Nobunari; Momcheva, Ivelina; Shimasaku, Kazuhiro; Nakanishi, Kouichiro; Furusawa, Hisanori; Akiyama, Masayuki; Dunlop, James S.; Mortier, Angela M.J.; Okamura, Sadanori; Hayashi, Masao; Cirasuolo, Michele; Dressler, Alan; Iye, Masanori; Jarvis, Matt.J.

    2008-08-01

    We report the discovery of a giant Ly{alpha} emitter (LAE) with a Spitzer/IRAC counterpart near the reionization epoch at z = 6.595. The giant LAE is found from the extensive 1 deg{sup 2} Subaru narrow-band survey for z = 6.6 LAEs in the Subaru/XMM-Newton Deep Survey (SXDS) field, and subsequently identified by deep spectroscopy of Keck/DEIMOS and Magellan/IMACS. Among our 207 LAE candidates, this LAE is not only the brightest narrow-band object with L(Ly{alpha}) = 3.9 {+-} 0.2 x 10{sup 43} erg s{sup -1} in our survey volume of 10{sup 6} Mpc{sup 3}, but also a spatially extended Ly{alpha} nebula with the largest isophotal area whose major axis is at least {approx_equal} 3-inches. This object is more likely to be a large Ly{alpha} nebula with a size of {approx}> 17-kpc than to be a strongly-lensed galaxy by a foreground object. Our Keck spectrum with medium-high spectral and spatial resolutions suggests that the velocity width is v{sub FWHM} = 251 {+-} 21 km s{sup -1}, and that the line-center velocity changes by {approx_equal} 60 km s{sup -1} in a 10-kpc range. The stellar mass and star-formation rate are estimated to be 0.9-5.0 x 10{sup 10}M{sub {circle_dot}} and > 34 M{sub {circle_dot}}yr{sup -1}, respectively, from the combination of deep optical to infrared images of Subaru, UKIDSS-Ultra Deep Survey, and Spitzer/IRAC. Although the nature of this object is not yet clearly understood, this could be an important object for studying cooling clouds accreting onto a massive halo, or forming-massive galaxies with significant outflows contributing to cosmic reionization and metal enrichment of inter-galactic medium.

  9. Organic Chemostratigraphic Markers Characteristic of the (Informally Designated) Anthropocene Epoch

    Science.gov (United States)

    Kruge, M. A.

    2008-12-01

    Recognizing the tremendous collective impact of humans on the environment in the industrial age, the proposed designation of the current time period as the Anthropocene Epoch has considerable merit. One of the signature activities during this time continues to be the intensive extraction, processing, and combustion of fossil fuels. While fossil fuels themselves are naturally-occurring, they are most often millions of years old and associated with deeply buried strata. They may be found at the surface, for example, as natural oil seeps or coal seam outcrops, but these are relatively rare occurrences. Fossil fuels and their myriad by- products become the source of distinctive organic chemostratigraphic marker compounds for the Anthropocene when they occur out of their original geological context, i.e., as widespread contaminants in sediments and soils. These persistent compounds have high long-term preservation potential, particularly when deposited under low oxygen conditions. Fossil fuels can occur as environmental contaminants in raw form (e.g., crude petroleum spilled during transport) or as manufactured products (e.g., diesel oil from a leaking storage facility, coal tar from a manufactured gas plant, plastic waste in a landfill, pesticides from petroleum feedstock in agricultural soils). Distinctive assemblages of hydrocarbon marker compounds including acyclic isoprenoids, hopanes, and steranes can be readily detected by gas chromatography/mass spectrometric analysis of surface sediments and soils. Polycyclic aromatic hydrocarbons (PAHs), along with sulfur-, oxygen-, and nitrogen-containing aromatic compounds, are also characteristic of fossil fuels and are readily detectable as well. More widespread is the airfall deposition of fossil fuel combustion products from vehicular, domestic and industrial sources. These occur in higher concentrations in large urban centers, but are also detected in remote areas. Parent (nonmethylated) PAHs such as phenanthrene

  10. Global vegetation distribution and terrestrial climate evolution at the Eocene-Oligocene transition

    Science.gov (United States)

    Pound, Matthew; Salzmann, Ulrich

    2016-04-01

    The Eocene - Oligocene transition (EOT; ca. 34-33.5 Ma) is widely considered to be the biggest step in Cenozoic climate evolution. Geochemical marine records show both surface and bottom water cooling, associated with the expansion of Antarctic glaciers and a reduction in the atmospheric CO2 concentration. However, the global response of the terrestrial biosphere to the EOT is less well understood and not uniform when comparing different regions. We present new global vegetation and terrestrial climate reconstructions of the Priabonian (late Eocene; 38-33.9 Ma) and Rupelian (early Oligocene; 33.9-28.45 Ma) by synthesising 215 pollen and spore localities. Using presence/absence data of pollen and spores with multivariate statistics has allowed the reconstruction of palaeo-biomes without relying on modern analogues. The reconstructed palaeo-biomes do not show the equator-ward shift at the EOT, which would be expected from a global cooling. Reconstructions of mean annual temperature, cold month mean temperature and warm month mean temperature do not show a global cooling of terrestrial climate across the EOT. Our new reconstructions differ from previous global syntheses by being based on an internally consistent statistically defined classification of palaeo-biomes and our terrestrial based climate reconstructions are in stark contrast to some marine based climate estimates. Our results raise new questions on the nature and extent of terrestrial global climate change at the EOT.

  11. Antarctic glaciation caused ocean circulation changes at the Eocene-Oligocene transition.

    Science.gov (United States)

    Goldner, A; Herold, N; Huber, M

    2014-07-31

    Two main hypotheses compete to explain global cooling and the abrupt growth of the Antarctic ice sheet across the Eocene-Oligocene transition about 34 million years ago: thermal isolation of Antarctica due to southern ocean gateway opening, and declining atmospheric CO2 (refs 5, 6). Increases in ocean thermal stratification and circulation in proxies across the Eocene-Oligocene transition have been interpreted as a unique signature of gateway opening, but at present both mechanisms remain possible. Here, using a coupled ocean-atmosphere model, we show that the rise of Antarctic glaciation, rather than altered palaeogeography, is best able to explain the observed oceanographic changes. We find that growth of the Antarctic ice sheet caused enhanced northward transport of Antarctic intermediate water and invigorated the formation of Antarctic bottom water, fundamentally reorganizing ocean circulation. Conversely, gateway openings had much less impact on ocean thermal stratification and circulation. Our results support available evidence that CO2 drawdown--not gateway opening--caused Antarctic ice sheet growth, and further show that these feedbacks in turn altered ocean circulation. The precise timing and rate of glaciation, and thus its impacts on ocean circulation, reflect the balance between potentially positive feedbacks (increases in sea ice extent and enhanced primary productivity) and negative feedbacks (stronger southward heat transport and localized high-latitude warming). The Antarctic ice sheet had a complex, dynamic role in ocean circulation and heat fluxes during its initiation, and these processes are likely to operate in the future.

  12. Provenance and palaeogeographic implications of Eocene-Oligocene sedimentary rocks in the northwestern Basin and Range

    Science.gov (United States)

    Egger, A.E.; Colgan, J.P.; York, C.

    2009-01-01

    A thick sequence of uppermost Eocene to lower Oligocene volcaniclastic and sedimentary rocks is exposed at the base of the Warner Range in northeastern California. This isolated exposure provides insight into the palaeogeographic setting of the northwestern Basin and Range during this time period. Significant thinning of the unit over 35km of lateral exposure and predominantly volcanic clast compositions suggest that the sequence was deposited in an alluvial plain adjacent to a volcanic arc. Palaeocurrent indicators in the conglomerates define a NNE transport direction. Detrital zircon analysis on coarse sandstones and dating of individual granite cobbles show a range of ages consistent with a local, volcanic source area primarily from the SSW with some far-travelled input from northern Nevada; the far-travelled component increases in influence as the unit thins to the north. Comparison with other sedimentary sequences of Eocene age and integration with palaeofloral and geophysical data help to define drainage divides, and suggest that this sequence accumulated in a relatively isolated, intra-arc basin. This localized accumulation differs markedly from contemporaneous drainages to the south that transported material westwards from central Nevada to the palaeoshoreline, and suggests that ongoing volcanism had a strong influence on palaeogeography in this region during the Eocene and Oligocene.

  13. An early Oligocene fossil demonstrates treeshrews are slowly evolving "living fossils".

    Science.gov (United States)

    Li, Qiang; Ni, Xijun

    2016-01-14

    Treeshrews are widely considered a "living model" of an ancestral primate, and have long been called "living fossils". Actual fossils of treeshrews, however, are extremely rare. We report a new fossil species of Ptilocercus treeshrew recovered from the early Oligocene (~34 Ma) of China that represents the oldest definitive fossil record of the crown group of treeshrews and nearly doubles the temporal length of their fossil record. The fossil species is strikingly similar to the living Ptilocercus lowii, a species generally recognized as the most plesiomorphic extant treeshrew. It demonstrates that Ptilocercus treeshrews have undergone little evolutionary change in their morphology since the early Oligocene. Morphological comparisons and phylogenetic analysis support the long-standing idea that Ptilocercus treeshrews are morphologically conservative and have probably retained many characters present in the common stock that gave rise to archontans, which include primates, flying lemurs, plesiadapiforms and treeshrews. This discovery provides an exceptional example of slow morphological evolution in a mammalian group over a period of 34 million years. The persistent and stable tropical environment in Southeast Asia through the Cenozoic likely played a critical role in the survival of such a morphologically conservative lineage.

  14. A tiny short-legged bird from the early Oligocene of Poland

    Directory of Open Access Journals (Sweden)

    Bochenski Zbigniew M.

    2016-10-01

    Full Text Available We describe an articulated partial leg of an Oligocene bird. It is one of the smallest avian fossils ever recorded. Its slender and exceptionally short tarsometatarsus, hallux as long as the tarsometatarsus and stout moderately curved claws agree with stem-group Apodidae (swifts, stem-group Trochilidae (hummingbirds, and stem-group Upupidae/Phoeniculidae (hoopoes/woodhoopoes. Unfortunately, due to the poor preservation of the specimen its more precise affinities remain unresolved. The specimen differs in many details from all other tiny Palaeogene birds and therefore most probably it represents a new taxon but it is too fragmentary to describe it. It is just the twelfth avian fossil from the Oligocene marine deposits of the Outer Carpathians and Central Palaeogene Basin — a huge area that covers south-eastern Poland, north-eastern Czech Republic and northern Slovakia — and therefore it adds to our very limited knowledge on the avifauna of that region. The remains of land birds from Jamna Dolna and other sites of the region can be attributed to the general sea level fall at that time, which led to limitation of the connection with the open ocean and resulted in many shallow shoals, temporary islands and exposed dry land areas along the coast.

  15. New high-precision 40Ar/39Ar ages on Oligocene volcanic rocks of northwestern Kenya

    Science.gov (United States)

    Brown, Francis H.; Jicha, Brian R.

    2016-02-01

    New, high-precision 40Ar/39Ar ages from volcanic rocks in northwestern Kenya are provided for some areas of exposure in this remote area. We report seven 40Ar/39Ar ages generated from single crystal total fusion experiments on alkali feldspar separated from volcanic rocks in the Mogila, Songot, and Lokwanamur Ranges and the Gatome valley. A rhyolite from the lower part of the sequence in the Mogila Range yielded ages of 32.31 ± 0.06 Ma and 32.33 ± 0.07 Ma, and a rhyolite near the top of that sequence yielded 31.67 ± 0.04 Ma. A single sample from the Songot Range yielded an age of 32.49 ± 0.07 Ma, slightly older than the rocks collected from Mogila. In both ranges the early Oligocene rhyolites are underlain by basalts, as is also the case in the Labur Range. Ages of 25.95 ± 0.03 Ma, 25.91 ± 0.04 Ma, and 27.15 ± 0.03 Ma were measured on alkali feldspar from rhyolites from the Lokwanamur Range, and the nearby Gatome valley. All of these rocks are part of an episode of widespread volcanism in northwestern Kenya in the mid-to late Oligocene that is not currently known from the Ethiopian Rift Valley.

  16. A tiny short-legged bird from the early Oligocene of Poland

    Science.gov (United States)

    Bochenski, Zbigniew M.; Tomek, Teresa; Swidnicka, Ewa

    2016-10-01

    We describe an articulated partial leg of an Oligocene bird. It is one of the smallest avian fossils ever recorded. Its slender and exceptionally short tarsometatarsus, hallux as long as the tarsometatarsus and stout moderately curved claws agree with stem-group Apodidae (swifts), stem-group Trochilidae (hummingbirds), and stem-group Upupidae/Phoeniculidae (hoopoes/woodhoopoes). Unfortunately, due to the poor preservation of the specimen its more precise affinities remain unresolved. The specimen differs in many details from all other tiny Palaeogene birds and therefore most probably it represents a new taxon but it is too fragmentary to describe it. It is just the twelfth avian fossil from the Oligocene marine deposits of the Outer Carpathians and Central Palaeogene Basin — a huge area that covers south-eastern Poland, north-eastern Czech Republic and northern Slovakia — and therefore it adds to our very limited knowledge on the avifauna of that region. The remains of land birds from Jamna Dolna and other sites of the region can be attributed to the general sea level fall at that time, which led to limitation of the connection with the open ocean and resulted in many shallow shoals, temporary islands and exposed dry land areas along the coast.

  17. The geochemical similarity of Oligocene and recent phosphorites from the Chiatura deposit (Georgia) and the Namibian shelf

    Science.gov (United States)

    Baturin, G. N.; Zhegallo, E. A.; Shkolnik, E. L.

    2014-12-01

    Detailed studies of the distribution of macro- and microelements in phosphorites associated with Oligocene manganese ores of the Chiatura deposit revealed their geochemical similarity to the Late Quaternary phosphorites on the recent shelf of Namibia in the Atlantic Ocean. This shows that the Chiatura nodular phosphorites were formed in the shallow-water bioproductive zone of the Oligocene basin by biogenic supply of phosphorus onto the bottom and its subsequent diagenetic concentrating similarly to the granular-nodular phosphorites on the shelf of the recent ocean. The Chiatura phosphorites were later subjected to the epigenetic impact of hydrogeological processes, which modified the initial composition of the contained rareearth elements.

  18. Stratigraphic responses to a major tectonic event in a foreland basin: the Ecuadorian Oriente Basin from Eocene to Oligocene times

    Science.gov (United States)

    Christophoul, Frédéric; Baby, Patrice; Dávila, Celso

    2002-02-01

    The Eocene to Oligocene sediments of the Ecuadorian Oriente Basin record two kinds of second-order stratigraphic response to the tectonic evolution. Lower Eocene shows evidences of local scale syntectonic deposits. This tectonic activity can be related to right lateral convergent movements inverting pre-cretaceous extensional structures. Upper Eocene and Oligocene sediments are integrated as the expression of an isostatic rebound characterizing a basin scale syntectonic deposition. This response is evidenced by a reciprocal architecture of the depositional sequences identified in the sedimentary formations. These data have allowed us to propose a new geodynamic model for the Paleogene evolution of the Oriente Basin.

  19. Further contribution to the low latitude leaf assemblage from the late Oligocene sediments of Assam and its phytogeographical significance

    Indian Academy of Sciences (India)

    Gaurav Srivastava; R C Mehrotra

    2013-10-01

    An assemblage of fossil leaves is described from the late Oligocene (Chattian 28.1–23 Ma) sediments of Assam, which was located in a low palaeolatitude (∼10–15°N) during the period of sedimentation. It includes four new fossil leaves resembling Firmiana and Pterygota of the Malvaceae s.l. and Paranephelium and Sapindus of the Sapindaceae. The present study suggests that the floral migration between India and southeast Asia had occurred after the late Oligocene. Our study is in congruence with the earlier published data suggesting a floral migration had occurred after the complete suturing of two landmasses by the Neogene.

  20. The functional central limit theorem for strong near-epoch dependent random variables

    Institute of Scientific and Technical Information of China (English)

    QIU Jin; LIN Zhengyan

    2004-01-01

    The functional central limit theorem for strong near-epoch dependent sequences of random variables is proved.The conditions given improve on previous results in the literature concerning dependence and heterogeneity.

  1. VizieR Online Data Catalog: The epoch ICRF (Xu+, 2013)

    Science.gov (United States)

    Xu, M. H.; Wang, G. L.; Zhao, M.

    2014-04-01

    The epoch International Celestial Reference Frame (epoch ICRF) is proposed as a new concept in order to consider the effect of apparent proper motion of the position of a radio source due to acceleration of the spatial origin of the ICRF, the centre of mass of the Solar system. This apparent proper motion has a magnitude of approximately 5.8-microarcsec (μas) per year, and for the 30-year very long baseline interferometry (VLBI) observational history these position variations will exceed 100μas. We show that the dipole structure of the apparent proper motions leads to global rotation in the ICRF2 and the main term, the shift of direction of the origin of right ascension, reaches 25μas per century. The 'epoch ICRF' is constructed using epoch positions at J2000.0 and apparent proper motions of radio sources, which are reported here for 295 ICRF2-defining sources. (1 data file).

  2. ATLAS BASEMAPS IN WEB 2.0 EPOCH

    Directory of Open Access Journals (Sweden)

    V. Chabaniuk

    2016-06-01

    Full Text Available The authors have analyzed their experience of the production of various Electronic Atlases (EA and Atlas Information Systems (AtIS of so-called "classical type". These EA/AtIS have been implemented in the past decade in the Web 1.0 architecture (e.g., National Atlas of Ukraine, Atlas of radioactive contamination of Ukraine, and others. One of the main distinguishing features of these atlases was their static nature - the end user could not change the content of EA/AtIS. Base maps are very important element of any EA/AtIS. In classical type EA/AtIS they were static datasets, which consisted of two parts: the topographic data of a fixed scale and data of the administrative-territorial division of Ukraine. It is important to note that the technique of topographic data production was based on the use of direct channels of topographic entity observation (such as aerial photography for the selected scale. Changes in the information technology of the past half-decade are characterized by the advent of the “Web 2.0 epoch”. Due to this, in cartography appeared such phenomena as, for example, "neo-cartography" and various mapping platforms like OpenStreetMap. These changes have forced developers of EA/AtIS to use new atlas basemaps. Our approach is described in the article. The phenomenon of neo-cartography and/or Web 2.0 cartography are analysed by authors using previously developed Conceptual framework of EA/AtIS. This framework logically explains the cartographic phenomena relations of three formations: Web 1.0, Web 1.0x1.0 and Web 2.0. Atlas basemaps of the Web 2.0 epoch are integrated information systems. We use several ways to integrate separate atlas basemaps into the information system – by building: weak integrated information system, structured system and meta-system. This integrated information system consists of several basemaps and falls under the definition of "big data". In real projects it is already used the basemaps of three strata

  3. Distances, Ages, and Epoch of Formation of Globular Clusters

    Science.gov (United States)

    Carretta, Eugenio; Gratton, Raffaele G.; Clementini, Gisella; Fusi Pecci, Flavio

    2000-04-01

    estimate for the distance of the LMC is μLMC=18.54+/-0.03+/-0.06, suggesting that distances from the subdwarf fitting method are ~1 σ too long. Consequently, our best estimate for the age of the GCs is revised to Age=12.9+/-2.9 Gyr (95% confidence range). The best relation between ZAHB absolute magnitude and metallicity is MV(ZAHB)=(0.18+/-0.09)([Fe/H]+1.5)+(0.63+/-0.07). Finally, we compare the ages of the GCs with the cosmic star formation rate recently determined by studies of the Hubble Deep Field (HDF), exploiting the determinations of ΩM=0.3 and ΩΛ=0.7 provided by Type Ia supernovae surveys. We find that the epoch of formation of the GCs (at z~3) matches well the maximum of the star formation rate for elliptical galaxies in the HDF as determined by Franceschini et al. Based on data from the Hipparcos astrometry satellite.

  4. The late Oligocene Cevizlidere Cu-Au-Mo deposit, Tunceli Province, eastern Turkey

    Science.gov (United States)

    İmer, Ali; Richards, Jeremy P.; Creaser, Robert A.; Spell, Terry L.

    2015-02-01

    The Cevizlidere deposit, located in the Tunceli Province of eastern Anatolia, is the largest porphyry Cu-Au-Mo system in Turkey. The deposit is spatially related to a composite stock, which was emplaced into Paleozoic limestones and Paleogene andesitic rocks to the southeast of the Munzur mountains, near the southwestern margin of the Ovacık pull-apart basin. The host plutonic rocks at Cevizlidere are porphyritic, medium-K calc-alkaline diorites and granodiorites. 40Ar/39Ar incremental step-heating analysis of two igneous biotite separates obtained from syn-mineral diorite porphyry yielded late Oligocene cooling ages of 25.49 ± 0.10 and 25.10 ± 0.14 Ma, whereas hydrothermal biotite yielded an age of 24.73 ± 0.08 Ma. Re-Os ages obtained from two molybdenite separates (24.90 ± 0.10 and 24.78 ± 0.10 Ma) indicate that porphyry-style alteration and mineralization developed shortly after magma emplacement. The whole-rock geochemical composition of the Cevizlidere porphyry intrusions is consistent with derivation from partial melting of the metasomatized supra-subduction zone mantle. However, based on regional tectonic reconstructions, Oligocene magmatic activity in this area appears to be related to a major kinematic reorganization that took place at around 25 Ma, during the switch from subduction to collisional tectonics in eastern Anatolia. This kinematic switch may be attributed to break-off of the Southern Neo-Tethys oceanic slab prior to the Arabia-Eurasia continent-continent collision (~12-10 Ma) following widespread middle Eocene (50-43 Ma) arc/back-arc magmatism. In this respect, the subduction-related tectonic setting of the late Oligocene Cevizlidere porphyry deposit is similar to that of the middle Eocene Çöpler epithermal Au deposit. The late timing of Cevizlidere with respect to the Southern Neo-Tethys subduction may be comparable to some early to late Miocene porphyry-epithermal systems that lie within the contiguous Urumieh-Dokhtar belt in central

  5. The Cenozoic Diversity of Agglutinated Foraminifera - Evidence for a late Oligocene to early Miocene diversification event

    Science.gov (United States)

    Kaminski, Michael; Setoyama, Eiichi; Kender, Sev; Cetean, Claudia

    2014-05-01

    The agglutinated foraminifera are among the most abundant micro-organisms in the deep marine environment and have a diversity record extending back to the late Precambrian. We present an updated diversity curve for agglutinated foraminiferal genera based on the stratigraphic ranges of all the agglutinated genera recognized as valid in the classification of Kaminski (2014). The data set for this analysis is based on the stratigraphic ranges of agglutinated genera published in Foraminiferal Genera and their Classification, which has been subsequently updated based on published studies and our new observations. The mean standing diversity of agglutinated foraminiferal genera was compiled by counting the number of boundary crossers rather than the number of genera in each stage. In this study, we report the stratigraphic and geographical occurrence of a benthic foraminiferal diversification event that has previously received little attention. In the latest Oligocene to earliest Miocene a number of trochospiral agglutinated genera with alveolar or canaliculate walls first appeared in the fossil record. Our studies of late Oligocene of the Congo fan, offshore Angola (Kender et al., 2008; Cetean and Kaminski, 2011) have revealed a diverse assemblage that includes new taxa of deep-water agglutinated foraminifera. In a biostratigraphic study of the Miocene foraminiferal assemblages Kender et al. (2008) noted steadily increasing diversity and proportions of infaunal agglutinated foraminiferal morphotypes over the lower Miocene interval. The proportion of infaunal agglutinated foraminifera assigned to the order Textularida increased dramatically in the lower mid-Miocene, suggesting expansion of the oxygen minimum zone into deeper waters. In addition to the trochospiral alveolar genera, several species of Reticulophragmium and Cyclammina display rapid diversification into numerous separate lineages that are at present not reflected in our generic diversity record owing to

  6. On the extent and significance of Oligocene mountain building in eastern Tibet (Invited)

    Science.gov (United States)

    Kirby, E.; Furlong, K. P.; Cook, K. L.; Ouimet, W. B.; Shi, X.; Wang, E.; Kamp, P. J.; Hodges, K. V.

    2013-12-01

    High topography in the region north and east of the Indo-Asian collision zone is typically considered to have developed in Miocene time, potentially in response to outward flow of weak lower crust from beneath the Tibetan Plateau. Much of the evidence for an increase in surface elevation in eastern Tibet is inferential and relies on the onset of rapid cooling and deep exhumation in the great river valleys along the plateau margin as recorded in low-temperature thermochronometers. Recently, detailed reconstruction of thermal/exhumational histories along the Longmen Shan, adjacent to the Sichuan Basin, reveals a pre-Miocene phase of mountain building (Wang et al., 2012). However, whether this event is confined to the Longmen Shan or whether it reflects widespread mountain building in the region remains unknown. Here, we synthesize emerging thermochronologic evidence from studies that utilize higher-temperature systems which are sensitive to deeper exhumation and that span various regions of the plateau margin. In the western Longmen Shan, late Oligocene - early Miocene zircon (U-Th)/He (zHe) ages from the summit of the Xuelongbao Massif (~5500m) require that mountain building was well underway along this margin by Oligocene time. In the Danba region, farther south, biotite and muscovite 40Ar/39Ar ages of samples from both fault zones and the surrounding rocks indicate that the faults were active at about 25- 30 Ma. Combined with structural and regional thermochronology data, this suggests that folding and exhumation of the Danba Anticlinorium began in mid-Tertiary time. Even farther south, along the Yalong River, biotite 40Ar/39Ar ages and zHe ages along an age-elevation transect reveal that the onset of rapid exhumation began around the same time, at ca. 30 Ma. Our results, in conjunction with existing data on the timing of deformation along the Aliao-Shan/Red River shear zone, implies that the onset of mountain building in eastern Tibet was widespread in late

  7. The micromammal fauna from the upper Oligocene of Sayatón 6, Madrid Basin, Prov. of Guadalajara, Spain

    NARCIS (Netherlands)

    Daams, R.

    1989-01-01

    The extremely poor rodent fauna of Sayatón 6 is described. Only three species are present, of which two are new: Adelomyarion alberti sp. nov. (Cricetidae) and Peridyromys columbarii sp. nov. (Gliridae). The third species, Rhodanomys transiens, places the age of the fauna in the Late Oligocene.

  8. Long Wavelenth Subsidence of Western Europe during Late Eocene-Oligocene (38-23 Ma): Mantle Dynamic Effect?

    Science.gov (United States)

    Guillocheau, Francois; Robin, Cécile; Bessin, Paul

    2015-04-01

    Western Europe (France, southern Britain, southern Belgium, western Germany) is subsiding during Late Eocene to Oligocene (38-23 Ma) as suggested by the growth of numerous small sedimentary basins mainly filled by lacustrine deposits with some brackish to marine deposits. This large-scale subsidence is coeval with the early stage of the so-called Oligocene rifts (in fact Late Bartonian to Rupelian): Lower Rhinegraben, Bresse, Limagnes. The subsiding domain extends from Cornwall to the Rhine Graben including the Armorican Massif, the southern Paris Basin, the northern Aquitaine Basin, the French Central Massif, the Ardennes-Eifel… This subsidence occurred at a period of global sea level fall and then an eustatic component cannot explain (1) the accommodation space creation and (2) the marine floding with a paroxysm during Early Oligocene times (Armorican Massif, ?Ardennes, French Massif central). This marine flooding also indicate that the relief of the Hercynian basement was less elevated and smoother than today. Some of those small "basins" were interpreted as little rifts, but new mapping (e.g. Puy-en-Velay or Forez Plain in the French Massif central) or new geophysical data (e.g. Rennes Basin in the Armorican massif) suggest that no faults control those basins or that they result from post-depositional collapses. This long wavelength subsidence is at the scale of the mantle dynamic. Possible mantle mechanisms and the relationships with the "Oligocene" rifts and the North Sea inversion will be discussed.

  9. Multiproxy record of abrupt sea-surface cooling across the Eocene-Oligocene transition in the Gulf of Mexico

    NARCIS (Netherlands)

    Wade, B.S.; Houben, A.J.P.; Quaijtaal, W.; Schouten, S.; Rosenthal, Y.; Miller, K.G.; Katz, M.E.; Wright, J.D.; Brinkhuis, H.

    2012-01-01

    The Eocene-Oligocene transition (EOT; ca. 33–34 Ma) was a time of pronounced climatic change, marked by the establishment of continental-scale Antarctic ice sheets. The timing and extent of temperature change associated with the EOT is controversial. Here we present multiproxy EOT climate records (∼

  10. Orbital forcing and climate response : astronomically-tuned age models and stable isotope records for the Oligocene-Miocene

    NARCIS (Netherlands)

    Beddow-Twigg, H.M.

    2016-01-01

    The primary aim of this thesis is to reconstruct the evolution of the cryosphere, global ocean temperatures and the carbon cycle during the Oligocene-Miocene interval; using high-resolution foraminiferal stable isotope records with accurate chronological control provided by astronomically tuned age

  11. Multiproxy record of abrupt sea-surface cooling across the Eocene-Oligocene transition in the Gulf of Mexico

    NARCIS (Netherlands)

    Wade, B.S.; Houben, A.J.P.; Quaijtaal, W.; Schouten, S.; Rosenthal, Y.; Miller, K.G.; Katz, M.E.; Wright, J.D.; Brinkhuis, H.

    2012-01-01

    The Eocene-Oligocene transition (EOT; ca. 33–34 Ma) was a time of pronounced climatic change, marked by the establishment of continental-scale Antarctic ice sheets. The timing and extent of temperature change associated with the EOT is controversial. Here we present multiproxy EOT climate records (~

  12. The micromammal fauna from the upper Oligocene of Sayatón 6, Madrid Basin, Prov. of Guadalajara, Spain

    NARCIS (Netherlands)

    Daams, R.

    1989-01-01

    The extremely poor rodent fauna of Sayatón 6 is described. Only three species are present, of which two are new: Adelomyarion alberti sp. nov. (Cricetidae) and Peridyromys columbarii sp. nov. (Gliridae). The third species, Rhodanomys transiens, places the age of the fauna in the Late Oligocene.

  13. Faint Object Detection in Multi-Epoch Observations via Catalog Data Fusion

    Science.gov (United States)

    Budavári, Tamás; Szalay, Alexander S.; Loredo, Thomas J.

    2017-03-01

    Astronomy in the time-domain era faces several new challenges. One of them is the efficient use of observations obtained at multiple epochs. The work presented here addresses faint object detection and describes an incremental strategy for separating real objects from artifacts in ongoing surveys. The idea is to produce low-threshold single-epoch catalogs and to accumulate information across epochs. This is in contrast to more conventional strategies based on co-added or stacked images. We adopt a Bayesian approach, addressing object detection by calculating the marginal likelihoods for hypotheses asserting that there is no object or one object in a small image patch containing at most one cataloged source at each epoch. The object-present hypothesis interprets the sources in a patch at different epochs as arising from a genuine object; the no-object hypothesis interprets candidate sources as spurious, arising from noise peaks. We study the detection probability for constant-flux objects in a Gaussian noise setting, comparing results based on single and stacked exposures to results based on a series of single-epoch catalog summaries. Our procedure amounts to generalized cross-matching: it is the product of a factor accounting for the matching of the estimated fluxes of the candidate sources and a factor accounting for the matching of their estimated directions. We find that probabilistic fusion of multi-epoch catalogs can detect sources with similar sensitivity and selectivity compared to stacking. The probabilistic cross-matching framework underlying our approach plays an important role in maintaining detection sensitivity and points toward generalizations that could accommodate variability and complex object structure.

  14. Fossil traces of the bone-eating worm Osedax in early Oligocene whale bones.

    Science.gov (United States)

    Kiel, Steffen; Goedert, James L; Kahl, Wolf-Achim; Rouse, Greg W

    2010-05-11

    Osedax is a recently discovered group of siboglinid annelids that consume bones on the seafloor and whose evolutionary origins have been linked with Cretaceous marine reptiles or to the post-Cretaceous rise of whales. Here we present whale bones from early Oligocene bathyal sediments exposed in Washington State, which show traces similar to those made by Osedax today. The geologic age of these trace fossils ( approximately 30 million years) coincides with the first major radiation of whales, consistent with the hypothesis of an evolutionary link between Osedax and its main food source, although older fossils should certainly be studied. Osedax has been destroying bones for most of the evolutionary history of whales and the possible significance of this "Osedax effect" in relation to the quality and quantity of their fossils is only now recognized.

  15. Late Eocene-Oligocene Te Kuiti Group at Mount Roskill, Auckland, New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Edbrooke, S.W.; Crouch, E.M.; Morgans, H.E.G.; Sykes, R. [Institute of Geology and Nuclear Sciences, Lower Hutt (New Zealand)

    1998-03-01

    A 592 m deep water bore drilled at Mount Roskill in central Auckland, New Zealand, produced the first record of the Te Kuiti Group in Central Auckland. The group comprised erosionally truncated Glen Massey Formation beneath the Waitemata Group, a complete section through Mangakotuku Formation, and an incomplete Waikato Coal Measures section. Drilling stopped in Waikato Coal Measures, probably less than 30 m short of Paleozoic or Mesozoic basement. Vitrinite reflectance measurements indicate a lignite rank for coal fragments collected from the coal measures, and suggest a maximum burial depth of c. 800 m. Six Te Kuiti Group samples examined for palynomorphs and foraminifers gave ages ranging from Runangan to early Whaingaroan and show a transition from a predominantly terrestrial late Eocene environment to a shallow marine setting in the early Oligocene. Results support the suggestion that the southern limit to the Northland Allochthon lies north of Auckland.

  16. Decreased Temperate but not Polar Fish Productivity Across the Eocene-Oligocene Transition: Insights from Ichthyoliths

    Science.gov (United States)

    Zill, M.; Sibert, E. C.; Norris, R. D.

    2015-12-01

    The Eocene-Oligocene Transition (EOT, 38-28 Ma) was a period of global cooling and increased nutrient delivery to the ocean. It is associated with the onset of permanent ice sheet on Antarctica, and the beginning of a highly productive polar ecosystem, dominated by diatoms and favoring short, efficient food chains. In a highly efficient, large phytoplankton-dominated ecosystem, we would expect to see higher abundances of consumers, as fewer trophic steps means more carbon available to upper trophic level groups. Here we use the accumulation rate of ichthyoliths (fish teeth and dermal scales) to measure the relative export production of fish through this time period of changing climate. Records from the South Atlantic gyre (DSDP Site 522) the South Pacific Gyre (DSDP Site 596) and the Southern Ocean (DSDP Site 689) show a 50% reduction in ichthyolith accumulation rate in the vicinity the Eocene Oligocene boundary. However, this drop in fish production occurs just after the E/O in the Atlantic, 4 million years before the E/O in the Pacific and 6 million years prior to the E/O in the Southern Ocean. Since the EOT is generally associated with an increase in productivity and diatom blooms in the Southern Ocean and tropical Pacific, we would expect that the abundance of fish would increase across the transition. Our results are surprisingly the inverse of this expectation, and suggest that the transition from greenhouse to icehouse did not produce increase in forage fish or even a response of any kind during the climatological transition into the icehouse world. Indeed, it seems that ichthyolith accumulation rate and primary productivity are not perfectly linked, and it may be that ichthyolith accumulation is responding more to another factor, such as ocean temperature or prey availability that is not linked to the increased diatom production during the EOT.

  17. Synchronizing terrestrial and marine records of environmental change across the Eocene-Oligocene transition

    Science.gov (United States)

    Sahy, Diana; Condon, Daniel J.; Terry, Dennis O.; Fischer, Anne U.; Kuiper, Klaudia F.

    2015-10-01

    Records of terrestrial environmental change indicate that continental cooling and/or aridification may have predated the greenhouse-icehouse climate shift at the Eocene-Oligocene transition (EOT) by ca. 600 kyr. In North America, marine-terrestrial environmental change asynchronicity is inferred from a direct comparison between the astronomically tuned marine EOT record and published 40Ar/39Ar geochronology of volcanic tuffs from the White River Group (WRG) sampled at Flagstaff Rim (Wyoming) and Toadstool Geologic Park (Nebraska), which are type sections for the Chadronian and Orellan North American Land Mammal Ages. We present a new age-model for the WRG, underpinned by high-precision 206Pb/238U zircon dates from 15 volcanic tuffs, including six tuffs previously dated using the 40Ar/39Ar technique. Weighted mean zircon 206Pb/238U dates from this study are up to 1.0 Myr younger than published anorthoclase and biotite 40Ar/39Ar data (calibrated relative to Fish Canyon sanidine at 28.201 Ma). Giving consideration to the complexities, strengths, and limitations associated with both the 40Ar/39Ar and 206Pb/238U datasets, our interpretation is that the recalculated 40Ar/39Ar dates are anomalously old, and the 206Pb/238U (zircon) dates more accurately constrain deposition. 206Pb/238U calibrated age-depth models were developed in order to facilitate a robust intercomparison between marine and terrestrial archives of environmental change, and indicate that: (i) early Orellan (terrestrial) cooling recorded at Toadstool Geologic Park was synchronous with the onset of early Oligocene Antarctic glaciation and (ii) the last appearance datums of key Chadronian mammal taxa are diachronous by ca. 0.7 Myr between central Wyoming and NW Nebraska.

  18. EARLY TO LATE OLIGOCENE CALCAREOUS NANNOFOSSIL BIOEVENTS IN THE MEDITERRANEAN (UMBRIA-MARCHE BASIN, CENTRAL ITALY

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    PATRIZIA MAIORANO

    2006-07-01

    Full Text Available Calcareous nannofossil assemblages have been investigated by means of quantitative analyses in three Oligocene pelagic sections located in the Umbria-Marche Apennines (Central Italy. The studied sections mainly consist of marly limestones and marls belonging to the Scaglia Cinerea Formation, and include the interval between NP23 and NP25 representing a time interval of about 3.5 Ma. Biostratigraphic resolution is extremely low and only two standard bioevents are known, which are the FO of Sphenolithus ciperoensis and the LO of Sphenolithus distentus. The distribution patterns of poorly known or recently described calcareous nannofossils provided a valuable tool for improving the current biostratigraphic framework. The studied interval is characterized by significant changes in the calcareous nannofossil assemblages and by several extinction events. The last occurrence (LO and/or the last common occurrence (LCO here proposed are: the LO of Sphenolithus akropodus, the LO of Reticulofenestra circus, the LCO of Helicosphaera ethologa, the LCO of Helicosphaera compactathe LO of Discoaster tanii nodifer. The reversal in abundance between Sphenolithus predistentus and S. distentus provided an additional biostratigraphic constraint at the NP23-NP24 transition. In addition biometric criteria enabled the recognition of the first common occurrence (FCO of Cyclicargolithus abisectus > 12 mm as potential bioevent within NP24. The quantitative distribution of Sphenolithus distentus suggests to rely on the LCO of the species rather than on the LO, for the identification of NP24-NP25 boundary. The identified bioevents is a first step towards the improvement of the present Mediterranean biostratigraphic framework of the Oligocene geological record. A preliminary correlation of the bioevents to the Geomagnetic Polarity Time Scale is presented.

  19. Arktocara yakataga, a new fossil odontocete (Mammalia, Cetacea from the Oligocene of Alaska and the antiquity of Platanistoidea

    Directory of Open Access Journals (Sweden)

    Alexandra T. Boersma

    2016-08-01

    Full Text Available The diversification of crown cetacean lineages (i.e., crown Odontoceti and crown Mysticeti occurred throughout the Oligocene, but it remains an ongoing challenge to resolve the phylogenetic pattern of their origins, especially with respect to stem lineages. One extant monotypic lineage, Platanista gangetica (the Ganges and Indus river dolphin, is the sole surviving member of the broader group Platanistoidea, with many fossil relatives that range from Oligocene to Miocene in age. Curiously, the highly threatened Platanista is restricted today to freshwater river systems of South Asia, yet nearly all fossil platanistoids are known globally from marine rocks, suggesting a marine ancestry for this group. In recent years, studies on the phylogenetic relationships in Platanistoidea have reached a general consensus about the membership of different sub-clades and putative extinct groups, although the position of some platanistoid groups (e.g., Waipatiidae has been contested. Here we describe a new genus and species of fossil platanistoid, Arktocara yakataga, gen. et sp. nov. from the Oligocene of Alaska, USA. The type and only known specimen was collected from the marine Poul Creek Formation, a unit known to include Oligocene strata, exposed in the Yakutat City and Borough of Southeast Alaska. In our phylogenetic analysis of stem and node-based Platanistoidea, Arktocara falls within the node-based sub-clade Allodelphinidae as the sister taxon to Allodelphis pratti. With a geochronologic age between ∼29–24 million years old, Arktocara is among the oldest crown Odontoceti, reinforcing the long-standing view that the diversification for crown lineages must have occurred no later than the early Oligocene.

  20. The East Africa Oligocene intertrappean beds: Regional distribution, depositional environments and Afro/Arabian mammal dispersals

    Science.gov (United States)

    Abbate, Ernesto; Bruni, Piero; Ferretti, Marco Peter; Delmer, Cyrille; Laurenzi, Marinella Ada; Hagos, Miruts; Bedri, Omar; Rook, Lorenzo; Sagri, Mario; Libsekal, Yosief

    2014-11-01

    The extensive outpouring of the Oligocene Trap basalts over eastern Africa and western Arabia was interrupted by a period of quiescence marked by the deposition of terrestrial sediments. These so-called intertrappean beds are often lignitiferous and yield recurrent floras and faunas, sometimes represented by endemic mammals. We intended to highlight the peculiar features of these sedimentary intercalations using a large-scale approach including eastern Africa and the western Arabian peninsula. Starting from a new mapping in the Eritrean highland, the intertrappean beds resulted a continuous level that was a few tens of meters thick and traceable for some tens of kilometers. They consist of fluvial red, green and gray mudstones and siltstones with subordinate channelized pebbly sandstones, and lignite seams. Two new 40Ar-39Ar datings constraint the age of the intertrappean beds between 29.0 Ma and 23.6 Ma. The outcrops near Mendefera have yielded the remains of two proboscidean families, the Deinotheriidae and the Gomphoteriidae. The morphological grade of the two Mendefera proboscideans would suggest a more derived stage than that of representatives of the same families from other Oligocene African sites (e.g., Chilga, Ethiopia). An Oligocene age could be inferred for them. The occurrence of the genus Prodeinotherium at Mai Gobro possibly represents the first occurrence of this taxon, while the Gomphotheirum sp. might represent the oldest occurrence of this taxon in Africa before its dispersal towards Asia and Europe. Proboscideans have also been found in the lowland intertrappean beds of Dogali near Massawa. These sediments were contiguous with the Eritrean highland intertrappean beds during the Oligocene, but are now tectonically displaced from them by two thousand meters of vertical topographical distance. Dogali is also known for the occurrence of possible Deinotheriidae remains and the primitive elephantoid Eritreum. Entering the Ethiopian highland, an

  1. The pulsar B2224+65 and its jets: a two epoch X-ray analysis

    Science.gov (United States)

    Johnson, S. P.; Wang, Q. D.

    2010-10-01

    We present an X-ray morphological and spectroscopic study of the pulsar B2224+65 and its apparent jet-like X-ray features based on two epoch Chandra observations. The main X-ray feature, which shows a large directional offset from the ram-pressure confined pulsar wind nebula (Guitar nebula), is broader in apparent width and shows evidence for spectral hardening (at 95 per cent confidence) in the second epoch compared to the first. Furthermore, the sharp leading edge of the feature is found to have a proper motion consistent with that of the pulsar (~180 mas yr-1). The combined data set also provides evidence for the presence of a counter feature, albeit substantially fainter and shorter than the main one. Additional spectral trends along the major and minor axes of the feature are only marginally detected in the two epoch data, including softening counter to the direction of proper motion. Possible explanations for the X-ray features include diffuse energetic particles being confined by an organized ambient magnetic field as well as a simple ballistic jet interpretation; however, the former may have difficulty in explaining observed spectral trends between epochs and along the feature's major axis, whereas the latter may struggle to elucidate its linearity. Given the low counting statistics available in the two epoch observations, it remains difficult to determine a physical production scenario for these enigmatic X-ray emitting features with any certainty.

  2. EEG epoch selection: lack of alpha rhythm improves discrimination of Alzheimer's disease.

    Science.gov (United States)

    Fraga, Francisco J; Oliveira, Eliezyer F; Kanda, Paulo A M

    2016-08-01

    In this work we propose a detailed EEG epoch selection method and compare epochs with rare and abundant alpha rhythm (AR) of patients with Alzheimer's disease (AD) and normal controls. Epochs were classified as Dominant Alpha Scenario (DAS) and Rare Alpha Scenario (RAS) according to the AR percentage (energy within the 8-13 Hz bandwidth) in O1, O2 and Oz electrodes. Participants were divided into four groups: 17 DAS controls (N1), 15 DAS mild-AD patients (AD1), 12 RAS controls (N2) and 15 RAS mild-AD patients (AD2). We found out that scenario factor (DAS vs. RAS, two-way ANOVA) is significant over a great amount of electrode-bandwidth situations. Furthermore, one-way ANOVA showed significant differences between RAS AD and RAS controls in much more situations as compared to DAS. This is the first study using AD awake EEG reporting the decisive influence of alpha rhythm on epoch selection, where our results revealed that, contrary to what was initially expected, EEG epochs with poor alpha (RAS) discriminate mild AD much better than those presenting richer alpha content (DAS).

  3. Making and breaking an Island arc: a new perspective from the Oligocene Kyushu-Palau arc

    Science.gov (United States)

    Ishizuka, O.; Taylor, R. N.; Yuasa, M.; Ohara, Y.

    2010-12-01

    The Kyushu-Palau Ridge (KPR) is a 2000km long remnant island arc that is separated from the active Izu-Bonin-Mariana (IBM) arc system by a series of spreading and rift basins. In this study we present 40Ar/39Ar ages and geochemical data for new samples taken from the entire length of the Kyushu-Palau arc. As such, this data provides the first comprehensive evaluation of temporal and spatial changes that are present in an Eocene-Oligocene island arc. Kyushu-Palau arc geochemistry is evaluated alongside new data from the conjugate arc which is stranded within the IBM fore-arc. Boninitic magmatism gave way to transitional arc suites including high-Mg andesites at c. 45 Ma (Ishizuka et al., 2006). After the transitional 45-41 Ma period, a mature arc system developed through the Eocene-Oligocene time: This volcanism is now preserved as the KPR. Dating results from 33 sites indicate that the KPR was active between 25 and 43 Ma, but the majority of the exposed volcanism occurred in the final phase of this arc, between 25 and 27 Ma. Unlike the IBM, the KPR has only limited systematic along-arc trends and does not include any of the strongly HIMU lavas found to the south of Izu-Bonin. Two components found along the KPR are found to have geochemistry that suggests an origin in the supra-subduction mantle rather than from the descending ocean crust. Firstly, in the south of the arc, EM-2-like lavas are present where the West Philippine Basin was in the final stages of spreading. Secondly, EM-1-like lavas are present in a restricted section of the arc, suggesting a localised heterogeneity. Subduction flux beneath the KPR generally imparted a Pb isotope vector towards low Δ8/4 (19). This is a similar trend to the Eocene/Oligocene lavas found on the eastern side of the basins which split the arc at 25Ma. Another geochemical heterogeneity is found at the KPR-Daito Ridge intersection where arc magmatism occurred on pre-existing Daito Ridge crust: a Cretaceous remnant arc

  4. Paleomagnetism of the Oligocene Kangtuo Formation red beds (Central Tibet): Inclination shallowing and tectonic implications

    Science.gov (United States)

    Ding, Jikai; Zhang, Shihong; Chen, Weiwei; Zhang, Junhong; Yang, Tianshui; Jiang, Gaolei; Zhang, Kexin; Li, Haiyan; Wu, Huaichun

    2015-05-01

    A paleomagnetic study on the red beds of the Oligocene Kangtuo Formation (Fm) was carried out in the Gerze Basin of the Lhasa terrane. A total of 700 samples were collected from 37 sites. Stepwise thermal demagnetization revealed that the main magnetic carrier is hematite. The natural remnant magnetization (NRM) consists of two components. A low-temperature component (LTC) is identified below 300 °C and is interpreted to be a recent viscous overprint, whereas a high temperature component (HTC) unblocks at ∼665-690 °C and is interpreted to be the primary magnetization. The HTC distributions show a clear east-west elongated distribution, which is considered as reflecting inclination flattening of deposited magnetic remanence carriers. After inclination calibration using the E/I method, the HTC could pass both a reversal test and a fold test at 95% confidence level, showing the mean direction at Ds = 340.3°, Is = 44.2°, with k = 63.0, and α95 = 3.1°, corresponding to a paleopole at 71.7°N, 339.3°E (A95 = 3.1°), and the paleolatitude of the sampling site at 25.9 ± 3.1°N. The paleolatitude is consistent with that expected from the coeval pole of the Qiangtang terrane obtained from volcanic rocks, suggesting that there has been no paleomagnetically-discernable latitudinal motion between the Qiantang and Lhasa terranes since ∼30 Ma. Comparing our new data with the apparent polar wander paths (APWPs) of East Asian blocks (Cogné et al., 2013), Europe, and India (Besse and Courtillot, 2002), we have reached the following conclusions. (1) There is no significant paleolatitudinal difference observed between the Lhasa terrane and other central and northern Asian terranes at ∼30 Ma. (2) The observed paleolatitude of the Kangtuo Fm is 8.0 ± 4.9° lower than the expected paleolatitude deduced from the data of stable Europe, highlighting the 'Asian inclination anomaly' phenomenon, but is 4.6 ± 5.1° higher than that deduced from the data of the India Plate

  5. Arabia/Africa/Eurasia kinematics and the Dynamics of Post-Oligocene Mediterranean Tectonics

    Science.gov (United States)

    McClusky, S.; Reilinger, R. E.

    2010-12-01

    Geodetic and plate tectonic observations indicate that the rate of Africa (AF) - Eurasia (EU) convergence slowed by ~50% at 24 +/- 4 Ma when AF began to separate from Arabia (AR) initiating extension along the Red Sea and Gulf of Aden. A further ~50% slowing of AF-EU convergence occurred at 11+/- 2 Ma when extension in the Gulf of Aden evolved to full ocean spreading, completely severing this segment of the AR-AF plate boundary, thereby reducing the slab-pull from Zagros-Makran subduction on the AF plate. This change in torque balance also caused an increase in the N-S component of AR-AF motion resulting in kinematic changes in both the northern (Dead Sea Fault/Sinai/Gulf of Suez) and southern (Danakil/Afar) Red Sea. While AF-EU convergence slowed, AR-EU convergence remained approximately constant from >21 Ma to the present. Contemporaneous with the initial slowing of AF-EU convergence, extension initiated along the entire AF-EU boundary (Alboran, Central Mediterranean [Tyrrenian, Balearic], and Aegean basins). The timing of the initial slowing of AF-EU convergence (~25 Ma; Late Oligocene/Early Miocene) corresponds to the initiation of extensional tectonics in the Mediterranean Basin (Alboran, Central Mediterranean [Tyrrenian, Balearic], and Aegean basins), and the second phase of slowing to changes in the character of Mediterranean extension reported at ~ 11 Ma (Tortonian). Based on theoretical considerations indicating that buoyancy forces on the subducted lithosphere are proportional to the rate of subduction, we hypothesize that the slowing of AF-EU convergence caused an imbalance in the dynamic equilibrium of the subducting Neotethys oceanic lithosphere beneath the Mediterranean segment of the plate boundary, resulting in foundering of the subducted plate, and associated southward migration of the trench system. Southward trench migration resulted in contemporaneous ~N-S extension within the Mediterranean Basin. The detailed configuration of these extensional

  6. Paleogeography and Depositional Systems of Cretaceous-Oligocene Strata: Eastern Precordillera, Argentina

    Science.gov (United States)

    Reat, Ellen J.; Fosdick, Julie C.

    2016-04-01

    New data from the Argentine Precordillera in the southern Central Andes document changes in depositional environment and sediment accumulation rates during Upper Cretaceous through Oligocene basin evolution, prior to the onset Miocene foredeep sedimentation. This work presents new sedimentology, detrital geochronology, and geologic mapping from a series of continental strata within this interval to resolve the timing of sedimentation, nature of depositional environments, and basin paleogeography at the nascent phase of Andean orogenic events, prior to the uplift and deformation of the Precordillera to the west. Five stratigraphic sections were measured across both limbs of the Huaco Anticline, detailing sedimentology of the terrestrial siliciclastic upper Patquía, Ciénaga del Río Huaco (CRH), Puesto la Flecha, Vallecito, and lower Cerro Morado formations. Paleocurrent data indicate a flow direction change from predominantly NE-SW in the upper Patquía and the lower CRH to SW-NE directed flow in the upper CRH, consistent with a large meandering river system and a potential rise in topography towards the west. This interpretation is further supported by pebble lag intervals and 1-3 meter scale trough cross-bedding in the CRH. The thinly laminated gypsum deposits and siltstones of the younger Puesto la Flecha Formation indicate an upsection transition into overbank and lacustrine sedimentation during semi-arid climatic conditions, before the onset of aeolian dune formation. New maximum depositional age results from detrital zircon U-Pb analysis indicate that the Puesto la Flecha Formation spans ~57 Myr (~92 to ~35 Ma) across a ~48 m thick interval without evidence for major erosion, indicating very low sedimentation rates. This time interval may represent distal foredeep or forebulge migration resultant from western lithospheric loading due to the onset of Andean deformation at this latitude. Detrital zircon U-Pb age spectra also indicate shifts in sediment routing

  7. NON-GENICULATE CORALLINE ALGAE (CORALLINALES, RHODOPHYTA FROM THE LOWER OLIGOCENE OF POLJŠICA PRI PODNARTU (NORTHERN SLOVENIA

    Directory of Open Access Journals (Sweden)

    LUKA GALE

    2009-03-01

    Full Text Available Despite their increasing importance in sedimentology and palaeoecology, non-geniculate coralline algae remain virtually overlooked in Slovenia. Though these plants are present or even abundant in the Cretaceous and Cainozoic strata, they have never been studied in detail with notable exception of corallines from the Lower Oligocene beds in the area of Gornji Grad. Poljšica pri Podnartu is another locality where Lower Oligocene beds are exposed, considered as equivalent to the former. The studied profile consists of pebbly limestone, mudstone, sandstone and limestone. Limestones contain abundant non-geniculate coralline algae. Nine species from six genera of these corallines have been identified: Lithoporella melobesioides (Foslie Foslie, 1909, Neogoniolithon contii (Mastrorilli Quaranta et al., 2007, Spongites sp., Lithothamnion sp. 1, Lithothamnion sp. 2, Mesophyllum sp. 1, Mesophyllum sp. 2, Mesophyllum sp. 3 and Sporolithon sp. Some of these species are described from Slovenia for the first time. 

  8. New tropical carcharhinids (chondrichthyes, carcharhiniformes) from the late Eocene early Oligocene of Balochistan, Pakistan: Paleoenvironmental and paleogeographic implications

    Science.gov (United States)

    Adnet, S.; Antoine, P.-O.; Hassan Baqri, S. R.; Crochet, J.-Y.; Marivaux, L.; Welcomme, J.-L.; Métais, G.

    2007-04-01

    New selachians (sharks and rays) have been collected from several late Eocene and early Oligocene marine localities in the Bugti Hills (Balochistan, Pakistan). Two new species of Requiem sharks (close to the Recent "Bull shark") are described : Carcharhinus balochensis and Carcharhinus perseus. The rest of the fauna is notable for the strong representation of Carcharhiniformes. These selachian faunas represent a unique tropical association for the Oligocene period and one of the first modern tropical selachian faunas, with modern taxa such as the two new species of "Bull sharks", Negaprion sp. and one of the first occurrences of Sphyrna sp. Moreover, these faunas permit paleoenvironmental interpretation of adjacent land masses. The relatively modern aspect of these faunas, compared with other contemporaneous and younger selachian associations from Atlantic and Mediterranean seas, suggests biogeographic isolation of selachian communities living in eastern and western parts of the Tethys before its final closure during the early-middle Miocene.

  9. Evidence for Tibetan Plateau Uplift in Qaidam Basin before Eocene-Oligocene Boundary and Its Climatic Implications

    Institute of Scientific and Technical Information of China (English)

    Pei Junling; Sun Zhiming; Wang Xisheng; Zhao Yue; Ge Xiaohong; Guo Xinzhuan; Li Haibing; Si Jialiang

    2009-01-01

    Geometry analysis of the Hongsanhan (红三旱) Section in the northwestern Qaidam basin illustrates the typical growth strata in the Xiaganchaigou (下干柴沟) Formation. The age and sedimentation rates of the Xiaganchaigou and the Shangganchaigou (上干柴沟) formations were determined by the high-resolution magnetostratigraphy. This result shows that the growth strata began to form at ca. 38.0 Ma and increased sedimentation rates occurred at ca. 37.0 Ma. The uplift of the Tibetan plateau before the Eocene-Oligocene boundary is confirmed, which enables us to better understand the relationship between climatic changes and the tectonic uplift. This uplift event could have resuited in the regional drying by blocking the moisture and contributed to the Eocene-Oligocene boundary global cooling event due to the declining atmospheric CO2 concentrations by increased weathering of the mountains.

  10. New remains of the baluchithere Paraceratherium bugtiense(Pilgrim, 1910) from the Late/latest Oligocene of the Bugti hills, Balochistan, Pakistan

    Science.gov (United States)

    Antoine, Pierre-Olivier; Ibrahim Shah, S. M.; Cheema, Iqbal U.; Crochet, Jean-Yves; Franceschi, Dario de; Marivaux, Laurent; Métais, Grégoire; Welcomme, Jean-Loup

    2004-10-01

    New dental and postcranial remains referred to the giant rhinocerotoid Paraceratherium bugtiense are described, originating from its type locality (Lundo Chur), in eastern Balochistan (Pakistan). Probable sexual dimorphism is revealed on the lower incisors. The manus was tridactyl, with a reduced fifth metacarpal. The stratigraphic range of both P. bugtiense and the amynodontid Cadurcotherium indicum extends from the Early Early Oligocene to the Late/latest Oligocene in the Bugti Hills.

  11. On the spin-temperature evolution during the epoch of reionization

    NARCIS (Netherlands)

    Thomas, Rajat M.; Zaroubi, Saleem

    2011-01-01

    Simulations estimating the brightness temperature (delta T-b) of the redshifted 21 cm from the epoch of reionization (EoR) often assume that the spin temperature (T-s) is decoupled from the background cosmic microwave background (CMB) temperature and is much larger than it, i.e. T-s T-CMB. Although

  12. Detectability of the 21-cm CMB cross-correlation from the epoch of reionization

    NARCIS (Netherlands)

    Tashiro, Hiroyuki; Aghanim, Nabila; Langer, Mathieu; Douspis, Marian; Zaroubi, Saleem; Jelic, Vibor

    2010-01-01

    The 21-cm line fluctuations and the cosmic microwave background (CMB) are powerful probes of the epoch of reionization of the Universe. We study the potential of the cross-correlation between 21-cm line fluctuations and CMB anisotropy to obtain further constraints on the reionization history. We ana

  13. On the spin-temperature evolution during the epoch of reionization

    NARCIS (Netherlands)

    Thomas, Rajat M.; Zaroubi, Saleem

    2011-01-01

    Simulations estimating the brightness temperature (δTb) of the redshifted 21 cm from the epoch of reionization (EoR) often assume that the spin temperature (Ts) is decoupled from the background cosmic microwave background (CMB) temperature and is much larger than it, i.e. Ts≫TCMB. Although a valid a

  14. Magnetospheric Emissions from the Planet Orbiting tau Boo: A Multi-Epoch Search

    CERN Document Server

    Lazio, T Joseph W

    2007-01-01

    All of the solar system gas giants produce electron cyclotron masers, driven by the solar wind impinging on their magnetospheres. Extrapolating to the planet orbiting tau Boo, various authors have predicted that it may be within the detection limits of the 4-meter wavelength (74 MHz) system on the Very Large Array. This paper reports three epochs of observations of tau Boo. In no epoch do we detect the planet; various means of determining the upper limit to the emission yield single-epoch limits ranging from 135 to 300 mJy. We develop a likelihood method for multi-epoch observations and use it to constrain various radiation properties of the planet. Assuming that the planet does radiate at our observation wavelength, its typical luminosity must be less than about 10^{16} W, unless its radiation is highly beamed into a solid angle Omega << 1 sr. While within the range of luminosities predicted by various authors for this planet, this value is lower than recent estimates which attempt to take into account...

  15. Initial deep LOFAR observations of epoch of reionization windows : I. The north celestial pole

    NARCIS (Netherlands)

    Yatawatta, S.; de Bruyn, A. G.; Brentjens, M. A.; Labropoulos, P.; Pandey, V. N.; Kazemi, S.; Zaroubi, S.; Koopmans, L. V. E.; Offringa, A. R.; Jelic, V.; Rubi, O. Martinez; Veligatla, V.; Wijnholds, S. J.; Brouw, W. N.; Bernardi, G.; Ciardi, B.; Daiboo, S.; Harker, G.; Schaye, J.; Thomas, R.; Vedantham, H.; Chapman, E.; Abdalla, F. B.; Alexov, A.; Anderson, J.; Avruch, I. M.; Batejat, F.; Bell, M. E.; Bell, M. R.; Bentum, M.; Best, P.; Bonafede, A.; Bregman, J.; Breitling, F.; van de Brink, R. H.; Broderick, J. W.; Brueggen, M.; Conway, J.; de Gasperin, F.; de Geus, E.; Duscha, S.; Falcke, H.; Fallows, R. A.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Griessmeier, J. M.; Gunst, A. W.; Hassall, T. E.; Hessels, J. W. T.; Hoeft, M.; Iacobelli, M.; Juette, E.; Karastergiou, A.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; van Leeuwen, J.; Maat, P.; Mann, G.; McKean, J. P.; Mevius, M.; Mol, J.D.; Munk, H.; Nijboer, R.; Noordam, J. E.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Rottgering, H. J. A.; Sluman, J.; Smirnov, O.; Stappers, B.; Steinmetz, M.; Tagger, M.; Tang, Y.; Tasse, C.; ter Veen, S.; Vermeulen, R.; van Weeren, R. J.; Wise, M.; Wucknitz, O.; Zarka, P.; Mellema, G.

    2013-01-01

    Aims. The aim of the LOFAR epoch of reionization (EoR) project is to detect the spectral fluctuations of the redshifted HI 21 cm signal. This signal is weaker by several orders of magnitude than the astrophysical foreground signals and hence, in order to achieve this, very long integrations, accurat

  16. The Influence of Epoch Length on Physical Activity Patterns Varies by Child's Activity Level

    Science.gov (United States)

    Nettlefold, Lindsay; Naylor, P. J.; Warburton, Darren E. R.; Bredin, Shannon S. D.; Race, Douglas; McKay, Heather A.

    2016-01-01

    Purpose: Patterns of physical activity (PA) and sedentary time, including volume of bouted activity, are important health indicators. However, the effect of accelerometer epoch length on measurement of these patterns and associations with health outcomes in children remain unknown. Method: We measured activity patterns in 308 children (52% girls,…

  17. Extreme Host Galaxy Growth in Powerful Early-epoch Radio Galaxies

    NARCIS (Netherlands)

    Barthel, Peter; Haas, Martin; Leipski, Christian; Wilkes, Belinda

    2012-01-01

    During the first half of the universe's life, a heyday of star formation must have occurred because many massive galaxies are in place after that epoch in cosmic history. Our observations with the revolutionary Herschel Space Observatory reveal vigorous optically obscured star formation in the ultra

  18. The Corporate University's Role in Managing an Epoch in Learning Organisation Innovation

    Science.gov (United States)

    Dealtry, Richard

    2006-01-01

    Purpose: The purpose of this paper is to set the scene for some radical epochal thinking about the approach and future strategic directions in the management of organisational learning, following the author's earlier editorial theme concerning the need for exploration and innovation in organisational learning management.…

  19. Initial deep LOFAR observations of epoch of reionization windows: I. The north celestial pole

    NARCIS (Netherlands)

    Yatawatta, S.; Bruyn, de A.G.; Brentjens, M.A.; Labropoulos, P.; Pandey, V.N.; Kazemi, S.; Zaroubi, S.; Koopmans, L.V.E.; Offringa, A.R.; Jelic, V.; Martinez Rubi, O.; Veligatla, V.; Wijnholds, S.J.; Brouw, W.N.; Bernardi, G.; Ciardi, B.; Daiboo, S.; Harker, G.; Mellema, G.; Schaye, J.; Thomas, R.; Vedantham, H.; Chapman, E.; Abdalla, F.B.; Alexov, A.; Anderson, J.; Avruch, I.M.; Batejat, F.; Bell, M.E.; Bell, M.R.; Bentum, M.J.; Best, P.; Bonafede, A.; Bregman, J.; Breitling, F.; Brink, van de R.H.; Broderick, J.W.; Brüggen, M.; Conway, J.; Gasperin, de F.; Geus, de E.; Duscha, S.; Falcke, H.; Fallows, R.A.; Ferrari, C.; Frieswijk, W.; Garrett, M.A.; Griessmeier, J.M.; Gunst, A.W.; Hassall, T.E.; Hessels, J.W.T.; Hoeft, M.; Iacobelli, M.; Juette, E.; Karastergiou, A.; Kondratiev, V.I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; Leeuwen, van J.; Maat, P.; Mann, G.; McKean, J.P.; Mevius, M.; Mol, J.D.; Munk, H.; Nijboer, R.; Noordam, J.E.; Norden, M.J.; Orrú, E.; Paas, H.; Pandey-Pommier, M.; Pizzo, R.; Polatidis, A.G.; Reich, W.; Röttgering, H.J.A.; Sluman, J.; Smirnov, O.; Stappers, B.; Steinmetz, M.; Tagger, M.; Tang, Y.; Tasse, C.; Veen, ter S.; Vermeulen, R.; Weeren, van R.J.; Wise, M.; Wucknitz, O.; Zarka, P.

    2013-01-01

    The aim of the LOFAR Epoch of Reionization (EoR) project is to detect the spectral fluctuations of the redshifted HI 21cm signal. This signal is weaker by several orders of magnitude than the astrophysical foreground signals and hence, in order to achieve this, very long integrations, accurate calib

  20. Initial deep LOFAR observations of epoch of reionization windows. I. The north celestial pole

    NARCIS (Netherlands)

    Yatawatta, S.; et al., [Unknown; Hessels, J.W.T.; van Leeuwen, J.; Wise, M.

    2013-01-01

    Aims. The aim of the LOFAR epoch of reionization (EoR) project is to detect the spectral fluctuations of the redshifted HI 21 cm signal. This signal is weaker by several orders of magnitude than the astrophysical foreground signals and hence, in order to achieve this, very long integrations, accurat

  1. Initial deep LOFAR observations of epoch of reionization windows. I. The north celestial pole

    NARCIS (Netherlands)

    Yatawatta, S.; de Bruyn, A. G.; Brentjens, M. A.; Labropoulos, P.; Pandey, V. N.; Kazemi, S.; Zaroubi, S.; Koopmans, L. V. E.; Offringa, A. R.; Jelić, V.; Martinez Rubi, O.; Veligatla, V.; Wijnholds, S. J.; Brouw, W. N.; Bernardi, G.; Ciardi, B.; Daiboo, S.; Harker, G.; Mellema, G.; Schaye, J.; Thomas, R.; Vedantham, H.; Chapman, E.; Abdalla, F. B.; Alexov, A.; Anderson, J.; Avruch, I. M.; Batejat, F.; Bell, M. E.; Bell, M. R.; Bentum, M.; Best, P.; Bonafede, A.; Bregman, J.; Breitling, F.; van de Brink, R. H.; Broderick, J. W.; Brüggen, M.; Conway, J.; de Gasperin, F.; de Geus, E.; Duscha, S.; Falcke, H.; Fallows, R. A.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Griessmeier, J. M.; Gunst, A. W.; Hassall, T. E.; Hessels, J. W. T.; Hoeft, M.; Iacobelli, M.; Juette, E.; Karastergiou, A.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; van Leeuwen, J.; Maat, P.; Mann, G.; McKean, J. P.; Mevius, M.; Mol, J. D.; Munk, H.; Nijboer, R.; Noordam, J. E.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Röttgering, H. J. A.; Sluman, J.; Smirnov, O.; Stappers, B.; Steinmetz, M.; Tagger, M.; Tang, Y.; Tasse, C.; ter Veen, S.; Vermeulen, R.; van Weeren, R. J.; Wise, M.; Wucknitz, O.; Zarka, P.

    2013-01-01

    Aims: The aim of the LOFAR epoch of reionization (EoR) project is to detect the spectral fluctuations of the redshifted HI 21 cm signal. This signal is weaker by several orders of magnitude than the astrophysical foreground signals and hence, in order to achieve this, very long integrations, accurat

  2. Importance of epoch length and registration time on accelerometer measurements in younger children

    DEFF Research Database (Denmark)

    Dencker, M; Svensson, J; El-Naaman, B

    2012-01-01

    The aim of this study was to investigate the effect of epoch length on accumulation of minutes of physical activity per day over a spectrum of intensities, and the effect that selection of number of hours of acceptable registration required per day had on number of days that were considered...

  3. Polarization leakage in epoch of reionization windows : The Low Frequency Array Case

    NARCIS (Netherlands)

    Asad, Khan

    2017-01-01

    The farther we look in space, the earlier we see in time. By observing a radio signal of 21cm wavelength coming from the epoch of reionization, when the universe was less than a billion years old, we can understand how the first stars, galaxies and black holes formed. This signal has not been detect

  4. Threshold in North Atlantic-Arctic circulation controlled by the Oligocene-Miocene subsidence of the Greenland-Scotland Ridge

    OpenAIRE

    Stärz, Michael; Jokat, Wilfried; Knorr, Gregor; Lohmann, Gerrit

    2016-01-01

    Changes in high latitude ocean gateways are thought to be main drivers of Cenozoic climate evolution. However, the link between global climate changes and the early ocean gateway formation between the North Atlantic and the Arctic Ocean (incl. the Greenland and Norwegian Seas) controlled by the subsidence of the Greenland-Scotland Ridge is poorly understood. Here, we use a coupled ocean–atmosphere general circulation model for Oligocene-Miocene boundary conditions to address the ventilation h...

  5. A late Eocene-early Oligocene transgressive event in the Golfo San Jorge basin: palynological results and stratigraphic implications

    OpenAIRE

    Paredes, José M.; Foix, Nicolas; Guerstein, Gladys Raquel; Guler, Maria Veronica; Irigoyen, Martin; Moscoso, Pablo; Giordano, Sergio

    2016-01-01

    A new Cenozoic dataset in the subsurface of the South Flank of the Golfo San Jorge Basin (Santa Cruz province) allowed to identify a non-previously recognized transgressive event of late Eocene to early Oligocene age. Below of a marine succession containing a dinoflagellate cyst assemblage that characterizes the C/G palynological zone of the Chenque Formation (early Miocene), a 80–110 m thick marine succession contains a palynological assemblage integrated by Gelatia inflata, Diphyes colliger...

  6. Taxonomy and palaeoecology of dinoflagellate cysts from Upper Oligocene freshwater sediments of Lake Enspel, Westerwald area, Germany.

    Science.gov (United States)

    Köhler; Clausing

    2000-10-01

    Freshwater dinoflagellates play an important role as primary producers in the lacustrine environment. A new species of dinoflagellates, Cleistosphaeridium lacustre, is described from Upper Oligocene sediments of palaeo-lake Enspel. They are associated with other phytoplankton, such as diatoms, chrysophytes, green algae and benthic cyanobacteria. Mass occurrences of this species are interpreted as algal blooms and may partly reflect seasonal successions. This phenomenon was controlled by volcanic activities in the depositional area, which led to an increase in nutrient supply.

  7. Sleep stage and obstructive apneaic epoch classification using single-lead ECG

    Directory of Open Access Journals (Sweden)

    Yılmaz Bülent

    2010-08-01

    Full Text Available Abstract Background Polysomnography (PSG is used to define physiological sleep and different physiological sleep stages, to assess sleep quality and diagnose many types of sleep disorders such as obstructive sleep apnea. However, PSG requires not only the connection of various sensors and electrodes to the subject but also spending the night in a bed that is different from the subject's own bed. This study is designed to investigate the feasibility of automatic classification of sleep stages and obstructive apneaic epochs using only the features derived from a single-lead electrocardiography (ECG signal. Methods For this purpose, PSG recordings (ECG included were obtained during the night's sleep (mean duration 7 hours of 17 subjects (5 men with ages between 26 and 67. Based on these recordings, sleep experts performed sleep scoring for each subject. This study consisted of the following steps: (1 Visual inspection of ECG data corresponding to each 30-second epoch, and selection of epochs with relatively clean signals, (2 beat-to-beat interval (RR interval computation using an R-peak detection algorithm, (3 feature extraction from RR interval values, and (4 classification of sleep stages (or obstructive apneaic periods using one-versus-rest approach. The features used in the study were the median value, the difference between the 75 and 25 percentile values, and mean absolute deviations of the RR intervals computed for each epoch. The k-nearest-neighbor (kNN, quadratic discriminant analysis (QDA, and support vector machines (SVM methods were used as the classification tools. In the testing procedure 10-fold cross-validation was employed. Results QDA and SVM performed similarly well and significantly better than kNN for both sleep stage and apneaic epoch classification studies. The classification accuracy rates were between 80 and 90% for the stages other than non-rapid-eye-movement stage 2. The accuracies were 60 or 70% for that specific stage

  8. The effect of epoch length on estimated EEG functional connectivity and brain network organisation

    Science.gov (United States)

    Fraschini, Matteo; Demuru, Matteo; Crobe, Alessandra; Marrosu, Francesco; Stam, Cornelis J.; Hillebrand, Arjan

    2016-06-01

    Objective. Graph theory and network science tools have revealed fundamental mechanisms of functional brain organization in resting-state M/EEG analysis. Nevertheless, it is still not clearly understood how several methodological aspects may bias the topology of the reconstructed functional networks. In this context, the literature shows inconsistency in the chosen length of the selected epochs, impeding a meaningful comparison between results from different studies. Approach. The aim of this study was to provide a network approach insensitive to the effects that epoch length has on functional connectivity and network reconstruction. Two different measures, the phase lag index (PLI) and the amplitude envelope correlation (AEC) were applied to EEG resting-state recordings for a group of 18 healthy volunteers using non-overlapping epochs with variable length (1, 2, 4, 6, 8, 10, 12, 14 and 16 s). Weighted clustering coefficient (CCw), weighted characteristic path length (L w) and minimum spanning tree (MST) parameters were computed to evaluate the network topology. The analysis was performed on both scalp and source-space data. Main results. Results from scalp analysis show a decrease in both mean PLI and AEC values with an increase in epoch length, with a tendency to stabilize at a length of 12 s for PLI and 6 s for AEC. Moreover, CCw and L w show very similar behaviour, with metrics based on AEC more reliable in terms of stability. In general, MST parameters stabilize at short epoch lengths, particularly for MSTs based on PLI (1-6 s versus 4-8 s for AEC). At the source-level the results were even more reliable, with stability already at 1 s duration for PLI-based MSTs. Significance. The present work suggests that both PLI and AEC depend on epoch length and that this has an impact on the reconstructed network topology, particularly at the scalp-level. Source-level MST topology is less sensitive to differences in epoch length, therefore enabling the comparison of brain

  9. A new species of Apidium (Anthropoidea, Parapithecidae) from the Sirt Basin, central Libya: First record of Oligocene primates from Libya.

    Science.gov (United States)

    Beard, K Christopher; Coster, Pauline M C; Salem, Mustafa J; Chaimanee, Yaowalak; Jaeger, Jean-Jacques

    2016-01-01

    A new species of Apidium is the most common primate currently known from a newly discovered site near Zallah Oasis in the Sirt Basin of central Libya. Based on current knowledge of the associated fauna, this new species of Apidium is early Oligocene in age, being roughly contemporaneous with faunas from Quarries G and V in the upper part of the Jebel Qatrani Formation in Egypt that also contain species of Apidium. A phylogenetic analysis based on dental characters indicates that the new species of Apidium from Libya is the sister group of Apidium phiomense. Apidium bowni and Apidium moustafai from the Jebel Qatrani Formation in the Fayum are similar in age to the new species of Apidium from Libya, but both of these Egyptian species are more distantly related to A. phiomense from younger stratigraphic levels in the Fayum. This phylogenetic pattern underscores the benefit of enhanced geographic sampling of the fossil record, even in cases where local records are thought to be reasonably comprehensive and well documented. Oligocene parapithecids can be partitioned into two clades corresponding to the subfamilies Parapithecinae (containing Parapithecus and Simonsius) and Qatraniinae (including Qatrania and Apidium). Climatic deterioration during the early Oligocene may have impacted the macroevolutionary dynamics of early Afro-Arabian anthropoids by fostering the fragmentation of forest habitats, thereby promoting allopatric speciation among widespread populations of Apidium and other arboreal taxa.

  10. A new Oligocene site with terrestrial mammals and a selachian fauna from Minqar Tibaghbagh, the Western Desert of Egypt

    Directory of Open Access Journals (Sweden)

    Hendrik Jan Van Vliet

    2017-09-01

    Full Text Available A new fossil site at Minqar Tibaghbagh, east of Siwa, in the Egyptian Western Desert is described. This represents the first place in Egypt outside the Fayum Depression yielding Paleogene, terrestrial mammals. Initial studies indicate the presence of palaeomastodonts, hyracoids, and anthracotheres, presumably early Oligocene in age. As only surface prospecting has been performed, more taxa will almost certainly be discovered in future investigations here and probably also elsewhere in the surroundings. A comparison is made with the most important contemporaneous sites in Libya and Egypt that yield terrestrial mammal remains. The selachian fauna from a higher level in the section confirms the Paleogene age of the subjacent strata. It is compared with selachians faunas from the early Oligocene Eastern Tethys Ocean at other places (the Fayum Depression in Egypt, and sites in Oman and Pakistan, and differs from these sites in being fully marine. Contrary to earlier studies, the open marine mudstones of the Daba’a Formation at Minqar Tibaghbagh are overlain by Paleogene marine sediments of most probably early Oligocene age and not early Miocene marine sediments as previously reported. These strata represent not only a new site with great potential for future finds, but also allows for biostratigraphic correlation.

  11. New Cricetid Rodents from Strata near the Eocene-Oligocene Boundary in Erden Obo Section (Nei Mongol, China.

    Directory of Open Access Journals (Sweden)

    Qian Li

    Full Text Available New cricetids (Eucricetodon wangae sp. nov., Eucricetodon sp. and Pappocricetodon siziwangqiensis sp. nov. are reported from the lower and middle parts of the "Upper Red" beds of the Erden Obo section in Nei Mongol, China. Eucricetodon wangae is more primitive than other known species of the genus from lower Oligocene of Asia and Europe in having a single anterocone on M1, a single connection between the protocone and the paracone, the anterior metalophule connection in M1-2 and weaker anteroconid and ectomesolophid in lower molars. Pappocricetodon siziwangqiensis is more advanced than other species of the genus in permanently missing P4 and having posterior protolophule connection. These fossils suggest that the age of the "Upper Red" of the Erden Obo section is younger than the age of the Upper Eocene Houldjin and Caijiachong formations, but older than those containing the Shandgolian faunas; the "Upper Red" is most closely correlative to the Ergilian beds in age, and probably close to the Eocene/Oligocene boundary. Given the age estimate, Eucricetodon wangae provides the new evidence to support that cricetid dispersal from Asia to Europe occurred prior to the Eocene-Oligocene boundary.

  12. Biostratigraphy and paleoecologic tolerances of Oligocene through Paleocene foraminiferal assemblages of the Gulf Coast Basin

    Energy Technology Data Exchange (ETDEWEB)

    Breard, S.Q.; Nault, M.J.; Callender, A.D. [Applied Biostratigraphix, Houston, TX (United States)

    1994-12-31

    Operationally oriented biostratigraphic and paleoecologic models are developed for Paleocene, Eocene, and Oligocene foraminifera of the Gulf Coast Basin. This paper is a companion to Breard et al. (1993), which describes models of significant paleoecologic and biostratigraphic foraminifera of the Miocene through Pleistocene of this region. Key benthic paleoenvironmental markers for particular depth zones of the Paleogene are graphically presented with updated biostratigraphic charts. Estimates of environment ranges for optimal stratigraphic utility are listed for all marker species on the biostratigraphic charts. Species depth ranges on the two biostratigraphic charts are for their zones of optimum stratigraphic utility. It is also possible to find deeper water species ranging into shallower zones in the lower bathyal to abyssal zones of the Eocene and Paleocene, where species considered characteristic of these zones range above those environments. Because relatively few wells have penetrated such deep environments in the Eocene and Paleocene, we have relied on the literature for Paleogene deep-water sections of Mexico and Trinidad to supplement our list of environmentally important species. Published material on foraminifera from deep-water Eocene and Paleocene sections penetrated in oil and gas exploration wells is almost nonexistent. Combination of data from this paper with that of Breard et al.(1993) will allow explorationists to estimate environmental tolerances for the entire Gulf Coast Cenozoic biostratigraphic column. This should serve as a predictive tool for foraminiferal studies useful in the exploration and production of oil and gas for the post-Mesozoic strata of the Gulf Coast basin and beyond.

  13. Swietenia (Meliaceae) flower in Late Oligocene Early Miocene amber from Simojovel de Allende, Chiapas, Mexico.

    Science.gov (United States)

    Castañeda-Posadas, Carlos; Cevallos-Ferriz, Sergio R S

    2007-11-01

    The amber of Simojovel de Allende, Chiapas, Mexico, of Late Oligocene-Early Miocene age, has yielded a new flower representing the Meliaceae. The flower of Swietenia miocenica Castañeda-Posadas & Cevallos-Ferriz sp. nov. is characterized by small size; free calyx composed of five glabrous lobes, ciliolated along the margin lobes; corolla composed of five free, contortedly inserted petals with ciliolated margins; cylindrical staminal tube ending in 10 acuminate or toothed accessories and 10 sessile anthers; and a discoid stigma divided in five lobular stigmatic glands. The morphology of S. miocenica is well represented among Meliaceae. Although the new species shares many characters with Swietenia microphylla, small differences in the length and width of petals and the length of staminal tube support its recognition as a new species. The presence of this genus demonstrates the establishment of tropical communities in southern Mexico by the early Miocene and highlights the influence of the northern hemisphere flora on the extant neotropical flora of the area.

  14. LITHOSTRATIGRAPHY AND FACIES ARCHITECTURE OF THE OLIGOCENE CONGLOMERATES AT MONTE PAREI (FANES. DOLOMITES, ITALY

    Directory of Open Access Journals (Sweden)

    LORENZ KEIM

    2000-03-01

    Full Text Available The only occurrence of Tertiary (Oligocene sediments in the Dolomites at Monte Parei results from a complex tectonic and sedimentary history. The Tertiary marine clastic succession is sealing the Dinaric (Late Cretaceous to Paleogene deformed basement. The basin-fill can be differentiated into four lithofacies which show extensive lateral interfingering: ,local scarp breccias with giant blocks (facies A, chaotic breccias of debris flow origin (facies B, balanid and shell coquina beds (facies C and conglomeratic grain and debris flows with sandstone intercalations (facies D. Transport directions (imbricate clasts and cross bedding and petrographic composition indicate two different source areas. Sediments of facies B were shed from a structural high in the SW, while carbonate-siliciclastic debris of facies C and D originated from a pebbly or rocky shore in the N. Lithofacies and facies interrelationships clearly indicate the control by synsedimentary tectonic activity. Neoalpine closure of the basin by overthrusting lead to the preservation of the sediments. 

  15. Diagenesis of Oligocene continental sandstones in salt-walled mini-basins-Sivas Basin, Turkey

    Science.gov (United States)

    Pichat, Alexandre; Hoareau, Guilhem; Callot, Jean-Paul; Ringenbach, Jean-Claude

    2016-06-01

    The recent discovery of Oligo-Miocene salt-walled continental mini-basins in the Sivas Basin (central Anatolia, Turkey) provides the opportunity to unravel the influence of halokinesis on the diagenesis of continental mini-basin infilling. In this study, petrographic and geochemical analyses are used to define the diagenetic sequences recorded by two mini-basins filled mainly by fluvial clastic sediments of the upper Oligocene Karayün Formation. The initial diagenetic features are those commonly encountered in arid to semi-arid continental environments, i.e. clay infiltration, hematite precipitation and vadose calcite cement. Other early cements were strongly controlled by sandstone detrital composition in the presence of saline/alkaline pore water. In feldspathic litharenites and lithic arkoses, near-surface alterations were characterized by the precipitation of analcime (up to 10%), albite and quartz overgrowths (burial diagenesis which prevented further mesogenetic alteration phenomena such as compaction. In feldsarenites, early diagenesis differs by (i) the absence of analcime, (ii) better developed albite cements, (iii) thin smectite-illite coatings forming pore linings and (iv) patchy calcite cementation (burial, and result in a significant degradation of porosity.

  16. CALCAREOUS ALGAE FROM THE LOWER OLIGOCENE GORNJI GRAD BEDS OF NORTHERN SLOVENIA

    Directory of Open Access Journals (Sweden)

    DAVIDE BASSI

    2000-03-01

    Full Text Available This paper presents the first systematic account of calcareous algae from the limestones of the Lower Oligocene Gornji Grad beds of northern Slovenia. These bioclastic limestones are dominated by different coralline algal assemblages as well as corals, large and small benthic foraminifera as well as bivalves. The taxonomy and growth-forms of eleven species of seven non-geniculate coralline algal genera are described: Lithoporella, Neogoniolithon, Spongites, Lithothamnion, Mesophyllum, Sporolithon, Subterraniphyllum,. Additionally, the genera Polystrata (Peyssonneliaceae Halimeda (Halimedaceae, and Cymopolia (Dasycladaceae are present. The taxonomic interpretation of fossil coralline material in a manner consistent with generic and specific concepts currently in use for Recent material is, at present, difficult. In the absence of comparative studies on type material, only limited comparisons are possible, and in most cases definitive taxonomic conclusions cannot be reached. Most of the species designations are thus made following and open nomenclature, pending the rigorous taxonomic revision of historically established, fossil coralline algal species. The present study reveals a considerable variation of growth-form morphologies at both genus and species levels. This demonstrates the difficulties in using this feature as a diagnostic character in the identification of fossil coralline red algal taxa. 

  17. Neotropics provide insights into the emergence of New World monkeys: New dental evidence from the late Oligocene of Peruvian Amazonia.

    Science.gov (United States)

    Marivaux, Laurent; Adnet, Sylvain; Altamirano-Sierra, Ali J; Boivin, Myriam; Pujos, François; Ramdarshan, Anusha; Salas-Gismondi, Rodolfo; Tejada-Lara, Julia V; Antoine, Pierre-Olivier

    2016-08-01

    Recent field efforts in Peruvian Amazonia (Contamana area, Loreto Department) have resulted in the discovery of a late Oligocene (ca. 26.5 Ma; Chambira Formation) fossil primate-bearing locality (CTA-61). In this paper, we analyze the primate material consisting of two isolated upper molars, the peculiar morphology of which allows us to describe a new medium-sized platyrrhine monkey: Canaanimico amazonensis gen. et sp. nov. In addition to the recent discovery of Perupithecus ucayaliensis, a primitive anthropoid taxon of African affinities from the alleged latest Eocene Santa Rosa locality (Peruvian Amazonia), the discovery of Canaanimico adds to the evidence that primates were well-established in the Amazonian Basin during the Paleogene. Our phylogenetic results based on dental evidence show that none of the early Miocene Patagonian taxa (Homunculus, Carlocebus, Soriacebus, Mazzonicebus, Dolichocebus, Tremacebus, and Chilecebus), the late Oligocene Bolivian Branisella, or the Peruvian Canaanimico, is nested within a crown platyrrhine clade. All these early taxa are closely related and considered here as stem Platyrrhini. Canaanimico is nested within the Patagonian Soriacebinae, and closely related to Soriacebus, thereby extending back the soriacebine lineage to 26.5 Ma. Given the limited dental evidence, it is difficult to assess if Canaanimico was engaged in a form of pitheciine-like seed predation as is observed in Soriacebus and Mazzonicebus, but dental microwear patterns recorded on one upper molar indicate that Canaanimico was possibly a fruit and hard-object eater. If Panamacebus, a recently discovered stem cebine from the early Miocene of Panama, indicates that the crown platyrrhine radiation was already well underway by the earliest Miocene, Canaanimico indicates in turn that the "homunculid" radiation (as a part of the stem radiation) was well underway by the late Oligocene. These new data suggest that the stem radiation likely occurred in the Neotropics

  18. trash epoch

    Directory of Open Access Journals (Sweden)

    Elena Grigoryeva

    2012-02-01

    Full Text Available Unconventionally, the editorial of this issue begins with two epigraphs:trash1. foolish ideas or talk; nonsense;2. Chiefly US and Canadian useless or unwanted matter or objects;3. a literary or artistic production of poor quality;4. Chiefly US and Canadian a poor or worthless person or a group of such people.[Collins English Dictionary]You got to make good out of bad. That's all there is to make it with. Robert Penn Warren, “All the King’s Men”.But before talking about the topic of the issue, we should pay off the debt. The previous (double issue was completely devoted to Irkutsk’s jubilee. We will fill in the gaps and look back on the events of the past year missed by PB. There are a lot of them: the UIA Congress in Tokyo (5-7, the Zodchestvo Festival and the UAR Plenary Meeting in Moscow (16-29, the review competition of graduation works in Erevan (30–39 and Les Ateliers of Urban Planning and Development in Cergy-Pontoise (48–54.The New Year’s news blends into the topic of the issue. This year in Irkutsk discarded Christmas trees began to be recycled into fertilizer. In the Kemerovo region the old Christmas trees are used as food for cows. So the supercilious attitude toward trash is no longer relevant. In the future we shall eat it; actually, we are already eating it. Artists help us adjust to the idea that we will live in the global dump. Trash Muses inspired Zhenya Kraineva and Konstantin Lidin to a diptych about trash art (66–75.The first essential step in waste recycling is to change our view on waste. In people’s minds the dump is turned into a deposit of valuable resources. The detailed text by Andrei Ivanov (90–99 tells us about a slum district obtaining a new status and turning into a historical heritage.It is very urgent to convert trash into resources. On the Earth, mountains of garbage grow twice as fast as the population. 17% of homes in Sweden are heated with garbage. Japan processes 96% of waste, Germany 95%, Poland 16%, Russia only 5%. At this moment the territory of Russia has accumulated 100 billion tons of garbage – there is scarcely any deposit of such a large scale. Waste recycling plants are a vital task for today’s and tomorrow’s architecture (102–105.The architecture itself is no longer designed for centuries. The green standards contain such an essential item as engineering redesign for dismantled or demolished structures. Instead of the philosophical principle “my house is my fortress”, the impermanence is on the agenda today. A house, like a short-life packing or tomorrow’s garbage, is now under the statement of the problem.This issue returns to its regular sections. In the HERITAGE section there is an article by our American contributor Brian Spencer (124–129; and a debut of Fabio Todeschini, Professor from South Africa (130–136. In the LANDSCAPE section we start publishing a series of articles by Olga Smirnova (142–147, a Krasnoyarsk architect, poet and traveler…

  19. trash epoch

    OpenAIRE

    Elena Grigoryeva

    2012-01-01

    Unconventionally, the editorial of this issue begins with two epigraphs:trash1. foolish ideas or talk; nonsense;2. Chiefly US and Canadian useless or unwanted matter or objects;3. a literary or artistic production of poor quality;4. Chiefly US and Canadian a poor or worthless person or a group of such people.[Collins English Dictionary]You got to make good out of bad. That's all there is to make it with. Robert Penn Warren, “All the King’s Men”.But before talking about the topic of the issue,...

  20. Stratigraphy, geochemistry and tectonic significance of the Oligocene magmatic rocks of western Oaxaca, southern Mexico

    Science.gov (United States)

    Martiny, B.; Martinez-Serrano, R. G.; Moran-Zenteno, D. J.; MacIas-Romo, C.; Ayuso, R.A.

    2000-01-01

    In Western Oaxaca, Tertiary magmatic activity is represented by extensive plutons along the continental margin and volcanic sequences in the inland region. K-Ar age determinations reported previously and in the present work indicate that these rocks correspond to a relatively broad arc in this region that was active mainly during the Oligocene (~ 35 to ~ 25 Ma). In the northern sector of western Oaxaca (Huajuapan-Monte Verde-Yanhuitlan), the volcanic suite comprises principally basaltic andesite to andesitic lavas, overlying minor silicic to intermediate volcaniclastic rocks (epiclastic deposits, ash fall tuffs, ignimbrites) that were deposited in the lacustrine-fluvial environment. The southern sector of the volcanic zone includes the Tlaxiaco-Laguna de Guadalupe region and consists of intermediate to silicic pyroclastic and epiclastic deposits, with silicic ash fall tuffs and ignimbrites. In both sectors, numerous andesitic to dacitic hypabyssal intrusions (stocks and dikes) were emplaced at different levels of the sequence. The granitoids of the coastal plutonic belt are generally more differentiated than the volcanic rocks that predominate in the northern sector and vary in composition from granite to granodiorite. The studied rocks show large-ion lithophile element (LILE) enrichment (K, Rb, Ba, Th) relative to high-field-strength (HFS) elements (Nb, Ti, Zr) that is characteristic of subduction-related magmatic rocks. On chondrite-normalized rare earth element diagrams, these samples display light rare earth element enrichment (LREE) and a flat pattern for the heavy rare earth elements (HREE). In spite of the contrasting degree of differentiation between the coastal plutons and inland volcanic rocks, there is a relatively small variation in the isotopic composition of these two suites. Initial 87Sr/86Sr ratios obtained and reported previously for Tertiary plutonic rocks of western Oaxaca range from 0.7042 to 0.7054 and ??Nd values, from -3.0 to +2.4, and for

  1. Occurrence of gas hydrate in Oligocene Frio sand: Alaminos Canyon Block 818: Northern Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Boswell, R.D.; Shelander, D.; Lee, M.; Latham, T.; Collett, T.; Guerin, G.; Moridis, G.; Reagan, M.; Goldberg, D.

    2009-07-15

    A unique set of high-quality downhole shallow subsurface well log data combined with industry standard 3D seismic data from the Alaminos Canyon area has enabled the first detailed description of a concentrated gas hydrate accumulation within sand in the Gulf of Mexico. The gas hydrate occurs within very fine grained, immature volcaniclastic sands of the Oligocene Frio sand. Analysis of well data acquired from the Alaminos Canyon Block 818 No.1 ('Tigershark') well shows a total gas hydrate occurrence 13 m thick, with inferred gas hydrate saturation as high as 80% of sediment pore space. Average porosity in the reservoir is estimated from log data at approximately 42%. Permeability in the absence of gas hydrates, as revealed from the analysis of core samples retrieved from the well, ranges from 600 to 1500 millidarcies. The 3-D seismic data reveals a strong reflector consistent with significant increase in acoustic velocities that correlates with the top of the gas-hydrate-bearing sand. This reflector extends across an area of approximately 0.8 km{sup 2} and delineates the minimal probable extent of the gas hydrate accumulation. The base of the inferred gas-hydrate zone also correlates well with a very strong seismic reflector that indicates transition into units of significantly reduced acoustic velocity. Seismic inversion analyses indicate uniformly high gas-hydrate saturations throughout the region where the Frio sand exists within the gas hydrate stability zone. Numerical modeling of the potential production of natural gas from the interpreted accumulation indicates serious challenges for depressurization-based production in settings with strong potential pressure support from extensive underlying aquifers.

  2. Southern Tibetan Oligocene-Miocene adakites: A record of Indian slab tearing

    Science.gov (United States)

    Zhang, Li-Yun; Ducea, Mihai N.; Ding, Lin; Pullen, Alex; Kapp, Paul; Hoffman, Derek

    2014-12-01

    Oligocene-Miocene granitoids exposed within the 1500-km-long Gangdese arc of southern Tibet exhibit adakitic compositions. Five plutonic samples from the southeastern Lhasa terrane near Namche Barwa area were analyzed to determine their geochemical characteristics and to better understand the geodynamic evolution of the eastern Himalayan syntaxis orogen. The samples, yielded U-Pb zircon ages in the range of 30-26 Ma, are intermediate to silicic in composition and have elevated K2O (1.5-8.9), Th/La ratios (0.14-1.10), low MgO (< 2%) and Mg# (< 50), as well as high initial 87Sr/86Sri (0.7062-0.7103) and low εNd(t) (- 10.9 to - 1.0) isotopic compositions. In addition, these granitic and granodioritic rocks have high Sr/Y (66-306) and La/Yb (25-312) ratios, a characteristic of adakitic rocks. In-situ zircon εHf(t) isotopic compositions are in the range of + 8.1 to - 1.9. Within the framework of the Tibetan-Himalayan orogenesis we attribute these rocks to represent partial melting and mixing products of two end-member components of the lower Tibetan crust: the roots of the relatively juvenile Gangdese arc crust and newly-underplated high-potassium mafic magmas. Adakitic magmatism initiated at 30-26 Ma near the eastern Himalayan syntaxis and systematically decreases in age to the west to 18-9 Ma near Shigatse. We attribute this temporal-spatial distribution of adakitic magmatism within the Gangdese arc, along with the regional Oligo-Miocene geology, to the progressive tearing of the Indian plate. Based on the decrease in age of adakitic magmatism from east to west we hypothesize that the tear initiated beneath the eastern Himalayan syntaxis and propagated westward.

  3. A remarkable female cranium of the early Oligocene anthropoid Aegyptopithecus zeuxis (Catarrhini, Propliopithecidae).

    Science.gov (United States)

    Simons, Elwyn L; Seiffert, Erik R; Ryan, Timothy M; Attia, Yousry

    2007-05-22

    The most complete and best-preserved cranium of a Paleogene anthropoid ever found, that of a small female of the early Oligocene ( approximately 29-30 Ma) stem catarrhine species Aegyptopithecus zeuxis, was recovered from the Jebel Qatrani Formation (Fayum Depression, Egypt) in 2004. The specimen is that of a subadult and, in craniodental dimensions, is the smallest Aegyptopithecus individual known. High-resolution computed tomographic (microCT) scanning of the specimen's well preserved cranial vault confirms that Aegyptopithecus had relatively unexpanded frontal lobes and a brain-to-body mass ratio lower than those of living anthropoids. MicroCT scans of a male cranium recovered in 1966 [Egyptian Geological Museum, Cairo (CGM) 40237] reveal that previous estimates of its endocranial volume were too large. Thus, some amount of encephalization evolved independently in platyrrhine and catarrhine anthropoids, and the relative brain size of the last common ancestor of crown Anthropoidea was probably strepsirrhine-like or smaller. A. zeuxis shows extreme sexual dimorphism in craniodental morphology (apparently to a degree otherwise seen only in some highly dimorphic Miocene catarrhines), and the crania of female Aegyptopithecus lack a number of morphological features seen in larger males that have been accorded phylogenetic significance in catarrhine systematics (e.g., a well developed rostrum, elongate sagittal crest, and frontal trigon). Although a unique pattern of craniofacial sexual dimorphism may have characterized advanced stem and basal crown catarrhines, expression of various allegedly "discrete" craniofacial features may have been intraspecifically variable in early catarrhine species due to high levels of dimorphism and so should be treated with caution in phylogenetic analyses.

  4. Occurrence of gas hydrate in Oligocene Frio sand: Alaminos Canyon Block 818: Northern Gulf of Mexico

    Science.gov (United States)

    Boswell, R.; Shelander, D.; Lee, M.; Latham, T.; Collett, T.; Guerin, G.; Moridis, G.; Reagan, M.; Goldberg, D.

    2009-01-01

    A unique set of high-quality downhole shallow subsurface well log data combined with industry standard 3D seismic data from the Alaminos Canyon area has enabled the first detailed description of a concentrated gas hydrate accumulation within sand in the Gulf of Mexico. The gas hydrate occurs within very fine grained, immature volcaniclastic sands of the Oligocene Frio sand. Analysis of well data acquired from the Alaminos Canyon Block 818 #1 ("Tigershark") well shows a total gas hydrate occurrence 13??m thick, with inferred gas hydrate saturation as high as 80% of sediment pore space. Average porosity in the reservoir is estimated from log data at approximately 42%. Permeability in the absence of gas hydrates, as revealed from the analysis of core samples retrieved from the well, ranges from 600 to 1500 millidarcies. The 3-D seismic data reveals a strong reflector consistent with significant increase in acoustic velocities that correlates with the top of the gas-hydrate-bearing sand. This reflector extends across an area of approximately 0.8??km2 and delineates the minimal probable extent of the gas hydrate accumulation. The base of the inferred gas-hydrate zone also correlates well with a very strong seismic reflector that indicates transition into units of significantly reduced acoustic velocity. Seismic inversion analyses indicate uniformly high gas-hydrate saturations throughout the region where the Frio sand exists within the gas hydrate stability zone. Numerical modeling of the potential production of natural gas from the interpreted accumulation indicates serious challenges for depressurization-based production in settings with strong potential pressure support from extensive underlying aquifers.

  5. Provenance analysis of the Oligocene turbidites (Andaman Flysch), South Andaman Island: A geochemical approach

    Indian Academy of Sciences (India)

    P C Bandopadhyay; Biswajit Ghosh

    2015-07-01

    The Oligocene-aged sandstone-shale turbidites of the Andaman Flysch are best exposed along the east coast of the South Andaman Island. Previously undocumented sandstone-shale geochemistry, investigated here, provides important geochemical constraints on turbidite provenance. The average 70.75 wt% SiO2, 14.52 wt% Al2O3, 8.2 wt% Fe2O$^{\\text{t}}_{3}$+MgO and average 0.20 Al2O3/SiO2 and 1.08 K2O/Na2O ratios in sandstones, compare with quartzwackes. The shale samples have average 59.63 wt% SiO2, 20.29 wt% Al2O3, 12.63 wt% Fe2O$^{\\text{t}}_{3}$+MgO and average 2.42 K2O/Na2O and 0.34 Al2O3/SiO2 ratios. Geochemical data on CaO–Na2O–K2O diagram fall close to a granite field and on K2O/Na2O–SiO2 diagram within an active continental margin tectonic setting. The range and average values of Rb and Rb/Sr ratios are consistent with acid-intermediate igneous source rocks, while the values and ratios for Cr and Ni are with mafic rocks. Combined geochemical, petrographic and palaeocurrent data indicate a dominantly plutonic-metamorphic provenance with a lesser contribution from sedimentary and volcanic source, which is possibly the Shan–Thai continental block and volcanic arc of the north-eastern and eastern Myanmar. Chemical index of alteration (CIA) values suggests a moderate range of weathering of a moderate relief terrane under warm and humid climate.

  6. Energy dissipation of energetic electrons in the inhomogeneous intergalactic medium during the epoch of reionization

    CERN Document Server

    Kaurov, Alexander A

    2015-01-01

    We explore a time-dependent energy dissipation of the energetic electrons in the inhomogeneous intergalactic medium (IGM) during the epoch of cosmic reionization. In addition to the atomic processes we take into account the Inverse Compton (IC) scattering of the electrons on the comic microwave background (CMB) photons, which is the dominant channel of energy loss for the electrons with energies above a few MeV. We show that: (1) the effect on the IGM has both local (atomic processes) and non-local (IC radiation) components; (2) the energy distribution between Hydrogen and Helium ionizations depends on the initial electron energy; (3) the local baryon overdensity significantly affects the fractions of energy distributed in each channel; and (4) the relativistic effect of atomic cross section become important during the epoch of cosmic reionization. We release our code as open source for further modification by the community.

  7. A new approach of single epoch GPS positioning for landslide monitoring

    Institute of Scientific and Technical Information of China (English)

    LIU Gen-you; ZHU Yao-zhong; ZHOU Rong-sheng

    2005-01-01

    When the deformation of landslide becomes larger, the conventional static GPS surveying cannot satisfy the real-time requirement in landslide monitoring. In this paper we present a new method for single epoch GPS positioning combining with the accuracy of approximate coordinates of monitored station in landslide monitoring. This algorithm does not consider troublesome cycle-slip problem of carrier phase, and integer ambiguities can be solved at a single epoch, so the centimeter level accurate coordinates can be calculated instantaneously. By means of filtering or smoothing, this method can be extended to detect millimeter level deformation and velocity. In order to test the new method, low-cost single frequency receivers have been used in a real landslide, which happened in Jiangxi Province, China.

  8. Pulsar B2224+65 and Jets: A Two Epoch X-ray Analysis

    CERN Document Server

    Johnson, S P

    2010-01-01

    We present an X-ray morphological and spectroscopic study of the pulsar B2224+65 and its apparent jet-like X-ray features based on two epoch Chandra observations. The main X-ray feature, which shows a large directional offset from the ram-pressure confined pulsar wind nebula (Guitar Nebula), is broader in apparent width and more luminous in the second epoch than the first. Furthermore, the sharp leading edge is found to have a proper motion consistent with that of the pulsar (~180 mas/yr). The combined data set also provides evidence for the presence of a counter feature, albeit substantially fainter and shorter than the main one. These results are consistent with a simple model of relativistic jet outflow originating from the pulsar and ram-pressure confined by the unusually rapid motion of the pulsar.

  9. THE EFFECTS OF POLARIZED FOREGROUNDS ON 21 cm EPOCH OF REIONIZATION POWER SPECTRUM MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Moore, David F.; Aguirre, James E. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA (United States); Parsons, Aaron R.; Pober, Jonathan C. [Astronomy Department, University of California, Berkeley, Berkeley, CA (United States); Jacobs, Daniel C., E-mail: damo@sas.upenn.edu [School of Earth and Space Exploration, Arizona State University, Tempe, AZ USA (United States)

    2013-06-01

    Experiments aimed at detecting highly-redshifted 21 cm emission from the epoch of reionization (EoR) are plagued by the contamination of foreground emission. A potentially important source of contaminating foregrounds may be Faraday-rotated, polarized emission, which leaks into the estimate of the intrinsically unpolarized EoR signal. While these foregrounds' intrinsic polarization may not be problematic, the spectral structure introduced by the Faraday rotation could be. To better understand and characterize these effects, we present a simulation of the polarized sky between 120 and 180 MHz. We compute a single visibility, and estimate the three-dimensional power spectrum from that visibility using the delay spectrum approach presented in Parsons et al. Using the Donald C. Backer Precision Array to Probe the Epoch of Reionization as an example instrument, we show the expected leakage into the unpolarized power spectrum to be several orders of magnitude above the expected 21 cm EoR signal.

  10. Multi-epoch BVRI Photometry of Luminous Stars in M31 and M33

    Science.gov (United States)

    Martin, John C.; Humphreys, Roberta M.; pre="(">Minnesota Luminous Stars In Nearby Galaxies,

    2017-09-01

    We present the first four years of BVRI photometry from an on-going survey to annually monitor the photometric behavior of evolved luminous stars in M31 and M33. Photometry was measured for 199 stars at multiple epochs, including 9 classic Luminous Blue Variables (LBVs), 22 LBV candidates, 10 post-RGB A/F type hypergiants, and 18 B[e] supergiants. At all epochs, the brightness is measured in the V-band and at least one other band to a precision of 0.04-0.10 mag down to a limiting magnitude of 19.0-19.5. Thirty three stars in our survey exhibit significant variability, including at least two classic LBVs caught in S Doradus-type outbursts. A hyperlinked version of the photometry catalog is at http://go.uis.edu/m31m33photcat.

  11. The Effect of Interplanetary Scintillation on Epoch of Reionisation Power Spectra

    OpenAIRE

    Trott, Cathryn M.; Tingay, Steven J.

    2015-01-01

    Interplanetary Scintillation (IPS) induces intensity fluctuations in small angular size astronomical radio sources via the distortive effects of spatially and temporally varying electron density associated with outflows from the Sun. These radio sources are a potential foreground contaminant signal for redshifted HI emission from the Epoch of Reionisation (EoR) because they yield time-dependent flux density variations in bright extragalactic point sources. Contamination from foreground contin...

  12. Contamination of the Epoch of Reionization power spectrum in the presence of foregrounds

    OpenAIRE

    Sims, Peter H.; Lentati, Lindley; Alexander, Paul; Carilli, Chris L.

    2016-01-01

    We construct foreground simulations comprising spatially correlated extragalactic and diffuse Galactic emission components and calculate the `intrinsic' (instrument-free) two-dimensional spatial power spectrum and the cylindrically and spherically averaged three-dimensional k-space power spectra of the Epoch of Reionization (EoR) and our foreground simulations using a Bayesian power spectral estimation framework. This leads us to identify a model dependent region of optimal signal estimation ...

  13. Will Nonlinear Peculiar Velocity and Inhomogeneous Reionization Spoil 21cm Cosmology from the Epoch of Reionization?

    OpenAIRE

    Shapiro, Paul R.; Mao, Yi; Iliev, Ilian T.; Mellema, Garrelt; Datta, Kanan K.; Ahn, Kyungjin; Koda, Jun

    2012-01-01

    The 21cm background from the epoch of reionization is a promising cosmological probe: line-of-sight velocity fluctuations distort redshift, so brightness fluctuations in Fourier space depend upon angle, which linear theory shows can separate cosmological from astrophysical information. Nonlinear fluctuations in ionization, density and velocity change this, however. The validity and accuracy of the separation scheme are tested here for the first time, by detailed reionization simulations. The ...

  14. Solar wind conditions leading to efficient radiation belt electron acceleration: A superposed epoch analysis

    OpenAIRE

    Li, W; Thorne, RM; Bortnik, J.; Baker, DN; Reeves, GD; Kanekal, SG; Spence, HE; Green, JC

    2015-01-01

    ©2015. American Geophysical Union. All Rights Reserved. Determining preferential solar wind conditions leading to efficient radiation belt electron acceleration is crucial for predicting radiation belt electron dynamics. Using Van Allen Probes electron observations ( > 1 MeV) from 2012 to 2015, we identify a number of efficient and inefficient acceleration events separately to perform a superposed epoch analysis of the corresponding solar wind parameters and geomagnetic indices. By directly c...

  15. The Lick AGN Monitoring Project: Recalibrating Single-Epoch Virial Black Hole Mass Estimates

    CERN Document Server

    Park, Daeseong; Treu, Tommaso; Barth, Aaron J; Bentz, Misty C; Bennert, Vardha N; Canalizo, Gabriela; Filippenko, Alexei V; Gates, Elinor; Greene, Jenny E; Malkan, Matthew A; Walsh, Jonelle

    2011-01-01

    We investigate the calibration and uncertainties of black hole mass estimates based on the single-epoch (SE) method, using homogeneous and high-quality multi-epoch spectra obtained by the Lick Active Galactic Nucleus (AGN) Monitoring Project for 9 local Seyfert 1 galaxies with black hole masses < 10^8 M_sun. By decomposing the spectra into their AGN and stellar components, we study the variability of the single-epoch Hbeta line width (full width at half-maximum intensity, FWHM_Hbeta; or dispersion, sigma_Hbeta) and of the AGN continuum luminosity at 5100A (L_5100). From the distribution of the "virial products" (~ FWHM_Hbeta^2 L_5100^0.5 or sigma_Hbeta^2 L_5100^0.5) measured from SE spectra, we estimate the uncertainty due to the combined variability as ~ 0.05 dex (12%). This is subdominant with respect to the total uncertainty in SE mass estimates, which is dominated by uncertainties in the size-luminosity relation and virial coefficient, and is estimated to be ~ 0.46 dex (factor of ~ 3). By comparing the...

  16. THE TIME EVOLUTION OF HH 1 FROM FOUR EPOCHS OF HST IMAGES

    Energy Technology Data Exchange (ETDEWEB)

    Raga, A. C.; Esquivel, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Ap. 70-543, 04510 D.F., México (Mexico); Reipurth, B. [Institute for Astronomy, University of Hawaii at Manoa, Hilo, HI 96720 (United States); Bally, J., E-mail: raga@nucleares.unam.mx [Center for Astrophysics and Space Astronomy, University of Colorado, UCB 389, Boulder, CO 80309 (United States)

    2016-05-15

    We present an analysis of four epochs of Hα and [S ii] λλ 6716/6731 Hubble Space Telescope (HST) images of HH 1. For determining proper motions, we explore a new method based on the analysis of spatially degraded images obtained convolving the images with wavelet functions of chosen widths. With this procedure, we are able to generate maps of proper motion velocities along and across the outflow axis, as well as (angularly integrated) proper motion velocity distributions. From the four available epochs, we find the time evolution of the velocities, intensities, and spatial distribution of the line emission. We find that over the last two decades HH 1 shows a clear acceleration. Also, the Hα and [S ii] intensities first dropped and then recovered in the more recent (2014) images. Finally, we show a comparison between the two available HST epochs of [O iii] λ 5007 (1994 and 2014), in which we see a clear drop in the value of the [O iii]/Hα ratio.

  17. The Hydrogen Epoch of Reionization Array Dish I: Beam Pattern Measurements and Science Implications

    CERN Document Server

    Neben, Abraham R; Hewitt, Jacqueline N; DeBoer, David R; Parsons, Aaron R; Aguirre, James E; Ali, Zaki S; Cheng, Carina; Ewall-Wice, Aaron; Patra, Nipanjana; Thyagarajan, Nithyanandan; Bowman, Judd; Dickenson, Roger; Dillon, Joshua S; Doolittle, Phillip; Egan, Dennis; Hedrick, Mike; Jacobs, Daniel C; Kohn, Saul A; Klima, Patricia J; Moodley, Kavilan; Saliwanchik, Benjamin R B; Schaffner, Patrick; Shelton, John; Taylor, H A; Taylor, Rusty; Tegmark, Max; Wirt, Butch; Zheng, Haoxuan

    2016-01-01

    The Hydrogen Epoch of Reionization Array (HERA) is a radio interferometer aiming to detect the power spectrum of 21cm fluctuations from neutral hydrogen from the Epoch of Reionization (EOR). Drawing on lessons from the Murchison Widefield Array (MWA) and the Precision Array for Probing the Epoch of Reionization (PAPER), HERA is a hexagonal array of large (14m diameter) dishes with suspended dipole feeds. Not only does the dish determine overall sensitivity, it affects the observed frequency structure of foregrounds in the interferometer. This is the first of a series of four papers characterizing the frequency and angular response of the dish with simulations and measurements. We focus in this paper on the angular response (i.e., power pattern), which sets the relative weighting between sky regions of high and low delay, and thus, apparent source frequency structure. We measure the angular response at 137MHz using the ORBCOMM beam mapping system of Neben et al. We measure a collecting area of 93m^2 in the opt...

  18. The time evolution of HH 1 from four epochs of HST images

    CERN Document Server

    Raga, A C; Esquivel, A; Bally, J

    2016-01-01

    We present an analysis of four epochs of H$\\alpha$ and [S II] $\\lambda\\lambda$ 6716/6731 HST images of HH 1. For determining proper motions we explore a new method based on analysis of spatially degraded images obtained convolving the images with wavelet functions of chosen widths. With this procedure we are able to generate maps of proper motion velocities along and across the outflow axis, as well as (angularly integrated) proper motion velocity distributions. From the four available epochs, we find the time evolution of the velocities, intensities and spatial distribution of the line emission. We find that over the last two decades HH 1 shows a clear acceleration. Also, the H$\\alpha$ and [S II] intensities have first dropped, and then recovered in the more recent (2014) images. Finally, we show a comparison between the two available HST epochs of [O III] $\\lambda$ 5007 (1994 and 2014), in which we see a clear drop in the value of the [O III]/H$\\alpha$ ratio.

  19. Use of Apollo 17 Epoch Neutron Spectrum as a Benchmark in Testing LEND Collimated Sensor

    Science.gov (United States)

    Chin, Gordon; Sagdeev, R.; Milikh, G.

    2011-01-01

    The Apollo 17 neutron experiment LPNE provided a unique set of data on production of neutrons in the Lunar soil bombarded by Galactic Cosmic Rays (GCR). It serves as valuable "ground-truth" in the age of orbital remote sensing. We used the neutron data attributed to Apollo 17 epoch as a benchmark for testing the LEND's collimated sensor, as introduced by the geometry of collimator and efficiency of He3 counters. The latter is defined by the size of gas counter and pressure inside it. The intensity and energy spectrum of neutrons escaping the lunar surface are dependent on incident flux of Galactic Cosmic Rays (GCR) whose variability is associated with Solar Cycle and its peculiarities. We obtain first the share of neutrons entering through the field of view of collimator as a fraction of the total neutron flux by using the angular distribution of neutron exiting the Moon described by our Monte Carlo code. We computed next the count rate of the 3He sensor by using the neutron energy spectrum from McKinney et al. [JGR, 2006] and by consider geometry and gas pressure of the LEND sensor. Finally the neutron count rate obtained for the Apollo 17 epoch characterized by intermediate solar activity was adjusted to the LRO epoch characterized by low solar activity. It has been done by taking into account solar modulation potential, which affects the GCR flux, and in turn changes the neutron albedo flux.

  20. Oligocene-miocene mammalian fossils from Hongyazi Basin and its bearing on tectonics of Danghe Nanshan in northern Tibetan plateau.

    Science.gov (United States)

    Li, Qiang; Wang, Xiaoming; Xie, Guangpu; Yin, An

    2013-01-01

    A shortage of Cenozoic vertebrate fossils in the Tibetan Plateau has been an obstacle in our understanding of biological evolution in response to changes in tectonism, topography, and environment. This is especially true for Paleogene records, so far known by only two sites along the northern rim of the Plateau. We report a Hongyazi Basin in northern Tibetan Plateau that produces at least three mammalian faunas that span Oligocene through late Miocene. Located at the foothills of the Danghe Nanshan and presently connected to the northern margin of the Suganhu Basin through the Greater Haltang River, the intermountain basin is controlled by the tectonics of the Danghe Nanshan to the north and Chahan'ebotu Mountain to the south, making the basin sediments well suited for inferring the evolutionary history of these two mountain ranges. At the bottom of the local section, the Oligocene Haltang Fauna is best compared to the early Oligocene Desmatolagus-Karakoromys decessus assemblage in the Dingdanggou Fauna in Tabenbuluk Basin. The Middle Miocene Ebotu Fauna from the middle Hongyazi section shares many taxa with the late Middle Miocene Tunggur mammal assemblage in Inner Mongolia, such as Heterosminthus orientalis, Megacricetodon sinensis, Democricetodon lindsayi, and Alloptox gobiensis. Toward the top of the section, the Hongyazi Fauna includes late Miocene elements typical of Hipparion faunas of North China. All three faunas are of typical North China-Central Asian characteristics, suggesting a lack of geographic barriers for faunal differentiation through the late Miocene. Sedimentary packages producing these faunas are arrayed from north to south in progressively younger strata, consistent with a compressive regime to accommodate shortening between Danghe Nanshan and Chahan'ebotu Mountain by thrust faults and folds. With additional constraints from vertebrate fossils along the northern flanks of the Danghe Nanshan, an eastward propagation of the Danghe Nanshan is

  1. Oligocene-Miocene Mammalian Fossils from Hongyazi Basin and Its Bearing on Tectonics of Danghe Nanshan in Northern Tibetan Plateau

    Science.gov (United States)

    Li, Qiang; Wang, Xiaoming; Xie, Guangpu; Yin, An

    2013-01-01

    A shortage of Cenozoic vertebrate fossils in the Tibetan Plateau has been an obstacle in our understanding of biological evolution in response to changes in tectonism, topography, and environment. This is especially true for Paleogene records, so far known by only two sites along the northern rim of the Plateau. We report a Hongyazi Basin in northern Tibetan Plateau that produces at least three mammalian faunas that span Oligocene through late Miocene. Located at the foothills of the Danghe Nanshan and presently connected to the northern margin of the Suganhu Basin through the Greater Haltang River, the intermountain basin is controlled by the tectonics of the Danghe Nanshan to the north and Chahan’ebotu Mountain to the south, making the basin sediments well suited for inferring the evolutionary history of these two mountain ranges. At the bottom of the local section, the Oligocene Haltang Fauna is best compared to the early Oligocene Desmatolagus-Karakoromys decessus assemblage in the Dingdanggou Fauna in Tabenbuluk Basin. The Middle Miocene Ebotu Fauna from the middle Hongyazi section shares many taxa with the late Middle Miocene Tunggur mammal assemblage in Inner Mongolia, such as Heterosminthus orientalis, Megacricetodon sinensis, Democricetodon lindsayi, and Alloptox gobiensis. Toward the top of the section, the Hongyazi Fauna includes late Miocene elements typical of Hipparion faunas of North China. All three faunas are of typical North China-Central Asian characteristics, suggesting a lack of geographic barriers for faunal differentiation through the late Miocene. Sedimentary packages producing these faunas are arrayed from north to south in progressively younger strata, consistent with a compressive regime to accommodate shortening between Danghe Nanshan and Chahan’ebotu Mountain by thrust faults and folds. With additional constraints from vertebrate fossils along the northern flanks of the Danghe Nanshan, an eastward propagation of the Danghe Nanshan

  2. Tectonic evolution of the Sicilian Maghrebian Chain inferred from stratigraphic and petrographic evidences of Lower Cretaceous and Oligocene flysch

    Directory of Open Access Journals (Sweden)

    Puglisi Diego

    2014-08-01

    Full Text Available The occurrence of a Lower Cretaceous flysch group, cropping out from the Gibraltar Arc to the Balkans with a very similar structural setting and sedimentary provenance always linked to the dismantling of internal areas, suggests the existence of only one sedimentary basin (Alpine Tethys s.s., subdivided into many other minor oceanic areas. The Maghrebian Basin, mainly developed on thinned continental crust, was probably located in the westernmost sector of the Alpine Tethys. Cretaceous re-organization of the plates triggered one (or more tectonic phases, well recorded in almost all the sectors of the Alpine Tethys. However, the Maghrebian Basin seems to have been deformed by Late- or post-Cretaceous tectonics, connected with a “meso-Alpine” phase (pre-Oligocene, already hypothesized since the beginning of the nineties. Field geological evidence and recent biostratigraphic data also support this important meso- Alpine tectonic phase in the Sicilian segment of the Maghrebian Chain, indicated by the deformations of a Lower Cretaceous flysch sealed by Lower Oligocene turbidite deposits. This tectonic development is emphasized here because it was probably connected with the onset of rifting in the southern paleomargin of the European plate, the detaching of the so-called AlKaPeCa block (Auct.; i.e. Alboran + Kabylian + Calabria and Peloritani terranes and its fragmentation into several microplates. The subsequent early Oligocene drifting of these microplates led to the progressive closure of the Maghrebian Basin and the opening of new back-arc oceanic basins, strongly controlled by extensional processes, in the western Mediterranean (i.e. Gulf of Lion, Valencia Trough, Provençal Basin and Alboran Sea.

  3. Oligocene-miocene mammalian fossils from Hongyazi Basin and its bearing on tectonics of Danghe Nanshan in northern Tibetan plateau.

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    Qiang Li

    Full Text Available A shortage of Cenozoic vertebrate fossils in the Tibetan Plateau has been an obstacle in our understanding of biological evolution in response to changes in tectonism, topography, and environment. This is especially true for Paleogene records, so far known by only two sites along the northern rim of the Plateau. We report a Hongyazi Basin in northern Tibetan Plateau that produces at least three mammalian faunas that span Oligocene through late Miocene. Located at the foothills of the Danghe Nanshan and presently connected to the northern margin of the Suganhu Basin through the Greater Haltang River, the intermountain basin is controlled by the tectonics of the Danghe Nanshan to the north and Chahan'ebotu Mountain to the south, making the basin sediments well suited for inferring the evolutionary history of these two mountain ranges. At the bottom of the local section, the Oligocene Haltang Fauna is best compared to the early Oligocene Desmatolagus-Karakoromys decessus assemblage in the Dingdanggou Fauna in Tabenbuluk Basin. The Middle Miocene Ebotu Fauna from the middle Hongyazi section shares many taxa with the late Middle Miocene Tunggur mammal assemblage in Inner Mongolia, such as Heterosminthus orientalis, Megacricetodon sinensis, Democricetodon lindsayi, and Alloptox gobiensis. Toward the top of the section, the Hongyazi Fauna includes late Miocene elements typical of Hipparion faunas of North China. All three faunas are of typical North China-Central Asian characteristics, suggesting a lack of geographic barriers for faunal differentiation through the late Miocene. Sedimentary packages producing these faunas are arrayed from north to south in progressively younger strata, consistent with a compressive regime to accommodate shortening between Danghe Nanshan and Chahan'ebotu Mountain by thrust faults and folds. With additional constraints from vertebrate fossils along the northern flanks of the Danghe Nanshan, an eastward propagation of the

  4. Evidence for Late Oligocene-Early Miocene episode of transtension along San Andreas Fault system in central California

    Energy Technology Data Exchange (ETDEWEB)

    Stanley, R.G.

    1986-04-01

    The San Andreas is one of the most intensely studied fault systems in the world, but many aspects of its kinematic history remain controversial. For example, the period from the late Eocene to early Miocene is widely believed to have been a time of negligible strike-slip movement along the San Andreas fault proper, based on the rough similarity of offset of the Eocene Butano-Point of rocks Submarine Fan, the early Miocene Pinnacles-Neenach volcanic center, and an early Miocene shoreline in the northern Gabilan Range and San Emigdio Mountains. Nonetheless, evidence indicates that a late Oligocene-early Miocene episode of transtension, or strike-slip motion with a component of extension, occurred within the San Andreas fault system. The evidence includes: (1) about 22-24 Ma, widespread, synchronous volcanic activity occurred at about 12 volcanic centers along a 400-km long segment of the central California coast; (2) most of these volcanic centers are located along faults of the San Andreas system, including the San Andreas fault proper, the San Gregorio-Hosgri fault, and the Zayante-Vergeles fault, suggesting that these and other faults were active and served as conduits for magmas rising from below; (3) during the late Oligocene and early Miocene, a pull-apart basin developed adjacent to the San Andreas fault proper in the La Honda basin near Santa Cruz; and (4) during the late Oligocene and early Miocene, active faulting, rapid subsidence, and marine transgression occurred in the La Honda and other sedimentary basins in central California. The amount of right-lateral displacement along the San Andreas fault proper during this transtentional episode is unknown but was probably about 7.5-35 km, based on model studies of pull-apart basin formation. This small amount of movement is well within the range of error in published estimates of the offset of the Eocene to early Miocene geologic features noted.

  5. Timing of cut-and-fill sequences in the John Day Formation (Eocene-Oligocene), Painted Hills area, central Oregon

    Energy Technology Data Exchange (ETDEWEB)

    Bestland, E.A.; Retallack, G.J. (Univ. of Oregon, Eugene, OR (United States). Dept. of Geological Sciences); Swisher, C.C. III (Inst. of Human Origins, Berkeley, CA (United States)); Fremd, T.J. (John Day Fossil Beds National Monument, John Day, OR (United States))

    1993-04-01

    Large-scale cut-and-fill features in the Eocene-Oligocene part of the John Day Formation in the Pained Hills area of central Oregon can be interpreted as terrestrial depositional sequences, mapped as lithostratigraphic units, and correlated to North American Land Mammal Ages (NALMA). New laser-fusion 40Ar/39Ar single-crystal ages from the John Day Formation provide evidence for the timing of these sequences and a revised placement of the Eocene-Oligocene boundary. The sequences are bound by erosional surfaces that have relief of up to 60 m, are marked in places by claystone breccias full of reworked soil clasts, and separate otherwise conformable strata. The lowermost depositional sequence in the John Day Formation contains very well developed, Fe- and Al-rich paleosols, laterite horizons, and the welded tuff of member A (39.7 my), and probably correlates to the Duchesean and Chadronian NALMA. These brick-rid claystones are sharply truncated by prominent detrital laterite horizon. Overlying this basal sequence is a second sequence of much less well developed paleosols, abundant tuffs and lacustrine tuffaceous claystones. This sequence contains a distinctive biotite tuff (33 my) and the type locality of the Bridge Creek fossil flora and probably correlates to the Orellan NALMA. Above this biotite tuff are alternating red, dark gray, and tan paleosols and a prominent crystal vitric tuff (32.7 my). The Eocene-Oligocene boundary lies between these two sequences, associated with the laterite horizon that truncates the basal red beds. A major truncation surface cuts this sequence and is overlain by a third sequence of thin red paleosols which probably correlates with the Whitneyan NALMA. Above this is a fourth sequence (Arikareean NALMA) consisting of greenish-tan paleosols, a crystal vitric tuff near its base (29.8 my) and the Picture Gorge Ignimbrite (28.7 my).

  6. Extensional Basins in a Convergent Margin: Oligocene-Early Miocene Salar de Atacama and Calama basins, Central Andes

    Science.gov (United States)

    Jordan, T. E.; Mpodozis, C.; Blanco, N.; Pananont, P.; Dávila, F.

    2004-12-01

    The Salar de Atacama Basin (SdAB) is the largest and most persistent sedimentary basin of northern Chile, accumulating nonmarine sediment from Cretaceous to modern times. Its northwestern neighbor, the Calama, was a Cenozoic basin. Although SdAB was in the backarc zone early in the Andean orogeny, both are now forearc basins. Others demonstrated that the basins overlie anomalously cold, strong, and dense crust and lithosphere. We focus on an extensional Oligocene basin stage. Interpretation of the basin-controlling faults is based on seismic reflection studies supported by field relations. The SdAB is limited to the west by the NNE-trending, steeply east-dipping, Paciencia Fault (PF). The PF experienced 5-7 km of down-to-the-east offset during the Oligocene-early Miocene. Syntectonic strata, an arid succession of siliciclastics and evaporites, are asymmetric, with thicknesses of 5000 m and abundant halite adjacent to the PF, and of 1000 m with fine detrital clastic strata 25 km farther east. Relations in conglomeratic growth strata that overlap the PF also demonstrate normal displacement during sediment accumulation. Seismic data reveal that a buried normal fault with 1-1.5 km down-to-the-east displacement limits the western margin of the Oligocene-Miocene Calama siliciclastic basin fill. Regionally, Oligocene-early Miocene margin-parallel strike-slip deformation dominated northwest of the basins, contributing sinistral offset (West Fissure Fault) to the northern segment of the long-lived Domeyko Fault System. The new SdAB and Calama data reveal that a 20,000 km2 domain of extensional basins existed within the dominantly strike-slip region. Even if PF and the fault in the Calama Basin were transtensional, the proportion of extension to strike-slip displacement is much greater in these basins than elsewhere in northern Chile. Further study is required to understand what combination of factors caused this kinematic distinction as well as delayed the onset of CVZ

  7. Variability of the planktonic foraminifera community across the Eocene/Oligocene boundary, Fuente Caldera Section, Baetic Ranges (Spain)

    Science.gov (United States)

    Legarda-Lisarri, A.

    2013-12-01

    During the Eocene/Oligocene transition, in a massive extinction event that took place about 33.7 million years ago, the current high resolution study analyzes qualitatively and quantitatively the community structure of the planktonic foraminifera that were preserved in the hemipelagic sediments of the Tethys Sea. The sampled section of the Fuente Caldera column, located in the Baetic mountain ranges, spans a register of 396,551.7 years. Based in the identification of 27 species, that belong to 13 genera and 2 families of foraminifera, there have been found three biozones of Gonzalvo Zonation (Gonzalvo, 2002) in the studied stratigraphic interval: Turborotalia cocoaensis and Cribrohantkenina lazzarii Biozones (Rupelian), and Paragloborotalia increbescens (Priabonian). The planktonic foraminifera associations variability patterns are defined by paleoecologic indexes (diversity index, high and low latitude species index and planktonic and benthic foraminifera index), by geochemical proxies: δ18O and δ13C and by 'Q' Mode Factor Analysis. They prove that the deposition environment is outer platform and also, they suggest that the studied area in the Tethys Sea underwent many thermal pulses, during which some species extinct or appear. In the first extinction event the species Turborotalia cocoaensis and Turborotalia cunialensis became extinct. In the second one, Hantkenina alabamensis, Hantkenina brevispina, Cribrohantkenina lazzarii and Pseudohastigerina micra became extinct while a succession occured; Globigerina officinalis, Globoturborotalita anguliofficinalis and Tenuitellinata angustiumbilicata appeared. The cooling event that finished in the Lower Oligocene was the biggest of these pulses, which was extremely abrupt and corresponds to the Oi-1 event that was described by Miller (Miller, 1991). All this evidences that the planktonic foraminifera extinction in the Upper Eocene was a gradual and fast event, what is supported by the Factor Analysis application. Key

  8. Oligocene and Miocene arc volcanism in northeastern California: evidence for post-Eocene segmentation of the subducting Farallon plate

    Science.gov (United States)

    Colgan, J.P.; Egger, A.E.; John, D.A.; Cousens, B.; Fleck, R.J.; Henry, C.D.

    2011-01-01

    The Warner Range in northeastern California exposes a section of Tertiary rocks over 3 km thick, offering a unique opportunity to study the long-term history of Cascade arc volcanism in an area otherwise covered by younger volcanic rocks. The oldest locally sourced volcanic rocks in the Warner Range are Oligocene (28–24 Ma) and include a sequence of basalt and basaltic andesite lava flows overlain by hornblende and pyroxene andesite pyroclastic flows and minor lava flows. Both sequences vary in thickness (0–2 km) along strike and are inferred to be the erosional remnants of one or more large, partly overlapping composite volcanoes. No volcanic rocks were erupted in the Warner Range between ca. 24 and 16 Ma, although minor distally sourced silicic tuffs were deposited during this time. Arc volcanism resumed ca. 16 Ma with eruption of basalt and basaltic andesite lavas sourced from eruptive centers 5–10 km south of the relict Oligocene centers. Post–16 Ma arc volcanism continued until ca. 8 Ma, forming numerous eroded but well-preserved shield volcanoes to the south of the Warner Range. Oligocene to Late Miocene volcanic rocks in and around the Warner Range are calc-alkaline basalts to andesites (48%–61% SiO2) that display negative Ti, Nb, and Ta anomalies in trace element spider diagrams, consistent with an arc setting. Middle Miocene lavas in the Warner Range are distinctly different in age, composition, and eruptive style from the nearby Steens Basalt, with which they were previously correlated. Middle to Late Miocene shield volcanoes south of the Warner Range consist of homogeneous basaltic andesites (53%–57% SiO2) that are compositionally similar to Oligocene rocks in the Warner Range. They are distinctly different from younger (Late Miocene to Pliocene) high-Al, low-K olivine tholeiites, which are more mafic (46%–49% SiO2), did not build large edifices, and are thought to be related to backarc extension. The Warner Range is ∼100 km east of the

  9. Glaciation and erosion of Eastern Greenland at the Eocene-Oligocene transition: Insights from low-temperature thermochronology

    Science.gov (United States)

    Bernard, Thomas; Steer, Philippe; Gallagher, Kerry; Szulc, Adam; Whittam, Andrew

    2016-04-01

    Climate cooling through the Late Cenozoic was important in the evolution of glaciated mountain ranges. While the onset of accelerated Cenozoic exhumation is generally associated with the Quaternary at mid-latitudes, coincident with the local onset of glaciation, some high-latitude passive margins may have experienced earlier glaciation starting at 30-38 Ma or even 45 Ma. To address this issue, we use a set of new AFT data from 16 sub-vertical profiles sampled along the fjords of the central Eastern Greenland margin between 68° and 76° N, combined with new apatite (U-Th-Sm)/He (AHe) data from selected profiles. To infer thermal histories and exhumation from these profiles, we use the software QTQt. The modeling results show a major phase of exhumation in the East Greenland margin between 68° and 76° N starting at 30±5 Ma. The spatial distribution of the exhumation shows that normal faulting on East Greenland margin had no resolvable influence on exhumation related to the cooling phase. However, the timing is coincident with the dramatic worldwide fall of surface temperature at the Eocene-Oligocene transition. We therefore suggest that a transition from an Eocene fluvial to an Oligocene glacial-dominated landscape triggered a period of enhanced erosion. We infer from the thermal histories that around 2.7±1.9 km of erosion occurred close to the coast since the Eocene-Oligocene transition. This amount of erosion is consistent with the incision of the fjords and with the effective removal of 2.3±1.5 km of basalt thickness, deduced by the thermal modeling of a heating phase at 55±5 Ma. This phase of erosion is most strongly evidenced near the coast, suggesting either that continental ice extent was limited to the coastal areas or that erosion was less efficient outside these areas, leading to no obvious signal in thermochronometric data further north. Overall, this study provides the first onshore evidence of the onset of continental ice in East Greenland margin

  10. Early Oligocene plant diversity along the Upper Rhine Graben: The fossil flora of Rauenberg, Germany

    Directory of Open Access Journals (Sweden)

    Kovar-Eder Johanna

    2016-12-01

    Full Text Available The macroflora of Rauenberg, Baden-Württemberg, Germany, is treated monographically. The plant-bearing sediments are marine, mainly well-bedded clay- to siltstones, the so-called Fischschiefer, which are part of the Bodenheim Formation. Based on nannoplankton they are dated to nannoplankton zone NP 23 (Rupelian, Lower Oligocene. The plant remains, mainly leaves and some fructifications, are preserved as compressions. The taxonomic assignment is based on gross morphology and cuticle characteristics. The flora yields marine algae and remains of the very diverse terrestrial flora. A total of 68 taxa, including three types of algae, one cycad, 12 conifers, and 49 dicots, among them 5 palms, are described. The following fossil species are described for the first time: Laurophyllum rauenbergense, Myrica obliquifolia, Distylium metzleri, ? Berchemia altorhenana, ? Ternstroemites maritiae, Trachelospermum kelleri, Oleinites altorhenana, O. rauenbergensis, Dicotylophyllum badense, D. oechsleri, D. vesiculaeferens, D. ziegleri, ? Viscophyllum hendriksiae, and Cladites vesiculaeferens. Dicotylophyllum vesiculaeferens and Cladites vesiculaeferens bear peculiar, complex cuticular structures presumably representing salt-secreting glands. Both taxa are interpreted to derive from one plant species of yet uncertain systematic affinity. The flora bears a high proportion of broad-leaved, presumably evergreen taxa, whereas the diversity of modern Arcto-Tertiary taxa (sensu Kvaček 1994 is rather low. Most abundant are Platanus neptuni, Daphnogene cinnamomifolia, and Tetraclinis salicornioides. On the family level, Lauraceae (10 species and Pinaceae (8 are most diverse, followed by Arecaceae (4-5, Cupressaceae, and Myricaceae (4 species each. Surprisingly, Fagaceae are documented solely by a single leaf of Eotrigonobalanus furcinervis f. haselbachensis, and the record of Pentaphyllaceae remains ambiguous (? Ternstroemites maritiae. Sloanea olmediaefolia is recorded

  11. Abrupt Terrestrial Cooling at the Eocene-Oligocene Transition in the Southern Hemisphere

    Science.gov (United States)

    Auerbach, D. J.; Hren, M. T.; Pacini, A.

    2016-12-01

    The Eocene-Oligocene transition (EOT) from a greenhouse to icehouse climate state is the most significant climate transition of the Cenozoic (Zachos et al., 2001). The EOT marks the first presence of large-scale ice in the Cenozoic, with ice sheets appearing on Antarctica. The expression of the EOT in temperature and water isotopes has been documented widely in the marine realm (Coxall et al., 2005; Ivany et al., 2003; Lear et al., 2008; Liu et al., 2009; Pagani et al., 2005; Zachos et al., 2001), as well as in the terrestrial realm (Hren et al., 2013; Sheldon, 2009; Zanazzi et al., 2007). With such dramatic climatic changes occurring in Antarctica, it would be reasonable to expect neighboring Patagonia to hold excellent records of this transition. However, existing terrestrial records from Patagonia show negligible change in the water isotope record (Kohn et al., 2015; Kohn et al., 2010). Analyses of the δD of volcanic glass from the Vera Member of the Sarmiento Formation in the well-dated (Dunn et al., 2013; Ré et al., 2010) sedimentary section at Gran Barranca allow us to reconstruct the water isotope record in central Patagonia during the EOT. These data show a drop in precipitation δD of 20‰ over 100-200 kyr followed by a recovery of 15‰ over the next 0.5-1.0 Myr. Based on observed δ-T relationships (Dansgaard, 1964; Kohn et al., 2004), this excursion implies a cooling of 6°C during the EOT. This magnitude of cooling, as well as the pattern of rapid temperature change followed by a more gradual recovery matches well with nearby marine records of temperature (Liu et al., 2009) and water isotopes (Muza et al., 1983) from DSDP site 511. Other data from Gran Barranca show suppression of wildfire (Selkin et al., 2015) and possible increases in canopy openness (Dunn et al., 2015), which may be driven by this cooling, but it appears that vegetation populations (Strömberg et al., 2013) and evolution of grazing mammals (Kohn et al., 2015) were negligibly

  12. Magnetic Field - Vertical Component of the Total Field Intensity for the Epoch 2010.0 - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This map layer shows lines of equal vertical intensity of the Earth's magnetic field, derived from the International Geomagnetic Reference Field (IGRF) for the epoch...

  13. Changes in the depth habitat of the Oligocene planktic foraminifera (Dentoglobigerina venezuelana) induced by thermocline deepening in the eastern equatorial Pacific

    Science.gov (United States)

    Matsui, Hiroki; Nishi, Hiroshi; Takashima, Reishi; Kuroyanagi, Azumi; Ikehara, Minoru; Takayanagi, Hideko; Iryu, Yasufumi

    2016-06-01

    Understanding planktic foraminiferal depth habitat along with consistent taxonomic concepts is key to accurate reconstruction of paleoceanographic records. The Oligocene-Pliocene long-ranging and widely distributed species Dentoglobigerina venezuelana lived in the mixed layer (shallower) during the early Oligocene, whereas the same species calcified at thermocline or subthermocline depths (deeper) during the late Oligocene and Miocene. The exact timing of the species' depth habitat change and its possible relationships with Oligocene climate dynamics remain unknown. Here we reveal isotopic records of D. venezuelana along with the Paragloborotalia siakensis group (a mixed-layer dweller) by using sediments at Integrated Ocean Drilling Program Site U1334 in the eastern equatorial Pacific throughout the Oligocene. A two-step depth habitat change of D. venezuelana is apparent: (1) from upper to lower mixed layer (~27.4 Ma) and (2) from lower mixed layer to thermocline depth (~26.3 Ma). In addition, the planktic foraminiferal faunal assemblage experienced a marked change from dominantly thermocline (deeper) species to abundant mixed-layer (shallower) species, suggesting that depth habitat shifts of D. venezuelana were clearly related to thermocline deepening in the eastern equatorial Pacific. Comparison of the first isotopic shift (~27.4 Ma) at multiple sites (U1334, U1333, and 1218) revealed a southward depth habitat change of D. venezuelana within ~200 kyr, implying overall thermocline deepening with reduced steepness in the eastern equatorial Pacific. We consider that global warming conditions during the late Oligocene likely caused thermocline deepening with upwelling decrease in the eastern equatorial Pacific, guiding D. venezuelana to adapt to greater depths in the water column.

  14. A new sediment-dwelling pholadid bivalve from Oligocene glaciomarine sediments of King George Island, West Antarctica

    Directory of Open Access Journals (Sweden)

    Krzysztof Hryniewicz

    2016-12-01

    Full Text Available We present a re-description of the pholadid bivalve from the Oligocene Polonez Cove Formation, King George Island, West Antarctica, previously identified as Penitella sp. The study is based on a collection of 210 specimens, preserved exclusively in life position in flask-shaped Gastrochaenolites type borings which have been subsequently buried by glaciomarine diamictite. The systematic study showed that this pholadid is a new species belonging to the genus Pholadidea rather than to Penitella and we name it Pholadidea gradzinskii sp. nov. The species is one of very few Late Cretaceous–Paleogene pholadids that we could safely identify as Pholadidea. All of them are known exclusively from the southern Pacific and adjacent areas (New Zealand, Antarctica, and Patagonia. We demonstrate that the genus attained its Recent broad distribution before the middle Miocene, when the first species of Pholadidea appeared in the Northern Hemisphere. The mass occurrence of P. gradzinskii in the Oligocene of West Antarctica results from favourable living condition in a shallow marine environment. Low sedimentation rate allowed the settlement of numerous larvae and their subsequent metamorphosis, growth, and maturity terminated by the mass mortality caused by the burial by marine diamictite. The sediment-boring Paleogene species of Pholadidea, among them P. gradzinskii, follow the wood-boring Late Cretaceous species P. (Hatasia wiffenae, which reflects a general pattern of evolution of substrate selection among pholadoid bivalves.

  15. Evolution of an Eocene-Oligocene Saline Lake Depositional System and Its Controlling Factors, Jianghan Basin, China

    Institute of Scientific and Technical Information of China (English)

    Chunju Huang; Linda Hinnov

    2014-01-01

    The Upper Eocene–Lower Oligocene Qianjiang Formation of the Jianghan Basin in central China consists of a 4 700-m-thick lacustrine succession, containing 1 800 m of halite deposits. The maximum thickness of the formation is 4 700 m, and includes 1 800 m of halite. We have identi-fied eight third-order depositional sequences based on pinch-out and onlap stratigraphic patterns in 2-D and 3-D seismic data and well logs. The basin evolved from a deep to shallow under-filled lake during the Eocene–Oligocene interval. The main rock types are dark mudstones, halite, and siltstone/sandstone in the depocenter, and alternating mudstone and gypsum in shallower areas. The vertical succession indicates a strong sedimentary cyclicity. Depositional facies indicate the presence of two lake system types. Halite developed in a saline lake system, whereas clastic sediments were deposited in freshwater lake systems. The alternating sediment types indicate that the basin cycled repeatedly between saline and freshwater lake systems. This cyclicity was caused by availability of accommodation space that was controlled by a combination of climate change, tectonic subsidence and sediment supply; notably, the highest frequency cycles occurred at Milankovitch timescales con-trolled by the Earth’s orbital variations. The cyclic halite plays an important role in generating and preserving oil in the Qianjiang Formation of the Qianjiang depression.

  16. Threshold in North Atlantic-Arctic circulation controlled by the Oligocene-Miocene subsidence of the Greenland-Scotland Ridge.

    Science.gov (United States)

    Stärz, Michael; Jokat, Wilfried; Knorr, Gregor; Lohmann, Gerrit

    2016-04-01

    Changes in high latitude ocean gateways are thought to be main drivers of Cenozoic climate evolution. However, the link between global climate changes and the early ocean gateway formation between the North Atlantic and the Arctic Ocean (incl. the Greenland and Norwegian Seas) controlled by the subsidence of the Greenland-Scotland Ridge is poorly understood. Here, we use a coupled ocean-atmosphere general circulation model for Oligocene-Miocene boundary conditions to address a threshold behaviour for the ventilation of the Arctic Ocean controlled by the subsidence of the Greenland-Scotland Ridge. Our model simulations reveal that a deepening of the ridge from approx. 100 to 200 metres below sea-level forces major reorganizations in the North Atlantic-Arctic circulation associated with extreme salinity and temperature changes in the Arctic Ocean. These changes are induced by an abrupt regime shift from restricted estuarine conditions to a bi-directional flow regime similar to today. Taking uncertainties in timing into account this suggests that tectonic processes, which started at the late Eocene to Oligocene controlled the climate and circulation regime of the Arctic Ocean.

  17. The Oligocene carbonate platform of the Zagros Basin, SW Iran: An assessment of highly-complex geological heritage

    Science.gov (United States)

    Habibi, Tahereh; Ruban, Dmitry A.

    2017-05-01

    North Africa and the Middle East possess rich geological heritage, but the latter is yet to be fully identified and described. The Oligocene carbonate platform of the Zagros Basin in southwest Iran, which corresponds to the lower part of the Asmari Formation, has significant potential for geoconservation and geotourism. The types of the geological heritage, their value, and the possible geosites have been assessed. The studied deposits are interesting because of lithology (carbonate rocks), fossils (larger foraminifera, other microfossils, diverse marine invertebrates, fish microremains, and trace fossils), biostratigraphical developments, facies (homoclinal carbonate ramp) and signature of global events (glacioeustatic fluctuations), and outstanding hydrocarbon resources. The five main geological heritage types are sedimentary, palaeontological, stratigraphical, palaeogeographical, and economical, from which the palaeontological, palaeogeographical, and economical types are of global rank. The Khollar and Kavar sections in the Fars Province of Iran are recommended as geosites suitable for research, education, and tourism. The high complexity of the geological heritage linked to the Oligocene carbonate platform of the Zagros Basin implies the phenomenon of geodiversity should be understood with regard to the relationships between types and their values.

  18. Diversification of rhacophorid frogs provides evidence for accelerated faunal exchange between India and Eurasia during the Oligocene

    Science.gov (United States)

    Li, Jia-Tang; Li, Yang; Klaus, Sebastian; Rao, Ding-Qi; Hillis, David M.; Zhang, Ya-Ping

    2013-01-01

    The accretion of the Indian subcontinent to Eurasia triggered a massive faunal and floral exchange, with Gondwanan taxa entering into Asia and vice versa. The traditional view on the Indian–Asian collision assumes contact of the continental plates during the Early Eocene. Many biogeographic studies rely on this assumption. However, the exact mode and timing of this geological event is still under debate. Here we address, based on an extensive phylogenetic analysis of rhacophorid tree frogs, if there was already a Paleogene biogeographic link between Southeast Asia and India; in which direction faunal exchange occurred between India and Eurasia within the Rhacophoridae; and if the timing of the faunal exchange correlates with one of the recently suggested geological models. Rhacophorid tree frogs showed an early dispersal from India to Asia between 46 and 57 Ma, as reconstructed from the fossil record. During the Middle Eocene, however, faunal exchange ceased, followed by increase of rhacophorid dispersal events between Asia and the Indian subcontinent during the Oligocene that continued until the Middle Miocene. This corroborates recent geological models that argue for a much later final collision between the continental plates. We predict that the Oligocene faunal exchange between the Indian subcontinent and Asia, as shown here for rhacophorid frogs, also applies for other nonvolant organisms with an Indian–Asian distribution, and suggest that previous studies that deal with this faunal interchange should be carefully reinvestigated. PMID:23401521

  19. Reproductive structures of Rhamnaceae from the Cerro del Pueblo (Late Cretaceous, Coahuila) and Coatzingo (Oligocene, Puebla) Formations, Mexico.

    Science.gov (United States)

    Calvillo-Canadell, Laura; Cevallos-Ferriz, Sergio R S

    2007-10-01

    Recently discovered fossil flowers from the Cretaceous Cerro del Pueblo and flowers and fruits from the Oligocene Coatzingo Formations are assigned to the Rhamnaceae. The Cretaceous flower, Coahuilanthus belindae Calvillo-Canadell and Cevallos-Ferriz, gen. et sp. nov., is actinomorphic with fused perianth parts forming a slightly campanulate to cupulate floral cup, with sepals slightly keeled and spatulate clawed petals. The Oligocene fossils include Nahinda axamilpensis Calvillo-Canadell and Cevallos-Ferriz, gen. et sp. nov. (characterized by its campanulate bisexual flower with stamens opposite, adnate to and enfolded by petals; and with the ovary ripening into a drupe), and a winged fruit assigned to Ventilago engoto Calvillo-Canadell and Cevallos-Ferriz, sp. nov. The flowers and drupe features indicate closer affinity to Zizipheae and/or Rhamneae, while the single samaroid fruit suggests the presence of Ventilagineae. However, the unique character combination in the fossil flowers precludes placing them in extant genera. Nevertheless, the history of the family is long and can be traced back to the Campanian. A detailed phylogenetic revision of the group that uses morphological characters from both extant and fossil plants is needed to better understand the significance of these records as well as other important fossils of the family.

  20. Palynology of the Rupelian to Burdigalian (Oligocene to Lower Miocene) interval of the Alma-1X well, Danish North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Schioeler, P.

    2003-07-01

    A palynological study of cuttings samples from the North Sea well Alma-1X documents for the first time the dinoflagellae cyst and acritarch assemblage in the Oligocene to Lower Miocene interval of the Central North Sea. The interval is characterised by a poor foraminifera assemblage yielding a relatively low stratigraphic resolution, whereas the palynomorph assemblage is rich. Two hundred and three microplankton taxa were encountered in the study interval. The distribution of dinoflagellates and acritarchs in the well suggests a subdivision of the Oligocene to Lower Miocene interval into 24 zones based on first downhole occurrence of key taxa. The subdivsion lends support from unpublished consultancy report data from several other wells in the Danish North Sea. However, as the the subdivion builds on published data from one well only, it is considered informal until more documentatin is at hand. Four new species and on e new subspecies are described from the study interval: Amphorosphaeridium almae Schioeler sp. nov., Dalella rota Schioeler sp. nov., Filisphaera pachyderma Schioeler sp. nov., Pentadinium corium Schioeler sp. nov. and Spiniferites pseudofurcatus verrucosus Schioeler ssp., nov. Pseudospiniferites manumii Lund, 2002 is emended and transferred to the genus Spiniferites. (au)

  1. Acrostichum, a Pioneering Fern of Floodplain Areas from the Late Oligocene Sariñena Formation of the Iberian Peninsula

    Science.gov (United States)

    Ferrer, Javier; Diez, José B.

    2016-01-01

    Acrostichum is considered today an opportunistic fern in disturbed areas, which indicates the first stages of colonisation of such zones. However, in the fossil record, Acrostichum appears related to fluvio-lacustrine environments, freshwater marshes and mangrove deposits. We report here for first time fossil evidence of Acrostichum that reveals a pioneering behaviour of this fern in the colonisation of perturbed communities in Europe, which corroborates previous assumptions about the paleobiology of Acrostichum. Plant remains were collected from the Chattian (late Oligocene) La Val fossil site (Estadilla, Huesca, northeastern Spain) belonging to the Sariñena Formation, which mainly embraces crevasse splays, levees and floodplain deposits. Evidence shows that Acrostichum grew within the levee’s vegetal community or close to/on the river banks as well as on floodplain areas and closer to/on the shores of ephemeral ponds. But most importantly, the observed co-existence of Equisetum and Acrostichum remains in the same beds indicates that such strata represent short-lived inundated terrains, e.g., floodplains where the water table was temporarily stagnant. Evidence shows wetland environments dominated by pioneering taxa, implying a pioneering role for Acrostichum during the late Oligocene in the Iberian Peninsula. PMID:27631099

  2. Paleobiogeography of scleractinian reef corals: Changing patterns during the Oligocene-Miocene climatic transition in the Mediterranean

    Science.gov (United States)

    Perrin, Christine; Bosellini, Francesca R.

    2012-02-01

    During the Oligocene-Miocene Greenhouse-to-Icehouse climatic transition, the biogeography of reef corals or zooxanthellate-like scleractinian corals was gradually changing from a pan-tropical Tethyan Province in the Eocene to three reef-coral Provinces of the Western Atlantic-Caribbean, Indo-Pacific and Mediterranean. Our REEFCORAL database encompasses updated and homogenized data on paleoenvironmental and systematics of scleractinian corals occurring in the Oligocene and Miocene outcrops from circum-Mediterranean regions, provided by most of relatively recently published data in the literature and by the study of published and unpublished collections of coral specimens from the same area, including the important collections housed at the MNHN (Paris) and our own collections. As there is no validated direct criterion for the identification of the coral-zooxanthellate symbiosis in the fossil record, and considering the difficulty to use the biogeochemical approaches in the context of this study, the subjectivity of the morphological criteria and the relative recent age of the fossil corals we are dealing with, a uniformitarian approach has been used for inferring the symbiotic status of scleractinian genera in REEFCORAL. Among the 158 genera included in our database, 93 can be considered as zooxanthellate and 10 have a doubtful zooxanthellate status. This relatively exhaustive database was used to reconstruct the temporal and spatial distribution of scleractinian corals in the Mediterranean during the Oligocene-Miocene time in order to discuss the interplaying effects of the global cooling at that time, the re-organization of the Tethyan realm resulting from the African, Arabian and Eurasian plate collision and the emergence of the Alpine chains, driving the gradual northward movement of the whole region outside the tropical/subtropical belt. It is shown that the structure of the Mediterranean z-coral Oligocene-Miocene paleobiodiversity was characterized by many

  3. Tectono-sedimentary constraints to the Oligocene-to-Miocene evolution of the Peloritani thrust belt (NE Sicily)

    Science.gov (United States)

    Giunta, G.; Nigro, F.

    1999-12-01

    The Peloritani thrust belt belongs to the southern sector of the Calabrian Arc and is formed by a set of south-verging tectonic units, including crystalline basement and sedimentary cover (from the top: Aspromonte U.; Mela U.; Mandanici U.; Fondachelli U.; Longi-Taormina U.), piled up starting from Late Oligocene. At least two main terrigenous clastic formations lie with complicated relationships on top of the previous units: the Frazzanò Fm (Oligocene) and the Stilo-Capo d'Orlando Fm (Late Oligocene?-Early Miocene), as syn-to-post-tectonic deposits. These clastic deposits have different characteristics, in space and time, representing or flysch-like sequences involved in several thrust events (Frazzanò Fm) or molassic-like sequences (Stilo-Capo d'Orlando Fm), which unconformably overlie the tectonic units. In the present paper we describe a kinematic model of the progressive foreland migration of the Peloritani thrust belt, starting from Oligocene, carrying piggy-back basins and incorporating foredeep deposits, recognised in the Frazzanò-Stilo-Capo d'Orlando terrigenous successions. In general, the facies and structural observations on the overall Oligo-Miocene clastic sequences, outcropping in the Western Peloritani Mts, indicate: (a) the distal character of the Frazzanò Fm; (b) a complex group of terrigenous facies of the Stilo-Capo d'Orlando Fm, with lateral-to-vertical organisation, characterised by a distal-to-proximal-to-distal facies trend; (c) facies analogies of the basal portions of the Stilo-Capo d'Orlando Fm with the Frazzanò Fm; (d) the involvement of the Frazzanò Fm in lowermost and more external thrusting, and of the basal (Late Oligocene?) distal Stilo-Capo d'Orlando facies in the higher and inner thrusting during the early stages of deformation; (e) the involvement of the proximal Stilo-Capo d'Orlando facies in the tectonic edifice during the Early Miocene deformation; (f) the generally unconformable stratigraphical contacts of the higher

  4. A New GNSS Single-Epoch Ambiguity Resolution Method Based on Triple-Frequency Signals

    Directory of Open Access Journals (Sweden)

    Shengli Wang

    2017-02-01

    Full Text Available Fast and reliable ambiguity resolution (AR has been a continuing challenge for real-time precise positioning based on dual-frequency Global Navigation Satellite Systems (GNSS carrier phase observation. New GNSS systems (i.e., GPS modernization, BDS (BeiDou Navigation Satellite System, GLONASS (Global Navigation Satellite System, and Galileo will provide multiple-frequency signals. The GNSS multiple-constellation and multiple-frequency signals are expected to bring great benefits to AR. A new GNSS single-epoch AR method for a short-range baseline based on triple-frequency signals is developed in this study. Different from most GNSS multiple-constellation AR methods, this technique takes advantage of the triple-frequency signals and robust estimation as much as possible. In this technique, the double difference (DD AR of the triple-frequency observations is achieved in the first step. Second, the triple-frequency carrier phase observations with fixed ambiguities are used with the dual-frequency carrier phase observations to estimate their ambiguity. Finally, to realize reliable GNSS single-epoch AR, robust estimation is involved. The performance of the new technique is examined using 24 hours of GPS/GLONASS/BDS observation collected from a short-range baseline. The results show that single-epoch AR of the GNSS signals can be realized using this new technique. Moreover, the AR of BDS Geostationary Earth Orbit (GEO satellites’ observations is easier than are those of the Medium Earth Orbit (MEO and Inclined Geosynchronous Satellite Orbit (IGSO satellites’ observations.

  5. Primordial non-Gaussianity from the 21 cm power spectrum during the epoch of reionization.

    Science.gov (United States)

    Joudaki, Shahab; Doré, Olivier; Ferramacho, Luis; Kaplinghat, Manoj; Santos, Mario G

    2011-09-23

    Primordial non-Gaussianity is a crucial test of inflationary cosmology. We consider the impact of non-Gaussianity on the ionization power spectrum from 21 cm emission at the epoch of reionization. We focus on the power spectrum on large scales at redshifts of 7 to 8 and explore the expected constraint on the local non-Gaussianity parameter f(NL) for current and next-generation 21 cm experiments. We show that experiments such as SKA and MWA could measure f(NL) values of order 10. This can be improved by an order of magnitude with a fast-Fourier transform telescope like Omniscope.

  6. Will nonlinear peculiar velocity and inhomogeneous reionization spoil 21 cm cosmology from the epoch of reionization?

    Science.gov (United States)

    Shapiro, Paul R; Mao, Yi; Iliev, Ilian T; Mellema, Garrelt; Datta, Kanan K; Ahn, Kyungjin; Koda, Jun

    2013-04-12

    The 21 cm background from the epoch of reionization is a promising cosmological probe: line-of-sight velocity fluctuations distort redshift, so brightness fluctuations in Fourier space depend upon angle, which linear theory shows can separate cosmological from astrophysical information. Nonlinear fluctuations in ionization, density, and velocity change this, however. The validity and accuracy of the separation scheme are tested here for the first time, by detailed reionization simulations. The scheme works reasonably well early in reionization (≲40% ionized), but not late (≳80% ionized).

  7. Primordial Non-Gaussianity from the 21 cm Power Spectrum during the Epoch of Reionization

    OpenAIRE

    Joudaki, Shahab; Dore, Olivier; Ferramacho, Luis; Kaplinghat, Manoj; Santos, Mario G.

    2011-01-01

    Primordial non-Gaussianity is a crucial test of inflationary cosmology. We consider the impact of non-Gaussianity on the ionization power spectrum from 21 cm emission during the epoch of reionization. We focus on the power spectrum on large scales at redshifts of 7 to 8 and explore the expected constraint on the local non-Gaussianity parameter f_NL for current and next-generation 21 cm experiments. We show that experiments such as SKA and MWA could measure f_NL values of order 10. This can be...

  8. Chebotarev A.P. – "the Grey Cardinal" of Cossack Reforms of the Epoch of Liberation?

    Directory of Open Access Journals (Sweden)

    Alexey A. Volvenko

    2015-06-01

    Full Text Available The article deals with the major milestones of life and career of Chebotarev A.P. – Don Cossack General, the deputy chief of the irregular troops of the War Ministry in the 60s of XIX century. The research focus is made on trying to prove that Chebotarev was an important figure (named "grey cardinal" in the program planning of Cossack reforms in preparation the concrete projects on the Don transformations in the epoch of the liberation of Alexander II.

  9. Statistical Properties of Multi-epoch Spectral Variability of SDSS Stripe82 Quasars

    CERN Document Server

    Kokubo, Mitsuru; Minezaki, Takeo; Doi, Mamoru; Kawaguchi, Toshihiro; Sameshima, Hiroaki; Koshida, Shintaro

    2014-01-01

    We investigate the UV-optical (longward of Ly$\\alpha$ 1216\\AA) spectral variability of nearly 9000 quasars ($0epoch photometric data within the SDSS Stripe 82 region. The regression slope in the flux-flux space of a quasar light curve directly measures the color of the flux difference spectrum, then the spectral shape of the flux difference spectra can be derived by taking a careful look at the redshift dependence of the regression slopes. First, we confirm that the observed quasar spectrum becomes bluer when the quasar becomes brighter. We infer the spectral index of the composite difference spectrum as $\\alpha_{\

  10. Density fluctuations from the quark-hadron epoch and primordial nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, G.M.; Mathews, G.J.; Alcock, C.R.

    1987-12-01

    We present a simple thermodynamic model of the quark-hadron transition in the early universe and use this model to estimate how the size of isothermal baryon number fluctuations which emerge from this epoch depend on the temperature of the transition and other uncertain quantities of the underlying QCD physics. We calculate primordial nucleosynthesis in the presence of these fluctuations and find that ..cap omega.. = 1 in baryons is possible only if the measured abundances of /sup 7/Li and /sup 2/H reflect substantial destruction during the evolution of the galaxy. 29 refs., 7 figs.

  11. Quantifying the Imprecision of Accretion Theory and Implications for Multi-Epoch Observations of Protoplanetary Discs

    DEFF Research Database (Denmark)

    Blackman, Eric G.; Nauman, Farrukh; Edgar, Richard G.

    2010-01-01

    If accretion disc emission results from turbulent dissipation, then axisymmetric accretion theory must be used as a mean field theory: turbulent flows are at most axisymmetric only when suitably averaged. Spectral predictions therefore have an intrinsic imprecision that must be quantified...... that at which the dominant eddy turnover time ($\\sim$ orbit time) exceeds the time interval between observations; the epochs would then be sampling the same member of the stochastic ensemble. We discuss the application of these principles to protoplanetary discs for which there is presently a paucity of multi...

  12. Joint US/UK Epoch World Magnetic Model 1995. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, J.M.; Coleman, R.J.; Shiel, D.L.

    1995-04-01

    This report contains a detailed summary of the data used, analyses performed, modeling techniques employed, and results obtained during the course of the 1995 Epoch World Magnetic Modeling effort. This report also contains the GEOMAG algorithm and describes its uses and limitations. Charts derived from the WMM-95 model and the GEOMAG algorithm for both the main geomagnetic field components and their secular variations are presented on Mercator and polar stereographic projections. Additionally, the numerical values of the main geomagnetic field components and their secular variations are tabulated on a 5-degree worldwide grid.

  13. Radio-loud and radio-quiet quasars: one population, different epochs of observation

    CERN Document Server

    Blundell, Katherine

    2008-01-01

    I bring together evidence for the rapidity with which quasars' radio synchrotron lobe emission fades and for the intermittency with which jet plasma is ejected from individual quasars and radio galaxies and affirm the picture presented by Nipoti et al (2005) that the radio-loudness of quasars is a function of the epoch at which they are observed. I briefly illustrate this account with examples of successive episodes of jet activity where the axis along which jet plasma is launched appears to have precessed. A new model for the weak core radio emission from radio-quiet quasars, that is not any kind of jet ejecta, is also briefly described.

  14. A northwest Atlantic environmental magnetic perspective on the Oligocene - Miocene Transition

    Science.gov (United States)

    van Peer, Tim; Xuan, Chuang; Lippert, Peter; Wilson, Paul; Liebrand, Diederik

    2016-04-01

    The Oligocene - Miocene Transition (OMT) is characterised by a long-term carbon isotope shift and a transient +1‰ oxygen-isotope excursion, the 'Mi1-event'. The Mi1-event has been attributed to transient global cooling and ice sheet expansion on Antarctica, but the boreal component of this major climatic event is poorly understood. The nannofossil oozes recovered at Site U1406 during IODP (Integrated Ocean Drilling Program) Expedition 342 (Paleogene Newfoundland Sediment Drifts) provide an unprecedented opportunity to study the Mi1-event, as these contourite drifts were deposited at 2-6 cm/kyr and are ideally located at the Newfoundland Ridge (northwest Atlantic) below the Deep Western Boundary Current (DWBC). To better understand the combined effects of global cooling, ice sheet formation and global circulation, we generated an environmental magnetic record to study the origin, transportation, deposition and possible diagenesis of magnetic minerals. We carried out continuous high-resolution (1-cm intervals) palaeomagnetic and environmental magnetic analyses across the OMT and present the first continuous environmental magnetic record across Mi1 from a Northern Hemisphere perspective. The geomagnetic polarity stratigraphy interpreted from shore-based u-channel measurements clearly reveals the three C6Cn subchrons spanning the duration of the Mi1-event, and provide a first-order age model for the studied sediment sequence at Site U1406. Rock magnetic experiments conducted at low (down to 20K) and high (up to 700°C) temperatures for selected bulk sediment and magnetic extract samples show the Verwey transition at ~120K, and magnetic components with blocking temperatures at ~250°C and ~580°C. Analysis of isothermal remanent magnetisation (IRM) acquisition curves also indicates the existence of two magnetic components with mean coercivity of ~50 mT and ~400 mT. These observations are consistent with the presence of a fine-grained stoichiometric magnetite component

  15. Petrology of Oligocene Ghaleh Yaghmesh granitoids in the west of Yazd province

    Directory of Open Access Journals (Sweden)

    Bahareh Fazeli

    2017-02-01

    Full Text Available Introduction The generation and evolution of granitic magmas has been a hot debated subject among petrologists. The diversity of their origin has led different authors to propose that these rocks are not simple in their origin and might be generated in more ways than one. In the past several decades, many petrologists used a variety characteristics to subdivide the granitoid rocks. Such proposals have of course been forward by Chappell and White (1974 for the granitoids of Eastern Australia. They divided these granitoids into two distinct types (I-and S-type granitic rocks, which they interpreted as being derived from igneous and sedimentary source rocks, respectively. The Ghaleh Yaghmesh plutonic massif is located in the most western part of Yazd and it forms a part of the Urumieh-Dokhtar magmatic belt. The belt is response to subduction of Neo-Tethyan oceanic crust beneath central Iran (Alavi, 1994. During Cretaceous-Late Tertiary, numerous granitoid bodies were exposed in this belt, many of which have been studied by a number of workers (e.g. Sepahi and Malvandi, 2008; Honarmand et al., 2013; Kananian et al., 2014. The massif composed of diorite, quartzdiorite, tonalite, granodiorite and granite (Oligocene intruded into the Eocene volcanic and pyroclastic rocks including rhyolite, rhyodacite, andesitic, rhyodacitic and rhyolitic tuff. The main purpose of the present paper is to describe the petrography, and whole rock geochemistry of the Ghaleh Yaghmish granitoids as well as discussing their petrogenetic and tectonic significance in the light of the regional geological framework of the study area. Materials and methods After field studies and sampling, fifty thin sections were prepared for petrographic study. Twenty-one fresh samples were selected for XRF chemical analysis performed at the Southern Methodist University (Dallas - USA. Thin polished sections of granodiorite rocks were prepared for composition determining and structure formula

  16. The Intricate Role of Cold Gas and Dust in Galaxy Evolution at Early Cosmic Epochs

    Science.gov (United States)

    Riechers, Dominik Alexander; Capak, Peter; Carilli, Christopher; Walter, Fabian

    2015-08-01

    Cold molecular and atomic gas plays a central role in our understanding of early galaxy formation and evolution. It represents the material that stars form out of, and its mass, distribution, excitation, and dynamics provide crucial insight into the physical processes that support the ongoing star formation and stellar mass buildup. We will discuss the most recent progress in studies of gas-rich galaxies out to the highest redshifts through detailed investigations with the most powerful facilities across the electromagnetic spectrum, with a particular focus on new observations obtained with the Karl G. Jansky Very Large Array (VLA) and the Atacama Large (sub-) Millimeter Array (ALMA). These studies cover a broad range in galaxy properties, and provide a detailed comparison of the physical conditions in massive, dust-obscured starburst galaxies and star-forming active galactic nuclei hosts within the first billion years of cosmic time. Facilitating the impressive sensitivity of ALMA, this investigation also includes the first direct, systematic study of the star-forming interstellar medium, gas dynamics, and dust obscuration in (much less luminous and massive) "typical" galaxies at such early epochs. These new results show that "typical" z>5 galaxies are significantly metal-enriched, but not heavily dust-obscured, consistent with a decreasing contribution of dust-obscured star formation to the star formation history of the universe towards the earliest cosmic epochs.

  17. Measuring the Epoch of Reionization using [CII] Intensity Mapping with TIME-Pilot

    Science.gov (United States)

    Crites, Abigail; Bock, James; Bradford, Matt; Bumble, Bruce; Chang, Tzu-Ching; Cheng, Yun-Ting; Cooray, Asantha R.; Hailey-Dunsheath, Steve; Hunacek, Jonathon; Li, Chao-Te; O'Brient, Roger; Shirokoff, Erik; Staniszewski, Zachary; Shiu, Corwin; Uzgil, Bade; Zemcov, Michael B.; Sun, Guochao

    2017-01-01

    TIME-Pilot (the Tomographic Ionized carbon Intensity Mapping Experiment) is a new instrument designed to probe the epoch of reionization (EoR) by measuring the 158 um ionized carbon emission line [CII] from redshift 5 - 9. TIME-Pilot will also probe the molecular gas content of the universe during the epoch spanning the peak of star formation (z ~ 1 -3) by making an intensity mapping measurement of the CO transitions in the TIME-Pilot band (CO(3-2), CO(4-3), CO(5-4), and CO(6-5)). I will describe the instrument we are building which is an R of ~100 spectrometer sensitive to the 200-300 GHz radiation. The camera is designed to measure the line emission from galaxies using an intensity mapping technique. This instrument will allow us to detect the [CII] clustering fluctuations from faint galaxies during EoR and compare these measurements to predicted [CII] amplitudes from current models. The CO measurements will allow us to constrain models for galaxies at lower redshift. The [CII] intensity mapping measurements that will be made with TIME-Pilot and detailed measurements made with future more sensitive mm-wavelength spectrometers are complimentary to 21-cm measurements of the EoR and complimentary to direct detections of high redshift galaxies with HST, ALMA, and, in the future, JWST.

  18. Contamination of the Epoch of Reionization power spectrum in the presence of foregrounds

    Science.gov (United States)

    Sims, Peter H.; Lentati, Lindley; Alexander, Paul; Carilli, Chris L.

    2016-11-01

    We construct foreground simulations comprising spatially correlated extragalactic and diffuse Galactic emission components and calculate the `intrinsic' (instrument-free) two-dimensional spatial power spectrum and the cylindrically and spherically averaged three-dimensional k-space power spectra of the Epoch of Reionization (EoR) and our foreground simulations using a Bayesian power spectral estimation framework. This leads us to identify a model-dependent region of optimal signal estimation for our foreground and EoR models, within which the spatial power in the EoR signal relative to the foregrounds is maximized. We identify a target field-dependent region, in k-space, of intrinsic foreground power spectral contamination at low k⊥ and k∥ and a transition to a relatively foreground-free intrinsic EoR window in the complement to this region. The contaminated region of k-space demonstrates that simultaneous estimation of the EoR and foregrounds is important for obtaining statistically robust estimates of the EoR power spectrum; biased results will be obtained from methodologies that ignore their covariance. Using simulated observations with frequency-dependent uv-coverage and primary beam, with the former derived for the Hydrogen Epoch of Reionization Array in 37-antenna and 331-antenna configuration, we recover instrumental power spectra consistent with their intrinsic counterparts. We discuss the implications of these results for optimal strategies for unbiased estimation of the EoR power spectrum.

  19. Tracing the reionization epoch with ALMA: [CII] emission in z~7 galaxies

    CERN Document Server

    Pentericci, L; Castellano, M; Fontana, A; Maiolino, R; Guaita, L; Vanzella, E; Grazian, A; Santini, P; Yan, H; Cristiani, S; Conselice, C; Giavalisco, M; Hathi, N; Koekemoer, A

    2016-01-01

    We present new results on [CII]158$\\mu$ m emission from four galaxies in the reionization epoch. These galaxies were previously confirmed to be at redshifts between 6.6 and 7.15 from the presence of the Ly$\\alpha$ emission line in their spectra. The Ly$\\alpha$ emission line is redshifted by 100-200 km/s compared to the systemic redshift given by the [CII] line. These velocity offsets are smaller than what is observed in z~3 Lyman break galaxies with similar UV luminosities and emission line properties. Smaller velocity shifts reduce the visibility of Ly$\\alpha$ and hence somewhat alleviate the need for a very neutral IGM at z~7 to explain the drop in the fraction of Ly$\\alpha$ emitters observed at this epoch. The galaxies show [CII] emission with L[CII]=0.6-1.6 x10$^8 L_\\odot$: these luminosities place them consistently below the SFR-L[CII] relation observed for low redshift star forming and metal poor galaxies and also below z =5.5 Lyman break galaxies with similar star formation rates. We argue that previou...

  20. Interferometric Monitoring of Gamma-ray Bright AGNs I: Results of Single-epoch Multifrequency Observations

    CERN Document Server

    Lee, Sang-Sung; Algaba, Juan-Carlos; Zhao, Guang-Yao; Hodgson, Jeffrey A; Kim, Dae-Won; Park, Jongho; Kim, Jae-Young; Miyazaki, Atsushi; Byun, Do-Young; Kang, Sincheol; Kim, Jeong-Sook; Kim, Soon-Wook; Kino, Motoki; Trippe, Sascha

    2016-01-01

    We present results of single-epoch very long baseline interferometry (VLBI) observations of gamma-ray bright active galactic nuclei (AGNs) using the Korean VLBI Network (KVN) at 22, 43, 86, and 129~GHz bands, which are part of a KVN key science program, Interferometric Monitoring of Gamma-ray Bright AGNs (iMOGABA). We selected a total of 34 radio-loud AGNs of which 30 sources are gamma-ray bright AGNs with flux densities of $>6\\times10^{-10}$~ph~cm$^{-2}$~s$^{-1}$. Single-epoch multi-frequency VLBI observations of the target sources were conducted during a 24-hr session on 2013 November 19 and 20. All observed sources were detected and imaged at all frequency bands with or without a frequency phase transfer technique which enabled the imaging of 12 faint sources at 129~GHz, except for one source. Many of the target sources are resolved on milliarcsecond scales, yielding a core-jet structure with the VLBI core dominating the synchrotron emission on the milliarcsecond scale. CLEAN flux densities of the target s...

  1. A fast pulse phase estimation method for X-ray pulsar signals based on epoch folding

    Institute of Scientific and Technical Information of China (English)

    Xue Mengfan; Li Xiaoping; Sun Haifeng; Fang Haiyan

    2016-01-01

    X-ray pulsar-based navigation (XPNAV) is an attractive method for autonomous deep-space navigation in the future. The pulse phase estimation is a key task in XPNAV and its accuracy directly determines the navigation accuracy. State-of-the-art pulse phase estimation techniques either suffer from poor estimation accuracy, or involve the maximization of generally non-convex object function, thus resulting in a large computational cost. In this paper, a fast pulse phase estimation method based on epoch folding is presented. The statistical properties of the observed profile obtained through epoch folding are developed. Based on this, we recognize the joint prob-ability distribution of the observed profile as the likelihood function and utilize a fast Fourier transform-based procedure to estimate the pulse phase. Computational complexity of the proposed estimator is analyzed as well. Experimental results show that the proposed estimator significantly outperforms the currently used cross-correlation (CC) and nonlinear least squares (NLS) estima-tors, while significantly reduces the computational complexity compared with NLS and maximum likelihood (ML) estimators.

  2. A fast pulse phase estimation method for X-ray pulsar signals based on epoch folding

    Directory of Open Access Journals (Sweden)

    Xue Mengfan

    2016-06-01

    Full Text Available X-ray pulsar-based navigation (XPNAV is an attractive method for autonomous deep-space navigation in the future. The pulse phase estimation is a key task in XPNAV and its accuracy directly determines the navigation accuracy. State-of-the-art pulse phase estimation techniques either suffer from poor estimation accuracy, or involve the maximization of generally non-convex object function, thus resulting in a large computational cost. In this paper, a fast pulse phase estimation method based on epoch folding is presented. The statistical properties of the observed profile obtained through epoch folding are developed. Based on this, we recognize the joint probability distribution of the observed profile as the likelihood function and utilize a fast Fourier transform-based procedure to estimate the pulse phase. Computational complexity of the proposed estimator is analyzed as well. Experimental results show that the proposed estimator significantly outperforms the currently used cross-correlation (CC and nonlinear least squares (NLS estimators, while significantly reduces the computational complexity compared with NLS and maximum likelihood (ML estimators.

  3. Calculation of the shangyuan jinian elapsed-year-since--grand-epoch of the kaixi calendar

    Science.gov (United States)

    Wang, Y. X.

    2007-01-01

    Gauss C.F. (1777-1855) pointed out in his Disquisitiones Arithmeticae (1801) that linear congruences came from the problems of calendars: ``This usage arose in the problem of chronology when we seek to determine what Julian year it is whose indiction, golden number, and solar cycle are given.'' The Problem of Zhili Yanji (Design for a Calendar by Means of the Sexagenary Cycle) in Qin Jiushao's Shushu Jiuzhang ( Mathematical Treatise in Nine Sections ) (A.D. 1247) recorded the design development of the Kaixi Calendar (1207-1251) which was the unique existent material recorded during this period of more than 1000 years when the algorithm of Shangyuan Jinian Elapsed-Year-since--Grand-Epoch used by ancient and medieval Chinese calendarists until A.D. 1280. It is devoted to restituting the full calculation of this data by analysising original thought on concept about linear congruences for the conditions of the Grand-Epoch, the cycle consonant principle, the concept of the Qiyuan Solar-period, the reason for the Ruyuansui Entry-of-Solar-period, the Dayan method and the counting process for the Yuansu Number-of-Solar-period.

  4. OPENING THE 21 cm EPOCH OF REIONIZATION WINDOW: MEASUREMENTS OF FOREGROUND ISOLATION WITH PAPER

    Energy Technology Data Exchange (ETDEWEB)

    Pober, Jonathan C.; Parsons, Aaron R.; Ali, Zaki [Astronomy Department, U. California, Berkeley, CA (United States); Aguirre, James E.; Moore, David F. [Department of Physics and Astronomy, U. Pennsylvania, Philadelphia, PA (United States); Bradley, Richard F. [Department of Electrical and Computer Engineering, U. Virginia, Charlottesville, VA (United States); Carilli, Chris L. [National Radio Astronomy Observatory, Socorro, NM (United States); DeBoer, Dave; Dexter, Matthew; MacMahon, Dave [Radio Astronomy Laboratory, U. California, Berkeley, CA (United States); Gugliucci, Nicole E. [Department of Astronomy, U. Virginia, Charlottesville, VA (United States); Jacobs, Daniel C. [School of Earth and Space Exploration, Arizona State U., Tempe, AZ (United States); Klima, Patricia J. [National Radio Astronomy Observatory, Charlottesville, VA (United States); Manley, Jason; Walbrugh, William P. [Square Kilometer Array, South Africa Project, Cape Town (South Africa); Stefan, Irina I. [Cavendish Laboratory, Cambridge (United Kingdom)

    2013-05-10

    We present new observations with the Precision Array for Probing the Epoch of Reionization with the aim of measuring the properties of foreground emission for 21 cm epoch of reionization (EoR) experiments at 150 MHz. We focus on the footprint of the foregrounds in cosmological Fourier space to understand which modes of the 21 cm power spectrum will most likely be compromised by foreground emission. These observations confirm predictions that foregrounds can be isolated to a {sup w}edge{sup -}like region of two-dimensional (k , k{sub Parallel-To })-space, creating a window for cosmological studies at higher k{sub Parallel-To} values. We also find that the emission extends past the nominal edge of this wedge due to spectral structure in the foregrounds, with this feature most prominent on the shortest baselines. Finally, we filter the data to retain only this ''unsmooth'' emission and image its specific k{sub Parallel-To} modes. The resultant images show an excess of power at the lowest modes, but no emission can be clearly localized to any one region of the sky. This image is highly suggestive that the most problematic foregrounds for 21 cm EoR studies will not be easily identifiable bright sources, but rather an aggregate of fainter emission.

  5. Multi-Epoch Observations of Extremely High-Velocity Emergent Broad Absorption

    CERN Document Server

    Rogerson, Jesse A; Hidalgo, Paola Rodríguez; Pirkola, Patrik; Brandt, William N; Ak, Nur Filiz

    2015-01-01

    We present the discovery of the highest velocity CIV broad absorption line to date in the z=2.47 quasar SDSS J023011.28+005913.6, hereafter J0230. In comparing the public DR7 and DR9 spectra of J0230, we discovered an emerging broad absorption trough outflowing at~60,000 km/s. In pursuing follow up observations we discovered a second emergent broad absorption trough outflowing at ~40,000 km/s. We collected seven spectral epochs of J0230 that demonstrate emergent and rapidly (~10 days in the rest-frame) varying broad absorption. We investigate two possible scenarios that could cause these rapid changes: bulk motion and ionization variability. Given our multi-epoch data, a transverse motion scenario would likely be a flow-tube feature travelling across the emitting region at 8,000 =1540 cm^-3 and is at r_{eq} >= 1.37 kpc, or is at r < 1.37 kpc with no constraint on the density.

  6. Schubert and Beethoven - Adorno’s early antipods of the music in bougeois epoch

    Directory of Open Access Journals (Sweden)

    Jeremić-Molnar Dragana

    2012-01-01

    Full Text Available In this article the authors are reconstructing the dichotomies which the young Theodor Adorno was trying to detect in the music of the bourgeois epoch and personify in two antipodes - Franz Schubert and Ludwig van Beethoven. Although already a devotee of Arnold Schönberg and the 20th century music avantgardism, Adorno was, in his works prior to his exile from Germany (1934, intensively dealing with Schubert and his opposition towards Beethoven. While Beethoven was a bold and progressive revolutionary, fascinated by the “practical reason” and the mission to rise up and reach the stars, Schubert wanted none of it (almost anticipating the failure of the whole revolutionary project. Instead, he was looking backwards, to primordial nature and the possibility of man to participate in its mythic cycles of death and regeneration. The lack of synthesis between this two opposing tendencies in the music of early bourgeois epoch lead to the “negative dialectics” of Schönberg and 20th century music avantgardism and to the final separation of Beethovenian musical progress and Schubertian musical mimesis. [Projekat Ministarstva nauke Republike Srbije, br. 177019: Identiteti srpske muzike u svetskom kulturnom kontekstu, i br. 179035: Izazovi nove društvene integracije u Srbiji - koncepti i akteri

  7. Early Oligocene geomagnetic field behavior from ODP Site 1128: Complex records of short-period polarity events

    Science.gov (United States)

    Molina-Garza, R. S.; Fuller, M. D.

    2001-12-01

    At Site 1128, in the Great Australian Bight, Leg 182 of the Ocean Drilling Program recovered a thick (~350 m) section of Upper Eocene and Lower Oligocene marine calcareous clays. Shipboard measurements established a magnetostratigraphy that can unambiguously be correlated to chrons C13n to C10n of the global polarity time scale (GPTS), and a less complete record of chrons C17n to C15r (due to poor core recovery). Correlation to the GPTS is further supported by available biostratigraphic data. For the Lower Oligocene sequence, average sedimentation rate is estimated at ~4 cm/kyr. The sediments recovered thus allow to test for the completeness and reliability of the geomagnetic field polarity during the Early Oligocene. The original shipboard long-core measurements suggested the presence of additional short polarity events or geomagnetic field excursions during chrons C13n, C12r, C11r, and C11n. In order to examine the reliability of the record and the nature of possible short-polarity events, we obtained discrete samples from the entire sequence at ~1 m intervals, with a closer sample spacing in critical intervals (~10 cm). The natural remanence of these sediments is normally simple. After removing a small soft overprint, the magnetization decays towards the origin with distributed coercivities and distributed unblocking temperatures. Demagnetization behavior and other rock magnetic data indicate that the remanence resides primarily in a cubic phase such as magnetite or maghemite, with a small contribution from hematite. Discrete samples from chron C12r did not reproduce the long-core record for two of the supposed events, single samples suggest the presence of short events or cryptochrons near the base of both C13n and C12r, and multiple samples suggest the existence of short-period normal polarity events during C11r and near the top of C12r. The records of these events are, however, complex. Demagnetization results indicate that the magnetization consists of an

  8. Petrography and geochemistry of Oligocene bituminous coal from the Jiu Valley, Petrosani basin (southern Carpathian Mountains), Romania

    Energy Technology Data Exchange (ETDEWEB)

    Belkin, Harvey E.; Tewalt, Susan J. [U.S. Geological Survey, 956 National Center, Reston, VA 20192 (United States); Hower, James C. [University of Kentucky Center for Applied Energy Research, 2540 Research Park Drive, Lexington, KY 40511 (United States); Stucker, J.D. [University of Kentucky Center for Applied Energy Research, 2540 Research Park Drive, Lexington, KY 40511 (United States); University of Kentucky Department of Earth and Environmental Sciences, Lexington, KY 40506 (United States); O' Keefe, Jennifer M.K. [Morehead State University, Morehead, KY, 40351 (United States); Tatu, Calin A. [University of Medicine and Pharmacy, Department of Immunology, Clinical Laboratory No. 1, Pta. E. Murgu No. 2, RO-1900 Timisoara (Romania); Buia, Grigore [University of Petrosani, Department of Geology, University St. 20, RO-2675 Petrosani (Romania)

    2010-05-01

    Belt samples of Oligocene (Chattian) bituminous coal from 10 underground mines located in the Jiu Valley, Hunedoara County, Petrosani basin, Romania, have been examined and analyzed for proximate and ultimate analysis, major-, minor- and trace-element chemistry, organic petrography, and vitrinite reflectance. The mineral chemistry and mode of occurrence of trace elements also have been investigated using SEM and electron microprobe techniques. Twenty coal beds occur in the Jiu Valley and most of the samples are from bed no. 3, the most productive bed of the Dilja-Uricani Formation of Oligocene age. The Petrosani basin, oriented SW-NE, is 48-km long, 10-km wide at the eastern part and 2-km wide at the western part. The coal mines are distributed along the center of the valley generally following the Jiu de Vest River. Reflectance measurements indicate that the rank of the coals ranges from high-volatile B to high-volatile A bituminous. Overall, rank decreases from the southwest to the northeast. In bed no. 3, R{sub max} varies from 0.75% in the northeast to 0.93% in the southwest. Although, most Oligocene coals in Romania and adjacent countries are lignite in rank, the Jiu Valley bituminous coals have been affected by regional metamorphism and attending hydrothermal fluids related to the Alpine orogenic event. The coals are all dominated by vitrinite; resinite and funginite are important minor macerals in most of the coals. Pyrite and carbonate generally dominate the mineral assemblages with carbonate more abundant in the northwest. Siderite occurs as nodules and masses within the macerals (generally vitrinite). Dolomite and calcite occur as fracture fillings, plant-cell fillings, and in other authigenic forms. Late-stage fracture fillings are siderite, dolomite, calcite, and ankerite. In one instance, two populations of siderite ({proportional_to} 35 and {proportional_to} 45 wt.% FeO) plus ankerite fill a large fracture. Late-stage pyrite framboid alteration is Ni

  9. Paleoecology and biostratigraphic data of the large benthic foraminifera in the Oligocene-Miocene Qom Formation in Kahak area, in the Urumieh-Dokhtar province in Iran

    Directory of Open Access Journals (Sweden)

    mahnaz amirshahkarami

    2016-08-01

    Full Text Available The Oligocene-Miocene Qom Formation was deposited in different thickness in the Central Iran, Urumiehh–Dokhtar magmatic arc and Sanandaj–Sirjan provinces in Iran. The Oligocene-Miocene Kahak section of the Qom Formation in the Urumiehh–Dokhtar magmatic arc has been studied, in order to biostratigraphic data of the large benthic foraminifera. In the Kahak section, the foraminifera assemblages of the Qom Formation consist of Nummulites fichteli, Nummulites vascus, Eulepidina dilitata, Nephrolepidina sp., Neprolepidina tournoueri, Eulepidina sp., Pseudolituonella reicheli, Miogypsina sp., Miogypsina irregularis, Amphistegina sp., Operculina sp., Bozorginella qumiensis, Triloculina trigonula, Triloculina tricarinata, Peneroplis sp., Peneroplis thomasi, Dendritina ranji, Triloculina trigonula, Rotalia sp., Pyrgo sp., Elphidium sp., Borelis melo and Borelis curdica.  In the Kahak section of the Qom Formation, four assemblage biozones of the large benthic foraminifera have been recognized from Rupelian, Chattian, Aquitanian and Burdigalian stages. These biozones are similar to assemblage biozones of the Oligocene-Miocene Asmari Formation in the Zagros Basin in southwest of Iran. Distribution type of the Oligocene-Miocene foraminifera in the Kahak depositions of the Qom Formation indicates to depositional settings of the  lagoon, open lagoon and shallow open marine paleoenvironments. There is some similarity of foraminifera assemblage in Qom Formation sediments with other locality of Tethys including Mediterranean and Indo-West Pacific.

  10. A partial braincase and other skeletal remains of Oligocene angel sharks (Chondrichthyes, Squatiniformes) from northwest Belgium, with comments on squatinoid taxonomy

    NARCIS (Netherlands)

    Mollen, F.H.; Bakel , van B.W.M.; Jagt, J.W.M.

    2016-01-01

    A detailed redescription of a chondrocranium from the basal Boom Clay Formation (Rupelian, Upper Oligocene) at the SVK clay pit, Sint-Niklaas (province of Oost-Vlaanderen, Belgium), previously assigned to the sawshark Pristiophorus rupeliensis, is presented. The chondrocranium is re-identified as th

  11. A partial braincase and other skeletal remains of Oligocene angel sharks (Chondrichthyes, Squatiniformes) from northwest Belgium, with comments on squatinoid taxonomy

    NARCIS (Netherlands)

    Mollen, F.H.; Bakel , van B.W.M.; Jagt, J.W.M.

    A detailed redescription of a chondrocranium from the basal Boom Clay Formation (Rupelian, Upper Oligocene) at the SVK clay pit, Sint-Niklaas (province of Oost-Vlaanderen, Belgium), previously assigned to the sawshark Pristiophorus rupeliensis, is presented. The chondrocranium is re-identified as th

  12. A partial braincase and other skeletal remains of Oligocene angel sharks (Chondrichthyes, Squatiniformes) from northwest Belgium, with comments on squatinoid taxonomy

    NARCIS (Netherlands)

    Mollen, F.H.; Bakel , van B.W.M.; Jagt, J.W.M.

    2016-01-01

    A detailed redescription of a chondrocranium from the basal Boom Clay Formation (Rupelian, Upper Oligocene) at the SVK clay pit, Sint-Niklaas (province of Oost-Vlaanderen, Belgium), previously assigned to the sawshark Pristiophorus rupeliensis, is presented. The chondrocranium is re-identified as

  13. Global change across the Oligocene-Miocene transition : High-resolution stable isotope records from IODP Site U1334 (equatorial Pacific Ocean)

    NARCIS (Netherlands)

    Beddow, Helen M.; Liebrand, Diederik; Sluijs, Appy; Wade, Bridget S.; Lourens, Lucas J.

    2016-01-01

    The Oligocene-Miocene transition (OMT) (∼23 Ma) is interpreted as a transient global cooling event, associated with a large-scale Antarctic ice sheet expansion. Here we present a 2.23 Myr long high-resolution (∼3 kyr) benthic foraminiferal oxygen and carbon isotope (δ18O and δ13C) record from

  14. Environmental- and sea-level change revealed by dinoflagellate cysts during the Eocene-Oligocene transition at St. Stephens Quarry, Alabama, USA

    NARCIS (Netherlands)

    Quaijtaal, W.; Wade, B.S.; Schouten, S.; Houben, A.J.P.; Rosenthal, Y.; Miller, K.G.; Brinkhuis, H.

    2011-01-01

    The Eocene-Oligocene transition (EOT, ~34 Myr ago) represents the final transition from the early Paleogene “Greenhouse” into the present “Icehouse” by the initiation of Antarctic glaciation. The EOT is recorded in deep-sea benthic foraminiferal oxygen isotope (δ18O) records as two increasing steps,

  15. Global change across the Oligocene-Miocene transition : High-resolution stable isotope records from IODP Site U1334 (equatorial Pacific Ocean)

    NARCIS (Netherlands)

    Beddow, Helen M.; Liebrand, Diederik; Sluijs, Appy; Wade, Bridget S.; Lourens, Lucas J.

    2016-01-01

    The Oligocene-Miocene transition (OMT) (∼23 Ma) is interpreted as a transient global cooling event, associated with a large-scale Antarctic ice sheet expansion. Here we present a 2.23 Myr long high-resolution (∼3 kyr) benthic foraminiferal oxygen and carbon isotope (δ18O and δ13C) record from Integr

  16. Hydrologic budget of the late Oligocene Lake Creede and the evolution of the upper Rio Grande drainage system

    Science.gov (United States)

    Barton, Paul B.; Steven, Thomas A.; Hayba, Daniel O.

    2000-01-01

    The filling history, hydrologic budget, and geomorphic development of ancient Lake Creede and its tributary basin are evaluated to determine the factors that controlled its character. The lake filled the Creede caldera that formed in the late Oligocene as a consequence of the eruption of the Snowshoe Mountain Tuff. The caldera's sedimentary fill accumlated to a depth of about 1.26 km and had a volume of about 89 km3. The highest lake level was ~3300 m (10,800 ft) present altitude before it drained eastward across a broad volcanic plateau as the ancestral Rio Grande. A tributary canyon several hundred meters deep was cut into hard rhyolite in the north wall of the caldera before the lake was more than half full; its presence demonstrates that ancient Lake Creede filled slowly and thus occupied a long-lived, closed basin. The slow filling rate is incompatible with the present water flux through the Creede caldera basin, because such a flow would fill the basin geologically instantaneously. This mismatch, together with the recognition that the Oligocene climate was similar to that of today, forces the reexamination of the hydrologic and geomorphic history of the caldera. That appraisal shows that the caldera cannot have resurged rapidly immediately after caldera collapse, and that ancient watershed must have been lass than half as large as the present upper Rio Grande basin. The ancient lake had a more or less constant surface area of about 200 km2 that approximated a steady-state condition between inflow and evaporation. Although the lake level fluctuated with climatic variations, its surface elevation steadily climbed as sediment accumulated, accelerating as resurgance and dome growth usurped spacewithin the basin. It could have had one playa stage early in its development and another after the basin had nearly filled with sediment, but there is no direct evidence for either. At least the lower half of the sedimentary column (the part sampled by the scientific

  17. New remains of the enigmatic cetartiodactyl Bugtitherium grandincisivum Pilgrim, 1908, from the upper Oligocene of the Bugti Hills (Balochistan, Pakistan)

    Science.gov (United States)

    Métais, Grégoire; Antoine, Pierre-Olivier; Baqri, Syed Rafiqul Hassan; Benammi, Mouloud; Crochet, Jean-Yves; de Franceschi, Dario; Marivaux, Laurent; Welcomme, Jean-Loup

    2006-07-01

    Newly discovered fossil material of the enigmatic cetartiodactyl Bugtitherium grandincisivum from the upper Oligocene of the Bugti Member of the Chitarwata Formation in the Bugti Hills (Balochistan, Pakistan) is reported. These new specimens consist of two fragmentary muzzles (one preserving the first incisors and belonging to a juvenile) and a fragmentary right mandible with m3. The morphologies of the anterior dentition and m3 provided by these new specimens confirm the validity of the genus Bugtitherium and advocate probable anthracotheriid affinity for the genus rather than entelodontid or suoid affinities, but do not definitively close the debate about Bugtitherium’s familial affinities within Cetartiodactyla. Although still poorly documented, this large-sized anthracotheriid-like cetartiodactyl is a possible key form for understanding the early evolution of hippos, and, in turn, the ancestry of whales, because of both its morphological similarities with hippos and primitive Paleogene whales and its Tethysian distribution.

  18. Late Oligocene calcareous nannofossils from Albanian-Thessalian intramontane basin (Bozdovec Section, Albania – a quantitative approach

    Directory of Open Access Journals (Sweden)

    Mădălina-Elena Kallanxhi

    2016-04-01

    Full Text Available Quantitative and semi-quantitative analyses of calcareous nannofossils were performed on samples collected from Bozdovec Section (Albanian-Thessalian intramontane basin, Albania. The calcareous nannofossil assemblages are dominated by: small reticulofenestrids, Cycligargolithus floridanus, Coccolithus pelagicus, Sphenolithus spp., Reticulofenestra scrippsae, Helicosphaera spp., Clausicoccus spp., Reticulofenestra bisecta, Cycligargolithus abisectus. Biostratigraphically, the studied outcrop is assigned to the Late Oligocene NP25 - Sphenolithus ciperoensis Zone. In the Mediterranean area, this interval can be correlated with the MNP25a - Sphenolithus ciperoensis Zone, while according to the zonation for low to middle latitudes the investigated material would belong to the CNO5 - Sphenolithus ciperoensis TZ. High amounts of small reticulofenestrids and sphenoliths point to warm well stratified paleoenvironment.

  19. Reasons for the outbreak of microphytoplankton productivity in the late Oligocene Turtas Lake-Sea, Western Siberia

    Science.gov (United States)

    Kuzmina, O. B.; Kuzmin, D. V.; Shurygin, B. N.

    2017-06-01

    Palynological (dinocysts) and geochemical data were compared for the first time for Paleogene sediments of borehole no. 8 (settlement of Russkaya Polyana, Omsk oblast). The layers with a concentrated amount of dinocysts of the genus Pseudokomewuia (20.5% of the palynocomplex) are characterized by higher contents of Fe, P, Ti, Nb, Ta, and W. The microphytoplankton bloom (an analog of the present-day red tides) in the late Oligocene Turtas Lake-Sea was probably caused by a greater contribution of nutrient substances from the continent during the transgression of this basin. Comparative analysis of the geochemical features of marine and continental Paleogene sediments from borehole no. 8 showed that the Turtas basin was either freshwater or had brackish water.

  20. A new genus of aplodontid rodent (Mammalia, Rodentia) from the late Oligocene of northern Junggar Basin, China.

    Science.gov (United States)

    Bi, Shundong; Meng, Jin; McLean, Sarah; Wu, Wenyu; Ni, Xijun; Ye, Jie

    2013-01-01

    A new genus and species of aplodontid rodent, Proansomys dureensis, from the late Oligocene of the northern Junggar Basin of China is described. The new genus is referred to as Ansomyinae because the ectoloph on the upper cheek teeth, although not fully crested, has attained the same characteristic bucket-handle-shaped configuration as other members of the subfamily. It represents the earliest record of the subfamily yet discovered in Asia and is more plesiomorphic than species of the genus Ansomys in having a partly crested ectoloph, a lower degree of lophodonty, and less complex tooth basins (lacking accessory lophules). Proansomys has transitional features between Prosciurus and Ansomys, suggesting that the Ansomyinae derived from a group of aplodontids related to Prosciurus, as did other advanced aplodontid rodents. This provides new light on the paleobiogeography of the Ansomyinae.

  1. Monocotyledon fruits and seeds, and an associated palynoflora from Eocene-Oligocene sediments of coastal central Queensland, Australia.

    Science.gov (United States)

    Dettmann; Clifford

    2000-07-01

    Fruits of Restionaceae and seeds of Typhaceae are described from a latest Eocene-Oligocene mudstone underlying oil shales in a subsurface sequence near Rockhampton, coastal central Queensland. The Restionaceae fruits are unilocular and encase a single pendulous orthotropous seed with a structured micropylar cap, which may be tannin filled. These are allocated to Restiocarpum gen. nov., which has as its type Restiocarpum latericum sp. nov., and four other taxa described herein; Restiocarpum tesselatum sp. nov., Restiocarpum verrucatum sp. nov., Restiocarpum laeve sp. nov., and Restiocarpum fusiforme sp. nov. Typhaspermum cooksoniae gen. et sp. nov., which accommodates asymmetric claviform seeds, is interpreted as a member of the Typhaceae based on the presence of a lid-like operculum, bitegmic wall, and chalazal cavity.Reconstruction of the source plant community emphasizes similarities to restiad swamps of present day Wallum (swamp heathland) vegetation which is extensively developed along the Queensland coast. Biogeographic implications for the Restionaceae and Typhaceae are discussed.

  2. The bivalve Glycymeris planicostalis as a high-resolution paleoclimate archive for Rupelian (Early Oligocene) of Central Europe

    Science.gov (United States)

    Walliser, E. O.; Schöne, B. R.; Tütken, T.; Zirkel, J.; Grimm, K. I.; Pross, J.

    2014-10-01

    Current global warming is likely to result in a unipolar glaciated world with unpredictable repercussions on atmospheric and oceanic circulation patterns. These changes are expected to affect seasonality as well as the frequency and intensity of decadal climate oscillations. To better constrain the mode and tempo of the anticipated changes, climatologists require high-resolution proxy data of time intervals in the past, e.g. the Early Oligocene during which boundary conditions were similar to those predicted for the near future. As demonstrated by the present study, pristinely preserved shells of the long-lived bivalve mollusk Glycymeris planicostalis from the late Rupelian of the Mainz Basin, Germany, provide an excellent archive to reconstruct changes of sea surface temperature on seasonal to inter-annual time scales. Their shells grew uninterruptedly during winter and summer and therefore recorded the full seasonal temperature amplitude that prevailed in the Mainz Basin 30 Ma ago. Absolute sea surface temperature data were faithfully reconstructed from δ18 Oshell values assuming a δ18Owater signature that was extrapolated from coeval sirenian tooth enamel. Extreme values ranged between 12.3 and 22.0°C and agree well with previous estimates based on planktonic foraminifera and shark teeth. However, summer and winter temperatures varied greatly on inter-annual time-scales. Winter and summer temperatures averaged over 40 annual increments of three specimens equaled 13.6 ± 0.8°C and 17.3 ± 1.2°C, respectively. Unless many samples are analyzed, this variability is hardly seen in foraminiferan tests. Our data also revealed decadal-scale oscillations of seasonal extremes which have - in the absence of appropriate climate archives - never been identified before for the Oligocene. This information can be highly relevant for numerical climate studies aiming to predict possible future climates in a unipolar glaciated or, ultimately, polar ice-free world.

  3. The earliest colubroid-dominated snake fauna from Africa: perspectives from the Late Oligocene Nsungwe Formation of southwestern Tanzania.

    Science.gov (United States)

    McCartney, Jacob A; Stevens, Nancy J; O'Connor, Patrick M

    2014-01-01

    The extant snake fauna has its roots in faunal upheaval occurring across the Paleogene-Neogene transition. On northern continents, this turnover is well established by the late early Miocene. However, this transition is poorly documented on southern landmasses, particularly on continental Africa, where no late Paleogene terrestrial snake assemblages are documented south of the equator. Here we describe a newly discovered snake fauna from the Late Oligocene Nsungwe Formation in the Rukwa Rift Basin of Tanzania. The fauna is small but diverse with eight identifiable morphotypes, comprised of three booids and five colubroids. This fauna includes Rukwanyoka holmani gen. et sp. nov., the oldest boid known from mainland Africa. It also provides the oldest fossil evidence for the African colubroid clade Elapidae. Colubroids dominate the fauna, comprising more than 75% of the recovered material. This is likely tied to local aridification and/or seasonality and mirrors the pattern of overturn in later snake faunas inhabiting the emerging grassland environments of Europe and North America. The early emergence of colubroid dominance in the Rukwa Rift Basin relative to northern continents suggests that the pattern of overturn that resulted in extant faunas happened in a more complex fashion on continental Africa than was previously realized, with African colubroids becoming at least locally important in the late Paleogene, either ahead of or as a consequence of the invasion of colubrids. The early occurrence of elapid snakes in the latest Oligocene of Africa suggests the clade rapidly spread from Asia to Africa, or arose in Africa, before invading Europe.

  4. The earliest colubroid-dominated snake fauna from Africa: perspectives from the Late Oligocene Nsungwe Formation of southwestern Tanzania.

    Directory of Open Access Journals (Sweden)

    Jacob A McCartney

    Full Text Available The extant snake fauna has its roots in faunal upheaval occurring across the Paleogene-Neogene transition. On northern continents, this turnover is well established by the late early Miocene. However, this transition is poorly documented on southern landmasses, particularly on continental Africa, where no late Paleogene terrestrial snake assemblages are documented south of the equator. Here we describe a newly discovered snake fauna from the Late Oligocene Nsungwe Formation in the Rukwa Rift Basin of Tanzania. The fauna is small but diverse with eight identifiable morphotypes, comprised of three booids and five colubroids. This fauna includes Rukwanyoka holmani gen. et sp. nov., the oldest boid known from mainland Africa. It also provides the oldest fossil evidence for the African colubroid clade Elapidae. Colubroids dominate the fauna, comprising more than 75% of the recovered material. This is likely tied to local aridification and/or seasonality and mirrors the pattern of overturn in later snake faunas inhabiting the emerging grassland environments of Europe and North America. The early emergence of colubroid dominance in the Rukwa Rift Basin relative to northern continents suggests that the pattern of overturn that resulted in extant faunas happened in a more complex fashion on continental Africa than was previously realized, with African colubroids becoming at least locally important in the late Paleogene, either ahead of or as a consequence of the invasion of colubrids. The early occurrence of elapid snakes in the latest Oligocene of Africa suggests the clade rapidly spread from Asia to Africa, or arose in Africa, before invading Europe.

  5. Diversity in the later Paleogene proboscidean radiation: a small barytheriid from the Oligocene of Dhofar Governorate, Sultanate of Oman

    Science.gov (United States)

    Seiffert, Erik R.; Nasir, Sobhi; Al-Harthy, Abdulrahman; Groenke, Joseph R.; Kraatz, Brian P.; Stevens, Nancy J.; Al-Sayigh, Abdul Razak

    2012-02-01

    Despite significant recent improvements to our understanding of the early evolution of the Order Proboscidea (elephants and their extinct relatives), geographic sampling of the group's Paleogene fossil record remains strongly biased, with the first ~30 million years of proboscidean evolution documented solely in near-coastal deposits of northern Africa. The considerable morphological disparity that is observable among the late Eocene and early Oligocene proboscideans of northern Africa suggests that other, as yet unsampled, parts of Afro-Arabia might have served as important centers for the early diversification of major proboscidean clades. Here we describe the oldest taxonomically diagnostic remains of a fossil proboscidean from the Arabian Peninsula, a partial mandible of Omanitherium dhofarensis (new genus and species), from near the base of the early Oligocene Shizar Member of the Ashawq Formation, in the Dhofar Governorate of the Sultanate of Oman. The molars and premolars of Omanitherium are morphologically intermediate between those of Arcanotherium and Barytherium from northern Africa, but its specialized lower incisors are unlike those of other known Paleogene proboscideans in being greatly enlarged, high-crowned, conical, and tusk-like. Omanitherium is consistently placed close to late Eocene Barytherium in our phylogenetic analyses, and we place the new genus in the Family Barytheriidae. Some features of Omanitherium, such as tusk-like lower second incisors, the possible loss of the lower central incisors, an enlarged anterior mental foramen, and inferred elongate mandibular symphysis and diminutive P2, suggest a possible phylogenetic link with Deinotheriidae, an extinct family of proboscideans whose origins have long been mysterious.

  6. Oligocene-Miocene paleoceanographic changes offshore the Wilkes Land Margin, Antarctica: dinoflagellate cyst and TEX86 analyses of DSDP Site 269

    Science.gov (United States)

    Bijl, Peter; Boterblom, Wilrieke H.; Sangiorgi, Francesca; Hartman, Julian D.; Peterse, Francien

    2017-04-01

    Although a lot of research has been conducted to characterize the onset of Antarctic glaciation at the Eocene-Oligocene transition, little is known about the subsequent evolution and fluctuations of the size of the Antarctic Ice Sheet (AIS). The discrepancy between the conclusions of Foster and Rohling (2013) (insensitive global cryosphere between 400-650 ppmv CO2) and variations in benthic foraminiferal δ18O records (0.5-1 ‰) illustrate the uncertainty in particularly the East AIS variability during the Oligocene and Miocene. Increasing awareness of the importance of oceanographic conditions on ice sheet melt emphasize the need to directly infer ice sheet volume fluctuations from sedimentary archives close to the Antarctic margin. In this study, dinoflagellate cyst (dinocyst) assemblages, dinocyst-based biostratigraphy and TEX86 from Deep Sea Drilling Project Site 269, offshore the Wilkes Land Margin (WLM), were used to reconstruct the paleoenvironment and paleoceanographic setting during the Oligocene and Miocene. Preliminary results are indicative of open ocean conditions, Southern Ocean fronts and high productivity waters. Furthermore, biomarker species were found, which are useful for stratigraphic dating. Research conducted at the continental rise of the WLM (Site U1356), by Bijl et al. (in prep.), has allowed for the calibration of dinocysts events of the Oligocene-Miocene Southern Ocean to the international time scale. Comparing the results of Site 269 to Site U1356 can thus provide an age constraint for this record. Correlating paleoceanographic changes between sites can provide insights into the variability of the EAIS during the Oligocene and Miocene, and will contribute to improving predictions of future changes in the Antarctic ice sheet.

  7. Satellite- and Epoch Differenced Precise Point Positioning Based on a Regional Augmentation Network

    Directory of Open Access Journals (Sweden)

    Bin Wu

    2012-06-01

    Full Text Available Precise Point Positioning (PPP has been demonstrated as a simple and effective approach for user positioning. The key issue in PPP is how to shorten convergence time and improve positioning efficiency. Recent researches mainly focus on the ambiguity resolution by correcting residual phase errors at a single station. The success of this approach (referred to hereafter as NORM-PPP is subject to how rapidly one can fix wide-lane and narrow-lane ambiguities to achieve the first ambiguity-fixed solution. The convergence time of NORM-PPP is receiver type dependent, and normally takes 15–20 min. Different from the general algorithm and theory by which the float ambiguities are estimated and the integer ambiguities are fixed, we concentrate on a differential PPP approach: the satellite- and epoch differenced (SDED approach. In general, the SDED approach eliminates receiver clocks and ambiguity parameters and thus avoids the complicated residual phase modeling procedure. As a further development of the SDED approach, we use a regional augmentation network to derive tropospheric delay and remaining un-modeled errors at user sites. By adding these corrections and applying the Robust estimation, the weak mathematic properties due to the ED operation is much improved. Implementing this new approach, we need only two epochs of data to achieve PPP positioning converging to centimeter-positioning accuracy. Using seven days of GPS data at six CORS stations in Shanghai, we demonstrate the success rate, defined as the case when three directions converging to desired positioning accuracy of 10 cm, reaches 100% when the interval between the two epochs is longer than 15 min. Comparing the results of 15 min’ interval to that of 10 min’, it is observed that the position RMS improves from 2.47, 3.95, 5.78 cm to 2.21, 3.93, 4.90 cm in the North, East and Up directions, respectively. Combining the SDED coordinates at the starting point and the ED relative

  8. Satellite- and epoch differenced precise point positioning based on a regional augmentation network.

    Science.gov (United States)

    Li, Haojun; Chen, Junping; Wang, Jiexian; Wu, Bin

    2012-01-01

    Precise Point Positioning (PPP) has been demonstrated as a simple and effective approach for user positioning. The key issue in PPP is how to shorten convergence time and improve positioning efficiency. Recent researches mainly focus on the ambiguity resolution by correcting residual phase errors at a single station. The success of this approach (referred to hereafter as NORM-PPP) is subject to how rapidly one can fix wide-lane and narrow-lane ambiguities to achieve the first ambiguity-fixed solution. The convergence time of NORM-PPP is receiver type dependent, and normally takes 15-20 min. Different from the general algorithm and theory by which the float ambiguities are estimated and the integer ambiguities are fixed, we concentrate on a differential PPP approach: the satellite- and epoch differenced (SDED) approach. In general, the SDED approach eliminates receiver clocks and ambiguity parameters and thus avoids the complicated residual phase modeling procedure. As a further development of the SDED approach, we use a regional augmentation network to derive tropospheric delay and remaining un-modeled errors at user sites. By adding these corrections and applying the Robust estimation, the weak mathematic properties due to the ED operation is much improved. Implementing this new approach, we need only two epochs of data to achieve PPP positioning converging to centimeter-positioning accuracy. Using seven days of GPS data at six CORS stations in Shanghai, we demonstrate the success rate, defined as the case when three directions converging to desired positioning accuracy of 10 cm, reaches 100% when the interval between the two epochs is longer than 15 min. Comparing the results of 15 min' interval to that of 10 min', it is observed that the position RMS improves from 2.47, 3.95, 5.78 cm to 2.21, 3.93, 4.90 cm in the North, East and Up directions, respectively. Combining the SDED coordinates at the starting point and the ED relative coordinates thereafter, we

  9. A machine-learning approach to measuring the escape of ionizing radiation from galaxies in the reionization epoch

    CERN Document Server

    Jensen, Hannes; Pelckmans, Kristiaan; Binggeli, Christian; Ausmees, Kristiina; Lundholm, Ulrika

    2016-01-01

    Recent observations of galaxies at $z \\gtrsim 7$, along with the low value of the electron scattering optical depth measured by the Planck mission, make galaxies plausible as dominant sources of ionizing photons during the epoch of reionization. However, scenarios of galaxy-driven reionization hinge on the assumption that the average escape fraction of ionizing photons is significantly higher for galaxies in the reionization epoch than in the local Universe. The NIRSpec instrument on the James Webb Space Telescope (JWST) will enable spectroscopic observations of large samples of reionization-epoch galaxies. While the leakage of ionizing photons will not be directly measurable from these spectra, the leakage is predicted to have an indirect effect on the spectral slope and the strength of nebular emission lines in the rest-frame ultraviolet and optical. Here, we apply a machine learning technique known as lasso regression on mock JWST/NIRSpec observations of simulated $z=7$ galaxies in order to obtain a model ...

  10. Modelling the 21 cm Signal From the Epoch of Reionization and Cosmic Dawn

    CERN Document Server

    Choudhury, T Roy; Majumdar, Suman; Ghara, Raghunath; Paranjape, Aseem; Mondal, Rajesh; Bharadwaj, Somnath; Samui, Saumyadip

    2016-01-01

    Studying the cosmic dawn and the epoch of reionization through the redshifted 21 cm line are among the major science goals of the SKA1. Their significance lies in the fact that they are closely related to the very first stars in the universe. Interpreting the upcoming data would require detailed modelling of the relevant physical processes. In this article, we focus on the theoretical models of reionization that have been worked out by various groups working in India with the upcoming SKA in mind. These models include purely analytical and semi-numerical calculations as well as fully numerical radiative transfer simulations. The predictions of the 21 cm signal from these models would be useful in constraining the properties of the early galaxies using the SKA data.

  11. Detection of an oxygen emission line from a high redshift galaxy in the reionization epoch

    CERN Document Server

    Inoue, Akio K; Matsuo, Hiroshi; Mawatari, Ken; Shimizu, Ikkoh; Shibuya, Takatoshi; Ota, Kazuaki; Yoshida, Naoki; Zackrisson, Erik; Kashikawa, Nobunari; Kohno, Kotaro; Umehata, Hideki; Hatsukade, Bunyo; Iye, Masanori; Matsuda, Yuichi; Okamoto, Takashi; Yamaguchi, Yuki

    2016-01-01

    The physical properties and elemental abundances of the interstellar medium in galaxies during cosmic reionization are important for understanding the role of galaxies in this process. We report the Atacama Large Millimeter/submillimeter Array detection of an oxygen emission line at a wavelength of 88 micrometers from a galaxy at an epoch about 700 million years after the Big Bang. The oxygen abundance of this galaxy is estimated at about one-tenth that of the Sun. The non-detection of far-infrared continuum emission indicates a deficiency of interstellar dust in the galaxy. A carbon emission line at a wavelength of 158 micrometers is also not detected, implying an unusually small amount of neutral gas. These properties might allow ionizing photons to escape into the intergalactic medium.

  12. Modelling the 21-cm Signal from the Epoch of Reionization and Cosmic Dawn

    Indian Academy of Sciences (India)

    T. Roy Choudhury; Kanan Datta; Suman Majumdar; Raghunath Ghara; Aseem Paranjape; Rajesh Mondal; Somnath Bharadwaj; Saumyadip Samui

    2016-12-01

    Studying the cosmic dawn and the epoch of reionization through the redshifted 21-cm line are among the major science goals of the SKA1. Their significance lies in the fact that they are closely related to the very first stars in the Universe. Interpreting the upcoming data would require detailed modelling of the relevant physical processes. In this article, we focus on the theoretical models of reionization that have been worked out by various groups working in India with the upcoming SKA in mind. These models include purely analytical and semi-numerical calculations as well as fully numerical radiative transfer simulations. The predictions of the 21-cm signal from these models would be useful in constraining the properties of the early galaxies using the SKA data.

  13. A Lyman Break Galaxy in the Epoch of Reionization from Hubble Space Telescope (HST) Grism Spectroscopy

    Science.gov (United States)

    Rhoads, James E.; Malhotra, Sangeeta; Stern, Daniel K.; Gardner, Jonathan P.; Dickinson, Mark; Pirzkal, Norbert; Spinrad, Hyron; Reddy, Naveen; Dey, Arjun; Hathi, Nimish; hide

    2013-01-01

    Slitless grism spectroscopy from space offers dramatic advantages for studying high redshift galaxies: high spatial resolution to match the compact sizes of the targets, a dark and uniform sky background, and simultaneous observation over fields ranging from five square arcminutes (HST) to over 1000 square arcminutes (Euclid). Here we present observations of a galaxy at z = 6.57 the end of the reioinization epoch identified using slitless HST grism spectra from the PEARS survey (Probing Evolution And Reionization Spectroscopically) and reconfirmed with Keck + DEIMOS. This high redshift identification is enabled by the depth of the PEARS survey. Substantially higher redshifts are precluded for PEARS data by the declining sensitivity of the ACS grism at greater than lambda 0.95 micrometers. Spectra of Lyman breaks at yet higher redshifts will be possible using comparably deep observations with IR-sensitive grisms.

  14. Measuring Light from the Epoch of Reionization with CIBER, the Cosmic Infrared Background Experiment

    CERN Document Server

    Zemcov, Michael; Battle, John; Bock, James J; Cooray, Asantha; Hristov, Viktor; Keating, Brian; Kim, Min-Gyu; Lee, Dae-Hee; Levenson, Louis; Mason, Peter; Matsumoto, Toshio; Matsuura, Shuji; Mitchell-Wynne, Ketron; Nam, Uk Won; Renbarger, Tom; Smidt, Joseph; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko

    2011-01-01

    Ultraviolet emission from the first generation of stars in the Universe ionized the intergalactic medium in a process which was completed by z~6; the wavelength of these photons has been redshifted by (1+z) into the near infrared today and can be measured using instruments situated above the Earth's atmosphere. First flying in February 2009, the Cosmic Infrared Background Experiment (CIBER) comprises four instruments housed in a single reusable sounding rocket borne payload. CIBER will measure spatial anisotropies in the extragalactic IR background caused by cosmological structure from the epoch of reionization using two broadband imaging instruments, make a detailed characterization of the spectral shape of the IR background using a low resolution spectrometer, and measure the absolute brightness of the Zodical light foreground with a high resolution spectrometer in each of our six science fields. This paper presents the scientific motivation for CIBER and details of its first two flights, including a review...

  15. The Influence of Indian Ocean Atmospheric Circulation on Warm Pool Hydroclimate During the Holocene Epoch

    Science.gov (United States)

    Tierney, J.E.; Oppo, D. W.; LeGrande, A. N.; Huang, Y.; Rosenthal, Y.; Linsley, B. K.

    2012-01-01

    Existing paleoclimate data suggest a complex evolution of hydroclimate within the Indo-Pacific Warm Pool (IPWP) during the Holocene epoch. Here we introduce a new leaf wax isotope record from Sulawesi, Indonesia and compare proxy water isotope data with ocean-atmosphere general circulation model (OAGCM) simulations to identify mechanisms influencing Holocene IPWP hydroclimate. Modeling simulations suggest that orbital forcing causes heterogenous changes in precipitation across the IPWP on a seasonal basis that may account for the differences in time-evolution of the proxy data at respective sites. Both the proxies and simulations suggest that precipitation variability during the September-November (SON) season is important for hydroclimate in Borneo. The preeminence of the SON season suggests that a seasonally lagged relationship between the Indian monsoon and Indian Ocean Walker circulation influences IPWP hydroclimatic variability during the Holocene.

  16. Confirmation and Significance of Caledonian Metallogenic Epoch for Gold Deposits in South China

    Institute of Scientific and Technical Information of China (English)

    王秀璋; 梁华英; 单强; 程景平; 夏萍

    2001-01-01

    Caledonian gold deposits are widely distributed in South China. They are developed in both South China Caledonian fold belt and adjacent Proterozoic Jiangnan uplift. The host rocks are Proterozoic metamorphosed microclastic rocks in the Jiangnan uplift and Proterozoic and Cambrian strata, as well as Chengjiang and Caledonian igneous bodies in the South China fold belt. The distinct differences between the Caledonian and the most developed Yenshanian gold deposits in South China are reflected in age and host-rock type, relations to Yenshanian magmatic activities, element association, mineral assemblage and gold deposit type. The stud ies have proven that the Caledonian epoch is a principal metallogenic period of gold deposits in South China. This conclusion is of very important enlightening significance in exploration of Caledonian gold deposits in South China as well as in other Caledonian fold belts and adjacent u plifts in China.

  17. Single Epoch GPS Deformation Signals Extraction and Gross Error Detection Technique Based on Wavelet Transform

    Institute of Scientific and Technical Information of China (English)

    WANG Jian; GAO Jingxiang; XU Changhui

    2006-01-01

    Wavelet theory is efficient as an adequate tool for analyzing single epoch GPS deformation signal. Wavelet analysis technique on gross error detection and recovery is advanced. Criteria of wavelet function choosing and Mallat decomposition levels decision are discussed. An effective deformation signal extracting method is proposed, that is wavelet noise reduction technique considering gross error recovery, which combines wavelet multi-resolution gross error detection results. Time position recognizing of gross errors and their repairing performance are realized. In the experiment, compactly supported orthogonal wavelet with short support block is more efficient than the longer one when discerning gross errors, which can obtain more finely analyses. And the shape of discerned gross error of short support wavelet is simpler than that of the longer one. Meanwhile, the time scale is easier to identify.

  18. A simulation calibrated limit on the HI power spectrum from the GMRT Epoch of Reionization experiment

    CERN Document Server

    Paciga, Gregory; Bandura, Kevin; Chang, Tzu-Ching; Gupta, Yashwant; Hirata, Christopher; Odegova, Julia; Pen, Ue-Li; Peterson, Jeffrey B; Roy, Jayanta; Shaw, Richard; Sigurdson, Kris; Voytek, Tabitha

    2013-01-01

    The GMRT Epoch of Reionization (EoR) experiment is an ongoing effort to measure the power spectrum from neutral hydrogen at high redshift. We have previously reported an upper limit of (70 mK)^2 at wavenumbers of k=0.65 h/Mpc using a basic piecewise-linear foreground subtraction. In this paper we explore the use of a singular value decomposition to remove foregrounds with fewer assumptions about the foreground structure. Using this method we also quantify, for the first time, the signal loss due to the foreground filter and present new power spectra adjusted for this loss, providing a revised measurement of a 2-sigma upper limit at (248 mK)^2 for k=0.50 h/Mpc. While this revised limit is larger than previously reported, we believe it to be more robust and still represents the best current constraints on reionization at z=8.6.

  19. Forecast for Epoch-of-Reionization as viewable by the PrimevAl Structure Telescope (PAST)

    CERN Document Server

    Peterson, J

    2004-01-01

    We present sensitivity forecasts for the PAST 21cm reionization observations and compare these with the measured sensitivity of a prototype array. We discuss the likely epoch-of-reionization structures and the redshifts that can be observed, and conclude that a 10,000 antenna PAST will be able to image ionized structures with its 1 million pixel map at 6

  20. Effect of a non null pressure on the evolution of perturbations in the matter dominated epoch

    CERN Document Server

    Herrero, A

    2003-01-01

    We analyze the effect of pressure on the evolution of perturbations of an Einstein-de Sitter Universe in the matter dominated epoch assuming an ideal gas equation of state. For the sake of simplicity the temperature is considered uniform. The goal of the paper is to examine the validity of the linear approximation. With this purpose the evolution equations are developed including quadratic terms in the derivatives of the metric perturbations and using coordinate conditions that, in the linear case, reduce to the longitudinal gauge. We obtain the general solution, in the coordinate space, of the evolution equation for the scalar mode, and, in the case of spherical symmetry, we express this solution in terms of unidimensional integrals of the initial conditions: the initial values of the Newtonian potential and its first time derivative. We find that the contribution of the initial first time derivative, which has been systematically forgotten, allows to form inhomogeneities similar to a cluster of galaxies sta...

  1. EXTREME HOST GALAXY GROWTH IN POWERFUL EARLY-EPOCH RADIO GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Barthel, Peter [Kapteyn Astronomical Institute, University of Groningen (Netherlands); Haas, Martin [Astronomisches Institut, Ruhr Universitaet, Bochum (Germany); Leipski, Christian [Max-Planck-Institut fuer Astronomie, Heidelberg (Germany); Wilkes, Belinda, E-mail: pdb@astro.rug.nl [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)

    2012-10-01

    During the first half of the universe's life, a heyday of star formation must have occurred because many massive galaxies are in place after that epoch in cosmic history. Our observations with the revolutionary Herschel Space Observatory reveal vigorous optically obscured star formation in the ultra-massive hosts of many powerful high-redshift 3C quasars and radio galaxies. This symbiotic occurrence of star formation and black hole driven activity is in marked contrast to recent results dealing with Herschel observations of X-ray-selected active galaxies. Three archetypal radio galaxies at redshifts 1.132, 1.575, and 2.474 are presented here, with inferred star formation rates of hundreds of solar masses per year. A series of spectacular coeval active galactic nucleus/starburst events may have formed these ultra-massive galaxies and their massive central black holes during their relatively short lifetimes.

  2. Spectral calibration requirements of radio interferometers for Epoch of Reionisation science with the SKA

    CERN Document Server

    Trott, Cathryn M

    2016-01-01

    Spectral features introduced by instrumental chromaticity of radio interferometers have the potential to negatively impact the ability to perform Epoch of Reionisation (EoR) and Cosmic Dawn (CD) science using the redshifted neutral hydrogen emission line from the early Universe. We describe instrument calibration choices that influence the spectral characteristics of the science data, and assess their impact on EoR statistical and tomographic experiments. Principally, we consider the intrinsic spectral response of the receiving antennas, embedded within a complete frequency-dependent primary beam response, and frequency-dependent instrument sampling. We assess different options for bandpass calibration. The analysis is applied to the proposed SKA1-Low EoR/CD experiments. We provide tolerances on the smoothness of the SKA station primary beam bandpass, to meet the scientific goals of statistical and tomographic (imaging) EoR programs. Two calibration strategies are tested: (1) fitting of each fine channel inde...

  3. Constraining Neutrino mass using the large scale HI distribution in the Post-reionization epoch

    CERN Document Server

    Pal, Ashis Kumar

    2016-01-01

    The neutral intergalactic medium in the post reionization epoch allows us to study cosmological structure formation through the observation of the redshifted 21 cm signal and the Lyman-alpha forest. We investigate the possibility of measuring the total neutrino mass through the suppression of power in the matter power spectrum. We investigate the possibility of measuring the neutrino mass through its imprint on the cross-correlation power spectrum of the 21-cm signal and the Lyman-alpha forest. We consider a radio-interferometric measurement of the 21 cm signal with a SKA1-mid like radio telescope and a BOSS like Lyman-alpha forest survey. A Fisher matrix analysis shows that at the fiducial redshift z = 2.5, a 10,000 hrs 21-cm observation distributed equally over 25 radio pointings and a Lyman-alpha forest survey with 30 quasars lines of sights in $1 {\\rm deg}^2$, allows us to measure $\\Omega_{\

  4. A physical model for cosmological simulations of galaxy formation: multi-epoch validation

    CERN Document Server

    Torrey, Paul; Genel, Shy; Sijacki, Debora; Springel, Volker; Hernquist, Lars

    2013-01-01

    We present a multi-epoch analysis of the galaxy populations formed within the cosmological hydrodynamical simulations presented in Vogelsberger et al. (2013). These simulations explore the performance of a recently implemented feedback model which includes primordial and metal line radiative cooling with self-shielding corrections; stellar evolution with associated mass loss and chemical enrichment; feedback by stellar winds; black hole seeding, growth and merging; and AGN quasar- and radio-mode heating with a phenomenological prescription for AGN electro-magnetic feedback. We illustrate the impact of the model parameter choices on the resulting simulated galaxy population properties at high and intermediate redshifts. We demonstrate that our scheme is capable of producing galaxy populations that broadly reproduce the observed galaxy stellar mass function extending from redshift z=0 to z=3. We also characterise the evolving galactic B-band luminosity function, stellar mass to halo mass ratio, star formation m...

  5. Radiation-induced large-scale structure during the reionization epoch: the autocorrelation function

    CERN Document Server

    Croft, Rupert A C

    2007-01-01

    The structures produced during the epoch of reionization by the action of radiation on neutral hydrogen are in principle different to those that arise through gravitational growth of initially small perturbations. We explore the difference between the two mechanisms using high resolution cosmological radiative transfer. Our computations use a Monte Carlo code which raytraces directly through SPH kernels without a grid, preserving the high spatial resolution of the underlying hydrodynamic simulation. Because the properties of the first sources of radiation are uncertain, we simulate a range of models with different source properties and recombination physics. We examine the morphology of the neutral hydrogren distribution and the reionization history in these models. We find that at fixed mean neutral fraction, structures are visually most affected by the existence of a lower limit in source luminosity, then by galaxy mass to light ratio, and are minimally affected by changes in the recombination rate and ampl...

  6. General Relativistic Energy Conditions The Hubble expansion in the epoch of galaxy formation

    CERN Document Server

    Visser, M

    1997-01-01

    The energy conditions of Einstein gravity (classical general relativity) are designed to extract as much information as possible from classical general relativity without enforcing a particular equation of state for the stress-energy. This systematic avoidance of the need to specify a particular equation of state is particularly useful in a cosmological setting --- since the equation of state for the cosmological fluid in a Friedmann-Robertson-Walker type universe is extremely uncertain. I shall show that the energy conditions provide simple and robust bounds on the behaviour of both the density and look-back time as a function of red-shift. I shall show that current observations suggest that the so-called strong energy condition (SEC) is violated sometime between the epoch of galaxy formation and the present. This implies that no possible combination of ``normal'' matter is capable of fitting the observational data.

  7. The Effect of Interplanetary Scintillation on Epoch of Reionisation Power Spectra

    CERN Document Server

    Trott, Cathryn M

    2015-01-01

    Interplanetary Scintillation (IPS) induces intensity fluctuations in small angular size astronomical radio sources via the distortive effects of spatially and temporally varying electron density associated with outflows from the Sun. These radio sources are a potential foreground contaminant signal for redshifted HI emission from the Epoch of Reionisation (EoR) because they yield time-dependent flux density variations in bright extragalactic point sources. Contamination from foreground continuum sources complicates efforts to discriminate the cosmological signal from other sources in the sky. In IPS, at large angles from the Sun applicable to EoR observations, weak scattering induces spatially and temporally correlated fluctuations in the measured flux density of sources in the field, potentially affecting the detectability of the EoR signal by inducing non-static variations in the signal strength. In this work, we explore the impact of interplanetary weak scintillation on EoR power spectrum measurements, acc...

  8. Commissioning and Science Forecasts for the Hydrogen Epoch of Reionization Array (HERA)

    Science.gov (United States)

    Parsons, Aaron; HERA Collaboration

    2016-01-01

    The HERA is a low-frequency radio interferometer aiming to make precise measurements of the power spectrum of fluctuations in 21cm emission from the Epoch of Reionization at z=13—6. This project was recently awarded development funding under the 2014 cycle of the National Science Foundation's Mid-Scale Innovations Program (MSIP). We present initial results from the commissioning and testing of the 19-element HERA prototype in South Africa, including measurements of the performance of HERA's 14-m dish and feed via reflectometry, beam mapping, and on-sky commissioning tests. We then forecast the science results that HERA will deliver once it reaches its full size of 352 elements. These forecasts include constraints on the 21cm power spectrum, the impact of these constraints on parametrized models of ionization, and their relevance to cosmological models. Construction of HERA-352 is pending the outcome of the 2016 NSF MSIP cycle.

  9. Detection of an oxygen emission line from a high-redshift galaxy in the reionization epoch.

    Science.gov (United States)

    Inoue, Akio K; Tamura, Yoichi; Matsuo, Hiroshi; Mawatari, Ken; Shimizu, Ikkoh; Shibuya, Takatoshi; Ota, Kazuaki; Yoshida, Naoki; Zackrisson, Erik; Kashikawa, Nobunari; Kohno, Kotaro; Umehata, Hideki; Hatsukade, Bunyo; Iye, Masanori; Matsuda, Yuichi; Okamoto, Takashi; Yamaguchi, Yuki

    2016-06-24

    The physical properties and elemental abundances of the interstellar medium in galaxies during cosmic reionization are important for understanding the role of galaxies in this process. We report the Atacama Large Millimeter/submillimeter Array detection of an oxygen emission line at a wavelength of 88 micrometers from a galaxy at an epoch about 700 million years after the Big Bang. The oxygen abundance of this galaxy is estimated at about one-tenth that of the Sun. The nondetection of far-infrared continuum emission indicates a deficiency of interstellar dust in the galaxy. A carbon emission line at a wavelength of 158 micrometers is also not detected, implying an unusually small amount of neutral gas. These properties might allow ionizing photons to escape into the intergalactic medium.

  10. Gravitationally neutral dark matter-dark antimatter universe crystal with epochs of decelerated and accelerated expansion

    Science.gov (United States)

    Gribov, I. A.; Trigger, S. A.

    2016-11-01

    A large-scale self-similar crystallized phase of finite gravitationally neutral universe (GNU)—huge GNU-ball—with spherical 2D-boundary immersed into an endless empty 3D- space is considered. The main principal assumptions of this universe model are: (1) existence of stable elementary particles-antiparticles with the opposite gravitational “charges” (M+gr and M -gr), which have the same positive inertial mass M in = |M ±gr | ≥ 0 and are equally presented in the universe during all universe evolution epochs; (2) the gravitational interaction between the masses of the opposite charges” is repulsive; (3) the unbroken baryon-antibaryon symmetry; (4) M+gr-M-gr “charges” symmetry, valid for two equally presented matter-antimatter GNU-components: (a) ordinary matter (OM)-ordinary antimatter (OAM), (b) dark matter (DM)-dark antimatter (DAM). The GNU-ball is weightless crystallized dust of equally presented, mutually repulsive (OM+DM) clusters and (OAM+DAM) anticlusters. Newtonian GNU-hydrodynamics gives the observable spatial flatness and ideal Hubble flow. The GNU in the obtained large-scale self-similar crystallized phase preserves absence of the cluster-anticluster collisions and simultaneously explains the observable large-scale universe phenomena: (1) the absence of the matter-antimatter clusters annihilation, (2) the self-similar Hubble flow stability and homogeneity, (3) flatness, (4) bubble and cosmic-net structures as 3D-2D-1D decrystallization phases with decelerative (a ≤ 0) and accelerative (a ≥ 0) expansion epochs, (5) the dark energy (DE) phenomena with Λ VACUUM = 0, (6) the DE and DM fine-tuning nature and predicts (7) evaporation into isolated huge M±gr superclusters without Big Rip.

  11. A Monster At Any Other Epoch: Are Intermediate Redshift ULIRGs the Progenitors of QSO Host Galaxies?

    Science.gov (United States)

    Rothberg, Barry; Fischer, Jackie; Rodrigues, Myriam; Pirzkal, Nor

    2015-08-01

    There is a clear progression from merger-induced SF to QSO activity via Ultraluminous Infrared Galaxies (ULIRGs). While not all mergers are ULIRGs, multi-wavelength imaging confirms that all local ULIRGs are mergers. At 0.4 1 are responsible for ˜ 70% of the co-moving IR density. At these earlier epochs ULIRGs contained more gas, formed stars faster, and their number density was much higher. At z>1 there are conflicting conclusions about ULIRGs. Many studies conclude they are massive star-forming galaxies, not major mergers nor AGN. Nearly all studies of ULIRGs at z > 0.4 have selected these systems via scaling observed 24μm or 170μm Spitzer fluxes to integrated 8-1000μm fluxes and inferring masses from scaling photometric fluxes or millimeter observations of CO gas emission. These methods often rely heavily on uncertain assumptions (e.g. gas conversions, SED fitting and templates). Instead, we have assembled a representative sample of "classically" selected ULIRGs (60 and 100μm IRAS fluxes and 12 and 25μm WISE fluxes) for 0.4 < z < 1.0 and obtained optical and near-IR imaging and spectroscopy from Hubble Space Telescope, Keck, and the Large Binocular Telescope. We use the same techniques for measuring the dynamical and BH masses of ULIRGs in the local Universe to measure these parameters in more distant systems. Unlike other methods, we directly measure the mass at an epoch when galaxy formation and evolution appears to have changed dramatically from what we see today and compare these intermediate redshift ULIRGs with their counterparts in the local Universe. Our restframe optical and UV spectroscopy also allow us to directly probe gas-metallicities, outflows, and measure the properties of their stellar populations. Our results indicate that these intermediate redshift ULIRGs are dynamically similar to their local counterparts.

  12. On the link between extreme floods and excess monsoon epochs in South Asia

    Energy Technology Data Exchange (ETDEWEB)

    Kale, Vishwas [University of Pune, Department of Geography, Pune (India)

    2012-09-15

    This paper provides a synoptic view of extreme monsoon floods on all the nine large rivers of South Asia and their association with the excess (above-normal) monsoon rainfall periods. Annual maximum flood series for 18 gauging stations spread over four countries (India, Pakistan, Bangladesh and Nepal) and long-term monsoon rainfall data were analyzed to ascertain whether the extreme floods were clustered in time and whether they coincided with multi-decade excess monsoon rainfall epochs at the basin level. Simple techniques, such as the Cramer's t-test, regression and Mann-Kendall (MK) tests and Hurst method were used to evaluate the trends and patterns of the flood and rainfall series. MK test reveals absence of any long-term tendency in all the series. However, the Cramer's t test and Hurst-Mandelbrot rescaled range statistic provide evidence that both rainfall and flood time series are persistent. Using the Cramer's t-test the excess monsoon epochs for each basin were identified. The excess monsoon periods for different basins were found to be highly asynchronous with respect to duration as well as the beginning and end. Three main conclusions readily emerge from the analyses. Extreme floods (>90th percentile) in South Asia show a tendency to cluster in time. About three-fourth of the extreme floods have occurred during the excess monsoon periods between {proportional_to}1840 and 2000 AD, implying a noteworthy link between the two. The frequency of large floods was higher during the post-1940 period in general and during three decades (1940s, 1950s and 1980s) in particular. (orig.)

  13. LOFAR insights into the epoch of reionization from the cross-power spectrum of 21 cm emission and galaxies

    NARCIS (Netherlands)

    Wiersma, R. P. C.; Ciardi, B.; Thomas, R. M.; Harker, G. J. A.; Zaroubi, S.; Bernardi, G.; Brentjens, M.; de Bruyn, A. G.; Daiboo, S.; Jelic, V.; Kazemi, S.; Koopmans, L. V. E.; Labropoulos, P.; Martinez, O.; Offringa, A.; Pandey, V. N.; Schaye, J.; Veligatla, V.; Vedantham, H.; Yatawatta, S.; Mellema, G.

    2013-01-01

    Using a combination of N-body simulations, semi-analytic models and radiative transfer calculations, we have estimated the theoretical cross-power spectrum between galaxies and the 21 cm emission from neutral hydrogen during the epoch of reionization. In accordance with previous studies, we find tha

  14. Combinations of Epoch Durations and Cut-Points to Estimate Sedentary Time and Physical Activity among Adolescents

    Science.gov (United States)

    Fröberg, Andreas; Berg, Christina; Larsson, Christel; Boldemann, Cecilia; Raustorp, Anders

    2017-01-01

    The purpose of the current study was to investigate how combinations of different epoch durations and cut-points affect the estimations of sedentary time and physical activity in adolescents. Accelerometer data from 101 adolescents were derived and 30 combinations were used to estimate sedentary time, light, moderate, vigorous, and combined…

  15. High-resolution VLBA Observations of Three 7 mm SiO Masers toward VX Sgr at Five Epochs

    Science.gov (United States)

    Su, J. B.; Shen, Z.-Q.; Chen, X.; Yi, Jiyune; Jiang, D. R.; Yun, Y. J.

    2012-07-01

    VX Sgr is a red supergiant at an adopted distance of 1.6 kpc with intense 43 GHz SiO maser emission. In this paper, we present the high-resolution very long baseline interferometry (VLBI) observations of SiO masers toward VX Sgr at five epochs. We used the Very Long Baseline Array to map the J = 1→0 (v = 1, 2) 28SiO masers and confirmed a ring-like structure. In the first two epochs, the v = 1 masers form a ring, but v = 2 maser spots residing only in the southern and northern regions do not form a complete ring. In the third epoch, the two masers are distributed in a ring structure and the v = 2 masers are a bit closer to the central star. In the last two epochs, many new maser spots appear and overlap each other. These overlapping maser spots can be related to the shock waves and reflect the collisional pumping. We compare the observations with the pumping models and speculate that the real pumping mechanism may be complex in VX Sgr and vary with time. The J = 1→0 (v = 0) 29SiO line emission is also detected, but is too weak to produce any VLBI map.

  16. Initial deep LOFAR observations of epoch of reionization windows. I. The north celestial pole : I. The north celestial pole

    NARCIS (Netherlands)

    Yatawatta, S.; de Bruyn, A. G.; Brentjens, M. A.; Labropoulos, P.; Pandey, V. N.; Kazemi, S.; Zaroubi, S.; Koopmans, L. V. E.; Offringa, A. R.; Jelic, V.; Rubi, O. Martinez; Veligatla, V.; Wijnholds, S. J.; Brouw, W. N.; Bernardi, G.; Ciardi, B.; Daiboo, S.; Harker, G.; Schaye, J.; Thomas, R.; Vedantham, H.; Chapman, E.; Abdalla, F. B.; Alexov, A.; Anderson, J.; Avruch, I. M.; Batejat, F.; Bell, M. E.; Bell, M. R.; Bentum, M.; Best, P.; Bonafede, A.; Bregman, J.; Breitling, F.; van de Brink, R. H.; Broderick, J. W.; Brueggen, M.; Conway, J.; de Gasperin, F.; de Geus, E.; Duscha, S.; Falcke, H.; Fallows, R. A.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Griessmeier, J. M.; Gunst, A. W.; Hassall, T. E.; Hessels, J. W. T.; Hoeft, M.; Iacobelli, M.; Juette, E.; Karastergiou, A.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; van Leeuwen, J.; Maat, P.; Mann, G.; McKean, J. P.; Mevius, M.; Mol, J.D.; Munk, H.; Nijboer, R.; Noordam, J. E.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Rottgering, H. J. A.; Sluman, J.; Smirnov, O.; Stappers, B.; Steinmetz, M.; Tagger, M.; Tang, Y.; Tasse, C.; ter Veen, S.; Vermeulen, R.; van Weeren, R. J.; Wise, M.; Wucknitz, O.; Zarka, P.; Mellema, G.

    2013-01-01

    Aims: The aim of the LOFAR epoch of reionization (EoR) project is to detect the spectral fluctuations of the redshifted HI 21 cm signal. This signal is weaker by several orders of magnitude than the astrophysical foreground signals and hence, in order to achieve this, very long integrations, accurat

  17. Integrated magnetobiostratigraphy at the Oligocene/Miocene transition in the southwestern Atlantic Ocean (DSDP Leg 72, Hole 516F)

    Science.gov (United States)

    Gennari, Rocco; Persico, Davide; Florindo, Fabio; Turco, Elena; Villa, Giuliana

    2014-05-01

    A high-resolution integrated magnetostratigraphic and biostratigraphic (planktonic foraminifera and calcareous nannofossils) record of the interval encompassing the Oligocene/Miocene transition (OMT) at DSDP Hole 516F is here presented. This stratigraphic interval was previously studied by Berggren et al. (1983), Pujol (1983) and Spezzaferri (1994), although with a lower sample resolution. The magnetobiostratigraphic results of Berggren et al. (1983) are, moreover, considered as reference data for the age calibration of several bioevents along the OMT (Gradstein et al., 2012). Dealing with the same stratigraphic interval, other authors (Pagani et al., 2000; Plancq et al., 2012) based their paleoceanographic reconstruction on age model derived by Berggren et al. (1983). Our high-resolution integrated stratigraphy approach allowed us to obtain: 1) a more detailed succession of magnetic reversals across the OMT, including a better constraining of the base of Subchron C6Cn.2n, which formally defines the base of the Neogene (Steininger et al., 1997); 2) an integrated planktonic foraminifer and calcareous nannofossil quantitative biostratigraphy across the OMT. Particular focus has been addressed to the Lowest Common Occurrence of Paragloborotalia kugleri and the Highest Occurrences of Sphenolithus delphix and Sphenolithus capricornutus, which approximate the O/M boundary; 3) an updated age model of the OMT at Hole 516F. Finally, the new data here presented contributed to a critical review of the calcareous planktonic biostratigraphy across the OMT. References Berggren, W.A., Aubry, M.P. and Hamilton, N., 1983. Neogene magnetobiostratigraphy of deep sea drilling project site 516 (Rio Grande Rise, South Atlantic). In: Barker, P., et al. (Eds.), Initial Reports of the Deep Sea Drilling Project, 72, 675-713. Pagani, M., Arthur, M. A. and Freeman, K. H. 2000. Variations in Miocene phytoplankton growth rates in the southwest Atlantic: Evidence for changes in ocean circulation

  18. Diversity and distribution patterns of the Oligocene and Miocene decapod crustaceans (Crustacea: Malacostraca) of the Western and Central Paratethys

    Science.gov (United States)

    Hyžný, Matúš

    2017-01-01

    Decapod associations have been significant components of marine habitats throughout the Cenozoic when the major diversification of the group occurred. In this respect, the circum-Mediterranean area is of particular interest due to its complex palaeogeographic history. During the Oligo-Miocene, it was divided in two major areas, Mediterranean and Paratethys. Decapod crustaceans from the Paratethys Sea have been reported in the literature since the 19th century, but only recent research advances allow evaluation of the diversity and distribution patterns of the group. Altogether 176 species-level taxa have been identified from the Oligocene and Miocene of the Western and Central Paratethys. Using the three-dimensional NMDS analysis, the composition of decapod crustacean faunas of the Paratethys shows significant differences through time. The Ottnangian and Karpatian decapod associations were similar to each other both taxonomically and in the mode of preservation, and they differed taxonomically from the Badenian ones. The Early Badenian assemblages also differed taxonomically from the Late Badenian ones. The time factor, including speciation, immigration from other provinces and/or (local or global) extinction, can explain temporal differences among assemblages within the same environment. High decapod diversity during the Badenian was correlated with the presence of reefal settings. The Badenian was the time with the highest decapod diversity, which can, however, be a consequence of undersampling of other time slices. Whereas the Ottnangian and Karpatian decapod assemblages are preserved virtually exclusively in the siliciclastic “Schlier”-type facies that originated in non-reefal offshore environments, carbonate sedimentation and the presence of reefal environments during the Badenian in the Central Paratethys promoted thriving of more diverse reef-associated assemblages. In general, Paratethyan decapods exhibited homogeneous distribution during the Oligo

  19. Diversity and distribution patterns of the Oligocene and Miocene decapod crustaceans (Crustacea: Malacostraca of the Western and Central Paratethys

    Directory of Open Access Journals (Sweden)

    Hyžný Matúš

    2016-10-01

    Full Text Available Decapod associations have been significant components of marine habitats throughout the Cenozoic when the major diversification of the group occurred. In this respect, the circum-Mediterranean area is of particular interest due to its complex palaeogeographic history. During the Oligo-Miocene, it was divided in two major areas, Mediterranean and Paratethys. Decapod crustaceans from the Paratethys Sea have been reported in the literature since the 19th century, but only recent research advances allow evaluation of the diversity and distribution patterns of the group. Altogether 176 species-level taxa have been identified from the Oligocene and Miocene of the Western and Central Paratethys. Using the three-dimensional NMDS analysis, the composition of decapod crustacean faunas of the Paratethys shows significant differences through time. The Ottnangian and Karpatian decapod associations were similar to each other both taxonomically and in the mode of preservation, and they differed taxonomically from the Badenian ones. The Early Badenian assemblages also differed taxonomically from the Late Badenian ones. The time factor, including speciation, immigration from other provinces and/or (local or global extinction, can explain temporal differences among assemblages within the same environment. High decapod diversity during the Badenian was correlated with the presence of reefal settings. The Badenian was the time with the highest decapod diversity, which can, however, be a consequence of undersampling of other time slices. Whereas the Ottnangian and Karpatian decapod assemblages are preserved virtually exclusively in the siliciclastic “Schlier”-type facies that originated in non-reefal offshore environments, carbonate sedimentation and the presence of reefal environments during the Badenian in the Central Paratethys promoted thriving of more diverse reef-associated assemblages. In general, Paratethyan decapods exhibited homogeneous distribution

  20. Diversity and distribution patterns of the Oligocene and Miocene decapod crustaceans (Crustacea: Malacostraca) of the Western and Central Paratethys

    Science.gov (United States)

    Hyžný, Matúš

    2016-10-01

    Decapod associations have been significant components of marine habitats throughout the Cenozoic when the major diversification of the group occurred. In this respect, the circum-Mediterranean area is of particular interest due to its complex palaeogeographic history. During the Oligo-Miocene, it was divided in two major areas, Mediterranean and Paratethys. Decapod crustaceans from the Paratethys Sea have been reported in the literature since the 19th century, but only recent research advances allow evaluation of the diversity and distribution patterns of the group. Altogether 176 species-level taxa have been identified from the Oligocene and Miocene of the Western and Central Paratethys. Using the three-dimensional NMDS analysis, the composition of decapod crustacean faunas of the Paratethys shows significant differences through time. The Ottnangian and Karpatian decapod associations were similar to each other both taxonomically and in the mode of preservation, and they differed taxonomically from the Badenian ones. The Early Badenian assemblages also differed taxonomically from the Late Badenian ones. The time factor, including speciation, immigration from other provinces and/or (local or global) extinction, can explain temporal differences among assemblages within the same environment. High decapod diversity during the Badenian was correlated with the presence of reefal settings. The Badenian was the time with the highest decapod diversity, which can, however, be a consequence of undersampling of other time slices. Whereas the Ottnangian and Karpatian decapod assemblages are preserved virtually exclusively in the siliciclastic "Schlier"-type facies that originated in non-reefal offshore environments, carbonate sedimentation and the presence of reefal environments during the Badenian in the Central Paratethys promoted thriving of more diverse reef-associated assemblages. In general, Paratethyan decapods exhibited homogeneous distribution during the Oligo

  1. A FLUX SCALE FOR SOUTHERN HEMISPHERE 21 cm EPOCH OF REIONIZATION EXPERIMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, Daniel C.; Bowman, Judd [School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States); Parsons, Aaron R.; Ali, Zaki; Pober, Jonathan C. [Astronomy Department, University of California, Berkeley, CA (United States); Aguirre, James E.; Moore, David F. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA (United States); Bradley, Richard F. [Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA (United States); Carilli, Chris L. [National Radio Astronomy Observatory, Socorro, NM (United States); DeBoer, David R.; Dexter, Matthew R.; MacMahon, Dave H. E. [Radio Astronomy Lab., University of California, Berkeley, CA (United States); Gugliucci, Nicole E.; Klima, Pat [National Radio Astronomy Observatory, Charlottesville, VA (United States); Manley, Jason R.; Walbrugh, William P. [Square Kilometer Array, South Africa Project, Cape Town (South Africa); Stefan, Irina I. [Cavendish Laboratory, Cambridge (United Kingdom)

    2013-10-20

    We present a catalog of spectral measurements covering a 100-200 MHz band for 32 sources, derived from observations with a 64 antenna deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) in South Africa. For transit telescopes such as PAPER, calibration of the primary beam is a difficult endeavor and errors in this calibration are a major source of error in the determination of source spectra. In order to decrease our reliance on an accurate beam calibration, we focus on calibrating sources in a narrow declination range from –46° to –40°. Since sources at similar declinations follow nearly identical paths through the primary beam, this restriction greatly reduces errors associated with beam calibration, yielding a dramatic improvement in the accuracy of derived source spectra. Extrapolating from higher frequency catalogs, we derive the flux scale using a Monte Carlo fit across multiple sources that includes uncertainty from both catalog and measurement errors. Fitting spectral models to catalog data and these new PAPER measurements, we derive new flux models for Pictor A and 31 other sources at nearby declinations; 90% are found to confirm and refine a power-law model for flux density. Of particular importance is the new Pictor A flux model, which is accurate to 1.4% and shows that between 100 MHz and 2 GHz, in contrast with previous models, the spectrum of Pictor A is consistent with a single power law given by a flux at 150 MHz of 382 ± 5.4 Jy and a spectral index of –0.76 ± 0.01. This accuracy represents an order of magnitude improvement over previous measurements in this band and is limited by the uncertainty in the catalog measurements used to estimate the absolute flux scale. The simplicity and improved accuracy of Pictor A's spectrum make it an excellent calibrator in a band important for experiments seeking to measure 21 cm emission from the epoch of reionization.

  2. High-resolution magneto-biostratigraphy of the early Eocene to early Oligocene from Indian Ocean Hole 711A and Italian Monte Cagnero section

    Science.gov (United States)

    Savian, J. F.; Jovane, L.; Coccioni, R.; Frontalini, F.; Bohaty, S.; Wilson, P.; Roberts, A. P.; Florindo, F.; Trindade, R.

    2013-05-01

    One of the main challenges in the integration and analysis of palaeorecords is development of high-resolution age models. An accurate age control is fundamental for the reliable determination of sequences of events in the geological record. The early Eocene to the early Oligocene interval witnessed major changes in Earth's paleoclimate and paleogeography. Stable isotope records (δ18O and δ13C) from pelagic foraminifera for this time period show a long-term cooling trend which ends with an abrupt step, the Oi-1, near the Eocene/Oligocene transition at ~34 Ma, interpreted as the onset of glaciation in Antarctica. Several mechanisms have been proposed as the cause for this event, including the opening of the Southern Ocean, the decrease in atmospheric greenhouse gases, and the closure of the Neo-Tethys (STENT). Superimposed on this long-term cooling trend, some anomalous warming events occur, from which the middle Eocene climatic optimum (MECO) at 40 Ma is the most important. Here we report a high-resolution integrated age model of early Eocene-early Oligocene successions from two sites (Monte Cagnero, Central Italy and ODP Hole 711A, Indian Ocean), using magnetostratigraphy and biostratigraphy, and we also show lithostratigraphy, environmental magnetism, CaCO3, and isotope records on bulk carbonate. In parallel, we provide a high-resolution rock magnetic study of these sections including environmental magnetism data (magnetic susceptibility, ARM, IRM, and BIRM), IRM acquisition, thermomagnetic curves, hysteresis and FORC diagrams. Through these data, the main climatic events are recognized in these sections by the ubiquitous occurrence of non-interacting SD magnetite (in a mixture with fine hematite in the inland sections) associated with spikes in geochemical and isotopic data. These paleorecords will contribute to better understanding of the Eocene and Oligocene global climatic changes.

  3. A partial braincase and other skeletal remains of Oligocene angel sharks (Chondrichthyes, Squatiniformes) from northwest Belgium, with comments on squatinoid taxonomy

    OpenAIRE

    Mollen, F.H.; Bakel, van, P.J.T.; Jagt, J.W.M.

    2016-01-01

    A detailed redescription of a chondrocranium from the basal Boom Clay Formation (Rupelian, Upper Oligocene) at the SVK clay pit, Sint-Niklaas (province of Oost-Vlaanderen, Belgium), previously assigned to the sawshark Pristiophorus rupeliensis, is presented. The chondrocranium is re-identified as that of an angel shark (Squatinidae), based on comparative anatomy of extant Squatina, inclusive of CT scans of Squatina africana, S. australis, S. dumeril, S. guggenheim and S. squatina, with differ...

  4. The European ruminants during the "Microbunodon Event" (MP28, Latest Oligocene): impact of climate changes and faunal event on the ruminant evolution.

    Science.gov (United States)

    Mennecart, Bastien

    2015-01-01

    The Earth already experienced numerous episodes of global warming and cooling. One of the latest impressive events of temperature rising was the Late Oligocene Warming that occurred around 25 Mya. An increase of the marine temperature of 2 to 4°C has been observed in a short time interval. In Europe, this major climatic event can be correlated to the continental faunal turnover "Microbunodon Event". This event is marked by a huge faunal turnover (40% of the ungulate fauna during the first 500k years) and environmental changes. Drier conditions associated to the appearance of the seasonality lead to new environmental conditions dominated by wooded savannahs. This is correlated to a major arrival of Asiatic immigrants. Moreover, from a homogenous fauna during the main part of the Oligocene, local climatic variations between the European Western coast and the more central Europe could have provided faunal regionalism during the latest Oligocene and earliest Miocene. Considering the ruminants, this event is the major ever known for this group in Europe. A total renewal at the family level occurred. Thanks to a precise stratigraphic succession, major evolutionary elements are highlighted. Typical Oligocene species, mainly Tragulina, were adapted to wooded environments and were leaves/fruits eaters. They disappeared at the end of MP27 or the early MP28. This corresponds to the appearance of the Asiatic immigrants. The Tragulina (Lophiomerycidae, Bachitheriidae) and stem Pecora gave way to more derived stem and maybe crown Pecora (e.g. "Amphitragulus", Babameryx, Dremotherium). These newcomers were adapted to more open environments and mixed feeding. The disappearance of the Tragulina is probably linked to environmental and vegetation changes, and competition. They give way to more derived ruminants having a more efficient metabolism in drier conditions and a better assimilation of less energetic food.

  5. The European Ruminants during the “Microbunodon Event” (MP28, Latest Oligocene): Impact of Climate Changes and Faunal Event on the Ruminant Evolution

    Science.gov (United States)

    Mennecart, Bastien

    2015-01-01

    The Earth already experienced numerous episodes of global warming and cooling. One of the latest impressive events of temperature rising was the Late Oligocene Warming that occurred around 25 Mya. An increase of the marine temperature of 2 to 4°C has been observed in a short time interval. In Europe, this major climatic event can be correlated to the continental faunal turnover “Microbunodon Event”. This event is marked by a huge faunal turnover (40% of the ungulate fauna during the first 500k years) and environmental changes. Drier conditions associated to the appearance of the seasonality lead to new environmental conditions dominated by wooded savannahs. This is correlated to a major arrival of Asiatic immigrants. Moreover, from a homogenous fauna during the main part of the Oligocene, local climatic variations between the European Western coast and the more central Europe could have provided faunal regionalism during the latest Oligocene and earliest Miocene. Considering the ruminants, this event is the major ever known for this group in Europe. A total renewal at the family level occurred. Thanks to a precise stratigraphic succession, major evolutionary elements are highlighted. Typical Oligocene species, mainly Tragulina, were adapted to wooded environments and were leaves/fruits eaters. They disappeared at the end of MP27 or the early MP28. This corresponds to the appearance of the Asiatic immigrants. The Tragulina (Lophiomerycidae, Bachitheriidae) and stem Pecora gave way to more derived stem and maybe crown Pecora (e.g. “Amphitragulus”, Babameryx, Dremotherium). These newcomers were adapted to more open environments and mixed feeding. The disappearance of the Tragulina is probably linked to environmental and vegetation changes, and competition. They give way to more derived ruminants having a more efficient metabolism in drier conditions and a better assimilation of less energetic food. PMID:25692298

  6. The European ruminants during the "Microbunodon Event" (MP28, Latest Oligocene: impact of climate changes and faunal event on the ruminant evolution.

    Directory of Open Access Journals (Sweden)

    Bastien Mennecart

    Full Text Available The Earth already experienced numerous episodes of global warming and cooling. One of the latest impressive events of temperature rising was the Late Oligocene Warming that occurred around 25 Mya. An increase of the marine temperature of 2 to 4°C has been observed in a short time interval. In Europe, this major climatic event can be correlated to the continental faunal turnover "Microbunodon Event". This event is marked by a huge faunal turnover (40% of the ungulate fauna during the first 500k years and environmental changes. Drier conditions associated to the appearance of the seasonality lead to new environmental conditions dominated by wooded savannahs. This is correlated to a major arrival of Asiatic immigrants. Moreover, from a homogenous fauna during the main part of the Oligocene, local climatic variations between the European Western coast and the more central Europe could have provided faunal regionalism during the latest Oligocene and earliest Miocene. Considering the ruminants, this event is the major ever known for this group in Europe. A total renewal at the family level occurred. Thanks to a precise stratigraphic succession, major evolutionary elements are highlighted. Typical Oligocene species, mainly Tragulina, were adapted to wooded environments and were leaves/fruits eaters. They disappeared at the end of MP27 or the early MP28. This corresponds to the appearance of the Asiatic immigrants. The Tragulina (Lophiomerycidae, Bachitheriidae and stem Pecora gave way to more derived stem and maybe crown Pecora (e.g. "Amphitragulus", Babameryx, Dremotherium. These newcomers were adapted to more open environments and mixed feeding. The disappearance of the Tragulina is probably linked to environmental and vegetation changes, and competition. They give way to more derived ruminants having a more efficient metabolism in drier conditions and a better assimilation of less energetic food.

  7. Period, epoch and prediction errors of ephemeris from continuous sets of timing measurements

    CERN Document Server

    Deeg, Hans J

    2015-01-01

    Space missions such as Kepler and CoRoT have led to large numbers of eclipse or transit measurements in nearly continuous time series. This paper shows how to obtain the period error in such measurements from a basic linear least-squares fit, and how to correctly derive the timing error in the prediction of future transit or eclipse events. Assuming strict periodicity, a formula for the period error of such time series is derived: sigma_P = sigma_T (12/( N^3-N))^0.5, where sigma_P is the period error; sigma_T the timing error of a single measurement and N the number of measurements. Relative to the iterative method for period error estimation by Mighell & Plavchan (2013), this much simpler formula leads to smaller period errors, whose correctness has been verified through simulations. For the prediction of times of future periodic events, the usual linear ephemeris where epoch errors are quoted for the first time measurement, are prone to overestimation of the error of that prediction. This may be avoided...

  8. Multi-band, Multi-epoch Observations of the Transiting Warm Jupiter WASP-80b

    CERN Document Server

    Fukui, Akihiko; Ikoma, Masahiro; Narita, Norio; Onitsuka, Masahiro; Ita, Yoshifusa; Onozato, Hiroki; Nishiyama, Shogo; Baba, Haruka; Ryu, Tsuguru; Hirano, Teruyuki; Hori, Yasunori; Kurosaki, Kenji; Kawauchi, Kiyoe; Takahashi, Yasuhiro H; Nagayama, Takahiro; Tamura, Motohide; Kawai, Nobuyuki; Kuroda, Daisuke; Nagayama, Shogo; Ohta, Kouji; Shimizu, Yasuhiro; Yanagisawa, Kenshi; Yoshida, Michitoshi; Izumiura, Hideyuki

    2014-01-01

    WASP-80b is a warm Jupiter transiting a bright late-K dwarf, providing a good opportunity to extend the atmospheric study of hot Jupiters toward the lower temperature regime. We report multi-band, multi-epoch transit observations of WASP-80b by using three ground-based telescopes covering from optical (g', Rc, and Ic bands) to near infrared (NIR; J, H, and Ks bands) wavelengths. We observe five primary transits, each of which in three or four different bands simultaneously, obtaining 17 independent transit light curves. Combining them with previous works, we find that the observed transmission spectrum is largely consistent with both a solar-abundance and thick-cloud atmospheric models at 1.7-$\\sigma$ discrepancy level. On the other hand, we find a marginal spectral rise in optical region compared to NIR region at 2.9-$\\sigma$ level, which possibly indicates the existence of haze in the atmosphere. We simulate theoretical transmission spectra for a solar-abundance but hazy atmosphere, finding that a model wit...

  9. Superposed epoch analysis of storm time response of the ionosphere-thermosphere (IT) system

    Science.gov (United States)

    Oliveira, D. M.; Zesta, E.; Connor, H.; Su, Y. J.; Sutton, E. K.; Huang, C. Y.; Ober, D. M.; Delay, S. H.; Schuck, P. W.

    2015-12-01

    The thermosphere-ionosphere system response to energy input by Joule heating via Poynting flux and auroral precipitation is strongly intensified during times with high geomagnetic activity or during geomagnetic storms. The most dramatic thermospheric response is the intensification and upwelling of the thermospheric mass density. The neutral mass density is not only a key parameter to understanding the solar wind - IT coupling, but also plays an important role in understanding satellite orbital drag, which in turn impacts satellite position predictions. Results of numerical simulations and satellite observations (CHAMP and GRACE) have shown that the neutral mass density is rapidly intensified (within minutes) after the initial storm shock impact and also after the onset of storm main phase. This almost immediate response is typical of CME-driven storms in which the neutral density is enhanced first in the dayside polar cap and the intensification subsequently spreads out to all magnetic local time regions and lower latitude regions. We perform a superposed epoch analysis using CHAMP and GRACE satellite data as well as DMSP data to study the spatial and temporal distribution of the measured Poynting flux and neutral density response during the main phase of storms of different intensity. We also examine the correlation characteristics between Poynting flux and neutral density response, in space and time during the storm.

  10. Study of Redshifted HI from the Epoch of Reionization with Drift scan

    CERN Document Server

    Paul, Sourabh; Subrahmanyan, Ravi; Shankar, N Udaya; Dwarakanath, K S; Deshpande, Avinash A; Bernardi, Gianni; Bowman, Judd D; Briggs, Frank; Cappallo, Roger J; Corey, Brian E; Emrich, David; Gaensler, Bryan M; Goeke, Robert F; Greenhill, Lincoln J; Hazelton, Bryna J; Hewitt, Jacqueline N; Johnston-Hollitt, Melanie; Kaplan, David L; Kasper, Justin C; Kratzenberg, Eric; Lonsdale, Colin J; Lynch, Mervyn J; McWhirter, S Russell; Mitchell, Daniel A; Morales, Miguel F; Morgan, Edward H; Oberoi, Divya; Ord, Stephen M; Prabu, Thiagaraj; Rogers, Alan E E; Roshi, Anish A; Srivani, K S; Tingay, Steven J; Wayth, Randall B; Waterson, Mark; Webster, Rachel L; Whitney, Alan R; Williams, Andrew J; Williams, Christopher L

    2014-01-01

    The detection of the Epoch of Reionization (EoR) in the redshifted 21-cm line is a challenging task. Here we formulate the detection of the EoR signal using the drift scan strategy. This method potentially has better instrumental stability as compared to the case where a single patch of sky is tracked. We demonstrate that the correlation time between measured visibilities could extend up to 1-2 hr for an interferometer array such as the Murchison Widefield Array (MWA), which has a wide primary beam. We estimate the EoR power based on cross-correlation of visibilities across time and show that the drift scan strategy is capable of the detection of the EoR signal with comparable/better signal-to-noise as compared to the tracking case. We also estimate the visibility correlation for a set of bright point sources and argue that the statistical inhomogeneity of bright point sources might allow their separation from the EoR signal.

  11. Study of redshifted H I from the epoch of reionization with drift scan

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Sourabh; Sethi, Shiv K.; Subrahmanyan, Ravi; Shankar, N. Udaya; Dwarakanath, K. S.; Deshpande, Avinash A. [Raman Research Institute, Bangalore (India); Bernardi, Gianni [Square Kilometre Array South Africa (SKA SA), 3rd Floor, The Park, Park Road, Pinelands 7405 (South Africa); Bowman, Judd D. [Arizona State University, Tempe, AZ85281 (United States); Briggs, Frank; Gaensler, Bryan M. [ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), 44 Rosehill Street, Redfern, NSW 2016 (Australia); Cappallo, Roger J.; Corey, Brian E.; Goeke, Robert F. [MIT Haystack Observatory, Westford, MA 01886 (United States); Emrich, David [Curtin University, Perth (Australia); Greenhill, Lincoln J.; Kasper, Justin C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hazelton, Bryna J. [University of Washington, Seattle, WA 98195 (United States); Hewitt, Jacqueline N. [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, 37-241, Cambridge, MA 02139 (United States); Johnston-Hollitt, Melanie [Victoria University of Wellington, P.O. Box 600, Wellington 6140 (New Zealand); Kaplan, David L., E-mail: sourabh@rri.res.in, E-mail: sethi@rri.res.in [University of Wisconsin-Milwaukee, Milwaukee, WI 53201 (United States); and others

    2014-09-20

    Detection of the epoch of reionization (EoR) in the redshifted 21 cm line is a challenging task. Here, we formulate the detection of the EoR signal using the drift scan strategy. This method potentially has better instrumental stability compared to the case where a single patch of sky is tracked. We demonstrate that the correlation time between measured visibilities could extend up to 1-2 hr for an interferometer array such as the Murchison Widefield Array, which has a wide primary beam. We estimate the EoR power based on a cross-correlation of visibilities over time and show that the drift scan strategy is capable of detecting the EoR signal with a signal to noise that is comparable/better compared to the tracking case. We also estimate the visibility correlation for a set of bright point sources and argue that the statistical inhomogeneity of bright point sources might allow their separation from the EoR signal.

  12. Metallogenic epoch and genesis of the gold deposits in Jiaodong Peninsula, Eastern China: a regional review

    Institute of Scientific and Technical Information of China (English)

    YANG Liqiang; DENG Jun; GE Liangsheng; WANG Qingfei; ZHANG Jing; GAO Bangfei; JIANG Shaoqing; XU Hao

    2007-01-01

    Gold deposits are characterized by multi-sources, superimposition, large scale and temporal-spatial concentration in Jiaodong Peninsula, Eastern China. In this paper, we review the history and the development of the study on metallogenic chronology and genesis of gold deposits, summarize the main features of superimposed metallogenesis, provide evidence of the Mesozoic complex metallogenic system, and point out some problems for further research of Jiaodong gold deposit cluster from a regional view. Although gold deposits are different in genetic types, ore-forming materials and geological settings, our research indicates that the accumulation and emplacement of the ore-forming materials are temporally-spatially concentrated on a large scale, and the main metallogenic epoch of Jiaodong gold deposits was concentrated in Mesozoic. Metallogenic chronology and geological-geochemical data indicate that there are two periods of gold mineralizations occurred in 130-110 Ma and 90-80 Ma respectively in Jiaodong ore cluster. The gold deposit cluster results from the superimposition of the polygenetic mineralization, and further study is needed to investigate the formation and evolution of the Mesozoic complex metallogenic system.

  13. The Impacts of Ultraviolet Radiation Feedback on galaxies during the Epoch of Reionisation

    CERN Document Server

    Hasegawa, Kenji

    2012-01-01

    We explore the impacts of ultraviolet (UV) radiation feedback on galaxies during the epoch of reionisation by cosmological simulations in which hydrodynamics and the transfer of the H and He ionising photons are consistently coupled. Moreover we take into account H_2 non-equilibrium chemistry, including photo-dissociation. The most striking feature of the simulations is a high spatial resolution for the radiative transfer (RT) calculation which enables us to start considering not only external UV feedback processes but also internal UV feedback processes in each galaxy. We find that the star formation is significantly suppressed due to the internal UV and supernova (SN) feedback. In low mass galaxies with M<10^9Msun, a large amount of gas is evacuated by photo-evaporation as previous studies have shown, which results in the suppression of star formation. Surprisingly, star formation in massive halos is also strongly suppressed despite the fact that these halos hardly lose any gas by photo-evaporation. The ...

  14. Neural correlates of rules and conflict in medial prefrontal cortex during decision and feedback epochs.

    Science.gov (United States)

    Bissonette, Gregory B; Roesch, Matthew R

    2015-01-01

    The ability to properly adjust behavioral responses to cues in a changing environment is crucial for survival. Activity in the medial Prefrontal Cortex (mPFC) is thought to both represent rules to guide behavior as well as detect and resolve conflicts between rules in changing contingencies. However, while lesion and pharmacological studies have supported a crucial role for mPFC in this type of set-shifting, an understanding of how mPFC represents current rules or detects and resolves conflict between different rules is unclear. Here, we directly address the role of rat mPFC in shifting rule based behavioral strategies using a novel behavioral task designed to tease apart neural signatures of rules, conflict and direction. We demonstrate that activity of single neurons in rat mPFC represent distinct rules. Further, we show increased firing on high conflict trials in a separate population of mPFC neurons. Reduced firing in both populations of neurons was associated with poor performance. Moreover, activity in both populations increased and decreased firing during the outcome epoch when reward was and was not delivered on correct and incorrect trials, respectively. In addition, outcome firing was modulated by the current rule and the degree of conflict associated with the previous decision. These results promote a greater understanding of the role that mPFC plays in switching between rules, signaling both rule and conflict to promote improved behavioral performance.

  15. Contamination of the Epoch of Reionization power spectrum in the presence of foregrounds

    CERN Document Server

    Sims, Peter H; Alexander, Paul; Carilli, Chris L

    2016-01-01

    We construct foreground simulations comprising spatially correlated extragalactic and diffuse Galactic emission components and calculate the `intrinsic' (instrument-free) two-dimensional spatial power spectrum and the cylindrically and spherically averaged three-dimensional k-space power spectra of the Epoch of Reionization (EoR) and our foreground simulations using a Bayesian power spectral estimation framework. This leads us to identify a model dependent region of optimal signal estimation for our foreground and EoR models, within which the spatial power in the EoR signal relative to foregrounds is maximised. We identify a target field dependent region, in k-space, of intrinsic foreground power spectral contamination at low k_perp and k_parallel and a transition to a relatively foreground-free intrinsic EoR window in the complement to this region. The contaminated region of k-space demonstrates that simultaneous estimation of the EoR and foregrounds is important for obtaining statistically robust estimates ...

  16. Diverse properties of interstellar medium embedding gamma-ray bursts at the epoch of reionization

    Energy Technology Data Exchange (ETDEWEB)

    Cen, Renyue; Kimm, Taysun, E-mail: cen@astro.princeton.edu [Princeton University Observatory, Princeton, NJ 08544 (United States)

    2014-10-10

    Analysis is performed on ultra-high-resolution large-scale cosmological radiation-hydrodynamic simulations to quantify, for the first time, the physical environment of long-duration gamma-ray bursts (GRBs) at the epoch of reionization. We find that, on parsec scales, 13% of GRBs remain in high-density (≥10{sup 4} cm{sup –3}) low-temperature star-forming regions, whereas 87% of GRBs occur in low-density (∼10{sup –2.5} cm{sup –3}) high-temperature regions heated by supernovae. More importantly, the spectral properties of GRB afterglows, such as the neutral hydrogen column density, total hydrogen column density, dust column density, gas temperature, and metallicity of intervening absorbers, vary strongly from sight line to sight line. Although our model explains extant limited observationally inferred values with respect to circumburst density, metallicity, column density, and dust properties, a substantially larger sample of high-z GRB afterglows would be required to facilitate a statistically solid test of the model. Our findings indicate that any attempt to infer the physical properties (such as metallicity) of the interstellar medium (ISM) of the host galaxy based on a very small number (usually one) of sight lines would be precarious. Utilizing high-z GRBs to probe the ISM and intergalactic medium should be undertaken properly, taking into consideration the physical diversities of the ISM.

  17. GNSS Single Frequency, Single Epoch Reliable Attitude Determination Method with Baseline Vector Constraint.

    Science.gov (United States)

    Gong, Ang; Zhao, Xiubin; Pang, Chunlei; Duan, Rong; Wang, Yong

    2015-12-02

    For Global Navigation Satellite System (GNSS) single frequency, single epoch attitude determination, this paper proposes a new reliable method with baseline vector constraint. First, prior knowledge of baseline length, heading, and pitch obtained from other navigation equipment or sensors are used to reconstruct objective function rigorously. Then, searching strategy is improved. It substitutes gradually Enlarged ellipsoidal search space for non-ellipsoidal search space to ensure correct ambiguity candidates are within it and make the searching process directly be carried out by least squares ambiguity decorrelation algorithm (LAMBDA) method. For all vector candidates, some ones are further eliminated by derived approximate inequality, which accelerates the searching process. Experimental results show that compared to traditional method with only baseline length constraint, this new method can utilize a priori baseline three-dimensional knowledge to fix ambiguity reliably and achieve a high success rate. Experimental tests also verify it is not very sensitive to baseline vector error and can perform robustly when angular error is not great.

  18. Constraining stellar assembly and AGN feedback at the peak epoch of star formation

    CERN Document Server

    Kimm, Taysun; Devriendt, Julien; Cohen, Seth; Windhorst, Rogier; Dubois, Yohan; Slyz, Adrianne; Hathi, Nimish; Ryan, Russell; O'Connell, Robert; Dopita, Michael; Silk, Joseph

    2012-01-01

    We study stellar assembly and feedback from active galactic nuclei (AGN) around the epoch of peak star formation (1

  19. Superposed epoch analysis of the ionospheric convection evolution during substorms: onset latitude dependence

    Directory of Open Access Journals (Sweden)

    A. Grocott

    2009-02-01

    Full Text Available Using data from the Super Dual Auroral Radar Network (SuperDARN we investigate the ionospheric convection response to magnetospheric substorms. Substorms were identified using the Far Ultraviolet (FUV instrument on board the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE spacecraft, and were then binned according to the magnetic latitude of their onset. A superposed epoch analysis of the ionospheric convection patterns for each onset-latitude bin was then performed using radar data for the interval 60 min before onset to 90 min after. It is found that lower onset-latitude substorms are associated with generally more enhanced convection than the higher latitude substorms, although they suffer from a significant localised reduction of the flow in the midnight sector during the expansion phase. Higher-latitude substorms are associated with a significant and rapid increase in the nightside convection following substorm onset, with all onset-latitude bins showing an enhancement over onset values by ~60 min into the expansion phase. A rudimentary inspection of the concurrent auroral evolution suggests that the duration of the flow reduction following substorm onset is dependent on the strength and duration of the expansion phase aurora and its associated conductivity enhancement.

  20. A new probe of magnetic fields in the pre-reionization epoch: I. Formalism

    CERN Document Server

    Venumadhav, Tejaswi; Gluscevic, Vera; Mishra, Abhilash; Hirata, Christopher M

    2014-01-01

    We propose a method of measuring extremely weak magnetic fields in the inter galactic medium prior to and during the epoch of cosmic reionization. The method utilizes the Larmor precession of spin-polarized neutral hydrogen in the triplet state of the hyperfine transition. The resulting change in the brightness temperature fluctuations encodes information about the magnetic field the atoms are immersed in. The method is most suited to probing fields that are coherent on large scales. Due to the long lifetime of the triplet state of the 21-cm transition, this technique is naturally sensitive to extremely weak field strengths, of order $10^{-19}$ G (or $10^{-21}$ G if scaled to the present day). Therefore, this might open up the possibility of probing primordial magnetic fields just prior to reionization. Moreover, such measurements are unaffected by later magnetic fields since 21-cm observations preserve redshift information. If the magnetic fields are much stronger, it is still possible to recover information...

  1. The SuperCosmos South Galactic Cap multi-colour/epoch digitised survey - Online!

    Science.gov (United States)

    Hambly, N.; Read, M.

    We describe the first release of data from the SuperCOSMOS Sky Survey programme, the South Galactic Cap survey. This consists of a 3 colour (BRI), one colour (R) at 2 epochs, digital sky survey based on high Galactic latitude (|b|>60o) Schmidt survey plates covering ~5000 square degrees - it is the first digitised sky survey to include both colours and proper motions. Positions are tied to the International Co-ordinate Reference Frame via the Tycho-ACT catalogue and are externally accurate to ~0.3 arcsec; proper motions (also zero-pointed on the extragalactic frame) are typically accurate to ~10 mas yr-1. Photometry in BRI is accurate to ~0.2m and is tied to external CCD zeropoints with field-to-field zeropoint errors minimised using field overlap regions. We describe a simple database interrogation example and show the results. Finally, we describe the future plans for expanding the survey to cover the full southern sky. For full details access the survey homepage on http://www-wfau.roe.ac.uk/sss/.

  2. The Epoch of Reionization in the R_h=ct Universe

    CERN Document Server

    Melia, Fulvio

    2015-01-01

    The measured properties of the epoch of reionization (EoR) show that reionization probably began around z ~ 12-15 and ended by z=6. In addition, a careful analysis of the fluctuations in the cosmic microwave background indicate a scattering optical depth tau ~ 0.066+/-0.012 through the EoR. In the context of LCDM, galaxies at intermediate redshifts and dwarf galaxies at higher redshifts now appear to be the principal sources of UV ionizing radiation, but only for an inferred (ionizing) escape fraction f_ion ~ 0.2, which is in tension with other observations that suggest a value as small as ~ 0.05. In this paper, we examine how reionization might have progressed in the alternative Friedmann-Robertson Walker cosmology known as the R_h=ct Universe, and determine the value of f_ion required with this different rate of expansion. We find that R_h=ct accounts quite well for the currently known properties of the EoR, as long as its fractional baryon density falls within the reasonable range 0.026 < Omega_b < 0...

  3. The impact of point source subtraction residuals on 21 cm Epoch of Reionization estimation

    CERN Document Server

    Trott, Cathryn M; Tingay, Steven J

    2012-01-01

    Precise subtraction of foreground sources is crucial for detecting and estimating 21cm HI signals from the Epoch of Reionization (EoR). We quantify how imperfect point source subtraction due to limitations of the measurement dataset yields structured residual signal in the dataset. We use the Cramer-Rao lower bound, as a metric for quantifying the precision with which a parameter may be measured, to estimate the residual signal in a visibility dataset due to imperfect point source subtraction. We then propagate these residuals into two metrics of interest for 21cm EoR experiments - the angular and two-dimensional power spectrum - using a combination of full analytic covariant derivation, analytic variant derivation, and covariant Monte Carlo simulations. This methodology differs from previous work in two ways: (1) it uses information theory to set the point source position error, rather than assuming a global root-mean-square error, and (2) it describes a method for propagating the errors analytically, thereb...

  4. First Results on the Epoch of Reionization from First Light with SARAS 2

    Science.gov (United States)

    Singh, Saurabh; Subrahmanyan, Ravi; Udaya Shankar, N.; Sathyanarayana Rao, Mayuri; Fialkov, Anastasia; Cohen, Aviad; Barkana, Rennan; Girish, B. S.; Raghunathan, A.; Somashekar, R.; Srivani, K. S.

    2017-08-01

    Long-wavelength spectral distortions in the cosmic microwave background arising from the 21 cm transition in neutral hydrogen are a key probe of the Cosmic Dawn and the Epoch of Reionization. These features may reveal the nature of the first stars and ultra-faint galaxies that transformed the spin temperature and ionization state of the primordial gas. SARAS 2 is a spectral radiometer purposely designed for the precision measurement of these monopole or all-sky global 21 cm spectral distortions. We use 63 hr nighttime observations of the radio background in the frequency band 110-200 MHz, with the radiometer deployed at the Timbaktu Collective in Southern India, to derive likelihoods for plausible redshifted 21 cm signals predicted by theoretical models. First light with SARAS 2 disfavors the class of models that feature weak X-ray heating (with {f}X≤slant 0.1) and rapid reionization (with peak \\tfrac{{{dT}}b}{{dz}}≥slant 120 mK per unit redshift interval).

  5. The Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey II: The First Four Epochs

    CERN Document Server

    Lovell, J E J; Macquart, J-P; Jauncey, D L; Bignall, H E; Kedziora-Chudczer, L; Ojha, R; Pursimo, T; Dutka, M; Senkbeil, C; Shabala, S

    2008-01-01

    We report on the variability of 443 flat spectrum, compact radio sources monitored using the VLA for 3 days in 4 epochs at ~ 4 month intervals at 5 GHz as part of the Micro-Arcsecond Scintillation-Induced Variability (MASIV) survey. Over half of these sources exhibited 2-10% rms variations on timescales over 2 days. We analyzed the variations by two independent methods, and find that the rms variability amplitudes of the sources correlate with the emission measure in the ionized Interstellar Medium along their respective lines of sight. We thus link the variations with interstellar scintillation of components of these sources, with some (unknown) fraction of the total flux density contained within a compact region of angular diameter in the range 10-50 micro-arcseconds. We also find that the variations decrease for high mean flux density sources and, most importantly, for high redshift sources. The decrease in variability is probably due either to an increase in the apparent diameter of the source, or a decre...

  6. Multi-Epoch Observations of the Redwing Excess in the Spectrum of 3C279

    CERN Document Server

    Punsly, Brian

    2012-01-01

    It has been previously determined that there is a highly significant correlation between the spectral index from 10 GHz to 1350 $\\AA$ and the amount of excess luminosity in the red wing of quasar CIV $\\lambda$1549 broad emission lines (BELs). Ostensibly, the prominence of the red excess is associated with the radio jet emission mechanism and is most pronounced for lines of sight close to the jet axis. Studying the scant significant differences in the UV spectra of radio loud and radio quiet quasars might provide vital clues to the origin of the unknown process that creates powerful relativistic jets that appear in only about ten percent of quasars. In this study, the phenomenon is explored with multi-epoch observations of the MgII $\\lambda$2798 broad line in 3C 279 which has one of the largest known redwing excesses in a quasar spectrum. The amount of excess that is detected appears to be independent of all directly observed optical continuum, radio or submm properties (fluxes or polarizations). The only tren...

  7. Thermokarst, mantling and Late Amazonian Epoch periglacial-revisions in the Argyre region, Mars

    Science.gov (United States)

    Soare, R. J.; Baoini, D.; Conway, S. J.; Dohm, J. M.; Kargel, J. S.

    2015-10-01

    Thermokarst, mantling and Late Amazonian Epoch periglacial-revisions in the Argyre region, Mars R.J. Soare(1), D. Baioni(2), S.J. Conway (3), J.M. Dohm(4)and J.S. Kargel (5)(1) Geography Department, Dawson College, Montreal, Canada H3Z 1A4 rsoare@dawsoncollege.qc.ca.(2) Dipartimento di Scienze della Terra,della Vita e Ambiente, Università di Urbino "Carlo Bo", Campus SOGESTA, 61029 Urbino (PU) Italy. (3) Department of Physical Sciences, Open University, Milton Keynes, United Kingdom, MK7 6AA. (4) The University Museum, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-, Japan.(5) Department of Hydrology & Water Resources, University of Arizona, Tucson, Arizona, USA 85719.1.Introduction Metre to decametre-deep depressions that are rimless, relatively flat-floored, polygonised and scallop-shaped have been widely observed in Utopia Planitia (UP) [e.g. 1-5] and Malea Planum (MP) [6-8]. Although there is some debate about whether the depressions formed by means of sublimation or evaporation, it is commonly believed that the terrain in which the depressions occur is ice-rich.Moreover, most workers assume that this "ice-richness" is derived of a bi-hemispheric, latitudinally-dependent and atmospherically-precipitated mantle that is metres thick [2,4,6-10].

  8. Non-parametric foreground subtraction for 21cm epoch of reionization experiments

    CERN Document Server

    Harker, Geraint; Bernardi, Gianni; Brentjens, Michiel A; De Bruyn, A G; Ciardi, Benedetta; Jelic, Vibor; Koopmans, Leon V E; Labropoulos, Panagiotis; Mellema, Garrelt; Offringa, Andre; Pandey, V N; Schaye, Joop; Thomas, Rajat M; Yatawatta, Sarod

    2009-01-01

    An obstacle to the detection of redshifted 21cm emission from the epoch of reionization (EoR) is the presence of foregrounds which exceed the cosmological signal in intensity by orders of magnitude. We argue that in principle it would be better to fit the foregrounds non-parametrically - allowing the data to determine their shape - rather than selecting some functional form in advance and then fitting its parameters. Non-parametric fits often suffer from other problems, however. We discuss these before suggesting a non-parametric method, Wp smoothing, which seems to avoid some of them. After outlining the principles of Wp smoothing we describe an algorithm used to implement it. We then apply Wp smoothing to a synthetic data cube for the LOFAR EoR experiment. The performance of Wp smoothing, measured by the extent to which it is able to recover the variance of the cosmological signal and to which it avoids leakage of power from the foregrounds, is compared to that of a parametric fit, and to another non-parame...

  9. About Basic Epochs of Crust Formation and Kimberlite Magmatism in Connection with Diamond Prospecting Works

    Directory of Open Access Journals (Sweden)

    N. N. Zinchuk

    2014-06-01

    Full Text Available Results of comprehensive analysis of large amount of worldwide and regional geological information allowed suggesting necessity of more intensive research of massive crust formation and diamondiferous magmatism epochs, which were paid little attention to. Presently available highly scattered information allows distinguishing two megastages in formation of the Siberian platform diamondiferousness. The early stage includes the time from Archean to Riphean or from diamonds formation in the mantle to its first appearance at the surface conditions. Polycentrism, localization at peripheral parts of the platform, as well as diversity of transporters are characteristic for this megastage. The second megastage (Early Paleozoic-Eocene differs from the first one by spatial arrangement of occurrences, monocentrism, and prevalence of kimberlite diatremes. During planning and carrying out the diamonds prospecting works on perspective territories of the platform, it is necessary to study not only Middle-Paleozoic productive collectors, but also more ancient (Preсambrian and Lower Paleozoic and young (Mesozoic strata as well, performing detailed complex analysis of  rock composition (especially the key layers and basal horizons.

  10. Warm tropical sea surface temperatures in the Late Cretaceous and Eocene epochs.

    Science.gov (United States)

    Pearson, P N; Ditchfield, P W; Singano, J; Harcourt-Brown, K G; Nicholas, C J; Olsson, R K; Shackleton, N J; Hall, M A

    2001-10-04

    Climate models with increased levels of carbon dioxide predict that global warming causes heating in the tropics, but investigations of ancient climates based on palaeodata have generally indicated cool tropical temperatures during supposed greenhouse episodes. For example, in the Late Cretaceous and Eocene epochs there is abundant geological evidence for warm, mostly ice-free poles, but tropical sea surface temperatures are generally estimated to be only 15-23 degrees C, based on oxygen isotope palaeothermometry of surface-dwelling planktonic foraminifer shells. Here we question the validity of most such data on the grounds of poor preservation and diagenetic alteration. We present new data from exceptionally well preserved foraminifer shells extracted from impermeable clay-rich sediments, which indicate that for the intervals studied, tropical sea surface temperatures were at least 28-32 degrees C. These warm temperatures are more in line with our understanding of the geographical distributions of temperature-sensitive fossil organisms and the results of climate models with increased CO2 levels.

  11. A LYMAN BREAK GALAXY IN THE EPOCH OF REIONIZATION FROM HUBBLE SPACE TELESCOPE GRISM SPECTROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Rhoads, James E.; Malhotra, Sangeeta; Cohen, Seth; Zheng Zhenya [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Dickinson, Mark [National Optical Astronomy Observatory, Tucson, AZ (United States); Pirzkal, Norbert; Grogin, Norman; Koekemoer, Anton; Peth, Michael A. [Space Telescope Science Institute, Baltimore, MD (United States); Spinrad, Hyron [University of California, Berkeley, CA (United States); Reddy, Naveen [University of California, Riverside, CA (United States); Hathi, Nimish [Observatories of the Carnegie Institution of Washington, Pasadena, CA (United States); Budavari, Tamas [Johns Hopkins University, Baltimore, MD (United States); Ferreras, Ignacio [Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom); Gardner, Jonathan P. [NASA Goddard Space Flight Center, Astrophysics Science Division, Observational Cosmology Laboratory, Code 665, Greenbelt, MD 20771 (United States); Gronwall, Caryl [Department of Astronomy and Astrophysics, and Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802 (United States); Haiman, Zoltan [Columbia University, New York, NY (United States); Kuemmel, Martin [Universitaets-Sternwarte Muenchen, Scheinerstr. 1, D-81679 Muenchen (Germany); Meurer, Gerhardt, E-mail: James.Rhoads@asu.edu [International Centre for Radio Astronomy Research, University of Western Australia, M468, 35 Stirling Highway, Crawley, WA 6009 (Australia); and others

    2013-08-10

    We present observations of a luminous galaxy at z = 6.573-the end of the reionization epoch-which has been spectroscopically confirmed twice. The first spectroscopic confirmation comes from slitless Hubble Space Telescope Advanced Camera for Surveys grism spectra from the PEARS survey (Probing Evolution And Reionization Spectroscopically), which show a dramatic continuum break in the spectrum at rest frame 1216 A. The second confirmation is done with Keck + DEIMOS. The continuum is not clearly detected with ground-based spectra, but high wavelength resolution enables the Ly{alpha} emission line profile to be determined. We compare the line profile to composite line profiles at z = 4.5. The Ly{alpha} line profile shows no signature of a damping wing attenuation, confirming that the intergalactic gas is ionized at z = 6.57. Spectra of Lyman breaks at yet higher redshifts will be possible using comparably deep observations with IR-sensitive grisms, even at redshifts where Ly{alpha} is too attenuated by the neutral intergalactic medium to be detectable using traditional spectroscopy from the ground.

  12. The EPOCH Project: I. Periodic Variable Stars in the EROS-2 LMC Database

    CERN Document Server

    Kim, Dae-Won; Bailer-Jones, Coryn A L; Byun, Yong-Ik; Chang, Seo-Won; Marquette, Jean-Baptiste; Shin, Min-Su

    2014-01-01

    The EPOCH (EROS-2 periodic variable star classification using machine learning) project aims to detect periodic variable stars in the EROS-2 light curve database. In this paper, we present the first result of the classification of periodic variable stars in the EROS-2 LMC database. In order to classify these variables, we first build a training set by compiling known variables in the Large Magellanic Could area from the OGLE and MACHO surveys. We crossmatch these variables with the EROS-2 sources and extract 22 variability features from 28,392 light curves of the corresponding EROS-2 sources. We then use Random Forests to classify the EROS-2 sources in the training set. We design the model to separate not only $\\delta$ Scuti stars, RR Lyraes, Cepheids, eclipsing binaries and long-period variables, the "superclasses", but also their subclasses, such as RRab, RRc, RRd and RRe for RR Lyraes, and similarly for the other variable types. The model trained using only the superclasses shows 99% recall and precision w...

  13. Studying neutral hydrogen structures during the epoch of reionization using fractal dimensions

    CERN Document Server

    Bandyopadhyay, Bidisha; Seshadri, T R

    2016-01-01

    Fractal dimensions can be used to characterize the clustering and lacunarities in density distributions. We use generalized fractal dimensions to study the neutral hydrogen distribution (HI) during the epoch of reionization. Using a semi-numeric model of ionized bubbles to generate the HI field, we calculate the fractal dimensions for length scales $\\sim 10 h^{-1}$ cMpc. We find that the HI field displays significant multifractal behaviour and is not consistent with homogeneity at these scales when the mass averaged neutral fraction $\\bar{x}_{\\rm HI}^M \\gtrsim 0.5$. This multifractal nature is driven entirely by the shapes and distribution of the ionized regions. The sensitivity of the fractal dimension to the neutral fraction implies that it can be used for constraining reionization history. We find that the fractal dimension is relatively less sensitive to the value of the minimum mass of ionizing haloes when it is in the range $\\sim 10^9 - 10^{10} h^{-1} M_{\\odot}$. Interestingly, the fractal dimension is ...

  14. Dynamics of large-scale solar-wind streams obtained by the double superposed epoch analysis

    CERN Document Server

    Yermolaev, Yu I; Nikolaeva, N S; Yermolaev, M Yu

    2015-01-01

    Using the OMNI data for period 1976-2000 we investigate the temporal profiles of 20 plasma and field parameters in the disturbed large-scale types of solar wind (SW): CIR, ICME (both MC and Ejecta) and Sheath as well as the interplanetary shock (IS). To take into account the different durations of SW types, we use the double superposed epoch analysis (DSEA) method: re-scaling the duration of the interval for all types in such a manner that, respectively, beginning and end for all intervals of selected type coincide. As the analyzed SW types can interact with each other and change parameters as a result of such interaction, we investigate separately 8 sequences of SW types: (1) CIR, (2) IS/CIR, (3) Ejecta, (4) Sheath/Ejecta, (5) IS/Sheath/Ejecta, (6) MC, (7) Sheath/MC, and (8) IS/Sheath/MC. The main conclusion is that the behavior of parameters in Sheath and in CIR are very similar both qualitatively and quantitatively. Both the high-speed stream (HSS) and the fast ICME play a role of pistons which push the pl...

  15. Polarization leakage in Epoch of Reionization windows: I. LOFAR observations of the 3C196 field

    CERN Document Server

    Asad, Khan M B; Jelić, Vibor; Pandey, V N; Ghosh, Abhik; Abdalla, F B; Bernardi, G; Brentjens, M A; de Bruyn, A G; Bus, S; Ciardi, B; Chapman, E; Daiboo, S; Fernandez, E R; Harker, G; Iliev, I T; Jensen, H; Martinez-Rubi, O; Mellema, G; Mevius, M; Offringa, A R; Patil, A H; Schaye, J; Thomas, R M; van der Tol, S; Vedantham, H K; Yatawatta, S; Zaroubi, S

    2015-01-01

    Detection of the cosmological 21-cm signal coming from the epoch of reionization (EoR) is challenging in the presence of astrophysical foregrounds and direction (in)dependent systematic errors of the instrument. Even after removing the foregrounds, the residual Stokes I maps contain, in addition to the system noise, the polarized foreground leaked from Stokes Q, U due to systematic and random errors which can mimic the EoR signal. Here we discuss the systematic errors, especially the primary beam, of LOFAR and present realistic simulations of the leakages caused by them. We made a Stokes Q, U sky model of the Galactic diffuse emission based on the LOFAR observations of the 3C196 field, simulated the full-Stokes visibilities that would be produced by LOFAR in the presence of its nominal model beam, created RM-cubes and the cylindrically and spherically averaged 3D power spectra (PS), and compared them with the PS of a simulated EoR signal. From the spherical PS, we found that at 134-166 MHz, within the central...

  16. Methodological proposal for the jotted issue of the first epoch of the Hero magazine.

    Directory of Open Access Journals (Sweden)

    Maité García Díaz

    2013-07-01

    Full Text Available During the neocolonial republic emerges in Sancti Spiritus a very significative magazine of artistic, literary and scientific sketch: Hero, founded by Jacinto Gomer Fernández-Morera and Anastacio Fernández-Morera del Castillo, it first appeared on December 20th 1907. This issue constitutes a vivid reflect of the commercial, literary, cultural, scientific and historic panorama and above all, of the life of the middle and high class in Sancti Spiritus at the beginning of the XX century. The need to divulge the advantage the texts of Hero constitute for the high school and university students, also to humanistic profile graduates and others, such as investigators, evidenced the need to carry out an investigation that pursued such purposes. That’s why the methodological proposal for the jotted issue of the first epoch of the Hero magazine (1907-1908 takes place, composed by 38 publications, departing from the fundamental theorizations about the jotted issue of the presentation of the methodological proposal on behalf of updating these publication texts for its potential readers.

  17. Performance improvement of GPS single frequency, single epoch attitude determination with poor satellite visibility

    Science.gov (United States)

    Chen, Wantong; Sun, Xingli

    2016-07-01

    Similar to global positioning system (GPS) positioning in urban canyons, a fast and successful attitude determination with limited satellite visibility is very significant. For land vehicles, the possible attitude candidates can be treated as a spherical zone with the center at the reference antenna and the baseline as the radius. This provides an important constraint, which can be exploited to improve the reliability of GPS single frequency and single epoch attitude determination in the case of poor satellite reception. First, we fully integrate the spherical zone constraint into the estimation procedure of ambiguity resolution, but not in the validation procedure. Combining both the coordinate domain search and the ambiguity domain search, allows development of a global minimizer of the fixed ambiguity objective function. This scheme also improves the precision of the float ambiguity solution, thus avoiding the problem of search halting. The performance of the new ambiguity resolution method was analyzed by means of several experimental tests, using simulated as well as actual GPS data in urban environments. The experimental results showed that this new, proposed method can utilize a priori spherical zone knowledge to improve the reliability of ambiguity resolution in difficult environments.

  18. Revealing the accretion disc corona in Mrk 335 with multi-epoch X-ray spectroscopy

    CERN Document Server

    Keek, L

    2015-01-01

    Active galactic nuclei host an accretion disc with an X-ray producing corona around a supermassive black hole. In bright sources, such as the Seyfert 1 galaxy Mrk 335, reflection of the coronal emission off the accretion disc has been observed. Reflection produces spectral features such as an Fe K$\\alpha$ emission line, which allow for properties of the inner accretion disc and the corona to be constrained. We perform a multi-epoch spectral analysis of all XMM-Newton, Suzaku, and NuSTAR observations of Mrk 335, and we optimize our fitting procedure to unveil correlations between the Eddington ratio and the spectral parameters. We find that the disc's ionization parameter correlates strongly with the Eddington ratio: the inner disc is more strongly ionized at higher flux. The slope of the correlation is less steep than previously predicted. Furthermore, the cut-off of the power-law spectrum increases in energy with the Eddington ratio, whereas the reflection fraction exhibits a decrease. We interpret this beha...

  19. Second Epoch Hubble Space Telescope Observations of Kepler's Supernova Remnant: The Proper Motions of Balmer Filaments

    CERN Document Server

    Sankrit, Ravi; Blair, William P; Long, Knox S; Williams, Brian J; Borkowski, Kazimierz J; Patnaude, Daniel J; Reynolds, Stephen P

    2015-01-01

    We report on the proper motions of Balmer-dominated filaments in Kepler's supernova remnant using high resolution images obtained with the Hubble Space Telescope at two epochs separated by about 10 years. We use the improved proper motion measurements and revised values of shock velocities to derive a distance to Kepler of 5.1 [+0.8, -0.7] kpc. The main shock around the northern rim of the remnant has a typical speed of 1690 km/s and is encountering material with densities of about 8 cm^-3. We find evidence for the variation of shock properties over small spatial scales, including differences in the driving pressures as the shock wraps around a curved cloud surface. We find that the Balmer filaments ahead of the ejecta knot on the northwest boundary of the remnant are becoming fainter and more diffuse. We also find that the Balmer filaments associated with circumstellar material in the interior regions of the remnant are due to shocks with significantly lower velocities and that the brightness variations amon...

  20. The Cosmic Dawn and Epoch of Reionization with the Square Kilometre Array

    CERN Document Server

    Koopmans, L V E; Mellema, G; Abdalla, F; Aguirre, J; Ahn, K; Barkana, R; van Bemmel, I; Bernardi, G; Bonaldi, A; Briggs, F; de Bruyn, A G; Chang, T C; Chapman, E; Chen, X; Ciardi, B; Datta, K K; Dayal, P; Ferrara, A; Fialkov, A; Fiore, F; Ichiki, K; Illiev, I T; Inoue, S; Jelić, V; Jones, M; Lazio, J; Maio, U; Majumdar, S; Mack, K J; Mesinger, A; Morales, M F; Parsons, A; Pen, U -L; Santos, M; Schneider, R; Semelin, B; de Souza, R S; Subrahmanyan, R; Takeuchi, T; Trott, C; Vedantham, H; Wagg, J; Webster, R; Wyithe, S

    2015-01-01

    Concerted effort is currently ongoing to open up the Epoch of Reionization (EoR) ($z\\sim$15-6) for studies with IR and radio telescopes. Whereas IR detections have been made of sources (Lyman-$\\alpha$ emitters, quasars and drop-outs) in this redshift regime in relatively small fields of view, no direct detection of neutral hydrogen, via the redshifted 21-cm line, has yet been established. Such a direct detection is expected in the coming years, with ongoing surveys, and could open up the entire universe from $z\\sim$6-200 for astrophysical and cosmological studies, opening not only the EoR, but also its preceding Cosmic Dawn ($z\\sim$30-15) and possibly even the later phases of the Dark Ages ($z\\sim$200-30). All currently ongoing experiments attempt statistical detections of the 21-cm signal during the EoR, with limited signal-to-noise. Direct imaging, except maybe on the largest (degree) scales at lower redshifts, as well as higher redshifts will remain out of reach. The Square Kilometre Array(SKA) will revolu...

  1. GNSS Single Frequency, Single Epoch Reliable Attitude Determination Method with Baseline Vector Constraint

    Directory of Open Access Journals (Sweden)

    Ang Gong

    2015-12-01

    Full Text Available For Global Navigation Satellite System (GNSS single frequency, single epoch attitude determination, this paper proposes a new reliable method with baseline vector constraint. First, prior knowledge of baseline length, heading, and pitch obtained from other navigation equipment or sensors are used to reconstruct objective function rigorously. Then, searching strategy is improved. It substitutes gradually Enlarged ellipsoidal search space for non-ellipsoidal search space to ensure correct ambiguity candidates are within it and make the searching process directly be carried out by least squares ambiguity decorrelation algorithm (LAMBDA method. For all vector candidates, some ones are further eliminated by derived approximate inequality, which accelerates the searching process. Experimental results show that compared to traditional method with only baseline length constraint, this new method can utilize a priori baseline three-dimensional knowledge to fix ambiguity reliably and achieve a high success rate. Experimental tests also verify it is not very sensitive to baseline vector error and can perform robustly when angular error is not great.

  2. Identification of RR Lyrae Variables in SDSS from Single-Epoch Photometric and Spectroscopic Observations

    CERN Document Server

    Wilhelm, Ronald; Beers, Timothy C; Sesar, Branimir; Prieto, Carlos Alende; Carrell, Kenneth W; Lee, Young Sun; Yanny, Brian; Rockosi, Constance M; De Lee, Nathan; Armstrong, Gwen Hansford; Torrence, Stephen J

    2007-01-01

    We describe a new RR Lyrae identification technique based on out-of-phase single-epoch photometric and spectroscopic observations contained in SDSS Data Release 6 (DR-6). This technique detects variability by exploiting the large disparity between the g-r color and the strength of the hydrogen Balmer lines when the two observations are made at random phases. Comparison with a large sample of known variables in the SDSS equatorial stripe (Stripe 82) shows that the discovery efficiency for our technique is ~85%. Analysis of stars with multiple spectroscopic observations suggests a similar efficiency throughout the entire DR-6 sample. We also develop a technique to estimate the average g apparent magnitude (over the pulsation cycle) for individual RR Lyrae stars, using the for the entire sample and measured colors for each star. The resulting distances are found to have precisions of ~14%. Finally, we explore the properties of our DR-6 sample of N = 1087 variables, and recover portions of the Sagittarius Northe...

  3. Japanese Cosmic Dawn/Epoch of Reionization Science with the Square Kilometre Array

    CERN Document Server

    Hasegawa, Kenji; Ichiki, Kiyotomo; Inoue, Akio K; Inoue, Susumu; Ishiyama, Tomoaki; Shimabukuro, Hayato; Takahashi, Keitaro; Tashiro, Hiroyuki; Yajima, Hidenobu; Yokoyama, Shu-ichiro; Yoshikawa, Kohji; Yoshiura, Shintaro

    2016-01-01

    Cosmic reionization is known to be a major phase transition of the gas in the Universe. Since astronomical objects formed in the early Universe, such as the first stars, galaxies and black holes, are expected to have caused cosmic reionization, the formation history and properties of such objects are closely related to the reionization process. In spite of the importance of exploring reionization, our understandings regarding reionization is not sufficient yet. Square Kilometre Array (SKA) is a next-generation large telescope that will be operated in the next decade. Although several programs of next-generation telescopes are currently scheduled, the SKA will be the unique telescope with a potential to directly observe neutral hydrogen up to z~30, and provide us with valuable information on the Cosmic Dawn (CD) and the Epoch of Reionization (EoR). The early science with the SKA will start in a few years; it is thus the time for us to elaborate a strategy for CD/EoR Science with the SKA. The purpose of this do...

  4. Foreground contamination in Ly-alpha intensity mapping during the epoch of reionization

    CERN Document Server

    Gong, Yan; Cooray, Asantha; Santos, Mario G

    2013-01-01

    The intensity mapping of Ly-alpha emission during the epoch of reionization (EoR) will be contaminated by foreground emission lines from lower redshifts. We calculate the mean intensity and power spectrum of Ly-alpha emission at z~7, and estimate the uncertainties according to the relevant astrophysical processes. We find that the low-redshift emission lines from 6563 A H-alpha, 5007 A [OIII] and 3727 A [OII] will be the strong contaminants on the observed Ly-alpha power spectrum. We make use of both the star formation rate (SFR) and luminosity functions (LF) to estimate the mean intensity and power spectra of the three foreground lines at z~0.5 for H-alpha, z~0.9 for [OIII] and z~1.6 for [OII], as they will contaminate the Ly-alpha emission at z~7. The [OII] line is found to be the strongest. We analyze the masking of the bright survey pixels with a foreground line above some line intensity threshold as a way to reduce the contamination in the intensity mapping survey. We find that the foreground contaminati...

  5. Constraints on the Star Formation Efficiency of Galaxies During the Epoch of Reionization

    CERN Document Server

    Sun, Guochao

    2015-01-01

    Reionization is thought to have occurred in the redshift range of $6 6$ that matches the measured galaxy luminosity functions at these redshifts. We find that $f_*$ peaks at $\\sim 10\\%$ at halo masses $M \\sim 10^{11}$--$10^{12}$~M$_\\odot$, in qualitative agreement with its behavior at lower redshifts. We then investigate the cosmic star formation histories and the corresponding models of reionization for a range of extrapolations to small halo masses. We compare these to a variety of observations, using them to further constrain the characteristics of the galaxy populations. Our approach provides an empirically-calibrated, physically-motivated model for the properties of star-forming galaxies sourcing the epoch of reionization. In the case where star formation in low-mass halos is maximally efficient, an average escape fraction $\\sim0.1$ can reproduce the optical depth reported by Planck, whereas inefficient star formation in these halos requires either about twice as many UV photons to escape, or an escape f...

  6. The time evolution of HH~2 from four epochs of HST images

    CERN Document Server

    Raga, A C; Velázquez, P F; Esquivel, A; Bally, J

    2016-01-01

    We have analyzed four epochs of H$\\alpha$ and [S~II] HST images of the HH~1/2 outflow (covering a time interval from 1994 to 2014) to determine proper motions and emission line fluxes of the knots of HH~2. We find that our new proper motions agree surprisingly well with the motions measured by Herbig \\& Jones (1981), although there is partial evidence for a slight deceleration of the motion of the HH~2 knots from 1945 to 2014. We also measure the time-variability of the H$\\alpha$ intensities and the [S~II]/H$\\alpha$ line ratios, and find that knots H and A have the largest intensity variabilities (in $1994\\to 2014$). Knot H (which now dominates the HH~2 emission) has strengthened substantially, while keeping an approximately constant [S~II]/H$\\alpha$ ratio. Knot A has dramatically faded, and at the same time has had a substantial increase in its [S~II]/H$\\alpha$ ratio. Possible interpretations of these results are discussed.

  7. Statistical inversion of the LOFAR Epoch of Reionization experiment data model

    CERN Document Server

    Labropoulos, Panagiotis

    2010-01-01

    LOFAR is a new and innovative effort to build a radio-telescope operating at the multi-meter wavelength spectral window. One of the most exciting applications of LOFAR will be the search for redshifted 21-cm line emission from the Epoch of Reionization (EoR). It is currently believed that the Dark Ages, the period after recombination when the Universe turned neutral, lasted until around the Universe was 400,000 years old. During the EoR, objects started to form in the early universe and they were energetic enough to ionize neutral hydrogen. The precision and accuracy required to achieve this scientific goal, can be essentially translated into accumulating large amounts of data. The data model describing the response of the LOFAR telescope to the intensity distribution of the sky is characterized by the non-linearity of the parameters and the large level of noise compared to the desired cosmological signal. In this poster, we present the implementation of a statistically optimal map-making process and its prop...

  8. Coarse Initial Orbit Determination for a Geostationary Satellite Using Single-Epoch GPS Measurements

    Directory of Open Access Journals (Sweden)

    Ghangho Kim

    2015-04-01

    Full Text Available A practical algorithm is proposed for determining the orbit of a geostationary orbit (GEO satellite using single-epoch measurements from a Global Positioning System (GPS receiver under the sparse visibility of the GPS satellites. The algorithm uses three components of a state vector to determine the satellite’s state, even when it is impossible to apply the classical single-point solutions (SPS. Through consideration of the characteristics of the GEO orbital elements and GPS measurements, the components of the state vector are reduced to three. However, the algorithm remains sufficiently accurate for a GEO satellite. The developed algorithm was tested on simulated measurements from two or three GPS satellites, and the calculated maximum position error was found to be less than approximately 40 km or even several kilometers within the geometric range, even when the classical SPS solution was unattainable. In addition, extended Kalman filter (EKF tests of a GEO satellite with the estimated initial state were performed to validate the algorithm. In the EKF, a reliable dynamic model was adapted to reduce the probability of divergence that can be caused by large errors in the initial state.

  9. Power spectrum extraction for redshifted 21-cm epoch of reionization experiments: the LOFAR case

    CERN Document Server

    Harker, Geraint; Bernardi, Gianni; Brentjens, Michiel A; de Bruyn, A G; Ciardi, Benedetta; Jelic, Vibor; Koopmans, Leon V E; Labropoulos, Panagiotis; Mellema, Garrelt; Offringa, Andre; Pandey, V N; Pawlik, Andreas H; Schaye, Joop; Thomas, Rajat M; Yatawatta, Sarod

    2010-01-01

    One of the aims of the Low Frequency Array (LOFAR) Epoch of Reionization (EoR) project is to measure the power spectrum of variations in the intensity of redshifted 21-cm radiation from the EoR. The sensitivity with which this power spectrum can be estimated depends on the level of thermal noise and sample variance, and also on the systematic errors arising from the extraction process, in particular from the subtraction of foreground contamination. We model the extraction process using realistic simulations of the cosmological signal, the foregrounds and noise, and so estimate the sensitivity of the LOFAR EoR experiment to the redshifted 21-cm power spectrum. Detection of emission from the EoR should be possible within 360 hours of observation with a single station beam. Integrating for longer, and synthesizing multiple station beams within the primary (tile) beam, then enables us to extract progressively more accurate estimates of the power at a greater range of scales and redshifts. We discuss different obs...

  10. Discoveries from a Near-infrared Proper Motion Survey using Multi-epoch 2MASS Data

    CERN Document Server

    Kirkpatrick, J Davy; Burgasser, Adam J; Schurr, Steven D; Cutri, Roc M; Cushing, Michael C; Cruz, Kelle L; Sweet, Anne C; Knapp, Gillian R; Barman, Travis S; Bochanski, John J; Roellig, Thomas L; McLean, Ian S; McGovern, Mark R; Rice, Emily L

    2010-01-01

    We have conducted a 4030-square-deg near-infrared proper motion survey using multi-epoch data from the Two Micron All-Sky Survey (2MASS). We find 2778 proper motion candidates, 647 of which are not listed in SIMBAD. After comparison to DSS images, we find that 107 of our proper motion candidates lack counterparts at B-, R-, and I-bands and are thus 2MASS-only detections. We present results of spectroscopic follow-up of 188 targets that include the infrared-only sources along with selected optical-counterpart sources with faint reduced proper motions or interesting colors. We also establish a set of near-infrared spectroscopic standards with which to anchor near-infrared classifications for our objects. Among the discoveries are six young field brown dwarfs, five "red L" dwarfs, three L-type subdwarfs, twelve M-type subdwarfs, eight "blue L" dwarfs, and several T dwarfs. We further refine the definitions of these exotic classes to aid future identification of similar objects. We examine their kinematics and fi...

  11. Eliminating Polarized Leakage as a Systematic for 21 cm Epoch of Reionization Experiments

    Science.gov (United States)

    Aguirre, James E.; HERA Collaboration, PAPER Collaboration

    2016-01-01

    Because of the extreme brightness of foreground emission relative to the desired signal, experiments seeking the 21 cm HI signal from the epoch of reionization must employ foreground removal or avoidance strategies with high dynamic range. Almost all of these techniques rely on the spectral smoothness of the foreground emission, which is dominated by synchrotron emission. The polarized component of such emission can suffer Faraday rotation through the interstellar medium of the Milky Way, thereby inducing frequency structure which can be mistaken for real reionization signal. Therefore, it is of great importance for such experiments to eliminate leakage of Faraday-rotated, polarized emission into the unpolarized (Stokes I) component where the reionization signal lives. We discuss a number of approaches under investigation for mitigating this leakage in the PAPER and HERA experiments, including calibration and careful instrument design. Importantly, however, we show that the ionosphere may provide a very strong suppression of the polarized signal, when averaged over the integration times required for EoR experiments, by scrambling the phase of polarized sources. Moreover, this attenuation comes with very little suppression of the desired unpolarized signal. We consider the implications of this strategy for PAPER and HERA.

  12. Voracious vortexes in cataclysmic variables. Multi-epoch tomographic study of HT Cassiopeia

    CERN Document Server

    Neustroev, V V; Borisov, N V

    2016-01-01

    We present multi-epoch, time-resolved optical spectroscopic observations of the dwarf nova HT Cas, obtained during 1986, 1992, 1995 and 2005 with the aim to study the properties of emission structures in the system. We determined that the accretion disc radius, measured from the double-peaked emission line profiles, is persistently large and lies within the range of 0.45-0.52a, where a is the binary separation. This is close to the tidal truncation radius r_max=0.52a. This result contradicts with previous radius measurements. An extensive set of Doppler maps has revealed a very complex emission structure of the accretion disc. Apart from a ring of disc emission, the tomograms display at least three areas of enhanced emission: the hot spot from the area of interaction between the gas stream and the disc, which is superposed on the elongated spiral structure, and the extended bright region on the leading side of the disc, opposite to the location of the hot spot. The position of the hot spot in all the emission...

  13. Initial deep LOFAR observations of Epoch of Reionization windows: I. The North Celestial Pole

    CERN Document Server

    Yatawatta, S; Brentjens, M A; Labropoulos, P; Pandey, V N; Kazemi, S; Zaroubi, S; Koopmans, L V E; Offringa, A R; Jelic, V; Rubi, O Martinez; Veligatla, V; Wijnholds, S J; Brouw, W N; Bernardi, G; Ciardi, B; Daiboo, S; Harker, G; Mellema, G; Schaye, J; Thomas, R; Vedantham, H; Chapman, E; Abdalla, F B; Alexov, A; Anderson, J; Avruch, I M; Batejat, F; Bell, M E; Bell, M R; Bentum, M; Best, P; Bonafede, A; Bregman, J; Breitling, F; van de Brink, R H; Broderick, J W; Bruggen, M; Conway, J; de Gasperin, F; de Geus, E; Duscha, S; Falcke, H; Fallows, R A; Ferrari, C; Frieswijk, W; Garrett, M A; Griessmeier, J M; Gunst, A W; Hassall, T E; Hessels, J W T; Hoeft, M; Iacobelli, M; Juette, E; Karastergiou, A; Kondratiev, V I; Kramer, M; Kuniyoshi, M; Kuper, G; van Leeuwen, J; Maat, P; Mann, G; McKean, J P; Mevius, M; Mol, J D; Munk, H; Nijboer, R; Noordam, J E; Norden, M J; Orru, E; Paas, H; Pandey-Pommier, M; Pizzo, R; Polatidis, A G; Reich, W; Rottgering, H J A; Sluman, J; Smirnov, O; Stappers, B; Tagger, M; Tang, Y; Tasse, C; ter Veen, S; Vermeulen, R; van Weeren, R J; Wise, M; Wucknitz, O; Zarka, P

    2013-01-01

    The aim of the LOFAR Epoch of Reionization (EoR) project is to detect the spectral fluctuations of the redshifted HI 21cm signal. This signal is weaker by several orders of magnitude than the astrophysical foreground signals and hence, in order to achieve this, very long integrations, accurate calibration for stations and ionosphere and reliable foreground removal are essential. One of the prospective observing windows for the LOFAR EoR project will be centered at the North Celestial Pole (NCP). We present results from observations of the NCP window using the LOFAR highband antenna (HBA) array in the frequency range 115 MHz to 163 MHz. The data were obtained in April 2011 during the commissioning phase of LOFAR. We used baselines up to about 30 km. With about 3 nights, of 6 hours each, effective integration we have achieved a noise level of about 100 microJy/PSF in the NCP window. Close to the NCP, the noise level increases to about 180 microJy/PSF, mainly due to additional contamination from unsubtracted nea...

  14. Deformation Parameters Determination From The GPS Permanent and Epoch Observations In Poland.

    Science.gov (United States)

    Pfeil, M.; Jarosinski, M.

    The paper presents preliminary results of deformation parameters calculation from GPS observations for Poland. From geological point of view, the study area covers complex structural junction comprises of the Precambrian East European craton, heav- ily tectonised Teisseyre-Tornquist zone, the Palaeozoic platform, and also of young thrust and fold belt of the Carpathians. Complicated tectonic evolution, together with thermal field differentiation cause rheological contrasts and mechanical heterogene- ity in the earth crust that are expected to affect recent geokinematics of this area. Locations of the GPS stations have been chosen in order to sample major tectonic units of Poland representatively. For several stations coordinates changes had been computed and on that base, deformation parameters have been determined. Quality of these parameters depends on a distance between sites, utilised for their evaluation. This paper presents examples of deformation parameters, computed for GPS perma- nent and epoch observations, chosen from CERGOP, EXTENDED SAGET and EPN campaigns and supplemented by data from the EUREF network. Obtained deforma- tion have been compared with recent stress directions for the uppermost crust, as de- termined by mean of borehole breakout analysis.

  15. Panning for RRL Nuggets in the SDSS-DR9, Single Epoch Spectra

    CERN Document Server

    Wilhelm, Ronald; De Lee, Nathan

    2013-01-01

    The SDSS has been a gold mine for understanding properties of the Milky Way. Below, in the watershed, there remain small nuggets to be found flowing from the deepest recesses of the mine. The SDSS-DR9 included the release of the flux- and wavelength-calibrated, individual spectra which were subsequently combined to form the composite spectra found in previous SDSS data releases. These single-epoch spectra (SES) can be analyzed to find flux and spectral line variability, and to probe aspects of phase variations for objects such as RRL stars. For $\\sim 45%$ of the spectra in the RRL color range, SES were taken on separate nights, sometimes weeks apart. The remaining dataset have a time baseline of 0.75 to 1.5 hours and consist of 4-7 separate exposures. In my talk I will present details of our project to detect variability and to constrain the pulsation phase at the time of observation. I will discuss our auto-detection technique that uses division of all SES for a given star to search for variations in the flu...

  16. Multi-Epoch Observations of HD69830: High Resolution Spectroscopy and Limits to Variability

    CERN Document Server

    Beichman, C A; Tanner, A M; Bryden, G; Akeson, R L; Ciardi, D R; Boden, A F; Dodson-Robinson, S E; Salyk, C; Wyatt, M C

    2011-01-01

    The main-sequence solar-type star HD69830 has an unusually large amount of dusty debris orbiting close to three planets found via the radial velocity technique. In order to explore the dynamical interaction between the dust and planets, we have performed multi-epoch photometry and spectroscopy of the system over several orbits of the outer dust. We find no evidence for changes in either the dust amount or its composition, with upper limits of 5-7% (1 $\\sigma$ per spectral element) on the variability of the {\\it dust spectrum} over 1 year, 3.3% (1 $\\sigma$) on the broad-band disk emission over 4 years, and 33% (1 $\\sigma$) on the broad-band disk emission over 24 years. Detailed modeling of the spectrum of the emitting dust indicates that the dust is located outside of the orbits of the three planets and has a composition similar to main-belt, C-type asteroids asteroids in our solar system. Additionally, we find no evidence for a wide variety of gas species associated with the dust. Our new higher SNR spectra d...

  17. NEW EUROPEAN RECORDS AND FIRST EVIDENCE OF EPIDERMAL STRUCTURES OF SLOANEA L. FROM THE ITALIAN OLIGOCENE – REVISED TYPE AND ORIGINAL MATERIAL OF PRINCIPI 1916

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    LILLA HABLY

    2007-11-01

    Full Text Available Leaves of Sloanea elliptica (Andreánszky Z. Kvaèek & Hably and S. peolai (Principi Hably, Tamás & Cioppi  with preserved organic structures were found during the study of Principi’s collection from the Oligocene flora of Santa Giustina. Fossil leaves of Sloanea elliptica have so far been recorded exclusively from the Palaeogene Basin of the Inner Carpathian Region, i.e. from the Lower Oligocene strata of Hungary and Slovenia, whereas S. peolai has been described from a single locality, Chiavon in Italy. Organic structure of S. peolai hitherto has not been recorded. The mass occurrence of Sloanea elliptica in the fossil assemblage of Santa Giustina indicates that its area was much more extensive than it was presumed. It was a characteristic element mainly of Oligocene floras, and even predominated them. This is the first record of the co-occurrence of two Sloanea species described on the basis of leaf remains. During the study 6 types and more than 30 illustrated specimens published in Principi's monograph were revised and identified as S. elliptica.    

  18. First fossil record of Alphonsea Hk. f. & T. (Annonaceae) from the Late Oligocene sediments of Assam, India and comments on its phytogeography.

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    Srivastava, Gaurav; Mehrotra, Rakesh C

    2013-01-01

    A new fossil leaf impression of Alphonsea Hk. f. & T. of the family Annonaceae is described from the Late Oligocene sediments of Makum Coalfield, Assam, India. This is the first authentic record of the fossil of Alphonsea from the Tertiary rocks of South Asia. The Late Oligocene was the time of the last significant globally warm climate and the fossil locality was at 10°-15°N palaeolatitude. The known palaeoflora and sedimentological studies indicate a fluvio-marine deltaic environment with a mosaic of mangrove, fluvial, mire and lacustrine depositional environments. During the depositional period the suturing between the Indian and Eurasian plates was not complete to facilitate the plant migration. The suturing was over by the end of the Late Oligocene/beginning of Early Miocene resulting in the migration of the genus to Southeast Asia where it is growing profusely at present. The present study is in congruence with the earlier published palaeofloral and molecular phylogenetic data. The study also suggests that the Indian plate was not only a biotic ferry during its northward voyage from Gondwana to Asia but also a place for the origin of several plant taxa.

  19. First fossil record of Alphonsea Hk. f. & T. (Annonaceae from the Late Oligocene sediments of Assam, India and comments on its phytogeography.

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    Gaurav Srivastava

    Full Text Available A new fossil leaf impression of Alphonsea Hk. f. & T. of the family Annonaceae is described from the Late Oligocene sediments of Makum Coalfield, Assam, India. This is the first authentic record of the fossil of Alphonsea from the Tertiary rocks of South Asia. The Late Oligocene was the time of the last significant globally warm climate and the fossil locality was at 10°-15°N palaeolatitude. The known palaeoflora and sedimentological studies indicate a fluvio-marine deltaic environment with a mosaic of mangrove, fluvial, mire and lacustrine depositional environments. During the depositional period the suturing between the Indian and Eurasian plates was not complete to facilitate the plant migration. The suturing was over by the end of the Late Oligocene/beginning of Early Miocene resulting in the migration of the genus to Southeast Asia where it is growing profusely at present. The present study is in congruence with the earlier published palaeofloral and molecular phylogenetic data. The study also suggests that the Indian plate was not only a biotic ferry during its northward voyage from Gondwana to Asia but also a place for the origin of several plant taxa.

  20. Late Oligocene-Early Miocene magnetochronology of the mammalian faunas in the Lanzhou Basin-environmental changes in the NE margin of the Tibetan Plateau

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    Zhang, Peng; Ao, Hong; Dekkers, Mark J.; Li, Yongxiang; An, Zhisheng

    2016-11-01

    A large number of terrestrial mammalian fossils were reported in the well-exposed Paleogene and Neogene fluvio-lacustrine strata in Western China. Their accurate ages are crucial to understand the mammalian and environmental evolution associated with the step-wise uplift of the Tibetan Plateau. At present their ages are surprisingly poorly constrained. Here, we present a high-resolution magnetostratigraphic dating of the Late Oligocene-Early Miocene mammal assemblages from a 233-m thick fluvio-lacustrine section in the Lanzhou Basin located at the northeastern margin of the Tibetan Plateau, China. The results suggest that the section spans from the polarity subchron C6Cn.2r to C5En, i.e. ranging from ca 23 to 18 Ma. This magnetochronology provides considerably more robust ages for three associated land mammalian faunal assemblages. Updated ages end the debate on existing ambiguous and distinctly different magnetostratigraphic correlations for those Late Oligocene-Early Miocene assemblages. The new ages now enable precise correlation of these faunas to the European Land Mammal and North American Land Mammal Ages. The faunal assemblages further suggest a mixed setting of woodlands and grasslands associated with a humid environment in the Lanzhou Basin during the Late Oligocene-Early Miocene, in contrast to its modern poor vegetation cover and arid environment.

  1. Oligocene-Early Miocene Magnetochronology of the Mammalian Faunas in the Lanzhou Basin—Environmental Changes in the NE Margin of the Tibetan Plateau

    Science.gov (United States)

    Zhang, P.; Ao, H.; Dekkers, M. J.; Li, Y.; An, Z.

    2016-12-01

    A large number of terrestrial mammalian fossils were reported in the well-exposed Paleogene and Neogene fluvio-lacustrine strata in Western China. Their accurate ages are crucial to understand the mammal and environmental evolution associated with the step-wise uplift of the Tibetan Plateau. To date their ages are surprisingly poorly constrained. Here, we present a high-resolution magnetostratigraphic dating of the Oligocene-Early Miocene mammal assemblages from a 383-m thick fluvio-lacustrine section in the Lanzhou Basin located at the northeastern margin of the Tibetan Plateau (China). The section is suggested to span from the uppermost part of polarity chron C12r to chron C5En, i.e. ranging from ca 31.5 to 18 Ma. This magnetochronology provides new numerical ages for five Oligocene-Early Miocene land mammalian faunal assemblages within the biostratigraphy and enables precise correlation of these faunas to the European Land Mammal Age and North American Land Mammal Ages. The faunal assemblages further suggest a mixed setting of woodlands and grasslands associated with humid environment in the Lanzhou Basin during the Oligocene-Early Miocene, in contrast to its modern poor vegetation cover and arid environment.

  2. Oligocene-Early Miocene river incision near the first bend of the Yangze River: Insights from apatite (U-Th-Sm)/He thermochronology

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    Shen, Xiaoming; Tian, Yuntao; Li, Dewen; Qin, Siwei; Vermeesch, Pieter; Schwanethal, James

    2016-09-01

    The southeastern Tibetan Plateau is deeply incised by three parallel rivers, the Salween, the Mekong and the Yangtze. The river incision and surface uplift histories of this landscape are hotly debated. This study presents bedrock apatite (U-Th-Sm)/He data from a 1800 m vertical profile, located near the first bend of the Yangtze River. Ages range from 20 to 30 Ma, indicating an Oligocene-Early Miocene phase of moderate river incision at a rate of 0.10-0.18 mm/yr. This is considerably older than elsewhere in the region, but consistent with a previously proposed phase of Eocene surface uplift inferred from stable isotope geochemistry. We consider the implications of the new data under two different tectonic models. If the surface uplift and river incision resulted from lower crustal flow, the new results require such flow to have commenced at Oligocene-Early Miocene time rather than during the previously proposed Late Miocene. Alternatively, Oligocene to Early Miocene plateau growth might have resulted from transpressional deformation in the southeastern Tibetan Plateau.

  3. Terrestrial responses of low-latitude Asia to the Eocene–Oligocene climate transition revealed by integrated chronostratigraphy

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    Y.-X. Li

    2015-07-01

    Full Text Available The Paleogene sedimentary records from southern China hold important clues to the impacts of the Cenozoic climate changes on low-latitudes. However, although there are extensive Paleogene terrestrial archives and some contain abundant fossils in this region, few are accurately dated and have a temporal resolution adequate to decipher climate changes. Here we present a detailed stratigraphic and paleomagnetic study of a fossiliferous late Paleogene succession in the Maoming Basin, Guangdong Province. The succession consists of oil shale of the Youganwo Formation (Fm in the lower part and massive pebbly coarse sandstones of the overlying Huangniuling Fm in the upper part. The conformable transition from oil shale to sandstones represents a major depositional environmental change from a lacustrine to a deltaic environment. The substantially refined chronostratigraphic framework is established based on the litho-, bio-, cyclo-, and magnetostratiphic data that place the environmental transition at 33.88 Ma, coinciding with the Eocene–Oligocene climate transition (EOT at ~ 33.7 to ~ 33.9 Ma. We suggest that the transition from a lacustrine to deltaic environment in Maoming Basin represents terrestrial responses to the EOT and indicates a significant reduction in hydrodynamics in low-latitude regions during the global cooling at EOT.

  4. Self-sedimented diatom mats as agents of exceptional fossil preservation in the Oligocene Florissant lake beds, Colorado, United States

    Science.gov (United States)

    Harding, Ian C.; Chant, Loraine S.

    2000-03-01

    Microbial mats play a major role in the formation of exceptionally preserved fossil deposits by overgrowing and binding organic remains and sedimentary particles. This minimizes hydrodynamic and biological disruption of dead organisms and sedimentary laminae, but published works all implicate prokaryotic cyanobacteria as the microbial agent. However, exceptionally well preserved macrofossils of the Oligocene Florissant lake beds (Colorado, United States) are enveloped in matted aggregations of mucous-secreting, pennate diatom frustules. It is suggested that the macrobiota became entrapped in mucous-secreting mats of surface water blooms of planktonic diatoms in lake Florissant. As the mats and the incorporated macrobiota were sedimented out of the water column, the mucosic mats and their associated bacterial communities arrested decay and promoted preservation of refractory tissues. Thus, by a completely different mechanism, the diatom mats fulfilled the same preservational role previously suggested for cyanobacterial mats. This hitherto unrecognized mode of preservation may be an important causative factor in the formation of exceptionally preserved lacustrine fossil biotas.

  5. Systematic and taphonomic insights of fossilized feathers: A new occurrence from the Oligocene of Taubaté Basin (SE, Brazil)

    Science.gov (United States)

    Prado, Gustavo M. E. M.; Anelli, Luiz E.; Pacheco, Mírian L. A. F.; Petri, Setembrino; Romero, Guilherme R.

    2016-12-01

    Feathers are rare in the fossil record because they have a low fossilization potential. Despite their palaeobiological significance, they also provide important palaeoecological and taphonomic information. Here, we report a new occurrence of three isolated feathers from the shales of the Oligocene Tremembé Formation (Taubaté Basin, SE Brazil). Their possible taxonomic affinities and taphonomic features are also discussed. Analyses identified the specimens as representatives of two pennaceous morphotypes (i.e., a contour and a rectrice feather). Both are preserved as carbonized traces, although, due taphonomic processes, they show different degrees of preservation. Since the Tremembé Formation is responsible for the most diverse record of Cenozoic birds, and because water-adapted birds (e.g., anseriformes and phoenicopteriformes) occur in this unit, it is highly possible that these feathers belonged to these aquatic taxa. Further investigations should concentrate on geochemical and microscopic techniques in order to reveal additional taxonomic and paleoecological features currently unknown in Paleogene birds of Brazil.

  6. THE EARLY OLIGOCENE FLORA OF SANTA GIUSTINA (LIGURIA, ITALY - REVISION AND COMPARISON WITH THE FLORA OF THE TARD CLAY FORMATION

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    LILLA HABLY

    2010-11-01

    Full Text Available Based on palaeobotanical material preserved at the University of Genoa, Italy (DIP.TE.RIS., a revision of the Early Oligocene flora of Santa Giustina, as well as the 1916 monograph of Principi, was undertaken. It is shown that apart from members of the Lauraceae family, Eotrigonobalanus furcinervis and Sloanea olmediaefolia were dominant in the flora, which was mainly composed of warmth-demanding species. The site is primarily characterized by remnants of the vegetation developed under warm and moist climate and abundant water supply. A few additional plants from the neighboring zonal vegetation are also present. The flora is quite reminiscent of that of the Tard Clay Formation, part of the Inner Carpathian Region, providing a proven link to the floristic relationships of these areas. Up to the Pre-Neogene, the Inner Carpathian Region and the surrounding Alpine-Carpathian-Dinaric Region was composed of a composite terrane that 1 existed independently from Stable Europe, and, 2 had a much more southerly position than today. This terrane collage was sharply bordered from all directions except west, as is supported by new evidences of the floristic affinities with the Santa Giustina flora. 

  7. New postcranial remains of large toxodontian notoungulates from the late Oligocene of Mendoza, Argentina and their systematic implications

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    Santiago Hernández Del Pino

    2017-03-01

    Full Text Available During the last decade, the Deseadan (late Oligocene Quebrada Fiera locality, Mendoza Province, Argentina, has provided a large amount of mammal remains. Taxonomic studies have shown the presence of faunal elements common with other Deseadan associations from Patagonia and lower latitudes (Salla, Bolivia, as well as endemic taxa of different groups of mammals (Notohippidae, Leontiniidae, Homalodotheriidae, Hegetotheriidae, and Metatheria and even a gastropod. In this work, we present a taxonomic and phylogenetic analysis of a set of postcranial fossils of three families of the suborder Toxodontia (Notoungulata. The postcranial elements are assigned to taxa previously recognized at Quebrada Fiera, such as the leontiniid Gualta cuyana and the homalodotheriid Asmodeus petrasnerus, but also to the family Toxodontidae that is represented by Proadinotherium sp. and another larger toxodontid; a few dental remains of Proadinotherium are also included as this is the first time that toxodontids from Quebrada Fiera are described. In the case of A. petrasnerus, an almost complete calcaneum allows us to expand the diagnosis of this taxon. The bones assigned to G. cuyana enlarge the anatomical knowledge of this species. In turn, the presence of the genus Proadinotherium extends its geographic distribution in Argentina and adds to the extra-Patagonian record of P. saltoni from Salla, Bolivia. Phylogenetic results do not differ much from previous analyses using postcranial characters, and the obtained consensus trees show low node supports. The various phylogenetic analyses performed here provide a more robust framework to interpret the relationships of the studied taxa.

  8. Leaves of Berberidaceae (Berberis and Mahonia) from Oligocene sediments, near Tepexi de Rodríguez, Puebla.

    Science.gov (United States)

    Ramírez; Cevallos-Ferriz

    2000-07-01

    From the Oligocene Los Ahuehuetes locality, near Tepexi de Rodríguez, Puebla, Mexico, five new plant species are described based on their leaf architecture. The presence of brochidodromous or acrodromous venation, and secondary veins forming angular (versus rounded) arcs, are well defined characters in the fossil material that relate it to Berberidaceae. Comparison with the leaves and leaflets of extant and fossil plants allow the recognition of one Mahonia and four Berberis new species. The lack of detailed information on leaf architecture in Berberidaceae limits the evaluation of the taxonomic relationships that can be suggested between fossil and extant plants. However, from a biogeographic point of view the presence of these new fossil plants supports the hypothesis of a North American origin of the Orientalis Groups of Mahonia, to which a lineage of Berberis may be added. Furthermore, two of the new species suggest the dispersal, some time during the Tertiary, of a lineage that today forms the Australis Group of Berberis from low latitude North America to South America. The movement of the Chortis Block is proposed as an alternative to explain the dispersal of a growing list of plants from north to south in the Americas. Only through future geological and palaeobotanical work can this hypothesis be corroborated.

  9. Analysis of short single rest/activation epoch fMRI by self-organizing map neural network

    Science.gov (United States)

    Erberich, Stephan G.; Dietrich, Thomas; Kemeny, Stefan; Krings, Timo; Willmes, Klaus; Thron, Armin; Oberschelp, Walter

    2000-04-01

    Functional magnet resonance imaging (fMRI) has become a standard non invasive brain imaging technique delivering high spatial resolution. Brain activation is determined by magnetic susceptibility of the blood oxygen level (BOLD effect) during an activation task, e.g. motor, auditory and visual tasks. Usually box-car paradigms have 2 - 4 rest/activation epochs with at least an overall of 50 volumes per scan in the time domain. Statistical test based analysis methods need a large amount of repetitively acquired brain volumes to gain statistical power, like Student's t-test. The introduced technique based on a self-organizing neural network (SOM) makes use of the intrinsic features of the condition change between rest and activation epoch and demonstrated to differentiate between the conditions with less time points having only one rest and one activation epoch. The method reduces scan and analysis time and the probability of possible motion artifacts from the relaxation of the patients head. Functional magnet resonance imaging (fMRI) of patients for pre-surgical evaluation and volunteers were acquired with motor (hand clenching and finger tapping), sensory (ice application), auditory (phonological and semantic word recognition task) and visual paradigms (mental rotation). For imaging we used different BOLD contrast sensitive Gradient Echo Planar Imaging (GE-EPI) single-shot pulse sequences (TR 2000 and 4000, 64 X 64 and 128 X 128, 15 - 40 slices) on a Philips Gyroscan NT 1.5 Tesla MR imager. All paradigms were RARARA (R equals rest, A equals activation) with an epoch width of 11 time points each. We used the self-organizing neural network implementation described by T. Kohonen with a 4 X 2 2D neuron map. The presented time course vectors were clustered by similar features in the 2D neuron map. Three neural networks were trained and used for labeling with the time course vectors of one, two and all three on/off epochs. The results were also compared by using a

  10. Effects of Varying Epoch Lengths, Wear Time Algorithms, and Activity Cut-Points on Estimates of Child Sedentary Behavior and Physical Activity from Accelerometer Data.

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    Jorge A Banda

    Full Text Available To examine the effects of accelerometer epoch lengths, wear time (WT algorithms, and activity cut-points on estimates of WT, sedentary behavior (SB, and physical activity (PA.268 7-11 year-olds with BMI ≥ 85th percentile for age and sex wore accelerometers on their right hips for 4-7 days. Data were processed and analyzed at epoch lengths of 1-, 5-, 10-, 15-, 30-, and 60-seconds. For each epoch length, WT minutes/day was determined using three common WT algorithms, and minutes/day and percent time spent in SB, light (LPA, moderate (MPA, and vigorous (VPA PA were determined using five common activity cut-points. ANOVA tested differences in WT, SB, LPA, MPA, VPA, and MVPA when using the different epoch lengths, WT algorithms, and activity cut-points.WT minutes/day varied significantly by epoch length when using the NHANES WT algorithm (p < .0001, but did not vary significantly by epoch length when using the ≥ 20 minute consecutive zero or Choi WT algorithms. Minutes/day and percent time spent in SB, LPA, MPA, VPA, and MVPA varied significantly by epoch length for all sets of activity cut-points tested with all three WT algorithms (all p < .0001. Across all epoch lengths, minutes/day and percent time spent in SB, LPA, MPA, VPA, and MVPA also varied significantly across all sets of activity cut-points with all three WT algorithms (all p < .0001.The common practice of converting WT algorithms and activity cut-point definitions to match different epoch lengths may introduce significant errors. Estimates of SB and PA from studies that process and analyze data using different epoch lengths, WT algorithms, and/or activity cut-points are not comparable, potentially leading to very different results, interpretations, and conclusions, misleading research and public policy.

  11. The Karangatian epoch in the Neopleistocene history of the Black Sea

    Science.gov (United States)

    Yanko-Hombach, Valentina; Motnenko, Irena

    2016-04-01

    Black Sea Quaternary history shows an alternation of transgressive and regressive stages that are related to global climate change and pronounced due to semi-isolation from the World Ocean. In warm epochs, the Black Sea is connected to the Mediterranean Sea (i.e., World Ocean) via connecting seas and straits. In cold epochs, it becomes isolated or connects to the Caspian Sea via the Manych outlet. During transgressions, sea level rises as does salinity. During regressions, when it drops below the Bosphorus sill, the basin transforms into an isolated lake. During transgressions, organisms migrate into the Black Sea from either the Mediterranean or Caspian. Such migrations affect assemblage structure and increase the number of species, especially in case of Mediterranean transgressions. During regressive stages, the number of species drops, and only holeuryhaline Mediterranean species can survive the lowering of salinity (Yanko-Hombach, 2007). The most powerful Mediterranean transgression in the Black Sea occurred during the Mikulino (MIS 5e) interglacial, corresponding to the central European Eemian interglacial; it is usually compared with the Alpine Riss-Würm interglacial. Clear traces of this transgression are preserved in coastal outcrops exposed in tectonically elevated terraces of the Kerch and Taman peninsulas, and Caucasus. They are also found in numerous cores and drill holes recovered from the Black Sea bottom. These traces contain numerous Mediterranean organisms (molluscs, foraminifera, ostracoda, etc.), many of which do not live in the Black Sea today. These sediments were first described by N.I. Andrusov (1925) on Cape Karangat, Kerch peninsula, in the early XX century. He called them "Tyrrenean" as they were similar to those in the "Tyrrenean" beds that form a coastal terrace in the Mediterranean. This similarity enabled him to conclude that the Mediterranean and Black Sea basins were connected to each other. Later, the "Tyrrenian" beds were renamed

  12. Multi-band, Multi-epoch Observations of the Transiting Warm Jupiter WASP-80b

    Science.gov (United States)

    Fukui, Akihiko; Kawashima, Yui; Ikoma, Masahiro; Narita, Norio; Onitsuka, Masahiro; Ita, Yoshifusa; Onozato, Hiroki; Nishiyama, Shogo; Baba, Haruka; Ryu, Tsuguru; Hirano, Teruyuki; Hori, Yasunori; Kurosaki, Kenji; Kawauchi, Kiyoe; Takahashi, Yasuhiro H.; Nagayama, Takahiro; Tamura, Motohide; Kawai, Nobuyuki; Kuroda, Daisuke; Nagayama, Shogo; Ohta, Kouji; Shimizu, Yasuhiro; Yanagisawa, Kenshi; Yoshida, Michitoshi; Izumiura, Hideyuki

    2014-08-01

    WASP-80b is a warm Jupiter transiting a bright late-K/early-M dwarf, providing a good opportunity to extend the atmospheric study of hot Jupiters toward the lower temperature regime. We report multi-band, multi-epoch transit observations of WASP-80b by using three ground-based telescopes covering from optical (g', R c, and I c bands) to near-infrared (NIR; J, H, and K s bands) wavelengths. We observe 5 primary transits, each in 3 or 4 different bands simultaneously, obtaining 17 independent transit light curves. Combining them with results from previous works, we find that the observed transmission spectrum is largely consistent with both a solar abundance and thick cloud atmospheric models at a 1.7σ discrepancy level. On the other hand, we find a marginal spectral rise in the optical region compared to the NIR region at the 2.9σ level, which possibly indicates the existence of haze in the atmosphere. We simulate theoretical transmission spectra for a solar abundance but hazy atmosphere, finding that a model with equilibrium temperature of 600 K can explain the observed data well, having a discrepancy level of 1.0σ. We also search for transit timing variations, but find no timing excess larger than 50 s from a linear ephemeris. In addition, we conduct 43 day long photometric monitoring of the host star in the optical bands, finding no significant variation in the stellar brightness. Combined with the fact that no spot-crossing event is observed in the five transits, our results confirm previous findings that the host star appears quiet for spot activities, despite the indications of strong chromospheric activities.

  13. A shift of thermokarst lakes from carbon sources to sinks during the Holocene epoch

    Science.gov (United States)

    Walter Anthony, K. M.; Zimov, S. A.; Grosse, G.; Jones, Miriam C.; Anthony, P.; Chapin, F. S.; Finlay, J. C.; Mack, M. C.; Davydov, S.; Frenzel, P.F.; Frolking, S.

    2014-01-01

    Thermokarst lakes formed across vast regions of Siberia and Alaska during the last deglaciation and are thought to be a net source of atmospheric methane and carbon dioxide during the Holocene epoch1,2,3,4. However, the same thermokarst lakes can also sequester carbon5, and it remains uncertain whether carbon uptake by thermokarst lakes can offset their greenhouse gas emissions. Here we use field observations of Siberian permafrost exposures, radiocarbon dating and spatial analyses to quantify Holocene carbon stocks and fluxes in lake sediments overlying thawed Pleistocene-aged permafrost. We find that carbon accumulation in deep thermokarst-lake sediments since the last deglaciation is about 1.6 times larger than the mass of Pleistocene-aged permafrost carbon released as greenhouse gases when the lakes first formed. Although methane and carbon dioxide emissions following thaw lead to immediate radiative warming, carbon uptake in peat-rich sediments occurs over millennial timescales. We assess thermokarst-lake carbon feedbacks to climate with an atmospheric perturbation model and find that thermokarst basins switched from a net radiative warming to a net cooling climate effect about 5,000 years ago. High rates of Holocene carbon accumulation in 20 lake sediments (47±10 grams of carbon per square metre per year; mean±standard error) were driven by thermokarst erosion and deposition of terrestrial organic matter, by nutrient release from thawing permafrost that stimulated lake productivity and by slow decomposition in cold, anoxic lake bottoms. When lakes eventually drained, permafrost formation rapidly sequestered sediment carbon. Our estimate of about 160petagrams of Holocene organic carbon in deep lake basins of Siberia and Alaska increases the circumpolar peat carbon pool estimate for permafrost regions by over 50 per cent (ref. 6). The carbon in perennially frozen drained lake sediments may become vulnerable to mineralization as permafrost disappears7

  14. Tropical cyclones and permanent El Niño in the early Pliocene epoch.

    Science.gov (United States)

    Fedorov, Alexey V; Brierley, Christopher M; Emanuel, Kerry

    2010-02-25

    Tropical cyclones (also known as hurricanes and typhoons) are now believed to be an important component of the Earth's climate system. In particular, by vigorously mixing the upper ocean, they can affect the ocean's heat uptake, poleward heat transport, and hence global temperatures. Changes in the distribution and frequency of tropical cyclones could therefore become an important element of the climate response to global warming. A potential analogue to modern greenhouse conditions, the climate of the early Pliocene epoch (approximately 5 to 3 million years ago) can provide important clues to this response. Here we describe a positive feedback between hurricanes and the upper-ocean circulation in the tropical Pacific Ocean that may have been essential for maintaining warm, El Niño-like conditions during the early Pliocene. This feedback is based on the ability of hurricanes to warm water parcels that travel towards the Equator at shallow depths and then resurface in the eastern equatorial Pacific as part of the ocean's wind-driven circulation. In the present climate, very few hurricane tracks intersect the parcel trajectories; consequently, there is little heat exchange between waters at such depths and the surface. More frequent and/or stronger hurricanes in the central Pacific imply greater heating of the parcels, warmer temperatures in the eastern equatorial Pacific, warmer tropics and, in turn, even more hurricanes. Using a downscaling hurricane model, we show dramatic shifts in the tropical cyclone distribution for the early Pliocene that favour this feedback. Further calculations with a coupled climate model support our conclusions. The proposed feedback should be relevant to past equable climates and potentially to contemporary climate change.

  15. THE EFFECT OF INTERPLANETARY SCINTILLATION ON EPOCH OF REIONIZATION POWER SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Trott, Cathryn M.; Tingay, Steven J. [International Centre for Radio Astronomy Research, Curtin University, Bentley WA (Australia)

    2015-11-20

    Interplanetary Scintillation (IPS) induces intensity fluctuations in small angular size astronomical radio sources via the distortive effects of spatially and temporally varying electron density associated with outflows from the Sun. These radio sources are a potential foreground contaminant signal for redshifted HI emission from the Epoch of Reionization (EoR) because they yield time-dependent flux density variations in bright extragalactic point sources. Contamination from foreground continuum sources complicates efforts to discriminate the cosmological signal from other sources in the sky. In IPS, at large angles from the Sun applicable to EoR observations, weak scattering induces spatially and temporally correlated fluctuations in the measured flux density of sources in the field, potentially affecting the detectability of the EoR signal by inducing non-static variations in the signal strength. In this work, we explore the impact of interplanetary weak scintillation on EoR power spectrum measurements, accounting for the instrumental spatial and temporal sampling. We use published power spectra of electron density fluctuations and parameters of EoR experiments to derive the IPS power spectrum in the wavenumber phase space of EoR power spectrum measurements. The contrast of IPS power to expected cosmological power is used as a metric to assess the impact of IPS. We show that IPS has a spectral structure different from power from foregrounds alone, but the additional leakage into the EoR observation parameter space is negligible under typical IPS conditions, unless data are used from deep within the foreground contamination region.

  16. INFACE and EPOCH Database: A Benchmark for Face Recognition inUncontrolled Conditions

    Directory of Open Access Journals (Sweden)

    M. Parisa Beham

    2014-08-01

    Full Text Available The main focus of our study is to build a database of labeled face images display with wide variations in pose, lighting, appearance and age. Recognizing human faces amid natural setting is emerging as a critically important and technically challenging computer vision problem. Most of the previous cases of analysis to study the specific variations of the face recognition problem focused on recognition of faces captured under controlled environment in standard laboratory setting. These variations include position, pose, lighting, background, camera quality and gender. But in real environment, there are innumerable applications in which there is little or no control over such variations. In this study, we introduce two novel database viz. “INFACE” and “EPOCH”, which can effectively contribute to the face recognition research, in general and suited to the Indian setting (appearance, expressions, etc. in particular. The former data base (“INFACE”, includes around 7400 face images of 37 individuals collected from approximately 45 Indian movies. The images of later data base (“EPOCH” portray the variations with age. It contains 1000 images of 10 individuals spanning four age groups. The data base specimens of INFACE have high degree of variability (in scale, location, orientation, pose, expression, illumination, appearance and degree of occlusion which one could ever see in natural world. EPOCH database is providing a large set of unconstrained face images which includes age variance of an individual. In addition to the individuality of the face, these databases provide additional information on pose, gender, expression, location etc. Specific annotations for each image have been stored as XML for easy retrieval. These databases will be made public to catalyze research and development for accurate face recognition.

  17. Irregular tropical glacier retreat over the Holocene epoch driven by progressive warming.

    Science.gov (United States)

    Jomelli, Vincent; Khodri, Myriam; Favier, Vincent; Brunstein, Daniel; Ledru, Marie-Pierre; Wagnon, Patrick; Blard, Pierre-Henri; Sicart, Jean-Emmanuel; Braucher, Régis; Grancher, Delphine; Bourlès, Didier Louis; Braconnot, Pascale; Vuille, Mathias

    2011-06-08

    The causes and timing of tropical glacier fluctuations during the Holocene epoch (10,000 years ago to present) are poorly understood. Yet constraining their sensitivity to changes in climate is important, as these glaciers are both sensitive indicators of climate change and serve as water reservoirs for highland regions. Studies have so far documented extra-tropical glacier fluctuations, but in the tropics, glacier-climate relationships are insufficiently understood. Here we present a (10)Be chronology for the past 11,000 years (11 kyr), using 57 moraines from the Bolivian Telata glacier (in the Cordillera Real mountain range). This chronology indicates that Telata glacier retreated irregularly. A rapid and strong melting from the maximum extent occurred from 10.8 ± 0.9 to 8.5 ± 0.4 kyr ago, followed by a slower retreat until the Little Ice Age, about 200 years ago. A dramatic increase in the rate of retreat occurred over the twentieth century. A glacier-climate model indicates that, relative to modern climate, annual mean temperature for the Telata glacier region was -3.3 ± 0.8 °C cooler at 11 kyr ago and remained -2.1 ± 0.8 °C cooler until the end of the Little Ice Age. We suggest that long-term warming of the eastern tropical Pacific and increased atmospheric temperature in response to enhanced austral summer insolation were the main drivers for the long-term Holocene retreat of glaciers in the southern tropics.

  18. Analysing the 21 cm signal from the epoch of reionization with artificial neural networks

    Science.gov (United States)

    Shimabukuro, Hayato; Semelin, Benoit

    2017-07-01

    The 21 cm signal from the epoch of reionization should be observed within the next decade. While a simple statistical detection is expected with Square Kilometre Array (SKA) pathfinders, the SKA will hopefully produce a full 3D mapping of the signal. To extract from the observed data constraints on the parameters describing the underlying astrophysical processes, inversion methods must be developed. For example, the Markov Chain Monte Carlo method has been successfully applied. Here, we test another possible inversion method: artificial neural networks (ANNs). We produce a training set that consists of 70 individual samples. Each sample is made of the 21 cm power spectrum at different redshifts produced with the 21cmFast code plus the value of three parameters used in the seminumerical simulations that describe astrophysical processes. Using this set, we train the network to minimize the error between the parameter values it produces as an output and the true values. We explore the impact of the architecture of the network on the quality of the training. Then we test the trained network on the new set of 54 test samples with different values of the parameters. We find that the quality of the parameter reconstruction depends on the sensitivity of the power spectrum to the different parameters at a given redshift, that including thermal noise and sample variance decreases the quality of the reconstruction and that using the power spectrum at several redshifts as an input to the ANN improves the quality of the reconstruction. We conclude that ANNs are a viable inversion method whose main strength is that they require a sparse exploration of the parameter space and thus should be usable with full numerical simulations.

  19. Multi-band, multi-epoch observations of the transiting warm Jupiter WASP-80b

    Energy Technology Data Exchange (ETDEWEB)

    Fukui, Akihiko; Kuroda, Daisuke [Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Asakuchi, Okayama 719-0232 (Japan); Kawashima, Yui; Ikoma, Masahiro; Kurosaki, Kenji [Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-0033 (Japan); Narita, Norio; Nishiyama, Shogo; Takahashi, Yasuhiro H.; Nagayama, Shogo [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Onitsuka, Masahiro; Baba, Haruka; Ryu, Tsuguru [The Graduate University for Advanced Studies, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Ita, Yoshifusa; Onozato, Hiroki [Astronomical Institute, Graduate School of Science, Tohoku University, 6-3 Aramaki Aoba, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Hirano, Teruyuki; Kawauchi, Kiyoe [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Hori, Yasunori [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Nagayama, Takahiro [Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan); Tamura, Motohide [Department of Astronomy, Graduate School of Science, The University of Tokyo, and National Astronomical Observatory of Japan (Japan); Kawai, Nobuyuki, E-mail: afukui@oao.nao.ac.jp [Department of Physics, Tokyo Institute of Technology, 2-12-1, Oookayama, Meguro, Tokyo 152-8551 (Japan); and others

    2014-08-01

    WASP-80b is a warm Jupiter transiting a bright late-K/early-M dwarf, providing a good opportunity to extend the atmospheric study of hot Jupiters toward the lower temperature regime. We report multi-band, multi-epoch transit observations of WASP-80b by using three ground-based telescopes covering from optical (g', R{sub c}, and I{sub c} bands) to near-infrared (NIR; J, H, and K{sub s} bands) wavelengths. We observe 5 primary transits, each in 3 or 4 different bands simultaneously, obtaining 17 independent transit light curves. Combining them with results from previous works, we find that the observed transmission spectrum is largely consistent with both a solar abundance and thick cloud atmospheric models at a 1.7σ discrepancy level. On the other hand, we find a marginal spectral rise in the optical region compared to the NIR region at the 2.9σ level, which possibly indicates the existence of haze in the atmosphere. We simulate theoretical transmission spectra for a solar abundance but hazy atmosphere, finding that a model with equilibrium temperature of 600 K can explain the observed data well, having a discrepancy level of 1.0σ. We also search for transit timing variations, but find no timing excess larger than 50 s from a linear ephemeris. In addition, we conduct 43 day long photometric monitoring of the host star in the optical bands, finding no significant variation in the stellar brightness. Combined with the fact that no spot-crossing event is observed in the five transits, our results confirm previous findings that the host star appears quiet for spot activities, despite the indications of strong chromospheric activities.

  20. The Egyptian geomagnetic reference field to the Epoch, 2010.0

    Science.gov (United States)

    Deebes, H. A.; Abd Elaal, E. M.; Arafa, T.; Lethy, A.; El Emam, A.; Ghamry, E.; Odah, H.

    2017-06-01

    The present work is a compilation of two tasks within the frame of the project ;Geomagnetic Survey & Detailed Geomagnetic Measurements within the Egyptian Territory; funded by the ;Science and Technology Development Fund agency (STDF);. The National Research Institute of Astronomy and Geophysics (NRIAG), has conducted a new extensive land geomagnetic survey that covers the whole Egyptian territory. The field measurements have been done at 3212 points along all the asphalted roads, defined tracks, and ill-defined tracks in Egypt; with total length of 11,586 km. In the present work, the measurements cover for the first time new areas as: the southern eastern borders of Egypt including Halayeb and Shlatin, the Quattara depresion in the western desert, and the new roads between Farafra and Baharia oasis. Also marine geomagnetic survey have been applied for the first time in Naser lake. Misallat and Abu-Simble geomagnetic observatories have been used to reduce the field data to the Epoch 2010. During the field measurements, whenever possible, the old stations occupied by the previous observers have been re-occupied to determine the secular variations at these points. The geomagnetic anomaly maps, the normal geomagnetic field maps with their corresponding secular variation maps, the normal geomagnetic field equations of the geomagnetic elements (EGRF) and their corresponding secular variations equations, are outlined. The anomalous sites, as discovered from the anomaly maps are, only, mentioned. In addition, a correlation between the International Geomagnetic Reference Field (IGRF) 2010.0 and the Egyptian Geomagnetic Reference Field (EGRF) 2010 is indicated.

  1. Simultaneous single epoch satellite clock modelling in Global Navigation Satellite Systems

    Science.gov (United States)

    Thongtan, Thayathip

    In order to obtain high quality positions from navigation satellites, range errors have to be identified and either modelled or estimated. This thesis focuses on satellite clock errors, which are needed to be known because satellite clocks are not perfectly synchronised with navigation system time. A new approach, invented at UCL, for the simultaneous estimation, in a single epoch, of all satellite clock offsets within a Global Navigation Satellite System (GNSS) from range data collected at a large number of globally distributed ground stations is presented. The method was originally tested using only data from a limited number of GPS satellites and ground stations. In this work a total of 50 globally distributed stations and the whole GPS constellation are used in order to investigate more fully the capabilities of the method, in terms of both accuracy and reliability. A number of different estimation models have been tested. These include those with different weighting schemes, those with and without tropospheric bias parameters and those that include assumptions regarding prior knowledge of satellite orbits. In all cases conclusions have been drawn based on formal error propagation theory. Accuracy has been assessed largely through the sizes of the predicted satellite clock standard deviations and, in the case of simultaneously estimating satellite positions, their error ellipsoids. Both internal and external reliability have been assessed as these are important contributors to integrity, something that is essential for many practical applications. It has been found that the accuracy and reliability of satellite clock offsets are functions of the number of known ground station clocks and distance from them, quality of orbits and quality of range measurement. Also the introduction of tropospheric zenith delay parameters into the model reduces both accuracy and reliability by amounts depending on satellite elevation angles. (Abstract shortened by UMI.)

  2. Epoch of reionization 21 cm forecasting from MCMC-constrained semi-numerical models

    Science.gov (United States)

    Hassan, Sultan; Davé, Romeel; Finlator, Kristian; Santos, Mario G.

    2017-06-01

    The recent low value of Planck Collaboration XLVII integrated optical depth to Thomson scattering suggests that the reionization occurred fairly suddenly, disfavouring extended reionization scenarios. This will have a significant impact on the 21 cm power spectrum. Using a semi-numerical framework, we improve our model from instantaneous to include time-integrated ionization and recombination effects, and find that this leads to more sudden reionization. It also yields larger H ii bubbles that lead to an order of magnitude more 21 cm power on large scales, while suppressing the small-scale ionization power. Local fluctuations in the neutral hydrogen density play the dominant role in boosting the 21 cm power spectrum on large scales, while recombinations are subdominant. We use a Monte Carlo Markov chain approach to constrain our model to observations of the star formation rate functions at z = 6, 7, 8 from Bouwens et al., the Planck Collaboration XLVII optical depth measurements and the Becker & Bolton ionizing emissivity data at z ˜ 5. We then use this constrained model to perform 21 cm forecasting for Low Frequency Array, Hydrogen Epoch of Reionization Array and Square Kilometre Array in order to determine how well such data can characterize the sources driving reionization. We find that the Mock 21 cm power spectrum alone can somewhat constrain the halo mass dependence of ionizing sources, the photon escape fraction and ionizing amplitude, but combining the Mock 21 cm data with other current observations enables us to separately constrain all these parameters. Our framework illustrates how the future 21 cm data can play a key role in understanding the sources and topology of reionization as observations improve.

  3. A High Reliability Survey of Discrete Epoch of Reionization Foreground Sources in the MWA EoR0 Field

    CERN Document Server

    Carroll, P A; Morales, M F; Barry, N; Beardsley, A P; Hazelton, B J; Jacobs, D C; Pober, J C; Sullivan, I S; Webster, R L; Bernardi, G; Bowman, J D; Briggs, F; Cappallo, R J; Corey, B E; de Oliveira-Costa, A; Dillon, J S; Emrich, D; Ewall-Wice, A; Feng, L; Gaensler, B M; Goeke, R; Greenhill, L J; Hewitt, J N; Hurley-Walker, N; Johnston-Hollitt, M; Kaplan, D L; Kasper, J C; Kim, HS; Kratzenberg, E; Lenc, E; Loeb, A; Lonsdale, C J; Lynch, M J; McKinley, B; McWhirter, S R; Mitchell, D A; Morgan, E; Neben, A R; Oberoi, D; Offringa, A R; Ord, S M; Paul, S; Pindor, B; Prabu, T; Procopio, P; Riding, J; Rogers, A E E; Roshi, A; Shankar, N Udaya; Sethi, S K; Srivani, K S; Subrahmanyan, R; Tegmark, M; Thyagarajan, Nithyanandan; Tingay, S J; Trott, C M; Waterson, M; Wayth, R B; Whitney, A R; Williams, A; Williams, C L; Wu, C; Wyithe, J S B

    2016-01-01

    Detection of the Epoch of Reionization HI signal requires a precise understanding of the intervening galaxies and AGN, both for instrumental calibration and foreground removal. We present a catalogue of 7394 extragalactic sources at 182 MHz detected in the RA=0 field of the Murchison Widefield Array Epoch of Reionization observation programme. Motivated by unprecedented requirements for precision and reliability we develop new methods for source finding and selection. We apply machine learning methods to self-consistently classify the relative reliability of 9490 source candidates. A subset of 7466 are selected based on reliability class and signal-to-noise ratio criteria. These are statistically cross-matched to four other radio surveys using both position and flux density information. We find 7369 sources to have confident matches, including 90 partially resolved sources that split into a total of 192 sub-components. An additional 25 unmatched sources are included as new radio detections. The catalogue sour...

  4. The Hydrogen Epoch of Reionization Array (HERA). Improvement of the antenna response with a matching network and scientific impacts

    CERN Document Server

    Fagnoni, Nicolas

    2016-01-01

    The Hydrogen Epoch of Reionization Array (HERA) is a new powerful radio-telescope, dedicated to the study of the early universe. Its main goal is to characterise the period of the universe where the first galaxies and stars started to form, by studying the evolution of the 21-cm emission signal from neutral hydrogen, during the Epoch of Reionization. In this article, we present an electromagnetic and electrical co-simulation of the antenna performed with CST. We focus our analysis on the characterisation of the chromatic effects caused by the antenna, in particular multiple reflections of the received signal between the feed and the dish. These reflections can have an important impact on the scientific results, and it is crucial to keep them as low as possible. Therefore, we are currently developing a matching circuit which aims to improve the impedance matching between the feed and the front end.

  5. Effects of Antenna Beam Chromaticity on Redshifted 21~cm Power Spectrum and Implications for Hydrogen Epoch of Reionization Array

    CERN Document Server

    Thyagarajan, Nithyanandan; DeBoer, David; Bowman, Judd; Ewall-Wice, Aaron; Neben, Abraham; Patra, Nipanjana

    2016-01-01

    Unaccounted for systematics from foregrounds and instruments can severely limit the sensitivity of current experiments from detecting redshifted 21~cm signals from the Epoch of Reionization (EoR). Upcoming experiments are faced with a challenge to deliver more collecting area per antenna element without degrading the data with systematics. This paper and its companions show that dishes are viable for achieving this balance using the Hydrogen Epoch of Reionization Array (HERA) as an example. Here, we specifically identify spectral systematics associated with the antenna power pattern as a significant detriment to all EoR experiments which causes the already bright foreground power to leak well beyond ideal limits and contaminate the otherwise clean EoR signal modes. A primary source of this chromaticity is reflections in the antenna-feed assembly and between structures in neighboring antennas. Using precise foreground simulations taking wide-field effects into account, we provide a framework to set cosmologica...

  6. Program and Portfolio Tradeoffs Under Uncertainty Using Epoch-Era Analysis: A Case Application to Carrier Strike Group Design

    Science.gov (United States)

    2015-05-01

    Program and Portfolio Tradeoffs Under Uncertainty Using Epoch-Era Analysis A Case Application to Carrier Strike Group Design Parker D. Vascik...Analysis: A Case Application to Carrier Strike Group Design 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...for Affordability • Case Application: Carrier Strike Group (CSG) seari.mit.edu 2 May 13-14, 2015 THE CHALLENGE OF DESIGN UNDER

  7. An Efficient Algorithm for On-the-Fly Data Race Detection Using an Epoch-Based Technique

    Directory of Open Access Journals (Sweden)

    Ok-Kyoon Ha

    2015-01-01

    Full Text Available Data races represent the most notorious class of concurrency bugs in multithreaded programs. To detect data races precisely and efficiently during the execution of multithreaded programs, the epoch-based FastTrack technique has been employed. However, FastTrack has time and space complexities that depend on the maximum parallelism of the program to partially maintain expensive data structures, such as vector clocks. This paper presents an efficient algorithm, called iFT, that uses only the epochs of the access histories. Unlike FastTrack, our algorithm requires O(1 operations to maintain an access history and locate data races, without any switching between epochs and vector clocks. We implement this algorithm on top of the Pin binary instrumentation framework and compare it with other on-the-fly detection algorithms, including FastTrack, which uses a state-of-the-art happens-before analysis algorithm. Empirical results using the PARSEC benchmark show that iFT reduces the average runtime and memory overhead to 84% and 37%, respectively, of those of FastTrack.

  8. A Machine-learning Approach to Measuring the Escape of Ionizing Radiation from Galaxies in the Reionization Epoch

    Science.gov (United States)

    Jensen, Hannes; Zackrisson, Erik; Pelckmans, Kristiaan; Binggeli, Christian; Ausmees, Kristiina; Lundholm, Ulrika

    2016-08-01

    Recent observations of galaxies at z≳ 7, along with the low value of the electron scattering optical depth measured by the Planck mission, make galaxies plausible as dominant sources of ionizing photons during the epoch of reionization. However, scenarios of galaxy-driven reionization hinge on the assumption that the average escape fraction of ionizing photons is significantly higher for galaxies in the reionization epoch than in the local universe. The NIRSpec instrument on the James Webb Space Telescope (JWST) will enable spectroscopic observations of large samples of reionization-epoch galaxies. While the leakage of ionizing photons will not be directly measurable from these spectra, the leakage is predicted to have an indirect effect on the spectral slope and the strength of nebular emission lines in the rest-frame ultraviolet and optical. Here, we apply a machine learning technique known as lasso regression on mock JWST/NIRSpec observations of simulated z = 7 galaxies in order to obtain a model that can predict the escape fraction from JWST/NIRSpec data. Barring systematic biases in the simulated spectra, our method is able to retrieve the escape fraction with a mean absolute error of {{Δ }}{f}{esc}≈ 0.12 for spectra with signal-to-noise ratio ≈ 5 at a rest-frame wavelength of 1500 Å for our fiducial simulation. This prediction accuracy represents a significant improvement over previous similar approaches.

  9. Line-of-Sight Anisotropies in the Cosmic Dawn and Epoch of Reionization 21-cm Power Spectrum

    Indian Academy of Sciences (India)

    Suman Majumdar; Kanan K. Datta; Raghunath Ghara; Rajesh Mondal; T. Roy Choudhury; Somnath Bharadwaj; Sk. Saiyad Ali; Abhirup Datta

    2016-12-01

    The line-of-sight direction in the redshifted 21-cm signal coming from the cosmic dawn and the epoch of reionization is quite unique in many ways compared to any other cosmological signal. Different unique effects, such as the evolution history of the signal, non-linear peculiar velocities of the matter etc. will imprint their signature along the line-of-sight axis of the observed signal. One of the major goals of the future SKA-LOW radio interferometer is to observe the cosmic dawn and the epoch of reionization through this 21-cm signal. It is thus important to understand how these various effects affect the signal for its actual detection and proper interpretation. For more than one and half decades, various groups in India have been actively trying to understand and quantify the different line-of-sight effects that are present in this signal through analytical models and simulations. In many ways the importance of this sub-field under 21-cm cosmology have been identified, highlighted and pushed forward by the Indian community. In this article, we briefly describe their contribution and implication of these effects in the context of the future surveys of the cosmic dawn and the epoch of reionization that will be conducted by the SKA-LOW.

  10. Constraining sub-Parsec Binary Supermassive Black Holes in Quasars with Multi-Epoch Spectroscopy. I. The General Quasar Population

    CERN Document Server

    Shen, Yue; Loeb, Abraham; Tremaine, Scott

    2013-01-01

    We perform a systematic search for sub-parsec binary supermassive black holes (BHs) in normal broad line quasars at z<0.8, using multi-epoch SDSS spectroscopy of the broad Hbeta line. Our working model is that: only one of the two BHs in the binary is active, and dynamically dominates its own broad line region (BLR); the inactive companion BH is orbiting at a distance of a few R_BLR, where R_BLR~0.01-0.1 pc is the BLR size. We search for the expected line-of-sight acceleration of the broad line velocity from binary orbital motion by cross-correlating SDSS spectra from two epochs separated by up to several years in the quasar restframe. Out of ~700 pairs of spectra for which we have good measurements of the velocity shift between two epochs (1-sigma error~40 km/s), we detect 28 systems with significant velocity shifts in broad Hbeta, among which seven are the best candidates for the hypothesized binaries. We use the distribution of the observed accelerations (mostly non-detections) to place constraints on t...

  11. Middle Cretaceous to Oligocene rise of the Middle American landbridge - documented by south-eastwards younging shallow water carbonates

    Science.gov (United States)

    Baumgartner-Mora, Claudia; Baumgartner, Peter O.; Barat, Flore

    2013-04-01

    -Nicoya fault line (Central Costa Rica) Late Cretaceous oceanic plateaus may represent actual outcrops of the trailing edge of the Caribbean Large Igneous Province (CLIP). These include the SE corner of the Herradura Promontory (Costa Rica) and the Azuero Plateau cropping out in Coiba, Sona and Azuero (Panama). CLIP formation triggered a new, E-dipping subduction zone and Campanian-Maastrichtian arc initiation on the CLIP edge. By middle to late Eocene times this Middle American Arc and forearc areas reached the photic zone leading to widespread formation of carbonate banks/ramps. They are dated by many Larger Foraminifera of the genera Amphistegina, Asterocyclina, Discocyclina, Euconoloides, Eofabiania, Fabiania, Gypsina, Helicolepidina, Heterostegina, , Lepidocyclina, Linderina, Neodiscocyclina, Nummulites, Operculina, Orthophragmina, Polylepidina, Proporocyclina, and Sphareogypsina. The first shallow carbonates that encroach on arc/forearc basements in Panama are dated as Late Eocene in Azuero and the Canal Basin and as Oligocene, dated by Lepidocyclina miraflorensis, L. giraudi, L. canellei around the Chucunaque Basin of Eastern Panama. Progressive shallowing of the trailing edge of the Caribbean plate from NW (middle/Late Cretaceous) to SE (Late Eocene-Oligocene) implies a growing restriction of the Atlantic - Caribbean - Pacific seaway that must have affected global circulation patterns, to be considered in palaeo-oceanographic/palaeo-climatic models of the Late Cretaceous -Tertiary.

  12. Nazca-South America interactions and the late Eocene-late Oligocene flat-slab episode in the central Andes

    Science.gov (United States)

    O'Driscoll, Leland J.; Richards, Mark A.; Humphreys, Eugene D.

    2012-04-01

    The most prominent features of the Andean range are the Altiplano and Puna plateaus, which were constructed by crustal shortening and uplift over the past ˜45 Myr. The early construction of these plateaus may have controlled subsequent growth of the orogen. Proposed models have suggested that an abrupt acceleration in relative motion between the Nazca plate and the South American plate at ˜30 Ma may have led to compression of the continent. However, the major plate motion change occurred at 25-23 Ma, and paleomagnetic rotations and crustal shortening of the Andean forearc require that the Arica Bend formed prior to about 25 Ma. Inferred history of flat-slab subduction along the Altiplano section of the Andean margin and the structure of the adjacent South American cratonic shield combine to suggest an alternate scenario, based partly upon geodynamic models of oceanic-continental plate interactions in subduction zones. We propose that central Andean tectonism may have been controlled by two distinct regimes of subduction: (1) oblique subduction along the central Andean margin during the late Eocene and Oligocene accompanied by downdip alignment with the center of the Amazonian Shield (flat-slab activity in this phase of orogenesis may have been caused by a combination of cratonic root enhanced tectonics and oceanic plateau subduction) and (2) an abrupt transition to trench-normal subduction after ˜25 Ma toward the more distal São Francisco Craton was accompanied by a return to normal angle subduction. Similar interactions are hypothesized to have occurred during the Laramide Orogeny in western North America.

  13. A new interpretation of the two-step δ18O signal at the Eocene-Oligocene boundary

    Directory of Open Access Journals (Sweden)

    H. A. Dijkstra

    2010-07-01

    Full Text Available The most marked step in the global climate transition from "Greenhouse" to "Icehouse" Earth occurred at the Eocene-Oligocene (E–O boundary, 33.7 Ma. Evidence for climatic changes comes from many sources, including the marine benthic δ18O record, showing an increase by 1.2–1.5‰ at this time. This positive excursion is characterised by two steps, separated by a plateau. The increase in δ18O values has been attributed to rapid glaciation of the Antarctic continent, previously ice-free. Simultaneous changes in the δ13C record are indicative of a greenhouse gas control on climate. Previous studies show that a decline in pCO2 beyond a certain threshold value may have initiated the growth of a Southern Hemispheric ice sheet. These studies were not able to conclusively explain the remarkable two-step profile in δ18O. Furthermore, they did not address the potential role of changes in ocean circulation in the E–O transition. Here a new interpretation of the δ18O signal is presented, based on model simulations using a simple coupled 8-box-ocean, 4-box-atmosphere model with an added land ice component. The model was forced with a slowly decreasing atmospheric carbon dioxide concentration. It is argued that the first step in the δ18O represents a shift in meridional overturning circulation from a Southern Ocean to a bipolar source of deep-water formation, which is associated with a cooling of the deep sea. This shift can be initiated by a small density perturbation in the model, although there is also a parameter regime for which the shift occurs spontaneously. The second step in the δ18O profile occurs due to a rapid glaciation of the Antarctic continent. This new interpretation is a robust outcome of our model and is in good agreement with proxy data.

  14. A new mechanism for the two-step δ18O signal at the Eocene-Oligocene boundary

    Directory of Open Access Journals (Sweden)

    A. S. von der Heydt

    2011-03-01

    Full Text Available The most marked step in the global climate transition from "Greenhouse" to "Icehouse" Earth occurred at the Eocene-Oligocene (E-O boundary, 33.7 Ma. Evidence for climatic changes comes from many sources, including the marine benthic δ18O record, showing an increase by 1.2–1.5‰ at this time. This positive excursion is characterised by two steps, separated by a plateau. The increase in δ18O values has been attributed to rapid glaciation of the Antarctic continent, previously ice-free. Simultaneous changes in the δ13C record are suggestive of a greenhouse gas control on climate. Previous modelling studies show that a decline in pCO2 beyond a certain threshold value may have initiated the growth of a Southern Hemispheric ice sheet. These studies were not able to conclusively explain the remarkable two-step profile in δ18O. Furthermore, they considered changes in the ocean circulation only regionally, or indirectly through the oceanic heat transport. The potential role of global changes in ocean circulation in the E-O transition has not been addressed yet. Here a new interpretation of the δ18O signal is presented, based on model simulations using a simple coupled 8-box-ocean, 4-box-atmosphere model with an added land ice component. The model was forced with a slowly decreasing atmospheric carbon dioxide concentration. It is argued that the first step in the δ18O record reflects a shift in meridional overturning circulation from a Southern Ocean to a bipolar source of deep-water formation, which is associated with a cooling of the deep sea. The second step in the δ18O profile occurs due to a rapid glaciation of the Antarctic continent. This new mechanism is a robust outcome of our model and is qualitatively in close agreement with proxy data.

  15. Stratigraphy, correlation, depositional setting, and geophysical characteristics of the Oligocene Snowshoe Mountain Tuff and Creede Formation in two cored boreholes

    Science.gov (United States)

    Larsen, Daniel; Nelson, Philip H.

    2000-01-01

    Core descriptions and geophysical logs from two boreholes (CCM-1 and CCM-2) in the Oligocene Snowshoe Mountain Tuff and Creede Formation, south-central Colorado, are used to interpret sedimentary and volcanic facies associations and their physical properties. The seven facies association include a mixed sequence of intracaldera ash-flow tuffs and breccias, alluvial and lake margin deposits, and tuffaceous lake beds. These deposits represent volcanic units related to caldera collapse and emplacement of the Snowshoe Mountain Tuff, and sediments and pyroclastic material deposited in the newly formed caldera basin, Early sedimentation is interpreted to have been rapid, and to have occurred in volcaniclastic fan environments at CCM-1 and in a variery of volcaniclastic fan, braided stream shallow lacustrine, and mudflat environments at CCM-2. After an initial period of lake-level rise, suspension settling, turbidite, and debris-flow sedimentation occurred in lacustrine slope and basin environments below wave base. Carbonate sedimentation was initially sporadic, but more continuous in the latter part of the recorded lake history (after the H fallout tuff). Sublacustrine-fan deposition occurred at CCM-1 after a pronounced lake-level fall and subsequent rise that preceded the H tuff. Variations in density, neutron, gamma-ray, sonic, and electrical properties of deposits penetrated oin the two holes reflect variations in lithology, porosity, and alteration. Trends in the geophysical properties of the lacustrine strata are linked to downhole changes in authigenic mineralology and a decrease in porosity interpreted to have resulted primarily from diagenesis. Lithological and geophysical characteristics provide a basis for correlation of the cores; however, mineralogical methods of correlation are hampered by the degree of diagenesis and alteration.

  16. An integrated paleomagnetic and magnetic anisotropy study of the Oligocene flysch from the Dukla nappe, Outer Western Carpathians, Poland

    Science.gov (United States)

    Kiss, Dániel; Márton, Emő; Tokarski, Antek K.

    2016-12-01

    The Dukla Nappe belongs to the Outer Western Carpathians, which suffered considerable shortening due to the convergence and collision of the European and African plates. In this paper we present new paleomagnetic and magnetic anisotropy results from the Polish part of the Dukla Nappe, based on 102 individually oriented cores from nine geographically distributed localities. Susceptibility measurements and mineralogy investigations showed that paramagnetic minerals are important contributors to susceptibility anisotropy (AMS). The AMS fabrics are related to deposition/compression (foliation) and weak tectonic deformation (lineation). The AARM fabric, that of the ferrimagnetic minerals, seems to be a less sensitive indicator of tectonic deformation than the AMS fabric. The inclination-only test points to the pre-folding age of the remanent magnetizations. Seven localities exhibit CCW rotation, a single one shows CW rotation. The CCW rotated paleomagnetic directions form two groups, one showing large, the other moderate CCW rotation. Previously published paleomagentic directions from the Slovak part of the same nappe exhibit smeared distribution between them. The declination of the overall-mean paleomagnetic direction for the Dukla nappe is similar to those observed in the neighbouring Magura and Silesian nappes, but it is of poorer quality. The AMS lineations at several localities are deviating more to the west from the present north than that of the local tectonic strikes. A possible explanation for this is that the AMS lineations were imprinted first, probably still in the Oligocene, while the sediments were soft (ductile deformation) and the folding and tilting took place during the CCW rotation.

  17. Geology and geochronology of the Tana Basin, Ethiopia: LIP volcanism, super eruptions and Eocene-Oligocene environmental change

    Science.gov (United States)

    Prave, A. R.; Bates, C. R.; Donaldson, C. H.; Toland, H.; Condon, D. J.; Mark, D.; Raub, T. D.

    2016-06-01

    New geological and geochronological data define four episodes of volcanism for the Lake Tana region in the northern Ethiopian portion of the Afro-Arabian Large Igneous Province (LIP): pre-31 Ma flood basalt that yielded a single 40Ar/39Ar age of 34.05 ± 0.54 / 0.56 Ma; thick and extensive felsic ignimbrites and rhyolites (minimum volume of 2- 3 ×103 km3) erupted between 31.108 ± 0.020 / 0.041 Ma and 30.844 ± 0.027 / 0.046 Ma (U-Pb CA-ID-TIMS zircon ages); mafic volcanism bracketed by 40Ar/39Ar ages of 28.90 ± 0.12 / 0.14 Ma and 23.75 ± 0.02 / 0.04 Ma; and localised scoraceous basalt with an 40Ar/39Ar age of 0.033 ± 0.005 / 0.005 Ma. The felsic volcanism was the product of super eruptions that created a 60-80 km diameter caldera marked by km-scale caldera-collapse fault blocks and a steep-sided basin filled with a minimum of 180 m of sediment and the present-day Lake Tana. These new data enable mapping, with a finer resolution than previously possible, Afro-Arabian LIP volcanism onto the timeline of the Eocene-Oligocene transition and show that neither the mafic nor silicic volcanism coincides directly with perturbations in the geochemical records that span that transition. Our results reinforce the view that it is not the development of a LIP alone but its rate of effusion that contributes to inducing global-scale environmental change.

  18. The bivalve Glycymeris planicostalis as a high-resolution paleoclimate archive for the Rupelian (Early Oligocene) of central Europe

    Science.gov (United States)

    Walliser, E. O.; Schöne, B. R.; Tütken, T.; Zirkel, J.; Grimm, K. I.; Pross, J.

    2015-04-01

    Current global warming is likely to result in a unipolar glaciated world with unpredictable repercussions on atmospheric and oceanic circulation patterns. These changes are expected to affect seasonal extremes and the year-to-year variability of seasonality. To better constrain the mode and tempo of the anticipated changes, climatologists require ultra-high-resolution proxy data of time intervals in the past, e.g., the Oligocene, during which boundary conditions were similar to those predicted for the near future. In the present paper, we assess whether such information can be obtained from shells of the long-lived bivalve mollusk Glycymeris planicostalis from the late Rupelian of the Mainz Basin, Germany. Our results indicate that the studied shells are pristinely preserved and provide an excellent archive for reconstructing changes of sea surface temperature on seasonal to interannual timescales. Shells of G. planicostalis grew uninterruptedly during winter and summer and therefore recorded the full seasonal temperature amplitude that prevailed in the Mainz Basin ~ 30 Ma. Absolute sea surface temperature data were reconstructed from δ18Oshell values assuming a δ18Owater signature that was extrapolated from coeval sirenian tooth enamel. Reconstructed values range between 12.3 and 22.0 °C and agree well with previous estimates based on planktonic foraminifera and shark teeth. However, temperatures during seasonal extremes vary greatly on interannual timescales. Mathematically re-sampled (i.e., corrected for uneven number of samples per annual increment) winter and summer temperatures averaged over 40 annual increments of three specimens equal 13.6 ± 0.8 and 17.3 ± 1.2 °C, respectively. Such high-resolution paleoclimate information can be highly relevant for numerical climate studies aiming to predict possible future climates in a unipolar glaciated or, ultimately, polar-ice-free world.

  19. Carbonate cements and grains in submarine fan sandstones—the Cergowa Beds (Oligocene, Carpathians of Poland) recorded by cathodoluminescence

    Science.gov (United States)

    Pszonka, Joanna; Wendorff, Marek

    2017-01-01

    The cathodoluminescence (CL) observations with cold cathode, supplemented by reconnaissance scanning electron microscope analyses, bring new data on petrology, provenance and diagenesis of the Oligocene-age Cergowa sandstones from the Outer Carpathians (SE Poland). The sandstones represent a variety of mass gravity flow sediments deposited on a submarine fan, which now forms a lenticular lithosome—a part of the Menilite Beds-Krosno Beds suite important for the hydrocarbons industry. The most common components of the Cergowa sandstones observed under the CL are carbonates—cement and grains that are mainly represented by lithoclasts. Carbonate cement is represented by five generations: brown (Cb), orange (Co), yellow (Cy), zoned (Cz) and black (Ck). Pore-filling Cb and Co calcite cements are interpreted as genetically related to eo- and mesodiagenetic phases. The mesodiagenetic phase is characterised by randomly distributed relatively large monocrystalline-zoned rhombs of dolomite cement (Cz) and ankerite/ferroan dolomite (Ck). The telodiagenetic phase is represented by pore-filling yellow calcite (Cy) that crystallised under the influence of suboxic meteoric waters. Lithoclasts represent six microfacies of carbonate rocks eroded in the source area, i.e. microbreccia, tectonised immature calcarenite/wacke, microsparite, sparite, biomicrosparite/packstone and dolostone. Pronounced indentations of terrigenous sand grains into intraclasts of packstone/biomicrosparite, coupled with commonly present similar packstone-type matrix, suggest that a significant part of matrix resulted from compaction of soft biomicrosparite grains. Terrigenous grains bound by calcite cement are commonly corroded by acidic diagenetic fluids, and partial or even complete replacement of silicates by calcite and clay minerals is illustrated here by feldspar grains. Substantial carbonate cementation has resulted in both the significant hardness and abrasion resistance of the Cergowa sandstones

  20. Palaeoenvironments during a terminal Oligocene or early Miocene transgression in a fluvial system at the southwestern tip of Africa

    Science.gov (United States)

    Roberts, D. L.; Neumann, F. H.; Cawthra, H. C.; Carr, A. S.; Scott, L.; Durugbo, E. U.; Humphries, M. S.; Cowling, R. M.; Bamford, M. K.; Musekiwa, C.; MacHutchon, M.

    2017-03-01

    A multi-proxy study of an offshore core in Saldanha Bay (South Africa) provides new insights into fluvial deposition, ecosystems, phytogeography and sea-level history during the late Paleogene-early Neogene. Offshore seismic data reveal bedrock topography, and provide evidence of relative sea levels as low as - 100 m during the Oligocene. 3D landscape reconstruction reveals hills, plains and an anastomosing river system. A Chattian or early Miocene age for the sediments is inferred from dinoflagellate taxa Distatodinium craterum, Chiropteridium lobospinosum, Homotryblium plectilum and Impagidinium paradoxum. The subtropical forest revealed by palynology includes lianas and vines, evergreen trees, palms and ferns, implying higher water availability than today, probably reduced seasonal drought and stronger summer rainfall. From topography, sedimentology and palynology we reconstruct Podocarpaceae-dominated forests, Proto-Fynbos, and swamp/riparian forests with palms and other angiosperms. Rhizophoraceae present the first South African evidence of Palaeogene/Neogene mangroves. Subtropical woodland-thicket with Combretaceae and Brachystegia (Peregrinipollis nigericus) probably developed on coastal plains. Some of the last remaining Gondwana elements on the sub-continent, e.g., Araucariaceae, are recorded. Charred particles signal fires prior to the onset of summer dry climate at the Cape. Marine and terrestrial palynomorphs, together with organic and inorganic geochemical proxy data, suggest a gradual glacio-eustatic transgression. The data shed light on Southern Hemisphere biogeography and regional climatic conditions at the Palaeogene-Neogene transition. The proliferation of the vegetation is partly ascribed to changes in South Atlantic oceanographic circulation, linked to the closure of the Central American Seaway and the onset of the Benguela Current 14 Ma.

  1. An integrated paleomagnetic and magnetic anisotropy study of the Oligocene flysch from the Dukla nappe, Outer Western Carpathians, Poland

    Directory of Open Access Journals (Sweden)

    Kiss Dániel

    2016-12-01

    Full Text Available The Dukla Nappe belongs to the Outer Western Carpathians, which suffered considerable shortening due to the convergence and collision of the European and African plates. In this paper we present new paleomagnetic and magnetic anisotropy results from the Polish part of the Dukla Nappe, based on 102 individually oriented cores from nine geographically distributed localities. Susceptibility measurements and mineralogy investigations showed that paramagnetic minerals are important contributors to susceptibility anisotropy (AMS. The AMS fabrics are related to deposition/compression (foliation and weak tectonic deformation (lineation. The AARM fabric, that of the ferrimagnetic minerals, seems to be a less sensitive indicator of tectonic deformation than the AMS fabric. The inclination-only test points to the pre-folding age of the remanent magnetizations. Seven localities exhibit CCW rotation, a single one shows CW rotation. The CCW rotated paleomagnetic directions form two groups, one showing large, the other moderate CCW rotation. Previously published paleomagentic directions from the Slovak part of the same nappe exhibit smeared distribution between them. The declination of the overall-mean paleomagnetic direction for the Dukla nappe is similar to those observed in the neighbouring Magura and Silesian nappes, but it is of poorer quality. The AMS lineations at several localities are deviating more to the west from the present north than that of the local tectonic strikes. A possible explanation for this is that the AMS lineations were imprinted first, probably still in the Oligocene, while the sediments were soft (ductile deformation and the folding and tilting took place during the CCW rotation.

  2. The palaeoclimatic significance of Eurasian Giant Salamanders (Cryptobranchidae: Zaissanurus, Andrias) - indications for elevated humidity in Central Asia during global warm periods (Eocene, late Oligocene warming, Miocene Climate Optimum)

    Science.gov (United States)

    Vasilyan, Davit; Böhme, Madelaine; Winklhofer, Michael

    2010-05-01

    Cryptobranchids represent a group of large sized (up to 1.8 m) tailed amphibians known since the Middle Jurassic (Gao & Shubin 2003). Two species are living today in eastern Eurasia: Andrias davidianus (China) and A. japonicus (Japan). Cenozoic Eurasian fossil giant salamanders are known with two genera and two or three species from over 30 localities, ranging from the Late Eocene to the Early Pliocene (Böhme & Ilg 2003). The Late Eocene species Zaissanurus beliajevae is restricted to the Central Asian Zaissan Basin (SE-Kazakhstan, 50°N, 85°E), whereas the Late Oligocene to Early Pliocene species Andrias scheuchzeri is distributed from Central Europe to the Zaissan Basin. In the latter basin the species occur during two periods; the latest Oligocene and the late Early to early Middle Miocene (Chkhikvadse 1982). Andrias scheuchzeri is osteological indistinguishable from both recent species, indicating a similar ecology (Westfahl 1958). To investigate the palaeoclimatic significance of giant salamanders we analyzed the climate within the present-day distribution area and at selected fossil localities with independent palaeoclimate record. Our results indicate that fossil and recent Andrias species occur in humid areas where the mean annual precipitation reach over 900 mm (900 - 1.300 mm). As a working hypothesis (assuming a similar ecology of Andrias and Zaissanurus) we interpret occurrences of both fossil Eurasian giant salamanders as indicative for humid palaeoclimatic conditions. Based on this assumption the Late Eocene, the latest Oligocene (late Oligocene warming) and the late Early to early Middle Miocene (Miocene Climatic Optimum) of Central Asia (Zaissan Basin) are periods of elevated humidity, suggesting a direct (positive) relationship between global climate and Central Asian humidity evolution. Böhme M., Ilg A. 2003: fosFARbase, www.wahre-staerke.com/ Chkhikvadze V.M. 1982. On the finding of fossil Cryptobranchidae in the USSR and Mongolia. Vertebrata

  3. Stratigraphy and palaeoenvironment of the Lower-``middle'' Oligocene units in the northern part of the Western Taurides (İncesu area, Isparta, Turkey)

    Science.gov (United States)

    Akkiraz, Mehmet Serkan; Akgün, Funda; Örçen, Sefer

    2011-01-01

    This study describes the stratigraphic and palaeoenvironmental significance of the Lower-"middle" Oligocene sediments based on the fauna from the Delikarkası Formation and the microflora from the İncesu Formation of the İncesu area (northern part of the western Taurides, Isparta province, Turkey). In the area, the Oligocene sediments show a regressive succession, which begins with the limestones of the Delikarkası Formation indicating marine conditions followed by conglomerates, sandstones and coaly mudstones of alluvial and fluvial (shallow marine-continental) origin. A well preserved foraminiferal assemblage including Nummulitesintermedius, Nummulitesvascus and Halkyardiamaxima proves an Early Oligocene age for the Delikarkası Formation. Due to palynological markers such as Boehlensipollishohli, Slowakipollishippophaëoides, Dicolpopolliskockelii, Magnolipollisneogenicus ssp. minor, Plicapollispseudoexcelsus, Caryapollenitessimplex and Intratriporopollenitesinstructus the İncesu Formation, which concordantly rests on the Delikarkası Formation, may be assigned to the Early-"middle" Oligocene. From the palynomorph assemblage, three zones have been recognised according to abundance of species. Zone 1 is characterized by predominance of C.simplex and Momipitespunctatus and rarely presence of tricolpate and tricolporate pollen. Zone 2 consists mainly of Inaperturopollenitesdubius, Leiotriletesmaxoides ssp. maximus, Verrucatosporitesfavus,Verrucatosporitesalienus and infrequently marine dinoflagellate cysts. Zone 3 is characterized by a high percentage of ferns such as Echinatisporis? chattensis and Polypodiaceoisporitessaxonicus. The presence of marine dinoflagellate cysts like Apectodinium sp. and Cleistosphaeridium sp., back-mangrove elements such as Acrostichumaureum and lepidocaryoid palms (e.g. Longapertitesdiscordis, Longapertitespunctatus and Longapertitespsilatus) in the sediments of the İncesu Formation imply coastal or near-coastal conditions

  4. Late Permian to Early Oligocene granitic magmatism of the Phan Si Pan uplift area, NW Vietnam: their relationship to Phanerozoic crustal evolution of Southwest China

    Science.gov (United States)

    Pham, T. T.; Shellnutt, G.

    2015-12-01

    The Phan Si Pan uplift area of NW Vietnam is a part of the Archean to Paleoproterozoic Yangtze Block, Southwest China. This area is of particular interest because it experienced a number of Phanerozoic crustal building events including the Emeishan Large Igneous Province, the India-Eurasia collision and Ailaoshan - Red River Fault displacement. In the Phan Si Pan uplift area, there are at least three different geochronological complexes, including: (1) Late Permian, (2) Eocene and (3) Early Oligocene. (1) The Late Permian silicic rocks are alkali ferroan A1-type granitic rocks with U/Pb ages of 251 ± 3 to 254 ± 3 Ma. The Late Permian silicic rocks of Phan Si Pan uplift area intrude the upper to middle crust and are considered to be part of the ELIP that was displaced during the India-Eurasian collision along the Ailaoshan-Red River Fault shear zone and adjacent structures (i.e. Song Da zone). Previous studies suggest the Late Permian granitic rocks were derived by fractional crystallization of high - Ti basaltic magma. (2) The Eocene rocks are alkali ferroan A1-type granites (U/Pb ages 49 ± 0.9 Ma) and are spatially associated with the Late Permian granitic rocks. The trace element ratios of this granite are similar to the Late Permian rocks (Th/Nb=0.2, Th/Ta = 2.5, Nb/U = 24, Nb/La =1.2, Sr/Y=1). The origin of the Eocene granite is uncertain but it is possible that it formed by fractional crystallization of a mafic magma during a period of extension within the Yangtze Block around the time of the India-Eurasia collision. (3) The Early Oligocene granite is characterized as a peraluminous within-plate granite with U/Pb ages of 31.3 ± 0.4 to 34 ± 1 Ma. The Early Oligocene granite has trace element ratios (Th/Nb = 2.1, Th/Ta = 22.6, Nb/U = 4.4, Nb/La = 0.4, Sr/Y = 60.4) similar to crust melts. The high Sr/Y ratio (Sr/Y = 20 - 205) indicates a lower crust source that was garnet-bearing. The Phan Si Pan uplift was neither a subduction zone nor an arc environment

  5. Eo-Oligocene Oil Shales of the Talawi, Lubuktaruk, and Kiliranjao Areas, West Sumatra: Are they potential source rocks?

    Directory of Open Access Journals (Sweden)

    M. Iqbal

    2014-12-01

    Full Text Available DOI:10.17014/ijog.v1i3.198To anticipate the increasing energy demand, additional data and information covering unconventional fossil fuels such as oil shale must be acquired to promote the usage of alternative energy sources to crude oil. The Talawi and Lubuktaruk regions situated within intra-montane Ombilin Basin, and the Kiliranjao assumed to be a small intra montane basin are occupied by Eo-Oligocene sediments of Sangkarewang and Kiliran Formations, respectively. Field activity, geochemical screening techniques, and organic petrographic analysis, supported by SEM mode, are methods used. Most of the oil shale sequence is typically of an organically rich-succession comprising predominantly well-bedded, laminated and fissile, brownish to dark grey organic-rich shale and mudstone rocks. The exinite macerals within oil shale comprise mainly Pediastrum-lamalginite with minor cutinite, resinite, liptodetrinite, sporinite, bituminite, and rare Botryococcus-telalginite. Therefore; the oil shale deposits can be described as “lamosites”. Minor vitrinite maceral is also recognized. TOC analysis on selected shale samples corresponds to a fair up to excellent category of source rock characterization. The hydrogen index (HI for all samples shows a range of values from 207 - 864, and pyrolysis yield (PY ranges from 2.67 to 79.72 mg HC/g rock. The kerogen is suggested to be of mixed Type II and Type I autochthonous materials such as alginite, with minor allochthonous substances. Oil samples collected appear to be positioned within more oil prone rather than gas prone. Thermal maturity of the oil shales gained from Tmax value and production index (PI tends to show immature to marginally/early mature stage. A consistency in the thermal maturity level results by using both Tmax and vitrinite reflectance value is recognized. On the basis of  SEM analysis, the oil shale has undergone a late eodiagenetic process. Thereby, overall, vitrinite reflectance

  6. Eo-Oligocene Oil Shales of the Talawi, Lubuktaruk, and Kiliranjao Areas, West Sumatra: Are they potential source rocks?

    Directory of Open Access Journals (Sweden)

    M. Iqbal

    2014-12-01

    Full Text Available DOI:10.17014/ijog.v1i3.198To anticipate the increasing energy demand, additional data and information covering unconventional fossil fuels such as oil shale must be acquired to promote the usage of alternative energy sources to crude oil. The Talawi and Lubuktaruk regions situated within intra-montane Ombilin Basin, and the Kiliranjao assumed to be a small intra montane basin are occupied by Eo-Oligocene sediments of Sangkarewang and Kiliran Formations, respectively. Field activity, geochemical screening techniques, and organic petrographic analysis, supported by SEM mode, are methods used. Most of the oil shale sequence is typically of an organically rich-succession comprising predominantly well-bedded, laminated and fissile, brownish to dark grey organic-rich shale and mudstone rocks. The exinite macerals within oil shale comprise mainly Pediastrum-lamalginite with minor cutinite, resinite, liptodetrinite, sporinite, bituminite, and rare Botryococcus-telalginite. Therefore; the oil shale deposits can be described as “lamosites”. Minor vitrinite maceral is also recognized. TOC analysis on selected shale samples corresponds to a fair up to excellent category of source rock characterization. The hydrogen index (HI for all samples shows a range of values from 207 - 864, and pyrolysis yield (PY ranges from 2.67 to 79.72 mg HC/g rock. The kerogen is suggested to be of mixed Type II and Type I autochthonous materials such as alginite, with minor allochthonous substances. Oil samples collected appear to be positioned within more oil prone rather than gas prone. Thermal maturity of the oil shales gained from Tmax value and production index (PI tends to show immature to marginally/early mature stage. A consistency in the thermal maturity level results by using both Tmax and vitrinite reflectance value is recognized. On the basis of  SEM analysis, the oil shale has undergone a late eodiagenetic process. Thereby, overall, vitrinite reflectance

  7. Morphologic and spectral investigation of exceptionally well-preserved bacterial biofilms from the Oligocene Enspel formation, Germany

    Science.gov (United States)

    Toporski, J. K. W.; Steele, A.; Westall, F.; Avci, R.; Martill, D. M.; McKay, D. S.

    2002-05-01

    The fossilised soft tissues of a tadpole and an associated coprolitic structure from the organic-rich volcanoclastic lacustrine Upper Oligocene Enspel sediments (Germany) were investigated using high-resolution imaging techniques and nondestructive in situ surface analysis. Total organic carbon analysis of the coprolite and the sediment revealed values of 28.9 and 8.9% respectively. The soft tissues from the tadpole and the coprolite were found to be composed of 0.5 to 1 μm-sized spheres and rod shapes. These features are interpreted as the fossil remains of bacterial biofilms consisting probably of heterotrophic bacteria and fossilised extracellular polymeric substances. They became fossilised while in the process of degrading the organic matter of the organism and the coprolite. Comparison with a modern marine biofilm revealed morphologic details identical to those observed in the fossil bacterial biofilms. Although the fossil biofilms on both macrofossils exhibited identical microtextures, their mode of preservation was inhomogeneous and varied between calcium phosphate and an as yet unidentified mineral phase consisting mainly of Si, Ca, Ti, P, and S, but also showing the presence of Mg, Al, and Fe. The coprolite consists purely of fossilised bacterial cells in a densely packed arrangement and associated fossilised extracellular polymeric substances. In addition to preliminary imaging and energy-dispersive X-ray analysis, both the fossil biofilms and the sediment were investigated by nondestructive in situ analysis using time of flight-secondary ion mass spectroscopy (ToF-SIMS). The mass spectra obtained on the coprolite in mass-resolved chemical mapping mode allowed the tentative identification of a number of organic secondary ion species. Some spectra appear to indicate the presence of bacterial hopanoids, but further work using standard techniques such as gas chromatography mass spectroscopy is needed to conclusively verify the presence of these substances

  8. Seismic slip at the base of the seismogenic layer along the exhumed extensional Oligocene Trois Villes Fault (Western Italian Alps)

    Science.gov (United States)

    Bistacchi, A.; Gatta, D.; Grizzetti, R.; Pennacchioni, G.

    2008-12-01

    The characterisation of fault rocks from exhumed faults is of paramount importance in fault and earthquake mechanics, since these rocks might provide constraints for models of seismic rupture initiation and propagation. The Trois Ville Fault is a major Oligocene extensional fault of the internal NW Alps, showing a cumulative displacement of c.a. 1 km evidenced by the offset boundary between Austroalpine gneisses (hangingwall) and Piedmont calcschists (footwall). Fault rocks consist of greenschist mylonitic gneiss (from an early stage), green indurated cataclasites, which constitute the 2-10 m thick core zone, and a thin (c.a. 10 cm) but extremely continuous layer of polycyclic pseudotachylytes which mark a strongly localised principal slipping zone. Pseudotachylytes lack distinctive features such as glass, microlites-spherulites, etc., but show a distinctive mineralogy of the melt-derived very fine-grained matrix, which is almost entirely constituted by monoclinic K-feldspar (low sanidine crystallised at ca. 990°C and partly ordered as far as 500- 700°C). This matrix is composed by very small crystals (0.5-5 μm), organised in aggregates and dendritic snowflake-like aggregates which might be explained by sintering or synneusis processes. The high crystallization T implies that pseudotachylytes derive from frictional melting of ultracataclasites (possibly incoherent, hence a fault gouge, at the time of deformation) near the brittle plastic transition (250- 300°C and 8-10 km). Hence, a new diagnostic criterion for frictional melting, based on crystallographic analysis, is introduced in this work. The melt mainly derived from phyllosilicates (muscovite and minor chlorite; Tmelt c.a. 750°C) and evidences of superheating may be envisaged (partial assimilation of albite and quartz; T > c.a. 1300°C). This points to a considerable seismic slip after the onset of frictional melting and to an efficient melting lubrication process in this kind of fault rocks

  9. Low-frequency interferometry: Design, calibration, and analysis towards detecting the epoch of reionization

    Science.gov (United States)

    Parsons, Aaron Robert

    Low-frequency interferometry provides us with the possibility of directly observing, via red-shifted 21cm emission, the ionization of the primordial intergalactic medium by radiation from the first stars and black holes. Building such interferometers presents daunting technical challenges related to the cross-correlation, calibration, and analysis of data from large antenna arrays with wide fields-of-view in an observing band below 200 MHz. Addressing cross-correlation data processing, I present a general-purpose correlator architecture that uses standard 10-Gbit Ethernet switches to pass data between flexible hardware modules containing Field Programmable Gate Array chips. These chips are programmed using open-source signal processing libraries developed to be flexible, scalable, and chip-independent. This work reduces the time and cost of implementing a wide range of signal processing systems, and facilitates upgrading to new generations of processing technology. This correlator architecture is supporting the incremental build-out of the Precision Array for Probing the Epoch of Reionization. Targeting calibration concerns, I present a filtering technique that can be applied to individual baselines of wide-bandwidth, wide-field interferometric data to geometrically select regions on the celestial sphere that contain primary calibration sources. The technique relies on the Fourier transformation of wide-band frequency spectra from a given baseline to obtain one-dimensional "delay images", and then the transformation of a time-series of delay images to obtain two-dimensional "delay/delayrate images." These filters are augmented by a one-dimensional, complex CLEAN algorithm has been developed to compensate for data-excision effects related to the removal of radio frequency interference. This approach allows CLEANed, source-isolated data to be used to isolate bandpass and primary beam gain functions. These techniques are applied to PAPER data as a demonstration of

  10. VizieR Online Data Catalog: Second epoch VLBA Calibrator Survey (VCS-II) (Gordon+, 2016)

    Science.gov (United States)

    Gordon, D.; Jacobs, C.; Beasley, A.; Peck, A.; Gaume, R.; Charlot, P.; Fey, A.; Ma, C.; Titov, O.; Boboltz, D.

    2016-07-01

    Six Very Long Baseline Array (VLBA) calibrator survey campaigns were run between 1994 and 2007 (VCS1, Beasley et al. 2002, cat. J/ApJS/141/13; VCS2, Fomalont et al. 2003, cat. J/AJ/126/2562; VCS3, Petrov et al. 2005, cat. J/AJ/129/1163; VCS4, Petrov et al. 2006, cat. J/AJ/131/1872; VCS5, Kovalev et al. 2007, cat. J/AJ/133/1236; VCS6, Petrov et al. 2008, cat. J/AJ/136/580) We report on the results of a second epoch VLBA Calibrator Survey campaign (VCS-II) in which 2400 VCS sources were re-observed in the X and S bands. The VLBA S/X (S band~2.3GHz and X band~8.6GHz) dual frequency system was used. We used the VLBA RDBE/Mark5C system, which has 16 32MHz channels and records 2 Gbits/s using 2 bit sampling. Due to S-band filters below 2200MHz and above 2400MHz at most of the VLBA antennas, and a broad area of RFI from SiriusXM satellites (2320-2345MHz), only four channels could be deployed in the S band (2220.0, 2252.0, 2284.0, and 2348.0MHz). The other 12 channels were deployed in the X band (8460.0, 8492.0, 8524.0, 8556.0, 8620.0, 8652.0, 8716.0, 8748.0, 8812.0, 8844.0, 8876.0, and 8908.0MHz). We set a target of 300 sources per session, or 2400 total sources for the 8 VLBA sessions. We selected all sources from the Goddard Space Flight Center (GSFC) S/X astrometric/geodetic catalog (available at http://gemini.gsfc.nasa.gov/solutions/ or by following the links at http://lupus.gsfc.nasa.gov/) between -50° and +90° decl. that had been observed in only 1 or 2 sessions as of mid 2013. This amounted to ~2060 sources. To fill out the list, we added ~340 additional sources that had been observed but not detected in the original VCS1-6 analysis. The eight schedules were run between 2014 January and 2015 March (VCS-II-A/BG219A on 2014 01/04 10:04-01/05 10:02; VCS-II-B/BG219B1 on 2014 05/31 17:12-06/01 17:05; VCS-II-D/BG219D on 2014 06/09 09:13-06/10 09:10; VCS-II-C/BG219C on 2014 08/05 13:03-08/06 13:00; VCS-II-E/BG219E on 2014 08/09 00:00-08/09 23:55; VCS-II-F/BG219F on 2014

  11. CREATIVITY OF V.G. RASPUTIN AND V.V. KILYAKOV: THE CONCEPT OF CONFRONTATION OF EPOCHS

    Directory of Open Access Journals (Sweden)

    K. I. CHICHKINA

    2015-01-01

    Full Text Available This article highlights the philosophical reflection of artistic parallels in the creative works of writers of modern Russian literature – V.V. Kilyakov and V.G. Rasputin by the example of selected works. The  tory "Farewell to Matyora" by V.G. Rasputin and the story "Restless" by V.V. Kilyakov vividly express the concept of confrontation of epochs when comparing the spiritual and moral tragedies of the protagonists. Replacement of the eternal human values by the pursuit of profits and material achievements has deprived people of spiritual ideals. Honor, duty, patriotism, faith in God, respect for elders are replaced by dishonesty, vanity, immorality, trample of holy truths, and wastefulness in the pursuit of wealth. An unbreakable wall of misunderstanding and denial has appeared between the moral and immoral epochs. The idea of the compared works is not only to show this gap and its depth. The authors' position is clear - they cannot accept what is happening, and by their works they try to encourage the young generation to look back into the past. The objective of this article is to denote the concept of confrontation of epochs in the story by V.V. Kilyakov and to draw a parallel with the work by V.G. Rasputin in the context of spiritual and moral contradictions of villages and cities.

  12. Multiple Epoch Analysis of the Guitar Nebula and B2224+65 at Optical, X-Ray, and Radio Wavelengths

    Science.gov (United States)

    Gautam, Abhimat; Chatterjee, S.; Cordes, J. M.; Deller, A. T.; LAZIO, J.

    2013-01-01

    The Guitar Nebula is created by the interaction of the pulsar B2224+65 with the interstellar medium. We present multi-epoch observations of the nebula with the Hubble Space Telescope (HST) and the Chandra X-Ray Observatory (CXO), along with preliminary astrometric observations of B2224+65 with the Very Long Baseline Array (VLBA). The Guitar Nebula was observed in H-alpha by HST with WFPC2 (1994, 2001) and ACS (2006). The tip of the nebula head has expanded along the proper motion vector of the pulsar. Meanwhile, the sides and back of the head appear to be confined, possibly due to a density gradient in the ISM. Observations with CXO ACIS reveal an X-ray jet whose tip is coincident with the location of the pulsar, but at an angle of ~118° from the proper motion vector with a length of ~2 arcmin. Using data from 2000 and 2006, we imaged the jet at 0.3--10 keV. We did not find significant differences in the jet location or morphology between the two epochs, but our results are limited by the observation signal-to-noise ratio. PSR B2224+65 is one of the targets of PSRπ, an ongoing VLBA campaign to measure pulsar proper motions and parallaxes. When completed in 2013, PSRπ will provide both a distance and transverse velocity for PSR B2224+65 with very high precision. Based on a preliminary analysis of 5 epochs already observed, we confirm that the proper motion of the nebula tip measured with HST matches the pulsar proper motion measured with the VLBA. This project was conducted at Cornell University’s Astronomy REU program, with funding provided by the NSF.

  13. Basic Geomagnetic Network of the Republic of Croatia 2004 – 2012, with Geomagnetic Field Maps for 2009.5 epoch

    Directory of Open Access Journals (Sweden)

    Mario Brkić

    2013-12-01

    Full Text Available After more than half a century, scientific book Basic Geomagnetic Network of the Republic of Croatia 2004 – 2012, with Geomagnetic Field Maps for 2009.5 epoch describes the recent geomagnetic field on Croatian territory. A review of research in the past decade as well as the original solutions makes the book a document of contribution to geodesy and geomagnetism in Croatia.The book’s introduction gives an overview of two centuries of history and the strategic, security, economic and scientific significance of knowing the geomagnetic field on the Croatian territory. All the activities related to the updating of the geomagnetic information, which took place in the last decade, signified a big step toward the countries where geomagnetic survey is a mature scientific and technical discipline, and a scientific contribution to understanding of the nature of the Earth's magnetism.The declination, inclination and total intensity maps (along with the normal annual changes for the epoch 2009.5 are given in the Appendix. The book Basic Geomagnetic Network of the Republic of Croatia 2004 – 2012, with Geomagnetic Field Maps for 2009.5 epoch (ISBN 978-953-293-521-9 is published by the State Geodetic Administration of the Republic of Croatia. Beside editor in chief, M. Brkić, the authors are: E. Vujić, D. Šugar, E. Jungwirth, D. Markovinović, M. Rezo, M. Pavasović, O. Bjelotomić, M. Šljivarić, M. Varga and V. Poslončec-Petrić. The book contains 48 pages and 3 maps, and is published in 200 copies. CIP record is available in digital catalogue of the National and University Library in Zagreb under number 861937.

  14. The phenomenon of literature images transformation into musical images and paradigmal images of corresponding epochs (philosophy of history analysis

    Directory of Open Access Journals (Sweden)

    M. V. Masayev

    2014-01-01

    The author comes to the conclusion that the images of the M. A. Sholokhov’s novels «Quit Waves of Don» and «Newly­ploughed virgin soil» and short story «Destiny of the man» having become musical images of the I. I. Dzerzhinsky’s operas «Quit Waves of Don», «Newly­ploughed virgin soil», «Destiny of the man» and «Grigoriy Melekhov», turned into real paradigmal symbols of the epochs of the civil war, collectivization and the Great Patriotic War.

  15. VizieR Online Data Catalog: 2nd Epoch Molonglo Galactic Plane Survey, MGPS-2 (Murphy+, 2007)

    Science.gov (United States)

    Murphy, T.; Mauch, T.; Green, A.; Hunstead, R. W.; Piestrzynska, B.; Kels, A. P.; Sztajer, P.

    2007-08-01

    The second epoch Molonglo Galactic Plane Survey (MGPS-2) was carried out at 843MHz with the Molonglo Observatory Synthesis Telescope (MOST) in its upgraded wide-field capability. The survey consists of 4.3x4.3{deg} mosaic images with a 45x45"cosec{delta} restoring beam. It covers the range |b|method (described in the associated publication) to remove extended sources from the catalogue. Positions in the catalogue are accurate to 1-2". See http://www.astrop.physics.usyd.edu.au/mosaics for access to the mosaic images. (1 data file).

  16. VizieR Online Data Catalog: 2nd Epoch Molonglo Galactic Plane Survey (MGPS-2) (Murphy+, 2007)

    Science.gov (United States)

    Murphy, T.; Mauch, T.; Green, A.; Hunstead, R. W.; Piestrzynska, B.; Kels, A. P.; Sztajer, P.

    2007-08-01

    The MGPS-2 (second epoch Molonglo Galactic Plane Survey) was carried out with the Molonglo Observatory Synthesis Telescope at a frequency of 843MHz and with a restoring beam of 45"x45"csd|{delta}|, making it he highest resolution large scale radio survey of the southern Galactic plane. It covers the range |b|method (described in the associated publication) to remove extended sources from the catalogue. Positions in the catalogue are accurate to 1-2". See http://www.astrop.physics.usyd.edu.au/mosaics for access to the mosaic images. (1 data file).

  17. Probing neutrino physics with a self-consistent treatment of the weak decoupling, nucleosynthesis, and photon decoupling epochs

    CERN Document Server

    Grohs, E; Kishimoto, C T; Paris, M W

    2015-01-01

    We show that a self-consistent and coupled treatment of the weak decoupling, big bang nucleosynthesis, and photon decoupling epochs can be used to provide new insights and constraints on neutrino sector physics from high-precision measurements of light element abundances and cosmic microwave background observables. Implications of beyond-standard-model physics in cosmology, especially within the neutrino sector, are assessed by comparing predictions against five observables: the baryon energy density, helium abundance, deuterium abundance, effective number of neutrinos, and sum of the light neutrino mass eigenstates. We give examples for constraints on dark radiation, neutrino rest mass, lepton numbers, and scenarios for light and heavy sterile neutrinos.

  18. Non-parametric Data Analysis of Low-latitude Auroras and Naked-eye Sunspots in the Medieval Epoch

    Science.gov (United States)

    Bekli, Mohamed Reda; Zougab, Nabil; Belabbas, Abdelmoumene; Chadou, Ilhem

    2017-04-01

    We have studied solar activity by analyzing naked-eye sunspot observations and aurorae borealis observed at latitudes below 45°. We focused on the medieval epoch by considering the non-telescopic observations of sunspots from AD 974 to 1278 and aurorae borealis from AD 965 to 1273 that are reported in several Far East historical sources, primarily in China and Korea. After setting selection rules, we analyzed the distribution of these individual events following the months of the Gregorian calendar. In December, an unusual peak is observed with data recorded in both China and Japan, but not within Korean data.

  19. Oligocene sivaladapid primate from the Bugti Hills (Balochistan, Pakistan) bridges the gap between Eocene and Miocene adapiform communities in Southern Asia.

    Science.gov (United States)

    Marivaux, Laurent; Welcomme, Jean-Loup; Ducrocq, Stéphane; Jaeger, Jean-Jacques

    2002-04-01

    A new species of Guangxilemur (Sivaladapidae, Adapiformes) is described from the early Oligocene Chitarwata Formation (Bugti Member) of the Bugti Hills, Sulaiman geological Province, Balochistan, Pakistan. Guangxilemur singsilai n. sp. provides further diagnostic morphological characters from its newly described upper and lower dentitions, confirming its intermediate phylogenetic position between Eocene and Miocene Asian sivaladapid adapiforms. G. singsilai possesses moderately developed shearing and puncturing molar features and maintains lingual cusps on upper molars as in Eocene hoanghoniines; in contrast, it possesses a typical molariform P(4) as in Miocene sivaladapines. The important paleogeographic changes that have affected South Asia during the Tertiary (related to the collision between the Indian and Eurasian Plates) have played a critical role in reforming circulation and climatic differentiation. The presence in Pakistan of an unique and well-diversified Oligocene primate fauna, clearly demonstrates that South Asia maintained favourable environmental conditions during the middle Caenozoic global climatic deterioration that coincides with drastic changes in faunal structure on the whole Holarctic Province, including the extinction of adapiform primates.

  20. Provenance of late Oligocene to quaternary sediments of the Ecuadorian Amazonian foreland basin as inferred from major and trace element geochemistry and Nd-Sr isotopic composition

    Science.gov (United States)

    Roddaz, Martin; Christophoul, Frédéric; Burgos Zambrano, José David; Soula, Jean-Claude; Baby, Patrice

    2012-08-01

    Oligocene to Quaternary deposits from the Oriente Amazonian foreland basin (Ecuador and Peru) were analyzed for major and trace element geochemistry (46 and 32 samples respectively) and Nd-Sr isotopic systematics (n = 10). Chemical Index of Alteration values lower than those of other Amazonian foreland basin sediments and scattering along the AK join in the A-CN-K diagram indicate that the Oriente foreland basin has been continuously fed by poorly to moderately weathered sediments having an overall Andesitic composition since the Oligocene. Chemical ratios such as Cr/Th and Th/Sc as well as Eu anomaly and Nd-Sr isotopic compositions indicate that most of the analyzed sediments contained a greater proportion of volcanic arc rock material than the other Amazonian foreland basin sediments. When compared with the older sediments The Quaternary sediments are characterized by a greater contribution of the volcanic arc source. The composition of the sediments deposited in the Ecuadorian Amazonian foreland basin is mainly controlled by geodynamic processes. We suspect the Late Pliocene-Pleistocene subduction of the Carnegie ridge to be responsible for the back arc volcanism feeding the Amazonian foreland with more basic materials. Input of young Ecuadorian volcanic rocks may explain the difference in Sr and Nd isotopic ratios of suspended sediments between the Solimoes and the Madeira rivers.

  1. Occurrence and palaeoenvironmental significance of aromatic hydrocarbon biomarkers in Oligocene sediments from the Mallik 5L-38 Gas Hydrate Production Research Well (Canada)

    Energy Technology Data Exchange (ETDEWEB)

    Haberer, R.M.; Mangelsdorf, K.; Wilkes, H.; Horsfield, B. [Geoforschungszentrum Potsdam, Potsdam (Germany)

    2006-07-01

    The aromatic hydrocarbon biomarker distributions of thirty Oligocene sediment samples with different lithology (lignite, clay and sand) from the JAPEX/JNOC/GSC et al. Mallik 5L-38 Gas Hydrate Production Research Well, Canada, were analyzed using gas chromatography-mass spectrometry (GC-MS). The compositions vary with lithology, indicating a change in palaeoenvironmental conditions at the time of deposition. Aromatic diterpenoids of the abietane type are more abundant in the lignite samples than in the clay samples and represent a gymnosperm (e.g., conifer) dominated palaeovegetation. In contrast, in the clay samples aromatic triterpenoids are generally preserved as major constituents, indicating angiosperm dominated vegetation. The sand samples contain only minor amounts of aromatic terpenoids, but show a preference for diterpenoid gymnosperm markers. To recognise gymnosperm versus angiosperm dominated palaeoenvironments a new ratio, termed the angiosperm-gymnosperm aromatic ratio (AGAR), has been developed. Thus, the terpenoid distribution in the deltaic sediments provides information on the compositional changes in the plant community at the Mallik site (lignites) and the hinterland (clays) over time. Concomitantly, the changing dominance in the plant communities allows an insight into varying climatic conditions during the late Oligocene in the area.

  2. Climate and Biota across the Eocene-Oligocene transition at Site 1090: recent advances on calcareous nannofossils as paleoclimatic and dissolution proxy

    Science.gov (United States)

    Pea, Laura; Fioroni, Chiara; Villa, Giuliana; Persico, Davide; Bohaty, Steve

    2010-05-01

    The Eocene-Oligocene transition represents the biggest biotic turnover in the Cenozoic, involving both terrestrial and marine realms. In this study we present the results obtained by a quantitative analysis of late Eocene-early Oligocene (35.5- 33.1 Ma) calcareous nannofossil assemblages from ODP Site 1090 Hole B (Leg 177). This Hole is located on the southern flank of the Agulhas Ridge on the Subantarctic sector of the Atlantic Ocean (42°54'S), and lies along the boundary between the North Atlantic Deep Water and the Circumpolar Deep Water. Thanks to its position above the Carbonate Compensation Depth (3702 m), the nannofossil assemblage preservation is from poor to good in most of the section, even thought some intervals are barren. A well-preserved magnetostratigraphic signal along all of the section and nannofossil biostratigraphy provided the time framework essential for interpreting the assemblage variations. Within a high resolution biostratigraphic framework and through the comparison with bulk oxygen and carbon isotope datasets we attempt to reconstruct sea surface water temperature and trophic conditions, aimed to a late Eocene - early Oligocene paleoceanographic reconstruction for the South Atlantic. A marked change in the nannofossil assemblages is associated with the Oi-1 event: a nonlinear increase of cool-water taxa gives evidence as the evolution of this climatic event is more complex than previously estimated by calcareous nannofossils in the Southern Ocean (Villa et al., 2008). In fact cool-water taxa variation trend likely reflects the two distinct shifts (Step 1 and Step) recognised by Coxall et al. (2005) within the oxygen isotope shift .Step 1 falls in the uppermost part of magnetochron C13r, while the end of step 2 correlates with the base of Chron C13n (Channell et al., 2005). Furthermore, changes in nannofossil abundance and preservation suggest CCD depth fluctuations, showing a deepening near the Eocene/Oligocene boundary, as previously

  3. The Eocene-Oligocene sedimentary record in the Chesapeake Bay impact structure: Implications for climate and sea-level changes on the western Atlantic margin

    Science.gov (United States)

    Schulte, P.; Wade, B.S.; Kontny, A.; ,

    2009-01-01

    A multidisciplinary investigation of the Eocene-Oligocene transition in the International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) Eyreville core from the Chesapeake Bay impact basin was conducted in order to document environmental changes and sequence stratigraphic setting. Planktonic foraminifera and calcareous nannofossil biostratigraphy indicate that the Eyreville core includes an expanded upper Eocene (Biozones E15 to E16 and NP19/20 to NP21, respectively) and a condensed Oligocene-Miocene (NP24-NN1) sedimentary sequence. The Eocene-Oligocene contact corresponds to a =3-Ma-long hiatus. Eocene- Oligocene sedimentation is dominated by great diversity and varying amounts of detrital and authigenic minerals. Four sedimentary intervals are identified by lithology and mineral content: (1) A 30-m-thick, smectite- and illite-rich interval directly overlies the Exmore Formation, suggesting long-term reworking of impact debris within the Chesapeake Bay impact structure. (2) Subsequently, an increase in kaolinite content suggests erosion from soils developed during late Eocene warm and humid climate in agreement with data derived from other Atlantic sites. However, the kaolinite increase may also be explained by change to a predominant sediment input from outside the Chesapeake Bay impact structure caused by progradation of more proximal facies belts during the highstand systems tract of the late Eocene sequence E10.Spectral analysis based on gamma-ray and magnetic susceptibility logs suggests infl uence of 1.2 Ma low-amplitude oscillation of the obliquity period during the late Eocene. (3) During the latest Eocene (Biozones NP21 and E16), several lithological contacts (clay to clayey silt) occur concomitant with a prominent change in the mineralogical composition with illite as a major component: This lithological change starts close to the Biozone NP19/20-NP21 boundary and may correspond to sequence boundary E10-E11 as observed in

  4. Reconstructing paleoceanographic conditions during the Oligocene/Miocene Boundary using walled dinoflagellate cysts and TEX86: IODP Expedition 318, Wilkes Land, Antarctic margin

    Science.gov (United States)

    Bijl, Peter; Bruls, Anja; Hartman, Julian D.; Sangiorgi, Francesca; Peterse, Francien

    2017-04-01

    Wilkes land is potentially a sensitive sector of the East Antarctic Ice Sheet (EAIS), because Wilkes subglacial basin is largely below sea level. In light of this, understanding changes in ice volume in this sector of Antarctica during past episodes of warmth may help constrain future ice sheet melt in the region. Integrated Ocean Drilling Program Expedition 318 was intended to drill and recover from the Wilkes Land continental Margin to reconstruct the history of the East Antarctic ice sheet (EAIS). The integrated bio-magnetostratigraphic age model for IODP Site U1356 is quite robust for the entire stratigraphic record, but in the Oligocene-Miocene boundary interval, the details of the age model are somewhat elusive. Notably it is uncertain whether sediments dating back to the Mi-1 glaciation event, at the Oligocene-Miocene boundary, are represented in the record. This research presents a revised age model for the interval around the OMT and gives a paleoceanographic interpretation of Site U1356 based on dinocyst ecology and TEX86 biomarker proxy. The finding of the dinocyst species Edwardsiella sexispinosa provides for an additional dinocyst event, and revised the location of the OMT. Core 45R likely represents the base of the Miocene and Core 46R and Core 47R represents the late Oligocene between 23.23 to 25.1 Ma. The dinocyst ecology indicated varying intervals of mostly Protoperidinioid genera to mostly Gonyaulacoid genera, that represent high productivity conditions and oligotrophic conditions respectively. These changing ecological conditions have been related to the a changing upwelling regime along the Wilkes Land margin, which is connected to the polar wind field and positively correlated to the extent of the Antarctic ice sheets. Sea ice conditions are absent along the Wilkes Land margin throughout this part of the record, therefore deep-water formation would also have been reduced. The SST record provided by TEX86 biomarker proxy indicates a decreasing

  5. Mitochondrial DNA Detects a Complex Evolutionary History with Pleistocene Epoch Divergence for the Neotropical Malaria Vector Anopheles nuneztovari Sensu Lato

    Science.gov (United States)

    Scarpassa, Vera Margarete; Conn, Jan E.

    2011-01-01

    Cryptic species and lineages characterize Anopheles nuneztovari s.l. Gabaldón, an important malaria vector in South America. We investigated the phylogeographic structure across the range of this species with cytochrome oxidase subunit I (COI) mitochondrial DNA sequences to estimate the number of clades and levels of divergence. Bayesian and maximum-likelihood phylogenetic analyses detected four groups distributed in two major monophyletic clades (I and II). Samples from the Amazon Basin were clustered in clade I, as were subclades II-A and II-B, whereas those from Bolivia/Colombia/Venezuela were restricted to one basal subclade (II-C). These data, together with a statistical parsimony network, confirm results of previous studies that An. nuneztovari is a species complex consisting of at least two cryptic taxa, one occurring in Colombia and Venezuela and the another occurring in the Amazon Basin. These data also suggest that additional incipient species may exist in the Amazon Basin. Divergence time and expansion tests suggested that these groups separated and expanded in the Pleistocene Epoch. In addition, the COI sequences clearly separated An. nuneztovari s.l. from the closely related species An. dunhami Causey, and three new records are reported for An. dunhami in Amazonian Brazil. These findings are relevant for vector control programs in areas where both species occur. Our analyses support dynamic geologic and landscape changes in northern South America, and infer particularly active divergence during the Pleistocene Epoch for New World anophelines. PMID:22049039

  6. Major mergers are not significant drivers of star formation or morphological transformation around the epoch of peak cosmic star formation

    CERN Document Server

    Lofthouse, E K; Conselice, C J; Mortlock, A; Hartley, W

    2016-01-01

    We investigate the contribution of major mergers (mass ratios $>1:5$) to stellar mass growth and morphological transformations around the epoch of peak cosmic star formation ($z\\sim2$). We visually classify a complete sample of massive (M $>$ 10$^{10}$M$_{\\odot}$) galaxies at this epoch, drawn from the CANDELS survey, into late-type galaxies, major mergers, spheroids and disturbed spheroids which show morphological disturbances. Given recent simulation work, which indicates that recent ($<$0.3-0.4 Gyr) major-merger remnants exhibit clear tidal features in such images, we use the fraction of disturbed spheroids to probe the role of major mergers in driving morphological transformations. The percentage of blue spheroids (i.e. with ongoing star formation) that show morphological disturbances is only 21 $\\pm$ 4%, indicating that major mergers are not the dominant mechanism for spheroid creation at $z\\sim2$ - other processes, such as minor mergers or cold accretion are likely to be the main drivers of this proc...

  7. PROBING THE EPOCH OF PRE-REIONIZATION BY CROSS-CORRELATING COSMIC MICROWAVE AND INFRARED BACKGROUND ANISOTROPIES

    Energy Technology Data Exchange (ETDEWEB)

    Atrio-Barandela, F. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kashlinsky, A., E-mail: atrio@usal.es, E-mail: Alexander.Kashlinsky@nasa.gov [Observational Cosmology Lab, NASA Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States)

    2014-12-20

    The epoch of first star formation and the state of the intergalactic medium (IGM) at that time are not directly observable with current telescopes. The radiation from those early sources is now part of the cosmic infrared background (CIB) and, as these sources ionize the gas around them, the IGM plasma would produce faint temperature anisotropies in the cosmic microwave background (CMB) via the thermal Sunyaev-Zeldovich (TSZ) effect. While these TSZ anisotropies are too faint to be detected, we show that the cross-correlation of maps of source-subtracted CIB fluctuations from Euclid, with suitably constructed microwave maps at different frequencies, can probe the physical state of the gas during reionization and test/constrain models of the early CIB sources. We identify the frequency-combined, CMB-subtracted microwave maps from space- and ground-based instruments to show that they can be cross-correlated with the forthcoming all-sky Euclid CIB maps to detect the cross-power at scales ∼5'-60' with signal-to-noise ratios (S/Ns) of up to S/N ∼ 4-8 depending on the contribution to the Thomson optical depth during those pre-reionization epochs (Δτ ≅ 0.05) and the temperature of the IGM (up to ∼10{sup 4} K). Such a measurement would offer a new window to explore the emergence and physical properties of these first light sources.

  8. Major mergers are not significant drivers of star formation or morphological transformation around the epoch of peak cosmic star formation

    Science.gov (United States)

    Lofthouse, E. K.; Kaviraj, S.; Conselice, C. J.; Mortlock, A.; Hartley, W.

    2017-03-01

    We investigate the contribution of major mergers (mass ratios >1: 5) to stellar mass growth and morphological transformations around the epoch of peak cosmic star formation (z ∼ 2). We visually classify a complete sample of massive (M > 1010M⊙) galaxies at this epoch, drawn from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, into late-type galaxies, major mergers, spheroids and disturbed spheroids which show morphological disturbances. Given recent simulation work, which indicates that recent (clear tidal features in such images, we use the fraction of disturbed spheroids to probe the role of major mergers in driving morphological transformations. The percentage of blue spheroids (i.e. with ongoing star formation) that show morphological disturbances is only 21 ± 4 per cent, indicating that major mergers are not the dominant mechanism for spheroid creation at z ∼ 2 - other processes, such as minor mergers or cold accretion are likely to be the main drivers of this process. We also use the rest-frame U-band luminosity as a proxy for star formation to show that only a small fraction of the star formation budget (∼3 per cent) is triggered by major mergers. Taken together, our results show that major mergers are not significant drivers of galaxy evolution at z ∼ 2.

  9. The Effect of Variability on X-Ray Binary Luminosity Functions: Multiple Epoch Observations of NGC 300 with Chandra

    CERN Document Server

    Binder, Breanna; Williams, Benjamin F; Eracleous, Michael; Gaetz, Terrance J; Plucinsky, Paul P; Skillman, Evan D

    2016-01-01

    We have obtained three epochs of Chandra ACIS-I observations (totaling $\\sim$184 ks) of the nearby spiral galaxy NGC~300 to study the logN-logS distributions of its X-ray point source population down to $\\sim$2$\\times$10$^{-15}$ erg s$^{-1}$ cm$^{-2}$ in the 0.35-8 keV band (equivalent to $\\sim$10$^{36}$ erg s$^{-1}$). The individual epoch logN-logS distributions are best described as the sum of a background AGN component, a simple power law, and a broken power law, with the shape of the logN-logS distributions sometimes varying between observations. The simple power law and AGN components produce a good fit for "persistent" sources (i.e., with fluxes that remain constant within a factor of $\\sim$2). The differential power law index of $\\sim$1.2 and high fluxes suggest that the persistent sources intrinsic to NGC~300 are dominated by Roche lobe overflowing low mass X-ray binaries. The variable X-ray sources are described by a broken power law, with a faint-end power law index of $\\sim$1.7, a bright-end index ...

  10. EPOCH code simulation of a non-thermal distribution driven by neutral beam injection in a high-beta plasma

    Science.gov (United States)

    Necas, A.; Tajima, T.; Nicks, S.; Magee, R.; Clary, R.; Roche, T.; Tri Alpha Energy Team

    2016-10-01

    In Tri Alpha Energy's C-2U experiment, advanced beam-driven field-reversed configuration (FRC) plasmas were sustained via tangential neutral beam injection. The dominant fast ion population made a dramatic impact on the overall plasma performance. To explain an experimentally observed anomalous neutron signal (100x thermonuclear), we use EPOCH PIC code to simulate possible beam driven non-destructive instabilities that transfer energy from fast ions to the plasma, causing phase space bunching. We propose that the hydrogen beam ion population drives collective modes in the deuterium target plasma, giving rise to the instability and increased fusion rate. The instability changes character from electrostatic in the low beta edge to fully electromagnetic in the core, with an associated reduction in growth rates. The DD reactivity enhancement is calculated using a two-body correlation function and compared to the experimentally observed neutron yield. The high-energy tails in the distributions of the plasma deuterons and beam protons are observed via a mass-resolving Neutral Particle Analyzer (NPA) diagnostic. This observation is qualitatively consistent with EPOCH simulation of the beam-plasma instability.

  11. The Algorithm of Single-epoch Integer Ambiguity Resolution between Middle-range BDS Network RTK Reference Stations

    Directory of Open Access Journals (Sweden)

    ZHU Huizhong

    2016-01-01

    Full Text Available The algorithm of double frequency carrier phase integer ambiguity resolution between middle-range reference stations at single-epoch is proposed. The ambiguity candidates of B1 frequency and B2 frequency carrier phase are selected by linear relationship between carrier phase ambiguities of B1 frequency and B2 frequency carrier phase. The double difference ionosphere delay errors can be calculated by the ambiguity candidates of double frequency carrier phase. Then the linear calculation model of double difference ionosphere delay errors can be established by the double difference ionosphere delay errors according to the spatial relationship between the ionosphere delay errors of each satellites on reference stations. And the ambiguities of B1 frequency and B2 frequency carrier phase are searched and fixed in the establishing of the linear calculation model of double difference ionosphere delay errors. This algorithm is tested by the data of BDS CORS network. The results indicate that the double difference integer ambiguity between reference stations can be fixed at single-epoch, and this algorithm avoids the effect of cycle clips.

  12. Effects of Antenna Beam Chromaticity on Redshifted 21 cm Power Spectrum and Implications for Hydrogen Epoch of Reionization Array

    Science.gov (United States)

    Thyagarajan, Nithyanandan; Parsons, Aaron R.; DeBoer, David R.; Bowman, Judd D.; Ewall-Wice, Aaron M.; Neben, Abraham R.; Patra, Nipanjana

    2016-07-01

    Unaccounted for systematics from foregrounds and instruments can severely limit the sensitivity of current experiments from detecting redshifted 21 cm signals from the Epoch of Reionization (EoR). Upcoming experiments are faced with a challenge to deliver more collecting area per antenna element without degrading the data with systematics. This paper and its companions show that dishes are viable for achieving this balance using the Hydrogen Epoch of Reionization Array (HERA) as an example. Here, we specifically identify spectral systematics associated with the antenna power pattern as a significant detriment to all EoR experiments which causes the already bright foreground power to leak well beyond ideal limits and contaminate the otherwise clean EoR signal modes. A primary source of this chromaticity is reflections in the antenna-feed assembly and between structures in neighboring antennas. Using precise foreground simulations taking wide-field effects into account, we provide a generic framework to set cosmologically motivated design specifications on these reflections to prevent further EoR signal degradation. We show that HERA will not be impeded by such spectral systematics and demonstrate that even in a conservative scenario that does not perform removal of foregrounds, HERA will detect the EoR signal in line-of-sight k-modes, {k}\\parallel ≳ 0.2 h Mpc-1, with high significance. Under these conditions, all baselines in a 19-element HERA layout are capable of detecting EoR over a substantial observing window on the sky.

  13. A multi-resolution, multi-epoch low radio frequency survey of the Kepler K2 mission Campaign 1 field

    CERN Document Server

    Tingay, S J; Wayth, R B; Intema, H; Jagannathan, P; Mooley, K

    2016-01-01

    We present the first dedicated radio continuum survey of a Kepler K2 mission field, Field 1 covering the North Galactic Cap. The survey is wide field, contemporaneous, multi-epoch, and multi-resolution in nature and was conducted at low radio frequencies between 140 and 200 MHz. The multi-epoch and ultra wide field (but relatively low resolution) part of the survey was provided by 15 nights of observation with the Murchison Widefield Array (MWA) over a period of approximately a month, contemporaneous with K2 observations of the field. The multi-resolution aspect of the survey was provided by the low resolution (4') MWA imaging, complemented by non-contemporaneous but much higher resolution (20") observations using the Giant Metrewave Radio Telescope (GMRT). The survey is therefore sensitive to the details of radio structures across a wide range of angular scales. Consistent with other recent low radio frequency surveys, no significant radio transients or variables were detected in the survey. The resulting so...

  14. New Limits on Polarized Power Spectra at 126 and 164 MHz: Relevance to Epoch of Reionization Measurements

    CERN Document Server

    Moore, David; Parsons, Aaron; Ali, Zaki; Bradley, Richard; Carilli, Chris; DeBoer, David; Dexter, Matthew; Gugliucci, Nicole; Jacobs, Daniel; Klima, Pat; Liu, Adrian; MacMahon, David; Manley, Jason; Pober, Jonathan; Stefan, Irina; Walbrugh, William

    2015-01-01

    Polarized foreground emission is a potential contaminant of attempts to measure the fluctuation power spectrum of highly redshifted 21 cm H{\\sc i} emission from the epoch of reionization, yet observational constraints on the level of polarized emission are poor. Using the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER), we present the first limits on the power spectra of all four Stokes parameters in two frequency bands, centered at 126 MHz ($z=10.3$) and 164 MHz ($z=7.66$). This data comes from from a three-month observing campaign of a 32-antenna deployment, for which unpolarized power spectrum results have been reported at $z=7.7$ (Parsons et al 2014) and $7.5 < z < 10.5$ (Jacobs et al 2014). The power spectra in this paper are processed in the same way, and show no definitive detection of polarized power. The limits are sufficiently low that we are able to show that the excess unpolarized power reported in those works is not due to leakage of Faraday-rotated polarized ...

  15. The merger rates and sizes of galaxies across the peak epoch of star formation from the HiZELS survey

    CERN Document Server

    Stott, John P; Smail, Ian; Bower, Richard; Best, Philip N; Geach, James E

    2013-01-01

    We use the HiZELS narrow-band H-alpha survey in combination with CANDELS, UKIDSS and WIRDS near-infrared imaging, to investigate the morphologies, merger rates and sizes of a sample of H-alpha emitting galaxies in the redshift range z=0.40 - 2.23, an epoch encompassing the rise to the peak of the star formation rate density. Merger rates are estimated from space- and ground-based imaging using the M20 coefficient. To account for the increase in the specific star-formation rate (sSFR) of the star forming `main-sequence' with redshift, we normalise the star-formation rate of galaxies at each epoch to the typical value derived from the H-alpha luminosity function. Once this trend in sSFR is removed we see no evidence for an increase in the number density of star-forming galaxies or the merger rate with redshift. We thus conclude that neither is the main driver of the enhanced star-formation rate density at z=1-2, with secular processes such as instabilities within efficiently fuelled, gas-rich discs or multiple ...

  16. Superposed epoch study of ICME sub-structures near Earth and their effects on galactic cosmic rays

    CERN Document Server

    Masías-Meza, J J; Démoulin, P; Rodriguez, L; Janvier, M

    2016-01-01

    Interplanetary coronal mass ejections (ICMEs) are the interplanetary manifestations of solar eruptions. The overtaken solar wind forms a sheath of compressed plasma at the front of ICMEs. Magnetic clouds (MCs) are a subset of ICMEs with specific properties (e.g. the presence of a flux rope). When ICMEs pass near Earth, ground observations indicate that the flux of galactic cosmic rays (GCRs) decreases. The main aims of this paper are to find: common plasma and magnetic properties of different ICME sub-structures, and which ICME properties affect the flux of GCRs near Earth. We use a superposed epoch method applied to a large set of ICMEs observed \\insitu\\ by the spacecraft ACE, between 1998 and 2006. We also apply a superposed epoch analysis on GCRs time series observed with the McMurdo neutron monitors. We find that slow MCs at 1 AU have on average more massive sheaths. We conclude that it is because they are more effectively slowed down by drag during their travel from the Sun. Slow MCs also have a more sym...

  17. THE PRECISION AND ACCURACY OF EARLY EPOCH OF REIONIZATION FOREGROUND MODELS: COMPARING MWA AND PAPER 32-ANTENNA SOURCE CATALOGS

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, Daniel C.; Bowman, Judd [School of Space and Earth Exploration, Arizona State University, Tempe, AZ (United States); Aguirre, James E., E-mail: daniel.c.jacobs@asu.edu [Department of Physics and Astronomy, University of Pennsylvania, 209 S. 33rd Street, Philadelphia, PA (United States)

    2013-05-20

    As observations of the Epoch of Reionization (EoR) in redshifted 21 cm emission begin, we assess the accuracy of the early catalog results from the Precision Array for Probing the Epoch of Reionization (PAPER) and the Murchison Wide-field Array (MWA). The MWA EoR approach derives much of its sensitivity from subtracting foregrounds to <1% precision, while the PAPER approach relies on the stability and symmetry of the primary beam. Both require an accurate flux calibration to set the amplitude of the measured power spectrum. The two instruments are very similar in resolution, sensitivity, sky coverage, and spectral range and have produced catalogs from nearly contemporaneous data. We use a Bayesian Markov Chain Monte Carlo fitting method to estimate that the two instruments are on the same flux scale to within 20% and find that the images are mostly in good agreement. We then investigate the source of the errors by comparing two overlapping MWA facets where we find that the differences are primarily related to an inaccurate model of the primary beam but also correlated errors in bright sources due to CLEAN. We conclude with suggestions for mitigating and better characterizing these effects.

  18. A high reliability survey of discrete Epoch of Reionization foreground sources in the MWA EoR0 field

    Science.gov (United States)

    Carroll, P. A.; Line, J.; Morales, M. F.; Barry, N.; Beardsley, A. P.; Hazelton, B. J.; Jacobs, D. C.; Pober, J. C.; Sullivan, I. S.; Webster, R. L.; Bernardi, G.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Corey, B. E.; de Oliveira-Costa, A.; Dillon, J. S.; Emrich, D.; Ewall-Wice, A.; Feng, L.; Gaensler, B. M.; Goeke, R.; Greenhill, L. J.; Hewitt, J. N.; Hurley-Walker, N.; Johnston-Hollitt, M.; Kaplan, D. L.; Kasper, J. C.; Kim, HS.; Kratzenberg, E.; Lenc, E.; Loeb, A.; Lonsdale, C. J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morgan, E.; Neben, A. R.; Oberoi, D.; Offringa, A. R.; Ord, S. M.; Paul, S.; Pindor, B.; Prabu, T.; Procopio, P.; Riding, J.; Rogers, A. E. E.; Roshi, A.; Shankar, N. Udaya; Sethi, S. K.; Srivani, K. S.; Subrahmanyan, R.; Tegmark, M.; Thyagarajan, Nithyanandan; Tingay, S. J.; Trott, C. M.; Waterson, M.; Wayth, R. B.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wu, C.; Wyithe, J. S. B.

    2016-10-01

    Detection of the epoch of reionization H I signal requires a precise understanding of the intervening galaxies and AGN, both for instrumental calibration and foreground removal. We present a catalogue of 7394 extragalactic sources at 182 MHz detected in the RA = 0 field of the Murchison Widefield Array Epoch of Reionization observation programme. Motivated by unprecedented requirements for precision and reliability we develop new methods for source finding and selection. We apply machine learning methods to self-consistently classify the relative reliability of 9490 source candidates. A subset of 7466 are selected based on reliability class and signal-to-noise ratio criteria. These are statistically cross-matched to four other radio surveys using both position and flux density information. We find 7369 sources to have confident matches, including 90 partially resolved sources that split into a total of 192 sub-components. An additional 25 unmatched sources are included as new radio detections. The catalogue sources have a median spectral index of -0.85. Spectral flattening is seen towards lower frequencies with a median of -0.71 predicted at 182 MHz. The astrometric error is 7 arcsec compared to a 2.3 arcmin beam FWHM. The resulting catalogue covers ˜1400 deg2 and is complete to approximately 80 mJy within half beam power. This provides the most reliable discrete source sky model available to date in the MWA EoR0 field for precision foreground subtraction.

  19. An Eocene/Oligocene boundary geochemical proxy record from Ocean Drilling Program Site 1211 on the Shatsky Rise, Pacific Ocean.

    Science.gov (United States)

    Broadbent, T.; Clarke, L. J.; Leng, M.

    2009-04-01

    Evidence for significant global oceanographic and climatic change at the Eocene/Oligocene Boundary (EOB) is well documented, but records from the Pacific Ocean are limited to a single location, Site 1218 (Lear et al., 2004; Coxall et al., 2005). Here we present new data from the Shatsky Rise for cores collected during Ocean Drilling Program (ODP) Leg 198 that detail geochemical change across the boundary. During ODP Leg 198 an EOB section was recovered at Site 1211 (palaeodepth 2000-3000 m) on the southern high of the Shatsky Rise. This EOB section is a seemingly complete calcareous nannofossil ooze rich section, suggesting deposition above the carbonate compensation depth (CCD) throughout the EOB period. Deposition above the CCD should mean that changes in carbonate ion concentration, a potential control on foraminiferal Mg/Ca ratios, will be reduced in comparison to existing records from ODP Site 1218 (palaeodepth ~3800 m; Lear et al., 2004). Based on data published in the ODP Leg 198 Initial and Scientific Reports, relevant Site 1211 cores were sampled across the EOB, as marked out by the last occurrence of Hantkenina spp. and a notable colour reflectance change. In the absence of a palaeomagnetic record, Sr-isotope chronostratigraphy has been used to supplement the existing biostratigraphy and facilitate the development of a more robust age model. Samples were picked for both benthonic and planktonic foraminifera, which subsequently were analysed for stable carbon- and oxygen-isotope and element/Ca (particularly Mg/Ca) ratios. These foraminiferal proxy data are supplemented by stable-isotope records from the <38 micron fine fraction, %CaCO3 and scanning X-ray florescence (Ca and Fe) data from across the EOB. The geochemical proxy data show the ubiquitous EOB positive shift in oxygen-isotope ratios synchronous with increases in %CaCO3, colour reflectance and % sand, suggesting enhanced carbonate preservation/sedimentation compared to the late Eocene. Benthonic

  20. Issues in accelerometer methodology: the role of epoch length on estimates of physical activity and relationships with health outcomes in overweight, post-menopausal women

    Directory of Open Access Journals (Sweden)

    Underwood Darcy A

    2010-06-01

    Full Text Available Abstract Background Current accelerometer technology allows for data collection using brief time sampling intervals (i.e., epochs. The study aims were to examine the role of epoch length on physical activity estimates and subsequent relationships with clinically-meaningful health outcomes in post-menopausal women. Methods Data was obtained from the Woman On the Move through Activity and Nutrition Study (n = 102. Differences in activity estimates presented as 60s and 10s epochs were evaluated using paired t-tests. Relationships with health outcomes were examined using correlational and regression analyses to evaluate differences by epoch length. Results Inactivity, moderate- and vigorous-intensity activity (MVPA were significantly higher and light-intensity activity was significantly lower (all P P P Conclusion These findings suggest that although the use of a shorter time sampling interval may suggestively reduce misclassification error of physical activity estimates, associations with health outcomes did not yield strikingly different results. Additional studies are needed to further our understanding of the ways in which epoch length contributes to the ascertainment of physical activity in research studies. Trial Registration Clinical Trials Identifier: NCT00023543

  1. All-sky Multi-colour, Multi-epoch SuperCOSMOS Sky Survey Images Now Available in the VO Through SIAP

    Science.gov (United States)

    Hambly, N. C.; Read, M. A.; Holliman, M. S.; Cross, N. J. G.; Collins, R. S.; Mann, R. G.

    2009-09-01

    This paper describes a new all-sky Simple Image Access (SIA) protocol cut-out service based on the legacy Schmidt telescope photographic surveys (epoch 1949-2000) as digitised by the now decommissioned precision plate scanning facility SuperCOSMOS. Every part of the sky is covered in BRI (typical depths B=22, R=20, I=18 with 2 arcsec resolution) with at least two epochs in R; multiple-epoch images are available in the substantial survey overlap regions. Furthermore, specialist regions have additional filter/epoch coverage, e.g. Hα and matched R exposures in the Galactic Plane, and ˜200 multi-epoch/colour images spread over ˜30 years in the ESO/SRC survey field~287 at 21^h28^m, -45° (B1950). The service has been published to the international Virtual Observatory through the WFAU publishing registry, which can be found through the IVOA Registry of Registries. URL, http://www-wfau.roe.ac.uk:8080/ssa/SSS_SIAP IVORN, ivo://wfau.roe.ac.uk/sss-siap

  2. The Eocene-Oligocene transition at ODP Site 1263, Atlantic Ocean: decreases in nannoplankton size and abundance and correlation with benthic foraminiferal assemblages

    Science.gov (United States)

    Bordiga, M.; Henderiks, J.; Tori, F.; Monechi, S.; Fenero, R.; Thomas, E.

    2015-05-01

    The biotic response of calcareous nannoplankton to environmental and climatic changes during the Eocene-Oligocene transition (~34.8-32.7 Ma) was investigated at high resolution at Ocean Drilling Program (ODP) Site 1263 (Walvis Ridge, South East Atlantic Ocean), and compared with a lower resolution benthic foraminiferal record. During this time interval, the global climate which had been warm during the Eocene, under high levels of atmospheric CO2 (pCO2), transitioned into the cooler climate of the Oligocene, with overall lower pCO2. At Site 1263, the absolute nannofossil abundance (coccoliths per gram of sediment; N g-1) and the mean coccolith size decreased distinctly across the E-O boundary (EOB; 33.89 Ma), mainly due to a sharp decline in abundance of large-sized Reticulofenestra and Dictyococcites, within ~53 kyr. Since carbonate dissolution did not vary much across the EOB, the decrease in abundance and size of nannofossils may highlight an overall decrease in their export production, which could have led to an increased ratio of organic to inorganic carbon (calcite) burial, as well as variations in the food availability for benthic foraminifers. The benthic foraminiferal assemblage data show the global decline in abundance of rectilinear species with complex apertures in the latest Eocene (~34.5 Ma), potentially reflecting changes in the food source, thus phytoplankton, followed by transient increased abundance of species indicative of seasonal delivery of food to the sea floor (Epistominella spp.; ~34.04-33.54 Ma), with a short peak in overall food delivery at the EOB (buliminid taxa; ~33.9 Ma). After Oi-1 (starting at ~33.4 Ma), a high abundance of Nuttallides umbonifera indicates the presence of more corrosive bottom waters, possibly combined with less food arriving at the sea floor. The most important signals in the planktonic and benthic communities, i.e. the marked decrease of large reticulofenestrids, extinctions of planktonic foraminifer species and

  3. K-Ar age and geochemistry of the SW Japan Paleogene cauldron cluster: Implications for Eocene-Oligocene thermo-tectonic reactivation

    Science.gov (United States)

    Imaoka, T.; Kiminami, K.; Nishida, K.; Takemoto, M.; Ikawa, T.; Itaya, T.; Kagami, H.; Iizumi, S.

    2011-01-01

    Systematic K-Ar dating and geochemical analyses of Paleogene cauldrons in the Sanin Belt of SW Japan have been made to explore the relationship between the timing of their formation and the Paleogene subduction history of SW Japan documented in the Shimanto accretionary complex. We also examine the magma sources and tectonics beneath the backarc region of SW Japan at the eastern plate boundary of Eurasia. Fifty-eight new K-Ar ages and 19 previously reported radiometric age data show that the cauldrons formed during Middle Eocene to Early Oligocene time (43-30 Ma), following a period of magmatic hiatus from 52 to 43 Ma. The hiatus coincides with absence of an accretionary prism in the Shimanto Belt. Resumption of the magmatism that formed the cauldron cluster in the backarc was concurrent with voluminous influx of terrigenous detritus to the trench, as a common tectono-thermal event within a subduction system. The cauldrons are composed of medium-K calc-alkaline basalts to rhyolites and their plutonic equivalents. These rocks are characterized by lower concentrations of large ion lithophile elements (LILE) including K 2O, Ba, Rb, Th, U and Li, lower (La/Yb) n ratios, lower initial Sr isotopic ratios (0.7037-0.7052) and higher ɛNd( T) values (-0.5 to +3.5) relative to Late Cretaceous to Early Paleogene equivalents. There are clear trends from enriched to depleted signatures with decreasing age, from the Late Cretaceous to the Paleogene. The same isotopic shift is also confirmed in lower crust-derived xenoliths, and is interpreted as mobilization of pre-existing enriched lithospheric mantle by upwelling depleted asthenosphere. Relatively elevated geothermal gradients are presumed to have prevailed over wide areas of the backarc and forearc of the SW Japan arc-trench system during the Eocene to Oligocene. Newly identified Late Eocene low silica adakites and high-Mg andesites in the Sanin Belt and Early Eocene A-type granites in the SW Korea Peninsula probably formed

  4. Estudio sistemático y bioestratigráfico de los Eomyidae (Rodentia) del Oligoceno superior y Mioceno inferior español = Taxonomy and biostratigraphy of Eomyidae (Rodentia) from the upper Oligocene and lower Miocene of Spain

    NARCIS (Netherlands)

    Alvarez Sierra, M.A.

    1987-01-01

    This paper is the first fundamental study on Spanish Eomyidae. The flourishing time of this family in Europe was the Late Oligocene and Early Miocene. Four genera are recognized in this time span: Rhodanomys Depéret & Douxami, 1902, Ritteneria Stehlin & Schaub, 1951, Pseudotheridomys Schlosser, 1926

  5. Beamforming Errors in Murchison Widefield Array Phased Array Antennas and their effects on Epoch of Reionization Science

    CERN Document Server

    Neben, A R; Bradley, R F; Dillon, J S; Bernardi, G; Bowman, J D; Briggs, F; Cappallo, R J; Corey, B E; Deshpande, A A; Goeke, R; Greenhill, L J; Hazelton, B J; Johnston-Hollitt, M; Kaplan, D L; Lonsdale, C J; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Oberoi, D; Ord, S M; Prabu, T; Shankar, N Udaya; Srivani, K S; Subrahmanyan, R; Tingay, S J; Wayth, R B; Webster, R L; Williams, A; Williams, C L

    2016-01-01

    Accurate antenna beam models are critical for radio observations aiming to isolate the redshifted 21cm spectral line emission from the Dark Ages and the Epoch of Reionization and unlock the scientific potential of 21cm cosmology. Past work has focused on characterizing mean antenna beam models using either satellite signals or astronomical sources as calibrators, but antenna-to-antenna variation due to imperfect instrumentation has remained unexplored. We characterize this variation for the Murchison Widefield Array (MWA) through laboratory measurements and simulations, finding typical deviations of order +/- 10-20% near the edges of the main lobe and in the sidelobes. We consider the ramifications of these results for image- and power spectrum-based science. In particular, we simulate visibilities measured by a 100m baseline and find that using an otherwise perfect foreground model, unmodeled beamforming errors severely limit foreground subtraction accuracy within the region of Fourier space contaminated by ...

  6. SARAS: a precision system for measurement of the Cosmic Radio Background and signatures from the Epoch of Reionization

    CERN Document Server

    Patra, Nipanjana; Raghunathan, A; Shankar, N Udaya

    2012-01-01

    SARAS is a correlation spectrometer purpose designed for precision measurements of the cosmic radio background and faint features in the sky spectrum at long wavelengths that arise from redshifted 21-cm from gas in the reionization epoch. SARAS operates in the octave band 87.5-175 MHz. We present herein the system design arguing for a complex correlation spectrometer concept. The SARAS design concept provides a differential measurement between the antenna temperature and that of an internal reference termination, with measurements in switched system states allowing for cancellation of additive contaminants from a large part of the signal flow path including the digital spectrometer. A switched noise injection scheme provides absolute spectral calibration. Additionally, we argue for an electrically small frequency-independent antenna over an absorber ground. Various critical design features that aid in avoidance of systematics and in providing calibration products for the parametrization of other unavoidable s...

  7. Calibration Requirements for Detecting the 21 cm Epoch of Reionization Power Spectrum and Implications for the SKA

    CERN Document Server

    Barry, N; Sullivan, I; Morales, M F; Pober, J C

    2016-01-01

    21 cm Epoch of Reionization observations promise to transform our understanding of galaxy formation, but these observations are impossible without unprecedented levels of instrument calibration. We present end-to-end simulations of a full EoR power spectrum analysis including all of the major components of a real data processing pipeline: models of astrophysical foregrounds and EoR signal, frequency-dependent instrument effects, sky-based antenna calibration, and the full PS analysis. This study reveals that traditional sky-based per-frequency antenna calibration can only be implemented in EoR measurement analyses if the calibration model is unrealistically accurate. For reasonable levels of catalog completeness, the calibration introduces contamination in otherwise foreground-free power spectrum modes, precluding a PS measurement. We explore the origin of this contamination and potential mitigation techniques. We show that there is a strong joint constraint on the precision of the calibration catalog and the...

  8. Contribution of Cross-Correlations to the 21cm Angular Power Spectrum in the Epoch of Reionization

    CERN Document Server

    Zheng, Qian

    2009-01-01

    Measurement of the 21cm hyperfine transition of neutral hydrogen provides a unique probe of the epoch of reionization and the Dark Ages. Three major mechanisms are believed to dominate the radiation process: emission from neutral hydrogen surrounding the ionized bubbles of first galaxies and/or quasars, emission from neutral hydrogen inside minihalos, and absorption of diffuse neutral hydrogen against the cosmic microwave background. In the present work, by simply combining the existing analytic models for the three mechanisms, we investigate the contribution of cross-correlation between these three components to the total 21cm angular power spectrum, in the sense that neutral hydrogen associated with different radiation processes traces the large-scale structures of underlying density perturbations. While the overall 21cm power spectrum remains almost unchanged with the inclusion of the cross-correlations, the cross-correlation may play a key role in the determination of the 21cm power spectrum during the tr...

  9. Calibration of the EDGES Receiver to Observe the Global 21-cm Signature from the Epoch of Reionization

    CERN Document Server

    Monsalve, Raul A; Bowman, Judd D; Mozdzen, Thomas J

    2016-01-01

    The EDGES experiment strives to detect the the sky-average brightness temperature from the $21$-cm line emitted during the Epoch of Reionization (EoR) in the redshift range $14 \\gtrsim z \\gtrsim 6$. To probe this signal, EDGES conducts single-antenna measurements in the frequency range $\\sim 100-200$ MHz from the Murchison Radio-astronomy Observatory in Western Australia. In this paper we describe the current strategy for calibration of the EDGES instrument and, in particular, of its receiver. The calibration involves measuring accurately modeled passive and active noise sources connected to the receiver input in place of the antenna. We model relevant uncertainties that arise during receiver calibration and propagate them to the calibrated antenna temperature using a Monte Carlo approach. Calibration effects are isolated by assuming that the sky foregrounds and the antenna beam are perfectly known. We find that if five polynomial terms are used to account for calibration systematics, most of the calibration ...

  10. Parametrising Epoch of Reionization foregrounds: A deep survey of low-frequency point-source spectra with the MWA

    CERN Document Server

    Offringa, A R; Hurley-Walker, N; Johnston-Hollitt, M; McKinley, B; Barry, N; Beardsley, A P; Bowman, J D; Briggs, F; Carroll, P; Dillon, J S; Ewall-Wice, A; Feng, L; Gaensler, B M; Greenhill, L J; Hazelton, B J; Hewitt, J N; Jacobs, D C; Kim, H -S; Kittiwisit, P; Lenc, E; Line, J; Loeb, A; Mitchell, D A; Morales, M F; Neben, A R; Paul, S; Pindor, B; Pober, J C; Procopio, P; Riding, J; Sethi, S K; Shankar, N U; Subrahmanyan, R; Sullivan, I S; Tegmark, M; Thyagarajan, N; Tingay, S J; Wayth, R B; Webster, R L; Wyithe, J S B

    2016-01-01

    Experiments that pursue detection of signals from the Epoch of Reionization (EoR) are relying on spectral smoothness of source spectra at low frequencies. This article empirically explores the effect of foreground spectra on EoR experiments by measuring high-resolution full-polarization spectra for the 586 brightest unresolved sources in one of the MWA EoR fields using 45 h of observation. A novel peeling scheme is used to subtract 2500 sources from the visibilities with ionospheric and beam corrections, resulting in the deepest, confusion-limited MWA image so far. The resulting spectra are found to be affected by instrumental effects, which limit the constraints that can be set on source-intrinsic spectral structure. The sensitivity and power-spectrum of the spectra are analysed, and it is found that the spectra of residuals are dominated by PSF sidelobes from nearby undeconvolved sources. We release a catalogue describing the spectral parameters for each measured source.

  11. Morphology and distribution of Oligocene and Miocene pockmarks in the Danish North Sea -implications for bottom current activity and fluid migration

    DEFF Research Database (Denmark)

    Andresen, Katrine Juul; Huuse, Mads; Clausen, O.R.

    2008-01-01

    This study gives the first description of 33 mid-Oligocene and 646 late Miocene pockmarks mapped in the Danish part of the central North Sea. The pockmarks are all highly elongated, with average long- and short axes of 2.5 km and 700 m, and average internal depth of 30 m. The Miocene pockmarks...... development, only influenced by fluid expulsion and subsequent erosion by bottom currents. Group B pockmarks are influenced by bottom current erosion, current and gas winnowing and possibly authigenic carbonate precipitation. Group C pockmarks represent a further development from Group B pockmarks...... with further winnowing, carbonate precipitation and removal of seafloor sediment to form the ring-shape. Current erosion has exerted the major influence on the final geometry of 83% of the pockmarks. The pockmarks occur above gas-mature Jurassic source rocks, modelled to be in the generative window during...

  12. Lower Oligocene non-geniculate coralline red algal (Corallinales, Rhodophyta assemblage from Poljšica pri Podnartu (Upper Carniola, Slovenia

    Directory of Open Access Journals (Sweden)

    Luka Gale

    2008-12-01

    Full Text Available The Lower Oligocene Gornji Grad beds from Polj{ica pri Podnartu consist of marly limestone, mudstone, several layers of limestones and two layers of sandstones, and were deposited on a mixed carbonate-siliciclastic ramp.Especially the limestones contain rich fossil fauna and non-geniculate coralline red algae. These were systematicallycollected from four horizons and researched in thin sections under an optical microscope. Genera Lithoporella,Neogoniolithon, Spongites, Lithothamnion, Mesophyllum and Spongites were recognized. Surface area for each genus was calculated and the differences in the coralline assemblages in the four horizons were analysed. Thecorallines originate from two source areas: sandy-muddy bottom of a shallow marine environment, and small coral bioherms with its encrusters.

  13. The near-Top Oligocene unconformity in the Norwegian-Danish Basin: revisiting a major sequence boundary associated with fluid migration

    Science.gov (United States)

    Andresen, Katrine Juul; Rønø Clausen, Ole; Vind Hansen, Jens Peter; Huuse, Mads

    2015-04-01

    The near-Top Oligocene (NTO) unconformity is a well-known late Oligocene (Chattian) major sequence boundary associated with significant erosional truncations basinward of the clinoform breakpoint in the easternmost part of the North Sea. The surface features a number of discrete structures such as slides, localized incisions, and channels. Contourites are furthermore observed onlapping the NTO immediately basinward of the clinoform breakpoint, indicating a strong influence from contour parallel current systems. The previous observations are, however, disjointed due to the localised nature of 3D seismic data available. Having access to multiple high-quality 3D seismic surveys in an area covering approximately 3000 km2 and information from a number of wells from the Danish part of the Norwegian-Danish Basin enables us to present new detailed observations of features related to the NTO in a larger area, and to analyse the geological significance of the features and their mutual relations in a well-constrained regional context. The appearance of pockmarks caused by fluid venting at the late Oligocene seafloor vary across the area, and landward of the NTO clinoform breakpoint the pockmarks are generally small and circular (c. 50 m in diameter) clustered in discrete pockmark fields and pockmark strings. Basinward of the clinoform breakpoint the pockmarks are large ellipsoidal (NW-SE striking) depressions (400-2500 m long and 100-150 m wide) elongated due to current scour by the prevailing contour current system as also reported for Miocene pockmarks from the Danish Central Graben area. Previous studies suggest that the NTO probably formed during a longer period of submarine non-deposition and therefore may be associated with a hiatus of several million years in the study area. The abundant pockmarks show that this period furthermore was characterised by significant fluid venting. Sub-circular features observed approximately at the clinoform breakpoint are mainly

  14. Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays

    Science.gov (United States)

    Masías-Meza, J. J.; Dasso, S.; Démoulin, P.; Rodriguez, L.; Janvier, M.

    2016-08-01

    Context. Interplanetary coronal mass ejections (ICMEs) are the interplanetary manifestations of solar eruptions. The overtaken solar wind forms a sheath of compressed plasma at the front of ICMEs. Magnetic clouds (MCs) are a subset of ICMEs with specific properties (e.g. the presence of a flux rope). When ICMEs pass near Earth, ground observations indicate that the flux of Galactic cosmic rays (GCRs) decreases. Aims: The main aims of this paper are to find common plasma and magnetic properties of different ICME sub-structures and which ICME properties affect the flux of GCRs near Earth. Methods: We used a superposed epoch method applied to a large set of ICMEs observed in situ by the spacecraft ACE, between 1998 and 2006. We also applied a superposed epoch analysis on GCRs time series observed with the McMurdo neutron monitors. Results: We find that slow MCs at 1 AU have on average more massive sheaths. We conclude that this is because they are more effectively slowed down by drag during their travel from the Sun. Slow MCs also have a more symmetric magnetic field and sheaths expanding similarly as their following MC, while in contrast, fast MCs have an asymmetric magnetic profile and a sheath in compression. In all types of MCs, we find that the proton density and the temperature and the magnetic fluctuations can diffuse within the front of the MC due to 3D reconnection. Finally, we derive a quantitative model that describes the decrease in cosmic rays as a function of the amount of magnetic fluctuations and field strength. Conclusions: The obtained typical profiles of sheath, MC and GCR properties corresponding to slow, middle, and fast ICMEs, can be used for forecasting or modelling these events, and to better understand the transport of energetic particles in ICMEs. They are also useful for improving future operative space weather activities.

  15. What next-generation 21 cm power spectrum measurements can teach us about the epoch of reionization

    Energy Technology Data Exchange (ETDEWEB)

    Pober, Jonathan C.; Morales, Miguel F. [Physics Department, University of Washington, Seattle, WA 98105 (United States); Liu, Adrian; McQuinn, Matthew; Parsons, Aaron R. [Department of Astronomy, University of California Berkeley, Berkeley, CA 94720 (United States); Dillon, Joshua S.; Hewitt, Jacqueline N.; Tegmark, Max [Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Aguirre, James E. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Bowman, Judd D.; Jacobs, Daniel C. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85004 (United States); Bradley, Richard F. [Astronomy Department, University of Virginia, Charlottesville, VA 22904 (United States); Carilli, Chris L. [National Radio Astronomy Observatory, Socorro, NM 87801 (United States); DeBoer, David R. [Radio Astronomy Laboratory, University of California Berkeley, Berkeley, CA 94720 (United States); Werthimer, Dan J. [Space Sciences Laboratory, University of California Berkeley, Berkeley, CA 94720 (United States)

    2014-02-20

    A number of experiments are currently working toward a measurement of the 21 cm signal from the epoch of reionization (EoR). Whether or not these experiments deliver a detection of cosmological emission, their limited sensitivity will prevent them from providing detailed information about the astrophysics of reionization. In this work, we consider what types of measurements will be enabled by the next generation of larger 21 cm EoR telescopes. To calculate the type of constraints that will be possible with such arrays, we use simple models for the instrument, foreground emission, and the reionization history. We focus primarily on an instrument modeled after the ∼0.1 km{sup 2} collecting area Hydrogen Epoch of Reionization Array concept design and parameterize the uncertainties with regard to foreground emission by considering different limits to the recently described 'wedge' footprint in k space. Uncertainties in the reionization history are accounted for using a series of simulations that vary the ionizing efficiency and minimum virial temperature of the galaxies responsible for reionization, as well as the mean free path of ionizing photons through the intergalactic medium. Given various combinations of models, we consider the significance of the possible power spectrum detections, the ability to trace the power spectrum evolution versus redshift, the detectability of salient power spectrum features, and the achievable level of quantitative constraints on astrophysical parameters. Ultimately, we find that 0.1 km{sup 2} of collecting area is enough to ensure a very high significance (≳ 30σ) detection of the reionization power spectrum in even the most pessimistic scenarios. This sensitivity should allow for meaningful constraints on the reionization history and astrophysical parameters, especially if foreground subtraction techniques can be improved and successfully implemented.

  16. Environmental Profile of a Community's Health (EPOCH: an ecometric assessment of measures of the community environment based on individual perception.

    Directory of Open Access Journals (Sweden)

    Daniel J Corsi

    Full Text Available BACKGROUND: Public health research has turned towards examining upstream, community-level determinants of cardiovascular disease risk factors. Objective measures of the environment, such as those derived from direct observation, and perception-based measures by residents have both been associated with health behaviours. However, current methods are generally limited to objective measures, often derived from administrative data, and few instruments have been evaluated for use in rural areas or in low-income countries. We evaluate the reliability of a quantitative tool designed to capture perceptions of community tobacco, nutrition, and social environments obtained from interviews with residents in communities in 5 countries. METHODOLOGY/ PRINCIPAL FINDINGS: Thirteen measures of the community environment were developed from responses to questionnaire items from 2,360 individuals residing in 84 urban and rural communities in 5 countries (China, India, Brazil, Colombia, and Canada in the Environmental Profile of a Community's Health (EPOCH study. Reliability and other properties of the community-level measures were assessed using multilevel models. High reliability (>0.80 was demonstrated for all community-level measures at the mean number of survey respondents per community (n = 28 respondents. Questionnaire items included in each scale were found to represent a common latent factor at the community level in multilevel factor analysis models. CONCLUSIONS/ SIGNIFICANCE: Reliable measures which represent aspects of communities potentially related to cardiovascular disease (CVD/risk factors can be obtained using feasible sample sizes. The EPOCH instrument is suitable for use in different settings to explore upstream determinants of CVD/risk factors.

  17. A Testing Ground for Polarized Maser Transport: Multi-Epoch Analysis of a π/2 Electric Vector Rotation

    Science.gov (United States)

    Tobin, Taylor; Kemball, Athol J.

    2017-01-01

    The near circumstellar environment (NCSE) around Asymptotic Giant Branch (AGB) stars is chaotic, exhibiting shocks, turbulence, velocity gradients, and a potentially dynamically significant magnetic field (Vlemmings et al. 2005). Very Long Baseline Interferometry (VLBI) of masers emanating from these environments can provide sub-milliarcsecond angular resolution of the NCSE (Kemball 2002). Solidifying the origin of the polarization in these masers may be the key to understanding the magnitude and behavior of these stars' magnetic fields (eg. Goldreich et al. 1973; Elitzur 1996). However, other theories of polarized maser transport do not rely heavily on the magnetic field; some are more dependent on anisotropic pumping (Elitzur 1996; Watson 2009) or anisotropic resonant scattering (Asensio Ramos et al. 2005; Houde 2014). One optimal test of these theories is their ability to account for a π/2 rotation of the Electric Vector Position Angle (EVPA) observed in some maser features. The profile of linear polarization across such a feature varies with the generating mechanism. In this study, we utilize multi-epoch observations of ν=1, J=1-0 SiO maser emission around TX Cam (Diamond & Kemball 2003; Kemball et al. 2009; Gonidakis et al. 2010) to analyze a single feature with a π/2 rotation that persisted for five epochs and compare it to the behavior expected according to various theories of maser polarization. In addition, we analyze the low levels of circular polarization - now achievable due to recent improvements in millimeter-wavelength circular polarization reduction (Kemball & Richter 2011) - and compare their correlation with other parameters to further test these polarization generation theories.

  18. The Early Prevention of Obesity in CHildren (EPOCH Collaboration - an Individual Patient Data Prospective Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Simes John

    2010-11-01

    Full Text Available Abstract Background Efforts to prevent the development of overweight and obesity have increasingly focused early in the life course as we recognise that both metabolic and behavioural patterns are often established within the first few years of life. Randomised controlled trials (RCTs of interventions are even more powerful when, with forethought, they are synthesised into an individual patient data (IPD prospective meta-analysis (PMA. An IPD PMA is a unique research design where several trials are identified for inclusion in an analysis before any of the individual trial results become known and the data are provided for each randomised patient. This methodology minimises the publication and selection bias often associated with a retrospective meta-analysis by allowing hypotheses, analysis methods and selection criteria to be specified a priori. Methods/Design The Early Prevention of Obesity in CHildren (EPOCH Collaboration was formed in 2009. The main objective of the EPOCH Collaboration is to determine if early intervention for childhood obesity impacts on body mass index (BMI z scores at age 18-24 months. Additional research questions will focus on whether early intervention has an impact on children's dietary quality, TV viewing time, duration of breastfeeding and parenting styles. This protocol includes the hypotheses, inclusion criteria and outcome measures to be used in the IPD PMA. The sample size of the combined dataset at final outcome assessment (approximately 1800 infants will allow greater precision when exploring differences in the effect of early intervention with respect to pre-specified participant- and intervention-level characteristics. Discussion Finalisation of the data collection procedures and analysis plans will be complete by the end of 2010. Data collection and analysis will occur during 2011-2012 and results should be available by 2013. Trial registration number ACTRN12610000789066

  19. Effect of strain-weakening on Oligocene-Miocene self-organization of the Australian-Pacific plate boundary fault in southern New Zealand: Insights from numerical modelling

    Science.gov (United States)

    Feng, Xiaojun; Jessell, Mark Walter; Amponsah, Prince Ofori; Martin, Roland; Ganne, Jérôme; Liu, Daqing; Batt, Geoffrey E.

    2016-10-01

    Tectonic inheritance acquired from past geological events can control the formation of new plate boundaries. The aim of this paper is to explore the role of inherited NE and NW trending fabrics and their rheological influence on the propagation of Oligocene-Miocene strike-slip faulting that matured to become the Australian-Pacific plate boundary fault in southern New Zealand. Strain weakening plays a significant role in controlling the formation, growth and evolution of strain localization. In this study, three-dimensional thermo-mechanical models have been used to explore the effect of strain weakening on the Oligocene-Miocene self-organization of strain localization. Strain weakening is simulated through decreasing either the coefficient of friction of upper crust, its cohesion, or the rheological viscosity contrast between the inherited structures and their surrounding wall rocks. Viscosity contrast is obtained by varying the viscosity of inherited structures. Softening coefficient