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Sample records for clarion-clipperton abyssal plane

  1. Epithermal neutron activation analysis investigation of Clarion-Clipperton abyssal plane clay and polymetallic micronodules

    Energy Technology Data Exchange (ETDEWEB)

    Duliu, O.G. [University of Bucharest, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077125 Magurele, Ilfov (Romania)], E-mail: duliu@b.astral.ro; Cristache, C.I. [National Institute of Research and Development for Physics and Nuclear Engineering ' Horia-Hulubei' , P.O. Box MG-6, 077125 Magurele, Ilfov (Romania)], E-mail: ocarmen@ifin.nipne.ro; Culicovc, O.A. [Joint Institute of Nuclear Research, 6, Joliot Curie str., 141980 Dubna (Russian Federation)], E-mail: otilia_culicov@yahoo.com; Frontasyeva, M.V. [Joint Institute of Nuclear Research, 6, Joliot Curie str., 141980 Dubna (Russian Federation)], E-mail: marina@nf.jinr.ru; Szobotca, S.A. [National Institute of Geoecology and Marine Geology, 34 Dimitrie Onciul str., 024504 Bucharest (Romania)], E-mail: szobi@geoecomar.ro; Toma, M. [National Institute of Research and Development for Physics and Nuclear Engineering ' Horia-Hulubei' , P.O. Box MG-6, 077125 Magurele, Ilfov (Romania)

    2009-05-15

    The content of seven major (Na, Al, Cl, Mn, K, Ca, Ti, Fe) and 30 trace (Sc, V, Cr, Ni, Co, Zn, Cu, As, Sr, Rb, Zr, Mo, Sn, In, Sb, Ba, Cs, La, Ce, Nd, Eu, Sm, Tb, Dy, Yb, Hf, Ta, W, Th, U) elements determined by INAA in 13 samples of abyssal clay and two samples of micronodules collected from the North pacific Ocean Clarion-Clipperton abyssal plane is presented and discussed with respect to some rocks models.

  2. Epithermal neutron activation analysis investigation of Clarion-Clipperton abyssal plane clay and polymetallic micronodules.

    Science.gov (United States)

    Duliu, O G; Cristache, C I; Culicovc, O A; Frontasyeva, M V; Szobotca, S A; Toma, M

    2009-05-01

    The content of seven major (Na, Al, Cl, Mn, K, Ca, Ti, Fe) and 30 trace (Sc, V, Cr, Ni, Co, Zn, Cu, As, Sr, Rb, Zr, Mo, Sn, In, Sb, Ba, Cs, La, Ce, Nd, Eu, Sm, Tb, Dy, Yb, Hf, Ta, W, Th, U) elements determined by INAA in 13 samples of abyssal clay and two samples of micronodules collected from the North pacific Ocean Clarion-Clipperton abyssal plane is presented and discussed with respect to some rocks models. PMID:19230682

  3. Abyssal fauna of the UK-1 polymetallic nodule exploration claim, Clarion-Clipperton Zone, central Pacific Ocean: Echinodermata

    OpenAIRE

    Glover, Adrian G.; Wiklund,Helena; Rabone, Muriel; Amon, Diva J; Smith, Craig R.; O'Hara,Tim; Mah, Christopher L.; Dahlgren, Thomas G

    2016-01-01

    Abstract We present data from a DNA taxonomy register of the abyssal benthic Echinodermata collected as part of the Abyssal Baseline (ABYSSLINE) environmental survey cruise ‘AB01’ to the UK Seabed Resources Ltd (UKSRL) polymetallic-nodule exploration claim ‘UK-1’ in the eastern Clarion-Clipperton Zone (CCZ), central Pacific Ocean abyssal plain. Morphological and genetic data are presented for 17 species (4 Asteroidea , 4 Crinoidea , 2 Holothuroidea and 7 Ophiuroidea ) identified by a combinat...

  4. Abyssal fauna of the UK-1 polymetallic nodule exploration claim, Clarion-Clipperton Zone, central Pacific Ocean: Echinodermata.

    Science.gov (United States)

    Glover, Adrian G; Wiklund, Helena; Rabone, Muriel; Amon, Diva J; Smith, Craig R; O'Hara, Tim; Mah, Christopher L; Dahlgren, Thomas G

    2016-01-01

    We present data from a DNA taxonomy register of the abyssal benthic Echinodermata collected as part of the Abyssal Baseline (ABYSSLINE) environmental survey cruise 'AB01' to the UK Seabed Resources Ltd (UKSRL) polymetallic-nodule exploration claim 'UK-1' in the eastern Clarion-Clipperton Zone (CCZ), central Pacific Ocean abyssal plain. Morphological and genetic data are presented for 17 species (4 Asteroidea, 4 Crinoidea, 2 Holothuroidea and 7 Ophiuroidea) identified by a combination of morphological and genetic data. No taxa matched previously published genetic sequences, but 8 taxa could be assigned to previously-described species based on morphology, although here we have used a precautionary approach in taxon assignments to avoid over-estimating species ranges. The Clarion-Clipperton Zone is a region undergoing intense exploration for potential deep-sea mineral extraction. We present these data to facilitate future taxonomic and environmental impact study by making both data and voucher materials available through curated and accessible biological collections. PMID:26929713

  5. Insights into the abundance and diversity of abyssal megafauna in a polymetallic-nodule region in the eastern Clarion-Clipperton Zone

    Science.gov (United States)

    Amon, Diva J.; Ziegler, Amanda F.; Dahlgren, Thomas G.; Glover, Adrian G.; Goineau, Aurélie; Gooday, Andrew J.; Wiklund, Helena; Smith, Craig R.

    2016-01-01

    There is growing interest in mining polymetallic nodules in the abyssal Clarion-Clipperton Zone (CCZ) in the Pacific. Nonetheless, benthic communities in this region remain poorly known. The ABYSSLINE Project is conducting benthic biological baseline surveys for the UK Seabed Resources Ltd. exploration contract area (UK-1) in the CCZ. Using a Remotely Operated Vehicle, we surveyed megafauna at four sites within a 900 km2 stratum in the UK-1 contract area, and at a site ~250 km east of the UK-1 area, allowing us to make the first estimates of abundance and diversity. We distinguished 170 morphotypes within the UK-1 contract area but species-richness estimators suggest this could be as high as 229. Megafaunal abundance averaged 1.48 ind. m−2. Seven of 12 collected metazoan species were new to science, and four belonged to new genera. Approximately half of the morphotypes occurred only on polymetallic nodules. There were weak, but statistically significant, positive correlations between megafaunal and nodule abundance. Eastern-CCZ megafaunal diversity is high relative to two abyssal datasets from other regions, however comparisons with CCZ and DISCOL datasets are problematic given the lack of standardised methods and taxonomy. We postulate that CCZ megafaunal diversity is driven in part by habitat heterogeneity. PMID:27470484

  6. Insights into the abundance and diversity of abyssal megafauna in a polymetallic-nodule region in the eastern Clarion-Clipperton Zone

    Science.gov (United States)

    Amon, Diva J.; Ziegler, Amanda F.; Dahlgren, Thomas G.; Glover, Adrian G.; Goineau, Aurélie; Gooday, Andrew J.; Wiklund, Helena; Smith, Craig R.

    2016-07-01

    There is growing interest in mining polymetallic nodules in the abyssal Clarion-Clipperton Zone (CCZ) in the Pacific. Nonetheless, benthic communities in this region remain poorly known. The ABYSSLINE Project is conducting benthic biological baseline surveys for the UK Seabed Resources Ltd. exploration contract area (UK-1) in the CCZ. Using a Remotely Operated Vehicle, we surveyed megafauna at four sites within a 900 km2 stratum in the UK-1 contract area, and at a site ~250 km east of the UK-1 area, allowing us to make the first estimates of abundance and diversity. We distinguished 170 morphotypes within the UK-1 contract area but species-richness estimators suggest this could be as high as 229. Megafaunal abundance averaged 1.48 ind. m‑2. Seven of 12 collected metazoan species were new to science, and four belonged to new genera. Approximately half of the morphotypes occurred only on polymetallic nodules. There were weak, but statistically significant, positive correlations between megafaunal and nodule abundance. Eastern-CCZ megafaunal diversity is high relative to two abyssal datasets from other regions, however comparisons with CCZ and DISCOL datasets are problematic given the lack of standardised methods and taxonomy. We postulate that CCZ megafaunal diversity is driven in part by habitat heterogeneity.

  7. An End-to-End DNA Taxonomy Methodology for Benthic Biodiversity Survey in the Clarion-Clipperton Zone, Central Pacific Abyss

    Directory of Open Access Journals (Sweden)

    Adrian G. Glover

    2015-12-01

    Full Text Available Recent years have seen increased survey and sampling expeditions to the Clarion-Clipperton Zone (CCZ, central Pacific Ocean abyss, driven by commercial interests from contractors in the potential extraction of polymetallic nodules in the region. Part of the International Seabed Authority (ISA regulatory requirements are that these contractors undertake environmental research expeditions to their CCZ exploration claims following guidelines approved by the ISA Legal and Technical Commission (ISA, 2010. Section 9 (e of these guidelines instructs contractors to “…collect data on the sea floor communities specifically relating to megafauna, macrofauna, meiofauna, microfauna, nodule fauna and demersal scavengers”. There are a number of methodological challenges to this, including the water depth (4000–5000 m, extremely warm surface waters (~28 °C compared to bottom water (~1.5 °C and great distances to ports requiring a large and long seagoing expedition with only a limited number of scientists. Both scientists and regulators have recently realized that a major gap in our knowledge of the region is the fundamental taxonomy of the animals that live there; this is essential to inform our knowledge of the biogeography, natural history and ultimately our stewardship of the region. Recognising this, the ISA is currently sponsoring a series of taxonomic workshops on the CCZ fauna and to assist in this process we present here a series of methodological pipelines for DNA taxonomy (incorporating both molecular and morphological data of the macrofauna and megafauna from the CCZ benthic habitat in the recent ABYSSLINE cruise program to the UK-1 exploration claim. A major problem on recent CCZ cruises has been the collection of high-quality samples suitable for both morphology and DNA taxonomy, coupled with a workflow that ensures these data are made available. The DNA sequencing techniques themselves are relatively standard, once good samples have been

  8. Biodiversity of nematode assemblages from the region of the Clarion-Clipperton Fracture Zone, an area of commercial mining interest

    Directory of Open Access Journals (Sweden)

    Hawkins Lawrence E

    2003-01-01

    Full Text Available Abstract Background The possibility for commercial mining of deep-sea manganese nodules is currently under exploration in the abyssal Clarion-Clipperton Fracture Zone. Nematodes have potential for biomonitoring of the impact of commercial activity but the natural biodiversity is unknown. We investigate the feasibility of nematodes as biomonitoring organisms and give information about their natural biodiversity. Results The taxonomic composition (at family to genus level of the nematode fauna in the abyssal Pacific is similar, but not identical to, the North Atlantic. Given the immature state of marine nematode taxonomy, it is not possible to comment on the commonality or otherwise of species between oceans. The between basin differences do not appear to be directly linked to current ecological factors. The abyssal Pacific region (including the Fracture Zone could be divided into two biodiversity subregions that conform to variations in the linked factors of flux to the benthos and of sedimentary characteristics. Richer biodiversity is associated with areas of known phytodetritus input and higher organic-carbon flux. Despite high reported sample diversity, estimated regional diversity is less than 400 species. Conclusion The estimated regional diversity of the CCFZ is a tractable figure for biomonitoring of commercial activities in this region using marine nematodes, despite the immature taxonomy (i.e. most marine species have not been described of the group. However, nematode ecology is in dire need of further study.

  9. Threatened by mining, polymetallic nodules are required to preserve abyssal epifauna

    OpenAIRE

    Vanreusel, Ann; Hilario, Ana; Ribeiro, Pedro A.; Menot, Lenaick; Arbizu, Pedro Martínez

    2016-01-01

    Polymetallic nodule mining at abyssal depths in the Clarion Clipperton Fracture Zone (Eastern Central Pacific) will impact one of the most remote and least known environments on Earth. Since vast areas are being targeted by concession holders for future mining, large-scale effects of these activities are expected. Hence, insight into the fauna associated with nodules is crucial to support effective environmental management. In this study video surveys were used to compare the epifauna from si...

  10. Threatened by mining, polymetallic nodules are required to preserve abyssal epifauna

    Science.gov (United States)

    Vanreusel, Ann; Hilario, Ana; Ribeiro, Pedro A.; Menot, Lenaick; Arbizu, Pedro Martínez

    2016-06-01

    Polymetallic nodule mining at abyssal depths in the Clarion Clipperton Fracture Zone (Eastern Central Pacific) will impact one of the most remote and least known environments on Earth. Since vast areas are being targeted by concession holders for future mining, large-scale effects of these activities are expected. Hence, insight into the fauna associated with nodules is crucial to support effective environmental management. In this study video surveys were used to compare the epifauna from sites with contrasting nodule coverage in four license areas. Results showed that epifaunal densities are more than two times higher at dense nodule coverage (>25 versus ≤10 individuals per 100 m2), and that taxa such as alcyonacean and antipatharian corals are virtually absent from nodule-free areas. Furthermore, surveys conducted along tracks from trawling or experimental mining simulations up to 37 years old, suggest that the removal of epifauna is almost complete and that its full recovery is slow. By highlighting the importance of nodules for the epifaunal biodiversity of this abyssal area, we urge for cautious consideration of the criteria for determining future preservation zones.

  11. Abyssal sediment erosion from the Central Indian Basin: Evidence from radiochemical and radiolarian studies

    Digital Repository Service at National Institute of Oceanography (India)

    Banakar, V.K.; Gupta, S.M.; Padmavati, V.K.

    -16. Levitus, S., 1982. Climatological Atlas of the World Oceans. Natl. Oceanic Atmos. Admin. Prof. Pap., 13: 172 pp. Mangini, A. and Kuhnel, U., 1987. Depositional history in the Clarion-Clipperton zone during the last 250,000 years - 23°Th and 23tpa...

  12. Feasibility study on manganese nodules recovery in the Clarion-Clipperton Zone

    OpenAIRE

    Agarwal, Baivau; Hu, Pan; Placidi, Marco; Santo, Harrif; Zhou, Jenny Jin

    2012-01-01

    The sea occupies three quarters of the area on the earth and provides various kinds of resources to mankind in the form of minerals, food, medicines and even energy. “Seabed exploitation” specifically deals with recovery of the resources that are found on the seabed, in the form of solids, liquids and gasses (methane hydrates, oil and natural gas). The resources are abundant; nevertheless the recovery process from the seabed, poses various challenges to mankind. This study starts with a revie...

  13. Bidecadal Thermal Changes in the Abyssal Ocean

    OpenAIRE

    Wunsch, Carl; Heimbach, Patrick

    2014-01-01

    A dynamically consistent state estimate is used for the period 1992–2011 to describe the changes in oceanic temperatures and heat content, with an emphasis on determining the noise background in the abyssal (below 2000 m) depths. Interpretation requires close attention to the long memory of the deep ocean, implying that meteorological forcing of decades to thousands of years ago should still be producing trendlike changes in abyssal heat content. Much of the deep-ocean volume remained unobser...

  14. Changes in abundance and community structure of nematodes from the abyssal polymetallic nodule field, Tropical Northeast Pacific

    Science.gov (United States)

    Miljutin, Dmitry; Miljutina, Maria; Messié, Monique

    2015-12-01

    Deep-sea fields of polymetallic nodules in the Clarion-Clipperton Zone (CCFZ, tropical NE Pacific) are currently being investigated to assess their potential for commercial mining. During such mining, benthic communities will be inevitably disturbed or destroyed. Therefore, assessments of their standing stock and composition may be helpful for the future evaluation of possible impacts of commercial nodule exploitation. Analysis of nematode communities (at genus level) inhabiting the French license area of the CCFZ were studied based on data from the cruises NODINAUT (2004) and BIONOD (2012). The total nematode density was ca. 1.5-fold higher in 2012 as compared with 2004. This reflected a 2-2.5 times higher density of non-selective deposit-feeders (i.e. possessing a small buccal cavity without armature) in 2012 compared with 2004, whereas no significant differences between sampling periods were observed in the density of the other feeding groups. Consequently, whilst the list of the most abundant genera was identical, their relative abundances changed significantly. The relative abundance of the genus Thalassomonhystera was two times greater in 2012 than in 2004, whereas the relative abundances of the genera Acantholaimus and Theristus were significantly lower in 2012 (10% and 4%, respectively) than in 2004 (28% and 9%). Nematode diversity (including values of diversity indices and total number of recorded genera) was significantly lower in 2012 in comparison with 2004. Although our data do not take into account seasonal and shorter temporal scales of variability in nematode assemblages, we report here that a certain fraction of variations observed between the two sampling periods could be associated with differences in primary production. Future studies should aim to better characterise temporal variability in nematode communities of the CCFZ at seasonal and interannual scales.

  15. Geology and geochemistry of abyssal plains

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, P.P.E.; Thomson, J. (eds.)

    1987-01-01

    In this publication is assembled a set of 14 papers from the presentations at a meeting of the Marine Studies Group of the Geological Society, held on the 29th and 30th January 1986. The papers cover various aspects of the geophysics, sedimentology, geochemistry and geotechnics of abyssal-plain sediments. During the late 1970s an international research program began to examine selected areas of the N Atlantic and Pacific Ocean sea beds to assess the feasibility of disposal of radioactive wastes in deep-sea sediments. The considerations of sea-floor properties required for such studies had the results that some of the N Atlantic study areas were in abyssal plains. The availability of new geological information from this program provided the impetus for convening this meeting, but the papers are not restricted to those deriving from such studies. All papers have been abstracted separately for inclusion on the Energy Data Base.

  16. Global variations in abyssal peridotite compositions

    Science.gov (United States)

    Warren, Jessica M.

    2016-04-01

    Abyssal peridotites are ultramafic rocks collected from mid-ocean ridges that are the residues of adiabatic decompression melting. Their compositions provide information on the degree of melting and melt-rock interaction involved in the formation of oceanic lithosphere, as well as providing constraints on pre-existing mantle heterogeneities. This review presents a compilation of abyssal peridotite geochemical data (modes, mineral major elements, and clinopyroxene trace elements) for > 1200 samples from 53 localities on 6 major ridge systems. On the basis of composition and petrography, peridotites are classified into one of five lithological groups: (1) residual peridotite, (2) dunite, (3) gabbro-veined and/or plagioclase-bearing peridotite, (4) pyroxenite-veined peridotite, and (5) other types of melt-added peridotite. Almost a third of abyssal peridotites are veined, indicating that the oceanic lithospheric mantle is more fertile, on average, than estimates based on residual peridotites alone imply. All veins appear to have formed recently during melt transport beneath the ridge, though some pyroxenites may be derived from melting of recycled oceanic crust. A limited number of samples are available at intermediate and fast spreading rates, with samples from the East Pacific Rise indicating high degrees of melting. At slow and ultra-slow spreading rates, residual abyssal peridotites define a large (0-15% modal clinopyroxene and spinel Cr# = 0.1-0.6) compositional range. These variations do not match the prediction for how degree of melting should vary as a function of spreading rate. Instead, the compositional ranges of residual peridotites are derived from a combination of melting, melt-rock interaction and pre-existing compositional variability, where melt-rock interaction is used here as a general term to refer to the wide range of processes that can occur during melt transport in the mantle. Globally, ~ 10% of abyssal peridotites are refractory (0

  17. A STUDY ON THE BAROCLINIC STRUCTURE OF THE ABYSSAL CIRCULATION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, the linear continuously stratified model of the abyssal circulation proposed by Pedlosky (1992) was extended to include the second order term -(γθzzz) in the vertical turbulent mixing parameterization of -(w′θ′)z=kυθzz-γθzzz, in which kυ is a vertical diffusion coefficient, and γ is the second order coefficient of turbulent mixing (or simply called γ-term and γ<0 is only allowed). The influence of the γ-term on the baroclinic structure of the abyssal circulation driven by upwelling out of the abyss was investigated. It was found that the γ-term has a noticeable influence on the baroclinic structure of the upwelling driven abyssal circulation. For uniform upwelling, it favors the baroclinic layering of the abyssal circulation in the eastern part of the basin, but prevents the layering in the west. In addition, this parameter was found to decrease the vertically averaging meridional velocity of the abyssal circulation from the west to the east on the southern boundary. For upwelling localized near the eastern boundary, the γ-term favors baroclinic layering of the abyssal circulation in the whole basin. Especially, on the southern boundary the γ-term could strengthen the vertically averaging meridional velocity in the west, but greatly weaken it in the east. The model presented here might be considered as an extension of the Pedlosky baroclinic model of the abyssal circulation.

  18. A study on the baroclinic structure of the abyssal circulation

    Science.gov (United States)

    Luo, De-Hai; Huang, Fei

    2001-03-01

    In this paper, the linear continuously tratified model of the abyssal circulation proposed by Pedlosky (1992) was extended to include the second order term -(γθ zzz ) in the vertical turbulent mixing parameterization of - overline {(w' θ ' )} _z = k_u θ _{zz} - γ θ _{zzz} , in which k v is a vertical diffusion coefficient, and γ is the second order coefficient of turbulent mixing (or simply called γ-term and γ<0 is only allowed). The influence of the γ-term on the baroclinic structure of the abyssal circulation driven by upwelling out of the abyss was investigated. It was found that the γ-term has a noticeable influence on the baroclinic structure of the upwelling driven abyssal circulation. For uniform upwelling, it favors the baroclinic layering of the abyssal circulation in the eastern part of the basin, but prevents the layering in the west. In addition, this parameter was found to decrease the vertically averaging meridional velocity of the abyssal circulation from the west to the east on the southern boundary. For upwelling localized near the eastern boundary, the γ-term favors baroclinic layering of the abyssal circulation in the whole basin. Especially, on the southern boundary the γ-term could strengthen the vertically averaging meridional velocity in the west, but greatly weaken it in the east. The model presented here might be considered as an extension of the Pedlosky baroclinic model of the abyssal circulation.

  19. Pacific deep circulation: A velocity increase at the end of the interglacial stage 5?

    Science.gov (United States)

    Mangini, A.; Dominik, J.; Müller, P. J.; Stoffers, P.

    1982-12-01

    Re-evaluation of 230Th and 231Pa data on 16 sediment cores recovered in the equatorial North Pacific, between the Clarion-Clipperton Fracture Zone and in the Aitutaki Passage, suggests that a major event modifying the sedimentary regime occurred about 70,000 y B.P. The change is recorded in 12 cores either as the onset of sediment accumulation following a period of sediment erosion or as a remarkable increase in the accumulation rate resulting from enhanced accumulation of redistributed sediment in abyssal plains. Both the onset of sediment accumulation and the enhanced accumulation of redistributed sediment could be attributed to bottom water velocities similar to present ones. Erosion, by contrast, is related to a period of maximum bottom water flow at the boundary of interglacial stage 5 and glacial stage 4.

  20. Biogeochemical, Isotopic and Bacterial Distributions Trace Oceanic Abyssal Circulation.

    Science.gov (United States)

    Rubino, Angelo; Bensi, Manuel; Hainbucher, Dagmar; Zanchettin, Davide; Mapelli, Francesca; Ogrinc, Nives; Marchetto, Davide; Borin, Sara; Cardin, Vanessa; Fajon, Vesna; Horvat, Milena; Taricco, Carla; Baldi, Franco

    2016-01-01

    We explore the possibility of tracing routes of dense waters toward and within the ocean abyss by the use of an extended set of observed physical and biochemical parameters. To this purpose, we employ mercury, isotopic oxygen, biopolymeric carbon and its constituents, together with indicators of microbial activity and bacterial diversity found in bottom waters of the Eastern Mediterranean. In this basin, which has been considered as a miniature global ocean, two competing sources of bottom water (one in the Adriatic and one in the Aegean seas) contribute to the ventilation of the local abyss. However, due to a recent substantial reduction of the differences in the physical characteristics of these two water masses it has become increasingly complex a water classification using the traditional approach with temperature, salinity and dissolved oxygen alone. Here, we show that an extended set of observed physical and biochemical parameters allows recognizing the existence of two different abyssal routes from the Adriatic source and one abyssal route from the Aegean source despite temperature and salinity of such two competing sources of abyssal water being virtually indistinguishable. Moreover, as the near-bottom development of exogenous bacterial communities transported by convectively-generated water masses in the abyss can provide a persistent trace of episodic events, intermittent flows like those generating abyssal waters in the Eastern Mediterranean basin may become detectable beyond the availability of concomitant measurements. PMID:26761666

  1. Biogeochemical, Isotopic and Bacterial Distributions Trace Oceanic Abyssal Circulation

    Science.gov (United States)

    Rubino, Angelo; Bensi, Manuel; Hainbucher, Dagmar; Zanchettin, Davide; Mapelli, Francesca; Ogrinc, Nives; Marchetto, Davide; Borin, Sara; Cardin, Vanessa; Fajon, Vesna; Horvat, Milena; Taricco, Carla; Baldi, Franco

    2016-01-01

    We explore the possibility of tracing routes of dense waters toward and within the ocean abyss by the use of an extended set of observed physical and biochemical parameters. To this purpose, we employ mercury, isotopic oxygen, biopolymeric carbon and its constituents, together with indicators of microbial activity and bacterial diversity found in bottom waters of the Eastern Mediterranean. In this basin, which has been considered as a miniature global ocean, two competing sources of bottom water (one in the Adriatic and one in the Aegean seas) contribute to the ventilation of the local abyss. However, due to a recent substantial reduction of the differences in the physical characteristics of these two water masses it has become increasingly complex a water classification using the traditional approach with temperature, salinity and dissolved oxygen alone. Here, we show that an extended set of observed physical and biochemical parameters allows recognizing the existence of two different abyssal routes from the Adriatic source and one abyssal route from the Aegean source despite temperature and salinity of such two competing sources of abyssal water being virtually indistinguishable. Moreover, as the near-bottom development of exogenous bacterial communities transported by convectively-generated water masses in the abyss can provide a persistent trace of episodic events, intermittent flows like those generating abyssal waters in the Eastern Mediterranean basin may become detectable beyond the availability of concomitant measurements. PMID:26761666

  2. Abyssalities against the grain: the clown circus without a future

    OpenAIRE

    Ludmila Lima Brandão; Daniel Pellegrim Sanchez

    2015-01-01

    By articulating Boaventura de Sousa Santos’ notion that the Western modern thinking is an abyssal thinking, we examine the functioning of such “abyssalities”, which hierarchize and turn knowledge and practices invisible, as well as operate the transmutation of old colonial domination (or colonialism) into coloniality in the visual arts system. Then we identify – as in the “coloniality of knowledge” – these same devices: the divisions in the reality of artistic production under an abyssal per...

  3. Internal wave structures in abyssal cataract flows

    Science.gov (United States)

    Makarenko, Nikolay; Liapidevskii, Valery; Morozov, Eugene; Tarakanov, Roman

    2014-05-01

    We discuss some theoretical approaches, experimental results and field data concerning wave phenomena in ocean near-bottom stratified flows. Such strong flows of cold water form everywhere in the Atlantic abyssal channels, and these currents play significant role in the global water exchange. Most interesting wave structures arise in a powerful cataract flows near orographic obstacles which disturb gravity currents by forced lee waves, attached hydraulic jumps, mixing layers etc. All these effects were observed by the authors in the Romanche and Chain fracture zones of Atlantic Ocean during recent cruises of the R/V Akademik Ioffe and R/V Akademik Sergei Vavilov (Morozov et al., Dokl. Earth Sci., 2012, 446(2)). In a general way, deep-water cataract flows down the slope are similar to the stratified flows examined in laboratory experiments. Strong mixing in the sill region leads to the splitting of the gravity current into the layers having the fluids with different densities. Another peculiarity is the presence of critical layers in shear flows sustained over the sill. In the case under consideration, this critical level separates the flow of near-bottom cold water from opposite overflow. In accordance with known theoretical models and laboratory measurements, the critical layer can absorb and reflect internal waves generated by the topography, so the upward propagation of these perturbations is blocked from above. High velocity gradients were registered downstream in the vicinity of cataract and it indicates the existence of developed wave structures beyond the sill formed by intense internal waves. This work was supported by RFBR (grants No 12-01-00671-a, 12-08-10001-k and 13-08-10001-k).

  4. Brain areas in abyssal demersal fishes.

    Science.gov (United States)

    Wagner, H J

    2001-06-01

    Four areas of the brain which receive primary projections from chemical senses ([1] olfactory bulb, [2] gustatory area including facial and vagal lobes), the eye ([3] optic tectum), and mechanosensory, and-hair-cell based systems i.e. the lateral line, vestibular and auditory systems ([4] trigeminal and octavolateral regions) have been studied and relative size differences used to make deductions on the sensory preferences of 35 fish species living on or near the bottom of the deep sea. Furthermore the relative volumes of the telencephalon and the corpus cerebelli were determined. Two evaluation modes were applied: (1) the relative mean of each system was calculated and species with above-average areas identified; (2) a cluster analysis established multivariate correlations among the sensory systems. The diversity of sensory brain areas in this population of fish suggests that the benthic and epibenthic environment of the abyss presents a rich sensory environment. Vision seems to be the single most important sense suggesting the presence of relevant bioluminescent stimuli. However, in combination the chemical senses, smell and taste, surpass the visual system; most prominent among them is olfaction. The trigeminal/octavolateral area indicating the role of lateral line input and possibly audition is also well represented, but only in association with other sensory modalities. A large volume telencephalon was often observed in combination with a prominent olfactory system, whereas cerebella of unusually large sizes occurred in species with above-average visual, hair-cell based, but also olfactory systems, confirming their role as multimodal sensorimotor coordination centers. In several species the predictions derived from the volumetric brain analyses were confirmed by earlier observations of stomach content and data obtained by baited cameras. PMID:11713385

  5. Suspended particulate studies over the Madeira Abyssal Plain

    International Nuclear Information System (INIS)

    Various aspects relating to suspended matter over the Madeira Abyssal Plain are discussed. Special attention is paid to the nepheloid layer including resuspension and transport processes; time variabilities in particle concentrations and fluxes; particle morphology, microbiology and chemical composition; phase association of metals. Also, tentative predictions of the behaviour of some radionuclides are made based on theory and data on rare earth elements. Instrumentation developed for the project is detailed - the deep water particle sampler. (author)

  6. Geothermal heating, diapycnal mixing and the abyssal circulation

    OpenAIRE

    J. Emile-Geay; Madec, G.

    2009-01-01

    The dynamical role of geothermal heating in abyssal circulation is reconsidered using three independent arguments. First, we show that a uniform geothermal heat flux close to the observed average (86.4 mW m−2) supplies as much heat to near-bottom water as a diapycnal mixing rate of ~10−4 m2 s−1 – the canonical value thought to be responsible for the magnitude of the presen...

  7. Direct observation of episodic growth in an abyssal xenophyophore (Protista)

    Science.gov (United States)

    Gooday, A. J.; Bett, B. J.; Pratt, D. N.

    1993-11-01

    Three specimens of the xenophyophore Reticulammina labyrinthica were photographed on the Madeira Abyssal Plain (31°6.1'N, 21°10.9'W; 4944 m) using the Bathysnap time-lapse camera system. During the 8 month observation period, the specimens underwent an estimated 3-10 fold increase in volume. Growth occurred episodically in several distinct phases, each lasting 2-3 days, during which sediment was collected and incorporated into the test. These phases were separated by fairly regular periods of about 2 months when the organisms showed little obvious activity. The growth phases were approximately synchronous between specimens. However, it is not clear whether the periodicity and apparent synchronization of these events resulted from an external (environmental) cue or whether growth is internally controlled and the synchronization arose by chance. These unique observations, which represent the first direct measurement of growth in any abyssal organism living outside a hydrothermal vent field, suggest that xenophyophores combine test growth with deposit feeding. The tests appear to grow more quickly, and to be more active, dynamic structures, than previously believed.

  8. From principles to practice: a spatial approach to systematic conservation planning in the deep sea.

    Science.gov (United States)

    Wedding, L M; Friedlander, A M; Kittinger, J N; Watling, L; Gaines, S D; Bennett, M; Hardy, S M; Smith, C R

    2013-12-22

    Increases in the demand and price for industrial metals, combined with advances in technological capabilities have now made deep-sea mining more feasible and economically viable. In order to balance economic interests with the conservation of abyssal plain ecosystems, it is becoming increasingly important to develop a systematic approach to spatial management and zoning of the deep sea. Here, we describe an expert-driven systematic conservation planning process applied to inform science-based recommendations to the International Seabed Authority for a system of deep-sea marine protected areas (MPAs) to safeguard biodiversity and ecosystem function in an abyssal Pacific region targeted for nodule mining (e.g. the Clarion-Clipperton fracture zone, CCZ). Our use of geospatial analysis and expert opinion in forming the recommendations allowed us to stratify the proposed network by biophysical gradients, maximize the number of biologically unique seamounts within each subregion, and minimize socioeconomic impacts. The resulting proposal for an MPA network (nine replicate 400 × 400 km MPAs) covers 24% (1 440 000 km(2)) of the total CCZ planning region and serves as example of swift and pre-emptive conservation planning across an unprecedented area in the deep sea. As pressure from resource extraction increases in the future, the scientific guiding principles outlined in this research can serve as a basis for collaborative international approaches to ocean management. PMID:24197407

  9. Last Glacial Maximum and deglacial abyssal seawater oxygen isotopic ratios

    Science.gov (United States)

    Wunsch, Carl

    2016-06-01

    An earlier analysis of pore-water salinity (chlorinity) in two deep-sea cores, using terminal constraint methods of control theory, concluded that although a salinity amplification in the abyss was possible during the LGM, it was not required by the data. Here the same methodology is applied to δ18Ow in the upper 100 m of four deep-sea cores. An ice volume amplification to the isotopic ratio is, again, consistent with the data but not required by it. In particular, results are very sensitive, with conventional diffusion values, to the assumed initial conditions at -100 ky and a long list of noise (uncertainty) assumptions. If the calcite values of δ18O are fully reliable, then published enriched values of the ratio in seawater are necessary to preclude sub-freezing temperatures, but the seawater δ18O in pore fluids does not independently require the conclusion.

  10. High resolution study of the spatial distributions of abyssal fishes by autonomous underwater vehicle

    OpenAIRE

    Milligan, R. J.; Morris, K. J.; Bett, B. J.; Durden, J. M.; Jones, D. O. B.; Robert, K; Ruhl, H. A.; Bailey, D. M.

    2016-01-01

    On abyssal plains, demersal fish are believed to play an important role in transferring energy across the seafloor and between the pelagic and benthic realms. However, little is known about their spatial distributions, making it difficult to quantify their ecological significance. To address this, we employed an autonomous underwater vehicle to conduct an exceptionally large photographic survey of fish distributions on the Porcupine Abyssal Plain (NE Atlantic, 4850 m water depth) encompassing...

  11. Long-term change in benthopelagic fish abundance in the abyssal northeast Pacific Ocean

    OpenAIRE

    Bailey, D. M.; Ruhl, H. A.; Smith, K

    2006-01-01

    Food web structure, particularly the relative importance of bottom-up and top-down control of animal abundances, is poorly known for the Earth's largest habitats: the abyssal plains. A unique 15-yr time series of climate, productivity, particulate flux, and abundance of primary consumers (primarily echinoderms) and secondary consumers (fish) was examined to elucidate the response of trophic levels to temporal variation in one another. Towed camera sled deployments in the abyssal northeast Pac...

  12. High resolution study of the spatial distributions of abyssal fishes by autonomous underwater vehicle

    OpenAIRE

    Milligan, R. J.; Morris, K. J.; Bett, B. J.; Durden, J. M.; Jones, D. O. B.; Robert, K; Ruhl, H. A.; Bailey, D. M.

    2016-01-01

    On abyssal plains, demersal fish are believed to play an important role in transferring energy across the seafloor and between the pelagic and benthic realms. However, little is known about their spatial distributions, making it difficult to quantify their ecological significance. To address this, we employed an autonomous underwater vehicle to conduct an exceptionally large photographic survey of fish distributions on the Porcupine Abyssal Plain (NE Atlantic, 4850?m water depth) encompassing...

  13. Abyssal Sequestration of Nuclear Waste in Earth's Crust

    Science.gov (United States)

    Germanovich, L. N.; Garagash, D.; Murdoch, L. C.; Robinowitz, M.

    2013-12-01

    This work outlines a new method for disposing of hazardous (e.g., nuclear) waste. The technique is called Abyssal Sequestration, and it involves placing the waste at extreme depths in Earth's crust where it could achieve the geologically-long period of isolation. Abyssal Sequestration involves storing the waste in hydraulic fractures driven by gravity, a process we term gravity fracturing. In short, we suggest creating a dense fluid (slurry) containing waste, introducing the fluid into a fracture, and extending the fracture downward until it becomes long enough to propagate independently. The fracture will continue to propagate downward to great depth, permanently isolating the waste. Storing solid wastes by mixing them with fluids and injecting them into hydraulic fractures is a well-known technology. The essence of our idea differs from conventional hydraulic fracturing techniques only slightly in that it uses fracturing fluid heavier than the surrounding rock. This difference is fundamental, however, because it allows hydraulic fractures to propagate downward and carry wastes by gravity instead of or in addition to being injected by pumping. An example of similar gravity-driven fractures with positive buoyancy is given by magmatic dikes that may serve as an analog of Abyssal Sequestration occurring in nature. Mechanics of fracture propagation in conditions of positive (diking) and negative (heavy waste slurry) buoyancy is similar and considered in this work for both cases. Analog experiments in gelatin show that fracture breadth (horizontal dimension) remains nearly stationary when fracturing process in the fracture 'head' (where breadth is 'created') is dominated by solid toughness, as opposed to the viscous fluid dissipation dominant in the fracture tail. We model propagation of the resulting 'buoyant' or 'sinking' finger-like fracture of stationary breadth with slowly varying opening along the crack length. The elastic response of the crack to fluid loading

  14. High resolution study of the spatial distributions of abyssal fishes by autonomous underwater vehicle.

    Science.gov (United States)

    Milligan, R J; Morris, K J; Bett, B J; Durden, J M; Jones, D O B; Robert, K; Ruhl, H A; Bailey, D M

    2016-01-01

    On abyssal plains, demersal fish are believed to play an important role in transferring energy across the seafloor and between the pelagic and benthic realms. However, little is known about their spatial distributions, making it difficult to quantify their ecological significance. To address this, we employed an autonomous underwater vehicle to conduct an exceptionally large photographic survey of fish distributions on the Porcupine Abyssal Plain (NE Atlantic, 4850 m water depth) encompassing two spatial scales (1-10 km(2)) on and adjacent to a small abyssal hill (240 m elevation). The spatial distributions of the total fish fauna and that of the two dominant morphotypes (Coryphaenoides sp. 1 and C. profundicolus) appeared to be random, a result contrary to common expectation but consistent with previous predictions for these fishes. We estimated total fish density on the abyssal plain to be 723 individuals km(-2) (95% CI: 601-844). This estimate is higher, and likely more precise, than prior estimates from trawl catch and baited camera techniques (152 and 188 individuals km(-2) respectively). We detected no significant difference in fish density between abyssal hill and plain, nor did we detect any evidence for the existence of fish aggregations at any spatial scale assessed. PMID:27180728

  15. High resolution study of the spatial distributions of abyssal fishes by autonomous underwater vehicle

    Science.gov (United States)

    Milligan, R. J.; Morris, K. J.; Bett, B. J.; Durden, J. M.; Jones, D. O. B.; Robert, K.; Ruhl, H. A.; Bailey, D. M.

    2016-05-01

    On abyssal plains, demersal fish are believed to play an important role in transferring energy across the seafloor and between the pelagic and benthic realms. However, little is known about their spatial distributions, making it difficult to quantify their ecological significance. To address this, we employed an autonomous underwater vehicle to conduct an exceptionally large photographic survey of fish distributions on the Porcupine Abyssal Plain (NE Atlantic, 4850 m water depth) encompassing two spatial scales (1–10 km2) on and adjacent to a small abyssal hill (240 m elevation). The spatial distributions of the total fish fauna and that of the two dominant morphotypes (Coryphaenoides sp. 1 and C. profundicolus) appeared to be random, a result contrary to common expectation but consistent with previous predictions for these fishes. We estimated total fish density on the abyssal plain to be 723 individuals km‑2 (95% CI: 601–844). This estimate is higher, and likely more precise, than prior estimates from trawl catch and baited camera techniques (152 and 188 individuals km‑2 respectively). We detected no significant difference in fish density between abyssal hill and plain, nor did we detect any evidence for the existence of fish aggregations at any spatial scale assessed.

  16. Abyssal Hill Segmentation: Quantitative analysis of the East Pacific Rise flanks 7°S-9°S

    Science.gov (United States)

    Goff, John A.; Malinverno, Alberto; Fornari, Daniel J.; Cochran, James R.

    1993-08-01

    The recent R/V Maurice Ewing EW9105 Hydrosweep survey of the East Pacific Rise (EPR) and adjacent flanks between 7°S and 9°S provides an excellent opportunity to explore the causal relationship between the ridge and the abyssal hills which form on its flanks. These data cover 100% of the flanking abyssal hills to 115 km on either side of the axis. We apply the methodology of Goff and Jordan (1988) for estimating statistical characteristics of abyssal hill morphology (rms height, characteristic lengths and widths, plan view aspect ratio, azimuthal orientation, and fractal dimension). Principal observations include the following: (1) the rms height of abyssal hill morphology is negatively correlated with the width of the 5- to 20-km-wide crestal high, consistent with the observations of Goff (1991) for northern EPR abyssal hill morphology; (2) the characteristic abyssal hill width displays no systematic variation with position relative to ridge segmentation within the EW9105 survey area, in contrast with observations of Goff (1991) for northern EPR abyssal hill morphology in which characteristic widths tend to be smallest at segment ends and largest toward the middle of segments; (3) abyssal hill rms heights and characteristic widths are very large just north of a counterclockwise rotating "nannoplate", suggesting that the overlap region is being pushed northward in response to microplate-style tectonics; and (4) within the 7°12'S-8°38'S segment, abyssal hill lineaments are generally parallel to the ridge axis, while south of this area, abyssal hill lineaments rotate with a larger "radius of curvature" than does the EPR axis approaching the EPR-Wilkes ridge-transform intersection.

  17. In situ experimental evidence of the fate of a phytodetritus pulse at the abyssal sea floor

    DEFF Research Database (Denmark)

    Witte, U.; Wenzhofer, F.; Sommer, S.; Boetius, A.; Heinz, P.; Aberle, N.; Sand, M.; Cremer, A.; Abraham, WR; Jørgensen, BB; Pfannkuche, O.

    2003-01-01

    quantified (over a period of 2.5 to 23 days) the response of an abyssal benthic community to a phytodetritus pulse, on the basis of 11 in situ experiments. Here we report that, in contrast to previous hypotheses(5-11), the sediment community oxygen consumption doubled immediately, and that macrofauna were...

  18. Quaternion hermitian planes

    OpenAIRE

    Stroppel, Markus

    1993-01-01

    The quaternion hermitian planes are defined, and are characterized by certain groups of automorphisms. For this purpose, characterizations of locally compact connected translation planes (in the context of stable planes) and compact connected projective desarguesian planes are given.

  19. New insights into the abyssal sponge fauna of the Kurile-Kamchatka plain and Trench region (Northwest Pacific)

    Science.gov (United States)

    Downey, Rachel V.; Janussen, Dorte

    2015-01-01

    The under-explored abyssal depths of the Kurile-Kamchatka region have been re-examined during the KuramBio (Kurile-Kamchatka Biodiversity Study) expedition. Combining new KuramBio data with previous expedition data in this region has enhanced our understanding abyssal sponge fauna, in particular, the patchiness, rarity, and exceptional richness of the Cladorhizidae family. In total, 14 sponge species, from 7 genera, in 5 families, within two classes (Demospongiae and Hexactinellida) were collected. Of the 14 species, 29% (4 spp.) have been found previously in this region, 36% (5 spp.) were new to the regional abyssal fauna, and 21% (3 spp.) were new to science. The number of abyssal species in this region has now been increased by 26% (8 spp.) and genera by nearly 15% (2 genera). Rarity is a prominent feature of this abyssal fauna, with more than half of species only found at one station, and 83% (19 spp.) of species found previously in this region were not re-found during KuramBio. Cladorhizid sponges dominate demosponge species and genera richness in the abyssal Kurile-Kamchatka region; accounting for 87% (20 spp.) of all demosponge species, and accounting for over 60% (5 genera) of all demosponge genera. Sponge richness in this region is potentially aided by the productivity of the ocean waters, the geological age of the Pacific Ocean, low population densities, and the varied topographic features (ridges, trenches, and seamounts) found in this region. Unusually, the dominance of demosponges in the Kurile-Kamchatka sponge faunal composition is not replicated in other well-sampled abyssal regions, which tend to be richer in deep-sea hexactinellid fauna. Broad depth, latitudinal and longitudinal ranges in Kurile-Kamchatka abyssal fauna are a key characteristic of this faunal assemblage. Strong abyssal faunal connectivity is found between the Kurile-Kamchatka region and North Pacific abyssal fauna, with weaker faunal connections found with the adjacent semi

  20. RRS Discovery Cruise 377 & 378, 05 - 27 Jul 2012, Southampton to Southampton. Autonomous ecological surveying of the abyss: understanding mesoscale spatical heterogeneity at the Porcupine Abyssal Plain

    OpenAIRE

    Ruhl, H.A.; et al, .

    2013-01-01

    Determining the distribution and abundance of life is challenging, especially in the deep sea where high pressure and other logistical challenges limit data availability to a tiny fraction of what is available for other systems. Most of Earth’s surface is nonetheless covered by water > 2000 m deep. Life in these abyssal regions influences the burial of carbon and nutrient cycling. Long-term research has now shown that even larger animals in the deep sea can vary in density by orders of magnit...

  1. Unique 16S rRNA sequences of Eurythenes gryllus (Crustacea: Amphipoda: Lysianassidae) from the Gulf of Mexico abyssal plain

    OpenAIRE

    Elva Escobar-Briones; Eduardo Nájera-Hillman; Fernando Álvarez

    2010-01-01

    Amphipods of the species Eurythenes gryllus were collected at 2 locations on the abyssal plain (~3 400 m) of the Gulf of Mexico in order to test whether or not these scavenger amphipods are isolated in this peripheral sea or show connectivity by their predominant swimming behavior, moving horizontally along the abyssal water masses in the region. Partial sequences of the mitochondrial 16S rRNA gene from 2 individuals of E. gryllus were determined and showed small differences when compared to ...

  2. RRS James Cook Cruise 62, 24 Jul-29 Aug 2011. Porcupine Abyssal Plain – sustained observatory research

    OpenAIRE

    Ruhl, H.A.; et al

    2012-01-01

    Science rationale for the activities comes from the fact that during the EU Framework programme IV project BENGAL (1996 to 1999) radical changes were noted in fauna living on the abyssal seafloor (Progress in Oceanography, Billett 2001). The changes appeared to be related to changes in upper ocean productivity and the flux of organic matter to the abyss (Wigham et al., 2003). Various hypotheses have been created concerning the effect of total organic carbon input, shown by Lampitt et al (2010...

  3. Encountering the Abyss: Deconstructing the Political Philosophy of Leo Strauss and the Straussian Interventions Relating to the Invasion of Iraq

    OpenAIRE

    Hirst, Agnes

    2010-01-01

    This thesis focuses on the figure of an abyss residing at the heart of metaphysics, and argues that thinking in light of its destabilising connotations opens up the possibility of attempting to take responsibility for the violence immanent to any and all politico-philosophical positions. It argues that this abyss represents a void or lack always already underpinning the attempt to posit universal or essential premises, and that it is precisely this lack which may be mobilised to unsettle the ...

  4. Phytopigments as biomarkers of selectivity in abyssal holothurians; interspecific differences in response to a changing food supply

    OpenAIRE

    FitzGeorge-Balfour, Tania; Billett, David S.M.; Wolff, George A.; Thompson, Anu; Tyler, Paul A.

    2010-01-01

    Holothurians dominate the abyssal megabenthos. They are key consumers and bioturbators of surficial sediment. Compounds essential for holothurian reproduction, such as carotenoids, are in short supply in the deep ocean. Holothurians cannot synthesise carotenoids de novo; the compounds are supplied with the flux of phytodetritus. Therefore, the supply of these compounds may play an important role in regulating processes on the seafloor. This study examines the link between the diet of abyssal ...

  5. Abyssal hills - hidden source of increased habitat heterogeneity, benthic megafaunal biomass and diversity in the deep sea

    Science.gov (United States)

    Durden, Jennifer M.; Bett, Brian J.; Jones, Daniel O. B.; Huvenne, Veerle A. I.; Ruhl, Henry A.

    2015-09-01

    Abyssal hills are the most abundant landform on Earth, yet the ecological impact of the resulting habitat heterogeneity on the wider abyss is largely unexplored. Topographic features are known to influence food availability and the sedimentary environment in other deep-sea habitats, in turn affecting the species assemblage and biomass. To assess this spatial variation, benthic assemblages and environmental conditions were compared at four hill and four plain sites at the Porcupine Abyssal Plain. Here we show that differences in megabenthic communities on abyssal hills and the adjacent plain are related to environmental conditions, which may be caused by local topography and hydrodynamics. Although these hills may receive similar particulate organic carbon flux (food supply from the surface ocean) to the adjacent plain, they differ significantly in depth, slope, and sediment particle size distribution. We found that megafaunal biomass was significantly greater on the hills (mean 13.45 g m-2, 95% confidence interval 9.25-19.36 g m-2) than the plain (4.34 g m-2, 95% CI 2.08-8.27 g m-2; ANOVA F(1, 6) = 23.8, p local sedimentary environment may be the mechanism driving these assemblage differences. Since the ecological heterogeneity provided by hills in the abyss has been underappreciated, regional assessments of abyssal biological heterogeneity and diversity may be considerably higher than previously thought.

  6. Towing large nets by single warp at abyssal depths I: methods

    International Nuclear Information System (INIS)

    In December, 1981, members of the School of Oceanography at Oregon State University towed a midwater rope trawl of about 107 m2 mouth area at abyssal and bathyal depths about 290 km west of Cape Mendocino, California. This was the first attempt to fish commercial-size nets at depths below 3000 meters. A total of 11 good otter trawl tows were obtained from 4300 m and 4 midwater trawl tows were made at depths from 2000-3100 m. The equipment and techniques required to tow commercial-size nets at bathyal and abyssal depths are described. The nets, doors and bridles of otter trawl and the midwater trawl are described. Depth monitors used are also described. The wire and winches used are also described, along with the difficulties encountered with gear failure. 7 references

  7. The absence of sharks from abyssal regions of the world's oceans.

    OpenAIRE

    Priede, I. G.; Froese, Rainer; Bailey, D. M.; Berkstad, O.A.; Collins, M A; Dyb, J.E.; Henriques, C.; Jones, E G; King, N.

    2006-01-01

    The oceanic abyss (depths greater than 3000 m), one of the largest environments on the planet, is characterized by absence of solar light, high pressures and remoteness from surface food supply necessitating special molecular, physiological, behavioural and ecological adaptations of organisms that live there. Sampling by trawl, baited hooks and cameras we show that the Chondrichthyes (sharks, rays and chimaeras) are absent from, or very rare in this region. Analysis of a global data set shows...

  8. On a simple empirical parameterization of topography-catalyzed diapycnal mixing in the abyssal ocean

    OpenAIRE

    Decloedt, T.; Luther, D.S.

    2010-01-01

    The global spatial distribution of the turbulent diapycnal diffusivity in the abyssal ocean is reexamined in light of the growing body of microstructure data revealing bottom-intensified turbulent mixing in regions of rough topography. A direct and nontrivial implication of the observed intensification is that the diapycnal diffusivity Kr, is depth dependent and patchily distributed horizontally across the world’s oceans. Theoretical and observational studies show that bottom-intensified mixi...

  9. Links between surface productivity and deep ocean particle flux at the Porcupine Abyssal Plain sustained observatory

    OpenAIRE

    Frigstad, H.; Henson, S. A.; Hartman, S. E.; A. M. Omar; E. Jeansson; Cole, H.; Pebody, C.; Lampitt, R. S.

    2015-01-01

    In this study we present hydrography, biogeochemistry and sediment trap observations between 2003 and 2012 at Porcupine Abyssal Plain (PAP) sustained observatory in the Northeast Atlantic. The time series is valuable as it allows for investigation of the link between surface productivity and deep ocean carbon flux. The region is a perennial sink for CO2, with an average uptake of around 1.5 mmol m−2 day−1. The average monthly drawdowns of inorganic carbon and nitrogen were used to...

  10. Demographic indicators of change in a deposit-feeding abyssal holothurian community (Station M, 4000 m)

    Science.gov (United States)

    Huffard, Christine L.; Kuhnz, Linda A.; Lemon, Larissa; Sherman, Alana D.; Smith, Kenneth L.

    2016-03-01

    Holothurians are among the most abundant benthic megafauna at abyssal depths, and important consumers and bioturbators of organic carbon on the sea floor. Significant fluctuations in abyssal holothurian density are often attributed to species-specific responses to variable particulate organic carbon flux (food supply) stemming from surface ocean events. We report changes in densities of 19 holothurian species at the abyssal monitoring site Station M in the northeast Pacific, recorded during 11 remotely operated vehicle surveys between Dec 2006 and Oct 2014. Body size demographics are presented for Abyssocucumis abyssorum, Synallactidae sp. 1, Paelopatides confundens, Elpidia sp. A, Peniagone gracilis, Peniagone papillata, Peniagone vitrea, Peniagone sp. A, Peniagone sp. 1, and Scotoplanes globosa. Densities were lower and species evenness was higher from 2006-2009 compared to 2011-2014. Food supply of freshly-settled phytodetritus was exceptionally high during this latter period. Based on relationships between median body length and density, numerous immigration and juvenile recruitment events of multiple species appeared to take place between 2011 and 2014. These patterns were dominated by elpidiids (Holothuroidea: Elasipodida: Elpidiidae), which consistently increased in density during a period of high food availability, while other groups showed inconsistent responses. We considered minimum body length to be a proxy for size at juvenile recruitment. Patterns in density clustered by this measure, which was a stronger predictor of maximum density than median and mean body length.

  11. Morphological, histochemical and immunohistochemical study of the gill epithelium in the abyssal teleost fish Coelorhynchus coelorhynchus.

    Science.gov (United States)

    Calabrò, Concetta; Albanese, Maria Pia; Lauriano, Eugenia Rita; Martella, Silvestro; Licata, Aurelio

    2005-01-01

    Histochemical and immunohistochemical study was carried out on nitrinergic innervation and neuroendocrine system in the gill epithelium of the abyssal fish Coelorhynchus coelorhynchus. The results showed that nNOS-positive nerve fibers, originating from the branchial arch were present in the subepithelial tissue of branchial primary filament. nNOS-positive neuroendocrine cells were also present in the primary filaments and secondary lamellae. Numerous mucous cells in the gill epithelium were AB/PAS-positive, while sialic acid was absent as confirmed by neuraminidase reaction and WGA lectin histochemistry. The mucus compounds in abyssal teleost fish are different from those found in pelagic species, being related to their living conditions. In abyssal species, greater numbers of chloride and neuroendocrine cells are involved in the movement of water and electrolytes. Neuroendocrine cells possess oxygen receptors which mediate the cardiovascular and ventilatory response to oxygen deficiency, as reported in teleost species. Besides, NO contributes through nervous stimulation to the regulation of vascular tone and blood circulation in the gill. PMID:15871563

  12. Abyssal Scavenging Communities attracted to Sargassum and fish in the Sargasso Sea

    Science.gov (United States)

    Fleury, Aharon G.; Drazen, Jeffrey C.

    2013-02-01

    Deep-sea communities rely on epipelagic surface production as a primary source of energy and food. The flux of phytodetritus drives many abyssal ecological processes but the flux of large particles such as nekton carcasses, macroalgae, and wood may also be important. Recent baited camera experiments noted that some abyssal fish consumed spinach and phytoplankton placed on the seafloor. To evaluate if fish or other scavengers would consume natural plant or macroalgal material falling to the deep-sea floor we conducted camera experiments using Sargassum or mackerel bait in the Sargasso Sea. A benthic community of invertebrates was attracted to Sargassum, which naturally falls to the seafloor in this area. In five instances it was observed that an isopod Bathyopsurus sp. removed a piece of Sargassum from the main clump and left the field of view with it. An ophiuroid is also observed handling a piece of Sargassum. The group of scavengers attracted to mackerel bait was very different and was dominated by large ophidiid fish. In contrast to studies elsewhere in the abyssal North Atlantic, only a small number of rattails are observed, which could be related to water depth or an ichthyofaunal zonal change between oligotrophic and eutrophic regions.

  13. Controls on melting at spreading ridges from correlated abyssal peridotite - mid-ocean ridge basalt compositions

    Science.gov (United States)

    Regelous, Marcel; Weinzierl, Christoph G.; Haase, Karsten M.

    2016-09-01

    Variations in the volume and major element composition of basalt erupted along the global mid-ocean ridge system have been attributed to differences in mantle potential temperature, mantle composition, or plate spreading rate and lithosphere thickness. Abyssal peridotites, the residues of mantle melting beneath mid-ocean ridges, provide additional information on the melting process, which could be used to test these hypotheses. We compiled a global database of abyssal peridotite compositions averaged over the same ridge segments defined by Gale et al. (2013). In addition, we calculated the distance of each ridge segment to the nearest hotspots. We show that Cr# in spinel in abyssal peridotites is negatively correlated with Na90 in basalts from the same ridge segments on a global scale. Ridge segments that erupt basalts apparently produced by larger degrees of mantle melting are thus underlain by peridotites from which large amounts of melt have been extracted. We find that near-ridge hotspots have a more widespread influence on mid-ocean ridge basalt (MORB) composition and ridge depth than previously thought. However, when these hotspot-influenced ridge segments are excluded, the remaining segments show clear relationships between MORB composition, peridotite composition, and ridge depth with spreading rate. Very slow-spreading ridges (<20 mm/yr) are deeper, erupt basalts with higher Na90, Al90, K90/Ti90, and lower Fe90, Ca90/Al90, and expose peridotites with lower Cr# than intermediate and fast-spreading ridges. We show that away from hotspots, the spreading-rate dependence of the maximum degree of mantle melting inferred from Cr# in peridotites (FM) and the bulk degree of melting inferred from Na90 in basalts (FB) from the same ridge segments is unlikely to be due to variations in mantle composition. Nor can the effects of dynamic mantle upwelling or incomplete melt extraction at low spreading rates satisfactorily explain the observed compositions of abyssal

  14. Euclid Squares on Infinite Planes

    OpenAIRE

    W.B.Vasantha Kandasamy; Ilanthenral, K.; Florentin Smarandache

    2015-01-01

    In this book for the first time the authors study the new type of Euclid squares in various planes like real plane, complex plane, dual number plane, special dual like number plane and special quasi dual number plane.

  15. Glacial magnetite dissolution in abyssal NW Pacific sediments - evidence for carbon trapping?

    Science.gov (United States)

    Korff, Lucia; von Dobeneck, Tilo; Frederichs, Thomas; Kasten, Sabine; Kuhn, Gerhard; Gersonde, Rainer; Diekmann, Bernhard

    2016-04-01

    The abyssal North Pacific Ocean's large volume, depth, and terminal position on the deep oceanic conveyor make it a candidate site for deep carbon trapping as postulated by climate theory to explain the massive glacial drawdown of atmospheric CO2. As the major basins of the North Pacific have depths of 5500-6500m, far below the modern and glacial Calcite Compensation Depths (CCD), these abyssal sediments are carbonate-free and therefore not suitable for carbonate-based paleoceanographic proxy reconstructions. Instead, paleo-, rock and environmental magnetic methods are generally well applicable to hololytic abyssal muds and clays. In 2009, the international paleoceanographic research cruise SO 202 INOPEX ('Innovative North Pacific Experiment') of the German RV SONNE collected two ocean-spanning EW sediment core transects of the North Pacific and Bering Sea recovering a total of 50 piston and gravity cores from 45 sites. Out of seven here considered abyssal Northwest Pacific piston cores collected at water depths of 5100 to 5700m with mostly coherent shipboard susceptibility logs, the 20.23m long SO202-39-3, retrieved from 5102 m water depth east of northern Shatsky Rise (38°00.70'N, 164°26.78'E), was rated as the stratigraphically most promising record of the entire core transect and selected for detailed paleo- and environmental magnetic, geochemical and sedimentological investigations. This core was dated by correlating its RPI and Ba/Ti records to well-dated reference records and obviously provides a continuous sequence of the past 940 kyrs. The most striking orck magnetic features are coherent magnetite-depleted zones corresponding to glacial periods. In the interglacial sections, detrital, volcanic and even submicron bacterial magnetite fractions are excellently preserved. These alternating magnetite preservation states seem to reflect dramatic oxygenation changes in the deep North Pacific Ocean and hint at large-scale benthic glacial carbon trapping

  16. Unexpectedly higher metazoan meiofauna abundances in the Kuril-Kamchatka Trench compared to the adjacent abyssal plains

    Science.gov (United States)

    Schmidt, Christina; Martínez Arbizu, Pedro

    2015-01-01

    We studied meiofauna standing stocks and community structure in the Kuril-Kamchatka Trench and its adjacent abyssal plains in the northwestern Pacific Ocean. In general, the Nematoda were dominant (93%) followed by the Copepoda (4%). Nematode abundances ranged from 87% to 96%; those of copepods from 2% to 7%. The most diverse deployment yielded 17 taxa: Acari, Amphipoda, Annelida, Bivalvia, Coelenterata, Copepoda, Cumacea, Gastrotricha, Isopoda, Kinorhyncha, Loricifera, Nematoda, Ostracoda, Priapulida, Tanaidacea, Tantulocarida, and Tardigrada. Nauplii were also present. Generally, the trench slope and the southernmost deployments had the highest abundances (850-1392 individuals/cm2). The results of non-metric multidimensional scaling indicated that these deployments were similar to each other in meiofauna community structure. The southernmost deployments were located in a zone of higher particulate organic carbon (POC) flux (g Corg m-2 yr-1), whereas the trench slope should have low POC flux due to depth attenuation. Also, POC and abundance were significantly correlated in the abyssal plains. This correlation may explain the higher abundances at the southernmost deployments. Lateral transport was also assumed to explain high meiofauna abundances on the trench slope. Abundances were generally higher than expected from model results. ANOSIM revealed significant differences between the trench slope and the northern abyssal plains, between the central abyssal plains and the trench slope, between the trench slope and the southern abyssal plains, between the central and the southern abyssal plains, and between the central and northern deployments. The northern and southern abyssal plains did not differ significantly. In addition, a U-test revealed highly significant differences between the trench-slope and abyssal deployments. The taxa inhabited mostly the upper 0-3 cm of the sediment layer (Nematoda 80-90%; Copepoda 88-100%). The trench-slope and abyssal did not differ

  17. Long-term maintenance and public exhibition of deep-sea hydrothermal fauna: The AbyssBox project

    Science.gov (United States)

    Shillito, Bruce; Ravaux, Juliette; Sarrazin, Jozée; Zbinden, Magali; Sarradin, Pierre-Marie; Barthelemy, Dominique

    2015-11-01

    The AbyssBox project aims to provide the first permanent public exhibition of live deep-sea hydrothermal fauna maintained at in situ pressure. AbyssBox is a pressurized aquarium designed to function permanently. Here we present details of the project after the public exhibition functioned for more than three years at Océanopolis aquarium in Brest, France. We also describe the AbyssBox pressure aquarium, and provide data and observations on vent shrimp (Mirocaris fortunata) and crabs (Segonzacia mesatlantica) that were sampled from 1700 m depth at the Lucky Strike vent field (Mid-Atlantic Ridge) during different cruises. While mortalities exceeded 50% during the first days following sampling, the remaining animals appeared to acclimate fairly well. Some crabs have now been kept for more than 2 years, and some shrimp have spent more than 3 years in captivity. Primarily designed for a public exhibition, the AbyssBox is already used for scientific purposes, since it provides one of the most effective tools for long-term rearing of deep-sea fauna. AbyssBox is a first step towards maintaining a variety of deep-sea fauna year-round at in situ pressure, which will serve both scientific and public interests.

  18. A comparison of benthic infaunal abundance on two abyssal plains in the northeast Pacific Ocean

    Science.gov (United States)

    Carey, Andrew G.

    1981-05-01

    Benthic macro-infauna were sampled in the northeast Pacific Ocean at 12 stations on an east-west transect across Cascadia and Eastern Tufts abyssal plains to determine ecological effects of continental influences and depth on those communities. The two plains, separated by the East Pacific Rise, differ in depth and distance from the continental margin. Tufts Plain lies to the west; primary production in the overlying water and the amount of organic carbon in the surface sediments are lower than for the Cascadia Plain region. Five benthic ecological zones were distinguished: (1) Cascadia Plain Slope-Base; (2) Eastern Cascadia Plain; (3) Cascadia Deep-Sea Channel; (4) Western Cascadia Plain; and (5) Eastern Tufts Plain. These differ in faunal biomass, numerical density, gross composition of the fauna by phyla, and composition of sediment. Comparatively, the slope-base environment supports the most abundant fauna. The numerical density of infauna on Eastern Tufts Plain is similar to that on Eastern and Western Cascadia Plain; however, the biomass tends to be lower in the deeper, more distant environment. It is concluded that these differences in the benthic fauna are probably caused by varying levels of input from primary production in overlying waters and differences in the transport of organic-rich particles off the continental shelf. Distance-related environmental characteristics are shown to be critical in the deep sea for controlling benthic community structure. On Cascadia Abyssal Plain, a plateau-like feature, the gross structure of communities changes with increasing distance from the continent but at constant depth. Faunal densities, biomass, and composition by phyla lie within the range of values normally associated with upper abyssal environments.

  19. Moored observations of episodic abyssal flow and mixing at station ALOHA

    Science.gov (United States)

    Alford, M. H.; Lukas, Roger; Howe, Bruce; Pickering, Andy; Santiago-Mandujano, Fernando

    2011-08-01

    Moored measurements of abyssal velocity and temperature are presented with a focus on episodic cold overflow events first observed by Lukas et al. (2001) in the Hawaii Ocean Time-series (HOT), a 23-year-long time series of ≈ monthly CTD profiles at station ALOHA (22.75°N, 158°W). Three major cold events were observed in our 2.5-year record, of which we present one in detail. The event appeared in two pulses spaced by about two weeks, wherein potential temperature anomaly was <-0.015°C over the bottom 600 m. Flow was about 10 cms-1 to the southwest, confirming earlier interpretations of the events as overflows from the Maui deep to the east. Between the two pulses, flow veered to the northwest, possibly associated with seiching. Speed decreased rapidly below the sill depth (≈4625) m, suggesting sheltering by the basin walls. The associated shear, even smoothed over 200 m and not including internal waves, was nearly unstable to Kelvin-Helmholtz instability. During this period, a large mixed region was observed wherein the lower 240 m was homogenized, remaining so for 14 hours (1.2 buoyancy periods). From Thorpe scale analysis, the implied diffusivity of the event was (0.5-4.5) × 10-1m2s-1. No other overturning events greater than 50 m high were observed in the record, suggesting that abyssal mixing is strongly intermittent. We suggest that such intermittency in abyssal mixing and flow is likely the rule rather than the exception, calling for more highly temporally resolved observations.

  20. Seawater-derived rare earth element addition to abyssal peridotites during serpentinization

    Science.gov (United States)

    Frisby, Carl; Bizimis, Michael; Mallick, Soumen

    2016-04-01

    Serpentinized abyssal peridotites are evidence for active communication between the Earth's hydrosphere and the upper mantle, where exchange and retention of both major and trace elements occur. Bulk rock Nd isotopes in serpentinized abyssal peridotites imply interaction of seawater with the peridotite. In contrast, the Nd isotopes of clinopyroxenes from serpentinized abyssal peridotites retain their primary magmatic signature. It is currently unclear if, how and where seawater-derived Nd and other REE are being added or exchanged with the mantle peridotite minerals during serpentinization. To remedy this knowledge gap, we present in situ trace and major element concentrations, bulk rock and sequential leaching experiment trace element concentrations as well as Nd, Sr isotope data on refertilized and depleted serpentinized abyssal peridotites from the Southwest Indian Ridge. The secondary serpentine matrix and magnetite veins in these peridotites have elevated LREE concentrations, with variable negative Ce anomalies and large Rb, Sr, Pb and U enrichments that resemble seawater trace element patterns. The LREE concentrations in the serpentine phase are higher than those expected for the primary mantle mineralogy (olivine, orthopyroxene) based on data from relic clinopyroxenes and equilibrium partition coefficients. These data are consistent with seawater-derived REE addition to the peridotite during serpentinization. The bulk rocks have more radiogenic Sr and more unradiogenic Nd isotopes than their clinopyroxene (up to 8 εNd units lower than clinopyroxene). Sequential leaching experiments designed to mobilize secondary carbonates and Fe-oxides show even more unradiogenic Nd isotope ratios in the leachates than the bulk rock and clinopyroxene, approaching seawater compositions (up to 15 εNd units lower than clinopyroxene). Mass balance calculations using trace elements or Nd isotopes suggest that up to 30% of the bulk peridotite Nd budget is of seawater origin and

  1. Lighter and stronger planes

    OpenAIRE

    Attard, Bonnie; Duca, Edward

    2015-01-01

    The price of fuel is a large cost burden on the aerospace industry. A lighter plane means cheaper flights, increased aircraft range, and less environmental pollution. http://www.um.edu.mt/think/lighter-and-stronger-planes/

  2. Comparative geoscience studies of the Madeira and Southern Nares Abyssal Plains: NEA/SWG preference location document

    Energy Technology Data Exchange (ETDEWEB)

    Auffret, G.A.; Buckley, D.E.; Schuttenhelm, R.T.E.; Searle, R.C.; Shephard, L.E.; Cranston, R.E.

    1986-01-01

    This document summarizes the status of geoscience investigations in the two primary North Atlantic study locations Great Meteor East (GME) in the Madeira Abyssal Plain, and the Southern Nares Abyssal Plain (SNAP), and assesses the characteristics of these locations relative to the guidelines considered desirable and necessary for a potential subseabed high-level waste repository. These characteristics will be continually reevaluated as additional data become available and as our understanding of deep-sea sediment processes within abyssal plain environments improves. Initially, a number of areas of minimum size were identified in the ocean basins that appeared to comply with most of the stability and barrier guidelines. However, detailed studies in both GME and SNAP demonstrate that as our level of knowledge improves, and the degree of resolution increases, the number of 100 km/sup 2/ areas complying with these guidelines becomes much more limited. This observation may be characteristic of abyssal plain and abyssal hill environments in both the North Atlantic and North Pacific basins. Marked differences in geoscience characteristics exist between the Great Meteor East and the Southern Nares Abyssal Plain study locations. The significance of these differences, as they impact the selection of a single preferred site for a potential subseabed repository, can only be determined by using an integrated systems risk assessment modeling approach. The known geoscience characteristics can, however, be used in conjunction with the site assessment guidelines to draw conclusions concerning the geoscience suitability of these two locations. These conclusions will be modified as specific types of data from future expeditions become available.

  3. The absence of sharks from abyssal regions of the world's oceans.

    Science.gov (United States)

    Priede, Imants G; Froese, Rainer; Bailey, David M; Bergstad, Odd Aksel; Collins, Martin A; Dyb, Jan Erik; Henriques, Camila; Jones, Emma G; King, Nicola

    2006-06-01

    The oceanic abyss (depths greater than 3000 m), one of the largest environments on the planet, is characterized by absence of solar light, high pressures and remoteness from surface food supply necessitating special molecular, physiological, behavioural and ecological adaptations of organisms that live there. Sampling by trawl, baited hooks and cameras we show that the Chondrichthyes (sharks, rays and chimaeras) are absent from, or very rare in this region. Analysis of a global data set shows a trend of rapid disappearance of chondrichthyan species with depth when compared with bony fishes. Sharks, apparently well adapted to life at high pressures are conspicuous on slopes down to 2000 m including scavenging at food falls such as dead whales. We propose that they are excluded from the abyss by high-energy demand, including an oil-rich liver for buoyancy, which cannot be sustained in extreme oligotrophic conditions. Sharks are apparently confined to ca 30% of the total ocean and distribution of many species is fragmented around sea mounts, ocean ridges and ocean margins. All populations are therefore within reach of human fisheries, and there is no hidden reserve of chondrichthyan biomass or biodiversity in the deep sea. Sharks may be more vulnerable to over-exploitation than previously thought. PMID:16777734

  4. Long-term change in benthopelagic fish abundance in the abyssal northeast Pacific Ocean.

    Science.gov (United States)

    Bailey, D M; Ruhl, H A; Smith, K L

    2006-03-01

    Food web structure, particularly the relative importance of bottom-up and top-down control of animal abundances, is poorly known for the Earth's largest habitats: the abyssal plains. A unique 15-yr time series of climate, productivity, particulate flux, and abundance of primary consumers (primarily echinoderms) and secondary consumers (fish) was examined to elucidate the response of trophic levels to temporal variation in one another. Towed camera sled deployments in the abyssal northeast Pacific (4100 m water depth) showed that annual mean numbers of the dominant fish genus (Coryphaenoides spp.) more than doubled over the period 1989-2004. Coryphaenoides spp. abundance was significantly correlated with total abundance of mobile epibenthic megafauna (echinoderms), with changes in fish abundance lagging behind changes in the echinoderms. Direct correlations between surface climate and fish abundances, and particulate organic carbon (POC) flux and fish abundances, were insignificant, which may be related to the varied response of the potential prey taxa to climate and POC flux. This study provides a rare opportunity to study the long-term dynamics of an unexploited marine fish population and suggests a dominant role for bottom-up control in this system. PMID:16602284

  5. Evidence for deep-water deposition of abyssal Mediterranean evaporites during the Messinian salinity crisis

    Science.gov (United States)

    Christeleit, Elizabeth C.; Brandon, Mark T.; Zhuang, Guangsheng

    2015-10-01

    Scientific drilling of the abyssal evaporites beneath the deepest parts of the Mediterranean basin gave rise to the idea that the Mediterranean sea completely evaporated at the end of the Messinian. Herein, we show, using new organic geochemical data, that those evaporites were deposited beneath a deep-water saline basin, not in a subaerial saltpan, as originally proposed. Abundant fossil organic lipids were extracted from evaporites in Mediterranean Deep Sea Drilling Project cores. The archaeal lipid distribution and new analyses, using the ACE salinity proxy and TEX86 temperature proxy, indicate that surface waters at the time of evaporite deposition had normal marine salinity, ranging from ∼26 to 34 practical salinity units, and temperatures of 25-28 °C. These conditions require a deep-water setting, with a mixed layer with normal marine salinity and an underlying brine layer at gypsum and halite saturation. After correction for isostatic rebound, our results indicate maximum drawdown of ∼2000 m and ∼2900 m relative to modern sea level in the western and eastern Mediterranean basins, respectively. Our results are consistent with previously proposed scenarios for sea level drawdown based on both subaerial and submarine incision and backfilling of the Rhone and Nile rivers, which require Messinian sea level drops of ∼1300 m and ∼200 m, respectively. This study provides new evidence for an old debate and also demonstrates the importance of further scientific drilling and sampling of deeper part of the abyssal Messinian units.

  6. Moored current meter data from the Madeira Abyssal Plain (GME). 1. deployment (1984)

    International Nuclear Information System (INIS)

    Near bottom current have been measured at three closely spaced sites in the N.E. Atlantic for 13 months. Locations were selected in the Great Meteor East study site area, near 310 30'N 250W, one on the abyssal plain, one on top of a small abyssal hill about 400 m high and one on its flank just above the plain. Current meters were moored 10, 100, and 1000 m above the local bottom (5438 m, 5398 m and 4999 m) in January 1984 and recovered in February 1985. This report displays the characteristics of the currents in numerous tables and figures. In the mean they ar found to be very weak and though adjacent moorings are separated by only 12 km and 27 km the year-long current directions differ radically. Current variations are principally due to semi-diurnal tides, inertial oscillations and eddies the latter of which migrate over the moorings. The tidal energy meets expectations as does the eddy energy with magnitude 2-3 cm2 s-2. Horizontal (isopycnal) diffusivity is estimated as about 2x102 m2 s-1. Currents 10 m above the bottom exceed 10 cm/s least frequently on the plain and most frequently at the hill-foot. The influence of the hill is surprisingly large. At all three sites the strongest currents are found near the sea bed. Speeds also show a Weibull distribution and rough 50 year return currents are inferred. (author)

  7. Moored current meter data from the Madeira Abyssal Plain (GME). 2. deployment (1984)

    International Nuclear Information System (INIS)

    Near bottom currents have been measured at three closely spaced sites in the N.E. Atlantic for 22 months. This report describes the results for the period 13-22 months and closely follows the pattern used in describing the first 13 months of data (IOS Report No. 221, 1986). The three locations were in the Great Meteor East study site area, near 310 30'N 250W, one on the abyssal plain, one on top of a small abyssal hill about 400 m high and one on its eastern flank. For the period of this report current meters were moored 10,100 and 1000 m above the local bottom (5438 m, 5433 m and 4989 m) between February and November 1985. The characteristics of the currents are displayed in numerous tables and figures: the mean currents for the 9 months are strikingly similar to those measured for the first 13 months. The variations in current strengths are also similar and yield eddy energies of between 2 and 3 cm2 s-2 and horizontal (isopycnal) diffusivity of 2x102 m2 s-1. Currents in excess of 10 cm/s were considerably less frequent than found for the earlier data set. (author)

  8. Major Elements Budget Between Abyssal Peridotite And Seawater During The Serpentinization

    Science.gov (United States)

    Yu, X.; Dong, Y.; Li, X.; Chu, F.

    2012-12-01

    Water-Rock Interaction is one of the most hot-debated issues among geologists, geophysicists, as well as geochemists. Abyssal peridotites recovered from the seafloor are often greatly affected or alterated by seawater in the form of serpentinization. The alteration to the peridotites makes it difficult to do the straightforward analysis for its primary composition as it was settled in the upper mantle, which confine the usage of these rare direct samples from the mantle in the scientific study, such as mantle dynamics, mantle composition and crust-mantle interaction. Besides, It was revealed recently that the serpentinization of abyssal peridotites may give birth to the hydrothermal activity. The elements migration during the serpentinization may perform a great role on the chemical composition of the hydrothermal fluid, which can support a hidden chemosynthetic ecosystem in the abyssal seabed. The research work focused on the major elements behavior during the serpentinization by studying the partially serpentinized samples of abyssal peridotite from Southwest Indian Ridge. The primary mineral assemblage of peridotite is olivine (Mg2SiO4), orthopyroxene (Mg2Si2O6), clinopyroxene (CaMgSi2O6) and spinel ((Mg,Fe)(Al,Cr)2O4). The major chemical composition are usually as SiO2 (30~45wt.%), MgO (20~45 wt.%), FeO and Fe2O3 (total 5~15 wt.%). Besides there are very few MnO, CaO, Al2O3, Cr2O3, NiO, Na2O, K2O and H2O. While on the other hand the serpentinized peridotite shows a more complicated mineral assemblage, besides the primary minerals there are more alteration minerals, such as serpentine (Mg3[Si2O5](OH)4), magnetite (Fe3O4), talc (Mg3[Si4O10](OH)2), brucite (Mg(OH)2), tremolite (Ca2Mg5[Si8O22](OH)2), chromite (FeCr2O4), chlorite ((Mg,Fe)6[(Si,Al)4O10](OH)8), and other accessary minerals like native metals, sulfides, clay minerals and hornblende. According to the EMPA analysis, the serpentinized sample shows the chemical composition as SiO2(~40 wt.%), MgO(~30 wt

  9. Three new species of deep-sea Gromia (Protista, Rhizaria) from the bathyal and abyssal Weddell Sea, Antarctica

    DEFF Research Database (Denmark)

    Rothe, Nina; Gooday, Andrew J.; Cedhagen, Tomas; Fahrni, José; Hughes, J. Alan; Page, Anton; Pearce, Richard B.; Pawlowski, Jan

    2009-01-01

    We describe three new species of the genus Gromia from bathyal and abyssal depths in the Weddell Sea. The new species are characterized by a combination of morphological and molecular criteria. All three species possess a distinct oral capsule and a layer of ‘honeycomb membranes’, which form the ...

  10. Rich and rare—First insights into species diversity and abundance of Antarctic abyssal Gastropoda (Mollusca)

    Science.gov (United States)

    Schwabe, Enrico; Michael Bohn, Jens; Engl, Winfried; Linse, Katrin; Schrödl, Michael

    2007-08-01

    The abyssal depths of the polar oceans are thought to be low in diversity compared with the shallower polar shelves and temperate and tropical deep-sea basins. Our recent study on the gastropod fauna of the deep Southern Ocean gives evidence of the existence of a rich gastropod assemblage at abyssal depths. During the ANDEEP I and II expeditions to the southern Drake Passage, Northwestern Weddell Sea, and South Sandwich Trench, gastropods were collected by bottom and Agassiz trawls, epibenthic sledge, and multicorer, at 40 stations in depths between 127 and 5194 m. On the whole, 473 specimens, corresponding to 93 species of 36 families, were obtained. Of those, 414 specimens were caught below 750 m depth and refer to 84 (90%) benthic species of 32 (89%) families. Most families were represented by a single species only. The numerically dominant families were Skeneidae and Buccinidae (with 10 and 11 species, respectively), Eulimidae and Trochidae (with 9 species each), and Turridae (6 species). Thirty-Seven benthic deep-sea species (44%) were represented by a single specimen, and another 20 species (24%) were found at a single station, suggesting that more than two thirds of Antarctic deep-sea gastropod species are very rare or have a very scattered distribution. Of the 27 species occurring at two or more deep-sea stations, 14 were collected with different gear. Approximately half of the deep-water species are new to science or have been recently described. The present investigation increases the total number of recorded benthic Antarctic deep-sea gastropods (below 750 m) from 115 to 177. The previously known depth ranges have been extended, often considerably, for 31 species. The collected deep-sea gastropods comprise both eurybathic shelf species (29%) and apparently true deep-sea species (58%); some of the latter may belong to a so far unknown Antarctic abyssal fauna. Geographical ranges of the collected Antarctic benthic deep-sea gastropod species appear limited

  11. Engineering concepts for the placement of wastes on the abyssal seafloor

    Science.gov (United States)

    Valent, Philip J.; Palowitch, Andrew W.; Young, David K.

    1998-05-01

    The Naval Research Laboratory (NRL), with industry and academic participation, has completed a study of the concept of isolating industrial wastes (i.e., sewage sludge, fly ash from municipal incinerators, and dredged material) on the abyssal seafloor. This paper presents results of the technical and economic assessment of this waste management concept. The results of the environmental impacts portion of the study are presented in a companion paper. The technical assessment began with identification of 128 patents addressing waste disposal in the ocean. From these 128 patents, five methods for transporting wastes through the water column and emplacing wastes within an easily monitored area on the abyssal seafloor were synthesized for technical assessment. In one method waste is lowered to the seafloor in a bucket of 190 m 3. In a second method waste is pumped down to the seafloor in pipes, 1.37 m in diameter and 6100 m in length. In a third method waste is free-fallen from the ocean surface in 380-m 3 geosynthetic fabric containers (GFCs). In the fourth and fifth methods, waste is carried to near the seafloor in GFCs transported in (a) a 20,000 metric ton displacement (loaded), unpowered, unmanned submersible glider, or (b) a 2085 metric ton displacement (loaded) disk-shaped transporter traversing to and from the seafloor much like an untethered elevator. In the last two methods the transporter releases the GFCs to free-fall the last few hundred meters to the seafloor. Two reliability analyses, a Fault Tree Analysis (FTA), and a Failure Modes, Effects, and Criticality Analysis (FMECA), showed that the free-fall GFC method posed the least overall relative risk, provided that fabric container and transporter designs eliminate the potential for tearing of the containers on release from the surface transporter. Of the five methods, the three GFC methods were shown to offer cost-effective waste management options when compared with present-day waste management

  12. Implications of spinel compositions for the petrotectonic history of abyssal peridotite from Southwest Indian Ridge (SWIR)

    Science.gov (United States)

    Chen, T.; Jin, Z.; Wang, Y.; Tao, C.

    2012-12-01

    Abyssal peridotites generate at mid-ocean ridges. Lherzolite and harzburgite are the main rock types of peridotites in the uppermost mantle. The lherzolite subtype, less depleted and less common in ophiolites, characterizes mantle diapirs and slow-spreading ridges. Along the Earth's mid-ocean ridges, abyssal peridotites undergo hydration reactions to become serpentinite minerals, especially in slow to ultraslow spreading mid-ocean ridges. Spinel is common in small quantities in peridotites, and its compositions have often been used as petrogenetic indicators [1]. The Southwest Indian Ridge (SWIR) is one of the two ultraslow spreading ridges in the world. The studied serpentinized peridotite sample was collected by the 21st Voyage of the Chinese oceanic research ship Dayang Yihao (aka Ocean No. 1) from a hydrothermal field (63.5°E, 28.0°S, and 3660 m deep) in SWIR. The studied spinels in serpentinized lherzolite have four zones with different compositions: relic, unaltered core is magmatic Al-spinels; micro- to nano- sized ferrichromite zoned particles; narrow and discontinuous magnetite rim; and chlorite aureoles. The values Cr# of the primary Al-spinels indicate the range of melting for abyssal peridotites from SWIR extends from ~4% to ~7% [2]. The alteration rims of ferrichromite have a chemical composition characterized by Fe enrichment and Cr# increase indicating chromite altered under greenschist-amphibolite facies. Magnetites formed in syn- and post- serpentinization. Chlorite (clinochlore) formed at the boundary and crack of spinel indicating it had undergone with low-temperature MgO- and SiO2-rich hydrothermal fluids [3]. It suggests that serpentinized lherzolite from SWIR had undergone poly-stage hydration reactions with a wide range of temperature. Acknowledgments: EMPA experiment was carried out by Xihao Zhu and Shu Zheng in The Second Institute of Oceanography and China University of Geosciences, respectively. The work was supported by NSFC

  13. Kuril-Kamchatka deep sea revisited - insights into the amphipod abyssal fauna

    Science.gov (United States)

    Jażdżewska, Anna

    2015-01-01

    During the KuramBIO expedition to the Kuril-Kamchatka Trench and abyssal plain, benthic samples from the depths from 4987 to 5422 m were collected using a camera-epibenthic sledge. In this collection more than 1200 individuals of Amphipoda were found. They were assigned to 60 taxa (including 47 morphospecies) and 21 families. Until now 28 species being new to science have been found: six in the superfamily Eusiroidea and in the Oedicerotidae and Synopiidae families, four in the Phoxocephalidae, three in the Pardaliscidae, two in the Stenothoidae and one in the Pachynidae. The Synopiidae, Stenothoidae and Pachynidae were recorded for the first time in North-West Pacific area. The dominant and most speciose families were Oedicerotidae, Phoxocephalidae, Synopiidae, Eusiridae s.l. and Lysianassidae. The cluster analysis clearly separated the shallowest sample from the others, which were divided further into two groups. The shallowest sample was characterized by the highest number of species and number of individuals.

  14. Heat flow measurements in Great Meteor East, Madeira Abyssal Plain, during Discovery Cruise 144

    International Nuclear Information System (INIS)

    This report describes 21 closely spaced heat flow measurements which were made along two survey lines in an area of faulted sediments east of Great Meteor Seamount in the Madeira Abyssal Plain. The heat flow was found to be correlated with basement topography as mapped by seismic reflection profiling. Data modelling suggests that this is due both to the thermal conductivity contrast between sediments and basement rocks and to the presence of hydrothermal circulation within basement highs. The existence of non-linear temperature profiles in sediments covering basement highs suggests that the underlying circulation is causing an upward movement of porewater. There is no firm evidence to show that the sediment faults act as preferred pathways for porewater advection. (author)

  15. Vesicomyinae (Bivalvia: Vesicomyidae) of the Kuril-Kamchatka Trench and adjacent abyssal regions

    Science.gov (United States)

    Krylova, Elena M.; Kamenev, Gennady M.; Vladychenskaya, Irina P.; Petrov, Nikolai B.

    2015-01-01

    Representatives of the subfamily Vesicomyinae (Bivalvia, Vesicomyidae) are tiny deep-sea molluscs distributed worldwide and reaching huge abundances of hundreds and thousands of specimens in trawl catches. During the German-Russian deep-sea expedition KuramBio (R/V Sonne, 2012) for the first time two vesicomyin species were collected from the abyssal plain adjacent to the Kuril-Kamchatka Trench from the depths of 4861-5787 m, Vesicomya pacifica (Smith, 1885) and "Vesicomya" filatovae sp.n. Two species of vesicomyins, V. sergeeviFilatova, 1971 and V. profundiFilatova, 1971, which were previously reported from the hadal of the Kuril-Kamchatka Trench, were not collected at the abyssal depth despite of the close geographical proximity of the sampling area to their distribution ranges. Altogether nine species of vesicomyins are recorded now from the West and Indo-West Pacific; data on distribution and morpho-anatomical characters of these species are provided. Taxonomic description of V. pacifica is revised including information on its soft part anatomy, new localities and COI sequences. For the first time for a vesicomyin bivalve molecular data is given for a species with an explicit morphological description and unambiguous taxonomic affiliation. Molecular analysis of 160 published COI sequences of vesicomyids and newly obtained molecular data on V. pacifica showed that V. pacifica and two undescribed vesicomyin species forming a monophyletic clade which exhibits sister relationships with the Pliocardiinae, the group of chemosymbiotic vesicomyids. "Vesicomya" filatovae sp.n. is provisionally assigned to the genus Vesicomya (s.l.) until additional morphological and molecular data are obtained. It differs from Vesicomya s.s. by a broader hinge margin with more radiating teeth and the presence of only one pair of demibranchs.

  16. Source-To-Sink Perspectives On The Mississippi River System, Miocene To Present, Mountain To Abyss

    Science.gov (United States)

    Bentley, S. J.; Blum, M. D.

    2013-12-01

    . The objective of this study is to present a synthesis of the Mississippi River source-to-sink system, from montane source to abyssal sink, to elucidate specific geomorphic components and boundaries in the system, controls on mass transfer, and resultant geomorphic and statigraphic development. The Mississippi River source-to-sink system constitutes one of the largest sources, conduits, and depocenters of sediment on Earth, extending from elevations of 3.7 km in the Rocky Mountains to the Gulf of Mexico abyssal plain. Despite being one of the most intensely studied fluvial-marine systems in the world, comprehensive understanding and management of the system's resources remain a challenge. The system is valuable in many ways: it provides navigation and water to the heart of North America, and sustains extensive marine fisheries. The river has built a delta that is home to millions of people and yet is subsiding rapidly. Ancestral Mississippi fluvial-marine deposits continue to yield high-value petroleum resources to exploration. To address the range of temporal and spatial scales over which the system has developed and continues to evolve, we will focus on three geological time spans that display contrasting geologic forcing and response: Miocene, Pleistocene, and late Holocene. The present configuration of source, conduit, and sink were established during the Miocene epoch, when tectonics (via the uplifting southern Rockies, and later the rejuvenated Appalachians) and climate (wet in the east and dry in the west) provided abundant water and sediment to prograde the shelf margin and initiate deep-sea fan growth. Pleistocene continental glaciation, eustasy, and catastrophic drainage events further sculpted the alluvial valley, and extended the shelf margin, and fan. Studies of Modern processes and Holocene delta development have provided keys to both the delta's past and future evolution, in terms of cyclic autogenic lobe-switching, mass-transport events, storm

  17. Endolithic Microbial Communities in Fractures: Insights Gleaned from Mineralized Filaments in Cretaceous-age Calcite Veins in Serpentinized Peridotites, Iberia Abyssal Plain

    Science.gov (United States)

    Milliken, K. L.

    2001-03-01

    The occurrence of diverse mineralized microbial features in calcitized fractures in serpentinized peridotite, Iberia Abyssal Plain, suggests that mineralized fractures are of particular interest in the search for fossil or extant life on Mars.

  18. On rank 4 projective planes

    OpenAIRE

    Bachmann, O.

    1981-01-01

    Let a finite projective plane be called rank m plane if it admits a collineation group G of rank m, let it be called strong rank m plane if moreover GP=G1 for some point-line pair (P,1). It is well known that every rank 2 plane is desarguesian (Theorem of Ostrom and Wagner). It is conjectured that the only rank 3 plane is the plane of order 2. By [1] and [7] the only strong rank 3 plane is the plane of order 2. In this paper it is proved that no strong rank 4 plane exists.

  19. Uppermost Jurassic to Lower Cretaceous benthic foraminiferal biostratigraphy at ODP Site 765 on the Argo Abyssal Plain.

    OpenAIRE

    Kaminski, M.A.; Gradstein, F.M.; Geroch, S.

    1992-01-01

    Benthic foraminifers were studied in 99 samples collected from the lower 200 m of Hole 765C. The studied section ranges from the Tithonian to Aptian, and benthic foraminifers can be subdivided into five assemblages on the basis of faunal diversity and stratigraphic ranges of distinctive species. Compared with deep-water assemblages from Atlantic DSDP sites and Poland, assemblages from the Argo Abyssal Plain display a higher diversity of agglutinated forms, which comprise the autochthonous ...

  20. Morphological, histochemical and immunohistochemical study of the gill epithelium in the abyssal teleost fish Coelorhynchus coelorhynchus

    OpenAIRE

    Aurelio Licata; Silvestro Martella; Eugenia Rita Lauriano; Maria Pia Albanese; Concetta Calabrò

    2011-01-01

    Histochemical and immunohistochemical study was carried out on nitrinergic innervation and neuroendocrine system in the gill epithelium of the abyssal fish Coelorhynchus coelorhynchus. The results showed that nNOS-positive nerve fibers, originating from the branchial arch were present in the subepithelial tissue of branchial primary filament. nNOS-positive neuroendocrine cells were also present in the primary filaments and secondary lamellae. Numerous mucous cells in the gi...

  1. On A Simple Parameterization and Global Extrapolation of Topography-Catalyzed Diapycnal Mixing in the Abyssal Ocean

    Science.gov (United States)

    Decloedt, T.; Luther, D. S.

    2006-12-01

    The potential role of topography-catalyzed mixing in maintaining the observed abyssal stratification is re- examined in light of the growing body of fine- and micro-structure data revealing energetic mixing near rough topography. A large collection of these fine- and micro-structure data sets from various oceanic regions are employed to develop a simple parameterization of the mean vertical structure of diapycnal mixing. The parameterization depends only on seafloor roughness and a power law function of height above bottom. Resulting global diffusivity maps show considerable spatial variability and suggest the need for more exploration of regions where non-tidal energy sources may generate near-boundary mixing. Basin-average diffusivity profiles and total dissipation rate estimates are found to be sensitive to the strength of mixing very close to the boundary (within 200 m). The contention that topography-catalyzed mixing is an important factor in maintaining the abyssal stratification is supported. Near-boundary mixing is perhaps the dominant factor below 3 km of depth, and is a significant factor at depths as shallow as one kilometer where it may provide as much as 1/3 of the bulk diffusivity required to maintain the stratification (under the assumption that diapycnal mixing is the sole mechanism for maintaining the stratification). The power required by the model to sustain this basin-average diffusivity profile in the abyssal oceans (1-4 km depth, 40 S to 48 N) is 0.41 TW to 0.89 TW (depending on the maximum near-boundary diffusivity prescribed in the power law model), in contrast to about 0.65 TW to maintain a diffusivity of 1 Stoke in the abyssal oceans.

  2. Links between surface productivity and deep ocean particle flux at the Porcupine Abyssal Plain (PAP) sustained observatory

    OpenAIRE

    Frigstad, H.; Henson, S. A.; Hartman, S. E.; A. M. Omar; E. Jeansson; Cole, H.; Pebody, C.; Lampitt, R. S.

    2015-01-01

    In this study we present hydrography, biogeochemistry and sediment trap observations between 2003 and 2012 at Porcupine Abyssal Plain (PAP) sustained observatory in the northeast Atlantic. The time series is valuable as it allows for investigation of the link between surface productivity and deep ocean carbon flux. The region is a perennial sink for CO2, with an average uptake of around 1.5 mmol m−2 d−1. The average monthly drawdowns of inorganic carbon and ...

  3. Morphological, histochemical and immunohistochemical study of the gill epithelium in the abyssal teleost fish Coelorhynchus coelorhynchus

    Directory of Open Access Journals (Sweden)

    Aurelio Licata

    2011-08-01

    Full Text Available Histochemical and immunohistochemical study was carried out on nitrinergic innervation and neuroendocrine system in the gill epithelium of the abyssal fish Coelorhynchus coelorhynchus. The results showed that nNOS-positive nerve fibers, originating from the branchial arch were present in the subepithelial tissue of branchial primary filament. nNOS-positive neuroendocrine cells were also present in the primary filaments and secondary lamellae. Numerous mucous cells in the gill epithelium were AB/PAS-positive, while sialic acid was absent as confirmed by neuraminidase reaction and WGA lectin histochemistry. The mucus compounds in abyssal teleost fish are different from those found in pelagic species, being related to their living conditions. In abyssal species, greater numbers of chloride and neuroendocrine cells are involved in the movement of water and electrolytes. Neuroendocrine cells possess oxygen receptors which mediate the cardiovascular and ventilatory response to oxygen deficiency, as reported in teleost species. Besides, NO contributes through nervous stimulation to the regulation of vascular tone and blood circulation in the gill.

  4. Abyssal θ-S Observations at Hawaii Ocean Time-series Station ALOHA

    Science.gov (United States)

    Lukas, R.; Santiago-Mandujano, F.; Fumar, C.; McCoy, D.; Deppe, R. W.; Gum, J.; Snyder, J.; Chee, B.; Howe, B. M.; Potemra, J. T.; Duennebier, F. K.

    2014-12-01

    Abyssal θ-S variations observed since June 2011 by the ALOHA Cabled Observatory (ACO) reveal a potential temperature range of 0.025°C, and a salinity range of more than 0.0025 g kg-1. The very large temperature range is associated with episodic cold events (Lukas et al.2001; Alford et al. 2011). The salinity range, while not large in absolute terms, is an order of magnitude larger than the precision of the Sea-Bird Microcat. The absolute salinity is calibrated against simultaneous Hawaii Ocean Time-series (HOT) full-depth CTD profiles that have an accuracy of ~10-3 g kg-1. A slow drift of the SBE-37 conductivity sensor is seen, along with a sudden offset that may have been caused by a nearby glass ball implosion. θ-S variations are dominated by changes in density that are associated with dynamic processes. Large cooling events are associated with increases of salinity ultimately deriving from the neighboring Maui Deep. The slopes of these excursions in θ-S space are consistent with the slopes of HOT CTD depth profiles, suggesting that these are vertical changes due either to gravity currents associated with cold, salty overflow events from the Maui Deep, or to internal seiches within the Kauai Deep. θ-S variations that are nearly isopycnal are also seen during the slow recovery from a major cooling event in 2011. This may be due to diapycnal mixing with fresher waters above the controlling sill depth. It cannot be ruled out that some apparent salinity changes may be associated with sediment resuspension events, with subsequent deviations from the PSS-78 empirical relationship between conductivity, salinity, temperature and pressure. ADCP records show large vacillations of along- and cross-isobath flow. Large vertical current variations are measured that are correlated with horizontal flows, likely due to the bottom slope, even after minimizing correlations to account for the unknown orientation of the ADCP. The primary conclusion is that abyssal dynamics

  5. Diversity and distribution of Porifera in the bathyal and abyssal Weddell Sea and adjacent areas

    Science.gov (United States)

    Janussen, Dorte; Tendal, Ole Secher

    2007-08-01

    During the ANDEEP I-III expeditions, we obtained a rich and highly diverse sponge collection from the deep Weddell Sea. All the three Poriferan classes, Calcarea, Demospongiae and Hexactinellida, were well represented. Among this material, we have identified a total of 76 species from 47 genera and 30 families. Of these, 17 species (22%) are new to science and 37 (49%) new for the Southern Ocean. Particularly remarkable is the considerable depth of the boundary between bathyal and abyssal sponge faunas. Both Demospongiae and Hexactinellida show a strong shift in their taxonomic composition from a typical shelf assemblage to a more cosmopolitan deep-sea fauna at around 2500 m. Within the Demospongiae, the families Polymastiidae and Cladorhizidae (carnivorous sponges) are particularly abundant and very diverse. The Calcarea are recorded for the first time from the Antarctic deep sea. The type of sampling gear used, especially the epibenthic sledge, was an important factor for the successful collection of deep-sea sponges during the ANDEEP campaigns.

  6. Mineralogy of the mid-ocean-ridge basalt source from neodymium isotopic composition of abyssal peridotites.

    Science.gov (United States)

    Salters, Vincent J M; Dick, Henry J B

    2002-07-01

    Inferring the melting process at mid-ocean ridges, and the physical conditions under which melting takes place, usually relies on the assumption of compositional similarity between all mid-ocean-ridge basalt sources. Models of mantle melting therefore tend to be restricted to those that consider the presence of only one lithology in the mantle, peridotite. Evidence from xenoliths and peridotite massifs show that after peridotite, pyroxenite and eclogite are the most abundant rock types in the mantle. But at mid-ocean ridges, where most of the melting takes place, and in ophiolites, pyroxenite is rarely found. Here we present neodymium isotopic compositions of abyssal peridotites to investigate whether peridotite can indeed be the sole source for mid-ocean-ridge basalts. By comparing the isotopic compositions of basalts and peridotites at two segments of the southwest Indian ridge, we show that a component other than peridotite is required to explain the low end of the (143)Nd/(144)Nd variations of the basalts. This component is likely to have a lower melting temperature than peridotite, such as pyroxenite or eclogite, which could explain why it is not observed at mid-ocean ridges. PMID:12097907

  7. Ocean abyssal carbon experiments at 0.7 and 4 km depth

    International Nuclear Information System (INIS)

    Since 2002, researchers from Japan, the United States and Norway have been collaborating on the Ocean Abyssal Carbon Experiment (OACE) project. This paper presented information on the three year project. It presented a discussion of the high-pressure laboratory work, instrument development and theoretical and numerical modelling associated with field experiments. The purpose of the project is to conduct groundbreaking and challenging experiments to determine of the fate of carbon dioxide (CO2) disposed onto the ocean floor. Several observations from small-scale CO2 experiments at different depths conducted off the coast of California were presented. In the experiments, when the seawater velocity was sufficiently strong, parcels of liquid CO2 were torn off and transported away as discrete units by the turbulent water current. Newly formed frazil hydrate was observed at the interface, occasionally including sediment particles in the deep experiment. In addition, hydrate collected and created a floating consolidated solid consisting of ice in the downstream end of the trough, dissolving slowly from one day to the next. It was concluded that these observations have significant implications for understanding and modelling of larger scale anthropogenic CO2 disposal at the seafloor. 15 refs., 3 figs

  8. Geochemistry of the near surface sediments of the Nares Abyssal Plain

    International Nuclear Information System (INIS)

    The geochemistry of a suite of box and 2m gravity cores from the Nares Abyssal Plain has been characterised by means of pore water analyses, XRF determination of major and trace element concentrations, mineralogy and 230Thsub(excess) dating. The interstitial fluid environment of those deep-sea clays is mildly reducing, although one site exhibits manganese remobilisation and precipitation. Despite their marked colour differences, there is a similarity in clay mineralogy between the grey silt/clay turbidites and the brown clays found in the area. Sediment accumulation rates of pelagic brown clays range between 0.5 and 1.0 cm/103 yr. These pelagic brown clays are metal-rich relative to the grey clays, and a model is used to estimate the hydrogenous metal fluxes on the assumption that they are constant over the Plain. This model gives values of approx. 1300 μg/cm2/103 yr for Mn, approx. 2600 μg/cm2/103 yr for Fe and Co, Ni, Cu, V and Zn in the range 6 to 26 μg/cm2/103 yr. An associated model-derived estimate of the detrital contents of the same elements agrees well with the mean values of the grey clays and of average shale. Metal-poor brown clays and assorted minor lithologies are intermediate in composition between these two end-members. (author)

  9. Surprises in abyssal peridotites: implications for melt migration beneath ocean ridges

    Science.gov (United States)

    Niu, Y.

    2003-04-01

    Since Mike's two classic papers [1,2], the last 35 years have seen much progress on MORB petrogenesis because of improved experimental/theoretical approaches and because of rapid growth of geochemical database on MORB samples from the global ocean ridge system. Our current understanding of MORB genesis also owes a great deal to the studies [3-5] of abyssal peridotites - interpreted as mantle melting residues for MORB. Recent studies [6,7] have confirmed the complementary relationship between MORB and abyssal peridotites, but also revealed the hidden complexities in these peridotites such as olivine addition [6-8] and melt refertilization [7-9]. These same studies [6,7] have simultaneously excited serious debates on the petrogenesis of abyssal peridotites [10-14]. These debates are actually different views on the same observations: modes and major element compositions of residual minerals, and trace element data on residual clinopyroxene (Cpx) [3-5]. I report here whole-rock ICP-MS trace element data on abyssal peridotites including samples previously studied for Cpx trace elements [5]. Residual Cpx shows highly depleted light rare earth elements (LREEs) with flat-to-elevated middle-heavy REEs (e.g., [Ce]_N = 0.25±0.51 [mean±1σ]; [Yb]_N = 6.09±2.59; [Nd/Sm]_N = 0.29±0.14; [Nd/Dy]_N = 0.14±0.11), which is consistent with varying extents of melt depletion [5]. In contrast, whole-rock data of the same samples [15] show elevated abundances of LREEs with flat to enriched LREE patterns (e.g., [Ce]_N = 0.57±0.74; [Yb]_N, 0.72±0.41; [Nd/Sm]_N = 1.18±0.41; [Nd/Dy]_N = 0.70±0.38). If the constituent Cpx records the melting process, the whole-rock data would suggest post-melting LREE addition. The significant correlations of LREEs with high-field strength elements (HFSEs) (e.g., RCe-Zr = 0.730, RNd-Zr = 0.789, RCe-Nb = 0.836, RNd-Nb = 0.900) suggest that this LREE addition is magmatic refertilization (vs. serpentinization). The observation that this magmatic

  10. BKP plane partitions

    Energy Technology Data Exchange (ETDEWEB)

    Foda, Omar; Wheeler, Michael [Department of Mathematics and Statistics, University of Melbourne, Parkville, Victoria 3010 (Australia)

    2007-01-15

    Using BKP neutral fermions, we derive a product expression for the generating function of volume-weighted plane partitions that satisfy two conditions. If we call a set of adjacent equal height-h columns, h > 0, an h-path, then 1. Every h-path can assume one of two possible colours. 2. There is a unique way to move along an h-path from any column to another.

  11. BKP plane partitions

    OpenAIRE

    Foda, O.; Wheeler, M.

    2006-01-01

    Using BKP neutral fermions, we derive a product expression for the generating function of volume-weighted plane partitions that satisfy two conditions. If we call a set of adjacent equal height-h columns, h > 0, an h-path, then 1. Every h-path can assume one of two possible colours. 2. There is a unique way to move along an h-path from any column to another.

  12. BKP plane partitions

    International Nuclear Information System (INIS)

    Using BKP neutral fermions, we derive a product expression for the generating function of volume-weighted plane partitions that satisfy two conditions. If we call a set of adjacent equal height-h columns, h > 0, an h-path, then 1. Every h-path can assume one of two possible colours. 2. There is a unique way to move along an h-path from any column to another

  13. Homogeneous Plane Waves

    OpenAIRE

    Blau, Matthias; O'Loughlin, Martin

    2002-01-01

    Motivated by the search for potentially exactly solvable time-dependent string backgrounds, we determine all homogeneous plane wave (HPW) metrics in any dimension and find one family of HPWs with geodesically complete metrics and another with metrics containing null singularities. The former generalises both the Cahen-Wallach (constant $A_{ij}$) metrics to time-dependent HPWs, $A_{ij}(t)$, and the Ozsvath-Sch\\"ucking anti-Mach metric to arbitrary dimensions. The latter is a generalisation of ...

  14. Boundaries in digital planes

    Directory of Open Access Journals (Sweden)

    Efim Khalimsky

    1990-01-01

    Full Text Available The importance of topological connectedness properties in processing digital pictures is well known. A natural way to begin a theory for this is to give a definition of connectedness for subsets of a digital plane which allows one to prove a Jordan curve theorem. The generally accepted approach to this has been a non-topological Jordan curve theorem which requires two different definitions, 4-connectedness, and 8-connectedness, one for the curve and the other for its complement.

  15. Organic carbon cycling in abyssal benthic food chains: numerical simulations of bioenhancement by sewage sludge

    Science.gov (United States)

    Rowe, Gilbert T.

    1998-05-01

    The hypothetical bioenhancement of the endemic benthic biota on an oligotrophic abyssal plain by organic carbon has been investigated with mathematical simulation experiments. First, the responses of the biomass and respiration to seasonal variations in the rain of organic carbon (POC) have been simulated in a simplified benthic assemblage (sediment organic carbon, sediment-dwelling heterotrophs (bacteria, meiofauna, macrofauna and detritus feeding megafauna) and predatory megafauna), with no added organic matter. These calculations were based on measured standing stocks and respiration in the central North Pacific (5.8 km depth, 31°N Lat.×159°W Long.). The dynamic relationships in this natural "oligotrophic" food chain were then subjected to added inputs of organic carbon presumed to be in sewage sludge. Two examples are presented: a modest but continuous input of organic carbon (100 mg C m -2 d -1) and a year-long pulse of the same intensity. The continuous input forced the biomass and community respiration to steadily increase until they reached steady state in 15 years at values similar to those found on a typical continental shelf. The pulse exhibited the same pattern, but biomass and respiration returned to levels found under natural oligotrophic conditions several years after cessation of intensified carbon loading. The responses of the sediment community to added organic matter were validated using information from a deep-ocean sewage disposal site (DWD106) off the coast of New Jersey. The models are also used to illustrate an approach for estimating possible transfers of potentially toxic contaminants, such as total polycyclic aromatic hydrocarbons (tPAHs), in lipid-rich eggs. In the future it will be necessary to validate model results with deep-ocean in situ experiments.

  16. Moored observation of abyssal flow and temperature near a hydrothermal vent on the Southwest Indian Ridge

    Science.gov (United States)

    Liao, Guanghong; Zhou, Beifeng; Liang, Chujin; Zhou, Huaiyang; Ding, Tao; Wang, Yuan; Dong, Changming

    2016-01-01

    Four moorings were deployed near "Dragon Flag," an active hydrothermal vent in the valley of the Southwest Indian Ridge. The goal was to examine the variability of currents and temperature, which will guide the trajectory of spreading plumes. The mean current was cross-isobath, and the circulation was characterized by a submesoscale circulation. Observed currents also showed fluctuations with periods of 1-15 days. The inferred phase speed and wavelength for the wave with a period of 4.4 day are 10.4 km d-1 and 45.8km, respectively, which are consistent with the topographic Rossby wave theory. The persistent warming tendency with corresponding variation of salinity based on background θ-S properties may be caused by background circulation and divergence of the water column. The warming or cooling episodes were most likely as signatures of isopycnal surface depression or uplifting induced by the moving of mesoscale eddies. Well-resolved rotary spectra exhibited important nonlinear interactions between inertial and semidiurnal tide in the velocity and temperature records. Amplification of near-inertial currents in the near bottom is also exposed. These discoveries provided new evidence for the nonlinear interaction and trapped near-inertial waves by the ridge, which occurred in the deep ocean of the Southern Hemisphere. Such nonlinear interaction may represent a significant energy loss pathway for the internal waves, and part of the decay of such motion would likely result in increased mixing to maintain the abyssal stratification. Enhanced near-inertial motions can play a major role for the local advection of hydrothermal plumes.

  17. Pore water geochemistry and the oxidation of sedimentary organic matter: Hatteras Abyssal Plain 1981

    International Nuclear Information System (INIS)

    This report presents the pore water geochemistry from R/V an Endeavor cruise to an area of the Hatteras Abyssal Plain between 310 45' - 340 00'N and 690 37.5 - 720 07.5'W. The authors report on the down core variations of the products of organic matter oxidation, the stoichiometry of reactions and make a preliminary assessment of the rates of organic matter oxidation at several core locations. The authors found concentrations of total inorganic nitrogen species; nitrate, nitrite and ammonia in pore waters to be less than those predicted from a model of organic matter oxidation (Froelich et al. 1979) in sediments. The observations indicate that nitrogen is depleted over carbon as compared to typical marine organic matter. The down-core nitrate profiles over the study area were used to infer depths at which oxygen is near totally consumed in the sediments and hence to compute rates of oxygen consumption. The authors found oxygen consumption rates to vary by nearly an order of magnitude between core locations (1.7 - >15μmO2 cm-2 yr-1). A simple model which combines the computed rates of oxidant consumption and the stoichiometry of organic matter oxidation was used to make estimates of organic carbon oxidation rates. These latter were found to vary between 1.3 and > 11.5 μm C cm-2 yr-1. Highest carbon oxidation rates were found at the western boundary of the study area, and in all cases oxygen consumption was responsible for >85% of carbon oxidized. 11 references, 5 figures, 4 tables

  18. Links between surface productivity and deep ocean particle flux at the Porcupine Abyssal Plain sustained observatory

    Science.gov (United States)

    Frigstad, H.; Henson, S. A.; Hartman, S. E.; Omar, A. M.; Jeansson, E.; Cole, H.; Pebody, C.; Lampitt, R. S.

    2015-10-01

    In this study we present hydrography, biogeochemistry and sediment trap observations between 2003 and 2012 at Porcupine Abyssal Plain (PAP) sustained observatory in the Northeast Atlantic. The time series is valuable as it allows for investigation of the link between surface productivity and deep ocean carbon flux. The region is a perennial sink for CO2, with an average uptake of around 1.5 mmol m-2 day-1. The average monthly drawdowns of inorganic carbon and nitrogen were used to quantify the net community production (NCP) and new production. Seasonal NCP and new production were found to be 4.57 ± 0.85 mol C m-2 and 0.37 ± 0.14 mol N m-2, respectively. The C : N ratio was high (12) compared to the Redfield ratio (6.6), and the production calculated from carbon was higher than production calculated from nitrogen, which is indicative of carbon overconsumption. The export ratio and transfer efficiency were 16 and 4 %, respectively, and the site thereby showed high flux attenuation. Particle tracking was used to examine the source region of material in the sediment trap, and there was large variation in source regions, both between and within years. There were higher correlations between surface productivity and export flux when using the particle-tracking approach, than by comparing with the mean productivity in a 100 km box around the PAP site. However, the differences in correlation coefficients were not significant, and a longer time series is needed to draw conclusions on applying particle tracking in sediment trap analyses.

  19. Inter-annual species-level variations in an abyssal polychaete assemblage (Sta. M, NE Pacific, 4000 m)

    Science.gov (United States)

    Laguionie-Marchais, Claire; Paterson, Gordon L. J.; Bett, Brian J.; Smith, Kenneth L.; Ruhl, Henry A.

    2016-01-01

    Understanding the dynamics of abyssal community structure and function has become increasingly important as deep-sea resource exploitation and climate change pressures are expected to ramp up. This time-series study investigates macrofaunal polychaete dynamics at a station in the North East Pacific (Sta. M; 35° N 123° W, 4000 m, 1991-2011). Infaunal polychaete species were identified and their proxy biomass and proxy energy use rate estimated. The assemblage comprised 167 species, having a composition consistent with other abyssal areas globally. Significant changes in univariate and multivariate parameters (rank abundance distribution, Simpson's diversity index, and species and functional group composition) were detected across 1991-2011. However, no change in biomass or energy use rate was apparent through the time-series. The largest changes in the polychaete assemblage coincided with both an increase in sinking particulate organic carbon flux to the seafloor in 2007, and a 40 km relocation of the sampling location to a site 100 m shallower, preventing a conclusive assessment of which might drive the observed variation. Analyses prior to the change of sampling location showed that the polychaete assemblage composition dynamics were primary driven by food supply variation. Changes in several species were also lagged to changes in POC flux by 4-10 months. The polychaete fauna exhibited a significant positive relationship between total density and total energy use rate, suggesting population-level tracking of a common resource (e.g. POC flux food supply). Neither compensatory nor energetic zero-sum dynamics were detected among the polychaete assemblage, but the results suggest that the latter occur in the macrofaunal community as a whole. The results do indicate (a) potential control of species composition, and the density of individual key species, by food supply, when the time-series prior to the sampling location was analysed separately, and (b) generally

  20. Great Meteor East (distal Madeira Abyssal Plain): geological studies of its suitability for disposal of heat-emitting radioactive wastes

    International Nuclear Information System (INIS)

    This report summarises geological and geophysical studies carried out by the Institute of Oceanographic Sciences up to December 1983 in an area of the Madeira Abyssal Plain in order to assess its suitability for the disposal of heat-emitting radioactive waste. The results of work carried out in the same area by the Rijks Geologische Dienst of the Netherlands are also reviewed in the report. Other oceanographic studies in the area in the fields of geochemistry, biology and oceanography are briefly touched upon. (author)

  1. Plane and geodetic surveying

    CERN Document Server

    Johnson, Aylmer

    2004-01-01

    Plane and Geodetic Surveying blends theory and practice, conventional techniques and GPS, to provide the ideal book for students of surveying.Detailed guidance is given on how and when the principle surveying instruments (theodolites, Total Stations, levels and GPS) should be used. Concepts and formulae needed to convert instrument readings into useful results are explained. Rigorous explanations of the theoretical aspects of surveying are given, while at the same time a wealth of useful advice about conducting a survey in practice is provided. An accompanying least squares adjustment program

  2. Homogeneous plane waves

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Matthias E-mail: mblau@ictp.trieste.it; O' Loughlin, Martin E-mail: loughlin@sissa.it

    2003-03-24

    Motivated by the search for potentially exactly solvable time-dependent string backgrounds, we determine all homogeneous plane wave (HPW) metrics in any dimension and find one family of HPWs with geodesically complete metrics and another with metrics containing null singularities. The former generalises both the Cahen-Wallach (constant A{sub ij}) metrics to time-dependent HPWs, A{sub ij}(x{sup +}), and the Ozsvath-Schuecking anti-Mach metric to arbitrary dimensions. The latter is a generalisation of the known homogeneous metrics with A{sub ij}{approx}1/(x{sup +}){sup 2} to a more complicated time-dependence. We display these metrics in various coordinate systems, show how to embed them into string theory, and determine the isometry algebra of a general HPW and the associated conserved charges. We review the Lewis-Riesenfeld theory of invariants of time-dependent harmonic oscillators and show how it can be deduced from the geometry of plane waves. We advocate the use of the invariant associated with the extra (timelike) isometry of HPWs for lightcone quantisation, and illustrate the procedure in some examples.

  3. The MOND Fundamental Plane

    CERN Document Server

    Cardone, V F; Diaferio, A; Tortora, C; Molinaro, R

    2010-01-01

    Modified Newtonian Dynamics (MOND) has been shown to be able to fit spiral galaxy rotation curves as well as giving a theoretical foundation for empirically determined scaling relations, such as the Tully - Fisher law, without the need for a dark matter halo. As a complementary analysis, one should investigate whether MOND can also reproduce the dynamics of early - type galaxies (ETGs) without dark matter. As a first step, we here show that MOND can indeed fit the observed central velocity dispersion $\\sigma_0$ of a large sample of ETGs assuming a simple MOND interpolating functions and constant anisotropy. We also show that, under some assumptions on the luminosity dependence of the Sersic n parameter and the stellar M/L ratio, MOND predicts a fundamental plane for ETGs : a log - linear relation among the effective radius $R_{eff}$, $\\sigma_0$ and the mean effective intensity $\\langle I_e \\rangle$. However, we predict a tilt between the observed and the MOND fundamental planes.

  4. Homogeneous plane waves

    International Nuclear Information System (INIS)

    Motivated by the search for potentially exactly solvable time-dependent string backgrounds, we determine all homogeneous plane wave (HPW) metrics in any dimension and find one family of HPWs with geodesically complete metrics and another with metrics containing null singularities. The former generalises both the Cahen-Wallach (constant Aij) metrics to time-dependent HPWs, Aij(x+), and the Ozsvath-Schuecking anti-Mach metric to arbitrary dimensions. The latter is a generalisation of the known homogeneous metrics with Aij∼1/(x+)2 to a more complicated time-dependence. We display these metrics in various coordinate systems, show how to embed them into string theory, and determine the isometry algebra of a general HPW and the associated conserved charges. We review the Lewis-Riesenfeld theory of invariants of time-dependent harmonic oscillators and show how it can be deduced from the geometry of plane waves. We advocate the use of the invariant associated with the extra (timelike) isometry of HPWs for lightcone quantisation, and illustrate the procedure in some examples

  5. Homogeneous Plane Waves

    CERN Document Server

    Blau, Matthias; Blau, Matthias; Loughlin, Martin O'

    2003-01-01

    Motivated by the search for potentially exactly solvable time-dependent string backgrounds, we determine all homogeneous plane wave (HPW) metrics in any dimension and find one family of HPWs with geodesically complete metrics and another with metrics with null singularities. The former generalises both the Cahen-Wallach (constant $A_{ij}$) metrics to time-dependent HPWs, $A_{ij}(t)$, and the Ozsvath-Sch\\"ucking anti-Mach metric to arbitrary dimensions. The latter is a generalisation of the known homogeneous metrics with $A_{ij}\\sim 1/t^2$ to a more complicated time-dependence. We display these metrics in various coordinate systems, show how to embed them into string theory, and determine the isometry algebra of a general HPW and the associated conserved charges. We review the Lewis-Riesenfeld theory of invariants of time-dependent harmonic oscillators and show how it can be deduced from the geometry of plane waves. We advocate the use of the invariant associated with the extra (timelike) isometry of HPWs for ...

  6. Composition and distribution of bivalves of the abyssal plain adjacent to the Kuril-Kamchatka Trench (Pacific Ocean)

    Science.gov (United States)

    Kamenev, Gennady M.

    2015-01-01

    The KuramBio German-Russian deep-sea expedition ("Sonne", 2012) revealed a rich fauna of bivalves (55 species belonging to 21 families) on the abyssal plain (4861-5787 m) adjacent to the Kuril-Kamchatka Trench. Per station species richness varied from 18 to 33 species. The richest families were Cuspidariidae (7 species), Tindariidae (6 species), Thyasiridae (6 species), and Xylophagidae (5 species). The families Nuculidae, Malletidae, Yoldiidae, Mytilidae, Protocuspidariidae, and Verticordiidae were represented by a single species. Representatives of the family Siliculidae were recorded in the northwestern Pacific for the first time. Thirteen species (23.6%) were most common in the investigated northwestern Pacific region. Nine species (16.4%) were only found at one of the stations. Eight species (14.5%) are first records for the northwestern Pacific, of which Yoldiella cf. jeffreysi (Hidalgo, 1877), Pristigloma cf. albaSanders and Allen, 1973, and Syssitomya cf. pourtalesianaOliver, 2012 were previously known only for the Atlantic Ocean. The high diversity and richness of the bivalve fauna on the abyssal plain in the Kuril-Kamchatka Trench area may be connected to the favorable feeding conditions in this, one of the most highly productive areas of the Pacific Ocean.

  7. Morphological and ontogenetic stratification of abyssal and hadal Eurythenes gryllus sensu lato (Amphipoda: Lysianassoidea) from the Peru-Chile Trench

    Science.gov (United States)

    Eustace, Ryan M.; Ritchie, Heather; Kilgallen, Niamh M.; Piertney, Stuart B.; Jamieson, Alan J.

    2016-03-01

    The globally ubiquitous lysianassoid amphipod, Eurythenes gryllus, has been shown to consist of multiple genetically distinct cryptic taxa, with depth considered a major driver of speciation and morphological divergence. Here we examine morphological variation of E. gryllus sensu lato through a continuous depth distribution that spans from abyssal (3000-6000 m) into hadal depths (>6000 m) in the Peru-Chile Trench (SE Pacific Ocean). Three distinct morphospecies were identified: one was confirmed as being E. magellanicus (4602-5329 m) based on DNA sequence and morphological similarity. The other two morphologically distinct species were named based upon depth of occurrence; Abyssal (4602-6173 m) and Hadal (6173-8074 m). The three Eurythenes morphospecies showed vertical ontogenetic stratification across their bathymetric range, where juveniles were found shallower in their depth range and mature females deeper. Potential ecological and evolutionary drivers that explain the observed patterns of intra and inter-specific structure, such as hydrostatic pressure and topographical isolation, are discussed.

  8. Temporal and depth-related differences in prokaryotic communities in abyssal sediments associated with particulate organic carbon flux

    Science.gov (United States)

    Moeseneder, M. M.; Smith, K. L.; Ruhl, H. A.; Jones, D. O. B.; Witte, U.; Prosser, J. I.

    2012-12-01

    Particulate organic carbon (POC) flux is hypothesized to be the most important parameter influencing activity and biomass of prokaryotic and faunal communities in the abyssal seafloor, but there is little evidence of POC-related changes in community composition of prokaryotes. This hypothesis was tested by 16S rRNA-gene-based analysis of prokaryotic DNA and RNA extracted from abyssal seafloor sediments during periods of low and high POC flux. Fingerprint analysis of prokaryotic communities indicated that approximately 50% of the phylotypes were identical at each sediment horizon, regardless of the temporal variations in POC flux. However, phylotypes were also detected that represented a relatively dynamic component of these communities and were probably strongly influenced by the prevalent POC flux regime. These patterns were also detected in deeper sediment horizons. DNA- and RNA-based community profiles differed, although both approaches had similar community dynamics. Crenarchaeota showed the strongest shift in community composition in response to availability of labile POC, indicating that POC flux may have a more pronounced impact on crenarchaeal communities than on bacterial communities. The high number of phylotypes common to each sample time suggests that both standing stock and active prokaryotic communities are stable.

  9. Duality and noncommutative planes

    DEFF Research Database (Denmark)

    Jøndrup, Søren

    2015-01-01

    We study extensions of simple modules over an associative ring A   and we prove that for twosided ideals mm and nn with artinian factors the condition ExtA1(A/m,A/n)≠0 holds for the left A  -modules A/mA/m and A/nA/n if and only if it holds for the right modules A/nA/n and A/mA/m. The methods pro...... proving this are applied to show that noncommutative models of the plane, i.e. algebras of the form k〈x,y〉/(f)k〈x,y〉/(f), where f∈([x,y])f∈([x,y]) are noetherian only in case (f)=([x,y])...

  10. "First" abyssal record of Stenosemus exaratus (G.O. Sars, 1878) (Mollusca, Polyplacophora) in the North-Atlantic Ocean.

    Science.gov (United States)

    Allcock, Louise; Schwabe, Enrico

    2013-01-01

    The first proven abyssal record of Stenosemus exaratus (G.O. Sars, 1878) is presented on the basis of an ROV study in the Irish Sea. For the first time in situ images of the species and data on the environmental parameters are provided. PMID:23794838

  11. “First” abyssal record of Stenosemus exaratus (G.O. Sars, 1878) (Mollusca, Polyplacophora) in the North-Atlantic Ocean

    Science.gov (United States)

    Allcock, Louise; Schwabe, Enrico

    2013-01-01

    Abstract The first proven abyssal record of Stenosemus exaratus (G.O. Sars, 1878) is presented on the basis of an ROV study in the Irish Sea. For the first time in situ images of the species and data on the environmental parameters are provided. PMID:23794838

  12. “First” abyssal record of Stenosemus exaratus (G.O. Sars, 1878 (Mollusca, Polyplacophora in the North-Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Louise Allcock

    2013-04-01

    Full Text Available The first proven abyssal record of Stenosemus exaratus (G.O. Sars, 1878 is presented on the basis of an ROV study in the Irish Sea. For the first time in situ images of the species and data on the environmental parameters are provided.

  13. Abyssal macrofauna of the Kuril-Kamchatka Trench area (Northwest Pacific) collected by means of a camera-epibenthic sledge

    Science.gov (United States)

    Brandt, A.; Elsner, N. O.; Malyutina, M. V.; Brenke, N.; Golovan, O. A.; Lavrenteva, A. V.; Riehl, T.

    2015-01-01

    Abyssal macrofaunal composition of 21 epibenthic sledge hauls from twelve stations taken in the Kuril-Kamchatka Trench (KKT) and at the adjacent abyssal plain, Northwest Pacific, is presented. Sampling with the fine meshed epibenthic sledge yielded higher abundances and species richness than was reported from previous expeditions from board of RV Vityaz. In total 84,651 invertebrates were sampled with RV Sonne between July and September of 2012 (31,854 invertebrates if standardised for 1000 m2 trawled distances) from 41 taxa of different taxonomic ranks (15 phyla, 28 classes, 7 orders) were sampled from a trawled area of 53,708 m² and have been analyzed. Few taxa were frequent and most taxa were rare in the samples, twelve taxa occurred with more than 1% frequency. Of these, the Polychaeta were most abundant followed by the benthic Copepoda and Isopoda. Total numbers of individuals varied between stations and were highest with 4238 individuals at station 2-10 close to the KKT in 4865 m depth and lowest with 374 individuals at station 6-11 in 5305 m depth. At this station also the lowest number of taxa occurred (18 taxa) while the highest number occurred with 31 taxa at station 3-9 in 4991 m depth. Numbers of individuals decreased with increasing depth between 4830 and 5780 m. Crustaceans of the superorder Peracarida were one of the dominating taxa with four orders occurring frequently in most samples. In total, Isopoda were most important and occurred with 59% of all peracarid orders sampled, followed by Amphipoda with 21%, Tanaidacea with 11%, Cumacea with 9%, and Mysidacea with abyssal area differ in terms of taxon composition from each other. A cluster analysis (nMDS) performed for all sampled stations revealed no clear pattern of community similarity between stations or hauls. All hauls close to the trench (2-9 and 2-10 close to the eastern slope of the KKT; and 3-9 and 4-3 at the western slope) were most different to the other hauls. Hauls 8-9 and 8-12 as

  14. Plane Mercury librations

    Science.gov (United States)

    Barkin, Yu. V.; Ferrandiz, J. M.

    2009-04-01

    theory of Mercury librations in longitude by using three characteristics of Mercury rotation determined in the paper [3]. Two from these parameters are values of angle of librations in longitude and angular velocity in moment of passage of perihelion of Mercury orbit on 17 April 2002: (^g)0 = 0007 ± 0001, (^?•? )0 = (2.10± 0.06)•? ars/d. Third parameter determined in [3] is a dynamical coefficient: K = (B -A)•(4Cm ) = (5.08± 0.30) × 10-5. B > A are principal moment of inertia, corresponding to equatorial axes of inertia; Cm is a polar moment of inertia of the mantle of Mercury. 1 Analytical theory of plane Mercury librations. This theory describes forced and free librations of Mercury in longitude in the frame of plane problem about resonant librations of Mercury considered or as non-spherical rigid body, or as system of rigid non-spherical mantle and liquid ellipsoidal core. Saving the main terms for the perturbations of angle of librations ^g and angular velocity ^? in both mentioned cases we will have formulae [6]: ^g = K(E sin M + E sin2M + E sin 3M + E sin4M + E sin5M ) 1 2 3 4 5+K0 sin(E šKM- - φ) (A)

  15. Population sizes and growth pressure responses of intestinal microfloras of deep-sea fish retrieved from the abyssal zone.

    Science.gov (United States)

    Yano, Y; Nakayama, A; Yoshida, K

    1995-12-01

    The intestinal floras of seven deep-sea fish retrieved at depths of from 3,200 to 5,900 m were examined for population sizes and growth responses to pressure. Large populations of culturable bacteria, ranging from 1.1 x 10(sup6) to 3.6 x 10(sup8) cells per ml of contents, were detected when samples were incubated at conditions characteristic of those of the deep sea. Culturable cell counts at in situ pressures were greater than those at atmospheric pressure in all samples. Most of the strains isolated by the spread-plating method at atmospheric pressure later proved barophilic. Barophilic bacteria were the predominant inhabitants of the abyssal fish intestines. PMID:16535199

  16. Heat flow measurements in the vicinity of Great Meteor East, Madeira Abyssal Plain, during Darwin Cruise CD9B

    International Nuclear Information System (INIS)

    This report describes 37 new measurements of heat flow in the Madeira Abyssal Plain. These have comprised 22 values in the Great Meteor East Study Area and 15 measurements in the newly defined ''10 km Box'' to the southeast of this region. The aim of the project has been to examine in more detail than hitherto the thermal and fluid processes operating in the oceanic crust. For this purpose, a new thermistor string, with 1/2 m sensor spacing was used. Also, the heat flux data have been compared to the output from a finite element model for heat conduction. No non-linear sediment temperature profiles were discovered indicating that vertical advection of water through the sediment is absent or slow. The results of numerical modelling imply that the variability of measured heat flow cannot be explained entirely on the basis of basement topography. It is necessary to invoke either vertical basement intrusions of differing conductivity or basement hydrothermal circulation. (author)

  17. Examination of abyssal sea floor and near-bottom water mixing processes using Ra-226 and Rn-222

    International Nuclear Information System (INIS)

    Since Broecker's (1965) original work, extensive studies have been made on abyssal near-bottom water-mixing processes using the radioactive parent-daughter pair radium-226 (Ra) - radon-222 (Rn). One assumption critical to all of these studies is that sediments immediately under a given water column are the source of excess radon (=Rn concentration - Ra concentration) found in bottom waters. Since 1965 theoretical works of increasing complexity have tried to explain areal variations of excess radon and radium. However, Key et al. (1979b) have reported the only extensive measurements of radium and radon in bottom water and sediments at the same location. This dissertation is an expansion of that work both in theory and in scope. A diagenetic sediment model based on the work of Schink and Guinasso (1978), Cochran (1979), and Key et al. (1979b) was developed to model Ra-Rn in near-surface abyssal sediments. In order to maximize model application information, the degrees of freedom were minimized by measuring as many of the model parameters as possible. The most glaring discrepancy found was that measured near-surface total radium profiles could not be fit using plutonium-derived bioturbation rates. There is an implication that plutonium profiles modeled with currently accepted bioturbation models do not give a true indication of the real biologically induced mixing process. After adjusting for this problem in the source function, diagenetic theory explains near-surface radon-distributions adequately. Using both the adjusted diagenetic model and the empirical model developed by Key et al. (1979b), reasonable agreement was found between the sedimentary radon deficit and near-bottom water surplus. Inadequacy of present diagenetic theory makes any attempt to differentiate sedimentary radium sources academic

  18. Cyclic magnetite dissolution in Pleistocene sediments of the abyssal northwest Pacific Ocean: Evidence for glacial oxygen depletion and carbon trapping

    Science.gov (United States)

    Korff, Lucia; Dobeneck, Tilo; Frederichs, Thomas; Kasten, Sabine; Kuhn, Gerhard; Gersonde, Rainer; Diekmann, Bernhard

    2016-05-01

    The carbonate-free abyss of the North Pacific defies most paleoceanographic proxy methods and hence remains a "blank spot" in ocean and climate history. Paleomagnetic and rock magnetic, geochemical, and sedimentological methods were combined to date and analyze seven middle to late Pleistocene northwest Pacific sediment cores from water depths of 5100 to 5700 m. Besides largely coherent tephra layers, the most striking features of these records are nearly magnetite-free zones corresponding to glacial marine isotope stages (MISs) 22, 12, 10, 8, 6, and 2. Magnetite depletion is correlated with organic carbon and quartz content and anticorrelated with biogenic barite and opal content. Within interglacial sections and mid-Pleistocene transition glacial stages MIS 20, 18, 16, and 14, magnetite fractions of detrital, volcanic, and bacterial origin are all well preserved. Such alternating successions of magnetic iron mineral preservation and depletion are known from sapropel-marl cycles, which accumulated under periodically changing bottom water oxygen and redox conditions. In the open central northwest Pacific Ocean, the only conceivable mechanism to cause such abrupt change is a modified glacial bottom water circulation. During all major glaciations since MIS 12, oxygen-depleted Antarctic Bottom Water (AABW)-sourced bottom water seems to have crept into the abyssal northwest Pacific below ~5000 m depth, thereby changing redox conditions in the sediment, trapping and preserving dissolved and particulate organic matter and, in consequence, reducing and dissolving both, biogenic and detrital magnetite. At deglaciation, a downward progressing oxidation front apparently remineralized and released these sedimentary carbon reservoirs without replenishing the magnetite losses.

  19. Gravitational Couplings for Gop-Planes and y-Op-Planes

    CERN Document Server

    Ospina-Giraldo, J F

    2000-01-01

    The Wess-Zumino actions for generalized orientifold planes (GOp-planes) and y-deformed orientifold planes (yOp-planes) are presented and two series power expantions are realized from whiches processes that involves GOp-planes,yOp-planes, RR-forms, gravitons and gaugeons, are obtained. Finally non-standard GOp-planes and y-Op-planes are showed.

  20. Conceptual Design of Wave Plane

    DEFF Research Database (Denmark)

    Frigaard, Peter; Trewers, Andrew; Kofoed, Jens Peter;

    The Wave Plane is a patented Wave Energy device of the overtopping type, designed to capture potential as well as kinetic energy. This is as such different to other overtopping devices, who usually only focus on potential energy. If Wave Plane A/S can deliver the turbine technology to utilize both...

  1. Geography of irreducible plane sextics

    OpenAIRE

    Akyol, Ayşegül; Degtyarev, Alex

    2014-01-01

    We complete the equisingular deformation classification of irreducible singular plane sextic curves. As a by-product, we also compute the fundamental groups of the complement of all but a few maximizing sextics.

  2. Desmosomatidae (Isopoda: Asellota) from the abyssal plain to the east of the Kuril-Kamchatka Trench: New data on diversity with the description of two new species

    Science.gov (United States)

    Golovan, Olga A.

    2015-01-01

    In the material from the KuramBio expedition (Kuril-Kamchatka Biodiversity Study) Desmosomatidae constituted 20% of all isopod specimens (Crustacea: Malacostraca). 29 species in 10 genera (Desmosoma, Chelator, Eugerda, Eugerdella, Mirabilicoxa, Momedossa, Parvochelus, Prochelator, Pseudomesus and Torwolia) were found in the Pacific Ocean to the east of the Kuril-Kamchatka Trench at depth of 4830-5780 m. From these taxa five genera are reported for the first time in the Northwest Pacific, 26 species (90%) are new to science. Two species, Chelator michaeli sp.nov. and Prochelator keenani sp.nov. are described. Both described species appear to be very close to the two species previously known from the abyssal of the North Atlantic. Keys to the species of ChelatorHessler, 1970a and ProchelatorHessler, 1970a and the discussion of the genera are provided. The discussion of the Northwest Pacific desmosomatid fauna is presented. The diversity and the generic composition of the Desmosomatidae in the open abyssal of the Northwest Pacific are comparable with those known in other non-isolated deep-sea regions. On the contrary, the generic composition of Desmosomatidae in the adjacent semi-isolated Sea of Japan is impoverished versus the open Pacific abyssal.

  3. Fatty acid compositions and trophic relationships of shelled molluscs from the Kuril-Kamchatka Trench and the adjacent abyssal plain

    Science.gov (United States)

    Kharlamenko, Vladimir I.; Würzberg, Laura; Peters, Janna; Borisovets, Evgeny E.

    2015-01-01

    Fatty acid (FA) compositions of 12 species of shelled molluscs (gastropods, bivalves, and scaphopods) from the Kuril-Kamchatka Trench and the adjacent abyssal plain were studied. According to the results of multivariate statistical analysis, molluscs were divided into three groups. Group I consisted of three scaphopod species, the bivalve Nucula profundorum and the gastropod Solariella delicata. FA compositions of this group were characterized by high levels of 20:4(n-6). We suggest that the FA pattern found in scaphopods with high values of 20:4(n-6) is most likely typical for that of benthic organisms feeding preferentially on foraminiferans. Group II included the bivalves Neilonella politissima, Bentharca asperula, and Rhinoclama filatovae. Bivalves from the second group had elevated concentrations of 22:6(n-3), and the ratio of 20:4(n-6) to 20:5(n-3) was lower than 1. Bivalves from the second group had elevated concentrations of 22:6(n-3). We propose that high concentrations of this FA can be used as a specific marker for a carnivorous feeding mode of deep-sea benthic invertebrates. The bivalve Bathyspinula calcarella as well as the scaphopod Polyschides sakuraii could not unambiguously be assigned to one group. Within the similarity analysis they rather clustered together with the foraminiferans feeders (group I), but forming an own subgroup. In the PCA on the other hand, P. sakuraii showed a position close to the other bivalves, while B. calcarella had an intermediate position between all three groups. Group III consisted of the gastropods Tacita holoserica and Paracteocina sp., which contained high concentrations of 20:5(n-3) and 22:5(n-3). Both are known to exhibit a carnivorous/scavenging feeding strategy. The very low content of DHA in both species is on first sight not consistent with the suggested carnivorous feeding behavior. A characteristic feature of Paracteocina sp. and T. holoserica was a high level of 22:5(n-3), and HUFA ratios indicate that DHA

  4. Simple models for disequilibrium fractional melting and batch melting with application to REE fractionation in abyssal peridotites

    Science.gov (United States)

    Liang, Yan; Liu, Boda

    2016-01-01

    Disequilibrium melting arises when the kinetics of chemical exchange between a residual mineral and partial melt is sluggish compare to the rate of melting. To better understand the role of a finite crystal-melt exchange rate on trace element fractionation during mantle melting, we have developed a disequilibrium melting model for partial melting in an upwelling steady-state column. We use linear kinetics to approximate crystal-melt mass exchange rate and obtain simple analytical solutions for cases of perfect fractional melting and batch melting. A key parameter determining the extent of chemical disequilibrium during partial melting is an element specific dimensionless ratio (ε) defined as the melting rate relative to the solid-melt chemical exchange rate for the trace element of interest. In the case of diffusion in mineral limited chemical exchange, ε is inversely proportional to diffusivity of the element of interest. Disequilibrium melting is important for the trace element when ε is comparable to or greater than the bulk solid-melt partition coefficient for the trace element (k). The disequilibrium fractional melting model is reduced to the equilibrium perfect fractional melting model when ε is much smaller than k. Hence highly incompatible trace elements with smaller mobilities in minerals are more susceptible to disequilibrium melting than moderately incompatible and compatible trace elements. Effect of chemical disequilibrium is to hinder the extent of fractionation between residual solid and partial melt, making the residual solid less depleted and the accumulated melt more depleted in incompatible trace element abundances relative the case of equilibrium melting. Application of the disequilibrium fractional melting model to REE and Y abundances in clinopyroxene in abyssal peridotites from the Central Indian Ridge and the Vema Lithospheric Section, Mid-Atlantic Ridge revealed a positive correlation between the disequilibrium parameter ε and the

  5. Triticella minini - a new ctenostome bryozoan from the abyssal plain adjacent to the Kuril-Kamchatka Trench

    Science.gov (United States)

    Grischenko, Andrei V.; Chernyshev, Alexei V.

    2015-01-01

    A new species of ctenostome bryozoan, Triticella minini sp. nov., is described from the abyssal plain adjacent to the Kuril-Kamchatka Trench, based on material collected by the Russian-German deep-sea expedition KuramBio 2012. Colonies of T. minini sp. nov. were found attached to the oral spines of irregular sea urchin Echinosigra (Echinogutta) amphoraMironov, 1974 by means of rhizoid fibers that penetrated the substratum through circular borings. The specimens were examined by light microscopy, scanning electron microscopy, and confocal laser scanning microscopy with phalloidin and nuclear labeling. The description of T. minini sp. nov. combines a general taxonomic description with a description of the anatomy of the muscular system. The new species differs from congeners in lacking a stolon. It has an intertentacular organ. T. minini sp. nov. is the eleventh species described in the genus TriticellaDalyell, 1848, and the first record for this genus from the northwestern Pacific. The new species is the fifth ctenostome bryozoan known to occur in 5001-5500 m depth interval worldwide, and the deepest record reported for Triticella.

  6. Three new species and one new genus of abyssal Cumacea (Crustacea, Malacostraca, Peracarida) from the Kuril-Kamchatka Trench area

    Science.gov (United States)

    Lavrenteva, Anna V.; Mühlenhardt-Siegel, Ute

    2015-01-01

    Only two species of crustacean Cumacea have been reported in publications for the Kuril-Kamchatka Trench area after nine expeditions on board of the RV "Vityaz". During the KuramBio expedition 2012 to the Kuril-Kamchatka Trench and the adjacent abyssal plain at depths 4830-5780 m no less than 72 species of cumaceans from 23 genera and 6 families were sampled. Five genera were recorded for the first time in the studied region: the genera Pseudoleptostyloides and Platycuma were detected for the first time for the Pacific Ocean; Cyclaspoides, Bathylamprops and Styloptocuma were firstly sampled in North Pacific. About 90% of the sampled species appear to be new to science. Three new deep-sea cumacean species and one new genus from the Kurile Kamchatka area are described in the present paper: Abyssoleucon tzarevae gen. n., sp. n. belonging to the family Leuconidae, Cyclaspoides borisovetsi sp. n. and Bathycuma sonne sp. n. of the family Bodotriidae. A distribution map for the species of the genus Cyclaspoides is provided.

  7. Submarine ridges do not prevent large-scale dispersal of abyssal fauna: A case study of Mesocletodes (Crustacea, Copepoda, Harpacticoida)

    Science.gov (United States)

    Menzel, Lena; George, Kai Horst; Arbizu, Pedro Martínez

    2011-08-01

    We examined the large-scale distribution of deep-sea harpacticoid copepods at the species level, in order to clarify the underlying processes of copepod dispersal. The study was based on samples collected from 12 regions and a total of 113 stations: 57 stations at depths between 1107 and 5655 m on abyssal plains in the South and North Atlantic, Southern Ocean, southern Indian Ocean, and the Pacific Ocean, and 56 stations above 900 m in the North Atlantic and eastern Mediterranean Sea. We chose the genus Mesocletodes Sars, 1909 as an ideal group to study the large-scale distribution of harpacticoid copepods in the deep oceans. Clear apomorphies and a comparatively large body size of about 1 mm allow rapid recognition of allied species in meiofauna samples. In addition, Mesocletodes represents more than 50% of the family Argestidae Por, 1986, one of the most abundant harpacticoid families in the deep sea. The geographical distributions of 793 adult females of Mesocletodes belonging to 61 species throughout the South and North Atlantic, Southern Ocean, southern Indian Ocean, Pacific Ocean, and eastern Mediterranean Sea indicated that most species are cosmopolitan. Neither the topography of the sea bottom nor long distances seem to prevent species from dispersing. Passive transport by bottom currents after resuspension is likely the propulsive factor for the dispersal of Harpacticoida, while plate tectonics and movement of individuals in the sediment may play relatively minor roles.

  8. Hyalinecia (sic) Edwardsi Roule, 1898-the enigmatic ghost from abyssal depths-redescribed as Nothria edwardsi (Annelida: Onuphidae).

    Science.gov (United States)

    Arias, Andrés; Paxton, Hannelore

    2016-01-01

    The deep sea is one of the largest ecosystems on earth, extending from 200 m, where sunlight becomes inadequate for photosynthesis, to the deepest trenches. However, it is still one of the least explored. Polychaetes are among the dominant groups in these environments worldwide and play a critical role in the deep sea food chain. Within polychaetes, the onuphids are one the best represented families from 2000 m deep to the hadal zone, with 46 recorded species (Paterson et al. 2009). Hyalinoecia edwardsi Roule, 1898 is one of the early described abyssal onuphids. The species was described from the Talisman station 136, located between the Azores archipelago and the Iberian Peninsula (referred as "l'Espagne") at 4255 m depth (Roule 1898). The original description is rather brief without illustrations and the species was characterised as follows: thick antennae, lateral ones reaching chaetiger 3; first chaetiger twice as long as second one; parapodia of first chaetiger with thick falcate hooks; parapodia of second chaetiger with bidentate hooks; parapodia of third chaetiger with limbate chaetae; following chaetigers with limbate, pectinate chaetae and subacicular hooks; oval tube looking flattened and covered by small particles, mainly quartzites of different colours (Roule 1898). PMID:27515609

  9. Links between surface productivity and deep ocean particle flux at the Porcupine Abyssal Plain (PAP) sustained observatory

    Science.gov (United States)

    Frigstad, H.; Henson, S. A.; Hartman, S. E.; Omar, A. M.; Jeansson, E.; Cole, H.; Pebody, C.; Lampitt, R. S.

    2015-04-01

    In this study we present hydrography, biogeochemistry and sediment trap observations between 2003 and 2012 at Porcupine Abyssal Plain (PAP) sustained observatory in the northeast Atlantic. The time series is valuable as it allows for investigation of the link between surface productivity and deep ocean carbon flux. The region is a perennial sink for CO2, with an average uptake of around 1.5 mmol m-2 d-1. The average monthly drawdowns of inorganic carbon and nitrogen were used to quantify the net community production (NCP) and new production, respectively. Seasonal NCP and new production were found to be 4.57 ± 0.27 mol C m-2 and 0.37 ± 0.14 mol N m-2. The Redfield ratio was high (12), and the production calculated from carbon was higher than production calculated from nitrogen, which is indicative of carbon overconsumption. The export ratio and transfer efficiency were 16 and 4%, respectively, and the site thereby showed high flux attenuation. Particle tracking was used to examine the source region of material in the sediment trap, and there was large variation in source regions, both between and within years. There were higher correlations between surface productivity and export flux when using the particle-tracking approach, than by comparing with the mean productivity in a 100 km box around the PAP site. However, the differences in correlation coefficients were not significant, and a longer time series is needed to draw conclusions on applying particle tracking in sediment trap analyses.

  10. Explosive plane-wave lens

    Science.gov (United States)

    Marsh, Stanley P.

    1988-01-01

    An explosive plane-wave air lens which enables a spherical wave form to be converted to a planar wave without the need to specially machine or shape explosive materials is described. A disc-shaped impactor having a greater thickness at its center than around its periphery is used to convert the spherical wave into a plane wave. When the wave reaches the impactor, the center of the impactor moves first because the spherical wave reaches the center of the impactor first. The wave strikes the impactor later in time as one moves radially along the impactor. Because the impactor is thinner as one moves radially outward, the velocity of the impactor is greater at the periphery than at the center. An acceptor explosive is positioned so that the impactor strikes the acceptor simultaneously. Consequently, a plane detonation wave is propagated through the acceptor explosive.

  11. Plane waves as tractor beams

    Science.gov (United States)

    Forgács, Péter; Lukács, Árpád; Romańczukiewicz, Tomasz

    2013-12-01

    It is shown that in a large class of systems, plane waves act as tractor beams: i.e., an incident plane wave can exert a pulling force on the scatterer. The underlying physical mechanism for the pulling force is due to the sufficiently strong scattering of the incoming wave into another mode carrying more momentum, in which case excess momentum is created behind the scatterer. This tractor beam or negative radiation pressure (NRP) effect, is found to be generic in systems with multiple scattering channels. In a birefringent medium, electromagnetic plane waves incident on a thin plate exert NRP of the same order of magnitude as optical radiation pressure, while in artificial dielectrics (metamaterials), the magnitude of NRP can even be macroscopic. In two dimensions, we study various scattering situations on vortices, and NRP is shown to occur by the scattering of heavy baryons into light leptons off cosmic strings, and by neutron scattering off vortices in the XY model.

  12. Evidences of intraplate deformation in the West Madeira Abyssal Plain (eastern North Atlantic) from seismic reflection and multibeam swath bathymetry data

    Science.gov (United States)

    Roque, C.; Simões, M.; Lourenço, N.; Pinto de Abreu, M.

    2009-04-01

    The West Madeira Abyssal Plain is located in the eastern North Atlantic off Madeira Islands, forming part of the Canary Basin and reaching a mean water depth of 5300 m. This region is also located within Africa plate at about 500 km southwards from the Açores-Gibraltar plate boundary, and for that reason lacks seismic activity. Although this region being located in an intraplate setting, the presence of faulted sediments was reported in several works published during the eighties of last century following a study conducted in late 1970s to evaluate the feasibility of disposal of high-level radioactive wastes in the ocean. According these works, the Madeira Abyssal Plain sediments are cut by many normal growth faults and this deformation is a result of compaction and dewatering of the sediments. Evidences of tectonic deformation of oceanic sediments in intraplate settings are uncommon, but folded sediments and reverse faults extending into the basement, were recognized in the equatorial Indian Ocean and in the West African continental margin. Recently, during 2006 multi-channel seismic reflection and multibeam swath bathymetry surveys were carried out in the West Madeira Abyssal Plain by EMEPC in order to prepare the Portuguese proposal for the extension of the continental shelf. The seismic lines were acquired onboard R/V Akademik Shatskiy using a source of 5720 cu in bolt gun array, cable length of 7950 m and shot interval of 50.00 m. The multibeam swath bathymetry was acquired onboard NRP Gago Coutinho, and allowed a high resolution mapping of the main geomorphological features. The multichannel seismic lines, oriented WNW-ESE, image the Madeira island lower slope located at about 4000 m water depth and the almost flat abyssal plain at about 5300 m water depth. These seismic lines show a thick sedimentary succession that reaches a maximum thickness of about 1.5 sec twt in the deepest parts of the West Madeira Abyssal Plain, overlying an irregular diffractive

  13. Plane waves in noncommutative fluids

    International Nuclear Information System (INIS)

    We study the dynamics of the noncommutative fluid in the Snyder space perturbatively at the first order in powers of the noncommutative parameter. The linearized noncommutative fluid dynamics is described by a system of coupled linear partial differential equations in which the variables are the fluid density and the fluid potentials. We show that these equations admit a set of solutions that are monochromatic plane waves for the fluid density and two of the potentials and a linear function for the third potential. The energy–momentum tensor of the plane waves is calculated.

  14. Plane waves in noncommutative fluids

    Science.gov (United States)

    Abdalla, M. C. B.; Holender, L.; Santos, M. A.; Vancea, I. V.

    2013-08-01

    We study the dynamics of the noncommutative fluid in the Snyder space perturbatively at the first order in powers of the noncommutative parameter. The linearized noncommutative fluid dynamics is described by a system of coupled linear partial differential equations in which the variables are the fluid density and the fluid potentials. We show that these equations admit a set of solutions that are monochromatic plane waves for the fluid density and two of the potentials and a linear function for the third potential. The energy-momentum tensor of the plane waves is calculated.

  15. Plane waves in noncommutative fluids

    Energy Technology Data Exchange (ETDEWEB)

    Abdalla, M.C.B., E-mail: mabdalla@ift.unesp.br [Instituto de Física Teórica, UNESP, Universidade Estadual Paulista, Rua Dr. Bento Teobaldo Ferraz 271, Bloco 2, Barra-Funda, Caixa Postal 70532-2, 01156-970, São Paulo, SP (Brazil); Holender, L., E-mail: holender@ufrrj.br [Grupo de Física Teórica e Matemática Física, Departamento de Física, Universidade Federal Rural do Rio de Janeiro (UFRRJ), Cx. Postal 23851, BR 465 Km 7, 23890-000 Seropédica, RJ (Brazil); Santos, M.A., E-mail: masantos@cce.ufes.br [Departamento de Física e Química, Universidade Federal do Espírito Santo (UFES), Avenida Fernando Ferarri S/N, Goiabeiras, 29060-900 Vitória, ES (Brazil); Vancea, I.V., E-mail: ionvancea@ufrrj.br [Grupo de Física Teórica e Matemática Física, Departamento de Física, Universidade Federal Rural do Rio de Janeiro (UFRRJ), Cx. Postal 23851, BR 465 Km 7, 23890-000 Seropédica, RJ (Brazil)

    2013-08-01

    We study the dynamics of the noncommutative fluid in the Snyder space perturbatively at the first order in powers of the noncommutative parameter. The linearized noncommutative fluid dynamics is described by a system of coupled linear partial differential equations in which the variables are the fluid density and the fluid potentials. We show that these equations admit a set of solutions that are monochromatic plane waves for the fluid density and two of the potentials and a linear function for the third potential. The energy–momentum tensor of the plane waves is calculated.

  16. Force Lines in Plane Stress

    DEFF Research Database (Denmark)

    Rathkjen, Arne

    A state of plane stress is illustrated by means of two families of curves, each family representing constant values of a derivative of Airy's stress function. The two families of curves form a map giving in the first place an overall picture of regions of high and low stress, and in the second...

  17. Plane and parabolic solar panels

    OpenAIRE

    Sales, J. H. O.; Suzuki, A.T.

    2009-01-01

    We present a plane and parabolic collector that absorbs radiant energy and transforms it in heat. Therefore we have a panel to heat water. We study how to increment this capture of solar beams onto the panel in order to increase its efficiency in heating water.

  18. Linear Instability of the Plane Couette and Plane Poiseuille Flows

    CERN Document Server

    Chefranov, Sergey G

    2015-01-01

    We show possibility of the Plane Couette (PC) flow instability for Reynolds number Re>Reth=140. This new result of the linear hydrodynamic stability theory is obtained on the base of refusal from the traditionally used assumption on longitudinal periodicity of the disturbances along the direction of the fluid flow. We found that earlier existing understanding on the linear stability of this flow for any arbitrary large Reynolds number is directly related with an assumption on the separation of the variables of the spatial variability for the disturbance field and their periodicity in linear theory of stability. By the refusal from the pointed assumptions also for the Plane Poiseuille (PP) flow, we get a new threshold Reynolds value Reth=1040 that with 4% accuracy agrees with the experiment contrary to more than 500% discrepancy for the earlier known estimate Reth=5772 obtained in the frame of the linear theory but when using the "normal" disturbance form (S. A. Orszag, 1971).

  19. Gravitational Couplings for y-Gop-Planes

    CERN Document Server

    Ospina-Giraldo, J F

    2000-01-01

    The Wess-Zumino action for y deformed and generalized orientifold planes (yGOp-planes) is presented and one power expantion is realized from which processes that involves yGOp-planes, RR-forms, gravitons and gaugeons, are obtained. Finally non-standard yGOp-planes are showed.

  20. Gravitational Couplings for Generalized Orientifold Planes

    CERN Document Server

    Ospina-Giraldo, J F

    2000-01-01

    The Wess-Zumino action for generalized orientifold planes (GOp-planes) is presented and a series power expantion is realized from which processes that involves GOp-planes, RR-forms, gravitons and gaugeons, are obtained. Finally non-standard GOp-planes are showed.

  1. Optimization of starshades: focal plane versus pupil plane

    Science.gov (United States)

    Flamary, R.; Aime, C.

    2014-09-01

    We search for the best possible transmission for an external occulter coronagraph that is dedicated to the direct observation of terrestrial exoplanets. We show that better observation conditions are obtained when the flux in the focal plane is minimized in the zone in which the exoplanet is observed, instead of for the total flux received by the telescope. We describe the transmission of the occulter as a sum of basis functions. For each element of the basis, we numerically computed the Fresnel diffraction at the aperture of the telescope and the complex amplitude at its focus. The basis functions are circular disks that are linearly apodized over a few centimeters (truncated cones). We complemented the numerical calculation of the Fresnel diffraction for these functions by a comparison with pure circular disks (cylinder) for which an analytical expression, based on a decomposition in Lommel series, is available. The technique of deriving the optimal transmission for a given spectral bandwidth is a classical regularized quadratic minimization of intensities, but linear optimizations can be used as well. Minimizing the integrated intensity on the aperture of the telescope or for selected regions of the focal plane leads to slightly different transmissions for the occulter. For the focal plane optimization, the resulting residual intensity is concentrated behind the geometrical image of the occulter, in a blind region for the observation of an exoplanet, and the level of background residual starlight becomes very low outside this image. Finally, we provide a tolerance analysis for the alignment of the occulter to the telescope, which also favors the focal plane optimization. This means that telescope offsets of a few decimeters do not strongly reduce the efficiency of the occulter.

  2. Do abyssal scavengers use phytodetritus as a food resource? Video and biochemical evidence from the Atlantic and Mediterranean

    Science.gov (United States)

    Jeffreys, Rachel M.; Lavaleye, Marc S. S.; Bergman, Magda J. N.; Duineveld, Gerard C. A.; Witbaard, Rob

    2011-04-01

    Deep-sea benthic communities derive their energetic requirements from overlying surface water production, which is deposited at the seafloor as phytodetritus. Benthic invertebrates are the primary consumers of this food source, with deep-sea fish at the top of the trophic hierarchy. Recently, we demonstrated with the use of baited cameras that macrourid fish rapidly respond to and feed vigorously on large plant food falls mimicked by spinach ( Jeffreys et al., 2010). Since higher plant remains are scarce in the deep-sea, with the exception of canyons, where terrestrial material has been observed, these results led us to ask if a more commonly documented plant material i.e. phytodetritus might form a food source for deep-sea fish and mobile scavenging megafauna. We simulated a phytodetritus dump at the seafloor in two contrasting environments (1) the NE Atlantic where carpets of phytodetritus have been previously observed and (2) the oligotrophic western Mediterranean, where the deposition of phytodetritus at the seafloor is a rare occurrence. We recorded the response of the scavenging fauna using an in situ benthic lander equipped with baited time-lapse cameras. In the NE Atlantic at 3000 m, abyssal macrourids and cusk-eels were observed ingesting the phytodetritus. The phytodetrital patch was significantly diminished within 2 h. Abundance estimates calculated from first arrival times of macrourids at the phytodetrital patch in the Atlantic corresponded with abundance estimates from video-transect indicating that fish were attracted to the scent of phytodetrital bait. In contrast to this, in the western Mediterranean at 2800 m a single macrourid was observed investigating the phytodetrital patch but did not feed from it. The phytodetrital patch was significantly diminished within 6.5 h as a result of mainly invertebrate activity. At 1900 m, Lepidion lepidion was observed near the lander and the bait, but did not feed. The phytodetrital patch remained intact until

  3. Water in orthopyroxene from abyssal spinel peridotites of the East Pacific Rise (ODP Leg 147: Hess Deep)

    Science.gov (United States)

    Hesse, Kirsten T.; Gose, Jürgen; Stalder, Roland; Schmädicke, Esther

    2015-09-01

    Abyssal spinel peridotites from Hess Deep, East Pacific Rise (ODP Leg 147) were investigated concerning their major, minor, and trace element mineral chemistry and the incorporation of structural water in orthopyroxene. The rocks are partially serpentinized harzburgites containing primary minerals of olivine, orthopyroxene, clinopyroxene, and spinel. Orthopyroxene is enstatitic with Mg# (Mg/(Mg + Fe)) between 0.90 and 0.92 and Al2O3 from 0.5 to 2.9 wt.%. The residual harzburgite experienced high degrees of melt removal in the spinel peridotite stability field. The average degree of partial melting was calculated to be 17.5% (range: 16.4-17.8%). Trace element data of ortho- and clinopyroxenes reflect this strong depletion, characteristic for the restitic nature of abyssal peridotites. Mantle re-equilibration temperatures around 1000 °C indicate that, after melt extraction and before exhumation to the ocean floor, the rocks experienced significant cooling in the spinel peridotite facies. Water contents of orthopyroxene range from 86 to 233 wt. ppm H2O with an average concentration of 142 wt. ppm H2O. These results represent the first data on water contents in the sub-pacific mantle obtained by direct measurements of sub-oceanic peridotite. The water contents are not related to mineral chemistry, stratigraphy, melting degree, mantle equilibrium conditions or oxidation state. Calculated post-melt peridotite water contents vary between 40 and 100 wt. ppm H2O. Compared to Mid-Atlantic Ridge peridotites, the East Pacific Rise samples of Leg 147 contain somewhat lower water concentrations than samples from Leg 153 and considerably higher contents than those of Leg 209 (Gose et al., 2009; Schmädicke et al., 2011). In Leg 147, the strongest OH absorbtion band occurs at 3420 cm- 1, wheras orthopyroxene from MAR peridotite (Legs 153 and 209) has its strongest absorbtion band at 3566 and 3522 cm- 1. The mantle equilibrium temperature of Leg 147 peridotites is lower than that

  4. The Grushin plane and quasiconformal Jacobians

    OpenAIRE

    Meyerson, William

    2011-01-01

    We construct a quasiconformal map from the Grushin plane to the Euclidean plane. Then, we generalize the Grushin plane slightly and explain how the Grushin plane can serve as an intermediary in dealing with quasiconformal maps on Euclidean spaces. In particular, we construct a family of quasiconformal embeddings of the Euclidean plane into larger Euclidean spaces whose Jacobians fail to be locally integrable on a line.

  5. Fate of corrosion products released from stainless steel in marine sediments and seawater. Part 4: Hatteras abyssal red clay

    International Nuclear Information System (INIS)

    A study in which neutron-activated 347 stainless steel was exposed to surficial sediment from a site in the Hatteras Abyssal Plain of the Northwest Atlantic Ocean is described. This sediment consists of approx. 20% CaCO3, which could lead to the formation of calcareous scale on the metal surface and reduce the corrosion rate. The distribution of indigenous metals among different chemical fractions shows that extractable Cr, Mn, Fe, Co, and Zn were associated with amorphous Mn and Fe oxides. Most of the remaining extractable Cr, and about a third of the extractable Cu appear to have been weakly complexed. Major fractions (25 to 36%) of extractable Mn, Co and Ni were present as adsorbed cations. Organic complexation appears to account for a large amount of extractable Fe, Ni, Cu and Zn. Neutron-activated 347 stainless steel specimens were exposed to sediment slurry under aerobic and non-oxygenated conditions for a period of 94 days. The redox potential measurements for air-sparged and N2, CO2-sparged sediment slurries were +410 and +60 mv, respectively. The presence of 02 produced increased amounts of corrosion products. Chemical extraction showed that relatively labile substances constituted about 84% of the 60Co activity released in aerated sediment. Relatively labile substances constitute about 82% of the total 60Co activity released under non-oxygenated conditions. A large fraction of 60Co which was in the soluble or easily dissolved forms under non-oxygenated conditions appears to have been more strongly adsorbed to the sediment under aerated conditions

  6. Application of Markov Chain Monte Carlo Method to Mantle Melting: An Example from REE Abundances in Abyssal Peridotites

    Science.gov (United States)

    LIU, B.; Liang, Y.

    2015-12-01

    Markov chain Monte Carlo (MCMC) simulation is a powerful statistical method in solving inverse problems that arise from a wide range of applications, such as nuclear physics, computational biology, financial engineering, among others. In Earth sciences applications of MCMC are primarily in the field of geophysics [1]. The purpose of this study is to introduce MCMC to geochemical inverse problems related to trace element fractionation during concurrent melting, melt transport and melt-rock reaction in the mantle. MCMC method has several advantages over linearized least squares methods in inverting trace element patterns in basalts and mantle rocks. First, MCMC can handle equations that have no explicit analytical solutions which are required by linearized least squares methods for gradient calculation. Second, MCMC converges to global minimum while linearized least squares methods may be stuck at a local minimum or converge slowly due to nonlinearity. Furthermore, MCMC can provide insight into uncertainties of model parameters with non-normal trade-off. We use MCMC to invert for extent of melting, amount of trapped melt, and extent of chemical disequilibrium between the melt and residual solid from REE data in abyssal peridotites from Central Indian Ridge and Mid-Atlantic Ridge. In the first step, we conduct forward calculation of REE evolution with melting models in a reasonable model space. We then build up a chain of melting models according to Metropolis-Hastings algorithm to represent the probability of specific model. We show that chemical disequilibrium is likely to play an important role in fractionating LREE in residual peridotites. In the future, MCMC will be applied to more realistic but also more complicated melting models in which partition coefficients, diffusion coefficients, as well as melting and melt suction rates vary as functions of temperature, pressure and mineral compositions. [1]. Sambridge & Mosegarrd [2002] Rev. Geophys.

  7. Spatio-temporal changes in the distribution of phytopigments and phytoplanktonic groups at the Porcupine Abyssal Plain (PAP) site

    Science.gov (United States)

    Smythe-Wright, Denise; Boswell, Stephen; Kim, Young-Nam; Kemp, Alan

    2010-08-01

    We have made a comprehensive study of pigment distributions and microscopically determined phytoplankton abundances within the Porcupine Abyssal Plain (PAP) location in the North Atlantic to better understand phytoplankton variability, and make some suggestions regarding the composition of the material falling to the sea bed and its impacts on benthic organisms such as Amperima rosea. The area has been the focus of many studies of ocean fluxes and benthic communities over recent years, but little attention has been given to the spatio-temporal variability in the surface waters. Dawn casts over a 12-day period at the PAP mooring site (48.83°N 16.5°W) revealed the presence of only one species, the diatom Actinocyclus exiguus, at bloom concentrations for just 5 days. Smaller populations of other diatoms and the dinoflagellates Gymnodinium and Gyrodinium were also present at this time. Following this 5-day interval, a mixed population of small-sized dinoflagellates, prymnesiophytes, prasinophytes, chrysophytes and cyanobacteria occurred. It is clear from concomitant CTD/bottle surveys that rapid changes in phytoplankton community structure at a fixed time series position do not necessarily reflect a degradation or manifestation of one particular species but rather represent the movement of eddies and other water masses within very short timescales. These cause substantial variability in the species class and size fraction that may explain the variability in carbon export that has been seen at the PAP site. We also make some suggestions on the variable composition of the material falling to the seabed and its impact on benthic organisms such as Amperima rosea.

  8. Links between surface productivity and deep ocean particle flux at the Porcupine Abyssal Plain (PAP sustained observatory

    Directory of Open Access Journals (Sweden)

    H. Frigstad

    2015-04-01

    Full Text Available In this study we present hydrography, biogeochemistry and sediment trap observations between 2003 and 2012 at Porcupine Abyssal Plain (PAP sustained observatory in the northeast Atlantic. The time series is valuable as it allows for investigation of the link between surface productivity and deep ocean carbon flux. The region is a perennial sink for CO2, with an average uptake of around 1.5 mmol m−2 d−1. The average monthly drawdowns of inorganic carbon and nitrogen were used to quantify the net community production (NCP and new production, respectively. Seasonal NCP and new production were found to be 4.57 ± 0.27 mol C m−2 and 0.37 ± 0.14 mol N m−2. The Redfield ratio was high (12, and the production calculated from carbon was higher than production calculated from nitrogen, which is indicative of carbon overconsumption. The export ratio and transfer efficiency were 16 and 4%, respectively, and the site thereby showed high flux attenuation. Particle tracking was used to examine the source region of material in the sediment trap, and there was large variation in source regions, both between and within years. There were higher correlations between surface productivity and export flux when using the particle-tracking approach, than by comparing with the mean productivity in a 100 km box around the PAP site. However, the differences in correlation coefficients were not significant, and a longer time series is needed to draw conclusions on applying particle tracking in sediment trap analyses.

  9. The general relativistic infinite plane

    CERN Document Server

    Jones, Preston; Ragsdale, Michael; Singleton, Douglas

    2007-01-01

    Uniform fields are one of the simplest and most pedagogically useful examples in introductory courses on electrostatics or Newtonian gravity. In general relativity there have been several proposals as to what constitutes a uniform field. In this article we examine two metrics that can be considered the general relativistic version of the infinite plane with finite mass per unit area. The first metric is the 4D version of the 5D "brane" world models which are the starting point for many current research papers. The second case is the cosmological domain wall metric. We examine to what extent these different metrics match or deviate from our Newtonian intuition about the gravitational field of an infinite plane. These solutions provide the beginning student in general relativity both computational practice and conceptual insight into Einstein's field equations. In addition they do this by introducing the student to material that is at the forefront of current research.

  10. Plane waves as tractor beams

    CERN Document Server

    Forgács, Péter; Romańczukiewicz, Tomasz

    2013-01-01

    It is shown that in a large class of systems plane waves can act as tractor beams: i.e., an incident plane wave can exert a pulling force on the scatterer. The underlying physical mechanism for the pulling force is due to the sufficiently strong scattering of the incoming wave into another mode having a larger wave number, in which case excess momentum is created behind the scatterer. Such a tractor beam or negative radiation pressure effect arises naturally in systems where the coupling between the scattering channels is due to Aharonov-Bohm (AB) gauge potentials. It is demonstrated that this effect is also present if the AB potential is an induced, ("artificial") gauge potential such as the one found in J. March-Russell, J. Preskill, F. Wilczek, Phys. Rev. Lett. 58 2567 (1992).

  11. Inter-annual dynamics of abyssal polychaete communities in the North East Pacific and North East Atlantic—A family-level study

    Science.gov (United States)

    Laguionie-Marchais, C.; Billett, D. S. M.; Paterson, G. L. D.; Ruhl, H. A.; Soto, E. H.; Smith, K. L., Jr.; Thatje, S.

    2013-05-01

    Characterising how deep-sea communities change on contemporary time-scales and understanding underlying ecosystem processes has become important under changing climate and the rise in the exploitation of deep-sea resources. However, little is known about these dynamics and processes. Long-term observations from which inter-annual variations can be detected are scarce in the deep sea. This study examines inter-annual changes in density, family richness and evenness, family and functional group rank abundance distributions of infaunal polychaetes at two abyssal stations in the North East Pacific (Station M, 1991 to 2005) and in the North East Atlantic (Porcupine Abyssal Plain, 1991 to 1999). The two long-term data sets were used to investigate not only if polychaete community structure and composition varied at inter-annual scales in terms of diversity and rank abundance distributions but also if any changes were related to previous observations in megafauna and environmental factors at each locality. The polychaete community structure at each locality was analysed using univariate statistics as well as multivariate ordination techniques based on Bray-Curtis similarity of the yearly family density. Sub-surface deposit feeders, such as Paraonidae, dominated the North East Pacific, whereas surface deposit feeders, such as Cirratulidae, dominated the North East Atlantic. Both stations showed inter-annual variations in density, family evenness and rank abundance distributions. The greatest changes occurred in 1998 in both time series when polychaete densities peaked, and switches in the rank abundance of the most abundant families and functional groups took place. Inter-annual variations in the polychaete community were correlated with a limited number of holothurian species changes, but no correlation was found with particulate organic matter flux or climate indices. Ecological and environmental factors behind the family-level changes remain elusive. Overall, changes in

  12. The response of abyssal organisms to low pH conditions during a series of CO2-release experiments simulating deep-sea carbon sequestration

    Science.gov (United States)

    Barry, J. P.; Buck, K. R.; Lovera, C.; Brewer, P. G.; Seibel, B. A.; Drazen, J. C.; Tamburri, M. N.; Whaling, P. J.; Kuhnz, L.; Pane, E. F.

    2013-08-01

    The effects of low-pH, high-pCO2 conditions on deep-sea organisms were examined during four deep-sea CO2 release experiments simulating deep-ocean C sequestration by the direct injection of CO2 into the deep sea. We examined the survival of common deep-sea, benthic organisms (microbes; macrofauna, dominated by Polychaeta, Nematoda, Crustacea, Mollusca; megafauna, Echinodermata, Mollusca, Pisces) exposed to low-pH waters emanating as a dissolution plume from pools of liquid carbon dioxide released on the seabed during four abyssal CO2-release experiments. Microbial abundance in deep-sea sediments was unchanged in one experiment, but increased under environmental hypercapnia during another, where the microbial assemblage may have benefited indirectly from the negative impact of low-pH conditions on other taxa. Lower abyssal metazoans exhibited low survival rates near CO2 pools. No urchins or holothurians survived during 30-42 days of exposure to episodic, but severe environmental hypercapnia during one experiment (E1; pH reduced by as much as ca. 1.4 units). These large pH reductions also caused 75% mortality for the deep-sea amphipod, Haploops lodo, near CO2 pools. Survival under smaller pH reductions (ΔpH<0.4 units) in other experiments (E2, E3, E5) was higher for all taxa, including echinoderms. Gastropods, cephalopods, and fish were more tolerant than most other taxa. The gastropod Retimohnia sp. and octopus Benthoctopus sp. survived exposure to pH reductions that episodically reached -0.3 pH units. Ninety percent of abyssal zoarcids (Pachycara bulbiceps) survived exposure to pH changes reaching ca. -0.3 pH units during 30-42 day-long experiments.

  13. Twisted sectors from plane partitions

    CERN Document Server

    Datta, Shouvik; Li, Wei; Peng, Cheng

    2016-01-01

    Twisted sectors arise naturally in the bosonic higher spin CFTs at their free points, as well as in the associated symmetric orbifolds. We identify the coset representations of the twisted sector states using the description of W_\\infty representations in terms of plane partitions. We confirm these proposals by a microscopic null-vector analysis, and by matching the excitation spectrum of these representations with the orbifold prediction.

  14. Plane SPDC-Quantum Mirror

    OpenAIRE

    Ion, M. L. D.; Ion, D. B.

    2013-01-01

    In this paper the kinematical correlations from the phase conjugated optics (equivalently with crossing symmetric spontaneous parametric down conversion (SPDC) phenomena) in the nonlinear crystals are used for the description of a new kind of optical device called SPDC-quantum mirrors. Then, some important laws of the plane SPDC-quantum mirrors combined with usual mirrors or lens are proved only by using geometric optics concepts. In particular, these results allow us to obtain a new interpre...

  15. Force Lines in Plane Stress

    OpenAIRE

    Rathkjen, Arne

    1994-01-01

    A state of plane stress is illustrated by means of two families of curves, each family representing constant values of a derivative of Airy's stress function. The two families of curves form a map giving in the first place an overall picture of regions of high and low stress, and in the second place, the map comprises a complete graphic representation of the stress at any point.

  16. Air ionization wire plane chamber

    International Nuclear Information System (INIS)

    Radiation Measurement for protection level instrumentation requires large number of detectors. Since the number is large, the detector should be cost effective and yet should have good sensitivity. Gas detectors with presently available microelectronics and signal processing capabilities opened a new era in radiation monitoring. Present paper describes the use of air filled multi anode grid planes as detector for alpha detection. Due to multiple anode wire planes, the charge collection efficiency of the air ionization chamber is higher as compared to conventional ionization chamber. The signal from this Wire Plane Chamber (WPC) has a faster and narrower pulse shape as compared to conventional two-electrode chamber of similar dimensions. The reduction in capacitance also improves the signal to noise ratio so that air can be used as the ionization medium without any special cleaning procedure etc and it may be possible to use even engineering plastic as the structural material for the chamber. The paper gives the results obtained so far with this air ionization chamber. (author)

  17. Generalized plane gravitational waves of non-symmetric unified field theories in plane symmetry

    OpenAIRE

    Bhoyar, Sanjiv R.; Ajit Deshmukh

    2012-01-01

    In this paper we investigated the plane wave solutions of both the weak and strong non-symmetric unified field equations of Einstein and Bonner in a generalized plane symmetric space-time in the sense of Taub [Ann. Math. 53, 472 (1951)] for plane gravitational waves. We show that the plane wave solutions of Einstein and Bonner field equations exist in plane symmetry.

  18. Plane wave diffraction by a perfectly transparent half-plane.

    Science.gov (United States)

    Anokhov, Sergey P

    2007-09-01

    The exact solution is found for plane wave diffraction by an arbitrary phase step. The analysis is performed by using the Huygens-Fresnel principle and the superposition integral, where every secondary wave was identified with the surface element field of the actual electromagnetic wave. The dependence of the total field structure on the height of the phase step is analyzed. The formation algorithm is demonstrated for the primary wave component of the edge diffraction, which has a singular nature and determines nearly all physical properties of this phenomenon. PMID:17767219

  19. Plane SPDC-Quantum Mirror

    CERN Document Server

    Ion, M L D

    2013-01-01

    In this paper the kinematical correlations from the phase conjugated optics (equivalently with crossing symmetric spontaneous parametric down conversion (SPDC) phenomena) in the nonlinear crystals are used for the description of a new kind of optical device called SPDC-quantum mirrors. Then, some important laws of the plane SPDC-quantum mirrors combined with usual mirrors or lens are proved only by using geometric optics concepts. In particular, these results allow us to obtain a new interpretation of the recent experiments on the two-photon geometric optics.

  20. Distributed Storage in the Plane

    OpenAIRE

    Altman, Eitan; Avrachenkov, Konstantin; Goseling, Jasper

    2014-01-01

    We consider storage devices located in the plane according to a general point process and specialize the results for the homogeneous Poisson process. A large data file is stored at the storage devices, which have limited storage capabilities. Hence, they can only store parts of the data. Clients can contact the storage devices to retrieve the data.We compare the expected cost of obtaining the complete data under uncoded as well as coded data allocation strategies. It is shown that for the gen...

  1. Semantic versus syntactic cutting planes

    Czech Academy of Sciences Publication Activity Database

    Filmus, Y.; Hrubeš, Pavel; Lauria, M.

    Dagstuhl: Schloss Dagstuhl, Leibniz-Zentrum für Informatik, 2016 - (Ollinger, N.; Vollmer, H.), s. 1-13. (Leibniz International Proceedings in Informatics. 47). ISBN 978-3-95977-001-9. ISSN 1868-8969. [33rd Symposium on Theoretical Aspects of Computer Science (STACS 2016). Orléans (FR), 17.02.2016-20.02.2016] EU Projects: European Commission(XE) 339691 - FEALORA Keywords : proof complexity * cutting planes * lower bounds Subject RIV: BA - General Mathematics http://drops.dagstuhl.de/opus/frontdoor.php?source_opus=5736

  2. Plane waves in noncommutative fluids

    CERN Document Server

    Holender, M C B AbdallaL; Vancea, I V

    2012-01-01

    We study the dynamics of the noncommutative fluid in the Snyder space from the perturbative point of view. To this end, the relevant quantities are treated as series in powers of the noncommutative parameter. At the Planck scale, the relevant terms are of first order and the dynamics is described by a system of coupled linear partial differential equations in which the variables are the fluid density and the fluid potentials. We show that these equations admit a set of solutions that are monocromatic plane waves for the fluid density and two of the potentials and linear for the third potential. The energy-momentum tensor of these solutions is calculated.

  3. SNAP Satellite Focal Plane Development

    International Nuclear Information System (INIS)

    The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R and D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics

  4. Combinatorial geometry in the plane

    CERN Document Server

    Hadwiger, Hugo; Klee, Victor

    2014-01-01

    Geared toward advanced undergraduates familiar with analysis and college geometry, this concise book discusses theorems on topics restricted to the plane such as convexity, coverings, and graphs. In addition to helping students cultivate rigorous thought, the text encourages the development of mathematical intuition and clarifies the nature of mathematical research.The two-part treatment begins with specific topics including integral distances, covering problems, point set geometry and convexity, simple paradoxes involving point sets, and pure combinatorics, among other subjects. The second pa

  5. Constructing a uniform plane-filling path in the ternary heptagrid of the hyperbolic plane

    OpenAIRE

    Maurice Margenstern

    2007-01-01

    In this paper, we distinguish two levels for the plane-filling property. We consider a simple and a strong one. In this paper, we give the construction which proves that the simple plane-filling property also holds for the hyperbolic plane. The plane-filling property was established for the Euclidean plane by J. Kari, see [2], in the strong version. We also give an application of the construction to devise a Peano curve in the hyperbolic plane.

  6. Contact Cohomology of the Projective Plane

    OpenAIRE

    Ernstr{ö}m, Lars; Kennedy, Gary

    1997-01-01

    We construct an associative ring which is a deformation of the quantum cohomology ring of the projective plane. Just as the quantum cohomology encodes the incidence characteristic numbers of rational plane curves, the contact cohomology encodes the tangency characteristic numbers.

  7. On free fermions and plane partitions

    OpenAIRE

    Foda, O.; Wheeler, M.; Zuparic, M.

    2008-01-01

    We use free fermion methods to re-derive a result of Okounkov and Reshetikhin relating charged fermions to random plane partitions, and to extend it to relate neutral fermions to strict plane partitions.

  8. On maps taking lines to plane curves

    OpenAIRE

    Petrushchenko, Vsevolod; Timorin, Vladlen

    2014-01-01

    We study cubic rational maps that take lines to plane curves. A complete description of such cubic rational maps concludes the classification of all planarizations, i.e., maps taking lines to plane curves.

  9. Description and phylogenetic position of the first abyssal solitary kamptozoan species from the Kuril-Kamchatka Trench area: Loxosomella profundorum sp. nov. (Kamptozoa: Loxosomatidae)

    Science.gov (United States)

    Borisanova, Anastasia O.; Chernyshev, Alexei V.; Neretina, Tatyana V.; Stupnikova, Alexandra N.

    2015-01-01

    One of two orders of a small phylum Kamptozoa, Solitaria, consisting of one family Loxosomatidae of about 140 species, has never been recorded deeper than 700 m. All known for the north-western Pacific loxosomatids (about 17 species) occur in shallow waters. The first abyssal solitary kamptozoan, Loxosomella profundorum sp. nov. is described herein. It was collected during the German-Russian deep-sea expedition KuramBio aboard RV Sonne in the summer of 2012 in the abyssal plain adjacent to the Kuril-Kamchatka Trench. It is the deepest finding of Kamptozoa to date. The new species was found living on the anthozoan polyp Corallimorpharia. L. profundorum sp. nov. is a largest solitary kamptozoan species, up to 4 mm in length, with a stalk of up to 3.5 mm, with 10-12 tentacles, with two conspicuous lateral papillae, and a row of glandular cells in its stalk. A preliminary molecular phylogenetic analysis based on partial 18S rDNA indicated that L. profundorum sp. nov. is a sister clade to the clade, which includes other Loxosomella and two species of Loxomitra.

  10. Geochemistry of abyssal peridotites from the super slow-spreading Southwest Indian Ridge near 65°E: Implications for magma source and seawater alteration

    Indian Academy of Sciences (India)

    Zhigang Zeng; Qiaoyun Wang; Xiaomei Wang; Shuai Chen; Xuebo Yin; Zhaoxue Li

    2012-10-01

    The geochemical characteristics of abyssal peridotite samples from one dredge station (27° 49.74′S, 65° 02.14′E, water depth 4473 m) on the super slow-spreading Southwest Indian Ridge (SWIR) near 65°E were investigated. Abyssal peridotites recovered from this site were comprised mainly of lizardite, chlorite, carbonate and magnetite with minor amounts of talc, pyroxene phenocrysts and sparse olivines. Serpentinites exhibit talc veins and major serpentine derived from serpentinization with relict olivine granuloblasts. Olivine grains in serpentinites display exsolution lamellae, indicating the occurrence of talc reduction or decompression during seawater–rock interaction. Pyroxene shows clear cleavage in two directions, with clinopyroxene or orthopyroxene exsolution lamellae. By contrast, bulk rock trace element patterns of serpentinites reveal depletion in most incompatible elements, similarly to the depleted midocean ridge basalt mantle composition, indicating that the SWIR peridotites originated from a depleted mantle source magma and have experienced partial melting. Meanwhile, Rb, Ba, U, Pb, Sr, Li anomalies and the Ce/Pb ratio suggest that these serpentinites have been strongly altered by seawater.

  11. The half plane UIPT is recurrent

    OpenAIRE

    Angel, Omer; Ray, Gourab

    2016-01-01

    We prove that the half plane version of the uniform infinite planar triangulation (UIPT) is recurrent. The key ingredients of the proof are a construction of a new full plane extension of the half plane UIPT, based on a natural decomposition of the half plane UIPT into independent layers, and an extension of previous methods for proving recurrence of weak local limits (still using circle packings).

  12. Aspects of Plane Wave (Matrix) String Dynamics

    OpenAIRE

    Blau, Matthias; O'Loughlin, Martin; Seri, Lorenzo

    2011-01-01

    We analyse two issues that arise in the context of (matrix) string theories in plane wave backgrounds, namely (1) the use of Brinkmann- versus Rosen-variables in the quantum theory for general plane waves (which we settle conclusively in favour of Brinkmann variables), and (2) the regularisation of the quantum dynamics for a certain class of singular plane waves (discussing the benefits and limitations of regularisations of the plane-wave metric itself).

  13. The Bolocam Galactic Plane Survey

    Science.gov (United States)

    Glenn, Jason; Aguirre, James; Bally, John; Battersby, Cara; Bradley, Eric Todd; Cyganowski, Claudia; Dowell, Darren; Drosback, Meredith; Dunham, Miranda K.; Evans, Neal J., II; Ginsburg, Adam; Harvey, Paul; Rosolowsky, Erik; Schlingman, Wayne; Shirley, Yancy L.; Stringfellow, Guy S.; Walawender, Josh; Williams, Jonathan

    2009-01-01

    The Bolocam Galactic Plane Survey (BGPS) is a 1.1 millimeter continuum survey of the northern Galactic Plane made with Bolocam and the Caltech Submillimeter Observatory. The coverage totals 170 square degrees, comprised of a contiguous range from -10.5 deg is less than or equal to 90.5 deg, 0.5 deg is less than or equal to b is less than or equal to 0.5 deg, with extended coverage in b in selected regions, and four targeted regions in the outer Galaxy, including: IC1396, toward the Perseus arm at l is approximately 111 deg, W3/4/5, and Gem OB1. Depths of the maps range from 30 to 60 mJy beam (sup 1). Approximately 8,400 sources were detected and the maps and source catalog have been made publicly available. Millimeter-wave thermal dust emission reveals dense regions within molecular clouds, thus the BGPS serves as a database for studies of the dense interstellar medium and star formation within the Milky Way.

  14. The INTEGRAL Galactic Plane Scanning

    CERN Document Server

    Fiocchi, Mariateresa

    2013-01-01

    After the first nine years of INTEGRAL operational life, the discovery of new sources and source types, a large fraction of which are highly transient or highly absorbed, is certainly one of the most compelling results and legacies of INTEGRAL. Frequent monitoring of the Galactic Plane in AO8 and AO9 campaigns allowed us to detect transient sources, both known and new, confirming that the gamma-ray sky is dominated by the extreme variability of different classes of objects. Regular scans of the Galactic Plane by INTEGRAL provide the most sensitive hard X-ray wide survey to date of our Galaxy, with flux limits of the order of 0.3 mCrab for an exposure time of ~2Ms. Many transient sources have been detected on a wide range of time scales (~hours to months) and identified by triggered followup observations, mainly by Swift/XRT and optical/infrared telescopes. These discoveries are very important to characterize the X-ray binary population in our Galaxy, that is necessary input for evolution studies. The transien...

  15. The UKIDSS Galactic Plane Survey

    CERN Document Server

    Lucas, P W; Longmore, A; Schröder, A C; Davis, C J; Adamson, A; Bandyopadhyay, R M; De Grijs, R; Smith, M; Gosling, A; Mitchison, S; Gaspar, A; Coe, M; Tamura, M; Parker, Q; Irwin, M; Hambly, N; Byant, J; Collins, R S; Cross, N; Evans, D W; Gonzalez-Solares, E; Hodgkin, S; Lewis, J; Read, M; Riello, M; Sutorius, E T W; Lawrence, A; Drew, J E; Dye, S

    2007-01-01

    The UKIDSS Galactic Plane Survey (GPS) is one of the five near infrared Public Legacy Surveys that are being undertaken by the UKIDSS consortium, using the Wide Field Camera on the United Kingdom Infrared Telescope. It is surveying 1868 sq.deg. of the northern and equatorial Galactic plane at Galactic latitudes -5

  16. Optimization of starshades: focal plane versus pupil plane

    CERN Document Server

    Flamary, Rémi

    2014-01-01

    We search for the best possible transmission for an external occulter coronagraph that is dedicated to the direct observation of terrestrial exoplanets. We show that better observation conditions are obtained when the flux in the focal plane is minimized in the zone in which the exoplanet is observed, instead of the total flux received by the telescope. We describe the transmission of the occulter as a sum of basis functions. For each element of the basis, we numerically computed the Fresnel diffraction at the aperture of the telescope and the complex amplitude at its focus. The basis functions are circular disks that are linearly apodized over a few centimeters (truncated cones). We complemented the numerical calculation of the Fresnel diffraction for these functions by a comparison with pure circular discs (cylinder) for which an analytical expression, based on a decomposition in Lommel series, is available. The technique of deriving the optimal transmission for a given spectral bandwidth is a classical reg...

  17. Counting plane curves of any genus

    OpenAIRE

    Caporaso, Lucia; Harris, Joe

    1996-01-01

    We obtain a recursive formula answering the following question: How many irreducible, plane curves of degree d and (geometric) genus g pass through 3d-1+g general points in the plane? The formula is proved by studying suitable degenerations of plane curves.

  18. The characteristic numbers of quartic plane curves

    OpenAIRE

    Vakil, Ravi

    1998-01-01

    The characteristic numbers of smooth plane quartics are computed using intersection theory on a component of the moduli space of stable maps. This completes the verification of Zeuthen's prediction of characteristic numbers of smooth plane curves. A short sketch of a computation of the characteristic numbers of plane cubics is also given as an illustration.

  19. Monopole Antenna with Modify Ground Plane

    OpenAIRE

    kamal raj singh rajoriya; Singhal, P.K.

    2012-01-01

    This paper presents on modified the ground plane of monopole antenna with varying the shape and length. Basically the length of ground plane of monopole antenna is equal and greater than λ/4. Here analyzed a different ground plane of monopole antenna that is provided an efficient bandwidth with sufficient return loss.

  20. Monopole Antenna with Modify Ground Plane

    Directory of Open Access Journals (Sweden)

    kamal raj singh rajoriya

    2012-06-01

    Full Text Available This paper presents on modified the ground plane of monopole antenna with varying the shape and length. Basically the length of ground plane of monopole antenna is equal and greater than λ/4. Here analyzed a different ground plane of monopole antenna that is provided an efficient bandwidth with sufficient return loss.

  1. An introduction to finite projective planes

    CERN Document Server

    Albert, Abraham Adrian

    2015-01-01

    Geared toward both beginning and advanced undergraduate and graduate students, this self-contained treatment offers an elementary approach to finite projective planes. Following a review of the basics of projective geometry, the text examines finite planes, field planes, and coordinates in an arbitrary plane. Additional topics include central collineations and the little Desargues' property, the fundamental theorem, and examples of finite non-Desarguesian planes.Virtually no knowledge or sophistication on the part of the student is assumed, and every algebraic system that arises is defined and

  2. Topological equivalence of finitely determined real analytic plane-to-plane map-germs

    OpenAIRE

    Skutlaberg, Olav

    2009-01-01

    Generic smooth plane-to-plane map germs are topologically equivalent to cones of mappings of the circle. We carry out a complete topological classification of smooth stable mappings of the circle and show how this classification leads, via the result mentioned above, to a topological classification of finitely determined real analytic plane-to-plane map germs.

  3. Messages from the Abyss

    Science.gov (United States)

    2003-10-01

    VLT Observes Infrared Flares from Black Hole at Galactic Centre [1] Summary An international team of astronomers led by researchers at the Max-Planck Institute for Extraterrestrial Physics (MPE) in Garching (Germany) [2] has discovered powerful infrared flares from the supermassive black hole at the heart of the Milky Way . The signals, rapidly flickering on a scale of minutes, must come from hot gas falling into the black hole, just before it disappears below the "event horizon" of the monster. The new observations strongly suggest that the Galactic Centre black hole rotates rapidly . Never before have scientists been able to study phenomena in the immediate neighbourhood of a black hole in such a detail. The new result is based on observations obtained with the NACO Adaptive Optics instrument on the 8.2-m VLT YEPUN telescope and is published in this week's edition of the research journal Nature. PR Photo 29a/03 : A powerful flare from the black hole at the galactic centre. PR Photo 29b/03 : Light curve of the flare . PR Video 01/03 : A powerful flare from the black hole at the galactic centre . Flashes of light from disappearing matter ESO PR Photo 29a/03 ESO PR Photo 29a/03 [Preview - JPEG: 650 x 400 pix - 118k [Normal - JPEG: 1300 x 800 pix - 370k] ESO PR Video Clip 01/03 [MPEG] ESO PR Video Clip 01/03 [MPEG Video; 29X k] Captions : PR Photo 29a/03 and PR Video Clip 01/03 show the detection of a powerful flare from the centre of the Milky Way galaxy. These and other adaptive optics (AO) images (with resolution 0.040 arcsec in the near-infrared H-band at wavelength 1.65 µm) of the central region of the Milky Way were obtained with the NACO imager on the 8.2-m VLT YEPUN telescope at the ESO Paranal Observatory on May 9, 2003. The image covers a sky area of about 1 x 1 arcsec, corresponding to about 45 light-days at the distance of the Galactic Centre. The time (in minutes from the beginning of the data set at 6h59m24s (UT) on May 9, 2003) is shown at the upper right of each image. North is up and East to the left. The position of the 15-year orbiting star S2 (cf. ESO Press Release 17/02 ) is marked by a cross and the astrometric location of the black hole is indicated by a circle. The scene was the usual one in the VLT Control Room at the Paranal Observatory in the early morning of May 9, 2003. Groups of astronomers from different nations were sitting in front of the computer screens, pointing the four giant telescopes in different directions and recording the sparse photons from the remotest corners of the Universe. There were the usual brief exchanges of information, numbers, wavelengths, strange acronyms, but then suddenly something happened at the YEPUN desk.... " What is that star doing there? " exclaimed Rainer Schödel , one of the MPE scientists in the team working with the NACO Adaptive Optics instrument [3] that delivers razor-sharp images. He and Reinhard Genzel, leader of the team and MPE Director, were observing the Milky Way Centre, when they saw the "new" object on the screen in front of them. The astronomers were puzzled and then became excited - something unusual must be going on, there at the centre of our galaxy! And then, a few minutes later, the "star" disappeared from view. Now the scientists had little doubt - they had just witnessed, for the first time, a powerful near-infrared flare from exactly the direction of the supermassive black hole at the heart of the Milky Way , cf. PR Photo 29a/03 and PR Video Clip 01/03 . " We had been looking for infrared emission from that black hole for more than a decade " recalls another team member, Andreas Eckart of the Cologne University. " We were certain that the black hole must be accreting matter from time to time. As this matter falls towards the surface of the black hole, it gets hotter and hotter and starts emitting infrared radiation ". But no such infrared radiation had been seen until that night at the VLT. This was the wonderful moment of breakthrough. Never before had anybody witnessed the last "scream" from matter in the deadly grip of a black hole, about to pass the point of no return towards an unknown fate. At the border ESO PR Photo 29b/03 ESO PR Photo 29b/03 [Preview - JPEG: 400 x 516 pix - 87k [Normal - JPEG: 800 x 1032 pix - 219k] Captions : PR Photo 29b/03 displays the "light curve" of a light flare from the galactic centre, as observed in the K-band (wavelength 2.2 µm) on June 16, 2003. This and a second flare discovered about 24 hours earlier show variability on a time scale of a few minutes and appear to show larger variations (arrows) with a 17-minute periodicity. The rapid variability implies that the infrared emission comes from just outside (the event horizon of) the black hole. If the periodicity is a fundamental property of the motion of gas orbiting the black hole, the Galactic Centre black hole must rotate with about half the maximum spin rate allowed by General Relativity. The present observations thus probe the space-time structure in the immediate vicinity of that event horizon. A careful analysis of the new observational data, reported in this week's issue of the Nature magazine, has revealed that the infrared emission originates from within a few thousandths of an arcsecond [4] from the position of the black hole (corresponding to a distance of a few light-hours) and that it varies on time scales of minutes ( PR Photo 29b/03 ). This proves that the infrared signals must come from just outside the so-called "event horizon" of the black hole, that is the "surface of no return" from which even light cannot escape. The rapid variability seen in all data obtained by the VLT clearly indicates that the region around this horizon must have chaotic properties - very much like those seen in thunderstorms or solar flares [5]. " Our data give us unprecedented information about what happens just outside the event horizon and let us test the predictions of General Relativity " explains Daniel Rouan , a team member from Paris-Meudon Observatory. " The most striking result is an apparent 17-minute periodicity in the light curves of two of the detected flares. If this periodicity is caused by the motion of gas orbiting the black hole, the inevitable conclusion is that the black hole must be rotating rapidly ". Reinhard Genzel is very pleased: " This is a major breakthrough. We know from theory that a black hole can only have mass, spin and electrical charge. Last year we were able to unambiguously prove the existence and determine the mass of the Galactic Centre black hole ( ESO Press Release 17/02 ). If our assumption is correct that the periodicity is the fundamental orbital time of the accreting gas, we now have also measured its spin for the first time . And that turns out to be about half of the maximum spin that General Relativity allows ". He adds: " Now the era of observational black hole physics has truly begun !" More information The results described in this ESO press release are presented in a report published today in the research journal "Nature" ("Near-IR Flares from Accreting Gas around the Supermassive Black Hole in the Galactic Centre", by Reinhard Genzel and co-authors).

  4. ABYSSES OF FIRE

    Directory of Open Access Journals (Sweden)

    Rafael Santana

    2015-11-01

    Full Text Available The aim of this paper is to think the genesis of the poetry in the artistic universe of Mário de Sá-Carneiro, a poet who undertakes literary criticism from within his own writings while reckoning with the specificities of art. Following the path of some of the iconic figures of modern times, such as Baudelaire, Rimbaud and Mallarmé, Sá-Carneiro inscribes his poetry in a tradition of a whole lineage of poets for whom writing is above all a hand-to-hand with language.

  5. Peering into the abyss

    International Nuclear Information System (INIS)

    The multi-continent detections of the neutrinos from the core of SN 1987A open a new chapter in high energy astrophysics. For the first time, we have penetrated the supernova ejecta and glimpsed at the violent convulsions that attend stellar collapse and the birth of a neutron star. The neutrino emissions are the only good diagnostic of implosion physics, and the new data allow to test supernova theories in a unique way. The author compares the theory developed over the last 20 years with these observations to extract what information there is in these epochal detections

  6. Radioactivity in the galactic plane

    Science.gov (United States)

    Walraven, G. D.; Haymes, R. C.

    1976-01-01

    The paper reports the detection of a large concentration of interstellar radioactivity during balloon-altitude measurements of gamma-ray energy spectra in the band between 0.02 and 12.27 MeV from galactic and extragalactic sources. Enhanced counting rates were observed in three directions towards the plane of the Galaxy; a power-law energy spectrum is computed for one of these directions (designated B 10). A large statistical deviation from the power law in a 1.0-FWHM interval centered near 1.16 MeV is discussed, and the existence of a nuclear gamma-ray line at 1.15 MeV in B 10 is postulated. It is suggested that Ca-44, which emits gamma radiation at 1.156 MeV following the decay of radioactive Sc-44, is a likely candidate for this line, noting that Sc-44 arises from Ti-44 according to explosive models of supernova nucleosynthesis. The 1.16-MeV line flux inferred from the present data is shown to equal the predicted flux for a supernova at a distance of approximately 3 kpc and an age not exceeding about 100 years.

  7. Focal Plane Instrumentation of VERITAS

    CERN Document Server

    Nagai, T; Sleege, G; Petry, D

    2007-01-01

    VERITAS is a new atmospheric Cherenkov imaging telescope array to detect very high energy gamma rays above 100 GeV. The array is located in southern Arizona, USA, at an altitude of 1268m above sea level. The array consists of four 12-m telescopes of Davies-Cotton design and structurally resembling the Whipple 10-m telescope. The four focal plane instruments are equipped with high-resolution (499 pixels) fast photo-multiplier-tube (PMT) cameras covering a 3.5 degree field of view with 0.15 degree pixel separation. Light concentrators reduce the dead-space between PMTs to 25% and shield the PMTs from ambient light. The PMTs are connected to high-speed preamplifiers allowing operation at modest anode current and giving good single photoelectron peaks in situ. Electronics in the focus box provides real-time monitoring of the anode currents for each pixel and ambient environmental conditions. A charge injection subsystem installed in the focus box allows daytime testing of the trigger and data acquisition system b...

  8. Duel-Plane Optical Disdrometer

    Science.gov (United States)

    Winsky, B. E.; Eichinger, W. E.

    2011-12-01

    Acquiring better drop-size distributions of rainfall will improve our understanding of the spatial and temporal variability of rainfall. In order to fully capture the spatial and temporal variability of rainfall, a robust, calibration free, low-cost instrument that provides an accurate drop-size distribution is required. Therefore, The University of Iowa Lidar Group has developed and built a new duel-plane optical disdrometer that meets these criteria. Two sheets of laser light, vertically spaced by 1 cm are produced by two 670nm laser beams passing through a collecting lens and culminating lens, respectively. The two sheets of laser light then pass through a convex lens located 20 cm from the lasers that focuses the light on a photo detector. A computer reads in and stores the voltages at 10 kHz. The velocity, diameter, shape and drop-size distribution of raindrops are extracted from the voltage measurements. Rainfall data collected in Iowa City, IA tested our disdrometer's robustness and accuracy of providing drop-size distributions. Our distrometer is advantageous because it is simple, low-cost, and requires no calibration.

  9. Periodical plane puzzles with numbers

    CERN Document Server

    Rezende, Jorge

    2011-01-01

    Consider a periodical (in two independent directions) tiling of the plane with polygons (faces). In this article we shall only give examples using squares, regular hexagons, equilateral triangles and parallelograms ("unions" of two equilateral triangles). We shall call some "multiple" of the fundamental region "the board". We naturally identify pairs of corresponding edges of the the board. Figures 9 and 19-29, in this article, show different boards. The "border" of the board is represented by a yellow thick line, unless part of it or all of it is the edge of a face. The board is tiled by a finite number of polygons. Construct polygonal plates in the same number, shape and size as the polygons of the board. Adjacent to each side of each plate draw a number, or two numbers, like it is shown in Figures 1 and 18-29. Figure 1 shows the obvious possibility of having plates with simple drawings, coloured drawings, etc. Now the game is to put the plates over the board polygons in such a way that the numbers near eac...

  10. Polychaete composition from the abyssal plain adjacent to the Kuril-Kamchatka Trench with the description of a new species of Sphaerephesia (Polychaeta: Sphaerodoridae)

    Science.gov (United States)

    Alalykina, Inna L.

    2015-01-01

    During the KuramBio expedition, the abyssal plain adjacent to the Kuril-Kamchatka Trench was sampled in July-August 2012. More than 5200 individuals of Polychaeta belonging to 38 families, 108 genera and about 144 species were found. Six genera have been reported for the Northwest Pacific for the first time. About 50% of the collected polychaete species are considered as new to science. One of these, Sphaerephesia lesliae sp. n., is described herein. The detailed description of the new species is presented and its differences from similar species are shown. This eighth species of the genus is characterized by the presence of macrotubercles with two paired terminal papillae. The genus Sphaerephesia Fauchald, 1972 is newly recorded in the Northwest Pacific. An updated key to the species of the genus Sphaerephesia is provided.

  11. A new species of Comephoronema (Nematoda: Cystidicolidae) from the stomach of the abyssal halosaur Halosauropsis macrochir (Teleostei) from the Mid-Atlantic Ridge.

    Science.gov (United States)

    Moravec, Frantisek; Klimpel, Sven

    2007-08-01

    A new species of parasitic nematode Comephoronema macrochiri n. sp. (Cystidicolidae), is described from the stomach of the marine deep-sea fish Halosauropsis macrochir (abyssal halosaur) from the Mid-Atlantic Ridge (MAR). The new species, studied with both light and scanning electron microscopy, is characterized mainly by 6 pairs of preanal papillae, by which it principally differs from members of Ascarophis; the spicules are 297-375 microm and 99-120 microm long and fully developed eggs possess 2 long filaments on 1 pole. Rhabdochona beatriceinsleyae is transferred to Comephoronema as C. beatriceinsleyae (Holloway and Klewer, 1969) n. comb. Comephoronema macrochiri differs from all other congeners mainly in having eggs with filaments on 1 pole only, and from individual species by some additional features such as the number of preanal papillae, the shape of pseudolabial projections, and the body and organ measurements. PMID:17918373

  12. Signal processing for plane wave actuators

    OpenAIRE

    T. Corbach; Holters, M.; U. Zölzer

    2010-01-01

    Plane wave actuators without an enclosure per se have a forward and backward radiation. The backward radiation is unwanted in many applications when a single direction radiation is desired. To avoid the disadvantages of an enclosure a system is proposed, which provides a high suppression of the unwanted backward radiation using a pair of plane wave actuators. This is achieved by adapted input signal filters. The influences of the second plane wave actuator to the forward rad...

  13. Structural iron (II of basaltic glass as an energy source for Zetaproteobacteria in an abyssal plain environment, off the Mid Atlantic Ridge

    Directory of Open Access Journals (Sweden)

    Pauline Audrey Henri

    2016-01-01

    Full Text Available To explore the capability of basaltic glass to support the growth of chemosynthetic microorganisms, complementary in situ and in vitro colonization experiments were performed. Microbial colonizers containing synthetic tholeitic basaltic glasses, either enriched in reduced or oxidized iron, were deployed off-axis from the Mid Atlantic Ridge on surface sediments of the abyssal plain (35°N; 29°W. In situ microbial colonization was assessed by sequencing of the 16S rRNA gene and basaltic glass alteration was characterized using Scanning Electron Microscopy, micro-X-ray Absorption Near Edge Structure at the Fe-K-edge and Raman microspectroscopy. The colonized surface of the reduced basaltic glass was covered by a rind of alteration made of iron-oxides trapped in a palagonite-like structure with thicknesses up to 150 µm. The relative abundance of the associated microbial community was dominated (39% of all reads by a single operational taxonomic unit (OTU that shared 92% identity with the iron-oxidizer Mariprofundus ferrooxydans PV-1. Conversely, the oxidized basaltic glass showed the absence of iron-oxides enriched surface deposits and correspondingly there was a lack of known iron-oxidizing bacteria in the inventoried diversity. In vitro, a similar reduced basaltic glass was incubated in artificial seawater with a pure culture of the iron-oxidizing M. ferrooxydans DIS-1 for 2 weeks, without any additional nutrients or minerals. Confocal Laser Scanning Microscopy revealed that the glass surface was covered by twisted stalks characteristic of this iron-oxidizing Zetaproteobacteria. This result supported findings of the in situ experiments indicating that the Fe(II present in the basalt was the energy source for the growth of representatives of Zetaproteobacteria in both the abyssal plain and the in vitro experiment. In accordance, the surface alteration rind observed on the reduced basaltic glass incubated in situ could at least partly result from

  14. Cross-basin heterogeneity in lanternfish (family Myctophidae) assemblages and isotopic niches (δ13C and δ15N) in the southern Tasman Sea abyssal basin

    Science.gov (United States)

    Flynn, A. J.; Kloser, R. J.

    2012-11-01

    A cross-basin (longitudinal) study of lanternfishes in the southern Tasman Sea abyssal basin during the austral winter of 2008 and 2009 found that mean biomass in the Western sector was higher than that in the Eastern sector, corresponding with cross-basin patterns in oceanographic heterogeneity and productivity. Dominant species over the abyssal basin differed from those previously recorded over the neighbouring continental slope. Vertical biomass profiles indicated diffuse night-time distributions in the Central sector and extensive diel vertical migrations in the Eastern sector. In the Western sector, macrocrustacean δ13C values were significantly higher, and δ15N significantly lower, than those in the Eastern sector. The results indicate a cross-basin difference in the primary productivity environment and 15N enrichment at the base of the foodweb. The cross-basin pattern in lanternfish δ15N values mirrored that for macrocrustaceans and was not correlated with standard length. Lanternfish δ13C values did not differ between sectors, but there were depth-wise differences, with values in the shallowest stratum (0-200 m) significantly higher than those in the deepest stratum (800-1000 m). Calculated trophic levels (TLs) of lanternfishes spanned the third trophic level and marked niche segregation was evident in the Eastern (mean TL 3.0-3.9) and Central (mean TL 2.5-3.6) sectors. Together, the results suggest that the Eastern and Western sectors are distinct sub-basin scale pelagic habitats, with implications for ecosystem modelling and future monitoring.

  15. Bioturbation, geochemistry and geotechnics of sediments affected by the oxygen minimum zone on the Oman continental slope and abyssal plain, Arabian Sea

    Science.gov (United States)

    Meadows, Azra; Meadows, Peter S.; West, Fraser J. C.; Murray, John M. H.

    2000-01-01

    We investigate the way the oxygen minimum zone (OMZ) alters interactions between bioturbation and sediment geochemistry, and geotechnical properties. Sediments are compared within and below the OMZ on the Oman continental slope and adjacent abyssal plain during the post monsoonal autumn season. Quantitative measurements were made of Eh and pH, of total organic matter (TOM) and carbonate, of water content and shear strength, and of bioturbation structures in vertical profiles of subcores taken from spade-box core samples. The OMZ stations had distinctively low redox conditions and high carbonate content, and different geotechnical properties and different bioturbation structures than stations below the OMZ on the abyssal plain. These differences are related to the degree of anoxia and to water depth. Within the OMZ, Eh, pH and carbonate increased with water depth, and TOM and water content decreased. We also noted the presence of subsurface sediment heterogeneity on the continental slope within the OMZ. In the OMZ, Eh, water content and bioturbation decreased with increasing sediment depth. There was a slight decrease in pH in the top 5 cm at all stations. Shear strength nearly always increased with increasing sediment depth. At each water depth correlations show down-core trends in these parameters, while across all water depths correlations were significant at deeper sediment depths (20-30 cm). An Eh-pH diagram identified two water-depth groupings: 391-1008 and 1265-3396 m. Cluster analysis showed the upper and lower sediment depths form separate clusters, the break occurring at 4-7.5 cm; while there are also distinct clusters related to water depth. We relate our results to bottom-water oxygen concentrations reported by other investigators, and to regional-scale geochemical processes.

  16. Nanostructured carbon films with oriented graphitic planes

    International Nuclear Information System (INIS)

    Nanostructured carbon films with oriented graphitic planes can be deposited by applying energetic carbon bombardment. The present work shows the possibility of structuring graphitic planes perpendicular to the substrate in following two distinct ways: (i) applying sufficiently large carbon energies for deposition at room temperature (E>10 keV), (ii) utilizing much lower energies for deposition at elevated substrate temperatures (T>200 deg. C). High resolution transmission electron microscopy is used to probe the graphitic planes. The alignment achieved at elevated temperatures does not depend on the deposition angle. The data provides insight into the mechanisms leading to the growth of oriented graphitic planes under different conditions.

  17. Enumeration of Cylindric Plane Partitions - part I

    CERN Document Server

    Langer, Robin

    2012-01-01

    Cylindric plane partitions may be thought of as a natural generalization of reverse plane partitions. A generating series for the enumeration of cylindric plane partitions was recently given by Borodin. The first result of this paper is a $(q,t)$-analog of Borodin's identity which extends previous work by Okada in the reverse plane partition case. Our proof uses commutation relations for $(q,t)$-vertex operators acting on Macdonald polynomials as given by Garsia, Haiman and Tesla. The second result of this paper is an explicit combinatorial interpreation of the $(q,t)$-Macdonald weight in terms of a non-intersecting lattice path model on the cylinder.

  18. Large Format Uncooled Focal Plane Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Black Forest Engineering has identified innovative modifications in uncooled focal plane array (UFPA) architecture and processing that allows development of large...

  19. Slipping and Rolling on an Inclined Plane

    Science.gov (United States)

    Aghamohammadi, Cina; Aghamohammadi, Amir

    2011-01-01

    In the first part of the paper, using a direct calculation two-dimensional motion of a particle sliding on an inclined plane is investigated for general values of friction coefficient ([mu]). A parametric equation for the trajectory of the particle is also obtained. In the second part of the paper, the motion of a sphere on the inclined plane is…

  20. Corner diffraction coefficients for the quarter plane

    DEFF Research Database (Denmark)

    Hansen, Thorkild B.

    1991-01-01

    The current near a right-angled corner on a perfectly conducting flat scatterer illuminated by a plane wave is expressed as a sum of three currents. The first is the physical optics current, which describes the surface effect. The second is the fringe wave current, which is found from the half-plane...

  1. Criteria for singularities of smooth maps from the plane into the plane and its applications

    OpenAIRE

    Saji, Kentaro

    2009-01-01

    We shall give useful criteria of lips, beaks and swallowtail singularities of smooth map from the plane into the plane. As an application of criteria, we will discuss the singularities of Cauchy problem of single conservation law.

  2. Slipping and rolling on an inclined plane

    Energy Technology Data Exchange (ETDEWEB)

    Aghamohammadi, Cina [Department of Electrical Engineering, Sharif University of Technology, PO Box 11365-11155, Tehran (Iran, Islamic Republic of); Aghamohammadi, Amir, E-mail: mohamadi@alzahra.ac.ir [Department of Physics, Alzahra University, Tehran 19938-91176 (Iran, Islamic Republic of)

    2011-07-15

    In the first part of the paper, using a direct calculation two-dimensional motion of a particle sliding on an inclined plane is investigated for general values of friction coefficient ({mu}). A parametric equation for the trajectory of the particle is also obtained. In the second part of the paper, the motion of a sphere on the inclined plane is studied. It is shown that the evolution equation for the contact point of a sliding sphere is similar to that of a point particle sliding on an inclined plane whose friction coefficient is 7/2 {mu}. If {mu} > 2/7 tan {theta}, for any arbitrary initial velocity and angular velocity, the sphere will roll on the inclined plane after some finite time. In other cases, it will slip on the inclined plane. In the case of rolling, the centre of the sphere moves on a parabola. Finally the velocity and angular velocity of the sphere are exactly computed.

  3. Unique 16S rRNA sequences of Eurythenes gryllus (Crustacea: Amphipoda: Lysianassidae) from the Gulf of Mexico abyssal plain Secuencias únicas 16SrRNA de Eurythenes gryllus (Crustacea: Amphipoda: Lysianassidae) de la planicie abisal del Golfo de México

    OpenAIRE

    Elva Escobar-Briones; Eduardo Nájera-Hillman; Fernando Álvarez

    2010-01-01

    Amphipods of the species Eurythenes gryllus were collected at 2 locations on the abyssal plain (~3 400 m) of the Gulf of Mexico in order to test whether or not these scavenger amphipods are isolated in this peripheral sea or show connectivity by their predominant swimming behavior, moving horizontally along the abyssal water masses in the region. Partial sequences of the mitochondrial 16S rRNA gene from 2 individuals of E. gryllus were determined and showed small differences when compared to ...

  4. Slip patterns and preferred dislocation boundary planes

    DEFF Research Database (Denmark)

    Winther, G.

    2003-01-01

    The planes of deformation induced extended planar dislocation boundaries are analysed in two different co-ordinate systems, namely the macroscopic system defined by the deformation axes and the crystallographic system given by the crystallographic lattice. The analysis covers single and polycryst......The planes of deformation induced extended planar dislocation boundaries are analysed in two different co-ordinate systems, namely the macroscopic system defined by the deformation axes and the crystallographic system given by the crystallographic lattice. The analysis covers single and...... polycrystals of fcc metals in three deformation modes (rolling, tension and torsion). In the macroscopic system, boundaries lie close to the macroscopically most stressed planes. In the crystallographic system, the boundary plane depends on the grain/crystal orientation. The boundary planes in both co......-ordinate systems are rationalised based on the slip. The more the slip is concentrated on a slip plane, the closer the boundaries lie to this. The macroscopic preference arises from the macroscopic directionality of the slip. The established relations are applied to (a) prediction of boundary planes from slip...

  5. Knot theory of complex plane curves

    OpenAIRE

    Rudolph, Lee

    2004-01-01

    The primary objects of study in the ``knot theory of complex plane curves'' are C-links: links (or knots) cut out of a 3-sphere in the complex plane by complex plane transverse and totally tangential. Transverse C-links are naturally oriented. There are many natural classes of examples: links of singularities; links at infinity; links of divides, free divides, tree divides, and graph divides; and--most generally--quasipositive links. Totally tangential C-links are unoriented but naturally fra...

  6. Analysis of Switching Noise on Power Planes

    Directory of Open Access Journals (Sweden)

    M. Ž. Stojilović

    2009-11-01

    Full Text Available Power delivery networks (PDNs in modern printed circuit boards (PCBs are usually realized using power planes. Since the planes have very low inductance, it is usually believed that such PDNs have the smallest amount of switching noise. However, in reality, the power planes can resonate. The noise at resonant frequencies can be significant and it deteriorates the PDN performance. One of the classical methods for decreasing the noise is bypassing. This paper investigates the behavior of a typical PDN and the effect that real SMD bypass capacitors produce when attached to it.

  7. Malfatti's problem on the hyperbolic plane

    CERN Document Server

    Horváth, Ákos G

    2012-01-01

    More than two centuries ago Malfatti raised and solved the following problem called by Malfatti's construction problem: In a triangle describe three small circles, each of them touching the other two, and also two sides of the triangle. Interesting fact that nobody investigated this problem on the hyperbolic plane, while the case of the sphere were solved at once. We now compensate for this shortage and solve the following exercise: Determine three cycles of the hyperbolic plane, each of them touching the two others, and also two of three given cycles of the hyperbolic plane. We also give a proof of the hyperbolic version of Malfatti's marble problem.

  8. Large Format Uncooled Focal Plane Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Uncooled focal plane arrays have improved dramatically and array sizes of 320x240 elements in a 50-?m pitch are commercially available at affordable cost. Black...

  9. Titanium Heat Pipe Thermal Plane Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermacore Inc. proposes an innovative titanium heat pipe thermal plane for passive thermal control of individual cells within a fuel cell stack. The proposed...

  10. Strings in plane-fronted gravitational waves

    OpenAIRE

    Duval, C.; Horvath, Z.; Horvathy, P. A.

    2006-01-01

    Brinkmann's plane-fronted gravitational waves with parallel rays --~shortly pp-waves~-- are shown to provide, under suitable conditions, exact string vacua at all orders of the sigma-model perturbation expansion.

  11. Parallels plane projection and its geometric features

    Institute of Scientific and Technical Information of China (English)

    ZHOU ChengHu; MA Ting; YANG Liao; QIN Biao

    2007-01-01

    A new equivalent map projection called the parallels plane projection is proposed in this paper. The transverse axis of the parallels plane projection is the expansion of the equator and its vertical axis equals half the length of the central meridian. On the parallels plane projection, meridians are projected as sine curves and parallels are a series of straight, parallel lines. No distortion of length occurs along the central meridian or on any parallels of this projection. Angular distortion and the proportion of length along meridians (except the central meridian) introduced by the projection transformation increase with increasing longitude and latitude. A potential application of the parallels plane projection is that it can provide an efficient projection transformation for global discrete grid systems.

  12. In-focal-plane SQUID multiplexer

    International Nuclear Information System (INIS)

    Superconducting quantum interference device (SQUID) multiplexers make it possible to build arrays of thousands of microcalorimeters and bolometers based on superconducting transition-edge sensors (TES) with a manageable number of readout channels. Previous to this work, TES arrays were multiplexed by extracting leads from each pixel to multiplexer filter and switching elements outside of the focal plane. As the number of pixels is increased in a close-packed array, it becomes difficult to route the leads to the multiplexer. We report on the development of an in-focal-plane SQUID multiplexer to solve this problem. In this circuit, the filter and switching elements associated with each pixel fit within the pixel area so that signals are multiplexed before being extracted from the focal plane. This in-focal-plane architecture will first be used in the SCUBA-2 instrument at the James Clerk Maxwell Telescope in 2006

  13. Titanium Heat Pipe Thermal Plane Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the Phase II program is to complete the development of the titanium heat pipe thermal plane and establish all necessary steps for production of...

  14. Causal inheritance in plane wave quotients

    International Nuclear Information System (INIS)

    We investigate the appearance of closed timelike curves in quotients of plane waves along spacelike isometries. First we formulate a necessary and sufficient condition for a quotient of a general spacetime to preserve stable causality. We explicitly show that the plane waves are stably causal; in passing, we observe that some pp-waves are not even distinguishing. We then consider the classification of all quotients of the maximally supersymmetric ten-dimensional plane wave under a spacelike isometry, and show that the quotient will lead to closed timelike curves iff the isometry involves a translation along the u direction. The appearance of these closed timelike curves is thus connected to the special properties of the light cones in plane wave spacetimes. We show that all other quotients preserve stable causality

  15. Causal inheritence in plane wave quotients

    Energy Technology Data Exchange (ETDEWEB)

    Hubeny, Veronika E.; Rangamani, Mukund; Ross, Simon F.

    2003-11-24

    We investigate the appearance of closed timelike curves in quotients of plane waves along spacelike isometries. First we formulate a necessary and sufficient condition for a quotient of a general spacetime to preserve stable causality. We explicitly show that the plane waves are stably causal; in passing, we observe that some pp-waves are not even distinguishing. We then consider the classification of all quotients of the maximally supersymmetric ten-dimensional plane wave under a spacelike isometry, and show that the quotient will lead to closed timelike curves iff the isometry involves a translation along the u direction. The appearance of these closed timelike curves is thus connected to the special properties of the light cones in plane wave spacetimes. We show that all other quotients preserve stable causality.

  16. Asymptotically Plane Wave Spacetimes and their Actions

    OpenAIRE

    Witt, Julian Le; Ross, Simon F.

    2008-01-01

    We propose a definition of asymptotically plane wave spacetimes in vacuum gravity in terms of the asymptotic falloff of the metric, and discuss the relation to previously constructed exact solutions. We construct a well-behaved action principle for such spacetimes, using the formalism developed by Mann and Marolf. We show that this action is finite on-shell and that the variational principle is well-defined for solutions of vacuum gravity satisfying our asymptotically plane wave falloff condi...

  17. Proof of Polyakov conjecture on supercomplex plane

    International Nuclear Information System (INIS)

    Using Neumann series, we solve iteratively SBE to arbitrary order. Then applying this, we compute the energy momentum tensor and n points functions for generic n starting from WZP action on the supercomplex plane. We solve the superconformal Ward identity and we show that the iterative solution to arbitrary order is resumed by WZP action. This proves the Polyakov conjecture on supercomplex plane. (author). 8 refs

  18. Deep plane facelifting for facial rejuvenation.

    Science.gov (United States)

    Gordon, Neil; Adam, Stewart

    2014-08-01

    The purpose of this article is to provide the facial plastic surgeon with anatomical and embryologic evidence to support the use of the deep plane technique for optimal treatment of facial aging. A detailed description of the procedure is provided to allow safe and consistent performance. Insights into anatomical landmarks, technical nuances, and alternative approaches for facial variations are presented. The following points will be further elucidated in the article. The platysma muscle/submuscular aponeurotic system/galea are the continuous superficial cervical fascia encompassing the majority of facial fat, and this superficial soft tissue envelope is poorly anchored to the face. The deep cervical fascia binds the structural aspects of the face and covers the facial nerve and buccal fat pad. Facial aging is mainly due to gravity's long-term effects on the superficial soft tissue envelope, with more subtle effects on the deeper structural compartments. The deep plane is the embryologic cleavage plane between these fascial layers, and is the logical place for facial dissection. The deep plane allows access to the buccal fat pad for treatment of jowling. Soft tissue mobilization is maximized in deep plane dissections and requires careful hairline planning. Flap advancement creates tension only at the fascia level allowing natural, tension-free skin closure, and long-lasting outcomes. The deep plane advancement flap is well vascularized and resistant to complications. PMID:25076447

  19. Galaxy Evolution Explorer (GALEX): Galactic Plane Survey

    Science.gov (United States)

    Lemley, Cameron; Mohammed, Steven; Schiminovich, David; Tam, Benjamin; Seibert, Mark; Martin, Christopher D.; GALEX Science Team

    2015-01-01

    The Galaxy Evolution Explorer (GALEX) completed its survey of the Galactic plane in the near-ultraviolet during 2012. Although preliminary data were released shortly after the completion of the survey, the full dataset was reanalyzed during 2014 using refined attitude correction techniques that yield angular resolution-limited images. The GALEX Galactic plane survey includes more than 75% of the sky between 10 > b > -10 degrees. The initial photon dataset contains about 400 individual scans, each of which is a vertical slice of the Galactic plane. Each slice spans 1500-1700 seconds, during which the 1.24 degree diameter field of view performed a double-pass sweep across the Galactic plane. The Galactic Plane survey was the only time this non-standard, high scan rate acquisition mode was exercised during the mission, and required specialized processing and astrometric refinement to produce high quality sky maps. We present the first high-resolution map of the Galactic plane in the near-ultraviolet as well as a catalogue of thousands of sources for follow-up with HST. This work was partially supported by the Keck Institute for Space Studies.

  20. Counting Plane Graphs: Flippability and its Applications

    CERN Document Server

    Hoffmann, Michael; Sheffer, Adam; Tóth, Csaba D; Welzl, Emo

    2010-01-01

    We generalize the notions of flippable and simultaneously-flippable edges in a triangulation of a set S of points in the plane, into so called pseudo simultaneously-flippable edges. Such edges are related to the notion of convex decompositions spanned by S. We derive a worst-case tight lower bound on the number of pseudo simultaneously-flippable edges in any triangulation, and use this bound to obtain upper bounds for the maximal number of several types of plane graphs that can be embedded (with crossing-free straight edges) on a fixed set of N points in the plane. More specifically, denoting by tr(N)<30^N$ the maximum possible number of triangulations of a set of N points in the plane, we show that every set of N points in the plane can have at most 6.9283^N * tr(N) < 207.85^N plane graphs, O(4.8895^N) * tr(N) = O(146.69^N) spanning trees, and O(5.4723^N) * tr(N) = O(164.17^N) forests (that is, cycle-free graphs). We also obtain upper bounds for the number of crossing-free straight-edge graphs with at ...

  1. An information-theoretic approach to designing the plane spacing for multifocal plane microscopy

    OpenAIRE

    Tahmasbi, Amir; Ram, Sripad; Chao, Jerry; Abraham, Anish V.; Ward, E Sally; Ober, Raimund J.

    2015-01-01

    Multifocal plane microscopy (MUM) is a 3D imaging modality which enables the localization and tracking of single molecules at high spatial and temporal resolution by simultaneously imaging distinct focal planes within the sample. MUM overcomes the depth discrimination problem of conventional microscopy and allows high accuracy localization of a single molecule in 3D along the z-axis. An important question in the design of MUM experiments concerns the appropriate number of focal planes and the...

  2. An account of the Ischnomesidae (Peracarida, Isopoda) from the Kuril-Kamchatka Trench and abyssal plain (Northwest Pacific) with the description of two new species

    Science.gov (United States)

    Brandt, Angelika; Kristin Stüven, Jana; Caurant, Cyril; Oskar Elsner, Nikolaus

    2015-01-01

    During the German-Russian expedition KuramBio (Kuril-Kamchatka Biodiversity Studies) from board of the RV Sonne to the Kuril-Kamchatka Trench and adjacent abyssal plain, benthic samples were taken by means of a camera-epibenthic sledge. Amongst one of the most diverse macrobenthic taxa, the Isopoda (Crustacea, Malacostraca), Ischnomesidae were the fifth most abundant isopod family in the Kuril-Kamchatka area and were sampled with 24 species from 5 genera in 21 hauls at 12 stations. Fortimesus occurs most frequently in the samples (36% of all Ischnomesidae sampled), followed by Stylomesus (26%), Heteromesus (23%), Ischnomesus (10%) and Gracilimesus (4%). Number of ischnomesid individuals is highest at station 10-12 with 35 specimens, followed by station 12-4 (30 ind.), station 6-12 (29 ind.), station 9-9 (28), and station 1-11 (24). At station 4-3 only 1 specimen was found. A key to all genera of Ischnomesidae is provided. Two new species from two genera: StylomesusWolff, 1956 and FortimesusKavanagh and Wilson, 2007 are described from the KuramBio material. Stylomesus malyutinae sp. nov. is distinguished by the smooth body surface, the shape of pleotelson and the length of uropods from other species of the genus from the Northwest Pacific Ocean. Fortimesus trispiculum sp. nov. is characterised by anterolateral projections of pereonites 1-3 which are forming an angle of about 45° with the longitudinal body axis decreasing in length from anterior to posterior.

  3. Classification of plane curves with infinitely many Galois points

    OpenAIRE

    Fukasawa, Satoru

    2011-01-01

    For a plane curve, a point in the projective plane is said to be Galois when the point projection induces a Galois extension of function fields. We completely classify plane curves with infinitely many outer Galois points.

  4. Computed tomography of peripancreatic fat planes

    Energy Technology Data Exchange (ETDEWEB)

    Wittich, G.R.; Van Sonnenberg, E.; Willson, S.A.; Tobin, R.S.; Cubberley, D.A.; Marx, M.Q.

    1987-11-01

    Obliteration of peripancreatic fat planes usually is considered an indicator of peripancreatic tumour infiltration in the presence of a malignant mass, or of inflammation of peripancreatic tissues in patients with pancreatitis. However, absence of peripancreatic fat planes also may be found in patients without evidence of pancreatic disease. Hence, CT scans of 125 patients without clinical or computed tomographic evidence of pancreatic disease were evaluated to assess normal variations in the anatomy of the pancreas and its relation to surrounding vessels and bowel loops. The fat plane separating the superior mesenteric artery from the pancreas was preserved in 100% of patients. Conversely, fat planes between the pancreas and the superior mesenteric vein, inferior vena cava, and adjacent bowel loops were partially or totally obliterated in 13% to 50% of patients. It is concluded that the absence of fat around the superior mesenteric artery is highly suggestive of pathologic changes of the pancreas, while the lack of fat planes between the pancreas and other splanchnic vessels or bowel loops frequently is normal, and therefore, is an unreliable sign of pancreatic disease. The applications of these findings to the assessment of tumour resectability by CT, and to CT scanning techniques, are discussed. (orig.)

  5. Computed tomography of peripancreatic fat planes

    International Nuclear Information System (INIS)

    Obliteration of peripancreatic fat planes usually is considered an indicator of peripancreatic tumour infiltration in the presence of a malignant mass, or of inflammation of peripancreatic tissues in patients with pancreatitis. However, absence of peripancreatic fat planes also may be found in patients without evidence of pancreatic disease. Hence, CT scans of 125 patients without clinical or computed tomographic evidence of pancreatic disease were evaluated to assess normal variations in the anatomy of the pancreas and its relation to surrounding vessels and bowel loops. The fat plane separating the superior mesenteric artery from the pancreas was preserved in 100% of patients. Conversely, fat planes between the pancreas and the superior mesenteric vein, inferior vena cava, and adjacent bowel loops were partially or totally obliterated in 13% to 50% of patients. It is concluded that the absence of fat around the superior mesenteric artery is highly suggestive of pathologic changes of the pancreas, while the lack of fat planes between the pancreas and other splanchnic vessels or bowel loops frequently is normal, and therefore, is an unreliable sign of pancreatic disease. The applications of these findings to the assessment of tumour resectability by CT, and to CT scanning techniques, are discussed. (orig.)

  6. Reversibility of Whole-Plane SLE

    CERN Document Server

    Zhan, Dapeng

    2010-01-01

    The main result of this paper is that for $\\kappa\\in(0,4]$, whole-plane SLE$_\\kappa$ satisfies reversibility, which means that the time-reversal of a whole-plane SLE$_\\kappa$ trace is still a whole-plane SLE$_\\kappa$ trace. In addition, we find that the time-reversal of a radial SLE$_\\kappa$ trace for $\\kappa\\in(0,4]$ is a disc SLE$_\\kappa$ trace with a marked boundary point. The main tool used in this paper is the stochastic coupling technique, which was introduced to prove the reversibility of chordal SLE$_\\kappa$ for $\\kappa\\in(0,4]$. The reversibility of whole-plane SLE is closely related to the reversibility of certain SLE traces in doubly connected domains connecting two boundary points. Such SLE is defined using the annulus Loewner equation and a drift function $\\Lambda$. For the reversibility to hold, the drift function $\\Lambda$ must satisfy certain PDE. We use the Feynman-Kac representation to find a solution to this PDE, and finally use the solution to prove the reversibility of whole-plane SLE$_\\k...

  7. Focal Plane Metrology for the LSST Camera

    Energy Technology Data Exchange (ETDEWEB)

    A Rasmussen, Andrew P.; Hale, Layton; Kim, Peter; Lee, Eric; Perl, Martin; Schindler, Rafe; Takacs, Peter; Thurston, Timothy; /SLAC

    2007-01-10

    Meeting the science goals for the Large Synoptic Survey Telescope (LSST) translates into a demanding set of imaging performance requirements for the optical system over a wide (3.5{sup o}) field of view. In turn, meeting those imaging requirements necessitates maintaining precise control of the focal plane surface (10 {micro}m P-V) over the entire field of view (640 mm diameter) at the operating temperature (T {approx} -100 C) and over the operational elevation angle range. We briefly describe the hierarchical design approach for the LSST Camera focal plane and the baseline design for assembling the flat focal plane at room temperature. Preliminary results of gravity load and thermal distortion calculations are provided, and early metrological verification of candidate materials under cold thermal conditions are presented. A detailed, generalized method for stitching together sparse metrology data originating from differential, non-contact metrological data acquisition spanning multiple (non-continuous) sensor surfaces making up the focal plane, is described and demonstrated. Finally, we describe some in situ alignment verification alternatives, some of which may be integrated into the camera's focal plane.

  8. Self-complementary plane partitions by Proctor's minuscule method

    OpenAIRE

    Kuperberg, Greg

    1994-01-01

    A method of Proctor [European J. Combin. 5 (1984), no. 4, 331-350] realizes the set of arbitrary plane partitions in a box and the set of symmetric plane partitions as bases of linear representations of Lie groups. We extend this method by realizing transposition and complementation of plane partitions as natural linear transformations of the representations, thereby enumerating symmetric plane partitions, self-complementary plane partitions, and transpose-complement plane partitions in a new...

  9. Solid-state curved focal plane arrays

    Science.gov (United States)

    Nikzad, Shouleh (Inventor); Hoenk, Michael (Inventor); Jones, Todd (Inventor)

    2010-01-01

    The present invention relates to curved focal plane arrays. More specifically, the present invention relates to a system and method for making solid-state curved focal plane arrays from standard and high-purity devices that may be matched to a given optical system. There are two ways to make a curved focal plane arrays starting with the fully fabricated device. One way, is to thin the device and conform it to a curvature. A second way, is to back-illuminate a thick device without making a thinned membrane. The thick device is a special class of devices; for example devices fabricated with high purity silicon. One surface of the device (the non VLSI fabricated surface, also referred to as the back surface) can be polished to form a curved surface.

  10. Plane wave limits and T-duality

    International Nuclear Information System (INIS)

    The Penrose limit is generalized to show that, any leading order solution of the low-energy field equations in any one of the five string theories has a plane wave solution as a limit. This limiting procedure takes into account all the massless fields that may arise and commutes with the T-duality so that any dual solution has again a plane wave limit. The scaling rules used in the limit are unique and stem from the scaling property of the D = 11 supergravity action. Although the leading order dual solutions need not be exact or supersymmetric, their plane wave limits always preserve some portion of the Poincare supersymmetry and solve the relevant field equations in all powers of the string tension parameter. Further properties of the limiting procedure are discussed. (author)

  11. Bayesian network learning with cutting planes

    CERN Document Server

    Cussens, James

    2012-01-01

    The problem of learning the structure of Bayesian networks from complete discrete data with a limit on parent set size is considered. Learning is cast explicitly as an optimisation problem where the goal is to find a BN structure which maximises log marginal likelihood (BDe score). Integer programming, specifically the SCIP framework, is used to solve this optimisation problem. Acyclicity constraints are added to the integer program (IP) during solving in the form of cutting planes. Finding good cutting planes is the key to the success of the approach -the search for such cutting planes is effected using a sub-IP. Results show that this is a particularly fast method for exact BN learning.

  12. Translation planes foundations and construction principles

    CERN Document Server

    Knarr, Norbert

    1995-01-01

    The book discusses various construction principles for translation planes and spreads from a general and unifying point of view and relates them to the theory of kinematic spaces. The book is intended for people working in the field of incidence geometry and can be read by everyone who knows the basic facts about projective and affine planes. The methods developed work especially well for topological spreads of real and complex vector spaces. In particular, a complete classification of all semifield spreads of finite dimensional complex vector spaces is obtained.

  13. Modeling of steady plane thermal detonations

    International Nuclear Information System (INIS)

    Steady plane thermal detonations proceeding through coarse fuel-coolant mixtures have been predicted to exhibit pressures of approximately 104 bar for UO2/Na and approximately 103 bar for Sn/H2O1. Although detailed experimental information for the crucial fragmentation step is still largely lacking, some important preliminary conclusions can nevertheless be drawn from a detailed examination of the jump balances and solution of the steady, separated-flow conservation equations in the fragmentation zone behind the shock. A few key results are presented of some parametric calculations of steady plane thermal detonations, and in addition offer some broader comments. 33 references

  14. Plane strain test for metal sheet characterization

    OpenAIRE

    Flores, Paulo; Bonnet, Félix; Habraken, Anne

    2007-01-01

    This article shows the influence of a plane strain test specimen geometry on the measurable strain field and the influence of free edge effects over the stress computation. The experimental strain field distribution is measured over the whole deformable zone of a plane strain test specimen by an optical strain gauge. The chosen material is the DC06 IF steel of 0.8 mm thickness. The stress field is computed for several geometries at different strain levels by a Finite Element (FE) commer...

  15. Bifurcation of plane-to-plane map-germs with corank two of parabolic type

    OpenAIRE

    Yoshida, Toshiki; Kabata, Yutaro; Ohmoto, Toru

    2015-01-01

    We study a moduli stratum of A-orbits of plane-to-plane germs of corank 2 with codimension 3. We describe explicitly the bifurcation diagram of its topologically A-versal unfolding. Two geometric applications to parabolic objects are presented.

  16. Deep-Plane Lipoabdominoplasty in East Asians

    Science.gov (United States)

    Jang, Jun-Young; Hong, Yoon Gi; Sim, Hyung Bo; Sun, Sang Hoon

    2016-01-01

    Background The objective of this study was to develop a new surgical technique by combining traditional abdominoplasty with liposuction. This combination of operations permits simpler and more accurate management of various abdominal deformities. In lipoabdominoplasty, the combination of techniques is of paramount concern. Herein, we introduce a new combination of liposuction and abdominoplasty using deep-plane flap sliding to maximize the benefits of both techniques. Methods Deep-plane lipoabdominoplasty was performed in 143 patients between January 2007 and May 2014. We applied extensive liposuction on the entire abdomen followed by a sliding flap through the deep plane after repairing the diastasis recti. The abdominal wound closure was completed with repair of Scarpa's fascia. Results The average amount of liposuction aspirate was 1,400 mL (700–3,100 mL), and the size of the average excised skin ellipse was 21.78×12.81 cm (from 15×10 to 25×15 cm). There were no major complications such as deep-vein thrombosis or pulmonary embolism. We encountered 22 cases of minor complications: one wound infection, one case of skin necrosis, two cases of undercorrection, nine hypertrophic scars, and nine seromas. These complications were solved by conservative management or simple revision. Conclusions The use of deep-plane lipoabdominoplasty can correct abdominal deformities more effectively and with fewer complications than traditional abdominoplasty. PMID:27462568

  17. Large Format Multicolor QWIP Focal Plane Arrays

    Science.gov (United States)

    Soibel, A.; Gunapala, S. D.; Bandara, S. V.; Liu, J. K.; Mumolo, J. M.; Ting, D. Z.; Hill, C. J.; Nguyen, J.

    2009-01-01

    Mid-wave infrared (MWIR) and long-wave infrared (LWIR) multicolor focal plane array (FPA) cameras are essential for many DoD and NASA applications including Earth and planetary remote sensing. In this paper we summarize our recent development of large format multicolor QWIP FPA that cover MWIR and LWIR bands.

  18. Cues for localization in the horizontal plane

    DEFF Research Database (Denmark)

    Jeppesen, Jakob; Møller, Henrik

    2005-01-01

    manipulated in HRTFs used for binaural synthesis of sound in the horizontal plane. The manipulation of cues resulted in HRTFs with cues ranging from correct combinations of spectral information and ITDs to combinations with severely conflicting cues. Both the ITD and the spectral information seem to be...

  19. Locating a minisum circle in the plane

    DEFF Research Database (Denmark)

    Brimberg, Jack; Juel, Henrik; Schöbel, Anita

    2009-01-01

    We consider the problem of locating a circle with respect to existing facilities in the plane such that the sum of weighted distances between the circle and the facilities is minimized, i.e., we approximate a set of given points by a circle regarding the sum of weighted distances. If the radius of...

  20. Spatial Reasoning and Polya's Five Planes Problem

    Science.gov (United States)

    Madden, Sean P.; Diaz, Ricardo

    2008-01-01

    Middle and High school students of the twenty-first century possess surprising powers of spatial reasoning. They are assisted by technologies not available to earlier generations. Both of these assertions are demonstrated by students who are challenged with George Polya's classic Five Planes Problem. (Contains 5 figures.)

  1. Infrared MUSIC from Z technology focal planes

    International Nuclear Information System (INIS)

    Presented is the Multiple Signal Classification (MUSIC) algorithm which uses the high frequency differences in sensed time signals to discriminate, count, and accurately locate closely spaced targets. Z technology focal planes allow the implementation of this algorithm and the trade-off between finer spatial resolution systems and systems with coarser resolution but higher sampling rates

  2. Personnel thermoluminescent dosimetry of plane pilots

    International Nuclear Information System (INIS)

    In this work are presented the results of the research realized in the pilots of commercial planes of the different flight equipment existing. The results obtained show that the pilots receive during their work, doses of ionizing radiation greater than the limit recommended by the International Commission of Radiological Protection. (Author)

  3. Optical interconnections to focal plane arrays

    Energy Technology Data Exchange (ETDEWEB)

    Rienstra, J.L.; Hinckley, M.K.

    2000-11-01

    The authors have successfully demonstrated an optical data interconnection from the output of a focal plane array to the downstream data acquisition electronics. The demonstrated approach included a continuous wave laser beam directed at a multiple quantum well reflectance modulator connected to the focal plane array analog output. The output waveform from the optical interconnect was observed on an oscilloscope to be a replica of the input signal. They fed the output of the optical data link to the same data acquisition system used to characterize focal plane array performance. Measurements of the signal to noise ratio at the input and output of the optical interconnection showed that the signal to noise ratio was reduced by a factor of 10 or more. Analysis of the noise and link gain showed that the primary contributors to the additional noise were laser intensity noise and photodetector receiver noise. Subsequent efforts should be able to reduce these noise sources considerably and should result in substantially improved signal to noise performance. They also observed significant photocurrent generation in the reflectance modulator that imposes a current load on the focal plane array output amplifier. This current loading is an issue with the demonstrated approach because it tends to negate the power saving feature of the reflectance modulator interconnection concept.

  4. Elastic Constants of Plane Orthotropic Elasticity

    DEFF Research Database (Denmark)

    Krenk, Steen

    1979-01-01

    The four independent material parameters of plane orthotropic elasti city are introduced as the effective stiffness, the effective Poisson ratio, the stiffness ratio and the shear parameter. It is proved that stress boundary value problems with zero resulting force on internal contours lead to st...

  5. Some Reflections on Plane Mirrors and Images.

    Science.gov (United States)

    Galili, Igal; And Others

    1991-01-01

    Discusses the following questions based on the assumption that students' personal experiences and prior beliefs about plane mirrors can promote interesting discussions: (1) How mirror images are formed? (2) Why doesn't paper behave like a mirror? (3) Does a mirror left-right reverse objects? and (4) Why are corner images of two perpendicular…

  6. Plane wave fast color flow mode imaging

    DEFF Research Database (Denmark)

    Bolic, Ibrahim; Udesen, Jesper; Gran, Fredrik;

    2006-01-01

    A new Plane wave fast color flow imaging method (PWM) has been investigated, and performance evaluation of the PWM based on experimental measurements has been made. The results show that it is possible to obtain a CFM image using only 8 echo-pulse emissions for beam to flow angles between 45...

  7. Crack initiation under generalized plane strain conditions

    International Nuclear Information System (INIS)

    A method for estimating the decrease in crack-initiation toughness, from a reference plane strain value, due to positive straining along the crack front of a circumferential flaw in a reactor pressure vessel is presented in this study. This method relates crack initiation under generalized plane strain conditions with material failure at points within a distance of a few crack-tip-opening displacements ahead of a crack front, and involves the formulation of a micromechanical crack-initiation model. While this study is intended to address concerns regarding the effects of positive out-of- plane straining on ductile crack initiation, the approach adopted in this work can be extended in a straightforward fashion to examine conditions of macroscopic cleavage crack initiation. Provided single- parameter dominance of near-tip fields exists in the flawed structure, results from this study could be used to examine the appropriateness of applying plane strain fracture toughness to the evaluation of circumferential flaws, in particular to those in ring-forged vessels which have no longitudinal welds. In addition, results from this study could also be applied toward the analysis of the effects of thermal streaming on the fracture resistance of circumferentially oriented flaws in a pressure vessel. 37 refs., 8 figs., 1 tab

  8. MTI Focal Plane Assembly Design and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Ballard, M.; Rienstra, J.L.

    1999-06-17

    The focal plane assembly for the Multispectral Thermal Imager (MTI) consists of sensor chip assemblies, optical filters, and a vacuum enclosure. Sensor chip assemblies, composed of linear detector arrays and readout integrated circuits, provide spatial resolution in the cross-track direction for the pushbroom imager. Optical filters define 15 spectral bands in a range from 0.45 {micro}m to 10.7 {micro}m. All the detector arrays are mounted on a single focal plane and are designed to operate at 75 K. Three pairs of sensor chip assemblies (SCAs) are required to provide cross-track coverage in all 15 spectral bands. Each pair of SCAs includes detector arrays made from silicon, iridium antimonide, and mercury cadmium telluride. Read out integrated circuits multiplex the signals from the detectors to 18 separate video channels. Optical filter assemblies defining the spectral bands are mounted over the linear detector arrays. Each filter assembly consists of several filter strips bonded together side-by-side. The MTI focal plane assembly has been integrated with the rest of the payload and has undergone detailed testing and calibration. This paper includes representative test data for the various spectral bands and the overall performance of the focal plane assembly.

  9. Field in a plane plasma waveguide

    International Nuclear Information System (INIS)

    Representation of electromagnetic field radiated from harmonic source placed in a plane waveguide filled with cold electron plasma is given. Radiation-mode and hybrid representation of this field depend on frequency of source is discussed. 7 refs., 3 figs. (L.I.)

  10. Simple Harmonic Motion in Harmonic Plane Waves.

    Science.gov (United States)

    Benumof, Reuben

    1980-01-01

    Discusses the distribution of kinetic and potential energy in transverse and longitudinal waves and examines the transmission of power and momentum. This discussion is intended to aid in understanding the simple harmonic motion of a particle involved in the propagation of a harmonic mechanical plane wave. (HM)

  11. Sonnenemertes cantelli gen. et sp. nov. (Heteronemertea)-A new Oxypolella-like nemertean from the abyssal plain adjacent to the Kuril-Kamchatka Trench

    Science.gov (United States)

    Chernyshev, Alexei V.; Abukawa, Shushi; Kajihara, Hiroshi

    2015-01-01

    Approximately 129 nemertean specimens were obtained in the material collected by the Russian-German KuramBio expedition 2012 to the abyssal plain adjacent to the Kuril-Kamchatka Trench (KKT). Due to deformed, fragmentary condition of most of the collected nemerteans they were identified to the order level only. Both archi- and heteronemerteans were very rare, and tubulanid palaeonemerteans and hoplonemerteans were predominant in the KuramBio epibenthic sledge (EBS) samples. Before the KuramBio expedition, only three species of the World fauna of benthic nemerteans had been known from depths exceeding 3000 m; according to data of Vityaz expedition in the KKT, published in 1955, unidentified nemerteans were found in all trawl samples from depths 1000 to 4640 m, but only one specimen of unidentified nemertean was collected from depths exceeding 5000 m. A reliable estimation of the actual species diversity of the present KuramBio samples could have been made primarily based on molecular genetic analyses; almost all the collected specimens are likely to represent undescribed species. In this study, a new species of the heteronemertean, Sonnenemertes cantelli gen. et sp. nov., from a depth of approximately 4870 m is described. This is the deepest record for an identified benthic nemertean, as well as the first species of the subfamily Oxypolellinae from the North Pacific. A single specimen was examined by light microscopy, scanning electron microscopy, and confocal laser scanning microscopy with phalloidin and antibody labeling. Morphologically, this species is similar to those in the genus Oxypolella. A preliminary molecular phylogenetic analysis based on partial 16S rDNA among the selected heteronemertean species indicated that S. cantelli formed a monophyletic group with Oxypolella alba Bergendal, 1903 together as a sister to the genus Baseodiscus. Systematic positioning of Oxypolella, Sonnenemertes, and related genera is discussed.

  12. Biogeochemical variations at the Porcupine Abyssal Plain Sustained Observatory (PAP-SO) in the northeast Atlantic Ocean, from weekly to inter-annual time scales

    Science.gov (United States)

    Hartman, Susan; Lampitt, Richard

    2015-04-01

    We present high-resolution autonomous measurements of carbon dioxide partial pres- sure p(CO2) taken in situ at the Porcupine Abyssal Plain sustained observatory (PAP- SO) in the northeast Atlantic (49N, 16.5W; water depth of 4850 m) for the period 2010 to 2012. Measurements of p(CO2) made at 30 m depth on a sensor frame are compared with other autonomous biogeochemical measurements at that depth (including chlorophyll a-fluorescence and nitrate concentration data) to analyse weekly to seasonal controls on p(CO2) flux in the inter-gyre region of the North Atlantic. Comparisons are also made with in situ regional time-series data from a ship of opportunity and mixed layer depth (MLD) measurements from profiling Argo floats. There is a persistent under saturation of CO2 in surface waters throughout the year which gives rise to a perennial CO2 sink. Comparison with an earlier dataset collected at the site (2003 to 2005) confirms seasonal and inter-annual changes in surface seawater chemistry. There is year-to-year variability in the timing of deep winter mixing and the intensity of the spring bloom. The 2010-2012 period shows an overall increase in p(CO2) values when compared to the 2003-2005 period as would be expected from increases due to anthropogenic CO2 emissions. The surface temperature, wind speed and MLD measurements are similar for both periods of time. Future work should incorporate daily CO2 flux measurements made using CO2 sensors at 1 m depth and the in situ wind speed data now available from the UK Met Office Buoy.

  13. On building 4-critical plane and projective plane multiwheels from odd wheels

    CERN Document Server

    Zeps, Dainis

    2012-01-01

    We build unbounded classes of plane and projective plane multiwheels that are 4-critical that are received summing odd wheels as edge sums modulo two. These classes can be considered as ascending from single common graph that can be received as edge sum modulo two of the octahedron graph O and the minimal wheel W3. All graphs of these classes belong to 2n-2-edges-class of graphs, among which are those that quadrangulate projective plane, i.e., graphs from Gr\\"otzsch class, received applying Mycielski's Construction to odd cycle.

  14. Progress on VLBI Ecliptic Plane Survey

    CERN Document Server

    Shu, Fengchun; Jiang, Wu; McCallum, Jamie; Yi, Sang-oh; Takefuji, Kazuhiro; Li, Jinling; Lovell, Jim

    2016-01-01

    We launched the VLBI Ecliptic Plane Survey program in 2015. The goal of this program is to find all compact sources within 7.5 degrees of the ecliptic plane which are suitable as phase calibrators for anticipated phase referencing observations of spacecrafts. We planned to observe a complete sample of the sources brighter than 50 mJy at 5 GHz listed in the PMN and GB6 catalogues that have not yet been observed with VLBI. By April 2016, eight 24-hour sessions have been performed and processed. Among 2227 observed sources, 435 sources were detected in three or more observations. We have also run three 8-hour segments with VLBA for improving positions of 71 ecliptic sources.

  15. Heteroclinic connections in plane Couette flow

    CERN Document Server

    Halcrow, Jonathan; Cvitanović, Predrag; Viswanath, Divakar

    2008-01-01

    Plane Couette flow transitions to turbulence for Re~325 even though the laminar solution with a linear profile is linearly stable for all Re (Reynolds number). One starting point for understanding this subcritical transition is the existence of invariant sets in the state space of the Navier Stokes equation, such as upper and lower branch equilibria and periodic and relative periodic solutions, that are quite distinct from the laminar solution. This article reports several heteroclinic connections between such objects and briefly describes a numerical method for locating heteroclinic connections. Computing such connections is essential for understanding the global dynamics of spatially localized structures that occur in transitional plane Couette flow. We show that the nature of streaks and streamwise rolls can change significantly along a heteroclinic connection.

  16. Focal Plane Image Assembly of Subpixel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper describes the scanning assembly principle and construction of scanning assembly sample.The factors that affect assembly accuracy are analyzed.There are two steps in CCD focal plane scanning assembly.The first is rough assembly,and the second is accurate assembly.In this paper,the moiré fringe is introduced in judging assembly accuracy directly and accurately.The equation for optical transmission characteristics of CCD Moiré fringes is presented.The measurement of Moiré fringes can be completed when some conditions are satisfied.2D-assembly error can be obtained by using digital correlation filtering technique.Finally,the result of focal plane scanning assembly is presented.The result is in good accordance with theory.

  17. Suicide plane crash against nuclear power plants

    International Nuclear Information System (INIS)

    Cea (French atomic energy commission) and EDF (Electricity of France) are reassessing their safety standards concerning suicide plane attacks against nuclear facilities. The general idea is to study the non-linear behaviour of reinforced concrete in case of mechanical impact. American studies carried out in 1988 show that a F-14 phantom crashing into a 3,6 meter thick wall at a speed of 774 km/h penetrates only the first 5 cm of the wall. More recent studies performed in Germany and based on computerized simulations show that the reactor containment can sustain impacts from a F15 plane or even from a 747-Boeing but contiguous buildings like the one which houses spent fuels might be more easily damaged because of their metal roofing. (A.C.)

  18. Waveguide metacouplers for in-plane polarimetry

    CERN Document Server

    Pors, Anders

    2016-01-01

    The state of polarization (SOP) is an inherent property of the vectorial nature of light and a crucial parameter in a wide range of remote sensing applications. Nevertheless, the SOP is rather cumbersome to probe experimentally, as conventional detectors only respond to the intensity of the light, hence loosing the phase information between orthogonal vector components. In this work, we propose a new type of polarimeter that is compact and well-suited for in-plane optical circuitry, while allowing for immediate determination of the SOP through simultaneous retrieval of the associated Stokes parameters. The polarimeter is based on plasmonic phase-gradient birefringent metasurfaces that facilitate normal incident light to launch in-plane photonic waveguide modes propagating in six predefined directions with the coupling efficiencies providing a direct measure of the incident SOP. The functionality and accuracy of the polarimeter, which essentially is an all-polarization sensitive waveguide metacoupler, is confi...

  19. Worldvolume supersymmetries for branes in plane waves

    CERN Document Server

    Freedman, D Z; Taylor, M; Freedman, Daniel Z.; Skenderis, Kostas; Taylor, Marika

    2003-01-01

    We study the worldvolume supersymmetries of M2 branes in the maximally supersymmetric plane wave background of M theory. For certain embeddings the standard probe analysis indicates that the worldvolume theory has less than 16 supersymmetries. We show that at the quadratic level the worldvolume theory admits additional linearly realized supersymmetries, and that the spectra of the branes are organized into multiplets of these symmetries. We find however that these supersymmetries are not respected by worldvolume interactions. Our analysis was motivated by recent work showing that D-branes in the maximally supersymmetric plane wave background of IIB string theory admit supersymmetries beyond those of the probe analysis. The construction of the additional supercharges in this case was specific to a string worldsheet that is a strip and the present results suggest that string interactions do not preserve these symmetries.

  20. On the map of Vogel's plane

    CERN Document Server

    Mkrtchyan, R L

    2013-01-01

    We search points in a Vogel plane with regular universal expression for character of adjoint representation. This gives seven patterns of singularities cancellation, each giving a certain Diophantine equation of third order on three variables. Solutions of these equations are classical series of simple Lie algebras (including an "odd symplectic" one), $D_{2,1,\\lambda}$ superalgebra, the straight line of three-dimensional algebras, and a number of isolated solutions, including exceptional simple Lie algebras. One of these Diophantine equations, namely knm=4k+4n+2m+12 contains all simple Lie algebras, except SO(2N+1). Isolated solutions contain, beside exceptional simple Lie algebras, so called $E_{71/2}$ algebra and also two other similar (unknown) objects with positive dimensions. In addition, there are 47 isolated solutions in "unphysical semiplane" with negative dimensions. Isolated solutions mainly lie on a few straight lines in Vogel plane. All solutions give an integers in universal dimension formulae fo...

  1. String theory on Dp-plane waves

    International Nuclear Information System (INIS)

    We study the spectrum of solvable string models on plane waves descending from non-conformal Dp-brane geometries. We mainly focus on S-dual F1/D1-waves in type-IIB and type-I/heterotic 10D superstrings. We derive the Kaluza-Klein spectrum of N=1,2 10D supergravities on D1/F1-waves. We compute helicity supertraces counting multiplicities and R-charges of string excitations in the plane wave geometry. The results are compared against the expectations coming from gauge/supergravity descriptions. In the type I case, the Klein, Annulus and Moebius one-loop amplitudes are computed for ten-dimensional D1-waves. We test the consistency of the open string descendant by showing that after modular transformations to the closed string channel, the three amplitudes combine themselves to reconstruct a complete square (vertical bar B> + vertical bar C>)2. Tadpole conditions are also discussed. (author)

  2. Structure analysis for plane geometry figures

    Science.gov (United States)

    Feng, Tianxiao; Lu, Xiaoqing; Liu, Lu; Li, Keqiang; Tang, Zhi

    2013-12-01

    As there are increasing numbers of digital documents for education purpose, we realize that there is not a retrieval application for mathematic plane geometry images. In this paper, we propose a method for retrieving plane geometry figures (PGFs), which often appear in geometry books and digital documents. First, detecting algorithms are applied to detect common basic geometry shapes from a PGF image. Based on all basic shapes, we analyze the structural relationships between two basic shapes and combine some of them to a compound shape to build the PGF descriptor. Afterwards, we apply matching function to retrieve candidate PGF images with ranking. The great contribution of the paper is that we propose a structure analysis method to better describe the spatial relationships in such image composed of many overlapped shapes. Experimental results demonstrate that our analysis method and shape descriptor can obtain good retrieval results with relatively high effectiveness and efficiency.

  3. Crisis bifurcations in plane Poiseuille flow

    CERN Document Server

    Zammert, Stefan

    2015-01-01

    Direct numerical simulations of transitional plane Poiseuille flow in a mirror-symmetric subspace reveal several interior and exterior crisis bifurcations. They appear in the upper branch that emerges in a saddle-node bifurcation near $Re_{SN}=641$ and then undergoes several bifurcations into a chaotic attractor. Near $Re_{XC}=785.95$ the attractor collides with the lower-branch state and turns into a chaotic saddle in a exterior crisis, with a characteristic $(Re-Re_{XC})^{-\\delta}$ variation in lifetimes. For intermediate Reynolds numbers, the attractor undergoes several interior crises, in which new states appear and intermittent behavior can be observed. They contribute to increasing the complexity of the dynamics and to a more dense coverage of state space. The exterior crisis marks the onset of transient turbulence in this subspace of plane Poiseuille flow.

  4. Cues for localization in the horizontal plane

    DEFF Research Database (Denmark)

    Jeppesen, Jakob; Møller, Henrik

    2005-01-01

    Spatial localization of sound is often described as unconscious evaluation of cues given by the interaural time difference (ITD) and the spectral information of the sound that reaches the two ears. Our present knowledge suggests the hypothesis that the ITD roughly determines the cone of the perce...... independently in HRTFs used for binaural synthesis. The ITD seems to be dominant for localization in the horizontal plane even when the spectral information is severely degraded....

  5. Plane correlations in small colliding systems

    CERN Document Server

    Yan, Li

    2015-01-01

    I propose event-plane correlations as a test of collectivity in small colliding systems: In d-Au and $^3$He-Au collisions, I predict a strong anti-correlation between elliptic and triangular flow, generated by the geometry of the light projectile. A significant anti-correlation is also predicted in central p-Pb collisions at the LHC, which is solely generated by fluctuations. Similar, but stronger correlation patterns are predicted in correlations involving dipolar flow.

  6. STABLE AND UNSTABLE IDEAL PLANE FLOWS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The authors investigate the stability of a steady ideal plane flow in an arbitrary domain in terms of the L2 norm of the vorticity. Linear stability implies nonlinear instability provided the growth rate of the linearized system exceeds the Liapunov exponent of the flow. In contrast,a maximizer of the entropy subject to constant energy and mass is stable. This implies the stability of certain solutions of the mean field equation.

  7. Free string evolution across plane wave singularities

    CERN Document Server

    Craps, Ben; Evnin, Oleg

    2009-01-01

    In these proceedings, we summarize our studies of free string propagation in (near-)singular scale-invariant plane wave geometries. We analyze the singular limit of the evolution for the center-of-mass motion and all excited string modes. The requirement that the entire excitation energy of the string should be finite excludes consistent propagation across the singularity, in case no dimensionful scales are introduced at the singular locus (in an otherwise scale-invariant space-time).

  8. Plane sets invisible in finitely many directions

    OpenAIRE

    Plakhov, Alexander

    2015-01-01

    We consider the problem of mirror invisibility for plane sets. Given a circle and a finite number of unit vectors (defining the directions of invisibility) such that the angles between them are commensurable with $\\pi$, for any $\\varepsilon > 0$ there exists a set invisible in the chosen directions that contains the circle and is contained in its $\\varepsilon$-neighborhood. This set is the disjoint union of infinitely many domains with piecewise smooth boundary.

  9. Counterpropagating Rossby waves in confined plane wakes

    OpenAIRE

    Biancofiore, L.; Gallaire, F.

    2012-01-01

    In the present work, we revisit the temporal and the spatio-temporal stability of confined plane wakes under the perspective of the counterpropagating Rossby waves (CRWs). Within the context of broken line velocity profiles, each vorticity discontinuity can be associated to a counterpropagating Rossby wave. In the case of a wake modeled by a broken line profile, the interaction of two CRWs is shown to originate in a shear instability. Following this description, we first recover the stability...

  10. Hard Discs on the Hyperbolic Plane

    OpenAIRE

    Modes, Carl D.; Kamien, Randall D.

    2007-01-01

    We examine a simple hard disc fluid with no long range interactions on the two dimensional space of constant negative Gaussian curvature, the hyperbolic plane. This geometry provides a natural mechanism by which global crystalline order is frustrated, allowing us to construct a tractable model of disordered monodisperse hard discs. We extend free area theory and the virial expansion to this regime, deriving the equation of state for the system, and compare its predictions with simulation near...

  11. Plane strain problem in microstretch elastic solid

    Indian Academy of Sciences (India)

    Rajneesh Kumar; Ranjit Singh; T K Chadha

    2003-12-01

    The eigenvalue approach is developed for the two-dimensional plane strain problem in a microstretch elastic medium. Applying Laplace and Fourier transforms, an infinite space subjected to a concentrated force is studied. The integral transforms are inverted using a numerical technique to get displacement, force stress, couple stress and first moment, which are also shown graphically. The results of micropolar elasticity are deduced as a special case from the present formulation.

  12. Restoring Aperture Profile At Sample Plane

    International Nuclear Information System (INIS)

    Off-line conditioning of full-size optics for the National Ignition Facility required a beam delivery system to allow conditioning lasers to rapidly raster scan samples while achieving several technical goals. The main purpose of the optical system designed was to reconstruct at the sample plane the flat beam profile found at the laser aperture with significant reductions in beam wander to improve scan times. Another design goal was the ability to vary the beam size at the sample to scan at different fluences while utilizing all of the laser power and minimizing processing time. An optical solution was developed using commercial off-the-shelf lenses. The system incorporates a six meter relay telescope and two sets of focusing optics. The spacing of the focusing optics is changed to allow the fluence on the sample to vary from 2 to 14 Joules per square centimeter in discrete steps. More importantly, these optics use the special properties of image relaying to image the aperture plane onto the sample to form a pupil relay with a beam profile corresponding almost exactly to the flat profile found at the aperture. A flat beam profile speeds scanning by providing a uniform intensity across a larger area on the sample. The relayed pupil plane is more stable with regards to jitter and beam wander. Image relaying also reduces other perturbations from diffraction, scatter, and focus conditions. Image relaying, laser conditioning, and the optical system designed to accomplish the stated goals are discussed

  13. Hamiltonian maps in the complex plane

    International Nuclear Information System (INIS)

    Following Arnol'd's proof of the KAM theorem, an analogy with the vertical pendulum, and some general arguments concerning maps in the complex plane, detailed calculations are presented and illustrated graphically for the standard map at the golden mean frequency. The functional dependence of the coordinate q on the canonical angle variable theta is analytically continued into the complex theta-plane, where natural boundaries are found at constant absolute values of Im theta. The boundaries represent the appearance of chaotic motion in the complex plane. Two independent numerical methods based on Fourier analysis in the angle variable were used, one based on a variation-annihilation method and the other on a double expansion. The results were further checked by direct solution of the complex equations of motion. The numerically simpler, but intrinsically complex, semipendulum and semistandard map are also studied. We conjecture that natural boundaries appear in the analogous analytic continuation of the invariant tori or KAM surfaces of general nonintegrable systems

  14. On the Road Map of Vogel's Plane

    Science.gov (United States)

    Mkrtchyan, Ruben L.

    2016-01-01

    We define "population" of Vogel's plane as points for which universal character of adjoint representation is regular in the finite plane of its argument. It is shown that they are given exactly by all solutions of seven Diophantine equations of third order on three variables. We find all their solutions: classical series of simple Lie algebras (including an "odd symplectic" one), {D_{2,1,λ}} superalgebra, the line of sl(2) algebras, and a number of isolated solutions, including exceptional simple Lie algebras. One of these Diophantine equations, namely {knm=4k+4n+2m+12,} contains all simple Lie algebras, except so{(2N+1).} Among isolated solutions are, besides exceptional simple Lie algebras, so called {e_{71/2}} algebra and also two other similar unidentified objects with positive dimensions. In addition, there are 47 isolated solutions in "unphysical semiplane" with negative dimensions. Isolated solutions mainly belong to the few lines in Vogel plane, including some rows of Freudenthal magic square. Universal dimension formulae have an integer values on all these solutions at least for first three symmetric powers of adjoint representation.

  15. Seasonal and inter-annual biogeochemical variations in the Porcupine Abyssal Plain 2003-2005 associated with winter mixing and surface circulation

    Science.gov (United States)

    Hartman, S. E.; Larkin, K. E.; Lampitt, R. S.; Lankhorst, M.; Hydes, D. J.

    2010-08-01

    We present a 3-year multidisciplinary biogeochemical data set taken in situ at the Porcupine Abyssal Plain (PAP) time-series observatory in the Northeast Atlantic (49°N, 16.5°W; water depth ˜4850 m) for the period 2003 to 2005. The high-resolution year-round autonomous measurements include temperature, salinity, chlorophyll-a (derived from in situ chlorophyll-fluorescence) and inorganic nitrate, all at a nominal depth of 30 m on an Eulerian observatory mooring. This study compares these in situ time-series data with satellite chlorophyll-a data, regional data from a ship of opportunity, mixed-layer depth measurements from profiling Argo floats and lateral advection estimates from altimetry. This combined and substantial data set is used to analyse seasonal and inter-annual variability in hydrography and nitrate concentrations in relation to convective mixing and lateral advection. The PAP observatory site is in the inter-gyre region of the North Atlantic where convective mixing ranges from 25 m in the summer to over 400 m in winter when nutrients are supplied to the surface. Small inter-annual changes in the winter mixed layer can result in large changes in nitrate supply and productivity. However the decrease in maximum winter nitrate over the three-year period, from 10 to 7 mmol m -3, cannot be fully explained by convective mixing. Trajectories leading to the PAP site, computed from altimetry-derived geostrophic velocities, confirm that lateral advection cannot be ignored at this site and may be an important process along with convective mixing. Over the three years, there is an associated decrease in new production calculated from nitrate assimilation from 85.4 to 40.3±4.3 gCm -2 a -1. This confirms year-to-year variability in primary production seen in model estimates for the region. The continuous in situ dataset also shows inter-annual variation in the timing of the spring bloom due to variations in heat flux; the 2005 bloom occurred earlier than in 2004.

  16. Simulation Exploration through Immersive Parallel Planes: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Brunhart-Lupo, Nicholas; Bush, Brian W.; Gruchalla, Kenny; Smith, Steve

    2016-03-01

    We present a visualization-driven simulation system that tightly couples systems dynamics simulations with an immersive virtual environment to allow analysts to rapidly develop and test hypotheses in a high-dimensional parameter space. To accomplish this, we generalize the two-dimensional parallel-coordinates statistical graphic as an immersive 'parallel-planes' visualization for multivariate time series emitted by simulations running in parallel with the visualization. In contrast to traditional parallel coordinate's mapping the multivariate dimensions onto coordinate axes represented by a series of parallel lines, we map pairs of the multivariate dimensions onto a series of parallel rectangles. As in the case of parallel coordinates, each individual observation in the dataset is mapped to a polyline whose vertices coincide with its coordinate values. Regions of the rectangles can be 'brushed' to highlight and select observations of interest: a 'slider' control allows the user to filter the observations by their time coordinate. In an immersive virtual environment, users interact with the parallel planes using a joystick that can select regions on the planes, manipulate selection, and filter time. The brushing and selection actions are used to both explore existing data as well as to launch additional simulations corresponding to the visually selected portions of the input parameter space. As soon as the new simulations complete, their resulting observations are displayed in the virtual environment. This tight feedback loop between simulation and immersive analytics accelerates users' realization of insights about the simulation and its output.

  17. Characterization of DECam focal plane detectors

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, H.Thomas; Angstadt, Robert; Campa, Julia; Cease, Herman; Derylo, Greg; Emes, John H.; Estrada, Juan; Kibik, Donna; Flaugher, Brenna L.; Holland, Steve E.; Jonas, Michelle; /Fermilab /Madrid, CIEMAT /LBL, Berkeley /Argonne /Pennsylvania U.

    2008-06-01

    DECam is a 520 Mpix, 3 square-deg FOV imager being built for the Blanco 4m Telescope at CTIO. This facility instrument will be used for the 'Dark Energy Survey' of the southern galactic cap. DECam has chosen 250 ?m thick CCDs, developed at LBNL, with good QE in the near IR for the focal plane. In this work we present the characterization of these detectors done by the DES team, and compare it to the DECam technical requirements. The results demonstrate that the detectors satisfy the needs for instrument.

  18. Symmetric cumulants and event-plane correlations

    CERN Document Server

    Giacalone, Giuliano; Noronha-Hostler, Jacquelyn; Ollitrault, Jean-Yves

    2016-01-01

    The ALICE Collaboration has recently measured the correlations between amplitudes of anisotropic flow in different Fourier harmonics, referred to as symmetric cumulants. We derive approximate relations between symmetric cumulants involving $v_4$ and $v_5$ and the event-plane correlations measured by ATLAS. The validity of these relations is tested using event-by-event hydrodynamic calculations. The corresponding results are in better agreement with ALICE data than existing hydrodynamic predictions. We make quantitative predictions for three symmetric cumulants which are not yet measured.

  19. The space complexity of cutting planes refutations

    Czech Academy of Sciences Publication Activity Database

    Galesi, N.; Pudlák, Pavel; Thapen, Neil

    Dagstuhl : Schloss Dagstuhl, Leibniz-Zentrum für Informatik, 2015 - (Zuckerman, D.), s. 433-447 ISBN 978-3-939897-81-1. ISSN 1868-8969. - (Leibniz International Proceedings in Informatics. 33). [Conference on Computational Complexity (CCC) /30./. Portland (US), 17.06.2015-19.06.2015] R&D Projects: GA ČR GBP202/12/G061 EU Projects: European Commission(XE) 339691 - FEALORA Institutional support: RVO:67985840 Keywords : proof complexity * space * cutting planes Subject RIV: BA - General Mathematics http://drops.dagstuhl.de/opus/volltexte/2015/5055/

  20. The quasar mass-luminosity plane

    Science.gov (United States)

    Steinhardt, Charles Louis

    2010-11-01

    This thesis investigates the quasar mass-luminosity plane, as a new tool to explore the relationship between black hole mass and quasar luminosity over time. Previous techniques used quasar luminosity function and mass functions, which are one-dimensional projections of the mass-luminosity plane. The M --- L plane contains information that cannot be seen in these projections. We use 62,185 quasars from the Sloan Digital Sky Survey DR5 sample to develop several new constraints on quasar accretion. Black hole masses, based on the widths of their Hbeta, Mg II, and C IV lines and adjacent continuum luminosities, were used assuming using standard virial mass estimate scaling laws. In each redshift interval over the range 0.2 4.0, low-mass quasars reach at their Eddington luminosity, but high-mass quasars fall short, even by a factor of ten or more at 0.2 < z < 0.6. We examine several potential sources of measurement uncertainty or bias and show that none of them can account for this effect. We also show the statistical uncertainty in virial mass estimation to have an upper bound of ˜ 0.2 dex, smaller than the 0.4 dex previously reported. The maximum mass of quasars at each redshift is sharp and evolving. High-mass black holes turn off their luminous accretion at higher redshift than lower-mass black holes. Further, turnoff for quasars at any given mass is synchronized to within 0.7--3 Gyr, tighter than would be expected given the dynamics of their host galaxies. We find potential signatures of the quasar turnoff mechanism, including a dearth of high-mass quasars at low Eddington ratio, low CIV/MgII emission line ratio, and a red spectral tilt. Finally, we use these new constraints to analyze models for the evolution of individual quasars over time. We find a restricted family of tracks that lie within the M --- L plane at all redshifts, suggesting that a single, constant feedback mechanism between all supermassive black holes and their host galaxies might apply at all

  1. Optimizing snake locomotion on an inclined plane

    CERN Document Server

    Wang, Xiaolin; Alben, Silas

    2013-01-01

    We develop a model to study the locomotion of snakes on an inclined plane. We determine numerically which snake motions are optimal for two retrograde traveling-wave body shapes---triangular and sinusoidal waves---across a wide range of frictional parameters and incline angles. In the regime of large transverse friction coefficient, we find power-law scalings for the optimal wave amplitudes and corresponding costs of locomotion. We give an asymptotic analysis to show that the optimal snake motions are traveling-wave motions with amplitudes given by the same scaling laws found in the numerics.

  2. Structure Scalars In Charged Plane Symmetry

    CERN Document Server

    Sharif, M

    2013-01-01

    We consider non-adiabatic flow of the fluid possessing dissipation in the form of shearing viscosity in electromagnetic field. The scalar functions (structure scalars) for charged plane symmetry are formulated and are related with the physical variables of the fluid. We also develop a relationship between the Weyl tensor and other physical variables by using Taub mass formalism. The role of electric charge as well as its physical significance for the evolution of the shear tensor and expansion scalar are also explored. Finally, we discuss a special case for dust with cosmological constant.

  3. Lattice actions on the plane revisited

    CERN Document Server

    Maucourant, Francois

    2010-01-01

    We study the action of a lattice in the group SL(2,R) on the plane. We obtain a formula which simultaneously describes visits of an orbit to either a fixed ball, or an expanding or contracting family of annuli. We also discuss the `shrinking target problem'. Our results are valid for an explicitly described set of initial points: all nonzero vectors in the case of a cocompact lattice, and all vectors satisfying certain diophantine conditions in case SL(2,Z). The proofs combine the method of Ledrappier with effective equidistribution results for the horocycle flow due to Burger, Strombergsson, Forni and Flaminio.

  4. Planes departamentales de CT&I

    OpenAIRE

    Duque Escobar, Gonzalo

    2011-01-01

    Urge la formulación de los Planes de CT&I para los Departamentos, gestionando el territorio como una construcción social, con ideas que den respueta a los retos contemporáneos y medulares de nuestro entorno, tales como: la violencia, la drogadicción y la falta de oportunidades; la inequidad, la exclusión y la pobreza; el consumismo, la contaminación y el calentamiento global; la pérdida de identidad de los pueblos, la fragmentación social y la degradación de los valores éticos; la desestructu...

  5. Conformal field theory on the plane

    CERN Document Server

    Ribault, Sylvain

    2014-01-01

    We provide an introduction to conformal field theory on the plane in the conformal bootstrap approach. We introduce the main ideas of the bootstrap approach to quantum field theory, and how they apply to two-dimensional theories with local conformal symmetry. We describe the mathematical structures which appear in such theories, from the Virasoro algebra and its representations, to the BPZ equations and their solutions. As examples, we study a number of models: Liouville theory, (generalized) minimal models, free bosonic theories, the $H_3^+$ model, and the $SU_2$ and $\\widetilde{SL}_2(\\mathbb{R})$ WZW models.

  6. Planes óptimos con preferencias desconocidas

    OpenAIRE

    Mantel, Rolf R.

    1999-01-01

    Recientemente Rustem y Velupillaj (1985) han vuelto a investigar el "método de las entrevistas" originalmente propuesto por Ragnar Frisch y descripta por Johansen (1974) para la cooperación entre el planificador -abreviatura que se utilizará para designar a el o los responsables de la política económica-y el econometrista -o responsable del modelo económico- para la determinación de un conjunto de medidas de política económica óptimo. Van Eijk y Sandee (1959) ya habían propuesto diseñar plane...

  7. Brane webs and O5-planes

    Science.gov (United States)

    Zafrir, Gabi

    2016-03-01

    We explore the properties of five-dimensional supersymmetric gauge theories living on 5-brane webs in orientifold 5-plane backgrounds. This allows constructing quiver gauge theories with alternating USp(2 N) and SO(N) gauge groups with fundamental matter, and thus leads to the existence of new 5 d fixed point theories. The web description can be further used to study non-perturbative phenomena such as enhancement of symmetry and duality. We further suggest that one can use these systems to engineer 5 d SO group with spinor matter. We present evidence for this claim.

  8. Multiple M2-Branes and Plane Waves

    OpenAIRE

    Blau, Matthias; O'Loughlin, Martin

    2008-01-01

    We propose a natural generalisation of the BLG multiple M2-brane action to membranes in curved plane wave backgrounds, and verify in two different ways that the action correctly captures the non-trivial space-time geometry. We show that the M2 to D2 reduction of the theory along a non-trivial direction in field space is equivalent to the D2-brane world-volume Yang-Mills theory with a non-trivial (null-time dependent) dilaton in the corresponding IIA background geometry. As another consistency...

  9. New plastic plane stress model for concrete

    International Nuclear Information System (INIS)

    In the paper a description of concrete behaviour in the plane stress case is given on the basis of the modified bounding surface plasticity theory. Three independent plastic mechanisms have been introduced describing axiatoric and deviatoric plastic strains and their coupling. All the new analytical formulae for material functions being in agreement with experiments and loading/unloading criteria have been proposed. In addition, for the proper description of concrete behaviour in tension a new, separate function of bounding surface shrinkage has been introduced. (author)

  10. Plane partitions with 2-periodic weights

    OpenAIRE

    Mkrtchyan, Sevak

    2013-01-01

    We study scaling limits of skew plane partitions with periodic weights under several boundary conditions. We compute the correlation kernel of the limiting point process in the bulk and near turning points on the frozen boundary. The turning points that appear in the homogeneous case split in our model into pairs of turning points macroscopically separated by a "semi-frozen" region. As a result the point process at a turning point is not the GUE minor process, but rather a pair of GUE minor p...

  11. Linear Forced In-Plane and Out-of Plane Vibrations of Frames Having a Curved Member

    OpenAIRE

    Özyiğit, H. A.; Öz, H. R.; Tekelioğlu, M.

    2004-01-01

    The forced, in-plane and out-of-plane vibrations of frames comprised of straight and curved members are investigated using Finite Element Methods. The straight and curved beams are assumed as Euler-Bernoulli type and they have circular cross-sections.  The frame lies in a single plane. In the analysis, elongation, bending and rotary inertia effects are included. Four degrees of freedom for in-plane vibrations and three degrees of freedom for out-of-plane vibrations are assumed. The in-plane a...

  12. ARC Code TI: X-Plane Communications Toolbox (XPC)

    Data.gov (United States)

    National Aeronautics and Space Administration — The X-Plane Communications Toolbox (XPC) is an open source research tool used to interact with the commercial flight simulator software X-Plane. XPC allows users to...

  13. Hyperelliptic plane curves of type (d,d-2)

    OpenAIRE

    Sakai, Fumio; Saleem, Mohammad; Tono, Keita

    2008-01-01

    In a previous paper, we classified and constructed all rational plane curves of type (d,d-2). In this paper, we generalize these results to irreducible plane curves of type (d,d-2) with positive genus.

  14. Exact relativistic solution of disordered radiation with plane symmetry

    International Nuclear Information System (INIS)

    An exact solution of Einstein equations corresponding to an equilibrium distribution of disordered electromagnetic radiation with plane symmetry is obtained. This equilibrium is due solely to the gravitational and pressure effects inherent to the radiation. The distribution of radiation is found to be maximum and finite at the plane of symmetry, and to decrease monotonically in directions normal to this plane. The solution tends asymptotically to the static plane symmetric vacuum solution obtained by Levi-Civita. Timelike and null geodesics are discussed

  15. Waveguide Metacouplers for In-Plane Polarimetry

    Science.gov (United States)

    Pors, Anders; Bozhevolnyi, Sergey I.

    2016-06-01

    The state of polarization (SOP) is an inherent property of the vectorial nature of light and a crucial parameter in a wide range of remote sensing applications. Nevertheless, the SOP is rather cumbersome to probe experimentally, as conventional detectors respond only to the intensity of the light, hence losing the phase information between orthogonal vector components. In this work, we propose a type of polarimeter that is compact and well suited for in-plane optical circuitry while allowing for immediate determination of the SOP through simultaneous retrieval of the associated Stokes parameters. The polarimeter is based on plasmonic phase-gradient birefringent metasurfaces that facilitate normal incident light to launch in-plane photonic-waveguide modes propagating in six predefined directions with the coupling efficiencies providing a direct measure of the incident SOP. The functionality and accuracy of the polarimeter, which essentially is an all-polarization-sensitive waveguide metacoupler, is confirmed through full-wave simulations at the operation wavelength of 1.55 μ m .

  16. The hybrid solution for the Fundamental Plane

    CERN Document Server

    D'Onofrio, M; Moretti, A; Marziani, P; Bindoni, D; Fritz, J; Varela, J; Bettoni, D; Cava, A; Poggianti, B M; Gullieuszik, M; Kjaergaard, P; Moles, M; Vulcani, B; Omizzolo, A; Couch, W J; Dressler, A

    2013-01-01

    By exploiting the database of early-type galaxies (ETGs) members of the WINGS survey of nearby clusters, we address here the long debated question of the origin and shape of the Fundamental Plane (FP). Our data suggest that different physical mechanisms concur in shaping and tilting the FP with respect to the virial plane (VP) expectation. In particular, an hybrid solution in which the structure of galaxies and their stellar population are the main contributors to the FP tilt seems to be favoured. We find that the bulk of the tilt should be attributed to structural non-homology, while stellar population effects play an important but less crucial role. Our data indicate that the differential FP tilt between the V and K-band is due to a sort of entanglement between structural and stellar population effects, for which the inward steepening of color profiles (V-K) tends to increase at increasing the stellar mass of ETGs. The same analysis applied to the ATLAS3D and SDSS data in common with WINGS (WSDSS throughout...

  17. Object tracking based on bit-planes

    Science.gov (United States)

    Li, Na; Zhao, Xiangmo; Liu, Ying; Li, Daxiang; Wu, Shiqian; Zhao, Feng

    2016-01-01

    Visual object tracking is one of the most important components in computer vision. The main challenge for robust tracking is to handle illumination change, appearance modification, occlusion, motion blur, and pose variation. But in surveillance videos, factors such as low resolution, high levels of noise, and uneven illumination further increase the difficulty of tracking. To tackle this problem, an object tracking algorithm based on bit-planes is proposed. First, intensity and local binary pattern features represented by bit-planes are used to build two appearance models, respectively. Second, in the neighborhood of the estimated object location, a region that is most similar to the models is detected as the tracked object in the current frame. In the last step, the appearance models are updated with new tracking results in order to deal with environmental and object changes. Experimental results on several challenging video sequences demonstrate the superior performance of our tracker compared with six state-of-the-art tracking algorithms. Additionally, our tracker is more robust to low resolution, uneven illumination, and noisy video sequences.

  18. Multiple M2-branes and plane waves

    International Nuclear Information System (INIS)

    We propose a natural generalisation of the BLG multiple M2-brane action to membranes in curved plane wave backgrounds, and verify in two different ways that the action correctly captures the non-trivial space-time geometry. We show that the M2 to D2 reduction of the theory along a non-trivial direction in field space is equivalent to the D2-brane world-volume Yang-Mills theory with a non-trivial (null-time dependent) dilaton in the corresponding IIA background geometry. As another consistency check of this proposal we show that the properties of metric 3-algebras ensure the equivalence of the Rosen coordinate version of this action (time-dependent metric on the space of 3-algebra valued scalar fields, no mass terms) and its Brinkmann counterpart (constant couplings but time-dependent mass terms). We also establish an analogous result for deformed Yang-Mills theories in any dimension which, in particular, demonstrates the equivalence of the Rosen and Brinkmann forms of the plane wave matrix string action.

  19. Multiple M2-Branes and Plane Waves

    CERN Document Server

    Blau, Matthias

    2008-01-01

    We propose a natural generalisation of the BLG multiple M2-brane action to membranes in curved plane wave backgrounds, and verify in two different ways that the action correctly captures the non-trivial space-time geometry. We show that the M2 to D2 reduction of the theory along a non-trivial direction in field space is equivalent to the D2-brane worldvolume Yang-Mills theory with a non-trivial (null-time dependent) dilaton in the corresponding IIA background geometry. As another consistency check of this proposal we show that the properties of metric 3-algebras ensure the equivalence of the Rosen coordinate version of this action (time-dependent metric on the space of 3-algebra valued scalar fields, no mass terms) and its Brinkmann counterpart (constant couplings but time-dependent mass terms). We also establish an analogous result for deformed Yang-Mills theories in any dimension which, in particular, demonstrates the equivalence of the Rosen and Brinkmann forms of the plane wave matrix string action.

  20. Weighted norm inequalities for k-plane transforms

    OpenAIRE

    Rubin, Boris

    2012-01-01

    We obtain sharp inequalities for the k-plane transform, the "j-plane to k-plane" transform, and the corresponding dual transforms, acting on $L^p$ spaces with a radial power weight. The operator norms are explicitly evaluated. Some generalizations and open problems are discussed.

  1. Plane Transformations in a Complex Setting II: Isometries

    Science.gov (United States)

    Dana-Picard, Thierry

    2007-01-01

    This paper is the second part of a study of plane transformations using a complex setting. The first part was devoted to homotheties and translations, now attention is turned towards plane isometries. The group theoretic properties of plane isometries are easy to derive and images of classical geometrical objects by these transformations are…

  2. Multispectral linear array (MLA) focal plane mechanical and thermal design

    Science.gov (United States)

    Mitchell, A. S.; Kaminski, E. F.

    1982-01-01

    The mechanical and thermal design of an integrated focal plane subsystem of a Multispectral Linear Array (MLA) instrument is discussed in terms of focal-plane alignment, thermoelastic performance, and thermal requirements. The modular construction and thermal control of the focal plane array are discussed.

  3. l482np.m77t - MGD77 data file for Geophysical data from field activity L-4-82-NP in Low-energy abyssal hill areas midway between San Franciso and Hawaii from 03/01/1982 to 03/15/1982

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Single-beam bathymetry, gravity, and magnetic data along with DGPS navigation data was collected as part of field activity L-4-82-NP in Low-energy abyssal hill...

  4. Error Analysis on Plane-to-Plane Linear Approximate Coordinate Transformation

    Indian Academy of Sciences (India)

    Q. F. Zhang; Q. Y. Peng; J. H. Fan

    2014-09-01

    In this paper, the error analysis has been done for the linear approximate transformation between two tangent planes in celestial sphere in a simple case. The results demonstrate that the error from the linear transformation does not meet the requirement of high-precision astrometry under some conditions, so the linear approximate transformation should be taken seriously.

  5. Design of an interface between the smart grid control plane and the telecommunications network control plane / data center control plan

    OpenAIRE

    Mugisa, Justine

    2014-01-01

    In an effort to reduce the energy costs and carbon foot print of the ICT industry, with focus on the Telecommunications Network and Data Center Networks we study the design of an interface between the Smart Grid control plane and the Telecommunications Network Control Plane/Data Center Control Plane

  6. Point Charge Dynamics Near a Grounded Conducting Plane

    OpenAIRE

    Haglin, Kevin L.

    2010-01-01

    The classic image problem in electromagnetism involves a grounded infinite conducting plane and a point charge. The force of attraction between the point charge and the plane is identified using an equivalent-field picture of an image charge with opposite sign equidistant behind the plane resulting in a 1/{\\it r}$^{\\rm 2}$ force of attraction between the original charge and the plane. If the point charge is released from rest it will reach the plane in a time $\\tau$. This time $\\tau$ has not ...

  7. Landau levels on the hyperbolic plane

    Energy Technology Data Exchange (ETDEWEB)

    Fakhri, H [Institute for Studies in Theoretical Physics and Mathematics (IPM), Tehran 19395-5531 (Iran, Islamic Republic of); Shariati, M [Department of Physics, Khajeh Nassir-Al-Deen Toosi University of Technology, Tehran 15418 (Iran, Islamic Republic of)

    2004-11-05

    The quantum states of a spinless charged particle on a hyperbolic plane in the presence of a uniform magnetic field with a generalized quantization condition are proved to be the bases of the irreducible Hilbert representation spaces of the Lie algebra u(1, 1). The dynamical symmetry group U(1, 1) with the explicit form of the Lie algebra generators is extracted. It is also shown that the energy has an infinite-fold degeneracy in each of the representation spaces which are allocated to the different values of the magnetic field strength. Based on the simultaneous shift of two parameters, it is also noted that the quantum states realize the representations of Lie algebra u(2) by shifting the magnetic field strength. (letter to the editor)

  8. Landau levels on the hyperbolic plane

    International Nuclear Information System (INIS)

    The quantum states of a spinless charged particle on a hyperbolic plane in the presence of a uniform magnetic field with a generalized quantization condition are proved to be the bases of the irreducible Hilbert representation spaces of the Lie algebra u(1, 1). The dynamical symmetry group U(1, 1) with the explicit form of the Lie algebra generators is extracted. It is also shown that the energy has an infinite-fold degeneracy in each of the representation spaces which are allocated to the different values of the magnetic field strength. Based on the simultaneous shift of two parameters, it is also noted that the quantum states realize the representations of Lie algebra u(2) by shifting the magnetic field strength. (letter to the editor)

  9. Smart trigger logic for focal plane arrays

    Science.gov (United States)

    Levy, James E; Campbell, David V; Holmes, Michael L; Lovejoy, Robert; Wojciechowski, Kenneth; Kay, Randolph R; Cavanaugh, William S; Gurrieri, Thomas M

    2014-03-25

    An electronic device includes a memory configured to receive data representing light intensity values from pixels in a focal plane array and a processor that analyzes the received data to determine which light values correspond to triggered pixels, where the triggered pixels are those pixels that meet a predefined set of criteria, and determines, for each triggered pixel, a set of neighbor pixels for which light intensity values are to be stored. The electronic device also includes a buffer that temporarily stores light intensity values for at least one previously processed row of pixels, so that when a triggered pixel is identified in a current row, light intensity values for the neighbor pixels in the previously processed row and for the triggered pixel are persistently stored, as well as a data transmitter that transmits the persistently stored light intensity values for the triggered and neighbor pixels to a data receiver.

  10. On inner constraints in plane circular arches

    Energy Technology Data Exchange (ETDEWEB)

    Ruta, G.C. [Universita di Roma ' ' La Sapienza' ' , Dipartimento di Ingegneria Strutturale e Geotecnica, via Eudossiana 18, I-00184 Roma (Italy)

    2004-12-01

    A one-dimensional model of plane circular arches with rigid sections is introduced. Suitable strain measures are defined as deviations from rigid displacements. If the arch is thin, constitutive arguments make the shearing strain negligible. Hence, the shearing indeformability will be assumed as inner constraint. By means of a formal power series expansion of the exact measures of deformation it is shown that the shearing indeformability implies some constraints on the axial strain. In particular, the first-order axial strain must vanish in the case of infinitesimal displacements. The same procedure is applied to pure flexible arches, in order to compare the two sets of results. It is shown that the hypothesis of finite pure flexibility is not compatible with small deformations of the arch. An example is provided to evaluate the effects of the two constraints at the first non-linear step of the perturbation expansions. (orig.)

  11. Beta-plane turbulence: experiments with altimetry

    CERN Document Server

    Zhang, Y

    2013-01-01

    Results from a new series of experiments on flows generated by an electromagnetic method in a rotating tank with topographic beta-effect are presented. The velocity fields are measured by the Altimetric Imaging Velocimetry. The turbulent flows observed in the experiments develop zonal jets which are latent in a stationary forced-dissipative regime of the flow but become prominent in the decaying flow. The two-dimensional energy spectra of the flows exhibit the development of anisotropy towards zonal motions. The experiments demonstrate dual turbulent cascade with energy and enstrophy ranges. The frequency-wavenumber spectra reveal the presence of Rossby waves at low wavenumbers which are excited by the turbulent motions. The experimental results are compared with available theory of beta-plane turbulence.

  12. Plane posets, special posets, and permutations

    CERN Document Server

    Foissy, Loïc

    2011-01-01

    We study the self-dual Hopf algebra $\\h_{\\SP}$ of special posets introduced by Malvenuto and Reutenauer and the Hopf algebra morphism from $\\h_{\\SP}$ to to the Hopf algebra of free quasi-symmetric functions $\\FQSym$ given by linear extensions. In particular, we construct two Hopf subalgebras both isomorphic to $\\FQSym$; the first one is based on plane posets, the second one on heap-ordered forests. An explicit isomorphism between these two Hopf subalgebras is also defined with the help of two transformations on special posets. The restriction of the Hopf pairing of $\\h_{\\SP}$ to these Hopf subalgebras and others is also studied, as well as certain isometries between them. These problems are solved using duplicial and dendriform structures.

  13. Magnetic measurements with atomic-plane resolution.

    Science.gov (United States)

    Rusz, Ján; Muto, Shunsuke; Spiegelberg, Jakob; Adam, Roman; Tatsumi, Kazuyoshi; Bürgler, Daniel E; Oppeneer, Peter M; Schneider, Claus M

    2016-01-01

    Rapid development of magnetic nanotechnologies calls for experimental techniques capable of providing magnetic information with subnanometre spatial resolution. Available probes of magnetism either detect only surface properties, such as spin-polarized scanning tunnelling microscopy, magnetic force microscopy or spin-polarized low-energy electron microscopy, or they are bulk probes with limited spatial resolution or quantitativeness, such as X-ray magnetic circular dichroism or classical electron magnetic circular dichroism (EMCD). Atomic resolution EMCD methods have been proposed, although not yet experimentally realized. Here, we demonstrate an EMCD technique with an atomic size electron probe utilizing a probe-corrected scanning transmission electron microscope in its standard operation mode. The crucial element of the method is a ramp in the phase of the electron beam wavefunction, introduced by a controlled beam displacement. We detect EMCD signals with atomic-plane resolution, thereby bringing near-atomic resolution magnetic circular dichroism spectroscopy to hundreds of laboratories worldwide. PMID:27578421

  14. Plane shock wave studies of geologic media

    International Nuclear Information System (INIS)

    Plane shock wave experiments have been conducted on eight geologic materials in an effort to determine the importance of time-dependent mechanical behavior. Of the eight rocks studied, only Westerly granite and nugget sandstone appear to show time independence. In the slightly porous materials (1-5 percent), Blair dolomite and sodium chloride, and in the highly porous (15 to 40 percent) rock, Mt. Helen tuff and Indiana limestone, time-dependent behavior is associated with the time required to close the available porosity. In water-saturated rocks the time dependence arises because the water that is present shows no indication of transformation to the higher pressure ice phases, thus suggesting the possibility that a metastable form of water exists under dynamic conditions

  15. Infrared focal plane array crosstalk measurement

    Science.gov (United States)

    Dang, Khoa V.; Kauffman, Christopher L.; Derzko, Zenon I.

    1992-07-01

    Crosstalk between two neighboring elements in a focal plane array (FPA) occurs when signal incident on one element in the array is seen on another. This undesired effect can occur due to both the electrical and optical properties of the FPA. An effort is underway at the U.S. Army's Night Vision and Electro-Optics Directorate to develop a capability to measure crosstalk on both mid-wave infrared and long-wave infrared FPAs. A single detector in an array is illuminated using a laser source coupled with a beam expander, collimating lens, and focusing lens. The relative response of that detector to that of its neighboring detectors is measured to calculate crosstalk. The various components of the test station, the methodology for implementing the crosstalk measurement, and a model of the laser spot size are discussed.

  16. Coincidence lattices in the hyperbolic plane.

    Science.gov (United States)

    Rodríguez-Andrade, M A; Aragón-González, G; Aragón, J L; Gómez-Rodríguez, A

    2011-01-01

    The problem of coincidences of lattices in the space R(p,q), with p + q = 2, is analyzed using Clifford algebra. We show that, as in R(n), any coincidence isometry can be decomposed as a product of at most two reflections by vectors of the lattice. Bases and coincidence indices are constructed explicitly for several interesting lattices. Our procedure is metric-independent and, in particular, the hyperbolic plane is obtained when p = q = 1. Additionally, we provide a proof of the Cartan-Dieudonné theorem for R(p,q), with p + q = 2, that includes an algorithm to decompose an orthogonal transformation into a product of reflections. PMID:21173471

  17. Unsteady granular flows down an inclined plane

    Science.gov (United States)

    Parez, Stanislav; Aharonov, Einat; Toussaint, Renaud

    2016-04-01

    The continuum description of granular flows is still a challenge despite their importance in many geophysical and industrial applications. We extend previous works, which have explored steady flow properties, by focusing on unsteady flows accelerating or decelerating down an inclined plane in the simple shear configuration. We solve the flow kinematics analytically, including predictions of evolving velocity and stress profiles and the duration of the transient stage. The solution shows why and how granular materials reach steady flow on slopes steeper than the angle of repose and how they decelerate on shallower slopes. The model might facilitate development of natural hazard assessment and may be modified in the future to explore unsteady granular flows in different configurations.

  18. Hubble Views Saturn Ring-Plane Crossing

    Science.gov (United States)

    1995-01-01

    This sequence of images from NASA's Hubble Space Telescope documents a rare astronomical alignment -- Saturn's magnificent ring system turned edge-on. This occurs when the Earth passes through Saturn's ring plane, as it does approximately every 15 years.These pictures were taken with Hubble's Wide Field Planetary Camera 2 on 22 May 1995, when Saturn was at a distance of 919 million miles (1.5 billion kilometers) from Earth. At Saturn, Hubble can see details as small as 450 miles (725 km) across. In each image, the dark band across Saturn is the ring shadow cast by the Sun which is still 2.7 degrees above Saturn's ring plane. The box around the western portion of the rings (to the right of Saturn) in each image indicates the area in which the faint light from the rings has been multiplied through image processing (by a factor of 25) to make the rings more visible.[Top] -This image was taken while the Earth was above the lit face of the rings. The moons Tethys and Dione are visible to the east (left) of Saturn; Janus is the bright spot near the center of the ring portion in the box, and Pandora is faintly visible just inside the left edge of this box. Saturn's atmosphere shows remarkable detail: multiple banding in both the northern and southern hemispheres, wispy structure at the north edge of the equatorial zone, and a bright area above the ring shadow that is caused by sunlight scattered off the rings onto the atmosphere. There is evidence of a faint polar haze over the north pole of Saturn and a fainter haze over the south.[Center] -This image was taken close to the time of ring-plane crossing. The rings are 75% fainter than in the top image, though they do not disappear completely because the vertical face of the rings still reflects sunlight when the rings are edge-on. Rhea is visible to the east of Saturn, Enceladus is the bright satellite in the rings to the west, and Janus is the fainter blip to its right. Pandora is just to the left of Enceladus, but is not

  19. Paleoceanographic interpretations of late Pleistocene to Holocene sedimentological and geochemical proxy-data from SE-Atlantic abyssal plains (Cape, Angola and Guinea Basin)

    Science.gov (United States)

    Piller, W. E.; Müllegger, S.

    2009-04-01

    Sediments of the deep abyssal regions of the Southeast Atlantic (Cape Basin, Angola Basin and Guinea Basin) were studied to reconstruct changes in surface and deep water circulation, bioproductivity, and terrigenous sediment flux. To gain these results various sedimentological and geochemical proxies were imposed, including grain size data, foraminiferal fragmentation, carbonate and organic carbon content, as well as stable oxygen and carbon isotope contents of foraminiferal tests. Samples were gained with a multicorer device during Meteor cruise 63/2 (2005) in water depths between ~5,100 and ~5,600 m. The superficial 30 cm of sediment, sampled in 1/2, 1 and 5 cm steps, were processed for this study. The record covers parts of the Pleistocene and Holocene. Even if the sedimentation conditions seem to be similar in the deep-sea regions of the SE-Atlantic there are clear differences between the three sampled locations. This is caused by major changes in deep water corrosiveness leading to fluctuations in the sedimentation rate and carbonate preservation. Cape Basin localities show a pattern of enhanced carbonate preservation around 12 ka BP possibly indicating a delayed Last Glacial Maximum signal. This pattern, which is typical for Indo-Pacific records, clearly points to an influence of Antarctic Bottom Water (AABW) at water depths below 5000 m in the Northern Cape Basin. The non-correlation between carbonate content and grain size distribution is owing to a coccoliths' dominated carbonate production possibly caused by low nutrient availability in surface waters and the higher dissolution susceptibility of foraminiferal tests. Angola Basin samples delivered highest sand contents, a carbonate peak and low organic carbon values around 8.2 ka BP which indicate a reduced bioproduction and nutrient supply in superficial waters. A connection of the 8.2 ka cold event in the northern hemisphere and central African precipitation, equatorial East Atlantic (EEA) upwelling

  20. Fe-bearing Olenite with Tetrahedrally Coordinated Al from an Abyssal Pegmatite at Kutna Hora, Czech Republic: Structure, Crystal Chemistry, Optical and XANES Spectra

    International Nuclear Information System (INIS)

    The pale blue rim of olenite on a black crystal of olenite-schorl tourmaline from an abyssal pegmatite at the locality Kuklik, near Kutna Hora, Czech Republic, has been chemically and structurally characterized. The optimized formula, calculated using chemical and structural data, is X(Na0.54Ca0.14K0.01(D'Alembertian)0.31)Y(Al2.15Fe2+0.06Ti4+0.01) Z(Al5.90Mg0.10) T(Si5.60Al0.40)B3O27V[(OH)2.49O0.51] W(O0.99F0.01), with α 15.8838(3), c 7.1056(2) (angstrom) and R = 0.017. The relatively short bond-length, 1.992 (angstrom), confirms the high content of Al at the Y site (∼2.1 atoms per formula unit, apfu). It is similar to that of olenite from the type locality, though the olenite from Kuklik contains significant amounts of Fe at the Y site, and significant amounts of [4]Al (∼0.4 apfu) instead of [4]B in the T site. This finding is supported by results of the structure determination, which show an enlarged bond-length of ∼1.626 (angstrom). This sample of olenite shows that nonstoichiometric content of Si does not always imply [4]B in aluminous tourmaline. No H could be found at the O1 site by refinement, and the spherical distribution of electron density in the difference-Fourier map around the O1 site supports the conclusion that this site is only or mainly occupied by O and not by OH. On a bond-angle distortion (σoct2 of the ZO6 octahedron) - distance diagram, the olenite from Kuklik lies between compositions containing 3 (OH) at the V site, and natural buergerite, which contains 0.3 (OH) and 2.7 O at the V site (O3 site). The (OH) content with ∼2.5 (OH) pfu, which was calculated for a charge-balanced formula, is in a good agreement with these findings and with the integrated intensity of the OH overtones in the 7000 cm-1 region (690 cm-2 per cm thickness), which is one of the lowest measured to date for tourmaline. The OH seems to be ordered strongly at the O3 site. The composition of this sample of olenite shows a trend toward the proposed olenite end

  1. The effect of prior out-of-plane damage on the in-plane behavior of unreinforced masonary infilled frames

    International Nuclear Information System (INIS)

    In order to address the effect of prior out-of-plane damage on the in-plane behavior of unreinforced masonry infills, two full-scale (24 feet tall by 28 feet long) structural clay tile infills and one frame-only (no infilling) were constructed and tested. The infilled frame, consisting of two wide flange columns surrounded by masonry pilasters and an eccentric wide flange purlin, was identical to many of the infills located at the Oak Ridge Y-12 Plant. The masonry infill was approximately 12.5 inches thick and was composed of individual four- and eight-inch hollow clay tile (HCT) units. One of the infill panels was tested out-of-plane by four quasi-static actuators - two on each column. The test structure was deflected out-of-plane equally at all four actuator locations in order to simulate the computed deflection path of the top and bottom chords of a roof truss framing into the columns at these locations. Prior to the infill testing, a bare frame was loaded similarly in order to determine the behavior and stiffness contribution of the frame only. Following the out-of-plane test of the infilled panel, the structure was loaded in-plane to failure in order to ascertain residual strength. A second, identical infilled frame was then constructed and tested in-plane to failure. In this way, in-plane behavior with and without prior out-of-plane damage could be established and compared. For both out-of-plane and in-plane testing, reversed-cyclic quasi-static loading was used in order to obtain full tension/compression hystereses. Also, natural frequencies of the first infilled panel were determined before and after the out-of-plane testing. This paper describes the test series and discusses the conclusions pertinent to the effect of out-of-plane cracking on in-plane stiffness and behavior

  2. Plane section of cone and cylinder in computer geometry

    Directory of Open Access Journals (Sweden)

    Obradović Ratko M.

    2005-01-01

    Full Text Available In this paper a mathematical apparatus for determination of plane section of cone and cylinder was formed. By using the descriptive geometric approach the contour lines of these quadrics were determined. The fact that the tangent lines of a circle could be transformed to the tangent lines of an ellipse using affinity was employed. In that way surfaces are represented by contour lines (tangent lines of basic ellipse in oblique projection and thus they have a realistic view. Intersecting plane α is a plane normal to a frontal plane. For determination of intersecting points of intersecting curve between the plane α and the quadrics, the lock of auxiliary planes, which contain the vertex of quadrics, was used. Each auxiliary plane from the observed lock intersect the surface in two lines which intersect the given plane α in two points. By using a sufficient number of auxiliary planes the intersecting curve as a set of pairs of points for all auxiliary planes is determined and the intersecting curve was drawn by lightening of these pairs of points on the graphical screen.

  3. Interactive visualizations of blowups of the plane.

    Science.gov (United States)

    Schenzel, Peter; Stussak, Christian

    2013-06-01

    Blowups are an important technique in algebraic geometry that permit the smoothing of singular algebraic varieties. It is a challenge to visualize this process even in the case of blowups of points X in the affine plane AA(IR)(2). First results were obtained by Brodmann with the aid of the so-called toroidal blowup, a compact embedding of the blowup into affine 3-space. In fact, Brodmann provides a rational parametrization of the toroidal blowup, but its visualization fails in the neighborhood of X because the parametrization tends to indefinite terms of the form 0/0. Our approach is based on implicitization of the parametric form. By methods from commutative algebra we are able to reduce the implicitization to the computation of a single, fairly simple resultant. This provides an algebraic equation of the implicit surface of the toroidal blowup including the so-called exceptional fiber associated with X. Surprisingly, the degree of the equation grows only linearly with the degree of the parametrization. By applying additional clipping techniques to the implicit surface we are able to visualize the toroidal blowup as well as its deformations by several parameters interactively in real time using GPU-based ray casting techniques. The methods of the paper provide insights in the structure of blowups of points, even if the points are interactively moved or tend to degenerations. PMID:22802122

  4. Hybrid inflation in the complex plane

    International Nuclear Information System (INIS)

    Supersymmetric hybrid inflation is an exquisite framework to connect inflationary cosmology to particle physics at the scale of grand unification. Ending in a phase transition associated with spontaneous symmetry breaking, it can naturally explain the generation of entropy, matter and dark matter. Coupling F-term hybrid inflation to soft supersymmetry breaking distorts the rotational invariance in the complex inflaton plane - an important fact, which has been neglected in all previous studies. Based on the δN formalism, we analyze the cosmological perturbations for the first time in the full two-field model, also taking into account the fast-roll dynamics at and after the end of inflation. As a consequence of the two-field nature of hybrid inflation, the predictions for the primordial fluctuations depend not only on the parameters of the Lagrangian, but are eventually fixed by the choice of the inflationary trajectory. Recognizing hybrid inflation as a two-field model resolves two shortcomings often times attributed to it: The fine-tuning problem of the initial conditions is greatly relaxed and a spectral index in accordance with the PLANCK data can be achieved in a large part of the parameter space without the aid of supergravity corrections. Our analysis can be easily generalized to other (including large-field) scenarios of inflation in which soft supersymmetry breaking transforms an initially single-field model into a multi-field model.

  5. Hybrid inflation in the complex plane

    International Nuclear Information System (INIS)

    Supersymmetric hybrid inflation is an exquisite framework to connect inflationary cosmology to particle physics at the scale of grand unification. Ending in a phase transition associated with spontaneous symmetry breaking, it can naturally explain the generation of entropy, matter and dark matter. Coupling F-term hybrid inflation to soft supersymmetry breaking distorts the rotational invariance in the complex inflaton plane — an important fact, which has been neglected in all previous studies. Based on the δ N formalism, we analyze the cosmological perturbations for the first time in the full two-field model, also taking into account the fast-roll dynamics at and after the end of inflation. As a consequence of the two-field nature of hybrid inflation, the predictions for the primordial fluctuations depend not only on the parameters of the Lagrangian, but are eventually fixed by the choice of the inflationary trajectory. Recognizing hybrid inflation as a two-field model resolves two shortcomings often times attributed to it: the fine-tuning problem of the initial conditions is greatly relaxed and a spectral index in accordance with the PLANCK data can be achieved in a large part of the parameter space without the aid of supergravity corrections. Our analysis can be easily generalized to other (including large-field) scenarios of inflation in which soft supersymmetry breaking transforms an initially single-field model into a multi-field model

  6. Circular Vibration Planing of Inconel 718

    Science.gov (United States)

    Hettiarachchi, Nandita Kalyanakumara; Moriwaki, Toshimichi; Shibasaka, Toshiro; Nakamoto, Keiichi

    Circular vibration milling (CVM) is achieved by vibrating a milling cutter about the machine tool spindle axis in a circular path, in addition to its rotary motion. CVM has been proven capable of producing better surface finishes on difficult to cut materials. However, the CVM process is far slower than conventional milling process. In circular vibration planing (CVP) process, the cutting tool is clamped without rotation and fed at a speed comparable to the feed speed of conventional milling. By superimposing circular vibration motion, necessary cutting speed could be achieved keeping the feed speed at realistic values. Inconel 718 was machined by CVP and conventional milling at a similar feed rate. It was observed that CVP could reduce tool wear and hence produce better surface finishes than conventional milling. A geometric simulation showed a major difference between uncut chip shapes of the two processes. The difference of uncut chip shapes suggests that in CVP process, less rubbing occurs between tool flank face and work before the tool penetrates in to the work to form a chip. The reduced rubbing of the flank face is proposed as the reson for reduced tool wear in CVP when compared with conventional milling.

  7. YAP (Ce) as focal plane detectors

    International Nuclear Information System (INIS)

    YAP (Ce) has been known to be one of the commercially available new scintillators that can be used for several applications. It has a good timing response and a very high value for the radiation hardness, compared to other known inorganic scintillators. Several studies have been reported on the properties of the scintillator, viz., light yield, decay time constant, gamma and charged particle response, pulse shape discrimination and timing characteristics. The YAP(Ce) crystals has a very good response to the energetic heavy ions and attempts have been made to employ it as a viable alternative to the Si detectors for the detection of heavy ions. As a part of the experimental facilities, being developed for the upcoming Superconducting cyclotron at VECC, the possibility is being explored for using the YAP(Ce) as an E detector, preceded by a position sensitive MWPCs as αE counterpart, at the focal plane of the proposed superconducting solenoid spectrometer. The selection of Photo Multiplier Tubes (PMT) has been very crucial in such cases in order to have good timing response and energy resolution for energetic heavy ions. The responses have been tested for different bias voltages of the tube and the best values have been reported here

  8. The Mopra Southern Galactic Plane CO Survey

    CERN Document Server

    Burton, Michael; Glueck, Christian; Goldsmith, Paul; Hawkes, Jarryd; Hollenbach, David; Kulesa, Craig; Martin, Chris; Pineda, Jorge; Rowell, Gavin; Simon, Robert; Stark, Tony; Stutzki, Juergen; Tothill, Nick; Urquhart, James; Walker, Chris; Walsh, Andrew; Wolfire, Mark

    2013-01-01

    We present the first results from a new carbon monoxide (CO) survey of the southern Galactic plane being conducted with the Mopra radio telescope in Australia. The 12CO, 13CO and C18O J=1-0 lines are being mapped over the l = 305-345 deg, b = +/- 0.5 deg portion of the 4th quadrant of the Galaxy, at 35" spatial and 0.1 km/s spectral resolution. The survey is being undertaken with two principal science objectives: (i) to determine where and how molecular clouds are forming in the Galaxy and (ii) to probe the connection between molecular clouds and the "missing" gas inferred from gamma-ray observations. We describe the motivation for the survey, the instrumentation and observing techniques being applied, and the data reduction and analysis methodology. In this paper we present the data from the first degree surveyed, l = 323-324 deg, b = +/- 0.5 deg. We compare the data to the previous CO survey of this region and present metrics quantifying the performance being achieved; the rms sensitivity per 0.1 km/s veloc...

  9. Elasticplastic discs under plane stress conditions

    CERN Document Server

    Alexandrov, Sergey

    2015-01-01

    This Volume presents a unified approach to calculate the plane stress distribution of stress and strain in thin elastic/plastic discs subject to various loading conditions. There is a vast amount of literature on analytical and semi-analytical solutions for such discs obeying Tresca’s yield criterion and its associated flow rule. On the other hand, most of analytical and semi-analytical solutions for Mises yield criterion are based on the deformation theory of plasticity. A distinguished feature of the solutions given in the present volume is that the flow theory of plasticity and Mises yield criterion are adopted. The solutions are semi-analytical in the sense that numerical methods are only necessary to evaluate ordinary integrals and solve transcendental equations. The book shows that under certain conditions solutions based on the deformation and flow theories of plasticity coincide. All the solutions are illustrated with numerical examples. The goal of the book is to provide the reader with a vision an...

  10. Quantum dynamics of a plane pendulum

    International Nuclear Information System (INIS)

    A semianalytical approach to the quantum dynamics of a plane pendulum is developed, based on Mathieu functions which appear as stationary wave functions. The time-dependent Schroedinger equation is solved for pendular analogs of coherent and squeezed states of a harmonic oscillator, induced by instantaneous changes of the periodic potential energy function. Coherent pendular states are discussed between the harmonic limit for small displacements and the inverted pendulum limit, while squeezed pendular states are shown to interpolate between vibrational and free rotational motion. In the latter case, full and fractional revivals as well as spatiotemporal structures in the time evolution of the probability densities (quantum carpets) are quantitatively analyzed. Corresponding expressions for the mean orientation are derived in terms of Mathieu functions in time. For periodic double well potentials, different revival schemes, and different quantum carpets are found for the even and odd initial states forming the ground tunneling doublet. Time evolution of the mean alignment allows the separation of states with different parity. Implications for external (rotational) and internal (torsional) motion of molecules induced by intense laser fields are discussed.

  11. Collaborative Search on the Plane without Communication

    CERN Document Server

    Feinerman, Ofer; Lotker, Zvi; Sereni, Jean-Sébastien

    2012-01-01

    We use distributed computing tools to provide a new perspective on the behavior of cooperative biological ensembles. We introduce the Ants Nearby Treasure Search (ANTS) problem, a generalization of the classical cow-path problem, which is relevant for collective foraging in animal groups. In the ANTS problem, k identical (probabilistic) agents, initially placed at some central location, collectively search for a treasure in the two-dimensional plane. The treasure is placed at a target location by an adversary and the goal is to find it as fast as possible as a function of both k and D, where D is the distance between the central location and the target. This is biologically motivated by cooperative, central place foraging, such as performed by ants around their nest. In this type of search there is a strong preference to locate nearby food sources before those that are further away. We focus on trying to find what can be achieved if communication is limited or altogether absent. Indeed, to avoid overlaps agen...

  12. Counterpropagating Rossby waves in confined plane wakes.

    Science.gov (United States)

    Biancofiore, L; Gallaire, F

    2012-07-01

    In the present work, we revisit the temporal and the spatio-temporal stability of confined plane wakes under the perspective of the counterpropagating Rossby waves (CRWs). Within the context of broken line velocity profiles, each vorticity discontinuity can be associated to a counterpropagating Rossby wave. In the case of a wake modeled by a broken line profile, the interaction of two CRWs is shown to originate in a shear instability. Following this description, we first recover the stability results obtained by Juniper [J. Fluid Mech. 590, 163-185 (2007)]10.1017/S0022112007007975 and Biancofiore and Gallaire [Phys. Fluids 23, 034103 (2011)]10.1063/1.3554764 by means of the classical normal mode analysis. In this manner, we propose an explanation of the stabilizing influence of the confinement on the temporal stability properties. The CRW description further allows us to propose a new interpretation of the counterintuitive spatio-temporal destabilization in wake flows at moderate confinement noticed by Juniper [J. Fluid Mech. 565, 171-195 (2006)]10.1017/S0022112006001558: it is well predicted by the mean group velocity of the uncoupled CRWs. PMID:22865998

  13. Non-crossing Connectors in the Plane

    CERN Document Server

    Kratochvíl, Jan

    2012-01-01

    We consider the non-crossing connectors problem, which is stated as follows: Given n simply connected regions R_1,...,R_n in the plane and finite point sets P_i subset of R_i for i=1,...,n, are there non-crossing connectors y_i for (R_i,P_i), i.e., arc-connected sets y_i with P_i subset of y_i subset of R_i for every i=1,...,n, such that y_i and y_j are disjoint for all i different from j? We prove that non-crossing connectors do always exist if the regions form a collection of pseudo-disks, i.e., the boundaries of every pair of regions intersect at most twice. We provide a simple polynomial-time algorithm if the regions are axis-aligned rectangles. Finally we prove that the general problem is NP-complete, even if the regions are convex, the boundaries of every pair of regions intersect at most four times and P_i consists of only two points on the boundary of R_i for i=1,...,n.

  14. Condensation on a cooled plane upright wall

    International Nuclear Information System (INIS)

    The vapor condensation along a cooled upright plane wall was studied. The theoretical and experimental results obtained in the simple case, give the essential characteristics of the phenomenon of condensation along a cold wall that keeps the vapor apart from the coolant inside a surface condenser. The phenomenon presents two different appearances according as the wall is wetted or not by the liquid. In the first case a continuous liquid film runs down the wall and a conventional Nusselt calculation gives the film thickness and the heat exchange coefficient between a pure saturated vapor and the cold wall. The calculation is developed in detail and the effect of a vapor flow along the film is discussed as well as that of the presence of a noncondensable gas inside the vapor. In the second case, separated liquid drops are formed on the wall, the phenomenon is called ''dropwise condensation'' and the heat exchange coefficients obtained are much higher than with film condensation. The theoretical aspects of the problem are discussed with some experimental results

  15. ORFEUS focal plane instrumentation: The Berkeley spectrometer

    Science.gov (United States)

    Hurwitz, Mark; Bowyer, Stuart

    1988-01-01

    A spectrograph for the ORFEUS mission that incorporates four varied line-space, spherically figured diffraction gratings was designed. The ORFEUS, a 1-m normal incidence telescope is equipped with 2 focal plane spectrographs. The Berkeley spectrograph was developed with an optimizing raytracing computer code. Each grating accepts the light from 20 percent of the aperture of the telescope primary mirror and has a unique set of characteristics to cover a sub-bandpass within the 390 to 1200 A spectral range. Two photon-counting detectors incorporating a time delay readout system are used to record the spectra from all four gratings simultaneously. The nominal design achieves a spectral resolution (FWHM) in excess of 5500 at all wavelengths within the bandpass. The resolution is limited primarily by the detector spatial resolution. The 1 sigma astigmatism of this design varies between 13 and 150 micrometer on the same focal surface. An independent, direct imaging system tracks the drift of the target within the spectrometer aperture and allows measurement of the misalignment between the telescope optical axis and that of the external star tracker. The resolution and astigmatism achievable with this design are superior to those of a standard Rowland spectrograph designed with the same constraints.

  16. Small pixel oversampled IR focal plane arrays

    Science.gov (United States)

    Caulfield, John; Curzan, Jon; Lewis, Jay; Dhar, Nibir

    2015-06-01

    We report on a new high definition high charge capacity 2.1 Mpixel MWIR Infrared Focal Plane Array. This high definition (HD) FPA utilizes a small 5 um pitch pixel size which is below the Nyquist limit imposed by the optical systems Point Spread Function (PSF). These smaller sub diffraction limited pixels allow spatial oversampling of the image. We show that oversampling IRFPAs enables improved fidelity in imaging including resolution improvements, advanced pixel correlation processing to reduce false alarm rates, improved detection ranges, and an improved ability to track closely spaced objects. Small pixel HD arrays are viewed as the key component enabling lower size, power and weight of the IR Sensor System. Small pixels enables a reduction in the size of the systems components from the smaller detector and ROIC array, the reduced optics focal length and overall lens size, resulting in an overall compactness in the sensor package, cooling and associated electronics. The highly sensitive MWIR small pixel HD FPA has the capability to detect dimmer signals at longer ranges than previously demonstrated.

  17. Plane Partitions with Two-Periodic Weights

    Science.gov (United States)

    Mkrtchyan, Sevak

    2014-09-01

    We study scaling limits of skew plane partitions with periodic weights under several boundary conditions. We compute the correlation kernel of the limiting point process in the bulk and near turning points on the frozen boundary. The system develops pairs of turning points (points where three different phases meet), which are separated by "semi-frozen" regions. We show that the point process at such a turning point is a pair of non-trivially correlated GUE minor processes. In the limit when all weights become the same, i.e. in the homogeneous case, such a pair of turning points collapses into a single turning point and the local process becomes the GUE minor process. We also study an intermediate regime when the weights are periodic but all converge to 1. In this regime the limit shape and correlations in the bulk are the same as in the case of homogeneous weights, and periodicity is not visible in the bulk. However, the process at turning points is still not the GUE minor process.

  18. Variable Radio Sources in the Galactic Plane

    CERN Document Server

    Becker, Robert H; White, Richard L; Proctor, Deanne D

    2010-01-01

    Using three epochs of VLA observations of the Galactic Plane in the first quadrant taken ~15 years apart, we have conducted a search for a population of variable Galactic radio emitters in the flux density range 1-100 mJy at 6 cm. We find 39 variable sources in a total survey area of 23.2 sq deg. Correcting for various selection effects and for the extragalactic variable population of active galactic nuclei, we conclude there are ~1.6 Galactic sources per sq deg which vary by more than 50% on a time scale of years (or shorter). We show that these sources are much more highly variable than extragalactic objects; more than 50% show variability by a factor >2 compared to <10% for extragalactic objects in the same flux density range. We also show that the fraction of variable sources increases toward the Galactic center (another indication that this is a Galactic population), and that the spectral indices of many of these sources are flat or inverted. A small number of the variables are coincident with mid-IR ...

  19. Head rotation and sound image localization in the median plane

    Institute of Scientific and Technical Information of China (English)

    RAO Dan; XIE Bosun

    2005-01-01

    The effect of head rotation on median plane sound source (or image) localization is studied. It is suggested that, at low frequency, the change of interaural time difference (ITD) caused by head rotation supplies information for determining sound source direction in the median plane. Based on the suggestion, the summed sound image localization equations for multiple loudspeakers arranged in the median plane are derived. Especially, for a pair of loudspeakers arranged front-back symmetrically in the median plane, the localization equations are similar to that of stereophonic sound in horizontal plane. A sound image localization experiment was carried out to prove the theoretical analysis. The results of this paper are not only available to virtual spatial auditory, but also supply a quantitative validation of the hypothesis that head rotation is a cue for sound source localization in the median plane at low frequency.

  20. Technological development of the OGRE focal plane array

    OpenAIRE

    Tutt, James; McEntaffer, Randall L.; DeRoo, Casey; Schultz, Ted; Rogers, Thomas; Murray, Neil; Holland, Andrew; Weatherill, Daniel; Holland, Karen; Colebrook, David; Farn, David

    2015-01-01

    The Off-plane Grating Rocket Experiment (OGRE) is a high resolution soft X-ray spectrometer sub-orbital rocket payload designed as a technology development platform for three low Technology Readiness Level (TRL) components. The incident photons will be focused using a light-weight, high resolution, single-crystal silicon optic. They are then dispersed conically according to wavelength by an array of off-plane gratings before being detected in a focal plane camera comprised of four Electron Mu...

  1. Auditory spatial resolution in horizontal, vertical, and diagonal planes

    Science.gov (United States)

    Grantham, D. Wesley; Hornsby, Benjamin W. Y.; Erpenbeck, Eric A.

    2003-08-01

    Minimum audible angle (MAA) and minimum audible movement angle (MAMA) thresholds were measured for stimuli in horizontal, vertical, and diagonal (60°) planes. A pseudovirtual technique was employed in which signals were recorded through KEMAR's ears and played back to subjects through insert earphones. Thresholds were obtained for wideband, high-pass, and low-pass noises. Only 6 of 20 subjects obtained wideband vertical-plane MAAs less than 10°, and only these 6 subjects were retained for the complete study. For all three filter conditions thresholds were lowest in the horizontal plane, slightly (but significantly) higher in the diagonal plane, and highest for the vertical plane. These results were similar in magnitude and pattern to those reported by Perrott and Saberi [J. Acoust. Soc. Am. 87, 1728-1731 (1990)] and Saberi and Perrott [J. Acoust. Soc. Am. 88, 2639-2644 (1990)], except that these investigators generally found that thresholds for diagonal planes were as good as those for the horizontal plane. The present results are consistent with the hypothesis that diagonal-plane performance is based on independent contributions from a horizontal-plane system (sensitive to interaural differences) and a vertical-plane system (sensitive to pinna-based spectral changes). Measurements of the stimuli recorded through KEMAR indicated that sources presented from diagonal planes can produce larger interaural level differences (ILDs) in certain frequency regions than would be expected based on the horizontal projection of the trajectory. Such frequency-specific ILD cues may underlie the very good performance reported in previous studies for diagonal spatial resolution. Subjects in the present study could apparently not take advantage of these cues in the diagonal-plane condition, possibly because they did not externalize the images to their appropriate positions in space or possibly because of the absence of a patterned visual field.

  2. Is the phase of plane waves an invariant?

    OpenAIRE

    Huang, Young-Sea

    2009-01-01

    Based on the invariance of the phase of waves, plane waves was shown to propagate with negative frequencies in a medium which moves at superluminal speeds opposite to the propagation direction of plane waves. The validity of the invariance of the phase of plane waves was then called into question. A radical change of the conventional concept of plane waves is recently proposed to solve the problem of negative frequency of waves. Here, we point out flaws in that proposal. Thus, the validity of...

  3. Information Model for Resource of ASON Control Plane

    Institute of Scientific and Technical Information of China (English)

    XU Yun-bin; SONG Hong-sheng; GUI Xuan; ZHANG Jie; GU Wan-yi

    2004-01-01

    Automatic Switched Optical network (ASON) is the key technology for the next generation optical networks, and the recommendations for ASON were also developed by ITU-T. However, the recommendations for the management plane have not been made yet. In this paper, the management information model for the resources of control plane is proposed based on the management requirements of ASON for the first time. The managed objects for control plane could be used for the management of control Network Elements(NEs) and control channels, they can also be used for route areas division in control plane, parameter configuration and performance inspection for the control modules in a control NEs.

  4. The plane wave spectrum representation of electromagnetic fields

    CERN Document Server

    Clemmow, P C

    1966-01-01

    The Plane Wave Spectrum Representation of Electromagnetic Fields presents the theory of the electromagnetic field with emphasis to the plane wave. This book explains how fundamental electromagnetic fields can be represented by the superstition of plane waves traveling in different directions. Organized into two parts encompassing eight chapters, this book starts with an overview of the methods whereby plane wave spectrum representation can be used in attacking different characteristic problems belonging to the theories of radiation, diffraction, and propagation. This book then discusses the co

  5. VARIABLE RADIO SOURCES IN THE GALACTIC PLANE

    International Nuclear Information System (INIS)

    Using three epochs of Very Large Array observations of the Galactic plane in the first quadrant taken ∼15 years apart, we have conducted a search for a population of variable Galactic radio emitters in the flux density range 1-100 mJy at 6 cm. We find 39 variable sources in a total survey area of 23.2 deg2. Correcting for various selection effects and for the extragalactic variable population of active galactic nuclei, we conclude there are ∼1.6 deg-2 Galactic sources which vary by more than 50% on a time scale of years (or shorter). We show that these sources are much more highly variable than extragalactic objects; more than 50% show variability by a factor >2 compared to <10% for extragalactic objects in the same flux density range. We also show that the fraction of variable sources increases toward the Galactic center (another indication that this is a Galactic population), and that the spectral indices of many of these sources are flat or inverted. A small number of the variables are coincident with mid-IR sources and two are coincident with X-ray emitters, but most have no known counterparts at other wavelengths. Intriguingly, one lies at the center of a supernova remnant, while another appears to be a very compact planetary nebula; several are likely to represent activity associated with star formation regions. We discuss the possible source classes which could contribute to the variable cohort and follow-up observations which could clarify the nature of these sources.

  6. The Galactic Plane Infrared Polarization Survey (GPIPS)

    Science.gov (United States)

    Clemens, Dan P.; Pinnick, A. F.; Pavel, M. D.; Taylor, B. W.

    2012-06-01

    The scientific motivation, data collection strategy, data reduction, and analysis methods are presented for the Galactic Plane Infrared Polarization Survey (GPIPS). The chief goal for the Survey was to reveal the nature of the magnetic field threading the Galactic disk, in particular through regions of low to moderate extinction (1-20 mag of AV ) and star formation in the cool interstellar medium. The Survey region spans 76 deg2 of the northern Milky Way disk, from l = 18° to 56° and b =-1° to +1°. Linear polarimetric imaging observations began in 2006 in the near-infrared H band (1.6 μm) using the Mimir instrument on the 1.8 m Perkins telescope, located outside Flagstaff, AZ. Mimir used a cold, fixed wire grid and a rotateable cold, compound half-wave plate to obtain "step-and-integrate" polarimetry over its full 10 × 10 arcmin field of view. The GPIPS bright and faint polarimetric limits are approximately 7th and 15th mag, respectively, set by saturation and photon noise. Polarimetric uncertainties track with stellar magnitude, from about 0.1% to 25%, on average, from the brightest to faintest stars. Across the 3237 field GPIPS region, approximately 0.5 million stars are estimated to show detectable linear polarization (P/σ P > 3); most of these have mH < 12. This represents many orders of magnitude improvement in the number of polarization measurements across this region. GPIPS observations are more than 90% complete and should finish in 2012.

  7. Three different approaches to Transversus abdominis plane

    Directory of Open Access Journals (Sweden)

    Zoka Milan

    2011-08-01

    Full Text Available Aim The transversus abdominis plane (TAP block is a new techniquefor providing analgesia to the anterior abdominal wall. There is ongoing debate regarding access point for TAP block. The aim of this cadaveric study was to compare the spread of 40 mL of dye using three different approaches to TAP: subcostal , via the mid-axillary and via the lumbar triangle of Petit (LTOP. Methods Injection of black dye into the TAP was performed for each hemi-abdominal wall of 13 embalmed human cadavers by using 3 different access points: subcostal (9 hemi-abdomens, mid-axillary (9 and LTOP (8. This was followed by dissection to determine the extent of dye spread and nerve involvement in the dye injection. The shapes of the dye were traced onto clear plastic, which was then photographed. These digital photographs were loaded into the mathematical software programme Matlab, and the outline of the dye spread was digitised using a piecewise cubic spline, enabling the shapes to be plotted on a graph and the areas to be calculated. Results The area of the dye spread for subcostal, mid-axillary and LTOP was 85.1 (T7-L1, 58.9 (T10-L1 and 77.9cm2 (T10-L1, respectively. There was statistically significant difference between area of dye spread between subcostal and mid-axillary approach (p<0.01. Conclusion This dye injection study in a cadaver model indicates that subcostal approach is associated with a larger area of spread of dye than the mid-axillary approach. Dye injected through subcostal, mid-axillary and LTOP approaches demonstrated different nerve involvement.

  8. Mass accumulation rates and fallout radionuclides 210Pb, 137Cs and 241Am inventories determined in radiometrically dated abyssal sediments of the Black Sea

    International Nuclear Information System (INIS)

    Five abyssal (deep-sea) sediment cores collected during the two international cruises on R/V 'Professor Vodyanitskiy' (RADEUX-1998 and RADEUX-2000) in the framework of the Regional Technical Co-operation Project RER/2/003 'Marine Environmental Assessment in the Black Sea Region' were subjected to detailed radiometric analysis. The sediments were dated using the radionuclides 210Pb, 137Cs and 241Am and the results used to calculate a number of key parameters, e.g. radionuclide inventories, fluxes and sediment accumulation rates. The sediment cores were collected using a MARK II-400 multi-corer (Bowers and Connelly) in both Western and Eastern sub-basins of the Black Sea. The cores were sliced on board with a resolution of 0.2-0.4 cm for the top 5 cm and 1-5 cm downward using an extruder that was specially designed to prevent loss of the uppermost fluff-layer, possible down-smearing and interlayer cross-contamination of the sediment. Dry bulk density (DBD) and cumulative dry mass (CDM) were calculated on a salt-free basis using direct determination of the salt contribution to the dry mass of the sediment. Calculations showed that in the near surface sediments, and particularly in the top fluff-layer, the salt dissolved in pore-water contributed up to 30-60% of the mass of dried sediments. Neglecting this correction could cause an erroneous interpretation of the 210Pb activity profile, resulting in overestimation of both the average sedimentation rate and its recent temporal changes. Sediment samples were analysed for 210Pb, 226Ra, 137Cs and 241Am by direct gamma assay in UHMI after 3 weeks equilibration in hermetically sealed plastic holders, using an EG and G Ortec (Ametek) HPGe GWL series well-type coaxial low background intrinsic germanium detector. Correction was made for the effect of self-absorption of low energy γ-rays within the sample using attenuation parameters determined in. Chronostratigraphical analysis of the data and sediment age calculation have

  9. Compact Focal Plane Assembly for Planetary Science

    Science.gov (United States)

    Brown, Ari; Aslam, Shahid; Huang, Wei-Chung; Steptoe-Jackson, Rosalind

    2013-01-01

    A compact radiometric focal plane assembly (FPA) has been designed in which the filters are individually co-registered over compact thermopile pixels. This allows for construction of an ultralightweight and compact radiometric instrument. The FPA also incorporates micromachined baffles in order to mitigate crosstalk and low-pass filter windows in order to eliminate high-frequency radiation. Compact metal mesh bandpass filters were fabricated for the far infrared (FIR) spectral range (17 to 100 microns), a game-changing technology for future planetary FIR instruments. This fabrication approach allows the dimensions of individual metal mesh filters to be tailored with better than 10- micron precision. In contrast, conventional compact filters employed in recent missions and in near-term instruments consist of large filter sheets manually cut into much smaller pieces, which is a much less precise and much more labor-intensive, expensive, and difficult process. Filter performance was validated by integrating them with thermopile arrays. Demonstration of the FPA will require the integration of two technologies. The first technology is compact, lightweight, robust against cryogenic thermal cycling, and radiation-hard micromachined bandpass filters. They consist of a copper mesh supported on a deep reactive ion-etched silicon frame. This design architecture is advantageous when constructing a lightweight and compact instrument because (1) the frame acts like a jig and facilitates filter integration with the FPA, (2) the frame can be designed so as to maximize the FPA field of view, (3) the frame can be simultaneously used as a baffle for mitigating crosstalk, and (4) micron-scale alignment features can be patterned so as to permit high-precision filter stacking and, consequently, increase the filter bandwidth and sharpen the out-of-band rolloff. The second technology consists of leveraging, from another project, compact and lightweight Bi0.87Sb0.13/Sb arrayed thermopiles

  10. Selection of planes in nuclear magnetic resonance tomography

    International Nuclear Information System (INIS)

    A prototype aiming to obtain images in nuclear magnetic resonance tomography was developed, by adjusting NMR spectrometer in the IFQSC Laboratory. The techniques for selecting planes were analysed by a set of computer codes, which were elaborated from Bloch equation solutions to simulate the spin system behaviour. Images were obtained using planes with thickness inferior to 1 cm. (M.C.K.)

  11. With US$5 Billion,China Purchases 42 Boeing Planes

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ On August 8, Air China, China Eastern Airlines, Shanghai Airlines, Xiamen Airlines signed the final Purchase agreement of 42 Boeing planes with Boeing. The price in catalogue is US$5.04 billion. The first plane will be delivered in 2008.

  12. ON A PERIMETER-PRESERVING PLANE CURVE FLOW

    Institute of Scientific and Technical Information of China (English)

    PanShengliang

    2001-01-01

    The purpose of this paper is to investigate a new type of evolution problem for closedconvex plane curves which will preserves the perimeter of the curve but expands the enclosedarea and the final limiting curve is a circle in the Hausdorff metric in the plane.

  13. Plane Transformations in a Complex Setting III: Similarities

    Science.gov (United States)

    Dana-Picard, Thierry

    2009-01-01

    This is the third part of a study of plane transformations described in a complex setting. After the study of homotheties, translations, rotations and reflections, we proceed now to the study of plane similarities, either direct or inverse. Their group theoretical properties are described, and their action on classical geometrical objects is…

  14. Integral representation in the hodograph plane for compressible flow problems

    DEFF Research Database (Denmark)

    Hansen, Erik Bent; Hsiao, George C.

    1999-01-01

    The compressible flow equations are linear in the hodograph plane. This fact is exploited to derive a representation formula and to construct a fundamental solution for compressible, subsonic flow problems.......The compressible flow equations are linear in the hodograph plane. This fact is exploited to derive a representation formula and to construct a fundamental solution for compressible, subsonic flow problems....

  15. With US$5 Billion,China Purchases 42 Boeing Planes

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

      On August 8, Air China, China Eastern Airlines, Shanghai Airlines, Xiamen Airlines signed the final Purchase agreement of 42 Boeing planes with Boeing. The price in catalogue is US$5.04 billion. The first plane will be delivered in 2008.……

  16. Random skew plane partitions with a piecewise periodic back wall

    DEFF Research Database (Denmark)

    Boutillier, Cedric; Mkrtchyan, Sevak; Reshetikhin, Nicolai;

    Random skew plane partitions of large size distributed according to an appropriately scaled Schur process develop limit shapes. In the present work we consider the limit of large random skew plane partitions where the inner boundary approaches a piecewise linear curve with non-lattice slopes. Much...

  17. THE PROJECTIVE PLANE CROSSING NUMBERS OF CIRCULAR GRAPHS

    Institute of Scientific and Technical Information of China (English)

    Dengju MA; Han REN

    2008-01-01

    The authors give an upper bound for the projective plane crossing number of a circular graph. Also, the authors prove the projective plane crossing numbers of circular graph C (8,3) and C (9,3) are 2 and 1, respectively.

  18. Plane-wave least-squares reverse-time migration

    KAUST Repository

    Dai, Wei

    2013-06-03

    A plane-wave least-squares reverse-time migration (LSRTM) is formulated with a new parameterization, where the migration image of each shot gather is updated separately and an ensemble of prestack images is produced along with common image gathers. The merits of plane-wave prestack LSRTM are the following: (1) plane-wave prestack LSRTM can sometimes offer stable convergence even when the migration velocity has bulk errors of up to 5%; (2) to significantly reduce computation cost, linear phase-shift encoding is applied to hundreds of shot gathers to produce dozens of plane waves. Unlike phase-shift encoding with random time shifts applied to each shot gather, plane-wave encoding can be effectively applied to data with a marine streamer geometry. (3) Plane-wave prestack LSRTM can provide higher-quality images than standard reverse-time migration. Numerical tests on the Marmousi2 model and a marine field data set are performed to illustrate the benefits of plane-wave LSRTM. Empirical results show that LSRTM in the plane-wave domain, compared to standard reversetime migration, produces images efficiently with fewer artifacts and better spatial resolution. Moreover, the prestack image ensemble accommodates more unknowns to makes it more robust than conventional least-squares migration in the presence of migration velocity errors. © 2013 Society of Exploration Geophysicists.

  19. Function algebras on a 2-dimensional quantum complex plane

    International Nuclear Information System (INIS)

    The well-behaved representations of the coordinate algebra of a 2-dimensional quantum complex plane are classified and a C*-algebra is defined which can be viewed as the algebra of continuous functions on the 2-dimensional quantum complex plane vanishing at infinity

  20. Non-linear flow response and reaction plane correlations

    OpenAIRE

    Teaney, Derek; Yan, Li

    2012-01-01

    We apply the non-linear flow response formalism to the recently measured event plane correlations. We find that as a result of the combined effects of linear and non-linear flow response, the observed event plane correlations can be understood as an effective average of the 'linear limit' and 'non-linear limit'.

  1. Electric field modelling for point-plane gap

    International Nuclear Information System (INIS)

    The electric field distribution for point-plane gap is modelled both for stressed point and stressed plane electrodes. In simulations, the influence of the discharge chamber walls is taken into account. The size of an avalanche and the corresponding current pulse are calculated. The results are compared with those got other field distribution approximations. (author)

  2. Gain induced stability of active plane-parallel resonators

    NARCIS (Netherlands)

    Witteman, W.J.; Ernst, G.J.

    1975-01-01

    It has been observed for a plane-parallel resonator with a saturated medium that under certain conditions confined beams mainly concentrated near the axis are present. The experiments have been done with a sealed-off plane-parallel CO2 laser of one meter length and with an internal diameter of 20 mm

  3. Surface anatomy and anatomical planes in the adult turkish population.

    Science.gov (United States)

    Uzun, C; Atman, E D; Ustuner, E; Mirjalili, S A; Oztuna, D; Esmer, T S

    2016-03-01

    Surface anatomy and anatomical planes are widely used in education and clinical practice. The planes are largely derived from cadaveric studies and their projections on the skin show discrepancies between and within anatomical reference textbooks. In this study, we reassessed the accuracy of common thoracic and abdominopelvic anatomical planes using computed tomography (CT) imaging in the live adult Turkish population. After patients with distorting pathologies had been excluded, CT images of 150 supine patients at the end tidal inspiration were analyzed. Sternal angle, transpyloric, subcostal, supracristal and pubic crest planes and their relationships to anatomical structures were established by dual consensus. The tracheal bifurcation, azygos vein/superior vena cava (SVC) junction and pulmonary bifurcation were usually below the sternal angle while the concavity of the aortic arch was generally within the plane. The tip of the tenth rib, the superior mesenteric artery and the portal vein were usually within the transpyloric plane while the renal hila and the fundus of the gallbladder were below it. The inferior mesenteric artery was below the subcostal plane and the aortic bifurcation was below the supracristal plane in most adults. Projectional surface anatomy is fundamental to medical education and clinical practice. Modern cross-sectional imaging techniques allow large groups of live patients to be examined. Classic textbook information regarding anatomy needs to be reviewed and updated using the data gathered from these recent studies, taking ethnic differences into consideration. Clin. Anat. 29:183-190, 2016. © 2015 Wiley Periodicals, Inc. PMID:26403267

  4. On rationality of logarithmic Q-homology planes - I

    International Nuclear Information System (INIS)

    Normal surfaces over the complex plane are considered that are logarithmic (i.e., all its singularities are of the quotient type) and of which all reduced homology groups with rational coefficients vanish. It is proved that all such planes are rational. 16 refs

  5. Precession of a Spinning Ball Rolling down an Inclined Plane

    Science.gov (United States)

    Cross, Rod

    2015-01-01

    A routine problem in an introductory physics course considers a rectangular block at rest on a plane inclined at angle a to the horizontal. In order for the block not to slide down the incline, the coefficient of sliding friction, µ, must be at least tan a. The situation is similar for the case of a ball rolling down an inclined plane. In order…

  6. Uniform theory for the diffraction of evanescent plane waves.

    Science.gov (United States)

    Umul, Yusuf Z

    2007-08-01

    A uniform diffracted field is obtained in terms of Fresnel functions with complex argument by subtracting the unit step function from the Fresnel integral. The method is applied to the problem of diffraction of inhomogeneous plane waves by a perfectly conducting half-plane and wedge. The results are plotted numerically and compared with results reported in the literature. PMID:17621346

  7. Free motion on the Poisson plane and sphere

    OpenAIRE

    Zakrzewski, S.

    1996-01-01

    Poisson plane and sphere --- homogeneous spaces of Poisson groups E(2) and SU(2) (resp.) --- have phase spaces (corresponding symplectic groupoids), in which a free Hamiltonian is naturally defined. We solve the equations of motion and point out some unexpected features: free motion on the plane is bounded (periodic) and free trajectories on the sphere are all circles except the big ones.

  8. Z$_3$-graded differential geometry of quantum plane

    OpenAIRE

    Celik, Salih

    2002-01-01

    In this work, the Z$_3$-graded differential geometry of the quantum plane is constructed. The corresponding quantum Lie algebra and its Hopf algebra structure are obtained. The dual algebra, i.e. universal enveloping algebra of the quantum plane is explicitly constructed and an isomorphism between the quantum Lie algebra and the dual algebra is given.

  9. Plane Stratified Flow in a Room Ventilated by Displacement Ventilation

    DEFF Research Database (Denmark)

    Nielsen, Peter Vilhelm; Nickel, J.; Baron, D. J. G.

    2004-01-01

    The air movement in the occupied zone of a room ventilated by displacement ventilation exists as a stratified flow along the floor. This flow can be radial or plane according to the number of wall-mounted diffusers and the room geometry. The paper addresses the situations where plane flow is obta...... flow. The thickness and the velocity are functions of the Archimedes number....

  10. Power tracks instead of planes to reduce radiated electromagnetic fields

    NARCIS (Netherlands)

    Leferink, Frank B.J.; Etten, van Wim C.

    2006-01-01

    The noise voltage in the reference or ground of a printed circuit board is often the cause of unwanted radiated emission. Power supply planes attribute to the noise voltage. By replacing the power supply planes by tracks, the noise voltage in the reference or ground can be reduced, which leads to a

  11. Analysis of nulling phase functions suitable to image plane coronagraphy

    CERN Document Server

    Henault, Francois; Verinaud, Christophe

    2016-01-01

    Coronagraphy is a very efficient technique for identifying and characterizing extra-solar planets orbiting in the habitable zone of their parent star, especially when used in a space environment. An important family of coronagraphs is based on phase plates located at an intermediate image plane of the optical system, that spread the starlight outside the "Lyot" exit pupil plane of the instrument. In this communication we present a set of candidate phase functions generating a central null at the Lyot plane, and study how it propagates to the image plane of the coronagraph. These functions include linear azimuthal phase ramps (the well-known optical vortex), azimuthally cosine-modulated phase profiles, and circular phase gratings. Numerical simulations of the expected null depth, inner working angle, sensitivity to pointing errors, effect of central obscuration located at the pupil or image planes, and effective throughput including image mask and Lyot stop transmissions are presented and discussed. The prelim...

  12. Development of Ray Tracing Algorithms for Scanning Plane and Transverse Plane Analysis for Satellite Multibeam Application

    Directory of Open Access Journals (Sweden)

    N. H. Abd Rahman

    2014-01-01

    Full Text Available Reflector antennas have been widely used in many areas. In the implementation of parabolic reflector antenna for broadcasting satellite applications, it is essential for the spacecraft antenna to provide precise contoured beam to effectively serve the required region. For this purpose, combinations of more than one beam are required. Therefore, a tool utilizing ray tracing method is developed to calculate precise off-axis beams for multibeam antenna system. In the multibeam system, each beam will be fed from different feed positions to allow the main beam to be radiated at the exact direction on the coverage area. Thus, detailed study on caustics of a parabolic reflector antenna is performed and presented in this paper, which is to investigate the behaviour of the rays and its relation to various antenna parameters. In order to produce accurate data for the analysis, the caustic behaviours are investigated in two distinctive modes: scanning plane and transverse plane. This paper presents the detailed discussions on the derivation of the ray tracing algorithms, the establishment of the equations of caustic loci, and the verification of the method through calculation of radiation pattern.

  13. Vergence and accommodation to multiple-image-plane stereoscopic displays: 'Real world' responses with practical image-plane separations?

    Science.gov (United States)

    MacKenzie, K. J.; Dickson, R. A.; Watt, S. J.

    2011-03-01

    Conventional stereoscopic displays present images on a single focal plane. The resulting mismatch between the stimuli to the eyes' focusing response (accommodation) and to convergence causes fatigue and poor stereo performance. One promising solution is to distribute image intensity across a number of relatively widely spaced image planes - a technique referred to as depth filtering. Previously, we found this elicits accurate, continuous monocular accommodation responses with image-plane separations as large as 1.1 Diopters, suggesting that a relatively small (i.e. practical) number of image planes is sufficient to eliminate vergence-accommodation conflicts over a large range of simulated distances. However, accommodation responses have been found to overshoot systematically when the same stimuli are viewed binocularly. Here, we examined the minimum image-plane spacing required for accurate accommodation to binocular depth-filtered images. We compared accommodation and vergence responses to step changes in depth for depth-filtered stimuli, using image-plane separations of 0.6-1.2 D, and equivalent real stimuli. Accommodation responses to real and depth-filtered stimuli were equivalent for image-plane separations of ~0.6-0.9 D, but inaccurate thereafter. We conclude that depth filtering can be used to precisely match accommodation and vergence demand in a practical stereoscopic display, using a relatively small number of image planes.

  14. Diffraction of a plane wave on a half-plane located at the vacuum-anti-vacuum interface

    Science.gov (United States)

    Fisanov, V. V.

    2011-06-01

    The Wiener-Hopf method (the Jones variant) is used to solve the problem of diffraction of a plane electromagnetic wave incident normally on the perfectly conducting half-plane located at the vacuum-anti-vacuum interface. Exact analytical solutions comprising the Fresnel integrals are derived for vertical and horizontal polarization states.

  15. Planes of satellite galaxies and the cosmic web

    Science.gov (United States)

    Libeskind, Noam I.; Hoffman, Yehuda; Tully, R. Brent; Courtois, Helene M.; Pomarède, Daniel; Gottlöber, Stefan; Steinmetz, Matthias

    2015-09-01

    Recent observational studies have demonstrated that the majority of satellite galaxies tend to orbit their hosts on highly flattened, vast, possibly corotating planes. Two nearly parallel planes of satellites have been confirmed around the M31 galaxy and around the Centaurus A galaxy, while the Milky Way also sports a plane of satellites. It has been argued that such an alignment of satellites on vast planes is unexpected in the standard Λ cold dark matter (ΛCDM) model of cosmology if not even in contradiction to its generic predictions. Guided by ΛCDM numerical simulations, which suggest that satellites are channelled towards hosts along the axis of the slowest collapse as dictated by the ambient velocity shear tensor, we re-examine the planes of local satellites systems within the framework of the local shear tensor derived from the Cosmicflows-2 data set. The analysis reveals that the Local Group and Centaurus A reside in a filament stretched by the Virgo cluster and compressed by the expansion of the Local Void. Four out of five thin planes of satellite galaxies are indeed closely aligned with the axis of compression induced by the Local Void. Being the less massive system, the moderate misalignment of the Milky Way's satellite plane can likely be ascribed to its greater susceptibility to tidal torques, as suggested by numerical simulations. The alignment of satellite systems in the local Universe with the ambient shear field is thus in general agreement with predictions of the ΛCDM model.

  16. Vectorial and plane energy fluences - useful concepts in radiation physics

    International Nuclear Information System (INIS)

    The vectorial physical quantities describing the radiation field are defined in this report. The use of these quantities is rare in the radiation dosimetry literature since a knowledge of the directions of motion of the ionizing particle is often uninteresting when determining absorbed doses. However the plane energy fluence rate is a useful quantity in cases with plane irradiation geometries. The plane energy fluence rate is closely related to the vectorial energy fluence rate. The backscattering properties of a medium can be expressed in terms either of its albedo or its reflection-coefficient (backscatter-coefficient). These quantities are discussed in order to derive useful relations between the plane energy fluence and the energy fluence at points on an extended plane surface. Examples are also given of erroneous use of energy fluence instead of vectorial or plane energy fluence. The examples are taken from roentgen diagnostic examinations. To prevent further mistakes it could be valuable if the quantities of vectorial and plane fluences were introduced in text books in radiation dosimetry. Awaiting for this, this report may hopefully be useful. (E.R.)

  17. Limits of PGL(3)-translates of plane curves, II

    OpenAIRE

    Aluffi, Paolo

    2007-01-01

    Every complex plane curve C determines a subscheme S of the $P^8$ of 3x3 matrices, whose projective normal cone (PNC) captures subtle invariants of C. In "Limits of PGL(3)-translates of plane curves, I" we obtain a set-theoretic description of the PNC and thereby we determine all possible limits of families of plane curves whose general element is isomorphic to C. The main result of this article is the determination of the PNC as a cycle; this is an essential ingredient in our computation in ...

  18. Dark energy models in the w-w' plane

    International Nuclear Information System (INIS)

    We examine the behavior of dark energy models in the plane defined by w (the equation of state parameter for the dark energy) and w' (the derivative of w with respect to the logarithm of the scale factor). For nonphantom barotropic fluids with positive squared sound speed, we find that w'' plane. We also derive two new bounds for quintessence models in the w-w' plane: the first is a general bound for any scalar field with a monotonic potential, while the second improves on the Caldwell-Linder bound for tracker quintessence models. Observationally distinguishing barotropic models from quintessence models requires σ(w') < or approx. 1+w

  19. Analysis of a Fivefold Symmetric Superposition of Plane Waves

    CERN Document Server

    Schwarz, Michael H

    2012-01-01

    We show that a symmetric superposition of five standing plane waves can be expressed as an infinite series of terms of decreasing wavenumber, where each term is a product of five plane waves. We show that this series converges pointwise in R^2 and uniformly in any disk domain in R^2. Using this series, we provide a heuristic argument for why the locations of the local extrema of a symmetric superposition of five standing plane waves can be approximated by the vertices of a Penrose tiling.

  20. Two Planes of Satellites in the Centaurus A Group

    CERN Document Server

    Tully, R Brent; Karachentsev, Igor D; Karachentseva, Valentina E; Rizzi, Luca; Shaya, Edward J

    2015-01-01

    Tip of the red giant branch measurements based on Hubble Space Telescope and ground-based imaging have resulted in accurate distances to 29 galaxies in the nearby Centaurus A Group. All but two of the 29 galaxies lie in either of two thin planes roughly parallel with the supergalactic equator. The planes are only slightly tilted from the line-of-sight, leaving little ambiguity regarding the morphology of the structure. The planes have characteristic r.m.s. long axis dimensions of ~300 kpc and short axis dimensions of ~60 kpc, hence axial ratios ~0.2, and are separated in the short axis direction by 303 kpc.

  1. Two Planes of Satellites in the Centaurus A Group

    Science.gov (United States)

    Tully, R. Brent; Libeskind, Noam I.; Karachentsev, Igor D.; Karachentseva, Valentina E.; Rizzi, Luca; Shaya, Edward J.

    2015-04-01

    Tip of the red giant branch measurements based on Hubble Space Telescope and ground-based imaging have resulted in accurate distances to 29 galaxies in the nearby Centaurus A Group. All but 2 of the 29 galaxies lie in either of two thin planes roughly parallel with the supergalactic equator. The planes are only slightly tilted from the line of sight, leaving little ambiguity regarding the morphology of the structure. The planes have characteristic rms long axis dimensions of ∼300 kpc and short axis dimensions of ∼60 kpc, hence axial ratios ∼0.2, and are separated in the short axis direction by 303 kpc.

  2. An Image Encryption Method Based on Bit Plane Hiding Technology

    Institute of Scientific and Technical Information of China (English)

    LIU Bin; LI Zhitang; TU Hao

    2006-01-01

    A novel image hiding method based on the correlation analysis of bit plane is described in this paper. Firstly, based on the correlation analysis, different bit plane of a secret image is hided in different bit plane of several different open images. And then a new hiding image is acquired by a nesting "Exclusive-OR" operation on those images obtained from the first step. At last, by employing image fusion technique, the final hiding result is achieved. The experimental result shows that the method proposed in this paper is effective.

  3. DLCQ and Plane Wave Matrix Big Bang Models

    OpenAIRE

    Blau, Matthias; O'Loughlin, Martin

    2008-01-01

    We study the generalisations of the Craps-Sethi-Verlinde matrix big bang model to curved, in particular plane wave, space-times, beginning with a careful discussion of the DLCQ procedure. Singular homogeneous plane waves are ideal toy-models of realistic space-time singularities since they have been shown to arise universally as their Penrose limits, and we emphasise the role played by the symmetries of these plane waves in implementing the flat space Seiberg-Sen DLCQ prescription for these c...

  4. Vacuum Plane Waves; Cartan Invariants and physical interpretation

    CERN Document Server

    Coley, Alan; Milson, Robert

    2012-01-01

    As an application of the Cartan invariants obtained using the Karlhede algorithm, we study a simple subclass of the PP-wave spacetimes, the gravitational plane waves. We provide an invariant classification of these spacetimes and then study a few notable subcases: the linearly polarized plane waves, the weak-field circularly polarized waves, and another class of plane waves found by imposing conditions on the set of invariants. As we study these spacetimes we relate the invariant structure (i.e., Cartan scalars) to the physical description of these spacetimes using the geodesic deviation equations relative to timelike geodesic observers.

  5. Goldstone’s Theorem on a Light-Like Plane

    International Nuclear Information System (INIS)

    I review various aspects of chiral symmetry and its spontaneous breaking on null planes, including the interesting manner in which Goldstone’s theorem is realized and the constraints that chiral symmetry imposes on the null-plane Hamiltonians. Specializing to QCD with N massless flavors, I show that there is an interesting limit in which the chiral constraints on the null-plane Hamiltonians can be solved to give the spin-flavor algebra SU(2N), recovering a result originally found by Weinberg using different methods. (author)

  6. Static relativistic perfect fluids with spherical, plane, or hyperbolic symmetry

    International Nuclear Information System (INIS)

    This article examines the Einstein field of equations of general relativity, when the source of the gravitational field is a perfect fluid, and the geometry is static and possesses spherical, plane, or hyperbolic symmetry. This examination unifies, extends, and amends some earlier works. It is shown that a previous qualitative treatment of static spherically symmetric perfect fluids that obey a γ-law equation of state can be extended to include the cases of plane and hyperbolic symmetry. In the case of plane symmetry, the exact solution is provided for general values of γ. This indicates defects in an earlier prescription that was given for a general equation of state

  7. Goldstone's Theorem on a Light-Like Plane

    Science.gov (United States)

    Beane, Silas R.

    2015-09-01

    I review various aspects of chiral symmetry and its spontaneous breaking on null planes, including the interesting manner in which Goldstone's theorem is realized and the constraints that chiral symmetry imposes on the null-plane Hamiltonians. Specializing to QCD with N massless flavors, I show that there is an interesting limit in which the chiral constraints on the null-plane Hamiltonians can be solved to give the spin-flavor algebra SU(2 N), recovering a result originally found by Weinberg using different methods.

  8. Vacuum plane waves: Cartan invariants and physical interpretation

    Science.gov (United States)

    Coley, A.; McNutt, D.; Milson, R.

    2012-12-01

    As an application of the Cartan invariants obtained using the Karlhede algorithm, we study a simple subclass of the PP-wave spacetimes, the gravitational plane waves. We provide an invariant classification of these spacetimes and then study a few notable subcases: the linearly polarized plane waves, the weak-field circularly polarized waves, and another class of plane waves found by imposing conditions on the set of invariants. As we study these spacetimes we relate the invariant structure (i.e., Cartan scalars) to the physical description of these spacetimes using the geodesic deviation equations relative to timelike geodesic observers.

  9. Vacuum plane waves: Cartan invariants and physical interpretation

    International Nuclear Information System (INIS)

    As an application of the Cartan invariants obtained using the Karlhede algorithm, we study a simple subclass of the PP-wave spacetimes, the gravitational plane waves. We provide an invariant classification of these spacetimes and then study a few notable subcases: the linearly polarized plane waves, the weak-field circularly polarized waves, and another class of plane waves found by imposing conditions on the set of invariants. As we study these spacetimes we relate the invariant structure (i.e., Cartan scalars) to the physical description of these spacetimes using the geodesic deviation equations relative to timelike geodesic observers. (paper)

  10. Vergence and accommodation to multiple-image-plane stereoscopic displays: ``real world'' responses with practical image-plane separations?

    Science.gov (United States)

    MacKenzie, Kevin J.; Dickson, Ruth A.; Watt, Simon J.

    2012-01-01

    Conventional stereoscopic displays present images on a single focal plane. The resulting mismatch between the stimuli to the eyes' focusing response (accommodation) and to convergence causes fatigue and poor stereo performance. One solution is to distribute image intensity across a number of widely spaced image planes--a technique referred to as depth filtering. Previously, we found this elicits accurate, continuous monocular accommodation responses with image-plane separations as large as 1.1 Diopters (D, the reciprocal of distance in meters), suggesting that a small number of image planes could eliminate vergence-accommodation conflicts over a large range of simulated distances. Evidence exists, however, of systematic differences between accommodation responses to binocular and monocular stimuli when the stimulus to accommodation is degraded, or at an incorrect distance. We examined the minimum image-plane spacing required for accurate accommodation to binocular depth-filtered images. We compared accommodation and vergence responses to changes in depth specified by depth filtering, using image-plane separations of 0.6 to 1.2 D, and equivalent real stimuli. Accommodation responses to real and depth-filtered stimuli were equivalent for image-plane separations of ~0.6 to 0.9 D, but differed thereafter. We conclude that depth filtering can be used to precisely match accommodation and vergence demand in a practical stereoscopic display.

  11. An anatomical evaluation of the serratus anterior plane block.

    Science.gov (United States)

    Mayes, J; Davison, E; Panahi, P; Patten, D; Eljelani, F; Womack, J; Varma, M

    2016-09-01

    The serratus anterior plane block has been described for analgesia of the hemithorax. This study was conducted to determine the spread of injectate and investigate the anatomical basis of the block. Ultrasound-guided serratus anterior plane block was performed on six soft-fix embalmed cadavers. All cadavers received bilateral injections, on one side performed with 20 ml latex and on the other with 20 ml methylene blue. Subsequent dissection explored the extent of spread and nerve involvement. Photographs were taken throughout dissection. The intercostal nerves were involved on three occasions with dye, but not with latex. The lateral cutaneous branches of the intercostal nerve contained dye and latex on all occasions. The serratus plane block appears to be mediated through blockade of the lateral cutaneous branches of the intercostal nerves. Anatomically, serratus plane block does not appear to be equivalent to paravertebral block for rib fracture analgesia. PMID:27440171

  12. Study on the cutting plane friction law of sandstone

    Institute of Scientific and Technical Information of China (English)

    ZHAI Ying-da (翟英达); KANG Li-xun(康立勋)

    2003-01-01

    The friction characteristics of rock damage plane have important impact on the stability of block structure formed after the stratum is broken. The mechanics properties of rock damage plane are described by parameters such as roughness coefficient, wall compress strength and basic friction angle. These three coefficients for fine grain sandstone and medium-granular sandstone and grit sandstone are test. The friction stress is researched at the condition of different normal compressive stress acting on the tension damage plane. The friction law of tension damage plane of sandstone abided by is summed up. This law will provide scientific basis for block structure stability judging in basic roof stratum and roof pressure intensity calculating.

  13. Numerical simulation of plane target in airflow under laser irradiation

    International Nuclear Information System (INIS)

    A model of a plane target under laser irradiation is used to numerically simulate the temperature distribution in different speed airflow, using the thermal coupling method of gas and solid. The results show that there is a higher equilibrium temperature over the plane target when there is no laser irradiation, and the heat transfer coefficient between air and the plane target increases with the airflow speed; with a maximum value occurring at the front edge of the target, it declines along the target length. When under laser irradiation in different cases, the temperature distribution in the plane is analyzed carefully, and the influence of aerodynamic heating, forced convection cooling and laser heating is focused to compare their thermal competition, which shows that the temperature distributions in the target results from several thermal competition ultimately. (authors)

  14. Lumbar pedicle screw placement: Using only AP plane imaging

    Directory of Open Access Journals (Sweden)

    Anil Sethi

    2012-01-01

    Conclusion: Placement of pedicle screws under fluoroscopic guidance using AP plane imaging alone with tactile guidance is safe, fast, and reliable. However, a good understanding of the radiographic landmarks is a prerequisite.

  15. Regularized plane-wave least-squares Kirchhoff migration

    KAUST Repository

    Wang, Xin

    2013-09-22

    A Kirchhoff least-squares migration (LSM) is developed in the prestack plane-wave domain to increase the quality of migration images. A regularization term is included that accounts for mispositioning of reflectors due to errors in the velocity model. Both synthetic and field results show that: 1) LSM with a reflectivity model common for all the plane-wave gathers provides the best image when the migration velocity model is accurate, but it is more sensitive to the velocity errors, 2) the regularized plane-wave LSM is more robust in the presence of velocity errors, and 3) LSM achieves both computational and IO saving by plane-wave encoding compared to shot-domain LSM for the models tested.

  16. Mergers of elliptical galaxies and the fundamental plane

    NARCIS (Netherlands)

    Gonzalez-Garcia, AC; van Albada, TS; AvilaReese,; Firmani, C; Frenk, CS; Allen, YC

    2003-01-01

    N-body simulations have been carried out in order to explore the final state of elliptical galaxies after encounters and more expecifically whether the Fundamental Plane (FP hereafter) relation is affected by merging.

  17. Conformal Killing Vectors Of Plane Symmetric Four Dimensional Lorentzian Manifolds

    CERN Document Server

    Khan, Suhail; Bokhari, Ashfaque H; Khan, Gulzar Ali; Mathematics, Department of; Peshawar, University of; Pakhtoonkhwa, Peshawar Khyber; Pakistan.,; Petroleum, King Fahd University of; Minerals,; 31261, Dhahran; Arabia, Saudi

    2015-01-01

    In this paper, we investigate conformal Killing's vectors (CKVs) admitted by some plane symmetric spacetimes. Ten conformal Killing's equations and their general forms of CKVs are derived along with their conformal factor. The existence of conformal Killing's symmetry imposes restrictions on the metric functions. The conditions imposing restrictions on these metric functions are obtained as a set of integrability conditions. Considering the cases of time-like and inheriting CKVs, we obtain spacetimes admitting plane conformal symmetry. Integrability conditions are solved completely for some known non-conformally flat and conformally flat classes of plane symmetric spacetimes. A special vacuum plane symmetric spacetime is obtained, and it is shown that for such a metric CKVs are just the homothetic vectors (HVs). Among all the examples considered, there exists only one case with a six dimensional algebra of special CKVs admitting one proper CKV. In all other examples of non-conformally flat metrics, no proper ...

  18. Can plane wave modes be physical modes in soliton models?

    CERN Document Server

    Aldabe, F

    1995-01-01

    I show that plane waves may not be used as asymptotic states in soliton models because they describe unphysical states. When asymptotic states are taken to be physical there is no T-matrix of \\cO(1).

  19. DLCQ and plane wave matrix Big Bang models

    Science.gov (United States)

    Blau, Matthias; O'Loughlin, Martin

    2008-09-01

    We study the generalisations of the Craps-Sethi-Verlinde matrix big bang model to curved, in particular plane wave, space-times, beginning with a careful discussion of the DLCQ procedure. Singular homogeneous plane waves are ideal toy-models of realistic space-time singularities since they have been shown to arise universally as their Penrose limits, and we emphasise the role played by the symmetries of these plane waves in implementing the flat space Seiberg-Sen DLCQ prescription for these curved backgrounds. We then analyse various aspects of the resulting matrix string Yang-Mills theories, such as the relation between strong coupling space-time singularities and world-sheet tachyonic mass terms. In order to have concrete examples at hand, in an appendix we determine and analyse the IIA singular homogeneous plane wave - null dilaton backgrounds.

  20. DLCQ and Plane Wave Matrix Big Bang Models

    CERN Document Server

    Blau, Matthias

    2008-01-01

    We study the generalisations of the Craps-Sethi-Verlinde matrix big bang model to curved, in particular plane wave, space-times, beginning with a careful discussion of the DLCQ procedure. Singular homogeneous plane waves are ideal toy-models of realistic space-time singularities since they have been shown to arise universally as their Penrose limits, and we emphasise the role played by the symmetries of these plane waves in implementing the flat space Seiberg-Sen DLCQ prescription for these curved backgrounds. We then analyse various aspects of the resulting matrix string Yang-Mills theories, such as the relation between strong coupling space-time singularities and world-sheet tachyonic mass terms. In order to have concrete examples at hand, in an appendix we determine and analyse the IIA singular homogeneous plane wave - null dilaton backgrounds.

  1. DLCQ and plane wave matrix Big Bang models

    International Nuclear Information System (INIS)

    We study the generalisations of the Craps-Sethi-Verlinde matrix big bang model to curved, in particular plane wave, space-times, beginning with a careful discussion of the DLCQ procedure. Singular homogeneous plane waves are ideal toy-models of realistic space-time singularities since they have been shown to arise universally as their Penrose limits, and we emphasise the role played by the symmetries of these plane waves in implementing the flat space Seiberg-Sen DLCQ prescription for these curved backgrounds. We then analyse various aspects of the resulting matrix string Yang-Mills theories, such as the relation between strong coupling space-time singularities and world-sheet tachyonic mass terms. In order to have concrete examples at hand, in an appendix we determine and analyse the IIA singular homogeneous plane wave - null dilaton backgrounds.

  2. Ground Plane Estimation using a Hidden Markov Model

    OpenAIRE

    Dragon, Ralf; Gool, Luc >

    2014-01-01

    Dragon R., Van Gool L., ''Ground plane estimation using a hidden Markov model'', 27th IEEE conference on computer vision and pattern recognition - CVPR 2014, pp. 4026-4033, June 23-28, 2014, Columbus, Ohio, USA.

  3. Diffusion-limited aggregation on the hyperbolic plane

    OpenAIRE

    Eldan, Ronen

    2015-01-01

    We consider an analogous version of the diffusion-limited aggregation model defined on the hyperbolic plane. We prove that almost surely the aggregate viewed at time infinity will have a positive density.

  4. Nonlinear plane-symmetric perturbations of a spatial-plane Friedman universe filled with an ideal dust

    International Nuclear Information System (INIS)

    The general solution of Eistein's equations with the energy-momentum tensor of an ideal dust in the plane-symmetric case is used to obtain the generalization of the solutions for scalar perturbations in a spatial-plane Friedman universe. It is shown that, in order for plane accumulations of matter with a density much greater than the mean density of the matter in the Universe to exist in the Universe at the present time, perturbations of the density are necessary at the time of recombination, (δ/var epsilon///var epsilon/)/sub p/ /approximately/ 10/sup /minus/4/

  5. Recovery of betulinic acid from plane tree (Platanus acerifolia L.)

    OpenAIRE

    Pinilla, José María; López-Padilla, Alexis; de Vicente, G.; Fornari, Tiziana; Quintela, J C; Reglero, Guillermo

    2014-01-01

    Betulinic acid (3β, hydroxy-lup-20(29)-en-28-oic acid) is a bioactive triterpenic acid which was identified in various botanical sources and in considerable amounts in the bark of plane tree (Platanus acerifolia L.). In this work, the recovery of betulinic acid from plane tree bark was studied using different liquid solvent based extraction methods, namely solid-liquid extraction (SLE), ultrasound assisted extraction (UAE) and pressurized liquid extraction (PLE). Furthermore, preliminary stud...

  6. Quadrilateral isoparametric finite elements for plane elastic Cosserat bodies

    Institute of Scientific and Technical Information of China (English)

    Hongwu Zhang; Hui Wang; Guozhen Liu; Keren Wang

    2005-01-01

    4-node, 8-node and 8(4)-node quadrilateral plane isoparametric elements are used for the solution of bound ary value problems in linear isotropic Cosserat elasticity. The patch test is applied to validate the finite elements. Engineering problems of stress concentration around a circular hole in plane strain condition and mechanical behaviors of heterogeneous materials with rigid inclusions and pores are computed to test the accuracy and capability of these three types of finite elements.

  7. Vertical-plane pendulum absorbers for minimizing helicopter vibratory loads

    Science.gov (United States)

    Amer, K. B.; Neff, J. R.

    1974-01-01

    The use of pendulum dynamic absorbers mounted on the blade root and operating in the vertical plane to minimize helicopter vibratory loads was discussed. A qualitative description was given of the concept of the dynamic absorbers and some results of analytical studies showing the degree of reduction in vibratory loads attainable are presented. Operational experience of vertical plane dynamic absorbers on the OH-6A helicopter is also discussed.

  8. Planes of satellite galaxies: when exceptions are the rule

    Science.gov (United States)

    Cautun, Marius; Bose, Sownak; Frenk, Carlos S.; Guo, Qi; Han, Jiaxin; Hellwing, Wojciech A.; Sawala, Till; Wang, Wenting

    2015-10-01

    The detection of planar structures within the satellite systems of both the Milky Way (MW) and Andromeda (M31) has been reported as being in stark contradiction to the predictions of the standard cosmological model (Λ cold dark matter - ΛCDM). Given the ambiguity in defining a planar configuration, it is unclear how to interpret the low incidence of the MW and M31 planes in ΛCDM. We investigate the prevalence of satellite planes around galactic mass haloes identified in high-resolution cosmological simulations. We find that planar structures are very common, and that ˜10 per cent of ΛCDM haloes have even more prominent planes than those present in the Local Group. While ubiquitous, the planes of satellite galaxies show a large diversity in their properties. This precludes using one or two systems as small-scale probes of cosmology, since a large sample of satellite systems is needed to obtain a good measure of the object-to-object variation. This very diversity has been misinterpreted as a discrepancy between the satellite planes observed in the Local Group and ΛCDM predictions. In fact, ˜10 per cent of ΛCDM galactic haloes have planes of satellites that are as infrequent as the MW and M31 planes. The look-elsewhere effect plays an important role in assessing the detection significance of satellite planes and accounting for it leads to overestimating the significance level by a factor of 30 and 100 for the MW and M31 systems, respectively.

  9. Self-calibration of Antenna Errors Using Focal Plane Arrays

    Science.gov (United States)

    Napier, P. J.; Cornwell, T. J.

    The thery of focal-plane correlation is reviewed and applied to the problem of the self-calibration and self-correction of a radio telescope with errors in its reflecting surface. Curves are presented which allow the estimation of focal-plane array size and integration time needed for telescopes with varying amounts of error. It is suggested that the technique may have application to the problem of the construction of large telescopes in space.

  10. A Spiral Antenna Backed by a Conducting Plane Reflector

    OpenAIRE

    Nakano, Hisamatsu; Nogami, Kazuo; Arai, Satoshi; Mimaki, Hiroaki; Yamauchi, Junji

    1986-01-01

    An Archimedean planar spiral antenna is numerically analyzed in the presence of a conducting plane reflector. The analysis shows that the spiral antenna backed by the plane reflector has two distinct regions in the current distribution, which explain the radiation of a circularly polarized wave for the outer circumferenceCranging over about1.3 lambda 2.9 lambda, wherelambdais a free-space wavelength. Further consideration is given to a truncated spiral antenna whose out...

  11. Role of moving planes and moving spheres following Dupin cyclides

    KAUST Repository

    Jia, Xiaohong

    2014-03-01

    We provide explicit representations of three moving planes that form a μ-basis for a standard Dupin cyclide. We also show how to compute μ-bases for Dupin cyclides in general position and orientation from their implicit equations. In addition, we describe the role of moving planes and moving spheres in bridging between the implicit and rational parametric representations of these cyclides. © 2014 Elsevier B.V.

  12. Plane-wave scattering from half-wave dipole arrays

    DEFF Research Database (Denmark)

    Jensen, Niels E.

    1970-01-01

    A matrix equation for determination of plane-wave scattering from arrays of thin short-circuited dipoles of lengths about half a wavelength is derived. Numerical and experimental results are presented for linear, circular, and concentric circular arrays.......A matrix equation for determination of plane-wave scattering from arrays of thin short-circuited dipoles of lengths about half a wavelength is derived. Numerical and experimental results are presented for linear, circular, and concentric circular arrays....

  13. Orientation of planes shown up by ionic attack (1961)

    International Nuclear Information System (INIS)

    Certain recent experiments have shown that ions of low energy (3 to 15 kV), as different in nature as oxygen and argon, produced a selective attack on metallic surfaces and thus revealed certain planes of the crystal lattice of the sample bombarded. The aim of this work is to study the orientation of these planes as a function of the direction of the ions. (authors)

  14. An out of plane experiment with the SOS

    Science.gov (United States)

    Mack, D. J.

    1992-12-01

    As part of a series of talks devoted to out of plane physics with the SOS, we take advantage of this new capability to expand upon on an earlier, rejected proposal. The purpose of this is twofold: to give a didactic example of how to plan an out of plane measurement with the SOS, and to breath some life into a potentially exciting physics program is Hall C.

  15. On the Singularity Structure and Stability of Plane Waves

    CERN Document Server

    Marolf, D; Marolf, Donald; Zayas, Leopoldo A. Pando

    2003-01-01

    We describe various aspects of plane wave backgrounds. In particular, we make explicit a simple criterion for singularity by establishing a relation between Brinkmann metric entries and diffeomorphism-invariant curvature information. We also address the stability of plane wave backgrounds by analyzing the fluctuations of generic scalar modes. We focus our attention on cases where after fixing the light-cone gauge the resulting world sheet fields appear to have negative "mass terms". We nevertheless argue that these backgrounds may be stable.

  16. Galactic Plane H$\\alpha$ Surveys: IPHAS & VPHAS+

    CERN Document Server

    Wright, Nicholas J

    2015-01-01

    The optical Galactic Plane H$\\alpha$ surveys IPHAS and VPHAS+ are dramatically improving our understanding of Galactic stellar populations and stellar evolution by providing large samples of stars in short lived, but important, evolutionary phases, and high quality homogeneous photometry and images over the entire Galactic Plane. Here I summarise some of the contributions these surveys have already made to our understanding of a number of key areas of stellar and Galactic astronomy.

  17. Transversus abdominis plane block: a cadaveric and radiological evaluation.

    LENUS (Irish Health Repository)

    McDonnell, John G

    2011-04-11

    The abdominal wall is a significant source of pain after abdominal surgery. Anterior abdominal wall analgesia may assist in improving postoperative analgesia. We have recently described a novel approach to block the abdominal wall neural afferents via the bilateral lumbar triangles of Petit, which we have termed a transversus abdominis plane block. The clinical efficacy of the transversus abdominis plane block has recently been demonstrated in a randomized controlled clinical trial of adults undergoing abdominal surgery.

  18. Integral Representation of Harmonic Function in a Half-Plane

    Institute of Scientific and Technical Information of China (English)

    LI Hong Wei; DENG Guan Tie

    2009-01-01

    In this article, we consider the integral representation of harmonic functions. Using a property of the modified Poisson kernel in a half plane, we prove that a harmonic function u(z) in a half plane with its positive part u+(z)=max{u(z), 0} satisfying a slowly growing condition can be represented by its integral of a measure on the boundary of the half plan.

  19. Swimming and peristaltic pumping between two plane parallel walls

    International Nuclear Information System (INIS)

    Swimming at low Reynolds number in a fluid confined between two plane walls is studied for an infinite plane sheet located midway between the walls and distorted with a transverse propagating wave. It is shown that the flow pattern is closely related to that for peristaltic pumping. The hydrodynamic interaction between two flexible sheets swimming parallel in infinite space is related to the problem of peristaltic pumping in a planar channel with two wavy walls.

  20. Plane section of cone and cylinder in computer geometry

    OpenAIRE

    Obradović Ratko M.; Milojević Zoran

    2005-01-01

    In this paper a mathematical apparatus for determination of plane section of cone and cylinder was formed. By using the descriptive geometric approach the contour lines of these quadrics were determined. The fact that the tangent lines of a circle could be transformed to the tangent lines of an ellipse using affinity was employed. In that way surfaces are represented by contour lines (tangent lines of basic ellipse in oblique projection) and thus they have a realistic view. Intersecting plane...

  1. Magnetic field in the plane of a physical dipole

    Science.gov (United States)

    Binder, P.-M.; Grace, Alyssa L.; Hui, Kaleonui J.; Loving, Rebekah K.

    2016-07-01

    We study the magnetic field in the plane of a circular current-carrying loop. We both solve Biot–Savart’s equation numerically and perform measurements with high spatial resolution. The results extend our quantitative understanding of a physical magnetic dipole by providing an accurate and complete picture of the field in this plane, which complements existing analytical expressions valid at very small and large radius, near the loop axis, and for point dipoles.

  2. In-plane anisotropy of 1545 aluminum alloy sheet

    Institute of Scientific and Technical Information of China (English)

    PENG Yong-yi; YIN Zhi-min; YANG Jin; DU Yu-xuan

    2005-01-01

    The microstructures and the tensile mechanical properties in the rolling plane of 1545 aluminum alloy sheet at different orientations with respect to the rolling direction were studied by means of tensile test,X-ray diffractometer(XRD),optical microscope and transmission electron microscope.The in-plane anisotropy of tensile mechanical properties was calculated and the inverse pole figures of the rolling plane,transversal section and longitudinal section were obtained by Harris method.The results show that the 1545 Al alloy sheet has remarkable in-plane anisotropy of mechanical properties and the main texture component is{110}texture.On the basis of the model that regards the sheet containing only{110}texture as a monocrystal,the relationship of in-plane anisotropy and the anisotropy of crystallography was analyzed.The study shows that it is the combined effects of the anisotropy of crystallography and microstructures that cause the in-plane anisotropy of mechanical properties,but the main cause is the crystallographic texture.

  3. Simplified ground plane invisibility cloak by multilayer dielectrics.

    Science.gov (United States)

    Xu, Xiaofei; Feng, Yijun; Yu, Zhenzhong; Jiang, Tian; Zhao, Junming

    2010-11-22

    Most implementations of the ground plane invisibility cloak are based on the isotropic design through the quasi-conformal transformation. However recent theoretical analysis predicts the unavoidable lateral shift of the scattering fields associated with these cloaks making them detectable. In this paper, we propose an alternative method to design the ground plane invisibility clock with electromagnetic beam modulation blocks through simple coordinate transformation discussed in our previous work. The ground plane cloak obtained with the rigorous transformation optics possesses moderate anisotropic distributions of material parameters, but results in no lateral shift of the scattering fields. To realize the design, a possible scheme is suggested by discretizing the ground plane cloak to several homogeneous sub-blocks. These sub-blocks can be realized with multilayer isotropic dielectrics with alignment angles that are determined by the effective medium theory. Thus the non-magnetic ground plane invisibility cloak can be constructed by several multilayered normal dielectrics aligned in different angles. The performance of the proposed cloak and its practical implementation is validated by full-wave electromagnetic simulations with both near field distributions and far field scattering patterns under different EM wave incident angles. The proposed cloak is composed of normal dielectric multilayers, thus can leads to easy experimental demonstration of non-magnetic ground plane cloak in the frequency range from microwave to optical. PMID:21164794

  4. 3D plane-wave least-squares Kirchhoff migration

    KAUST Repository

    Wang, Xin

    2014-08-05

    A three dimensional least-squares Kirchhoff migration (LSM) is developed in the prestack plane-wave domain to increase the quality of migration images and the computational efficiency. Due to the limitation of current 3D marine acquisition geometries, a cylindrical-wave encoding is adopted for the narrow azimuth streamer data. To account for the mispositioning of reflectors due to errors in the velocity model, a regularized LSM is devised so that each plane-wave or cylindrical-wave gather gives rise to an individual migration image, and a regularization term is included to encourage the similarities between the migration images of similar encoding schemes. Both synthetic and field results show that: 1) plane-wave or cylindrical-wave encoding LSM can achieve both computational and IO saving, compared to shot-domain LSM, however, plane-wave LSM is still about 5 times more expensive than plane-wave migration; 2) the regularized LSM is more robust compared to LSM with one reflectivity model common for all the plane-wave or cylindrical-wave gathers.

  5. On Using Cutting Planes in Pseudo-Boolean Optimization

    Directory of Open Access Journals (Sweden)

    Vasco M. Manquinho

    2006-03-01

    Full Text Available Cutting planes are a well-known, widely used, and very effective technique for Integer Linear Programming (ILP. However, cutting plane techniques are seldom used in Pseudo-Boolean Optimization (PBO algorithms. This paper addresses the utilization of Gomory mixed-integer and clique cuts, in Satisfiability-based algorithms for PBO, and shows how these cuts can be used for computing lower bounds and for learning new constraints. A side result of learning new constraints is that the utilization of cutting planes enables non-chronological backtracking. Besides cutting planes, the paper also shows that the utilization of search restarts in PBO can be effective in practice, allowing the computation of tighter lower bounds each time the search restarts. The more aggressive lower bounds result from the constraints learned due to the utilization of cutting planes. Experimental results show that the integration of cutting planes and search restarts in a SAT-based algorithm for PBO yields a competitive new solution for PBO.

  6. Lattice Zariski k-ples of plane sextic curves and Z-splitting curves for double plane sextics

    OpenAIRE

    Shimada, Ichiro

    2010-01-01

    A simple sextic is a reduced complex projective plane curve of degree 6 with only simple singularities. We introduce a notion of Z-splitting curves for the double covering of the projective plane branching along a simple sextic, and investigate lattice Zariski k-ples of simple sextics by Z-splitting curves. We define specialization of lattice types, and classify all lattice types of Z-splitting curves of degree less than or equal to 3 up to specializations.

  7. Measurements of planing forces and cavity shapes on cylindrical afterbodies

    Science.gov (United States)

    Hellum, Aren; Belden, Jesse; Beal, David; Huyer, Stephen; Henoch, Charles; Hrubes, Dana

    2015-11-01

    Supercavitation is a drag reduction technique by which an underwater body is enclosed over a significant portion of its length in a bubble of gas. Hydrodynamic forces act on the body only through contact with the nose and a planing section at the rear. Models of the planing forces typically assume that the body is placed into a cavity which is unchanged by the presence of the body, and the present study was designed to test the validity of this assumption. Measurements were taken of the planing forces for five afterbody lengths over a range of angles concurrently with photographs showing the size and shape of the cavity produced. These observations reveal that the cavity form and growth rate are significantly affected by both the length and angle of attack of the body; the length of the cavity shrinks at the same angle of attack as the body length is reduced past a critical threshold, suggesting a hydrodynamic interaction between the afterbody trailing edge and the cavity. Additionally, the planing forces demonstrate a non-monotonic dependence on attack angle that is not readily explained by existing models, specifically a ``lift crisis'' for short bodies in which the planing lift goes to zero over a range from -1 to -3 degrees.

  8. Planes of satellite galaxies and the cosmic web

    CERN Document Server

    Libeskind, Noam I; Tully, R Brent; Courtois, Helene M; Pomarede, Daniel; Gottloeber, Stefan; Steinmetz, Matthias

    2015-01-01

    Recent observational studies have demonstrated that most satellite galaxies tend to orbit their hosts on highly flattened, vast, possibly co-rotating planes. Two nearly parallel planes of satellites have been confirmed around the M31 galaxy and around the Centaurus A galaxy, while the Milky Way also sports a plane of satellites. It has been argued that such an alignment of satellites on vast planes is unexpected in the standard ($\\Lambda$CDM) model of cosmology if not even in contradiction to its generic predictions. Guided by $\\Lambda$CDM numerical simulations, which suggest that satellites are channeled towards hosts along the axis of the slowest collapse as dictated by the ambient velocity shear tensor, we re-examine the planes of local satellites systems within the framework of the local shear tensor derived from the Cosmicflows-2 dataset. The analysis reveals that the Local Group and Centaurus A reside in a filament stretched by the Virgo cluster and compressed by the expansion of the Local Void. Four ou...

  9. Optimal aeroassisted return from high earth orbit with plane change

    Science.gov (United States)

    Vinh, Nguyen X.; Hanson, John M.

    This paper gives a complete analysis of the problem of aeroassisted return from a high Earth orbit to a low Earth orbit with plane change. A discussion of pure propulsive maneuver leads to the necessary change for improvement of the fuel consumption by inserting in the middle of the trajectory an atmospheric phase to obtain all or part of the required plane change. The variational problem is reduced to a parametric optimization problem by using the known results in optimal impulsive transfer and solving the atmospheric turning problem for storage and use in the optimization process. The coupling effect between space maneuver and atmospheric maneuver is discussed. Depending on the values of the plane change i, the ratios of the radii, n = r 1/r 2 between the orbits and a = r 2/R between the low orbit and the atmosphere, and the maximum lift-to-drag ratio E∗ of the vehicle, the optimal maneuver can be pure propulsive or aeroassisted. For aeroassisted maneuver, the optimal mode can be parabolic, which requires only drag capability of the vehicle, or elliptic. In the elliptic mode, it can be by one-impulse for deorbit and one or two-impulse in postatmospheric flight, or by two-impulse for deorbit with only one impulse for final circularization. It is shown that whenever an impulse is applied, a plane change is made. The necessary conditions for the optimal split of the plane changes are derived and mechanized in a program routine for obtaining the solution.

  10. A Statistical Framework for Utilization of Simultaneous Pupil Plane and Focal Plane Telemetry for Exoplanet Imaging, Part I: Accounting for Polarization Aberration in Multiple Planes

    CERN Document Server

    Frazin, Richard A

    2016-01-01

    A new generation of telescopes with mirror diameters of 20 m or more, called extremely large telescopes (ELTs) has the potential to provide unprecedented imaging and spectroscopy of exo-planetary systems, if the difficulties in achieving the extremely high dynamic range required to differentiate the planetary signal from the star can be overcome to a sufficient degree. Fully utilizing the potential of ELTs for exoplanet imaging will likely require simultaneous and self-consistent determination both the planetary image and the unknown aberrations in multiple planes of the optical system, using statistical inference based on the wavefront sensor and science camera data streams. This paper is the first in a series on this subject, in which a formalism is established for the exoplanet imaging problem in a polarizing optical system that has optical aberrations in multiple planes. Every effort has been made to be rigorous and complete, so that that validity of approximations to be made later can be assessed. It is ...

  11. Plane strain consolidation of soil layer with anisotropic permeability

    Institute of Scientific and Technical Information of China (English)

    Zhi-yong AI; Chao WU

    2009-01-01

    This paper presents an alternative analytical technique to study a plane strain consolidation of a poroelastic soil by taking into account the anisotropy of permeability. From the governing equations of a saturated poroelastic soil, the relationship of basic variables for a point of a soil layer is established between the ground surface (z=0) and the depth z in the Laplace-Fourier transform domain. Combined with the boundary conditions, an exact solution is derived for plane strain Biot's consolidation of a finite soil layer with anisotropic permeability in the transform domain. Numerical inversions of the Laplace transform and the Fourier transform are adopted to obtain the actual solution in the physical domain. Numerical results of plane strain Biot's consolidation for a single soil layer show that the anisotropic of permeability has a great influence on the consolidation behavior of the soils.

  12. In-plane elastic stability of fixed parabolic shallow arches

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The nonlinear behavior of fixed parabolic shallow arches subjected to a vertical uniform load is inves- tigated to evaluate the in-plane buckling load. The virtual work principle method is used to establish the non-linear equilibrium and buckling equations. Analytical solutions for the non-linear in-plane sym- metric snap-through and antisymmetric bifurcation buckling loads are obtained. Based on the least square method, an approximation for the symmetric buckling load of fixed parabolic arch is proposed to simplify the solution process. And the relation between modified slenderness and buckling modes are discussed. Comparisons with the results of finite element analysis demonstrate that the solutions are accurate. A cable-arch structure is presented to improve the in-plane stability of parabolic arches. The comparison of buckling loads between cable-arch systems and arches only show that the effect of cables becomes more evident with the increase of arch’s modified slenderness.

  13. Steiner Minimal Trees in Rectilinear and Octilinear Planes

    Institute of Scientific and Technical Information of China (English)

    Song Pu SHANG; Tong JING

    2007-01-01

    This paper considers the Steiner Minimal Tree (SMT) problem in the rectilinear and octi-linear planes. The study is motivated by the physical design of VLSI: The rectilinear case corresponds to the currently used M-architecture, which uses either horizontal or vertical routing, while the octi- linear case corresponds to a new routing technique, X-architecture, that is based on the pervasive use of diagonal directions. The experimental studies show that the X-architecture demonstrates a length reduction of more than 10-20%. In this paper, we make a theoretical study on the lengths of SMTs in these two planes. Our mathematical analysis confirms that the length reduction is significant as the previous experimental studies claimed, but the reduction for three points is not as significant as for two points. We also obtain the lower and upper bounds on the expected lengths of SMTs in these two planes for arbitrary number of points.

  14. TOUGHENING OF FERROELECTRICS BY THE OUT-OF-PLANE POLING

    Institute of Scientific and Technical Information of China (English)

    杨卫; 方菲

    2003-01-01

    Subjected to the prior out-of-plane poling, the ferroelectrics can be toughened considerably. The present paper describes the variation of the stress intensity factor (SIF) by 90° switching in ferroelectrics. The analysis is carried out for the combined mechanical and electrical loading, with simple relations obtained for the case of the purely electrical loading. The out-of-plane poling is found to raise the SIF for the crack initiation, but appreciably reduces the SIF for the crack growth in a steady state. More stable fracture resistance curves can be achieved by the out-of-plane poling. This prediction is supported quantitatively by the testing data of SENB specimens of PZT-5 samples, when the toughening effects of polings in three orthogonal directions are compared.

  15. Large molecular cloud in Lupus far from the Galactic plane

    Energy Technology Data Exchange (ETDEWEB)

    Nyman, L.A.; Thaddeus, P.; Bronfman, L.; Cohen, R.S.

    1987-03-01

    The detection of a large molecular cloud at a distance of more than 200 pc from the Galactic plane, situated above a prominent hole in the CO distribution in the plane, is reported. The cloud has a radial velocity of -41 km/s, much larger than is characteristic of most local, high-latitude gas. The cloud's displacement above the plane is the largest for any cloud yet detected. The mass of the cloud is about 100,000 solar masses, and its gravitational potential energy is about 7 x 10 to the 50th ergs. A single event may have created both the cloud and the nearby hole. 27 references.

  16. LiteBIRD: Mission Overview and Focal Plane Layout

    Science.gov (United States)

    Matsumura, T.; Akiba, Y.; Arnold, K.; Borrill, J.; Chendra, R.; Chinone, Y.; Cukierman, A.; de Haan, T.; Dobbs, M.; Dominjon, A.; Elleflot, T.; Errard, J.; Fujino, T.; Fuke, H.; Goeckner-wald, N.; Halverson, N.; Harvey, P.; Hasegawa, M.; Hattori, K.; Hattori, M.; Hazumi, M.; Hill, C.; Hilton, G.; Holzapfel, W.; Hori, Y.; Hubmayr, J.; Ichiki, K.; Inatani, J.; Inoue, M.; Inoue, Y.; Irie, F.; Irwin, K.; Ishino, H.; Ishitsuka, H.; Jeong, O.; Karatsu, K.; Kashima, S.; Katayama, N.; Kawano, I.; Keating, B.; Kibayashi, A.; Kibe, Y.; Kida, Y.; Kimura, K.; Kimura, N.; Kohri, K.; Komatsu, E.; Kuo, C. L.; Kuromiya, S.; Kusaka, A.; Lee, A.; Linder, E.; Matsuhara, H.; Matsuoka, S.; Matsuura, S.; Mima, S.; Mitsuda, K.; Mizukami, K.; Morii, H.; Morishima, T.; Nagai, M.; Nagasaki, T.; Nagata, R.; Nakajima, M.; Nakamura, S.; Namikawa, T.; Naruse, M.; Natsume, K.; Nishibori, T.; Nishijo, K.; Nishino, H.; Nitta, T.; Noda, A.; Noguchi, T.; Ogawa, H.; Oguri, S.; Ohta, I. S.; Otani, C.; Okada, N.; Okamoto, A.; Okamoto, A.; Okamura, T.; Rebeiz, G.; Richards, P.; Sakai, S.; Sato, N.; Sato, Y.; Segawa, Y.; Sekiguchi, S.; Sekimoto, Y.; Sekine, M.; Seljak, U.; Sherwin, B.; Shinozaki, K.; Shu, S.; Stompor, R.; Sugai, H.; Sugita, H.; Suzuki, T.; Suzuki, A.; Tajima, O.; Takada, S.; Takakura, S.; Takano, K.; Takei, Y.; Tomaru, T.; Tomita, N.; Turin, P.; Utsunomiya, S.; Uzawa, Y.; Wada, T.; Watanabe, H.; Westbrook, B.; Whitehorn, N.; Yamada, Y.; Yamasaki, N.; Yamashita, T.; Yoshida, M.; Yoshida, T.; Yotsumoto, Y.

    2016-04-01

    LiteBIRD is a proposed CMB polarization satellite project to probe the inflationary B-mode signal. The satellite is designed to measure the tensor-to-scalar ratio with a 68 % confidence level uncertainty of σ _r<10^{-3} , including statistical, instrumental systematic, and foreground uncertainties. LiteBIRD will observe the full sky from the second Lagrange point for 3 years. We have a focal plane layout for observing frequency coverage that spans 40-402 GHz to characterize the galactic foregrounds. We have two detector candidates, transition-edge sensor bolometers and microwave kinetic inductance detectors. In both cases, a telecentric focal plane consists of approximately 2× 10^3 superconducting detectors. We will present the mission overview of LiteBIRD, the project status, and the TES focal plane layout.

  17. Plane symmetric thin-shell wormholes: solutions and stability

    CERN Document Server

    Lemos, José P S

    2008-01-01

    Using the cut-and-paste procedure, we construct static and dynamic plane symmetric wormholes by surgically grafting together two spacetimes of plane symmetric vacuum solutions with a negative cosmological constant. These plane symmetric wormholes may be viewed as domain walls connecting different universes, having planar topology, and upon compactification of one or two coordinates, cylindrical topology or toroidal topology, respectively. A stability analysis is carried out for the dynamic case by taking into account specific equations of state, and a linearized stability analysis around static solutions is also explored. It is found that thin shell wormholes made of a dark energy fluid or of a cosmological constant fluid are stable, while thin shell wormholes made of phantom energy are unstable.

  18. Thickness and in-plane elasticity of graphane

    International Nuclear Information System (INIS)

    Highlights: → Determination of the thickness for 100% hydrogenated graphene (graphane). → Determination of mechanical in-plane special orthotropy of graphane. → Determination of the in-plane shear modulus of graphane. - Abstract: The thickness and in-plane mechanical properties (Young's, shear modulus, Poisson's ratios) of fully hydrogenated graphene (graphane) sheets are predicted using a molecular mechanics approach. The equilibrium lengths and bond angles distortions used for the graphane models are obtained from Density Functional Theory (DFT) simulations. Our models compare well with existing data on the uniaxial properties of graphane and graphene sheets from first principle and Molecular Dynamics (MD) simulations, highlight a special orthotropic mechanical behaviour for graphane, and identify thickness and shear stiffness values which are peculiar of hydrogenated graphene.

  19. Measure Guideline: Guidance on Taped Insulating Sheathing Drainage Planes

    Energy Technology Data Exchange (ETDEWEB)

    Grin, A. [Building Science Corporation, Somerville, MA (United States); Lstiburek, J. [Building Science Corporation, Somerville, MA (United States)

    2014-09-01

    The goal of this research is to provide durable and long-term water management solutions using exterior insulating sheathing as part of the water management system. It is possible to tape or seal the joints in insulating sheathing to create a drainage plane and even an air control layer. There exists the material durability component of the tape as well as the system durability component being the taped insulating sheathing as the drainage plane. This measure guideline provides best practice and product recommendations from the interviewed contractors and homebuilders who collectively have a vast amount of experience. Three significant issues were discussed with the group, which are required to make taped insulating sheathing a simple, long-term, and durable drainage plane: horizontal joints should be limited or eliminated wherever possible; where a horizontal joint exists use superior materials; and frequent installation inspection and regular trade training are required to maintain proper installation.

  20. In-plane charge dynamics in underdoped YBCO

    International Nuclear Information System (INIS)

    We report on the in-plane optical spectra in underdoped YBa2Cu3O7 (YBCO) using a twin-free single crystal. At low temperatures, there exist two components in the optical conductivity which are considered as a Drude term by quasiparticles in a nodal direction and the pseudogap excitation in an antinodal direction. A large residual conductivity together with pseudogap feature is consistent with the picture of inhomogeneous in-plane electronic state observed by scanning tunneling microscopy (STM). We estimate a superfluid density n s from optical spectra and discuss a universal relation between T c and n s. The value estimated from our results is considerably smaller than that of the μSR measurement. It is considered due to the inhomogeneity of in-plane, the difference of applying field, and a property on pseudogap

  1. CLAES focal plane array. [Cryogenic Limb Array Etalon Spectrometer

    Science.gov (United States)

    Roche, A. E.; Sterritt, L. W.; Kumer, J. B.; Callary, P. C.; Nielsen, R. L.

    1989-01-01

    The Cryogenic Limb Array Etalon Spectrometer for the NASA Upper Atmospheric Research Satellite uses solid-state focal plane arrays to detect emission from the earth's atmosphere over the IR wavelength range 3.5 to 13 microns. This paper discusses the design of the focal plane detector assembly and compares calculated performance with measurements. Measurements were made of focal plane noise and responsivity as functions of frequency (2 to 500 Hz) and temperature (12 to 19 K), pixel-to-pixel and across-array crosstalk, and linearity over a dynamic range of 100,000. The measurements demonstrate that the arrays satisfy the science requirements, and that, in general, there is reasonable agreement between the measurements and the analytical model.

  2. LiteBIRD: Mission Overview and Focal Plane Layout

    Science.gov (United States)

    Matsumura, T.; Akiba, Y.; Arnold, K.; Borrill, J.; Chendra, R.; Chinone, Y.; Cukierman, A.; de Haan, T.; Dobbs, M.; Dominjon, A.; Elleflot, T.; Errard, J.; Fujino, T.; Fuke, H.; Goeckner-wald, N.; Halverson, N.; Harvey, P.; Hasegawa, M.; Hattori, K.; Hattori, M.; Hazumi, M.; Hill, C.; Hilton, G.; Holzapfel, W.; Hori, Y.; Hubmayr, J.; Ichiki, K.; Inatani, J.; Inoue, M.; Inoue, Y.; Irie, F.; Irwin, K.; Ishino, H.; Ishitsuka, H.; Jeong, O.; Karatsu, K.; Kashima, S.; Katayama, N.; Kawano, I.; Keating, B.; Kibayashi, A.; Kibe, Y.; Kida, Y.; Kimura, K.; Kimura, N.; Kohri, K.; Komatsu, E.; Kuo, C. L.; Kuromiya, S.; Kusaka, A.; Lee, A.; Linder, E.; Matsuhara, H.; Matsuoka, S.; Matsuura, S.; Mima, S.; Mitsuda, K.; Mizukami, K.; Morii, H.; Morishima, T.; Nagai, M.; Nagasaki, T.; Nagata, R.; Nakajima, M.; Nakamura, S.; Namikawa, T.; Naruse, M.; Natsume, K.; Nishibori, T.; Nishijo, K.; Nishino, H.; Nitta, T.; Noda, A.; Noguchi, T.; Ogawa, H.; Oguri, S.; Ohta, I. S.; Otani, C.; Okada, N.; Okamoto, A.; Okamoto, A.; Okamura, T.; Rebeiz, G.; Richards, P.; Sakai, S.; Sato, N.; Sato, Y.; Segawa, Y.; Sekiguchi, S.; Sekimoto, Y.; Sekine, M.; Seljak, U.; Sherwin, B.; Shinozaki, K.; Shu, S.; Stompor, R.; Sugai, H.; Sugita, H.; Suzuki, T.; Suzuki, A.; Tajima, O.; Takada, S.; Takakura, S.; Takano, K.; Takei, Y.; Tomaru, T.; Tomita, N.; Turin, P.; Utsunomiya, S.; Uzawa, Y.; Wada, T.; Watanabe, H.; Westbrook, B.; Whitehorn, N.; Yamada, Y.; Yamasaki, N.; Yamashita, T.; Yoshida, M.; Yoshida, T.; Yotsumoto, Y.

    2016-08-01

    LiteBIRD is a proposed CMB polarization satellite project to probe the inflationary B-mode signal. The satellite is designed to measure the tensor-to-scalar ratio with a 68 % confidence level uncertainty of σ _rstatistical, instrumental systematic, and foreground uncertainties. LiteBIRD will observe the full sky from the second Lagrange point for 3 years. We have a focal plane layout for observing frequency coverage that spans 40-402 GHz to characterize the galactic foregrounds. We have two detector candidates, transition-edge sensor bolometers and microwave kinetic inductance detectors. In both cases, a telecentric focal plane consists of approximately 2× 10^3 superconducting detectors. We will present the mission overview of LiteBIRD, the project status, and the TES focal plane layout.

  3. Event-plane flow analysis without non-flow effects

    CERN Document Server

    Bilandzic, Ante; Ollitrault, Jean-Yves; Snellings, Raimond

    2008-01-01

    The event-plane method, which is widely used to analyze anisotropic flow in nucleus-nucleus collisions, is known to be biased by nonflow effects,especially at high $p_t$. Various methods (cumulants, Lee-Yang zeroes) have been proposed to eliminate nonflow effects, but their implementation is tedious, which has limited their application so far. In this paper, we show that the Lee-Yang-zeroes method can be recast in a form similar to the standard event-plane analysis. Nonflow correlations are eliminated by using the information from the length of the flow vector, in addition to the event-plane angle. This opens the way to improved analyses of elliptic flow and azimuthally-sensitive observables at RHIC and LHC.

  4. Surface polaritons in symmetry planes of biaxial crystals

    Energy Technology Data Exchange (ETDEWEB)

    Furs, A N; Galynsky, V M; Barkovsky, L M [Department of Theoretical Physics, Belarussian State University, Fr. Skarina Ave. 4, Minsk 220050 (Belarus)

    2005-09-16

    The problem of the surface polariton existence in symmetry planes of non-magnetic biaxial crystals is studied theoretically. The plane interface of such a crystal and a semi-infinite isotropic medium is considered. With the use of the integral formalism formulated in our earlier work, the dispersion equation is derived for the polaritons under consideration. The existence conditions for the dispersion equation solutions are obtained in the form of algebraic inequalities for principal values of inverse dielectric permittivity tensors. If these conditions are satisfied, then excitation of surface waves is possible along the allowed propagation directions, which constitute sectors in the interface plane. Exact expressions are obtained that determine location of these sectors with respect to the symmetry axes of the crystal.

  5. Uncooled infrared sensors with digital focal plane array

    Science.gov (United States)

    Marshall, Charles A.; Butler, Neal R.; Blackwell, Richard; Murphy, Robert; Breen, Thomas

    1996-06-01

    Loral Infrared & Imaging Systems is developing low cost, high performance, uncooled infrared imaging products for both military and commercial applications. These products are based on the microbolometer technology, a silicon micromachined sensor which combines the wafer level silicon processing with a device structure capable of yielding excellent infrared imaging performance. Here, we report on the development of an uncooled sensor, the LTC500, which incorporates an all digital focal plane array and has a measured NETD of less than 70 mK. The focal plane array and the electronics within the LTC500 have been designed as an integrated unit to meet a broad range of end user applications by providing features such as nonuniformity correction, autogain and level, NTSC video, and digital outputs. The 327 X 245 element focal plane array has a 46.25 micrometers pixel pitch and an on focal plane array 14 bit to analog to digital converter (ADC). The ADC has a measured instantaneous dynamic range of more than 76 dB at a 6.1 MHz output data rate and 60 Hz frame rate. The focal plane array consumes less than 500 mW of power, of which less than 250 mW is used in the ADC. An additional 36 dB of digital coarse offset correction in front of the ADC on the focal plane array results in a total electronic dynamic range of 112 dB. The MRT of the LTC500 camera has been measured at less 0.2 C at f(subscript o).

  6. Evaluation of planar 3D electrical capacitance tomography: from single-plane to dual-plane configuration

    International Nuclear Information System (INIS)

    Electrical capacitance tomography (ECT) is a non-invasive imaging technique that is sensitive to the dielectric permittivity property of an object. Conventional ECT systems have a circular/cylindrical or rectangular geometry, in which the electrode plates are usually spaced equally around the tank. It is the most common configuration as it can be easily applied to industrial pipelines. However, under some circumstances, the full access to the imaging geometry may not be applicable due to the limitation of the process area. In those cases, and with limited access, planar ECT sensors can fit the process structure if access to only one side is possible. A single-plane ECT configuration has been proposed for such applications. However, the planar array often suffers from a lack of sensitivity and difficulty with depth detection. To better understand these limitations we investigate the imaging performance from the single-plane ECT to dual-plane ECT structure. The limitations and constraints of the planar configuration will also be discussed. Several experiments were conducted using both single-plane and dual-plane configurations to evaluate the potential applications. The initial results are promising, and the quality of the reconstructed images are compared with the real condition for process validation. (paper)

  7. Competition between invariant habit plane and compatible junction plane in TiNb-based shape memory alloy

    International Nuclear Information System (INIS)

    Highlights: ► Kinematic compatibility (KC) among martensite variants in Ti-Nb-Al is evaluated. ► Rotation Q is necessary to keep KC at any junction plane (JP). ► The rotation Q is equivalent to the rotation to form the exact twin-relationship. ► The JP preferentially observed in experiment is the JP with the smaller Q. ► We propose two preferential JPs with {1 1 1} type I and 〈2 1 1〉 type II twin in Ti-Nb-Al. -- Abstract: The invariant plane (IP) condition at a habit plane (HP) and the kinematic compatibility (KC) condition at a junction plane (JP) are quantitatively evaluated by the geometrically nonlinear theory of martensite and the origin of the twin orientation relationship (OR) at a JP is revealed in a β titanium shape memory alloy. Exact twin OR at a JP is impossible among the habit plane variants (HPVs). A nonzero rotation is necessary to maintain the compatibility at a JP between the HPVs. The fully compatible HPV cluster in which IP at a HP and KC at a JP are maintained simultaneously is impossible in this alloy. However, it was found that twin OR and KC can be maintained simultaneously. The preferentially observed HPV clusters in transmission electron microscopy are the clusters with a smaller rotation to maintain KC at a JP

  8. Competition between invariant habit plane and compatible junction plane in TiNb-based shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Inamura, T., E-mail: inamura.t.aa@m.titech.ac.jp [Precision and Intelligence Laboratory, Tokyo Institute of Technology (Japan); Kim, H.Y. [Institute of Materials Science, University of Tsukuba (Japan); Hosoda, H. [Precision and Intelligence Laboratory, Tokyo Institute of Technology (Japan); Miyazaki, S. [Institute of Materials Science, University of Tsukuba (Japan)

    2013-11-15

    Highlights: ► Kinematic compatibility (KC) among martensite variants in Ti-Nb-Al is evaluated. ► Rotation Q is necessary to keep KC at any junction plane (JP). ► The rotation Q is equivalent to the rotation to form the exact twin-relationship. ► The JP preferentially observed in experiment is the JP with the smaller Q. ► We propose two preferential JPs with {1 1 1} type I and 〈2 1 1〉 type II twin in Ti-Nb-Al. -- Abstract: The invariant plane (IP) condition at a habit plane (HP) and the kinematic compatibility (KC) condition at a junction plane (JP) are quantitatively evaluated by the geometrically nonlinear theory of martensite and the origin of the twin orientation relationship (OR) at a JP is revealed in a β titanium shape memory alloy. Exact twin OR at a JP is impossible among the habit plane variants (HPVs). A nonzero rotation is necessary to maintain the compatibility at a JP between the HPVs. The fully compatible HPV cluster in which IP at a HP and KC at a JP are maintained simultaneously is impossible in this alloy. However, it was found that twin OR and KC can be maintained simultaneously. The preferentially observed HPV clusters in transmission electron microscopy are the clusters with a smaller rotation to maintain KC at a JP.

  9. Combinatorics associated with inflections and bitangents of plane quartics

    International Nuclear Information System (INIS)

    After a preliminary survey and a description of some small Steiner systems from the standpoint of the theory of invariants of binary forms, we construct a binary Golay code (of length 24) using ideas from J. Grassmann's thesis of 1875. One of our tools is a pair of disjoint Fano planes. Another application of such pairs and properties of plane quartics is a construction of a new block design on 28 objects. This block design is a part of a dissection of the set of 288 Aronhold sevens. The dissection distributes the Aronhold sevens into 8 disjoint block designs of this type

  10. Locating a general minisum 'circle' on a plane

    DEFF Research Database (Denmark)

    Brimberg, Jack; Juel, Henrik; Körner, Mark-Christoph;

    2011-01-01

    We approximate a set of given points in the plane by the boundary of a convex and symmetric set which is the unit circle of some norm. This generalizes previous work on the subject which considers Euclidean circles only. More precisely, we examine the problem of locating and scaling the unit circle...... of some given norm k with respect to given points on the plane such that the sum of weighted distances (as measured by the same norm k) between the circumference of the circle and the points is minimized. We present general results and are able to identify a finite dominating set in the case that k...

  11. Locating a circle on the plane using the minimax criterion

    DEFF Research Database (Denmark)

    Brimberg, Jack; Juel, Henrik; Schöbel, Anita

    2009-01-01

    We consider the problem of locating a circle with respect to existing facilities on the plane, such that the largest weighted distance between the circumference of the circle and the facilities is minimized. The problem properties are analyzed, and a solution procedure proposed......We consider the problem of locating a circle with respect to existing facilities on the plane, such that the largest weighted distance between the circumference of the circle and the facilities is minimized. The problem properties are analyzed, and a solution procedure proposed...

  12. VERTICAL DISTRIBUTION OF LONGSHORE CURRENTS OVER PLANE AND BARRED BEACHES

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhen-wei; ZOU Zhi-li

    2012-01-01

    Experiments were conducted to determine the vertical profile of the longshore currents over plane and barred beaches.The logarithmic law is applied to fit the data for the region below the wave trough and an adjusted logarithmic profile without the mass transport velocity is applied to the region above the wave trough.The results indicate that the logarithmic law fits the data well for both plane and barred beaches.The friction velocity and the relative roughness obtained by the data fitting are compared with relevant calculated results.

  13. Out-of-plane auxeticity in sintered fibre network mats

    International Nuclear Information System (INIS)

    Fibre network mats composed of stainless steel exhibit an unusually large out-of-plane auxeticity (i.e. high negative Poisson’s ratio ν) when subjected to in-plane tensile loading. In situ observations in a scanning electron microscope suggest that this is attributable to fibre segment straightening. An investigation was carried out on the effects of fibre volume fraction and network thickness on the auxetic response. Weak inter-layer bonding, high fibre content and low network thickness were found to amplify the auxetic effect

  14. Boxed skew plane partition and integrable phase model

    International Nuclear Information System (INIS)

    We study the relation between the boxed skew plane partition and the integrable phase model. We introduce a generalization of a scalar product of the phase model and calculate it in two ways: the first one in terms of the skew Schur functions, and the other one by use of the commutation relations of operators. In both cases, a generalized scalar product is expressed as a determinant. We show that a special choice of the spectral parameters of a generalized scalar product gives the generating function of the boxed skew plane partition

  15. Strings in RR Plane Wave Background at Finite Temperature

    OpenAIRE

    Zayas, Leopoldo A. Pando; Vaman, Diana

    2002-01-01

    We calculate the thermal partition function in the canonical ensemble for type IIB superstrings in the plane wave background with constant null R-R 5-form. The Hagedorn temperature is found to be higher than the corresponding value for strings in flat space. In the limit corresponding to the weakly coupled field theory we find that the Hagedorn temperature is pushed to infinity. The key property of strings in the plane wave background under investigation on which our result relies is that the...

  16. The bolometric focal plane array of the Polarbear CMB experiment

    CERN Document Server

    Arnold, K; Anthony, A E; Barron, D; Boettger, D; Borrill, J; Chapman, S; Chinone, Y; Dobbs, M A; Errard, J; Fabbian, G; Flanigan, D; Fuller, G; Ghribi, A; Grainger, W; Halverson, N; Hasegawa, M; Hattori, K; Hazumi, M; Holzapfel, W L; Howard, J; Hyland, P; Jaffe, A; Keating, B; Kermish, Z; Kisner, T; Jeune, M Le; Lee, A T; Linder, E; Lungu, M; Matsuda, F; Matsumura, T; Miller, N J; Meng, X; Morii, H; Moyerman, S; Myers, M J; Nishino, H; Paar, H; Quealy, E; Reichardt, C; Richards, P L; Ross, C; Shimizu, A; Shimmin, C; Shimon, M; Sholl, M; Siritanasak, P; Spieler, H; Stebor, N; Steinbach, B; Stompor, R; Suzuki, A; Tomaru, T; Tucker, C; Zahn, O

    2012-01-01

    The Polarbear Cosmic Microwave Background (CMB) polarization experiment is currently observing from the Atacama Desert in Northern Chile. It will characterize the expected B-mode polarization due to gravitational lensing of the CMB, and search for the possible B-mode signature of inflationary gravitational waves. Its 250 mK focal plane detector array consists of 1,274 polarization-sensitive antenna-coupled bolometers, each with an associated lithographed band-defining filter. Each detector's planar antenna structure is coupled to the telescope's optical system through a contacting dielectric lenslet, an architecture unique in current CMB experiments. We present the initial characterization of this focal plane.

  17. Solitonlike solutions of magnetostatic equilibria: Plane-symmetric case

    CERN Document Server

    Yoshino, Hirotaka

    2008-01-01

    We present the plane-symmetric solitonlike solutions of magnetostatic equilibria by solving the nonlinear Grad-Shafranov (GS) equation numerically. The solutions have solitonlike and periodic structures in the $x$ and $y$ directions, respectively, and $z$ is the direction of plane symmetry. Although such solutions are unstable against the numerical iteration, we give the procedure to realize the sufficient convergence. Our result provides the definite answer for the existence of the solitonlike solutions that was questioned in recent years. The method developed in this paper will make it possible to study the axisymmetric solitonlike solutions of the nonlinear GS equation, which could model astrophysical jets with knotty structures.

  18. Plane extraction and error modeling of 3D data

    OpenAIRE

    Viejo Hernando, Diego; Cazorla Quevedo, Miguel Ángel

    2006-01-01

    We are interested in using natural landmarks obtained by a stereo system not only in SLAM-like algorithms but also feature extraction, map building, and so on. Using a stereo camera we can extract planes and geometrical primitives like that. In order to use these primitives a perceptual model of landmarks is needed, due to error model can improve the results. In this paper we present a method to get the perceptual model of the plane extraction process. We will show that the use of this ...

  19. Percutaneous sagittal plane closing wedge osteotomy of the first metatarsal.

    Science.gov (United States)

    Lui, Tun Hing

    2014-02-01

    Osteotomy of the first metatarsal in the sagittal plane is useful in correction of numerous deformity of the foot. Plantarflexion osteotomy of the first metatarsal can be used to treat hallux rigidus, hallux limitus, forefoot varus in flatfoot deformity and iatrogenic metatarsus primus elevates. Dorsiflexion osteotomy of the first metatarsal is an important component in surgical correction of pes cavus. It is also indicated in recalcitrant diabetic neuropathic ulcers at the first metatarsal head. We described a minimally invasive technique of sagittal plane corrective osteotomy of the first metatarsal, which can be either a plantarflexion or dorsiflexion one. PMID:23412315

  20. Kinematics of line-plane subassemblies in Stewart platforms

    OpenAIRE

    Borràs, Julia; Thomas, Federico

    2009-01-01

    When the attachments of five legs in a Stewart platform are collinear on one side and coplanar on the other, the platform is said to contain a line-plane subassembly. This paper is devoted to the kinematics analysis of this subassembly paying particular attention to the problem of moving the aforementioned attachments without altering the singularity locus of the platform. It is shown how this is always possible provided that some cross-ratios between lines - defined by points in the plane- a...

  1. A Geometric Interpretation of Half-Plane Capacity

    OpenAIRE

    Lalley, Steven,; Lawler, Gregory; Narayanan, Hariharan

    2009-01-01

    Let A be a bounded, relatively closed subset of the upper half plane H whose complement C is simply connected. If B_t is a standard complex Brownian motion starting at iy and t_A = inf {t > 0: B_t not in C}, the half-plane capacity of A, hcap(A) is defined to be the limit as y goes to infinity of y E[Im(B_{t_A}]. This quantity arises naturally in the study of Schramm-Loewner Evolutions (SLE). In this note, we show that hcap(A) is comparable to a more geometric quantity hsiz(A) that we define ...

  2. Minimally Actuated Dynamic Climbing in the Sagittal Plane

    OpenAIRE

    Birkmeyer, Paul Michael

    2013-01-01

    This thesis explores the design of systems that can climb vertical surfaces with non-negligible dynamics in the sagittal plane. The development of a low-dimensional model addresses a lack of understanding of sagittal plane dynamics during climbing in the space of reduced-order dynamic models of legged systems. Using a construction derived from the well-known and well-studied Spring-Loaded Inverted Pendulum (SLIP), we propose a two-legged system with both torsional and linear compliance driven...

  3. Null weak singularities in plane-symmetric spacetimes

    CERN Document Server

    Ori, A

    1998-01-01

    We construct a new class of plane-symmetric solutions possessing a curvature singularity which is null and weak, like the spacetime singularity at the Cauchy horizon of spinning (or charged) black holes. We then analyse the stability of this singularity using a rigorous non-perturbative method. We find that within the framework of (linearly-polarized) plane-symmetric spacetimes this type of null weak singularity is locally stable. Generically, the singularity is also scalar-curvature. These observations support the new picture of the null weak singularity inside spinning (or charged) black holes, which is so far established primarily on the perturbative approach.

  4. Sasa-Satsuma equation, unstable plane waves and heteroclinic connections

    International Nuclear Information System (INIS)

    The Sasa-Satsuma equation is an integrable perturbation of the nonlinear Schroedinger equation which models the effects of third-order dispersion, self-steepening and stimulated Raman scattering in the propagation of ultra-fast pulses in optical fiber transmission systems. The heteroclinic connections of the unstable plane waves are explicitly constructed using an auto-Baecklund transformation obtained from inverse spectral theory. The modulus of the heteroclinic connection can have either a single peak or a double peak, depending on the amplitude of the unstable plane wave, even when only one unstable positive wavenumber is present

  5. Interfacial Refraction Through Curved and Plane-Layered Media

    Energy Technology Data Exchange (ETDEWEB)

    Kehoe, A.B.

    2001-07-17

    Two laser beam tracing codes, AXIAL and CYLINDER, have been written to determine a laser beam path through plane and cylindrical interfaces. For cylindrical interfaces, an equation set was derived which describes the path of the laser beam. For plane interfaces, it was not possible to derive a single equation set. Instead, it was necessary to divide the domain up into small elements or regions. The laser beam path was then determined by calculating the path of the laser beam through each region. AXIAL and CYLINDER can be used to determine where an LDA should be positioned so that velocity measurements can be made at a specified point.

  6. Comb-Line Filter with Coupling Capacitor in Ground Plane

    Directory of Open Access Journals (Sweden)

    Toshiaki Kitamura

    2011-01-01

    Full Text Available A comb-line filter with a coupling capacitor in the ground plane is proposed. The filter consists of two quarter-wavelength microstrip resonators. A coupling capacitor is inserted into the ground plane in order to build strong coupling locally along the resonators. The filtering characteristics are investigated through numerical simulations as well as experiments. Filtering characteristics that have attenuation poles at both sides of the passband are obtained. The input susceptances of even and odd modes and coupling coefficients are discussed. The filters using stepped impedance resonators (SIRs are also discussed, and the effects of the coupling capacitor for an SIR structure are shown.

  7. Field Theory for Function Fields of Plane Quintic Curves

    Institute of Scientific and Technical Information of China (English)

    Kei Miura

    2002-01-01

    We study the structure of function fields of plane curves following our method developed in [3]. Let K be the function field of a smooth plane curve C.Let Km be a g-maximal rational subfield of K. Then the field extension K/Km is obtained by the projection from C to a line with center P ∈ C. By using this fact, we study the field extension K/Km from a geometrical viewpoint. In this paper, we treat quintic curves as a continuation of [3, 4].

  8. Plane waves and spherical means applied to partial differential equations

    CERN Document Server

    John, Fritz

    2004-01-01

    Elementary and self-contained, this heterogeneous collection of results on partial differential equations employs certain elementary identities for plane and spherical integrals of an arbitrary function, showing how a variety of results on fairly general differential equations follow from those identities. The first chapter deals with the decomposition of arbitrary functions into functions of the type of plane waves. Succeeding chapters introduce the first application of the Radon transformation and examine the solution of the initial value problem for homogeneous hyperbolic equations with con

  9. Plane waves in a thermally conducting viscous liquid

    Indian Academy of Sciences (India)

    Baljeet Singh

    2004-02-01

    The aim of this paper is to investigate plane waves in a thermally conducting viscous liquid half-space with thermal relaxation times. There exist three basic waves, namely; thermal wave, longitudinal wave and transverse wave in a thermally conducting viscous liquid half-space. Reflection of plane waves from the free surface of a thermally conducting viscous liquid half-space is studied. The results are obtained in terms of amplitude ratios and are compared with those without viscosity and thermal disturbances.

  10. Waveguide e-plane all-metal inserted diplexer

    OpenAIRE

    Rakić Milica; Jokanović Branka; Budimir Đ.

    2004-01-01

    This paper presents the procedure for designing a wave guide E-plane diplexer for Ku band with inserted metal septa. The diplexer is designed with filters of the fifth order and with T-junction in E-plane for the purpose of easier integration with microwave transceiver. The aim of this work is to master the design of a diplexer that should obtain 60 dB insulation between receiver and transmitter of a radio link and that will not need to be adjusted in serial production.

  11. Waveguide e-plane all-metal inserted diplexer

    Directory of Open Access Journals (Sweden)

    Rakić Milica

    2004-01-01

    Full Text Available This paper presents the procedure for designing a wave guide E-plane diplexer for Ku band with inserted metal septa. The diplexer is designed with filters of the fifth order and with T-junction in E-plane for the purpose of easier integration with microwave transceiver. The aim of this work is to master the design of a diplexer that should obtain 60 dB insulation between receiver and transmitter of a radio link and that will not need to be adjusted in serial production.

  12. Stress and morphology of a nonpolar a-plane GaN layer on r-plane sapphire substrate

    Institute of Scientific and Technical Information of China (English)

    Xu Sheng-Rui; He Qiang; Lii Ling; Hao Yue; Zhang Jin-Cheng; XueXiao-Yong; Li Pei-Xian; Li Jian-Ting; Lin Zhi-Yu; Liu Zi-Yang; Ma Jun-Cai

    2011-01-01

    The anisotropic strain of a nonpolar (11(2)0) a-plane GaN epilayer on an r-plane (1(1)02) sapphire substrate,grown by low-pressure metal-organic vapour deposition is investigated by Raman spectroscopy.The room-temperature Raman scattering spectra of nonpolar a-plane GaN are measured in surface and edge backscattering geometries.The lattice is contracted in both the c- and the m-axis directions,and the stress in the m-axis direction is larger than that in the c-axis direction.On the surface of this sample,a number of cracks appear only along the m-axis,which is confirmed by the scanning electron micrograph.Atomic force microscopy images reveal a significant decrease in the root-mean-square roughness and the density of submicron pits after the stress relief.

  13. Petroleum exploration potential in abyssal zone of Qiongdongnan Basin, South China Sea%南海琼东南盆地深水区油气勘探潜力

    Institute of Scientific and Technical Information of China (English)

    朱廷祥; 段铁军

    2012-01-01

    南海琼东南盆地经历了始新世的陆内断陷、渐新世的裂谷和中新世以来的被动陆缘坳陷等3个演化阶段,特别是在深水区形成了断陷期湖相、裂谷期海陆过渡相到海相及被动陆缘坳陷期海相等多套生烃物质;3期构造沉降作用伴随了3次高热流事件,利于烃源岩的成熟;多储集体类型、多套储盖组合,为油气富集提供了广阔的空间;多期构造运动,形成多种圈闭类型,利于油气聚集成藏.%The evolution of the Qiongdongnan Basin in the South China Sea can be divided into three stages including intracontinental rift during Eocene, rift during Oligocene, and passive continental margin depression ever since Miocene. Multiple sets of petroleum generating materials of different facies were deposited in abyssal zone. For example, lacustrine facies in the first stage, marine-continental and continental facies in the second stage, and marine facies in the third stage. Three high thermal fluid events took place during the three evolution stages, contributing to the maturation of source rocks. Multiple types of reservoir and multiple sets of reservoir - cap assemblage provided abundant room for the enrichment of petroleum. Various types of trap formed during stages of tectonic movements were favorable for accumulation.

  14. Transition from in-plane to out-of-plane azimuthal enhancement in Au+Au collisions

    CERN Document Server

    Andronic, A; Petrovici, M; Simion, V; Crochet, Philippe; Alard, J P; Averbeck, R; Barret, V; Basrak, Z; Bastid, N; Bendarag, A; Berek, G; Devismes, A; Dupieux, P; Dzelalija, M; Eskef, M; Finck, C; Fodor, Z; Gobbi, A; Grishkin, Yu L; Hartmann, O N; Herrmann, N; Hildenbrand, K D; Hong, B H; Kecskeméti, J; Kim, Y J; Kirejczyk, M; Korolija, M; Kotte, R; Kress, T; Kutsche, R; Lebedev, A; Lee, K S; Leifels, Y; Man'ko, V I; Merlitz, H; Neubert, W; Pelte, D; Plettner, C; Rami, F; Reisdorf, W; De Schauenburg, B; Schull, D; Seres, Z; Sikora, B; Sim, K S; Siwek-Wilczynska, K; Smolyankin, V T; Stockmeier, M R; Vasilev, M; Wagner, P; Wisniewski, K; Wohlfarth, D; Yushmanov, I E; Zhilin, A V

    2001-01-01

    The incident energy at which the azimuthal distributions in semi-central heavy ion collisions change from in-plane to out-of-plane enhancement, E_tran, is studied as a function of mass of emitted particles, their transverse momentum and centrality for Au+Au collisions. The analysis is performed in a reference frame rotated with the sidewards flow angle, Theta_flow, relative to the beam axis. A systematic decrease of E_tran as function of mass of the reaction products, their transverse momentum and collision centrality is evidenced. The predictions of a microscopic transport model (IQMD) are compared with the experimental results.

  15. Noncommutative Geometry: Fuzzy Spaces, the Groenewold-Moyal Plane

    Directory of Open Access Journals (Sweden)

    Aiyalam P. Balachandran

    2006-12-01

    Full Text Available In this talk, we review the basics concepts of fuzzy physics and quantum field theory on the Groenewold-Moyal Plane as examples of noncommutative spaces in physics. We introduce the basic ideas, and discuss some important results in these fields. At the end we outline some recent developments in the field.

  16. The plane strain tests in the PROMETRA program

    Science.gov (United States)

    Cazalis, B.; Desquines, J.; Carassou, S.; Le Jolu, T.; Bernaudat, C.

    2016-04-01

    A fuel cladding mechanical test, performed under conditions of plane strain deformation in the transverse direction of tube axis, was originally developed at Pennsylvania State University. It was decided to implement this original test within the PROMETRA program using the same experimental procedure and its optimization for a ring mechanical testing on plane strain conditions (PST tests) in hot cells laboratory. This paper presents a detailed description and an interpretation of the Plane Strain Tensile (PST) tests performed in the framework of the PROMETRA program on fresh and irradiated claddings. At first, the context of the PST tests is situated and the specificities of these tests implemented at CEA are justified. Indeed, a significant adjustment of the original experimental procedure is carried out in order to test the irradiated fuel cladding in the best possible conditions. Then, the tests results on fresh Zircaloy-4 and on irradiated Zircaloy-4, M5™ and ZIRLO® specimens are gathered. The main analyses in support of these tests, such as metallographies, fractographic examinations and finite element simulations are detailed. Finally, a synthesis of the interpretation of the tests is proposed. The PST test seems only representative of plane strain fracture conditions when the test material is very ductile (fresh or high temperature or low hydride material like M5TM). However, it provides a relevant representation of the RIA rupture initiation which is observed in irradiated cladding resulting from hydride rim damage due to the strong irradiation of a fuel rod.

  17. Facial rejuvenation with fillers: The dual plane technique

    Directory of Open Access Journals (Sweden)

    Giovanni Salti

    2015-01-01

    Full Text Available Background: Facial aging is characterized by skin changes, sagging and volume loss. Volume is frequently addressed with reabsorbable fillers like hyaluronic acid gels. Materials and Methods: From an anatomical point of view, the deep and superficial fat compartments evolve differently with aging in a rather predictable manner. Volume can therefore be restored following a technique based on restoring first the deep volumes and there after the superficial volumes. We called this strategy "dual plane". A series of 147 consecutive patients have been treated with fillers using the dual plane technique in the last five years. Results: An average of 4.25 session per patient has been carried out for a total of 625 treatment sessions. The average total amount of products used has been 12 ml per patient with an average amount per session of 3.75 ml. We had few and limited adverse events with this technique. Conclusion: The dual plane technique is an injection technique based on anatomical logics. Different types of products can be used according to the plane of injection and their rheology in order to obtain a natural result and few side effects.

  18. Observations with a mid-plane reciprocating probe in MAST

    International Nuclear Information System (INIS)

    A fast reciprocating probe has recently been installed on MAST. It has been used to measure the outboard, mid-plane scrape off layer (SOL) of L-mode plasmas, and to study the intermittent fluctuations in the SOL in L-mode and ELMy H-mode discharges. In this paper, the system and the experiments are introduced

  19. Topological and arithmetical properties of rational plane curves

    OpenAIRE

    Artal Bartolo, Enrique; Carmona Ruber, Jorge; Cogolludo Agustín, José Ignacio; Escario Gil, Mario; Fernández de Bobadilla de Olarzábal, Javier José; Luengo Velasco, Ignacio; Melle Hernández, Alejandro

    2004-01-01

    We study properties of arrangements of rational plane curves. The existence of such curves with prescribed topological data has a lot of geometric restrictions. We show how to use the theory of singular complex analytic spaces to obtain such restrictions. We also study topological properties of such arrangements

  20. Parallel eigensolvers in plane-wave Density Functional Theory

    CERN Document Server

    Levitt, Antoine

    2014-01-01

    We consider the problem of parallelizing electronic structure computations in plane-wave Density Functional Theory. Because of the limited scalability of Fourier transforms, parallelism has to be found at the eigensolver level. We show how a recently proposed algorithm based on Chebyshev polynomials can scale into the tens of thousands of processors, outperforming block conjugate gradient algorithms for large computations.

  1. The HIFI Focal Plane Beam Characterization and Alignment Status

    NARCIS (Netherlands)

    Jellema, Willem; Jochemsen, M.; Peacocke, T.; Meinsma, L.; Lowes, P.; Withington, S.; Wild, Wolfgang; Wild, W

    2008-01-01

    In this paper we present the results of the characterization program of the beams in the focal plane of the HIFI flight model. We discuss the beam properties, quality of alignment, instrument footprint, performance impact and compliance and compare the results to predictions based on lower-level cha

  2. Size-effects in plane strain sheet-necking

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Redanz, Pia

    2004-01-01

    A finite strain generalization of the strain gradient plasticity theory by Fleck and Hutchinson (J. Mech. Phys. Solids 49 (2001a) 2245) is proposed and used to study size effects in plane strain necking of thin sheets using the finite element method. Both sheets with rigid grips at the ends and...

  3. 3-D Velocity Estimation for Two Planes in vivo

    DEFF Research Database (Denmark)

    Holbek, Simon; Pihl, Michael Johannes; Ewertsen, Caroline;

    2014-01-01

    3-D velocity vectors can provide additional flow information applicable for diagnosing cardiovascular diseases e.g. by estimating the out-of-plane velocity component. A 3-D version of the Transverse Oscillation (TO) method has previously been used to obtain this information in a carotid flow...... stored on the experimental scanner SARUS. The full 3-D velocity profile can be created and examined at peak-systole and end-diastole without ECG gating in two planes. Maximum out-of-plane velocities for the three peak-systoles and end-diastoles were 68.5 5.1 cm/s and 26.3 3.3 cm/s, respectively. In the...... longitudinal plane, average maximum peak velocity in flow direction was 65.2 14.0 cm/s at peak-systole and 33.6 4.3 cm/s at end-diastole. A commercial BK Medical ProFocus UltraView scanner using a spectral estimator gave 79.3 cm/s and 14.6 cm/s for the same volunteer. This demonstrates that real-time 3-D...

  4. Quantum-Well Infrared Photodetector (QWIP) Focal Plane Assembly

    Science.gov (United States)

    Jhabvala, Murzy; Jhabvala, Christine A.; Ewin, Audrey J.; Hess, Larry A.; Hartmann, Thomas M.; La, Anh T.

    2012-01-01

    A paper describes the Thermal Infrared Sensor (TIRS), a QWIP-based instrument intended to supplement the Operational Land Imager (OLI) for the Landsat Data Continuity Mission (LDCM). The TIRS instrument is a far-infrared imager operating in the pushbroom mode with two IR channels: 10.8 and 12 microns. The focal plane will contain three 640x512 QWIP arrays mounted on a silicon substrate. The silicon substrate is a custom-fabricated carrier board with a single layer of aluminum interconnects. The general fabrication process starts with a 4-in. (approx.10-cm) diameter silicon wafer. The wafer is oxidized, a single substrate contact is etched, and aluminum is deposited, patterned, and alloyed. This technology development is aimed at incorporating three large-format infrared detecting arrays based on GaAs QWIP technology onto a common focal plane with precision alignment of all three arrays. This focal plane must survive the rigors of flight qualification and operate at a temperature of 43 K (-230 C) for five years while orbiting the Earth. The challenges presented include ensuring thermal compatibility among all the components, designing and building a compact, somewhat modular system and ensuring alignment to very tight levels. The multi-array focal plane integrated onto a single silicon substrate is a new application of both QWIP array development and silicon wafer scale integration. The Invar-based assembly has been tested to ensure thermal reliability.

  5. Fast decoding of codes from algebraic plane curves

    DEFF Research Database (Denmark)

    Justesen, Jørn; Larsen, Knud J.; Jensen, Helge Elbrønd;

    1992-01-01

    Improvement to an earlier decoding algorithm for codes from algebraic geometry is presented. For codes from an arbitrary regular plane curve the authors correct up to d*/2-m2 /8+m/4-9/8 errors, where d* is the designed distance of the code and m is the degree of the curve. The complexity of finding...

  6. Size-effects in plane strain sheet-necking

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Redanz, Pia

    2003-01-01

    A finite strain generalization of the strain gradient plasticity theory by Fleck and Hutchinson (2001) is proposed and used to study size effects in plane strain necking of thin sheets using the finite element method. Both sheets with rigid grips at the ends and specimens with shear free ends are...

  7. Scan-plane truncation in diffraction tomography-based imaging

    DEFF Research Database (Denmark)

    Rubæk, Tonny; Meincke, Peter

    2005-01-01

    Three approaches for truncating the scan plane in diffraction tomography-based imaging are suggested and compared. The first and second approaches involve multiplication of a window to the scattered field before evaluating the spatial Fourier transform. The third method relies on an asymptotic end...

  8. Motion on an Inclined Plane and the Nature of Science

    Science.gov (United States)

    Pendrill, Ann-Marie; Ekström, Peter; Hansson, Lena; Mars, Patrik; Ouattara, Lassana; Ryan, Ulrika

    2014-01-01

    Friction is an important phenomenon in everyday life. All children are familiar with playground slides, which may thus be a good starting point for investigating friction. Motion on an inclined plane is a standard physics example. This paper presents an investigation of friction by a group of 11-year olds. How did they plan their investigations?…

  9. Making Robot Planes Useful for Scientific Investigation of Earth

    Science.gov (United States)

    Jennison, Chris

    2006-01-01

    This viewgraph slides presentation reviews the program to use unmanned aerial vehicles to gather information to study the Earth, the changes to the climate, and to protect the Earth. Several robot planes are shown, and cooperative programs with other agencies of the U.S. Government are highlighted. Including one with the United States Forest Service, that is planned to assist in locating fires

  10. Simulation of cohesive fine powders under a plane shear

    NARCIS (Netherlands)

    Takada, Satohsi; Saitoh, K.; Hayakawa, H.

    2014-01-01

    Three-dimensional molecular-dynamics simulations of cohesive dissipative powders under a plane shear are performed. We find the various phases depending on the dimensionless shear rate and the dissipation rate as well as the density. We also find that the shape of clusters depends on the initial con

  11. Projecting diffusion along the normal bundle of a plane curve

    International Nuclear Information System (INIS)

    The purpose of this paper is to provide new formulas for the effective diffusion coefficient of a generalized Fick-Jacob's equation obtained by projecting the two-dimensional diffusion equation along the normal directions of an arbitrary curve on the plane

  12. Planes of satellite galaxies: when exceptions are the rule

    CERN Document Server

    Cautun, Marius; Frenk, Carlos S; Guo, Qi; Han, Jiaxin; Hellwing, Wojciech A; Sawala, Till; Wang, Wenting

    2015-01-01

    The detection of planar structures within the satellite systems of both the Milky Way (MW) and Andromeda (M31) has been reported as being in stark contradiction to the predictions of the standard cosmological model ($\\Lambda$CDM). Given the ambiguity in defining a planar configuration, it is unclear how to interpret the low incidence of the MW and M31 planes in $\\Lambda$CDM. We investigate the prevalence of satellite planes around galactic mass haloes identified in high resolution cosmological simulations. We find that planar structures are very common, and that ~10% of $\\Lambda$CDM haloes have even more prominent planes than those present in the Local Group. While ubiquitous, the planes of satellite galaxies show a large diversity in their properties. This precludes using one or two systems as small scale probes of cosmology, since a large sample of satellite systems is needed to obtain a good measure of the object-to-object variation. This very diversity has been misinterpreted as a discrepancy between the ...

  13. Tilings of the plane: Thurston semi-norm and decidability

    CERN Document Server

    Chazottes, J -R; Gautero, F

    2012-01-01

    We give a geometric interpretation of the undecidability of the tiling problem in the plane. We show that this problem boils down to prove the existence of zeros of a nonnegative convex function defined on a finite-dimensional simplex and related to the Thurston semi-norm.

  14. DNS and RANS modelling of a turbulent plane impinging jet

    NARCIS (Netherlands)

    Jaramillo, J. E.; Trias, F. X.; Gorobets, A.; Perez-Segarra, C. D.; Oliva, A.

    2012-01-01

    The main objective of this paper is to study in detail the fluid flow and the heat transfer in plane impinging jets. Mean and fluctuating velocities and global parameters, i.e. the local Nusselt number, are analysed. The study is focused on a Reynolds number 20,000 (based on the bulk inlet velocity

  15. Projecting diffusion along the normal bundle of a plane curve

    Energy Technology Data Exchange (ETDEWEB)

    Valero-Valdés, Carlos [Departamento de Matemáticas Aplicadas y Sistemas, Universidad Autónoma Metropolitana-Cuajimalpa, México, D.F 4871, México (Mexico); Herrera-Guzmán, Rafael [Centro de Investigación en Matemáticas (CIMAT), Guanajuato, Gto, México (Mexico)

    2014-05-15

    The purpose of this paper is to provide new formulas for the effective diffusion coefficient of a generalized Fick-Jacob's equation obtained by projecting the two-dimensional diffusion equation along the normal directions of an arbitrary curve on the plane.

  16. A Geometric Interpretation of Half-Plane Capacity

    CERN Document Server

    Lalley, Steven; Narayanan, Hariharan

    2009-01-01

    Let $A$ be a bounded, relatively closed subset of the upper half plane $\\mathbb{H}$ whose complement in $\\mathbb{H}$ is simply connected. If $B_t$ is a standard complex Brownian motion and $\\tau_A = \\inf\\{t \\geq 0: B_t \

  17. Integral representation in the hodograph plane of compressible flow

    DEFF Research Database (Denmark)

    Hansen, Erik Bent; Hsiao, G.C.

    2003-01-01

    Compressible flow is considered in the hodograph plane. The linearity of the equation determining the stream function is exploited to derive a representation formula involving boundary data only, and a fundamental solution to the adjoint equation. For subsonic flow, an efficient algorithm for...

  18. Dense Focal Plane Arrays for Pushbroom Satellite Radiometers

    DEFF Research Database (Denmark)

    Iupikov, O. A.; Ivashina, M. V.; Pontoppidan, K.;

    2014-01-01

    Performance of a dense focal plane array feeding an offset toroidal reflector antenna system is studied and discussed in the context of a potential application in multi-beam radiometers for ocean surveillance. We present a preliminary design of the array feed for the 5-m diameter antenna at X...

  19. Zero-mass plane waves in nonzero gravitational backgrounds

    International Nuclear Information System (INIS)

    The mathematical definition of what is intuitively called a ''plane wave'' on the curved background of a black hole is clarified and discussed from the viewpoints of potentials and fields. Because of the long-range Newtonian part of the gravitational field the asymptotic wave fronts of an incident ''plane wave'' (describing a radiative perturbation for a scattering experiment) are distorted in a manner analogous to the wave fronts of an electron beam in the quantum-mechanical Coulomb scattering problem. In addition, the electromagnetic and gravitational fields can be described with either a potential formalism (i.e., the vector potential and the metric perturbation) or a field formalism (i.e., the electromagnetic field tensor and the Riemann tensor). In this paper we present a distorted ''plane wave'' prescription, necessary for the calculation of the scattering cross sections of electromagnetic and gravitational waves off of a black hole, which agrees with the accepted prescription for a massless scalar field and satisfies the intuitive notions of what constitutes a ''plane wave'' in terms of potentials and fields

  20. Colliding plane waves in N-italic = 1 classical supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Rosenbaum, M.; Ryan, M.; Urrutia, L.F.; Matzner, R.A.

    1986-07-15

    An exact solution is presented for colliding plane waves in N-italic = 1 classical supergravity. Contrary to the situation in ordinary gravity, this solution is nonsingular everywhere. The Grassmann algebra is shown to be responsible for the vanishing of terms in the Raychaudhuri equation that generate the singularity in the pure gravity case.