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Sample records for cenomanian cardiel formation

  1. The Cretaceous (Cenomanian) continental record of the Laje do Coringa flagstone (Alcântara Formation), northeastern South America

    Medeiros, Manuel Alfredo; Lindoso, Rafael Matos; Mendes, Ighor Dienes; Carvalho, Ismar de Souza

    2014-08-01

    The fossil taxa of the Cenomanian continental flora and fauna of São Luís Basin are observed primarily in the bone bed of the Laje do Coringa, Alcântara Formation. Many of the disarticulated fish and tetrapod skeletal and dental elements are remarkably similar to the chronocorrelate fauna of Northern Africa. In this study, we present a summary of the continental flora and fauna of the Laje do Coringa bone-bed. The record emphasizes the existence of a trans-oceanic typical fauna, at least until the early Cenomanian, which may be interpreted as minor evolutionary changes after a major vicariant event or as a result of a land bridge across the equatorial Atlantic Ocean, thereby allowing interchanges between South America and Africa. The paleoenvironmental conditions in the northern Maranhão State coast during that time were inferred as forested humid areas surrounded by an arid to semi-arid landscape.

  2. Spatial and Temporal Variations of the Indidura Formation (Cenomanian-Turonian) in Northeastern Mexico, Coahuila State

    Duque-Botero, F.; Maurrasse, F. J.

    2002-12-01

    Rock sequences of Cenomanian-Turonian age commonly assigned to the Indidura Formation in northeastern Mexico, Coahuila State, are shown to include distinct facies indicative of significant spatial variability over the carbonate platform of that region. The type section at Las Delicias is characterized by very-pale orange (10YR8/2) bedded biocalcirudites (10-30 cm thick), without internal structures, and comprises fossil assemblages rich in epifaunal groups, as well as nektonic and planktic taxa. Total inorganic carbon (TIC) varies between 48 % and 94 %, with fluctuation in total organic carbon (TOC) between 0.73 % and 1.58 %. The section at la Casita Canyon, farther southeast, consists of pale yellowish brown (10YR6/2) interbedded biocalcilutites and olive gray (5Y3/2) shales between 3 and 30 cm thick. They also show no apparent original internal structures, and allochems consist essentially of sparse fragments of planktonic foraminifera and radiolarian. TIC content varies between 0.84 % and 59.3 %, whereas TOC changes between 0.17 % and 5.85 %. In contrast, in the Parras Mountains, located south of La Delicias and northwest of la Casita, the succession occurs under a characteristic sequence showing interbeds of light olive gray (5Y6/1) and brownish black to olive black (5YR2/1 - 5Y2/1) shales and marly biocalcilutites 30 to 100 cm thick. They display distinct internal structures arranged in nearly even parallel varve-like dual lamina (TIC content varies from 43 % to 78.3 %, while TOC content remains relatively high with values between 7.35 % and 24.39 %, but more consistently higher than 20 %. Assuming that these facies are coeval, microfacies studies of these rocks as well as acid etched polished rocks, and scanning electron microscope examination (secondary and backscatter imaging) further substantiate these spatial differences. TOC-rich black shales in the Parras region further document unique paleoceanographic conditions, which was also characterized by

  3. Organic Geochemistry of the Cenomanian-Turonian Bahloul Formation Petroleum Source Rock, Central and Northern Tunisia

    Affouri , Hassene; Montacer , Mabrouk; Disnar , Jean-Robert

    2013-01-01

    International audience; Total organic carbon (TOC) determination, Rock-Eval pyrolysis, extractable organic matter content (EOM) fractionation, gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyses, were carried out on 79 samples from eleven outcrop cross sections of the Bahloul Formation in central and northern Tunisia. The TOC content varied between 0.23 to 35.6%, the highest average values (18.73%, 8.46% and 4.02%) being at the east of the study area (at Ain Zakk...

  4. Upper cretaceous ammonite succession (Cenomanian - Coniacian) related to the upper Hondita and Loma Gorda Formations along the Bambuca creek, Aipe, Huila (Colombia, S.A.)

    Patarroyo, Pedro

    2011-01-01

    The Bambuca creek section (Aipe - Huila) shows a very good exposition of the upper Magdalena valley cretaceous deposits. To the upper part of the Hondita Formation were recollected acanthoceras sp. and rhynchostreon sp. of the upper Cenomanian. Related to the lower segment of the Loma Gorda Formation were found choffaticeras (c.) cf. segne, fagesia cf. catinus, neoptychites cf. andinus, mitonia gracilis, morrowitessp., nannovascoceras ? sp., quitmaniceras ? sp., benueites ? sp., paramammites ? sp. together with mytiloideskossmati, m. goppelnensis and anomia sp. of the lower Turonian. Following by hoplitoides sp. h. ingens,h. cf. lagiraldae, codazziceras ospinae, allocrioceras sp. that can be representing between the lower and middle Turonian. To the upper part of this segment were collected prionocycloceras sp. p. guayabanum, reesidites subtuberculatum, subprionotropis colombianus, mytiloides scupini, dydimotis sp., gauthiericerassp, anagaudryceras ? sp., eulophoceras jacobi, paralenticeras sieversi, hauericeras cf. madagascarensis, peroniceras (p.) subtricarinatum, forresteria (f.) sp, barroisiceras cf. onilahyense, ankinatsytes venezolanus, with upper Turonian to Coniacian. According to the related fauna it is not possible to establish the Cenomanian/Turonian and Turonian/Coniacian boundaries.

  5. Influence of a major exposure surface on the development of microporous micritic limestones - Example of the Upper Mishrif Formation (Cenomanian) of the Middle East

    Deville de Periere, M.; Durlet, C.; Vennin, E.; Caline, B.; Boichard, R.; Meyer, A.

    2017-05-01

    Microporous platform top limestones of the Cenomanian Mishrif Formation (offshore Qatar) were studied in order to investigate the diagenetic processes associated with the top-Mishrif subaerial unconformity and its influence on the development of microporosity in underlying carbonates. Petrographical and stable isotope results indicate that complex diagenetic changes occurred during subaerial exposure of the Mishrif Formation, including pervasive dissolution and meteoric cementation, as well as neomorphism of the micritic matrix. Micrites at the top of the Mishrif Formation are coarse (i.e. > 2 μm), sub-rounded and very dull luminescent under cathodoluminescence. In this uppermost part of the studied interval, the limestone matrix first underwent dissolution of unstable grains in the vadose zone, with subsequent precipitation of low-magnesium calcite (LMC) overgrowths within an oxidising phreatic setting. This process explains the poor luminescence of the micrite crystals and their relatively coarse crystallometry which results in the present day in relatively good reservoir properties. δ13C ratios within the microporous limestones are negative (up to - 4‰ V-PDB) due to the incorporation of isotopically light carbon derived from palaeosols which developed during exposure. By contrast, fine (i.e. aquifer associated with the Top-Mishrif Unconformity, and were precipitated from meteoric or mixed dysoxic waters which were slightly supersaturated with respect to calcite.

  6. Continental fossil vertebrates from the mid-Cretaceous (Albian-Cenomanian) Alcântara Formation, Brazil, and their relationship with contemporaneous faunas from North Africa

    Candeiro, Carlos Roberto A.; Fanti, Federico; Therrien, François; Lamanna, Matthew C.

    2011-05-01

    The Albian-Cenomanian Alcântara Formation of northeastern Brazil preserves the most diverse continental vertebrate fauna of this age yet known from northern South America. The Alcântara vertebrate assemblage, consisting of elasmobranchs, actinopterygians, sarcopterygians, turtles, crocodyliforms, pterosaurs, and non-avian dinosaurs, displays close similarities to contemporaneous faunas from North Africa. The co-occurrence of as many as eight freshwater or estuarine fish taxa ( Onchopristis, Bartschichthys, Lepidotes, Stephanodus, Mawsonia, Arganodus, Ceratodus africanus, and possibly Ceratodus humei) and up to seven terrestrial archosaur taxa ( Sigilmassasaurus, Rebbachisauridae, Baryonychinae, Spinosaurinae, Carcharodontosauridae, possibly Pholidosauridae, and doubtfully Bahariasaurus) suggests that a land route connecting northeastern Brazil and North Africa existed at least until the Albian. Interestingly, most components of this mid-Cretaceous northern South American/North African assemblage are not shared with coeval southern South American faunas, which are themselves characterized by a number of distinct freshwater and terrestrial vertebrate taxa (e.g., chelid turtles, megaraptoran and unenlagiine theropods). These results suggest that, although mid-Cretaceous faunal interchange was probably possible between northern South America and North Africa, paleogeographic, paleoclimatic, and/or paleoenvironmental barriers may have hindered continental vertebrate dispersal between northern and southern South America during this time.

  7. Evidence of synsedimentary microbial activity and iron deposition in ferruginous crusts of the Late Cenomanian Utrillas Formation (Iberian Basin, central Spain)

    García-Hidalgo, José F.; Elorza, Javier; Gil-Gil, Javier; Herrero, José M.; Segura, Manuel

    2018-02-01

    Ferruginous sandstones and crusts are prominent sedimentary features throughout the continental (braided)-coastal siliciclastic (estuarine-tidal) wedges of the Late Cenomanian Utrillas Formation in the Iberian Basin. Crust types recognized are: Ferruginous sandy crusts (Fsc) with oxides-oxyhydroxides (hematite and goethite) concentrated on sandstone tops presenting a fibro-radial internal structure reminding organic structures that penetrate different mineral phases, suggesting the existence of bacterial activity in crust development; Ferruginous muddy crusts (Fmc) consisting of wavy, laminated, microbial mats, being composed mainly of hematite. On the other hand, a more dispersed and broader mineralization included as Ferruginous sandstones with iron oxides and oxyhydroxides (hematite and goethite) representing a limited cement phase on these sediments. The presence of microbial remains, ferruginous minerals, Microbially-induced sedimentary structures, microbial laminites and vertebrate tracks preserved due to the presence of biofilms suggest firstly a direct evidence of syn-depositional microbial activity in these sediments; and, secondly, that iron accumulation and ferruginous crusts development occurred immediately after deposition of the host, still soft sediments. Ferruginous crusts cap sedimentary cycles and they represent the gradual development of hard substrate conditions, and the development of a discontinuity surface at the top of the parasequence sets, related to very low sedimentary rates; the overlying sediments record subsequent flooding of underlying shallower environments; crusts are, consequently, interpreted as boundaries for these higher-order cycles in the Iberian Basin.

  8. Foraminiferal and radiolarian biostratigraphy of the youngest (Late Albian through Late Cenomanian) sediments of the Tatra massif, Central Western Carpathians

    Bąk, Krzysztof; Bąk, Marta

    2013-06-01

    Bąk, K. and Bąk M. 2013. Foraminiferal and radiolarian biostratigraphy of the youngest (Late Albian through Late Cenomanian) sediments of the Tatra massif, Central Western Carpathians. Acta Geologica Polonica, 63 (2), 223-237. Warszawa. The foraminiferal and radiolarian biostratigraphy of selected sections of the Zabijak Formation, the youngest sediments of the Tatra massif (Central Western Carpathians), have been studied. Benthic foraminifers, mainly agglutinated species, occur abundantly and continuously throughout the studied succession, while planktic foraminifers are generally sparse. Five planktic and two benthic foraminiferal zones have been recognized. The marly part of the Zabijak Formation comprises the Pseudothalmanninella ticinensis (Upper Albian) through the Rotalipora cushmani (Upper Cenomanian) planktic foraminiferal zones, and the Haplophragmoides nonioninoides and Bulbobaculites problematicus benthic foraminiferal zones. The radiolarians were recognized exclusively in the Lower Cenomanian part of the formation.

  9. Cenomanian-? early Turonian minimum age of the Chubut Group, Argentina: SHRIMP U-Pb geochronology

    Suárez, Manuel; Márquez, Marcelo; De La Cruz, Rita; Navarrete, César; Fanning, Mark

    2014-03-01

    Four new SHRIMP U-Pb zircon ages older than 93 Ma from samples of the two uppermost formations accumulated in two different depocenters (Golfo de San Jorge and Cañadón Asfalto basins) of the Chubut Group in central Argentinean Patagonia, establish a pre-late Cenomanian-? early Turonian age for the group. It also confirms a coeval and comparable evolution of the two depocenters, where distal pyroclastic material was deposited together with fluvial and lacustrine facies.

  10. An enigmatic aquatic snake from the Cenomanian of Northern South America

    Adriana Albino

    2016-05-01

    Full Text Available We report the first record of a snake from the Cretaceous of northern South America. The remains come from the La Luna Formation (La Aguada Member, Cenomanian of Venezuela and consist of several vertebrae, which belong to the precloacal region of the vertebral column. Comparisons to extant and extinct snakes show that the remains represent a new taxon, Lunaophis aquaticus gen. et sp nov. An aquatic mode of life is supported by the ventral position of the ribs, indicating a laterally compressed body. The systematic relationships of this new taxon are difficult to determine due to the scarcity of fossil material; it is, however, a representative of an early lineage of snakes that exploited tropical marine pelagic environments, as reflected by the depositional conditions of the La Aguada Member. Lunaophis is also the first aquatic snake from the Cenomanian found outside of the African and European Tethyan and Boreal Zones.

  11. Changes in carbonate sedimentation and faunal assemblages in the Tunisian carbonate platform around the Cenomanian-Turonian boundary

    Touir, Jamel; Mechi, Chefia; Haj Ali, Hajer

    2017-05-01

    In Tunisia the Cenomanian-Turonian boundary coincides with the transition between two carbonate deposits: the Late Cenomanian Bahloul Formation at the bottom and the Early Turonian Gattar Member at the top. According to field study and microscope examination of the studied Formations throughout Tunisia, the Bahloul Formation consists of a deep-water condensed carbonate platform largely extended throughout Tunisia. Detailed analysis shows a particular richness in planktonic microfauna and ammonites. Thin bedded limestones within the Upper part exhibits a high TOC ratio and commonly called the black shales, whereas the Gattar Member displayed a rudist-bearing carbonate ramp which pinches northward while being progressively relayed by hemipelagic marls forming the so-called Annaba Member. The Cenomanian-Turonian transition was marked by relevant changes the main features of which are well recorded in the Tunisian carbonate platform. The changes consist of consecutive (i) shutdown and recovery of the carbonate factory and (ii) extinction, development and diversification of many faunal species. As matter of fact, during Late Cenomanian many planktonic foraminifers (Rotaliporidae) and rudists (Caprinidae) were extinct, and simultaneously the carbonate production rate fallen into 0.003-0.017 m k y -1. During Early Turonian the carbonate platform recovered contemporaneously with the development and diversification of many planktonic foraminifera and rudists (Hippuritidae); the carbonate productivity rose to 0.125 m k y -1 in average. The whole previous changes are to be linked with the significant sea-level fluctuation and the contemporaneous oceanic anoxic event (OAE2) having occurred at the Cenomanian-Turonian boundary.

  12. Lower and Middle Cenomanian ammonites from the Morondava Basin, Madagascar

    Kennedy, William James; Walaszczyk, Ireneusz; Gale, Andrew S.; Dembicz, Krzysztof; Praszkier, Tomasz

    2013-12-01

    Kennedy, W.J., Walaszczyk, I., Gale, A.S., Dembicz, K. and Praszkier, T. 2013. Lower and Midle Cenomanian ammonites from the Morondava Basin, Madagascar. Acta Geologica Polonica, 63(4), 625-655. Warszawa. Lower and Middle Cenomanian ammonite assemblages have been collected on a bed-by-bed basis from localities at Vohipaly and Mahaboboka, Madagascar, as well as from outcrops around Berekata, all in the Morondava Basin, southwest Madagascar. These collections demonstrate the presence of the upper Lower Cenomanian Mantelliceras dixoni Zone and the lower Middle Cenomanian Cunningtoniceras inerme Zone of the north-western European standard sequence. These records indicate that the striking anomalies in the zonal assemblages of the classic divisions of the Madagascan Cenomanian are based on mixed assemblages, rather than a succession that differs radically from that elsewhere in the world. The dixoni Zone fauna is: Desmoceras cf. latidorsatum (Michelin, 1838), Pachydesmoceras kossmati Matsumoto, 1987, Forbesiceras sp., F. baylissiWright & Kennedy, 1984, F. largilliertianum (d'Orbigny, 1841), Mantelliceras cantianum Spath, 1926a, M. dixoni Spath, 1926b, M. mantelli (J. Sowerby, 1814), M. picteti Hyatt, 1903, M. saxbii (Sharpe, 1857), Sharpeiceras sp., S. falloti (Collignon, 1931), S. mocambiquense (Choffat, 1903), S. cf. florencae Spath, 1925, Acompsoceras renevieri (Sharpe, 1857), A. tenue Collignon, 1964, Calycoceras sp., Mrhiliceras lapparenti (Pervinquière, 1907), Mariella (Mariella) stolizcai (Collignon, 1964), Hypoturrilites taxyfabreae (Collignon, 1964), Turrilites scheuchzerianus Bosc, 1801, Sciponoceras cucullatum Collignon, 1964, and Sciponoceras antanimangaensis (Collignon, 1964). The presence of Calycoceras in a Lower Cenomanian association represents a precocious appearance of a genus typically Middle and Upper Cenomanian in occurrence, and matches records from Tunisia. The inerme Zone yields a more restricted assemblage: Pachydesmoceras kossmati

  13. New Ichnospecies of Scratching Traces from Phosphatic nodules (Cenomanian, England)

    Chumakov, N. M.; Dronov, A. V.; Mikuláš, Radek

    2013-01-01

    Roč. 21, č. 3 (2013), s. 50-59 ISSN 0869-5938 Institutional research plan: CEZ:AV0Z30130516 Institutional support: RVO:67985831 Keywords : trace fossils * Cenomanian * southern England * systems of scratches * biting traces * bioerosion * homodont * heterodont Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.714, year: 2013

  14. NEW ABELISAURID MATERIAL FROM THE UPPER CRETACEOUS (CENOMANIAN OF MOROCCO

    SIMONE D'ORAZI PORCHETTI

    2011-11-01

    Full Text Available Fragmentary cranial bones of dinosaur origin have been recently recovered from the Kem Kem beds (Upper Cretaceous, Cenomanian of Morocco. They include two incompletely preserved maxillary bones evidencing diagnostic features of abelisaurid theropods. These new finds provide further evidence of Abelisauridae in the Late Cretaceous of Morocco. 

  15. Cenomanian and Cenomanian-Turonian boundary deposits in the southern part of the Bohemian Cretaceous Basin, Czech Republic

    Čech, S.; Hradecká, L.; Svobodová, Marcela; Švábenická, L.

    2005-01-01

    Roč. 80, č. 4 (2005), s. 321-354 ISSN 1210-3527 Grant - others:GA MŽP1(CZ) 1975/630/02 Institutional research plan: CEZ:AV0Z3013912 Keywords : Cenomanian * biostratigraphy * Bohemian Cretaceous Basin Subject RIV: DB - Geology ; Mineralogy http://www.geology.cz/bulletin/contents/2005/vol80no4/321_cech.pdf

  16. Global Paleobathymetry for the Cenomanian-Turonian (90 Ma)

    Goswami, A.; Olson, P.; Hinnov, L. A.; Gnanadesikan, A.

    2014-12-01

    We present a paleo-ocean bathymetry reconstruction for Cenomanian-Turonian (90 Ma) time in a 0.1°x0.1° resolution for use in paleo-climate studies. Age of the ocean floor for the Cenomanian-Turonian (90 Ma) is from Müller et al. (2008 a,b); coastlines are from the PALEOMAP Project (Scotese, 2011). To reconstruct paleo-ocean bathymetry, we use a plate model equation to model depth to basement (Turcotte and Schubert, 2002). We estimate plate model equation parameter values from measurements of modern oceans (Crosby et al., 2006). On top of the depth to basement, we isostatically add a multilayer sediment model derived from area-corrected sediment thickness data (Divins, 2003; Whittaker et al., 2013). Lastly, we parameterize the modern continental shelf, slope, and rise in a "sediment wedge model" to connect the coastline with the closest ocean crust as defined by Müller et al. (2008 a, b). These parameters are defined using empirical relationships obtained from study of modern ocean transects where a complete rifting history is preserved (Atlantic and Southern oceans), and the closest approach of the respective oceanic crust (Müller et al., 2008a,b) to the coastline. We use the modern ocean as a test, comparing maps and cross sections of modern ocean bathymetry modeled using our reconstruction method with that of ETOPO1 (Amante and Eakins, 2009). Adding sea plateaus and seamounts minimize the difference between our modeled bathymetry and ETOPO1. Finally, we also present a comparison of our reconstructed paleo-bathymetry to that of Müller et al. (2008 a,b) for the Cenomanian-Turonian (90 Ma). References: Amante, C., Eakins, B.W., 2009, NOAA Tech. Memo. NESDIS NGDC-24, 19 p. Crosby, A., McKenzie, D., Sclater, J.G., 2006, Geophysical Journal Int. 166.2, 553-573. Divins, D., 2003, NOAA NGDC, Boulder, CO. Müller, R., Sdrolias, M., Gaina, C., Roest, W., 2008b, Geochemistry, Geophysics, Geosystems, 9, Q04006, doi:10.1029/2007GC001743 Müller, R., Sdrolias, M., Gaina

  17. Late Cenomanian - Early Turonian Hardgrounds and nearshore Depositional Environments (Bohemian Cretaceous Basin)

    Žítt, Jiří; Bosák, Pavel; Hradecká, L.; Svobodová, Marcela

    Colloque sur le Cénomanien/Colloquium on the Cenomanian Stage, - (2001), s. 105-107 ISSN 0766-5946. [Colloque sur le Cénomanien/Colloquium on the Cenomanian Stage. Rouen, 20.10.2001-21.10.2001] R&D Projects: GA ČR GA205/99/1315 Institutional research plan: CEZ:AV0Z3013912 Keywords : Upper Cretaceous * Hardgrounds Subject RIV: DB - Geology ; Mineralogy

  18. Elemental geochemistry and strontium-isotope stratigraphy of Cenomanian to Santonian neritic carbonates in the Zagros Basin, Iran

    Navidtalab, Amin; Rahimpour-Bonab, Hossain; Huck, Stefan; Heimhofer, Ulrich

    2016-12-01

    A Neo-Tethyan upper Cenomanian-Santonian neritic carbonate ramp succession (Sarvak and Ilam formations), drilled in the Zagros Basin in southwest Iran, was investigated via detailed sedimentology, microfacies analysis, elemental geochemistry and Sr-isotope stratigraphy (SIS). The succession contains two exposure surfaces, which are known as the CT-ES and mT-ES (Cenomanian-Turonian and middle Turonian, respectively), and associated prominent negative carbon-isotope excursions that represent important regional stratigraphic marker horizons. Precise knowledge about the onset of platform exposure and the duration of the exposure-related hiatus, however, is currently lacking due to a rather low-resolved shallow-water biostratigraphic framework and a bulk carbonate carbon-isotope pattern that clearly differs from global Late Cretaceous reference curves. Therefore, the existing bio-chemostratigraphic framework was complemented by bulk carbonate strontium-isotope stratigraphy (SIS). As bulk carbonate material is in particular prone to diagenetic alteration, a careful selection of least altered samples has been carried out by means of elemental geochemistry and petrography. In contrast to what could be expected, the meteoric alteration of limestones beneath both exposure surfaces is not clearly expressed by increasing iron and manganese and coeval decreasing strontium contents. On the contrary, the impact of meteoric diagenesis is well illustrated via pronounced increases in Rb concentrations and concomitant prominent positive shifts to radiogenic strontium-isotope values, an observation that clearly reflects the decay of continentally derived 87Rb into 87Sr. Rubidium corrected strontium-isotope values place the CT-ES around the Cenomanian-Turonian boundary and point to an exposure duration of less than 0.4 Myr. This rather short-term CT-ES related hiatus is supported by petrographic evidence, which indicates a youth karstification stage of strata beneath the CT

  19. Cenomanian-Turanian anoxic event and potential petroleum source rocks of the Upper Benue Trough, Nigeria

    Mohammed, B.

    2004-01-01

    Foraminiferal palaeoenviromental studies particularly planktonic/benthonic (p/b) ratio have been used to demarcate anoxic horizon within the Cenomanian-Turonian sequence of the Upper Benue trough. The foraminiferal faunal assemblages indicate a deep marine .anoxic I sequences. Geochemical analysis of organic matter yielded TOC values that are generally fair to moderate with average of 0.70,2.05 and 0.44% in Dukkul, Pindiga and Gongila Formations respectively. Hydrogen indices also indicate preponderance of gas -prone terrestrial type III organic matter. This seems to be inconsistent with anoxic/dysoxic environments in which organic matter is generally expected to be commonly more abundant, better preserved and more lipid rich. Therefore, it is suggested here that such a relatively deep marine anoxic environment was subsequently raised tectonically to very shallow levels (raised oxygen-minimum zone) where terrestrial organic matter were washed into the anoxic water. These terrestrial contributions diluted and downgraded the anoxic level such that TOCs are generally low to moderate and organic matter became generally of type III and IV

  20. On variation in Schloenbachia varians (J. Sowerby, 1817) from the Lower Cenomanian of western Kazakhstan

    Kennedy, William James

    2013-12-01

    Kennedy, W.J. 2013. On variation in Schloenbachia varians (J. Sowerby, 1817) from the Lower Cenomanian of western Kazakhstan Acta Geologica Polonica, 63(4), 443-468. Warszawa. An assemblage of 94 specimens of Schloenbachia varians (J. Sowerby, 1817) from the Lower Cenomanian Sharpeiceras schlueteri Subzone of the Mantelliceras mantelli Zone of the Besakty section in the Mangyshlak Mountains of western Kazakhstan includes 26 complete adults that range from to 59-174 mm in diameter. No size-related dimorphism was detected in the assemblage, which shows wide, continuous intraspecific variation. This is described in terms of five formae; from robust to gracile these are: ventriosa, varians sensu stricto, subtuberculata , intermedia, and subplana. The ratio of robust (ventriosa + varians sensu stricto) to gracile (subtuberculata + intermedia + subplana) individuals is 34% to 66%. The reference specimens of the formae and their synonyms are described and illustrated, and related to the Besakty material. The modification of adult body chamber ornament of all formae is documented, and Jakeiceras Cooper and Owen, 2011 is shown to be based on an adult of a passage form between forma subtuberculata and forma intermedia. The differences between Lower Cenomanian S. varians, lower Middle Cenomanian S. coupei (Brongniart, 1822), and upper Middle and lower Upper Cenomanian S. lymensis Spath, 1926b are described and illustrated.

  1. Sequence stratigraphic analysis of Cenomanian greenhouse palaeosols: A case study from southern Patagonia, Argentina

    Varela, Augusto N.; Veiga, Gonzalo D.; Poiré, Daniel G.

    2012-10-01

    The aim of this contribution is to analyse extrinsic (i.e., tectonics, climate and eustasy) and intrinsic (i.e., palaeotopography, palaeodrainage and relative sedimentation rates) factors that controlled palaeosol development in the Cenomanian Mata Amarilla Formation (Austral foreland basin, southwestern Patagonia, Argentina). Detailed sedimentological logs, facies analysis, pedofeatures and palaeosol horizon identification led to the definition of six pedotypes, which represent Histosols, acid sulphate Histosols, Vertisols, hydromorphic Vertisols, Inceptisols and vertic Alfisols. Small- and large-scale changes in palaeosol development were recognised throughout the units. Small-scale or high-frequency variations, identified within the middle section are represented by the lateral and vertical superimposition of Inceptisols, Vertisols and hydromorphic Vertisols. Lateral changes are interpreted as the result of intrinsic factors to the depositional systems, such as the relative position within the floodplain and the distance from the main channels, that condition the nature of parent material, the sedimentation rate and eventually the palaeotopographic position. Vertical stacking of different soil types is linked to avulsion processes and the relatively abrupt change in the distance to main channels as the system aggraded. The large-scale or low-frequency vertical variations in palaeosol type occurring in the Mata Amarilla Formation are related to long-term changes in depositional environments. The lower and upper sections of the studied logs are characterised by Histosols and acid sulphate Histosols, and few hydromorphic Vertisols associated with low-gradient coastal environments (i.e., lagoons, estuaries and distal fluvial systems). At the lower boundary of the middle section, a thick palaeosol succession composed of vertic Alfisols occurs. The rest of the middle section is characterised by Vertisols, hydromorphic Vertisols and Inceptisols occurring on distal and

  2. Cenomanian-Turonian aquifer of central Israel, its development and possible use as a storage reservoir

    Schneider, Robert

    1964-01-01

    The Cenomanian-Turonian formations constitute a highly permeable dolomite and limestone aquifer in central Israel. The aquifer is on the west limb of an anticlinorium that trends north-northeast. In places it may be as much as 800 meters thick, but in the report area, largely the foothills of the Judean-Ephraim Mountains where the water development is most intensive, its thickness is generally considerably less. In some places the aquifer occurs at or near the land surface, or it is covered by sandy and gravelly coastal-plain deposits. However, in a large part of the area, it is overlain by as much as 400 meters of relatively impermeable strata, and it is probably underlain by less permeable Lower Cretaceous strata. In general the aquifer water is under artesian pressure. The porosity of the aquifer is characterized mainly by solution channels and cavities produced by jointing and faulting. In addition to the generally high permeability of the aquifer, some regions, which probably coincide with ancient drainage patterns and (or) fault zones, have exceptionally high permeabilities. The source of most of the water in the aquifer is believed to be rain that falls on the foothills area. The westward movement of ground water from the mountainous outcrop areas appears to be impeded by a zone of low permeability which is related to structural and stratigraphic conditions along the western side of the mountains. Gradients of the piezometric surface are small, and the net direction of water movement is westward and northwestward under natural conditions. Locally, however, the flow pattern may be in other directions owing to spatial variations in permeability in the aquifer, the location of natural discharge outlets, and the relation of the aquifer to adjacent geologic formations. There probably is also a large vertical component of flow. Pumping has modified the flow pattern by producing several irregularly shaped shallow depressions in the piezometric surface although, to

  3. Parasitic gastropod bioerosion trace fossil on Cenomanian oysters from Le Mans, France and its ichnologic and taphonomic context

    Gérard Breton

    2017-03-01

    Full Text Available We describe and name Loxolenichnus stellatocinctus Breton and Wisshak igen. et isp. nov., a bioerosion trace fossil on an Upper Cenomanian oyster from Le Mans (France. This trace is attributed here to a parasitic gastropod. The characteristics of this ichnospecies are a combination of one or several, vertical or oblique, complete penetrations, and an asymmetrical attachment etching (fixichnion with a diagnostic set of stellate grooves increasingly distinct towards the margin of the trace. By including two former Oichnus ichnospecies, Loxolenichnus halo comb. nov. and Loxolenichnus taddei comb. nov., Oichnus, is now constrained to pure predation traces (praedichnia. The numerous oysters collected from the Marnes à Pycnodonte biauriculata Formation show associated epibionts and encrusters as well as borers and scrapers. Encrusters comprise 24 taxa while bioerosion trace fossils comprise 17 ichnotaxa ranging from very rare (< 0.1% to quite abundant (81%. The taphonomic history leading to an ex-situ condensation of these oysters is complex. Both the Gnathichnus and Entobia ichnofacies are represented on the shellgrounds, presumably alternatingly.

  4. The upper Cenomanian-lower Turonian of the Preafrican Trough (Morocco): Platform configuration and palaeoenvironmental conditions

    Lebedel, V.; Lézin, C.; Andreu, B.; Ettachfini, El M.; Grosheny, D.

    2015-06-01

    A synthetic study was carried out based on sedimentological, palaeontological, geochemical and mineralogical data of the upper Cenomanian-lower Turonian carbonate platform of the Preafrican Trough (eastern Morocco) in order to (1) propose a 3D representation of the platform and constrain the temporal framework of the dysoxic/anoxic episodes recorded during the OAE2, (2) define and discuss the prevailing climate on the platform during this period, and (3) make comparisons with other Cenomanian-Turonian platforms. During the late Cenomanian, both before and during the CCIE (Cenomanian Carbon Isotope Excursion), the platform displayed an east-west polarity. Three third-order sequences of transgression-regression can be defined. Dysoxic conditions were developed in the sediments and the bottom waters of the deepest environment (mid- to outer-ramp setting), in the western part of the platform. Well-oxygenated waters were present in the eastern part of the platform (peritidal zone to mid-ramp environment). The climate was arid before the CCIE, becoming warm with contrasted seasons during the CCIE. This climate is associated with a low palaeoproductivity over the entire platform, along with the presence of photozoan followed by heterozoan carbonate-producers, as found also in other parts of the Saharan platform. However, such conditions are not in accordance with many studies which suggest a wet climate during the CCIE, leading to intense chemical weathering of the continent favouring the appearance of high palaeoproductivity at a global scale and the establishment of dysoxic/anoxic conditions. In the Preafrican Trough, poorly-oxygenated waters spread outwards from the deep basins and covered the platform in response to sea-level rise. Many disturbances are recorded in the platform succession during the early Turonian, after the CCIE. Indeed, just after the C/T boundary, the development of an outer-ramp environment over the entire Preafrican Trough reflects flooding of

  5. Upper Cenomanian-lower Turonian sea-level rise and its consequences on the Adriatic-Dinaric carbonate platform

    Gušić, I.; Jelaska, V.

    1993-12-01

    The Adriatic carbonate platform existed throughout most of the Mesozoic as an isolated (‘intraoceanic’) carbonate platform. It is characterized by what has been traditionally labelled a ‘continuous’ shallow marine carbonate sedimentation, without terrigenous influences. However, global sea-level changes left unequivocal imprints in the ‘continuous’ carbonate record, thus proving that the carbonate platform sensitively responded to sea-level fluctuations. This paper focuses on the relatively short Cenomanian — Turonian drowning event, which temporarily submerged the platform below the euphotic zone, and which is related here to the well known global Cenomanian — Turonian sea-level highstand. This drowning episode is characterized by the abrupt disappearance of numerous shallow water benthic invertebrate taxa and by an abundant occurrence of planktonic organisms, including calcispheres and ‘primitive’ planktonic foraminifera. Near the middle of the Turonian, the platform regime was re-established, correlating with the global fall in sea level. The situation is different only at the south-west margin of the platform, where pelagic sedimentation, initiated near the end of the Cenomanian, continues into the Santonian and probably marks the Adriatic trough. The drowning began earlier (in the Middle Cenomanian) in those areas nearer to the north-east margin of the platform (the area of what is today central Croatia) and then progressed gradually towards the more interior areas of the platform (the middle Dalmatian islands), which were drowned near the end of the Cenomanian.

  6. Depositional environment and source rock potential of Cenomanian and Turonian sedimentary rocks of the Tarfaya Basin, Southwest Morocco

    Ghassal, B.I.; Littke, R.; Sachse, V.; Sindern, S.; Schwarzbauer, J.

    2016-07-01

    Detailed organic and inorganic geochemical analyses were used to assess the depositional environment and source rock potential of the Cenomanian and Turonian oil shale deposits in the Tarfaya Basin. This study is based on core samples from the Tarfaya Sondage-4 well that penetrated over 300m of Mid Cretaceous organic matter-rich deposits. A total of 242 samples were analyzed for total organic and inorganic carbon and selected samples for total sulfur and major elements as well as for organic petrology, Rock-Eval pyrolysis, Curie-Point-pyrolysis-gaschromatography-Mass-Spectrometry and molecular geochemistry of solvent extracts. Based on major elements the lower Cenomanian differs from the other intervals by higher silicate and lower carbonate contents. Moreover, the molecular geochemistry suggests anoxic bottom marine water conditions during the Cenomanian-Turonian Boundary Event (CTBE; Oceanic Anoxic Event 2: OAE2). As a proxy for the Sorg/Corg ratio, the ratio total thiophenes/total benzenes compounds was calculated from pyrolysate compositions. The results suggest that Sorg/ Corg is low in the lower Cenomanian, moderate in the upper Cenomanian, very high in the CTBE (CenomanianTuronian Boundary Event) and high in the Turonian samples. Rock-Eval data reveal that the lower Cenomanian is a moderately organic carbon-rich source rock with good potential to generate oil and gas upon thermal maturation. On the other hand, the samples from the upper Cenomanian to Turonian exhibit higher organic carbon content and can be classified as oil-prone source rocks. Based on Tmax data, all rocks are thermally immature. The microscopic investigations suggest dominance of submicroscopic organic matter in all samples and different contents of bituminite and alginite. The lower Cenomanian samples have little visible organic matter and no bituminite. The upper Cenomanian and CTBE samples are poor in bituminite and have rare visible organic matter, whereas the Turonian samples change

  7. Benthic macrofauna variations and community structure in Cenomanian cyclic chalk-marl from Southerham Grey Pit, SE England

    Lauridsen, Bodil Wesenberg; Gale, A. S.; Surlyk, Finn

    2009-01-01

    Cenomanian chalk-marl couplets from England represent the 20 ka Milankovitch precession cycle. Fossil communities from both chalk and marl are identified to test if the orbital fluctuations and the associated changes in substrate lithology and climate exerted any control on the benthic macrofauna...

  8. Palaeoenvironments and facies on a progressively flooded rocky island (Upper Cenomanian – Lower Turonian, Bohemian Cretaceous Basin)

    Žítt, Jiří; Vodrážka, R.; Hradecká, L.; Svobodová, Marcela

    2010-01-01

    Roč. 179, - (2010), s. 223-234 ISSN 1802-6842 Institutional research plan: CEZ:AV0Z30130516 Keywords : Cretaceous island * weathering * geomorphology * sedimentary environments * biostratigraphy * Upper Cenomanian-Lower Turonian * Bohemian Cretaceous Basin Subject RIV: DB - Geology ; Mineralogy http://www.nm.cz/publikace/archiv-en.php?id=1&rok=179&f_=Show

  9. Elemental abundance anomalies in the late Cenomanian extinction interval: a search for the source(s)

    Orth, C.J.; Attrep, M.; Quintana, L.R.; Elder, W.P.; Kauffman, E.G.; Diner, R.; Villamil, T.

    1993-01-01

    Elemental abundances have been measured by neutron activation methods across the Cenomanian-Turonian (late Cretaceous) extinction interval in samples collected from sixteen sites in the Western Interior Basin of North America and from twelve widely separated locations around the globe, including six ODP/DSDP sites. In most Western Interior Basin sites, in Colombia, and in western Europe (weaker), two closely spaced elemental abundance peaks occur in the upper Cenomanian (??? 92 m.y.), spanning the ammonite zones of Sciponoceras gracile through Neocardioceras juddii. Elements with anomalously high concentrations include Sc, Ti, V, Cr, Mn, Co, Ni, Ir, Pt and Au. The lower peak coincides with the disappearance (extinction) of the foraminifer Rotalipora cushmani. In North American sections R. greenhornensis also disappears at or just below this horizon, but in Europe it disappears considerably earlier than R. cushmani. A series of molluscan extinction and speciation or migration events also begins near the stratigraphic level of the lower elemental abundance peak. The well-documented positive ?? 13C excursion begins just before the extinctions and the elemental anomalies, and continues into the lower Turonian, well above the upper anomaly. This carbon isotope excursion has been observed in East European sections where we find little or no evidence of the elemental anomalies, suggesting that the two phenomena may not be tightly coupled. Elemental abundance ratios in the anomalies closely resemble those of Mid-Atlantic Ridge basalt or Hawaiian lava (tholeiitic), but not those of C1 chondrite, black shale, average crustal rocks, or lamproite and kimberlite of roughly similar age in southeastern Kansas. The excess Ir and other siderophiles hint at possible large-body impact(s) for the source. However, we have not located microspherules (other than biogenic calcispheres) or shocked mineral grains in any of our samples. Furthermore, Sc, Ti, V and Mn are not enriched in

  10. MORPHOLOGY, TAXONOMY AND DISTRIBUTION OF THE CRETACEOUS CORAL GENUS PREVERASTRAEA (LATE BARREMIAN-CENOMANIAN; SCLERACTINIA

    HANNES LÖSER

    2007-03-01

    Full Text Available The Cretaceous coral genus Preverastraea is being revised, mainly on the basis of sample material. This cerioid, occasionally astreoid or phaceloid, genus is characterised by round or polygonal calices, compact septa in a regular hexameral symmetry and lonsdaleoid septa. The wall is of the same structure as the septa. The genera Bogdanovicoenia, Paraacanthogyra, and Saxuligyra are considered synonyms of Preverastraea. Related genera are Aulastraeopora and Apoplacophyllia, which only differ by their solitary or dendroid growth forms. There are altogether 13 species of Preverastraea. The genus, which occurred worldwide, is restricted to the period from the Late Barremian to the Late Cenomanian, being most common in the Aptian to Early Albian. Eighty-three samples are either known from the literature or have been to hand. This makes Preverastraea a rather rare genus. 

  11. MORPHOLOGY, TAXONOMY AND DISTRIBUTION OF THE CRETACEOUS CORAL GENUS AULASTRAEOPORA (LATE BARREMIAN-EARLY CENOMANIAN; SCLERACTINIA

    HANNES LÖSER

    2008-03-01

    Full Text Available The Cretaceous coral genus Aulastraeopora is being revised, mainly on the basis of sample material. This genus of solitary growth form is characterised by medium-sized to large specimens, compact septa in a regular hexameral or tetrameral symmetry and lonsdaleoid septa. Related genera are Preverastraea and Apoplacophyllia, which only differ by their cerioid-astreoid and phaceloid growth forms. There are four species of Aulastraeopora. The genus, which occurred world-wide, is restricted to the period from the Late Barremian to the Late Cenomanian, being most common in the Aptian to Early Albian. Forty-one samples are either known from the literature or have been to hand. This makes Aulastraeopora a rare genus. 

  12. A new pachyrhizodontid fish (Actinopterygii, Teleostei from the Muhi Quarry (Albian-Cenomanian, Hidalgo, Mexico

    G. Arratia

    2018-03-01

    Full Text Available A new genus and species – Motlayoichthys sergioi (ZooBank registration: urn:lsid:zoobank.org:pub:2C503741-2362-4234-8CE0-BB7D8BE5A236, urn:lsid:zoobank.org:act:EF5040FD-F306-4C0F-B9DA-2CC696CA349D – from the Cretaceous (Albian-Cenomanian of the Muhi Quarry, Hidalgo, central Mexico is assigned to the family Pachyrhizodontidae based on the presence of the inner premaxillary tooth and a few other cranial characters. Its unique suite of characters, that includes several autapomorphies supports its assignment as a new genus and species, such as the presence of a triangular head with three sides of similar lengths and with its deepest part at the level of the supraoccipital region; the lower jaw projecting anterior to the premaxilla; the ornamentation of cranial bones – especially those of the cheek region – consisting of fine longitudinal crests densely covering the bony surfaces; one or a few deep grooves on the mandibular teeth, which in addition bear acrodin tips ornamented with fine parallel striae; and the position of the dorsal fin, near the posterior margin of the cranium. Motlayoichthys n. gen., together with Michin, Pachyrhizodus, Rhacolepis, and Notelops, is part of the early radiation of pachyrhizodontoids during Albian times.

  13. Assessing global carbon burial during Oceanic Anoxic Event 2, Cenomanian-Turonian boundary event

    Owens, J. D.; Lyons, T. W.; Lowery, C. M.

    2017-12-01

    Reconstructing the areal extent and total amount of organic carbon burial during ancient events remains elusive even for the best documented oceanic anoxic event (OAE) in Earth history, the Cenomanian-Turonian boundary event ( 93.9 Ma), or OAE 2. Reports from 150 OAE 2 localities provide a wide global distribution. However, despite the large number of sections, the majority are found within the proto-Atlantic and Tethyan oceans and interior seaways. Considering these gaps in spatial coverage, the pervasive increase in organic carbon (OC) burial during OAE2 that drove carbon isotope values more positive (average of 4‰) can provide additional insight. These isotope data allow us to estimate the total global burial of OC, even for unstudied portions of the global ocean. Thus, we can solve for any `missing' OC sinks by comparing our estimates from a forward carbon-isotope box model with the known, mapped distribution of OC for OAE 2 sediments. Using the known OC distribution and reasonably extrapolating to the surrounding regions of analogous depositional conditions accounts for only 13% of the total seafloor, mostly in marginal marine settings. This small geographic area accounts for more OC burial than the entire modern ocean, but significantly less than the amount necessary to produce the observed isotope record. Using modern and OAE 2 average OC rates we extrapolate further to appropriate depositional settings in the unknown portions of seafloor, mostly deep abyssal plains. This addition significantly increases the predicted amount buried but still does not account for total burial. Additional sources, including hydrocarbon migration, lacustrine, and coal also cannot account for the missing OC. This difference points to unknown portions of the open ocean with high TOC contents or exceptionally high TOC in productive marginal marine regions, which are underestimated in our extrapolations. This difference might be explained by highly productive margins within the

  14. Observations on Dissocladella annulata (Elliott, 1993 nov. comb. (Calcareous algae, Dasycladales from the Cenomanian of west Serbia

    Radoičić Rajka

    2010-01-01

    Full Text Available Based on material from the type area at Tetrebovo in the Zlatibor massif of WSerbia, the Cenomanian dasycladalean alga originally described as Harlanjohnsonella annulata by ELLIOTT (1968, typified 1993 in: GRANIER & DELOFFRE, is emended and revisited as Dissocladella annulata (ELLIOTT nov. comb. The evidence of tufts of short secondaries arising at the top of the drop-like primaries allows its transfer to the genus Dissocladella PIA, 1936. This species displays a different degree of skeleton calcification which is described in detail. The monospecific genus Harlanjohnsonella ELLIOTT becomes invalid, as being a junior synonym of Dissocladella.

  15. A new schizaeaceous fern, Schizaeopsis ekrtii sp nov., and its in situ spores from the Upper Cretaceous (Cenomanian) of the Czech Republic

    Kvaček, J.; Dašková, Jiřina; Pátová, R.

    2006-01-01

    Roč. 140, 1-2 (2006), s. 51-60 ISSN 0034-6667 R&D Projects: GA ČR GA205/03/1267 Institutional research plan: CEZ:AV0Z30130516 Keywords : fern * palaeobotany * spores * Cenomanian Subject RIV: EF - Botanics Impact factor: 1.170, year: 2006

  16. Carbon and oxygen stable isotopes of selected Cenomanian and Turonian rudists from Egypt and Czech Republic, and a note on changes in rudist diversity

    El-Shazly, S.; Košťák, M.; Abdel-Gawad, G.; Kloučková, B.; Saber, G. S.; Salama, Y. F.; Mazuch, M.; Žák, Karel

    2011-01-01

    Roč. 86, č. 2 (2011), s. 209-226 ISSN 1214-1119 Institutional research plan: CEZ:AV0Z30130516 Keywords : rudists * Upper Cretaceous * Cenomanian * Turonian * paleoecology * C and O stable isotopes * Upper Cretaceous (Egypt) * Upper Cretaceous (Czech Republic) Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.099, year: 2011

  17. Silicified sea life - Macrofauna and palaeoecology of the Neuburg Kieselerde Member (Cenomanian to Lower Turonian Wellheim Formation, Bavaria, southern Germany)

    Schneider, S.; Jäger, M.; Kroh, A.; Mitterer, A.; Niebuhr, B.; Vodrážka, Radek; Wilmsen, M.

    2013-01-01

    Roč. 63, č. 4 (2013), s. 555-610 ISSN 0001-5709 Institutional support: RVO:67985831 Keywords : Late Cretaceous * Danubian Cretaceous Group * Macro-invertebrates * Facies Silica diagenesis * stratigraphy Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.804, year: 2013

  18. Integrated foraminiferal biostratigraphy and chemostratigraphy of the querecual formation (Cretaceous), Eastern Venezuela

    Crespo De Cabrera, S.; Sliter, W.V.; Jarvis, I.

    1999-01-01

    An integrated foraminiferal biostratigraphy and chemostratigraphy is presented for the Lower to Upper Cretaceous Querecual Formation exposed on Chimana Grande Island, Eastern Venezuela. The formation consists of >450 m alternating foraminiferal and organic-rich carbonates and laminated mudrocks, and is considered the main hydrocarbon source rock for the eastern Venezuela Basin. Biostratigraphic resolution within the Querecual Formation is poor, due to a paucity of keeled planktonic foraminifera and impoverished benthic faunas. Deposition occurred in a bathyal environment, with dysaerobic or anoxic bottom waters resulting from high rates of surface productivity associated with an upwelling environment. Biostratigraphic evidence indicates that the Querecual Formation ranges from the upper Albian Rotalipora ticinensis Zone to the Santonian Dicarinella asymetrica Zone. Iron and Al contents fall through the Albian-Cenomanian indicating a progressive decrease in the detrital supply, driven by rising eustatic sea level. A Ca profile demonstrates variations in carbonate production and dissolution. High total organic carbon (TOC) intervals occur in the upper Albian to mid-Cenomanian and Turonian, and high Ba/Al and Si/Al ratios characterize mid-Cenomanian and younger sediments. Variations in these elements primarily reflect changes in marine productivity, but are also affected by diagenetic processes. A stable carbon isotope curve established from analysis of organic matter (??13Corg) correlates well with published ??13C curves for carbonates from England and Italy. The Cenomanian/Turonian boundary cannot be identified using planktonic foraminifera, because key taxa are absent, but the base of the Turonian is clearly indicated by a sharp fall in ??13C immediately above a major positive excursion. The bottom of the Coniacian is placed below a ??13C minimum, towards the base of the Dicarinella concavata Zone. Combined with the foraminiferal data, the isotopic data enable much

  19. Productivity, facies and stable-isotope records of OAE2 (Cenomanian - Turonian) in the NW European epicontinental sea: from the English Chalk to North Sea black shales

    Jarvis, Ian; Olde, Kate; Trabucho-Alexandre, João; Gröcke, Darren

    2013-04-01

    The Late Cretaceous (100.5 - 66.0 Ma) provides perhaps the best example of how the Earth System may function under long-term extreme greenhouse conditions. Rapidly rising global temperatures indicate that we are heading 'back to the Cretaceous' within a few hundred years, so a better understanding of this time interval is essential. The beginning of the Late Cretaceous was characterized by a period of rapidly rising eustatic sea level, the Cenomanian transgression, which flooded continental margins and established large areas of new epicontinental sea that accumulated thick sequences of pelagic and hemipelagic carbonate (chalk). Highest global temperatures were reached during the early part of the Turonian Stage (93.9 - 89.8 Ma). This period of dramatic palaeoenvironmental change was accompanied by one the largest perturbations of the global carbon cycle in the Mesozoic: Oceanic Anoxic Event 2 (OAE2), which was characterized by a 500 kyr episode of oceanic anoxia, widespread black shale deposition, biotic turnover, and a large global positive carbon stable-isotope excursion (2 - 6 ‰ ∂13C) recorded in marine carbonates and both marine and terrestrial organic matter. The Cenomanian-Turonian boundary interval exposed at Eastbourne, southern England, has become established as a European reference section for OAE2. Here, and elsewhere in Europe, the base of the ∂13C excursion is coincident with a marked facies change from rhythmically bedded grey chalks and marls, to a >8 m thick package of dark greenish-grey marl - the Plenus Marl. The termination of OAE2 occurs 6 m above, in a package of pale-yellow-weathering nodular chalks with prominent marl seams. Sediments are organic lean (10 wt%. The onshore equivalent in eastern England (the Black Band) is similarly organic-rich, as are comparable sections in northern Germany (e.g. Wunstorf), indicating likely fully anoxic episodes within some NW European basins. The exact stratigraphic equivalence between the onshore

  20. Enrichment Of Volcanogenic Trace Elements, Co, Cr, Cu, Ni, Mo And Zr In A Continuous Subsurface Eagle Ford Core In South Texas And Origin Of The Oceanic Anoxic Event II At The Cenomanian-Turonian (C/T) Boundary

    Valencia, D.; Basu, A. R.; Loocke, M. P.

    2017-12-01

    The Eagle Ford Formation containing the Cenomanian-Turonian (C/T) boundary continues to be studied globally not only for its economic potential and analog for `frack-able' unconventional organic-rich formations, but it is of particular interest to researchers because it was deposited across the C/T boundary recording an Oceanic Anoxic Event (OAE2). OAEs are short lived episodes (matter into the sedimentary record remains enigmatic. Geochemical and geochronological analysis of a subsurface 300ft long continuous core of the Eagle Ford Formation of South Texas shows evidence for volcanism throughout. This is confirmed by multiple thin intermittent bentonite beds. The whole rock black shale (marl) shows elevated concentrations of volcanogenic trace elements (Co, Cr, Cu, Ni, Mo and Zn) throughout the core. By sampling bentonite bed zircons near the inferred C/T boundary, U-Pb age of 93.2 ±1.7 Ma for the Eagle Ford is established. Using this horizon, the onset of OAE2 is constrained and well-correlated with the positive δ13C excursion. For the trace element analysis, the core was sampled at 10ft intervals for ICP-MS. The analytical results show significantly increased volcanogenic trace metal input correlating with increased Total Organic Carbon and positive δ13C values at the C/T dated zircon horizon. OAE2, defined by the positive δ13C excursion, was found to span over an interval of 85ft. With a definitive constraint for OAE2 established, this well-defined interval was analyzed at a much higher resolution using ED-XRF. The core was then sampled at 6' intervals throughout the C/T boundary at OAE2. The high-resolution sampling of the core shows 80-99% increase in abundance of Co, Cr, Cu, Ni, Mo, Zn over the average Post Australian Archean Shale(PAAS), representative of average continental crust. These volcanogenic-rich intervals reach peak values before the onset of OAE2 and at the maximum values for the positive δ13C isotope excursion directly after the 93.2 ±1

  1. Definition of Greater Gulf Basin Lower Cretaceous and Upper Cretaceous Lower Cenomanian Shale Gas Assessment Unit, United States Gulf of Mexico Basin Onshore and State Waters

    Dennen, Kristin O.; Hackley, Paul C.

    2012-01-01

    An assessment unit (AU) for undiscovered continuous “shale” gas in Lower Cretaceous (Aptian and Albian) and basal Upper Cretaceous (lower Cenomanian) rocks in the USA onshore Gulf of Mexico coastal plain recently was defined by the U.S. Geological Survey (USGS). The AU is part of the Upper Jurassic-Cretaceous-Tertiary Composite Total Petroleum System (TPS) of the Gulf of Mexico Basin. Definition of the AU was conducted as part of the 2010 USGS assessment of undiscovered hydrocarbon resources in Gulf Coast Mesozoic stratigraphic intervals. The purpose of defining the Greater Gulf Basin Lower Cretaceous Shale Gas AU was to propose a hypothetical AU in the Cretaceous part of the Gulf Coast TPS in which there might be continuous “shale” gas, but the AU was not quantitatively assessed by the USGS in 2010.

  2. Sedimentary Mercury Enrichments as a Marker for Submarine Large Igneous Province Volcanism? Evidence From the Mid-Cenomanian Event and Oceanic Anoxic Event 2 (Late Cretaceous)

    Scaife, J. D.; Ruhl, M.; Dickson, A. J.; Mather, T. A.; Jenkyns, H. C.; Percival, L. M. E.; Hesselbo, S. P.; Cartwright, J.; Eldrett, J. S.; Bergman, S. C.; Minisini, D.

    2017-12-01

    Oceanic Anoxic Event 2 (OAE 2), during the Cenomanian-Turonian transition (˜94 Ma), was the largest perturbation of the global carbon cycle in the mid-Cretaceous and can be recognized by a positive carbon-isotope excursion in sedimentary strata. Although OAE 2 has been linked to large-scale volcanism, several large igneous provinces (LIPs) were active at this time (e.g., Caribbean, High Arctic, Madagascan, Ontong-Java) and little clear evidence links OAE 2 to a specific LIP. The Mid-Cenomanian Event (MCE, ˜96 Ma), identified by a small, 1‰ positive carbon-isotope excursion, is often referred to as a prelude to OAE 2. However, no underlying cause has yet been demonstrated and its relationship to OAE 2 is poorly constrained. Here we report sedimentary mercury (Hg) concentration data from four sites, three from the southern margin of the Western Interior Seaway and one from Demerara Rise, in the equatorial proto-North Atlantic Ocean. We find that, in both areas, increases in mercury concentrations and Hg/TOC ratios coincide with the MCE and the OAE 2. However, the increases found in these sites are of a lower magnitude than those found in records of many other Mesozoic events, possibly characteristic of a marine rather than atmospheric dispersal of mercury for both events. Combined, the new mercury data presented here are consistent with an initial magmatic pulse at the time of the MCE, with a second, greater pulse at the onset of OAE 2, possibly related to the emplacement of LIPs in the Pacific Ocean and/or the High Arctic.

  3. Paired carbon stable-isotope records for the Cenomanian Stage (100.5 -93.9 Ma): correlation tool and Late Cretaceous pCO2 record?

    Jarvis, Ian; Gröcke, Darren; Laurin, Jiří; Selby, David; Roest-Ellis, Sascha; Miles, Andrew; Lignum, John; Gale, Andrew; Kennedy, Jim

    2016-04-01

    Carbon stable-isotope stratigraphy of marine carbonates (δ13Ccarb) provides remarkable insights into past variation in the global carbon cycle, and has become firmly established as a powerful global correlation tool. Continuous δ13Ccarb time series are becoming increasingly available for much of the geological record, including the Upper Cretaceous. However, our knowledge of stratigraphic variation in the carbon isotopic composition of sedimentary organic matter (δ13Corg) is much poorer, and is generally restricted to organic-rich sedimentary successions and/or key boundary intervals. Close coupling exists between the global isotopic composition of the reduced and oxidised carbon reservoirs on geological time scales, but the stratigraphic resolution of most long-term δ13Corg Mesozoic records is inadequate to identify leads and lags in the responses of the two reservoirs to carbon cycle perturbations. Cenomanian times (100.5-93.9 Ma) represent perhaps the best documented episode of eustatic rise in sea level in Earth history and the beginning of the Late Mesozoic thermal maximum, driving global expansion of epicontinental seas and the onset of widespread pelagic and hemipelagic carbonate deposition. Significant changes occurred in global stable-isotope records, including two prominent perturbations of the carbon cycle - the Mid-Cenomanian Event I (MCEI; ~96.5-96.2 Ma) and Oceanic Anoxic Event 2 (OAE2; ~94.5-93.8 Ma). OAE2, one of two truly global Cretaceous OAEs, was marked by the widespread deposition of black shales, and a global positive carbon stable-isotope excursion of 2.0 - 2.5‰ δ13Ccarb, and up to 7‰ in the sulphur-bound phytane biomarker. MCEI, by contrast, shows a English Chalk reference section at Folkestone, and correlate the carbon-isotope events between England, France, Germany and Italy. Comparison of the Vergons δ13Ccarb vs. δ13Corg profiles demonstrates similar medium-term stratigraphic variation, but significant differences in both short

  4. Regional hardening of Upper Cretaceous Chalk in eastern England, UK: trace element and stable isotope patterns in the Upper Cenomanian and Turonian Chalk and their significance

    Jeans, Christopher V.; Long, Dee; Hu, Xiu-Fang; Mortimore, Rory N.

    2014-12-01

    The regional hardening of the Late Cenomanian to Early Turonian Chalk of the Northern Province of eastern England has been investigated by examining the pattern of trace elements and stable carbon and oxygen isotopes in the bulk calcite of two extensive and stratigraphically adjacent units each 4 to 5 m thick of hard chalk in Lincolnshire and Yorkshire. These units are separated by a sequence, 0.3-1.3 m thick, of variegated marls and clayey marls. Modelling of the geochemistry of the hard chalk by comparison with the Standard Louth Chalk, combined with associated petrographic and geological evidence, indicates that (1) the hardening is due to the precipitation of a calcite cement, and (2) the regional and stratigraphical patterns of geochemical variation in the cement are largely independent of each other and have been maintained by the impermeable nature of the thin sequence of the clay-rich marls that separate them. Two phases of calcite cementation are recognised. The first phase was microbially influenced and did not lithify the chalk. It took place predominantly in oxic and suboxic conditions under considerable overpressure in which the Chalk pore fluids circulated within the units, driven by variations in compaction, temperature, pore fluid pressure and local tectonics. There is evidence in central and southern Lincolnshire of the loss of Sr and Mgenriched pore fluids to the south during an early part of this phase. The second phase of calcite precipitation was associated with the loss of overpressure in probably Late Cretaceous and in Cenozoic times as the result of fault movement in the basement penetrating the overlying Chalk and damaging the seal between the two chalk units. This greatly enhanced grain pressures, resulting in grain welding and pressure dissolution, causing lithification with the development of stylolites, marl seams, and brittle fractures. Associated with this loss of overpressure was the penetration of the chalk units by allochthonous

  5. Paleodepositional environment and age of Kanawa Member of Pindiga Formation, Gongola Sub-basin, Northern Benue Trough, NE Nigeria: Sedimentological and palynological approach

    Aliyu, Abdulkarim H.; Mamman, Y. D.; Abubakar, M. B.; Sarki Yandoka, Babangida M.; Jitong, John Shirputda; Shettima, Bukar

    2017-10-01

    Sedimentogical and palynological investigations of the Kanawa Member of Pindiga Formation in the Gongola Sub-basin, Northern Benue Trough, NE Nigeria were carried out in order to determine the paleoenvironment and age of the sediments. Three main lithofacies were identified from the measured sedimentary log section, namely; the wave rippled sandstones, the limestones (with ammonites, bivalves and gastropods) and the clay-shale. The facies were interpreted to have been deposited in a marine environment. Based on palynological studies, Kanawa Member consists of two palynozones, namely; Cretacaeiporites scabratus and Triorites africaensis. The Triorites africaensis zone is characterized by species of T. africaensis, Gnetaceaepollenites sp. 1, Cretacaeiporites polygonalis, Monosulcites sp., Cretacaeiporites scabratus, Elaterocolpites castelainii and is dated Late Cenomanian whilst the Cretacaeiporites scabratus zone is characterized by the dominance of C. scabratus, C. mulleri and Tricolporopollenites sp and is dated Early Turonian. The Kanawa Member is therefore, dated Late Cenomanian to early Turonian.

  6. A PLIOSAURID TOOTH FROM THE ARGILLE VARICOLORI FORMATION NEAR CASTELVECCHIO DI PRIGNANO (MODENA PROVINCE, NORTHERN ITALY

    CESARE A. PAPAZZONI

    2003-11-01

    Full Text Available The first discovery of a Cretaceous pliosaurid tooth in Italy is reported. It comes from the Cenomanian-lower Campanian Argille Varicolori Formation near Castelvecchio di Prignano (Modena Province, northern Italy. Excepting this new specimen, Italy's only reported pliosaurid is a humerus from the Upper Cretaceous of Zavattarello near Pavia. The tooth morphology allows it to be ascribed to Polyptychodon interruptus Owen, 1841, a species only reported thus far from northern-central Europe (England, Germany, and the Czech Republic. This suggests the presence of marine reptile remains in the northern Apennines may have been underestimated. 

  7. Osteology, Phylogeny, Taphonomy, and Ontogenetic Histology of Oryctodromeus cubicularis, from the Middle Cretaceous (Albian-Cenomanian) of Montana and Idaho

    Krumenacker, L. J.

    Oryctodromeus is a small bipedal dinosaur known from middle Cretaceous (95-100 My) Wayan Formation of Idaho and the Vaughn Member of the Blackleaf Formation of Montana. This taxon is hypothesized to be a burrowing dinosaur, which cared for its young within these burrows. This dissertation is a broad three-part treatment of this taxon, and excepting the introductory and concluding chapters this dissertation consists of three main chapters. Chapter two describes the osteology and phylogenetic relationships of this animal. Notable features of the Oryctodromeus skeleton described include a network of ossified tendons along the vertebral column that completely ensheath the tail, a long tail that forms more than half the length of the animal, and unusual femoral heads whose morphology may be related to burrowing behavior. The first full skeletal and skull reconstructions of this animal are presented. Chapter three investigates patterns of preservation of Oryctodromeus. Data suggests that preservation of single to multiple individuals of this taxon typically occurred in burrows that may be difficult to impossible to recognize in the fossil record. New examples of burrows from Oryctodromeus from the Vaughn and Wayan, as well as additional evidence for social behavior, are also described. A third chapter details the ontogenetic histology, growth rates and patterns of skeletal fusion based on seven limb elements (femora and tibiae) from different individuals. Based on the data in this dissertation, three growth stages can be recognized in Oryctodromeus based on bone histology. Juveniles are defined by more rapidly growing fibrolamellar tissue, sub-adults are defined by a cortex of inner fibrolamellar tissue and outer zonal parallel fibered tissue, and near-adult individuals have tissue similar to sub adults with dense avascular bone in the outermost cortex that signals a decrease in growth rate. LAG's suggest a minimum age of six to seven years for more mature individuals

  8. Reducing Error Bars through the Intercalibration of Radioisotopic and Astrochronologic Time Scales for the Cenomanian/Turonian Boundary Interval, Western Interior Basin, USA

    Meyers, S. R.; Siewert, S. E.; Singer, B. S.; Sageman, B. B.; Condon, D. J.; Obradovich, J. D.; Jicha, B.; Sawyer, D. A.

    2010-12-01

    We develop a new intercalibrated astrochronologic and radioisotopic time scale for the Cenomanian/Turonian (C/T) boundary interval near the GSSP in Colorado, where orbitally-influenced rhythmic strata host bentonites that contain sanidine and zircon suitable for 40Ar/39Ar and U-Pb dating. This provides a rare opportunity to directly intercalibrate two independent radioisotopic chronometers against an astrochronologic age model. We present paired 40Ar/39Ar and U-Pb ages from four bentonites spanning the Vascoceras diartianum to Pseudaspidoceras flexuosum biozones, utilizing both newly collected material and legacy sanidine samples of Obradovich (1993). Full 2σ uncertainties (decay constant, standard age, analytical sources) for the 40Ar/39Ar ages, using a weighted mean of 33-103 concordant age determinations and an age of 28.201 Ma for Fish Canyon sanidine (FCs), range from ±0.15 to 0.19 Ma, with ages from 93.67 to 94.43 Ma. The traditional FCs age of 28.02 Ma yields ages from 93.04 to 93.78 Ma with full uncertainties of ±1.58 Ma. Using the ET535 tracer, single zircon CA-TIMS 206Pb/238U ages determined from each bentonite record a range of ages (up to 2.1 Ma), however, in three of the four bentonites the youngest single crystal ages are statistically indistinguishable from the 40Ar/39Ar ages calculated relative to 28.201 Ma FCs, supporting this calibration. Using the new radioisotopic data and published astrochronology (Sageman et al., 2006) we develop an integrated C/T boundary time scale using a Bayesian statistical approach that builds upon the strength of each geochronologic method. Whereas the radioisotopic data provide an age with a well-defined uncertainty for each bentonite, the orbital time scale yields a more highly resolved estimate of the duration between stratigraphic horizons, including the radioisotopically dated beds. The Bayesian algorithm yields a C/T time scale that is statistically compatible with the astrochronologic and radioisotopic data

  9. The Cenomanian-Turonian Oceanic Anoxic Event 2 (OAE2) in the Western Interior US and Gulf of Mexico: Decoupled Black Shale Deposition and Carbon Isotope Excursion

    Lowery, C.; Snedden, J.; Cunningham, R.; Barrie, C.; Leckie, R. M.

    2016-12-01

    The largest carbon isotope excursions (CIEs) of the Cretaceous are associated with widespread evidence for marine anoxia and have been termed Oceanic Anoxic Events (OAEs). OAEs were originally thought to be globally-correlative intervals of black shales, but black shale deposition is an inherently provincial phenomenon driven by local conditions, and black shales associated with individual OAEs are often slightly diachronous and can be absent in some regions. Workers currently favor a definition of OAEs that is focused on the positive carbon isotope excursion driven by the global burial of organic matter and resulting carbon cycle perturbation; i.e., recording the global, rather than local, changes. While this is certainly the best way to define a global event, differences in the expression of the event between regions can be used to study the nature of the event itself. The greater Gulf of Mexico region in southern North America offers an excellent example of the diachroneity of black shale deposition and anoxia during one of the largest OAEs, the Cenomanian-Turonian OAE2. The Western Interior Seaway (WIS), flooded the interior of North America from the Gulf of Mexico up through the Canadian Arctic. In Texas and elsewhere across the WIS, high marine organic matter deposition and proxies for anoxia (especially benthic foraminifera and redox sensitive trace metals) are common before the event, but decrease at its onset, and in some places increase again after the event. Further south, across the Mexican shelf, deeper shelf environments remain dysoxic/anoxic through the event, while several carbonate platforms remain oxygenated during the event, but drown and record anoxic bottom waters shortly afterward. Here, we present new bulk carbonate and organic carbon isotopes and planktic and benthic foraminiferal populations from a 90 m core in southern Mississippi, USA, to present the first record of OAE2 from the northern Gulf of Mexico. In particular, we use

  10. Biostratigraphy of the Garau Formation in Naft well subsurface stratigraphic section, South Kermanshah

    Y., Ezampanah,

    2012-01-01

    Full Text Available In order to biostratigraphy of the Garau Formation in the centeral Lurestan, one subsurface section (Naft well in Naft anticline, south Kermanshah was selected and studied. The drilled thickness of the Garau Formation in this section is up to 485 meters and lithologically composed of argillaceous limestones and dark gray marls. In this research 1150 thin sections of subsurface Naft well section were studied. In biostratigraphic studies of the Garau Formation in study section 61 species belong to 17 genera of planktonic foraminifera were recognized and 9 biozones were identified. Based on distribution of fossils and biozones identificated, the age of the Garau Formation in drilled part of the subsurface Naft well section is Early Aptian to Early Cenomanian.

  11. U-Pb zircon constraints on the age of the Cretaceous Mata Amarilla Formation, Southern Patagonia, Argentina: Its relationship with the evolution of the Austral Basin

    Varela, Augusto N; Poire, Daniel G; Martin, Thomas; Gerdes, Axel; Goin, Francisco J; Gelfo, Javier N; Hoffmann, Simone

    2012-01-01

    Despite the abundant fossil content of the Mata Amarilla Formation (Southern Patagonia, Santa Cruz Province, Argentina), its age has always generated a considerable number of questions and debates. The chronological data provided by invertebrates, dinosaurs, fish, turtles, plesiosaurs and fossil flora are contradictory. In this work, twenty U-Pb spot analyses by laser ablation were carried out on the outer parts of the zoned zircon crystals from a tuff layer of the middle section of the Mata Amarilla Formation, yielding a U-Pb concordia age of 96.23±0.71 Ma, which corresponds to the middle Cenomanian. The deposition of the lower section of the Mata Amarilla Formation marks the onset of the foreland stage of the Austral Basin (also known as Magallanes Basin); this transition is characterized by the west-east shift of the depositional systems, which is consistent with the progradation of the Cretaceous fold-and-thrust belt. Thus, the onset of the foreland stage could have occurred between the upper Albian and lower Cenomanian, as the underlying Piedra Clavada Formation is lower Albian in age. On comparing the data obtained with information from the Ultima Esperanza Province in Chile, it can be suggested that the initiation of the closure of the Rocas Verdes Marginal Basin occurred simultaneously

  12. Paleoceanographic Inferences from Carbon and Nitrogen Isotopic Compositions of Cenomanian Black Shales from DSDP/ODP Sites 367, 530, 603, 641, 1257-1261, and 1276 in the Atlantic Ocean

    Yum, J.; Meyers, P. A.; Bernasconi, S. M.; Arnaboldi, M.

    2005-12-01

    The mid-Cretaceous (Cenomanian- Turonian) was characterized as a peak global greenhouse period with highest sea level, highest CO2 concentration in atmosphere and low thermal gradients from the poles to the equator. The depositional environment of the organic-carbon-rich black shales that typify this period remains an open question. A total of 180 Cenomanian- Turonian core samples were selected from multiple ODP and DSDP sites in the Atlantic Ocean: 530 (Cape Basin), 603 (Hatteras Rise), 641 (Galicia Bank), 1257-1261 (Demerara Rise), 1276 (Newfoundland Basin). Total organic carbon and nitrogen concentrations and isotopic compositions were measured to investigate variations in the proto-Atlantic Ocean paleoceanographic conditions that contributed to the origin of the black shales for this period. These new data were combined with existing data from Sites 367 (Senegal Rise), 530, and 603. Both the black shales and the organic-carbon-poor background sediments (less than 1 percent) have carbon isotope values between -29 to -22 permil. The C/N ratios of the background sediments are low (less than 20) compared to those of the black shales (20-40). Nitrogen isotope values range from 0 to 4 permil in the background samples. All black shales have similarly low nitrogen isotope values that range between -4 to 0 permil. These exceptionally low values are inferred to reflect the productivity of blue green algae and cyanobacteria under strongly surface stratified oceanic conditions. Although carbon isotope and C/N values of black shales show almost similar patterns at each location, there are site-specific shifts in these data that could be related to the amount of continental run off and/or the effect of latitude. Our multi-site comparison suggests that specially stratified depositional environments that could produce and accumulate the abnormally high carbon concentrations in sediments occurred throughout the proto-Atlantic ocean during the mid-Cretaceous. However, regional

  13. Geologic assessment of undiscovered oil and gas resources—Lower Cretaceous Albian to Upper Cretaceous Cenomanian carbonate rocks of the Fredericksburg and Washita Groups, United States Gulf of Mexico Coastal Plain and State Waters

    Swanson, Sharon M.; Enomoto, Catherine B.; Dennen, Kristin O.; Valentine, Brett J.; Cahan, Steven M.

    2017-02-10

    In 2010, the U.S. Geological Survey (USGS) assessed Lower Cretaceous Albian to Upper Cretaceous Cenomanian carbonate rocks of the Fredericksburg and Washita Groups and their equivalent units for technically recoverable, undiscovered hydrocarbon resources underlying onshore lands and State Waters of the Gulf Coast region of the United States. This assessment was based on a geologic model that incorporates the Upper Jurassic-Cretaceous-Tertiary Composite Total Petroleum System (TPS) of the Gulf of Mexico basin; the TPS was defined previously by the USGS assessment team in the assessment of undiscovered hydrocarbon resources in Tertiary strata of the Gulf Coast region in 2007. One conventional assessment unit (AU), which extends from south Texas to the Florida panhandle, was defined: the Fredericksburg-Buda Carbonate Platform-Reef Gas and Oil AU. The assessed stratigraphic interval includes the Edwards Limestone of the Fredericksburg Group and the Georgetown and Buda Limestones of the Washita Group. The following factors were evaluated to define the AU and estimate oil and gas resources: potential source rocks, hydrocarbon migration, reservoir porosity and permeability, traps and seals, structural features, paleoenvironments (back-reef lagoon, reef, and fore-reef environments), and the potential for water washing of hydrocarbons near outcrop areas.In Texas and Louisiana, the downdip boundary of the AU was defined as a line that extends 10 miles downdip of the Lower Cretaceous shelf margin to include potential reef-talus hydrocarbon reservoirs. In Mississippi, Alabama, and the panhandle area of Florida, where the Lower Cretaceous shelf margin extends offshore, the downdip boundary was defined by the offshore boundary of State Waters. Updip boundaries of the AU were drawn based on the updip extent of carbonate rocks within the assessed interval, the presence of basin-margin fault zones, and the presence of producing wells. Other factors evaluated were the middle

  14. A regional ocean circulation model for the mid-Cretaceous North Atlantic Basin: implications for black shale formation

    R. P. M. Topper

    2011-03-01

    Full Text Available High concentrations of organic matter accumulated in marine sediments during Oceanic Anoxic Events (OAEs in the Cretaceous. Model studies examining these events invariably make use of global ocean circulation models. In this study, a regional model for the North Atlantic Basin during OAE2 at the Cenomanian-Turonian boundary has been developed. A first order check of the results has been performed by comparison with the results of a recent global Cenomanian CCSM3 run, from which boundary and initial conditions were obtained. The regional model is able to maintain tracer patterns and to produce velocity patterns similar to the global model. The sensitivity of the basin tracer and circulation patterns to changes in the geometry of the connections with the global ocean is examined with three experiments with different bathymetries near the sponges. Different geometries turn out to have little effect on tracer distribution, but do affect circulation and upwelling patterns. The regional model is also used to test the hypothesis that ocean circulation may have been behind the deposition of black shales during OAEs. Three scenarios are tested which are thought to represent pre-OAE, OAE and post-OAE situations. Model results confirm that Pacific intermediate inflow together with coastal upwelling could have enhanced primary production during OAE2. A low sea level in the pre-OAE scenario could have inhibited large scale black shale formation, as could have the opening of the Equatorial Atlantic Seaway in the post-OAE scenario.

  15. On the possibility of occurrence of uranium mineralization in some sedimentary formations of the Sudety Mts

    Miecznik, J.B.; Strzelecki, R.

    1979-01-01

    The Sudety Mts represent a part of the Bohemian Massif which is one of the richest uranium-bearing regions in Europe. The possibilities of occurrence of uranium in most interesting sedimentary formations of the Sudety Mts are analysed. The sedimentary formations which originated during the platform stage of evolution of these Mountains, after formation of Variscan endogenic mineralization, were recognized as perspective here. Sandstone-type uranium deposits and uraniferous black shales were assumed to be the most important in that area. Sandstone-type uranium deposits are related to continental uppermost Carboniferous (Glinik Beds - Westphalian C-D and, possibly, lowermost Stephanian) of the Central Sudety (Intra-Sudetic Depression). They closely resemble uranium deposits known from continental clastic Permo-Carboniferous sections of several parts of Europe. Westphalian D and Stephanian rocks developed in similar lithofacies in the western Sudety Mts (North-Sudetic Depression) may be also characterized by increased content of uranium. Attention is also paid to the possibilities of occurrence of uranium mineralization in shallow-marine sandstones and continental deposits of the Cenomanian as uranium deposits are known from similarly developed Cenomanian in the North Czech Upper Cretaceous Table area, i.e. in the direct neighbourhood of the Sudety Mts. Traces of uranium mineralization were found in black shales of the Lower Silurian section in the Kaczawa Mts (western Sudety Mts) and Bardo Mts (Central Sudety). The recorded concentrations (up to several hundred ppm) may be compared with uranium occurrences known from Lower Silurian sections of the Barrandian (CSSR) and Thuringia (GDR). (author)

  16. Field guide to Muddy Formation outcrops, Crook County, Wyoming

    Rawn-Schatzinger, V.

    1993-11-01

    The objectives of this research program are to (1) determine the reservoir characteristics and production problems of shoreline barrier reservoirs; and (2) develop methods and methodologies to effectively characterize shoreline bamer reservoirs to predict flow patterns of injected and produced fluids. Two reservoirs were selected for detailed reservoir characterization studies -- Bell Creek field, Carter County, Montana that produces from the Lower Cretaceous (Albian-Cenomanian) Muddy Formation, and Patrick Draw field, Sweetwater County, Wyoming that produces from the Upper Cretaceous (Campanian) Almond Formation of the Mesaverde Group. An important component of the research project was to use information from outcrop exposures of the producing formations to study the spatial variations of reservoir properties and the degree to which outcrop information can be used in the construction of reservoir models. This report contains the data and analyses collected from outcrop exposures of the Muddy Formation, located in Crook County, Wyoming, 40 miles south of Bell Creek oil field. The outcrop data set contains permeability, porosity, petrographic, grain size and geologic data from 1-inch-diameter core plugs chilled from the outcrop face, as well as geological descriptions and sedimentological interpretations of the outcrop exposures. The outcrop data set provides information about facies characteristics and geometries and the spatial distribution of permeability and porosity on interwell scales. Appendices within this report include a micropaleontological analyses of selected outcrop samples, an annotated bibliography of papers on the Muddy Formation in the Powder River Basin, and over 950 permeability and porosity values measured from 1-inch-diameter core plugs drilled from the outcrop. All data contained in this resort are available in electronic format upon request. The core plugs drilled from the outcrop are available for measurement.

  17. Facies and sedimentary environments of the Abu Qada Formation at Gabal El-Gunna, Southeastern Sinai, Egypt

    Tarek Y.M.A. El-Hariri

    2012-06-01

    Full Text Available The biostratigraphy, microfacies association, mineralogical interferences, depositional environments and geochemical properties of the Abu Qada Formation, which exposed at Gabal El-Gunna Southeastern Sinai, Egypt were delineated. It belongs to the planktonic foraminiferal Whiteinella archaeocretacea Zone of the Late Cenomanian-Early Turonian and consists of calcareous shale and limestone. The calcareous shale facies is characterized by chlorite, smectite and illite with high concentration of P2O5, Zn, Ni, V, and Cr. The carbonate rocks are characterized by foraminiferal wakestone and bioclastic grainstone. These microfacies associations are characterized by barite with high content of Sr. The facies types with faunal contents, geochemical and mineralogical studies suggest a restricted to shelf lagoon open circulation environment.

  18. Paleomagnetism of the Cretaceous Galula Formation and implications for vertebrate evolution

    Widlansky, Sarah J.; Clyde, William C.; O'Connor, Patrick M.; Roberts, Eric M.; Stevens, Nancy J.

    2018-03-01

    This study uses magnetostratigraphy to help constrain the age of the paleontologically important Galula Formation (Rukwa Rift Basin, southwestern Tanzania). The formation preserves a Cretaceous vertebrate fauna, including saurischian dinosaurs, a putative gondwanatherian mammal, and notosuchian crocodyliforms. With better dating, the Galula Formation and its fossils help fill a temporal gap in our understanding of vertebrate evolution in continental Africa, enabling better evaluation of competing paleobiogeographic hypotheses concerning faunal exchange throughout Gondwana during the Cretaceous. Paleomagnetic samples for this study were collected from the Namba (higher in section) and Mtuka (lower in section) members of the Galula Formation and underwent stepwise thermal demagnetization. All samples displayed a strong normal magnetic polarity overprint, and maximum unblocking temperatures at approximately 690 °C. Three short reversed intervals were identified in the Namba Member, whereas the Mtuka Member lacked any clear reversals. Given the relatively limited existing age constraints, one interpretation correlates the Namba Member to Chron C32. An alternative correlation assigns reversals in the Namba Member to recently proposed short reversals near the end of the Cretaceous Normal Superchron (Chron C34), a time that is traditionally interpreted as having stable normal polarity. The lack of reversals in the Mtuka Member supports deposition within Chron C34. These data suggest that the Namba Member is no older than Late Cretaceous (Cenomanian-Campanian), with the Mtuka Member less well constrained to the middle Cretaceous (Aptian-Cenomanian). The paleomagnetic results are supported by the application of fold and reversal tests for paleomagnetic stability, and paleomagnetic poles for the Namba (246.4°/77.9°, α95 5.9°) and Mtuka (217.1°/72.2°, α95 11.1°) members closely matching the apparent polar wander path for Africa during the Late Cretaceous. These

  19. Data from selected Almond Formation outcrops -- Sweetwater County, Wyoming

    Jackson, S.R.; Rawn-Schatzinger, V.

    1993-12-01

    The objectives of this research program are to: (1) determine the reservoir characteristics and production problems of shoreline barrier reservoirs; and (2) develop methods and methodologies to effectively characterize shoreline barrier reservoirs to predict flow patterns of injected and produced fluids. Two reservoirs were selected for detailed reservoir characterization studies -- Bell Creek field, Carter County, Montana, that produces from the Lower Cretaceous (Albian-Cenomanian) Muddy Formation, and Patrick Draw field, Sweetwater County, Wyoming that produces from the Upper Cretaceous (Campanian) Almond Formation of the Mesaverde Group. An important component of the research project was to use information from outcrop exposures of the producing formations to study the spatial variations of reservoir properties and the degree to which outcrop information can be used in the construction of reservoir models. A report similar to this one presents the Muddy Formation outcrop data and analyses performed in the course of this study (Rawn-Schatzinger, 1993). Two outcrop localities, RG and RH, previously described by Roehler (1988) provided good exposures of the Upper Almond shoreline barrier facies and were studied during 1990--1991. Core from core well No. 2 drilled approximately 0.3 miles downdip of outcrop RG was obtained for study. The results of the core study will be reported in a separate volume. Outcrops RH and RG, located about 2 miles apart were selected for detailed description and drilling of core plugs. One 257-ft-thick section was measured at outcrop RG, and three sections {approximately}145 ft thick located 490 and 655 feet apart were measured at the outcrop RH. Cross-sections of these described profiles were constructed to determine lateral facies continuity and changes. This report contains the data and analyses from the studied outcrops.

  20. Stellar formation

    Reddish, V C

    1978-01-01

    Stellar Formation brings together knowledge about the formation of stars. In seeking to determine the conditions necessary for star formation, this book examines questions such as how, where, and why stars form, and at what rate and with what properties. This text also considers whether the formation of a star is an accident or an integral part of the physical properties of matter. This book consists of 13 chapters divided into two sections and begins with an overview of theories that explain star formation as well as the state of knowledge of star formation in comparison to stellar structure

  1. Galaxy formation

    Silk, J.; Di Cintio, A.; Dvorkin, I.

    2014-01-01

    Galaxy formation is at the forefront of observation and theory in cosmology. An improved understanding is essential for improving our knowledge both of the cosmological parameters, of the contents of the universe, and of our origins. In these lectures intended for graduate students, galaxy formation theory is reviewed and confronted with recent observational issues. In lecture 1, the following topics are presented: star formation considerations, including IMF, star formation efficiency and star formation rate, the origin of the galaxy luminosity function, and feedback in dwarf galaxies. In lecture 2, we describe formation of disks and massive spheroids, including the growth of supermassive black holes, negative feedback in spheroids, the AGN-star formation connection, star formation rates at high redshift and the baryon fraction in galaxies.

  2. Reservoir petrophysics and hydrocarbon occurrences of the Bahariya Formation, Alamein-Yidma fields, Western Desert of Egypt

    Abdel-Aziz Younes, Mohamed [Alexandria Univ. (Egypt). Geology Dept.

    2012-12-15

    The Bahariya Formation of Cenomanian age is considered to be one of the main oil and gas accumulations in most of the fields of the Western Desert basins. The lithostratigraphic succession of the Bahariya Formation is classified into two main sand units (Unit I and Unit III) separated by shalesiltstone (Unit II). The sandstone of unit-I and III is characterized by being highly enriched in shale content especially glauconite in all wells of the Alamein Field, that has an obvious negative effect on the porosity and oil saturation, where the glauconite increases the grain density of sandstone reservoirs from 2.65 g/cm{sup 3} up to 2.71 g/cm{sup 3}. The well logging data and petrophysical characteristics conducted on Alamein well-28 involving analysis of 30 core samples, were used to evaluate the reservoir characterization and hydrocarbon potentialities. The petrophysical parameters indicate that the primary porosity values are between 8.7 and 29.1%. Decreasing porosity is related to the increase of shale content from 9 to 13%, which occurs as a dispersed habitat. The water saturation changes from 43 to 80%, while the hydrocarbon saturation ranges from 12.1 to 37%. Promising hydrocarbon accumulations are displayed by the sandstone of unit-III due to increased hydrocarbon saturation and effective porosity, thus reflecting the high quality reservoir of this unit. The irreducible and movable hydrocarbon distribution shows a general increase at the eastern and western flanks of the faulted anticline in the Alamein-Yidma fields. The biomarker characteristics and stable carbonisotopic composition of the Bahariya crude oils recovered from the Alamein Field show no obvious variations among them. These oils are paraffinic, containing little branched or cyclic materials waxy n-alkanes(C{sub 25}-C{sub 31}) and characterized by high API gravity, low sulfur content, oleanane index < 2% and moderately high pristane/phytaneratio > 1 and CPI > 1 and the canonical variable parameter is

  3. Formative (measurement)

    Fassott, G.; Henseler, Jörg; Cooper, C.; Lee, N.; Farrell, A.

    2015-01-01

    When using measurement models with multiple indicators, researchers need to decide about the epistemic relationship between the latent variable and its indicators. In this article, we describe the nature, the estimation, the characteristics, and the validity assessment of formative measurement

  4. Sedimentary uranium occurrences in Eastern Europe with special reference to sandstone formations

    Barthel, F.; Hahn, L.

    1985-01-01

    Sedimentary uranium deposits, especially in sandstones, play an important role in uranium mining in Eastern Europe. The paper reviews recent publications on uranium occurrences in sandstone formations in the German Democratic Republic, Poland, CSSR, Hungary, Romania, Bulgaria and Albania. The uranium deposits in sandstones in Yugoslavia are described in a separate paper in this volume. Sandstone deposits of the USSR are not reviewed. Uranium mineralizations occur in sandstones from Ordovician to Tertiary age. Major deposits are developed in Upper Carboniferous sandstones in association with coal (GDR, Poland), in Permian strata (CSSR, Hungary, Romania), in Cretaceous sandstones (GDR, CSSR), and in Tertiary sediments (CSSR). The Permian deposits can be compared with deposits of similar age in Northern Italy and Northern Yugoslavia. Roll-type orebodies are developed in some of the Cenomanian sandstones. Tertiary deposits are mainly associated with lignites. Uranium deposits in sandstones of Albania and Bulgaria are not described in the literature. Geologic similarities with sandstone basins in adjacent countries suggest the presence of uranium mineralizations in Permian, Lower Triassic, and Tertiary sandstones. (author)

  5. Properties petrophysics of formation Jandaira: portion west of Potiguar Basin; Propriedades petrofisicas da formacao Jandaira: porcao oeste da Bacia Potiguar

    Silva, Isabelle T.; Vieira, Marcela M.; Bezerra, Francisco H.R. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2008-07-01

    The focus of this study are the carbonate rocks of Jandaira Formation (Cenomanian-Campanian), located in the northeastern Brazil, enclosing, almost in its totality, the Rio Grande do Norte State and a small portion of the Ceara State. The research consisted of field work, petrographic description and petrophysical analysis of samples from surface and subsurface. The objective was to characterize and quantify the porosity and the permeability of this formation. In the qualitative analysis, the types of pores were classified; in the quantitative one, the porosity values were obtained through petrophysical essays and point counting in thin-sections. The samples from subsurface present porosity values less than 10% and permeability values between 0.01 and 0,47 mD. The samples from outcrops present minimum porosity of 0,6%, arriving up to 19.2%, and permeability between 0.0 and 1370,11 mD. In subsurface, the porosity values are higher in comparison with the permeability ones, inferring that, although there is good percentage of pores, they are isolated. In surface, the pores are normally interconnected, resulting in higher values of permeability. This is due to the more intense dissolution processes that rocks under these condition suffer; this fact is observed not only in the field, but in thin-sections, as well. (author)

  6. Late Cretaceous paleosols as paleoclimate proxies of high-latitude Southern Hemisphere: Mata Amarilla Formation, Patagonia, Argentina

    Varela, Augusto N.; Raigemborn, M. Sol; Richiano, Sebastián; White, Tim; Poiré, Daniel G.; Lizzoli, Sabrina

    2018-01-01

    Although there is general consensus that a global greenhouse climate characterized the mid-Cretaceous, details of the climate state of the mid-Cretaceous Southern Hemisphere are less clearly understood. In particular, continental paleoclimate reconstructions are scarce and exclusively derived from paleontological records. Using paleosol-derived climofunction studies of the mid- to Upper Cretaceous Mata Amarilla Formation, southern Patagonia, Argentina, we present a reconstruction of the mid-Cretaceous climate of southern South America. Our results indicate that at 60° south paleolatitude during the Cenomanian-Santonian stages, the climate was subtropical temperate-warm (12 °C ± 2.1 °C) and humid (1404 ± 108 mm/yr) with marked rainfall seasonality. These results are consistent with both previous estimations from the fossil floras of the Mata Amarilla Formation and other units of the Southern Hemisphere, and with the previous observations of the displacement of tropical and subtropical floras towards the poles in both hemispheres. The data presented here show a more marked seasonality and slightly lower mean annual precipitation and mean annual temperature values than those recorded at the same paleolatitudes in the Northern Hemisphere.

  7. Cement Formation

    Telschow, Samira; Jappe Frandsen, Flemming; Theisen, Kirsten

    2012-01-01

    Cement production has been subject to several technological changes, each of which requires detailed knowledge about the high multiplicity of processes, especially the high temperature process involved in the rotary kiln. This article gives an introduction to the topic of cement, including...... an overview of cement production, selected cement properties, and clinker phase relations. An extended summary of laboratory-scale investigations on clinkerization reactions, the most important reactions in cement production, is provided. Clinker formations by solid state reactions, solid−liquid and liquid......−liquid reactions are discussed, as are the influences of particles sizes on clinker phase formation. Furthermore, a mechanism for clinker phase formation in an industrial rotary kiln reactor is outlined....

  8. Star formation

    Woodward, P.R.

    1978-01-01

    Theoretical models of star formation are discussed beginning with the earliest stages and ending in the formation of rotating, self-gravitating disks or rings. First a model of the implosion of very diffuse gas clouds is presented which relies upon a shock at the edge of a galactic spiral arm to drive the implosion. Second, models are presented for the formation of a second generation of massive stars in such a cloud once a first generation has formed. These models rely on the ionizing radiation from massive stars or on the supernova shocks produced when these stars explode. Finally, calculations of the gravitational collapse of rotating clouds are discussed with special focus on the question of whether rotating disks or rings are the result of such a collapse. 65 references

  9. Galaxy Formation

    Sparre, Martin

    Galaxy formation is an enormously complex discipline due to the many physical processes that play a role in shaping galaxies. The objective of this thesis is to study galaxy formation with two different approaches: First, numerical simulations are used to study the structure of dark matter and how...... galaxies form stars throughout the history of the Universe, and secondly it is shown that observations of gamma-ray bursts (GRBs) can be used to probe galaxies with active star formation in the early Universe. A conclusion from the hydrodynamical simulations is that the galaxies from the stateof...... is important, since it helps constraining chemical evolution models at high redshift. A new project studying how the population of galaxies hosting GRBs relate to other galaxy population is outlined in the conclusion of this thesis. The core of this project will be to quantify how the stellar mass function...

  10. Comet formation

    Blum, J.

    2014-07-01

    There has been vast progress in our understanding of planetesimal formation over the past decades, owing to a number of laboratory experiments as well as to refined models of dust and ice agglomeration in protoplanetary disks. Coagulation rapidly forms cm-sized ''pebbles'' by direct sticking in collisions at low velocities (Güttler et al. 2010; Zsom et al. 2010). For the further growth, two model approaches are currently being discussed: (1) Local concentration of pebbles in nebular instabilities until gravitational instability occurs (Johansen et al. 2007). (2) A competition between fragmentation and mass transfer in collisions among the dusty bodies, in which a few ''lucky winners'' make it to planetesimal sizes (Windmark et al. 2012a,b; Garaud et al. 2013). Predictions of the physical properties of the resulting bodies in both models allow a distinction of the two formation scenarios of planetesimals. In particular, the tensile strength (i.e, the inner cohesion) of the planetesimals differ widely between the two models (Skorov & Blum 2012; Blum et al. 2014). While model (1) predicts tensile strengths on the order of ˜ 1 Pa, model (2) results in rather compactified dusty bodies with tensile strengths in the kPa regime. If comets are km-sized survivors of the planetesimal-formation era, they should in principle hold the secret of their formation process. Water ice is the prime volatile responsible for the activity of comets. Thermophysical models of the heat and mass transport close to the comet-nucleus surface predict water-ice sublimation temperatures that relate to maximum sublimation pressures well below the kPa regime predicted for formation scenario (2). Model (1), however, is in agreement with the observed dust and gas activity of comets. Thus, a formation scenario for cometesimals involving gravitational instability is favored (Blum et al. 2014).

  11. The upper to uppermost Cenomanian oceanic anoxic event: a review and an interpretation involving a seawater stratification by the CO{sub 2} of mantle origin; L`evenement oceanique anoxique du Cenomanien superieur-terminal: une revue et une interpretation mettant en jeu une stratification des eaux marines par le CO{sub 2} mantellique

    Busson, G; Cornee, A [Laboratoire de Geologie du Museum, 75 - Paris (France)

    1997-12-31

    Oil exploration data have revealed the exceptional richness of the middle Cretaceous in source rocks worldwide. Oceanic drillings have shown the existence of oceanic anoxic events (OAE) well defined in time. This study analyzes the OAE 2 event dated from the upper Cenomanian-lower Turonian. This event has been recognized in numerous sites from the northern, central and southern Atlantic and punctually in the Pacific and Indian oceans. It occurs in both numerous deep oceanic sites and orogenic zones, and stable platforms covered by epeiric seas. It coincides with a sea level rise which is one of the most sudden and highest in Phanerozoic times and it stands out as a remarkable episode of massive faunal extinction which led to the deposition of organic matter of marine planktonic dominant nature. The first part of the study recalls the previous interpretations of this event (oceanic stratification, euxinic conditions, spreading of an oxygen minimum zone, greenhouse climate effect, sluggish atmospheric and oceanic circulations, high planktonic production, great oceanic overturns, marginal or general upwellings, marine transgressions on epeiric areas etc..). The second part gives the basis of the new hypothesis: connection between separated seas due to the transgression, retreat of evaporite facies, high sea-floor spreading rates, intense volcanic activity and high mantle outgassing with huge CO{sub 2} influxes. The last part describes the proposed interpretation: CO{sub 2} accumulation in deep and intermediate waters and sea overflows on marginal and continental areas which led to a rise of the CO{sub 2}-rich hypolimnion. (J.S.) 236 refs.

  12. The upper to uppermost Cenomanian oceanic anoxic event: a review and an interpretation involving a seawater stratification by the CO{sub 2} of mantle origin; L`evenement oceanique anoxique du Cenomanien superieur-terminal: une revue et une interpretation mettant en jeu une stratification des eaux marines par le CO{sub 2} mantellique

    Busson, G.; Cornee, A. [Laboratoire de Geologie du Museum, 75 - Paris (France)

    1996-12-31

    Oil exploration data have revealed the exceptional richness of the middle Cretaceous in source rocks worldwide. Oceanic drillings have shown the existence of oceanic anoxic events (OAE) well defined in time. This study analyzes the OAE 2 event dated from the upper Cenomanian-lower Turonian. This event has been recognized in numerous sites from the northern, central and southern Atlantic and punctually in the Pacific and Indian oceans. It occurs in both numerous deep oceanic sites and orogenic zones, and stable platforms covered by epeiric seas. It coincides with a sea level rise which is one of the most sudden and highest in Phanerozoic times and it stands out as a remarkable episode of massive faunal extinction which led to the deposition of organic matter of marine planktonic dominant nature. The first part of the study recalls the previous interpretations of this event (oceanic stratification, euxinic conditions, spreading of an oxygen minimum zone, greenhouse climate effect, sluggish atmospheric and oceanic circulations, high planktonic production, great oceanic overturns, marginal or general upwellings, marine transgressions on epeiric areas etc..). The second part gives the basis of the new hypothesis: connection between separated seas due to the transgression, retreat of evaporite facies, high sea-floor spreading rates, intense volcanic activity and high mantle outgassing with huge CO{sub 2} influxes. The last part describes the proposed interpretation: CO{sub 2} accumulation in deep and intermediate waters and sea overflows on marginal and continental areas which led to a rise of the CO{sub 2}-rich hypolimnion. (J.S.) 236 refs.

  13. Planet Formation

    Podolak, Morris

    2018-04-01

    Modern observational techniques are still not powerful enough to directly view planet formation, and so it is necessary to rely on theory. However, observations do give two important clues to the formation process. The first is that the most primitive form of material in interstellar space exists as a dilute gas. Some of this gas is unstable against gravitational collapse, and begins to contract. Because the angular momentum of the gas is not zero, it contracts along the spin axis, but remains extended in the plane perpendicular to that axis, so that a disk is formed. Viscous processes in the disk carry most of the mass into the center where a star eventually forms. In the process, almost as a by-product, a planetary system is formed as well. The second clue is the time required. Young stars are indeed observed to have gas disks, composed mostly of hydrogen and helium, surrounding them, and observations tell us that these disks dissipate after about 5 to 10 million years. If planets like Jupiter and Saturn, which are very rich in hydrogen and helium, are to form in such a disk, they must accrete their gas within 5 million years of the time of the formation of the disk. Any formation scenario one proposes must produce Jupiter in that time, although the terrestrial planets, which don't contain significant amounts of hydrogen and helium, could have taken longer to build. Modern estimates for the formation time of the Earth are of the order of 100 million years. To date there are two main candidate theories for producing Jupiter-like planets. The core accretion (CA) scenario supposes that any solid materials in the disk slowly coagulate into protoplanetary cores with progressively larger masses. If the core remains small enough it won't have a strong enough gravitational force to attract gas from the surrounding disk, and the result will be a terrestrial planet. If the core grows large enough (of the order of ten Earth masses), and the disk has not yet dissipated, then

  14. Galaxy Formation

    Longair, Malcolm S

    2008-01-01

    This second edition of Galaxy Formation is an up-to-date text on astrophysical cosmology, expounding the structure of the classical cosmological models from a contemporary viewpoint. This forms the background to a detailed study of the origin of structure and galaxies in the Universe. The derivations of many of the most important results are derived by simple physical arguments which illuminate the results of more advanced treatments. A very wide range of observational data is brought to bear upon these problems, including the most recent results from WMAP, the Hubble Space Telescope, galaxy surveys like the Sloan Digital Sky Survey and the 2dF Galaxy Redshift Survey, studies of Type 1a supernovae, and many other observations.

  15. Galaxy formation

    Gribbin, J.

    1979-01-01

    The current debate on the origin and evolution of galaxies is reviewed and evidence to support the so-called 'isothermal' and 'adiabatic' fluctuation models considered. It is shown that new theories have to explain the formation of both spiral and elliptical galaxies and the reason for their differences. It is stated that of the most recent models the best indicates that rotating spiral galaxies are formed naturally when gas concentrates in the centre of a great halo and forms stars while ellipticals are explained by later interactions between spiral galaxies and merging, which can cancel out the rotation while producing an elliptical galaxy in which the stars, coming from two original galaxies, follow very elliptical, anisotropic orbits. (UK)

  16. Habit formation.

    Smith, Kyle S; Graybiel, Ann M

    2016-03-01

    Habits, both good ones and bad ones, are pervasive in animal behavior. Important frameworks have been developed to understand habits through psychological and neurobiological studies. This work has given us a rich understanding of brain networks that promote habits, and has also helped us to understand what constitutes a habitual behavior as opposed to a behavior that is more flexible and prospective. Mounting evidence from studies using neural recording methods suggests that habit formation is not a simple process. We review this evidence and take the position that habits could be sculpted from multiple dissociable changes in neural activity. These changes occur across multiple brain regions and even within single brain regions. This strategy of classifying components of a habit based on different brain signals provides a potentially useful new way to conceive of disorders that involve overly fixed behaviors as arising from different potential dysfunctions within the brain's habit network.

  17. Habit formation

    Smith, Kyle S.; Graybiel, Ann M.

    2016-01-01

    Habits, both good ones and bad ones, are pervasive in animal behavior. Important frameworks have been developed to understand habits through psychological and neurobiological studies. This work has given us a rich understanding of brain networks that promote habits, and has also helped us to understand what constitutes a habitual behavior as opposed to a behavior that is more flexible and prospective. Mounting evidence from studies using neural recording methods suggests that habit formation is not a simple process. We review this evidence and take the position that habits could be sculpted from multiple dissociable changes in neural activity. These changes occur across multiple brain regions and even within single brain regions. This strategy of classifying components of a habit based on different brain signals provides a potentially useful new way to conceive of disorders that involve overly fixed behaviors as arising from different potential dysfunctions within the brain's habit network. PMID:27069378

  18. Syn-sedimentary tectonics and facies analysis in a rift setting: Cretaceous Dalmiapuram Formation, Cauvery Basin, SE India

    Nivedita Chakraborty

    2018-04-01

    Full Text Available The Cretaceous (Albian–Cenomanian Dalmiapuram Formation is one of the economically significant constituents in the hydrocarbon-producing Cauvery rift basin, SE India that opened up during the Late Jurassic–Early Cretaceous Gondwanaland fragmentation. The fossil-rich Dalmiapuram Formation, exposed at Ariyalur within the Pondicherry sub-basin of Cauvery Basin, rests in most places directly on the Archean basement and locally on the Lower Cretaceous (Barremian–Aptian Basal Siliciclastic Formation. In the Dalmiapuram Formation, a facies association of tectonically-disturbed phase is sandwiched between two drastically quieter phases. The early syn-rift facies association (FA 1, records the first carbonate marine transgression within the basin, comprising a bar–lagoon system with occasionally storms affecting along the shore and a sheet-like non-recurrent biomicritic limestone bed on the shallow shelf that laterally grades into pyrite–glauconite-bearing dark-colored shale in the deeper shelf. Spectacular breccias together with varied kinds of mass-flow products comprise the syn-rift facies association (FA 2. While the breccias occur at the basin margin area, the latter extend in the deeper inland sea. Clast composition of the coarse clastics includes large, even block-sized limestone fragments and small fragments of granite and sandstone from the basement. Marl beds of quieter intervals between tectonic pulses occur in alternation with them. Faulted basal contact of the formation, and small grabens filled by multiple mass-flow packages bear the clear signature of the syntectonic activity localized contortions, slump folds, and pillow beds associated with mega slump/slide planes and joints, which corroborates this contention further. This phase of tectonic intervention is followed by another relatively quieter phase and accommodates the late syn-rift facies association (FA 3. A tidal bar–interbar shelf depositional system allowed a

  19. Stratigraphy and structural setting of Upper Cretaceous Frontier Formation, western Centennial Mountains, southwestern Montana and southeastern Idaho

    Dyman, T.S.; Tysdal, R.G.; Perry, W.J.; Nichols, D.J.; Obradovich, J.D.

    2008-01-01

    Stratigraphic, sedimentologic, and palynologic data were used to correlate the Frontier Formation of the western Centennial Mountains with time-equivalent rocks in the Lima Peaks area and other nearby areas in southwestern Montana. The stratigraphic interval studied is in the middle and upper parts (but not uppermost) of the formation based on a comparison of sandstone petrography, palynologic age data, and our interpretation of the structure using a seismic line along the frontal zone of the Centennial Mountains and the adjacent Centennial Valley. The Frontier Formation is comprised of sandstone, siltstone, mudstone, limestone, and silty shale in fluvial and coastal depositional settings. A distinctive characteristic of these strata in the western Centennial Mountains is the absence of conglomerate and conglomeratic sandstone beds. Absence of conglomerate beds may be due to lateral facies changes associated with fluvial systems, a distal fining of grain size, and the absence of both uppermost and lower Frontier rocks in the study area. Palynostratigraphic data indicate a Coniacian age for the Frontier Formation in the western Centennial Mountains. These data are supported by a geochronologic age from the middle part of the Frontier at Lima Peaks indicating a possible late Coniacian-early Santonian age (86.25 ?? 0.38 Ma) for the middle Frontier there. The Frontier Formation in the western Centennial Mountains is comparable in age and thickness to part of the Frontier at Lima Peaks. These rocks represent one of the thickest known sequences of Frontier strata in the Rocky Mountain region. Deposition was from about 95 to 86 Ma (middle Cenomanian to at least early Santonian), during which time, shoreface sandstone of the Telegraph Creek Formation and marine shale of the Cody Shale were deposited to the east in the area now occupied by the Madison Range in southwestern Montana. Frontier strata in the western Centennial Mountains are structurally isolated from other

  20. Rates of star formation

    Larson, R.B.

    1977-01-01

    It is illustrated that a theoretical understanding of the formation and evolution of galaxies depends on an understanding of star formation, and especially of the factors influencing the rate of star formation. Some of the theoretical problems of star formation in galaxies, some approaches that have been considered in models of galaxy evolution, and some possible observational tests that may help to clarify which processes or models are most relevant are reviewed. The material is presented under the following headings: power-law models for star formation, star formation processes (conditions required, ways of achieving these conditions), observational indications and tests, and measures of star formation rates in galaxies. 49 references

  1. Why adult formation

    Andrej Justinek

    1997-01-01

    Full Text Available The article argues that the primary aim of adult formation is comprehensive personality development which is supposed to ensure quality existence in modern world. The article also suggests that formarion is a permanent process. Justinek puts special emphasis on adult formation methodology and defines fundamental formation styles which encourage independent action in individuals. Justinek differentiates between formation and education. methods and concludes that formation methods are related to the emotional sphere of personality, and education methods mostly to the rational. Justinek believes that formation of adults is based primarily on appropriate formation methodology.

  2. Formate Formation and Formate Conversion in Biological Fuels Production

    Bryan R. Crable

    2011-01-01

    Full Text Available Biomethanation is a mature technology for fuel production. Fourth generation biofuels research will focus on sequestering CO2 and providing carbon-neutral or carbon-negative strategies to cope with dwindling fossil fuel supplies and environmental impact. Formate is an important intermediate in the methanogenic breakdown of complex organic material and serves as an important precursor for biological fuels production in the form of methane, hydrogen, and potentially methanol. Formate is produced by either CoA-dependent cleavage of pyruvate or enzymatic reduction of CO2 in an NADH- or ferredoxin-dependent manner. Formate is consumed through oxidation to CO2 and H2 or can be further reduced via the Wood-Ljungdahl pathway for carbon fixation or industrially for the production of methanol. Here, we review the enzymes involved in the interconversion of formate and discuss potential applications for biofuels production.

  3. FORMATION CONSTANTS AND THERMODYNAMIC ...

    KEY WORDS: Metal complexes, Schiff base ligand, Formation constant, DFT calculation ... best values for the formation constants of the proposed equilibrium model by .... to its positive charge distribution and the ligand deformation geometry.

  4. Theory of aurora formation

    Hasegawa, Akira.

    1975-04-01

    A new theory of aurora formation is presented based on Alfven wave-electron interaction. The theory explains consistently 1) the electron acceleration process, 2) the formation of auroral layers and 3) the long wave formation in the longitudinal direction. (auth.)

  5. Petrographic Evidence of Microbial Mats in the Upper Cretaceous Fish-Bearing, Organic-Rich Limestone, Agua Nueva Formation, Central Mexico

    Blanco, A.; Maurrasse, F. J.; Hernández-Ávila, J.; Ángeles-Trigueros, S. A.; García-Cabrera, M. E.

    2013-05-01

    We document petrographic evidence of microbial mats in the Upper Cretaceous Agua Nueva Formation in the area of Xilitla (San Luis Potosí, Central Mexico), located in the southern part of the Tampico-Misantla basin. The sequence consists predominantly of alternating decimeter-thick beds of fossiliferous dark laminated limestone (C-org > 1.0wt%), and light gray, bioturbated limestone (C-org Duque-Botero and Maurrasse, 2005; 2008). These structures are also analogous to microbial mats in present environments, and Devonian deposits (Kremer, 2006). In addition, the laminae at Xilitla include filamentous bacterial structures, as thin and segmented red elements. In some thin sections, filaments appear to be embedded within the crinkly laminae and shreds showing the same pattern of folding, suggestive of biomorphic elements that represent the main producers of the organic matter associated with the laminae. Thus, exceptional bacterial activity characterizes sedimentation during the accumulation of the Agua Nueva Formation. Oxygen-deficient conditions related to the microbial mats were an important element in the mass mortality and preservation of the fish assemblages. Absence of bioturbation, pervasive framboidal pyrite, and the high concentration of organic matter (TOC ranges from 1.2% to 8wt%) in the dark limestones are consistent with persistent recurring dysoxic/anoxic conditions, and the light-gray bioturbated limestones represent relatively well-oxygenated episodes. Planktonic foraminifera (Rotalipora cushmani) and Inoceramu labiatus indicate a time interval from the latest Cenomanian through the earliest Turonian, thus this long interval of severe oxygen deficiency is coeval with Oceanic Anoxic Event 2 (OAE-2). [Duque-Botero and Maurrasse. 2005. Jour. Iberian Geology (31), 85-98; 2008. Cret. Res., 29, 957-964; Kremer. 2006. Acta Palaeontologica Polonica (51, 1), 143-154

  6. Stages of ores formation

    Khasanov, A.Kh.

    1988-01-01

    Deposit formation (especially endogenous) is the complicated, multi-stage and long process. Establishment of deposit formation succession, age-specific correlations of minerals and aggregates have a high importance at solving genetic questions. Studying of minerals correlations and mineral aggregates, succession of their crystallization and other observations let restore the history of deposit formation, pick up in it different on duration and physical and chemical conditions stages

  7. Planet formation in Binaries

    Thebault, Ph.; Haghighipour, N.

    2014-01-01

    Spurred by the discovery of numerous exoplanets in multiple systems, binaries have become in recent years one of the main topics in planet formation research. Numerous studies have investigated to what extent the presence of a stellar companion can affect the planet formation process. Such studies have implications that can reach beyond the sole context of binaries, as they allow to test certain aspects of the planet formation scenario by submitting them to extreme environments. We review her...

  8. Data format translation routines

    Burris, R.D.

    1981-02-01

    To enable the effective connection of several dissimilar computers into a network, modification of the data being passed from one computer to another may become necessary. This document describes a package of routines which permit the translation of data in PDP-8 formats to PDP-11 or DECsystem-10 formats or from PDP-11 format to DECsystem-10 format. Additional routines are described which permit the effective use of the translation routines in the environment of the Fusion Energy Division (FED) network and the Elmo Bumpy Torus (EBT) data base

  9. ENDF/B format

    Khalil, M.A.; Lemmel, H.D.

    1986-09-01

    This document is a brief user's description of the format of ENDF/B. This format, originally designed for the US Evaluated Nuclear Data File, is recommended for international use. This summary is an aid to customers of the IAEA Nuclear Data Section when receiving data retrievals in ENDF/B format. For more detailed information the report BNL-NCS-50496 (ENDF 102) should be consulted. An Appendix to the present document gives a summary of the format differences between ENDF/B-4 and ENDF/B-5. (author)

  10. Exploring Opponent Formats

    Jensen, Mads Møller; Rasmussen, Majken; Grønbæk, Kaj

    2013-01-01

    of how the opponent format and relationships impact a game are almost absent in current research. Thus, this paper aims to elucidate how the perception of a competition differs, depending on the opponent format, by presenting a game mechanic framework. The paper furthermore presents an interactive...... football-training platform, as well as games designed to explore the different opponent formats. The games are qualitatively evaluated to illuminate the qualities of and distinctions between different types of opponent formats, proposed by the framework terminology....

  11. ENDF/B Format

    Khalil, M.A.

    1975-01-01

    This document is a brief user's description of the format of ENDF/B, the evaluated neutron nuclear data library of the US National Nuclear Data Center. This summary is an aid to customers of the IAEA Nuclear Data Section when receiving data retrievals in ENDF/B format. For more detailed information the report BNL-50274 (ENDF-102) should be consulted. (author)

  12. Formation of multiple networks

    Magnani, Matteo; Rossi, Luca

    2013-01-01

    we introduce the first network formation model for multiple networks. Network formation models are among the most popular tools in traditional network studies, because of both their practical and theoretical impact. However, existing models are not sufficient to describe the generation of multiple...

  13. From Sermon Formation to Preacher Formation

    Gaarden, Marianne

    2016-01-01

    today is less about exercising the authority of an office and more about embodying authenticity. I argue that traditional homiletic education can benefit from implementing a learner-centered approach to teaching moving from sermon formation towards preacher formation, in order to develop and train...... preachers. This involves a learning strategy to ministry where theological skills, pastoral competences, and own personality are interwoven. Teaching here means facilitating a room of learning where teacher’s power and control is reduced, allowing the preacher to reflect upon own practice without being...... judged, evaluated, or critiqued. In this paper, I explain how a learner-centered approach to education works in practice and show how pastors experience the teaching method and the congregations’ positive response to their improvements. I shall present the results of a focus-group interview with pastors...

  14. Usage Record Format Recommendation

    Nilsen, J.K.; Muller-Pfeerkorn, R

    2013-01-01

    For resources to be shared, sites must be able to exchange basic accounting and usage data in a common format. This document describes a common format which enables the exchange of basic accounting and usage data from different resources. This record format is intended to facilitate the sharing of usage information, particularly in the area of the accounting of jobs, computing, memory, storage and cloud usage but with a structure that allows an easy extension to other resources. This document describes the Usage Record components both in natural language form and annotated XML. This document does not address how these records should be used, nor does it attempt to dictate the format in which the accounting records are stored. Instead, it denes a common exchange format. Furthermore, nothing is said regarding the communication mechanisms employed to exchange the records, i.e. transport layer, framing, authentication, integrity, etc.

  15. Earth formation porosity log

    Smith, H.D.; Smith, M.P.; Schultz, W.E.

    1977-01-01

    A method for determining the porosity of earth formations in the vicinity of a cased well borehole is described, comprising the steps of: irradiating the earth formations in the vicinity of the cased well borehole with fast neutrons from a source of fast neutrons passed into the borehole; and generating a signal representative of the fast neutron population present in the well borehole at a location in the borehole, the signal is functionally related to the porosity of the earth formations in the vicinity of the borehole

  16. Manuel UNIMARC format bibliographique

    2007-01-01

    This manual is the French translation of the second edition of UNIMARC Manual: bibliographic format published in English in 1994 and completed by 5 updates published from 1996 to 2005. This 5th French edition is composite. It reproduces identically a part of the 4th edition published in 2002 and, for the fields of the format modified in the Update 5, it offers a new more structured presentation. This is a handbook dedicated to French-speaking users of the UNIMARC format for bibliographic descriptions.

  17. Origin Of Black Shale (Marl) Formation Aided By Continuous Volcanism For 10Ma Including Oceanic Anoxic Event, OAE2 (93-93.5 Ma) In The Eagle Ford Formation In South Texas

    Chakrabarty, P.; Basu, A. R.

    2017-12-01

    We report LA-ICPMS U-Pb ages and Hf isotopes of zircons, petrography, major and trace elements and X-ray diffraction (XRD) analyses of whole rock black shales(marls) from volcanic subsurface as well as surface exposure ash beds of the Eagle Ford and Boquillas Formations in South Texas. Zircons from the middle part of the 300ft long Eagle Ford cores yield ages of 93.2±1.66 Ma, 94.13±1.25 Ma and 93.7±1.9 Ma. These ages are consistent with the Cenomanian-Turonian (C-T) age of deposition in three contiguous cores with spatial separation of 140 miles. An approximate 10Ma duration of deposition of volcanic ash and marl, at a rate of 28ft/Ma for the Eagle Ford is suggested from the 85.76 to 95.5 Ma ages. These ages are from the Eagle Ford ash beds, below the Austin Chalk and above the Buda Limestone and cover the Oceanic Anoxic Event 2 at the C-T boundary. Zircons from 7 ash beds in the surface exposures of the Boquillas Formation near Del Rio, yield ages between 84.63 Ma - 90.91 Ma, implying younger than C-T boundary ages for these samples. The mineralogy, major and trace elements of the ash beds suggest their source from nearby arc-derived calc-alkaline volcanism. The ɛHf(T) of the analyzed ash bed zircons yield values between 0 - +8 averaging at +3.5, clearly indicating a mantle component in the host magmas of the zircons. This initial range of ɛHf(T) is similar to arc-volcanism signatures such as the Quaternary andesitic volcanism in Central Mexico. Petrographic analyses of marls away from the visible tuff layer contain phenocrysts of biotite, alkali feldspar and andesitic rock fragments. The whole rock marl with high concentration of some transition metals (V, Zn, Ni, Pb, Mo) and relatively higher MgO and TiO2 contents indicate contemporaneous arc volcanic activity at the time of marl deposition. XRD of subsurface Eagle Ford bulk marl samples from different depths in 4 cores, show volcanogenic clays, such as montmorillonite, vermiculite, dickite and halloysite

  18. Reconsidering formative measurement.

    Howell, Roy D; Breivik, Einar; Wilcox, James B

    2007-06-01

    The relationship between observable responses and the latent constructs they are purported to measure has received considerable attention recently, with particular focus on what has become known as formative measurement. This alternative to reflective measurement in the area of theory-testing research is examined in the context of the potential for interpretational confounding and a construct's ability to function as a point variable within a larger model. Although these issues have been addressed in the traditional reflective measurement context, the authors suggest that they are particularly relevant in evaluating formative measurement models. On the basis of this analysis, the authors conclude that formative measurement is not an equally attractive alternative to reflective measurement and that whenever possible, in developing new measures or choosing among alternative existing measures, researchers should opt for reflective measurement. In addition, the authors provide guidelines for researchers dealing with existing formative measures. Copyright 2007 APA, all rights reserved.

  19. Isothermal Martensite Formation

    Villa, Matteo

    Isothermal (i.e. time dependent) martensite formation in steel was first observed in the 40ies of the XXth century and is still treated as an anomaly in the description of martensite formation which is considered as a-thermal (i.e. independent of time). Recently, the clarification of the mechanism...... of lattice strains provided fundamental information on the state of stress in the material and clarified the role of the strain energy on martensite formation. Electron backscatter diffraction revealed that the microstructure of the material and the morphology of martensite were independent on the cooling...... leading to isothermal kinetics acquired new practical relevance because of the identification of isothermal martensite formation as the most likely process responsible for enhanced performances of sub-zero Celsius treated high carbon steel products. In the present work, different iron based alloys...

  20. Cosmology and galaxy formation

    Rees, M.J.

    1977-01-01

    Implications of the massive halos and ''missing mass'' for galaxy formation are addressed; it is suggested that this mass consists of ''Population III'' stars that formed before the galaxies did. 19 references

  1. Fracturing formations in wells

    Daroza, R A

    1964-05-15

    This well stimulation method comprises introducing through the well bore a low-penetrating, dilatant fluid, and subjecting the fluid to sufficient pressure to produce fractures in the formation. The fluid is permitted to remain in contact with the formation so as to become diluted by the formation fluids, and thereby lose its properties of dilatancy. Also, a penetrating fluid, containing a propping agent suspended therein, in introduced into contact with the fractures at a pressure substantially reduced with respect to that pressure which would have been required, prior to the fracturing operation performed using the low-penetrating dilatant fluid. The propping agent is deposited within the fractures, and thereafter, fluid production is resumed from the fractured formation. (2 claims)

  2. Star formation: Cosmic feast

    Scaringi, Simone

    2017-03-01

    Low-mass stars form through a process known as disk accretion, eating up material that orbits in a disk around them. It turns out that the same mechanism also describes the formation of more massive stars.

  3. PCF File Format.

    Thoreson, Gregory G [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-08-01

    PCF files are binary files designed to contain gamma spectra and neutron count rates from radiation sensors. It is the native format for the GAmma Detector Response and Analysis Software (GADRAS) package [1]. It can contain multiple spectra and information about each spectrum such as energy calibration. This document outlines the format of the file that would allow one to write a computer program to parse and write such files.

  4. Plant Formate Dehydrogenase

    John Markwell

    2005-01-10

    The research in this study identified formate dehydrogenase, an enzyme that plays a metabolic role on the periphery of one-carbon metabolism, has an unusual localization in Arabidopsis thaliana and that the enzyme has an unusual kinetic plasticity. These properties make it possible that this enzyme could be engineered to attempt to engineer plants with an improved photosynthetic efficiency. We have produced transgenic Arabidopsis and tobacco plants with increased expression of the formate dehydrogenase enzyme to initiate further studies.

  5. Blistering and bubble formation

    Roth, J.

    1976-01-01

    Blister formation in metals has been observed during bombardment with inert-gas ions in the energy range between 1 and 2000 keV at doses of about 10 17 to 10 19 cm -2 . The changes in surface topography and the erosion yields were mainly studied in the scanning electron microscope (SEM). Additionally the release of the implanted gas during blister formation was observed. Recently measurements on single crystals were performed determining simultaneously the implantation profile, the total amount of trapped ions, the depth distribution of the induced lattice damage and the thickness of the covers of the blisters. In several stages of the formation process of blisters the implanted layer was observed in the transmission electron microscope (TEM) showing the formation of gas bubbles. Using the results of all these measurements in this review an attempt is made to develop a model of blister formation combining the effects of hydrostatic pressure in the gas bubbles and lateral stress due to volume swelling. (author)

  6. Vascular lumen formation.

    Lammert, Eckhard; Axnick, Jennifer

    2012-04-01

    The vascular system developed early in evolution. It is required in large multicellular organisms for the transport of nutrients, oxygen, and waste products to and from tissues. The vascular system is composed of hollow tubes, which have a high level of complexity in vertebrates. Vasculogenesis describes the de novo formation of blood vessels, e.g., aorta formation in vertebrate embryogenesis. In contrast, angiogenesis is the formation of blood vessels from preexisting ones, e.g., sprouting of intersomitic blood vessels from the aorta. Importantly, the lumen of all blood vessels in vertebrates is lined and formed by endothelial cells. In both vasculogenesis and angiogenesis, lumen formation takes place in a cord of endothelial cells. It involves a complex molecular mechanism composed of endothelial cell repulsion at the cell-cell contacts within the endothelial cell cords, junctional rearrangement, and endothelial cell shape change. As the vascular system also participates in the course of many diseases, such as cancer, stroke, and myocardial infarction, it is important to understand and make use of the molecular mechanisms of blood vessel formation to better understand and manipulate the pathomechanisms involved.

  7. Meningococcal biofilm formation

    Lappann, M.; Haagensen, Janus Anders Juul; Claus, H.

    2006-01-01

    We show that in a standardized in vitro flow system unencapsulated variants of genetically diverse lineages of Neisseria meningitidis formed biofilms, that could be maintained for more than 96 h. Biofilm cells were resistant to penicillin, but not to rifampin or ciprofloxacin. For some strains......, microcolony formation within biofilms was observed. Microcolony formation in strain MC58 depended on a functional copy of the pilE gene encoding the pilus subunit pilin, and was associated with twitching of cells. Nevertheless, unpiliated pilE mutants formed biofilms showing that attachment and accumulation......X alleles was identified among genetically diverse meningococcal strains. PilX alleles differed in their propensity to support autoaggregation of cells in suspension, but not in their ability to support microcolony formation within biofilms in the continuous flow system....

  8. Tritiated ammonia formation

    Heung, L.K.

    1995-01-01

    When nitrogen was selected as the glovebox atmosphere for the Replacement Tritium Facility (RTF) at the Savannah River Site (SRS), a concern was raised as to the possibility of tritiated ammonia formation in the gloveboxes. Experimental data were produced to study the tritiated ammonia formation rate in a tritium and nitrogen mixture. A rate equation that closely simulates the experimental data was developed. This rate equation can be used to calculate the formation of tritiated ammonia from different concentrations of tritium and nitrogen. The reaction of T 2 and N 2 to form NT 3 is a slow process, particularly when the tritium concentration is low. The reaction requires weeks or months to reach radiochemical equilibrium dependent on the concentrations of the reactants. 4 refs., 6 figs., 1 tab

  9. Galaxy formation and evolution

    Mo, Houjun; White, Simon

    2010-01-01

    The rapidly expanding field of galaxy formation lies at the interface between astronomy, particle physics, and cosmology. Covering diverse topics from these disciplines, all of which are needed to understand how galaxies form and evolve, this book is ideal for researchers entering the field. Individual chapters explore the evolution of the Universe as a whole and its particle and radiation content; linear and nonlinear growth of cosmic structure; processes affecting the gaseous and dark matter components of galaxies and their stellar populations; the formation of spiral and elliptical galaxies; central supermassive black holes and the activity associated with them; galaxy interactions; and the intergalactic medium. Emphasizing both observational and theoretical aspects, this book provides a coherent introduction for astronomers, cosmologists, and astroparticle physicists to the broad range of science underlying the formation and evolution of galaxies.

  10. Observsational Planet Formation

    Dong, Ruobing; Zhu, Zhaohuan; Fung, Jeffrey

    2017-06-01

    Planets form in gaseous protoplanetary disks surrounding newborn stars. As such, the most direct way to learn how they form from observations, is to directly watch them forming in disks. In the past, this was very difficult due to a lack of observational capabilities; as such, planet formation was largely a subject of pure theoretical astrophysics. Now, thanks to a fleet of new instruments with unprecedented resolving power that have come online recently, we have just started to unveil features in resolve images of protoplanetary disks, such as gaps and spiral arms, that are most likely associated with embedded (unseen) planets. By comparing observations with theoretical models of planet-disk interactions, the masses and orbits of these still forming planets may be constrained. Such planets may help us to directly test various planet formation models. This marks the onset of a new field — observational planet formation. I will introduce the current status of this field.

  11. Forces in strategy formation

    Steensen, Elmer Fly; Sanchez, Ron

    2008-01-01

    This chapter proposes that organizational strategy formation should be characterized theoretically as a process that is subject to several interacting forces, rather than represented by separate discrete decisionmodels or theoretic perspectives, as is commonly done in the strategic management...... literature. Based on an extensive review of relevant theory and empirical work in strategic decision-making, organizational change theory, cognitive and social psychology, and strategy processes, seven kinds of ''forces'' - rational, imposed, teleological, learning, political, heuristic, and social...... - are identified as interacting in and having significant influence on the strategy formation process. It is further argued that by applying a holistic ''forces-view'' of the significant and interacting influences on strategy formation, we can better understand the dynamics and challenges in managing the process...

  12. Planetesimals and Planet Formation

    Chambers, John

    The first step in the standard model for planet formation is the growth of gravitationally bound bodies called ``planetesimals'' from dust grains in a protoplanetary disk. Currently, we do not know how planetesimals form, how long they take to form, or what their sizes and mechanical properties are. The goal of this proposal is to assess how these uncertainties affect subsequent stages of planetary growth and the kind of planetary systems that form. The work will address three particular questions: (i) Can the properties of small body populations in the modern Solar System constrain the properties of planetesimals? (ii) How do the properties of planetesimals affect the formation of giant planets? (iii) How does the presence of a water ice condensation front (the ``snow line'') in a disk affect planetesimal formation and the later stages of planetary growth? These questions will be examined with computer simulations of planet formation using new computer codes to be developed as part of the proposal. The first question will be addressed using a statistical model for planetesimal coagulation and fragmentation. This code will be merged with the proposer's Mercury N-body integrator code to model the dynamics of large protoplanets in order to address the second question. Finally, a self- consistent model of disk evolution and the radial transport of water ice and vapour will be added to examine the third question. A theoretical understanding of how planets form is one of the key goals of NASA and the Origins of Solar Systems programme. Researchers have carried out many studies designed to address this goal, but the questions of how planetesimals form and how their properties affect planet formation have received relatively little attention. The proposed work will help address these unsolved questions, and place other research in context by assessing the importance of planetesimal origins and properties for planet formation.

  13. Superclusters and galaxy formation

    Einasto, J.; Joeveer, M.; Saar, E.

    1979-01-01

    The spatial distribution of Galaxies and Galaxy congestions in the southern galactic hemisphere is studied. The rich galaxy congestions, containing many elliptic Galaxies and radiogalaxies, are linked with each other by chains of scanty congestions with moderate content of elliptic Galaxies and radiogalaxies. The flat formation, linking the density pikes and the intermediate chains, can reasonably be called supercongestion. In the central region of supercongestions there is a thin layer of Galaxies consisting of only spiral Galaxies. The neighbouring supercongestions touch each other, while the intersupercongestion space contains no Galaxy congestions and almost no Galaxies. It is shown that such a structure was, apparently, formed before the formation of Galaxies

  14. Formation of galaxies

    Szalay, A.S.

    1984-12-01

    The present theories of galaxy formation are reviewed. The relation between peculiar velocities and the correlation function of galaxies points to the possibility that galaxies do not form uniformly everywhere. Scale invariant properties of the cluster-cluster correlations are discussed. Comparing the correlation functions in a dimensionless way, galaxies appear to be stronger clustered, in contrast with the comparison of the dimensional amplitudes of the correlation functions. Theoretical implications of several observations as Lyman-α clouds, correlations of faint galaxies are discussed. None of the present theories of galaxy formation can account for all facts in a natural way. 29 references

  15. The formation of stars

    Stahler, Steven W

    2008-01-01

    This book is a comprehensive treatment of star formation, one of the most active fields of modern astronomy. The reader is guided through the subject in a logically compelling manner. Starting from a general description of stars and interstellar clouds, the authors delineate the earliest phases of stellar evolution. They discuss formation activity not only in the Milky Way, but also in other galaxies, both now and in the remote past. Theory and observation are thoroughly integrated, with the aid of numerous figures and images. In summary, this volume is an invaluable resource, both as a text f

  16. Densities and Kinematic Viscosities for the Systems Benzene + Methyl Formate, Benzene + Ethyl Formate, Benzene + Propyl Formate, and Benzene + Butyl Formate

    Emmerling, Uwe; Rasmussen, Peter

    1998-01-01

    a Redlich-Kister type of expression with temperature-independent parameters and the data for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate with temperature-dependent parameters. The viscosities have furthermore been compared to values predicted by means of the GC......Densities and kinematic viscosities have been measured for the system benzene + methyl formate at 20°C and for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate from 20°C to 50°C. The results for the system benzene + methyl formate have been correlated using...

  17. Barrier cell sheath formation

    Kesner, J.

    1980-04-01

    The solution for electrostatic potential within a simply modeled tandem mirror thermal barrier is seen to exhibit a sheath at each edge of the cell. The formation of the sheath requires ion collisionality and the analysis assmes that the collisional trapping rate into the barrier is considerably slower than the barrier pump rate

  18. Formation of topological defects

    Vachaspati, T.

    1991-01-01

    We consider the formation of point and line topological defects (monopoles and strings) from a general point of view by allowing the probability of formation of a defect to vary. To investigate the statistical properties of the defects at formation we give qualitative arguments that are independent of any particular model in which such defects occur. These arguments are substantiated by numerical results in the case of strings and for monopoles in two dimensions. We find that the network of strings at formation undergoes a transition at a certain critical density below which there are no infinite strings and the closed-string (loop) distribution is exponentially suppressed at large lengths. The results are contrasted with the results of statistical arguments applied to a box of strings in dynamical equilibrium. We argue that if point defects were to form with smaller probability, the distance between monopoles and antimonopoles would decrease while the monopole-to-monopole distance would increase. We find that monopoles are always paired with antimonopoles but the pairing becomes clean only when the number density of defects is small. A similar reasoning would also apply to other defects

  19. The formation of galaxies

    Gunn, J.E.

    1983-01-01

    The presently fashionable ideas for galaxy formation are reviewed briefly, and it is concluded that the standard isothermal heirarchy fits the available data best. A simple infall picture is presented which explains many of the observed properties of disk galaxies. (orig.)

  20. Reconsidering Formative Measurement

    Howell, Roy D.; Breivik, Einar; Wilcox, James B.

    2007-01-01

    The relationship between observable responses and the latent constructs they are purported to measure has received considerable attention recently, with particular focus on what has become known as formative measurement. This alternative to reflective measurement in the area of theory-testing research is examined in the context of the potential…

  1. Chlorination and chloramines formation

    Yee, Lim Fang; Mohd Pauzi Abdullah; Sadia Ata; Abbas Abdullah; Basar IShak; Khairul Nidzham

    2008-01-01

    Chlorination is the most important method of disinfection in Malaysia which aims at ensuring an acceptable and safe drinking water quality. The dosing of chlorine to surface water containing ammonia and nitrogen compounds may form chloramines in the treated water. During this reaction, inorganic and organic chloramines are formed. The recommended maximum acceptable concentration (MAC) for chloramines in drinking water is 3000 μg/L. The production of monochloramine, dichloramine and trichloramine is highly dependent upon pH, contact time and the chlorine to ammonia molar ratio. The purpose of this study is to examine the formation of chloramines that occur upon the chlorination during the treatment process. Chloramines were determined using the N,N-diethyl-p-phenylenediamine (DPD) colorimetric method. The influences of ammonia, pH and chlorine dosage on the chloramines formation were also studied. This paper presents a modeling approach based on regression analysis which is designed to estimate the formation of chloramines. The correlation between the concentration of chloramines and the ammonia, pH and chlorine dosage was examined. In all cases, the quantity of chloramines formed depended linearly upon the amount of chlorine dosage. On the basis of this study it reveals that the concentration of chloramines is a function of chlorine dosage and the ammonia concentration to the chlorination process. PH seems to not significantly affect the formation of chloramines. (author)

  2. Temperature controlled 'void' formation

    Dasgupta, P.; Sharma, B.D.

    1975-01-01

    The nucleation and growth of voids in structural materials during high temperature deformation or irradiation is essentially dependent upon the existence of 'vacancy supersaturation'. The role of temperature dependent diffusion processes in 'void' formation under varying conditions, and the mechanical property changes associated with this microstructure are briefly reviewed. (author)

  3. Triggered star formation

    Palouš, Jan; Ehlerová, Soňa

    2002-01-01

    Roč. 12, - (2002), s. 35-36 ISSN 1405-2059 R&D Projects: GA AV ČR IAA3003705; GA AV ČR KSK1048102 Institutional research plan: CEZ:AV0Z1003909 Keywords : interstellar medium * star formation * HI shells Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  4. Syntactic Formats for Free

    Klin, Bartek; Sobocinski, Pawel

    2003-01-01

    A framework of Plotkin and Turi’s, originally aimed at providing an abstract notion of bi-simulation, is modified to cover other operational equivalences and preorders. Combined with bi-algebraic methods, it yields a technique for the derivation of syntactic formats for transition system specific...

  5. Formation of double layers

    Leung, P.; Wong, A.Y.; Quon, B.H.

    1981-01-01

    Experiments on both stationary and propagating double layers and a related analytical model are described. Stationary double layers were produced in a multiple plasma device, in which an electron drift current was present. An investigation of the plasma parameters for the stable double layer condition is described. The particle distribution in the stable double layer establishes a potential profile, which creates electron and ion beams that excite plasma instabilities. The measured characteristics of the instabilities are consistent with the existence of the double layer. Propagating double layers are formed when the initial electron drift current is large. Ths slopes of the transition region increase as they propagate. A physical model for the formation of a double layer in the experimental device is described. This model explains the formation of the low potential region on the basis of the space charge. This space charge is created by the electron drift current. The model also accounts for the role of ions in double layer formation and explains the formation of moving double layers. (Auth.)

  6. COMPETENCYTHE FORMATION FOR LIFE

    Milagros Mederos-Piñeiro

    2016-07-01

    Full Text Available The formation of life competences is the result of a quality education that prepares students to meet the challenges of a fast moving world where equality and equal opportunities should constitute premises of education; training them is a challenge teachers to assume new generations contribute actively to a better world. In Cuba are important research on the formation of communication competences and self-regulated learning in primary school. The paper shows the result of an investigation that provides a methodology for the formation of life competences in primary school education, used as an essential pathway research activity. The methodological approach of research has a quantitative approach and an explanatory scope to establish and make sense of understanding the causal relationship between the direction of research activity and training of life competences. Theoretical, empirical and mathematical-statistical, for characterizing the initial state, processing of results and analysis: research methods are used. The application of the methodology for the formation of life competences makes teachers lead the teaching-learning process with a research and transforming teaching concept, where the school is the protagonist of their learning and causes changes in their performances, which are evident in the formed competences related to effective and affective communication; the solution of problems related to life; the use of means in obtaining the knowledge and the expression of a behavior consistent with school and social demands. The effectiveness of the methodology confirms that there is a causal relationship between the direction of research activity by teachers and the formation of life competences in school.

  7. Medusae Fossae Formation

    2002-01-01

    (Released 10 April 2002) The Science This THEMIS visible image was acquired near 7o S, 172o W (188o E) and shows a remarkable martian geologic deposit known as the Medusae Fossae Formation. This Formation, seen here as the raised plateau in the upper two-thirds of the image, is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. In this region the deposit has been heavily eroded by the wind to produce a series of linear ridges called yardangs. These parallel ridges point in direction of the prevailing winds that carved them, and demonstrate the power of martian winds to sculpt the dry landscape of Mars. The Medusae Fossae Formation has been completely stripped from the surface in the lower third of the image, revealing a harder layer below that is more resistant to wind erosion. The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Several ancient craters that were once completely buried by this deposit are being exposed, or exhumed, as the overlying Medusae Formation is removed. Very few impact craters are visible on this Formation, indicating that the surface seen today is relatively young, and that the processes of erosion are likely to be actively occurring. The Story Medusa of Greek mythology fame, the name-giver to this region, had snaky locks of hair that could turn a person to stone. Wild and unruly, this monster of the underworld could certainly wreak havoc on the world of the human imagination. As scary as she was, Medusa would have no advantage over the fierce, masterful winds blowing across Mars, which once carved the streaky, terrain at the top of this image. Wild and whipping, these winds have slowly eroded away the 'topsoil,' revealing ancient craters and other surface features they once covered. The loosely cemented particles of this 'topsoil' are likely made up of dust

  8. The format of things

    Jørnø, Rasmus Leth

    this conception is identified as “the Format of Things.” The format is embedded in our everyday thinking. In relation to design,it is found in the name taken by the design community, that is human-computer interaction (HCI), and it is mirrored in the desktop metaphor, wherein information is conceived...... available. It consists of philosophical considerations on matters of relevance for the design of interfaces. It takes the position that the graphical user interfaces of computers (the Desktop Metaphor or Windows, Icons, Menus, Pointers [‘WIMP’]) that ordinarily come to mind for most people are cognates......The development of novel interfaces is one of the most important current design challenges for the intellectual, cultural and cognitive evolution of human imagination and knowledge work. Unfortunately, the thinking surrounding this design challenge is heavily mired in conceptions that harbor...

  9. Plasma formation in TBR

    Del Bosco, E.

    1981-01-01

    In this work are presented and discussed results of the formation and equilibrium of the plasma current in TBR, a small tokamak, designed and contructed at the Instituto de Fisica of Universidade de Sao Paulo. The measured breakdown curves for H 2 , A and He are compared with the predictions of a simple model with reasonable agreement. The influence of stray magnetic fields in the plasma formation is investigated and conditions are chosen to facilitate the breakdown. The time profile of loop voltage and plasma current for shots with plasma equilibrium are shown. A comparison is made between experimental results and analytical-numerical model for tokamaks discharges with ohmic heating. Reasonable agreement is obtained when Z, effective atomic number, is assumed as a parameter. (Author) [pt

  10. Formation of coronal cavities

    An, C.H.; Suess, S.T.; Tandberg-Hanssen, E.; Steinolfson, R.S.

    1986-01-01

    A theoretical study of the formation of a coronal cavity and its relation to a quiescent prominence is presented. It is argued that the formation of a cavity is initiated by the condensation of plasma which is trapped by the coronal magnetic field in a closed streamer and which then flows down to the chromosphere along the field lines due to lack of stable magnetic support against gravity. The existence of a coronal cavity depends on the coronal magnetic field strength; with low strength, the plasma density is not high enough for condensation to occur. Furthermore, we suggest that prominence and cavity material is supplied from the chromospheric level. Whether a coronal cavity and a prominence coexist depends on the magnetic field configuration; a prominence requires stable magnetic support

  11. Understanding Alliance Formation Patterns

    2015-12-01

    military, transportation, and communications technologies, which caused every place in the world to be politically significant. Second, “divisions of power...test a similar claim about the association between distance and dyadic alliance formation. In their first model, in which they use the complete data...1885 to 1990] are positively related to dyadic trade levels, and that their non- defense-pact counterparts are not significantly related to trade in

  12. Alkali metal hydride formation

    1976-01-01

    The present invention relates to a method of producing alkali metal hydrides by absorbing hydrogen gas under pressure into a mixture of lower alkyl mono amines and alkali metal alkyl amides selected from sodium and potassium amides formed from said amines. The present invention also includes purification of a mixture of the amines and amides which contain impurities, such as is used as a catalytic exchange liquid in the enrichment of deuterium, involving the formation of the alkali metal hydride

  13. Formation of TRAPPIST-1

    Ormel, C. W.; Liu, B.; Schoonenberg, D.

    2017-09-01

    We present a model for the formation of the recently-discovered TRAPPIST-1 planetary system. In our scenario planets form in the interior regions, by accretion of mm to cm-size particles (pebbles) that drifted from the outer disk. This scenario has several advantages: it connects to the observation that disks are made up of pebbles, it is efficient, it explains why the TRAPPIST-1 planets are ˜Earth mass, and it provides a rationale for the system's architecture.

  14. THE ALLIANCE FORMATION PROCESS

    Whipple, Judith M.; Frankel, Robert

    1998-01-01

    While interest in developing strategic alliances within the food system continues to increase, there remains considerable risk when firms adopt such a cooperative strategy. The risk is due in part to the lack of concrete guidelines that illustrate the steps or stages of alliance development and the important strategic and operational decisions required at each stage. The existence of such guidelines would facilitate alliance formation and enable managers and researchers to better understand a...

  15. Complexity and formative experiences

    Roque Strieder

    2017-12-01

    Full Text Available The contemporaneity is characterized by instability and diversity calling into question certainties and truths proposed in modernity. We recognize that the reality of things and phenomena become effective as a set of events, interactions, retroactions and chances. This different frame extends the need for revision of the epistemological foundations that sustain educational practices and give them sense. The complex thinking is an alternative option for acting as a counterpoint to classical science and its reductionist logic and knowledge compartmentalization, as well as to answer to contemporary epistemological and educational challenges. It aims to associate different areas and forms of knowledge, without, however merge them, distinguishing without separating the several disciplines and instances of the realities. This study, in theoretical references, highlights the relevance of complex approaches to support formative experiences because also able to produce complexities in reflections about educational issues. We conclude that formative possibilities from complexity potentialize the resignification of human’s conception and the understanding of its singularity in interdependence; The understanding that pedagogical and educational activities is a constant interrogation about the possibilities of knowing the knowledge and reframe learning, far beyond knowing its functions and utilitarian purposes; and, as a formative possibility, places us on the trail of responsibility, not as something eventual, but present and indicative of freedom to choose to stay or go beyond.

  16. Terrestrial planet formation.

    Righter, K; O'Brien, D P

    2011-11-29

    Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (~10(6) y), followed by planetesimals to embryos (lunar to Mars-sized objects; few 10(6) y), and finally embryos to planets (10(7)-10(8) y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids.

  17. Fracturing of subterranean formations

    Kiel, O.M.; Kidwell, A.L.

    1968-03-19

    This method of propping fractured formations results in high conductivities. In the method, certain naturally occurring crystals are used as propping agents. Suitable crystals include garnet, corundum, zircon, rutile, high-temperature quartz, and other minerals which have Moh's hardness values of about 6 or greater and weather out as individual crystals of about 40 mesh or larger. These are said to result in permeabilities significantly higher than those obtained with ordinary quartz sand, metallic shot, glass beads, plastic particles, walnut hulls, or similar materials. (10 claims)

  18. Situated Formative Feedback

    Lukassen, Niels Bech; Wahl, Christian; Sorensen, Elsebeth Korsgaard

    refer to this type of feedback as, Situated Formative Feedback (SFF). As a basis for exploring, identifying and discussing relevant aspects of SFF the paper analyses qualitative data from a Moodle dialogue. Data are embedded in the qualitative analytic program Nvivo and are analysed with a system...... theoretical textual analysis method. Asynchronous written dialogue from an online master’s course at Aalborg University forms the empirical basis of the study. The findings suggests in general that students play an essential role in SFF and that students and educators are equal in the COP, but holds different...

  19. Superclusters and galaxy formation

    Einasto, J; Joeveer, M; Saar, E [Tartu Astrophysical Observatory, Toravere, Estonia (USSR)

    1980-01-03

    A study of the structure of superclusters in the Southern galactic hemisphere using Zwicky clusters as principal tracers of the large-scale structure of the Universe is reported. The data presented suggest that the formation of galaxies was a two stage process involving larger spatial dimensions than earlier workers have postulated. In the first stage proto-superclusters and big holes had to form from the non-dissipative dark matter while in the second hot gas, by cooling and settling down into the potential wells caused by dark matter, will form galaxies and clusters of galaxies.

  20. Urbanization and Slum Formation

    Phua, Kai Hong

    2007-01-01

    The formation of slums need not be inevitable with rapid urbanization. Such an argument appears to be contradicted by evidence of large slum populations in a large number of developing countries and particularly in rapidly urbanizing regions like Asia. The evidence discussed suggests that city authorities faced with rapid urban development lack the capacity to cope with the diverse demands for infrastructural provision to meet economic and social needs. Not only are strategic planning and intervention major issues in agenda to manage rapid urbanization, but city governments are not effectively linking the economic development trajectory to implications for urban growth and, hence, housing needs. In the following discussion, a case study is presented in support of the argument that city governments have to first recognize and then act to establish the link that is crucial between economic development, urban growth, and housing. This is the agendum that has been largely neglected by city and national governments that have been narrowly focused on economic growth with the consequent proliferation of slum formation as a housing solution. PMID:17387618

  1. Formation of planetary systems

    Brahic, A.

    1982-01-01

    It seemed appropriate to devote the 1980 School to the origin of the solar system and more particularly to the formation of planetary systems (dynamic accretion processes, small bodies, planetary rings, etc...) and to the physics and chemistry of planetary interiors, surface and atmospheres (physical and chemical constraints associated with their formation). This Summer School enabled both young researchers and hard-nosed scientists, gathered together in idyllic surroundings, to hold numerous discussions, to lay the foundations for future cooperation, to acquire an excellent basic understanding, and to make many useful contacts. This volume reflects the lectures and presentations that were delivered in this Summer School setting. It is aimed at both advanced students and research workers wishing to specialize in planetology. Every effort has been made to give an overview of the basic knowledge required in order to gain a better understanding of the origin of the solar system. Each article has been revised by one or two referees whom I would like to thank for their assistance. Between the end of the School in August 1980 and the publication of this volume in 1982, the Voyager probes have returned a wealth of useful information. Some preliminary results have been included for completeness

  2. A Mesoproterozoic iron formation

    Canfield, Donald E.; Zhang, Shuichang; Wang, Huajian; Wang, Xiaomei; Zhao, Wenzhi; Su, Jin; Bjerrum, Christian J.; Haxen, Emma R.; Hammarlund, Emma U.

    2018-04-01

    We describe a 1,400 million-year old (Ma) iron formation (IF) from the Xiamaling Formation of the North China Craton. We estimate this IF to have contained at least 520 gigatons of authigenic Fe, comparable in size to many IFs of the Paleoproterozoic Era (2,500–1,600 Ma). Therefore, substantial IFs formed in the time window between 1,800 and 800 Ma, where they are generally believed to have been absent. The Xiamaling IF is of exceptionally low thermal maturity, allowing the preservation of organic biomarkers and an unprecedented view of iron-cycle dynamics during IF emplacement. We identify tetramethyl aryl isoprenoid (TMAI) biomarkers linked to anoxygenic photosynthetic bacteria and thus phototrophic Fe oxidation. Although we cannot rule out other pathways of Fe oxidation, iron and organic matter likely deposited to the sediment in a ratio similar to that expected for anoxygenic photosynthesis. Fe reduction was likely a dominant and efficient pathway of organic matter mineralization, as indicated by organic matter maturation by Rock Eval pyrolysis combined with carbon isotope analyses: Indeed, Fe reduction was seemingly as efficient as oxic respiration. Overall, this Mesoproterozoic-aged IF shows many similarities to Archean-aged (>2,500 Ma) banded IFs (BIFs), but with an exceptional state of preservation, allowing an unprecedented exploration of Fe-cycle dynamics in IF deposition.

  3. Endocytosis and Enamel Formation

    Cong-Dat Pham

    2017-07-01

    Full Text Available Enamel formation requires consecutive stages of development to achieve its characteristic extreme mineral hardness. Mineralization depends on the initial presence then removal of degraded enamel proteins from the matrix via endocytosis. The ameloblast membrane resides at the interface between matrix and cell. Enamel formation is controlled by ameloblasts that produce enamel in stages to build the enamel layer (secretory stage and to reach final mineralization (maturation stage. Each stage has specific functional requirements for the ameloblasts. Ameloblasts adopt different cell morphologies during each stage. Protein trafficking including the secretion and endocytosis of enamel proteins is a fundamental task in ameloblasts. The sites of internalization of enamel proteins on the ameloblast membrane are specific for every stage. In this review, an overview of endocytosis and trafficking of vesicles in ameloblasts is presented. The pathways for internalization and routing of vesicles are described. Endocytosis is proposed as a mechanism to remove debris of degraded enamel protein and to obtain feedback from the matrix on the status of the maturing enamel.

  4. U-Pb zircon constraints on the age of the Cretaceous Mata Amarilla Formation, Southern Patagonia, Argentina: its relationship with the evolution of the Austral Basin Edades U-Pb en circones de la Formación Mata Amarilla (Cretácico, Patagonia Austral, Argentina: su relación con la evoluci��n de la Cuenca Austral

    Augusto N Varela

    2012-09-01

    Full Text Available Despite the abundant fossil content of the Mata Amarilla Formation (Southern Patagonia, Santa Cruz Province, Argentina, its age has always generated a considerable number of questions and debates. The chronological data provided by invertebrates, dinosaurs, fish, turtles, plesiosaurs and fossil flora are contradictory. In this work, twenty U-Pb spot analyses by laser ablation were carried out on the outer parts of the zoned zircon crystals from a tuff layer of the middle section of the Mata Amarilla Formation, yielding a U-Pb concordia age of 96.23±0.71 Ma, which corresponds to the middle Cenomanian. The deposition of the lower section of the Mata Amarilla Formation marks the onset of the foreland stage of the Austral Basin (also known as Magallanes Basin; this transition is characterized by the west-east shift of the depositional systems, which is consistent with the progradation of the Cretaceous fold-and-thrust belt. Thus, the onset of the foreland stage could have occurred between the upper Albian and lower Cenomanian, as the underlying Piedra Clavada Formation is lower Albian in age. On comparing the data obtained with information from the Última Esperanza Province in Chile, it can be suggested that the initiation of the closure of the Rocas Verdes Marginal Basin occurred simultaneously.A pesar del abundante contenido fosilífero de la Formación Mata Amarilla (Patagonia Austral, Provincia de Santa Cruz, Argentina, siempre se generaron abundantes dudas y debates acerca de cuál es la edad de esta formación. Los datos cronológicos aportados por los invertebrados, los dinosaurios, peces, tortugas, plesiosaurios y flora fósil son dispares. En el presente trabajo se obtuvo una edad U-Pb concordia por la metodología de ablación láser aplicada a 20 puntos de la parte externa de circones zonados provenientes de un nivel tobáceo hallado en la sección media de la Formación Mata Amarilla, lo cual arrojó una edad de 96,23±0,71 Ma, que

  5. Star Formation in Irregular Galaxies.

    Hunter, Deidre; Wolff, Sidney

    1985-01-01

    Examines mechanisms of how stars are formed in irregular galaxies. Formation in giant irregular galaxies, formation in dwarf irregular galaxies, and comparisons with larger star-forming regions found in spiral galaxies are considered separately. (JN)

  6. Standard exercise report format (SERF)

    Anon.

    1995-01-01

    This talk summarizes the reasons for the development of draft SERF the Standard Exercise Report Format used for reporting the results of emergency preparedness exercises, and gives a summary of the format and rational behind it

  7. Restoring formation after leaching process

    Barrett, R.B.

    1983-01-01

    A method of restoring a formation which had uranium and other mineral values extracted by an alkaline lixiviant comprises introducing a source of phosphate in an amount sufficient to lower the level of soluble uranium compounds below that previously existing in the formation by the formation of insoluble uranium phosphate compounds

  8. Formative Research in Educational Media.

    Hodapp, Timothy

    This paper distinguishes between basic research, applied research, and evaluation. Evaluation is broken down into two types: summative and formative. The limitations of formative research are presented, followed by a discussion of the value of the formative researcher participating in the product planning process. The types of data which formative…

  9. Designing for informed group formation

    Nicolajsen, Hanne Westh; Juel Jacobsen, Alice; Riis, Marianne

    2012-01-01

    A new design ―project preparation‖ preparing for the group formation in problem based project work is proposed and investigated. The main problem is to overcome group formation based on existing relations. The hypothesis is that theme development and group formation are somewhat counterproductive...

  10. Determinants for gallstone formation

    Shabanzadeh, Daniel Monsted; Sorensen, Lars Tue; Jørgensen, Torben

    2016-01-01

    . Gallstone incidence was assessed through repeated ultrasound examinations. Body mass index (BMI), blood pressure, self-rated health, lifestyle variables, blood lipids, and use of female sex hormones were measured at the baseline examination. Statistical analyses included logistic regression. Based...... re-examination were followed-up completely (mean 11.6 years, N = 2848). The overall cumulative incidence of gallstones was 0.60% per year. Independent positive determinants for incident gallstones were age, female sex, non-high density lipoprotein (non-HDL) cholesterol, and gallbladder polyps...... associations were found for blood pressure, smoking, alcohol consumption, HDL cholesterol, or triglycerides in meta-analyses. Conclusions: Age, female sex, BMI, non-HDL cholesterol, and polyps are independent determinants for gallstone formation. Incident gallstones and the metabolic syndrome share common risk...

  11. Standardizing exchange formats

    Lemmel, H.D.; Schmidt, J.J.

    1992-01-01

    An international network of co-operating data centres is described who maintain identical data bases which are simultaneously updated by an agreed data exchange procedure. The agreement covers ''data exchange formats'' which are compatible to the centres' internal data storage and retrieval systems which remain different, optimized at each centre to the available computer facilities and to the needs of the data users. Essential condition for the data exchange is an agreement on common procedures for the data exchange is an agreement on common procedures for the data compilation, including critical data analysis and validation. The systems described (''EXFOR'', ''ENDF'', ''CINDA'') are used for ''nuclear reaction data'', but the principles used for data compilation and exchange should be valid also for other data types. (author). 24 refs, 4 figs

  12. Recipes for planet formation

    Meyer, Michael R.

    2009-11-01

    Anyone who has ever used baking soda instead of baking powder when trying to make a cake knows a simple truth: ingredients matter. The same is true for planet formation. Planets are made from the materials that coalesce in a rotating disk around young stars - essentially the "leftovers" from when the stars themselves formed through the gravitational collapse of rotating clouds of gas and dust. The planet-making disk should therefore initially have the same gas-to-dust ratio as the interstellar medium: about 100 to 1, by mass. Similarly, it seems logical that the elemental composition of the disk should match that of the star, reflecting the initial conditions at that particular spot in the galaxy.

  13. Formation of Service Ecosystems

    Jonas, Julia M.; Sörhammar, David; Satzger, Gerhard

    – i.e. the “birth phase” (Moore, 2009) of a service ecosystem. This paper, therefore, aims to explore how the somewhat “magic” processes of service ecosystem formation that are being taken for granted actually occur. Methodology/Approach: Building on a review of core elements in the definitions...... for Harvard students) or value proposition (share messages, photos, videos, etc. with friends). Processes of configuring actors, resources, and value propositions are influenced by the structural embeddedness of the service ecosystem (e.g., regional infrastructure, existing networks of actors, or resource...... availability) as well as guided by the actors’ own and shared institutions (e.g., rules, norms,and beliefs).We contextualize each starting point with illustrative cases and analyze the service ecosystem configuration process: “Axoon/Trumpf” (initiated by resources), “JOSEPHS – the service manufactory...

  14. Symbol Formation Reconsidered

    Wagoner, Brady

    2013-01-01

    them vis-à-vis other research at Clark and in American psychology more generally. The second two articles analyse Werner and Kaplan’s notions of ‘distancing’ and ‘physiognomic metaphor’, showing their roots in naturphilosophie and comparing them with contemporary theories. The last four articles apply......Werner and Kaplan’s Symbol formation was published 50 years ago but its insights have yet to be adequately explored by psychology and other social sciences. This special issue aims to revisit this seminal work in search of concepts to work on key issues facing us today. This introductory article...... begins with a brief outline and contextualization of the book as well as of the articles that this special issue comprises. The first two articles were written by contributors who were part of the Werner era at Clark University. They explore the key concepts of the organismic and development, and situate...

  15. Formation of small sparks

    Barreto, E.; Jurenka, H.; Reynolds, S.I.

    1977-01-01

    The formation of a small incendiary spark at atmospheric pressure is identified with the transition from a weakly to a strongly ionized plasma. It is shown that initial gaseous ionization produced by avalanches and/or streamers always creates a high-temperature ideal electron gas that can shield the applied voltage difference and reduce ionization in the volume of the gas. The electron gas is collision dominated but able to maintain its high temperature, for times long compared to discharge events, through long-range Coulomb forces. In fact, electrons in the weakly ionized plasma constitute a collisionless independent fluid with a thermodynamic state that can be affected directly by field or density changes. Accordingly, with metal electrodes, cathode spot emission is always associated with the transition to a strongly ionized plasma. Neutral heating can be accomplished in two different ways. Effective dispersal of the electrons from the cathode leads to electron heating dominated by diffusion effects. Conversely, a fast rate of emission or rapid field changes can produce nonlinear wave propagation. It is shown that solitary waves are possible, and it is suggested that some spark transitions are associated with shock waves in the collisionless electron gas. In either the diffuse or nonlinear regime, neutral gas heating is controlled by collisions of ions with isotropic thermal electrons. This interaction is always subsequent to changes in state of the electron gas population. The basic results obtained should apply to all sparks

  16. Large Format Radiographic Imaging

    Rohrer, J. S.; Stewart, Lacey; Wilke, M. D.; King, N. S.; Baker A, S.; Lewis, Wilfred

    1999-01-01

    Radiographic imaging continues to be a key diagnostic in many areas at Los Alamos National Laboratory (LANL). Radiographic recording systems have taken on many form, from high repetition-rate, gated systems to film recording and storage phosphors. Some systems are designed for synchronization to an accelerator while others may be single shot or may record a frame sequence in a dynamic radiography experiment. While film recording remains a reliable standby in the radiographic community, there is growing interest in investigating electronic recording for many applications. The advantages of real time access to remote data acquisition are highly attractive. Cooled CCD camera systems are capable of providing greater sensitivity with improved signal-to-noise ratio. This paper begins with a review of performance characteristics of the Bechtel Nevada large format imaging system, a gated system capable of viewing scintillators up to 300 mm in diameter. We then examine configuration alternatives in lens coupled and fiber optically coupled electro-optical recording systems. Areas of investigation include tradeoffs between fiber optic and lens coupling, methods of image magnification, and spectral matching from scintillator to CCD camera. Key performance features discussed include field of view, resolution, sensitivity, dynamic range, and system noise characteristics

  17. What Determines Star Formation Rates?

    Evans, Neal John

    2017-06-01

    The relations between star formation and gas have received renewed attention. We combine studies on scales ranging from local (within 0.5 kpc) to distant galaxies to assess what factors contribute to star formation. These include studies of star forming regions in the Milky Way, the LMC, nearby galaxies with spatially resolved star formation, and integrated galaxy studies. We test whether total molecular gas or dense gas provides the best predictor of star formation rate. The star formation ``efficiency," defined as star formation rate divided by mass, spreads over a large range when the mass refers to molecular gas; the standard deviation of the log of the efficiency decreases by a factor of three when the mass of relatively dense molecular gas is used rather than the mass of all the molecular gas. We suggest ways to further develop the concept of "dense gas" to incorporate other factors, such as turbulence.

  18. Designing for informed group formation

    Nicolajsen, Hanne Westh; Juel Jacobsen, Alice; Riis, Marianne

    2012-01-01

    A new design ―project preparation‖ preparing for the group formation in problem based project work is proposed and investigated. The main problem is to overcome group formation based on existing relations. The hypothesis is that theme development and group formation are somewhat counterproductive....... Following research based design methodology an experiment separating the two was initiated.This was to provide for more openness and creativity in contrast to a design in which existing relations seem predominant....

  19. Light meromyosin paracrystal formation.

    Chowrashi, P K; Pepe, F A

    1977-07-01

    STUDIES OF PARACRYSTAL FORMATION BY COLUMN PURIFIED LIGHT MEROMYOSIN (LMM) PREPARED IN A VARIETY OF WAYS LED TO THE FOLLOWING CONCLUSIONS: (a) different portions of the myosin rod may be coded for different stagger relationships. This was concluded from observations that paracrystals with different axial repeat periodicities could be obtained either with LMM framents of different lengths prepared with the same enzyme, or with LMM fragments of identical lengths but prepared with different enzymes. (b) Paracrystals with a 14-nm axial repeat periodicity are most likely formed by the aggregation of sheets with a 44-nm axial repeat within the sheets which are staggered by 14 nm. All of the axial repeat patterns expected from one sheet or aggregates of more than one sheet, on this basis, were observed in the same electron micrograph. (c) C-protein binding probably occurs preferentially to LMM molecules related in some specific way. This was concluded from the observation that the same axial repeat pattern was obtained in paracrystals formed from different LMM preparations in the presence of C-protein, regardless of differences in the axial repeat obtained in the absence of C-protein. (d) Nucleic acid is responsible for the 43-nm axial repeat patterns observed in paracrystals formed by the ethanol-resistant fraction of LMM. In the absence of nuclei acid, paracrystals with a 14nm axial repeat are obtained. (e) The 43-nm axial repeat pattern observed with the ethanol-resistant fraction of LMM is different for LMM preparations obtained by trypsin and papain digestions.

  20. Pattern formation during electropolishing

    Yuzhakov, V.V.; Chang, H.; Miller, A.E.

    1997-01-01

    Using atomic force microscopy, we find that the surface morphology of a dissolving aluminum anode in a commercial electropolishing electrolyte can exhibit both highly regular and randomly packed stripe and hexagonal patterns with amplitudes of about 5 nm and wavelengths of 100 nm. The driving instability of this pattern formation phenomenon is proposed to be the preferential adsorption of polar or polarizable organic molecules on surface ridges where the contorted double layer produces a higher electric potential gradient. The enhanced relative coverage shields the anode and induces a smaller dissolution rate at the ridges. The instability is balanced by surface diffusion of the adsorbate to yield a length scale of 4π(D s /k d ) 1/2 , where D s is the surface diffusivity and k d is the desorption coefficient of the adsorbate, which correlates well with the measured wavelength. A long-wavelength expansion of the double-layer field yields an interface evolution equation that reproduces all of the observed patterns. In particular, bifurcation analysis and numerical simulation yield a single voltage-dependent dimensionless parameter ξ that measures a balance between smoothing of adsorbate concentration by electric-field-dependent surface diffusion and fluctuation due to interfacial curvature and stretching. Randomly oriented stripes are favored at large ξ (low voltage), while random hills dominate at small ξ (high voltage) with perfectly periodic stripes and hexagonal hill patterns within a small window near ξ=1. These predictions are in qualitative and quantitative agreement with our measurements. copyright 1997 The American Physical Society

  1. Formative assessment : Enriching teaching and learning with formative assesment

    van Diggelen, M.R.; Morgan, C.M.; Funk, M.; Bruns, M.

    2016-01-01

    Formative assessment is a valuable aspect in teaching and learning, and is proven to be an e ective learning method. There is evidence that adding formative assessment to your teaching increases students’ learning results (Black and William, 1998), but in practice many of the possibilities are left

  2. Formation of interstellar anions

    Senent, Maria Luisa

    2012-05-01

    Formation of interstellar anions: M.L. Senent. The recent detection of negative charged species in the ISM1 has instigated enthusiasm for anions in the astrophysical community2. Many of these species are new and entail characterization. How they are formed in astrophysical sources is a question of major relevance. The anion presence in ISM was first predicted theoretically on the basis of electron affinities and on the negative linear chain molecular stabilities. Although very early, they were considered in astrochemical models3-4, their discovery is so recent because their abundances seem to be relatively low. These have to be understood in terms of molecular stabilities, reaction probabilities and radiative and collisional excitations. Then, we present our theoretical work on even carbon chains type Cn and CnH (n=2,4,6) focused to the understanding of anion abundances. We use highly correlated ab initio methods. We performed spectroscopic studies of various isomers that can play important roles as intermediates5-8. In previous papers9-10, we compared C2H and C2H- collisional rates responsible for observed line intensities. Actually, we study hydrogen attachment (Cn +H → CnH and Cn- +H → CnH-) and associative detachment processes (Cn- +H → CnH +e-) for 2, 4 and 6 carbon atom chains11. [1] M.C.McCarthy, C.A.Gottlieb, H.Gupta, P.Thaddeus, Astrophys.J, 652, L141 (2006) [2] V.M.Bierbaum, J.Cernicharo, R.Bachiller, eds., 2011, pp 383-389. [3] A. Dalgarno, R.A. Mc Cray, Astrophys.J,, 181, 95 (1973) [4] E. Herbst E., Nature, 289, 656 (1981); [5] H.Massó, M.L.Senent, P.Rosmus, M.Hochlaf, J.Chem.Phys., 124, 234304 (2006) [6] M.L.Senent, M.Hochlaf, Astrophys. J. , 708, 1452(2010) [7] H.Massó, M.L.Senent, J.Phys.Chem.A, 113, 12404 (2009) [8] D. Hammoutene, M.Hochlaf, M.L.Senent, submitted. [9] A. Spielfiedel, N. Feautrier, F. Najar, D. ben Abdallah, F. Dayou, M.L. Senent, F. Lique, Mon.Not.R.Astron.Soc., 421, 1891 (2012) [10] F.Dumouchel, A, Spielfieldel , M

  3. Satellite formation flying relative dynamics, formation design, fuel optimal maneuvers and formation maintenance

    Wang, Danwei; Poh, Eng Kee

    2017-01-01

    This book systematically describes the concepts and principles for multi-satellite relative motion, passive and near passive formation designs, trajectory planning and control for fuel optimal formation maneuvers, and formation flying maintenance control design. As such, it provides a sound foundation for researchers and engineers in this field to develop further theories and pursue their implementations. Though satellite formation flying is widely considered to be a major advance in space technology, there are few systematic treatments of the topic in the literature. Addressing that gap, the book offers a valuable resource for academics, researchers, postgraduate students and practitioners in the field of satellite science and engineering.

  4. Portable File Format (PFF) specifications

    Dolan, Daniel H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-02-01

    Created at Sandia National Laboratories, the Portable File Format (PFF) allows binary data transfer across computer platforms. Although this capability is supported by many other formats, PFF files are still in use at Sandia, particularly in pulsed power research. This report provides detailed PFF specifications for accessing data without relying on legacy code.

  5. Professional Development through Formative Evaluation

    Nsibande, Rejoice; Garraway, James

    2011-01-01

    Formative evaluation and its associated methodology of reflection on practice are used extensively in academic staff development. In reflecting on formative evaluation processes in both more traditional and newer programmes conducted at a university of technology, a number of variables reported in the literature were observed to have influenced…

  6. Star formation in the multiverse

    Bousso, Raphael; Leichenauer, Stefan

    2009-01-01

    We develop a simple semianalytic model of the star formation rate as a function of time. We estimate the star formation rate for a wide range of values of the cosmological constant, spatial curvature, and primordial density contrast. Our model can predict such parameters in the multiverse, if the underlying theory landscape and the cosmological measure are known.

  7. A format for phylogenetic placements.

    Frederick A Matsen

    Full Text Available We have developed a unified format for phylogenetic placements, that is, mappings of environmental sequence data (e.g., short reads into a phylogenetic tree. We are motivated to do so by the growing number of tools for computing and post-processing phylogenetic placements, and the lack of an established standard for storing them. The format is lightweight, versatile, extensible, and is based on the JSON format, which can be parsed by most modern programming languages. Our format is already implemented in several tools for computing and post-processing parsimony- and likelihood-based phylogenetic placements and has worked well in practice. We believe that establishing a standard format for analyzing read placements at this early stage will lead to a more efficient development of powerful and portable post-analysis tools for the growing applications of phylogenetic placement.

  8. Uranium logging in earth formations

    Givens, W.W.

    1979-01-01

    A technique is provided for assaying the formations surrounding a borehole for uranium. A borehole logging tool cyclically irradiates the formations with neutrons and responds to neutron fluxes produced during the period of time that prompt neutrons are being produced by the neutron fission of uranium in the formations. A borehole calibration tool employs a steady-state (continuous output) neutron source, firstly, to produce a response to neutron fluxes in models having known concentrations of uranium and, secondly, to to produce a response to neutron fluxes in the formations surrounding the borehole. The neutron flux responses of the borehole calibration tool in both the model and the formations surrounding the borehole are utilized to correct the neutron flux response of the borehole logging tool for the effects of epithermal/thermal neutron moderation, scattering, and absorption within the borehole itself

  9. Geological factors of deposit formation

    Grushevoj, G.V.

    1980-01-01

    Geologic factors of hydrogenic uranium deposit formation are considered. Structural, formation and lithological-facies factors of deposit formation, connected with zones of stratal oxidation, are characterized. Peculiarities of deposit localization, connected with orogenic structures of Mesozoic and lenozoic age, are described. It is noted that deposits of anagenous group are widely spread in Paleozoic formations, infiltration uranium deposits are localized mainly in Cenozoic sediments, while uranium mineralization both anagenous and infiltration groups are widely developed in Mesozoic sediments. Anagenous deposits were formed in non-oxygen situation, their age varies from 200 to 55 mln years. Infiltration deposit formation is determined by asymmetric oxidation zonation, their age varies from 10 - 40 mln years to dozens of thousand years [ru

  10. Process for fracturing underground formations

    Kiel, O M

    1974-01-25

    This invention concerns a process for fracturing underground formations and has as one object the mixing of viscous compositions. Through a borehole, a fluid is injected into the formation. This fluid contains a complex prepared by the reaction of an aliphatic quaternary ammonium compound with a water-soluble compound chosen from monosaccharides, disaccharides, trisaccharides, polysaccharides, and synthetic hydroxylated polymers with long chains. These complexes are formed at temperatures between 20/sup 0/ and 205/sup 0/C. The process also includes production of formation fluid into the borehole.

  11. Free-format RPG IV

    Martin, Jim

    2013-01-01

    This how-to guide offers a concise and thorough introduction to the increased productivity, better readability, and easier program maintenance that comes with the free-format style of programming in RPG IV. Although free-format information is available in IBM manuals, it is not separated from everything else, thereby requiring hours of tedious research to track down the information needed. This book provides everything one needs to know to write RPG IV in the free-format style, and author Jim Martin not only teaches rules and syntax but also explains how this new style of coding has the pot

  12. AGN feedback in galaxy formation

    Antonuccio-Delogu, Vincenzo

    2010-01-01

    During the past decade, convincing evidence has been accumulated concerning the effect of active galactic nuclei (AGN) activity on the internal and external environment of their host galaxies. Featuring contributions from well-respected researchers in the field, and bringing together work by specialists in both galaxy formation and AGN, this volume addresses a number of key questions about AGN feedback in the context of galaxy formation. The topics covered include downsizing and star-formation time scales in massive elliptical galaxies, the connection between the epochs of supermassive black h

  13. DNA methylation and memory formation.

    Day, Jeremy J; Sweatt, J David

    2010-11-01

    Memory formation and storage require long-lasting changes in memory-related neuronal circuits. Recent evidence indicates that DNA methylation may serve as a contributing mechanism in memory formation and storage. These emerging findings suggest a role for an epigenetic mechanism in learning and long-term memory maintenance and raise apparent conundrums and questions. For example, it is unclear how DNA methylation might be reversed during the formation of a memory, how changes in DNA methylation alter neuronal function to promote memory formation, and how DNA methylation patterns differ between neuronal structures to enable both consolidation and storage of memories. Here we evaluate the existing evidence supporting a role for DNA methylation in memory, discuss how DNA methylation may affect genetic and neuronal function to contribute to behavior, propose several future directions for the emerging subfield of neuroepigenetics, and begin to address some of the broader implications of this work.

  14. Robust Decentralized Formation Flight Control

    Zhao Weihua

    2011-01-01

    Full Text Available Motivated by the idea of multiplexed model predictive control (MMPC, this paper introduces a new framework for unmanned aerial vehicles (UAVs formation flight and coordination. Formulated using MMPC approach, the whole centralized formation flight system is considered as a linear periodic system with control inputs of each UAV subsystem as its periodic inputs. Divided into decentralized subsystems, the whole formation flight system is guaranteed stable if proper terminal cost and terminal constraints are added to each decentralized MPC formulation of the UAV subsystem. The decentralized robust MPC formulation for each UAV subsystem with bounded input disturbances and model uncertainties is also presented. Furthermore, an obstacle avoidance control scheme for any shape and size of obstacles, including the nonapriorily known ones, is integrated under the unified MPC framework. The results from simulations demonstrate that the proposed framework can successfully achieve robust collision-free formation flights.

  15. The multifaceted planetesimal formation process

    Johansen, Anders; Blum, Jürgen; Tanaka, Hidekazu

    2013-01-01

    Accumulation of dust and ice particles into planetesimals is an important step in the planet formation process. Planetesimals are the seeds of both terrestrial planets and the solid cores of gas and ice giants forming by core accretion. Left-over planetesimals in the form of asteroids, trans...... for planetesimal formation where particle growth starts unaided by self-gravity but later proceeds inside gravitationally collapsing pebble clumps to form planetesimals with a wide range of sizes....

  16. Chain formation of metal atoms

    Bahn, Sune Rastad; Jacobsen, Karsten Wedel

    2001-01-01

    The possibility of formation of single-atomic chains by manipulation of nanocontacts is studied for a selection of metals (Ni, Pd, Pt, Cu, Ag, Au). Molecular dynamics simulations show that the tendency for chain formation is strongest for Au and Pt. Density functional theory calculations indicate...... that the metals which form chains exhibit pronounced many-atom interactions with strong bonding in low coordinated systems....

  17. Cosmic strings and galaxy formation

    Bertschinger, Edmund

    1989-01-01

    The cosmogonical model proposed by Zel'dovich and Vilenkin (1981), in which superconducting cosmic strings act as seeds for the origin of structure in the universe, is discussed, summarizing the results of recent theoretical investigations. Consideration is given to the formation of cosmic strings, the microscopic structure of strings, gravitational effects, cosmic string evolution, and the formation of galaxies and large-scale structure. Simulation results are presented in graphs, and several outstanding issues are listed and briefly characterized.

  18. An Adaptable Seismic Data Format

    Krischer, Lion; Smith, James; Lei, Wenjie; Lefebvre, Matthieu; Ruan, Youyi; de Andrade, Elliott Sales; Podhorszki, Norbert; Bozdağ, Ebru; Tromp, Jeroen

    2016-11-01

    We present ASDF, the Adaptable Seismic Data Format, a modern and practical data format for all branches of seismology and beyond. The growing volume of freely available data coupled with ever expanding computational power opens avenues to tackle larger and more complex problems. Current bottlenecks include inefficient resource usage and insufficient data organization. Properly scaling a problem requires the resolution of both these challenges, and existing data formats are no longer up to the task. ASDF stores any number of synthetic, processed or unaltered waveforms in a single file. A key improvement compared to existing formats is the inclusion of comprehensive meta information, such as event or station information, in the same file. Additionally, it is also usable for any non-waveform data, for example, cross-correlations, adjoint sources or receiver functions. Last but not least, full provenance information can be stored alongside each item of data, thereby enhancing reproducibility and accountability. Any data set in our proposed format is self-describing and can be readily exchanged with others, facilitating collaboration. The utilization of the HDF5 container format grants efficient and parallel I/O operations, integrated compression algorithms and check sums to guard against data corruption. To not reinvent the wheel and to build upon past developments, we use existing standards like QuakeML, StationXML, W3C PROV and HDF5 wherever feasible. Usability and tool support are crucial for any new format to gain acceptance. We developed mature C/Fortran and Python based APIs coupling ASDF to the widely used SPECFEM3D_GLOBE and ObsPy toolkits.

  19. Review of nutrition labeling formats.

    Geiger, C J; Wyse, B W; Parent, C R; Hansen, R G

    1991-07-01

    This article examines nutrition labeling history as well as the findings of nine research studies of nutrition labeling formats. Nutrition labeling regulations were announced in 1973 and have been periodically amended since then. In response to requests from consumers and health care professionals for revision of the labeling system, the Food and Drug Administration initiated a three-phase plan for reform of nutrition labeling in 1990. President Bush signed the Nutrition Labeling and Education Act in November 1990. Literature analysis revealed that only nine studies with an experimental design have focused on nutrition labeling since 1971. Four were conducted before 1975, which was the year that nutrition labeling was officially implemented, two were conducted in 1980, and three were conducted after 1986. Only two of the nine studies supported the traditional label format mandated by the Code of Federal Regulations, and one study partially supported it. Four of the nine studies that evaluated graphic presentations of nutrition information found that consumer comprehension of nutrition information was improved with a graphic format for nutrition labeling: three studies supported the use of bar graphs and one study supported the use of a pie chart. Full disclosure (ie, complete nutrient and ingredient labeling) was preferred by consumers in two of the three studies that examined this variable. The third study supported three types of information disclosure dependent upon socioeconomic class. In those studies that tested graphics, a bar graph format was significantly preferred and showed better consumer comprehension than the traditional format.

  20. Automation of Tabular Application Formation

    S. V. Zykin

    2013-01-01

    Full Text Available The paper considers automation problems of the interface formation between a table and a relational database. The task description is formalized and the description of the existing approaches to formation of data representations on an example of widely widespread CASE-tools is submitted. The definition of intermediate data representation as a ”join table” is offered, which is used for maintenance of correctness of data representation formation, and also is necessary for direct and inverse data transformations. On the basis of lossless join property and realized dependencies, the concept and a way of context formation of the application and restrictions is introduced. The considered material is further used for constructing an inverse data transformation from tabular presentation into a relational one. On the basis of relationships properties on a database scheme, the partial order on the relations is established, and the restriction of acyclic databases schemes is introduced. The received results are further used at the analysis of principles of formation of inverse data transformation, and the basic details of such a transformation algorithm are considered.

  1. Formative assessment: a student perspective.

    Hill, D A; Guinea, A I; McCarthy, W H

    1994-09-01

    An educator's view would be that formative assessment has an important role in the learning process. This study was carried out to obtain a student perspective of the place of formative assessment in the curriculum. Final-year medical students at Royal Prince Alfred Hospital took part in four teaching sessions, each structured to integrate teaching with assessment. Three assessment methods were used; the group objective structured clinical examination (G-OSCE), structured short answer (SSA) questions and a pre/post-test multiple choice questionnaire (MCQ). Teaching sessions were conducted on the subject areas of traumatology, the 'acute abdomen', arterial disorders and cancer. Fifty-five students, representing 83% of those who took part in the programme, responded to a questionnaire where they were asked to rate (on a 5-point Likert scale) their response to general questions about formative assessment and 13 specific questions concerning the comparative value of the three assessment modalities. Eighty-nine per cent of respondents felt that formative assessment should be incorporated into the teaching process. The SSA assessment was regarded as the preferred modality to reinforce previous teaching and test problem-solving skills. The MCQ was the least favoured assessment method. The effect size variable between the total scores for the SSA and MCQ was 0.64. The variable between G-OSCE and SSA/MCQ was 0.26 and 0.33 respectively. Formative assessment is a potentially powerful method to direct learning behaviour. Students should have input into the methods used.

  2. The Physics of Planetesimal Formation

    Simon, Jacob; Armitage, Philip; Youdin, Andrew; Li, Rixin

    2015-12-01

    Planetesimals are the precursors to planets, and understanding their formation is an essential step towards developing a complete theory of planet formation. For small solid particles (e.g., dust grains) to coagulate into planetesimals, however, requires that these particles grow beyond centimeter sizes; with traditional coagulation physics, this is very difficult. The streaming instability, which is a clumping process akin to the pile-up of cars in a traffic jam, generates sufficiently high solid densities that the mutual gravity between the clumped particles eventually causes their collapse towards planetesimal mass and size scales. Exploring this transition from dust grains to planetesimals is still in its infancy but is extremely important if we want to understand the basics of planet formation. Here, I present a series of high resolution, first principles numerical simulations of potoplanetary disk gas and dust to study the clumping of particles via the streaming instability and the subsequent collapse towards planetesimals. These simulations have been employed to characterize the planetesimal population as a function of radius in protoplanetary disks. The results of these simulations will be crucial for planet formation models to correctly explain the formation and configuration of solar systems.

  3. Exoplanets Detection, Formation, Properties, Habitability

    Mason, John W

    2008-01-01

    This edited, multi-author volume will be an invaluable introduction and reference to all key aspects in the field of exoplanet research. The reviews cover: Detection methods and properties of known exoplanets, Detection of extrasolar planets by gravitational microlensing. The formation and evolution of terrestrial planets in protoplanetary and debris disks. The brown dwarf-exoplanet connection. Formation, migration mechanisms and properties of hot Jupiters. Dynamics of multiple exoplanet systems. Doppler exoplanet surveys. Searching for exoplanets in the stellar graveyard. Formation and habitability of extra solar planets in multiple star systems. Exoplanet habitats and the possibilities for life. Moons of exoplanets: habitats for life. Contributing authors: •Rory Barnes •David P. Bennett •Jian Ge •Nader Haghighipour •Patrick Irwin •Hugh Jones •Victoria Meadows •Stanimir Metchev •I. Neill Reid •George Rieke •Caleb Scharf •Steinn Sigurdsson

  4. Modularity in New Market Formation

    Sanchez, Ron; Hang, Chang Chieh

    2017-01-01

    In this paper we appraise the ways in which use of closed-system proprietary product architectures versus open-system modular product architectures is likely to influence the dynamics and trajectory of new product market formation. We compare the evolutions of new markets in China for gas......-powered two-wheeled vehicles (G2WVs) based (initially) on closed-system proprietary architectures and for electric-powered two-wheeled vehicles (E2WVs) based on open-system modular architectures. We draw on this comparison to suggest ways in which the use of the two different kinds of architectures...... as the basis for new kinds of products may result in very different patterns and speeds of new market formation. We then suggest some key implications of the different dynamics of market formation associated with open-system modular architectures for both the competence-based strategic management (CBSM...

  5. Cosmic strings and galaxy formation

    Bertschinger, E.

    1989-01-01

    Cosmic strings have become increasingly popular candidates as seeds for the formation of structure in the universe. This scenario, remains a serious cosmogonical model despite close scrutiny. In constrast, magnetic monopoles and domain walls - relic topological defects as are cosmic strings - are disastrous for cosmology if they are left over from the early universe. The production of heavy cosmic strings is speculative, as it depends on the details of ultrahigh energy physics. Fortunately, speculation about cosmic strings is not entirely idle because, if they exist and are heavy enough to seed galaxy formation, cosmic strings can be detected astronomically. Failure to detect cosmic strings would impose some constraints on grand unified theories (GUTs); their discovery would have exciting consequences for high energy physics and cosmology. This article reviews the basic physics of nonsuperconducting cosmic strings, highlighting the field theory aspects, and provides a progress report on calculations of structure formation with cosmic strings

  6. 'TV Format Protection through Marketing Strategies?'

    Singh, Sukhpreet

    2008-01-01

    Commercially successful programme ideas are often imitated or adapted. Television formats, in particular, are routinely copied. Starting from radio formats in the 1950s to game shows and reality programme formats of today, producers have accused others of “stealing”. Although formats constitute one of the most important exports for British TV producers, there is still no certainty about the legal protection of TV formats from copycat versions. Since TV formats fail to fall neatly within the d...

  7. Regulation of Reactionary Dentine Formation.

    Neves, V C M; Sharpe, P T

    2018-04-01

    During the treatment of dental caries that has not penetrated the tooth pulp, maintenance of as much unaffected dentine as possible is a major goal during the physical removal of decayed mineral. Damage to dentine leads to release of fossilized factors (transforming growth factor-β [TGF-β] and bone morphogenic protein [BMP]) in the dentine that are believed to stimulate odontoblasts to secrete new "tertiary" dentine (reactionary dentine). This is formed on the pulpal surface of existing dentine and rethickens the dentine. We have previously shown that activation of Wnt/β-catenin signaling is pivotal for tooth repair in exposed pulp injury, and the pathway can be activated by small-molecule GSK-3 antagonists, resulting in enhanced reparative dentine formation. Here, we use a nonexposed pulp injury model to investigate the mechanisms of reactionary dentine formation in vivo, using small molecules to modulate the Wnt/β-catenin, TGF-β, and BMP pathways. We found that a local increase of Wnt activation at the injury site enhances reactionary dentine secretion. In addition, inhibition of TGF-β, BMP, or Wnt pathways does not impede reactionary dentine formation, although inhibition of TGF-β and/or BMP signaling does result in more disorganized, nontubular reactionary dentine. This suggests that Wnt/β-catenin signaling plays no major role in the formation of reactionary dentine, but in common with reparative dentine formation, exogenous elevation of Wnt/β-catenin signaling can enhance tertiary dentine formation. Release of latent TGF-β or BMPs from dentine is not required for the deposition of mineral to form reactionary dentine but does play a role in its organization.

  8. Radionuclide migration in geological formations

    Barbreau, A.; Heremans, R.; Skytte Jensen, B.

    1980-01-01

    Radioactive waste disposal into geological formation is based on the capacity of rocks to confine radioactivity for a long period of time. Radionuclide migration from the repository to the environment depends on different mechanisms and phenomena whose two main ones are groundwater flow and the retention and ion-exchange property of rocks. Many studies are underway presently in EEC countries concerning hydrodynamic characteristics of deep geological formations as well as in radionuclide retention capacity and modelling. Important results have already been achieved which show the complexity of some phenomena and further studies shall principally be developed taking into account real conditions of the repository and its environment

  9. Pattern formations and oscillatory phenomena

    Kinoshita, Shuichi

    2013-01-01

    Patterns and their formations appear throughout nature, and are studied to analyze different problems in science and make predictions across a wide range of disciplines including biology, physics, mathematics, chemistry, material science, and nanoscience. With the emergence of nanoscience and the ability for researchers and scientists to study living systems at the biological level, pattern formation research has become even more essential. This book is an accessible first of its kind guide for scientists, researchers, engineers, and students who require a general introduction to thi

  10. The formation of ice sails

    Fowler, A. C.; Mayer, C.

    2017-11-01

    Debris-covered glaciers are prone to the formation of a number of supraglacial geomorphological features, and generally speaking, their upper surfaces are far from level surfaces. Some of these features are due to radiation screening or enhancing properties of the debris cover, but theoretical explanations of the consequent surface forms are in their infancy. In this paper we consider a theoretical model for the formation of "ice sails", which are regularly spaced bare ice features which are found on debris-covered glaciers in the Karakoram.

  11. The Hunt for Pristine Cretaceous Astronomical Rhythms at Demerara Rise (Cenomanian-Coniacian)

    Ma, C.; Meyers, S. R.

    2014-12-01

    Rhythmic Upper Cretaceous strata from Demerara Rise (ODP leg 207) preserve a strong astronomical signature, and this attribute has facilitated the development of continuous astrochronologies to refine the geologic time scale and calibrate Late Cretaceous biogeochemical events. While the mere identification of astronomical rhythms is a crucial first step in many deep-time paleoceanographic investigations, accurate evaluation of often subtle amplitude and frequency modulations are required to: (1) robustly constrain the linkage between climate and sedimentation, and (2) evaluate the plausibility of different theoretical astrodynamical models. The availability of a wide range of geophysical, lithologic and geochemical data from multiple sites drilled at Demerara Rise - when coupled with recent innovations in the statistical analysis of cyclostratigraphic data - provides an opportunity to hunt for the most pristine record of Cretaceous astronomical rhythms at a tropical Atlantic location. To do so, a statistical metric is developed to evaluate the "internal" consistency of hypothesized astronomical rhythms observed in each data set, particularly with regard to the expected astronomical amplitude modulations. In this presentation, we focus on how the new analysis yields refinements to the existing astrochronologies, provides constraints on the linkages between climate and sedimentation (including the deposition of organic carbon-rich sediments at Demerara Rise), and allows a quantitative evaluation of the continuity of deposition across sites at multiple temporal scales.

  12. Market formation and market selection

    van Raalte, C.L.J.P.

    1996-01-01

    The organization of markets is an important field of inquiry in modern economic theory. This monograph analyzes models which consider the formation and selection of markets. In these models, markets are organized by middlemen and used by traders. In Part I of the monograph, coalitions of middlemen

  13. A Model of Partnership Formation

    Talman, A.J.J.; Yang, Z.F.

    2008-01-01

    This paper presents a model of partnership formation. A set of agents wants to conduct some business or other activities. Agents may act alone or seek a partner for cooperation and need in the latter case to consider with whom to cooperate and how to share the profit in a collaborative and

  14. The Road to Galaxy Formation

    Keel, William C

    2007-01-01

    The formation of galaxies is one of the greatest puzzles in astronomy, the solution is shrouded in the depths of space and time, but has profound implications for the universe we observe today. The book discusses the beginnings of the process from cosmological observations and calculations, considers the broad features of galaxies that we need to explain and what we know of their later history. The author compares the competing theories for galaxy formation and considers the progress expected from new generations of powerful telescopes both on earth and in space. In this second edition the author has retained the observationally-based approach of the first edition, a feature which was particularly well-reviewed: Writing in Nature, Carlton Baugh noted in February 2003 that “It is refreshing, in a market dominated by theorists, to come across a book on galaxy formation written from an observational perspective. The Road to Galaxy Formation should prove to be a handy primer on observations for graduate student...

  15. Analysis of Disulfide Bond Formation

    Braakman, Ineke; Lamriben, Lydia; van Zadelhoff, Guus; Hebert, Daniel N.

    2017-01-01

    In this unit, protocols are provided for detection of disulfide bond formation in cultures of intact cells and in an in vitro translation system containing isolated microsomes or semi-permeabilized cells. First, the newly synthesized protein of interest is biosynthetically labeled with radioactive

  16. A model of partnership formation

    Talman, A.J.J.; Yang, Z.F.

    2011-01-01

    This paper presents a model of partnership formation. A number of agents want to conduct some business or other activities. Agents may act alone or seek a partner for cooperation and need in the latter case to consider with whom to cooperate and how to share the profit in a collaborative and

  17. Is All Formative Influence Immoral?

    Tillson, John

    2018-01-01

    Is it true that all formative influence is unethical, and that we ought to avoid influencing children (and indeed anyone at all)? There are more or less defensible versions of this doctrine, and we shall follow some of the strands of argument that lead to this conclusion. It seems that in maintaining that all influence is immoral, one commits…

  18. Exciton Formation in Disordered Semiconductors

    Klochikhin, A.; Reznitsky, A.; Permogorov, S.

    1999-01-01

    Stationary luminescence spectra of disordered solid solutions can be accounted by the model of localized excitons. Detailed analysis of the long time decay kinetics of luminescence shows that exciton formation in these systems is in great extent due to the bimolecular reaction of separated carrie...

  19. Auditory and phonetic category formation

    Goudbeek, Martijn; Cutler, A.; Smits, R.; Swingley, D.; Cohen, Henri; Lefebvre, Claire

    2017-01-01

    Among infants' first steps in language acquisition is learning the relevant contrasts of the language-specific phonemic repertoire. This learning is viewed as the formation of categories in a multidimensional psychophysical space. Research in the visual modality has shown that for adults, some kinds

  20. Facial Prototype Formation in Children.

    Inn, Donald; And Others

    This study examined memory representation as it is exhibited in young children's formation of facial prototypes. In the first part of the study, researchers constructed images of faces using an Identikit that provided the features of hair, eyes, mouth, nose, and chin. Images were varied systematically. A series of these images, called exemplar…

  1. Mantle dynamics following supercontinent formation

    Heron, Philip J.

    This thesis presents mantle convection numerical simulations of supercontinent formation. Approximately 300 million years ago, through the large-scale subduction of oceanic sea floor, continental material amalgamated to form the supercontinent Pangea. For 100 million years after its formation, Pangea remained relatively stationary, and subduction of oceanic material featured on its margins. The present-day location of the continents is due to the rifting apart of Pangea, with supercontinent dispersal being characterized by increased volcanic activity linked to the generation of deep mantle plumes. The work presented here investigates the thermal evolution of mantle dynamics (e.g., mantle temperatures and sub-continental plumes) following the formation of a supercontinent. Specifically, continental insulation and continental margin subduction are analyzed. Continental material, as compared to oceanic material, inhibits heat flow from the mantle. Previous numerical simulations have shown that the formation of a stationary supercontinent would elevate sub-continental mantle temperatures due to the effect of continental insulation, leading to the break-up of the continent. By modelling a vigorously convecting mantle that features thermally and mechanically distinct continental and oceanic plates, this study shows the effect of continental insulation on the mantle to be minimal. However, the formation of a supercontinent results in sub-continental plume formation due to the re-positioning of subduction zones to the margins of the continent. Accordingly, it is demonstrated that continental insulation is not a significant factor in producing sub-supercontinent plumes but that subduction patterns control the location and timing of upwelling formation. A theme throughout the thesis is an inquiry into why geodynamic studies would produce different results. Mantle viscosity, Rayleigh number, continental size, continental insulation, and oceanic plate boundary evolution are

  2. Inside-out planet formation

    Chatterjee, Sourav; Tan, Jonathan C.

    2014-01-01

    The compact multi-transiting planet systems discovered by Kepler challenge planet formation theories. Formation in situ from disks with radial mass surface density, Σ, profiles similar to the minimum mass solar nebula but boosted in normalization by factors ≳ 10 has been suggested. We propose that a more natural way to create these planets in the inner disk is formation sequentially from the inside-out via creation of successive gravitationally unstable rings fed from a continuous stream of small (∼cm-m size) 'pebbles', drifting inward via gas drag. Pebbles collect at the pressure maximum associated with the transition from a magnetorotational instability (MRI)-inactive ('dead zone') region to an inner MRI-active zone. A pebble ring builds up until it either becomes gravitationally unstable to form an ∼1 M ⊕ planet directly or induces gradual planet formation via core accretion. The planet may undergo Type I migration into the active region, allowing a new pebble ring and planet to form behind it. Alternatively, if migration is inefficient, the planet may continue to accrete from the disk until it becomes massive enough to isolate itself from the accretion flow. A variety of densities may result depending on the relative importance of residual gas accretion as the planet approaches its isolation mass. The process can repeat with a new pebble ring gathering at the new pressure maximum associated with the retreating dead-zone boundary. Our simple analytical model for this scenario of inside-out planet formation yields planetary masses, relative mass scalings with orbital radius, and minimum orbital separations consistent with those seen by Kepler. It provides an explanation of how massive planets can form with tightly packed and well-aligned system architectures, starting from typical protoplanetary disk properties.

  3. Dioxin formation from waste incineration.

    Shibamoto, Takayuki; Yasuhara, Akio; Katami, Takeo

    2007-01-01

    There has been great concern about dioxins-polychlorinated dibenzo dioxins (PCDDs), polychlorinated dibenzo furans (PCDFs), and polychlorinated biphenyls (PCBs)-causing contamination in the environment because the adverse effects of these chemicals on human health have been known for many years. Possible dioxin-contamination has received much attention recently not only by environmental scientists but also by the public, because dioxins are known to be formed during the combustion of industrial and domestic wastes and to escape into the environment via exhaust gases from incinerators. Consequently, there is a pressing need to investigate the formation mechanisms or reaction pathways of these chlorinated chemicals to be able to devise ways to reduce their environmental contamination. A well-controlled small-scale incinerator was used for the experiments in the core references of this review. These articles report the investigation of dioxin formation from the combustion of various waste-simulated samples, including different kinds of paper, various kinds of wood, fallen leaves, food samples, polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene chloride, polyethylene tetraphthalate (PET), and various kinds of plastic products. These samples were also incinerated with inorganic chlorides (NaCl, KCl, CuCI2, MgCl2, MnCl2, FeCl2, CoCl2, fly ash, and seawater) or organic chlorides (PVC, chlordane, and pentachlorophenol) to investigate the role of chlorine content and/or the presence of different metals in dioxin formation. Some samples, such as newspapers, were burned after they were impregnated with NaCl or PVC, as well as being cocombusted with chlorides. The roles of incineration conditions, including chamber temperatures, O2 concentrations, and CO concentrations, in dioxin formation were also investigated. Dioxins (PCDDs, PCDFs, and coplanar-PCBs) formed in the exhaust gases from a controlled small-scale incinerator, where experimental waste

  4. Consensus formation on coevolving networks: groups' formation and structure

    Kozma, Balazs; Barrat, Alain

    2008-01-01

    We study the effect of adaptivity on a social model of opinion dynamics and consensus formation. We analyse how the adaptivity of the network of contacts between agents to the underlying social dynamics affects the size and topological properties of groups and the convergence time to the stable final state. We find that, while on static networks these properties are determined by percolation phenomena, on adaptive networks the rewiring process leads to different behaviors: adaptive rewiring fosters group formation by enhancing communication between agents of similar opinion, though it also makes possible the division of clusters. We show how the convergence time is determined by the characteristic time of link rearrangement. We finally investigate how the adaptivity yields nontrivial correlations between the internal topology and the size of the groups of agreeing agents

  5. Stratigraphy and dissolution of the Rustler Formation

    Bachman, G.O.

    1987-01-01

    This report describes the physical stratigraphy of the Rustler Formation, because the Waste Isolation Pilot Plant will be constructed in salt beds that underlie this formation. Described are subdivisions of the formations, the major karst features, and a proposed method for the formation of Nash Draw. 2 refs., 2 figs

  6. Towards an improved lithostratigraphic subdivision of the chalk group in the Netherlands North Sea area - A seismic stratigraphic approach

    Molen, A.S. van der; Wong, Th.E.

    2007-01-01

    In the Netherlands North Sea area, the Chalk Group has thus far been subdivided into the Cenomanian Texel Formation, the Turonian to Maastrichtian Ommelanden Formation and the Danian Ekofisk Formation. This paper describes the attempt to arrive at a more detailed lithostratigraphic subdivision for

  7. Towards an improved lithostratigraphic subdivision of the Chalk Group in the Netherlands North Sea area – A seismic stratigraphic approach

    Molen, A.S. van der; Wong, Th.E.

    In the Netherlands North Sea area, the Chalk Group has thus far been subdivided into the Cenomanian Texel Formation, the Turonian to MaastrichtianOmmelanden Formation and the Danian Ekofisk Formation. This paper describes the attempt to arrive at a more detailed lithostratigraphicsubdivision for

  8. Track formation. Principles and applications

    Monnin, M.

    1978-01-01

    The principles and technical aspects of track formation in insulating solids are first described. The characteristics of dialectic track detection are discussed from the technical point of view: the nature of the detectors, the chemical treatment, the sensitivity and the environmental conditions of use. The applications are reviewed. The principle of each type of applied research is described and then the applications are listed. When used as a detector, nuclear tracks can provide valuable information in a number of fields: element content determination and wrapping, imaging, radiation dosimetry, environmental studies, technological uses and miscellaneous other applications. The track-formation process can also be used for making well-defined holes; this method allows other applications which are also described. Finally, some possible future applications are mentioned. (author)

  9. Nuclear processing during star formation

    Newman, M.J.

    1978-01-01

    A preliminary survey was conducted of the thermonuclear energy release expected during star formation. The destruction of primordial deuterium provides substantial amounts of energy at surprisingly low temperatures, and must be considered in any meaningful treatment of star formation carried to stages in which the internal temperature exceeds a few hundred thousand degrees. Significant energy generation from consumption of initial lithium requires higher temperatures, of the order of a few million degrees. Depletion of primordial beryllium and boron may never provide an important energy source. The approach to equilibrium of the carbon--nitrogen cycle is dominant at temperatures approaching those characteristic of the central regions of main sequence stars. The present calculation should serve as a useful guide in choosing those nuclear processes to be included in a more detailed study. 8 figures, 2 tables

  10. Coevolutionary modeling in network formation

    Al-Shyoukh, Ibrahim

    2014-12-03

    Network coevolution, the process of network topology evolution in feedback with dynamical processes over the network nodes, is a common feature of many engineered and natural networks. In such settings, the change in network topology occurs at a comparable time scale to nodal dynamics. Coevolutionary modeling offers the possibility to better understand how and why network structures emerge. For example, social networks can exhibit a variety of structures, ranging from almost uniform to scale-free degree distributions. While current models of network formation can reproduce these structures, coevolutionary modeling can offer a better understanding of the underlying dynamics. This paper presents an overview of recent work on coevolutionary models of network formation, with an emphasis on the following three settings: (i) dynamic flow of benefits and costs, (ii) transient link establishment costs, and (iii) latent preferential attachment.

  11. Star Formation in Dusty Quasars

    Lumsden, Stuart; Croom, Scott

    2012-04-01

    Quasar mode feedback is thought to be a crucial ingredient in galaxy formation for luminous merging and star-bursting systems at high redshift. The energy from the active nucleus should cause significant gas outflows, reducing the available free gas reservoir for future star formation. It is currently unknown which observational state best corresponds to the stage at which this "blowout" should occur. We intend to test one possible source population for this transition phase, by studying the molecular gas content in a small, statistically complete sample of 3 K-band selected reddened quasars from the AUS survey. All lie in the redshift range 2

  12. Method for consolidating incompetent formations

    Pavlich, J.P.; Calvert, D.G.

    1965-02-23

    An incompetent formation is consolidated and left permeable by first injecting a solidifiable liquid resin, and following this by an organic liquid to set the resin. The liquid resin used may be 3 (glycidyloxy) propyl trimethoxysilane in sufficient concentration to considerably increase the compressive strength of the consolidated zone. The silane may be used in a ratio of between 0.5 and 5% of the total volume of the liquid resin. The liquid resin used may be a phenol-formaldehyde condensation product dispersed in an aliphatic alcohol with from 1 to 4 carbon atoms. The liquid resin used may be an epoxy containing a hardener. The resin may be displaced into the formation by a liquid hydrocarbon. (5 claims)

  13. Othering, identity formation and agency

    Sune Qvotrup Jensen

    2011-10-01

    Full Text Available The article examines the potentials of the concept of othering to describe identity formation among ethnic minorities. First, it outlines the history of the concept, its contemporary use, as well as some criticisms. Then it is argued that young ethnic minority men in Denmark are subject to intersectional othering, which contains elements of exoticist fascination of the other. On the basis of ethnographic material, it is analysed how young marginalized ethnic minority men react to othering. Two types of reactions are illustrated: 1 capitalization on being positioned as the other, and 2 refusing to occupy the position of the other by disidentification and claims to normality. Finally, it is argued that the concept of othering is well suited for understanding the power structures as well as the historic symbolic meanings conditioning such identity formation, but problematic in terms of agency.

  14. Coevolutionary modeling in network formation

    Al-Shyoukh, Ibrahim; Chasparis, Georgios; Shamma, Jeff S.

    2014-01-01

    Network coevolution, the process of network topology evolution in feedback with dynamical processes over the network nodes, is a common feature of many engineered and natural networks. In such settings, the change in network topology occurs at a comparable time scale to nodal dynamics. Coevolutionary modeling offers the possibility to better understand how and why network structures emerge. For example, social networks can exhibit a variety of structures, ranging from almost uniform to scale-free degree distributions. While current models of network formation can reproduce these structures, coevolutionary modeling can offer a better understanding of the underlying dynamics. This paper presents an overview of recent work on coevolutionary models of network formation, with an emphasis on the following three settings: (i) dynamic flow of benefits and costs, (ii) transient link establishment costs, and (iii) latent preferential attachment.

  15. THE BLACK HOLE FORMATION PROBABILITY

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D., E-mail: dclausen@tapir.caltech.edu [TAPIR, Walter Burke Institute for Theoretical Physics, California Institute of Technology, Mailcode 350-17, Pasadena, CA 91125 (United States)

    2015-02-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P {sub BH}(M {sub ZAMS}). Although we find that it is difficult to derive a unique P {sub BH}(M {sub ZAMS}) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P {sub BH}(M {sub ZAMS}) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P {sub BH}(M {sub ZAMS}) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  16. A study on frost formation

    青木, 和夫

    1986-01-01

    When humid air is exposed to a cold surface whose temperature is below 0 \\C\\, frost deposition occurs and continues to accumulate on the surface. Frost deposition is an important phenomenon in cryogenic industries for use in air conditioners, refrigerators and freeze-out purification, because it causes the drop of thermal efficiency on heat exchangers.This paper presented a review of our previous studies on frost formation with emphasis on the frost growth process, the frost structure, the gr...

  17. Debris Disks: Probing Planet Formation

    Wyatt, Mark C.

    2018-01-01

    Debris disks are the dust disks found around ~20% of nearby main sequence stars in far-IR surveys. They can be considered as descendants of protoplanetary disks or components of planetary systems, providing valuable information on circumstellar disk evolution and the outcome of planet formation. The debris disk population can be explained by the steady collisional erosion of planetesimal belts; population models constrain where (10-100au) and in what quantity (>1Mearth) planetesimals (>10km i...

  18. Kinetically guided colloidal structure formation

    Hecht, Fabian M.; Bausch, Andreas R.

    2016-01-01

    The well-studied self-organization of colloidal particles is predicted to result in a variety of fascinating applications. Yet, whereas self-assembly techniques are extensively explored, designing and producing mesoscale-sized objects remains a major challenge, as equilibration times and thus structure formation timescales become prohibitively long. Asymmetric mesoscopic objects, without prior introduction of asymmetric particles with all its complications, are out of reach––due to the underl...

  19. Formation of a collaborative society

    Buřita, Ladislav; Ondryhal, Vojtěch

    2014-01-01

    The MilUNI knowledge portal, based on the knowledge base developed in ATOM software has been created at the authors' workplace with the aim to form a collaborative society of military universities. The analysis of the collaborative society concept is presented. The description of the MilUNI project is included. Some areas for university cooperation are proposed, as well as the measures facilitating the formation and development of the collaborative society.

  20. THE BLACK HOLE FORMATION PROBABILITY

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

    2015-01-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P BH (M ZAMS ). Although we find that it is difficult to derive a unique P BH (M ZAMS ) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P BH (M ZAMS ) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P BH (M ZAMS ) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment

  1. The Black Hole Formation Probability

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

    2015-02-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P BH(M ZAMS). Although we find that it is difficult to derive a unique P BH(M ZAMS) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P BH(M ZAMS) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P BH(M ZAMS) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  2. Interactions, Starbursts, and Star Formation

    Johan H. Knapen

    2015-12-01

    Full Text Available We study how interactions between galaxies affect star formation within them by considering a sample of almost 1500 of the nearest galaxies, all within a distance of ∼45 Mpc. We use the far-IR emission to define the massive star formation rate (SFR, and then normalise the SFR by the stellar mass of the galaxy to obtain the specific star formation rate (SSFR. We explore the distribution of (SSFR with morphological type and with stellar mass. We calculate the relative enhancement of SFR and SSFR for each galaxy by normalising them by the median SFR and SSFR values of individual control samples of similar non-interacting galaxies. We find that both the median SFR and SSFR are enhanced in interacting galaxies, and more so as the degree of interaction is higher. The increase is moderate, reaching a maximum of a factor of 1.9 for the highest degree of interaction (mergers. While the SFR and SSFR are enhanced statistically by interactions, in many individual interacting galaxies they are not enhanced at all. Our study is based on a representative sample of nearby galaxies and should be used to place constraints on studies based on samples of galaxies at larger distances.

  3. Pattern formation in optical resonators

    Weiss, C O; Larionova, Ye

    2007-01-01

    We review pattern formation in optical resonators. The emphasis is on 'particle-like' structures such as vortices or spatial solitons. On the one hand, similarities impose themselves with other fields of physics (condensed matter, phase transitions, particle physics, fluds/super fluids). On the other hand the feedback is led by the resonator mirrors to bi- and multi-stability of the spatial field structure, which is the basic ingredient for optical information processing. The spatial dimension or the 'parallelism' is the strength of optics compared to electronics (and will have to be employed to fully use the advantages optics offers in information processing). But even in the 'serial' processing tasks of telecoms (e.g. information buffering) spatial resonator solitons can do better than the schemes proposed so far-including 'slow light'. Pattern formation in optical resonators will likely be the key to brain-like information processing like cognition, learning and association; to complement the precise but limited algorithmic capabilities of electronic processing. But even in the short term it will be useful for solving serial optical processing problems. The prospects for technical uses of pattern formation in resonators are one motivation for this research. The fundamental similarities with other fields of physics, on the other hand, inspire transfer of concepts between fields; something that has always proven fruitful for gaining deeper insights or for solving technical problems

  4. Formation mechanisms of metal colloids

    Halaciuga, Ionel

    Highly dispersed uniform metallic particles are widely used in various areas of technology and medicine and are likely to be incorporated into many other applications in the future. It is commonly accepted that size, shape and composition of the particles represent critical factors in most applications. Thus, understanding the mechanisms of formation of metal particles and the ways to control the physical (e.g. shape, size) and chemical (e.g. composition) properties is of great importance. In the current research, the formation of uniform silver spheres is investigated experimentally. The parameters that influence the formation of silver particles when concentrated iso-ascorbic acid and silver-polyamine complex solutions are rapidly mixed were studied in the absence of dispersants. We found that by varying the nature of the amine, temperature, concentration of reactants, silver/amine molar ratio, and the nature of the silver salt, the size of the resulting silver particles can be varied in a wide range (0.08--1.5 microm). The silver particles were formed by aggregation of nanosize subunits as substantiated by both electron microscopy and X-ray diffraction techniques and by the vivid rapid color changes during the chemical precipitation process. From the practical standpoint, the goal of this research was to prepare well dispersed spherical silver particles having a relatively smooth surface and a diameter of about 1 microm to satisfy the demands of the current electronic materials market. A two stage particle growth model previously developed to explain the narrow size distribution occurring in synthesis of gold spheres was applied to the present experimental system, and the parameters that control the size distribution characteristics were identified. The kinetic parameter required to match the final particle size was found to be in agreement with the one used previously in modeling formation of gold spheres, suggesting that similar kinetics governs the

  5. Adsorption-induced step formation

    Thostrup, P.; Christoffersen, Ebbe; Lorensen, Henrik Qvist

    2001-01-01

    Through an interplay between density functional calculations, Monte Carlo simulations and scanning tunneling microscopy experiments, we show that an intermediate coverage of CO on the Pt(110) surface gives rise to a new rough equilibrium structure with more than 50% step atoms. CO is shown to bind...... so strongly to low-coordinated Pt atoms that it can break Pt-Pt bonds and spontaneously form steps on the surface. It is argued that adsorption-induced step formation may be a general effect, in particular at high gas pressures and temperatures....

  6. Formation fracturing by energy waves

    Brandon, C W

    1966-11-28

    A method described for recovering oil from an oil strata penetrated by a well bore includes a step of applying fluid pressure to the interior of the well bore across the face of the stratum, and alternately varying the applied fluid pressure, first above and then below the reservoir pressure. This is in order to fracture and break up the face of the strata from internal pressure exerted on the strata. The pressure is affected using liquefied gas at low pressure across the formation.

  7. Formation Flying and Deformable Instruments

    Rio, Yvon

    2009-01-01

    Astronomers have always attempted to build very stable instruments. They fight all that can cause mechanical deformation or image motion. This has led to well established technologies (autoguide, active optics, thermal control, tip/tilt correction), as well as observing methods based on the use of controlled motion (scanning, micro scanning, shift and add, chopping and nodding). Formation flying disturbs this practice. It is neither possible to reduce the relative motion to very small amplitudes, nor to control it at will. Some impacts on Simbol-X instrument design, and operation are presented.

  8. Formation Flying and Deformable Instruments

    Rio, Yvon

    2009-05-01

    Astronomers have always attempted to build very stable instruments. They fight all that can cause mechanical deformation or image motion. This has led to well established technologies (autoguide, active optics, thermal control, tip/tilt correction), as well as observing methods based on the use of controlled motion (scanning, micro scanning, shift and add, chopping and nodding). Formation flying disturbs this practice. It is neither possible to reduce the relative motion to very small amplitudes, nor to control it at will. Some impacts on Simbol-X instrument design, and operation are presented.

  9. Formative flow in bedrock canyons

    Venditti, J. G.; Kwoll, E.; Rennie, C. D.; Church, M. A.

    2017-12-01

    In alluvial channels, it is widely accepted that river channel configuration is set by a formative flow that represents a balance between the magnitude and frequency of flood flows. The formative flow is often considered to be one that is just capable of filling a river channel to the top of its banks. Flows much above this formative flow are thought to cause substantial sediment transport and rearrange the channel morphology to accommodate the larger flow. This idea has recently been extended to semi-alluvial channels where it has been shown that even with bedrock exposed, the flows rarely exceed that required to entrain the local sediment cover. What constitutes a formative flow in a bedrock canyon is not clear. By definition, canyons have rock walls and are typically incised vertically, removing the possibility of the walls being overtopped, as can occur in an alluvial channel at high flows. Canyons are laterally constrained, have deep scour pools and often have width to maximum depth ratios approaching 1, an order of magnitude lower than alluvial channels. In many canyons, there are a sequence of irregularly spaced scour pools. The bed may have intermittent or seasonal sediment cover, but during flood flows the sediment bed is entrained leaving a bare bedrock channel. It has been suggested that canyons cut into weak, well-jointed rock may adjust their morphology to the threshold for block plucking because the rock bed is labile during exceptionally large magnitude flows. However, this hypothesis does not apply to canyons cut into massive crystalline rock where abrasion is the dominant erosion process. Here, we argue that bedrock canyon morphology is adjusted to a characteristic flow structure developed in bedrock canyons. We show that the deeply scoured canyon floor is adjusted to a velocity inversion that is present at low flows, but gets stronger at high flows. The effect is to increase boundary shear stresses along the scour pool that forms in constricted

  10. Transient formation of forbidden lines

    Rosmej, F.B.; Rosmej, O.N.

    1996-01-01

    An explanation of anomalously long time scales in the transient formation of forbidden lines is proposed. The concept is based on a collisionally induced density dependence of the relaxation times of metastable level populations in transient plasma. Generalization leads to an incorporation of diffusion phenomena. We demonstrate this new concept for the simplest atomic system: the He-like isoelectronic sequence. A new interpretation of the observed long duration and anomalously high intensity of spin-forbidden emission in hot plasmas is given. (author)

  11. Salt formations offer disposal alternative

    Funderburk, R.

    1990-01-01

    This paper discusses how three U.S. firms are spending millions to permit and build underground disposal sites in salt formations. These companies claim salt is the ideal geological medium for holding hazardous wastes. Two Texas locations and one in Michigan have been targeted as future sites for hazardous waste disposal. The Michigan site, outside Detroit, is a former salt mine 2,000 feet beneath the Ford Motor Co. (Detroit) assembly works in Dearborn. Both Texas sites are atop salt domes---one east and one west of Houston

  12. Transient formation of forbidden lines

    Rosmej, F.B. [Bochum Univ., Ruhr (Germany). Inst. fuer Experimentalphysik V; Rosmej, O.N. [VNIIFTRI, Moscow Region (Russian Federation). MISDC

    1996-05-14

    An explanation of anomalously long time scales in the transient formation of forbidden lines is proposed. The concept is based on a collisionally induced density dependence of the relaxation times of metastable level populations in transient plasma. Generalization leads to an incorporation of diffusion phenomena. We demonstrate this new concept for the simplest atomic system: the He-like isoelectronic sequence. A new interpretation of the observed long duration and anomalously high intensity of spin-forbidden emission in hot plasmas is given. (author).

  13. Tube Formation in Nanoscale Materials

    Yan Chenglin

    2008-01-01

    Full Text Available Abstract The formation of tubular nanostructures normally requires layered, anisotropic, or pseudo-layered crystal structures, while inorganic compounds typically do not possess such structures, inorganic nanotubes thus have been a hot topic in the past decade. In this article, we review recent research activities on nanotubes fabrication and focus on three novel synthetic strategies for generating nanotubes from inorganic materials that do not have a layered structure. Specifically, thermal oxidation method based on gas–solid reaction to porous CuO nanotubes has been successfully established, semiconductor ZnS and Nb2O5nanotubes have been prepared by employing sacrificial template strategy based on liquid–solid reaction, and an in situ template method has been developed for the preparation of ZnO taper tubes through a chemical etching reaction. We have described the nanotube formation processes and illustrated the detailed key factors during their growth. The proposed mechanisms are presented for nanotube fabrication and the important pioneering studies are discussed on the rational design and fabrication of functional materials with tubular structures. It is the intention of this contribution to provide a brief account of these research activities.

  14. Supercoil Formation During DNA Melting

    Sayar, Mehmet; Avsaroglu, Baris; Kabakcioglu, Alkan

    2009-03-01

    Supercoil formation plays a key role in determining the structure-function relationship in DNA. Biological and technological processes, such as protein synthesis, polymerase chain reaction, and microarrays relys on separation of the two strands in DNA, which is coupled to the unwinding of the supercoiled structure. This problem has been studied theoretically via Peyrard-Bishop and Poland-Scheraga type models, which include a simple representation of the DNA structural properties. In recent years, computational models, which provide a more realtistic representaion of DNA molecule, have been used to study the melting behavior of short DNA chains. Here, we will present a new coarse-grained model of DNA which is capable of simulating sufficiently long DNA chains for studying the supercoil formation during melting, without sacrificing the local structural properties. Our coarse-grained model successfully reproduces the local geometry of the DNA molecule, such as the 3'-5' directionality, major-minor groove structure, and the helical pitch. We will present our initial results on the dynamics of supercoiling during DNA melting.

  15. Vascular pattern formation in plants.

    Scarpella, Enrico; Helariutta, Ykä

    2010-01-01

    Reticulate tissue systems exist in most multicellular organisms, and the principles underlying the formation of cellular networks have fascinated philosophers, mathematicians, and biologists for centuries. In particular, the beautiful and varied arrangements of vascular tissues in plants have intrigued mankind since antiquity, yet the organizing signals have remained elusive. Plant vascular tissues form systems of interconnected cell files throughout the plant body. Vascular cells are aligned with one another along continuous lines, and vascular tissues differentiate at reproducible positions within organ environments. However, neither the precise path of vascular differentiation nor the exact geometry of vascular networks is fixed or immutable. Several recent advances converge to reconcile the seemingly conflicting predictability and plasticity of vascular tissue patterns. A control mechanism in which an apical-basal flow of signal establishes a basic coordinate system for body axis formation and vascular strand differentiation, and in which a superimposed level of radial organizing cues elaborates cell patterns, would generate a reproducible tissue configuration in the context of an underlying robust, self-organizing structure, and account for the simultaneous regularity and flexibility of vascular tissue patterns. Copyright 2010 Elsevier Inc. All rights reserved.

  16. Beaver assisted river valley formation

    Westbrook, Cherie J.; Cooper, D.J.; Baker, B.W.

    2011-01-01

    We examined how beaver dams affect key ecosystem processes, including pattern and process of sediment deposition, the composition and spatial pattern of vegetation, and nutrient loading and processing. We provide new evidence for the formation of heterogeneous beaver meadows on riverine system floodplains and terraces where dynamic flows are capable of breaching in-channel beaver dams. Our data show a 1.7-m high beaver dam triggered overbank flooding that drowned vegetation in areas deeply flooded, deposited nutrient-rich sediment in a spatially heterogeneous pattern on the floodplain and terrace, and scoured soils in other areas. The site quickly de-watered following the dam breach by high stream flows, protecting the deposited sediment from future re-mobilization by overbank floods. Bare sediment either exposed by scouring or deposited by the beaver flood was quickly colonized by a spatially heterogeneous plant community, forming a beaver meadow. Many willow and some aspen seedlings established in the more heavily disturbed areas, suggesting the site may succeed to a willow carr plant community suitable for future beaver re-occupation. We expand existing theory beyond the beaver pond to include terraces within valleys. This more fully explains how beavers can help drive the formation of alluvial valleys and their complex vegetation patterns as was first postulated by Ruedemann and Schoonmaker in 1938. ?? 2010 John Wiley & Sons, Ltd.

  17. Enthalpy of formation of zircon

    Ellison, A.J.G.; Navrotsky, A.

    1992-01-01

    Using high-temperature solution calorimetry in molt 2PbO · B 2 O 3 , the enthalpy of reaction of the formation of zircon, ZrSiO 4 , from its constituent oxides has been determined: Δ 4 H 977 (ZrSiO 4 ) = -27.9 (±1.9) kJ/mol. With previously reported data for the heat contents of ZrO 2 SiO 2 and ZrSiO 4 and standard-state enthalpies of formation of ZrO 2 and SiO 2 , we obtain Δ f H 298 degrees. (ZrSiO 4 ) = -2034.2 (±3.1) kJ/mol and Δ t G 298 degrees (ZrSiO 4 ) = -1919.8 kJ/mol. The free energy value is in excellent agreement with a range previously estimated from solid-state reaction equilibria. At higher temperature also the data are in close agreement with existing data, though the data sets diverge somewhat with increasing T. In this paper the limitations of the data for predicting the breakdown temperature of zircon into its constituent oxides are discussed

  18. Spiral branches and star formation

    Zasov, A.V.

    1974-01-01

    Origin of spiral branches of galaxies and formation of stars in them are considered from the point of view of the theory of the gravitational gas condensation, one of comparatively young theories. Arguments are presented in favour of the stellar condensation theory. The concept of the star formation of gas is no longer a speculative hypothesis. This is a theory which assumes quantitative verification and explains qualitatively many facts observed. And still our knowledge on the nature of spiral branches is very poor. It still remains vague what processes give origin to spiral branches, why some galaxies have spirals and others have none. And shapes of spiral branches are diverse. Some cases are known when spiral branches spread outside boundaries of galaxies themselves. Such spirals arise exclusively in the region where there are two or some interacting galaxies. Only first steps have been made in the explanation of the galaxy spiral branches, and it is necessary to carry out new observations and new theoretical calculations

  19. The Formation Mechanism of Hydrogels.

    Lu, Liyan; Yuan, Shiliang; Wang, Jing; Shen, Yun; Deng, Shuwen; Xie, Luyang; Yang, Qixiang

    2017-06-12

    Hydrogels are degradable polymeric networks, in which cross-links play a vital role in structure formation and degradation. Cross-linking is a stabilization process in polymer chemistry that leads to the multi-dimensional extension of polymeric chains, resulting in network structures. By cross-linking, hydrogels are formed into stable structures that differ from their raw materials. Generally, hydrogels can be prepared from either synthetic or natural polymers. Based on the types of cross-link junctions, hydrogels can be categorized into two groups: the chemically cross-linked and the physically cross-linked. Chemically cross-linked gels have permanent junctions, in which covalent bonds are present between different polymer chains, thus leading to excellent mechanical strength. Although chemical cross-linking is a highly resourceful method for the formation of hydrogels, the cross-linkers used in hydrogel preparation should be extracted from the hydrogels before use, due to their reported toxicity, while, in physically cross-linked gels, dissolution is prevented by physical interactions, such as ionic interactions, hydrogen bonds or hydrophobic interactions. Physically cross-linked methods for the preparation of hydrogels are the alternate solution for cross-linker toxicity. Both methods will be discussed in this essay. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  20. Dark matter and galaxy formation

    Umemura, Masayuki

    1987-01-01

    We propose a hybrid model of universe for galaxy formation, that is, an Einstein- de Sitter universe dominated by two-component dark matter: massive neutrinos and cold dark matter. In this hybrid model, the first luminous objects are dwarf galaxies. The neutrino density fluctuations produce large-scale high density and low density regions, which consequently evolve to superclusters of galaxies and voids, respectively. Dwarf galaxies are formed preferentially in supercluster regions. In voids, the formation of dwarf galaxies is fairly suppressed by diffuse UV flux from QSOs, and instead a number of expanding clouds are born, which produce Lyα forest as seen in QSO spectra. Ordinary galaxies are expected to form as aggregations of dwarf galaxies. In this model, some galaxies are born also in voids, and they tend to evolve to spiral galaxies. Additionally, if the same number of globular clusters are formed in a dwarf, the specific globular cluster frequencies are expected to be much larger in ellipticals than in spirals. (author)

  1. Enamel formation and amelogenesis imperfecta.

    Hu, Jan C-C; Chun, Yong-Hee P; Al Hazzazzi, Turki; Simmer, James P

    2007-01-01

    Dental enamel is the epithelial-derived hard tissue covering the crowns of teeth. It is the most highly mineralized and hardest tissue in the body. Dental enamel is acellular and has no physiological means of repair outside of the protective and remineralization potential provided by saliva. Enamel is comprised of highly organized hydroxyapatite crystals that form in a defined extracellular space, the contents of which are supplied and regulated by ameloblasts. The entire process is under genetic instruction. The genetic control of amelogenesis is poorly understood, but requires the activities of multiple components that are uniquely important for dental enamel formation. Amelogenesis imperfecta (AI) is a collective designation for the variety of inherited conditions displaying isolated enamel malformations, but the designation is also used to indicate the presence of an enamel phenotype in syndromes. Recently, genetic studies have demonstrated the importance of genes encoding enamel matrix proteins in the etiology of isolated AI. Here we review the essential elements of dental enamel formation and the results of genetic analyses that have identified disease-causing mutations in genes encoding enamel matrix proteins. In addition, we provide a fresh perspective on the roles matrix proteins play in catalyzing the biomineralization of dental enamel. Copyright 2007 S. Karger AG, Basel.

  2. Package Formats for Preserved Digital Material

    Zierau, Eld

    2012-01-01

    This paper presents an investigation of the best suitable package formats for long term digital preservation. The choice of a package format for preservation is crucial for future access, thus a thorough analysis of choice is important. The investigation presented here covers setting up requireme......This paper presents an investigation of the best suitable package formats for long term digital preservation. The choice of a package format for preservation is crucial for future access, thus a thorough analysis of choice is important. The investigation presented here covers setting up...... requirements for package formats used for long term preserved digital material, and using these requirements as the basis for analysing a range of package formats. The result of the concrete investigation is that the WARC format is the package format best suited for the listed requirements. Fulfilling...

  3. Negative ion formation processes: A general review

    Alton, G.D.

    1990-01-01

    The principal negative ion formation processes will be briefly reviewed. Primary emphasis will be placed on the more efficient and universal processes of charge transfer and secondary ion formation through non-thermodynamic surface ionization. 86 refs., 20 figs

  4. FORMATE-BASED FLUIDS: FORMULATION AND APPLICATION

    Nediljka Gaurina-Međimurec

    2008-12-01

    Full Text Available Formate-based fluids has been successfully used in over hunders HPHT well operations since they introduced in field practice. They have many advantages when compared with conventional HPHT drilling and completion fluids such as: minimal formation damage, maintenance of additve properties at high temperatures, reduced hydraulic flow resistance, low potential for differential sticking, naturally lubricating, very low corrosion rates, biodegradable and pose little risk to the environment etc. Formate-based fluids can be applied during deep slim hole drilling, shale drilling, reservoir drilling, salt and gas hydrate formations drilling. The laboratory research was carried out to evaluate the rheological behavior of formate-based fluids as a function of temperature. Formate-based fluids were formulated using potassium formate brine, xanthan polymer, PAC, starch and calcium carbonate. Experimental results show that potassium formate improves the thermal stability of polymers.

  5. Satellite Formation Control Using Atmospheric Drag

    Hajovsky, Blake B

    2007-01-01

    This study investigates the use of a linear quadratic terminal controller to reconfigure satellite formations using atmospheric drag actuated control while minimizing the loss of energy of the formation...

  6. Formation of tax culture in Russia

    Halikova Je.A.

    2014-11-01

    Full Text Available This article deals with the mechanism of the formation of tax culture in Russia, moral and ethical principles, on which based the work of the tax authorities, given the author's idea of the formation of tax culture. We consider the institution of tax advice, its interaction with the tax authorities and its impact on the formation of tax culture.

  7. Formative Constructs Implemented via Common Factors

    Treiblmaier, Horst; Bentler, Peter M.; Mair, Patrick

    2011-01-01

    Recently there has been a renewed interest in formative measurement and its role in properly specified models. Formative measurement models are difficult to identify, and hence to estimate and test. Existing solutions to the identification problem are shown to not adequately represent the formative constructs of interest. We propose a new two-step…

  8. ENDF/B-5 formats manual 1984

    Kinsey, R; Magurno, B A

    1986-09-01

    The ENDF-5 Format, originally the format of the US Evaluated Nuclear Data File ENDF/B-5, was internationally recommended for the computer storage, processing and exchange of evaluated neutron nuclear data. The present document contains the original Formats Manual of 1979, updated with revisions of Nov. 1983. (author) Figs, tabs

  9. String Formatting Considered Harmful for Novice Programmers

    Hughes, Michael C.; Jadud, Matthew C.; Rodrigo, Ma. Mercedes T.

    2010-01-01

    In Java, "System.out.printf" and "String.format" consume a specialised kind of string commonly known as a format string. In our study of first-year students at the Ateneo de Manila University, we discovered that format strings present a substantial challenge for novice programmers. Focusing on their first laboratory we found…

  10. The forensics of fulgurite formation

    Pasek, Matthew A.; Pasek, Virginia D.

    2018-04-01

    Natural disasters such as forest fires can result in extensive and costly property damage. These events may be the result of a human error or system failure triggered by electrical discharge, and in such circumstances may form a fulgurite. Understanding fulgurites and their formation may be critical in determining the cause of the fire or other, shock-related event. Here we identify several distinguishing features of fulgurites formed in association with downed power lines, including the presence of melted conductors, transformation of quartz to cristobalite, and morphological differences including increased glass percentage and smaller internal voids. These features are consequences of how heat is transferred to and through a target rock material as it melts and forms a fulgurite, and are predicted from both first principles of diffusive heat transfer, and empirically-derived reaction kinetics for mineral transformations.

  11. The dynamics of fragment formation

    Keane, D.

    1994-09-01

    We demonstrate that in the Quantum Molecular Dynamics model, dynamical correlations can result in the production rate for final state nucleon clusters (and hence composite fragments) being higher than would be expected if statistics and the available phase space were dominant in determining composite formation. An intranuclear cascade or a Boltzmann-Uehling-Uhlenbeck model, combined with a statistical approach in the late stage of the collision to determine composites, provides an equivalent description only under limited conditions of centrality and beam energy. We use data on participant fragment production in Au + Au collisions in the Bevalac's BOS time projection chamber to map out the parameter space where statistical clustering provides a good description. In particular, we investigate momentum-space densities of fragments up to 4 He as a function of fragment transverse momentum, azimuth relative to the reaction plane, rapidity, multiplicity and beam energy

  12. Field experiments in salt formations

    Kuehn, K.

    1986-01-01

    Field experiments in salt formations started as early as 1965 with Project Salt Vault in the Lyons Mine, Kansas, U.S.A., and with the purchase of the Asse salt mine by the German Federal Government. Underground tests concentrated on the heat dissipation around buried high-level radioactive wastes and the geomechanical consequences of their disposal. Near-field investigations cover the properties of water and gas release, radiolysis and corrosion. Further objectives of field experiments are the development and underground testing of a handling system for high-level wastes. The performance of an underground test disposal for such wastes is not only considered to be necessary for technical and scientific reasons but also for improving public acceptance of the concept of radioactive waste disposal. (author)

  13. Complexity of formation in holography

    Chapman, Shira; Marrochio, Hugo; Myers, Robert C.

    2017-01-01

    It was recently conjectured that the quantum complexity of a holographic boundary state can be computed by evaluating the gravitational action on a bulk region known as the Wheeler-DeWitt patch. We apply this complexity=action duality to evaluate the ‘complexity of formation’ (DOI: 10.1103/PhysRevLett.116.191301; 10.1103/PhysRevD.93.086006), i.e. the additional complexity arising in preparing the entangled thermofield double state with two copies of the boundary CFT compared to preparing the individual vacuum states of the two copies. We find that for boundary dimensions d>2, the difference in the complexities grows linearly with the thermal entropy at high temperatures. For the special case d=2, the complexity of formation is a fixed constant, independent of the temperature. We compare these results to those found using the complexity=volume duality.

  14. Infrared Astronomy and Star Formation

    Evans, N.J.

    1985-01-01

    Infrared astronomy is a natural tool to use in studying star formation because infrared light penetrates the surrounding dust and because protostars are expected to emit infrared light. Infrared mapping and photometry have revealed many compact sources, often embedded in more extensive warm dust associated with a molecular cloud core. More detailed study of these objects is now beginning, and traditional interpretations are being questioned. Some compact sources are now thought to be density enhancements which are not self-luminous. Infrared excesses around young stars may not always be caused by circumstellar dust; speckle measurements have shown that at least some of the excess toward T Tauri is caused by an infrared companion. Spectroscopic studies of the dense, star-forming cores and of the compact objects themselves have uncovered a wealth of new phenomena, including the widespread occurence of energetic outflows. New discoveries with IRAS and with other planned infrared telescopes will continue to advance this field. (author)

  15. Strategy Formation in Eastern Jutland

    Olesen, Kristian

    2008-01-01

      In Eastern Jutland a strategy formation process has been initiated with the aim of developing a strategic spatial plan for the city region.  An organisation has been set up to deal with the first phase of the process, which is to carry out three functional analyses and prepare a common vision...... in the area.   The municipalities acknowledge the articulation of the city region and the initiated planning process.  However, the municipalities might see the arena as means to lobby for infrastructure investments in Eastern Jutland, as it is doubtful whether the municipalities will feel encouraged to enter...... a process, which is aiming at increasing the national regulation within their territory.    The result might very well be that the discussion about future infrastructure investments is not linked to discussions about future urban development in Eastern Jutland.  These aspects raises serious questions about...

  16. Formation and support of prominence

    Forbes, T.G.

    1986-01-01

    A short introduction is given to the concepts discussed by the group on the formation and support of prominences. Only quiescent and long-lived active region prominences were considered, since transient prominence phenomena, such as sprays, surges, H alpha flare-loops, and coronal rain, are dynamically distinct from long-lived, prominences. Stable prominences (which are often referred to as filaments when seen against the disk) can be subdivided into three categories, namely active region prominences, quiescent prominences and polar crown prominences. The third category is closely related to the second since a quiescent prominence will eventually evolve into a polar crown prominence if it lasts long enough. The distinction between the first and second categories is not sharp either since intermediates exist here as well (Martin, 1973)

  17. New Office Software course format

    HR Department

    2010-01-01

    Always interested to anticipate your training needs, the Technical Training service is pleased to propose two new Office Software course formats : “Focus on... ” : On a monthly basis we will propose a theme such as “Sharepoint Collaboration Workspace” or “Word 2007” or “charts” etc. You will have to send us in advance your questions regarding the proposed topic and register for the course through our Training Catalogue. During the session, our trainer will answer all the questions received and participants will increase their knowledge thanks to the solutions discussed for everyone. The course will last two hours, from 09h00 to 11h00 - with open questions on the proposed topic at the end. “Office software Individual coaching”: If one or several particular topics cause you sleepless nights, you can get the help of our trainer who will come to your workplace for a multiple of 1-hour slots . All fields ...

  18. Accretion Processes in Star Formation

    Küffmeier, Michael

    for short-lived radionuclides that enrich the cloud as a result of supernova explosions of the massive stars allows us to analyze the distribution of the short-lived radionuclides around young forming stars. In contradiction to results from highly-idealized models, we find that the discrepancy in 26 Al...... that the accretion process of stars is heterogeneous in space, time and among different protostars. In some cases, disks form a few thousand years after stellar birth, whereas in other cases disk formation is suppressed due to efficient removal of angular momentum. Angular momentum is mainly transported outward...... with potentially observable fluctuations in the luminosity profile that are induced by variations in the accretion rate. Considering that gas inside protoplanetary disks is not fully ionized, I implemented a solver that accounts for nonideal MHD effects into a newly developed code framework called dispatch...

  19. String Formation Beyond Leading Colour

    Christiansen, Jesper R.

    2015-08-03

    We present a new model for the hadronisation of multi-parton systems, in which colour correlations beyond leading $N_C$ are allowed to influence the formation of confining potentials (strings). The multiplet structure of $SU(3)$ is combined with a minimisation of the string potential energy, to decide between which partons strings should form, allowing also for "baryonic" configurations (e.g., two colours can combine coherently to form an anticolour). In $e^+e^-$collisions, modifications to the leading-colour picture are small, suppressed by both colour and kinematics factors. But in $pp$ collisions, multi-parton interactions increase the number of possible subleading connections, counteracting their naive $1/N_C^2$ suppression. Moreover, those that reduce the overall string lengths are kinematically favoured. The model, which we have implemented in the PYTHIA 8 generator, is capable of reaching agreement not only with the important $\\left(n_\\mathrm{charged})$ distribution but also with measured rates (and ra...

  20. Restucturing the Project Work Format

    Dupont, Søren

    2015-01-01

    The chapter is based on an evaluation of a pedagogical experiment at Roskilde University, the Antology Experiment. The objective of the experiment was to develop and expand the framework for project work through the production of anthologies compiled collectively by a number of project groups....... The novel aspects of the Anthology Experiment were most notably its magnitude and complexity. In this experiment the groups were totalling some 50 students who were working together. The experiment used a well-known publishing format from research, namely the anthology form, which usually focuses...... on a specific research topic and includes contributions from various researchers. In the Anthology Experiment, the project groups could be viewed as ‘research units’ that produce the contributions to the anthology. The complexity of the experiment offered challenges, both for students and supervisors...

  1. Price formation and market mechanisms

    Neff, T.L.

    1991-01-01

    World markets for nuclear fuel have changed greatly since the 1970s. In earlier days, firms specializing in mining, conversion, enrichment and fabrication negotiated directly with end users, primarily under long term contracts at specified prices. This old model is gone. Market structure has been transformed: traditional suppliers now compete with traders, some of whom can offer a much larger menu of products and terms than primary suppliers. Utilities act as traders, converters as brokers, brokers as traders, producers as buyers, and so on. De-enrichment, de-conversion, loans, swaps, interchanges and other new kinds of transactions have proliferated. These changes in market structure and market mechanisms have been accompanied by substantial changes in price formation, that is the process by which market price is set. Today, the level and direction of price are set in a trading dominated spot market environment, fuelled by inventory liquidation and Soviet and other non-traditional supply. (author)

  2. Complexity of formation in holography

    Chapman, Shira [Perimeter Institute for Theoretical Physics,Waterloo, ON N2L 2Y5 (Canada); Marrochio, Hugo [Perimeter Institute for Theoretical Physics,Waterloo, ON N2L 2Y5 (Canada); Department of Physics & Astronomy and Guelph-Waterloo Physics Institute,University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Myers, Robert C. [Perimeter Institute for Theoretical Physics,Waterloo, ON N2L 2Y5 (Canada)

    2017-01-16

    It was recently conjectured that the quantum complexity of a holographic boundary state can be computed by evaluating the gravitational action on a bulk region known as the Wheeler-DeWitt patch. We apply this complexity=action duality to evaluate the ‘complexity of formation’ (DOI: 10.1103/PhysRevLett.116.191301; 10.1103/PhysRevD.93.086006), i.e. the additional complexity arising in preparing the entangled thermofield double state with two copies of the boundary CFT compared to preparing the individual vacuum states of the two copies. We find that for boundary dimensions d>2, the difference in the complexities grows linearly with the thermal entropy at high temperatures. For the special case d=2, the complexity of formation is a fixed constant, independent of the temperature. We compare these results to those found using the complexity=volume duality.

  3. Uranium price formation. Final report

    1977-10-01

    The modern uranium industry came into existence in 1946. Until 1966, its sole customer was the Atomic Energy Commission, whose needs for U 3 O 8 relative to industry capacity declined over the years. The development of the commercial market after 1965 coincided with a period of excess capacity and falling nominal and real prices. Gradually in 1973 and dramatically thereafter, market conditions changed and prices rose as utilities sought larger quantities of U 3 O 8 and longer term contracts. Questions about availability of long-run supplies were raised, given the known reserve base. The response of the supply of U 3 O 8 to incentives offered first by the AEC and later by the utilities in the context of new and developing market conventions is examined. The methodology used is microeconomic analysis, qualitatively applied to the history of price formation in the market. Because the study emphasizes the implications of the history of uranium price formation for forecasting supply response, the study presents many different kinds of data and evaluates their quality and appropriateness for forecasting. A simple, very-useful framework for analyzing the history of the market for U 3 O 8 was developed and used to describe supply responses in selected important periods of the industry's development. It is concluded that the response of supply of U 3 O 8 to rising prices or to expectations of demand growth has been impressively strong. The potential reserve inventory is large enough to meet the needs for nuclear power generation through the end of this century. The price necessary to induce producers to find and produce these reserves is uncertain, partly because of problems inherent in estimating long-run supply curves and partly because recent inflation has created major uncertainties about the cost of future supplies

  4. Thermal Behaviour of clay formations

    Tassoni, E.

    1985-01-01

    The programme carried out by ENEA to model the thermal-hydraulic-mechanical behaviour of the clay formations and to measure, in situ and in laboratory, the thermal properties of these rocks, is presented. An in situ heating experiment has been carried out in an open clay quarry in the area of Monterotondo, near Rome. The main goal of the experiment was to know the temperature field and the thermal effects caused by the high level radioactive waste disposed of in a clayey geological formation. The conclusions are as follows: - the thermal conduction codes are sufficiently accurate to forecast the temperature increases caused in the clay by the dissipation of the heat generated by high level radioactive waste; - the thermal conductivity deduced by means of the ''curve fitting'' method ranges from 0.015 to 0.017 W.cm -1 . 0 C -1 - the temperature variation associated with the transport of clay interstitial water caused by temperature gradient is negligible. A laboratory automated method has been designed to measure the thermal conductivity and diffusivity in clay samples. A review of experimental data concerning thermomechanical effects in rocks as well as results of thermal experiments performed at ISMES on clays are presented. Negative thermal dilation has been found both in the elastic and plastic range under constant stress. Thermoplastic deformation appears ten times greater than the thermoelastic one. A mathematical model is proposed in order to simulate the above and other effects that encompass thermal-elastic-plastic-pore water pressure response of clays at high temperature and effective pressure with undrained and transient drainage conditions. Implementation of the two versions into a finite element computer code is described

  5. Drill cuttings mount formation study

    Teh, Su Yean; Koh, Hock Lye

    2014-07-01

    Oil, Gas and Energy sector has been identified as an essential driving force in the Malaysian Economic Transformation Programs (ETP). Recently confirmed discovery of many offshore oil and gas deposits in Malaysian waters has ignited new confidence in this sector. However, this has also spurred intense interest on safeguarding the health and environment of coastal waters in Malaysia from adverse impact resulting from offshore oil and gas production operation. Offshore discharge of spent drilling mud and rock cuttings is the least expensive and simplest option to dispose of large volumes of drilling wastes. But this onsite offshore disposal may have adverse environmental impacts on the water column and the seabed. It may also pose occupational health hazards to the workers living in the offshore platforms. It is therefore important to model the transport and deposition of drilling mud and rock cuttings in the sea to enable proper assessment of their adverse impacts on the environment and the workers. Further, accumulation of drill particles on the seabed may impede proper operation of pipelines on the seabed. In this paper, we present an in-house application model TUNA-PT developed to cater to local oil and gas industry needs to simulate the dispersion and mount formation of drill cuttings by offshore oil and gas exploration and production platforms. Using available data on Malaysian coastal waters, simulation analyses project a pile formation on the seabed with a maximum height of about 1 m and pile radius of around 30 to 50 m. Simulated pile heights are not sensitive to the heights of release of the cuttings as the sensitivity has been mitigated by the depth of water.

  6. Engram Formation in Psychiatric Disorders

    Peter J. Gebicke-Haerter

    2014-05-01

    Full Text Available Environmental factors substantially influence beginning and progression of mental illness, reinforcing or reducing the consequences of genetic vulnerability. Often initiated by early traumatic events, engrams or memories are formed that may give rise to a slow and subtle progression of psychiatric disorders. The large delay between beginning and time of onset (diagnosis may be explained by efficient compensatory mechanisms observed in brain metabolism that use optional pathways in highly redundant molecular interactions.To this end, research has to deal with mechanisms of learning and long-term memory formation, which involves a epigenetic changes, b altered neuronal activities and c changes in neuron-glia communication. On the epigenetic level, apparently DNA-methylations are more stable than histone modifications, although both closely interact. Neuronal activities basically deliver digital information, which clearly can serve as basis for memory formation (LTP. However, research in this respect has long time neglected the importance of glia. They are more actively involved in the control of neuronal activities than thought before. They can both reinforce and inhibit neuronal activities by transducing neuronal information from frequency-encoded to amplitude and frequency-modulated calcium wave patterns spreading in the glial syncytium by use of gap junctions. In this way, they serve integrative functions. In conclusion, we are dealing with two concepts of encoding information that mutually control each other and synergize: a digital (neuronal and a wave-like (glial computing, forming neuron-glia functional units with inbuilt feedback loops to maintain balance of excitation and inhibition. To better understand mental illness, we have to gain more insight into the dynamics of adverse environmental impact on those cellular and molecular systems. This report summarizes existing knowledge and draws some outline about further research in molecular

  7. Heating tar sands formations while controlling pressure

    Stegemeier, George Leo [Houston, TX; Beer, Gary Lee [Houston, TX; Zhang, Etuan [Houston, TX

    2010-01-12

    Methods for treating a tar sands formation are described herein. Methods may include heating at least a section of a hydrocarbon layer in the formation from a plurality of heaters located in the formation. A pressure in the majority of the section may be maintained below a fracture pressure of the formation. The pressure in the majority of the section may be reduced to a selected pressure after the average temperature reaches a temperature that is above 240.degree. C. and is at or below pyrolysis temperatures of hydrocarbons in the section. At least some hydrocarbon fluids may be produced from the formation.

  8. Radiogeochemical features of hydrothermal metasomatic formations

    Plyushchev, E.V.; Ryabova, L.A.; Shatov, V.V.

    1978-01-01

    Considered are the most general peculiarities of uranium and thorium distributions in hydrothermal-metasomatic formations of three levels of substance formation: 1) in hydrothermal minerals; 2) in natural associations of these minerals (in the altered rocks, metasomatites, ores, etc.); 3) ordened series of zonally and in stage conjugated hydrothermal-metasomatic formations. Statistically stable recurrence of natural combinations of hydrothermal-metasomatic formations points out conjugation of their formation in the directed evolution in the general hydrothermal process. Series of metasomatic formations, the initial members of which are potassium metasomatites, mostly result in accumulation up to industrial concentrations of radioactive elements in final members of these formations. Development of midlow-temperature propylitic alterations in highly radiative rocks causes the same accumulation

  9. Improving the Formatting Tools of CDS Invenio

    Caffaro, J; Pu Faltings, Pearl

    2006-01-01

    CDS Invenio is the web-based integrated digital library system developed at CERN. It is a strategical tool that supports the archival and open dissemination of documents produced by CERN researchers. This paper reports on my Master’s thesis work done on BibFormat, a module in CDS Invenio, which formats documents metadata. The goal of this project was to implement a completely new formatting module for CDS Invenio. In this report a strong emphasis is put on the user-centered design of the new BibFormat. The bibliographic formatting process and its requirements are discussed. The task analysis and its resulting interaction model are detailed. The document also shows the implemented user interface of BibFormat and gives the results of the user evaluation of this interface. Finally the results of a small usability study of the formats included in CDS Invenio are discussed.

  10. Fibril formation from pea protein and subsequent gel formation.

    Munialo, Claire Darizu; Martin, Anneke H; van der Linden, Erik; de Jongh, Harmen H J

    2014-03-19

    The objective of this study was to characterize fibrillar aggregates made using pea proteins, to assemble formed fibrils into protein-based gels, and to study the rheological behavior of these gels. Micrometer-long fibrillar aggregates were observed after pea protein solutions had been heated for 20 h at pH 2.0. Following heating of pea proteins, it was observed that all of the proteins were hydrolyzed into peptides and that 50% of these peptides were assembled into fibrils. Changes on a structural level in pea proteins were studied using circular dichroism, transmission electron microscopy, and particle size analysis. During the fibril assembly process, an increase in aggregate size was observed, which coincided with an increase in thioflavin T binding, indicating the presence of β-sheet aggregates. Fibrils made using pea proteins were more branched and curly. Gel formation of preformed fibrils was induced by slow acidification from pH 7.0 to a final pH of around pH 5.0. The ability of pea protein-based fibrillar gels to fracture during an amplitude sweep was comparable to those of soy protein and whey protein-based fibrillar gels, although gels prepared from fibrils made using pea protein and soy protein were weaker than those of whey protein. The findings show that fibrils can be prepared from pea protein, which can be incorporated into protein-based fibrillar gels.

  11. Magnetic Assisted Colloidal Pattern Formation

    Yang, Ye

    Pattern formation is a mysterious phenomenon occurring at all scales in nature. The beauty of the resulting structures and myriad of resulting properties occurring in naturally forming patterns have attracted great interest from scientists and engineers. One of the most convenient experimental models for studying pattern formation are colloidal particle suspensions, which can be used both to explore condensed matter phenomena and as a powerful fabrication technique for forming advanced materials. In my thesis, I have focused on the study of colloidal patterns, which can be conveniently tracked in an optical microscope yet can also be thermally equilibrated on experimentally relevant time scales, allowing for ground states and transitions between them to be studied with optical tracking algorithms. In particular, I have focused on systems that spontaneously organize due to particle-surface and particle-particle interactions, paying close attention to systems that can be dynamically adjusted with an externally applied magnetic or acoustic field. In the early stages of my doctoral studies, I developed a magnetic field manipulation technique to quantify the adhesion force between particles and surfaces. This manipulation technique is based on the magnetic dipolar interactions between colloidal particles and their "image dipoles" that appear within planar substrate. Since the particles interact with their own images, this system enables massively parallel surface force measurements (>100 measurements) in a single experiment, and allows statistical properties of particle-surface adhesion energies to be extracted as a function of loading rate. With this approach, I was able to probe sub-picoNewton surface interactions between colloidal particles and several substrates at the lowest force loading rates ever achieved. In the later stages of my doctoral studies, I focused on studying patterns formed from particle-particle interaction, which serve as an experimental model of

  12. Benzene formation in electronic cigarettes.

    James F Pankow

    Full Text Available The heating of the fluids used in electronic cigarettes ("e-cigarettes" used to create "vaping" aerosols is capable of causing a wide range of degradation reaction products. We investigated formation of benzene (an important human carcinogen from e-cigarette fluids containing propylene glycol (PG, glycerol (GL, benzoic acid, the flavor chemical benzaldehyde, and nicotine.Three e-cigarette devices were used: the JUULTM "pod" system (provides no user accessible settings other than flavor cartridge choice, and two refill tank systems that allowed a range of user accessible power settings. Benzene in the e-cigarette aerosols was determined by gas chromatography/mass spectrometry. Benzene formation was ND (not detected in the JUUL system. In the two tank systems benzene was found to form from propylene glycol (PG and glycerol (GL, and from the additives benzoic acid and benzaldehyde, especially at high power settings. With 50:50 PG+GL, for tank device 1 at 6W and 13W, the formed benzene concentrations were 1.9 and 750 μg/m3. For tank device 2, at 6W and 25W, the formed concentrations were ND and 1.8 μg/m3. With benzoic acid and benzaldehyde at ~10 mg/mL, for tank device 1, values at 13W were as high as 5000 μg/m3. For tank device 2 at 25W, all values were ≤~100 μg/m3. These values may be compared with what can be expected in a conventional (tobacco cigarette, namely 200,000 μg/m3. Thus, the risks from benzene will be lower from e-cigarettes than from conventional cigarettes. However, ambient benzene air concentrations in the U.S. have typically been 1 μg/m3, so that benzene has been named the largest single known cancer-risk air toxic in the U.S. For non-smokers, chronically repeated exposure to benzene from e-cigarettes at levels such as 100 or higher μg/m3 will not be of negligible risk.

  13. Method of developing thick sloping coal formations

    Bragintsev, V F; Mashkovtsev, I L; Semenov, V S; Zykov, V N

    1980-04-25

    A method is patented for developing thick sloping coal formations in 3 inclined layers. It includes conducting developmental operations for each of the layers until one begins the last one and extraction of the layers. In order to improve effectivess and extraction operation safety one first carried out preliminary development of a formation in thin strips beneath protected objects when extracting formation which contain alot of gas. Then one removes the gas of a formation through boreholes that have been drilled into the formation from the indicated workings. Then one works the upper layer in thin strips in a sequence from the roof of the formation to the floor of the upper layer. The one strengthens roof rock of the formation by pumping in a quickly hardening solution into the boreholes which have been drilled into the roof of the formation after processing the upper layer. The middle layer is worked in thin strips in the sequence from the roof to the ground of the middle layer, then the lower layer of the formation is strengthened by pumping in quickly hardening solution into the formation along degasified boreholes and it is worked in thin strips in sequence from the ground of the lower to its roof. Workings are shaped respectively for the middle and lower layers by deepening workings of the upper and middle layers. The layers are worked respectively after finishing displacement of the roof in front of the extraction face of each subsequent extraction of a layer in alternating fashion.

  14. String formation beyond leading colour

    Christiansen, Jesper R. [Department of Astronomy and Theoretical Physics, Lund University,Sölvegatan 14, Lund (Sweden); Theoretical Physics, CERN,CH-1211, Geneva 23 (Switzerland); Skands, Peter Z. [Theoretical Physics, CERN,CH-1211, Geneva 23 (Switzerland); School of Physics and Astronomy, Monash University,VIC-3800 (Australia)

    2015-08-03

    We present a new model for the hadronisation of multi-parton systems, in which colour correlations beyond leading N{sub C} are allowed to influence the formation of confining potentials (strings). The multiplet structure of SU(3) is combined with a minimisation of the string potential energy, to decide between which partons strings should form, allowing also for “baryonic” configurations (e.g., two colours can combine coherently to form an anticolour). In e{sup +}e{sup −}collisions, modifications to the leading-colour picture are small, suppressed by both colour and kinematics factors. But in pp collisions, multi-parton interactions increase the number of possible subleading connections, counteracting their naive 1/N{sub C}{sup 2} suppression. Moreover, those that reduce the overall string lengths are kinematically favoured. The model, which we have implemented in the PYTHIA 8 generator, is capable of reaching agreement not only with the important 〈p{sub ⊥}〉(n{sub charged}) distribution but also with measured rates (and ratios) of kaons and hyperons, in both ee and pp collisions. Nonetheless, the shape of their p{sub ⊥} spectra remains challenging to explain.

  15. Galaxy formation and physical bias

    Cen, Renyue; Ostriker, Jeremiah P.

    1992-01-01

    We have supplemented our code, which computes the evolution of the physical state of a representative piece of the universe to include, not only the dynamics of dark matter (with a standard PM code), and the hydrodynamics of the gaseous component (including detailed collisional and radiative processes), but also galaxy formation on a heuristic but plausible basis. If, within a cell the gas is Jeans' unstable, collapsing, and cooling rapidly, it is transformed to galaxy subunits, which are then followed with a collisionless code. After grouping them into galaxies, we estimate the relative distributions of galaxies and dark matter and the relative velocities of galaxies and dark matter. In a large scale CDM run of 80/h Mpc size with 8 x 10 exp 6 cells and dark matter particles, we find that physical bias b is on the 8/h Mpc scale is about 1.6 and increases towards smaller scales, and that velocity bias is about 0.8 on the same scale. The comparable HDM simulation is highly biased with b = 2.7 on the 8/h Mpc scale. Implications of these results are discussed in the light of the COBE observations which provide an accurate normalization for the initial power spectrum. CDM can be ruled out on the basis of too large a predicted small scale velocity dispersion at greater than 95 percent confidence level.

  16. Stages of neuronal network formation

    Woiterski, Lydia; Käs, Josef A; Claudepierre, Thomas; Luxenhofer, Robert; Jordan, Rainer

    2013-01-01

    Graph theoretical approaches have become a powerful tool for investigating the architecture and dynamics of complex networks. The topology of network graphs revealed small-world properties for very different real systems among these neuronal networks. In this study, we observed the early development of mouse retinal ganglion cell (RGC) networks in vitro using time-lapse video microscopy. By means of a time-resolved graph theoretical analysis of the connectivity, shortest path length and the edge length, we were able to discover the different stages during the network formation. Starting from single cells, at the first stage neurons connected to each other ending up in a network with maximum complexity. In the further course, we observed a simplification of the network which manifested in a change of relevant network parameters such as the minimization of the path length. Moreover, we found that RGC networks self-organized as small-world networks at both stages; however, the optimization occurred only in the second stage. (paper)

  17. Dark Energy and Structure Formation

    Singh, Anupam

    2010-01-01

    We study the gravitational dynamics of dark energy configurations. We report on the time evolution of the dark energy field configurations as well as the time evolution of the energy density to demonstrate the gravitational collapse of dark energy field configurations. We live in a Universe which is dominated by Dark Energy. According to current estimates about 75% of the Energy Density is in the form of Dark Energy. Thus when we consider gravitational dynamics and Structure Formation we expect Dark Energy to play an important role. The most promising candidate for dark energy is the energy density of fields in curved space-time. It therefore become a pressing need to understand the gravitational dynamics of dark energy field configurations. We develop and describe the formalism to study the gravitational collapse of fields given any general potential for the fields. We apply this formalism to models of dark energy motivated by particle physics considerations. We solve the resulting evolution equations which determine the time evolution of field configurations as well as the dynamics of space-time. Our results show that gravitational collapse of dark energy field configurations occurs and must be considered in any complete picture of our universe.

  18. Chloride Transport in Heterogeneous Formation

    Mukherjee, A.; Holt, R. M.

    2017-12-01

    The chloride mass balance (CMB) is a commonly-used method for estimating groundwater recharge. Observations of the vertical distribution of pore-water chloride are related to the groundwater infiltration rates (i.e. recharge rates). In CMB method, the chloride distribution is attributed mainly to the assumption of one dimensional piston flow. In many places, however, the vertical distribution of chloride will be influenced by heterogeneity, leading to horizontal movement of infiltrating waters. The impact of heterogeneity will be particularly important when recharge is locally focused. When recharge is focused in an area, horizontal movement of chloride-bearing waters, coupled with upward movement driven by evapotranspiration, may lead to chloride bulges that could be misinterpreted if the CMB method is used to estimate recharge. We numerically simulate chloride transport and evaluate the validity of the CMB method in highly heterogeneous systems. This simulation is conducted for the unsaturated zone of Ogallala, Antlers, and Gatuna (OAG) formations in Andrews County, Texas. A two dimensional finite element model will show the movement of chloride through heterogeneous systems. We expect to see chloride bulges not only close to the surface but also at depths characterized by horizontal or upward movement. A comparative study of focused recharge estimates in this study with available recharge data will be presented.

  19. New Office Software course format!

    HR Department

    Always keen to anticipate your  training needs, the Technical Training service is pleased to propose two new Office Software course formats: “Focus on... ”:  On a monthly basis we will propose a theme such as “Sharepoint Collaboration Workspace” or “Word 2007” or “charts”, etc.  You will be invited to send us in advance your questions regarding the proposed topic and register  for the course through our Training Catalogue. During the session, our trainer will answer all the questions received and participants will increase their knowledge thanks to the solutions discussed for everyone. The course will last two hours, from 9-00 to 11-00 a.m. - with open questions on the proposed topic at the end.   “Office software Individual coaching”: If one or more specific topics are causing you sleepless nights, you can get the help of our trainer who will ...

  20. New Office Software course format!

    HR Department

    2009-01-01

    Always keen to anticipate your  training needs, the Technical Training service is pleased to propose two new Office Software course formats: “Focus on... ”:  On a monthly basis we will propose a theme such as “Sharepoint Collaboration Workspace” or “Word 2007” or “charts”, etc.  You will be invited to send us in advance your questions regarding the proposed topic and register  for the course through our Training Catalogue. During the session, our trainer will answer all the questions received and participants will increase their knowledge thanks to the solutions discussed for everyone. The course will last two hours, from 9-00 to 11-00 a.m. - with open questions on the proposed topic at the end.   “Office software Individual coaching”: If one or more specific topics are causing you sleepless nights, you can get the help of our trainer who will ...

  1. Formation of submarine gas hydrates

    Soloviev, V.; Ginsburg, G.D. (Reserch Institute of Geology and Mineral Resources of the Ocean ' ' VNII Okeangeologia' ' , St. Petersburg (Russian Federation))

    1994-03-01

    Submarine gas hydrates have been discoverd in the course of deep-sea drilling (DSDP and ODP) and bottom sampling in many offshore regions. This paper reports on expeditions carried out in the Black, Caspian and Okhotsk Seas. Gas hydrate accumulations were discovered and investigated in all these areas. The data and an analysis of the results of the deep-sea drilling programme suggest that the infiltration of gas-bearing fluids is a necessary condition for gas hydrate accumulation. This is confirmed by geological observations at three scale levels. Firstly, hydrates in cores are usually associated with comparatively coarse-grained, permeable sediments as well as voids and fractures. Secondly, hydrate accumulations are controlled by permeable geological structures, i.e. faults, diapirs, mud volcanos as well as layered sequences. Thirdly, in the worldwide scale, hydrate accumulations are characteristic of continental slopes and rises and intra-continental seas where submarine seepages also are widespread. Both biogenic and catagenic gas may occur, and the gas sources may be located at various distances from the accumulation. Gas hydrates presumably originate from water-dissolved gas. The possibility of a transition from dissolved gas into hydrate is confirmed by experimental data. Shallow gas hydrate accumulations associated with gas-bearing fluid plumes are the most convenient features for the study of submarine hydrate formation in general. These accumulations are known from the Black, Caspian and Okhotsk Seas, the Gulf of Mexico and off northern California. (au) (24 refs.)

  2. STAR FORMATION IN DENSE CLUSTERS

    Myers, Philip C.

    2011-01-01

    A model of core-clump accretion with equally likely stopping describes star formation in the dense parts of clusters, where models of isolated collapsing cores may not apply. Each core accretes at a constant rate onto its protostar, while the surrounding clump gas accretes as a power of protostar mass. Short accretion flows resemble Shu accretion and make low-mass stars. Long flows resemble reduced Bondi accretion and make massive stars. Accretion stops due to environmental processes of dynamical ejection, gravitational competition, and gas dispersal by stellar feedback, independent of initial core structure. The model matches the field star initial mass function (IMF) from 0.01 to more than 10 solar masses. The core accretion rate and the mean accretion duration set the peak of the IMF, independent of the local Jeans mass. Massive protostars require the longest accretion durations, up to 0.5 Myr. The maximum protostar luminosity in a cluster indicates the mass and age of its oldest protostar. The distribution of protostar luminosities matches those in active star-forming regions if protostars have a constant birthrate but not if their births are coeval. For constant birthrate, the ratio of young stellar objects to protostars indicates the star-forming age of a cluster, typically ∼1 Myr. The protostar accretion luminosity is typically less than its steady spherical value by a factor of ∼2, consistent with models of episodic disk accretion.

  3. Shock formation within sonoluminescence bubbles

    Vuong, V.Q.; Szeri, A.J.; Young, D.A.

    1999-01-01

    A strong case has been made by several authors that sharp, spherically symmetric shocks converging on the center of a spherical bubble driven by a strong acoustic field give rise to rapid compression and heating that produces the brief flash of light known as sonoluminescence. The formation of such shocks is considered. It is found that, although at the main collapse the bubble wall does indeed launch an inwardly-traveling compression wave, and although the subsequent reflection of the wave at the bubble center produces a very rapid temperature peak, the wave is prevented from steepening into a sharp shock by an adverse gradient in the sound speed caused by heat transfer. It is shown that the mathematical characteristics of the flow can be prevented from accumulating into a shock front by this adverse sound speed gradient. A range of results is presented for a variety of bubble ambient radii and sound field amplitudes suggested by experiments. The time scale of the peak temperature in the bubble is set by the dynamics of the compression wave: this is typically in the range 100 - 300 ps (FWHM) in concert with recent measurements of the sonoluminescence pulse width. copyright 1999 American Institute of Physics

  4. Spheromak formation studies in SSPX

    Hill, D.N.; Bulmer, R.H.; Cohen, B.L.; Hooper, E.B.; LoDestro, L.L.; Mattor, N.; McLean, H.S.; Moller, J.; Pearlstein, L.D.; Ryutov, D.D.; Stallard, B.W.; Wood, R.D.; Woodruff, S.; Holcomb, C.T.; Jarboe, T.; Sovinec, C.R.; Wang, Z.; Wurden, G.

    2000-01-01

    We present results from the Sustained Spheromak Physics Experiment (SSPX) at LLNL, which has been built to study energy confinement in spheromak plasmas sustained for up to 2 ms by coaxial DC helicity injection. Peak toroidal currents as high as 600kA have been obtained in the 1m dia. (0.23m minor radius) device using injection currents between 200-400kA; these currents generate edge poloidal fields in the range of 0.2-0.4T. The internal field and current profiles are inferred from edge field measurements using the CORSICA code. Density and impurity control is obtained using baking, glow discharge cleansing, and titanium gettering, after which long plasma decay times (τ (ge) 1.5ms) are observed and impurity radiation losses are reduced from ∼50% to e (0)∼120eV and β e ∼7%. Edge field measurements show the presence of n=1 modes during the formation phase, as has been observed in other spheromaks. This mode dies away during sustainment and decay so that edge fluctuation levels as low as 1% have been measured. These results are compared with numerical simulations using the NIMROD code

  5. SPMHD simulations of structure formation

    Barnes, David J.; On, Alvina Y. L.; Wu, Kinwah; Kawata, Daisuke

    2018-05-01

    The intracluster medium of galaxy clusters is permeated by μ {G} magnetic fields. Observations with current and future facilities have the potential to illuminate the role of these magnetic fields play in the astrophysical processes of galaxy clusters. To obtain a greater understanding of how the initial seed fields evolve to the magnetic fields in the intracluster medium requires magnetohydrodynamic simulations. We critically assess the current smoothed particle magnetohydrodynamic (SPMHD) schemes, especially highlighting the impact of a hyperbolic divergence cleaning scheme and artificial resistivity switch on the magnetic field evolution in cosmological simulations of the formation of a galaxy cluster using the N-body/SPMHD code GCMHD++. The impact and performance of the cleaning scheme and two different schemes for the artificial resistivity switch is demonstrated via idealized test cases and cosmological simulations. We demonstrate that the hyperbolic divergence cleaning scheme is effective at suppressing the growth of the numerical divergence error of the magnetic field and should be applied to any SPMHD simulation. Although the artificial resistivity is important in the strong field regime, it can suppress the growth of the magnetic field in the weak field regime, such as galaxy clusters. With sufficient resolution, simulations with divergence cleaning can reproduce observed magnetic fields. We conclude that the cleaning scheme alone is sufficient for galaxy cluster simulations, but our results indicate that the SPMHD scheme must be carefully chosen depending on the regime of the magnetic field.

  6. Decentralized Control for Scalable Quadcopter Formations

    Qasim Ali

    2016-01-01

    Full Text Available An innovative framework has been developed for teamwork of two quadcopter formations, each having its specified formation geometry, assigned task, and matching control scheme. Position control for quadcopters in one of the formations has been implemented through a Linear Quadratic Regulator Proportional Integral (LQR PI control scheme based on explicit model following scheme. Quadcopters in the other formation are controlled through LQR PI servomechanism control scheme. These two control schemes are compared in terms of their performance and control effort. Both formations are commanded by respective ground stations through virtual leaders. Quadcopters in formations are able to track desired trajectories as well as hovering at desired points for selected time duration. In case of communication loss between ground station and any of the quadcopters, the neighboring quadcopter provides the command data, received from the ground station, to the affected unit. Proposed control schemes have been validated through extensive simulations using MATLAB®/Simulink® that provided favorable results.

  7. Autonomous Formations of Multi-Agent Systems

    Dhali, Sanjana; Joshi, Suresh M.

    2013-01-01

    Autonomous formation control of multi-agent dynamic systems has a number of applications that include ground-based and aerial robots and satellite formations. For air vehicles, formation flight ("flocking") has the potential to significantly increase airspace utilization as well as fuel efficiency. This presentation addresses two main problems in multi-agent formations: optimal role assignment to minimize the total cost (e.g., combined distance traveled by all agents); and maintaining formation geometry during flock motion. The Kuhn-Munkres ("Hungarian") algorithm is used for optimal assignment, and consensus-based leader-follower type control architecture is used to maintain formation shape despite the leader s independent movements. The methods are demonstrated by animated simulations.

  8. Reflections about the mathematics teachers' formation

    Maria José de Freitas Mendes

    2010-06-01

    Full Text Available This paper brings some reflections about the formation of the math teacher that made part of my marsters paper and that aimed to investigate the process of formation of the math teacher. The focus of this study incided at the contributions of teaching practice in the teacher's formation above the new paradigms of formation, as a professional development and as a reflexive teacher. These reflections, from the learning and teaching process and from the meaning of form a teacher analyse the crisis and the restructuration of the teacher's formation and conclude being necessary that in the graduation courses there's a character more practice to the pedagogical formation, making possible for the future teacher to develop attitudes of autonomy, reflexion and investigation

  9. Formation temperatures of thermogenic and biogenic methane

    Stolper, D.A.; Lawson, M.; Davis, C.L.; Ferreira, A.A.; Santos Neto, E. V.; Ellis, G.S.; Lewan, M.D.; Martini, Anna M.; Tang, Y.; Schoell, M.; Sessions, A.L.; Eiler, J.M.

    2014-01-01

    Methane is an important greenhouse gas and energy resource generated dominantly by methanogens at low temperatures and through the breakdown of organic molecules at high temperatures. However, methane-formation temperatures in nature are often poorly constrained. We measured formation temperatures of thermogenic and biogenic methane using a “clumped isotope” technique. Thermogenic gases yield formation temperatures between 157° and 221°C, within the nominal gas window, and biogenic gases yield formation temperatures consistent with their comparatively lower-temperature formational environments (<50°C). In systems where gases have migrated and other proxies for gas-generation temperature yield ambiguous results, methane clumped-isotope temperatures distinguish among and allow for independent tests of possible gas-formation models.

  10. Habit formation, work ethics, and technological progress

    Faria, João Ricardo; León-Ledesma, Miguel A.

    2002-01-01

    Work ethics affects labor supply. This idea is modeled assuming that work is habit forming. This paper introduces working habits in a neoclassical growth model and compares its outcomes with a model without habit formation. In addition, it analyzes the impact of different forms of technical progress. The findings are that i) labor supply in the habit formation case is higher than in the neoclassical case; ii) unlike in the neoclassical case, labor supply in the presence of habit formation wil...

  11. Theoretical Aspects of Enterprise Business Strategy Formation

    Valentinavičius, Stasys

    2009-01-01

    The paper presents interpretations of business strategy concept and analyses strategy planning and formation, models. The concept of business strategy is revised and formulated considering various authors approaches. Analysis of business strategy formation process – steps of development and management, selection of strategy type – is based on presented strategy planning models. The aspects of enterprise business and investment strategy formation, coordination and valuation are analysed. The s...

  12. Formation and behaviour of organic iodine

    Zilliacus, R.; Koukkar, P.; Karjunen, T.; Sjoevall, H.

    2002-01-01

    The report presents experimental studies on the formation of organic iodine in severe reactor accidents. The analyses were performed to evaluate the amount of alkaline chemical needed for effective pH control of containment water during the accidents. The formation of organic iodine in solutions used in the filtered venting system and the absorption of iodine compounds in the solutions were studied. Experiments for the formation of organic iodine on painted surfaces were also performed. (au)

  13. Transient Exciplex Formation Electron Transfer Mechanism

    Michael G. Kuzmin; Irina V. Soboleva; Elena V. Dolotova

    2011-01-01

    Transient exciplex formation mechanism of excited-state electron transfer reactions is analyzed in terms of experimental data on thermodynamics and kinetics of exciplex formation and decay. Experimental profiles of free energy, enthalpy, and entropy for transient exciplex formation and decay are considered for several electron transfer reactions in various solvents. Strong electronic coupling in contact pairs of reactants causes substantial decrease of activation energy relative to that for c...

  14. Negative ion formation and neutralization processes, (1)

    Sugiura, Toshio

    1982-01-01

    This review has been made preliminary for the purpose of contribute to the plasma heating by ''negative ion based neutral beam injection'' in the magnetic confinement fusion reactor. A compilation includes the survey of the general processes of negative ion formation, the data of the cross section of H - ion formation and the neutralization of H - ion, and some of new processes of H - ion formation. The data of cross section are mainly experimental, but partly include the results of theoretical calculation. (author)

  15. Mechanism of anticlinal trap formation

    Kuliev, G.G; Kasimova, S.M; Kulieva, G.Z.

    2002-01-01

    Full text: Geo dynamic development of sedimentary basin in accompanied in different stages by significant changes of stressed states. These changes can cover the upper layers as well as deep inner layers of geological stack. In certain levels, called critical level, in consequence of exhausting the feasibility of slow constant deformation, change of regular structures Equilibrium State and folding formation may occur. In total with horizontal component of geo static pressure and tectonic stress, in both cases these compressive loads may be enough to form folding by means of regular structure Equilibrium State instability loss and change to more stable Equilibrium State with curved structure. In this report there are the results of investigation of given problem within non-classical linearized 3D theoretical geomechanical model. Symmetric and asymmetric forms of change to more stable Equilibrium State when modeling deformed medium in kind of an isotropic and anisotropic material, in case of small elastic deformation were investigated. So, results permit us to conclude that only owing to submersion, different forms of structural curvature may occur in geological stack and that parameters of these structural form-changing are considered more accurate within non-classical linearized 3D geo dynamical model.Analogous results were obtained in case of compressive stress occurrence in consequence of density differentiation of rocks. From the obtains results it follows that Equilibrium State of half-plane in irregular compression proves to be unstable when assigning on free half-plane surface dead as well as tracking loads. The increase of intensity value of different surface loads exerts contrary influence on values of critical loads of stability loss depending on modeling of their character of influence. So, the increase of intensity of dead surface loads leads to decrease, but increase of tracking surface loads leads to increase of equilibrium state loss critical force

  16. STAR FORMATION IN 30 DORADUS

    De Marchi, Guido; Spezzi, Loredana; Sirianni, Marco; Andersen, Morten; Paresce, Francesco; Panagia, Nino; Mutchler, Max; Whitmore, Bradley C.; Bond, Howard; Beccari, Giacomo; Balick, Bruce; Dopita, Michael A.; Frogel, Jay A.; Calzetti, Daniela; Marcella Carollo, C.; Disney, Michael J.; Hall, Donald N. B.; Holtzman, Jon A.; Kimble, Randy A.; McCarthy, Patrick J.

    2011-01-01

    Using observations obtained with the Wide-Field Camera 3 on board the Hubble Space Telescope, we have studied the properties of the stellar populations in the central regions of 30 Dor in the Large Magellanic Cloud. The observations clearly reveal the presence of considerable differential extinction across the field. We characterize and quantify this effect using young massive main-sequence stars to derive a statistical reddening correction for most objects in the field. We then search for pre-main-sequence (PMS) stars by looking for objects with a strong (>4σ) Hα excess emission and find about 1150 of them over the entire field. Comparison of their location in the Hertzsprung-Russell diagram with theoretical PMS evolutionary tracks for the appropriate metallicity reveals that about one-third of these objects are younger than ∼4 Myr, compatible with the age of the massive stars in the central ionizing cluster R 136, whereas the rest have ages up to ∼30 Myr, with a median age of ∼12 Myr. This indicates that star formation has proceeded over an extended period of time, although we cannot discriminate between an extended episode and a series of short and frequent bursts that are not resolved in time. While the younger PMS population preferentially occupies the central regions of the cluster, older PMS objects are more uniformly distributed across the field and are remarkably few at the very center of the cluster. We attribute this latter effect to photo-evaporation of the older circumstellar disks caused by the massive ionizing members of R 136.

  17. Processes and problems in secondary star formation

    Klein, R.I.; Whitaker, R.W.; Sandford, M.T. II.

    1984-03-01

    Recent developments relating the conditions in molecular clouds to star formation triggered by a prior stellar generation are reviewed. Primary processes are those that lead to the formation of a first stellar generation. The secondary processes that produce stars in response to effects caused by existing stars are compared and evaluated in terms of the observational data presently available. We discuss the role of turbulence to produce clumpy cloud structures and introduce new work on colliding inter-cloud gas flows leading to non-linear inhomogeneous cloud structures in an intially smooth cloud. This clumpy morphology has important consequences for secondary formation. The triggering processes of supernovae, stellar winds, and H II regions are discussed with emphasis on the consequences for radiation driven implosion as a promising secondary star formation mechanism. Detailed two-dimensional, radiation-hydrodynamic calculations of radiation driven implosion are discussed. This mechanism is shown to be highly efficient in synchronizing the formation of new stars in congruent to 1-3 x 10 4 years and could account for the recent evidence for new massive star formation in several UCHII regions. It is concluded that, while no single theory adequately explains the variety of star formation observed, a uniform description of star formation is likely to involve several secondary processes. Advances in the theory of star formation will require multiple dimensional calculations of coupled processes. The important non-linear interactions include hydrodynamics, radiation transport, and magnetic fields

  18. Processes and problems in secondary star formation

    Klein, R.I.; Whitaker, R.W.; Sandford, M.T. II

    1985-01-01

    Recent developments relating the conditions in molecular clouds to star formation triggered by a prior stellar generation are reviewed. Primary processes are those that lead to the formation of a first stellar generation. The secondary processes that produce stars in response to effects caused by existing stars are compared and evaluated in terms of observational data presently available. We discuss the role of turbulence to produce clumpy cloud structures and introduce new work on colliding intercloud gas flows leading to nonlinear inhomogeneous cloud structures in an initially smooth cloud. This clumpy morphology has important consequences for secondary formation. The triggering processes of supernovae, stellar winds, and H II regions are discussed with emphasis on the consequences for radiation-driven implosion as a promising secondary star formation mechanism. Detailed two-dimensional, radiation-hydrodynamic calculations of radiation-driven implosion are discussed. This mechanism is shown to be highly efficient in synchronizing the formation of new stars in -- 1-3 x 10/sup 4/ yr and could account for the recent evidence for new massive star formation in several ultracompact H II regions. It is concluded that, while no single theory adequately explains the variety of star formation observed, a uniform description of star formation is likely to involve several secondary processes. Advances in the theory of star formation will require multi-dimensional calculations of coupled processes. Important nonlinear interactions include hydrodynamics, radiation transport, and magnetic fields

  19. Formation of the First Stars and Blackholes

    Yoshida, Naoki

    2018-05-01

    Cosmic reionization is thought to be initiated by the first generation of stars and blackholes. We review recent progress in theoretical studies of early structure formation. Cosmic structure formation is driven by gravitational instability of primeval density fluctuations left over from Big Bang. At early epochs, there are baryonic streaming motions with significant relative velocity with respect to dark matter. The formation of primordial gas clouds is typically delayed by the streaming motions, but then physical conditions for the so-called direct collapse blackhole formation are realized in proto-galactic halos. We present a promising model in which intermediate mass blackholes are formed as early as z = 30.

  20. The NeXus data format

    Könnecke, Mark; Akeroyd, Frederick A.; Osborn, Raymond; Peterson, Peter F.; Richter, Tobias; Suzuki, Jiro; Watts, Benjamin; Wintersberger, Eugen; Wuttke, Joachim; Bernstein, Herbert J.; Brewster, Aaron S.; Campbell, Stuart I.; Clausen, Björn; Cottrell, Stephen; Hoffmann, Jens Uwe

    2015-01-01

    NeXus is an effort by an international group of scientists to define a common data exchange and archival format for neutron, X-ray and muon experiments. NeXus is built on top of the scientific data format HDF5 and adds domain-specific rules for organizing data within HDF5 files, in addition to a dictionary of well defined domain-specific field names. The NeXus data format has two purposes. First, it defines a format that can serve as a container for all relevant data associated with a beamlin...

  1. An anti vimentin antibody promotes tube formation

    Jørgensen, Mathias Lindh; Møller, Carina Kjeldahl; Rasmussen, Lasse

    2017-01-01

    antibody technology, promotes tube formation of endothelial cells in a 2D matrigel assay. By binding vimentin, the antibody increases the tube formation by 21% after 5 hours of incubation. Addition of the antibody directly to cultured endothelial cells does not influence endothelial cell migration...... or proliferation. The enhanced tube formation can be seen for up to 10 hours where after the effect decreases. It is shown that the antibody-binding site is located on the coil 2 domain of vimentin. To our knowledge this is the first study that demonstrates an enhanced tube formation by binding vimentin in a 2D...

  2. Heating systems for heating subsurface formations

    Nguyen, Scott Vinh [Houston, TX; Vinegar, Harold J [Bellaire, TX

    2011-04-26

    Methods and systems for heating a subsurface formation are described herein. A heating system for a subsurface formation includes a sealed conduit positioned in an opening in the formation and a heat source. The sealed conduit includes a heat transfer fluid. The heat source provides heat to a portion of the sealed conduit to change phase of the heat transfer fluid from a liquid to a vapor. The vapor in the sealed conduit rises in the sealed conduit, condenses to transfer heat to the formation and returns to the conduit portion as a liquid.

  3. Heating tar sands formations to visbreaking temperatures

    Karanikas, John Michael [Houston, TX; Colmenares, Tulio Rafael [Houston, TX; Zhang, Etuan [Houston, TX; Marino, Marian [Houston, TX; Roes, Augustinus Wilhelmus Maria [Houston, TX; Ryan, Robert Charles [Houston, TX; Beer, Gary Lee [Houston, TX; Dombrowski, Robert James [Houston, TX; Jaiswal, Namit [Houston, TX

    2009-12-22

    Methods for treating a tar sands formation are described herein. Methods may include heating at least a section of a hydrocarbon layer in the formation from a plurality of heaters located in the formation. The heat may be controlled so that at least a majority of the section reaches an average temperature of between 200.degree. C. and 240.degree. C., which results in visbreaking of at least some hydrocarbons in the section. At least some visbroken hydrocarbon fluids may be produced from the formation.

  4. Towards the Rosetta Stone of planet formation

    Schmidt T.O.B.

    2011-02-01

    Full Text Available Transiting exoplanets (TEPs observed just ~10 Myrs after formation of their host systems may serve as the Rosetta Stone for planet formation theories. They would give strong constraints on several aspects of planet formation, e.g. time-scales (planet formation would then be possible within 10 Myrs, the radius of the planet could indicate whether planets form by gravitational collapse (being larger when young or accretion growth (being smaller when young. We present a survey, the main goal of which is to find and then characterise TEPs in very young open clusters.

  5. New Particle Formation Study Final Campaign Report

    Smith, JN; McMurry, PH [University of Minnesota

    2015-01-01

    The scientific foci of the New Particle Formation Study were the formation and evolution of atmospheric aerosols and the impacts of newly formed particles on cloud processes. Specifically, we planned to: (1) to identify the species and mechanisms responsible for the initial steps of new particle formation, i.e., the formation of thermodynamically stable clusters; (2) investigate the role of acid-base chemistry in new particle growth through measurements of ammonia and amines as well as organic and inorganic acids in both atmospheric nanoparticles and the gas phase; (3) investigate the contribution of other surface area or volume-controlled processes to nanoparticle formation and growth; (4) create a comprehensive dataset related to new particle formation and growth that can be used as input for our own thermodynamic models as well as the modeling efforts by our Department of Energy (DOE) Aerosol Life Cycle working group collaborators; (5) characterize the increase of the number and activity of cloud condensation nuclei (CCN) due to particle formation and growth; (6) determine the regional extent of new particle formation to address the role that atmospheric transport plays in determining the impacts, if any, of new particle formation on cloud number and properties.

  6. Probes of Cosmic Star Formation History

    I summarize X-ray diagnostic studies of cosmic star formation history in terms of evolutionary schemes for X-ray binary evolution in normal galaxies with evolving star formation. Deep X-ray imaging studies by Chandra and XMM-Newton are now beginning to constrain both the X-ray luminosity evolution of galaxies and the ...

  7. Network Formation under the Threat of Disruption

    Hoyer, B.

    2013-01-01

    The studies in this thesis are focused on the impact the presence of a network disruptor has on network formation models. In particular, we build two theoretical models to study the effect of network disruption on network formation and test the effect network disruption has on equilibrium selection

  8. Combinations of partners’ joint venture formation motives

    Klijn, E.; Reuer, J.J.; Buckley, P.J.; Glaister, K.W.

    2011-01-01

    Purpose – Prior research on joint venture (JV) formation often examines a single focal firm and assumes it has a single motive for collaboration. This study seeks to investigate how formation motives of partner firms are symmetrically coupled. It considers motives in the context of different

  9. General certification procedure of formation organizations

    Int. At. Energy Agency, Wien

    2002-01-01

    This document presents the procedure dealing with the certification of formation organizations dispensing the formation and the risks prevention to the personnel of A or B category in nuclear facilities. This certification proves the organization ability to satisfy the ''F'' specification of the CEFRI. (A.L.B.)

  10. Problems of Kazakh Literary Criticism Formation

    Zhandos Smagulov

    2013-01-01

    Full Text Available Тhe article is concerned with the problem of scientific research of Kazakh literature formation in national science. Kazakh literature, having long history of formation is classified by periods. Besides, the article thoroughly considers the principles of the study of methodology, theory, history of spiritual heritage in Kazakh literary criticism

  11. The early ISM and galaxy formation

    White, Simon D. M.

    1990-01-01

    Current ideas about galaxy formation are reviewed, with particular attention to when and how it occurred, and what it might have looked like. It is argued that galaxy formation is more recent than originally predicted. Suggestions are presented as to how current observations of distant objects may be interpreted within the cold dark matter theory for the origin of structure.

  12. 25 CFR 82.6 - Petition format.

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Petition format. 82.6 Section 82.6 Indians BUREAU OF... REORGANIZED UNDER FEDERAL STATUTE AND OTHER ORGANIZED TRIBES § 82.6 Petition format. Petitions may consist of... of a petition must set forth at least a summary of the objectives of the petitioners and must show...

  13. A Decentralized Approach to Formation Flight Routing

    Visser, H.G.; Lopes dos Santos, Bruno F.; Verhagen, C.M.A.

    2016-01-01

    This paper describes the development of an optimization-based cooperative planning system for the efficient routing and scheduling of flight formations. This study considers the use of formation flight as a means to reduce the overall fuel consumption of civil aviation in long-haul operations. It

  14. Unit Monitors Manchester-Format Data Buses

    Amador, Jose J.

    1994-01-01

    Circuit card converts data signals into convenient hexadecimal form for troubleshooting. Bus-monitoring unit converts data signals from Manchester II format used on data bus into hexadecimal format. Monitoring circuit causes hexadecimal words to display on video terminal, where test engineer compares them with hexadecimal records for troubleshooting. Circuit monitors one bus or two buses simultaneously.

  15. Distributed formation control for autonomous robots

    Garcia de Marina Peinado, Hector Jesús

    2016-01-01

    This thesis addresses several theoretical and practical problems related to formation-control of autonomous robots. Formation-control aims to simultaneously accomplish the tasks of forming a desired shape by the robots and controlling their coordinated collective motion. This kind of robot

  16. Spur Reaction Model of Positronium Formation

    Mogensen, O. E.

    1974-01-01

    A new model of positronium (Ps) formation is proposed. Positronium is assumed to be formed by a reaction between a positron and an electron in the positron spur. Ps formation must compete with electron‐ion recombination and electron or positron reactions with solvent molecules and scavenger...

  17. Hydrocarbon formation mechanism during uranium monocarbide hydrolysis

    Ermolaev, M.I.; Tishchenko, G.V.

    1979-01-01

    The hydrolysis of uranium monocarbide in oxidative media and in the presence of excessive hydrogen in statu nascendi has been investigated. It was found that oxydants promote the formation of elementary carbon, while in the presence of hydrogen the yield of light C-C hydrocarbons increases. EPR data confirm the radical mechanism of hydrocarbons formation during the decomposition of uranium monocarbide

  18. Formation and evolution of compact binaries

    Sluijs, Marcel Vincent van der

    2006-01-01

    In this thesis we investigate the formation and evolution of compact binaries. Chapters 2 through 4 deal with the formation of luminous, ultra-compact X-ray binaries in globular clusters. We show that the proposed scenario of magnetic capture produces too few ultra-compact X-ray binaries to explain

  19. Enhancing the Lecture: Revitalizing the Traditional Format.

    Bonwell, Charles C.

    1996-01-01

    The traditional lecture format of college courses can be enhanced by including active learning designed to further course goals of learning knowledge, developing skills, or fostering attitudes. Techniques suggested include using pauses, short writing periods, think-pair-share activities, formative quizzes, lecture summaries, and several assessment…

  20. Stone Formation in the Infected Pediatric Enterocystoplasty

    R.B. Mathoera (Rejiv)

    2003-01-01

    markdownabstract__Abstract__ Proteus mirabilis is one of the most frequent bacterial agents that can induce infection stone formation by urease production. In recent years the influence of Proteus mirabilis on stone formation in enterocystoplasties has been primarily related to the presence of

  1. Chemostratigraphy of Neoproterozoic Banded Iron Formation (BIF)

    Gaucher, Claudio; Sial, Alcides N.; Frei, Robert

    2015-01-01

    Sawawin BIF (Saudi Arabia), and the Jucurutu Formation of the Seridó Belt (NE Brazil). Lake Superior type BIFs are represented by the Tonian Shilu Group (South China) and the late Ediacaran Arroyo del Soldado Group (Yerbal and Cerro Espuelitas formations, Uruguay). Useful chemostratigraphic tools...

  2. Computer-based feedback in formative assessment

    van der Kleij, Fabienne

    2013-01-01

    Formative assessment concerns any assessment that provides feedback that is intended to support learning and can be used by teachers and/or students. Computers could offer a solution to overcoming obstacles encountered in implementing formative assessment. For example, computer-based assessments

  3. Harnessing Collaborative Annotations on Online Formative Assessments

    Lin, Jian-Wei; Lai, Yuan-Cheng

    2013-01-01

    This paper harnesses collaborative annotations by students as learning feedback on online formative assessments to improve the learning achievements of students. Through the developed Web platform, students can conduct formative assessments, collaboratively annotate, and review historical records in a convenient way, while teachers can generate…

  4. Cellular chain formation in Escherichia coli biofilms

    Vejborg, Rebecca Munk; Klemm, Per

    2009-01-01

    ; type I fimbriae expression significantly reduced cellular chain formation, presumably by steric hindrance. Cellular chain formation did not appear to be specific to E coli K-12. Although many urinary tract infection (UTI) isolates were found to form rather homogeneous, flat biofilms, three isolates...

  5. XML-based DICOM data format.

    Yu, Cong; Yao, Zhihong

    2010-04-01

    To enhance the readability, improve the structure, and facilitate the sharing of digital imaging and communications in medicine (DICOM) files, this research proposed one kind of XML-based DICOM data format. Because XML Schema offers great flexibility for expressing constraints on the content model of elements, we used it to describe the new format, thus making it consistent with the one originally defined by DICOM. Meanwhile, such schemas can be used in the creation and validation of the XML-encoded DICOM files, acting as a standard for data transmission and sharing on the Web. Upon defining the new data format, we started with representing a single data element and further improved the whole data structure with the method of modularization. In contrast to the original format, the new one possesses better structure without loss of related information. In addition, we demonstrated the application of XSLT and XQuery. All of the advantages mentioned above resulted from this new data format.

  6. Exploring the value of usability feedback formats

    Nørgaard, Mie; Hornbæk, Kasper Anders Søren

    2009-01-01

    The format used to present feedback from usability evaluations to developers affects whether problems are understood, accepted, and fixed. Yet, little research has investigated which formats are the most effective. We describe an explorative study where three developers assess 40 usability findings...... presented using five feedback formats. Our usability findings comprise 35 problems and 5 positive comments. Data suggest that feedback serves multiple purposes. Initially, feedback must convince developers about the relevance of a problem and convey an understanding of this. Feedback must next be easy...... working with the feedback to address the usability problems, there were no significant differences among the developers' ratings of the value of the different formats. This suggests that all of the formats may serve equally well as reminders in later stages of working with usability problems...

  7. Teacher perspectives about using formative assessment

    Evans, Robert Harry; Clesham, Rose; Dolin, Jens

    2018-01-01

    This chapter examines three different classroom teacher perspectives when using ASSIST-ME project formative assessment methods as described in the introductory chapter. The first ‘teacher perspective’ is about changes in teacher self-efficacies while using formative assessment methods as monitored...... by a pre- and post-teacher questionnaire. Teachers who tried the unfamiliar formative methods of assessment (see introductory book chapter for these methods) as well as their colleagues who did not were surveyed. The second ‘teacher perspective’ examines changes in teachers’ subjective theories while...... trying project-specific formative assessment methods in Czech Republic. Analyses are done through case studies and interviews. The final part of the chapter looks at teacher perspectives while using an Internet-based application to facilitate formative assessment. The teacher use of the application...

  8. Analysis of constituents of earth formations

    Hertzog, R.C.; Grau, J.A.

    1981-01-01

    The composition of an earth formation is investigated by repetitively irradiating the formation with bursts of neutrons from a source and measuring an energy spectrum of the scattering gamma rays resulting from such irradiation e.g. by photomultiplier or solid state detector. The measured spectrum is thereafter analyzed by comparing it with a composite spectrum, made up of standard spectra, measured in a controlled environment, of constituents postulated to comprise the formation. As a result of such analysis, the proportions of the postulated constituents in the formation are determined. Since the measured spectrum is subject to degradation due to changes in the resolution of the detector, a filtering arrangement effects modification of the standard spectra in a manner which compensates for the changes in the detector and thereby provides for a more accurate determination of the constituents of the formation. Temperature is measured by sensor to compensate for temperature dependence of detector resolution. (author)

  9. Network Configuration Analysis for Formation Flying Satellites

    Knoblock, Eric J.; Wallett, Thomas M.; Konangi, Vijay K.; Bhasin, Kul B.

    2001-01-01

    The performance of two networks to support autonomous multi-spacecraft formation flying systems is presented. Both systems are comprised of a ten-satellite formation, with one of the satellites designated as the central or 'mother ship.' All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/EP over ATM protocol architecture within the formation, and the second system uses the IEEE 802.11 protocol architecture within the formation. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IP queuing delay, IP queue size and IP processing delay at the mother ship as well as end-to-end delay for both systems. In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

  10. FORMATIVE ASSESSMENT IN EFL CLASSROOM PRACTICES

    Ida Ayu Made Sri Widiastuti

    2017-03-01

    Full Text Available This study investigated the challenges and opportunities of formative assessment in EFL classes. It made use of qualitative research design by using indepth interviews to collect the required data. Three teachers and three students were involved as research participants in this study and they were intensively interviewed to get valid and reliable data regarding their understanding of formative assessment and the follow up actions they took after implementing formative assessment. The results of this study showed that the English teachers were found not to take appropriate follow up actions due to their low understanding of formative assessment. The teachers’ understanding could influence their ability in deciding the actions. This study indicates that EFL teachers need urgent further intensive training on the appropriate implementation of formative assessment and how follow up actions should be integrated into classroom practices

  11. THE SPECIAL STATUS OF EXOGENOUS WORD-FORMATION WITHIN THE GERMAN WORD-FORMATION SYSTEM

    Zhilyuk Sergey Aleksandrovich

    2014-01-01

    The article presents the properties of exogenous word-formation system taking into account the existence of two word-formation systems in modern German. On the basis of foreign research which reveal modern trends in German word-formation connected with the internationalization and the development of new European Latin language. The author defines key features of exogenous word-formation, i.e. foreign origin of wordformation units, unmotivated units, unmotivated interchange in base and affixes...

  12. Maggot excretions inhibit biofilm formation on biomaterials.

    Cazander, Gwendolyn; van de Veerdonk, Mariëlle C; Vandenbroucke-Grauls, Christina M J E; Schreurs, Marco W J; Jukema, Gerrolt N

    2010-10-01

    Biofilm-associated infections in trauma surgery are difficult to treat with conventional therapies. Therefore, it is important to develop new treatment modalities. Maggots in captured bags, which are permeable for larval excretions/secretions, aid in healing severe, infected wounds, suspect for biofilm formation. Therefore we presumed maggot excretions/secretions would reduce biofilm formation. We studied biofilm formation of Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella oxytoca, Enterococcus faecalis, and Enterobacter cloacae on polyethylene, titanium, and stainless steel. We compared the quantities of biofilm formation between the bacterial species on the various biomaterials and the quantity of biofilm formation after various incubation times. Maggot excretions/secretions were added to existing biofilms to examine their effect. Comb-like models of the biomaterials, made to fit in a 96-well microtiter plate, were incubated with bacterial suspension. The formed biofilms were stained in crystal violet, which was eluted in ethanol. The optical density (at 595 nm) of the eluate was determined to quantify biofilm formation. Maggot excretions/secretions were pipetted in different concentrations to (nonstained) 7-day-old biofilms, incubated 24 hours, and finally measured. The strongest biofilms were formed by S. aureus and S. epidermidis on polyethylene and the weakest on titanium. The highest quantity of biofilm formation was reached within 7 days for both bacteria. The presence of excretions/secretions reduced biofilm formation on all biomaterials. A maximum of 92% of biofilm reduction was measured. Our observations suggest maggot excretions/secretions decrease biofilm formation and could provide a new treatment for biofilm formation on infected biomaterials.

  13. Formation Control for the MAXIM Mission

    Luquette, Richard J.; Leitner, Jesse; Gendreau, Keith; Sanner, Robert M.

    2004-01-01

    Over the next twenty years, a wave of change is occurring in the space-based scientific remote sensing community. While the fundamental limits in the spatial and angular resolution achievable in spacecraft have been reached, based on today s technology, an expansive new technology base has appeared over the past decade in the area of Distributed Space Systems (DSS). A key subset of the DSS technology area is that which covers precision formation flying of space vehicles. Through precision formation flying, the baselines, previously defined by the largest monolithic structure which could fit in the largest launch vehicle fairing, are now virtually unlimited. Several missions including the Micro-Arcsecond X-ray Imaging Mission (MAXIM), and the Stellar Imager will drive the formation flying challenges to achieve unprecedented baselines for high resolution, extended-scene, interferometry in the ultraviolet and X-ray regimes. This paper focuses on establishing the feasibility for the formation control of the MAXIM mission. MAXIM formation flying requirements are on the order of microns, while Stellar Imager mission requirements are on the order of nanometers. This paper specifically addresses: (1) high-level science requirements for these missions and how they evolve into engineering requirements; and (2) the development of linearized equations of relative motion for a formation operating in an n-body gravitational field. Linearized equations of motion provide the ground work for linear formation control designs.

  14. Influence of fluorosurfactants on hydrate formation rates

    Kim, C.U.; Jeong, K.E.; Chae, H.J.; Jeong, S.Y. [Korea Reasearch Inst. of Chemical Technology, Alternative Chemicals/Fuel Research Center, Yuseong-Gu, Daejon (Korea, Republic of)

    2008-07-01

    Gas hydrates, or clathrates, are ice-like solids that forms when natural gas is in contact with liquid water or ice under high pressure and low temperature. There is significant interest in studying the storage and transportation of gas in the form of hydrates. However, a critical problem impacting the industrial application of gas hydrates for storage and transportation of natural gas is the slow formation rate of natural gas hydrate. Researchers have previously reported on the promotion effect of some additives on gas hydrate formation and hydrate gas content. Fluorosurfactants are significantly superior to nonfluorinated surfactants in wetting action, as well as stability in harsh environments, both thermal and chemical. This paper discussed an experimental investigation into the effects of fluorosurfactants with different ionic types on the formation of methane hydrate. The surfactants used were FSN-100 of DuPont Zonyl as non-ionic surfactant and FC-143 of DuPont as anionic surfactant. The paper discussed the experimental apparatus for methane hydrate formation. It also discussed hydrate formation kinetics and the series of hydrate formation experiments that were conducted in the presence of fluorosurfactants. Last, the paper explored the results of the study. It was concluded that anionic fluorosurfactant of FC-143 had a better promoting effect on methane hydrate formation compared with nonionic surfactant of FSN-100. 8 refs., 2 tabs., 2 figs.

  15. Planetesimal formation starts at the snow line

    Drążkowska, J.; Alibert, Y.

    2017-12-01

    Context. The formation stage of planetesimals represents a major gap in our understanding of the planet formation process. Late-stage planet accretion models typically make arbitrary assumptions about planetesimal and pebble distribution, while dust evolution models predict that planetesimal formation is only possible at some orbital distances. Aims: We wish to test the importance of the water snow line in triggering the formation of the first planetesimals during the gas-rich phase of a protoplanetary disk, when cores of giant planets have to form. Methods: We connected prescriptions for gas disk evolution, dust growth and fragmentation, water ice evaporation and recondensation, the transport of both solids and water vapor, and planetesimal formation via streaming instability into a single one-dimensional model for protoplanetary disk evolution. Results: We find that processes taking place around the snow line facilitate planetesimal formation in two ways. First, because the sticking properties between wet and dry aggregates change, a "traffic jam" inside of the snow line slows the fall of solids onto the star. Second, ice evaporation and outward diffusion of water followed by its recondensation increases the abundance of icy pebbles that trigger planetesimal formation via streaming instability just outside of the snow line. Conclusions: Planetesimal formation is hindered by growth barriers and radial drift and thus requires particular conditions to take place. The snow line is a favorable location where planetesimal formation is possible for a wide range of conditions, but not in every protoplanetary disk model, however. This process is particularly promoted in large cool disks with low intrinsic turbulence and an increased initial dust-to-gas ratio. The movie attached to Fig. 3 is only available at http://www.aanda.org

  16. Biofilm formation in a hot water system

    Bagh, L.K.; Albrechtsen, Hans-Jørgen; Arvin, Erik

    2002-01-01

    The biofilm formation rate was measured in situ in a hot water system in an apartment building by specially designed sampling equipment, and the net growth of the suspended bacteria was measured by incubation of water samples with the indigeneous bacteria. The biofilm formation rate reached......, in the sludge, or in the water from the distribution system was negligible. This indicated that bacterial growth took place on the inner surfaces in the hot water system and biofilm formation and detachment of bacteria could account for most of the suspended bacteria actually measured in hot water. Therefore...

  17. Formation of nuclear security culture in Ukraine

    V. I. Gavryliuk

    2014-06-01

    Full Text Available Issues of nuclear security culture formation are considered in the article. Information on establishing and ac-tivity of Working Group for formation and development of nuclear security culture being held during 2010 – 2013 is given. An issue of regulation of activity on formation and development of nuclear security culture is il-lustrated. Analysis of the survey results regarding efficiency assessment of the work aimed to form and develop of nuclear security culture of nuclear facilities is carried out. The results show that the nuclear security culture of the most of nuclear facilities in Ukraine has been formed and is at the stage of development.

  18. Formation of nuclear security culture in Ukraine

    Gavrilyuk, V.Yi.; Gavrilyuk-Burakova, A.V.; Drapej, S.S.; Parkhomenko, V.V.; Proskuryin, D.V.; Romanova, O.P.

    2014-01-01

    Issues of nuclear security culture formation are considered in the article. Information on establishing and activity of Working Group for formation and development of nuclear security culture being held during 2010 - 2013 is given. An issue of regulation of activity on formation and development of nuclear security culture is illustrated. Analysis of the survey results regarding efficiency assessment of the work aimed to form and develop of nuclear security culture of nuclear facilities is carried out. The results show that the nuclear security culture of the most of nuclear facilities in Ukraine has been formed and is at the stage of development

  19. Time-Dependent Dust Formation in Novae

    Kyung-Won Suh

    1991-06-01

    Full Text Available The dust formation processes in novae are investigated with close attention to recent infrared observations. Using mainly the classical nucleation theory, we have calculated the time scales of dust formation and growth in the environments of novae. Those time scales roughly resemble the typical observations. We have classified the dust-forming novae into three classes according to their explosion properties and the thermodynamic properties of dust grains. Oxygen grains from much later than carbon grains because of their thermodynamic properties. The effect of grain formation to the efficiency of stellar winds to drive the material outward is tested with newly obtained Planck mean values of dust grains.

  20. Formation of adduct of cerium (4) thenoyltrifluoroacetonate

    Anyfrieva, S.I.; Polyakova, G.V.; Snezhko, N.I.; Pechurova, N.I.; Martynenko, L.I.; Spitsyn, V.I.

    1981-01-01

    Adduct formation of thenoyltrifluoroacetonate of Ce(4) [Ce(TTFA) 4 ] with seven nitrogen- and oxygen-containing donor additional ligands is studied using the methods of IR-spectroscopy, derivatography, X-ray phase analysis. The presence of formation of Ce(TTFA) 4 adducts with phosphorus-containing additional ligands tributyl phosphate (TBP), trioctylphosphine oxide (TOPO), triphenylphosphine oxide (TPPO); α, α'-dipyridyl (Dipy) and o-phenanthroline (Phen) is established. The adduct Ce(TTFA) 4 stable to reduction is formed with Dipy, and in the case of Phen, TBP, TOPO, TPPO in the process of adduct formation the reduction of Ce(4) to Ce(3) takes place [ru

  1. Carbon nanotube formation by laser direct writing

    Wu, Y.-T.; Su, H.-C.; Tsai, C.-M.; Liu, K.-L.; Chen, G.-D.; Huang, R.-H.; Yew, T.-R.

    2008-01-01

    This letter presents carbon nanotube (CNT) formation by laser direct writing using 248 nm KrF excimer pulsed laser in air at room temperature, which was applied to irradiate amorphous carbon (a-C) assisted by Ni catalysts underneath for the transformation of carbon species into CNTs. The CNTs were synthesized under appropriate combination of laser energy density and a-C thickness. The growth mechanism and key parameters to determine the success of CNT formation were also discussed. The demonstration of the CNT growth by laser direct writing in air at room temperature opens an opportunity of in-position CNT formation at low temperatures

  2. Distributed formation tracking using local coordinate systems

    Yang, Qingkai; Cao, Ming; Garcia de Marina, Hector

    2018-01-01

    This paper studies the formation tracking problem for multi-agent systems, for which a distributed estimator–controller scheme is designed relying only on the agents’ local coordinate systems such that the centroid of the controlled formation tracks a given trajectory. By introducing a gradient...... descent term into the estimator, the explicit knowledge of the bound of the agents’ speed is not necessary in contrast to existing works, and each agent is able to compute the centroid of the whole formation in finite time. Then, based on the centroid estimation, a distributed control algorithm...

  3. Extrasolar planets formation, detection and dynamics

    Dvorak, Rudolf

    2008-01-01

    This latest, up-to-date resource for research on extrasolar planets covers formation, dynamics, atmospheres and detection. After a look at the formation of giant planets, the book goes on to discuss the formation and dynamics of planets in resonances, planets in double stars, atmospheres and habitable zones, detection via spectra and transits, and the history and prospects of ESPs as well as satellite projects.Edited by a renowned expert in solar system dynamics with chapters written by the leading experts in the method described -- from the US and Europe -- this is an ideal textbook for g

  4. Emissions and dioxins formation from waste incinerators

    Carbone, A.I.; Zagaroli, M.

    1989-01-01

    This paper describes current knowledge on dioxins formation and emission from waste incinerators. The pertinent Italian law and effects on man health are dealt with, too. The picture of existing municipal incinerators is presented concerning both the actual emission levels and the monitored levels in the environment. Sampling and analysis systems of these organic chlorinated micro-pollutants and current theories on precursors, formation mechanisms, and influence of different parameters are also described. The last section deals with some of the techniques that can be used to reduce dioxins formation and emission from municipal incinerators. (author)

  5. Promoting proximal formative assessment with relational discourse

    Scherr, Rachel E.; Close, Hunter G.; McKagan, Sarah B.

    2012-02-01

    The practice of proximal formative assessment - the continual, responsive attention to students' developing understanding as it is expressed in real time - depends on students' sharing their ideas with instructors and on teachers' attending to them. Rogerian psychology presents an account of the conditions under which proximal formative assessment may be promoted or inhibited: (1) Normal classroom conditions, characterized by evaluation and attention to learning targets, may present threats to students' sense of their own competence and value, causing them to conceal their ideas and reducing the potential for proximal formative assessment. (2) In contrast, discourse patterns characterized by positive anticipation and attention to learner ideas increase the potential for proximal formative assessment and promote self-directed learning. We present an analysis methodology based on these principles and demonstrate its utility for understanding episodes of university physics instruction.

  6. Right timing in formative program evaluation.

    Hall, Jori; Freeman, Melissa; Roulston, Kathy

    2014-08-01

    Since many educational researchers and program developers have limited knowledge of formative evaluation, formative data may be underutilized during the development and implementation of an educational program. The purpose of this article is to explain how participatory, responsive, educative, and qualitative approaches to formative evaluation can facilitate a partnership between evaluators and educational researchers and program managers to generate data useful to inform program implementation and improvement. This partnership is critical, we argue, because it enables an awareness of when to take appropriate action to ensure successful educational programs or "kairos". To illustrate, we use examples from our own evaluation work to highlight how formative evaluation may facilitate opportune moments to (1) define the substance and purpose of a program, (2) develop understanding and awareness of the cultural interpretations of program participants, and (3) show the relevance of stakeholder experiences to program goals. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Septum formation of the lateral ventricles

    Celik, Hakan H.; Aldur, Mustafa M.; Tatar, I.; Tascioglu, A.B.

    2005-01-01

    In an MRI study examining anomalies of the septum pellucidum in 505 cases, we detected bilateral septum formation of the lateral ventricles in a 17-months-old-baby. In this study, we evaluate 505 (242 males and 263 females) patients referred to the Emaray Imaging Center, Ankara, Turkey with various prediagnoses. We specially selected all the cases from a non-psychotic population. We obtained MRI scans on a 1-Tesla imager (Picker International, Highland Heights, Ohio, USA), with slices of 5 and 6 mm thickness. In the axial and coronal sections, we observed septum formation laterally between the anterior horn and the ventricular body of the lateral ventricles. Radio opaque septum formations started from the caudate nucleus and stretched to the genu of the corpus callosum. There was a second septum formation between the posterior horn and the ventricular body of the right lateral ventricle. It started from the caudate nucleus and stretched to the cavum vergae. (author)

  8. Physics of star formation in galaxies

    Palla, F

    2002-01-01

    Begining with a historical introduction, ""Star Formation: The Early History"", this text then presents two long articles on ""Pre-Main-Sequence Evolution of Stars and Young Clusters"" and ""Observations of Young Stellar Objects"".

  9. Levels of Elitological Formation of Personality

    N B Karabushchenko

    2011-12-01

    Full Text Available The article describes the main stages of the elitological formation of a personality: the basic level of elitological knowledge, elitological literacy, elitological competence, elitological culture, elite-oriented outlook.

  10. Microbial processes in banded iron formation deposition

    Posth, Nicole; Konhauser, Kurt; Kappler, Andreas

    2013-01-01

    , remains unresolved. Evidence of an anoxic Earth with only localized oxic areas until the Great Oxidation Event ca 2·45 to 2·32 Ga makes the investigation of O2-independent mechanisms for banded iron formation deposition relevant. Recent studies have explored the long-standing proposition that Archean......Banded iron formations have been studied for decades, particularly regarding their potential as archives of the Precambrian environment. In spite of this effort, the mechanism of their deposition and, specifically, the role that microbes played in the precipitation of banded iron formation minerals...... banded iron formations may have been formed, and diagenetically modified, by anaerobic microbial metabolisms. These efforts encompass a wide array of approaches including isotope, ecophysiological and phylogeny studies, molecular and mineral marker analysis, and sedimentological reconstructions. Herein...

  11. Formation of soap bubbles by gas jet

    Zhou, Maolei; Li, Min; Chen, Zhiyuan; Han, Jifeng; Liu, Dong

    2017-12-01

    Soap bubbles can be easily generated by various methods, while their formation process is complicated and still worth studying. A model about the bubble formation process was proposed in the study by Salkin et al. [Phys. Rev. Lett. 116, 077801 (2016)] recently, and it was reported that the bubbles were formed when the gas blowing velocity was above one threshold. However, after a detailed study of these experiments, we found that the bubbles could be generated in two velocity ranges which corresponded to the laminar and turbulent gas jet, respectively, and the predicted threshold was only effective for turbulent gas flow. The study revealed that the bubble formation was greatly influenced by the aerodynamics of the gas jet blowing to the film, and these results will help to further understand the formation mechanism of the soap bubble as well as the interaction between the gas jet and the thin liquid film.

  12. The Role of Emotions in Delusion Formation

    Smurzyńska Adrianna

    2016-12-01

    Full Text Available The text concerns the role of emotions in delusion formation. Provided are definitions from DSM-V and DSM-IV-R and the problems found in those definitions. One of them, the problem of delusion formation, is described when providing cognitive theories of delusions. The core of the paper is a presentation of the emotional and affective disorders in delusions, especially Capgras delusion and Cotard delusion. The author provides a comparison of the kinds of delusions and the conclusions taken from neuroimaging studies. As a result of the fact that an explanation of delusion formation focusing on emotional problems turns out to be insufficient, the author provides examples of the reasoning impairments which coexist with them. At the end of the article, some hypotheses are proposed concerning the role of emotions and reasoning in delusion formation and the relation between belief disorders and emotional disorders.

  13. Optimized Lift for Autonomous Formation Flight

    National Aeronautics and Space Administration — Experimental in-flight evaluations have demonstrated that the concept of formation flight can reduce fuel consumption of trailing aircraft by 10 percent. Armstrong...

  14. MP3 the meaning of a format

    Sterne, Jonathan

    2012-01-01

    Jonathan Sterne shows that understanding the historical meaning of the MP3, the world's most common format for recorded audio, involves rethinking the place of digital technologies in the broader universe of twentieth-century communication history.

  15. Simulating Precambrian banded iron formation diagenesis

    Posth, Nicole R.; K??hler, Inga; D. Swanner, Elizabeth

    2013-01-01

    Post-depositional diagenetic alteration makes the accurate interpretation of key precipitation processes in ancient sediments, such as Precambrian banded iron formations (BIFs), difficult. While microorganisms are proposed as key contributors to BIF deposition, the diagenetic transformation...

  16. The NeXus data format.

    Könnecke, Mark; Akeroyd, Frederick A; Bernstein, Herbert J; Brewster, Aaron S; Campbell, Stuart I; Clausen, Björn; Cottrell, Stephen; Hoffmann, Jens Uwe; Jemian, Pete R; Männicke, David; Osborn, Raymond; Peterson, Peter F; Richter, Tobias; Suzuki, Jiro; Watts, Benjamin; Wintersberger, Eugen; Wuttke, Joachim

    2015-02-01

    NeXus is an effort by an international group of scientists to define a common data exchange and archival format for neutron, X-ray and muon experiments. NeXus is built on top of the scientific data format HDF5 and adds domain-specific rules for organizing data within HDF5 files, in addition to a dictionary of well defined domain-specific field names. The NeXus data format has two purposes. First, it defines a format that can serve as a container for all relevant data associated with a beamline. This is a very important use case. Second, it defines standards in the form of application definitions for the exchange of data between applications. NeXus provides structures for raw experimental data as well as for processed data.

  17. Quilting after mastectomy significantly reduces seroma formation

    reduce or prevent seroma formation among mastectomy patients ... of this prospective study is to evaluate the effect of surgical quilting ... Seroma was more common in smokers (p=0.003) and was not decreased by the .... explain its aetiology.

  18. The formation of planets by disc fragmentation

    Stamatellos Dimitris

    2013-04-01

    Full Text Available I discuss the role that disc fragmentation plays in the formation of gas giant and terrestrial planets, and how this relates to the formation of brown dwarfs and low-mass stars, and ultimately to the process of star formation. Protostellar discs may fragment, if they are massive enough and can cool fast enough, but most of the objects that form by fragmentation are brown dwarfs. It may be possible that planets also form, if the mass growth of a proto-fragment is stopped (e.g. if this fragment is ejected from the disc, or suppressed and even reversed (e.g by tidal stripping. I will discuss if it is possible to distinguish whether a planet has formed by disc fragmentation or core accretion, and mention of a few examples of observed exoplanets that are suggestive of formation by disc fragmentation.

  19. Stochastic Models of Molecule Formation on Dust

    Charnley, Steven; Wirstroem, Eva

    2011-01-01

    We will present new theoretical models for the formation of molecules on dust. The growth of ice mantles and their layered structure is accounted for and compared directly to observations through simulation of the expected ice absorption spectra

  20. Continuum Modeling of Biological Network Formation

    Albi, Giacomo; Burger, Martin; Haskovec, Jan; Markowich, Peter A.; Schlottbom, Matthias

    2017-01-01

    We present an overview of recent analytical and numerical results for the elliptic–parabolic system of partial differential equations proposed by Hu and Cai, which models the formation of biological transportation networks. The model describes

  1. Star formation: Sibling rivalry begins at birth

    Kratter, Kaitlin M.

    2015-02-01

    High-resolution astronomical observations of a nearby molecular gas cloud have revealed a quadruplet of stars in the act of formation. The system is arguably the youngest multiple star system detected so far. See Letter p.213

  2. KINETICS AND MECHANISM OF PRUSSIAN BLUE FORMATION ...

    Preferred Customer

    the 137Cs from radioactive waste solutions [7] and from humans and animals exposed to nuclear accidents [8]. PB and ... ferrocyanide ion resulting in formation of PB is used as a qualitative test for ferric ion. Although. Prussian ..... zeolites [21].

  3. 4 dnja v drugom formate / Dmitri Babitshenko

    Babitshenko, Dmitri

    2007-01-01

    25.-28. okt. Teises Teatris toimuvast festivalist "Teine formaat 2. Sügishooaeg" (Drugoi format 2), mille programmis on muusikat, teatrietendusi, luulet, tantsulavastusi ja filme. Festivali organiseerija on Teise Teatri administraator Anastassia Kulkova

  4. Transient Exciplex Formation Electron Transfer Mechanism

    Michael G. Kuzmin

    2011-01-01

    Full Text Available Transient exciplex formation mechanism of excited-state electron transfer reactions is analyzed in terms of experimental data on thermodynamics and kinetics of exciplex formation and decay. Experimental profiles of free energy, enthalpy, and entropy for transient exciplex formation and decay are considered for several electron transfer reactions in various solvents. Strong electronic coupling in contact pairs of reactants causes substantial decrease of activation energy relative to that for conventional long-range ET mechanism, especially for endergonic reactions, and provides the possibility for medium reorganization concatenated to gradual charge shift in contrast to conventional preliminary medium and reactants reorganization. Experimental criteria for transient exciplex formation (concatenated mechanism of excited-state electron transfer are considered. Available experimental data show that this mechanism dominates for endergonic ET reactions and provides a natural explanation for a lot of known paradoxes of ET reactions.

  5. Bonded exciplex formation: electronic and stereoelectronic effects.

    Wang, Yingsheng; Haze, Olesya; Dinnocenzo, Joseph P; Farid, Samir; Farid, Ramy S; Gould, Ian R

    2008-12-18

    As recently proposed, the singlet-excited states of several cyanoaromatics react with pyridine via bonded-exciplex formation, a novel concept in photochemical charge transfer reactions. Presented here are electronic and steric effects on the quenching rate constants, which provide valuable support for the model. Additionally, excited-state quenching in poly(vinylpyridine) is strongly inhibited both relative to that in neat pyridine and also to conventional exciplex formation in polymers, consistent with a restrictive orientational requirement for the formation of bonded exciplexes. Examples of competing reactions to form both conventional and bonded exciplexes are presented, which illustrate the delicate balance between these two processes when their reaction energetics are similar. Experimental and computational evidence is provided for the formation of a bonded exciplex in the reaction of the singlet excited state of 2,6,9,10-tetracyanoanthracene (TCA) with an oxygen-substituted donor, dioxane, thus expanding the scope of bonded exciplexes.

  6. The formation of citizens: the pediatrician's role

    Dioclécio Campos Júnior

    2016-05-01

    Conclusion: In the light of the disclosed scientific evidence, the pediatrician emerges as the most differentiated professional to provide preventive and curative care indispensable to the skilled formation of a healthy citizen.

  7. Resonance formation in photon-photon collisions

    Gidal, G.

    1988-08-01

    Recent experimental progress on resonance formation in photon-photon collisions is reviewed with particular emphasis on the pseudoscalar and tensor nonents and on the γγ* production of spin-one resonances. 37 refs., 17 figs., 5 tabs

  8. Inflow of atomic gas fuelling star formation

    Michałowski, M. J.; Gentile, G.; Hjorth, Jeppe

    2016-01-01

    Gamma-ray burst host galaxies are deficient in molecular gas, and show anomalous metal-poor regions close to GRB positions. Using recent Australia Telescope Compact Array (ATCA) Hi observations we show that they have substantial atomic gas reservoirs. This suggests that star formation in these ga......Gamma-ray burst host galaxies are deficient in molecular gas, and show anomalous metal-poor regions close to GRB positions. Using recent Australia Telescope Compact Array (ATCA) Hi observations we show that they have substantial atomic gas reservoirs. This suggests that star formation...... in these galaxies may be fuelled by recent inflow of metal-poor atomic gas. While this process is debated, it can happen in low-metallicity gas near the onset of star formation because gas cooling (necessary for star formation) is faster than the Hi-to-H2 conversion....

  9. Star Formation in low mass galaxies

    Mehta, Vihang

    2018-01-01

    Our current hierarchical view of the universe asserts that the large galaxies we see today grew via mergers of numerous smaller galaxies. As evidenced by recent literature, the collective impact of these low mass galaxies on the universe is more substantial than previously thought. Studying the growth and evolution of these low mass galaxies is critical to our understanding of the universe as a whole. Star formation is one of the most important ongoing processes in galaxies. Forming stars is fundamental to the growth of a galaxy. One of the main goals of my thesis is to analyze the star formation in these low mass galaxies at different redshifts.Using the Hubble UltraViolet Ultra Deep Field (UVUDF), I investigate the star formation in galaxies at the peak of the cosmic star formation history using the ultraviolet (UV) light as a star formation indicator. Particularly, I measure the UV luminosity function (LF) to probe the volume-averaged star formation properties of galaxies at these redshifts. The depth of the UVUDF is ideal for a direct measurement of the faint end slope of the UV LF. This redshift range also provides a unique opportunity to directly compare UV to the "gold standard" of star formation indicators, namely the Hα nebular emission line. A joint analysis of the UV and Hα LFs suggests that, on average, the star formation histories in low mass galaxies (~109 M⊙) are more bursty compared to their higher mass counterparts at these redshifts.Complementary to the analysis of the average star formation properties of the bulk galaxy population, I investigate the details of star formation in some very bursty galaxies at lower redshifts selected from Spitzer Large Area Survey with Hyper-Suprime Cam (SPLASH). Using a broadband color-excess selection technique, I identify a sample of low redshift galaxies with bright nebular emission lines in the Subaru-XMM Deep Field (SXDF) from the SPLASH-SXDF catalog. These galaxies are highly star forming and have

  10. Charmonium formation and suppression in nuclear matter

    Xu Jiajun; Wang Jia; Zhuang Chao; Zhuang Pengfei

    2005-01-01

    The coupling Schroedinger equations describing the evolution of cc-bar states in nuclear matter are analytically and systematically solved via perturbation method, and the correlation between charmonium formation and nuclear absorption is investigated. After calculating J/Ψ and Ψ' suppression in nucleon-nucleus collisions and comparing with experiment data, it is found that the formation time effect plays an important rule in charmonium suppression, especially in Ψ' suppression. (authors)

  11. THE STAGES OF ACCOUNTING POLICIES FORMATION

    Kafka, Sofiia

    2017-01-01

    In the article the research of the existing scientists’ approaches to the procedure of the company accounting policy formation have been done, their critical analysis has been made, the major groups of issues and problems raised in scientific works have been found out, and those ones, which require the further up-to- date refinement, have been identified: the formation of the stages in projecting of the accounting policy in accordance with requirements of legislation. For the purposes of stud...

  12. Formation of soap bubbles by gas jet

    Zhou, M. L.; Li, M.; Chen, Z. Y.; Han, J. F.; Liu, D.

    2017-01-01

    Soap bubbles can be easily generated by varies methods, while their formation process is complicated and still worth study. A model about the bubble formation process was proposed in Phys. Rev. Lett. 116, 077801 recently, and it was reported that the bubbles were formed when the gas blowing velocity was above one threshold. However, after repeating these experiments, we found the bubbles could be generated in two velocities ranges which corresponded to laminar and turbulent gas jet respective...

  13. Insights from simulations of star formation

    Larson, Richard B

    2007-01-01

    Although the basic physics of star formation is classical, numerical simulations have yielded essential insights into how stars form. They show that star formation is a highly nonuniform runaway process characterized by the emergence of nearly singular peaks in density, followed by the accretional growth of embryo stars that form at these density peaks. Circumstellar discs often form from the gas being accreted by the forming stars, and accretion from these discs may be episodic, driven by gravitational instabilities or by protostellar interactions. Star-forming clouds typically develop filamentary structures, which may, along with the thermal physics, play an important role in the origin of stellar masses because of the sensitivity of filament fragmentation to temperature variations. Simulations of the formation of star clusters show that the most massive stars form by continuing accretion in the dense cluster cores, and this again is a runaway process that couples star formation and cluster formation. Star-forming clouds also tend to develop hierarchical structures, and smaller groups of forming objects tend to merge into progressively larger ones, a generic feature of self-gravitating systems that is common to star formation and galaxy formation. Because of the large range of scales and the complex dynamics involved, analytic models cannot adequately describe many aspects of star formation, and detailed numerical simulations are needed to advance our understanding of the subject. 'The purpose of computing is insight, not numbers.' Richard W Hamming, in Numerical Methods for Scientists and Engineers (1962) 'There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.' William Shakespeare, in Hamlet, Prince of Denmark (1604) (key issues review)

  14. Insights from simulations of star formation

    Larson, Richard B [Department of Astronomy, Yale University, Box 208101, New Haven, CT 06520-8101 (United States)

    2007-03-15

    Although the basic physics of star formation is classical, numerical simulations have yielded essential insights into how stars form. They show that star formation is a highly nonuniform runaway process characterized by the emergence of nearly singular peaks in density, followed by the accretional growth of embryo stars that form at these density peaks. Circumstellar discs often form from the gas being accreted by the forming stars, and accretion from these discs may be episodic, driven by gravitational instabilities or by protostellar interactions. Star-forming clouds typically develop filamentary structures, which may, along with the thermal physics, play an important role in the origin of stellar masses because of the sensitivity of filament fragmentation to temperature variations. Simulations of the formation of star clusters show that the most massive stars form by continuing accretion in the dense cluster cores, and this again is a runaway process that couples star formation and cluster formation. Star-forming clouds also tend to develop hierarchical structures, and smaller groups of forming objects tend to merge into progressively larger ones, a generic feature of self-gravitating systems that is common to star formation and galaxy formation. Because of the large range of scales and the complex dynamics involved, analytic models cannot adequately describe many aspects of star formation, and detailed numerical simulations are needed to advance our understanding of the subject. 'The purpose of computing is insight, not numbers.' Richard W Hamming, in Numerical Methods for Scientists and Engineers (1962) 'There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.' William Shakespeare, in Hamlet, Prince of Denmark (1604) (key issues review)

  15. Search of massive star formation with COMICS

    Okamoto, Yoshiko K.

    2004-04-01

    Mid-infrared observations is useful for studies of massive star formation. Especially COMICS offers powerful tools: imaging survey of the circumstellar structures of forming massive stars such as massive disks and cavity structures, mass estimate from spectroscopy of fine structure lines, and high dispersion spectroscopy to census gas motion around formed stars. COMICS will open the next generation infrared studies of massive star formation.

  16. Star Formation Histories of Nearby Dwarf Galaxies

    Grebel, Eva K.

    2000-01-01

    Properties of nearby dwarf galaxies are briefly discussed. Dwarf galaxies vary widely in their star formation histories, the ages of their subpopulations, and in their enrichment history. Furthermore, many dwarf galaxies show evidence for spatial variations in their star formation history; often in the form of very extended old populations and radial gradients in age and metallicity. Determining factors in dwarf galaxy evolution appear to be both galaxy mass and environment. We may be observi...

  17. Radiation pressure in super star cluster formation

    Tsang, Benny T.-H.; Milosavljević, Miloš

    2018-05-01

    The physics of star formation at its extreme, in the nuclei of the densest and the most massive star clusters in the universe—potential massive black hole nurseries—has for decades eluded scrutiny. Spectroscopy of these systems has been scarce, whereas theoretical arguments suggest that radiation pressure on dust grains somehow inhibits star formation. Here, we harness an accelerated Monte Carlo radiation transport scheme to report a radiation hydrodynamical simulation of super star cluster formation in turbulent clouds. We find that radiation pressure reduces the global star formation efficiency by 30-35%, and the star formation rate by 15-50%, both relative to a radiation-free control run. Overall, radiation pressure does not terminate the gas supply for star formation and the final stellar mass of the most massive cluster is ˜1.3 × 106 M⊙. The limited impact as compared to in idealized theoretical models is attributed to a radiation-matter anti-correlation in the supersonically turbulent, gravitationally collapsing medium. In isolated regions outside massive clusters, where the gas distribution is less disturbed, radiation pressure is more effective in limiting star formation. The resulting stellar density at the cluster core is ≥108 M⊙ pc-3, with stellar velocity dispersion ≳ 70 km s-1. We conclude that the super star cluster nucleus is propitious to the formation of very massive stars via dynamical core collapse and stellar merging. We speculate that the very massive star may avoid the claimed catastrophic mass loss by continuing to accrete dense gas condensing from a gravitationally-confined ionized phase.

  18. The effect of anisotropy on galaxy formation

    Burkert, A.; Hensler, G.

    1987-01-01

    Two-dimensional calculations of galaxy formation are presented. Gas and stars are taken into account as two distinct components interacting by star formation and stellar mass loss. While the gas is described by means of the Eulerian equation, the authors allow for an anisotropic velocity distribution among the stars by applying the collisionless Boltzmann equation. In the first model, the authors succeed in developing totally different stellar populations forming a halo and a disc. (author)

  19. Star formation histories of irregular galaxies

    Gallagher, J.S. III; Hunter, D.A.; Tutukov, A.V.

    1984-01-01

    We explore the star formation histories of a selection of irregular and spiral galaxies by using three parameters that sample the star formation rate (SFR) at different epochs: (1) the mass of a galaxy in the form of stars measures the SFR integrated over a galaxy's lifetime; (2) the blue luminosity is dominated primarily by stars formed over the past few billion years; and (3) Lyman continuum photon fluxes derived from Hα luminosities give the current ( 8 yr) SFR

  20. A theory of biological pattern formation

    Gierer, Alfred; Meinhardt, H.

    2006-01-01

    The paper addresses the formation of striking patterns within originally near-homogenous tissue, the process prototypical for embryology, and represented in particularly puristic form by cut sections of hydra regenerating a complete animal with head and foot. Essential requirements are autocatalytic, self-enhancing activation, combined with inhibitory or depletion effects of wider range - “lateral inhibition”. Not only de-novo-pattern formation, but also well known, striking features of devel...

  1. The significance of Gosau-type basins for the Late Cretaceous tectonic history of the Alpine-Carpathian Belt.

    Willingshofer, E.; Neubauer, F.; Cloetingh, S.A.P.L.

    1999-01-01

    A key feature of Late Creataceous tectonics throughout the Alpine-Carpathian-Pannonian (ALCAPA) region is the synchronous formation of sedimentary basins (Gosau basins) and exhumation of metamorphic domes. Initial subsidence, spatially varying in time (Cenomanian-Santonian), within Gosau-type basins

  2. Output formatting in Apple-Soft Basic

    Navale, A.S.

    1987-01-01

    Personal computers are being used extensively in various fields. BASIC is a very popular and widely used language in personal computers. Apple computer is one of the popular machines used for scientific and engineering applications. Presenting output from computers in a neat and easy to read form is very important. Languages like FORTRAN have utility command 'FORMAT' which takes care of the formatting of the output in user-defined form. In some versions of BASIC a PRINT USING facility is available but it is not as powerful as the FORTRAN statement 'FORMAT'. Applesoft basic does not have even this PRINT USING command. Programmers have to write their own program segments to handle output formatting in Applesoft BASIC. Generally, such user written programs are of limited use as they cannot be used easily with other programs. A general purpose and easily transportable subroutine in Applesoft BASIC is presented here for handling output formatting in user-defined structure. The subroutine is nearly as powerful as the FORMAT statement in FORTRAN. It can also be used in other versions of BASIC with very little modifications. 3 tables, 4 refs. (author)

  3. Adolescent Violent Victimization and Precocious Union Formation.

    C Kuhl, Danielle; Warner, David F; Wilczak, Andrew

    2012-11-01

    This article bridges scholarship in criminology and family sociology by extending arguments about "precocious exits" from adolescence to consider early union formation as a salient outcome of violent victimization for youths. Research indicates that early union formation is associated with several negative outcomes; yet the absence of attention to union formation as a consequence of violent victimization is noteworthy. We address this gap by drawing on life course theory and data from the National Longitudinal Study of Adolescent Health (Add Health) to examine the effect of violent victimization ("street" violence) on the timing of first co-residential union formation-differentiating between marriage and cohabitation-in young adulthood. Estimates from Cox proportional hazard models show that adolescent victims of street violence experience higher rates of first union formation, especially marriage, early in the transition to adulthood; however, this effect declines with age, as such unions become more normative. Importantly, the effect of violent victimization on first union timing is robust to controls for nonviolent delinquency, substance abuse, and violent perpetration. We conclude by discussing directions for future research on the association between violent victimization and coresidential unions with an eye toward the implications of such early union formation for desistance.

  4. Recognizing team formation in american football

    Atmosukarto, Indriyati

    2014-01-01

    Most existing software packages for sports video analysis require manual annotation of important events in the video. Despite being the most popular sport in the United States, most American football game analysis is still done manually. Line of scrimmage and offensive team formation recognition are two statistics that must be tagged by American Football coaches when watching and evaluating past play video clips, a process which takesmanyman hours per week. These two statistics are the building blocks for more high-level analysis such as play strategy inference and automatic statistic generation. In this chapter, we propose a novel framework where given an American football play clip, we automatically identify the video frame in which the offensive team lines in formation (formation frame), the line of scrimmage for that play, and the type of player formation the offensive team takes on. The proposed framework achieves 95% accuracy in detecting the formation frame, 98% accuracy in detecting the line of scrimmage, and up to 67%accuracy in classifying the offensive team’s formation. To validate our framework, we compiled a large dataset comprising more than 800 play-clips of standard and high definition resolution from real-world football games. This dataset will be made publicly available for future comparison.

  5. Star formation in active galaxies and quasars

    Heckman, T.M.

    1987-01-01

    I review the observational evidence for a causal or statistical link between star formation and active galactic nuclei. The chief difficulty is in quantitatively ascertaining the star formation rate in active galaxies: most of the readily observable manifestations of star formation superficially resemble those of an active nucleus. Careful multi-wavelength spatially-resolved observations demonstrate that many Seyfert galaxies are undergoing star formation. Our survey of CO emission from Seyferts (interpreted in conjunction IRAS data) suggests that type 2 Seyferts have unusually high rates of star formation, but type 1 Seyferts do not. Recent work also suggests that many powerful radio galaxies may be actively forming stars: radio galaxies with strong emission-lines often have blue colors and strong far-infrared emission. Determining the star formation rate in the host galaxies of quasars is especially difficult. Multi-color imaging and long-slit spectroscopy suggests that many of the host galaxies of radio-loud quasars are blue and a cold interstellar medium has been detected in some quasar hosts

  6. Converting Taxonomic Descriptions to New Digital Formats

    Hong Cui

    2008-01-01

    Full Text Available Abstract.--The majority of taxonomic descriptions is currently in print format. The majority of digital descriptions are in formats such as DOC, HTML, or PDF and for human readers. These formats do not convey rich semantics in taxonomic descriptions for computer-aided process. Newer digital formats such as XML and RDF accommodate semantic annotations that allow computers to process the rich semantics on human's behalf, thus open up opportunities for a wide range of innovative usages of taxonomic descriptions, such as searching in more precise and flexible ways, integrating with gnomic and geographic information, generating taxonomic keys automatically, and text data mining and information visualization etc. This paper discusses the challenges in automated conversion of multiple collections of descriptions to XML format and reports an automated system, MARTT. MARTT is a machine-learning system that makes use of training examples to tag new descriptions into XML format. A number of utilities are implemented as solutions to the challenges. The utilities are used to reduce the effort for training example preparation, to facilitate the creation of a comprehensive schema, and to predict system performance on a new collection of descriptions. The system has been tested with several plant and alga taxonomic publications including Flora of China and Flora of North America.

  7. The three phases of galaxy formation

    Clauwens, Bart; Schaye, Joop; Franx, Marijn; Bower, Richard G.

    2018-05-01

    We investigate the origin of the Hubble sequence by analysing the evolution of the kinematic morphologies of central galaxies in the EAGLE cosmological simulation. By separating each galaxy into disc and spheroidal stellar components and tracing their evolution along the merger tree, we find that the morphology of galaxies follows a common evolutionary trend. We distinguish three phases of galaxy formation. These phases are determined primarily by mass, rather than redshift. For M* ≲ 109.5M⊙ galaxies grow in a disorganised way, resulting in a morphology that is dominated by random stellar motions. This phase is dominated by in-situ star formation, partly triggered by mergers. In the mass range 109.5M⊙ ≲ M* ≲ 1010.5M⊙ galaxies evolve towards a disc-dominated morphology, driven by in-situ star formation. The central spheroid (i.e. the bulge) at z = 0 consists mostly of stars that formed in-situ, yet the formation of the bulge is to a large degree associated with mergers. Finally, at M* ≳ 1010.5M⊙ growth through in-situ star formation slows down considerably and galaxies transform towards a more spheroidal morphology. This transformation is driven more by the buildup of spheroids than by the destruction of discs. Spheroid formation in these galaxies happens mostly by accretion at large radii of stars formed ex-situ (i.e. the halo rather than the bulge).

  8. Networks for Autonomous Formation Flying Satellite Systems

    Knoblock, Eric J.; Konangi, Vijay K.; Wallett, Thomas M.; Bhasin, Kul B.

    2001-01-01

    The performance of three communications networks to support autonomous multi-spacecraft formation flying systems is presented. All systems are comprised of a ten-satellite formation arranged in a star topology, with one of the satellites designated as the central or "mother ship." All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/lP over ATM protocol architecture within the formation the second system uses the IEEE 802.11 protocol architecture within the formation and the last system uses both of the previous architectures with a constellation of geosynchronous satellites serving as an intermediate point-of-contact between the formation and the terrestrial network. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IF queuing delay, and IP processing delay at the mother ship as well as application-level round-trip time for both systems, In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

  9. HOW GALACTIC ENVIRONMENT REGULATES STAR FORMATION

    Meidt, Sharon E. [Max-Planck-Institut für Astronomie/Königstuhl 17 D-69117 Heidelberg (Germany)

    2016-02-10

    In a new simple model I reconcile two contradictory views on the factors that determine the rate at which molecular clouds form stars—internal structure versus external, environmental influences—providing a unified picture for the regulation of star formation in galaxies. In the presence of external pressure, the pressure gradient set up within a self-gravitating turbulent (isothermal) cloud leads to a non-uniform density distribution. Thus the local environment of a cloud influences its internal structure. In the simple equilibrium model, the fraction of gas at high density in the cloud interior is determined simply by the cloud surface density, which is itself inherited from the pressure in the immediate surroundings. This idea is tested using measurements of the properties of local clouds, which are found to show remarkable agreement with the simple equilibrium model. The model also naturally predicts the star formation relation observed on cloud scales and at the same time provides a mapping between this relation and the closer-to-linear molecular star formation relation measured on larger scales in galaxies. The key is that pressure regulates not only the molecular content of the ISM but also the cloud surface density. I provide a straightforward prescription for the pressure regulation of star formation that can be directly implemented in numerical models. Predictions for the dense gas fraction and star formation efficiency measured on large-scales within galaxies are also presented, establishing the basis for a new picture of star formation regulated by galactic environment.

  10. Seroma formation after surgery for breast cancer

    Ebrahimi Mandana

    2004-12-01

    Full Text Available Abstract Background Seroma formation is the most frequent postoperative complication after breast cancer surgery. We carried out a study to investigate the effect of various demographic, clinical and therapeutic variables on seroma formation. Patients and methods A retrospective cross sectional study of patients who underwent surgical therapy for breast cancer with either modified radical mastectomy (MRM or breast preservation (BP was carried out. The demographic data and clinical information were extracted from case records. Seroma formation was studied in relation to age, type of surgery, tumor size, nodal involvement, preoperative chemotherapy, surgical instrument (electrocautery or scalpel, use of pressure garment, and duration of drainage. The multiple logistic regression analysis was performed to estimate odds ratios. Results A total of 158 patients with breast cancer were studied. The mean age of the patients was 46.3 years (SD ± 11.9. Seventy-three percent underwent modified radical mastectomy and the remaining 27% received breast preservation surgery. Seroma occurred in 35% of patients. In multivariate logistic regression analysis an association of postoperative seroma formation was noted with modified radical mastectomy (OR = 2.83, 95% CI 1.01–7.90, P = 0.04. No other factor studied was found to significantly effect the seroma formation after breast cancer surgery. Conclusion The findings suggest that the type of surgery is a predicting factor for seroma formation in breast cancer patients.

  11. Digital Forensics Formats: Seeking a Digital Preservation Storage Container Format for Web Archiving

    Yunhyong Kim

    2012-12-01

    Full Text Available In this paper we discuss archival storage container formats from the point of view of digital curation and preservation, an aspect of preservation overlooked by most other studies. Considering established approaches to data management as our jumping off point, we selected seven container format attributes that are core to the long term accessibility of digital materials. We have labeled these core preservation attributes. These attributes are then used as evaluation criteria to compare storage container formats belonging to five common categories: formats for archiving selected content (e.g. tar, WARC, disk image formats that capture data for recovery or installation (partimage, dd raw image, these two types combined with a selected compression algorithm (e.g. tar+gzip, formats that combine packing and compression (e.g. 7-zip, and forensic file formats for data analysis in criminal investigations (e.g. aff – Advanced Forensic File format. We present a general discussion of the storage container format landscape in terms of the attributes we discuss, and make a direct comparison between the three most promising archival formats: tar, WARC, and aff. We conclude by suggesting the next steps to take the research forward and to validate the observations we have made.

  12. Thermodynamics and kinetics of vesicles formation processes.

    Guida, Vincenzo

    2010-12-15

    Vesicles are hollow aggregates, composed of bilayers of amphiphilic molecules, dispersed into and filled with a liquid solvent. These aggregates can be formed either as equilibrium or as out of equilibrium meta-stable structures and they exhibit a rich variety of different morphologies. The surprising richness of structures, the vast range of industrial applications and the presence of vesicles in a number of biological systems have attracted the interest of numerous researchers and scientists. In this article, we review both the thermodynamics and the kinetics aspects of the phenomena of formation of vesicles. We start presenting the thermodynamics of bilayer membranes formation and deformation, with the aim of deriving the conditions for the existence of equilibrium vesicles. Specifically, we use the results from continuum thermodynamics to discuss the possibility of formation of stable equilibrium vesicles, from both mixed amphiphiles and single component systems. We also link the bilayer membrane properties to the molecular structure of the starting amphiphiles. In the second part of this article, we focus on the dynamics and kinetics of vesiculation. We review the process of vesicles formation both from planar lamellar phase under shear and from isotropic micelles. In order to clarify the physical mechanisms of vesicles formation, we continuously draw a parallel between emulsification and vesiculation processes. Specifically, we compare the experimental results, the driving forces and the relative scaling laws identified for the two processes. Describing the dynamics of vesicles formation, we also discuss why non equilibrium vesicles can be formed by kinetics control and why they are meta-stable. Understanding how to control the properties, the stability and the formation process of vesicles is of fundamental importance for a vast number of industrial applications. Copyright © 2009. Published by Elsevier B.V.

  13. Free-format RPG IV the express guide to learning free format

    Martin, Jim

    2015-01-01

    Focusing strictly on teaching free-format RPG programming methods, this book will help programmers wishing to upgrade their skills   This how-to guide offers a concise and thorough introduction to the increased productivity, better readability, and easier program maintenance that comes with the free-format style of programming in RPG IV. Although free-format information is available in IBM manuals, it is not separated from everything else, requiring hours of tedious research to track down the information needed. This book provides everything you need to know to write RPG IV in the free-format

  14. Adolescent Violent Victimization and Precocious Union Formation*

    C. Kuhl, Danielle; Warner, David F.; Wilczak, Andrew

    2013-01-01

    This article bridges scholarship in criminology and family sociology by extending arguments about “precocious exits” from adolescence to consider early union formation as a salient outcome of violent victimization for youths. Research indicates that early union formation is associated with several negative outcomes; yet the absence of attention to union formation as a consequence of violent victimization is noteworthy. We address this gap by drawing on life course theory and data from the National Longitudinal Study of Adolescent Health (Add Health) to examine the effect of violent victimization (“street” violence) on the timing of first co-residential union formation—differentiating between marriage and cohabitation—in young adulthood. Estimates from Cox proportional hazard models show that adolescent victims of street violence experience higher rates of first union formation, especially marriage, early in the transition to adulthood; however, this effect declines with age, as such unions become more normative. Importantly, the effect of violent victimization on first union timing is robust to controls for nonviolent delinquency, substance abuse, and violent perpetration. We conclude by discussing directions for future research on the association between violent victimization and coresidential unions with an eye toward the implications of such early union formation for desistance. PMID:24431471

  15. The formation of stellar black holes

    Mirabel, Félix

    2017-08-01

    It is believed that stellar black holes (BHs) can be formed in two different ways: Either a massive star collapses directly into a BH without a supernova (SN) explosion, or an explosion occurs in a proto-neutron star, but the energy is too low to completely unbind the stellar envelope, and a large fraction of it falls back onto the short-lived neutron star (NS), leading to the delayed formation of a BH. Theoretical models set progenitor masses for BH formation by implosion, namely, by complete or almost complete collapse, but observational evidences have been elusive. Here are reviewed the observational insights on BHs formed by implosion without large natal kicks from: (1) the kinematics in three dimensions of space of five Galactic BH X-ray binaries (BH-XRBs), (2) the diversity of optical and infrared observations of massive stars that collapse in the dark, with no luminous SN explosions, possibly leading to the formation of BHs, and (3) the sources of gravitational waves (GWs) produced by mergers of stellar BHs so far detected with LIGO. Multiple indications of BH formation without ejection of a significant amount of matter and with no natal kicks obtained from these different areas of observational astrophysics, and the recent observational confirmation of the expected dependence of BH formation on metallicity and redshift, are qualitatively consistent with the high merger rates of binary black holes (BBHs) inferred from the first detections with LIGO.

  16. Star Cluster Structure from Hierarchical Star Formation

    Grudic, Michael; Hopkins, Philip; Murray, Norman; Lamberts, Astrid; Guszejnov, David; Schmitz, Denise; Boylan-Kolchin, Michael

    2018-01-01

    Young massive star clusters (YMCs) spanning 104-108 M⊙ in mass generally have similar radial surface density profiles, with an outer power-law index typically between -2 and -3. This similarity suggests that they are shaped by scale-free physics at formation. Recent multi-physics MHD simulations of YMC formation have also produced populations of YMCs with this type of surface density profile, allowing us to narrow down the physics necessary to form a YMC with properties as observed. We show that the shallow density profiles of YMCs are a natural result of phase-space mixing that occurs as they assemble from the clumpy, hierarchically-clustered configuration imprinted by the star formation process. We develop physical intuition for this process via analytic arguments and collisionless N-body experiments, elucidating the connection between star formation physics and star cluster structure. This has implications for the early-time structure and evolution of proto-globular clusters, and prospects for simulating their formation in the FIRE cosmological zoom-in simulations.

  17. Performance of Different Acids on Sandstone Formations

    M. A. Zaman

    2013-12-01

    Full Text Available Stimulation of sandstone formations is a challenging task, which involves several chemicals and physical interactions of the acid with the formation. Some of these reactions may result in formation damage. Mud acid has been successfully used to stimulate sandstone reservoirs for a number of years. It is a mixture of hydrofluoric (HF and hydrochloric (HCl acids designed to dissolve clays and siliceous fines accumulated in the near-wellbore region. Matrix acidizing may also be used to increase formation permeability in undamaged wells. The change may be up to 50% to 100% with the mud acid. For any acidizing process, the selection of acid (Formulation and Concentration and the design (Pre-flush, Main Acid, After-flush is very important. Different researchers are using different combinations of acids with different concentrations to get the best results for acidization. Mainly the common practice is combination of Hydrochloric Acid – Hydrofluoric with Concentration (3% HF – 12% HCl. This paper presents the results of a laboratory investigation of Orthophosphoric acid instead of hydrochloric acid in one combination and the second combination is Fluoboric and formic acid and the third one is formic and hydrofluoric acid. The results are compared with the mud acid and the results calculated are porosity, permeability, and FESEM Analysis and Strength tests. All of these new combinations shows that these have the potential to be used as acidizing acids on sandstone formations.

  18. PRINCIPLES OF CONTENT FORMATION EDUCATIONAL ELECTRONIC RESOURCE

    О Ю Заславская

    2017-12-01

    Full Text Available The article considers modern possibilities of information and communication technologies for the design of electronic educational resources. The conceptual basis of the open educational multimedia system is based on the modular architecture of the electronic educational resource. The content of the electronic training module can be implemented in several versions of the modules: obtaining information, practical exercises, control. The regularities in the teaching process in modern pedagogical theory are considered: general and specific, and the principles for the formation of the content of instruction at different levels are defined, based on the formulated regularities. On the basis of the analysis, the principles of the formation of the electronic educational resource are determined, taking into account the general and didactic patterns of teaching.As principles of the formation of educational material for obtaining information for the electronic educational resource, the article considers: the principle of methodological orientation, the principle of general scientific orientation, the principle of systemic nature, the principle of fundamentalization, the principle of accounting intersubject communications, the principle of minimization. The principles of the formation of the electronic training module of practical studies in the article include: the principle of systematic and dose based consistency, the principle of rational use of study time, the principle of accessibility. The principles of the formation of the module for monitoring the electronic educational resource can be: the principle of the operationalization of goals, the principle of unified identification diagnosis.

  19. Mousse photochemistry formation; Formacao fotoquimica de mousse

    Rangel, George W.M.; Nicodem, David E. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Quimica]. E-mail: gwallace_iq@yahoo.com.br; nicodem@iq.ufrj.br

    2003-07-01

    The petroleum, when spilled in the sea it forms an emulsion of water in oil could contain up to 90% of water. This emulsion, called Mousse of Chocolate, it can be very stable, taking to the increase of the environmental impact and impeding the microbiological degradation. It was observed that the petroleum, when irradiated with solar light, it forms Mousse more easily. However, same being known about the importance of the action of the light in the formation of Mousse, little it is known regarding the processes and conditions involved in the formation of Mousse. This project proposes the study of the process of formation of Mousse, in function of the suffered transformations for petroleum after solar irradiation. We will study the relationship between the stability and formation of Mousse and the present amount of asphaltenes in the petroleum as a result of the irradiation. We will develop a methodology for analysis of emulsions of water in petroleum, in way we know her/it the stability of the emulsion in function of the time and the amount of water in the same. We will study the behavior of a sample of Brazilian petroleum of Campos' Basin, already used in other photochemistry studies. We will analyze the effect of the time of irradiation in the asphaltenes formation and Mousse. We will also analyze other types of petroleum, for us to compare results with obtained them in the Brazilian petroleum. (author)

  20. Laser filament-induced aerosol formation

    H. Saathoff

    2013-05-01

    Full Text Available Using the aerosol and cloud simulation chamber AIDA, we investigated the laser filament induced particle formation in ambient air, humid synthetic air, humid nitrogen, argon–oxygen mixture, and pure argon in order to simulate the particle formation under realistic atmospheric conditions as well as to investigate the influence of typical gas-phase atmospheric constituents on the particle formation. Terawatt laser plasma filaments generated new particles in the size range 3 to 130 nm with particle production rates ranging from 1 × 107 to 5 × 109 cm−3 plasma s−1 for the given experimental conditions. In all cases the particle formation rates increased exponentially with the water content of the gas mixture. Furthermore, the presence of a few ppb of trace gases like SO2 and α-pinene clearly enhanced the particle yield by number, the latter also by mass. Our findings suggest that new particle formation is efficiently supported by oxidized species like acids generated by the photoionization of both major and minor components of the air, including N2, NH3, SO2 and organics.

  1. Dust formation and ionization in novae

    Yamamoto, Tetsuo; Sato, Shuji; Nariai, Kyoji.

    1979-01-01

    In order to explain the fact that some novae show the increase of infrared radiation indicating the formation of circumstellar dust grains while some others do not, the theory that the formation of dust in the circumstellar envelope of a nova depends on the intensity of ultraviolet radiation from a central star has been presented. It is known that the central star of a nova emits radiation at nearly constant rate, and its effective temperature rises. It was concluded that the novae with higher emission than a certain value are the poor candidates for dust formation because the whole envelope is ionized before dust is formed. But this conclusion is misleading. The evolution of the ultraviolet radiation emanating from a central star is summarized. The condensation of grains is possible when the partial pressure of the vapor, from which the grains are formed, becomes higher than the saturation vapor pressure. The temperature of grains can be estimated by equating the radiations absorbed and emitted. The grains evaporate if the grain temperature is higher than the condensation temperature. The formation of a Stroemgren sphere in the exploding envelope of a nova is discussed. For the formation of grains, it is necessary that temperature drops below the condensation temperature before the whole envelope is ionized. Hence dust grains do not grow if the grain temperature at a phase is higher than the condensation temperature. (Kako, I.)

  2. Formation and fragmentation of protostellar dense cores

    Maury, Anaelle

    2009-01-01

    Stars form in molecular clouds, when they collapse and fragment to produce protostellar dense cores. These dense cores are then likely to contract under their own gravity, and form young protostars, that further evolve while accreting their circumstellar mass, until they reach the main sequence. The main goal of this thesis was to study the formation and fragmentation of protostellar dense cores. To do so, two main studies, described in this manuscript, were carried out. First, we studied the formation of protostellar cores by quantifying the impact of protostellar outflows on clustered star formation. We carried out a study of the protostellar outflows powered by the young stellar objects currently formed in the NGc 2264-C proto-cluster, and we show that protostellar outflows seem to play a crucial role as turbulence progenitors in clustered star forming regions, although they seem unlikely to significantly modify the global infall processes at work on clump scales. Second, we investigated the formation of multiple systems by core fragmentation, by using high - resolution observations that allow to probe the multiplicity of young protostars on small scales. Our results suggest that the multiplicity rate of protostars on small scales increase while they evolve, and thus favor dynamical scenarios for the formation of multiple systems. Moreover, our results favor magnetized scenarios of core collapse to explain the small-scale properties of protostars at the earliest stages. (author) [fr

  3. Star formations rates in the Galaxy

    Smith, L.F.; Mezger, P.G.; Biermann, P.

    1978-01-01

    Data relevant to giant HII regions in the Galaxy are collected. The production rate for Lyman continuum photons by O stars in giant HII regions is 4.7 10 52 s -1 in the whole Galaxy. The corresponding present rate of star formation is M (sun)/yr, of which 74% occurs in main spiral arms, 13% in the interarm region and 13% in the galactic center. The star formation rates, the observed heavy element and deuterium abundances in the solar neighbourhood are compared to model predictions based on star formation proportional to a power (k) of the gas surface density. The mass function is terminated at Msub(u)=100 M (sun) above and M 1 below. Msub(u)=50 M (sun) is also considered. Comparing with data derived from observations a) the star formation rate, b) metal abundances, c) deuterium abundances, and d) colors of the stellar population, we find that models of k=1/2 to 1, and M 1 1 M (sun) are formed together with O and B stars, but under rather special conditions of the interstellar gas, while lower mass stars form wherever dense molecular clouds exist. The high rate of star formation in the galactic center may represent a burst. (orig.) [de

  4. Star formation in evolving molecular clouds

    Völschow, M.; Banerjee, R.; Körtgen, B.

    2017-09-01

    Molecular clouds are the principle stellar nurseries of our universe; they thus remain a focus of both observational and theoretical studies. From observations, some of the key properties of molecular clouds are well known but many questions regarding their evolution and star formation activity remain open. While numerical simulations feature a large number and complexity of involved physical processes, this plethora of effects may hide the fundamentals that determine the evolution of molecular clouds and enable the formation of stars. Purely analytical models, on the other hand, tend to suffer from rough approximations or a lack of completeness, limiting their predictive power. In this paper, we present a model that incorporates central concepts of astrophysics as well as reliable results from recent simulations of molecular clouds and their evolutionary paths. Based on that, we construct a self-consistent semi-analytical framework that describes the formation, evolution, and star formation activity of molecular clouds, including a number of feedback effects to account for the complex processes inside those objects. The final equation system is solved numerically but at much lower computational expense than, for example, hydrodynamical descriptions of comparable systems. The model presented in this paper agrees well with a broad range of observational results, showing that molecular cloud evolution can be understood as an interplay between accretion, global collapse, star formation, and stellar feedback.

  5. Microwave based method of monitoring crack formation

    Aman, Sergej; Aman, Alexander; Majcherek, Soeren; Hirsch, Soeren; Schmidt, Bertram

    2014-01-01

    The formation of cracks in glass particles was monitored by application of linearly polarized microwaves. The breakage behavior of glass spheres coated with a thin gold layer of about 50 nm, i.e. a thickness that is lower than the microwave penetration depth, was tested. In this way the investigation of fracture behavior of electronic circuits was simulated. A shielding current was induced in the gold layer by the application of microwaves. During the crack formation the distribution of this current changed abruptly and a scattered microwave signal appeared at the frequency of the incident microwaves. The time behavior of the scattered signal reflects the microscopic processes occurring during the fracture of the specimen. The duration of the increasing signal corresponds to the crack formation time in the tested specimen. This time was estimated as particle size divided by crack development speed in glass. An intense emission of electrons occurs during the formation of cracks. Due to this, coherent Thomson scattering of microwaves by emitted electrons becomes significant with a delay of a few microseconds after the initial phase of crack formation. In this time the intensity of the microwave signal increases. (paper)

  6. Interstellar clouds and the formation of stars

    Alfven, H; Carlqvist, P [Kungliga Tekniska Hoegskolan, Stockholm (Sweden). Institutionen foer Plasmafysik

    1978-05-01

    Part I gives a survey of the drastic revision of cosmic plasma physics which is precipitated by the exploration of the magnetosphere through in situ measurements. The 'pseudo-plasma formalism', which until now has almost completely dominated theoretical astrophysics, must be replaced by an experimentally based approach involving the introduction of a number of neglected plasma phenomena, such as electric double layers, critical velocity, and pinch effect. The general belief that star light is the main ionizer is shown to be doubtful; hydromagnetic conversion of gravitational and kinetic energy may often be much more important. In Part II the revised plasma physics is applied to dark clouds and star formation. Magnetic fields do not necessarily counteract the contraction of a cloud; they may just as well 'pinch' the cloud. Magnetic compression may be the main mechanism for forming interstellar clouds and keeping them together. Part III treats the formation of stars in a dusty cosmic plasma cloud. Star formation is due to an instability, but it is very unlikely that it has anything to do with the Jeans instability. A reasonable mechanism is that the sedimentation of 'dust' (including solid bodies of different size) is triggering off a gravitationally assisted accretion. A 'stellesimal' accretion analogous to the planetesimal accretion leads to the formation of a star surrounded by a very low density hollow in the cloud. Matter falling in from the cloud towards the star is the raw material for the formation of planets and satellites.

  7. Cloud Optimized Image Format and Compression

    Becker, P.; Plesea, L.; Maurer, T.

    2015-04-01

    Cloud based image storage and processing requires revaluation of formats and processing methods. For the true value of the massive volumes of earth observation data to be realized, the image data needs to be accessible from the cloud. Traditional file formats such as TIF and NITF were developed in the hay day of the desktop and assumed fast low latency file access. Other formats such as JPEG2000 provide for streaming protocols for pixel data, but still require a server to have file access. These concepts no longer truly hold in cloud based elastic storage and computation environments. This paper will provide details of a newly evolving image storage format (MRF) and compression that is optimized for cloud environments. Although the cost of storage continues to fall for large data volumes, there is still significant value in compression. For imagery data to be used in analysis and exploit the extended dynamic range of the new sensors, lossless or controlled lossy compression is of high value. Compression decreases the data volumes stored and reduces the data transferred, but the reduced data size must be balanced with the CPU required to decompress. The paper also outlines a new compression algorithm (LERC) for imagery and elevation data that optimizes this balance. Advantages of the compression include its simple to implement algorithm that enables it to be efficiently accessed using JavaScript. Combing this new cloud based image storage format and compression will help resolve some of the challenges of big image data on the internet.

  8. Endogenous leukotriene formation during anaphylactic shock

    Keppler, A.; Oerning, L.; Bernstroem, K.; Hammarstroem, S.

    1987-01-01

    Leukotriene (LT)C 4 is a biologically active substance, presumed to play major roles as a mediator of allergic and anaphylactic reactions. It is formed e.g. by basophilic and eosinophilic leukocytes, monocytes, macrophages, and mast cells. In cells having IgE receptors, bridging of these by divalent anti-IgE-receptor antibodies or by interaction between receptor-bound IgE and anti-IgE will induce LTC 4 formation. Leukotriene formation has also been demonstrated in other in vitro models of immediate hypersensivity. The biological actions of LTC 4 , comprise induction of airway obstruction, constriction of coronary arteries, hypotension, and plasma extravasation. Leukotriene formation in vivo may mediate anaphylactic shock symptoms and cause the death of an animal. In order to prove the presumed mediator role of this substance in anaphylactic reactions, it is necessary to demonstrate its endogenous formation during shock. Studies on the metabolism of LTC 4 have revealed rapid catabolism by various transformations of the peptide substituent. Recently, three metabolites were demonstrated to be excreted as end-products in man (LTE 4 ,) and the rat (N-acetyl LTE 4 and N-acetyl 11-trans LTE 4 ). By monitoring biliary N-acetyl LTE 4 levels, endogenous leukotriene formation in the rat was demonstrated in vivo after tissue trauma and endotoxin shock. We now wish to report evidence for endogenous leukotriene C 4 production during anaphylactic shock in guinea pigs. 37 refs. (author)

  9. Galaxy formation: internal mechanisms and cosmological processes

    Martig, Marie

    2010-01-01

    This thesis is devoted to galaxy formation and evolution in a cosmological context. Cosmological simulations have unveiled two main modes of galaxy growth: hierarchical growth by mergers and accretion of cold gas from cosmic filaments. However, these simulations rarely take into account small scale mechanisms, that govern internal evolution and that are a key ingredient to understand galaxy formation and evolution. Thanks to a new simulation technique that I have developed, I first studied the colors of galaxies, and in particular the reddening of elliptical galaxies. I showed that the gas disk in an elliptical galaxy could be stabilized against star formation because of the galaxy's stellar component being within a spheroid instead of a disk. This mechanism can explain the red colors of some elliptical galaxies that contain a gas disk. I also studied the formation of spiral galaxies: most cosmological simulations cannot explain the formation of Milky Way-like galaxies, i.e. with a large disk and a small bulge. I showed that this issue could be partly solved by taking into account in the simulations the mass loss from evolved stars through stellar winds, planetary nebulae and supernovae explosions. (author) [fr

  10. Crenarchaeal biofilm formation under extreme conditions.

    Andrea Koerdt

    Full Text Available BACKGROUND: Biofilm formation has been studied in much detail for a variety of bacterial species, as it plays a major role in the pathogenicity of bacteria. However, only limited information is available for the development of archaeal communities that are frequently found in many natural environments. METHODOLOGY: We have analyzed biofilm formation in three closely related hyperthermophilic crenarchaeotes: Sulfolobus acidocaldarius, S. solfataricus and S. tokodaii. We established a microtitre plate assay adapted to high temperatures to determine how pH and temperature influence biofilm formation in these organisms. Biofilm analysis by confocal laser scanning microscopy demonstrated that the three strains form very different communities ranging from simple carpet-like structures in S. solfataricus to high density tower-like structures in S. acidocaldarius in static systems. Lectin staining indicated that all three strains produced extracellular polysaccharides containing glucose, galactose, mannose and N-acetylglucosamine once biofilm formation was initiated. While flagella mutants had no phenotype in two days old static biofilms of S. solfataricus, a UV-induced pili deletion mutant showed decreased attachment of cells. CONCLUSION: The study gives first insights into formation and development of crenarchaeal biofilms in extreme environments.

  11. Fusomorphogenesis: cell fusion in organ formation.

    Shemer, G; Podbilewicz, B

    2000-05-01

    Cell fusion is a universal process that occurs during fertilization and in the formation of organs such as muscles, placenta, and bones. Very little is known about the molecular and cellular mechanisms of cell fusion during pattern formation. Here we review the dynamic anatomy of all cell fusions during embryonic and postembryonic development in an organism. Nearly all the cell fates and cell lineages are invariant in the nematode C. elegans and one third of the cells that are born fuse to form 44 syncytia in a reproducible and stereotyped way. To explain the function of cell fusion in organ formation we propose the fusomorphogenetic model as a simple cellular mechanism to efficiently redistribute membranes using a combination of cell fusion and polarized membrane recycling during morphogenesis. Thus, regulated intercellular and intracellular membrane fusion processes may drive elongation of the embryo as well as postembryonic organ formation in C. elegans. Finally, we use the fusomorphogenetic hypothesis to explain the role of cell fusion in the formation of organs like muscles, bones, and placenta in mammals and other species and to speculate on how the intracellular machinery that drive fusomorphogenesis may have evolved.

  12. Television Format As a Site of Cultural Negotiation: Studying the Structures, Agencies and Practices of Format Adaptation

    Keinonen, Heidi

    2016-01-01

    abstractDespite the growing number of publications on television formats, specific theorisations regarding formats and format adaptation, in particular, are still rare. In this article, I introduce a synthesizing approach for studying format appropriation. Drawing on format study, media industry

  13. What Do They Understand? Using Technology to Facilitate Formative Assessment

    Mitten, Carolyn; Jacobbe, Tim; Jacobbe, Elizabeth

    2017-01-01

    Formative assessment is so important to inform teachers' planning. A discussion of the benefits of using technology to facilitate formative assessment explains how four primary school teachers adopted three different apps to make their formative assessment more meaningful and useful.

  14. The role of formative feedback in promoting higher order thinking ...

    The role of formative feedback in promoting higher order thinking skills in ... activities, task characteristics, validating students' thinking, and providing feedback. ... Keywords: classroom environment, formative assessment, formative feedback, ...

  15. THE SPECIAL STATUS OF EXOGENOUS WORD-FORMATION WITHIN THE GERMAN WORD-FORMATION SYSTEM

    Zhilyuk Sergey Aleksandrovich

    2014-06-01

    Full Text Available The article presents the properties of exogenous word-formation system taking into account the existence of two word-formation systems in modern German. On the basis of foreign research which reveal modern trends in German word-formation connected with the internationalization and the development of new European Latin language. The author defines key features of exogenous word-formation, i.e. foreign origin of wordformation units, unmotivated units, unmotivated interchange in base and affixes as well as limited distribution rules in combination with German word-formation. The article analyzes various approaches to word-division, as well as motivated and unmotivated interchange of consonants in bases and in affixes. Unmotivated interchange showcases a special status of the exogenous word-formation within German. Another item covered by the article is the issue of confix. The article has opinions of researchers about correctness of its separation and a list of its features. The author presents his definition of confix: a confix is a bound exogenous word-formation unit with a certain lexical and semantic meaning and joining other units directly or indirectly (through linking morpheme -o-, which is able to make a base. Moreover, some confixes are able to participate at word-combination and have unlimited distribution. So far, confix showcases the integration of exogenous word-formation and traditional German word-formation. The research proves the special status of exogenous word-formation in German. Its results can be used as a base for further analysis of co-existing word-formation systems in German and determination of their characteristic features.

  16. Silver-Palladium Surfaces Inhibit Biofilm Formation

    Chiang, Wen-Chi; Schroll, Casper; Hilbert, Lisbeth Rischel

    2009-01-01

    Undesired biofilm formation is a major concern in many areas. In the present study, we investigated biofilm-inhibiting properties of a silver-palladium surface that kills bacteria by generating microelectric fields and electrochemical redox processes. For evaluation of the biofilm inhibition...... efficacy and study of the biofilm inhibition mechanism, the silver-sensitive Escherichia coli J53 and the silver-resistant E. coli J53[pMG101] strains were used as model organisms, and batch and flow chamber setups were used as model systems. In the case of the silver-sensitive strain, the silver......-palladium surfaces killed the bacteria and prevented biofilm formation under conditions of low or high bacterial load. In the case of the silver-resistant strain, the silver-palladium surfaces killed surface-associated bacteria and prevented biofilm formation under conditions of low bacterial load, whereas under...

  17. Formation enthalpy of alkali-borosilicate glass

    Borisova, N.V.; Ushakov, V.M.

    1991-01-01

    Temperature dependence of formation enthalpy of glass of the composition 0.0438Na 2 O-0.0385K 2 O-0.3394B 2 O 3 -0.5783SiO 2 was determined using the method of high-temperature colorimetry-dissolution, mixing and differential scanning calorimetry. The glass considered has liquation nature-two-vitrification ranges at 713 K and 817 K are detected. The brightening point is 922 K. The calculation of formation enthalpy using the method of partial heat capacities is made in the temperature range of 973-1473 K. Formation enthalpy does not depend on temperature in the temperature range of 298-1273 K

  18. Transmission Electron Microscopy Physics of Image Formation

    Kohl, Helmut

    2008-01-01

    Transmission Electron Microscopy: Physics of Image Formation presents the theory of image and contrast formation, and the analytical modes in transmission electron microscopy. The principles of particle and wave optics of electrons are described. Electron-specimen interactions are discussed for evaluating the theory of scattering and phase contrast. Also discussed are the kinematical and dynamical theories of electron diffraction and their applications for crystal-structure analysis and imaging of lattices and their defects. X-ray microanalysis and electron energy-loss spectroscopy are treated as analytical methods. Specimen damage and contamination by electron irradiation limits the resolution for biological and some inorganic specimens. This fifth edition includes discussion of recent progress, especially in the area of aberration correction and energy filtering; moreover, the topics introduced in the fourth edition have been updated. Transmission Electron Microscopy: Physics of Image Formation is written f...

  19. Formation of brine channels in sea ice.

    Morawetz, Klaus; Thoms, Silke; Kutschan, Bernd

    2017-03-01

    Liquid salty micro-channels (brine) between growing ice platelets in sea ice are an important habitat for CO 2 -binding microalgaea with great impact on polar ecosystems. The structure formation of ice platelets is microscopically described and a phase field model is developed. The pattern formation during solidification of the two-dimensional interstitial liquid is considered by two coupled order parameters, the tetrahedricity as structure of ice and the salinity. The coupling and time evolution of these order parameters are described by a consistent set of three model parameters. They determine the velocity of the freezing process and the structure formation, the phase diagram, the super-cooling and super-heating region, and the specific heat. The model is used to calculate the short-time frozen micro-structures. The obtained morphological structure is compared with the vertical brine pore space obtained from X-ray computed tomography.

  20. Deep learning for SAR image formation

    Mason, Eric; Yonel, Bariscan; Yazici, Birsen

    2017-04-01

    The recent success of deep learning has lead to growing interest in applying these methods to signal processing problems. This paper explores the applications of deep learning to synthetic aperture radar (SAR) image formation. We review deep learning from a perspective relevant to SAR image formation. Our objective is to address SAR image formation in the presence of uncertainties in the SAR forward model. We present a recurrent auto-encoder network architecture based on the iterative shrinkage thresholding algorithm (ISTA) that incorporates SAR modeling. We then present an off-line training method using stochastic gradient descent and discuss the challenges and key steps of learning. Lastly, we show experimentally that our method can be used to form focused images in the presence of phase uncertainties. We demonstrate that the resulting algorithm has faster convergence and decreased reconstruction error than that of ISTA.

  1. FORMATIVE AND REFLECTIVE MODELS IN MARKETING RESEARCH

    Claudia Ioana CIOBANU

    2017-06-01

    Full Text Available Compliance with the construct validity criteria is necessary for the correct assessment of the research in terms of quality and for further development of the marketing models. The identification of formative and reflective constructs as well as the correct testing of their validity and reliability are important methodological steps for marketing research as described in this article. The first part defines the reflective and the formative constructs and highlighst their particularities by analysing the theoretical criteria that differentiate them. In the second part of the study aspects of validity and trust for the formative and reflective constructs are presented as well as some empirical considerations from research literature regarding their measurement.

  2. Diverse Formation Mechanisms for Compact Galaxies

    Kim, Jin-Ah; Paudel, Sanjaya; Yoon, Suk-Jin

    2018-01-01

    Compact, quenched galaxies such as M32 are unusual ones located off the mass - size scaling relation defined by normal galaxies. Still, their formation mechanisms remain unsolved. Here we investigate the evolution of ~100 compact, quenched galaxies at z = 0 identified in the Illustris cosmological simulation. We identify three ways for a galaxy to become a compact one and, often, multiple mechanisms operate in a combined manner. First, stripping is responsible for making about a third of compact galaxies. Stripping removes stars from galaxies, usually while keeping their sizes intact. About one third are galaxies that cease their growth early on after entering into more massive, gigantic halos. Finally, about half of compact galaxies, ~ 35 % of which turn out to undergo stripping, experience the compaction due to the highly centrally concentrated star formation. We discuss the evolutionary path of compact galaxies on the mass – size plane for each mechanism in a broader context of dwarf galaxy formation and evolution.

  3. Stratigraphy and dissolution of the Rustler Formation

    Bachman, G.O.

    1985-01-01

    The Rustler Formation is the uppermost evaporite-bearing unit in the Permian Ochoan series in southeastern New Mexico. It rests on the Salado Formation which includes the salt beds where the mined facility for the Waste Isolation Pilot Plant (WIPP) is being constructed. An understanding of the physical stratigraphy of the Rustler Formation is pertinent to studies of the WIPP site because some portions of the Rustler are water-bearing and may provide paths for circulating waters to come into contact with, and dissolve, evaporites within the Ochoan sequence. Knowledge of the processes, magnitude, and history of evaporite dissolution in the vicinity of the WIPP site is important to an evaluation of the integrity of the site. 2 refs., 2 figs

  4. Forced migration, adolescence, and identity formation.

    Anagnostopoulos, Dimitris C; Vlassopoulos, Maria; Lazaratou, Helen

    2006-09-01

    Adolescence is a complex biopsychosocial phenomenon. All the inner-subjective changes in adolescents take place within the context of a specific social environment, which offers the necessary ideological setting that adolescents must confront in the course of their identity formation. Forced migration creates conditions under which the adolescent Ego may be traumatized more easily, resulting in the development of defensive mechanisms, which may interfere with the natural process of identity formation. The aim of this paper is to investigate how a traumatic situation such as forced migration may affect the mechanisms of identity formation in adolescence. For this purpose, clinical material, consisting of two cases of psychoanalytical psychotherapy of adolescents who were forced to immigrate to Greece, is presented and discussed in a psychoanalytical theoretical framework, along with the historical-sociological background.

  5. Protostar formation in the early universe.

    Yoshida, Naoki; Omukai, Kazuyuki; Hernquist, Lars

    2008-08-01

    The nature of the first generation of stars in the universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the standard theory for the growth of cosmic structure predicts that structures grow hierarchically through gravitational instability. We have developed an ab initio computer simulation of the formation of primordial stars that follows the relevant atomic and molecular processes in a primordial gas in an expanding universe. The results show that primeval density fluctuations left over from the Big Bang can drive the formation of a tiny protostar with a mass 1% that of the Sun. The protostar is a seed for the subsequent formation of a massive primordial star.

  6. The structure and formation of natural categories

    Fisher, Douglas; Langley, Pat

    1990-01-01

    Categorization and concept formation are critical activities of intelligence. These processes and the conceptual structures that support them raise important issues at the interface of cognitive psychology and artificial intelligence. The work presumes that advances in these and other areas are best facilitated by research methodologies that reward interdisciplinary interaction. In particular, a computational model is described of concept formation and categorization that exploits a rational analysis of basic level effects by Gluck and Corter. Their work provides a clean prescription of human category preferences that is adapted to the task of concept learning. Also, their analysis was extended to account for typicality and fan effects, and speculate on how the concept formation strategies might be extended to other facets of intelligence, such as problem solving.

  7. On the formation of ball lightning

    Silberg, P.A.

    1981-01-01

    A plasma continuum model for the formation of ball lightning is developed based on a substantial number of reports that the ball is often in the discharge column of a previous lightning stroke. The usual method of setting up the plasma equation for a one-component electron plasma is used. An approximate equation for the plasma is derived from the describing equation which is then solved exactly in terms of the Jacobi elliptic functions. The formation of the ball is based on a nonlinearity of the plasma equation which uner certain circumstances permits the field to collapse into a small region. This collapse is interpreted to be ball lightning. The approximate equation derived for the plasma has the same form as a previous equation used to describe the formation of the fireball plasma. (author)

  8. Heterotopic bone formation following total shoulder arthroplasty

    Kjaersgaard-Andersen, P.; Frich, Lars Henrik; Sjøbjerg, J.O.

    1989-01-01

    The incidence and location of heterotopic bone formation following total shoulder arthroplasty were evaluated in 58 Neer Mark-II total shoulder replacements. One year after surgery, 45% had developed some ectopic ossification. In six shoulders (10%) the ossifications roentgenographically bridged...... the glenohumeral and/or the glenoacromial space. There was no correlation between shoulder pain and the development of ossification. Shoulders with grade III heterotopic bone formation had a limited range of active elevation compared with shoulders without or with only a milder lesion. Men and patients...... with osteoarthritis of the shoulder joint were significantly disposed to the development of heterotopic bone. Heterotopic bone formation following total shoulder arthroplasty is frequent, but disabling heterotopic ossifications seem to be rare....

  9. String cavitation formation inside fuel injectors

    Reid, B. A.; Gavaises, M.; Mitroglou, N.; Hargrave, G. K.; Garner, C. P.; McDavid, R. M.

    2015-12-01

    The formation of vortex or ‘string’ cavitation has been visualised at pressures up to 2000 bar in an automotive-sized optical diesel fuel injector nozzle. The multi-hole nozzle geometry studied allowed observation of the hole-to-hole vortex interaction and, in particular, that of a bridging vortex in the sac region between the holes. Above a threshold Reynolds number, their formation and appearance during a 2 ms injection event was repeatable and independent of upstream pressure and cavitation number. In addition, two different hole layouts and threedimensional flow simulations have been employed to describe how, the relative positions of adjacent holes influenced the formation and hole-to-hole interaction of the observed string cavitation vortices, with good agreement between the experimental and simulation results being achieved.

  10. Planets around pulsars - Implications for planetary formation

    Bodenheimer, Peter

    1993-01-01

    Data on planets around pulsars are summarized, and different models intended to explain the formation mechanism are described. Both theoretical and observational evidence suggest that very special circumstances are required for the formation of planetary systems around pulsars, namely, the prior presence of a millisecond pulsar with a close binary companion, probably a low mass main-sequence star. It is concluded that the discovery of two planets around PSR 1257+12 is important for better understanding the problems of dynamics and stellar evolution. The process of planetary formation should be learned through intensive studies of the properties of disks near young objects and application of techniques for detection of planets around main-sequence solar-type stars.

  11. Chondroitin Sulfate Perlecan Enhances Collagen Fibril Formation

    Kvist, A. J.; Johnson, A. E.; Mörgelin, M.

    2006-01-01

    in collagen type II fibril assembly by perlecan-null chondrocytes. Cartilage perlecan is a heparin sulfate or a mixed heparan sulfate/chondroitin sulfate proteoglycan. The latter form binds collagen and accelerates fibril formation in vitro, with more defined fibril morphology and increased fibril diameters...... produced in the presence of perlecan. Interestingly, the enhancement of collagen fibril formation is independent on the core protein and is mimicked by chondroitin sulfate E but neither by chondroitin sulfate D nor dextran sulfate. Furthermore, perlecan chondroitin sulfate contains the 4,6-disulfated...... disaccharides typical for chondroitin sulfate E. Indeed, purified glycosaminoglycans from perlecan-enriched fractions of cartilage extracts contain elevated levels of 4,6-disulfated chondroitin sulfate disaccharides and enhance collagen fibril formation. The effect on collagen assembly is proportional...

  12. Creating and maintaining a gas cap in tar sands formations

    Vinegar, Harold J.; Karanikas, John Michael; Dinkoruk, Deniz Sumnu; Wellington, Scott Lee

    2010-03-16

    Methods for treating a tar sands formation are disclosed herein. Methods for treating a tar sands formation may include providing heat to at least part of a hydrocarbon layer in the formation from one or more heaters located in the formation. Pressure may be allowed to increase in an upper portion of the formation to provide a gas cap in the upper portion. At least some hydrocarbons are produced from a lower portion of the formation.

  13. Some remarks on word formation in Danish

    Götzsche, Hans

    Abstract for the 25th Scandinavian Conference of Linguistics Some remarks on wordformation in Danish Some Danish word formation phenomena pose a problem for the linguist, being a predicament for analysis. In Danish a train leaves the station when it afgår ‘leaves’, while a minister may gå af......, there are some patterns for these Danish compounds concerning their internal semantics, in that the same lexical items may be used for different purposes depending on whether they are formed as a straightforward linear sequence (a word formation) or a reversed sequence (a phrase). The problem is (i) how the two...

  14. Pratiques sociales en formation à distance

    Clément Dussarps

    2015-10-01

    Full Text Available L’abandon en formation ouverte et à distance (FOAD constitue un enjeu important tant pour les apprenants que pour les organismes de formation, que ce soit pour des raisons économiques, sociales, ou encore d’image de soi ou publique (Sauvé, 2012. L’un des éléments clés de l’abandon semble être la solitude vécue par les apprenants (Glikman, 2002, p. 242. Ce sentiment de solitude et l’abandon semblent peu dépendants de facteurs socio-démographiques (sexe, âge, etc. (Park et Choi, 2009. Face...

  15. Research of Self-Formation Nanostructures

    Romas Petrauskas

    2011-08-01

    Full Text Available Lateral etching processes for the modeling of the geometry of self-formation nanostructures with Silvaco TCAD Athena program are analyzed. Self-formation nanostructures is modeled with different mask selectivity values equal to 2, 10, 40 and 100 with respect to the etching layer, with the etching duration of 0–180 s. The etching rates are constant – 1.33 nm/s. The analysis of the dependence of the etching systematic error on its thickness has been carried out. The computer modeled results are close to the ones produced by means of the application of the analytical calculation models by other authors.Article in Lithuanian

  16. Process for recovering oil from subterranean formations

    Knight, B.; Gogarty, W.B.

    1978-01-01

    Improved flooding of oil-bearing formations is obtained by injecting and displacing through the formation a saline solution containing a water-soluble, substantially linear, high molecular weight polymer obtained by irradiating an aqueous solution of an ethylenically unsaturated monomer and a water-soluble salt under controlled conditions of concentration, radiation intensity, conversion, and total radiation dose. The saline water can contain at least 15,000 ppm of TDS (total dissolved solids) and at least 50 ppm and preferably 300 ppm of polyvalent cations. (Auth.)

  17. Apparatus for consolidation of earth formations

    Brandt, H

    1968-02-08

    Earth formations are consolidated by injecting into the formation a fluid medium through vertically spaced perforations; a device lowered into the borehole permits creating chambers isolated from each other and communicating with only one, or a group of perforations. These chambers are connected through valved conduits to a reservoir of the consolidating medium. Each chamber or each group of chambers has its own supply conduit, and flow-measuring means are provided in each conduit. The valves may be magnetic valves, controlled electrically from the surface; the reservoirs for the consolidating medium may be equipped with hydraulically actuated pistons. (8 claims)

  18. Multilevel Modulation formats for Optical Communication

    Jensen, Jesper Bevensee

    2008-01-01

    This thesis studies the use of multilevel modulation formats for optical communication systems. Multilevel modulation is an attractive method of increasing the spectral efficiency of optical communication systems. Various modulation formats employing phase modulation, amplitude modulation...... or a combination of the two have been studied. The use of polarization multiplexing (PolMux) to double the bit rate has also been investigated. The impact of transmission impairments such as chromatic dispersion, self phase modulation and cross phase modulation has been investigated. The feasibility of multilevel...... modulation for network oriented scenarios has been demonstrated....

  19. Creating fluid injectivity in tar sands formations

    Stegemeier, George Leo; Beer, Gary Lee; Zhang, Etuan

    2010-06-08

    Methods for treating a tar sands formation are described herein. Methods for treating a tar sands may include heating a portion of a hydrocarbon layer in the formation from one or more heaters located in the portion. The heat may be controlled to increase the permeability of at least part of the portion to create an injection zone in the portion with an average permeability sufficient to allow injection of a fluid through the injection zone. A drive fluid and/or an oxidizing fluid may be provided into the injection zone. At least some hydrocarbons are produced from the portion.

  20. Landscape-geochemical factors of deposit formation

    Batulin, S.G.

    1980-01-01

    Effect of landscape-geochemical factors on hydrogenic formation of uranium ores is considered. The primary attention is paid to finding reasons for hydrogeochemical background increase in the regions of arid climate. Problems of uranium distribution in alluvial landscapes, hydrogeochemical regime of ground waters, reflecting the effect of waters of the zone of aeration are revealed. Chemical composition of porous solutions in the zone of aeration, as well as historical geochemindstry of landscape a its role from the view point of uranium solution formation in the arid zone are considered [ru

  1. Fluid Density and Impact Cavity Formation

    Ga-Chun Lin

    2018-01-01

    Full Text Available Characteristics of the impact cavity formed when a steel ball is dropped into aqueous solutions of densities ranging from 0.98 g·cm-3 to 1.63 g·cm-3 were investigated. A high-speed camera was used to record the formation and collapse of the cavity. The results showed cavity diameter, volume, and pinch-off time are independent of fluid density, on average. There was an unexplained reduction in cavity formation for densities of 1.34 g·cm-3 and 1.45 g·cm-3.

  2. Functions in Free-Format RPG IV

    Martin, Jim

    2009-01-01

    Written especially for programmers adopting a free-format style, this manual explores the role of functions in writing RPG IV programs. Demonstrating the potential of functions, many topics are explored such as details about existing RPG IV built-in functions, writing new functions, using ILE concepts to use C functions, and utilizing IBM API's functions. Explaining how to write small programs, either as sub-procedures or modules, and how to gather those parts together to make programs that are easy to write and maintain, this is a natural next step for programmers familiar with a free-format

  3. [Formation of nitrosamines in cheese products].

    Klein, D; Keshavarz, A; Lafont, P; Hardy, J; Debry, G

    1980-01-01

    Several strains of micromycetes used as fermentation agents in the cheese industry or having led to accidents during cheese making are able to favor the formation of nitrosamines in 60% of the cases. The concentrations observed are similar to those found by other authors with other microorganisms. The results obtained in a semi-synthetic medium are checked during the ripening of experimental camembert type cheese made from milk containing nitrates and cultured with a strain of Penicillium camemberti, which favors very much the synthesis of nitrosamines. The amount of nitrosodimethylamine formed in this cheese increases from 5 to 20 ppb during ripening. A tentative explanation of the mechanism of formation is outlined.

  4. Parallel heater system for subsurface formations

    Harris, Christopher Kelvin [Houston, TX; Karanikas, John Michael [Houston, TX; Nguyen, Scott Vinh [Houston, TX

    2011-10-25

    A heating system for a subsurface formation is disclosed. The system includes a plurality of substantially horizontally oriented or inclined heater sections located in a hydrocarbon containing layer in the formation. At least a portion of two of the heater sections are substantially parallel to each other. The ends of at least two of the heater sections in the layer are electrically coupled to a substantially horizontal, or inclined, electrical conductor oriented substantially perpendicular to the ends of the at least two heater sections.

  5. Pattern formation in Pseudomonas aeruginosa biofilms

    Parsek, Matthew R.; Tolker-Nielsen, Tim

    2008-01-01

    Bacteria are capable of forming elaborate multicellular communities called biofilms. Pattern formation in biofilms depends on cell proliferation and cellular migration in response to the available nutrients and other external cues, as well as on self-generated intercellular signal molecules...... and the production of an extracellular matrix that serves as a structural 'scaffolding' for the biofilm cells. Pattern formation in biofilms allows cells to position themselves favorably within nutrient gradients and enables buildup and maintenance of physiologically distinct subpopulations, which facilitates...... survival of one or more subpopulations upon environmental insult, and therefore plays an important role in the innate tolerance displayed by biofilms toward adverse conditions....

  6. Formation and decay of hot nuclei

    Tamain, B.

    1992-09-01

    The mechanisms involved in hot nuclei formation and decay and their eventual connexion with fundamental properties of nuclear matter are discussed, i.e. its equation of state is considered. After a brief review of the reactions in which hot nuclei can be formed, the variables which are used to describe them, the corresponding theoretical descriptions and their limits when extreme states are reached are discussed. Experimental evidences for hot nuclei formation are presented, with the corresponding decay properties used as signatures. (R.P.) 64 refs.; 25 figs.; 2 tabs

  7. Formative assessment in mathematics for engineering students

    Ní Fhloinn, Eabhnat; Carr, Michael

    2017-07-01

    In this paper, we present a range of formative assessment types for engineering mathematics, including in-class exercises, homework, mock examination questions, table quizzes, presentations, critical analyses of statistical papers, peer-to-peer teaching, online assessments and electronic voting systems. We provide practical tips for the implementation of such assessments, with a particular focus on time or resource constraints and large class sizes, as well as effective methods of feedback. In addition, we consider the benefits of such formative assessments for students and staff.

  8. Aromatics oxidation and soot formation in flames

    Howard, J.B.; Pope, C.J.; Shandross, R.A.; Yadav, T. [Massachusetts Institute of Technology, Cambridge (United States)

    1993-12-01

    This project is concerned with the kinetics and mechanisms of aromatics oxidation and soot and fullerenes formation in flames. The scope includes detailed measurements of profiles of stable and radical species concentrations in low-pressure one-dimensional premixed flames. Intermediate species identifications and mole fractions, fluxes, and net reaction rates calculated from the measured profiles are used to test postulated reaction mechanisms. Particular objectives are to identify and to determine or confirm rate constants for the main benzene oxidation reactions in flames, and to characterize fullerenes and their formation mechanisms and kinetics.

  9. Radio continuum, far infrared and star formation

    Wielebinski, R.; Wunderlich, E.; Klein, U.; Hummel, E.

    1987-01-01

    A very tight correlation was found between the radio emission and the far infrared emission from galaxies. This has been found for various samples of galaxies and is explained in terms of recent star formation. The tight correlation would imply that the total radio emission is a good tracer of star formation. The correlation between the radio power at 5 GHz and the far infrared luminosity is shown. The galaxies are of various morphological types and were selected from the various IRAS circulars, hence the sample is an infrared selected sample. The far infrared luminosities were corrected for the dust temperature. This is significant because it decreases the dispersion in the correlation

  10. Value Formation of Basic Anthropological Connectivities

    Bertelsen, Preben

    2009-01-01

    and their political value formations. In this regard, the interdisciplinary contribution of Psychology is to explore how humans as active participants can and will participate in handling such value tasks. The article presents a general, theoretical, political-psychological model, which unites precisely these two......Abstract. Human beings live and thrive in surroundings based on the human condition of certain basic anthropological connectivities. Amongst the vital political life tasks can be mentioned the ones of establishing, maintaining and critically/conformably developing these basic conditions...... aspects: The political value formations of the basic anthropological conditions in human life, and the capability and will to participate in solving the subsequent value tasks....

  11. [Mechanisms of leukocyte formation of endogenous pyrogen].

    Rybakina, E G; Sorokin, A V

    1982-06-01

    A study was made of the kinetics of endogenous pyrogen production by rabbit blood and exudate leukocytes and possible role played by the products of activated leukocytes in autoregulation of the process. It was established that accumulation of endogenous pyrogen in the cell precedes its release by stimulated cells. Then the processes of active pyrogen formation and release gel interdependent: pyrogen formed releases from the cell; the lowering of pyrogen concentration in the cell is accompanied by the decrease of its content in the medium. No stimulating effect of the products activated during leukocyte inflammation on pyrogen formation by blood leukocytes was discovered.

  12. No effect of steroids on seroma formation after mastectomy

    Okholm, Mette; Axelsson, Christen Kirk

    2011-01-01

    Seroma formation is a common problem after breast surgery. Studies indicate that seroma formation is a result of the postoperative inflammatory process. Glucocorticoid inhibits the inflammatory response....

  13. FORMATION OF PROFESSIONAL MOBILITY SPECIALIST WITHIN THE COMPETENCE APPROACH

    M. L. Gruzdeva

    2013-01-01

    Full Text Available In the article discussed the question of formation of professional mobility specialist through the formation of professional competencies within the educational process in high school.

  14. Solubility studies of oxovanadium(V) formate and vanadyl formate in aqueous medium

    Tripathi, V.S.; Bairwa, K.K.; Naik, D.B.; Raje, N.H.; Bera, S.

    2014-01-01

    The solubility of oxovanadium(V) formate and vanadyl formate in aqueous medium has been determined. These compounds are important for preparation of strong reducing V(II) compounds which are used in stainless steel based nuclear power plants for decontamination

  15. [Lipids from fossil plants and their relation to modern plants. Example s of Cenomanian flora from Anjou and Bohemia].

    Thanh, T N; Derenne, S; Largeau, C; Pons, D; Broutin, J; Mariotti, A; Bocherens, H

    2000-01-01

    Comparative analyses of lipids from fossil plants and from their extant counterparts were undertaken in order to test the taxonomic significance of lipids in palaeobotany. The comparison between lipids from a fossil Ginkgoaceae, Eretmophyllum andegavense, and its extant counterpart, Ginkgo biloba, revealed the presence of original molecules, dimethoxyalkylcoumarins, in lipids from both plants. Such compounds confirm, on chemical grounds the relationship between these extant and fossil Ginkgoaceaes. Moreover, differences in n-alkane distribution between E. andegavense and E. obtusum which are very similar morphologically, confirm that these fossil plants do not belong to the same species. Furthermore, comparative analyses of a fossil Cheirolepidiaceae, Frenelopsis alata, and its extant counterpart, the Cupressaceae Tetraclinis articulata, revealed some similarities between these two species although they do not belong to the same family. Otherwise, comparative analyses of fungi-infected and uninfected samples of F. alata demonstrated that these micro-organisms can significantly affect the chemical composition of fossil plant lipids. In conclusion, even if chemical analyses alone are not sufficient to determine the genus or species of a given fossil plant, they can precise the taxonomy of some specimens that have been previously studied by palaeobotanists.

  16. Formation Design Strategy for SCOPE High-Elliptic Formation Flying Mission

    Tsuda, Yuichi

    2007-01-01

    The new formation design strategy using simulated annealing (SA) optimization is presented. The SA algorithm is useful to survey a whole solution space of optimum formation, taking into account realistic constraints composed of continuous and discrete functions. It is revealed that this method is not only applicable for circular orbit, but also for high-elliptic orbit formation flying. The developed algorithm is first tested with a simple cart-wheel motion example, and then applied to the formation design for SCOPE. SCOPE is the next generation geomagnetotail observation mission planned in JAXA, utilizing a formation flying techonology in a high elliptic orbit. A distinctive and useful heuristics is found by investigating SA results, showing the effectiveness of the proposed design process.

  17. Formation of hypertrophic scars: Evolution and susceptibility

    Mahdavian Delavary, B.; van der Veer, W.M.; Ferreira, J.A.; Niessen, F.B.

    2012-01-01

    Formation of hypertrophic scars is a common complication of wound healing, and at present little is known about the incidence and risk factors. Our aim was to analyse the incidence, progression, and regression of postoperative hypertrophic scars over time and to identify risk factors of hypertrophic

  18. Histopathology Predicts the Mechanism of Stone Formation

    Evan, Andrew P.

    2007-04-01

    About 5% of American women and 12% of men will develop a kidney stone at some time in their life and these numbers appear to be on the rise. Despite years of scientific research into the mechanisms of stone formation and growth, limited advances have been made until recently. Randall's original observations and thoughts on the mechanisms for kidney stone formation have been validated for idiopathic calcium oxalate stone formers (ICSF) but not for most other stone forming groups. Our current studies on selected groups of human stone formers using intraoperative papillary biopsies has shown overwhelming evidence for the presence of Randall's plaque in ICSF and that stone formation and growth are exclusively linked to its availability to urinary ions and proteins. Intense investigation of the plaque-stone junction is needed if we are to understand the factors leading to the overgrowth process on exposed regions of plaque. Such information should allow the development of treatment strategies to block stone formation in ICSF patients. Patients who form brushite stones, or who form apatite stones because of distal renal tubular acidosis (dRTA), or patients with calcium oxalate stones due to obesity bypass procedures, or patients with cystinuria, get plugged inner medullary collecting ducts (IMCD) which leads to total destruction of the lining cells and focal sites of interstitial fibrosis. These stone formers have plaque but at levels equal to or below non-stone formers, which would suggest that they form stones by a different mechanism than do ICSF patients.

  19. Field observations of nearshore bar formation

    Aagaard, Troels; Kroon, Aart; Greenwood, Brian

    2008-01-01

      The formation of an inner nearshore bar was observed during a high-energy event at the sandy beach of Vejers, Denmark. The bar accreted in situ during surf zone conditions and the growth of the bar was associated with the development of a trough landward of the bar. Measurements of hydrodynamics...

  20. Interstellar clouds and the formation of stars

    Alfen, H.; Carlqvist, P.

    1977-12-01

    The 'pseudo-plasma formalism' which up to now has almost completely dominated theoretical astrophysics must be replaced by an experimentally based approach, involving the introduction of a number of neglected plasma phenomena, such as electric double layers, critical velocity, and pinch effect. The general belief that star light is the main ionizer is shown to be doubtful; hydromagnetic conversion of gravitational and kinetic energy may often be much more important. The revised plasma physics is applied to dark clouds and star formation. Magnetic fields do not necessarily counteract the contraction of a cloud, they may just as well 'pinch' the cloud. Magnetic compression may be the main mechanism for forming interstellar clouds and keeping them together. Star formation is due to an instability, but it is very unlikely that it has anything to do with the Jeans instablility. A reasonable mechanism is that the sedimentation of 'dust' (including solid bodies of different size) is triggering off a gravitationally assisted accretion. The study of the evolution of a dark cloud leads to a scenario of planet formation which is reconcilable with the results obtained from studies based on solar system data. This means that the new approach to cosmical plasma physics discussed logically leads to a consistent picture of the evolution of dark clouds and the formation of solar systems

  1. Studies of void formation in pure metals

    Lanore, J.M.; Glowinski, L.; Risbet, A.; Regnier, P.; Flament, J.L.; Levy, V.; Adda, Y.

    1975-01-01

    Recent experiments on the effect of gases on the final configuration of vacancy clustering (void or loop), and on the local effects at dislocations are described. The contribution of this data to a general knowledge of void formation will be discussed, and Monte Carlo calculations of swelling induced by irradiation with different particles presented [fr

  2. Dwarf galaxies : Important clues to galaxy formation

    Tolstoy, E

    2003-01-01

    The smallest dwarf galaxies are the most straight forward objects in which to study star formation processes on a galactic scale. They are typically single cell star forming entities, and as small potentials in orbit around a much larger one they are unlikely to accrete much (if any) extraneous

  3. Conformational Diffusion and Helix Formation Kinetics

    Hummer, Gerhard; Garcia, Angel E.; Garde, Shekhar

    2000-01-01

    The time, temperature, and sequence dependences of helix formation kinetics of fully atomistic peptide models in explicit solvent are described quantitatively by a diffusive search within the coil state with barrierless transitions into the helical state. Conformational diffusion leads to nonexponential kinetics and jump-width dependences in temperature jump experiments. (c) 2000 The American Physical Society

  4. The Formation of a Planetary Nebula.

    Harpaz, Amos

    1991-01-01

    Proposes a scenario to describe the formation of a planetary nebula, a cloud of gas surrounding a very hot compact star. Describes the nature of a planetary nebula, the number observed to date in the Milky Way Galaxy, and the results of research on a specific nebula. (MDH)

  5. Studies of void formation in pure metals

    Lanore, J.M.; Glowinski, L.; Risbet, A.; Regnier, P.; Flament, J.L.

    1975-01-01

    Recent experiments on the effect of gases on the final configuration of vacancy clustering (void or loop), and on the local effects at dislocations are described. The contribution of this data to our general knowledge of void formation will be discussed, and Monte Carlo calculations of swelling induced by irradiation with different particles presented

  6. Theory of ring formation around Be stars

    Huang, S.S.

    1976-01-01

    A quantitative theory has been developed for the formation of the gaseous rings around Be stars based on the ideas, first discussed by Gerasimovic, later developed by Huang, and independently suggested by Massa. The theory has been derived from the laws of conservation of energy and angular momentum without any other assumptions

  7. Formation, isomerization, and derivatization of keggin tungstoaluminates.

    Jennifer J. Cowan; Alan J. Bailey; Robert A. Heintz; Bao T. Do; Kenneth I. Hardcastle; Craig L. Hill; Ira A. Weinstock

    2001-01-01

    Trends in the stability of ¥á and ©¬-Keggin heteropolytungstates of the second-row main-group heteroatoms Al(III), Si(IV), and P(V) are elaborated by data that establish the roles of kinetic and thermodynamic control in the formation and isomerization of Keggin tungstoaluminates. Slow, room-temperature co-...

  8. Meteorological influences on coastal new particle formation

    Leeuw, G. de; Kunz, G.J.; Buzorius, G.; O`Dowd, C.D.

    2002-01-01

    The meteorological situation at the midlatitude coastal station of Mace Head, Ireland, is described based on observations during the New Particle Formation and Fate in the Coastal Environment (PARFORCE) experiments in September 1998 and June 1999. Micrometeorological sensors were mounted near the

  9. Essays on habit formation and inflation hedging

    Zhou, Y.

    2014-01-01

    The thesis consists of four chapters. Chapter 1 reviews recent contributions on habit formation in the literature and investigates its implications for investors. Chapter 2 revisits the “Floor-Leverage” rule for investors with ratchet consumption preference proposed by Scott and Watson (2011). It

  10. Formative Justice: The Regulative Principle of Education

    McClintock, Robert

    2016-01-01

    Background/Context: Concepts of justice relevant to making personal and public decisions about education. Purpose: To clarify a concept of formative justice that persons and the public often ignore in making decisions about educational effort. Setting: "The windmills of your mind" Research Design: Reflective essay.…

  11. Ectopic pancreas with pseudocyst and pseudoaneurysm formation

    Surov, A.; Hainz, M.; Hinz, L.; Holzhausen, H.-J.; Finke, R.; Spielmann, R.-P.; Kunze, C.

    2009-01-01

    Ectopic pancreas is a rare congenital anomaly. It is usually asymptomatic, or presents with non specific gastrointestinal symptoms. We describe here a case of ectopic pancreas in the gastric antrum, with pseudocyst and pseudoaneurysm formation. This entity has not been reported previously in the literature.

  12. Cu(II) promotes amyloid pore formation

    Zhang, Hangyu, E-mail: hangyuz@uw.edu [Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907 (United States); Rochet, Jean-Christophe [Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907 (United States); Stanciu, Lia A. [Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907 (United States); School of Materials Engineering, Purdue University, West Lafayette, IN 47907 (United States)

    2015-08-14

    The aggregation of α-synuclein is associated with dopamine neuron death in Parkinson's disease. There is controversy in the field over the question of which species of the aggregates, fibrils or protofibrils, are toxic. Moreover, compelling evidence suggested the exposure to heavy metals to be a risk of PD. Nevertheless, the mechanism of metal ions in promoting PD remains unclear. In this research, we investigated the structural basis of Cu(II) induced aggregation of α-synuclein. Using transmission electron microscopy experiments, Cu(II) was found to promote in vitro aggregation of α-synuclein by facilitating annular protofibril formation rather than fibril formation. Furthermore, neuroprotective baicalein disaggregated annular protofibrils accompanied by considerable decrease of β-sheet content. These results strongly support the hypothesis that annular protofibrils are the toxic species, rather than fibrils, thereby inspiring us to search novel therapeutic strategies for the suppression of the toxic annular protofibril formation. - Highlights: • Cu(II) promoted the annular protofibril formation of α-synuclein in vitro. • Cu(II) postponed the in vitro fibrillization of α-synuclein. • Neuroprotective baicalein disaggregated annular protofibrils.

  13. Teaching Tolerance? Associational Diversity and Tolerance Formation

    Rapp, Carolin; Freitag, Markus

    2015-01-01

    , a closer look is taken at how associational diversity relates to the formation of tolerance and the importance of associations as schools of tolerance are evaluated. The main theoretical argument follows contact theory, wherein regular and enduring contact in diverse settings reduces prejudice and thereby...

  14. Local induction of inflammation affects bone formation

    Croes, M; Kruyt, M C; Loozen, L; Kragten, A H; Yuan, H; Dhert, W J; Öner, F C; Alblas, J

    2017-01-01

    To explore the influence of inflammatory processes on bone formation, we applied a new in vivo screening model. Confined biological pockets were first created in rabbits as a response to implanted bone cement discs. These biomembrane pockets were subsequently used to study the effects of

  15. Memory, expectation formation and scheduling choices

    Koster, P.R.; Peer, S.; Dekker, T.

    2015-01-01

    Limited memory capacity, retrieval constraints and anchoring are central to expectation formation processes. We develop a model of adaptive expectations where individuals are able to store only a finite number of past experiences of a stochastic state variable. Retrieval of these experiences is

  16. Adaptive format conversion for scalable video coding

    Wan, Wade K.; Lim, Jae S.

    2001-12-01

    The enhancement layer in many scalable coding algorithms is composed of residual coding information. There is another type of information that can be transmitted instead of (or in addition to) residual coding. Since the encoder has access to the original sequence, it can utilize adaptive format conversion (AFC) to generate the enhancement layer and transmit the different format conversion methods as enhancement data. This paper investigates the use of adaptive format conversion information as enhancement data in scalable video coding. Experimental results are shown for a wide range of base layer qualities and enhancement bitrates to determine when AFC can improve video scalability. Since the parameters needed for AFC are small compared to residual coding, AFC can provide video scalability at low enhancement layer bitrates that are not possible with residual coding. In addition, AFC can also be used in addition to residual coding to improve video scalability at higher enhancement layer bitrates. Adaptive format conversion has not been studied in detail, but many scalable applications may benefit from it. An example of an application that AFC is well-suited for is the migration path for digital television where AFC can provide immediate video scalability as well as assist future migrations.

  17. Formation Sources of the Caspian ecosystems biodiversity

    G. A. Monakhova

    2009-01-01

    Full Text Available The existing ideas of the Caspian ecosystems biodiversity have been classified on the basis of data analysis and the main sources of its formation have been defined. They are different ways of flora and fauna originating combined with different mechanisms of water bodies’ isolation.

  18. Formation Sources of the Caspian ecosystems biodiversity

    G. A. Monakhova; G. M. Abdurakhmanov; G. A. Akhmedova

    2009-01-01

    The existing ideas of the Caspian ecosystems biodiversity have been classified on the basis of data analysis and the main sources of its formation have been defined. They are different ways of flora and fauna originating combined with different mechanisms of water bodies’ isolation.

  19. Formative assessment promotes learning in undergraduate clinical ...

    Introduction. Clinical clerkships, typically situated in environments lacking educational structure, form the backbone of undergraduate medical training. The imperative to develop strategies that enhance learning in this context is apparent. This study explored the impact of longitudinal bedside formative assessment on ...

  20. Mast cells mediate malignant pleural effusion formation.

    Giannou, Anastasios D; Marazioti, Antonia; Spella, Magda; Kanellakis, Nikolaos I; Apostolopoulou, Hara; Psallidas, Ioannis; Prijovich, Zeljko M; Vreka, Malamati; Zazara, Dimitra E; Lilis, Ioannis; Papaleonidopoulos, Vassilios; Kairi, Chrysoula A; Patmanidi, Alexandra L; Giopanou, Ioanna; Spiropoulou, Nikolitsa; Harokopos, Vaggelis; Aidinis, Vassilis; Spyratos, Dionisios; Teliousi, Stamatia; Papadaki, Helen; Taraviras, Stavros; Snyder, Linda A; Eickelberg, Oliver; Kardamakis, Dimitrios; Iwakura, Yoichiro; Feyerabend, Thorsten B; Rodewald, Hans-Reimer; Kalomenidis, Ioannis; Blackwell, Timothy S; Agalioti, Theodora; Stathopoulos, Georgios T

    2015-06-01

    Mast cells (MCs) have been identified in various tumors; however, the role of these cells in tumorigenesis remains controversial. Here, we quantified MCs in human and murine malignant pleural effusions (MPEs) and evaluated the fate and function of these cells in MPE development. Evaluation of murine MPE-competent lung and colon adenocarcinomas revealed that these tumors actively attract and subsequently degranulate MCs in the pleural space by elaborating CCL2 and osteopontin. MCs were required for effusion development, as MPEs did not form in mice lacking MCs, and pleural infusion of MCs with MPE-incompetent cells promoted MPE formation. Once homed to the pleural space, MCs released tryptase AB1 and IL-1β, which in turn induced pleural vasculature leakiness and triggered NF-κB activation in pleural tumor cells, thereby fostering pleural fluid accumulation and tumor growth. Evaluation of human effusions revealed that MCs are elevated in MPEs compared with benign effusions. Moreover, MC abundance correlated with MPE formation in a human cancer cell-induced effusion model. Treatment of mice with the c-KIT inhibitor imatinib mesylate limited effusion precipitation by mouse and human adenocarcinoma cells. Together, the results of this study indicate that MCs are required for MPE formation and suggest that MC-dependent effusion formation is therapeutically addressable.

  1. Plain formation on Mercury: tectonic implications

    Thomas, P.

    1980-01-01

    Four major plain units, plus intermediates, are distinguished on Mercury. The chronologic relationships between these plains indicate that plains formation was a permanent process on Mercury. Their location and morphology seem to indicate a possible volcanic origin for these plains. The relationships between tectonism and volcanism seems to indicate the global contraction is not the only tectonic process on Mercury. (Auth.)

  2. Tropospheric ozone. Formation, properties, effects. Expert opinion

    Elstner, E.F.

    1996-01-01

    The formation and dispersion of tropospheric ozone are discussed only marginally in this expert opinion; the key interest is in the effects of ground level ozone on plants, animals, and humans. The expert opinion is based on an analysis of the available scientific publications. (orig./MG) [de

  3. Cosmological Structure Formation: From Dawn till Dusk

    Heneka, Caroline Samantha

    Cosmology has entered an era where a plethora data is available on structure formation to constrain astrophysics and underlying cosmology. This thesis strives to both investigate new observables and modeling of the Epoch of Reionization, as well as to constrain dark energy phenomenology with mass......Cosmology has entered an era where a plethora data is available on structure formation to constrain astrophysics and underlying cosmology. This thesis strives to both investigate new observables and modeling of the Epoch of Reionization, as well as to constrain dark energy phenomenology...... with massive galaxy clusters, traveling from the dawn of structure formation, when the first galaxies appear, to its dusk, when a representative part of the mass in the Universe is settled in massive structures. This hunt for accurate constraints on cosmology is complemented with the demonstration of novel...... Bayesian statistical tools and kinematical constraints on dark energy. Starting at the dawn of structure formation, we study emission line fluctuations, employing semi-numerical simulations of cosmological volumes of their line emission, in order to cross-correlate fluctuations in brightness. This cross...

  4. Pathway of propionate formation in Desulfobulbus propionicus

    Stams, A.J.M.; Kremer, D.R.; Nicolaij, K.; Weenk, G.; Hansen, T.A.

    1984-01-01

    Whole cells of Desulfobulbus propionicus fermented [1-13C]ethanol to [2-13C] and [3-13C]propionate and [1-13C]-acetate, which indicates the involvement of a randomizing pathway in the formation of propionate. Cell-free extracts prepared from cells grown on lactate (without sulfate) contained high

  5. Group formation in early clinical project

    Østergaard, Gert Værge

    Research shows that getting involved is a key aspect of learning, and a way of getting involved is through study groups [1]. Forming groups are always a theme that is discussed, both amongst faculty and students. There is a different approach at different semesters regarding this formation...

  6. Teaching statistics in an activity encouraging format

    Knypstra, S.

    2009-01-01

    In a statistics course for bachelor students in econometrics a new format was adopted in which students were encouraged to study more actively and in which cooperative learning and peer teaching was implemented. Students had to work in groups of two or three students where each group had to perform

  7. Phase formation in contact of dissimilar metals

    Savvin, V S; Kazachkova, Yu A; Povzner, A A [Ural State Technical University-UPI, Mira st., 19, A-203, Yekaterinburg 620002 (Russian Federation)], E-mail: savvin-vs@yandex.ru

    2008-02-15

    Formation and growth of intermediate phases in contact of the crystalline samples forming a two-component eutectic system is considered. It is shown that during the competition to a growing liquid phase the intermediate solid phases cannot grow by diffusion. The alternative is formation of metastable areas of a liquid phase. Measurements of liquid layers extent in Pb-Bi and In-Bi systems have allowed to define the composition of liquid on interface where formation of metastable liquid is possible. The results show that the concentration interval of a liquid layer corresponds to a stable constitution diagram. In order to explain the experimental results the hypothesis according to which the intermediate solid phases are formed as a result of precipitation from metastable melt is considered. The experimental confirmation of formation and crystallization of a metastable liquid is the fact that intergrowth of the samples forming system with an intermetallic phase at temperatures below the temperature of fusion of the most low-melting eutectic is observed. The possibility of the processes concerned with the occurrence of metastable areas of a liquid is showed by means of computer imitation.

  8. Analcite formation in the Agades Region (Niger)

    1966-06-01

    A study based mainly upon field mapping and drill cores examination, followed by a laboratory survey allows us to support a genetic hypothesis upon the formation of analcime in the 'Continental intercalaire' of Agades (Niger). Analcime could be generated from an early diagenesis of argillaceous sediments influenced by high soda content fossil waters inside confined continental sedimentary basins. (authors) [fr

  9. Syndrome of shperical enlightement (cavitary formation)

    Ginzburg, M.A.

    1987-01-01

    Syndrome is characterized by spherical enlightement surrounded by a closed ring-shaped shadow. Such picture is created by the lung cavity. Intrasyndrome differential diagnosis of the cavitary formations in the lungs and differential diagnosis of restricted pneumothorax, intrapulmonary cavities are given. Ethiology, pathogenesis and pathomorphology of spherical enlightement syndrome, its clinical picture and investigation methods are discussed

  10. WORD FORMATION ON DRAGON NEST CHAT LANGUAGE

    Shavitri Cecillia Harsono

    2016-11-01

    Full Text Available Word formation is creation of new words, which sometimes changes a word’s meaning. Words can be formed from multi word phrases as well. In many cases vocabularies in language are formed from combination of words (Haspelmath 2010: 102. Word formation does not only involve changing physical form of the word itself, but also changing the meaning of said word. There are also instances where the physical form retain its original form while the meaning changes. The phenomenon is called semantic change (Stockwell-Minkova 2001:149. In this thesis the research proposed that the said phenomenon occur in virtual environment, such as in MMORPG. Multiplayer online games that feature fantasy setting virtual environment. For the purpose of this research, Dragon Nest South East Asia server was chosen as data source. The samples are taken from players perusing [World] communication channel. The result of the data analysis has shown that the phenomenon of word formation could occur in a virtual environment of MMORPG, specifcally in Dragon Nest SEA. There are two word formation processes found: processes that involve physical changes and processes that do not involve physical changes but rather innate meaning. It is done by both processing daily language vocabulary both physically and changing its innate meaning to create new words that suits the said virtual environment context. This fnding may influence future research on a fresh perspective and untilled feld.

  11. Theological Education and Character Formation in Nigerian ...

    This paper presents theological education and character formation in Nigerian Christianity. Some theologians and religious scholars do not offer any practical recipes in dealing with the major pressing problems of theological training for Christian ministry today in the 21st century Nigerian society. Some priests, lay workers ...

  12. Cu(II) promotes amyloid pore formation

    Zhang, Hangyu; Rochet, Jean-Christophe; Stanciu, Lia A.

    2015-01-01

    The aggregation of α-synuclein is associated with dopamine neuron death in Parkinson's disease. There is controversy in the field over the question of which species of the aggregates, fibrils or protofibrils, are toxic. Moreover, compelling evidence suggested the exposure to heavy metals to be a risk of PD. Nevertheless, the mechanism of metal ions in promoting PD remains unclear. In this research, we investigated the structural basis of Cu(II) induced aggregation of α-synuclein. Using transmission electron microscopy experiments, Cu(II) was found to promote in vitro aggregation of α-synuclein by facilitating annular protofibril formation rather than fibril formation. Furthermore, neuroprotective baicalein disaggregated annular protofibrils accompanied by considerable decrease of β-sheet content. These results strongly support the hypothesis that annular protofibrils are the toxic species, rather than fibrils, thereby inspiring us to search novel therapeutic strategies for the suppression of the toxic annular protofibril formation. - Highlights: • Cu(II) promoted the annular protofibril formation of α-synuclein in vitro. • Cu(II) postponed the in vitro fibrillization of α-synuclein. • Neuroprotective baicalein disaggregated annular protofibrils

  13. Star Formation in Merging Galaxies Using FIRE

    Perez, Adrianna; Hung, Chao-Ling; Naiman, Jill; Moreno, Jorge; Hopkins, Philip

    2018-01-01

    Galaxy interactions and mergers are efficient mechanisms to birth stars at rates that are significantly higher than found in our Milky Way galaxy. The Kennicut-Schmidt (KS) relation is an empirical relationship between the star-forming rate and gas surface densities of galaxies (Schmidt 1959; Kennicutt 1998). Although most galaxies follow the KS relation, the high levels of star formation in galaxy mergers places them outside of this otherwise tight relationship. The goal of this research is to analyze the gas content and star formation of simulated merging galaxies. Our work utilizes the Feedback In Realistic Environments (FIRE) model (Hopkins et al., 2014). The FIRE project is a high-resolution cosmological simulation that resolves star-forming regions and incorporates stellar feedback in a physically realistic way. In this work, we have noticed a significant increase in the star formation rate at first and second passage, when the two black holes of each galaxy approach one other. Next, we will analyze spatially resolved star-forming regions over the course of the interacting system. Then, we can study when and how the rates that gas converts into stars deviate from the standard KS. These analyses will provide important insights into the physical mechanisms that regulate star formation of normal and merging galaxies and valuable theoretical predictions that can be used to compare with current and future observations from ALMA or the James Webb Space Telescope.

  14. Galaxies interactions and induced star formation

    Kennicutt Jr, Robert C; Barnes, JE

    1998-01-01

    The papers that make up this volume present a comprehensive review of the field of galaxy interaction. Galaxies are dynamic forces that evolve, interact, merge, blaze and reshape. This book offers a historical perspective and studies such topics as induced star formation.

  15. Origin of comets - implications for planetary formation

    Weissman, P.R.; Arizona Univ., Tucson)

    1985-01-01

    Primordial and episodic theories for the origin of comets are discussed. The implications of the former type for the origin of the solar system are considered. Candidate sites for the formation of comets are compared. The possible existence of a massive inner Oort cloud is discussed

  16. Aspartate inhibits Staphylococcus aureus biofilm formation.

    Yang, Hang; Wang, Mengyue; Yu, Junping; Wei, Hongping

    2015-04-01

    Biofilm formation renders Staphylococcus aureus highly resistant to conventional antibiotics and host defenses. Four D-amino acids (D-Leu, D-Met, D-Trp and D-Tyr) have been reported to be able to inhibit biofilm formation and disassemble established S. aureus biofilms. We report here for the first time that both D- and L-isoforms of aspartate (Asp) inhibited S. aureus biofilm formation on tissue culture plates. Similar biofilm inhibition effects were also observed against other staphylococcal strains, including S. saprophyticus, S. equorum, S. chromogenes and S. haemolyticus. It was found that Asp at high concentrations (>10 mM) inhibited the growth of planktonic N315 cells, but at subinhibitory concentrations decreased the cellular metabolic activity without influencing cell growth. The decreased cellular metabolic activity might be the reason for the production of less protein and DNA in the matrix of the biofilms formed in the presence of Asp. However, varied inhibition efficacies of Asp were observed for biofilms formed by clinical staphylococcal isolates. There might be mechanisms other than decreasing the metabolic activity, e.g. the biofilm phenotypes, affecting biofilm formation in the presence of Asp. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Palladium-Catalyzed Asymmetric Quaternary Stereocenter Formation

    Gottumukkala, Aditya L.; Matcha, Kiran; Lutz, Martin; de Vries, Johannes G.; Minnaard, Adriaan J.

    2012-01-01

    An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of beta,beta-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF6, and

  18. Palladium-catalyzed asymmetric quaternary stereocenter formation

    Gottumukkala, A.L.; Matcha, K.; Lutz, M.; de Vries, J.G.; Minnaard, A.J.

    2012-01-01

    An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of β,β-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF6, and provides

  19. Condensation and frost formation in heat exchangers

    Rostami, A.A.

    1982-01-01

    The occurence of condensation and of frost formation are considered for air to heat exchangers with emphasis on how such occurrences would affect the performance of such heat exchangers when they are used in ventilating applications. The formulations which predict performance are developed for parallel, counter flow and cross flow with either formation or condensation, and for condensation the consequences for evaporation of condensate and of the effect of longitudinal conduction in the walls of the exchanger are also considered. For the prediction of the exchanger performance with frost formation there must be specified the growth of the frost layer with time and existing theories for this growth are examined, a new method of calculation of the growth is presented and this is shown to give results for the growth that are in accord with available experimental evidence. This new theory for the growth of a frost layer is used to predict the performance of a parallel flow exchanger under conditions in which frost formation occurs, by successively applying the steady state performance calculation for time increments over which the frost layer build-up is calculated for these time increments. The calculation of counter flow exchanger performance by this method, while feasible, is so time consuming that only the general aspects of the calculation are considered

  20. Directed networks, allocation properties and hierarchy formation

    Slikker, M.; Gilles, R.P.; Norde, H.W.; Tijs, S.H.

    2005-01-01

    We investigate properties for allocation rules on directed communication networks and the formation of such networks under these payoff properties. We study allocation rules satisfying two appealing properties, Component Efficiency (CE) and the Hierarchical Payoff Property (HPP). We show that such