Sample records for triassic time scale

  1. Time-scale calibration by U-Pb geochronology: Examples from the Triassic Period

    NASA Astrophysics Data System (ADS)

    Mundil, R.

    2009-05-01

    U-Pb zircon geochronology, pioneered by Tom Krogh, is a cornerstone for the calibration of the time scale. Before Krogh's innovations, U-Pb geochronology was essentially limited by laboratory blank Pb (typically hundreds of nanograms) inherent in the then existing zircon dissolution and purification methods. The introduction of high pressure HF dissolution combined with miniature ion exchange columns (1) reduced the blank by orders of magnitude and allowed mass-spectrometric analyses of minute amounts of material (picograms of Pb and U). Krogh also recognized the need for minimizing the effects of Pb loss, and the introduction of the air-abrasion technique was the method of choice for two decades (2), until the development of the combined annealing and chemical abrasion technique resulted in essentially closed system zircons (3). These are the prerequisite for obtaining precise (permil-level) and accurate radio-isotopic ages of individual zircons contained in primary volcanic ash deposits, which are primary targets for the calibration of the time scale if they occur within fossil bearing sediments. A prime example is the calibration of the Triassic time scale which improved significantly using these techniques. The ages for the base and the top of the Triassic are constrained by U-Pb ages to 252.3 (4) and 201.5 Ma (5), respectively. These dates also constrain the ages of major extinction events at the Permian-Triassic and Triassic-Jurassic boundaries, and are statistically indistinguishable from ages obtained for the Siberian Traps and volcanic products from the Central Atlantic Magmatic Province, respectively, suggesting a causal link. Ages for these continental volcanics, however, are mostly from the K-Ar (40Ar/39Ar) system which requires accounting and correcting for a systematic bias of ca 1 % between U-Pb and 40Ar/39Ar isotopic ages (the 40Ar/39Ar ages being younger) (6). Robust U-Pb age constraints also exist for the Induan- Olenekian boundary (251.2 Ma, (7)) and the Early-Middle Triassic (Olenekian-Anisian) boundary (247.2 Ma, (8, 9)), resulting in a surprisingly short duration of the Early Triassic which has implications for the timing of biotic recovery and major changes in ocean chemistry during this time. Furthermore, the Anisian-Ladinian boundary is constrained to 242.0 Ma by new U-Pb and 40Ar/39Ar ages. Radio-isotopic ages for the Late Triassic are scarce and the only reliable and biostratigraphically controlled age is from an upper Carnian tuff dated to 230.9 Ma (10), yielding a duration of more than 35 Ma for the Late Triassic. The resulting time-scale is at odds with the most recent compilation (11) but arguably more accurate because it is entirely based on U-Pb analyses applied to closed-system zircons with uncertainties at the permil level or better. 1. T. E. Krogh, Geochimica et Cosmochimica Acta 37, 485 (1973); 2. T. E. Krogh, Geochimica et Cosmochimica Acta 46, 637 (1982); 3. J. M. Mattinson, Chemical Geology 220, 47 (2005); 4. R. Mundil, K. R. Ludwig, I. Metcalfe, P. R. Renne, Science 305, 1760 (2004); 5. U. Schaltegger, J. Guex, A. Bartolini, B. Schoene, M. Ovtcharova, Earth and Planetary Science Letters 267, 266 (2008); 6. R. Mundil, P. R. Renne, K. K. Min, K. R. Ludwig, in Eos Trans. AGU, Fall Meet. Suppl. (2006), vol. 87(52), pp. V21A-0543; 7. T. Galfetti et al., Earth and Planetary Science Letters 258, 593 (2007). 8. M. Ovtcharova et al., Earth and Planetary Science Letters 243, 463 (2006). 9. J. Ramezani et al., Earth and Planetary Science Letters 256, 244 (2007). 10. S. Furin et al., Geology 34, 1009 (2006); 11. J. G. Ogg, in A Geologic Time Scale 2004 F. M. Gradstein, J. G. Ogg, A. G. Smith, Eds. (University Press, Cambridge, 2004) pp. 271-306.

  2. Magnetostratigraphic dating of the proposed Rhaetian GSSP at Steinbergkogel (Upper Triassic, Austria): Implications for the Late Triassic time scale

    E-print Network

    Utrecht, Universiteit

    by cyclostratigraphic control on the marine Pizzo Mondello (Italy) section, where a combination of long period The Late Triassic period is characterized by increasingenvironmental stress that eventually culminated and Rhaetian stages. The GSSP defining the base of the Hettangian (base Jurassic) was formally accepted by ICS

  3. The late Permian\\/early Triassic magnetic polarity time scale and plate motions of south China

    Microsoft Academic Search

    M. Steiner; J. Ogg; Z. Zhang; S. Sun

    1989-01-01

    Fossiliferous stratigraphic sections spanning the Permian-Triassic boundary in south China have yielded a well-defined magnetic polarity sequence for the Lower Triassic and a more poorly defined sequence in the upper Permian. Four sections comprising more than 1100 continuous meters of stratigraphic section display a sequence of 11 major reversals of polarity within the Early Triassic (Griesbachian to Sapthian stages) and

  4. High-precision U-Pb zircon geochronological constraints on the End-Triassic Mass Extinction, the late Triassic Astronomical Time Scale and geochemical evolution of CAMP magmatism

    NASA Astrophysics Data System (ADS)

    Blackburn, T. J.; Olsen, P. E.; Bowring, S. A.; McLean, N. M.; Kent, D. V.; Puffer, J. H.; McHone, G.; Rasbury, T.

    2012-12-01

    Mass extinction events that punctuate Earth's history have had a large influence on the evolution, diversity and composition of our planet's biosphere. The approximate temporal coincidence between the five major extinction events over the last 542 million years and the eruption of Large Igneous Provinces (LIPs) has led to the speculation that climate and environmental perturbations generated by the emplacement of a large volume of magma in a short period of time triggered each global biologic crisis. Establishing a causal link between extinction and the onset and tempo of LIP eruption has proved difficult because of the geographic separation between LIP volcanic deposits and stratigraphic sequences preserving evidence of the extinction. In most cases, the uncertainties on available radioisotopic dates used to correlate between geographically separated study areas often exceed the duration of both the extinction interval and LIP volcanism by an order of magnitude. The "end-Triassic extinction" (ETE) is one of the "big five" and is characterized by the disappearance of several terrestrial and marine species and dominance of Dinosaurs for the next 134 million years. Speculation on the cause has centered on massive climate perturbations thought to accompany the eruption of flood basalts related to the Central Atlantic Magmatic Province (CAMP), the most aerially extensive and volumetrically one of the largest LIPs on Earth. Despite an approximate temporal coincidence between extinction and volcanism, there lacks evidence placing the eruption of CAMP prior to or at the initiation of the extinction. Estimates of the timing and/or duration of CAMP volcanism provided by astrochronology and Ar-Ar geochronology differ by an order of magnitude, precluding high-precision tests of the relationship between LIP volcanism and the mass extinction, the causes of which are dependent upon the rate of magma eruption. Here we present high precision zircon U-Pb ID-TIMS geochronologic data for eight CAMP flows and sills from the eastern U.S. and Morocco. These data are used first to independently test the astronomically calibrated time scale and sediment accumulation rates within the Triassic-Jurassic rift basins along the eastern North America. The U-Pb, paleontological, magnetostratigraphic and astronomical data are combined to constrain the onset and duration of the CAMP and clarify the temporal relationship between the CAMP and the ETE. The dataset together allows more precise estimates of eruptive volume per unit time, a requirement for rigorous evaluation of climate-driven models for the extinction.

  5. Early Triassic magnetic polarity time scale—integration of magnetostratigraphy, ammonite zonation and sequence stratigraphy from stratotype sections (Canadian Arctic Archipelago)

    NASA Astrophysics Data System (ADS)

    Ogg, James G.; Steiner, Maureen B.

    1991-10-01

    Stratotypes defining the stages of the Early Triassic (Griesbachian, Dienerian, Smithian and Spathian) are located on Ellesmere and Axel Heiberg islands in the northern Canadian Arctic. Ammonite-rich horizons are within a clastic outer shelf-to-slope facies of thick progradational wedges of mudstones and siltstones. Three sections were sampled for magnetostratigraphy and interpreted for transgressive and regressive pulses of sedimentation. Using the ammonite zonation as a guide, the transgressive-regressive cycles and magnetostratigraphies have been correlated among the sections and to the published Triassic sequence stratigraphy time scale, thus enabling definition of the magnetic polarity pattern for the upper Griesbachian to Smithian stages in multiple sections. The magnetic polarity and associated sequence stratigraphy pattern for the lower Griesbachian and for the Spathian were derived from single sections. The Griesbachian and Dienerian stages each have two pairs of normal- and reversed-polarity chrons; the Smithian is predominantly of normal polarity, and the Spathian is predominantly of reversed polarity. This magnetic polarity time scale may help to resolve age correlations of North American redbed facies and to define the Permian-Triassic boundary. After correction for variable structural orientations, the mean directions of magnetization from the three sites converge at 296° declination, 57° inclination ( k = 60, ? 95 = 16.5° ; equivalent pole = 41°N, 161°E; paleolatitude = 38°N), which is consistent with the pole derived from nearby Early Permian volcanics and supports a postulated post-Early Triassic, pre-Tertiary counterclockwise rotation of this region with respect to cratonic North America.

  6. Testing the fossil record: Sampling proxies and scaling in the British TriassicJurassic

    E-print Network

    Benton, Michael

    Testing the fossil record: Sampling proxies and scaling in the British Triassic­Jurassic Alexander March 2014 Available online 30 March 2014 Keywords: Palaeodiversity Fossil record Sampling Proxy Triassic Jurassic The quality of the fossil record varies immensely across taxa, geographic regions

  7. A Mesozoic time scale

    Microsoft Academic Search

    Felix M. Gradstein; Frits P. Agterberg; James G. Ogg; Jan Hardenbol; Paul van Veen; Jacques Thierry; Zehui Huang

    1994-01-01

    We present an integrated geomagnetic polarity and stratigraphic time scale for the Triassic, Jurassic, and Cretaceous periods of the Mesozoic Era, with age estimates and uncertainty limits for stage boundaries. The time scale uses a suite of 324 radiometric dates, including high-resolution Ar-40\\/Ar-39 age estimates. This framework involves the observed ties between (1) radiometric dates, biozones, and stage boundaries, and

  8. High precision time calibration of the Permian-Triassic boundary mass extinction event in a deep marine context

    NASA Astrophysics Data System (ADS)

    Baresel, Björn; Bucher, Hugo; Brosse, Morgane; Bagherpour, Borhan; Schaltegger, Urs

    2015-04-01

    To construct a revised and high resolution calibrated time scale for the Permian-Triassic boundary (PTB) we use (1) high-precision U-Pb zircon age determinations of a unique succession of volcanic ash layers interbedded with deep water fossiliferous sediments in the Nanpanjiang Basin (South China) combined with (2) accurate quantitative biochronology based on ammonoids, conodonts, radiolarians, and foraminifera and (3) tracers of marine bioproductivity (carbon isotopes) across the PTB. The unprecedented precision of the single grain chemical abrasion isotope-dilution thermal ionization mass spectrometry (CA-ID-TIMS) dating technique at sub-per mil level (radio-isotopic calibration of the PTB at the <100 ka level) now allows calibrating magmatic and biological timescales at resolution adequate for both groups of processes. Using these alignments allows (1) positioning the PTB in different depositional setting and (2) solving the age contradictions generated by the misleading use of the first occurrence (FO) of the conodont Hindeodus parvus, whose diachronous first occurrences are arbitrarily used for placing the base of the Triassic. This new age framework provides the basis for a combined calibration of chemostratigraphic records with high-resolution biochronozones of the Late Permian and Early Triassic. Here, we present new single grain U-Pb zircon data of volcanic ash layers from two deep marine sections (Dongpan and Penglaitan) revealing stratigraphic consistent dates over several volcanic ash layers bracketing the PTB. These analyses define weighted mean 206Pb/238U ages of 251.956±0.033 Ma (Dongpan) and 252.062±0.043 Ma (Penglaitan) for the last Permian ash bed. By calibration with detailed litho- and biostratigraphy new U-Pb ages of 251.953±0.038 Ma (Dongpan) and 251.907±0.033 Ma (Penglaitan) are established for the onset of the Triassic.

  9. Isoarborinol through geological times: Evidence for its presence in the Permian and Triassic

    Microsoft Academic Search

    V. Hauke; P. Adam; J.-M. Trendel; P. Albrecht; L. Schwark; M. Vliex; H. Hagemann; W. Püttmann

    1995-01-01

    Optical rotation measurements and HPLC chiral separations using a ?-cyclodextrin phase, performed on aromatic hydrocarbons isolated from diverse geological sources, and belonging to the arborane or fernane triterpenoid series, have shown that isoarborinol, one of the possible biological precursors, was abundantly present at the time of deposition of Permian and Triassic sediments. This fact considerably reinforces the hypothesis that arborane

  10. Timing of the Early Triassic carbon cycle perturbations inferred from new U Pb ages and ammonoid biochronozones

    NASA Astrophysics Data System (ADS)

    Galfetti, Thomas; Bucher, Hugo; Ovtcharova, Maria; Schaltegger, Urs; Brayard, Arnaud; Brühwiler, Thomas; Goudemand, Nicolas; Weissert, Helmut; Hochuli, Peter A.; Cordey, Fabrice; Guodun, Kuang

    2007-06-01

    Based on analyses of single, thermally annealed and chemically abraded zircons, a new high-precision U-Pb age of 251.22 ± 0.20 Ma is established for a volcanic ash layer within the " Kashmirites densistriatus beds" of early Smithian age (Early Triassic) from the Luolou Formation (northwestern Guangxi, South China). This new date, together with recalculated uncertainties of previous U-Pb ages from the same section [M. Ovtcharova, H. Bucher, U. Schaltegger, T. Galfetti, A. Brayard, J. Guex. New Early to Middle Triassic U-Pb ages from South China: calibration with ammonoid biochronozones and implications for the timing of the Triassic biotic recovery. Earth Planet. Sci. Lett. 243 (2006) 463-475.] allows constraining the time framework of the Early Triassic and leads to an estimated duration of (i) ca. 0.7 ± 0.6 My for the Smithian and (ii) a maximal duration of ca. 1.4 ± 0.4 My for the Griesbachian-Dienerian time interval. The new U-Pb age considerably reduces the absolute age gap comprised between the Permian-Triassic boundary and the Spathian (late Early Triassic). The new age framework provides the basis for the calibration of a new carbonate carbon isotope and ammonoid records of the Early Triassic Luolou Fm., which in turn are of high significance for global correlations and for carbon cycle modeling. This calibration indicates that the most significant and fastest Early Triassic carbon isotope perturbations occur between the earliest Smithian and the early Spathian, thus spanning a time interval of about 1 My. Whatever caused these carbon cycle shifts of high intensity and short duration, there is evidence for connections between these fluctuations, the pulsate recovery of ammonoids and conodonts as well as climate changes.

  11. Lower Triassic sequence stratigraphy of the western part of the Germanic Basin (west of Black Forest): Fluvial system evolution through time and space

    Microsoft Academic Search

    Sylvie Bourquin; Samuel Peron; Marc Durand

    2006-01-01

    The aim of this paper is to analyse the fluvial evolution of the Lower Triassic in the western part of the Germanic Basin through time and space, as well as the impact of the geodynamic and climatic setting on the preservation of fluvial deposits. The Lower Triassic crops out only in the Vosges Massif and the Black Forest, so well-log

  12. Permian and Triassic paleomagnetism of the southwestern Tien Shan: timing and mode of tectonic rotations

    Microsoft Academic Search

    Mikhail L. Bazhenov; Annick Chauvin; Marc Audibert; N. M. Levashova

    1993-01-01

    Volcanic rocks of the Lower Permian Luchob Formation and sedimentary rocks of the presumed Upper Permian Hanaka and Middle-Upper Triassic Madighen formations were studied in three localities in the southwestern Tien Shan. Primary magnetizations were isolated in Lower Permian and Triassic rocks, whereas the remanence of reversed polarity in the Hanaka Formation acquired during the Kiaman superchron may be slightly

  13. Recognising ocean acidification in deep time: An evaluation of the evidence for acidification across the Triassic-Jurassic boundary

    NASA Astrophysics Data System (ADS)

    Greene, Sarah E.; Martindale, Rowan C.; Ritterbush, Kathleen A.; Bottjer, David J.; Corsetti, Frank A.; Berelson, William M.

    2012-06-01

    While demonstrating ocean acidification in the modern is relatively straightforward (measure increase in atmospheric CO2 and corresponding ocean chemistry change), identifying palaeo-ocean acidification is problematic. The crux of this problem is that the rock record is a constructive archive while ocean acidification is essentially a destructive (and/or inhibitory) phenomenon. This is exacerbated in deep time without the benefit of a deep ocean record. Here, we discuss the feasibility of, and potential criteria for, identifying an acidification event in deep time. Furthermore, we investigate the evidence for ocean acidification during the Triassic-Jurassic (T-J) boundary interval, an excellent test case because 1) it occurs in deep time, beyond the reach of deep sea drilling coverage; 2) a potential trigger for acidification is known; and 3) it is associated with one of the 'Big Five' mass extinctions which disproportionately affected modern-style invertebrates. Three main criteria suggest that acidification may have occurred across the T-J transition. 1) The eruption of the Central Atlantic Magmatic Province (CAMP) and the associated massive and rapid release of CO2 coincident with the end-Triassic mass extinction provide a suitable trigger for an acidification event (full carbonate undersaturation in the surface ocean is possible but improbable). 2) Tentative evidence for a global paucity of carbonate across the end-Triassic mass extinction versus the adjacent stratigraphy is consistent with a predicted sedimentary response to acidification. 3) The end-Triassic mass extinction was particularly selective against acid-sensitive organisms (more so than perhaps any other extinction event) and temporarily eliminated coral reefs. Therefore multiple lines of evidence are consistent with a T-J ocean acidification event within our current resolution to recognise such events in deep time. The conclusion that the end-Triassic extinction was influenced by acidification implies that short-term acidification perturbations may have long-term effects on ecosystems, a repercussion that has previously not been established. Although anthropogenic emissions are more rapid than any event in the geologic record, events such as the T-J can serve as partial analogues for the present anthropogenic carbon release. Since the T-J was such a pronounced crisis for both modern-style marine invertebrates and scleractinian reefs, it is of particular interest in terms of informing projections about the effects of modern ocean acidification.

  14. Occupational Cohort Time Scales

    PubMed Central

    Roth, H. Daniel

    2015-01-01

    Purpose: This study explores how highly correlated time variables (occupational cohort time scales) contribute to confounding and ambiguity of interpretation. Methods: Occupational cohort time scales were identified and organized through simple equations of three time scales (relational triads) and the connections between these triads (time scale web). The behavior of the time scales was examined when constraints were imposed on variable ranges and interrelationships. Results: Constraints on a time scale in a triad create high correlations between the other two time scales. These correlations combine with the connections between relational triads to produce association paths. High correlation between time scales leads to ambiguity of interpretation. Conclusions: Understanding the properties of occupational cohort time scales, their relational triads, and the time scale web is helpful in understanding the origins of otherwise obscure confounding bias and ambiguity of interpretation. PMID:25647318

  15. Timing of the Permian-Triassic biotic crisis: implications from new zircon U/Pb age data (and their limitations)

    NASA Astrophysics Data System (ADS)

    Mundil, Roland; Metcalfe, Ian; Ludwig, Kenneth R.; Renne, Paul R.; Oberli, Felix; Nicoll, Robert S.

    2001-04-01

    The most profound biotic crisis in the Earth's history, causing the near extinction of both terrestrial and marine life, occurred at the end of the Permian period about 253 Myr ago and marks the Paleozoic-Mesozoic era boundary. The cause of this event is still a matter of vigorous debate, with both brief and catastrophic as well as gradual mechanisms having been proposed. Similar to a recent landmark study, this study uses the U-Pb method on zircons from the uppermost Permian/lowermost Triassic ash fall deposits at Meishan (Zhejiang Province, SE China) in order to examine time and rate constraints for these events. The results of both this study and previous work show that for these ash layers, the effects of Pb loss are combined with varying amounts and sources of inheritance, resulting in an age scatter which prohibits the extraction of a statistically robust age in many cases. Though the effects of Pb loss on the zircons analyzed in this study were reduced by leaching the grains in hydrofluoric acid (as opposed to commonly applied air abrasion) prior to analysis, the presence within a single ash layer of multiple generations of older xenocrysts (in many cases only slightly older than the depositional age) has made quantitative interpretation even more difficult. When these combined phenomena bias individual zircon ages by less than a percent, they are extremely difficult to deconvolute, and, if multi-grain analyses are used, can become impossible to recognize (because of the resulting age averaging). Monte Carlo simulations using actual measurements of individual zircon crystals show that age excursions due to Pb loss and xenocrystic contamination for the Meishan bentonites are easily homogenized to the point of undetectability when replicate analyses of multi-grain zircon samples are compared. Thus this study uses only high-precision analyses of single crystals, whether from our work or that of previous studies. Three main conclusions have emerged. First, our data require a significant increase in the age of the Permian-Triassic boundary by more than 2 myr compared to the previous study, which shifts the age to a value older than 253 Ma. Second, neither our data nor those from previous work can confirm or negate the possibility of a very abrupt biotic crisis. Third, even large suites of very high-quality, single-zircon U-Pb analyses for these tuffs cannot, in most cases, yield objective, reliable, and robust dates with accuracies at the sub-myr level - though the temptation to perform arbitrary selection of subsets of the analyses for that purpose is almost irresistible. The last conclusion is not an indictment of zircon U/Pb dating in general (other rocks and other zircon populations can - and do - behave very differently), and further technical advances will likely improve our ability to prepare grains or sub-grains of adequately enhanced quality for analysis. Consequently, the results of the present study strongly suggest that for problems requiring time-scale accuracy, inferences from zircon U-Pb dating must be based on sufficiently large suites of single-crystal or crystal domain, high-precision analyses (<1% error) that are realistically interpreted.

  16. Large-scale diabase intrusion in the Durham Triassic Basin of North Carolina: geophysics and geochemistry

    SciTech Connect

    Bolich, R.E.; Bevis, M.G.; Won, I.J.; Fodor, R.V.

    1985-01-01

    Gravity and magnetic data obtained from the Durham Triassic Basin of North Carolina reveal pronounced positive gravity and magnetic anomalies of 10 milligals and 300 gammas, respectively, along the western border of the basin. In the vicinity of these anomalies, diabase outcrops, some with chilled margins and others with flow features, occur sporadically, but have a combined area of about 100 sq. km. Two-dimensional modeling of the gravity data indicates that the diabase body accounts for the gravity anomaly as a semi-continuous subsurface intrusion. The intrusive body is greater than 250 m thick near the western border of the basin, but thins to about 100 m near the center of the basin. Geochemical data for samples recovered from 4 air-drill sites at one diabase outcrop in Butner, North Carolina yield high MgO concentrations, and low FeO, K2O, and TiO2. The geophysical and geochemical data are consistent with an uncontaminated basaltic magma ascending along a major fissure or fissures and into the basin. In the basin, the diabase encountered unlithified sediments, resulting in both intrusive and extrusive forms. Although similar chemical compositions for Mesozoic North American dikes have been reported, this is the first indication of an intrusive body of such a large extent and primitive chemical composition.

  17. Geological Time Scale

    NSDL National Science Digital Library

    This document describes how geologic time is approached in discussions of geologic topics. The uses of relative time and absolute time are compared, and a geologic time scale is provided to represent both concepts. References are provided.

  18. GSA Geologic Time Scale

    NSDL National Science Digital Library

    1999-01-01

    This Geological Society of America (GSA) site contains a detailed geologic time scale as an educational resource. It may be downloaded to a larger size, and includes all Eras, Eons, Periods, Epochs and ages as well as magnetic polarity information.

  19. Interactive Geological Time Scale

    NSDL National Science Digital Library

    This time scale allows students to select multiple time periods from a list and view them on a highlighted display. It shows the relationship between eon, era, period, sub-period, and epoch and also includes the date in mega-annum (Ma) or millions of years before present. The scale reflects the changes in the Cenozoic Era (Tertiary and Quaternary have been eliminated and the Neogene modified) in the most recent International Stratigraphic Charts.

  20. A Geologic Time Scale 2004

    Microsoft Academic Search

    Felix M. Gradstein; James G. Ogg; Alan G. Smith

    2005-01-01

    A successor to A Geologic Time Scale 1989 (Cambridge, 1990), this volume introduces the theory and methodology behind the construction of the new time scale, before presenting the scale itself in extensive detail. An international team of over forty stratigraphic experts develops the most up-to-date international stratigraphic framework for the Precambrian and Phanerozoic eras. A large wallchart summarizing the time

  1. Triassic and Jurassic-Cretaceous deposits in the Western Chukotka: geodynamic implications, provenance studies and deformation

    NASA Astrophysics Data System (ADS)

    Tuchkova, M.

    2012-04-01

    Studied region is situated in western Chukotka, in Northeast Russia. We examine the part of Chukotka microplate, the key element in the evolution of the Amerasian basin. The Triassic of Chukotka is represented by up to 5 km of deposits. Triassic terrigeneous deposits consist of three different complexes: Lower-Middle Triassic, Upper Triassic Carnian, and Norian. All the complexes are represented by rhythmic intercalation of sandstones, siltstones and mudstones. Clastic material was carried by large rivers, possessing large reservoir on neighbouring continent. Progradation of delta system in deeper regions is observed. During the Triassic, sedimentation was represented by continental slope progradation. Petrographic study of mineral composition has established the sandstones as graywackes and lithic arenites, according to Pettijohn classification (1981). Sandstones with clasts of rock fragments of lower metamorphic grade rocks dominate at the base of Triassic deposits, sandstones with fragments of higher grade metamorphic rocks dominate in the Later Triassic deposits. This different shows that the Triassic represents an unroofing sequence sours of erosional processes that produced the clastic material eroded more deeply buried rocks through time. Detrital zircons from Triassic sedimentary rocks were collected for constain its paleogeographic links to source terranes. Zircons populations from these three samples are very similar, and youngest zircon ages show peaks at 236-255 Ma. Besides, we are dating the 9 samples for K-Ar and Rb-Sr methods. Data are similar and show 200-204 Ma, and we suppose that this isotopic data indicate the age of first stage of deformation in Chukotka's basin. The Jurassic-Cretaceous of Chukotka is represented by up to 3 km of deposits. The sedimentary complexes are enriched by organic matter, and fresh clastic materials. Fragments of shales, sometimes laminated or cleaved are their indicator constituents. Sandstones are arkosic. The chemical composition and mineral assemblages are different from Triassic sandstone. Besides, Upper Jurassic sandstones differs from Cretaceous sandstones. Our investigations indicate that Triassic, Upper Jurassic, and Lower Cretaceous sedimentary basins were related to different source provenance. In the paper will discuss the sedimentation, provenances, and geodynamic settings of Triassic and Jurassic-Cretaceous deposits. The studied part of western Chukotka is composed of variably deformed, folded and cleaved rhythmic deposits. Widely distributed and intensively deformed Triassic sequences (Tuchkova et al., 2007) and J-K units both intruded by Aptian-Albian postcollisional plutons and dikes (Katkov et al., 2010). Collisional-related fabric and subsequent granitoids are complicated by small-scale latest normal faults, in particular related to the westernmost segment of South Chukchi (Hope) basin development in Upper Cretaceous (?)-Cenozoic. Intensity of the compressional deformation of Jurassic-Cretaceous rocks is significantly less than in Triassic sequence. Work was supported by RBRR projects 11-05-00787, 11-05-00074, Scientific school # NSh-5177.2012.5, kontrakts No. 04.740.11.0190, and 01/14/20/11.

  2. Absence of extraterrestrial 3 He in PermianTriassic

    E-print Network

    Mukhopadhyay, Sujoy

    Absence of extraterrestrial 3 He in Permian­Triassic age sedimentary rocks K.A. Farley a,*, P. Ward the Permian­Triassic boundary at Opal Creek, Canada, to determine whether high extraterrestrial helium concentrations are associated with a possible extinction- inducing impact event at this time. No extraterrestrial

  3. Geologic time scale bookmark

    USGS Publications Warehouse

    U.S. Geological Survey

    2012-01-01

    This bookmark, designed for use with U.S. Geological Survey activities at the 2nd USA Science and Engineering Festival (April 26–29, 2012), is adapted from the more detailed Fact Sheet 2010–3059 "Divisions of Geologic Time." The information that it presents is widely sought by educators and students.

  4. Triassic-Jurassic marine anoxia in response to massive carbon release from CAMP?

    NASA Astrophysics Data System (ADS)

    Ruhl, M.; Bjerrum, C. J.; Canfield, D. E.; Frei, R.

    2012-04-01

    The end-Triassic mass extinction [~201.3 Ma], marked by marine and terrestrial ecosystem collapse and global marine biodiversity loss, coincides with the onset of extensive volcanic activity and emplacement of the Central Atlantic Magmatic Province (CAMP). Massive and rapid greenhouse gas release from surface basalts, subsurface organic rich strata and ocean-floor clathrate-hydrates had a profound impact on the global exogenic carbon cycle and it dramatically increased atmospheric pCO2 values. Although Permian-Triassic [~252 Ma] and early Toarcian [~183 Ma] volcanic carbon release is thought to have initiated global ocean anoxic events, ocean redox changes at the end-Triassic mass extinction are poorly constrained. Marine anoxia is only suggested by organic-rich, finely laminated sediment deposition in marginal marine basins. We studied the biostratigraphically well-constrained Triassic-Jurassic marine sedimentary record from St. Audrie's Bay (UK), which is astronomically calibrated to the continental geomagnetic polarity time-scale (GPTS) of the continental Newark basin. This marine geological archive is marked by precession paced black-shale deposition, similar to Neogene Mediterranean sapropels. We studied redox-sensitive trace element concentrations (e.g. Mo, U, V, Cu, Ni), iron-speciation (FeHR/FeT, FePY/FeHR) and ?34S-pyrite through the end-Triassic mass extinction and subsequent 3 million years of the lower Jurassic. We observe direct stratigraphic correlation between CAMP flood basalt emplacement, strong atmospheric pCO2 increase and development of marine anoxia. This now allows evaluation of mechanistic relations between massive greenhouse gas emissions initiated by CAMP volcanism, subsequent environmental change and upper Triassic and lower Jurassic biotic response.

  5. Triassic terrigeneous deposits of Western Chukotka: sedimentation, mineral composition, deformations (NE Russia)

    NASA Astrophysics Data System (ADS)

    Tuchkova, M. I.; Bondarenko, G. Y.; Miller, E. L.; Katkov, S. M.

    2004-12-01

    Chukotka's Triassic terrigeneous deposits form three different complexes: Lower-Middle Triassic complex, Upper Triassic Karnian complex and Upper Triassic Norian complex. The studied part of western Chukotka is composed of variably deformed, folded and cleaved rhythmic deposits. All the complexes are represented by rhythmic intercalation of sandstones, siltstones and mudstones. Unfortunately, macrofaunas are not numerous in the Triassic deposits, and in some cases deposits are dated by analogy or comparison to the units dated with macrofaunas. Triassic deposits are composed of hemipelagic sediments, low-density flows, high-density flows, and shelf facies associations. Relationships between the facies were reconstructed with structural researches and data. During the Triassic, sedimentation was represented by continental slope progradation. Petrographic study of mineral composition has established the sandstones as graywackes (classification diagram by Shutov, 1972). Although Triassic sandstones are similar in outcrops and classification, the enclosed rocks fragment grains are different. Rock fragment grains in sandstones are composed of diverse lithologies, and we chart the evolution of their composition from the Lower to the Upper Triassic. Sandstones with (clasts) rock fragments of lower metamorphic grade rocks dominate at the base of Triassic deposits, sandstones with fragments of higher grade metamorphic rocks dominate in the Later Triassic deposits. This different show us that the Triassic represents an unroofing sequence where(sours of) erosional processes that produced the clastic material eroded more deeply buried rocks through time. Supported by RFFI (grants 02-05-64217, 03-05-64915).

  6. Triassic palaeogeography of Tunisia

    Microsoft Academic Search

    F Kamoun; B Peybernès; R Ciszak; S Calzada

    2001-01-01

    A stratigraphic, palaeogeographic and palinspastic synthesis of the Triassic successions in Tunisia is herein documented from a SSE–NNN oriented profile (Saharan Platform, Gulf of Gabes offshore, Tunisian Atlas, Tellian Units) across the northern boundary of the Gondwana Plate and the future South-Tethyan Margin. It is principally based on a reinvestigation of old data and on recent results, particularly related to

  7. Deep Time: The Geologic Time Scale

    NSDL National Science Digital Library

    2007-01-01

    This page examines the issues involved in teaching students about the geologic time scale. There are suggestions for tackling troublesome issues in class as well as activities that can be used to clarify how geoscientists look at deep time. Five main concepts with which students struggle when thinking about Deep Time are addressed here: imagining or comprehending big numbers; the difference between relative and numerical age; the concept of "timescales"; the ways we know about the age of the Earth and other materials; and resolving perceived issues with religious beliefs.

  8. Pair plasma relaxation time scales.

    PubMed

    Aksenov, A G; Ruffini, R; Vereshchagin, G V

    2010-04-01

    By numerically solving the relativistic Boltzmann equations, we compute the time scale for relaxation to thermal equilibrium for an optically thick electron-positron plasma with baryon loading. We focus on the time scales of electromagnetic interactions. The collisional integrals are obtained directly from the corresponding QED matrix elements. Thermalization time scales are computed for a wide range of values of both the total-energy density (over 10 orders of magnitude) and of the baryonic loading parameter (over 6 orders of magnitude). This also allows us to study such interesting limiting cases as the almost purely electron-positron plasma or electron-proton plasma as well as intermediate cases. These results appear to be important both for laboratory experiments aimed at generating optically thick pair plasmas as well as for astrophysical models in which electron-positron pair plasmas play a relevant role. PMID:20481841

  9. Developing an IGS time scale.

    PubMed

    Senior, Ken; Koppang, Paul; Ray, Jim

    2003-06-01

    Currently, the International GPS Service (IGS) provides a set of clock products for both satellites and tracking receivers, tabulated at 5-min intervals. These products allow users to determine consistent coordinates and clock values for an isolated GPS receiver with an internal accuracy at the few-cm level. However, because the underlying time scale for the IGS combined clocks is based on a linear alignment to broadcast GPS Time for each day separately, the day-to-day stability of this reference is poor. We show the results of a new filter package written to automate the production of an integrated IGS frequency scale based on a dynamically weighted ensemble of the included frequency standards. The new scale is loosely steered to GPS Time. PMID:12839170

  10. The Concise Geologic Time Scale

    Microsoft Academic Search

    James G. Ogg; Gabi Ogg; Felix M. Gradstein

    2008-01-01

    This concise handbook presents a summary of Earth's history over the past 4.5 billion years as well as a brief overview of contemporaneous events on the Moon, Mars and Venus. The authors have been at the forefront of chronostratigraphic research and initiatives to create an international geologic time scale for many years, and the charts in this book present the

  11. Time Scales in Particulate Systems

    NASA Astrophysics Data System (ADS)

    Zhang, Duan

    2013-06-01

    While there are many interests of studying interactions of individual particles, macroscopic collective behavior of particles are our main interest in many practical applications. In this talk, I will give a brief overview of the multiscale methods connecting the physics at individual particles to macroscopic quantities and averaged equations. The emphasis will be on dense dissipative particulate systems, such as powders. Unlike conservative particle systems, such as molecular systems, in a dissipative particle system the concept of thermodynamic equilibrium is not very useful unless in very special cases, because the only true thermodynamically equilibrium state in these systems is the state in which nothing moves. Other than idealized simple systems, mesoscale structures are common and important in many practical systems, especially in dissipative systems. Spatial correlations of these mesoscale structures, such as force chains in dense granular system, particle clusters and streamers in fluidized beds have received some recent attentions, partly because they can be visualized. This talk will emphasize the effects of time correlations related to the mesoscale structures. To consider time correlations and history information of the system, I will introduce the mathematical foundation of the Liouville equation, its applicability and limitations. I will derive the generalized Liouville equations for particulate systems with and without interstitial fluids, and then use them to study averaged transport equations and related closures. Interactions among the time scale of particle interactions, the time scale of the mesocale structures, and the time scale of the physical problem as represented by strain rate will be discussed. The effect of these interactions on the closure relations will be illustrated. I will also discuss possible numerical methods of solving the averaged equations, and multiscale numerical algorithms bridging the particle level calculations to continuum level calculations. While there are many interests of studying interactions of individual particles, macroscopic collective behavior of particles are our main interest in many practical applications. In this talk, I will give a brief overview of the multiscale methods connecting the physics at individual particles to macroscopic quantities and averaged equations. The emphasis will be on dense dissipative particulate systems, such as powders. Unlike conservative particle systems, such as molecular systems, in a dissipative particle system the concept of thermodynamic equilibrium is not very useful unless in very special cases, because the only true thermodynamically equilibrium state in these systems is the state in which nothing moves. Other than idealized simple systems, mesoscale structures are common and important in many practical systems, especially in dissipative systems. Spatial correlations of these mesoscale structures, such as force chains in dense granular system, particle clusters and streamers in fluidized beds have received some recent attentions, partly because they can be visualized. This talk will emphasize the effects of time correlations related to the mesoscale structures. To consider time correlations and history information of the system, I will introduce the mathematical foundation of the Liouville equation, its applicability and limitations. I will derive the generalized Liouville equations for particulate systems with and without interstitial fluids, and then use them to study averaged transport equations and related closures. Interactions among the time scale of particle interactions, the time scale of the mesocale structures, and the time scale of the physical problem as represented by strain rate will be discussed. The effect of these interactions on the closure relations will be illustrated. I will also discuss possible numerical methods of solving the averaged equations, and multiscale numerical algorithms bridging the particle level calculations to continuum level calculations. This work was sponsored by Stockpile Safety and

  12. Time scales in cognitive neuroscience.

    PubMed

    Papo, David

    2013-01-01

    Cognitive neuroscience boils down to describing the ways in which cognitive function results from brain activity. In turn, brain activity shows complex fluctuations, with structure at many spatio-temporal scales. Exactly how cognitive function inherits the physical dimensions of neural activity, though, is highly non-trivial, and so are generally the corresponding dimensions of cognitive phenomena. As for any physical phenomenon, when studying cognitive function, the first conceptual step should be that of establishing its dimensions. Here, we provide a systematic presentation of the temporal aspects of task-related brain activity, from the smallest scale of the brain imaging technique's resolution, to the observation time of a given experiment, through the characteristic time scales of the process under study. We first review some standard assumptions on the temporal scales of cognitive function. In spite of their general use, these assumptions hold true to a high degree of approximation for many cognitive (viz. fast perceptual) processes, but have their limitations for other ones (e.g., thinking or reasoning). We define in a rigorous way the temporal quantifiers of cognition at all scales, and illustrate how they qualitatively vary as a function of the properties of the cognitive process under study. We propose that each phenomenon should be approached with its own set of theoretical, methodological and analytical tools. In particular, we show that when treating cognitive processes such as thinking or reasoning, complex properties of ongoing brain activity, which can be drastically simplified when considering fast (e.g., perceptual) processes, start playing a major role, and not only characterize the temporal properties of task-related brain activity, but also determine the conditions for proper observation of the phenomena. Finally, some implications on the design of experiments, data analyses, and the choice of recording parameters are discussed. PMID:23626578

  13. Time scales, their users, and leap seconds

    Microsoft Academic Search

    P. Kenneth Seidelmann; John H. Seago

    2011-01-01

    Numerous time scales exist to address specific user requirements. Accurate dynamical time scales (barycentric, geocentric and terrestrial) have been developed based on the theory of relativity. A family of time scales has been developed based on the rotation of the Earth that includes Universal Time (specifically UT1), which serves as the traditional astronomical basis of civil time. International Atomic Time

  14. Time scales in spectator fragmentation

    NASA Astrophysics Data System (ADS)

    Schwarz, C.; Fritz, S.; Bassini, R.; Begemann-Blaich, M.; Gaff-Ejakov, S. J.; Gourio, D.; Groß, C.; Immé, G.; Iori, I.; Kleinevoß, U.; Kunde, G. J.; Kunze, W. D.; Lynen, U.; Maddalena, V.; Mahi, M.; Möhlenkamp, T.; Moroni, A.; Müller, W. F. J.; Nociforo, G.; Ocker, B.; Ohed, T.; Pertruzzelli, F.; Pochodzalla, J.; Raciti, G.; Riccobene, G.; Romano, F. P.; Saija, A.; Schnittker, M.; Schüttauf, A.; Seidel, W.; Serfling, V.; Sfienti, C.; Trautmann, W.; Trzcinski, A.; Verde, G.; Wörner, A.; Xi, Hongfei; Zwieglinski, B.

    2001-01-01

    Proton-proton correlations and correlations of p-alpha, d-alpha, and t-alpha from spectator decays following Au + Au collisions at 1000 AMeV have been measured with an highly efficient detector hodoscope. The constructed correlation functions indicate a moderate expansion and low breakup densities similar to assumptions made in statistical multifragmentation models. In agreement with a volume breakup rather short time scales were deduced employing directional cuts in proton-proton correlations. PACS numbers: 25.70.Pq, 21.65.+f, 25.70.Mn

  15. Improving the Geologic Time Scale (Jean Baptiste Lamarck Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Gradstein, Felix M.

    2010-05-01

    The Geologic Time Scale (GTS) provides the framework for the physical, chemical and biological processes on Earth. The time scale is the tool "par excellence" of the geological trade, and insight in its construction, strength, and limitations enhances its function and its utility. Earth scientists should understand how time scales are constructed and its myriad of physical and abstract data are calibrated, rather than merely using ages plucked from a convenient chart or card. Calibration to linear time of the succession of events recorded in the rocks on Earth has three components: (1) the standard stratigraphic divisions and their correlation in the global rock record, (2) the means of measuring linear time or elapsed durations from the rock record, and (3) the methods of effectively joining the two scales, the stratigraphic one and the linear one. Under the auspices of the International Commission on Stratigraphy (ICS), the international stratigraphic divisions and their correlative events are now largely standardized, especially using the GSSP (Global Stratigraphic Section and Point) concept. The means of measuring linear time or elapsed durations from the rock record are objectives in the EARTH TIME and GTS NEXT projects, that also are educating a new generation of GTS dedicated scientists. The U/Pb, Ar/Ar and orbital tuning methods are intercalibrated, and external error analysis improved. Existing Ar/Ar ages become almost 0.5% older, and U/Pb ages stratigraphically more realistic. The new Os/Re method has potential for directly dating more GSSP's and its correlative events. Such may reduce scaling uncertainty between the sedimentary levels of an age date and that of a stage boundary. Since 1981, six successive Phanerozoic GTS have been published, each new one achieving higher resolution and more users. The next GTS is scheduled for 2011/2012, with over 50 specialists taking part. New chapters include an expanded planetary time scale, sequence stratigraphy, Osmium, Carbon and Oxygen stratigraphy, the Cryogenian period, history of the plants, hominid prehistory, and last but not least the Anthropocene. The Cambrian Period is radically improved with 10 standard stages and detailed trilobite biochronology. Ordovician now has a stable international stages and graptolites scale. The integration of a refined 100 and 400 ka sedimentary cycles scale and a truly high-resolution U/Pb ages scale for the Mississippian is a major step towards the global Carboniferous GTS. The Devonian GTS leaves to be desired with lack of firm definitions for its upper boundary, and the long Emsian stage; it also lacks age dates. Its stages scaling is disputed. The Rhaetian and Norian stages in the Triassic and the Berriasian stage in the Cretaceous urgently require lower boundary definitions, and also boundary age dates. The single ~400 ka eccentricity component is very stable and can extend orbital tuning from the Cenozoic well into the Mesozoic portion of the GTS. Jurassic and Cretaceous now have long orbitally tuned segments. A completely astronomical-tuned Geological Time Scale (AGTS) for the Cenozoic is within reach showing unprecedented accuracy, precision and resolution. Burdigalian in the Miocene, and Lutetian, Bartonian and Priabonian stages in the Eocene still require formal definition. The K/T boundary will become about 0.5 ± 0.1 Ma older. After 25 years of research and authorship in the GTS it behoves me to especially thank my colleagues James Ogg, Frits Agterberg, John McArthur and Roger Cooper for longstanding collaboration. As a final note I urge construction of more regional time scales(like developed ‘down under') calibrated to the standard global GTS, to scale regional rock units.

  16. Multiple time scale analysis of runaway phenomena

    Microsoft Academic Search

    Lucio Demeio

    1998-01-01

    The analysis of runaway phenomena with the use of the Boltzmann equation shows that the time evolution of the distribution function and of the other quantities of interest, for example the average velocity, occurs on two time scales: the short time scale of the collisional equilibrium and the long time scale of the runaway flux. Under suitable conditions on the

  17. Advances in time-scale algorithms

    NASA Technical Reports Server (NTRS)

    Stein, S. R.

    1993-01-01

    The term clock is usually used to refer to a device that counts a nearly periodic signal. A group of clocks, called an ensemble, is often used for time keeping in mission critical applications that cannot tolerate loss of time due to the failure of a single clock. The time generated by the ensemble of clocks is called a time scale. The question arises how to combine the times of the individual clocks to form the time scale. One might naively be tempted to suggest the expedient of averaging the times of the individual clocks, but a simple thought experiment demonstrates the inadequacy of this approach. Suppose a time scale is composed of two noiseless clocks having equal and opposite frequencies. The mean time scale has zero frequency. However if either clock fails, the time-scale frequency immediately changes to the frequency of the remaining clock. This performance is generally unacceptable and simple mean time scales are not used. First, previous time-scale developments are reviewed and then some new methods that result in enhanced performance are presented. The historical perspective is based upon several time scales: the AT1 and TA time scales of the National Institute of Standards and Technology (NIST), the A.1(MEAN) time scale of the US Naval observatory (USNO), the TAI time scale of the Bureau International des Poids et Measures (BIPM), and the KAS-1 time scale of the Naval Research laboratory (NRL). The new method was incorporated in the KAS-2 time scale recently developed by Timing Solutions Corporation. The goal is to present time-scale concepts in a nonmathematical form with as few equations as possible. Many other papers and texts discuss the details of the optimal estimation techniques that may be used to implement these concepts.

  18. The Paleomagnetic record of Uppermost Permian, Lower Triassic rocks from the South China Block

    NASA Astrophysics Data System (ADS)

    Enkin, R. J.; Courtillot, V.; Leloup, Ph.; Yang, Z.; Xing, L.; Zhang, J.; Zhuang, Z.

    1992-11-01

    Paleomagnetic samples were collected from Uppermost Permian to Middle Triassic limestones from two localities in the Sichuan Basin in order to better constrain the paleography of the blocks now comprising China. Corresponding remanences found in other studies of the Permo-Triassic rocks from the Sichuan Basin are reviewed, and it is shown that the component is probably characteristic of the Lower Triassic. The difference between the Emeishan Basalts and the Sichuan Basin poles is interpreted to be the result of motion of the whole South China Block around the time of the Permo-Triassic boundary rather than that of strain within the block.

  19. Gondwana's climate history inferred from the palynological record of South Africa's coal deposits: the Early Triassic wet intermezzo

    NASA Astrophysics Data System (ADS)

    Götz, Annette E.

    2013-04-01

    Permian-Triassic coals of the South African Karoo Basin play a central role in the study and interpretation of Gondwana's climate history and related vegetational changes in time and space. The palynological record of the coal-bearing formations reveals major phases of climate amelioration succeeding the Permo-Carboniferous Gondwana glaciations. Subsequent to the melting of the Dwyka ice, cold to cool-temperate climate conditions prevailed during the Early Permian and a continuous change to hot and dry climate conditions of the Late Permian and Triassic was inferred from sedimentological and palaeontological data so far. The here presented new palynological and geochemical data from the Early Triassic Molteno coal (Stormberg Group) point to a short-term switch from dry to wet climate conditions. To date, this wet intermezzo of Gondwana's early Mesozoic climate history has been overlooked in the Molteno coal of the Karoo Basin. The spore/pollen ratios, used as a proxy for humidity changes, indicate a significant climatic change corresponding to a prominent C-isotope excursion. Ongoing studies will provide a detailed palynological inventory of the Early Triassic coal deposits on an intra-Gondwanic scale, contributing to the interpretation of early Mesozoic palaeoclimates.

  20. Time scales, their users, and leap seconds

    NASA Astrophysics Data System (ADS)

    Seidelmann, P. Kenneth; Seago, John H.

    2011-08-01

    Numerous time scales exist to address specific user requirements. Accurate dynamical time scales (barycentric, geocentric and terrestrial) have been developed based on the theory of relativity. A family of time scales has been developed based on the rotation of the Earth that includes Universal Time (specifically UT1), which serves as the traditional astronomical basis of civil time. International Atomic Time (TAI) is also maintained as a fundamental time scale based on the output of atomic frequency standards. Coordinated Universal Time (UTC) is an atomic scale for worldwide civil timekeeping, referenced to TAI, but with epoch adjustments via so-called leap seconds to remain within one second of UT1. A review of the development of the time scales, the status of the leap-second issue, and user considerations and perspectives are discussed. A description of some more recent applications for time usage is included.

  1. Modeling orbital changes on tectonic time scales

    NASA Technical Reports Server (NTRS)

    Crowley, Thomas J.

    1992-01-01

    Geologic time series indicate significant 100 ka and 400 ka pre-Pleistocene climate fluctuations, prior to the time of such fluctuations in Pleistocene ice sheets. The origin of these fluctuations must therefore depend on phenomena other than the ice sheets. In a previous set of experiments, we tested the sensitivity of an energy balance model to orbital insolation forcing, specifically focusing on the filtering effect of the Earth's geography. We found that in equatorial areas, the twice-yearly passage of the sun across the equator interacts with the precession index to generate 100 ka and 400 ka power in our modeled time series. The effect is proportional to the magnitude of land in equatorial regions. We suggest that such changes may reflect monsoonal variations in the real climate system, and the subsequent wind and weathering changes may transfer some of this signal to the marine record. A comparison with observed fluctuations of Triassic lake levels is quite favorable. A number of problems remain to be studied or clarified: (1) the EBM experiments need to be followed up by a limited number of GCM experiments; (2) the sensitivity to secular changes in orbital forcing needs to be examined; (3) the possible modifying role of sedimentary processes on geologic time series warrants considerably more study; (4) the effect of tectonic changes on Earth's rotation rate needs to be studied; and (5) astronomers need to make explicit which of their predictions are robust and geologists and astronomers have to agree on which of the predictions are most testable in the geologic record.

  2. Sedimentology, stratigraphy, and micropalaeontology of the Upper Triassic reefal series in Eastern Sulawesi (Indonesia)

    Microsoft Academic Search

    Rossana Martini; Daniel Vachard; Louisette Zaninetti; Simonetta Cirilli; Jean-Jacques Cornée; Bernard Lathuilière; Michel Villeneuve

    1997-01-01

    An Upper Triassic (Upper Norian-Rhaetian) carbonate complex, composed of open marine to reefal deposits, has been investigated for the first time in Eastern Sulawesi. The age is based on the occurrence of benthic foraminifera, and also of the Upper Sevatian to Rhaetian conodont Misikella posthernsteini Kozur and Mock. Palynological assemblages contain Upper Triassic-Lower Jurassic palynomorphs. The scleractinian coral Retiophyllia seranica

  3. `Perfect reconstruction' time-scaling filterbanks

    Microsoft Academic Search

    T. F. Quatieri; T. E. Hanna

    1999-01-01

    A filterbank-based method of time-scale modification is analyzed for elemental signals including clicks, sines, and AM-FM sines. It is shown that with the use of some basic properties of linear systems, as well as FM-to-AM filter transduction, “perfect reconstruction” time-scaling filterbanks can be constructed for these elemental signal classes under certain conditions on the filterbank. Conditions for perfect reconstruction time-scaling

  4. Albertiana 33 Triassic in Chaohu, Anhui Province

    E-print Network

    Tong, Jinnan

    the GSSP of the Permian-Triassic boundary is located. Geologically, Chaohu was situated in the northern mar in the studied Triassic sections the complete sequence from the Upper Permian to Middle Triassic occurs only in Mt. Majiashan, the southern part of the syncline, but the Up- per Permian-Lower Olenekian sequence

  5. Time domain models for multiple time scale linear systems

    Microsoft Academic Search

    R. Silva-Madriz; S. S. Sastry

    1984-01-01

    We study the multiple time scales structure of linear systems of the form x = A0(¿)x + B0(¿)u y = C0(¿)x with a view to obtaining 'approximate' lower order dynamical models valid at different time scales. Our development includes the classical two time-scale case. We use our results to study the robustness of the positive realness of linear systems systems

  6. Paleomagnetic age constrains and magneto-mineralogic implications for the Triassic paleosurface in Europe

    NASA Astrophysics Data System (ADS)

    Franke, Christine; Thiry, Medard; Gomez-Gras, David; Jelenska, Maria; Kadzialko-Hofmokl, Magdalena; Lagroix, France; Parcerisa, David; Spassov, Simo; Szuszkiewicz, Adam; Turniak, Krzysztof

    2010-05-01

    The reconstruction of paleosurfaces represents a unique tool to access the evolution of ancient continents. Paleosurfaces contribute to the study of global changes through paleoweathering features/profiles and record uplift and subsidence of the ancient continents driven by crustal geodynamics and plate tectonics. However, age constraints for basement paleosurfaces are often difficult to obtain since the geological record of ancient land surfaces is usually limited, fragmented by unconformities and scrambled by successive superimposed evolutions, leaving a patchwork of relict landforms and weathering products, discontinuous over time and space. The crystalline basement of European Paleozoic massifs, consisting of igneous and metamorphic rocks, often show Permo-Triassic overprints resulting in underestimated age determinations. These remagnetisations are ubiquitous [e.g. Edel & Schneider, 1995], affecting many emerged Paleozoic rocks in Europe. The rejuvenated age estimations are attributed to an alteration of the primary paleomagnetic signal and carried by secondary hematite [Ricordel et al., 2007; Preeden et al., 2009; Preeden, 2009]. Moreover, published paleomagnetic ages [Ricordel et al., 2007] showed a strong relationship between the remagnetization and the development of pinkish-red crystalline facies associated to the albitized underlying rocks of the Morvan Massif (France). Parcerisa et al. [2009] performed further field and petrographic analyses and proposed that the albitization was linked to the precipitation of secondary haematite. Since hematite forms under oxidising conditions one may deduce that the remagnetization occurring in the Paleozoic crystalline rocks formed during the exposure of these rocks at the Permo-Triassic (paleo)surface. The extent of the altered zone (~200 m in depth) points to a sodium enriched groundwater environment [Thiry et al., 2009]. Demonstrating that the albitized facies are of supergenic origin and bound to the Triassic paleosurface deeply renews the ideas about the evolution of basement areas. The recognition of the Triassic paleosurface on widespread basements in Europe will provide spatio-temporal benchmarks to constrain the ablation of these massifs since the Triassic. This will be a major contribution to the geodynamic modelling of continental evolution of Europe. To deepen our understanding of this paleoalteration phenomenon on a supra-regional scale and to obtain a reasonable distribution of paleomagnetic age determinations, we aim to acquire more tie points for this Permo-Triassic surface, which was preserved in the crystalline basement of Europe throughout the Mesozoic and Cenozoic epochs. We will present results from paleomagnetic investigations as well as magneto-mineralogic analyses of the profiles through albitized granite and porphyry from the Sudetes in SW-Poland and the Catalonian Mountains in NE-Spain, for which preliminary age estimations have been carried out. Further European Paleozoic sample sites are in process. Depending on the depth situation of the sampled facies compared to the weathering profile, the Triassic paleomagnetic ages show dispersion towards rather older ages at the top and younger ages at the bottom of the sequence. This seems to correlate with the results from magneto-mineralogical analyses which show a decreasing hematite concentration with depth. The oldest ages are carried by a single component, identified as single-domain secondary hematite inclusions in the secondary albite crystals. With increasing depth the samples are rather characterized by a two-component signal, still showing (younger) Triassic ages for both components. These were identified as secondary hematite and maghemite. The latter is most probably a product of either low-temperature magnetite oxidation or precipitates during the albitization of the primary rock. These processes are both linked to less oxidising conditions than at the top of the weathering profile. A systematic interpretation of the paleomagnetic ages and the identification of the magnetic carrier assem

  7. Reccurent Early Triassic marine anoxia, impacts of volcanics?

    NASA Astrophysics Data System (ADS)

    Grasby, Stephen; Beauchamp, Benoit; Sanei, Hamed

    2014-05-01

    NW Pangea records a complex history of recurrent development of anoxia through the Permo-Triassic Biotic Crises. The Early Triassic record from the Smithian strato-type in the Sverdrup Basin, as well as for the more open ocean setting of Svalbard, have organic carbon isotope records that closely correspond to major fluctuations in the inorganic carbon records from the Tethys, demonstrating truly global perturbations of the carbon cycle occurred during this time. Geochemical proxies for anoxia are strongly correlated with carbon isotopes, whereby negative shifts in ?13Corg are associated with shifts to more anoxic to euxinic conditions, and positive shifts are related to return to more oxic conditions. Rather than a delayed or prolonged recovery, the Early Triassic is characterized better by a series of aborted biotic recoveries related to shifts back to ocean anoxia, potentially driven by recurrent volcanism.

  8. A reappraisal of the Middle Triassic chirotheriid Chirotherium ibericus Navás, 1906 (Iberian Range NE Spain), with comments on the Triassic tetrapod track biochronology of the Iberian Peninsula

    PubMed Central

    Castanera, Diego; Gasca, José Manuel; Canudo, José Ignacio

    2015-01-01

    Triassic vertebrate tracks are known from the beginning of the 19th century and have a worldwide distribution. Several Triassic track ichnoassemblages and ichnotaxa have a restricted stratigraphic range and are useful in biochronology and biostratigraphy. The record of Triassic tracks in the Iberian Peninsula has gone almost unnoticed although more than 25 localities have been described since 1897. In one of these localities, the naturalist Longinos Navás described the ichnotaxon Chirotherium ibericus in 1906.The vertebrate tracks are in two sandy slabs from the Anisian (Middle Triassic) of the Moncayo massif (Zaragoza, Spain). In a recent revision, new, previously undescribed vertebrate tracks have been identified. The tracks considered to be C. ibericus as well as other tracks with the same morphology from both slabs have been classified as Chirotherium barthii. The rest of the tracks have been assigned to Chirotheriidae indet., Rhynchosauroides isp. and undetermined material. This new identification of C. barthii at the Navás site adds new data to the Iberian record of this ichnotaxon, which is characterized by the small size of the tracks when compared with the main occurrences of this ichnotaxon elsewhere. As at the Navás tracksite, the Anisian C. barthii-Rhynchosauroides ichnoassemblage has been found in other coeval localities in Iberia and worldwide. This ichnoassemblage belongs to the upper Olenekian-lower Anisian interval according to previous biochronological proposals. Analysis of the Triassic Iberian record of tetrapod tracks is uneven in terms of abundance over time. From the earliest Triassic to the latest Lower Triassic the record is very scarce, with Rhynchosauroides being the only known ichnotaxon. Rhynchosauroides covers a wide temporal range and gives poor information for biochronology. The record from the uppermost Lower Triassic to the Middle Triassic is abundant. The highest ichnodiversity has been reported for the Anisian with an assemblage composed of Dicynodontipus, Procolophonichnium, Rhynchosauroides, Rotodactylus, Chirotherium, Isochirotherium, Coelurosaurichnus and Paratrisauropus. The Iberian track record from the Anisian is coherent with the global biochronology proposed for Triassic tetrapod tracks. Nevertheless, the scarcity of track occurrences during the late Olenekian and Ladinian prevents analysis of the corresponding biochrons. Finally, although the Iberian record for the Upper Triassic is not abundant, the presence of Eubrontes, Anchisauripus and probably Brachychirotherium is coherent with the global track biochronology as well. Thus, the Triassic track record in the Iberian Peninsula matches the expected record for this age on the basis of a global biochronological approach, supporting the idea that vertebrate Triassic tracks are a useful tool in biochronology. PMID:26137425

  9. Provenance analysis and tectonic setting of the Triassic clastic deposits in Western Chukotka, Northeast Russia

    NASA Astrophysics Data System (ADS)

    Tuchkova, M. I.; Sokolov, S.; Kravchenko-Berezhnoy, I. R.

    2009-09-01

    The study area is part of the Anyui subterrane of the Chukotka microplate, a key element in the evolution of the Amerasia Basin, located in Western Chukotka, Northeast Russia. The subterrane contains variably deformed, folded and cleaved rhythmic Triassic terrigenous deposits which represent the youngest stage of widespread marine deposition which form three different complexes: Lower-Middle Triassic, Upper Triassic (Carnian) and Upper Triassic (Norian). All of the complexes are represented by rhythmic interbeds of sandstone, siltstone and mudstone. Macrofaunas are not numerous, and in some cases deposits are dated by analogy to, or by their relationship with, other units dated with macrofaunas. The deposits are composed of pelagic sediments, low-density flows, high-density flows, and shelf facies associations suggesting that sedimentation was controlled by deltaic progradation on a continental shelf and subsequent submarine fan sedimentation at the base of the continental slope. Petrographic study of the mineral composition indicates that the sandstones are lithic arenites. Although the Triassic sandstones appear similar in outcrop and by classification, the constituent rock fragments are of diverse lithologies, and change in composition from lower grade metamorphic rocks in the Lower-Middle Triassic to higher grade metamorphic rocks in the Upper Triassic. This change suggests that the Triassic deposits represent an unroofing sequence as the source of the clastic material came from more deeply buried rocks with time.

  10. Metaphor for the geologic time scale

    NSDL National Science Digital Library

    Cara Thompson

    This assignment serves as an introduction to the geologic time scale and to help students visualize the long time intervals between major events in Earth's history. The assignment encourages students to choose a metaphor for geologic time, research major events throughout Earth' history, and calculate how much (cumulative) of their metaphor each time interval represents.

  11. Triassic origin and early radiation of multicellular volvocine algae

    E-print Network

    Triassic origin and early radiation of multicellular volvocine algae Matthew D. Herron1 , Jeremiah-studied ETIs is the origin of multicellularity in the green alga Volvox, a model system for the evolution occurred dozens of times independently, for example in the red algae, brown algae, land plants, animals

  12. Mouse Activity across Time Scales: Fractal Scenarios

    PubMed Central

    Lima, G. Z. dos Santos; Lobão-Soares, B.; do Nascimento, G. C.; França, Arthur S. C.; Muratori, L.; Ribeiro, S.; Corso, G.

    2014-01-01

    In this work we devise a classification of mouse activity patterns based on accelerometer data using Detrended Fluctuation Analysis. We use two characteristic mouse behavioural states as benchmarks in this study: waking in free activity and slow-wave sleep (SWS). In both situations we find roughly the same pattern: for short time intervals we observe high correlation in activity - a typical 1/f complex pattern - while for large time intervals there is anti-correlation. High correlation of short intervals ( to : waking state and to : SWS) is related to highly coordinated muscle activity. In the waking state we associate high correlation both to muscle activity and to mouse stereotyped movements (grooming, waking, etc.). On the other side, the observed anti-correlation over large time scales ( to : waking state and to : SWS) during SWS appears related to a feedback autonomic response. The transition from correlated regime at short scales to an anti-correlated regime at large scales during SWS is given by the respiratory cycle interval, while during the waking state this transition occurs at the time scale corresponding to the duration of the stereotyped mouse movements. Furthermore, we find that the waking state is characterized by longer time scales than SWS and by a softer transition from correlation to anti-correlation. Moreover, this soft transition in the waking state encompass a behavioural time scale window that gives rise to a multifractal pattern. We believe that the observed multifractality in mouse activity is formed by the integration of several stereotyped movements each one with a characteristic time correlation. Finally, we compare scaling properties of body acceleration fluctuation time series during sleep and wake periods for healthy mice. Interestingly, differences between sleep and wake in the scaling exponents are comparable to previous works regarding human heartbeat. Complementarily, the nature of these sleep-wake dynamics could lead to a better understanding of neuroautonomic regulation mechanisms. PMID:25275515

  13. Observing Reality on Different Time Scales

    NASA Astrophysics Data System (ADS)

    Alyushin, Alexey

    2005-10-01

    In the first part of the paper, I examine cases of acceleration of perception and cognition and provide my explanation of the mechanism of the effect. The explanation rests on the conception of neuronal temporal frames, or windows of simultaneity. Frames have different standard durations and yield to stretching and compressing. I suggest it to be the cause of the effect, as well as the ground for differences in perceptive time scales of living beings. In the second part, I apply the conception of temporal frames to model observation in the extended time scales that reach far beyond the temporal perceptive niche of individual living beings. Duration of a frame is taken as the basic parameter setting a particular time scale. By substituting a different frame duration, we set a hypothetical time scale and emulate observing reality in a wider or a narrower angle of embracing events in time. I discuss the status of observer in its relation to objective reality, and examine how reality does change its appearance when observed in different time scales.

  14. A NEW SHRIMP (DECAPODA, DENDROBRANCHIATA, PENAEOIDEA) FROM THE MIDDLE TRIASSIC OF YUNNAN, SOUTHWEST CHINA

    E-print Network

    Benton, Michael

    the type species, Aeger tipularius from the Jurassic Solnhofen Plattenkalk, in having a long, smooth of the marine ecosystem between Eastern and Western Tethys. INTRODUCTION THE TRIASSIC Period was a pivotal time

  15. Time scale synchronization of chaotic oscillators

    E-print Network

    Alexander Hramov; Alexey Koronovskii

    2006-02-25

    This paper presents the result of the investigation of chaotic oscillator synchronization. A new approach for detecting of synchronized behaviour of chaotic oscillators has been proposed. This approach is based on the analysis of different time scales in the time series generated by the coupled chaotic oscillators. This approach has been applied for the coupled Rossler and Lorenz systems.

  16. Time Invariant Scaling in Discrete Fragmentation Models

    E-print Network

    B. G. Giraud; R. Peschanski

    1994-09-13

    Linear rate equations are used to describe the cascading decay of an initial heavy cluster into fragments. We consider moments of arbitrary orders of the mass multiplicity spectrum and derive scaling properties pertaining to their time evolution. We suggest that the mass weighted multiplicity is a suitable observable for the discovery of scaling. Numerical tests validate such properties, even for moderate values of the initial mass (nuclei, percolation clusters, jets of particles etc.). Finite size effects can be simply parametrized.

  17. Reconstructing paleoenvironment in the west-tethyan continental domain at the Late Permian and Early Triassic from sedimentological and palaeobotanical data

    NASA Astrophysics Data System (ADS)

    Bercovici, Antoine; Bourquin, Sylvie; Broutin, Jean; Diez, José B.

    2010-05-01

    The final buildup of Pangea at the end of the Palaeozoic led to the formation of massive landmass unrivaled in later times. On a climatic perspective, the end of the Carboniferous ice age opened into a period of progressive warming, creating vast arid regions on land. The lower Triassic is the culmination of this trend, and represents a period where land vegetation is scarce or non-existent. The following work presents the palaeogeographical evolution of the north-western tethyan terrestrial domain (currently most of western Europe), re-evaluated by a sedimentological and palaeobotanical (megafloras and palynofloras) combined approach. Preservation condition required for fossilization is a limit for dating the upper Permian and lower Triassic sedimentary sequences. As the general climate underwent a major warming phase, the use of fossils as biostratigraphical and palaeoenvironmental tools becomes limited. In these conditions, sedimentary proxies linked to climate can be used instead as valuable correlation tools in continental sections. During the Early Permian, continental sedimentation was limited in a series of isolated endoreic basins, in between differences in preservation and floral assemblages can be observed. This partitionning, at the scale of western Europe, is mainly driven by the Variscan topography. However, the general evolution of Permian flora in the western tethyan domain is still linked at the first order to the global warming event. The general aridification of climates on Pangea led to profound modifications of floras long before the Permian/Triassic biotic crisis. In all sedimentary basins of the north-western tethyan domain, with the exception of the Germanic Basin, the Permian/Triassic transition is characterized by a lack of sedimentary deposition of variable time. This period of no record is associated with: (1) an angular uncomformity of increasing angle towards the axis of the Variscan range, (2) important sedimentary flux at the re-initiation of sedimentation during the Triassic, (3) periods of sedimentation stops indicated by palaeosols, (4) a switch in palaeocurrent direction for fluvial systems between the Permian and the Triassic and, (5) by sedimentary transit and bypass during the lower Triassic. All these observations imply the existence of a still active Variscan range, modifying palaeoclimatic conditions and controlling sedimentation in the end-Permian sedimentary basins of western Europe.

  18. CO2 and the end-Triassic mass extinction.

    PubMed

    Beerling, David

    2002-01-24

    The end of the Triassic period was marked by one of the largest and most enigmatic mass-extinction events in Earth's history and, with few reliable marine geochemical records, terrestrial sediments offer an important means of deciphering environmental changes at this time. Tanner et al. describe an isotopic study of Mesozoic fossil soils which suggests that the atmospheric concentration of carbon dioxide (pCO2) across the Triassic-Jurassic boundary was relatively constant (within 250 p.p.m.v.), but this is inconsistent with high-resolution evidence from the stomatal characters of fossil leaves. Here I show that the temporal resolution of the fossil-soil samples may have been inadequate for detecting a transient rise in pCO2. I also show that the fossil-soil data are consistent with a large increase in pCO2 across the Triassic-Jurassic boundary when variations in the stable carbon isotope (denoted as delta13C) in terrestrial plant leaves are taken into account. These factors suggest that the linkage between pCO2, global warming and the end-Triassic mass extinction remains intact. PMID:11807542

  19. Early Triassic stromatolites as post-mass extinction disaster forms

    SciTech Connect

    Schubert, J.K.; Bottjer, D.J. (Univ. of Southern California, Los Angeles (United States))

    1992-10-01

    Aftermaths of mass extinctions have been thought to be characterized by relaxation of ecological constraints accompanied by increased prominence of opportunistic generalists. Such taxa, termed 'disaster forms,' have been shown to increase dramatically in range and abundance after several mass extinction events. The Cambrian-Ordovician stromatolite decline in normal-marine level-bottom environments has been explained as a direct or indirect consequence of increases in ecological constraints, such as greater levels of predation and/or bioturbation of microbial communities, caused by early Paleozoic benthic invertebrate evolution and diversification. Thus, one would predict that in post-Ordovician strata, stromatolites might appear in normal-marine level-bottom environments as disaster forms in the aftermaths of mass extinction particularly devastating to the benthic biota, such as during Early Triassic time. Mounded stromatolites are present in two beds (up to 1.5 m thick) of the Lower Triassic (Spathian) Virgin Limestone Member (Moenkopi Formation) in the southwestern Spring Mountains of Nevada. Stromatolites from level-bottom normal-marine subtidal environments have also been described from other Lower Triassic strata in North America, Europe, and Asia. These stromatolites, unusual in level-bottom normal-marine settings, may have developed locally during the long aftermath (4-5 m.y.) of the Permian-Triassic mass extinction because of partial relaxation of the ecological constraints that typically restricted them from unstressed subtidal, normal-marine, level-bottom environments.

  20. The time scale of evolutionary innovation.

    PubMed

    Chatterjee, Krishnendu; Pavlogiannis, Andreas; Adlam, Ben; Nowak, Martin A

    2014-09-01

    A fundamental question in biology is the following: what is the time scale that is needed for evolutionary innovations? There are many results that characterize single steps in terms of the fixation time of new mutants arising in populations of certain size and structure. But here we ask a different question, which is concerned with the much longer time scale of evolutionary trajectories: how long does it take for a population exploring a fitness landscape to find target sequences that encode new biological functions? Our key variable is the length, L, of the genetic sequence that undergoes adaptation. In computer science there is a crucial distinction between problems that require algorithms which take polynomial or exponential time. The latter are considered to be intractable. Here we develop a theoretical approach that allows us to estimate the time of evolution as function of L. We show that adaptation on many fitness landscapes takes time that is exponential in L, even if there are broad selection gradients and many targets uniformly distributed in sequence space. These negative results lead us to search for specific mechanisms that allow evolution to work on polynomial time scales. We study a regeneration process and show that it enables evolution to work in polynomial time. PMID:25211329

  1. The Time Scale of Evolutionary Innovation

    PubMed Central

    Chatterjee, Krishnendu; Pavlogiannis, Andreas; Adlam, Ben; Nowak, Martin A.

    2014-01-01

    A fundamental question in biology is the following: what is the time scale that is needed for evolutionary innovations? There are many results that characterize single steps in terms of the fixation time of new mutants arising in populations of certain size and structure. But here we ask a different question, which is concerned with the much longer time scale of evolutionary trajectories: how long does it take for a population exploring a fitness landscape to find target sequences that encode new biological functions? Our key variable is the length, of the genetic sequence that undergoes adaptation. In computer science there is a crucial distinction between problems that require algorithms which take polynomial or exponential time. The latter are considered to be intractable. Here we develop a theoretical approach that allows us to estimate the time of evolution as function of We show that adaptation on many fitness landscapes takes time that is exponential in even if there are broad selection gradients and many targets uniformly distributed in sequence space. These negative results lead us to search for specific mechanisms that allow evolution to work on polynomial time scales. We study a regeneration process and show that it enables evolution to work in polynomial time. PMID:25211329

  2. Mesozoic cyclostratigraphy, the 405-kyr orbital eccentricity metronome, and the Astronomical Time Scale (Invited)

    NASA Astrophysics Data System (ADS)

    Hinnov, L.; Ogg, J. G.

    2009-12-01

    Mesozoic cyclostratigraphy from around the world is being assessed to construct a continuous Astronomical Time Scale (ATS) based on Earth’s cyclic orbital parameters. The recognition of a prevalent sedimentary cycling with a ~400-kyr period associated with forcing by the stable 405-kyr orbital eccentricity variation is an important development. Numerous formations spanning 10 to 20 myr (and longer) intervals in the Cretaceous, Jurassic and Triassic clearly express this dominant cycle and provide a robust basis for 405-kyr-scale calibration of the ATS. This 405-kyr metronome will enable extension of the well-defined Cenozoic ATS for scaling of the past quarter-billion years of Earth history. This astronomical calibration has a resolution comparable to the 1% to 0.1% precision for radioisotope dating of Mesozoic ash beds, with the added benefit of providing continuous stratigraphic coverage between dated beds. Extended portions of the Mesozoic ATS have already provided new insights into long-standing geologic problems of seafloor spreading, tectonics, eustasy, and paleoclimate change. Ongoing work is focused on closing gaps in coverage and on collecting duplicate cyclostratigraphic records for the entire Mesozoic Era.

  3. The hippocampus, time, and memory across scales.

    PubMed

    Howard, Marc W; Eichenbaum, Howard

    2013-11-01

    A wealth of experimental studies with animals have offered insights about how neural networks within the hippocampus support the temporal organization of memories. These studies have revealed the existence of "time cells" that encode moments in time, much as the well-known "place cells" map locations in space. Another line of work inspired by human behavioral studies suggests that episodic memories are mediated by a state of temporal context that changes gradually over long time scales, up to at least a few thousand seconds. In this view, the "mental time travel" hypothesized to support the experience of episodic memory corresponds to a "jump back in time" in which a previous state of temporal context is recovered. We suggest that these 2 sets of findings could be different facets of a representation of temporal history that maintains a record at the last few thousand seconds of experience. The ability to represent long time scales comes at the cost of discarding precise information about when a stimulus was experienced--this uncertainty becomes greater for events further in the past. We review recent computational work that describes a mechanism that could construct such a scale-invariant representation. Taken as a whole, this suggests the hippocampus plays its role in multiple aspects of cognition by representing events embedded in a general spatiotemporal context. The representation of internal time can be useful across nonhippocampal memory systems. PMID:23915126

  4. Lifetimes and time scales in atmospheric chemistry

    Microsoft Academic Search

    Michael J. Prather

    2007-01-01

    Atmospheric composition is controlled by the emission, photochemistry, and transport of many trace gases. Understanding the time-scale as well as the chemical and spatial patterns of perturbations to trace gases is needed to evaluate possible environmental damage (e.g., stratospheric ozone depletion or climate change) caused by anthropogenic emissions. This paper reviews lessons learned from treating global atmospheric chemistry as a

  5. Performance of AERMOD at different time scales

    Microsoft Academic Search

    Bin Zou; F. Benjamin Zhan; J. Gaines Wilson; Yongnian Zeng

    2010-01-01

    As high-density monitoring networks observing pollutant concentrations are costly to establish and maintain, researchers often employ various models to estimate concentrations of air pollutants. The AMS\\/EPA Regulatory Model (AERMOD) is a fairly recent and promising model for estimating concentrations of air pollutants, but the effectiveness of this model at different time scales remains to be verified. This paper evaluates the

  6. Late Permian to Early Triassic magnetostratigraphy

    Microsoft Academic Search

    Maja Haag; Friedrich Heller

    1991-01-01

    A Late Permian to Early Triassic magnetostratigraphic reference section is presented. The Lower Triassic part is based on results from marine limestone sections in South China published earlier [1,2]. Reliable new Permian data are added here which have been collected in the Nammal gorge (Salt Range, Northwest Pakistan) where marine sediments have been deposited quasi-continuously with occasional minor hiatuses during

  7. Low oxygen levels in earliest Triassic soils

    NASA Astrophysics Data System (ADS)

    Sheldon, Nathan D.; Retallack, Gregory J.

    2002-10-01

    An earliest Triassic methane postapocalyptic greenhouse following the Permian-Triassic (P-T) extinction event was proposed on the basis of evidence of deeply weathered paleosols at high latitudes with features of low-latitude soils, and low stomatal index values of seed fern leaves. Reexamination of distinctive phyllosilicates, unique to a single stratigraphic level, in paleosols located just above the isotopically defined Permian-Triassic boundary in Australia and Antarctica furnishes additional tests of this hypothesis. Illite is the dominant clay mineral in earliest Triassic paleosols from Antarctica, but the paleosols also contain conspicuous green nodules of coarsely crystalline berthierine. Examples from the geologic record and from experimental studies indicate that the formation of berthierine is restricted to reducing conditions. The occurrence of this unusual mineral in soils may indicate soil oxygen consumption by the influx of atmospheric methane to form carbon dioxide, which in turn warmed the earliest Triassic, giving rise to a postapocalyptic greenhouse.

  8. A comment on the use of flushing time, residence time, and age as transport time scales

    USGS Publications Warehouse

    Monsen, N.E.; Cloern, J.E.; Lucas, L.V.; Monismith, S.G.

    2002-01-01

    Applications of transport time scales are pervasive in biological, hydrologic, and geochemical studies yet these times scales are not consistently defined and applied with rigor in the literature. We compare three transport time scales (flushing time, age, and residence time) commonly used to measure the retention of water or scalar quantities transported with water. We identify the underlying assumptions associated with each time scale, describe procedures for computing these time scales in idealized cases, and identify pitfalls when real-world systems deviate from these idealizations. We then apply the time scale definitions to a shallow 378 ha tidal lake to illustrate how deviations between real water bodies and the idealized examples can result from: (1) non-steady flow; (2) spatial variability in bathymetry, circulation, and transport time scales; and (3) tides that introduce complexities not accounted for in the idealized cases. These examples illustrate that no single transport time scale is valid for all time periods, locations, and constituents, and no one time scale describes all transport processes. We encourage aquatic scientists to rigorously define the transport time scale when it is applied, identify the underlying assumptions in the application of that concept, and ask if those assumptions are valid in the application of that approach for computing transport time scales in real systems.

  9. Carbon-cycle disturbances and environmental change preceding the end-Triassic mass extinction

    NASA Astrophysics Data System (ADS)

    Ruhl, M.; Ullmann, C. V.; Mette, W.; Korte, C.

    2012-04-01

    The end-Triassic mass extinction [~201.3 Ma], marked by marine and terrestrial ecosystem collapse and global marine biodiversity loss, coincides with the onset of extensive volcanic activity and emplacement of the Central Atlantic Magmatic Province (CAMP). Massive and rapid greenhouse gas release from basalts, subsurface organic rich strata and ocean-floor clathrates, had a profound impact on the global exogenic carbon cycle and caused dramatically increased atmospheric pCO2 values. A recent study however suggests global carbon cycle disturbance already (possibly ~100 kyr) before the end-Triassic mass extinction. 13C depleted atmospheric carbon injection at this event may have resulted from Late Triassic dike and sill intrusions possibly releasing thermogenic methane from subsurface organic-rich sediments. We now studied an extended, up to 1 million year long, Late Triassic marine sedimentary record from the western Tethian Eiberg basin (Northern Calcareous Alps, Austria). Sediments were deposited in the deepest part of the Eiberg basin (very close to the base Jurassic Global Stratotype Section and Point at Kuhjoch). High-resolution ?13CTOC, ?13CCARB-Bulk and ?13CCARB-Brachiopods from this record show distinct 1-2‰ ?13C negative excursions throughout the latest Triassic. This suggests disturbance of the global exogenic carbon cycle already long before the end-Triassic mass extinction. Regular alternations between (laminated) black-shales and carbonate deposition also indicate periodic changes in the palaeo-environment. Variations in the ?18OCARB record, coinciding with ?13C negative excursions, suggest climatic warming. But, distinct negative shifts may also indicate increased fresh-water input along the upper-Triassic western Tethys continental margin. Volcanic activity and palaeo-environmental change occurring already before the end-Triassic mass extinction, may have progressively weakened marine ecosystems, ultimately leading to large-scale marine biodiversity loss.

  10. Accuracy metrics for judging time scale algorithms

    NASA Technical Reports Server (NTRS)

    Douglas, R. J.; Boulanger, J.-S.; Jacques, C.

    1994-01-01

    Time scales have been constructed in different ways to meet the many demands placed upon them for time accuracy, frequency accuracy, long-term stability, and robustness. Usually, no single time scale is optimum for all purposes. In the context of the impending availability of high-accuracy intermittently-operated cesium fountains, we reconsider the question of evaluating the accuracy of time scales which use an algorithm to span interruptions of the primary standard. We consider a broad class of calibration algorithms that can be evaluated and compared quantitatively for their accuracy in the presence of frequency drift and a full noise model (a mixture of white PM, flicker PM, white FM, flicker FM, and random walk FM noise). We present the analytic techniques for computing the standard uncertainty for the full noise model and this class of calibration algorithms. The simplest algorithm is evaluated to find the average-frequency uncertainty arising from the noise of the cesium fountain's local oscillator and from the noise of a hydrogen maser transfer-standard. This algorithm and known noise sources are shown to permit interlaboratory frequency transfer with a standard uncertainty of less than 10(exp -15) for periods of 30-100 days.

  11. Cyclostratigraphy of the Middle Triassic bedded chert sequence in the Chichibu Belt, Southwest Japan

    NASA Astrophysics Data System (ADS)

    Soda, K.; Onoue, T.; Ikeda, M.

    2014-12-01

    Triassic bedded cherts from the Jurassic accretionary complexes in Japan consist of centimeter scale alternations of chert and shale beds. Previous studies have proposed that the rhythmical alternations of Triassic chert and shale beds represent astronomical cycles. Although cyclostratigraphy of the Triassic bedded chert sequence was identified in the Inuyama area of the Mino Belt, central Japan, the validity of its cyclostratigraphy requires detailed cyclostratigraphic correlations to other Triassic bedded chert sequences in Japan. In this study, we performed cyclostratigraphic analysises to the Middle Triassic (Anisian-Ladinian) bedded chert sequence in the Tsukumi area of the Chichibu Belt, southwest Japan. The average duration of a chert-shale couplet in the Middle Triassic bedded chert of the Tsukumi area is ~10 kyr. This duration is inconsistent with the ~20 kyr duration of the precession cycle during the Triassic, which was confirmed by estimated average duration of a chert-shale couplet in the Triassic bedded chert of the Inuyama area. The dominat cycles in a bed number series of thickness variations in the Middle Triassic chert beds show approximately 2-5, 10, 40, 200, 300 and 400 beds cycles. Given that the average duration of one chert-shale couplet is 10 kyr, these cycles correspond to approximately 20-50, 100, 400, 2000, 3000 and 4000 kyr periodicities. The periodicities of the Tsukumi chert are consistent with those of the Inuyama chert (approximately 40-60, 100, 140, 240, 400 and 4000 kyr). Previous paleomagnetic studies have revealed that the Middle Triassic bedded cherts in the Tsukumi area were deposited in the equatorial region (2.1°±5.2°S), whereas the deposition of the Inuyama cherts occur at relatively higher latitude (16.9°±10.2°N). If the interpretation that rhythmical alternations of chert and shale beds are paced by precession and eccentricity cycles is valid, the average duration of a chet-shale couplet from the Tsukumi area might reflect the semi-precession cycle (~10 kyr) in the equator area caused by biannual passage of the Sun. Further cyclostratigraphic analysises will requires to estimate the paleolatitudinally dependent patterns in the cyclicities of the Triassic bedded chert sequences in Japan.

  12. Short-time scale behavior modeling within long-time scale fuel cycle evaluations

    SciTech Connect

    Johnson, M.; Tsvetkov, P. [Dept. of Nuclear Engineering, Texas A and M Univ., 3133 TAMU, College Station, TX 77843 (United States); Lucas, S. [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415 (United States)

    2012-07-01

    Typically, short-time and long-time scales in nuclear energy system behavior are accounted for with entirely separate models. However, long-term changes in system characteristics do affect short-term transients through material variations. This paper presents an approach to consistently account for short-time scales within a nuclear system lifespan. The reported findings and developments are of significant importance for small modular reactors and other nuclear energy systems operating in autonomous modes. It is necessary to simulate the short time-scale kinetic behavior of the reactor as well as the long time-scale dynamics that occur with fuel burnup. The former is modeled using the point kinetics equations, while the latter is modeled by the Bateman equations. (authors)

  13. Towards a quaternary time scale*1

    NASA Astrophysics Data System (ADS)

    Berggren, W. A.; Burckle, L. H.; Cita, M. B.; Cooke, H. B. S.; Funnell, B. M.; Gartner, S.; Hays, J. D.; Kennett, J. P.; Opdyke, N. D.; Pastouret, L.; Shackleton, N. J.; Takayanagi, Y.

    1980-05-01

    Nine first-appearance datums (FADs), twenty-three last-appearance datums (LADs), and three other micropaleontological datums are related to the magnetic-reversal, oxygen-isotope, and calcite-dissolution/coarse-fraction time scales to provide a preliminary basis for subdivision of the Quaternary in deep-sea sediments. The magnetic-reversal, oxygen-isotope, and calcite-dissolution/coarse-fraction scales have been correlated by determination on the same core materials, and absolute dates applied by {40K}/{40Ar} or 14C dating of materials in known positions on one or another of these scales. FADS and LADs have been determined in cores for which either a magnetic-reversal, oxygen-isotope, or calcite-dissolution/coarse-fraction scale has also been available. Altogether 3 FADs and 5 LADs based on diatoms, 4 FADs and 5 LADs based on calcareous nannoplankton, 1 FAD and 8 LADs based on radiolarians, 1 FAD and 5 LADs based on planktonic foraminifers, 2 acme datums, and 1 ratio reversal datum have been determined, and absolute dates inferred by interpolation from known dates on the reference time scales. Some of the FADs and LADs apply or are synchronous only over limited areas of the oceans; others appear to be synchronous throughout the oceans. The base of the Quaternary is set at the top of the Olduvai event at 1.7 my. Four FADs, twelve LADs, two acme datums, and one ratio reversal datum occur above the base of the Quaternary at an average rate of about 1 per 100,000 yr. Five FADs and twelve LADs are recognized in the 0.8-my interval between the top of the Olduvai event and the Gauss/Matuyama Boundary at 2.5 my at an average incidence of about 1 per 50,000 yr.

  14. Time ephemeris and general relativistic scale factor

    NASA Astrophysics Data System (ADS)

    Fukushima, Toshio

    2010-01-01

    Time ephemeris is the location-independent part of the transformation formula relating two time coordinates such as TCB and TCG (Fukushima 1995). It is computed from the corresponding (space) ephemerides providing the relative motion of two spatial coordinate origins such as the motion of geocenter relative to the solar system barycenter. The time ephemerides are inevitably needed in conducting precise four dimensional coordinate transformations among various spacetime coordinate systems such as the GCRS and BCRS (Soffel et al. 2003). Also, by means of the time average operation, they are used in determining the information on scale conversion between the pair of coordinate systems, especially the difference of the general relativistic scale factor from unity such as LC. In 1995, we presented the first numerically-integrated time ephemeris, TE245, from JPL's planetary ephemeris DE245 (Fukushima 1995). It gave an estimate of LC as 1.4808268457(10) × 10-8, which was incorrect by around 2 × 10-16. This was caused by taking the wrong sign of the post-Newtonian contribution in the final summation. Four years later, we updated TE245 to TE405 associated with DE405 (Irwin and Fukushima 1999). This time the renewed vale of LC is 1.48082686741(200) × 10-8 Another four years later, by using a precise technique of time average, we improved the estimate of Newtonian part of LC for TE405 as 1.4808268559(6) × 10-8 (Harada and Fukushima 2003). This leads to the value of LC as LC = 1.48082686732(110) × 10-8. If we combine this with the constant defining the mean rate of TCG-TT, LG = 6.969290134 × 10-10 (IAU 2001), we estimate the numerical value of another general relativistic scale factor LB = 1.55051976763(110) × 10-8, which has the meaning of the mean rate of TCB-TT. The main reasons of the uncertainties are the truncation effect in time average and the uncertainty of asteroids' perturbation. The former is a natural limitation caused by the finite length of numerical planetary ephemerides and the latter is due to the uncertainty of masses of some heavy asteroids. As a compact realization of the time ephemeris, we prepared HF2002, a Fortran routine to compute approximate harmonic series of TE405 with the RMS error of 0.446 ns for the period 1600 to 2200 (Harada and Fukushima 2003). It is included in the IERS Convention 2003 (McCarthy and Petit 2003) and available from the IERS web site; http://tai.bipm.org/iers/conv2003/conv2003_c10.html.

  15. South Atlantic Spreading Velocities and Time Scales

    NASA Astrophysics Data System (ADS)

    Clark, S. R.; Smethurst, M. A.; Bianchi, M. C.

    2013-12-01

    Plate reconstructions based on hierarchical spherical rotations have been around for many years. For the breakup of Pangea and Gondwana, these reconstructions are based on two major sources: magnetic isochrons and geological evidence for the onset of rifting and the tightness of the fit between continents. These reconstructions imply spreading velocities and it is the changes in velocities that can be used to probe questions of the forces moving plates around. In order to calculate the velocities correctly though, the importance of the choice of geologic time scale is often ignored. In this talk, we focus on the South Atlantic and calculate the spreading velocity errors implied by the choice of time scale for three major epochs: the Cenozoic and Late Mesozoic, the Cretaceous Quiet Zone and the Late Cretaceous to the Early Jurassic. In addition, we report the spreading velocities implied through these phases by various available magnetic isochron-derived reconstructions and the geological fits for South America and Africa used by large scale global reconstruction as well as in recent papers. Finally, we will highlight the implications for the choice of the mantle reference frame on African plate velocities.

  16. New Early Jurassic Tetrapod Assemblages Constrain Triassic-Jurassic Tetrapod Extinction Event

    NASA Astrophysics Data System (ADS)

    Olsen, P. E.; Shubin, N. H.; Anders, M. H.

    1987-08-01

    The discovery of the first definitively correlated earliest Jurassic (200 million years before present) tetrapod assemblage (Fundy basin, Newark Supergroup, Nova Scotia) allows reevaluation of the duration of the Triassic-Jurassic tetrapod extinction event. Present are tritheledont and mammal-like reptiles, prosauropod, theropod, and ornithischian dinosaurs, protosuchian and sphenosuchian crocodylomorphs, sphenodontids, and hybodont, semionotid, and palaeonisciform fishes. All of the families are known from Late Triassic and Jurassic strata from elsewhere; however, pollen and spore, radiometric, and geochemical correlation indicate an early Hettangian age for these assemblages. Because all ``typical Triassic'' forms are absent from these assemblages, most Triassic-Jurassic tetrapod extinctions occurred before this time and without the introduction of new families. As was previously suggested by studies of marine invertebrates, this pattern is consistent with a global extinction event at the Triassic-Jurassic boundary. The Manicouagan impact structure of Quebec provides dates broadly compatible with the Triassic-Jurassic boundary and, following the impact theory of mass extinctions, may be implicated in the cause.

  17. Scaling laws from geomagnetic time series

    USGS Publications Warehouse

    Voros, Z.; Kovacs, P.; Juhasz, A.; Kormendi, A.; Green, A.W.

    1998-01-01

    The notion of extended self-similarity (ESS) is applied here for the X - component time series of geomagnetic field fluctuations. Plotting nth order structure functions against the fourth order structure function we show that low-frequency geomagnetic fluctuations up to the order n = 10 follow the same scaling laws as MHD fluctuations in solar wind, however, for higher frequencies (f > l/5[h]) a clear departure from the expected universality is observed for n > 6. ESS does not allow to make an unambiguous statement about the non triviality of scaling laws in "geomagnetic" turbulence. However, we suggest to use higher order moments as promising diagnostic tools for mapping the contributions of various remote magnetospheric sources to local observatory data. Copyright 1998 by the American Geophysical Union.

  18. The Geologic Time Scale: The Development of Life through time

    NSDL National Science Digital Library

    This text assists in understanding time relationships and how life on Earth has changed over time. The dates shown were compiled from several available sources. The first page shows some important events in Earth history, presented in the order in which they occurred. The data are also shown on the scale of a calendar year. On the second sheet is a chart showing the geologic eras, systems, and series. On the chart, each dot, number, or letter represents 1 million years. The dots get older as you read down the chart, or to the right along a row. They represent millions of years before present (mybp) and show the ages of the oldest known fossils of selected animals or the time of an event. Not all of the items are shown on the chart because of space limitations.

  19. Time scales in nuclear giant resonances

    E-print Network

    WD Heiss; RG Nazmitdinov; FD Smit

    2009-12-18

    We propose a general approach to characterise fluctuations of measured cross sections of nuclear giant resonances. Simulated cross sections are obtained from a particular, yet representative self-energy which contains all information about fragmentations. Using a wavelet analysis, we demonstrate the extraction of time scales of cascading decays into configurations of different complexity of the resonance. We argue that the spreading widths of collective excitations in nuclei are determined by the number of fragmentations as seen in the power spectrum. An analytic treatment of the wavelet analysis using a Fourier expansion of the cross section confirms this principle. A simple rule for the relative life times of states associated with hierarchies of different complexity is given.

  20. Time-scale for accretion of matter

    E-print Network

    F. Combes

    1998-11-09

    Mass accretion is the key factor for evolution of galaxies. It can occur through secular evolution, when gas in the outer parts is driven inwards by dynamical instabilities, such as spirals or bars. This secular evolution proceeds very slowly when spontaneous, and can be accelerated when triggered by companions. Accretion can also occur directly through merging of small companions, or more violent interaction and coalescence. We discuss the relative importance of both processes, their time-scale and frequency along a Hubble time. Signatures of both processes can be found in the Milky Way. It is however likely that our Galaxy had already gathered the bulk of its mass about 8-10 Gyr ago, as is expected in hierarchical galaxy formation scenarios.

  1. Uppermost permian reefs and permo-triassic sedimentary facies from the southeastern margin of Sichuan Basin, China

    Microsoft Academic Search

    Joachim W. Reinhardt

    1988-01-01

    Summary  A large-scale, gradual transition from an epicontinental marine regime, prevailing during most of the Paleozoic, to continental\\u000a (?molasse) red beds of Upper Triassic and younger age is documented within the Permo-Triassic sequence of marine carbonate\\u000a and siliciclastic rocks of the western Yangzi Platform in southern China. Large portions of the Yangzi Platform (along with\\u000a the Tarim and Sino-Korea Platforms, one

  2. The Triassic detrital units in the East-Mediterranean realm: back-arcs opening and Cimmerian collision

    NASA Astrophysics Data System (ADS)

    Moix, P.; Stampfli, G. M.

    2009-04-01

    Late Permian and principally Triassic detrital units play an important role in deciphering the geodynamic evolution of the East-Mediterranean area. Some of these units are related to diffuse rifting along the southern margin of Eurasia, whereas others reflect the Cimmerian collision between Gondwana and post-Variscan Eurasia-derived terranes. Several differences within these Triassic detrital units should be noted: they have a different timing of deposition, they are found in autochthonous, para-autochthonous or allochthonous position, and they have different types of substratum and cover series. In addition, the nature of the recycled material is also decisive to make the difference between orogen and rift-related sediments. The investigated sandstones, breccias and conglomerates usually range in age from the Anisian (Scythian?) to the Late Triassic (sometimes Liassic) and are especially well-developed during the Carnian-Norian interval. From the Late Permian to the Late Triassic, the Variscan Cordillera was affected by orogen-scale collapse, leading to widespread rifting, related to slab roll-back of the northward subducting Palaeotethys. This provoked the opening of a series of back-arc basins (i.e. Meliata-Hallstatt, Maliac and Pindos oceans). At the same time, this subduction detached by slab-pull a series of Cimmerian terranes along the northern border of Gondwana and opened the Neotethys to the south of them. The final closure of the Palaeotethys (Cimmerian Event) between the Taurus and the Anatolian terranes produced at places large flysch-molasse deposits often sealed by Jurassic platforms. In southern Europe, the diffuse rifting along the southern margin of Eurasia is recognized in the Carnic Alps. The Carboniferous fore-arc flysch basin (Hochwipfel and Dimon fms) is sealed by a shallow-water sequence of Pennsylvanian-Early Permian age (Pramolo, Rattendorf and Trogkofel groups). The Late Permian rifting is marked by the deposition of the Val Gardena Sandstone and the Bellerophon Fm. This rifting phase is sealed by the Werfen Fm. and the Serla Dolomite. The second phase of rifting is marked by the deposition of the Braies group during the upper Anisian (locally sealed by the latest Anisian-early Carnian Sciliar Dolomite), followed by the deposition of the Buchenstein ("Pietra Verde" pro parte), Wengen (turbiditic sandstones) and San Cassiano Fms until the lower Carnian. This second episode is locally sealed by the Cassian Dolomite and the Val Degano Fm. The third rifting phase is marked by the deposition of the Carnian Dürrenstein Fm, sealed by the late Carnian Raibl Fm. and the Norian Dolomia Principale. On the Turkish transect, the detrital units belonging to the allochthonous series are post-Variscan Anatolian-derived nappes and are often associated with widespread volcanism. They are generally situated at the base of sequences showing shallow marine sedimentation that pass up to pelagic conditions and finish with flysch/wildflysch deposits. The Meliata-Hallstatt "signal" is well-known in the Silická Brezová composite section (Slovakia). The lower to middle Carnian is made of shallow water limestone followed by a rapid subsidence during the lower upper Carnian and the deposition of pelagic limestones, crinoid limestones, calcarenites and micrites themselves followed by Hallstatt Limestones during the entire Norian and lower Rhaetian. The Maliac "signal" is clearly identifiable in the Karaburun Peninsula. The pelagic development made of limestones and radiolarites usually starts during the Spathian above shallow water limestones. The pelagic sedimentation continues during the middle Triassic and the lower Carnian. During the middle Carnian, the sedimentation passes to shallow water limestones and this situation persists during the Upper Triassic and sometimes even higher up. Volcanic events are common in the Spathian and in the Middle Triassic. Late Carnian cherts associated with pillow-lavas of Maliac origin are found on the northern edge of the composite Anatolian-Tauric plat

  3. Parametric instabilities in picosecond time scales

    SciTech Connect

    Baldis, H.A. [Lawrence Livermore National Lab., CA (United States); Rozmus, W. [Alberta Univ., Edmonton, AB (Canada). Dept. of Physics; Labaune, C.; Mounaix, Ph.; Pesme, D.; Baton, S. [Ecole Polytechnique, Palaiseau (France); Tikhonchuk, V.T. [P.N. Lebedev Physics Inst., Moscow (Russian Federation)

    1993-03-01

    The coupling of intense laser light with plasmas is a rich field of plasma physics, with many applications. Among these are inertial confinement fusion (ICF), x-ray lasers, particle acceleration, and x-ray sources. Parametric instabilities have been studied for many years because of their importance to ICF; with laser pulses with duration of approximately a nanosecond, and laser intensities in the range 10{sup 14}--10{sup 15}W/cm{sup 2} these instabilities are of crucial concern because of a number of detrimental effects. Although the laser pulse duration of interest for these studies are relatively long, it has been evident in the past years that to reach an understanding of these instabilities requires their characterization and analysis in picosecond time scales. At the laser intensities of interest, the growth rate for stimulated Brillouin scattering (SBS) is of the order of picoseconds, and of an order of magnitude shorter for stimulated Raman scattering (SRS). In this paper the authors discuss SBS and SRS in the context of their evolution in picosecond time scales. They describe the fundamental concepts associated with their growth and saturation, and recent work on the nonlinear treatment required for the modeling of these instabilities at high laser intensities.

  4. Early Triassic marine biotic recovery: the predators' perspective.

    PubMed

    Scheyer, Torsten M; Romano, Carlo; Jenks, Jim; Bucher, Hugo

    2014-01-01

    Examining the geological past of our planet allows us to study periods of severe climatic and biological crises and recoveries, biotic and abiotic ecosystem fluctuations, and faunal and floral turnovers through time. Furthermore, the recovery dynamics of large predators provide a key for evaluation of the pattern and tempo of ecosystem recovery because predators are interpreted to react most sensitively to environmental turbulences. The end-Permian mass extinction was the most severe crisis experienced by life on Earth, and the common paradigm persists that the biotic recovery from the extinction event was unusually slow and occurred in a step-wise manner, lasting up to eight to nine million years well into the early Middle Triassic (Anisian) in the oceans, and even longer in the terrestrial realm. Here we survey the global distribution and size spectra of Early Triassic and Anisian marine predatory vertebrates (fishes, amphibians and reptiles) to elucidate the height of trophic pyramids in the aftermath of the end-Permian event. The survey of body size was done by compiling maximum standard lengths for the bony fishes and some cartilaginous fishes, and total size (estimates) for the tetrapods. The distribution and size spectra of the latter are difficult to assess because of preservation artifacts and are thus mostly discussed qualitatively. The data nevertheless demonstrate that no significant size increase of predators is observable from the Early Triassic to the Anisian, as would be expected from the prolonged and stepwise trophic recovery model. The data further indicate that marine ecosystems characterized by multiple trophic levels existed from the earliest Early Triassic onwards. However, a major change in the taxonomic composition of predatory guilds occurred less than two million years after the end-Permian extinction event, in which a transition from fish/amphibian to fish/reptile-dominated higher trophic levels within ecosystems became apparent. PMID:24647136

  5. Early Triassic Marine Biotic Recovery: The Predators' Perspective

    PubMed Central

    Scheyer, Torsten M.; Romano, Carlo; Jenks, Jim; Bucher, Hugo

    2014-01-01

    Examining the geological past of our planet allows us to study periods of severe climatic and biological crises and recoveries, biotic and abiotic ecosystem fluctuations, and faunal and floral turnovers through time. Furthermore, the recovery dynamics of large predators provide a key for evaluation of the pattern and tempo of ecosystem recovery because predators are interpreted to react most sensitively to environmental turbulences. The end-Permian mass extinction was the most severe crisis experienced by life on Earth, and the common paradigm persists that the biotic recovery from the extinction event was unusually slow and occurred in a step-wise manner, lasting up to eight to nine million years well into the early Middle Triassic (Anisian) in the oceans, and even longer in the terrestrial realm. Here we survey the global distribution and size spectra of Early Triassic and Anisian marine predatory vertebrates (fishes, amphibians and reptiles) to elucidate the height of trophic pyramids in the aftermath of the end-Permian event. The survey of body size was done by compiling maximum standard lengths for the bony fishes and some cartilaginous fishes, and total size (estimates) for the tetrapods. The distribution and size spectra of the latter are difficult to assess because of preservation artifacts and are thus mostly discussed qualitatively. The data nevertheless demonstrate that no significant size increase of predators is observable from the Early Triassic to the Anisian, as would be expected from the prolonged and stepwise trophic recovery model. The data further indicate that marine ecosystems characterized by multiple trophic levels existed from the earliest Early Triassic onwards. However, a major change in the taxonomic composition of predatory guilds occurred less than two million years after the end-Permian extinction event, in which a transition from fish/amphibian to fish/reptile-dominated higher trophic levels within ecosystems became apparent. PMID:24647136

  6. Atmospheric methane injection caused end-Triassic mass extinction

    NASA Astrophysics Data System (ADS)

    Ruhl, Micha; Bonis, Nina R.; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S.; Kürschner, Wolfram M.

    2010-05-01

    The end-Triassic mass extinction (~201.5 Ma), marked by major terrestrial ecosystem changes and a 50% loss in marine biodiversity, coincides with a distinct negative perturbation in marine C-isotope records. These events have been attributed to the onset of intensified volcanic activity in the Central Atlantic Magmatic Province (CAMP), the largest igneous province on earth. However, global carbon cycle disruption has been questioned due to varying magnitudes of the observed negative excursion between different sedimentary basins. Here, we present compound specific C-isotope data of long-chain n-alkanes derived from waxes of land plants, showing a ~8.5‰ negative excursion coincident with the extinction interval. These data suggest strong 13C depletion of the end-Triassic atmosphere, within 10-20 kyr. The magnitude and rate of C-cycle disruption can only be explained by the injection of ~12x103 Gt of isotopically depleted carbon from the methane-hydrate reservoir. Concurrent vegetation changes reflect strong warming and an enhanced hydrological cycle. Hence the end-Triassic extinction is, for the first time, mechanistically linked to massive carbon release and associated climate change.

  7. Osmium isotope evidence for a large Late Triassic impact event

    PubMed Central

    Sato, Honami; Onoue, Tetsuji; Nozaki, Tatsuo; Suzuki, Katsuhiko

    2013-01-01

    Anomalously high platinum group element concentrations have previously been reported for Upper Triassic deep-sea sediments, which are interpreted to be derived from an extraterrestrial impact event. Here we report the osmium (Os) isotope fingerprint of an extraterrestrial impact from Upper Triassic chert successions in Japan. Os isotope data exhibit a marked negative excursion from an initial Os isotope ratio (187Os/188Osi) of ?0.477 to unradiogenic values of ?0.126 in a platinum group element-enriched claystone layer, indicating the input of meteorite-derived Os into the sediments. The timing of the Os isotope excursion coincides with both elevated Os concentrations and low Re/Os ratios. The magnitude of this negative Os isotope excursion is comparable to those found at Cretaceous–Paleogene boundary sites. These geochemical lines of evidence demonstrate that a large impactor (3.3–7.8?km in diameter) produced a global decrease in seawater 187Os/188Os ratios in the Late Triassic. PMID:24036603

  8. EDITORIAL: Special issue on time scale algorithms

    NASA Astrophysics Data System (ADS)

    Matsakis, Demetrios; Tavella, Patrizia

    2008-12-01

    This special issue of Metrologia presents selected papers from the Fifth International Time Scale Algorithm Symposium (VITSAS), including some of the tutorials presented on the first day. The symposium was attended by 76 persons, from every continent except Antarctica, by students as well as senior scientists, and hosted by the Real Instituto y Observatorio de la Armada (ROA) in San Fernando, Spain, whose staff further enhanced their nation's high reputation for hospitality. Although a timescale can be simply defined as a weighted average of clocks, whose purpose is to measure time better than any individual clock, timescale theory has long been and continues to be a vibrant field of research that has both followed and helped to create advances in the art of timekeeping. There is no perfect timescale algorithm, because every one embodies a compromise involving user needs. Some users wish to generate a constant frequency, perhaps not necessarily one that is well-defined with respect to the definition of a second. Other users might want a clock which is as close to UTC or a particular reference clock as possible, or perhaps wish to minimize the maximum variation from that standard. In contrast to the steered timescales that would be required by those users, other users may need free-running timescales, which are independent of external information. While no algorithm can meet all these needs, every algorithm can benefit from some form of tuning. The optimal tuning, and even the optimal algorithm, can depend on the noise characteristics of the frequency standards, or of their comparison systems, the most precise and accurate of which are currently Two Way Satellite Time and Frequency Transfer (TWSTFT) and GPS carrier phase time transfer. The interest in time scale algorithms and its associated statistical methodology began around 40 years ago when the Allan variance appeared and when the metrological institutions started realizing ensemble atomic time using more than one single atomic clock. An international symposium dedicated to these topics was initiated in 1972 as the first International Symposium on Atomic Time Scale Algorithms and it was the beginning of a series: 1st Symposium: organized at the NIST (NBS at that epoch) in 1972, 2nd Symposium: again at the NIST in 1982, 3rd Symposium: in Italy at the INRIM (IEN at that epoch) in 1988, 4th Symposium: in Paris at the BIPM in 2002 (see Metrologia 40 (3), 2003) 5th Symposium: in San Fernando, Spain at the ROA in 2008. The early symposia were concerned with establishing the basics of how to estimate and characterize the behavior of an atomic frequency standard in an unambiguous and clearly identifiable way, and how to combine the reading of different clocks to form an optimal time scale within a laboratory. Later, as atomic frequency standards began to be used as components in larger systems, interest grew in understanding the impact of a clock in a more complex environment. For example, use of clocks in telecommunication networks in a Synchronous Digital Hierarchy created a need to measure the maximum time error spanned by a clock in a certain interval. Timekeeping metrologists became interested in estimating time deviations and time stability, so they had to find ways to convert their common frequency characteristics to time characteristics. Tests of fundamental physics provided a motivation for launching atomic frequency standards into space in long-lasting missions, whose high-precision measurements might be available for only a few hours a day, yielding a series of clock data with many gaps and outliers for which a suitable statistical analysis was necessary to extract as much information as possible from the data. In the 21st century, the field has been transformed by the advent of atomic-clock-based Global Navigation Satellite Systems (GNSS), the steady increase in precision brought about by rapidly improving clocks and measurement systems, and the growing number of relatively inexpensive small clock ensembles. Although technological transformations have raised the

  9. Time scales in nuclear giant resonances

    SciTech Connect

    Heiss, W. D. [National Institute for Theoretical Physics, Stellenbosch Institute for Advanced Study, and Institute of Theoretical Physics, University of Stellenbosch, 7602 Matieland (South Africa); Nazmitdinov, R. G. [Department de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation); Smit, F. D. [iThemba LABS, Post Office Box 722, Somerset West 7129 (South Africa)

    2010-03-15

    We propose a general approach to characterise fluctuations of measured cross sections of nuclear giant resonances. Simulated cross sections are obtained from a particular, yet representative, self-energy that contains all information about fragmentations. Using a wavelet analysis, we demonstrate the extraction of time scales of cascading decays into configurations of different complexity of the resonance. We argue that the spreading widths of collective excitations in nuclei are determined by the number of fragmentations as seen in the power spectrum. An analytic treatment of the wavelet analysis using a Fourier expansion of the cross section confirms this principle. A simple rule for the relative lifetimes of states associated with hierarchies of different complexity is given.

  10. Corrected Late Triassic latitudes for continents adjacent to the North Atlantic.

    PubMed

    Kent, Dennis V; Tauxe, Lisa

    2005-01-14

    We use a method based on a statistical geomagnetic field model to recognize and correct for inclination error in sedimentary rocks from early Mesozoic rift basins in North America, Greenland, and Europe. The congruence of the corrected sedimentary results and independent data from igneous rocks on a regional scale indicates that a geocentric axial dipole field operated in the Late Triassic. The corrected paleolatitudes indicate a faster poleward drift of approximately 0.6 degrees per million years for this part of Pangea and suggest that the equatorial humid belt in the Late Triassic was about as wide as it is today. PMID:15653500

  11. Detection of crossover time scales in multifractal detrended fluctuation analysis

    NASA Astrophysics Data System (ADS)

    Ge, Erjia; Leung, Yee

    2013-04-01

    Fractal is employed in this paper as a scale-based method for the identification of the scaling behavior of time series. Many spatial and temporal processes exhibiting complex multi(mono)-scaling behaviors are fractals. One of the important concepts in fractals is crossover time scale(s) that separates distinct regimes having different fractal scaling behaviors. A common method is multifractal detrended fluctuation analysis (MF-DFA). The detection of crossover time scale(s) is, however, relatively subjective since it has been made without rigorous statistical procedures and has generally been determined by eye balling or subjective observation. Crossover time scales such determined may be spurious and problematic. It may not reflect the genuine underlying scaling behavior of a time series. The purpose of this paper is to propose a statistical procedure to model complex fractal scaling behaviors and reliably identify the crossover time scales under MF-DFA. The scaling-identification regression model, grounded on a solid statistical foundation, is first proposed to describe multi-scaling behaviors of fractals. Through the regression analysis and statistical inference, we can (1) identify the crossover time scales that cannot be detected by eye-balling observation, (2) determine the number and locations of the genuine crossover time scales, (3) give confidence intervals for the crossover time scales, and (4) establish the statistically significant regression model depicting the underlying scaling behavior of a time series. To substantive our argument, the regression model is applied to analyze the multi-scaling behaviors of avian-influenza outbreaks, water consumption, daily mean temperature, and rainfall of Hong Kong. Through the proposed model, we can have a deeper understanding of fractals in general and a statistical approach to identify multi-scaling behavior under MF-DFA in particular.

  12. The Inception of the Colorado Plateau Coring Project: Filling the Triassic Geochronologic Gap and Providing a Continuous Record of Continental Environmental Change in Western Equatorial Pangea

    NASA Astrophysics Data System (ADS)

    Geissman, J. W.; Olsen, P. E.; Kent, D. V.; Irmis, R. B.; Gehrels, G. E.; Mundil, R.; Parker, W.; Bachmann, G. H.; Kurschner, W. M.; Sha, J.

    2014-12-01

    The Triassic Period was punctuated by two of the largest Phanerozoic mass-extinctions and witnessed the evolution of elements of the modern biota and the advent of the age of dinosaurs. A rich archive of biotic and environmental changes on land for the early Mesozoic is on the Colorado Plateau, which despite over 100 years of study still remains poorly calibrated in time and poorly registered to other global records. Over 15 years ago, a diverse team of scientists began to develop the concept of a multi-phase, long term Colorado Plateau Coring Project (CPCP). Planning involved two major meetings (DOSECC/NSFICDP supported in Fall, 2007, St. George, UT; and International Continental Drilling Program (ICDP) supported in Spring, 2009, Albuquerque, NM). The National Park Service embraced the concept of Phase One drilling at Petrified Forest National Park (PFNP) in northern Arizona, which exposes one of the most famous and best studied successions of the continental Triassic on Earth, and the Phase One target was decided. Most drilling operation costs were secured from ICDP in Summer, 2010. In late 2013, following more recent NSF support, the research team, utilizing Ruen Drilling Inc., drilled a continuous ~530 m core (60o plunge) through the entire section of Triassic strata (Chinle and Moenkopi fms.) in the north end and a ~240 m core (75o plunge) in lower Chinle and all Moenkopi strata at the south end of the PFNP. Our continuous sampling will place this record in a reliable quantitative and exportable time scale, as a reference section in which magnetostratigraphic, geochronologic, environmental, and paleontologic data are registered to a common thickness scale with unambiguous superposition using pristine samples. The cores are being scanned at the High Resolution X-ray Computed Tomography Facility at UT Austin. They will be transported to the LacCore National Lacustrine Core Facility at U Minnesota, where they will be split, imaged, and scanned for several properties, including XRF data. The core will then be transported to the Rutgers University for sampling. The planning team is contemplating Phase Two options (e.g., the Middle to Lower Triassic marine-influenced section west of the Colorado Plateau (St. George, Utah) area or the Upper Triassic to Lower Jurassic sequence in the Comb Ridge area (Bluff, Utah)).

  13. Palaeogeography of Late Triassic red-beds in Singapore and the Indosinian Orogeny

    NASA Astrophysics Data System (ADS)

    Oliver, Grahame; Prave, Anthony

    2013-10-01

    A red-bed facies of the Upper Triassic Jurong Formation has been logged on Sentosa Island, Singapore. An overall coarsening and thickening-upward pattern is well developed. The lower part of the section is dominated by purple-red, massive to finely laminated illite-smectite-kaolin-rich mudstones containing thin, discontinuous lenses of fine sandstone marked by low-angle lamination and small ripples. One dinosaur-like foot print has been discovered in a loose block of red mudstone. It is concluded that this is a lacustrine sequence and it is proposed to name the lake, Lake Sentosa. The upper part of the sequence consists of flat-laminated to trough cross-bedded medium-grained sandstone and granule to cobble conglomerates alternating with purple-red mudstone. The mudstone-sandstone packages are arranged in decametre-scale coarsening-upward cycles. The channelling and decimetre-scale cross-bedding characterising the sandstone and conglomeratic beds is evidence for deposition by flashy fluvial flood processes, possibly feeding into the lake as a fresh water delta. One possible dinosaur trackway in granule size conglomerate has been located. Detrital zircon U-Pb ages vary from 2.7 Ba to 209 Ma with significant populations at ˜245 Ma and 220 Ma. These ages throw light on the timing of the Indosinian Orogeny. The molasse red-beds of the Jurong Formation were deposited in a half graben formed in the hangingwall of the Bukit Timah Fault when central Peninsular Malaysia went into extension following the climax of the Indosinian Orogeny in the Late Triassic.

  14. Permo-Triassic vertebrate extinctions: A program

    NASA Technical Reports Server (NTRS)

    Olson, E. C.

    1988-01-01

    Since the time of the Authors' study on this subject, a great deal of new information has become available. Concepts of the nature of extinctions have changed materially. The Authors' conclusion that a catastrophic event was not responsible for the extinction of vertebrates has modified to the extent that hypotheses involving either the impact of a massive extra-terrestrial body or volcanism provide plausible but not currently fully testable hypotheses. Stated changes resulted in a rapid decrease in organic diversity, as the ratio of origins of taxa to extinctions shifted from strongly positive to negative, with momentary equilibrium being reached at about the Permo-Triassic boundary. The proximate causes of the changes in the terrestrial biota appear to lie in two primary factors: (1) strong climatic changes (global mean temperatures, temperature ranges, humidity) and (2) susceptibility of the dominant vertebrates (large dicynodonts) and the glossopteris flora to disruption of the equlibrium of the world ecosystem. The following proximate causes have been proposed: (1) rhythmic fluctuations in solar radiation, (2) tectonic events as Pangea assembled, altering land-ocean relationships, patterns of wind and water circulation and continental physiography, (3) volcanism, and (4) changes subsequent to impacts of one or more massive extra terrestrial objects, bodies or comets. These hypotheses are discussed.

  15. Permian UPb (CA-TIMS) zircon ages from Australia and China: Constraining the time scale of environmental and biotic change

    Microsoft Academic Search

    S. W. Denyszyn; R. Mundil; I. Metcalfe; B. He

    2010-01-01

    In eastern Australia, the interconnected Bowen and Sydney Basins are filled with terrestrial sediments of late Paleozoic to early Mesozoic age. These sedimentary units record significant evolutionary events of eastern Gondwana during the time interval between two major mass extinctions (end Middle Permian and Permian-Triassic), and also provide lithological evidence for the Carboniferous-Permian Late Paleozoic Ice Age of southern Pangea,

  16. Permian–Triassic boundary magnetostratigraphy from the Southern Alps (Italy)

    Microsoft Academic Search

    Robert Scholger; Hermann J. Mauritsch; Rainer Brandner

    2000-01-01

    Palaeomagnetic investigations of Permian–Triassic boundary sections in the Dolomites provided a magnetostratigraphy for the uppermost part of the Permian Bellerophon Formation to the Lower Triassic Werfen Formation. Magnetite was the dominant magnetic component in most of the samples, while the presence of hematite was characteristic for the Tesero horizon, which is regarded as the immediate Permian–Triassic boundary layer. The palaeomagnetic

  17. TriassicJurassic boundary events: Problems, progress, possibilities 1. Problems

    E-print Network

    McRoberts, Christopher A.

    As for most geological period boundaries, the Triassic­Jurassic (T­J) transition, 200 million years agoEditorial Triassic­Jurassic boundary events: Problems, progress, possibilities 1. Problems to reconstruct past events, a physical record of their passing is essential. Here again the Triassic­Jurassic

  18. A multiple time scale solution for the Chapman mechanism

    SciTech Connect

    Chang, B.

    1994-06-01

    The rate equations representing the Chapman mechanism are solved analytically in the Multiple Time Scale Approximation by the exploitation of their stiffness. The widely different time scales of the reactions in the mechanism can be used to disentangle their effects on the solution. The reactions which bring oxygen into equilibrium with ozone are responsible for the overall stiffness, because their time scales are on the extreme ends of time scale spectrum for the reactions comprising the Chapman mechanism. Since catalytic cycles have similar equilibration reactions which may have time scales bordering the time scales of other reactions involving the catalysts, the method of multiple time scales can also be used to cured the stiffness in the rate equations governing these cycles. These analytical solutions may be incorporated into a numerical algorithm to improve its efficiency for the computation of the rate equations governing the chemistry of the atmosphere.

  19. Triassic actinopterygian fishes: the recovery after the end-Permian crisis.

    PubMed

    Tintori, Andrea; Hitij, Tomaž; Jiang, Dayong; Lombardo, Cristina; Sun, Zuoyu

    2014-08-01

    In the last 15 years, the discovery of several new actinopterygian fish faunas from the Early and Middle Triassic of the Tethys, cast new light on the timing, speed and range of their recovery after the end-Permian crisis. In addition to several new taxa having been described, the stratigraphical and geographical record of many others have been greatly extended. In fact, most of the new fossiliferous sites are in southern China, thus at the Eastern end of the Tethys, and furthermore a few are somewhat older (Chaohu, Panxian, Luoping) than the major classical Western Tethys sites (Monte San Giorgio). Following these new finds, it is possible to have a better definition of the Triassic recovery stages. Indeed, after a quite short phase till the end of the Smithian (Olenekian, Early Triassic) in which a rather consistent fauna was present all around the Pangea coasts, a major radiation occurred in the Early-Middle Anisian after the new Middle Triassic fish fauna already appeared in the late Early Triassic, thus occuring well before what was previously supposed from the Alps localities. Furthermore, the new assemblages from southern China point to an early broader differentiation among the basal neopterygians rather than in the 'subholosteans', the group that was then dominant in the Western Tethys since the Late Anisian. It stands that during the Norian a new basal neopterygian radiation gave rise to several new branches that dominated the remaining part of the Mesozoic. PMID:24148549

  20. Current Status of the Late Triassic and Early Jurassic APTS from Continental Sediments and Correlation with Standard Marine Stages

    NASA Astrophysics Data System (ADS)

    Kent, D. V.; Olsen, P. E.; Muttoni, G.

    2014-12-01

    A reproducible geomagnetic polarity template for the Late Triassic and earliest Jurassic continues to be that determined from ~5,000 meters of cored section in the Newark basin and ~2,500 meters of outcrop section in the Hartford basin, sampled at nominal ~20 kyr intervals according to a well-developed climate cyclicity that characterizes the lacustrine strata present in all but the fluviatile portions of the basins [Kent & Olsen, 1999, 2008 JGR]. The age model is based on the 405 kyr Milankovich climate cycle and pegging the sequence to high precision U-Pb dating of the Central Atlantic Magmatic Province (CAMP) at 201.6 to 200.9 Ma [Blackburn+2013 Science], the initiation of which is practically coincident with the end-Triassic extinction level (formerly set to 202 Ma) and within a climatic precession cycle after magnetochron E23r. The resulting astrochronostratigraphic polarity time scale (APTS) has 66 Poisson-distributed polarity intervals from chrons E8r (~225 Ma) to H27n (~199 Ma) with a constant sediment-accumulation rate extrapolation to chron E1r (~233 Ma). Magnetostratigraphic correlations from the most complete and usually the thickest Tethyan marine sections suggest that the Carnian/Norian boundary occurs within ~E7n [Channell+2003 PPP; Muttoni+2004 GSAB] at an APTS age of 227.5 Ma and for the Norian/Rhaetian boundary anywhere from E16n [Husing+2011 EPSL] at ~210.5 Ma to E20r [Maron+2014 Geology] at ~205.4 Ma depending on choice of conodont taxa, whereas the Hettangian/Sinemurian boundary can be placed at ~199.5 Ma within the marine equivalent of H25r [Husing+2014 EPSL]. These APTS ages are in substantive agreement with available high-precision dates in marine strata for the late Carnian [231 Ma: Furin+2006 Geology], latest Norian [205.5 Ma: Wotslaw+2014 Geology], and the boundaries of the Triassic/Jurassic [201.3 Ma: Guex+2012 PPP] and the Hettangian/Sinemurian [199.5 Ma: Schaltegger+2008 EPSL]. Carnian magnetostratigraphy needs to be improved but attempts to make a composite magnetostratigraphic sequence for the Late Triassic by merging disparate marine and non-marine records have not produced a clearer signal. The Newark-Hartford APTS already provides a framework for long-distance correlation and dating, for example, the timing of dinosaur dispersal across Pangea [Kent+2014 PNAS].

  1. BeiDou Navigation Satellite System and its time scales

    Microsoft Academic Search

    Chunhao Han; Yuanxi Yang; Zhiwu Cai

    2011-01-01

    The development and current status of BeiDou Navigation Satellite System are briefly introduced. The definition and realization of the system time scales are described in detail. The BeiDou system time (BDT) is an internal and continuous time scale without leap seconds. It is maintained by the time and frequency system of the master station. The frequency accuracy of BDT is

  2. Geologic Time Scale 2004 - why, how, and where next!

    Microsoft Academic Search

    Felix Gradstein; James Ogg

    2004-01-01

    A Geologic Time Scale (GTS2004) is presented that integrates currently available stratigraphic and geochronologic information. Key features of the new scale are outlined, how it was constructed, and how it can be improved Since Geologic Time Scale 1989 by Harland and his team, many developments have taken place: (1) Stratigraphic standardization through the work of the International Commission on Stratigraphy

  3. Time scaling of trajectories for cooperative multi-robot systems

    Microsoft Academic Search

    Seungbin B. Moon; Shaheen Ahmad

    1990-01-01

    The application of the time scaling method is extended to the multiple redundant robots in cooperative manipulation. The modification of the algorithm previously developed by the authors (Proc. 1990 IEEE Conf., Robotics and Automatio p.506-511, 1990) allows the use of the time scaling method without using the inverse of the Jacobian matrix. The trajectory scaling scheme described requires the use

  4. Optimum signal synthesis for time-scale estimation

    Microsoft Academic Search

    Ovarlez Jean

    1998-01-01

    In signal analysis, the joint estimation of the time-scale parameters which can affect a known signal (Doppler effect or scale effect, delay…) may be a problem of interest. An important result has shown that, even if the quality of the time delay estimation is classically given by the inverse spread of the signal spectral density, the quality of the scale

  5. Linking Response-Time Parameters onto a Common Scale

    ERIC Educational Resources Information Center

    van der Linden, Wim J.

    2010-01-01

    Although response times on test items are recorded on a natural scale, the scale for some of the parameters in the lognormal response-time model (van der Linden, 2006) is not fixed. As a result, when the model is used to periodically calibrate new items in a testing program, the parameter are not automatically mapped onto a common scale. Several…

  6. Constraints on the paleogeographic evolution of the North China Craton during the Late Triassic-Jurassic

    NASA Astrophysics Data System (ADS)

    Li, Hong-Yan; Huang, Xiao-Long

    2013-07-01

    This paper reports U-Pb-Hf isotopes of detrital zircons from Late Triassic-Jurassic sediments in the Ordos, Ningwu, and Jiyuan basins in the western-central North China Craton (NCC), with the aim of constraining the paleogeographic evolution of the NCC during the Late Triassic-Jurassic. The early Late Triassic samples have three groups of detrital zircons (238-363 Ma, 1.5-2.1 Ga, and 2.2-2.6 Ga), while the latest Late Triassic and Jurassic samples contain four groups of detrital zircons (154-397 Ma, 414-511 Ma, 1.6-2.0 Ga, and 2.2-2.6 Ga). The Precambrian zircons in the Late Triassic-Jurassic samples were sourced from the basement rocks and pre-Late Triassic sediments in the NCC. But the initial source for the 238-363 Ma zircons in the early Late Triassic samples is the Yinshan-Yanshan Orogenic Belt (YYOB), consistent with their negative zircon ?Hf(t) values (-24 to -2). For the latest Late Triassic and Jurassic samples, the initial source for the 414-511 Ma zircons with ?Hf(t) values of -18 to +9 is the Northern Qinling Orogen (NQO), and that for the 154-397 Ma zircons with ?Hf(t) values of -25 to +12 is the YYOB and the southeastern Central Asian Orogenic Belt (CAOB). In combination with previous data of late Paleozoic-Early Triassic sediments in the western-central NCC and Permian-Jurassic sediments in the eastern NCC, this study reveals two shifts in detrital source from the late Paleozoic to Jurassic. In the Late Permian-Early Triassic, the western-central NCC received detritus from the YYOB, southeastern CAOB and NQO. However, in the early Late Triassic, detritus from the CAOB and NQO were sparse in basins located in the western-central NCC, especially in the Yan'an area of the Ordos Basin. We interpret such a shift of detrital source as result of the uplift of the eastern NCC in the Late Triassic. In the latest Late Triassic-Jurassic, the southeastern CAOB and the NQO restarted to be source regions for basins in the western-central NCC, as well as for basins in the eastern NCC. The second shift in detrital source suggests elevation of the orogens surrounding the NCC and subsidence of the eastern NCC in the Jurassic, arguing against the presence of a paleo-plateau in the eastern NCC at that time. It would be subsidence rather than elevation of the eastern NCC in the Jurassic, due to roll-back of the subducted paleo-Pacific plate and consequent upwelling of asthenospheric mantle.

  7. The Late Triassic bivalve Monotis in accreted terranes of Alaska

    USGS Publications Warehouse

    Silberling, N.J.; Grant-Mackie, J. A.; Nichols, K.M.

    1997-01-01

    Late Triassic bivalves of the genus Monotis occur in at least 16 of the lithotectonic terranes and subterranes that together comprise nearly all of Alaska, and they also occur in the Upper Yukon region of Alaska where Triassic strata are regarded as representing non-accretionary North America. On the basis of collections made thus far, 14 kinds of Monotis that differ at the species or subspecies level can be recognized from alaska. These are grouped into the subgenera Monotis (Monotis), M. (Pacimonotis), M. (Entomonotis), and M. (Eomonotis). In places, Monotis shells of one kind or another occur in rock-forming abundance. On the basis of superpositional data from Alaska, as well as from elsewhere in North America and Far Eastern Russia, at least four distince biostratigraphic levels can be discriminated utilizing Monotis species. Different species of M. (Eomonotis) characterize two middle Norian levels, both probably within the supper middle Norian Columbianus Ammonite Zone. Two additional levels are recognized in the lower upper Norian Cordilleranus Ammonite Zone utilizing species of M. (Monotis) or M. (Entomonotis), both of which subgenera are restricted to the late Norian. An attached-floating mode of life is commonly attributed to Monotis; thus, these bivalves would have been pseudoplanktonic surface dwellers that were sensitive to surface-water temperature and paleolatitude. Distinctly different kinds of Monotis occur at different paleolatitudes along the Pacific and Arctic margins of the North American craton inboard of the accreted terranes. Comparison between thse craton-bound Monotis faunas and those of the Alaskan terranes in southern Alaska south of the Denali fault were paleoequatorial in latitude during Late Triassic time. Among these terranes, the Alexander terrane was possibly in the southern hemisphere at that time. Terranes of northern Alaska, on the other hand, represent middle, possibly high-middle, northern paleolatitudes.

  8. The "terminal Triassic catastrophic extinction event" in perspective: a review of carboniferous through Early Jurassic terrestrial vertebrate extinction patterns

    USGS Publications Warehouse

    Weems, R.E.

    1992-01-01

    A catastrophic terminal Triassic extinction event among terrestrial vertebrates is not supported by available evidence. The current model for such an extinction is based on at least eight weak or untenable assumptions: (1) a terminal Triassic extinction-inducing asteroid impact occurred, (2) a terminal Triassic synchronous mass extinction of terrestrial vertebrates occurred, (3) a concurrent terminal Triassic marine extinction occurred, (4) all terrestrial vertebrate families have similar diversities and ecologies, (5) changes in familial diversity can be gauged accurately from the known fossil record, (6) extinction of families can be compared through time without normalizing for changes in familial diversity through time, (7) extinction rates can be compared without normalizing for differing lengths of geologic stages, and (8) catastrophic mass extinctions do not select for small size. These assumptions have resulted in unsupportable and (or) erroneous conclusions. Carboniferous through Early Jurassic terrestrial vertebrate families mostly have evolution and extinction patterns unlike the vertebrate evolution and extinction patterns during the terminal Cretaceous event. Only the Serpukhovian (mid Carboniferous) extinction event shows strong analogy to the terminal Cretaceous event. Available data suggest no terminal Triassic extinction anomaly, but rather a prolonged and nearly steady decline in the global terrestrial vertebrate extinction rate throughout the Triassic and earliest Jurassic. ?? 1992.

  9. On the Uncertainty of the Annular Mode Time Scale

    NASA Astrophysics Data System (ADS)

    Kim, Junsu; Reichler, Thomas

    2015-04-01

    The proper simulation of the annular mode (AM) time scale may be regarded as an important benchmark for climate models. Previous research demonstrated that climate models systematically overestimate this time scale. As suggested by the fluctuation-dissipation theorem, this may imply that models are overly sensitive to external forcings. Previous research also made it clear that calculating the AM time scale is a slowly converging process, necessitating relatively long time series and casting doubts on the usefulness of the historical reanalysis record to constrain climate models in terms of the AM time scale. Here, we use a 4000-year-long control simulation with the GFDL climate model CM2.1 to study the effects of internal atmospheric variability on the stability of the AM time scale. In particular, we ask whether a model's AM time scale and climate sensitivity can be constrained from the 50-year-long reanalysis record. We find that internal variability attaches large uncertainty to the AM time scale when diagnosed from decadal records. Even under fixed forcing conditions, at least 100 years of data are required in order to keep the uncertainty in the AM time scale of the Northern Hemisphere to 10%; over the Southern Hemisphere the required length increases to 200 years. If nature's AM time scale is similarly variable, there is no guarantee that the historical reanalysis record is a fully representative target for model evaluation. We further use the model simulation to investigate the dynamical coupling between the stratosphere and the troposphere from the perspective of the AM time scale. Over the Northern Hemisphere we find only weak indication for influences from stratosphere-troposphere coupling on the AM time scale. The situation is very different over the Southern Hemisphere, where we find robust connections between the AM time scale in the stratosphere and that in the troposphere, confirming and extending earlier results of influences of stratospheric variability on the troposphere.

  10. Controllability and Observability of Linear Time-Varying Impulsive Systems on Time Scales

    NASA Astrophysics Data System (ADS)

    Zhang, Kexue; Liu, Xinzhi

    2011-11-01

    This paper studies the problems of controllability and observability of a general linear time-varying impulsive control systems on time scales. By proposing a formula of variation of parameters for this type of systems on time scales, several necessary and sufficient criteria on controllability and observability of the impulsive control system on time scales are established. It is shown that the classical results about controllability and observability of linear continuous impulsive systems can be generalized to the impulsive systems on time scales.

  11. Biochronology of Triassic bivalves CHRISTOPHER A. MCROBERTS

    E-print Network

    McRoberts, Christopher A.

    , these bivalves occur in a wide variety of marine facies and water depths, but are most notable for their thick in or near oxygen deficient settings. A new biochronological zonation for bivalves is presented bivalve zonations have been provided for specific regions and or limited portions of the Triassic

  12. Early ornithischian dinosaurs: the Triassic record

    Microsoft Academic Search

    Randall B. Irmis; William G. Parker; Sterling J. Nesbitt; Jun Liu

    2007-01-01

    Ornithischian dinosaurs are one of the most taxonomically diverse dinosaur clades during the Mesozoic, yet their origin and early diversification remain virtually unknown. In recent years, several new Triassic ornithischian taxa have been proposed, mostly based upon isolated teeth. New discoveries of skeletal material of some of these tooth taxa indicate that these teeth can no longer be assigned to

  13. A gigantic nothosaur (Reptilia: Sauropterygia) from the Middle Triassic of SW China and its implication for the Triassic biotic recovery.

    PubMed

    Liu, Jun; Hu, Shi-Xue; Rieppel, Olivier; Jiang, Da-Yong; Benton, Michael J; Kelley, Neil P; Aitchison, Jonathan C; Zhou, Chang-Yong; Wen, Wen; Huang, Jin-Yuan; Xie, Tao; Lv, Tao

    2014-01-01

    The presence of gigantic apex predators in the eastern Panthalassic and western Tethyan oceans suggests that complex ecosystems in the sea had become re-established in these regions at least by the early Middle Triassic, after the Permian-Triassic mass extinction (PTME). However, it is not clear whether oceanic ecosystem recovery from the PTME was globally synchronous because of the apparent lack of such predators in the eastern Tethyan/western Panthalassic region prior to the Late Triassic. Here we report a gigantic nothosaur from the lower Middle Triassic of Luoping in southwest China (eastern Tethyan ocean), which possesses the largest known lower jaw among Triassic sauropterygians. Phylogenetic analysis suggests parallel evolution of gigantism in Triassic sauropterygians. Discovery of this gigantic apex predator, together with associated diverse marine reptiles and the complex food web, indicates global recovery of shallow marine ecosystems from PTME by the early Middle Triassic. PMID:25429609

  14. A gigantic nothosaur (Reptilia: Sauropterygia) from the Middle Triassic of SW China and its implication for the Triassic biotic recovery

    PubMed Central

    Liu, Jun; Hu, Shi-xue; Rieppel, Olivier; Jiang, Da-yong; Benton, Michael J.; Kelley, Neil P.; Aitchison, Jonathan C.; Zhou, Chang-yong; Wen, Wen; Huang, Jin-yuan; Xie, Tao; Lv, Tao

    2014-01-01

    The presence of gigantic apex predators in the eastern Panthalassic and western Tethyan oceans suggests that complex ecosystems in the sea had become re-established in these regions at least by the early Middle Triassic, after the Permian-Triassic mass extinction (PTME). However, it is not clear whether oceanic ecosystem recovery from the PTME was globally synchronous because of the apparent lack of such predators in the eastern Tethyan/western Panthalassic region prior to the Late Triassic. Here we report a gigantic nothosaur from the lower Middle Triassic of Luoping in southwest China (eastern Tethyan ocean), which possesses the largest known lower jaw among Triassic sauropterygians. Phylogenetic analysis suggests parallel evolution of gigantism in Triassic sauropterygians. Discovery of this gigantic apex predator, together with associated diverse marine reptiles and the complex food web, indicates global recovery of shallow marine ecosystems from PTME by the early Middle Triassic. PMID:25429609

  15. Palynological assemblages of non-marine rocks at the Permian Triassic boundary, western Guizhou and eastern Yunnan, South China

    NASA Astrophysics Data System (ADS)

    Peng, Yuanqiao; Yu, Jianxin; Gao, Yongqun; Yang, Fengqing

    2006-12-01

    Marine and non-marine facies of the Permian-Triassic boundary stratigraphic set (PTBST) are well developed in South China. Palynological assemblages enable subdivision and correlation of the Permian-Triassic boundary (PTB) rocks. Three palynological assemblages are recognized across the PTBST in two terrestrial PTB sections in western Guizhou and eastern Yunnan, South China. Assemblage 1 (Xuanwei Formation) is a Late Permian palynological assemblage dominated by ferns and pteridosperms, with minor gymnosperms. Most taxa are typical long-ranging Paleozoic forms, but the appearance of Lueckisporites confirms a Late Permian age for this assemblage. Assemblage 2 (PTBST) is marked by an abrupt decrease in palynomorph abundance and diversity, and thriving fungal/algal(?) spores. Assemblage 2 is still dominated by ferns and pteridosperms, with a few gymnosperms, but is characterized by a mixed palynoflora containing both Late Permian and Early Triassic elements. Most taxa are typical Late Permian ones also found in Assemblage 1, however, some taxa of Early Triassic aspect, e.g. Lundbladispora and Taeniaesporites, appeared for the first time. In Assemblage 3 (top Xuanwei Formation and Kayitou Formation), the proportion of gymnosperm pollen increases rapidly, exceeding that of ferns and pteridosperms, but the abundance of palynomorphs is still low. Typical Early Triassic taxa (such as Lundbladispora, Aratrisporites and Taeniaesporites) are present in greater abundance and confirms an Early Triassic age for this assemblage.

  16. How was the Triassic Songpan-Ganzi basin filled? A provenance study

    USGS Publications Warehouse

    Enkelmann, E.; Weislogel, A.; Ratschbacher, L.; Eide, E.; Renno, A.; Wooden, J.

    2007-01-01

    The Triassic Songpan-Ganzi complex comprises >200,000 km2 of 5-15 km thick turbiditic sediments. Although surrounded by several magmatic and orogenic belts, the Triassic high- and ultrahigh-pressure Qinling-Tongbai-Hong'an-Dabie (QTHD) orogen, located several hundred kilometers to the east, was proposed as its major source. Middle to Late Triassic samples from the northern and southern Songpan-Ganzi complex, studied using detrital white mica 40Ar/39Ar ages, Si-in-white mica content, and detrital zircon U/Pb ages, suggest that the northern Songpan-Ganzi deposystem obtained detritus from the north: the north China block, east Kunlun, northern Qaidam, Qilian, and western Qinling; the southern Songpan-Ganzi deposystem was supplied from the northeasterly located Paleozoic QTHD area throughout the Ladinian and received detritus from the Triassic Hong'an-Dabie orogen during the Carnian, indicative of exhumation of the orogen at that time. The QTHD orogen fed the Norian samples in the southeastern southern Songpan-Ganzi deposystem, signifying long drainage channels along the western margin of the south China block. An additional supply from the Emeishan magmatic province and/or the Yidun arc is suggested by the paucity of white mica in the southern Songpan-Ganzi deposystem. Mica ages of Rhaetian sediments from the northwestern Sichuan basin best correlate with those of the Triassic QTHD orogen. Our Si-in-white mica data demonstrate that the high- and ultrahigh-pressure rocks of the Hong'an-Dabie Shan were not exposed in the Middle to Late Triassic. Copyright 2007 by the American Geophysical Union.

  17. Floral changes across the Triassic\\/Jurassic boundary linked to flood basalt volcanism

    Microsoft Academic Search

    B. van de Schootbrugge; T. M. Quan; S. Lindström; W. Püttmann; C. Heunisch; J. Pross; J. Fiebig; R. Petschick; H.-G. Röhling; S. Richoz; Y. Rosenthal; P. G. Falkowski

    2009-01-01

    One of the five largest mass extinctions of the past 600million years occurred at the boundary of the Triassic and Jurassic periods, 201.6million years ago. The loss of marine biodiversity at the time has been linked to extreme greenhouse warming, triggered by the release of carbon dioxide from flood basalt volcanism in the central Atlantic Ocean. In contrast, the biotic

  18. Late Precambrian to Triassic history of the East European Craton: dynamics of sedimentary basin evolution

    Microsoft Academic Search

    A. M. Nikishin; P. A. Ziegler; R. A. Stephenson; S. A. P. L. Cloetingh; A. V. Furne; P. A. Fokin; A. V. Ershov; S. N. Boloytov; M. V. Korotaev; A. S. Alekseev; V. I. Gorbachev; E. V. Shipilov; A. C. Lankreijer; E. Yu. Bembinova; I. V. Shalimov

    1996-01-01

    During its Riphean to Palaeozoic evolution, the East European Craton was affected by rift phases during Early, Middle and Late Riphean, early Vendian, early Palaeozoic, Early Devonian and Middle-Late Devonian times and again at the transition from the Carboniferous to the Permian and the Permian to the Triassic. These main rifting cycles were separated by phases of intraplate compressional tectonics

  19. Slow-time acceleration for modeling multiple-time-scale problems

    NASA Astrophysics Data System (ADS)

    Haselbacher, A.; Najjar, F. M.; Massa, L.; Moser, R. D.

    2010-01-01

    The numerical simulation of a system exhibiting a broad range of time scales can be very expensive because the time discretization will in general need to resolve the smallest time scale, and the simulation will have to extend over many times the longest time scale. However, it is common that not all the time scales are of interest for a particular problem. When the long time scales are of primary interest, a number of techniques are available to eliminate the unwanted short time scales from consideration. When the short time scales are of primary interest, a technique for mitigating the consequences of anomalously long time scales is needed. The "slow-time acceleration" technique presented here has been developed to address this problem. In the slow-time acceleration technique, a modified evolution equation is developed in which the longest time scale is much shorter than that of the original system, and which has the same multi-time scale asymptotic structure as the original system. As an example, this approach is applied to the numerical simulation of solid-propellant rockets in which the long time scale is associated with the regression of the burning propellant.

  20. Triassic terrigeneous deposits of Western Chukotka: sedimentation, mineral composition, deformations (NE Russia)

    Microsoft Academic Search

    M. I. Tuchkova; G. Y. Bondarenko; E. L. Miller; S. M. Katkov

    2004-01-01

    Chukotka's Triassic terrigeneous deposits form three different complexes: Lower-Middle Triassic complex, Upper Triassic Karnian complex and Upper Triassic Norian complex. The studied part of western Chukotka is composed of variably deformed, folded and cleaved rhythmic deposits. All the complexes are represented by rhythmic intercalation of sandstones, siltstones and mudstones. Unfortunately, macrofaunas are not numerous in the Triassic deposits, and in

  1. SOME MULTIPLE-TIME-SCALE PROBLEMS IN MOLECULAR DYNAMICS

    Microsoft Academic Search

    DUS ANKA; JANEZ IC

    2002-01-01

    Many physical problems, paricularly in chemical and biological systems, involve processes that occur over widely varying time scales. Such problems have motivated the development of new methods for treating multiple- time-scale problems in molecular dynamics (MD). Methods have been developed for determining the vibrational frequencies and normal modes of large systems in full and reduced conformational space. A method is

  2. Time distribution and loss of scaling in granular flow

    Microsoft Academic Search

    B. Tadic

    1999-01-01

    :   Two cellular automata models with directed mass flow and internal time scales are studied by numerical simulations. Relaxation\\u000a rules are a combination of probabilistic critical height (probability of toppling p) and deterministic critical slope processes with internal correlation time tc equal to the avalanche lifetime, in model A, and ,in model B. In both cases nonuniversal scaling properties of

  3. Singular perturbation and time scale approaches in discrete control systems

    NASA Technical Reports Server (NTRS)

    Naidu, D. S.; Price, D. B.

    1988-01-01

    After considering a singularly perturbed discrete control system, a singular perturbation approach is used to obtain outer and correction subsystems. A time scale approach is then applied via block diagonalization transformations to decouple the system into slow and fast subsystems. To a zeroth-order approximation, the singular perturbation and time-scale approaches are found to yield equivalent results.

  4. Triassic/Jurassic faulting patterns of Conecuh Ridge, southwest Alabama

    SciTech Connect

    Hutley, J.K.

    1985-02-01

    Two major fault systems influenced Jurassic structure and deposition on the Conecuh Ridge, southwest Alabama. Identification and dating of these fault systems are based on seismic-stratigraphic interpretation of a 7-township grid in Monroe and Conecuh Counties. Relative time of faulting is determined by fault geometry and by formation isopachs and isochrons. Smackover and Norphlet Formations, both Late Jurassic in age, are mappable seismic reflectors and are thus reliable for seismicstratigraphic dating. The earlier of the 2 fault systems is a series of horsts and grabens that trends northeast-southwest and is Late Triassic to Early Jurassic in age. The system formed in response to tensional stress associated with the opening of the Atlantic Ocean. The resulting topography was a series of northeast-southwest-trending ridges. Upper Triassic Eagle Mills and Jurassic Werner Formations were deposited in the grabens. The later fault system is also a series of horsts and grabens trending perpendicular to the first. This system was caused by tensional stress related to a pulse in the opening of the Gulf of Mexico. Faulting began in Early Jurassic and continued into Late Jurassic, becoming progressively younger basinward. At the basin margin, faulting produced a very irregular shoreline. Submerged horst blocks became centers for shoaling or carbonate buildups. Today, these blocks are exploration targets in southwest Alabama.

  5. Integrated Sr isotope variations and global environmental changes through the Late Permian to early Late Triassic

    NASA Astrophysics Data System (ADS)

    Song, Haijun; Wignall, Paul B.; Tong, Jinnan; Song, Huyue; Chen, Jing; Chu, Daoliang; Tian, Li; Luo, Mao; Zong, Keqing; Chen, Yanlong; Lai, Xulong; Zhang, Kexin; Wang, Hongmei

    2015-08-01

    New 87Sr/86Sr data based on 127 well-preserved and well-dated conodont samples from South China were measured using a new technique (LA-MC-ICPMS) based on single conodont albid crown analysis. These reveal a spectacular climb in seawater 87Sr/86Sr ratios during the Early Triassic that was the most rapid of the Phanerozoic. The rapid increase began in Bed 25 of the Meishan section (GSSP of the Permian-Triassic boundary, PTB), and coincided closely with the latest Permian extinction. Modeling results indicate that the accelerated rise of 87Sr/86Sr ratios can be ascribed to a rapid increase (>2.8×) of riverine flux of Sr caused by intensified weathering. This phenomenon could in turn be related to an intensification of warming-driven runoff and vegetation die-off. Continued rise of 87Sr/86Sr ratios in the Early Triassic indicates that continental weathering rates were enhanced >1.9 times compared to those of the Late Permian. Continental weathering rates began to decline in the middle-late Spathian, which may have played a role in the decrease of oceanic anoxia and recovery of marine benthos. The 87Sr/86Sr values decline gradually into the Middle Triassic to an equilibrium values around 1.2 times those of the Late Permian level, suggesting that vegetation coverage did not attain pre-extinction levels thereby allowing higher runoff.

  6. The drift Hystory of Iran from the Ordovician to the Triassic

    NASA Astrophysics Data System (ADS)

    Muttoni, G.; Mattei, M.; Marco, B.; Zanchi, A.; Gaetani, M.; Berra, F.; Kent, D. V.; Angiolini, L.

    2009-05-01

    New Late Ordovician, Permian, and Triassic paleomagnetic data from Iran are presented. These data, in conjunction with data from the literature, provide insights on the drift history of Iran as part of Cimmeria during the Ordovician-Triassic. A robust agreement of paleomagnetic poles of Iran and West Gondwana is observed for the Late Ordovician-earliest Carboniferous, indicating that Iran was part of Gondwana during that time. Data for the Late Permian-early Early Triassic indicate that Iran resided on subequatorial palaeolatitudes, clearly disengaged from the parental Gondwanan margin in the southern hemisphere as the result of the opening of the Neotethys Ocean along the eastern margin of Gondwana during the Permian. Since possibly the late Early Triassic, Iran was located in the northern hemisphere close to the Eurasian margin. This northward drift brought Iran to cover much of the Paleotethys in ~35 Myr at an average plate speed of ~7-8 cm/yr. As a novel conclusion, we find that timing, rates, and geometry of Cimmerian tectonics are broadly compatible with the transformation of Pangea from an Irvingian B to a Wegenerian A-type configuration with Neo-Tethyan opening taking place contemporaneously essentially in the Permian.

  7. Zircon U-Pb geochronology links the end-Triassic extinction with the Central Atlantic Magmatic Province.

    PubMed

    Blackburn, Terrence J; Olsen, Paul E; Bowring, Samuel A; McLean, Noah M; Kent, Dennis V; Puffer, John; McHone, Greg; Rasbury, E Troy; Et-Touhami, Mohammed

    2013-05-24

    The end-Triassic extinction is characterized by major losses in both terrestrial and marine diversity, setting the stage for dinosaurs to dominate Earth for the next 136 million years. Despite the approximate coincidence between this extinction and flood basalt volcanism, existing geochronologic dates have insufficient resolution to confirm eruptive rates required to induce major climate perturbations. Here, we present new zircon uranium-lead (U-Pb) geochronologic constraints on the age and duration of flood basalt volcanism within the Central Atlantic Magmatic Province. This chronology demonstrates synchroneity between the earliest volcanism and extinction, tests and corroborates the existing astrochronologic time scale, and shows that the release of magma and associated atmospheric flux occurred in four pulses over about 600,000 years, indicating expansive volcanism even as the biologic recovery was under way. PMID:23519213

  8. Allometric scaling and maximum efficiency in physiological eigen time

    PubMed Central

    Andresen, Bjarne; Shiner, J. S.; Uehlinger, Dominik E.

    2002-01-01

    General optimization results from physics indicate that maximum efficiency of a process, in the sense of minimum overall entropy production, is achieved when the rate of entropy production is constant over time, however not in ordinary clock time but on an, in general varying, “eigen timescale, intrinsic to the system. We identify the eigen time of a biological system with “physiological time,” which generally scales with the 1/4 power of body mass, M1/4, over a vast range of species. Since it is equally well established that metabolic rate scales as M3/4, it follows that organisms produce entropy at the same intrinsic rate, fulfilling a necessary condition for maximum efficiency, and are all, furthermore, equally efficient on the physiological eigen time scale. PMID:11959910

  9. Characteristic Variability Time Scales of Long Gamma-Ray Bursts

    E-print Network

    R. F. Shen; L. M. Song

    2003-06-07

    We determined the characteristic variability time scales (\\Delta t_p) of 410 bright and long GRBs, by locating the peaks of their Power Density Spectra, defined and calculated in the time domain. We found that the averaged variability time scale decreases with the peak flux. This is consistent with the time-dilation effect expected for the cosmological origin of GRBs. We also found that the occurrence distribution of the characteristic variability time scale shows bimodality, which might be interpreted as that the long GRB sample is composed of two sub-classes with different variability time scales. However, we found no difference for some other characteristics of these two sub-classes.

  10. Limitations of the Method of Multiple-Time-Scales

    Microsoft Academic Search

    Peter B. Kahn; Yair Zarmi

    2002-01-01

    In the Method of Multiple-Time-Scales (MMTS), the introduction of independent time scales and the elimination of secular terms in the fast time variable, T0 = t, lead to the well-known solvability conditions. Starting from first order, free terms (solutions of the unperturbed equations) emerge in every order in the expansion of the approximate solution. In orders higher than first, the

  11. On the stability of multiple time-scale systems

    Microsoft Academic Search

    EYAD H. ABED

    1986-01-01

    The stability of time-invariant multiparameter singular perturbation problems is considered and the implications of two time-scale stability results for multiple time-scale systems are clarified. An example shows that the asymptotic stability of a multiparameter singular perturbation problem under the ‘bounded mutual ratios’ assumption for arbitrary bounds on the ratios of the small parameters does not imply asymptotic stability under the

  12. Scaling analysis of multi-variate intermittent time series

    NASA Astrophysics Data System (ADS)

    Kitt, Robert; Kalda, Jaan

    2005-08-01

    The scaling properties of the time series of asset prices and trading volumes of stock markets are analysed. It is shown that similar to the asset prices, the trading volume data obey multi-scaling length-distribution of low-variability periods. In the case of asset prices, such scaling behaviour can be used for risk forecasts: the probability of observing next day a large price movement is (super-universally) inversely proportional to the length of the ongoing low-variability period. Finally, a method is devised for a multi-factor scaling analysis. We apply the simplest, two-factor model to equity index and trading volume time series.

  13. Conodont paleoecology of Lower Triassic Thaynes Formation

    SciTech Connect

    Carr, T.R.

    1983-03-01

    The Lower Triassic (Smithian) Thaynes Formation represents a broad spectrum of paleoenvironments. Samples arranged along a generalized depth-salinity environmental gradient from tidal flats to a relatively deep, commonly dysaerobic, basin yielded a conodont fauna of 30 form elements. Association and similarity analysis were used to group the conodont elements into eight conodont entities, reflecting both biologic association (multielement apparatuses) and ecologic association (biofacies). Simple chi-square tests and discriminant analyses, using the eight conodont entities, and indicate presence of three distinctive conodont biofacies related to the generalized environmental gradient. The restricted inner shelf biotope was characterized by a conodont fauna dominated by Parachirognathus. The outer shelf biotope was distinguished by a diverse conodont fauna including the distinctive form Furnishius. The biotope farthest offshore consists of a low diversity conodont fauna composed primarily of species of Neogondolella. Some early Triassic conodonts such as Neospathodus and Ellisonia triassica are ubiquitous, and provide the foundation for a inter-basinal conodont zonation. Early Triassic conodont biotopes can be arranged along a generalized environmental gradient that probably reflects changes in hydrographic factors (e.g., salinity, temperature, and energy) which affected the distribution of conodonts.

  14. On time scale invariance of random walks in confined space.

    PubMed

    Bearup, Daniel; Petrovskii, Sergei

    2015-02-21

    Animal movement is often modelled on an individual level using simulated random walks. In such applications it is preferable that the properties of these random walks remain consistent when the choice of time is changed (time scale invariance). While this property is well understood in unbounded space, it has not been studied in detail for random walks in a confined domain. In this work we undertake an investigation of time scale invariance of the drift and diffusion rates of Brownian random walks subject to one of four simple boundary conditions. We find that time scale invariance is lost when the boundary condition is non-conservative, that is when movement (or individuals) is discarded due to boundary encounters. Where possible analytical results are used to describe the limits of the time scaling process, numerical results are then used to characterise the intermediate behaviour. PMID:25481837

  15. Time Scaling of Chaotic Systems: Application to Secure Communications

    E-print Network

    Donatello Materassi; Michele Basso

    2007-10-25

    The paper deals with time-scaling transformations of dynamical systems. Such scaling functions operate a change of coordinates on the time axis of the system trajectories preserving its phase portrait. Exploiting this property, a chaos encryption technique to transmit a binary signal through an analog channel is proposed. The scheme is based on a suitable time-scaling function which plays the role of a private key. The encoded transmitted signal is proved to resist known decryption attacks offering a secure and reliable communication.

  16. Myosin Dynamics on the Millisecond Time Scale

    PubMed Central

    Burghardt, Thomas P.; Yan Hu, Jimmy; Ajtai, Katalin

    2007-01-01

    Myosin is a motor protein associating with actin and ATP. It translates along actin filaments against a force by transduction of free energy liberated with ATP hydrolysis. Various myosin crystal structures define time points during ATPase showing the protein undergoes large conformation change during transduction over a cycle with ?10 milliseconds periodicity. The protein conformation trajectory between two intermediates in the cycle is surmised by non-equilibrium Monte Carlo simulation utilizing free energy minimization. The trajectory shows myosin transduction of free energy to mechanical work giving evidence for: (i) a causal relationship between product release and work production in the native isoform that is correctly disrupted in a chemically modified protein, (ii) the molecular basis of ATP sensitive tryptophan fluorescence enhancement and acrylamide quenching, (iii) an actin binding site peptide containing the free energy barrier to ATPase product release defining the rate limiting step and, (iv) a scenario for actin-activation of myosin ATPase. PMID:17913331

  17. Myosin dynamics on the millisecond time scale.

    PubMed

    Burghardt, Thomas P; Hu, Jimmy Yan; Ajtai, Katalin

    2007-12-01

    Myosin is a motor protein associating with actin and ATP. It translates along actin filaments against a force by transduction of free energy liberated with ATP hydrolysis. Various myosin crystal structures define time points during ATPase showing the protein undergoes large conformation change during transduction over a cycle with approximately 10 ms periodicity. The protein conformation trajectory between two intermediates in the cycle is surmised by non-equilibrium Monte Carlo simulation utilizing free-energy minimization. The trajectory shows myosin transduction of free energy to mechanical work giving evidence for: (i) a causal relationship between product release and work production in the native isoform that is correctly disrupted in a chemically modified protein, (ii) the molecular basis of ATP-sensitive tryptophan fluorescence enhancement and acrylamide quenching, (iii) an actin-binding site peptide containing the free-energy barrier to ATPase product release defining the rate limiting step and, (iv) a scenario for actin-activation of myosin ATPase. PMID:17913331

  18. Aftermath of the Permian-Triassic mass extinction event: Paleoecology of Lower Triassic carbonates in the western USA

    Microsoft Academic Search

    Jennifer K. Schubert; David J. Bottjer

    1995-01-01

    Paleoecologic study of invertebrate faunas from three successive Early Triassic seaways reveals that biotic recovery from the end-Permian mass extinction event was slow, and that full recovery did not occur until after the Early Triassic. Simple, cosmopolitan, opportunistic generalists, and low-diversity, low-complexity paleocommunities were characteristic of the entire Early Triassic in the Western USA. An increase in guild and taxonomic

  19. Macropredatory ichthyosaur from the Middle Triassic and the origin of modern trophic networks

    PubMed Central

    Fröbisch, Nadia B.; Fröbisch, Jörg; Sander, P. Martin; Schmitz, Lars; Rieppel, Olivier

    2013-01-01

    The biotic recovery from Earth’s most severe extinction event at the Permian-Triassic boundary largely reestablished the preextinction structure of marine trophic networks, with marine reptiles assuming the predator roles. However, the highest trophic level of today's marine ecosystems, i.e., macropredatory tetrapods that forage on prey of similar size to their own, was thus far lacking in the Paleozoic and early Mesozoic. Here we report a top-tier tetrapod predator, a very large (>8.6 m) ichthyosaur from the early Middle Triassic (244 Ma), of Nevada. This ichthyosaur had a massive skull and large labiolingually flattened teeth with two cutting edges indicative of a macropredatory feeding style. Its presence documents the rapid evolution of modern marine ecosystems in the Triassic where the same level of complexity as observed in today’s marine ecosystems is reached within 8 My after the Permian-Triassic mass extinction and within 4 My of the time reptiles first invaded the sea. This find also indicates that the biotic recovery in the marine realm may have occurred faster compared with terrestrial ecosystems, where the first apex predators may not have evolved before the Carnian. PMID:23297200

  20. Macropredatory ichthyosaur from the Middle Triassic and the origin of modern trophic networks.

    PubMed

    Fröbisch, Nadia B; Fröbisch, Jörg; Sander, P Martin; Schmitz, Lars; Rieppel, Olivier

    2013-01-22

    The biotic recovery from Earth's most severe extinction event at the Permian-Triassic boundary largely reestablished the preextinction structure of marine trophic networks, with marine reptiles assuming the predator roles. However, the highest trophic level of today's marine ecosystems, i.e., macropredatory tetrapods that forage on prey of similar size to their own, was thus far lacking in the Paleozoic and early Mesozoic. Here we report a top-tier tetrapod predator, a very large (>8.6 m) ichthyosaur from the early Middle Triassic (244 Ma), of Nevada. This ichthyosaur had a massive skull and large labiolingually flattened teeth with two cutting edges indicative of a macropredatory feeding style. Its presence documents the rapid evolution of modern marine ecosystems in the Triassic where the same level of complexity as observed in today's marine ecosystems is reached within 8 My after the Permian-Triassic mass extinction and within 4 My of the time reptiles first invaded the sea. This find also indicates that the biotic recovery in the marine realm may have occurred faster compared with terrestrial ecosystems, where the first apex predators may not have evolved before the Carnian. PMID:23297200

  1. Integrated Record of Terrestrial Biotic Change from the Upper Triassic Chinle Formation of northern New Mexico

    NASA Astrophysics Data System (ADS)

    Irmis, R. B.; Lindström, S.; Dunlavey, M.; Whiteside, J. H.

    2010-12-01

    The Triassic Period was an interval of major biotic and environmental changes sandwiched between two major mass extinctions. During the Late Triassic (235-201.3 Ma), dinosaurs originated and diversified across Pangaea, and several major extant vertebrate groups also appeared for the first time. Unfortunately, few detailed stratigraphically-precise local-regional paleontological records exist for continental Triassic strata, which hinders any attempt to understand the tempo and mode of biotic change through the Late Triassic. We present a new stratigraphically well-constrained fossil vertebrate and palynomorph record (10-15 Ma in duration) from the upper Chinle Formation of the Chama Basin, northern New Mexico, an area that is famous for preserving one of the best records of early dinosaurs in North America. Our data indicate that vertebrate faunas were generally stable, experiencing only one identifiable species turnover event. Dinosaurs, although relatively diverse, were never abundant components of the fauna. Contemporaneous palynological records indicate that floral composition fluctuated considerably. The drought-tolerant conifer pollen Enzonalasporites and other gymnosperms such as Alisporites and Protodiploxypinus dominate most palynofloral assemblages, but there is a distinct increase in fern spore abundance near the top of the section. In combination with evidence of variability from organic carbon stable isotopes, these data indicate that the vertebrate fauna, including early dinosaurs, remained stable over millions of years despite living within a dynamic ecosystem associated with rapidly changing environmental conditions.

  2. Liquidity spillover in international stock markets through distinct time scales.

    PubMed

    Righi, Marcelo Brutti; Vieira, Kelmara Mendes

    2014-01-01

    This paper identifies liquidity spillovers through different time scales based on a wavelet multiscaling method. We decompose daily data from U.S., British, Brazilian and Hong Kong stock markets indices in order to calculate the scale correlation between their illiquidities. The sample is divided in order to consider non-crisis, sub-prime crisis and Eurozone crisis. We find that there are changes in correlations of distinct scales and different periods. Association in finest scales is smaller than in coarse scales. There is a rise on associations in periods of crisis. In frequencies, there is predominance for significant distinctions involving the coarsest scale, while for crises periods there is predominance for distinctions on the finest scale. PMID:24465918

  3. Global Secular Variation from Satellite to Millennia Time Scales

    NASA Astrophysics Data System (ADS)

    Korte, M.

    2003-12-01

    Secular variation can be studied on a large range of time scales from direct and indirect measurements of the geomagnetic field. Questions like minimum period and spatial scale of variations originating in the core are investigated with observatory and satellite data. Variations of external origin and mantle filtering are major impediments here. Indirect records of the geomagnetic field from archeo- and paleomagnetic studies provide time series long enough to investigate full periods of secular variation and the underlying core dynamics. While recently first continuous global models on the millennia scale have been developed, dating uncertainties in the individual time series and sparse data coverage challenge their reliability. Here an overview over secular variation features and their implications as determined from global models on decade to millennia time scales is given.

  4. Diffusion Time-Scale of Porous Pressure-Sensitive Paint

    NASA Technical Reports Server (NTRS)

    Liu, Tianshu; Teduka, Norikazu; Kameda, Masaharu; Asai, Keisuke

    2001-01-01

    Pressure-sensitive paint (PSP) is an optical pressure sensor that utilizes the oxygen quenching of luminescence. PSP measurements in unsteady aerodynamic flows require fast time response of the paint. There are two characteristic time-scales that are related to the time response of PSP. One is the luminescent lifetime representing an intrinsic physical limit for the achievable temporal resolution of PSP. Another is the time-scale of oxygen diffusion across the PSP layer. When the time-scale of oxygen diffusion is much larger than the luminescent lifetime, the time response of PSP is controlled by oxygen diffusion. In a thin homogenous polymer layer where diffusion is Fickian, the oxygen concentration 1021 can be described by the diffusion equation in one-dimension.

  5. Stability and Stabilization of Two Time Scale Switched Systems in Discrete Time

    Microsoft Academic Search

    Ivan Malloci; Jamal Daafouz; Claude Iung

    2010-01-01

    In this technical note, stability and stabilization of two time scale switched linear systems in the singular perturbation form are addressed in discrete time. We show that, under an arbitrary switching rule, stability of the slow and fast switched subsystems is not sufficient to assess stability of the original two time scale switched system, even if the singular perturbation parameter

  6. Geometric structure of multiple time-scale nonlinear dynamical systems

    Microsoft Academic Search

    Sanjay Bharadwaj

    1999-01-01

    A new methodology to analyze time-scale structure of smooth finite-dimensional nonlinear dynamical systems is developed. This approach does not assume apriori knowledge of slow and fast variables for special coordinates that simplify the form of the nonlinear dynamics. Conventional approaches to analyze time-scale structure of nonlinear dynamics such as singular perturbation theory proceed from such specialized apriori knowledge which is

  7. Time Scales of Observation and Ontological Levels of Reality

    Microsoft Academic Search

    Alexey Alyushin

    2010-01-01

    My goal is to conceive how the reality would look like for hypothetical creatures that supposedly perceive on time scales\\u000a much faster or much slower than that of us humans. To attain the goal, I propose modelling in two steps. At step one, we have\\u000a to single out a unified parameter that sets time scale of perception. Changing substantially the

  8. Scaling approach for the time-dependent Kondo model

    E-print Network

    Tomaras, C

    2010-01-01

    We present a new nonperturbative method to deal with the time-dependent quantum many-body problem, which is an extension of Wegner's flow equations to time-dependent Hamiltonians. The formalism provides a scaling procedure for the set of time-dependent interaction constants. We apply these ideas to a Kondo model with a ferromagnetic exchange coupling switched on over a time scale $\\tau$. We show that the asymptotic expectation value of the impurity spin interpolates continuously between its quenched and adiabatic value.

  9. Scaling approach for the time-dependent Kondo model

    E-print Network

    C. Tomaras; S. Kehrein

    2010-11-04

    We present a new nonperturbative method to deal with the time-dependent quantum many-body problem, which is an extension of Wegner's flow equations to time-dependent Hamiltonians. The formalism provides a scaling procedure for the set of time-dependent interaction constants. We apply these ideas to a Kondo model with a ferromagnetic exchange coupling switched on over a time scale $\\tau$. We show that the asymptotic expectation value of the impurity spin interpolates continuously between its quenched and adiabatic value.

  10. Time and scale Hurst exponent analysis for financial markets

    NASA Astrophysics Data System (ADS)

    Matos, José A. O.; Gama, Sílvio M. A.; Ruskin, Heather J.; Sharkasi, Adel Al; Crane, Martin

    2008-06-01

    We use a new method of studying the Hurst exponent with time and scale dependency. This new approach allows us to recover the major events affecting worldwide markets (such as the September 11th terrorist attack) and analyze the way those effects propagate through the different scales. The time-scale dependence of the referred measures demonstrates the relevance of entropy measures in distinguishing the several characteristics of market indices: “effects” include early awareness, patterns of evolution as well as comparative behaviour distinctions in emergent/established markets.

  11. Multiresolution schemes for time-scaled propagation of wave packets

    NASA Astrophysics Data System (ADS)

    Frapiccini, Ana Laura; Hamido, Aliou; Mota-Furtado, Francisca; O'Mahony, Patrick F.; Piraux, Bernard

    2015-04-01

    We present a detailed analysis of the time-scaled coordinate approach and its implementation for solving the time-dependent Schrödinger equation describing the interaction of atoms or molecules with radiation pulses. We investigate and discuss the performance of multiresolution schemes for the treatment of the squeezing around the origin of the bound part of the scaled wave packet. When the wave packet is expressed in terms of B splines, we consider two different types of breakpoint sequences: an exponential sequence with a constant density and an initially uniform sequence with a density of points around the origin that increases with time. These two multiresolution schemes are tested in the case of a one-dimensional Gaussian potential and for atomic hydrogen. In the latter case, we also use Sturmian functions to describe the scaled wave packet and discuss a multiresolution scheme which consists of working in a Sturmian basis characterized by a set of nonlinear parameters. Regarding the continuum part of the scaled wave packet, we show explicitly that, for large times, the group velocity of each ionized wave packet goes to zero while its dispersion is suppressed, thereby explaining why, eventually, the scaled wave packet associated with the ejected electrons becomes stationary. Finally, we show that only the lowest scaled bound states can be removed from the total scaled wave packet once the interaction with the pulse has ceased.

  12. Resistivity scaling and electron relaxation times in metallic nanowires

    SciTech Connect

    Moors, Kristof, E-mail: kristof@itf.fys.kuleuven.be [Instituut voor Theoretische Fysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Imec, Kapeldreef 75, B-3001 Leuven (Belgium); Sorée, Bart; Magnus, Wim [Imec, Kapeldreef 75, B-3001 Leuven (Belgium); Physics Department, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); T?kei, Zsolt [Imec, Kapeldreef 75, B-3001 Leuven (Belgium)

    2014-08-14

    We study the resistivity scaling in nanometer-sized metallic wires due to surface roughness and grain-boundaries, currently the main cause of electron scattering in nanoscaled interconnects. The resistivity has been obtained with the Boltzmann transport equation, adopting the relaxation time approximation of the distribution function and the effective mass approximation for the conducting electrons. The relaxation times are calculated exactly, using Fermi's golden rule, resulting in a correct relaxation time for every sub-band state contributing to the transport. In general, the relaxation time strongly depends on the sub-band state, something that remained unclear with the methods of previous work. The resistivity scaling is obtained for different roughness and grain-boundary properties, showing large differences in scaling behavior and relaxation times. Our model clearly indicates that the resistivity is dominated by grain-boundary scattering, easily surpassing the surface roughness contribution by a factor of 10.

  13. Tethys- and Atlas-related deformations in the Triassic Basin, Algeria

    SciTech Connect

    Jackson, J.S.; Moore, S.R.; Quarles, A.I. [ARCO International Oil and Gas Company, Plano, TX (United States)

    1995-08-01

    Petroleum provinces of Algeria can be divided into Paleozoic and Mesozoic domains. Paleozoic basins are located on the Gondwanaland paleo-continent where the last significant tectonic episode is ascribed to the Late Paleozoic Hercynian Orogeny. Mesozoic basins are located on the south margin of the Neo-Tethyan seaway. These basins were subject to varying degrees of contractional deformation during the Cenozoic Atlas Orogeny. The Triassic Basin of Algeria is a Tethyan feature located above portions of the Paleozoic Oued M`ya and Ghadames Basins. Paleozoic strata are deeply truncated at the Hercynian Unconformity on a broad arch between the older basins. This is interpreted to reflect rift margin rebound during Carboniferous time. Continental Lower Triassic sediments were deposited in a series of northeast trending basins which opened as the Neo-Tethys basin propagated from east to west between Africa and Europe. Middle Triassic marine transgression from the east resulted in evaporate deposition persisting through the Early Jurassic. Passive margin subsidence associated with carbonate marine deposition continued through the Early Cretaceous. Several zones of coeval wrench deformation cross the Atlas and adjoining regions. In the Triassic Basin, inversion occurred before the end of the Early Cretaceous. This episode created discrete uplifts, where major hydrocarbon accumulations have been discovered, along northeast trending lineaments. During the Eocene, the main phase of the Atlas Orogeny produced low amplitude folding of Jurassic and Cretaceous sediments. The folds detach within the Triassic-Jurassic evaporate interval. Many of these folds have been tested without success, as the deeper reservoirs do not show structural closure.

  14. Photic Zone Euxinia During the Permian-Triassic Superanoxic Event

    Microsoft Academic Search

    Kliti Grice; Changqun Cao; Gordon D. Love; Michael E. Böttcher; Richard J. Twitchett; Emmanuelle Grosjean; Roger E. Summons; Steven C. Turgeon; William Dunning; Yugan Jin

    2005-01-01

    Carbon and sulfur isotopic data, together with biomarker and iron speciation analyses of the Hovea-3 core that was drilled in the Perth Basin, Western Australia, indicate that euxinic conditions prevailed in the paleowater column during the Permian-Triassic superanoxic event. Biomarkers diagnostic for anoxygenic photosynthesis by Chlorobiaceae are particularly abundant at the boundary and into the Early Triassic. Similar conditions prevailed

  15. ORIGINAL ARTICLE Marine flooding event in continental Triassic facies identified

    E-print Network

    Benton, Michael

    ORIGINAL ARTICLE Marine flooding event in continental Triassic facies identified by a nothosaur is characterized by continental Triassic redbed facies com- posed of sandstones and siltstones, with gypsum Western expressions of the suc- cession. The continental facies (redbeds) occur along the southeastern

  16. Multiple-time scales analysis of physiological time series under neural control

    NASA Technical Reports Server (NTRS)

    Peng, C. K.; Hausdorff, J. M.; Havlin, S.; Mietus, J. E.; Stanley, H. E.; Goldberger, A. L.

    1998-01-01

    We discuss multiple-time scale properties of neurophysiological control mechanisms, using heart rate and gait regulation as model systems. We find that scaling exponents can be used as prognostic indicators. Furthermore, detection of more subtle degradation of scaling properties may provide a novel early warning system in subjects with a variety of pathologies including those at high risk of sudden death.

  17. Hierarchical structure and multi time-scale in large scale dynamical systems

    Microsoft Academic Search

    Koichi Tojo; Koji Tsumura

    2008-01-01

    In this paper, we deal with approximation methods of large-scale systems which describe the macroscopic behavior of the whole system and simultaneously the partially microscopic one of the objective subsystems. We propose a hierarchical representation of such large-scale systems by employing the connection graph structure of the elements and multiple time-scale dynamics. The approximation accuracy is rigorously induced and numerical

  18. The time-scale associated with flux expulsion

    NASA Astrophysics Data System (ADS)

    Moffatt, H. K.; Kamkar, H.

    A simple model problem is solved in order to show that the time-scale associated with the process of flux expulsion is tfe = Rm1/3t0 where t0 is a time-scale characterising the flow (for example, the eddy turnover time, or inverse shear rate) and Rm is the magnetic Reynolds number. By decomposing the vector potential into a product of a rapidly varying part (in space) and a slowly varying part, it is shown how numerical work can be extended to much higher values of Rm than has been achieved hitherto.

  19. Investigating the Geologic Time Scale: Creating posters to Display Trends in Geologic Time

    NSDL National Science Digital Library

    kim Atkins

    This observational inquiry activity involving careful descriptions of rocks and fossil including age will be used to create a scalar accurate geologic time scale. Students will observe and learn that the geologic time scale was created based on changes in fossil, rock, and atmospheric changes.

  20. Common scaling patterns in intertrade times of U. S. stocks.

    PubMed

    Ivanov, Plamen Ch; Yuen, Ainslie; Podobnik, Boris; Lee, Youngki

    2004-05-01

    We analyze the sequence of time intervals between consecutive stock trades of thirty companies representing eight sectors of the U.S. economy over a period of 4 yrs. For all companies we find that: (i) the probability density function of intertrade times may be fit by a Weibull distribution, (ii) when appropriately rescaled the probability densities of all companies collapse onto a single curve implying a universal functional form, (iii) the intertrade times exhibit power-law correlated behavior within a trading day and a consistently greater degree of correlation over larger time scales, in agreement with the correlation behavior of the absolute price returns for the corresponding company, and (iv) the magnitude series of intertrade time increments is characterized by long-range power-law correlations suggesting the presence of nonlinear features in the trading dynamics, while the sign series is anticorrelated at small scales. Our results suggest that independent of industry sector, market capitalization and average level of trading activity, the series of intertrade times exhibit possibly universal scaling patterns, which may relate to a common mechanism underlying the trading dynamics of diverse companies. Further, our observation of long-range power-law correlations and a parallel with the crossover in the scaling of absolute price returns for each individual stock, support the hypothesis that the dynamics of transaction times may play a role in the process of price formation. PMID:15244883

  1. Tectonic setting of the Late Triassic volcaniclastic series of the Luang Prabang Basin, Laos, and geodynamic implications from the Triassic to Jurassic in SE Asia

    NASA Astrophysics Data System (ADS)

    Rossignol, Camille; Bourquin, Sylvie; Dabard, Marie-Pierre; Hallot, Erwan; Poujol, Marc; Nalpas, Thierry

    2014-05-01

    The Luang Prabang Basin, located on the eastern margin of the Indochina block, is mainly composed of volcaniclastic continental deposits. The interpretation of U-Pb zircon geochronological dates shows that volcanism is contemporaneous with the sedimentation during the Late Triassic (c.a. 225 to 215 Ma; Blanchard et al., 2013, J. Asian Earth Sci., 70-71; 8-26). At the same time, volcanism is also known along the Eastern margin of the Indochina block (present day Thailand). There are currently two main contrasting interpretations concerning the tectonic setting related to these volcanic events: are they arc-related (e.g. Barr et al., 2006, J. Geol. Soc. London, 163; 1037-1046) or post collisional (e.g. Srichan et al., 2009, Island Arc, 18; 32-51)? We have performed geochemical analysis on both sedimentary and volcanic rocks of the Luang Prabang Basin in order to evaluate the relationships between the volcanic events and to propose a geodynamic interpretation. The geochemical characteristics of the Luang Prabang Late Triassic volcaniclastic and volcanic rocks are compatible with a volcanic arc setting. The confrontation of these results with the stratigraphic evolution of the eastern margin of the Indochina block leads to reconsider the Late Triassic to Jurassic geodynamic evolution of this area. Arc-related volcanism seems to occur during nearly the whole Triassic, implying a subduction of the Paleotethys beneath the Indochina block. As the stratigraphic record of north-eastern Thailand and western Myanmar shows an important stratigraphic gap spanning from the Early to the Middle Jurassic, the collision between the Indochina and the Sibumasu blocks likely occurred at that period.

  2. Stability of nonlinear systems with three time scales

    Microsoft Academic Search

    C. A. Desoer; S. M. Shahruz

    1986-01-01

    We study the asymptotic stability of a singularly perturbed nonlinear time-invariant systemS?v, which has three vastly different time scales. The systemS?v is approximated by three simpler systems over different time intervals. We give a straightforward proof of the fact that the asymptotic stability ofS?v is guaranteed when the equilibrium points of the three simpler systems are exponentially stable and when

  3. On Nonlinear Control Systems with Multiple Time Scales

    Microsoft Academic Search

    G. Grammel

    2004-01-01

    An order reduction procedure for nonlinear control systems with multiple time scales is introduced. A limit system for the slowest motion describing the situation that all singular perturbation parameters vanish is constructed. For this purpose a refined two-scale averaging method is used in a way that allows a re-iteration. For vanishing control range the results reduce to the well-known Tychonoff

  4. Dinosaurs in the Early and Mid Triassic?—The footprint evidence from Britain

    Microsoft Academic Search

    Michael J. King; Michael J. Benton

    1996-01-01

    The oldest skeletons of dinosaurs date from the Late Triassic (Carnian), but supposed dinosaur footprints have been reported from Lower and Mid Triassic rocks, dated up to 20 m.y. earlier. Supposed Lower Triassic dinosaur footprints from Britain are reinterpreted as ripple marks, mud rip-up clasts, and possible limulid prints. The Middle Triassic material is reinterpreted as partial specimens of Chirotherium,

  5. The Colorado Plateau Coring Project (CPCP): A Continuous Cored Record of Triassic Continental Environmental Change in Western North America

    NASA Astrophysics Data System (ADS)

    Olsen, P. E.; Geissman, J. W.; Gehrels, G. E.; Irmis, R. B.; Kent, D. V.; Mundil, R.; Parker, W.; Sha, J.; Molina-Garza, R. S.; Kuerschner, W.; Bachmann, G. H.; Schaller, M. F.; Zakharova, N. V.; Colbert, M.

    2014-12-01

    The Triassic Period (251.9-201.3 Ma) is bound by two of the Earth's largest mass extinctions, suffered several giant bolide impacts and eruption of 3 large igneous provinces, and witnessed evolution of the main components of modern tetrapod communities, and yet has sparse geochronological calibration. To bridge this gap, NSF- and ICDP-funded coring of Phase 1 of the CPCP finished in 12/2013 with the recovery of two major cores (1A, 518m and 2B, 253m; 31km apart) from opposites sides of Petrified Forest National Park spanning nearly the entire Triassic sequence (Chinle & Moenkopi fms) with many U-Pb datable levels (1,2,3) and a recoverable paleomagnetic polarity record (4). The cores will provide a U-Pb and paleomagnetic exportable time scale and sedimentary and geochemical proxies with undoubted superposition testing the motivating hypotheses of: 1) the accuracy of orbitally-paced cyclicity of the Newark APTS (5); 2) apparent climate trends as a function of drift through climate belts (6) and atmospheric CO2 (7); 3) the temporal link between the mid-Late Triassic biotic turnover and the ~100 km Manicouagan impact (1); and 4) the delayed ecological dominance of dinosaurs coupled to climate-driven provinciality (1,8). For orientation, the cores were drilled using a azimuth-tracking device, deviated 30° and 15° from vertical to the SE and S, and CT-scanned. The unprecedented sedimentological and stratigraphic detail visible in the CT-scans, and geophysical logs, plus the ~100% recovery promises successful tests of the motivating hypotheses and provide a superbly detailed reference section for this key episode in Earth system history. 1, Irmis+,2011, EPSL 309:258; 2, Ramazani+, 2011, GSA Bull. 123:2142; 3, Ramazani+, 2014, AJS 314:981; 4, Steiner & Lucas, 2000, JGR B 105:25791; 5, Kent & Olsen, 1999, JGR 104(B6):12831-12841; 6, Kent and Tauxe, 2005, Science 307:240-244; 7, Schaller+, 2012, EPSL 323-324:27-39; 8, Kent +, 2014, PNAS 111:7958-7963.

  6. An algorithm for the Italian atomic time scale

    NASA Technical Reports Server (NTRS)

    Cordara, F.; Vizio, G.; Tavella, P.; Pettiti, V.

    1994-01-01

    During the past twenty years, the time scale at the IEN has been realized by a commercial cesium clock, selected from an ensemble of five, whose rate has been continuously steered towards UTC to maintain a long term agreement within 3 x 10(exp -13). A time scale algorithm, suitable for a small clock ensemble and capable of improving the medium and long term stability of the IEN time scale, has been recently designed taking care of reducing the effects of the seasonal variations and the sudden frequency anomalies of the single cesium clocks. The new time scale, TA(IEN), is obtained as a weighted average of the clock ensemble computed once a day from the time comparisons between the local reference UTC(IEN) and the single clocks. It is foreseen to include in the computation also ten cesium clocks maintained in other Italian laboratories to further improve its reliability and its long term stability. To implement this algorithm, a personal computer program in Quick Basic has been prepared and it has been tested at the IEN time and frequency laboratory. Results obtained using this algorithm on the real clocks data relative to a period of about two years are presented.

  7. Trends in Surface Radiation Budgets at Climatic Time Scales

    NASA Astrophysics Data System (ADS)

    Pinker, Rachel T.; Zhang, Banglin; Ma, Yingtao

    2015-04-01

    For assessment of variability and trends in the Earth Radiation Balance, information is needed at climatic time scales. Satellite observations have been instrumental for advancing the understanding of the radiative balance at global scale, however, due to the frequent changes in the observing systems, the length of available satellite records is limited. In this paper we report on an effort to synthesize satellite observations from independent sources to estimates shortwave, longwave and spectral surface radiative fluxes at climatic time scales and use them to learn about their variability and trends. The radiative fluxes were derived in the framework of the MEaSURES and NEWS programs; they are evaluated against ground observations and compared to independent satellite and model estimates. Attention is given to updates on the radiative balance as compared to what is known from shorter time records and from models.

  8. Mixing Time Scales in a Supernova-Driven Interstellar Medium

    E-print Network

    Miguel A. de Avillez; Mordecai-Mark Mac Low

    2002-08-23

    We study the mixing of chemical species in the interstellar medium (ISM). Recent observations suggest that the distribution of species such as deuterium in the ISM may be far from homogeneous. This raises the question of how long it takes for inhomogeneities to be erased in the ISM, and how this depends on the length scale of the inhomogeneities. We added a tracer field to the three-dimensional, supernova-driven ISM model of Avillez (2000) to study mixing and dispersal in kiloparsec-scale simulations of the ISM with different supernova (SN) rates and different inhomogeneity length scales. We find several surprising results. Classical mixing length theory fails to predict the very weak dependence of mixing time on length scale that we find on scales of 25--500 pc. Derived diffusion coefficients increase exponentially with time, rather than remaining constant. The variance of composition declines exponentially, with a time constant of tens of Myr, so that large differences fade faster than small ones. The time constant depends on the inverse square root of the supernova rate. One major reason for these results is that even with numerical diffusion exceeding physical values, gas does not mix quickly between hot and cold regions.

  9. Memory on multiple time-scales in an Abelian sandpile

    NASA Astrophysics Data System (ADS)

    Sokolov, Andrey; Melatos, Andrew; Kieu, Tien; Webster, Rachel

    2015-06-01

    We report results of a numerical analysis of the memory effects in two-dimensional Abelian sandpiles. It is found that a sandpile forgets its instantaneous configuration in two distinct stages: a fast stage and a slow stage, whose durations roughly scale as N and N2 respectively, where N is the linear size of the sandpile. We confirm the presence of the longer time-scale by an independent diagnostic based on analysing emission probabilities of a hidden Markov model applied to a time-averaged sequence of avalanche sizes. The application of hidden Markov modelling to the output of sandpiles is novel. It discriminates effectively between a sandpile time series and a shuffled control time series with the same time-averaged event statistics and hence deserves further development as a pattern-recognition tool for Abelian sandpiles.

  10. The evidence for ocean acidification across the Triassic-Jurassic boundary

    NASA Astrophysics Data System (ADS)

    Martindale, R. C.; Greene, S. E.; Ritterbush, K. A.; Bottjer, D. J.; Corsetti, F. A.; Berelson, W.

    2012-12-01

    The end-Triassic extinction is one of the "Big Five" mass extinctions of the Phanerozoic and until recently no consensus regarding the cause of this extinction has been established. Over the last decade, a robust temporal correlation between the eruption of the Central Atlantic Magmatic Province (CAMP) and the end-Triassic extinction has been established. This correlation has led to the speculation that the release of CO2 and volatiles from the CAMP flood basalts induced a carbon cycle perturbation that acidified the Triassic oceans. It has also been suggested that an acidification event could have been the key mechanism that caused the end-Triassic marine ecosystem collapse. By combining observations and data from multiple fields such as volcanology, paleoceanography, chemostratigraphy, paleontology, and sedimentology, one can assess whether or not there was an ocean acidification event and to what degree it contributed to the extinction. The eruption of the CAMP flood basalts began at the very end of the Triassic period, albeit before the official Triassic-Jurassic (T-J) boundary, (defined as the first Jurassic ammonite). CAMP is one of the largest continental flood basalts of the Phanerozoic (2-4 million cubic km) and was emplaced extremely rapidly (<1.6-2 Myr) in three to five pulses (possibly hundreds to tens of thousands of years). The massive injection of CAMP CO2 and other volcanic volatiles over such a short period of time would have caused a major change in ocean carbonate chemistry and, if short enough in duration, could have caused significant declines in oceanic carbonate saturation state (an ocean acidification event), possibly even undersaturating parts of the surface ocean with respect to aragonite and calcite. Although the change in saturation state of the ocean is extremely difficult to detect or quantify in the rock record, there is a distinct paucity of primary carbonate sediments in the T-J boundary interval, consistent with an ocean acidification event. Of the seventeen T-J boundary sections only three or four record potentially continuous carbonate deposition across the extinction interval, even so these carbonates are often marls and so may not be truly continuous. Finally, the end-Triassic extinction was particularly selective against pH-sensitive organisms (more so than perhaps any other extinction event). Not only was this extinction event one of the most severe extinctions of the 'Modern Fauna' in the geologic record, it also decimated reef ecosystems built by corals and hypercalcified sponges. End-Triassic extinction rates amongst acid-intolerant organisms and ecosystems are elevated and differ significantly from background extinction so that ocean acidification is a reasonable explanation for the interpreted extinction selectivity during this time interval. Given the volcanic, geochemical, sedimentological, and paleontological changes or events across the T-J interval it is likely that the end-Triassic extinction was heavily influenced by a CAMP-induced ocean acidification event. The dramatic taxonomic and ecosystem turnover at the T-J event implies that short-term acidification events may have long-term effects on ecosystems, a repercussion that has not previously been correlated with acidification events and has implications for future changes in ocean chemistry.

  11. The interpretation of cyclic successions of the Middle and Upper Triassic of the Northern and Southern Alps

    NASA Astrophysics Data System (ADS)

    Satterley, A. K.

    1996-06-01

    Theories regarding the formation of sedimentary cycles in the 3rd, 4th and 5th order bands are reviewed with reference to the Middle and Upper Triassic of the Northern Calcareous Alps (NCA) and Southern Alps. Milankovitch, autocyclic and tectonic theories are discussed, together with an evaluation of concepts of chaotic sedimentation and a case example from the NCA. Concerning eustasy, 3rd, 4th and 5th order sea-level fluctuations were probably a low-amplitude, low-rate phenomenon caused by fluctuations in the volume of mountain glaciers and ocean water during the Triassic. The Mid and Late Triassic was a non-glacial interval in which polar regions may have been ice-free, so glacio-eustasy can not be expected. Eustatic sea-level variations in the 3rd, 4th and 5th order bands seem to have left no useful imprint on cyclic successions in the region; whatever record there may be is inextricably mixed with two other signals (tectonic activity and autocycles). The review shows how sedimentation in the Triassic of the area was strongly influenced by tectonic activity. This is as true for the Middle and Late Triassic of the NCA as it is for the Southern Alps. Tectonic activity may be responsible for large-scale cyclicity (4th to 3rd order scale). Although seismogenic structures have yet to be identified and described in carbonate successions of the Alps, candidates do exist. Slumped and microfaulted layers in laminated sediments of the Seefeld Basin (Upper Triassic, NCA) have been described as the products of fault movements. The sedimentary record from the NCA and Southern Alps also leaves little doubt that autocyclic processes were important in all environments except perhaps the deep, sediment-starved basins. Most small-scale platform cycles (5th order scale) in the region can be related to autocyclic processes and, in shallow basinal successions, to events such as storms. Previous workers have not been consistent in their interpretation of cyclic successions in the area, applying diverse theories to similar successions. So far, the Steinplatte-Hochkönig platform, with attached Kössen Basin, is the only example interpreted with reference to tectonics and autocyclicity; eustasy was probably not the most important factor in cycle generation in the Triassic of the NCA and Southern Alps. Such an approach could prove useful in future studies.

  12. Relativistic fireballs - Energy conversion and time-scales

    NASA Technical Reports Server (NTRS)

    Rees, M. J.; Meszaros, P.

    1992-01-01

    The expansion energy of a relativistic fireball can be reconverted into radiation when it interacts with an external medium. For expansion with Lorentz factors greater than or approximately equal to 1000 into a typical galactic environment, the corresponding time-scale in the frame of the observer is of the order of seconds. This mechanism would operate in any cosmological scenario of gamma-ray bursts involving initial energies of order a percent of a stellar rest mass, and implies photon energies and time-scales compatible with those observed in gamma-ray bursts.

  13. Dynamics symmetries of Hamiltonian system on time scales

    SciTech Connect

    Peng, Keke, E-mail: pengkeke88@126.com; Luo, Yiping, E-mail: zjstulyp@126.com [Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018 (China)] [Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2014-04-15

    In this paper, the dynamics symmetries of Hamiltonian system on time scales are studied. We study the symmetries and quantities based on the calculation of variation and Lie transformation group. Particular focus lies in: the Noether symmetry leads to the Noether conserved quantity and the Lie symmetry leads to the Noether conserved quantity if the infinitesimal transformations satisfy the structure equation. As the new application of result, at end of the article, we give a simple example of Noether symmetry and Lie symmetry on time scales.

  14. TIME DELAY AND MOTION ESTIMATORS BASED ON DIGITAL FAST TIME-SCALING OF RANDOM SIGNALS

    Microsoft Academic Search

    Gaetano Giunta

    The estimation of time-delay and time-scaling is required in many signal processing applications. A parabolic approximation was recently suggested for fine estimation of time delay from sampled signals. The method directly extends to scaling estimation by a parallel multi-rate sampling of the analog received signal. Such rescaling can be implemented by digital techniques and two efficient algorithms are here devised

  15. Fault rock texture and porosity type in Triassic dolostones

    NASA Astrophysics Data System (ADS)

    Agosta, Fabrizio; Grieco, Donato; Bardi, Alessandro; Prosser, Giacomo

    2015-04-01

    Preliminary results of an ongoing project aimed at deciphering the micromechanics and porosity evolution associated to brittle deformation of Triassic dolostones are presented. Samples collected from high-angle, oblique-slip, 10's to 100's m-throw normal faults crosscutting Mesozoic carbonates of the Neo Tethys (Campanian-Lucanian Platform) are investigated by mean of field geological mapping, optical microscopy, SEM and image analyses. The goal is to characterize in detail composition, texture and porosity of cataclastic rocks in order to assess the structural architecture of dolomitic fault cores. Moreover, the present study addresses the time-space control exerted by several micro-mechanisms such as intragranular extensional fracturing, chipping and shear fracturing, which took place during grain rolling and crushing within the evolving faults, on type, amount, dimensions and distribution of micropores present within the cataclastic fault cores. Study samples are representative of well-exposed dolomitic fault cores of oblique-slip normal faults trending either NW-SE or NE-SW. The high-angle normal faults crosscut the Mesozoic carbonates of the Campanian-Lucanian Platform, which overrode the Lagonegro succession by mean of low-angle thrust faults. Fault throws are measured by considering the displaced thrust faults as key markers after large scale field mapping (1:10,000 scale) of the study areas. In the field, hand samples were selected according to their distance from main slip surfaces and, in some case, along secondary slip surfaces. Microscopy analysis of about 100 oriented fault rock samples shows that, mostly, the study cataclastic rocks are made up of dolomite and sparse, minute survivor silicate grains deriving from the Lagonegro succession. In order to quantitatively assess the main textural classes, a great attention is paid to the grain-matrix ratio, grain sphericity, grain roundness, and grain sorting. By employing an automatic box-counting technique, the fractal dimension of representative samples is also computed. Results of such a work shows that five main textural types are present: 1) fractured and fragmented dolomites; 2) protocataclasites characterized by intense intragranular extensional fracturing; 3) cataclasites due to a chipping-dominated mechanism; 4) cataclasites and ultracataclasites with pronounced shear fracturing; 5) cemented fault rocks, which localize along the main slip surfaces. The first four textural types are therefore indicative to the fault rock maturity within individual cataclastic fault cores. A negative correlation among grain-matrix ratio and grain sphericity, roundness and sorting is computed, which implies that ultracataclasites are made up of more spherical and rounded smaller grains relative to cataclasites and protocataclasites. Each textural type shows distinct D0-values (box-counting dimension). As expected, a good correlation between the D0-value and fault rock maturity is computed. Ongoing analysis of selected images obtained from representative samples of the five textural classes will shed lights on the relative role played by the aforementioned micro-mechanisms on the porosity evolution within the cataclastic fault cores.

  16. Time Scale Calculus - a new perspectives for synthetic seismogram calculations

    NASA Astrophysics Data System (ADS)

    Waskiewicz, Kamil; Debski, Wojciech

    2013-04-01

    Synthetic, numerically generated seismograms are one of the key factors of any interpretation of recorded seismic data. At the early stage of development, calculation of full seismic waveforms was impossible due to a limited computational resource so we were forced to used only some selected characteristics of seismic waves relatively easy for numerical calculations like first arrival times, maximum amplitude, approximate source spectra, to name a few. Continues development of computational resources as well as progress in numerical techniques has opened possibilities of generation the full, 3-component seismograms incorporating many physically important elements like wave attenuation, anisotropy or randomness of the media. Although achieved results are impressive we still need new numerical methods to tackle existing problems with the synthetic seismogram generation. In this contribution we present a novel approach to discretization of the wave equation which brings together continues and discrete numerical analysis of the seismic waves. The foundations of this new technique, called Time Scale Calculus, have been formulated by Hilger in late eighties and is very dynamically developing. The Time scale calculus, due to its universality seems to have a great potential when practical applications are considered. Thus we have decided to bring the Time Scale calculus concept closer to geophysical, or more precisely to seismological applications. This presentation is intend as a basic introduction to the time scales calculus considered from seismological point of view. We shortly present and discuss the possibility of using the Time Scales (TS) technique for solving the simplest acoustic 2D wave equation keeping in mind its particular applications for mining induced seismicity.

  17. Satellite attitude prediction by multiple time scales method

    NASA Technical Reports Server (NTRS)

    Tao, Y. C.; Ramnath, R.

    1975-01-01

    An investigation is made of the problem of predicting the attitude of satellites under the influence of external disturbing torques. The attitude dynamics are first expressed in a perturbation formulation which is then solved by the multiple scales approach. The independent variable, time, is extended into new scales, fast, slow, etc., and the integration is carried out separately in the new variables. The theory is applied to two different satellite configurations, rigid body and dual spin, each of which may have an asymmetric mass distribution. The disturbing torques considered are gravity gradient and geomagnetic. Finally, as multiple time scales approach separates slow and fast behaviors of satellite attitude motion, this property is used for the design of an attitude control device. A nutation damping control loop, using the geomagnetic torque for an earth pointing dual spin satellite, is designed in terms of the slow equation.

  18. Robust control of multivariable two-time-scale nonlinear systems

    Microsoft Academic Search

    Panagiotis D. Christofides; Prodromos Daoutidis

    1997-01-01

    This paper focuses on the synthesis of well-conditioned multivariable robust controllers for a broad class of multi-input multi-output two-time-scale nonlinear systems with time-varying uncertain variables, modeled within the framework of singular perturbations. The proposed controller stabilizes the fast dynamics, guarantees boundedness of trajectories, and ensures that the ultimate discrepancy between the outputs and the external reference inputs in the closed-loop

  19. Time and frequency scale modification of speech signals

    Microsoft Academic Search

    Brett Ninness; Soren John Henriksen

    2000-01-01

    This paper presents new and improved methods for independently modifying the time and pitch scale of acoustic signals, with an emphasis on speech signals. The algorithms developed here use parametric (sinusoidal) modelling techniques introduced by other authors, but new ideas are presented here that achieve improved output quality with decreased computational load. In particular, speech quality is improved by using

  20. Speech Compensation for Time-Scale-Modified Auditory Feedback

    ERIC Educational Resources Information Center

    Ogane, Rintaro; Honda, Masaaki

    2014-01-01

    Purpose: The purpose of this study was to examine speech compensation in response to time-scale-modified auditory feedback during the transition of the semivowel for a target utterance of /ija/. Method: Each utterance session consisted of 10 control trials in the normal feedback condition followed by 20 perturbed trials in the modified auditory…

  1. Gott Time Machines, BTZ Black Hole Formation, and Choptuik Scaling

    NASA Astrophysics Data System (ADS)

    Birmingham, Danny; Sen, Siddhartha

    2000-02-01

    We study the formation of Bañados-Teitelboim-Zanelli black holes by the collision of point particles. It is shown that the Gott time machine, originally constructed for the case of vanishing cosmological constant, provides a precise mechanism for black hole formation. As a result, one obtains an exact analytic understanding of the Choptuik scaling.

  2. Improvement of Rate Shift in Average Atomic Time Scale Algorithm

    Microsoft Academic Search

    Yuko Hanado; Mizuhiko Hosokawa

    2008-01-01

    In an average atomic time scale algorithm, we developed a new method of suppressing the influence of a large sudden rate shift in some clocks. The method entails two points. One is to add a clock rate check process. The weight of a bad clock is forced to be zero if its latest rate largely changes from the past rate.

  3. Nonlinear Dynamics in Psychophysiology - Importance of Time Scales

    E-print Network

    W. Klonowski

    2004-08-17

    Presented theory of feelings and emotions is based on Nonlinear Dynamics and Theory of Complex Systems. The most important assumption is that the brain may be considered to be composed of subsystems characterized by different characteristic time scales. The theory explains a possible role of feelings and emotions in cognition. We propose to call presented theory Chaosensology.

  4. AGN variability time scales and the discrete-event model

    E-print Network

    P. Favre; T. J. -L. Courvoisier; S. Paltani

    2005-08-29

    We analyse the ultraviolet variability time scales in a sample of 15 Type 1 Active Galactic Nuclei (AGN) observed by IUE. Using a structure function analysis, we demonstrate the existence in most objects of a maximum variability time scale of the order of 0.02-1.00 year. We do not find any significant dependence of these maximum variability time scales on the wavelength, but we observe a weak correlation with the average luminosity of the objects. We also observe in several objects the existence of long-term variability, which seems decoupled from the short-term one. We interpret the existence of a maximum variability time scale as a possible evidence that the light curves of Type 1 AGN are the result of the superimposition of independent events. In the framework of the so-called discrete-event model, we study the event energy and event rate as a function of the object properties. We confront our results to predictions from existing models based on discrete events. We show that models based on a fixed event energy, like supernova explosions, can be ruled out. In their present form, models based on magnetic blobs are also unable to account for the observed relations. Stellar collision models, while not completely satisfactory, cannot be excluded.

  5. Multiple-time-scales in singularly perturbed systems

    Microsoft Academic Search

    David H. Owens

    1985-01-01

    Conditions for the existence of well-defined time-scales of a general, autonomous singularly perturbed linear system in Rn are described in terms of asymptotic eigenstructure of the inverse system matrix and related to Wonham's {A,B} - invariant subspace algorithm. One consequence of the results is a strong geometric link between singular perturbation and root-locus theory.

  6. Short Time-Scale Emission Line Variations in Mira B

    NASA Astrophysics Data System (ADS)

    Chamber, H. L., II; Moffett, T. J.; Barnes, T. G., III

    1997-05-01

    Spectra of Mira were taken at McDonald Observatory near Mira A minimum in December 1975 using an image tube spectrograph. Series of spectra on a two to three minute time-scale show significant line strength variations in the emission lines associated with Mira B.

  7. Impulsive nonlocal differential equations through differential equations on time scales

    Microsoft Academic Search

    Mieczys?aw Cicho?; Bianca Satco; Aneta Sikorska-Nowak

    2011-01-01

    We propose a non-standard approach to impulsive differential equations in Banach spaces by embedding this type of problems into differential (dynamic) problems on time scales. We give an existence result for dynamic equations and, as a consequence, we obtain an existence result for impulsive differential equations.

  8. Multiple time scale numerical methods for the inverted pendulum problem

    E-print Network

    Tsai, Yen-Hsi Richard

    Multiple time scale numerical methods for the inverted pendulum problem Richard Sharp1, Yen (HMM) [1]. We apply the methods to compute the averaged path of the inverted pendulum under a highly and thus compute the average path of the inverted pendulum. 1 Introduction The focus of this paper

  9. MULTIPLE TIME SCALE NUMERICAL METHODS FOR THE INVERTED PENDULUM PROBLEM

    E-print Network

    Soatto, Stefano

    MULTIPLE TIME SCALE NUMERICAL METHODS FOR THE INVERTED PENDULUM PROBLEM RICHARD SHARP, YEN-HSI TSAI multiscale methods (HMM) [1]. We apply the methods to compute the averaged path of the inverted pendulum approximate the averaged equation and thus compute the average path of the inverted pendulum. 1. INTRODUCTION

  10. 1. Forces and thermostats 1 Irreversibility time scale

    E-print Network

    a system is modeled as an aggregate of molecules interacting via conservative forces. A corresponding1. Forces and thermostats 1 Irreversibility time scale G.Gallavotti I.N.F.N. Roma 1, Fisica Roma1 language, for a system subject to internal conservative forces in­ teracting with ``external'' thermostats

  11. Gott Time Machines, BTZ Black Hole Formation, and Choptuik Scaling

    E-print Network

    Danny Birmingham; Siddhartha Sen

    1999-08-23

    We study the formation of BTZ black holes by the collision of point particles. It is shown that the Gott time machine, originally constructed for the case of vanishing cosmological constant, provides a precise mechanism for black hole formation. As a result, one obtains an exact analytic understanding of the Choptuik scaling.

  12. Causality across rainfall time scales revealed by continuous wavelet transforms

    E-print Network

    Katul, Gabriel

    Click Here for Full Article Causality across rainfall time scales revealed by continuous wavelet; revised 3 December 2009; accepted 27 January 2010; published 31 July 2010. [1] Rainfall variability occurs by atmospheric circulation. A central topic in rainfall research is to determine whether rainfall variability

  13. Anoxia Precedes the end-Triassic Mass Extinction: Evidence from the Kennecott Point Formation, British Columbia

    NASA Astrophysics Data System (ADS)

    Kasprak, A. H.; Sepúlveda, J.; Price-Waldman, R.; Williford, K. H.; Whiteside, J. H.; Summons, R. E.

    2011-12-01

    The end-Triassic mass extinction (ETE), at 201.4 million years ago, is one of the five largest ecologic disasters of the Phanerozoic eon. Few geologic sections offer the potential to reconstruct environmental and ecological changes at this time in the marine realm with global significance. The Kennecott Point Formation in Haida Gwaii (formerly the Queen Charlotte Islands), British Columbia, preserves a thick sequence of calcareous shales and siltstones deposited on late Triassic basaltic rocks interpreted to be an oceanic plateau resting within the Panthalassic basin, the largest ocean basin at the time of the Triassic-Jurassic transition. This section, which spans the late Norian to the mid-Hettangian, is plausibly the most representative of the global ocean system at this time; however, environmental reconstructions have been mostly based on bulk carbon and sulfur isotope records. Here, we present a record of molecular fossils (biomarkers) and indices indicative of ecological and redox changes (i.e., algal steranes and bacterial hopanes, gammacerane index, homohopane index, 2- and 3- methyl hopane indices) from the Kennecott Point Formation to argue for a period of low oxygen conditions associated with increased stratification, ecological changes, and disrupted nutrient cycling directly preceding the end-Triassic mass extinction. We couple these results with biomarkers indicative of terrestrial input and vegetation disturbance (tricyclic diterpanes and polycyclic aromatic hydrocarbons) to clarify the relationship between ocean biogeochemistry and environmental changes in the terrestrial realm. This record provides new evidence for changing marine conditions preceding and associated with the ETE and allows for a more rigorous investigation into the chronology of events hypothesized to be mechanistically linked to this mass extinction, including abrupt global warming, major alterations to marine primary productivity, and terrestrial vegetation die-off.

  14. Early Triassic conodonts of Jiarong, Nanpanjiang Basin, southern Guizhou Province, South China

    NASA Astrophysics Data System (ADS)

    Chen, Yanlong; Jiang, Haishui; Lai, Xulong; Yan, Chunbo; Richoz, Sylvain; Liu, Xiaodan; Wang, Lina

    2015-06-01

    Jiarong (Huishui County, Guizhou Province, South China) is a key locality for the study of the Early Triassic recovery after the end-Permian mass extinction. The size reduction of conodonts at the Smithian/Spathian transition was first documented in Jiarong, and it is also a locality that contributes to the documentation of the Early Triassic paleo-seawater temperatures. In the Jiarong sections, thirteen conodont zones were identified for the Early Triassic; in ascending order, they are Hindeodus parvus Zone, Hindeodus sosioensis Zone, Clarkina krystyni Zone, Neoclarkina discreta Zone, Neospathodus cristagalli-Eurygnathodus costatus assemblage zone, Novispathodus waageni eowaageni Zone, Novispathodus waageni waageni Zone, Discretella discreta Zone, Pachycladina-Parachirognathus assemblage zone, Novispathodus pingdingshanensis Zone, Icriospathodus collinsoni Zone, Triassospathodus homeri Zone, Triassospathodus triangularis Zone. These conodont zones in the Jiarong sections improve the global correlation of Early Triassic sections and also provide better regional age constraints in an area that is important for studies of recovery from the extinction. Based on the first appearance of Nv. waageni eowaageni, the Induan/Olenekian boundary is recognized at 3.6 m above the base of the Jiarong III Section. The dominance of blade-shaped (segminate) conodonts was replaced by gondola-shaped (segminiplanate) conodonts twice; the first time was in the late Griesbachian, and the second time was in the early Spathian. The dominance of segminiplanate conodonts probably indicates that the deeper seawater environment became more oxygenated during the late Griesbachian and early Spathian for short time intervals, as it is believed that the Griesbachian segminiplanate conodonts favored deeper oxygenated water habitats. A new genus, Spathogondolella gen. nov., and a new species, Spathogondolella jiarongensis sp. nov., have been recognized.

  15. Progress in integrated Late Triassic carbon isotopic stratigraphy of the Northern Calcareous Alps

    NASA Astrophysics Data System (ADS)

    Richoz, Sylvain; Krystyn, Leopold; Lein, Richard

    2015-04-01

    During the Late Triassic, despite new important originations a general decline in biodiversity was marked by a series of steps between the Carnian and the Rhaetian, with the T-J boundary event as final strike. The Reingraben Event and the Julian-Tuvalian boundary are two first massive turnovers; the Carnian-Norian boundary records a major vertebrate turnover, the early to middle Norian boundary comes up with a turnover in both the reefal and pelagic fauna and the most dramatic loss (70%) in biodiversity among Late Triassic molluscs. Around the Norian-Rhaetian boundary, the pelagic fauna of higher trophic level starts declining, whereas the reefs experience a blooming time. A refined stratigraphy and a construction of a well-calibrated carbon isotope reference curve are necessary to decipher between gradual environmental changes and abrupt or even catastrophic events during the Late Triassic. Improvement in the Upper Triassic d13Ccarb curve shows that after a gentle increase until the base of the Carnian, the early Carnian records three negative excursions of 2 to 3‰ amplitude. The two first excursions rebound to previous values, whereas the third negative excursion, at the Julian-Tuvalian boundary, is followed by a positive excursion up to +5‰. The remaining Upper Carnian displays stabile values around 2‰. The Carnian-Norian boundary interval is marked by a minor increase of less than 1‰. The Early to Middle Norian crisis is marked by a turning point from Early Norian slowly increasing carbon isotope values (up to 3.5‰) to gradually decreasing ones until 1.8‰ at the base of the Rhaetian. This Norian decrease display two accelerated steps, one in the middle Norian and the other one just after the Norian-Rhaetian Boundary. This last 1‰ decrease corresponds however to an important change in lithology. The values show then a small increase during the early Rhaetian, with a maximum in the middle Rhaetian (at 2.4‰). The isotopic record remains constant until the top of the Rhaetian with its significant negative shift identified in a number of marine sections in close proximity to the extinction event. The general stability of the curve even through the Norian-Rhaetian boundary crisis event describes a stable oceanic structure prior the mass extinction. From an isotopic point of view, only the two Lower Carnian excursions, the Early Late-Upper Carnian Boundary and the Triassic-Jurassic Boundary can be interpreted as events, whereas other biotic crises of the Late Triassic seem to have occurred during periods of gradual changes in the carbon isotopic composition of seawater.

  16. Partitioned transpression in the Triassic Aghdarband basin: evidence for a Cimmerian deformation in NE IRAN:

    NASA Astrophysics Data System (ADS)

    Zanchi, Andrea; Zanchetta, Stefano; Balini, Marco; Ghassemi, Mohammad Reza

    2014-05-01

    The Lower-Middle Triassic Aghdarband Basin, NE Iran, consists of a strongly deformed arc-related marine succession deposited along the southern margin of Eurasia (Turan domain) in a highly mobile tectonic context. The marine deposits are unconformably covered by Upper Triassic continental beds, marking the Cimmerian collision of Iran with Eurasia. The Aghdarband Basin is a key-area for the study of the Cimmerian events, as the Triassic units were severely folded and thrust short time after the collision and were unconformably covered by the gently deformed Middle Jurassic succession which seals the Cimmerian structures. The Triassic deposits form a north-verging thrust stack interacting with an important left-lateral strike-slip shear zone exposed in the northernmost part of the basin. Transpressional structures as strike-slip faults and vertical folds are here associated with high angle reverse faults forming intricate positive flower structures. Systematic asymmetry of major and parasitic folds, as well as their geometrical features indicate that they generated in a left-lateral transpressional regime roughly coeval to thrust imbrication to the south, as a consequence of a marked strain partitioning. Aim of this presentation is to describe in detail the deformational structures of the Aghdarband region, based on structural mapping and detailed original mesoscopic field analyses, resuming from the excellent work performed in the '70s by Ruttner (1991). Our work is focused on the pre mid-Jurassic structures which can be related to the final stages of the Cimmerian deformation resulting from the oblique collision of the Iranian microplate with the southern margin of Eurasia, the so-called Turan domain. We will finally discuss the kinematic significance of the Late Triassic oblique convergence zone of Aghdarband in the frame of strain partitioning in transpressional deformation. Structural weakness favouring strain partitioning can be related to inversion of syn-sedimentary faults active during the Triassic, resulting from the reactivation of previous Palaeozoic structural lineaments which characterize the Turan domain. A right-lateral reactivation of the main left-lateral fault zone followed during Neogene and Quaternary as a consequence of the Arabia collision to the south

  17. Spectral decomposition of time-scales in hyporheic exchange

    NASA Astrophysics Data System (ADS)

    Wörman, Anders; Riml, Joakim

    2015-04-01

    Hyporheic exchange of heat and solute mass in streams is manifested both in form of different exchange mechanisms and their associated distributions of residence times as well as the range of time-scales characterizing the forcing boundary conditions. A recently developed analytical technique separates the spectrum of time-scales and relates the forcing boundary fluctuations of heat and solute mass through a physical model of the hydrological transport to the response of heat and solute mass. This spectral decomposition can be done both for local (point-scale) observations in the hyporhiec zone itself as well as for transport processes on the watershed scale that can be considered 'well-behaved' in terms of knowledge of the forcing (input) quantities. This paper presents closed-form solutions in spectral form for the point-, reach- and watershed-scale and discusses their applicability to selected data of heat and solute concentration. We quantify the reliability and highlight the benefits of the spectral approach to different scenarios and, peculiarly, the importance for linking the periods in the spectral decomposition of the solute response to the distribution of transport times that arise due to the multitude of exchange mechanisms existing in a watershed. In a point-scale example the power spectra of in-stream temperature is related to the power spectrum of the temperature at a specific sediment depth by means of exact solutions of a physically based formulation of the vertical heat transport. It is shown that any frequency (?) of in-stream temperature fluctuation scales with the effective thermal diffusivity (?e) and the vertical separation distance between the pairs of temperature (É?) data as ? ? ?e/(2É?2), which implies a decreasing weight to higher frequencies (shorter periods) with depth. Similarly on the watershed-scale one can link the watershed dispersion to the damping of the concentration fluctuations in selected frequency intervals reflecting various environments responsible for the damping. The frequency-dependent parameters indicate that different environments dominate the response at different temporal scales.

  18. The Solar Activity in the Miocene Period In this Subthesis we study the solar activity in the Miocene (or Triassic)

    E-print Network

    The Solar Activity in the Miocene Period In this Subthesis we study the solar activity in the Miocene (or Triassic) period. Measurements of the thickness of the annual tree­rings of petrified trees in pre­historic times. Study of annual tree­ rings of 12 different petrified trees from the Miocene (or

  19. Triassic-Jurassic mass extinction as trigger for the Mesozoic radiation of crocodylomorphs.

    PubMed

    Toljagic, Olja; Butler, Richard J

    2013-06-23

    Pseudosuchia, one of the two main clades of Archosauria (Reptilia: Diapsida), suffered a major decline in lineage diversity during the Triassic-Jurassic (TJ) mass extinction (approx. 201 Ma). Crocodylomorpha, including living crocodilians and their extinct relatives, is the only group of pseudosuchians that survived into the Jurassic. We reassess changes in pseudosuchian morphological diversity (disparity) across this time interval, using considerably larger sample sizes than in previous analyses. Our results show that metrics of pseudosuchian disparity did not change significantly across the TJ boundary, contrasting with previous work suggesting low pseudosuchian disparity in the Early Jurassic following the TJ mass extinction. However, a significant shift in morphospace occupation between Late Triassic and Early Jurassic taxa is recognized, suggesting that the TJ extinction of many pseudosuchian lineages was followed by a major and geologically rapid adaptive radiation of crocodylomorphs. This marks the onset of the spectacularly successful evolutionary history of crocodylomorphs in Jurassic and Cretaceous ecosystems. PMID:23536443

  20. New time scale based k-epsilon model for near-wall turbulence

    Microsoft Academic Search

    Z. Yang; T. H. Shih

    1993-01-01

    A k-epsilon model is proposed for wall bonded turbulent flows. In this model, the eddy viscosity is characterized by a turbulent velocity scale and a turbulent time scale. The time scale is bounded from below by the Kolmogorov time scale. The dissipation equation is reformulated using this time scale and no singularity exists at the wall. The damping function used

  1. BeiDou Navigation Satellite System and its time scales

    NASA Astrophysics Data System (ADS)

    Han, Chunhao; Yang, Yuanxi; Cai, Zhiwu

    2011-08-01

    The development and current status of BeiDou Navigation Satellite System are briefly introduced. The definition and realization of the system time scales are described in detail. The BeiDou system time (BDT) is an internal and continuous time scale without leap seconds. It is maintained by the time and frequency system of the master station. The frequency accuracy of BDT is superior to 2 × 10-14 and its stability is better than 6 × 10-15/30 days. The satellite synchronization is realized by a two-way time transfer between the uplink stations and the satellite. The measurement uncertainty of satellite clock offsets is less than 2 ns. The BeiDou System has three modes of time services: radio determination satellite service (RDSS) one-way, RDSS two-way and radio navigation satellite service (RNSS) one-way. The uncertainty of the one-way time service is designed to be less than 50 ns, and that of the two-way time service is less than 10 ns. Finally, some coordinate tactics of UTC from the viewpoint of global navigation satellite systems (GNSS) are discussed. It would be helpful to stop the leap second, from our viewpoint, but to keep the UTC name, the continuity and the coordinate function unchanged.

  2. Iterative time series prediction and analysis by embedding and multiple time-scale decomposition networks

    NASA Astrophysics Data System (ADS)

    Hazarika, Neep; Lowe, David

    1997-04-01

    In this work we describe a method of estimating and characterizing appropriate data and model complexity in the context of long term iterated time series forecasting using embeddings and multiple time-scale decomposition techniques. An embedding of a signal is obtained which decouples multiple time scale effects such as seasonality and trend. The complexity and stability of networks are estimated and the performance of long term iteration is examined. The performance of the technique is tested using the real world time series problems of electricity load forecasting, and financial futures contracts.

  3. Differential force microscope for long time-scale biophysical measurements

    PubMed Central

    Choy, Jason L.; Parekh, Sapun H.; Chaudhuri, Ovijit; Liu, Allen P.; Bustamante, Carlos; Footer, Matthew J.; Theriot, Julie A.; Fletcher, Daniel A.

    2011-01-01

    Force microscopy techniques including optical trapping, magnetic tweezers, and atomic force microscopy (AFM) have facilitated quantification of forces and distances on the molecular scale. However, sensitivity and stability limitations have prevented the application of these techniques to biophysical systems that generate large forces over long times, such as actin filament networks. Growth of actin networks drives cellular shape change and generates nano-Newtons of force over time scales of minutes to hours, and consequently network growth properties have been difficult to study. Here, we present an AFM-based differential force microscope with integrated epifluorescence imaging in which two adjacent cantilevers on the same rigid support are used to provide increased measurement stability. We demonstrate 14 nm displacement control over measurement times of 3 hours and apply the instrument to quantify actin network growth in vitro under controlled loads. By measuring both network length and total network fluorescence simultaneously, we show that the average cross-sectional density of the growing network remains constant under static loads. The differential force microscope presented here provides a sensitive method for quantifying force and displacement with long time-scale stability that is useful for measurements of slow biophysical processes in whole cells or in reconstituted molecular systems in vitro. PMID:17477674

  4. Space-Time Scaling In The Atmospheric Boundary-Layer

    NASA Astrophysics Data System (ADS)

    Fitton, George; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2015-04-01

    We study the (multi-) scaling properties of the velocity time-increments as function a height (between 50 and 150m) using wind measurements from the well known Growian experiment. The Growian wind turbine experiment was a German Federal Ministry of Research and Technology's project that took place over the years 1983 to 1987. The experiment provides vertical wind profiles of wind speed and direction at 2.5Hz at 50, 75, 100, 125, and 150m. Velocity vectors are computed from the wind speed and direction allowing us to analyse the vertical velocity profiles in the so-called 'mixing-layer'. Plotting the scaling exponents of the structure functions of the time-increments of the velocity as a function of height shows that the space and time scalings of the velocity increments can be easily related to each other through their corresponding space-time fractal and multi-fractal properties. These properties are then confirmed for other datasets. Since the fractal and multi-fractal properties of a field are directly related to the extremes of field we are able to propose a high-order statistical model for wind extremes in the atmospheric boundary-layer (ABL). The same model can be used to generate synthetic ABL wind fields that can be useful for numerical model inflow conditions.

  5. Accuracy Assessment in rainfall upscaling in multiple time scales

    NASA Astrophysics Data System (ADS)

    Yu, H.; Wang, C.; Lin, Y.

    2008-12-01

    Long-term hydrologic parameters, e.g. annual precipitations, are usually used to represent the general hydrologic characteristics in a region. Recently, the analysis of the impact of climate change to hydrological patterns primarily relies on the measurement and/or the estimations in long time scales, e.g. year. Under the general condition of the prevalence of short-term measurements, therefore, it is important to understand the accuracy of upscaling for the long-term estimations of hydrologic parameters. This study applies spatiotemporal geostatistical method to analyze and discuss the accuracy of precipitation upscaling in Taiwan under the different time scales, and also quantifies the uncertainty in the upscaled long-term precipitations. In this study, two space-time upscaling approaches developed by Bayesian Maximum Entropy method (BME) are presented 1) UM1: data aggregation followed by BME estimation and 2) UM2: BME estimation followed by aggregation. The investigation and comparison are also implemented to assess the performance of the rainfall estimations in multiple time scales in Taiwan by the two upscaling. Keywords: upscaling, geostatistics, BME, uncertainty analysis

  6. Forecast Solar Irradiance Variability on Multiple Time Scales

    NASA Astrophysics Data System (ADS)

    Tobiska, W.; Schatten, K.; Pryor, W.; Bouwer, D.; Detman, T.; Woods, T.; Pankratz, C.; Eparvier, F. G.; Viereck, R.; Puga, L.

    2001-12-01

    We report on research that is improving current solar spectral irradiance forecasting capabilities. In particular, the portion of the solar spectrum chosen is that applicable to operational atmospheric density specifications related to low-Earth orbiting satellites. There are six time scales of solar variability for which we are developing forecast algorithms. These include 1-72 hour time scales associated with large flares, 3-14 day Earth-facing solar disk irradiances, 14-28 day solar far side events, 1-6 month active region evolution, 1/2-11 year solar cycle variability, and 1-5 solar cycle climatological specification. Many current algorithms use the first-order assumption of solar irradiance persistence over specific time scales. The basis for forecasting on each of these time derives from a different source. For example, the nowcast, current 24-hour period uses the method of Viereck et al. (2001) where EUV (proxy) = 0.6 MgII (daily) + 0.4 MgII (29-day avg). The 72-hour forecast is generated with an autoregressive technique to determine the trend of the next 3 days. The 14-day forecast simply uses the previous data from 14-days ago to the present epoch. The 28-day forecast uses the previous 28-days of data convolved with a triangular function to reduce noise. The 6-month forecast uses the previous 6-months of data convolved with a 30-day wide triangular function. The 11-year forecast has used the previous 11-years of data similarly convolved. The 55-year forecast uses the mean value of the previous 5 solar cycles. Improvements to these algorithms are demonstrated that will reduce the uncertainty and quantify the variability in each forecast time scale, as these algorithms are used in forecasting solar irradiances for space system operations. Viereck , R., et al., Geophys. Res. Lett., 28, 1343-1346, 2001.

  7. A Triassic Fauna from Madagascar, Including Early Dinosaurs.

    PubMed

    Flynn; Parrish; Rakotosamimanana; Simpson; Whatley; Wyss

    1999-10-22

    The discovery of a Middle to Late Triassic ( approximately 225 to 230 million years old) terrestrial vertebrate fauna from Madagascar is reported. This fauna documents a temporal interval not well represented by continental vertebrate assemblages elsewhere in the world. It contains two new prosauropod dinosaurs, representing some of the earliest dinosaur occurrences known globally. This assemblage provides information about the poorly understood transition to the dinosaur-dominated faunas of the latest Triassic. PMID:10531059

  8. Lowermost Triassic (Griesbachian) microbial bindstone-cementstone facies, southwest Japan

    Microsoft Academic Search

    Hiroyoshi Sano; Koichi Nakashima

    1997-01-01

    Summary  On the basis of the lithostratigraphy and microscopic characters, the paper describes the facies interpretation of the upper\\u000a Upper Permian (Changhsingian) and Lower Triassic (Griesbachian to Spathian) carbonates of southwest Japan, with a focus upon\\u000a the lowermost Triassic (Griesbachian) microbial bindstone-cementstone. We emphasize the significant sediment-binding and stabilizing\\u000a agencies of microbes chiefly of cyanobacteria along with the syndepositional cementation for

  9. A possible endogonaceous fungus from the Triassic of Antarctica

    E-print Network

    Stubblefield, Sara P.; Taylor, Thomas N.; Seymour, Roland L.

    1987-01-05

    Department of Botany, The Ohio State University, Columbus, Ohio 43210 A possible endogonaceous fungus has recently been discovered in a silicified matrix from the Triassic of Antarctica. Material was collected from the Fremouw Peak Formation near Fre...-mouw Peak in the Beardmore Glacier region of Antarctica in conjunction with the Byrd Polar Research Center at The Ohio State University. The matrix is early-middle Triassic (Collinson et al., 1980). Specimens bear collection numbers 17,442-17,451 in The Ohio...

  10. A Possible Endogonaceous Fungus from the Triassic of Antarctica

    E-print Network

    Stubblefield, Sara P.; Taylor, Thomas N.; Seymour, Roland L.

    1987-11-01

    Department of Botany, The Ohio State University, Columbus, Ohio 43210 A possible endogonaceous fungus has recently been discovered in a silicified matrix from the Triassic of Antarctica. Material was collected from the Fremouw Peak Formation near Fre...-mouw Peak in the Beardmore Glacier region of Antarctica in conjunction with the Byrd Polar Research Center at The Ohio State University. The matrix is early-middle Triassic (Collinson et al., 1980). Specimens bear collection numbers 17,442-17,451 in The Ohio...

  11. Thermal lens measurements in liquids on a submicrosecond time scale

    SciTech Connect

    Isak, S. J.; Komorowski, S. J.; Merrow, C. N.; Poston, P. E.; Eyring, E. M.

    1989-03-01

    The use of the thermal lens method is shown to be quite suitable for kinetic studies of quenching on a submicrosecond time scale. The lower limit of time resolution that can be achieved is determined by the acoustic transit time, /tau//sub /ital a//, in the medium. A thermal lens signal with a 100-ns time constant due to the quenched triplet state of benzophenone is readily measured. The thermal lens method is superior to the photoacoustic (PA) method in the breadth of the accessible time range, and in the significantly fewer measurements required to obtain accurate data, including no requirement for a reference sample; it is also less sensitive to geometrical and laser power requirements than is the PA method.

  12. Time-average based on scaling law in anomalous diffusions

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Joo

    2015-05-01

    To solve the obscureness in measurement brought about from the weak ergodicity breaking appeared in anomalous diffusions, we have suggested the time-averaged mean squared displacement (MSD) /line{? 2 (? )}? with an integral interval depending linearly on the lag time ?. For the continuous time random walk describing a subdiffusive behavior, we have found that /line{? 2 (? )}? ˜ ? ? like that of the ensemble-averaged MSD, which makes it be possible to measure the proper exponent values through time-average in experiments like a single molecule tracking. Also, we have found that it has originated from the scaling nature of the MSD at an aging time in anomalous diffusion and confirmed them through numerical results of the other microscopic non-Markovian model showing subdiffusions and superdiffusions with the origin of memory enhancement.

  13. Time scale of diffusion in molecular and cellular biology

    NASA Astrophysics Data System (ADS)

    Holcman, D.; Schuss, Z.

    2014-05-01

    Diffusion is the driver of critical biological processes in cellular and molecular biology. The diverse temporal scales of cellular function are determined by vastly diverse spatial scales in most biophysical processes. The latter are due, among others, to small binding sites inside or on the cell membrane or to narrow passages between large cellular compartments. The great disparity in scales is at the root of the difficulty in quantifying cell function from molecular dynamics and from simulations. The coarse-grained time scale of cellular function is determined from molecular diffusion by the mean first passage time of molecular Brownian motion to a small targets or through narrow passages. The narrow escape theory (NET) concerns this issue. The NET is ubiquitous in molecular and cellular biology and is manifested, among others, in chemical reactions, in the calculation of the effective diffusion coefficient of receptors diffusing on a neuronal cell membrane strewn with obstacles, in the quantification of the early steps of viral trafficking, in the regulation of diffusion between the mother and daughter cells during cell division, and many other cases. Brownian trajectories can represent the motion of a molecule, a protein, an ion in solution, a receptor in a cell or on its membrane, and many other biochemical processes. The small target can represent a binding site or an ionic channel, a hidden active site embedded in a complex protein structure, a receptor for a neurotransmitter on the membrane of a neuron, and so on. The mean time to attach to a receptor or activator determines diffusion fluxes that are key regulators of cell function. This review describes physical models of various subcellular microdomains, in which the NET coarse-grains the molecular scale to a higher cellular-level, thus clarifying the role of cell geometry in determining subcellular function.

  14. Separation of equilibration time scales in the gradient expansion

    NASA Astrophysics Data System (ADS)

    Garbrecht, Björn; Konstandin, Thomas

    2009-04-01

    We study thermalization by applying gradient expansion to the Kadanoff-Baym equations of the two-particle-irreducible effective action to two-loop in a theory with Dirac fermions coupled to scalars. In addition to those chemical potentials that equilibrate in the on-shell limit, we identify modes that are conserved in this approximation, but which relax when off-shell effects are taken into account. This implies that chemical equilibration does not require higher loop contributions to the effective action and is compatible with the gradient expansion. We explicitly calculate the damping time scales of both, on- and off-shell, chemical equilibration rates. It is shown that off-shell equilibration is suppressed by the thermal width of the particles in the plasma, which explains the separation of on- and off-shell chemical equilibration time scales.

  15. Extending the astronomical (polarity) time scale into the Miocene

    Microsoft Academic Search

    F. J. Hilgen; W. Krijgsman; C. G. Langereis; L. J. Lourens; A. Santarelli; W. J. Zachariasse

    1995-01-01

    An astronomical time scale is presented for the late Miocene based on the correlation of characteristic sedimentary cycle patterns in marine sections in the Mediterranean to the 65°N summer insolation curve of La90[1,2] with present-day values for the dynamical ellipticity of the Earth and tidal dissipation by the moon. This correlation yields ages for all sedimentary cycles and hence also

  16. Control systems on regular time scales and their differential rings

    Microsoft Academic Search

    Zbigniew Bartosiewicz; Ülle Kotta; Ewa Pawluszewicz; Malgorzata Wyrwas

    2011-01-01

    The paper describes an algebraic construction of the inversive differential ring, associated with a nonlinear control system,\\u000a defined on a nonhomogeneous but regular time scale. The ring of meromorphic functions in system variables is constructed under\\u000a the assumption that the system is submersive, and equipped with three operators (delta- and nabla-derivatives, and the forward\\u000a shift operator) whose properties are studied.

  17. Output feedback control of nonlinear two-time-scale systems

    Microsoft Academic Search

    Panagiotis D. Christofides

    1997-01-01

    This work focuses on dynamic output feedback control of a class of nonlinear singularly perturbed systems. A nonlinear two-time-scale output feedback controller is synthesized which guarantees stability and enforces output tracking in the closed-loop system, provided that the singular perturbation parameter is sufficiently small. The proposed controller is successfully tested on a chemical process modeled by a nonlinear singularly perturbed

  18. Solar Irradiance Variations on Active Region Time Scales

    NASA Technical Reports Server (NTRS)

    Labonte, B. J. (editor); Chapman, G. A. (editor); Hudson, H. S. (editor); Willson, R. C. (editor)

    1984-01-01

    The variations of the total solar irradiance is an important tool for studying the Sun, thanks to the development of very precise sensors such as the ACRIM instrument on board the Solar Maximum Mission. The largest variations of the total irradiance occur on time scales of a few days are caused by solar active regions, especially sunspots. Efforts were made to describe the active region effects on total and spectral irradiance.

  19. The post-Triassic sedimentary cover of Tunisia: Seismic sequences and structure

    NASA Astrophysics Data System (ADS)

    Bobier, C.; Viguier, C.; Chaari, A.; Chine, A.

    1991-09-01

    A series of geological cross sections based on data from the new geological map of Tunisia coupled with stratigraphic and structural studies indicate that a folded, post-Triassic sedimentary cover was separated from the basement by a decollement zone located in Triassic evaporitic deposits. Four depositional basins were formed during the Triassic and Liassic in an extensional regime, on a presumably thinned continental crust. Geological fieldwork, studies of metamorphic grade and gravimetric and magnetic surveys indicate that their depocentres shifted with time from basin to basin, finally resulting in today's Tellian and Tunisian troughs to the north, Gafsa Trough to the west of Gabes and the Tuniso-Libyan Trough to the east. Subsidence in the latter trough commenced at the end of the Cretaceous and is still continuing today. There are four well-defined seismic stratigraphic sequences comprising Mesozoic and Cenozoic sedimentary rocks, each with distinctive lithoseismic characteristics. We display the distribution and structure of these seismic sequences in a series of cross sections. In addition, we note that the regional tectonic style of Tunisia has been greatly influenced by a conjugate strike-slip fault system. The role of wrench faulting has been well-documented in the Kasserine and other areas by detailed structural studies.

  20. Biogenic Calcium Phosphate Transformation in Soils over Millennium Time Scales

    SciTech Connect

    Sato, S.; Neves, E; Solomon, D; Liang, B; Lehmann, J

    2009-01-01

    Changes in bioavailability of phosphorus (P) during pedogenesis and ecosystem development have been shown for geogenic calcium phosphate (Ca-P). However, very little is known about long-term changes of biogenic Ca-P in soil. Long-term transformation characteristics of biogenic Ca-P were examined using anthropogenic soils along a chronosequence from centennial to millennial time scales. Phosphorus fractionation of Anthrosols resulted in overall consistency with the Walker and Syers model of geogenic Ca-P transformation during pedogenesis. The biogenic Ca-P (e.g., animal and fish bones) disappeared to 3% of total P within the first ca. 2,000 years of soil development. This change concurred with increases in P adsorbed on metal-oxides surfaces, organic P, and occluded P at different pedogenic time. Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy revealed that the crystalline and therefore thermodynamically most stable biogenic Ca-P was transformed into more soluble forms of Ca-P over time. While crystalline hydroxyapatite (34% of total P) dominated Ca-P species after about 600-1,000 years, {Beta}-tricalcium phosphate increased to 16% of total P after 900-1,100 years, after which both Ca-P species disappeared. Iron-associated P was observable concurrently with Ca-P disappearance. Soluble P and organic P determined by XANES maintained relatively constant (58-65%) across the time scale studied. Conclusions - Disappearance of crystalline biogenic Ca-P on a time scale of a few thousand years appears to be ten times faster than that of geogenic Ca-P.

  1. Is there a break in scaling on centennial time scale in Holocene temperature records?

    NASA Astrophysics Data System (ADS)

    Nilsen, Tine; Rypdal, Kristoffer; Fredriksen, Hege-Beate

    2015-04-01

    A variety of paleoclimatic records have been used to study scaling properties of past climate, including ice core paleotemperature records and multi-proxy reconstructions. Records extending further back in time than the Holocene are divided into glacial/interglacial segments before analysis. The methods used to infer the scaling include the power spectral density (Lomb-Scargle periodogram and standard periodogram), detrended fluctuation analysis, wavelet variance analysis and the Haar fluctuation function. All the methods have individual strengths, weaknesses, uncertainties and biases, and for this reason it is useful to compare results from different methods when possible. Proxy-based reconstructions have limited spatial and temporal coverage, and must be used and interpreted with great care due to uncertainties. By elaborating on physical mechanisms for the actual climate fluctuations seen in the paleoclimatic temperature records as well as uncertainties in both data and methods, we demonstrate the possible pitfalls that may lead to the conclusion that the variability in temperature time series can be separated into different scaling regimes. Categorizing the Earth's surface temperature variability into a «macroweather» and "climate" regime has little or no practical meaning since the different components in the climate system are connected and interact on all time scales. Our most important result is that a break between two different scaling regimes at time scales around one century cannot be identified in Holocene climate. We do, however, observe departures from scaling, which can be attributed to variability such as a single internal quasi-periodic oscillation, an externally forced trend, or a combination of factors. If two scaling regimes are claimed to be present in one single time series, both regimes must be persistent. We show that the limited temporal resolution/length of the records significantly lowers the confidence for such persistence. A total of six Holocene ice core paleotemperature records were studied, (GRIP, GISP2 and NGRIP from Greenland, EPICA, Vostok and Taylor Dome from Antarctica). For all time series the estimated scaling exponent ? is between 0.1 and 0.3 up to millennial time scales, where a deviation is observed and a seemingly higher value of ? is inferred on longer time scales. The Holocene ice core records have by Lovejoy et al. (2012) been claimed to be exceptionally stable, compared to other proxy records such as marine sediment cores. Such a statement should be followed by a discussion about different types of proxy reconstructions and climate conditions. This presentation highlights that care should be taken when comparing the climate of continental land covered by ice, with a marine sediment record representing an oceanographically dynamic area. Different proxies are representative of different environmental variables, and the reconstructions are created to give a general paleoclimatic overview of a certain area, and are in that manner only blurred snapshots of the past climate.

  2. Modeling of streamflow processes at different time scales

    NASA Astrophysics Data System (ADS)

    Bartolini, Paolo; Salas, Jose D.

    1993-08-01

    The analysis and modeling of streamflow processes has attracted the attention of water resources specialists for several decades. A number of models have been suggested in the past for representing seasonal and annual streamflow processes. The topic addressed in this paper centers around the compatibility of stochastic models of streamflow at different time scales. More specifically, given a model for monthly flows, the models for the processes obtained by aggregation, i.e., models for bimonthly, quarterly, etc., time scales, are derived. Likewise, parameter space and covariance properties of such derived processes as well as the relationship of such properties of different time scales are given. These concepts are applied to modeling streamflow of the Niger River. The developments are restricted to the family of periodic autoregressive moving average (PARMA) processes. For instance, it was found that monthly flows based on the PARMA(2, 1) process leads to PARMA(2, 2) bimonthly flows and stationary ARMA(2, 2) annual flows. Furthermore, applications to modeling the Niger River flows suggest that one can reproduce the seasonal and annual second-order statistics without using disaggregation if PARMA models are used for modeling the seasonal flows.

  3. Scaling brain size, keeping timing: evolutionary preservation of brain rhythms.

    PubMed

    Buzsáki, György; Logothetis, Nikos; Singer, Wolf

    2013-10-30

    Despite the several-thousand-fold increase of brain volume during the course of mammalian evolution, the hierarchy of brain oscillations remains remarkably preserved, allowing for multiple-time-scale communication within and across neuronal networks at approximately the same speed, irrespective of brain size. Deployment of large-diameter axons of long-range neurons could be a key factor in the preserved time management in growing brains. We discuss the consequences of such preserved network constellation in mental disease, drug discovery, and interventional therapies. PMID:24183025

  4. Petrogenesis and geodynamic implications of the Mid-Triassic lavas from East Kunlun, northern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Li, Xiaowei; Huang, Xiongfei; Luo, Mingfei; Dong, Guochen; Mo, Xuanxue

    2015-06-01

    Lying in the northern margin of the Tibetan Plateau, the East Kunlun Orogenic Belt (EKOB) is characterized by widespread of the late Permian to Late Triassic magmatic rocks. In order to better understand magma genesis and evolution during the waning stage of the Paleo-Tethyan oceanic subduction and subsequent collision, we present zircon U-Pb dating and Lu-Hf isotopes, whole-rock major and trace elements, and Sr-Nd isotope data for the Triassic volcanic lavas in the Haishigou area of the EKOB, northern Tibet. Lithologically, the Haishigou volcanic lavas are mainly composed of dacites and rhyolites. The LA-ICP-MS zircon U-Pb analyses for rhyolites have shown that the Haishigou volcanic rocks formed during the Middle Triassic with ages of ca. 244-245 Ma. The Haishigou volcanic lavas actually belong to part of the Middle Triassic Naocangjiangou Formation, rather than the Late Triassic Elashan Formation. Geochemically, Haishigou volcanic lavas have SiO2 = 60.31-76.19 wt% and K2O = 2.60-4.18 wt%, placing them in high-K calc-alkaline series. These lavas are characterized by enrichment in some large-ion lithophile elements (e.g., Rb, K and Pb) and light rare earth elements and depletion in some high field strength elements (e.g., Nb, Ta, and Ti), with geochemical affinities to those rocks forming in a continental or an oceanic arc setting. All the volcanic rocks exhibit high initial 87Sr/86Sr ratios (0.70614-0.70841) and moderately negative ?Nd(t) values (-5.9 to -4.3) that imply a continental rather than oceanic type magma source. The rhyolites in the Haishigou volcanics exhibit moderately negative to slightly positive ?Hf(t) values (-4.2 to 1.4). Combined with their zircon Hf two-stage model ages of 1187-1538 Ma and whole-rock Nd two-stage model ages of 1.37-1.38 Ga, it can be inferred that the crustal growth of East Kunlun occurred during the Mesoproterozoic, making them similar in age to the lower crust metamorphic basement beneath the EKOB (i.e., the Xiaomiao Group). We suggest that the Haishigou dacites were generated by partial melting of the mafic lower crust beneath the EKOB with addition of a mantle-derived mafic component and that the rhyolites were produced by fractional crystallization from a dacitic parent. Taking into account the Late Permian to Triassic geological record from the EKOB and surrounding regions, we argue that the Middle Triassic volcanic rocks in the Haishigou area erupted during the northward subduction of the Paleo-Tethyan oceanic plate. Consequently, the timing of closure of the Paleo-Tethyan Ocean just south of the EKOB is no earlier than the Middle Triassic.

  5. Two-time-scale population evolution on a singular landscape

    NASA Astrophysics Data System (ADS)

    Xu, Song; Jiao, Shuyun; Jiang, Pengyao; Ao, Ping

    2014-01-01

    Under the effect of strong genetic drift, it is highly probable to observe gene fixation or gene loss in a population, shown by singular peaks on a potential landscape. The genetic drift-induced noise gives rise to two-time-scale diffusion dynamics on the bipeaked landscape. We find that the logarithmically divergent (singular) peaks do not necessarily imply infinite escape times or biological fixations by iterating the Wright-Fisher model and approximating the average escape time. Our analytical results under weak mutation and weak selection extend Kramers's escape time formula to models with B (Beta) function-like equilibrium distributions and overcome constraints in previous methods. The constructed landscape provides a coherent description for the bistable system, supports the quantitative analysis of bipeaked dynamics, and generates mathematical insights for understanding the boundary behaviors of the diffusion model.

  6. Two-time-scale population evolution on a singular landscape.

    PubMed

    Xu, Song; Jiao, Shuyun; Jiang, Pengyao; Ao, Ping

    2014-01-01

    Under the effect of strong genetic drift, it is highly probable to observe gene fixation or gene loss in a population, shown by singular peaks on a potential landscape. The genetic drift-induced noise gives rise to two-time-scale diffusion dynamics on the bipeaked landscape. We find that the logarithmically divergent (singular) peaks do not necessarily imply infinite escape times or biological fixations by iterating the Wright-Fisher model and approximating the average escape time. Our analytical results under weak mutation and weak selection extend Kramers's escape time formula to models with B (Beta) function-like equilibrium distributions and overcome constraints in previous methods. The constructed landscape provides a coherent description for the bistable system, supports the quantitative analysis of bipeaked dynamics, and generates mathematical insights for understanding the boundary behaviors of the diffusion model. PMID:24580274

  7. Life crises on land across the Permian-Triassic boundary in South China

    NASA Astrophysics Data System (ADS)

    Peng, Yuanqiao; Shi, G. R.

    2009-02-01

    The western Guizhou and eastern Yunnan area of southwest China commands a unique and significant position globally in the study of Permian-Triassic boundary (PTB) events as it contains well and continuously exposed PTB sections of marine, non-marine and marginal-marine origin in the same area. By using a range of high-resolution stratigraphic methods including biostratigraphy, eventostratigraphy, chronostratigraphy and chemostratigraphy, not only are the non-marine PTB sections correlated with their marine counterparts in the study area with high-resolution, the non-marine PTB sections of the study area can also be aligned with the PTB Global Stratotype Section and Point (GSSP) at Meishan in eastern China. Plant megafossils ("megaplants") in the study area indicate a major loss in abundance and diversity across the PTB, and no coal beds and/or seams have been found in the non-marine Lower Triassic although they are very common in the non-marine Upper Permian. The megaplants, however, did not disappear consistently across the whole area, with some elements of the Late Permian Cathaysian Gigantopteris flora surviving the PTB mass extinction and locally even extending up to the Lower Triassic. Palynomorphs exhibit a similar temporal pattern characterized by a protracted stepwise decrease from fern-dominated spores in the Late Permian to pteridosperm and gymnosperm-dominated pollen in the Early Triassic, which was however punctuated by an accelerated loss in both abundance and diversity across the PTB. Contemporaneous with the PTB crisis in the study area was the peculiar prevalence and dominance of some fungi and/or algae species. The temporal patterns of megaplants and palynomorphs across the PTB in the study area are consistent with the regional trends of plant changes in South China, which also show a long-term decrease in species diversity from the Late Permian Wuchiapingian through the Changhsingian to the earliest Triassic, with about 48% and 77% losses of species occurring respectively in the end-Wuchiapingian and end-Changhsingian. Such consistent patterns, at both local and regional scales, contradict the hypothesis of a regional isochronous extinction of vegetation across the PTB, and hence call into question the notion that the end-Permian mass extinction was a one-hit disaster. Instead, the data from the study area and South China appears more consistent with a scenario that invokes climate change as the main driver for the observed land vegetation changes across the PTB in South China.

  8. Optimal detection using bilinear time-frequency and time-scale representations

    Microsoft Academic Search

    A. M. Sayeed; D. L. Jones

    1995-01-01

    Bilinear time-frequency representations (TFRs) and time-scale representations (TSRs) are potentially very useful for detecting a nonstationary signal in the presence of nonstationary noise or interference. As quadratic signal representations, they are promising for situations in which the optimal detector is a quadratic function of the observations. All existing time-frequency formulations of quadratic detection either implement classical optimal detectors equivalently in

  9. Broadband time-domain-reflectometry dielectric spectroscopy using variable-time-scale sampling

    Microsoft Academic Search

    N. E. Hager

    1994-01-01

    Methods for increasing the bandwidth of time-domain-reflectometry (TDR) dielectric spectroscopy using variable-time-scale sampling are presented. Consecutive segments of the TDR transient are sampled with increasing time increments and the entire transient transformed into the frequency domain using a running Laplace transform. Instrumentation artifacts are identified and controlled by examining reflected transients for stray artifacts prior to transformation, either on individual

  10. Terrestrial Waters and Sea Level Variations on Interannual Time Scale

    NASA Technical Reports Server (NTRS)

    Llovel, W.; Becker, M.; Cazenave, A.; Jevrejeva, S.; Alkama, R.; Decharme, B.; Douville, H.; Ablain, M.; Beckley, B.

    2011-01-01

    On decadal to multi-decadal time scales, thermal expansion of sea waters and land ice loss are the main contributors to sea level variations. However, modification of the terrestrial water cycle due to climate variability and direct anthropogenic forcing may also affect sea level. For the past decades, variations in land water storage and corresponding effects on sea level cannot be directly estimated from observations because these are almost non-existent at global continental scale. However, global hydrological models developed for atmospheric and climatic studies can be used for estimating total water storage. For the recent years (since mid-2002), terrestrial water storage change can be directly estimated from observations of the GRACE space gravimetry mission. In this study, we analyse the interannual variability of total land water storage, and investigate its contribution to mean sea level variability at interannual time scale. We consider three different periods that, each, depend on data availability: (1) GRACE era (2003-2009), (2) 1993-2003 and (3) 1955-1995. For the GRACE era (period 1), change in land water storage is estimated using different GRACE products over the 33 largest river basins worldwide. For periods 2 and 3, we use outputs from the ISBA-TRIP (Interactions between Soil, Biosphere, and Atmosphere-Total Runoff Integrating Pathways) global hydrological model. For each time span, we compare change in land water storage (expressed in sea level equivalent) to observed mean sea level, either from satellite altimetry (periods 1 and 2) or tide gauge records (period 3). For each data set and each time span, a trend has been removed as we focus on the interannual variability. We show that whatever the period considered, interannual variability of the mean sea level is essentially explained by interannual fluctuations in land water storage, with the largest contributions arising from tropical river basins.

  11. The Luoping biota: exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction.

    PubMed

    Hu, Shi-xue; Zhang, Qi-yue; Chen, Zhong-Qiang; Zhou, Chang-yong; Lü, Tao; Xie, Tao; Wen, Wen; Huang, Jin-yuan; Benton, Michael J

    2011-08-01

    The timing and nature of biotic recovery from the devastating end-Permian mass extinction (252 Ma) are much debated. New studies in South China suggest that complex marine ecosystems did not become re-established until the middle-late Anisian (Middle Triassic), much later than had been proposed by some. The recently discovered exceptionally preserved Luoping biota from the Anisian Stage of the Middle Triassic, Yunnan Province and southwest China shows this final stage of community assembly on the continental shelf. The fossil assemblage is a mixture of marine animals, including abundant lightly sclerotized arthropods, associated with fishes, marine reptiles, bivalves, gastropods, belemnoids, ammonoids, echinoderms, brachiopods, conodonts and foraminifers, as well as plants and rare arthropods from nearby land. In some ways, the Luoping biota rebuilt the framework of the pre-extinction latest Permian marine ecosystem, but it differed too in profound ways. New trophic levels were introduced, most notably among top predators in the form of the diverse marine reptiles that had no evident analogues in the Late Permian. The Luoping biota is one of the most diverse Triassic marine fossil Lagerstätten in the world, providing a new and early window on recovery and radiation of Triassic marine ecosystems some 10 Myr after the end-Permian mass extinction. PMID:21183583

  12. Heterogenous scaling in interevent time of on-line bookmarking

    E-print Network

    Wang, Peng; Yeung, Chi Ho; Wang, Bing-Hong

    2010-01-01

    In this paper, we study the statistical properties of bookmarking behaviors in Delicious.com. We find that the interevent time distributions of bookmarking decays powerlike as interevent time increases at both individual and population level. Remarkably, we observe a significant change in the exponent when interevent time increases from intra-day to inter-day range. In addition, dependence of exponent on individual Activity is found to be different in the two ranges. These results suggests that mechanisms driving human actions are different in intra- and inter-day range. Instead of monotonically increasing with Activity, we find that inter-day exponent peaks at value around 3. We further show that less active users are more likely to resemble poisson process in bookmarking. Based on the temporal-preference model, preliminary explanations for this dependence have been given . Finally, a universal behavior in inter-day scale is observed by considering the rescaled variable.

  13. Decay of surface nanostructures via long-time-scale dynamics

    SciTech Connect

    Voter, A.F.; Stanciu, N.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors have developed a new approach for extending the time scale of molecular dynamics simulations. For infrequent-event systems, the category that includes most diffusive events in the solid phase, this hyperdynamics method can extend the simulation time by a few orders of magnitude compared to direct molecular dynamics. The trajectory is run on a potential surface that has been biased to raise the energy in the potential basins without affecting the transition state region. The method is described and applied to surface and bulk diffusion processes, achieving microsecond and millisecond simulation times. The authors have also developed a new parallel computing method that is efficient for small system sizes. The combination of the hyperdynamics with this parallel replica dynamics looks promising as a general materials simulation tool.

  14. Multiple-Time Scaling and Universal Behavior of the Earthquake Interevent Time Distribution

    SciTech Connect

    Bottiglieri, M.; Godano, C.; Lippiello, E. [Department of Environmental Sciences and CNISM, Second University of Naples, Caserta (Italy); Arcangelis, L. de [IfB, ETH, Schafmattstr. 6, 8093 Zuerich (Switzerland) and Department of Information Engineering and CNISM, Second University of Naples, Aversa (Italy)

    2010-04-16

    The interevent time distribution characterizes the temporal occurrence in seismic catalogs. Universal scaling properties of this distribution have been evidenced for entire catalogs and seismic sequences. Recently, these universal features have been questioned and some criticisms have been raised. We investigate the existence of universal scaling properties by analyzing a Californian catalog and by means of numerical simulations of an epidemic-type model. We show that the interevent time distribution exhibits a universal behavior over the entire temporal range if four characteristic times are taken into account. The above analysis allows us to identify the scaling form leading to universal behavior and explains the observed deviations. Furthermore, it provides a tool to identify the dependence on the mainshock magnitude of the c parameter that fixes the onset of the power law decay in the Omori law.

  15. Many roads to synchrony: Natural time scales and their algorithms

    NASA Astrophysics Data System (ADS)

    James, Ryan G.; Mahoney, John R.; Ellison, Christopher J.; Crutchfield, James P.

    2014-04-01

    We consider two important time scales—the Markov and cryptic orders—that monitor how an observer synchronizes to a finitary stochastic process. We show how to compute these orders exactly and that they are most efficiently calculated from the ?-machine, a process's minimal unifilar model. Surprisingly, though the Markov order is a basic concept from stochastic process theory, it is not a probabilistic property of a process. Rather, it is a topological property and, moreover, it is not computable from any finite-state model other than the ?-machine. Via an exhaustive survey, we close by demonstrating that infinite Markov and infinite cryptic orders are a dominant feature in the space of finite-memory processes. We draw out the roles played in statistical mechanical spin systems by these two complementary length scales.

  16. Geomorphological stability of Permo-Triassic albitized profiles - case study of the Montseny-Guilleries High (NE Iberia)

    NASA Astrophysics Data System (ADS)

    Parcerisa, D.; Casas, L.; Franke, C.; Gomez-Gras, D.; Lacasa, G.; Nunez, J. A.; Thiry, M.

    2010-05-01

    Massif paleoalteration profiles (? 200 m) occur in the upper parts of the Montseny-Guilleries High (NE Catalan Coastal Ranges). The profiles consist of hard albitized-chloritized-hematized facies in the lower part and softer kaolinized-hematized facies in the upper part of the section. Preliminary paleomagnetic data show Triassic ages for both, the albitized and the kaolinized parts, and point to a surficial formation altered under oxidising conditions. Similar paleoalteration profiles have already been described and dated to Triassic ages elsewhere in Europe [Schmitt, 1992; Ricordel et al., 2007; Parcerisa et al., 2009]. These Permian-Triassic alterations are following a succession of different mineral transformations from the top to the base of the profile: 1) Red facies are defined by an increase in the amount and size of haematite crystals leading to the red colour of the rocks. The increase on haematite content is pervasively affecting the whole rock and is accompanied by the kaolinitization of the feldspars. 2) Pink facies: here, the granite shows an uniform pink colouration, which is mainly due to the albitization of the primary Ca-bearing plagioclases, accompanied by a precipitation of minute haematite, sericite, and calcite crystals inside the albite. Additionally primary biotite is fully chloritized. The pink granites are much more resistant to the present-day weathering than the "unaltered" facies at the base of the profile. 3) Spotted facies is characterized by a partial alteration of the rock, which caused a pink-screened aspect to the rock. The alteration developed along the fractures and is less well developed or absent in the non-fractured zones. In the pink-screened facies, the plagioclases are partially albitized and contain numerous hematite inclusions. Biotites are usually almost entirely chloritized. 4) Unaltered facies: These granites are coloured white to greyish, containing plagioclase and K-feldspar that do not show any trace of albitization. Biotites are not or weakly chloritized. However, these "unaltered" (or primary) granites are strongly weathered into granite boulders embedded in grus by the present-day climatic conditions. The maturest paleoprofiles occur at the northern part of the Catalan Coastal Ranges (i.e. the Montseny-Guilleries High) where the Variscan basement remained exposed during Triassic times. Towards the South the profiles progressively disappear and Triassic sediments acquire their maximum thickness here. The alteration profiles are related with the Permo-Triassic paleosurface still outcroping on wide areas [Gómez-Gras and Ferrer, 1999]. They are partially covered by Triassic fluvial sandstones (Buntsandstein facies) in the South [Gómez-Gras, 1993] and by Palaeocene alluvial conglomerates in the West [Anadón et al., 1979]. The Triassic paleosurface shows a remarkable stability successively outcropping during Mesozoic and Tertiary times, the pre-Tertiary exhumation and even the present day weathering affected very little these albitized profiles. The hardness and thus preservation of the Triassic paleosurface is mainly related to the albitization. The albitized granites are entirely lacking anorthitic plagioclase, which is much more sensitive to chemo-mechanical weathering. Development of albite and additional chloritization of the primary biotite crystals render the rocks much more resistant to weathering and erosion. This stability is particularly well expressed in case of the Montseny-Guilleries High, which is limited by a high fault scarp at the south-eastern margin. The albitized top of the scarp shows remarkably hard fresh rocks, whereas the base of the scarp (formed of primary, non-albitized facies) is deeply weathered into gruss. This is causing much smother landscape reliefs in the valleys and thalwegs. Since a long time the remarkable persistence of the Triassic paleosurface expressed in the Paleozoic massifs has been highlighted by geomorphologists. Only recently we could draw the link of the paleosurface preservation to its albitisation [

  17. Time scales in the context of general relativity.

    PubMed

    Guinot, Bernard

    2011-10-28

    Towards 1967, the accuracy of caesium frequency standards reached such a level that the relativistic effect could not be ignored anymore. Corrections began to be applied for the gravitational frequency shift and for distant time comparisons. However, these corrections were not applied to an explicit theoretical framework. Only in 1991 did the International Astronomical Union provide metrics (then improved in 2000) for a definition of space-time coordinates in reference systems centred at the barycentre of the Solar System and at the centre of mass of the Earth. In these systems, the temporal coordinates (coordinate times) can be realized on the basis of one of them, the International Atomic Time (TAI), which is itself a realized time scale. The definition and the role of TAI in this context will be recalled. There remain controversies regarding the name to be given to the unit of coordinate times and to other quantities appearing in the theory. However, the idea that astrometry and celestial mechanics should adopt the usual metrological rules is progressing, together with the use of the International System of Units, among astronomers. PMID:21930569

  18. Time scale algorithms for an inhomogeneous group of atomic clocks

    NASA Technical Reports Server (NTRS)

    Jacques, C.; Boulanger, J.-S.; Douglas, R. J.; Morris, D.; Cundy, S.; Lam, H. F.

    1993-01-01

    Through the past 17 years, the time scale requirements at the National Research Council (NRC) have been met by the unsteered output of its primary laboratory cesium clocks, supplemented by hydrogen masers when short-term stability better than 2 x 10(exp -12)tau(sup -1/2) has been required. NRC now operates three primary laboratory cesium clocks, three hydrogen masers, and two commercial cesium clocks. NRC has been using ensemble averages for internal purposes for the past several years, and has a realtime algorithm operating on the outputs of its high-resolution (2 x 10(exp -13) s at 1 s) phase comparators. The slow frequency drift of the hydrogen masers has presented difficulties in incorporating their short-term stability into the ensemble average, while retaining the long-term stability of the laboratory cesium frequency standards. We report on this work on algorithms for an inhomogeneous ensemble of atomic clocks, and on our initial work on time scale algorithms that could incorporate frequency calibrations at NRC from the next generation of Zacharias fountain cesium frequency standards having frequency accuracies that might surpass 10(exp -15), or from single-trapped-ion frequency standards (Ba+, Sr+,...) with even higher potential accuracies. The requirements for redundancy in all the elements (including the algorithms) of an inhomogeneous ensemble that would give a robust real-time output of the algorithms are presented and discussed.

  19. Formation processes and time scales for meteorite parent bodies

    NASA Technical Reports Server (NTRS)

    Weidenschilling, S. J.

    1988-01-01

    The transition from small particles suspended in the solar nebula to the planetesimals (asteroids) that became the parent bodies of meteorites is examined. Planetesimals probably grew by coagulation of grain aggregates that collided due to different rates of settling and drag-induced orbital decay. Their growth was accompanied by radial transport of solids, possibly sufficient to deplete the primordial mass in the asteroid zone, but with relatively little mixing. The formation of asteroid-sized planetesimals was probably rapid, on a time scale less than 1 Myr.

  20. Paleoenvironmental significance of carbonate microbialites from the uppermost Rhaetian (latest Triassic) southwestern United Kingdom

    NASA Astrophysics Data System (ADS)

    Ibarra, Y.; Corsetti, F. A.; Greene, S. E.; Bottjer, D. J.

    2013-12-01

    Several upper Triassic sections of the southwestern United Kingdom contain a laterally extensive (2,000 km2), thin (~20 cm) unit of carbonate microbialites known regionally as the Cotham Marble. The microbialites occur as discrete mounds that range from about 0.5 to 2 meters in diameter and are internally composed of alternating dendritic and laminated mesofabrics. The dendritic portions are composed of microspar/micrite, contain abundant putative pyrite coated filamentous microfossils, and have elevated total organic carbon (TOC) relative to the interstitial fill. Here, we highlight two very striking features of the Cotham Marble microbialites which offer clues to local paleoenvironmental conditions across the end-Triassic mass extinction interval: (1) the microbialites contain extensive laterally continuous fabrics with mm-scale laminae that are represented in samples separated by at least 10 km and (2) the microbialites preserve fine, sub-mm scale details of microbial mat branching patterns. The proliferation and preservation of largely undisturbed, laterally continuous fabrics and delicate microbial mat textures indicate the microbialites were lithified very quickly likely from growth in waters with an anomalously high saturation state with respect to calcium carbonate. High saturation state possibly resulted from accelerated weathering conditions due to the emplacement of the Central Atlantic Magmatic Providence (CAMP). The fine-grained, dominantly micritic nature of the microbialites bears a strong textural resemblance to their Precambrian counterparts in contrast to the coarse-grained fabrics of modern marine microbialites. Such fine-grained textures are rare in Phanerozoic marine microbialites but are known to occur during other mass extinction episodes. Therefore, the Cotham Marble microbialites could indicate a brief return to microbial carbonate deposition as a consequence of the end-Triassic mass extinction.

  1. Late Permian to Late Triassic palaeomagnetic data from Iran: constraints on the migration of the Iranian block through the Tethyan Ocean and initial destruction of Pangaea

    NASA Astrophysics Data System (ADS)

    Besse, J.; Torcq, F.; Gallet, Y.; Ricou, L. E.; Krystyn, L.; Saidi, A.

    1998-10-01

    A palaeomagnetic study of Late Permian to early Jurassic rocks from the Alborz and Sanandaj-Sirjan zones in Iran and a compilation of selected palaeopoles from the Carboniferous to the present provide an updated history of the motion of the Iranian block within the Tethys Ocean. The Iran assemblage, part of Gondwana during the Palaeozoic, rifted away by the end of the Permian. We ascertain the southern-hemisphere palaeoposition of Iran at that time using magnetostratigraphy and show that it was situated close to Arabia, near to its relative position today. A northward transit of this block during the Triassic is shown, with an estimated expansion rate of the Neotethyan ridge of 100-140 km Myr-1. The northward convergence with respect to Eurasia ended during the Ladinian (Middle Triassic), and is marked by a collision in the northern hemisphere with the Turan platform, which was the southern margin of the Eurasian continent at that time. No north-south component of shortening is evidenced north of Iran afterwards. An analysis of the declinations from the Late Permian to the present shows different, large rotations, emphasizing the important tectonic phases suffered since the Triassic. Finally, we propose palaeomagnetic reconstructions of the Tethys area during the Late Permian and the Late Triassic, showing that the Palaeotethys Ocean was narrower than previously thought, and did not widen its gate to the Panthalassa before the Triassic period.

  2. Evidence for prosauropod dinosaur gastroliths in the Bull Run Formation (Upper Triassic, Norian) of Virginia

    USGS Publications Warehouse

    Weems, R.E.; Culp, M.J.; Wings, O.

    2007-01-01

    Definitive criteria for distinguishing gastroliths from sedimentary clasts are lacking for many depositional settings, and many reported occurrences of gastroliths either cannot be verified or have been refuted. We discuss four occurrences of gastrolith-like stones (category 6 exoliths) not found within skeletal remains from the Upper Triassic Bull Run Formation of northern Virginia, USA. Despite their lack of obvious skeletal association, the most parsimonious explanation for several characteristics of these stones is their prolonged residence in the gastric mills of large animals. These characteristics include 1) typical gastrolith microscopic surface texture, 2) evidence of pervasive surface wear on many of these stones that has secondarily removed variable amounts of thick weathering rinds typically found on these stones, and 3) a width/length-ratio modal peak for these stones that is more strongly developed than in any population of fluvial or fanglomerate stones of any age found in this region. When taken together, these properties of the stones can be explained most parsimoniously by animal ingestion and gastric-mill abrasion. The size of these stones indicates the animals that swallowed them were large, and the best candidate is a prosauropod dinosaur, possibly an ancestor of the Early Jurassic gastrolith-producing prosauropod Massospondylus or Ammosaurus. Skeletal evidence for Upper Triassic prosauropods is lacking in the Newark Supergroup basins; footprints (Agrestipus hottoni and Eubrontes isp.) from the Bull Run Formation in the Culpeper basin previously ascribed to prosauropods are now known to be underprints (Brachychirotherium parvum) of an aetosaur and underprints (Kayentapus minor) of a ceratosaur. The absence of prosauropod skeletal remains or footprints in all but the uppermost (upper Rhaetian) Triassic rocks of the Newark Supergroup is puzzling because prosauropod remains are abundant elsewhere in the world in Upper Triassic (Carnian, Norian, and lower Rhaetian) continental strata. The apparent scarcity of prosauropods in Upper Triassic strata of the Newark Supergroup is interpreted as an artifact of ecological partitioning, created by the habitat range and dietary preferences of phytosaurs and by the preservational biases at that time within the lithofacies of the Newark Supergroup basins.

  3. Permo-Triassic collisional orogenesis and transition to intraplate sinistral shear in southeastern Mongolia

    NASA Astrophysics Data System (ADS)

    Webb, L. E.; Taylor, J. P.; Heumann, M. J.; Johnson, C. L.; Stypula, M.; Kylander-Clark, A. R.

    2011-12-01

    Southeastern Mongolia is part of a vast accretionary complex involving Paleozoic arc terranes of the Altaid tectonic collage that collided with North China during closure of the Paleo-Asian Ocean. The region also records a complex history of post-collisional polyphase Triassic-Quaternary intraplate deformation. We present new 40Ar/39Ar and U/Pb titanite data that place temporal constraints on the evolution of collisional orogenesis and the transition to intraplate deformation in southeastern Mongolia where highly deformed and metamorphosed Lower-Upper Permian turbidite successions mark final closure of a remnant ocean basin between the Paleozoic arc terranes and the North China block. At Nomgon, the turbidite sequences are structurally bound by deformed metasediments, including marbles, of higher strain and metamorphic grade. 40Ar/39Ar step heating analyses of hornblende from a granitoid and white mica from muscovite schist along the SW and S margins of the turbidites yield plateau ages of 274 and 273 Ma, respectively. White mica from mylonitic rocks along the NW margin of the Nomgon block yielded a 40Ar/39Ar spectrum with a loss profile and 234 Ma weighted mean age. At Bulgan Uul, an offset correlative of the Nomgon section, the transition from marine to terrestrial sedimentation is cross-cut by an intermediate-mafic dike swarm for which hornblende yielded a 245 Ma 40Ar/39Ar plateau age. To the north and structurally below a carbonate klippe, hornblende from the metamorphosed and boudinaged equivalent of the dike gave a 40Ar/39Ar 227 Ma weighted mean age. Biotite from the same boudin and its host gneiss both yield complicated spectra but are consistent with Late Triassic metamorphism and deformation. Late Triassic metamorphic tectonites at Tavan Har record evidence for partial melting at amphibolite-facies conditions and multiple generations of intrusions. Field, petrographic, and U/Pb zircon analyses indicate that the protoliths of the metamorphic tectonites are Paleozoic volcanic and sedimentary sequences. U/Pb titanite data from amphibolites and amphibolite-facies gneisses yield an older population c. 274 Ma, and two younger populations at 244 and 224 Ma. The latter is consistent with 40Ar/39Ar data that constrain the timing of amphibolite-facies sinistral shear in the East Gobi Fault Zone (EGFZ). Taken together and integrated with ongoing studies, these data along strike of the EGFZ suggest that Permian collisional orogenesis in SE Mongolia continued until the Early Triassic and that the transition to intraplate sinistral shear along the NE-trending EGFZ occurred by the Late Triassic (Carnian), dissecting the closed oceanic basin.

  4. 1. Geologic time scale 2. Local stratigraphic column ( Cambrian Flathead -f , Cambrian Wolsey -w , Cambrian

    E-print Network

    Polly, David

    for each period of geologic time (e.g. Cambrian ­ west to east transgression; Late Jurassic ­ widespread that you know the geologic time scale, at least to the period level. Knowing the time scale is essential

  5. Climatically driven biogeographic provinces of Late Triassic tropical Pangea

    PubMed Central

    Whiteside, Jessica H.; Grogan, Danielle S.; Olsen, Paul E.; Kent, Dennis V.

    2011-01-01

    Although continents were coalesced into the single landmass Pangea, Late Triassic terrestrial tetrapod assemblages are surprisingly provincial. In eastern North America, we show that assemblages dominated by traversodont cynodonts are restricted to a humid 6° equatorial swath that persisted for over 20 million years characterized by “semiprecessional” (approximately 10,000-y) climatic fluctuations reflected in stable carbon isotopes and sedimentary facies in lacustrine strata. More arid regions from 5–20°N preserve procolophonid-dominated faunal assemblages associated with a much stronger expression of approximately 20,000-y climatic cycles. In the absence of geographic barriers, we hypothesize that these variations in the climatic expression of astronomical forcing produced latitudinal climatic zones that sorted terrestrial vertebrate taxa, perhaps by excretory physiology, into distinct biogeographic provinces tracking latitude, not geographic position, as the proto-North American plate translated northward. Although the early Mesozoic is usually assumed to be characterized by globally distributed land animal communities due to of a lack of geographic barriers, strong provinciality was actually the norm, and nearly global communities were present only after times of massive ecological disruptions. PMID:21571639

  6. Seismicity in the Triassic Deep River Basin, North Carolina

    NASA Astrophysics Data System (ADS)

    Portner, D. E.; Wagner, L. S.; Fouch, M. J.; James, D. E.; Roman, D. C.; Golden, S.

    2013-12-01

    The Deep River Basin in central North Carolina is one of a series of Triassic rift basins along the east coast called the Newark Supergroup. Although the east coast lies on a passive plate margin, there is recorded seismicity within all of the coastal states, much of which is attributed to boundary faults of the Newark Supergroup basins. However, this seismicity is conspicuously absent around the Deep River Basin and most of North Carolina east of the Appalachian Mountains. In March 2012 we installed a 12 station broadband seismic network surrounding the Sanford Sub-Basin of the Deep River Basin to measure unrecorded seismicity. Through fifteen months of data collection, we have confidently detected and located more than 160 low magnitude seismic events within the array. However, the event locations cluster in four locations - three of which are near local rock quarries and one is near an unidentified anthropic feature. Further, these events consistently occur between the hours of 9am and 6pm local time, Monday through Friday indicating that they are anthropogenic. The Deep River Basin is one of the most likely places east of the Appalachian Mountains in North Carolina to be seismically active, yet we have measured no natural seismicity. Using receiver functions and known origins of the local seismic events we will be examining the crustal structure beneath the Deep River Basin to explain the conspicuous lack of local seismic activity.

  7. Mid-infrared diffuse reflection on ultrafast time scales.

    PubMed

    Brauns, Eric B

    2014-01-01

    This paper describes an instrument capable of studying diffuse reflection of mid-infrared (mid-IR) photons on ultrafast time scales. Femtosecond mid-IR pulses are generated by difference frequency mixing the output of an optical parametric amplifier that is pumped using a regeneratively amplified Ti:Sapphire laser. Time resolution is achieved by up-converting the diffusely reflected photons with pulses from the Ti:Sapphire oscillator. Experiments were performed on a series of powdered KBr samples containing varying amounts of carbon black. The results suggest that diffusely reflected mid-IR photons fall into two distinct categories. A small fraction of the photons travel relatively long effective path lengths (1.3-2.3 mm), while the majority traverse a much shorter distance (0.2-0.05 mm). PMID:24405947

  8. Transport relaxation time and length scales in turbulent suspensions

    E-print Network

    P. Claudin; F. Charru; B. Andreotti

    2010-11-03

    We show that in a turbulent flow transporting suspended sediment, the unsaturated sediment flux $q(x,t)$ can be described by a first-order relaxation equation. From a mode analysis of the advection-diffusion equation for the particle concentration, the relaxation length and time scales of the dominant mode are shown to be the deposition length $H U/V_{\\rm fall}$ and deposition time $H/V_{\\rm fall}$, where $H$ is the flow depth, $U$ the mean flow velocity and $V_{\\rm fall}$ the sediment settling velocity. This result is expected to be particularly relevant for the case of sediment transport in slowly varying flows, where the flux is never far from saturation. Predictions are shown to be in quantitative agreement with flume experiments, for both net erosion and net deposition situations.

  9. Reusable Launch Vehicle Control in Multiple Time Scale Sliding Modes

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri

    1999-01-01

    A reusable launch vehicle control problem during ascent is addressed via multiple-time scaled continuous sliding mode control. The proposed sliding mode controller utilizes a two-loop structure and provides robust, de-coupled tracking of both orientation angle command profiles and angular rate command profiles in the presence of bounded external disturbances and plant uncertainties. Sliding mode control causes the angular rate and orientation angle tracking error dynamics to be constrained to linear, de-coupled, homogeneous, and vector valued differential equations with desired eigenvalues placement. The dual-time scale sliding mode controller was designed for the X-33 technology demonstration sub-orbital launch vehicle in the launch mode. 6DOF simulation results show that the designed controller provides robust, accurate, de-coupled tracking of the orientation angle command profiles in presence of external disturbances and vehicle inertia uncertainties. It creates possibility to operate the X-33 vehicle in an aircraft-like mode with reduced pre-launch adjustment of the control system.

  10. Reusable Launch Vehicle Control In Multiple Time Scale Sliding Modes

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri; Hall, Charles; Jackson, Mark

    2000-01-01

    A reusable launch vehicle control problem during ascent is addressed via multiple-time scaled continuous sliding mode control. The proposed sliding mode controller utilizes a two-loop structure and provides robust, de-coupled tracking of both orientation angle command profiles and angular rate command profiles in the presence of bounded external disturbances and plant uncertainties. Sliding mode control causes the angular rate and orientation angle tracking error dynamics to be constrained to linear, de-coupled, homogeneous, and vector valued differential equations with desired eigenvalues placement. Overall stability of a two-loop control system is addressed. An optimal control allocation algorithm is designed that allocates torque commands into end-effector deflection commands, which are executed by the actuators. The dual-time scale sliding mode controller was designed for the X-33 technology demonstration sub-orbital launch vehicle in the launch mode. Simulation results show that the designed controller provides robust, accurate, de-coupled tracking of the orientation angle command profiles in presence of external disturbances and vehicle inertia uncertainties. This is a significant advancement in performance over that achieved with linear, gain scheduled control systems currently being used for launch vehicles.

  11. Dynamic response of materials on sub-nanosecond time scales

    NASA Astrophysics Data System (ADS)

    Swift, Damian

    2004-11-01

    During the past few years, substantial progress has been made in developing experimental techniques capable of investigating the response of materials to dynamic loading on nanosecond time scales and shorter, with multiple diagnostics probing different aspects of the behavior. These relatively short time scales are scientifically interesting because plastic flow and phase changes in common materials with simple crystal structures - such as iron - may be suppressed, allowing unusual states to be induced and the dynamics of plasticity and polymorphism to be explored. Loading by laser ablation can be particularly convenient. The TRIDENT laser has been used to impart shocks and isentropic compression waves from ˜1 to 200 GPa in a range of elements and alloys, with diagnostics including surface velocimetry (line-imaging VISAR), surface displacement (framed area imaging), x-ray diffraction (single crystal and polycrystal), ellipsometry, and Raman spectroscopy. A major motivation has been the study of the properties of beryllium under conditions relevant to the ICF fuel capsule: magnetically-driven shock and isentropic compression shots at Z were used to investigate the equation of state and shock melting characteristics, complemented by laser ablation experiments to investigate plasticity and heterogeneous response. These results will help to constrain acceptable tolerances on manufacturing, and possible loading paths, for ICF ignition experiments at the National Ignition Facility. Laser-based techniques are being developed further for future material dynamics experiments at NIF, where it should be possible to obtain high quality data on strength and phase changes up to at least 1 TPa.

  12. Nonlinear Dynamics of Extended Hydrologic Systems over long time scales

    NASA Astrophysics Data System (ADS)

    Lall, Upmanu

    2014-05-01

    We often view our knowledge of hydrology and hence of nature as intransient, at least over the time scales over which we study processes we wish to predict and understand. Over the last few decades, this assumption has come under question, largely because of the vocal expression of a changing climate, but also the recurrent demonstration of significant land use change, both of which significantly affect the boundary conditions for terrestrial hydrology that is our forte. Most recently, the concepts of hydromorphology and social hydrology have entered the discussion, and the notion that climate and hydrology influence human action, which in turn shapes hydrology, is being recognized. Finally, as a field, we seem to be coming to the conclusion that the hydrologic system is an open system, whose boundaries evolve in time, and that the hydrologic system, at many scales, has a profound effect on the systems that drive it -- whether they be the ecological and climatic systems, or the social system. What a mess! Complexity! Unpredictability! At a certain level of abstraction, one can consider the evolution of these coupled systems with nonlinear feedbacks and ask what types of questions are relevant in terms of such a coupled evolution? What are their implications at the planetary scale? What are their implications for a subsistence farmer in an arid landscape who may under external influence achieve a new transient hydro-ecological equilibrium? What are the implications for the economy and power of nations? In this talk, I will try to raise some of these questions and also provide some examples with very simple dynamical systems that suggest ways of thinking about some practical issues of feedback across climate, hydrology and human behavior.

  13. Detrital zircon provenance of the Late Triassic Songpan-Ganzi complex: Sedimentary record of collision of the North and South China blocks

    USGS Publications Warehouse

    Weislogel, A.L.; Graham, S.A.; Chang, E.Z.; Wooden, J.L.; Gehrels, G.E.; Yang, H.

    2006-01-01

    Using detrital zircon geochronology, turbidite deposystems fed from distinct sediment sources can be distinguished within the Songpan-Ganzi complex, a collapsed Middle to Late Triassic turbidite basin of central China. A southern Songpan-Ganzi deposystem initially was sourced solely by erosion of the Qinling-Dabie orogen during early Late Triassic time, then by Qinling-Dabie orogen, North China block, and South China block sources during middle to late Late Triassic time. A northern Songpan-Ganzi system was sourced by erosion of the Qinling-Dabie orogen and the North China block throughout its deposition. These separate deposystems were later tectonically amalgamated to form one complex and then uplifted as the eastern Tibet Plateau. ?? 2006 Geological Society of America.

  14. Provenance analysis and tectonic setting of the Triassic clastic deposits in Western Chukotka, Northeast Russia

    Microsoft Academic Search

    M. I. Tuchkova; S. Sokolov; I. R. Kravchenko-Berezhnoy

    2009-01-01

    The study area is part of the Anyui subterrane of the Chukotka microplate, a key element in the evolution of the Amerasia Basin, located in Western Chukotka, Northeast Russia. The subterrane contains variably deformed, folded and cleaved rhythmic Triassic terrigenous deposits which represent the youngest stage of widespread marine deposition which form three different complexes: Lower-Middle Triassic, Upper Triassic (Carnian)

  15. Palaeomagnetism and magnetostratigraphy of the Permian and Triassic of Spitsbergen: a review of progress and challenges

    E-print Network

    1 Palaeomagnetism and magnetostratigraphy of the Permian and Triassic of Spitsbergen: a review.hounslow@lancs.ac.uk. Abstract Permian and Triassic sediments from Svalbard provide a testing ground for evaluating concepts of partial remagnetization of these sediments. Permian and Triassic palaeomagnetic poles from Spitsbergen

  16. Instructions for use Kerogen morphology and geochemistry at the Permian-Triassic transition in the

    E-print Network

    Tsunogai, Urumu

    Instructions for use #12;1 Kerogen morphology and geochemistry at the Permian-Triassic transition organic matter (kerogens) are conducted on the end-Permian to earliest Triassic sediments in the Meishan for the Permian - Triassic boundary (PTB). Most of kerogens in the Meishan section are mainly composed of marine

  17. Magnetic polarity stratigraphy and paleolatitude of the Triassic^Jurassic Blomidon Formation in the Fundy basin

    E-print Network

    Olsen, Paul E.

    Magnetic polarity stratigraphy and paleolatitude of the Triassic^Jurassic Blomidon Formation] characterized the Triassic as perhaps the most arid period of the Phanerozoic, citing evidence for widespread,5] and the apparent expan- sion of deserts in the Triassic and Early Jurassic to an extent not since repeated [6

  18. Evidence for Triassic salt domes in the Tunisian Atlas from gravity and geological data

    Microsoft Academic Search

    Chokri Jallouli; Mongi Chikhaoui; Ahmed Braham; Mohamed Moncef Turki; Kevin Mickus; Ramdhane Benassi

    2005-01-01

    Detailed gravity data were analyzed to constrain two controversial geological models of evaporitic structures within the Triassic diapiric zone (Triassic massifs of Jebel Debadib and Ben Gasseur) of the northern Tunisian Atlas. Based on surface observations, two geological models have been used to explain the origin of the Triassic evaporitic bodies: (1) salt dome\\/diapiric structure or (2) a “salt glacier”.

  19. Critical time scales for advection-diffusion-reaction processes

    NASA Astrophysics Data System (ADS)

    Ellery, Adam J.; Simpson, Matthew J.; McCue, Scott W.; Baker, Ruth E.

    2012-04-01

    The concept of local accumulation time (LAT) was introduced by Berezhkovskii and co-workers to give a finite measure of the time required for the transient solution of a reaction-diffusion equation to approach the steady-state solution [A. M. Berezhkovskii, C. Sample, and S. Y. Shvartsman, Biophys. J.BIOJAU0006-349510.1016/j.bpj.2010.07.045 99, L59 (2010); A. M. Berezhkovskii, C. Sample, and S. Y. Shvartsman, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.83.051906 83, 051906 (2011)]. Such a measure is referred to as a critical time. Here, we show that LAT is, in fact, identical to the concept of mean action time (MAT) that was first introduced by McNabb [A. McNabb and G. C. Wake, IMA J. Appl. Math.IJAMDM0272-496010.1093/imamat/47.2.193 47, 193 (1991)]. Although McNabb's initial argument was motivated by considering the mean particle lifetime (MPLT) for a linear death process, he applied the ideas to study diffusion. We extend the work of these authors by deriving expressions for the MAT for a general one-dimensional linear advection-diffusion-reaction problem. Using a combination of continuum and discrete approaches, we show that MAT and MPLT are equivalent for certain uniform-to-uniform transitions; these results provide a practical interpretation for MAT by directly linking the stochastic microscopic processes to a meaningful macroscopic time scale. We find that for more general transitions, the equivalence between MAT and MPLT does not hold. Unlike other critical time definitions, we show that it is possible to evaluate the MAT without solving the underlying partial differential equation (pde). This makes MAT a simple and attractive quantity for practical situations. Finally, our work explores the accuracy of certain approximations derived using MAT, showing that useful approximations for nonlinear kinetic processes can be obtained, again without treating the governing pde directly.

  20. Kinematic restoration of the Mediterranean region since the Triassic

    NASA Astrophysics Data System (ADS)

    van Hinsbergen, Douwe; Torsvik, Trond; Matenco, Liviu; Schmid, Stefan; Maffione, Marco; Spakman, Wim

    2014-05-01

    The Mediterranean region is one of the most complexly deformed areas in the world and its tectonic evolution has been instrumental in the development of numerous fundamental geological principles and geodynamic concepts. Reconstructions of the Mediterranean region invariably demonstrated that the area had a complex paleogeography with ribbon continents or micro-plates and narrow, elongated ocean basins systems in Mesozoic time. A western and northern ocean basin system was genetically related to the Atlantic Ocean, opened in Jurassic time and is known as the Alpine Tethys Ocean. A southern and eastern basin system was genetically related to the Neotethys domain located between Gondwana and Eurasia and - in the Mediterranean realm - opened in Triassic to Jurassic times. Continental domains of variable size within and between these ocean systems rifted away from Eurasia or Africa. This mosaic of pieces of continental and oceanic lithosphere became consumed by a complex configuration of subduction zones that accommodated convergence between the African and Eurasian plates since middle Jurassic times. Since Oligocene time, the overriding plate above subduction zones throughout the Mediterranean region became extended, locally leading to formation of new ocean floor, as a result of roll-back of subducted slab segments, culminating in todays complex and strongly curved configuration of subduction zones and slab segments. An area such as the tectonically complex Mediterranean invites attempt to kinematic restoration, and various reconstructions are already available. However, by now such reconstructions are no more merely a translation of - frequently qualitative - geological data into a quantitative description of surface evolution: with the advent of 3-dimensional numerical modeling tools that can be kinematically driven by plate reconstructions, they become critical input for attempts to integrate surface evolution into mantle dynamics. An increasingly widely used platform for kinematic reconstructions is the freely available GPlates plate kinematic reconstruction software (http://www.gplates.org). We provide the first fully quantitatively described GPlates-based kinematic reconstruction of the Mediterranean region back to Triassic time. Classic plate reconstructions assume plate rigidity, and motion concentrated along discrete plate boundaries. Convergence between Africa-Europe plate boundary in the Mediterranean region is, however, associated with regionally distributed deformation. In this reconstruction, we attempt to restore this distributed deformation, which in practice means that we allow for polygons to change shape and area over time. This reconstruction may (i) be used as input for numerical models that aim to constrain the geodynamic evolution of (parts of) the Mediterranean history, (ii) allow comparing relative tectonic motions of the Mediterranean region to the mantle using mantle reference frames, and (iii) provide regional kinematic context for future geological studies. Upon final publication, all shape and rotation files of this reconstruction will be made publically available, which may serve as a platform for further improvement when new constraints demand so, or when the reader wishes to test different tectonic scenarios.

  1. Modelling Time and Length Scales of Scour Around a Pipeline

    NASA Astrophysics Data System (ADS)

    Smith, H. D.; Foster, D. L.

    2002-12-01

    The scour and burial of submarine objects is an area of interest for engineers, oceanographers and military personnel. Given the limited availability of field observations, there exists a need to accurately describe the hydrodynamics and sediment response around an obstacle using numerical models. In this presentation, we will compare observations of submarine pipeline scour with model predictions. The research presented here uses the computational fluid dynamics (CFD) model FLOW-3D. FLOW-3D, developed by Flow Science in Santa Fe, NM, is a 3-dimensional finite-difference model that solves the Navier-Stokes and continuity equations. Using the Volume of Fluid (VOF) technique, FLOW-3D is able to resolve fluid-fluid and fluid-air interfaces. The FAVOR technique allows for complex geometry to be resolved with rectangular grids. FLOW-3D uses a bulk transport method to describe sediment transport and feedback to the hydrodynamic solver is accomplished by morphology evolution and fluid viscosity due to sediment suspension. Previous investigations by the authors have shown FLOW-3D to well-predict the hydrodynamics around five static scoured bed profiles and a stationary pipeline (``Modelling of Flow Around a Cylinder Over a Scoured Bed,'' submit to Journal of Waterway, Port, Coastal, and Ocean Engineering). Following experiments performed by Mao (1986, Dissertation, Technical University of Denmark), we will be performing model-data comparisons of length and time scales for scour around a pipeline. Preliminary investigations with LES and k-? closure schemes have shown that the model predicts shorter time scales in scour hole development than that observed by Mao. Predicted time and length scales of scour hole development are shown to be a function of turbulence closure scheme, grain size, and hydrodynamic forcing. Subsequent investigations consider variable wave-current flow regimes and object burial. This investigation will allow us to identify different regimes for the scour process based on dimensionless parameters such as the Reynolds number, the Keulegan-Carpenter number, and the sediment mobility number. This research is sponsored by the Office of Naval Research - Mine Burial Program.

  2. Scale Analysis of Convective Activity on Titan: Is the Surface Setting the Time Scale?

    NASA Astrophysics Data System (ADS)

    Ingersoll, A. P.; Roe, H. G.; Schaller, E. L.; Brown, M. E.

    2005-08-01

    A fundamental number for convective activity is the time tau needed to re-humidify the atmosphere. This is M/E, where M is the mass of condensate per unit area (50 kg/m2 for Earth) and E is the evaporation rate (1.5 m of liquid water/yr). Alternately, tau is ML/F, where L is the latent heat of vaporization and F is the surface heat flux (125 W/m2 for Earth). With these numbers, tau = 12 days for Earth. This number also controls the time that a parcel spends in the descending branch of the Hadley cell, since the parcel must radiate away the heat of vaporization that it gained in the ascending branch. Tropical convective activity fluctuates on comparable time scales. Equatorial wave disturbances propagate to the west with a period of 4-5 days (Holton, 2004, p. 375). The equatorial intraseasonal oscillation, also known as the Madden-Julian oscillation (MJO), propagates to the east on a timescale of 30-60 days (Holton, 2004, p. 385). These bracket the time scale tau. Other oscillations like El Nino Southern Oscillation (ENSO) and the quasi-biennial oscillation (QBO) involve the oceans and the stratosphere, and are less relevant to the timescales of tropical convection. The value of tau for Titan is hundreds of times greater than for Earth, because the surface heat flux is much less and the latent heat content is about the same as on Earth. The polar cloud outbreaks at intervals of months around Titan's southern summer solstice are then a puzzle, as are the short-term variations of mid-latitude clouds observed after the solstice. One possibility (Roe et al., 2005, submitted; Schaller et al., 2005, submitted) is that the clouds originate from eruptions at the surface, which is controlling the variability of the atmosphere.

  3. Lethally hot temperatures during the Early Triassic greenhouse.

    PubMed

    Sun, Yadong; Joachimski, Michael M; Wignall, Paul B; Yan, Chunbo; Chen, Yanlong; Jiang, Haishui; Wang, Lina; Lai, Xulong

    2012-10-19

    Global warming is widely regarded to have played a contributing role in numerous past biotic crises. Here, we show that the end-Permian mass extinction coincided with a rapid temperature rise to exceptionally high values in the Early Triassic that were inimical to life in equatorial latitudes and suppressed ecosystem recovery. This was manifested in the loss of calcareous algae, the near-absence of fish in equatorial Tethys, and the dominance of small taxa of invertebrates during the thermal maxima. High temperatures drove most Early Triassic plants and animals out of equatorial terrestrial ecosystems and probably were a major cause of the end-Smithian crisis. PMID:23087244

  4. Redescription of Bellerophon bittneri (Gastropoda: Triassic) from Wyoming.

    USGS Publications Warehouse

    Yochelson, E.L.; Boyd, D.W.; Wardlaw, B.

    1985-01-01

    Bellerophon bittneri Newell and Kummel is an Early Triassic bellerophontacean from the Dinwoody Formation in the Wind River Mountains. The available type material consists of one fair, but incomplete, external mold, which resembles a Bellerophon but is actually a Retispira. After repeated search, additional specimens were found at one locality in the southern Wind River Range of Wyoming; Retispira bittneri is redescribed from this new material. Like other Triassic bellerophontaceans, there is nothing unusual about the species apart from occurrence in the Mesozoic; it is clearly congeneric with Permian Retispira from underlying rocks. -Authors

  5. Response time of large-scale electrochromic devices

    SciTech Connect

    Randin, J.P. [ASULAB S.A., Neuchatel (Switzerland)

    1990-12-31

    The studies related to electrochromic phenomena performed in the seventies were mainly aimed at the development of information displays. Such applications require small electrode sizes, i.e. with active surface areas of between about 0.01 to 10 cm{sup 2}. The development of large information devices and chiefly smart windows require much larger switching areas. This paper deals with the influence of increasing the active surface area on the response time. The latter depends on both properties of the cell components (transparent conducting layer, electrochromic film, electrolyte and counter electrode) and structure of the cell (size, shape, gap, resistivity of the busbar). Experimental devices were constructed with given components and cell geometry. The effect of a series resistance arisen mainly from the cell size was investigated and explained by the effect of the additional series resistance on the response time of a diffusion-controlled process. The study indicates that the scaling-up of WO{sub 3} devices will be limited by an increase of the response time with increasing active area.

  6. Variations in solar Lyman alpha irradiance on short time scales

    NASA Technical Reports Server (NTRS)

    Pap, J. M.

    1992-01-01

    Variations in solar UV irradiance at Lyman alpha are studied on short time scales (from days to months) after removing the long-term changes over the solar cycle. The SME/Lyman alpha irradiance is estimated from various solar indices using linear regression analysis. In order to study the nonlinear effects, Lyman alpha irradiance is modeled with a 5th-degree polynomial as well. It is shown that the full-disk equivalent width of the He line at 1083 nm, which is used as a proxy for the plages and active network, can best reproduce the changes observed in Lyman alpha. Approximately 72 percent of the solar-activity-related changes in Lyman alpha irradiance arise from plages and the network. The network contribution is estimated by the correlation analysis to be about 19 percent. It is shown that significant variability remains in Lyman alpha irradiance, with periods around 300, 27, and 13.5d, which is not explained by the solar activity indices. It is shown that the nonlinear effects cannot account for a significant part of the unexplained variation in Lyman alpha irradiance. Therefore, additional events (e.g., large-scale motions and/or a systematic difference in the area and intensity of the plages and network observed in the lines of Ca-K, He 1083, and Lyman alpha) may explain the discrepancies found between the observed and estimated irradiance values.

  7. Scale relativity and fractal space-time: theory and applications

    E-print Network

    Laurent Nottale

    2008-12-19

    In the first part of this contribution, we review the development of the theory of scale relativity and its geometric framework constructed in terms of a fractal and nondifferentiable continuous space-time. This theory leads (i) to a generalization of possible physically relevant fractal laws, written as partial differential equation acting in the space of scales, and (ii) to a new geometric foundation of quantum mechanics and gauge field theories and their possible generalisations. In the second part, we discuss some examples of application of the theory to various sciences, in particular in cases when the theoretical predictions have been validated by new or updated observational and experimental data. This includes predictions in physics and cosmology (value of the QCD coupling and of the cosmological constant), to astrophysics and gravitational structure formation (distances of extrasolar planets to their stars, of Kuiper belt objects, value of solar and solar-like star cycles), to sciences of life (log-periodic law for species punctuated evolution, human development and society evolution), to Earth sciences (log-periodic deceleration of the rate of California earthquakes and of Sichuan earthquake replicas, critical law for the arctic sea ice extent) and tentative applications to system biology.

  8. Ion time scale dispersion relations and fluctuations at comets

    NASA Astrophysics Data System (ADS)

    Gunell, Herbert; Nilsson, Hans; Eriksson, Anders; Wedlund, Cyril Simon; Stenberg Wieser, Gabriella; Kallio, Esa; Yamauchi, Masatoshi; Behar, Etienne; Maggiolo, Romain; Dhooghe, Frederik; De Keyser, Johan

    2015-04-01

    The Rosetta spacecraft has been accompanying comet 67P/Churyumov-Gerasimenko since 2014. As the comet approached the sun, the outgassing rate increased, and the thus created neutral atmosphere started to interact with the solar wind. The Rosetta Plasma Consortium (RPC) ion instruments have observed these interaction processes at this low activity comet. These observations include deflection of solar wind protons and alpha particles; singly charged helium ions being produced in charge exchange collisions between solar wind alpha particles and cometary neutrals; and water ions of cometary origin that have been accelerated by the solar wind electric field. These populations combine to form an ion distribution function. We use the RPC Ion Composition Analyser (RPC-ICA) to measure that distribution function, which we then analyse for fluctuations and dispersion relations on the ion time scale.

  9. Time-scale modelling of the invasive species Robinia pseudoacacia

    NASA Astrophysics Data System (ADS)

    Tomaž, Podobnikar; Andraž, Ä.?Arni; Imelda, Somodi

    2010-05-01

    Our contribution is part of the TransEcoNet project (Transnational Ecological Networks in Central Europe) that aims to investigate transboundary ecological networks across Central Europe. An objective of this project is to contribute towards awareness rising on the value and role of ecological networks. This poster presents the activities that are carried out in Pomurje region, Slovenia as our case study area. Pomurje region borders with Austria in the north, to Hungary in the east, and to Croatia in the south. We are investigating the spread of the invasive species Robinia pseudacacia and the underlying causes, and assess landscape scale ecological dynamics (e.g. Mura River floodplains) in ecological networks. The study comprises investigation and mapping of the R. pseudacacia spread with time-series analysis to understand its spatial dynamics. The preliminary studies show that the R. pseudacacia had the most expanded in the region since 1980s. Some of the surfaces were cut and converted back to fields. This reflects the socioeconomic situation in the region. The further study will include statistic, GIS (geographical information systems) and remote sensing techniques. We will apply various character data: satellite imagery, IR-orthophotos, digital elevation models, including LIDAR, contemporary and historical maps, and other spatial/non-spatial data sources. The outputs will include reconstruction of R. pseudacacia-dynamics in the recent decade, modelling the distribution of R. pseudacacia in relation to abiotic environmental factors and land use, and modelling (prediction) the expected distribution of R. pseudacacia in case of climate and land use change. Keywords: invasive species, Robinia pseudacacia, spatial analysis, time-scale analysis, remote sensing, land use change, climate change

  10. Water relations and leaf expansion: importance of time scale.

    PubMed

    Munns, R; Passioura, J B; Guo, J; Chazen, O; Cramer, G R

    2000-09-01

    The role of leaf water relations in controlling cell expansion in leaves of water-stressed maize and barley depends on time scale. Sudden changes in leaf water status, induced by sudden changes in humidity, light and soil salinity, greatly affect leaf elongation rate, but often only transiently. With sufficiently large changes in salinity, leaf elongation rates are persistently reduced. When plants are kept fully turgid throughout such sudden environmental changes, by placing their roots in a pressure chamber and raising the pressure so that the leaf xylem sap is maintained at atmospheric pressure, both the transient and persistent changes in leaf elongation rate disappear. All these responses show that water relations are responsible for the sudden changes in leaf elongation rate resulting from sudden changes in water stress and putative root signals play no part. However, at a time scale of days, pressurization fails to maintain high rates of leaf elongation of plants in either saline or drying soil, indicating that root signals are overriding water relations effects. In both saline and drying soil, pressurization does raise the growth rate during the light period, but a subsequent decrease during the dark results in no net effect on leaf growth over a 24 h period. When transpirational demand is very high, however, growth-promoting effects of pressurization during the light period outweigh any reductions in the dark, resulting in a net increase in growth of pressurized plants over 24 h. Thus leaf water status can limit leaf expansion rates during periods of high transpiration despite the control exercised by hormonal effects on a 24 h basis. PMID:11006301

  11. Use of a Walk Through Time to Facilitate Student Understandings of the Geological Time Scale

    NASA Astrophysics Data System (ADS)

    Shipman, H. L.

    2004-12-01

    Students often have difficulties in appreciating just how old the earth and the universe are. While they can simply memorize a number, they really do not understand just how big that number really is, in comparison with other, more familiar student referents like the length of a human lifetime or how long it takes to eat a pizza. (See, e.g., R.D. Trend 2001, J. Research in Science Teaching 38(2): 191-221) Students, and members of the general public, also display such well-known misconceptions as the "Flintstone chronology" of believing that human beings and dinosaurs walked the earth at the same time. (In the classic American cartoon "The Flintstones," human beings used dinosaurs as draft animals. As scientists we know this is fiction, but not all members of the public understand that.) In an interdisciplinary undergraduate college class that dealt with astronomy, cosmology, and biological evolution, I used a familiar activity to try to improve student understanding of the concept of time's vastness. Students walked through a pre-determined 600-step path which provided a spatial analogy to the geological time scale. They stopped at various points and engaged in some pre-determined discussions and debates. This activity is as old as the hills, but reports of its effectiveness or lack thereof are quite scarce. This paper demonstrates that this activity was effective for a general-audience, college student population in the U.S. The growth of student understandings of the geological time scale was significant as a result of this activity. Students did develop an understanding of time's vastness and were able to articulate this understanding in various ways. This growth was monitored through keeping track of several exam questions and through pre- and post- analysis of student writings. In the pre-writings, students often stated that they had "no idea" about how to illustrate the size of the geological time scale to someone else. While some post-time walk responses simply restated what was done in the walk through time, some students were able to develop their own ways of conceptualizing the vastness of the geological time scale. A variety of findings from student understandings will be presented. This work has been supported in part by the Distinguished Scholars Program of the National Science Foundation (DUE-0308557).

  12. Observing real time motion of nano-scale objects

    NASA Astrophysics Data System (ADS)

    van de Vondel, Joris; Timmermans, Matias; Samuely, Tomás; Raes, Bart; Serrier-Garcia, Lise; Moshchalkov, Victor

    2015-03-01

    The dynamics of nanoscale objects is a very interesting field of research with a strong technological impact. Still, the combination of a technique resolving (sub)nanometer particles within a time frame relevant to observe dynamics is a very challenging task. Due to the inherent atomic-scale resolution, scanning tunneling microscopy (STM) is an ideal candidate to achieve this goal. Nevertheless, in most physical systems the dynamic events of the objects under investigation cannot be resolved by conventional STM image acquisition and will only reveal an average trace of the moving object. This is why a strong drive exists to develop new functionalities of STM, which allow studying dynamic events at the nanoscale. We address this issue, for vortex matter in NbSe2, by driving the vortices using an ac magnetic field and probing the induced periodic tunnel current modulations. Our results reveal different dynamical modes of the driven vortex lattice. In addition, by extending a known functionality of STM, (i.e. the `Lazy Fisherman' technique) we can use single pixel information to obtain the overall dynamics of the vortex lattice with submillisecond time resolution and subnanometer spatial resolution. This work is supported by the FWO and the Methusalem funding of the Flemish government.

  13. Age and provenance of Triassic to Cenozoic sediments of West and Central Sarawak, Malaysia

    NASA Astrophysics Data System (ADS)

    Breitfeld, H. Tim; Galin, Thomson; Hall, Robert

    2015-04-01

    Sarawak is located on the northern edge of Sundaland in NW Borneo. West and Central Sarawak include parts of the Kuching and Sibu Zones. These contain remnants of several sedimentary basins with ages from Triassic to Cenozoic. New light mineral, heavy mineral and U-Pb detrital zircon ages show differences in provenance reflecting the tectonic evolution of the region. The oldest clastic sediments are Triassic (Sadong Formation and its deep marine equivalent Kuching Formation). They were sourced by a Triassic (Carnian to Norian) volcanic arc and reworked Paleoproterozoic detritus derived from Cathaysialand. The Upper Jurassic to Cretaceous Pedawan Formation is interpreted as forearc basin fill with distinctive zircon populations indicating subduction beneath present-day West Sarawak which initiated in the Late Jurassic. Subsequent subduction until the early Late Cretaceous formed the Schwaner Mountains magmatic arc. After collision of SW Borneo and other microcontinental fragments with Sundaland in the early Late Cretaceous, deep marine sedimentation (Pedawan Formation) ceased, and there was uplift forming the regional Pedawan-Kayan unconformity. Two episodes of extension followed and were responsible for basin development on land in West Sarawak from the latest Cretaceous onwards, probably in a pull-apart setting. The first episode is associated with sediments of the Kayan Group, deposited in the Latest Cretaceous (Maastrichtian) to Eocene, and the second episode with Upper Eocene sediments of the Ketungau Basin. Zircon ages indicate volcanic activity throughout the Early Cenozoic in NW Borneo, and inherited zircon ages indicate reworking of Triassic and Cretaceous rocks. A large deep marine basin, the Rajang Basin, was north of the Lupar Line Fault in Central Sarawak (Sibu Zone) from the Late Cretaceous to the Late Eocene. Zircons from sediments of the Rajang Basin indicate they have similar ages and provenance to contemporaneous terrestrial sediments of the Kayan Group and Ketungau Basin to the south, suggesting a narrow steep continental Sundaland margin at the position of the Lupar Line, and a large-scale sedimentary connection between the terrestrial and deep marine basins in the Late Cretaceous to Late Eocene. A recent reconstruction for the proto-South China Sea proposed an isolated so-called Semitau terrane colliding with SW Borneo and Sundaland in the Late Eocene. Our data show that the area of the Kuching and Sibu Zones were connected with SW Borneo and Sundaland from the Cretaceous onwards. The Cretaceous and Cenozoic sedimentary basins were sourced by alternations of Schwaner Mountains and Malay Tin Belt rocks. Our new age and provenance data cannot be explained by an isolated Semitau terrane and a Late Eocene collision.

  14. Geometric integrators for multiple time-scale simulation

    NASA Astrophysics Data System (ADS)

    Jia, Zhidong; Leimkuhler, Ben

    2006-05-01

    In this paper, we review and extend recent research on averaging integrators for multiple time-scale simulation such as are needed for physical N-body problems including molecular dynamics, materials modelling and celestial mechanics. A number of methods have been proposed for direct numerical integration of multiscale problems with special structure, such as the mollified impulse method (Garcia-Archilla, Sanz-Serna and Skeel 1999 SIAM J. Sci. Comput. 20 930-63) and the reversible averaging method (Leimkuhler and Reich 2001 J. Comput. Phys. 171 95-114). Features of problems of interest, such as thermostatted coarse-grained molecular dynamics, require extension of the standard framework. At the same time, in some applications the computation of averages plays a crucial role, but the available methods have deficiencies in this regard. We demonstrate that a new approach based on the introduction of shadow variables, which mirror physical variables, has promised for broadening the usefulness of multiscale methods and enhancing accuracy of or simplifying computation of averages. The shadow variables must be computed from an auxiliary equation. While a geometric integrator in the extended space is possible, in practice we observe enhanced long-term energy behaviour only through use of a variant of the method which controls drift of the shadow variables using dissipation and sacrifices the formal geometric properties such as time-reversibility and volume preservation in the enlarged phase space, stabilizing the corresponding properties in the physical variables. The method is applied to a gravitational three-body problem as well as a partially thermostatted model problem for a dilute gas of diatomic molecules.

  15. Studying the Dynamics of Problem Behavior Across Multiple Time Scales: Prospects and Challenges

    Microsoft Academic Search

    George W. Howe

    2004-01-01

    As a commentary on the Special Issue, this paper discusses recent advances in the study of change across several time scales. It points out the importance of specifying time scales and putative patterns of change when characterizing problem behavior over developmental time scales. Methods for studying risk and protective mechanisms through observation of social interaction are also discussed as a

  16. The carbon-isotope shift at the Permian\\/Triassic boundary in the southern Alps is gradual

    Microsoft Academic Search

    Mordeckai Magaritz; Richard Bart; Aymon Baud; William T. Holser

    1988-01-01

    Carbon isotope ratios in marine carbonate rocks have been shown to shift at some of the time boundaries associated with extinction events; for example, Cretaceous\\/Tertiary1 and Ordovician\\/ Silurian2. The Permian\\/Triassic boundary, the greatest extinction event of the Phanerozoic3, is also marked by a large delta13C depletion4,5. New carbon isotope results from sections in the southern Alps show that this depletion

  17. Plume-lithosphere interaction in generation of the Emeishan flood basalts at the Permian-Triassic boundary

    Microsoft Academic Search

    Sun-Lin Chung; Bor-Ming Jahn

    1995-01-01

    The Emeishan flood volcanism that erupted at Permian-Triassic boundary time produced a large igneous province of at least 2.5 X 105 km2 in the western margin of the Yangtze craton, southwestern China. The volcanic successions, suggested to have resulted from a starting mantle plume, comprise thick piles of basaltic flows and subordinate picrites and pyroclastics. The picrites, which have high

  18. Triassic 40 Ar ages from the Sakaigawa unit, Kii Peninsula,

    E-print Network

    Paris-Sud XI, Université de

    , but on the Pacific side of the proto-Japan superterrane. Proto-Japan was a Permian magmatic arc, presently dispersed that this system continued via the Cathaysia block (China) to Indochina. The Late Permian to Middle Triassic Indosinian event might stem from docking of Pacific-derived terranes with Southeast Asia's continental margin

  19. A new chronology for the end-Triassic mass extinction

    Microsoft Academic Search

    M. H. L. Deenen; M. Ruhl; N. R. Bonis; W. Krijgsman; W. M. Kuerschner; M. Reitsma; M. J. van Bergen

    2010-01-01

    The transition from the Triassic to Jurassic Period, initiating the ‘Age of the dinosaurs’, approximately 200Ma, is marked by a profound mass extinction with more than 50% genus loss in both marine and continental realms. This event closely coincides with a period of extensive volcanism in the Central Atlantic Magmatic Province (CAMP) associated with the initial break-up of Pangaea but

  20. Permo-Triassic Events in the Eastern Tethys

    Microsoft Academic Search

    Walter C. Sweet; Yang Zunyi; J. M. Dickins; Yin Hongfu

    2003-01-01

    Permian and Triassic rocks in the eastern Tethyan region form continuous marine sequences that record the waning phases of the Paleozoic and the early stages of the Mesozoic eras. This book describes and interprets these rocks, summarizing the distribution of major fossil groups in a way that will allow detailed comparison with strata of comparable age in the western Tethys

  1. Do the Cotham Member stromatolites of the Late Triassic, SW UK represent extinction "disaster forms"?

    NASA Astrophysics Data System (ADS)

    Ibarra, Y.; Corsetti, F. A.; Greene, S.; Bottjer, D. J.

    2011-12-01

    A widespread and well-preserved horizon (~20cm thick) of alternating stromatolite-dendrolite facies occurs at the top of the Cotham Member of the Lilstock Formation in the Upper Triassic (latest Rhaetian) of the SW UK. The close stratigraphic position to the Triassic-Jurassic (T-J) mass extinction interval raises questions about the potential relationship to the mass extinction. Were the Cotham Member stromatolites a result of a decline in taxonomic richness (including decline of bioturbators and grazers) across the Late Triassic extinction episode? Or, were they deposited in a hypersaline lagoon, an environment known to develop microbialites during non-extinction times, and therefore decoupled from the extinction event? Light microscopic observations of thin sections reveal a sparse assemblage of shelly epifauna including molluscs and echinoderm fragments. Carbon and oxygen isotope values of micro-drilled portions of the stromatolites exhibit ?13C values of -0.1% to -1.7% and ?18O values of -0.8% to -2.3%. We also observe 2 thin layers (each about 1mm thick) of gypsum pseudomorphs a few centimeters below the first occurrence of stromatolites. On the one hand, the isotopic evidence and the presence of echinoderm fragments (echinoderms/crinoids generally require open marine conditions) would argue against a restricted lagoonal origin for the stromatolites and dendrolites. On the other hand, the presence of evaporite minerals within cm of the stromatolitic units would argue for at least periodic restriction of the depositional environment. Consequently, more work is needed to unequivocally resolve the depositional environment of the Cotham Member stromatolites and their relevance to the T-J mass extinction.

  2. Late Triassic sinistral shear in the East Gobi Fault Zone, Mongolia

    NASA Astrophysics Data System (ADS)

    Webb, Laura E.; Johnson, Cari L.; Minjin, Chuluun

    2010-12-01

    Tectonic studies of the East Gobi Fault Zone in southeastern Mongolia reveal multiple, distinct intracontinental deformation events postdating late Paleozoic arc accretion and continental amalgamation. Metamorphic tectonites of the Tsagan Subarga and Tavan Har blocks, previously mapped as Precambrian basement, comprise a sinistral shear zone dominated by steeply-dipping, northeast-striking foliations. Field observations and petrographic analyses indicate that the protoliths of the metamorphic tectonites are Paleozoic arc volcanic and sedimentary sequences. 40Ar/ 39Ar step-heating analyses of minerals from pre-, syn-, and late- to post-kinematic lithologies bracket the timing of ductile sinistral shear as Late Triassic. The main phase of distributed deformation associated with cooling through amphibolite-upper greenschist-facies conditions occurred ca. 225 Ma and shear zone activity waned ca. 210 Ma. Cooling rates inferred from the 40Ar/ 39Ar data are on the order of 40-20 °C Myr - 1 ; apparent differences for the two basement blocks may reflect subsequent differential uplift during Late Jurassic-Cretaceous rifting. Relatively rapid Late Triassic cooling suggests a transtensional component to the deformation and is coincident with core complex formation in northern China. Late Triassic intraplate deformation in southeastern Mongolia is likely the result of far field forces associated with collision between Mongolian arcs and the Siberian craton (i.e. closure of the Mongol-Okhotsk ocean) and/or collisions associated with closure of the Paleotethys. The ductile shear zone has been documented over 250 km along strike and has been modified by subsequent brittle deformation events in the Mesozoic and Cenozoic.

  3. Permian Triassic palynofloral transition in Chintalapudi area, Godavari Graben, Andhra Pradesh, India

    NASA Astrophysics Data System (ADS)

    Jha, Neerja; Chary, M. Basava; Aggarwal, Neha

    2012-10-01

    The entire 606 m-thick sedimentary sequence in borecore MCP-7 from Chintalapudi area, Chintalapudi sub-basin has been lithologically designated as Kamthi Formation. However, the palynological investigation revealed five distinct palynoassemblages, which essentially fall under two groups, one group (Palynoassemblage-I, II and III) having dominance of striate disaccates along with presence of some stratigraphically significant taxa, belongs to Late Permian (Raniganj) palynoflora, while the other group (Palynoassemblages IV and V) shows sharp decline in percentage of characteristic taxa of first group, i.e., striate disaccates, and consequent rise or dominance of taeniate and cingulate cavate spores, belongs to Early Triassic (Panchet) palynoflora. Palynoassemblage-I, II and III (Group I) are characterized by dominance of striate disaccates chiefly, Striatopodocarpites spp. and Faunipollenites spp. along with presence of rare but stratigraphically significant taxa, viz., Gondisporites raniganjensis, Falcisporites nuthaliensis, Klausipollenites schaubergeri, Chordasporites sp., Striomonosaccites, ovatus, Crescentipollenites multistriatus, Verticipollenites debiles, Strotersporites crassiletus, Guttulapollenites hannonicus, G. gondwanensis, Hamiapollenites insolitus, Corisaccites alutus, Lunatisporites ovatus, Weylandites spp. and Vitreisporites pallidus. Palynoassemblage-I is distinguished by significant presence of Densipollenites spp. while Palynoassemblage-II shows significant presence of Crescentipollenites spp. and Palynoassemblage-III differs from the above two assemblages in having significant presence of Guttulapollenites hannonicus. Palynoassemblage-IV (Group II) is characterized by high percentage of taeniate disaccates chiefly Lunatisporites spp., while Palynoassemblage-V (Group II) is characterized by cingulate-cavate trilete spores chiefly, Lundbladispora spp. and Densoisporites spp. Striate disaccates show a sharp decline in these two assemblages. In Chintalapudi area Late Permian and Early Triassic palynoflora has been recorded for the first time indicating existence of Raniganj and Panchet sediments as well. The study further supports the earlier studies of Jha and Srivastava (1996) that Kamthi Formation represents Early Triassic (=Panchet Formation) overlying Raniganj equivalent sediments with a gradational contact.

  4. The Late Triassic and Late Jurassic stress fields and tectonic transmission of North China craton

    NASA Astrophysics Data System (ADS)

    Hou, Guiting; Wang, Yanxin; Hari, K. R.

    2010-09-01

    The transmission of the tectonic regime from the Paleo-Asian Ocean to the Pacific Ocean during Mesozoic era was reconstructed using the modeling of Late Triassic (T 3) and Late Jurassic (J 3) stress fields employing two dimensional linear finite element models (2-D FEM). The model at T 3 proposes that Qinling-Dabie-Sulu orogens coevally collided and the model J 3 proposes that Subei block continued to collide with the North China block along the Sulu orogen while the collision of the Qinling-Dabie orogen was terminated. The stress fields at T 3 and J 3 during the two episodes were calculated based on mechanical conditions under different deviatoric stresses acting along the boundaries of the North China craton by elastic finite modeling. The transmission between two episodes of stress fields resulted from Qinling-Dabie-Sulu collision between North China and South China in the Late Triassic period, and from continued collision between the Subei block and North China by the NW-trending movement of Izanagi plate during Late Jurassic. The results from modeling of the Mesozoic stress fields of the North China suggest that late Jurassic was the key transmission period of the tectonic regime of the North China block when large scale thrusting triggered the subsequent destruction of the North China craton.

  5. Paleoclimate cycles and tectonic controls on fluvial, lacustrine, and eolian strata in upper Triassic Chinle Formation, San Juan basin

    SciTech Connect

    Dubiel, R.F. (Geological Survey, Denver, CO (USA))

    1989-09-01

    Sedimentologic study of the Upper Triassic Chinle Formation in the San Juan basin (SJB) indicates that Late Triassic paleoclimate and tectonic movements influenced the distribution of continental lithofacies. The Shinarump, Monitor Butte, and Petrified Forest Members in the lower part of the Chinle consist of complexly interfingered fluvial, floodplain, marsh, and lacustrine rocks; the Owl Rock and Rock Point Members in the upper part consists of lacustrine-basin and eolian sandsheet strata. Facies analysis, vertebrate and invertebrate paleontology, and paleoclimate models demonstrate that the Late Triassic was dominated by tropical monsoonal circulation, which provided abundant precipitation interspersed with seasonally dry periods. Owl Rock lacustrine strata comprise laminated limestones that reflect seasonal monsoonal precipitation and larger scale, interbedded carbonates and fine-grained clastics that represent longer term, alternating wet and dry climatic cycles. Overlying Rock Point eolian sand-sheet and dune deposits indicate persistent alternating but drier climatic cyclicity. Within the Chinle, upward succession of lacustrine, alternating lacustrine/eolian sand-sheet, and eolian sand-sheet/dune deposits reflects an overall decrease in precipitation due to the northward migration of Pangaea out of low latitudes dominated by monsoonal circulation.

  6. Oil and gas potential of the Triassic in west Siberia

    SciTech Connect

    Bochkarev, V.S.; Kulakhmetov, N.KH.; Nesterov, I.I. (ZapSibNIGNI, Tyumen (Russian Federation))

    1993-09-01

    Permian-Triassic rocks are widely spread within the West Siberian basin, and they include volcanics, volcanoclastics, and clastics. Their thickness varies from tens of meters of 3000 m. Recently, three commercial oil pools have been discovered in Triassic effusive-sedimentary rocks. These discoveries, together with other geological and geochemical data, identify the Triassic complex as a major play. Oil-bearing intervals have been found in three different types of sequences; a fourth also may be prospective. The first type is represented by lacustrine-terrigenous sediments, which comprise oil-saturated sandstones interbedded with basalts (the Turin series). Oil influxes were obtained in the Yakhlinskaya and Triyurtin-skaya structures in the Shaim region. The second type is distinguished from the first by the presence of coal-bearing intervals in the upper part. Oil was produced in the Yerofeyev area of the Chelyabinsk garben. The third type differs from the other two by the presence of potassic rhyolites and dacites. Their age is not precisely dated, and supposedly they are of Permian age. The largest oil influxes have been obtained from fractured and eroded rocks of this type in the Rogozhnikovskaya and other places in the Krasnoleninsk region. Rhyodacites often underlie Turin basalts, but locally they occur in the upper part of the series. Triassic and Permian-Trissic rocks of the three types are overlain by Jurassic and Cretaceous rocks with a large break. The fourth type of section is completely terrigenous (Tampei series). It is developed in the northern part of west Siberia. Here Triassic sediments are overlain by the Jurassic complex without a break. According to well-log data, productive horizons occur at Urengoy and Beregovaya (in the Urengoy region).

  7. Science at the Time-scale of the Electron

    NASA Astrophysics Data System (ADS)

    Murnane, Margaret

    2010-03-01

    Replace this text with your abstract Ever since the invention of the laser 50 years ago and its application in nonlinear optics, scientists have been striving to extend coherent laser beams into the x-ray region of the spectrum. Very recently however, the prospects for tabletop coherent sources, with attosecond pulse durations, at very short wavelengths even in the hard x-ray region of the spectrum at wavelengths < 1nm, have brightened considerably. These advances are possible by taking nonlinear optics techniques to an extreme, and are the direct result of a new ability to manipulate electrons on the fastest, attosecond, time-scales of our natural world. My talk will discuss new experimental data that demonstrates high harmonic generation of laser-like, fully coherent, 10 attosecond duration, soft x-ray beams at photon energies around 0.5keV. Several applications will also be discussed, including making a movie of how electron orbitals in a molecule change shape as a molecule breaks apart, following how fast a magnetic material can flip orientation, understanding how fast heat flows in a nanocircuit, or building a microscope without lenses. [4pt] [1] T. Popmintchev et al., ``Phase matched upconversion of coherent ultrafast laser light into the soft and hard x-ray regions of the spectrum'', PNAS 106, 10516 (2009). [0pt] [2] C. LaOVorakiat et al., ``Ultrafast Soft X-Ray Magneto-Optics at the M-edge Using a Tabletop High-Harmonic Source'', Physical Review Letters 103, 257402 (2009). [0pt] [3] M. Siemens et al. ``Measurement of quasi-ballistic heat transport across nanoscale interfaces using ultrafast coherent soft x-ray beams'', Nature Materials 9, 26 (2010). [0pt] [4] K. Raines et al., ``Three-dimensional structure determination from a single view,'' Nature 463, 214 (2010). [0pt] [5] W. Li et al., ``Time-resolved Probing of Dynamics in Polyatomic Molecules using High Harmonic Generation'', Science 322, 1207 (2008).

  8. Detonation initiation on the microsecond time scale: DDTs

    SciTech Connect

    Kassoy, Dr. David R [University of Colorado; Kuehn, Jeffery A [ORNL; Nabity, Mr. Matthew W. [University of Colorado; Clarke, Dr. John F. [Cranfield University

    2008-01-01

    Spatially resolved, thermal power deposition of limited duration into a finite volume of reactive gas is the initiator for a deflagration-to-detonation transition (DDT) on the microsecond time scale. The reactive Euler equations with one-step Arrhenius kinetics are used to derive novel formulas for velocity and temperature variation that describe the physical phenomena characteristic of DDTs. A transformation of the variables is shown to yield a canonical equation system, independent of the activation energy. Numerical solutions of the reactive Euler equations are used to describe the detailed sequence of reactive gasdynamic processes leading to an overdriven planar detonation far from the power deposition location. Results are presented for deposition into a region isolated from the planar boundary of the reactive gas as well as for that adjacent to the boundary. The role of compressions and shocks reflected from the boundary into the partially reacted hot gas is described. The quantitative dependences of DDT evolution on the magnitude of thermal power deposition and activation energy are identified.

  9. Detonation initiation on the microsecond time scale: DDTs

    SciTech Connect

    Kuehn, Jeffery A [ORNL; Kassoy, Dr. David R [University of Colorado; Nabity, Mr. Matthew W. [University of Colorado; Clarke, Dr. John F. [Cranfield University

    2006-01-01

    Spatially resolved, thermal power deposition of limited duration into a finite volume of reactive gas is the initiator for a deflagration-to-detonation transition (DDT) on the microsecond time scale. The reactive Euler equations with one-step Arrhenius kinetics are used to derive novel formulas for velocity and temperature variation that describe the physical phenomena characteristic of DDTs. A nonlinear transformation of the variables is shown to yield a canonical equation system, independent of the activation energy. Numerical solutions of the reactive Euler equations are used to describe the detailed sequence of reactive gas dynamic processes leading to an overdriven planar detonation far from the power deposition location. Results are presented for deposition into a region isolated from the planar boundary of the reactive gas as well as for that adjacent to the boundary. The role of compressions and shocks reflected from the boundary into the partially reacted hot gas is described. The quantitative dependences of DDT evolution on the magnitude of thermal power deposition and activation energy are identified.

  10. The Triassic dicynodont Kombuisia (Synapsida, Anomodontia) from Antarctica, a refuge from the terrestrial Permian-Triassic mass extinction

    NASA Astrophysics Data System (ADS)

    Fröbisch, Jörg; Angielczyk, Kenneth D.; Sidor, Christian A.

    2010-02-01

    Fossils from the central Transantarctic Mountains in Antarctica are referred to a new species of the Triassic genus Kombuisia, one of four dicynodont lineages known to survive the end-Permian mass extinction. The specimens show a unique combination of characters only present in this genus, but the new species can be distinguished from the type species of the genus, Kombuisia frerensis, by the presence of a reduced but slit-like pineal foramen and the lack of contact between the postorbitals. Although incomplete, the Antarctic specimens are significant because Kombuisia was previously known only from the South African Karoo Basin and the new specimens extend the taxon’s biogeographic range to a wider portion of southern Pangaea. In addition, the new finds extend the known stratigraphic range of Kombuisia from the Middle Triassic subzone B of the Cynognathus Assemblage Zone into rocks that are equivalent in age to the Lower Triassic Lystrosaurus Assemblage Zone, shortening the proposed ghost lineage of this taxon. Most importantly, the occurrence of Kombuisia and Lystrosaurus mccaigi in the Lower Triassic of Antarctica suggests that this area served as a refuge from some of the effects of the end-Permian extinction. The composition of the lower Fremouw Formation fauna implies a community structure similar to that of the ecologically anomalous Lystrosaurus Assemblage Zone of South Africa, providing additional evidence for widespread ecological disturbance in the extinction’s aftermath.

  11. Some aspects of the Permian–Triassic boundary (PTB) and of the possible causes for the biotic crisis around this boundary

    Microsoft Academic Search

    H. W Kozur

    1998-01-01

    The first appearance datum (FAD) of Hindeodusparvus is an excellent datum very close to the base of the Otoceraswoodwardi Zone (priority base of the Triassic). For the first time, it allows an exact correlation of the PTB in all marine facies and faunal realms. The following features of the extinction and recovery patterns near the PTB are most important for

  12. Reconstructing paleoenvironment in the west-tethyan continental domain at the Late Permian and Early Triassic from sedimentological and palaeobotanical data

    Microsoft Academic Search

    Antoine Bercovici; Sylvie Bourquin; Jean Broutin; José B. Diez

    2010-01-01

    The final buildup of Pangea at the end of the Palaeozoic led to the formation of massive landmass unrivaled in later times. On a climatic perspective, the end of the Carboniferous ice age opened into a period of progressive warming, creating vast arid regions on land. The lower Triassic is the culmination of this trend, and represents a period where

  13. The lower Triassic microbiolites in Chaohu region, East China and their contribution to the early Triassic recovery

    NASA Astrophysics Data System (ADS)

    Jia, Zhihai; Zhang, Liwei; Hong, Tianqiu

    2010-05-01

    The lower Triassic is well preserved in Chaohu Region, Anhui Province, East China. It can be divided into Yinkeng Formation (80 meters thick, was formed during the Indian and early Smitian), Helongshan Formation (21 meters thick, was formed during the end Smithian) and Nanlinghu Formation (more than 157 meters thick, was formed during the Spathian) from bottom to top. It is mainly composed of carbonatites such as micrite limestones and nodular limestones, as well as shales and calcareous marls. The lower Triassic in this area has been well researched for more than a decade, and many fossils such as ammonites, bivalves, fishes, ichthyosaurus, conodonts, and ichnofossils have been found, but the microbiolites have been neglected. Microbiolites were mainly outcropped in the Helongshan Formaiton and the lower Nanlinghu Formation. In the lower Helongshan Formaiton, tens microbial mat layers and thin bedded calcareous marl layers formed cyclothems which have been named as nodular limstones. The thin-section observation of the microbial mats indicate that many films and thin-shell bivalve fragments deposited almost horizontally. In the upper Helongshan Formaiton, six microstromatolite bioherm layers were outcropped in the thin bedded calcareous marl layers. The diameter of the stromatolite column is about 2 millimeters, the bioherms are lenticular and no more than 3 centimeters thick in the central, their diameters change from 5 centimeters to 30 centimeters, calcareous marls were deposited around the bioherms, and many ammonoids, bivalves and burrows were found in such layers. The microfacies differentiation of the stromatolites such as the basement, reef core and the capping beds can be recognised clearly in thin sections. Several microstromatolite layers were outcropped in the micritic limestones with a stable thickness of 15 millimeters in the lower Nanlinghu Formation and the stromatolite column look like the ones in the Helongshan Formation. Few microbiolites have been found in the middle and upper Nanlinghu Formation. The macro fossil association of the lower Triassic in Chaohu region is quite different in different Formations. Ammonoids and bivalves can be found in the whole lower Triassic strata, and they are especially dominant in the Yinkeng Formation and lower Helongshan Formaiton, worms and borrowing animals can be found in the middle Helongshan Formation, fishes can be found in the uppermost Helongshan Formation and the lower Nanlinghu Formation, and the oldest ichthyosaurus in the world can be found in the upper Nanlinghu Formation. According to the changing characters of the fossil association in this area, it is indicated that the high-level ecosystem had been formed in this area in the late early Triassic, and the appearance of the microbiolites in the Helongshan Formation might be the milestone for the early Triassic recovery. Though the global recovery process after the Permian-Triassic mass extinction might be postponed to the end of the early Triassic, regional recovery process in Chaohu region might start at the end Smithian and actualized at the middle Spathian. The microbioilites might be the original impetus for the early Triassic recovery. Key words: microbiolites, early Triassic, regional recovery, Chaohu region Acknowledgments This work is supported by the grants from National Natural Science Fundation of China (No. 40902096 and No.J0830522) and the IGCP 572 program. * Corresponding author: zhihai.jia@gmail.com

  14. Asymmetry of Information Flow Between Volatilities Across Time Scales

    E-print Network

    Whitcher, Brandon

    markets, stock markets, multiresolution analysis, scaling. JEL No: G0, G1, C1 Department of Economics clustering (conditional heteroscedasticity) and long memory (slowly decaying autocorrelation). Both prop

  15. Palaeo-equatorial temperatures and carbon-cycle evolution at the Triassic- Jurassic boundary: A stable isotope perspective from shallow-water carbonates from the UAE

    NASA Astrophysics Data System (ADS)

    Honig, M. R.; John, C. M.

    2013-12-01

    The Triassic-Jurassic boundary was marked by global changes including carbon-cycle perturbations and the opening of the Atlantic Ocean. These changes were accompanied by one of the major extinction events of the Phanerozoic. The carbon-cycle perturbations have been recorded in carbon isotope curves from bulk carbonates, organic carbon and fossil wood in several Tethyan locations and have been used for chemostratigraphic purposes. Here we present data from shallow-marine carbonates deposited on a homoclinal Middle Eastern carbonate ramp (United Arab Emirates). Our site was located at the equator throughout the Late Triassic and the Early Jurassic, and this study provides the first constraints of environmental changes at the low-latitudes for the Triassic-Jurassic boundary. Shallow-marine carbonate depositional systems are extremely sensitive to palaeoenvironmental changes and their usefulness for chemostratigraphy is being debated. However, the palaeogeographic location of the studied carbonate ramp gives us a unique insight into a tropical carbonate factory at a time of severe global change. Stable isotope measurements (carbon and oxygen) are being carried out on micrite, ooids and shell material along the Triassic-Jurassic boundary. The stable isotope results on micrite show a prominent negative shift in carbon isotope values of approximately 2 ‰ just below the inferred position of the Triassic-Jurassic boundary. A similar isotopic trend is also observed across the Tethys but with a range of amplitudes (from ~2 ‰ to ~4 ‰). These results seem to indicate that the neritic carbonates from our studied section can be used for chemostratigraphic purposes, and the amplitudes of the carbon isotope shifts provide critical constraints on the magnitude of carbon-cycle perturbations at low latitudes across the Triassic-Jurassic boundary. Seawater temperatures across the Triassic-Jurassic boundary will be constrained using the clumped isotope palaeo-thermometer applied to blocky calcite, bulk carbonate, oyster shells and echinoids. Assuming a pristine depositional signal can be extracted from one of the components, clumped isotopes will either shed light on the palaeoenvironmental conditions and the isotopic composition of a tropical ocean during the Late Triassic / Early Jurassic, or on the diagenetic history of the platform. We gratefully acknowledge funding from Qatar Petroleum, Shell, and Qatar Science & Technology Park.

  16. Collisional Time Scales in the Kuiper Disk and Their Implications

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan

    1995-01-01

    We explore the rate of collisions among bodies in the present-day Kuiper Disk as a function of the total mass and population size structure of the disk. We find that collisional evolution is an important evolutionary process in the disk as a whole, and indeed, that it is likely the dominant evolutionary process beyond approx. 42 AU, where dynamical instability time scales exceed the age of the solar system. Two key findings we report from this modeling work are: that unless the disk's population structure is sharply truncated for radii smaller than approx. 1-2 km, collisions between comets and smaller debris are occurring so frequently in the disk, and with high enough velocities, that the small body (i.e., KM-class object) population in the disk has probably developed into a collisional cascade, thereby implying that the Kuiper Disk comets may not all be primordial, and that the rate of collisions of smaller bodies with larger 100 less R less 400 km objects (like 1992QB(sub 1) and its cohorts) is so low that there appears to be a dilemma in explaining how QB(sub 1)s could have grown by binary accretion in the disk as we know it. Given these findings, it appears that either the present-day paradigm for the formation of Kuiper Disk is failed in some fundamental respect, or that the present-day disk is no longer representative of the ancient structure from which it evolved. This in turn suggests the intriguing possibility that the present-day Kuiper Disk evolved through a more erosional stage reminiscent of the disks around the stars Beta Pictorus, alpha PsA, and alpha Lyr.

  17. Particle tracking for fractional diffusion with two time scales

    Microsoft Academic Search

    Mark M. Meerschaert; Yong Zhang; Boris Baeumer

    2010-01-01

    Previous work (51) showed how to solve time-fractional diffusion equa- tions by particle tracking. This paper extends the method to the case where the order of the fractional time derivative is greater than one. A subordination approach treats the fractional time derivative as a random time change of the correspond- ing Cauchy problem, with a first derivative in time. One

  18. Real time density functional simulations of quantum scale conductance

    E-print Network

    Evans, Jeremy Scott

    2009-01-01

    We study electronic conductance through single molecules by subjecting a molecular junction to a time dependent potential and propagating the electronic state in real time using time-dependent density functional theory ...

  19. The biology of time across different scales Dean V Buonomano

    E-print Network

    Buonomano, Dean

    a traffic light will change,or control the circadian fluctuations in sleep-wake cycles. The mechanisms oscillations, such as our sleep-wake cycle. In-between these extremes temporal processing occurs on the scale

  20. Late Permian to Late Triassic basin evolution of North Vietnam: geodynamic implications for the South China and Indochina blocks

    NASA Astrophysics Data System (ADS)

    Rossignol, Camille; Bourquin, Sylvie; Hallot, Erwan; Poujol, Marc; Roger, Françoise

    2015-04-01

    The core of South East Asia is composed of a mosaic of continental blocks, among which the Indochina and the South China blocks (present day northern Vietnam), amalgamated during the Permian and/or the Triassic. Late Permian to Late Triassic geodynamic evolution of these two blocks remains controversial. The main discussion points concern the existence and the closure of an oceanic domain separating the Indochina and the South China blocks during this period. Especially, the polarity and the timing of the subduction zone that led to the collision between the blocks as well as the present location of the suture delimiting them are a matter of debate. Despite the valuable information they can provide, the sedimentary basins from northern Vietnam have been neglected in the previous studies dealing with the geodynamic evolution of South East Asia. To determine the geodynamic evolution of the area, the basins of Sam Nua and Song Da, presently located in North Vietnam, have been investigated using a combined approach involving sedimentology, geochronology (U-Pb/zircon) and geochemistry (whole-rock major and trace elements composition of both volcanic and volcaniclastic rocks). The palaeoenvironment evolution, the main unconformities, their age and the tectonic affinities of the interbedded volcanic and volcaniclastics series have been characterized for these two basins. Our results demonstrate (i) that the Song Da Basin exhibits a palaeogeographic affinity with the South China block, (ii) the occurrence of extensive calk-alkaline volcanism and associated volcaniclastic deposits in the Sam Nua Basin, related to the existence of an active magmatic arc during the Early and the lower Middle Triassic, (iii) a South dipping (present day coordinate) oceanic lithosphere beneath the Indochina block, deduced from the location of the magmatic arc south of the potential suture zones, (iv) that an angular unconformity postdates the lower Middle Triassic volcaniclastic deposits in the Sam Nua basin. This unconformity, crosscutting the subduction related deposits, is interpreted as the result of the collision between the Indochina and the South China blocks.

  1. Geochronology, geochemistry and Hf isotope of Late Triassic magmatic rocks of Qingchengzi district in Liaodong peninsula, Northeast China

    NASA Astrophysics Data System (ADS)

    Duan, Xiaoxia; Zeng, Qingdong; Yang, Jinhui; Liu, Jianming; Wang, Yongbin; Zhou, Lingli

    2014-09-01

    The initiation timing and mechanism of lithospheric thinning of the North China Craton (NCC) was still controversial. Late Triassic igneous rocks especially mantle derived mafic rocks would provide constrains on Early Mesozoic lithospheric mantle geodynamics and initiation of lithospheric thinning. This paper reports Late Triassic magmatic rocks, including lamprophyre, diorite dykes and biotite monzogranite cropped out in Qingchengzi district of Liaodong peninsula, northeastern NCC. LA-ICPMS zircon U-Pb dating yield ages of 210-227 Ma and 224 Ma for lamprophyres and biotite monzogranite respectively. Lamprophyre is ultrapotassic, strongly enriched in REE and LILEs, depleted in HFSEs, and negative Hf isotopes, which are discriminating signatures of crustal source, but distinguishingly high compatible element contents indicate the primary magma originated from mantle source-a fertile one. Lamprophyre derived from partial melting of an enriched lithospheric mantle, which was modified by slab-derived hydrous fluids/melts associated with deep subduction between the Yangtze Craton and the NCC. The diorite displays distinct features with relatively enriched Nb, Ta, HREE and depleted Th, U, which suggest it derived from a relatively depleted source. The depletion was caused by break-off of the Yangtze slab during deep subduction introducing asthenospheric mantle into the source. The biotite monzogranite shows adakitic affinity, and originated from partial melting of the thickened lower crust with addition of small proportion of mantle material. The recognition of Late Triassic magmatism implies extensional tectonic settings in Liaodong peninsula and suggests initiation of lithospheric thinning of North China Craton in eastern segment might begin early in Late Triassic.

  2. Terrestrial events across the Permian Triassic boundary along the Yunnan Guizhou border, SW China

    NASA Astrophysics Data System (ADS)

    Jianxin, Yu; Yuanqiao, Peng; Suxin, Zhang; Fengqing, Yang; Quanming, Zhao; Qisheng, Huang

    2007-01-01

    The border area between western Guizhou and eastern Yunnan Provinces in SW China is an ideal place to undertake research considering the terrestrial-ecological system evolution across the Permian-Triassic boundary (PTB). The study of plant and palynomorph fossils, clay minerals, inorganic geochemistry and sedimentary facies in this area enable us to interpret the events occurring at that time. The extinction pattern of the flora interpreted from megafloral and palynomorph data is demonstrated by a sudden decline of species numbers at the PTB after a long-term of gradual changes, followed by a delayed extinction in the basal Triassic. The two boundary claybeds (Beds 66 and 68 in the Chahe Section, beds 47 and 49 in the Zhejue Section) are considered to be volcanogenic. The inorganic geochemical anomalies occurred between Beds 63 and 69, Chahe Section and Beds 45 and 50, Zhejue Section. Sedimentary facies changed from channels of braided rivers, into flood plains of braided rivers, then to shallow lakes, reflecting a gradual transgression by lakes across the area. Our conclusions are that the mass extinction across the PTB in western Guizhou and eastern Yunnan was probably caused by the Siberian basaltic eruption episode and the siliceous volcanism in South China. These lithospheric events represented by volcanisms heralded a series of climatic and environmental events, giving rise to a catastrophe for the biosphere.

  3. The Triassic taphoflora of the Paraná Basin, southern Brazil: a biostratigraphical approach

    NASA Astrophysics Data System (ADS)

    Guerra-Sommer, M.; Cazzulo-Klepzig, M.; Iannuzzi, R.

    1999-07-01

    A Triassic taphoflora identified in the Central Region of the State of Rio Grande do Sul, southern Brazil, represents an important biostratigraphical stage in the palæofloristic succession of the Paraná Basin. A megafloristic association composed of compressed leaves, fronds and seeds of a ' Dicroidium Flora' shows a predominance of the Dicroidium genus, with several species and other important taxa like Neocalamites sp., Cladophlebis sp., Tetraptilon aff. heteromerum, Ginkgoites antarctica, Sphenobaiera sp., Podozamites sp., Nilssonia sp., Pteruchus sp. and Carpolithus sp. Taking into account the stratigraphical distribution of different species of the Dicroidium genus, a biostratigraphical framework was established. Considering that the recognition of this ' Dicroidium Flora' was based on limited outcrops belonging to one lithostratiphical level (Santa Maria Formation — Passo das Tropas Facies), it was impossible to established a formal biostratigraphical zonation. Instead, at the present time, an informal floristic interval, named the ' Dicroidium odontopteroides Flora', is proposed (Late Anisian to Late Ladinian, Middle Triassic). An ' Araucarioxylon Flora' composed of secondary woods of the Araucarioxylon type and stems of Rhexoxylon brasiliensis was also identified several km apart. The compressed fossils of the ' Dicroidium Flora' and the petrified stems of the ' Araucarioxylon Flora' could represent different but contemporaneous communities corresponding to fluvial-lacustrine environments.

  4. Restudy of conodont biostratigraphy of the Permian-Triassic boundary section in Zhongzhai, southwestern Guizhou Province, South China

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Zhang, Ke-Xin; Shi, G. R.; He, Wei-Hong; Yuan, Dong-Xun; Yue, Ming-Liang; Yang, Ting-Lu

    2014-02-01

    New conodont samples have been systematically collected at high stratigraphic resolution from the upper part of the Longtan Formation through to the lower part of the Yelang Formation at the Zhongzhai section, southwestern Guizhou Province, South China, in an effort to verify the first local occurrence of Hindeodus parvus in relation to the Permian-Triassic boundary at this section. The resampled conodont fauna from the Permian-Triassic boundary interval comprises five identified species and two undetermined species in Hindeodus and Clarkina. Most importantly, the first local occurrence of Hindeodus parvus is found for the first time from the bottom of Bed 28a, 18 cm lower than the previously reported first local occurrence of this species at this section. Considering the previously accepted PTB at the Zhongzhai section, well calibrated by conodont biostratigraphy, geochronology and carbon isotope chemostratigraphy, this lower (earlier) occurrence of H. parvus suggests that this critical species could occur below the Permian-Triassic boundary. As such, this paper provides evidence that (1) the first local occurrences of H. parvus are diachronous in different sections with respect to the PTB defined by the First Appearance Datum (FAD) of this species at its GSSP section in Meishan, China and that (2) the lower stratigraphic range of H. parvus should now be extended to latest Permian.

  5. Behavior of carbonate shelf communities in the Upper Triassic of Nevada: Evidence of impact mediated faunal turnover

    SciTech Connect

    Hogler, J.A. (Univ. of California, Berkeley, CA (United States). Museum of Paleontology)

    1993-04-01

    The carbonate shelf sediments of the Luning and Gabbs Formations of Nevada span the last several million years of the Triassic. This richly fossiliferous sequence provides a relatively continuous record of benthic community behavior during a long interval of global biotic turnover. Upper Carnian-Lower Norian and Upper Norian sea floors in this region were inhabited by a variety of invertebrate communities, all of them mollusc-dominated. Across a range of offshore shelf to basinal environments and throughout repeated community replacements, the most abundant and diverse taxa were infaunal and epifaunal bivalves and ammonites. The sequence of Upper Triassic molluscan communities was interrupted by a Lower or Middle Norian interval of brachiopod-dominated faunas. Although preserved in similar offshore carbonate shelf sediments, these communities are nearly devoid of the infaunal bivalves and ammonites that characterize both older and younger assemblages in the section. This pattern, of a temporary replacement of molluscan communities by brachiopod faunas, mimics that reported for some shelf assemblages across the Cretaceous-Tertiary boundary. That brief resurgence of brachiopods is linked to a sharp drop in marine primary productivity, which suggests that a disruption of planktonic food chains may also have occurred early in the Norian. The timing and pattern of Carnian-Norian faunal and physical events and their resemblance to K/T sequences are consistent with the proposal that an asteroid impact played a role in the Upper Triassic faunal transition.

  6. Ophiuroids discovered in the middle triassic hypersaline environment.

    PubMed

    Salamon, Mariusz A; Nied?wiedzki, Robert; Lach, Rafa?; Brachaniec, Tomasz; Gorzelak, Przemys?aw

    2012-01-01

    Echinoderms have long been considered to be one of the animal phyla that is strictly marine. However, there is growing evidence that some recent species may live in either brackish or hypersaline environments. Surprisingly, discoveries of fossil echinoderms in non-(open)marine paleoenvironments are lacking. In Wojkowice Quarry (Southern Poland), sediments of lowermost part of the Middle Triassic are exposed. In limestone layer with cellular structures and pseudomorphs after gypsum, two dense accumulations of articulated ophiuroids (Aspiduriella similis (Eck)) were documented. The sediments with ophiuroids were formed in environment of increased salinity waters as suggested by paleontological, sedimentological, petrographical and geochemical data. Discovery of Triassic hypersaline ophiuroids invalidates the paleontological assumption that fossil echinoderms are indicators of fully marine conditions. Thus caution needs to be taken when using fossil echinoderms in paleoenvironmental reconstructions. PMID:23185442

  7. Geologic Time Scale 2010 1 Minority Science Programs School of Biological Sciences University of California, Irvine

    E-print Network

    Rose, Michael R.

    ­ University of California, Irvine Name: TEACHER'S NOTES Period: ____ Purpose/Objectives: As a class, you of California, Irvine Major Events Table: Era Period Event Date (million years ago) Distance (meters extinctions) 245 2.45 Mesozoic Triassic First dinosaurs 225 2.25 Mesozoic Jurassic First mammals 200 2

  8. Paleomagnetic and Geological Implications of Magnetic Properties of the Triassic Diabase of Southeastern Pennsylvania

    Microsoft Academic Search

    M. E. Beck

    1965-01-01

    Preliminary measurements of magnetic properties of Triassic diabase in south- eastern Pennsylvania imply a Triassic geomagnetic pole in central Siberia, at 62øN, 105øE. This pole is virtually identical to that obtained from paleomagnetic studies of rocks of similar age in New Jersey and Arizona. A North American Triassic pole, the mean of six independent determinations, is located at 62øN, 101øE.

  9. Joint time-scale and TDOA estimation: analysis and fast approximation

    Microsoft Academic Search

    Y. T. Chan; K. C. Ho

    2005-01-01

    Relative motion (rm) between a signal source and a receiver causes a time scaling of the signal arriving at the receiver. When estimating the time-difference-of-arrival (TDOA) of a signal at two receivers, time scaling, when not properly accounted for, can introduce a bias that could dominate the estimation errors. Segmentization processing cannot reduce this bias. Following the derivation of the

  10. Scale-Invariant Extinction Time Estimates for Some Singular Diffusion Equations

    E-print Network

    Scale-Invariant Extinction Time Estimates for Some Singular Diffusion Equations Yoshikazu Giga that the solution becomes identically zero in finite time. We prove scale-invariant estimates for the extinction and q > 1). Our goal is to prove finite-time extinction, i.e. to show that the solution becomes

  11. Time-frequency scaling transformation of the phonocardiogram based of the matching pursuit method

    Microsoft Academic Search

    Xuan Zhang; Louis-Gilles Durand; Lotfi Senhadji; Howard C. Lee; Jean-Louis Coatrieux

    1998-01-01

    A time-frequency scaling transformation based on the matching pursuit (MP) method is developed for the phonocardiogram (PCG). The MP method decomposes a signal into a series of time-frequency atoms by using an iterative process. The modification of the time scale of the PCG can be performed without perceptible change in its spectral characteristics. It is also possible to modify the

  12. Structure and dating errors in the geologic time scale and periodicity in mass extinctions

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.

    1989-01-01

    Structure in the geologic time scale reflects a partly paleontological origin. As a result, ages of Cenozoic and Mesozoic stage boundaries exhibit a weak 28-Myr periodicity that is similar to the strong 26-Myr periodicity detected in mass extinctions of marine life by Raup and Sepkoski. Radiometric dating errors in the geologic time scale, to which the mass extinctions are stratigraphically tied, do not necessarily lessen the likelihood of a significant periodicity in mass extinctions, but do spread the acceptable values of the period over the range 25-27 Myr for the Harland et al. time scale or 25-30 Myr for the DNAG time scale. If the Odin time scale is adopted, acceptable periods fall between 24 and 33 Myr, but are not robust against dating errors. Some indirect evidence from independently-dated flood-basalt volcanic horizons tends to favor the Odin time scale.

  13. Atmospheric methane injection caused end-Triassic mass extinction

    Microsoft Academic Search

    Micha Ruhl; Nina R. Bonis; Gert-Jan Reichart; Jaap S. Sinninghe Damsté; Wolfram M. Kürschner

    2010-01-01

    The end-Triassic mass extinction (~201.5 Ma), marked by major terrestrial ecosystem changes and a 50% loss in marine biodiversity, coincides with a distinct negative perturbation in marine C-isotope records. These events have been attributed to the onset of intensified volcanic activity in the Central Atlantic Magmatic Province (CAMP), the largest igneous province on earth. However, global carbon cycle disruption has

  14. A unique geochemical record at the Permian\\/Triassic boundary

    Microsoft Academic Search

    William T. Holser; Hans-Peter Schoenlaub; Peter Klein; Moses Attrep Jr.; Klaus Boeckelmann; Mordeckai Magaritz; Charles J. Orth; Alois Fenninger; Catherine Jenny; Martin Kralik; Hermann Mauritsch; Edwin Pak; Josef-Michael Schramm; Karl Stattegger; Rupert Schmöller

    1989-01-01

    A 330-m core drilled through the marine Permian\\/Triassic boundary in the Austrian Carnic Alps has been used to make closely correlated studies of geochemistry, petrography, and paleontology across that boundary. The isotope shifts and metal concentrations are found to be extended, multiple, and complex, and do not resemble those seen at the Cretaceous\\/Tertiary boundary. Both the carbon isotope shifts and

  15. A review of selected triassic to Early Cretaceous ferns

    Microsoft Academic Search

    William D. Tidwell; Sidney R. Ash

    1994-01-01

    After becoming nearly extinct during the Permian, the ferns began a slow recovery during the Triassic as the climate of the\\u000a earth moderated. As a result, a considerable number and variety were present and widely distributed during the Jurassic and\\u000a Early Cretaceous. However, with the rapid expansion of the angiosperms during the Late Cretaceous, the ferns once again became\\u000a reduced

  16. Paleomagnetism of Upper Triassic Diabase from Southeastern Pennsylvania: Further Results

    Microsoft Academic Search

    1972-01-01

    Seventy-eight reliable sites in Upper Triassic diabase from southeastern Pennsylvania yield a pleomagnetic pole at 62.0øN, 104.5øE, about 0.5 ø from an earlier pole calculation based on a preliminary study of 20 sites. Site poles have a Fisherian distribution, with an angular standard deviation of 7.4 ø , considerably less than the dispersion predicted by models based on the present

  17. The Paleomagnetism of a Triassic Diabase Dike in Nova Scotia

    Microsoft Academic Search

    A. Larochelle; R. K. Wanless

    1966-01-01

    The paleomagnetism of a 110-km-long diabase dike in the southern part of Nova Scotia has been studied. A potassium-argon whole-rock age determination has confirmed the Triassic age assignment to the dike rocks. The magnetic stability and other magnetic properties of the rocks were examined, and the presence of a stable component was established. An analysis of the palcomagnetic data establishes

  18. Furculae in the Late Triassic theropod dinosaur Coelophysis bauri

    Microsoft Academic Search

    Larry F. Rinehart; Spencer G. Lucas; Adrian P. Hunt

    2007-01-01

    Furculae have been identified in many dinosaurs and are synapomorphic in some clades (e.g., dromaeosaurids). All coelophysid\\u000a dinosaurs exceptCoelophysis bauri have been shown to possess furculae. To date, the oldest well-documented furculae have been those of the Early Jurassic coelophysids,Coelophysis kayentakatae andCoelophysis rhodesiensis. The confirmation of furculae in Apachean-agedC. bauri further documents appearance of these elements in the Late Triassic

  19. Computational methods for time-scale analysis of nonlinear dynamical systems

    Microsoft Academic Search

    Shawn Iravanchy

    2003-01-01

    Knowledge of the time-scale structure of a smooth finite dimensional nonlinear dynamical system provides the opportunity for model decomposition, if there are two or more disparate time-scales. A few benefits of such model decomposition are simplified control design and analysis and reduced computational effort in simulation. Singular perturbation theory provides the tools necessary to analyze and decompose a multiple time-scale

  20. The characteristic time scale for basin hydrological response using radar data

    NASA Astrophysics Data System (ADS)

    Morin, Efrat; Enzel, Yehouda; Shamir, Uri; Garti, Rami

    2001-10-01

    The transformation of rainfall into runoff at a basin outlet is the combined effect of many hydrological processes, which occur at a wide range of spatial and temporal scales. However, determining the scale of the combined hydrological response of the basin is still problematic and concepts for its definition are yet to be identified. In this paper high-resolution meteorological radar data are used for the determination of a characteristic temporal scale for the hydrological response of the basin — the 'response time scale' (T s?). T s? is defined as the time scale at which the pattern of the time-averaged radar rainfall hietograph is most similar to the pattern of the measured outlet runoff hydrograph. The existence of such similarity at a relatively stable time scale for a specific basin indicates that it is an intrinsic property of the basin and is related to its hydrological response. The identification of the response time scale is carried out by analysis of observations only, without assuming a specific rainfall-runoff model. T s? is examined in four small basins (10-100 km 2) in Israel. The spatial scale is assumed as the entire basin. For all analyzed basins a stable response time scale is identified. Relatively short time scales are found for the urban and arid basins (15-30 min), while for the rural basins longer time scale are identified (90-180 min). The issues of relationship between the response time scale and basin properties and modeling at the response time scale have yet to be determined.

  1. Time resolved single photon imaging in Nanometer Scale CMOS technology 

    E-print Network

    Richardson, Justin Andrew

    2010-06-28

    Time resolved imaging is concerned with the measurement of photon arrival time. It has a wealth of emerging applications including biomedical uses such as fluorescence lifetime microscopy and positron emission tomography, ...

  2. Development of Real-time Closed-loop Control Algorithms for Grid-scale Battery

    E-print Network

    i Development of Real-time Closed-loop Control Algorithms for Grid-scale Battery Energy ................................................................... 17 3.3. Overview of Control Modes ..................................................................................... 19 5. Instrumentation

  3. Scaling up Dynamic Time Warping to Massive Dataset

    Microsoft Academic Search

    Eamonn J. Keogh; Michael J. Pazzani

    1999-01-01

    There has been much recent interest in adapting da ta mining algorithms to time series databases. Many of these algorithms nee d to compare time series. Typically some variation or extension of Euclidean distance is used. However, as we demonstrate in this paper, Euclidean distance can b e an extremely brittle distance measure. Dynamic time warping (DTW) has been suggested

  4. Increased Atmospheric SO2 Detected from Changes in Leaf Physiognomy across the Triassic–Jurassic Boundary Interval of East Greenland

    PubMed Central

    Bacon, Karen L.; Belcher, Claire M.; Haworth, Matthew; McElwain, Jennifer C.

    2013-01-01

    The Triassic–Jurassic boundary (Tr–J; ?201 Ma) is marked by a doubling in the concentration of atmospheric CO2, rising temperatures, and ecosystem instability. This appears to have been driven by a major perturbation in the global carbon cycle due to massive volcanism in the Central Atlantic Magmatic Province. It is hypothesized that this volcanism also likely delivered sulphur dioxide (SO2) to the atmosphere. The role that SO2 may have played in leading to ecosystem instability at the time has not received much attention. To date, little direct evidence has been presented from the fossil record capable of implicating SO2 as a cause of plant extinctions at this time. In order to address this, we performed a physiognomic leaf analysis on well-preserved fossil leaves, including Ginkgoales, bennettites, and conifers from nine plant beds that span the Tr–J boundary at Astartekløft, East Greenland. The physiognomic responses of fossil taxa were compared to the leaf size and shape variations observed in nearest living equivalent taxa exposed to simulated palaeoatmospheric treatments in controlled environment chambers. The modern taxa showed a statistically significant increase in leaf roundness when fumigated with SO2. A similar increase in leaf roundness was also observed in the Tr–J fossil taxa immediately prior to a sudden decrease in their relative abundances at Astartekløft. This research reveals that increases in atmospheric SO2 can likely be traced in the fossil record by analyzing physiognomic changes in fossil leaves. A pattern of relative abundance decline following increased leaf roundness for all six fossil taxa investigated supports the hypothesis that SO2 had a significant role in Tr–J plant extinctions. This finding highlights that the role of SO2 in plant biodiversity declines across other major geological boundaries coinciding with global scale volcanism should be further explored using leaf physiognomy. PMID:23593262

  5. Increased atmospheric SO? detected from changes in leaf physiognomy across the Triassic-Jurassic boundary interval of East Greenland.

    PubMed

    Bacon, Karen L; Belcher, Claire M; Haworth, Matthew; McElwain, Jennifer C

    2013-01-01

    The Triassic-Jurassic boundary (Tr-J; ?201 Ma) is marked by a doubling in the concentration of atmospheric CO2, rising temperatures, and ecosystem instability. This appears to have been driven by a major perturbation in the global carbon cycle due to massive volcanism in the Central Atlantic Magmatic Province. It is hypothesized that this volcanism also likely delivered sulphur dioxide (SO2) to the atmosphere. The role that SO2 may have played in leading to ecosystem instability at the time has not received much attention. To date, little direct evidence has been presented from the fossil record capable of implicating SO2 as a cause of plant extinctions at this time. In order to address this, we performed a physiognomic leaf analysis on well-preserved fossil leaves, including Ginkgoales, bennettites, and conifers from nine plant beds that span the Tr-J boundary at Astartekløft, East Greenland. The physiognomic responses of fossil taxa were compared to the leaf size and shape variations observed in nearest living equivalent taxa exposed to simulated palaeoatmospheric treatments in controlled environment chambers. The modern taxa showed a statistically significant increase in leaf roundness when fumigated with SO2. A similar increase in leaf roundness was also observed in the Tr-J fossil taxa immediately prior to a sudden decrease in their relative abundances at Astartekløft. This research reveals that increases in atmospheric SO2 can likely be traced in the fossil record by analyzing physiognomic changes in fossil leaves. A pattern of relative abundance decline following increased leaf roundness for all six fossil taxa investigated supports the hypothesis that SO2 had a significant role in Tr-J plant extinctions. This finding highlights that the role of SO2 in plant biodiversity declines across other major geological boundaries coinciding with global scale volcanism should be further explored using leaf physiognomy. PMID:23593262

  6. A Novel Multiple-Time Scale Integrator for the Hybrid Monte Carlo Algorithm

    SciTech Connect

    Kamleh, Waseem [Special Research Centre for the Subatomic Structure of Matter and Department of Physics, University of Adelaide 5005 (Australia)

    2011-05-24

    Hybrid Monte Carlo simulations that implement the fermion action using multiple terms are commonly used. By the nature of their formulation they involve multiple integration time scales in the evolution of the system through simulation time. These different scales are usually dealt with by the Sexton-Weingarten nested leapfrog integrator. In this scheme the choice of time scales is somewhat restricted as each time step must be an exact multiple of the next smallest scale in the sequence. A novel generalisation of the nested leapfrog integrator is introduced which allows for far greater flexibility in the choice of time scales, as each scale now must only be an exact multiple of the smallest step size.

  7. The Triassic dicynodont Kombuisia (Synapsida, Anomodontia) from Antarctica, a refuge from the terrestrial Permian-Triassic mass extinction

    Microsoft Academic Search

    Jörg Fröbisch; Kenneth D. Angielczyk; Christian A. Sidor

    2010-01-01

    Fossils from the central Transantarctic Mountains in Antarctica are referred to a new species of the Triassic genus Kombuisia, one of four dicynodont lineages known to survive the end-Permian mass extinction. The specimens show a unique combination\\u000a of characters only present in this genus, but the new species can be distinguished from the type species of the genus, Kombuisia frerensis,

  8. An analytical framework for quantifying aquifer response time scales associated with transient boundary conditions

    NASA Astrophysics Data System (ADS)

    Jazaei, Farhad; Simpson, Matthew J.; Clement, T. Prabhakar

    2014-11-01

    A major challenge in studying coupled groundwater and surface-water interactions arises from the considerable difference in the response time scales of groundwater and surface-water systems affected by external forcings. Although coupled models representing the interaction of groundwater and surface-water systems have been studied for over a century, most have focused on groundwater quantity or quality issues rather than response time. In this study, we present an analytical framework, based on the concept of mean action time (MAT), to estimate the time scale required for groundwater systems to respond to changes in surface-water conditions. MAT can be used to estimate the transient response time scale by analyzing the governing mathematical model. This framework does not require any form of transient solution (either numerical or analytical) to the governing equation, yet it provides a closed form mathematical relationship for the response time as a function of the aquifer geometry, boundary conditions, and flow parameters. Our analysis indicates that aquifer systems have three fundamental time scales: (i) a time scale that depends on the intrinsic properties of the aquifer, (ii) a time scale that depends on the intrinsic properties of the boundary condition, and (iii) a time scale that depends on the properties of the entire system. We discuss two practical scenarios where MAT estimates provide useful insights and we test the MAT predictions using new laboratory-scale experimental data sets.

  9. New Geochemical and Isotopic Evidence for Igneous Activity at the Triassic-Jurassic Boundary: the Effects of Volcanism in the Central Atlantic Magmatic Province

    NASA Astrophysics Data System (ADS)

    Cohen, A. S.; Coe, A. L.

    2001-12-01

    Although the Triassic-Jurassic (T-J) boundary marks one of the `big five' extinction events of the Phanerozoic, the processes driving global change at that time remain obscure. The main contenders include substantial volcanic activity, large meteorite impacts, and major tectonic realignment. Recent results from high-precision Ar-Ar and U-Pb dating suggest that a major phase of volcanic activity, associated with the breakup of Pangea, started ~200 Ma ago in the so-called Central Atlantic magmatic province (Marzoli et al., Science 284, p. 616, 1999). However, it is often hard to accurately assess the global impact of this volcanic activity because of the difficulties in correlating igneous ages with the changes in the sedimentary successions which in practice define the position of the T-J boundary, and because of the difficulties in estimating the volume and extent of volcanic activity. In this study, we have adopted a new approach by determining the Mo, Re and platinum group element (PGE) abundances, and Os isotope compositions, of a suite of fully marine organic-rich mudrocks from three T-J boundary sections in the U.K. One of these sections (St. Audrie's Bay, Somerset) has been proposed as a candidate GSSP for the T-J boundary. The underlying rationale is that organic-rich mudrocks concentrate these elements from seawater, and reflect the particular geochemical and isotopic characteristics of seawater on a global scale at the time of mudrock deposition. Because the Re and PGE signatures of chondritic meteorites and terrestrial volcanism are distinctive, as are the signatures they impart to seawater, the patterns of these elements in well-preserved mudrock samples should help to define both the timing and nature of environmental change at the T-J boundary. Our new results show that Os abundances in marine mudrocks increased more than five-fold in the latest Triassic; Re abundances started to rise at the same time and had increased by up to 2 orders of magnitude in the earliest Jurassic. At the same time, the 187Os/188Os ratio of seawater (as indicated by the 187Os/188Os(i) ratio of the mudrocks) fell from a mean value of ~0.55 in the late Triassic to ~0.16 just before the T-J boundary. High levels of Re and unradiogenic Os characterise organic-rich mudrocks which were deposited during the ensuing 3-4 Ma of the earliest Jurassic (Cohen et al., EPSL 167, p.159, 1999). We attribute these substantial geochemical and isotopic changes in seawater to a sudden influx of large amounts of Re and unradiogenic Os derived from the hydrothermal alteration of volcanics erupted during the initial rifting of Pangea. These particular characteristics can not be readily attributed to the impact of a large chondritic or iron meteorite at that time. This assertion is further confirmed by preliminary Pt and Ir data, with Pt/Ir ratios indicative of crustal rather than meteoritic sources. Taken together, these results demonstrate that seawater Re-Os isotope characteristics and PGE abundance patterns can help to pinpoint and identify the timing of, and causes behind, episodes of major environmental change.

  10. A new Geologic Time Scale, with special reference to Precambrian and Neogene

    Microsoft Academic Search

    Felix M. Gradstein; James G. Ogg; Alan G. Smith; Wouter Bleeker; Lucas J. Lourens

    A Geologic Time Scale (GTS2004) is presented that inte- grates currently available stratigraphic and geochrono- logic information. Key features of the new scale are out- lined, how it was constructed, and how it can be further improved. The accompanying International Strati- graphic Chart, issued under auspices of the Interna- tional Commission on Stratigraphy (ICS), shows the cur- rent chronostratigraphic scale

  11. Effects induced by noncausality of scaling on robust stability analysis of discrete-time periodically time-varying systems

    Microsoft Academic Search

    Yohei Hosoe; Tomomichi Hagiwara

    2010-01-01

    This paper is concerned with robust stability analysis of discrete-time linear periodically time-varying (LPTV) systems. The well-known discrete-time lifting technique enables us to deal with LPTV systems as if they were linear time-invariant (LTI), and we can analyze the robust stability through the lifted (i.e., equivalent LTI) systems. Through such lifting treatment, the discrete-time causal\\/noncausal LPTV scaling can be naturally

  12. Global terrestrial biogeochemistry: Perturbations, interactions, and time scales

    SciTech Connect

    Braswell, B.H. Jr.

    1996-12-01

    Global biogeochemical processes are being perturbed by human activity, principally that which is associated with industrial activity and expansion of urban and agricultural complexes. Perturbations have manifested themselves at least since the beginning of the 19th Century, and include emissions of CO{sub 2} and other pollutants from fossil fuel combustion, agricultural emissions of reactive nitrogen, and direct disruption of ecosystem function through land conversion. These perturbations yield local impacts, but there are also global consequences that are the sum of local-scale influences. Several approaches to understanding the global-scale implications of chemical perturbations to the Earth system are discussed. The lifetime of anthropogenic CO{sub 2} in the atmosphere is an important concept for understanding the current and future commitment to an altered atmospheric heat budget. The importance of the terrestrial biogeochemistry relative to the lifetime of excess CO{sub 2} is demonstrated using dynamic, aggregated models of the global carbon cycle.

  13. Heterogenous scaling in interevent time of on-line bookmarking

    Microsoft Academic Search

    Peng Wang; Xiao-Yi Xie; Chi Ho Yeung; Bing-Hong Wang

    2010-01-01

    In this paper, we study the statistical properties of bookmarking behaviors\\u000ain Delicious.com. We find that the interevent time distributions of bookmarking\\u000adecays powerlike as interevent time increases at both individual and population\\u000alevel. Remarkably, we observe a significant change in the exponent when\\u000ainterevent time increases from intra-day to inter-day range. In addition,\\u000adependence of exponent on individual Activity

  14. Time scales of spike-train correlation for neural oscillators with common drive

    SciTech Connect

    Barreiro, Andrea K.; Shea-Brown, Eric; Thilo, Evan L. [Department of Applied Mathematics, University of Washington, P.O. Box 352420, Seattle, Washington 98195 (United States)

    2010-01-15

    We examine the effect of the phase-resetting curve on the transfer of correlated input signals into correlated output spikes in a class of neural models receiving noisy superthreshold stimulation. We use linear-response theory to approximate the spike correlation coefficient in terms of moments of the associated exit time problem and contrast the results for type I vs type II models and across the different time scales over which spike correlations can be assessed. We find that, on long time scales, type I oscillators transfer correlations much more efficiently than type II oscillators. On short time scales this trend reverses, with the relative efficiency switching at a time scale that depends on the mean and standard deviation of input currents. This switch occurs over time scales that could be exploited by downstream circuits.

  15. Facies analysis of Lofer cycles (Upper Triassic), in the Argolis Peninsula (Greece)

    NASA Astrophysics Data System (ADS)

    Pomoni-Papaioannou, F.

    The Upper Triassic carbonate sediments of Argolis Peninsula are part of the Upper Triassic-Lower Jurassic extensive and thick neritic carbonate formations (Pantokrator facies) that formed at the passive Pelagonian margin and are considered as Dachstein-type platform carbonates. Facies analysis of the Upper Triassic "Lofer-type" lagoonal-peritidal cycles in the Dhidimi area, proved that cycles, although mostly incomplete, were regressive shallowing-upward. The ideal elementary cyclothems are meter-scale in thickness and begin with a subtidal bed (Member C), represented by a peloidal dolostone with megalodonts (wackestone or packstone), being followed by a stromatolitic intertidal dolomitic mudstone and/or fenestral intertidal dolomitic mudstone (Member B) that is overlain by dolocrete (terrestrial stromatolites or pisoidic dolomite) or a supratidal "soil conglomerate" in red micritic matrix (Member A). Lofer-cycle boundaries are defined at the erosional surfaces and accordingly the Lofer cyclothems are unconformity-bounded units. Due to common post-depositional truncation of the subtidal and intertidal facies, the supratidal members prevail, being developed, in places, directly upon subaerial exposure surfaces (erosionally reduced cyclothems). Peritidal layers are characterized by a well-expressed lamination, sheet cracks, tepee structures, fenestral pores and karst dissolution cavities. The studied lagoonal-peritidal cycles are considered to have been deposited in a tidal-flat setting (inner platform), repeatedly exposed under subaerial conditions, in the context of a broader tropical rimmed platform. Although the studied area was tectonically active due to rift-activity and the autocyclic processes should also be taken in consideration, the great lateral correlatability of cycles, the facies shifting and the widespread erosion that resulted in superposition of supratidal-pedogenic facies directly upon subtidal members (subaerial erosional unconformity), indicating a sea-level drop, reflect allocyclic control via high-frequency eustatic sea-level oscillation (orbital forcing). Sediment deposition occurred during low-stand system tract (LST), that probably continued also in the transgressive system tract (TST) and reflects an overall sea-level fall. Under these conditions dissolution and cement precipitation episodes, as well development of paleosols and karsts, were triggered, during a relatively less arid interval.

  16. Nitrogen isotope chemostratigraphy across the Permian-Triassic boundary at Chaotian, Sichuan, South China

    NASA Astrophysics Data System (ADS)

    Saitoh, Masafumi; Ueno, Yuichiro; Nishizawa, Manabu; Isozaki, Yukio; Takai, Ken; Yao, Jianxin; Ji, Zhansheng

    2014-10-01

    Nitrogen isotopic compositions of upper Permian to lowermost Triassic rocks were analyzed at Chaotian in northern Sichuan, South China, in order to clarify changes in the oceanic nitrogen cycle around the Permian-Triassic boundary (P-TB) including the entire Changhsingian (Late Late Permian) prior to the extinction. The analyzed ca. 40 m thick interval across the P-TB at Chaotian consists of three stratigraphic units: the upper Wujiaping Formation, the Dalong Formation, and the lowermost Feixianguan Formation, in ascending order. The upper Wujiaping Formation, ca. 10 m thick, is mainly composed of dark gray limestone with diverse shallow-marine fossils such as calcareous algae and brachiopods, deposited on the shallow shelf. In contrast, the overlying Dalong Formation, ca. 25 m thick, is mainly composed of thinly bedded black mudstone and siliceous mudstone containing abundant radiolarians, deposited on the relatively deep slope/basin. Absence of bioturbation, substantially high total organic carbon contents (up to 15%), and abundant occurrence of pyrite framboids in the main part of the Dalong Formation indicate deposition under anoxic condition. The lowermost Feixianguan Formation, ca. 5 m thick, is composed of thinly bedded gray marl and micritic limestone with minor fossils such as ammonoids and conodonts, deposited on the relatively shallow slope. ?15NTN values are in positive values around +1 to +2‰ in the upper Wujiaping Formation implying denitrification and/or anammox in the ocean. ?15NTN values gradually decrease to -1‰ in the lower Dalong Formation and are consistently low (around 0‰) in the middle Dalong to lowermost Feixianguan Formation. No clear ?15NTN shift is recognized across the extinction horizon. The consistently low ?15NTN values suggest the enhanced nitrogen fixation in the ocean during the Changhsingian at Chaotian. Composite profiles based on previous and the present studies demonstrate the substantial ?15N variation on a global scale in the late Permian to earliest Triassic; a systematic ?15N difference by low and high latitudes is particularly clarified. Although the enhanced nitrogen fixation throughout the Changhsingian at Chaotian was likely a regional event in northwestern South China, the composite ?15N profiles imply that the sea area in which fixed nitrogen is depleted has gradually developed worldwide in the Changhsingian, possibly acting as a prolonged stress to shallow-marine biota.

  17. Invited review article: The statistical modeling of atomic clocks and the design of time scales.

    PubMed

    Levine, Judah; Ibarra-Manzano, O

    2012-02-01

    I will show how the statistical models that are used to describe the performance of atomic clocks are derived from their internal design. These statistical models form the basis for time scales, which are used to define international time scales such as International Atomic Time and Coordinated Universal Time. These international time scales are realized by ensembles of clocks at national laboratories such as the National Institute of Standards and Technology, and I will describe how ensembles of atomic clocks are characterized and managed. PMID:22380071

  18. Microsecond-scale timing precision in rodent trigeminal primary afferents.

    PubMed

    Bale, Michael R; Campagner, Dario; Erskine, Andrew; Petersen, Rasmus S

    2015-04-15

    Communication in the nervous system occurs by spikes: the timing precision with which spikes are fired is a fundamental limit on neural information processing. In sensory systems, spike-timing precision is constrained by first-order neurons. We found that spike-timing precision of trigeminal primary afferents in rats and mice is limited both by stimulus speed and by electrophysiological sampling rate. High-speed video of behaving mice revealed whisker velocities of at least 17,000°/s, so we delivered an ultrafast "ping" (>50,000°/s) to single whiskers and sampled primary afferent activity at 500 kHz. Median spike jitter was 17.4 ?s; 29% of neurons had spike jitter < 10 ?s. These results indicate that the input stage of the trigeminal pathway has extraordinary spike-timing precision and very high potential information capacity. This timing precision ranks among the highest in biology. PMID:25878266

  19. Microsecond-Scale Timing Precision in Rodent Trigeminal Primary Afferents

    PubMed Central

    Bale, Michael R.; Campagner, Dario; Erskine, Andrew

    2015-01-01

    Communication in the nervous system occurs by spikes: the timing precision with which spikes are fired is a fundamental limit on neural information processing. In sensory systems, spike-timing precision is constrained by first-order neurons. We found that spike-timing precision of trigeminal primary afferents in rats and mice is limited both by stimulus speed and by electrophysiological sampling rate. High-speed video of behaving mice revealed whisker velocities of at least 17,000°/s, so we delivered an ultrafast “ping” (>50,000°/s) to single whiskers and sampled primary afferent activity at 500 kHz. Median spike jitter was 17.4 ?s; 29% of neurons had spike jitter < 10 ?s. These results indicate that the input stage of the trigeminal pathway has extraordinary spike-timing precision and very high potential information capacity. This timing precision ranks among the highest in biology. PMID:25878266

  20. Simulating Human Cardiac Electrophysiology on Clinical Time-Scales

    PubMed Central

    Niederer, Steven; Mitchell, Lawrence; Smith, Nicolas; Plank, Gernot

    2011-01-01

    In this study, the feasibility of conducting in silico experiments in near-realtime with anatomically realistic, biophysically detailed models of human cardiac electrophysiology is demonstrated using a current national high-performance computing facility. The required performance is achieved by integrating and optimizing load balancing and parallel I/O, which lead to strongly scalable simulations up to 16,384 compute cores. This degree of parallelization enables computer simulations of human cardiac electrophysiology at 240 times slower than real time and activation times can be simulated in approximately 1?min. This unprecedented speed suffices requirements for introducing in silico experimentation into a clinical workflow. PMID:21516246

  1. A Comparison of Remineralization Time and Space Scales for Sinking Particles at Station ALOHA

    E-print Network

    Buesseler, Ken

    A Comparison of Remineralization Time and Space Scales for Sinking Particles at Station ALOHA A Comparison of Remineralization Time and Space Scales for Sinking Particles at Station ALOHA Thanks to N 158º W ALOHA Dust Flux (g m-2 y-1) bSi/Cinorg deep trap (mole) Deep POC flux (g m-2 y-1) f

  2. Multiple TimeScales in Classical and QuantumClassical Molecular Dynamics

    E-print Network

    Reich, Sebastian

    Multiple Time­Scales in Classical and Quantum­Classical Molecular Dynamics Sebastian Reich \\Lambda October 1, 1998 Abstract The existence of multiple time scales in molecular dynamics poses interesting. The discussion focuses on classical molecular dynamics (CMD) with fast bond stretching and bending modes and the

  3. Existence results for periodic solutions of integro - dynamic equations on time scales

    Microsoft Academic Search

    Murat Adivar

    Using topological degree method and Schaefer's fixe d point theorem, we deduce the existence of periodic solutions of nonlinear sy stem of integro-dynamic equations on periodic time scales. Furthermore, we provide several applications to scalar equations, where we develop a time scale ana logue of Lyapunov's direct method. Therefore, we improve and generalize the corresponding results in (T. A. Burton,

  4. Two-Time Scale Fuzzy Logic Controller With Vibration Stabilizer for Robot Manipulators with Oscillatory Bases

    Microsoft Academic Search

    J. Lin; Z.-Z. Huang; P. H. Huang

    2007-01-01

    This paper deals with active damping control problems of robot manipulators with oscillatory bases. A first investigation of two-time scale fuzzy logic controller with stabilizer for such structures has been proposed, where the dynamics of a robotic system is strongly affected by disturbances due to the base oscillation. Under the assumption of two-time scale, its stability and design procedures are

  5. Non-Linear Model Reduction for Metabolic Networks with Multiple Time-Scales

    Microsoft Academic Search

    Ziomara P. Gerdtzen; Prodromos Daoutidis; Wei-Shou Hu

    2005-01-01

    We present a method for obtaining non-stiff nonlinear reduced-order models for metabolic networks, which exhibit dynamics in multiple time scales. The method is based on the successive application of singular perturbation arguments, starting from the fastest time scale and proceeding to the slowest one. The method is successfully applied to a detailed model of central carbon metabolism in human erythrocytes

  6. The NBS-A Time Scale-Its Generation and Dissemination

    Microsoft Academic Search

    J. A. Barnes; D. H. Andrews; D. W. Allan

    1965-01-01

    In conjunction with the United States Frequency Standard (USFS) located at the National Bureau of Standards, Boulder Laboratories, two time scales have been established. The NBS-A time scale is referenced to the USFS in accordance with the definition of the atomic second as adopted by the 12th General Conference of Weights and Measures in October, 1964. The epoch of this

  7. Characteristic Variations of Sea Surface Temperature with Multiple Time Scales in the North Pacific

    Microsoft Academic Search

    Youichi Tanimoto; Kimio Hanawa; Yoshiaki Toba; Naoto Iwasaka

    1993-01-01

    Temporal evolution and spectral structure of sea surface temperature (SST) anomalies in the North Pacific over the last 37 years are investigated on the three characteristic time scales: shorter than 24 months (HF), 24-60 months (ES), and longer than 60 months (DC). The leading empirical-orthogonal function (EOF) for the DC time scale is characterized by a zonally elongated monopole centered

  8. Time Scale Decomposition of a Class of Generalized Stochastic Petri Net Models

    Microsoft Academic Search

    Hany H. Ammar; S. M. Rezaul Islam

    1989-01-01

    A time-scale decomposition (TSD) algorithm of a class of generalized stochastic Petri net (GSPN) models of systems comprising activities whose duration differ by orders of magnitude is presented. The GSPN model of a system can be decomposed into a hierarchical sequence of aggregated subnets, each of which is valid at a certain time scale. These smaller subnets are solved in

  9. Time scale and intensity dependency in multiplicative cascades for temporal rainfall disaggregation

    E-print Network

    Selker, John

    Time scale and intensity dependency in multiplicative cascades for temporal rainfall disaggregation in rainfall. The elemental MRC model parameter is the cascade weight, which determines how rainfall at one density of these weights may vary with both time scale and rainfall intensity, nearly all previous studies

  10. Observation of quantum particles on a large space-time scale

    Microsoft Academic Search

    L. J. Landau

    1994-01-01

    A quantum particle observed on a sufficiently large space-time scale can be described by means of classical particle trajectories. The joint distribution for large-scale multiple-time position and momentum measurements on a nonrelativistic quantum particle moving freely inRv is given by straight-line trajectories with probabilities determined by the initial momentum-space wavefunction. For large-scale toroidal and rectangular regions the trajectories are geodesics.

  11. Modeling for scaling to humans: Time to get serious

    SciTech Connect

    Thomas, R.G. (Department of Energy, Washington, DC (USA))

    1989-01-01

    The subject matter for this 26th Annual Hanford Life Sciences Symposium evolved from the deliberations of a Task Group on Modeling for Scaling to Humans, which was established in January 1986 through the efforts of the Office of Health and Environmental Research of the Department of Energy (OHER/DOE). Several laboratories that utilize animals in radiobiological research sponsored by the OHER/DOE were extensively reviewed in the spring of 1985, and, as a result, OHER recommended establishment of eight task groups designed for selected purposes. The current membership of the Task Group on Modeling for Scaling to Humans is presented. Dr. James A. Mewhinney of the Lovelace Inhalation Toxicology Research Institute has been Chairman since these Task Groups were established. Ms. Judy Mahaffey of Battelle. Pacific Northwest Laboratories served as chairperson for this symposium, and the Task Group membership has served as the Program Committee. The OHER/DOE thanks all of them for their work as members of the Task Group as well as for their arranging such a potentially productive and informative meeting.

  12. Late Triassic rifting and Jurassic-Cretaceous passive margin development of the Southern Neotethys: evidence from the Ad?yaman area, SE Turkey

    NASA Astrophysics Data System (ADS)

    Robertson, A. H. F.; Parlak, O.; Y?ld?r?m, N.; Dumitrica, P.; Tasl?, K.

    2015-05-01

    Evidence of rifting and continental break-up to form the S Neotethys is found within the volcanic-sedimentary Koçali Complex. This is a folded, thrust-imbricated succession that includes lavas, volcaniclastic sediments, pelagic carbonates, radiolarites and manganiferous deposits. Interbedded ribbon cherts contain radiolarians of Late Triassic to Late Jurassic age. The lower part of the succession of Mid?-Late Triassic age (Tarasa Formation) is dominated by enriched mid-ocean ridge basalt (E-MORB). The overlying Late Triassic to Mid-Jurassic interval (Konak Formation) is characterised by intercalations of ocean island basalt and E-MORB. Taking account of structural position, the basalts erupted within the outer part of a continent-ocean transition zone. Continental break-up probably occurred during the Late Triassic (Carnian-Norian). Early to Mid-Jurassic lavas and volcaniclastic sediments record volcanism probably after continental break-up. In addition, the Karadut Complex is a broken formation that is located at a relatively low structural position just above the Arabian foreland. Pelagic carbonates, redeposited carbonates and radiolarites predominate. Radiolarians are dated as Early to Mid-Jurassic and Late Cretaceous in age. The pelagic carbonates include planktic foraminifera of Late Cretaceous age. The Karadut Complex resulted from the accumulation of calcareous gravity flows, pelagic carbonate and radiolarites in a relatively proximal, base-of-slope setting. After continental break-up, MORB and ophiolitic rocks formed within the S Neotethys further north. Tectonic emplacement onto the Arabian platform took place by earliest Maastrichtian time. Regional interpretation is facilitated by comparisons with examples of Triassic rifting and continental break-up in the eastern Mediterranean region and elsewhere.

  13. Development of lower Triassic wrinkle structures: implications for the search for life on other planets.

    PubMed

    Mata, Scott A; Bottjer, David J

    2009-11-01

    Wrinkle structures are microbially mediated sedimentary structures that are a common feature of Proterozoic and earliest Phanerozoic siliciclastic seafloors on Earth and occur only rarely in post-Cambrian strata. These macroscopic microbially induced sedimentary structures are readily identifiable at the outcrop scale, and their recognition on other planetary bodies by landed missions may suggest the presence of past microbial life. Wrinkle structures of the Lower Triassic (Spathian) Virgin Limestone Member of the Moenkopi Formation in the western United States record an occurrence of widespread microbialite formation in the wake of the end-Permian mass extinction, the largest biotic crisis of the Phanerozoic. Wrinkle structures occur on proximal sandy tempestites deposited within the offshore transition. Storm layers appear to have been rapidly colonized by microbial mats and were subsequently buried by mud during fair-weather conditions. Wrinkle structures exhibit flat-topped crests and sinuous troughs, with associated mica grains oriented parallel to bedding, suggestive of trapping and binding activity. Although Lower Triassic wrinkle structures postdate the widespread occurrence of these features during the Proterozoic and Cambrian, they exhibit many of the same characteristics and environmental trends, which suggests a conservation of microbial formational and preservational processes in subtidal siliciclastic settings on Earth from the Precambrian into the Phanerozoic. In the search for extraterrestrial life, it may be these conservative characteristics that prove to be the most useful and robust for recognizing microbial features on other planetary bodies, and may add to an ever-growing foundation of knowledge for directing future explorations aimed at seeking out macroscopic microbial signatures. PMID:19968465

  14. Return to Coalsack Bluff and the Permian Triassic boundary in Antarctica

    Microsoft Academic Search

    Gregory J. Retallack; Tara Greaver; A. Hope Jahren

    2007-01-01

    Coalsack Bluff was the first discovery site in Antarctica for the latest Permian to earliest Triassic reptile Lystrosaurus. This together with discovery of Permian Glossopteris leaves during the heroic age of Antarctic exploration, indicated not only that Antarctica was part of Gondwanaland, but also that Antarctic rocks recorded faunas from the greatest of all mass extinctions at the Permian Triassic

  15. GR Focus Review Impacts of global warming on Permo-Triassic terrestrial ecosystems

    E-print Network

    Benton, Michael

    GR Focus Review Impacts of global warming on Permo-Triassic terrestrial ecosystems Michael J Available online 31 December 2012 Keywords: Mass extinction Permian Triassic Continental Terrestrial of the end-Permian mass extinction on continental habitats and on terrestrial life. Current work suggests

  16. Fungal abundance spike and the Permian^Triassic boundary in the Karoo Supergroup (South Africa)

    E-print Network

    Fungal abundance spike and the Permian^Triassic boundary in the Karoo Supergroup (South Africa extinction of marine species and terrestrial vertebrates and plants is associated with the Permian^Triassic boundary (V251 Ma). The extinction interval is also marked by the disappearance of most Late Permian

  17. A CYNODONT FROM THE UPPER TRIASSIC OF EAST GREENLAND: TOOTH REPLACEMENT AND DOUBLE-ROOTEDNESS

    E-print Network

    Shapiro, Mike

    A CYNODONT FROM THE UPPER TRIASSIC OF EAST GREENLAND: TOOTH REPLACEMENT AND DOUBLE the Upper Triassic Fleming Fjord Formation of East Greenland possesses double-rooted postcanine teeth Fjord For- mation of Jameson Land, East Greenland, preserves a diverse fossil vertebrate fauna

  18. A new chronology for the end-Triassic mass extinction M.H.L. Deenen a,

    E-print Network

    Utrecht, Universiteit

    from the Triassic to Jurassic Period, initiating the `Age of the dinosaurs', approximately 200 Ma. This event closely coincides with a period of extensive volcanism in the Central Atlantic Magmatic Province. The Triassic­Jurassic (T­J) boundary is recently proposed in the marine record at the first occurrence datum

  19. A critical re?evaluation of the Late Triassic dinosaur taxa of North America

    Microsoft Academic Search

    Sterling J. Nesbitt; Randall B. Irmis; William G. Parker

    2007-01-01

    The North American Triassic dinosaur record has been repeatedly cited as one of the most complete early dinosaur assemblages. The discovery of Silesaurus from Poland and the recognition that Herrerasaurus and Eoraptor may not be theropods have forced a re?evaluation of saurischian and theropod synapomorphies. Here, we re?evaluate each purported Triassic dinosaur from North America on a specimen by specimen

  20. Landscape ecological shift at the Permian-Triassic boundary in Antarctica

    Microsoft Academic Search

    G. J. Retallack; E. S. Krull

    1999-01-01

    Palaeosols across the Permian?Triassic boundary in Antarctica provide evidence of a marked change in ecosystems at this greatest of all extinctions in the history of life on Earth. The boundary can now be recognised from evidence of carbon isotopic (?C) stratigraphy, reptiles of the earliest Triassic Lystrosaurus zone, and Late Permian glossopterid fructifications and pollen. The boundary is a profound

  1. Analysis of Two Time Scale Property of Singularly Perturbed System on Chaotic Attractor

    E-print Network

    Mozhgan Mombeini; Ali Khaki Sedigh; Mohammad Ali Nekoui

    2012-05-17

    The idea that chaos could be a useful tool for analyze nonlinear systems considered in this paper and for the first time the two time scale property of singularly perturbed systems is analyzed on chaotic attractor. The general idea introduced here is that the chaotic systems have orderly strange attractors in phase space and this orderly of the chaotic systems in subscription with other classes of systems can be used in analyses. Here the singularly perturbed systems are subscripted with chaotic systems. Two time scale property of system is addressed. Orderly of the chaotic attractor is used to analyze two time scale behavior in phase plane.

  2. Recovery from the most profound mass extinction of all time

    PubMed Central

    Sahney, Sarda; Benton, Michael J

    2008-01-01

    The end-Permian mass extinction, 251 million years (Myr) ago, was the most devastating ecological event of all time, and it was exacerbated by two earlier events at the beginning and end of the Guadalupian, 270 and 260?Myr ago. Ecosystems were destroyed worldwide, communities were restructured and organisms were left struggling to recover. Disaster taxa, such as Lystrosaurus, insinuated themselves into almost every corner of the sparsely populated landscape in the earliest Triassic, and a quick taxonomic recovery apparently occurred on a global scale. However, close study of ecosystem evolution shows that true ecological recovery was slower. After the end-Guadalupian event, faunas began rebuilding complex trophic structures and refilling guilds, but were hit again by the end-Permian event. Taxonomic diversity at the alpha (community) level did not recover to pre-extinction levels; it reached only a low plateau after each pulse and continued low into the Late Triassic. Our data showed that though there was an initial rise in cosmopolitanism after the extinction pulses, large drops subsequently occurred and, counter-intuitively, a surprisingly low level of cosmopolitanism was sustained through the Early and Middle Triassic. PMID:18198148

  3. Triassic arc-derived detritus in the Triassic Karakaya accretionary complex was not derived from either the S Eurasian margin (Istanbul terrane) or the N Gondwana margin (Taurides)

    NASA Astrophysics Data System (ADS)

    Ustaömer, Timur; Ayda Ustaömer, Petek; Robertson, Alastair H. F.; Gerdes, Axel; Zulauf, Gernold

    2014-05-01

    We present new U-Pb zircon source age data for Upper Triassic sandstones of the Istanbul Terrane (S Eurasian margin) and also for Triassic sandstones of the Taurides (N Gondwana margin). The main aim is to detect and quantify the contribution of Triassic magmatism as detritus to either of these crustal blocks. This follows the recent discovery of a Triassic magmatic arc source for the Triassic sandstones of the Palaeotethyan Karakaya subduction-accretion complex (Ustaömer et al. 2013; this meeting). Carboniferous (Variscan) zircon grains also form a significant detrital population, plus several more minor populations. Six sandstone samples were studied, two from the ?stanbul Terrane (Bak?rl?k?ran Formation of the Kocaeli Triassic Basin) and four from the Tauride Autochthon (latest Triassic Üzümdere Formation and Mid-Triassic Kas?mlar Formations; Bey?ehir region). Detrital zircon grains were dated by the laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS) U-Pb method at Goethe University, Frankfurt. Our results do not reveal Triassic detritus in the Üzümdere Formation. The U-Pb age of the analysed zircon grains ranges from 267 Ma to 3.2 Ga. A small fraction of Palaeozoic zircons are Permian (267 to 296 Ma), whereas the remainder are Early Palaeozoic. Ordovician grains (4%) form two age clusters, one at ca. 450 Ma and the other at ca. 474 Ma. Cambrian-aged grains dominate the zircon population, while the second largest population is Ediacaran (576 to 642 Ma). Smaller populations occur at 909-997 Ma, 827-839 Ma, 1.8-2.0 Ga and 2.4-2.6 Ga. The sandstones of the Kas?mlar Formation have similar zircon age cluster to those of the somewhat younger Üzümdere Formation, ranging from 239 Ma to 2.9 Ga. A few grains gave Anisian ages. Cambrian zircon grains are less pronounced than in the Kas?mlar Formation compared to the Üzümdere Formation. The detrital zircon record of Tauride sandstones, therefore, not indicates significant contribution of Triassic or Carboniferous (Variscan) arc sources, in marked contrast to those of the Triassic Karakaya subduction complex. In comparison, the ages of the analysed zircons in the Upper Triassic sandstones of the Istanbul Terrane range from 294 Ma to 3.1 Ga. Triassic zircons are again absent, while Variscan-aged zircons (294 to 339 Ma) dominate the zircon population. Additional zircon populations are dated at 554 to 655 Ma, 0.9 to 1.2 Ga, 1.5 Ga, 1.65 Ga, 2.0 to 2.15 and 2.5 to 2.8 Ga. The Precambrian zircon age spectra are compatible with derivation from an Avalonian/Amazonian/Baltic crustal provenance. In summary, there is no evidence in either the Triassic sandstones of the ?stanbul Terrane or of the Taurides of the Triassic magmatic arc source that dominates the Triassic Karakaya subduction-accretion complex. Where then was the source of the Karakaya arc detritus? A likely option is that the Karakaya subduction-accretion complex is an exotic terrane that was detached from a source magmatic arc and displaced to its present location, probably prior the initial deposition of the Early Jurassic cover sediments. This study was supported by TUBITAK, Project No: 111R015

  4. Time scales in the JPL and CfA ephemerides

    Microsoft Academic Search

    E. M. Standish

    Over the past decades, the IAU has repeatedly at- tempted to correct its definition of the basic fundamental argu- ment used in the ephemerides. Finally, they have defined a time system which is physically possible, according to the accepted standard theory of gravitation: TCB (\\

  5. Web traffic modeling at finer time scales and performance implications

    Microsoft Academic Search

    Cathy H. Xia; Zhen Liu; Mark S. Squillante; Li Zhang; Naceur Malouch

    2005-01-01

    The performance of Web sites continues to be an important research topic. Such studies are invariably based on the access logs from the servers comprising the Web site. A problem with existing access logs is the coarse granularity of the timestamps, e.g., arrival times. In this study we demonstrate and quantify the significant differences in performance obtained under diverse assumptions

  6. Time Sequence Summarization to Scale Up Chronology-dependent Applications

    E-print Network

    Paris-Sud XI, Université de

    ]: Clustering--Algorithms General Terms Algorithms, Experimentation, Performance, Theory Keywords Time sequences, Summarization, Taxonomies, Clustering Permission to make digital or hard copies of all or part of this work to browse through companies' stock values while visualizing background information about the companies

  7. Space-time scales of internal waves: A progress report

    Microsoft Academic Search

    Christopher Garrett; Walter Munk

    1975-01-01

    We present a revised model for the distribution of internal wave energy in wave number frequency space. The model is empirical, guided by the following measurements: moored spectra and moored coherences for horizontal and vertical separations (MS, MHC, MVC as functions of frequency), towed spectra and towed vertical and time-lagged coherences (TS, TVC, TLC as functions of horizontal wave number),

  8. Modeling the uncertainty associated with the observation scale of space/time natural processes

    NASA Astrophysics Data System (ADS)

    Lee, S.; Serre, M.

    2005-12-01

    In many mapping applications of spatiotemporally distributed hydrological processes, the traditional space/time Geostatistics approaches have played a significant role to estimate a variable of interest at unsampled locations. Measured values are usually sparsely located over space and time due to the difficulty and cost of obtaining data. In some cases, the data for the hydrological variable of interest may have been collected at different temporal or spatial observation scales. Even though mixing data measured at different space/time scales may alleviate the problem of the sparsity of the data available, it essentially disregards the scale effect of estimation results. The importance of the scale effect must be recognized since a variable displays different physical properties depending on the spatial or temporal scale at which it is observed. In this study we develop a mathematical framework to derive the conditional Probability Density Function (PDF) of a variable at the local scale given an observation of that variable at a larger spatial or temporal scale, which properly models the uncertainty associated with the different observations scales of space/time natural processes. The developed framework allows to efficiently mix data observed at a variety of scales by accounting for data uncertainty associated with each observation scale present, and therefore generates soft data rigorously assimilated in the Bayesian Maximum Entropy (BME) method of modern Geostatistics to increase the mapping accuracy of the map at the scale of interest. We investigate the proposed approach with synthetic case studies involving observations of a space/time process at a variety of temporal and spatial scales. These case studies demonstrate the power of the proposed approach by leading to a set of maps with a noticeable increase of mapping accuracy over classical approaches not accounting for the scale effects. Hence the proposed approach will be useful for a wide variety of applications in hydrology and other earth sciences fields.

  9. Lower Triassic marine d34S trend in the Dolomites (Northern Italy)

    NASA Astrophysics Data System (ADS)

    Horacek, M.; Brandner, R.

    2009-04-01

    The Permian - Triassic boundary marks the severest mass extinction in earth history. More than 90 % of all skeleton building species became extinct in this event. Despite numerous investigations the responsible mechanisms still are not unequivocally identified. Among the more popular hypotheses are bolide impact, global warming, global cooling, global ocean water poisoning, marine anoxia and volcanism. To identify the processes that really were relevant during this unusual period geochemical proxies are investigated. Here we present some sulphur isotope data of evaporites from the Permian-Triassic Boundary and the Lower Triassic in the Dolomites (Northern Italy). The curve shows low values in the uppermost Permian and the basal Lower Triassic and increases steeply to significantly enriched values in the vicinity of the Dienerian-Spathian Boundary. The sulphur isotope values remain elevated for the Smithian and Spathian substages of the Lower Triassic. Changes in ocean circulation are the most plausible causes for the presented isotope curve.

  10. Triassic-Jurassic Mass Extinction: Evidence for Bolide Impact?

    NASA Astrophysics Data System (ADS)

    Perry, R.; Becker, L.; Haggart, J.; Poreda, R.

    2003-04-01

    The Triassic-Jurassic (TJ) mass extinction event is one of the most severe in geologic history and is one of the five largest in the Phanerozoic with as many as 80% of the species lost. It is also one of the most poorly understood. Only a few geologic sections have been identified for the TJ extinction and most of those are not well preserved. Previously, the paucity of suitable stratigraphic sections has prevented corroborative geochemical studies. Recently a well-preserved stratigraphic section spanning the Triassic-Jurassic boundary (˜200 mya) was identified at Kennecott Point, Queen Charlotte, Islands, British Columbia. Initial studies have shown that the Kennecott Point sequence is one of the best preserved and contains one of the most complete radiolarian microfossil turnovers known. Analyses of stable isotopes have shown that a 13C perturbation exits within the sequence and suggests a decline in organic productivity (Ward et al., 2001). Preliminary results of laser desorption mass spectrometry (LDMS) of selected Queen Charlotte samples suggest that fullerenes (C60 to C200) may be present in the Kennecott Point stratigraphic sequence. Previous studies have shown that fullerenes are present in the mass extinction boundary of the Permian-Triassic (˜251 mya) as well as the well-known "dinosaur" extinction event of the Cretaceous-Tertiary (˜65 mya). Therefore, three of the big five extinction events appear to have associated fullerenes. The possible presence of fullerenes along with the productivity collapse (rapid environmental change) suggests that a cometary or asteroidal impact may have occurred. Although no known impact crater exists, we hope to present chemical evidence that an impact or multiple impacts may have been responsible for the TJ mass extinction.

  11. Palaeomagnetic investigation on Early-Middle Triassic sediments of the North China block: a new Early Triassic palaeopole and its tectonic implications

    NASA Astrophysics Data System (ADS)

    Huang, Baochun; Shi, Ruiping; Wang, Yongcheng; Zhu, Rixiang

    2005-01-01

    Palaeomagnetic and rock magnetic study is reported of Early-Middle Triassic terrestrial sediments from the Jiaocheng and Yushe areas, Shanxi province. Thermomagnetic analysis indicates that magnetite and haematite are the main magnetic carriers. Thermal demagnetization shows that the majority of Early Triassic specimens from the Jiaocheng area contain an intermediate-temperature component (ITC) between 500 -250 °C and a high-temperature component (HTC) between 500-680 °C. The ITC has a negative fold test and might be a Cretaceous or recent overprint. The HTC contains both normal and reversed polarities with positive fold and C-level reversal tests. We interpret the HTC as primary magnetization. Unfortunately, we failed to isolate a meaningful mean direction from Middle Triassic rocks of the Yushe area. New Early Triassic palaeopole from the Jiaocheng area confirms an ~ 10° counter-clockwise displacement of the Taihang Early Triassic palaeopoles relative to their Ordos counterparts. This study thus suggests that the North China block (NCB) has generally behaved as rigid block since the Early Triassic, but there might be an ~9° counter-clockwise rotation of the Taihang terrane with respect to stable NCB in the Late Triassic. The slight rotation of the Taihang terrane does not bear significantly on what has been previously concluded concerning the Mesozoic history of the NCB-South China block (SCB) collision. However, Triassic palaeomagnetic data from stable NCB indicate that the east end of the NCB and SCB did not undergo large convergence or significant opposite latitudinal displacement after the initial contact at the end of the Late Permian.

  12. Quasi Periodic Oscillations (QPOs) in Blazars on Diverse Time Scales

    NASA Astrophysics Data System (ADS)

    Gupta, A. C.

    2010-12-01

    Blazars, including BL Lacertae objects (BL Lacs) and flat spectrum radio quasars (FSRQs), are subclass of radio-loud active galactic nuclei (AGN) with relativistic jets aligned nearly with the line of sight. Blazar emission extends across the entire electromagnetic (EM) spectrum and they show detectable flux variations on diverse timescales ranging from a few minutes through days and months to decades through all EM bands. The presence of quasi-periodic oscillations (QPOs) is fairly common in both black hole and neutron star binaries in our and nearby galaxies. Recently we have reported claims of QPOs detection on diverse timescales ranging from a few tens of minutes to hours to days and even months by using X-ray and optical time series data of blazars in a series of papers by my group. How to detect QPOs in time series data? What causes QPOs? What are likely the explanation of QPO detection in blazars? I will discuss these in my talk.

  13. Multi time-scale structure assignment for linear multivariable systems-Singular perturbation approach

    Microsoft Academic Search

    A. Saberi; P. Sannuti

    1986-01-01

    In this paper we examine the problem of high-gain output feedback for linear time-invariant multivariable systems. More specifically, we do the following: ¿ We study the possible set of multiple time-scale structures that can be assigned via high-gain output feedback control laws (We refer to this set as a set of 'achievable multiple time-scale structures'). ¿ We propose a design

  14. A robust two-time-scale control design for a pneumatic vibration isolator

    Microsoft Academic Search

    Dong Ki Han; Pyung Hun Chang

    2007-01-01

    Active pneumatic vibration isolators have been widely studied as the use of precision equipment increases. This paper focuses on the robust two-time-scale control design of an active pneumatic vibration isolator using the singular perturbation method and time delay control (TDC). The singular perturbation method, or more generally, the two-time-scale approach to feedback design is used to cope with the ill-conditioning

  15. Cycads from the Triassic of Antarctica: Permineralized Cycad Leaves

    E-print Network

    Hermsen, Elizabeth; Taylor, Thomas N.; Taylor, Edith L.; Stevenson, Dennis W.

    2007-09-01

    to extant genera (Pant 1987, 2002). While cuticular anatomy may provide diagnostic fea- tures (e.g., of stomata and epidermal cells), cuticle is lacking in many fossil leaves. Compounding the problem is the fact that leaves of some other groups...). An additional specimen was collected from Triassic Fremouw Formation strata at the base of Mount Falla, also in the Beardmore Glacier area (Barrett et al. 1986). Peat blocks were cut into sections, and the flat surfaces were polished and then etched in 48...

  16. Bi-Plasma Interactions on Femtosecond Time-Scales

    SciTech Connect

    Not Available

    2011-06-22

    Ultrafast THz radiation has important applications in materials science studies, such as characterizing transport properties, studying the vibrational response of materials, and in recent years, controlling materials and elucidating their response in intense electromagnetic fields. THz fields can be generated in a lab setting using various plasma-based techniques. This study seeks to examine the interaction of two plasmas in order to better understand the fundamental physics associated with femtosecond filamentation processes and to achieve more efficient THz generation in a lab setting. The intensity of fluorescence in the region of overlap was measured as a function of polarization, power, and relative time delay of the two plasma-generating laser beams. Results of time dependent intensity studies indicate strikingly similar behaviors across polarizations and power levels; a sudden intensity spike was observed at time-zero, followed by a secondary maxima and subsequent decay to the initial plasma intensity. Dependence of the intensity on the power through either beam arm was also observed. Spectral studies of the enhanced emission were also carried out. Although this physical phenomenon is still not fully understood, future studies, including further spectral analysis of the fluorescence overlap, could yield new insight into the ultrafast processes occurring at the intersection of femtosecond filaments, and would provide a better understanding of the mechanisms for enhanced THz production.

  17. Synchronous wildfire activity rise and mire deforestation at the triassic-jurassic boundary.

    PubMed

    Petersen, Henrik I; Lindström, Sofie

    2012-01-01

    The end-Triassic mass extinction event (?201.4 million years ago) caused major faunal and floral turnovers in both the marine and terrestrial realms. The biotic changes have been attributed to extreme greenhouse warming across the Triassic-Jurassic (T-J) boundary caused by massive release of carbon dioxide and/or methane related to extensive volcanism in the Central Atlantic Magmatic Province (CAMP), resulting in a more humid climate with increased storminess and lightning activity. Lightning strikes are considered the primary source of wildfires, producing charcoal, microscopically recognized as inertinite macerals. The presence of polycyclic aromatic hydrocarbons (PAHs) of pyrolytic origin and allochthonous charcoal in siliciclastic T-J boundary strata has suggested widespread wildfire activity at the time. We have investigated largely autochthonous coal and coaly beds across the T-J boundary in Sweden and Denmark. These beds consist of predominantly organic material from the in situ vegetation in the mires, and as the coaly beds represent a substantial period of time they are excellent environmental archives. We document a remarkable increase in inertinite content in the coal and coaly beds across the T-J boundary. We show estimated burning temperatures derived from inertinite reflectance measurements coupled with palynological data and conclude that pre-boundary late Rhaetian mire wildfires included high-temperature crown fires, whereas latest Rhaetian-Sinemurian mire wildfires were more frequent but dominated by lower temperature surface fires. Our results suggest a major change in the mire ecosystems across the T-J boundary from forested, conifer dominated mires to mires with a predominantly herbaceous and shrubby vegetation. Contrary to the overall regional vegetation for which onset of recovery commenced in the early Hettangian, the sensitive mire ecosystem remained affected during the Hettangian and did not start to recover until around the Hettangian-Sinemurian boundary. Decreasing inertinite content through the Lower Jurassic suggests that fire activity gradually resumed to considerable lower levels. PMID:23077574

  18. Synchronous Wildfire Activity Rise and Mire Deforestation at the Triassic–Jurassic Boundary

    PubMed Central

    Petersen, Henrik I.; Lindström, Sofie

    2012-01-01

    The end-Triassic mass extinction event (?201.4 million years ago) caused major faunal and floral turnovers in both the marine and terrestrial realms. The biotic changes have been attributed to extreme greenhouse warming across the Triassic–Jurassic (T–J) boundary caused by massive release of carbon dioxide and/or methane related to extensive volcanism in the Central Atlantic Magmatic Province (CAMP), resulting in a more humid climate with increased storminess and lightning activity. Lightning strikes are considered the primary source of wildfires, producing charcoal, microscopically recognized as inertinite macerals. The presence of polycyclic aromatic hydrocarbons (PAHs) of pyrolytic origin and allochthonous charcoal in siliciclastic T–J boundary strata has suggested widespread wildfire activity at the time. We have investigated largely autochthonous coal and coaly beds across the T–J boundary in Sweden and Denmark. These beds consist of predominantly organic material from the in situ vegetation in the mires, and as the coaly beds represent a substantial period of time they are excellent environmental archives. We document a remarkable increase in inertinite content in the coal and coaly beds across the T–J boundary. We show estimated burning temperatures derived from inertinite reflectance measurements coupled with palynological data and conclude that pre-boundary late Rhaetian mire wildfires included high-temperature crown fires, whereas latest Rhaetian–Sinemurian mire wildfires were more frequent but dominated by lower temperature surface fires. Our results suggest a major change in the mire ecosystems across the T–J boundary from forested, conifer dominated mires to mires with a predominantly herbaceous and shrubby vegetation. Contrary to the overall regional vegetation for which onset of recovery commenced in the early Hettangian, the sensitive mire ecosystem remained affected during the Hettangian and did not start to recover until around the Hettangian–Sinemurian boundary. Decreasing inertinite content through the Lower Jurassic suggests that fire activity gradually resumed to considerable lower levels. PMID:23077574

  19. Sodium storage in deep paleoweathering profiles beneath the Paleozoic-Triassic unconformity

    NASA Astrophysics Data System (ADS)

    Thiry, M.; Parcerisa, D.; Ricordel-Prognon, C.; Schmitt, J.-M.

    2009-04-01

    A major sodium accumulation has been recognized for long and by numerous authors in the Permo-Triassic salt deposits (Hay et al., 2006). Beside these basinal deposits, important masses of sodium were stored on the continents within deep palaeoweathering profiles in form of albite. Indeed, wide surfaces and huge volumes of granito-gneissic basements of the Hercynian massifs are albitized from North-Africa up to Scandinavia. These albitized rocks have usually been considered as related to tardi-magmatic metasomatic processes (Cathelineau 1986; Petersson and Eliasson 1997). Geometrical arrangement and dating of these alterations point out that these albitizations, or at least a part of them, developed under low temperature subsurface conditions in relation with the Triassic palaeosurface (Ricordel et al., 2007; Parcerisa et al., 2009). Petrology The albitized igneous rocks show a strong alteration with pseudomorphic replacement of the primary plagioclases into albite, replacement of primary biotite by chlorite and minor precipitation of neogenic minerals like albite, chlorite, apatite, haematite, calcite and titanite. Albitized rocks are characterized by their pink coloration due to the presence of minute haematite inclusions in the albite. The development and distribution of the albitization and related alterations above the unaltered basement occurs in three steps that define a vertical profile, up to 100-150 m depth. 1) In the lower part of the profile, albitization occurs within pink-colored patches in the unaltered rock, giving a pink-spotted aspect to the rock. 2) In the middle part of the profile, rocks have an overall pink coloration due to the albitization of the primary Ca-bearing igneous plagioclases. Usually, this facies develops in a pervasive manner, affecting the whole rock, but it may also be restricted to joints, giving a sharp-pink coloration to the fracture wall. 3) Finally, the top of the profile is defined by the same mineral paragenesis as in the pink stage, with an increase in the amount and size of sericite and hematite inclusions. The latter causes the red coloration of the altered rocks. Regional layout Regional distribution of the alterations which affect the Carboniferous igneous and volcanic formations beneath the Jurassic sedimentary cover lead to associate these alterations to the Triassic unconformity. Besides, albitized facies show generally both topographic and regional arrangements, with more altered facies occurring in the mountain highs and in the external parts of the massifs and unaltered facies occurring in the river valleys and in the central parts of the massifs. Moreover, the haematite associated with these albitized basement rocks has been dated from Early Trias by means of paleomagnetism (Ricordel et al, 2007). From this layout and dating, it is deduced that albitization is related to the development of a deep weathering profile (up to 150 m deep) during a long-lasting exposure of the Triassic erosional unconformity (regolith). Geochemistry and paleoenvironmental setting It has to be highlighted that, this alteration may not behave like an "ordinary" weathering profile and occurred under unusual, or at least very specific, geological settings. The scale of the profiles (over 100 m depth) relates this alteration rather to a groundwater environment. The weak mobility of most chemical elements may point to a groundwater with very low outflows and deep water table. This may occur in very subdued landscape and in arid climatic conditions. It has also to be pointed that this alteration may have lasted for several 10's of Ma. Albite formation at low temperature may be envisioned consequently in alkaline, confined waters with sufficient concentrations of sodium and silica. Early attempts of modeling (Schmitt, 1994) have also indicated that a high Na+/K+ ratio is as well probably required. Petrographic data also indicate an import of sodium by the weathering solutions, without any clear enrichment in potassium. The Na+ enrichment is most likely linked with the peculiar geochemic

  20. A multiscale mass scaling approach for explicit time integration using proper orthogonal decomposition

    SciTech Connect

    G. J. de Frias; W. Aquino; K. H. Pierson; M. W. Heinstein; B. W. Spencer

    2014-03-01

    One of the main computational issues with explicit dynamics simulations is the significant reduction of the critical time step as the spatial resolution of the finite element mesh increases. In this work, a selective mass scaling approach is presented that can significantly reduce the computational cost in explicit dynamic simulations, while maintaining accuracy. The proposed method is based on a multiscale decomposition approach that separates the dynamics of the system into low (coarse scales) and high frequencies (fine scales). Here, the critical time step is increased by selectively applying mass scaling on the fine scale component only. In problems where the response is dominated by the coarse (low frequency) scales, significant increases in the stable time step can be realized. In this work, we use the proper orthogonal decomposition (POD) method to build the coarse scale space. The main idea behind POD is to obtain an optimal low-dimensional orthogonal basis for representing an ensemble of high-dimensional data. In our proposed method, the POD space is generated with snapshots of the solution obtained from early times of the full-scale simulation. The example problems addressed in this work show significant improvements in computational time, without heavily compromising the accuracy of the results.

  1. Scaling Behavior of the First Arrival Time of a Random-Walking Magnetic Domain

    SciTech Connect

    Im, M.-Y.; Lee, S.-H.; Kim, D.-H.; Fischer, P.; Shin, S.-C.

    2008-02-04

    We report a universal scaling behavior of the first arrival time of a traveling magnetic domain wall into a finite space-time observation window of a magneto-optical microscope enabling direct visualization of a Barkhausen avalanche in real time. The first arrival time of the traveling magnetic domain wall exhibits a nontrivial fluctuation and its statistical distribution is described by universal power-law scaling with scaling exponents of 1.34 {+-} 0.07 for CoCr and CoCrPt films, despite their quite different domain evolution patterns. Numerical simulation of the first arrival time with an assumption that the magnetic domain wall traveled as a random walker well matches our experimentally observed scaling behavior, providing an experimental support for the random-walking model of traveling magnetic domain walls.

  2. Modeling geomagnetic storms on prompt and diffusive time scales

    NASA Astrophysics Data System (ADS)

    Li, Zhao

    The discovery of the Van Allen radiation belts in the 1958 was the first major discovery of the Space Age. There are two belts of energetic particles. The inner belt is very stable, but the outer belt is extremely variable, especially during geomagnetic storms. As the energetic particles are hazardous to spacecraft, understanding the source of these particles and their dynamic behavior driven by solar activity has great practical importance. In this thesis, the effects of magnetic storms on the evolution of the electron radiation belts, in particular the outer zone, is studied using two types of numerical simulation: radial diffusion and magnetohydrodynamics (MHD) test-particle simulation. A radial diffusion code has been developed at Dartmouth, applying satellite measurements to model flux as an outer boundary condition, exploring several options for the diffusion coefficient and electron loss time. Electron phase space density is analyzed for July 2004 coronal mass ejection (CME) driven storms and March-April 2008 co-rotating interaction region (CIR) driven storms, and compared with Global Positioning System (GPS) satellite measurements within 5 degrees of the magnetic equator at L=4.16. A case study of a month-long interval in the Van Allen Probes satellite era, March 2013, confirms that electron phase space density is well described by radial diffusion for the whole month at low first invariant <400~MeV/G, but peaks in phase space density observed by the ECT instrument suite at higher first invariant are not reproduced by radial transport from a source at higher L. A 3D guiding center code with plasmasheet injection is used to simulate particle motion in time-dependent MHD fields calculated from the Lyon-Fedder-Mobarry global MHD code, as an extension of the Hudson et al. (2012) study of the Whole Heliosphere Interval of CIR-driven storms in March-April 2008. Direct comparison with measured fluxes at GOES show improved comparison with observations relative to the 2D guiding center test particle simulations and enhancement of flux at >0.6 MeV by an order of magnitude over 24 hours as observed.

  3. A carapace-like bony 'body tube' in an early triassic marine reptile and the onset of marine tetrapod predation.

    PubMed

    Chen, Xiao-hong; Motani, Ryosuke; Cheng, Long; Jiang, Da-yong; Rieppel, Olivier

    2014-01-01

    Parahupehsuchus longus is a new species of marine reptile from the Lower Triassic of Yuan'an County, Hubei Province, China. It is unique among vertebrates for having a body wall that is completely surrounded by a bony tube, about 50 cm long and 6.5 cm deep, comprising overlapping ribs and gastralia. This tube and bony ossicles on the back are best interpreted as anti-predatory features, suggesting that there was predation pressure upon marine tetrapods in the Early Triassic. There is at least one sauropterygian that is sufficiently large to feed on Parahupehsuchus in the Nanzhang-Yuan'an fauna, together with six more species of potential prey marine reptiles with various degrees of body protection. Modern predators of marine tetrapods belong to the highest trophic levels in the marine ecosystem but such predators did not always exist through geologic time. The indication of marine-tetrapod feeding in the Nanzhang-Yuan'an fauna suggests that such a trophic level emerged for the first time in the Early Triassic. The recovery from the end-Permian extinction probably proceeded faster than traditionally thought for marine predators. Parahupehsuchus has superficially turtle-like features, namely expanded ribs without intercostal space, very short transverse processes, and a dorsal outgrowth from the neural spine. However, these features are structurally different from their turtle counterparts. Phylogeny suggests that they are convergent with the condition in turtles, which has a fundamentally different body plan that involves the folding of the body wall. Expanded ribs without intercostal space evolved at least twice and probably even more among reptiles. PMID:24718682

  4. A Carapace-Like Bony ‘Body Tube’ in an Early Triassic Marine Reptile and the Onset of Marine Tetrapod Predation

    PubMed Central

    Chen, Xiao-hong; Motani, Ryosuke; Cheng, Long; Jiang, Da-yong; Rieppel, Olivier

    2014-01-01

    Parahupehsuchus longus is a new species of marine reptile from the Lower Triassic of Yuan’an County, Hubei Province, China. It is unique among vertebrates for having a body wall that is completely surrounded by a bony tube, about 50 cm long and 6.5 cm deep, comprising overlapping ribs and gastralia. This tube and bony ossicles on the back are best interpreted as anti-predatory features, suggesting that there was predation pressure upon marine tetrapods in the Early Triassic. There is at least one sauropterygian that is sufficiently large to feed on Parahupehsuchus in the Nanzhang-Yuan’an fauna, together with six more species of potential prey marine reptiles with various degrees of body protection. Modern predators of marine tetrapods belong to the highest trophic levels in the marine ecosystem but such predators did not always exist through geologic time. The indication of marine-tetrapod feeding in the Nanzhang-Yuan’an fauna suggests that such a trophic level emerged for the first time in the Early Triassic. The recovery from the end-Permian extinction probably proceeded faster than traditionally thought for marine predators. Parahupehsuchus has superficially turtle-like features, namely expanded ribs without intercostal space, very short transverse processes, and a dorsal outgrowth from the neural spine. However, these features are structurally different from their turtle counterparts. Phylogeny suggests that they are convergent with the condition in turtles, which has a fundamentally different body plan that involves the folding of the body wall. Expanded ribs without intercostal space evolved at least twice and probably even more among reptiles. PMID:24718682

  5. Temperature analysis of laser heated polymers on microsecond time scales

    NASA Astrophysics Data System (ADS)

    Kappes, Ralf S.; Schönfeld, Friedhelm; Li, Chen; Gutmann, Jochen S.; Butt, Hans-Jürgen

    2012-03-01

    To investigate the temperature profiles on laser heated polymer films, we track the thermal radiation with 1 ?s time and 1 ?m spatial resolution. The resulting two-dimensional temperature graphs are compared to finite element simulations in order to understand the heat conversion and flow. The temperature measurement setup consists of a NIR laser and an optical detection system, which includes high performance optics and a microsecond gated camera, equipped with several interference filters. In this way the thermal radiation is detected in the visible range with spectral resolution. Fitting the spectrum with Planck's law, two-dimensional micrographs of the temperature distribution are obtained. For polystyrene surfaces we were able to analyze the heating and the ablation behavior. Good agreement was found between experimental results and finite element simulations, when ablation is limited to a few tens of nanometers of the film thickness. Ablation of polystyrene starts at 150°C, 50 K above the glass transition temperature. We suggest a photomechanical ablation mechanism at that threshold fluence. For ablation at higher fluence and peak temperature, experiments indicate a thermal decomposition reaction. The temperature range of spinodal decomposition is not reached and can in our case be ruled out as ablation mechanism.

  6. Updating the planetary time scale: focus on Mars

    USGS Publications Warehouse

    Tanaka, Kenneth L.; Quantin-Nataf, Cathy

    2013-01-01

    Formal stratigraphic systems have been developed for the surface materials of the Moon, Mars, Mercury, and the Galilean satellite Ganymede. These systems are based on geologic mapping, which establishes relative ages of surfaces delineated by superposition, morphology, impact crater densities, and other relations and features. Referent units selected from the mapping determine time-stratigraphic bases and/or representative materials characteristic of events and periods for definition of chronologic units. Absolute ages of these units in some cases can be estimated using crater size-frequency data. For the Moon, the chronologic units and cratering record are calibrated by radiometric ages measured from samples collected from the lunar surface. Model ages for other cratered planetary surfaces are constructed primarily by estimating cratering rates relative to that of the Moon. Other cratered bodies with estimated surface ages include Venus and the Galilean satellites of Jupiter. New global geologic mapping and crater dating studies of Mars are resulting in more accurate and detailed reconstructions of its geologic history.

  7. Short time-scale periodicity in OJ 287

    NASA Astrophysics Data System (ADS)

    Pihajoki, P.; Valtonen, M.; Ciprini, S.

    2013-10-01

    We have studied short-term variations of the blazar OJ 287, suspected to host a supermassive black hole binary. In this study, we use a two-season optical R-band data set from 2004 to 2006 which consists of 3991 data points from the OJ 287 observation campaign. It has sections of dense time coverage, and is largely independent from previously published data. We find that these data confirm the existence of a ˜50 d periodic component, presumably related to the half-period of the innermost stable circular orbit (ISCO) of the primary black hole. In addition, we find several pseudo-periodic components in the 1-7 d range, most prominently at 3.5 d, which are likely Lorentz contracted jet re-emission of the 50 d component. The typical 50-d cycle exhibits a slow rise of brightness and a rapid dimming before the start of the new cycle. We explain this as being due to a spiral wave in the accretion disc which feeds the central black hole in this manner.

  8. ago (Australia) and even 4 million years ago (Hawaii)--the sorts of time scales studied

    E-print Network

    Bristol, University of

    485 ago (Australia) and even 4 million years ago (Hawaii)--the sorts of time scales studied-for-time substitution to the study of ecosystem dynamics requires that assump- tions be made, for example, that external renewable, P is not and is leached from soils over time, leading to a phosphorus-depeleted ecosystem

  9. The osteology of the basal archosauromorph Tasmaniosaurus triassicus from the Lower Triassic of Tasmania, Australia.

    PubMed

    Ezcurra, Martín D

    2014-01-01

    Proterosuchidae are the most taxonomically diverse archosauromorph reptiles sampled in the immediate aftermath of the Permo-Triassic mass extinction and represent the earliest radiation of Archosauriformes (archosaurs and closely related species). Proterosuchids are potentially represented by approximately 15 nominal species collected from South Africa, China, Russia, Australia and India, but the taxonomic content of the group is currently in a state of flux because of the poor anatomic and systematic information available for several of its putative members. Here, the putative proterosuchid Tasmaniosaurus triassicus from the Lower Triassic of Hobart, Tasmania (Australia), is redescribed. The holotype and currently only known specimen includes cranial and postcranial remains and the revision of this material sheds new light on the anatomy of the animal, including new data on the cranial endocast. Several bones are re-identified or reinterpreted, contrasting with the descriptions of previous authors. The new information provided here shows that Tasmaniosaurus closely resembles the South African proterosuchid Proterosuchus, but it differed in the presence of, for example, a slightly downturned premaxilla, a shorter anterior process of maxilla, and a diamond-shaped anterior end of interclavicle. Previous claims for the presence of gut contents in the holotype of Tasmaniosaurus are considered ambiguous. The description of the cranial endocast of Tasmaniosaurus provides for the first time information about the anatomy of this region in proterosuchids. The cranial endocast preserves possibly part of the vomero-nasal (?=?Jacobson's) system laterally to the olfactory bulbs. Previous claims of the absence of the vomero-nasal organs in archosaurs, which is suggested by the extant phylogenetic bracket, are questioned because its absence in both clades of extant archosaurs seems to be directly related with the independent acquisition of a non-ground living mode of life. PMID:24497988

  10. Time scales of porphyry Cu deposit formation: insights from titanium diffusion in quartz

    USGS Publications Warehouse

    Mercer, Celestine N.; Reed, Mark H.; Mercer, Cameron M.

    2015-01-01

    Porphyry dikes and hydrothermal veins from the porphyry Cu-Mo deposit at Butte, Montana, contain multiple generations of quartz that are distinct in scanning electron microscope-cathodoluminescence (SEM-CL) images and in Ti concentrations. A comparison of microprobe trace element profiles and maps to SEM-CL images shows that the concentration of Ti in quartz correlates positively with CL brightness but Al, K, and Fe do not. After calibrating CL brightness in relation to Ti concentration, we use the brightness gradient between different quartz generations as a proxy for Ti gradients that we model to determine time scales of quartz formation and cooling. Model results indicate that time scales of porphyry magma residence are ~1,000s of years and time scales from porphyry quartz phenocryst rim formation to porphyry dike injection and cooling are ~10s of years. Time scales for the formation and cooling of various generations of hydrothermal vein quartz range from 10s to 10,000s of years. These time scales are considerably shorter than the ~0.6 m.y. overall time frame for each porphyry-style mineralization pulse determined from isotopic studies at Butte, Montana. Simple heat conduction models provide a temporal reference point to compare chemical diffusion time scales, and we find that they support short dike and vein formation time scales. We interpret these relatively short time scales to indicate that the Butte porphyry deposit formed by short-lived episodes of hydrofracturing, dike injection, and vein formation, each with discrete thermal pulses, which repeated over the ~3 m.y. generation of the deposit.

  11. RAP: A Real-Time Communication Architecture for Large-Scale Wireless Sensor Networks

    E-print Network

    Stankovic, John A.

    .g., PDA's). Because distributed micro-sensing involves direct in- teraction with a physical environmentRAP: A Real-Time Communication Architecture for Large-Scale Wireless Sensor Networks Chenyang Lu of Virginia Charlottesville, VA 22903 {chenyang, bmb5v, zaher, stankovic, th7c}@cs.virginia.edu Abstract Large-scale

  12. What response times tell of childrens behavior on the balance scale task

    Microsoft Academic Search

    Brenda R. J. Jansen

    Analysis of accuracy of responses to balance scale problems gives a global idea of the cog- nitive processes that underlie problem-solving behavior on this task. We show that response times (RTs) provide additional detailed information about the kind and duration of these pro- cesses. We derive predictions about the RTs from Sieglers (1981) model for the balance scale task, including

  13. Picosecond Time-Resolved Strain Rosette at Atomic Length Scale

    NASA Astrophysics Data System (ADS)

    Campana, Maria I.; Williams, G. Jackson; Heyong Lee, Soo; Walko, Donald; Landahl, Eric

    2013-03-01

    Ultrafast optical absorption in a crystalline solid generates coherent motions of strain, which propagate through the bulk at the speed of sound. Energy relaxation dynamics of the excited lattice system and the subsequent transport properties of the strains have been actively studied. Recently, these high-speed transient dynamics have been studied using laser based pump-probe techniques and time resolved x-ray diffraction (TRXD). However, the interpretation of these studies always assumes a uniaxial spatial profile for the strain (i.e. strain is exerted only along the direction of surface normal of the sample). This assumption comes from a symmetry argument originally given by Thomsen: if the illuminated area of the pump laser beam on the sample surface is much larger than the optical penetration depth, strain gradient along surface normal is expected to be much steeper than along lateral direction, and therefore, the strain generated is usually assumed to be one dimensional. While this assumption simplifies the analysis of the data, (and makes possible such applications as picosecond ultrasonics for the in-situ measurement of semiconductor heterostructure thickness), it overlooks any physical processes that take place along transverse direction. Here we report the experimental generation and detection of the transverse component of the impulsively generated strain in a single GaAs crystal using TRXD. Our analysis is based on a strain rosette applied to three non-collinear Bragg reflections. Ultrafast optical absorption in a crystalline solid generates coherent motions of strain, which propagate through the bulk at the speed of sound. Energy relaxation dynamics of the excited lattice system and the subsequent transport properties of the strains have been actively studied. Recently, these high-speed transient dynamics have been studied using laser based pump-probe techniques and time resolved x-ray diffraction (TRXD). However, the interpretation of these studies always assumes a uniaxial spatial profile for the strain (i.e. strain is exerted only along the direction of surface normal of the sample). This assumption comes from a symmetry argument originally given by Thomsen: if the illuminated area of the pump laser beam on the sample surface is much larger than the optical penetration depth, strain gradient along surface normal is expected to be much steeper than along lateral direction, and therefore, the strain generated is usually assumed to be one dimensional. While this assumption simplifies the analysis of the data, (and makes possible such applications as picosecond ultrasonics for the in-situ measurement of semiconductor heterostructure thickness), it overlooks any physical processes that take place along transverse direction. Here we report the experimental generation and detection of the transverse component of the impulsively generated strain in a single GaAs crystal using TRXD. Our analysis is based on a strain rosette applied to three non-collinear Bragg reflections. Present affiliation: University of California, Davis

  14. Variability Trends in QSOs Over Monthly Time Scales

    NASA Astrophysics Data System (ADS)

    Fleming, B. T.; Kennefick, J.

    2005-12-01

    Variation in quasar magnitude from night to night can reveal long term variability trends as well as have a greater chance of detecting sudden luminosity changes than a typical long-term variability survey. In this study, five quasars with a range of properties were observed approximately every other night over 40 days using the 24" NFO webscope in Silver City, NM. Three 200 second exposure images were taken in both the R and V color filters each observation. Two passbands were used so that the data could be correlated to support findings. The images were stacked and processed using IRAF and SExtractor. Differential photometry using field stars was utilized. The five quasars were selected so that as large a range of redshift and absolute magnitude observable by the NFO webscope was represented. They are: (1) MRK 0877 with z=0.1124, (2) 3C-334 a RQQ with z=0.5551, (3) HS 1603+3820 a very luminous, very distant QSO with z=2.51, and two quasars from the QUEST survey (J1507-0202 and J1507-0207) which were selected because they both showed evidence of magnitude variations during the QUEST1 survey. Two of the observed quasars showed no significant variability. 3C-334 displayed a sudden apparent magnitude jump in both passbands, with ? mR = 0.5602 ± 0.0474, corresponding to an increase of 6.62E+11 solar luminosities on June 21st. The magnitude returned to previous levels by the next observation. QUEST 1507-0202 and MRK 0877 suggested evidence of small long term variability over the 40 day study. Future observations revealing significant changes in magnitude corresponding to these trends may lead to the conclusion that these slow long-term variations can be detected over a 40 day time period with frequent observations. Funding was provided through an Arkansas Space Center grant.

  15. Existence of Solutions for a One Dimensional p-Laplacian on Time-Scales

    E-print Network

    Anderson, Douglas R.

    real numbers), or hZ (a constant graininess), the p-Laplacian arises in non-Newtonian fluids, in some theorem of Calculus, a result that has been generalized and extended to time-scales; to gain a good

  16. Scaling turbulent atmospheric stratification, Part III: Space-time stratification of passive scalars from lidar data

    E-print Network

    Long, Bernard

    Scaling Analysis Technique (ASAT) which is based on a nonlinear space- time coordinate transformation discussed in part II. Using the ASAT technique we verified the theory to within about 10% over more than 3

  17. Minimal variability time scale - central black hole mass relation of the ?-ray loud blazars

    NASA Astrophysics Data System (ADS)

    Vovk, Ievgen; Babi?, Ana

    2015-06-01

    Context. The variability time scales of the blazar ?-ray emission contain the imprints of the sizes of their emission zones and are generally expected to be larger than the light-crossing times of these zones. In several cases the time scales were found to be as short ~ 10 min, suggesting that the emission zone sizes are comparable with the sizes of the central supermassive black holes. Previously, these measurements also led to the suggestion of a possible connection between the observed minimal variability time scales and the masses of the corresponding black holes. This connection can be used to determine the location of the ?-ray emission site, which currently remains uncertain. Aims: The study aims to investigate the suggested "minimum time scale - black hole mass" relation using the blazars, detected in the TeV band. Methods: To obtain the tightest constraints on the variability time scales this work uses a compilation of observations by the Cherenkov telescopes HESS, MAGIC, and VERITAS. These measurements are compared to the blazar central black hole masses found in the literature. Results: The majority of the studied blazars show the variability time scales which are at least comparable to the period of rotation along the last stable orbit of the central black hole - and in some cases as short as its light-crossing time. For several sources the observed variability time scales are found to be smaller than the black hole light-crossing time. This suggests that the detected ?-ray variability originates, most probably, from the turbulence in the jet, sufficiently far from the central black hole.

  18. Paleomagnetic Constraints on the Permian-Triassic Boundary in Terrestrial Strata of the Karoo Supergroup, South Africa: Implications for Causes of the End-Permian Extinction Event

    Microsoft Academic Search

    M. O. De Kock; J. L. Kirschvink

    The closure of the Palaeozoic witnessed the greatest biotic crisis in earth history. Surprisingly little is known about the effects and timing of the terrestrial counterpart of the well-described End-Permian mass extinction from known marine successions worldwide. In the present study, reliable paleomagnetic results were obtained from a PT boundary section in the terrestrial Karoo Basin of South Africa. Permo-Triassic

  19. Simulations of mass-transport processes on short observation time scales in nonideal dissipative systems

    Microsoft Academic Search

    O. S. Vaulina; O. F. Petrov; V. E. Fortov

    2005-01-01

    We present the results of our numerical simulations of mass-transport processes on short observation time scales for extended\\u000a quasi-two-dimensional and three-dimensional nonideal dissipative systems of macroparticles interacting through a screened\\u000a Coulomb potential. The simulations were performed for the parameters corresponding to the experimental conditions in laboratory\\u000a dusty plasmas. The evolution of the rms macroparticle displacement on short observation time scales

  20. Parallel design of suboptimal regulators for singularly perturbed systems with multiple-time scales

    Microsoft Academic Search

    Yue-Yun Wang; Paul M. Frank

    1991-01-01

    The problem for near optimal control of linear systems with multiple-time-scale singular perturbations is studied by a descriptor variable approach. The near optimum regulator problem with multiple-time-scale singular perturbations is decomposed into a number of N+1 subregulator problems. The solutions are mutually independent, and are standard solutions of Riccati equations without parasitic parameters. The algorithm for parallel solutions of these

  1. Multiple time-scales in nonlinear flight mechanics: diagnosis and modeling

    Microsoft Academic Search

    K. D. Mease

    2005-01-01

    There are often disparate time-scales in the dynamics of flight, creating the potential for reduced-order modeling to simplify simulation, analysis and design. There have been notable successes in developing reduced-order models; however, in the case of nonlinear dynamics, which one must typically deal with in guidance problems, there has not been a systematic, reliable means of diagnosing disparate time-scales and

  2. Differences in Spatial Patterns of Drought on Different Time Scales: An Analysis of the Iberian Peninsula

    Microsoft Academic Search

    Sergio M. Vicente-Serrano

    2006-01-01

    The differences in spatial patterns of drought over a range of time scales were analysed by the Standardized Precipitation\\u000a Index (SPI). In a climatic area with a wide range of precipitation characteristics (the Iberian Peninsula), Pearson III distribution\\u000a is flexible enough to calculate the drought index on different time scales. The Pearson III distribution was adapted to precipitation\\u000a frequencies at

  3. Local scale invariance, Cantorian space–time and unified field theory

    Microsoft Academic Search

    Ervin Goldfain

    2005-01-01

    We develop field theoretic arguments for the unification of relativistic gravity with standard model interactions on El Naschie's Cantorian space–time. The work proceeds by showing the equivalence between the fundamental principle of local gauge invariance and the local scale invariance of space–time and matter fields undergoing critical behavior on high-energy scales. We focus on the transition boundary between the classical

  4. Disentangling the Hettangian carbon isotope record: Implications for the aftermath of the end-Triassic mass extinction

    NASA Astrophysics Data System (ADS)

    Bartolini, A.; Guex, J.; Spangenberg, J. E.; Schoene, B.; Taylor, D. G.; Schaltegger, U.; Atudorei, V.

    2012-01-01

    This study provides an organic carbon stable isotope (?13Corg) record calibrated with detailed ammonite biostratigraphy, following the end-Triassic biological crisis. Precise correlation between this crucial fossil group and the ?13Corg record is key to understanding feedbacks between biological and environmental events following mass extinction. The latest Triassic and Hettangian ?13Corg record shows several negative and positive excursions. The end-Triassic negative shift coinciding with the mass extinction interval is followed by a positive excursion in the earliest Hettangian Psiloceras spelae beds, which marks the onset of recovery in the marine ecosystem. This positive trend is interrupted by a second negative ?13Corg excursion in the P. pacificum beds related to a minor ammonite extinction event. This pattern of the ?13Corg curve culminates in the uppermost Hettangian Angulata Zone major positive excursion. This indicates that both the ecosystem and the carbon cycle remained in a state of perturbation for at least 2 Ma, although the recovery of some pelagic taxa already began at the base of Jurassic. The early and late Hettangian positive ?13Corg excursions have been confused in several recent papers. Here, we show that during the Hettangian there are indeed two distinct positive ?13Corg excursions. Phases of anoxia and further pulses of Central Atlantic Magmatic Province volcanism during the Hettangian might have inhibited the full recovery for that interval of time. The main Liasicus-Angulata organic positive CIE (carbon isotope excursion) during the Late Hettangian might be related to gradual decreasing of pCO2 due to protracted high organic burial, and coincides with a second phase of recovery, as indicated by a pulse of ammonoid diversification.

  5. A hybrid procedure for MSW generation forecasting at multiple time scales in Xiamen City, China

    SciTech Connect

    Xu, Lilai, E-mail: llxu@iue.ac.cn [Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021 (China); Xiamen Key Lab of Urban Metabolism, Xiamen 361021 (China); Gao, Peiqing, E-mail: peiqing15@yahoo.com.cn [Xiamen City Appearance and Environmental Sanitation Management Office, 51 Hexiangxi Road, Xiamen 361004 (China); Cui, Shenghui, E-mail: shcui@iue.ac.cn [Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021 (China); Xiamen Key Lab of Urban Metabolism, Xiamen 361021 (China); Liu, Chun, E-mail: xmhwlc@yahoo.com.cn [Xiamen City Appearance and Environmental Sanitation Management Office, 51 Hexiangxi Road, Xiamen 361004 (China)

    2013-06-15

    Highlights: ? We propose a hybrid model that combines seasonal SARIMA model and grey system theory. ? The model is robust at multiple time scales with the anticipated accuracy. ? At month-scale, the SARIMA model shows good representation for monthly MSW generation. ? At medium-term time scale, grey relational analysis could yield the MSW generation. ? At long-term time scale, GM (1, 1) provides a basic scenario of MSW generation. - Abstract: Accurate forecasting of municipal solid waste (MSW) generation is crucial and fundamental for the planning, operation and optimization of any MSW management system. Comprehensive information on waste generation for month-scale, medium-term and long-term time scales is especially needed, considering the necessity of MSW management upgrade facing many developing countries. Several existing models are available but of little use in forecasting MSW generation at multiple time scales. The goal of this study is to propose a hybrid model that combines the seasonal autoregressive integrated moving average (SARIMA) model and grey system theory to forecast MSW generation at multiple time scales without needing to consider other variables such as demographics and socioeconomic factors. To demonstrate its applicability, a case study of Xiamen City, China was performed. Results show that the model is robust enough to fit and forecast seasonal and annual dynamics of MSW generation at month-scale, medium- and long-term time scales with the desired accuracy. In the month-scale, MSW generation in Xiamen City will peak at 132.2 thousand tonnes in July 2015 – 1.5 times the volume in July 2010. In the medium term, annual MSW generation will increase to 1518.1 thousand tonnes by 2015 at an average growth rate of 10%. In the long term, a large volume of MSW will be output annually and will increase to 2486.3 thousand tonnes by 2020 – 2.5 times the value for 2010. The hybrid model proposed in this paper can enable decision makers to develop integrated policies and measures for waste management over the long term.

  6. Comparison of transient stability analysis and large-scale real time digital simulation

    Microsoft Academic Search

    Paul Forsyth; Rick Kuffel; Rudi Wierckx; Jin-Boo Choo; Yong-Beum Yoon; Tae-Kyun Kim

    2001-01-01

    The KEPS Real Time Digital Simulator (RTDS(R)) is the largest real time power system simulator ever built. A power system which includes 320 (3-phase) buses and 90 generators has been modeled and run in real time. Since such large-scale systems were involved, it was not practical to validate them using nonreal time electromagnetic transient programs such as EMTDCTM or EMTP.

  7. C 1-Almost Periodic Solutions of BAM Neural Networks with Time-Varying Delays on Time Scales

    PubMed Central

    Li, Yongkun; Zhao, Lili; Yang, Li

    2015-01-01

    On a new type of almost periodic time scales, a class of BAM neural networks is considered. By employing a fixed point theorem and differential inequality techniques, some sufficient conditions ensuring the existence and global exponential stability of C 1-almost periodic solutions for this class of networks with time-varying delays are established. Two examples are given to show the effectiveness of the proposed method and results. PMID:25685847

  8. Towards a verifiable real-time, autonomic, fault mitigation framework for large scale real-time systems

    Microsoft Academic Search

    Abhishek Dubey; Steven Nordstrom; Turker Keskinpala; Sandeep Neema; Ted Bapty; Gabor Karsai

    2007-01-01

    Designing autonomic fault responses is difficult, particularly in large-scale systems, as there is no single ‘perfect’ fault\\u000a mitigation response to a given failure. The design of appropriate mitigation actions depend upon the goals and state of the\\u000a application and environment. Strict time deadlines in real-time systems further exacerbate this problem. Any autonomic behavior\\u000a in such systems must not only be

  9. Carboniferous-Triassic subduction and accretion in the western Kunlun, China: Implications for the collisional and accretionary tectonics of the northern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Jiao Xiao, Wen; Windley, Brian F.; Chen, Han Lin; Zhang, Guo Cheng; Li, Ji Liang

    2002-04-01

    A newly defined, 250 km by 500 km, Carboniferous-Triassic subduction-accretion complex, the Mazar accretionary prism in the western Kunlun, comprises two subduction complexes and a forearc-basin succession. (1) The Bazar Dara subduction complex contains imbricated blocks of sandstone, arenite, limestone, and metavolcanic rocks in a matrix of weakly metamorphosed Triassic deep-sea turbidites. The metavolcanic rocks include basalt, diabase, spilite, and andesitic porphyry. Trace element geochemistry shows that pillow and amygdaloidal basalts are oceanic-island tholeiites. This zone has Ordovician to Permian fossils and is situated on the older, more highly deformed and metamorphosed side of the prism adjacent to the Sailiyak magmatic arc. (2) The Heweitan subduction complex is composed of blocks of limestone, turbidite, and radiolarite in a slate-phyllite matrix intercalated with calc-alkalic volcanic rocks. This complex has Permian to Triassic fossils and is situated on the younger, less deformed, and metamorphosed side of the prism adjacent to the suture zone. (3) The Qitai forearc basins are infilled with turbidites (Late Triassic) intercalated with carbonates; these rocks overlie the accretionary prism. The accretion-related structure is dominated by large-scale northeast-dipping thrusts and subvertical cleavage stitched by 215 190 Ma granites. There is an overall decrease in metamorphic grade and deformation intensity from the arc to the suture zone across the Bazar Dara and Heweitan subduction complexes. The Mazar accretionary prism formed by subduction-accretion processes during closure of the Paleotethyan Ocean and the final docking of the Gondwanan Karakoram-Qiangtang block to the Cathaysian (Eurasian) Kunlun block.

  10. Validating a rapid-update satellite precipitation analysis across telescoping space and time scales

    NASA Astrophysics Data System (ADS)

    Turk, Francis Joseph; Sohn, Byung-Ju; Oh, Hyun-Jong; Ebert, Elizabeth E.; Levizzani, Vincenzo; Smith, Eric A.

    2009-09-01

    In order to properly utilize remotely sensed precipitation estimates in hydrometeorological applications, knowledge of the accuracy of the estimates are needed. However, relatively few ground validation networks operate with the necessary spatial density and time-resolution required for validation of high-resolution precipitation products (HRPP) generated at fine space and time scales (e.g., hourly accumulations produced on a 0.25° spatial scale). In this article, we examine over-land validation statistics for an operationally designed, meteorological satellite-based global rainfall analysis that blends intermittent passive microwave-derived rainfall estimates aboard a variety of low Earth-orbiting satellite platforms with sub-hourly time sampling capabilities of visible and infrared imagers aboard operational geostationary platforms. The validation dataset is comprised of raingauge data collected from the dense, nearly homogeneous, 1-min reporting Automated Weather Station (network of the Korean Meteorological Administration during the June to August 2000 summer monsoon season. The space-time RMS error, mean bias, and correlation matrices were computed using various time windows for the gauge averaging, centered about the satellite observation time. For ±10 min time window, a correlation of 0.6 was achieved at 0.1° spatial scale by averaging more than 3 days; coarsening the spatial scale to 1.8° produced the same correlation by averaging over 1 h. Finer than approximately 24-h and 1° time and space scales, respectively, a rapid decay of the error statistics was obtained by trading-off either spatial or time resolution. Beyond a daily time scale, the blended estimates were nearly unbiased and with an RMS error of no worse than 1 mm day-1.

  11. A Dynamic Voltage Scaling Algorithm for Dynamic-Priority Hard Real-Time Systems Using Slack Time Analysis

    Microsoft Academic Search

    Woonseok Kim; Jihong Kim; Sang Lyul Min

    2002-01-01

    Dynamic voltage scaling (DVS), which adjusts the clockspeed and supply voltage dynamically, is an effective techniquein reducing the energy consumption of embedded real-timesystems. The energy efficiency of a DVS algorithm largelydepends on the performance of the slack estimation methodused in it. In this paper, we propose a novel DVS algorithmfor periodic hard real-time tasks based on an improved slackestimation algorithm.

  12. Multi-physics investigation on the failure mechanism and short-time scale wave motion in flip-chip configuration 

    E-print Network

    Oh, Yoonchan

    2005-11-01

    thermal stresses and improving solder joint fatigue performance in thermal cycling tests of long-time scale, underfill material viscoelasticity was found to be insignificant in attenuating short-time scale wave propagation. On the other hand...

  13. Time operators in stroboscopic wave-packet basis and the time scales in tunneling

    SciTech Connect

    Bokes, P. [Department of Physics, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, SK-812 19 Bratislava (Slovakia) and ETSF, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom)

    2011-03-15

    We demonstrate that the time operator that measures the time of arrival of a quantum particle into a chosen state can be defined as a self-adjoint quantum-mechanical operator using periodic boundary conditions and applied to wave functions in energy representation. The time becomes quantized into discrete eigenvalues; and the eigenstates of the time operator, i.e., the stroboscopic wave packets introduced recently [Phys. Rev. Lett. 101, 046402 (2008)], form an orthogonal system of states. The formalism provides simple physical interpretation of the time-measurement process and direct construction of normalized, positive definite probability distribution for the quantized values of the arrival time. The average value of the time is equal to the phase time but in general depends on the choice of zero time eigenstate, whereas the uncertainty of the average is related to the traversal time and is independent of this choice. The general formalism is applied to a particle tunneling through a resonant tunneling barrier in one dimension.

  14. Lower Jurassic unconformity (J-O) from the Colorado Plateau to the eastern Mojave Desert: evidence of a major tectonic event at the close of the Triassic

    SciTech Connect

    Marzolf, J.E. (Southern Illinois Univ., Carbondale (USA))

    1991-04-01

    From southern Nevada to the eastern Mojave Desert, the Lower Jurassic basal unconformity (J-0) cuts down section from the Upper Triassic Chinle Formation to deformed Paleozoic carbonate rocks. The Chinle Formation is not present southwest of the central Spring Mountians. Stratigraphic relations suggest correlation of J-0 with unconformities in western Arizona and the Inyo Mountains. Close proximity of J-0 in time and space to (1) first appearance of western-derived volcanic clasts in lower Mesozoic cratonal stratigraphy, (2) early Mesozoic thrust faults, and (3) the J-1 cusp in the apparent polar wander path imply a major change in tetonic setting of the southwestern Cordillera at the Triassic/Jurassic boundary.

  15. Detrital zircon U-Pb geochronology of Cambrian to Triassic miogeoclinal and eugeoclinal strata of Sonora, Mexico

    USGS Publications Warehouse

    Gehrels, G.E.; Stewart, John H.

    1998-01-01

    One hundred and eighty two individual detrital zircon grains from Cambrian through Permian miogeoclinal strata, Ordovician eugeoclinal rocks, and Triassic post-orogenic sediments in northwestern Sonora have been analyzed. During Cambrian, Devonian, Permian, and Triassic time, most zircons accumulating along this part of the Cordilleran margin were shed from 1.40-1.45 and 1.62-1.78 Ga igneous rocks that are widespread in the southwestern United States and northwestern Mexico. Zircons with ages of approximately 1.11 Ga are common in Cambrian strata and were apparently shed from granite bodies near the sample site. The sources of 225-280 Ma zircons in our Triassic sample are more problematic, as few igneous rocks of these ages are recognized in northwestern Mexico. Such sources may be present but unrecognized, or the grains could have been derived from igneous rocks of the appropriate ages to the northwest in the Mojave Desert region, to the east in Chihuahua and Coahuila, or to the south in accreted(?) arc-type terranes. Because the zircon grains in our Cambrian and Devonian to Triassic samples could have accumulated in proximity to basement rocks near their present position or in the Death Valley region of southern California, our data do not support or refute the existence of the Mojave-Sonora megashear. Ordovician strata of both miogeoclinal and eugeoclinal affinity are dominated by >1.77 Ga detrital zircons, which are considerably older than most basement rocks in the region. Zircon grains in the miogeoclinal sample were apparently derived from the Peace River arch area of northwestern Canada and transported southward by longshore currents. The eugeoclinal grains may also have come from the Peace River arch region, with southward transport by either sedimentary or tectonic processes, or they may have been shed from off-shelf slivers of continents (perhaps Antarctica?) removed from the Cordilleran margin during Neoproterozoic rifting. It is also possible that the Ordovician eugeoclinal strata are far traveled and exotic to North America.

  16. COLLABORATION OF REAL TIME GIS AND SPATIAL DATA FOR LARGE SCALE MAP

    Microsoft Academic Search

    Aki OKUNO; Sota SHIMANO; Masaaki SHIKADA

    Much local government has been using large scale digital maps with Geographic Information System (GIS). However, the updating method of a map is not established yet. The purpose of this study is the real-time renewal of the digital map for local government by collaboration of REAR TIME GIS and spatial data. In this study, spatial data means Remote Sensing imageries

  17. The Effect of Multiple Time Scales and Subexponentiality in MPEG Video Streams on Queueing Behavior

    Microsoft Academic Search

    Predrag R. Jelenkovic; Aurel A. Lazar; Nemo Semret

    1997-01-01

    Guided by the empirical observation that real- time MPEG video streams exhibit both multiple time scale and subexponential characteristics, we construct a video model that captures both of these characteristics and is amenable to queueing analysis. We investigate two fundamental approaches for extract- ing the model parameters: using sample path and second-order statistics-based methods. The model exhibits the following two

  18. Real-time 3-D object recognition using Scale Invariant Feature Transform and stereo vision

    Microsoft Academic Search

    Gee-Sern Hsu; Chyi-Yeu Lin; Jia-Shan Wu

    2009-01-01

    Scale invariant feature transform (SIFT) and stereo vision are applied together to recognize objects in real time. This work reports the performance of a GPU (graphic processing unit) based real-time feature detector in capturing the features of 3D objects when the objects undergo rotational and translational motions in cluttered backgrounds. We have compared the performance of the feature detector implemented

  19. A multi-time scale non-Gaussian model of stock returns

    Microsoft Academic Search

    Lisa Borland

    2004-01-01

    We propose a stochastic process for stock movements that, with just one source of Brownian noise, has an instantaneous volatility that rises from a type of statistical feedback across many time scales. This results in a stationary non-Gaussian process which captures many features observed in time series of real stock returns. These include volatility clustering, a kurtosis which decreases slowly

  20. Fast Similarity Search in the Presence of Noise, Scaling, and Translation in Time-Series Databases

    Microsoft Academic Search

    Rakesh Agrawal; King-ip Lin; Harpreet S. Sawhney; Kyuseok Shim

    1995-01-01

    We introduce a new model of similarity of time se- quences that captures the intuitive notion that two sequences should be considered similar if they have enough non-overlapping time-ordered pairs of subse- quences thar are similar. The model allows the am- plitude of one of the two sequences to be scaled by any suitable amount and its offset adjusted appropriately.

  1. Disk File Management in a Medium-Scale Time-Sharing System.

    ERIC Educational Resources Information Center

    Fitzhugh, Robert J.; Pethia, Richard D.

    The paper descibes a compact and highly efficient disk file management system responsible for the management and allocation of space on moving head disk drives in a medium-scale time-sharing system. The disk file management system is a major component of the Experimental Time-Sharing System (ETSS) developed at the Learning Research and Development…

  2. Characteristic Time Scales of Transport Processes for Chemotactic Bacteria in Groundwater: Analysis of Pore-scale to Field-scale Experimental Data

    NASA Astrophysics Data System (ADS)

    Ford, R. M.

    2010-12-01

    Many processes contribute to the transport of microorganisms in groundwater environments. One process of interest is chemotaxis, whereby motile bacteria are able to detect and swim toward increasing concentrations of industrial hydrocarbons that they perceive as food sources. By enabling bacteria to migrate to the sources of pollutants that they degrade, chemotaxis has the potential to enhance bioremediation efforts, especially in less permeable zones where contamination may persist. To determine the field conditions under which chemotaxis might be exploited in a bioremediation scheme requires an understanding of the characteristic time scales in the system. We defined a dimensionless chemotaxis number that compares the time over which a bacterial population is exposed to a chemical gradient to the time required for a bacterial population to migrate a significant distance in response to a chemical gradient. The exposure time and the response time are dependent upon the experimental conditions and properties of the bacteria and chemical attractant. Experimental data was analyzed for a range of groundwater flow rates over a wide scope of experimental systems including a single-pore with NAPL source, a microfluidic channel with and without a porous matrix, a laboratory column, a bench-scale microcosm and a field-scale study. Chemical gradients were created transverse to the flow direction. Distributions of chemotactic and nonchemotactic bacteria were compared to determine the extent of migration due to chemotaxis. Under some conditions at higher flow rates, the effect of chemotaxis was diminished to the point of not being detected. The goal of the study was to determine a critical value for the dimensionless chemotaxis number (which is independent of scale) that can be used as a design criterion to ascertain a priori the conditions under which a chemotactic response will impact bacterial transport relative to other processes such as advection and dispersion.

  3. Coevolution of strategy-selection time scale and cooperation in spatial prisoner's dilemma game

    NASA Astrophysics Data System (ADS)

    Rong, Zhihai; Wu, Zhi-Xi; Chen, Guanrong

    2013-06-01

    In this paper, we investigate a networked prisoner's dilemma game where individuals' strategy-selection time scale evolves based on their historical learning information. We show that the more times the current strategy of an individual is learnt by his neighbors, the longer time he will stick on the successful behavior by adaptively adjusting the lifetime of the adopted strategy. Through characterizing the extent of success of the individuals with normalized payoffs, we show that properly using the learned information can form a positive feedback mechanism between cooperative behavior and its lifetime, which can boost cooperation on square lattices and scale-free networks.

  4. Can inertial electrostatic confinement work beyond the ion--ion collisional time scale?

    SciTech Connect

    Nevins, W.M. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    1995-10-01

    Inertial electrostatic confinement (IEC) systems are predicated on a nonequilibrium ion distribution function. Coulomb collisions between ions cause this distribution to relax to a Maxwellian on the ion--ion collisional time scale. The power required to prevent this relaxation and maintain the IEC configuration for times beyond the ion--ion collisional time scale is shown to be greater than the fusion power produced. It is concluded that IEC systems show little promise as a basis for the development of commercial electric power plants. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  5. Can inertial electrostatic confinement work beyond the ion-ion collisional time scale?

    SciTech Connect

    Nevins, W.M.

    1995-01-01

    Inertial electrostatic confinement systems are predicated on a non-equilibrium ion distribution function. Coulomb collisions between ions cause this distribution to relax to a Maxwellian on the ion-ion collisional time-scale. The power required to prevent this relaxation and maintain the IEC configuration for times beyond the ion-ion collisional time scale is shown to be at least an order of magnitude greater than the fusion power produced. It is concluded that IEC systems show little promise as a basis for the development of commercial electric power plants.

  6. Acoustic Emission Monitoring of the Syracuse Athena Temple: Scale Invariance in the Timing of Ruptures

    SciTech Connect

    Niccolini, G.; Carpinteri, A.; Lacidogna, G.; Manuello, A. [Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino (Italy)] [Department of Structural Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

    2011-03-11

    We perform a comparative statistical analysis between the acoustic-emission time series from the ancient Greek Athena temple in Syracuse and the sequence of nearby earthquakes. We find an apparent association between acoustic-emission bursts and the earthquake occurrence. The waiting-time distributions for acoustic-emission and earthquake time series are described by a unique scaling law indicating self-similarity over a wide range of magnitude scales. This evidence suggests a correlation between the aging process of the temple and the local seismic activity.

  7. Experiments on a time scale algorithm for introducing hydrogen masers into an ensemble of caesium clocks

    NASA Astrophysics Data System (ADS)

    Zhengming, Wang

    2008-12-01

    The frequency characteristics of two hydrogen masers at the National Time Service Center are studied in this paper by comparing the Allan deviation with the Hadamard deviation. The results show that the hydrogen masers exhibit a linear frequency drift (Lfd) within a period of about a few tens of days. The main purpose here is to test whether such hydrogen masers could contribute to a time scale composed of a clock ensemble and how to deal with the algorithm. It proves feasible and effective to remove the Lfds from the phase data of the masers according to the frequency prediction before data are added to the time scale computation.

  8. A particle-resolved modeling approach for estimating black carbon aging time-scales

    NASA Astrophysics Data System (ADS)

    Riemer, N. S.; West, M.; Zaveri, R. A.; Easter, R. C.; Fierce, L. M.; Bond, T. C.

    2012-12-01

    The composition of carbonaceous aerosol particles changes continuously after emission during their transport in the atmosphere. Coagulation and condensation are contributing processes, collectively known as aging. This changes the particles' physico-chemical properties, in particular their hygroscopicity, from initially hydrophobic to more hydrophilic, and hence their ability to act as cloud condensation nuclei. In many global models the aging process is modeled as a first-order system with the single parameter of aging rate or its inverse, the aging time-scale. Sensitivity studies have shown that the black carbon burden in global models depends strongly on the assumed aging time-scale, hence constraining this value is important for predicting the black carbon climate impacts. Here we will present a method for explicitly calculating aging time-scales of black carbon aerosol using the particle-resolved model PartMC-MOSAIC. We used the activation of the particles at a given supersaturation as a criterion for aging, and consider condensation of semivolatile species and coagulation as aging mechanisms. We then developed a library of approximately 300 scenarios to explore the sensitivity of this aging time-scale to a range of environmental parameters and pollution characteristics. From this ensemble of simulations the following results emerge: The aging time-scale is heavily dependent on the chosen supersaturation threshold. Decreasing this threshold from 0.6% to 0.1% increases the aging time-scale by a factor of 20 (median). The nitrate-dominated simulations, which have the highest rates of gas-to-particle conversion, lead to the lowest aging time-scales, with day-time averages on the order of 1 hour for the 0.6% supersaturation threshold. This value depends in turn on temperature and relative humidity as they govern nitrate formation. Daytime aging time-scales are about a factor of 5 smaller than the corresponding nighttime aging time-scales when the 0.6% supersaturation threshold is used. This day-night difference decreases for smaller supersaturation thresholds. We are also able to quantify the extent to which aging is due to condensation versus coagulation processes. Both of them play important roles in aging, and their relative impact depends on the particle size range.

  9. Oceanographic Changes through the Early Triassic Crisis Interval

    NASA Astrophysics Data System (ADS)

    Algeo, T. J.

    2013-12-01

    Recent studies of diverse paleoceanographic proxies have provided the basis for reconstructing in some detail oceanographic changes during the end-Permian mass extinction and through the ~5-million-year-long Early Triassic crisis interval. Conodont ?18O records have demonstrated strong warming, to tropical sea-surface temperatures as high as 40oC, during the Griesbachian to Dienerian substages1-2. The crisis interval also was associated with major perturbations in the marine carbon and sulfur cycles. Three episodes of strong warming coincided with decreases in marine carbonate ?13C and marine sulfate ?34S 3, as well as increases in ??13Cvert4 and enhanced subaerial weathering fluxes5-6. Lower ?13Ccarb and ?34Ssulf values are indicative of more limited burial of reduced C and S in organic carbon and pyrite, consistent with declines in marine productivity and bacterial sulfate reduction3. Increased ??13Cvert is indicative of intensified stratification of the oceanic water column4, and increased subaerial weathering fluxes probably reflect higher soil reaction rates and possibly an intensified hydrologic cycle5-6. Collectively, these patterns are indicative of the globally integrated response of marine and terrestrial regimes to episodic perturbations in the form of extreme warming events1-2,7. These warming events may have been triggered by major volcanic eruptions8, as suggested by recent studies of volcanic ash layers9-10 and rare earth elements11 in South China P-Tr boundary sections. The ~2-million-year-long Early Triassic interval of extreme sea-surface temperatures came to an abrupt end around the Smithian-Spathian boundary1-2. Cooling coincided with a sharp decline in ??13Cvert due to stronger vertical overturning circulation4 and a major positive excursion in ?13Ccarb due to increased marine productivity related to greater mixing of nutrients into the ocean-surface layer12. The late Spathian was characterized by a final, weaker episode of sea-surface warming and attendant effects prior to the cessation of external perturbations to the marine system around the Early/Middle Triassic boundary. These oceanographic changes conform closely to the pattern and tempo of marine ecosystem recovery during the Early Triassic13. 1Sun, Y., et al., 2012, Science 338:366-370. 2Romano, C., et al., 2013, Nature Geosci. 6:57-60. 3Luo, G.M., et al., 2010, Earth Planet. Sci. Lett. 300:101-111. 4Song, H.Y., et al., 2013, Global Planet. Change 105:7-20. 5Algeo, T.J., Twitchett, R.J., 2010, Geology 38:1023-1026. 6Algeo, T.J., et al., 2011, Palaeogeogr. Palaeoclimatol. Palaeoecol. 308:1-11. 7Yin, H.F., et al., 2012, Earth-Sci. Rev. 115:163-172. 8Xie, S.C., et al., 2010, Geology 38:447-450. 9Shen, J., et al., 2012, Geology 40:963-966. 10Shen, J., et al., 2012, Geobiology 10:82-103. 11Zhao, L., et al., 2013, Global Planet. Change 105:135-151. 12Tong, J.N., et al., 2007, Geol. Jour. 42:371-389. 13Chen, Z.Q., Benton, M.J., 2012, Nature Geosci. 5:375-383.

  10. Permo-Triassic Events in the Eastern Tethys

    NASA Astrophysics Data System (ADS)

    Sweet, Walter C.; Zunyi, Yang; Dickins, J. M.; Hongfu, Yin

    2003-12-01

    Permian and Triassic rocks in the eastern Tethyan region form continuous marine sequences that record the waning phases of the Paleozoic and the early stages of the Mesozoic eras. This book describes and interprets these rocks, summarizing the distribution of major fossil groups in a way that will allow detailed comparison with strata of comparable age in the western Tethys and other parts of the world. The sixteen contributions by forty authors are the culmination of the five-year long International Geological Correlation Programme Project 203. The detailed information presented here is gathered from many areas in the eastern Tethyan region - from France to Australia - and will be of use in the evaluation of the major changes in the global marine biosphere known to have taken place at the end of the Paleozoic era. The stratigraphic record for this fascinating segment of Earth history is not widespread elsewhere in the world and is most continuous in the region covered by this book.

  11. Nothosaur foraging tracks from the Middle Triassic of southwestern China.

    PubMed

    Zhang, Qiyue; Wen, Wen; Hu, Shixue; Benton, Michael J; Zhou, Changyong; Xie, Tao; Lü, Tao; Huang, Jinyuan; Choo, Brian; Chen, Zhong-Qiang; Liu, Jun; Zhang, Qican

    2014-01-01

    The seas of the Mesozoic (266-66 Myr ago) were remarkable for predatory marine reptiles, but their modes of locomotion have been debated. One problem has been the absence of tracks, although there is no reason to expect that swimmers would produce tracks. We report here seabed tracks made by Mesozoic marine reptiles, produced by the paddles of nothosaurs (Reptilia, Sauropterygia) in the Middle Triassic of the Luoping localities in Yunnan, southwestern China. These show that the track-making nothosaurs used their forelimbs for propulsion, they generally rowed (both forelimbs operating in unison rather than alternately), and the forelimb entered medially, dug in as the paddle tip gained purchase, and withdrew cleanly. These inferences may provide evidence for swimming modes, or it could be argued that the locomotory modes indicated by the tracks were restricted to such contact propulsion. Such punting behaviour may have been used to flush prey from the bottom muds. PMID:24917514

  12. How East Asian Monsoon responds to solar forcing at multiple time scales during the Holocene with EMD method

    Microsoft Academic Search

    Liu Hy; Lin Zs

    2010-01-01

    The forcing of variability in East Asian Monsoon (EAM) at millennial- to decadal-scale is always on debates. In this paper, we will decomposed the ´ 18O (East Asian Monsoon record) and 14C (solar activities record) time series into variations at different time scales with EMD method to reveal how EAM responds to the solar forcing at different time scales. The

  13. Detailed Gravity and Magnetic Survey of the Taylorsville Triassic Basin

    SciTech Connect

    Ali A. Nowroozi; John Leftwich

    1997-12-31

    Our research to date has involved the Interpretation of the Bouguer Gravity Anomaly Associated with the Richmond and Taylorsville Triassic Basins and its Vicinity. Continental rift basins around the world contain about 5% of the earth's sedimentary layers and produce about 20% of the total hydrocarbon production of the world (Ziegler (1983). Nearly 30 large basins of this type are reported by Manspeizer and Cousminer (1988) in eastern North America and northwestern Africa. There are eleven exposed basins of this type in the state of Virginia, from which nine are totally and two partially within the state's border. The number of unexposed basin's is not known. Exploration and drilling have been hampered largely because surface data are insufficient for even evaluation of those basins which are partly or completely exposed in the Piedmont Province. Generation of data through random exploratory drilling and seismic exploration is much too expensive and, therefore, these methods have not been widely used. In order to remedy this situation, we have used a geophysical method and completed a detailed and dense ground gravity surveys of the Richmond (Nowroozi and Wong, 1989, Daniels and Nowroozi, 1987). In this work we report our progress on collecting existing gravity data in a rectangular area covering the Richmond and Taylorsville Basins and its vicinity. The area covers one degree latitude and one degree longitude, starting at 37 North, 77 West and ending at 38 North, 78 West. Dr. David Daniels of the United State Geological Survey supplied us with more than 4900 Bouguer gravity anomalies in this area. The purpose of this progress report is to present the data in form of several maps and discuss its relation to the geology of the Triassic Basins and its vicinity. Johnson and others (1985) also presented a map of the Bouguer gravity anomaly of this area. However, their map covers a smaller area, and it is based on smaller number of observations.

  14. Continental Ecosystem Instability During the Late Triassic Rise of Dinosaurs

    NASA Astrophysics Data System (ADS)

    Whiteside, J. H.; Dunlavey, M.; Lindström, S.; Irmis, R. B.; Kasprak, A. H.; Glasspool, I.; Nesbitt, S.; Smith, N.; Turner, A.

    2012-12-01

    Our assessment of the Earth system response to future global climate change requires the characterization of feedbacks that occur at temperatures significantly warmer than modern. Patterns derived from hothouse intervals in Earth's past can inform process-based models to better understand and predict such feedbacks. pCO2 values exceeded 1000 ppm during the Late Triassic (~235 million to 201.5 million years ago), one of the warmest - and one of the most climatically dynamic - intervals in Earth history. This long period of warmth saw rare and species-poor assemblages of early dinosaurs and their relatives at low-paleolatitudes. Here we present new records of palynology, charcoal, polycyclic aromatic hydrocarbon (PAH) biomarkers of regional wildfires, and the bulk carbon isotopic composition of organic matter (?13Corg) from fluvial and overbank sediments of the Chinle Formation of the Chama Basin in north-central New Mexico from low paleolatitude Pangea. These data illuminate the climatic and ecological drivers of low dinosaur diversity. Our data suggest that strongly fluctuating but generally very hot and periodically arid environmental conditions prevailed at low paleolatitudes in the Late Triassic. Strong variations in ?13Corg and xerophytic palynomorph abundance are highly correlated, suggesting these proxies responded to fluctuating arid conditions with intermittent wildfires, some burning at temperatures reaching at least 680°C. The abundant, reliable food source required by an extensive, diverse community of large-bodied, herbivorous, fast-growing tachymetabolic dinosaurs did not develop until climatic changes in the Early Jurassic. Despite this, the basic structure of this pseudosuchian archosaur-dominated community remained stable over ~10-15 million years.

  15. Jurassic and triassic hydrocarbon exploration of southern Florida

    SciTech Connect

    Mitchell-Tapping, H.J. [Retog, Inc., DeSoto, TX (United States)

    1994-12-31

    The Triassic and Jurassic of South Florida have been overlooked as a viable exploration target because of lack of data and plate tectonics application. In Florida {open_quotes}basement{close_quotes} is defined as crystalline, igneous, metamorphic and unmetamorphosed sediments of Paleozoic age. Age-dating of zircons has shown that the Florida lower Paleozoic terrain is not akin to that of North America but is part of the West African Guinean Shield. Pre-Atlantic reconstruction of the Gulf of Mexico in this study suggests that there was a Florida connection to Yucatan-Cuba-Africa during the Triassic. This reconstruction also shows that Jurassic rocks that are well known in the Northern Gulf Coast should have been deposited in similar depositional environments in southern Florida. Deep drilling on the Florida peninsula has confirmed this hypothesis. By using plate tectonic reconstruction based on the rifting of the North Atlantic Ocean and evidence from petrology of basement samples from deep wells, together with petrographic analyses of Jurassic sedimentary rocks, a Smackover-equivalent exploration play can be developed. Petrographic and petrophysical analysis of wells that have encountered Jurassic marine shales, anhydrite, dolomite, carbonate, and clastic sedimentary rocks has determined that they were deposited in shallow-water subtidal to supratidal environments. Excellent gas shows, oil stain in pores, and high TOC values in marine shales indicate that there are accumulations of hydrocarbon present. Application of analogous Gulf Coast Smackover stratigraphic models to this area, based on petrology and hydrogeology, should reduce risk and help define productive oil and gas reservoirs.

  16. Triassic Vertebrates of Gondwanan Aspect from the Richmond Basin of Virginia

    E-print Network

    Olsen, Paul E.

    Triassic Vertebrates of Gondwanan Aspect from the Richmond Basin of Virginia A new localityof early,SYNAPSID- dominated assemblages of terres- trial vertebrates, persisting from the late Paleozoic, gave way

  17. Resetting the evolution of marine reptiles at the Triassic-Jurassic boundary

    PubMed Central

    Thorne, Philippa M.; Ruta, Marcello; Benton, Michael J.

    2011-01-01

    Ichthyosaurs were important marine predators in the Early Jurassic, and an abundant and diverse component of Mesozoic marine ecosystems. Despite their ecological importance, however, the Early Jurassic species represent a reduced remnant of their former significance in the Triassic. Ichthyosaurs passed through an evolutionary bottleneck at, or close to, the Triassic-Jurassic boundary, which reduced their diversity to as few as three or four lineages. Diversity bounced back to some extent in the aftermath of the end-Triassic mass extinction, but disparity remained at less than one-tenth of pre-extinction levels, and never recovered. The group remained at low diversity and disparity for its final 100 Myr. The end-Triassic mass extinction had a previously unsuspected profound effect in resetting the evolution of apex marine predators of the Mesozoic. PMID:21536898

  18. Field Guide to the Vertebrate Paleontology of Late Triassic Age Rocks in the Southwestern

    E-print Network

    Olsen, Paul E.

    Field Guide to the Vertebrate Paleontology of Late Triassic Age Rocks in the Southwestern Newark Meeting of the Society of Vertebrate Paleontology, in Philadelphia. This paper is essentially an updated

  19. Moist Static Energy Budget Analysis on Various Time-scales during TOGA COARE

    NASA Astrophysics Data System (ADS)

    Inoue, K.; Back, L. E.

    2014-12-01

    Temperature variability is small in the tropics, so anomalous moist static energy (MSE) is primarily due to anomalous moisture variability which is tightly connected with precipitation variability. Thus careful analysis of MSE budgets improves our understanding of the dynamics of tropical convection. Previous studies suggested that a recharge-discharge cycle of column-integrated MSE can be observed in the MJO life-cycle and life-cycles of equatorial Kelvin waves. Does this imply that the thermodynamics in the MJO is regulated by a similar process to that of higher frequency variability? To answer this question, we explore the recharge and discharge mechanisms of column-integrated MSE for various time-scales of variability using the TOGA COARE data set. We find that the MSE budgets behave in significantly different ways on the different time-scales. The relative contribution of each MSE budget term to the recharge-discharge mechanism gradually changes as the time-scale gets longer, making the MSE budget behavior on the MJO time-scale distinct from that on the shorter time-scales. For each frequency, we estimate the gross moist stability (GMS), which represents efficiency of MSE export via convection and associated large-scale circulations. The GMS has been used in many MJO studies. One of the popular usages is a linearization of vertical MSE advection in simplified MJO models with an assumption that the GMS is constant. In our analysis, we find that as the time-scale gets longer, the GMS, which is generally a highly variable quantity in a convective life-cycle, becomes a more constant quantity. We show that this more-constant GMS is primarily due to different patterns of the evolution of the vertical velocity profile.

  20. Modeling multiple time scale firing rate adaptation in a neural network of local field potentials.

    PubMed

    Lundstrom, Brian Nils

    2015-02-01

    In response to stimulus changes, the firing rates of many neurons adapt, such that stimulus change is emphasized. Previous work has emphasized that rate adaptation can span a wide range of time scales and produce time scale invariant power law adaptation. However, neuronal rate adaptation is typically modeled using single time scale dynamics, and constructing a conductance-based model with arbitrary adaptation dynamics is nontrivial. Here, a modeling approach is developed in which firing rate adaptation, or spike frequency adaptation, can be understood as a filtering of slow stimulus statistics. Adaptation dynamics are modeled by a stimulus filter, and quantified by measuring the phase leads of the firing rate in response to varying input frequencies. Arbitrary adaptation dynamics are approximated by a set of weighted exponentials with parameters obtained by fitting to a desired filter. With this approach it is straightforward to assess the effect of multiple time scale adaptation dynamics on neural networks. To demonstrate this, single time scale and power law adaptation were added to a network model of local field potentials. Rate adaptation enhanced the slow oscillations of the network and flattened the output power spectrum, dampening intrinsic network frequencies. Thus, rate adaptation may play an important role in network dynamics. PMID:25319064

  1. Space and time scales of shoreline change at Cape Cod National Seashore, MA, USA

    USGS Publications Warehouse

    Allen, J.R.; LaBash, C.L.; List, J.H.

    1999-01-01

    Different processes cause patterns of shoreline change which are exhibited at different magnitudes and nested into different spatial and time scale hierarchies. The 77-km outer beach at Cape Cod National Seashore offers one of the few U.S. federally owned portions of beach to study shoreline change within the full range of sediment source and sink relationships, and barely affected by human intervention. 'Mean trends' of shoreline changes are best observed at long time scales but contain much spatial variation thus many sites are not equal in response. Long-term, earlier-noted trends are confirmed but the added quantification and resolution improves greatly the understanding of appropriate spatial and time scales of those processes driving bluff retreat and barrier island changes in both north and south depocenters. Shorter timescales allow for comparison of trends and uncertainty in shoreline change at local scales but are dependent upon some measure of storm intensity and seasonal frequency. Single-event shoreline survey results for one storm at daily intervals after the erosional phase suggest a recovery time for the system of six days, identifies three sites with abnormally large change, and that responses at these sites are spatially coherent for now unknown reasons. Areas near inlets are the most variable at all time scales. Hierarchies in both process and form are suggested.

  2. Time-scales of close-in exoplanet radio emission variability

    NASA Astrophysics Data System (ADS)

    See, V.; Jardine, M.; Fares, R.; Donati, J.-F.; Moutou, C.

    2015-07-01

    We investigate the variability of exoplanetary radio emission using stellar magnetic maps and 3D field extrapolation techniques. We use a sample of hot Jupiter hosting stars, focusing on the HD 179949, HD 189733 and ? Boo systems. Our results indicate two time-scales over which radio emission variability may occur at magnetized hot Jupiters. The first is the synodic period of the star-planet system. The origin of variability on this time-scale is the relative motion between the planet and the interplanetary plasma that is corotating with the host star. The second time-scale is the length of the magnetic cycle. Variability on this time-scale is caused by evolution of the stellar field. At these systems, the magnitude of planetary radio emission is anticorrelated with the angular separation between the subplanetary point and the nearest magnetic pole. For the special case of ? Boo b, whose orbital period is tidally locked to the rotation period of its host star, variability only occurs on the time-scale of the magnetic cycle. The lack of radio variability on the synodic period at ? Boo b is not predicted by previous radio emission models, which do not account for the co-rotation of the interplanetary plasma at small distances from the star.

  3. Fossil Plants and Global Warming at the Triassic-Jurassic Boundary.

    PubMed

    McElwain; Beerling; Woodward

    1999-08-27

    The Triassic-Jurassic boundary marks a major faunal mass extinction, but records of accompanying environmental changes are limited. Paleobotanical evidence indicates a fourfold increase in atmospheric carbon dioxide concentration and suggests an associated 3 degrees to 4 degrees C "greenhouse" warming across the boundary. These environmental conditions are calculated to have raised leaf temperatures above a highly conserved lethal limit, perhaps contributing to the >95 percent species-level turnover of Triassic-Jurassic megaflora. PMID:10464094

  4. The Delayed Resurgence of Equatorial Forests after the Permian-Triassic Ecologic Crisis

    Microsoft Academic Search

    C. V. Looy; W. A. Brugman; D. L. Dilcher; H. Visscher

    1999-01-01

    In conjunction with the Permian-Triassic ecologic crisis ? 250 million years ago, massive dieback of coniferous vegetation resulted in a degradation of terrestrial ecosystems in Europe. A 4- to 5-million-year period of lycopsid dominance followed, and renewed proliferation of conifers did not occur before the transition between Early and Middle Triassic. We document this delayed re-establishment of equatorial forests on

  5. Ascent of Dinosaurs Linked to an Iridium Anomaly at the Triassic-Jurassic Boundary

    Microsoft Academic Search

    P. E. Olsen; D. V. Kent; H.-D. Sues; C. Koeberl; A. Montanari; E. C. Rainforth; S. J. Fowell; M. J. Szajna; B. W. Hartline

    2002-01-01

    Analysis of tetrapod footprints and skeletal material from more than 70 localities in eastern North America shows that large theropod dinosaurs appeared less than 10,000 years after the Triassic-Jurassic boundary and less than 30,000 years after the last Triassic taxa, synchronous with a terrestrial mass extinction. This extraordinary turnover is associated with an iridium anomaly (up to 285 parts per

  6. Late Early Triassic climate change: Insights from carbonate carbon isotopes, sedimentary evolution and ammonoid paleobiogeography

    Microsoft Academic Search

    Thomas Galfetti; Hugo Bucher; Arnaud Brayard; Peter A. Hochuli; Helmut Weissert; Kuang Guodun; Viorel Atudorei; Jean Guex

    2007-01-01

    The late Early Triassic sedimentary–facies evolution and carbonate carbon-isotope marine record (?13Ccarb) of ammonoid-rich, outer platform settings show striking similarities between the South China Block (SCB) and the widely distant Northern Indian Margin (NIM). The studied sections are located within the Triassic Tethys Himalayan belt (Losar section, Himachal Pradesh, India) and the Nanpanjiang Basin in the South China Block (Jinya

  7. Tectonic implications of early-middle Triassic palaeomagnetic results from Hexi Corridor, North China

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Yang, Zhenyu; Tong, Yabo; Yuan, Wei; Wang, Bin

    2010-09-01

    A palaeomagnetic study was carried out on low-middle Triassic red beds at Jingtai area of Hexi Corridor. The characteristic higher temperature component (HTC) (Ds = 304.1°, Is = 38.4°, ks = 33.2, a95 = 5.2°, N = 24 sites) isolated by stepwise thermal demagnetization exhibits dual polarity, which passes the McFadden's fold test at the 99 per cent confidence level and reversal test with classification C. Compared with coeval palaeomagnetic results from the North China Block (NCB), this result suggests insignificant palaeolatitude differences (P?) between the observed and that expected at Jingtai area (P? = -0.9° +/- 4.9° in the early Triassic or P? = 4.9° +/- 4.1° in the middle Triassic). This implies that the Hexi Corridor was the extension of the NCB by the middle Triassic. However, in comparison with early- and middle-Triassic results from the NCB, an anticlockwise rotation of studied area relative to the NCB with Rd = 25.4° +/- 5.2° or Rd = 26.6° +/- 4.5° is detected. Our result also suggests that Jingtai area of the western part of NCB was not connected with the Tarim block by the early-middle Triassic.

  8. Early archosauromorph remains from the Permo-Triassic Buena Vista Formation of north-eastern Uruguay.

    PubMed

    Ezcurra, Martín D; Velozo, Pablo; Meneghel, Melitta; Piñeiro, Graciela

    2015-01-01

    The Permo-Triassic archosauromorph record is crucial to understand the impact of the Permo-Triassic mass extinction on the early evolution of the group and its subsequent dominance in Mesozoic terrestrial ecosystems. However, the Permo-Triassic archosauromorph record is still very poor in most continents and hampers the identification of global macroevolutionary patterns. Here we describe cranial and postcranial bones from the Permo-Triassic Buena Vista Formation of northeastern Uruguay that contribute to increase the meagre early archosauromorph record from South America. A basioccipital fused to both partial exoccipitals and three cervical vertebrae are assigned to Archosauromorpha based on apomorphies or a unique combination of characters. The archosauromorph remains of the Buena Vista Formation probably represent a multi-taxonomic assemblage composed of non-archosauriform archosauromorphs and a 'proterosuchid-grade' animal. This assemblage does not contribute in the discussion of a Late Permian or Early Triassic age for the Buena Vista Formation, but reinforces the broad palaeobiogeographic distribution of 'proterosuchid grade' diapsids in Permo-Triassic beds worldwide. PMID:25737816

  9. Signal duration and the time scale dependence of signal integration in biochemical pathways

    E-print Network

    Jason W. Locasale

    2008-02-19

    Signal duration (e.g. the time scales over which an active signaling intermediate persists) is a key regulator of biological decisions in myriad contexts such as cell growth, proliferation, and developmental lineage commitments. Accompanying differences in signal duration are numerous downstream biological processes that require multiple steps of biochemical regulation. Here, we present an analysis that investigates how simple biochemical motifs that involve multiple stages of regulation can be constructed to differentially process signals that persist at different time scales. We compute the dynamic gain within these networks and resulting power spectra to better understand how biochemical networks can integrate signals at different time scales. We identify topological features of these networks that allow for different frequency dependent signal processing properties. Our studies suggest design principles for why signal duration in connection with multiple steps of downstream regulation is a ubiquitous control motif in biochemical systems.

  10. New time scale based k-epsilon model for near-wall turbulence

    NASA Technical Reports Server (NTRS)

    Yang, Z.; Shih, T. H.

    1993-01-01

    A k-epsilon model is proposed for wall bonded turbulent flows. In this model, the eddy viscosity is characterized by a turbulent velocity scale and a turbulent time scale. The time scale is bounded from below by the Kolmogorov time scale. The dissipation equation is reformulated using this time scale and no singularity exists at the wall. The damping function used in the eddy viscosity is chosen to be a function of R(sub y) = (k(sup 1/2)y)/v instead of y(+). Hence, the model could be used for flows with separation. The model constants used are the same as in the high Reynolds number standard k-epsilon model. Thus, the proposed model will be also suitable for flows far from the wall. Turbulent channel flows at different Reynolds numbers and turbulent boundary layer flows with and without pressure gradient are calculated. Results show that the model predictions are in good agreement with direct numerical simulation and experimental data.

  11. A new time scale based k-epsilon model for near wall turbulence

    NASA Technical Reports Server (NTRS)

    Yang, Z.; Shih, T. H.

    1992-01-01

    A k-epsilon model is proposed for wall bonded turbulent flows. In this model, the eddy viscosity is characterized by a turbulent velocity scale and a turbulent time scale. The time scale is bounded from below by the Kolmogorov time scale. The dissipation equation is reformulated using this time scale and no singularity exists at the wall. The damping function used in the eddy viscosity is chosen to be a function of R(sub y) = (k(sup 1/2)y)/v instead of y(+). Hence, the model could be used for flows with separation. The model constants used are the same as in the high Reynolds number standard k-epsilon model. Thus, the proposed model will be also suitable for flows far from the wall. Turbulent channel flows at different Reynolds numbers and turbulent boundary layer flows with and without pressure gradient are calculated. Results show that the model predictions are in good agreement with direct numerical simulation and experimental data.

  12. Evidence for the Permo-Triassic transtensional rifting in the Iberian Range (NE Spain) according to magnetic fabrics results

    NASA Astrophysics Data System (ADS)

    García-Lasanta, C.; Oliva-Urcia, B.; Román-Berdiel, T.; Casas, A. M.; Gil-Peña, I.; Sánchez-Moya, Y.; Sopeña, A.; Hirt, A. M.; Mattei, M.

    2015-05-01

    Anisotropy of magnetic susceptibility (AMS) techniques are applied to Permo-Triassic red beds from the Castilian Branch (Iberian Range, NE Spain) that were deposited in an extensional basin inverted during Cenozoic times. The main goal of this work is to characterize the tectonic evolution of the basinal stage by differentiating synsedimentary to early diagenetic magnetic fabrics from the secondary tectonic fabrics related to compression, which are scarcely developed because no penetrative structures related to compression have been recognized. Oblate magnetic fabrics, with kmin axes perpendicular to bedding ,are observed in most cases. Magnetic lineations are variable, showing a dominant ENE-WSW maximum, which fits with a dextral transtensional regime acting on NW-SE master faults during the Triassic. We propose that variations in the orientation of the magnetic lineation are associated with transfer faults which fragment the basin and trigger strain partitioning in different areas. Magnetic fabrics are locally modified by Cenozoic compression, with intermediate and minimum axes distributed along girdles perpendicular to fold axes. Comparing all these results with macrostructures and mesostructural kinematic indicators, we conclude that the fine-grained hematite-bearing rocks carry a consistent magnetic fabric which can be used to reconstruct the basin history.

  13. Palaeomagnetic and structural constraints on 90° anticlockwise rotation in SW Mongolia during the Permo-Triassic: Implications for Altaid oroclinal bending. Preliminary palaeomagnetic results

    NASA Astrophysics Data System (ADS)

    Edel, Jean Bernard; Schulmann, Karel; Hanžl, Pavel; Lexa, Ondrej

    2014-11-01

    New and published paleomagnetic measurements from Trans Altai and South Gobi zones in south Mongolia document large tectonic motions in between Late Carboniferous and Triassic. Magnetic inclinations confirm equatorial position of south Mongolian terranes in Late Carboniferous-Permian times. The evolution of magnetic declinations indicates 90° anticlockwise rotation in between latest Carboniferous and Early Triassic of all studied tectonic units around the Eulerian pole located close to axis of Mongolian orocline. The anticlockwise rotation continues in Triassic being accompanied by a major drift to the north. The structural and published geochronological data suggest Carboniferous E-W shortening of the whole region resulting in N-S trend of all continental and oceanic geological units followed by orthogonal N-S shortening during Late Permian to Early Jurassic. Both paleomagnetic and geological data converge in a tectonic model of oroclinal bending of Mongolian ribbon continent, westerly back arc oceanic domain and Mongol-Okhotsk subduction zone to the east. The oroclinal bending model is consistent with the coincidence of the Eulerian pole of rotation with the structural axis of Mongolian orocline. In addition, the Mesozoic collisional tectonics is reflected by late remagnetizations due to formation of wide deformation fronts and hydrothermal activity.

  14. Response of vegetation to drought time-scales across global land biomes

    PubMed Central

    Vicente-Serrano, Sergio M.; Gouveia, Célia; Camarero, Jesús Julio; Beguería, Santiago; Trigo, Ricardo; López-Moreno, Juan I.; Azorín-Molina, César; Pasho, Edmond; Lorenzo-Lacruz, Jorge; Revuelto, Jesús; Morán-Tejeda, Enrique; Sanchez-Lorenzo, Arturo

    2013-01-01

    We evaluated the response of the Earth land biomes to drought by correlating a drought index with three global indicators of vegetation activity and growth: vegetation indices from satellite imagery, tree-ring growth series, and Aboveground Net Primary Production (ANPP) records. Arid and humid biomes are both affected by drought, and we suggest that the persistence of the water deficit (i.e., the drought time-scale) could be playing a key role in determining the sensitivity of land biomes to drought. We found that arid biomes respond to drought at short time-scales; that is, there is a rapid vegetation reaction as soon as water deficits below normal conditions occur. This may be due to the fact that plant species of arid regions have mechanisms allowing them to rapidly adapt to changing water availability. Humid biomes also respond to drought at short time-scales, but in this case the physiological mechanisms likely differ from those operating in arid biomes, as plants usually have a poor adaptability to water shortage. On the contrary, semiarid and subhumid biomes respond to drought at long time-scales, probably because plants are able to withstand water deficits, but they lack the rapid response of arid biomes to drought. These results are consistent among three vegetation parameters analyzed and across different land biomes, showing that the response of vegetation to drought depends on characteristic drought time-scales for each biome. Understanding the dominant time-scales at which drought most influences vegetation might help assessing the resistance and resilience of vegetation and improving our knowledge of vegetation vulnerability to climate change. PMID:23248309

  15. The time scale of the silicate weathering negative feedback on atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Colbourn, G.; Ridgwell, A.; Lenton, T. M.

    2015-05-01

    The ultimate fate of CO2 added to the ocean-atmosphere system is chemical reaction with silicate minerals and burial as marine carbonates. The time scale of this silicate weathering negative feedback on atmospheric pCO2 will determine the duration of perturbations to the carbon cycle, be they geological release events or the current anthropogenic perturbation. However, there has been little previous work on quantifying the time scale of the silicate weathering feedback, with the primary estimate of 300-400 kyr being traceable to an early box model study by Sundquist (1991). Here we employ a representation of terrestrial rock weathering in conjunction with the "GENIE" (Grid ENabled Integrated Earth system) model to elucidate the different time scales of atmospheric CO2 regulation while including the main climate feedbacks on CO2 uptake by the ocean. In this coupled model, the main dependencies of weathering—runoff, temperature, and biological productivity—were driven from an energy-moisture balance atmosphere model and parameterized plant productivity. Long-term projections (1 Myr) were conducted for idealized scenarios of 1000 and 5000 PgC fossil fuel emissions and their sensitivity to different model parameters was tested. By fitting model output to a series of exponentials we determined the e-folding time scale for atmospheric CO2 drawdown by silicate weathering to be ˜240 kyr (range 170-380 kyr), significantly less than existing quantifications. Although the time scales for reequilibration of global surface temperature and surface ocean pH are similar to that for CO2, a much greater proportion of the peak temperature anomaly persists on this longest time scale; ˜21% compared to ˜10% for CO2.

  16. Enhanced identification and exploitation of time scales for model reduction in stochastic chemical kinetics

    PubMed Central

    Gómez-Uribe, Carlos A.; Verghese, George C.; Tzafriri, Abraham R.

    2008-01-01

    Widely different time scales are common in systems of chemical reactions and can be exploited to obtain reduced models applicable to the time scales of interest. These reduced models enable more efficient computation and simplify analysis. A classic example is the irreversible enzymatic reaction, for which separation of time scales in a deterministic mass action kinetics model results in approximate rate laws for the slow dynamics, such as that of Michaelis–Menten. Recently, several methods have been developed for separation of slow and fast time scales in chemical master equation (CME) descriptions of stochastic chemical kinetics, yielding separate reduced CMEs for the slow variables and the fast variables. The paper begins by systematizing the preliminary step of identifying slow and fast variables in a chemical system from a specification of the slow and fast reactions in the system. The authors then present an enhanced time-scale-separation method that can extend the validity and improve the accuracy of existing methods by better accounting for slow reactions when equilibrating the fast subsystem. The resulting method is particularly accurate in systems such as enzymatic and protein interaction networks, where the rates of the slow reactions that modify the slow variables are not a function of the slow variables. The authors apply their methodology to the case of an irreversible enzymatic reaction and show that the resulting improvements in accuracy and validity are analogous to those obtained in the deterministic case by using the total quasi-steady-state approximation rather than the classical Michaelis–Menten. The other main contribution of this paper is to show how mass fluctuation kinetics models, which give approximate evolution equations for the means, variances, and covariances of the concentrations in a chemical system, can feed into time-scale-separation methods at a variety of stages. PMID:19123500

  17. Calculation of reattaching shear layers in divergent channel with a multiple-time-scale turbulence model

    NASA Technical Reports Server (NTRS)

    Kim, S.-W.

    1989-01-01

    Numerical calculations of turbulent reattaching shear layers in a divergent channel are presented. The turbulence is described by a multiple-time-scale turbulence model. The turbulent flow equations are solved by a control-volume based finite difference method. The computational results are compared with those obtained using k-epsilon turbulence models and algebraic Reynolds stress turbulence models. It is shown that the multiple-time-scale turbulence model yields significantly improved computational results than the other turbulence models in the region where the turbulence is in a strongly inequilibrium state.

  18. Unification of Small and Large Time Scales for Biological Evolution: Deviations from Power Law

    NASA Astrophysics Data System (ADS)

    Chowdhury, Debashish; Stauffer, Dietrich; Kunwar, Ambarish

    2003-02-01

    We develop a unified model that describes both “micro” and “macro” evolutions within a single theoretical framework. The ecosystem is described as a dynamic network; the population dynamics at each node of this network describes the “microevolution” over ecological time scales (i.e., birth, ageing, and natural death of individual organisms), while the appearance of new nodes, the slow changes of the links, and the disappearance of existing nodes accounts for the “macroevolution” over geological time scales (i.e., the origination, evolution, and extinction of species). In contrast to several earlier claims in the literature, we observe strong deviations from power law in the regime of long lifetimes.

  19. Some new stability properties of dynamic neural networks with different time-scales.

    PubMed

    Yu, Wen; Sandoval, Alejandro Cruz

    2006-06-01

    Dynamic neural networks with different time-scales include the aspects of fast and slow phenomenons. Some applications require that the equilibrium points of these networks to be stable. The main contribution of the paper is that Lyapunov function and singularly perturbed technique are combined to access several new stable properties of different time-scales neural networks. Exponential stability and asymptotic stability are obtained by sector and bound conditions. Compared to other papers, these conditions are simpler. Numerical examples are given to demonstrate the effectiveness of the theoretical results. PMID:17044240

  20. Climate-carbon cycle simulations of the Permian-Triassic boundary: Implications for the extinction event

    NASA Astrophysics Data System (ADS)

    Montenegro, A.; Spence, P.; Meissner, K. J.; Eby, M.; Melchin, M.; Johnston, S. T.

    2010-12-01

    The causes for the Permian-Triassic (PT) extinction, the largest mass extinction on record, remain unknown. The period is marked by large scale volcanic eruptions and evidence for widespread ocean anoxia, which have led to suggestions that these events generated, or played a part in, the extinction. Hypercapnia and ocean acidification caused by volcanic emissions of CO2 and CH4 have been put forward as potential kill mechanisms. We present the first PT boundary climate simulations conducted with a fully coupled climate-carbon cycle model, which allows for a direct evaluation of ocean acidity. The experiments also address the sensitivity of ocean circulation and oxygen levels to uncertainties in paleogeography and to different bottom topographies. Modeled temperature and precipitation are in good agreement with reconstructions and climate sensitive sediments. There is also good agreement between modeled vegetation and reconstructed biomes.The reduction in ocean pH brought about by the increase in atmospheric CO2 is biologically significant. Aragonite saturation levels are low enough to make the whole ocean unsuitable to present day corals and large areas of the ocean become unsaturated in relationship to calcite. No general bottom anoxia is reproduced. Modeled deep ocean O2 concentrations are not significantly impacted by changes in paleogeography and bathymetry, in a indication that a change in ocean dynamics resulting from climate warming is not sufficient by itself to generate widespread anoxic conditions during the period.

  1. Climate simulations of the Permian-Triassic boundary: Ocean acidification and the extinction event

    NASA Astrophysics Data System (ADS)

    Montenegro, A.; Spence, P.; Meissner, K. J.; Eby, M.; Melchin, M. J.; Johnston, S. T.

    2011-09-01

    The causes for the Permian-Triassic Boundary (PTB) extinction, the largest mass extinction on record, remain enigmatic. The period is marked by large-scale volcanic eruptions and evidence for widespread ocean anoxia, which have led to suggestions that these events generated, or played a part in, the extinction. Furthermore, hypercapnia and ocean acidification caused by volcanic emissions of CO2 and CH4 have been put forward as potential kill mechanisms. We present the first PTB climate simulations in which ocean acidity is evaluated directly with a coupled climate-carbon cycle model. The experiments also address the sensitivity of ocean circulation and oxygen levels to uncertainties in paleogeography and to different bottom topographies. Modeled temperature and precipitation-evaporation are in good agreement with reconstructions and climate-sensitive sediments. There is also good agreement between modeled vegetation and reconstructed biomes. The reduction in ocean pH brought about by the increase in atmospheric CO2 is biologically significant. Aragonite saturation levels are low enough to make the whole ocean unsuitable to aragonitic species, and large areas of the ocean become unsaturated in relationship to calcite. No general bottom anoxia is reproduced. Modeled deep ocean O2 concentrations are not significantly impacted by changes in paleogeography and bathymetry, an indication that in our model a change in ocean dynamics resulting from climate warming is not sufficient by itself to generate widespread anoxic conditions during the period.

  2. Influence of the Time Scale on the Construction of Financial Networks

    PubMed Central

    Emmert-Streib, Frank; Dehmer, Matthias

    2010-01-01

    Background In this paper we investigate the definition and formation of financial networks. Specifically, we study the influence of the time scale on their construction. Methodology/Principal Findings For our analysis we use correlation-based networks obtained from the daily closing prices of stock market data. More precisely, we use the stocks that currently comprise the Dow Jones Industrial Average (DJIA) and estimate financial networks where nodes correspond to stocks and edges correspond to none vanishing correlation coefficients. That means only if a correlation coefficient is statistically significant different from zero, we include an edge in the network. This construction procedure results in unweighted, undirected networks. By separating the time series of stock prices in non-overlapping intervals, we obtain one network per interval. The length of these intervals corresponds to the time scale of the data, whose influence on the construction of the networks will be studied in this paper. Conclusions/Significance Numerical analysis of four different measures in dependence on the time scale for the construction of networks allows us to gain insights about the intrinsic time scale of the stock market with respect to a meaningful graph-theoretical analysis. PMID:20949124

  3. Systematic Land-Surface-Model Performance Evaluation on different time scales

    NASA Astrophysics Data System (ADS)

    Mahecha, M. D.; Jung, M.; Reichstein, M.; Beer, C.; Braakhekke, M.; Carvalhais, N.; Lange, H.; Lasslop, G.; Le Maire, G.; Seneviratne, S. I.; Vetter, M.

    2008-12-01

    Keeping track of the space--time evolution of CO2--, and H2O--fluxes between the terrestrial biosphere and atmosphere is essential to our understanding of current climate. Monitoring fluxes at site level is one option to characterize the temporal development of ecosystem--atmosphere interactions. Nevertheless, many aspects of ecosystem--atmosphere fluxes become meaningful only when interpreted in time over larger geographical regions. Empirical and process based models play a key role in spatial and temporal upscaling exercises. In this context, comparative model performance evaluations at site level are indispensable. We present a model evaluation scheme which investigates the model-data agreement separately on different time scales. Observed and modeled time series were decomposed by essentially non parametric techniques into subsignals (time scales) of characteristic fluctuations. By evaluating the extracted subsignals of observed and modeled C--fluxes (gross and net ecosystem exchange, GEE and NEE, and terrestrial ecosystem respiration, TER) separately, we obtain scale--dependent performances for the different evaluation measures. Our diagnostic model comparison allows uncovering time scales of model-data agreement and fundamental mismatch. We focus on the systematic evaluation of three land--surface models: Biome--BGC, ORCHIDEE, and LPJ. For the first time all models were driven by consistent site meteorology and compared to respective Eddy-Covariance flux observations. The results show that correct net C--fluxes may result from systematic (simultaneous) biases in TER and GEE on specific time scales of variation. We localize significant model-data mismatches of the annual-seasonal cycles in time and illustrate the recurrence characteristics of such problems. For example LPJ underestimates GEE during winter months and over estimates it in early summer at specific sites. Contrary, ORCHIDEE over-estimates the flux from July to September at these sites. Finally, the study also uncovers why significant model-data differences are observable on intermediate time scales, but highly uncertain in low frequency components. The work further investigates time localized model data mismatches in relation to climate conditions.

  4. Kinetics of charge transfer at the lipid bilayer-water interface on the nanosecond time scale.

    PubMed Central

    Woodle, M; Zhang, J W; Mauzerall, D

    1987-01-01

    Advances in instrumentation allow electrical measurements across the planar lipid bilayer to be made with nanosecond time resolution. The electron transfer reaction between photoexcited magnesium octaethylporphyrin in the lipid to a variety of ionically charged acceptors in the water is found to be purely dynamic over a wide range of concentrations of acceptors and up to the time constant of the apparatus, 4 ns. The saturation of the amplitude of the photovoltage with increasing concentration of acceptor is caused by the finite lifetime of the excited state, not by formation of a static pigment-acceptor complex. The reactions are an excellent probe of the lipid-water interface over an extended time scale. No appreciable barrier to reaction exists at this interface beyond the 5-ns time. That is, any water or choline group structure may be evanescent on this time scale. Electrostatic interactions indicate that the acceptor molecules penetrate to the level of the phosphocholine groups with differing orientations. It will be possible to extend the time scale into the picosecond range by decreasing the response time and by deconvolutions. PMID:3676439

  5. Allometric scaling and prediction of concentration-time profiles of coagulation factors in humans from animals.

    PubMed

    Mahmood, Iftekhar

    2013-09-01

    Allometric scaling is a useful tool in early drug development and can be used for the prediction of human pharmacokinetic (PK) parameters from animal PK parameters. The main objective of this work was to predict concentration-time profiles of coagulation factors in humans in a multi-compartment system using animal PK parameters. The prediction of concentration-time profiles in humans in a multi-compartment system was based on the predicted values of clearance and volumes of distribution (V(c), V(ss) and V(?)) from animals. Five coagulation factors from the literature were chosen that were described by two-compartment model in both humans and animals. Clearance and volumes of distribution from animals were allometrically scaled to humans and then were used to predict concentration-time profiles in humans. The predicted concentration-time profile for a given coagulation factor was accurate for most of the time points. Percent prediction error range varied across coagulation factors. The prediction error >50% was observed either at 1 or a maximum of two time points for a given drug. The study indicated that the allometric scaling can be useful in the prediction of concentration-time profiles of coagulation factors in humans from animals and may be helpful in designing a first-in-human study. PMID:23391211

  6. Local and Catchment-Scale Water Storage Changes in Northern Benin Deduced from Gravity Monitoring at Various Time-Scales

    NASA Astrophysics Data System (ADS)

    Hinderer, J.; Hector, B.; Séguis, L.; Descloitres, M.; Cohard, J.; Boy, J.; Calvo, M.; Rosat, S.; Riccardi, U.; Galle, S.

    2013-12-01

    Water storage changes (WSC) are investigated by the mean of gravity monitoring in Djougou, northern Benin, in the frame of the GHYRAF (Gravity and Hydrology in Africa) project. In this area, WSC are 1) part of the control system for evapotranspiration (ET) processes, a key variable of the West-African monsoon cycle and 2) the state variable for resource management, a critical issue in storage-poor hard rock basement contexts such as in northern Benin. We show the advantages of gravity monitoring for analyzing different processes in the water cycle involved at various time and space scales, using the main gravity sensors available today (FG5 absolute gravimeter, superconducting gravimeter -SG- and CG5 micro-gravimeter). The study area is also part of the long-term observing system AMMA-Catch, and thus under intense hydro-meteorological monitoring (rain, soil moisture, water table level, ET ...). Gravity-derived WSC are compared at all frequencies to hydrological data and to hydrological models calibrated on these data. Discrepancies are analyzed to discuss the pros and cons of each approach. Fast gravity changes (a few hours) are significant when rain events occur, and involve different contributions: rainfall itself, runoff, fast subsurface water redistribution, screening effect of the gravimeter building and local topography. We investigate these effects and present the statistical results of a set of rain events recorded with the SG installed in Djougou since July 2010. The intermediate time scale of gravity changes (a few days) is caused by ET and both vertical and horizontal water redistribution. The integrative nature of gravity measurements does not allow to separate these different contributions, and the screening from the shelter reduces our ability to retrieve ET values. Also, atmospheric corrections are critical at such frequencies, and deserve some specific attention. However, a quick analysis of gravity changes following rain events shows that the values are in accordance with expected ET values (up to about 5mm/day). Seasonal WSC are analyzed since 2008 using FG5 absolute gravity measurements four times a year and since 2010 using the continuous SG time series. They can reach up to 12 microGal (?270mm) and show a clear interannual variability, as can be expected from rainfall variability in the area. This data set allows some estimates of an average specific yield for the local aquifer, together with a scaling factor for Magnetic Resonance Soundings-derived water content.

  7. Time scale separation in the low temperature East model: Rigorous results

    E-print Network

    Paul Chleboun; Alessandra Faggionato; Fabio Martinelli

    2013-02-07

    We consider the non-equilibrium dynamics of the East model, a linear chain of 0-1 spins evolving under a simple Glauber dynamics in the presence of a kinetic constraint which forbids flips of those spins whose left neighbour is 1. We focus on the glassy effects caused by the kinetic constraint as $q\\downarrow 0$, where $q$ is the equilibrium density of the 0's. Specifically we analyse time scale separation and dynamic heterogeneity, i.e. non-trivial spatio-temporal fluctuations of the local relaxation to equilibrium, one of the central aspects of glassy dynamics. For any mesoscopic length scale $L=O(q^{-\\gamma})$, $\\gammaseparated by a factor $q^{-a}$, $a=a(\\gamma)>0$, provided that $d'/d$ is large enough independently of $q$. In particular, the evolution of mesoscopic domains, i.e. maximal blocks of the form $111..10$, occurs on a time scale which depends sharply on the size of the domain, a clear signature of dynamic heterogeneity. Finally we show that no form of time scale separation can occur for $\\gamma=1$, i.e. at the equilibrium scale $L=1/q$, contrary to what was previously assumed in the physical literature based on numerical simulations.

  8. Comprehensive database on Induan (Lower Triassic) to Sinemurian (Lower Jurassic) marine bivalve genera and their paleobiogeographic record

    E-print Network

    Ros-Franch, Sonia; Marquez-Aliaga, Ana; Damborenea, Susana

    2014-04-10

    Marine bivalve genera that were described or mentioned for Triassic and Lower Jurassic deposits worldwide are reviewed in terms of their validity, stratigraphic range, paleogeographic distribution, paleoautecology, and ...

  9. A Statistical Analysis of the Scaling Laws for the Confinement Time Distinguishing between Core and Edge

    NASA Astrophysics Data System (ADS)

    Peluso, E.; Gelfusa, M.; Murari, A.; Lupelli, I.; Gaudio, P.

    The H mode of confinement in Tokamaks is characterized by a thin region of high gradients, located at the edge of the plasma and called the Edge Transport Barrier. Even if various theoretical models have been proposed for the interpretation of the edge physics, the main empirical scaling laws of the plasma confinement time are expressed in terms of global plasma parameters and they do not discriminate between the edge and core regions. Moreover all the scaling laws are assumed to be power law monomials. In the present paper, a new methodology is proposed to investigate the validity of both assumptions. The approach is based on Symbolic Regression via Genetic Programming and allows first the extraction of the most statistically reliable models from the available experimental data in the ITPA database. Non linear fitting is then applied to the mathematical expressions found by Symbolic regression. The obtained scaling laws are compared with the traditional scalings in power law form.

  10. Different Time-Scale Relaxation Dynamics in Organic Supramolecular Ferroelectrics Studied by Linear and Nonlinear Spectroscopy

    NASA Astrophysics Data System (ADS)

    Umanodan, Tsugumi; Tanaka, Sei'ichi; Naruse, Suguru; Ishikawa, Tadahiko; Onda, Ken; Koshihara, Shin-ya; Horiuchi, Sachio; Okimoto, Yoichi

    2015-07-01

    Time-resolved linear and nonlinear optical responses were investigated in an organic supramolecular ferroelectric material composed of protonated 2,3-di(2-pyridinyl)pyrazine (H-dppz) and deprotonated chloranilic acid (Hca). We irradiated nanosecond laser pulses (? = 532 nm) on the crystal, pumped the intramolecular excitation of the Hca molecule, and observed a clear redshift of the molecular vibrational modes of C=O and C-O- just after the photoexcitation. Each softened mode gradually relaxed on different time scales, indicating that the electrons of the Hca molecules were redistributed after the photoexcitation. By the same excitation, a large suppression of the second-harmonic (SH) intensity was observed, driven by the macroscopic disordering of the transferred protons. The decay time of the SH intensity was longer than those of the vibrational modes, suggesting that the microscopic vibrations and macroscopic ferroelectricity have dynamics on different time scales.

  11. Linking Time and Space Scales in Distributed Hydrological Modelling - a case study for the VIC model

    NASA Astrophysics Data System (ADS)

    Melsen, Lieke; Teuling, Adriaan; Torfs, Paul; Zappa, Massimiliano; Mizukami, Naoki; Clark, Martyn; Uijlenhoet, Remko

    2015-04-01

    One of the famous paradoxes of the Greek philosopher Zeno of Elea (~450 BC) is the one with the arrow: If one shoots an arrow, and cuts its motion into such small time steps that at every step the arrow is standing still, the arrow is motionless, because a concatenation of non-moving parts does not create motion. Nowadays, this reasoning can be refuted easily, because we know that motion is a change in space over time, which thus by definition depends on both time and space. If one disregards time by cutting it into infinite small steps, motion is also excluded. This example shows that time and space are linked and therefore hard to evaluate separately. As hydrologists we want to understand and predict the motion of water, which means we have to look both in space and in time. In hydrological models we can account for space by using spatially explicit models. With increasing computational power and increased data availability from e.g. satellites, it has become easier to apply models at a higher spatial resolution. Increasing the resolution of hydrological models is also labelled as one of the 'Grand Challenges' in hydrology by Wood et al. (2011) and Bierkens et al. (2014), who call for global modelling at hyperresolution (~1 km and smaller). A literature survey on 242 peer-viewed articles in which the Variable Infiltration Capacity (VIC) model was used, showed that the spatial resolution at which the model is applied has decreased over the past 17 years: From 0.5 to 2 degrees when the model was just developed, to 1/8 and even 1/32 degree nowadays. On the other hand the literature survey showed that the time step at which the model is calibrated and/or validated remained the same over the last 17 years; mainly daily or monthly. Klemeš (1983) stresses the fact that space and time scales are connected, and therefore downscaling the spatial scale would also imply downscaling of the temporal scale. Is it worth the effort of downscaling your model from 1 degree to 1/24 degree, if in the end you only look at monthly runoff? In this study an attempt is made to link time and space scales in the VIC model, to study the added value of a higher spatial resolution-model for different time steps. In order to do this, four different VIC models were constructed for the Thur basin in North-Eastern Switzerland (1700 km²), a tributary of the Rhine: one lumped model, and three spatially distributed models with a resolution of respectively 1x1 km, 5x5 km, and 10x10 km. All models are run at an hourly time step and aggregated and calibrated for different time steps (hourly, daily, monthly, yearly) using a novel Hierarchical Latin Hypercube Sampling Technique (Vo?echovský, 2014). For each time and space scale, several diagnostics like Nash-Sutcliffe efficiency, Kling-Gupta efficiency, all the quantiles of the discharge etc., are calculated in order to compare model performance over different time and space scales for extreme events like floods and droughts. Next to that, the effect of time and space scale on the parameter distribution can be studied. In the end we hope to find a link for optimal time and space scale combinations.

  12. Time Domain Optical Studies of Dynamics in Supercooled o-Terphenyl: Comparison to Mode Coupling Theory on Fast and Slow Time Scales

    E-print Network

    Fayer, Michael D.

    Time Domain Optical Studies of Dynamics in Supercooled o-Terphenyl: Comparison to Mode Coupling Theory on Fast and Slow Time Scales S. D. Gottke, David D. Brace, G. Hinze, and M. D. Fayer* Department of temperatures and time scales using optical heterodyne detected optical Kerr effect techniques. A combination

  13. RSLAM: A System for Large-Scale Mapping in Constant-Time Using Stereo

    Microsoft Academic Search

    Christopher Mei; Gabe Sibley; Mark Cummins; Paul Newman; Ian Reid

    2011-01-01

    Large scale exploration of the environment requires a constant time estimation engine. Bundle adjustment or pose relaxation\\u000a do not fulfil these requirements as the number of parameters to solve grows with the size of the environment. We describe\\u000a a relative simultaneous localisation and mapping system (RSLAM) for the constant-time estimation of structure and motion using\\u000a a binocular stereo camera system

  14. Application-Driven Compression for Visualizing Large-Scale Time-Varying Data

    Microsoft Academic Search

    Chaoli Wang; Hongfeng Yu; Kwan-Liu Ma

    2010-01-01

    We advocate an application-driven approach to compressing and rendering large-scale time-varying scientific-simulation data. Scientists often have specific visualization tasks in mind based on certain domain knowledge. For example, in the context of time-varying, multivariate volume-data visualization, a scientist's domain knowledge might include the salient isosurface of interest for some variable. Given this knowledge, the scientist might want to observe spatiotemporal

  15. Application-Driven Compression for Visualizing Large-Scale Time-Varying Volume Data

    Microsoft Academic Search

    Chaoli Wang; Hongfeng Yu; Kwan-Liu Ma

    2009-01-01

    We present an application-driven approach to compressing large-scale time-varying volume data. Our method identifies a reference feature to partition the data into space-time blocks, which are compressed with various precisions depending on their association to the feature. Runtime decompression is performed with bit-wise texture packing and deferred filtering. We show that our method achieves high compression rates and interactive rendering

  16. An Open and Scalable Emulation Infrastructure for Large-Scale Real-Time Network Simulations

    Microsoft Academic Search

    Jason Liu; Scott Mann; Nathanael Van Vorst; Keith Hellman

    2007-01-01

    We present a software infrastructure that embeds physical hosts in a simulated network. Aiming to create a large- scale real-time virtual network testbed, our real-time interactive simulation approach combines the advantages of both simulation and emulation, by maintaining flexibility of the simulation models and increasing fidelity as real systems are included in the simu- lation. In our approach, real-world distributed

  17. Reliable H? control of multiple time scales singularly perturbed systems with sensor failure

    Microsoft Academic Search

    A. Tellili; M. N. Abdelkrim; M. Benrejeb

    2007-01-01

    This paper studies the reliable H? control for linear time-invariant multiparameter singularly perturbed systems against sensor failures. By time-scale decomposition, the full-order system is decomposed into slow and fast subsystems. After designing a reliable H? controller for the global system, three reduced reliable H? sub-controllers based on the slow and fast problems are obtained through the manipulation of the algebraic

  18. New time-scale criteria for model simplification of bio-reaction systems

    Microsoft Academic Search

    Junwon Choi; Kyung-won Yang; Tai-yong Lee; Sang Yup Lee

    2008-01-01

    BACKGROUND: Quasi-steady state approximation (QSSA) based on time-scale analysis is known to be an effective method for simplifying metabolic reaction system, but the conventional analysis becomes time-consuming and tedious when the system is large. Although there are automatic methods, they are based on eigenvalue calculations of the Jacobian matrix and on linear transformations, which have a high computation cost. A

  19. Performance Comparison of Dynamic Voltage Scaling Algorithms for Hard Real-Time Systems

    Microsoft Academic Search

    Woonseok Kim; Dongkun Shin; Han-saem Yun; Jihong Kim; Sang Lyul Min

    2002-01-01

    Dynamic voltage scaling (DVS) is an effective low-powerdesign technique for embedded real-time systems. In recentyears, many DVS algorithms have been proposed for reducingthe energy consumption of embedded hard real-time systems.However, the proposed DVS algorithms were not quantitativelyevaluated under a unified framework, making it adifficult task to select an appropriate DVS algorithm for agiven application\\/system. In this paper, we compare severalkey

  20. The National Bureau of Standards Atomic Time Scales: Generation, Dissemination, Stability, and Accuracy

    Microsoft Academic Search

    David W. Allan; James E. Gray; H. E. Machlan

    1972-01-01

    The independent atomic time scale at the National Bureau of Standards AT(NBS), is based upon an ensemble of continuously operating cesium clocks calibrated occasionally by an NBS primary frequency standard. The data of frequency calibrations and interclock comparisons are statistically processed to provide nearly optimum time stability and frequency accuracy. The long-term random fluctuation of AT(NBS) due to nondeterministic perturbations

  1. Conodont color and surface textural alteration in the Muschelkalk (Triassic) of the Silesian-Cracow Zn-Pb district, Poland

    USGS Publications Warehouse

    Repetski, J.E.; Narkiewicz, M.

    1996-01-01

    Limestone and dolostone samples were collected from sites within and adjacent to ore zones in the Trzebionka mine, Silesia-Cracow zinc-lead mining district, southern Poland, to assess the level of thermal alteration of the enclosed conodonts, via the color alteration index (CAI) technique, and to study any surface alteration effects on these microfossils. Additional conodont sampling from stratigraphic levels correlative with the horizons being mined in the Trzebionka mine was accomplished at four surface and two borehole localities in the district, to compare the CAI and surface alteration effects at these, commercially non-mineralized, localities with those effects in the mine. Data show that: 1. The overall background thermal level of the Triassic strata studied, presumably due to only shallow burial, is very low: CAI = 1; in the range of 50 to 80??C. 2. CAI values in the ore zones in the Trzebionka mine are slightly higher than this regional background: 1+ to 1.5 (in the range ???50 to 90??C minimum heating over geologic time of about 0.1 to more than 1 m. y.). This implies that heating "events" of higher temperatures affecting the conodonts, including the passage of the local ore-bearing solutions, were of rather short duration(s), on the order of about 1,000 to 50,000 years. CAI data from the Trzebionka Mine is consistent with temperature data from fluid inclusions, indicating ore-bearing fluid temperatures in the 100 to 138??C range, and the scenario that these fluids were resident in these strata for a geologically short period. 3. Conodonts from both surface and subsurface samples rarely show surface corrosion effects, but tend to show apatite overgrowths. These overgrowths vary in degree of development, but are consistent for each morphological type of conodont element, and qualitatively are consistent in each sample observed. 4. Ichthyoliths (fish teeth, spines, and scales), found in most of the samples, do not exhibit either mineral overgrowths or apparent corrosion effects to the extent seen in the conodont elements. 5. Ichthyoliths show color alteration effects that are consistent within-sample but which are very different from the CAI values of conodonts in the same sample. The color alteration of the fish teeth might be of value as a thermal maturation index in the future, if and when calibrated through controlled laboratory experimental testing, but at present cannot and should not be used as equivalent to conodont CAI.

  2. Altitude and configuration of the potentiometric surface in the Triassic sandstones and shales, northeastern Chester County, Pennsylvania, September 1987 through January 1988

    USGS Publications Warehouse

    Senior, Lisa A.; Garges, John A.

    1989-01-01

    The altitude of the water levels in the Triassic sandstones and shales in northeastern Chester County is shown on a map at a scale of 1:24,000. The map is based on water levels in 173 non-pumping drilled and dug wells measured in 1956 and 1965, and on the altitude of two springs that were flowing in November and December 1987. Water level altitudes are contoured at an interval of 20 ft. The surface defined by the contoured water levels may approximately represent the water table. Water table altitudes range from 379 ft to less than 80 ft above sea level. (USGS)

  3. How Do Young Children's Spatio-Symbolic Skills Change over Short Time scales?

    ERIC Educational Resources Information Center

    Tsubota, Yoko; Chen, Zhe

    2012-01-01

    Three experiments were designed to examine how experience affects young children's spatio-symbolic skills over short time scales. Spatio-symbolic reasoning refers to the ability to interpret and use spatial relations, such as those encountered on a map, to solve symbolic tasks. We designed three tasks in which the featural and spatial…

  4. BROWNIAN MOTION INDEXED BY A TIME SCALE DAVID GROW AND SUMAN SANYAL

    E-print Network

    Sanyal, Suman

    BROWNIAN MOTION INDEXED BY A TIME SCALE DAVID GROW AND SUMAN SANYAL Abstract. In this paper we generalize Wiener's existence result for one- dimensional Brownian motion by constructing a suitable, we obtain a local H¨older-continuity result for the sample paths of generalized Brownian motion

  5. Regional-Scale Simulations of Wildland Fire Spread Informed by Real-Time Flame Front Observations

    E-print Network

    Regional-Scale Simulations of Wildland Fire Spread Informed by Real-Time Flame Front Observations M, University of Maryland, College Park, MD 20742, USA. Abstract This study presents an analysis of wildland fire propagation. Data assimilation is an efficient strategy, initially developed

  6. MULTI-TIME SCALE ANALYSIS OF SUGARCANE WITHIN-FIELD VARIABILITY: IMPROVED CROP DIAGNOSIS USING SATELLITE

    E-print Network

    Paris-Sud XI, Université de

    1 MULTI-TIME SCALE ANALYSIS OF SUGARCANE WITHIN-FIELD VARIABILITY: IMPROVED CROP DIAGNOSIS USING condition. To test this hypothesis, we analyzed the within-field variability of a sugarcane crop at seasonal, and soil depth) and cropping (harvest date) factors. The analysis was based on a sugarcane field vegetation

  7. Two time scale output feedback regulation for ill-conditioned systems

    NASA Technical Reports Server (NTRS)

    Calise, A. J.; Moerder, D. D.

    1986-01-01

    Issues pertaining to the well-posedness of a two time scale approach to the output feedback regulator design problem are examined. An approximate quadratic performance index which reflects a two time scale decomposition of the system dynamics is developed. It is shown that, under mild assumptions, minimization of this cost leads to feedback gains providing a second-order approximation of optimal full system performance. A simplified approach to two time scale feedback design is also developed, in which gains are separately calculated to stabilize the slow and fast subsystem models. By exploiting the notion of combined control and observation spillover suppression, conditions are derived assuring that these gains will stabilize the full-order system. A sequential numerical algorithm is described which obtains output feedback gains minimizing a broad class of performance indices, including the standard LQ case. It is shown that the algorithm converges to a local minimum under nonrestrictive assumptions. This procedure is adapted to and demonstrated for the two time scale design formulations.

  8. A model for universal time scale of vortex ring formation Kamran Mohseni

    E-print Network

    Mohseni, Kamran

    A model for universal time scale of vortex ring formation Kamran Mohseni Division of Engineering for formation of vortex rings generated through impulsively started jets is considered. The model is based in the Norbury family. The nondimensional stroke length L/D referred to as ``formation number,'' following Gharib

  9. Observations of near-inertial surface currents off Oregon: Decorrelation time and length scales

    NASA Astrophysics Data System (ADS)

    Kim, Sung Yong; Kosro, P. Michael

    2013-07-01

    High-resolution (km in space and hourly in time) surface currents observed by an array of high-frequency radars off Oregon are analyzed to quantify the decorrelation time and length scales of their near-inertial motions. The near-inertial surface currents are dominantly clockwise with amplitudes of 9-12 cm s-1. However, they appear asymmetric and elliptical as a result of counterclockwise inertial motions with magnitudes in a range of 2-5 cm s-1. The decorrelation time and length scales are computed from the decay slope of the near-inertial peak and the spatial coherence in the near-inertial frequency band, respectively. Decorrelation time scales of clockwise near-inertial motions increase from 2 days nearshore (within 30 km from the coast) to 6 days offshore, and their length scales increase from 30 to 90 km seaward possibly due to coastal inhibition. The local spatial coherence has an exponentially decaying structure for both clockwise and counterclockwise rotations, and their phases propagate northwestward (offshore) for clockwise and northeastward (onshore) for counterclockwise rotations.

  10. Astronomic calibration of the late Oligocene through early Miocene geomagnetic polarity time scale

    E-print Network

    Zachos, James

    Astronomic calibration of the late Oligocene through early Miocene geomagnetic polarity time scale) span the late Oligocene through early Miocene ( f24­16 Ma) at a temporal resolution of f5 ky. Over. In an initial age model, we use the newly derived age of the Oligocene/Miocene (O/M) boundary of 23.0 Ma

  11. The role of ocean gateways on cooling climate on long time scales Willem P. Sijp a,

    E-print Network

    Sijp, Willem

    greenhouse climate icehouse climate polar warmth We examine ocean changes in response to changesThe role of ocean gateways on cooling climate on long time scales Willem P. Sijp a, , Anna S. von climates, namely the Turonian and the Eocene simulations, systematically exhibit warm deep ocean

  12. Towards Visualising Temporal Features in Large Scale Microarray Time-Series Data

    Microsoft Academic Search

    Paul Craig; Jessie B. Kennedy; Andrew Cumming

    2002-01-01

    Current techniques for visualising large-scale microarray data are unable to present temporal features without reducing the number of elements being displayed. This paper introduces a technique that overcomes this problem by combining a novel display technique, which operates over a continuous temporal subset of the time series, with direct manipulation of the parameters defining the subset.

  13. Microsecond time scale thermocouple temperature measurements in solid penetrated by a shaped charge jet

    Microsoft Academic Search

    Juxian Gao; Rongshang Bai

    1995-01-01

    The development of microsecond time scale temperature measurements in shock-loaded solids is briefly reviewed. The feasibility of making thermocouple temperature measurements near a cavity created by a shaped charge jet in medium carbon steel and glass fiber reinforced epoxy composite solid targets has been studied. Thermal diffusion calculations demonstrated that these measurements were feasible if the foil thermocouple was on

  14. Ground Water Quantity and Quality Management: Agricultural Production and Aquifer Salinization over Long Time Scales

    Microsoft Academic Search

    Keith C. Knapp; Kenneth A. Baerenklau

    2006-01-01

    An economic model of ground water salinization is developed. Starting from a full, high-quality aquifer, there is an initial extraction period, an intermediate waste disposal period, and a final drainage period. Drainage management is initially source control and reuse, but eventually culminates in evaporation basins and a system steady-state. This process occurs over long time scales but is consistent with

  15. Large scale time variability from high-low SST -filling the

    E-print Network

    Stuttgart, Universität

    -On (GFO) 2 Low-low © CSR Texas · K-Band (Laser) · GPS · Accelerometer ~ 5 year data gap year #12;OtherLarge scale time variability from high-low SST - filling the gap between GRACE and GFO Matthias gravity field missions 3 High-low GOCE GOCE © ESA © EADS Astrium SWARM year #12;Previous CHAMP studies

  16. Observations of decadal time scale salinity changes in the subtropical thermocline of the North Pacific Ocean

    E-print Network

    Riser, Stephen C.

    Observations of decadal time scale salinity changes in the subtropical thermocline of the North Mixed layer Hydrological cycle a b s t r a c t Data from Argo floats indicate that significant salinity decades, including observations obtained as part of the WOCE hydrographic program. Such a salinity

  17. Development and Preliminary Validation of the Time Management for Exercise Scale

    ERIC Educational Resources Information Center

    Hellsten, Laurie-ann M.; Rogers, W. Todd

    2009-01-01

    The purpose of this study was to collect preliminary validity evidence for a time management scale for exercise. An initial pool of 91 items was developed from existing literature. Ten exercise/health psychologists evaluated each of the items in terms of relevance and representativeness. Forty-nine items met all criteria. Exploratory factor…

  18. Multiple-time-scale perturbation theory: Radiative decay of coupled atomic states

    Microsoft Academic Search

    G. L. Brooks Jr.; L. M. Scarfone

    1982-01-01

    The spontaneous radiative decay to the ground state of an atomic system initially in the higher of two excited states, coupled in a radiationless fashion by an external field, is investigated by the method of multiple-time-scale perturbation theory. The coupled differential equations of motion for the probability amplitudes are solved to second order, while the usual secular behavior of conventional

  19. Approximate Group Analysis and Multiple Time Scales Method for the Approximate Boussinesq Equation

    Microsoft Academic Search

    Svetlana A. Kordyukova

    2006-01-01

    This paper is devoted to investigation of the approximate Boussinesq equation by methods of the approximate symmetry analysis of partial differential equations with a small parameter developed by Baikov, Gazizov and Ibragimov. We combine these methods with the method of multiple time scales to extend the domain of definition of approximate group invariant solutions of the approximate Boussinesq equation.

  20. UHURU observations of short-time-scale variations of the Crab

    Microsoft Academic Search

    W. Forman; R. Giacconi; C. Jones; E. Schreier; H. Tananbaum

    1974-01-01

    We have analyzed Uhuru X-ray observations of the Crab and found statistically significant variability in the intensity on time scales of several tenths of a second. Our results imply either that the X-ray emission from the pulsar NP 0532 is highly variable or that we have observed a previously undetected compact source of X-rays.