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Sample records for triassic time scale

  1. 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

    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.

  2. A nonmarine record of eccentricity forcing through the Upper Triassic of southwest England and its correlation with the Newark Basin astronomically calibrated geomagnetic polarity time scale from North America

    NASA Astrophysics Data System (ADS)

    Kemp, David B.; Coe, Angela L.

    2007-11-01

    The Late Triassic was a time of major environmental change, yet the precise chronology of events is poorly constrained owing to the nonmarine nature of most preserved Upper Triassic strata and the difficulty in correlating sections. St. Audrie's Bay, southwest England, has been the focus of many studies on this interval of time and is one of the proposed sections for the base Jurassic global stratotype section and point (GSSP). In this study, lacustrine deposits exposed at St. Audrie's Bay have been used to construct a floating astronomical time scale for ˜3.7 m.y. of the Late Triassic based on the recognition of ˜100 k.y. eccentricity cycles in rock color. In addition, we have correlated this time scale with an existing magnetostratigraphy through the same succession and produced an astronomically calibrated record of geomagnetic polarity. Using a novel statistical procedure, we have determined the correlation between this succession and the Late Triassic geomagnetic polarity time scale of the Newark Basin, North America, on which the current (2004) geological time scale is based. Our results show unequivocally that the studied St. Audrie's Bay succession represents part of the Norian and we demonstrate for the first time that cyclostratigraphy can be used in the correlation of Mesozoic strata between North America and Europe.

  3. Status Report on the 40Ar/39Ar and U/Pb Dating of Tuffs in the Dewey Lake Formation of West Texas Towards Constraining the Permo-Triassic Magnetostratigraphic Time Scale

    NASA Astrophysics Data System (ADS)

    Chang, S.; Renne, P. R.; Mundil, R.

    2007-12-01

    A detailed magnetic polarity time scale for the Permo-Triassic Boundary interval, critical for correlating events in marine and terrestrial paleoenvironments, is not yet well-established. Recently, late Permian magnetostratigraphic studies have been reported for non-marine sections in Europe and South Africa (Szurlies et al., 2003; Nawrocki, 2004; Ward et al., 2005). However, these sections are devoid of index fossil suitable for correlation with marine successions and also lack age constraints from radioisotopic dating methods. In other words, it is dubious to correlate these magnetostratigraphic data with the GSSP Permo-Triassic boundary and mass extinction. The Dewey Lake red beds formation of West Texas, believed to be the youngest Permian formation in North America, has yielded high-quality paleomagnetic data (Molina-Garza et al., 1989; Steiner, 2001) and contains several silicic tuffs potentially enabling high-resolution calibration of the magnetic polarity time scale in this critical age range. The tuffs have yet to be placed into a regional stratigraphic or magnetostratigraphic framework, and it is unclear exactly how many distinct eruptive units are represented by the 7 distinct samples collected to date from widely separated (>160 km) localities. 40Ar/39Ar (sanidine and biotite) and U/Pb (zircon) studies reveal that all 7 sampled tuffs were probably erupted within several hundred ka of the Permo-Triassic boundary as dated at the Meishan GSSP section (Renne et al., 1995; Mundil et al., 2004) but results thus far are inadequate to convincingly resolve age differences between the various samples. U/Pb dating of some samples is severely challenged by Pb-loss from the zircons despite application of the Mattinson (2005) annealing/chemical abrasion technique. 40Ar/39Ar data have been obtained from as many as four different irradiations in order to reduce neutron fluence related error. We observe the familiar ~1% bias between U/Pb and 40Ar/39Ar ages. Biotite

  4. TRIASSIC: the Time-Resolved Industrial Alpha-Source Scanning Induced Current microscope

    NASA Astrophysics Data System (ADS)

    Pallone, Arthur

    Time-resolved ion beam induced current (TRIBIC) microscopy yields useful information such as carrier mobility and lifetimes in semiconductors and defect locations in devices; however, traditional TRIBIC uses large, expensive particle accelerators that require specialized training to operate and maintain. The time-resolved industrial alpha-source scanning induced current (TRIASSIC) microscope transforms TRIBIC by replacing the particle accelerator facility with an affordable, tabletop instrument suitable for use in research and education at smaller colleges and universities. I will discuss the development of, successes with, setbacks to and future directions for TRIASSIC.

  5. 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.

  6. Timing of Carbon isotope excursions during the late Triassic and early Jurassic

    NASA Astrophysics Data System (ADS)

    Yager, J. A.; West, A. J.; Corsetti, F. A.; Berelson, W.; Bottjer, D. J.; Rosas, S.

    2015-12-01

    The emplacement of the Central Atlantic Magmatic Province during the late Triassic and early Jurassic is implicated in the end-Triassic mass extinction and is associated with dramatic increases in atmospheric pCO2. Changes in the isotopic composition of CO2 as recorded on land and in the ocean have been observed in many sections worldwide, but the timing and causes of the changes are debated. Recent high-resolution ash bed dating (Schaltegger et al., 2008; Schoene et al., 2010; Guex et al., 2012; Wotzlaw et al., 2014) from a continuous Rhaetian-Hettangian section near Levanto, Peru, provide an opportunity to understand the duration of these carbon cycle disruptions, and ammonite biostratigraphy allows comparison to other sections. We measured % organic carbon and % inorganic carbon along with δ13Corganic and δ13Ccarbonate at the section near Levanto. We find a series of δ13Corganic excursions that are similar to those found in other Triassic-Jurassic successions, both from the Tethyan (St. Audrie's Bay, UK) and Panthalassic oceans (Kennecott Point, CAN), pointing to the global extent of these changes. At Levanto, we can identify a brief, initial positive carbon isotope excursion followed first by a sharp negative excursion that coincides with the last appearance of Triassic ammonites, and then a more extended positive carbon isotope excursion that extends into the initial Jurassic recovery. Using the ash bed dates from Levanto, we are able for the first time to estimate robustly the duration of each carbon isotope excursion across the Triassic-Jurassic interval. These estimates of durations aid in our understanding of timing and causes of carbon cycle perturbations associated with the emplacement of CAMP and its relation to mass extinction.

  7. The time has changed: Middle Triassic climate changes revealed by carbon isotopes

    NASA Astrophysics Data System (ADS)

    Schmid, S.; Worden, R.; Fisher, Q.

    2003-04-01

    The Middle Triassic stratigraphy in Europe can be subdivided into a marine section of the Germanic and Paris Basin and a continental red-bed succession of Western Europe (Irish Basin, Wessex Basin). The link between the marine and continental is uncertain due to a lack of biostratigraphic information but recent palaeomagnetic studies have given a better understanding of the two environments (Hounslow et. al, 2001). In this study we have produced geochemical evidence which emphasize the implications of the palaeomagnetic data. We show that the marine and continental strata can be correlated using carbon isotopes. Throughout Europe the Middle Triassic is characterized by limestone deposits of the Muschelkalk Formation that contain evidence of a hiatus in sedimentation due to sea-level fall in the Middle Muschelkalk with the consequent deposition of evaporites. The Sherwood Sandstone Group (SSG) characterizes the Middle Triassic of Western Europe. The SSG is dominated by fluvial deposits with intercalated floodplain deposits, sand-flats and playas, which are penetrated by dolocretes and calcretes. The abundance of fluvial channels and sandflats are dependent on the fluvial activity and the water table height. In both depositional environments water plays a major role in the type of sediment. The volume of water is controlled by the prevalent climate. Climate signals are stored in carbon isotopes in both the marine Muschelkalk and the continental SSG. Carbon isotopes from the SSG from the Corrib Field, Slyne Basin, west of Ireland and from the Muschelkalk of the Germanic Basin have thus been interpreted in terms of climate change linked to stratigraphy. The continental sediments show a distinct positive carbon isotope excursion (taken from dolocretes), which is interpreted to present a more arid climate. In contrast the marine limestones exhibit a negative carbon isotopes excursion from a sea level low stand for the same time interval. The plot of both carbon isotopes

  8. Mercury anomalies and the timing of biotic recovery following the end-Triassic mass extinction.

    PubMed

    Thibodeau, Alyson M; Ritterbush, Kathleen; Yager, Joyce A; West, A Joshua; Ibarra, Yadira; Bottjer, David J; Berelson, William M; Bergquist, Bridget A; Corsetti, Frank A

    2016-01-01

    The end-Triassic mass extinction overlapped with the eruption of the Central Atlantic Magmatic Province (CAMP), and release of CO2 and other volcanic volatiles has been implicated in the extinction. However, the timing of marine biotic recovery versus CAMP eruptions remains uncertain. Here we use Hg concentrations and isotopes as indicators of CAMP volcanism in continental shelf sediments, the primary archive of faunal data. In Triassic-Jurassic strata, Muller Canyon, Nevada, Hg levels rise in the extinction interval, peak before the appearance of the first Jurassic ammonite, remain above background in association with a depauperate fauna, and fall to pre-extinction levels during significant pelagic and benthic faunal recovery. Hg isotopes display no significant mass independent fractionation within the extinction and depauperate intervals, consistent with a volcanic origin for the Hg. The Hg and palaeontological evidence from the same archive indicate that significant biotic recovery did not begin until CAMP eruptions ceased. PMID:27048776

  9. Mercury anomalies and the timing of biotic recovery following the end-Triassic mass extinction

    NASA Astrophysics Data System (ADS)

    Thibodeau, Alyson M.; Ritterbush, Kathleen; Yager, Joyce A.; West, A. Joshua; Ibarra, Yadira; Bottjer, David J.; Berelson, William M.; Bergquist, Bridget A.; Corsetti, Frank A.

    2016-04-01

    The end-Triassic mass extinction overlapped with the eruption of the Central Atlantic Magmatic Province (CAMP), and release of CO2 and other volcanic volatiles has been implicated in the extinction. However, the timing of marine biotic recovery versus CAMP eruptions remains uncertain. Here we use Hg concentrations and isotopes as indicators of CAMP volcanism in continental shelf sediments, the primary archive of faunal data. In Triassic-Jurassic strata, Muller Canyon, Nevada, Hg levels rise in the extinction interval, peak before the appearance of the first Jurassic ammonite, remain above background in association with a depauperate fauna, and fall to pre-extinction levels during significant pelagic and benthic faunal recovery. Hg isotopes display no significant mass independent fractionation within the extinction and depauperate intervals, consistent with a volcanic origin for the Hg. The Hg and palaeontological evidence from the same archive indicate that significant biotic recovery did not begin until CAMP eruptions ceased.

  10. High precision time calibration of the Permo-Triassic boundary mass extinction by U-Pb geochronology

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    U-Pb dating using Chemical Abrasion, Isotope Dilution Thermal Ionization Mass Spectrometry (CA-ID-TIMS) is the analytical method of choice for geochronologists, who are seeking highest temporal resolution and a high degree of accuracy for single grains of zircon. The use of double-isotope tracer solutions, cross-calibrated and assessed in different EARTHTIME labs, coinciding with the reassessment of the uranium decay constants and further improvements in ion counting technology led to unprecedented precision better than 0.1% for single grain, and 0.05% for population ages, respectively. These analytical innovations now allow calibrating magmatic and biological timescales at resolution adequate for both groups of processes. To construct a revised and high resolution calibrated time scale for the Permian-Triassic boundary (PTB) we use (i) high-precision U-Pb zircon age determinations of a unique succession of volcanic ash beds interbedded with shallow to deep water fossiliferous sediments in the Nanpanjiang Basin (South China) combined with (ii) accurate quantitative biochronology based on ammonoids and conodonts and (iii) carbon isotope excursions across the PTB. Using these alignments allows (i) positioning the PTB in different depositional environments and (ii) solving age/stratigraphic contradictions generated by the index, water depth-controlled 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. Besides the general improvement of the radio-isotopic calibration of the PTB at the ±100 ka level, this will also lead to a better understanding of cause and effect relations involved in this mass extinction.

  11. Mercury anomalies and the timing of biotic recovery following the end-Triassic mass extinction

    PubMed Central

    Thibodeau, Alyson M.; Ritterbush, Kathleen; Yager, Joyce A.; West, A. Joshua; Ibarra, Yadira; Bottjer, David J.; Berelson, William M.; Bergquist, Bridget A.; Corsetti, Frank A.

    2016-01-01

    The end-Triassic mass extinction overlapped with the eruption of the Central Atlantic Magmatic Province (CAMP), and release of CO2 and other volcanic volatiles has been implicated in the extinction. However, the timing of marine biotic recovery versus CAMP eruptions remains uncertain. Here we use Hg concentrations and isotopes as indicators of CAMP volcanism in continental shelf sediments, the primary archive of faunal data. In Triassic–Jurassic strata, Muller Canyon, Nevada, Hg levels rise in the extinction interval, peak before the appearance of the first Jurassic ammonite, remain above background in association with a depauperate fauna, and fall to pre-extinction levels during significant pelagic and benthic faunal recovery. Hg isotopes display no significant mass independent fractionation within the extinction and depauperate intervals, consistent with a volcanic origin for the Hg. The Hg and palaeontological evidence from the same archive indicate that significant biotic recovery did not begin until CAMP eruptions ceased. PMID:27048776

  12. 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

  13. Comparison of meter-scale carbonate cycles in Hungarian Late Triassic carbonates with Triassic Italian Alpine and US rift basin deposits

    SciTech Connect

    Haas, J. ); Balog, A.; Read, J.F. )

    1994-03-01

    Triassic-Jurassic rift basins in the eastern US record an excellent record of high frequency climate change dominated by roughly 25, 44, 100 and 400 k.y. Milankovitch climate cycles reflecting continuous sedimentation in these lacustrine basins (Olsen, 1986). Similarly, Goldhammer et al. (1990) showed a well developed record from a Mid-Triassic carbonate platform from the italian alps dominated by precessional (20 k.y.) and subordinate 100 k.y. eccentricity cycles, however, relatively complete cyclic records with bundling of 5 precessional cycles per eccentricity cycle occurred only during long term low-stand or high-stand when accommodation allowed all beats to be recorded. Similarly, Late Triassic off-shelf facies in the Alps show a strong Milankovitch climate forcing in the Triassic, the authors examined the large Late Triassic carbonate platform in Hungary to attempt to determine how well this large shallow marine platform recorded high frequency sea level changes driven by Milankovitch orbital forcing. A combination of 2 km of detailed logs of cores and outcrops provided a data base.

  14. Teaching about time by understanding Geologic Time Scales: The Geological Society of America Geologic Time Scale and its history

    NASA Astrophysics Data System (ADS)

    Geissman, J. W.; Walker, J. D.

    2012-12-01

    Geologic time scales, of one form or another, are used in most undergraduate geosciences courses, even including introductory physical geology or equivalent. However, satisfactory discussions of how geologic time scales originated, and how they have evolved to modern versions, are far too often conveniently or inconveniently left out of classroom discussions. Yet it is these kinds of discussions that have the potential of solidifying student appreciation of deep time and rates of geologic processes. We use the history and development of the Geological Society of America Geologic Time Scale, which reflects major developments in the fields of stratigraphy, geochronology, magnetic polarity stratigraphy, astrochronology, and chemostratigraphy, as a focus of how specific details of time scales can be used to teach about time. Advances in all of these fields have allowed many parts of the time scale to be calibrated to precisions approaching less than 0.05 %. Notable time intervals for which collaborative, multifaceted efforts have led to dramatic improvements in our understanding of the character and temporal resolution of key evolutionary events, in both marine and terrestrial environments, include the Triassic-Jurassic, Permo-Triassic, and Neoproterozoic-Phanerozoic boundaries (or transitions). Many of the details, but certainly not all, can be incorporated in discussions of how we know about geologic time in the classroom. For example, we presently understand that both the end-Permian ecological crisis and the biostratigraphic Permian-Triassic boundary, as calibrated by conodonts, lie within a ca. 700 ka long normal polarity chron. The reverse to normal polarity transition at the beginning of this chron is ca. 100 ka earlier than the ecological crisis and thus slightly older than the current estimate, based on high precision U-Pb zircon age determinations, of ca. 252.4 Ma for the Permian-Triassic boundary. This polarity transition occurred during the early part of

  15. Timing is everything: ecological vs. evolutionary pacing of Triassic-Jurassic carbon cycle disruptions

    NASA Astrophysics Data System (ADS)

    Whiteside, J. H.; Olsen, P. E.; Eglinton, T. I.

    2007-12-01

    Eruption of Earth's largest flood basalt, the Central Atlantic Magmatic Province (CAMP) has been proposed as the trigger for a major carbon cycle disruption at the Triassic-Jurassic mass extinction interval at ~201 Ma. Inferred from negative excursions in the carbon isotopic composition (δ13C) of carbonate and organic matter, this perturbation has been linked to massive dissociation of isotopically light, methane-rich gas hydrates caused by volcanogenic CO2-induced global warming. However, both the sequence and duration of the CAMP eruptions relative to the carbon cycle perturbation remain circumstantial and indirect, because the data have been from stratigraphic sections far from the flood basalts and without accumulation rate constraints. Here we use a record of atmospheric (δ13C) from specific molecules (nC25 - nC32 n-alkanes) diagnostic of terrestrial plant leaf waxes from astronomically-paced cyclical lacustrine strata in which CAMP flood basalts are interbedded to directly examine the relationship between the (δ13C) excursions and their durations. We show that the flood basalts postdate the abrupt start of a ~400 ky negative excursion coincident with the initiation of the mass extinction event, but predate a protracted 1.5 m.y. negative excursion. Based on a modified BLAG carbon cycle model, the timing and long durations of our (δ13C) excursions are incompatible with CAMP-triggered gas hydrate release. Instead, we suggest that the (δ13C) pattern is more consistent with a catastrophically-triggered functional reorganization of the biosphere, part of which involved the ascent of dinosaurs to ecological dominance, playing out over evolutionary time.

  16. Position of the Triassic-Jurassic boundary and timing of the end-Triassic extinctions on land: Data from the Moenave Formation on the southern Colorado Plateau, USA

    USGS Publications Warehouse

    Lucas, S.G.; Tanner, L.H.; Donohoo-Hurley, L.; Geissman, J.W.; Kozur, H.W.; Heckert, A.B.; Weems, R.E.

    2011-01-01

    Strata of the Moenave Formation on and adjacent to the southern Colorado Plateau in Utah-Arizona, U.S.A., represent one of the best known and most stratigraphically continuous, complete and fossiliferous terrestrial sections across the Triassic-Jurassic boundary. We present a synthesis of new biostratigraphic and magnetostratigraphic data collected from across the Moenave Formation outcrop belt, which extends from the St. George area in southwestern Utah to the Tuba City area in northern Arizona. These data include palynomorphs, conchostracans and vertebrate fossils (including footprints) and a composite polarity record based on four overlapping magnetostratigraphic sections. Placement of the Triassic-Jurassic boundary in strata of the Moenave Formation has long been imprecise and debatable, but these new data (especially the conchostracans) allow us to place the Triassic-Jurassic boundary relatively precisely in the middle part of the Whitmore Point Member of the Moenave Formation, stratigraphically well above the highest occurrence of crurotarsan body fossils or footprints. Correlation to marine sections based on this placement indicates that major terrestrial vertebrate extinctions preceded marine extinctions across the Triassic-Jurassic boundary and therefore were likely unrelated to the Central Atlantic Magmatic Province (CAMP) volcanism. ?? 2011 Elsevier B.V.

  17. 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

    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.

  18. 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.

  19. Timing and magnitude of tetrapod extinctions across the Permo-Triassic boundary

    NASA Astrophysics Data System (ADS)

    Lucas, Spencer G.

    2009-11-01

    A review of the tetrapod (amphibian and amniote) record across the Permo-Triassic boundary (PTB) indicates a global evolutionary turnover of tetrapods close to the PTB. There is also a within-Guadalupian tetrapod extinction here called the dinocephalian extinction event, probably of global extent. The dinocephalian extinction event is a late Wordian or early Capitanian extinction based on biostratigraphic data and magnetostratigraphy (the extinction precedes the Illawara reversal), so it is not synchronous with the end-Guadalupian marine extinction. The Russian PTB section documents two tetrapod extinction events, one just before the dinocephalian extinction event and the other at the base of the Lystrosaurus assemblage. However, generic diversity across the latter extinction remains essentially the same despite a total evolutionary turnover of tetrapod genera. The Chinese and South African sections document the stratigraphic overlap of Dicynodon and Lystrosaurus. In the Karoo basin, the lowest occurrence of Lystrosaurus is in a stratigraphic interval of reversed magnetic polarity, which indicates it predates the marine-defined PTB, so, as previously suggested by some workers, the lowest occurrence of Lystrosaurus cannot be used to identify the PTB in nonmarine strata. Correlation of the marine PTB section at Meishan, southern China, to the Karoo basin based primarily on magnetostratigraphy indicates that the main marine extinction preceded the PTB tetrapod extinction event. The ecological severity of the PTB tetrapod extinction event has generally been overstated, and the major change in tetrapod assemblages that took place across the PTB was the prolonged and complex "replacement" of therapsids by archosaurs that began before the end of the Permian and was not complete until well into the Triassic. The tetrapod extinctions are not synchronous with the major marine extinctions at the end of the Guadalupian and just before the end of the Permian, so the idea of

  20. Paleomagnetism of the Upper Triassic rocks from south of the Ailaoshan Suture and the timing of the amalgamation between the South China and the Indochina Blocks

    NASA Astrophysics Data System (ADS)

    Huang, Kainian; Opdyke, Neil D.

    2016-04-01

    A high temperature remanence with thermally-discrete unblocking temperature spectra has been isolated from the redbed samples of the Upper Triassic Yiwanshui Formation collected from south of the Ailaoshan Suture in southern Yunnan Province of China. Two groups of directions were observed: the tilt-corrected mean is D/I = 141.4°/31.2° with α95 = 13.0° based on 12 sites for the first group, and D/I = 207.5°/4.9° with α95 = 16.0° based on 5 sites for the second group. The second group of directions was derived from massively bedded rocks with large uncertainties in determination of the paleo-horizontal and is thus deemed inaccurate. The first group of directions passes the foldtest with dual polarity, and is consistent with results previously reported from the same type section, and probably represents primary magnetization of the rock formation. Comparison with the Triassic paleomagnetic poles for the Baoshan Terrane and the South China Block indicates that the Simao and the Baoshan terranes were probably already amalgamated by late Triassic times but the coalescence between them and the South China Block may have not been completed until near the end of the Triassic.

  1. Time Scales: Terrestrial

    NASA Astrophysics Data System (ADS)

    Petit, G.; Murdin, P.

    2000-11-01

    Terrestrial time is at present derived from atomic clocks. The SI second, the unit of time of the international system of units, has been defined since 1967 in terms of a hyperfine transition of the cesium atom and the best primary frequency standards now realize it with a relative uncertainty of a few parts in 1015, which makes it the most accurately measurable physical quantity. INTERNATIONAL A...

  2. 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.

  3. Three-dimensional accommodation analysis of the Triassic in the Paris Basin: a new approach in unravelling the basin evolution with time

    NASA Astrophysics Data System (ADS)

    Goggin, Valerie; Jacquin, Thierry; Gaulier, Jean Michel

    1997-12-01

    The mechanisms governing the development of the Paris Basin throughout the Triassic are regarded as being the result of superimposed and successive processes. In this study, the Triassic succession of the Paris Basin was re-interpreted in a sequence stratigraphic context, using essentially wireline log data. From this, a series of isopach maps, lithofacies maps and palaeobathymetric maps was produced for each sequence. Three-dimensional accommodation analysis was then carried out sequence by sequence, over the entire basin to produce a precise, detailed accommodation history for the entire Triassic succession. Previous studies have proposed that the Triassic was deposited during a rift period in a transtensional stress regime, with the formation of a trough superposed onto three fault systems derived from the Variscan structural framework. In this study, Scythian to Ladinian sediments (Buntsandstein and Muschelkalk) record the stress regime that prevailed over much of NW Europe. The basin architecture at this time is in continuity with the neighbouring Germanic Basin. Our three-dimensional accommodation modelling shows that the stress regime changed during the Carnian and the late Norian (Keuper). The Carnian events are marked by (1) the creation of a large depocentre infilled with halite, and (2) a northwest migration of this depocentre during the mid-late Carnian along with deposition of the Grès-à-Roseaux, an extensive fluvial deposit. This documents renewed strike-slip movement along the Bray fault. The Norian events involved major tectonic uplift on the basin margins, producting fan delta progradation into the basin. Rotation of the previous depocentre axis occurs on the downthrown side of the Bray fault. This may be viewed as a consequence of sinistral strike-slip displacement along the Bray fault, forming a local transpressive stress regime. The following Liassic cycle commenced with the Rhaetic sequences and illustrates a complete change in the stress

  4. The Triassic-Jurassic boundary in eastern North America

    NASA Technical Reports Server (NTRS)

    Olsen, P. E.; Comet, B.

    1988-01-01

    Rift basins of the Atlantic passive margin in eastern North America are filled with thousands of meters of continental rocks termed the Newark Supergroup which provide an unprecedented opportunity to examine the fine scale structure of the Triassic-Jurassic mass extinction in continental environments. Time control, vital to the understanding of the mechanisms behind mass extinctions, is provided by lake-level cycles apparently controlled by orbitally induced climate change allowing resolution at the less than 21,000 year level. Correlation with other provinces is provided by a developing high resolution magnetostratigraphy and palynologically-based biostratigraphy. A large number of at least local vertebrate and palynomorph extinctions are concentrated around the boundary with survivors constituting the earliest Jurassic assemblages, apparently without the introduction of new taxa. The palynofloral transition is marked by the dramatic elimination of a relatively high diversity Triassic pollen assemblage with the survivors making up a Jurassic assemblage of very low diversity overwhelmingly dominated by Corollina. Based principally on palynological correlations, the hypothesis that these continental taxonomic transitions were synchronous with the massive Triassic-Jurassic marine extinctions is strongly corroborated. An extremely rapid, perhaps catastrophic, taxonomic turnover at the Triassic-Jurassic boundary, synchronous in continental and marine realms is hypothesized and discussed.

  5. Relation of Middle and Late Triassic strata of N-C Nevada to contemporaneous strata of southern Nevada and Utah

    SciTech Connect

    Elison, M.W.

    1993-04-01

    Middle and Late Triassic shelf strata in north-central Nevada comprising dominantly carbonate rocks of the Star Peak Group and overlying siliciclastic and carbonate rocks are overlain tectonically by predominantly siliciclastic basinal strata. Late Triassic slope strata are preserved in the East and Humboldt Ranges. At present, these Triassic rocks are separated from contemporaneous deposits of Utah by roughly 300 km over which time-equivalent ( ) strata are limited to a small, isolated outcrop near Currie, NV. Mesozoic and Cenozoic tectonics and widespread absence of Triassic rocks immediately to the east complicate the relation between the north-central Nevada section and Triassic rocks of southern Nevada and Utah. The gap in Triassic rocks may have resulted from erosion of intervening strata or from tectonic separation of originally contiguous stratal sequences. Some depositional facies of the shelf uniformly cover the preserved outcrop area and do not constrain the scale of the depositional system. Where facies variations are present, they suggest sediment sources to the east and north and deeper water to the west. Facies patterns, however, were influenced by local tectonics and changes in sediment source and supply. Late Triassic strata of N-C Nevada probably are the shallow-marine equivalents of fluvial and lacustrine rocks to the east. Local tectonics and changes in sediment influx require caution regarding interpretation of the original proximity of preserved stratal sequences.

  6. The timing of final closure along the Changchun-Yanji suture zone: Constraints from detrital zircon U-Pb dating of the Triassic Dajianggang Formation, NE China

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Zhou, Jian-Bo; Wilde, Simon A.; Zhang, Xing-Zhou; Ren, Shou-Mai

    2016-09-01

    The Dajianggang Formation is located in the Changchun-Yanji suture zone of central Jilin Province and unconformably overlies the Changchun-Yanji Accretionary Complex (CYAC), which is a mélange resulting from subduction of the Jiamusi-Khanka Block (JKB) beneath the North China Craton (NCC). LA-MC-ICP-MS U-Pb dating of detrital zircon from four samples of the formation yields ages of 2516 to 216 Ma. Zircons with U-Pb ages at 2516-2501 Ma and 1897-1832 Ma indicate a provenance from Precambrian basement rocks of the NCC. The 525-482 Ma ages indicate a provenance from metamorphic rocks of Late Pan-African age in the JKB that have a tectonic affinity to the Central Asian Orogenic Belt (CAOB). Zircon grains with ages of 383-314 Ma and 275-250 Ma were likely derived from the underlying CYAC. The youngest population has a peak age of ca. 225 Ma, which together with Late Triassic fossils, suggests that deposition of the Dajianggang Formation was Late Triassic or younger. This result supports the view that the final collision of the JKB and NCC along the Changchun-Yanji suture took place before the Late Triassic. Furthermore, this closure time is at least 10-20 Ma later than closure along the Solonker-Xar Moron-Changchun suture in the Late Permian. We thus establish that the Changchun-Yanji suture is not related to the collision between the Siberia Craton (SC) and the NCC but was instead related to the Paleo-Pacific plate subduction. Consequently, the Changchun-Yanji suture is not the eastward extension of the Solonker-Xar Moron-Changchun suture as previously considered, but the southern margin of the Jilin-Heilongjiang high-pressure metamorphic belt (Ji-Hei HP belt), and resulted from westward subduction of the Paleo-Pacific Ocean. Thus, the Late Triassic marked the switch in subduction from the Paleo-Asian Ocean to the Paleo-Pacific Ocean in NE China.

  7. Permian-Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution.

    PubMed

    Romano, Carlo; Koot, Martha B; Kogan, Ilja; Brayard, Arnaud; Minikh, Alla V; Brinkmann, Winand; Bucher, Hugo; Kriwet, Jürgen

    2016-02-01

    The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian-Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian-Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, 'Palaeopterygii', 'Subholostei', Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end-Guadalupian crisis is not evident from our data, but 'palaeopterygians' experienced a significant body size increase across the Guadalupian-Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian-Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians, 'palaeopterygians', 'subholosteans') and a second one during the Middle Triassic ('subholosteans', neopterygians). The origination of new, small taxa predominantly among these groups during the Middle Triassic event caused a

  8. Early Triassic geologic history of northeastern Nevada

    SciTech Connect

    Paull, R.K.; Paull, R.A.

    1986-08-01

    Conodont biostratigraphic and lithostratigraphic studies of Lower Triassic rocks in northeastern Elko County, Nevada, and adjacent parts of Idaho and Utah provide new information about regional geologic history. A sequential summary of Early Triassic events in this area follows: (1) rapid transgression of the Griesbachian sea to limiting barriers on the south (Oquirrh-Uinta axis) and west (Humboldt highland.). (2) Although the initial Triassic transgression may have persisted farther south and west than present-day evidence indicates, a period of progradation during the Dienerian limited marine sedimentation to northeastern-most Nevada and adjacent states. (3) In Smithian time, a widespread transgression spilled south and west over the earliest Triassic basin margin. (4) The southward flood is characterized by locally spectacular basal conglomerates followed by shallow marine deposits of the Thaynes Formation. (5) The transgression to the west was facilitated by tectonic removal of the restrictive barrier during the Smithian. This resulted in a slope-basin environment that accumulated a thick sequence of shale and calcareous siltstone with interbeds of turbidite conglomerates, olistostromes, and exotic blocks derived from Permian formations in northern Nevada or adjacent Idaho. (6) During a regional progradation in early Spathian time, marine conditions persisted in northeastern Nevada. (7) A final depositional episode is documented by the progressive westward spread of carbonate rocks of the Thaynes Formation. (8) Withdrawal of Triassic seas from northeast Nevada occurred post-latest Early Triassic, since a carbonate sequence of more than 300 m overlies the youngest dated interval.

  9. Time scales in cognitive neuroscience

    PubMed Central

    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

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

    NASA Astrophysics Data System (ADS)

    Bourquin, Sylvie; Peron, Samuel; Durand, Marc

    2006-05-01

    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 studies are required to realise sequence stratigraphy correlations and establish comparisons with others parts of the Germanic Basin. In a first step, we use well-log data analyses to characterise the electrofacies associations in the Triassic and then define the well-log signatures of each formation. In a second step, the characterisation and recognition of genetic sequences and their stacking pattern allow us to define seven minor cycles integrated into two major cycles. Finally, the quantification of the lithologies at different stages of basin evolution leads to the reconstruction of paleoenvironmental maps to illustrate facies evolution through space and time. A comparison with cycles defined in the Germanic Basin allows us to propose correlations of the Lower Triassic on either side of the Rhine Graben and leads to a discussion of the evolution of fluvial systems through time and space. During the Scythian, the fluvial style is characterised by braided fluvial systems evolving laterally into lake deposits towards the central part of the Germanic Basin. During this stage, the basin was a huge depression with very few marine connections in its extreme eastern part. The stratigraphic cycles represent rhythmic fluctuations in relative lake level that could be attributed to sediment supply and/or lake level variations in an arid setting. Four minor stratigraphic cycles are observed that are integrated within a single major stratigraphic cycle. During the period of the stratigraphic base-level rise of the major cycle, a maximum of 233 m of sediment would represent a duration of sedimentation in the Paris Basin of at least 1.8 m

  11. Late Triassic paleomagnetic result from the Baoshan Terrane, West Yunnan of China: Implication for orientation of the East Paleotethys suture zone and timing of the Sibumasu-Indochina collision

    NASA Astrophysics Data System (ADS)

    Zhao, Jie; Huang, Baochun; Yan, Yonggang; Zhang, Donghai

    2015-11-01

    In order to better understand the paleogeographic position of the Baoshan Terrane in the northernmost part of the Sibumasu Block during formation of the Pangea supercontinent, a paleomagnetic study has been conducted on Late Triassic basaltic lavas from the southern part of the Baoshan Terrane in the West Yunnan region of Southwest China. Following detailed rock magnetic investigations and progressive thermal demagnetization, stable characteristic remanent magnetizations (ChRMs) were successfully isolated from Late Triassic Niuhetang lava flows. The ChRMs are of dual polarity and pass fold and reversal tests with magnetic carriers dominated by magnetite and subordinate oxidation-induced hematite; we thus interpret them as a primary remanence. This new paleomagnetic result indicates that the Baoshan Terrane was located at low paleolatitudes of ∼15°N in the Northern Hemisphere during Late Triassic times. Together with available paleomagnetic data from the Baoshan Terrane and surrounding areas, a wider paleomagnetic comparison supports the view that the East Paleotethys Ocean separated the Sibumasu and Indochina blocks and closed no later than Late Triassic times. We argue that the currently approximately north-to-south directed Changning-Menglian suture zone is very likely to have been oriented nearly east-to-west at the time of the Sibumasu-Indochina collision.

  12. 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

  13. Synchroneity of climatic change and extinctions in the Late Triassic

    NASA Astrophysics Data System (ADS)

    Simms, Michael J.; Ruffell, Alastair H.

    1989-03-01

    Although the Late Triassic was a time of widespread aridity, evidence exists for a significant increase in rainfall during the middle to late Carnian. Upper Triassic playa-lake sediments were interrupted by late Carnian fluviatile sandstones with erosive bases and high kao-linite/illite ratios. There was also an increase in the clastic component of marine sequences during this interval. Middle and upper Carnian marine carbonates show an extreme depletion in δ13C values, consistent with increased fresh-water influx. Large-scale karstic phenomena in limestone areas subaerially exposed during the Late Triassic are a further indication of increased rainfall. Important faunal and floral changes occurred during the Carnian-Norian interval; marine invertebrate turnover was greatest at the lower/middle Carnian boundary, and terrestrial extinctions were concentrated at the Carnian/Norian boundary. The cause of this Carnian pluvial episode may have been related to the rifting of Pangea, through disruption of atmospheric and oceanic circulation patterns, eustatic changes, or the effects of volcanism associated with rifting. A change in surface ocean temperature, salinity or pH, or habitat loss may have caused the decline of many shallow-marine invertebrates at the start of the middle Carnian; a return to arid conditions at the Carnian/Norian boundary would account for the turnover among terrestrial vertebrates and plants.

  14. The history of the Arabian platform evolution in the Late Permian and Triassic

    SciTech Connect

    Bebeshev, I.I.

    1995-03-01

    On the basis of comprehensive investigations of the Upper Permian and Triassic sequences of the Arabian platform, three stages were recognized, corresponding to distinct time intervals. The first stage corresponds to the Latest Permian-Early Triassic, the second - to the Early-Middle Triassic, the third - to the Late Triassic. Special maps were plotted for the second and third stages, reflecting major paleogeographic and paleotectonic events. An effort was made to test the oil potential of the sequences.

  15. The early Cretaceous orogen-scale Dabieshan metamorphic core complex: implications for extensional collapse of the Triassic HP-UHP orogenic belt in east-central China

    NASA Astrophysics Data System (ADS)

    Ji, Wenbin; Lin, Wei; Faure, Michel; Shi, Yonghong; Wang, Qingchen

    2016-03-01

    The Dabieshan massif is famous as a portion of the world's largest HP-UHP metamorphic belt in east-central China that was built by the Triassic North-South China collision. The central domain of the Dabieshan massif is occupied by a huge migmatite-cored dome [i.e., the central Dabieshan dome (CDD)]. Origin of this domal structure remains controversial. Synthesizing previous and our new structural and geochronological data, we define the Cretaceous Dabieshan as an orogen-scale metamorphic core complex (MCC) with a multistage history. Onset of lithospheric extension in the Dabieshan area occurred as early as the commencement of crustal anatexis at the earliest Cretaceous (ca. 145 Ma), which was followed by primary (early-stage) detachment during 142-130 Ma. The central Dabieshan complex in the footwall and surrounding detachment faults recorded a consistently top-to-the-NW shearing. It is thus inferred that the primary detachment was initiated from a flat-lying detachment zone at the middle crust level. Removal of the orogenic root by delamination at ca. 130 Ma came into the extensional climax, and subsequently isostatic rebound resulted in rapid doming. Along with exhumation of the footwall, the mid-crustal detachment zone had been warped as shear zones around the CDD. After 120 Ma, the detachment system probably experienced a migration accommodated to the crustal adjustment, which led to secondary (late-stage) detachment with localized ductile shearing at ca. 110 Ma. The migmatite-gneiss with HP/UHP relicts in the CDD (i.e., the central Dabieshan complex) was product of the Cretaceous crustal anatexis that consumed the deep-seated part of the HP-UHP slices and the underlying para-autochthonous basement. Compared with the contemporaneous MCCs widely developed along the eastern margin of the Eurasian continent, we proposed that occurrence of the Dabieshan MCC shares the same tectonic setting as the "destruction of the North China craton". However, geodynamic trigger

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

    NASA Astrophysics Data System (ADS)

    Gradstein, Felix M.

    2010-05-01

    , 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.

  17. 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 δ34S-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.

  18. The Sail-Backed Reptile Ctenosauriscus from the Latest Early Triassic of Germany and the Timing and Biogeography of the Early Archosaur Radiation

    PubMed Central

    Butler, Richard J.; Brusatte, Stephen L.; Reich, Mike; Nesbitt, Sterling J.; Schoch, Rainer R.; Hornung, Jahn J.

    2011-01-01

    Background Archosaurs (birds, crocodilians and their extinct relatives including dinosaurs) dominated Mesozoic continental ecosystems from the Late Triassic onwards, and still form a major component of modern ecosystems (>10,000 species). The earliest diverse archosaur faunal assemblages are known from the Middle Triassic (c. 244 Ma), implying that the archosaur radiation began in the Early Triassic (252.3–247.2 Ma). Understanding of this radiation is currently limited by the poor early fossil record of the group in terms of skeletal remains. Methodology/Principal Findings We redescribe the anatomy and stratigraphic position of the type specimen of Ctenosauriscus koeneni (Huene), a sail-backed reptile from the Early Triassic (late Olenekian) Solling Formation of northern Germany that potentially represents the oldest known archosaur. We critically discuss previous biomechanical work on the ‘sail’ of Ctenosauriscus, which is formed by a series of elongated neural spines. In addition, we describe Ctenosauriscus-like postcranial material from the earliest Middle Triassic (early Anisian) Röt Formation of Waldhaus, southwestern Germany. Finally, we review the spatial and temporal distribution of the earliest archosaur fossils and their implications for understanding the dynamics of the archosaur radiation. Conclusions/Significance Comprehensive numerical phylogenetic analyses demonstrate that both Ctenosauriscus and the Waldhaus taxon are members of a monophyletic grouping of poposauroid archosaurs, Ctenosauriscidae, characterised by greatly elongated neural spines in the posterior cervical to anterior caudal vertebrae. The earliest archosaurs, including Ctenosauriscus, appear in the body fossil record just prior to the Olenekian/Anisian boundary (c. 248 Ma), less than 5 million years after the Permian–Triassic mass extinction. These earliest archosaur assemblages are dominated by ctenosauriscids, which were broadly distributed across northern Pangea and which

  19. 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.

  20. Stability of Rasch Scales over Time

    ERIC Educational Resources Information Center

    Taylor, Catherine S.; Lee, Yoonsun

    2010-01-01

    Item response theory (IRT) methods are generally used to create score scales for large-scale tests. Research has shown that IRT scales are stable across groups and over time. Most studies have focused on items that are dichotomously scored. Now Rasch and other IRT models are used to create scales for tests that include polytomously scored items.…

  1. Introduction to the time scale problem

    SciTech Connect

    Voter, A. F.

    2002-01-01

    As motivation for the symposium on extended-scale atomistic methods, I briefly discuss the time scale problem that plagues molecular dynamics simulations, some promising recent developments for circumventing the problem, and some remaining challenges.

  2. How severe is the modern biotic crisis?—A comparison of global change and biotic crisis between Permian-Triassic transition and modern times

    NASA Astrophysics Data System (ADS)

    Yin, Hongfu; He, Weihong; Xie, Shucheng

    2011-03-01

    A comparison of the modern condition with the Permian-Triassic Boundary (PTB) times was made to estimate how severe the modern biotic crisis is. About the global changes, the two periods are correlative in carbon dioxide concentration and carbon isotope negative excursion, UV strengthening, temperature increase, ocean acidification, and weathering enhancement. The following tendencies of biotic crises are also correlative: acceleration of extinction rates accompanied by parabolic curve of extinction with a turning interval representing the critical crisis; decline of the three main ecosystems: reefs, tropical rain forests and marine phytoplankton. It is also interesting to note that certain leading organism in both periods undergo accelerated evolution during the crisis. The comparison shows that the modern crisis is about at the turning point from decline to decimation. The extinction curve is now parabolic, and the extinction rate has been accelerated, but the decimation is not yet in real. This is also justified by the modern situation of the three main ecosystems. Modern biotic decline may worsen into decimation and mass extinction but may also get better and recover to ordinary evolution. Since human activities are the main cause of the deterioration of environments and organisms, mankind should be responsible and able to strive for the recovery of the crisis. For the future of mankind, Homo sapiens may become extinct, i.e., disappear without leaving descendants, or evolve into a new and more advanced species, i.e., disappear but leave descendants. For a better future, mankind should be conscious of the facing danger and act as a whole to save biodiversity and harmonize with the environments.

  3. Review of time scales. [Universal Time-Ephemeris Time-International Atomic Time

    NASA Technical Reports Server (NTRS)

    Guinot, B.

    1974-01-01

    The basic time scales are presented: International Atomic Time, Universal Time, and Universal Time (Coordinated). These scales must be maintained in order to satisfy specific requirements. It is shown how they are obtained and made available at a very high level of precision.

  4. Kalman plus weights: a time scale algorithm

    NASA Technical Reports Server (NTRS)

    Greenhall, C. A.

    2001-01-01

    KPW is a time scale algorithm that combines Kalman filtering with the basic time scale equation (BTSE). A single Kalman filter that estimates all clocks simultaneously is used to generate the BTSE frequency estimates, while the BTSE weights are inversely proportional to the white FM variances of the clocks. Results from simulated clock ensembles are compared to previous simulation results from other algorithms.

  5. Multiple time scale methods in tokamak magnetohydrodynamics

    SciTech Connect

    Jardin, S.C.

    1984-01-01

    Several methods are discussed for integrating the magnetohydrodynamic (MHD) equations in tokamak systems on other than the fastest time scale. The dynamical grid method for simulating ideal MHD instabilities utilizes a natural nonorthogonal time-dependent coordinate transformation based on the magnetic field lines. The coordinate transformation is chosen to be free of the fast time scale motion itself, and to yield a relatively simple scalar equation for the total pressure, P = p + B/sup 2//2..mu../sub 0/, which can be integrated implicitly to average over the fast time scale oscillations. Two methods are described for the resistive time scale. The zero-mass method uses a reduced set of two-fluid transport equations obtained by expanding in the inverse magnetic Reynolds number, and in the small ratio of perpendicular to parallel mobilities and thermal conductivities. The momentum equation becomes a constraint equation that forces the pressure and magnetic fields and currents to remain in force balance equilibrium as they evolve. The large mass method artificially scales up the ion mass and viscosity, thereby reducing the severe time scale disparity between wavelike and diffusionlike phenomena, but not changing the resistive time scale behavior. Other methods addressing the intermediate time scales are discussed.

  6. Time scale in quasifission reactions

    SciTech Connect

    Back, B.B.; Paul, P.; Nestler, J.

    1995-08-01

    The quasifission process arises from the hindrance of the complete fusion process when heavy-ion beams are used. The strong dissipation in the system tends to prevent fusion and lead the system towards reseparation into two final products of similar mass reminiscent of a fission process. This dissipation slows down the mass transfer and shape transformation and allows for the emission of high energy {gamma}-rays during the process, albeit with a low probability. Giant Dipole {gamma} rays emitted during this time have a characteristic spectral shape and may thus be discerned in the presence of a background of {gamma} rays emitted from the final fission-like fragments. Since the rate of GDR {gamma} emission is very well established, the strength of this component may therefore be used to measure the timescale of the quasifission process. In this experiment we studied the reaction between 368-MeV {sup 58}Ni and a {sup 165}Ho target, where deep inelastic scattering and quasifission processes are dominant. Coincidences between fission fragments (detected in four position-sensitive avalanche detectors) and high energy {gamma} rays (measured in a 10{close_quotes} x 10{close_quotes} actively shielded NaI detector) were registered. Beams were provided by the Stony Brook Superconducting Linac. The {gamma}-ray spectrum associated with deep inelastic scattering events is well reproduced by statistical cooling of projectile and target-like fragments with close to equal initial excitation energy sharing. The y spectrum associated with quasifission events is well described by statistical emission from the fission fragments alone, with only weak evidence for GDR emission from the mono-nucleus. A 1{sigma} limit of t{sub ss} < 11 x 10{sup -21} s is obtained for the mono-nucleus lifetime, which is consistent with the lifetime obtained from quasifission fragment angular distributions. A manuscript was accepted for publication.

  7. Advances in the Geomagnetic Polarity Time Scale--Developments and Integration with the Geologic Time Scale and Future Directions (Invited)

    NASA Astrophysics Data System (ADS)

    Geissman, J. W.

    2013-12-01

    We celebrate the 50th anniversary of the publication of the Vine-Matthews/Morley-Larochelle hypothesis (Vine and Matthews, Nature, 1963, v. 199, #4897, p. 947-949), which integrated marine magnetic anomaly data with a rapidly evolving terrestrial-based geomagnetic polarity time scale (GPTS). The five decades of research since 1963 have witnessed the expansion and refinement of the GPTS, to the point where ages of magnetochron boundaries, in particular in the Cenozoic, can be estimated with uncertainties better than 0.1%. This has come about by integrating high precision geochronology, cyclostratigraphy at different time scales, and magnetic polarity data of increased quality, allowing extension of the GPTS back into the Paleozoic. The definition of a high resolution GPTS across time intervals of major events in Earth history has been of particular interest, as a specific magnetochron boundary correlated across several localities represents a singular global datum. A prime example is the end Permian, when some 80 percent of genus-level extinctions and a range of 75 to 96 percent species- level extinctions took place in the marine environment, depending upon clade. Much our understanding of the Permian-Triassic boundary (PTB) is based on relatively slowly deposited marine sequences in Europe and Asia, yet a growing body of observations from continental sequences demonstrates a similar extinction event and new polarity data from some of these sequences are critical to refining the GPTS across the PTB and testing synchronicity of marine and terrestrial events. The data show that the end-Permian ecological crisis and the conodont calibrated biostratigraphic PTB both followed a key polarity reversal between a short interval (subchron) of reverse polarity to a considerably longer (chron) of normal polarity. Central European Basin strata (continental Permian and epicontinental Triassic) yield high-quality magnetic polarity stratigraphic records (Szurlies et al., 2003

  8. Time-dependent corona models - Scaling laws

    NASA Technical Reports Server (NTRS)

    Korevaar, P.; Martens, P. C. H.

    1989-01-01

    Scaling laws are derived for the one-dimensional time-dependent Euler equations that describe the evolution of a spherically symmetric stellar atmosphere. With these scaling laws the results of the time-dependent calculations by Korevaar (1989) obtained for one star are applicable over the whole Hertzsprung-Russell diagram and even to elliptic galaxies. The scaling is exact for stars with the same M/R-ratio and a good approximation for stars with a different M/R-ratio. The global relaxation oscillation found by Korevaar (1989) is scaled to main sequence stars, a solar coronal hole, cool giants and elliptic galaxies.

  9. 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

  10. Putting scales into evolutionary time: the divergence of major scale insect lineages (Hemiptera) predates the radiation of modern angiosperm hosts.

    PubMed

    Vea, Isabelle M; Grimaldi, David A

    2016-01-01

    The radiation of flowering plants in the mid-Cretaceous transformed landscapes and is widely believed to have fuelled the radiations of major groups of phytophagous insects. An excellent group to test this assertion is the scale insects (Coccomorpha: Hemiptera), with some 8,000 described Recent species and probably the most diverse fossil record of any phytophagous insect group preserved in amber. We used here a total-evidence approach (by tip-dating) employing 174 morphological characters of 73 Recent and 43 fossil taxa (48 families) and DNA sequences of three gene regions, to obtain divergence time estimates and compare the chronology of the most diverse lineage of scale insects, the neococcoid families, with the timing of the main angiosperm radiation. An estimated origin of the Coccomorpha occurred at the beginning of the Triassic, about 245 Ma [228-273], and of the neococcoids 60 million years later [210-165 Ma]. A total-evidence approach allows the integration of extinct scale insects into a phylogenetic framework, resulting in slightly younger median estimates than analyses using Recent taxa, calibrated with fossil ages only. From these estimates, we hypothesise that most major lineages of coccoids shifted from gymnosperms onto angiosperms when the latter became diverse and abundant in the mid- to Late Cretaceous. PMID:27000526

  11. Putting scales into evolutionary time: the divergence of major scale insect lineages (Hemiptera) predates the radiation of modern angiosperm hosts

    PubMed Central

    Vea, Isabelle M.; Grimaldi, David A.

    2016-01-01

    The radiation of flowering plants in the mid-Cretaceous transformed landscapes and is widely believed to have fuelled the radiations of major groups of phytophagous insects. An excellent group to test this assertion is the scale insects (Coccomorpha: Hemiptera), with some 8,000 described Recent species and probably the most diverse fossil record of any phytophagous insect group preserved in amber. We used here a total-evidence approach (by tip-dating) employing 174 morphological characters of 73 Recent and 43 fossil taxa (48 families) and DNA sequences of three gene regions, to obtain divergence time estimates and compare the chronology of the most diverse lineage of scale insects, the neococcoid families, with the timing of the main angiosperm radiation. An estimated origin of the Coccomorpha occurred at the beginning of the Triassic, about 245 Ma [228–273], and of the neococcoids 60 million years later [210–165 Ma]. A total-evidence approach allows the integration of extinct scale insects into a phylogenetic framework, resulting in slightly younger median estimates than analyses using Recent taxa, calibrated with fossil ages only. From these estimates, we hypothesise that most major lineages of coccoids shifted from gymnosperms onto angiosperms when the latter became diverse and abundant in the mid- to Late Cretaceous. PMID:27000526

  12. Astronomical control on climate and vegetation history at the Triassic-Jurassic transition

    NASA Astrophysics Data System (ADS)

    Ruhl, Micha; Bonis, Nina R.; Deenen, Martijn H. L.; Abels, Hemmo A.; Krijgsman, Wout; Kurschner, 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, closely coincides with the onset of intensified volcanic activity in the Central Atlantic Magmatic Province (CAMP), the largest igneous province on earth. The end-Triassic environmental crisis is followed by successive recovery in the early Jurassic Hettangian stage. However, accurate timing of events is poorly constrained. Here we present combined chemical and biological proxy records and field observations, covering the uppermost Triassic and lower Jurassic marine successions of St. Audrie's Bay and East Quantoxhead (UK). A floating astronomical time-scale of ~2.5 Myr has been constructed based on the recognition of ~100-kyr eccentricity cycles. Individual black shale occurrences are interpreted to reflect precession-controlled changes in monsoon intensity. Gaseous CO2 release by the increased volcanic activity strongly enhanced greenhouse warming and likely caused a shift from a diverse gymnosperm vegetation to a monotonous Cheirolepidiaceous conifer vegetation. Vegetation distribution at the Triassic-Jurassic transition was likely influenced by the strong temperature and humidity gradient from the oceans to the interior of Pangea. Vegetation cover was mostly situated in coastal regions, with the inlands being more arid. Strong eccentricity-scale paced increases in pollen concentrations suggest the inland expansion of Cheirolepidiaceous vegetation cover, which is likely caused by intensified monsoon activity. Our palynological data further shows precession-scale paced peaks in spore abundance during the mass extinction interval, suggesting astronomical forcing of the hydrological cycle under extreme climatic conditions.

  13. Triassic tectonics of the Ailaoshan Belt (SW China): Early Triassic collision between the South China and Indochina Blocks, and Middle Triassic intracontinental shearing

    NASA Astrophysics Data System (ADS)

    Faure, Michel; Lin, Wei; Chu, Yang; Lepvrier, Claude

    2016-06-01

    In SE Yunnan, the Ailaoshan Belt has been extensively studied for the ductile shearing coeval with the left-lateral Cenozoic activity of the Red River fault. However, the Late Triassic unconformity of the continental red beds upon metamorphic and ductilely deformed rocks demonstrates that the Ailaoshan Belt was already built up by Early Mesozoic tectonics. From West to East, the belt is subdivided into Western, Central, Eastern Ailaoshan, and Jinping zones. The Western Ailaoshan and Central Ailaoshan zones correspond to a Carboniferous-Permian magmatic arc, and an ophiolitic mélange, respectively. The Eastern Ailaoshan, and the Jinping zones consist of deformed Proterozoic basement and Paleozoic to Early Triassic sedimentary cover series both belonging to the South China Block. This litho-tectonic zonation indicates that the Ailaoshan Belt developed through a SW-directed subduction followed by the collision between Indochina and South China blocks. Crustal thickening triggered per-aluminous magmatism dated at ca 247-240 Ma. Field and microscope-scale top-to-the-NE ductile shearing observed only in the pre-Late Triassic formations, but never in Late Triassic or younger formations, complies with this geodynamic polarity. Furthermore, the late collisional two-mica granitoids and felsic per-aluminous volcanites record a ductile deformation that argues for a continuing crustal shearing deformation after the Early Triassic collision up to the Middle Triassic. Therefore, a two-stage tectonic evolution accounts well for the documented structural and magmatic features. The Triassic architecture of the Ailaoshan Belt, and its geodynamic evolution, correlate well to the South and North with the North Vietnam orogens and the Jinshajiang Belt, respectively.

  14. 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.

  15. Time scales involved in emergent market coherence

    NASA Astrophysics Data System (ADS)

    Kwapień, J.; Drożdż, S.; Speth, J.

    2004-06-01

    In addressing the question of the time scales characteristic for the market formation, we analyze high-frequency tick-by-tick data from the NYSE and from the German market. By using returns on various time scales ranging from seconds or minutes up to 2 days, we compare magnitude of the largest eigenvalue of the correlation matrix for the same set of securities but for different time scales. For various sets of stocks of different capitalization (and the average trading frequency), we observe a significant elevation of the largest eigenvalue with increasing time scale. Our results from the correlation matrix study can be considered as a manifestation of the so-called Epps effect. There is no unique explanation of this effect and it seems that many different factors play a role here. One of such factors is randomness in transaction moments for different stocks. Another interesting conclusion to be drawn from our results is that in the contemporary markets the emergence of significant correlations occurs on time scales much smaller than in the more distant history.

  16. The Laplace transform on time scales revisited

    NASA Astrophysics Data System (ADS)

    Davis, John M.; Gravagne, Ian A.; Jackson, Billy J.; Marks, Robert J., II; Ramos, Alice A.

    2007-08-01

    In this work, we reexamine the time scale Laplace transform as defined by Bohner and Peterson [M. Bohner, A. Peterson, Dynamic Equations on Time Scales: An Introduction with Applications, Birkhauser, Boston, 2001; M. Bohner, A. Peterson, Laplace transform and Z-transform: Unification and extension, Methods Appl. Anal. 9 (1) (2002) 155-162]. In particular, we give conditions on the class of functions which have a transform, develop an inversion formula for the transform, and further, we provide a convolution for the transform. The notion of convolution leads to considering its algebraic structure--in particular the existence of an identity element--motivating the development of the Dirac delta functional on time scales. Applications and examples of these concepts are given.

  17. Global scale precipitation from monthly to centennial scales: empirical space-time scaling analysis, anthropogenic effects

    NASA Astrophysics Data System (ADS)

    de Lima, Isabel; Lovejoy, Shaun

    2016-04-01

    The characterization of precipitation scaling regimes represents a key contribution to the improved understanding of space-time precipitation variability, which is the focus here. We conduct space-time scaling analyses of spectra and Haar fluctuations in precipitation, using three global scale precipitation products (one instrument based, one reanalysis based, one satellite and gauge based), from monthly to centennial scales and planetary down to several hundred kilometers in spatial scale. Results show the presence - similarly to other atmospheric fields - of an intermediate "macroweather" regime between the familiar weather and climate regimes: we characterize systematically the macroweather precipitation temporal and spatial, and joint space-time statistics and variability, and the outer scale limit of temporal scaling. These regimes qualitatively and quantitatively alternate in the way fluctuations vary with scale. In the macroweather regime, the fluctuations diminish with time scale (this is important for seasonal, annual, and decadal forecasts) while anthropogenic effects increase with time scale. Our approach determines the time scale at which the anthropogenic signal can be detected above the natural variability noise: the critical scale is about 20 - 40 yrs (depending on the product, on the spatial scale). This explains for example why studies that use data covering only a few decades do not easily give evidence of anthropogenic changes in precipitation, as a consequence of warming: the period is too short. Overall, while showing that precipitation can be modeled with space-time scaling processes, our results clarify the different precipitation scaling regimes and further allow us to quantify the agreement (and lack of agreement) of the precipitation products as a function of space and time scales. Moreover, this work contributes to clarify a basic problem in hydro-climatology, which is to measure precipitation trends at decadal and longer scales and to

  18. Microbialites and geochemistry of the Early Triassic enigma?

    NASA Astrophysics Data System (ADS)

    Bour, Ivan; Vennin, Emmanuelle; Thomazo, Christophe; Brayard, Arnaud; Olivier, Nicolas; Escarguel, Gilles; Bylund, Kevin G.; Jenks, Jim; Stephen, Daniel A.

    2013-04-01

    The Permian-Triassic mass extinction, 252 Myr ago, is the most devastating global-scale event ever recorded. Ecological and environmental changes during this interval are commonly assumed to be associated with numerous perturbations (i.e. productivity changes, acidification, redox changes, eustatism) that still remain elusive. The present study focus on the relationships between the redox conditions within the water column, the successive sedimentary deposits and marine community turnovers. Our study is based on new Early Triassic sections from the western USA Basin that preserve diversified reefs and bioaccumulations that contain microbialites and various benthic and pelagic organisms (e.g. serpulids, bivalves, ostracods, gastropods, cephalopods). Such a sedimentary prisitine record provides interesting new prospects to decipher the relationships between lithology, microbial structures and the geochemistry of the water column. Three outcrops were studied: the Mineral Mountains, the Confusion Range and the Pahvant Range, that record a general transgressive trend from proximal to distal deposits during the Smithian substage. Continental to open marine conditions are deduced from sedimentological studies and are related to variations of the microbialite meso- and micro-structures over a short time scale. Hydrodynamics and bathymetry are shown to be the major parameters that influence the morphology and distribution of these microbialites. Additionally to the study of the different microbialites structures and associated depositional environments, the chemiotratigraphic record of both carbon isotopes and major elements indicate a complex and a wide range of variations at short time scale. Carbon isotopes vary from -5 to 2 ‰PDB and FeHR/FeT ratio, after iron speciation, indicate a broad range of variation between 0.1 and 1.5. On the one hand, these analyses suggest potential transient oxygen depletion within the water column. On the other hand, fluctuations of these

  19. Analysis of the time scales in time periodic Darcy flows

    NASA Astrophysics Data System (ADS)

    Zhu, T.; Waluga, C.; Wohlmuth, B.; Manhart, M.

    2014-12-01

    We investigate unsteady flow in a porous medium under time - periodic (sinusoidal) pressure gradient. DNS were performed to benchmark the analytical solution of the unsteady Darcy equation with two different expressions of the time scale : one given by a consistent volume averaging of the Navier - Stokes equation [1] with a steady state closure for the flow resistance term, another given by volume averaging of the kinetic energy equation [2] with a closure for the dissipation rate . For small and medium frequencies, the analytical solutions with the time scale obtained by the energy approach compare well with the DNS results in terms of amplitude and phase lag. For large frequencies (f > 100 [Hz]) we observe a slightly smaller damping of the amplitude. This study supports the use of the unsteady form of Darcy's equation with constant coefficients to solve time - periodic Darcy flows at low and medium frequencies. Our DNS simulations, however, indicate that the time scale predicted by the VANS approach together with a steady - state closure for the flow resistance term is too small. The one obtained by the energy approach matches the DNS results well. At large frequencies, the amplitudes deviate slightly from the analytical solution of the unsteady Darcy equation. Note that at those high frequencies, the flow amplitudes remain below 1% of those of steady state flow. This result indicates that unsteady porous media flow can approximately be described by the unsteady Darcy equation with constant coefficients for a large range of frequencies, provided, the proper time scale has been found.

  20. A novel proxy links CAMP volcanism with end-Triassic mass extinction and early Jurassic evolution

    NASA Astrophysics Data System (ADS)

    Ruhl, M.; Bjerrum, C. J.; Frei, R.

    2011-12-01

    Global mass extinction events are marked by a major loss of terrestrial and marine biodiversity and the global collapse of ecosystems during times of extensive volcanic activity and the emplacement of large igneous provinces (LIPs). Large-scale greenhouse gas release, initiated by volcanism, had a profound impact on global geochemical cycles (e.g. initiating strong perturbations in δ13C records). Hence, these events may be regarded as natural deep-time analogues for studying mechanistic feedbacks between rapid and large/scale greenhouse gas emissions, environmental change and biotic crises. Such studies require high resolution stratigraphic correlation between volcanic activity, disruption of global geochemical cycles and biotic crises, which at present is poorly constrained. Here we present a novel proxy that records explosive continental volcanic activity in distant marine shale sediments. The proxy builds on the relative abundance of the trace elements Lu, Hf, Y and Nb (monitored as the (Lu/ Hf)/(Y/ Nb)-ratio). We test the method on a marine sedimentary record comprising Central Atlantic Magmatic Province (CAMP) volcanism and the associated end-Triassic global mass extinction, at ~201.38 Ma. We show that the onset of sharp well-defined peaks in the (Lu/ Hf)/(Y/ Nb)-ratio coincides with the end-Triassic biotic crisis. Subsequent subordinate peaks closely correspond to periods of early Jurassic biotic radiation and evolution. Large-scale volcanic activity therefore not only initiated the end-Triassic mass extinction, it possibly also actively punctuated and regulated the pace of early Jurassic evolution. Further, the proxy also records the timing of Siberian Traps volcanism relative to the end-Permian mass extinction, the largest extinction in Earth's history. Hence, this proxy for the first time allows causality studies between increased volcanic activity, disruption of global geochemical cycles and global biodiversity loss, in unprecedented stratigraphic

  1. Structure of Student Time Management Scale (STMS)

    ERIC Educational Resources Information Center

    Balamurugan, M.

    2013-01-01

    With the aim of constructing a Student Time Management Scale (STMS), the initial version was administered and data were collected from 523 standard eleventh students. (Mean age = 15.64). The data obtained were subjected to Reliability and Factor analysis using PASW Statistical software version 18. From 42 items 14 were dropped, resulting in the…

  2. 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.

  3. Chronology of fluctuating sea levels since the triassic

    SciTech Connect

    Haq, B.U.; Hardenbol, J.; Vail, P.R.

    1987-03-06

    Advances in sequence stratigraphy and the development of depositional models have helped explain the origin of genetically related sedimentary packages during sea level cycles. These concepts have provided the basis for the recognition of sea level events in subsurface data and in outcrops of marine sediments around the world. Knowledge of these events has led to a new generation of Mesozoic and Cenozoic global cycle charts that chronicle the history of sea level fluctuations during the past 250 million years in greater detail than was possible from seismic-stratigraphic data alone. An effort has been made to develop a realistic and accurate time scale and widely applicable chronostratigraphy and to integrate depositional sequences documented in public domain outcrop sections from various basins with this chronostratigraphic framework. A description of this approach and an account of the results, illustrated by sea level cycle charts of the Cenozoic, Cretaceous, Jurassic, and Triassic intervals, are presented.

  4. Chronology of fluctuating sea levels since the triassic.

    PubMed

    Haq, B U; Hardenbol, J; Vail, P R

    1987-03-01

    Advances in sequence stratigraphy and the development of depositional models have helped explain the origin of genetically related sedimentary packages during sea level cycles. These concepts have provided the basis for the recognition of sea level events in subsurface data and in outcrops of marine sediments around the world. Knowledge of these events has led to a new generation of Mesozoic and Cenozoic global cycle charts that chronicle the history of sea level fluctuations during the past 250 million years in greater detail than was possible from seismic-stratigraphic data alone. An effort has been made to develop a realistic and accurate time scale and widely applicable chronostratigraphy and to integrate depositional sequences documented in public domain outcrop sections from various basins with this chronostratigraphic framework. A description of this approach and an account of the results, illustrated by sea level cycle charts of the Cenozoic, Cretaceous, Jurassic, and Triassic intervals, are presented. PMID:17818978

  5. Chronology of Fluctuating Sea Levels since the Triassic

    NASA Astrophysics Data System (ADS)

    Haq, Bilal U.; Hardenbol, Jan; Vail, Peter R.

    1987-03-01

    Advances in sequence stratigraphy and the development of depositional models have helped explain the origin of genetically related sedimentary packages during sea level cycles. These concepts have provided the basis for the recognition of sea level events in subsurface data and in outcrops of marine sediments around the world. Knowledge of these events has led to a new generation of Mesozoic and Cenozoic global cycle charts that chronicle the history of sea level fluctuations during the past 250 million years in greater detail than was possible from seismic-stratigraphic data alone. An effort has been made to develop a realistic and accurate time scale and widely applicable chronostratigraphy and to integrate depositional sequences documented in public domain outcrop sections from various basins with this chronostratigraphic frame-work. A description of this approach and an account of the results, illustrated by sea level cycle charts of the Cenozoic, Cretaceous, Jurassic, and Triassic intervals, are presented.

  6. 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.

  7. Soil Hydrology Across Space And Time Scales

    NASA Astrophysics Data System (ADS)

    Mohanty, B.; Gaur, N.

    2015-12-01

    Soil moisture and hydrologic fluxes at the land surface are critical to climate feedback, hydrology, and biogeochemical cycling. Soil moisture temporal and spatial variability over catchment areas affects surface and subsurface runoff, modulates evaporation and transpiration, determines the extent of groundwater recharge and contaminant transport, and initiates or sustains feedback between the land surface and the atmosphere. At a particular point in time soil moisture content is influenced by: (1) the precipitation history, (2) the texture of the soil, which determines the water-holding capacity, (3) the slope of the land surface, which affects runoff and infiltration, and (4) the vegetation and land cover, which influences evapotranspiration and deep percolation. In other terms the partitioning of soil moisture to recharge to the groundwater, evapotranspiration to the atmosphere, and surface/subsurface runoff to the streams at different spatio-temporal scales and under different hydro-climatic conditions pose one of the greatest challenges to weather and climate prediction, water resources availability, sustainability, quality, and variability in agricultural, range and forested watersheds and hydro-climatic conditions. In this context we hypothesize that: 1) soil moisture variability is dominated by soil properties at the field scale, topographic features at the catchment/watershed scale, and vegetation characteristics and precipitation patterns at the regional scale and beyond; and 2) ensemble hydrologic fluxes (evapotranspiration, infiltration, and shallow ground water recharge) across the vadose zone at the corresponding scale can be effectively represented by one or more soil, topography, vegetation, or climate scale factors. Using ground-based and various active and passive microwave remote sensing measurements during the NASA field campaigns in the past decade we test these hypotheses. Various scaling techniques for soil moisture and soil hydrologic and

  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, Stephen 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. Hemispheric Asymmetries in Substorm Recovery Time Scales

    NASA Technical Reports Server (NTRS)

    Fillingim, M. O.; Chua, D H.; Germany, G. A.; Spann, James F.

    2009-01-01

    Previous statistical observations have shown that the recovery time scales of substorms occurring in the winter and near equinox (when the nighttime auroral zone was in darkness) are roughly twice as long as the recovery time scales for substorms occurring in the summer (when the nighttime auroral region was sunlit). This suggests that auroral substorms in the northern and southern hemispheres develop asymmetrically during solstice conditions with substorms lasting longer in the winter (dark) hemisphere than in the summer (sunlit) hemisphere. Additionally, this implies that more energy is deposited by electron precipitation in the winter hemisphere than in the summer one during substorms. This result, coupled with previous observations that have shown that auroral activity is more common when the ionosphere is in darkness and is suppressed when the ionosphere is in daylight, strongly suggests that the ionospheric conductivity plays an important role governing how magnetospheric energy is transferred to the ionosphere during substorms. Therefore, the ionosphere itself may dictate how much energy it will accept from the magnetosphere during substorms rather than this being an externally imposed quantity. Here, we extend our earlier work by statistically analyzing the recovery time scales for a large number of substorms observed in the conjugate hemispheres simultaneously by two orbiting global auroral imagers: Polar UVI and IMAGE FUV. Our current results are consistent with previous observations. The recovery time scales are observed to be longer in the winter (dark) hemisphere while the auroral activity has a shorter duration in the summer (sunlit) hemisphere. This leads to an asymmetric energy input from the magnetosphere to the ionosphere with more energy being deposited in the winter hemisphere than in the summer hemisphere.

  10. Liquidity crises on different time scales

    NASA Astrophysics Data System (ADS)

    Corradi, Francesco; Zaccaria, Andrea; Pietronero, Luciano

    2015-12-01

    We present an empirical analysis of the microstructure of financial markets and, in particular, of the static and dynamic properties of liquidity. We find that on relatively large time scales (15 min) large price fluctuations are connected to the failure of the subtle mechanism of compensation between the flows of market and limit orders: in other words, the missed revelation of the latent order book breaks the dynamical equilibrium between the flows, triggering the large price jumps. On smaller time scales (30 s), instead, the static depletion of the limit order book is an indicator of an intrinsic fragility of the system, which is related to a strongly nonlinear enhancement of the response. In order to quantify this phenomenon we introduce a measure of the liquidity imbalance present in the book and we show that it is correlated to both the sign and the magnitude of the next price movement. These findings provide a quantitative definition of the effective liquidity, which proves to be strongly dependent on the considered time scales.

  11. Multidimensional scaling of musical time estimations.

    PubMed

    Cocenas-Silva, Raquel; Bueno, José Lino Oliveira; Molin, Paul; Bigand, Emmanuel

    2011-06-01

    The aim of this study was to identify the psycho-musical factors that govern time evaluation in Western music from baroque, classic, romantic, and modern repertoires. The excerpts were previously found to represent variability in musical properties and to induce four main categories of emotions. 48 participants (musicians and nonmusicians) freely listened to 16 musical excerpts (lasting 20 sec. each) and grouped those that seemed to have the same duration. Then, participants associated each group of excerpts to one of a set of sine wave tones varying in duration from 16 to 24 sec. Multidimensional scaling analysis generated a two-dimensional solution for these time judgments. Musical excerpts with high arousal produced an overestimation of time, and affective valence had little influence on time perception. The duration was also overestimated when tempo and loudness were higher, and to a lesser extent, timbre density. In contrast, musical tension had little influence. PMID:21853763

  12. The Middle Triassic magnetostratigraphy from the Peri-Tethys basin in Poland

    NASA Astrophysics Data System (ADS)

    Nawrocki, Jerzy; Szulc, Joachim

    2000-10-01

    The paper presents the first complete magnetic polarity scale obtained for the Middle Triassic of the northern Peri-Tethys area. The Roetian and Muschelkalk deposits of southern Poland (Upper Silesia, the Holy Cross Mountains) were studied paleomagnetically. The obtained paleopole 'A' (52°N, 143°E) fits well to the Middle Triassic (ca. 240 Ma) segment of the Stable European APWP. A set of various quality characteristic directions isolated in 106 samples was used for construction of the composite polarity scale. This Peritethyan scale has been tied with conodont zonation and referred to the scale erected earlier in the Tethyan realm. Comparison of both scales indicates that the whole Roetian succession in the southern Polish basin should be correlated with the latest Olenekian. The normal marine sedimentation ceased in the Polish basin as early as in the late Fassanian time. The obtained magnetostratigraphic scale combined with the sequence stratigraphic framework enables a reliable chronological correlation of the late Olenekian-Ladinian succession over the entire Peri-Tethys Basin.

  13. Cell water dynamics on multiple time scales

    PubMed Central

    Persson, Erik; Halle, Bertil

    2008-01-01

    Water–biomolecule interactions have been extensively studied in dilute solutions, crystals, and rehydrated powders, but none of these model systems may capture the behavior of water in the highly organized intracellular milieu. Because of the experimental difficulty of selectively probing the structure and dynamics of water in intact cells, radically different views about the properties of cell water have proliferated. To resolve this long-standing controversy, we have measured the 2H spin relaxation rate in living bacteria cultured in D2O. The relaxation data, acquired in a wide magnetic field range (0.2 mT–12 T) and analyzed in a model-independent way, reveal water dynamics on a wide range of time scales. Contradicting the view that a substantial fraction of cell water is strongly perturbed, we find that ≈85% of cell water in Escherichia coli and in the extreme halophile Haloarcula marismortui has bulk-like dynamics. The remaining ≈15% of cell water interacts directly with biomolecular surfaces and is motionally retarded by a factor 15 ± 3 on average, corresponding to a rotational correlation time of 27 ps. This dynamic perturbation is three times larger than for small monomeric proteins in solution, a difference we attribute to secluded surface hydration sites in supramolecular assemblies. The relaxation data also show that a small fraction (≈0.1%) of cell water exchanges from buried hydration sites on the microsecond time scale, consistent with the current understanding of protein hydration in solutions and crystals. PMID:18436650

  14. A perspective on time: Loss frequencies, time scales, and lifetimes

    NASA Astrophysics Data System (ADS)

    Prather, Michael; Holmes, Christopher

    2013-04-01

    The need to describe the Earth system and its components with a quantity that has units of time is ubiquitous since the 1970s work of Bolin, Rodhe and Junge. These quantities are often used as metrics of the system to describe the duration or cumulative impact of an action, such as in global-warming and ozone-depletion potentials, as in the SPARC lifetime re-assessment. The quantity designated "lifetime" is often calculated inconsistently and/or misused when applied to the subsequent evaluations of impacts. A careful set of definitions and derivations is needed to ensure that we are reporting, publishing, and comparing the same quantities. There are many different ways to derive metrics of time, and they describe different properties of the system. Here we carefully define several of those metrics - denoted here as loss frequency, time scale, and lifetime - and demonstrate which properties of the system they describe. Three generalizable examples demonstrate (i) how the non-linear chemistry of tropospheric ozone makes simple approaches for tracking pollution in error; (ii) why the lifetime of a gas depends on the history of emissions, and (iii) when multiple reservoirs generate time scales quite separate from the traditionally defined lifetime. Proper use of the many "time" parameters in a system, however, gives a very powerful understanding of the response to anthropogenic perturbations.

  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. Deciphering Time Scale Hierarchy in Reaction Networks.

    PubMed

    Nagahata, Yutaka; Maeda, Satoshi; Teramoto, Hiroshi; Horiyama, Takashi; Taketsugu, Tetsuya; Komatsuzaki, Tamiki

    2016-03-01

    Markovian dynamics on complex reaction networks are one of the most intriguing subjects in a wide range of research fields including chemical reactions, biological physics, and ecology. To represent the global kinetics from one node (corresponding to a basin on an energy landscape) to another requires information on multiple pathways that directly or indirectly connect these two nodes through the entire network. In this paper we present a scheme to extract a hierarchical set of global transition states (TSs) over a discrete-time Markov chain derived from first-order rate equations. The TSs can naturally take into account the multiple pathways connecting any pair of nodes. We also propose a new type of disconnectivity graph (DG) to capture the hierarchical organization of different time scales of reactions that can capture changes in the network due to changes in the time scale of observation. The crux is the introduction of the minimum conductance cut (MCC) in graph clustering, corresponding to the dividing surface across the network having the "smallest" transition probability between two disjoint subnetworks (superbasins on the energy landscape) in the network. We present a new combinatorial search algorithm for finding this MCC. We apply our method to a reaction network of Claisen rearrangement of allyl vinyl ether that consists of 23 nodes and 66 links (saddles on the energy landscape) connecting them. We compare the kinetic properties of our DG to those of the transition matrix of the rate equations and show that our graph can properly reveal the hierarchical organization of time scales in a network. PMID:26641663

  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. 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.

  19. Filling the Triassic Geochronologic Gap: A Continuous Cored Record of Continental Environmental Change in Western North America

    NASA Astrophysics Data System (ADS)

    Olsen, P. E.; Kent, D. V.; Geissman, J. W.; Mundil, R.; Gehrels, G. E.; Irmis, R. B.; Whiteside, J. H.; Schaller, M. F.

    2013-12-01

    The Triassic Period (252.2-201.6 Ma) is bracketed by two mass extinctions, witnessed the evolution of the major groups of modern tetrapods, saw giant bolide impacts, and was typified by generally high atmospheric CO2 and a lack of ice at the poles. Testing hypotheses relevant to these major features of the Triassic, as well as problems related to the Earth system in general, requires temporally well-defined records of environmental and biotic change, especially in terrestrial environments, which until recently were lacking. The NSF and ICDP funded ~500 m long core at Petrified Forest National Park, scheduled to be drilled in Fall, 2013, is part of an interdisciplinary, multi-institutional, Colorado Plateau Coring Project, and is a major step towards providing a network of such records. The core will recover virtually the entire pre-Owl-Rock-Member Late Triassic age Chinle and underlying Early-Middle Triassic age Moenkopi formations. A core is required despite excellent outcrop and a long and distinguished history of study because of ambiguities in local correlation, a lack of constraints on the temporal duration and resolution of biotic events, and an inability to make clear global correlations. Specifically, by integrating a densely sampled paleomagnetic record with high-resolution radioisotopic ages in unquestioned superposition, the new core will allow us to test at least five sets of hypotheses: (1) were marine and continental biotic turnover events in the Late Triassic coupled? (2) was there high faunal provinciality during the existence of the supercontinent of Pangea?; (3) is the time scale of the Newark basin astronomically calibrated GPTS for the Triassic accurate, particularly for the Norian age part that is relevant for mapping the chaotic evolution of the Solar System, as well as global correlations?; (4) is the supposed Carnian-Norian boundary in the Chinle actually a late middle Norian extinction coinciding with the 215.5 Ma Manicouagan impact?; (5

  20. Time sequence and time scale of intermediate mass fragment emission

    SciTech Connect

    De Filippo, E.; Pagano, A.; Cardella, G.; Lanzano, G.; Papa, M.; Pirrone, S.; Politi, G.; Wilczynski, J.

    2005-04-01

    Semiperipheral collisions in the {sup 124}Sn+{sup 64}Ni reaction at 35 MeV/nucleon were studied using the forward part of the Charged Heavy Ion Mass and Energy Resolving Array. Nearly completely determined ternary events involving projectilelike fragments (PLF), targetlike fragments (TLF), and intermediate mass fragments (IMF) were selected. A new method of studying the reaction mechanism, focusing on the analysis of the correlations between relative velocities in the IMF+PLF and IMF+TLF subsystems, is proposed. The relative velocity correlations provide information on the time sequence and time scale of the neck fragmentation processes leading to production of IMFs. It is shown that the majority of light IMFs are produced within 40-80 fm/c after the system starts to reseparate. Heavy IMFs are formed at times of about 120 fm/c or later and can be viewed as resulting from two-step (sequential) neck rupture processes.

  1. Assessing the record and causes of Late Triassic extinctions

    USGS Publications Warehouse

    Tanner, L.H.; Lucas, S.G.; Chapman, M.G.

    2004-01-01

    Accelerated biotic turnover during the Late Triassic has led to the perception of an end-Triassic mass extinction event, now regarded as one of the "big five" extinctions. Close examination of the fossil record reveals that many groups thought to be affected severely by this event, such as ammonoids, bivalves and conodonts, instead were in decline throughout the Late Triassic, and that other groups were relatively unaffected or subject to only regional effects. Explanations for the biotic turnover have included both gradualistic and catastrophic mechanisms. Regression during the Rhaetian, with consequent habitat loss, is compatible with the disappearance of some marine faunal groups, but may be regional, not global in scale, and cannot explain apparent synchronous decline in the terrestrial realm. Gradual, widespread aridification of the Pangaean supercontinent could explain a decline in terrestrial diversity during the Late Triassic. Although evidence for an impact precisely at the boundary is lacking, the presence of impact structures with Late Triassic ages suggests the possibility of bolide impact-induced environmental degradation prior to the end-Triassic. Widespread eruptions of flood basalts of the Central Atlantic Magmatic Province (CAMP) were synchronous with or slightly postdate the system boundary; emissions of CO2 and SO2 during these eruptions were substantial, but the contradictory evidence for the environmental effects of outgassing of these lavas remains to be resolved. A substantial excursion in the marine carbon-isotope record of both carbonate and organic matter suggests a significant disturbance of the global carbon cycle at the system boundary. Release of methane hydrates from seafloor sediments is a possible cause for this isotope excursion, although the triggering mechanism and climatic effects of such a release remain uncertain. ?? 2003 Elsevier B.V. All rights reserved.

  2. Parametric instabilities in picosecond time scales

    SciTech Connect

    Baldis, H.A.; Rozmus, W.; Labaune, C.; Mounaix, Ph.; Pesme, D.; Baton, S.; Tikhonchuk, V.T.

    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.

  3. 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.

  4. 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

  5. The end-triassic mass extinction event

    NASA Technical Reports Server (NTRS)

    Hallam, A.

    1988-01-01

    The end-Triassic is the least studied of the five major episodes of mass extinction recognized in the Phanerozoic, and the Triassic-Jurassic boundary is not precisely defined in most parts of the world, with a paucity of good marine sections and an insufficiency of biostratigraphically valuable fossils. Despite these limitations it is clear that there was a significant episode of mass extinction, affecting many groups, in the Late Norian and the existing facts are consistent with it having taken place at the very end of the period. The best record globally comes from marine strata. There was an almost complete turnover of ammonites across the T-J boundary, with perhaps no more than one genus surviving. About half the bivalve genera and most of the species went extinct, as did many archaeogastropods. Many Paleozoic-dominant brachiopods also disappeared, as did the last of the conodonts. There was a major collapse and disappearance of the Alpine calcareous sponge. Among terrestrial biota, a significant extinction event involving tetrapods was recognized. With regard to possible environmental events that may be postulated to account for the extinctions, there is no evidence of any significant global change of climate at this time. The existence of the large Manicouagan crater in Quebec, dated as about late or end-Triassic, has led to the suggestion that an impact event might be implicated, but so far despite intensive search no unequivocal iridium anomaly or shocked quartz was discovered. On the other hand there is strong evidence for significant marine regression in many parts of the world. It is proposed therefore that the likeliest cause of the marine extinctions is severe reduction in habitat area caused either by regression of epicontinental seas, subsequent widespread anoxia during the succeeding transgression, or a combination of the two.

  6. New carbon-isotope evidence from the Polish Basin for a major carbon-cycle perturbation at the Triassic-Jurassic Boundary

    NASA Astrophysics Data System (ADS)

    Pointer, Robyn; Hesselbo, Stephen; Littler, Kate; Pieńkowski, Grzegorz; Hodbod, Marta

    2016-04-01

    Carbon-isotope analysis of fossil plant material from a Polish core provides new evidence of a perturbation to the atmospheric carbon-cycle at the Triassic-Jurassic boundary (~201 Ma). The Triassic-Jurassic boundary was a time of extreme climate change which also coincided with the end-Triassic mass extinction. The new data will allow us to identify climatic changes in the Polish Basin across the Triassic-Jurassic boundary and evaluate these changes on a broader scale by comparison to data from other sites located around the world. The Niekłan borehole core, located in the southern Polish Basin, provides a ~200 metre-long terrestrial record spanning the Rhaetian and Hettangian, including the Triassic-Jurassic boundary (~208-199 Ma). The Niekłan core consists of interbedded fluvial and lacustrine sediments containing preserved plant material and thus provides an excellent opportunity to study both terrestrial palaeoenvironmental changes in the Polish Basin and perturbations in the carbon-cycle more broadly. Carbon-isotope analysis of macrofossil plant material and microscopic woody phytoclasts from the Niekłan core reveals a negative carbon-isotope excursion (CIE) of ~-3‰ at the end of the Rhaetian, before a gradual return to more positive values thereafter. The negative CIE suggests an injection of isotopically-light carbon into the atmosphere occurred just before the Triassic-Jurassic boundary. Likely sources of this carbon include volcanogenic gases, methane released from gas hydrates, or a combination of the two. The negative CIE seen in plant material at Niekłan is also recorded in a variety of geological materials from contemporaneous sites world-wide. These time-equivalent, but geographically separated, records indicate that the negative CIE recorded in the Niekłan plant material is the result of a regional or global carbon-cycle perturbation and is not merely a local signal. Future work will focus on using a range of palaeoenvironmental proxies in

  7. 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

  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

  9. Time Horizon and Social Scale in Communication

    NASA Astrophysics Data System (ADS)

    Krantz, D. H.

    2010-12-01

    In 2009 our center (CRED) published a first version of The Psychology of Climate Change Communication. In it, we attempted to summarize facts and concepts from psychological research that could help guide communication. While this work focused on climate change, most of the ideas are at least partly applicable for communication about a variety of natural hazards. Of the many examples in this guide, I mention three. Single-action bias is the human tendency to stop considering further actions that might be needed to deal with a given hazard, once a single action has been taken. Another example is the importance of group affiliation in motivating voluntary contributions to joint action. A third concerns the finding that group participation enhances understanding of probabilistic concepts and promotes action in the face of uncertainty. One current research direction, which goes beyond those included in the above publication, focuses on how time horizons arise in the thinking of individuals and groups, and how these time horizons might influence hazard preparedness. On the one hand, individuals sometimes appear impatient, organizations look for immediate results, and officials fail to look beyond the next election cycle. Yet under some laboratory conditions and in some subcultures, a longer time horizon is adopted. We are interested in how time horizon is influenced by group identity and by the very architecture of planning and decision making. Institutional changes, involving long-term contractual relationships among communities, developers, insurers, and governments, could greatly increase resilience in the face of natural hazards. Communication about hazards, in the context of such long-term contractual relationships might look very different from communication that is first initiated by immediate threat. Another new direction concerns the social scale of institutions and of communication about hazards. Traditionally, insurance contracts share risk among a large

  10. Triassic deposits of the Chukotka Arctic continental margin (sedimentary implications and detrital zircon data)

    NASA Astrophysics Data System (ADS)

    Tuchkova, Marianna; Sokolov, Sergey; Verzhbitsky, Vladimir

    2013-04-01

    Triassic clastic deposits of Chukotka are represented by rhythmic intercalation of sandstones, siltstones and mudstones. During the Triassic, sedimentation was represented by continental slope progradation. Detrital zircons from Triassic sedimentary rocks were collected for constrain its paleogeographic links to source terranes. Zircons populations from three Chukotka's samples are very similar, and youngest zircon ages show peaks at 236-255 Ma (Miller et al., 2006). Lower Triassic sandstones from the Chaun subterrane do not contain the young population 235-265 Ma that is characteristic of the Upper Triassic rocks from the Anyui subterrane and Wrangel Island. The young zircon population is missing also from the coeval Sadlerochit Group (Alaska) and Blind Fiord Formation of the Sverdrup basin (Miller et al., 2006; Omma et al., 2011). Our data of Triassic sandstones of Wrangel island demonstrate detrital zircons ages dominated by Middle Triassic (227-245 Ma), Carboniferous (309-332 Ma) and Paleoproterozoic (1808-2500 Ma) ages. The new data on Chukotka show that populations of detrital zircons from Chukotka, the Sverdrup basin, and Alaska, the Sadlerochit Mountains included, demonstrate greater similarity than it was previously thought. Consequently, it may be assumed that they originate from a single source situated in the north. The data on zircon age of gabbro-dolerite magmatism in eastern Chukotka (252 Ma. Ledneva et al., 2011) and K-Ar ages obtained for sills and small intrusive bodies (Geodynamics…, 2006) in Lower Triassic deposits allow the local provenance. The presence of products of synchronous magmatism and shallow-water facies in the Lower Triassic sequences confirm this assumption. At the same time, coeval zircons appear only in the Upper Triassic strata. It is conceivable that the young zircon population originates from intrusive, not volcanic rocks, which were subjected to erosion only in the Late Triassic. In our opinion, the assumption of the local

  11. Times Scales in Dense Granular Material

    NASA Astrophysics Data System (ADS)

    Zhang, Duan

    2005-07-01

    Forces in dense granular material are transmitted through particle contacts. The evolution of the contact stress is directly related to dynamical interaction forces between particles. Since particle contacts in a dense granular material are random, a statistical method is employed to describe and model their motions. It is found that the time scales of particle contacts determinate stress relaxation and the fluid- like or solid-like behavior of the material. Numerical simulations are performed to calculate statistical properties of particle interactions. Using results from the numerical simulations we examine the relationship between the averaged local deformation field and the macroscopic deformation field. We also examine the relationship between the averaged local interaction force and the averaged stress field in the material. Validities of the Voigt and the Reuss assumptions are examined; and extensions to these assumptions are studied. Numerical simulations show that tangential frictions between particles significantly increase the contact stress, while the direct contribution of the tangential force to the stress is small. This puzzling observation can be explained by dependency of the relaxation time on the tangential friction.

  12. Time Scales, Bedforms and Bedload Transport

    NASA Astrophysics Data System (ADS)

    Dhont, B.

    2015-12-01

    Bedload transport rates in mountain streams may exhibit wide fluctuations even under constant flow conditions. A better understanding of bedload pulses is key to predict natural hazards induced by torrential activity and sediment issues in mountainous areas. Several processes such as bedforms migration, grain sorting and random particles' trajectories are evoked as the driving agents of pulse formation and development. Quantifying the effects of these processes is a difficult task. This work aims to investigate the interactions between bedload transport and bedform dynamics in steep gravel-bed rivers. Experiments are carried out in a 17-m long 60-cm wide flume inclined at an angle of 2.7%. The bed is initially flat and made of homogenous natural gravel with a mean diameter of 6 mm. We imposed 200 identical hydrographs (of 1 hr duration) at the flume inlet (the bed surface was not flattened out during these cycling floods). The input hydrograph and the input sediment discharge are nearly triangular. Bed topography is measured after each flood using ultrasound sensors while the bedload transport rate is steadily monitored at the outlet using accelerometers (accelerometers fixed on metallic plates record the impacts of the grains flowing out of the flume). For the sake of comparison, a similar experiment consisting of 19 floods of 10 hours is carried out under constant supply conditions. We show that accelerometers are a cost effective technique to obtain high-frequency bedload discharge data. Spectral analysis of the bedload timeseries is used to highlight the different time scales corresponding to different bedload transport processes. We show that long timeseries are necessary to capture the different processes that drive bedload transport, including the resilience time after a perturbation of the bed. The alternate bars that develop and migrate along the flume are found to significantly influence bedload transport rate fluctuations.

  13. An optimal modification of a Kalman filter for time scales

    NASA Technical Reports Server (NTRS)

    Greenhall, C. A.

    2003-01-01

    The Kalman filter in question, which was implemented in the time scale algorithm TA(NIST), produces time scales with poor short-term stability. A simple modification of the error covariance matrix allows the filter to produce time scales with good stability at all averaging times, as verified by simulations of clock ensembles.

  14. 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.

  15. 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

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

    SciTech Connect

    Schubert, J.K.; Bottjer, D.J. )

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

    The transition from the Triassic to Jurassic Period, initiating the 'Age of the dinosaurs', approximately 200 Ma, 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 a causal relationship is still debated. The Triassic-Jurassic (T-J) boundary is recently proposed in the marine record at the first occurrence datum of Jurassic ammonites, post-dating the extinction interval that concurs with two distinct perturbations in the carbon isotope record. The continental record shows a major palynological turnover together with a prominent change in tetrapod taxa, but a direct link to the marine events is still equivocal. Here we develop an accurate chronostratigraphic framework for the T-J boundary interval and establish detailed trans-Atlantic and marine-continental correlations by integrating astrochronology, paleomagnetism, basalt geochemistry and geobiology. We show that the oldest CAMP basalts are diachronous by 20 kyr across the Atlantic Ocean, and that these two volcanic pulses coincide with the end-Triassic extinction interval in the marine realm. Our results support the hypotheses of Phanerozoic mass extinctions resulting from emplacement of Large Igneous Provinces (LIPs) and provide crucial time constraints for numerical modelling of Triassic-Jurassic climate change and global carbon-cycle perturbations.

  18. Time scales in Galveston Bay: An unsteady estuary

    NASA Astrophysics Data System (ADS)

    Rayson, Matthew D.; Gross, Edward S.; Hetland, Robert D.; Fringer, Oliver B.

    2016-04-01

    Estuarine time scales including the turnover, particle e-folding time, the age (calculated with a passive tracer), and residence time (calculated with Lagrangian particles) were computed using a three-dimensional hydrodynamic model of Galveston Bay, a low-flow, partially stratified estuary. Time scales were computed during a time period when river flow varied by several orders of magnitude and all time scales therefore exhibited significant temporal variability because of the unsteadiness of the system. The spatial distributions of age and residence time were qualitatively similar and increased from 15 days in a shipping channel to >45 days in the upper estuary. Volume-averaged age and residence time decreased during high-flow conditions. Bulk time scales, including the freshwater and salinity turnover times, were far more variable due to the changing river discharge and salt flux through the estuary mouth. A criterion for calculating a suitable averaging time is discussed to satisfy a steady state assumption and to estimate a more representative bulk time scale. When scaled with a freshwater advective time, all time scales were approximately equal to the advective time scale during high-flow conditions and many times higher during low-flow conditions. The mean age, Lagrangian residence, and flushing times exhibited a relationship that was weakly dependent on the freshwater advective time scale demonstrating predictability even in an unsteady, realistic estuary.

  19. A Quaternary Geomagnetic Instability Time Scale

    NASA Astrophysics Data System (ADS)

    Singer, B. S.

    2013-12-01

    Reversals and excursions of Earth's geomagnetic field create marker horizons that are readily detected in sedimentary and volcanic rocks worldwide. An accurate and precise chronology of these geomagnetic field instabilities is fundamental to understanding several aspects of Quaternary climate, dynamo processes, and surface processes. For example, stratigraphic correlation between marine sediment and polar ice records of climate change across the cryospheres benefits from a highly resolved record of reversals and excursions. The temporal patterns of dynamo behavior may reflect physical interactions between the molten outer core and the solid inner core or lowermost mantle. These interactions may control reversal frequency and shape the weak magnetic fields that arise during successive dynamo instabilities. Moreover, weakening of the axial dipole during reversals and excursions enhances the production of cosmogenic isotopes that are used in sediment and ice core stratigraphy and surface exposure dating. The Geomagnetic Instability Time Scale (GITS) is based on the direct dating of transitional polarity states recorded by lava flows using the 40Ar/39Ar method, in parallel with astrochronologic age models of marine sediments in which O isotope and magnetic records have been obtained. A review of data from Quaternary lava flows and sediments yields a GITS comprising 10 polarity reversals and 27 excursions during the past 2.6 million years. Nine of the ten reversals bounding chrons and subchrons are associated with 40Ar/39Ar ages of transitionally-magnetized lava flows. The tenth, the Guass-Matuyama chron boundary, is tightly bracketed by 40Ar/39Ar dated ash deposits. Of the 27 well-documented excursions, 14 occurred during the Matuyama chron and 13 during the Brunhes chron; 19 have been dated directly using the 40Ar/39Ar method on transitionally-magnetized volcanic rocks and form the backbone of the GITS. Excursions are clearly not the rare phenomena once thought

  20. Ecosystem remodelling among vertebrates at the Permian-Triassic boundary in Russia.

    PubMed

    Benton, M J; Tverdokhlebov, V P; Surkov, M V

    2004-11-01

    The mass extinction at the Permian-Triassic boundary, 251 million years (Myr) ago, is accepted as the most profound loss of life on record. Global data compilations indicate a loss of 50% of families or more, both in the sea and on land, and these figures scale to a loss of 80-96% of species, based on rarefaction analyses. This level of loss is confirmed by local and regional-scale studies of marine sections, but the terrestrial record has been harder to analyse in such close detail. Here we document the nature of the event in Russia in a comprehensive survey of 675 specimens of amphibians and reptiles from 289 localities spanning 13 successive geological time zones in the South Urals basin. These changes in diversity and turnover cannot be explained simply by sampling effects. There was a profound loss of genera and families, and simplification of ecosystems, with the loss of small fish-eaters and insect-eaters, medium and large herbivores and large carnivores. Faunal dynamics also changed, from high rates of turnover through the Late Permian period to greater stability at low diversity through the Early Triassic period. Even after 15 Myr of ecosystem rebuilding, some guilds were apparently still absent-small fish-eaters, small insect-eaters, large herbivores and top carnivores. PMID:15525988

  1. On time scales and time synchronization using LORAN-C as a time reference signal

    NASA Technical Reports Server (NTRS)

    Chi, A. R.

    1974-01-01

    The long term performance of the eight LORAN-C chains is presented in terms of the Coordinated Universal Time (UTC) of the U.S. Naval Observatory (USNO); and the use of the LORAN-C navigation system for maintaining the user's clock to a UTC scale is described. The atomic time scale and the UTC of several national laboratories and observatories relative to the international atomic time are reported. Typical performance of several NASA tracking station clocks, relative to the USNO master clock, is also presented.

  2. 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…

  3. Astronomical tuning of the end-Permian extinction and the Early Triassic Epoch of South China and Germany

    NASA Astrophysics Data System (ADS)

    Li, Mingsong; Ogg, James; Zhang, Yang; Huang, Chunju; Hinnov, Linda; Chen, Zhong-Qiang; Zou, Zhuoyan

    2016-05-01

    The timing of the end-Permian mass extinction and subsequent prolonged recovery during the Early Triassic Epoch can be established from astronomically controlled climate cycles recorded in continuous marine sedimentary sections. Astronomical-cycle tuning of spectral gamma-ray logs from biostratigraphically-constrained cyclic stratigraphy through marine sections at Meishan, Chaohu, Daxiakou and Guandao in South China yields an integrated time scale for the Early Triassic, which is consistent with scaling of magnetostratigraphy from climatic cycles in continental deposits of the Germanic Basin. The main marine mass extinction interval at Meishan is constrained to less than 40% of a 100-kyr (kilo-year) cycle (i.e., <40 kyr) and the sharp negative excursion in δ13C is estimated to have lasted <6 kyr. The sharp positive shift in δ13C from - 2 ‰ to 4‰ across the Smithian-Spathian boundary at Chaohu was completed in 50 kyr. The earliest marine reptiles in the Mesozoic at Chaohu that are considered to represent a significant recovery of marine ecosystems did not appear until 4.7 myr (million years) after the end-Permian extinction. The durations of the Griesbachian, Dienerian, Smithian and Spathian substages, including the uncertainty in placement of widely used conodont biostratigraphic datums for their boundaries, are 1.4 ± 0.1, 0.6 ± 0.1, 1.7 ± 0.1 and 1.4 ± 0.1 myr, implying a total span for the Early Triassic of 5.1 ± 0.1 myr. Therefore, relative to an assigned 251.902 ± 0.024 Ma for the Permian-Triassic boundary from the Meishan GSSP, the ages for these substage boundaries are 250.5 ± 0.1 Ma for base Dienerian, 249.9 ± 0.1 Ma for base Smithian (base of Olenekian stage), 248.2 ± 0.1 Ma for base Spathian, and 246.8 ± 0.1 Ma for the base of the Anisian Stage. This astronomical-calibrated timescale provides rates for the recurrent carbon isotope excursions and for trends in sedimentation accumulation through the Early Triassic of studied sections in South

  4. A Major Unconformity Between Permian and Triassic Strata at Cape Kekurnoi, Alaska Peninsula: Old and New Observations on Stratigraphy and Hydrocarbon Potential

    USGS Publications Warehouse

    Blodgett, Robert B.; Sralla, Bryan

    2008-01-01

    A major angular unconformity separates carbonates and shales of the Upper Triassic Kamishak Formation from an underlying unnamed sequence of Permian agglomerate, volcaniclastic rocks (sandstone), and limestone near Puale Bay on the Alaska Peninsula. For the first time, we photographically document the angular unconformity in outcrop, as clearly exposed in a seacliff ~1.3 mi (2.1 km) west of Cape Kekurnoi in the Karluk C?4 and C?5 1:63,360-scale quadrangles. This unconformity is also documented by examination of core chips, ditch cuttings, and (or) open-hole electrical logs in two deep oil-and-gas-exploration wells (Humble Oil & Refining Co.?s Bear Creek No. 1 and Standard Oil Co. of California?s Grammer No. 1) drilled along the Alaska Peninsula southwest of Puale Bay. A third well (Richfield Oil Corp.?s Wide Bay Unit No. 1), south of and structurally on trend with the other two wells, probed deeply into the Paleozoic basement, but Triassic strata are absent, owing to either a major unconformity or a large fault. Here we briefly review current and newly acquired data on Permian and Triassic rocks of the Puale Bay-Becharof Lake-Wide Bay area on the basis of an examination of surface and subsurface materials. The resulting reinterpretation of the Permian and Triassic stratigraphy has important economic ramifications for oil and gas exploration on the Alaska Peninsula and in the Cook Inlet basin. We also present a history of petroleum exploration targeting Upper Triassic reservoirs in the region.

  5. Detecting separate time scales in genetic expression data

    PubMed Central

    2010-01-01

    Background Biological processes occur on a vast range of time scales, and many of them occur concurrently. As a result, system-wide measurements of gene expression have the potential to capture many of these processes simultaneously. The challenge however, is to separate these processes and time scales in the data. In many cases the number of processes and their time scales is unknown. This issue is particularly relevant to developmental biologists, who are interested in processes such as growth, segmentation and differentiation, which can all take place simultaneously, but on different time scales. Results We introduce a flexible and statistically rigorous method for detecting different time scales in time-series gene expression data, by identifying expression patterns that are temporally shifted between replicate datasets. We apply our approach to a Saccharomyces cerevisiae cell-cycle dataset and an Arabidopsis thaliana root developmental dataset. In both datasets our method successfully detects processes operating on several different time scales. Furthermore we show that many of these time scales can be associated with particular biological functions. Conclusions The spatiotemporal modules identified by our method suggest the presence of multiple biological processes, acting at distinct time scales in both the Arabidopsis root and yeast. Using similar large-scale expression datasets, the identification of biological processes acting at multiple time scales in many organisms is now possible. PMID:20565716

  6. The terminal Permian in European Russia: Vyaznikovian Horizon, Nedubrovo Member, and Permian-Triassic boundary

    NASA Astrophysics Data System (ADS)

    Lozovsky, V. R.; Balabanov, Yu. P.; Karasev, E. V.; Novikov, I. V.; Ponomarenko, A. G.; Yaroshenko, O. P.

    2016-07-01

    The comprehensive analysis of the data obtained on terrestrial vertebrata, ostracods, entomologic fauna, megaflora, and microflora in deposits of the Vyaznikovian Horizon and Nedubrovo Member, as well as the paleomagnetic data measured in enclosing rocks, confirms heterogeneity of these deposits. Accordingly, it is necessary to distinguish these two stratons in the terminal Permian of the East European Platform. The combined sequence of Triassic-Permian boundary deposits in the Moscow Syneclise, which is considered to be the most complete sequence in the East European Platform, is as follows (from bottom upward): Vyatkian deposits; Vyaznikovian Horizon, including Sokovka and Zhukovo members; Nedubrovo Member (Upper Permian); Astashikha and Ryabi members of the Vokhmian Horizon (Lower Triassic). None of the sequences of Permian-Triassic boundary deposits known in the area of study characterizes this sequence in full volume. In the north, the Triassic deposits are underlain by the Nedubrovo Member; in the south (the Klyazma River basin), the sections are underlain by the Vyaznikovian Horizon. The Permian-Triassic boundary adopted in the General Stratigraphic Scale of Russia for continental deposits of the East European platform (the lower boundary of the Astashikha Member) is more ancient than the one adopted in the International Stratigraphic Chart. The same geological situation is observed in the German Basin and other localities where Triassic continental deposits are developed. The ways of solving this problem are discussed in this article.

  7. Deep-sea record of impact apparently unrelated to mass extinction in the Late Triassic

    PubMed Central

    Onoue, Tetsuji; Sato, Honami; Nakamura, Tomoki; Noguchi, Takaaki; Hidaka, Yoshihiro; Shirai, Naoki; Ebihara, Mitsuru; Osawa, Takahito; Hatsukawa, Yuichi; Toh, Yosuke; Koizumi, Mitsuo; Harada, Hideo; Orchard, Michael J.; Nedachi, Munetomo

    2012-01-01

    The 34-million-year (My) interval of the Late Triassic is marked by the formation of several large impact structures on Earth. Late Triassic impact events have been considered a factor in biotic extinction events in the Late Triassic (e.g., end-Triassic extinction event), but this scenario remains controversial because of a lack of stratigraphic records of ejecta deposits. Here, we report evidence for an impact event (platinum group elements anomaly with nickel-rich magnetite and microspherules) from the middle Norian (Upper Triassic) deep-sea sediment in Japan. This includes anomalously high abundances of iridium, up to 41.5 parts per billion (ppb), in the ejecta deposit, which suggests that the iridium-enriched ejecta layers of the Late Triassic may be found on a global scale. The ejecta deposit is constrained by microfossils that suggest correlation with the 215.5-Mya, 100-km-wide Manicouagan impact crater in Canada. Our analysis of radiolarians shows no evidence of a mass extinction event across the impact event horizon, and no contemporaneous faunal turnover is seen in other marine planktons. However, such an event has been reported among marine faunas and terrestrial tetrapods and floras in North America. We, therefore, suggest that the Manicouagan impact triggered the extinction of terrestrial and marine organisms near the impact site but not within the pelagic marine realm. PMID:23129649

  8. Strontium isotope evolution of Late Permian and Triassic seawater

    NASA Astrophysics Data System (ADS)

    Korte, Christoph; Kozur, Heinz W.; Bruckschen, Peter; Veizer, Ján

    2003-01-01

    The 87Sr/ 86Sr values based on brachiopods and conodonts define a nearly continuous record for the Late Permian and Triassic intervals. Minor gaps in measurements exist only for the uppermost Brahmanian, lower part of the Upper Olenekian, and Middle Norian, and only sparse data are available for the Late Permian. These 219 measurements include 67 brachiopods and 114 conodont samples from the Tethyan realm as well as 37 brachiopods and one conodont sample from the mid-European Middle Triassic Muschelkalk Sea. The Late Permian/Lower Triassic interval is characterized by a steep 1.3 × 10 -3 rise, from 0.7070 at the base of the Dzhulfian to 0.7082 in the late Olenekian, a rate of change comparable to that in the Cenozoic. In the mid-Triassic (Anisian and Ladinian), the isotope values fall to 0.7075, followed again by a rise to 0.7081 in the Middle/Late Norian. The 87Sr/ 86Sr values decline again in the Late Norian (Sevatian) and Rhaetian to 0.7076. The sharp rise in the 87Sr/ 86Sr values during the Late Permian/Early Triassic was coincident with widespread clastic sedimentation. Because of the paucity of tectonic uplifts, the enhanced erosion may have been due to intermittent humid phases, during mainly an arid interval, coupled with the absence of a dense protective land plant cover following the mass extinction during the latest Permian. The apex of the 87Sr/ 86Sr curve at the Olenekian/Anisian boundary coincides with cessation of the large-scale clastic sedimentation and also marks the final recovery of land vegetation, as indicated by the renewed onset of coal formation in the Middle Triassic. The rising 87Sr/ 86Sr values from the Middle Carnian to the Late Norian coincide with the uplift and erosion of the Cimmeride-Indosinian orogens marking the closure of the Palaeotethys. The subsequent Rhaetian decline that continues into Jurassic (Pliensbachian/Toarcian boundary), on the other hand, coincides with the opening of the Vardar Ocean and its eastern continuation

  9. Permian-Triassic plutonism and tectonics, Death Valley region, California and Nevada

    SciTech Connect

    Snow, J.K.; Asmerom, Y. ); Lux, D.R. )

    1991-06-01

    Significant contractional structures that deform Permian rocks but predate an Early Triassic overlap sequence are recognized within the Cordilleran orogen, western US. Thrusting in the Death Valley region of the orogen, however, has been regarded as Middle Triassic or younger and thus kinematically distinct. The authors present new isotopic age limits on two posttectonic stocks that intrude major structures of the Death Valley thrust belt. The stocks are no younger than Middle Triassic, but are likely Late Permian in age, consistent with stratigraphic and structural data suggesting that thrusting predates the overlap sequence. The authors hypothesize that Permian shortening may have affected more than 700 km of the Cordilleran orogen at the same time arc activity began within cratonic North America but prior to Early Triassic emplacement of the structurally higher Sonomian arc terrane.

  10. Timing signatures of large scale solar eruptions

    NASA Astrophysics Data System (ADS)

    Balasubramaniam, K. S.; Hock-Mysliwiec, Rachel; Henry, Timothy; Kirk, Michael S.

    2016-05-01

    We examine the timing signatures of large solar eruptions resulting in flares, CMEs and Solar Energetic Particle events. We probe solar active regions from the chromosphere through the corona, using data from space and ground-based observations, including ISOON, SDO, GONG, and GOES. Our studies include a number of flares and CMEs of mostly the M- and X-strengths as categorized by GOES. We find that the chromospheric signatures of these large eruptions occur 5-30 minutes in advance of coronal high temperature signatures. These timing measurements are then used as inputs to models and reconstruct the eruptive nature of these systems, and explore their utility in forecasts.

  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

  12. 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

    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

  13. Paleosol formation during the Early Triassic Biotic Crisis in Norway

    NASA Astrophysics Data System (ADS)

    Knies, Jochen; Müller, Axel; Zwingmann, Horst; Fredin, Ola; Brönner, Marco; Viola, Giulio

    2016-04-01

    Fractured and kaolinite weathered basement rocks have been discovered in various wells off the Norwegian coast and inferences on timing, source to sink relationships, and environmental implications have been widely discussed. The reason for the kaolitinization has often been related to intensive chemical weathering during late Triassic to early Jurassic times. Chronological control has primarily been inferred from the overlying late Jurassic/early Cretaceous marine transgression and poorly constrained K-Ar datings from weathered basement onshore as well as climate conditions favourable for kaolinite formation. In this study, we present evidence that the deeply weathered basement off the mid-Norwegian coast represent a complete paleosol profile. Quartz geochemical fingerprinting indicate that transgressional marine inorganic sediments of late Jurassic age are derived from the paleosols. Whole-rock XRD analysis suggests characteristic mineral alteration zones topped with a kaolinite-Fe-oxyhyroxide zones composed of >80% kaolinite. Potassium feldspar is practically absent in the uppermost kaolinitic zones. Mass-balance changes show significant depletion-enrichment trends. Applying potassium/argon (K/Ar) geochronology on authigenic illite clay that grew in-situ at the time of paleosol formation reveals a early Triassic age (~250 Ma). The age corroborates with the Early Triassic biotic crisis and suggest a causal relationship between intense chemical weathering, high atmospheric CO2 concentration, extreme ocean warming, increased riverine flux of nutrients and widespread anoxia/euxinia on adjacent epicontinental seas.

  14. Pennsylvanian time scales and cycle periods

    SciTech Connect

    deV. Klein, G. )

    1990-05-01

    Geochronological results from central Europe indicate that the duration of Pennsylvanian time is only 19 m.y., compared to the Harland et al. and Palmer estimates of 34 m.y. Prior calculations of Pennsylvanian cycle periods from the midcontinent of North America suggesting a fit with Milankovitch orbital parameters may well be in errors; as a consequence, other mechanisms for possible eustatic sea-level changes represented in those cycles are needed. Calculation of cycle periods of 100 ka or less lack precision in stratigraphic intervals representing ages characterized by error margins of millions of years. Thus, cycle periods may be less reliable as an indicator of global process than previously considered, particularly in rocks of Paleozoic and early and middle Mesozoic age.

  15. Rapid evaluation of time scale using an optical clock

    NASA Astrophysics Data System (ADS)

    Ido, T.; Hachisu, H.; Nakagawa, F.; Hanado, Y.

    2016-06-01

    Feasibility of steering a time scale using an optical clock is investigated. Since the high stability of optical frequency standards enables rapid evaluation of the scale interval, the requirement for the continuous operation is mitigated. Numerical simulations with the input of real calibration data by a 87Sr lattice clock indicated that the calibrations once in two weeks maintain the time scale within 5 ns level using a currently available hydrogen maser at NICT. “Optical” steering of a time scale by the intermittent calibrations frees an optical frequency standard from being dedicated to the steering, enabling other applications using the same apparatus.

  16. Do quasars evolve over cosmological time scales?

    NASA Astrophysics Data System (ADS)

    Wampler, E. J.; Ponz, D.

    Systematic biases that are redshift dependent can influence the optical discovery of quasars and the evolution laws derived from counts of quasars. New data and their interpretation for quasars brighter than MB = -24 in the Palomar Bright Quasar Survey (BQS) (Schmidt and Green, 1983) are consistent with no evolution. A comparison of BQS quasars with the brightest quasars from the CTIO Schmidt Telescope Survey (Osmer and Smith, 1980) shows that if q(0) is near zero, the comoving density of bright quasars in a Friedmann cosmology is about 15 times higher for the CTIO survey quasars (mean z of about 2.8) than for the BQS quasars (mean z of about 1.8). In this case spectral evolution is also required since the CTIO quasars have stronger CIV 1548 A lines than the BQS quasars of similar luminosity. Alternatively, if q(0) is taken to be near 1, the CTIO survey quasars would then have a lower luminosity than the BQS quasars and these data would be consistent with no evolution. Strong CIV 1548 A lines for the CTIO quasars would then fit the general correlation between absolute quasar luminosity and emission line strength (Wampler, Gaskell, Burke and Baldwin, 1984).

  17. Triassic deformation of Permian Early Triassic arc-related sediments in the Beishan (NW China): Last pulse of the accretionary orogenesis in the southernmost Altaids

    NASA Astrophysics Data System (ADS)

    Tian, Zhonghua; Xiao, Wenjiao; Sun, Jimin; Windley, Brian F.; Glen, Richard; Han, Chunming; Zhang, Zhiyong; Zhang, Ji'en; Wan, Bo; Ao, Songjian; Song, Dongfang

    2015-11-01

    The Beishan orogenic collage (BOC) in the southernmost Altaids provides evidence of the final stage of evolution of the Paleo-Asian Ocean. However, the closure time of the Paleo-Asian Ocean in the BOC is controversial. From field mapping, and structural analysis of mesoscale, superposed folds in Early Triassic sediments in the Hongyanjing Basin in the central BOC, we define at least two phases of deformation, which we can bracket in age as end-Permian to Early-Late Triassic. The sandstones in the basin are poorly sorted with angular clasts, which indicates immaturity characteristic of proximal and rapid deposition. Geochemical data indicate that the Hongyanjing Basin probably developed in an arc-related setting near an active continental margin or mature island arc. Combined with published regional geological data, we interpret the Hongyanjing Basin as a Permian-Early Triassic inter-arc basin between the Carboniferous Mazongshan arc to the north and the Ordovician to Permian Huaniushan-Dundunshan arc to the south. In addition, the age distribution of our sediments shows that the active continental margin or continental arc on which the Hongyanjing arc-related basin sat was somehow independently distributed in the Paleo-Asian Ocean without any major contribution of provenance from the Tarim Craton and Dunhuang Block to the south and Southern Mongolia accretionary system to the north. Deformation of the superposed folds began in the end-Permian, continued in the Early Triassic, and ended before the middle Late Triassic (219 Ma). Therefore the accretionary orogenesis in the Beishan part of the southernmost Altaids was still ongoing in the early to middle Triassic, and it finished in the Late Triassic, which might have been the last pulse of the accretionary orogenesis in the southernmost Altaids. We correlate this terminal event with tectonic developments in the Kunlun and Qinling orogens in the Tethyan domain.

  18. Critical time scale of coarse-graining entropy production

    NASA Astrophysics Data System (ADS)

    Sohn, Jang-il

    2016-04-01

    We study coarse-grained entropy production in an asymmetric random walk system on a periodic one-dimensional lattice. In coarse-grained systems, the original dynamics are unavoidably destroyed, but the coarse-grained entropy production is not hidden below the critical time-scale separation. The hidden entropy production is rapidly increasing near the critical time-scale separation.

  19. Stratigraphy and correlation of Upper Triassic strata between west Texas and eastern New Mexico

    SciTech Connect

    Lucas, S.G. ); Anderson, O.J. )

    1992-04-01

    Lithostratigraphy and vertebrate biochronology allow precise correlation of Upper Triassic strata between west Texas and eastern New Mexico. Upper Triassic strata are well exposed in west Texas from Oldham to Scurry counties, and are assigned to the Dockum Formation of the Chinle Group. Fossil vertebrates from the Camp Springs and Tecovas Members are of late Carnian age, whereas those from the Copper Member are of early Norian age. Upper Triassic strata in east-central New Mexico, across the Llano Estacado from the west Texas outcrops, correlate as follows: Camper Springs = lower Santa Rose; Tecovas = upper Santa Rosa/Garita Creek; Trujillo = Trujillo ('Cuervo'); Cooper = lower Bull Canyon. Upper Triassic strata in southeastern New Mexico and in Howard and adjacent counties in Texas are the lower Santa Rosa/Camper Springs overlain by mudstones and sandstones that contain late Carnian vertebrates and are informally termed upper member of Dockum Formation. Available data refute several long-held ideas about the Upper Triassic of west Texas. These data demonstrate that: (1) there is a pervasive unconformity at the base of the Dockum Formation that represents much of Triassic time; (2) the Trujillo Member is not correlative with the Santa Rosa of eastern New Mexico: Trujillo is a medial Dockum unit, whereas Santa Rosa is at the base of the Upper Triassic section; (3) very little Dockum mudrock was deposited in lakes; and (4) Dockum rivers flowed almost exclusively to the north, northwest, and west, so there was no closed depositional basin in west Texas during the Late Triassic.

  20. Trophic network models explain instability of Early Triassic terrestrial communities

    PubMed Central

    Roopnarine, Peter D; Angielczyk, Kenneth D; Wang, Steve C; Hertog, Rachel

    2007-01-01

    Studies of the end-Permian mass extinction have emphasized potential abiotic causes and their direct biotic effects. Less attention has been devoted to secondary extinctions resulting from ecological crises and the effect of community structure on such extinctions. Here we use a trophic network model that combines topological and dynamic approaches to simulate disruptions of primary productivity in palaeocommunities. We apply the model to Permian and Triassic communities of the Karoo Basin, South Africa, and show that while Permian communities bear no evidence of being especially susceptible to extinction, Early Triassic communities appear to have been inherently less stable. Much of the instability results from the faster post-extinction diversification of amphibian guilds relative to amniotes. The resulting communities differed fundamentally in structure from their Permian predecessors. Additionally, our results imply that changing community structures over time may explain long-term trends like declining rates of Phanerozoic background extinction PMID:17609191

  1. Evolutionary time-scale of primate bocaviruses.

    PubMed

    Babkin, Igor V; Tyumentsev, Alexander I; Tikunov, Artem Yu; Kurilshikov, Alexander M; Ryabchikova, Elena I; Zhirakovskaya, Elena V; Netesov, Sergei V; Tikunova, Nina V

    2013-03-01

    Human bocavirus (HBoV) is associated with acute gastroenteritis in humans, occurring mostly in young children and elderly people. Four bocavirus genotypes (HBoV1-HBoV4) have been found so far. Since there were no data on the contribution of HBoV to gastroenteritis in Russia, 1781 fecal samples collected from infants hospitalized with acute gastroenteritis in Novosibirsk, Russia during one year were tested for the presence of nucleic acids from HBoV and three major gastrointestinal viruses (rotavirus A, norovirus II, and astrovirus). HBoV was detected only in 1.9% of the samples: HBoV1 was detected in 0.6% and HBoV2, in 1.3%. Complete genome sequencing of three Novosibirsk isolates was performed. An evolutionary analysis of these sequences and the available sequences of human and great apes bocaviruses demonstrated that the current HBoV genotypes diverged comparatively recently, about 60-300years ago. The independent evolution of bocaviruses from chimpanzees and gorillas commenced at the same time period. This suggests that these isolates of great apes bocaviruses belong to separate genotypes within the species of human bocavirus, which is actually the primate bocavirus. The rate of mutation accumulation in the genome of primate bocaviruses has been estimated as approximately 9×10(-4)substitutions/site/year. It has been demonstrated that HBoV1 diverged from the ancestor common with chimpanzee bocavirus approximately 60-80years ago, while HBoV4 separated from great apes bocaviruses about 200-300years ago. The hypothesis postulating independent evolution of HBoV1 and HBoV4 genotypes from primate bocaviruses has been proposed. PMID:23313830

  2. 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.

  3. Severest crisis overlooked-Worst disruption of terrestrial environments postdates the Permian-Triassic mass extinction.

    PubMed

    Hochuli, Peter A; Sanson-Barrera, Anna; Schneebeli-Hermann, Elke; Bucher, Hugo

    2016-01-01

    Generally Early Triassic floras are believed to be depauperate, suffering from protracted recovery following the Permian-Triassic extinction event. Here we present palynological data of an expanded East Greenland section documenting recovered floras in the basal Triassic (Griesbachian) and a subsequent fundamental floral turnover, postdating the Permian-Triassic boundary extinction by about 500 kyrs. This event is marked by a swap in dominating floral elements, changing from gymnosperm pollen-dominated associations in the Griesbachian to lycopsid spore-dominated assemblages in the Dienerian. This turnover coincides with an extreme δ(13)Corg negative shift revealing a severe environmental crisis, probably induced by volcanic outbursts of the Siberian Traps, accompanied by a climatic turnover, changing from cool and dry in the Griesbachian to hot and humid in the Dienerian. Estimates of sedimentation rates suggest that this environmental alteration took place within some 1000 years. Similar, coeval changes documented on the North Indian Margin (Pakistan) and the Bowen Basin (Australia) indicate the global extent of this crisis. Our results evidence the first profound disruption of the recovery of terrestrial environments about 500kyrs after the Permian-Triassic extinction event. It was followed by another crisis, about 1myrs later thus, the Early Triassic can be characterised as a time of successive environmental crises. PMID:27340926

  4. Severest crisis overlooked—Worst disruption of terrestrial environments postdates the Permian–Triassic mass extinction

    PubMed Central

    Hochuli, Peter A.; Sanson-Barrera, Anna; Schneebeli-Hermann, Elke; Bucher, Hugo

    2016-01-01

    Generally Early Triassic floras are believed to be depauperate, suffering from protracted recovery following the Permian–Triassic extinction event. Here we present palynological data of an expanded East Greenland section documenting recovered floras in the basal Triassic (Griesbachian) and a subsequent fundamental floral turnover, postdating the Permian–Triassic boundary extinction by about 500 kyrs. This event is marked by a swap in dominating floral elements, changing from gymnosperm pollen-dominated associations in the Griesbachian to lycopsid spore-dominated assemblages in the Dienerian. This turnover coincides with an extreme δ13Corg negative shift revealing a severe environmental crisis, probably induced by volcanic outbursts of the Siberian Traps, accompanied by a climatic turnover, changing from cool and dry in the Griesbachian to hot and humid in the Dienerian. Estimates of sedimentation rates suggest that this environmental alteration took place within some 1000 years. Similar, coeval changes documented on the North Indian Margin (Pakistan) and the Bowen Basin (Australia) indicate the global extent of this crisis. Our results evidence the first profound disruption of the recovery of terrestrial environments about 500kyrs after the Permian–Triassic extinction event. It was followed by another crisis, about 1myrs later thus, the Early Triassic can be characterised as a time of successive environmental crises. PMID:27340926

  5. Organic geochemical characterization of the Lower-Middle Triassic sedimentary rocks from south China

    NASA Astrophysics Data System (ADS)

    Saito, R.

    2015-12-01

    The most devastated environments and depleted biodiversity on Earth occurred during the Early Triassic epoch following the latest Permian mass extinction. Complete biotic recovery, characterized by a return to pre-extinction diversity levels, took an extraordinarily long time (ca. 5 x 106 yr), probably because harsh conditions developed repeatedly during the Early Triassic. Newly obtained organic geochemistry data from south China area, indicated a variety of biotic (eukaryotic algae, cyanobacteria, bacteria, and archaea) and environmental fluctuations (redox) during the Early Triassic. Remarkably, some sedimentary rocks from Lower Triassic strata contain rare biomarkers such as biphytanes and okenane, whch are biomarkers for archaea and purple sulfur bacteria, respectively. This is the first study to describe in detail primary producers, microbes, and redox conditions in the Early-Early Middle Triassic, on the basis of biomarkers such as steranes, 2-methyl hopanes, hopanes, biphytanes, regular isoprenoids, n-alkanes, okenane, chlorobactane, β-carotane, and γ-carotane. The results greatly not only increase our understanding of the recovery processes that occurred following the Permian mass extinction, but also emphasize an effectiveness of organic geochemistry against the Early Triassic.

  6. Severest crisis overlooked—Worst disruption of terrestrial environments postdates the Permian–Triassic mass extinction

    NASA Astrophysics Data System (ADS)

    Hochuli, Peter A.; Sanson-Barrera, Anna; Schneebeli-Hermann, Elke; Bucher, Hugo

    2016-06-01

    Generally Early Triassic floras are believed to be depauperate, suffering from protracted recovery following the Permian–Triassic extinction event. Here we present palynological data of an expanded East Greenland section documenting recovered floras in the basal Triassic (Griesbachian) and a subsequent fundamental floral turnover, postdating the Permian–Triassic boundary extinction by about 500 kyrs. This event is marked by a swap in dominating floral elements, changing from gymnosperm pollen-dominated associations in the Griesbachian to lycopsid spore-dominated assemblages in the Dienerian. This turnover coincides with an extreme δ13Corg negative shift revealing a severe environmental crisis, probably induced by volcanic outbursts of the Siberian Traps, accompanied by a climatic turnover, changing from cool and dry in the Griesbachian to hot and humid in the Dienerian. Estimates of sedimentation rates suggest that this environmental alteration took place within some 1000 years. Similar, coeval changes documented on the North Indian Margin (Pakistan) and the Bowen Basin (Australia) indicate the global extent of this crisis. Our results evidence the first profound disruption of the recovery of terrestrial environments about 500kyrs after the Permian–Triassic extinction event. It was followed by another crisis, about 1myrs later thus, the Early Triassic can be characterised as a time of successive environmental crises.

  7. 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.

  8. 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

  9. 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.

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

    PubMed

    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 ((187)Os/(188)Osi) 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 (187)Os/(188)Os ratios in the Late Triassic. PMID:24036603

  11. 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

  12. 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

  13. 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

  14. Liquidity Spillover in International Stock Markets through Distinct Time Scales

    PubMed Central

    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

  15. 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

  16. Space and Time Scale Variability and Interdependencies in Hydrological Processes

    NASA Astrophysics Data System (ADS)

    Feddes, Reinder A.

    1995-09-01

    The atmospheric, hydrologic, and terrestrial components of the earth's systems operate on different time and space scales. Resolving these scaling incongruities as well as understanding and modeling the complex interaction of land surface processes at the different scales represents a major challenge for hydrologists, ecologists and meteorologists alike. This book presents the contributions of hydrologists, meteorologists, and ecologists to the first IHP/IAHS George Kovacs Colloqium on global hydrology and climate change. It deals with time and space scale variations with reference to several topics including soil water balance, ecosystems and interaction of flow systems, and macroscale hydrologic modeling. This book will be of great use to researchers, engineers and forecasters with an interest in space and time scale variability.

  17. Milankovitch and sub-Milankovitch cycles of the Early Triassic Daye Formation, South China and their geochronological and paleoclimatic implications

    NASA Astrophysics Data System (ADS)

    Wu, H.; Zhang, S.; Feng, Q.; Jiang, G.; Li, H.; Yang, T.

    2011-12-01

    the Induan stage is 1.162 Ma, with the Griesbachian and Dienerian substage of 491ka and 671 ka, respectively. The new astronomical time scale also provides time constraints for the conodont and bivalve biozones, the carbonate carbon isotope (δ13C) records and magnetic polarity zones of the Lower Triassic Daye Formation. Time constraints for the conodont biozones include 34 ka for Hindeodus parvus , 24 ka for Isarcicella stachei-I. isarcica, 367 ka for Neogondolella planate-Ng. carinata, 66 ka for Neogondolella discreta, 255 ka for Neospathodus kummeli and 416 ka for Neospathodus dieneri. The Early Smithian negative δ13C shift near the Indun/Olenekian boundary may have happened within 430 ka. Global comparison indicates that Milankovitch and 4-5 ka sub-Milankovitch forcing depositional rhythms may have been common in tropical and sub-tropical carbonate platforms during Early and Middle Triassic time. The ultimate control on the 4-5 ka cycles may have been millennial-scale fluctuations in solar insolation.

  18. 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

  19. NEA Scout Solar Sail: Half-scale Fold Time Lapse

    NASA Video Gallery

    In this time lapse, the Near-Earth Asteroid Scout (NEA Scout) CubeSat team rolls a half-scale prototype of the small satellite's solar sail in preparation for a deployment test. During its mission,...

  20. Kibble-Zurek mechanism and finite-time scaling

    NASA Astrophysics Data System (ADS)

    Huang, Yingyi; Yin, Shuai; Feng, Baoquan; Zhong, Fan

    2014-10-01

    The Kibble-Zurek (KZ) mechanism has been applied to a variety of systems ranging from low-temperature Bose-Einstein condensations to grand unification scales in particle physics and cosmology and from classical phase transitions to quantum phase transitions. Here, we show that finite-time scaling (FTS) provides a detailed improved understanding of the mechanism. In particular, the finite time scale, which is introduced by the external driving (or quenching) and results in FTS, is the origin of the division of the adiabatic regimes from the impulse regime in the KZ mechanism. The origin of the KZ scaling for the defect density, generated during the driving through a critical point, is not that the correlation length ceases growing in the nonadiabatic impulse regime, but rather, is that it is taken over by the effective finite length scale corresponding to the finite time scale. We also show that FTS accounts well for and improves the scaling ansatz proposed recently by Liu, Polkovnikov, and Sandvik, [Phys. Rev. B 89, 054307 (2014), 10.1103/PhysRevB.89.054307]. Further, we show that their universal power-law scaling form applies only to some observables in cooling but not to heating. Even in cooling, it is invalid either when an appropriate external field is present. However, this finite-time-finite-size scaling calls for caution in application of FTS. Detailed scaling behaviors of the FTS and finite-size scaling, along with their crossover, are explicitly demonstrated, with the dynamic critical exponent z being estimated for two- and three-dimensional Ising models under the usual Metropolis dynamics. These values of z are found to give rise to better data collapses than the extant values do in most cases but take on different values in heating and cooling in both two- and three-dimensional spaces.

  1. 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.

  2. Time scale for point-defect equilibration in nanostructures

    SciTech Connect

    Millett, Paul C.; Wolf, Dieter; Desai, Tapan; Yamakov, Vesselin

    2008-10-20

    Molecular dynamics simulations of high-temperature annealing are performed on nanostructured materials enabling direct observation of vacancy emission from planar defects (i.e., grain boundaries and free surfaces) to populate the initially vacancy-free grain interiors on a subnanosecond time scale. We demonstrate a universal time-length scale correlation that governs these re-equilibration processes, suggesting that nanostructures are particularly stable against perturbations in their point-defect concentrations, caused for example by particle irradiation or temperature fluctuations.

  3. Scale-dependent intrinsic entropies of complex time series.

    PubMed

    Yeh, Jia-Rong; Peng, Chung-Kang; Huang, Norden E

    2016-04-13

    Multi-scale entropy (MSE) was developed as a measure of complexity for complex time series, and it has been applied widely in recent years. The MSE algorithm is based on the assumption that biological systems possess the ability to adapt and function in an ever-changing environment, and these systems need to operate across multiple temporal and spatial scales, such that their complexity is also multi-scale and hierarchical. Here, we present a systematic approach to apply the empirical mode decomposition algorithm, which can detrend time series on various time scales, prior to analysing a signal's complexity by measuring the irregularity of its dynamics on multiple time scales. Simulated time series of fractal Gaussian noise and human heartbeat time series were used to study the performance of this new approach. We show that our method can successfully quantify the fractal properties of the simulated time series and can accurately distinguish modulations in human heartbeat time series in health and disease. PMID:26953181

  4. Russian national time scale long-term stability

    NASA Technical Reports Server (NTRS)

    Alshina, A. P.; Gaigerov, B. A.; Koshelyaevsky, N. B.; Pushkin, S. B.

    1994-01-01

    The Institute of Metrology for Time and Space NPO 'VNIIFTRI' generates the National Time Scale (NTS) of Russia -- one of the most stable time scales in the world. Its striking feature is that it is based on a free ensemble of H-masers only. During last two years the estimations of NTS longterm stability based only on H-maser intercomparison data gives a flicker floor of about (2 to 3) x 10(exp -15) for averaging times from 1 day to 1 month. Perhaps the most significant feature for a time laboratory is an extremely low possible frequency drift -- it is too difficult to estimate it reliably. The other estimations, free from possible inside the ensemble correlation phenomena, are available based on the time comparison of NTS relative to the stable enough time scale of outer laboratories. The data on NTS comparison relative to the time scale of secondary time and frequency standards at Golitzino and Irkutsk in Russia and relative to NIST, PTB and USNO using GLONASS and GPS time transfer links gives stability estimations which are close to that based on H-maser intercomparisons.

  5. 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.

  6. 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

  7. Trends in Surface Radiation Budgets at Climatic Time Scales

    NASA Astrophysics Data System (ADS)

    Pinker, R. T.; Zhang, B.; Ma, Y.

    2015-12-01

    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 radiative balance at global scale, however, the length of available satellite records is limited due to the frequent changes in the observing systems. In this paper we report on an effort to synthesize satellite observations from independent sources to estimates shortwave and longwave surface radiative fluxes at climatic time scales and use them to learn about their variability and trends at global scale with a focus on the tropics. An attempt will be made to learn from the comparison about possible causes of observed 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 updated knowledge on radiative balance as compared to what is known from shorter time records.

  8. Biogeography of Triassic tetrapods: evidence for provincialism and driven sympatric cladogenesis in the early evolution of modern tetrapod lineages.

    PubMed

    Ezcurra, Martin D

    2010-08-22

    Triassic tetrapods are of key importance in understanding their evolutionary history, because several tetrapod clades, including most of their modern lineages, first appeared or experienced their initial evolutionary radiation during this Period. In order to test previous palaeobiogeographical hypotheses of Triassic tetrapod faunas, tree reconciliation analyses (TRA) were performed with the aim of recovering biogeographical patterns based on phylogenetic signals provided by a composite tree of Middle and Late Triassic tetrapods. The TRA found significant evidence for the presence of different palaeobiogeographical patterns during the analysed time spans. First, a Pangaean distribution is observed during the Middle Triassic, in which several cosmopolitan tetrapod groups are found. During the early Late Triassic a strongly palaeolatitudinally influenced pattern is recovered, with some tetrapod lineages restricted to palaeolatitudinal belts. During the latest Triassic, Gondwanan territories were more closely related to each other than to Laurasian ones, with a distinct tetrapod fauna at low palaeolatitudes. Finally, more than 75 per cent of the cladogenetic events recorded in the tetrapod phylogeny occurred as sympatric splits or within-area vicariance, indicating that evolutionary processes at the regional level were the main drivers in the radiation of Middle and Late Triassic tetrapods and the early evolution of several modern tetrapod lineages. PMID:20392730

  9. Time scale construction from multiple sources of information (Invited)

    NASA Astrophysics Data System (ADS)

    Malinverno, A.

    2013-12-01

    Geological age estimates are provided by diverse chronometers, such as radiometric measurements, astrochronology, and the spacing of magnetic anomalies recorded on mid-ocean ridges by seafloor spreading. These age estimates are affected by errors that can be systematic (e.g., biased radiometric dates due to imperfect assumptions) or random (e.g., imprecise recording of astronomical cycles in sedimentary records). Whereas systematic errors can be reduced by improvements in technique and calibration, uncertainties due to random errors will always be present and need to be dealt with. A Bayesian framework can be used to construct an integrated time scale that is based on several uncertain sources of information. In this framework, each piece of data and the final time scale have an associated probability distribution that describes their uncertainty. The key calculation is to determine the uncertainty in the time scale from the uncertain data that constrain it. In practice, this calculation can be performed by Monte Carlo sampling. In Markov chain Monte Carlo algorithms, the time scale is iteratively perturbed and the perturbed time scale is accepted or rejected depending on how closely it fits the data. The final result is a large ensemble of possible time scales that are consistent with all the uncertain data; while the average of this ensemble defines a 'best' time scale, the ensemble variability quantifies the time scale uncertainty. An example of this approach is the M-sequence (Late Jurassic-Early Cretaceous, ~160-120 Ma) MHTC12 geomagnetic polarity time scale (GPTS) of Malinverno et al. (2012, J. Geophys. Res., B06104, doi:10.1029/2012JB009260). Previous GPTSs were constructed by interpolating between dated marine magnetic anomalies while assuming constant or smoothly varying spreading rates. These GPTSs were typically based on magnetic lineations from one or a few selected spreading centers, and an undesirable result is that they imply larger spreading rate

  10. 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.

  11. Scaling properties in time-varying networks with memory

    NASA Astrophysics Data System (ADS)

    Kim, Hyewon; Ha, Meesoon; Jeong, Hawoong

    2015-12-01

    The formation of network structure is mainly influenced by an individual node's activity and its memory, where activity can usually be interpreted as the individual inherent property and memory can be represented by the interaction strength between nodes. In our study, we define the activity through the appearance pattern in the time-aggregated network representation, and quantify the memory through the contact pattern of empirical temporal networks. To address the role of activity and memory in epidemics on time-varying networks, we propose temporal-pattern coarsening of activity-driven growing networks with memory. In particular, we focus on the relation between time-scale coarsening and spreading dynamics in the context of dynamic scaling and finite-size scaling. Finally, we discuss the universality issue of spreading dynamics on time-varying networks for various memory-causality tests.

  12. 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.

  13. Thermodynamics Constrains Allometric Scaling of Optimal Development Time in Insects

    PubMed Central

    Dillon, Michael E.; Frazier, Melanie R.

    2013-01-01

    Development time is a critical life-history trait that has profound effects on organism fitness and on population growth rates. For ectotherms, development time is strongly influenced by temperature and is predicted to scale with body mass to the quarter power based on 1) the ontogenetic growth model of the metabolic theory of ecology which describes a bioenergetic balance between tissue maintenance and growth given the scaling relationship between metabolism and body size, and 2) numerous studies, primarily of vertebrate endotherms, that largely support this prediction. However, few studies have investigated the allometry of development time among invertebrates, including insects. Abundant data on development of diverse insects provides an ideal opportunity to better understand the scaling of development time in this ecologically and economically important group. Insects develop more quickly at warmer temperatures until reaching a minimum development time at some optimal temperature, after which development slows. We evaluated the allometry of insect development time by compiling estimates of minimum development time and optimal developmental temperature for 361 insect species from 16 orders with body mass varying over nearly 6 orders of magnitude. Allometric scaling exponents varied with the statistical approach: standardized major axis regression supported the predicted quarter-power scaling relationship, but ordinary and phylogenetic generalized least squares did not. Regardless of the statistical approach, body size alone explained less than 28% of the variation in development time. Models that also included optimal temperature explained over 50% of the variation in development time. Warm-adapted insects developed more quickly, regardless of body size, supporting the “hotter is better” hypothesis that posits that ectotherms have a limited ability to evolutionarily compensate for the depressing effects of low temperatures on rates of biological processes

  14. Deviations from uniform power law scaling in nonstationary time series

    NASA Technical Reports Server (NTRS)

    Viswanathan, G. M.; Peng, C. K.; Stanley, H. E.; Goldberger, A. L.

    1997-01-01

    A classic problem in physics is the analysis of highly nonstationary time series that typically exhibit long-range correlations. Here we test the hypothesis that the scaling properties of the dynamics of healthy physiological systems are more stable than those of pathological systems by studying beat-to-beat fluctuations in the human heart rate. We develop techniques based on the Fano factor and Allan factor functions, as well as on detrended fluctuation analysis, for quantifying deviations from uniform power-law scaling in nonstationary time series. By analyzing extremely long data sets of up to N = 10(5) beats for 11 healthy subjects, we find that the fluctuations in the heart rate scale approximately uniformly over several temporal orders of magnitude. By contrast, we find that in data sets of comparable length for 14 subjects with heart disease, the fluctuations grow erratically, indicating a loss of scaling stability.

  15. Physics in space-time with scale-dependent metrics

    NASA Astrophysics Data System (ADS)

    Balankin, Alexander S.

    2013-10-01

    We construct three-dimensional space Rγ3 with the scale-dependent metric and the corresponding Minkowski space-time Mγ,β4 with the scale-dependent fractal (DH) and spectral (DS) dimensions. The local derivatives based on scale-dependent metrics are defined and differential vector calculus in Rγ3 is developed. We state that Mγ,β4 provides a unified phenomenological framework for dimensional flow observed in quite different models of quantum gravity. Nevertheless, the main attention is focused on the special case of flat space-time M1/3,14 with the scale-dependent Cantor-dust-like distribution of admissible states, such that DH increases from DH=2 on the scale ≪ℓ0 to DH=4 in the infrared limit ≫ℓ0, where ℓ0 is the characteristic length (e.g. the Planck length, or characteristic size of multi-fractal features in heterogeneous medium), whereas DS≡4 in all scales. Possible applications of approach based on the scale-dependent metric to systems of different nature are briefly discussed.

  16. Inferring synaptic structure in presence of neural interaction time scales.

    PubMed

    Capone, Cristiano; Filosa, Carla; Gigante, Guido; Ricci-Tersenghi, Federico; Del Giudice, Paolo

    2015-01-01

    Biological networks display a variety of activity patterns reflecting a web of interactions that is complex both in space and time. Yet inference methods have mainly focused on reconstructing, from the network's activity, the spatial structure, by assuming equilibrium conditions or, more recently, a probabilistic dynamics with a single arbitrary time-step. Here we show that, under this latter assumption, the inference procedure fails to reconstruct the synaptic matrix of a network of integrate-and-fire neurons when the chosen time scale of interaction does not closely match the synaptic delay or when no single time scale for the interaction can be identified; such failure, moreover, exposes a distinctive bias of the inference method that can lead to infer as inhibitory the excitatory synapses with interaction time scales longer than the model's time-step. We therefore introduce a new two-step method, that first infers through cross-correlation profiles the delay-structure of the network and then reconstructs the synaptic matrix, and successfully test it on networks with different topologies and in different activity regimes. Although step one is able to accurately recover the delay-structure of the network, thus getting rid of any a priori guess about the time scales of the interaction, the inference method introduces nonetheless an arbitrary time scale, the time-bin dt used to binarize the spike trains. We therefore analytically and numerically study how the choice of dt affects the inference in our network model, finding that the relationship between the inferred couplings and the real synaptic efficacies, albeit being quadratic in both cases, depends critically on dt for the excitatory synapses only, whilst being basically independent of it for the inhibitory ones. PMID:25807389

  17. 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

  18. A methane-based time scale for Vostok ice

    NASA Astrophysics Data System (ADS)

    Ruddiman, William F.; Raymo, Maureen E.

    2003-02-01

    Tuning the Vostok methane signal to mid-July 30°N insolation yields a new ice-core gas time scale. This exercise has two rationales: (1) evidence supporting Kutzbach's theory that low-latitude summer insolation in the northern hemisphere controls the strength of tropical monsoons, and (2) interhemispheric CH 4 gradients showing that the main control of orbital-scale CH 4 variations is tropical (monsoonal) sources. The immediate basis for tuning CH 4 to mid-July insolation is the coincident timing of the most recent (pre-anthropogenic) CH 4 maximum at 11,000-10,500 calendar years ago and the most recent July 30°N insolation maximum (all ages in this paper are in calendar years unless specified as 14C years). The resulting CH 4 gas time scale diverges by as much as 15,000 years from the GT4 gas time scale (Petit et al., Nature 399 (1999) 429) prior to 250,000 years ago, but it matches fairly closely a time scale derived by tuning ice-core δ18O atm to a lagged insolation signal (Shackleton, Science 289 (2000) 1897). Most offsets between the CH 4 and δ18O atm time scales can be explained by assuming that tropical monsoons and ice sheets alternate in controlling the phase of the δ18O atm signal. The CH 4 time scale provides an estimate of the timing of the Vostok CO 2 signal against SPECMAP marine δ18O, often used as an index of global ice volume. On the CH 4 time scale, all CO 2 responses are highly coherent with SPECMAP δ18O at the orbital periods. CO 2 leads δ18O by 5000 years at 100,000 years (eccentricity), but the two signals are nearly in-phase at 41,000 years (obliquity) and 23,000 years (precession). The actual phasing between CO 2 and ice volume is difficult to infer because of likely SST overprints on the SPECMAP δ18O signal. CO 2 could lead, or be in phase with, ice volume, but is unlikely to lag behind the ice response.

  19. 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.

  20. Segregation time-scales in model granular flows

    NASA Astrophysics Data System (ADS)

    Staron, Lydie; Phillips, Jeremy C.

    2016-04-01

    Segregation patterns in natural granular systems offer a singular picture of the systems evolution. In many cases, understanding segregation dynamics may help understanding the system's history as well as its future evolution. Among the key questions, one concerns the typical time-scales at which segregation occurs. In this contribution, we present model granular flows simulated by means of the discrete Contact Dynamics method. The granular flows are bi-disperse, namely exhibiting two grain sizes. The flow composition and its dynamics are systematically varied, and the segregation dynamics carefully analyzed. We propose a physical model for the segregation that gives account of the observed dependence of segregation time scales on composition and dynamics. References L. Staron and J. C. Phillips, Stress partition and micro-structure in size-segregating granular flows, Phys. Rev. E 92 022210 (2015) L. Staron and J. C. Phillips, Segregation time-scales in bi-disperse granular flows, Phys. Fluids 26 (3), 033302 (2014)

  1. 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.

  2. Evaluation of Scaling Invariance Embedded in Short Time Series

    PubMed Central

    Pan, Xue; Hou, Lei; Stephen, Mutua; Yang, Huijie; Zhu, Chenping

    2014-01-01

    Scaling invariance of time series has been making great contributions in diverse research fields. But how to evaluate scaling exponent from a real-world series is still an open problem. Finite length of time series may induce unacceptable fluctuation and bias to statistical quantities and consequent invalidation of currently used standard methods. In this paper a new concept called correlation-dependent balanced estimation of diffusion entropy is developed to evaluate scale-invariance in very short time series with length . Calculations with specified Hurst exponent values of show that by using the standard central moving average de-trending procedure this method can evaluate the scaling exponents for short time series with ignorable bias () and sharp confidential interval (standard deviation ). Considering the stride series from ten volunteers along an approximate oval path of a specified length, we observe that though the averages and deviations of scaling exponents are close, their evolutionary behaviors display rich patterns. It has potential use in analyzing physiological signals, detecting early warning signals, and so on. As an emphasis, the our core contribution is that by means of the proposed method one can estimate precisely shannon entropy from limited records. PMID:25549356

  3. Going up in time and length scales in modeling polymers

    NASA Astrophysics Data System (ADS)

    Grest, Gary S.

    Polymer properties depend on a wide range of coupled length and time scales, with unique macroscopic viscoelastic behavior stemming from interactions at the atomistic level. The need to probe polymers across time and length scales and particularly computational modeling is inherently challenging. Here new paths to probing long time and length scales including introducing interactions into traditional bead-spring models and coarse graining of atomistic simulations will be compared and discussed. Using linear polyethylene as a model system, the degree of coarse graining with two to six methylene groups per coarse-grained bead derived from a fully atomistic melt simulation were probed. We show that the degree of coarse graining affects the measured dynamic. Using these models we were successful in probing highly entangled melts and were able reach the long-time diffusive regime which is computationally inaccessible using atomistic simulations. We simulated the relaxation modulus and shear viscosity of well-entangled polyethylene melts for scaled times of 500 µs. Results for plateau modulus are in good agreement with experiment. The long time and length scale is coupled to the macroscopic viscoelasticity where the degree of coarse graining sets the minimum length scale instrumental in defining polymer properties and dynamics. Results will be compared to those obtained from simple bead-spring models to demonstrate the additional insight that can be gained from atomistically inspired coarse grained models. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  4. Time scales for molecule formation by ion-molecule reactions

    NASA Technical Reports Server (NTRS)

    Langer, W. D.; Glassgold, A. E.

    1976-01-01

    Analytical solutions are obtained for nonlinear differential equations governing the time-dependence of molecular abundances in interstellar clouds. Three gas-phase reaction schemes are considered separately for the regions where each dominates. The particular case of CO, and closely related members of the Oh and CH families of molecules, is studied for given values of temperature, density, and the radiation field. Nonlinear effects and couplings with particular ions are found to be important. The time scales for CO formation range from 100,000 to a few million years, depending on the chemistry and regime. The time required for essentially complete conversion of C(+) to CO in the region where the H3(+) chemistry dominates is several million years. Because this time is longer than or comparable to dynamical time scales for dense interstellar clouds, steady-state abundances may not be observed in such clouds.

  5. Time scales of crystal mixing in magma mushes

    NASA Astrophysics Data System (ADS)

    Schleicher, Jillian M.; Bergantz, George W.; Breidenthal, Robert E.; Burgisser, Alain

    2016-02-01

    Magma mixing is widely recognized as a means of producing compositional diversity and preconditioning magmas for eruption. However, the processes and associated time scales that produce the commonly observed expressions of magma mixing are poorly understood, especially under crystal-rich conditions. Here we introduce and exemplify a parameterized method to predict the characteristic mixing time of crystals in a crystal-rich magma mush that is subject to open-system reintrusion events. Our approach includes novel numerical simulations that resolve multiphase particle-fluid interactions. It also quantifies the crystal mixing by calculating both the local and system-wide progressive loss of the spatial correlation of individual crystals throughout the mixing region. Both inertial and viscous time scales for bulk mixing are introduced. Estimated mixing times are compared to natural examples and the time for basaltic mush systems to become well mixed can be on the order of 10 days.

  6. High precipitation rate in a Middle Triassic carbonate platform: Implications on the relationship between seawater saturation state and carbonate production

    NASA Astrophysics Data System (ADS)

    Franceschi, Marco; Preto, Nereo; Marangon, Alessandro; Gattolin, Giovanni; Meda, Marco

    2016-06-01

    Three-dimensional geological modeling of the Middle Triassic Latemar carbonate platform is coupled with facies modal analysis to estimate its carbonate precipitation rate (G). The 3D model, strongly constrained by field data, encompasses a specific stratigraphic interval of the platform, bounded by two isochronous surfaces. Modal analysis of thin sections allows estimating the proportion of syndepositional vs postdepositional carbonate in the facies associations of the platform. This, together with the 3D facies distribution in the model that takes into account lateral and vertical facies variability, permits to calculate the volumes of syndepositional carbonate preserved at Latemar between the two considered isochrones. Given the peculiar characteristics of the platform, that does not show evidences of strong dissolution processes or large carbonate mass loss through export in the nearby basins, results can be used to estimate the average precipitation rate of the platform in the considered time interval. This estimate allows discussion in relation to models of ocean water saturation state (Ω) with respect to carbonates in the geological past, and comparison to the calculated precipitation rates of modern tropical coral reef ecosystems at global and reef scale. A high G value is found at Latemar and represents the first empirical confirmation that, in the Triassic, extremes in Ω may have triggered high carbonate precipitation in shallow water settings; moreover, comparison to modern reefs points to a possible common relationship that may link seawater Ω and precipitation rate in carbonate platform ecosystems through geological time.

  7. Dynamics symmetries of Hamiltonian system on time scales

    SciTech Connect

    Peng, Keke Luo, Yiping

    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.

  8. Examination of hypotheses for the Permo-Triassic boundary extinction by carbon cycle modeling.

    PubMed

    Berner, Robert A

    2002-04-01

    The biological extinction that occurred at the Permian-Triassic boundary represents the most extensive loss of species of any known event of the past 550 million years. There have been a wide variety of explanations offered for this extinction. In the present paper, a number of the more popular recent hypotheses are evaluated in terms of predictions that they make, or that they imply, concerning the global carbon cycle. For this purpose, a mass balance model is used that calculates atmospheric CO2 and oceanic delta13C as a function of time. Hypotheses considered include: (i) the release of massive amounts of CO2 from the ocean to the atmosphere resulting in mass poisoning; (ii) the release of large amounts of CO2 from volcanic degassing; (iii) the release of methane stored in methane hydrates; (iv) the decomposition and oxidation of dead organisms to CO2 after sudden mass mortality; and (v) the long-term reorganization of the global carbon cycle. The modeling indicates that measured short-term changes in delta13C at the boundary are best explained by methane release with mass mortality and volcanic degassing contributing in secondary roles. None of the processes result in excessively high levels of atmospheric CO2 if they occurred on time scales of more than about 1,000 years. The idea of poisoning by high levels of atmospheric CO2 depends on the absence of subthermocline calcium carbonate deposition during the latest Permian. The most far-reaching effect was found to be reorganization of the carbon cycle with major sedimentary burial of organic matter shifting from the land to the sea, resulting in less burial overall, decreased atmospheric O2, and higher atmospheric CO2 for the entire Triassic Period. PMID:11917102

  9. 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

  10. Appropriate time scales for nonlinear analyses of deterministic jump systems

    NASA Astrophysics Data System (ADS)

    Suzuki, Tomoya

    2011-06-01

    In the real world, there are many phenomena that are derived from deterministic systems but which fluctuate with nonuniform time intervals. This paper discusses the appropriate time scales that can be applied to such systems to analyze their properties. The financial markets are an example of such systems wherein price movements fluctuate with nonuniform time intervals. However, it is common to apply uniform time scales such as 1-min data and 1-h data to study price movements. This paper examines the validity of such time scales by using surrogate data tests to ascertain whether the deterministic properties of the original system can be identified from uniform sampled data. The results show that uniform time samplings are often inappropriate for nonlinear analyses. However, for other systems such as neural spikes and Internet traffic packets, which produce similar outputs, uniform time samplings are quite effective in extracting the system properties. Nevertheless, uniform samplings often generate overlapping data, which can cause false rejections of surrogate data tests.

  11. Lystrosaurus zone (triassic) fauna from antarctica.

    PubMed

    Kitching, J W; Collinson, J W; Elliot, D H; Colbert, E H

    1972-02-01

    Tetrapod skeletons recently found in the Fremouw Formation in the Shackleton Glacier area, Transantarctic Mountains, include several forms that closely compare to South African species. Faunal similarities that confirm a close connection between Antarctica and Africa during the Triassic Period lend further support to the concept of Gondwanaland and continental drift. PMID:17755654

  12. Middle Triassic source rocks in north Lombardy

    SciTech Connect

    Gnaccolini, M.; Gaetani, M.; Mattavelli, L.; Leoni, C.; Poliani, G.; Riva, A.

    1988-08-01

    Using molecular geochemistry techniques, we established that the Perledo-Verenna and Meride Formations (Middle Triassic, southern Alps) represent the source rocks of the Gaggiano and Villafortuna deep oil fields discovered 40 km northwest of Milan. To find the geological factors which control the areal extent thickness and organic matter distribution relative to these sequences, a sedimentological and geochemical study was undertaken.

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

    USGS Publications Warehouse

    Silberling, Norman 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.

  14. Separation of Time Scales in a Quantum Newton's Cradle.

    PubMed

    van den Berg, R; Wouters, B; Eliëns, S; De Nardis, J; Konik, R M; Caux, J-S

    2016-06-01

    We provide detailed modeling of the Bragg pulse used in quantum Newton's-cradle-like settings or in Bragg spectroscopy experiments for strongly repulsive bosons in one dimension. We reconstruct the postpulse time evolution and study the time-dependent local density profile and momentum distribution by a combination of exact techniques. We further provide a variety of results for finite interaction strengths using a time-dependent Hartree-Fock analysis and bosonization-refermionization techniques. Our results display a clear separation of time scales between rapid and trap-insensitive relaxation immediately after the pulse, followed by slow in-trap periodic behavior. PMID:27314723

  15. Separation of Time Scales in a Quantum Newton's Cradle

    NASA Astrophysics Data System (ADS)

    van den Berg, R.; Wouters, B.; Eliëns, S.; De Nardis, J.; Konik, R. M.; Caux, J.-S.

    2016-06-01

    We provide detailed modeling of the Bragg pulse used in quantum Newton's-cradle-like settings or in Bragg spectroscopy experiments for strongly repulsive bosons in one dimension. We reconstruct the postpulse time evolution and study the time-dependent local density profile and momentum distribution by a combination of exact techniques. We further provide a variety of results for finite interaction strengths using a time-dependent Hartree-Fock analysis and bosonization-refermionization techniques. Our results display a clear separation of time scales between rapid and trap-insensitive relaxation immediately after the pulse, followed by slow in-trap periodic behavior.

  16. 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.

  17. Evidence from ammonoids and conodonts for multiple Early Triassic mass extinctions

    PubMed Central

    Stanley, Steven M.

    2009-01-01

    Ammonoids and conodonts, being characterized by exceptionally high background rates of origination and extinction, were vulnerable to global environmental crises, which characteristically intensified background rates of extinction. Thus, it is not surprising that these taxa suffered conspicuous mass extinctions at the times of three negative Early Triassic global carbon isotopic excursions that resembled those associated with the two preceding Permian mass extinctions. In keeping with their high rates of origination, both the ammonoids and conodonts rediversified dramatically between the Early Triassic crises. Other marine taxa, characterized by much lower intrinsic rates of origination, were held at low levels of diversity by the Early Triassic crises; because global mass extinctions affect all marine life, these taxa must have experienced relatively modest expansions and contractions that have yet to be discovered, because they do not stand out in the fossil record and because the stratigraphic ranges of these taxa, being of little value for temporal correlation, have not been thoroughly studied. PMID:19721005

  18. Time scale algorithm: Definition of ensemble time and possible uses of the Kalman filter

    NASA Technical Reports Server (NTRS)

    Tavella, Patrizia; Thomas, Claudine

    1990-01-01

    The comparative study of two time scale algorithms, devised to satisfy different but related requirements, is presented. They are ALGOS(BIPM), producing the international reference TAI at the Bureau International des Poids et Mesures, and AT1(NIST), generating the real-time time scale AT1 at the National Institute of Standards and Technology. In each case, the time scale is a weighted average of clock readings, but the weight determination and the frequency prediction are different because they are adapted to different purposes. The possibility of using a mathematical tool, such as the Kalman filter, together with the definition of the time scale as a weighted average, is also analyzed. Results obtained by simulation are presented.

  19. 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.

  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. Chron E23r, paleosecular variation, CAMP volcanism and the end-Triassic extinction event (Invited)

    NASA Astrophysics Data System (ADS)

    Kent, D. V.; Wang, H.; Olsen, P. E.

    2009-12-01

    In the early Mesozoic rift basins of eastern North America, CAMP lava flows occur within normal polarity Chron E24n, which according to cycle stratigraphy has a duration of nearly four McLaughlin (405 kyr) cycles, or ~1.6 Ma. In the Newark basin, the level marking the end-Triassic extinction event occurs one Van Houten cycle (20 kyr) before the first CAMP basalt and is preceded within another Van Houten cycle by reverse polarity Chron E23r, one of the shortest (~25 kyr) polarity intervals recognized in the Newark astronomically-tune polarity time scale. This tight chronostratigraphic sequence of events-E23r followed by end-Triassic event and then CAMP lavas within E24n-has been replicated in several sections [1] and a key element (end-Triassic palynofloral turnover preceding the first CAMP lava) is recorded in the Fundy basin of Nova Scotia, where the initial CAMP eruption (North Mountain Basalt) has a rather precise U-Pb (206Pb/238U) zircon date of 201.27± 0.03 Ma [2]. However, two magnetic excursions were found within the Intermediate Basalt (39Ar/40Ar date of 199.9± 0.5 Ma) in the Central High Atlas Mountains of Morocco and correlated to E23r [3, 4], which would imply that the underlying (Lower) basalt unit occurred before and therefore in a possible causal relationship to the end-Triassic extinction event. Paleomagnetic study of the Moroccan basalts also revealed variations in magnetic directions, which were interpreted as a record of secular variation and thus might prove useful for identification of CAMP lavas [4]. We sampled most of the lava flows in the Fundy basin that comprise the ~300 m-thick North Mountain Basalt in outcrop (30 sites) as well as in several industry cores drilled near Margaretsville (GAV-77-3, AV-C-1-4), Freeport (AV-C-1-1), and Westport (AV-C-1-2) in Nova Scotia. We find only two directional groupings for the entire North Mountain Basalt, a finding that basically confirms the results of Carmichael and Palmer [5]. We have yet to find

  2. Supraregional seismites in Triassic - Jurassic boundary strata

    NASA Astrophysics Data System (ADS)

    Lindström, Sofie; Pedersen, Gunver K.; van de Schootbrugge, Bas; Johansson, Leif; Petersen, Henrik I.; Dybkjær, Karen; Weibel, Rikke; Hansen, Katrine H.; Erlström, Mikael; Alwmark, Carl; Nielsen, Lars Henrik; Oschmann, Wolfgang; Tegner, Christian

    2014-05-01

    The end-Triassic mass extinction event (201.564 Ma) was synchronous with the earliest volcanic phase during the emplacement of the Central Atlantic Magmatic Province (CAMP), a large igneous province (LIP) formed during the initial breakup of Pangea. Volcanic degassing of CO2 and other volatile gases, and/or thermogenic methane, from the CAMP is generally regarded as the main cause of the end-Triassic biotic crisis. However, discrepancies in the durations of the ETE (50 Kyrs) and the CAMP volcanism (600 Kyrs) as well as temporal offsets between carbon cycle perturbations and biotic turnovers suggest a more complex scenario that require further studies of the temporal succession of events in Triassic-Jurassic (TJ) boundary strata. Here, we present and examine multiple episodes of soft-sediment deformation (seismite) within uppermost Rhaetian marine and terrestrial strata of Denmark, Sweden and Germany. These seismites are stratigraphically constrained by palynology and C-isotopes to the latest Rhaetian, and are synchronous to the single seismite layer from the UK, which similarly predates the T/J boundary, and has been explained by an extraterrestrial bolide impact. Instead, we argue that the multiple episodes of soft-sediment deformation, interbedded by undisturbed strata, were formed from repeated intense earthquake activity restricted to an interval within the latest Rhaetian bracketed by two negative excursions in δ13C and also containing palynological evidence for deforestation and fern proliferation. The fact that these biotic changes coincide with repeated seismic activity has implications for the end-Triassic extinction and the CAMP scenario. We discuss the temporal position of the seismites in regards to other end-Triassic events, and argue that their supraregional distribution in pre-TJ-boundary strata of NW Europe may be linked to intensified earthquake activity during CAMP emplacement, rather than an extraterrestrial impact.

  3. 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 (ω) of in-stream temperature fluctuation scales with the effective thermal diffusivity (κe) and the vertical separation distance between the pairs of temperature (ɛ) data as ω ≈ κe/(2ɛ2), 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

  4. Characterization of a binary karst aquifer using process time scales

    NASA Astrophysics Data System (ADS)

    Birk, Steffen; Wagner, Thomas

    2013-04-01

    Within "a theoretical framework for the interpretation of karst spring signals" (Covington, EGU2012-853-1) process length scales that characterize the travel distances required for damping pulses of physicochemical parameters of spring waters such as electrical conductivity and temperature were derived (Covington et al., J. Geophys. Res., 2012). These length scales can be converted to corresponding process time scales characterizing the travel times needed for damping the pulses. This is particularly convenient if the travel distance is unknown. In this case the time lag between the increase of spring discharge and subsequent physicochemical responses at the spring may provide an estimate of the travel time. In binary karst aquifers with localized recharge from a sinking stream, the recharge pulse can be directly observed and thus travel times are readily obtained from the time delay of the physicochemical spring responses. If the spring response is strongly damped travel times can be inferred from artificial tracer testing. In this work, time scales for carbonate dissolution and heat transport were used for characterizing the binary Lurbach-Tanneben karst aquifer (Austria). This aquifer receives allogenic recharge from the sinking stream Lurbach and is drained by two springs, namely the Hammerbach and the Schmelzbach. The two springs show different thermal responses to two recharge events in December 2008: Whereas the temperature of the Schmelzbach responds within one day after the flood pulse in the Lurbach, the temperature signal is strongly damped at the Hammerbach. The evaluation based on the thermal time scale thus suggests that the Schmelzbach spring is fed by conduits with hydraulic diameters at least in the order of decimetres. In contrast, the damping of the thermal responses at the Hammerbach may be due to lower hydraulic diameters and/or longer residence times. Interestingly, the Hammerbach did show thermal responses in the time before a flood event in

  5. The Late Permian - Early Triassic Evolution of the Western Barents Sea

    NASA Astrophysics Data System (ADS)

    Planke, S.; Svensen, H.; Faleide, J.; Myklebust, R.

    2013-12-01

    The Permian-Triassic boundary was temporarily associated with formation of the Siberian Traps Large Igneous Province. Major Late Permian and Early Triassic subsidence is documented by seismic reflection data in the East Barents Basin. Further west, basin subsidence and an abrupt change from carbonate and evaporite deposition to clastic sedimentation is recorded by industry seismic and well data in the south and onshore Svalbard in the north. The Permian-Triassic boundary is commonly not preserved either due to non-deposition or erosion, but could be locally preserved in depocenters. A major northwestward prograding clastic delta sourced from the Uralian hinterland reached the Norwegian (western) part of the Barents Sea in the earliest Triassic (Induan). We suggest that the large-scale changes in paleoenviroment, vertical motions, and sedimentary processes in the Barents Sea region were strongly influenced by large-scale changes in mantle dynamics and paleoclimate caused by the Siberian Traps igneous event. By analogy with other Large Igneous Provinces, such as the North Atlantic Volcanic Province, regional uplift and subsidence associated with a rising mantle plume may precede the arrival of the plume at the base of the lithosphere with 10's of millions of years. In contrast, the paleoenvironmental changes and the associated extinction were mainly caused by rapid intrusion of magma into sedimentary basins and voluminous igneous eruptions.

  6. Tectonic evolution of the Songpan Garzê and adjacent areas (NE Tibet) from Triassic to Present : a synthesis.

    NASA Astrophysics Data System (ADS)

    Roger, F.; Jolivet, M.; Malavieille, J.

    2009-04-01

    The 12th May 2008 Wenchuan earthquake in the Longmen Shan occurred on a large thrust fault largely inherited from an Indosinian structure itself probably controlled by an older structural heritage of the South China block continental margin. Within the whole northeast Tibet region, such a structural inheritance has had a major impact on the Tertiary deformation. It appears of primary importance to assess the pre-Tertiary tectonic evolution of the main blocks involved to understand the actual deformation in the eastern edge of Tibet. Over the past decades, the Proterozoic to Cenozoic tectonic, metamorphic and geochronologic history of the Longmen Shan and Songpan Garzê area have been largely studied. We present a synthesis of the tectonic evolution of the Songpan Garzê fold and thrust belt from Triassic to present. The Songpan-Garzê belt was formed during closure of a wide oceanic basin filled with a thick (5 to 15 km) sequence of Triassic flyschoid sediments [10]. Closure of the basin due to Triassic subduction involved strong shortening, intense folding and faulting of the Triassic series. A large-scale décollement, that presently outcrops along the eastern boundary of the belt (Danba area), allowed the growth of a wide and thick accretionary wedge [9]. It develops in the Paleozoic and Triassic series and separates the accretionary prism from an autochthonous crystalline basement [5, 12, 6] which shares many similarities with the basement of the Yangtze Craton (0.7-0.9 Ga). To the north and northwest, below the thickened Triassic series of the belt, the composition (oceanic or continental) of the basement remains unknown. During the Indosinian orogeny the emplacement of orogenic granites (220 - 150 Ma) was associated to crustal thickening [12, 13, 17, 15]. The isotopic composition of granitoids shows that their magma source were predominantly derived from melting of the proterozoic basement with varying degrees of sedimentary material and negligible mantle

  7. The Available Time Scale: Measuring Foster Parents' Available Time to Foster

    ERIC Educational Resources Information Center

    Cherry, Donna J.; Orme, John G.; Rhodes, Kathryn W.

    2009-01-01

    This article presents a new measure of available time specific to fostering, the Available Time Scale (ATS). It was tested with a national sample of 304 foster mothers and is designed to measure the amount of time foster parents are able to devote to fostering activities. The ATS has excellent reliability, and good support exists for its validity.…

  8. 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

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

    NASA Astrophysics Data System (ADS)

    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

    2014-11-01

    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.

  10. 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

  11. 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.

  12. Energy and time determine scaling in biological and computer designs.

    PubMed

    Moses, Melanie; Bezerra, George; Edwards, Benjamin; Brown, James; Forrest, Stephanie

    2016-08-19

    Metabolic rate in animals and power consumption in computers are analogous quantities that scale similarly with size. We analyse vascular systems of mammals and on-chip networks of microprocessors, where natural selection and human engineering, respectively, have produced systems that minimize both energy dissipation and delivery times. Using a simple network model that simultaneously minimizes energy and time, our analysis explains empirically observed trends in the scaling of metabolic rate in mammals and power consumption and performance in microprocessors across several orders of magnitude in size. Just as the evolutionary transitions from unicellular to multicellular animals in biology are associated with shifts in metabolic scaling, our model suggests that the scaling of power and performance will change as computer designs transition to decentralized multi-core and distributed cyber-physical systems. More generally, a single energy-time minimization principle may govern the design of many complex systems that process energy, materials and information.This article is part of the themed issue 'The major synthetic evolutionary transitions'. PMID:27431524

  13. Time scales and heterogeneous structure in geodynamic earth models

    PubMed

    Bunge; Richards; Lithgow-Bertelloni; Baumgardner; Grand; Romanowicz

    1998-04-01

    Computer models of mantle convection constrained by the history of Cenozoic and Mesozoic plate motions explain some deep-mantle structural heterogeneity imaged by seismic tomography, especially those related to subduction. They also reveal a 150-million-year time scale for generating thermal heterogeneity in the mantle, comparable to the record of plate motion reconstructions, so that the problem of unknown initial conditions can be overcome. The pattern of lowermost mantle structure at the core-mantle boundary is controlled by subduction history, although seismic tomography reveals intense large-scale hot (low-velocity) upwelling features not explicitly predicted by the models. PMID:9525864

  14. Wavelet analysis and scaling properties of time series

    NASA Astrophysics Data System (ADS)

    Manimaran, P.; Panigrahi, Prasanta K.; Parikh, Jitendra C.

    2005-10-01

    We propose a wavelet based method for the characterization of the scaling behavior of nonstationary time series. It makes use of the built-in ability of the wavelets for capturing the trends in a data set, in variable window sizes. Discrete wavelets from the Daubechies family are used to illustrate the efficacy of this procedure. After studying binomial multifractal time series with the present and earlier approaches of detrending for comparison, we analyze the time series of averaged spin density in the 2D Ising model at the critical temperature, along with several experimental data sets possessing multifractal behavior.

  15. Wavelet analysis and scaling properties of time series.

    PubMed

    Manimaran, P; Panigrahi, Prasanta K; Parikh, Jitendra C

    2005-10-01

    We propose a wavelet based method for the characterization of the scaling behavior of nonstationary time series. It makes use of the built-in ability of the wavelets for capturing the trends in a data set, in variable window sizes. Discrete wavelets from the Daubechies family are used to illustrate the efficacy of this procedure. After studying binomial multifractal time series with the present and earlier approaches of detrending for comparison, we analyze the time series of averaged spin density in the 2D Ising model at the critical temperature, along with several experimental data sets possessing multifractal behavior. PMID:16383481

  16. Brownian motion at fast time scales and thermal noise imaging

    NASA Astrophysics Data System (ADS)

    Huang, Rongxin

    This dissertation presents experimental studies on Brownian motion at fast time scales, as well as our recent developments in Thermal Noise Imaging which uses thermal motions of microscopic particles for spatial imaging. As thermal motions become increasingly important in the studies of soft condensed matters, the study of Brownian motion is not only of fundamental scientific interest but also has practical applications. Optical tweezers with a fast position-sensitive detector provide high spatial and temporal resolution to study Brownian motion at fast time scales. A novel high bandwidth detector was developed with a temporal resolution of 30 ns and a spatial resolution of 1 A. With this high bandwidth detector, Brownian motion of a single particle confined in an optical trap was observed at the time scale of the ballistic regime. The hydrodynamic memory effect was fully studied with polystyrene particles of different sizes. We found that the mean square displacements of different sized polystyrene particles collapse into one master curve which is determined by the characteristic time scale of the fluid inertia effect. The particle's inertia effect was shown for particles of the same size but different densities. For the first time the velocity autocorrelation function for a single particle was shown. We found excellent agreement between our experiments and the hydrodynamic theories that take into account the fluid inertia effect. Brownian motion of a colloidal particle can be used to probe three-dimensional nano structures. This so-called thermal noise imaging (TNI) has been very successful in imaging polymer networks with a resolution of 10 nm. However, TNI is not efficient at micrometer scale scanning since a great portion of image acquisition time is wasted on large vacant volume within polymer networks. Therefore, we invented a method to improve the efficiency of large scale scanning by combining traditional point-to-point scanning to explore large vacant

  17. Palaeoenvironments and palaeotectonics of the arid to hyperarid intracontinental latest Permian- late Triassic Solway basin (U.K.)

    NASA Astrophysics Data System (ADS)

    Brookfield, Michael E.

    2008-10-01

    The late Permian to late Triassic sediments of the Solway Basin consist of an originally flat-lying, laterally persistent and consistent succession of mature, dominantly fine-grained red clastics laid down in part of a very large intracontinental basin. The complete absence of body or trace fossils or palaeosols indicates a very arid (hyperarid) depositional environment for most of the sediments. At the base of the succession, thin regolith breccias and sandstones rest unconformably on basement and early Permian rift clastics. Overlying gypsiferous red silty mudstones, very fine sandstones and thick gypsum were deposited in either a playa lake or in a hypersaline estuary, and their margins. These pass upwards into thick-bedded, multi-storied, fine- to very fine-grained red quartzo-felspathic and sublithic arenites in which even medium sand is rare despite channels with clay pebbles up to 30 cm in diameter. Above, thick trough cross-bedded and parallel laminated fine-grained aeolian sandstones (deposited in extensive barchanoid dune complexes) pass up into very thick, multicoloured mudstones, and gypsum deposited in marginal marine or lacustrine sabkha environments. The latter pass up into marine Lower Jurassic shales and limestones. Thirteen non-marine clastic lithofacies are arranged into five main lithofacies associations whose facies architecture is reconstructed where possible by analysis of large exposures. The five associations can be compared with the desert pavement, arid ephemeral stream, sabkha, saline lake and aeolian sand dune environments of the arid to hyperarid areas of existing intracontinental basins such as Lake Eyre and Lake Chad. The accommodation space in such basins is controlled by gradual tectonic subsidence moderated by large fluctuations in shallow lake extent (caused by climatic change and local variation) and this promotes a large-scale layer-cake stratigraphy as exemplified in the Solway basin. Here, the dominant fine-grained mature

  18. 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

  19. Surface charge measurements in barrier discharges on different time scales

    NASA Astrophysics Data System (ADS)

    Wild, Robert; Volkhausen, Christian; Benduhn, Johannes; Stollenwerk, Lars

    2015-09-01

    The deposition of surface charge in barrier discharges is a process that influences the ongoing discharge significantly. This contribution presents the measurement of absolute surface charge densities and their dynamics in a laterally extended setup. An electro-optic BSO crystal is used as dielectric. The absolute charge density on its surface is deduced from the change of polarisation of light passing the crystal. Using different temporal resolutions, the behavior of charge is investigated on three different time scales. The highest temporal resolution of the technique is in the order of hundreds of nanoseconds. Therefore it is possible for the first time to observe the charge deposition process during an active discharge. On the time scale of the applied voltage period (several microseconds), the conservation mechanisms of a lateral discharge pattern is investigated. For this, the influence of surface charge and metastable species in the volume is estimated. Further, the behavior of the surface charge spots on a variation of the external voltage and gas pressure is studied. Measurements on a time scale in the magnitude of seconds reveal charge decay and transport phenomena. This work was funded by the Deutsche Forschungsgemeinschaft.

  20. Reconstructions of solar irradiance on centennial time scales

    NASA Astrophysics Data System (ADS)

    Krivova, Natalie; Solanki, Sami K.; Dasi Espuig, Maria; Kok Leng, Yeo

    Solar irradiance is the main external source of energy to Earth's climate system. The record of direct measurements covering less than 40 years is too short to study solar influence on Earth's climate, which calls for reconstructions of solar irradiance into the past with the help of appropriate models. An obvious requirement to a competitive model is its ability to reproduce observed irradiance changes, and a successful example of such a model is presented by the SATIRE family of models. As most state-of-the-art models, SATIRE assumes that irradiance changes on time scales longer than approximately a day are caused by the evolving distribution of dark and bright magnetic features on the solar surface. The surface coverage by such features as a function of time is derived from solar observations. The choice of these depends on the time scale in question. Most accurate is the version of the model that employs full-disc spatially-resolved solar magnetograms and reproduces over 90% of the measured irradiance variation, including the overall decreasing trend in the total solar irradiance over the last four cycles. Since such magnetograms are only available for about four decades, reconstructions on time scales of centuries have to rely on disc-integrated proxies of solar magnetic activity, such as sunspot areas and numbers. Employing a surface flux transport model and sunspot observations as input, we have being able to produce synthetic magnetograms since 1700. This improves the temporal resolution of the irradiance reconstructions on centennial time scales. The most critical aspect of such reconstructions remains the uncertainty in the magnitude of the secular change.

  1. The Triassic of the Kocaeli Peninsula (NW Turkey) with emphasis on Anisian conodonts

    NASA Astrophysics Data System (ADS)

    Murat Kilic, Ali

    2016-04-01

    In the present structural concept, the Kocaeli Peninsula, as a part of the Istanbul Zone, was in Triassic times part of an Eurasian fragment on the northern edge of the northernmost Tethys branch. The Triassic sequence, exposed in the Kocaeli Peninsula (NW Turkey), represents well dated transgressive and regressive marine deposits. This "Kocaeli Triassic", being regarded as an important Triassic sequence has attracted the attention of a large number of scientists. The Kocaeli Triassic encompasses six formations: The red coloured Scythian Kapaklı Formation is barren and shows regressive features, resembling the underlying Permian facies; The Erikli Formation is the first marine deposition of Scythian age. The Late Scythian Demirciler Formation consists of micritic and dolomitic limestone. The unit shows bioturbation in the clayey limestone-limestone sequence. Covering a karstic surface, the Anisian Ballıkaya Formation consists of dolomite, dolomitic limestone and limestone, follow by the Tepeköy Formation that shows 4 different lithologies. At base, Anisian grey nodular and red nodular limestones equals the nodular limestones of the Kazmalı Formation laterally; The Late Anisian-Ladinian Ammonitico Rosso facies. The upper part consists of Carnian shale with Halobia and grey-green marls. Restricted to the Çerkeşli region, the Çerkeşli Formation consists of a pebbly limestones, as a lateral equivalent of the Tepeköy Formation. The Anisian platform conodonts include new taxa that are described. We also focus on several new ramiforms, adding to the multi-elemental and taxonomic diversities. The revised Anisian conodont biostratigraphy is presented. Key Words: Triassic, Anisian, Conodont, Kocaeli

  2. 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.

  3. Sublinear scaling for time-dependent stochastic density functional theory

    SciTech Connect

    Gao, Yi; Neuhauser, Daniel; Baer, Roi; Rabani, Eran

    2015-01-21

    A stochastic approach to time-dependent density functional theory is developed for computing the absorption cross section and the random phase approximation (RPA) correlation energy. The core idea of the approach involves time-propagation of a small set of stochastic orbitals which are first projected on the occupied space and then propagated in time according to the time-dependent Kohn-Sham equations. The evolving electron density is exactly represented when the number of random orbitals is infinite, but even a small number (≈16) of such orbitals is enough to obtain meaningful results for absorption spectrum and the RPA correlation energy per electron. We implement the approach for silicon nanocrystals using real-space grids and find that the overall scaling of the algorithm is sublinear with computational time and memory.

  4. 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.

  5. 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.

  6. Space and time scales in human-landscape systems.

    PubMed

    Kondolf, G Mathias; Podolak, Kristen

    2014-01-01

    Exploring spatial and temporal scales provides a way to understand human alteration of landscape processes and human responses to these processes. We address three topics relevant to human-landscape systems: (1) scales of human impacts on geomorphic processes, (2) spatial and temporal scales in river restoration, and (3) time scales of natural disasters and behavioral and institutional responses. Studies showing dramatic recent change in sediment yields from uplands to the ocean via rivers illustrate the increasingly vast spatial extent and quick rate of human landscape change in the last two millennia, but especially in the second half of the twentieth century. Recent river restoration efforts are typically small in spatial and temporal scale compared to the historical human changes to ecosystem processes, but the cumulative effectiveness of multiple small restoration projects in achieving large ecosystem goals has yet to be demonstrated. The mismatch between infrequent natural disasters and individual risk perception, media coverage, and institutional response to natural disasters results in un-preparedness and unsustainable land use and building practices. PMID:23716006

  7. Tailored real-time scaling of heteronuclear couplings

    NASA Astrophysics Data System (ADS)

    Schilling, Franz; Glaser, Steffen J.

    2012-10-01

    Heteronuclear couplings are a valuable source of molecular information, which is measured from the multiplet splittings of an NMR spectrum. Radiofrequency irradiation on one coupled nuclear spin allows to modify the effective coupling constant, scaling down the multiplet splittings in the spectrum observed at the resonance frequency of the other nuclear spin. Such decoupling sequences are often used to collapse a multiplet into a singlet and can therefore simplify NMR spectra significantly. Continuous-wave (cw) decoupling has an intrinsic non-linear offset dependence of the scaling of the effective J-coupling constant. Using optimal control pulse optimization, we show that virtually arbitrary off-resonance scaling of the J-coupling constant can be achieved. The new class of tailored decoupling pulses is named SHOT (Scaling of Heteronuclear couplings by Optimal Tracking). Complementing cw irradiation, SHOT pulses offer an alternative approach of encoding chemical shift information indirectly through off-resonance decoupling, which however makes it possible for the first time to achieve linear J scaling as a function of offset frequency. For a simple mixture of eight aromatic compounds, it is demonstrated experimentally that a 1D-SHOT {1H}-13C experiment yields comparable information to a 2D-HSQC and can give full assignment of all coupled spins.

  8. Does the Permo-Triassic Geomagnetic Dipole Low Exist?

    NASA Astrophysics Data System (ADS)

    Blanco, D.; Kravchinsky, V. A.; Valet, J. M.

    2010-12-01

    The Siberian trap basalts erupted during a short period of ~1 Myr at the Permo-Triassic boundary. It provides a unique opportunity to study absolute paleointensity during this one of the best-dated periods of Paleozoic era. Previous studies suggest relatively low paleointensity values (Heunemann et al. 2004), result that leads the authors to propose that the Mesozoic Dipole Low could be extended at least to the Permo-Triassic boundary. In this contribution we present new paleointensity results for sills and dykes from the eastern (areas of the kimberlite pipes Sytikanskaya, Yubileinaya and Aikhal) and north-western (intrusions near Norilsk city) parts of the Siberian platform. A total of 341 samples were subject to a modified Thellier-Thellier technique. In order to assure the reliability of the paleointensity estimates partial thermoremanent magnetization checks and multidomain tail check were applied. North-western (Norilsk) samples did not meet reliability criteria and have been rejected from the paleointensity analysis although paleomagnetic analysis demonstrated matching to the expected Permo-Triassic direction of the Siberian traps. Our paleointensity estimates from the eastern trap occurrences show a virtual dipolar moment (VDM) close to the present geomagnetic field value, 5.71±0.92×1022Am2, 5.89±0.37×1022Am2 and 6.21±0.78×1022Am2 for the three study areas, respectively. Our values are about two times higher than reported in Heunemann et al. (2004). There could be a variety of reasons for the discrepancy between our results and previous studies: (1) Magnetostratigraphy studies on the Siberian trap basalts (Gurevitch et al. 2004) have shown that several reversal processes occurred during the time of their formation. As shown by Valet et al. (2005), a period of time is required for the geomagnetic field to recover after a reversal occurrence. During such period it is still possible to have a stable normal or reverse direction and low paleointensity

  9. Statistical Analysis of Sensor Network Time Series at Multiple Time Scales

    NASA Astrophysics Data System (ADS)

    Granat, R. A.; Donnellan, A.

    2013-12-01

    Modern sensor networks often collect data at multiple time scales in order to observe physical phenomena that occur at different scales. Whether collected by heterogeneous or homogenous sensor networks, measurements at different time scales are usually subject to different dynamics, noise characteristics, and error sources. We explore the impact of these effects on the results of statistical time series analysis methods applied to multi-scale time series data. As a case study, we analyze results from GPS time series position data collected in Japan and the Western United States, which produce raw observations at 1Hz and orbit corrected observations at time resolutions of 5 minutes, 30 minutes, and 24 hours. We utilize the GPS analysis package (GAP) software to perform three types of statistical analysis on these observations: hidden Markov modeling, probabilistic principle components analysis, and covariance distance analysis. We compare the results of these methods at the different time scales and discuss the impact on science understanding of earthquake fault systems generally and recent large seismic events specifically, including the Tohoku-Oki earthquake in Japan and El Mayor-Cucupah earthquake in Mexico.

  10. 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.

  11. Selective visual scaling of time-scale processes facilitates broadband learning of isometric force frequency tracking.

    PubMed

    King, Adam C; Newell, Karl M

    2015-10-01

    The experiment investigated the effect of selectively augmenting faster time scales of visual feedback information on the learning and transfer of continuous isometric force tracking tasks to test the generality of the self-organization of 1/f properties of force output. Three experimental groups tracked an irregular target pattern either under a standard fixed gain condition or with selectively enhancement in the visual feedback display of intermediate (4-8 Hz) or high (8-12 Hz) frequency components of the force output. All groups reduced tracking error over practice, with the error lowest in the intermediate scaling condition followed by the high scaling and fixed gain conditions, respectively. Selective visual scaling induced persistent changes across the frequency spectrum, with the strongest effect in the intermediate scaling condition and positive transfer to novel feedback displays. The findings reveal an interdependence of the timescales in the learning and transfer of isometric force output frequency structures consistent with 1/f process models of the time scales of motor output variability. PMID:26041272

  12. The length and time scales of water's glass transitions

    NASA Astrophysics Data System (ADS)

    Limmer, David T.

    2014-06-01

    Using a general model for the equilibrium dynamics of supercooled liquids, I compute from molecular properties the emergent length and time scales that govern the nonequilibrium relaxation behavior of amorphous ice prepared by rapid cooling. Upon cooling, the liquid water falls out of equilibrium whereby the temperature dependence of its relaxation time is predicted to change from super-Arrhenius to Arrhenius. A consequence of this crossover is that the location of the apparent glass transition temperature depends logarithmically on cooling rate. Accompanying vitrification is the emergence of a dynamical length-scale, the size of which depends on the cooling rate and varies between angstroms and tens of nanometers. While this protocol dependence clarifies a number of previous experimental observations for amorphous ice, the arguments are general and can be extended to other glass forming liquids.

  13. Entropy Production of Nanosystems with Time Scale Separation

    NASA Astrophysics Data System (ADS)

    Wang, Shou-Wen; Kawaguchi, Kyogo; Sasa, Shin-ichi; Tang, Lei-Han

    2016-08-01

    Energy flows in biomolecular motors and machines are vital to their function. Yet experimental observations are often limited to a small subset of variables that participate in energy transport and dissipation. Here we show, through a solvable Langevin model, that the seemingly hidden entropy production is measurable through the violation spectrum of the fluctuation-response relation of a slow observable. For general Markov systems with time scale separation, we prove that the violation spectrum exhibits a characteristic plateau in the intermediate frequency region. Despite its vanishing height, the plateau can account for energy dissipation over a broad time scale. Our findings suggest a general possibility to probe hidden entropy production in nanosystems without direct observation of fast variables.

  14. Entropy Production of Nanosystems with Time Scale Separation.

    PubMed

    Wang, Shou-Wen; Kawaguchi, Kyogo; Sasa, Shin-Ichi; Tang, Lei-Han

    2016-08-12

    Energy flows in biomolecular motors and machines are vital to their function. Yet experimental observations are often limited to a small subset of variables that participate in energy transport and dissipation. Here we show, through a solvable Langevin model, that the seemingly hidden entropy production is measurable through the violation spectrum of the fluctuation-response relation of a slow observable. For general Markov systems with time scale separation, we prove that the violation spectrum exhibits a characteristic plateau in the intermediate frequency region. Despite its vanishing height, the plateau can account for energy dissipation over a broad time scale. Our findings suggest a general possibility to probe hidden entropy production in nanosystems without direct observation of fast variables. PMID:27563943

  15. Long-term variation time scales in OJ 287

    NASA Astrophysics Data System (ADS)

    Fan, Jun-Hui; Liu, Yi; Qian, Bo-Chun; Tao, Jun; Shen, Zhi-Qiang; Zhang, Jiang-Shui; Huang, Yong; Wang, Jin

    2010-11-01

    The light curve data from 1894 to 2008 are compiled for the BL Lacertae object OJ 287 from the available literature. Periodicity analysis methods (the Discrete Correlation Function-DCF, the Jurkevich method, the power spectral (Fourier) analysis, and the CLEANest method) are performed to search for possible periodicites in the light curve of OJ 287. Significance levels are given for the possible periods. The analysis results confirm the existence of the 12.2±0.6 yr time scale and show a hint of a ~53 yr time scale. The 12.2±0.6 yr period is used as the orbital period to investigate the supermassive binary black hole system parameters.

  16. Sub-diffusive scaling with power-law trapping times

    NASA Astrophysics Data System (ADS)

    Luo, Liang; Tang, Lei-Han

    2014-07-01

    Thermally driven diffusive motion of a particle underlies many physical and biological processes. In the presence of traps and obstacles, the spread of the particle is substantially impeded, leading to subdiffusive scaling at long times. The statistical mechanical treatment of diffusion in a disordered environment is often quite involved. In this short review, we present a simple and unified view of the many quantitative results on anomalous diffusion in the literature, including the scaling of the diffusion front and the mean first-passage time. Various analytic calculations and physical arguments are examined to highlight the role of dimensionality, energy landscape, and rare events in affecting the particle trajectory statistics. The general understanding that emerges will aid the interpretation of relevant experimental and simulation results.

  17. Adaptive Haar transforms with arbitrary time and scale splitting

    NASA Astrophysics Data System (ADS)

    Egiazarian, Karen O.; Astola, Jaakko T.

    2001-05-01

    The Haar transform is generalized to the case of an arbitrary time and scale splitting. To any binary tree we associate an orthogonal system of Haar-type functions - tree-structured Haar (TSH) functions. Unified fast algorithm for computation of the introduced tree-structured Haar transforms is presented. It requires 2(N - 1) additions and 3N - 2 multiplications, where N is transform order or, equivalently, the number of leaves of the binary tree.

  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. 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.

  20. Time scale interactions and the coevolution of humans and water

    NASA Astrophysics Data System (ADS)

    Sivapalan, Murugesu; Blöschl, Günter

    2015-09-01

    We present a coevolutionary view of hydrologic systems, revolving around feedbacks between environmental and social processes operating across different time scales. This brings to the fore an emphasis on emergent phenomena in changing water systems, such as the levee effect, adaptation to change, system lock-in, and system collapse due to resource depletion. Changing human values play a key role in the emergence of these phenomena and should therefore be considered as internal to the system. Guidance is provided for the framing and modeling of these phenomena to test alternative hypotheses about how they arose. A plurality of coevolutionary models, from stylized to comprehensive system-of-system models, may assist strategic water management for long time scales through facilitating stakeholder participation, exploring the possibility space of alternative futures, and helping to synthesize the observed dynamics in a wide range of case studies. Future research opportunities lie in exploring emergent phenomena arising from time scale interactions through historical, comparative, and process studies of human-water feedbacks.

  1. Backpropagation and ordered derivatives in the time scales calculus.

    PubMed

    Seiffertt, John; Wunsch, Donald C

    2010-08-01

    Backpropagation is the most widely used neural network learning technique. It is based on the mathematical notion of an ordered derivative. In this paper, we present a formulation of ordered derivatives and the backpropagation training algorithm using the important emerging area of mathematics known as the time scales calculus. This calculus, with its potential for application to a wide variety of inter-disciplinary problems, is becoming a key area of mathematics. It is capable of unifying continuous and discrete analysis within one coherent theoretical framework. Using this calculus, we present here a generalization of backpropagation which is appropriate for cases beyond the specifically continuous or discrete. We develop a new multivariate chain rule of this calculus, define ordered derivatives on time scales, prove a key theorem about them, and derive the backpropagation weight update equations for a feedforward multilayer neural network architecture. By drawing together the time scales calculus and the area of neural network learning, we present the first connection of two major fields of research. PMID:20615808

  2. Scale dependence of the directional relationships between coupled time series

    NASA Astrophysics Data System (ADS)

    Shirazi, Amir Hossein; Aghamohammadi, Cina; Anvari, Mehrnaz; Bahraminasab, Alireza; Rahimi Tabar, M. Reza; Peinke, Joachim; Sahimi, Muhammad; Marsili, Matteo

    2013-02-01

    Using the cross-correlation of the wavelet transformation, we propose a general method of studying the scale dependence of the direction of coupling for coupled time series. The method is first demonstrated by applying it to coupled van der Pol forced oscillators and coupled nonlinear stochastic equations. We then apply the method to the analysis of the log-return time series of the stock values of the IBM and General Electric (GE) companies. Our analysis indicates that, on average, IBM stocks react earlier to possible common sector price movements than those of GE.

  3. Scale and time dependence of serial correlations in word-length time series of written texts

    NASA Astrophysics Data System (ADS)

    Rodriguez, E.; Aguilar-Cornejo, M.; Femat, R.; Alvarez-Ramirez, J.

    2014-11-01

    This work considered the quantitative analysis of large written texts. To this end, the text was converted into a time series by taking the sequence of word lengths. The detrended fluctuation analysis (DFA) was used for characterizing long-range serial correlations of the time series. To this end, the DFA was implemented within a rolling window framework for estimating the variations of correlations, quantified in terms of the scaling exponent, strength along the text. Also, a filtering derivative was used to compute the dependence of the scaling exponent relative to the scale. The analysis was applied to three famous English-written literary narrations; namely, Alice in Wonderland (by Lewis Carrol), Dracula (by Bram Stoker) and Sense and Sensibility (by Jane Austen). The results showed that high correlations appear for scales of about 50-200 words, suggesting that at these scales the text contains the stronger coherence. The scaling exponent was not constant along the text, showing important variations with apparent cyclical behavior. An interesting coincidence between the scaling exponent variations and changes in narrative units (e.g., chapters) was found. This suggests that the scaling exponent obtained from the DFA is able to detect changes in narration structure as expressed by the usage of words of different lengths.

  4. Events during Early Triassic recovery from the end-Permian extinction

    NASA Astrophysics Data System (ADS)

    Tong, Jinnan; Zhang, Suxin; Zuo, Jingxun; Xiong, Xinqi

    2007-01-01

    of the biota therefore took a relatively long time. The environmental events at the Permian-Triassic boundary might not be significantly different from those at other Phanerozoic transitions, but they consisted of a series of events that occurred at intervals during the transitional period.

  5. Time scaling with efficient time-propagation techniques for atoms and molecules in pulsed radiation fields

    SciTech Connect

    Hamido, Aliou; Frapiccini, Ana Laura; Piraux, Bernard; Eiglsperger, Johannes; Madronero, Javier; Mota-Furtado, Francisca; O'Mahony, Patrick

    2011-07-15

    We present an ab initio approach to solving the time-dependent Schroedinger equation to treat electron- and photon-impact multiple ionization of atoms or molecules. It combines the already known time-scaled coordinate method with a high-order time propagator based on a predictor-corrector scheme. In order to exploit in an optimal way the main advantage of the time-scaled coordinate method, namely, that the scaled wave packet stays confined and evolves smoothly toward a stationary state, of which the squared modulus is directly proportional to the electron energy spectra in each ionization channel, we show that the scaled bound states should be subtracted from the total scaled wave packet. In addition, our detailed investigations suggest that multiresolution techniques like, for instance, wavelets are the most appropriate ones to represent the scaled wave packet spatially. The approach is illustrated in the case of the interaction of a one-dimensional model atom as well as atomic hydrogen with a strong oscillating field.

  6. 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

  7. 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.

  8. Triassic oils and related hydrocarbon kitchens in the Adriatic basin

    SciTech Connect

    Novelli, L.; Demaison, G. )

    1988-08-01

    Without exception, the oils from both the Abruzzi basin and Albanian foredeep are of lower Liassic to Upper Triassic origin. This is demonstrated by biological marker-based correlations between the oils and stratigraphically controlled, carbonate-rich source rocks. The biomarker studies also provided proof to conclude that many of the oils possess low API gravities and high sulfur contents because they are immature rather than biodegraded. Following the geochemical investigations, a computer-aided, basinwise maturation simulation of the hydrocarbon kitchens was carried out, with backstripping in geologic time. The simulations, performed with the Tissot-Espitalie kinetic model, used basin-specific kerogen activation energies obtained by the optimum method. These simulated values were calibrated with observed values in deep wells. Two characteristics diverge from normal petroleum basin situations (e.g., the North Sea basin): sulfur-rich kerogens in the source rocks, featuring relatively low activation energy distributions, and low geothermal gradients in the subsurface. The geographic outlines of simulated Triassic-lower Liassic hydrocarbon kitchens closely coincide with the zones of petroleum occurrence and production in the Adriatic basin. Furthermore, API gravities of the oils are broadly predicted by the mathematical simulations. This methodology has once again shown its ability to rationally high-grade the petroleum-rich sectors of sedimentary basin while identifying those areas where chances of success are extremely low regardless of the presence of structures.

  9. Stratigraphy and environmental significance of continental Triassic rock of Texas

    SciTech Connect

    Gawloski, T.

    1983-03-01

    The continental Triassic rocks of Texas are represented by four distinct but similar rock groups that exist both in outcrop and in the subsurface and include the Eagle Mills Formation (south-central and northeast Texas), Sycamore Formation (central Texas), Dockum Group (west Texas), and Bissett Formation (southwest Texas). They are clearly terrigenous in nature derived principally from older Paleozoic sedimentary rocks. The rock groups are composed in part or entirely of mudstone, siltstone, medium to coarse-grained sandstone, and pebble to boulder conglomerate (intrabasinal and extrabasinal). The sediments were deposited in alluvial fans, braided and meandering streams, lobate deltas, fan deltas, and lakes. The coarse sandstone and conglomerate are the products of high-energy, short-duration depositional events. Sedimentation was greatly affected by alternating climatic conditions that produced changes in base level, water depth, and lake area as well as the type of streams that flowed into the depositional basins. The character of the rock groups strongly suggests semi-arid to arid deposition typical of the low latitude desert regions of today. Thus, the rocks comprising the Eagle Mills, Sycamore, Dockum, and Bissett Formations appear to be products of continental clastic deposition during a major semi-arid to arid climatic episode, such as that of late Triassic time.

  10. 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.

  11. Time scaling of tree rings cell production in Siberia

    NASA Astrophysics Data System (ADS)

    Popkova, Margarita; Babushkina, Elena; Tychkov, Ivan; Shishov, Vladimir; Vaganov, Eugene

    2016-04-01

    It is assumed that an annual tree-ring growth is adequately determined by a linear function of local or regional precipitation and temperature with a set of coefficients that are temporally invariant. But often that relations are non-linear. The process-based tree-ring VS-model can be used to resolve the critical processes linking climate variables to tree-ring formation. This work describes a new block of VS-model which allows to estimate a cell production in tree rings and transfer it into time scale based on the simulated integral growth rates of the model. In the algorithm of time identification for cell production we used a integral growth rates simulated by the VS-model for each growing season. The obtained detailed approach with a calculation of the time of each cell formation improves significantly the date accuracy of new cell formation in growing season. As a result for each cell in the tree-ring we estimate the temporal moment of the cell production corresponded to the seasonal growth rate in the same time scale. The approach was applied and tested for the cell measurements obtained for Scots pine (Pinus sylvestris) for the period 1964-2013 in Malaya Minusa river (Khakassia, South Siberia). The work was supported by the Russian Science Foundation (RSF # 14-14-00219)

  12. Time scale hierarchies in the functional organization of complex behaviors.

    PubMed

    Perdikis, Dionysios; Huys, Raoul; Jirsa, Viktor K

    2011-09-01

    Traditional approaches to cognitive modelling generally portray cognitive events in terms of 'discrete' states (point attractor dynamics) rather than in terms of processes, thereby neglecting the time structure of cognition. In contrast, more recent approaches explicitly address this temporal dimension, but typically provide no entry points into cognitive categorization of events and experiences. With the aim to incorporate both these aspects, we propose a framework for functional architectures. Our approach is grounded in the notion that arbitrary complex (human) behaviour is decomposable into functional modes (elementary units), which we conceptualize as low-dimensional dynamical objects (structured flows on manifolds). The ensemble of modes at an agent's disposal constitutes his/her functional repertoire. The modes may be subjected to additional dynamics (termed operational signals), in particular, instantaneous inputs, and a mechanism that sequentially selects a mode so that it temporarily dominates the functional dynamics. The inputs and selection mechanisms act on faster and slower time scales then that inherent to the modes, respectively. The dynamics across the three time scales are coupled via feedback, rendering the entire architecture autonomous. We illustrate the functional architecture in the context of serial behaviour, namely cursive handwriting. Subsequently, we investigate the possibility of recovering the contributions of functional modes and operational signals from the output, which appears to be possible only when examining the output phase flow (i.e., not from trajectories in phase space or time). PMID:21980278

  13. Time Scale Hierarchies in the Functional Organization of Complex Behaviors

    PubMed Central

    Perdikis, Dionysios; Huys, Raoul; Jirsa, Viktor K.

    2011-01-01

    Traditional approaches to cognitive modelling generally portray cognitive events in terms of ‘discrete’ states (point attractor dynamics) rather than in terms of processes, thereby neglecting the time structure of cognition. In contrast, more recent approaches explicitly address this temporal dimension, but typically provide no entry points into cognitive categorization of events and experiences. With the aim to incorporate both these aspects, we propose a framework for functional architectures. Our approach is grounded in the notion that arbitrary complex (human) behaviour is decomposable into functional modes (elementary units), which we conceptualize as low-dimensional dynamical objects (structured flows on manifolds). The ensemble of modes at an agent’s disposal constitutes his/her functional repertoire. The modes may be subjected to additional dynamics (termed operational signals), in particular, instantaneous inputs, and a mechanism that sequentially selects a mode so that it temporarily dominates the functional dynamics. The inputs and selection mechanisms act on faster and slower time scales then that inherent to the modes, respectively. The dynamics across the three time scales are coupled via feedback, rendering the entire architecture autonomous. We illustrate the functional architecture in the context of serial behaviour, namely cursive handwriting. Subsequently, we investigate the possibility of recovering the contributions of functional modes and operational signals from the output, which appears to be possible only when examining the output phase flow (i.e., not from trajectories in phase space or time). PMID:21980278

  14. Flow excursion time scales in the advanced neutron source reactor

    SciTech Connect

    Sulfredge, C.D.

    1995-04-01

    Flow excursion transients give rise to a key thermal limit for the proposed Advanced Neutron Source (ANS) reactor because its core involves many parallel flow channels with a common pressure drop. Since one can envision certain accident scenarios in which the thermal limits set by flow excursion correlations might be exceeded for brief intervals, a key objective is to determine how long a flow excursion would take to bring about a system failure that could lead to fuel damage. The anticipated time scale for flow excursions has been examined by subdividing the process into its component phenomena: bubble nucleation and growth, deceleration of the resulting two-phase flow, and finally overcoming thermal inertia to heat up the reactor fuel plates. Models were developed to estimate the time required for each individual stage. Accident scenarios involving sudden reduction in core flow or core exit pressure have been examined, and the models compared with RELAP5 output for the ANS geometry. For a high-performance reactor like the ANS, flow excursion time scales were predicted to be in the millisecond range, so that even very brief transients might lead to fuel damage. These results should prove useful whenever one must determine the time involved in any portion of a flow excursion transient.

  15. Redescription of Bellerophon asiaticus Wirth (Early Triassic: Gastropoda) from China, and a survey of Triassic Bellerophontacea.

    USGS Publications Warehouse

    Yochelson, E.Y.; Yin, Hongfu

    1985-01-01

    The bilaterally symmetrical gastropod Bellerophon asiaticus Wirth is redescribed from specimens collected in Guizhou Province, PRC. The species is reassigned to Retispira, a common late Paleozoic taxon. Retispira is another example of a Paleozoic gastropod genus that crossed the era boundary. Associated pelecypods that date these Guizhou occurrences as Early Triassic are well known species in PRC and are illustrated. Both Bellerophon and Euphemites probably occur in the Early Triassic, though the quality of illustrations leaves some uncertainty; the existence of Stachella in the Triassic is more problematic. There was no dramatic reduction of the Bellerophontacea from their abundance and diversity in the Permian. It may be a general phenomenon that most late Paleozoic family-level and many generic-level taxa of gastropods were unaffected by the late Permian 'crisis'. from Authors

  16. 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.

  17. The Role of Time-Scales in Socio-hydrology

    NASA Astrophysics Data System (ADS)

    Blöschl, Günter; Sivapalan, Murugesu

    2016-04-01

    Much of the interest in hydrological modeling in the past decades revolved around resolving spatial variability. With the rapid changes brought about by human impacts on the hydrologic cycle, there is now an increasing need to refocus on time dependency. We present a co-evolutionary view of hydrologic systems, in which every part of the system including human systems, co-evolve, albeit at different rates. The resulting coupled human-nature system is framed as a dynamical system, characterized by interactions of fast and slow time scales and feedbacks between environmental and social processes. This gives rise to emergent phenomena such as the levee effect, adaptation to change and system collapse due to resource depletion. Changing human values play a key role in the emergence of these phenomena and should therefore be considered as internal to the system in a dynamic way. The co-evolutionary approach differs from the traditional view of water resource systems analysis as it allows for path dependence, multiple equilibria, lock-in situations and emergent phenomena. The approach may assist strategic water management for long time scales through facilitating stakeholder participation, exploring the possibility space of alternative futures, and helping to synthesise the observed dynamics of different case studies. Future research opportunities include the study of how changes in human values are connected to human-water interactions, historical analyses of trajectories of system co-evolution in individual places and comparative analyses of contrasting human-water systems in different climate and socio-economic settings. Reference Sivapalan, M. and G. Blöschl (2015) Time scale interactions and the coevolution of humans and water. Water Resour. Res., 51, 6988-7022, doi:10.1002/2015WR017896.

  18. Feather-like development of Triassic diapsid skin appendages

    NASA Astrophysics Data System (ADS)

    Voigt, Sebastian; Buchwitz, Michael; Fischer, Jan; Krause, Daniel; Georgi, Robert

    2009-01-01

    Of the recent sauropsid skin appendage types, only feathers develop from a cylindrical epidermal invagination, the follicle, and show hierarchical branching. Fossilized integuments of Mesozoic diapsids have been interpreted as follicular and potential feather homologues, an idea particularly controversially discussed for the elongate dorsal skin projections of the small diapsid Longisquama insignis from the Triassic of Kyrgyzstan. Based on new finds and their comparison with the type material, we show that Longisquama’s appendages consist of a single-branched internal frame enclosed by a flexible outer membrane. Not supporting a categorization either as feathers or as scales, our analysis demonstrates that the Longisquama appendages formed in a two-stage, feather-like developmental process, representing an unusual early example for the evolutionary plasticity of sauropsid integument.

  19. Optimal Control Modification for Time-Scale Separated Systems

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan T.

    2012-01-01

    Recently a new optimal control modification has been introduced that can achieve robust adaptation with a large adaptive gain without incurring high-frequency oscillations as with the standard model-reference adaptive control. This modification is based on an optimal control formulation to minimize the L2 norm of the tracking error. The optimal control modification adaptive law results in a stable adaptation in the presence of a large adaptive gain. This study examines the optimal control modification adaptive law in the context of a system with a time scale separation resulting from a fast plant with a slow actuator. A singular perturbation analysis is performed to derive a modification to the adaptive law by transforming the original system into a reduced-order system in slow time. A model matching conditions in the transformed time coordinate results in an increase in the actuator command that effectively compensate for the slow actuator dynamics. Simulations demonstrate effectiveness of the method.

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

    SciTech Connect

    Bottiglieri, M.; Godano, C.; Lippiello, E.; Arcangelis, L. de

    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.

  1. Late Permian to Early Triassic magnetostratigraphy

    NASA Astrophysics Data System (ADS)

    Haag, Maja; Heller, Friedrich

    1991-10-01

    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 the late Palaeozoic to early Mesozoic. About 50% of the Permian samples from the Nammal section contain, hidden beneath a strong recent or Tertiary overprint, a characteristic remanent magnetization (ChRM) which is very likely of Permian age. This component, which was imprinted on the southern hemisphere, has normal as well as reversed polarity with a normal mean direction (Decl. = 289.3°, Incl. = -50.3°, α 95 = 4.3° , N = 113) which is in close agreement with the palaeofield direction expected for a site belonging to the Indian plate as part of Gondwanaland during the Permian. In the lower Upper Permian several normal polarity zones are recognized. This contradicts the current assumption that rocks of this age belong to the long, reversely polarized Kiaman hyperzone. The Kiaman interval must end and the Illawarra hyperzone of mixed polarity must begin in or prior to the lowermost Upper Permian. The Permian/Triassic boundary at Nammal as well as in the Chinese sections is situated very close to a transition from a reversed to a normal polarity zone. The Upper Permian at Nammal together with the Lower Triassic South China sections is estimated to cover about 20 Ma. Nearly 30 polarity changes are observed which result in an average reversal frequency very similar to that observed during the early Tertiary. The reversal rate after the end of the long-lasting reversed Kiaman hyperchron apparently increases in a manner similar to that after the end of the Cretaceous Long Normal Superchron. Only a few polarity zones are found in the lower Upper Permian

  2. Time Scale Optimization and the Hunt for Astronomical Cycles in Deep Time Strata

    NASA Astrophysics Data System (ADS)

    Meyers, Stephen R.

    2016-04-01

    A valuable attribute of astrochronology is the direct link between chronometer and climate change, providing a remarkable opportunity to constrain the evolution of the surficial Earth System. Consequently, the hunt for astronomical cycles in strata has spurred the development of a rich conceptual framework for climatic/oceanographic change, and has allowed exploration of the geologic record with unprecedented temporal resolution. Accompanying these successes, however, has been a persistent skepticism about appropriate astrochronologic testing and circular reasoning: how does one reliably test for astronomical cycles in stratigraphic data, especially when time is poorly constrained? From this perspective, it would seem that the merits and promise of astrochronology (e.g., a geologic time scale measured in ≤400 kyr increments) also serves as its Achilles heel, if the confirmation of such short rhythms defies rigorous statistical testing. To address these statistical challenges in astrochronologic testing, a new approach has been developed that (1) explicitly evaluates time scale uncertainty, (2) is resilient to common problems associated with spectrum confidence level assessment and 'multiple testing', and (3) achieves high statistical power under a wide range of conditions (it can identify astronomical cycles when present in data). Designated TimeOpt (for "time scale optimization"; Meyers 2015), the method employs a probabilistic linear regression model framework to investigate amplitude modulation and frequency ratios (bundling) in stratigraphic data, while simultaneously determining the optimal time scale. This presentation will review the TimeOpt method, and demonstrate how the flexible statistical framework can be further extended to evaluate (and optimize upon) complex sedimentation rate models, enhancing the statistical power of the approach, and addressing the challenge of unsteady sedimentation. Meyers, S. R. (2015), The evaluation of eccentricity

  3. Ti diffusion in quartz inclusions: implications for metamorphic time scales

    NASA Astrophysics Data System (ADS)

    Spear, Frank S.; Ashley, Kyle T.; Webb, Laura E.; Thomas, Jay B.

    2012-12-01

    Quartz inclusions in garnet from samples collected from the staurolite zone in central New England are zoned in cathodoluminescence (CL). The CL intensity is interpreted to be a proxy for Ti concentration and the zoning attributed to Ti diffusion into the quartz grains driven by Ti exchange between quartz and enclosing garnet as a function of changing temperature. The CL zoning has been interpreted using a numerical diffusion model to constrain the time scales over which the diffusion has occurred. Temperature-time histories are sensitive to the presumed peak temperature but not to other model parameters. The total time of the metamorphic heating and cooling cycle from around 450 °C to the peak temperature (550-600 °C) back to 450 °C is surprisingly short and encompasses only 0.2-2 million years for peak temperatures of 600-550 °C. The metamorphism was accompanied by large-scale nappe and dome formation, and it is suggested that this occurred as a consequence of in-sequence thrusting resulting in a mid-crustal ductile duplex structure.

  4. 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.

  5. Role of relaxation time scale in noisy signal transduction.

    PubMed

    Maity, Alok Kumar; Chaudhury, Pinaki; Banik, Suman K

    2015-01-01

    Intra-cellular fluctuations, mainly triggered by gene expression, are an inevitable phenomenon observed in living cells. It influences generation of phenotypic diversity in genetically identical cells. Such variation of cellular components is beneficial in some contexts but detrimental in others. To quantify the fluctuations in a gene product, we undertake an analytical scheme for studying few naturally abundant linear as well as branched chain network motifs. We solve the Langevin equations associated with each motif under the purview of linear noise approximation and derive the expressions for Fano factor and mutual information in close analytical form. Both quantifiable expressions exclusively depend on the relaxation time (decay rate constant) and steady state population of the network components. We investigate the effect of relaxation time constraints on Fano factor and mutual information to indentify a time scale domain where a network can recognize the fluctuations associated with the input signal more reliably. We also show how input population affects both quantities. We extend our calculation to long chain linear motif and show that with increasing chain length, the Fano factor value increases but the mutual information processing capability decreases. In this type of motif, the intermediate components act as a noise filter that tune up input fluctuations and maintain optimum fluctuations in the output. For branched chain motifs, both quantities vary within a large scale due to their network architecture and facilitate survival of living system in diverse environmental conditions. PMID:25955500

  6. Role of Relaxation Time Scale in Noisy Signal Transduction

    PubMed Central

    Maity, Alok Kumar; Chaudhury, Pinaki; Banik, Suman K

    2015-01-01

    Intra-cellular fluctuations, mainly triggered by gene expression, are an inevitable phenomenon observed in living cells. It influences generation of phenotypic diversity in genetically identical cells. Such variation of cellular components is beneficial in some contexts but detrimental in others. To quantify the fluctuations in a gene product, we undertake an analytical scheme for studying few naturally abundant linear as well as branched chain network motifs. We solve the Langevin equations associated with each motif under the purview of linear noise approximation and derive the expressions for Fano factor and mutual information in close analytical form. Both quantifiable expressions exclusively depend on the relaxation time (decay rate constant) and steady state population of the network components. We investigate the effect of relaxation time constraints on Fano factor and mutual information to indentify a time scale domain where a network can recognize the fluctuations associated with the input signal more reliably. We also show how input population affects both quantities. We extend our calculation to long chain linear motif and show that with increasing chain length, the Fano factor value increases but the mutual information processing capability decreases. In this type of motif, the intermediate components act as a noise filter that tune up input fluctuations and maintain optimum fluctuations in the output. For branched chain motifs, both quantities vary within a large scale due to their network architecture and facilitate survival of living system in diverse environmental conditions. PMID:25955500

  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. 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

  9. Scaling in a Continuous Time Model for Biological Aging

    NASA Astrophysics Data System (ADS)

    de Almeida, R. M. C.; Thomas, G. L.

    In this paper, we consider a generalization to the asexual version of Penna model for biological aging, where we take a continuous time limit. The genotype associated to each individual is an interval of real numbers over which Dirac δ-functions are defined, representing genetically programmed diseases to be switched on at defined ages of the individual life. We discuss two different continuous limits for the evolution equation and two different mutation protocols, to be implemented during reproduction. Exact stationary solutions are obtained and scaling properties are discussed.

  10. Time-Dependent Earthquake Forecasts on a Global Scale

    NASA Astrophysics Data System (ADS)

    Rundle, J. B.; Holliday, J. R.; Turcotte, D. L.; Graves, W. R.

    2014-12-01

    We develop and implement a new type of global earthquake forecast. Our forecast is a perturbation on a smoothed seismicity (Relative Intensity) spatial forecast combined with a temporal time-averaged ("Poisson") forecast. A variety of statistical and fault-system models have been discussed for use in computing forecast probabilities. An example is the Working Group on California Earthquake Probabilities, which has been using fault-based models to compute conditional probabilities in California since 1988. An example of a forecast is the Epidemic-Type Aftershock Sequence (ETAS), which is based on the Gutenberg-Richter (GR) magnitude-frequency law, the Omori aftershock law, and Poisson statistics. The method discussed in this talk is based on the observation that GR statistics characterize seismicity for all space and time. Small magnitude event counts (quake counts) are used as "markers" for the approach of large events. More specifically, if the GR b-value = 1, then for every 1000 M>3 earthquakes, one expects 1 M>6 earthquake. So if ~1000 M>3 events have occurred in a spatial region since the last M>6 earthquake, another M>6 earthquake should be expected soon. In physics, event count models have been called natural time models, since counts of small events represent a physical or natural time scale characterizing the system dynamics. In a previous research, we used conditional Weibull statistics to convert event counts into a temporal probability for a given fixed region. In the present paper, we move belyond a fixed region, and develop a method to compute these Natural Time Weibull (NTW) forecasts on a global scale, using an internally consistent method, in regions of arbitrary shape and size. We develop and implement these methods on a modern web-service computing platform, which can be found at www.openhazards.com and www.quakesim.org. We also discuss constraints on the User Interface (UI) that follow from practical considerations of site usability.