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Sample records for kyr revising earlier

  1. 75 FR 47316 - National Science Board; Sunshine Act Meetings; Notice (Subject Matter Revised From Earlier Notice)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-05

    ... National Science Board; Sunshine Act Meetings; Notice (Subject Matter Revised From Earlier Notice) The... National Science Board business and other matters specified, as follows: Date and Time: August 12, 2010, at 3 p.m. EDT. Subject Matter: Review and Discussion of Current Mid-Scale Research Funding Support...

  2. Which 100-kyr Cycle?

    NASA Astrophysics Data System (ADS)

    Berger, A.; Loutre, M. F.; Mélice, J. L.

    The origin of all the fundamental frequencies characterising the long term variations of the astronomical parameters has been identified. This allows to discuss their inter- relationship and possible changes in times. Different sources for the so-called 100-kyr cycle have been found in the astronomical parameters and in the insolation itself. The most popular 100-kyr cycle is certainly the eccentricity one. Actually, the periods of the most important spectral components of e used in Berger (1978) are 412 885, 14 945, 123 297, 99 590 and 131 248 yr. Instability of the resulting average 100-kyr cy- cle has been shown related to the ~ 400-kyr cycle. The derivative of eccentricity is definitely showing a spectrum dominated by the 100-kyr cycle with the same spectral components as e itself. The inclination of the Earth orbital plane on the ecliptic does not display any 100-kyr cycle, but it is not the case for its inclination on the reference plane for which cycles of 98 046 and 107 478 years appear. Finally the frequency modulation of obliquity is characterised by cycles 171 kyr and 97 kyr long. For inso- lation, it is known that there is only a very weak signal around 100-kyr coming from e itself. However, if we consider the seasonal cycle at the equator, its amplitude varies with cycles of 400 kyr, 100 kyr, 41 kyr, 10 kyr and 5 kyr, all related to e. Although all these cycles are close to the 100 kyr cycle found in geological data, the origin of this kind of cycle can be best identified by comparing the proxy record to the re- sponse of the climate system to the astronomical forcing. This forcing signal which contains, in one way or another, the astronomical characteristics mentioned above is, at least, partly distorted and transformed, a modification which can only be estimated through climate models. Such a climate model has been developed in the early 80Ss in Louvain-la-Neuve and used since to simulate the last and next glacial-interglacial cycles.

  3. Revision of Ernst Antevs' New England Varve Chronology: A Record of Meltwater Production and Southeastern LIS Recession: 18.2-12.5 kyr BP (Invited)

    NASA Astrophysics Data System (ADS)

    Ridge, J. C.

    2013-12-01

    New varve cores and 54 radiocarbon ages, have allowed the correction, closure of a gap, calibration, and expansion of Ernst Antevs' (1922) New England Varve Chronology from sediments of glacial Lake Hitchcock and it's successors in the Connecticut Valley of western New England (northeastern U.S.A.). The continuous 5659-yr chronology (18.2-12.5 kyr BP) has been renumbered as the North American Varve Chronology. Glacial varve thickness (18.2-13.7 kyr BP) documents abrupt changes in meltwater production related to varying ablation rate (summer climate) that is linked to ice sheet recession rates and advances, i.e. cold intervals are times of thin varves and slower ice recession or glacial readvances. To take advantage of the varve-climate relationship it is necessary to identify non-climatic events that can cause varve thickness to change. This includes sudden changes in lake level and flood events triggered by the abrupt drainage of tributary glacial lakes. A chronology of ice recession for intervals terminated by four stillstands and readvances of 1-2 century durations have been determined for the Connecticut Valley (from S to N): 50-100 m/yr in northern Connecticut to southern Massachusetts; Chicopee Readvance; 30-40 m/yr in central Mass.; Hatfield event; 80-90 m/yr from northern Mass. to central New Hampshire; North Charlestown end moraines; 300 m/yr to northern N.H.; Littleton Readvance; >300 m/yr to Quebec. Meltwater produced by ice recession of 300 m/yr modeled as a receding 1-bar ice sheet profile (from 100 km up ice near ELA to margin, valley width of 80 km, glacier flow rate of 200 m/yr at ELA) would be a minimum glacial meltwater discharge in the Connecticut Valley of ~90 x 109 m3/yr. This is ~10X the modern Conn. River discharge at Walpole, NH compressed almost entirely to the melt season. Non-glacial varves deposited after ice receded from the basin (13.7-12.5 kyr BP) also document climate change as a result of varve thickness varying with changes in

  4. The Sima de los Huesos hominids date to beyond U/Th equilibrium (>350 kyr) and perhaps to 400-500 kyr: New radiometric dates

    USGS Publications Warehouse

    Bischoff, J.L.; Shamp, D.D.; Aramburu, Arantza; Arsuaga, J.L.; Carbonell, E.; Bermudez de Castro, Jose Maria

    2003-01-01

    The Sima de los Huesos site of the Atapuerca complex near Burgos, Spain contains the skeletal remains of at least 28 individuals in a mud breccia underlying an accumulation of the Middle Pleistocene cave bear (U. deningeri). Earlier dating estimates of 200 to 320 kyr were based on U-series and ESR methods applied to bones, made inaccurate by unquantifiable uranium cycling. We report here on a new discovery within the Sima de los Huesos of human bones stratigraphically underlying an in situ speleothem. U-series analyses of the speleothem shows the lower part to be at isotopic U/Th equilibrium, translating to a firm lower limit of 350 kyr for the SH hominids. Finite dates on the upper part suggest a speleothem growth rate of c. 1 cm/32 kyr. This rate, along with paleontological constraints, place the likely age of the hominids in the interval of 400 to 600 kyr. ?? 2002 Elsevier Science Ltd. All rights reserved.

  5. An earlier de motu cordis.

    PubMed Central

    Daly, Walter J.

    2004-01-01

    Thirteenth century medical science, like medieval scholarship in general, was directed at reconciliation of Greek philosophy/science with prevailing medieval theology and philosophy. Peter of Spain [later Pope John XXI] was the leading medical scholar of his time. Peter wrote a long book on the soul. Imbedded in it was a chapter on the motion of the heart. Peter's De Motu was based on his own medical experience and Galen's De Usu Partium and De Usu Respirationis and De Usu Pulsuum. This earlier De Motu defines a point on the continuum of intellectual development leading to us and into the future. Thirteenth century scholarship relied on past authority to a degree that continues to puzzle and beg explanation. Images Fig. 1 PMID:17060956

  6. Modelling The Magnitude of Climatic Changes In East Africa During The Last 150 Kyr

    NASA Astrophysics Data System (ADS)

    Bergner, A. G. N.; Duehnforth, M.; Strecker, M. R.; Trauth, M. H.

    In order to assess the links between hydrology and climate in continental basins, water- balance modelling of lakes is a useful tool, because lakes are sensitive recorders of hydrologic fluctuations due to regional climate change. In the Central Kenya Rift, 40Ar/39Ar- dated lake sediments from the Naivasha and Nakuru-Elmenteita basins provide detailed information on extent and chronology of environmental changes and their effect on paleo-lakes. Mapping of lake deposits in surface outcrops and boreholes suggests that the extent of the lakes was comparable during highstands at 9 and 138 kyr BP, respectively, but significantly different compared to present conditions. Whereas the present Lake Naivasha (180 km2), Nakuru (40 km2) and Elmenteita (26 km2) have a water volume < 1 km3, paleo-lake areas were larger by factor of 3 to 4, and lake volumes increased by factor of 50 to 60. Simultaneously, these lakes were subject to considerable hydrochemical changes. For example, diatom and authigenic mineral assemblages indicate pH fluctuations between 7 and 11 for Lake Naivasha during the last 150 kyr, in contrast to a pH of 8.2. Hydroclimatic lake-balance modelling of the most prominent lake phases of Lake Naivasha and Lake Nakuru-Elmenteita were performed in order to compare past and present-day climate conditions. Our results show that a +15% increase in precipitation compared to modern values may have been responsible for a lake-level highstand at 9 kyr BP. In addition, the increase in precipitation may reach as much as +30% if a change in vegetation due to increased humidity in the catchment is taken into account. Preliminary modelling results for an earlier highstand of Lake Naivasha at 138 kyr BP suggests hydroclimatic conditions comparable to the Holocene highstand. From the analysis of lake sediments we infer that Lake Nakuru-Elmenteita also experienced significant lake highstands at 138 kyr BP most probably caused by the same wetter cli- mate conditions. Our

  7. Variations in flow and transport in thick desert vadose zones in response to paleoclimatic forcing (0-90 kyr): Field measurements, modeling, and uncertainties

    USGS Publications Warehouse

    Scanlon, B.R.; Keese, K.; Reedy, R.C.; Simunek, J.; Andraski, B.J.

    2003-01-01

    An understanding of unsaturated flow and potential recharge in interdrainage semiarid and arid regions is critical for quantification of water resources and contaminant transport. We evaluated system response to paleoclimatic forcing using water potential and Cl profiles and modeling of nonisothermal liquid and vapor flow and Cl transport at semiarid (High Plains, Texas) and arid (Chihuahuan Desert, Texas; Amargosa Desert, Nevada) sites. Infiltration in response to current climatic forcing is restricted to the shallow (???0.3-3 m) subsurface. Subsurface Cl accumulations correspond to time periods of 9-90 kyr. Bulge-shaped Cl profiles generally represent accumulation during the Holocene (9-16 kyr). Lower Cl concentrations at depth reflect higher water fluxes (0.04-8.4 mm/yr) during the Pleistocene and earlier times. Low water potentials and upward gradients indicate current drying conditions. Nonisothermal liquid and vapor flow simulations indicate that upward flow for at least 1-2 kyr in the High Plains and for 1.2-16 kyr at the Chihuahuan and Amargosa desert sites is required to reproduce measured upward water potential gradients and that recharge is negligible (<0.1 mm/yr) in these interdrainage areas.

  8. Does ice accretion temperature and geothernmal heating pace the change from ~40 kyr to ~100 kyr glacial cycles?

    NASA Astrophysics Data System (ADS)

    Buck, W. R.

    2008-12-01

    The growth and decay of ice sheets are clearly linked to cycles of the Earth's orbit, particularly the ~41 kyr obliquity cycle. Early Pleistocene ice ages appear to have grown and decayed on a timescale close to the obliquity period, while the period for late Pleistocene ice ages averages closer to 100 kyr. The thermal state of an ice sheet may control whether the climatic changes produced by orbital changes are can lead to the termination of an ice age. Numerous model studies indicate that the termination of ice ages requires glacial flow that is faster than expected for cold-based ice sheets. Fast flow likely requires that the base of the ice sheet be partially melted. Large ice sheets probably accrete cold, but geothermal heating can melt the base of an ice sheet if the surface of the ice is not too cold (as it may be in Antarctica) or if the accretion rate is not too high (as it may be in Greenland). The timescale for basal melting depends on the initial temperature structure of the ice sheet and on the rate of geothermal heating. For example the melting timescale depends on the square of the initial temperature of the ice sheet base. Although some workers assume parameters that give a melting timescale of less than 10 kyrs, reasonable values of ice temperature and terrestrial heatflow could give a timescale several times longer. One-dimensional numerical ice sheet flow models with a rate of ice accretion/ablation paced at 41 kyrs show a periodicity of the glacial cycles that depends on the period of basal melting. If the melting period is short (say <~30 kyrs) then the base of the ice sheet will be partially melted in time for the obliquity maximum that could produce a termination. The ice sheet then disappears at this first obliquity maximum after ice sheet initiation because it can flow fast enough to melt at lower latitudes and elevations. For longer basal melting periods the entire ice sheet may not be warm enough to flow fast enough to lead to termination

  9. Calcium isotopes in caves as a proxy for aridity: Modern calibration and application to the 8.2 kyr event

    NASA Astrophysics Data System (ADS)

    Owen, R. A.; Day, C. C.; Hu, C.-Y.; Liu, Y.-H.; Pointing, M. D.; Blättler, C. L.; Henderson, G. M.

    2016-06-01

    We present the first study of Ca isotope cycling in a natural cave system, with measurements of bedrock, dripwater and recently formed carbonate, coupled to a first stalagmite time-series spanning the 8.2 kyr event. Dripwaters at Heshang Cave (Central China; 30°27‧N, 110°25‧E) are isotopically heavy relative to the dolomite bedrock, the result of prior calcite precipitation (PCP) occurring earlier in the drip flow path. A simple Rayleigh fractionation model quantifies the extent of PCP in the modern environment at 36% Ca removal. The observed in situ calcium isotope fractionation factor between dripwater and carbonate is Δ 44 / 42 Ca = - 0.63 ± 0.03 ‰ and does not vary during the annual cycle. Measurements of speleothem carbonate spanning the 8.2 kyr event show the response of Ca isotopes to changing climate. δ44/42Ca increases by 0.35‰ at the onset of the event, coeval with changes in δ18O and Mg/Ca, and remains high for 80 yr. This change is explained by decreased rainfall leading to increased PCP; an interpretation supported by established PCP proxies (Mg/Ca, Sr/Ca and Ba/Ca). Ca isotopes indicate that PCP increased to 60% Ca removal during the event, which, from application of a simple box model, suggests mean annual rainfall decreased by approximately a third in Central China during the 8.2 kyr event. The response of Ca isotopes across this event demonstrates their potential for the assessment of past conditions, including past dripwater flow rates and rainfall.

  10. Late Neogene East Asian monsoon: from winter to summer dominated sub-regime and periodicity transition from 100 kyr to 41 kyr

    NASA Astrophysics Data System (ADS)

    Li, F.; Rousseau, D.-D.; Wu, N.; Hao, Q.; Pei, Y.

    2009-04-01

    More and more evidence indicates that the onset of the East Asian (EA) monsoon can be traced back to the Oligocene-Miocene boundary (at about 23 Ma). However, the process of its evolution is still less well known until now. Here we investigate its late Neogene evolution by analyzing a terrestrial mollusk sequence, from the Chinese Loess Plateau (CLP), covering the period between 7.1 and 3.5 Ma. Considering the modern ecological requirements of these organisms, we were able to define two groups of cold-aridiphilous (CA) and thermo-humidiphilous (TH) species, representing the EA winter and summer monsoon variations, respectively, as previously defined in the Quaternary glacial-interglacial cycles. Variations in these two groups indicate two different monsoon dominated periods during 7.1-3.5 Ma. First, between 7.1 and 5.5 Ma, the EA winter monsoon, with a 100 kyr periodicity, was dominant. Second, between 5.1 and 4 Ma, the EA summer monsoon dominated, with a 41 kyr periodicity. Furthermore, our mollusk record yields valuable evidence for a late Miocene-Pliocene transition of about 400 kyr from winter monsoon dominated towards summer monsoon dominated, associated with a periodicity transition from weak 100 kyr to 41 kyr. The strengthened winter monsoon interval, with a 100 kyr periodicity, is coeval with orbital-scale global ice volume changes, in conjunction with the uplift of the Tibetan Plateau which probably reinforced the winter monsoon sub-regime. Conversely, closures of the Panama and Indonesian seaways, associated with changes in obliquity between 5.1 and 4 Ma, are probably major forcing factors for the observed dominant summer monsoon with 41 kyr frequency, favoring heat and moisture transports between low and high latitudes to allow TH mollusks to grow and develop in the CLP. The transition from a 100 kyr dominated interval towards a 41 kyr dominated one is contrary to the mid-Pleistocene transition (MPT), which corresponds to ice volume expansion at high

  11. Earlier snowmelt and warming lead to earlier but not necessarily more plant growth.

    PubMed

    Livensperger, Carolyn; Steltzer, Heidi; Darrouzet-Nardi, Anthony; Sullivan, Patrick F; Wallenstein, Matthew; Weintraub, Michael N

    2016-01-01

    Climate change over the past ∼50 years has resulted in earlier occurrence of plant life-cycle events for many species. Across temperate, boreal and polar latitudes, earlier seasonal warming is considered the key mechanism leading to earlier leaf expansion and growth. Yet, in seasonally snow-covered ecosystems, the timing of spring plant growth may also be cued by snowmelt, which may occur earlier in a warmer climate. Multiple environmental cues protect plants from growing too early, but to understand how climate change will alter the timing and magnitude of plant growth, experiments need to independently manipulate temperature and snowmelt. Here, we demonstrate that altered seasonality through experimental warming and earlier snowmelt led to earlier plant growth, but the aboveground production response varied among plant functional groups. Earlier snowmelt without warming led to early leaf emergence, but often slowed the rate of leaf expansion and had limited effects on aboveground production. Experimental warming alone had small and inconsistent effects on aboveground phenology, while the effect of the combined treatment resembled that of early snowmelt alone. Experimental warming led to greater aboveground production among the graminoids, limited changes among deciduous shrubs and decreased production in one of the dominant evergreen shrubs. As a result, we predict that early onset of the growing season may favour early growing plant species, even those that do not shift the timing of leaf expansion. PMID:27075181

  12. Earlier snowmelt and warming lead to earlier but not necessarily more plant growth

    PubMed Central

    Livensperger, Carolyn; Steltzer, Heidi; Darrouzet-Nardi, Anthony; Sullivan, Patrick F.; Wallenstein, Matthew; Weintraub, Michael N.

    2016-01-01

    Climate change over the past ∼50 years has resulted in earlier occurrence of plant life-cycle events for many species. Across temperate, boreal and polar latitudes, earlier seasonal warming is considered the key mechanism leading to earlier leaf expansion and growth. Yet, in seasonally snow-covered ecosystems, the timing of spring plant growth may also be cued by snowmelt, which may occur earlier in a warmer climate. Multiple environmental cues protect plants from growing too early, but to understand how climate change will alter the timing and magnitude of plant growth, experiments need to independently manipulate temperature and snowmelt. Here, we demonstrate that altered seasonality through experimental warming and earlier snowmelt led to earlier plant growth, but the aboveground production response varied among plant functional groups. Earlier snowmelt without warming led to early leaf emergence, but often slowed the rate of leaf expansion and had limited effects on aboveground production. Experimental warming alone had small and inconsistent effects on aboveground phenology, while the effect of the combined treatment resembled that of early snowmelt alone. Experimental warming led to greater aboveground production among the graminoids, limited changes among deciduous shrubs and decreased production in one of the dominant evergreen shrubs. As a result, we predict that early onset of the growing season may favour early growing plant species, even those that do not shift the timing of leaf expansion. PMID:27075181

  13. Terrestrial biosphere changes over the last 120 kyr

    NASA Astrophysics Data System (ADS)

    Hoogakker, B. A. A.; Smith, R. S.; Singarayer, J. S.; Marchant, R.; Prentice, I. C.; Allen, J. R. M.; Anderson, R. S.; Bhagwat, S. A.; Behling, H.; Borisova, O.; Bush, M.; Correa-Metrio, A.; de Vernal, A.; Finch, J. M.; Fréchette, B.; Lozano-Garcia, S.; Gosling, W. D.; Granoszewski, W.; Grimm, E. C.; Grüger, E.; Hanselman, J.; Harrison, S. P.; Hill, T. R.; Huntley, B.; Jiménez-Moreno, G.; Kershaw, P.; Ledru, M.-P.; Magri, D.; McKenzie, M.; Müller, U.; Nakagawa, T.; Novenko, E.; Penny, D.; Sadori, L.; Scott, L.; Stevenson, J.; Valdes, P. J.; Vandergoes, M.; Velichko, A.; Whitlock, C.; Tzedakis, C.

    2016-01-01

    A new global synthesis and biomization of long (> 40 kyr) pollen-data records is presented and used with simulations from the HadCM3 and FAMOUS climate models and the BIOME4 vegetation model to analyse the dynamics of the global terrestrial biosphere and carbon storage over the last glacial-interglacial cycle. Simulated biome distributions using BIOME4 driven by HadCM3 and FAMOUS at the global scale over time generally agree well with those inferred from pollen data. Global average areas of grassland and dry shrubland, desert, and tundra biomes show large-scale increases during the Last Glacial Maximum, between ca. 64 and 74 ka BP and cool substages of Marine Isotope Stage 5, at the expense of the tropical forest, warm-temperate forest, and temperate forest biomes. These changes are reflected in BIOME4 simulations of global net primary productivity, showing good agreement between the two models. Such changes are likely to affect terrestrial carbon storage, which in turn influences the stable carbon isotopic composition of seawater as terrestrial carbon is depleted in 13C.

  14. Frequency variations of the earth's obliquity and the 100-kyr ice-age cycles

    NASA Technical Reports Server (NTRS)

    Liu, Han-Shou

    1992-01-01

    Changes in the earth's climate are induced by variations in the earth's orbital parameters which modulate the seasonal distribution of solar radiation. Periodicities in the geological climate record with cycles of 100, 41, and 23 kyr have been linked with changes in obliquity, eccentricity, and precession of the equinoxes. The effect of variations of eccentricity during a 100 kyr period is weak relative to the signals from obliquity and precession variations and it may therefore be expected that the 100 kyr signal in the climate record would be of low intensity. However, this signal dominates the climate record and internal nonlinear processes within the climate system have previously been proposed to account for this fact. The author shows that variations in the frequency of the obliquity cycle can give rise to strong 100-kyr forcing of climate.

  15. Revised age estimates of Brunhes palaeomagnetic events - Support for a link between geomagnetism and eccentricity

    NASA Technical Reports Server (NTRS)

    Rampino, M. R.

    1981-01-01

    Revisions in the dates of reported geomagnetic excursions during the Brunhes Epoch are proposed in light of possible correlations between a section at Gioia Tauro, Italy, deep-sea cores, a core from Lake Biwa, Japan, and some lava flows. The anomalously long, double Blake Event reported at Gioia Tauro is here correlated with the Blake Event (approximately 110 kyr) and the Biwa 1 event (180 plus or minus 5 kyr); an hiatus may be present in the section between these two events. The alpha event at Gioia Tauro is correlated with the Biwa 2 event at about 295 kyr; the beta event with the 'Biwa 3' event at about 400 kyr; the gamma event with the Snake River event at 480 plus or minus 50; and the delta event, not recorded elsewhere, is estimated to have occurred at approximately 620 kyr. These proposed refinements in the age estimates of the excursions suggest an approximately 100 kyr cyclicity. If the events are real and the revised dating is correct, the timing of the geomagnetic events seems to coincide with times of peak eccentricity of the earth's orbit, suggesting a causal connection.

  16. High temporal Resolution Fire History in Eastern Africa: the Last 16 kyr cal. BP

    NASA Astrophysics Data System (ADS)

    Vanniere, B.; Carcaillet, C.; Garcin, Y.; Vullien, A.; Williamson, D.

    2004-12-01

    Charcoal series, based on a high temporal resolution analysis, at Lake Massoko (9°20' S, 33° 45' E, 770 a.s.l., SW Tanzania) reveals numerous changes of fire regime over the last 16 kyr cal BP. Data are based on the tallying of charcoal from 700 continuous 1 cm thick samples along a 7m long sequence. The structure of charcoal particles is well preserved with an length:width ratio superior to 5; this appears to testify to the local provenance of the material studied and to the rapid transport of particles to the lake. The majority of particles belongs to herbaceous cuticles produced by savanna or bush fires. Time control is supported by 14 radiocarbon dates. Mean time resolution per sample of 17 yr provides the first long detailed biomass burning record in Africa. This record evidences frequent fires events during the last 16 kyr, indicating that fire is a key component of east African ecosystems since, at least, the last glacial stage up to present. From 16 to 12 kyr cal BP, the charcoal influx into the lake is low except during two specific sequences, between 13.5-12.5 kyr cal BP and 14.5-14 kyr cal BP. These may correspond to more arid or more biomass-available phases. Around 10 kyr cal BP, at the early Holocene a greater influx of charcoal is recorded in the lake, probably as a result of a high fire regime likely triggered by severe droughts. Between 8.3 and 1.7 kyr cal BP, the charcoal influx displays a cyclic fire history of ca. 500 yr. Low fire regime, between 3.5-2.5, 5.5-5 and 7.5-7 kyr cal BP, correspond to wetter periods. About 12 sequences of fire increase and decrease are highlighted, which appears to support a high climatic variability during the middle-Holocene. After 1.7 kyr BP, there is a long lasting increase of charcoal influx into the lake, as observed by black carbon analysis (Thevenon et al., 2003). This particular period, without analog since 16 kyr cal BP, is consistent with the development of Iron Age settlements in the region, slash

  17. Bottom-Water Oxygenation in the Central Gulf of California for the Last 16 kyrs

    NASA Astrophysics Data System (ADS)

    Karlin, R. E.; Harris, A.

    2006-12-01

    Laminated sediment records from the central Gulf of California reveal changes in oxygen-related microfabric, which can be directly related to variations in the intensity and location of the oxygen-minimum zone (OMZ) for the last 16,000 years. The intensity and location of the OMZ depends on the interaction of primary productivity and bottom water oxygen availability created by compositional variations and replenishment speed of Pacific Intermediate Water (PIW). Seven cores recovered from water depths ranging from 525 to 820 meters directly sample changes in the extent of the OMZ and PIW. Chronologies for six Atlantis II cores are based on independent radiocarbon ages, stratigraphic correlation, oxygen-isotope stratigraphy, and lamina counts from x-radiograph images. At DSDP Site 480, the varve chronology, when compared to an independent age model based on radiocarbon ages and secular variation curves, indicates that the Site 480 record is continuous and has an age error comparable to that of ice core and tree ring records. Bottom-water oxygenation was relatively higher from 17 to ~15.5 cal kyrs BP and ~12.3 to ~11.9 cal kyrs BP, was lower from ~15.5 to ~12.3 cal kyrs BP and ~11.6 to 7 cal kyrs and began increasing again after 7 cal kyrs. Changes in microfabric and, hence, bottom water oxygenation were not synchronous in the central Gulf. The change from oxic to more anoxic conditions near the end of the last glacial and the Younger Dryas began at depth and progressively shallowed with time. The transition to more oxic conditions in the Younger Dryas also began at depth and shallowed with time. The relationships between proxies for PIW oxygenation, primary productivity, and sediment flux suggest that productivity controlled bottom-water oxygenation from 17 to 11.6 cal kyrs BP. Lower oxygen availability due to less PIW input appears to have controlled bottom-water oxygenation from 11.6 to ~10 cal kyrs BP. No clear basin-wide relationship is found between productivity

  18. An 84-kyr paleomagnetic record from the sediments of Lake Baikal, Siberia

    USGS Publications Warehouse

    Peck, J.A.; King, J.W.; Colman, Steven M.; Kravchinsky, V.A.

    1996-01-01

    We have conducted a paleomagnetic study of sediment cores obtained from the Selenga prodelta region of Lake Baikal, Russia. This record, which spans approximately the last 84 kyr, contributes to a better understanding of the nature of geomagnetic field behavior in Siberia and is a useful correlation and dating tool. We demonstrate that the Lake Baikal sediments are recording variations in the geomagnetic field. The directional record displays secular variation behavior with a geomagnetic excursion at 20 ka and additional excursions appearing as large-amplitude secular variation at 41, 61, and 67 ka. Smoothing of the geomagnetic excursion behavior occurs in Lake Baikal sediments owing to the intermediate sedimentation rate (13 cm kyr-1). The Lake Baikal relative paleointensity record correlates to absolute paleointensity data for the last 10 kyr and to relative paleointensity records from the Mediterranean Sea and Indian Ocean for the last 84 kyr. This correlation suggests a strong global (i.e., dipole) component to these records and further supports the reliability of sediments as recorders of relative geomagnetic paleointensity. We show that a relative geomagnetic intensity stratigraphy has a potential resolution of 7 kyr by correlating continental and marine records. The geomagnetic intensity stratigraphy helps constrain the age of the difficult to date Lake Baikal sediments.

  19. 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.

  20. Scientific Knowledge Suppresses but Does Not Supplant Earlier Intuitions

    ERIC Educational Resources Information Center

    Shtulman, Andrew; Valcarcel, Joshua

    2012-01-01

    When students learn scientific theories that conflict with their earlier, naive theories, what happens to the earlier theories? Are they overwritten or merely suppressed? We investigated this question by devising and implementing a novel speeded-reasoning task. Adults with many years of science education verified two types of statements as quickly…

  1. δ13Catm and [CO2] measurements in Antarctic ice cores, 160 kyrBP - present

    NASA Astrophysics Data System (ADS)

    Eggleston, Sarah; Schmitt, Jochen; Schneider, Robert; Joos, Fortunat; Fischer, Hubertus

    2014-05-01

    Measurements from Antarctic ice cores allow us to reconstruct atmospheric concentrations of climatically important gases including CO2 over the past 800 kyr. Such measurements show that [CO2] has varied in parallel with Antarctic temperatures on glacial-interglacial timescales. Knowledge of the variations of the stable carbon isotope of CO2, δ13Catm, can help us better understand the processes involved in these fluctuations. Here, we present a first complete δ13Catmrecord extending from 160 kyrBP to the present accompanied by δ15N2 measurements during Marine Isotope Stage 3 (MIS 3, 57 - 29 kyrBP). The present record, measured primarily on ice from the EPICA Dome C and Talos Dome ice cores, has an average resolution of 500 yr, focused mainly on the Last Glacial Maximum and termination (180 yr; Schmitt et al., 2012), MIS 3 (660 yr), and Termination II through MIS 5.4 (590 yr; Schneider et al., 2013). Throughout the record, δ13Catm varies between approximately -6.8 and -6.4‰Following a period of relatively constant δ13Catm at the end of MIS 6 (around -6.8), the boundaries of MIS 5 correspond roughly with the beginning and end of a gradual enrichment in this isotope. In comparison, the more recent record depicts three more abrupt excursions to lighter values around 63 - 59, 46, and 17 kyrBP, in each case followed by a slower return (0.4o over the course of 5 - 15 kyr) to more enriched isotopic values. These coincide with Heinrich events 6, 5, and 1, respectively. No direct correlation is observed between the concentration and carbon isotope of CO2 over the last 160 kyr. The data indicate rather that numerous processes, such as uptake and release of atmospheric CO2 by the ocean and land biosphere, perhaps influenced by regions of growing permafrost during MIS 3 and 4, acting on a variety of timescales must be considered in explaining the evolution of δ13Catm on glacial-interglacial timescales. References: Schmitt, J. et al. Science 336, 711-714 (2012) Schneider

  2. Observation of 23 supernovae that exploded <300 pc from Earth during the past 300 kyr

    SciTech Connect

    Firestone, R. B.

    2014-07-01

    Four supernovae (SNe), exploding ≤300 pc from Earth, were recorded 44, 37, 32, and 22 kyr ago in the radiocarbon ({sup 14}C) record during the past 50 kyr. Each SN left a nearly identical signature in the record, beginning with an initial sudden increase in atmospheric radiocarbon, when the SN exploded, followed by a hiatus of 1500 yr, and concluding with a sustained 2000 yr increase in global radiocarbon due to γ-rays produced by diffusive shock in the SN remnant (SNR). For the past 18 kyr excess radiocarbon has decayed with the {sup 14}C half-life. SN22kyrBP, is identified as the Vela SN that exploded 250 ± 30 pc from Earth. These SN are confirmed in the {sup 10}Be, {sup 26}Al, {sup 36}Cl, and NO{sub 3}{sup −} geologic records. The rate of near-Earth SNe is consistent with the observed rate of historical SNe giving a galactic rate of 14 ± 3 kyr{sup –1} assuming the Chandra Galactic Catalog SNR distribution. The Earth has been used as a calorimeter to determine that ≈2 × 10{sup 49} erg were released as γ-rays at the time of each SN explosion and ≈10{sup 50} erg in γ-rays following each SN. The background rate of {sup 14}C production by cosmic rays has been determined as 1.61 atoms cm{sup –2} s{sup –1}. Approximately 1/3 of the cosmic ray energy produced by diffusive shock in the SNR was observed to be emitted as high-energy γ-rays. Analysis of the {sup 10}Be/{sup 9}Be ratio in marine sediment identified 19 additional near-Earth SNe that exploded 50-300 kyr ago. Comparison of the radiocarbon record with global temperature variations indicated that each SN explosion is correlated with a concurrent global warming of ≈3°C-4°C.

  3. A distal 140 kyr sediment record of Nile discharge and East African monsoon variability

    NASA Astrophysics Data System (ADS)

    Ehrmann, Werner; Schmiedl, Gerhard; Seidel, Martin; Krüger, Stefan; Schulz, Hartmut

    2016-03-01

    Clay mineral assemblages in a sediment core from the distal Nile discharge plume off Israel have been used to reconstruct the late Quaternary Nile sediment discharge into the eastern Mediterranean Sea (EMS). The record spans the last ca. 140 kyr. Smectite abundances indicate the influence of the Blue Nile and the Atbara River that have their headwaters in the volcanic rocks of the Ethiopian Highlands. Kaolinite abundances indicate the influence of wadis, which contribute periodically to the suspension load of the Nile. Due to the geographical position, the climate and the sedimentary framework of the EMS is controlled by two climate systems. The long-term climate regime was governed by the African monsoon that caused major African humid periods (AHPs) with enhanced sediment discharge at 132 to < 126 (AHP 5), 116 to 99 (AHP4), and 89 to 77 ka (AHP3). They lasted much longer than the formation of the related sapropel layers S5 (> 2 kyr), S4 (3.5 kyr), and S3 (5 kyr). During the last glacial period (Marine Isotope Stages (MISs) 4-2), the long-term changes in the monsoonal system were superimposed by millennial-scale changes in an intensified midlatitude glacial system. This climate regime caused short but pronounced drought periods in the Nile catchment, which are linked to Heinrich events and alternate with more humid interstadials. The clay mineral record further implies that feedback mechanisms between vegetation cover and sediment discharge of the Nile are detectable but of minor importance for the sedimentary record in the southeastern Mediterranean Sea during the investigated African humid periods.

  4. Causal links between Nile floods and eastern Mediterranean sapropel formation during the past 125 kyr confirmed by OSL and radiocarbon dating of Blue and White Nile sediments

    NASA Astrophysics Data System (ADS)

    Williams, M. A. J.; Duller, G. A. T.; Williams, F. M.; Woodward, J. C.; Macklin, M. G.; El Tom, O. A. M.; Munro, R. N.; El Hajaz, Y.; Barrows, T. T.

    2015-12-01

    It has long been hypothesised that beds of highly organic mud or sapropels seen in marine sediment cores retrieved from the floor of the eastern Mediterranean accumulated during times of high Nile fluvial discharge. Our recent fieldwork in the valleys of the Blue Nile, the White Nile and the main Nile has for the first time revealed a sequence of extreme flood episodes synchronous with sapropel units S5 (124 kyr), S4 (102 kyr), S3 (81 kyr), S2 (55 kyr) and S1 (13.5-6.5 kyr). There are more weakly defined links with Nile floods and sapropel units S9 (240 kyr), S8 (217 kyr), S7 (195 kyr), S6 (172 kyr), but the dating error terms are too large to allow us to be too definite. During times of extreme floods over the past 125 kyr, wide distributary channels of the Blue Nile flowed across the Gezira alluvial fan in central Sudan and transported a bed load of sand and gravel into the lower White Nile valley. The sands were reworked by wind to form source-bordering dunes, all of which contain heavy minerals of Ethiopian provenance. These source-bordering dunes were active at 115-105 kyr, 60 kyr and 12-7 kyr, all times of extreme Blue Nile floods. The flood and dune sediments were dated using a combination of optically stimulated luminescence (OSL) and radiocarbon analyses. The Quaternary record of Nile floods discussed here shows a precessional signal and reflects episodes of stronger summer monsoon and more northerly seasonal movement of the ITCZ, linked to times of higher insolation in northern tropical latitudes. Progressive aggradation of Holocene Nile channels in northern Sudan has had a profound influence upon human settlement in the last 8 kyr.

  5. Variations in subject pool as a function of earlier or later participation.

    PubMed

    Bernard, L

    2000-04-01

    Data were obtained from 113 participants in a university subject pool during a 16-wk. semester. Without knowing the purpose of the study, participants self-selected to participate earlier (Weeks 3 and 4: n = 63) or later (Weeks 15 or 16) n = 50). Variations in scores on the NEO Personality Inventory--Revised, the Crowne-Marlowe Social Desirability Scale, the General Expectancy of Success Scale, the Shipley Institute of Living Scale, self-reported SATs and GPAs, and a measure of academic self-efficacy as a function of earlier or later participation were examined. Multivariate analysis of variance indicated that early participants differed significantly from later participants but not in predicted ways. Earlier participants scored higher on NEO PI-R Neuroticism; specifically men (n = 15) and women (n = 48) scored higher on Hostility, and women scored higher on Depression and Self-consciousness. An additional significant difference occurred for self-reported SAT Verbal scores for men, which were significantly higher for later participants. These temporal variations may represent confounds in research using university subject pools. PMID:10840925

  6. Insolation-driven 100 kyr glacial cycles and millennial climate change

    NASA Astrophysics Data System (ADS)

    Abe-Ouchi, A.; Saito, F.; Kawamura, K.; Raymo, M. E.; Okuno, J.; Takahashi, K.; Blatter, H.

    2013-12-01

    The waxing and waning of Northern Hemisphere ice sheets over the past one million years is dominated by an approximately 100-kyr periodicity and a sawtooth pattern (gradual growth and fast termination). Milankovitch theory proposes that summer insolation at high northern latitudes drives the glacial cycles, and statistical tests demonstrated that the glacial cycles are indeed linked to eccentricity, obliquity and precession cycles. However, insolation alone cannot explain the strong 100 kyr cycle which presumably arises through internal climatic feedbacks. Prior work with conceptual models, for example, showed that glacial terminations are associated with the build-up of Northern Hemisphere 'excess ice', but the physical mechanisms of 100-kyr cycle at work remain unclear. Here, using comprehensive climate and ice sheet models, we show that the ~100-kyr periodicity is explained by insolation and internal feedback amongst the climate, ice sheet and lithosphere/asthenosphere system (reference). We found that equilibrium states of ice sheets exhibit hysteresis responses to summer insolation, and that the shape and position of the hysteresis loop play a key role in determining the periodicities of glacial cycles. The hysteresis loop of the North American ice sheet is such that, after its inception, the ice sheet mass balance remains mostly positive or neutral through several precession cycles whose amplitude decreases towards an eccentricity minimum. The larger the ice sheet grows and extends towards lower latitudes, the smaller is the insolation required to turn the mass balance to negative. Therefore, once the large ice sheet is established, only a moderate increase in insolation can trigger a negative mass balance, leading to a complete retreat within several thousand years, due to the delayed isostatic rebound. The effect of ocean circulation and millennial scale climate change are not playing the dominant role for determing the 100kyr cycle, but are effective for

  7. Research promises earlier warning for grapevine canker diseases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When it comes to detecting and treating vineyards for grapevine canker diseases (also called trunk diseases), like Botryosphaeria dieback (Bot canker), Esca, Eutypa dieback and Phomopsis dieback, the earlier the better, says plant pathologist Kendra Baumgartner, with the USDA’s Agricultural Research...

  8. Prescription stimulant use is associated with earlier onset of psychosis.

    PubMed

    Moran, Lauren V; Masters, Grace A; Pingali, Samira; Cohen, Bruce M; Liebson, Elizabeth; Rajarethinam, R P; Ongur, Dost

    2015-12-01

    A childhood history of attention deficit hyperactivity disorder (ADHD) is common in psychotic disorders, yet prescription stimulants may interact adversely with the physiology of these disorders. Specifically, exposure to stimulants leads to long-term increases in dopamine release. We therefore hypothesized that individuals with psychotic disorders previously exposed to prescription stimulants will have an earlier onset of psychosis. Age of onset of psychosis (AOP) was compared in individuals with and without prior exposure to prescription stimulants while controlling for potential confounding factors. In a sample of 205 patients recruited from an inpatient psychiatric unit, 40% (n = 82) reported use of stimulants prior to the onset of psychosis. Most participants were prescribed stimulants during childhood or adolescence for a diagnosis of ADHD. AOP was significantly earlier in those exposed to stimulants (20.5 vs. 24.6 years stimulants vs. no stimulants, p < 0.001). After controlling for gender, IQ, educational attainment, lifetime history of a cannabis use disorder or other drugs of abuse, and family history of a first-degree relative with psychosis, the association between stimulant exposure and earlier AOP remained significant. There was a significant gender × stimulant interaction with a greater reduction in AOP for females, whereas the smaller effect of stimulant use on AOP in males did not reach statistical significance. In conclusion, individuals with psychotic disorders exposed to prescription stimulants had an earlier onset of psychosis, and this relationship did not appear to be mediated by IQ or cannabis. PMID:26522870

  9. Earlier Guidance Opportunities: Priorities for the 1970's.

    ERIC Educational Resources Information Center

    Nemec, William E., Ed.

    "Earlier Guidance Opportunities (EGO): Priorities for the 1970's" was the topic for this Ohio Elementary Guidance Conference. In his keynote address entitled "New Perspectives on the Guidance of Younger Children - Can We Afford to Delay Vocational Guidance?" Dr. George E. Hill used EGO to say, "Education Gives Opportunity,""Ego's Grow on…

  10. High-latitude forcing of diatom productivity in the southern Agulhas Plateau during the past 350 kyr

    NASA Astrophysics Data System (ADS)

    Romero, O. E.; Kim, J.-H.; Bárcena, M. A.; Hall, I. R.; Zahn, R.; Schneider, R.

    2015-02-01

    The hydrography of the Indian-Atlantic Ocean gateway has been connected to high-latitude climate dynamics by oceanic and atmospheric teleconnections on orbital and suborbital timescales. A wealth of sedimentary records aiming at reconstructing the late Pleistocene paleoceanography around the southern African continent has been devoted to understanding these linkages. Most of the records are, however, clustered close to the southern South African tip, with comparatively less attention devoted to areas under the direct influence of frontal zones of the Southern Ocean/South Atlantic. Here we present data of the composition and concentration of the diatom assemblage together with bulk biogenic content and the alkenone-based sea surface temperature (SST) variations for the past 350 kyr in the marine sediment core MD02-2588 (approximately 41°S, 26°E) recovered from the southern Agulhas Plateau. Variations in biosiliceous productivity show a varying degree of coupling with Southern Hemisphere paleoclimate records following a glacial-interglacial cyclicity. Ecologically well-constrained groups of diatoms record the glacial-interglacial changes in water masses dynamics, nutrient availability, and stratification of the upper ocean. The good match between the glacial maxima of total diatoms concentration, Chaetoceros spores abundance, and opal content with the maximum seasonal cover of Antarctic ice and the atmospheric dust records points to a dominant Southern Hemisphere forcing of diatom production. Suborbital variability of SST suggests rapid latitudinal migrations of the Subtropical Front and associated water masses over the southern Agulhas Plateau, following millennial contractions and expansions of the subtropical gyres. Warmings of the upper ocean over site MD02-2588 during terminations IV to I occurred earlier than that in the Antarctic Vostok, which is indicative of a Northern Hemisphere lead. Our multiparameter reconstruction highlights how high

  11. Earlier green-up and spring warming amplification over Europe

    NASA Astrophysics Data System (ADS)

    Ma, Shaoxiu; Pitman, Andy J.; Lorenz, Ruth; Kala, Jatin; Srbinovsky, Jhan

    2016-03-01

    The onset of green-up of plants has advanced in response to climate change. This advance has the potential to affect heat waves via biogeochemical and biophysical processes. Here a climate model was used to investigate only the biophysical feedbacks of earlier green-up on climate as the biogeochemical feedbacks have been well addressed. Earlier green-up by 5 to 30 days amplifies spring warming in Europe, especially heat waves, but makes few differences to heat waves in summer. This spring warming is most noticeable within 30 days of advanced green-up and is associated with a decrease in low- and middle-layer clouds and associated increases of downward short wave and net radiation. We find negligible differences in the Southern Hemisphere and low latitudes of the Northern Hemisphere. Our results provide an estimate of the level of skill necessary in phenology models to avoid introducing biases in climate simulations.

  12. Constraint on the penultimate glacial maximum Northern Hemisphere ice topography (≈140 kyrs BP)

    NASA Astrophysics Data System (ADS)

    Colleoni, Florence; Wekerle, Claudia; Näslund, Jens-Ove; Brandefelt, Jenny; Masina, Simona

    2016-04-01

    The penultimate glacial maximum (PGM, ≈140 kyrs BP), is known to be the most extensive glaciation on record that occurred during the last 400 kyrs over Eurasia. We used a coupled Atmosphere-Ocean-Sea-Ice-Land model to simulate the climate of the PGM accounting for a reconstruction of the large PGM Eurasian ice sheet. Due to uncertainties in the PGM Laurentide ice-sheet topography, two simulations with different ice-sheet topographies over North America (large as for the Last Glacial Maximum, LGM and small as for 13 kyrs BP) are performed. Results show that the simulated PGM glacial maximum climates are of comparable magnitude with previous simulations of the LGM in both cases. Assuming a small Laurentide ice-sheet instead of the LGM one in our PGM simulations results in a shift in the planetary waves. This causes an increase in storm track activity over the North Atlantic as well as higher temperatures and precipitation rates over North America, North Atlantic and over the Eurasian ice sheet. In addition, it induces a negative temperature anomaly over East Siberia yielding a thick snow cover, which seems to be in agreement with data from recent Arctic campaigns suggesting that an ice cap developed over Beringia during the PGM. All together, the changes in large-scale circulation and regional climate simulated using a small Laurentide ice sheet match the proxies well. Based on our findings, we suggest that the Laurentide ice sheet might have been smaller during the PGM than during the LGM, in turn also implying a larger Eurasian ice sheet than during the LGM, which is supported by various geological evidence of the PGM.

  13. Hydrographic changes of the Southern Ocean (southeast Indian Sector) Over the last 230 kyr

    NASA Astrophysics Data System (ADS)

    Labeyrie, Laurent; Labracherie, Monique; Gorfti, Nabila; Pichon, Jean Jacques; Vautravers, Maryline; Arnold, Maurice; Duplessy, Jean-Claude; Paterne, Martine; Michel, Elizabeth; Duprat, Josette; Caralp, Michelle; Turon, Jean-Louis

    1996-02-01

    Hydrographical changes of the southern Indian Ocean over the last 230 kyr, is reconstructed using a 17-m-long sediment core (MD 88 770; 46°01'S 96°28'E, 3290m). The oxygen and carbon isotopic composition of planktonic (N. pachyderma sinistra and G. bulloides) and benthic (Cibicidoides wuellerstorfi, Epistominella exigua, and Melonis barleeanum) foraminifera have been analysed. Changes in sea surface temperatures (SST) are calculated using diatom and foraminiferal transfer functions. A new core top calibration for the Southern Ocean allows an extension of the method developed in the North Atlantic to estimate paleosalinities (Duplessy et al., 1991). The age scale is built using accelerator mass spectrometry (AMS) 14C dating of N. pachyderma s. for the last 35 kyr, and an astronomical age scale beyond. Changes in surface temperature and salinity clearly lead (by 3 to 7 kyr) deep water variations. Thus changes in deep water circulation are not the cause of the early response of the surface Southern Ocean to climatic changes. We suggest that the early warming and cooling of the Southern Ocean result from at least two processes acting in different orbital bands and latitudes: (1) seasonality modulated by obliquity affects the high-latitude ocean surface albedo (sea ice coverage) and heat transfer to and from the atmosphere; (2) low-latitude insolation modulated by precession influences directly the atmosphere dynamic and related precipitation/ evaporation changes, which may significantly change heat transfer to the high southern latitudes, through their control on latitudinal distribution of the major frontal zones and on the conditions of intermediate and deep water formation.

  14. The Liang Bua faunal remains: a 95k.yr. sequence from Flores, East Indonesia.

    PubMed

    van den Bergh, G D; Meijer, H J M; Due Awe, Rokhus; Morwood, M J; Szabó, K; van den Hoek Ostende, L W; Sutikna, T; Saptomo, E W; Piper, P J; Dobney, K M

    2009-11-01

    Excavations at Liang Bua, a limestone cave on the island of Flores, East Indonesia, have yielded a well-dated archaeological and faunal sequence spanning the last 95k.yr., major climatic fluctuations, and two human species -H. floresiensis from 95 to 17k.yr.(1), and modern humans from 11k.yr. to the present. The faunal assemblage comprises well-preserved mammal, bird, reptile and mollusc remains, including examples of island gigantism in small mammals and the dwarfing of large taxa. Together with evidence from Early-Middle Pleistocene sites in the Soa Basin, it confirms the long-term isolation, impoverishment, and phylogenetic continuity of the Flores faunal community. The accumulation of Stegodon and Komodo dragon remains at the site in the Pleistocene is attributed to Homo floresiensis, while predatory birds, including an extinct species of owl, were largely responsible for the accumulation of the small vertebrates. The disappearance from the sequence of the two large-bodied, endemic mammals, Stegodon florensis insularis and Homo floresiensis, was associated with a volcanic eruption at 17 ka and precedes the earliest evidence for modern humans, who initiated use of mollusc and shell working, and began to introduce a range of exotic animals to the island. Faunal introductions during the Holocene included the Sulawesi warty pig (Sus celebensis) at about 7ka, followed by the Eurasian pig (Sus scrofa), Long-tailed macaque, Javanese porcupine, and Masked palm civet at about 4ka, and cattle, deer, and horse - possibly by the Portuguese within historic times. The Holocene sequence at the site also documents local faunal extinctions - a result of accelerating human population growth, habitat loss, and over-exploitation. PMID:19058833

  15. Geomagnetic field intensity, North Atlantic Deep Water circulation and atmospheric Δ 14C during the last 50 kyr

    NASA Astrophysics Data System (ADS)

    Laj, Carlo; Kissel, Catherine; Mazaud, Alain; Michel, Elisabeth; Muscheler, Raimund; Beer, Juerg

    2002-06-01

    We present simulated records of past changes in the atmospheric Δ 14C for the last 50 kyr due to changes in geomagnetic field intensity and in the strength of the North Atlantic Deep Water (NADW). A new geomagnetic record was used, largely based on the NAPIS-75 record [Laj et al., Phil. Trans. R. Soc. London A 358 (2000) 1009-1025] which has been extended for the 0-20 kyr interval using archeomagnetic and volcanic data. Past changes of the NADW were derived from a mineral magnetic study of the cores used in the construction of NAPIS-75. Two box models of different complexity (4 and 17 boxes) were used to simulate the carbon cycle. Calculated records of Δ 14C are consistent with experimental determinations for the last 24 kyr. For older ages, the records calculated with variable oceanic circulation conditions reach values as high as 600‰ (with an average of 500‰) between 20 and 40 kyr with maxima around 21, 30 and 38 kyr (GISP2 age model), while low values are observed prior to 42 kyr. Although large inconsistencies in experimental data preclude precise comparison, the average record simulated with the 17-box model is overall consistent with the Icelandic Sea record [Voelker et al., Radiocarbon 40 (1998) 517-534; 42 (2000) 437-452], except for the extremely high peak observed in this record at 40.5 kyr. On the other hand, the results recently reported from a stalagmite recovered from a submerged cave in the Bahamas [Beck et al., Science 292 (2001) 2453-2458] are inconsistent with all our model simulations. In the 20-45 kyr interval, the improved geomagnetic record combined with the new NADW profile allows us to give a modeled evaluation of the relative contribution of these factors to changes in atmospheric Δ 14C. The average simulation provides a first order modeled correction for conventional radiocarbon ages older than 25 kyr for which no calibration curve is available as yet.

  16. Earlier vegetation green-up has reduced spring dust storms.

    PubMed

    Fan, Bihang; Guo, Li; Li, Ning; Chen, Jin; Lin, Henry; Zhang, Xiaoyang; Shen, Miaogen; Rao, Yuhan; Wang, Cong; Ma, Lei

    2014-01-01

    The observed decline of spring dust storms in Northeast Asia since the 1950s has been attributed to surface wind stilling. However, spring vegetation growth could also restrain dust storms through accumulating aboveground biomass and increasing surface roughness. To investigate the impacts of vegetation spring growth on dust storms, we examine the relationships between recorded spring dust storm outbreaks and satellite-derived vegetation green-up date in Inner Mongolia, Northern China from 1982 to 2008. We find a significant dampening effect of advanced vegetation growth on spring dust storms (r = 0.49, p = 0.01), with a one-day earlier green-up date corresponding to a decrease in annual spring dust storm outbreaks by 3%. Moreover, the higher correlation (r = 0.55, p < 0.01) between green-up date and dust storm outbreak ratio (the ratio of dust storm outbreaks to times of strong wind events) indicates that such effect is independent of changes in surface wind. Spatially, a negative correlation is detected between areas with advanced green-up dates and regional annual spring dust storms (r = -0.49, p = 0.01). This new insight is valuable for understanding dust storms dynamics under the changing climate. Our findings suggest that dust storms in Inner Mongolia will be further mitigated by the projected earlier vegetation green-up in the warming world. PMID:25343265

  17. Changes toward earlier streamflow timing across western North America

    USGS Publications Warehouse

    Stewart, I.T.; Cayan, D.R.; Dettinger, M.D.

    2005-01-01

    The highly variable timing of streamflow in snowmelt-dominated basins across western North America is an important consequence, and indicator, of climate fluctuations. Changes in the timing of snowmelt-derived streamflow from 1948 to 2002 were investigated in a network of 302 western North America gauges by examining the center of mass for flow, spring pulse onset dates, and seasonal fractional flows through trend and principal component analyses. Statistical analysis of the streamflow timing measures with Pacific climate indicators identified local and key large-scale processes that govern the regionally coherent parts of the changes and their relative importance. Widespread and regionally coherent trends toward earlier onsets of springtime snowmelt and streamflow have taken place across most of western North America, affecting an area that is much larger than previously recognized. These timing changes have resulted in increasing fractions of annual flow occurring earlier in the water year by 1-4 weeks. The immediate (or proximal) forcings for the spatially coherent parts of the year-to-year fluctuations and longer-term trends of streamflow timing have been higher winter and spring temperatures. Although these temperature changes are partly controlled by the decadal-scale Pacific climate mode [Pacific decadal oscillation (PDO)], a separate and significant part of the variance is associated with a springtime warming trend that spans the PDO phases. ?? 2005 American Meteorological Society.

  18. Glacial lake drainage in Patagonia (13-8 kyr) and response of the adjacent Pacific Ocean.

    PubMed

    Glasser, Neil F; Jansson, Krister N; Duller, Geoffrey A T; Singarayer, Joy; Holloway, Max; Harrison, Stephan

    2016-01-01

    Large freshwater lakes formed in North America and Europe during deglaciation following the Last Glacial Maximum. Rapid drainage of these lakes into the Oceans resulted in abrupt perturbations in climate, including the Younger Dryas and 8.2 kyr cooling events. In the mid-latitudes of the Southern Hemisphere major glacial lakes also formed and drained during deglaciation but little is known about the magnitude, organization and timing of these drainage events and their effect on regional climate. We use 16 new single-grain optically stimulated luminescence (OSL) dates to define three stages of rapid glacial lake drainage in the Lago General Carrera/Lago Buenos Aires and Lago Cohrane/Pueyrredón basins of Patagonia and provide the first assessment of the effects of lake drainage on the Pacific Ocean. Lake drainage occurred between 13 and 8 kyr ago and was initially gradual eastward into the Atlantic, then subsequently reorganized westward into the Pacific as new drainage routes opened up during Patagonian Ice Sheet deglaciation. Coupled ocean-atmosphere model experiments using HadCM3 with an imposed freshwater surface "hosing" to simulate glacial lake drainage suggest that a negative salinity anomaly was advected south around Cape Horn, resulting in brief but significant impacts on coastal ocean vertical mixing and regional climate. PMID:26869235

  19. NGRIP temperature reconstruction from 10 to 120 kyr b2k

    NASA Astrophysics Data System (ADS)

    Kindler, P.; Guillevic, M.; Baumgartner, M.; Schwander, J.; Landais, A.; Leuenberger, M.

    2013-07-01

    In order to reconstruct Greenland NGRIP temperature, measurements of δ15N from the beginning of the Holocene to Dansgaard-Oeschger (DO) event 8 have been performed. Together with previously measured and mostly published δ15N data, we are now able to present for the first time a NGRIP temperature reconstruction for the whole last glacial period (beginning of the Holocene back to 120 kyr) including every DO event based on δ15N isotope measurements using a firn densification and heat diffusion model. The detected temperature rises at DO events range from 5 °C (DO 25) up to 16.5 °C (DO 11), ± 3 °C. To bring measured and modelled data into agreement, we had to reduce the accumulation rate given by the ss09sea06bm time scale in some periods significantly, especially during the last glacial maximum (LGM). A comparison between reconstructed temperature and δ18Oice data confirms that the isotopic composition of the stadial was strongly influenced by seasonality. We continuously calculated α (δ18Oice to temperature sensitivity) on a 10 kyr running time window. α variations show an anticorrelation with obliquity, in agreement with a simple Rayleigh distillation model, and moreover seem to be influenced by Northern Hemisphere ice sheet volume.

  20. Variations in the geomagnetic dipole moment during the Holocene and the past 50 kyr

    NASA Astrophysics Data System (ADS)

    Knudsen, Mads Faurschou; Riisager, Peter; Donadini, Fabio; Snowball, Ian; Muscheler, Raimund; Korhonen, Kimmo; Pesonen, Lauri J.

    2008-07-01

    All absolute paleointensity data published in peer-reviewed journals were recently compiled in the GEOMAGIA50 database. Based on the information in GEOMAGIA50, we reconstruct variations in the geomagnetic dipole moment over the past 50 kyr, with a focus on the Holocene period. A running-window approach is used to determine the axial dipole moment that provides the optimal least-squares fit to the paleointensity data, whereas associated error estimates are constrained using a bootstrap procedure. We subsequently compare the reconstruction from this study with previous reconstructions of the geomagnetic dipole moment, including those based on cosmogenic radionuclides ( 10Be and 14C). This comparison generally lends support to the axial dipole moments obtained in this study. Our reconstruction shows that the evolution of the dipole moment was highly dynamic, and the recently observed rates of change (5% per century) do not appear unique. We observe no apparent link between the occurrence of archeomagnetic jerks and changes in the geomagnetic dipole moment, suggesting that archeomagnetic jerks most likely represent drastic changes in the orientation of the geomagnetic dipole axis or periods characterized by large secular variation of the non-dipole field. This study also shows that the Holocene geomagnetic dipole moment was high compared to that of the preceding ˜ 40 kyr, and that ˜ 4 · 10 22 Am 2 appears to represent a critical threshold below which geomagnetic excursions and reversals occur.

  1. 100 Kyr Old Desert of Western India: Morhodynamics and Environmental Significance

    NASA Astrophysics Data System (ADS)

    Bhatt, N.

    2012-04-01

    The Late Quaternary oscillations in sea levels and resultant changes in the coastal environment have remained a popular aspect of study amongst the earthscientists and archaeologists. The Saurashtra peninsula of the western India that lies on the southwestern side of the Thar Desert, has archived a fascinating record of such environmental changes since last interglacial (~120kyr) in the form of a fossil desert exhibiting various aeolian land forms constituted by the sand largely derived from the coastal areas due to an oscillatory sea level change. A variety of dunes viz., coastal transverse, parabolic, longitudinal, barchans, climbing and falling dunes along with valley fills and sand sheets have been mapped. Being biogenic calcium carbonate rich, the sands have been lithified under the influence of an increase in moisture and thus the dune and bed forms are preserved in its best shape. The intense aeolian activities are also evident in the form of desert varnish on rocky outcrops. The sequence comprises smaller climate perturbations in the form of stabilization, erosion and karstification of older dunes and deposition of fluvial sediments in between. The paper deals with the mode of occurrence, response of sediments to wind dynamics and palaeo topography, internal structures, later modifications of sediments and significance of the geochronologically constrained aeolianites in understanding of environmental changes since 100kyr in the region.

  2. Glacial lake drainage in Patagonia (13-8 kyr) and response of the adjacent Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Glasser, Neil F.; Jansson, Krister N.; Duller, Geoffrey A. T.; Singarayer, Joy; Holloway, Max; Harrison, Stephan

    2016-02-01

    Large freshwater lakes formed in North America and Europe during deglaciation following the Last Glacial Maximum. Rapid drainage of these lakes into the Oceans resulted in abrupt perturbations in climate, including the Younger Dryas and 8.2 kyr cooling events. In the mid-latitudes of the Southern Hemisphere major glacial lakes also formed and drained during deglaciation but little is known about the magnitude, organization and timing of these drainage events and their effect on regional climate. We use 16 new single-grain optically stimulated luminescence (OSL) dates to define three stages of rapid glacial lake drainage in the Lago General Carrera/Lago Buenos Aires and Lago Cohrane/Pueyrredón basins of Patagonia and provide the first assessment of the effects of lake drainage on the Pacific Ocean. Lake drainage occurred between 13 and 8 kyr ago and was initially gradual eastward into the Atlantic, then subsequently reorganized westward into the Pacific as new drainage routes opened up during Patagonian Ice Sheet deglaciation. Coupled ocean-atmosphere model experiments using HadCM3 with an imposed freshwater surface “hosing” to simulate glacial lake drainage suggest that a negative salinity anomaly was advected south around Cape Horn, resulting in brief but significant impacts on coastal ocean vertical mixing and regional climate.

  3. Glacial lake drainage in Patagonia (13-8 kyr) and response of the adjacent Pacific Ocean

    PubMed Central

    Glasser, Neil F.; Jansson, Krister N.; Duller, Geoffrey A. T.; Singarayer, Joy; Holloway, Max; Harrison, Stephan

    2016-01-01

    Large freshwater lakes formed in North America and Europe during deglaciation following the Last Glacial Maximum. Rapid drainage of these lakes into the Oceans resulted in abrupt perturbations in climate, including the Younger Dryas and 8.2 kyr cooling events. In the mid-latitudes of the Southern Hemisphere major glacial lakes also formed and drained during deglaciation but little is known about the magnitude, organization and timing of these drainage events and their effect on regional climate. We use 16 new single-grain optically stimulated luminescence (OSL) dates to define three stages of rapid glacial lake drainage in the Lago General Carrera/Lago Buenos Aires and Lago Cohrane/Pueyrredón basins of Patagonia and provide the first assessment of the effects of lake drainage on the Pacific Ocean. Lake drainage occurred between 13 and 8 kyr ago and was initially gradual eastward into the Atlantic, then subsequently reorganized westward into the Pacific as new drainage routes opened up during Patagonian Ice Sheet deglaciation. Coupled ocean-atmosphere model experiments using HadCM3 with an imposed freshwater surface “hosing” to simulate glacial lake drainage suggest that a negative salinity anomaly was advected south around Cape Horn, resulting in brief but significant impacts on coastal ocean vertical mixing and regional climate. PMID:26869235

  4. Toward a continuous 405-kyr-calibrated Astronomical Time Scale for the Mesozoic Era

    NASA Astrophysics Data System (ADS)

    Hinnov, Linda; Ogg, James; Huang, Chunju

    2010-05-01

    Mesozoic cyclostratigraphy is being assembled into a continuous Astronomical Time Scale (ATS) tied to the Earth's cyclic orbital parameters. Recognition of a nearly ubiquitous, dominant ~400-kyr cycling in formations throughout the era has been particularly striking. Composite formations spanning contiguous intervals up to 50 myr clearly express these long-eccentricity cycles, and in some cases, this cycling is defined by third- or fourth-order sea-level sequences. This frequency is associated with the 405-kyr orbital eccentricity cycle, which provides a basic metronome and enables the extension of the well-defined Cenozoic ATS to scale the majority of the Mesozoic Era. This astronomical calibration has a resolution comparable to the 1% to 0.1% precision for radioisotope dating of Mesozoic ash beds, but with the added benefit of providing continuous stratigraphic coverage between dated beds. Extended portions of the Mesozoic ATS provide solutions to long-standing geologic problems of tectonics, eustasy, paleoclimate change, and rates of seafloor spreading.

  5. Trend of earlier spring in central Europe continued

    NASA Astrophysics Data System (ADS)

    Ungersböck, Markus; Jurkovic, Anita; Koch, Elisabeth; Lipa, Wolfgang; Scheifinger, Helfried; Zach-Hermann, Susanne

    2013-04-01

    Modern phenology is the study of the timing of recurring biological events in the animal and plant world, the causes of their timing with regard to biotic and abiotic forces, and the interrelation among phases of the same or different species. The relationship between phenology and climate explains the importance of plant phenology for Climate Change studies. Plants require light, water, oxygen mineral nutrients and suitable temperature to grow. In temperate zones the seasonal life cycle of plants is primarily controlled by temperature and day length. Higher spring air temperatures are resulting in an earlier onset of the phenological spring in temperate and cool climate. On the other hand changes in phenology due to climate change do have impact on the climate system itself. Vegetation is a dynamic factor in the earth - climate system and has positive and negative feedback mechanisms to the biogeochemical and biogeophysical fluxes to the atmosphere Since the mid of the 1980s spring springs earlier in Europe and autumn is shifting back to the end of the year resulting in a longer vegetation period. The advancement of spring can be clearly attributed to temperature increase in the months prior to leaf unfolding and flowering, the timing of autumn is more complex and cannot easily be attributed to one or some few parameters. To demonstrate that the observed advancement of spring since the mid of 1980s is pro-longed in 2001 to 2010 and the delay of fall and the lengthening of the growing season is confirmed in the last decade we picked out several indicator plants from the PEP725 database www.pep725.eu. The PEP725 database collects data from different European network operators and thus offers a unique compilation of phenological observations; the database is regularly updated. The data follow the same classification scheme, the so called BBCH coding system so they can be compared. Lilac Syringa vulgaris, birch Betula pendula, beech Fagus and horse chestnut Aesculus

  6. Reducing older driver motor vehicle collisions via earlier cataract surgery.

    PubMed

    Mennemeyer, Stephen T; Owsley, Cynthia; McGwin, Gerald

    2013-12-01

    Older adults who undergo cataract extraction have roughly half the rate of motor vehicle collision (MVC) involvement per mile driven compared to cataract patients who do not elect cataract surgery. Currently in the U.S., most insurers do not allow payment for cataract surgery based upon the findings of a vision exam unless accompanied by an individual's complaint of visual difficulties that seriously interfere with driving or other daily activities and individuals themselves may be slow or reluctant to complain and seek relief. As a consequence, surgery tends to occur after significant vision problems have emerged. We hypothesize that a proactive policy encouraging cataract surgery earlier for a lesser level of complaint would significantly reduce MVCs among older drivers. We used a Monte Carlo model to simulate the MVC experience of the U.S. population from age 60 to 89 under alternative protocols for the timing of cataract surgery which we call "Current Practice" (CP) and "Earlier Surgery" (ES). Our base model finds, from a societal perspective with undiscounted 2010 dollars, that switching to ES from CP reduces by about 21% the average number of MVCs, fatalities, and MVC cost per person. The net effect on total cost - all MVC costs plus cataract surgery expenditures - is a reduction of about 16%. Quality Adjusted Life Years would increase by about 5%. From the perspective of payers for healthcare, the switch would increase cataract surgery expenditure for ages 65+ by about 8% and for ages 60-64 by about 47% but these expenditures are substantially offset after age 65 by reductions in the medical and emergency services component of MVC cost. Similar results occur with discounting at 3% and with various sensitivity analyses. We conclude that a policy of ES would significantly reduce MVCs and their associated consequences. PMID:23369786

  7. Abrupt Climatic Events Observed in Organic-Rich Sediments From Lake Tanganyika, Tropical East Africa, Over the Past 50 kyr

    NASA Astrophysics Data System (ADS)

    Burnett, A. P.; Weyhenmeyer, C. E.; Scholz, C. A.; Swart, P. K.

    2006-12-01

    Abrupt climate changes such as Dansgaard-Oeschger Cycles and Heinrich Events were first detected in high- latitude records, but an increasing number of studies suggest that these rapid changes are actually global events. The degree to which the tropics drive, control and/or respond to such rapid changes is still poorly understood due to a scarcity of data from low-latitude regions. A recently acquired sediment core from Lake Tanganyika, East Africa, provides a unique archive to study abrupt climate events in the tropics throughout the last glaciation. The core provides a continuous, undisturbed and high resolution climate record over the past 100 kyr. An age-depth model based on 25 new radiocarbon dates provides a solid, high-resolution chronology for the past 50 kyr. Throughout this time, several rapid changes in paleoclimate proxy data are observed along the core. Sedimentation rates remained fairly constant from the Holocene until the Last Glacial Maximum (LGM) but increased abruptly from ~80 mm/1000 yr to ~150 mm/1000 yr around 18 kyr BP. At the same time, the sediment record reveals a sudden increase in total organic carbon (TOC) from 4% to 12% indicating a rapid increase in organic matter contributions at the end of the LGM. Abrupt changes in TOC and δ13C values are also found at ~38 kyr, ~30 kyr and ~16 kyr BP, suggesting a possible link to Heinrich events 4, 3 and 1, respectively. Forthcoming very high-resolution analyses, to augment existing low-resolution data, include δ13C, δ15N, C/N ratios and TOC values. Furthermore, TEX86 measurements will be carried out to determine whether the observed changes in organic matter contributions are associated with changes in water temperatures. In combination with the solid 14C chronology, the new data will allow us to precisely determine the onset, timing and nature of abrupt changes and evaluate them in the global context.

  8. Scar revision

    MedlinePlus

    ... prevention, treatment, and revision. In: Neligan PC, ed. Plastic Surgery . 3rd ed. Philadelphia, PA: Elsevier; 2013:chap ... Hebe Molmenti, MD, PhD, private practice specializing in plastic and reconstructive surgery, Baltimore, MD. Review provided by ...

  9. Changes in chemical weathering intensity in the Himalayas over the past 30 kyr

    NASA Astrophysics Data System (ADS)

    Dosseto, A.; Vigier, N.

    2010-12-01

    Chemical weathering and climate are tightly coupled and in an era of rapid climate change, it is critical to be able to understand how erosion processes respond to climate variability. A possible approach is to investigate sedimentary records and study how in the past, sediments have recorded the response of catchment erosion to climate variability. In this study, we have measured lithium (Li) isotopes in sediments deposited on river terraces in the upper Ganges (Alaknanda) and Yamuna basins (India) with deposition ages ranging from 0 to 26 kyr. Li isotopes fractionate during chemical weathering and could potentially give us some insights on past variations of weathering intensity. We find that Li isotope composition vary between -1.5 and 2 ‰. Before 14 kyr ago, sediments exhibit negative values followed a sharp increase to positive values between 11 and 14 kyr ago. This increase in could be explained by (i) an increase in average temperature, where a higher temperature of equilibration between water and precipitating clays results in higher Li isotope ratios; (ii) a change in mineralogy, as the type and crystallinity of clays will fact the isotopic composition; or (iii) a decrease in chemical weathering intensity, as Li isotope ratios are believed to decrease in sediments/soils with increasing weathering intensity (Rudnick et al., 2004). Interestingly, this period of shift in Li isotope composition also corresponds to an intensification of monsoon rainfall. If the change in Li isotope compositions is the result of a decrease of chemical weathering intensity, this would imply that despite of more intense rainfall, weathering has been less intense during the Holocene. This could be explained as greater rainfall will generate more erosion and sediments are likely to spend less time in the basin, thus the amount of time available for weathering is reduced. This would imply that chemical weathering is mostly controlled by the erosive power of greater rainfall over

  10. Poorest countries experience earlier anthropogenic emergence of daily temperature extremes

    NASA Astrophysics Data System (ADS)

    Harrington, Luke J.; Frame, David J.; Fischer, Erich M.; Hawkins, Ed; Joshi, Manoj; Jones, Chris D.

    2016-05-01

    Understanding how the emergence of the anthropogenic warming signal from the noise of internal variability translates to changes in extreme event occurrence is of crucial societal importance. By utilising simulations of cumulative carbon dioxide (CO2) emissions and temperature changes from eleven earth system models, we demonstrate that the inherently lower internal variability found at tropical latitudes results in large increases in the frequency of extreme daily temperatures (exceedances of the 99.9th percentile derived from pre-industrial climate simulations) occurring much earlier than for mid-to-high latitude regions. Most of the world’s poorest people live at low latitudes, when considering 2010 GDP-PPP per capita; conversely the wealthiest population quintile disproportionately inhabit more variable mid-latitude climates. Consequently, the fraction of the global population in the lowest socio-economic quintile is exposed to substantially more frequent daily temperature extremes after much lower increases in both mean global warming and cumulative CO2 emissions.

  11. Earlier North American Monsoon Onset in a Warmer World?

    NASA Astrophysics Data System (ADS)

    Rauscher, S. A.; Seth, A.; Ringler, T.; Rojas, M.; Liebmann, B.

    2009-12-01

    Analysis of twenty-first century projections indicate substantial drying over the American Southwest and the potential for “Dust Bowl” conditions to be the norm by the middle of century. Closer examination of monthly precipitation data from the CMIP3 models indicates that the annual cycle is actually amplified over the North American Monsoon (NAMS) region, with drier conditions during the winter and an increase in monsoon rains during the later part of the rainy season. Importantly, the projected decrease in winter precipitation extends into the spring season, suggesting a delayed onset of the NAMS. Consistent thermodynamic changes, including a decrease in low-level relative humidity and an increase in the vertical gradient of moist static energy, accompany this spring precipitation decrease. Here we examine daily precipitation data from the CMIP3 archive to determine if this reduced spring precipitation represents a true delay in the NAMS onset. We further analyze the hydrological cycle over the NAMS region in several of the CMIP3 models, focusing on changes in net moisture divergence, surface evaporation, and soil moisture in order to fully understand how the hydrological cycle will change in the future based on the CMIP3 simulations, and how these changes may be translated into the timing and intensity of the NAMS. The combination of a delayed NAMS onset and earlier and reduced snowmelt runoff in the western US could substantially change the availability of water resources over the NAMS region.

  12. Geomagnetic intensity variations for the past 8 kyr: New archaeointensity results from Eastern China

    NASA Astrophysics Data System (ADS)

    Cai, Shuhui; Tauxe, Lisa; Deng, Chenglong; Pan, Yongxin; Jin, Guiyun; Zheng, Jianming; Xie, Fei; Qin, Huafeng; Zhu, Rixiang

    2014-04-01

    In this study, we have carried out paleointensity experiments on 918 specimens spanning the last ∼7 kyr, including pottery fragments, baked clay and slag, collected from Shandong, Liaoning, Zhejiang and Hebei Provinces in China. Approximately half of the specimens yielded results that passed strict data selection criteria and give high-fidelity paleointensities. The virtual axial dipole moments (VADMs) of our sites range from ∼2×1022 to ∼13×1022 Am. At ∼2250 BCE our results suggest a paleointensity low of ∼2×1022 Am, which increases to a high of ∼13×1022 Am by ∼1300 BCE. This rapid (less than 1000 yrs) six-fold change in the paleointensity may have important implications for the dynamics of core flow at this time. Our data from the last ∼3 kyr are generally in good agreement with the ARCH3k.1 model, but deviate significantly at certain time periods from the CALS3k.4 and CALS10k.1b model, which is likely due to differences in the data used to constrain these models. At ages older than ∼3 ka, where only the CALS10k.1b model is available for comparison, our data deviate significantly from the model. Combining our new results with the published data from China and Japan, we provide greatly improved constraints for the regional model of Eastern Asia. When comparing the variations of geomagnetic field in three global representative areas of Eastern Asia, the Middle East and Southern Europe, a common general trend of sinusoidal variations since ∼8 ka is shown, likely dominated by the dipole component. However, significant disparities are revealed as well, which we attribute to non-dipolar components caused by movement of magnetic flux patches at the core-mantle boundary.

  13. Geomagnetic intensity variations for the past 6 kyr: New archeointensity results from China

    NASA Astrophysics Data System (ADS)

    Cai, S.; Tauxe, L.; Deng, C.; Zhu, R.

    2013-05-01

    The geomagnetic field is a window to the motion of the fluid outer core of Earth, which has varied over a broad range of timescales. To understand this variation over periods of thousands of years we rely entirely on measurements of remanent magnetization from geological and archeological materials. Archeomagnetic data from Eastern Asia, however, are sparse, particularly those that would be widely regarded as reliable. The longevity of Chinese civilization and the abundant nature of archeological artifacts make archeomagnetic studies within China an important tool for filling in many gaps in our current data sets. In this study, have we carried out paleointensity experiments on 969 specimens, which includes pottery fragments, burnt earth and slags, collected from Shandong, Zhejiang and Hebei Province in China and span the last 6 kyr. Approximately half of the samples yielded results that passed strict data selection and give high-fidelity paleointensities. The virtual axial dipoles moments (VADMs) of our sites range from 4 to 12e22Am2. Our data from the last 2.5 kyr are in good agreement with the ARCH3k.1 model, but deviate at times from the CALS10k.1b model, which is likely due to differences in the data used for these models. At ages older than 3ka, where only the CALS10k.1b model is available for comparison, our data deviate significantly from the model. At ca. 1350 BCE our results suggest a paleointensity high of 12E22Am2, which drops to a low of 4E22Am2 by 2250 BCE. This rapid (less than 1000 year) three-fold change in the paleointensity may have important implications for the dynamics of core flow at this time.

  14. Intercomparison of Simulated Global Vegetation Distributions in Response to 6 kyr BP Orbital Forcing.

    NASA Astrophysics Data System (ADS)

    Harrison, S. P.; Jolly, D.; Laarif, F.; Abe-Ouchi, A.; Dong, B.; Herterich, K.; Hewitt, C.; Joussaume, S.; Kutzbach, J. E.; Mitchell, J.; de Noblet, N.; Valdes, P.

    1998-11-01

    The response of ten atmospheric general circulation models to orbital forcing at 6 kyr BP has been investigated using the BIOME model, which predicts equilibrium vegetation distribution, as a diagnostic. Several common features emerge: (a) reduced tropical rain forest as a consequence of increased aridity in the equatorial zone, (b) expansion of moisture-demanding vegetation in the Old World subtropics as a consequence of the expansion of the Afro-Asian monsoon, (c) an increase in warm grass/shrub in the Northern Hemisphere continental interiors in response to warming and enhanced aridity, and (d) a northward shift in the tundra-forest boundary in response to a warmer growing season at high northern latitudes. These broadscale features are consistent from model to model, but there are differences in their expression at a regional scale. Vegetation changes associated with monsoon enhancement and high-latitude summer warming are consistent with palaeoenvironmental observations, but the simulated shifts in vegetation belts are too small in both cases. Vegetation changes due to warmer and more arid conditions in the midcontinents of the Northern Hemisphere are consistent with palaeoenvironmental data from North America, but data from Eurasia suggests conditions were wetter at 6 kyr BP than today. The models show quantitatively similar vegetation changes in the intertropical zone, and in the northern and southern extratropics. The small differences among models in the magnitude of the global vegetation response are not related to differences in global or zonal climate averages, but reflect differences in simulated regional features. Regional-scale analyses will therefore be necessary to identify the underlying causes of such differences among models.

  15. Geomagnetic field variations during the last 400 kyr in the western equatorial Pacific: Paleointensity-inclination correlation revisited

    NASA Astrophysics Data System (ADS)

    Yamazaki, Toshitsugu; Kanamatsu, Toshiya; Mizuno, Sakiko; Hokanishi, Natsumi; Gaffar, Eddy Z.

    2008-10-01

    A paleomagnetic study was conducted on four piston cores newly obtained from the West Caroline Basin in the western equatorial Pacific in order to investigate variations in paleointensity and inclination during the last 400 kyr. An inclination-intensity correlation was previously reported in this region using giant piston cores, but the quality of the paleomagnetic data of the younger end, the last ca. 300 kyr, was needed to be checked because the upper part of the giant piston cores could suffer from perturbation by oversampling. Age control is based on the oxygen-isotope ratios for one core and inter-core correlation using relative paleointensity for other cores. Stacked curves of paleointensity and inclination were constructed from the four cores. It was confirmed that variations on the order of 104 to 105 years occur in inclination as well as paleointensity. A cross-correlation analysis showed that significant in-phase correlation occurs between intensity and inclination for periods longer than about 25 kyr, and power spectra of both paleointensity and inclination variations have peaks at ~100 kyr periods. The regional paleointensity stack with higher resolution than the Sint-800 stack (Guyodo and Valet, 1999) should be useful for paleointensity-assisted chronostratigraphy.

  16. Geomagnetic field variations during the last 400 kyr in the western equatorial Pacific: Paleointensity-inclination correlation revisited

    NASA Astrophysics Data System (ADS)

    Yamazaki, T.; Kanamatsu, T.; Mizuno, S.; Hokanishi, N.; Gaffar, E. Z.

    2008-12-01

    A paleomagnetic study was conducted on four piston cores newly obtained from the West Caroline Basin in the western equatorial Pacific in order to investigate variations in paleointensity and inclination during the last 400 kyr. An inclination-intensity correlation was previously reported in this region using giant piston cores, but the quality of the paleomagnetic data of the younger end, the last ca. 300 kyr, was needed to be checked because the upper part of the giant piston cores could suffer from perturbation by oversampling. Age control is based on the oxygen-isotope ratios for one core and inter-core correlation using relative paleointensity for other cores. The mean inclinations of the four cores show negative inclination anomalies ranging from -5.2 to -11.2 degree. The western equatorial Pacific is documented as a region of a large negative inclination anomalies, and the observed values are comparable to those expected from the time-averaged field (TAF) models [Johnson and Constable, 1997; Hatakeyama and Kono, 2002]. Stacked curves of paleointensity and inclination were constructed from the four cores. It was confirmed that geomagnetic variations on the order of 10 to 100 kyrs occur in inclination as well as paleointensity. A cross-correlation analysis showed that significant in-phase correlation occurs between intensity and inclination for periods longer than about 25 kyr, and power spectra of both paleointensity and inclination variations have peaks at ~100 kyr periods. The regional paleointensity stack with higher resolution than the Sint-800 stack [Guyodo and Valet, 1999] should be useful for paleointensity-assisted chronostratigraphy.

  17. Revision Rhinoplasty.

    PubMed

    Loyo, Myriam; Wang, Tom D

    2016-01-01

    Revision rhinoplasty is one of the most challenging operations the facial plastic surgeon performs given the complex 3-dimensional anatomy of the nose and the psychological impact it has on patients. The intricate interplay of cartilages, bone, and soft tissue in the nose gives it its aesthetic and function. Facial harmony and attractiveness depends greatly on the nose given its central position in the face. In the following article, the authors review common motivations and anatomic findings for patients seeking revision rhinoplasty based on the senior author's 30-year experience with rhinoplasty and a review of the literature. PMID:26616705

  18. Progress in the reconstruction of Quaternary climate dynamics in the Northwest Pacific: A new modern analogue reference dataset and its application to the 430-kyr pollen record from Lake Biwa

    NASA Astrophysics Data System (ADS)

    Tarasov, Pavel E.; Nakagawa, Takeshi; Demske, Dieter; Österle, Hermann; Igarashi, Yaeko; Kitagawa, Junko; Mokhova, Lyudmila; Bazarova, Valentina; Okuda, Masaaki; Gotanda, Katsuya; Miyoshi, Norio; Fujiki, Toshiyuki; Takemura, Keiji; Yonenobu, Hitoshi; Fleck, Andreas

    2011-09-01

    This study presents a newly compiled dataset of modern pollen and climate data from 798 sites across Japan and the Russian Far East. This comprehensive reference dataset combined with the modern analogue technique (MAT) provides a powerful tool for pollen-based reconstruction of the Quaternary Northwest Pacific climate. Pollen-derived reconstruction of the modern climate at the reference pollen-sampling sites matches well with the estimated modern climate values ( R2 values vary between 0.79 and 0.95, and RMSEP values vary between 5.8 and 9.7% of the modern climatic range for all nine tested variables). The successful testing of the method encourages its application to the fossil pollen records. We used a coarse-resolution pollen record from Lake Biwa to reconstruct glacial-interglacial climate dynamics in central Japan since ~ 438 kyr and compared it to the earlier reconstruction based on a less representative reference dataset. The current and earlier results consistently demonstrate that the coldest glacial intervals experienced pronounced cooling in winter and moderate cooling in summer, supporting the growth of cool mixed forest (COMX) where warm mixed forest (WAMX) predominates today. During the last glacial, maximum (~ 24 kyr BP) mean temperatures of the coldest (MTCO) and warmest (MTWA) month were about - 13 °C (RMSEP = 2.34 °C) and 21 °C (RMSEP = 1.66 °C) respectively, and annual precipitation (PANN) was about 800 mm (RMSEP = 158.06 mm). During the thermal optimums of the interglacial intervals, the temperatures of the coldest and warmest month were above 0 °C and 25 °C respectively, leading to the reconstruction of WAMX and temperate conifer forest (TECO). Although both these vegetation types grow in the southern part of Japan today, WAMX requires warmer space. The presence of WAMX during marine isotope stages (MIS) 11 and 1, and its absence during MIS 9 and MIS 5 contradict the marine isotope and Antarctic ice records, suggesting that the latter

  19. Circum-Antarctic Nd isotope variability during the last 30 kyrs

    NASA Astrophysics Data System (ADS)

    Struve, T.; van de Flierdt, T.; Hines, S. K.; Burke, A.; Adkins, J. F.; Robinson, L. F.; Crocket, K. C.; Auro, M. E.

    2014-12-01

    The modern Southern Ocean is a key area for the global ocean circulation as wind-driven mixing, upwelling and redistribution of water masses in the Antarctic Circumpolar Current (ACC) all have a significant impact on the properties and flow patterns of global water masses. It has been suggested that the Southern Ocean plays a critical role in oceanographic and climatic changes observed on glacial-interglacial timescales, in particular with respect to carbon sequestration between the deep ocean and the atmosphere. For the purpose of unravelling Southern Ocean water mass composition at intermediate depth during the past 30 kyrs, we here utilise the Nd isotopic composition of the aragonitic skeletons of solitary deep-sea corals. These corals were collected from two locations, the Drake Passage and the area south of Tasmania, and from water depths between 300 and 1750 m. Modern coral specimen were calibrated against nearby seawater. Neodymium was collected from the wash fraction of the anion-exchange column, which represents the first step in preparing samples for precise U-series dating. Subsequent Nd separation utilised a two-stage ion chromatography (RE-spec/cation exchange and Ln-spec resins). Isotopic analyses were performed as NdO+ on a Triton TIMS using a TaF5 activator on W filaments yielding 2σ external reproducibilities of ~20 ppm. (Sub-) millenial scale deep-sea coral neodymium isotope results from the Drake Passage suggest that the modern homogenous ACC neodymium isotopic composition of ɛNd≈ -8 is a very recent feature. During the past 30 kyrs Nd isotope variability on the order of two epsilon units are observed at intermediate water depths as well as repeated changes in water column stratification. We will discuss our new results in the context of other Southern Ocean records, as well as preliminary Nd isotope data from glacial to deglacial deep-sea corals from south of Tasmania in order to constrain the last glacial to deglacial circum-Antarctic Nd

  20. Biogenic sedimentation beneath the California Current system for the past 30 kyr and its paleoceanographic significance

    USGS Publications Warehouse

    Gardner, J.V.; Dean, W.E.; Dartnell, P.

    1997-01-01

    A north-south transect of 17 cores was constructed along the eastern boundary of the California Current system from 33?? to 42?? N to investigate the changes in biogenic sedimentation over the past 30 kyr. Percentages and mass accumulation rates of CaCO3, Corg, and biogenic opal were assembled at 500 to 1000 years/sample to provide relatively high resolution. Time-space maps reveal a complex pattern of changes that do not follow a simple glacial-interglacial two-mode model. Biogenic sedimentation shows responses that are sometimes time-transgressive and sometimes coeval, and most of the responses show more consistency within a limited geographic area than any temporal consistency. Reconstructed conditions during late oxygen isotope stage 3 were more like early Holocene conditions than any other time during the last 30 kyr. Coastal upwelling and productivity during oxygen isotope stage 3 were relatively strong along the central California margin but were weak along the northern California margin. Precipitation increased during the last glacial interval in the central California region, and the waters of the southern California margin had relatively low productivity. Productivity on the southern Oregon margin was relatively low at the beginning of the last glacial interval, but by about 20 ka, productivity in this area significantly increased. This change suggests that the center of the divergence of the West Wind Drift shifted south at this time. The end of the last glacial interval was characterized by increased productivity in the southern California margin and increased upwelling along the central California margin but upwelling remained weak along the northern California margin. A sudden (<300 years) decrease in CaCO3, Corg, and biogenic opal occurred at 13 ka. The changes suggest a major reorientation of the atmospheric circulation in the North Pacific and western North America and the establishment of a strong seasonality in the central California region. A

  1. Scenario Of The 4 kyr Extraterrestrial Impact : Crater Location, Ejecta-Dispersion and Consequences.

    NASA Astrophysics Data System (ADS)

    Courty, M.; Abbott, D. H.; Cortese, G.; Crisci, A.; Crosta, X.; de Wever, P.; Fedoroff, M.; Greenwood, P.; Grice, K.; Mermoux, M.; Scharer, U.; Smith, D. C.; Thiemens, M. H.

    2006-12-01

    The 4 kyr BP impact event has been identified from deep-sea, soil and archaeological records as the worldwide pulverisation of a volatile-rich debris jet(1). High resolution sequences show two stages of ejecta fallout linked to the impact-triggered doublet gaseous regime(2): scattered solid debris at the ground surface and spray of the vaporized hot fireball with thermal blast and local ignition. Ejecta debris consist of flow- textured impact glass, impact breccia and incompletely melted marine clasts: volcano-clastic sandy mudstone, calcareous mud, granite-gneiss, schists, volcanic breccia, kerogen and algal mud. Marine microfossils, organo-mineral markers, and the debris-fallout spatial pattern indicate two potential impact craters: an Antarctic source with an admixture of volcanic glass and ice rafted debris, from the vicinity of Heard Island and the Kerguelen plateau; a low latitude, shallow water one with hydrocarbons possibly from the Gulf of Mexico. Fine mixing of target materials from far distant source craters emphasizes a unique impact-ejecta. This matches the theoretical view of a debris jet channelled along the corridor cut through the atmosphere by the incoming projectile, raised upward, and dispersed widely(3). The isotopic anomaly of the sulphur phase in the kerogen volatile-component, indicating mass independent fractionation due to photolytic transformation, suggests launching at great heights, beyond the O2-O3 UV shield, responsible for climate disturbances. The incomplete melting of target rocks and global dispersion of impact breccia out of the craters would result from splash of small-sized projectile at rather great water depth and a low angle impact (10-15 degrees) into porous, highly compressible marine sediments. The spatially variable distribution of the organo-mineral and melt components, and the wide range of phase transformation reflect nonequilibrium shock-melting and micro-scale thermal processes in the heterogeneous vapor plume

  2. Latitudinal Hydrologic Variability Along the East African Rift, Over the Past 200 Kyr

    NASA Astrophysics Data System (ADS)

    Scholz, C. A.

    2014-12-01

    Within the deep sediments of the large lakes of Africa's Great Rift Valley are continuous environmental records of remarkable antiquity and fidelity. Not only do stratigraphic sections from these basins extend back millions of years, many of the intervals represented contain high-resolution material of decadal resolution or better. East African lake basins remain sparsely sampled however, with only a few long and continuous records available. Our ability to image the lakes using seismic reflection methods greatly exceeds our opportunities for coring and drilling however; assessing stratal relationships observed in the geophysical data permits powerful inferences about past hydrologic changes. With intensive hydrocarbon exploration work underway in East Africa, industry well data can also help constrain and ground truth basin histories. Substantial spatio-temporal hydrologic variability is observed in East African basins over the past 200 kyr. Paleohydrological changes in the late Pleistocene and early Holocene are now well constrained in the northern hemisphere East African topics, with widespread aridity and in some cases lake desiccation observed during Heinrich Event 1. A climate recovery followed in the northern hemisphere East African tropics, with the early Holocene African Humid Period a time of positive water balance across most of the rift valley. The paleohydrology of southern hemisphere tropical East Africa is more equivocal, for instance with negligible draw-down of Lake Malawi at HE1. Whereas these late Pleistocene events represent substantial climate reorganizations, severe droughts during the middle-late Pleistocene (150-65 kyr BP) were far more intense, and produced much more severe drawdowns of Lakes Malawi and Tanganyika. Scientific drill cores, kullenberg cores, and extensive seismic reflection data sets from Lakes Malawi and Tanganyika provide indisputable evidence for lowstands of -500m and -600 m respectively. Climate changes that lowered the

  3. Sediment provenance and paleoenvironmental change in the Ulleung Basin of the East (Japan) Sea during the last 21 kyr

    NASA Astrophysics Data System (ADS)

    Xu, Zhaokai; Lim, Dhongil; Choi, Jinyong; Li, Tiegang; Wan, Shiming; Rho, Kyoungchan

    2014-10-01

    Despite the well-reconstructed paleoceanography of the late Quaternary deposits in the East (Japan) Sea (ES), provenances of terrigenous sediments and a comprehensive interpretation of their variations since the Last Glacial Maximum remain unclear, especially in regard to the mainland China- and Taiwan-derived matter. Grain size, conservative trace elements, rare earth elements (REEs), Nd isotope, and clay mineralogy of core sediments from the Ulleung Basin of the ES were investigated for better understanding of detrital sediment provenance and transport process and then their forcing mechanisms over the last 21 kyr. Geochemical-mineralogical multi-indices in this study showed notable three-phase changes in sediment provenance, which can be closely related to sea-level fluctuation, development of the Tsushima Warm Current as well as intermittent influence from the East Asian summer monsoon climate evolution. During Unit 1 (21.1-8.4 kyr BP) when the Tsushima Warm Current was absent in the ES, the paleo-Changjiang and the paleo-Huanghe mouth might be situated close to the study area and thus mainland China could have played major role in the southwestern Ulleung Basin sedimentation. In particular, the formation of rhythmic dark-colored alternation in Unit 1 is possibly attributable to the pulse of paleo-Huanghe discharge associated with centurial- to millennial-scale variability in the East Asian summer monsoon. In Unit 2 (8.4-7.2 kyr BP), these river mouths gradually retreated to their present positions with global sea-level rise, leading to decreasing terrigenous sediment supply from mainland China to the study area. Since 7.2 kyr BP (Unit 3), sedimentation in the Ulleung Basin should still be mainly derived from mainland China. Meanwhile, increasing chlorite/kaolinite ratio but decreasing εNd value revealed that terrigenous matter from Taiwan might have been limitedly transported northward to the study area by the fully evolved Tsushima Warm Current. A prominent

  4. Palaeoecology of a 3-kyr biosedimentary record of a coral reef-supporting carbonate shelf

    NASA Astrophysics Data System (ADS)

    Almeida, Carine M.; Barbosa, Catia Fernandes; Cordeiro, Renato C.; Seoane, José Carlos S.; Fermino, Gerson M.; Silva, Patricia O.; Turcq, Bruno J.

    2013-11-01

    This study assesses the 3-kyr paleoecology and sedimentary evolution of the Abrolhos carbonate shelf, Bahia, Brazil, using a two-meter-long core collected in a carbonate muddy sediment. The paleoecology was based on the distribution of benthic foraminifer functional groups associated with grain size, total organic carbon (TOC), total nitrogen (TN), C/N and δ13C. The results identified three biosedimentary units showing that symbiont-bearing foraminifers (Peneroplis and Archaias) decrease in abundance. However, other small taxa (Miliolinella and Cornuspira) and stress-tolerant genera (Bolivina, Elphidium and Ammonia) increase in abundance toward the core top. Grain size decreases toward the top of the core, suggesting a weakening of hydrodynamic winnowing toward recent time. The TOC and TN concentrations increase, and the C/N ratios decrease, suggesting an increase of marine productivity from nearby goblet-shaped structures called "chapeirões". Changes in the benthic foraminifer community can be linked to the sedimentological and organic matter input, which are the result of climatic and oceanographic variations at different spatial and time scales, thus illustrating reduced potential to support symbiont-bearing foraminifer communities to the end of the Holocene.

  5. Temperature reconstruction from 10 to 120 kyr b2k from the NGRIP ice core

    NASA Astrophysics Data System (ADS)

    Kindler, P.; Guillevic, M.; Baumgartner, M.; Schwander, J.; Landais, A.; Leuenberger, M.; Spahni, R.; Capron, E.; Chappellaz, J.

    2014-04-01

    In order to reconstruct the temperature of the North Greenland Ice Core Project (NGRIP) site, new measurements of δ15N have been performed covering the time period from the beginning of the Holocene to Dansgaard-Oeschger (DO) event 8. Together with previously measured and mostly published δ15N data, we present for the first time a NGRIP temperature reconstruction for the whole last glacial period from 10 to 120 kyr b2k (thousand years before 2000 AD) including every DO event based on δ15N isotope measurements combined with a firn densification and heat diffusion model. The detected temperature rises at the onset of DO events range from 5 °C (DO 25) up to 16.5 °C (DO 11) with an uncertainty of ±3 °C. To bring measured and modelled data into agreement, we had to reduce the accumulation rate given by the NGRIP ss09sea06bm timescale in some periods by 30 to 35%, especially during the last glacial maximum. A comparison between reconstructed temperature and δ18Oice data confirms that the isotopic composition of the stadial was strongly influenced by seasonality. We evidence an anticorrelation between the variations of the δ18Oice sensitivity to temperature (referred to as α) and obliquity in agreement with a simple Rayleigh distillation model. Finally, we suggest that α might be influenced by the Northern Hemisphere ice sheet volume.

  6. Distributive Education: Secondary, Course Outline. Revised 1972.

    ERIC Educational Resources Information Center

    Washington State Coordinating Council for Occupational Education, Olympia.

    The document is a revision of earlier units, updated to include behavioral or performance objectives. Divided into 22 units of instruction, the course outline for distributive education presents suggested length of time for each part of a unit, prerequisites, a description of the part, objectives, sources, outline for the section, activities,…

  7. 78 FR 6736 - Revisions to the California State Implementation Plan, Placer County Air Pollution Control District

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-31

    ... AGENCY 40 CFR Part 52 Revisions to the California State Implementation Plan, Placer County Air Pollution... taking direct final action to approve revisions to the Placer County Air Pollution Control District... earlier version of Rule 102 into the SIP on June 29, 1999 (64 FR 34558). PCAPCD adopted revisions to...

  8. Time evolution of the mineralogical composition of Mississippi Valley loess over the last 10 kyr: Climate and geochemical modeling

    NASA Astrophysics Data System (ADS)

    Goddéris, Yves; Williams, Jennifer Z.; Schott, Jacques; Pollard, Dave; Brantley, Susan L.

    2010-11-01

    Anthropogenic and natural climate change affect processes in the atmosphere, biosphere, hydrosphere, and pedosphere. The impact of climate on soil evolution has not been well-explored, largely due to slow rates and the complexity of coupled processes that must be observed and simulated. The rates of mineral weathering in loess deposited 23 kyr ago and experiencing soil formation for 13 kyr are explored here using the WITCH model for weathering and the GENESIS model for climate simulation. The WITCH model, which uses rigorous kinetic parameters and laws with provision for the effect on rates of deviation from equilibrium, can successfully simulate the depletion profiles in the soil for dolomite and albite if soil CO 2 is assumed to rise over the last 10 kyr up to about 30-40× the present atmospheric pressure, and if the solubility product of the Ca-smectite is assumed equal to that of an Fe(III)-rich Ca-montmorillonite. Such simulations document that dissolution behavior for silicates and carbonates are strongly coupled through pH, and for Ca-smectite and feldspars through dissolved silica. Such coupling is not incorporated in simple geometric and analytical models describing mineral dissolution, and therefore probably contributes to the long-standing observation of discrepancies among laboratory and field mineral dissolution rates.

  9. Response of the ocean, climate and terrestrial carbon cycle to Holocene freshwater discharge after 8 kyr BP

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Mysak, Lawrence A.

    2005-08-01

    The ``green'' McGill Paleoclimate Model is run from 8 to 0 kyr BP under variable insolation (Milankovitch forcing), Taylor Dome CO2 (radiative forcing) and four prescribed meltwater scenarios (freshwater forcing) due to the retreat of the Laurentide Ice Sheet (LIS). For each scenario, we constrain the total volume of meltwater to be 1.62 × 1015 m3 (sea level-equivalent of 4.62 m), which is obtained from the work of Paterson (1972) and the reconstructed sea level increase between 8 and 6 kyr BP. During each freshwater perturbation, the simulated maximum Atlantic meridional overturning circulation (MOC) intensity is reduced, by amounts of up to 8 Sv. During the time of a weakened MOC, the sea surface temperature is reduced in the high-latitude North Atlantic and increased in the Southern Ocean. Our model results indicate that the freshwater impact on the Holocene climate and terrestrial carbon cycle is likely negligible after the 8.2-kyr cold event. Only a large freshwater perturbation (>0.1 Sv) has a significant impact on the Holocene climate and terrestrial carbon cycle; it results in an enhanced cooling of about 1°C in the Northern Hemisphere (NH) and notable drops in the global net primary productivity (2 PgC/yr) and total land carbon storage (40 PgC).

  10. High Sedimentation Rate Paleomagnetic Records for the Last 70 kyrs From the Chilean Margin (ODP Sites 1233, 1234, 1235)

    NASA Astrophysics Data System (ADS)

    Stoner, J. S.; Lund, S.; Channell, J. E.; Mix, A. C.; Davies, M. H.; Lamy, F.

    2008-12-01

    Sediments that accumulate at around 1-m/kyr or greater preserve a paleomagnetic record that, under favorable conditions, may record the original geomagnetic input with little smoothing. However, such great rates of accumulation come with a price as features of interest are often deeply buried and may only be adequately recovered using drilling technologies. Here we present a full-vector geomagnetic reconstruction for the last 70,000 yrs from ultrahigh resolution records obtained through ODP drilling (Leg 202) on the Chilean Margin. ODP Site 1233 (41.0 S, 74.26 W, water depth 838 m) provides a 135-mcd u-channel derived directional paleomagnetic secular variation (PSV) and relative paleointensity (RPI) records. The chronology is constrained by AMS radiocarbon dates and tuning of alkenone sea surface temperature to Antarctic ice core temperature records back to 70,000 years BP. To the north, ODP Sites 1234 (36.13 S, 73.40W, water depth 1015 m) and 1235 (36.9 S, 73.33 W, water depth 489 m) provide independently dated shipboard and developing u-channel paleomagnetic records that reproduce many of the geomagnetic features observed at Site 1233 including excursions and high amplitude PSV intervals, while providing additional radiocarbon and isotopic constraints for development of a regional master chronology. All three Sites have exceptionally high glacial sedimentation rates that average 2-m/kyr for 1233, 80-cm/kyr for 1234 and 1-m/kyr for 1235. Fortuitously, the Laschamp magnetic excursion at Site 1233 occurs during an interval where sedimentation rates exceed 3-m/kyr. The Site 1233 chronology indicates that the Laschamp event, centered at 41,000 yrs BP, has a duration in reverse polarity of only 600 yrs, with polarity transitions occurring in less than 200 yrs within a 1500 yr long interval of low RPI. The path of virtual geomagnetic pole (VGP) positions for the Laschamp excursion at Site 1233 is generally consistent with the hypothesis of a simple field geometry

  11. Indian Ocean sea surface temperatures and vegetation change in SE African tropics during the past 800 Kyr

    NASA Astrophysics Data System (ADS)

    Castaneda, I. S.; Caley, T.; Dupont, L. M.; Kim, J.; Sinninghe Damsté, J. S.; Malaize, B.; Caillon, N.; Giraudeau, J.; Schouten, S.

    2011-12-01

    Presently, few vegetation records exist for the region of SE Africa that span multiple glacial-interglacial cycles yet such records can provide important insights into past continental climatic variability. Here, we examine vegetation and SST change in SE Africa from a ~800 Kyr sediment core (MD96-2048) collected from the continental shelf near the Limpopo River, which drains Botswana, southern Mozambique and northern South Africa. The coring site is located at 26°S and is likely situated outside of the influence of the Intertropical Convergence Zone (ITCZ). We find that plant leaf wax (n-alkane) carbon isotope (δ13C) and pollen records are in good agreement and exhibit pronounced glacial-interglacial variability. Relatively enriched n-alkane δ13C values are noted during glacial periods and reflect increased inputs of C4 vegetation, coincident with higher percentages of Poaceae (grass) pollen and cooler SST. Conversely, during interglacials, relatively depleted n-alkane δ13C values are noted and coincide with higher percentages of woodland and forest pollen and warmer SST. Previous studies of this core demonstrated that SST and salinity records based on both inorganic (δ18O and Mg/Ca) and organic (Uk'37 and TEX86) geochemical proxies display strong obliquity-driven 41-Kyr cycles, that are nearly in phase with annual mean insolation and air temperature at the high southern latitudes (Caley et al., 2011). Likewise, the n-alkane δ13C record was found to contain a strong 41-Kyr obliquity cycle. Interestingly, a strong 23-Kyr precession cycle is also present in the n-alkane δ13C record, that is nearly in phase with precession minima. Our results therefore suggest that vegetation change in this region reflects the dual influence of both southern and northern high-latitude climate forcings. In contrast to the Lake Malawi (East Africa) pollen record, which indicates a treeless landscape and extreme aridity from 105-90-Kyr (Beuning et al., 2011), the pollen record of

  12. Dome collapse eruption in Tatun Volcanic Group near metropolitan Taipei, Taiwan at ~6 kyrs

    NASA Astrophysics Data System (ADS)

    Chen, C.; Lee, T.

    2010-12-01

    The Tatun Volcanic Group (TVG) is located in the north of metropolitan Taipei, Taiwan. Over 6 million inhabitants are living in Taipei City and suburban area. Another critical issue is an international airport and two nuclear power plants are lying at the foot of the TVG. If the TGV will be re-active, the serious hazard for human lives and economies in this area will definitely occur. Understanding the youngest eruption history of the TVG will be much important for prediction the future activity of eruption. The core was collected from the Dream Lake at the eastern slop of Cising Mt.. Total 21 samples from depth 190 cm to 231.5 cm have been tested. Comparison of chemical compositions of glass and minerals in the volcanic clasts with those of lava around TVG, they clearly showed that the volcanic clasts can be correlated with the eruption of the closest Cising Mt. According to the radiocarbon (C-14) age of core sample at the depth 225 cm, the age was extrapolated around 6150 yrs ca. C-14 B.P.. Moreover, the respiratory cristobalite in the volcanic clasts were firstly identified by the identical morphology, chemical composition and Laser Raman Spectrometry (LRS). The crystalline silica was produced by vapor-phase crystallization and devitrification in the andesite lava dome and volcanic ash generated by pyroclastic flows formed by lava dome collapse in Soufriere Hills volcano, Montserrat (Baxter et al.,1999). These new evidence demonstrated that there would probably have the lava dome collapse eruptions in the TVG in the last 6 kyrs. The result in this paper also sustained that the landslide caused by the weak phreatic eruption within the last 6000 yrs in the TVG (Belousov et al., 2010). It must further be noted that an efficient program of the volcanic hazard reduction should be practiced for the metropolitan Taipei and suburban area.

  13. Sea surface temperature reconstructions over the last 70 kyr off Portugal: Biomarker data and regional modeling

    NASA Astrophysics Data System (ADS)

    Darfeuil, Sophie; Ménot, Guillemette; Giraud, Xavier; Rostek, Frauke; Tachikawa, Kazuyo; Garcia, Marta; Bard, Édouard

    2016-01-01

    This study aims at providing robust temperature reconstructions for a key oceanographic setting in the North Atlantic and at understanding the nature of the temperature signal recorded by the two biomarkers Uk'37 and TEX86, considering season and depth of production. To do so, high-resolution signals of Uk'37 and TEX86 are determined for the last 70 kyr for core MD95-2042, located off Portugal. Signals of Uk'37 and TEX86 present a tight correlation, demonstrating a dominant temperature effect. Uk'37 signals correspond well to the annual mean sea surface temperature (SST), whereas TEXH86-derived temperatures are 5.6°C higher, which is unrealistically warm for this area. Unsuitable TEX86 global linear calibrations on the Iberian Margin may suggest a possible occurrence of archaeal communities with specific temperature response. To assess the impact of different season or depth of production of the biomarkers on the recorded temperature in the sediment, modeled temperature proxies (Tproxies) are introduced in a Regional Oceanic Modeling System and tested for different seasons (annual/summer/winter) and depths (surface and 0-200 m) of production for three climate modes (Present Day (PD), Last Glacial Maximum (LGM), and Heinrich Stadials (HS)). Similar temperature amplitudes between climate modes are found at MD95-2042 core site for observations, for both biomarkers, and for modeled annual surface production Tproxy: 5.5-7°C for ΔT(PD-LGM) and 3-4°C for ΔT(LGM-HS). Therefore, we propose a new TEXH86 regional calibration to reconstruct present and past annual mean SSTs on the Iberian Margin.

  14. Climate controls on savanna C3 and C4 expansion in Southern Africa during the last 36 kyr BP

    NASA Astrophysics Data System (ADS)

    Wang, Y. V.; Larsen, T.; Andersen, N.; Blanz, T.; Schneider, R. R.

    2010-12-01

    Savannahs contain a mixture of C3 and C4 vegetation, accounting for more than a quarter of global primary production and are the second most important biome on the continents. However, our understanding on how savannahs will respond to rising CO2 concentration and temperatures or the IPCC estimated decrease in rainfall is not yet clear in spite of potential far reaching socio-economic consequences. In this study, we used the δD and δ13C of sedimentary long-chain n-alkanes (n-C27,29,31,33 ) in concert with reconstructions for sea surface temperatures and fluvial discharge from a marine sediment core (GIK16160-3, 18°14.47’S, 37°52.27’W, 1334m water depth), collected near the Zambezi river mouth to examine savannah responses under different hydrological and climate conditions in Southern Africa during the last 36 kyr BP. Our data show large variability in both δD and δ13C records of the four n-alkanes, with isotopic differences between individual n-alkanes being far more pronounced during the Glacial than during the Deglacial and Holocene. These large differences may be explained by proportionally higher contributions of C4 grasses over C3 trees to the n-C33,31, which seems to be opposite for n-C29. A strong anticorrelation between δD and δ13C from 36 to 16 kyr BP for n-C31 (R2=0.55) and n-C33 (R2=0.70) suggests that δD of these n-alkanes is strongly influenced by changes in vegetation types as well as physiological effects, rather than being directly related to evaporation/ precipitation balance. In contrast, no apparent relationship (R2=0.32) exists between δD and δ13C of n-C29, suggesting that n-C29 is the most promising hydrological proxy due to less variable vegetation type contributions to n-C29 throughout the core. The C4 plant contribution, which was estimated by taking into account the four n-alkanes δ13C signals and their abundance, implies dominance of C4 grass between 36 and 20 kyr BP, and more evenly distributed C3 and C4 vegetation from

  15. Day Care Babies Catch Stomach Bugs Earlier, but Get Fewer Later

    MedlinePlus

    ... nlm.nih.gov/medlineplus/news/fullstory_158513.html Day Care Babies Catch Stomach Bugs Earlier, But Get ... TUESDAY, April 26, 2016 (HealthDay News) -- Babies in day care catch their first stomach bug earlier than ...

  16. Day Care Babies Catch Stomach Bugs Earlier, but Get Fewer Later

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_158513.html Day Care Babies Catch Stomach Bugs Earlier, But Get ... TUESDAY, April 26, 2016 (HealthDay News) -- Babies in day care catch their first stomach bug earlier than ...

  17. Scar revision

    PubMed Central

    Sharma, Mohit; Wakure, Abhijeet

    2013-01-01

    Most surgical patients end up with a scar and most of these would want at least some improvement in the appearance of the scar. Using sound techniques for wound closure surgeons can, to a certain extent, prevent suboptimal scars. This article reviews the principles of prevention and treatment of suboptimal scars. Surgical techniques of scar revision, i.e., Z plasty, W plasty, and geometrical broken line closure are described. Post-operative care and other adjuvant therapies of scars are described. A short description of dermabrasion and lasers for management of scars is given. It is hoped that this review helps the surgeon to formulate a comprehensive plan for management of scars of these patients. PMID:24516292

  18. Dust fertilization of biological productivity in the Subarctic North Pacific during the last 150 kyr

    NASA Astrophysics Data System (ADS)

    Serno, S.; Winckler, G.; Anderson, R. F.; Ren, H. A.; Hayes, C.; Machalett, B.; Gersonde, R.; Haug, G. H.

    2012-12-01

    The Subarctic North Pacific (SNP) is one of three principal High Nutrient Low Chlorophyll regions of the modern ocean characterized by an excess pool of macronutrients not completely consumed during the annual biogeochemical cycle. In the last 25 years, a number of studies from the SNP have proposed that eolian dust input of iron from East Asian arid regions is the major limiting factor for primary and export production. In recent years, additional iron sources have been suggested for regulating phytoplankton growth in the SNP, including mobilized continental margin material, ice-rafted debris, volcanic material, turbulent mixing and upwelling. We will present results of a multi-proxy approach from INOPEX core SO202-7-6 and ODP site 882 from the Detroit Seamount in the northwest SNP covering the last 30 and 150 kyr, respectively. We will compare 230Th-normalized dust flux records based on 4He, 232Th and REE, grain size distributions and 230Th-normalized fluxes of opal, total organic carbon, carbonate and biogenic barium and Pa/Th ratios as productivity proxies for INOPEX core SO202-7-6. A new high resolution record of dust fluxes based on 4He will be compared with published productivity proxy records from ODP site 882. A spatial survey of core-top sediments covering the whole SNP indicates that the efficiency of diatom export out of the euphotic zone, as defined by the ratio of opal flux in the core-top sediments to the maximum annual surface water silicate concentration during the winter months, is positively correlated with dust fluxes, possibly as a result of either dust fertilization of primary production or a diatom ballasting effect by dust particles. Preliminary results from INOPEX core SO202-7-6, on the other hand, indicate no correlation between dust flux and biological productivity during the last deglaciation. We will discuss possible explanations for these observations to answer the question if the dust fertilization hypothesis proposed by John Martin

  19. Stalagmite Survival: 500kyr of Cyclical Growth and Natural Attrition of Stalagmites in Sulawesi

    NASA Astrophysics Data System (ADS)

    Scroxton, N.; Gagan, M. K.; Dunbar, G. B.; Ayliffe, L. K.; Hantoro, W. S.; Shen, C. C.; Hellstrom, J. C.; Zhao, J. X.; Cheng, H.; Edwards, R. L.; Sun, H.; Rifai, H.

    2014-12-01

    Numerous speleothem studies have analysed the age distribution of stalagmites harvested from multiple caves and inferred important changes in paleoclimates to explain stalagmite growth phases. However, stalagmites take tens to hundreds of thousands of years to grow, and thus the twin desires to preserve the cave condition for future generations and advance palaeoclimate science are often in conflict. In this study we use U/Th ages from low impact mini-cores extracted in situ from the bases of stalagmites, thus keeping the intrinsic value of the cave intact. Our case study is based on 77 individual stalagmites drilled in situ in thirteen caves located in and around Bantimurung-Bulusaraung National Park, South Sulawesi, Indonesia. The stalagmites grew during discrete time intervals within the last ~530,000 years, and analysis of their age distribution shows an exponential decrease in the number of older stalagmites surviving to the present day. The age distribution indicates that the rate of natural attrition of stalagmites is approximately constant through time, probably in response to a number of natural processes, including downward erosion of the karst terrain, cave collapse, in-cave erosional processes and in-cave sedimentation covering stalagmites. Natural attrition of stalagmites is likely to be a general cave phenomenon, and has important implications for cave conservation because it highlights that random removal of stalagmites without prior knowledge of their ages will result in unnecessary replication and a failure to sample the full length of the available paleoclimate record. Departure from this "normal" exponential profile can be used to infer palaeoclimate information: significant deviations are produced by periods of more frequent stalagmite growth, inferred here to reflect increases in monsoon rainfall over Sulawesi (345-340, 75-70 and 10-5 kyr BP). By adjusting the record to account for stalagmite attrition, more statistically robust paleoclimate

  20. Volcanic synchronization of Dome Fuji and Dome C Antarctic deep ice cores over the past 216 kyr

    NASA Astrophysics Data System (ADS)

    Fujita, S.; Parrenin, F.; Severi, M.; Motoyama, H.; Wolff, E.

    2015-02-01

    Two deep ice cores, Dome Fuji (DF) and EPICA Dome C (EDC), drilled at remote dome summits in Antarctica, were synchronized to better understand their chronology. A total of 1401 volcanic tie points were identified covering the past 216 kyr. DFO2006, the chronology for the DF core characterized by strong constraining by the O2/N2 age markers, was compared with AICC2012, the chronology for 5 cores including the EDC core, and characterized by glaciological approaches combining ice flow modelling with various age markers. The age gaps between the two chronologies are within 2 kyr, except at Marine Isotope Stage (MIS) 5. DFO2006 gives ages older than AICC2012, with peak values of the gap of 4.5 and 3.1 kyr at MIS 5d and MIS 5b, respectively. Accordingly, ratios of duration DFO2006/AICC2012 are 85% at a period from the late stage of MIS 6 to MIS 5d and 114% at a period from MIS 5d to 5b. We then compared the DFO2006 with another chronology of the DF core, DFGT2006, characterized by glaciological approaches with weaker constraining by age markers. Features of the DFO2006/DFGT2006 age gaps are very similar to those of the DFO2006/AICC2012 age gaps. This fact lead us to hypothesize that a cause of the systematic DFO2006/AICC2012 age gaps at MIS 5 are associated with differences in the dating approaches. Besides, ages of speleothem records from China agreed well with DFO2006 at MIS 5c and 5d but not at MIS 5b. Thus, we hypothesize at least at MIS 5c and 5d, major sources of the gaps are systematic errors in surface mass balance estimation in the glaciological approach. Compatibility of the age markers should be carefully assessed in future.

  1. Volcanic synchronization of Dome Fuji and Dome C Antarctic deep ice cores over the past 216 kyr

    NASA Astrophysics Data System (ADS)

    Fujita, S.; Parrenin, F.; Severi, M.; Motoyama, H.; Wolff, E. W.

    2015-10-01

    Two deep ice cores, Dome Fuji (DF) and EPICA Dome C (EDC), drilled at remote dome summits in Antarctica, were volcanically synchronized to improve our understanding of their chronologies. Within the past 216 kyr, 1401 volcanic tie points have been identified. DFO2006 is the chronology for the DF core that strictly follows O2 / N2 age constraints with interpolation using an ice flow model. AICC2012 is the chronology for five cores, including the EDC core, and is characterized by glaciological approaches combining ice flow modelling with various age markers. A precise comparison between the two chronologies was performed. The age differences between them are within 2 kyr, except at Marine Isotope Stage (MIS) 5. DFO2006 gives ages older than AICC2012, with peak values of 4.5 and 3.1 kyr at MIS 5d and MIS 5b, respectively. Accordingly, the ratios of duration (AICC2012 / DFO2006) range between 1.4 at MIS 5e and 0.7 at MIS 5a. When making a comparison with accurately dated speleothem records, the age of DFO2006 agrees well at MIS 5d, while the age of AICC2012 agrees well at MIS 5b, supporting their accuracy at these stages. In addition, we found that glaciological approaches tend to give chronologies with younger ages and with longer durations than age markers suggest at MIS 5d-6. Therefore, we hypothesize that the causes of the DFO2006-AICC2012 age differences at MIS 5 are (i) overestimation in surface mass balance at around MIS 5d-6 in the glaciological approach and (ii) an error in one of the O2 / N2 age constraints by ~ 3 kyr at MIS 5b. Overall, we improved our knowledge of the timing and duration of climatic stages at MIS 5. This new understanding will be incorporated into the production of the next common age scale. Additionally, we found that the deuterium signals of ice, δDice, at DF tends to lead the one at EDC, with the DF lead being more pronounced during cold periods. The lead of DF is by +710 years (maximum) at MIS 5d, -230 years (minimum) at MIS 7a and +60

  2. Revision sphenoidethmoidectomy.

    PubMed

    Eichel, B S

    1985-03-01

    In 1981, a series of 236 intranasal ethmoidectomy (INE) procedures was reported with a complication rate of 1.8%. Special attention has subsequently been directed to the surgical failures; namely, recurrent nasal polyposis which accounted for approximately 17%. The reason for recurrence in most instances was felt due to failure to do a more thorough posterior ethmoidectomy and enter and clean out the sphenoid sinuses. Subsequently, in all revision cases where a more thorough sphenoidethmoidectomy (RSE) was performed, the overall long-term success rate raised to better than 90%. Attention to skeletonizing the middle turbinate by stripping mucosa and leaving a thin bony shell is an important technical factor. An attempt is made to leave some of this bony skeletonized medial wall of the middle turbinate as it represents the most crucial landmark in doing the surgery via the intranasal route. There still remains approximately 8% to 10% of this patient population with nasal polyposis and sinusitis of such severity that surgery has offered only a temporary measure of relief. In dealing with this group it may be necessary to see these patients postoperatively at four to six-week intervals, carefully suctioning the ethmoid labyrinth and occasionally doing minor office "touch-up" ethmoidectomy-polypectomy procedures to clean off redundant mucosa or early polyposis. This paper is written to offer a compromise to the two schools of intranasal ethmoidectomy surgery as to the necessity of removing the middle turbinate in its entirety. PMID:3974381

  3. A 400 kyr record of combustion oxygen demand in the western equatorial Pacific: Evidence for a precessionally forced climate response

    NASA Astrophysics Data System (ADS)

    Perks, Helen M.; Keeling, Ralph F.

    1998-02-01

    We have developed a combustion analysis technique for sediments which measures the amount of O2 consumed by the reduced species. We have measured this quantity, which we call "combustion oxygen demand (COD)," on a carbonate-rich sediment core from the Ontong-Java Plateau in the western equatorial Pacific back to marine oxygen isotope stage 11. The precision of the COD technique is ±6.3 µmol O2 g-1, which corresponds to ˜±0.0076% wt Corg, assuming oxidation of organic carbon dominates the signal. The COD time series is characterized by values which are about twice as high during glacials as during interglacials, the largest shift occurring from 401 µmol O2 g-1 in midstage 6 to 144 µmol O2 g-1 at 5e, and is coherent with the oxygen isotope curve of Globigerinoides sacculifer in the same core at the Milankovitch frequencies of 100 and 41 kyr. Pronounced variations in the 19-23 kyr band suggest that the climate of the western equatorial Pacific is sensitive to precessional forcing, a response not apparent from other records obtained in this region.

  4. Silicic Eruptions of the Past 50 kyr at the Three Sisters Volcanic Cluster

    NASA Astrophysics Data System (ADS)

    Calvert, A. T.; Hildreth, W.; Fierstein, J.

    2003-12-01

    The Three Sisters volcanic cluster in the central Oregon Cascades consists of mafic to intermediate stratovolcanoes surrounded by mafic and silicic flows and domes. The bulk of South and Middle Sister are late Pleistocene while North Sister is middle Pleistocene (Schmidt and Grunder, 2003 GSA abs.). Thick rhyolite and dacite lava flows and domes are rich in potassium, and young glaciation exposes holocrystalline groundmass textures ideal for argon geochronology. Several of these silicic flows bracket stratovolcano growth, and precise geochronology illuminates a rich basalt to rhyolite history in the cluster over the past 50 kyr. Careful step-heating 40Ar/39Ar experiments yield excellent plateau ages with radiogenic yields often above 5% on rocks as young as 20 ka. Most samples have well-determined isochrons with atmospheric (40/36 = 295.5) intercepts, although several have intercepts as low as 286. South Sister is a composite cone with an andesite/dacite base (Hodge Crest) and a young andesite summit sequence. The basal flow of the 300m-thick, youngest conformable stack of andesite lavas at the summit is 27+/-3 ka. Unconformably underlying portions date back to at least 50 ka based on ages of overlapping silicic flows. The base of Middle Sister is andesite overlain by ˜300m of olivine basalt. Some Middle Sister andesites and all basalts overlie a distinctive dacite agglutinate (20+/-2 ka) in the South/Middle Sister saddle. All Middle Sister lavas underlie a thick dacite flow (14+/-3 ka) that vented at 8500 ft (2600m) on its S flank. Dacite lava flows erupted from the Middle/North Sister saddle at 27+/-2 and 18+/-2 ka. Additionally, several >100m-thick rhyolite and dacite lavas vented low on the flanks of the cluster. Obsidian Cliff rhyolite (37.8+/-1.8 ka) and Lane Plateau dacite (21.4+/-1.9 ka) erupted W of Middle Sister, the Dew Lake dacite (32.3+/-1.8 ka) located near the locus of the INSAR anomaly W of South Sister flowed around a 148+/-4 ka (knob 6482) basalt

  5. Observation of 23 Supernovae that Exploded <300 pc from Earth During the Past 300 kyr in the Radiocarbon and 10Be Cosmogenic Isotope Record

    NASA Astrophysics Data System (ADS)

    Firestone, R. B.

    2014-12-01

    The global excess radiocarbon abundance record for the past 50 kyr can be entirely explained by the explosion of four supernovae 44, 37, 32, and 22 kyr ago less than 250 pc from Earth. Each supernova left a nearly identical signature beginning with a sudden increase at the time of the explosion, followed by a hiatus of 1500 years, and continuing with a sustained, 2000 year increase in radiocarbon from gamma rays produced by diffusive shock in the supernova remnant. For the past 18 kyr excess radiocarbon from SN22kyrBP, identified as the Vela supernova, has decayed with the 5700 year half-life of 14C. The absolute scale for radiocarbon abundance has been determined from the decay curve as Δ14C=5±2% in 1950. Small oscillations in the decay curve are shown to coincide with variations in Earth's Virtual Axial Dipole Moment (VADM). SN44kyrBP exploded approximately 110 pc from Earth doubling the radiocarbon abundance. These supernovae are confirmed in the 10Be, 26Al, 36Cl and nitrate geological records. An additional 19 supernovae are observed 50-300 kyr ago in the 10Be record. Using the Earth as a calorimeter I have determined that approximated 2×1049 ergs were released at the time of each supernova explosion and 1049-50 ergs afterwards, consistent with theoretical predictions. The background rate of radiocarbon productions from more distant sources was determined as 1.61 atoms/cm2s at the top of the atmosphere. Although little danger to life on Earth is expected from these supernovae, each of the recent events were shown to correlate with concurrent global warming of 3-4°C.

  6. The Environmental impact of the 8.2 and 9.2 kyr events in the UK.

    NASA Astrophysics Data System (ADS)

    Jones, Richard; Reinhardt, Liam; Halloran, Paul; Hatton, Jackie; Marshall, Jim

    2015-04-01

    The instability of the Early Holocene climate in NW Europe is due in part to the impact of freshwater pulses in the North Atlantic disrupting thermohaline circulation and reducing the northward transport of heat. Two of the most significant climatic episodes are the 8.2 and 9.2 kyr events, characterised by significant oxygen isotopic excursions in NW European lacustrine and speleothem records, the Greenland Ice-core record and changing SSTs in the North Atlantic sector. Assessing the impact of these two events on terrestrial systems is problematic due to the difficulty in identifying their signature in terrestrial archives. A sub-decadal oxygen isotope record from a Holocene micrite core from Hawes Water NW England provides unambiguous evidence for two significant isotopic excursions equivalent to the 9.2 and 8.2 kyr events. Lasting 50 and 150 yr respectively they are characterised by a slight cooling of around 1.6oC in mean July air temperatures (chironomid inferred). The environmental impact of each event was minimal, with no evidence for any significant changes in the range or abundance of plant taxa and no evidence for catchment instability. These results support the idea that the 8.2 and 9.2 kyr events are primarily a reflection of the changing isotopic composition of meteoric precipitation (δ18Op) and in the UK at least were of limited environmental significance. Analysis of subpolar gyre behaviour and atmospheric circulation across preindustrial control simulations from CMIP5, suggest that the negative isotopic excursions recorded at Hawes Water most likely reflect the influx of isotopically lighter moisture from the Arctic. An influx of freshwater down the Hudson River and into the North Atlantic Current could result in the development of low pressure anomalies over Scandinavia, bringing arctic air and moisture to the UK. This could be expected to produce the relatively minor decline in summer temperatures but would result in the significant negative shift

  7. Radiolarians, foraminifers, and biostratigraphy of the Coniacian-Campanian deposits of the Alan-Kyr Section, Crimean Mountains

    NASA Astrophysics Data System (ADS)

    Bragina, L. G.; Beniamovsky, V. N.; Kopaevich, L. F.

    2016-01-01

    Data on the distribution of radiolarians and planktonic and benthic foraminifers are obtained for the first time from the Alan-Kyr Section (Coniacian-Campanian), in the central regions of the Crimean Mountains. Radiolarian biostrata, previously established from Ak-Kaya Mountain (central regions of the Crimean Mountains) were traced: Alievium praegallowayi-Crucella plana (upper Coniacian-lower Santonian), Alievium gallowayi-Crucella espartoensis (upper Santonian without the topmost part), and Dictyocephalus (Dictyocryphalus) (?) legumen-Spongosaturninus parvulus (upper part of the upper Santonian). Radiolarians from the Santonian-Campanian boundary beds of the Crimean Mountains are studied for the first time, and Prunobrachium sp. ex gr. crassum-Diacanthocapsa acanthica Beds (uppermost Santonian-lower Campanian) are recognized. Bolivinoides strigillatus Beds (upper Santonian) and Stensioeina pommerana-Anomalinoides (?) insignis Beds (upper part of the upper Santonian-lower part of the lower Campanian) are recognized. Eouvigerina aspera denticulocarinata Beds (middle and upper parts of the lower Campanian) and Angulogavelinella gracilis Beds (upper part of the upper Campanian are recognized on the basis of benthic foraminifers. These beds correspond to the synchronous biostrata of the East European Platform and Mangyshlak. Marginotruncana coronata- Concavatotruncana concavata Beds (Coniacian-upper Santonian), Globotruncanita elevata Beds (terminal Santonian), and Globotruncana arca Beds (lower Campanian) are recognized on the basis of planktonic foraminifers. Radiolarian and planktonic and benthic foraminiferal data agree with one another. The position of the Santonian-Campanian boundary in the Alan-Kyr Section, which is located stratigraphically above the levels of the latest occurrence of Concavatotruncana concavata and representatives of the genus Marginotruncana, is refined, i.e., at the level of the first appearance of Globotruncana arca. A gap in the Middle

  8. Impact of climate variability on terrestrial environment in Western Europe between 45 and 9 kyr cal. BP: vegetation dynamics recorded by the Bergsee Lake (Black Forest, Germany).

    NASA Astrophysics Data System (ADS)

    Duprat-Oualid, Fanny; Begeot, Carole; Rius, Damien; Millet, Laurent; Magny, Michel

    2016-04-01

    Between 9 and 45 kyr cal. BP, two great transitions lead the global climate system to evolve from the Last-Glacial period (115-14.7 kyr cal. BP), to two successive warmer periods, the Late-Glacial Interstadial (14.7-11.7 kyr cal. BP) and the Holocene (11.7-0 kyr cal. BP). δ18O variations recorded in Greenland ice cores (GRIP & NGRIP) revealed high frequency climate variability within the Last Glacial. These reference isotopic records highlighted a succession of centennial-to-millennial warm/cold events, the so-called Greenland Interstadials (GI) and Greenland Stadials (GS). The number continental records about the period 14.7-0 kyr cal. BP is substantial. This allowed to understand the vegetation dynamics in response to climate changes this period at the North-Atlantic scale. However, sequences covering the glacial period (beyond 20 kyr cal.BP) remain rare, because of hiatuses mostly due to local glaciers. Therefore, sedimentary continuous records of vegetation dynamics are still needed to better understand climate changes during the Last Glacial in Western Europe (Heiri et al. 2014). Here we present a new high-resolution pollen record from Lake Bergsee (47°34'20''N, 7°56'11''E, 382 m a.s.l). This lake is located south of Black Forest and north of the Alps, beyond the zone of glaciers maximal extension. Therefore it could have recorded the whole last climatic cycle, i.e. 120-0 kyr cal. BP. In 2013, a 29 m long core was extracted from the Bergsee. According to the depth-age model based on 14C AMS dating and the Laacher See Tephra (LST), the record spans continuously at least the last 45 kyrs. The first series of pollen analysis, focused on the 45-9 kyr cal. BP time window, allows us to reconstruct a precise, faithful and continuous vegetation history at the centennial scale. This high temporal resolution enabled to assess the response of vegetation to secular climate events (e.g. GI-4 = 200 yrs). First, our results show that vegetation responded to climate

  9. The Padua Inventory: Do Revisions Need Revision?

    ERIC Educational Resources Information Center

    Gonner, Sascha; Ecker, Willi; Leonhart, Rainer

    2010-01-01

    The purpose of the present study was to examine the psychometric properties, factorial structure, and validity of the Padua Inventory-Washington State University Revision and of the Padua Inventory-Revised in a large sample of patients with obsessive-compulsive disorder (n = 228) and with anxiety disorders and/or depression (n = 213). The…

  10. Copyright Revision in Canada

    ERIC Educational Resources Information Center

    Keyes, A. A.

    1977-01-01

    The article discusses the history of copyright laws, the directions which copyright revision can take, and the rationale behind revision. Regulations for protecting various media such as sound recordings, performances, and cable television are discussed. (JAB)

  11. Sea ice and millennial-scale climate variability in the Nordic seas 90 kyr ago to present

    NASA Astrophysics Data System (ADS)

    Hoff, Ulrike; Rasmussen, Tine L.; Stein, Ruediger; Ezat, Mohamed M.; Fahl, Kirsten

    2016-07-01

    In the light of rapidly diminishing sea ice cover in the Arctic during the present atmospheric warming, it is imperative to study the distribution of sea ice in the past in relation to rapid climate change. Here we focus on glacial millennial-scale climatic events (Dansgaard/Oeschger events) using the sea ice proxy IP25 in combination with phytoplankton proxy data and quantification of diatom species in a record from the southeast Norwegian Sea. We demonstrate that expansion and retreat of sea ice varies consistently in pace with the rapid climate changes 90 kyr ago to present. Sea ice retreats abruptly at the start of warm interstadials, but spreads rapidly during cooling phases of the interstadials and becomes near perennial and perennial during cold stadials and Heinrich events, respectively. Low-salinity surface water and the sea ice edge spreads to the Greenland-Scotland Ridge, and during the largest Heinrich events, probably far into the Atlantic Ocean.

  12. Cosmic airburst debris, climate anomalies and societal reactions at 4.2kyr BP: from North Syria to Adelie Land

    NASA Astrophysics Data System (ADS)

    Coqueugniot, E.; Courty, M. M.

    2012-12-01

    The linkages established between dust spikes, unprecedented drought and societal disruption at 4.2 kyr BP have yet failed elucidating the marked increase in aerosol. The volcanic dust component or the erratic spatial pattern are among other puzzling anomalies for a global climate event. We examine here the 4.2 kyr BP debris records from high quality sedimentary archives across the two hemispheres: (1) at Tell Dja'de (Syria), a carbonaceous surface sealed by a EB III/IV Bronze age cemetery; (2) at Tell Ahmar (Syria), the nearly intact collapsed wood frame of the Akkad palace sandwiched between the last 3rd millennium BC plastered floors and massive destruction layers of the monumental buildings; (3) debris accumulation from human processed slags in late Akkaddian contexts at Tell Leilan, Tell Chuera, Tell Beydar, Tell Brak (North Syria) and in an EB III/IV one at Umbaschi (South Syria); (4) a tsunami layer at Banda Aceh (Sumatra); (5) deep sea cores from the Mediterranean and Caspian seas, the Indian and Austral oceans. Using an in situ multi-analytical protocol, we focus on the carbonaceous polymorphs and the composite elements that we formerly defined to tracing hypervelocity cosmic airbursts. A meticulous control of their spatial pattern and structural characteristics at meso to nano-scales has helped to distinguishing the intact debris fall of airburst origin from their human processed-byproducts. The later trace the occurrence in the debris airbursts of highly valuable resources, i.e. fossil combustible with singular properties, that have been exploited since the prehistoric time. Evidence for an oceanic impact at 4.2 kyr BP in the Austral ocean are provided by the 3 m record in the Adelie land high resolution marine core (MD03-2601) showing sudden discharge of ice rafted fine debris with impact features. Their fresh fingerprints in the high to low latitude records from the southern hemisphere indicate massive dispersion of impact debris by air and surface

  13. Stratigraphic Correlation of an Excursion at 22 kyr in the U.S. Great Basin - the Hilina Pali Excursion?

    NASA Astrophysics Data System (ADS)

    Liddicoat, J. C.; Coe, R. S.

    2013-12-01

    An unusually large secular variation of the geomagnetic field recorded in outcrops of pluvial Lake Russell sediment about 22 kyr old in the Mono Basin, CA, can be used for precise correlation to other lacustrine sections in the western U.S., and perhaps beyond. We present new AF and thermal demagnetization results for paired samples at 2-cm intervals between ash layers 7 and 8 of Lajoie (1968) in the bank of Wilson Creek that document an excursion having an inclination as low as 16 degrees and as high as 73 degrees, while the declination swings from 15 degrees west during the low inclination to 30 east when the inclination is high, and back to average northerly declination and expected inclination. The corresponding VGPs form a narrow clockwise-trending loop centered at about 50 N, 30 E. The Mono Lake Excursion (MLE; Liddicoat and Coe, 1979) occurs 1.7 m lower in the same section. The best estimates for the ages of the two excursions are about 22 and 32 kyr, based on 14-C dates (Cassata et al., 2010). About 150 km to the north, sediments of about the same age exposed along the Truckee River that were deposited in pluvial Lake Lahontan record a similar geomagnetic signature. Moreover, both the MLE and this excursion are exhibited at the appropriate levels in a sediment core taken from Pyramid Lake, the remnant of Lake Lahontan (Benson et al., 2008). Thus, this excursion is a valuable marker for high-resolution correlation of Quaternary sediments in the western U.S., especially when paired with the MLE. It is tempting to try to identify this geomagnetic feature with others of about the same age further away. On the island of Hawaii, Coe et al. (1978) discovered a lava flow on the Hilina Pali with a calibrated 14-C age of 21 +/-1 kyr that has an inclination about 30 degrees shallower and a paleointensity 60 percent lower than today. Later Teanby et al. (2002) documented an excursion with inclinations as low as -35 degrees, recorded by around 40 successive flows with

  14. Teasing Apart Regional Climate and Meltwater Influences on Florida Straits Sea Surface Temperature and Salinity over the past 40 kyr

    NASA Astrophysics Data System (ADS)

    Schmidt, M. W.; Lynch-Stieglitz, J.

    2008-12-01

    Recent reconstructions of North Atlantic salinity variability over the last glacial cycle show that abrupt climate events are linked to major reorganizations in the low-latitude hydrologic cycle, affecting large-scale changes in evaporation minus precipitation (E-P) patterns. Although there is general agreement that the Intertropical Convergence Zone (ITCZ) migrates southward during cold stadials, it remains unclear how this shift affects the net E-P budget in the North Atlantic. In order to reconstruct a high resolution record of past sea surface temperature (SST) and salinity (SSS) in the Florida Straits across abrupt climate events of the last 40 kyr, we combine Mg/Ca paleothermometry and δ18O measurements in shells from the surface-dwelling foraminifera Globigerinoides ruber in cores KNR166-2-JPC29 (24°17'N, 83°16'W; 648 m depth; 8-20 cm/kyr sed. rate) and JPC26 (24°19.61'N, 83°15.14'W; 546 m depth; 18-240 cm/kyr sed. rate) and calculate δ18OSEAWATER (δ18OSW) variability. Removal of the δ18OSW signal due to continental ice volume variation results in the ice volume-free (IVF) δ18OSW record (a proxy for SSS variability). Although most waters flowing through the Florida Straits today originate in the tropical western Atlantic, major meltwater discharges from the Mississippi River across the last deglacial period also influenced SST and SSS in the Florida Straits. To constrain periods of increased meltwater discharge, we measured Ba/Ca ratios in G. ruber from select intervals. Because riverine waters have a much higher dissolved Ba+2 concentration relative to seawater, foraminifera Ba/Ca ratios can be used as an additional proxy to constrain periods of increase riverine discharge. Initial results suggest the hydrographic history of the Florida Straits is influenced by both meltwater discharge and regional climate variability linked to the high-latitude North Atlantic. Both the IVF- δ18OSW and Ba/Ca records reveal a prolonged period from 16.0-13.0 kyr

  15. Changes in dominant moisture sources and the consequences for hydroclimate on the northeastern Tibetan Plateau during the past 32 kyr

    NASA Astrophysics Data System (ADS)

    Thomas, Elizabeth K.; Huang, Yongsong; Clemens, Steven C.; Colman, Steven M.; Morrill, Carrie; Wegener, Pamela; Zhao, Jiangtao

    2016-01-01

    Lake Qinghai, located on the northeastern Tibetan Plateau north of the modern maximum summer monsoon extent, is well situated to record northward advances of the summer monsoon. Existing paleoclimate records contain conflicting evidence for the timing of summer monsoon advance into this region: an early arrival pre-Younger Dryas or a late arrival at the beginning of the Holocene. A 30-kyr-long leaf wax hydrogen isotope (n-alkanoic acid, δ2Hwax) record from Lake Qinghai helps to address this discrepancy by elucidating changes in the three main moisture sources in this region: southerly (summer monsoon), northwesterly, and local precipitation. Lake Qinghai δ2Hwax indicates that the arid glacial period was dominated by northwesterly moisture. Extremely arid conditions prevailed from 15 to 14 ka, likely because westerly winds were weakening and the summer monsoon had not yet reached this region. This arid period ended by 13.6 ka when small amounts of summer monsoon precipitation reached Lake Qinghai. Summer monsoon moisture subsequently retreated off of the northeastern Tibetan Plateau during the Younger Dryas and re-advanced in the early Holocene. Summer monsoon precipitation decreased progressively throughout the Holocene in response to decreasing summer insolation, and the modern northwesterly- and local-dominated moisture regime was attained ca. 2.6 ka. Lake Qinghai δ2Hwax demonstrates that the summer monsoon extent was dynamic during the past 30 kyr, responding dramatically to insolation and North Atlantic circulation changes. Moreover, Lake Qinghai δ2Hwax demonstrates that local and northwesterly air masses are important moisture sources to the northeastern Tibetan Plateau, and should be considered when reconstructing past hydroclimate in this region.

  16. Integrated Tree-Ring-Radiocarbon High-Resolution Timeframe to Resolve Earlier Second Millennium BCE Mesopotamian Chronology.

    PubMed

    Manning, Sturt W; Griggs, Carol B; Lorentzen, Brita; Barjamovic, Gojko; Ramsey, Christopher Bronk; Kromer, Bernd; Wild, Eva Maria

    2016-01-01

    500 years of ancient Near Eastern history from the earlier second millennium BCE, including such pivotal figures as Hammurabi of Babylon, Šamši-Adad I (who conquered Aššur) and Zimrilim of Mari, has long floated in calendar time subject to rival chronological schemes up to 150+ years apart. Texts preserved on clay tablets provide much information, including some astronomical references, but despite 100+ years of scholarly effort, chronological resolution has proved impossible. Documents linked with specific Assyrian officials and rulers have been found and associated with archaeological wood samples at Kültepe and Acemhöyük in Turkey, and offer the potential to resolve this long-running problem. Here we show that previous work using tree-ring dating to place these timbers in absolute time has fundamental problems with key dendrochronological crossdates due to small sample numbers in overlapping years and insufficient critical assessment. To address, we have integrated secure dendrochronological sequences directly with radiocarbon (14C) measurements to achieve tightly resolved absolute (calendar) chronological associations and identify the secure links of this tree-ring chronology with the archaeological-historical evidence. The revised tree-ring-sequenced 14C time-series for Kültepe and Acemhöyük is compatible only with the so-called Middle Chronology and not with the rival High, Low or New Chronologies. This finding provides a robust resolution to a century of uncertainty in Mesopotamian chronology and scholarship, and a secure basis for construction of a coherent timeframe and history across the Near East and East Mediterranean in the earlier second millennium BCE. Our re-dating also affects an unusual tree-ring growth anomaly in wood from Porsuk, Turkey, previously tentatively associated with the Minoan eruption of the Santorini volcano. This tree-ring growth anomaly is now directly dated ~1681-1673 BCE (68.2% highest posterior density range), ~20

  17. Integrated Tree-Ring-Radiocarbon High-Resolution Timeframe to Resolve Earlier Second Millennium BCE Mesopotamian Chronology

    PubMed Central

    Griggs, Carol B.; Lorentzen, Brita; Barjamovic, Gojko; Ramsey, Christopher Bronk; Kromer, Bernd; Wild, Eva Maria

    2016-01-01

    500 years of ancient Near Eastern history from the earlier second millennium BCE, including such pivotal figures as Hammurabi of Babylon, Šamši-Adad I (who conquered Aššur) and Zimrilim of Mari, has long floated in calendar time subject to rival chronological schemes up to 150+ years apart. Texts preserved on clay tablets provide much information, including some astronomical references, but despite 100+ years of scholarly effort, chronological resolution has proved impossible. Documents linked with specific Assyrian officials and rulers have been found and associated with archaeological wood samples at Kültepe and Acemhöyük in Turkey, and offer the potential to resolve this long-running problem. Here we show that previous work using tree-ring dating to place these timbers in absolute time has fundamental problems with key dendrochronological crossdates due to small sample numbers in overlapping years and insufficient critical assessment. To address, we have integrated secure dendrochronological sequences directly with radiocarbon (14C) measurements to achieve tightly resolved absolute (calendar) chronological associations and identify the secure links of this tree-ring chronology with the archaeological-historical evidence. The revised tree-ring-sequenced 14C time-series for Kültepe and Acemhöyük is compatible only with the so-called Middle Chronology and not with the rival High, Low or New Chronologies. This finding provides a robust resolution to a century of uncertainty in Mesopotamian chronology and scholarship, and a secure basis for construction of a coherent timeframe and history across the Near East and East Mediterranean in the earlier second millennium BCE. Our re-dating also affects an unusual tree-ring growth anomaly in wood from Porsuk, Turkey, previously tentatively associated with the Minoan eruption of the Santorini volcano. This tree-ring growth anomaly is now directly dated ~1681–1673 BCE (68.2% highest posterior density range), ~20

  18. A Revised Holocene History of Lake Kivu, East Africa

    NASA Astrophysics Data System (ADS)

    Votava, J. E.; Johnson, T. C.; Hecky, R. E.

    2013-12-01

    The great lakes of the East African Rift valley are a vast chain of lakes formed in a region of active tectonics. These large, deep lakes are relatively old and many (e.g. Tanganyika, Malawi, and Turkana) have greatly influenced our understanding of terrestrial, tropical East African paleoclimate. Lake Kivu (max depth, 485m) sits at the heart of these rift lakes, north of Lake Tanganyika between the Democratic Republic of the Congo and Rwanda (roughly 250 km west of Lake Victoria). At over 1,400 meters in elevation, this 2,060 km2 mesotrophic lake has a complex stratification regime imposed by hydrothermal springs and deep waters supersaturated at STP in CO2 and CH4 gasses. The active Virunga Volcanoes to the north of the lake supply heated, high-salinity waters below 280 meters water depth maintaining the modern crenogenic meromixis. Based on detailed studies of diatom assemblages and bulk sedimentology, previous workers have suggested this hydrothermal activity began roughly 5,000 years BP. Unfortunately, dating and stratigraphic correlations of these original cores from the 1970 Woods Hole Oceanographic Institution's expedition have been problematic. Here we offer an improved chronology and new carbonate analyses from cores recovered in 2012 and 2013. Our AMS radiocarbon ages come from six terrigeneous macrofossils spanning the last 9,100 years (cal BP). These ages suggest a rather high sedimentation rate on the order of 70cm/kyr, and hence, our 8 m-long core provides us with a high-resolution lake history for the past 10,000 years. Most notable over the past 5,000 years in the lake history is the repeated onset and cessation of carbonate deposition, punctuated by organic-rich intervals. Earlier studies of the Woods Hole cores placed the onset of carbonate deposition at ca. 11,000 years BP suggesting changes in lake hydrology (i.e. closed to open), while the abrupt cessation of carbonate was dated at ca. 5,000 years BP and attributed to the beginning of

  19. 76 FR 75795 - Revisions to the California State Implementation Plan, Placer County Air Pollution Control District

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-05

    ... AGENCY 40 CFR Part 52 Revisions to the California State Implementation Plan, Placer County Air Pollution... taking direct final action to approve revisions to the Placer County Air Pollution Control District... earlier version of PCAPCD Rule 218 into the SIP on July 18, 1996 (61 FR 37390). The PCAPCD...

  20. The seismic-stratigraphic record of lake-level fluctuations in Lake Challa: Hydrological stability and change in equatorial East Africa over the last 140 kyr

    NASA Astrophysics Data System (ADS)

    Moernaut, J.; Verschuren, D.; Charlet, F.; Kristen, I.; Fagot, M.; De Batist, M.

    2010-02-01

    Seismic-reflection data from crater lake Challa (Mt. Kilimanjaro, equatorial East Africa) reveal a ˜ 210-m thick sedimentary infill containing distinct seismic-stratigraphic signatures of late-Quaternary lake-level fluctuations. Extrapolation of a well-constrained age model on the cored upper part of the sequence suggests that these lake-level fluctuations represent a detailed and continuous record of moisture-balance variation in equatorial East Africa over the last 140 kyr. This record indicates that the most severe aridity occurred during peak Penultimate glaciation immediately before ˜ 128 kyr BP (coeval with Heinrich event 11) and during a Last Interglacial 'megadrought' period between ˜ 114 and ˜ 97 kyr BP; in comparison, Last Glacial Maximum (LGM) aridity was modest. It was preceded by ˜ 75 000 years of relatively stable and moist climate conditions interrupted by eleven short-lived dry spells, five of which match the timing of Heinrich events 2 to 6. Climate history near the East African equator reflects variation in the precessional forcing of monsoon rainfall modulated by orbital eccentricity, but precession-driven moisture fluctuations were less extreme than those observed in northern and southern tropical Africa. The near-continuous moist climate from ˜ 97 to 20.5 kyr BP recorded in the Lake Challa record contrasts with the trend towards greater aridity after ˜ 70 kyr BP documented in equatorial West Africa. This long period of moist glacial climate and a short, relatively modest LGM drought can be attributed to greater independence of western Indian Ocean monsoon dynamics from northern high-latitude glaciation than those in the tropical Atlantic Ocean. This rather persistent moist glacial climate regime may have helped maintain high biodiversity in the tropical forest ecosystems of the Eastern Arc mountains in Tanzania.

  1. Opticalman 1 and C, Rate Training Manual. [1972 Revised Edition].

    ERIC Educational Resources Information Center

    Naval Personnel Program Support Activity, Washington, DC.

    In this revised edition of an earlier publication (ED 070 574), fundamentals of optical instruments on board ships are presented in this rate training manual for regular navy and naval reserve personnel. The manual includes nine chapters: Introduction; Administration and Supervision; Nature of Light; Optical Alignment Instruments; Night Vision…

  2. Nuclear Power and the Environment: Questions and Answers. Revised.

    ERIC Educational Resources Information Center

    Campana, Robert J.; Langer, Sidney

    This publication is a complete revision of an earlier booklet brought on by the dramatic changes in the energy outlook of the United States that occurred in 1973 and 1974. The purpose of this document is to inform the public on the overall U.S. energy situation, in particular electricity generated from nuclear reactors and other sources. The…

  3. Earlier wine-grape ripening driven by climatic warming and drying and management practices

    NASA Astrophysics Data System (ADS)

    Webb, L. B.; Whetton, P. H.; Bhend, J.; Darbyshire, R.; Briggs, P. R.; Barlow, E. W. R.

    2012-04-01

    Trends in phenological phases associated with climate change are widely reported--yet attribution remains rare. Attribution research in biological systems is critical in assisting stakeholders to develop adaptation strategies, particularly if human factors may be exacerbating impacts. Detailed, quantified attribution helps to effectively target adaptation strategies, and counters recent tendencies to overattribute phenological trends to climate shifts. Wine grapes have been ripening earlier in Australia in recent years, often with undesirable impacts. Attribution analysis of detected trends in wine-grape maturity, using time series of up to 64 years in duration, indicates that two climate variables--warming and declines in soil water content--are driving a major portion of this ripening trend. Crop-yield reductions and evolving management practices have probably also contributed to earlier ripening. Potential adaptation options are identified, as some drivers of the trend to earlier maturity can be manipulated through directed management initiatives, such as managing soil moisture and crop yield.

  4. Later endogenous circadian temperature nadir relative to an earlier wake time in older people

    NASA Technical Reports Server (NTRS)

    Duffy, J. F.; Dijk, D. J.; Klerman, E. B.; Czeisler, C. A.

    1998-01-01

    The contribution of the circadian timing system to the age-related advance of sleep-wake timing was investigated in two experiments. In a constant routine protocol, we found that the average wake time and endogenous circadian phase of 44 older subjects were earlier than that of 101 young men. However, the earlier circadian phase of the older subjects actually occurred later relative to their habitual wake time than it did in young men. These results indicate that an age-related advance of circadian phase cannot fully account for the high prevalence of early morning awakening in healthy older people. In a second study, 13 older subjects and 10 young men were scheduled to a 28-h day, such that they were scheduled to sleep at many circadian phases. Self-reported awakening from scheduled sleep episodes and cognitive throughput during the second half of the wake episode varied markedly as a function of circadian phase in both groups. The rising phase of both rhythms was advanced in the older subjects, suggesting an age-related change in the circadian regulation of sleep-wake propensity. We hypothesize that under entrained conditions, these age-related changes in the relationship between circadian phase and wake time are likely associated with self-selected light exposure at an earlier circadian phase. This earlier exposure to light could account for the earlier clock hour to which the endogenous circadian pacemaker is entrained in older people and thereby further increase their propensity to awaken at an even earlier time.

  5. Benthic foraminiferal δ18O-Mg/Ca from the SE Nordic seas during the last 65 kyr

    NASA Astrophysics Data System (ADS)

    Ezat, M.; Rasmussen, T. L.; Groeneveld, J.

    2013-12-01

    Benthic foraminiferal δ18O-Mg/Ca from the SE Nordic seas during the last 65 kyr Mohamed M. Ezat1,2*, Tine L. Rasmussen1, Jeroen Groeneveld3 1 CAGE - Centre for Arctic Gas Hydrate, Environment and Climate, and Department of Geology, University of Tromsø, NO-9037 Tromsø, Norway. 2 Department of Geology, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt. 3 Department of Geosciences, University of Bremen, Klagenfurter Strasse, 28359, Bremen, Germany. * e-mail: mohamed.ezat@uit.no The climate during the last glacial period underwent rapid millennial-scale variability known as Dansgaard-Oeschger (DO) events of warm interstadials and cold stadials. DO events are manifested in marine and continental records in the circum-North Atlantic region and throughout the globe. Several studies suggest a crucial role of the Nordic seas in regulating the climate during the last glacial period. Previous studies from the Nordic seas revealed low benthic δ18O values during stadials and high values during interstadials. The causes of the depletions in benthic 18O during stadials are highly debated. Sinking of isotope depleted-brines formed due to sea ice production has previously been proposed. Another explanation has indicated warming of the intermediate water in the Nordic seas based on the finding of warm water benthic foraminiferal species during stadials. Here we present the first benthic foraminiferal Mg/Ca-based bottom water temperature (BWT) record from the Nordic seas that, along with other proxies, aims to resolve the hydrographic changes at intermediate water depth on DO timescale during the last 65 kyr. The results show pronounced and gradual BWT increases during all cold stadials followed by an abrupt drop to modern-like BWT at interstadials onsets. The increase in BWT, caused by the subsurface inflow of warm Atlantic intermediate water, substantially contributed to the halocline collapse and onset of interstadial conditions throughout complex ocean-sea ice

  6. Catastrophic flank collapses and slumping in Pico Island during the last 130 kyr (Pico-Faial ridge, Azores Triple Junction)

    NASA Astrophysics Data System (ADS)

    Costa, A. C. G.; Hildenbrand, A.; Marques, F. O.; Sibrant, A. L. R.; Santos de Campos, A.

    2015-09-01

    The Pico Island constitutes the easternmost sub-aerial domain of a steep WNW-ESE volcanic ridge, which has developed within the Nubia-Eurasia diffuse plate boundary (Azores Triple Junction). The island comprises three volcanic systems, from older to younger: the Topo Volcano, the Fissural System, and the Pico Stratovolcano. From a high-resolution Digital Elevation Model (10 m), and new bathymetric, stratigraphic, structural, and high-precision K-Ar data, we reconstruct the main successive stages of growth and partial destruction of the island over the last 200 kyr. We especially concentrate on the central sector of the island, which has recorded gradual movements through slumping and catastrophic flank collapses since ca. 130 kyr. The remmants of the Topo Volcano are partly exposed on Pico's SE flank, and are here dated between 186 ± 5 and 115 ± 4 ka. Topo was significantly destroyed by N- and S-directed large-scale flank collapses between ca. 125 and 70 ka. On Pico's N flank, collapse seems to have removed all the unstable material, but in the S the collapse structure is composite, including a major flank collapse and a remnant slump complex that is still active. A first episode of deformation occurred between ca. 125 and 115 ka along the master fault of the slump. Between ca. 115 and 69 ka, most of the unstable material was removed by a major flank collapse, leaving behind a still considerable volume of unstable material that comprises the active slump. This first collapse was catastrophic and generated a large debris deposit recognized on the high-resolution bathymetry, with a minimum run-out of ca. 17 km. The scar was partially filled by volcanic products erupted from volcanic cones developed within the slump depression, and possibly also from the early WNW-ESE Fissural System. Subsequent deformation in the slump area affected in part the filling units, leading to the individualization of secondary curved faults. Younger volcanic products have gradually

  7. Quantitative woody cover reconstructions from eastern continental Asia of the last 22 kyr reveal strong regional peculiarities

    NASA Astrophysics Data System (ADS)

    Tian, Fang; Cao, Xianyong; Dallmeyer, Anne; Ni, Jian; Zhao, Yan; Wang, Yongbo; Herzschuh, Ulrike

    2016-04-01

    We present a calibration-set based on modern pollen and satellite-based Advanced Very High Resolution Radiometer (AVHRR) observations of woody cover (including needleleaved, broadleaved and total tree cover) in eastern continental Asia, which shows good performance under cross-validation with the modern analogue technique (all the coefficients of determination between observed and predicted values are greater than 0.65). The calibration-set is used to reconstruct woody cover from a taxonomically harmonized and temporally standardized fossil pollen dataset (including 274 cores) with 500-year resolution over the last 22 kyr. The spatial range of forest has not noticeably changed in eastern continental Asia during the last 22 kyr, although woody cover has, especially at the margin of the eastern Tibetan Plateau and in the forest-steppe transition area of north-central China. Vegetation was sparse during the LGM in the present forested regions, but woody cover increased markedly at the beginning of the Bølling/Allerød period (B/A; ca. 14.5 ka BP) and again at the beginning of the Holocene (ca. 11.5 ka BP), and is related to the enhanced strength of the East Asian Summer Monsoon. Forest flourished in the mid-Holocene (ca. 8 ka BP) possibly due to favourable climatic conditions. In contrast, cover was stable in southern China (high cover) and arid central Asia (very low cover) throughout the investigated period. Forest cover increased in the north-eastern part of China during the Holocene. Comparisons of these regional pollen-based results with simulated forest cover from runs of a global climate model (for 9, 6 and 0 ka BP (ECHAM5/JSBACH ∼1.125° spatial resolution)) reveal many similarities in temporal change. The Holocene woody cover history of eastern continental Asia is different from that of other regions, likely controlled by different climatic variables, i.e. moisture in eastern continental Asia; temperature in northern Eurasia and North America.

  8. Multiproxy Records of Indo-Pacific Climate and Environmental Change from Lake Towuti, Indonesia, Since 60 Kyr BP

    NASA Astrophysics Data System (ADS)

    Russell, J. M.; Vogel, H.; Bijaksana, S.; Konecky, B. L.; Wicaksono, S. A.; Costa, K.; Wattrus, N. J.; Melles, M.

    2014-12-01

    Lake Towuti is a large tectonic lake in central Sulawesi, Indonesia that provides a unique opportunity to reconstruct climate and terrestrial environments in the heart of the Indo-Pacific warm pool. Long-term climate variations in this region are governed by a complex interplay between the Australasian monsoons and the ENSO system forced by changing insolation, sea level, ice sheets, and greenhouse gas concentrations. Existing reconstructions suggest heterogeneous responses of Indonesian climate to these forcings, highlighting the need for new long records of regional hydrology. We have developed multiproxy datasets from Lake Towuti and nearby lakes that provide continuous, detailed, and reproducible paleoenvironmental records spanning the past 60 kyr BP. Elemental tracers of terrestrial runoff and compound-specific stable isotope records of vegetation show that wet conditions and rainforest ecosystems persisted during Marine Isotope Stage 3 and the Holocene, and were interrupted by severe drying between 33 and 15 kyr BP when high-latitude ice sheets expanded and global temperatures cooled. This chronology of change implies that central Indonesian hydroclimate varies strongly in response to high-latitude climate forcing. New vegetation records from nearby lakes confirm these findings, but suggest the amplitude of glacial-interglacial changes in vegetation were weaker at high altitude, with important implications for the heterogeneity among Indonesian climate reconstructions. New lithologic and trace element records from Lake Towuti further document the significance of climate changes at the MIS3, 2, and 1 boundaries to Lake Towuti's paleolimnology, heat budget, and seasonal mixing. High-resolution seismic reflection data from Lake Towuti constrain the maximum depth of lake level lowstands during MIS2. Hydrological modeling suggests that precipitation was reduced by at least 50% at that time, an amplitude at or above the upper limits of precipitation changes

  9. Multiproxy approach revealing climate and cultural changes during the last 26kyrs in south-central Chile

    NASA Astrophysics Data System (ADS)

    Abarzua, Ana M.; Jarpa, Leonora; Martel, Alejandra; Vega, Rodrigo; Pino, Mario

    2010-05-01

    Multiproxy approach from Purén Lumaco Valley (38°S) describes the paleonvironmental history during the Last Maximum Glacial (LGM) in south-central Chile. Three sediment cores and severals AMS 14C dates were used to perform a complete pollen, diatoms, chironomids, and sedimentological records demonstrating the existence of a large and non profundal paleolake, between 25 and 20kyr BP. Some of these evidence are laminated silty-clay sediments (lacustrine rhythmites), associated with the presence of siderite mineral (FeCO3), besides biological proxies like Fragilaria construens and Stauroforma inermes (planctonic diatoms), and Dicrotendipes sp. and Tanytarsini tribe (littoral chironomids). The pollen ensemble reveals the first glacial refuge of Araucaria araucana forests in the low lands during the LGM. The lake was drained abruptly into a swamp/bog at 12kyr BP and colonized by Myrtaceae wet forest. This evidence suggest the dry/warm climate period of early Holocene in south-central Chile. Later, the sediments indicate variable lacustrine levels, and increase of charcoal particles, associated to current climatic conditions. The pollen spectrum dominated by Myrtaceae and Nothofagus contrasts with a strongly disturb current landscape. Actually, Purén-Lumaco valley constitutes a complex peat-bog system dominated by exotic grasses and forest species (Tritricum aestivum, Pinus radiata and Eucalyptus spp.). Some archaeological antecedents in the area document the human development at ca. 7yrs BP. The greatest archaeological characteristic present in the valley is the kuel, a Mapuche earth accumulation. The presence and extension of almost 300 kuel in the valley reflect the social/economic development, and partly explains why the region was the major resistance area for Spanish colonizer during XVI-XVII centuries. Also the archaeological findings reveal the presence of maize pollen (Zea mays) within their food consumption. The influence of climate and human impact in

  10. Plant wax δD values record changing Eastern Mediterranean atmospheric circulation patterns during the 8.2 kyr B.P. climatic event

    NASA Astrophysics Data System (ADS)

    Schemmel, Fabian; Niedermeyer, Eva M.; Schwab, Valérie F.; Gleixner, Gerd; Pross, Jörg; Mulch, Andreas

    2016-02-01

    Throughout the Holocene, the climate of the Mediterranean region has been strongly influenced by variability in the atmospheric circulation of the high and low latitudes. A prominent example for such Holocene climate perturbations is the '8.2 kyr B.P. climatic event'. Reorganization of Northern Hemisphere atmospheric circulation patterns resulted in variations of temperature and precipitation distribution across the Mediterranean. The effects of changing high- and low-latitude atmospheric circulation on Mediterranean climate in relation to the 8.2 kyr B.P. climatic event are, however, not well understood. Here we present a high-resolution record of stable hydrogen isotope composition of plant-wax n-alkanes (δDwax) across the 8.2 kyr B.P. climatic event from the Tenaghi Philippon peat deposit (NE Greece) in order to characterize patterns of precipitation and changes in atmospheric circulation in the Eastern Mediterranean region. Our record reveals pronounced changes in δDwax that correlate closely with previously published palynological data. A long-term decline in δDwax values characterizes the lower part of the section. The 8.2 kyr B.P. climatic event itself is connected to two distinct positive δDwax excursions: a minor shift in δDwax around 8.2 kyr B.P. and a major shift in δDwax between ca. 8.1 and 8.0 kyr B.P.. The upper part of the section shows a progressive trend towards higher δDwax values. We link shifts in δDwax to changes in Mediterranean air mass trajectories supplying precipitation to NE Greece caused by variations in the relative contributions of northerly-derived, D-depleted moisture and southerly-derived, D-enriched moisture. Possible control mechanisms for alternating air mass trajectories include changes in the influence of the Siberian High and differences in the influence of the African and Asian monsoon circulation on anticyclonic conditions in the Mediterranean region as well as regional inflow of moist air masses from the Aegean Sea.

  11. Freshwater input into the Gulf of Mexico Prior to the 8.2 cal kyr BP Cool Event in Greenland Ice Core Records

    NASA Astrophysics Data System (ADS)

    Lodico, J. M.; Flower, B. P.; Quinn, T. M.

    2004-12-01

    The most prominent event recorded in Greenland ice core records over the past 10 calendar kiloyears before present (cal kyr BP) is an abrupt cooling at 8.2 cal kyr BP, which lasted for 300-400 yrs. It has been proposed that this climatic event was caused by a weakening of the thermohaline circulation in the North Atlantic forced by a vast outflow of freshwater through the Hudson Strait from glacial lakes Agassiz and Ojibway. Sediment core MD02-2550 from Orca Basin located in the northern Gulf of Mexico (GOM) provides an early Holocene record (10 to 7 cal kyr BP) of GOM climate changes, input from the Mississippi River system and adjacent continental areas. Paired analysis of Mg/Ca, a proxy of sea surface temperatures (SSTs), and \\delta18O on the planktonic foraminifera { \\it Globigerinoides ruber } (white variety; 250 -350 μ m) sampled at 0.5 cm (providing ˜20 year resolution), indicate a large isotopic excursion of ˜ -1 ‰ \\delta18O seawater from 8.5 to 8.4 cal kyr BP, coincident with the drainage of glacial lakes Agassiz and Ojibway at 8.47 cal kyr BP. We consider three possible sources for this freshwater pulse: freshwater input from glacial lakes, meltwater input from the drainage of the Laurentide Ice Sheet's final dome, and/or increased precipitation in North American drainage basins. Mg/Ca-SSTs show minimal mean change across the freshwater interval and an average of ˜28 ° C from 7 to 10 cal kyr BP, which is within the current mean SSTs for GOM ( ˜28 ° C). Mg/Ca-SST and \\delta18O seawater time series contain concentrations of variance near 500, 220, 146, and 60 years, significant at the 90 % confidence level, indicating possible sensitivity to solar variations. Ongoing faunal assemblage work will provide additional assessment for SST, sea surface salinity (SSS) and nutrient changes during the early Holocene in the GOM.

  12. Genetic change for earlier migration timing in a pink salmon population.

    PubMed

    Kovach, Ryan P; Gharrett, Anthony J; Tallmon, David A

    2012-09-22

    To predict how climate change will influence populations, it is necessary to understand the mechanisms, particularly microevolution and phenotypic plasticity, that allow populations to persist in novel environmental conditions. Although evidence for climate-induced phenotypic change in populations is widespread, evidence documenting that these phenotypic changes are due to microevolution is exceedingly rare. In this study, we use 32 years of genetic data (17 complete generations) to determine whether there has been a genetic change towards earlier migration timing in a population of pink salmon that shows phenotypic change; average migration time occurs nearly two weeks earlier than it did 40 years ago. Experimental genetic data support the hypothesis that there has been directional selection for earlier migration timing, resulting in a substantial decrease in the late-migrating phenotype (from more than 30% to less than 10% of the total abundance). From 1983 to 2011, there was a significant decrease--over threefold--in the frequency of a genetic marker for late-migration timing, but there were minimal changes in allele frequencies at other neutral loci. These results demonstrate that there has been rapid microevolution for earlier migration timing in this population. Circadian rhythm genes, however, did not show any evidence for selective changes from 1993 to 2009. PMID:22787027

  13. Algorithms for Developing Test Questions from Sentences in Instructional Materials: An Extension of an Earlier Study.

    ERIC Educational Resources Information Center

    Roid, Gale H.; And Others

    An earlier study was extended and replicated to examine the feasibility of generating multiple-choice test questions by transforming sentences from prose instructional material. In the first study, a computer-based algorithm was used to analyze prose subject matter and to identify high-information words. Sentences containing selected words were…

  14. Left ventricular pseudoaneurysm found after mitral valve replacement performed 30 years earlier.

    PubMed

    Castilla, Elena; Gato, Manuel; Ruiz, José Ramón

    2010-03-01

    Pseudoaneurysm of the left ventricle (LV) is a rare cardiac disease that occurs after myocardial infarction or cardiac surgery. Because patients frequently present with nonspecific symptoms, a high index of suspicion is needed to make the diagnosis. This report describes an unusual case demonstrating a large LV pseudoaneurysm after mitral valve replacement performed 30 years earlier. PMID:20197588

  15. Children Learning to Read Later Catch up to Children Reading Earlier

    ERIC Educational Resources Information Center

    Suggate, Sebastian P.; Schaughency, Elizabeth A.; Reese, Elaine

    2013-01-01

    Two studies from English-speaking samples investigated the methodologically difficult question of whether the later reading achievement of children learning to read earlier or later differs. Children (n = 287) from predominantly state-funded schools were selected and they differed in whether the reading instruction age (RIA) was either five or…

  16. Sea ice and millennial-scale climate variability in the Nordic seas 90 kyr ago to present

    PubMed Central

    Hoff, Ulrike; Rasmussen, Tine L.; Stein, Ruediger; Ezat, Mohamed M.; Fahl, Kirsten

    2016-01-01

    In the light of rapidly diminishing sea ice cover in the Arctic during the present atmospheric warming, it is imperative to study the distribution of sea ice in the past in relation to rapid climate change. Here we focus on glacial millennial-scale climatic events (Dansgaard/Oeschger events) using the sea ice proxy IP25 in combination with phytoplankton proxy data and quantification of diatom species in a record from the southeast Norwegian Sea. We demonstrate that expansion and retreat of sea ice varies consistently in pace with the rapid climate changes 90 kyr ago to present. Sea ice retreats abruptly at the start of warm interstadials, but spreads rapidly during cooling phases of the interstadials and becomes near perennial and perennial during cold stadials and Heinrich events, respectively. Low-salinity surface water and the sea ice edge spreads to the Greenland–Scotland Ridge, and during the largest Heinrich events, probably far into the Atlantic Ocean. PMID:27456826

  17. Sea ice and millennial-scale climate variability in the Nordic seas 90 kyr ago to present.

    PubMed

    Hoff, Ulrike; Rasmussen, Tine L; Stein, Ruediger; Ezat, Mohamed M; Fahl, Kirsten

    2016-01-01

    In the light of rapidly diminishing sea ice cover in the Arctic during the present atmospheric warming, it is imperative to study the distribution of sea ice in the past in relation to rapid climate change. Here we focus on glacial millennial-scale climatic events (Dansgaard/Oeschger events) using the sea ice proxy IP25 in combination with phytoplankton proxy data and quantification of diatom species in a record from the southeast Norwegian Sea. We demonstrate that expansion and retreat of sea ice varies consistently in pace with the rapid climate changes 90 kyr ago to present. Sea ice retreats abruptly at the start of warm interstadials, but spreads rapidly during cooling phases of the interstadials and becomes near perennial and perennial during cold stadials and Heinrich events, respectively. Low-salinity surface water and the sea ice edge spreads to the Greenland-Scotland Ridge, and during the largest Heinrich events, probably far into the Atlantic Ocean. PMID:27456826

  18. Thermal isolation of Campbell Plateau, New Zealand, by the Antarctic Circumpolar Current over the past 130 kyr

    NASA Astrophysics Data System (ADS)

    Neil, Helen L.; Carter, Lionel; Morris, Michele Y.

    2004-12-01

    Campbell Plateau occupies a key position in the southwest Pacific sector of the Southern Ocean. The plateau confines and steers the Antarctic Circumpolar Current (ACC) along its flanks, isolating the Subantarctic plateau from cold polar waters. Oxygen and carbon isotope records from Campbell Plateau cores provide new records of water mass stratification for the past 130 kyr. During glacial climes, strengthening of the Subantarctic Front (SAF) caused waters over the plateau flanks to be deeply mixed and ˜3°C cooler. Waters of the plateau interior remained stratified and isolated from the cold southern waters. In the west, waters cooled markedly (˜4°C) owing to reduced entrainment of Tasman Sea water. Marked cooling also occurred north of Campbell Plateau under increased entrainment of polar water by a branch of the SAF. The ACC remained along the flanks of Campbell Plateau during the last interglacial, when interior waters were stratified and warmer by ˜1°C than now.

  19. Variability of Indian summer monsoon over the past 252 kyr revealed by stalagmite record in Southwest China

    NASA Astrophysics Data System (ADS)

    Cai, Y.; Fung, I. Y.; Edwards, R.; An, Z.; Cheng, H.; Lee, J.

    2013-12-01

    Multiple proxies obtained from Arabian Sea sediments have revealed the variability of Indian summer Monsoon (ISM) on time scale of 100-105 years. These proxies mainly capture summertime winds over the Arabian Sea and our understanding of Indian summer monsoon precipitation variability; and the relationship between paleo-ISM and paleo East Asia summer monsoon (EASM) lacks precise articulation, however, due to the scarcity of high-resolution precipitation records spanning a glacial-interglacial cycle. Here, we present an absolutely-dated oxygen isotope record from stalagmites in Xiaobailong (XBL) cave, southwestern China, that documents the variability in local precipitation and the ISM for the past 252,000 years. This record is dominated by 23-kyr precessional cycles punctuated by prominent millennial-scale oscillations that are synchronous with Heinrich events in the North Atlantic. It also shows clear glacial-interglacial variations that are consistent with marine and other terrestrial proxies. The distinct glacial-interglacial range in XBL δ18O is larger than that of speleothem records from eastern China. Corroborated with results from an isotope-enabled global climate model, we hypothesize that these dissimilarities may reflect the different responses of ISM and EASM to changes in global circulation and moisture source, in particular those caused by glacial-interglacial sea-land configuration changes as manifested by notable coastline shifts in the Western Pacific and Maritime Continent.

  20. The 8.2 kyr event recorded at high resolution by a speleothem from the Northern French Alps

    NASA Astrophysics Data System (ADS)

    Couchoud, Isabelle; Drysdale, Russell; Hellstrom, John; Perrette, Yves

    2016-04-01

    Continental records of Holocene climate variability in the Alps are scarce and they rarely document the "8.2 kyr event". Several reasons have been proposed: records do not have sufficient resolution, are not precisely dated or the proxies are not sufficiently sensitive to climate variations associated with this event. The European records of adequate resolution generally allow the identification of an anomaly but its characterisation is unclear: it seems that the event has triggered significant impacts only for a few decades and mainly expressed in winter (whereas most archives are more sensitive to summer conditions). Thus, the detailed characterisation of the impacts of this event requires records with sub-annual resolution and preferably sensitive to winter conditions. Here we present a multi-proxy, high-resolution analysis of this event, as recorded by a stalagmite of the Bauges massif (Northern French Alps), at ~1400 m altitude. Comparison of these results with other regional and distant data allows for a discussion about climatic impacts and teleconnections at this time.

  1. The bioavailable iron in NEEM ice core related to Asian dust records over the past 110 kyr

    NASA Astrophysics Data System (ADS)

    Xiao, Cunde

    2016-04-01

    The mineral dust can indirectly affect climate by supplying iron and other essential bioavailable elements into ocean. In this study, we present dissolved iron (DFe) and total dissolved iron (TDFe) concentrations in NEEM ice core over the past 110 kyr B.P. The concentrations of bioavailable reactive element Fe have good positive correlation with the concentrations of dust and Ca2+ in NEEM ice core, while show significantly negative relationship with δ18O and CO2 concentration. The ratios of DFe/TDFe are higher in warm periods (Holocene and last interglacial) than in cold period (LGM), indicating the iron-biological pump effect is more significant in warm periods than that in cold periods, this result may provide a new insight for reevaluating the iron hypothesis over glacial/interglacial periods. Our study also shows that the iron flux changes between NEEM ice core and Asian loess records are good consistent with the northern Hemisphere summer insolation. These results emphasize that the variability of Fe flux is most likely driven by solar radiation and dust in northern hemisphere.

  2. A pervasive link between Antarctic ice core and subarctic Pacific sediment records over the past 800 kyrs

    NASA Astrophysics Data System (ADS)

    Jaccard, S. L.; Galbraith, E. D.; Sigman, D. M.; Haug, G. H.

    2010-01-01

    Recently developed XRF core-scanning methods permit paleoceanographic reconstructions on timescales similar to those of ice-core records. We have investigated the distribution of biogenic barium (Ba/Al), opal and carbonate (Ca/Al) in a sediment core retrieved from the abyssal subarctic Pacific (ODP 882, 50°N, 167°E, 3244 m) over an interval that spans the full length of the EPICA Dome C (EDC) ice-core record. Ba/Al and biogenic opal show a strong resemblance to the EDC δD and CO 2, with generally high concentrations during interglacials and lower values during ice ages of the past 800 kyrs. The sedimentary Ba/Al and biogenic opal are most easily interpreted as indicating a reduced sinking flux of organic matter from the surface ocean during cold periods. The Ba/Al maxima during peak interglacials are accompanied by transient Ca/Al peaks in these otherwise carbonate-devoid sediments, which are best explained by a deepening of the calcite lysocline, presumably due to reduced storage of respired CO 2 in the deep North Pacific. For most of the "luke-warm" interglacials noted between 420 and 750 ka in EDC, the Ba/Al peaks in ODP 882 are also lower, further strengthening the evidence for a simple physical link between global climate and the biogeochemistry of the subarctic Pacific.

  3. A paleomagnetic and relative paleointensity record from the Argentine Basin (western South Atlantic Ocean) for the last ~125 kyrs

    NASA Astrophysics Data System (ADS)

    Heil, C. W., Jr.; Stoner, J. S.; St-Onge, G.; King, J. W.

    2015-12-01

    The paucity of paleomagnetic records from the western South Atlantic Ocean presents a significant gap in our understanding of the spatial variations in geomagnetic field dynamics as they relate to the occurrence of geomagnetic excursions and changes in field strength. As such, high quality records from this region can help build upon Holocene observations and extend the geographic and temporal data coverage for spherical harmonic models. To that end, we present paleomagnetic directional (inclination) and strength (relative paleointensity) records from two cores from the Argentine Basin (RC11-49 and RC16-88). Although the cores were collected more than 40 years ago, the sediments appear to hold a stable remanence and reliable magnetic directions, as evidenced by their reproducibility between the two cores that are separated by ~25 km. The records show evidence of 4 excursional features in the uppermost 16-m of the sediments from the basin. A comparison of the relative paleointensity records from these cores to the South Atlantic Paleointensity Stack (SAPIS) (Stoner et al., 2002) and the relative paleointensity record from ODP Site 1089 (Stoner et al., 2003) indicate that the sediments reliably record relative changes in geomagnetic field intensity and suggests that the longest record (RC11-49) spans the last ~125 kyrs. Our results indicate that the sediments of the Argentine Basin are an important sedimentary archive of geomagnetic field behavior and strength at least through the Holocene and Late Pleistocene and highlight the need for further studies of cores within the basin.

  4. Export production in the subarctic North Pacific over the last 800 kyrs: No evidence for iron fertilization?

    USGS Publications Warehouse

    Kienast, S.S.; Hendy, I.L.; Crusius, J.; Pedersen, Thomas F.; Calvert, S.E.

    2004-01-01

    The subarctic North Pacific is a high nitrate-low chlorophyll (HNLC) region, where phytoplankton growth rates, especially those of diatoms, are enhanced when micro-nutrient Fe is added. Accordingly, it has been suggested that glacial Fe-laden dust might have increased primary production in this region. This paper reviews published palaeoceanographic records of export production over the last 800 kyrs from the open North Pacific (north of ???35??N). We find different patterns of export production change over time in the various domains of the North Pacific (NW and NE subarctic gyres, the marginal seas and the transition zone). However, there is no compelling evidence for an overall increase in productivity during glacials in the subarctic region, challenging the paradigm that dust-born Fe fertilization of this region has contributed to the glacial draw down of atmospheric CO2. Potential reasons for the lack of increased glacial export production include the possibility that Fe-fertilization rapidly drives the ecosystem towards limitation by another nutrient. This effect would have been exacerbated by an even more stable mixed layer compared to today. ?? The Oceanographic Society of Japan.

  5. Palaeomagnetic intensities from 14C-dated lava flows on the Big Island, Hawaii: 0-21 kyr

    USGS Publications Warehouse

    Pressling, Nicola; Laj, Carlo; Kissel, Catherie; Champion, Duane E.; Gubbins, David

    2006-01-01

    Thellier–Thellier experiments were carried out on 216 lava samples collected by the USGS on the Big Island. 35 individual flows from the Kilauea, Mauna Loa and Hualalai volcanoes are represented and independent radiocarbon dating of the flows yields absolute ages ranging from 290 to 20,240 yrs old. The palaeomagnetic analysis was carried out at the Laboratoire des Sciences du Climat et de l'Environnement in Gif-sur-Yvette, France, in two custom built, large capacity furnaces that have been specifically designed to minimise oxidation. The temperature steps were adapted to accommodate the characteristic loss of magnetisation at low temperatures seen in the Curie balance results and the use of half-size samples allowed secondary experiments to be carried out where necessary. The strict PICRIT-03 selection criteria were rigorously applied to the data and a high success rate of 53% has been achieved on a sample level. The flow averaged results almost double the existing 14C-dated palaeointensity dataset for this time window and confirm a period of high intensity over the past 4 kyr preceded by a period in which the dipole moment was weaker. However, the values attained in this study are on average higher than previously published data; reliability of these values is discussed.

  6. A Coral Based Reconstruction of Atmospheric Δ14C through the Mystery Interval (17.5 to 14.5 kyr BP)

    NASA Astrophysics Data System (ADS)

    Mortlock, R. A.; Abdul, N. A.; Wright, J. D.; Fairbanks, R. G.; Cao, L.

    2011-12-01

    Reconstructions of atmospheric Δ14C from various archives (speleothems, planktic foraminifera, surface corals) record a ~ 190 per mil (%) decrease in Δ14C during the Mystery Interval (17.5 to 14.5 kyr BP). It has been suggested that the decrease results from the injection of 14C depleted waters during the deglacial. Supporting evidence comes from benthic forams in sediment cores off Baja, CA that record a 300% decrease in the 14C content of intermediate waters at the same time ice core records display an increase in atmospheric CO2. Records of opal burial in Southern Ocean sediments suggest increased upwelling (and release of 14C depleted CO2 to the atmosphere) during the Mystery Interval. We have updated our previously published record of atmospheric Δ14C with an additional 60-paired radiocarbon and U-series dated surface corals. A unique advantage to using the fossil coral archive is that both radiocarbon and calendar ages can be obtained from the same sample, whereas atmospheric 14C reconstructions generated from deep sea core microfossils require assigned calendar ages which are based on proxies correlated to ice cores and are subject to proxy interpretations, correlation errors, and uncertainties in ice core chronologies. Unfortunately small inaccuracies in the estimated calendar ages lead to large Δ14C errors. The updated coral record adds considerable coverage to both the Mystery Interval (previously constrained by coral data only at the boundaries in INTCAL04 and 09), and for the time period 26 to 18 kyr BP. Our record permits a better estimate as to the timing, duration, and magnitude of the decrease in Δ14C during the Mystery Interval. We observe a break in the declining 27 to 21 kyr BP trend of Δ14C at about 20 kyr BP. From 20 to 18.5 kyr BP Δ14C increases by about 100% to a maximum value of about 430%. Δ14C decreases to 300% by about 17 kyr BP at which time the long term declining trend in Δ14C is re-established and continues throughout the

  7. Late Quaternary vegetation and environments in the Verkhoyansk Mountains region (NE Asia) reconstructed from a 50-kyr fossil pollen record from Lake Billyakh

    NASA Astrophysics Data System (ADS)

    Müller, Stefanie; Tarasov, Pavel E.; Andreev, Andrei A.; Tütken, Thomas; Gartz, Steffi; Diekmann, Bernhard

    2010-08-01

    Here we present a detailed radiocarbon-dated 936 cm long pollen record from Lake Billyakh (65°17'N, 126°47'E; 340 m a.s.l.) situated in the western part of the Verkhoyansk Mountains, about 140 km south of the Arctic Circle. A set of 53 surface pollen samples representing tundra, cold deciduous forest and taiga was collected in northern and central Yakutia communities to verify the accuracy of the quantitative biome reconstruction method and to obtain a more precise attribution of the identified pollen taxa to the main regional biomes. The adjusted method is then applied to the pollen record from Lake Billyakh to gain a reconstruction of vegetation and environments since about 50.7 kyr BP. The results of the pollen analysis and pollen-based biome reconstruction suggest that herbaceous tundra and steppe communities dominated the area from 50.7 to 13.5 kyr BP. Relatively low pollen concentrations and high percentages of herbaceous pollen taxa (mainly Cyperaceae, Poaceae and Artemisia) likely indicate a reduced vegetation cover and/or lower pollen production. On the other hand, extremely low percentages of drought-tolerant taxa, such as Chenopodiaceae and Ephedra, and the constant presence of various mesophyllous herbaceous ( Thalictrum, Rosaceae, Asteraceae) and shrubby taxa ( Betula sect. Nanae/Fruticosae, Duschekia fruticosa, Salix) in the pollen assemblages prevent an interpretation of the last glacial environments around Lake Billyakh as extremely arid. The lowest pollen percentages of woody taxa and the highest values of Artemisia pollen attest that the 31-15 kyr BP period as the driest and coldest interval of the entire record. A relative high content of taxa representing shrub tundra communities and the presence of larch pollen recorded prior to 31 kyr and after 13.5 kyr BP likely indicate interstadial climate amelioration associated with the middle and latest parts of the last glacial. An increase in pollen percentages of herbaceous taxa around 12 kyr BP

  8. Sediment Cd and Mo accumulation in the oxygen-minimum zone off western Baja California linked to global climate over the past 52 kyr

    USGS Publications Warehouse

    Dean, W.E.; Zheng, Yen; Ortiz, J.D.; VanGeen, A.

    2006-01-01

    Concentrations of organic carbon (orgC), cadmium (Cd), and molybdenum (Mo) were measured in two sediment cores raised from depths of 430 and 700 m within the oxygen-minimum zone (OMZ) off southern Baja California at a temporal resolution of e10.5 kyr over the past 52 kyr. These records are supplemented with diffuse spectral reflectance (DSR) measurements obtained on board ship soon after collection at a resolution of e10.05 kyr. In the core from 700 m depth, a component extracted from the DSR data and the three geochemical proxies generally vary in concert with each other and over a wide range (4-22% orgC; 1-40 mg/kg Cd; 5-120 mg/kg Mo). Intervals of increased orgC, Cd, and Mo accumulation generally correspond to warm periods recorded in the oxygen-isotopic composition of Greenland ice, with the exception of the Bolling/Allerod which is only weakly expressed off Baja California. Concentrations of the biogenic proxies are higher in the core from 430 m depth, but erratic sediment accumulation before 15 ka precludes dating of the older intervals that are laminated and contain elevated orgC, Cd, and Mo concentrations. The new data provide further evidence of an intimate teleconnection between global climate and the intensity of the OMZ and/or productivity along the western margin of North America. On the basis of a comparison with Cd and Mo records collected elsewhere in the region, we conclude that productivity may actually have varied off southern Baja California by no more than a factor of 2 over the past 52 kyr. Copyright 2006 by the American Geophysical Union.

  9. Age-depth model of the past 630 kyr for Lake Ohrid (FYROM/Albania) based on cyclostratigraphic analysis of downhole gamma ray data

    NASA Astrophysics Data System (ADS)

    Baumgarten, H.; Wonik, T.; Tanner, D. C.; Francke, A.; Wagner, B.; Zanchetta, G.; Sulpizio, R.; Giaccio, B.; Nomade, S.

    2015-12-01

    Gamma ray (GR) fluctuations and potassium (K) values from downhole logging data obtained in the sediments of Lake Ohrid from 0 to 240 m below lake floor (b.l.f). correlate with fluctuations in δ18O values from the global benthic isotope stack LR04 (Lisiecki and Raymo, 2005). GR and K values are considered a reliable proxy to depict glacial-interglacial cycles, with high clastic input during cold and/or drier periods and high carbonate precipitation during warm and/or humid periods at Lake Ohrid. Spectral analysis was applied to investigate the climate signal and evolution over the length of the borehole. Linking downhole logging data with orbital cycles was used to estimate sedimentation rates and the effect of compaction was compensated for. Sedimentation rates increase on average by 14 % after decompaction of the sediment layers and the mean sedimentation rates shift from 45 cm kyr-1 between 0 and 110 m to 30 cm kyr-1 from 110 to 240 m b.l.f. Tuning of minima and maxima of gamma ray and potassium values versus LR04 extrema, in combination with eight independent tephrostratigraphical tie points, allows establishing of a robust age model for the downhole logging data over the past 630 kyr.

  10. Compulsive Buying: Earlier Illicit Drug Use, Impulse Buying, Depression, and Adult ADHD Symptoms

    PubMed Central

    Brook, Judith S.; Zhang, Chenshu; Brook, David W.; Leukefeld, Carl G.

    2015-01-01

    This longitudinal study examined the association between psychosocial antecedents, including illicit drug use, and adult compulsive buying (CB) across a 29-year time period from mean age 14 to mean age 43. Participants originally came from a community-based random sample of residents in two upstate New York counties. Multivariate linear regression analysis was used to study the relationship between the participant’s earlier psychosocial antecedents and adult CB in the fifth decade of life. The results of the multivariate linear regression analyses showed that gender (female), earlier adult impulse buying (IB), depressive mood, illicit drug use, and concurrent ADHD symptoms were all significantly associated with adult CB at mean age 43. It is important that clinicians treating CB in adults should consider the role of drug use, symptoms of ADHD, IB, depression, and family factors in CB. PMID:26165963

  11. Compulsive buying: Earlier illicit drug use, impulse buying, depression, and adult ADHD symptoms.

    PubMed

    Brook, Judith S; Zhang, Chenshu; Brook, David W; Leukefeld, Carl G

    2015-08-30

    This longitudinal study examined the association between psychosocial antecedents, including illicit drug use, and adult compulsive buying (CB) across a 29-year time period from mean age 14 to mean age 43. Participants originally came from a community-based random sample of residents in two upstate New York counties. Multivariate linear regression analysis was used to study the relationship between the participant's earlier psychosocial antecedents and adult CB in the fifth decade of life. The results of the multivariate linear regression analyses showed that gender (female), earlier adult impulse buying (IB), depressive mood, illicit drug use, and concurrent ADHD symptoms were all significantly associated with adult CB at mean age 43. It is important that clinicians treating CB in adults should consider the role of drug use, symptoms of ADHD, IB, depression, and family factors in CB. PMID:26165963

  12. A vantage from space can detect earlier drought onset: an approach using relative humidity.

    PubMed

    Farahmand, Alireza; AghaKouchak, Amir; Teixeira, Joao

    2015-01-01

    Each year, droughts cause significant economic and agricultural losses across the world. The early warning and onset detection of drought is of particular importance for effective agriculture and water resource management. Previous studies show that the Standard Precipitation Index (SPI), a measure of precipitation deficit, detects drought onset earlier than other indicators. Here we show that satellite-based near surface air relative humidity data can further improve drought onset detection and early warning. This paper introduces the Standardized Relative Humidity Index (SRHI) based on the NASA Atmospheric Infrared Sounder (AIRS) observations. The results indicate that the SRHI typically detects the drought onset earlier than the SPI. While the AIRS mission was not originally designed for drought monitoring, we show that its relative humidity data offers a new and unique avenue for drought monitoring and early warning. We conclude that the early warning aspects of SRHI may have merit for integration into current drought monitoring systems. PMID:25711500

  13. A Vantage from Space Can Detect Earlier Drought Onset: An Approach Using Relative Humidity

    PubMed Central

    Farahmand, Alireza; AghaKouchak, Amir; Teixeira, Joao

    2015-01-01

    Each year, droughts cause significant economic and agricultural losses across the world. The early warning and onset detection of drought is of particular importance for effective agriculture and water resource management. Previous studies show that the Standard Precipitation Index (SPI), a measure of precipitation deficit, detects drought onset earlier than other indicators. Here we show that satellite-based near surface air relative humidity data can further improve drought onset detection and early warning. This paper introduces the Standardized Relative Humidity Index (SRHI) based on the NASA Atmospheric Infrared Sounder (AIRS) observations. The results indicate that the SRHI typically detects the drought onset earlier than the SPI. While the AIRS mission was not originally designed for drought monitoring, we show that its relative humidity data offers a new and unique avenue for drought monitoring and early warning. We conclude that the early warning aspects of SRHI may have merit for integration into current drought monitoring systems. PMID:25711500

  14. Observed shift towards earlier spring discharge in the main Alpine rivers.

    PubMed

    Zampieri, Matteo; Scoccimarro, Enrico; Gualdi, Silvio; Navarra, Antonio

    2015-01-15

    In this study, we analyse the observed long-term discharge time-series of the Rhine, the Danube, the Rhone and the Po rivers. These rivers are characterised by different seasonal cycles reflecting the diverse climates and morphologies of the Alpine basins. However, despite the intensive and varied water management adopted in the four basins, we found common features in the trend and low-frequency variability of the spring discharge timings. All the discharge time-series display a tendency towards earlier spring peaks of more than two weeks per century. These results can be explained in terms of snowmelt, total precipitation (i.e. the sum of snowfall and rainfall) and rainfall variability. The relative importance of these factors might be different in each basin. However, we show that the change of seasonality of total precipitation plays a major role in the earlier spring runoff over most of the Alps. PMID:25005239

  15. Peak tornado activity is occurring earlier in the heart of "Tornado Alley"

    NASA Astrophysics Data System (ADS)

    Long, John A.; Stoy, Paul C.

    2014-09-01

    Tornado frequency may increase as the factors that contribute to severe convection are altered by a changing climate. Attributing changes in tornado frequency to observed global climate change is complicated because observational effort has increased over time, but studies of the seasonal distribution of tornado activity may avoid sampling biases. We demonstrate that peak tornado activity has shifted 7 days earlier in the year over the past six decades in the central and southern US Great Plains, the area with the highest global incidence of tornado activity. Results are largely unrelated to large-scale climate oscillations, and observed climate trends cannot fully account for observations, which suggest that changes to regional climate dynamics should be further investigated. Tornado preparedness efforts at individual to national levels should be cognizant of the trend toward earlier peak tornado activity across the heart of "Tornado Alley".

  16. Major depression associated with earlier alcohol relapse in treated teens with AUD.

    PubMed

    Cornelius, Jack R; Maisto, Stephen A; Martin, Christopher S; Bukstein, Oscar G; Salloum, Ihsan M; Daley, Dennis C; Wood, D Scott; Clark, Duncan B

    2004-07-01

    This study evaluated whether the common comorbid diagnosis of major depressive disorder (MDD) is associated with an earlier relapse to alcohol use among adolescents with an alcohol use disorder (AUD). The study sample consisted of 116 adolescents between the ages of 14 and 18 with an AUD recruited from treatment facilities in the Pittsburgh area, 50 of whom demonstrated a current MDD. An extensive baseline interview was conducted, followed by monthly interviews of alcohol use conducted by telephone for the following year. Those with current comorbid MDD demonstrated a median survival time of only 19 days until the first drink, while those without MDD demonstrated a median survival time of 45 days, which was a significant difference (Kaplan-Meier survival analysis, Breslow Test Statistic=4.27, df=1, P=.039). These results suggest that the comorbid presence of MDD is associated with an earlier relapse to alcohol use among adolescents with an AUD. PMID:15219354

  17. Trends toward an earlier peak of the growing season in Northern Hemisphere mid-latitudes.

    PubMed

    Xu, Chongyang; Liu, Hongyan; Williams, A Park; Yin, Yi; Wu, Xiuchen

    2016-08-01

    Changes in peak photosynthesis timing (PPT) could substantially change the seasonality of the terrestrial carbon cycle. Spring PPT in dry regions has been documented for some individual plant species on a stand scale, but both the spatio-temporal pattern of shifting PPT on a continental scale and its determinants remain unclear. Here, we use satellite measurements of vegetation greenness to find that the majority of Northern Hemisphere, mid-latitude vegetated area experienced a trend toward earlier PPT during 1982-2012, with significant trends of an average of 0.61 day yr(-1) across 19.4% of areas. These shifts correspond to increased annual accumulation of growing degree days (GDD) due to warming and are most highly concentrated in the eastern United States and Europe. Earlier mean PPT is generally a trait common among areas with summer temperatures higher than 27.6 ± 2.9 °C, summer precipitation lower than 84.2 ± 41.5 mm, and fraction of cold season precipitation greater than 89.2 ± 1.5%. The trends toward earlier PPT discovered here have co-occurred with overall increases in vegetation greenness throughout the growing season, suggesting that summer drought is not a dominant driver of these trends. These results imply that continued warming may facilitate continued shifts toward earlier PPT and cause these trends to become more pervasive, with important implications for terrestrial carbon, water, nutrient, and energy budgets. PMID:26752300

  18. A Review of Quality of Life after Predictive Testing for and Earlier Identification of Neurodegenerative Diseases

    PubMed Central

    Paulsen, Jane S.; Nance, Martha; Kim, Ji-In; Carlozzi, Noelle E.; Panegyres, Peter K.; Erwin, Cheryl; Goh, Anita; McCusker, Elizabeth; Williams, Janet K.

    2013-01-01

    The past decade has witnessed an explosion of evidence suggesting that many neurodegenerative diseases can be detected years, if not decades, earlier than previously thought. To date, these scientific advances have not provoked any parallel translational or clinical improvements. There is an urgency to capitalize on this momentum so earlier detection of disease can be more readily translated into improved health-related quality of life for families at risk for, or suffering with, neurodegenerative diseases. In this review, we discuss health-related quality of life (HRQOL) measurement in neurodegenerative diseases and the importance of these “patient reported outcomes” for all clinical research. Next, we address HRQOL following early identification or predictive genetic testing in some neurodegenerative diseases: Huntington disease, Alzheimer's disease, Parkinson's disease, Dementia with Lewy bodies, frontotemporal dementia, amyotrophic lateral sclerosis, prion diseases, hereditary ataxias, Dentatorubral-pallidoluysian atrophy and Wilson's disease. After a brief report of available direct-to-consumer genetic tests, we address the juxtaposition of earlier disease identification with assumed reluctance towards predictive genetic testing. Forty-one studies examining health related outcomes following predictive genetic testing for neurodegenerative disease suggested that (a) extreme or catastrophic outcomes are rare; (b) consequences commonly include transiently increased anxiety and/or depression; (c) most participants report no regret; (d) many persons report extensive benefits to receiving genetic information; and (e) stigmatization and discrimination for genetic diseases are poorly understood and policy and laws are needed. Caution is appropriate for earlier identification of neurodegenerative diseases but findings suggest further progress is safe, feasible and likely to advance clinical care. PMID:24036231

  19. Floodplains within reservoirs promote earlier spawning of white crappies Pomoxis annularis

    USGS Publications Warehouse

    Miranda, Leandro E.; Dagel, Jonah D.; Kaczka, Levi J.; Mower, Ethan; Wigen, S. L.

    2015-01-01

    Reservoirs impounded over floodplain rivers are unique because they may include within their upper reaches extensive shallow water stored over preexistent floodplains. Because of their relatively flat topography and riverine origin, floodplains in the upper reaches of reservoirs provide broad expanses of vegetation within a narrow range of reservoir water levels. Elsewhere in the reservoir, topography creates a band of shallow water along the contour of the reservoir where vegetation often does not grow. Thus, as water levels rise, floodplains may be the first vegetated habitats inundated within the reservoir. We hypothesized that shallow water in reservoir floodplains would attract spawning white crappies Pomoxis annularis earlier than reservoir embayments. Crappie relative abundance over five years in floodplains and embayments of four reservoirs increased as spawning season approached, peaked, and decreased as fish exited shallow water. Relative abundance peaked earlier in floodplains than embayments, and the difference was magnified with higher water levels. Early access to suitable spawning habitat promotes earlier spawning and may increase population fitness. Recognition of the importance of reservoir floodplains, an understanding of how reservoir water levels can be managed to provide timely connectivity to floodplains, and conservation of reservoir floodplains may be focal points of environmental management in reservoirs.

  20. Earlier-Season Vegetation Has Greater Temperature Sensitivity of Spring Phenology in Northern Hemisphere

    PubMed Central

    Shen, Miaogen; Tang, Yanhong; Chen, Jin; Yang, Xi; Wang, Cong; Cui, Xiaoyong; Yang, Yongping; Han, Lijian; Li, Le; Du, Jianhui; Zhang, Gengxin; Cong, Nan

    2014-01-01

    In recent decades, satellite-derived start of vegetation growing season (SOS) has advanced in many northern temperate and boreal regions. Both the magnitude of temperature increase and the sensitivity of the greenness phenology to temperature–the phenological change per unit temperature–can contribute the advancement. To determine the temperature-sensitivity, we examined the satellite-derived SOS and the potentially effective pre-season temperature (Teff) from 1982 to 2008 for vegetated land between 30°N and 80°N. Earlier season vegetation types, i.e., the vegetation types with earlier SOSmean (mean SOS for 1982–2008), showed greater advancement of SOS during 1982–2008. The advancing rate of SOS against year was also greater in the vegetation with earlier SOSmean even the Teff increase was the same. These results suggest that the spring phenology of vegetation may have high temperature sensitivity in a warmer area. Therefore it is important to consider temperature-sensitivity in assessing broad-scale phenological responses to climatic warming. Further studies are needed to explore the mechanisms and ecological consequences of the temperature-sensitivity of start of growing season in a warming climate. PMID:24505418

  1. Optimal HIV testing and earlier care: the way forward in Europe.

    PubMed

    Coenen, T; Lundgren, J; Lazarus, J V; Matic, S

    2008-07-01

    The articles in this supplement were developed from a recent pan-European conference entitled 'HIV in Europe 2007: Working together for optimal testing and earlier care', which took place on 26-27 November in Brussels, Belgium. The conference, organized by a multidisciplinary group of experts representing advocacy, clinical and policy areas of the HIV field, was convened in an effort to gain a common understanding on the role of HIV testing and counselling in optimizing diagnosis and the need for earlier care. Key topics discussed at the conference and described in the following articles include: current barriers to HIV testing across Europe, trends in the epidemiology of HIV in the region, problems associated with undiagnosed infection and the psychosocial barriers impacting on testing. The supplement also provides a summary of the World Health Organization's recommendations for HIV testing in Europe and an outline of an indicator disease-guided approach to HIV testing proposed by a committee of experts from the European AIDS Clinical Society (EACS). We hope that consideration of the issues discussed in this supplement will help to shift the HIV field closer towards our ultimate goal: provision of optimal HIV testing and earlier care across the whole of the European region. PMID:18557862

  2. Bottom water variability in the subtropical northwestern Pacific from 26 kyr BP to present based on Mg / Ca and stable carbon and oxygen isotopes of benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Kubota, Y.; Kimoto, K.; Itaki, T.; Yokoyama, Y.; Miyairi, Y.; Matsuzaki, H.

    2015-06-01

    To understand bottom water variability in the subtropical northwestern Pacific, bottom water temperatures (BWTs), carbon isotopes (δ13C), and oxygen isotopes of seawater (δ18Ow) at a water depth of 1166 m were reconstructed from 26 kyr BP to present. A new regional Mg / Ca calibration for the benthic foraminifera Cibicidoides wuellerstorfi (type B) was established to convert the benthic Mg / Ca value to BWT, based on 26 surface sediment samples and two core-top samples retrieved around Okinawa Island. During the Last Glacial Maximum (LGM), the δ18Ow in the intermediate water in the northwestern South Pacific was ~0.4‰ lower than in the deep South Pacific, indicating a greater vertical salinity gradient than at present. This salinity (and probably density) structure would have led to stratification in the intermediate and deep Pacific, which would, in turn, have greatly influenced carbon storage during the glacial time. The benthic Mg / Ca and δ18Ow records suggest changes that seem to follow Heinrich event 1 (H1) and the Bølling-Alleød (B/A) and Younger Dryas (YD) intervals, with BWT higher during H1 (~17 kyr BP) and YD (~12 kyr BP) and lower during B/A (~14 kyr BP). The warming in the bottom water during H1 suggests increased contribution of North Pacific Intermediate Water (NPIW) to the subtropical northwestern Pacific and decreased upwelling of cooler waters from the abyssal North Pacific. During the interval from 17 to 14.5 kyr BP, the BWT tended to decrease successively in association with a decrease in δ13C values, presumably as a result of increased upwelling of the abyssal waters to the intermediate depths of the North Pacific caused by shoaling and enhancement of the southward return flow of Pacific Deep Water (PDW). During the Holocene, the millennial- to sub-millennial-scale variations in the BWT generally correlate with the sea surface temperatures in the Okhotsk Sea, the source region of the NPIW, suggesting that changes in the BWT are linked

  3. Precessional changes in the western equatorial Pacific Hydroclimate: A 240 kyr marine record from the Halmahera Sea, East Indonesia

    NASA Astrophysics Data System (ADS)

    Dang, Haowen; Jian, Zhimin; Kissel, Catherine; Bassinot, Franck

    2015-01-01

    the precession band, an interhemispheric antiphase pattern in the tropical hydroclimate is supported by many paleorecords, and optimally explained by the forcing of precessional insolation change. However, scenarios within the western equatorial Pacific (WEP), which plays the role of the ascending center of atmospheric convection, remain poorly determined. In this study, a marine sediment core from the Halmahera Sea, East Indonesia, was analyzed with high-resolution XRF scanning, quantitative discrete XRF, and ICP-AES/MS measurements. The terrigenous fractions in this core are constrained by their trace elemental characteristics to be locally sourced from Halmahera Island, and hence reflect variations in the local riverine runoff and precipitation. On this basis, a continuous record of precipitation changes of the western equatorial Pacific was reconstructed with multidecadal resolution over the last ˜240 ka, using an age model established by the correlation between an adjusted ice volume model and benthic δ18O constrained by 14C dating. The records of terrigenous input show a dominant ˜23 kyr periodicity with a 90°˜100° phase lag to the boreal summer (i.e., in-phase with the boreal autumn) insolation change. This pattern can be explained by the variability in the convective activity over the WEP, which might be primarily controlled by precessional changes in the El Niño and Southern Oscillation (ENSO) system. A dynamic linkage is implied between the precessional variations in the convective activity in the WEP and the East Asian and Australia-Indonesian summer monsoons (EASM and AISM), in the sense of their distinct stable phase relationship to precession.

  4. Links between carbonate productivity and ENSO variability in the southern California Current System for the past 2 Kyrs

    NASA Astrophysics Data System (ADS)

    Abella-Gutiérrez, J. L.; Herguera, J. C.

    2014-12-01

    San Lázaro Basin (SLB) is a suboxic basin characteristic for its very high sedimentation rates (1mm/yr) and is located in the dynamic southern boundary of the California Current System (CCS). This southern boundary of the CCS generally extends further south during spring into early summer and retracts towards the north during fall and winter, and this pattern is further amplified or reduced on different time scales, (e.i. interannual timescales by El Niño and La Niña events, or multidecadal ones by the Pacific Decadal Oscillation (PDO)). These oceanographic conditions are related with important differences in the base of the food chain; when the boundary migrates to northern latitudes, the presence of relatively warmer tropical and subtropical waters further stratify the water column, a period when coccolithophorids dominate the microplankton web structure. On the other side, diatoms flourish when the wind-driven circulation expand the subarctic water masses of the CCS to the south and upwelling cells are generated. We find in our cores XRF Ca counts (1 mm resolution) highly correlate with CaCO3 measurements (R=0.56), this last one showing a general decreasing trend over the past 2 Kyrs. The Ca spectrum analysis shows significant peaks for periods centered at 28, 40, 60, 120 yr. The centennial mode of variability of the Ca record shows correlations with Drought area Index from North America. When the variance of this mode is considered, similarities arises with intensity and number of ENSO events from Equatorial archives. Decadal variations of the record are highly correlated (R>0.8) with instrumental measurements of Kaplan sea surface temperature, and the PDO. We will discuss the implications of these periods in the carbonate record and the links between them and other paleoceanographic records in the Pacific.

  5. Heavy mineral variation in the deep sea sediment of southeastern Arabian Sea during the past 32 kyr

    NASA Astrophysics Data System (ADS)

    Akaram, Vaseem; Das, S. S.; Rai, A. K.; Mishra, Gaurav

    2015-03-01

    The present study is based on heavy mineral assemblages (HM) of top 104-cm thick section of gravity core SK 221 (Lat. 8∘7.12'N; Long. 73∘16.38'E and water depth - 2188 m) located near the Chagos-Laccadive Ridge in the southeastern Arabian Sea to evaluate the provenance and paleoenvironmental changes during the last 32 kyr. The biogenic carbonate, acid insoluble residue, magnetic susceptibility, total organic carbon (TOC) and clay based humidity index, i.e., kaolinite/illite ratio are also utilized to correlate with the above paleoenvironmental changes. Ilmenite, garnet, staurolite, pyroxenes, andalusite and zircon are the dominant HM with moderate to low ZTR (zircon-tourmaline-rutile) index indicating instability of the sediments and rapid erosion in the source region. The characteristic HM suggest their mixed sources from the basic igneous, gneisses/granites, high grade metamorphic rocks and sandstones occurring mainly in the western and southwestern India. The temporal variations of HM, AIR (acid insoluble residue), MS (magnetic susceptibility), biogenic carbonate and Corg (TOC) during preglacial and early Holocene suggest intensive weathering, erosion, and transportation of terrigenous detritus from continental region by fluvial processes and summer monsoon led high biogenic productivity, respectively. The convective mixing of waters due to intense winter monsoon resulted in very high biogenic carbonate content during the early stages of glacial period. The HM and associated proxies indicated that the winter monsoons of Heinrich (H3, H2, and H1) and Younger Dryas (YD) events and summer monsoons of Bølling/Allerød (BA) event were not strong enough to bring drastic changes in the above parameters.

  6. Hypoxia-driven variations in iron and manganese shuttling in the Baltic Sea over the past 8 kyr

    NASA Astrophysics Data System (ADS)

    Lenz, Conny; Jilbert, Tom; Conley, Daniel J.; Slomp, Caroline P.

    2015-10-01

    The Baltic Sea has experienced three major intervals of bottom water hypoxia following the intrusion of seawater circa 8 kyr ago. These intervals occurred during the Holocene Thermal Maximum (HTM), Medieval Climate Anomaly (MCA), and during recent decades. Here we show that sequestration of both Fe and Mn in Baltic Sea sediments generally increases with water depth, and we attribute this to shelf-to-basin transfer ("shuttling") of Fe and Mn. Burial of Mn in slope and basin sediments was enhanced following the lake-brackish/marine transition at the beginning of the hypoxic interval during the HTM. During hypoxic intervals, shelf-to-basin transfer of Fe was generally enhanced but that of Mn was reduced. However, intensification of hypoxia within hypoxic intervals led to decreased burial of both Mn and Fe in deep basin sediments. This implies a nonlinearity in shelf Fe release upon expanding hypoxia with initial enhanced Fe release relative to oxic conditions followed by increased retention in shelf sediments, likely in the form of iron sulfide minerals. For Mn, extended hypoxia leads to more limited sequestration as Mn carbonate in deep basin sediments, presumably because of more rapid reduction of Mn oxides formed after inflows and subsequent escape of dissolved Mn to the overlying water. Our Fe records suggest that modern Baltic Sea hypoxia is more widespread than in the past. Furthermore, hypoxia-driven variations in shelf-to-basin transfer of Fe may have impacted the dynamics of P and sulfide in the Baltic Sea thus providing potential feedbacks on the further development of hypoxia.

  7. Mindanao Dome variability over the last 160 kyr: Episodic glacial cooling of the West Pacific Warm Pool

    NASA Astrophysics Data System (ADS)

    Bolliet, Timothé; Holbourn, Ann; Kuhnt, Wolfgang; Laj, Carlo; Kissel, Catherine; Beaufort, Luc; Kienast, Markus; Andersen, Nils; Garbe-Schönberg, Dieter

    2011-02-01

    We present sea surface, upper thermocline, and benthic δ18O data, as well as temperature and paleoproductivity proxy data, from the International Marine Global Change Study Program (IMAGES) Core MD06-3067 (6°31‧N, 126°30‧E, 1575 m water depth), located in the western equatorial Pacific Ocean within the flow path of the Mindanao Current. Our records reveal considerable glacial-interglacial and suborbital variability in the Mindanao Dome upwelling over the last 160 kyr. Dome activity generally intensified during glacial intervals resulting in cooler thermocline waters, whereas it substantially declined during interglacials, in particular in the early Holocene and early marine oxygen isotope stage (MIS) 5e, when upwelling waters did not reach the thermocline. During MIS 3 and MIS 2, enhanced surface productivity together with remarkably low SST and low upper ocean thermal contrast provide evidence for episodic glacial upwelling to the surface, whereas transient surface warming marks periodic collapses of the Mindanao Dome upwelling during Heinrich events. We attribute the high variability during MIS 3 and MIS 2 to changes in the El Niño Southern Oscillation state that affected boreal winter monsoonal winds and upper ocean circulation. Glacial upwelling intensified when a strong cyclonic gyre became established, whereas El Niño-like conditions during Heinrich events tended to suppress the cyclonic circulation, reducing Ekman transport. Thus, our findings demonstrate that variations in the Mindanao Dome upwelling are closely linked to the position and intensity of the tropical convection and also reflect far-field influences from the high latitudes.

  8. Temperature variations in Greenland from 10 to 110 kyr b2k derived from the NGRIP ice core

    NASA Astrophysics Data System (ADS)

    Kindler, Philippe; Leuenberger, Markus; Landais, Amaelle; Guillevic, Myriam

    2013-04-01

    During the last ice age dramatic temperature variations of up to 16 °C took place in Greenland which are now known as Dansgaard-Oeschger-events (DO-events). They most probably originate from the North Atlantic oceanic and atmospheric circulation system and are characterised by an abrupt warming within decades followed by a gradual cooling over hundreds to thousands of years. We have determined local temperature variations for DO-event 1 to 25 in Greenland based on δ15N measurements from the NorthGRIP ice core, corresponding to the period from 10 to 110 kyr b2k. The record is a composite of measurements from two laboratories, Laboratoire des Sciences du Climat et de l'Environnement, Paris (DO 18 to 25) and the Climate and Environmental Physics Division of the Physics Institute of the University of Bern (DO 1 to 17) with new measurements from the beginning of the Holocene to DO 8. Temperature variations were reconstructed by reproducing the measured 15N/14N ratio of air enclosed in ice bubbles by the firn densification and heat diffusion model from Schwander. The reconstruction show temperature amplitudes for the DO-events ranging from 5 to 16 °C, thereby the corresponding rates of change can exceed 0.5 °C/decade. In order get an agreement between measured δ15N, Δdepth and Δage values with their modelled analogues, a lower accumulation rate than the one associated with the used ss09sea06bm1 time scale had to be assumed. We had to reduce the accumulation rate time dependently by 0 to nearly 40% with a mean reduction over the whole time period of 16%. With these adjustments both the Δdepth and the Δage values agree between model and measurements.

  9. Factors associated with late diagnosis of HIV infection and missed opportunities for earlier testing.

    PubMed

    Gullón, Alejandra; Verdejo, José; de Miguel, Rosa; Gómez, Ana; Sanz, Jesús

    2016-10-01

    Late diagnosis (LD) of human immunodeficiency virus (HIV) infection continues to be a significant problem that increases disease burden both for patients and for the public health system. Guidelines have been updated in order to facilitate earlier HIV diagnosis, introducing "indicator condition-guided HIV testing". In this study, we analysed the frequency of LD and associated risk factors. We retrospectively identified those cases that could be considered missed opportunities for an earlier diagnosis. All patients newly diagnosed with HIV infection who attended Hospital La Princesa, Madrid (Spain) between 2007 and 2014 were analysed. We collected epidemiological, clinical and immunological data. We also reviewed electronic medical records from the year before the HIV diagnosis to search for medical consultations due to clinical indicators. HIV infection was diagnosed in 354 patients. The median CD4 count at presentation was 352 cells/mm(3). Overall, 158 patients (50%) met the definition of LD, and 97 (30.7%) the diagnosis of advanced disease. LD was associated with older age and was more frequent amongst immigrants. Heterosexual relations and injection drug use were more likely to be the reasons for LD than relations between men who have sex with men. During the year preceding the diagnosis, 46.6% of the patients had sought medical advice owing to the presence of clinical indicators that should have led to HIV testing. Of those, 24 cases (14.5%) were classified as missed opportunities for earlier HIV diagnosis because testing was not performed. According to these results, all health workers should pursue early HIV diagnosis through the proper implementation of HIV testing guidelines. Such an approach would prove directly beneficial to the patient and indirectly beneficial to the general population through the reduction in the risk of transmission. PMID:27144427

  10. Changing the seasonality of an Arctic tundra ecosystem: earlier snowmelt and warmer temperatures

    NASA Astrophysics Data System (ADS)

    Steltzer, H.; Weintraub, M. N.; Darrouzet-Nardi, A.; Melle, C.; Segal, A.; Sullivan, P.; Landry, C.; Wallenstein, M. D.

    2010-12-01

    In the Arctic and around the world, earlier plant growth is an indication that warmer temperatures or other global changes are changing the seasonality of the Earth’s ecosystems. To determine how changes in seasonality affect plant life histories and biogeochemical cycles in tussock tundra, we established a factorial experiment that includes two approaches to changing the seasonality of this ecosystem. In early May, we placed radiation absorbing fabric on the snow surface to accelerate the timing of snowmelt. We monitored the rate of snowmelt over a 10 day period and removed the fabric on the 10th day when the accelerated plots were 80% snowfree. Instrument arrays placed in the plots collected daily data that characterize an increase in energy absorption in these snowfree areas over the 4 day period prior to when control areas were snowfree. In addition, when the plots became snowfree we placed open-top-chambers in areas with and without accelerated snowmelt. The chambers increased air temperatures especially during mid-day early in the growing season. The instrument arrays included light sensors to monitor the plant community life history by observing surface greenness. Our results suggest that the plant community initiated growth earlier when snowmelt occurred earlier and that warming speeded the development of the plant canopy. However, plant species’ life history responses to these changes in seasonality were variable. Experimental alteration of the timing of plant life history events will provide a useful tool to examine controls on the seasonality of biogeochemical processes, such as nutrient availability to plants and nutrient limitation of decomposition. Accelerated snowmelt and warmer temperatures in tussock tundra, AK.

  11. Economic Costs Avoided by Diagnosing Melanoma Six Months Earlier Justify >100 Benign Biopsies.

    PubMed

    Aires, Daniel J; Wick, Jo; Shaath, Tarek S; Rajpara, Anand N; Patel, Vikas; Badawi, Ahmed H; Li, Cicy; Fraga, Garth R; Doolittle, Gary; Liu, Deede Y

    2016-05-01

    New melanoma drugs bring enormous benefits but do so at significant costs. Because melanoma grows deeper and deadlier over time, deeper lesions are costlier due to increased sentinel lymph node biopsy, chemotherapy, and disease-associated income loss. Prior studies have justified pigmented lesion biopsies on a "value per life" basis; by contrast we sought to assess how many biopsies are justified per melanoma found on a purely economic basis. We modeled how melanomas in the United States would behave if diagnosis were delayed by 6 months, eg, not biopsied, only observed until the next surveillance visit. Economic loss from delayed biopsy is the obverse of economic benefit of performing biopsy earlier. Growth rates were based on Liu et al. The results of this study can be applied to all patients presenting to dermatologists with pigmented skin lesions suspicious for melanoma. In-situ melanomas were excluded because no studies to date have modeled growth rates analogous to those for invasive melanoma. We assume conservatively that all melanomas not biopsied initially will be biopsied and treated 6 months later. Major modeled costs are (1) increased sentinel lymph node biopsy, (2) increased chemotherapy for metastatic lesions using increased 5-yr death as metastasis marker, and (3) income loss per melanoma death at $413,370 as previously published. Costs avoided by diagnosing melanoma earlier justify 170 biopsies per melanoma found. Efforts to penalize "unnecessary" biopsies may be economically counterproductive.

    J Drugs Dermatol. 2016;15(5):527-532. PMID:27168261

  12. Empirical corroboration of an earlier theoretical resolution to the UV paradox of insect polarized skylight orientation.

    PubMed

    Wang, Xin; Gao, Jun; Fan, Zhiguo

    2014-02-01

    It is surprising that many insect species use only the ultraviolet (UV) component of the polarized skylight for orientation and navigation purposes, while both the intensity and the degree of polarization of light from the clear sky are lower in the UV than at longer (blue, green, red) wavelengths. Why have these insects chosen the UV part of the polarized skylight? This strange phenomenon is called the "UV-sky-pol paradox". Although earlier several speculations tried to resolve this paradox, they did this without any quantitative data. A theoretical and computational model has convincingly explained why it is advantageous for certain animals to detect celestial polarization in the UV. We performed a sky-polarimetric approach and built a polarized skylight sensor that models the processing of polarization signals by insect photoreceptors. Using this model sensor, we carried out measurements under clear and cloudy sky conditions. Our results showed that light from the cloudy sky has maximal degree of polarization in the UV. Furthermore, under both clear and cloudy skies the angle of polarization of skylight can be detected with a higher accuracy. By this, we corroborated empirically the soundness of the earlier computational resolution of the UV-sky-pol paradox. PMID:24402685

  13. Empirical corroboration of an earlier theoretical resolution to the UV paradox of insect polarized skylight orientation

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Gao, Jun; Fan, Zhiguo

    2014-02-01

    It is surprising that many insect species use only the ultraviolet (UV) component of the polarized skylight for orientation and navigation purposes, while both the intensity and the degree of polarization of light from the clear sky are lower in the UV than at longer (blue, green, red) wavelengths. Why have these insects chosen the UV part of the polarized skylight? This strange phenomenon is called the "UV-sky-pol paradox". Although earlier several speculations tried to resolve this paradox, they did this without any quantitative data. A theoretical and computational model has convincingly explained why it is advantageous for certain animals to detect celestial polarization in the UV. We performed a sky-polarimetric approach and built a polarized skylight sensor that models the processing of polarization signals by insect photoreceptors. Using this model sensor, we carried out measurements under clear and cloudy sky conditions. Our results showed that light from the cloudy sky has maximal degree of polarization in the UV. Furthermore, under both clear and cloudy skies the angle of polarization of skylight can be detected with a higher accuracy. By this, we corroborated empirically the soundness of the earlier computational resolution of the UV-sky-pol paradox.

  14. Association of Family History of Epilepsy with Earlier Age Onset of Juvenile Myoclonic Epilepsy

    PubMed Central

    2016-01-01

    Objective Juvenile myoclonic epilepsy (JME) is supposedly the most frequent subtype of idiopathic generalized epilepsies (IGE). The aim of this study was to determine the prevalence of JME and comparison of patients’ demographics as well as timeline of the disease between positive family history epileptic patients (PFHE) and negative family history epileptic patients (NFHE) among sample of Iranian epileptic patients. Materials & Methods From Feb. 2006 to Oct. 2009, 1915 definite epileptic patients (873 females) referred to epilepsy clinics in Isfahan, central Iran, were surveyed and among them, 194 JME patients were diagnosed. JME was diagnosed by its specific clinical and EEG criteria. Patients were divided into two groups as PFHE and NFHE and data were compared between them. Results JME was responsible for 10% (194 patients) of all types of epilepsies. Of JME patients, 53% were female. In terms of family history of epilepsy, 40% were positive. No significant differences was found between PFHE and NFHE groups as for gender (P>0.05). Age of epilepsy onset was significantly earlier in PFHE patients (15 vs. 22 yr, P<0.001). Occurrence of JME before 18 yr old among PFHE patients was significantly higher (OR=2.356, P=0.007). Conclusion A family history of epilepsy might be associated with an earlier age of onset in patients with JME. PMID:27247579

  15. Light pollution is associated with earlier tree budburst across the United Kingdom.

    PubMed

    Ffrench-Constant, Richard H; Somers-Yeates, Robin; Bennie, Jonathan; Economou, Theodoros; Hodgson, David; Spalding, Adrian; McGregor, Peter K

    2016-06-29

    The ecological impact of night-time lighting is of concern because of its well-demonstrated effects on animal behaviour. However, the potential of light pollution to change plant phenology and its corresponding knock-on effects on associated herbivores are less clear. Here, we test if artificial lighting can advance the timing of budburst in trees. We took a UK-wide 13 year dataset of spatially referenced budburst data from four deciduous tree species and matched it with both satellite imagery of night-time lighting and average spring temperature. We find that budburst occurs up to 7.5 days earlier in brighter areas, with the relationship being more pronounced for later-budding species. Excluding large urban areas from the analysis showed an even more pronounced advance of budburst, confirming that the urban 'heat-island' effect is not the sole cause of earlier urban budburst. Similarly, the advance in budburst across all sites is too large to be explained by increases in temperature alone. This dramatic advance of budburst illustrates the need for further experimental investigation into the impact of artificial night-time lighting on plant phenology and subsequent species interactions. As light pollution is a growing global phenomenon, the findings of this study are likely to be applicable to a wide range of species interactions across the world. PMID:27358370

  16. Light pollution is associated with earlier tree budburst across the United Kingdom

    PubMed Central

    Somers-Yeates, Robin; Bennie, Jonathan; Hodgson, David; Spalding, Adrian

    2016-01-01

    The ecological impact of night-time lighting is of concern because of its well-demonstrated effects on animal behaviour. However, the potential of light pollution to change plant phenology and its corresponding knock-on effects on associated herbivores are less clear. Here, we test if artificial lighting can advance the timing of budburst in trees. We took a UK-wide 13 year dataset of spatially referenced budburst data from four deciduous tree species and matched it with both satellite imagery of night-time lighting and average spring temperature. We find that budburst occurs up to 7.5 days earlier in brighter areas, with the relationship being more pronounced for later-budding species. Excluding large urban areas from the analysis showed an even more pronounced advance of budburst, confirming that the urban ‘heat-island’ effect is not the sole cause of earlier urban budburst. Similarly, the advance in budburst across all sites is too large to be explained by increases in temperature alone. This dramatic advance of budburst illustrates the need for further experimental investigation into the impact of artificial night-time lighting on plant phenology and subsequent species interactions. As light pollution is a growing global phenomenon, the findings of this study are likely to be applicable to a wide range of species interactions across the world. PMID:27358370

  17. Treatment as prevention: are Argentinean HIV care providers willing to adopt earlier antiretroviral therapy?

    PubMed

    Socías, María Eugenia; Sued, Omar; Pryluka, Daniel; Patterson, Patricia; Fink, Valeria; Cesar, Carina; Cahn, Pedro

    2014-01-01

    HIV guidelines increasingly recommend antiretroviral therapy (ART) initiation at a higher CD4 levels. The extent to which these evolving standards are translated into routine clinical care has not been evaluated in Argentina. During October 2012, we conducted an online survey among Argentinean HIV clinicians to assess their attitudes and practices toward ART initiation and its potential use for HIV prevention. Of the 280 physicians included, 61% would prescribe ART at CD4 ≤ 500 cells/µL for asymptomatic patients. Although, only 11% would recommend ART irrespective of CD4 cell count, 72% would do it for serodiscordant couples, and 75% for sex workers. Most participants agreed that they would consider earlier initiation of ART if transmission risk exists, and that expansion of ART could help decrease HIV incidence. These results suggest that a large proportion of Argentinean HIV care providers are willing to adopt the recently updated Argentinean guidelines recommending earlier ART, especially when high HIV transmission risk exists. PMID:24773142

  18. Grounded spatial belief revision.

    PubMed

    Nejasmic, Jelica; Bucher, Leandra; Knauff, Markus

    2015-05-01

    Beliefs frequently undergo revisions, especially when new pieces of information are true but inconsistent with current beliefs. In previous studies, we showed that linguistic asymmetries provided by relational statements, play a crucial role in spatial belief revision. Located objects (LO) are preferably revised compared to reference objects (RO), known as the LO-principle. Here we establish a connection between spatial belief revision and grounded cognition. In three experiments, we explored whether imagined physical object properties influence which object is relocated and which remains at its initial position. Participants mentally revised beliefs about the arrangements of objects which could be envisaged as light and heavy (Experiment 1), small and large (Experiment 2), or movable and immovable (Experiment 3). The results show that intrinsic object properties are differently taken into account during spatial belief revision. Object weight did not alter the LO-principle (Experiment 1), whereas object size was found to influence which object was preferably relocated (Experiment 2). Object movability did not affect relocation preferences but had an effect on relocation durations (Experiment 3). The findings support the simulation hypothesis within the grounded cognition approach and create new connections between the spatial mental model theory of reasoning and the idea of grounded cognition. PMID:25796056

  19. The Fischa-Dagnitz spring, Southern Vienna Basin: a multi tracer time series study re-assessing earlier conceptual assumptions.

    NASA Astrophysics Data System (ADS)

    Suckow, Axel; Gerber, Christoph; Kralik, Martin; Sültenfuss, Jürgen; Purtschert, Roland

    2013-04-01

    The gravel aquifer of the Southern Vienna Basin is a very important backup drinking water resource for the city of Vienna. A discharge location, the Fischa-Dagnitz spring in the Southern Vienna Basin, Austria, was re-investigated in 2011, five years after the gas exchange tracer test published in (Stolp et al., 2010), and sampled for stable isotopes 18O/2H, tritium, 3He, SF6 and 85Kr (Gerber et al., 2012). Additionally, new tritium time series data (Davis et al., 1967), previously not considered in Stolp et al. (2010), were included. These show a higher and earlier tritium peak of >300 TU in 1965 in the discharge of the Fischa-Dagnitz spring as compared to 221 TU in 1972 considered in Stolp et al. (2010). The new 3He, SF6 and 85Kr gas tracer data from 2011 confirm the earlier finding for 3He of Stolp et al. (2010) and indicate a more recent equilibration with the atmosphere than the water bound tracers 18O, 2H and tritium. A new modelling attempt using the Lumpy code (Suckow, 2012) confirmed the discrepancy between the tritium data and the gaseous tracers 3He, SF6 and 85Kr. No steady-state combination of local recharge (represented by an exponential model) and Schwarza river infiltration flowing through the gravel aquifer (represented by a parallel dispersion model) can equally well explain both the tritium time series and the gas tracer results. A revised conceptual model proposes that a pinching of the aquifer at unconformities in the gravel body or a fault zone known in the gravel body forces groundwater along the flow path closer to the surface and exposes it to the atmosphere. This would tend to reset the "dating" clock for the gaseous tracers 3He, SF6 and 85Kr, which can equilibrate quickly with the atmosphere, but not for tritium, which marks the transport behaviour of the water itself. These findings are of importance also for other multi-tracer assessments of groundwater movement in phreatic aquifer systems. References: Davis, G.H., Payne, B.R., Dincer, T

  20. Northern Component Water Variability Over the Past 21 kyr: High-resolution Records From Eirik and Gardar Drifts

    NASA Astrophysics Data System (ADS)

    Elmore, A. C.; Wright, J. D.; Neitzke, L. C.; Henderson, S.

    2007-12-01

    Northern Component Water (NCW; analogous to modern NADW) circulation has been described as bi-modal with shallow flow associated with the last glacial maximum (LGM) and a deeper current associated with the Holocene. We have generated foraminiferal stable isotope records as well as grain size records from cores collected on the Eirik and southern Gardar Drifts. Our records show that the shallow mode of NCW circulation persisted through the deglacial and into the early Holocene. Beginning around 9 ka (calendar age), the core of NCW began to descend, reaching its present position by 8 ka. This is consistent with Fagel et al. (2002) who argued that Denmark Strait overflow, which is the densest contributor to NCW, began around 8.5 ka. We note also that benthic foraminiferal oxygen isotope data from Gardar diverged from the Eirik data during the late deglacial and early Holocene, and may indicate the resumption of flow over the Iceland-Faroe Ridge and/or through the Faroe Bank Channel. Higher frequency changes in the benthic foraminiferal carbon isotopes during the late glacial through deglacial record interruptions in NCW flow. A 1 per mil decrease occurred from 18 to 16 ka. This decrease was associated with a 4-fold decrease in sedimentation rates and is interpreted as a further shoaling of NCW and influx of AABW. The start of this decrease predates the H1 event but the carbon isotope decrease continued through the H1 event, reaching minimum values at 16.3 ka. Between 16.3 and 14.0 ka, carbon isotope values fluctuated between 0 and 0.75 per mil. Sedimentation rates increased sharply to rates >25 cm/kyr, indicating that the current was actively supplying sediments with minimal winnowing. At 14 ka, carbon isotope values increased to ~1 per mil, associated with the Bolling-Allerod warming, and fluctuated about a mean of 1 per mil until the beginning of the Younger Dryas at 12.5ka. During the Younger Dryas, benthic carbon isotope values decreased by 0.5 per mil, signaling

  1. South Asian summer monsoon variability during the last ˜54 kyrs inferred from surface water salinity and river runoff proxies

    NASA Astrophysics Data System (ADS)

    Gebregiorgis, D.; Hathorne, E. C.; Sijinkumar, A. V.; Nath, B. Nagender; Nürnberg, D.; Frank, M.

    2016-04-01

    The past variability of the South Asian Monsoon is mostly known from records of wind strength over the Arabian Sea while high-resolution paleorecords from regions of strong monsoon precipitation are still lacking. Here, we present records of past monsoon variability obtained from sediment core SK 168/GC-1, which was collected at the Alcock Seamount complex in the Andaman Sea. We utilize the ecological habitats of different planktic foraminiferal species to reconstruct freshwater-induced stratification based on paired Mg/Ca and δ18O analyses and to estimate seawater δ18O (δ18Osw). The difference between surface and thermocline temperatures (ΔT) and δ18Osw (Δδ18Osw) is used to investigate changes in upper ocean stratification. Additionally, Ba/Ca in G. sacculifer tests is used as a direct proxy for riverine runoff and sea surface salinity (SSS) changes related to monsoon precipitation on land. Our Δδ18Osw time series reveals that upper ocean salinity stratification did not change significantly throughout the last glacial suggesting little influence of NH insolation changes. The strongest increase in temperature gradients between the mixed layer and the thermocline is recorded for the mid-Holocene and indicate the presence of a significantly shallower thermocline. In line with previous work, the δ18Osw and Ba/Ca records demonstrate that monsoon climate during the LGM was characterized by a significantly weaker southwest monsoon circulation and strongly reduced runoff. Based on our data the South Asian Summer Monsoon (SAM) over the Irrawaddyy strengthened gradually after the LGM beginning at ˜18 ka. This is some 3 kyrs before an increase of the Ba/Ca record from the Arabian Sea and indicates that South Asian Monsoon climate dynamics are more complex than the simple N-S displacement of the ITCZ as generally described for other regions. Minimum δ18Osw values recorded during the mid-Holocene are in phase with Ba/Ca marking a stronger monsoon precipitation

  2. South Asian summer monsoon variability during the last ˜54 kyrs inferred from surface water salinity and river runoff proxies

    NASA Astrophysics Data System (ADS)

    Gebregiorgis, D.; Hathorne, E. C.; Sijinkumar, A. V.; Nath, B. Nagender; Nürnberg, D.; Frank, M.

    2016-04-01

    The past variability of the South Asian Monsoon is mostly known from records of wind strength over the Arabian Sea while high-resolution paleorecords from regions of strong monsoon precipitation are still lacking. Here, we present records of past monsoon variability obtained from sediment core SK 168/GC-1, which was collected at the Alcock Seamount complex in the Andaman Sea. We utilize the ecological habitats of different planktic foraminiferal species to reconstruct freshwater-induced stratification based on paired Mg/Ca and δ18O analyses and to estimate seawater δ18O (δ18Osw). The difference between surface and thermocline temperatures (ΔT) and δ18Osw (Δδ18Osw) is used to investigate changes in upper ocean stratification. Additionally, Ba/Ca in G. sacculifer tests is used as a direct proxy for riverine runoff and sea surface salinity (SSS) changes related to monsoon precipitation on land. Our Δδ18Osw time series reveals that upper ocean salinity stratification did not change significantly throughout the last glacial suggesting little influence of NH insolation changes. The strongest increase in temperature gradients between the mixed layer and the thermocline is recorded for the mid-Holocene and indicate the presence of a significantly shallower thermocline. In line with previous work, the δ18Osw and Ba/Ca records demonstrate that monsoon climate during the LGM was characterized by a significantly weaker southwest monsoon circulation and strongly reduced runoff. Based on our data the South Asian Summer Monsoon (SAM) over the Irrawaddyy strengthened gradually after the LGM beginning at ∼18 ka. This is some 3 kyrs before an increase of the Ba/Ca record from the Arabian Sea and indicates that South Asian Monsoon climate dynamics are more complex than the simple N-S displacement of the ITCZ as generally described for other regions. Minimum δ18Osw values recorded during the mid-Holocene are in phase with Ba/Ca marking a stronger monsoon precipitation

  3. Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos

    NASA Astrophysics Data System (ADS)

    Yang, Hongying

    I present a high- resolution record of Southeast Asian Monsoon (SEAM) evolution compiled from delta18O measurements conducted on five U-Th dated speleothems from Tham Mai Cave in northern Laos (20.75N, 102.65E), a key site at the interface between the Indian and East Asian monsoon systems. The speleothem oxygen isotope records are tied to robust uranium-series dates and indicate the records span from 0.79 to 13 kyr BP with sub-decadal resolution. During the Holocene, the Tham Mai speleothem delta18O records are characterized by lower values during the early to mid-Holocene with increasing values towards the late Holocene. This is similar to trends seen throughout the Asian monsoon region, reflecting the strong insolation control on monsoon strength and ITCZ position. The Younger Dryas is characterized by an abrupt delta 18O increase and is synchronous with the even observed in Chinese speleothem records and Greenland ice cores within age uncertainties. This suggests that the SEAM weakened in sync with high-latitude abrupt cooling events. Four speleothems from Tham Mai cave grew contemporaneously from 4,300 years BP to 9,000 years BP. These four samples show a similar delta 18O pattern, despite a 1.2‰ between sample delta18 O variability is observed. A lumped parameter forward model method (KarstFor model) is used to assess to which extent this 1.2‰ discrepancy can be attributed to hydrological variability. Results suggested that this 1.2‰ discrepancy can be generated due to hydrological variability within one cave. To better interpret interannual delta18O variability in high-resolution oxygen isotope records in the Asian Monsoon region, I utilize existing simulations from a spectrally nudged isotope-enabled general circulation model (IsoGSM) to investigate the climatic controls on delta18 Op at four cave locations along the Asian monsoon region. Results show that delta18Op at the four cave sites reflects large-scale ocean-atmosphere processes, instead of

  4. Distal deltaic deposits document hydrological variability during the past 30 kyrBP in Lake Towuti, Indonesia

    NASA Astrophysics Data System (ADS)

    Vogel, Hendrik; Russell, James M.; Yudawati Cahyarini, Sri; Bijaksana, Satria; Wattrus, Nigel; Rethemeyer, Janet; Melles, Martin

    2014-05-01

    Lake Towuti (2.75°S, 121.5°E; 318 m a.s.l.) is a, 560 km2, 200-m deep tectonic lake at the downstream end of the Malili lake system, a set of five, ancient (1-2 MYr) tectonic lakes in central Sulawesi, Indonesia. The Mahalona River constitutes the largest tributary and connects Lake Towuti with the two upstream lakes Matano and Mahalona. The Mahalona River Delta is prograding into the >200m deep northern basin of Lake Towuti. Tracing past variability of Mahalona River discharge is therefore an important puzzle piece for the understanding of depositional dynamics in Lake Towuti as well as catchment hydrology and hydrological connectivity between the Malili Lakes. Distal deltaic deposits can help identifying past variability in river discharge and delta dynamics. Using highly resolved seismic reflection data collected between 2007-2013 we identified a stack of acoustically laminated reflections in Towuti's extensive and morphologically flat deep northern basin. For detailed characterization of these acoustic features we collected a c. 20m long piston core from the basin centre at 200 m water depth reaching back to c. 30 kyrBP. Sediments in this piston core consist to 75% of mass wasting deposits (MWD) of variable thickness that are intercalated with pelagic muds (25%). MWD appear mostly homogenous (silt- to finesand-sized siliciclastics with high amounts of terrestrial plant macrofossils) with only thin (1-3 cm) basal sand layers and clay caps (<1 cm). Pelagic muds appear as thin to medium bedded slightly silty clays that are clearly distinguishable from MWD. The position of MWD identified in our piston core nicely correlates with acoustically laminated reflections identified in seismic profiles crossing the coring site. Based on these combined sedimentological and acoustic datasets we interpret MWD in Towuti's northern basin as distal deltaic deposits originating from the Mahalona River Delta. Frequencies and percentages (in terms of lithofacies contribution) of

  5. Multi-proxy sedimentary record from Lake Ghirla (N-Italy) reveals hydro-climatic variations and periods of anthropogenic activities during the past 13 kyrs

    NASA Astrophysics Data System (ADS)

    Wirth, Stefanie B.; Gilli, Adrian; Sessions, Alex L.

    2016-04-01

    Lake Ghirla is a small lake that lies in the southern foothills of the Central Alps near the Swiss-Italian border. Climatically, the region is influenced by North Atlantic and Mediterranean weather systems and is frequently affected by severe storm tracks causing heavy precipitation. The catchment with Permian granites and gneisses contains Pb in amounts significant for mining as well as less important concentrations of Cu, As and U. This sensitive setting makes Lake Ghirla a promising site to reconstruct hydro-climatic variations and to track human activity by means of elevated heavy metal concentrations in the lake sediments. The recovered sediment core comprises the entire Younger Dryas-Holocene time period and was analyzed for (i) sedimentological changes to identify flood deposits, for (ii) the hydrogen isotopic composition of terrestrial plant waxes (plant-wax D/H) to constrain hydro-climatic changes, and for (iii) variations of the elemental composition (XRF core scanning, ICP-MS) to understand anthropogenic impacts. During the past 13 kyrs, we observe a high variability of floods with peak periods appearing at ~11, 10.6-8.2, 6-4.9, 2.8-2.7, 2.6-2.4, 1.2-1 and 0.4-0.1 (LIA) cal kyr BP. From a hydro-climatic perspective, the most remarkable result from the plant-wax D/H data is that the Younger Dryas is characterized by no significant change and that the 2.8-2.7 kyr BP and LIA intervals show an increase of plant-wax D/H values. Hence, during these three cool climatic periods temperature effects cannot be solely responsible for plant-wax D/H variation. The southward migration of the westerly storm tracks above the North Atlantic due to climate cooling must have led to a more southern and thus isotopically enriched moisture source for the southern Alps. This moisture-source change likely counter-balanced or even over-rode the temperature-driven isotope effect. Increased sedimentary Cu concentrations at 3.8-3.3 kyr BP are the first evidence for the presence of

  6. Orbital-scale stratigraphy and paleoenvironmental changes in the Japan Sea during the last 230 kyr based on oxygen and carbon isotopes of benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Nakahashi, K.; Kimoto, K.; Tada, R.; Tamaki, K.

    2009-12-01

    Paleoceanographic conditions in the Japan Sea changed drastically during the late Quaternary in association with orbital and suborbital cycles and glacio-eustatic sea level changes. However, few studies had been examined long-term sediment records older than last intergracial period because of the lack of long cores which contains continuous paleoclimatic records and difficulties reconstructing high-resolution age models. Especially disappearance of benthic foraminifers by euxinic bottom water conditions during glacial maxima makes it difficult to understand specific bottom water environments. In this study, we reconstructed benthic foraminiferal stable isotopic stratigraphy of the Japan Sea core with the resolution in 2 kyr. and compared the global stack of benthic foraminfieral δ18O curve (LR04, Lisiecki & Raymo, 2005). The investigated core MD01-2408, was recovered from 806 m water depth, off Akita Prefecture during IMAGES VII cruise. It had recorded continuous paleoenvironmental histories during the last 230 kyr through the core. This core was mainly consisted of alternating layers of homogeneous light colored silty clay and laminated or bioturbated dark colored silty clay, occasionally intercalating volcanic ash layers. The most abundant benthic foraminiferal species are Uvigerina akitaensis, Angulogerina kokozuraensis and Islandiella norcrossi. Abundance of these species fluctuated drastically through the core. No benthic foraminifera is found in two dark layer intervals 4 ~ 5 mbsf and 25 ~ 25.5 mbsf, corresponding 15 ~ 25 kyr and 149 ~ 152 kyr, respectively, probably representing super anoxic bottom water conditions(Oba et al 1984 1991;Tada et al., 1999). δ18O of U. akitaensis and A. kokozuraensis showed a similar values with a precision of ± 0.27‰ and it was inferred that both species had similar habitat. δ18O of both species in core MD01-2408 fluctuated with the range of 2‰ over 230 kyr. Although benthic δ18O stack of LR04 reached to 5 ‰ during

  7. Earlier versus Later Start of Antiretroviral Therapy in HIV-Infected Adults with Tuberculosis

    PubMed Central

    Blanc, François-Xavier; Sok, Thim; Laureillard, Didier; Borand, Laurence; Rekacewicz, Claire; Nerrienet, Eric; Madec, Yoann; Marcy, Olivier; Chan, Sarin; Prak, Narom; Kim, Chindamony; Lak, Khemarin Kim; Hak, Chanroeurn; Dim, Bunnet; Sin, Chhun Im; Sun, Sath; Guillard, Bertrand; Sar, Borann; Vong, Sirenda; Fernandez, Marcelo; Fox, Lawrence; Delfraissy, Jean-François; Goldfeld, Anne E.

    2016-01-01

    Background Tuberculosis remains an important cause of death among patients infected with the human immunodeficiency virus (HIV). Robust data are lacking with regard to the timing for the initiation of antiretroviral therapy (ART) in relation to the start of antituberculosis therapy. Methods We tested the hypothesis that the timing of ART initiation would significantly affect mortality among adults not previously exposed to antiretroviral drugs who had newly diagnosed tuberculosis and CD4+ T-cell counts of 200 per cubic millimeter or lower. After beginning the standard, 6-month treatment for tuberculosis, patients were randomly assigned to either earlier treatment (2 weeks after beginning tuberculosis treatment) or later treatment (8 weeks after) with stavudine, lamivudine, and efavirenz. The primary end point was survival. Results A total of 661 patients were enrolled and were followed for a median of 25 months. The median CD4+ T-cell count was 25 per cubic millimeter, and the median viral load was 5.64 log10 copies per milliliter. The risk of death was significantly reduced in the group that received ART earlier, with 59 deaths among 332 patients (18%), as compared with 90 deaths among 329 patients (27%) in the later-ART group (hazard ratio, 0.62; 95% confidence interval [CI]; 0.44 to 0.86; P = 0.006). The risk of tuberculosis-associated immune reconstitution inflammatory syndrome was significantly increased in the earlier-ART group (hazard ratio, 2.51; 95% CI, 1.78 to 3.59; P<0.001). Irrespective of the study group, the median gain in the CD4+ T-cell count was 114 per cubic millimeter, and the viral load was undetectable at week 50 in 96.5% of the patients. Conclusions Initiating ART 2 weeks after the start of tuberculosis treatment significantly improved survival among HIV-infected adults with CD4+ T-cell counts of 200 per cubic millimeter or lower. (Funded by the French National Agency for Research on AIDS and Viral Hepatitis and the National Institutes of

  8. Kathu Townlands: A High Density Earlier Stone Age Locality in the Interior of South Africa

    PubMed Central

    Walker, Steven J. H.; Lukich, Vasa; Chazan, Michael

    2014-01-01

    Kathu Townlands is a high density Earlier Stone Age locality in the Northern Cape Province, South Africa. Here we present the first detailed information on this locality based on analysis of a sample of lithic material from excavations by P. Beaumont and field observations made in the course of fieldwork in 2013. The results confirm the remarkably high artefact density at Kathu Townlands and do not provide evidence consistent with high energy transport as a mechanism of site formation, suggesting that Kathu Townlands was the site of intensive exploitation of highly siliceous outcroppings of banded iron formation. The results presented here provide a first step towards understanding this complex locality and point to the need for further research and the importance of preserving this locality in the face of intensive and rapid development. PMID:25058317

  9. Earlier testing for HIV--how do we prevent late presentation?

    PubMed

    Yazdanpanah, Yazdan; Lange, Joep; Gerstoft, Jan; Cairns, Gus

    2010-01-01

    HIV testing policies and practices vary widely across Europe. It is clear that there are individuals who might present late for HIV diagnosis and care within all risk groups, and potentially in any healthcare setting. This article explores the need to ensure earlier identification and treatment of late-presenting patients by reviewing strategies that might be considered. Such strategies could include routine provider-initiated HIV testing of at-risk groups in settings such as sexually transmitted infection clinics, drug dependency programmes or antenatal care. Healthcare providers might also consider routine HIV testing in all healthcare facilities, in settings including emergency and primary care, where local HIV prevalence is above a threshold that should be further evaluated. They should also take advantage of rapid testing technologies and be aware of barriers to HIV testing among specific groups to provide opportunities for testing that are relevant to local communities. PMID:20442457

  10. Earlier onset of the spring fine dust season in the southwestern United States

    NASA Astrophysics Data System (ADS)

    Hand, J. L.; White, W. H.; Gebhart, K. A.; Hyslop, N. P.; Gill, T. E.; Schichtel, B. A.

    2016-04-01

    Particulate matter (PM)2.5 dust concentrations (mineral particles with aerodynamic diameters less than 2.5 µm) typically peak in spring and early summer at rural and remote sites across the southwestern United States. Trend analyses indicate that springtime regional mean PM2.5 dust concentrations have increased from 1995 to 2014, especially in March (5.4% yr-1, p < 0.01). This increase reflects an earlier onset of the spring dust season across the Southwest by 1 to 2 weeks over the 20 year time period. March dust concentrations were strongly correlated with the Pacific Decadal Oscillation index (r = -0.65, p < 0.01), which was mostly in its negative phase from 2007 to 2014, during which the region was drier, windier, and less vegetated. The positive spring trend and its association with large-scale climate variability have several important implications for visibility, particulate matter, health effects, and the hydrologic cycle in the region.

  11. Climate dynamics from 17 to 7 kyr BP deduced from a new pollen record from Tenaghi Philippon in comparison with marine palynological data from the northern Aegean Sea

    NASA Astrophysics Data System (ADS)

    Kotthoff, U.; Pross, J.; Müller, U. C.; Dormoy, I.; Peyron, O.; Bordon, A.; Schmiedl, G.

    2009-04-01

    The time interval from 17 to 7 kyr BP is characterized by pronounced climate variability. Among the climatic setbacks during that time, the most prominent are the Younger Dryas (YD) and the 8.2 ka event. The impact of these setbacks on vegetation development is relatively well understood for higher-latitude settings particularly in Central and SW Europe. However, there is still a lack of high-resolution vegetation and climate data for the eastern Mediterranean region, although this region is an ideal natural laboratory for analyzing the effects of short-term climatic change on terrestrial environments due to its intermediate position between the higher-latitude and lower-latitude climate systems. In light of the above, we used a terrestrial core from Tenaghi Philippon, NE Greece, to carry out pollen-based vegetation and climate reconstructions. These indicate that both temperature and precipitation controlled vegetation dynamics until ~15 kyr BP. Between ~15 and ~12.7 kyr BP, temperatures were already comparable to early Holocene circumstances, thus changes in moisture availability appear to have been of major importance. During the interstadials of the Bølling/Allerød interstadial complex (BAC), moisture availability appears higher at Tenaghi Phillipon than during the preceding interval. The following Younger Dryas, although drier and colder than the preceding interstadials of the BAC, appears more humid/warmer than the preceding cold intervals, i.e. the Older and Oldest Dryas and the Pleniglacial. These results are in opposite to findings from a neighbouring marine palynomorph record, where the YD appears to be the coldest/driest interval between 17 and 7 kyr BP, implied by both pollen- and dinocyst-based reconstructions. The early Holocene was punctuated by several short-term climate events. Among these, the North-Atlantic-related 8.2 ka event is most strongly pronounced at Tenaghi Philippon, with winter temperatures declining by almost 4° C, in opposite to

  12. Evidence for Mid-latitude Lake-level Response to Millennial and Milankovitch Forcing: The Past 65 kyr at Mono Lake, CA

    NASA Astrophysics Data System (ADS)

    Zimmerman, S. H.; Hemming, S. R.; Hemming, N. G.; Pearl, C.; Hartin, C.

    2007-12-01

    Mono Lake, California (38°N, 119°W) lies in the western Great Basin in the rain shadow of the Sierra Nevada, and preserves high-elevation strandlines indicating that lake level was much higher in the past. Comparison of stratigraphy-based relative lake level with geochemical records from three sites around the lake (overlapping between 40-32 ka), reveals high carbonate fluxes at times of high lake level on precessional (20-kyr) time-scales. Although absolute values are different in different locations representing slightly different paleoenvironmental settings, the timing and relative amplitude of changes are similar on orbital as well as millennial time-scales. Within the established regional 100-kyr pattern of wet glacials-dry interglacials, we find that during the last glaciation (Marine Isotope Stages (MIS) 4-3-2) times of high spring insolation were generally wetter, represented by lacustrine silts rather than sand facies and greater carbonate flux to the deep-lake sediments. This interval is also characterized by high-amplitude variability. Age model errors of ~1 kyr or less during MIS 3 allow correlation of sharp increases in carbonate deposition with Dansgaard-Oeschger warmings in Greenland. If the high carbonate-high lake relationship holds at millennial time-scales, this would indicate increases in lake level coeval with warming, opposite to the 100-kyr regional pattern. Alternatively, carbonate precipitation may be triggered by lake level peaking and beginning to drop, suggesting that lake level began to fall about the time of Greenland warming. Regardless, the correspondence in phasing between Mono Lake and Greenland, also demonstrated in the nearby Santa Barbara Basin, suggests that Mono Lake responded rapidly to the atmosphere-ocean changes invoked to explain the global nature of the D-O events. The suppression of this variability during times of low spring insolation may be due to a reduced sensitivity of the recorder, and we are looking for

  13. Nd isotopic composition from seawater and sediments of the South China Sea and the Philippine Sea : implications for hydrology of the Pacific Ocean during the last 25 kyr

    NASA Astrophysics Data System (ADS)

    Wu, Qiong; Colin, Christophe; Liu, Zhifei; Thil, Francois; Douville, Eric; Frank, Norbert

    2014-05-01

    Nd isotopic compositions (ɛNd) of foraminifera from one gravity core (MD05-2904; 19°27.32' 116°15.15', 2066 m water depth) and 10 seawater profiles from the northern South China Sea (SCS) and the Philippine Sea (western Pacific Ocean) were measured to (1) constrain the Nd isotopic composition of water masses along the western Pacific and the SCS that are still poorly documented ; (2) track hydrological exchange between the SCS and western Pacific trough the Luzon strait ; (3) to test the ability of foraminifera to establish seawater ɛNd ; (4) to establish past hydrological changes of deep-water circulation in the western Pacific Ocean during the last 25 kyr. Distribution of ɛNd seawater of the Northern SCS and west Pacific indicate that the SCS is dominated by three water masses, the South China Sea Tropical Water (SCSTW) (~-7.7), South China Sea Intermediate Water (SCSIW) (~-3.6) and the Pacific Deep Water (PDW) (~-4). Our results indicate that at present time ɛNd of deep and intermediate waters of the SCS is representative of the PDW. Different analytical procedures to extract seawater ɛNd from foraminiferas (benthic and planktonic) and Fe-Mn coatings precipitated on the sediments have been tested and permit to determine that only ɛNd obtained from foraminiferas are reliable to seawater ɛNd in the South China Sea. A first record of past seawater ɛNd obtained from foraminifera of the core MD05-2904 (northern part of the SCS) indicate major change of the hydrology of the West Pacific during the last 25 kyr. ɛNd values variations indicate two negative excursion during at Heinrich Stadial 1(~16 kyr BP) and ~10 kyr BP implying a reorganization of the deep circulation in the Pacific. Such results are compared with other proxies of deep-water circulation to propose new insight in the role of the southern deep-water pacific circulation on climate during the last deglaciation.

  14. Earlier migration timing, decreasing phenotypic variation, and biocomplexity in multiple salmonid species.

    PubMed

    Kovach, Ryan P; Joyce, John E; Echave, Jesse D; Lindberg, Mark S; Tallmon, David A

    2013-01-01

    Climate-induced phenological shifts can influence population, evolutionary, and ecological dynamics, but our understanding of these phenomena is hampered by a lack of long-term demographic data. We use a multi-decade census of 5 salmonid species representing 14 life histories in a warming Alaskan stream to address the following key questions about climate change and phenology: How consistent are temporal patterns and drivers of phenology for similar species and alternative life histories? Are shifts in phenology associated with changes in phenotypic variation? How do phenological changes influence the availability of resource subsidies? For most salmonid species, life stages, and life histories, freshwater temperature influences migration timing--migration events are occurring earlier in time (mean = 1.7 days earlier per decade over the 3-5 decades), and the number of days over which migration events occur is decreasing (mean = 1.5 days per decade). Temporal trends in migration timing were not correlated with changes in intra-annual phenotypic variation, suggesting that these components of the phenotypic distribution have responded to environmental change independently. Despite commonalities across species and life histories, there was important biocomplexity in the form of disparate shifts in migration timing and variation in the environmental factors influencing migration timing for alternative life history strategies in the same population. Overall, adult populations have been stable during these phenotypic and environmental changes (λ ≈ 1.0), but the temporal availability of salmon as a resource in freshwater has decreased by nearly 30 days since 1971 due to changes in the median date of migration timing and decreases in intra-annual variation in migration timing. These novel observations advance our understanding of phenological change in response to climate warming, and indicate that climate change has influenced the ecology of salmon populations

  15. Patient- and system-related barriers for the earlier diagnosis of colorectal cancer

    PubMed Central

    Wahls, Terry L; Peleg, Ika

    2009-01-01

    Background A cohort of colorectal cancer (CRC) patients represents an opportunity to study missed opportunities for earlier diagnosis. Primary objective: To study the epidemiology of diagnostic delays and failures to offer/complete CRC screening. Secondary objective: To identify system- and patient-related factors that may contribute to diagnostic delays or failures to offer/complete CRC screening. Methods Setting: Rural Veterans Administration (VA) Healthcare system. Participants: CRC cases diagnosed within the VA between 1/1/2000 and 3/1/2007. Data sources: progress notes, orders, and pathology, laboratory, and imaging results obtained between 1/1/1995 and 12/31/2007. Completed CRC screening was defined as a fecal occult blood test or flexible sigmoidoscopy (both within five years), or colonoscopy (within 10 years); delayed diagnosis was defined as a gap of more than six months between an abnormal test result and evidence of clinician response. A summary abstract of the antecedent clinical care for each patient was created by a certified gastroenterologist (GI), who jointly reviewed and coded the abstracts with a general internist (TW). Results The study population consisted of 150 CRC cases that met the inclusion criteria. The mean age was 69.04 (range 35-91); 99 (66%) were diagnosed due to symptoms; 61 cases (46%) had delays associated with system factors; of them, 57 (38% of the total) had delayed responses to abnormal findings. Fifteen of the cases (10%) had prompt symptom evaluations but received no CRC screening; no patient factors were identified as potentially contributing to the failure to screen/offer to screen. In total, 97 (65%) of the cases had missed opportunities for early diagnosis and 57 (38%) had patient factors that likely contributed to the diagnostic delay or apparent failure to screen/offer to screen. Conclusion Missed opportunities for earlier CRC diagnosis were frequent. Additional studies of clinical data management, focusing on following

  16. The MEST score provides earlier risk prediction in lgA nephropathy.

    PubMed

    Barbour, Sean J; Espino-Hernandez, Gabriela; Reich, Heather N; Coppo, Rosanna; Roberts, Ian S D; Feehally, John; Herzenberg, Andrew M; Cattran, Daniel C

    2016-01-01

    The Oxford Classification of IgA nephropathy (IgAN) includes the following four histologic components: mesangial (M) and endocapillary (E) hypercellularity, segmental sclerosis (S) and interstitial fibrosis/tubular atrophy (T). These combine to form the MEST score and are independently associated with renal outcome. Current prediction and risk stratification in IgAN requires clinical data over 2 years of follow-up. Using modern prediction tools, we examined whether combining MEST with cross-sectional clinical data at biopsy provides earlier risk prediction in IgAN than current best methods that use 2 years of follow-up data. We used a cohort of 901 adults with IgAN from the Oxford derivation and North American validation studies and the VALIGA study followed for a median of 5.6 years to analyze the primary outcome (50% decrease in eGFR or ESRD) using Cox regression models. Covariates of clinical data at biopsy (eGFR, proteinuria, MAP) with or without MEST, and then 2-year clinical data alone (2-year average of proteinuria/MAP, eGFR at biopsy) were considered. There was significant improvement in prediction by adding MEST to clinical data at biopsy. The combination predicted the outcome as well as the 2-year clinical data alone, with comparable calibration curves. This effect did not change in subgroups treated or not with RAS blockade or immunosuppression. Thus, combining the MEST score with cross-sectional clinical data at biopsy provides earlier risk prediction in IgAN than our current best methods. PMID:26759049

  17. Midlife adiposity predicts earlier onset of Alzheimer's dementia, neuropathology and presymptomatic cerebral amyloid accumulation.

    PubMed

    Chuang, Y-F; An, Y; Bilgel, M; Wong, D F; Troncoso, J C; O'Brien, R J; Breitner, J C; Ferruci, L; Resnick, S M; Thambisetty, M

    2016-07-01

    Understanding how midlife risk factors influence age at onset (AAO) of Alzheimer's disease (AD) may provide clues to delay disease expression. Although midlife adiposity predicts increased incidence of AD, it is unclear whether it affects AAO and severity of Alzheimer's neuropathology. Using a prospective population-based cohort, Baltimore Longitudinal Study of Aging (BLSA), this study aims to examine the relationships between midlife body mass index (BMI) and (1) AAO of AD (2) severity of Alzheimer's neuropathology and (3) fibrillar brain amyloid deposition during aging. We analyzed data on 1394 cognitively normal individuals at baseline (8643 visits; average follow-up interval 13.9 years), among whom 142 participants developed incident AD. In two subsamples of BLSA, 191 participants underwent autopsy and neuropathological assessment, and 75 non-demented individuals underwent brain amyloid imaging. Midlife adiposity was derived from BMI data at 50 years of age. We find that each unit increase in midlife BMI predicts earlier onset of AD by 6.7 months (P=0.013). Higher midlife BMI was associated with greater Braak neurofibrillary but not CERAD (Consortium to Establish a Registry for Alzheimer's Disease) neuritic plaque scores at autopsy overall. Associations between midlife BMI and brain amyloid burden approached statistical significance. Thus, higher midlife BMI was also associated with greater fibrillar amyloid measured by global mean cortical distribution volume ratio (P=0.075) and within the precuneus (left, P=0.061; right, P=0.079). In conclusion, midlife overweight predicts earlier onset of AD and greater burden of Alzheimer's neuropathology. A healthy BMI at midlife may delay the onset of AD. PMID:26324099

  18. Grain-size based sea-level reconstruction in the south Bohai Sea during the past 135 kyr

    NASA Astrophysics Data System (ADS)

    Yi, Liang; Chen, Yanping

    2013-04-01

    marine surface and core samples, and to quantitatively reconstruct sea-level variation since the late Pleistocene in the south Bohai Sea, China. New insights into regional relative sea-level changes since the late Pleistocene are obtained (Yi et al., 2012): (1) The grain size of surface and core samples can be mathematically partitioned using the Weibull distribution into four components. These four components with differing modal sizes and percentages could be interpreted as a long-term suspension component, which only settles under low turbulence conditions, sortable silt and very fine sand components transported by suspension during greater turbulence and bedload transport component, respectively. (2) Through regression and rigorous verification techniques, the reference water level could be reconstructed from sediment grain size. The reconstruction quantitatively extends the regional relative sea-level history to the late Pleistocene, providing a comparatively long dataset to evaluate regional sea-level variability. (3) We find no evidence of a sea-level high stand during MIS3 but rather a substantial regression during 70-30 cal kyr BP and potentially exposed land during 38-20 cal kyr BP. These results for the south Bohai Sea are in good agreement with published global sea-level records for the late Pleistocene, implying similarities between local and global sea-level patterns. Therefore, it is concluded that grain-size based sea-level reconstruction provide results that are comparable to other reconstruction methods and demonstrates great potential application for future works. (The data was shared on http://hurricane.ncdc.noaa.gov/) References Chappell, J., Omura, A., Esat, T., McCulloch, M., Pandolfi, J., Ota, Y., Pillans, B., 1996. Reconciliation of late Quaternary sea levels derived from coral terraces at Huon Peninsula with deep sea oxygen isotope records. Earth and Planetary Science Letters 141, 227-236. Chappell, J., Shackleton, N.J., 1986. Oxygen isotopes

  19. Low forced expiratory volume is associated with earlier death in sickle cell anemia.

    PubMed

    Kassim, Adetola A; Payne, Amanda B; Rodeghier, Mark; Macklin, Eric A; Strunk, Robert C; DeBaun, Michael R

    2015-09-24

    Pulmonary complications result in mortality in adults with sickle cell anemia (SCA). We tested the hypothesis that abnormal pulmonary function was associated with earlier death. A prospective cohort of adults with SCA, followed in the Cooperative Study for Sickle Cell Disease, was constructed using the first pulmonary function test at >21 years of age. Spirometry measures: forced expiratory volume in 1 second (FEV1), forced vital capacity, and total lung capacity were categorized based on age, gender, height, and race. Pulmonary function patterns were categorized based on the American Thoracic Society guidelines using both spirometry and lung volumes. A cohort of 430 adults with SCA, mean age 32.6 ± 9.5 (range, 21.0-67.8) years at time of first pulmonary function test, and a median follow-up of 5.5 years, was evaluated. A total of 63 deaths occurred. At baseline, 47% had normal, 29% restrictive, 8% obstructive, 2% mixed, and 14% nonspecific lung function patterns. In the final multivariable model, lower FEV1 percent predicted was associated with increased hazard ratio of death (HR per % predicted 1.02; 95% confidence interval [CI] 1.00-1.04; P = .037), as was older age (HR 1.07; 95% CI 1.04-1.10; P < .001), male sex (HR 2.09; 95% CI 1.20-3.65; P = .010), higher lactate dehydrogenase levels (HR per mg/dL 1.002; 95% CI 1.00-1.003; P = .015), and higher acute chest syndrome incidence rate (HR per event/year 10.4; 95% CI 3.11-34.8; P < .001). Presence of obstructive (HR 1.18; 95% CI: 0.44-3.20; P = .740) and restrictive (HR 1.31; 95% CI: 0.64-2.32; P = .557) pulmonary function patterns were not associated with earlier death. Understanding the pathophysiology of a low FEV1 percent predicted in individuals with SCA is warranted, enabling early intervention for those at risk. PMID:26261241

  20. Quantifying the Economic Value and Quality of Life Impact of Earlier Influenza Vaccination

    PubMed Central

    Lee, Bruce Y.; Bartsch, Sarah M.; Brown, Shawn T.; Cooley, Philip; Wheaton, William D.; Zimmerman, Richard K.

    2015-01-01

    Background Influenza vaccination is administered throughout the influenza disease season, even as late as March. Given such timing, what is the value of vaccinating the population earlier than currently being practiced? Methods We used real data on when individuals were vaccinated in Allegheny County, Pennsylvania, and the following 2 models to determine the value of vaccinating individuals earlier (by the end of September, October, and November): Framework for Reconstructing Epidemiological Dynamics (FRED), an agent-based model (ABM), and FluEcon, our influenza economic model that translates cases from the ABM to outcomes and costs [health care and lost productivity costs and quality-adjusted life-years (QALYs)]. We varied the reproductive number (R0) from 1.2 to 1.6. Results Applying the current timing of vaccinations averted 223,761 influenza cases, $16.3 million in direct health care costs, $50.0 million in productivity losses, and 804 in QALYs, compared with no vaccination (February peak, R0 1.2). When the population does not have preexisting immunity and the influenza season peaks in February (R0 1.2–1.6), moving individuals who currently received the vaccine after September to the end of September could avert an additional 9634–17,794 influenza cases, $0.6–$1.4 million in direct costs, $2.1–$4.0 million in productivity losses, and 35–64 QALYs. Moving the vaccination of just children to September (R0 1.2–1.6) averted 11,366–1660 influenza cases, $0.6–$0.03 million in direct costs, $2.3–$0.2 million in productivity losses, and 42–8 QALYs. Moving the season peak to December increased these benefits, whereas increasing preexisting immunity reduced these benefits. Conclusion Even though many people are vaccinated well after September/October, they likely are still vaccinated early enough to provide substantial cost-savings. PMID:25590676

  1. An 80 kyr-long continuous speleothem record from Dim Cave, SW Turkey with paleoclimatic implications for the Eastern Mediterranean.

    PubMed

    Ünal-İmer, Ezgi; Shulmeister, James; Zhao, Jian-Xin; Uysal, I Tonguç; Feng, Yue-Xing; Nguyen, Ai Duc; Yüce, Galip

    2015-01-01

    Speleothem-based stable isotope records are valuable in sub-humid and semi-arid settings where many other terrestrial climate proxies are fragmentary. The Eastern Mediterranean is one such region. Here we present an 80-kyr-long precisely-dated (by U-series) and high-resolution oxygen (δ(18)O) and carbon (δ(13)C) records from Dim Cave (~36°N) in SW Turkey. The glacial-interglacial δ(18)O variations in the Dim Cave speleothem are best explained in terms of changes in the trajectories of winter westerly air masses. These are along a northerly (European) track (isotopically less depleted) during the early last glaciation but are gradually depressed southward closer to the modern westerly track along the North African coast (more depleted) after c.50 kyr and remain in the southern track through the Last Glacial Maximum. The southward displacement of the westerly track reflects growth of the Fennoscandian ice sheet and its impact on westerly wind fields. Changes in δ(13)C are interpreted as reflecting soil organic matter composition and/or thickness. δ(13)C values are significantly more negative in interglacials reflecting active carbonic acid production in the soil and less negative in glacial times reflecting carbonate rock values. Several Heinrich events are recorded in the Dim record indicating intensification of westerly flow across this part of the EM. PMID:26337921

  2. A 300 kyr Record of Geomagnetic Excursions and Paleointensity From the Irminger Basin: Candidates for Mono Lake, Laschamp, Iceland Basin, Jamaica and Pringle Falls?

    NASA Astrophysics Data System (ADS)

    Channell, J. E.

    2004-12-01

    Sediments recovered at ODP Site 919, off east Greenland, record geomagnetic directional excursions at 33 ka and 40 ka (Mono Lake and Laschamp), and at 187 ka (Iceland Basin), 208 ka (Jamaica?) and at 220 ka (Pringle Falls). U-channel records are augmented by 1-cm discrete samples collected back-to-back alongside the u-channel troughs. Deconvolution of the u-channel records yields records that can be closely matched to the discrete sample data. The age-model based on planktic oxygen isotope data (St. John et al., Marine Geology, in press) is consistent with the relative paleointensity record and the recognition of Ash Layer 2 (55 ka). The results indicate that the Mono Lake and Laschamp excursions, and the Iceland Basin and Pringle Falls (and perhaps also Jamaica), are distinct excursions, rarely recorded together in individual stratigraphic sections. Why are they recorded at ODP Site 919? Mean sedimentation rates are 22 cm/kyr in MIS 3 where Mono Lake/Laschamp are recorded, but sedimentation rates do not appear to be especially high in MIS 7 (13 cm/kyr) where candidates for Iceland Basin/Jamaica/Pringle Falls are recorded.

  3. An 80 kyr-long continuous speleothem record from Dim Cave, SW Turkey with paleoclimatic implications for the Eastern Mediterranean

    PubMed Central

    Ünal-İmer, Ezgi; Shulmeister, James; Zhao, Jian-Xin; Tonguç Uysal, I.; Feng, Yue-Xing; Duc Nguyen, Ai; Yüce, Galip

    2015-01-01

    Speleothem-based stable isotope records are valuable in sub-humid and semi-arid settings where many other terrestrial climate proxies are fragmentary. The Eastern Mediterranean is one such region. Here we present an 80-kyr-long precisely-dated (by U-series) and high-resolution oxygen (δ18O) and carbon (δ13C) records from Dim Cave (~36°N) in SW Turkey. The glacial-interglacial δ18O variations in the Dim Cave speleothem are best explained in terms of changes in the trajectories of winter westerly air masses. These are along a northerly (European) track (isotopically less depleted) during the early last glaciation but are gradually depressed southward closer to the modern westerly track along the North African coast (more depleted) after c.50 kyr and remain in the southern track through the Last Glacial Maximum. The southward displacement of the westerly track reflects growth of the Fennoscandian ice sheet and its impact on westerly wind fields. Changes in δ13C are interpreted as reflecting soil organic matter composition and/or thickness. δ13C values are significantly more negative in interglacials reflecting active carbonic acid production in the soil and less negative in glacial times reflecting carbonate rock values. Several Heinrich events are recorded in the Dim record indicating intensification of westerly flow across this part of the EM. PMID:26337921

  4. Bulk and Compound-Specific Isotope Analysis of Long-Chain, n-alkanes From a 85-kyr Core From Lake Peten Itza, Guatemala

    NASA Astrophysics Data System (ADS)

    Mays, J. L.; Brenner, M.; Bush, M. B.; Correa, A.; Curtis, J. H.; Hodell, D. A.

    2007-12-01

    Drill cores obtained from Lake Petén Itzá, Guatemala, contain a ~85-kyr record of terrestrial climate from lowland Central America. Variations in sediment lithology suggest rapid changes in precipitation during the last glacial and deglacial periods. Previous work in nearby Lake Quexil demonstrated the utility of using the carbon isotopic compositions of leaf wax n-alkanes to infer changes in terrestrial vegetation (Huang et al., 2001). Here we report carbon isotopes of bulk organic and long-chain n-alkanes in 60 samples to reconstruct changes in the relative proportion of C3 and C4 biomass in the watershed under changing climate and atmospheric CO2 conditions during the past 85 kyrs. Compound-specific carbon isotope results are compared directly with pollen analysis from the same samples. Huang, Y., F.A. Street-Perrott, S.E. Metcalfe, M. Brenner, M. Moreland, and K.H. Freeman. 2001. Climate change as the dominant control on glacial-interglacial variations in C3 and C4 plant abundance. Science 293:1647-1651.

  5. Man the Fat Hunter: The Demise of Homo erectus and the Emergence of a New Hominin Lineage in the Middle Pleistocene (ca. 400 kyr) Levant

    PubMed Central

    Ben-Dor, Miki; Gopher, Avi; Hershkovitz, Israel; Barkai, Ran

    2011-01-01

    The worldwide association of H. erectus with elephants is well documented and so is the preference of humans for fat as a source of energy. We show that rather than a matter of preference, H. erectus in the Levant was dependent on both elephants and fat for his survival. The disappearance of elephants from the Levant some 400 kyr ago coincides with the appearance of a new and innovative local cultural complex – the Levantine Acheulo-Yabrudian and, as is evident from teeth recently found in the Acheulo-Yabrudian 400-200 kyr site of Qesem Cave, the replacement of H. erectus by a new hominin. We employ a bio-energetic model to present a hypothesis that the disappearance of the elephants, which created a need to hunt an increased number of smaller and faster animals while maintaining an adequate fat content in the diet, was the evolutionary drive behind the emergence of the lighter, more agile, and cognitively capable hominins. Qesem Cave thus provides a rare opportunity to study the mechanisms that underlie the emergence of our post-erectus ancestors, the fat hunters. PMID:22174868

  6. The cortical representation of the speech envelope is earlier for audiovisual speech than audio speech.

    PubMed

    Crosse, Michael J; Lalor, Edmund C

    2014-04-01

    Visual speech can greatly enhance a listener's comprehension of auditory speech when they are presented simultaneously. Efforts to determine the neural underpinnings of this phenomenon have been hampered by the limited temporal resolution of hemodynamic imaging and the fact that EEG and magnetoencephalographic data are usually analyzed in response to simple, discrete stimuli. Recent research has shown that neuronal activity in human auditory cortex tracks the envelope of natural speech. Here, we exploit this finding by estimating a linear forward-mapping between the speech envelope and EEG data and show that the latency at which the envelope of natural speech is represented in cortex is shortened by >10 ms when continuous audiovisual speech is presented compared with audio-only speech. In addition, we use a reverse-mapping approach to reconstruct an estimate of the speech stimulus from the EEG data and, by comparing the bimodal estimate with the sum of the unimodal estimates, find no evidence of any nonlinear additive effects in the audiovisual speech condition. These findings point to an underlying mechanism that could account for enhanced comprehension during audiovisual speech. Specifically, we hypothesize that low-level acoustic features that are temporally coherent with the preceding visual stream may be synthesized into a speech object at an earlier latency, which may provide an extended period of low-level processing before extraction of semantic information. PMID:24401714

  7. Motivation before meaning: motivational information encoded in meerkat alarm calls develops earlier than referential information.

    PubMed

    Hollén, Linda I; Manser, Marta B

    2007-06-01

    In contrast to historical assumptions about the affective nature of animal vocalizations, it is now clear that many vertebrates are capable of producing specific alarm calls in response to different predators, calls that provide information that goes beyond the motivational state of a caller. However, although these calls function referentially, it does not mean that they are devoid of motivational content. Studies on meerkats (Suricata suricatta) directly support this conclusion. The acoustic structure of their alarm calls simultaneously encodes information that is both motivational (level of urgency) and referential (predator specific). In this study, we investigated whether alarm calls of young meerkats undergo developmental modification and whether the motivational or the referential aspect of calls changes more over time. We found that, based on their acoustic structure, calls of young showed a high correct assignment to low- and high-urgency contexts but, in contrast to adults, low assignment to specific predator types. However, the discrimination among predator types was better in high-urgency than in low-urgency contexts. Our results suggest that acoustic features related to level of urgency are expressed earlier than those related to predator-specific information and may support the idea that referential calls evolve from motivational signals. PMID:17479462

  8. A bioresorbable osteosynthesis device can induce an earlier sternal fusion after median sternotomy

    PubMed Central

    Tsunekawa, Tomohiro; Usui, Akihiko; Oshima, Hideki; Mizutani, Shinnichi; Araki, Yoshimori; Okada, Noritaka; Ueda, Yuichi

    2012-01-01

    OBJECTIVES We examined the impact of the bioresorbable osteosynthesis sternal pin (Super Fixsorb 30) on sternal healing after median sternotomy. METHODS Sixty-three patients who underwent aortic surgery through median sternotomy between January 2006 and March 2009 were analysed. Sternal pins were utilized in 36 patients in addition to the standard closure of the sternum with Ethibond sutures (Group A), and 27 patients received no pins with the standard Ethibond sternal closure (Group B). The occurrence of transverse sternal dehiscence, anterior–posterior displacement and complete fusion of the sternum were evaluated by a computed tomography scan. The cross-sectional cortical bone density area (CBDA) of the sternum was examined to evaluate the osteoconductivity of the sternal pin over a 12-month period. RESULTS There was no sternal displacement (0%) observed in Group A at discharge. Meanwhile, five displacements (18.5%) were observed in Group B (P = 0.007). The complete sternal fusion rates at 12 months postoperatively were 100% in Group A, and 21.6% in Group B (P < 0.001). A significant increase in the CBDA was observed in Group A (P < 0.001; between CBDA at discharge and 12 months postoperatively). CONCLUSIONS The Super Fixsorb 30 sternal pin reduced an anterior–posterior sternal displacement and facilitated an earlier sternal fusion. The pin may have the potential to promote osteogenesis. PMID:22623628

  9. Change in the Cortical Complexity of Spinocerebellar Ataxia Type 3 Appears Earlier than Clinical Symptoms

    PubMed Central

    Soong, Bing-Wen; Wu, Hsiu-Mei; Shyu, Kuo-Kai; Wang, Po-Shan; Wu, Yu-Te

    2015-01-01

    Patients with spinocerebellar ataxia type 3 (SCA3) have exhibited cerebral cortical involvement and various mental deficits in previous studies. Clinically, conventional measurements, such as the Mini-Mental State Examination (MMSE) and electroencephalography (EEG), are insensitive to cerebral cortical involvement and mental deficits associated with SCA3, particularly at the early stage of the disease. We applied a three-dimensional fractal dimension (3D-FD) method, which can be used to quantify the shape complexity of cortical folding, in assessing cortical degeneration. We evaluated 48 genetically confirmed SCA3 patients by employing clinical scales and magnetic resonance imaging and using 50 healthy participants as a control group. According to the Scale for the Assessment and Rating of Ataxia (SARA), the SCA3 patients were diagnosed with cortical dysfunction in the cerebellar cortex; however, no significant difference in the cerebral cortex was observed according to the patients’ MMSE ratings. Using the 3D-FD method, we determined that cortical involvement was more extensive than involvement of traditional olivopontocerebellar regions and the corticocerebellar system. Moreover, the significant correlation between decreased 3D-FD values and disease duration may indicate atrophy of the cerebellar cortex and cerebral cortex in SCA3 patients. The change of the cerebral complexity in the SCA3 patients can be detected throughout the disease duration, especially it becomes substantial at the late stage of the disease. Furthermore, we determined that atrophy of the cerebral cortex may occur earlier than changes in MMSE scores and EEG signals. PMID:25897782

  10. Earlier onset of motor deficits in mice with double mutations in Dyt1 and Sgce

    PubMed Central

    Yokoi, Fumiaki; Yang, Guang; Li, JinDong; DeAndrade, Mark P.; Zhou, Tong; Li, Yuqing

    2010-01-01

    DYT1 early-onset generalized torsion dystonia is an inherited movement disorder caused by mutations in DYT1 coding for torsinA with ∼30% penetrance. Most of the DYT1 dystonia patients exhibit symptoms during childhood and adolescence. On the other hand, DYT1 mutation carriers without symptoms during these periods mostly do not exhibit symptoms later in their life. Little is known about what controls the timing of the onset, a critical issue for DYT1 mutation carriers. DYT11 myoclonus-dystonia is caused by mutations in SGCE coding for ε-sarcoglycan. Two dystonia patients from a single family with double mutations in DYT1 and SGCE exhibited more severe symptoms. A recent study suggested that torsinA contributes to the quality control of ε-sarcoglycan. Here, we derived mice carrying mutations in both Dyt1 and Sgce and found that these double mutant mice showed earlier onset of motor deficits in beam-walking test. A novel monoclonal antibody against mouse ε-sarcoglycan was developed by using Sgce knock-out mice to avoid the immune tolerance. Western blot analysis suggested that functional deficits of torsinA and ε-sarcoglycan may independently cause motor deficits. Examining additional mutations in other dystonia genes may be beneficial to predict the onset in DYT1 mutation carriers. PMID:20627944

  11. Towards earlier inclusion of Children in Tuberculosis (TB) drugs trials: Consensus statements from an Expert Panel

    PubMed Central

    Nachman, Sharon; Ahmed, Amina; Amanullah, Farhana; Becerra, Mercedes C; Botgros, Radu; Brigden, Grania; Browning, Renee; Gardiner, Elizabeth; Hafner, Richard; Hesseling, Anneke; How, Cleotilde; Jean-Philippe, Patrick; Lessem, Erica; Makhene, Mamodikoe; Mbelle, Nontombi; Marais, Ben; McIlleron, Helen; Mc Neeley, David F; Mendel, Carl; Murray, Stephen; Navarro, Eileen; Oramasionwu, Gloria E; Porcalla, Ariel R; Powell, Clydette; Powell, Mair; Rigaud, Mona; Rouzier, Vanessa; Samson, Pearl; Schaaf, H. Simon; Shah, Seema; Starke, Jeff; Swaminathan, Soumya; Wobudeya, Eric; Worrell, Carol

    2015-01-01

    Children represent a significant proportion of the global tuberculosis (TB) burden, and may be disproportionately more affected by its most severe clinical manifestations. Currently available treatments for pediatric drug-susceptible (DS) and drug-resistant (DR) TB, albeit generally effective, are hampered by high pill burden, long duration of treatment, coexistent toxicities, and an overall lack of suitable, child-friendly formulations. The complex and burdensome nature of administering the existing regimens to treat DS TB also contributes to the rise of DR TB strains. Despite the availability and use of these therapies for decades, a dearth of dosing evidence in children underscores the importance of sustained efforts for TB drug development to better meet the treatment needs of children with TB. Several new TB drugs and regimens with promising activity against both DS and DR TB strains have recently entered clinical development and are in various phases of clinical evaluation in adults or have received marketing authorization for adults. However, initiation of clinical trials to evaluate these drugs in children is often deferred, pending the availability of complete safety and efficacy data in adults or after drug approval. This document summarizes consensus statements from an international panel of childhood TB opinion leaders which support the initiation of evaluation of new TB drugs and regimens in children at earlier phases of the TB Drug development cycle. PMID:25957923

  12. The response of aboveground plant productivity to earlier snowmelt and summer warming in an Arctic ecosystem

    NASA Astrophysics Data System (ADS)

    Livensperger, C.; Steltzer, H.; Darrouzet-Nardi, A.; Sullivan, P.; Wallenstein, M. D.; Weintraub, M. N.

    2012-12-01

    Plant communities in the Arctic are undergoing changes in structure and function due to shifts in seasonality from changing winters and summer warming. These changes will impact biogeochemical cycling, surface energy balance, and functioning of vertebrate and invertebrate communities. To examine seasonal controls on aboveground net primary production (ANPP) in a moist acidic tundra ecosystem in northern Alaska, we shifted the growing season by accelerating snowmelt (using radiation absorbing shadecloth) and warming air and soil temperature (using 1 m2 open-top chambers), individually and in combination. After three years, we measured ANPP by harvesting up to 16 individual ramets, tillers and rhizomes for each of 7 plant species, including two deciduous shrubs, two graminoids, two evergreen shrubs and one forb during peak season. Our results show that ANPP per stem summed across the 7 species increased when snow melt occurred earlier. However, standing biomass, excluding current year growth, was also greater. The ratio of ANPP/standing biomass decreased in all treatments compared to the control. ANPP per unit standing biomass summed for the four shrub species decreases due to summer warming alone or in combination with early snowmelt; however early snowmelt alone did not lead to lower ANPP for the shrubs. ANPP per tiller or rhizome summed for the three herbaceous species increased in response to summer warming. Understanding the differential response of plants to changing seasonality will inform predictions of future Arctic plant community structure and function.

  13. Earlier springs are causing reduced nitrogen availability in North American eastern deciduous forests.

    PubMed

    Elmore, Andrew J; Nelson, David M; Craine, Joseph M

    2016-01-01

    There is wide agreement that anthropogenic climate warming has influenced the phenology of forests during the late twentieth and early twenty-first centuries(1,2). Longer growing seasons can lead to increased photosynthesis and productivity(3), which would represent a negative feedback to rising CO2 and consequently warming(4,5). Alternatively, increased demand for soil resources because of a longer photosynthetically active period in conjunction with other global change factors might exacerbate resource limitation(6,7), restricting forest productivity response to a longer growing season(8,9). In this case, increased springtime productivity has the potential to increase plant nitrogen limitation by increasing plant demand for nitrogen more than nitrogen supplies, or increasing early-season ecosystem nitrogen losses(10,11). Here we show that for 222 trees representing three species in eastern North America earlier spring phenology during the past 30 years has caused declines in nitrogen availability to trees by increasing demand for nitrogen relative to supply. The observed decline in nitrogen availability is not associated with reduced wood production, suggesting that other environmental changes such as increased atmospheric CO2 and water availability are likely to have overwhelmed reduced nitrogen availability. Given current trajectories of environmental changes, nitrogen limitation is likely to continue to increase for these forests, possibly further limiting carbon sequestration potential. PMID:27618399

  14. Excitable dendrites and spines: earlier theoretical insights elucidate recent direct observations.

    PubMed

    Segev, I; Rall, W

    1998-11-01

    Important advances in experimental methods have made it possible to measure the electrical events in dendrites directly and to record optically from dendritic spines. These new techniques allow us to focus on the input region of the neuron and highlight the excitable properties of the dendritic membrane. Interestingly, some of the recent experimental findings were anticipated by earlier theoretical research, for example, the observation that some spines possess excitable channels that might generate local all-or-none events. Computer models were used previously to explore the conditions for initiating an action potential at the dendritic tree, in particular, at the spine head, and for active propagation between excitable spines and excitable dendritic arbors. The consequences for synaptic amplification, for the extent of active spread in the tree and for non-linear discriminations between different patterns of synaptic inputs were also considered. Here we review the biophysical insights gained from the theory and demonstrate how these elucidate the recent experimental results. PMID:9829684

  15. Controlling Laser-Driven Hohlraums-Clues from Experiments with Earlier Lasers

    NASA Astrophysics Data System (ADS)

    Kruer, William; Thomas, Cliff

    2015-11-01

    Better characterized and controlled hohlraums are very important for both implosion and science experiments on NIF. A brief review of some hohlraum and related experiments with earlier lasers is given to search for lessons learned and clues for better understanding NIF hohlraums. For example, surprises associated with heat transport inhibition and improved models for radiation generation have been a recurring theme in indirect drive experiments. In Shiva experiments, the hohlraum filling with plasma with density near quarter-critical was only calculated after inhibited heat transport and improved radiation models were adopted in the design code. Early NIF experiments also led to a change in the heat transport and radiation models. In this case, the heat transport model was changed from one with modest inhibition (which had been used to model Nova experiments) to near classical transport. Most recently, a design model invoking very inhibited transport (at various times and locations) has been proposed by C. Thomas for NIF hohlraums. Other recurring themes will also be discussed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  16. Biogeochemistry of mineral-organic associations across a long-term mineralogical soil gradient (0.3-4100 kyr), Hawaiian Islands

    NASA Astrophysics Data System (ADS)

    Mikutta, Robert; Schaumann, Gabriele E.; Gildemeister, Daniela; Bonneville, Steeve; Kramer, Marc G.; Chorover, Jon; Chadwick, Oliver A.; Guggenberger, Georg

    2009-04-01

    Organic matter (OM) in mineral-organic associations (MOAs) represents a large fraction of carbon in terrestrial ecosystems which is considered stable against biodegradation. To assess the role of MOAs in carbon cycling, there is a need to better understand (i) the time-dependent biogeochemical evolution of MOAs in soil, (ii) the effect of the mineral composition on the physico-chemical properties of attached OM, and (iii) the resulting consequences for the stabilization of OM. We studied the development of MOAs across a mineralogical soil gradient (0.3-4100 kyr) at the Hawaiian Islands that derived from basaltic tephra under comparable climatic and hydrological regimes. Mineral-organic associations were characterized using biomarker analyses of OM with chemolytic methods (lignin phenols, non-cellulosic carbohydrates) and wet chemical extractions, surface area/porosity measurements (N 2 at 77 K and CO 2 at 273 K), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The results show that in the initial weathering stage (0.3 kyr), MOAs are mainly composed of primary, low-surface area minerals (olivine, pyroxene, feldspar) with small amounts of attached OM and lignin phenols but a large contribution of microbial-derived carbohydrates. As high-surface area, poorly crystalline (PC) minerals increase in abundance during the second weathering stage (20-400 kyr), the content of mineral-associated OM increased sharply, up to 290 mg C/g MOA, with lignin phenols being favored over carbohydrates in the association with minerals. In the third and final weathering stage (1400-4100 kyr), metastable PC phases transformed into well crystalline secondary Fe and Al (hydr)oxides and kaolin minerals that were associated with less OM overall, and depleted in both lignin and carbohydrate as a fraction of total OM. XPS, the N 2 pore volume data and OM-mineral volumetric ratios suggest that, in contrast to the

  17. Business Education Curriculum. Revised.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

    This revised curriculum gives information on the skills and knowledge students should acquire through a business education program. The competencies listed reflect the skills that employers see as necessary for success in clerical and accounting occupations. The handbook is organized in seven sections that cover the following: (1) the concept of…

  18. Revising the Institutional Mission.

    ERIC Educational Resources Information Center

    Dominick, Charles A.

    1990-01-01

    Revision of a college mission statement through a broadly participatory process can provide a new and sharpened sense of direction and priorities and a powerful mechanism for institutional change. Although institutional circumstances and processes may differ, the experience of Wittenberg University (Ohio) serves as an example of a model for…

  19. School Safety Handbook. Revised.

    ERIC Educational Resources Information Center

    Association of School Business Officials International, Reston, VA.

    The revised edition of this handbook represents a concerted effort to bring school safety to the forefront of business managers' daily and long-range planning activities. Although statistics show few fatalities on school grounds, schools appear to have a high frequency and incident rate of nonfatal injuries. According to the introduction, school…

  20. Overcoming Aspirin Resistance with Loading Clopidogrel Earlier in Elective Percutaneous Coronary Intervention

    PubMed Central

    Ozcan, Ozgur Ulas; Tutar, Eralp; Candemir, Basar; Ustun, Elif Ezgi; Erol, Cetin

    2015-01-01

    We aimed to analyze the clinical effect of clopidogrel loading time on adverse cardiovascular events among patients with aspirin resistance. Recurrent adverse events may still occur despite dual antiplatelet therapy after coronary stenting. Aspirin resistance is one of the possible reasons of this trouble. Optimal antiplatelet strategy for coronary stenting is unknown among patients with aspirin resistance. A total of 980 patients scheduled for elective coronary stenting were enrolled and allocated into two groups according to the loading time of clopidogrel more or less than 6 hours before coronary intervention (early- or late-loaded groups, respectively). Aspirin resistance was determined according to the urinary levels of 11-dehydrothromboxane B2. Overall 240 patients who were allocated to early- and late-loaded groups were identified as aspirin resistant according to the urinary levels of 11-dehydrothromboxane B2. After a follow-up period of 12 months major adverse cardiac events were observed among 16 patients (13.9%) in the early-loaded group and 30 patients (25.8%) in the late-loaded group (p = 0.02). Early loading of clopidogrel was an independent predictor of lower rate of cardiac events (hazard ratio = 0.46 [0.32–0.76, 95% confidence interval], p = 0.001). The rates of bleeding events and periprocedural myocardial infarction were similar in early- and late-loaded groups. The current study demonstrated that loading of clopidogrel earlier than 6 hours before elective coronary stenting among aspirin-resistant patients was associated with increased benefits for ischemic events with similar bleeding rates. PMID:25780324

  1. Earlier Menarche Is Associated with Lower Insulin Sensitivity and Increased Adiposity in Young Adult Women

    PubMed Central

    Wilson, Dyanne A.; Derraik, José G. B.; Rowe, Deborah L.; Hofman, Paul L.; Cutfield, Wayne S.

    2015-01-01

    Objective We aimed to assess whether age at menarche was associated with insulin sensitivity in young adult women. Methods We studied 54 healthy young women aged 20–30 years. Participants were grouped according to age at menarche: Early (≤11.0 years; n=13), Average (>12.0 and ≤13.0 years; n=28), and Late (≥14.0 years, n=13). Primary outcome was insulin sensitivity measured using intravenous glucose tolerance tests and Bergman’s minimal model. Body composition was assessed using whole-body dual-energy X-ray absorptiometry. Results Earlier menarche was associated with lower insulin sensitivity (p=0.015). There was also a continuous increase in adiposity with younger age at menarche, which was associated with increased weight (p=0.001), BMI (p=0.002), total body fat (p=0.049), and truncal fat (p=0.020). Stratified analyses showed that insulin sensitivity in Early women (5.5 x10-4·min-1(mU/l)) was lower than in Average (8.0 x10-4·min-1(mU/l), p=0.021) and Late (8.6 x10-4·min-1(mU/l), p=0.033) groups. Early women (weight=66.1 kg; BMI=24.1 kg/m2) were considerably heavier and fatter than Average (59.0 kg, p=0.004; 21.4 kg/m2, p=0.002) and Late (57.0 kg, p=0.001; 20.8 kg/m2, p=0.0009) women. Conclusions Early menarche is associated with lower insulin sensitivity and increased adiposity in young adulthood, potentially increasing the risk of type 2 diabetes and the metabolic syndrome later in life. PMID:26061526

  2. Selection for earlier flowering crop associated with climatic variations in the Sahel.

    PubMed

    Vigouroux, Yves; Mariac, Cédric; De Mita, Stéphane; Pham, Jean-Louis; Gérard, Bruno; Kapran, Issoufou; Sagnard, Fabrice; Deu, Monique; Chantereau, Jacques; Ali, Abdou; Ndjeunga, Jupiter; Luong, Viviane; Thuillet, Anne-Céline; Saïdou, Abdoul-Aziz; Bezançon, Gilles

    2011-01-01

    Climate changes will have an impact on food production and will require costly adaptive responses. Adapting to a changing environment will be particularly challenging in sub-Saharan Africa where climate change is expected to have a major impact. However, one important phenomenon that is often overlooked and is poorly documented is the ability of agro-systems to rapidly adapt to environmental variations. Such an adaptation could proceed by the adoption of new varieties or by the adaptation of varieties to a changing environment. In this study, we analyzed these two processes in one of the driest agro-ecosystems in Africa, the Sahel. We performed a detailed study in Niger where pearl millet is the main crop and covers 65% of the cultivated area. To assess how the agro-system is responding to recent recurrent drought, we analyzed samples of pearl millet landraces collected in the same villages in 1976 and 2003 throughout the entire cultivated area of Niger. We studied phenological and morphological differences in the 1976 and 2003 collections by comparing them over three cropping seasons in a common garden experiment. We found no major changes in the main cultivated varieties or in their genetic diversity. However, we observed a significant shift in adaptive traits. Compared to the 1976 samples, samples collected in 2003 displayed a shorter lifecycle, and a reduction in plant and spike size. We also found that an early flowering allele at the PHYC locus increased in frequency between 1976 and 2003. The increase exceeded the effect of drift and sampling, suggesting a direct effect of selection for earliness on this gene. We conclude that recurrent drought can lead to selection for earlier flowering in a major Sahelian crop. Surprisingly, these results suggest that diffusion of crop varieties is not the main driver of short term adaptation to climatic variation. PMID:21573243

  3. Warming Mountains, Earlier runoff and Declining Snowpack in Western North America

    NASA Astrophysics Data System (ADS)

    Cayan, D. R.

    2015-12-01

    Climate changes, which will very likely mount over the next several decades, would add to a set of shifts that have appeared in snow and runoff during recent decades over western North America. Water from mountain snow has historically provided a vital portion of the water supply for the region, but warming since the mid-1970's has produced more rain, less snow, diminished snow accumulation and earlier runoff over mountain catchments that historically have accumulated significant snow cover. The observed warming and the hydrologic shifts have, with a high degree of likelihood, been boosted by additional anthropogenic warming. A many-member ensemble of CMIP5 GCM simulations indicates that even under moderate scenarios of rising greenhouse gases, the warming, relative to historical climatology, could approach +2°C by mid-21st Century. This amount of warming would produce substantial changes in watersheds which have historically been dominated by snowmelt. In the California Sierra Nevada, this warming would advance spring runoff timing by more than two weeks. Combined with changes towards increased precipitation amounts in the region's largest storms, higher than present-day freezing levels would increase flood flows in Sierran rivers. Historical observations and hydrological model simulations indicate that California's total spring snow water storage will decline by more than half by 2100. Heavy snow years would still occur, but not as often as today, and springs with highly depleted mountain snow pack would occur with increasing frequency. These changes would produce a cascade of impacts to natural landscapes and resources, requiring multifold adaptation strategies by the humans who use and are affected by them.

  4. Newer drugs and earlier treatment: Impact on lifetime cost of care for HIV-infected adults

    PubMed Central

    Sloan, C.E.; Champenois, K.; Choisy, P.; Losina, E.; Walensky, R.P.; Schackmanj, B.R.; Ajana, F.; Melliez, H.; Paltiel, A.D.; Freedberg, K.A.

    2011-01-01

    Objective To determine the component costs of care to optimize treatment with limited resources. Design We used the Cost-Effectiveness of Preventing AIDS Complications Model of HIV disease and treatment to project life expectancy (LE) and both undiscounted and discounted lifetime costs (2010€). Methods We determined medical resource utilization among HIV-infected adults followed from 1998 to 2005 in Northern France. Monthly HIV costs were stratified by CD4 count. Costs of CD4, HIV RNA and genotype tests and antiretroviral therapy (ART) were derived from published literature. Model inputs from national data included mean age 38 years, mean initial CD4 count 372/µl, ART initiation at CD4 counts <350/µl, and ART regimen costs ranging from €760/month to €2,570/month. Results The model projected a mean undiscounted LE of 26.5 years and a lifetime undiscounted cost of €535,000/patient (€320,700 discounted); 73% of costs were ART-related. When patients presented to care with mean CD4 counts of 510/µl and initiated ART at CD4 counts <500/µl or HIV RNA >100,000 copies/ml, LE was 27.4 years and costs increased 1–2%, to €546,700 (€324,500 discounted). When we assumed introducing generic drugs would result in a 50% decline in first-line ART costs, lifetime costs decreased 4–6%, to €514,200 (€302,800 discounted). Conclusions As HIV disease is treated earlier with more efficacious drugs, survival and thus costs of care will continue to increase. The availability in high-income countries of widely-used antiretroviral drugs in generic form could reduce these costs. PMID:22008655

  5. Improving our understanding of flood forecasting using earlier hydro-meteorological intelligence

    NASA Astrophysics Data System (ADS)

    Shih, Dong-Sin; Chen, Cheng-Hsin; Yeh, Gour-Tsyh

    2014-05-01

    In recent decades, Taiwan has suffered from severe bouts of torrential rain, and typhoon induced floods have become the major natural threat to Taiwan. In order to warn the public of potential risks, authorities are considering establishing an early warning system derived from an integrated hydro-meteorological estimation process. This study aims at the development and accuracy of such a warning system. So it is first necessary to understand the distinctive features of flood forecasting in integrated rainfall-runoff simulations. Additionally the adequacies of a warning system that is based on extracting useful intelligence from earlier, possibly faulty numerical simulation results are discussed. In order to precisely model flooding, hydrological simulations based upon spot measured rainfall data have been utilized in prior studies to calibrate model parameters. Here, precipitation inputs from an ensemble of almost 20 different realizations of rainfall fields have been used to derive flood forecasts. The flood warning system therefore integrates rainfall-runoff calculations, field observations and data assimilations. Simulation results indicate that the ensemble precipitation estimates generated by a Weather Research Forecasting (WRF) mesoscale model produce divergent estimates. Considerable flooding is often shown in the simulated hydrographs, but the results as to the peak time and peak stage are not always in agreement with the observations. In brief, such forecasts can be good for warning against potential damaging floods in the near future, but the meteorological inputs are not good enough to forecast the time and magnitude of the peaks. The key for such warning system is not to expect highly accurate rainfall predictions, but to improve our understanding from individual ensemble flood forecasts.

  6. Toward an Earlier Diagnosis of Primary Ciliary Dyskinesia. Which Patients Should Undergo Detailed Diagnostic Testing?

    PubMed

    Kuehni, Claudia E; Lucas, Jane S

    2016-08-01

    Primary ciliary dyskinesia (PCD) is a rare, heterogeneous, recessive, genetic disorder of motile cilia, leading to chronic upper and lower respiratory symptoms. Prevalence is estimated at around 1:10,000, but many patients remain undiagnosed, whereas others receive the label incorrectly. Proper diagnosis is complicated by the fact that the key symptoms, such as wet cough, chronic rhinitis, and recurrent upper and lower respiratory infection, are common and nonspecific. There is no single gold standard test to diagnose PCD. Currently, the diagnosis is made in patients with a compatible medical history after a demanding combination of tests including nasal nitric oxide, high-speed video microscopy, and transmission electron microscopy and genetic and ciliary culture testing. These tests are costly and need sophisticated equipment and experienced staff, restricting use to highly specialized centers. Therefore, it would be desirable to have a screening test for identifying those patients who should undergo detailed diagnostic testing. Three recent studies focused on potential screening tools: one study assessed the validity of nasal nitric oxide for screening, and two studies developed new symptom-based screening tools. These simple tools are welcome, and it is hoped that they will assist physicians in determining whom to refer for definitive testing. However, they have been developed in tertiary care settings, where 10 to 50% of tested patients have PCD. The sensitivity and specificity of the tools are reasonable, but positive and negative predictive values may be poor in primary or secondary care settings. Although these studies are an important step toward an earlier diagnosis of PCD, more remains to be done before we have tools tailored to different health care settings. PMID:27258773

  7. NPH Log: Validation of a New Assessment Tool Leading to Earlier Diagnosis of Normal Pressure Hydrocephalus

    PubMed Central

    Lu, Jennifer; Robison, Jamie; Hoffberger, Jamie B; Hulbert, Alicia; Sanyal, Abanti; Wemmer, Jan; Elder, Benjamin D; Rigamonti, Daniele

    2016-01-01

    Introduction: Early treatment of normal pressure hydrocephalus (NPH) yields better postoperative outcomes. Our current tests often fail to detect significant changes at early stages. We developed a new scoring system (LP log score) to determine if this tool is more sensitive in detecting clinical differences than current tests. Material and Methods: Sixty-two consecutive new patients with suspected idiopathic NPH were studied. Secondary, previously treated and obstructive cases were not included. We collected age, pre- and post-lumbar puncture (LP) Tinetti, Timed Up and Go (TUG) Test, European NPH scale, and LP log scores. The LP log score is recorded at baseline and for seven consecutive days after removing 40 cc of cerebrospinal fluid (CSF) via LP. We studied the diagnostic accuracy of the tests for surgical indication. Results: The post-LP log showed improvement in 90% of people with good baseline gait tests and in 93% of people who did not show any pre-LP and post-LP change in gait tests. Sensitivity, specificity, and accuracy to detect intention to treat when positive post-LP improvements were 4%, 100%, and 24%, respectively, for TUG, 21%, 86%, and 34%, respectively, for the Tinetti Mobility Test, 66%, 29%, and 58%, respectively, for Medical College of Virginia (MCV) grade, and 98%, 33%, and 85%, respectively, for LP log score. Pre-LP and post-LP TUG improvement and pre-LP and post-LP Tinetti improvement were not associated with a surgical indication (p > 0.05). LP log improvement was associated with surgical indication odds ratio (OR): 24.5 95% CI (2.4-248.12) (p = 0.007). Conclusions: LP log showed better sensitivity, diagnostic accuracy, and association with surgical indication than the current diagnostic approach. An LP log may be useful detecting NPH patients at earlier stages and, therefore, yield better surgical outcomes. PMID:27489752

  8. Endoplasmic reticulum stress induced by zinc oxide nanoparticles is an earlier biomarker for nanotoxicological evaluation.

    PubMed

    Chen, Rui; Huo, Lingling; Shi, Xiaofei; Bai, Ru; Zhang, Zhenjiang; Zhao, Yuliang; Chang, Yanzhong; Chen, Chunying

    2014-03-25

    Zinc oxide nanoparticles (ZnO NPs) have been widely used in cosmetics and sunscreens, advanced textiles, self-charging and electronic devices; the potential for human exposure and the health impact at each stage of their manufacture and use are attracting great concerns. In addition to pulmonary damage, nanoparticle exposure is also strongly correlated with the increase in incidences of cardiovascular diseases; however, their toxic potential remains largely unclear. Herein, we investigated the cellular responses and endoplasmatic reticulum (ER) stress induced by ZnO NPs in human umbilical vein endothelial cells (HUVECs) in comparison with the Zn2+ ions and CeO2 NPs. We found that the dissolved zinc ion was the most significant factor for cytotoxicity in HUVECs. More importantly, ZnO NPs at noncytotoxic concentration, but not CeO2 NPs, can induce significant cellular ER stress response with higher expression of spliced xbp-1, chop, and caspase-12 at the mRNA level, and associated ER marker proteins including BiP, Chop, GADD34, p-PERK, p-eIF2α, and cleaved Caspase-12 at the protein levels. Moreover, ER stress was widely activated after treatment with ZnO NPs, while six of 84 marker genes significantly increased. ER stress response is a sensitive marker for checking the interruption of ER homeostasis by ZnO NPs. Furthermore, higher dosage of ZnO NPs (240 μM) quickly rendered ER stress response before inducing apoptosis. These results demonstrate that ZnO NPs activate ER stress-responsive pathway and the ER stress response might be used as an earlier and sensitive end point for nanotoxicological study. PMID:24490819

  9. Detection, attribution, and sensitivity of trends toward earlier streamflow in the Sierra Nevada

    USGS Publications Warehouse

    Maurer, E.P.; Stewart, I.T.; Bonfils, Celine; Duffy, P.B.; Cayan, D.

    2007-01-01

    Observed changes in the timing of snowmelt dominated streamflow in the western United States are often linked to anthropogenic or other external causes. We assess whether observed streamflow timing changes can be statistically attributed to external forcing, or whether they still lie within the bounds of natural (internal) variability for four large Sierra Nevada (CA) basins, at inflow points to major reservoirs. Streamflow timing is measured by "center timing" (CT), the day when half the annual flow has passed a given point. We use a physically based hydrology model driven by meteorological input from a global climate model to quantify the natural variability in CT trends. Estimated 50-year trends in CT due to natural climate variability often exceed estimated actual CT trends from 1950 to 1999. Thus, although observed trends in CT to date may be statistically significant, they cannot yet be statistically attributed to external influences on climate. We estimate that projected CT changes at the four major reservoir inflows will, with 90% confidence, exceed those from natural variability within 1-4 decades or 4-8 decades, depending on rates of future greenhouse gas emissions. To identify areas most likely to exhibit CT changes in response to rising temperatures, we calculate changes in CT under temperature increases from 1 to 5??. We find that areas with average winter temperatures between -2??C and -4??C are most likely to respond with significant CT shifts. Correspondingly, elevations from 2000 to 2800 in are most sensitive to temperature increases, with CT changes exceeding 45 days (earlier) relative to 1961-1990. Copyright 2007 by the American Geophysical Union.

  10. Non invasive blood flow measurement in cerebellum detects minimal hepatic encephalopathy earlier than psychometric tests

    PubMed Central

    Felipo, Vicente; Urios, Amparo; Giménez-Garzó, Carla; Cauli, Omar; Andrés-Costa, Maria-Jesús; González, Olga; Serra, Miguel A; Sánchez-González, Javier; Aliaga, Roberto; Giner-Durán, Remedios; Belloch, Vicente; Montoliu, Carmina

    2014-01-01

    CFF. BF in cerebellar hemisphere correlates with plasma cGMP and nitric oxide (NO) metabolites. BF in vermis cerebellar also correlates with NO metabolites and with 3-nitrotyrosine. IL-18 in plasma correlates with BF in thalamus and occipital lobe. CONCLUSION: Non invasive BF determination in cerebellum using ASL may detect MHE earlier than the PHES. Altered NO-cGMP pathway seems to be associated to altered BF in cerebellum. PMID:25206287

  11. What can we learn today from the Central European smog episode of 1985 (and earlier episodes)?

    PubMed

    Wichmann, H Erich

    2004-12-01

    In January 1985 an extended smog episode occurred in Central Europe. The Rhine-Ruhr area (Western Germany) was affected for 5 days with maximum concentrations of 0.8 mg/m3 SO2 and 0.6 mg/m3 TSP (24h averages). Health effects were investigated during the smog period and a control period before and after the smog. Daily mortality increased by 8%, hospital admissions (for respiratory and cardiovascular causes, RC) by 15%, outpatients (RC) by 12% and ambulance transports (RC) by 28%. Patients with chronic bronchitis from the Ruhr area cities showed more exacerbations during the episode, and in school children from the Netherlands lung function was reduced. In Augsburg (Southern Germany) the smog episode was less severe (maximum concentrations 0.2 mg/m3 SO2 and 0.1 mg/m3 TSP, 24 h averages). Here--by chance--the prospective MONICA study was ongoing. During the episode a significant increase of plasma viscosity, C-reactive protein and heart rate was observed in the participants. The highest ambient concentrations (maximum 24h average of 3.6 mg/m3 SO2) were measured in Erfurt (Eastern Germany). Surprisingly, no measurable increase of mortality occurred. This was explained by premature deaths during the period before the smog, were the concentrations had already been clearly above 1 mg/m3 SO2. An earlier episode took place in December 1962 in the Rhine-Ruhr area for 5 days with maximum concentrations of 5.0 mg/m3 SO2 and 2.4 mg/m3 TSP (24 h average). Daily mortality on average increased by 19%. In 1962 and 1985 the effects were stronger in cities with pollution mainly from traffic than in areas with pollution from industrial sources. In total, between 1962 and 1987 two major and several smaller smog episodes occurred in Central Europe. Patients with cardiovascular diseases were more severely affected than patients with respiratory diseases. Health effects were more strongly correlated with TSP than with SO2. PMID:15729831

  12. Per-protocol effect of earlier non-pneumatic anti-shock garment application for obstetric hemorrhage

    PubMed Central

    Ayadi, Alison El; Gibbons, Luz; Bergel, Eduardo; Butrick, Elizabeth; Huong, NT MY; Mkumba, Gricelia; Kaseba, Christine; Magwali, Thulani; Merialdi, Mario; Miller, Suellen

    2014-01-01

    Synopsis Earlier non-pneumatic anti-shock garment intervention was highly protective against maternal mortality and morbidity when analyzed to account for intervention fidelity; however, not all outcomes reached statistical significance. PMID:24721615

  13. Terrestrial environmental changes around the Gulf of Aden over the last 210 kyr deduced from the sediment n-alkane record: Implications for the dispersal of Homo sapiens

    NASA Astrophysics Data System (ADS)

    Isaji, Yuta; Kawahata, Hodaka; Ohkouchi, Naohiko; Murayama, Masafumi; Tamaki, Kensaku

    2015-03-01

    We analyzed long-chain (C25-C36) n-alkanes and pollen grains in sediments from the Gulf of Aden covering the last 212 kyr to reconstruct the surrounding terrestrial environment, a critical region for the dispersal of Homo sapiens. Substantial increases in the flux of n-alkanes during 200-185, 120-95, and 70-50 ka were interpreted to indicate enhanced vegetation biomass in the Arabian Peninsula and the northern part of the Horn of Africa or increase in lithogenic material inputs. Periods of enhanced n-alkane flux occurred during or immediately after pluvial episodes, indicating that the increased precipitation may have induced substantially enhanced vegetation biomass, creating favorable conditions for Homo sapiens. Additionally, vegetation may have increased due to moderate precipitation unrecorded by speleothems or in accordance with the lowering of sea level, indicating that the dispersal might have been possible even after the shift to an arid environment indicated by the speleothems.

  14. 200 kyrs of sediment deposition in the coastal lowlands of Bol'shoy Lyakhovsky - a record of deglaciation of the New Siberian Islands?

    NASA Astrophysics Data System (ADS)

    Schwamborn, Georg; Schirrmeister, Lutz; Wetterich, Sebastian; Fuchs, Margret; Meyer, Hanno; Siegert, Christine

    2016-04-01

    Bol'shoy Lyakhovsky, the southernmost island of the New Siberian Archipelago, holds the longest record of palaeoenvironmental history in the North Siberian Arctic. It stretches back to ~200 kyr before present. Next to palaeosols and floodplain deposits it includes prominent thermokarst deposits from the Last Interglacial and Yedoma (Ice Complex) sections from the Last Glacial. Yet, it is unknown, whether or not the depositional history of the area is affected by the deglaciation of the northern part of the New Siberian Archipelago. Potentially, it could give insights into the break-up of the proposed MIS 6 ice sheet located on the East Siberian Sea shelf. Polymodal particle size distributions in the sediment record suggest that more than one transport mechanism drove sediment accumulation from more than one source. From a cryo-sedimentological data set we focus on the mineral composition (63-125 μm fraction) to determine the provenance of the deposits and to identify possible changes of transport pathways. Complementary, we use pore ice hydrochemical data to track changes of the weathering solution preserved in permafrost. Presumably, the both complement each other, since the weathering products largely depend on the mineral composition. We conclude that the observed trends in the heavy mineral and pore ice chemical data of the frozen ground record reflect short-distance material transport from weathered bedrock to the depositional area. In this sense no portion of the 200 kyr record seems to be affected by the presumed MIS 6 ice sheet break-up, which at that time happened about 250 km north of the study site.

  15. Development of coccolithophore-based transfer functions in the western Mediterranean sea: a sea surface salinity reconstruction for the last 15.5 kyr

    NASA Astrophysics Data System (ADS)

    Ausín, B.; Hernández-Almeida, I.; Flores, J.-A.; Sierro, F.-J.; Grosjean, M.; Francés, G.; Alonso, B.

    2015-12-01

    A new data set of 88 marine surface sediment samples and related oceanic environmental variables (temperature, salinity, chlorophyll a, oxygen, etc.) was studied to quantify the relationship between assemblages of coccolithophore species and modern environmental conditions in the western Mediterranean Sea and the Atlantic Ocean, west of the Strait of Gibraltar. Multivariate statistical analyses revealed that coccolithophore species were primarily related to sea surface salinity (SSS), explaining an independent and significant proportion of variance in the coccolithophore data. A quantitative coccolithophore-based transfer function to estimate SSS was developed using the modern analog technique (MAT) and weighted-averaging partial least square regression (WA-PLS). The bootstrapped regression coefficient (R2boot) was 0.85MAT and 0.80WA-PLS, with a root-mean-square error of prediction (RMSEP) of 0.29MAT and 0.30WA-PLS (psu). The resulting transfer function was applied to fossil coccolithophore assemblages in the highly resolved (~ 65 years) sediment core CEUTA10PC08 from the Alboran Sea (western Mediterranean) in order to reconstruct SSS for the last 25 kyr. The reliability of the reconstruction was evaluated by assessing the degree of similarity between fossil and modern coccolithophore assemblages and by a comparison of reconstructions with fossil ordination scores. Analogs were poor for the stadials associated with Heinrich events 2 and 1 and part of the Last Glacial Maximum. Good analogs indicate a more reliable reconstruction of the SSS for the last 15.5 kyr. During this period, several millennial and centennial SSS changes were observed and associated with sea-level oscillations and variations in the Atlantic Water entering the Alboran.

  16. 78 FR 45114 - Revisions to the California State Implementation Plan, Antelope Valley Air Quality Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-26

    ... of these rules? We approved an earlier version of Rule 218 into the SIP on September 2, 2008 (73 FR... of Rule 431.1 into the SIP on October 19, 1984 (49 FR 41028).\\1\\ AVAQMD adopted revisions to Rule 431... Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993); does...

  17. 77 FR 66780 - Revisions to the California State Implementation Plan, South Coast Air Quality Management District

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-07

    ... earlier version of Rule 1113 into the SIP on August 17, 2011 (76 FR 50891). The SCAQMD adopted revisions... FR 51735, October 4, 1993); does not impose an information collection burden under the provisions of... Federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999); is not...

  18. 77 FR 2469 - Revisions to the California State Implementation Plan, Antelope Valley Air Quality Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-18

    ... (61 FR 56470). The AVAQMD adopted an earlier a revision to the SIP approved version of Rule 1134 on... monitoring period. (74 FR 63309) This determination suspended some of the planning requirements related to... Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990,'' 57 FR 13498 (April...

  19. Bilingual Children's Writing: Self-Correction and Revision of Written Narratives in Spanish and Nahuatl

    ERIC Educational Resources Information Center

    Francis, Norbert

    2005-01-01

    The article reports on findings from a replication of a study of bilingual children's editing and correction strategies. The earlier study analyzed revisions that 2nd, 4th, and 6th graders made to their own compositions, written in Spanish. The present study applied the same procedure and assessment rubric to the first draft of compositions…

  20. 78 FR 21542 - Revisions to the California State Implementation Plan, Santa Barbara County Air Pollution Control...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-11

    ... into the SIP on December 20, 2000 (65 FR 79752). We approved an earlier version of SCAQMD Rule 461 into the SIP on April 11, 2006 (71 FR 18216). The SCAQMD adopted revisions to the SIP-approved version on... review by the Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4,...

  1. A Revised FORTRAN IV Program for Three-mode Factor Analysis

    ERIC Educational Resources Information Center

    Walsh, James A.; Walsh, Roberta

    1976-01-01

    This Fortran IV revision of an earlier three-mode factor analysis program uses a main program-subprogram structure and core storage and is written in a sufficiently general form as to be easily convertable to most machines having a Fortran IV compiler. (RC)

  2. Standards for Foster Family Services Systems for Public Agencies. Revised Edition.

    ERIC Educational Resources Information Center

    Gross, Bruce; Winett, Sheila G.

    The standards presented here, a revision of the standards published in 1975, are intended to serve as uniform, national criteria by which public agencies can develop and assess the adequacy of their foster family services system. Major changes from the earlier standards include reduction of the number of standards, combination of the basic and…

  3. 75 FR 40726 - Revisions to the California State Implementation Plan, Sacramento Metropolitan Air Quality...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-14

    ... the SIP on May 4, 1999 (64 FR 23774). The SCAQMD adopted revisions to the SIP-approved version on... earlier version of SMAQMD Rule 456 was approved into the SIP on November 9, 1998 (63 FR 60214) and the... review by the Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4,...

  4. Evaluation of Revision Effect on Criterion Validity of Multiple-Component Measuring Instruments

    ERIC Educational Resources Information Center

    Raykov, Tenko

    2007-01-01

    A method for point and interval estimation of change in criterion validity of multiple-component measuring instruments as a result of revision is outlined. The procedure is developed within the framework of covariance structure modeling, which complements earlier methods for testing change in composite reliability due to addition or deletion of…

  5. 76 FR 40660 - Revisions to the California State Implementation Plan, San Joaquin Valley Air Pollution Control...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-11

    ... to Implement the 8-Hour Ozone National Ambient Air Quality Standard--Phase 2,'' 70 FR 71612 (November.... SUMMARY: EPA is proposing to approve revisions to the San Joaquin Valley Air Pollution Control District... an earlier version of Rule 4103 into the SIP on November 10, 2009 (74 FR 57907). The SJVUAPCD...

  6. 76 FR 7142 - Revisions to the California State Implementation Plan, Imperial County Air Pollution Control...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-09

    ...: EPA is proposing to approve revisions to the Imperial County Air Pollution Control District (ICAPCD... versions of these rules? We approved an earlier version of Rule 201 into the SIP on January 3, 2007 (72 FR... permit exemptions. Rule 103 was approved into the SIP on May 31, 1972 (37 FR 10842). The...

  7. 76 FR 37044 - Revisions to the California State Implementation Plan, San Joaquin Valley Unified Air Pollution...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-24

    ... Air Pollution Control District AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY: EPA is proposing to approve revisions to the San Joaquin Valley Unified Air Pollution Control...? We approved an earlier version of Rule 4354 into the SIP on August 17, 2006 (72 FR 41894)....

  8. 77 FR 35327 - Revisions to the California State Implementation Plan, San Joaquin Valley Unified Air Pollution...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-13

    ... Air Pollution Control District AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY: EPA is proposing to approve revisions to the San Joaquin Valley Unified Air Pollution Control... earlier version of Rule 4682 into the SIP on June 13, 1995 (60 FR 31086). The SJVUAPCD adopted...

  9. 75 FR 56889 - Revisions to the California State Implementation Plan, San Diego County Air Pollution Control...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-17

    ...: EPA is taking direct final action to approve revisions to the San Diego County Air Pollution Control... earlier version of Rule 2 into the SIP on February 3, 2000 (65 FR 5262). C. What is the purpose of the... Federalism (64 FR 43255, August 10, 1999) revokes and replaces Executive Orders 12612 (Federalism) and...

  10. Natural selection for earlier male arrival to breeding grounds through direct and indirect effects in a migratory songbird.

    PubMed

    Velmala, William; Helle, Samuli; Ahola, Markus P; Klaassen, Marcel; Lehikoinen, Esa; Rainio, Kalle; Sirkiä, Päivi M; Laaksonen, Toni

    2015-03-01

    For migratory birds, the earlier arrival of males to breeding grounds is often expected to have fitness benefits. However, the selection differential on male arrival time has rarely been decomposed into the direct effect of male arrival and potential indirect effects through female traits. We measured the directional selection differential on male arrival time in the pied flycatcher (Ficedula hypoleuca) using data from 6 years and annual number of fledglings as the fitness proxy. Using structural equation modeling, we were able to take into account the temporal structure of the breeding cycle and the hierarchy between the examined traits. We found directional selection differentials for earlier male arrival date and earlier female laying date, as well as strong selection differential for larger clutch size. These selection differentials were due to direct selection only as indirect selection for these traits was nonsignificant. When decomposing the direct selection for earlier male arrival into direct and indirect effects, we discovered that it was almost exclusively due to the direct effect of male arrival date on fitness and not due to its indirect effects via female traits. In other words, we showed for the first time that there is a direct effect of male arrival date on fitness while accounting for those effects that are mediated by effects of the social partner. Our study thus indicates that natural selection directly favored earlier male arrival in this flycatcher population. PMID:25859326

  11. Natural selection for earlier male arrival to breeding grounds through direct and indirect effects in a migratory songbird

    PubMed Central

    Velmala, William; Helle, Samuli; Ahola, Markus P; Klaassen, Marcel; Lehikoinen, Esa; Rainio, Kalle; Sirkiä, Päivi M; Laaksonen, Toni

    2015-01-01

    For migratory birds, the earlier arrival of males to breeding grounds is often expected to have fitness benefits. However, the selection differential on male arrival time has rarely been decomposed into the direct effect of male arrival and potential indirect effects through female traits. We measured the directional selection differential on male arrival time in the pied flycatcher (Ficedula hypoleuca) using data from 6 years and annual number of fledglings as the fitness proxy. Using structural equation modeling, we were able to take into account the temporal structure of the breeding cycle and the hierarchy between the examined traits. We found directional selection differentials for earlier male arrival date and earlier female laying date, as well as strong selection differential for larger clutch size. These selection differentials were due to direct selection only as indirect selection for these traits was nonsignificant. When decomposing the direct selection for earlier male arrival into direct and indirect effects, we discovered that it was almost exclusively due to the direct effect of male arrival date on fitness and not due to its indirect effects via female traits. In other words, we showed for the first time that there is a direct effect of male arrival date on fitness while accounting for those effects that are mediated by effects of the social partner. Our study thus indicates that natural selection directly favored earlier male arrival in this flycatcher population. PMID:25859326

  12. Controversies in Revision Rhinoplasty.

    PubMed

    Rosenberger, Eric S; Toriumi, Dean M

    2016-08-01

    Revision rhinoplasty is a complex operation with many variables that may influence the final esthetic and functional outcome of the procedure. Cartilage forms the structural framework of the lower two-thirds of nose and is essential for long-term support and maintenance of a patent nasal airway. The use of autologous cartilage grafting is the primary source of this material, limited by donor site quantity, quality, and harvest morbidity. Alloplastic materials, solid and injectable, are often used for augmentation purposes and may have devastating consequences. This article discusses past and current treatment concepts for various nasal deformities using available autologous grafting techniques. PMID:27400847

  13. Revision and Validation of the Revised Teacher Beliefs Survey.

    ERIC Educational Resources Information Center

    Benjamin, Jane

    This study revised the Teacher Beliefs Survey (S. Wooley and A. Wooley, 1999; TBS), an instrument to assess teachers beliefs related to constructivist and behaviorist theories of learning, and then studied the validity of the revised TBS. Drawing on a literature review, researchers added items for the existing constructs of the TBS and added a new…

  14. Online Discussion Processes: Effects of Earlier Messages' Evaluations, Knowledge Content, Social Cues and Personal Information on Later Messages

    ERIC Educational Resources Information Center

    Chen, Gaowei; Chiu, Ming Ming

    2008-01-01

    This study of the flow of online discussions examined how earlier messages affected later messages along five dimensions: (1) evaluations (agreement, disagreement, or unresponsive actions); (2) knowledge content (contribution, repetition, or null content); (3) social cues (positive, negative, or none); (4) personal information (number of visits);…

  15. Earlier Family Factors and Self-Silencing as Predictors of Depression in Late Adolescence: A Longitudinal Study.

    ERIC Educational Resources Information Center

    Fox, Barbara; And Others

    A construct labeled "self-silencing" or "loss of voice" as an aspect of female social development is emerging in current literature, and it is postulated that suppression of expression prescribes a more passive and muted role for women and lies at the root of depression in women. This study was a longitudinal project examining earlier parenting…

  16. Multimodal Revision Techniques in Webtexts

    ERIC Educational Resources Information Center

    Ball, Cheryl E.

    2014-01-01

    This article examines how an online scholarly journal, "Kairos: Rhetoric, Technology, Pedagogy," mentors authors to revise their webtexts (interactive, digital media scholarship) for publication. Using an editorial pedagogy in which multimodal and rhetorical genre theories are merged with revision techniques found in process-based…

  17. TRICARE reimbursement revisions. Final rule.

    PubMed

    2012-06-27

    This final rule provides several necessary revisions to the regulation in order for TRICARE to be consistent with Medicare. These revisions affect: Hospice periods of care; reimbursement of physician assistants and assistant-at-surgery claims; and diagnosis-related group values, removing references to specific numeric diagnosis-related group values and replacing them with their narrative description. PMID:22737760

  18. Gendered Performances during Peer Revision

    ERIC Educational Resources Information Center

    Styslinger, Mary E.

    2008-01-01

    This study explored the ways gender is accomplished in varied social contexts during the peer revision process in a secondary English classroom. Using a post-structural feminist theoretical framework, an analysis of classroom discourse provided a basis for understanding the performance of gender during peer revision, the effects of gender…

  19. Spatial and Temporal Variation in Primary Productivity (NDVI) of Coastal Alaskan Tundra: Decreased Vegetation Growth Following Earlier Snowmelt

    NASA Technical Reports Server (NTRS)

    Gamon, John A.; Huemmrich, K. Fred; Stone, Robert S.; Tweedie, Craig E.

    2015-01-01

    In the Arctic, earlier snowmelt and longer growing seasons due to warming have been hypothesized to increase vegetation productivity. Using the Normalized Difference Vegetation Index (NDVI) from both field and satellite measurements as an indicator of vegetation phenology and productivity, we monitored spatial and temporal patterns of vegetation growth for a coastal wet sedge tundra site near Barrow, Alaska over three growing seasons (2000-2002). Contrary to expectation, earlier snowmelt did not lead to increased productivity. Instead, productivity was associated primarily with precipitation and soil moisture, and secondarily with growing degree days, which, during this period, led to reduced growth in years with earlier snowmelt. Additional moisture effects on productivity and species distribution, operating over a longer time scale, were evident in spatial NDVI patterns associated with microtopography. Lower, wetter regions dominated by graminoids were more productive than higher, drier locations having a higher percentage of lichens and mosses, despite the earlier snowmelt at the more elevated sites. These results call into question the oft-stated hypothesis that earlier arctic growing seasons will lead to greater vegetation productivity. Rather, they agree with an emerging body of evidence from recent field studies indicating that early-season, local environmental conditions, notably moisture and temperature, are primary factors determining arctic vegetation productivity. For this coastal arctic site, early growing season conditions are strongly influenced by microtopography, hydrology, and regional sea ice dynamics, and may not be easily predicted from snowmelt date or seasonal average air temperatures alone. Our comparison of field to satellite NDVI also highlights the value of in-situ monitoring of actual vegetation responses using field optical sampling to obtain detailed information on surface conditions not possible from satellite observations alone.

  20. An early Pleistocene Mg/Ca-δ18O record from the Gulf of Mexico: Evaluating ice sheet size and pacing in the 40-kyr world

    NASA Astrophysics Data System (ADS)

    Shakun, J. D.; Raymo, M. E.; Lea, D. W.; Klinkhammer, G. P.

    2011-12-01

    Two decades ago, Joyce (1993) presented a planktonic δ18O record from ODP site 625 in the Gulf of Mexico and interpreted numerous light isotope excursions beginning at 2.5 Ma as reflecting Laurentide Ice Sheet meltwater pulses down the Mississippi River. This finding implied an extensive early Pleistocene (EP) ice sheet, seemingly at odds with the smaller global ice volume inferred from benthic δ18O at this time. The till record on land confirms that ice extended into the central U.S at least twice during the EP. We are developing a high-resolution paired Mg/Ca-δ18O record from site 625 to reconstruct sea surface temperatures and salinity over the EP and evaluate Joyce's meltwater interpretation. Initial results of our temperature-corrected δ18O record confirm his inference of large meltwater spikes at the onset of the Quaternary. Our approach could weigh in on several hypotheses concerning the size and pacing of Quaternary ice sheets. The Integrated Insolation hypothesis explains the puzzling lack of precession variability in marine δ18O during the 40-kyr world by arguing that ice sheets are sensitive to insolation integrated over the summer, which is largely controlled by obliquity. The Antiphase Hypothesis, on the other hand, suggests that EP precession variability was antiphased between northern and southern ice sheets, canceling out and leaving the in-phase obliquity component to dominate the marine δ18O record. This view implies that marine δ18O may underestimate Northern Hemisphere ice volume during the EP. The Regolith Hypothesis takes the small ice volume implied by marine δ18O at face value and, together with the large ice area suggested from Joyce's meltwater spikes and the mid-continent till record, argues that EP ice sheets had a flat-like-a-pancake geometry, which it attributes to fast ice flow over a deformable bed. Erosion of this bed in the mid-Pleistocene may then have led to larger, more sluggish ice sheets and the transition from 40 to

  1. New Archaeointensity Result from Middle-Eastern China and Its Constraints on the Variation of the Geomagnetic Field during the last 6 kyr

    NASA Astrophysics Data System (ADS)

    Cai, S.; Jin, G.; Deng, C.; Tauxe, L.; Qin, H.; Pan, Y.; Zhu, R.

    2015-12-01

    Archaeomagnetic study is an effective way to understand the variation of the geomagnetic field over periods of hundreds to thousands of years. We have carried out archaeointensity studies on archaeological artifacts, including pottery fragments, bricks and baked clay, collected from several sites covering the middle to eastern part of China spanning the past ~6 kyr. We designed detailed rock magnetic and archaeointensity experiments in this study. Rock magnetic results indicate that the main magnetic carriers of these samples are stable magnetite or titanomagnetite with mainly fine particles of SD and SP. About 40% of the specimens in the paleointensity experiment pass the strict selection criteria and are considered to record robust intensity values. The virtual axial dipole moments (VADMs) of our sites range from ~2.5×1022 to ~15.8×1022 Am2. We record three low intensity values with VADMs of less than 3×1022 Am2, two of them comparable to the one reported by Cai et al. (2015) at ~3000 BCE while the other one comparable to those reported by Cai et al. (2014) at ~2200 BCE, which supply further evidence for the existence of 'DIPs' (decreases in paleoinetnsity) in China during the period of ~3000-2000 BCE. A high intensity value of ~16×1022 Am2 is recorded by our new data at ~1300 BCE, which may represent a new spike at this time period. The low and high values recorded by our new data update the six-fold variation between ~2200 BCE and ~1300 BCE discussed in Cai et al. (2014) to eight-fold, which may indicate a stronger geodynamic process during this period. Our new data are generally in good agreement with the published data in China, Japan and Korea at similar time periods, except the extreme low and high values discussed above, which will improve the Eastern Asian model greatly. The new data together with the published data suggest severe fluctuation of the geomagnetic field in Eastern Asia during the last 6 kyr. Vast quantities of reliable data are needed to

  2. Changes in seasonality of organic matter supply to the sea floor in the Eastern Equatorial Pacific over the last 260 kyr based on benthic foraminiferal assemblages

    NASA Astrophysics Data System (ADS)

    Ovsepyan, Ekaterina; Ivanova, Elena; Vidal, Laurence

    2015-04-01

    At present, short- and long-term variations of sea-surface biological productivity in the Eastern Equatorial Pacific have been extensively studied in order to evaluate changes in efficiency of biological carbon dioxide pump in the past. Benthic foraminiferal assemblages are investigated from the IMAGES giant Core MD02-2529 (8°12.5' N, 84° 07.5'W, w.d. 1619 m) off Costa Rica recovered the last 262 kyr according to oxygen isotope stratigraphy confirmed by 15 AMS14C dates in the upper part of the core. A predominance of high productivity species (e.g. hispid Uvigerina, U. peregrina, M. barleeanus, B. mexicana, C. carinata, T. delicata, C. wuellerstorfi, P. bulloides, Chilostomella spp., Globobulimina spp.) in benthic foraminiferal assemblages indicates intensive organic matter supply to the sea floor throughout the interval studied. CABFAC factor analysis applied for the species percentages matrix reveals that changes in taxonomic composition are described by three factors. Factor 1 is loaded mainly to U. hispida and in a less degree to U. peregrina. According to the modern ecological notion (e.g. Loubere, Fariduddin, 1999), U. hispida is associated with high and fairly constant organic matter flux to the seabed. Hence, high values of factor 1 reflect high productivity and low seasonality conditions. Factor 2 is loaded positively to U. peregrina and negatively to U. hispida. U. peregrina prefers slightly degraded organic matter, whereas U. hispida is abundant within the regions where organic matter is fresh and dominated by diatoms. Thus, we suppose that maxima of factor 2 mirror high productivity conditions with non-regular flux of organic matter to the sea floor with several events of phytoplankton blooms over the year (moderate seasonality). We believe that fresh organic matter derived from the photic layer underwent bacterial decomposition between multiple flux pulses and thereby contributed to thrift U. peregrina assemblages. Factor 3 is loaded positively to M

  3. Hydrological and thermal changes along the last 2.7 kyr in the central-western Mediterranean based on a multi-archive approach: speleothem and marine sediments

    NASA Astrophysics Data System (ADS)

    Cisneros, Mercè; Cacho, Isabel; Fornós, Joan J.; Moreno, Ana; Stoll, Heather; Edwards, Larry; Cheng, Hai; Frigola, Jaime

    2016-04-01

    Climatic conditions over the last 2.7 kyr are reconstructed in base to six speleothems from a cave in Mallorca and a group of sediment cores from the Menorca Rise. Speleothem records provide a solid chronology in base to high resolution U/Th dating. Both δ 13C and particularly δ 18O records show pronounced oscillations related to pre-roman times as the Dark Middle Ages, the Medieval Climate Anomaly and the Little Ice Age. The geochemical proxies from the six studied speleothems have been stacked in a unique record, which provides decadal-multidecadal resolution. In parallel, Sea Surface Temperature (SST) conditions have been reconstructed in base to Globigerina bulloides-Mg/Ca ratios from a group of multicore records, and they have been combined with δ18O data to reconstruct changes in the evaporation-precipitation ratio of the basin. These records have also been stacked in a single anomaly curve after the accurate construction of robust multi-proxy chronologies (Cisneros et al., under evaluation). The comparison of the marine and speleothem records reveal the occurrence of synchronous changes in both SST and humidity conditions over land along the last 2.7 kyr, although the relationship of these two climatic variables changed along the different climatic events. These results support that the driest conditions occurred during part of the Roma Classic Period and also during the Medieval Climate Anomaly when climate conditions were mostly warm, but also during the second part of the Little Ice Age when cold conditions dominated. This combined land-sea proxy approach offers a powerful tool to reconstruct past climate variability with highly precise chronologies. REFERENCES: M. Cisneros, I. Cacho, J. Frigola, M. Canals, P. Masqué, B. Martrat, F. Lirer, and G. Margaritelli. Sea surface temperature variability in the central-western Mediterranean Sea during the last 2700 years: a multi-proxy and multi-record approach. Submitted on 28 Sep 2015 for open discussion on

  4. Oxygen isotopes of Pacific seawater, 0-40 kyr, based on d18O and Mg/Ca of benthic and planktic foraminifera: relation to deglacial sealevel rise.

    NASA Astrophysics Data System (ADS)

    Mix, A. C.; Klinkhammer, G. P.

    2007-12-01

    Combining high resolution (~200 year sample resolution) oxygen and carbon isotope measurements and Mg/Ca analyses in planktic (G. ruber and N. dutertrei) and benthic foraminifera (Uvigerina sp.; use of infaunal benthics minimizes likely CO3= effects) from the mid-depth eastern Pacific provides for detailed estimates of changing d18O of seawater over the past 40 kyr at ODP Site 1242. The key to this analysis is improved precision of the Mg/Ca analyses based on a new generation of high precision flow-through time-resolved analysis (FT-TRA) (e.g., average internal precision for Mg/Ca is now +/-0.005 benthic, and +/-0.015 planktic). This method is relatively insensitive to mild dissolution of heterogeneous shells, and thus requires no corrections for preservation. The change in seawater d18O (at 1364 m depth) between the Holocene and Last Glacial Maximum is 1.2 +/- 0.04 permil when averaged over the stages, consistent with pore-water diffusion estimates; however, millennial scale events (which the pore-water data cannot detect) bring the total range up to about 1.6 permil. Are such short-term events related to sealevel change, or do they reflect changing watermasses? Measurements of d13C data (C. wuellerstorfi), sensitive to modern subsurface watermass gradients, are not highly correlated to short- term changes in d18Oseawater suggesting a transient response to ice volume changes. Glacial weakening of AAIW (salty, high d18O, high d13C) relative to north Pacific watermasses (fresher, lower d18O, low d13C) suggest that the benthic d18Oseawater may underestimate total local changes related to ice volume (with a caveat regarding proper scaling of benthic Mg/Ca to temperature). Benthic d18Oseawater falls through the deglaciation in steps, starting at 18 cal ka, with maximum rates of change at 14-15 ka, and with secondary rapid steps at 16-17 ka and 10-11 kar. Planktic foraminifera yield smaller glacial-interglacial d18Oseawater values, with Holocene-to-LGM stage- average

  5. Erosional History of the Himalayan Range Since the Last 180 kyr: Clay Mineralogical and Geochemical Investigations From the Bay of Bengal

    NASA Astrophysics Data System (ADS)

    Joussain, R.; Liu, Z.; Christophe, C.

    2014-12-01

    Himalayan range and Indo-Gangetic plain are drained by one of the world's largest river system of the world: the Ganges-Brahmaputra Rivers. This river system is the first in term of sediment transport and thus constitute an interesting region to establish a relation between erosion and climate. Sediments from the Bay of Bengal indicate that the strength of summer monsoon rainfall is an important factor driving weathering and erosion of the Himalaya. Results of a high-resolution clay mineralogy study combined with major elements geochemistry and oxygen isotopes stratigraphy are reported for a deep-sea piston core collected 300 km off the Ganges-Brahmaputra Rivers estuary in the northern part of the Bay in Bengal. In this study, the top part (first 13.5 m) of Core MD12-3412 covers the last climatic cycle (last 180 kyr). This core reveals a monsoon-controlled chemical weathering and physical erosion history during the last 180 kyr in the Himalayan range and the Ganges-Brahmaputra Basin. Data show the contribution of Ganges-Brahmaputra Rivers, which drain the Himalayan range and the Indo-Gangetic plain. Clay mineral assemblages are dominated by illite and smectite, with lesser abundance of chlorite and kaolinite. Smectite/(illite + chlorite) and illite chemistry index are used as indices of chemical weathering rates. Thirty five new samples for ɛNd(0) analyses were selected (in turbidite and hemipelagic layers) during glacial and interglacial periods. Himalayan range is characterized by ɛNd(0) ≈ -16, whereas ɛNd(0) values along the Arakan coast are around -8. In this work we compared with ɛNd(0) values obtained previously on the free-carbonated fraction on Core MD77-180 which show that sediment from the eastern Bay of Bengal results from the mixing of material from the Himalayan and Indo-Burman ranges (with an average value of ɛNd(0) ≈ -13 for the last climatic cycle). These analyses give us information about the material coming from Ganges-Brahmaputra Rivers

  6. Effects of the Original Versus Revised Bloom's Taxonomy on Lesson Planning Skills: A Turkish Study Among Pre-Service Teachers

    NASA Astrophysics Data System (ADS)

    Bümen, Nilay T.

    2007-07-01

    The original taxonomy of educational objectives, developed by Benjamin S.␣Bloom and his associates in the 1950s, was revised several decades later by a group of educationists and cognitive psychologists, who developed a revised taxonomy (RT). This article describes a Turkish study carried out among a group of pre-service teachers in order to compare the influence of the two systems on lesson planning skills. The results confirmed other studies that have indicated a number of advantages of the revised system over the earlier one.

  7. An Earlier Start

    ERIC Educational Resources Information Center

    Jacobson, Linda

    2006-01-01

    Prekindergarten is becoming part of elementary school in the growing number of districts that treat the pre-K-3 years as a distinct learning period. Implementation of instructional connections is a primary goal behind a movement to make pre-K classrooms part of the regular life of elementary schools. Proponents of such efforts argue that children…

  8. A 100 Myr history of the carbon cycle based on the 400 kyr cycle in marine δ13C benthic records

    NASA Astrophysics Data System (ADS)

    Paillard, Didier; Donnadieu, Yannick

    2014-12-01

    Documenting the past coevolution of Earth temperatures and of the carbon cycle is of paramount importance for our understanding of climate dynamics. Atmospheric CO2 is well constrained over the last million years through direct measurements in air bubbles from Antarctic ice cores. For older times, many different and sometimes conflicting proxies have been suggested. Here we provide a new methodology to constrain the carbon cycle in the past, based on marine benthic δ13C records. Marine δ13C data are recording a persistent 400 kyr cycle, with an amplitude primarily linked to the total amount of carbon in the ocean, or dissolved inorganic carbon (DIC). By extracting this amplitude from published records, we obtain a new strong constraint on the 100 Myr history of Earth's carbon cycle. The obtained Cenozoic evolution of DIC is in surprisingly in a good agreement with existing reconstructions of pCO2, suggesting that pCO2 is mostly driven by DIC changes over this period. In contrast, we find no strong decreasing trend in DIC between the Cretaceous and the Cenozoic, suggesting that Cretaceous atmospheric pCO2 levels were limited, and high temperatures at this time should be explained by other mechanisms. Alternatively, high Cretaceous atmospheric pCO2 could occur as a consequence of changes in oceanic chemistry but not carbon content.

  9. Linkages between rapid climate variability and deep-sea benthic foraminifera in the deep Subantarctic South Atlantic during the last 95 kyr

    NASA Astrophysics Data System (ADS)

    Diz, Paula; Barker, Stephen

    2015-06-01

    We present a high-resolution record of benthic foraminifera fauna from a sediment core retrieved from the South Cape Basin (Subantarctic South Atlantic) spanning the last glacial cycle (95 kyr). Information provided by benthic foraminiferal assemblages together with paleoclimate proxies from the same core allow us to interpret changes in the style of primary production (episodic versus sustained) in relation to abrupt climate oscillations. Our results indicate that fluctuations in the abundance of the phytodetritus-related species, Epistominella exigua, are concomitant with millennial-scale high-latitude climate perturbations. Episodic phytoplankton blooms increased during a negative mode of the bipolar seesaw, irrespective of the magnitude of the perturbation (i.e., Heinrich stadial versus non-Heinrich stadial events). We provide a hypothesis linking the frequency and intensity of these events to atmospheric perturbations, interhemispheric climate variability, and millennial-scale changes in atmospheric CO2. A notable exception to the overall pattern is the generally high abundance of E. exigua across the globally synchronous onset of glacial marine oxygen isotope stage (MIS) 4, a period generally characterized by increased dustiness and low-quality organic carbon as inferred by the percentage of the nonphytodetritus species. This highlights the special characteristics governing the onset of MIS 4 in the Subantarctic.

  10. A high-resolution mid-Pleistocene temperature record from Arctic Lake El'gygytgyn: a 50 kyr super interglacial from MIS 33 to MIS 31?

    NASA Astrophysics Data System (ADS)

    de Wet, Gregory A.; Castañeda, Isla S.; DeConto, Robert M.; Brigham-Grette, Julie

    2016-02-01

    Previous periods of extreme warmth in Earth's history are of great interest in light of current and predicted anthropogenic warming. Numerous so called "super interglacial" intervals, with summer temperatures significantly warmer than today, have been identified in the 3.6 million year (Ma) sediment record from Lake El'gygytgyn, northeast Russia. To date, however, a high-resolution paleotemperature reconstruction from any of these super interglacials is lacking. Here we present a paleotemperature reconstruction based on branched glycerol dialkyl glycerol tetraethers (brGDGTs) from Marine Isotope Stages (MIS) 35 to MIS 29, including super interglacial MIS 31. To investigate this period in detail, samples were analyzed with an unprecedented average sample resolution of 500 yrs from MIS 33 to MIS 30. Our results suggest the entire period currently defined as MIS 33-31 (∼1114-1062 kyr BP) was characterized by generally warm and highly variable conditions at the lake, at times out of phase with Northern Hemisphere summer insolation, and that cold "glacial" conditions during MIS 32 lasted only a few thousand years. Close similarities are seen with coeval records from high southern latitudes, supporting the suggestion that the interval from MIS 33 to MIS 31 was an exceptionally long interglacial (Teitler et al., 2015). Based on brGDGT temperatures from Lake El'gygytgyn (this study and unpublished results), warming in the western Arctic during MIS 31 was matched only by MIS 11 during the Pleistocene.