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Sample records for cores record significant

  1. Ice cores record significant 1940s Antarctic warmth related to tropical climate variability.

    Science.gov (United States)

    Schneider, David P; Steig, Eric J

    2008-08-26

    Although the 20th Century warming of global climate is well known, climate change in the high-latitude Southern Hemisphere (SH), especially in the first half of the century, remains poorly documented. We present a composite of water stable isotope data from high-resolution ice cores from the West Antarctic Ice Sheet. This record, representative of West Antarctic surface temperature, shows extreme positive anomalies in the 1936-45 decade that are significant in the context of the background 20th Century warming trend. We interpret these anomalies--previously undocumented in the high-latitude SH--as indicative of strong teleconnections in part driven by the major 1939-42 El Niño. These anomalies are coherent with tropical sea-surface temperature, mean SH air temperature, and North Pacific sea-level pressure, underscoring the sensitivity of West Antarctica's climate, and potentially its ice sheet, to large-scale changes in the global climate.

  2. Climatological significance of an ice core net-accumulation record at Mt. Qomolangma (Everest)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An ice core record at Mt. Qomolangma (Everest) since 1954 reveals a sharp decline in net-accumulation in the 1960s, and the annual net-accumulation during the 1970s to the beginning of the 1990s is only half of that at the end of the 1950s. The decreased net-accumulation is coincident with glacier retreat, which is associated with recent temperature increase in the region that intensified the ablation. Under the background of global warming, such glacier variation trends will aggravate.

  3. Re—Examination on the Climatological Significance of the Ice Core δ18O Records from No.1 Glacier at the Head of Urumqi River

    Institute of Scientific and Technical Information of China (English)

    侯书贵

    2000-01-01

    Ice core δ18O recorde from the No.a glacier at the head of the Urumqi River were used o characterize the relationship between δ18O and contemporaneous surface air temperature(Ta) nearby the Daxigou Meteorological Station(3539 m above sea level,-2km away from the ice core drilling site),Although the ice core records of annually averaged δ18O are positively correlated with conemporaneous surface air temperature,especially summer air temperature,the correlation is less significant than that for the precipitation samples due to depositional and post-depositional modification processes,However,the Climatological significance of the ice corδ18O records can be still preserved to a certain degree,which moght extend the application of high altitude and sub-tropical ice core δ18O records to paleoclimate reconstruction.

  4. Climatic significance of δ18O records from an 80.36 m ice core in the East Rongbuk Glacier, Mount Qomolangma (Everest)

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Dongqi; QIN; Dahe; HOU; Shugui; KANG; Shichang; REN

    2005-01-01

    The δ18O variations in an 80.36 m ice core retrieved in the accumulation zone of the East Rongbuk Glacier, Mount Qomolangma (Everest), is not consistent with changes of air temperature from both southern and northern slopes of Himalayas, as well as these of the temperature anomalies over the Northern Hemisphere. The negative relationship between the δ18O and the net accumulation records of the ice core suggests the "amount effect" of summer precipitation on the δ18O values in the region. Therefore, the δ18O records of the East Rongbuk ice core should be a proxy of Indian Summer Monsoon intensity, which shows lower δ18O values during strong monsoon phases and higher values during weak phases.

  5. Alpine ice core records from Pacific North America

    Science.gov (United States)

    Steig, E. J.; Clark, D. H.; Pettit, E.

    2006-12-01

    Climate in the northeast Pacific shows significant multi-decadal and longer timescale variability, yet the instrumental record in western North America is relatively short. Paleoclimate proxy data, therefore, are essential to understanding climate variability in this region. A number of promising proxy-based reconstructions have been published recently, but additional constraints are needed. Ice core records are particularly useful for these reconstructions because they provide both high-resolution proxy data (such as δ18O and ion concentrations, which reflect large scale circulation changes) and direct measures of snow accumulation. Furthermore, at high altitude sites where ablation rates are small, snow accumulation is a highly reliable measure of total precipitation. At Mt. Logan, St. Elias Range, Yukon Territory, annual accumulation is significantly correlated with large scale climate indices such as the Aleutian Low pressure index. Perhaps more importantly, annual layer thickness in the Mt. Logan core is demonstrably reliable as an indicator of wintertime accumulation extremes not just at the site, but over a fairly large geographic area. Similar records have also been obtained at Mt. Churchill-Bona (AK) and Eclipse Dome (YT), also in the Wrangell/St. Elias range. A sufficiently complete spatial network of cores could in principle be used to develop a robust estimate of past winter precipitation variability across western Canada and Alaska. Mt. Waddington, British Columbia Coast Range, is one of the most promising sites for an ice core at temperate latitudes in North America. Mt. Waddington's location is highly complementary to the Wrangell/St. Elias sites: precipitation, temperature and geopotential height anomalies all tend to be opposite in sign in the two geographic regions. An accumulation record from Waddington, therefore, has considerable potential for refining reconstructions of precipitation and large scale circulation across the region. In July 2006

  6. Ice Core Records of Recent Northwest Greenland Climate

    Science.gov (United States)

    Osterberg, E. C.; Wong, G. J.; Ferris, D.; Lutz, E.; Howley, J. A.; Kelly, M. A.; Axford, Y.; Hawley, R. L.

    2014-12-01

    Meteorological station data from NW Greenland indicate a 3oC temperature rise since 1990, with most of the warming occurring in fall and winter. According to remote sensing data, the NW Greenland ice sheet (GIS) and coastal ice caps are responding with ice mass loss and margin retreat, but the cryosphere's response to previous climate variability is poorly constrained in this region. We are developing multi-proxy records (lake sediment cores, ice cores, glacial geologic data, glaciological models) of Holocene climate change and cryospheric response in NW Greenland to improve projections of future ice loss and sea level rise in a warming climate. As part of our efforts to develop a millennial-length ice core paleoclimate record from the Thule region, we collected and analyzed snow pit samples and short firn cores (up to 21 m) from the coastal region of the GIS (2Barrel site; 76.9317o N, 63.1467o W, 1685 m el.) and the summit of North Ice Cap (76.938o N, 67.671o W, 1273 m el.) in 2011, 2012 and 2014. The 2Barrel ice core record has statistically significant relationships with regional spring and fall Baffin Bay sea ice extent, summertime temperature, and annual precipitation. Here we evaluate relationships between the 2014 North Ice Cap firn core glaciochemical record and climate variability from regional instrumental stations and reanalysis datasets. We compare the coastal North Ice Cap record to more inland records from 2Barrel, Camp Century and NEEM to evaluate spatial and elevational gradients in recent NW Greenland climate change.

  7. An Antarctic ice core recording both supernovae and solar cycles

    CERN Document Server

    Motizuki, Yuko; Makishima, Kazuo; Bamba, Aya; Nakai, Yoichi; Yano, Yasushige; Igarashi, Makoto; Motoyama, Hideaki; Kamiyama, Kokichi; Suzuki, Keisuke; Imamura, Takashi

    2009-01-01

    Ice cores are known to be rich in information regarding past climates, and the possibility that they record astronomical phenomena has also been discussed. Rood et al. were the first to suggest, in 1979, that nitrate ion (NO3-) concentration spikes observed in the depth profile of a South Pole ice core might correlate with the known historical supernovae (SNe), Tycho (AD 1572), Kepler (AD 1604), and SN 1181 (AD 1181). Their findings, however, were not supported by subsequent examinations by different groups using different ice cores, and the results have remained controversial and confusing. Here we present a precision analysis of an ice core drilled in 2001 at Dome Fuji station in Antarctica. It revealed highly significant three NO3- spikes dating from the 10th to the 11th century. Two of them are coincident with SN 1006 (AD 1006) and the Crab Nebula SN (AD 1054), within the uncertainty of our absolute dating based on known volcanic signals. Moreover, by applying time-series analyses to the measured NO3- con...

  8. Early Holocene climate oscillations recorded in three Greenland ice cores

    DEFF Research Database (Denmark)

    Rasmussen, Sune Olander; Vinther, Bo Møllesøe; Clausen, Henrik Brink;

    2007-01-01

    A new ice core chronology for the Greenland DYE-3, GRIP, and NGRIP ice cores has been constructed, making it possible to compare the d18O and accumulation signals recorded in the three cores on an almost annual scale throughout the Holocene. We here introduce the new time scale and investigate d18O...... and accumulation anomalies that are common to the three cores in the Early Holocene (7.9–11.7 ka before present). Three time periods with significant and synchronous anomalies in the d18O and accumulation signals stand out: the well-known 8.2 ka event, an event of shorter duration but of almost similar amplitude...... around 9.3 ka before present, and the Preboreal Oscillation during the first centuries of the Holocene. For each of these sections, we present a d18O anomaly curve and a common accumulation signal that represents regional changes in the accumulation rate over the Greenland ice cap....

  9. Synchronization of ice core records via atmospheric gases

    Directory of Open Access Journals (Sweden)

    T. Blunier

    2007-06-01

    Full Text Available To interpret new high resolution climate records it becomes more and more important to know about the succession of climate events. Such knowledge is hard to get especially when dealing with different types of climate archives. Even for ice cores a direct synchronization between ice cores from Greenland and Antarctica has not been possible so far due to the lack of time markers occurring in both hemispheres. Fortunately, variations in the time series of global gas records can be used as indirect time markers. Here we discuss in detail the steps that are necessary to synchronize ice cores via global gas records exemplified on the synchronization of the EPICA ice core from Dronning Maud Land to a Greenland record from North GRIP.

  10. Events of abrupt change ofIndian monsoon recorded in Dasuopu ice core fromHimalayas

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Three ice cores distributed across Dasuopu glacier in Himalayas were recovered. A 400-year net annual accumulation record reconstructed from one of the cores reflects the major precipitation trend in the central Himalayas. This record is related closely to the Indian monsoon precipitation. Wavelet and moving T-test were applied to the 400-year-long Dasuopu accumulation record, and significant staggered variability and abrupt change of the record on interannual to centennial time scales are identified. Finally the possible reason for abrupt change of the accumulation record is discussed.

  11. A 780-year record of explosive volcanism from DT263 ice core in east Antarctica

    Institute of Scientific and Technical Information of China (English)

    ZHOU Liya; LI Yuansheng; Jihong Cole-da; TAN Dejun; SUN BO; REN Jiawen; WEI Lijia; WANG Henian

    2006-01-01

    Ice cores recovered from polar ice sheet Received and preserved sulfuric acid fallout from explosive volcanic eruptions. DT263 ice core was retrieved from an east Antarctic location. The ice core is dated using a combination of annual layer counting and volcanic time stratigraphic horizon as 780 years (1215-1996 A.D.). The ice core record demonstrates that during the period of approximately 1460-1800 A.D., the accumulation is sharply lower than the levels prior to and after this period. This period coincides with the most recent neoglacial climatic episode, the "Little Ice Age (LIA)", that has been found in numerous Northern Hemisphere proxy and historic records.The non-sea-salt SO2-4 concentrations indicate seventeen volcanic events in DT263 ice core. Compared with those from previous Antarctic ice cores, significant discrepancies are found between these records in relative volcanic flux of several well-known events. The discrepancies among these records may be explained by the differences in surface topography, accumulation rate, snow drift and distribution which highlight the potential impact of local glaciology on ice core volcanic records, analytical techniques used for sulfate measurement, etc. Volcanic eruptions in middle and high southern latitudes affect volcanic records in Antarctic snow more intensively than those in the Iow latitudes.

  12. Changing negative core beliefs with trial-based thought record

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    Thaís R. Delavechia

    2016-04-01

    Full Text Available Abstract Background Trial-based thought record (TBTR is a technique used in trial-based cognitive therapy (TBCT, and simulates a court trial. It was designed to restructure unhelpful core beliefs (CBs during psychotherapy. Objective To confirm previous findings on the efficacy of TBTR in decreasing patients’ adherence to self-critical and unhelpful CBs and corresponding emotions, as well as assessing the differential efficacy of the empty-chair approach relative to the static format of TBTR. Methods Thirty-nine outpatients were submitted to a 50-minute, one-session, application of the TBTR technique in the empty-chair (n = 18 or conventional (n = 21 formats. Patients’ adherence to unhelpful CBs and the intensity of corresponding emotions were assessed after each step of TBTR, and the results obtained in each format were compared. Results Significant reductions in percent values both in the credit given to CBs and in the intensity of corresponding emotions were observed at the end of the session (p < .001, relative to baseline values. ANCOVA also showed a significant difference in favor of the empty-chair format for both belief credit and emotion intensity (p = .04. Discussion TBTR may help patients reduce adherence to unhelpful CBs and corresponding emotions and the empty-chair format seems to be more efficacious than the conventional format.

  13. Significance of microvessel density in prostate cancer core biopsy

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    Salapura-Dugonjić Aleksandra

    2015-01-01

    Full Text Available Background/Aim. In prostate tumors, angiogenesis, measured as microvessel density, is associated with tumor stage and Gleason score. The aim of this study was determine neovascularization of prostatic adenocarcinomas in core biopsies and corresponding prostatectomies. Methods. The study population included 61 patients who underwent radical prostatectomy (RP for localized prostate carcinoma patients and did not receive chemohormonal, or radiation therapy before surgery. Tumor blocks were immunostained using the endothelial-specific antibody CD31 and subsequently evaluated at x 400 magnification in both biopsies and corresponding prostatectomies. Results. When comparing microvessel density in core biopsies and corresponding prostatectomies, no statistically significant difference was found (p > 0.1. A statistically significant positive correlation was found when determining correlation between microvessel density (as linear and categorical variable, i.e. with the cut-off value of 48 that was associated with the Gleason score (p 0.1. Conclusion. Microvessel density can be reliably applied to needle prostate biopsy specimens. Quantification of the microvascular density in biopsies is an accurate pre-operative predictor of tumor stage, discriminating between organconfined and organ-extending neoplasms.

  14. Linking two thousand years of European historical records with environmental change recorded in a high Alpine ice core

    Science.gov (United States)

    Bohleber, Pascal; Spaulding, Nicole; Mayewski, Paul; Kurbatov, Andrei; Hoffmann, Helene; Erhardt, Tobias; Fischer, Hubertus; More, Alexander; Loveluck, Christopher; Luongo, Matthew; Kabala, Jakub; McCormick, Michael

    2016-04-01

    Its extraordinary network of historical and archaeological records makes Europe exceptionally promising for investigating environmental change and human response over the last two thousand years. Among natural proxy archives, ice core records offer a wide range of environmental reconstructions including natural and human source histories of the chemistry of the atmosphere. To link these robust environmental records with historical evidence of past civilizations remains a great challenge, however. In central Europe the unique target for a comparison for environmental change recorded in ice cores and human activity is the small firn saddle of Colle Gnifetti (4550 m above sea level on the Italian-Swiss border). Its exceptionally low net accumulation make Colle Gnifetti (CG) the only feasible site in the Alps for retrieving a long-term ice core record beyond the last century. However, at CG rapid annual layer thinning eventually limits conventional cm-resolution analysis to multi-annual signals and hampers dating by annual layer counting beyond a few hundred years. Thereby, a crucial gap is introduced to the sub-seasonal time scale of events typically recorded in written archives. In our ongoing project we pioneer correlating the CG environmental ice core archive with a unique compilation of European historical records provided through the Harvard Initiative for the Science of the Human Past and the Digital Atlas of Roman and Medieval Civilization. For this purpose, state-of-the-art glacio-chemical analysis was performed on a newly recovered CG ice core, including continuous flow analysis chemistry and stable isotopes. A crucial contribution comes from the application of LA-ICP-MS (laser ablation ion coupled plasma mass spectrometry) to meter long sections of frozen ice samples, developed and operated by the University of Maine's Climate Change Institute, offering glacio-chemical records up to 100 μm in resolution. The new methods significantly improves sampling

  15. Biological proxies recorded in a Belukha ice core, Russian Altai

    Science.gov (United States)

    Papina, T.; Blyakharchuk, T.; Eichler, A.; Malygina, N.; Mitrofanova, E.; Schwikowski, M.

    2013-10-01

    Different biological proxies such as pollen, cysts, and diatoms were identified and quantified in the upper part of a Belukha ice core from the Russian Altai. The ice core from the Belukha glacier collected in 2001 (4062 m a.s.l., 49°48' N, 86°34' E) was analyzed with annual resolution in the period 1964-2000. Daily data of the frequency of synoptic patterns observed in the Northern Hemisphere along with daily data of precipitation have been used to identify the predominant atmospheric circulations (elementary circulating mechanisms, or ECMs) generating the entry of biological proxies on the glacier surface. It was shown that the high-resolution records of diatoms, cysts, spores, and plant pollen in the Belukha ice core are the biological proxies for the changes in the structure of precipitation in the Altai region since these records can reflect changes in the contribution of different atmospheric circulation to annual or seasonal precipitation. The joint consideration of the transport ability of the biological species and the data of precipitation allowed us to determine the main modern sources of biological proxies deposited at the Belukha glacier. The main sources of diatoms in the Belukha ice core are water bodies of the Aral, Caspian, and northern Kazakhstan basins; coniferous tree pollen originated from the taiga forest of the boreal zone of western Siberia; pollen of deciduous trees and herbs from steppe and forest-steppe vegetation in the northern Altai and eastern Kazakhstan; and cysts and spores of plants were transported from local water bodies and forests. The identified source regions of the biological species are supported by back trajectory analyses and are in good agreement with emission source regions of the trace elements in the ice core.

  16. First continuous phosphate record from Greenland ice cores

    Directory of Open Access Journals (Sweden)

    H. A. Kjær

    2011-11-01

    Full Text Available A continuous and highly sensitive absorption method for detection of soluble phosphate in ice cores has been developed using a molybdate reagent and a 2 m liquid waveguide (LWCC. The method is optimized to meet the low concentrations of phosphate in Greenland ice, it has a detection limit of around 0.1 ppb and a depth resolution of approximately 2 cm. The new method has been applied to obtain phosphate concentrations from segments of two Northern Greenland ice cores: from a shallow firn core covering the most recent 120 yr and from the recently obtained deep NEEM ice core in which sections from the late glacial period have been analysed. Phosphate concentrations in 20th century ice are around 0.32 ppb with no indication of anthropogenic influence in the most recent ice. In the glacial part of the NEEM ice core concentrations in the cold stadial periods are significantly higher, in the range of 6–24 ppb, while interstadial ice concentrations are around 2 ppb. In the shallow firn core, a strong correlation between concentrations of phosphate and insoluble dust suggests a similar deposition pattern for phosphate and dust. In the glacial ice, phosphate and dust also correlate quite strongly, however it is most likely that this correlation originates from the phosphate binding to dust during transport, with only a fraction coming directly from dust. Additionally a constant ratio between phosphate and potassium concentrations shows evidence of a possible biogenic land source.

  17. Microparticle record in the Guliya ice core and its comparison with polar records since the last interglacial

    Institute of Scientific and Technical Information of China (English)

    WU Guangjian; YAO Tandong; L.G. Thompson; LI Zhongqin

    2004-01-01

    Based on the study of oxygen isotope and microparticle in the Guliya ice core, atmospheric dust and environmental changes in the northwest Tibetan Plateau since the last interglacial were revealed. The microparticle record indicates that Iow dust load on the Plateau in the interglacial.Particle concentration increased rapidly when the climate turned into the last glacial and reached the maximum during the MIS 4. In the Last Glacial Maximum, however, the enhancement of microparticle concentration was slight, differing to those in the Antarctic and Greenland. On the orbital timescale, both the temperature on the Tibetan Plateau and summer solar insolation in the Northern Hemisphere had their impact on the microparticle record, but the difference in phase and amplitude also existed. Though having the same dust source, microparticle records in the ice cores on the Tibetan Plateau and the Greenland seem to have different significance.

  18. The clinical significance of lobular neoplasia on breast core biopsy.

    Science.gov (United States)

    Karabakhtsian, Rouzan G; Johnson, Ronald; Sumkin, Jules; Dabbs, David J

    2007-05-01

    A core biopsy diagnosis of atypical ductal epithelial hyperplasia is upstaged on follow-up excisional biopsy (FUEB) to in situ or invasive carcinoma in about 20% of cases, thus prompting a FUEB. In contrast, upstaging information for a core biopsy diagnosis of pure lobular neoplasia (LN), without mass lesions or other risk-associated lesions is less clear. In this retrospective study, we report the largest consecutive series of patients who had a breast core biopsy diagnosis of LN and a FUEB. Core needle breast biopsies with a diagnosis of LN were retrieved from our files for the period 1999 to 2005, yielding 110 patients. One hundred and one patients had a follow-up surgical excision. Cases of LN with coexisting high-risk lesions (n=9, 10%) were excluded from the study. Patients with associated mass lesions all had benign findings (n=15, 16%) and had no impact on the study results. The remaining 77 core biopsies had no masses or risk lesions and were mammographically Breast Imaging Reporting and Data System 4 (BIRADS) for microcalcifications. Overall, 8/77 (10%) of patients with a radiographic BIRADS 4 image with calcifications and a core biopsy diagnosis of LN on core biopsy were upstaged on FUEB to ductal carcinoma in situ or invasive carcinoma. The numbers upstaged from core biopsies were as follows: atypical lobular hyperplasia (ALH) 4/52 (8%), mixed ALH/lobular carcinoma in situ (LCIS) 1/9 (10%), and pure LCIS 3/16 (19%). A core biopsy of LCIS with neoplastic epithelial calcifications was nearly 3 times more likely to be upstaged on FUEB compared with ALH. We conclude that a finding of LN on breast core biopsy in a patient with a BIRADS 4 image and calcifications is associated with a risk of 8% to 19% of upstaging to a treatable disease on FUEB.

  19. Significance of Dental Records in Personal Identification in Forensic Sciences

    OpenAIRE

    Shanbhag, Vagish Kumar L.

    2016-01-01

    Forensic odontology is a branch that connects dentistry and the legal profession. One of the members in the forensic investigation team is a dentist. Dentists play an important and significant role in various aspects of the identification of persons in various forensic circumstances. However, several dentists and legal professionals are quite ignorant of this fascinating aspect of forensic odontology. A need was felt to fill this gap. The dental record is a legal document possessed by the den...

  20. The significance of trends in long-term correlated records

    CERN Document Server

    Tamazian, Araik; Bunde, Armin

    2014-01-01

    We study the distribution $P(x;\\alpha,L)$ of the relative trend $x$ in long-term correlated records of length $L$ that are characterized by a Hurst-exponent $\\alpha$ between 0.5 and 1.5 obtained by DFA2. The relative trend $x$ is the ratio between the strength of the trend $\\Delta$ in the record measured by linear regression, and the standard deviation $\\sigma$ around the regression line. We consider $L$ between 400 and 2200, which is the typical length scale of monthly local and annual reconstructed global climate records. Extending previous work by Lennartz and Bunde \\cite{Lennartz2011} we show explicitely that $P$ follows the student-t distribution $P\\propto [1+(x/a)^2/l]^{-(l+1)/2}$, where the scaling parameter $a$ depends on both $L$ and $\\alpha$, while the effective length $l$ depends, for $\\alpha$ below 1.15, only on the record length $L$. From $P$ we can derive an analytical expression for the trend significance $S(x;\\alpha, L)=\\int_{-x}^x P(x';\\alpha,L)dx'$ and the border lines of the $95\\%$ percent ...

  1. Detection of HCV core antigen and its diagnostic significance

    Directory of Open Access Journals (Sweden)

    YANG Jie

    2013-02-01

    Full Text Available ObjectiveTo compare the abilities of the hepatitis C virus (HCV core antigen (cAg test and the HCV RNA assay for confirming anti-HCV presence in order to determine the clinical utility of the HCV-cAg as an alternative or confirmatory diagnostic tool. MethodsSerum samples collected from 158 patients diagnosed with HCV infection were subjected to the enzyme-linked immunosorbent assay-based HCV-cAg test. The optical density (OD measured values were used to calculate the ratio of specimen absorbance to the cutoff value (S/CO. Simultaneously, the serum samples were subjected to PCR-based nucleic acid amplification quantitative fluorescence detection of HCV RNA. ResultsNone of the serum samples had a S/CO value <1 for the HCV-cAg test (100% negative, but all of the samples had a S/CO value >5 (100% positive. The HCV-cAg test sensitivity was 87.05%, specificity was 76.67%, positive predictive value was 9653%, and negative predictive value was 44.23%. As the S/CO value gradually increased, the significantly higher positive coincident rate of the HCV RNA test decreased. The HCV RNA negative coincident rate was significantly higher than that of the HCV-cAg test. HCV-cAg S/CO values between 1 and 2 corresponded to an HCV RNA values between 1.0×103 copies/ml and 1.0×104 copies/ml. The highest S/CO value obtained was 1.992. ConclusionThe HCV-cAg test is comparable to the HCV RNA assay for diagnosing HCV infection.

  2. A PRIMARY RECOGNITION ON THE CLIMATIC SIGNIFICANCE OF ICE CORE ISOTOPE RECORD IN NAIMONA'NYI OF WEST TIBETAN PLATEAU%青藏高原西部纳木那尼冰芯同位素记录的气候意义初探

    Institute of Scientific and Technical Information of China (English)

    田立德; 姚檀栋; 文蓉; 翁永标; 赵中平; 曲冬梅

    2012-01-01

    Naimona'nyi Peak,with altitude of 7694m,is one of the highest peaks in West Himalayas. Glaciers flow from the center of the peak to each side. Naimona'nyi glacier is one of the largest glaciers in West Himalayas, and also the potential glacier for deep ice core study. This glacier locates in the boundary area between the westerly atmospheric circulation system and Indian monsoon system,and different moisture supplies bring precipitation with different isotopic signals. It is thus important to validate the climate significance of the isotope record from Naimona'nyi ice cores. An 8. 78-meter shallow ice core drilled in 2008 on this glacier threw light on the explanation of the isotopic record. This ice core(30°26. 5'N,81°19. 5'E;6100m a. S. 1. ) was drilled in the accumulation area of the glacier,and it was dated back to 2001 by the clear seasonality of δ18O record. Results shows the annual δ18O variation matches pretty well with the local annual air temperature at Burang(30°17'N,81°15'N;3900m a. S. 1. ) , with a square coefficient of 0. 4. From the spatial variation,there is an abrupt shift of the ice core δ18O record from the temperature-dependant in the northern plateau to the precipitation-dependent in the southern plateau. The result from this Naimona'nyi shallow ice core indicates that the δ18O in the Naimona'nyi ice core reflect temperature change, and implies that the Naimona'nyi glacier precipitation is less impacted by the summer monsoon impact. This can also be supported by the seasonal precipitation patterns at the Burang meteorological station, where the monsoon signal is only limited in the July and August precipitation. The annual accumulation rate from this ice core is 775mm water equivalent during 2001 ~ 2008,about S times of annual precipitation at the Burang meteorological station, showing the higher precipitation zone in glacier region and probably implying different moisture sources at high elevation. The result also demonstrates that the

  3. Denali Ice Core Record of North Pacific Hydroclimate, Temperature and Atmospheric Circulation over the Past Millennium

    Science.gov (United States)

    Osterberg, E. C.; Wake, C. P.; Kreutz, K. J.; Winski, D.; Ferris, D. G.; Introne, D.; Campbell, S.; Birkel, S. D.

    2015-12-01

    While tree ring and lake sediment core studies have revealed a great deal about North Pacific (e.g. Alaska) surface temperature variability over the past millennium, we do not have an equivalent understanding of North Pacific hydroclimate variability or temperatures at high elevations. A millennial-length precipitation proxy record is needed to place late 20th century Alaskan precipitation increases into longer context, and to evaluate hydroclimate changes during the Little Ice Age and Medieval Climate Anomaly. High-elevation summer temperature records would be valuable for understanding the sensitivity of Alaskan glaciers to past warm and cool periods. Here we present an overview of the new Denali Ice Core record collected from the summit plateau (4000 m a.s.l.) of Mt. Hunter (63° N, 151° W) in Denali National Park, Alaska. Two parallel ice cores were collected to bedrock (208 m in length) in May-June 2013, sampled using the Dartmouth continuous melter system, and analyzed for major ions, trace elements, particle concentration and size distribution, and stable isotope ratios at Dartmouth and the Universities of Maine and New Hampshire. The cores are dated using robust annual oscillations in dust elements, methanesulfonate, ammonium, and stable isotopes, and validated using major volcanic eruptions recorded as sulfate, chloride and heavy metal spikes, and the 1963 nuclear weapons testing 137Cs spike. Preliminary analyses indicate a significant increase in both summer temperature and annual accumulation over the 20th century, and significant relationships with major ocean-atmospheric modes including the Pacific Decadal Oscillation. We compare the new Denali record to the Eclipse Icefield and Mt. Logan ice core records and develop composite records of North Pacific hydroclimate and atmospheric circulation variability over the past millennium.

  4. Boreal fire records in Northern Hemisphere ice cores: a review

    Science.gov (United States)

    Legrand, Michel; McConnell, Joseph; Fischer, Hubertus; Wolff, Eric W.; Preunkert, Susanne; Arienzo, Monica; Chellman, Nathan; Leuenberger, Daiana; Maselli, Olivia; Place, Philip; Sigl, Michael; Schüpbach, Simon; Flannigan, Mike

    2016-10-01

    Here, we review different attempts made since the early 1990s to reconstruct past forest fire activity using chemical signals recorded in ice cores extracted from the Greenland ice sheet and a few mid-northern latitude, high-elevation glaciers. We first examined the quality of various inorganic (ammonium, nitrate, potassium) and organic (black carbon, various organic carbon compounds including levoglucosan and numerous carboxylic acids) species proposed as fire proxies in ice, particularly in Greenland. We discuss limitations in their use during recent vs. pre-industrial times, atmospheric lifetimes, and the relative importance of other non-biomass-burning sources. Different high-resolution records from several Greenland drill sites and covering various timescales, including the last century and Holocene, are discussed. We explore the extent to which atmospheric transport can modulate the record of boreal fires from Canada as recorded in Greenland ice. Ammonium, organic fractions (black and organic carbon), and specific organic compounds such as formate and vanillic acid are found to be good proxies for tracing past boreal fires in Greenland ice. We show that use of other species - potassium, nitrate, and carboxylates (except formate) - is complicated by either post-depositional effects or existence of large non-biomass-burning sources. The quality of levoglucosan with respect to other proxies is not addressed here because of a lack of high-resolution profiles for this species, preventing a fair comparison. Several Greenland ice records of ammonium consistently indicate changing fire activity in Canada in response to past climatic conditions that occurred during the last millennium and since the last large climatic transition. Based on this review, we make recommendations for further study to increase reliability of the reconstructed history of forest fires occurring in a given region.

  5. Comparison of northern and central Greenland ice cores records of methanesulfonate covering the last glacial period

    DEFF Research Database (Denmark)

    Jonsell, U.; Hansson, M. E.; Siggaard-Andersen, M-L-

    2007-01-01

    Methanesulfonate (MS-) is measured in ice cores with the objective to obtain a proxy record of marine phytoplankton production of dimethylsulfide (DMS). We present a continuous MS- record covering the last glacial period from the North Greenland Ice Core Project (NGRIP) ice core and compare...... this record with the corresponding records previously presented from Greenland and, in particular, with the GISP2 ice core located 320 km south of NGRIP. Despite that the records have similar mean concentrations, their responses to climatic changes during the last glacial period are slightly different. NGRIP...... ice cores. Udgivelsesdato: 31 July...

  6. Clinical significance of SNAP somnography test acoustic recording.

    Science.gov (United States)

    Galer, Chad; Yonkers, Anthony; Duff, Wallace; Heywood, Barbara

    2007-02-01

    To examine the clinical significance of acoustic data recorded by the SNAP home polysomnography system (SNAP Laboratories, Glenview, IL). Retrospective analysis of SNAP data from 59 patients undergoing evaluation for sleep apnea at the University of Nebraska Medical Center and an associated private practice in Omaha, NE. Snoring did not correlate with anthropometric variables such as body mass index and neck circumference. Statistical analysis showed no correlation between respiratory disturbance index and the maximum or average loudness of snoring. Average loudness was predictive of the presence of sleep apnea. Spectral analysis of snoring sonography found that the proportion of snoring events associated with a palatal source correlated strongly with the loudness of snoring. These data suggest that analysis of snoring has limited utility in the evaluation of the patient with sleep apnea but may be able to select patients who would benefit from palatal procedures to reduce snoring.

  7. The 1500m South Pole Ice Core: Recovering a 40 Ka Environmental Record

    Science.gov (United States)

    Casey, Kimberly Ann; Neumann, Thomas Allen; Fudge, T. J.; Neumann, T. A.; Steig, E. J.; Cavitte, M. G. P.; Blankenship, D. D.

    2014-01-01

    Supported by the US National Science Foundation, a new 1500 m, approximately 40 ka old ice core will be recovered from South Pole during the 2014/15 and 2015/16 austral summer seasons using the new US Intermediate Depth Drill. The combination of low temperatures, relatively high accumulation rates and low impurity concentrations at South Pole will yield detailed records of ice chemistry and trace atmospheric gases. The South Pole ice core will provide a climate history record of a unique area of the East Antarctic plateau that is partly influenced by weather systems that cross the West Antarctic ice sheet. The ice at South Pole flows at approximately 10m a(exp-1) and the South Pole ice-core site is a significant distance from an ice divide. Therefore, ice recovered at depth originated progressively farther upstream of the coring site. New ground-penetrating radar collected over the drill site location shows no anthropogenic influence over the past approximately 50 years or upper 15 m. Depth-age scale modeling results show consistent and plausible annual-layer thicknesses and accumulation rate histories, indicating that no significant stratigraphic disturbances exist in the upper 1500m near the ice-core drill site.

  8. Methane and nitrous oxide in the ice core record.

    Science.gov (United States)

    Wolff, Eric; Spahni, Renato

    2007-07-15

    Polar ice cores contain, in trapped air bubbles, an archive of the concentrations of stable atmospheric gases. Of the major non-CO2 greenhouse gases, methane is measured quite routinely, while nitrous oxide is more challenging, with some artefacts occurring in the ice and so far limited interpretation. In the recent past, the ice cores provide the only direct measure of the changes that have occurred during the industrial period; they show that the current concentration of methane in the atmosphere is far outside the range experienced in the last 650,000 years; nitrous oxide is also elevated above its natural levels. There is controversy about whether changes in the pre-industrial Holocene are natural or anthropogenic in origin. Changes in wetland emissions are generally cited as the main cause of the large glacial-interglacial change in methane. However, changing sinks must also be considered, and the impact of possible newly described sources evaluated. Recent isotopic data appear to finally rule out any major impact of clathrate releases on methane at these time-scales. Any explanation must take into account that, at the rapid Dansgaard-Oeschger warmings of the last glacial period, methane rose by around half its glacial-interglacial range in only a few decades. The recent EPICA Dome C (Antarctica) record shows that methane tracked climate over the last 650,000 years, with lower methane concentrations in glacials than interglacials, and lower concentrations in cooler interglacials than in warmer ones. Nitrous oxide also shows Dansgaard-Oeschger and glacial-interglacial periodicity, but the pattern is less clear.

  9. Dust records from three ice cores: relationships to spring atmospheric circulation over the Northern Hemisphere

    Science.gov (United States)

    Kang, Shichang; Mayewski, Paul A.; Yan, Yuping; Qin, Dahe; Yao, Tandong; Ren, Jiawen

    Non-sea-salt Mg 2+ (nssMg 2+) records from three Northern Hemisphere ice cores (Mt. Everest, Himalayas; Mt. Logan, Yukon Territory; and 20D, southern Greenland) are presented as a proxy of atmospheric dust. NssMg 2+ concentrations of both Mt. Everest and 20D ice core have increased since the 20th century. Relationships between the three ice core annual nssMg 2+ series and instrumental sea-level pressure (SLP) series of spring (March-April-May) are investigated for the last century (AD 1899-1996), in order to develop an understanding of dust aerosol transport over the Northern Hemisphere during the spring season. On a hemispheric scale, an enhanced spring Arctic High weakens dust aerosol transport from central Asia to subarctic regions (e.g., southern Greenland and Yukon Territory), but strengthens transport of dust to the Himalaya (e.g., Mt. Everest). An intensification of the Siberian High may strengthen transport of dust aerosols to Greenland, and an enhancement of the Tibetan High strengthens transport to Himalaya and Yukon regions in spring. A stronger spring Azores High favors dust transport to both the Himalayas and south Greenland. On a regional scale, a deepened spring Icelandic Low and Aleutian Low increases transport of dust aerosols to Greenland and the Yukon Territory, respectively. Understanding these transport patterns is significant for the interpretation of ice core records and reconstruction of atmospheric circulation using longer records.

  10. Seasonal variations of dust record in the Muztagata ice cores

    Institute of Scientific and Technical Information of China (English)

    WU GuangJian; YAO TanDong; XU BaiQing; TIAN LiDe; LI Zhen; DUAN KeQin

    2008-01-01

    Based on the oxygen isotope ratio and microparticle record in ice cores recovered at Mt.Muztagata,Eastern Pamirs,the seasonal variations of atmospheric dust have been reconstructed for the past four decades.High dust concentrations and coarser particle grains have the similar trend with oxygen iso-tope value.Our statistical results indicate that 50%--60% high dust concentration samples occur dur-ing the season with high oxygen isotope values (summer),while low dust storm frequency during spring and winter.Back-trajectory analysis shows that the air mass hitting Muztagata predominately came from West Asia (such as Iran-Afghanistan Plateau) and Central Asia,which are the main dust source area for Muztagata.Dust storms in those source areas most frequently occur during summer (from May to August),while frequent dust storm events in northern China mainly occur during spring (March to May).Regions in the path of Asian dust transport,such as in Japan,the North Pacific,and Greenland,also show high dust concentrations during spring (from March to May).Our results indicate that dust storms have different seasonality in different regions within Asia.

  11. A Significant Population Signal in Iranian Temperature Records

    Directory of Open Access Journals (Sweden)

    Shouraseni Sen Roy

    2016-01-01

    Full Text Available We assembled daily maximum and minimum temperature records for 31 stations throughout Iran over the period 1961–2010. As with many other areas of the world, we found that both the maximum and minimum temperatures were increasing overall with the minimum temperatures increasing twice as fast as the maximum temperatures. We gathered population data for the stations near the beginning and end of the temperature records and found in all seasons and for both the maximum and minimum temperatures the magnitude of population growth positively influenced the temperature trends. However, unlike so many other studies, we found the strongest population growth signal in the winter for the maximum temperatures. We found evidence that this winter-season population-temperature signal is related snow cover. Our results illustrate that any number of processes are involved in explaining trends in historical maximum and minimum temperature records.

  12. Dasuopu ice core record of atmospheric methane over the past 2000 years

    Institute of Scientific and Technical Information of China (English)

    XU; Baiqing

    2001-01-01

    [1]Barnola, J. M., Raynaud, D., Korotkevich, Y. S. et al., Vostok ice core provides 160,000-year record of atmospheric CO2, Nature, 1987, 329: 408.[2]Chappellaz, J., Barnola, J. M., Raynaud, D. et al., Ice core record of atmospheric methane over the past 160 000 years, Nature, 1990, 345: 127.[3]Raynaud, D., Jouzel, J., Barnola, J. M. et al., The ice record of greenhouse gases, Science, 1993, 259: 926.[4]Blake, D. R., Rowland, F. S., Continuing worldwide increase in tropospheric methane, 1978 to 1987, Science, 1988, 239: 1129.[5]Steele, L. P., Dlugokencky, E. J., Lang, P. M. et al., Slowing down of the global accumulation of atmospheric methane during the 1980s, Nature, 1992, 358: 313.[6]Dlugokencky, E. J., Steele, L. P., Lang, P. M. et al., The growth rate and distribution of atmospheric methane, J. Geophys. Res., 1994, 99: 17021.[7]Lowe, D. C., Brenninkmeijer, C. A. M., Brailsford, G. W. et al., Concentration and 13C records of atmospheric methane in New Zealand and Antarctica: evidence for changes in methane sources, J. Geophys. Res., 1994, 99: 16913.[8]Rasmusen, R. A., Khalil, M. A. K., Atmospheric methane in the recent and ancient atmosphere: concentrations, trends and interhemispheric gradient, J. Geophys. Res., 1984, 89(D7): 11599.[9]Blunier, T., Chappellaz, J., Schwander, J. et al., Atmospheric methane record from a Greenland ice core over the last 1000 years, Geoph. Res. Lett., 1993, 20(20): 2219.[10]Yao Tandong, One of the ten science and technology achievements 1997 in China: The recover of ice cores at the eleva-tion of 7000 m in Qinghai-Tibetan plateau and its significance, J. Glaciology & Geocryology (in Chinese), 1998, 20(1): 1.[11]Yao Tandong, Pu Jiancheng, Wang Ninglian et al., The discovery of a new densification in China, Chinese Science Bulle-tin (in Chinese), 1998, 43: 94.[12]Xu Baiqing, Yao Tandong, A study on the air bubble formation process at the elevation of 7100 m in Dasuopu glacier, J

  13. The Colorado Plateau Coring Project: A Continuous Cored Non-Marine Record of Early Mesozoic Environmental and Biotic Change

    Science.gov (United States)

    Irmis, Randall; Olsen, Paul; Geissman, John; Gehrels, George; Kent, Dennis; Mundil, Roland; Rasmussen, Cornelia; Giesler, Dominique; Schaller, Morgan; Kürschner, Wolfram; Parker, William; Buhedma, Hesham

    2017-04-01

    approximation of their host rock's depositional age, along with significant populations of early Paleozoic and Proterozoic zircons which will be used to identify provenance. Thermal demagnetization of paleomagnetic samples show that most Moenkopi and some fine-grained Chinle lithologies preserve a primary magnetization, and thus will allow the construction of a robust magnetostratigraphy for portions of the Triassic section. Soil carbonates are abundant throughout the cored section. All data will be integrated to construct an exportable chronostratigraphic framework that will allow us to test a number of major questions with global implications for understanding the early Mesozoic world, including: 1) do independent U-Pb ages support the accuracy of the Newark astronomically-calibrated geomagnetic polarity timescale? 2) is the mid-Late Triassic biotic turnover observable in the western US coincident with the Manicouagan bolide impact? and 3) are cyclical climate variations apparent in the cored record, and do they reflect variations in atmospheric CO2?

  14. Temperature and methane records over the last 2 ka in Dasuopu ice core

    Institute of Scientific and Technical Information of China (English)

    PU; Jianchen; (

    2002-01-01

    : The recover of ice cores at the elevation of 7000 m in Qinghai-Tibetan plateau and its significance, J. Glaciology & Geocryology (in Chinese), 1998, 20(1): 1-2.[15]Yao Tandong, Pu Jianchen, Wang Ninglian et al., A new type of ice formation zone found in the Himalayas, Chinese Science Bulletin, 1999, 44(5): 469-473.[16]Xu Baiqing, Yao Tandong, A study on the air bubble formation process at the elevation of 7100 m in Dasuopu glacier, J. Glaciology & Geocryology (in Chinese), 1999, 21(2): 115-120.[17]Yao, T. D., Duan, K. Q., Tian, L. D., Glacial accumulation record in the Dasuopu ice core and Indian summer monsoon rainfall in the past 400 years, Science in China (in Chinese), Ser. D, 2000, 30(6): 619-627.[18]Thompson, L. G., Yao, T., Mosley-Thompson, E. et al., A High-resolution Millennial Record of the South Asian Monsoon from Himalayan Ice Cores, Science, 2000, 289(5486): 1916-1920.[19]Huang Cuilan, Yao Tandong, Pu Jianchen et al., Environmental information recorded in shallow ice core of Dasuopu glacier in the Qinghai-Tibetan Plateau, Chinese Science Bulletin, 1998, 43(22): 1935-1936.[20]Duan Keqin, Wang Ninglian, Li Yuefang, Accumulation in Dasuopu ice core in Qinghai-Tibet Plateau and solar activity, Chinese Science Bulletin, 2000, 45(11): 1038-1041.[21]Duan, K.Q., Yao, T. D., Modern environment and climate recorded in the Dasuopu ice core, in Formation and Evolution, Environmental Changes and Sustainable Development on the Tibetan Plateau (ed. Zheng Du et al), Beijing: Academic Press, 54-61.[22]Huo Wenmian, Yao Tandong, Li Yuefang, Inceasing atmospheric pollution revealed by Pb record of a 7000-m ice core, Chinese Science Bulletin, 1999, 44(14): 1309-1312.[23]Raynaud, D., Chappellaz, J., The record of atmospheric methane, in Atmospheric Methane: Sources, Sinks, and Role in the Global Change, NATO ASI Series (ed. Khalil, M. A. K.), Berlin, Heidelberg: Springer-Verlag, 1993, 113: 38-59.[24]Wang Mingxing, Atmospheric Chemistry

  15. Significance of Two New Pleistocene Plant Records from Western Europe

    Science.gov (United States)

    Field, Michael H.; Velichkevich, Felix Y.; Andrieu-Ponel, Valerie; Woltz, Phillipe

    2000-09-01

    The first records of extinct Caulinia goretskyi (Dorofeev) Dorofeev (synonym Najas goretskyi Dorofeev) in western Europe and of Potamogeton occidentalis M.H. Field sp. nov. were obtained from plant macrofossil analyses of Middle Pleistocene temperate stage deposits exposed at Trez Rouz, Brittany, France. Palynological assemblages recovered suggest correlation with the Holsteinian Stage. This discovery greatly expands the western limit of the paleogeographical distribution of Caulinia goretskyi. The record of Potamogeton occidentalis indicates an affinity with the eastern Asiatic flora, as the fruits resemble those of the extant Potamogeton maackianus A. Bennett. Other extinct Pleistocene species related to P. maackianus have been described, and it is possible to follow the development of this group through the Pleistocene in the European fossil record. These new finds illustrate the importance of a complete paleobotanical approach (both plant macrofossil and palynological analyses). The plant macrofossil assemblages not only provide detailed insight into local vegetation and environment, because they are often not transported long distances (in temperate areas) and can frequently be identified to species level; they can also offer the opportunity to investigate Pleistocene evolutionary trends.

  16. Deconvolution-based resolution enhancement of chemical ice core records obtained by continuous flow analysis

    DEFF Research Database (Denmark)

    Rasmussen, Sune Olander; Andersen, Katrine K.; Johnsen, Sigfus Johann;

    2005-01-01

    Continuous flow analysis (CFA) has become a popular measuring technique for obtaining high-resolution chemical ice core records due to an attractive combination of measuring speed and resolution. However, when analyzing the deeper sections of ice cores or cores from low-accumulation areas, there ...

  17. Temperature and methane records over the last 2 ka in Dasuopu ice core

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    High resolution δ18O and methane records over the last 2ka have been reconstructed from Dasuopu ice core recovered from the Himalayas. Analysis shows that the δ18O record correlates well with the Northern Hemispheric temperature, Dunde ice core record, and with temperature record in eastern China. The warming trend detected in δ18O record from the last century is similar to that during the Medieval warm period. There is a dramatic increasing in methane concentration in the Dasuopu ice core, which reached 1031 nmol@mol-1 in 1997. Moreover, methane concentration in the Dasuopu ice core is about 15%-20% higher than that in Antarctica and Greenland. There is a positive correlation between methane concentration and δ18O in Dasuopu ice core.

  18. Tropical Ice Core Records: Evidence for Asynchronous Glaciation on Milankovitch Time Scales

    Science.gov (United States)

    Thompson, L. G.

    2001-12-01

    Ice core records are available from selected high altitude, low and mid-latitude ice caps. Comparisons are made among the histories from the Tibetan Plateau, the tropical Andes of South America, and Kilimanjaro in East Africa. Three of these records (Guliya in China, Huascarán in Peru, and Sajama in Bolivia) contain ice deposited during the Last Glacial Stage (LGS). The oxygen isotopic ratios (δ 18O) of this ice suggest significant tropical cooling ( ~5° C). Comparison of a global array of cores reveals large-scale similarities as well as important regional differences. The δ 18O shift from Early Holocene to LGM is 5.4‰ on Sajama, 6.3‰ on Huascarán, ~5.3‰ in central Greenland, 6.6‰ at Byrd Station in Antarctica and 5.4‰ at Vostok also in Antarctica. These records all show similar isotopic depletion, reflecting significant global cooling at the Late Glacial Maximum (LGM). As continental ice sheets form only in high latitudes (>40° ), those regions have provided most of the evidence for the pulsing of Quaternary glaciations. In low latitudes, glaciers are restricted to the high mountains and only recently have enough long tropical ice core histories become available to investigate the timing of glaciations there. Long ice cores recovered to bedrock at 7 high-altitude (>5300 m) sites on three continents are investigated for synchroneity of their glaciation histories. The cores from Huascarán in Peru at 9° S and Sajama in Bolivia at 18° S contain continuous records back into the LGS. Both glaciers clearly survived the early Holocene warm period (9 to 6 ka B.P.), but neither contains a long record of glacial stage climate back to the previous interglacial. Rather, the published records from Huascarán and Sajama extend back ~19 kyr and 25 kyr, respectively. Hence, both mountaintops, among the highest in South America, appear to have been ice free during a time considered significantly colder than the Holocene. The records from Dasuopu (28° N) and

  19. An ice core record of net snow accumulation and seasonal snow chemistry at Mt. Waddington, southwest British Columbia, Canada

    Science.gov (United States)

    Neff, P. D.; Steig, E. J.; Clark, D. H.; McConnell, J. R.; Pettit, E. C.; Menounos, B.

    2011-12-01

    We recovered a 141 m ice core from Combatant Col (51.39°N, 125.22°W, 3000 m asl) on the flank of Mt. Waddington, southern Coast Mountains, British Columbia, Canada. Aerosols and other impurities in the ice show unambiguous seasonal variations, allowing for annual dating of the core. Clustered melt layers, originating from summer surface heating, also aid in the dating of the core. Seasonality in water stable isotopes is preserved throughout the record, showing little evidence of diffusion at depth, and serves as an independent verification of the timescale. The annual signal of deuterium excess is especially well preserved. The record of lead deposition in the core agrees with those of ice cores from Mt. Logan and from Greenland, with a sharp drop-off in concentration in the 1970s and early 1980s, further validating the timescales. Despite significant summertime melt at this mid-latitude site, these data collectively reveal a continuous and annually resolved 36-year record of snow accumulation. We derived an accumulation time series from the Mt. Waddington ice core, after correcting for ice flow. Years of anomalously high or low snow accumulation in the core correspond with extremes in precipitation data and geopotential height anomalies from reanalysis data that make physical sense. Specifically, anomalously high accumulation years at Mt. Waddington correlate with years where "Pineapple Express" atmospheric river events bring large amounts of moisture from the tropical Pacific to western North America. The Mt. Waddington accumulation record thus reflects regional-scale climate. These results demonstrate the potential of ice core records from temperate glaciers to provide meaningful paleoclimate information. A longer core to bedrock (250-300 m) at the Mt. Waddington site could yield ice with an age of several hundred to 1000 years.

  20. Precipitation variations recorded in Guliya ice core in the past 400 years

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on the Guliya ice core records, the precipitation in the past 400 years was retrieved. Its rela tions with other regions were also analyzed. The results demonstrated that there were two high-precipitation periods and two low-precipitation periods in Guliya ice core since 1571 AD. The average precipitation in the two high-precipitation periods was 42 mm (21%) higher than that in the two low-precipitation periods. The precipitation recorded in the Guliya ice core was consistent with that in Dunde ice core. The variation trends of precipitation in the Guliya ice core and the northern hemisphere are similar. During the extremely wet years in the northern hemisphere, the precipitation recorded in the Guliya ice core was two times the long-term average. However, the annual precipitation was 38% less than that of the long-term average in extremely dry years.

  1. Carbonaceous aerosol tracers in ice-cores record multi-decadal climate oscillations.

    Science.gov (United States)

    Seki, Osamu; Kawamura, Kimitaka; Bendle, James A P; Izawa, Yusuke; Suzuki, Ikuko; Shiraiwa, Takayuki; Fujii, Yoshiyuki

    2015-09-28

    Carbonaceous aerosols influence the climate via direct and indirect effects on radiative balance. However, the factors controlling the emissions, transport and role of carbonaceous aerosols in the climate system are highly uncertain. Here we investigate organic tracers in ice cores from Greenland and Kamchatka and find that, throughout the period covered by the records (1550 to 2000 CE), the concentrations and composition of biomass burning-, soil bacterial- and plant wax- tracers correspond to Arctic and regional temperatures as well as the warm season Arctic Oscillation (AO) over multi-decadal time-scales. Specifically, order of magnitude decreases (increases) in abundances of ice-core organic tracers, likely representing significant decreases (increases) in the atmospheric loading of carbonaceous aerosols, occur during colder (warmer) phases in the high latitudinal Northern Hemisphere. This raises questions about causality and possible carbonaceous aerosol feedback mechanisms. Our work opens new avenues for ice core research. Translating concentrations of organic tracers (μg/kg-ice or TOC) from ice-cores, into estimates of the atmospheric loading of carbonaceous aerosols (μg/m(3)) combined with new model constraints on the strength and sign of climate forcing by carbonaceous aerosols should be a priority for future research.

  2. Grain size record of microparticles in the Muztagata ice core

    Institute of Scientific and Technical Information of China (English)

    WU; Guangjian; YAO; Tandong; XU; Baiqin; LI; Zheng; TIAN; Lide; DUAN; Keqin; WEN; Linke

    2006-01-01

    The dust transport and sediment characteristics are discussed based on analysis of microparticle size and size distribution in the Muztagata ice core at 6350 m a.s.l. The finer particles with diameter of 1―5μm are the dominant fraction in number, while middle and coarse particles mainly contribute to the total volume. The lognormal distribution characteristics can be seen for some high concentration samples, showing that model size and standard variation are greater than that in the Greenland ice cores. However, size-volume distribution of some low concentration samples is abnormal. Those distributions reflect the dust deposit process in high mountain glaciers at mid-low latitudes and show differences from those in polar ice sheet.

  3. A Pleistocene ice core record of atmospheric O2 concentrations

    Science.gov (United States)

    Stolper, D. A.; Bender, M. L.; Dreyfus, G. B.; Yan, Y.; Higgins, J. A.

    2016-09-01

    The history of atmospheric O2 partial pressures (PO2) is inextricably linked to the coevolution of life and Earth’s biogeochemical cycles. Reconstructions of past PO2 rely on models and proxies but often markedly disagree. We present a record of PO2 reconstructed using O2/N2 ratios from ancient air trapped in ice. This record indicates that PO2 declined by 7 per mil (0.7%) over the past 800,000 years, requiring that O2 sinks were ~2% larger than sources. This decline is consistent with changes in burial and weathering fluxes of organic carbon and pyrite driven by either Neogene cooling or increasing Pleistocene erosion rates. The 800,000-year record of steady average carbon dioxide partial pressures (PCO2) but declining PO2 provides distinctive evidence that a silicate weathering feedback stabilizes PCO2 on million-year time scales.

  4. Recent temperature increase recorded in an ice core in the source region of Yangtze River

    Institute of Scientific and Technical Information of China (English)

    KANG ShiChang; ZHANG YongJun; QIN DaHe; REN JiaWen; ZHANG QiangGong; Bjorn GRIGHOLM; Paul A. MAYEWSKI

    2007-01-01

    Interests on climate change in the source region of Yangtze River have been raised since it is a region with the greatest warming over the Tibetan Plateau (TP). A 70-year history of precipitation δ18O has been recovered using an ice core record retrieved in a plat portion of the firn area in the Guoqu Glacier (33°34′37.8″N, 91°10′35.32″E, 5720 m a.s.l.), Mt. Geladaindong (the source region of Yangtze River), in November, 2005. By using a significant positive relationship between ice core δ18O record and summer air temperature (July to September) from the nearby meteorological stations, a history of summer air temperature has been reconstructed for the last 70 years. Summer temperature was relatively low in 1940s and high in 1950s to the middle of 1960s. The lowest temperature occurred in the middle of 1970s.Temperature was low in 1980s and dramatically increased since 1990s, keeping the trend to the beginning of the 21st century. The warming rate recorded in the ice core with 0.5°C/10 a since 1970s is much higher that that in the central TP and the Northern Hemisphere (NH), and it becomes 1.1°C/10 a since 1990s which is also higher than these from the central TP and the NH, reflecting an accelerated warming and a more sensitive response to global warming in the high elevation region.

  5. Palaeomagnetic record from RH lacustrine core in Zoig■ Basin of Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    陈发虎; 王苏民; 李吉均; 施雅凤; 李世杰; 曹继秀; 张宇田; 王云飞; K.Kelts

    1995-01-01

    RH core,located in the Zoigê Basin of Eastern Tibetan Plateau,is a quite good lacustrinecore.It is 120.40m long.Nine geomagnetic excursions or events were recorded in the core during Brunhesnormal epoch based on measurement results of the remnant magnetization of small interval core samples(10cminterval)under series AF demagnetization,and organic carbon-14 and AMS dates.The excursions recorded bythe core can be correlated with those found in other regions in the world.They are the most detailed recordin lacustrine deposit in China.B/M boundary in the core is at the depth of 108.0m.It can be calculatedfrom the depositional rate of 0.13mm/a that the bottom age of the core is 825 ka B.P.The excursion ages inBrunhes and their correlation with those found in other regions are discussed.

  6. Human and climate impacts on Holocene fire activity recorded in polar and mountain ice cores

    Science.gov (United States)

    Kehrwald, Natalie; Zennaro, Piero; Kirchgeorg, Torben; Li, Quanlian; Wang, Ninglian; Power, Mitchell; Zangrando, Roberta; Gabrielli, Paolo; Thompson, Lonnie; Gambaro, Andrea; Barbante, Carlo

    2014-05-01

    Fire is one of the major influences of biogeochemical change on local to hemispheric scales through emitting greenhouse gases, altering atmospheric chemistry, and changing primary productivity. Levoglucosan (1,6-anhydro-β-D-glucopyranose) is a specific molecular that can only be produced by cellulose burning at temperatures > 300°C, comprises a major component of smoke plumes, and can be transported across > 1000 km distances. Levoglucosan is deposited on and archived in glaciers over glacial interglacial cycles resulting in pyrochemical evidence for exploring interactions between fire, climate and human activity. Ice core records provide records of past biomass burning from regions of the world with limited paleofire data including polar and low-latitude, high-altitude regions. Here, we present Holocene fire activity records from the NEEM, Greenland (77° 27'N; 51° 3'W; 2454 masl), EPICA Dome C, Antarctica (75° 06'S; 123° 21'E; 3233 masl), Kilimanjaro, Tanzania (3° 05'S, 21.2° E, 5893 masl) and the Muztagh, China (87.17° E; 36.35° N; 5780 masl ice cores. The NEEM ice core reflects boreal fire activity from both North American and Eurasian sources. Temperature is the dominant control of NEEM levoglucosan flux over decadal to millennial time scales, while droughts influence fire activity over sub-decadal timescales. Our results demonstrate the prominence of Siberian fire sources during intense multiannual droughts. Unlike the NEEM core, which incorporates the largest land masses in the world as potential fire sources, EPICA Dome C is located far from any possible fire source. However, EPICA Dome C levoglucosan concentrations are consistently above detection limits and demonstrate a substantial 1000-fold increase in fire activity beginning approximately 800 years ago. This significant and sustained increase coincides with Maori arrival and dispersal in New Zealand augmented by later European arrival in Australia. The EPICA Dome C levoglucosan profile is

  7. Atmospheric Pb variations in Central Asia since 1955 from Muztagata ice core record, eastern Pamirs

    Institute of Scientific and Technical Information of China (English)

    LI Zhen; YAO Tandong; TIAN Lide; XU Baiqing; LI Yuefang

    2006-01-01

    A Muztagata ice core recovered at 7010 m altitude in East Pamirs provides a Pb concentration record from 1955 to 2000. The result reveals increasing Pb concentrations from 1955 to 1993, with two Pb concentration peaks in 1980 and 1993. After 1993, Pb concentrations in ice core show an obviously declining trend. Analysis shows that the lead in the Muztagata ice core mainly came from anthropogenic emissions from countries in Central Asia, while the local emission had little contribution.

  8. A 21 000-year record of fluorescent organic matter markers in the WAIS Divide ice core

    Science.gov (United States)

    D'Andrilli, Juliana; Foreman, Christine M.; Sigl, Michael; Priscu, John C.; McConnell, Joseph R.

    2017-05-01

    Englacial ice contains a significant reservoir of organic material (OM), preserving a chronological record of materials from Earth's past. Here, we investigate if OM composition surveys in ice core research can provide paleoecological information on the dynamic nature of our Earth through time. Temporal trends in OM composition from the early Holocene extending back to the Last Glacial Maximum (LGM) of the West Antarctic Ice Sheet Divide (WD) ice core were measured by fluorescence spectroscopy. Multivariate parallel factor (PARAFAC) analysis is widely used to isolate the chemical components that best describe the observed variation across three-dimensional fluorescence spectroscopy (excitation-emission matrices; EEMs) assays. Fluorescent OM markers identified by PARAFAC modeling of the EEMs from the LGM (27.0-18.0 kyr BP; before present 1950) through the last deglaciation (LD; 18.0-11.5 kyr BP), to the mid-Holocene (11.5-6.0 kyr BP) provided evidence of different types of fluorescent OM composition and origin in the WD ice core over 21.0 kyr. Low excitation-emission wavelength fluorescent PARAFAC component one (C1), associated with chemical species similar to simple lignin phenols was the greatest contributor throughout the ice core, suggesting a strong signature of terrestrial OM in all climate periods. The component two (C2) OM marker, encompassed distinct variability in the ice core describing chemical species similar to tannin- and phenylalanine-like material. Component three (C3), associated with humic-like terrestrial material further resistant to biodegradation, was only characteristic of the Holocene, suggesting that more complex organic polymers such as lignins or tannins may be an ecological marker of warmer climates. We suggest that fluorescent OM markers observed during the LGM were the result of greater continental dust loading of lignin precursor (monolignol) material in a drier climate, with lower marine influences when sea ice extent was higher and

  9. Comparison of St. Elias Ice Core Accumulation Records and Their Relationships to Climate Indices

    Science.gov (United States)

    Yalcin, K.; Osterberg, E.; Mayewski, P.; Wake, C.; Kreutz, K.; Holdsworth, G.

    2006-12-01

    Recently recovered ice cores from the St Elias Mountains (Yukon) spanning an elevation range of three (Eclipse Icefield) to more than five kilometers (Mount Logan) offer a unique three-dimensional view of paleoclimate and environmental change in the North Pacific region. The record of net accumulation as deduced from the reconstruction of observed annual layer thicknesses in these cores offers a direct view of moisture flux at various altitudes in the St. Elias. However, a potentially large uncertainty in the representativeness of ice core accumulation records exists due to spatial variability in snow accumulation rates. The availability of multiple cores allows us to address this issue. Accumulation records from Eclipse (three cores) are highly reproducible with 78% of the signal shared between the three cores. The proportion of shared signal between accumulation records from the Logan plateau (Prospector-Russell Col and Northwest Col) is lower (52%). In this work we will compare the Eclipse and Logan accumulation records to each other to understand the spatial variability in net accumulation over time at different altitudes. The possible influence of dating errors on these results will be explored using leads and lags of 1-2 years. We also compare our accumulation records to indices of atmospheric circulation (e.g., strength of the Aleutian Low, the Pacific Decadal Oscillation, the El-Nino Southern Oscillation, Arctic Oscillation) to quantify relationships between snow accumulation and large-scale atmospheric circulation features on time-scales of variability ranging from years to centuries.

  10. The 1200 year composite ice core record of Aleutian Low intensification

    Science.gov (United States)

    Osterberg, E. C.; Winski, D. A.; Kreutz, K. J.; Wake, C. P.; Ferris, D. G.; Campbell, S.; Introne, D.; Handley, M.; Birkel, S.

    2017-07-01

    Future changes in North Pacific wintertime climate will be largely determined by the response of the Aleutian Low (ALow) pressure system to anthropogenic forcing. Although the ALow has intensified over the twentieth century, global climate model projections of future ALow variability are equivocal. In order to evaluate decadal to centennial ALow forcing mechanisms and provide context for the modern intensification, here we combine a new Denali ice core (Alaska) sea-salt sodium record with the Mount Logan ice core (Yukon) sodium record to develop a composite 1200 year record of ALow variability. The composite record indicates that the recent secular ALow intensification began circa 1741 and is unprecedented in magnitude and duration over the past millennium. North Pacific ice core snow accumulation and stable isotope records are consistent with this interpretation. The ALow intensification is associated with warming tropical Pacific sea surface temperatures, consistent with dynamic theory and instrumental correlations.

  11. Assessing Stationarity in Ice Core Record-Sea Level Pressure Relationships for Yukon Territory Ice Core Records

    Science.gov (United States)

    Kelsey, E. P.; Wake, C. P.; Osterberg, E. C.

    2014-12-01

    We assess the stationarity of the relationship between Northern Hemisphere winter (Dec-Feb) sea-level pressure (SLP) and proxy time series (major ions, accumulation, and stable isotopes) from the Eclipse (3017 m asl) and the Mt. Logan Prospector-Russell Col (PRCol; 5340 m asl) ice cores from Yukon, Canada. We develop a novel spatial calibration procedure to identify ranges of ice core values that are associated with consistent winter SLP anomaly patterns. Each ice core variable time series was ranked and divided into groups of 13 years each. We assess stationarity by splitting the 1872-2001 analysis period in half (1872-1936 and 1937-2001) and comparing the locations and magnitudes of SLP anomaly patterns during the two periods for each group of ice core values. Northern Hemisphere monthly mean SLP from the 20th Century Reanalysis dataset are used. The high accumulation rate (1.38 m a-1) at Eclipse allows us to analyze 6-month seasonal mean values (Oct-Mar and Apr-Sep), whereas annual mean values are used from PRCol where the accumulation rate is lower (0.40 m a-1). The Eclipse cold season accumulation and PRCol annual mean sodium concentrations (Na+) exhibit the strongest correlations with winter SLP anomaly patterns. In particular, the lowest and highest 20% annual Na+ values at PRCol and lowest 10% cold season accumulation values at Eclipse exhibit stationarity with consistent SLP anomaly patterns in the North Pacific for all three time periods. A weaker Aleutian Low consistently occurred in the central to eastern North Pacific for the lowest Na+ years at PRCol and lowest accumulation cold seasons at Eclipse, although these groups of years are mostly independent. A stronger Aleutian Low occurs in the North Pacific for the highest Na+ years at PRCol. A stationary SLP anomaly pattern is not observed through all three time periods for high cold season accumulation at Eclipse. Application of this calibration procedure with other traditional calibration and

  12. (129)I record of nuclear activities in marine sediment core from Jiaozhou Bay in China.

    Science.gov (United States)

    Fan, Yukun; Hou, Xiaolin; Zhou, Weijian; Liu, Guangshan

    2016-04-01

    Iodine-129 has been used as a powerful tool for environmental tracing of human nuclear activities. In this work, a sediment core collected from Jiaozhou Bay, the east coast of China, in 2002 was analyzed for (129)I to investigate the influence of human nuclear activities in this region. Significantly enhanced (129)I level was observed in upper 70 cm of the sediment core, with peak values in the layer corresponding to 1957, 1964, 1974, 1986, and after 1990. The sources of (129)I and corresponding transport processes in this region are discussed, including nuclear weapons testing at the Pacific Proving Grounds, global fallout from a large numbers of nuclear weapon tests in 1963, the climax of Chinese nuclear weapons testing in the early 1970s, the Chernobyl accident in 1986, and long-distance dispersion of European reprocessing derived (129)I. The very well (129)I records of different human nuclear activities in the sediment core illustrate the potential application of (129)I in constraining ages and sedimentation rates of the recent sediment. The releases of (129)I from the European nuclear fuel reprocessing plants at La Hague (France) and Sellafield (UK) were found to dominate the inventory of (129)I in the Chinese sediments after 1990, not only the directly atmospheric releases of these reprocessing plants, but also re-emission of marine discharged (129)I of these reprocessing plants in the highly contaminated European seas.

  13. A first shallow firn-core record from Glaciar La Ollada, Cerro Mercedario, central Argentine Andes

    Science.gov (United States)

    Bolius, David; Schwikowski, Margit; Jenk, Theo; Gäggeler, Heinz W.; Casassa, Gino; Rivera, Andrés

    In January 2003, shallow firn cores were recovered from Glaciar Esmeralda on Cerro del Plomo (33°14‧ S, 70°13‧ W; 5300 ma.s.l.), central Chile, and from Glaciar La Ollada on Cerro Mercedario (31°58‧ S, 70°07‧ W; 6070 ma.s.l.), Argentina, in order to find a suitable archive for paleoclimate reconstruction in a region strongly influenced by the El Niño-Southern Oscillation. In the area between 28° S and 35° S, the amount of winter precipitation is significantly correlated to the Southern Oscillation Index, with higher values during El Niño years. Glaciochemical analysis indicates that the paleo-record at Glaciar La Ollada is well preserved, whereas at Glaciar Esmeralda the record is strongly influenced by meltwater formation and percolation. A preliminary dating of the Mercedario core by annual-layer counting results in a time-span of 17 years (1986-2002), yielding an average annual net accumulation of 0.45 m w.e.

  14. Possible recent warming hiatus on the northwestern Tibetan Plateau derived from ice core records

    Science.gov (United States)

    An, Wenling; Hou, Shugui; Zhang, Wangbin; Wu, Shuangye; Xu, Hao; Pang, Hongxi; Wang, Yetang; Liu, Yaping

    2016-09-01

    Many studies have reported enhanced warming trend on the Tibetan Plateau (TP), even during the warming hiatus period. However, most of these studies are based on instrumental data largely collected from the eastern TP, whereas the temperature trend over the extensive northwestern TP remains uncertain due to few meteorological stations. Here we combined the stable isotopic δ18O record of an ice core recovered in 2012 from the Chongce glacier with the δ18O records of two other ice cores (i.e., Muztagata and Zangser Kangri) in the same region to establish a regional temperature series for the northwestern TP. The reconstruction shows a significant warming trend with a rate of 0.74 ± 0.12 °C/decade for the period 1970-2000, but a decreasing trend from 2001 to 2012. This is consistent with the reduction of warming rates during the recent decade observed at the only two meteorological stations on the northwestern TP, even though most stations on the eastern TP have shown persistent warming during the same period. Our results suggest a possible recent warming hiatus on the northwestern TP. This could have contributed to the relatively stable status of glaciers in this region.

  15. Holocene biomass burning recorded in polar and low-latitude ice cores

    Science.gov (United States)

    Kehrwald, N. M.; Zennaro, P.; Zangrando, R.; Gabrielli, P.; Thompson, L. G.; Gambaro, A.; Barbante, C.

    2011-12-01

    Ice cores contain specific molecular markers including levoglucosan (1,6-anhydro-β-D-glucopyranose) and other pyrochemical evidence that provides much-needed information on the role of fire in regions with no existing data of past fire activity. Levoglucosan is a cellulose combustion product produced at burning temperatures of 300°C or greater. We first trace fire emissions from a boreal forest source in the Canadian Shield through transport and deposition at Summit, Greenland. Atmospheric and surface samples suggest that levoglucosan in snow can record biomass burning events up to 1000s of kilometers away. Levoglucosan does degrade by interacting with hydroxyl radicals in the atmosphere, but it is emitted in large quantities, allowing the use as a biomass burning tracer. These quantified atmospheric biomass burning emissions and associated parallel oxalate and levoglucosan peaks in snow pit samples validates levoglucosan as a proxy for past biomass burning in snow records and by extension in ice cores. The temporal and spatial resolution of chemical markers in ice cores matches the core in which they are measured. The longest temporal resolution extends back approximately eight glacial cycles in the EPICA Dome C ice core, but many ice cores provide high-resolution Holocene records. The spatial resolution of chemical markers in ice cores depends on the core location where low-latitude ice cores primarily reflect regional climate parameters, and polar ice cores integrate hemispheric signals. Here, we compare levoglucosan flux measured during the late Holocene in the Kilimanjaro (3°04.6'S; 37°21.2'E, 5893 masl) and NEEM, Greenland (77°27' N; 51°3'W, 2454 masl) ice cores. We contrast the Holocene results with levoglucosan flux across the past 600,000 years in the EPICA Dome C (75°06'S, 123°21'E, 3233 masl) ice core.

  16. Accumulation in coastal West Antarctic ice core records and the role of cyclone activity

    Science.gov (United States)

    Hosking, J. Scott; Fogt, Ryan; Thomas, Elizabeth R.; Moosavi, Vahid; Phillips, Tony; Coggins, Jack; Reusch, David

    2017-09-01

    Cyclones are an important component of Antarctic climate variability, yet quantifying their impact on the polar environment is challenging. We assess how cyclones which pass through the Bellingshausen Sea affect accumulation over Ellsworth Land, West Antarctica, where we have two ice core records. We use self-organizing maps (SOMs), an unsupervised machine learning technique, to group cyclones into nine SOM nodes differing by their trajectories (1980-2015). The annual frequency of cyclones associated with the first SOM node (SOM1, which generally originate from lower latitudes over the South Pacific Ocean) is significantly (p 0.001) correlated with annual accumulation, with the highest seasonal correlations (p 0.001) found during autumn. While significant (p cyclones, we find no indication that this has led to an increase in moisture advection into, nor accumulation over, Ellsworth Land over this short time period.

  17. Records of volcanic events since AD 1800 in the East Rongbuk ice core from Mt. Qomolangma

    Institute of Scientific and Technical Information of China (English)

    XU JianZhong; KASPARI S.; HOU ShuGui; KANG ShiChang; QIN DaHe; REN JiaWen; MAYEWSKI p

    2009-01-01

    Continuous Bi profile of the East Rongbuk (ER) ice core near Mr.Qomolangma reveals nine major volcanic events since AD 1800.Compared with Volcanic Explosivity Index (VEI),it shows that the con-centrations of Bi in the ER ice core can reflect the major volcanic events within the key areas.This provides a good horizon layer for ice core dating,as well as a basis for reconstructing a long sequence of volcanic records from the Qinghai-Xizang (Tibet) Plateau ice cores.

  18. Climatic variations in the past 140 ka recorded in core RM, east Qinghai-Xizang Plateau

    Institute of Scientific and Technical Information of China (English)

    吴敬禄; 王苏民; 潘红玺; 夏威岚

    1997-01-01

    The sequences of climatic evolution are reconstructed by the analyses of δ13C and δ18O of carbonate from core RM in the Zoige Basin since 140 kaB. P. During the Last Glaciation there existed at least seven warm climatic fluctuations and five cold events correlated with the records of ice core and deep sea, and during the preceding last in-terglacial period there were two cold climatic variations coinciding with the record of ice core GRIP. These results depict climatic instability in east Qinghai-Xizang Plateau over the last interglacial period. In addition, the environmental proxies of the carbonate content and pigments indicate the similar results to the stable isotope record from core RM.

  19. Assessment of diffusive isotopic fractionation in polar firn, and application to ice core trace gas records

    DEFF Research Database (Denmark)

    Buizert, C.; Sowers, T.; Blunier, T.

    2013-01-01

    from ice cores; (5) arguably gives more accurate results than a combined firn densification-firn air transport modeling study would. We apply the method to records of CH, CO and NO mixing ratios, and we find that the correction is particularly important for C - . We apply the correction to C - records......During rapid variations of the atmospheric mixing ratio of a trace gas, diffusive transport in the porous firn layer atop ice sheets and glaciers alters the isotopic composition of that gas relative to the overlying atmosphere. Records of past atmospheric trace gas isotopic composition from ice...... cores and firn need to be corrected for this diffusive fractionation artifact. We present a novel, semi-empirical method to accurately estimate the magnitude of the diffusive fractionation in the ice core record. Our method (1) consists of a relatively simple analytical calculation; (2) requires only...

  20. Comparison between Greenland Ice-Margin an Ice-Core Oxygen-18 Records

    DEFF Research Database (Denmark)

    Reeh, Niels; Oerter, H.; Thomsen, H. Højmark

    2002-01-01

    or more records were obtained along closely spaced parallel sampling profiles, showing good reproducibility of the records. We present ice-margin delta(18)O records reaching back to the Pleistocene. Many of the characteristic delta(18)O variations known from Greenland deep ice cores can be recognized......Old ice for palaeoenvironmental studies retrieved by deep core drilling in the central regions of the large ice sheets can also be retrieved from the ice-sheet margins. The delta(18)O content of the surface ice was studied at 15 different Greenland ice-margin locations. At some locations, two...... at locations near the central ice divide. This is in accordance with deep ice-core results. We conclude that delta(18)O records measured on ice from the Greenland ice-sheet margin provide useful information about past climate and dynamics of the ice sheet, and thus are important (and cheap) supplements to deep...

  1. An ice-core-based record of biomass burning in the Arctic and Subarctic, 1750 1980

    Science.gov (United States)

    Whitlow, S.; Mayewski, P.; Dibb, J.; Holdsworth, G.; Twickler, M.

    1994-07-01

    Ammonium records from 3 ice cores, 20D and GISP2 (Greenland) and Mt. Logan (Yukon), covering the period from 1750 to the 1980s are analyzed. For each data set, samples with NH4+ concentrations greater than one standard deviation above the mean value also tend to be enriched in NO3 and K+, similar to the chemical composition of aerosols from aged biomass burning plumes. We believe the NH4+ spikes originate from biomass burning events. There is not a one to one correspondence between documented large fires and NH4+ spikes, nor are specific annual layers with elevated NH4+ concentrations often found in more than one core. However, frequency of NH4+ spikes increase during periods of more extensive and intensive biomass burning in the NH4+ source areas for the ice core sites. The 20D and GISP2 records are characterized by increased spike frequency from 1790 to 1810 and from 1830 to 1910. This latter time coincides with a period of increased biomass burning documented in the historical fire records for northern North America. In contrast to both Greenland ice core records, the Mt. Logan NH4+ record shows periods of increased spike frequency from 1770 1790, 1810 1830, 1850 1870 and 1930 1980. The poor agreement between the Mt. Logan record and the records from Greenland suggests that another source area, perhaps Siberia, may be the dominant summertime source area for NH4+ spikes in Mt. Logan snow.

  2. 150 kyr History of Arctic Black Carbon Deposition Recorded by Paired Ice Core and Sediment Core Records from Lake El'gygytgyn and NEEM

    Science.gov (United States)

    Chellman, N.; McConnell, J. R.; Heyvaert, A.; Brigham-Grette, J.; Melles, M.; Wennrich, V.; Svensson, A.

    2016-12-01

    Black carbon (BC) is a proxy for biomass burning and industrial combustion that has recently been recognized to have a major forcing on Earth's climate. The radiative effect of BC is most pronounced when BC is deposited onto highly reflective surfaces such as ice and snow and is estimated to have the third largest climate forcing after carbon dioxide and methane. Thus, quantifying BC in the climate system is crucial for modeling and understanding Earth's fire history and radiative budget. Here we present two long-term records of Northern Hemisphere BC deposition extending back 150 kyr. The first record, from the NEEM ice core, shows that BC deposition in Greenland is related to Northern Hemisphere climate and temperature proxies. The second record was obtained from a sediment core from Lake El'gygytgyn using a new method for BC measurements in lake sediments. The link between BC, insolation, and other climate proxies at these distant sites suggests a direct link between fire and climate that has been recorded in two distinct depositional environments. These two records capture both the local and regional BC signals that reflect fire emissions from different source regions and provide insight as to how climate affects BC deposition and, in turn, fire regime.

  3. Third Pole Glaciers and Ice Core Records of Past, Present and Future Climate

    Science.gov (United States)

    Thompson, L. G.; Yao, T.; Mosley-Thompson, E. S.; Davis, M. E.

    2011-12-01

    Ice core histories collected over the last two decades from across the Tibetan Plateau and the Himalaya demonstrate the climatic complexity and diversity of the Third Pole (TP) region. Proxy climate records spanning more than 500,000 years have been recovered from the Guliya ice cap in the far northwestern Kunlun Shan, which is dominated by westerly air flow over the Eurasian land mass. Shorter records (central TP, and also in the Himalaya to the south where a monsoonal climate regime dominates and the annual accumulation is high. The Himalayan ice fields are sensitive to fluctuations in the intensity of the South Asian Monsoon and are affected by the rising temperatures in the region. We examine the recent climatic changes to earlier distinctive epochs such as the Medieval Climate Anomaly (~950-1250 AD), the early Holocene "Hypsithermal" (~5 to 9 kyr BP) and the Eemian (~114 -130 kyr BP). The Eemian, the most recent period when Earth was significantly warmer than today, can serve in part as an analog for the coming greenhouse world. One thousand-year records of δ18O variations from four of these ice fields illustrate the effect of the recent warming across the TP. Mean values for much of the 20th Century (AD 1938 to 1987) are compared with those for the prior nine centuries (1000 to 1937 AD). The greatest recent enrichment occurs on the highest elevation site (Dasuopu in the Himalaya), presumably where the greatest warming is occurring. These trends are consistent with instrumental temperature records collected since the 1950s across the TP as well as with IPCC (2007) model predictions of a nearly two-fold vertical amplification of temperatures in the Tropics. A fifth ice field, Naimona'nyi (6100 masl), is not included in the study as recent melting from the top of the glacier has obliterated the upper 40 to 50 years of the record. Evidence confirming this will be presented along with recent mass balance measurements indicating that no net accumulation occurs on

  4. Influence of the Tungurahua eruption on the ice core records of Chimborazo, Ecuador

    Directory of Open Access Journals (Sweden)

    P. Ginot

    2010-08-01

    Full Text Available The comparison of two shallow ice cores recovered in 1999 and 2000 from the same place on Chimborazo summit glacier revealed the influence of the coincident Tungurahua volcanic eruption on their stable isotope and chemical records. The surface snow melting and water percolation induced from the ash deposition caused a preferential elution and re-localization of certain ionic species, while the stable isotope records were not very affected. Additionally, the comparison of the ionic amount and some selected ratios preserved along the ice core column reports under which processes the chemical species are introduced in the snow pack, as snow flake condensation nuclei, by atmospheric scavenging or by dry deposition. This preliminary study is essential for the interpretation of the deep Chimborazo ice core, or for other sites where surrounding volcanic activity may disturb the glaciochemical records.

  5. Influence of the Tungurahua eruption on the ice core records of Chimborazo, Ecuador

    Directory of Open Access Journals (Sweden)

    P. Ginot

    2010-12-01

    Full Text Available The comparison of two shallow ice cores recovered in 1999 and 2000 from the same place on the Chimborazo summit glacier revealed the influence of the coincident Tungurahua volcanic eruption on their stable isotope and chemical records. The surface snow melting and water percolation induced from the ash deposition caused a preferential elution and re-localization of certain ionic species, while the stable isotope records were not affected. Additionally, the comparison of the ionic amount and some selected ion ratios preserved along the ice core column reports under which processes the chemical species are introduced in the snow pack, as snow flake condensation nuclei, by atmospheric scavenging or by dry deposition. This preliminary study is essential for the interpretation of the deep Chimborazo ice core, or for other sites where surrounding volcanic activity influences the glaciochemical records.

  6. Bighorn Basin Coring Project (BBCP): High-Resolution Continental Records of Early Paleogene Hyperthermals

    Science.gov (United States)

    Clyde, W.; Wing, S.; Gingerich, P.

    2012-04-01

    Hyperthermals like the Paleocene-Eocene Thermal Maximum (PETM) are transient global warming events associated with large negative carbon isotope excursions (CIEs) that may serve as analogs to present-day climate change. Determining the causes and effects of hyperthermals is important for understanding the long-term carbon cycle and its effects on other parts of the Earth system. Most detailed stratigraphic records of hyperthermals come from marine sediment cores (e.g. IODP) with relatively few well-resolved continental stratigraphic records available. The Bighorn Basin is an intermontane basin that formed during the Laramide orogeny and experienced rapid subsidence and aggradational fluvial deposition from the early Paleocene through the early Eocene (~65-50 million years ago). It preserves the most complete early Paleogene continental sequence in the world and includes an approximately 40-meter-thick PETM interval During the summer of 2011, over 900 meters of core were recovered as part of the Bighorn Basin Coring Project (BBCP). Two 6.2-cm diameter overlapping cores were drilled at each of three sites. Two of the sites (Basin Substation and Polecat Bench) target the PETM in different environments, and the third site (Gilmore Hill) targets the younger and smaller hyperthermals known as ETM2 and H2. The BBCP cores make it possible to develop high-resolution (circa 1000-year) proxy records of climate change, carbon cycling, and biotic change from unweathered material to investigate the response of a terrestrial depositional and ecological system to extreme global warming events. The coring localities are also distributed along a transect from the margin to the axis of the basin to compare the tectonic and depositional effects on the hyperthermal records. Down-hole logs, multi-sensor core logs (magnetic susceptibility and color reflectance), visual core descriptions, and preliminary isotopic samples will be evaluated, with special emphasis on correlation to previous

  7. Arctic ice core records of vanillic acid from Siberia, Greenland, and Svalbard

    Science.gov (United States)

    Grieman, M. M.; Saltzman, E. S.; McConnell, J.; Fritzsche, D.; Opel, T.; Isaksson, E. D.; Schwikowski, M.

    2015-12-01

    Biomass burning is a major source for atmospheric gases and aerosols, and an important part of the global carbon cycle and radiation budget. The factors controlling centennial and millennial variability in regional to global biomass burning dynamics are not well understood because there are few well-dated proxy records only. We are exploring ice core records of organic compounds resulting from incomplete combustion of lignin as tracers for biomass burning. In this study we investigate the distribution of vanillic acid (VA) in Arctic ice cores. VA is a major product of conifer combustion, but may also be produced from angiosperms. VA was measured in ice core samples using ion chromatography with electrospray MS/MS detection. Here we present measurements of vanillic acid in three Arctic ice cores from Siberia (Akademii Nauk; 0-3 kyr bp), northern Greenland (Tunu; 0-1.75 kyr bp), and Svalbard (Lomonosovfonna; 0-0.75 kyr bp). The Siberian record exhibits 3 strong centennial scale maxima (1200-600 BC, AD 300-800, and AD 1450-1700). All three cores exhibit a smaller feature around 1250, with a subsequent decline in Greenland and Svalbard. VA levels in Greenland and Svalbard are generally smaller than those in Siberia. These results suggest strong regional input from Northern Eurasian sources (i.e. boreal forests) to the Siberian core, and lower Arctic-wide "background" levels at the other sites.

  8. The Laschamp geomagnetic excursion featured in nitrate record from EPICA-Dome C ice core

    Science.gov (United States)

    Traversi, R.; Becagli, S.; Poluianov, S.; Severi, M.; Solanki, S. K.; Usoskin, I. G.; Udisti, R.

    2016-01-01

    Here we present the first direct comparison of cosmogenic 10Be and chemical species in the period of 38–45.5 kyr BP spanning the Laschamp geomagnetic excursion from the EPICA-Dome C ice core. A principal component analysis (PCA) allowed to group different components as a function of the main sources, transport and deposition processes affecting the atmospheric aerosol at Dome C. Moreover, a wavelet analysis highlighted the high coherence and in-phase relationship between 10Be and nitrate at this time. The evident preferential association of 10Be with nitrate rather than with other chemical species was ascribed to the presence of a distinct source, here labelled as “cosmogenic”. Both the PCA and wavelet analyses ruled out a significant role of calcium in driving the 10Be and nitrate relationship, which is particularly relevant for a plateau site such as Dome C, especially in the glacial period during which the Laschamp excursion took place. The evidence that the nitrate record from the EDC ice core is able to capture the Laschamp event hints toward the possibility of using this marker for studying galactic cosmic ray flux variations and thus also major geomagnetic field excursions at pluri-centennial-millennial time scales, thus opening up new perspectives in paleoclimatic studies. PMID:26819064

  9. Deconvolution-based resolution enhancement of chemical ice core records obtained by continuous flow analysis

    DEFF Research Database (Denmark)

    Rasmussen, Sune Olander; Andersen, Katrine K.; Johnsen, Sigfus Johann

    2005-01-01

    Continuous flow analysis (CFA) has become a popular measuring technique for obtaining high-resolution chemical ice core records due to an attractive combination of measuring speed and resolution. However, when analyzing the deeper sections of ice cores or cores from low-accumulation areas......, there is still need for further improvement of the resolution. Here a method for resolution enhancement of CFA data is presented. It is demonstrated that it is possible to improve the resolution of CFA data by restoring some of the detail that was lost in the measuring process, thus improving the usefulness...

  10. Chernobyl nuclear accident revealed from the 7010 m Muztagata ice core record

    Institute of Scientific and Technical Information of China (English)

    TIAN LiDe; YAO TanDong; WU GuangJian; LI Zhen; XU BaiQing; LI YueFang

    2007-01-01

    The total activity variation with depth from a 41.6 m Muztagata ice core drilled at 7010 m,recorded not only the 1963 radioactive layer due to the thermonuclear test,but also clearly the radioactive peak released by the Chernobyl accident in 1986.This finding indicates that the Chernobyl nuclear accident was clearly recorded in alpine glaciers in the Pamirs of west China,and the layer can be potentially used for ice core dating in other high alpine glaciers in the surrounding regions.

  11. Vertical Sound Velocity Transition in the Coral Reef Core and its Significance of Indicating Facies

    Institute of Scientific and Technical Information of China (English)

    Li Ganxian; Lu Bo

    2002-01-01

    On the basis of the sound velocity measurements of the coral reef core from Nanyong No. 1 Well of Yongshu Reef in the Nansha Islands, the paper studies the relations between the vertical sound velocity transition features in the coral reef core and the corresponding stratigraphic depositional facies change as well as stratigraphic gap of erosion,analyses the cause of the sound velocity transition, expounds the concrete process of the sea level change resulting in the stratigraphic gap of erosion and facies change in the coral reef and explains the relations between the vertical sound velocity transition in the coral reef core and the corresponding stratigraphic paleoclimate and the sea level change. This study is of important practical value and theoretical significance to the island and reef engineering construction and the acoustic logging for oil exploration in the reef limestone area as well as the paleoceanographic study of the marginal sea in the western Pacific Ocean.

  12. Significant Broadband Photocurrent Enhancement by Au-CZTS Core-Shell Nanostructured Photocathodes.

    Science.gov (United States)

    Zhang, Xuemei; Wu, Xu; Centeno, Anthony; Ryan, Mary P; Alford, Neil M; Riley, D Jason; Xie, Fang

    2016-03-21

    Copper zinc tin sulfide (CZTS) is a promising material for harvesting solar energy due to its abundance and non-toxicity. However, its poor performance hinders their wide application. In this paper gold (Au) nanoparticles are successfully incorporated into CZTS to form Au@CZTS core-shell nanostructures. The photocathode of Au@CZTS nanostructures exhibits enhanced optical absorption characteristics and improved incident photon-to-current efficiency (IPCE) performance. It is demonstrated that using this photocathode there is a significant increase of the power conversion efficiency (PCE) of a photoelectrochemical solar cell of 100% compared to using a CZTS without Au core. More importantly, the PCE of Au@CZTS photocathode improved by 15.8% compared to standard platinum (Pt) counter electrode. The increased efficiency is attributed to plasmon resonance energy transfer (PRET) between the Au nanoparticle core and the CZTS shell at wavelengths shorter than the localized surface plasmon resonance (LSPR) peak of the Au and the semiconductor bandgap.

  13. Towards multi-decadal to multi-millennial ice core records from coastal west Greenland ice caps

    Science.gov (United States)

    Das, Sarah B.; Osman, Matthew B.; Trusel, Luke D.; McConnell, Joseph R.; Smith, Ben E.; Evans, Matthew J.; Frey, Karen E.; Arienzo, Monica; Chellman, Nathan

    2017-04-01

    The Arctic region, and Greenland in particular, is undergoing dramatic change as characterized by atmospheric warming, decreasing sea ice, shifting ocean circulation patterns, and rapid ice sheet mass loss, but longer records are needed to put these changes into context. Ice core records from the Greenland ice sheet have yielded invaluable insight into past climate change both regionally and globally, and provided important constraints on past surface mass balance more directly, but these ice cores are most often from the interior ice sheet accumulation zone, at high altitude and hundreds of kilometers from the coast. Coastal ice caps, situated around the margins of Greenland, have the potential to provide novel high-resolution records of local and regional maritime climate and sea surface conditions, as well as contemporaneous glaciological changes (such as accumulation and surface melt history). But obtaining these records is extremely challenging. Most of these ice caps are unexplored, and thus their thickness, age, stratigraphy, and utility as sites of new and unique paleoclimate records is largely unknown. Access is severely limited due to their high altitude, steep relief, small surface area, and inclement weather. Furthermore, their relatively low elevation and marine moderated climate can contribute to significant surface melting and degradation of the ice stratigraphy. We recently targeted areas near the Disko Bay region of central west Greenland where maritime ice caps are prevalent but unsampled, as potential sites for new multi-decadal to multi-millennial ice core records. In 2014 & 2015 we identified two promising ice caps, one on Disko Island (1250 m. asl) and one on Nuussuaq Peninsula (1980 m. asl) based on airborne and ground-based geophysical observations and physical and glaciochemical stratigraphy from shallow firn cores. In spring 2015 we collected ice cores at both sites using the Badger-Eclipse electromechanical drill, transported by a medley

  14. Recent Increases in Snow Accumulation and Decreases in Sea-Ice Concentration Recorded in a Coastal NW Greenland Ice Core

    Science.gov (United States)

    Osterberg, E. C.; Thompson, J. T.; Wong, G. J.; Hawley, R. L.; Kelly, M. A.; Lutz, E.; Howley, J.; Ferris, D. G.

    2013-12-01

    A significant rise in summer temperatures over the past several decades has led to widespread retreat of the Greenland Ice Sheet (GIS) margin and surrounding sea ice. Recent observations from geodetic stations and GRACE show that ice mass loss progressed from South Greenland up to Northwest Greenland by 2005 (Khan et al., 2010). Observations from meteorological stations at the U.S. Thule Air Force Base, remote sensing platforms, and climate reanalyses indicate a 3.5C mean annual warming in the Thule region and a 44% decrease in summer (JJAS) sea-ice concentrations in Baffin Bay from 1980-2010. Mean annual precipitation near Thule increased by 12% over this interval, with the majority of the increase occurring in fall (SON). To improve projections of future ice loss and sea-level rise in a warming climate, we are currently developing multi-proxy records (lake sediment cores, ice cores, glacial geologic data, glaciological models) of Holocene climate variability and cryospheric response in NW Greenland, with a focus on past warm periods. As part of our efforts to develop a millennial-length ice core paleoclimate record from the Thule region, we collected and analyzed snow pit samples and short firn cores (up to 20 m) from the coastal region of the GIS (2Barrel site; 76.9317 N, 63.1467 W) and the summit of North Ice Cap (76.938 N, 67.671 W) in 2011 and 2012, respectively. The 2Barrel ice core was sampled using a continuous ice core melting system at Dartmouth, and subsequently analyzed for major anion and trace element concentrations and stable water isotope ratios. Here we show that the 2Barrel ice core spanning 1990-2010 records a 25% increase in mean annual snow accumulation, and is positively correlated (r = 0.52, p<0.01) with ERA-Interim precipitation. The 2Barrel annual sea-salt Na concentration is strongly correlated (r = 0.5-0.8, p<0.05) with summer and fall sea-ice concentrations in northern Baffin Bay near Thule (Figure 1). We hypothesize that the positive

  15. Anthropogenic emissions and combustion products recorded in a Colle Gnifetti ice core

    Science.gov (United States)

    Gabrieli, J.; Kehrwald, N. M.; Zennaro, P.; Lim, S.; Laj, P.; Barbante, C.

    2012-12-01

    Ice cores provide direct and highly resolved records of atmospheric parameters that record both climate signals and forcing factors. European Alpine glaciers are located near densely populated and industrialized areas and provide excellent archives of past air pollution. Ice cores to bedrock on Colle Gnifetti, Monte Rosa (45°55'51''N, 07°52'34''E; 4450 m a.s.l.) permit centennial to millennial reconstruction of past regional climate, while snow pit and shallow core studies from the same site allow multiple parameter reconstructions of anthropogenic emissions. Air pollution includes fossil fuel and biomass burning products that influence regional smog and contain trace elements hazardous to human health. Here, we examine a high-resolution suite of anthropogenic and natural emissions (black carbon, levoglucosan, trace elements, heavy metals) and climate proxies (major ions and stable isotopes) in a 12 m Colle Gnifetti ice core to determine seasonal changes in anthropogenic emissions and their interaction with climate parameters. This is the first study to compare black carbon (a fossil fuel and biomass combustion tracer) with levoglucosan (a fire activity biomarker) in a European ice core. The combination of these two proxies can determine changing combustion product sources through time. Our results demonstrate that anthropogenic emissions influence the summer aerosol flux while crustal sources dominate the winter aerosol flux. These ice core chemical data are consistent with observational data and boundary layer dynamics that transport pollutants concentrated in the Po Valley and similar industrial lowland regions to glacier surfaces during the summer.

  16. Reconstruct Environmental Change through Reading Oxalate Records from the Ice Core

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ CAS scientists have made progress in investigating the past atmospheric changes by retrieving oxalate records from an ice core of Tianshan glaciers. An analysis shows that the variation of the organic acid mirrors the history of the regional economic development as well as environment protection in the west China over the past 40 years.

  17. Direct North-South synchronization of abrupt climate change record in ice cores using beryllium 10

    Directory of Open Access Journals (Sweden)

    G. M. Raisbeck

    2007-05-01

    Full Text Available A new, decadally resolved record of the 10Be peak at 41 kyr from the EPICA Dome C ice core (Antarctica is used to match it with the same peak in the GRIP ice core (Greenland. This permits a direct synchronisation of the climatic variations around 41 kyr BP, independent of uncertainties related to the ice age-gas age difference in ice cores. Dansgaard-Oeschger event 10 is in the period of best synchronisation and is found to be coeval with an Antarctic temperature maximum. Simulations using a thermal bipolar seesaw model agree reasonably well with the observed relative climate chronology in these two cores. They also reproduce three Antarctic warming events between A1 and A2.

  18. Direct north-south synchronization of abrupt climate change record in ice cores using Beryllium 10

    Directory of Open Access Journals (Sweden)

    G. M. Raisbeck

    2007-09-01

    Full Text Available A new, decadally resolved record of the 10Be peak at 41 kyr from the EPICA Dome C ice core (Antarctica is used to match it with the same peak in the GRIP ice core (Greenland. This permits a direct synchronisation of the climatic variations around this time period, independent of uncertainties related to the ice age-gas age difference in ice cores. Dansgaard-Oeschger event 10 is in the period of best synchronisation and is found to be coeval with an Antarctic temperature maximum. Simulations using a thermal bipolar seesaw model agree reasonably well with the observed relative climate chronology in these two cores. They also reproduce three Antarctic warming events observed between A1 and A2.

  19. Synchronizing the North American Varve Chronology with Greenland ice core records during late MIS 2 using Meteoric 10Be Flux

    Science.gov (United States)

    DeJong, Benjamin D.; Balco, Greg; Ridge, Jack C.; Rood, Dylan H.; Bierman, Paul R.

    2013-04-01

    The North American Varve Chronology (NAVC) is a floating 5700-year sequence of glacial lake varves deposited in the Connecticut River Valley of the northeast US ~18,000-12,500 years ago. The NAVC is an annually resolved record of regional climate and ice-marginal processes at 40-45° N latitude, near the margin of the retreating Laurentide Ice Sheet (LIS). NAVC deposition occurred at the same time as rapid and abrupt Arctic and North Atlantic climate changes that took place during the last deglaciation. Age calibration estimates for the NAVC based on radiocarbon dated plant macrofossils in individual varves imply a relationship between ice-marginal events recorded by the NAVC and climate events recorded in Greenland ice cores. For example, the retreat rate of the LIS up the Connecticut River Valley increased during the Bolling warming in Greenland, a readvance of the LIS margin took place during the Older Dryas cold period, and a correlation between an outburst flood from glacial Lake Iroquois and the Intra-Allerod Cold Period supports the hypothesis that the flood affected North Atlantic thermohaline circulation. On the other hand, a doubling of the ice-margin retreat rate recorded by the NAVC around 16,000 years ago coincides with a relatively cold period in Greenland. Our goal is to investigate the precise time relationship between these two records by synchronizing the NAVC with the Greenland ice core time scale using atmospherically-produced 10Be. Existing 10Be flux records, including those from Greenland ice cores, exhibit solar variability on a range of time scales. Because this variability is globally synchronous, a 10Be flux record for the NAVC can, in principle, be used to align NAVC and ice core timescales. In the first phase of this research we tested this potential by generating 10Be flux records for two 80-year varve sequences and analyzing them using multi-taper spectral analysis for determination of statistically significant periodicities. We were

  20. Climatic variations since the Little Ice Age recorded in the Guliya Ice Core

    Institute of Scientific and Technical Information of China (English)

    姚檀栋; 焦克勤; 田立德; 杨志红; 施维林; Lonnie G. Thompson

    1996-01-01

    The climatic variations since the Little Ice Age recorded in the Guliya Ice Core are discussed based on glacial δ18O and accumulation records in the Guliya Ice Core. Several obvious climate fluctuation events since 1570 can be observed according to the records. In the past 400 years, the 17th and 19th centuries are relatively cool periods with less precipitation, and the 18th and 20th centuries are relatively warm periods with high precipitation. The study has also revealed the close relationship between temperature and precipitation on the plateau. Warming corresponds to high precipitation and cooling corresponds to less precipitation, which is related with the influence of monsoon on this region.

  1. Synchronizing the North American Varve Chronology with Greenland ice core records using meteoric 10Be flux

    Science.gov (United States)

    DeJong, B.; Balco, G.; Ridge, J. C.; Rood, D. H.; Bierman, P. R.

    2012-12-01

    The North American Varve Chronology (NAVC) is a floating 5700-year sequence of glacial lake varves deposited in the Connecticut River Valley of the northeast US ~18,000-12,500 years ago. The NAVC is an annually resolved record of regional climate and ice-marginal processes at 40-45° N latitude, near the margin of the retreating Laurentide Ice Sheet (LIS). NAVC deposition occurred at the same time as rapid and abrupt Arctic and North Atlantic climate changes that took place during the last deglaciation. An age estimate for the NAVC based on radiocarbon dated plant macrofossils in individual varves implies a relationship between ice-marginal events recorded by the NAVC and climate events recorded in Greenland ice cores. For example, the retreat rate of the LIS up the Connecticut River Valley increased during the Bolling warming in Greenland, a readvance of the LIS margin took place during the Older Dryas cold period, and a correlation between an outburst flood from glacial Lake Iroquois and the Intra-Allerod Cold Period supports the hypothesis that the flood affected North Atlantic thermohaline circulation. On the other hand, a doubling of the ice-margin retreat rate recorded by the NAVC around 16,000 years ago coincides with a relatively cold period in Greenland. Our goal is to investigate the precise time relationship between these events by synchronizing the NAVC with the Greenland ice core time scale using atmospherically-produced 10Be. Existing 10Be flux records, including those from Greenland ice cores, exhibit solar variability on a range of time scales. Because this variability is globally synchronous, a 10Be flux record for the NAVC can, in principle, be used to align NAVC and ice core timescales. We are generating such a record at present. First, we are analyzing short varve sections at high temporal resolution to evaluate the magnitude of solar variability signals; a single section analyzed so far displays interannual variability with a period consistent

  2. Climate variation since the Last Interglaciation recorded in the Guliya ice core

    Institute of Scientific and Technical Information of China (English)

    姚檀栋; L.G.Thompson; 施雅风; 秦大河; 焦克勤; 杨志红; 田立德; E.M.Thompson

    1997-01-01

    The climatic and environmental variations since the Last Interglaciation are reconstructed based on the study of the upper 268 m of the 309-m-long Guliya ice core. Five stages can be distinguished since the Last Interglaciation from the δ18O record in the Guliya ice core: Stage 1 (Deglaciation), Stage 2 (the Last Glacial Maximum), Stage 3 (interstadial), Stage 4 (interstadial in the early glacial maximum) and Stage 5 (the Last Interglaciation). Stage 5 can be divided further into 5 substages; a, b, c, d, e. The δ18O record in the Guliya ice core indicates clearly the close correlation between the temperature variation on the Tibetan Plateau and the solar activities. The study indicates that the solar activity is a main forcing to the climatic variation on the Tibetan Plateau. Through a comparison of the ice core record in Guliya with that in the Greenland and the Antarctic, it can be found that the variation of large temperature variation events in different parts of the world is generally the same, b

  3. The ice-core record of volcanism: Status and future directions

    Science.gov (United States)

    Sigl, Michael; McConnell, Joseph R.; Chellman, Nathan; Ludlow, Francis; Curran, Mark; Plunkett, Gill; Büntgen, Ulf; Toohey, Matthew; Burke, Andrea; Grieman, Mackenzie

    2016-04-01

    Radiative forcing resulting from stratospheric aerosols produced by major volcanic eruptions is a dominant driver of climate variability in the Earth's past. Accurate knowledge of the climate anomalies resulting from volcanic eruptions provides important information for understanding the global and regional responses of the Earth system to external forcing agents. Based on a unique compilation of newly obtained, high-resolution, ice-core measurements, as well as palaeo-climatic evidence inferred from existing tree-ring records and historical documentary sources, we revised the dating of ice-core based reconstructions of past volcanic eruptions and confirmed the dominant role of explosive volcanism on short-term summer temperature variability throughout the past 2,500 years. Continuous weekly surface snow measurements obtained from Summit, Greenland (2005-2014) further allow placing volcanic sulphate emissions arising from a series of moderate volcanic eruptions during the last decade into a multi-millennial context. While these updated ice core records provide a more accurate constraint on the timing and magnitude of volcanic eruptions, there is also new data emerging on the geographic locations of past eruptions, atmospheric transport of volcanic fallout and climatic consequences (e.g. sea-ice; hydro-climate) from studying volcanic deposits (e.g. extent of volcanic ash deposition), proxy data and historical records. On the basis of selected case studies we will discuss the role volcanic eruptions have played in the Earth's climate system during the past and identify potential additional constraints provided by ice cores.

  4. Representativeness and seasonality of major ion records derived from NEEM firn cores

    Directory of Open Access Journals (Sweden)

    G. Gfeller

    2014-10-01

    Full Text Available The seasonal and annual representativeness of ionic aerosol proxies (among others, calcium, sodium, ammonium and nitrate in various firn cores in the vicinity of the NEEM drill site in northwest Greenland have been assessed. Seasonal representativeness is very high as one core explains more than 60% of the variability within the area. The inter-annual representativeness, however, can be substantially lower (depending on the species making replicate coring indispensable to derive the atmospheric variability of aerosol species. A single core at the NEEM site records only 30% of the inter-annual atmospheric variability in some species, while five replicate cores are already needed to cover approximately 70% of the inter-annual atmospheric variability in all species. The spatial representativeness is very high within 60 cm, rapidly decorrelates within 10 m but does not diminish further within 3 km. We attribute this to wind reworking of the snow pack leading to sastrugi formation. Due to the high resolution and seasonal representativeness of the records we can derive accurate seasonalities of the measured species for modern (AD 1990–2010 times as well as for pre-industrial (AD 1623–1750 times. Sodium and calcium show similar seasonality (peaking in February and March respectively for modern and pre-industrial times, whereas ammonium and nitrate are influenced by anthropogenic activities. Nitrate and ammonium both peak in May during modern times, whereas during pre-industrial times ammonium peaked during July–August and nitrate during June–July.

  5. The role of variability in atmospheric circulation and Greenland precipitation for interpreting ice core records

    Science.gov (United States)

    Faber, Anne-Katrine; Li, Camille

    2017-04-01

    Ice cores from Greenland contain the layers of snowfall accumulated throughout each year. Variability in snowfall accumulation can therefore influence the climatic signal recorded in the ice cores. This study uses reanalysis data from ERA-Interim (1979-2015) to investigate how atmospheric circulation patterns can drive precipitation and accumulation variability on the Greenland Ice Sheet. This is examined by comparing the spatial and temporal variability in precipitation amount and frequency with specific phases of atmospheric patterns such as the North Atlantic Circulation (NAO) as well as with the position of the North Atlantic jet stream. Results show that large-scale atmospheric conditions associated with high precipitation events in northwestern Greenland (near the ice core site NEEM) differ from the atmospheric conditions associated with high precipitation events in northeastern Greenland (near the ice core site EGRIP). The relationship between the large-scale conditions and moisture transport paths are investigated to determine how this precipitation variability arises. A further understanding of the atmospheric circulation patterns role in the precipitation variability and high precipitation events can help to improve the interpretation of the ice core records for past and present-day climates.

  6. Representativeness and seasonality of major ion records derived from NEEM firn cores

    Science.gov (United States)

    Gfeller, G.; Fischer, H.; Bigler, M.; Schüpbach, S.; Leuenberger, D.; Mini, O.

    2014-10-01

    The seasonal and annual representativeness of ionic aerosol proxies (among others, calcium, sodium, ammonium and nitrate) in various firn cores in the vicinity of the NEEM drill site in northwest Greenland have been assessed. Seasonal representativeness is very high as one core explains more than 60% of the variability within the area. The inter-annual representativeness, however, can be substantially lower (depending on the species) making replicate coring indispensable to derive the atmospheric variability of aerosol species. A single core at the NEEM site records only 30% of the inter-annual atmospheric variability in some species, while five replicate cores are already needed to cover approximately 70% of the inter-annual atmospheric variability in all species. The spatial representativeness is very high within 60 cm, rapidly decorrelates within 10 m but does not diminish further within 3 km. We attribute this to wind reworking of the snow pack leading to sastrugi formation. Due to the high resolution and seasonal representativeness of the records we can derive accurate seasonalities of the measured species for modern (AD 1990-2010) times as well as for pre-industrial (AD 1623-1750) times. Sodium and calcium show similar seasonality (peaking in February and March respectively) for modern and pre-industrial times, whereas ammonium and nitrate are influenced by anthropogenic activities. Nitrate and ammonium both peak in May during modern times, whereas during pre-industrial times ammonium peaked during July-August and nitrate during June-July.

  7. Representativeness and seasonality of major ion records derived from NEEM firn cores

    Directory of Open Access Journals (Sweden)

    G. Gfeller

    2014-05-01

    Full Text Available The seasonal and annual representativeness of ionic aerosol proxies (among others, calcium, sodium, ammonium and nitrate in various firn cores in the vicinity of the NEEM drill site in north-west Greenland have been assessed. Seasonal representativeness is very high as one core explains more than 60% of the variability within the area. The inter-annual representativeness, however, can be substantially lower (depending on the species making replicate coring indispensable to derive the atmospheric variability of aerosol species. A single core at the NEEM site records only 30% of the inter-annual atmospheric variability in some species, while five replicate cores are already needed to cover approximately 70% of the inter-annual atmospheric variability in all species. The spatial representativeness is very high within 60 cm, rapidly decorrelates within 10 m but does not diminish further within 3 km. We attribute this to wind reworking of the snow pack leading to sastrugi formation. Due to the high resolution and seasonal representativeness of the records we can derive accurate seasonalities of the measured species for modern times as well as for pre-industrial times. Sodium and calcium show similar seasonality (peaking in February and March respectively for modern and pre-industrial times, whereas ammonium and nitrate are influenced by anthropogenic activities. Nitrate and ammonium both peak in May during modern times, whereas during pre-industrial times ammonium peaked during July–August and nitrate during June–July.

  8. A 290-a record of atmospheric circulation over the North Pacific from a Mt. Logan ice core, Yukon Territory

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Calibrations between sodium (Na+) concentrations from a Mt. Logan ice core and sea level pressure (SLP) series show that Na+ concentrations are closely correlated with the autumn-time (SeptemberOctober-November) Aleutian low (AleuLow). A deepening of the AleuLow strengthens the transport of sea-salt aerosols from the North Pacific to the Mt. Logan region. The Mt. Logan Na+ record is used to develop a 292 a (1688~1979) reconstruction of the AleuLow revealing a dramatic intensification of atmospheric circulation over the North Pacific region since the 20th century. Mean SLP of the AleuLow was about 1 hPa lower during the 20th century than during prior periods. The strongest deepening of the AleuLow appeared in the 1950s. Significant correlations are also found between the Mt. Logan AleuLow proxy series and the Pacific decadal oscillation (PDO) and Pacific circulation (PC) index during the 20th century. Evolutionary spectral analysis of the proxy record shows significant periodicities from 15 to 30 a consistent with PDO fluctuations and the bidecadal oscillation of North Pacific atmosphere-ocean circulation. A period of 11 a in the AleuLow record may be associated with the Schwabe 11-a cycle of sunspot activity. Additional longer ice core records from this region will aid in the efforts to further understand the climatic change over the North Pacific region.

  9. East Antarctic ice sheet stability recorded in a high-elevation ice-cored moraine

    Science.gov (United States)

    Bader, Nicole A.; Licht, Kathy J.; Kaplan, Michael R.; Kassab, Christine; Winckler, Gisela

    2017-03-01

    Till in an extensive blue ice moraine in the central Transantarctic Mountains at Mt. Achernar shows relatively continuous deposition by East Antarctic derived ice throughout the last glacial cycle. The most recently exposed material along the active margin of the Law Glacier (Zone 1) has hummocky topography that transitions into to a relatively flat region (Zone 2), followed by a series of ∼2 m high continuous, parallel/sub-parallel ridges and troughs (Zones 3-5). The entire moraine is ice-cored. Past surface changes of data, the U-Pb zircon data from till across all zones show little variability and are consistent with a Beacon Supergroup source, as samples show significant populations from the Proterozoic, ∼550-600 Ma and ∼950-1270 Ma, as well as the late Archean ∼2700-2770 Ma. The Mackellar, Fairchild, and lower Buckley Formations are interpreted as dominant sources of the detrital zircons. The zircon data lack the spatio-temporal variability indicated by the pebble fraction because the local Ferrar dolerite is not zircon bearing, highlighting the broader importance of using multiple techniques when interpreting provenance changes over time. Rather than reflecting major changes in ice flow path over time, the provenance changes are interpreted to indicate relative stability of the East Antarctic ice sheet, as the Law Glacier tapped into and eroded successively lower stratigraphic units of the Beacon Supergroup. This has important implications for interpreting offshore provenance records.

  10. Evidence for general instability of past climate from a 250-KYR ice-core record

    DEFF Research Database (Denmark)

    Johnsen, Sigfus Johann; Clausen, Henrik Brink; Dahl-Jensen, Dorthe

    1993-01-01

     results1,2 from two ice cores drilled in central Greenland have revealed large, abrupt climate changes of at least regional extent during the late stages of the last glaciation, suggesting that climate in the North Atlantic region is able to reorganize itself rapidly, perhaps even within a few...... decades. Here we present a detailed stable-isotope record for the full length of the Greenland Ice-core Project Summit ice core, extending over the past 250 kyr according to a calculated timescale. We find that climate instability was not confined to the last glaciation, but appears also to have been...... marked during the last interglacial (as explored more fully in a companion paper3) and during the previous Saale-Holstein glacial cycle. This is in contrast with the extreme stability of the Holocene, suggesting that recent climate stability may be the exception rather than the rule. The last...

  11. Annually resolved ice core records of tropical climate variability over the past ~1800 years.

    Science.gov (United States)

    Thompson, L G; Mosley-Thompson, E; Davis, M E; Zagorodnov, V S; Howat, I M; Mikhalenko, V N; Lin, P-N

    2013-05-24

    Ice cores from low latitudes can provide a wealth of unique information about past climate in the tropics, but they are difficult to recover and few exist. Here, we report annually resolved ice core records from the Quelccaya ice cap (5670 meters above sea level) in Peru that extend back ~1800 years and provide a high-resolution record of climate variability there. Oxygen isotopic ratios (δ(18)O) are linked to sea surface temperatures in the tropical eastern Pacific, whereas concentrations of ammonium and nitrate document the dominant role played by the migration of the Intertropical Convergence Zone in the region of the tropical Andes. Quelccaya continues to retreat and thin. Radiocarbon dates on wetland plants exposed along its retreating margins indicate that it has not been smaller for at least six millennia.

  12. Integration of ice core, marine and terrestrial records: new insights into Holocene atmospheric circulation dynamics over NW Europe

    Science.gov (United States)

    Muschitiello, F.; Hammarlund, D.; Wohlfarth, B.

    2012-12-01

    We analyzed the oxygen (δ18O) and carbon (δ13C) isotope composition of lacustrine carbonates (Chara sp. and Bithynia tentaculata) from a lake sediment sequence (Lake Bjärsträsk) on the island of Gotland, southern Sweden. Our new isotopic records show a significant consistency with existing regional climatic reconstructions, as well as with paleorecords reflecting large-scale circulation dynamics. By comparing our data to ice core records from Greenland and to regional- and global-scale terrestrial and marine climate records, we explore potential couplings of Mid- and Late Holocene extreme summer climate conditions in northwestern Europe to orbital forcing and low-latitude atmospheric circulation dynamics. Specifically, we discuss the relationship between long-term changes in the position of the North Atlantic subtropical front and the frequency of summer blocking anticyclones over southern Sweden. Furthermore, we tentatively outline the spatial structure of predominant modes of atmospheric variability over the North Atlantic sector throughout the Holocene.

  13. A 60-year ice-core record of regional climate from Adélie Land, coastal Antarctica

    Science.gov (United States)

    Goursaud, Sentia; Masson-Delmotte, Valérie; Favier, Vincent; Preunkert, Susanne; Fily, Michel; Gallée, Hubert; Jourdain, Bruno; Legrand, Michel; Magand, Olivier; Minster, Bénédicte; Werner, Martin

    2017-02-01

    A 22.4 m-long shallow firn core was extracted during the 2006/2007 field season from coastal Adélie Land. Annual layer counting based on subannual analyses of δ18O and major chemical components was combined with 5 reference years associated with nuclear tests and non-retreat of summer sea ice to build the initial ice-core chronology (1946-2006), stressing uncertain counting for 8 years. We focus here on the resulting δ18O and accumulation records. With an average value of 21.8 ± 6.9 cm w.e. yr-1, local accumulation shows multi-decadal variations peaking in the 1980s, but no long-term trend. Similar results are obtained for δ18O, also characterised by a remarkably low and variable amplitude of the seasonal cycle. The ice-core records are compared with regional records of temperature, stake area accumulation measurements and variations in sea-ice extent, and outputs from two models nudged to ERA (European Reanalysis) atmospheric reanalyses: the high-resolution atmospheric general circulation model (AGCM), including stable water isotopes ECHAM5-wiso (European Centre Hamburg model), and the regional atmospheric model Modèle Atmosphérique Régional (AR). A significant linear correlation is identified between decadal variations in δ18O and regional temperature. No significant relationship appears with regional sea-ice extent. A weak and significant correlation appears with Dumont d'Urville wind speed, increasing after 1979. The model-data comparison highlights the inadequacy of ECHAM5-wiso simulations prior to 1979, possibly due to the lack of data assimilation to constrain atmospheric reanalyses. Systematic biases are identified in the ECHAM5-wiso simulation, such as an overestimation of the mean accumulation rate and its interannual variability, a strong cold bias and an underestimation of the mean δ18O value and its interannual variability. As a result, relationships between simulated δ18O and temperature are weaker than observed. Such systematic

  14. Mount Logan ice core record of tropical and solar influences on Aleutian Low variability: 500-1998 A.D.

    Science.gov (United States)

    Osterberg, Erich C.; Mayewski, Paul A.; Fisher, David A.; Kreutz, Karl J.; Maasch, Kirk A.; Sneed, Sharon B.; Kelsey, Eric

    2014-10-01

    Continuous, high-resolution paleoclimate records from the North Pacific region spanning the past 1500 years are rare; and the behavior of the Aleutian Low (ALow) pressure center, the dominant climatological feature in the Gulf of Alaska, remains poorly constrained. Here we present a continuous, 1500 year long, calibrated proxy record for the strength of the wintertime (December-March) ALow from the Mount Logan summit (PR Col; 5200 m asl) ice core soluble sodium time series. We show that ice core sodium concentrations are statistically correlated with North Pacific sea level pressure and zonal wind speed. Our ALow proxy record reveals a weak ALow from circa 900-1300 A.D. and 1575-1675 A.D., and a comparatively stronger ALow from circa 500-900 A.D., 1300-1575 A.D., and 1675 A.D. to present. The Mount Logan ALow proxy record shows strong similarities with tropical paleoclimate proxy records sensitive to the El Niño-Southern Oscillation and is consistent with the hypothesis that the Medieval Climate Anomaly was characterized by more persistent La Niña-like conditions while the Little Ice Age was characterized by at least two intervals of more persistent El Niño-like conditions. The Mount Logan ALow proxy record is significantly (p < 0.05) correlated and coherent with solar irradiance proxy records over various time scales, with stronger solar irradiance generally associated with a weaker ALow and La Niña-like tropical conditions. However, a step-like increase in ALow strength during the Dalton solar minimum circa 1820 is associated with enhanced Walker circulation. Furthermore, rising CO2 forcing or internal variability may be masking the twentieth century rise in solar irradiance.

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

    Science.gov (United States)

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

    2014-12-01

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

  16. Changes in black carbon deposition to Antarctica from two high-resolution ice core records, 1850–2000 AD

    Directory of Open Access Journals (Sweden)

    M. M. Bisiaux

    2012-05-01

    Full Text Available Refractory black carbon aerosols (rBC emitted by biomass burning (fires and fossil fuel combustion, affect global climate and atmospheric chemistry. In the Southern Hemisphere (SH, rBC is transported in the atmosphere from low- and mid-latitudes to Antarctica and deposited to the polar ice sheet preserving a history of emissions and atmospheric transport. Here, we present two high-resolution Antarctic rBC ice core records drilled from the West Antarctic Ice Sheet divide and Law Dome on the periphery of the East Antarctic ice sheet. Separated by ~3500 km, the records span calendar years 1850–2001 and reflect the rBC distribution over the Indian and Pacific ocean sectors of the Southern Ocean. Concentrations of rBC in the ice cores displayed significant variability at annual to decadal time scales, notably in ENSO-QBO and AAO frequency bands. The delay observed between rBC and ENSO variability suggested that ENSO does not directly affect rBC transport, but rather continental hydrology, subsequent fire regimes, and aerosol emissions. From 1850 to 1950, the two ice core records were uncorrelated but were highly correlated from 1950 to 2002 (cross-correlation coefficient at annual resolution: r = 0.54, p < 0.01 due to a common decrease in rBC variability. The decrease in ice-core rBC from the 1950s to late 1980s displays similarities with inventories of SH rBC grass fires and biofuel emissions, which show reduced emission estimates over that period.

  17. Ice core record of rising lead pollution in the North Pacific atmosphere

    Science.gov (United States)

    Osterberg, E.; Mayewski, P.; Kreutz, K.; Fisher, D.; Handley, M.; Sneed, S.; Zdanowicz, C.; Zheng, J.; Demuth, M.; Waskiewicz, M.; Bourgeois, J.

    2008-03-01

    A high-resolution, 8000 year-long ice core record from the Mt. Logan summit plateau (5300 m asl) reveals the initiation of trans-Pacific lead (Pb) pollution by ca. 1730, and a >10-fold increase in Pb concentration (1981-1998 mean = 68.9 ng/l) above natural background (5.6 ng/l) attributed to rising anthropogenic Pb emissions from Asia. The largest rise in North Pacific Pb pollution from 1970-1998 (end of record) is contemporaneous with a decrease in Eurasian and North American Pb pollution as documented in ice core records from Greenland, Devon Island, and the European Alps. The distinct Pb pollution history in the North Pacific is interpreted to result from the later industrialization and less stringent abatement measures in Asia compared to North America and Eurasia. The Mt. Logan record shows evidence for both a rising Pb emissions signal from Asia and a trans-Pacific transport efficiency signal related to the strength of the Aleutian Low.

  18. North Pacific Climate Variability in Ice Core Accumulation Records From Eclipse Icefield, Yukon, Canada

    Science.gov (United States)

    Yalcin, K.; Wake, C. P.; Kreutz, K. J.

    2005-12-01

    Three annually dated ice cores from Eclipse Icefield, Yukon, Canada provide records of net accumulation spanning the last 100 to 500 years. The ice cores were dated by annual layer counting verified by reference horizons provided by radioactive fallout and volcanic eruptions. Annual layers become progressively thinner with depth in the Eclipse ice cores, requiring reconstruction of original annual layer thicknesses by correcting for ice creep. An empirical approach was used that is based on the observed layer thicknesses from annual layer counting of the Eclipse ice cores. Accumulation records are highly reproducible with 73% of the signal shared between the three cores. The accumulation time-series shows considerable decadal scale variability that can be related to climate regimes that characterize the North Pacific. For example, periods of high accumulation are noted from 1470-1500, 1540-1560, and 1925-1975. Periods of low accumulation are observed between 1500-1540, 1680-1780, and 1875-1925. The strongest multi-year drop in accumulation is seen between 1979 and 1984, although there are isolated years with lower accumulation. This drop in accumulation is possibly related to the 1977 regime shift in the Pacific Decadal Oscillation. However, PDO regime shifts are not always reflected in the accumulation time series, implying a non-linear response or modulation by other modes of climate variability such as ENSO. Its is noteworthy that the Eclipse accumulation time series is out of phase with the accumulation time series from nearby Mount Logan on all time scales for reasons to be investigated.

  19. Mt. Logan Ice Core Record of North Pacific Holocene Climate Variability

    Science.gov (United States)

    Osterberg, E. C.; Mayewski, P. A.; Fisher, D. A.; Kreutz, K. J.; Handley, M. J.; Sneed, S. B.

    2006-12-01

    A >12,000 year-long, continuous, high-resolution (sub-annual to multi-decadal) ice core record from the summit plateau (5300 m asl) of Mt. Logan, Yukon, Canada, reveals large, abrupt fluctuations in North Pacific climate throughout the Holocene with a 1-2 ky periodicity. Co-registered major ion, trace element and stable isotope time series reveal a strong inverse relationship between precipitation δ18O and atmospheric seasalt and dust concentrations over multi-decadal to millennial periods (rMt. Logan represent changes in moisture source region between dominantly cold North Pacific waters (more zonal circulation; enriched stable isotope values) and warmer subtropical waters (more meridional circulation; depleted stable isotope values). Consequently, Holocene millennial-scale stable isotope fluctuations in the Mt. Logan core have a larger amplitude (6-9‰ for δ18O) than those found in Greenland and Canadian Arctic ice core records (e.g. 2-3‰ for GISP2 δ18O). Over the instrumental period (1948-1998), higher Mt. Logan dust concentrations are strongly associated with enhanced springtime cyclonic activity over East Asian desert source regions (rMt. Logan seasalt aerosol concentrations are related to the wintertime strength of the Aleutian Low pressure center (r<-0.45, p<0.001). We use these calibrated proxy relationships to propose a conceptual model of North Pacific atmospheric circulation during the Holocene.

  20. Ice core precipitation record in central Tibetan plateau since AD 1600

    Directory of Open Access Journals (Sweden)

    T. Yao

    2008-02-01

    Full Text Available Lack of reliable long-term precipitation record from northern Tibetan Plateau has constrained the understanding of precipitation variation in this region. An ice core drilled from the Puruogangri Ice Field on central Tibetan Plateau in the year 2000 helped reveal the precipitation variations since AD 1600. Analysis of the annual accumulation data presented precipitation changes from AD 1600, indicative of wet and dry periods in the past 400 year in the central Tibetan Plateau. Accordingly, the 18th and 20th centuries experienced high precipitation period, whilst the 19th century experienced low precipitation period. Such a feature was consistent with precipitation recorded in ice cores from Dunde and Guliya Glaciers, northern Tibetan Plateau. Besides, the results also pointed to consistency in precipitation-temperature correlation on the northern Tibetan Plateau, in a way that temperature and precipitation were positively correlated. But this feature was contrary to the relationship revealed from Dasuopu ice cores, southern Tibetan Plateau, where temperature and precipitation were negatively correlated. The north-south contrast in precipitation amount and its relationship with temperature may shed light on the reconstruction of Asian monsoon since AD 1600.

  1. A Multi-Core Parallelization Strategy for Statistical Significance Testing in Learning Classifier Systems.

    Science.gov (United States)

    Rudd, James; Moore, Jason H; Urbanowicz, Ryan J

    2013-11-01

    Permutation-based statistics for evaluating the significance of class prediction, predictive attributes, and patterns of association have only appeared within the learning classifier system (LCS) literature since 2012. While still not widely utilized by the LCS research community, formal evaluations of test statistic confidence are imperative to large and complex real world applications such as genetic epidemiology where it is standard practice to quantify the likelihood that a seemingly meaningful statistic could have been obtained purely by chance. LCS algorithms are relatively computationally expensive on their own. The compounding requirements for generating permutation-based statistics may be a limiting factor for some researchers interested in applying LCS algorithms to real world problems. Technology has made LCS parallelization strategies more accessible and thus more popular in recent years. In the present study we examine the benefits of externally parallelizing a series of independent LCS runs such that permutation testing with cross validation becomes more feasible to complete on a single multi-core workstation. We test our python implementation of this strategy in the context of a simulated complex genetic epidemiological data mining problem. Our evaluations indicate that as long as the number of concurrent processes does not exceed the number of CPU cores, the speedup achieved is approximately linear.

  2. A 600-year annual 10Be record from the NGRIP ice core, Greenland

    DEFF Research Database (Denmark)

    Berggren, A.M.; Johnsen, Sigfus Johann; Vinther, Bo Møllesøe

    2009-01-01

    Despite the extensive use of 10Be as the most significant information source on past solar activity, there has been only one record (Dye-3, Greenland) providing annual resolution over several centuries. Here we report a new annual resolution 10Be record spanning the period 1389-1994 AD, measured...

  3. EPICA Dome C ice core fire record demonstrates a major biomass burning increase over the past 500 years

    Science.gov (United States)

    Kehrwald, Natalie; Power, Mitchell; Zennaro, Piero; McWethy, David; Whitlock, Cathy; Zangrando, Roberta; Gambaro, Andrea; Barbante, Carlo

    2013-04-01

    Natural factors and human activity influence fire variability including changes in temperature and precipitation, increasing greenhouse gas concentrations, altering ignitions, vegetation cover and fuel availability. Ice cores archive chemical signatures of both past climate and fire activity, and understanding this interaction is increasingly important in a warming climate. The specific molecular marker levoglucosan (1,6-anhydro-ß-D-glucopyranose) can only be produced by burning woody tissue at temperatures greater than 300°C. Levoglucosan is present in the fine fraction of smoke plumes, is transported distances of thousands of kilometers, is deposited on glacier surfaces, and is detectable in both polar and mountain ice cores providing an unambiguous fire history. Here, we present a high-resolution 10,000-year levoglucosan record in the EPICA Dome C (75°06'S, 123°21'E, 3233 masl) ice core and implications for determining natural and human-caused fire variability. A recent provocative hypothesis by Ruddiman suggests that humans may have had a significant impact on the Earth's climate thousands of years ago through carbon and methane emissions originating from biomass burning associated with early agriculture. This hypothesis is centered on the observation that atmospheric carbon dioxide and methane levels recorded in ice cores increased irrespective of insolation changes beginning 7,000 to 5,000 years before present. The EDC levoglucosan record does not demonstrate augmented fire activity at 5000 and/or 7000 years ago in the Southern Hemisphere. We are currently determining Holocene levoglucosan concentrations in the NEEM, Greenland (77°27' N; 51°3'W, 2454 masl) ice core to provide a Northern Hemisphere comparison at 5000 and/or 7000 years ago. The highest EDC Holocene fire activity occurs during the past 500 years. Mean levoglucosan concentrations between 500 to 10,000 BP are approximately 50 ppt, but rise to 300 ppt at present. This substantial increase is

  4. Anthropogenic signals recorded in an ice core from Eclipse Icefield, Yukon Territory, Canada

    Science.gov (United States)

    Yalcin, Kaplan; Wake, Cameron P.

    Trends in the annual flux of sulfate and nitrate in a new ice core collected at an elevation of 3017 m on Eclipse Icefield, 45 km northeast of Mt. Logan were examined to determine the effect of anthropogenic activity on precipitation chemistry in the remote northwest North America mid-troposphere. The annual flux of both sulfate and nitrate at Eclipse began increasing in the 1940s, demonstrating, for the first time, the anthropogenic sulfate and nitrate pollution of the northwest North American Arctic in an ice core from this region. Comparison of the Eclipse record with regional emission estimates for total sulfur and nitrogen oxides suggests that Eurasia is the dominant source of pollutants reaching Eclipse. The available data does not permit a confident assessment of the relative importance of European versus Soviet emissions in producing the observed trends in sulfate and nitrate at Eclipse.

  5. Using giant piston coring within IODP to track past earthquakes in the sedimentary record along the Japan Trench

    Science.gov (United States)

    Strasser, Michael

    2017-04-01

    ), the mid-slope terraces and (ii) from representative slope sites as potential source for sediment remobilization during earthquakes (2) nearly 2000km of high-resolution subbottom acoustic reflection data (Parasound) that reveals striking, up to several meter thick, acoustically transparent bodies interbedded in the otherwise parallel reflection pattern of the trench fill basins. Results from conventional coring covering the last 1500 years reveal good agreement between the sedimentary record and historical documents in the central part of the margin, and shed new lights on earthquake-triggered, gravity flow-driven supply of significant amount of pre-aged carbon to the hadal environment. New cores retrieved from the southern and northernmost part of the Japan Trench during the recent R/V Sonne expedition SO251 confirm the presence of repeated thick turbidite sequences to be further tested for correlation to historic earthquakes along different margin segments. All these observations underpin the great potential for deciphering earthquake related processes from the stratigraphic record of the small deep-sea trench-fill and graben-fill basins in the Japan Trench, the longer-term record of which is only accessible by giant-piston coring and drilling, as proposed by IODP in Proposal 866.

  6. Paleoseismic record obtained by coring a sag-pond along the North Anatolian Fault (Turkey

    Directory of Open Access Journals (Sweden)

    Aurelia Hubert-Ferrari

    2013-01-01

    Full Text Available Shallow lakes along minor structural bends or discontinuities of strike-slip faults are not usually paleoseismological target sites. In the present study, we show that a 2-m-deep, 700-m-long lake that is cross-cut by the North Anatolian Fault contains a reliable paleoseimological record that can be obtained through coring. The North Anatolian Fault is a major strike-slip fault in Turkey, and it last ruptured across the Aşağıtepecik Lake in 1939, with a slip of about 6 m. Seismic lines still show remains of the fault rupture in the form of minor scarps across the lake. Collected short cores show a set of sedimentary sequences. Each sequence is composed of similar organic-rich sedimentary units. The lower unit is dark and fibrous, and is similar to the present sedimentation at the top of the core. The upper unit is disturbed and has anomalous organic matter content, grain size and mineralogy. It is interpreted as an earthquake-induced sedimentary event. The 2.5-m-long AT2007LG core comprises four sequences, and four sedimentary events. Radiogenic 210Pb and 137Cs data obtained previously imply that the shallowest event 1 was triggered by the 1939 M = 7.9 Erzincan earthquake. Radiocarbon dating and correlation to a reference varved record suggest that events 2 and 4 were initiated by the 1668 and 1254 historical earthquakes. Event 3 does not correspond to a large historical earthquake on the North Anatolian Fault.

  7. Multi-decadal variability in the Greenland ice core records obtained using intrinsic timescale decomposition

    Science.gov (United States)

    Zhou, Jiansong; Tung, Ka-Kit; Li, King-Fai

    2016-08-01

    By performing a new adaptive time series decomposition on the composite average of multiple ice core records obtained from the Arctic and Greenland, we extracted a robust quasi-oscillatory signal with a period of ~70 years throughout the preceding millennium, and showed that it is strongly connected to the Atlantic Multidecadal Oscillation (AMO). In the same decomposition there exists the Greenland signature of the Little Ice Age and Medieval Warm Period. Throughout the warm and cold periods the AMO properties remained robust. It implies that the evolution of the AMO has its own coherent mechanism and was little affected by these large climatic excursions.

  8. High-frequency paleoclimatic variability: a spectral analysis of the Vostok ice-core isotopic record

    Energy Technology Data Exchange (ETDEWEB)

    Yiou, P.; Genthon, C.; Jouzel, J.; Le Treut, H.; Lorius, C.; Ghil, M.; Korotkevich, Y.S.

    1988-01-01

    This paper uses a recently analysed isotopic record from an ice core drilled at the Soviet Antartic Station VOSTOK, representing a total time span of about 160,000 years. Results obtained show the existence of a significative climatic variability at the time scale of 10,000 years and below. The many spectral peaks appear to be approximate linear combination of a little number among them, a clear indication of the non linear nature of climate fluctuations at these ''short'' time scales.

  9. Possible recording of the Mono Lake Excursion in cored sediment from Clear Lake, California

    Science.gov (United States)

    Liddicoat, Joseph; Verosub, Kenneth

    2010-05-01

    We report the possible recording of the Mono Lake Excursion (MLE) in cored sediment from Clear Lake, CA. The locality (39.0˚N, 237.3˚E) is about 120 km north of San Francisco, CA, and 320 km northwest of the Mono Basin, CA, where the MLE first was discovered in North America (Denham and Cox, 1971). The field behaviour at Clear Lake that might be the MLE is recorded in clay and peaty clay about 50 cm below the top of the lowermost 80-cm core slug of a 21.6-m core. The coring was done by the wire-line method (Sims and Rymer, 1975) and the samples (rectangular solids 21 mm on a side and 15 mm high) were measured in a cryogenic magnetometer after demagnetization in an alternating field to 35 milliTesla (Verosub, 1977). The continuously-spaced samples record negative inclination of nearly 20˚ and northerly declination when unnormalized relative field intensity was reduced by an order of magnitude from the mean value. Those palaeomagnetic directions are followed immediately by positive inclination to about 50˚ and easterly declination of about 60˚ when the field intensity is at a relative high. That pattern of behaviour is recorded at three localities (Wilson Creek, Mill Creek, and Warm Springs) in the Mono Basin at the MLE (Liddicoat and Coe, 1979; Liddicoat, 1992). A path of the Virtual Geomagnetic Poles (VGPs) at Clear Lake form a clockwise-trending loop that is centered at 65˚N, 20˚E in the hemisphere away from the locality. The VGP that is farthest from the North Geographic Pole is at 29.3˚N, 337.1˚E, which is close to the path formed by the VGPs in the older portion of the MLE (Liddicoat and Coe, 1979; Liddicoat, 1992). The age of the sediment recording the anomalous palaeomagnetic directions in Clear Lake is about 30,000 years B.P. (Verosub, 1977). That age was determined from six (uncalibrated) radiocarbon dates, three of which are from near the base of the core (Sims and Rymer, 1975) where there are the anomalous palaeomagnetic directions, and linear

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

    Science.gov (United States)

    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.

  11. Magnetic records of Core MD77-181 in the Bay of Bengal and their paleoenvironmental implications

    Institute of Scientific and Technical Information of China (English)

    LI Haiyan; ZHANG Shihong; FANG Nianqiao; WANG Hongqiang

    2006-01-01

    High-resolution environmental magnetic measurements were carried out on Core MD77-181 in the Bay of Bengal, including magnetic susceptibility, anhysteretic remanent magnetization, isothermal remanent magnetization of all samples, and temperature-dependence of magnetic susceptibilities and magnetic hysteresis parameters of representative samples. The results suggest that (1) the magnetic mineral assemblage of the upper 9.82 m sediments (corresponding to the last 160 ka) is dominated by pseudo-single domain magnetite, with more abundant coarse grains in glacial periods than in interglacial periods; (2) the uppermost 6.50 m of sediments (corresponding to the last 70 ka) shows significant temporal variations in grain sizes of magnetic minerals, possibly reflecting the teleconnection between variations of the Indian summer monsoon and rapid cold events of the North Atlantic (Heinrich events); (3) the sediments below 9.82 m are dominated by paramagnetic minerals (probably including pyrites), suggesting reductive diagenesis. The magnetic records of Core MD77-181 are comparable to those of Core MD77-180 in the Bay of Bengal, and ODP Hole 722B in the Arabian Sea. This study suggests that the paleoceanographic event at ~160 ka significantly changed the redox state of the northern Indian Ocean, from a reductive environment before the event to an oxic or suboxic environment after the event.

  12. Greenland NEEM ice core records of As, Cd, Cr and Mo during the period of 1820-1970 AD

    Science.gov (United States)

    Lee, K.; Han, Y.; Moon, J.; Hur, S. D.; Hong, S.

    2016-12-01

    Greenland snow and ice core records of various trace elements showed that the large -scale atmospheric cycles of these elements have been strongly modified by human activities. However, such snow and ice core records are only available for the very few elements such as lead (Pb), copper (Cu), zinc (Zn), cadmium (Cd), and thallium (Tl), because concentrations of most of elements in Greenland snow and ice are extremely low at the low and sub-pg/g level. We here present an annual resolution record of changes in the occurrence of arsenic (As), chromium (Cr), molybdenum (Mo) and Cd from Greenland NEEM ice core samples covering the period from 1820 to1970. To our knowledge, long-term trends of As, Cr, and Mo have never been reconstructed from Greenland ice cores at such a high resolution. Barium (Ba) was also analyzed to calculate the crustal enrichment factors (EFc), using concentration ratios between the four trace elements and Ba in the samples and in the mean upper continental crust. Concentrations of As, Cd, Cr and Mo are 1.3 80.4 pg/g, 0.005 21.2 pg/g, 4.3 98.3 pg/g and 0.1 6.4 pg/g, respectively. To help emphasize the main features of anthropogenic inputs, individual data points were averaged for a decadal period, while the whole data before 1850 were averaged as the preindustrial period. All the measured elements show two distinct peaks in concentrations, but contrasting situations are observed for the different elements. As and Cd show a rapid increase in concentrations from 1870 to 1880s and from 1930 to 1940s, while Cr and Mo show peaks during the 1900s and 1960s. The temporal trends of the EFs appear to match with those of concentrations for each element. The different patterns in the periods reaching peaks in concentrations and EFs are likely due to the primary anthropogenic sources for the different element. Anthropogenic As and Cd are mainly emitted from non-ferrous metals production, while Cr and Mo are from fossil fuel combustion. Our first comprehensive

  13. High-resolution sedimentary record of hydrocarbon contaminants in a core from the major reaches of the Pearl River, China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The concentrations and compositions of hydrocarbon contaminants, and molecularmarker indices in modern sediments from a core in the major reaches of the Pearl River were investigated. The sedimentary record of hydrocarbons in the core, in combination with 210pb-dating,was used to reconstruct the pollution history of hydrocarbon pollutants in the Pearl River in the past 100 years.

  14. INTegrating Ice core, MArine, and TErrestrial records (COST Action ES0907)

    Science.gov (United States)

    Hoek, Wim; Rasmussen, Sune; Renssen, Hans; Hajdas, Irka; Brauer, Achim; Blockley, Simon; Svensson, Anders; Moreno, Ana; Roche, Didier; Valdes, Paul; Birks, Hilary; Solveig Seidenkrantz, Marit; Evelpidou, Niki

    2013-04-01

    The objective of INTIMATE is to reconstruct past abrupt and extreme climate changes over the period 60,000 to 8000 years ago, by facilitating INTegration of Ice core, MArine, and TErrestrial palaeoclimate records and using the combined data in climate models to better understand the mechanisms and impact of change, thereby reducing the uncertainty of future prediction. The project is organized in four working groups: WG-1 Dating and Chronological Modelling A reliable chronological framework is the basis of all studies of the past climate. WG1 is dedicated to developing and improving dating methods over the last 60,000 years and bringing scientists together to develop a coherent dating framework in which records can be compared at unprecedented detail. WG-2 Quantification of Past Climate The aim of WG-2 is to collect and quantify information of past climate from e.g. ice cores, tree rings, corals, stalagmites, and marine and lake sediments in order to draw a detailed picture of the highly variable climate evolution in the North Atlantic region. WG-3 Modelling Mechanisms of Past Change Our ability to forecast the rates and magnitudes of future change depends on numerical models. By using combined ice core, terrestrial, and marine data sets as targets, WG-3 will optimize methodologies to evaluate model simulations and make data-model comparisons. WG-4 Climate Impacts The aim of WG-4 is to gain insights into the impacts of past climatic changes on animal and human populations and the ecosystems of which they are part. WG-4 will quantify the magnitudes and rates of population, species, and ecosystem responses to climate events of different magnitudes in space and through time. The INTIMATE network and the workshops and meetings are open to all interested scientists. INTIMATE also supports research exchange visits. More information can be found at http://cost-es0907.geoenvi.org/

  15. Retrieving a common accumulation record from Greenland ice cores for the past 1800 years

    DEFF Research Database (Denmark)

    Andersen, Katrine K.; Ditlevsen, Peter D.; Rasmussen, Sune Olander;

    2006-01-01

    climate signal in the different accumulation records through optimization of the ratio between the variance of the common signal and of the residual. Using this model, a common Greenland accumulation record for the past 1800 years has been extracted. The record shows significant 11.9 years periodicity....... A sharp transition to very dry conditions is found just before A.D. 1200, and very dry conditions during the 13th century together with dry and cold spells during the 14th century may have put extra strain on the Norse population in Greenland and may have contributed to their extinction. Accumulation...

  16. Accumulation reconstruction and water isotope analysis for 1735–1997 of an ice core from the Ushkovsky volcano, Kamchatka, and their relationships to North Pacific climate records

    Directory of Open Access Journals (Sweden)

    T. Sato

    2013-04-01

    Full Text Available To investigate past climate change in the Northwest Pacific region, an ice core was retrieved in June 1998 from the Gorshkov crater glacier at the top of the Ushkovsky volcano, in central Kamchatka. Hydrogen isotope (δD analysis and past accumulation reconstructions were conducted to a depth of 140.7 m, dated to 1735. Two accumulation reconstruction methods were applied with the Salamatin and the Elmer/Ice ice flow models. Reconstructed accumulation rates and δD were significantly correlated with North Pacific surface temperature. This, and a significant correlation of δD with the North Pacific Gyre Oscillation (NPGO index implies that NPGO data is contained in this record. Wavelet analysis shows that the ice core records have significant multi-decadal power spectra up to the late 19th century. The multi-decadal periods of reconstructed accumulation rates change at around 1850 in the same way as do Northeast Pacific ice core and tree ring records. The loss of multi-decadal scale power spectra of δD and the 6‰ increase in its average value occurred around 1880. Thus the core record confirms that the periodicity of precipitation for the entire North Pacific changed between the end of the Little Ice Age through the present due to changes in conditions in the North Pacific Ocean.

  17. Characterization of Solanum tuberosum multicystatin and the significance of core domains.

    Science.gov (United States)

    Green, Abigail R; Nissen, Mark S; Kumar, G N Mohan; Knowles, N Richard; Kang, Chulhee

    2013-12-01

    Potato (Solanum tuberosum) multicystatin (PMC) is a unique cystatin composed of eight repeating units, each capable of inhibiting cysteine proteases. PMC is a composite of several cystatins linked by trypsin-sensitive (serine protease) domains and undergoes transitions between soluble and crystalline forms. However, the significance and the regulatory mechanism or mechanisms governing these transitions are not clearly established. Here, we report the 2.2-Å crystal structure of the trypsin-resistant PMC core consisting of the fifth, sixth, and seventh domains. The observed interdomain interaction explains PMC's resistance to trypsin and pH-dependent solubility/aggregation. Under acidic pH, weakening of the interdomain interactions exposes individual domains, resulting in not only depolymerization of the crystalline form but also exposure of cystatin domains for inhibition of cysteine proteases. This in turn allows serine protease-mediated fragmentation of PMC, producing ∼ 10-kD domains with intact inhibitory capacity and faster diffusion, thus enhancing PMC's inhibitory ability toward cysteine proteases. The crystal structure, light-scattering experiments, isothermal titration calorimetry, and site-directed mutagenesis confirmed the critical role of pH and N-terminal residues in these dynamic transitions between monomer/polymer of PMC. Our data support a notion that the pH-dependent structural regulation of PMC has defense-related implications in tuber physiology via its ability to regulate protein catabolism.

  18. Characterization of Solanum tuberosum Multicystatin and the Significance of Core Domains[C

    Science.gov (United States)

    Green, Abigail R.; Nissen, Mark S.; Kumar, G.N. Mohan; Knowles, N. Richard; Kang, ChulHee

    2013-01-01

    Potato (Solanum tuberosum) multicystatin (PMC) is a unique cystatin composed of eight repeating units, each capable of inhibiting cysteine proteases. PMC is a composite of several cystatins linked by trypsin-sensitive (serine protease) domains and undergoes transitions between soluble and crystalline forms. However, the significance and the regulatory mechanism or mechanisms governing these transitions are not clearly established. Here, we report the 2.2-Å crystal structure of the trypsin-resistant PMC core consisting of the fifth, sixth, and seventh domains. The observed interdomain interaction explains PMC’s resistance to trypsin and pH-dependent solubility/aggregation. Under acidic pH, weakening of the interdomain interactions exposes individual domains, resulting in not only depolymerization of the crystalline form but also exposure of cystatin domains for inhibition of cysteine proteases. This in turn allows serine protease–mediated fragmentation of PMC, producing ∼10-kD domains with intact inhibitory capacity and faster diffusion, thus enhancing PMC’s inhibitory ability toward cysteine proteases. The crystal structure, light-scattering experiments, isothermal titration calorimetry, and site-directed mutagenesis confirmed the critical role of pH and N-terminal residues in these dynamic transitions between monomer/polymer of PMC. Our data support a notion that the pH-dependent structural regulation of PMC has defense-related implications in tuber physiology via its ability to regulate protein catabolism. PMID:24363310

  19. Formate and acetate records in the Muztagata ice core,Northwest Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG Junxia; YAO Tandong; XU Baiqing; WU Guangjian; XIANG Shurong

    2004-01-01

    Formate and acetate concentrations are measured in a 22.56 m-depth ice core recovered in Mt. Muztagata Glacier, northwest Tibetan Plateau. The mean concentrations for formate and acetate in this ice core are 186.6±160.1 and 136.4±133.9 rng/g, respectively. Study shows that there is a positive correlation between formate and nitrate, suggesting both continental origins. However, no significant relationship has been found between formate and acetate, though they both have obvious periodical variations. Because Mt. Muztagata lies in the mid-latitude and is correlative to the nearby human activities, formate and acetate concentrations are higher than those in Greenland and Antarctica. During recent decades, the increase of formate concentration in the Muztagata ice core and formaldehyde production shows a close correlation. We preliminarily presume that the high formate concentration in the Muztagata ice core is concerned with the thriving of house decoration in which excess formaldehyde was used.

  20. Comparison of a 1500 Year-Long ENSO-Sensitive Ice Core Proxy Record to Modeled Solar Forcing Mechanisms

    Science.gov (United States)

    Osterberg, E.; Mayewski, P.; Kreutz, K.; Fisher, D.; Sneed, S.

    2008-12-01

    A calibrated 1500 year-long glaciochemical proxy record for the strength of the wintertime (November-March) Aleutian Low (ALOW) from the Mt. Logan summit (PR Col; 5300 m a.s.l.) ice core [Na+] time series reveals a strong ALOW from ca. 650-900 A.D., ca. 1300-1550 A.D., and ca. 1700-1998 A.D., and a weaker ALOW from ca. 900-1300 A.D. and ca. 1550-1700 A.D. The proxy record was calibrated to instrumental sea-level pressure data using standard regression techniques, and verified using statistical, spectral, and spatial correlation analyses. This record is consistent with ENSO-sensitive paleoclimate proxies from the Pacific basin that indicate El Niño-like conditions during the Little Ice Age (LIA) and La Niña- like conditions during the so-called Medieval Climate Anomaly (MCA). The Mt. Logan ALOW proxy record is significantly correlated with atmospheric Δ14C records (r = 0.39, p<0.05), supporting an influence of solar forcing on late Holocene North Pacific climate. The increased frequency of El Niño conditions during the LIA relative to the MCA is consistent with the modeled "ocean thermostat" mechanism whereby weak solar irradiance during the LIA promotes El Niño-like conditions, and strong MCA solar irradiance promotes La Niña-like conditions by modifying the east-west SST gradient in the tropical Pacific. We will also discuss the consistency of these paleoproxy records with models invoking solar-induced changes in the north-south temperature gradient at the tropopause. In these model results, weaker solar irradiance causes cooling and weaker westerly winds in the stratosphere, inducing a tropospheric response that includes expansion of the polar cell, contraction of the Hadley cell, and enhanced meridional circulation.

  1. Significance of isolated hepatitis B core antibody in blood donors from São Paulo

    Directory of Open Access Journals (Sweden)

    ALMEIDA NETO Cesar de

    2001-01-01

    Full Text Available The clinical significance of isolated anti-HBc is still a challenge. To elucidate the real importance of this finding in our blood donors, an investigation algorithm was tested. One hundred and twelve isolated anti-HBc seropositive blood donors underwent clinical evaluation and retesting of HBV markers. Those who presented repeatedly reactive isolated anti-HBc, received a single dose of hepatitis B recombinant vaccine to verify anti-HBs early response. A HBV-DNA determination by PCR was done for those who did not test positive to anti-HBs after vaccine. The level of anti-HBc was recorded as a ratio of the sample-to-cut-off values (S:C ratio in 57 candidates at donation. Comparing true and false-positive anti-HBc results, the different S:C ratios of them were statistically significant and when less than 2, implying in a false-positive result probability over 80%. A high percent of false-positive results (16.07% was verified after anti-HBc retesting. HBV immunity was characterized in 49.11%, either by anti-HBs detection in retesting (15.18%, or after a single dose HBV vaccination (33.93%. HBV-DNA was negative in all tested donors. In conclusion, this algorithm was useful to clarify the meaning of isolated anti-HBc in most of our blood donors.

  2. Development and significance of a fetal electrocardiogram recorded by signal-averaged high-amplification electrocardiography.

    Science.gov (United States)

    Hayashi, Risa; Nakai, Kenji; Fukushima, Akimune; Itoh, Manabu; Sugiyama, Toru

    2009-03-01

    Although ultrasonic diagnostic imaging and fetal heart monitors have undergone great technological improvements, the development and use of fetal electrocardiograms to evaluate fetal arrhythmias and autonomic nervous activity have not been fully established. We verified the clinical significance of the novel signal-averaged vector-projected high amplification ECG (SAVP-ECG) method in fetuses from 48 gravidas at 32-41 weeks of gestation and in 34 neonates. SAVP-ECGs from fetuses and newborns were recorded using a modified XYZ-leads system. Once noise and maternal QRS waves were removed, the P, QRS, and T wave intervals were measured from the signal-averaged fetal ECGs. We also compared fetal and neonatal heart rates (HRs), coefficients of variation of heart rate variability (CV) as a parasympathetic nervous activity, and the ratio of low to high frequency (LF/HF ratio) as a sympathetic nervous activity. The rate of detection of a fetal ECG by SAVP-ECG was 72.9%, and the fetal and neonatal QRS and QTc intervals were not significantly different. The neonatal CVs and LF/HF ratios were significantly increased compared with those in the fetus. In conclusion, we have developed a fetal ECG recording method using the SAVP-ECG system, which we used to evaluate autonomic nervous system development.

  3. Towards understanding North Pacific climate variabilty with instrumental and ice core records

    Science.gov (United States)

    Kelsey, Eric P.

    Reconstructing climate variability prior to the instrumental era is critical to advance our understanding of the Earth's climate system. Although many paleoclimate records from the North Atlantic basin have been studied, relatively few paleoclimate records have been recovered in the North Pacific leaving a gap in our knowledge concerning North Pacific climate variability. The Eclipse and Mount Logan Prospector-Russell ice cores are favorably located in the St. Elias Mountains, Yukon, Canada to document North Pacific climate variability over the late Holocene. Detailed analysis reveals a consistent relationship of surface air temperature (SAT) anomalies associated with extreme Arctic Oscillation (AO) and Pacific-North America (PNA) index values, and a consistent relationship of North Pacific sea level pressure (SLP) anomalies associated with extreme Mt. Logan annual [Na+] and Eclipse cold season accumulation values. Spatial SAT anomaly patterns are most consistent for AO and PNA index values ≥1.5 and ≤-1.5 during the period 1872-2010. The highest and lowest ˜10% of Eclipse warm and cold season stable isotopes are associated with distinct atmospheric circulation patterns. The most-fractionated isotope values occur with a weaker Aleutian Low, and the least-fractionated isotope values occur with an amplification of the Aleutian Low and northwestern North American ridge. The assumption of stationarity between ice core records and sea-level pressure was tested for the Eclipse cold season accumulation and Mt. Logan annual sodium concentration records for 1872-2001. A stationary relationship was found for ≥95% of years when Mt. Logan sodium concentrations were ≤1.32 microg/L, with positive SLP anomalies in the eastern North Pacific. This high frequency supports the use of low sodium values at Mt. Logan for a reconstruction of SLP prior to 1872. Negative SLP anomalies in the North Pacific occurred for extreme high sodium concentration years and positive SLP

  4. Dasuopu ice core record of atmospheric methane over the past 2000 years

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The concentrations of CH4 in the atmosphere over the past 2000 years have been deduced by extracting and analyzing the air in bubbles embedded in the Dasuopu ice core, Qinghai-Tibetan Plateau. Upon analyzing 57 ice core samples we found that the concentration of CH4 200 years ago and earlier was 0.85 m mol·mol-1 or about 40% of present atmospheric CH4 levels over Qinghai-Tibetan Plateau. A rapid and significant increase of atmospheric CH4 started about 200-250 a ago. For a given age before 19th century, the Dasuopu CH4 concentrations were about 15%-20% higher than those in Antarctic and Greenland references. It was also found that the Dasuopu CH4 concentrations changed more frequently, and its fluctuations could reflect the temperature change sensitively.

  5. Fidelity of Stable Oxygen Isotope Ratios as Environmental Recorders Using Multiple Coral Cores From Coastal Kenya

    Science.gov (United States)

    Naish, T.; Carter, B.; Abbott, S.; Field, B.; Zhu, H.; Wilson, G.; Alloway, B.; Edwards, S.; Pillans, B.; Barker, A.; Niessen, F.; Maslen, G.; Beu, A.; Fleitmann, D.; Dunbar, R. B.; Mucciarone, D. A.

    2004-12-01

    Climate variability in the western equatorial Indian Ocean reflects the combined influence of seasonally changing sea surface temperature (SST), ocean currents, and monsoon circulation, as well as inter-annual to -decadal variability associated with ENSO in the Pacific. However, the Indian Ocean also exhibits variability that appears unrelated to ENSO in the Pacific. The nature of interactions between air-sea variability in the Indian and Pacific oceans is not yet fully resolved, in part because of the lack of long-term, high-resolution SST records from key localities in the Indian Ocean. Such records are now being obtained using oxygen isotope profiles measured on corals from East Africa, Indonesia, Australia, and Indian Oceania (Maldives, Seychelles), with the longest coral-based time series from Malindi, Kenya, covering the last 300 years at near-monthly resolution. The value of these developing coral records depends on the fidelity with which they record regional climate variability. In order to assess the fidelity of oxygen isotope ratios (\\delta18O) in Indian Ocean corals as a proxy for sea surface temperature, we have generated stable isotopic time series from multiple Porites lutea coral heads collected along the coast of Kenya. Coral-based isotopic paleoclimatology is labor and time-intensive so detailed analyses using multiple coral heads from different sites within a region are extremely rare. Most published records are produced from a single coral head, yet questions have been raised about the accuracy of such records. To address such concerns, near-monthly resolution isotopic profiles, spanning 10 to 50 years prior to 1997, were measured on a total of 8 cores from five sites along a north-south transect between 2° and 4° S (Kiwayu: 2° 2'S, 41° 2'E, Malindi: 3° 14'S, 40° 8'E, Watamu: 3° 23'S, 39° 52'E, Mombasa: 3° 59'S, 39° 5'E, and Kisite: 4° 43'S, 39° 23'E. Correlations among individual \\delta18O time series (r values range from 0.65 to

  6. A 290-year Record of Atmospheric Circulation over the North Pacific from A Mt. Logan Ice Core, Yukon Territory

    Science.gov (United States)

    Kang, S.; Mayewski, P. A.; Yan, Y.

    2002-12-01

    Calibrations between sodium (Na) concentrations from a Mt. Logan ice core and sea level pressure (SLP) series show that Na concentrations are closely correlated with the autumn-time (September-October-November) Aleutian Low (AleuLow) and the summer-time (June-July-August) North Pacific High (NPaciHi). Both the deepening of the AleuLow and intensification of the NPaciHi strengthen the transport of sea-salt aerosols from the North Pacific to the Mt. Logan region. Mt. Logan Na records are used to develop a 292-year (1688-1979) reconstruction of the AleuLow and NPaciHi. Examination of the proxy records reveals a dramatic intensification of atmospheric circulation over the North Pacific region since the 20th century. Mean SLP of the AleuLow is about 1 mb lower, and 0.6 mb higher for the NPaciHi during the 20th century. The strongest deepening of the AleuLow was accompanied by a strengthening of the NPaciHi in the 1950s. Evolutionary spectral analysis of the proxy records shows significant periodicity consistent with a bidecadal oscillation (20-30 years) of North Pacific atmosphere-ocean circulation as well as the solar Gleissberg cycle (80-90 years).

  7. Multi-proxy fingerprint of Heinrich event 4 in Greenland ice core records

    Directory of Open Access Journals (Sweden)

    M. Guillevic

    2014-03-01

    Full Text Available Glacial climate was characterised by two types of abrupt events. Greenland ice cores record Dansgaard–Oeschger events, marked by abrupt warming in-between cold, stadial phases. Six of these stadials coincide with major Heinrich events (HE, identified from ice-rafted debris (IRD and large excursions in carbon and oxygen stable isotopic ratios in North Atlantic deep sea sediments, documenting major ice sheet collapse events. This finding has led to the paradigm that glacial cold events are induced by the response of the Atlantic Meridional Overturning Circulation to such massive freshwater inputs, supported by sensitivity studies conducted with climate models of various complexities. This mechanism could however never be confirmed or infirmed because the exact timing of Heinrich events and associated low latitude hydrological cycle changes with respect to Greenland stadials has so far remained elusive. Here, we provide the first multi-proxy fingerprint of H4 within Stadial 9 in Greenland ice cores through ice and air proxies of low latitude climate and water cycle changes. Our new dataset demonstrates that Stadial 9 consists of three phases, characterised first by Greenland cooling during 550 ± 60 years (as shown by markers of Greenland temperature δ18O and δ15N, followed by the fingerprint of Heinrich Event 4 as identified from several proxy records (abrupt decrease in 17O excess and Greenland methane sulfonic acid (MSA, increase in CO2 and methane mixing ratio, heavier δ D-CH4 and δ18Oatm, lasting 740 ± 60 years, itself ending approximately 390 ± 50 years prior to abrupt Greenland warming. Preliminary investigations on GS-13 encompassing H5, based on the ice core proxies δ18O, MSA, δ18Oatm, CH4 and CO2 data also reveal a 3 phase structure, as well as the same sequence of events. The decoupling between stable cold Greenland temperature and low latitude HE imprints provides new targets for benchmarking climate model simulations and

  8. The sunspot cycle recorded in the thermoluminescence profile of the GT89/3 Ionian sea core

    Energy Technology Data Exchange (ETDEWEB)

    Cini Castagnoli, G.; Bonino, G.; Taricco, C. [Turin Univ. (Italy). Ist. di Fisica Generale]|[CNR, Turin (Italy). Ist. di Cosmogeofisica

    1997-11-01

    The authors measured the thermoluminescence (TL) depth of the GT89/3 shallow-water Ionian sea core. This profile has been transformed into a time series using the accurate sedimentation rate previously determined by radiometric and tephroanalysis methods. The TL measurements were performed in samples of equal thickness of 2 mm, corresponding to a time interval of 3.096 y. The TL time series spans {approx} 1800 y. The DFT power spectral densities in the decadal periodicity range of this TL series show significant periodicities at 10.7, 11.3 and 12 y closely similar to the periodicities present in the sunspot number series. These results confirm that the TL signal in recent sea sediments faithfully records the solar variability, as we previously proposed.

  9. SOCIAL AND LEGAL SIGNIFICANCE OF DIGITAL MEANS FOR RECORDING INFORMATION IN CRIMINAL PROCEEDINGS

    Directory of Open Access Journals (Sweden)

    Anna Aleksandrovna Petrikina

    2015-01-01

    Full Text Available The article is devoted to the actual topic – social and legal significance of digital media for recording information in criminal proceedings. Modern society is impossible without digital media. There are strong debates in mass media and scientific community regarding the benefits and dangers of this method of fixation. The majority of methods using photo- and videoshooting in legal proceedings in Russia is stipulated in legislation and applied in investigative practices, expertise and operational investigations. The use of technical means of fixation during the investigative actions serves as evidence. It is recognized as admissible in case of its compliance with the statutory procedures of investigation actions for fixation of which are used technical means. In recent times, the dynamic development of this sector is facing problems of legal regulation.

  10. Roosevelt Island Climate Evolution Project (RICE): A 65 Kyr ice core record of black carbon aerosol deposition to the Ross Ice Shelf, West Antarctica.

    Science.gov (United States)

    Edwards, Ross; Bertler, Nancy; Tuohy, Andrea; Neff, Peter; Proemse, Bernedette; Feiteng, Wang; Goodwin, Ian; Hogan, Chad

    2015-04-01

    Emitted by fires, black carbon aerosols (rBC) perturb the atmosphere's physical and chemical properties and are climatically active. Sedimentary charcoal and other paleo-fire records suggest that rBC emissions have varied significantly in the past due to human activity and climate variability. However, few paleo rBC records exist to constrain reconstructions of the past rBC atmospheric distribution and its climate interaction. As part of the international Roosevelt Island Climate Evolution (RICE) project, we have developed an Antarctic rBC ice core record spanning the past ~65 Kyr. The RICE deep ice core was drilled from the Roosevelt Island ice dome in West Antarctica from 2011 to 2013. The high depth resolution (~ 1 cm) record was developed using a single particle intracavity laser-induced incandescence soot photometer (SP2) coupled to an ice core melter system. The rBC record displays sub-annual variability consistent with both austral dry-season and summer biomass burning. The record exhibits significant decadal to millennial-scale variability consistent with known changes in climate. Glacial rBC concentrations were much lower than Holocene concentrations with the exception of several periods of abrupt increases in rBC. The transition from glacial to interglacial rBC concentrations occurred over a much longer time relative to other ice core climate proxies such as water isotopes and suggests . The protracted increase in rBC during the transition may reflected Southern hemisphere ecosystem / fire regime changes in response to hydroclimate and human activity.

  11. Memory-bit selection and recording by rotating fields in vortex-core cross-point architecture

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Y. -S.; Jung, H.; Lee, K. -S.; Fischer, P.; Kim, S. -K.

    2010-10-21

    In one of our earlier studies [Appl. Phys. Lett. 92, 022509 (2008)], we proposed a concept of robust information storage, recording and readout, which can be implementaed in nonvolatile magnetic random-access memories and is based on the energetically degenerated twofold ground states of vortex-core magnetizations. In the present study, we experimentally demonstrate reliable memory-bit selection and information recording in vortex-core cross-point architecture, specifically using a two-by-two vortex-state disk array. In order to efficiently switch a vortex core positioned at the intersection of crossed electrodes, two orthogonal addressing electrodes are selected, and then two Gaussian pulse currents of optimal pulse width and time delay are applied. Such tailored pulse-type rotating magnetic fields which occurs only at the selected intersection is prerequisite for a reliable memory-bit selection and low-power-consumption recording of information in the existing cross-point architecture.

  12. Determination of linear alkylbenzenesulfonates in modern sediments from core Zhu-9 and its significance

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    High performance liquid chromatography (HPLC) has the advantages of rapid analysis and high sensitivity. In the present study a suitable analytical condition has been established for HPLC, and the LAS in modern sediments from core Zhu-9 at the Pearl River mouth has been determined by HPLC. The concentrations of C12-LAS homologues are the highest. The sedimentation flux of C12-LAS was correlated with the average flow of the Xijiang and Beijiangrivers: the higher the flow rate, the larger the C12-LAS sedimentation flux. This shows that the more rapidly the river flows, the shorter the LAS will stay in freshwater, the less the extent of biodegradation, the larger the C12-LAS sedimentation flux in the core Zhu-9.

  13. Significance of Quaternary and Experimental Fluvial Systems to Interpretation of the Stratigraphic Record

    Science.gov (United States)

    Blum, M. D.; Martin, J. M.

    2012-12-01

    Studies of Quaternary and experimental fluvial systems provide significant insight for interpretation of fluvial deposits in the stratigraphic record, ranging from measurement of processes and relevant scales of key architectural elements, to process-based understanding of fluvial systems in sequence stratigraphic models. One key advantage for Quaternary and experimental systems is they commonly provide the ability to test, in a classical verification or falsification sense, interpretations, models and their alternatives that were developed from the stratigraphic record alone. First, scaling relationships developed from Quaternary fluvial deposits can be utilized to constrain interpretations of ancient strata, as well as predict the scale of channel fills, channel-belt sand bodies, and incised valleys. Scaling relationships are defined by power laws, with absolute dimensions that scale to drainage area, water flux, and sediment flux. Width-to-thickness ratios for channel fills range from 10-20:1, whereas channel-belt sand bodies upstream from backwater effects commonly range from 70-300:1, and 20-40:1within the backwater zone, where channel migration is limited. Quaternary incised valleys range from 25-150 m in thickness, and ~5-100 km in width, with width-to-thickness ratios of ~500-800. Scales of Quaternary channel fills and channel-belt sand bodies overlap are consistent with compilations from the ancient record. However, even the smallest Quaternary incised valleys reside in the uppermost part of the domain of published ancient valleys, with ancient examples overlapping significantly with modern channel fills and channel belts. We suggest that many ancient examples have been overinterpreted because of a lack of objective criteria for differentiating channel fills, channel belts, and incised valleys. Second, incised valleys have long played a key role in sequence-stratigraphic interpretations. For incised valleys in the stratigraphic record, either in outcrop or

  14. Climatic and environmental changes over the last millennium recorded in the Malan ice core from the northern Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG Ninglian; YAO Tandong; PU Jianchen; ZHANG Yongliang; SUN Weizhen

    2006-01-01

    In this paper, climatic and environmental changes were reconstructed since 1129A.D.based on the Malan ice core from Hol Xil, the northern Tibetan Plateau. The record of δ18O in the Malan ice core indicated that the warm-season air temperature variations displayed a general increase trend, the 20th-century warming was within the range of natural climate variability, and the warmest century was the 17th century while the warmest decade was the 1610s, over the entire study period. The "Medieval Warm Epoch" and "Little Ice Age" were also reflected by the ice core record.The dust ratio in the Malan ice core is a good proxy for dust event frequency. The 870-year record of the dust ratio showed that dust events occurred much frequently in the 19th century. Comparing the variations of δ18O and the dust ratio, it is found that there was a strong negative correlation between them on the time scales of 101 - 102 years. By analyses of all the climatic records of ice cores and tree rings from the northern Tibetan Plateau, it was revealed that dust events were more frequent in the cold and dry periods than in the warm and wet periods.

  15. Characteristics of Dust Deposition at High Elevation Sites in Caucasus Over the Past 190 years Recorded in Ice Cores.

    Science.gov (United States)

    Kutuzov, Stanislav; Ginot, Patrick; Mikhaenko, Vladimir; Krupskaya, Victoria; Legrand, Michel; Preunkert, Suzanne; Polukhov, Alexey; Khairedinova, Alexandra

    2017-04-01

    The nature and extent of both radiative and geochemical impacts of mineral dust on snow pack and glaciers depend on physical and chemical properties of dust particles and its deposition rates. Ice cores can provide information about amount of dust particles in the atmosphere and its characteristic and also give insights on strengths of the dust sources and its changes in the past. A series of shallow ice cores have been obtained in Caucasus mountains, Russia in 2004 - 2015. A 182 meter ice core has been recovered at the Western Plateau of Mt. Elbrus (5115 m a.s.l.) in 2009. The ice cores have been dated using stable isotopes, NH4+ and succinic acid data with the seasonal resolution. Samples were analysed for chemistry, concentrations of dust and black carbon, and particle size distributions. Dust mineralogy was assessed by XRD. Individual dust particles were analysed using SEM. Dust particle number concentration was measured using the Markus Klotz GmbH (Abakus) implemented into the CFA system. Abakus data were calibrated with Coulter Counter multisizer 4. Back trajectory cluster analysis was used to assess main dust source areas. It was shown that Caucasus region experiencing influx of mineral dust from the Sahara and deserts of the Middle East. Mineralogy of dust particles of desert origin was significantly different from the local debris material and contained large proportion of calcite and clay minerals (kaolinite, illite, palygorskite) associated with material of desert origin. Annual dust flux in the Caucasus Mountains was estimated as 300 µg/cm2 a-1. Particle size distribution depends on individual characteristics of dust deposition event and also on the elevation of the drilling site. The contribution of desert dust deposition was estimated as 35-40 % of the total dust flux. Average annual Ca2+ concentration over the period from 1824 to 2013 was of 150 ppb while some of the strong dust deposition events led to the Ca2+ concentrations reaching 4400 ppb. An

  16. Complete Au@ZnO core-shell nanoparticles with enhanced plasmonic absorption enabling significantly improved photocatalysis.

    Science.gov (United States)

    Sun, Yiqiang; Sun, Yugang; Zhang, Tao; Chen, Guozhu; Zhang, Fengshou; Liu, Dilong; Cai, Weiping; Li, Yue; Yang, Xianfeng; Li, Cuncheng

    2016-05-19

    Nanostructured ZnO exhibits high chemical stability and unique optical properties, representing a promising candidate among photocatalysts in the field of environmental remediation and solar energy conversion. However, ZnO only absorbs the UV light, which accounts for less than 5% of total solar irradiation, significantly limiting its applications. In this article, we report a facile and efficient approach to overcome the poor wettability between ZnO and Au by carefully modulating the surface charge density on Au nanoparticles (NPs), enabling rapid synthesis of Au@ZnO core-shell NPs at room temperature. The resulting Au@ZnO core-shell NPs exhibit a significantly enhanced plasmonic absorption in the visible range due to the Au NP cores. They also show a significantly improved photocatalytic performance in comparison with their single-component counterparts, i.e., the Au NPs and ZnO NPs. Moreover, the high catalytic activity of the as-synthesized Au@ZnO core-shell NPs can be maintained even after many cycles of photocatalytic reaction. Our results shed light on the fact that the Au@ZnO core-shell NPs represent a promising class of candidates for applications in plasmonics, surface-enhanced spectroscopy, light harvest devices, solar energy conversion, and degradation of organic pollutants.

  17. Significant Atmospheric Boundary Layer Change Observed above an Agulhas Current Warm Cored Eddy

    Directory of Open Access Journals (Sweden)

    C. Messager

    2016-01-01

    Full Text Available The air-sea impact of a warm cored eddy ejected from the Agulhas Retroflection region south of Africa was assessed through both ocean and atmospheric profiling measurements during the austral summer. The presence of the eddy causes dramatic atmospheric boundary layer deepening, exceeding what was measured previously over such a feature in the region. This deepening seems mainly due to the turbulent heat flux anomaly above the warm eddy inducing extensive deep and persistent changes in the atmospheric boundary layer thermodynamics. The loss of heat by turbulent processes suggests that this kind of oceanic feature is an important and persistent source of heat for the atmosphere.

  18. Paleoenvironmental informa-tion recorded by pollen in B-3GC gravity core in Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on pollen records in B-3GC gravity core, environmental change since 9500 aBP of Okinawa Trough and its adjacent islands was derived. The result showed that the most time during this period was in a warm temperate climate except in middle Holocene (6800-4400 aBP) that was under subtropical climate control. During 9500-8300 aBP and 3100-2000 aBP periods, it appeared colder and drier than the rest time. The original area of pollen sources surrounding Okinawa Trough was covered by evergreen and deciduous broadleaf forest alternatively with mixed broad-leaf-conifer forest distributed in high mountainous areas. Usually, these three kinds of forests existed at the same time with difference in altitude. Pollen from subtropical and tropical plants increased obviously in about 5000-6000 aBP, reflecting a great lifting of vegetation zone and expansion of evergreen broad-leaf forest in the study area. However, there was a slight descending of plant zone and shrinking of evergreen broadleaf forest during 9500-8300 aBP and 3000-2000 aBP. During the remaining periods vegetation zone was higher than the present but in a limited range.

  19. Bellingshausen Sea ice extent recorded in an Antarctic Peninsula ice core

    Science.gov (United States)

    Porter, Stacy E.; Parkinson, Claire L.; Mosley-Thompson, Ellen

    2016-12-01

    Annual net accumulation (An) from the Bruce Plateau (BP) ice core retrieved from the Antarctic Peninsula exhibits a notable relationship with sea ice extent (SIE) in the Bellingshausen Sea. Over the satellite era, both BP An and Bellingshausen SIE are influenced by large-scale climatic factors such as the Amundsen Sea Low, Southern Annular Mode, and Southern Oscillation. In addition to the direct response of BP An to Bellingshausen SIE (e.g., more open water as a moisture source), these large-scale climate phenomena also link the BP and the Bellingshausen Sea indirectly such that they exhibit similar responses (e.g., northerly wind anomalies advect warm, moist air to the Antarctic Peninsula and neighboring Bellingshausen Sea, which reduces SIE and increases An). Comparison with a time series of fast ice at South Orkney Islands reveals a relationship between BP An and sea ice in the northern Weddell Sea that is relatively consistent over the twentieth century, except when it is modulated by atmospheric wave patterns described by the Trans-Polar Index. The trend of increasing accumulation on the Bruce Plateau since 1970 agrees with other climate records and reconstructions in the region and suggests that the current rate of sea ice loss in the Bellingshausen Sea is unrivaled in the twentieth century.

  20. An Andean ice-core record of a Middle Holocene mega-drought in North Africa and Asia

    Science.gov (United States)

    Davis, Mary E.; Thompson, Lonnie G.

    An ice core from the Nevado Huascarán col in the Cordillera Blanca of northern Peru contains high-resolution time series of dust concentrations and size distributions since the end of the last glacial stage. A large dust peak, dated ˜4500 years ago, is contemporaneous with a widespread and prolonged drought that apparently extended from North Africa to eastern China, evidence of which occurs in historical, archeological and paleoclimatic records. This event may have been associated with several centuries of weak Asian/Indian/African monsoons, possibly linked with a protracted cooling in the North Atlantic. During the second half of the 20th century, high austral-summer dust concentrations in the Huascarán record are significantly correlated with atmospheric conditions, such as sea-level pressure and zonal wind velocities that are consistent with El Niño-Southern Oscillation (ENSO) and positive North Atlantic Oscillation (NAO) indices, and with aridity in North Africa, southwest Asia and the Middle East. Therefore, the dominant submicron fraction of the dust may have been transported by more intense northeasterly trade winds from the African dry regions across the tropical Atlantic during a period of frequent and/or intense ENSO activity. The proposed ENSO conditions that may have been linked with drought in the monsoon region may also have contributed to aridity in tropical South America, including the Cordillera Blanca.

  1. A 1,000-year ice core record of interannual to multidecadal variations in atmospheric circulation over the North Atlantic

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Hubertus; Mieding, Birgit [Alfred Wegener Institute for Polar and Marine Research, Bremerhaven (Germany)

    2005-07-01

    Interannual to multidecadal modes in ocean/atmosphere dynamics in the North Atlantic region have been identified using sea salt aerosol proxy records from northern Greenland ice cores over the last 1,000 years. Sea salt concentrations show a consistent relationship with anomalies in the meridional pressure gradient over the North Atlantic region over all considered time scales. These pressure anomalies are connected to shifts in storm tracks, leading to lower pressure and higher storm activity, hence, higher sea salt export over the Greenland ice sheet. Two modes of long-term variability with a period of 10.4 years and 62 years could be identified. The latter is connected to long-term changes in sea surface temperature (SST) as documented by a high correlation of North Atlantic SST with our sea salt record over the last 150 years. Long-term reconstruction of these modes shows that the 10.4-year cycle has been a phenomenon persistent over the last millennium while the 62-year cycle has been mainly active after 1700. Accordingly, the longer-term persistence of this multidecadal variability in sea salt points also to significant variations in SST over the last 300 years. (orig.)

  2. Possible Recording of the Hilina Pali Excursion in Cored Tyrrhenian Sea Sediment

    Science.gov (United States)

    Iorio, Marina; Liddicoat, Joseph; Sagnotti, Leonardo; Incoronato, Alberto; de Anteriis, Giovanni; Insinga, Donatella; Angelino, Antimo

    2013-04-01

    First encountered in marine sediment cored from the Gulf of Mexico (19.5˚ N, 267.0˚ E)(Clark and Kennett, 1973), the Hilina Pali Excursion (HPE) is named for a locality in Hawaii (19.5˚ N, 205.0˚ E) where inclination of about negative 40˚ is documented in cored basalt (Teanby et al., 2002). Prior to naming the excursion, Coe et al. (1978) also found shallow inclination in basalt from Kilauea Volcano (19.2˚ N, 204.7˚ E) that is dated at about 18,000 yrs B.P. (uncorrected Carbon-14, Rubin and Berthold, 1961) - the age now assigned to the HPE - and was erupted when the field intensity was reduced to nearly half the present intensity. More recently, the HPE was located at Changbaishan Volcano in northeastern China (40.2˚ N, 128.0˚ E) where the age is established by Ar40/Ar39 dates (Singer et al., 2011). In exposed lake sediments in the Mono Basin, CA (38.0˚ N, 240.8˚ E), shallow positive inclination at about 18,000 yrs B.P. might also be the HPE. In the Mono Basin, normalized (NRM/ARM) intensity is reduced at that time (Zimmerman et al., 2006), and the Virtual Geomagnetic Poles (VGPs) during the reduced intensity form a clockwise trending loop when followed from old to young that descends to 53.8˚ N, 22.7˚ E (n = 6, Alpha-95 = 2.3˚) and is centered at about 50˚ N, 30˚ E (Coe and Liddicoat, 2012). There is a possible excursion of the palaeomagnetic field recorded in marine sediment at a locality in the Tyrrhenian Sea about 25 km south of Ischia (40.5˚ N, 13.7˚ E). The excursion is in sediment from two core segments that span about 22,000-18,000 yrs B.P. (de Alteriis et al., 2010) and occurs as reduced positive inclination (about 50˚) at about 20,000 yrs B.P. that increases to about 80˚ at about 18,000 yrs B.P. when declination changes from west to east. This pattern of field behaviour is similar to the behaviour of the possible HPE in the Mono Basin (Coe and Liddicoat, 2012) and in sediment cored from Lac du Bouchet, FR (44.9˚ N, 3.8˚ E) that is

  3. δ18O record and temperature change over the past 100 years in ice cores on the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    YAO; Tandong; GUO; Xuejun; Lonnie; Thompson; DUAN; Keqin; WANG; Ninglian; PU; Jianchen; XU; Baiqing; YANG; Xiaoxin; SUN; Weizhen

    2006-01-01

    The 213 m ice core from the Puruogangri Ice Field on the Tibetan Plateau facilitates the study of the regional temperature changes with its δ18O record of the past 100 years. Here we combine information from this core with that from the Dasuopu ice core (from the southern Tibetan Plateau), the Guliya ice core (from the northwestern Plateau) and the Dunde ice core (from the northeastern Plateau) to learn about the regional differences in temperature change across the Tibetan Plateau. The δ18O changes vary with region on the Plateau, the variations being especially large between South and North and between East and West. Moreover, these four ice cores present increasing δ18O trends, indicating warming on the Tibetan Plateau over the past 100 years. A comparative study of Northern Hemisphere (NH) temperature changes, the δ18O-reflected temperature changes on the Plateau, and available meteorological records show consistent trends in overall warming during the past 100 years.

  4. Climatic changes on orbital and sub-orbital time scale recorded by the Guliya ice core in Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    姚檀栋; 徐柏青; 蒲健辰

    2001-01-01

    Based on ice core records in the Tibetan Plateau and Greenland, the features and possible causes of climatic changes on orbital and sub-orbital time scale were discussed. Orbital time scale climatic change recorded in ice core from the Tibetan Plateau is typically ahead of that from polar regions, which indicates that climatic change in the Tibetan Plateau might be earlier than polar regions. The solar radiation change is a major factor that dominates the climatic change on orbital time scale. However, climatic events on sub-orbital time scale occurred later in the Tibetan Plateau than in the Arctic Region, indicating a different mechanism. For example, the Younger Dryas and Heinrich events took place earlier in Greenland ice core record than in Guliya ice core record. It is reasonable to propose the hypothesis that these climatic events were affected possibly by the Laurentide Ice Sheet. Therefore, ice sheet is critically important to climatic change on sub-orbital time scale in some ice ages.

  5. Distal tephra record for the last ca 105,000 years from core PRAD 1-2 in the central Adriatic Sea: implications for marine tephrostratigraphy

    Science.gov (United States)

    Bourne, A. J.; Lowe, J. J.; Trincardi, F.; Asioli, A.; Blockley, S. P. E.; Wulf, S.; Matthews, I. P.; Piva, A.; Vigliotti, L.

    2010-11-01

    Core PRAD 1-2, located on the western flank of the Mid-Adriatic Deep, contains a continuous sediment record extending back to upper MIS-11. The upper part of the record which spans the mid Holocene to MIS 5-4 (the last ca 105,000 years) has been investigated for tephra content. A total of 25 discrete tephra layers were discovered, only one of which was visible in the core sequence. The other 24 are not visible to the naked eye, nor were the majority detected by routine down-core scanning methods. A total of 625 geochemical measurements obtained from individual glass shards using WDS-EPMA enabled 21 of the 25 tephras to be assigned to known volcanic events emanating from the Campanian Province (Campi Flegrei, Somma-Vesuvius and Ischia Island). The results provide an independent basis for establishing an age-depth profile for the upper part of the PRAD 1-2 record. This study demonstrates that the number of non-visible tephra layers can significantly exceed the number of visible layers in some deep marine sequences. Routine testing for the presence of non-visible tephra layers can therefore prove rewarding, leading to the detection of additional isochrons for dating and correlating marine sequences, and for their synchronisation with terrestrial records.

  6. Where might we find evidence of a Last Interglacial West Antarctic Ice Sheet collapse in Antarctic ice core records?

    Science.gov (United States)

    Bradley, S. L.; Siddall, M.; Milne, G. A.; Masson-Delmotte, V.; Wolff, E.

    2012-05-01

    Abundant indirect evidence suggests that the West Antarctic Ice Sheet (WAIS) reduced in size during the Last Interglacial (LIG) compared to the Holocene. This study explores this possibility by comparing, for the first time, ice core stable isotope records for the LIG with output from a glacio-isostatic adjustment (GIA) model. The results show that ice core records from East Antarctica are remarkably insensitive to vertical movement of the solid land motion driven by a simulated hypothetical collapse of the WAIS. However, new and so far unexplored sites are identified which are sensitive to the isostatic signal associated with WAIS collapse and so ice core proxy data from these sites would be effective in testing this hypothesis further.

  7. Lead isotope ratios in six lake sediment cores from Japan Archipelago: Historical record of trans-boundary pollution sources

    Energy Technology Data Exchange (ETDEWEB)

    Hosono, Takahiro, E-mail: hosono@kumamoto-u.ac.jp [Priority Organization for Innovation and Excellence, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Alvarez, Kelly [Priority Organization for Innovation and Excellence, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Kuwae, Michinobu [Senior Research Fellow Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 (Japan)

    2016-07-15

    Sediment cores from six lakes situated from north to south on the Japanese Archipelago were collected during 2009–2010 to investigate the hypothesis that deposition of lead (Pb) was coming from East Asia (including China, South Korea and eastern part of Russia). Accumulation rates and ages of the lake sediment were estimated by the {sup 210}Pb constant rate of supply model and {sup 137}Cs inputs to reconstruct the historical trends of Pb accumulation. Cores from four lakes located in the north and central Japan, showed clear evidence of Pb pollution with a change in the {sup 206}Pb/{sup 207}Pb and {sup 208}Pb/{sup 207}Pb ratios in the recent sediment as compared to the deeper sediment. Among the six studied lakes, significant inputs of anthropogenic lead emissions were observed at Lake Mikazuki (north Hokkaido in north Japan), Lake Chokai (north of Honshu), and Lake Mikuriga (central part of Honshu). Pb isotopic comparison of collected core sediment and previously reported data for wet precipitation and aerosols from different Asian regions indicate that, before 1900, Pb accumulated in these three lakes was not affected by trans-boundary sources. Lake Mikazuki started to receive Pb emissions from Russia in early 1900s, and during the last two decades, this lake has been affected by trans-boundary Pb pollution from northern China. Lake Chokai has received Pb pollutant from northern China since early 1900s until 2009, whereas for the Lake Mikuriga the major Pb contaminant was transported from southern China during the past 100 years. The results of our study demonstrate that Japan Archipelago has received trans-boundary Pb emissions from different parts of East Asian region depending on location, and the major source region has changed historically. - Highlights: • Historical trend of Pb pollution was recorded in six Japanese Lakes. • Pb concentration and Pb isotope ratios were determined for sediment cores. • High [Pb] and less radiogenic Pb isotope ratios

  8. Anthropogenic-enhanced erosion following the Neolithic Revolution in the Southern Levant: Records from the Dead Sea deep drilling core

    Science.gov (United States)

    Lu, Yin; Waldmann, Nicolas; Nadel, Dani; Marco, Shmuel

    2017-04-01

    In addition to tectonics and climatic changes, humans have exerted a significant impact on surface erosion over timescales ranging from years to centuries. However, such kind of impact over millennial timescales remains unsubstantiated. The Dead Sea drainage basin offers a rare combination of well-documented substantial climate change, intense tectonics and abundant archaeological evidence for past human activity in the Southern Levant. It serves as a natural laboratory for understanding how sedimentation rates in a deep basin are related to climate change, tectonics, and anthropogenic impacts on the landscape. Here we show how basin-wide erosion rates are recorded by thicknesses of rhythmic detritus laminae and clastic sediment accumulation rates in a long core retrieved by the Dead Sea Deep Drilling Project in the Dead Sea depocenter. During the last 11.5 kyr the average detrital accumulation rate is 3-4 times that during the last two glacial cycles (MIS 7c-2), and the average thickness of detritus laminae in the last 11.6 kyr is 4.5 times that between 21.7 and 11.6 ka, implying an increased erosion rate on the surrounding slopes during the Holocene. We estimate that this intensified erosion is incompatible with tectonic and climatic regimes during the corresponding time interval and further propose a close association with the Neolithic Revolution in the Levant (beginning at 11.5 ka). We thus suggest that human impact on the landscape was the primary driver causing the intensified erosion and that the Dead Sea sedimentary record serves as a reliable recorder of this impact since the Neolithic Revolution.

  9. Variations in dust event frequency over the past century reflected by ice-core and lacustrine records in north China

    Institute of Scientific and Technical Information of China (English)

    WANG NingLian; YAO TanDong; YANG XiangDong; SHEN Ji; WANG Yong

    2007-01-01

    In this paper, we analyzed the variations of dust proxies in the Dunde, Malan and Chongce ice cores from the northern Tibetan Plateau and the Hongjiannao lacustrine sediment core from north Shaanxi Province, and found that they all showed a general decrease trend over the past century. Owing to the fact that all these ice cores and lacustrine core were retrieved from the margins and/or the leeward sides of the major areas of dust events in north China, their records could suggest that the dust event frequency in north China declined over the study period. This decrease trend might be attributed to increasing precipitation and weakening westerly. However, human activities have made the areal extent of desertification expand acceleratingly in north China. This status could make it possible that dust events would occur on a large spatial scale under the future climate change, which would be a big environmental issue we shall face.

  10. A stratigraphic framework for naming and robust correlation of abrupt climatic changes during the last glacial period based on three synchronized Greenland ice core records

    Science.gov (United States)

    Rasmussen, Sune O.

    2014-05-01

    Due to their outstanding resolution and well-constrained chronologies, Greenland ice core records have long been used as a master record of past climatic changes during the last interglacial-glacial cycle in the North Atlantic region. As part of the INTIMATE (INtegration of Ice-core, MArine and TErrestrial records) project, protocols have been proposed to ensure consistent and robust correlation between different records of past climate. A key element of these protocols has been the formal definition of numbered Greenland Stadials (GS) and Greenland Interstadials (GI) within the past glacial period as the Greenland expressions of the characteristic Dansgaard-Oeschger events that represent cold and warm phases of the North Atlantic region, respectively. Using a recent synchronization of the NGRIP, GRIP, and GISP2 ice cores that allows the parallel analysis of all three records on a common time scale, we here present an extension of the GS/GI stratigraphic template to the entire glacial period. This is based on a combination of isotope ratios (δ18O, reflecting mainly local temperature) and calcium concentrations (reflecting mainly atmospheric dust loading). In addition to the well-known sequence of Dansgaard-Oeschger events that were first defined and numbered in the ice core records more than two decades ago, a number of short-lived climatic oscillations have been identified in the three synchronized records. Some of these events have been observed in other studies, but we here propose a consistent scheme for discriminating and naming all the significant climatic events of the last glacial period that are represented in the Greenland ice cores. This is a key step aimed at promoting unambiguous comparison and correlation between different proxy records, as well as a more secure basis for investigating the dynamics and fundamental causes of these climatic perturbations. The work presented is under review for publication in Quaternary Science Reviews. Author team: S

  11. Complete Au@ZnO core-shell nanoparticles with enhanced plasmonic absorption enabling significantly improved photocatalysis

    Science.gov (United States)

    Sun, Yiqiang; Sun, Yugang; Zhang, Tao; Chen, Guozhu; Zhang, Fengshou; Liu, Dilong; Cai, Weiping; Li, Yue; Yang, Xianfeng; Li, Cuncheng

    2016-05-01

    Nanostructured ZnO exhibits high chemical stability and unique optical properties, representing a promising candidate among photocatalysts in the field of environmental remediation and solar energy conversion. However, ZnO only absorbs the UV light, which accounts for less than 5% of total solar irradiation, significantly limiting its applications. In this article, we report a facile and efficient approach to overcome the poor wettability between ZnO and Au by carefully modulating the surface charge density on Au nanoparticles (NPs), enabling rapid synthesis of Au@ZnO core-shell NPs at room temperature. The resulting Au@ZnO core-shell NPs exhibit a significantly enhanced plasmonic absorption in the visible range due to the Au NP cores. They also show a significantly improved photocatalytic performance in comparison with their single-component counterparts, i.e., the Au NPs and ZnO NPs. Moreover, the high catalytic activity of the as-synthesized Au@ZnO core-shell NPs can be maintained even after many cycles of photocatalytic reaction. Our results shed light on the fact that the Au@ZnO core-shell NPs represent a promising class of candidates for applications in plasmonics, surface-enhanced spectroscopy, light harvest devices, solar energy conversion, and degradation of organic pollutants.Nanostructured ZnO exhibits high chemical stability and unique optical properties, representing a promising candidate among photocatalysts in the field of environmental remediation and solar energy conversion. However, ZnO only absorbs the UV light, which accounts for less than 5% of total solar irradiation, significantly limiting its applications. In this article, we report a facile and efficient approach to overcome the poor wettability between ZnO and Au by carefully modulating the surface charge density on Au nanoparticles (NPs), enabling rapid synthesis of Au@ZnO core-shell NPs at room temperature. The resulting Au@ZnO core-shell NPs exhibit a significantly enhanced plasmonic

  12. Tephra in marine sediment cores offshore southern Iceland: A 68,000 year record of explosive volcanism

    Science.gov (United States)

    Bonanati, Christina; Wehrmann, Heidi; Portnyagin, Maxim; Hoernle, Kaj; Mirzaloo, Maryam; Nürnberg, Dirk

    2016-04-01

    Explosive volcanic eruptions on Iceland, even of intermediate magnitude have far-reaching impacts. Their far-distal deposits have been found up to Northern Continental Europe and Greenland. On Iceland, the harsh environment and strongly erosive conditions limit the preservation of volcanic deposits and their accessibility on land. The area offshore southern Iceland preserves information about the depositional fans at medial distance from the volcanic source. Here we use this sedimentary archive to reconstruct the Icelandic eruption record in greater detail. This high resolution geological record allows us to infer eruption frequencies and explosiveness in great detail and contributes to the assessment of Icelandic volcanic hazards, volcano-climate interaction, stratigraphy and palaeoceanographic reconstructions. Eight gravity cores were obtained during RV Poseidon Cruise 457, at 260 to 1,600 m water depths and distances of 130 to 400 km west to southeast of Iceland. The ˜4 to 10 m long sediment cores reach back to the Late Pleistocene (˜68 ka BP; dated by 14C and sedimentation rates), mostly excluding the Holocene. Potential tephra layers were identified by visual inspection and color scans. Volcanic glass shards were analyzed for their major element composition by electron microprobe and assigned to their eruptive source by geochemical fingerprinting. More than 50 primary tephra layers and nearly as many reworked layers were identified, several of which were correlated across the cores. The mostly basaltic tephra shards are derived from the Katla, Grímsvötn-Lakagígar, Bárðarbunga-Veiðivötn, and Hekla volcanic systems. Primary and mixed layers with particles of unique bimodal composition identical to the ˜12 ka BP Vedde-Tephra from the Katla Volcanic System, including rhyolitic particles, were identified in nearly all cores and used as time marker and for inter-core correlation. Tephra layers of unique unknown composition were also identified and

  13. Accumulation reconstruction and water isotope analysis for 1736-1997 of an ice core from the Ushkovsky volcano, Kamchatka, and their relationships to North Pacific climate records

    Science.gov (United States)

    Sato, T.; Shiraiwa, T.; Greve, R.; Seddik, H.; Edelmann, E.; Zwinger, T.

    2014-02-01

    An ice core was retrieved in June 1998 from the Gorshkov crater glacier at the top of the Ushkovsky volcano, in central Kamchatka. This ice core is one of only two recovered from Kamchatka so far, thus filling a gap in the regional instrumental climate network. Hydrogen isotope (δD) analyses and past accumulation reconstructions were conducted for the top 140.7 m of the core, spanning 1736-1997. Two accumulation reconstruction methods were developed and applied with the Salamatin and the Elmer/Ice firn-ice dynamics models, revealing a slightly increasing or nearly stable trend, respectively. Wavelet analysis shows that the ice core records have significant decadal and multi-decadal variabilities at different times. Around 1880 the multi-decadal variability of δD became lost and its average value increased by 6‰. The multi-decadal variability of reconstructed accumulation rates changed at around 1850. Reconstructed accumulation variations agree with ages of moraines in Kamchatka. Ice core signals were significantly correlated with North Pacific sea surface temperature (SST) and surface temperature (2 m temperature). δD correlates with the North Pacific Gyre Oscillation (NPGO) index after the climate regime shift in 1976/1977, but not before that. Therefore, our findings imply that the ice core record contains various information on the local, regional and large-scale climate variability in the North Pacific region. Understanding all detailed mechanisms behind the time-dependent connections between these climate patterns is challenging and requires further efforts towards multi-proxy analysis and climate modelling.

  14. CORE

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin

    2013-01-01

    different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...... intersect. Routes for unicast sessions are agnostic to other sessions and setup beforehand, CORE will then discover and exploit intersecting routes. Our approach allows the inter-session regions to leverage RLNC to compensate for losses or failures in the overhearing or transmitting process. Thus, we...... increase the benefits of XORing by exploiting the underlying RLNC structure of individual flows. This goes beyond providing additional reliability to each individual session and beyond exploiting coding opportunistically. Our numerical results show that CORE outperforms both forwarding and COPE...

  15. CORE

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin

    2013-01-01

    different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...... intersect. Routes for unicast sessions are agnostic to other sessions and setup beforehand, CORE will then discover and exploit intersecting routes. Our approach allows the inter-session regions to leverage RLNC to compensate for losses or failures in the overhearing or transmitting process. Thus, we...... increase the benefits of XORing by exploiting the underlying RLNC structure of individual flows. This goes beyond providing additional reliability to each individual session and beyond exploiting coding opportunistically. Our numerical results show that CORE outperforms both forwarding and COPE...

  16. Signals of Antarctic Circum-polar Wave over the Southern Indian Ocean as recorded in an Antarctica ice core

    Institute of Scientific and Technical Information of China (English)

    XIAO Cunde; CHENG Yanjie; REN Jiawen; LU Longhua; LI Zhongqin; QIN Dahe; ZHOU Xiuji

    2005-01-01

    Oxygen stable isotopic and ionic records, covering a period of 1745-1996, are recovered in DT001 ice core drilled in Princess Elizabeth Land, East Antarctica. Using empirical orthogonal function (EOF) analysis of the annually resolved glaciochemical time series, we find the first EOF (EOF1) represents sea-salt aerosols and is the proxy of sea level pressure (SLP) over a quasi-stationary low in the Southern Indian Ocean (SIO).δ18O represents the sea surface temperature (SST) of the same ocean area. In the past two decades, four climatic waves as represented by SLP and SST proxies are found in the DT001 ice core, which in coincident with four Antarctic Circum-polar Waves (ACW) as revealed by NCEP/NCAR reanalysis. The phase difference between SST and SLP in the ice core is also coincident with that in ACW. Both ice-core record and reanalysis suggest that there were no signals of ACW during 1958-1980, none during the overall recording period between 1745-1996, as there is no regular phase difference between SST and SLP. The ACW signal after early 1980s is probably attributable to the climate shift occurring over Antarctic Peninsula-Drake Passage region.

  17. Anomalies in Water Level Records in Yunnan Caused by the Great Indonesian Earthquakes and Their Significance

    Institute of Scientific and Technical Information of China (English)

    Fu Hong; Wu Chengdong; Liu Qiang; Wang Shiqin; Chen Yan

    2008-01-01

    Two great earthquakes occurred in the sea northwest of Sumatra,Indonesia,on December 26,2004 and March 29,2005.The observation of water levels in Yunnan yielded abundant information about the two earthquakes.This paper presents the water level response to the two earthquakes in Yunnan and makes a preliminary analysis.It is observed that the large earthquake-induced abnormal water level change could be better recorded by analog recording than by digital recording.The large earthquake-caused water level rise or decline may be attributed to the effect of seismic waves that change the stress in tectonic units,and is correlated with the geological structure where the well is located.The water level response mode in a well is totally the same for earthquakes occurring on the same fault and with the same fracture mode.The only difference is that the response amplitude increases with the growth of the earthquake magnitude.

  18. Influence of climatic teleconnections on the temporal isotopic variability as recorded in a firn core from the coastal Dronning Maud Land, East Antarctica

    Indian Academy of Sciences (India)

    Sushant S Naik; Meloth Thamban; A Rajakumar; Witty D’Souza; C M Laluraj; Arun Chaturvedi

    2010-02-01

    Ice and firn core studies provide one of the most valuable tools for understanding the past climate change. In order to evaluate the temporal isotopic variability recorded in ice and its relevance to environmental changes, stable isotopes of oxygen and hydrogen were studied in a firn core from coastal Dronning Maud Land, East Antarctica. The annual 18O profile of the core shows a close relation to the El Niño Southern Oscillation (ENSO) variability. The ENSO indices show significant correlation with the surface air temperatures and 18O values of this region during the austral summer season and support an additional influence related to the Southern Annular Mode (SAM). The correlation between the combined ENSO-SAM index and the summer 18O record seems to have been caused through an atmospheric mechanism. Snow accumulation in this region illustrates a decreasing trend with opposite relationships with 18O data and surface air temperature prior and subsequent to the year 1997. A reorganization of the local water cycle is further indicated by the deuterium excess data showing a shift around 1997, consistent with a change in evaporation conditions. The present study thus illustrates the utility of ice-core studies in the reconstruction of past climate change and suggests possible influence of climatic teleconnections on the snow accumulation rates and isotopic profiles of snow in the coastal regions of east Antarctica.

  19. Links between ice-core based records of West Antarctic dust deposition and Pacific-sector dust generation during the LGM and transition

    Science.gov (United States)

    Kreutz, K. J.; Koffman, B. G.; Putnam, A. E.; Denton, G. H.; Mayewski, P. A.

    2012-12-01

    Chemical concentrations and fluxes measured in ice cores provide a unique archive of information regarding atmospheric aerosol loading and transport processes, and can be used to evaluate climate and environmental processes on timescales ranging from seasonal to millennial. Traditionally, analysis of soluble calcium concentrations has been used as a proxy for terrestrial dust loading, while soluble sodium concentrations serve as a proxy for sea salt aerosol loading. While long time series of these ions have provided valuable information on glacial/interglacial changes in dust and sea salt aerosol, interpretations based on qualitative understanding of modern processes as well as GCM experiments continue to evolve as new records become available. Deep ice core data from East Antarctica has expanded greatly with the EPICA Dome C and EDML records. Here we examine ion data from the Siple Dome, West Antarctica, deep ice core using a semi-empirical modeling approach, and compare results with those from the EPICA cores. We find that calcium (dust) records show coherence at all sites on millennial timescales, which may be related to source conditions, and lack of significant change in atmospheric transport that is consistent with GCM results. However, a lower correlation among Siple Dome and EPICA sites than between EPICA sites suggests there may be additional dust sources that affect West Antarctica. In addition, there is a higher dust flux on all timescales at the lower elevation Siple Dome site, implying a gradient of aerosol loading in the atmosphere. We speculate that dust generation associated with glacially-derived outwash and associated eolian transport, occurring in the Southern Alps of New Zealand during the LGM and transition, may be responsible for a majority of dust reaching the high-latitude South Pacific section (and hence West Antarctica). To test this idea, we compare the high resolution Siple Dome glaciochemical record with glacier moraine chronology data

  20. Reconstructing the Paleo ENSO records from tropical and subtropical ice cores

    Directory of Open Access Journals (Sweden)

    1993-01-01

    dislocations of rainfall regimes in the tropics. Whereas the northern coastal desert regions of Peru experienced abnormally high precipitation, the southern highlands of Peru, where Quelccaya is located, experienced drought. Annual variations in the amount and chemical composition of precipitation accumulating on both polar and alpine (high elevation glaciers produce laminations which allow precise dating of these stratigraphic sequences. This paper examines the interannual climate variability in the Quelccaya ice core records (1 over the last 150 years where a limited amount of documentary data exist by which the ice core data can be evaluated and (2 the longer record covering the last 1500 years where independent evaluation becomes more difficult. The Quelccaya precipitation records derived from the ice cores are compared to the early history of man in South America. There is archeological evidence that, when compared to the Quelccaya net balance record over the last 1500 years, suggests that periods of flourishing highland cultures appear during periods when the mountains are wetter than average and that coastal cultures flourish when the mountains are drier than normal. These data suggest that there may exist longer period ocean/atmospheric links which yield «El Niño-like» precipitation responses on the longer term.

  1. Abrupt Late Holocene Shift in Atmospheric Circulation Recorded by Mineral Dust in the Siple Dome Ice Core, Antarctica

    Science.gov (United States)

    Koffman, B. G.; Goldstein, S. L.; Kaplan, M. R.; Winckler, G.; Bory, A. J. M.; Biscaye, P.

    2015-12-01

    Atmospheric dust directly influences Earth's climate by altering the radiative balance and by depositing micronutrients in the surface ocean, affecting global biogeochemical cycling. In addition, mineral dust particles provide observational evidence constraining past atmospheric circulation patterns. Because dust can originate from both local and distant terrestrial sources, knowledge of dust provenance can substantially inform our understanding of past climate history, atmospheric transport pathways, and differences in aerosol characteristics between glacial and interglacial climate states. Dust provenance information from Antarctic ice cores has until now been limited to sites in East Antarctica. Here we present some of the first provenance data from West Antarctica. We use Sr-Nd isotopes to characterize dust extracted from late Holocene ice (~1000-1800 C.E.) from the Siple Dome ice core. The data form a tight array in Sr-Nd isotope space, with 87Sr/86Sr ranging between ~0.7087 and 0.7102, and ɛNd ranging between ~ -7 and -16. This combination is unique for Antarctica, with low Nd and low Sr isotope ratios compared to high-elevation East Antarctic sites, requiring a dust source from ancient (Archean to early Proterozoic) and unweathered continental crust, which mixes with young volcanic material. Both components are likely sourced from Antarctica. We also observe significant, systematic variability in Sr and Nd isotopic signatures through time, reflecting changes in the mixing ratio of these sources, and hypothesize that these changes are driven by shifts in circulation patterns. A large change occurs over about 10 years at ca. 1125 C.E. (ΔɛNd = +3 and Δ87Sr/86Sr = -0.0014). This shift coincides with changes in climate proxies in Southern Hemisphere paleoclimate records reflecting variability in the Westerlies. We therefore interpret the shift in dust provenance at Siple Dome to be related to larger-scale circulation changes. In general, the observed shifts

  2. Relocation of the Yellow River estuary in 1855 AD recorded in the sediment core from the northern Yellow Sea

    Science.gov (United States)

    Zhou, Xin; Jia, Nan; Cheng, Wenhan; Wang, Yuhong; Sun, Liguang

    2013-12-01

    Relocation of the Yellow River estuary has significant impacts on not only terrestrial environment and human activities, but also sedimentary and ecological environments in coastal seas. The responses of regional geochemical characteristics to the relocation event, however, have not been well studied. In the present study, we performed detailed geochemical elemental analyses of a sediment core from the northern Yellow Sea and studied their geochemical responses to the 1855 AD relocation of the Yellow River estuary. The results show that TOC/TN, Co/Al2O3, Cr/Al2O3, Ni/Al2O3 and Se/Al2O3 ratios all decreased abruptly after 1855 AD, and similar decreases are observed in the sediments of the mud area southwest off the Cheju Island. These abrupt changes are very likely caused by the changes in source materials due to the relocation of the Yellow River estuary from the southern Yellow Sea to the Bohai Sea, which the corresponding decreasing trends caused by the changes in main source materials from those transported by the Liaohe River, the Haihe River and the Luanhe River to those by the Yellow River. Because the events have precise ages recorded in historical archives, these obvious changes in elemental geochemistry of sediments can be used to calibrate age models of related coastal sea sediments.

  3. Hate crimes recording: Recommendations of the international bodies and their significance to Serbia

    Directory of Open Access Journals (Sweden)

    Dokmanović Mirjana

    2015-01-01

    Full Text Available Data recording and keeping the official unique database on hate crimes contributes to increasing visibility of this type of crimes, as well as to formulating effective policies of preventing discrimination, racism and non-tolerance. At the end of 2012, the Republic of Serbia introduced the aggravating circumstance in sentencing crimes motivated by hatred on the basis of race, religion belief, national or ethnical belonging, sex, sexual orientation or gender identity. The Action Plan of the Implementation of the Strategy of Prevention and Protection against Discrimination (2014 foresees introducing the unique database on hate crimes by the end of 2016. The subject of the paper is the analysis of the importance of establishing this type of database from the perspective of acknowledging victims’ rights. The relevant activities and the recommendations of the EU Fundamental Rights Agency (FRA and the OSCE to the member states, with respect to efficient recording data on hate crimes, have been also introduced. The aim of the paper is to contribute developing of the methodology of data recording of hate crimes in the Republic of Serbia in line with the given recommendations of the FRA and the OSCE. [Projekat Ministarstva nauke Republike Srbije, br. 179044: Razvoj metodologije evidentiranja kriminaliteta kao osnova efikasnih mera za njegovo suzbijanje i prevenciju

  4. Detrital dating on drill-core records from McMurdo Sound, Ross Sea (Antarctica)

    Science.gov (United States)

    Zattin, M.; Andreucci, B.; Balestrieri, M.; Olivetti, V.; Pace, D.; Reiners, P. W.; Rossetti, F.; Talarico, F.; Thomson, S. N.

    2012-12-01

    young ages are absent in the onshore portion of the TAM proximal to wells while they are present in regions located to the south. This suggests that the TAM are segmented by transversal lineaments and that significant vertical displacements occurred south of the so-called Discovery Accommodation Zone during the Oligocene. Single grain U-Pb ages on apatites from AND-2A well testify that some volcanism was concurrent with this exhumation event. The location of the volcanic centers is unknown, but aeromagnetic anomalies suggest the presence of subglacial volcanic centers beneath the Ross Ice Shelf and the WAIS. After the Oligocene, the TAM have been in a post-orogenic decay, with exhumation rates of the order of 0.1 km/Ma. As a whole, detrital ages and petrographic data agree on the idea of an ice pattern dominated by south to north trending flow lines parallel to the TAM front. Our record supports the presence of large-scale advance of WAIS across the Ross Sea. Local ice lobes from the TAM glaciers were able to transport debris only during glacial-minima settings while during periods with presence of large ice volumes, W-E flows from the TAM were obstructed by the major flow running S to N.

  5. Two Extreme Climate Events of the Last 1000 Years Recorded in Himalayan and Andean Ice Cores: Impacts on Humans

    Science.gov (United States)

    Thompson, L. G.; Mosley-Thompson, E. S.; Davis, M. E.; Kenny, D. V.; Lin, P.

    2013-12-01

    In the last few decades numerous studies have linked pandemic influenza, cholera, malaria, and viral pneumonia, as well as droughts, famines and global crises, to the El Niño-Southern Oscillation (ENSO). Two annually resolved ice core records, one from Dasuopu Glacier in the Himalaya and one from the Quelccaya Ice Cap in the tropical Peruvian Andes provide an opportunity to investigate these relationships on opposite sides of the Pacific Basin for the last 1000 years. The Dasuopu record provides an annual history from 1440 to 1997 CE and a decadally resolved record from 1000 to 1440 CE while the Quelccaya ice core provides annual resolution over the last 1000 years. Major ENSO events are often recorded in the oxygen isotope, insoluble dust, and chemical records from these cores. Here we investigate outbreaks of diseases, famines and global crises during two of the largest events recorded in the chemistry of these cores, particularly large peaks in the concentrations of chloride (Cl-) and fluoride (Fl-). One event is centered on 1789 to 1800 CE and the second begins abruptly in 1345 and tapers off after 1360 CE. These Cl- and F- peaks represent major droughts and reflect the abundance of continental atmospheric dust, derived in part from dried lake beds in drought stricken regions upwind of the core sites. For Dasuopu the likely sources are in India while for Quelccaya the sources would be the Andean Altiplano. Both regions are subject to drought conditions during the El Niño phase of the ENSO cycle. These two events persist longer (10 to 15 years) than today's typical ENSO events in the Pacific Ocean Basin. The 1789 to 1800 CE event was associated with a very strong El Niño event and was coincidental with the Boji Bara famine resulting from extended droughts that led to over 600,000 deaths in central India by 1792. Similarly extensive droughts are documented in Central and South America. Likewise, the 1345 to 1360 CE event, although poorly documented

  6. Relationship between calcium and atmospheric dust recorded in Guliya ice core

    Institute of Scientific and Technical Information of China (English)

    YAO Tandong; WU Guangjian; PU Jianchen; JIAO Keqin; HUANG Cuilan

    2004-01-01

    By the analyses of Guliya ice core on the Tibetan Plateau, it was found that the calcium (Ca2+) originated from the terrestrial source is the main cation of soluble aerosol and a good proxy of the atmospheric component and environment in the mountain ice core located in the mid-low latitude arid regions. Evident variation of Ca2+ concentration has been found in the Guliya ice core since the Last Interglaciation with two relatively strong increase periods and two weak increase periods. These variations are generally related to climatic changes: high Ca2+ concentration periods coincide with cold periods and low Ca2+ concentration periods coincide with warm periods. However, Ca2+ concentration does not always decrease (increase) with climate warming (cooling). The magnitude and phase of Ca2+ concentration does not always match temperature either. The changes of atmospheric circulation, land surface condition and atmospheric humidity might be important factors which influence Ca2+ concentration besides temperature.

  7. Sea-salt aerosol transport patterns over the Northern Hemisphere inferred from two subarctic ice core records

    Institute of Scientific and Technical Information of China (English)

    YAN Yuping; KANG Shichang; SUN Junying; Paul A. Mayewski; QIN Dahe

    2005-01-01

    Atmospheric circulation reconstruction based on glaciochemical records requires knowledge of chemical concentration controls, such as source, transport pathway and strength. To gain insight into these processes, the relationships between glaciochemical records from two Northern Hemisphere sites (Mt. Logan in Yukon Territory and 20D in southern Greenland) and instrumental sea level pressure (SLP) series are investigated. Calibrations between Mt. Logan sea-salt sodium (ssNa+) concentration and SLP series show that ssNa+ concentrations are closely correlated with the autumntime (SON) Aleutian Low and the summertime (JJA) North Pacific Subtropical High. Both the deepened Aleutian Low and enhanced North Pacific Subtropical High strengthen the transport of sea-salt aerosols from the North Pacific to the Mt. Logan region. Calibrations between 20D ssNa+ concentrations and SLP series indicate that ssNa+ concentrations are closely related to the wintertime (Jan.) Icelandic Low. A deepening of the Icelandic Low strengthens winter storms and frequent cyclogenesis over the North Atlantic and pushes more sea-salt laden air masses to the Greenland ice sheet. Therefore, ice core ssNa+ records from the Mt. Logan region can be considered as a proxy for reconstructing the autumntime Aleutian Low and summertime North Pacific Subtropical High, and the ssNa+ records from Greenland ice core (20D) may provide a proxy for reconstructing the wintertime Icelandic Low.

  8. Paleoceanographic records in the sedimentary cores from the middle Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    LIUYanguang; FUYunxia; DUDewen; MENGXianwei; LIANGRuicai; LITiegang; WUShiying

    2003-01-01

    Two gravity piston cores (Cores 155 and 180) involved in this study were collected from the middle Okinawa Trough. Stratigraphy of the two cores was divided and classified based on the features of planktonic foraminifera oxygen isotope changes together with depositional sequence,millennium-scale climatic event comparison, carbonate cycles and AMS14C dating. Some paleoclimatic information contained in sediments of these cores was extracted to discuss the paleoclimatic change rules and the short-time scale events presented in interglacial period. Analysis on the variation of oxygen isotope values in stage two shows that the middle part of the Okinawa Trough may have been affected by fresh water from the Yellow River and the Yangtze River during the Last Glacial Maximum (LGM). The oxygen isotope value oscillating ranges of the cores have verified that the marginal sea has an amplifying effect on climate changes.The δ13C of benthic foraminifera Uvigerina was lighter in the glacial period than that in the interglacial period, which indicates that the Paleo-Kuroshio's main stream moved eastward and its influence area decreased. According to the temperature difference during the “YD” period existing in Core 180 and other data, we can reach the conclusion that the climatic changes in the middle Okinawa Trough area were controlled by global climatic changes, but some regional factors had also considerable influence on the climatechanges. Some results in this paper support Fairbanks's point that the “YD” event was a brief stagnation of sea level rising during the global warming up procession. Moreover,the falling of sea level in the glacial period weakened the exchange between the bottom water of the Okinawa Trough and the deep water of the northwestern Pacific Ocean and resulted in low oxygen state of bottom water in this area.These procedures are the reasons for carbonate cycle in the Okinawa Trough area being consistent with the “Atlantic type”carbonate cycle.

  9. Paleoceanographic records in the sedimentary cores from the middle Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Two gravity piston cores (Cores 155 and 180) involved in this study were collected from the middle Okinawa Trough. Stratigraphy of the two cores was divided and classified based on the features of planktonic foraminifera oxygen isotope changes together with depositional sequence, millennium-scale climatic event comparison, carbonate cycles and AMS14C dating. Some paleoclimatic information contained in sediments of these cores was extracted to discuss the paleoclimatic change rules and the short-time scale events presented in interglacial period. Analysis on the variation of oxygen isotope values in stage two shows that the middle part of the Okinawa Trough may have been affected by fresh water from the Yellow River and the Yangtze River during the Last Glacial Maximum (LGM). The oxygen isotope value oscillating ranges of the cores have verified that the marginal sea has an amplifying effect on climate changes. The Δ13c of benthic foraminifera Uvigerina was lighter in the glacial period than that in the interglacial period, which indicates that the Paleo-Kuroshio's main stream moved eastward and its influence area decreased. According to the temperature difference during the "YD" period existing in Core 180 and other data, we can reach the conclusion that the climatic changes in the middle Okinawa Trough area were controlled by global climatic changes, but some regional factors had also considerable influence on the climate changes. Some results in this paper support Fairbanks's point that the "YD" event was a brief stagnation of sea level rising during the global warming up procession. Moreover, the falling of sea level in the glacial period weakened the exchange between the bottom water of the Okinawa Trough and the deep water of the northwestern Pacific Ocean and resulted in low oxygen state of bottom water in this area. These procedures are the reasons for carbonate cycle in the Okinawa Trough area being consistent with the "Atlantic type " carbonate cycle.

  10. Tree ring effects and ice core acidities clarify the volcanic record of the first millennium

    OpenAIRE

    M. G. L. Baillie; McAneney, J

    2015-01-01

    In 2012 Plummer et al., in presenting the volcanic chronology of the Antarctic Law Dome ice core, chose to list connections to acid layers in other ice cores and also possible chronological coincidences between ice acid dates and the precise dates of frost damage, and/or reduced growth in North American bristlecone pines. We disagree with the chronological links indicated by Plummer et al. for the period before AD 700, and in this paper we show that a case can be made that b...

  11. Consistently dated records from three Greenland ice cores reveal regional millennial-scale isotope gradients with possible Heinrich Event imprint

    Science.gov (United States)

    Seierstad, Inger K.; Rasmussen, Sune O.

    2014-05-01

    We here present records from the NGRIP, GRIP and GISP2 ice cores tied to the same chronology for the past 104 ka at an unprecedented time resolution. The three ice cores have been linked by matching distinct peaks in volcanic proxy records and other impurity records from the three ice cores, assuming that these layers of elevated impurity content represent the same, instantaneous event in the past at all three sites. In total there are more than 900 identified marker horizons between the three cores including previously published match points, of which we introduce a minor revision. Our matching is independently confirmed by new and existing volcanic ash layers (tephra). The depth-depth relationship from the detailed matching is used to transfer the most recent and widely used Greenland ice core chronology, the GICC05modelext timescale, to the two Summit cores, GRIP and GISP2. Furthermore, we provide gas chronologies for the Summit cores that are consistent with the GICC05modelext timescale by utilizing both existing and new unpublished gas data. A comparison of the GICC05modelext and the former GISP2 timescale reveals major discrepancies in short time intervals during the glacial section. We detect a pronounced change in the relative annual layer thickness between the two Summit sites and NGRIP across the Last Glacial termination and early-to-mid Holocene, which can be explained by a relative accumulation increase at NGRIP compared to the Summit region as response to the onset of the Holocene and the climatic optimum. Between stadials and interstadials we infer that the accumulation contrast typically was nearly 10% greater at Summit compared to at NGRIP. The δ18O temperature-proxy records from NGRIP, GRIP and GISP2 are generally very similar and display a synchronous behavior at climate transitions, but the δ18O differences between Summit and NGRIP is slowly changing over the last glacial-interglacial cycle superimposed by abrupt millennial-to centennial scale

  12. Ice core records of monoterpene- and isoprene-SOA tracers from Aurora Peak in Alaska since 1660s: Implication for climate change variability in the North Pacific Rim

    Science.gov (United States)

    Pokhrel, Ambarish; Kawamura, Kimitaka; Ono, Kaori; Seki, Osamu; Fu, Pingqing; Matoba, Sumio; Shiraiwa, Takayuki

    2016-04-01

    Monoterpene and isoprene secondary organic aerosol (SOA) tracers are reported for the first time in an Alaskan ice core to better understand the biological source strength before and after the industrial revolution in the Northern Hemisphere. We found significantly high concentrations of monoterpene- and isoprene-SOA tracers (e.g., pinic, pinonic, and 2-methylglyceric acids, 2-methylthreitol and 2-methylerythritol) in the ice core, which show historical trends with good correlation to each other since 1660s. They show positive correlations with sugar compounds (e.g., mannitol, fructose, glucose, inositol and sucrose), and anti-correlations with α-dicarbonyls (glyoxal and methylglyoxal) and fatty acids (e.g., C18:1) in the same ice core. These results suggest similar sources and transport pathways for monoterpene- and isoprene-SOA tracers. In addition, we found that concentrations of C5-alkene triols (e.g., 3-methyl-2,3,4-trihydroxy-1-butene, cis-2-methyl 1,3,4-trihydroxy-1-butene and trans-2-methyl-1,3,4-trihydroxy-1-butene) in the ice core have increased after the Great Pacific Climate Shift (late 1970s). They show positive correlations with α-dicarbonyls and fatty acids (e.g., C18:1) in the ice core, suggesting that enhanced oceanic emissions of biogenic organic compounds through the marine boundary layer are recorded in the ice core from Alaska. Photochemical oxidation process for these monoterpene- and isoprene-/sesquiterpene-SOA tracers are suggested to be linked with the periodicity of multi-decadal climate oscillations and retreat of sea ice in the Northern Hemisphere.

  13. Influence of sea ice on ocean water vapor isotopes and Greenland ice core records

    Science.gov (United States)

    Klein, Eric S.; Welker, Jeffrey M.

    2016-12-01

    A warming climate results in sea ice loss and impacts to the Arctic water cycle. The water isotope parameter deuterium excess, a moisture source proxy, can serve as a tracer to help understand hydrological changes due to sea ice loss. However, unlocking the sea ice change signal of isotopes from ice cores requires understanding how sea ice changes impact deuterium excess, which is unknown. Here we present the first isotope data linking a gradient of sea ice extents to oceanic water vapor deuterium excess values. Initial loss of sea ice extent leads to lower deuterium excess moisture sources, and then values progressively increase with further ice loss. Our new process-based interpretation suggests that past rapid (1-3 years) Greenland ice core changes in deuterium excess during warming might not be the result of abrupt atmospheric circulation shifts, but rather gradual loss of sea ice extent at northern latitude moisture sources.

  14. Long memory effect of past climate change in Vostok ice core records

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Yuuki, E-mail: yyama@ed.yama.tus.ac.jp [Department of Mechanical Engineering, Tokyo University of Science, Yamaguchi (Japan); Kitahara, Naoki [Department of Electronics and Computer Science, Tokyo University of Science, Yamaguchi (Japan); Kano, Makoto [Department of Mechanical Engineering, Tokyo University of Science, Yamaguchi (Japan)

    2012-03-20

    Time series analysis of Vostok ice core data has been done for understanding of palaeoclimate change from a stochastic perspective. The Vostok ice core is one of the proxy data for palaeoclimate in which local temperature and precipitation rate, moisture source conditions, wind strength and aerosol fluxes of marine, volcanic, terrestrial, cosmogenic and anthropogenic origin are indirectly stored. Palaeoclimate data has a periodic feature and a stochastic feature. For the proxy data, spectrum analysis and detrended fluctuation analysis (DFA) were conducted to characterize periodicity and scaling property (long memory effect) in the climate change. The result of spectrum analysis indicates there exist periodicities corresponding to the Milankovitch cycle in past climate change occurred. DFA clarified time variability of scaling exponents (Hurst exponent) is associated with abrupt warming in past climate.

  15. Tree ring effects and ice core acidities clarify the volcanic record of the first millennium

    Science.gov (United States)

    Baillie, M. G. L.; McAneney, J.

    2015-01-01

    In 2012 Plummer et al., in presenting the volcanic chronology of the Antarctic Law Dome ice core, chose to list connections to acid layers in other ice cores and also possible chronological coincidences between ice acid dates and the precise dates of frost damage, and/or reduced growth in North American bristlecone pines. We disagree with the chronological links indicated by Plummer et al. for the period before AD 700, and in this paper we show that a case can be made that better linkages between ice acid and tree ring effects occur for this period if the ice chronologies are systematically moved forward by around 7 years, consistent with a hypothesis published by Baillie in 2008. In the paper we seek to explore the proposition that frost damage rings in North American bristlecone pines are a very useful indicator of the dates of certain large explosive volcanic eruptions; the dating of major eruptions being critical for any clear understanding of volcanic forcing. This paper cannot prove that there is an error in the Greenland Ice Core Chronology 2005 (GICC05), and in equivalent ice chronologies from the Antarctic, however, it does provide a coherent argument for an apparent ice dating offset. If the suggested offset were to prove correct it would be necessary to locate where the error occurs in the ice chronologies and in this regard the dating of the increasingly controversial Icelandic Eldgjá eruption in the AD 930s, and the China/Korean Millennium eruption which occurs some 7 years after Eldgjá, may well be critical. In addition, if the offset were to be substantiated it would have implications for the alleged identification of tephra at 429.3 m in the Greenland GRIP core, currently attributed to the Italian volcano Vesuvius and used as a critical zero error point in the GICC05 chronology.

  16. Application of sediment core modelling to interpreting the glacial-interglacial record of Southern Ocean silica cycling

    Directory of Open Access Journals (Sweden)

    A. Ridgwell

    2007-07-01

    Full Text Available Sediments from the Southern Ocean reveal a meridional divide in biogeochemical cycling response to the glacial-interglacial cycles of the late Neogene. South of the present-day position of the Antarctic Polar Front in the Atlantic sector of the Southern Ocean, biogenic opal is generally much more abundant in sediments during interglacials compared to glacials. To the north, an anti-phased relationship is observed, with maximum opal abundance instead occurring during glacials. This antagonistic response of sedimentary properties provides an important model validation target for testing hypotheses of glacial-interglacial change against, particularly for understanding the causes of the concurrent variability in atmospheric CO2. Here, I illustrate a time-dependent modelling approach to helping understand climates of the past by means of the mechanistic simulation of marine sediment core records. I find that a close match between model-predicted and observed down-core changes in sedimentary opal content can be achieved when changes in seasonal sea-ice extent are imposed, whereas the predicted sedimentary response to iron fertilization on its own is not consistent with sedimentary observations. The results of this sediment record model-data comparison supports previous inferences that the changing cryosphere is the primary driver of the striking features exhibited by the paleoceanographic record of this region.

  17. Glacial/interglacial wetland, biomass burning, and geologic methane emissions constrained by dual stable isotopic CH4 ice core records

    Science.gov (United States)

    Bock, Michael; Schmitt, Jochen; Beck, Jonas; Seth, Barbara; Chappellaz, Jérôme; Fischer, Hubertus

    2017-07-01

    Atmospheric methane (CH4) records reconstructed from polar ice cores represent an integrated view on processes predominantly taking place in the terrestrial biogeosphere. Here, we present dual stable isotopic methane records [δ13CH4 and δD(CH4)] from four Antarctic ice cores, which provide improved constraints on past changes in natural methane sources. Our isotope data show that tropical wetlands and seasonally inundated floodplains are most likely the controlling sources of atmospheric methane variations for the current and two older interglacials and their preceding glacial maxima. The changes in these sources are steered by variations in temperature, precipitation, and the water table as modulated by insolation, (local) sea level, and monsoon intensity. Based on our δD(CH4) constraint, it seems that geologic emissions of methane may play a steady but only minor role in atmospheric CH4 changes and that the glacial budget is not dominated by these sources. Superimposed on the glacial/interglacial variations is a marked difference in both isotope records, with systematically higher values during the last 25,000 y compared with older time periods. This shift cannot be explained by climatic changes. Rather, our isotopic methane budget points to a marked increase in fire activity, possibly caused by biome changes and accumulation of fuel related to the late Pleistocene megafauna extinction, which took place in the course of the last glacial.

  18. Non-climatic signal in ice core records: lessons from Antarctic mega-dunes

    Directory of Open Access Journals (Sweden)

    A. Ekaykin

    2015-12-01

    Full Text Available We present the results of glaciological investigations in the mega-dune area located 30 km to the east from Vostok Station (central East Antarctica implemented during the 58th, 59th and 60th Russian Antarctic Expedition (January 2013–January 2015. Snow accumulation rate and isotope content (δD, δ18O and δ17O were measured along the 2 km profile across the mega-dune ridge accompanied by precise GPS altitude measurements and GPR survey. It is shown that the spatial variability of snow accumulation and isotope content covaries with the surface slope. The accumulation rate regularly changes by one order of magnitude within the distance −1. The full cycle of the dune drift is thus about 410 years. Since the spatial anomalies of snow accumulation and isotopic composition are supposed to drift with the dune, an ice core drilled in the mega-dune area would exhibit the non-climatic 410 year cycle of these two parameters. We simulated a vertical profile of snow isotopic composition with such a non-climatic variability, using the data on the dune size and velocity. This artificial profile is then compared with the real vertical profile of snow isotopic composition obtained from a core drilled in the mega-dune area. We note that the two profiles are very similar. The obtained results are discussed in terms of interpretation of data obtained from ice cores drilled beyond the mega-dune areas.

  19. Using Water Vapor Isotope Observations from above the Greenland Ice Sheet to improve the Interpretation of Ice Core Water Stable Isotope Records

    Science.gov (United States)

    Steen-Larsen, H. C.; Masson-Delmotte, V.; Risi, C. M.; Yoshimura, K.; Werner, M.; Butzin, M.; Brun, E.; Landais, A.; Bonne, J. L.; Dahl-Jensen, D.

    2014-12-01

    Water stable isotope data from Greenland ice cores provide key paleoclimatic information. For the purpose of improving the climatic interpretation from ice core records, a monitoring of the isotopic composition δ18O and δD at several height levels (up to 13 meter) of near-surface water vapor, precipitation and snow in the first 0.5 cm surface layer has been conducted during three summers (2010-2012) at NEEM, NW Greenland. We compare the observed water vapor isotopic composition with model outputs from three isotope-enabled general circulation models: LMDZiso, isoGSM, ECHAM-wiso. This allows us to benchmark the models and address effect of model resolution, effect of transport, effect of isotope parameterization, and representation of significant source region contributions. We find for all models that the simulated isotopic value δD are significantly biased towards too enriched values. A bias, which is only partly explained by the air temperature. The simulated amplitude in d-excess variations is ~50% smaller than observed and the simulated average summer level is ~10‰ lower than in observations. Using back trajectories we observe water vapor of Arctic origin to have a high d-excess fingerprint. This fingerprint is not observed in the GCMiso simulations indicating a problem of simulating accurately the Arctic hydrological cycle. The bias in the simulated δD and d-excess water vapor is similar to the already-documented bias in the simulated δD and d-excess of Greenland ice core records. This suggests that if we improve the simulation of the water vapor isotopic composition we might also improve the simulation of the ice core isotope record. During periods between precipitation events, our data demonstrate parallel changes of δ18O and d-excess in surface snow and near-surface vapor. The changes in δ18O of the vapor are similar or larger than those of the snow δ18O. It is estimated using the CROCUS snow model that 6 to 20% of the surface snow mass is

  20. An ice-core-based record of biomass burning in the Arctic and Subarctic, 1750–1980

    OpenAIRE

    WHITLOW, S.; Mayewski, P; J. Dibb; Holdsworth, G; Twickler, M.

    2011-01-01

    Ammonium records from 3 ice cores, 20D and GISP2 (Greenland) and Mt. Logan (Yukon), covering the period from 1750 to the 1980s are analyzed. For each data set, samples with NH4+ concentrations greater than one standard deviation above the mean value also tend to be enriched in NO3- and K+, similar to the chemical composition of aerosols from aged biomass burning plumes. We believe the NH4+ spikes originate from biomass burning events. There is not a one to one correspondence between documente...

  1. Changes in Black Carbon Deposition to Antarctica from Two Ice Core Records, A.D. 1850-2000

    Science.gov (United States)

    Bisiaux, Marion M.; Edward, Ross; McConnell, Joseph R.; Curran, Mark A. J.; VanOmmen, Tas D.; Smith, Andrew M.; Neumann, Thomas A.; Pasteris, Daniel R.; Penner, Joyce E.; Taylor, Kendrick

    2012-01-01

    Continuous flow analysis was based on a steady sample flow and in-line detection of BC and other chemical substances as described in McConnell et al. (2007). In the cold room, previously cut one meter ice core sticks of 3x3cm, are melted continuously on a heated melter head specifically designed to eliminate contamination from the atmosphere or by the external parts of the ice. The melted ice from the most inner part of the ice stick is continuously pumped by a peristaltic pump and carried to a clean lab by Teflon lines. The recorded signal is continuous, integrating a sample volume of about 0.05 mL, for which the temporal resolution depends on the speed of melting, ice density and snow accumulation rate at the ice core drilling site. For annual accumulation derived from the WAIS and Law Dome ice cores, we assumed 3.1 cm water equivalent uncertainty in each year's accumulation from short scale spatial variability (glaciological noise) which was determined from several measurements of annual accumulation in multiple parallel ice cores notably from the WAIS Divide ice core site (Banta et al., 2008) and from South Pole site (McConnell et al., 1997; McConnell et al., 2000). Refractory black carbon (rBC) concentrations were determined using the same method as in (Bisiaux et al., 2011) and adapted to continuous flow measurements as described by (McConnell et al., 2007). The technique uses a single particle intracavity laser induced incandescence photometer (SP2, Droplet Measurement Technologies, Boulder, Colorado) coupled to an ultrasonic nebulizer/desolvation (CETAC UT5000) Flow Injection Analysis (FIA). All analyses, sample preparation etc, were performed in a class 100 cleanroom using anti contamination "clean techniques". The samples were not acidified.

  2. Non-climatic signal in ice core records: lessons from Antarctic megadunes

    Science.gov (United States)

    Ekaykin, Alexey; Eberlein, Lutz; Lipenkov, Vladimir; Popov, Sergey; Scheinert, Mirko; Schröder, Ludwig; Turkeev, Alexey

    2016-06-01

    We present the results of glaciological investigations in the megadune area located 30 km to the east of Vostok Station (central East Antarctica) implemented during the 58th, 59th and 60th Russian Antarctic Expedition (January 2013-2015). Snow accumulation rate and isotope content (δD, δ18O and δ17O) were measured along the 2 km profile across the megadune ridge accompanied by precise GPS altitude measurements and ground penetrating radar (GPR) survey. It is shown that the spatial variability of snow accumulation and isotope content covaries with the surface slope. The accumulation rate regularly changes by 1 order of magnitude within the distance negative correlation with the snow accumulation. Analysing dxs / δD and 17O-excess / δD slopes (where dxs = δD - 8 ṡ δ18O and 17O-excess = ln(δ17O / 1000 + 1) -0.528 ṡ ln (δ18O / 1000 + 1)), we conclude that the spatial variability of the snow isotopic composition in the megadune area could be explained by post-depositional snow modifications. Using the GPR data, we estimated the apparent dune drift velocity (4.6 ± 1.1 m yr-1). The full cycle of the dune drift is thus about 410 years. Since the spatial anomalies of snow accumulation and isotopic composition are supposed to drift with the dune, a core drilled in the megadune area would exhibit the non-climatic 410-year cycle of these two parameters. We simulated a vertical profile of snow isotopic composition with such a non-climatic variability, using the data on the dune size and velocity. This artificial profile is then compared with the real vertical profile of snow isotopic composition obtained from a core drilled in the megadune area. We note that the two profiles are very similar. The obtained results are discussed in terms of interpretation of data obtained from ice cores drilled beyond the megadune areas.

  3. Early stages of core segregation recorded by Fe isotopes in an asteroidal mantle

    OpenAIRE

    Barrat, Jean-Alix; Rouxel, O; Wang, K; Moynier, F; Yamaguchi, A; Bischoff, A; Langlade, J

    2015-01-01

    International audience; Ureilites displays  56 Fe values higher than average chondrite. 29-Segregation of Fe-sulfide melts explains the high  56 Fe values in ureilites. 30-Formation of a core can begin at very low degrees of melting through the circulation of a Fe-S melt 31 through a silicate mantle. 32 33 Earth and Planetary Science Letters, in press (11/3/15). 34 2 35 Abstract 36 37 Ureilite meteorites are achondrites that are debris of the mantle of a now disrupted 38 differentiated aste...

  4. The ice-core record - Climate sensitivity and future greenhouse warming

    Science.gov (United States)

    Lorius, C.; Raynaud, D.; Jouzel, J.; Hansen, J.; Le Treut, H.

    1990-01-01

    The prediction of future greenhouse-gas-warming depends critically on the sensitivity of earth's climate to increasing atmospheric concentrations of these gases. Data from cores drilled in polar ice sheets show a remarkable correlation between past glacial-interglacial temperature changes and the inferred atmospheric concentration of gases such as carbon dioxide and methane. These and other palaeoclimate data are used to assess the role of greenhouse gases in explaining past global climate change, and the validity of models predicting the effect of increasing concentrations of such gases in the atmosphere.

  5. Biochemical and stable carbon isotope records of mangrove derived organic matter in the sediment cores

    Digital Repository Service at National Institute of Oceanography (India)

    Manju, M.N.; Resmi, P.; RatheeshKumar, C.S.; Gireeshkumar, T.R.; Chandramohanakumar, N.; Joseph, M.M.

    components were recorded in surface sediments, with a dominance of carbohydrates followed by lipids and proteins. Protein/carbohydrate ratio was found to be <1 in the entire study region indicating a large content of aged and/or non-living organic matter...

  6. Global ice volume during MIS 3 inferred from a sea-level analysis of sedimentary core records in the Yellow River Delta

    Science.gov (United States)

    Pico, Tamara; Mitrovica, Jerry X.; Ferrier, Ken L.; Braun, Jean

    2016-11-01

    Estimates of global ice volume during the glacial phase of the most recent ice age cycle are characterized by significant uncertainty, reflecting the relative paucity of geological constraints on sea level relevant to this time interval. For example, during the middle stages of Marine Isotope Stage 3, published estimates of peak global mean sea level (GMSL) relative to the present range from -25 m to -87 m. The large uncertainty in GMSL at MIS 3 has significant implications for estimates of the rate of ice growth in the period leading to the Last Glacial Maximum (∼26 ka). We refine estimates of global ice volume during MIS 3 by employing sediment cores in the Bohai and Yellow Sea that record a migration of the paleoshoreline at ∼50-37 ka through a transition from marine to brackish conditions. In particular, we correct relative sea level at these sites for contamination due to glacial isostatic adjustment using a sea-level calculation that includes a gravitationally self-consistent treatment of sediment redistribution and compaction, and estimate a peak global mean sea level of -38 ± 7 m during the interval 50-37 ka. With suitable sedimentary core records, the approach described herein can be extended to refine existing constraints on global ice volume across the entire glacial period.

  7. Geochemistry of drill core headspace gases and its significance in gas hydrate drilling in Qilian Mountain permafrost

    Science.gov (United States)

    Lu, Zhengquan; Rao, Zhu; He, Jiaxiong; Zhu, Youhai; Zhang, Yongqin; Liu, Hui; Wang, Ting; Xue, Xiaohua

    2015-02-01

    Headspace gases from cores are sampled in the gas hydrate drilling well DK-8 in the Qilian Mountain permafrost. Gas components and carbon isotopes of methane from headspace gas samples are analyzed. The geochemical features of the headspace gases along the well profile are compared with occurrences of gas hydrate, and with the distribution of faults or fractures. Their geochemical significance is finally pointed out in gas hydrate occurrences and hydrocarbon migration. Results show high levels of hydrocarbon concentrations in the headspace gases at depths of 149-167 m, 228-299 m, 321-337 m and 360-380 m. Visible gas hydrate and its associated anomalies occur at 149-167 m and 228-299 m; the occurrence of high gas concentrations in core headspace gases was correlated to gas hydrate occurrences and their associated anomalies, especially in the shallow layers. Gas compositions, gas ratios of C1/ΣC1-5, C1/(C2 + C3), iC4/nC4, and iC5/nC5, and carbon isotopic compositions of methane (δ13C1, PDB‰) indicate that the headspace gases are mainly thermogenic, partly mixed with biodegraded thermogenic sources with small amounts derived from microbial sources. Faults or fracture zones are identified at intervals of 149-167 m, 228-299 m, 321-337 m, and near 360-380 m; significantly higher gas concentrations and lower dryness ratio were found in the headspace gases within the fault or fracture zones compared with areas above these zones. In the shallow zones, low dryness ratios were observed in headspace gases in zones where gas hydrate and faults or fracture zones were found, suggesting that faults or fracture zones serve as migration paths for gases in the deep layers and provide accumulation space for gas hydrate in the shallow layers of the Qilian Mountain permafrost.

  8. Revised estimates of Greenland ice sheet thinning histories based on ice-core records

    DEFF Research Database (Denmark)

    Lecavalier, B.S.; Milne, G.A.; Fisher, D.A.;

    2013-01-01

    -based reconstructions and, to some extent, the estimated elevation histories. A key component of the ice core analysis involved removing the influence of vertical surface motion on the dO signal measured from the Agassiz and Renland ice caps. We re-visit the original analysis with the intent to determine if the use...... height changes on the dO signal from the two ice cores. This procedure is complicated by the fact that dO contained in Agassiz ice is influenced by land height changes distant from the ice cap and so selecting a single location at which to compute the land height signal is not possible. Uncertainty...... in this selection is further complicated by the possible influence of Innuitian ice during the early Holocene (12-8 ka BP). Our results indicate that a more accurate treatment of the uplift correction leads to elevation histories that are, in general, shifted down relative to the original curves at GRIP, NGRIP, DYE...

  9. Ductile strain rate recorded in the Symvolon syn-extensional plutonic body (Rhodope core complex, Greece)

    Science.gov (United States)

    Cirrincione, Rosolino; Fazio, Eugenio; Ortolano, Gaetano; Fiannacca, Patrizia; Kern, Hartmut; Mengel, Kurt; Pezzino, Antonino; Punturo, Rosalda

    2016-04-01

    The present contribution deals with quantitative microstructural analysis, which was performed on granodiorites of the syn-tectonic Symvolon pluton (Punturo et al., 2014) at the south-western boundary of the Rhodope Core Complex (Greece). Our purpose is the quantification of ductile strain rate achieved across the pluton, by considering its cooling gradient from the centre to the periphery, using the combination of a paleopiezometer (Shimizu, 2008) and a quartz flow law (Hirth et al., 2001). Obtained results, associated with a detailed cooling history (Dinter et al., 1995), allowed us to reconstruct the joined cooling and strain gradient evolution of the pluton from its emplacement during early Miocene (ca. 700°C at 22 Ma) to its following cooling stage (ca. 500-300°C at 15 Ma). Shearing temperature values were constrained by means of a thermodynamic approach based on the recognition of syn-shear assemblages at incremental strain; to this aim, statistical handling of mineral chemistry X-Ray maps was carried out on microdomains detected at the tails of porphyroclasts. Results indicate that the strain/cooling gradients evolve "arm in arm" across the pluton, as also testified by the progressive development of mylonitic fabric over the magmatic microstructures approaching the host rock. References • Dinter, D. A., Macfarlane, A., Hames, W., Isachsen, C., Bowring, S., and Royden, L. (1995). U-Pb and 40Ar/39Ar geochronology of the Symvolon granodiorite: Implications for the thermal and structural evolution of the Rhodope metamorphic core complex, northeastern Greece. Tectonics, 14 (4), 886-908. • Shimizu, I. (2008). Theories and applicability of grain size piezometers: The role of dynamic recrystallization mechanisms. Journal of Structural Geology, 30 (7), 899-917. • Hirth, G., Teyssier, C., and Dunlap, J. W. (2001). An evaluation of quartzite flow laws based on comparisons between experimentally and naturally deformed rocks. International Journal of Earth

  10. The agricultural history of human-nitrogen interactions as recorded in ice core δ15N-NO3-

    Science.gov (United States)

    Felix, J. David; Elliott, Emily M.

    2013-04-01

    The advent and industrialization of the Haber Bosch process in the early twentieth century ushered in a new era of reactive nitrogen distributions on Earth. Since the appearance of the first commercial scale Haber Bosch fertilizer plants, fertilizer application rates have greatly increased in the U.S. While the contributions of fertilizer runoff to eutrophication and anoxic dead zones in coastal regions have been well-documented, the potential influences of increased fertilizer applications on air quality and precipitation chemistry are poorly constrained. Here we combine a 255-year record of precipitation nitrate isotopes preserved in a Greenland ice core, historical reconstructions of fertilizer application rates, and field characterization of the isotopic composition of nitrogen oxides produced biogenically in soils, to provide new constraints on the contributions of biogenic emissions to North American NOx inventories. Our results indicate that increases in twentieth century commercial fertilizer use led to large increases in soil NO, a byproduct released during nitrification and denitrification reactions. These large shifts in soil NO production are evidenced by sharp declines in ice core δ15N-NO3- values. Further, these results suggest that biogenic NOx emissions are underestimated by two to four fold in the U.S. NOx emission inventories used to construct global reactive nitrogen budgets. These results demonstrate that nitrate isotopes in ice cores, coupled with newly constrained δ15N-NOx values for NOx emission sources, provide a novel means for estimating contemporary and historic contributions from individual NOx emission sources to deposition.

  11. Historical anthropogenic contributions to mercury accumulation recorded by a peat core from Dajiuhu montane mire, central China.

    Science.gov (United States)

    Li, Yuanping; Ma, Chunmei; Zhu, Cheng; Huang, Run; Zheng, Chaogui

    2016-09-01

    Mercury (Hg) accumulation records spanning the last 16,000 years before present (yr BP, relative to AD 1950) were derived from a peat core collected from Dajiuhu mire, central China. The natural Hg concentration and accumulation rate (free from anthropogenic influence) were 135.5 ± 53.9 ng g(-1) and 6.5 ± 4.5 μg m(-2) yr(-1), respectively. The increase in Hg flux that started from a core depth of 96.5 cm (3358 cal yr BP) is independent of soil erosion and organic matter content. We attribute this to an increase in atmospheric Hg deposition derived from regional anthropogenic activities. Anthropogenic Hg accumulation rates (Hg-ARA) in the pre-industrial period peaked during the Ming and the early Qing dynasties (582-100 cal yr BP), with Hg-ARA of 9.9-24.6 and 10.7-24.4 μg m(-2) yr(-1), respectively. In the industrial interval (post∼1850 AD), Hg-ARA increased progressively and reached 32.7 μg m(-2) yr(-1) at the top of the core. Our results indicate the existence of regional atmospheric Hg pollution spanning the past ∼3400 years, and place recent Hg enrichment in central China in a broader historical context.

  12. Geostatistical analysis and isoscape of ice core derived water stable isotope records in an Antarctic macro region

    Science.gov (United States)

    Hatvani, István Gábor; Leuenberger, Markus; Kohán, Balázs; Kern, Zoltán

    2017-09-01

    Water stable isotopes preserved in ice cores provide essential information about polar precipitation. In the present study, multivariate regression and variogram analyses were conducted on 22 δ2H and 53 δ18O records from 60 ice cores covering the second half of the 20th century. Taking the multicollinearity of the explanatory variables into account, as also the model's adjusted R2 and its mean absolute error, longitude, elevation and distance from the coast were found to be the main independent geographical driving factors governing the spatial δ18O variability of firn/ice in the chosen Antarctic macro region. After diminishing the effects of these factors, using variography, the weights for interpolation with kriging were obtained and the spatial autocorrelation structure of the dataset was revealed. This indicates an average area of influence with a radius of 350 km. This allows the determination of the areas which are as yet not covered by the spatial variability of the existing network of ice cores. Finally, the regional isoscape was obtained for the study area, and this may be considered the first step towards a geostatistically improved isoscape for Antarctica.

  13. δ18O records in water vapor and an ice core from the eastern Pamir Plateau: Implications for paleoclimate reconstructions

    Science.gov (United States)

    Yu, Wusheng; Tian, Lide; Risi, Camille; Yao, Tandong; Ma, Yaoming; Zhao, Huabiao; Zhu, Haifeng; He, You; Xu, Baiqing; Zhang, Hongbo; Qu, Dongmei

    2016-12-01

    This study is the first to examine δ18O in daily water vapor at Taxkorgan on the eastern Pamir Plateau. The results show that changes in observed and simulated δ18O values in water vapor/precipitation at the event scale (using a LMDZ-iso model) were mainly affected by temperature. The influences of humidity, precipitation amount, and different moisture sources, such as the westerlies, local evaporated moisture, and polar air masses, on δ18O values are comparatively weak. The combination of the δ18O record from the Muztagata ice core, 58 km away from the study area, and the LMDZ-iso simulated annual δ18O pattern in precipitation at Taxkorgan also demonstrated that temperature, and particularly the temperature of the regions over which the southern branch of the westerlies flows, is the most important factor controlling δ18O variations. The results from this study area, which is dominated by the westerlies throughout the year, are markedly different from those derived from parts of the Tibetan Plateau that are dominated by the combined influences of the westerlies in winter and the Indian monsoon in summer. The results suggested that the eastern Pamir Plateau is an ideal location to reconstruct past temperature variations and that the δ18O records preserved in ice cores from the region are a suitable and robust proxy for temperature.

  14. Correlation between high-resolution climate records from a Nanjing stalagmite and GRIP ice core during the last glaciation

    Institute of Scientific and Technical Information of China (English)

    WANG; Yongjin

    2001-01-01

    [1]Dansgaard, W., Clausen, H. B., Gundestrup, N. et al., A new Greenland deep ice core, Science, 1982, 218: 1273.[2]Dansgaard, W., Johnsen, S. J., Clausen, H. B. et al., Evidence for general instability of past climate from a 250-Kyr ice-core record, Nature, 1993, 364: 218.[3]Bond, G. C., Broecker, W. S., Johnsen, S. J. et al., Correlation between climate records from North Atlantic sediments and Greenland ice, Nature, 1993, 365: 143.[4]Bond, G. C., Lotti, R., Iceberg discharges into the North Atlantic on millennial time scales during the last glaciation, Science, 1995, 267: 1005.[5]Kotilainen, A. T., Shackleton, N. J., Rapid climate variability in the North Pacific Ocean during the past 950 000 years, Nature, 1995, 267: 323.[6]Lowell, T. V., Heusser, C. J., Sandensrn, B. G. et al., Interhemispheric correlation of late Pleistocene glacial events, Science, 1995, 269: 1541.[7]Porter, S. C., An, Z. S., Correlation between climate events in the North Atlantic and China during the last glaciation, Nature, 1995, 375: 305.[8]Guo, Z. T., Liu, T. S., Wu, N. Q. et al., Heinrich-rhythem pulses of climate recorded in loess of the last two glaciations, Quaternary Science (in Chinese), 1996, (1): 21.[9]Lu, H. Y., Guo, Z. T., Wu, N. Q., Paleomonsoon evolution and Heinrich events: evidences from the Loess Plateau and the South China Sea, Quaternary Science (in Chinese), 1996, (1): 11.[10]Zhang, M. L., Yuan, D. X., Lin, Y. S., Isotopic ages and its paleoclimate significance of a stalagmite from Xiangshui Cave in Guangyang County, Guangxi Province, Carsologica Sinica (in Chinese), 1998, 17(4): 311.[11]Edwards, R. L., Chen, J. H., Wasserburg, G. J., 238U-234U-230Th-232Th systematic and precise measurement of time over the past 500 000 years, Earth and Planetary Science Letter, 1986/1987, 81: 175.[12]McCrea, J. M., The isotopic Chemistry of carbonates and a paleotemperature-scale, Journal of Chemical Physics, 1950, 18: 849.[13

  15. Ranges of moisture-source temperatures estimated from Antarctic ice core stable isotope records over the glacial-interglacial cycles

    Directory of Open Access Journals (Sweden)

    R. Uemura

    2012-01-01

    Full Text Available A single isotope ratio (δD or δ18O of water is widely used as an air-temperature proxy in Antarctic ice cores. These isotope ratios, however, do not solely depend on air-temperature but also on the extent of distillation of heavy isotopes out of atmospheric water vapor from an oceanic moisture source to a precipitation site. The temperature changes at the oceanic moisture source (ΔTsource and at the precipitation site (ΔTsite can be retrieved by using deuterium-excess (d data. A new d record from Dome Fuji, Antarctica is produced spanning the past 360 000 yr and compared with records from Vostok and EPICA Dome C ice cores. To retrieve ΔTsource and ΔTsite information, different linear regression equations have been proposed using theoretical isotope distillation models. A major source of uncertainty lies in the coefficient of regression, βsite which is related to the sensitivity of d to ΔTsite. We show that different ranges of temperature and selections of isotopic model outputs may increase the value of βsite by a factor of two. To explore the impacts of this coefficient on the reconstructed temperatures, we apply for the first time the exact same methodology to the isotope records from the three Antarctica ice cores. We show that uncertainties in the βsite coefficient strongly affect (i the glacial-interglacial magnitude of ΔTsource; (ii the imprint of obliquity in ΔTsource and in the site-source temperature gradient. By contrast, we highlight the robustness of ΔTsite reconstruction using water isotopes records.

  16. Sedimentary record of polycyclic aromatic hydrocarbons in a sediment core from the Pearl River Estuary, South China.

    Science.gov (United States)

    Liu, G Q; Zhang, G; Li, X D; Li, J; Peng, X Z; Qi, S H

    2005-01-01

    Owing to the hydrodynamic and sedimentation conditions, the western shoal of the Pearl River Estuary (PRE) is known to be an important sink of terrestrial substances including particle-associated pollutants from the Pearl River Delta (PRD) region. In this study, we report the sedimentary record of polycyclic aromatic hydrocarbons (PAHs) during the 20(th) century in a sediment core from the western shoal of the PRE. The summation PAH concentration ranged from 59 ng g(-1) to 330 ng g(-1) in the core with two distinct peaks. An initial increase of summation PAH concentration was found around the 1860s. The amounts of PAHs remained relatively constant for roughly 100 years, followed by the first peak in the 1950s. Then, there was a decrease in PAH concentration and flux in the 1960s and 1970s. A sharp increase of PAH concentration was observed in the early 1980s with a maximum concentration in the 1990s. The PAH diagnostic ratios indicated that the PAHs in the sediment core were mainly of pyrolytic origin, and that atmospheric deposition and land runoff may serve as the important pathways for PAHs input to the sediment. The Gross Domestic Product (GDP) was used as an index of socioeconomic development in the PRD region, which was correlated positively with the changes of PAH concentration and flux in the sediment core. The rapid increase in vehicle numbers and energy consumption in the region in the last two decades may have contributed to the rapid PAH increase since the early 1980s. The results clearly elucidated the impact of regional economic development on the estuarine environment.

  17. Geochemical characteristics and their significances of rare-earth elements in deep-water well core at the Lingnan Low Uplift Area of the Qiongdongnan Basin

    Institute of Scientific and Technical Information of China (English)

    SUN Zhipeng; ZHAI Shikui; XIU Chun; LIU Xinyu; ZONG Tong; LUO Wei; LIU Xiaofeng; CHEN Kui; LI Na

    2014-01-01

    Miocene, the provenance has ceaselessly expanded from proximal to distal realm, embodying a characteristic of multi-source sedimentation. In the core strata with 31.5, 28.4, 25.5, 23, and 16 Ma from today, the geochemical parameters of REEs and Th/Sc ratio have significant saltation, embodying the tectonic movement events in the evolution of the Qiongdongnan Basin. In the tectonic evolution history of the South China Sea, the South China Sea Movement (34–25 Ma BP, early expansion of the South China Sea), Baiyun Movement (23 Ma BP), late expansion movement (23.5–16.5 Ma BP), expansion-settlement transition, and other important events are all clearly recorded by the geochemi-cal characteristics of REEs in the core.

  18. The Significance of Minimally Invasive Core Needle Biopsy and Immunohistochemistry Analysis in 235 Cases with Breast Lesions

    Institute of Scientific and Technical Information of China (English)

    Yun Niu; Tieju Liu; Xuchen Cao; Xiumin Ding; Li Wei; Yuxia Gao; Jun Liu

    2009-01-01

    OBJECTIVE To evaluate core needle biopsy (CNB) as a mini-mally invasive method to examine breast lesions and discuss the clinical significance of subsequent immunohistochemistry (IHC)analysis.METHODS The clinical data and pathological results of 235 pa-tients with breast lesions, who Received CNB before surgery, were analyzed and compared. Based on the results of CNB done before surgery, 87 out of 204 patients diagnosed as invasive carcinoma were subjected to immunodetection for p53, c-erbB-2, ER and PR.The morphological change of cancer tissues in response to chemo-therapy was also evaluated.RESULTS In total of 235 cases receiving CNB examination, 204 were diagnosed as invasive carcinoma, reaching a 100% consistent rate with the surgical diagnosis. Sixty percent of the cases diag-nosed as non-invasive carcinoma by CNB was identified to have the presence of invading elements in surgical specimens, and simi-larly, 50% of the cases diagnosed as atypical ductal hyperplasia by CNB was confirmed to be carcinoma by the subsequent result of excision biopsy. There was no significant difference between the CNB biopsy and regular surgical samples in positive rate of im-munohistochemistry analysis (p53, c-erbB-2, ER and PR; P > 0.05).However, there was significant difference in the expression rate of p53 and c-erbB-2 between the cases with and without morphologi-cal change in response to chemotherapy (P < 0.05). In most cases with p53 and c-erbB-2 positive, there was no obvious morphologi-cal change after chemotherapy. CONCLUSION CNB is a cost-effective diagnostic method with minimal invasion for breast lesions, although it still has some limi-tations. Immunodetection on CNB tissue is expected to have great significance in clinical applications.

  19. Centennial-scale records of total organic carbon in sediment cores from the South Yellow Sea, China

    Science.gov (United States)

    Zhu, Qing; Lin, Jia; Hong, Yuehui; Yuan, Lirong; Liu, Jinzhong; Xu, Xiaoming; Wang, Jianghai

    2017-05-01

    Global carbon cycling is a significant factor that controls climate change. The centennial-scale variations in total organic carbon (TOC) contents and its sources in marginal sea sediments may reflect the influence of human activities on global climate change. In this study, two fine-grained sediment cores from the Yellow Sea Cold Water Mass of the South Yellow Sea were used to systematically determine TOC contents and stable carbon isotope ratios. These results were combined with previous data of black carbon and 210Pb dating from which we reconstructed the centennial-scale initial sequences of TOC, terrigenous TOC (TOCter) and marine autogenous TOC (TOCmar) after selecting suitable models to correct the measured TOC (TOCcor). These sequences showed that the TOCter decreased with time in the both cores while the TOCmar increased, particularly the rapid growth in core H43 since the late 1960s. According to the correlation between the Huanghe (Yellow) River discharge and the TOCcor, TOCter, or TOCmar, we found that the TOCter in the two cores mainly derived from the Huanghe River and was transported by it, and that higher Huanghe River discharge could strengthen the decomposition of TOCmar. The newly obtained initial TOC sequences provide important insights into the interaction between human activities and natural processes.

  20. Incorporating trnH-psbA to the core DNA barcodes improves significantly species discrimination within southern African Combretaceae

    Directory of Open Access Journals (Sweden)

    Jephris Gere

    2013-12-01

    Full Text Available Recent studies indicate that the discriminatory power of the core DNA barcodes (rbcLa + matK for land plants may have been overestimated since their performance have been tested only on few closely related species. In this study we focused mainly on how the addition of complementary barcodes (nrITS and trnH-psbA to the core barcodes will affect the performance of the core barcodes in discriminating closely related species from family to section levels. In general, we found that the core barcodes performed poorly compared to the various combinations tested. Using multiple criteria, we finally advocated for the use of the core + trnH-psbA as potential DNA barcode for the family Combretaceae at least in southern Africa. Our results also indicate that the success of DNA barcoding in discriminating closely related species may be related to evolutionary and possibly the biogeographic histories of the taxonomic group tested.

  1. 800 year ice-core record of nitrogen deposition in Svalbard linked to ocean productivity and biogenic emissions

    Directory of Open Access Journals (Sweden)

    I. A. Wendl

    2014-09-01

    Full Text Available We present the records of the two nitrogen species nitrate (NO3− and ammonium (NH4+ analysed in a new ice core from Lomonosovfonna, Svalbard, in the Eurasian Arctic covering the period 1222–2009. We investigate the emission sources and the influence of melt on the records. During the 20th century both records are influenced by anthropogenic pollution from Eurasia. In pre-industrial times NO3− is highly correlated with methane-sulfonate (MSA on decadal time-scales, which we explain by a fertilising effect. Enhanced atmospheric NO3− concentrations and the corresponding nitrogen input to the ocean trigger the growth of dimethyl-sulfide-(DMS-producing phytoplankton. Increased DMS production results in elevated fluxes to the atmosphere where it is oxidised to MSA. Eurasia was presumably the main source area also for pre-industrial NO3−, but a more exact source apportionment could not be performed based on our data. This is different for NH4+, where biogenic ammonia (NH3 emissions from Siberian boreal forests were identified as the dominant source of pre-industrial NH4+. Changes in melt at the Lomonosovfonna glacier are excluded as major driving force for the decadal variations of the investigated compounds.

  2. Significance of the hepatitis C virus (HCV core antigen as an alternative plasma marker of active HCV infection

    Directory of Open Access Journals (Sweden)

    Daniel HDJ

    2007-01-01

    Full Text Available Purpose: To evaluate the role of core antigen (Ortho trak-C assay as a marker of active HCV infection in comparison to HCV RNA as detected by reverse transcription polymerase chain reaction (RT-PCR. Methods: This evaluation was carried out during January 2000 to December 2003 in HCV infected individuals who were treatment naοve or were on anti-viral therapy. Additionally, sequential plasma samples from patients on clinical follow-up were included in this study. A total of 167 samples from 61 patients were tested by trak-C and RT-PCR. HCV RNA detection was achieved by a RT-PCR. Trak-C assay results were also compared in a limited proportion of these samples with known HCV viral load and genotype. Results: Of 167 samples tested, 56.9% were RNA positive and 43.1% were RNA negative while 50.3% were trak-C positive and 49.7% were trak-C negative, yielding a sensitivity of 85.3% and a specificity of 95.8% for the trak-C assay (Kappa co-efficient = 0.8. The concentration of HCVcAg and HCV RNA showed significant correlation (n=38, r=0.334, P =0.04. The trak-C assay detected the most prevalent HCV genotypes in India without significant difference ( P =0.335. The difference between mean absorbance values of HCV RNA positive samples compared to HCV RNA negative samples in the trak-C assay was highly significant ( P < 0.000. Qualitative results of trak-C assay and RT-PCR were comparable in 93% of follow-up samples. Conclusions: Trak-C assay can be recommended for confirmation of HCV infection and follow-up in laboratories with resource-poor facilities.

  3. Alteration of Crystalline and Glassy Basaltic Protolith by Seawater as Recorded by Drill Core and Drill Cutting Samples

    Science.gov (United States)

    Fowler, A. P.; Zierenberg, R. A.; Schiffman, P.

    2015-12-01

    The major and trace element composition of hydrothermally altered basaltic drill core and drill cutting samples from the seawater recharged Reykjanes geothermal system in Iceland are compared to unaltered surface flows from the Reykjanes Peninsula compiled from the literature. Trace element characteristics of deep (>2000 m) core samples record bimodal compositions similar to trace element enriched and trace element depleted Reykjanes Ridge basalts. Drill cuttings (350-3000 m) overwhelmingly reflect the more common trace element enriched igneous precursor. Crystalline protoliths (dolerite dykes and pillow lava cores) are depleted in Cs, Rb, K, and Ba (± Pb and Th) relative to an unaltered equivalent, despite variations in the extent of alteration ranging from from minor chloritization with intact igneous precursor minerals through to extensive chloritization and uralitization. Glassy protoliths (dyke margins, pillow edges, and hyaloclastites) show similar depletions of Cs, Rb, K, and Ba, but also show selective depletions of the light rare earth elements (LREE) La, Ce, Pr, Nd and Eu due to extensive recrystallization to hydrothermal hornblende. Lower grade alteration shows less pronounced decoupling of LREE and is likely controlled by a combination of Cl complexation in the seawater-derived recharge fluid, moderated by anhydrite and epidote precipitation. These results suggest that alteration of glassy protolith in seawater-recharged systems is an important contribution to the consistently light rare earth and Eu enriched patterns observed in seafloor hydrothermal fluids from basaltic systems. An important conclusion of this study is that that drill cuttings samples are strongly biased toward unaltered rock and more resistant alteration minerals including epidote and quartz potentially resulting in misidentification of lithology and extent of alteration.

  4. Century-long Record of Black Carbon in an Ice Core from the Eastern Pamirs: Estimated Contributions from Biomass Burning

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Mo; Xu, B.; Kaspari, Susan D.; Gleixner, Gerd; Schwab, Valerie; Zhao, Huabiao; Wang, Hailong; Yao, Ping

    2015-08-01

    We analyzed refractory black carbon (rBC) in an ice core spanning 1875-2000 AD from Mt. Muztagh Ata, the Eastern Pamirs, using a Single Particle Soot Photometer (SP2). Additionally a pre-existing levoglucosan record from the same ice core was used to differentiate rBC that originated from open fires, energy-related combustion of biomass, and fossil fuel combustion. Mean rBC concentrations increased four-fold since the mid-1970s and reached maximum values at the end of 1980s. The observed decrease of the rBC concentrations during the 1990s was likely driven by the economic recession of former USSR countries in Central Asia. Levoglucosan concentrations showed a similar temporal trend to rBC concentrations, exhibiting a large increase around 1980 AD followed by a decrease in the 1990s that was likely due to a decrease in energy-related biomass combustion. The time evolution of levoglucosan/rBC ratios indicated stronger emissions from open fires during the 1940s-1950s, while the increase in rBC during the 1980s-1990s was caused from an increase in energy-related combustion of biomass and fossil fuels.

  5. Decapitation of high-altitude glaciers on the Tibetan Plateau revealed by ice core tritium and mercury records

    Directory of Open Access Journals (Sweden)

    S. C. Kang

    2015-01-01

    Full Text Available Two ice cores were retrieved from high elevations (~ 5800 m a.s.l. at Mt. Nyainqentanglha and Mt. Geladaindong in the southern to inland Tibetan Plateau. The combined analysis of tritium (3H, 210Pb, mercury tracers, along with other chemical records, revealed that the two coring sites had not received net ice accumulation since at least the 1950s and 1980s, respectively, implying an annual ice loss rate of more than several hundred millimeter water equivalent over these periods. Both mass balance modeling at the sites and in situ data from nearby glaciers confirmed a continuously negative mass balance (or mass loss in the region due to the dramatic warming in the last decades. Along with a recent report on Naimona'nyi Glacier in the Himalaya, the findings suggest that glacier decapitation (i.e., the loss of the accumulation zone is a wide-spread phenomenon from the southern to inland Tibetan Plateau even at the summit regions. This raises concerns over the rapid rate of glacier ice loss and associated changes in surface glacier runoff, water availability, and sea levels.

  6. Association between atmospheric circulation patterns and firn-ice core records from the Inilchek glacierized area, central Tien Shan, Asia

    Science.gov (United States)

    Aizen, V.B.; Aizen, E.M.; Melack, J.M.; Kreutz, K.J.; Cecil, L.D.

    2004-01-01

    Glacioclimatological research in the central Tien Shan was performed in the summers of 1998 and 1999 on the South Inilchek Glacier at 5100-5460 m. A 14.36 m firn-ice core and snow samples were collected and used for stratigraphic, isotopic, and chemical analyses. The firn-ice core and snow records were related to snow pit measurements at an event scale and to meteorological data and synoptic indices of atmospheric circulation at annual and seasonal scales. Linear relationships between the seasonal air temperature and seasonal isotopic composition in accumulated precipitation were established. Changes in the ??18O air temperature relationship, in major ion concentration and in the ratios between chemical species, were used to identify different sources of moisture and investigate changes in atmospheric circulation patterns. Precipitation over the central Tien Shan is characterized by the lowest ionic content among the Tien Shan glaciers and indicates its mainly marine origin. In seasons of minimum precipitation, autumn and winter, water vapor was derived from the and and semiarid regions in central Eurasia and contributed annual maximal solute content to snow accumulation in Tien Shan. The lowest content of major ions was observed in spring and summer layers, which represent maximum seasonal accumulation when moisture originates over the Atlantic Ocean and Mediterranean and Black Seas. Copyright 2004 by the American Geophysical Union.

  7. Reconstruction of Antarctic climate change using ice core proxy records from the coastal Dronning Maud Land, East Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Thamban, M.; Laluraj, C.M.; Naik, S.S.; Chaturvedi, A.

    , possibly through atmospheric scavenging. The nitrate (NO sub (3) –) profile exhibit significant temporal shifts than that of the sulphate (SO sub (4) sup (2)–), with a major shift around 1750 AD. The changes in NO sub (3) – record are synchronous...

  8. The paleomagnetism of single silicate crystals: Recording geomagnetic field strength during mixed polarity intervals, superchrons, and inner core growth

    Science.gov (United States)

    Tarduno, J. A.; Cottrell, R. D.; Smirnov, A. V.

    2006-03-01

    The basic features of the geomagnetic reversal chronology of the last 160 million years are well established. The relationship between this history and other features of the field, however, has been elusive. The determination of past field strength (paleointensity) is especially challenging. Commonly accepted results have come from analyses of bulk samples of lava. Historic lavas have been shown to faithfully record the past field strength when analyzed using the Thellier double-heating method. Data from older lavas, however, tend to show effects of in situ and laboratory-induced alteration. Here we review an alternative approach. Single plagioclase crystals can contain minute magnetic inclusions, 50-350 nm in size, that are potential high-fidelity field recorders. Thellier experiments using plagioclase feldspars from an historic lava on Hawaii provide a benchmark for the method. Rock magnetic data from older lavas indicate that the feldspars are less susceptible to experimental alteration than bulk samples. This resistance is likely related to the lack of clays. In addition, magnetic minerals are sheltered by the encasing silicate matrix from natural alteration that can otherwise transform the well-defined thermoremanent magnetization into an irresolute chemical remanent magnetization. If there is a relationship between geomagnetic reversal frequency and paleointensity, it should be best expressed during superchrons, intervals with few (or no) reversals. Thellier data sets based on single plagioclase crystals from lavas erupted during the Cretaceous Normal Polarity Superchron (~83-120 million years ago) suggest a strong (>12 × 1022 Am2), stable field, consistent with an inverse relationship between reversal frequency and paleointensity. Superchrons may represent times when the pattern of core-mantle boundary heat flux allows the geodynamo to operate at peak efficiency, as suggested in some numerical models. Thellier data from single plagioclase crystals formed

  9. High-resolution glacial and deglacial record of atmospheric methane by continuous-flow and laser spectrometer analysis along the NEEM ice core

    Directory of Open Access Journals (Sweden)

    J. Chappellaz

    2013-05-01

    Full Text Available The Greenland NEEM (North Greenland Eemian Ice Drilling operation in 2010 provided the first opportunity to combine trace-gas measurements by laser spectroscopic instruments and continuous-flow analysis along a freshly drilled ice core in a field based setting. We present the resulting atmospheric methane (CH4 record covering the time period from 107.7 to 9.5 ka b2k (thousand years before 2000 AD. Companion discrete CH4 measurements are required to transfer the laser spectroscopic data from a relative to an absolute scale. However, even on a relative scale, the high-resolution CH4 dataset significantly improves our knowledge of past atmospheric methane concentration changes. New significant sub-millennial-scale features appear during interstadials and stadials, generally associated with similar changes in water isotopic ratios of the ice, a proxy for local temperature. In addition to the mid-point of Dansgaard/Oeschger (D/O CH4 transitions usually used for cross-dating, sharp definition of the start and end of these events brings precise depth markers (with ±20 cm uncertainty for further cross-dating with other ice core or paleo records, e.g. speleothems. The method also provides an estimate of CH4 rates of change. The onsets of D/O events in the methane signal show a more rapid rate of change than their endings. The rate of CH4 increase associated with the onsets of D/O events progressively declines from 1.7 to 0.6 ppbv yr−1 in the course of Marine Isotope Stage 3. The largest observed rate of increase takes place at the onset of D/O event #21 and reaches 2.5 ppbv yr−1.

  10. Two likely stratospheric volcanic eruptions in the 1450s C.E. found in a bipolar, subannually dated 800 year ice core record

    Science.gov (United States)

    Cole-Dai, Jihong; Ferris, David G.; Lanciki, Alyson L.; Savarino, Joël.; Thiemens, Mark H.; McConnell, Joseph R.

    2013-07-01

    An 800 year volcanic record is constructed from high-resolution chemical analysis of recently obtained West Antarctica and central Greenland ice cores. The high accuracy and precision of the ice core chronologies are a result of dating by annual ice layer counting. Nineteen bipolar volcanic signals in this record represent large, explosive eruptions in the tropics with probable climatic impact. One of the two bipolar volcanic signals dated at 1453 and 1459 is probably left by the eruption of the submarine volcano Kuwae in the tropical Pacific, one of the largest volcanic eruptions in the last millennium. The discovery of the two signals in the 1450s casts doubt on the eruption year of 1452 or 1453 for Kuwae based on previous ice core records. The volcanic sulfate deposition patterns in this bipolar record suggest that the later signal is likely from the Kuwae eruption in 1458, although a firm attribution is not possible. Sulfur isotope composition in the volcanic sulfate in the central Greenland cores indicates that both eruptions in the 1450s injected sulfur gases into the stratosphere with probable impact on the global climate. These results are in agreement with tree ring records showing two short cold episodes during that decade. The bipolar volcanic record supports the hypothesis that unusually active volcanism in the thirteenth century contributed to the onset of the Little Ice Age and another active period in the mid fifteenth century may have helped to sustain the Little Ice Age.

  11. The methane record of Daansgard-Oeschger event 17 in Vostok 4G-2 ice core: effects of layered bubble trapping and smoothing

    Science.gov (United States)

    Fourteau, Kévin; Faïn, Xavier; Martinerie, Patricia; Landais, Amaëlle; Ekaykin, Alexey A.; Lipenkov, Vladimir Ya.; Chappellaz, Jérôme

    2017-04-01

    This work aims to characterise and quantify the modification and loss of past atmospheric information recorded in ice cores due to gas trapping mechanisms. For this purpose a very high resolution methane record of the DO event 17 in Vostok 4G-2 ice core has been measured by continuous flow analysis and laser spectroscopy. This is the first time that the gas of a very low accumulation core, about 1.3cm.yr-1 ice equivalent, is measured using a continuous method. The measurements reveal numerous anomalous layers a couple of centimetres thick. These anomalous layers differ in methane mixing ratio from adjacent layers by about plus or minus 50ppbv. Their amplitude and uneven distribution along the ice core can be reproduced by a simple layered bubble trapping model. After removing the layering anomalies, the DO 17 recorded in the Vostok core is clearly smoother than in the WAIS Divide record, a much higher accumulation rate site. This is consistent with previous observations and general understanding, since high accumulation firns sink and densify faster and the trapping phase of gases is less spread over time. However the smoothing of the DO event in the Vostok ice core turns out to be less important and to contain higher frequencies than expected. Finally we developed a method to infer the gas age distribution enclosed in ice cores by comparison with a high frequency atmospheric scenario, such as the WAIS Divide record. This approach allows to constrain gas age distributions in climatic conditions which have no modern analogue.

  12. The Rock Record Has It About Right—No Significant Continental Crust Formation Prior to 3.8 Ga

    Science.gov (United States)

    Vervoort, J. D.; Kemp, A. I.; Fisher, C.; Bauer, A.; Bowring, S. A.

    2015-12-01

    Although limited in its exposed extent and by its quality of preservation, the geologic record through the first two billion years of Earth's history provides surprisingly tight constraints on the growth and evolution of continental crust. The magmatic zircon record for this period is dominated by Neoarchean U-Pb ages, with greatly diminishing abundance of older rocks and no known zircon bearing rocks much older than 4.0 Ga. A similar pattern exists for the ages of detrital zircons but with important addition of zircons as old as 4.4 Ga, mostly from the Jack Hills metaconglomerate. It has been suggested that this represents an artefact of preservation rather than the actual production rate of older crust, with the implication that large volumes of older crust have been destroyed by various recycling processes. This undoubtedly has happened to some extent, but there is considerable uncertainty as to how much has been destroyed and the nature of the early-formed crust. Here is where the long-lived radiogenic isotopic record, particularly Lu-Hf, can provide important information on the sources of the zircons by integrating age and tracer isotopic information in not only the same sample or zircon but even in the same domain of zircon. Using the most robust data from zircon and whole rock samples, excluding those with unconstrained ages and mixed-domain analyses, the most radiogenic Hf isotope compositions are characterized by ~ chondritic Hf isotopic compositions from 4.4 to ~ 3.8 Ga and a nearly linear evolution trend from epsilon Hf of 0 at 3.8 Ga to ~ epsilon Hf of +16 at present. There remains no evidence from the Hf isotope record for widespread mantle depletion prior to 3.8 Ga. Excluding the Jack Hills zircons, there is a conspicuous lack of pre 3.9 Ga zircons in even the oldest sediments1. This indicates that crust prior to 3.8 Ga was likely small in volume and/or effectively recycled back into the mantle on short time scales and did not result in significant

  13. A High-Resolution Lateglacial Pollen Record from the SG06 Lake Suigetsu Core, Japan: Contrasting Mechanisms of Holocene and Bølling Warming

    Science.gov (United States)

    Nakagawa, T.; Bronk Ramsey, C.; Bryant, C. L.; Staff, R.; Brauer, A.; Lamb, H.; Schlolaut, G.; Marshall, M.; Tarasov, P. E.; Gotanda, K.; Haraguchi, T.; Yonenobu, H.; Tada, R.; Yokoyama, Y.

    2013-12-01

    The Lateglacial to the early Holocene part of the SG06 sediment core, recovered in 2006 from Lake Suigetsu and the outline of which was reported in 2009 AGU fall meeting, was analysed for pollen at high resolution (<15 years). The pollen data were quantitatively analysed to infer climate indices. The results were robustly correlated to NGRIP and Hulu data using independent and reliable chronologies (GICC05, Hulu U-Th, and SG062012). The shift from the Lateglacial to the early Holocene in Lake Suigetsu was very abrupt, possibly over an interval of just one year. Within dating errors, the transition was synchronous with the Holocene onset recorded in the NGRIP Greenland ice core. In contrast, warming at the onset of the Lateglacial interstadial (equivalent to the GI-1/Bølling interval) was earlier by a few centuries at Lake Suigetsu than in Greenland. In the light of this new data, the Hulu cave record also appears to support a multi-centennial Asian lead in the shift towards the Lateglacial interstadial. During the transition, during which Japan was already warm but Greenland was still cold, atmospheric circulation over Eurasia was perturbed and the frequency of heavy stormy events in Japan significantly increased. This unstable situation ended when the N. Atlantic region also warmed, allowing re-establishment of the longitudinal temperature balance across the Eurasian continent. The difference in spatio-temporal structure of the two warming events (Holocene and Lateglacial interstadial onsets) strongly implies that their mechanisms were different. The Holocene onset was probably a sudden mode shift that involved both Pacific and Atlantic regions, whereas the delayed onset of the Lateglacial interstadial in Greenland implies that the transition started gradually elsewhere, before passing a threshold that suddenly propagated the warming to the N. Atlantic. Rapid re-starting of the thermo-haline circulation could have provided this threshold mechanism.

  14. Trends in North Pacific Ocean-Atmosphere Variability During the Common Era Inferred From a New Mt. Hunter (Denali, Alaska) 1200-Year Ice Core Stable Isotope Record

    Science.gov (United States)

    Kreutz, K. J.; Osterberg, E. C.; Winski, D.; Wake, C. P.; Campbell, S. W.; Introne, D.; Ferris, D. G.

    2016-12-01

    The mechanisms and outcomes of teleconnections between the tropical and North Pacific regions over the past 2000 years remain elusive. Correctly assessing the impact on the Aluetian Low, storm tracks, and general hydroclimate during the Medieval Climate Anomaly (MCA), transition to the Little Ice Age (LIA), and then into the 20th century likely requires a suite of high resolution paleoclimate data from the region. Here we present an ice core stable water isotope developed from two surface to bedrock ice cores recovered in 2013 from the high elevation Mt. Hunter plateau in Denali National Park, Alaska. The cores were processed using a continuous flow analysis (CFA) system, and dated using a combination of annual chemical and dust signals, and radioactive and volcanic horizons. The resulting annually-resolved timescale currently spans 2013-810AD. We analyzed 6000 stable water isotope samples for d18O, dD, and the derived deuterium excess (dxs) parameter, yielding a subannually resolved isotope record from 2013-1234AD, and 1-3 year resolution from 1233-810AD. We initially focus on the dxs record, as there are trends in the data that correspond to the large scale climate features of the Common Era. The dxs record shows decreased values during the MCA and a rise into the LIA, consistent with several other regional paleoclimate records. The most obvious feature of the dxs record is a pronounced decrease beginning in the mid 19th century and continuing to present. We note that this trend mirrors a rise in snow accumulation rate in the Denali ice core record, suggesting coherent changes in North Pacific climate dynamics over the past 150 years. Understanding the dxs record in terms of ocean source region temperature and/or relative humidity remains a challenge, and we discuss progress on interpreting the Denali isotope record and fitting these data into a broader paleoclimate context.

  15. An ice core record of near-synchronous global climate changes at the Bølling transition

    Science.gov (United States)

    Rosen, Julia L.; Brook, Edward J.; Severinghaus, Jeffrey P.; Blunier, Thomas; Mitchell, Logan E.; Lee, James E.; Edwards, Jon S.; Gkinis, Vasileios

    2014-06-01

    The abrupt warming that initiated the Bølling-Allerød interstadial was the penultimate warming in a series of climate variations known as Dansgaard-Oeschger events. Despite the clear expression of this transition in numerous palaeoclimate records, the relative timing of climate shifts in different regions of the world and their causes are subject to debate. Here we explore the phasing of global climate change at the onset of the Bølling-Allerød using air preserved in bubbles in the North Greenland Eemian ice core. Specifically, we measured methane concentrations, which act as a proxy for low-latitude climate, and the 15N/14N ratio of N2, which reflects Greenland surface temperature, over the same interval of time. We use an atmospheric box model and a firn air model to account for potential uncertainties in the data, and find that changes in Greenland temperature and atmospheric methane emissions at the Bølling onset occurred essentially synchronously, with temperature leading by 4.5 years. We cannot exclude the possibility that tropical climate could lag changing methane concentrations by up to several decades, if the initial methane rise came from boreal sources alone. However, because even boreal methane-producing regions lie far from Greenland, we conclude that the mechanism that drove abrupt change at this time must be capable of rapidly transmitting climate changes across the globe.

  16. Isotopic and chemical analyses of a temperate firn core from a Chinese alpine glacier and its regional climatic significance

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Mt. Yulong is the southernmost currently glacier-covered area in Eurasia, including China. There are 19 sub-tropical temperate glaciers on the mountain, controlled by the south-western monsoon climate. In the summer of 1999, a firn core, 10. 10 m long, extending down to glacier ice, was recovered in the accumulation area of the largest glacier, Baishui No. 1. Periodic variations of climatic signals above 7. 8 m depth were apparent, and net accumulation of four years was identified by the annual oscillations of isotopic and ionic composition. The boundaries of annual accumulation were confirmed by higher values of electrical conductivity and pH, and by dirty refreezing ice layers at the levels of summer surfaces. Calculated mean annual net accumulation from 1994/1995 to 1997/1998 was about 900 mm water equivalent. The amplitude of isotopic variations in the profile decreased with increasing depth, and isotopic homogenization occurred below 7. 8 m as a result of meltwater percolation. Variations of δ18O above 7. 8 m showed an approximate correlation with the winter climatic trend at Li Jiang Station, 25 km away. Concentrations of Ca2+ and Mg2+ were much higher than those of Na+ and K+ , indicating that the air masses for precipitation were mainly from a continental source, and that the core material accumulated during the winter period. The close correspondence of C1- and Na+ indicated their common origin. Very low concentrations of SO2-4 and NO3- suggest that pollution caused by human activities is quite low in the area. The mean annual net accumulation in the core and the estimated ablation indicate that the average annual precipitation above the glacier's equilibrium line is 2400 - 3150 mm, but this needs to be confirmed by long term observation of mass balance.

  17. Formal definition and dating of the GSSP (Global Stratotype Section and Point) for the base of the Holocene using the Greenland NGRIP ice core, and selected auxiliary records

    DEFF Research Database (Denmark)

    Walker, Mike; Johnsen, Sigfus Johann; Rasmussen, Sune Olander;

    2009-01-01

    The Greenland ice core from NorthGRIP (NGRIP) contains a proxy climate record across the Pleistocene-Holocene boundary of unprecedented clarity and resolution. Analysis of an array of physical and chemical parameters within the ice enables the base of the Holocene, as reflected in the first signs...

  18. The Olorgesailie Drilling Project (ODP): a high-resolution drill core record from a hominin site in the East African Rift Valley

    Science.gov (United States)

    Dommain, R.; Potts, R.; Behrensmeyer, A. K.; Deino, A. L.

    2014-12-01

    The East African rift valley contains an outstanding record of hominin fossils that document human evolution over the Plio-Pleistocene when the global and regional climate and the rift valley itself changed markedly. The sediments of fossil localities typically provide, however, only short time windows into past climatic and environmental conditions. Continuous, long-term terrestrial records are now becoming available through core drilling to help elucidate the paleoenvironmental context of human evolution. Here we present a 500,000 year long high-resolution drill core record obtained from a key fossil and archeological site - the Olorgesailie Basin in the southern Kenya Rift Valley, well known for its sequence of archeological and faunal sites for the past 1.2 million years. In 2012 two drill cores (54 and 166 m long) were collected in the Koora Plain just south of Mt. Olorgesailie as part of the Olorgesailie Drilling Project (ODP) to establish a detailed climate and ecological record associated with the last evidence of Homo erectus in Africa, the oldest transition of Acheulean to Middle Stone Age technology, and large mammal species turnover, all of which are documented in the Olorgesailie excavations. The cores were sampled at the National Lacustrine Core Facility. More than 140 samples of tephra and trachytic basement lavas have led to high-precision 40Ar/39Ar dating. The cores are being analyzed for a suite of paleoclimatic and paleoecological proxies such as diatoms, pollen, fungal spores, phytoliths, ostracodes, carbonate isotopes, leaf wax biomarkers, charcoal, and clay mineralogy. Sedimentological analyses, including lithological descriptions, microscopic smear slide analysis (242 samples), and grain-size analysis, reveal a highly variable sedimentary sequence of deep lake phases with laminated sediments, diatomites, shallow lake and near shore phases, fluvial deposits, paleosols, interspersed carbonate layers, and abundant volcanic ash deposits. Magnetic

  19. Reconstructing a flash flood record from the late Holocene in sediment cores from the Gulf of Aqaba-Eilat (Red Sea)

    Science.gov (United States)

    Kalman, Akos; Katz, Timor; Mathalon, Alysse; Hill, Paul; Goodman, Beverly

    2017-04-01

    Episodic rainfall over the hyperarid desert may cause flash floods in ephemeral rivers surrounding the Gulf of Aqaba-Eilat. These floods constitute an essential factor in the region's ecology but may also damage infrastructure and risk lives. Some floods reach the head of the Gulf of Aqaba and their sediments deposit on the shelf where they play an important role in structuring the ecosystem, such as limiting the distribution of coral reefs. Much of these sediments are later transported further offshore to the deep basin. To date, there is no continuous record of flash floods that may provide a long term perspective of the frequency and magnitude of flash floods in this region and their shifts over time; anticipation of future risks caused by local flash floods (or prolonged droughts) is therefore largely speculative. This ongoing study aims to reconstruct to the best possible resolution a late Holocene flood record in the GOA and trends therein. The methodology includes chemical and physical characterization of the flood deposits and to recognize them in the microstratigraphy (1 cm intervals) of dated cores from the shallow and deep seafloor. Our results show that characteristics of suspended flood sediment, e.g. grain size distribution and elemental composition are distinguishable and recognizable in the stratigraphy of the cores. Flood sediment concentration changes are clearly detectable in 20-40 cm push cores and a 312 cm long pneumatic core from the shelf (at 13 m depth in front of the floods' drainage outlet) as well as in a 80 cm long core from 450 m depth. Flood sediment stratigraphy in a 312 cm long pneumatic core shows recurring fluctuations, but also three more long term environmental shifts that require further explanation. These promising results will be complemented with micropaleontological analysis of the cores as well as additional dating to reconstruct a long term record of floods and related climatic conditions in the area of the GOA making it

  20. Variations in temperature and precipitation in the past 2000 a on the Xizang (Tibet) Plateau——Guliya ice core record

    Institute of Scientific and Technical Information of China (English)

    姚檀栋; L.G.Thompson; 秦大河; 田立德; 焦克勤; 杨志红; 谢超

    1996-01-01

    The past temperature and precipitation variations are recorded precisely and continuously in μ18O and glacial accumulation records in the Guliya ice core. Fight warm periods and seven cold periods can be distinguished in the past 2000 a. Of the four most intensive cold periods, three are in the Little Ice Age and one in the 11th - 12th century. The variation of precipitation is relatively small compared with that of temperature. Five humid periods and four dry periods occurred in the past 2 000 a. The long-term variation of temperature is positively correlated with that of precipitation according to the Guliya ice core record, but the variation of precipitation lags behind the variation of temperature.

  1. Using lead isotopes and trace element records from two contrasting Lake Tanganyika sediment cores to assess watershed – Lake exchange

    Science.gov (United States)

    Odigie, Kingsley; Cohen, A.D.; Swarzenski, Peter W.; Flegal, R

    2014-01-01

    Lead isotopic and trace element records of two contrasting sediment cores were examined to reconstruct historic, industrial contaminant inputs to Lake Tanganyika, Africa. Observed fluxes of Co, Cu, Mn, Ni, Pb, and Zn in age-dated sediments collected from the lake varied both spatially and temporally over the past two to four centuries. The fluxes of trace elements were lower (up to 10-fold) at a mid-lake site (MC1) than at a nearshore site (LT-98-58), which is directly downstream from the Kahama and Nyasanga River watersheds and adjacent to the relatively pristine Gombe Stream National Park. Trace element fluxes at that nearshore site did not measurably change over the last two centuries (1815–1998), while the distal, mid-lake site exhibited substantial changes in the fluxes of trace elements – likely caused by changes in land use – over that period. For example, the flux of Pb increased by ∼300% from 1871 to 1991. That apparent accelerated weathering and detrital mobilization of lithogenic trace elements was further evidenced by (i) positive correlations (r = 0.77–0.99, p < 0.05) between the fluxes of Co, Cu, Mn, Ni, Pb, and Zn and those of iron (Fe) at both sites, (ii) positive correlations (r = 0.82–0.98, p < 0.01, n = 9) between the fluxes of elements (Al, Co, Cu, Fe, Mn, Ni, Pb, and Zn) and the mass accumulation rates at the offshore site, (iii) the low enrichment factors (EF < 5) of those trace elements, and (iv) the temporal consistencies of the isotopic composition of Pb in the sediment. These measurements indicate that accelerated weathering, rather than industrialization, accounts for most of the increases in trace element fluxes to Lake Tanganyika in spite of the development of mining and smelting operations within the lake’s watershed over the past century. The data also indicate that the mid-lake site is a much more sensitive and useful recorder of environmental changes than the nearshore site. Furthermore, the lead isotopic compositions

  2. Significance of pregnancy test false negative results due to elevated levels of β-core fragment hCG.

    Science.gov (United States)

    Johnson, Sarah; Eapen, Saji; Smith, Peter; Warren, Graham; Zinaman, Michael

    2017-01-01

    Very high levels of β-core fragment human chorionic gonadotrophin (βcf-hCG) are reported to potentially cause false negative results in point-of-care (POC)/over-the-counter (OTC) pregnancy tests. To investigate this further, women's daily early morning urine samples, collected prior to conception and during pregnancy, were analysed for intact, free β-, and βcf-hCG. The proportion of βcf-hCG was found to be related to that of hCG produced and in circulation. Therefore, best practice for accuracy testing of POC/OTC pregnancy tests would be to test devices against clinical samples containing high levels of βcf-hCG as well as standards spiked with biologically relevant ratios.

  3. Sedimentary record of ice divide migration and ice streams in the Keewatin core region of the Laurentide Ice Sheet

    Science.gov (United States)

    Hodder, Tyler J.; Ross, Martin; Menzies, John

    2016-06-01

    The Aberdeen Lake region of central mainland Nunavut is a former core region of the Laurentide Ice Sheet that is characterized by streamlined glacial landforms classified into multiple crosscutting flow sets and near continuous till blanket. The presence of widespread till near the centre of the Keewatin Ice Dome raises questions about its origin. Detailed drillcore logging revealed a complex stratigraphy consisting of at least 6 till units, variably preserved across the study area. Till provenance analysis indicates deposition by near opposite-trending ice flow phases, interpreted as evidence of reconfiguration of the Keewatin Ice Divide. At the surface, large north-northwesterly aligned landforms are present across the study area. The till stratigraphy within these landforms indicates the same NNW ice flow phase is responsible for considerable till production. This ice flow phase is also correlated to a long regional dispersal train of erratics toward the Gulf of Boothia. The production of an extensive, thick (~ 12 m), till sheet during the NNW-trending ice flow phase occurred far from the ice margin at a time of extensive ice cover of mainland Nunavut, likely from an east-west oriented ice divide. A deglacial westerly trending ice flow phase formed small drumlins atop the larger NNW streamlined till ridges and deposited a surficial till unit that is too thin to mask the NNW flow set across the study area. It is proposed that the Boothia paleo-ice stream catchment area propagated deep into the Laurentide Ice Sheet and contributed to significant till production in this core region of the Keewatin Sector prior to the westerly ice flow shift. The apparent relationship between till thickness and the size of the associated or correlated drumlins, flow sets, and dispersal trains indicates complex erosion/deposition interplay is involved in the formation of streamlined subglacial landforms.

  4. Long-term Records of Pacific Salmon Abundance From Sediment Core Analysis: Relationships to Past Climatic Change, and Implications for the Future

    Science.gov (United States)

    Finney, B.

    2002-12-01

    The response of Pacific salmon to future climatic change is uncertain, but will have large impacts on the economy, culture and ecology of the North Pacific Rim. Relationships between sockeye salmon populations and climatic change can be determined by analyzing sediment cores from lakes where sockeye return to spawn. Sockeye salmon return to their natal lake system to spawn and subsequently die following 2 - 3 years of feeding in the North Pacific Ocean. Sockeye salmon abundance can be reconstructed from stable nitrogen isotope analysis of lake sediment cores as returning sockeye transport significant quantities of N, relatively enriched in N-15, from the ocean to freshwater systems. Temporal changes in the input of salmon-derived N, and hence salmon abundance, can be quantified through downcore analysis of N isotopes. Reconstructions of sockeye salmon abundance from lakes in several regions of Alaska show similar temporal patterns, with variability occurring on decadal to millennial timescales. Over the past 2000 years, shifts in sockeye salmon abundance far exceed the historical decadal-scale variability. A decline occurred from about 100 BC - 800 AD, but salmon were consistently more abundant 1200 - 1900 AD. Declines since 1900 AD coincide with the period of extensive commercial fishing. Correspondence between these records and paleoclimatic data suggest that changes in salmon abundance are related to large scale climatic changes over the North Pacific. For example, the increase in salmon abundance c.a. 1200 AD corresponds to a period of glacial advance in southern Alaska, and a shift to drier conditions in western North America. Although the regionally coherent patterns in reconstructed salmon abundance are consistent with the hypothesis that climate is an important driver, the relationships do not always follow patterns observed in the 20th century. A main feature of recorded climate variability in this region is the alternation between multi-decade periods of

  5. Accumulation variability over a small area in east Dronning Maud Land, Antarctica, as determined from shallow firn cores and snow pits : some implications for ice-core records

    NARCIS (Netherlands)

    Karlof, Lars; Isaksson, Elisabeth; Winther, Jan-Gunnar; Gundestrup, Niels; Meijer, Harro A. J.; Mulvaney, Robert; Pourchet, Michel; Hofstede, Coen; Lappegard, Gaute; Pettersson, Rickard; Van den Broeke, Michiel; Van De Wal, Roderik S. W.

    2005-01-01

    We investigate and quantify the variability of snow accumulation rate around a medium-depth firn core (1160 m) drilled in east Dronning Maud Land, Antarctica (75 degrees 00'S, 15 degrees 00'E; 3470 m h.a.e. (ellipsoidal height)). We present accumulation data from five snow pits and five shallow (20

  6. Accumulation variability over a small area in east Dronning Maud Land, Antarctica, as determined from shallow firn cores and snow pits : some implications for ice-core records

    NARCIS (Netherlands)

    Karlof, Lars; Isaksson, Elisabeth; Winther, Jan-Gunnar; Gundestrup, Niels; Meijer, Harro A. J.; Mulvaney, Robert; Pourchet, Michel; Hofstede, Coen; Lappegard, Gaute; Pettersson, Rickard; Van den Broeke, Michiel; Van De Wal, Roderik S. W.

    2005-01-01

    We investigate and quantify the variability of snow accumulation rate around a medium-depth firn core (1160 m) drilled in east Dronning Maud Land, Antarctica (75 degrees 00'S, 15 degrees 00'E; 3470 m h.a.e. (ellipsoidal height)). We present accumulation data from five snow pits and five shallow (20

  7. Sub-annual Ice-Core Record of Major Ion and Heavy Metal Variability and Sources in the North Pacific Free Troposphere, Mt. Logan, Yukon, Canada

    Science.gov (United States)

    Osterberg, E. C.; Kurbatov, A. V.; Mayewski, P. A.; Kreutz, K. J.; Fisher, D.

    2005-12-01

    The Mt. Logan, Yukon, Canada summit plateau (PR Col; 5300 m.a.s.l.) ice core has been continuously sampled at high resolution (2-3 cm/sample) by a novel ice core melting system with discrete sampling, and analyzed for 8 major ions and 35 trace elements. Co-registered, sub-annual timeseries covering the past 500 years reveal seasonal aerosol fluctuations dominated by dust, with sea-salt contributing less than 5% of sulfate and calcium concentrations. Dating of the top 500 years of the record is by annual layer counting. Concentration spikes of sulfate greater than three times the standard deviation (60 ppb) above the mean (75 ppb) correspond in time with historical explosive volcanic eruptions. Sulfate spikes corresponding in time with large (VEI>4) historical Alaskan eruptions, including Katmai (1912) and St. Augustine (1986), are commonly associated with concentration and crustal enrichment factor spikes in lead, cadmium, antimony, copper, zinc, bismuth and thallium an order of magnitude above background (non-volcanic event) values. Sulfate spikes corresponding in time to large eruptions from distant volcanoes, including Agung (1963), do not show a corresponding rise in heavy metal concentrations. Apart from the periodic spikes in concentration, heavy metal timeseries largely mirror those of the major dust species (Al, Fe), but maintain significantly elevated crustal enrichment factors, probably due primarily to quiescent degassing of volcanoes. Such datasets are necessary to understand the cycling of heavy metals in the free troposphere, including the relative source strength of explosive eruptions vs. quiescent volcanic degassing, and the relative strength of natural vs. anthropogenic sources.

  8. The Influence of Aleutian Low Intensity on Trans-Pacific Lead Pollution Transport as Recorded in Two Saint Elias Ice Cores

    Science.gov (United States)

    Osterberg, E. C.; Kreutz, K. J.; Mayewski, P. A.; Fisher, D. A.; Wake, C. P.; Handley, M.

    2009-12-01

    The Aleutian Low (ALOW) is a semi-permanent low pressure center that dominates the wintertime climate of the North Pacific, and is an integral component of major ocean-atmosphere climate oscillations including the Pacific Decadal Oscillation and the extra-tropical response to the El Niño-Southern Oscillation. Previous research has suggested that the trans-Pacific transport of dust and pollution from Asia to the North Pacific is enhanced under conditions with a strong ALOW and strong Pacific High, increasing average mid-latitude westerly wind velocities. Here we investigate the influence of annual ALOW intensity fluctuations on the trans-Pacific transport of lead (Pb) pollution as recorded in ice cores collected from the Mt. Logan summit plateau (5300 m asl) and Eclipse Icefield (3017 m asl). These two ice core sites are well suited to investigate vertical gradients in climate and pollution because they are situated Mt. Logan summit and Eclipse Icefield receive significant trans-Pacific Pb pollution, the Mt. Logan summit Pb concentration is positively correlated with ALOW strength (r=0.40, pMt. Logan and Eclipse. Occluded cyclones are stratified by the warm front, with lower elevation sites like Eclipse situated in a cold-air zone sourced by a relatively clean local airmass from the Gulf of Alaska, whereas higher elevation sites like the Mt. Logan summit plateau are situated above the warm front where moisture and airmasses (and their pollutants) originate from more distant locations in the North Pacific and Asia. The relative proportion of local vs distant moisture feeding Eclipse and the Mt. Logan summit has previously been hypothesized to account for the observed stable water isotope “step” in the St. Elias range.

  9. Dating the 800 ka - long EPICA DC ice core by tuning the air content and δO2/N2 records on local summer insolation.

    Science.gov (United States)

    Raynaud, D.; Lipenkov, V.; Loutre, M.-F.; Landais, A.; Capron, E.

    2012-04-01

    A new method of dating the long glacial-interglacial ice core records has emerged during the last 10 years. It is based on properties measured on the air extracted from the ice that are used as proxies of local summer insolation. This dating method is referred to as "local orbital tuning dating". It's an almost absolute dating, providing we better understand the link between the influence of the local summer insolation on the snow grains at the surface and the measured properties in the ice, namely the content and the δO2/N2 ratio of the air enclosed in the ice. Changes in these two properties have already shown convincing correlations with orbitally forced local summer insolation on several Antarctic and Greenland long ice core records. Moreover, both δO2/N2 and air content have recently been measured for the first time on the same ice core (Vostok). The same methods of spectral analysis were applied on these records. The two experimentally independent local insolation proxies lead to orbital timescales that agree well together (within less than 1ka on average). We present here new air content (V) data obtained along the Antarctic EPICA DC ice cores. These data extent the existing record, which covers the last 430,000 years, to about 800,000 years, i.e. they add four glacial-interglacial cycles. The new record has a time resolution of 2,000 years on average. The spectral properties of the new 430 - 800 kyr V record are primarily obtained by continuous wavelet transform (CWT) analysis. It confirms and refines the results from the Blackman-Tukey (BT) and Multi-Taper Method (MTM analysis). The spectral signature of V is compared to its specific Integrated Summer Insolation (ISI) target and the time delay between the V signal and its ISI target is used to propose a V chronology for the oldest part of the record (800-430 kyr BP). The spectral signatures of V and the insolation targets will be compared between the 800 -430 ka BP period (this work) and the 430 - 0 ka

  10. Extending the High-Resolution Global Climate Record in Santa Barbara Basin: Developing a More Continuous Composite Section from Overlapping Cores

    Science.gov (United States)

    Behl, R. J.; Kennett, J. P.; Hill, T. M.; Pak, D.; Schimmelmann, A.; Cannariato, K. G.; Nicholson, C.; Sorlien, C. C.; Hopkins, S. E.; Team, S.

    2005-12-01

    More than thirty ~2 to 5m-long piston cores were recovered from an eroded, breached anticline on the Mid-Channel Trend of the Santa Barbara Basin (SBB). Precision placement of cores enabled us to build several composite stratigraphic sections of overlapping cores. This was accomplished by continuous shipboard evaluation and feedback between pre-existing and concurrently acquired high-resolution seismic data and immediate sedimentologic core analysis to determine subsequent core locations. Overlap was confirmed by correlated stratigraphic patterns of alternating laminated vs. massive intervals, gray flood layers, spectrophotometric and MST density/porosity data. These cores were acquired to provide a semi-continuous, composite paleoceanographic record of the Quaternary SBB and the California Margin that extends beyond the fertile ODP Site 893 core, to possibly as old as 450 to 600 ka, an age previously unreachable by conventional methods. Most cores were mantled by glauconitic sand or a thin carbonate hardground encrusted with sessile organisms, including solitary corals. Underlying the condensed Holocene sand or hardground deposits are alternating layers of Pleistocene laminated and massive/bioturbated sediment with minor sand and sandy clay layers. The style, continuity, and variability of laminated fabric and the nature of bedding contacts are similar to that observed at ODP Site 893 where glacial episodes were associated with oxygenated, bioturbated sediment and interglacial and interstadial sediment were associated with dysoxic, laminated sediment. Laminated sediment comprises 38% of the hemipelagic deposits which is nearly identical with the ratio of laminated to massive sediment over the past 160 ky at Site 893. By extrapolation, despite accumulating in a mobile, deforming, active margin basin, the earlier Pleistocene deposits seem to record similar behavior to the last 160 ky recorded at ODP Site 893. In some intervals, gray layers are thicker and more

  11. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders

    2014-01-01

    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  12. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders

    2014-01-01

    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  13. Upper Cretaceous chalk facies and depositional history recorded in the Mona-1 core, Mona Ridge, Danish North Sea

    Directory of Open Access Journals (Sweden)

    Finn Surlyk

    2011-12-01

    Full Text Available The 331 m long core from the Mona-1 well in the Danish North Sea spans almost the entire Upper Cretaceous Chalk Group but only about 10% of Late Cretaceous time is represented. The succession comprises 14 facies representing pelagic deposition, turbidity flow, and mass-transport processes, including mudflow, debris flow, and slumping. Pelagic deposits vary mainly in terms of the concentration of siliciclastic material, the trace-fossil assemblage, and the presence or ab¬sence of primary sedimentary structures. Pelagic sedimentation was probably punctuated by the deposition of thin turbidites, and the resultant deposits were thoroughly bioturbated if deposited during normal oxygenation at the sea floor. Periodic benthic dysoxia resulted in the preservation of primary structures, as represented by laminated chalk which consists of thin pelagic laminae alternating with thin turbidites. In addition to the thin turbidites in the laminated chalk, four dif¬ferent turbidite facies are interpreted as representing high- to low-energy flows. Clast-supported chalk conglomerates have previously not been differentiated from other turbidites, but are here interpreted to be directly related to the down-slope evolution of debris flows. Debris flows are rep¬resented by matrix-supported conglomerates, which form one of the most common facies in the succession. High-concentration, gravity-driven suspension flows passed into dilute visco-plastic flows during the final stages of deposition and resulted in the deposition of structureless chalks. Limited shear deformation produced distinct quasi-facies from which the precursor facies can be deduced, whereas intense or continued shear deformation produced a shear-banded quasi-facies from which the precursor facies cannot be deduced in all cases. A series of major slump packages (14–18 in total are interpreted, forming over 40% of the succession; debrites appear to be the most common precursor facies involved in

  14. Upper Cretaceous chalk facies and depositional history recorded in the Mona-1 core, Mona Ridge, Danish North Sea: Plate 1

    Directory of Open Access Journals (Sweden)

    Surlyk, Finn

    2011-12-01

    Full Text Available The 331 m long core from the Mona-1 well in the Danish North Sea spans almost the entire Upper Cretaceous Chalk Group but only about 10% of Late Cretaceous time is represented. The succession comprises 14 facies representing pelagic deposition, turbidity flow, and mass-transport processes, including mudflow, debris flow, and slumping. Pelagic deposits vary mainly in terms of the concentration of siliciclastic material, the trace-fossil assemblage, and the presence or ab¬sence of primary sedimentary structures. Pelagic sedimentation was probably punctuated by the deposition of thin turbidites, and the resultant deposits were thoroughly bioturbated if deposited during normal oxygenation at the sea floor. Periodic benthic dysoxia resulted in the preservation of primary structures, as represented by laminated chalk which consists of thin pelagic laminae alternating with thin turbidites. In addition to the thin turbidites in the laminated chalk, four dif¬ferent turbidite facies are interpreted as representing high- to low-energy flows. Clast-supported chalk conglomerates have previously not been differentiated from other turbidites, but are here interpreted to be directly related to the down-slope evolution of debris flows. Debris flows are rep¬resented by matrix-supported conglomerates, which form one of the most common facies in the succession. High-concentration, gravity-driven suspension flows passed into dilute visco-plastic flows during the final stages of deposition and resulted in the deposition of structureless chalks. Limited shear deformation produced distinct quasi-facies from which the precursor facies can be deduced, whereas intense or continued shear deformation produced a shear-banded quasi-facies from which the precursor facies cannot be deduced in all cases. A series of major slump packages (14–18 in total are interpreted, forming over 40% of the succession; debrites appear to be the most common precursor facies involved in

  15. Prediction of cardiac death : an epidemiological study on the prognostic significance of 24-hour ECG-recording

    NARCIS (Netherlands)

    J.P. Velema (Johan)

    1982-01-01

    textabstractSince the introduction of the string galvanometer by Einthoven (1901), various instruments have been developed (a technical review is given by Dunn & Rahm, 1950) to record the so-called electrocardiogram (ECG). Physical activity, changes in position and certain bodily functions such as d

  16. Millennial and sub-millennial scale climatic variations recorded in polar ice cores over the last glacial period

    National Research Council Canada - National Science Library

    Capron, E; Landais, A; Chappellaz, J; Schilt, A; Buiron, D; Dahl-Jensen, D; Johnsen, S. J; Jouzel, J; Lemieux-Dudon, B; Loulergue, L; Leuenberger, M; Masson-Delmotte, V; Meyer, H; Oerter, H; Stenni, B

    2010-01-01

    Since its discovery in Greenland ice cores, the millennial scale climatic variability of the last glacial period has been increasingly documented at all latitudes with studies focusing mainly on Marine Isotopic Stage 3 (MIS 3...

  17. Tibetan Plateau Geladaindong black carbon ice core record (1843–1982: Recent increases due to higher emissions and lower snow accumulation

    Directory of Open Access Journals (Sweden)

    Jenkins Matthew

    2016-09-01

    Full Text Available Black carbon (BC deposited on snow and glacier surfaces can reduce albedo and lead to accelerated melt. An ice core recovered from Guoqu glacier on Mt. Geladaindong and analyzed using a Single Particle Soot Photometer (SP2 provides the first long-term (1843–1982 record of BC from the central Tibetan Plateau. Post 1940 the record is characterized by an increased occurrence of years with above average BC, and the highest BC values of the record. The BC increase in recent decades is likely caused by a combination of increased emissions from regional BC sources, and a reduction in snow accumulation. Guoqu glacier has received no net ice accumulation since the 1980s, and is a potential example of a glacier where an increase in the equilibrium line altitude is exposing buried high impurity layers. That BC concentrations in the uppermost layers of the Geladaindong ice core are not substantially higher relative to deeper in the ice core suggests that some of the BC that must have been deposited on Guoqu glacier via wet or dry deposition between 1983 and 2005 has been removed from the surface of the glacier, potentially via supraglacial or englacial meltwater.

  18. Evidence for in-situ metabolic activity in ice sheets based on anomalous trace gas records from the Vostok and other ice cores

    Science.gov (United States)

    Sowers, T.

    2003-04-01

    Measurements of trace gas species in ice cores are the primary means for reconstructing the composition of the atmosphere. The longest such record comes from the Vostok core taken from the central portion of the East Antarctic ice sheet [Petit et al., 1999]. In general, the trace gas records from Vostok are utilized as the reference signal when correlating trace gas measurements from other ice cores. The underlying assumption implicit in such endeavors is that the bubbles recovered from the ice cores record the composition of the atmosphere at the time the bubbles were formed. Another implicit assumption is that the composition of the bubbles has not been compromised by the extremely long storage periods within the ice sheet. While there is ample evidence that certain trace gas records (e.g. CO2 and CH4) have probably not been compromised, anomalous nitrous oxide (N2O) measurements from the penultimate glacial termination at Vostok are consistent with in-situ (N2O) production [Sowers, 2001]. In general, trace gas measurements from high altitude tropical/temperate glaciers are higher than expected based on contemporaneous measurements from polar cores. Measurements spanning the last 25kyr from the Sajama ice core from central Bolivia (18oS, 69oW, 6542masl), for example, were 1X-5X higher than contemporaneous values recorded in polar ice cores [Campen et al., 2003]. While other physical factors (like temperature/melting) may contribute to the elevated trace gas levels at these sites, the most likely explanation involves the accumulation of in-situ metabolic trace gas byproducts. Stable isotope measurements provide independent information for assessing the origin of the elevated trace gas levels in select samples. For the penultimate glacial termination at Vostok, the anomalous (N2O) values carry high δ15Nbulk and low δ18Obulk values that would be predicted if the added (N2O) was associated with in-situ nitrification. At Sajama, low δ13CH4 values observed during

  19. Exploring the possibility to detect recent temporal changes in highly disturbed sedimentary records through sampling repetitions and core comparisons of porosity and sand content.

    Science.gov (United States)

    Giuliani, S; Bellucci, L G; Romano, S; Piazza, R; Turetta, C; Vecchiato, M; Nhon, D H; Frignani, M

    2015-07-01

    Dating of sediment cores in dynamic environments (such as tropical coastal lagoons) is often impossible to achieve, due to the difficulty to recover continuous and undisturbed records. Detailed temporal definition of environmental changes cannot be assured, but there is the possibility that information retained in such sediments can still provide useful insights on local or large-scale sedimentary dynamics, when a specific strategy is adopted. This latter consists in repeated core samplings at the same location and in the comparison of core profiles for basic and easily measurable parameters (porosity and sand content). This approach was tested on sediment cores, collected repeatedly during the period 2005-2010, at the same site of the Thi Nai Lagoon (central Vietnam). The proposed procedure was able to evidence the impact on lagoon sediments of activities linked to the construction of industrial settlements in the area, with dredging removing a consistent sediment layer from 2005 to 2008 and waste dumping providing additional sediment input in the following period. Simple statistic confirmed this scenario, together with core profiles of PCBs, As, Cd, Pb, and Zn. The procedure represents a simple tool to study coastal dynamics in places where the level of accuracy of traditional sediment radiodating cannot be reached. Several ameliorations are suggested in order to help developing the monitoring of sedimentary processes in poorly studied areas.

  20. Using beryllium-10 to test the validity of past accumulation rate reconstruction from water isotope records in East Antarctic ice cores

    Directory of Open Access Journals (Sweden)

    A. Cauquoin

    2014-08-01

    Full Text Available Ice cores are exceptional archives which allow us to reconstruct a wealth of climatic parameters as well as past atmospheric composition over the last 800 ka in Antarctica. Inferring the variations of past accumulation rate in polar regions is essential both for documenting past climate and for ice core chronology. On the East Antarctic plateau, the accumulation rate is so small that annual layers cannot be identified and accumulation rate is mainly deduced from the water isotopic composition assuming constant temporal relationships between temperature, water isotopic composition and accumulation rate. Such assumption leads to large uncertainties on the reconstructed past accumulation rate. Here, we use high resolution beryllium-10 (10Be as an alternative tool for inferring past accumulation rate for the EPICA Dome C ice core, in East Antarctica. We present a high resolution 10Be record covering a full climatic cycle over the period 269 to 355 kyr BP from MIS 9 to MIS 10 (Marine Isotope Stages. After correcting 10Be for the estimated effect of the paleomagnetic field, we deduce that the classical estimation of accumulation rate variations from records of water isotopes agrees, with a possible underestimation of 16%, with the uncertainty on the temperature reconstruction from water isotopes in Antarctic ice cores. This is within their uncertainty of −10 to +30%. Finally, we show that the relationship between temperature and accumulation rate is comparable when using ice core data and results from several AGCM simulations run on glacial–interglacial conditions despite a larger spread in model outputs. These results indicate that the thermodynamic law linking moisture content in the air and temperature, as implemented in the different models, leads to realistic results even in polar regions, at the end of the water distillation trajectory.

  1. [Recording cervical and ocular vestibular evoked myogenic potentials. Part 2: influencing factors, evaluation of findings and clinical significance].

    Science.gov (United States)

    Walther, L E; Hörmann, K; Pfaar, O

    2010-11-01

    VEMP measurements are subject to various influencing factors: patient age, threshold, sound intensity and frequency. Using air (AC) and bone conduction (BC) the vestibular receptors and afferents of the otolith organs can be activated to varying degrees. Recordings of cervical (cVEMP) and ocular VEMP (oVEMP) are clinically possible. AC-cVEMP are primarily an indicator of the sacculocollic reflex pathway. Together with findings on the vestibuloocular reflex (VOR) and complimentary otolith tests, VEMP enable otolith function analysis of each side separately. In addition, the distinction between combined or isolated canal and otolith dysfunction in terms of subtyping and patterns of damage in mono- and bilateral disorders, such as vestibular neuritis or bilateral vestibulopathy, is possible. Moreover, VEMP is relevant in terms of prognostic and therapeutic considerations as well as expert assessments.

  2. Pelagic records from the Equatorial Ninetyeast Ridge and significant environmental events during the past 3.5 Ma

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper presents pelagic records of planktic foraminifera,as well as data of stable isotope stratigraphy and carbonate stratigraphy since 3.5 Ma B.P.from site ODP758 in the Ninetyeast Ridge of the Indian Ocean.Based on these data,manifestations and related mechanisms of major tectonic and environmental events such as the rapid uplift of the Himalaya Mountains,"middle Pleistocene climatic transition" and""mid-Brunhes dissolution event"in the region are discussed.According to the analysis and comparison of various indices and changes in terms of foraminifera assemblage,paleotemperature,paleosalinity and themocline from site ODP758,the authors deduce that the paleoclimatic changes might correlate with the mid-Pleistocene transition at 1.4-1.7 Ma B.P.The changes of CaCO3,mass accumulation rates (MAR) of CaCO3 and non- CaCO3 MAR indicate that the loaded terrigenous sediments increased at 1.7 Ma,which is in agreement with the uplift history of the Qinghai-Tibet plateau as shown by the available data.The last two changes coincide with the uplift of the Qinghai-Tibet plateau,hence they are called"Qinghai-Tibet movement" (1.7 Ma),and the"Kunlun-Yellow River movement"(1.2-0.6 Ma).The changes of the CaCO3 content,coarse fraction (>150 μm) content and planktonic foraminifera biostratigraphy show that strong dissolution of abyssal CaCO3 occurred in the study region during 0.5-0.4 Ma.The event was consistent with the "mid-Brunhes dissolution event"in the sedimentary records of the Atlantic Ocean,Pacific Ocean,Indian Ocean and Nansha sea area of the South China Sea.

  3. Long-distance relationship between large-scale tropical SSTs and ice core-derived oxygen isotopic records in the Third Pole Region

    Science.gov (United States)

    Thompson, L. G.; Yao, T.; Mosley-Thompson, E. S.; Lin, P.

    2012-12-01

    The tropical hydrological cycle is a key factor coupling isotopic records from ice core, speleothem and lake records with tropical SSTs and the vertical amplification of temperature in the Tropics. Stable isotopic ratios, particularly of oxygen, preserved in glacier ice provide high resolution records of climate changes over long time periods. In polar ice sheets the isotopic signal is driven primarily by temperature while in low-latitudes it depends on a variety of hydrologic and thermal influences in the broad geographic region that supplies moisture to the mountain glaciers. The strong correlation between ice core-derived isotopic records throughout the low- and mid-latitudes and tropical SSTs likely reflects the dominance of tropical evaporation in the flux of water vapor to the atmosphere and provides a possible explanation for the large-scale isotopic links among low- and mid-latitude paleoclimate records. Many low- to mid-latitude ice fields provide continuous, annually-resolved proxy records of climatic and environmental variability recorded by many preserved and measurable parameters including oxygen and hydrogen isotopic ratios and net mass balance (accumulation). These records present an opportunity to examine the nature of climate variability in these regions in greater detail and to extract new information about long-distance relationships in the climate system. Understanding these relationships is essential for proper interpretation of the isotopic records archived in glaciers, lakes, speleothems and other paleo-archives in the Third Pole (TP) Region. Here we compare high resolution records from Dasuopu Glacier in the Himalaya, a speleothem record from Wanxiang Cave in Gansu Province on the TP and the annually resolved ice core records from the Quelccaya Ice Cap in the tropical Andes of South America. The purpose is to explore the role of long-distance processes in determining the isotopic composition of paleo archives on the TP. Running correlations

  4. Interannual to decadal scale North Pacific climate dynamics during the last millennium from Eclipse Icefield (St. Elias Mountains) ice core stable isotope records

    Science.gov (United States)

    Kreutz, K. J.; Wake, C.; Yalcin, K.; Vogan, N.; Introne, D.; Fisher, D.; Osterberg, E.

    2006-12-01

    A 345 meter ice core recovered from the St. Elias Mountains, Yukon Territory, Canada during 2002 has been continuously analyzed for stable hydrogen isotopes (deltaD), and is used to interpret changes in the North Pacfic hydrologic cycle and climate variability over the past 1000 years. Given the high annual snow accumulation rate at the site (1.5 meters/year), the record is high resolution (subannual) and annually dated to 1450 AD, and dated with ice flow models prior to 1450 AD. Five-year averaged isotope data over the past millennium display a classic Little Ice Age (LIA)/Medieval Climate Anomaly (MCA) pattern; that is, lower isotope ratios during the LIA, and higher isotope ratios during the MCA. Using the simple isotope/temperature relationship typically applied to ice core data, the Eclipse record may indicate lower regional temperatures and enhanced temperature variability during the period 1250 to 1700 AD. However, isotope data from an ice core recovered near the summit of Mt. Logan is clearly related to different hydrologic regimes. Regardless of the scaling used on the Eclipse isotope data, a distinct drop in isotope ratio occurs just prior to 1200AD, and may correspond with changes observed in tropical coral records. We suggest that fundamental changes in teleconnection and/or ENSO/PDO dynamics between the high and low latitudes in the Pacific may be responsible for the 13th century event. Based on the 1000-year record at 5-year resolution, as well as annual isotope data for the past 550 years, the 20th century is not anomalous with respect to previous time periods.

  5. A record of the upper Olduvai geomagnetic polarity transition from a sediment core in southern Yokohama City, Pacific side of central Japan

    Science.gov (United States)

    Kusu, Chie; Okada, Makoto; Nozaki, Atsushi; Majima, Ryuichi; Wada, Hideki

    2016-12-01

    A detailed paleomagnetic record of the upper Olduvai polarity transition was obtained from a 106.72 m-long sediment core drilled in southern Yokohama City, located on the northern Miura Peninsula, on the Pacific side of central Japan. The core spans the upper part of the Nojima Formation and the lowermost part of the Ofuna Formation, both of which correspond to the middle Kazusa Group (Lower Pleistocene forearc basin fill). The record was reconstructed using discrete specimens taken throughout mudstone and/or sandy mudstone sequences in the Nojima Formation. In this record, the virtual geomagnetic pole (VGP) fluctuation accompanying the polarity transition was determined to occur between depths of 66.99 and 63.60 m. These depths have been dated at 1784.4 and 1779.9 ka, respectively, and the duration of the polarity transition is estimated to be 4.5 kyr using an age model based on a δ18O record from that core. The VGP paths during the transition do not appear to show any preferred longitudinal bands. However, the VGP positions cluster in five areas: (A) eastern Asia near Japan, (B) the Middle East, (C) eastern North America (North Atlantic), (D) off southern Australasia, and (E) the southern South Atlantic off South Africa. The primary locations of the observed VGP clusters coincide with the areas on the Earth's surface that possess a strong downward flux of the vertical component of the present geomagnetic non-axial dipole field. The relative paleointensity rapidly decreased approximately 1 kyr before the beginning of the polarity transition and gradually recovered to its initial level in 12 kyr.

  6. Ice Cores

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature, precipitation, atmospheric trace gases, and other aspects of climate and environment derived from ice cores drilled on glaciers and ice...

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

    Science.gov (United States)

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

    2014-12-01

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

  8. Record high-speed short-range transmission over 1 mm core diameter POF employing DMT modulation.

    Science.gov (United States)

    Yang, H; Lee, S C J; Okonkwo, C M; Abraha, S T; van den Boom, H P A; Breyer, F; Randel, S; Koonen, A M J; Tangdiongga, E

    2010-03-01

    We report multigigabit/second transmission capacity in 1 mm core diameter graded index plastic optical fiber (POF) exploiting off-the-shelf low-cost components and discrete multitone (DMT) modulation. Transmission capacities of 10.1 Gbits/s x 15 m and 12.7 Gbits/s x 3 m are achieved for average bit-error rates less than 10(-3).

  9. Recovering Paleo-Records from Antarctic Ice-Cores by Coupling a Continuous Melting Device and Fast Ion Chromatography.

    Science.gov (United States)

    Severi, Mirko; Becagli, Silvia; Traversi, Rita; Udisti, Roberto

    2015-11-17

    Recently, the increasing interest in the understanding of global climatic changes and on natural processes related to climate yielded the development and improvement of new analytical methods for the analysis of environmental samples. The determination of trace chemical species is a useful tool in paleoclimatology, and the techniques for the analysis of ice cores have evolved during the past few years from laborious measurements on discrete samples to continuous techniques allowing higher temporal resolution, higher sensitivity and, above all, higher throughput. Two fast ion chromatographic (FIC) methods are presented. The first method was able to measure Cl(-), NO3(-) and SO4(2-) in a melter-based continuous flow system separating the three analytes in just 1 min. The second method (called Ultra-FIC) was able to perform a single chromatographic analysis in just 30 s and the resulting sampling resolution was 1.0 cm with a typical melting rate of 4.0 cm min(-1). Both methods combine the accuracy, precision, and low detection limits of ion chromatography with the enhanced speed and high depth resolution of continuous melting systems. Both methods have been tested and validated with the analysis of several hundred meters of different ice cores. In particular, the Ultra-FIC method was used to reconstruct the high-resolution SO4(2-) profile of the last 10,000 years for the EDML ice core, allowing the counting of the annual layers, which represents a key point in dating these kind of natural archives.

  10. Aligning MIS5 proxy records from Lake Ohrid (FYROM) with independently dated Mediterranean archives: implications for core chronology

    Science.gov (United States)

    Zanchetta, G.; Regattieri, E.; Giaccio, B.; Wagner, B.; Sulpizio, R.; Francke, A.; Vogel, L. H.; Sadori, L.; Masi, A.; Sinopoli, G.; Lacey, J. H.; Leng, M. L.; Leicher, N.

    2015-10-01

    The DEEP site sediment sequence obtained during the ICDP SCOPSCO project at Lake Ohrid was dated using tephrostratigraphic information, cyclostratigraphy, and orbital tuning through marine isotope record. Although this approach is suitable for the generation of a general chronological framework of the long succession, it is insufficient to resolve more detailed paleoclimatological questions, such as leads and lags of climate events between marine and terrestrial records or between different regions. In this paper, we demonstrate how the use of different tie points can affect cyclostratigraphy and orbital tuning for the period between ca. 140 and 70 ka and how the results can be correlated with directly/indirectly radiometrically-dated Mediterranean marine and continental proxy records. The alternative age model obtained shows consistent differences with that proposed by Francke et al. (2015) for the same interval, in particular at the level of the MIS6-5e transition. According to this age model, different proxies from the DEEP site sediment record support an increase of temperatures between glacial to interglacial conditions, which is almost synchronous with a rapid increase in sea surface temperature observed in the western Mediterranean. The results show how important a detailed study of independent chronological tie points is for synchronizing different records and to highlight asynchronisms of climate events.

  11. Three magnetic reversals recorded in an 80-m organic-rich core from a sinkhole east of Tampa, FL

    Energy Technology Data Exchange (ETDEWEB)

    McCartan, L.; Rubin, M. (Geological Survey, Reston, VA (United States)); Liddicoat, J.C. (Barnard Coll, New York, NY (United States)); Bond, P.A.; Osmond, J.K. (Florida State Univ., Tallahassee, FL (United States))

    1994-03-01

    Preliminary analysis of a continuous 80-m core from a phosphate mines at Bartow, Fla., indicates as many as three magnetically reversed and five normal sections and five upward-fining depositional sequences. The paleomagnetic data are based on analysis of 16 samples; 100 additional samples have been taken for more detailed analysis. The authors estimate the maximum age to be 1.1--2.6 Ma. The core is composed of massive to faintly laminated beds of black to dark-brown, organic-rich, fine quartz sand and silt, kaolinitic and organic clay, and peat, Only the top meter is within the 40 Ka range of [sup 14]C; a sample at 8.5 m yielded an age estimate close to 350,000 years, the limit of the open-system U/Th dating technique. Rates of deposition are 2--7.5 cm/1,000 years, which is much slower than rates in late Quaternary lakes elsewhere in Florida. There is no clear relation between the magnetic stratigraphy and the depositional stratigraphy. The authors assume that most of the sand was derived from dissolved limestone around the sinkhole, but some of the sand as well as the silt and clay may be windborne. Textural variations may be coincident with differences in rainfall, and this concept will be investigated through pollen analysis of approximately 800 samples. The one sample examined so far is from the bottom of the core, and it has an equivocal biostratigraphic age. The high grass pollen content indicates a drier climate than at present; it is from a long interval of peat with sand, which is typically windborne in dry climates.

  12. The orbital scale evolution of regional climate recorded in a long sediment core from Heqing,China

    Institute of Scientific and Technical Information of China (English)

    SHEN Ji; XIAO HaiFeng; WANG SuMin; AN ZhiSheng; QIANG XiaoKe; XIAO XiaYun

    2007-01-01

    Based on the analysis of carbonate content and loss on ignition for a long sediment core (737 m in length) drilled in Heqing,the orbital scale evolution of the Southwest Monsoon is revealed,by using overlapped spectral analysis and filter methods. It is shown that the obliquity cycle and precession cycle are the key factors for the Southwest Monsoon evolution and that the change of the global ice volume and the uplift of the Qinghai-Tibetan Plateau also impose great influences on it.

  13. Decrease trend of dust event frequency over the past 200 years recorded in the Malan ice core from the northern Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG Ninglian

    2005-01-01

    By analyses of the dust layers in the Malan ice core from the northern Tibetan Plateau, it was found that dirty ratio in this core might be a good proxy for dust event frequency. The variations in the dirty ratio displayed a decrease trend over the past 200 years, which implies that dust events became less frequent during the study period. The decrease trend in the variations in dust event frequency might be caused mostly by the natural processes, including increasing precipitation and weakening westerly which might be related with global warming. Furthermore, significant negative correlation was found between the dirty ratio and δ18O in the Malan ice core. This is highly important for studying the effect of atmospheric dust on climate change.

  14. Record of Volcanism Since 7000 B.C. from the GISP2 Greenland Ice Core and Implications for the Volcano-Climate System.

    Science.gov (United States)

    Zielinski, G A; Mayewski, P A; Meeker, L D; Whitlow, S; Twickler, M S; Morrison, M; Meese, D A; Gow, A J; Alley, R B

    1994-05-13

    Sulfate concentrations from continuous biyearly sampling of the GISP2 Greenland ice core provide a record of potential climate-forcing volcanism since 7000 B.C. Although 85 percent of the events recorded over the last 2000 years were matched to documented volcanic eruptions, only about 30 percent of the events from 1 to 7000 B.C. were matched to such events. Several historic eruptions may have been greater sulfur producers than previously thought. There are three times as many events from 5000 to 7000 B.C. as over the last two millennia with sulfate deposition equal to or up to five times that of the largest known historical eruptions. This increased volcanism in the early Holocene may have contributed to climatic cooling.

  15. Deep water gravity core from the Marsili Basin (Tyrrhenian Sea) records Pleistocenic Holocenic explosive events and instability of the Aeolian Archipelago, (Italy)

    Science.gov (United States)

    Di Roberto, A.; Rosi, M.; Bertagnini, A.; Marani, M. P.; Gamberi, F.; Del Principe, A.

    2008-10-01

    A 4.8 m long gravity core was recovered on a relative topographic high in the northern part of the Marsili Basin (southern Tyrrhenian Sea) at a water depth of 3200 m. The core was taken in order to decipher the sedimentary record of the past volcanic events of the nearby Aeolian arc. A succession of thin (2 cm to 5 cm thick) fine-grained turbidites, mainly of volcaniclastic origin, topped by hemipelagic mud layers and a number of primary tephra layers were recovered by the core. The most prominent turbidite occurs in the lower part of the core at 385 cm. It consists of a 20 cm-thick, thinning-upward, pebble to sand-sized bed. Grain-size analysis and component compositions in the 0.063-0.250 mm size fractions were determined on thirty samples taken from primary tephra beds and the silty-sandy basal part of the volcaniclastic turbidite units. SEM scans and glass fraction chemical analyses were successively carried out on a selection of 17 samples. To aid source correlation and comparison, sub-aerial tephras of the Lower Pollara (Salina, 24 ± 3.6 ka), Gabellotto-Fiumebianco (Lipari, 8.5 or 11.5 ka), Monte Pilato (Lipari, 749 or 580 AD) and Secche di Lazzaro (Stromboli, ~ 5 ka) eruptions were also analyzed with the same procedure. Primary tephra respectively belonging to the eruptions of Lower Pollara, Gabellotto-Fiumebianco and Vesuvius (AP eruptions 3.5 ka-79 AD) were identified in the core at the expected relative stratigraphic depths. Two turbidite beds composed of monogenic glass shards were also identified and interpreted as the remobilisation of primary tephras of Secche di Lazzaro (Stromboli, 5 ka) and Pilato (Lipari, 580 or 749 AD). Tephrochronology results indicate that the cored sequence formed in the last 30 ka suggesting an average sedimentation rate of 0.15-0.17 mm/y. The thick pebbly sandy turbidite unit in the lower part of the core has component and glass composition compatible with the Lower Pollara volcanic sequence of Salina Island. In view of the

  16. Optical trapping of nanoparticles with significantly reduced laser powers by using counter-propagating beams (Presentation Recording)

    Science.gov (United States)

    Zhao, Chenglong; LeBrun, Thomas W.

    2015-08-01

    Gold nanoparticles (GNP) have wide applications ranging from nanoscale heating to cancer therapy and biological sensing. Optical trapping of GNPs as small as 18 nm has been successfully achieved with laser power as high as 855 mW, but such high powers can damage trapped particles (particularly biological systems) as well heat the fluid, thereby destabilizing the trap. In this article, we show that counter propagating beams (CPB) can successfully trap GNP with laser powers reduced by a factor of 50 compared to that with a single beam. The trapping position of a GNP inside a counter-propagating trap can be easily modulated by either changing the relative power or position of the two beams. Furthermore, we find that under our conditions while a single-beam most stably traps a single particle, the counter-propagating beam can more easily trap multiple particles. This (CPB) trap is compatible with the feedback control system we recently demonstrated to increase the trapping lifetimes of nanoparticles by more than an order of magnitude. Thus, we believe that the future development of advanced trapping techniques combining counter-propagating traps together with control systems should significantly extend the capabilities of optical manipulation of nanoparticles for prototyping and testing 3D nanodevices and bio-sensing.

  17. Historical lead isotope record of a sediment core from the Derwent River (Tasmania, Australia): a multiple source environment.

    Science.gov (United States)

    Townsend, Ashley T; Seen, Andrew J

    2012-05-01

    A 105 cm sediment core from the Derwent River (Tasmania, Australia) was collected in 2004 and was characterised considering both physical (loss on ignition at 550 °C and grain size) and chemical (Fe, Cu, Zn, Cd and Pb concentrations, Pb isotope ratios and (210)Pb dating) properties. The core was analysed to (i) investigate the historical profiles of some important elements associated with the Risdon zinc refinery adjacent to the Derwent River, (ii) determine Pb isotopic signatures of sediment samples, and (iii) assess the veracity of Pb isotope ratios as indicators of contaminant Pb input. Extractable metal concentrations were (all values as mgkg(-1), non-normalised for grain size) Fe: 20,000-35,000, Zn: 42-4500, Pb: 5-1090, Cu: 13-141, and Cd: 1-31; with a close correlation between Cu, Zn, Cd and Pb. Metal enrichment factors (normalised to Al) were Pb: 0.9-144, Zn: 0.8-93, Cd: 0.8-30, Cu: 0.8-8.9 and Fe: 0.9-1.3, confirming anthropogenic contributions of Cu, Zn, Pb and Cd to the sediments. The onset of metal contamination above background levels occurred at a depth between 43 and 49 cm, with maximum concentrations noted near 20 cm for Cu, Zn, Cd and Pb. Lead isotope ratios were determined in sediments using sector field ICP-MS, and were found to be 36.5-38.8, 16.5-18.7 and 1.07-1.20 for (208)Pb/(204)Pb, (206)Pb/(204)Pb and (206)Pb/(207)Pb ratios, respectively. Major Australian ores processed at the refinery over the previous ~90 years include those from Broken Hill, Rosebery, Mt Isa, Elura, Hellyer and Century deposits. Anthropogenic impact by Pb with Broken Hill type isotopic ratio was initially evident in the core at 43-49 cm. The introduction of Rosebery and Elura ores to the refinery was also clearly noted. Pb isotope ratios further highlight that the Derwent River has been exposed to a greater impact by anthropogenic Pb in comparison to other major Tasmanian rivers, namely the Huon and Tamar.

  18. An 800-year record of atmospheric As, Mo, Sn, and Sb in central Asia in high-altitude ice cores from Mt. Qomolangma (Everest), Himalayas.

    Science.gov (United States)

    Hong, Sungmin; Lee, Khanghyun; Hou, Shugui; Hur, Soon Do; Ren, Jiawen; Burn, Laurie J; Rosman, Kevin J R; Barbante, Carlo; Boutron, Claude F

    2009-11-01

    As, Mo, Sn, and Sb have been determined by inductively coupled plasma sector field mass spectrometry (ICP-SFMS) in 143 depth intervals of high-altitude ice cores from Mt. Everest, covering an 800-year time period from 1205 to 2002 AD. The results clearly demonstrate the long-term historical record of atmospheric transport and deposition of As, Mo, Sn, and Sb that has prevailed at high altitudes in the central Himalayas. Natural contributions, mainly from mineral dust, have dominated the atmospheric cycles of As, Mo, Sn, and to some extent Sb during the 700 years prior to the 20th century. Compared to those of the pre-1900 period, pronounced increases of both concentrations and crustal enrichment factors are observed since the 1970s, with the highest increase factor for Sn and the lowest for As. Such increases are attributed to anthropogenic emissions of these elements, largely from stationary fossil fuel combustion and nonferrous metals production, particularly in India. Our central Himalayan ice core record provides an explicit recognition of rising atmospheric As, Mo, Sn, and Sb pollution in response to rapid economic growth in central Asia.

  19. Millennial and sub-millennial scale climatic variations recorded in polar ice cores over the last glacial period

    DEFF Research Database (Denmark)

    Capron, E.; Landais, A.; Chappellaz, J.

    2010-01-01

    Since its discovery in Greenland ice cores, the millennial scale climatic variability of the last glacial period has been increasingly documented at all latitudes with studies focusing mainly on Marine Isotopic Stage 3 (MIS 3; 28–60 thousand of years before present, hereafter ka) and characterized...... a succession of abrupt events associated with long Greenland InterStadial phases (GIS) enabling us to highlight a sub-millennial scale climatic variability depicted by (i) short-lived and abrupt warming events preceding some GIS (precursor-type events) and (ii) abrupt warming events at the end of some GIS...... (rebound-type events). The occurrence of these sub-millennial scale events is suggested to be driven by the insolation at high northern latitudes together with the internal forcing of ice sheets. Thanks to a recent NorthGRIP-EPICA Dronning Maud Land (EDML) common timescale over MIS 5, the bipolar sequence...

  20. Historical lead isotope record of a sediment core from the Derwent River (Tasmania, Australia): A multiple source environment

    Energy Technology Data Exchange (ETDEWEB)

    Townsend, Ashley T., E-mail: Ashley.Townsend@utas.edu.au [Central Science Laboratory, University of Tasmania, Private Bag 74, Hobart, Tasmania 7001 (Australia); Seen, Andrew J. [School of Chemistry, University of Tasmania, Locked Bag 1371, Launceston, Tasmania 7250 (Australia)

    2012-05-01

    A 105 cm sediment core from the Derwent River (Tasmania, Australia) was collected in 2004 and was characterised considering both physical (loss on ignition at 550 Degree-Sign C and grain size) and chemical (Fe, Cu, Zn, Cd and Pb concentrations, Pb isotope ratios and {sup 210}Pb dating) properties. The core was analysed to (i) investigate the historical profiles of some important elements associated with the Risdon zinc refinery adjacent to the Derwent River, (ii) determine Pb isotopic signatures of sediment samples, and (iii) assess the veracity of Pb isotope ratios as indicators of contaminant Pb input. Extractable metal concentrations were (all values as mg kg{sup -1}, non-normalised for grain size) Fe: 20,000-35,000, Zn: 42-4500, Pb: 5-1090, Cu: 13-141, and Cd: 1-31; with a close correlation between Cu, Zn, Cd and Pb. Metal enrichment factors (normalised to Al) were Pb: 0.9-144, Zn: 0.8-93, Cd: 0.8-30, Cu: 0.8-8.9 and Fe: 0.9-1.3, confirming anthropogenic contributions of Cu, Zn, Pb and Cd to the sediments. The onset of metal contamination above background levels occurred at a depth between 43 and 49 cm, with maximum concentrations noted near 20 cm for Cu, Zn, Cd and Pb. Lead isotope ratios were determined in sediments using sector field ICP-MS, and were found to be 36.5-38.8, 16.5-18.7 and 1.07-1.20 for {sup 208}Pb/{sup 204}Pb, {sup 206}Pb/{sup 204}Pb and {sup 206}Pb/{sup 207}Pb ratios, respectively. Major Australian ores processed at the refinery over the previous {approx} 90 years include those from Broken Hill, Rosebery, Mt Isa, Elura, Hellyer and Century deposits. Anthropogenic impact by Pb with Broken Hill type isotopic ratio was initially evident in the core at 43-49 cm. The introduction of Rosebery and Elura ores to the refinery was also clearly noted. Pb isotope ratios further highlight that the Derwent River has been exposed to a greater impact by anthropogenic Pb in comparison to other major Tasmanian rivers, namely the Huon and Tamar. - Highlights

  1. Tephra records from abyssal sediments off western Sumatra in recent 135 ka:evidence from Core IR-GC1

    Institute of Scientific and Technical Information of China (English)

    QIU Zhongyan; HAN Xiqiu; JIN Xianglong; WANG Yejian; ZHU Jihao

    2014-01-01

    Three volcanic ash layers were identified in a deep-sea Core IR-GC1 from the north-eastern Indian Ocean, adjacent to western Indonesian arc. They were dominated by glass shards with minor mineral crystals, such as plagioclase, biotite, and hornblende. According to the morphology and major element compositions of the representative glass shards, combined with theδ18O-based age, it is suggested that ash Layer A is cor-related to the youngest Toba tuff (YTT), Layer B is supposed to be associated with a new eruption of Toba caldera in an age of 98 to 100 ka. Ash Layer C is different the geochemistry characteristics than those of Layer A and Layer B, suggesting that Layer C was not originated from Toba but registered another volcanic erup-tion event.

  2. Climatic records in a firn core from an Alpine temperate glacier on Mt. Yulong, southeastern part of the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    He Yuanqing; Yao Tandong; Cheng Guodong; Yang Meixue

    2001-01-01

    @@ Mt. Yulong is the southernmost glacier-covered area in Eurasia, including China. There are 19 sub-tropical temperate glaciers on the mountain, controlled by the southwestern monsoon climate. In the summer of 1999,a firn core, 10.10 m long, extending down to glacier ice,was recovered in the accumulation area of the largest glacier, Baishui No. 1. Periodic variations of climatic signals above 7.8 m depth were apparent, and net accumulation off our years was identified by the annual oscillations of isotopic and ionic composition. The boundaries of annual accumulation were confirmed by higher values of electrical conductivity and pH, and by dirty refreezing ice layers at the levels of summer surfaces.

  3. Climate Driven Changes in the Formation Pathways of Atmospheric Sulfate: A Comparison from Bipolar Ice Core Records

    Science.gov (United States)

    Geng, L.; Alexander, B.

    2013-12-01

    Atmospheric sulfate aerosol affects radiative forcing of the atmosphere and thus climate. The formation pathways of sulfate, through gas-phase or aqueous phase oxidation of SO2, have implications for climate forcing because only sulfate produced in the gas-phase can nucleate new aerosol particles. Thus, constraining the formation pathways of sulfate in different climates is important to assess its climate impact. O-17 excess of sulfate (Δ17O(SO42-)) can be used to distinguish the formation pathways of atmospheric sulfate. Δ17O(SO42-) measured from an Antarctic (Vostok) ice core covering a full climate cycle suggested that gas-phase oxidation was more important in the last glacial period than that in the interglacial periods before and after, though its cause was not fully understood. We present new results of Δ17O(SO42-) measured from a Greenland (GISP2) ice core covering the last glacial period. Compared to the Vostok results, the GISP2 results display a similar Δ17O(SO42-) - temperature/climate relationship, but with much smaller Δ17O(SO42-) values in preindustrial Holocene (PIH). This difference seen in PIH is likely because aqueous-phase oxidation of SO2 by H2O2 is more important in the Northern Hemisphere than in the Southern Hemisphere, due to differences in cloud pH and oxidant abundances. Results from a new chemistry-climate model (ICECAP) suggest that the enhanced gas-phase oxidation in the glacial period in both hemispheres is due to 1) increased tropospheric OH production in mid- to high latitudes caused by enhanced UV-B radiation originating from reduced stratospheric ozone abundance and higher surface albedos over land and sea ice, and 2) reduced cloud fraction in the glacial climate. Implications for the global sulfur budget will be discussed.

  4. The record of Miocene climatic events in AND-2A drill core (Antarctica): Insights from provenance analyses of basement clasts

    Science.gov (United States)

    Sandroni, Sonia; Talarico, Franco M.

    2011-01-01

    This paper includes the results of a detailed quantitative provenance investigation on gravel-size clasts occurring within the late Early to Late Miocene sedimentary glacimarine section recovered for the first time by the AND-2A core in the SW sector of the Ross Sea (southern McMurdo Sound, Antarctica). This period of time is of crucial interest, as it includes two of the major Cenozoic events in the global climatic evolution: the mid-Miocene climatic optimum and the middle Miocene climate transition. Petrographical and mineral chemistry data on basement clasts allow to individuate two different diagnostic clast assemblages, which clearly suggest two specific sectors of southern Victoria Land as the most likely sources: the Mulock-Skelton glacier and the Koettlitz-Blue glacier regions. Distribution patterns reveal high fluctuations of the detritus source areas throughout the investigated core interval, variations which can be interpreted as the direct result of an evolving McMurdo Sound paleogeography during the late Early to Late Miocene. Consistently with sedimentological studies, gravel-fraction clast distribution patterns clearly testify that the Antarctic ice sheet experienced a dramatic contraction at ca. 17.35 ± 0.14 Ma (likely correlated to the onset of the climatic optimum), and in a gravel-fraction clasts show that the variations of paleoenvironmental drivers characterising this period were able to exert deep transformation of the Antarctic ice sheet and reveal the methodology to be a powerful tool for the reconstruction of paleo-glacial-flow direction and paleogeographic scenarios.

  5. Dating a 109.9 m ice core from Dome A (East Antarctica) with volcanic records and a firn densification model

    Institute of Scientific and Technical Information of China (English)

    LI ChuanJin; XIAO CunDe; HOU ShuGui; REN JiaWen; DING MingHu; GUO Rui

    2012-01-01

    A 109.9 m ice core was extracted at a location about 300 m away from the Dome A summit (80°00′S,77°21″E) by the Chinese team of the International Trans-Antarctic Science Expedition (ITASE) during the 21st Chinese National Antarctica Research Expedition (CHINARE) in January 2005.Two independent methods were used for dating the ice core,volcanic event markers shown by prominent non-sea-salt sulfate (nss-SO42-) and the Herron and Langway (H-L) fim densification model.Six prominent volcanic events (Agung 1963 AD,Tambora 1815 AD,Kuwae 1453 AD,Unknown 1259 AD,Taupo 186 AD and Pinatubo 1050 BC) were identified by comparison with other Antarctic ice cores.Based on the mean accumulation rates between adjacent events,we estimate the age at the firn pore close-off depth (102 m) was 3516±100 a BP.This is the oldest close-off age ever reported from the Antarctic and the Greenland ice sheets.Calculations using the H-L model sho,w that the age at the same depth is 3581±100 a BP.The two dating techniques differ by 65 years,or-1.8% of the record.We calculated the bottom age of the ice core as 4009±150 a BP using the volcanic d,ating method and 4115±150 a BP using the H-L model method.

  6. Gas records from the West Greenland ice margin covering the Last Glacial termination: a horizontal ice core

    DEFF Research Database (Denmark)

    Petrenko, V.; Severinghaus, J.P.; Brook, E.J.

    2006-01-01

    Certain sites along ice sheet margins provide an easily accessible and almost unlimited supply of ancient ice at the surface. Measurements of gases in trapped air from ice outcropping at Pakitsoq, West Greenland, demonstrate that ancient air is mostly well preserved. No alterations in delta O-18......-uniformly thinned, with many cross-cutting bands of bubble-free ice and dust. The cross-cutting features are associated with anomalies in both the gas and the ice records. With careful sampling to avoid these, the ice at Pakitsoq is suitable for recovery of large-volume samples of the ancient atmosphere...

  7. A 1750-1999 AD Atmospheric Record of East Asian Black Carbon Emissions from the Prospector-Russell Col Ice Core, Mt. Logan, Yukon Territory

    Science.gov (United States)

    Menking, J. A.; Kaspari, S.; Osterberg, E. C.; Fisher, D.

    2012-12-01

    Black carbon (BC), an aerosol created from the incomplete combustion of fossil and biofuels, absorbs sunlight causing warming in the atmosphere and cooling at the surface. BC deposited on snow and ice reduces the surface albedo, accelerating seasonal snowmelt and glacier retreat and influencing the regional water cycle and climate. Estimates place East Asia as the top BC producer worldwide. Recent studies suggest that increases in East Asian BC related to industrialization have influenced Asian climate by altering temperatures and the timing and magnitude of precipitation. East Asian BC emissions have been estimated using fossil fuel inventories, but observational data is needed to constrain the timing and magnitude of recent BC emissions changes in order to better assess the role of BC in recent climate change. Here we present a time series of East Asian atmospheric BC that spans 1750-1999 AD that was developed using an ice core collected at the Prospector-Russell (PR) Col on Mt. Logan, Yukon Territory, Canada. The PR Col ice core is ideal for developing a record of East Asian BC emissions because the Mt. Logan summit has been shown to capture Asian emissions transported across the Pacific Ocean. The Mt. Logan record shows increases in BC concentration occurring in the early 1980's related to the recent industrialization of East Asian nations. We utilize the BC record from Mt. Logan (1) for comparison with estimated East Asian emissions inventories, and (2) to assess the role of BC in recent climate change with respect to the timing and magnitude of changes in East Asian BC emissions.

  8. Elemental changes and alteration recorded by basaltic drill core samples recovered from in situ temperatures up to 345°C in the active, seawater-recharged Reykjanes geothermal system, Iceland

    Science.gov (United States)

    Fowler, Andrew P. G.; Zierenberg, Robert A.

    2016-11-01

    Hydrothermal activity results in element exchanges between seawater and oceanic crust that contribute to many aspects of ocean chemistry; therefore, improving knowledge of the associated chemical processes is of global significance. Hydrothermally altered basaltic drill core samples from the seawater-recharged Reykjanes geothermal system in Iceland record elemental gains and losses similar to those observed in samples of hydrothermally altered oceanic crust. At Reykjanes, rocks originally emplaced on the seafloor were buried by continued volcanism and subsided to the current depths (>2250 m below surface). These rocks integrate temperature-dependent elemental gains and losses from multiple stages of hydrothermal alteration that correspond to chemical exchanges observed in rocks from different crustal levels of submarine hydrothermal systems. Specifically, these lithologies have gained U, Mg, Zn, and Pb and have lost K, Rb, Ba, Cu, and light rare earth elements (La through Eu). Alteration and elemental gains and losses in lithologies emplaced on the seafloor can only be explained by a complex multistage hydrothermal alteration history. Reykjanes dolerite intrusions record alteration similar to that reported for the sheeted dike section of several examples of oceanic crust. Specifically, Reykjanes dolerites have lost K, Rb, Ba, and Pb, and gained Cu. The Reykjanes drill core samples provide a unique analog for seawater-oceanic crust reactions actively occurring at high temperatures (275-345°C) beneath a seafloor hydrothermal system.

  9. Core-needle biopsy versus repeat fine-needle aspiration for thyroid nodules initially read as atypia/follicular lesion of undetermined significance.

    Science.gov (United States)

    Choi, Young Jun; Baek, Jung Hwan; Suh, Chong Hyun; Shim, Woo Hyun; Jeong, Boseul; Kim, Jae Kyun; Song, Dong Eun; Kim, Tae Yong; Chung, Ki-Wook; Lee, Jeong Hyun

    2017-02-01

    The purpose of this study was to evaluate the role of core-needle biopsy (CNB) by comparing the results of CNB and repeat fine-needle aspiration (FNA) for thyroid nodules that are initially read as atypia/follicular lesion of undetermined significance (AUS/FLUS) on FNA. Among 2631 initial AUS/FLUS FNA results, 505 consecutive nodules (295 repeat FNAs and 210 CNBs) were retrospectively analyzed. The primary outcome was inconclusive (ie, nondiagnostic or AUS/FLUS). The secondary outcomes included inconclusive results of the subcategory, risk factors for inconclusive results, and diagnostic performance. CNB demonstrated significantly fewer inconclusive results than repeat FNA for the overall nodules (40.9% vs 63%; p < .001). Repeat FNA and group FLUS were significant risk factors for inconclusive results (odds ratio = 1.92; p =.001 and odds ratio = 2.08; p <.001, respectively). All diagnostic performances using CNB were higher than repeat FNAs. CNB is more useful than repeat FNAs for reducing inconclusive results and improving the diagnostic performance of thyroid nodules with initial AUS/FLUS FNA results. © 2016 Wiley Periodicals, Inc. Head Neck 39: 361-369, 2017. © 2016 Wiley Periodicals, Inc.

  10. Organic acids: Differences in ice core records between Glac- ier 1, Tianshan, China and the polar areas

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Formate (HCOO-), acetate (CH3COO-), oxalate (C2O42-) and pyruvate((CO)C2O42-) are detected in a 14.08-m-long ice core recovered in Glacier 1 at the Urumqi riverhead, Tianshan, China, which is a mid-latitude alpine glacier (43°06′N, 86°49′E). the mean concentrations for the four organic acids in recent four decades are (102.8±147.3), (392.3±390.8), (6.9±14.8) and (4.2±8.3) ng/g, respectively, with the ratio for HCOO-/CH3COO- of 0.34 ± 0.43. They represent the major acid components, and originate mainly from anthropogenic emission in the nearby industrial cities. Compared with Greenland and Antarctica, Glacier 1 is much higher in carboxylic acids, which were not subjected to long distance transportation as well as complicated atmospheric reactions. The alpine glacier can be, therefore, useful to re-constructing human pollution scenario to the regional at-mosphere.

  11. High-resolution provenance of desert dust deposited on Mt. Elbrus, Caucasus in 2009–2012 using snow pit and firn core records

    Directory of Open Access Journals (Sweden)

    S. Kutuzov

    2013-09-01

    Full Text Available The first record of dust deposition events on Mt. Elbrus, Caucasus Mountains derived from a snow pit and a shallow firn core is presented for the 2009–2012 period. A combination of isotopic analysis, SEVIRI red-green-blue composite imagery, MODIS atmospheric optical depth fields derived using the Deep Blue algorithm, air mass trajectories derived using the HYSPLIT model and analyses of meteorological data enabled identification of dust source regions with high temporal (hours and spatial (ca. 20–100 km resolution. Seventeen dust deposition events were detected; fourteen occurred in March–June, one in February and two in October. Four events originated in the Sahara, predominantly in northeastern Libya and eastern Algeria. Thirteen events originated in the Middle East, in the Syrian Desert and northern Mesopotamia, from a mixture of natural and anthropogenic sources. Dust transportation from Sahara was associated with vigorous Saharan depressions, strong surface winds in the source region and mid-tropospheric southwesterly flow with daily winds speeds of 20–30 m s−1 at 700 hPa level. Although these events were less frequent than those originating in the Middle East, they resulted in higher dust concentrations in snow. Dust transportation from the Middle East was associated with weaker depressions forming over the source region, high pressure centred over or extending towards the Caspian Sea and a weaker southerly or southeasterly flow towards the Caucasus Mountains with daily wind speeds of 12–18 m s−1 at 700 hPa level. Higher concentrations of nitrates and ammonium characterised dust from the Middle East deposited on Mt. Elbrus in 2009 indicating contribution of anthropogenic sources. The modal values of particle size distributions ranged between 1.98 μm and 4.16 μm. Most samples were characterised by modal values of 2.0–2.8 μm with an average of 2.6 μm and there was no significant difference between dust from the Sahara and

  12. Historical records from dated sediment cores reveal the multidecadal dynamic of the toxic dinoflagellate Alexandrium minutum in the Bay of Brest (France).

    Science.gov (United States)

    Klouch, Khadidja Z; Schmidt, Sabine; Andrieux-Loyer, Françoise; Le Gac, Mickaël; Hervio-Heath, Dominique; Qui-Minet, Zujaila N; Quéré, Julien; Bigeard, Estelle; Guillou, Laure; Siano, Raffaele

    2016-07-01

    The multiannual dynamic of the cyst-forming and toxic marine dinoflagellate Alexandrium minutum was studied over a time scale of about 150 years by a paleoecological approach based on ancient DNA (aDNA) quantification and cyst revivification data obtained from two dated sediment cores of the Bay of Brest (Brittany, France). The first genetic traces of the species presence in the study area dated back to 1873 ± 6. Specific aDNA could be quantified by a newly developed real-time PCR assay in the upper core layers, in which the germination of the species (in up to 17-19-year-old sediments) was also obtained. In both cores studied, our quantitative paleogenetic data showed a statistically significant increasing trend in the abundance of A. minutum ITS1 rDNA copies over time, corroborating three decades of local plankton data that have documented an increasing trend in the species cell abundance. By comparison, paleogenetic data of the dinoflagellate Scrippsiella donghaienis did not show a coherent trend between the cores studied, supporting the hypothesis of the existence of a species-specific dynamic of A. minutum in the study area. This work contributes to the development of paleoecological research, further showing its potential for biogeographical, ecological and evolutionary studies on marine microbes.

  13. Stable carbon and oxygen isotopes of four planktonic foraminiferal species from core-top sediments of the Indonesian throughflow region and their significance

    Institute of Scientific and Technical Information of China (English)

    ZHANG Peng; ZURAIDA Rina; XU Jian; YANG Ce

    2016-01-01

    Horizontal and vertical distributions of δ18O and δ13C were investigated in shells of four planktonic foraminiferal species, Globigerinoides ruber, Globigerinoides sacculifer, Pulleniatina obliquiloculata and Neogloboquedrina dutertrei, from a total of 62 core-top sediment samples from the Indonesian throughflow region. Results were compared to modern hydrologic conditions in order to explore potential of proxies in reconstructing fluvial discharge and upper ocean water column characteristics in this region. Our results show that, in the Makassar Strait, both of depleted δ18O and δ13C of these four species were linked to freshwater input. In the Bali Sea, however, depleted δ18O and δ13C for these species may be due to different reasons. Depleted δ18O was a result of freshwater input and as well influenced by along-shore currents while depleted δ13C was more likely due to the Java-Sumatra upwelling. Comparison of shell δ18O records and hydrographic data of World Ocean Atlas 2005 suggests that G. ruber and G. sacculifer calcify within the mixed-layer, respectively at 0–50 m and 20–75 m water depth, and P. obliquiloculata and N. dutertrei within the upper thermocline, both at 75–125 m water depth. N. dutertrei calcifies at slightly deeper water depth than P. obliquiloculata does. In general, δ13C values of both G. ruber and G. sacculifer are larger than those of P. obliquiloculata and N. dutertrei at all sites, possibly related to depth habitats of these species and vertical distribution of nutrients in the Indonesian throughflow region.

  14. New sedimentary-core records and a recent co-seismic turbidite help to unravel the paleoseismicity of the Hikurangi Subduction Zone, New Zealand

    Science.gov (United States)

    Barnes, Philip; Orpin, Alan; Howarth, Jamie; Patton, Jason; Lamarche, Geoffroy; Woelz, Susanne; Hopkins, Jenni; Gerring, Peter; Mitchell, John; Quinn, Will; McKeown, Monique; Ganguly, Aratrika; Banks, Simon; Davidson, Sam

    2017-04-01

    The Hikurangi margin straddles the convergent boundary between the Pacific and Australia tectonic plates and is New Zealand's potentially largest earthquake and tsunami hazard. The 3000 m-deep Hikurangi Trough, off eastern Marlborough, Wairarapa, Hawkes Bay, and East Cape, marks the location where the Pacific plate is subducting beneath the eastern continental margin of the North Island and northeastern South Island. To date the Hikurangi margin has a short historical record relative to the recurrence of great earthquakes and tsunami, and consequently the associated hazard remains poorly constrained. In October 2016 a new, international, 5-year project commenced to evaluate the pre-historic earthquake history of the margin. In November 2016 a RV Tangaroa voyage acquired 50 sediment cores up to 5.5 m long from sites on the continental margin between the Kaikoura coast and Poverty Bay. Core sites were selected using available 30 kHz multibeam bathymetry and backscatter data, sub-bottom acoustic profiles, archived sediment samples, and results from numerical modelling of turbidity currents. Sites fell into three general categories: turbidite distributary systems; small isolated slope-basins; and Hikurangi Channel, levees, and trough. Typical of the margin, the terrigenous-dominated sequence included layers of gravel, sand, mud, and volcanic ash. Many of these layers are turbidites, some of which may have been triggered by strong shaking associated with earthquakes (subduction megathrust and other coastal faults). Some cores contain up to 25 individual turbidites. This library of turbidites may provide the basis of new paleoseismic records that span several hundred kilometres of strike along the plate boundary. During the voyage the 14th November 2016 (NZDT) Mw 7.8 Kaikoura Earthquake occurred, causing strong ground shaking beneath the Kaikoura Canyon region. Sampling with a multicorer within five days of the earthquake, we recovered what appeared to be a very recently

  15. Sulfur mass loading of the atmosphere from volcanic eruptions: Calibration of the ice core record on basis of sulfate aerosol deposition in polar regions from the 1982 El Chichon eruption

    Science.gov (United States)

    Sigurdsson, Haraldur; Laj, Paolo

    1990-01-01

    Major volcanic eruptions disperse large quantities of sulfur compound throughout the Earth's atmosphere. The sulfuric acid aerosols resulting from such eruptions are scavenged by snow within the polar regions and appear in polar ice cores as elevated acidity layers. Glacio-chemical studies of ice cores can, thus, provide a record of past volcanism, as well as the means for understanding the fate of volcanic sulfur in the atmosphere. The primary objectives of this project are to study the chemistry and physical properties of volcanic fallout in a Greenland Ice Core in order to evaluate the impact of the volcanic gases on the atmospheric chemistry and the total atmospheric mass of volcanic aerosols emitted by major volcanic eruptions. We propose to compare the ice core record to other atmospheric records performed during the last 10 years to investigate transport and deposition of volcanic materials.

  16. Integrated stratigraphy of the Smirra Coring: a new reference sedimentary record for the early Paleogene from the Umbria-Marche Basin (Northern Apennines, Italy)

    Science.gov (United States)

    Turtù, Antonio; Lauretano, Vittoria; Catanzariti, Rita; Galeotti, Simone; Lanci, Luca; Moretti, Matteo; Lourens, Lucas J.

    2016-04-01

    The early Paleogene represents a critical time interval in Earth's history characterized by prolonged greenhouse conditions, culminating in a series of extreme global warming events (i.e. hyperthermals), as well as large uncertainties in the Geological Time Scale. Therefore new, high-resolution, geological records are crucial in providing novel constraints on these topics. The Paleogene Umbria-Marche sections of the Northern Apennines (Italy) have shown to be suitable for integrated stratigraphy allowing regional-to-global correlations and environmental reconstructions across this time interval. Among several well-known sections, a new sedimentary record is provided by the Smirra Coring, which recovered an undisturbed sequence of rocks (~120 m from 4 overlapping holes) spanning the upper Scaglia Fms. (early Paleocene - middle Eocene) of the Umbria-Marche pelagic succession. Here we present a new, high-resolution, integrated stratigraphic framework (magnetostratigraphy, calcareous nannofossil biostratigraphy, physical properties, calibrated XRF core scanning and cyclostratigraphy) of the ~93 m composite section drilled in Smirra Holes 1 and 2. The succession extends almost continuously, with modest tectonic disturbance affecting its lowermost part with minor faulting. The resulting magnetic stratigraphy defines a succession of normal and reversed polarity magnetozones. The correlation of the paleomagnetic polarity sequence with the latest Geomagnetic Polarity Timescales (GPTSs; e.g. CK95, GTS 2004 and 2012), also constrained through nannofossil biostratigraphy, shows that the section spans the late Paleocene - middle Eocene from chrons C21n (~46 Ma) to C26r (~60 Ma). The overall sedimentation rates computed at Smirra are fully comparable with those from coeval sections from the Umbria-Marche Basin, ranging from ~10 m/Ma, between chrons C21n and C22n, to ~6 m/Ma, between chrons C22r and the base of the section. However, the sedimentation rates vary considerably

  17. New insights on the anatomy of abrupt climate changes based on high-resolution ice core records from NorthGRIP (Greenland)

    Science.gov (United States)

    Capron, E.; Rasmussen, S.; Popp, T. J.; Vaughn, B. H.; Gkinis, V.; Erhardt, T.; Fischer, H.; Blunier, T.; Landais, A.; Pedro, J. B.; Steffensen, J. P.; Svensson, A.; Vinther, B.

    2016-12-01

    The millennial-scale succession of Greenland Stadials (GS) and Greenland Interstadials (GI) illustrates the Greenland expression of the well-known sequence of Dansgaard-Oeschger (DO) events, within which we observe additional climate variations of decadal to centennial-scale duration. Various paradigms, mostly based on interactions between the cryosphere and the ocean, have been proposed to explain the existence and evolution of DO events. Annual to decadal scale records of environmental and climatic regional changes over the rapid transitions are needed to assess whether climate model outputs based on a particular mechanism are consistent with the observed spatial pattern and temporal phasing. Here we present new multiannual resolution stable water isotope measurements (ice δ18O and δD) and annually resolved ion chemistry records from the NorthGRIP ice core. Because these tracers imprint the signatures of different parts of the Northern Hemisphere climate system, we can map the anatomy - the spatial and temporal signature of climate and environmental changes - associated with abrupt transitions (from GS to GI and vice-versa) occurring during Marine Isotopic Stage (MIS) 4. We determine via a statistical approach the timing and duration of the transitions, along with the amplitude of the local and regional changes associated with each Greenland warming and cooling phase. We quantify similarities and differences in the sequences of events through a comparison with results obtained for MIS 3 abrupt transitions and results from the NEEM ice core for selected transitions. The anatomy of abrupt climate changes appears to be different from one event to the next, suggesting that the mechanisms at play are not identical for all of them. We discuss the possible influence of (1) the Heinrich Stadials (i.e. GS during which a Heinrich Event occurred) and of (2) the long term evolution of the climate system on the different decadal to centennial-scale sequences of events

  18. 以电子病历为核心的数字化医院建设%Construction of Digital Hospital Taking Electronic Medical Records as Core

    Institute of Scientific and Technical Information of China (English)

    贺乐平

    2013-01-01

    以电子病历为核心的医院信息化建设是卫生部公立医院改革的重要组成部分,同时电子病历也是医院等级评审的主要内容.随着医改的不断深入,医院信息化建设的重心逐渐向临床系统转移.本文介绍内蒙古自治区人民医院以电子病历为核心的数字化医院建设的现状、系统的特点以及如何利用社会资源共建信息化的相关经验及建议,以期对其它兄弟医院的信息化建设起到启发和借鉴作用.%The hospital information construction taking electronic medical records as core is an important part of the reform of public hospitals of the Ministry of Health, meanwhile it is the main content of a hospital grade. With the deepening of health care reform, the main emphasis of hospital information construction is gradually transferred to the clinical information systems. This article describes the status and characteristics of digital hospital construction that takes electronic medical records as the core about Inner Mongolia People' s Hospital, and some experience and recommendations about how to use social resources to build informa-tization, in order to inspire and make reference for other hospitals information construction.

  19. Rapid changes in ice core gas records - Part 2: Understanding the rapid rise in atmospheric CO2 at the onset of the Bølling/Allerød

    Science.gov (United States)

    Köhler, P.; Knorr, G.; Buiron, D.; Lourantou, A.; Chappellaz, J.

    2010-08-01

    During the last glacial/interglacial transition the Earth's climate underwent rapid changes around 14.6 kyr ago. Temperature proxies from ice cores revealed the onset of the Bølling/Allerød (B/A) warm period in the north and the start of the Antarctic Cold Reversal in the south. Furthermore, the B/A is accompanied by a rapid sea level rise of about 20 m during meltwater pulse (MWP) 1A, whose exact timing is matter of current debate. In situ measured CO2 in the EPICA Dome C (EDC) ice core also revealed a remarkable jump of 10±1 ppmv in 230 yr at the same time. Allowing for the age distribution of CO2 in firn we here show, that atmospheric CO2 rose by 20-35 ppmv in less than 200 yr, which is a factor of 2-3.5 larger than the CO2 signal recorded in situ in EDC. Based on the estimated airborne fraction of 0.17 of CO2 we infer that 125 Pg of carbon need to be released to the atmosphere to produce such a peak. Most of the carbon might have been activated as consequence of continental shelf flooding during MWP-1A. This impact of rapid sea level rise on atmospheric CO2 distinguishes the B/A from other Dansgaard/Oeschger events of the last 60 kyr, potentially defining the point of no return during the last deglaciation.

  20. Decadal climatic variations recorded in Guliya ice core and comparison with the historical documentary data from East China during the last 2000 years

    Institute of Scientific and Technical Information of China (English)

    施雅风; 姚檀栋; 杨保

    1999-01-01

    The high-resolution records of δ18O and snow accumulation variations from the Guliya ice core provide valuable data for research on climatic variations at a decadal resolution during the past 2000 years in China. Based on the ice core data, five spells have been divided: the warm and wet period before 270 AD, the cold and dry period between 280 and 970 AD, the moderate and dry period between 970 and 1510 AD, the well-defined" Little Ice Age "with drastic cold-warm fluctuations between 1510 and 1930 AD and the warming period since 1930 AD. According to the combination of temperature and precipitation, cold events (55 times) surpass warm ones (26 times), and dry events (55 times) surpass wet ones (45 times). Cold-wet events (14 times) are less than cold-dry ones (16 times), while warmwet events (10 times) are more than warm-dry ones (4 times). If the difference of 2‰ in δ18O (corresponding to 3K in temperature) between two or three adjacent decades is taken as the criterion of it, the abrupt chan

  1. Climate and Low Latitude Water Cycle Variations Over the Last 300 ka Using Ice Core Records and iLOVECLIM Integration

    Science.gov (United States)

    Extier, Thomas; Landais, Amaelle; Roche, Didier; Bréant, Camille; Bazin, Lucie; Prie, Frederic; François, Louis

    2017-04-01

    The Quaternary is characterized by a succession of glacial and interglacial periods recorded in various climatic archives from high to low latitudes. Antarctic ice cores provide high latitude climate reconstruction from water isotopes as well as global proxy records such as greenhouse gas concentrations. Within global tracers, δ18O of O2 or δ18Oatm is a quite complex tracer which reflects global variations of the low latitude water cycle and vegetation changes. The last two terminations (TI 20-11 ka and TII 136-128 ka) are already well documented and display a high resolution δ18Oatm signal with large amplitude changes, whereas the changes are smaller and poorly documented for the TIII (around 245 ka). Here we display new δ18Oatm data over the last 300 ka on the Dome C ice core in order to compare the δ18Oatm dynamics over the last three terminations. The new high resolution δ18Oatm data covering the Termination III confirm the smaller δ18Oatm amplitude changes compared to TI and TII. Moreover, the δ18Oatm changes of TIII appear to be divided in several steps. The δ18Oatm trapped in Dome C ice cores also shows strong similarity with the 65°N summer insolation and the precession signal on orbital timescales as well as with the δ18Ocalcite measured in the Asian speleothems, suggesting a link with the monsoon dynamics. However, the quantitative interpretation of δ18Oatm is limited by our knowledge of past oxygen fluxes. We present here the first step toward a more quantitative interpretation of δ18Oatm variations through the use of the iLOVECLIM intermediate complexity model with a new vegetation module CARAIB (Warnant et al., 1994; Otto et al., 2002; Laurent et al., 2008; Dury et al., 2011). Through considering more plant functional types (PFTs) and more accurate biosphere productivity variations than the previous module, CARAIB will be helpful to quantify the impact of the biosphere changes on the δ18Oatm.

  2. Superfund explanation of significant difference for the record of decision (EPA Region 3): Fairchild, Intel, and Raytheon Sites, (Mew Study Area), Mountain View, CA, September 1990

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-02-01

    The purpose of the document is to explain the significant differences between the Record of Decision (ROD) signed by the U.S. Environmental Protection Agency (EPA) on June 9, 1989 (PB90-118225) and the remedy that will be implemented at the Middlefield/Ellis/Whisman Study Area (MEW Site). The document provides a brief background on the MEW Site, describes the change to the ROD that EPA is now making and explains the ways in which this change affects implementation of the remedy selected by EPA in June of 1989.

  3. Head-camera video recordings of trauma core competency procedures can evaluate surgical resident's technical performance as well as colocated evaluators.

    Science.gov (United States)

    Mackenzie, Colin F; Pasley, Jason; Garofalo, Evan; Shackelford, Stacy; Chen, Hegang; Longinaker, Nyaradzo; Granite, Guinevere; Pugh, Kristy; Hagegeorge, George; Tisherman, Samuel A

    2017-07-01

    Unbiased evaluation of trauma core competency procedures is necessary to determine if residency and predeployment training courses are useful. We tested whether a previously validated individual procedure score (IPS) for individual procedure vascular exposure and fasciotomy (FAS) performance skills could discriminate training status by comparing IPS of evaluators colocated with surgeons to blind video evaluations. Performance of axillary artery (AA), brachial artery (BA), and femoral artery (FA) vascular exposures and lower extremity FAS on fresh cadavers by 40 PGY-2 to PGY-6 residents was video-recorded from head-mounted cameras. Two colocated trained evaluators assessed IPS before and after training. One surgeon in each pretraining tertile of IPS for each procedure was randomly identified for blind video review. The same 12 surgeons were video-recorded repeating the procedures less than 4 weeks after training. Five evaluators independently reviewed all 96 randomly arranged deidentified videos. Inter-rater reliability/consistency, intraclass correlation coefficients were compared by colocated versus video review of IPS, and errors. Study methodology and bias were judged by Medical Education Research Study Quality Instrument and the Quality Assessment of Diagnostic Accuracy Studies criteria. There were no differences (p ≥ 0.5) in IPS for AA, FA, FAS, whether evaluators were colocated or reviewed video recordings. Evaluator consistency was 0.29 (BA) - 0.77 (FA). Video and colocated evaluators were in total agreement (p = 1.0) for error recognition. Intraclass correlation coefficient was 0.73 to 0.92, dependent on procedure. Correlations video versus colocated evaluations were 0.5 to 0.9. Except for BA, blinded video evaluators discriminated (p competency. Prognostic study, level II.

  4. Air-snow transfer of nitrate on the East Antarctic Plateau - Part 2: An isotopic model for the interpretation of deep ice-core records

    Science.gov (United States)

    Erbland, J.; Savarino, J.; Morin, S.; France, J. L.; Frey, M. M.; King, M. D.

    2015-10-01

    Unraveling the modern budget of reactive nitrogen on the Antarctic Plateau is critical for the interpretation of ice-core records of nitrate. This requires accounting for nitrate recycling processes occurring in near-surface snow and the overlying atmospheric boundary layer. Not only concentration measurements but also isotopic ratios of nitrogen and oxygen in nitrate provide constraints on the processes at play. However, due to the large number of intertwined chemical and physical phenomena involved, numerical modeling is required to test hypotheses in a quantitative manner. Here we introduce the model TRANSITS (TRansfer of Atmospheric Nitrate Stable Isotopes To the Snow), a novel conceptual, multi-layer and one-dimensional model representing the impact of processes operating on nitrate at the air-snow interface on the East Antarctic Plateau, in terms of concentrations (mass fraction) and nitrogen (δ15N) and oxygen isotopic composition (17O excess, Δ17O) in nitrate. At the air-snow interface at Dome C (DC; 75° 06' S, 123° 19' E), the model reproduces well the values of δ15N in atmospheric and surface snow (skin layer) nitrate as well as in the δ15N profile in DC snow, including the observed extraordinary high positive values (around +300 ‰) below 2 cm. The model also captures the observed variability in nitrate mass fraction in the snow. While oxygen data are qualitatively reproduced at the air-snow interface at DC and in East Antarctica, the simulated Δ17O values underestimate the observed Δ17O values by several per mill. This is explained by the simplifications made in the description of the atmospheric cycling and oxidation of NO2 as well as by our lack of understanding of the NOx chemistry at Dome C. The model reproduces well the sensitivity of δ15N, Δ17O and the apparent fractionation constants (15ϵapp, 17Eapp) to the snow accumulation rate. Building on this development, we propose a framework for the interpretation of nitrate records

  5. Palaeoenvironmental changes from pollen record in deep sea core PC-1 from northern Okinawa Trough, East China Sea during the past 24 ka

    Institute of Scientific and Technical Information of China (English)

    XU HongYan; CHANG FengMing; LUO YunLi; SUN XiangJun

    2009-01-01

    A pollen record of core PC-1 from the northern Okinawa Trough, East China Sea (ECS), provides in-formation on vegetation and climate changes since 24 cal. kaBP. A total of 103 samples were palyno-logically analyzed at 8 cm intervals with a time resolution of 230 a. Four pollen zones are recognized: zone I (812-715 cm, 24.2-21.1 cal. kaBP), zone II (715-451 cm, 21.1 -15.2 cal. kaBP), zone Ⅲ (451 -251 cm, 15.2-10.8 cal. kaBP), zone Ⅳ (251-0 cm, 10.8-0.3 cal. kaBP), corresponding to Late MIS 3, Last Glacial Maximum (LGM), deglaciation and Holocene, respectively. The LGM is characterized by the dominance of herbs, mainly Artemisia, and high pollen influx, implying an open vegetation on the ex-posed continental shelf and e cool and dry climate. The deglaciation is a climate warming stage with Pinus percentage increased and Artemisia percentage decreased and a rapid sea-level rise. The Holo-cene is characterized by predominance of tree pollen with rapid increase in Castanea-Castanopsis in-dicating the development of mixed evergreen and deciduous broad-leaved forest and a warm, humid climate. Low pollen influx during the Holocene probably implies submergence of the continental shelf and retreat of the pollen source area. The vegetation indicated by pollen assemblage found in this up-per zone is consistent with the present vegetation found in Kyushu, Japan. Originating from the humid mountain area of North Luzon of the Philippines, Tasmania and New Zealand, Phyllocladus with spo-radic occurrence throughout PC-1 core probably suggests the influence of Palaeo-Kuroshio Current or intense summer monsoon. The observed changes in Pinus and Herbs percentage indicate fluctuations of the sea level, and high Pinus percentage corresponds to high sea level. Spectrum analysis of the pollen percentage record reveals many millennial-scale periodicities, such as periodicities of 6.8, 3.8, 2.2, 1.6 ka.

  6. Radiocarbon analysis in an Alpine ice core: record of anthropogenic and biogenic contributions to carbonaceous aerosols in the past (1650–1940

    Directory of Open Access Journals (Sweden)

    T. M. Jenk

    2006-01-01

    Full Text Available Long-term concentration records of carbonaceous particles (CP are of increasing interest in climate research due to their not yet completely understood effects on climate. Nevertheless, only poor data on their concentrations and sources before the 20th century are available. We present a first long-term record of organic carbon (OC and elemental carbon (EC concentrations – the two main fractions of CP – along with the corresponding fraction of modern carbon (fM derived from radiocarbon (14C analysis in ice. This allows a distinction and quantification of natural (biogenic and anthropogenic (fossil sources in the past. CP were extracted from an ice archive, with resulting carbon quantities in the microgram range. Analysis of 14C by accelerator mass spectrometry (AMS was therefore highly demanding. We analysed 33 samples of 0.4 to 1 kg ice from a 150.5 m long ice core retrieved at Fiescherhorn glacier in December 2002 (46°33'3.2" N, 08°04'0.4" E; 3900 m a.s.l.. Samples were taken from bedrock up to the firn/ice transition, covering the time period 1650–1940 and thus the transition from the pre-industrial to the industrial era. Before ~1850, OC was approaching a purely biogenic origin with a mean concentration of 24 μg kg−1 and a standard deviation of 7 μg kg−1. In 1940, OC concentration was about a factor of 3 higher than this biogenic background, almost half of it originating from anthropogenic sources, i.e. from combustion of fossil fuels. The biogenic EC concentration was nearly constant over the examined time period with 6 μg kg−1 and a standard deviation of 1 μg kg−1. In 1940, the additional anthropogenic input of atmospheric EC was about 50 μg kg−1.

  7. Core benefits

    National Research Council Canada - National Science Library

    Keith, Brian W

    2010-01-01

    This SPEC Kit explores the core employment benefits of retirement, and life, health, and other insurance -benefits that are typically decided by the parent institution and often have significant governmental regulation...

  8. Eight Million Years of Land-Based Antarctic Ice Sheet Stability Recorded By In Situ 10Be from the ANDRILL-1B Core

    Science.gov (United States)

    Shakun, J. D.; Corbett, L. B.; Bierman, P. R.

    2015-12-01

    The response of the East Antarctic Ice Sheet (EAIS) to Pliocene warmth provides a critical way to gauge its sensitivity to climate change. Considerable uncertainty surrounds the Pliocene behavior of the EAIS, however. For instance, global sea level estimates for the mid-Pliocene warm period range from 30 m, and numerous cosmogenic nuclide and sedimentological studies from the Transantarctic Mountains imply extreme landscape stability over the last several Myr whereas ocean records suggest orbital-scale instability of at least marine-based sectors of the ice sheet. These stabilist versus dynamicist views are difficult to resolve because onshore records are generally biased toward intervals of expanded ice cover and limited to areas with exposed land, while marine sediments typically provide indirect evidence for conditions on land and cannot distinguish between marine versus land-based ice sheet collapse. The AND-1B marine sediment core drilled beneath the Ross Ice Shelf contains a remarkably complete late Cenozoic sequence of glacial diamictons sourced from the adjacent EAIS, intercalated with open-water sediments likely associated with West Antarctic Ice Sheet collapse. We measured concentrations of in situ 10Be - produced only when ice cover is reduced and the landscape is exposed - in eight samples of glacially-derived quartz sand from AND-1B spanning parts of the last 8 Myr. Decay-corrected concentrations are low and show a long-term decline from 13,000 atoms/g to 1000 atoms/g over the record. These low values and the monotonic trend suggest that land-based ice sheet sectors have experienced little, if any, exposure during the past 8 Myr; the 10Be concentrations we measured are equivalent to only centuries or a few kyr of surface exposure. Perhaps more likely, the small quantities of 10Be were produced prior to the establishment of a full EAIS in the mid-Miocene, and reflect deeply-exhumed and thus 10Be-poor material that has been radioactively decaying beneath

  9. Explanation of Significant Differences for the Record of Decision for Interim Actions in Zone 1, East Tennessee Technology Park, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    Bechtel Jacobs

    2011-02-01

    Zone 1 is a 1400-acre area outside the fence of the main plant at The East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee. The Record of Decision for Interim Actions in Zone, ETTP (Zone 1 Interim ROD) (DOE 2002) identifies the remedial actions for contaminated soil, buried waste, and subsurface infrastructure necessary to protect human health and to limit further contamination of groundwater. Since the Zone 1 Interim Record of Decision (ROD) was signed, new information has been obtained that requires the remedy to be modified as follows: (1) Change the end use in Contractor's Spoil Area (CSA) from unrestricted industrial to recreational; (2) Remove Exposure Units (EU5) ZI-50, 51, and 52 from the scope of the Zone I Interim ROD; (3) Change the end use of the duct bank corridor from unrestricted industrial to restricted industrial; and (4) Remove restriction for the disturbance of soils below 10 feet in Exposure Unit (EU) Z1-04. In accordance with 40 Code of Federal Regulations (CFR) 300.435, these scope modifications are a 'significant' change to the Zone 1 Interim ROD. In accordance with CERCLA Sect. 117 (c) and 40 CFR 300.435 (c)(2)(i), such a significant change is documented with an Explanation of Significant Differences (ESD). The purpose of this ESD is to make the changes listed above. This ESD is part of the Administrative Record file, and it, and other information supporting the selected remedy, can be found at the DOE Information Center, 475 Oak Ridge Turnpike, Oak Ridge, Tennessee 37830, from 8:00 a.m. to 5:00 p.m., Monday through Friday. The ORR is located in Roane and Anderson counties, within and adjacent to the corporate city limits of Oak Ridge, Tennessee. ETTP is located in Roane County near the northwest corner of the ORR. ETTP began operation during World War II as part of the Manhattan Project. The original mission of ETTP was to produce enriched uranium for use in atomic weapons. The plant produced enriched uranium from

  10. Investigating the hydrological significance of stalagmite geochemistry (Mg, Sr) using Sr isotope and particulate element records across the Late Glacial-to-Holocene transition

    Science.gov (United States)

    Belli, R.; Borsato, A.; Frisia, S.; Drysdale, R.; Maas, R.; Greig, A.

    2017-02-01

    The trace element and Sr isotope records in two coeval stalagmites characterized by different growth rates and flow regimes at Savi cave (Grotta Savi, NE Italy) reveal different sources and incorporation mechanisms for Mg and Sr. Mg is sourced primarily from dissolved cave host rock while particulate Mg derived from soil plays a subordinate role. The presence of particulate-borne Mg is inferred from the co-variation of Mg and particle-associated elements (Th, Al and Mn) which are preferentially concentrated in open columnar calcite layers. Variation in Mg concentrations corrected for particle-influenced components, the Mgc parameter, is controlled by water-rock interaction, with higher and lower Mgc during dry and wet phases, respectively. This is thought to reflect incongruent dissolution of Mg-rich phases. Correction of Sr concentrations for contributions from airborne exogenic Sr, based on 87Sr/86Sr ratios, yields the bedrock-only contribution (Src). Src variation in stalagmite calcite is influenced by speleothem growth rate and by variation of the calcite-water Sr partitioning in wet and dry phases, and only to a minor extent by incongruent dissolution of Mg-rich phases. Concentration profiles for Mgc and Srcg (corrected for growth rate effects) show inverse correlations and are inferred to show hydrological significance which is captured in a hydrological index, HI. We suggest HI provides robust information on water-rock interaction related to hydrological changes and can be utilized in both wet and semi-arid environments, provided the corrections for soil Mg and exogenic Sr can be applied with confidence. Application of the HI index allows correction of Grotta Savi oxygen isotope data, to yield a δ18Oc time series that shows when changes in moisture sources and atmospheric reorganization, or changes in moisture amount, were significant. This is especially evident during the Younger Dryas (YD). The Savi record supports the concept of a two-phase YD, marked by

  11. Significantly improved charge collection and interface injection in 3D BiVO4 based multilayered core-shell nanowire photocatalysts.

    Science.gov (United States)

    Zhang, Zemin; Li, Yunxia; Jiang, Xiao; Han, Weihua; Xie, Mingzheng; Wang, Fangcong; Xie, Erqing

    2017-09-11

    It is challenging to design a photocatalyst with high-efficiency light absorption, charge separation and even high-efficiency charge transfer. Here, we report a demonstration by utilizing a three-dimensional multilayered core-shell nanowire array (rGO-ITO@BiVO4) as the composite photocatalyst. The core-shell structure can shorten the length of charge transfer and enhance light absorption through multireflection. RGO with defects can work as the charge transfer medium to improve the hole injection from semiconductor to electrolyte. Associated with the above effects, the Co-pi electrocatalyst modified rGO-ITO@BiVO4 photocatalyst yields a photocurrent of about 6.0 mA cm(-2) at 0.6 V vs. Ag/AgCl. Transient-state surface photovoltage measurement shows that the rGO layer can prolong the lifetime of the photogenerated holes through π-π interactions, so that more holes can participate in the water oxidation reaction.

  12. Antarctic-Wide Array of High-Resolution Ice Core Records Reveals Pervasive Lead Pollution Began in 1889 and Persists Today

    Science.gov (United States)

    McConnell, J. R.; Maselli, O. J.; Sigl, M.; Vallelonga, P.; Neumann, Thomas Allen; Anschutz, H.; Bales, R. C.; Curran, M. A. J.; Das, S. B.; Edwards, R.; Kipfstuhl, S.; Layman, L.; Thomas, E. R.

    2014-01-01

    Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21st century.

  13. Two ice-core delta O-18 records from Svalbard illustrating climate and sea-ice variability over the last 400 years

    NARCIS (Netherlands)

    Isaksson, E; Kohler, J; Pohjola, [No Value; Moore, J; Igarashi, M; Karlof, L; Martma, T; Meijer, H; Motoyama, H; Vaikmae, R; van de Wal, RSW; Pohjola, Veijo; Karlöf, Lars; Vaikmäe, Rein; Wal, Roderik S.W. van de; Kohler, 27967

    2005-01-01

    Ice cores from the relatively low-lying ice caps in Svalbard have not been widely exploited in climatic studies owing to uncertainties about the effect of meltwater percolation. However, results from two new Svalbard ice cores, at Lomonosovfonna and Austfonna, have shown that with careful site selec

  14. Preliminary results of the close-off depth and the stable isotopic records along a 109.91 m ice core from Dome A, Antarctica

    Institute of Scientific and Technical Information of China (English)

    HOU ShuGui; LI YuanSheng; XIAO CunDe; PANG HongXi; XU JianZhong

    2009-01-01

    A 109.91 m ice core was recovered from Dome A (or Dome Argus), the highest ice feature in Antarctica,during the 2004/05 austral summer by the 21st Chinese National Antarctic Research Expedition (CHINARE-21). Both methane profile along the core and firn densification model calculation suggest that the close-off depth is at about 102.0 m with an ice age about 4200 a. Stable isotopes (δ~(18)O and δD) of the chips samples produced during each run of ice core drilling at Dome A, together with those of the other cores recovered from the eastern inland Antarctica, suggest a relative stable climate with a tem-perature fluctuation amplitude about ±0.6℃ at the eastern inland Antarctica during the late Holocene.The average d-excess (or d=δD-8δ~(18)O) of 17.1‰ along the Dome A core is probably the highest among the Antarctic inland ice cores, which may be resulted from the kinetic fractionation during the snow formation under an oversaturation condition. Moreover, the increasing trend of d-excess during the late Holocene reflects mainly the migration of the water source area for precipitation at Dome A towards low latitudes. This paper presents the first results of a shallow ice core recovered from the unexplored highest area of the Antarctic ice sheet, providing a background for the proposing deep ice core drilling at Dome A.

  15. Preliminary results of the close-off depth and the stable isotopic records along a 109.91 m ice core from Dome A, Antarctica

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A 109.91 m ice core was recovered from Dome A (or Dome Argus), the highest ice feature in Antarctica, during the 2004/05 austral summer by the 21st Chinese National Antarctic Research Expedition (CHINARE-21). Both methane profile along the core and firn densification model calculation suggest that the close-off depth is at about 102.0 m with an ice age about 4200 a. Stable isotopes (δ18O and δD) of the chips samples produced during each run of ice core drilling at Dome A, together with those of the other cores recovered from the eastern inland Antarctica, suggest a relative stable climate with a temperature fluctuation amplitude about ±0.6℃ at the eastern inland Antarctica during the late Holocene. The average d-excess (or d =δ D-8δ 18O) of 17.1‰ along the Dome A core is probably the highest among the Antarctic inland ice cores, which may be resulted from the kinetic fractionation during the snow formation under an oversaturation condition. Moreover, the increasing trend of d-excess during the late Holocene reflects mainly the migration of the water source area for precipitation at Dome A towards low latitudes. This paper presents the first results of a shallow ice core recovered from the unexplored highest area of the Antarctic ice sheet, providing a background for the proposing deep ice core drilling at Dome A.

  16. astrophysical significance

    Directory of Open Access Journals (Sweden)

    Dartois E.

    2014-02-01

    Full Text Available Clathrate hydrates, ice inclusion compounds, are of major importance for the Earth’s permafrost regions and may control the stability of gases in many astrophysical bodies such as the planets, comets and possibly interstellar grains. Their physical behavior may provide a trapping mechanism to modify the absolute and relative composition of icy bodies that could be the source of late-time injection of gaseous species in planetary atmospheres or hot cores. In this study, we provide and discuss laboratory-recorded infrared signatures of clathrate hydrates in the near to mid-infrared and the implications for space-based astrophysical tele-detection in order to constrain their possible presence.

  17. Atmospheric Deposition History of Trace Metals and Metalloids for the Last 200 Years Recorded by Three Peat Cores in Great Hinggan Mountain, Northeast China

    Directory of Open Access Journals (Sweden)

    Kunshan Bao

    2015-03-01

    , even after the ban of leaded gasoline use in China. Emissions from coal and leaded gasoline combustions in northern China are regarded as one of the major sources of anthropogenic Pb input in this region; meanwhile, the long-distance transportation of Pb-bearing aerosols from Mongolia should be also taken into consideration. The reconstructed history of TMs’ pollution over the past ca. 200 years is in agreement with the industrial development in China and clearly illustrates the influence of human activities on local rural environments. This study shows the utility of taking multi-cores to show the heterogeneity in peat accumulation and applying PCA, EF and Pb isotope methods in multi-proxies analyses for establishing a high resolution geochemical metal record from peatland.

  18. Depositional record of trace metals and degree of contamination in core sediments from the Mandovi estuarine mangrove ecosystem, west coast of India.

    Science.gov (United States)

    Veerasingam, S; Vethamony, P; Mani Murali, R; Fernandes, B

    2015-02-15

    The concentrations of seven trace metals (Fe, Mn, Cu, Cr, Co, Pb and Zn) in three sediment cores were analysed to assess the depositional trends of metals and their contamination level in the Mandovi estuary, west coast of India. All sediment cores showed enrichment of trace metals in the upper part of core sediments and decrease in concentration with depth, suggesting excess of anthropogenic loading (including mining activities) occurred during the recent past. Scanning electron microscope (SEM) images distinguished the shape, size and structure of particles derived from lithogenic and anthropogenic sources in core sediments. The geo-accumulation index (I(geo)) values indicate that Mandovi estuary is 'moderately polluted' with Pb, whereas 'unpolluted to moderately polluted' with Fe, Mn, Cu, Cr, Co and Zn. The comparative analysis of trace metals revealed that Fe and Mn were highly enriched in the Mandovi estuary compared to all other Indian estuaries. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. A new ice-core record from Lomonosovfonna, Svalbard : viewing the 1920-97 data in relation to present climate and environmental conditions

    NARCIS (Netherlands)

    Isaksson, E; Pohjola, [No Value; Jauhiainen, T; Moore, J; Pinglot, JM; Vaikmae, R; van de Wal, RSW; Ivask, J; Karlof, L; Martma, T; Meijer, HAJ; Mulvaney, R; Thomassen, M; van den Broeke, M

    2001-01-01

    In 1997 a 121 m ice core was retrieved from Lomonosovfonna, the highest ice field in Spitsbergen, Svalbard (1250 m a.s.l.). Radar measurements indicate an ice depth of 126.5 m, and borehole temperature measurements show that the ice is below the melting point, High-resolution sampling of major ions,

  20. X-ray fluorescence core scanning of wet marine sediments: methods to improve quality and reproducibility of high-resolution paleoenvironmental records

    NARCIS (Netherlands)

    Hennekam, R.; de Lange, G.

    2012-01-01

    X-ray fluorescence (XRF) core-scanning is a convenient non-destructive tool to rapidly assess elemental variations in unprocessed sediments. However, substantial analytical deviations may occur in such data due to physical sedimentary properties. The consequences of these artifacts on element

  1. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today

    DEFF Research Database (Denmark)

    McConnell, J.R.; Maselli, OJ; Sigl, Michael

    2014-01-01

    Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead p...

  2. Palynological record of tropical rain forest vegetation and sea level fluctuations since 140 ka from sediment core, south-eastern Arabian sea.

    Digital Repository Service at National Institute of Oceanography (India)

    Farooqui, A.; Pattan, J.N.; Parthiban, G.; Srivastava, J.; Ranjana

    Palyno-chronological study of a 552 cm deep sediment core from the south-eastern Arabian Sea covers a time span of ~ 140 ka. The age estimate is based on oxygen isotopic data of planktic foraminifera. Six zones were identified on the basis...

  3. The Significance of Emotions and Professional Relations for Accommodating a Web-Based Ulcer Record and Improving Home-Based Care

    Directory of Open Access Journals (Sweden)

    Anne G. Ekeland

    2015-01-01

    Full Text Available Evidence of technological performance, medical improvements and economic effectiveness is generally considered sufficient for judging advances in healthcare. In this paper, I aim to add knowledge about the ways human emotions and professional relations play roles in the processes of accommodating new technologies for quality improvements. A newly-implemented, web-based ulcer record service for patients with chronic skin ulcers constitutes the case. After one year, only a few home care nurses were using the service, interacting with a specialist team. The result was disappointing, but the few users were enthusiastic. An explorative, qualitative study was initiated to understand the users, the processes that accounted for use and how improvements were enacted. In the paper, I expose the emotional aspects of the record accommodation by analyzing the ways emotions were translated in the process and how they influenced the improvements. I contend that use came about through a heterogeneous assemblage of ethical engagement and compassionate emotions stemming from frustration, combined with technological affordances and relations between different professionals. Certain aspects of the improvements are exposed. These are discussed as: (1 reconciliations between the medical facts and rational judgments, on one side, and the emotional and subjective values for judging quality, on the other; and (2 mediation between standardized and personalized care. The healing of ulcers was combined with a sense of purpose and wellbeing to validate improvements. Emotions were strongly involved, and the power of evaluative emotions and professional relations should be further explored to add to the understanding of innovation processes and to validate quality improvements.

  4. Paleomagnetic chronology and paleoenvironmental records from drill cores from the Hetao Basin and their implications for the formation of the Hobq Desert and the Yellow River

    Science.gov (United States)

    Li, Baofeng; Sun, Donghuai; Xu, Weihong; Wang, Fei; Liang, Baiqing; Ma, Zhiwei; Wang, Xin; Li, Zaijun; Chen, Fahu

    2017-01-01

    Reconstructing the Cenozoic environmental history of Hetao Basin, in the northern part of the Ordos Plateau in North China, is important not only for revealing the evolution of the Yellow River, but also for understanding the formation of the Hobq Desert. Here we present the stratigraphic framework of drill core DR01 with length of 2503.18 m, and the results of magnetostratigraphic and ESR dating and multi-proxy analyses of drill core WEDP05 with length of 274.60 m, from the Hetao Basin. The magnetostratigraphic and ESR results indicate that core WEDP05 spans the last ∼1.68 Ma. Stratigraphic sequence of core DR01 indicates that the Hetao area was uplifted and eroded during the early Cenozoic, before subsiding to form a sedimentary basin. Subsequently, the basin was a fluvio-lacustrine environment during the Pliocene and then experienced alternating desert and fluvio-lacustrine conditions during the Quaternary. Sedimentary facies and multi environmental-proxy analyses of core WEDP05 indicate that the basin was occupied by a fluvio-lacustrine system during the following intervals: ∼1.47 - ∼1.30 Ma, ∼1.17 - ∼1.07 Ma, ∼0.68 - ∼0.60 Ma and from ∼0.47 Ma to the last interglacial; and that a desert environment developed during the lake regression phases of ∼1.30 - ∼1.17 Ma, ∼1.07 - ∼0.68 Ma and ∼0.60 - ∼0.47 Ma. The presence of aeolian sand at the base of core WEDP05 suggests that the origin of the Hobq Desert can be traced back to the early Pleistocene, and resulted from the erosion and transportation of exposed fluvio-lacustrine sediments by near-surface winds associated with the Asian winter monsoon. A large river channel in the Hetao Basin may have existed as early as the Pliocene, which was occupied by the Yellow River when its upper reaches formed by at least ∼1.6 Ma. Subsequently, at least since ∼1.2 Ma, the Yellow River formed its drainage system around the Hetao Basin and controlled the paleoenvironment evolution of the basin.

  5. Magnetic minerals as recorders of weathering, diagenesis, and paleoclimate: A core-outcrop comparison of Paleocene-Eocene paleosols in the Bighorn Basin, WY, USA

    Science.gov (United States)

    Maxbauer, Daniel P.; Feinberg, Joshua M.; Fox, David L.; Clyde, William C.

    2016-10-01

    Magnetic minerals in paleosols hold important clues to the environmental conditions in which the original soil formed. However, efforts to quantify parameters such as mean annual precipitation (MAP) using magnetic properties are still in their infancy. Here, we test the idea that diagenetic processes and surficial weathering affect the magnetic minerals preserved in paleosols, particularly in pre-Quaternary systems that have received far less attention compared to more recent soils and paleosols. We evaluate the magnetic properties of non-loessic paleosols across the Paleocene-Eocene Thermal Maximum (a short-term global warming episode that occurred at 55.5 Ma) in the Bighorn Basin, WY. We compare data from nine paleosol layers sampled from outcrop, each of which has been exposed to surficial weathering, to the equivalent paleosols sampled from drill core, all of which are preserved below a pervasive surficial weathering front and are presumed to be unweathered. Comparisons reveal an increase in magnetization in outcrops compared with core equivalents, which is principally driven by secondary hematite production. Authigenic hematite production in outcrops presents a complication for goethite-hematite based paleoprecipitation proxies where estimates will be biased toward drier climate regimes. The occurrence of low coercivity minerals is more consistent between core and outcrop. However, we propose an alteration process for pedogenic magnetite that is observed in both core and outcrop, where pedogenic magnetite becomes progressively oxidized leading to higher mean coercivities and broader coercivity distributions compared to modern pedogenic magnetite. This combination of diagenetic processes and surface weathering influences the magnetic properties of paleosols. Despite these changes, magnetic enhancement ratios from B-horizons correlate with independent MAP estimates from geochemical proxies, which suggests that paleoprecipitation information is preserved. Future

  6. Isotopic and hydrologic responses of small, closed lakes to climate variability: Comparison of measured and modeled lake level and sediment core oxygen isotope records

    Science.gov (United States)

    Steinman, Byron A.; Abbott, Mark B.; Nelson, Daniel B.; Stansell, Nathan D.; Finney, Bruce P.; Bain, Daniel J.; Rosenmeier, Michael F.

    2013-03-01

    Simulations conducted using a coupled lake-catchment isotope mass balance model forced with continuous precipitation, temperature, and relative humidity data successfully reproduce (within uncertainty limits) long-term (i.e., multidecadal) trends in reconstructed lake surface elevations and sediment core oxygen isotope (δ18O) values at Castor Lake and Scanlon Lake, north-central Washington. Error inherent in sediment core dating methods and uncertainty in climate data contribute to differences in model reconstructed and measured short-term (i.e., sub-decadal) sediment (i.e., endogenic and/or biogenic carbonate) δ18O values, suggesting that model isotopic performance over sub-decadal time periods cannot be successfully investigated without better constrained climate data and sediment core chronologies. Model reconstructions of past lake surface elevations are consistent with estimates obtained from aerial photography. Simulation results suggest that precipitation is the strongest control on lake isotopic and hydrologic dynamics, with secondary influence by temperature and relative humidity. This model validation exercise demonstrates that lake-catchment oxygen isotope mass balance models forced with instrumental climate data can reproduce lake hydrologic and isotopic variability over multidecadal (or longer) timescales, and therefore, that such models could potentially be used for quantitative investigations of paleo-lake responses to hydroclimatic change.

  7. A new site record of the Grizzled Giant Squirrel Ratufa macroura (Pennant, 1769 in the Hosur forest division, Eastern Ghats, India and its conservation significance

    Directory of Open Access Journals (Sweden)

    N. Baskaran

    2011-06-01

    Full Text Available The Grizzled Giant Squirrel is endemic to southern India and Sri Lanka. In India it is distributed in isolated populations with less than 500 mature individuals, restricted mostly to patchy riverine habitats. We have recorded the presence of this species (minimum 14 individuals across eight locations in Hosur forest division along the Cauvery riverine forest, north of earlier reported locations in the Eastern Ghats. The documentation of this species in the study area adds to our understanding of its distribution. These squirrels are canopy dwellers, hence discontinuous forest restricts their movement and dispersal. Measures including stop auctioning Tamarindus indica fruits on large scale for commercial purpose by Forest Department, restoration of habitat, maintenance of canopy continuity, reducing anthropogenic pressure and translocating squirrels from larger populations are suggested to enhance the long-term survival of this habitat specialist, which is on the brink of local extinction in the study area. We also suggest a comprehensive population assessment of the species to reevaluate its global status.

  8. Validity of inner canthus temperature recorded by infrared thermography as a non-invasive surrogate measure for core temperature at rest, during exercise and recovery.

    Science.gov (United States)

    Fernandes, Alex Andrade; Moreira, Danilo Gomes; Brito, Ciro José; da Silva, Cristiano Diniz; Sillero-Quintana, Manuel; Pimenta, Eduardo Mendonça; Bach, Aaron J E; Garcia, Emerson Silami; Bouzas Marins, João Carlos

    2016-12-01

    Research into obtaining a fast, valid, reliable and non-invasive measure of core temperature is of interest in many disciplinary fields. Occupational and sports medicine research has attempted to determine a non-invasive proxy for core temperature particularly when access to participants is limited and thermal safety is of a concern due to protective encapsulating clothing, hot ambient environments and/or high endogenous heat production during athletic competition. This investigation aimed to determine the validity of inner canthus of the eye temperature (TEC) as an alternate non-invasive measure of intestinal core temperature (TC) during rest, exercise and post-exercise conditions. Twelve physically active males rested for 30min prior to exercise, performed 60min of aerobic exercise at 60% V̇O2max and passively recovered a further 60min post-exercise. TEC and TC were measured at 5min intervals during each condition. Mean differences between TEC and TC were 0.61°C during pre-exercise, -1.78°C during exercise and -1.00°C during post-exercise. The reliability between the methods was low in the pre-exercise (ICC=0.49 [-0.09 to 0.82]), exercise (ICC=-0.14 [-0.65 to 0.44]) and post-exercise (ICC=-0.25 [-0.70 to 0.35]) conditions. In conclusion, poor agreement was observed between the TEC values measured through IRT and TC measured through a gastrointestinal telemetry pill. Therefore, TEC is not a valid substitute measurement to gastrointestinal telemetry pill in sports and exercise science settings.

  9. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today

    OpenAIRE

    J. R. McConnell; O. J. Maselli; Sigl, M.; P. Vallelonga; Neumann, T; H. Anschütz; R. C. Bales; Curran, M.A.J.; S. B. Das; Edwards, R.; Kipfstuhl, S.; Layman, L; E. R. Thomas

    2014-01-01

    Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was a...

  10. High-resolution detrital flux and provenance records from the Lake Suigetsu (SG06/12 cores) and climate changes in Central Japan during the last deglaciation

    Science.gov (United States)

    Nagashima, K.; Nakagawa, T.; Suzuki, Y.; Tada, R.; Sugisaki, S.; Bronk Ramsey, C.; Bryant, C. L.; Staff, R.; Brauer, A.; Lamb, H.; Schlolaut, G.; Tarasov, P. E.; Gotanda, K.; Haraguchi, T.; Yonenobu, H.; Yokoyama, Y.

    2013-12-01

    Stalagmites in Chinese caves (e.g., Wang et al., 2001, 2005), loess/paleosol sequence of the Chinese Loess Plateau, and lacustrine sediments in Asian countries are favorable to monitor the past changes in East Asian monsoon and the path and intensity of the Westerly Jet. However, not much is known about these changes during the last deglaciation mostly due to the large uncertainty in the chronologies of the lacustrine and loess/paleosol sediments. Lake Suigetsu in Central Japan is known for the varved sediments which cover at least last 70 kyr. Recently, precise Age-Model is established for SG06 core based on varve counting and more than 800 radiocarbon dates (e.g., Ramsey et al., 2012; Staff et al., 2013). Here we examine the precipitation and wind-system changes in Central Japan during the last deglaciation from the flux and provenance changes of the detrital materials in the sediments of SG06 core. We reconstructed flux of detrital materials for the last glacial part of the SG06 core (1402-1810 cm interval of the SG06 composite depth) with 1 cm resolution (corresponded to 7-13 yrs) and estimated provenance of the detrital materials using color, chemical compositions (please see a poster presented by Suzuki et al), grain sizes, and electron spin resonance intensity and crystallinity of the quartz (these methods were detailed in Nagashima et al., 2007, 2011). The reconstructed flux of detrital materials are characterized by the millennial-scale increases exceeding 12 mg/cm2/yr at 16,600-14,800 and 13,700-12,800 SG062012 yr BP and short-lived (centennial to decadal) episodes of higher flux repeated more than thirty times throughout the deglaciation. The grain sizes, color, and crystallinity of quartz suggest that the content of the detrital materials increased during 16,600-14,800 SG062012 yr BP, which was mostly due to suspended particles supplied from Hasu river through Lake Mikata, that is located immediately upstream of Lake Suigetsu and trapping most of coarse

  11. Historical record of European emissions of heavy metals to the atmosphere since the 1650s from alpine snow/ice cores drilled near Monte Rosa.

    Science.gov (United States)

    Barbante, Carlo; Schwikowski, Margit; Döring, Thomas; Gäggeler, Heinz W; Schotterer, Ulrich; Tobler, Leo; van de Velde, Katja; Ferrari, Christophe; Cozzi, Giulio; Turetta, Andrea; Rosman, Kevin; Bolshov, Michael; Capodaglio, Gabriele; Cescon, Paolo; Boutron, Claude

    2004-08-01

    Cr, Cu, Zn, Co, Ni, Mo, Rh, Pd, Ag, Cd, Sb, Pt, Au, and U have been determined in clean room conditions by inductively coupled plasma sector field mass spectrometry and other analytical techniques, in various sections of two dated snow/ice cores from the high-altitude (4450 m asl) glacier saddle Colle Gnifetti, Monte Rosa massif, located in the Swiss-Italian Alps. These cores cover a 350-year time period, from 1650 to 1994. The results show highly enhanced concentrations for most metals in snow/ice dated from the second half of the 20th century, compared with concentrations in ancient ice dated from the 17th and 18th centuries. The highest increase factors from the pre-1700 period to the post-1970 period are observed for Cd (36), Zn (19), Bi (15), Cu (11), and Ni (9), confirming the importance of atmospheric pollution by heavy metals in Europe. Metal concentrations observed in Colle Gnifetti snow around 1980 appear to be quantitatively related to metal emissions from Italy, Switzerland, Germany, France, Belgium, and Austria at that time, making it possible to reconstruct past changes in metal emission in these countries during the last centuries.

  12. Records of climatic changes and volcanic events in an ice core from Central Dronning Maud Land (East Antarctica) during the past century

    Indian Academy of Sciences (India)

    V N Nijampurkar; D K Rao; H B Clausen; M K Kaul; A Chaturvedi

    2002-03-01

    The depth profiles of electrical conductance, 18O, 210Pb and cosmogenic radio isotopes 10Be and 36Cl have been measured in a 30 m ice core from east Antarctica near the Indian station, Dakshin Gangotri. Using 210Pb and 18O, the mean annual accumulation rates have been calculated to be 20 and 21 cm of ice equivalent per year during the past ∼150 years. Using these acumulation rates, the volcanic event that occurred in 1815 AD, has been identified based on electrical conductance measurements. Based on 18O measurements, the mean annual surface air temperatures (MASAT) data observed during the last 150 years indicates that the beginning of the 19th century was cooler by about 2°C than the recent past and the middle of 18th century. The fallout of cosmogenic radio isotope 10Be compares reasonably well with those obtained on other stations (73° S to 90°S) from Antarctica and higher latitudes beyond 77°N. The fallout of 36Cl calculated based on the present work agrees well with the mean global production rate estimated earlier by Lal and Peters (1967) The bomb pulse of 36Cl observed in Greenland is not observed in the present studies a result which is puzzling and needs to be studied on neighbouring ice cores from the same region.

  13. Aligning and synchronization of MIS5 proxy records from Lake Ohrid (FYROM) with independently dated Mediterranean archives: implications for DEEP core chronology

    Science.gov (United States)

    Zanchetta, Giovanni; Regattieri, Eleonora; Giaccio, Biagio; Wagner, Bernd; Sulpizio, Roberto; Francke, Alex; Vogel, Hendrik; Sadori, Laura; Masi, Alessia; Sinopoli, Gaia; Lacey, Jack H.; Leng, Melanie J.; Leicher, Niklas

    2016-05-01

    The DEEP site sediment sequence obtained during the ICDP SCOPSCO project at Lake Ohrid was dated using tephrostratigraphic information, cyclostratigraphy, and orbital tuning through the marine isotope stages (MIS) 15-1. Although this approach is suitable for the generation of a general chronological framework of the long succession, it is insufficient to resolve more detailed palaeoclimatological questions, such as leads and lags of climate events between marine and terrestrial records or between different regions. Here, we demonstrate how the use of different tie points can affect cyclostratigraphy and orbital tuning for the period between ca. 140 and 70 ka and how the results can be correlated with directly/indirectly radiometrically dated Mediterranean marine and continental proxy records. The alternative age model presented here shows consistent differences with that initially proposed by Francke et al. (2015) for the same interval, in particular at the level of the MIS6-5e transition. According to this new age model, different proxies from the DEEP site sediment record support an increase of temperatures between glacial to interglacial conditions, which is almost synchronous with a rapid increase in sea surface temperature observed in the western Mediterranean. The results show how a detailed study of independent chronological tie points is important to align different records and to highlight asynchronisms of climate events. Moreover, Francke et al. (2016) have incorporated the new chronology proposed for tephra OH-DP-0499 in the final DEEP age model. This has reduced substantially the chronological discrepancies between the DEEP site age model and the model proposed here for the last glacial-interglacial transition.

  14. Robert Recorde

    CERN Document Server

    Williams, Jack

    2011-01-01

    The 16th-Century intellectual Robert Recorde is chiefly remembered for introducing the equals sign into algebra, yet the greater significance and broader scope of his work is often overlooked. This book presents an authoritative and in-depth analysis of the man, his achievements and his historical importance. This scholarly yet accessible work examines the latest evidence on all aspects of Recorde's life, throwing new light on a character deserving of greater recognition. Topics and features: presents a concise chronology of Recorde's life; examines his published works; describes Recorde's pro

  15. Seasonally resolved ice core records from West Antarctica indicate a sea ice source of sea-salt aerosol and a biomass burning source of ammonium

    Science.gov (United States)

    Pasteris, Daniel R.; McConnell, Joseph R.; Das, Sarah B.; Criscitiello, Alison S.; Evans, Matthew J.; Maselli, Olivia J.; Sigl, Michael; Layman, Lawrence

    2014-07-01

    The sources and transport pathways of aerosol species in Antarctica remain uncertain, partly due to limited seasonally resolved data from the harsh environment. Here, we examine the seasonal cycles of major ions in three high-accumulation West Antarctic ice cores for new information regarding the origin of aerosol species. A new method for continuous acidity measurement in ice cores is exploited to provide a comprehensive, charge-balance approach to assessing the major non-sea-salt (nss) species. The average nss-anion composition is 41% sulfate (SO42-), 36% nitrate (NO3-), 15% excess-chloride (ExCl-), and 8% methanesulfonic acid (MSA). Approximately 2% of the acid-anion content is neutralized by ammonium (NH4+), and the remainder is balanced by the acidity (Acy ≈ H+ - HCO3-). The annual cycle of NO3- shows a primary peak in summer and a secondary peak in late winter/spring that are consistent with previous air and snow studies in Antarctica. The origin of these peaks remains uncertain, however, and is an area of active research. A high correlation between NH4+ and black carbon (BC) suggests that a major source of NH4+ is midlatitude biomass burning rather than marine biomass decay, as previously assumed. The annual peak in excess chloride (ExCl-) coincides with the late-winter maximum in sea ice extent. Wintertime ExCl- is correlated with offshore sea ice concentrations and inversely correlated with temperature from nearby Byrd station. These observations suggest that the winter peak in ExCl- is an expression of fractionated sea-salt aerosol and that sea ice is therefore a major source of sea-salt aerosol in the region.

  16. The Chew Bahir Drilling Project (HSPDP). Deciphering climate information from the Chew Bahir sediment cores: Towards a continuous half-million year climate record near the Omo - Turkana key palaeonanthropological Site

    Science.gov (United States)

    Foerster, Verena E.; Asrat, Asfawossen; Chapot, Melissa S.; Cohen, Andrew S.; Dean, Jonathan R.; Deino, Alan; Günter, Christina; Junginger, Annett; Lamb, Henry F.; Leng, Melanie J.; Roberts, Helen M.; Schaebitz, Frank; Trauth, Martin H.

    2017-04-01

    As a contribution towards an enhanced understanding of human-climate interactions, the Hominin Sites and Paleolakes Drilling Project (HSPDP) has successfully completed coring five dominantly lacustrine archives of climate change during the last 3.5 Ma in East Africa. All five sites in Ethiopia and Kenya are adjacent to key paleoanthropological research areas encompassing diverse milestones in human evolution, dispersal episodes, and technological innovation. The 280 m-long Chew Bahir sediment records, recovered from a tectonically-bound basin in the southern Ethiopian rift in late 2014, cover the past 550 ka of environmental history, a time period that includes the transition to the Middle Stone Age, and the origin and dispersal of modern Homo sapiens. Deciphering climate information from lake sediments is challenging, due to the complex relationship between climate parameters and sediment composition. We will present the first results in our efforts to develop a reliable climate-proxy tool box for Chew Bahir by deconvolving the relationship between sedimentological and geochemical sediment composition and strongly climate-controlled processes in the basin, such as incongruent weathering, transportation and authigenic mineral alteration. Combining our first results from the long cores with those from a pilot study of short cores taken in 2009/10 along a NW-SE transect of the basin, we have developed a hypothesis linking climate forcing and paleoenvironmental signal-formation processes in the basin. X-ray diffraction analysis of the first sample sets from the long Chew Bahir record reveals similar processes that have been recognized for the uppermost 20 m during the pilot-study of the project: the diagenetic illitization of smectites during episodes of higher alkalinity and salinity in the closed-basin lake induced by a drier climate. The precise time resolution, largely continuous record and (eventually) a detailed understanding of site specific proxy formation

  17. Proteomics Core

    Data.gov (United States)

    Federal Laboratory Consortium — Proteomics Core is the central resource for mass spectrometry based proteomics within the NHLBI. The Core staff help collaborators design proteomics experiments in a...

  18. Proteomics Core

    Data.gov (United States)

    Federal Laboratory Consortium — Proteomics Core is the central resource for mass spectrometry based proteomics within the NHLBI. The Core staff help collaborators design proteomics experiments in...

  19. A 2.8 Ma record of environmental evolution and tectonic events inferred from the Cuoe core in the middle of Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    SHEN; Ji; Lü; Houyuan; WANG; Sumin; CHEN; Shiyue; YANG; Xia

    2004-01-01

    Based on a multi-proxy investigation into the deep core of the Cuoe Lake in the middle of Tibetan Plateau, a 2.8 Ma paleoclimatic and paleoenvironmental evolution is reconstructed. The result of magnetic stratum indicates that the lake basin was formed at about 2.8 MaBP, while the multi-proxy analyses of lithology, grain size, magnetic susceptibility and geochemical elements reveal that there have been three major environmental evolution stages and at least two intensive uplifts of the Tibetan Plateau in the lake basin area, i.e. during 2.8-2.5 MaBP, the lake basin came into being as a result of the disaggregation of the planation surface and rapid rising of the Tibetan Plateau. During 2.5-0.8 MaBP, with gradual uplift of the Tibetan Plateau, the environment of this area was more effectively controlled by the climatic cycle of the alternative glacial-interglacial stages. After 0.8 MaBP, the middle part of the Plateau accelerated its uplift and entered cryoshere.

  20. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today

    DEFF Research Database (Denmark)

    McConnell, J.R.; Maselli, OJ; Sigl, Michael

    2014-01-01

    century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement...... efforts, significant lead pollution in Antarctica persists into the 21st century....

  1. Does asteroid 4 Vesta, with watery 1 Ceres and the Galilean moons, record the Ringwood-mode iron core construction now predicated for Earth and even apply to the other terrestrial planets?

    Science.gov (United States)

    Osmaston, M. F.

    2014-04-01

    I reason that Vesta, the source of HED but too small for appreciable magmatic resurfacing after accretion had ended, preserves valuable clues as to how the Earth and the other terrestrials were built. Setting the scene. Core formation in the terrestrial planets has long been attributed to the percolation of molten iron accreted from the solar nebula, either inward from the surface or from a magma ocean at depth. But it has been found [1,2] that the 56Fe/54Fe ratio in Earth peridotites still has a chondritic ratio, which rules out that Fe percolation has occurred. So we must revert now to Ringwood's model (1960-1978) e.g.[3] for core formation. This uses the nebula to reduce hot FeO in lavas erupted in volcanoes at the protoplanet's surface. The Fe, which then drains to the bottom of the magma chamber and solidifies, is subsequently 'loadsubducted' rapidly to form the core. For Earth's core alone this would generate ~400 earth-ocean volumes of reaction water, a Solar System benefit already foreseen by Ringwood, water being low in star-forming clouds. The heat for the volcanism is internal (accretion, gravitation, radiogenic) so orbital distance in the presence of nebular opacity is immaterial; and important for making the cores in the Galilean moons, otherwise labelled as being at the 'snowline' in the disc. In order to work, prior iron accretion to form the body must have been in oxide form. Thermodynamically this is correct if the nebula is cool (deep. Current flows in this, presumably below a frozen lid, appear to have carved early deep channels in the uncoherent regolith, well seen as a.m.- conserving spiral channels (5.3hr rotationperiod) outboard of the later southern impact. Circum-equatorial similar grooves all seem to predate the impact cratering, made possible by loss of the water/ice. Character of an RM volcano interior. We can construct a vertical section from the meteoritic record, with eucrites at the top, diogenites in-between, pallasites (stonyiron

  2. Grain-size Dependence and Environment Significance of Trace Elements from ZL Core in the Jianghan Basin%江汉盆地ZL钻孔微量元素含量的粒度效应与环境意义

    Institute of Scientific and Technical Information of China (English)

    袁胜元; 李长安; 邵磊

    2012-01-01

    lithophile and chalcophile elements are relatively enriched compared to the Upper Continental Crust(UCC).The siderophile elements are depleted compared with the UCC.It probably indicates that the most of the sediments of the Jianghan Basin derived from the upper Yangtze rather than the materials from the deep earth in the Yangtze block.The lacustrine sediments of the Core Zhoulao around 287m show low-Sr,and V/Ni ratios and high Zr/Sr and Rb/Sr ratios,which indicate that salt lake largely developed in the Jianghan Basin under the cold and dry weather between 2.6 ~ 2.43 Ma B.P..In contrast,freshwater lake developed around 2.1 Ma B.P..It is consistent with the late Cenozoic pollen assemblages in the Jianghan Basin,and the sedimentary records in the Subei Basin and Yangtze delta.We conclude that the elemental compositions in the Jianghan Basin might record the global cooling around 2.5 Ma B.P.and the intense uplift of the Tibetan Plateau around 1.4~1.2 Ma B.P.%江汉盆地是长江出三峡后第一个大型卸载区,近2.77 Ma以来堆积了近300 m的碎屑沉积物,主要由河流相和湖沼相组成,形成了多个沉积旋回。选择江汉盆地中心位置的ZL钻孔,利用ICP—MS方法展开微量元素组成分析,细粒组分中微量元素含量与各粒组含量相关性并不明显,主要是5~7粒级组分表现出微弱的相关性.可见,粒度并非ZL钻孔微量元素丰度的主控因素。钻孔岩心中大部分亲石元素、亲硫元素相对上部陆壳均出现明显富集,亲铁元素总体低于上部陆壳,可能与江汉盆地总体上更多地接受了来自上游而非扬子古陆本地深源物质风化碎屑沉积有关。Sr、V/Ni和Sr/Ba值的变化则表明江汉盆地在2.6~2.43 Ma B.P.时可能有咸化湖的发育,而在2.1 Ma B.P.左右存在过一段大湖发育期。

  3. Significant Collisions

    Institute of Scientific and Technical Information of China (English)

    YIN PUMIN

    2010-01-01

    @@ Two beams of subatomic particles,called hadrons, either protons or lead ions, successfully collided at the record-high energy level of 7 tril-lion electron volts, inside the Large Hadron Collider (LHC), the world's largest and most powerful particle accelerator, on March 30, 2010, as part of an experiment aimed at uncovering the origins of the universe.

  4. Using the significant dust deposition event on the glaciers of Mt. Elbrus, Caucasus Mountains, Russia on 5 May 2009 to develop a method for dating and provenancing of desert dust events recorded in snow pack

    Directory of Open Access Journals (Sweden)

    M. Shahgedanova

    2012-09-01

    Full Text Available A significant desert dust deposition event occurred on Mt. Elbrus, Caucasus Mountains, Russia on 5 May 2009, where the deposited dust later appeared as a brown layer in the snow pack. An examination of dust transportation history and analysis of chemical and physical properties of the deposited dust were used to develop a new approach for high-resolution provenancing of dust deposition events recorded in snow pack using multiple independent techniques. A combination of SEVIRI red-green-blue composite imagery, MODIS atmospheric optical depth fields derived using the Deep Blue algorithm, air mass trajectories derived with HYSPLIT model and analysis of meteorological data enabled identification of dust source regions with high temporal (hours and spatial (ca. 100 km resolution. Dust, deposited on 5 May 2009, originated in the foothills of the Djebel Akhdar in eastern Libya where dust sources were activated by the intrusion of cold air from the Mediterranean Sea and Saharan low pressure system and transported to the Caucasus along the eastern Mediterranean coast, Syria and Turkey. Particles with an average diameter below 8 μm accounted for 90% of the measured particles in the sample with a mean of 3.58 μm, median 2.48 μm and the dominant mode of 0.60 μm. The chemical signature of this long-travelled dust was significantly different from the locally-produced dust and close to that of soils collected in a palaeolake in the source region, in concentrations of hematite and oxides of aluminium, manganese, and magnesium. Potential addition of dust from a secondary source in northern Mesopotamia introduced uncertainty in the provenancing of dust from this event. Nevertheless, the approach adopted here enables other dust horizons in the snowpack to be linked to specific dust transport events recorded in remote sensing and meteorological data archives.

  5. Influence of regional precipitation patterns on stable isotopes in ice cores from the central Himalayas

    Directory of Open Access Journals (Sweden)

    H. Pang

    2013-05-01

    Full Text Available Several ice cores have been recovered from the Dasuopu Glacier and the East Rongbuk (ER Glacier in the central Himalayas since the 1990s. Although the distance between the ER and the Dasuopu ice core drilling sites is only ∼125 km, the stable isotopic record (δ18O or δD of the ER core is interpreted as a precipitation proxy while the Dasuopu core as a temperature proxy. Thus, the climatological significance of the stable isotopic records of these Himalayan ice cores remains a subject of debate. Based on analysis of regional precipitation patterns over the region, we find that the different interpretations of the Dasuopu and Everest isotopic records may not be contradictive. The north–south and west–east seesaws of the Indian Summer Monsoon (ISM precipitation are primarily responsible for precipitation falling at the ER site, which results in a negative correlation between the ER δ18O or δD record and precipitation amount along the southern slope of the central Himalayas, corresponding to the "amount effect". In addition to the ISM precipitation, non-summer monsoonal precipitation associated with winter westerlies also significantly contributes to precipitation falling at the Dasuopu site, which may cause a positive correlation between the Dasuopu stable isotopic record and temperature, in response to the "temperature effect". Our results have important implications for interpreting the stable isotopic ice core records recovered from different climatological regimes of the Himalayas.

  6. δ18O record of the Miaoergou ice core from the Karlik mountains of east Tienshan since 1953%天山东部哈尔里克山庙儿沟冰芯1953年以来的δ18O记录

    Institute of Scientific and Technical Information of China (English)

    宋琳琳; 侯书贵; 刘亚平

    2011-01-01

    2005年8月在天山东部哈尔里克山庙儿沟平顶冰川顶部钻取了两只透底冰芯,其中一支冰芯定年结果为16.83 m,深度对应1953年.着重探讨了沉积过程和沉积后过程对该冰芯氧同位素比率(δ18O)记录的可能影响及该冰芯1953年以来δ18O记录的气候指示意义.降水季节分布的不均匀性、夏季高温引起的融化-渗浸-再冻结作用,以及冬季雪层中的水汽运移和积雪表面的升华可能在一定程度上影响了冰芯δ18O记录,但考察时观测表明当年降雪仍约有50 cm剩余,且δ18O与Ca2+的季节波动保存较好,表明沉积过程和沉积后过程对于δ18O的影响范围局限于年层内.1953-2004年庙儿沟冰芯δ18O记录呈线性下降趋势,与同处哈尔里克山南坡的哈密气象站夏季温度的长期变化趋势一致,二者存在明显的正相关关系,庙儿沟冰芯δ18O记录可作为该区域过去夏季温度变化的代用指标.%Two ice cores were drilled to bed-rock at the Miaoergou flat-topped glacier in Karlik mountains, eastern Tienshan, in August 2005. The upper part of one of the two ice cores was dated as 1953 at the depth of 16.83 m. This paper focused on the probable depositional and post-depositional effects on the stable oxygen isotope ratios (σ18O) of the ice core, and its climatic significance since 1953. The ice core σ18O record was somewhat modified by the seasonal precipitation distribution and melt-infiltration-refreezing processes due to high summer temperature, moisture exchange between firn layers and sublimation at snow surface in winter. Nonetheless, it can be inferred that the influence of depositional and post-depositional processes on isotopic record was limited, because the seasonal fluctuation of Ca2+and σ18O was apparently preserved, and about 50 cm snow of that very year is still visible. During the period of 1953-2004, the linear trend of Miaoergou σ18O was descending, which was consistent with the trend of

  7. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad

    2010-01-01

    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  8. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad

    2008-01-01

    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  9. Record of Lacquering as Core of the System of Eastern Asian Lacquer Art-- On Record of Lacquering and Lacquer Art in Eastern Asia%建构以《髹饰录》为核心的东亚漆艺体系--读《与东亚漆艺--传统髹饰工艺体系研究》

    Institute of Scientific and Technical Information of China (English)

    何振纪

    2015-01-01

    将东亚地区作为一个艺术研究的范畴,早在19世纪末20世纪初就已风行一时,却因20世纪社会文化对国族概念的迷恋,导致这方面的研究逐渐被以国家为基础的民族艺术研究所掩盖。长北教授《与东亚漆艺——传统髹饰工艺体系研究》一书以东亚艺术史研究的宏观视野探索东亚漆艺的发展嬗变,通过对古代漆艺经典《髹饰录》的解读以及对东亚诸国漆艺历史与现状的分析比较,清晰地归纳出了以中华漆艺为本源的东亚漆艺发生衍变脉络,勾勒出了东亚漆工艺体系的恢宏图景。%Between 19th and 20th centuries, the concept Eastern Asia was popular in the research of oriental art history, but was declining during the 20th century when the rise of the idea on national art history. Today, Pro. Changbei with the topic of lacquer art returned into the Eastern Asia art history view. In her new work Record of Lacquering and Lacquer Art in Eastern Asia, Changbei explained the classic lacquering text Xiushilu (Record of Lacquering) again, and analyzed and compared the record of it with the lacquer art in the different countries of Eastern Asia. By this way, Changbei concluded a context with Xiushilu as a core of the Eastern Asia lacquer art’s development.

  10. Electrical conductivity measurements from the GISP2 and GRIP Greenland ice cores

    DEFF Research Database (Denmark)

    Dahl-Jensen, Dorthe; Clausen, Henrik Brink; Taylor, K. C.

    1993-01-01

    . Here we present electrical conductivity records for the Greenland Ice Sheet Project 2 (GISP2) and Greenland Ice-core Project (GRIP) ice cores, drilled 28 km apart to enable direct comparison of the results. The upper parts of both records are consistent with previous evidence from other Greenland cores......THE direct-current electrical conductivity of glacial ice depends on its acidity1-3, and can also indicate changes in climate, as ice formed in cold, dusty periods has a high concentration of alkaline dust1,4,5, which significantly reduces the conductivity6,7 compared to warmer, less dusty periods......4,8& #150;12 for a stable Greenland climate during the Holocene, and a series of warm events punctuating the last glacial period. However, there is a significant discrepancy between the two records in the bottom 10% of the cores, calling into question recent reports of climate variability...

  11. In vitro evaluation of the fracture strength of all-ceramic core materials on zirconium posts.

    Science.gov (United States)

    Ozcan, Nihal; Sahin, Erdal

    2013-10-01

    For most endodontically treated teeth, tooth-colored post-core systems are preferable for esthetic reasons. Therefore, improvements in material strength must also consider tooth colored post-core complexes. The objective of this study was to evaluate the difference in tooth colored post-core complex strengths. A total of 33 human maxillary central incisor teeth were used for this study, with three groups of 11 teeth. Three different methods were used to fabricate all-ceramic post-core restorations: zirconia blanks, Cerec 3D-milled to one-piece post-core restorations (Test Group 1); feldspathic cores (from feldspathic prefabricated CAD/CAM blocks) adhesively luted to CosmoPost zirconia posts (Test Group 2); and IPS Empress cores directly pressed to CosmoPost zirconia posts (Test Group 3). All-ceramic crowns from feldspathic ceramic were constructed using a CAD/CAM system (Cerec 3D) for all specimens. The post-core complexes were tested to failure with the load applied at 45° angled relative to the tooth long axis. The load at fracture was recorded. The maximum fracture strength of the milled zirconia cores (Test Group 1) was 577 N; corresponding values for the milled feldspathic cores (Test Group 2) and the pressed cores (Test Group 3) were 586 and 585 N, respectively. Differences were not statistically significant at P cores adhesively luted on zirconia posts and one-piece all-ceramic zirconium post-core structures offer a viable alternative to conventional pressing.

  12. 丙型肝炎核心抗原检测在丙型肝炎诊断中的意义%Detection of HCV core antigen and its diagnostic significance

    Institute of Scientific and Technical Information of China (English)

    杨杰; 崔敬; 刘春; 魏枫华; 窦晓光

    2013-01-01

    目的 了解丙型肝炎核心抗原(HCV-cAg)检测方法的敏感性及特异性,确定具有临床意义的S/CO值,探讨其在丙型肝炎诊断中的意义.方法 使用ELASA方法检测丙型肝炎核心抗原,RT-PCR检测HCV RNA定量,观察不同S/CO值所对应的HCV RNA定量之间的关系,以HCV RNA为诊断金标准,列四格表做诊断实验.结果 HCV-cAg抗原检测的敏感性为87.05%,特异性为76.67%,阳性预测值为96.53%,阴性预测值为44.23%.结论 (1)随着HCV-cAg的S/CO值逐渐增大,其与HCV RNA阳性符合率明显增高,随着HCV-cAg的S/CO值减小,其与HCV RNA阴性符合率明显增高;(2)S/CO值=2可以作为临床判断HCV感染病毒血症存在的一个标准;(3)本实验的敏感性和特异性较好,检测方法简单,可以作为丙型肝炎临床诊断的补充试验及筛查.%Objective To compare the abilities of the hepatitis C virus (HCV) core antigen (cAg) test and the HCV RNA assay for confirming anti - HCV presence in order to determine the clinical utility of the HCV - cAg as an alternative or confirmatory diagnostic tool. Methods Serum samples collected from 158 patients diagnosed with HCV infection were subjected to the enzyme - linked immunosorbent assay - based HCV — cAg test. The optical density ( OD) measured values were used to calculate the ratio of specimen absorbance to the cutoff value (S/ CO). Simultaneously, the serum samples were subjected to PCR - based nucleic acid amplification quantitative fluorescence detection of HCV RNA. Results None of the serum samples had a S/CO value 5 ( 100% positive). The HCV - cAg test sensitivity was 87. 05% , specificity was 76. 67% , positive predictive value was 96. 53% , and negative predictive value was 44. 23% . As the S/CO value gradually increased, the significantly higher positive coincident rate of the HCV RNA test decreased. The HCV RNA negative coincident rate was significantly higher than that of the HCV - cAg test. HCV - cAg S/CO values

  13. Dinoflagellate Cysts Records from Core Samples of Modern Marine Sediment at the Luoyuan Bay Mouth%罗源湾口柱状沉积物中的甲藻孢囊

    Institute of Scientific and Technical Information of China (English)

    孙爱梅; 李超; 蓝东兆; 祝跃

    2007-01-01

    Thirty species of dinoflagellate cysts in 15 genus are identified from KMZK5 Core samples of recent marine sediment at the Luoyuan Bay mouth, Fujian. All of these dinoflagellate cysts are first recorded in the Luyuan Bay, 12 species of them are not distributing in the near sea area such as Sansha Bay and Minjiang estuary, including 6 kinds of toxic species, such as Alexandrium affine,A. minutum, A. tamarense, Gonyaulax spinifera, Gymnodinium catenatum and Scrippsiella trochoidea. The abundance and vertical distribution characterestics of the main and the toxic dinoflgellate cysts are also studied in the paper.%通过对福建罗源湾口海域 KMZK5 柱状沉积物中甲藻孢囊的分析,共鉴定出 15 属 30 种甲藻孢囊.对比发现这 30 种甲藻孢囊是该湾以前未被记录的种类.其中 12 种是附近海域也未曾发现的种类,6 种为有毒种类:缘亚历山大藻、小型亚历山大藻、塔玛亚历山大藻、具刺膝沟藻、链状裸甲藻、锥状斯氏藻.同时对甲藻孢囊的主要属种和有毒种类的丰度、分布在垂直方向上的变化特征进行了初步研究.

  14. Mercury's core evolution

    Science.gov (United States)

    Deproost, Marie-Hélène; Rivoldini, Attilio; Van Hoolst, Tim

    2016-10-01

    Remote sensing data of Mercury's surface by MESSENGER indicate that Mercury formed under reducing conditions. As a consequence, silicon is likely the main light element in the core together with a possible small fraction of sulfur. Compared to sulfur, which does almost not partition into solid iron at Mercury's core conditions and strongly decreases the melting temperature, silicon partitions almost equally well between solid and liquid iron and is not very effective at reducing the melting temperature of iron. Silicon as the major light element constituent instead of sulfur therefore implies a significantly higher core liquidus temperature and a decrease in the vigor of compositional convection generated by the release of light elements upon inner core formation.Due to the immiscibility in liquid Fe-Si-S at low pressure (below 15 GPa), the core might also not be homogeneous and consist of an inner S-poor Fe-Si core below a thinner Si-poor Fe-S layer. Here, we study the consequences of a silicon-rich core and the effect of the blanketing Fe-S layer on the thermal evolution of Mercury's core and on the generation of a magnetic field.

  15. Core BPEL

    DEFF Research Database (Denmark)

    Hallwyl, Tim; Højsgaard, Espen

    extensions. Combined with the fact that the language definition does not provide a formal semantics, it is an arduous task to work formally with the language (e.g. to give an implementation). In this paper we identify a core subset of the language, called Core BPEL, which has fewer and simpler constructs......, does not allow omissions, and does not contain ignorable elements. We do so by identifying syntactic sugar, including default values, and ignorable elements in WS-BPEL. The analysis results in a translation from the full language to the core subset. Thus, we reduce the effort needed for working...... formally with WS-BPEL, as one, without loss of generality, need only consider the much simpler Core BPEL. This report may also be viewed as an addendum to the WS-BPEL standard specification, which clarifies the WS-BPEL syntax and presents the essential elements of the language in a more concise way...

  16. Core BPEL

    DEFF Research Database (Denmark)

    Hallwyl, Tim; Højsgaard, Espen

    extensions. Combined with the fact that the language definition does not provide a formal semantics, it is an arduous task to work formally with the language (e.g. to give an implementation). In this paper we identify a core subset of the language, called Core BPEL, which has fewer and simpler constructs......, does not allow omissions, and does not contain ignorable elements. We do so by identifying syntactic sugar, including default values, and ignorable elements in WS-BPEL. The analysis results in a translation from the full language to the core subset. Thus, we reduce the effort needed for working...... formally with WS-BPEL, as one, without loss of generality, need only consider the much simpler Core BPEL. This report may also be viewed as an addendum to the WS-BPEL standard specification, which clarifies the WS-BPEL syntax and presents the essential elements of the language in a more concise way...

  17. The impact of core length on prostate cancer diagnosis during a standard 14-core prostate biopsy scheme.

    Science.gov (United States)

    Dell'Atti, Lucio; Ippolito, Carmelo

    2016-11-18

    Even if many studies in the literature purposed to evaluate the improvement of the prostate biopsy (PBx), few studies assessed the diagnostic value of core length in PBx. In this study, we evaluated the length of needle cores sampled during transrectal PBx (TRUSBx) and its impact on cancer diagnosis in a standard 14-core scheme. Medical records of 573 patients who underwent an initial TRUSBx with 14-cores scheme for suspicious prostate cancer (PCa) at our Department were reviewed. The PBx procedure and pathological evaluation were standardized. Cores lengths were compared in patients with versus without cancer, and were divided into group A and B, respectively. Statistical analysis was done to define an acceptable cut-off for biopsy length. The mean age of the entire cohort was 62.1 ± 7.2 years, while median total prostate-specific antigen (PSA) and prostate volume were 4.2 ng/ml and 44.7 ml, respectively. PCa was showed in 33.3% of patients. Mean core length in group A versus B was 11.9 ± 3.9 versus 11.1 ± 3.2 mm (p = 0.016). Thus, core lengths were significantly longer in patients with cancer. There were no statistically significant differences when we considered the whole length of cores sampled from the right lobe (p = 0.58) and left lobe (p = 0.34). The cancer detection rates in cores may be increased by core length in PCa patients during a TRUSBx. Our results suggest a core length of greater than 11.8 mm as a cut-off for quality warranty.

  18. Advances in core drilling technology

    Science.gov (United States)

    Holdsworth, G.

    Some notable technical advances in drill design were reported at the meeting, held in Canada August 30-September 1, 1982, at the University of Calgary. Chief amongst these was a battery powered, computer assisted electromechanical core drill which has recently been used by the Danes in Greenland to continuously core to the base of the ice sheet at 2038 m. This is the deepest coring operation so far on the Greenland ice sheet. (The record for deep glacier drilling is held by the U.S. Army Cold Regions Research and Engineering Laboratory for the continuous coring through 2164 m of ice to bedrock at Byrd Station, Antarctica, in 1968). In early 1982, a current Soviet core drilling operation was reported to be at a depth of 2000 m at Vostok station, Antarctica, where the total ice thickness is about 4000 m; the goal of core drilling the entire ice thickness there could be achieved before the end of 1983.

  19. Abrupt climatic changes on the Tibetan Plateau during the Last Ice Age——Comparative study of the Guliya ice core with the Greenland GRIP ice core

    Institute of Scientific and Technical Information of China (English)

    姚檀栋

    1999-01-01

    Based on a comparative study of the Gtdiya ice core with the Greenland GRIP ice core, the abrupt climatic changes on the Tibetan Plateau during the Last Ice Age have been examined. The major stadial-interstadial events and 7 warm events (BrΦrump, Odderade, Oerel, Glinde, Hengelo, Denekamp, BΦlling) are consistent in the two ice cores. However, there are some unique features in the Guliya ice core records. The transition from warm to cold periods in the Guliya ice core is faster than that in the Greenland GRIP ice core. The magnitude of the climatic changes in the Guliya ice core is also larger than that in the Greenland GRIP ice core. Another significant feature of the Guliya ice core records is that there is a series of cycles of about 200 a from 18 to 35 kaBP. 22 warm events and 20 cold events with a fluctuation magnitude of 7℃ have been distinguished. The warm and cold events with a fluctuation magnitude within 3℃ are as high as 100. It is speculated that the abrupt climatic changes in different

  20. 论《史记论文》的评点成就及其批评史意义%A Research in the Achievements and Historical Significance of Comments on Historical Records

    Institute of Scientific and Technical Information of China (English)

    闫娜

    2014-01-01

    《史记论文》初刻于康熙二十五年,是清代第一部《史记》评点专著。《史记论文》指出:《史记》叙事或有虚构成分,节奏多变;《史记》写人注重轶事生色,语言富有个性化,角度多变。《史记论文》的评点,突破了传统史学话语的桎梏,彰显了《史记》的文学意义;《史记论文》的评点,借鉴了金圣叹在小说和《史记》方面的评点成就,突破了明代《史记》评点以章法、句法、字法为核心的分析范式,为后代的《史记》评点和批评奠定了基础。%Comments on Historical Records, pressed in the twenty fifth years in Kang Xi period of the Qing dynasty, is the first monograph in comments of Historical Records among the Qin dynasty.Comments on Historical Records put forward that there are some fictions in Historical Records and that the plots of Historical Records are varied;it also points that by writing some trivia and personalized language, Historical Records successfully portrays the characters.Comments on Historical Records introduced and re-constructed the category created by Jing Shentan in the comments of Historical Records and fiction, which is a breakthrough,con-structed in the Min dynasty and lays the foundation of the comments on Historical Records in the later .

  1. Records Management

    Data.gov (United States)

    U.S. Environmental Protection Agency — All Federal Agencies are required to prescribe an appropriate records maintenance program so that complete records are filed or otherwise preserved, records can be...

  2. Enhancing core-diffracted arrivals by supervirtual interferometry

    KAUST Repository

    Bharadwaj, P.

    2013-12-03

    A supervirtual interferometry (SVI) method is presented that can enhance the signal-to-noise ratio (SNR) of core diffracted waveforms by as much as O( √ N), where N is the number of inline receivers that record the core-mantle boundary (CMB) diffractions from more than one event. Here, the events are chosen to be approximately inline with the receivers along the same great circle. Results with synthetic and teleseismic data recorded by USArray stations demonstrate that formerly unusable records with low SNR can be transformed to high SNR records with clearly visible CMB diffractions. Another benefit is that SVI allows for the recording of a virtual earthquake at stations not deployed during the time of the earthquake. This means that portable arrays such as USArray can extend the aperture of one recorded earthquake from the West coast to the East coast, even though the teleseism might have only been recorded during theWest coast deployment. In summary, SVI applied to teleseismic data can significantly enlarge the catalogue of usable records both in SNR and available aperture for analysing CMB diffractions. A potential drawback of this method is that it generally provides the correct kinematics of CMB diffractions, but does not necessarily preserve correct amplitude information. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.

  3. 超声引导下粗针组织活检对甲状腺结节诊断的意义%Significance of Ultrasound-Guided Core Needle Biopsy in Diagnosis of Thyroid Nodules

    Institute of Scientific and Technical Information of China (English)

    张广; 边学海; 张纯海; 付言涛; 赵涛; 孙辉

    2011-01-01

    目的 探讨超声引导下粗针组织活检(CNB)对甲状腺结节诊断的价值.方法 回顾性分析347例甲状腺结节患者的临床资料,对患者超声引导下CNB及术后石蜡病理学结果进行比较.结果 所有患者均穿刺成功,活检取材满意度为100%;2例出现穿刺后局部血肿,经保守治疗后缓解.347例患者CNB病理学结果显示:117例考虑为恶性,其中115例为甲状腺乳头状癌,1例为未分化腺癌,1例为鳞癌;230例考虑为良性,其中53例为甲状腺炎,141例为结节性甲状腺肿,16例为甲状腺腺瘤,20例为结节性甲状腺肿合并甲状腺炎.132例行手术治疗(113例穿刺病理学结果为恶性,19例穿刺病理学结果为良性),其中127例穿刺病理学结果与术后石蜡病理学结果相符,5例为假阴性.132例手术患者中,结节直径≤0.5 cm者4例,0.5~1 cm者59例,1~2 cm者46例,>2 cm者23例,其穿刺病理学结果准确率分别为75.0%(3/4)、98.3%(58/59)、97.8%(45/46)和91.3%(21/23),提示结节直径在0.5~2 cm者穿刺病理学结果符合率最高.超声引导下CNB对甲状腺结节良、恶性鉴别诊断的准确率、敏感性、特异性、阳性预测值、阴性预测值、漏诊率和误诊率分别为96.21%(127/132)、95.76%(113/118)、100%(14/14)、100%(113/113)、0.74(14/19)、4.24%(5/118)和0(0/14).结论 超声引导下CNB对甲状腺结节具有很高的鉴别诊断价值,对甲状腺结节的治疗有重要的指导意义.%Objective To explore the value of ultrasound-guided core needle biopsy (CNB) in diagnosis of thyroid nodules. Methods The clinical data of 347 patients with thyroid nodules who underwent ultrasound-guided CNB were retrospectively analyzed, and the results of CNB pathology were compared with postoperative wax pathology results. Results All patients completed CNB successfully and satisfaction rate for tissue samples was 100%.After CNB, local hematoma occurred in two cases and relieved by conservative therapy. The CNB

  4. 喜马拉雅地区纳木那尼的化学离子特征%Glaciochemical records from Naimona'Nyi ice core in the Himalayas

    Institute of Scientific and Technical Information of China (English)

    刘勇勤; 姚檀栋; 田立德

    2006-01-01

    A 6-m ice core was recovered in 2004 from the Naimona'Nyi Glacier, the middle Himalayas. Empirical orthogonal function (EOF) analysis on the major ion reveals that EOF1 represents the variations of majority of ions which may be originated from crustal aerosols. Comparing the calcium concentrations from the Naimona'Nyi with these from Dasuopu, East Rongbuk and Guliya ice cores, it is observed that calcium, a good indicator of the input of crustal aerosol in snow, concentrates mostly in the Guliya ice core located on the northern Tibetan Plateau, and gradually decreases from west to east in the Himalayas.

  5. Clinical value of core length in contemporary multicore prostate biopsy.

    Science.gov (United States)

    Lee, Sangchul; Jeong, Seong Jin; Hwang, Sung Il; Hong, Sung Kyu; Lee, Hak Jong; Byun, Seok Soo; Choe, Gheeyoung; Lee, Sang Eun

    2015-01-01

    There is little data about the clinical value of core length for prostate biopsy (PBx). We investigated the clinical values of various clinicopathological biopsy-related parameters, including core length, in the contemporary multi-core PBx. Medical records of 5,243 consecutive patients who received PBx at our institution were reviewed. Among them, 3,479 patients with prostate-specific antigen (PSA) ≤ 10 ng/ml level who received transrectal ultrasound (TRUS)-guided multi (≥ 12)-core PBx at our institution were analyzed for prostate cancer (PCa). Gleason score upgrading (GSU) was analyzed in 339 patients who were diagnosed with low-risk PCa and received radical prostatectomy. Multivariate logistic regression analyses for PCa detection and prediction of GSU were performed. The mean age and PSA of the entire cohort were 63.5 years and 5.4 ng/ml, respectively. The overall cancer detection rate was 28.5%. There was no statistical difference in core length between patients diagnosed with PCa and those without PCa (16.1 ± 1.8 vs 16.1 ± 1.9 mm, P = 0.945). The core length was also not significantly different (16.4 ± 1.7 vs 16.4 ± 1.6mm, P = 0.889) between the GSU group and non-GSU group. Multivariate logistic regression analyses demonstrated that the core length of PBx did not affect PCa detection in TRUS-guided multi-core PBx (P = 0.923) and was not prognostic for GSU in patients with low-risk PCa (P = 0.356). In patients undergoing contemporary multi-core PBx, core length may not have significant impact on PCa detection and also GSU following radical prostatectomy among low-risk PCa group.

  6. VALIDATION OF TWO CLINICAL MEASURES OF CORE STABILITY.

    Science.gov (United States)

    Butowicz, Courtney M; Ebaugh, D David; Noehren, Brian; Silfies, Sheri P

    2016-02-01

    Emerging evidence suggests poor core stability is a risk factor for low back and lower extremity injuries in athletes. Recently the trunk stability test (TST) and unilateral hip bridge endurance test (UHBE) were developed to clinically assess core stability. Although these and other clinical tests of core stability exist, how well they assess core stability when compared to biomechanical measures of isolated core stability has not been thoroughly evaluated. The purposes of this study were to 1) determine concurrent validity of two novel clinical core stability assessments (TST and UHBE), and 2) assess relationships between these assessments and the trunk endurance and Y-Balance tests. The authors' hypothesized that the TST and UHBE would be highly correlated to the lab-based biomechanical measure of isolated core stability. Also, the TST and UHBE would be moderately correlated with each other, but not with the trunk extensor endurance and Y-Balance. Cross-Sectional design. Twenty healthy active individuals completed the TST (recorded number of errors), UHBE (s), trunk extensor endurance (s), Y-Balance (% leg length) test (YBT), and biomechanical test of core stability. Correlational analyses revealed a small, non-significant association between TST and biomechanical measures (rs = 0.2 - 0.22), while a moderate, significant relationship existed between UHBE and biomechanical measures (rs = -0.49 to -0.56, p core stability. The poor relationship between the TST and biomechanical measures, combined with observation of most control faults occurring in the lower extremity (LE) suggest the TST may not be an appropriate clinical test of core stability. Level 3.

  7. Clinical value of core length in contemporary multicore prostate biopsy.

    Directory of Open Access Journals (Sweden)

    Sangchul Lee

    Full Text Available There is little data about the clinical value of core length for prostate biopsy (PBx. We investigated the clinical values of various clinicopathological biopsy-related parameters, including core length, in the contemporary multi-core PBx.Medical records of 5,243 consecutive patients who received PBx at our institution were reviewed. Among them, 3,479 patients with prostate-specific antigen (PSA ≤ 10 ng/ml level who received transrectal ultrasound (TRUS-guided multi (≥ 12-core PBx at our institution were analyzed for prostate cancer (PCa. Gleason score upgrading (GSU was analyzed in 339 patients who were diagnosed with low-risk PCa and received radical prostatectomy. Multivariate logistic regression analyses for PCa detection and prediction of GSU were performed.The mean age and PSA of the entire cohort were 63.5 years and 5.4 ng/ml, respectively. The overall cancer detection rate was 28.5%. There was no statistical difference in core length between patients diagnosed with PCa and those without PCa (16.1 ± 1.8 vs 16.1 ± 1.9 mm, P = 0.945. The core length was also not significantly different (16.4 ± 1.7 vs 16.4 ± 1.6mm, P = 0.889 between the GSU group and non-GSU group. Multivariate logistic regression analyses demonstrated that the core length of PBx did not affect PCa detection in TRUS-guided multi-core PBx (P = 0.923 and was not prognostic for GSU in patients with low-risk PCa (P = 0.356.In patients undergoing contemporary multi-core PBx, core length may not have significant impact on PCa detection and also GSU following radical prostatectomy among low-risk PCa group.

  8. Towards a new common Greenland Ice Core Chronology for the last 5000 years

    Science.gov (United States)

    Winstrup, Mai; Olander Rasmussen, Sune; Møllesøe Vinther, Bo; Cook, Eliza; Svensson, Anders; McConnell, Joe; Steffensen, Jørgen Peder

    2017-04-01

    Since the development of the Greenland Ice Core Chronology 2005 (GICC05), it has been widely used as a reference chronology in paleoclimate research. However, recent research (Sigl et al, 2015) demonstrated that this timescale has small, but significant, issues over historical time. These discrepancies was found by counting annual layers in high-resolution chemistry records from the NEEM S1 shallow core, and confirmed by linking via 10Be marker horizons to the layer-counted WAIS Divide ice core, Antarctica, and accurately-dated tree-ring series. This work showed that a revision of GICC05 is required prior to 1250AD. We here refine and extend this work. Layer-counting in a single core will always involve some uncertainty, and we hence use data from multiple Greenland ice cores, for which high-resolution impurity records recently have been measured. These ice cores have been synchronized using volcanic marker horizons, and the layer-counting is performed automatically using the StratiCounter algorithm (Winstrup et al, 2012), while ensuring that the number of layers between volcanic horizons are the same in all cores. Based on this extended multiple-core data set, we are further able to extend the new Greenland timescale another few thousand years back in time. This will, among others, provide a new ice-core date for the catastrophic volcanic eruption ( 1600 BC) that destroyed the Greek Minoan culture, an important time marker in Greek history.

  9. lnfusing Core Socialist Values into Student Aid:Significance and Method%社会主义核心价值观融入大学生资助工作的意义与途径

    Institute of Scientific and Technical Information of China (English)

    王传辉; 张铮

    2015-01-01

    To foster and fulfill the core socialist values,colleges and universities must infuse the values into specific aspects of the student aid work so they can play a guiding role.In order for student aid to be more scientific and effective,colleges and universities need to innovate their student aid work pat-tern,take full advantage of ideological and political education and build a special student aid work team.%以社会主义核心价值观引领高校学生资助工作是培育和践行社会主义核心价值观的基本要求。高校应将社会主义核心价值观融入学生资助工作的具体环节,通过创新资助工作模式,利用思想政治教育的资源优势,建立健全高校资助工作专职化队伍等多条途径促进学生资助工作更加科学有效地开展。

  10. Clinical significance of monitoring hepatitis B virus core-related antigens%乙型肝炎病毒核心相关抗原的监测及临床意义

    Institute of Scientific and Technical Information of China (English)

    刘成; 慕永平; 杨宗国; 陈晓蓉

    2012-01-01

    Antiviral nucleot( s) ide analogs are the common therapy for patients with chronic hepatitis B ( CHB) infection. HBV DNA in peripheral blood is a sufficient and convenient indicator of treatment response and resistance; however, intrahepatic HBV DNA and covalently closed circular (ccc) DNA are superior indicators of treatment failure at earlier stages. Unfortunately, monitoring of intrahepatic nucleic acids, including HBV DNA, cccDNA and RNA, is complicated and expensive. Since serum levels of hepatitis B virus core -related antigen ( HBcrAg) correlate well with intrahepatic levels of HBV cccDNA it may represent an accurate and convenient indicator of treatment response and resistance in CHB patients. In this review, we discuss the recent research efforts to develop strategies for HBcrAg monitoring and to define the underlying mechanisms of this clinical indicator system. Besides its promising clinical value, large - scale dynamic measures of HBcrAg in CHB patients may provide useful insights into the risk and causative factors of resistance to antiviral nucleot(s) analoge therapy.%监测乙型肝炎病毒核心相关抗原(HBcrAg),能有效预测核苷(酸)类药物抗病毒治疗后产生的病毒学反弹及耐药风险,具有重要的临床实用价值.

  11. Core Java

    CERN Document Server

    Horstmann, Cay S

    2013-01-01

    Fully updated to reflect Java SE 7 language changes, Core Java™, Volume I—Fundamentals, Ninth Edition, is the definitive guide to the Java platform. Designed for serious programmers, this reliable, unbiased, no-nonsense tutorial illuminates key Java language and library features with thoroughly tested code examples. As in previous editions, all code is easy to understand, reflects modern best practices, and is specifically designed to help jumpstart your projects. Volume I quickly brings you up-to-speed on Java SE 7 core language enhancements, including the diamond operator, improved resource handling, and catching of multiple exceptions. All of the code examples have been updated to reflect these enhancements, and complete descriptions of new SE 7 features are integrated with insightful explanations of fundamental Java concepts.

  12. Models of the earth's core

    Science.gov (United States)

    Stevenson, D. J.

    1981-01-01

    Combined inferences from seismology, high-pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to models of the earth's core with five basic properties. These are that core formation was contemporaneous with earth accretion; the core is not in chemical equilibrium with the mantle; the outer core is a fluid iron alloy containing significant quantities of lighter elements and is probably almost adiabatic and compositionally uniform; the more iron-rich inner solid core is a consequence of partial freezing of the outer core, and the energy release from this process sustains the earth's magnetic field; and the thermodynamic properties of the core are well constrained by the application of liquid-state theory to seismic and labroatory data.

  13. The Significance of The Establishment of Intelligent Rehabilitation Medical Records Management System%建立智能化康复医疗档案管理系统的重大意义

    Institute of Scientific and Technical Information of China (English)

    孙立堃

    2015-01-01

    本研究从康复医疗的档案管理工作入手,分析了智能化康复医疗档案管理系统的定义,阐述了建立智能化康复医疗档案管理系统的意义,分析了康复医疗档案管理工作中存在的各类问题,提供了从加强宣传、增加投入、提高素质、制度建设、信息化平台构建等创建智能化康复医疗档案管理系统的措施与方法。%This study from the medical records management work to start,analysis the definition of intelligent rehabilitation medical records management system,expounds the establishment of intelligent rehabilitation medical records management system,analyzes the various problems existing in the archives management of medical rehabilitation,offers from strengthening propaganda,increase investment,improve quality,system the construction of information platformconstruction measures and methods to create intelligent rehabilitation medical records management system.Intelligent; Rehabilitation Archives; Management system; Propaganda; Investment; Quality;Information Platform.

  14. Producing gapped-ferrite transformer cores

    Science.gov (United States)

    Mclyman, W. T.

    1980-01-01

    Improved manufacturing techniques make reproducible gaps and minimize cracking. Molded, unfired transformer cores are cut with thin saw and then fired. Hardened semicircular core sections are bonded together, placed in aluminum core box, and fluidized-coated. After winding is run over box, core is potted. Economical method significantly reduces number of rejects.

  15. Record Club

    CERN Multimedia

    Record Club

    2011-01-01

    http://cern.ch/Record.Club June Selections We have put a significant number of new CDs and DVDs into the Club You will find the full lists at http://cern.ch/record.club and select the «Discs of the Month» button on the left side on the left panel of the web page and then June 2011. New films include the latest Action, Suspense and Science Fiction film hits, general drama movies including the Oscar-winning The King’s Speech, comedies including both chapter of Bridget Jones’s Diary, seven films for children and a musical. Other highlights include the latest Harry Potter release and some movies from the past you may have missed including the first in the Terminator series. New CDs include the latest releases by Michel Sardou, Mylene Farmer, Jennifer Lopez, Zucchero and Britney Spears. There is also a hits collection from NRJ. Don’t forget that the Club is now open every Monday, Wednesday and Friday lunchtimes from 12h30 to 13h00 in Restaurant 2, Building 504. (C...

  16. Palynological records and paleoclimate of core SA09-040 in the south of South China Sea%南海南部SA09-040孔孢粉记录及古气候

    Institute of Scientific and Technical Information of China (English)

    张玉兰; 彭学超; 贾丽; 戴璐

    2012-01-01

    依据南海低纬地区SA09-040孔高分辨率的孢粉记录,自下至上划分了4个孢粉组合带.从孢粉成分的变化,重建了22.25 ka B P以来的植被与气候变化历史.结果表明:孢粉主要来源于婆罗洲和周围岛屿,孢粉1带(22.25~16.6 kaBP),低山雨林植被发育,为暖热气候,从测年时间看,当时为末次冰期晚期.孢粉2带(16.6~10.82 ka B P,为末次冰消期),植被以热带低山雨林和低地雨林为主,针叶的松数量较多,当时的气温比现在低.孢粉3带(全新世早期,10.82~6.43 kaBP),植被以热带低山雨林和低地雨林为主,针叶松属数量减少,气温比前期升高,海平面也上升.孢粉4带(全新世中晚期,6.43 ka B P至今),全新世中期为炎热、湿润的气候环境,全新世晚期可能与婆罗洲现今的植被景观相近,为热、湿的气候环境.%According to the high resolution pollen record in the Core SA09-040 which was taken in the low latitude of the South China Sea, four pollen zones have been divided in ascending order. Based on the pollen composition change,the vegetation evolution and climate change since 22. 25 ka B P were reconstructed. The research result shows that the pollen mainly came from the Borneo and nearby islands. In pollen zone 1(22. 25 ~16. 6 ka B P) , the low mountain rainforest were luxuriant, the climate was warm to hot. Judged from the dating result, the age was the late stage of the Last glacial period. Pollen zone 2(16. 6~10. 82 ka B P, the Last deglaciation) shows that the vegetation were mainly tropical low mountain rainforest and lowland rainforest. There were many conifer pines. The temperature was lower than that of now. Pollen zone 3(the early stage of Holocene, 10. 82~6. 43 ka B P) shows that the vegetation were mainly tropical low mountain rainforest and lowland rainforest. The conifer pines were fewer than that in pollen zone 2, the temperature was higher than before, the sea-level rose. Pollen zone 4(the middle or late

  17. Sedimentary Records of the Paleohurricane Activity in the Bahamas

    Science.gov (United States)

    Wallace, E. J.; Donnelly, J. P.; Wiman, C.; Cashman, M.

    2015-12-01

    Hurricanes pose a threat to human lives and can cause significant destruction of coastal areas. This threat has become more pronounced with recent rises in sea level and coastal populations. Currently, there is a large degree of uncertainty surrounding future changes in tropical cyclone activity. This is due to the limitations of climate models as well as the scarcity and unreliability of the current observational record. With so much uncertainty surrounding the current projections of hurricane activity, it is crucial to establish a longer and more accurate historical record. This study uses sediment cores extracted from blueholes in the Bahamas to develop a record of intense hurricane landfalls in the region dating back more than a millennia. The collected cores were sectioned, split, and scanned on an X-ray fluorescence scanner to obtain a high resolution core profile of the sediments' elemental composition and to identify potential sedimentary structures. Age control of the samples was determined using radiocarbon dating, coarse fraction was measured every centimeter, and hurricane event bed frequency was established for each core. We assess the statistical significance of the patterns observed in the sedimentary record using a coupled ocean-atmosphere hurricane model to simulate storms representative of modern climatology. Cores extracted from two blue holes near South Andros Island provide approximately a 1600 year and a 600 year record respectively, with sedimentation rates exceeding 1 cm/year. Both records contain coarse grained event deposits that correlate with known historical intense hurricane strikes in the Bahamas within age uncertainties. The 1600 year record confirms previous hurricane reconstructions from the Caribbean indicating higher tropical cyclone activity from 500 to 1400 CE. In addition, these new high-resolution records indicate elevated intense hurricane activity in the 17th and 18th centuries CE, when activity is also elevated in lower

  18. Recording-media-related morphology and magnetic properties of crystalline CoPt{sub 3} and CoPt{sub 3}-Au core-shell nanoparticles synthesized via reverse microemulsion

    Energy Technology Data Exchange (ETDEWEB)

    Bahmanrokh, Ghazaleh, E-mail: ghazalehbahmanrokh@yahoo.com; Hashim, Mansor; Matori, Khamirul Amin; Kanagesan, Samikannu; Sabbaghizadeh, Rahim; Ezzad Shafie, Mohd Shamsul [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Navasery, Manizheh; Soltani, Nayereh [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Vaziri, Parisa [Department of Medical Physics and Biomedical Engineering, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2014-09-07

    A comparative experimental study of the magnetic properties of CoPt{sub 3} and CoPt{sub 3}/Au nanoparticles as well as a detailed study of the structural properties of the samples by X-ray diffraction, Transmission electron microscopy, and vibrating sample magnetometer is presented in this work. In addition, the effect of particle size on the structure and magnetic properties of nanoparticles prepared by microemulsion is studied. The correlation between particle size, crystallinity, and magnetization was studied as well. CoPt nanoparticles have been studied intensively over the last decade because of their increased magnetic anisotropy in the ordered phase that can be interesting for high density magnetic recording. A significant high coercivity for as-prepared CoPt{sub 3} and CoPt{sub 3}-Au nanoparticles was obtained at room temperature and enhanced after annealing. The focused aim of our study is to obtain high coercivity at room temperature that follows the Curie-Weiss law. This indicates an interacting system in which the nanoparticles behave like single domain ferromagnetic materials in the particle size range of 8 to 35 nm. In addition, the interaction increases by cooling the samples to low temperature around 15 K. Temperature dependence 1/M graph was obtained to investigate the behavior of nanoparticles at low temperature and shows the best fit with Curie-Weis mode.

  19. Activation of Selected Core Muscles during Pressing

    Directory of Open Access Journals (Sweden)

    Thomas W. Nesser

    2015-10-01

    Full Text Available Introduction: Unstable surface training is often used to activate core musculature during resistance training. Unfortunately, unstable surface training is risky and leads to detraining. Purpose: The purpose of this study was to determine core muscle activation during stable surface ground-based lifts. Methods: Fourteen recreational trained and former NCAA DI athletes (weight 84.2 ± 13.3 kg; height 176.0 ± 9.5 cm; age 20.9 ± 2.0 years volunteered for participation. Subjects completed two ground-based lifts: overhead press and push-press. Surface EMG was recorded from 4 muscles on the right side of the body (Rectus Abdominus (RA, External Oblique (EO, Transverse Abdominus (TA, and Erector Spinae (ES. Results: Paired sample T-tests identified significant muscle activation differences between the overhead press and the push-press included ES and EO. Average and peak EMG for ES was significantly greater in push-press (P<0.01. Anterior displacement of COP was significantly greater in push-press compared to overhead press during the eccentric phase. Conclusion: The push-press was identified as superior in core muscle activation when compared to the overhead pressing exercise. Keywords: torso, stability, weight lifting, resistance training

  20. Millennial-scale phase relationships between ice-core and Mediterranean marine records: insights from high-precision 40Ar/39Ar dating of the Green Tuff of Pantelleria, Sicily Strait

    Science.gov (United States)

    Scaillet, S.; Vita-Scaillet, G.; Rotolo, S. G.

    2013-10-01

    With the advent of annually-resolved polar ice records extending back to 70 ka, marine and continental paleoclimate studies have now matured into a discipline where high-quality age control is essential for putting on an equal pace layer-counted timescale models and Late Quaternary sedimentary records. High-resolution U-Th dating of speleothem records and 40Ar/39Ar dating of globally recorded geomagnetic excursions have recently improved the time calibration of Quaternary archives, reflecting the cross-disciplinary effort made to synchronize the geologic record at the millennial scale. Yet, tie-points with such an absolute age control remain scarce for paleoclimatic time-series extending beyond the radiocarbon timescale, most notably in the marine record. Far-travelled tephra layers recorded both onland and offshore provide an alternative in such instance to synchronize continental and marine archives via high-resolution 40Ar/39Ar dating of the parent volcanic eruption. High-resolution 40Ar/39Ar data are reported herein for one such volcanic marker, the Green Tuff of Pantelleria and its Y-6 tephra equivalent recorded throughout the Central and Eastern Mediterranean. Published radiochronometric and δ18O orbitally-tied ages for this marker horizon scatter widely from about 41 ka up to 56 ka. Our new 40Ar/39Ar age at 45.7 ± 1.0 ka (2σ) reveals that previous estimates are biased by more than their reported errors would suggest, including recent orbital tuning of marine records hosting the tephra bed that are reevaluated in the context of this study. This improved estimate enables potential phase lags and leads to be studied between deep-sea and terrestrial archives with unrivaled (near-millennial) 40Ar/39Ar precision in the marine record.

  1. Packing in protein cores

    Science.gov (United States)

    Gaines, J. C.; Clark, A. H.; Regan, L.; O'Hern, C. S.

    2017-07-01

    Proteins are biological polymers that underlie all cellular functions. The first high-resolution protein structures were determined by x-ray crystallography in the 1960s. Since then, there has been continued interest in understanding and predicting protein structure and stability. It is well-established that a large contribution to protein stability originates from the sequestration from solvent of hydrophobic residues in the protein core. How are such hydrophobic residues arranged in the core; how can one best model the packing of these residues, and are residues loosely packed with multiple allowed side chain conformations or densely packed with a single allowed side chain conformation? Here we show that to properly model the packing of residues in protein cores it is essential that amino acids are represented by appropriately calibrated atom sizes, and that hydrogen atoms are explicitly included. We show that protein cores possess a packing fraction of φ ≈ 0.56 , which is significantly less than the typically quoted value of 0.74 obtained using the extended atom representation. We also compare the results for the packing of amino acids in protein cores to results obtained for jammed packings from discrete element simulations of spheres, elongated particles, and composite particles with bumpy surfaces. We show that amino acids in protein cores pack as densely as disordered jammed packings of particles with similar values for the aspect ratio and bumpiness as found for amino acids. Knowing the structural properties of protein cores is of both fundamental and practical importance. Practically, it enables the assessment of changes in the structure and stability of proteins arising from amino acid mutations (such as those identified as a result of the massive human genome sequencing efforts) and the design of new folded, stable proteins and protein-protein interactions with tunable specificity and affinity.

  2. Climatic Teleconnections Recorded By Tropical Mountain Glaciers

    Science.gov (United States)

    Thompson, L. G.; Permana, D.; Mosley-Thompson, E.; Davis, M. E.

    2014-12-01

    Information from ice cores from the world's highest mountains in the Tropics demonstrates both local climate variability and a high degree of teleconnectivity across the Pacific basin. Here we examine recently recovered ice core records from glaciers near Puncak Jaya in Papua, Indonesia, which lie on the highest peak between the Himalayas and the South American Andes. These glaciers are located on the western side of the Tropical Pacific warm pool, which is the "center of action" for interannual climate variability dominated by El Niño-Southern Oscillation (ENSO). ENSO either directly or indirectly affects most regions of Earth and their populations. In 2010, two ice cores measuring 32.13 m and 31.25 m were recovered to bedrock from the East Northwall Firn ice field. Both have been analyzed in high resolution (~3 cm sample length, 1156 and 1606 samples, respectively) for stable isotopes, dust, major ions and tritium concentrations. To better understand the controls on the oxygen isotopic (δ18 O) signal for this region, daily rainfall samples were collected between January 2013 and February 2014 at five weather stations over a distance of ~90 km ranging from 9 meters above sea level (masl) on the southern coast up to 3945 masl. The calculated isotopic lapse rate for this region is 0.24 ‰/100m. Papua, Indonesian ice core records are compared to ice core records from Dasuopu Glacier in the central Himalayas and from Quelccaya, Huascarán, Hualcán and Coropuna ice fields in the tropical Andes of Peru on the eastern side of the Pacific Ocean. The composite of the annual isotopic time series from these cores is significantly (R2 =0.53) related to tropical Pacific sea surface temperatures (SSTs), reflecting the strong linkage between tropical Pacific SSTs associated with ENSO and tropospheric temperatures in the low latitudes. New data on the already well-documented concomitant loss of ice on Quelccaya, Kilimanjaro in eastern Africa and the ice fields near Puncak

  3. Continuous ice-core chemical analyses using inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    McConnell, Joseph R; Lamorey, Gregg W; Lambert, Steven W; Taylor, Kendrick C

    2002-01-01

    Impurities trapped in ice sheets and glaciers have the potential to provide detailed, high temporal resolution proxy information on paleo-environments, atmospheric circulation, and environmental pollution through the use of chemical, isotopic, and elemental tracers. We present a novel approach to ice-core chemical analyses in which an ice-core melter is coupled directly with both an inductively coupled plasma mass spectrometer and a traditional continuous flow analysis system. We demonstrate this new approach using replicated measurements of ice-core samples from Summit, Greenland. With this method, it is possible to readily obtain continuous, exactly coregistered concentration records for a large number of elements and chemical species at ppb and ppt levels and at unprecedented depth resolution. Such very-high depth resolution, multiparameter measurements will significantly expand the use of ice-core records for environmental proxies.

  4. A Preliminary Paleomagnetic Rsult of Quaternary Drilling Core form Southern Leizhou Peninsula,Guangdong Province

    Institute of Scientific and Technical Information of China (English)

    王俊达; 梁池生; 等

    1999-01-01

    313 orientated samples were collected from Drilling Core ZK1 in southern Leizhou Peninsula for the study of Quaternary paleomagnetic strato-chronology.Te polarity measurement results indicate that the core recorded paleomagnetic information in three main parts:the upper one of the core,from the ground surface to the depth of 39m ,is normally magnetized in polarity,the middle one,from 39m 59 210m in depth,mainly shows reversed polarity and the lower one recorded normal polarity again.They correspond to the Brunhes normal chron,the Matuyama reversed chron and the Guass normal chron in the geomagnetic polarity time scale,respectively.The age of he core could be over 3.4Ma.Meanwhile,the magnetic susceptibility was measured and its result is significant for stratigraphic division and paleoclimatic research.

  5. Significance of ultrasound-guided core needle biopsy in diagnosis of thyroid nodules%超声引导下粗针组织活检在甲状腺结节诊断中的价值

    Institute of Scientific and Technical Information of China (English)

    赵军凤; 钱林学; 张晓丽; 谭小蕖; 刘玉江

    2013-01-01

    目的 探讨超声引导下粗针组织活检(CNB)对甲状腺结节诊断临床上的应用价值.方法 回顾性分析395例超声引导下甲状腺结节CNB的临床资料,对其中278例行外科手术者CNB及术后石蜡病理学结果进行比较.结果 所有患者均穿刺成功.活检取材满意度为100%.1例出现穿刺后局部血肿,经保守治疗后缓解.共穿刺395例患者,其中278例患者行外科手术,术前CNB病理学结果显示:92例考虑为恶性,其中91例为甲状腺乳头状癌,1例为髓样癌;182例考虑为良性,其中其中1例为甲状旁腺腺瘤,48例为甲状腺腺瘤,133例为结节性甲状腺肿及其他非肿瘤性病变.其中273例穿刺病理学结果与术后石蜡病理学结果相符(90例恶性,183例良性),1例为假阳性,4例不确定病例.故超声引导下CNB对甲状腺结节良、恶性鉴别诊断的准确率、敏感性、特异性、漏诊率和误诊率分别为98.20% (273/278)、95.79%(91/95)、99.45%(182/183)、4.21% (4/95)和0.55% (1/183).结论 超声引导下CNB对甲状腺结节具有很高的鉴别诊断价值,是一种安全、有效的方法.%Objective To explore the value of ultrasound-guided core needle biopsy (CNB) in diagnosis of thyroid nodules.Methods The clinical data of 395 patients with thyroid nodules who underwent ultrasound-guided CNB were retrospectively analyzed,and the results of CNB pathology of 278 patients who endured surgery were compared with postoperative wax pathology results.Results All patients completed CNB successfully and satisfaction rate for tissue samples was 100%.Local hematoma occurred in one case and relieved by conservative therapy.The CNB pathology results of 278 cases of patients were as follows:92 cases were malignancy,including 91 cases of papillary thyroid carcinoma,lcase of medullary thyroid carcinoma; 182 cases were benign,including lcase of parathyroid adenoma,48 cases of adenoma,and 133 cases of nodular goitre and other nodular

  6. Camchaya Gagnep., a newly recorded genus of Asteraceae from Guangxi and its Biogeographical significance%凋缨菊属在广西的首次记录及其生物地理学意义

    Institute of Scientific and Technical Information of China (English)

    周广明; 刘演; 侯元同; 高天刚

    2012-01-01

    报道了广西菊科斑鸠菊族的1个新记录属——凋缨菊属,描述了凋缨菊的分类学特征,给出了详细的图解,绘制了整个凋缨菊属的分布图.这一发现表明了我国桂西南热带地区与滇南以及中南半岛在植物区系上的紧密联系.%Camchaya Gagnep. ,a genus of the tribe Vernonieae, Asteraceae,was newly recorded from Guangxi,southern China. We provided a taxonomic description,detailed photographs of the only one representative species C. loloana Kerr, a distribution map of the whole genus. This finding indicated the close floristic affinity between southern Yunnan, Indo-China Peninsula and the tropical areas of southwestern Guangxi.

  7. Significance of the Oviposition Records of Three Western Ghats Endemics, the Malabar Raven, Papilio dravidarum Wood-Mason, Malabar Rose, Atrophaneura pandiyana Moore and Crimson Rose, Atrophaneura hector Linnaeus (Lepidoptera: Papilionidae

    Directory of Open Access Journals (Sweden)

    V.S. Revathy

    2015-01-01

    Full Text Available Observations were made on the biology and bionomics of the three Western Ghats Endemics, the Malabar Raven (Papilio dravidarum Wood-Mason, Malabar Rose (Atrophaneura pandiyana Moore and Crimson Rose (A. hector Linnaeus. The size of the caterpillar (length and breadth, mode of feeding, pupation and emergence were recorded. The biology took 36-40 days for completion in Malabar Raven, 35-37 days in A. pandiyana and A. hector. Butterflies found in different habitats tend to show marked differences in their general appearance and biology as evidenced by the "Ecological races" reported in several species of butterflies. Thorough understanding of the life history and their behavioural patterns of immature stages will help in recognizing geographical and ecological races.

  8. The palynological record of the Eemian interglacial and Early Vistulian glaciation in deposits of the Żabieniec Południowy fossil basin (Łódź Plateau, central Poland, and its palaeogeographic significance

    Directory of Open Access Journals (Sweden)

    Majecka Aleksandra

    2014-12-01

    Full Text Available The vegetation of the Eemian interglacial and Early Vistulian glaciation was reconstructed on the basis of pollen analysis, biogenic and mineral-biogenic sediments from the Żabieniec Południowy locality. It was revealed that the present-day fossil reservoir was formerly a lake existing continuously from the decline of the Warta stadial (LG MPG to the end of the Early Vistulian (EV4. The upper Plenivistulian age of top sediments, previously accepted on the basis of the radiocarbon date 24 200 ± 350 yrs BP (uncalibrated, was not confirmed by pollen analysis. In the pollen record from the nearby Żabieniec mire a break in biogenic accumulation corresponding to the Lower and Middle Plenivistulian was discovered. In view of the character of Plenivistulian morphogenesis in that area it appears that the deposits of both basins illustrate the development of one large melt-out depression during the whole postglacial period.

  9. Effects of Core-Musculature Fatigue on Maximal Shoulder Strength.

    Science.gov (United States)

    Rosemeyer, James R; Hayes, Bradley T; Switzler, Craig L; Hicks-Little, Charlie A

    2015-11-01

    Core stability has been shown to affect lower-extremity motion, but activation of the core has also been observed just before movements of the upper extremity. However, there is limited evidence regarding the effects that core musculature has on upper-extremity strength. To determine the effects of core fatigue on maximal shoulder strength. Crossover study. Sports-medicine research laboratory. 23 participants (15 male and 8 female, age 21.3 ± 2.5 y, height 174.5 ± 10.3 cm, weight 71.3 ± 12.0 kg). All participants performed maximal voluntary isometric contractions in 3 different planes (sagittal, frontal, transverse) of shoulder-joint motion. A core-fatiguing protocol was conducted, and the same 3 shoulder-strength tests were repeated and compared with the initial measurements. Strength measures were recorded in kilograms with a dynamometer. Results showed a significant decrease in strength in the frontal (-0.56 ± 1.06 kg, P = .020) and transverse (-0.89 ± 1.49 kg, P = .012) planes but not in the sagittal plane (-0.20 ± 0.98 kg, P > .05). Furthermore, regardless of the specific strength test measured, results revealed that the 1st (-7.05% ± 11.65%, P = .012) and 2nd (-5.71% ± 12.03%, P = .042) strength-test measurements after the fatiguing protocol were significantly decreased, while the 3rd strength-test measurement (-4.19% ± 12.48%, P = .140) did not show statistical significance. These results indicate that decrease in core stability may have an influence on shoulder strength. The literature suggests that the core is designed for endurance, and this study helps validate its recovery properties. Further research is needed to determine the significance of this effect and how injury rates coincide.

  10. Continuous greenhouse gas measurements from ice cores

    DEFF Research Database (Denmark)

    Stowasser, Christopher

    several applications of the new continuous data sets: (1) Past atmospheric mixing ratios of methane were measured along ca. 800 m of the deep ice core from the North Greenland Eemian Ice Core Drilling project (NEEM) covering almost the complete last glaciation and deglaciation. The record reveals new sub-millennial...

  11. Studies on ice core records of dicarboxylic acids, ω-oxocarboxylic acids, pyruvic acid, α-dicarbonyls and fatty acids from southern Alaska since 1665 AD : A link to climate change in the Northern Hemisphere

    OpenAIRE

    Pokhrel, Ambarish

    2015-01-01

    Alaskan ice core (180 m long, 343 years) has been analyzed for a homologous series of normal (C2 - C11), branched chain (iC4 - iC6), unsaturated (maleic, fumaric, methylmaleic and phthalic), multifunctional dicarboxylic (malic, oxomalonic and 4- oxopimelic), ω-oxocarboxylic acids (ωC2 - ωC9), pyruvic acid, glyoxal and methylglyoxal using gas chromatography (GC/FID) and GC/mass spectrometry (GC/MS) to understand historical changes in water soluble organic aerosols. Similarly,...

  12. When the Earth's Inner Core Shuffles

    Science.gov (United States)

    Tkalcic, H.; Young, M. K.; Bodin, T.; Ngo, S.; Sambridge, M.

    2011-12-01

    Shuffling is a tribal dance recently adapted by teenagers as a street dance. In one of the most popular moves, the so-called "Running Man", a stomp forward on one foot, shifted without being lifted from the ground, is followed by a change of position backwards on the same foot. Here, we present strong observational evidence from a newly observed collection of earthquake doublets that the Earth's inner core "shuffles" exhibiting both prograde and retrograde rotation in the reference frame of the mantle. This discovery is significant on several levels. First, the observed pattern consists of intermittent intervals of quasi-locked and differentially rotating inner core with respect to the Earth's mantle. This means that the angular alignment of the inner core and mantle oscillates in time over the past five decades. Jolting temporal changes are revealed, indicating that during the excursions from the quasi-locked state, the Earth's inner core can rotate both faster and slower than the rest of the planet, thus exhibiting both eastward and westward rotation. According to our results, a short time interval (on the order of one to two years) is needed for the inner core to accelerate to a differential rotation rate of several degrees per year, and typically a slightly longer time is needed to decelerate down to a negligibly small differential rotation rate. These time scales are in agreement with experimental spin-up times obtained when the magnetic torque alone is used to accelerate the inner core. Second, when we integrate the rotation rate over different time intervals, it is possible to explain discrepancies between the body wave and normal modes results for the rate of the inner core differential rotation found by previous authors. We show that the integrated shift in angular alignment and average rotation rates (previously determined to be constant) in normal mode studies are much smaller that those for the body waves. The repeating earthquakes from the South

  13. 丙肝抗体联合丙肝核心抗原检测在丙型肝炎早期诊断中的意义%The significance of hepatitis C antibody combined hepatitis C virus core antigen test in the early diagnosis of hepatitis C

    Institute of Scientific and Technical Information of China (English)

    杜坤; 毛元英

    2015-01-01

    目的:探讨丙肝抗体联合丙肝核心抗原检测在丙型肝炎早期诊断中的意义。方法:选取2013年1月到2014年12月在我院进行体检的人群23771例,所有体检者都进行了丙肝抗体检测,而21928例体检者进行了丙肝核心抗原检测,检测方法都为ELISA法。结果:ELISA法对于丙肝抗体与丙肝核心抗原的检测阳性率分别为0.70%和0.10%。结论:丙肝抗体联合丙肝核心抗原检测在丙型肝炎早期诊断中的应用能有效判定丙型肝炎的传染性,值得推广应用。%Objective To discuss the significance of hepatitis C antibody combined hepatitis C virus core antigen test in the early diagnosis of hepatitis C.Methods We selected 23771 cases of physical examination from January 2013 to December 2014 in our hospital, all subjects were detected for hepatitis C antibody, 21928 subjects were tested for hepatitis C core antigen, detection method is ELISA. Results ELISA method was used to detect the positive rate for hepatitis C antibody and hepatitis C core antigen were 0.70% and 0.10%. Conclusion Hepatitis C antibody combined hepatitis C virus core antigen test can determine effectively hepatitis C infectivity in the early diagnosis of hepatitis C, it is worthy of popularization and application.

  14. Core calculations of JMTR

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Yoshiharu [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment

    1998-03-01

    In material testing reactors like the JMTR (Japan Material Testing Reactor) of 50 MW in Japan Atomic Energy Research Institute, the neutron flux and neutron energy spectra of irradiated samples show complex distributions. It is necessary to assess the neutron flux and neutron energy spectra of an irradiation field by carrying out the nuclear calculation of the core for every operation cycle. In order to advance core calculation, in the JMTR, the application of MCNP to the assessment of core reactivity and neutron flux and spectra has been investigated. In this study, in order to reduce the time for calculation and variance, the comparison of the results of the calculations by the use of K code and fixed source and the use of Weight Window were investigated. As to the calculation method, the modeling of the total JMTR core, the conditions for calculation and the adopted variance reduction technique are explained. The results of calculation are shown. Significant difference was not observed in the results of neutron flux calculations according to the difference of the modeling of fuel region in the calculations by K code and fixed source. The method of assessing the results of neutron flux calculation is described. (K.I.)

  15. Some core contested concepts.

    Science.gov (United States)

    Chomsky, Noam

    2015-02-01

    Core concepts of language are highly contested. In some cases this is legitimate: real empirical and conceptual issues arise. In other cases, it seems that controversies are based on misunderstanding. A number of crucial cases are reviewed, and an approach to language is outlined that appears to have strong conceptual and empirical motivation, and to lead to conclusions about a number of significant issues that differ from some conventional beliefs.

  16. RECORD processing - A robust pathway to component-resolved HR-PGSE NMR diffusometry

    Science.gov (United States)

    Stilbs, Peter

    2010-12-01

    It is demonstrated that very robust spectral component separation can be achieved through global least-squares CORE data analysis of automatically or manually selected spectral regions in complex NMR spectra in a high-resolution situation. This procedure (acronym RECORD) only takes a few seconds and quite significantly improves the effective signal/noise of the experiment as compared to individual frequency channel fitting, like in the generic HR-DOSY approach or when using basic peak height or integral fitting. Results from RECORD processing can be further used as starting value estimates for subsequent CORE analysis of spectral data with higher degree of spectral overlap.

  17. Phenological Records

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Phenology is the scientific study of periodic biological phenomena, such as flowering, breeding, and migration, in relation to climatic conditions. The few records...

  18. Earth's core and the geodynamo

    Science.gov (United States)

    Buffett

    2000-06-16

    Earth's magnetic field is generated by fluid motion in the liquid iron core. Details of how this occurs are now emerging from numerical simulations that achieve a self-sustaining magnetic field. Early results predict a dominant dipole field outside the core, and some models even reproduce magnetic reversals. The simulations also show how different patterns of flow can produce similar external fields. Efforts to distinguish between the various possibilities appeal to observations of the time-dependent behavior of the field. Important constraints will come from geological records of the magnetic field in the past.

  19. Carbonaceous particles in Muztagh Ata ice core, West Kunlun Mountains, China

    Institute of Scientific and Technical Information of China (English)

    LIU XianQin; XU BaiQing; YAO TanDong; WANG NingLian; WU GuangJian

    2008-01-01

    Carbonaceous particles concentrations of OC and EC are determined using a two-step gas chroma-tography system in Muztagh Ata ice core covering the time period of 1955-2000. Over the period rep-resented by the core, OC and EC concentrations appear to have changed significantly, varied in the range of 17.7-216.7 and 6.5-124.6, and averaged 61.8, 32.9 ng·g-1, respectively. The average concen-tration of EC in Muztagh Ata ice core is much lower than that in an Alpine ice core record (100-300 ng·g-1) during the same period, but it is a factor of 14 in Greenland ice core (2.3 ng.g-1), this may induce a strong impact on the snow albedo in the last 46 years in our study area. Observations indicate two periods with obviously high deposition concentrations (1955-1965 and 1974-1989) and two periods with low concentrations (1966-1973 and 1990-1995), as well as a recent increasing trend. By com-paring EC and SO42- concentration variations and deciphering OC/EC ratios recorded in the same ice core, we can judge roughly that the carbonaceous particles deposited in Muztagh Ata ice core were attributed to fossil fuel combustion sources.

  20. Radiometric dating of sediment records in European mountain lakes

    Directory of Open Access Journals (Sweden)

    Peter G. APPLEBY

    2000-09-01

    Full Text Available Sediment cores from seven European mountain lakes collected as part of a study of palaeolimnogical records of climate change (the MOLAR project were dated radiometrically by 210Pb. In spite of the remote locations, only one site recorded more or less uniform sediment accumulation throughout the past 150 years. At three further sites the 210Pb record indicated uniform sedimentation up until ca 1950 but significant increases since then. Stratigraphic dates based on records of fallout 137Cs and 241Am showed that 210Pb supply rates to these core sites had nonetheless remained relatively constant and that the sediments could be dated by the CRS model. At the remaining sites there were indications of episodic changes in both sedimentation rates and 210Pb supply rates. Since the changes were not in proportion, neither of the simple dating models (CRS or CIC was applicable. Using the 137Cs and 241Am stratigraphic dates as reference points it was however possible to construct a realistic chronology for these cores by applying the CRS model piecewise to each time-bounded section.

  1. Dual-core antiresonant hollow core fibers.

    Science.gov (United States)

    Liu, Xuesong; Fan, Zhongwei; Shi, Zhaohui; Ma, Yunfeng; Yu, Jin; Zhang, Jing

    2016-07-25

    In this work, dual-core antiresonant hollow core fibers (AR-HCFs) are numerically demonstrated, based on our knowledge, for the first time. Two fiber structures are proposed. One is a composite of two single-core nested nodeless AR-HCFs, exhibiting low confinement loss and a circular mode profile in each core. The other has a relatively simple structure, with a whole elliptical outer jacket, presenting a uniform and wide transmission band. The modal couplings of the dual-core AR-HCFs rely on a unique mechanism that transfers power through the air. The core separation and the gap between the two cores influence the modal coupling strength. With proper designs, both of the dual-core fibers can have low phase birefringence and short modal coupling lengths of several centimeters.

  2. Core body temperature in obesity.

    Science.gov (United States)

    Heikens, Marc J; Gorbach, Alexander M; Eden, Henry S; Savastano, David M; Chen, Kong Y; Skarulis, Monica C; Yanovski, Jack A

    2011-05-01

    A lower core body temperature set point has been suggested to be a factor that could potentially predispose humans to develop obesity. We tested the hypothesis that obese individuals have lower core temperatures than those in normal-weight individuals. In study 1, nonobese [body mass index (BMI; in kg/m(2)) temperature-sensing capsules, and we measured core temperatures continuously for 24 h. In study 2, normal-weight (BMI of 18-25) and obese subjects swallowed temperature-sensing capsules to measure core temperatures continuously for ≥48 h and kept activity logs. We constructed daily, 24-h core temperature profiles for analysis. Mean (±SE) daily core body temperature did not differ significantly between the 35 nonobese and 46 obese subjects (36.92 ± 0.03°C compared with 36.89 ± 0.03°C; P = 0.44). Core temperature 24-h profiles did not differ significantly between 11 normal-weight and 19 obese subjects (P = 0.274). Women had a mean core body temperature ≈0.23°C greater than that of men (36.99 ± 0.03°C compared with 36.76 ± 0.03°C; P body temperature. It may be necessary to study individuals with function-altering mutations in core temperature-regulating genes to determine whether differences in the core body temperature set point affect the regulation of human body weight. These trials were registered at clinicaltrials.gov as NCT00428987 and NCT00266500.

  3. [Audit: medical record documentation among advanced cancer patients].

    Science.gov (United States)

    Perceau, Elise; Chirac, Anne; Rhondali, Wadih; Ruer, Murielle; Chabloz, Claire; Filbet, Marilène

    2014-02-01

    Medical record documentation of cancer inpatients is a core component of continuity of care. The main goal of the study was an assessment of medical record documentation in a palliative care unit (PCU) using a targeted clinical audit based on deceased inpatients' charts. Stage 1 (2010): a clinical audit of medical record documentation assessed by a list of items (diagnosis, prognosis, treatment, power of attorney directive, advance directives). Stage 2 (2011): corrective measures. Stage 3 (2012): re-assessment with the same items' list after six month. Forty cases were investigated during stage 1 and 3. After the corrective measures, inpatient's medical record documentation was significantly improved, including for diagnosis (P = 0.01), diseases extension and treatment (P documentation for advanced directives (P = 0.145).

  4. Evidence of Historical Supernovae in Ice Cores

    Science.gov (United States)

    Young, Donna

    2011-05-01

    Within the framework of the U.S. Greenland Ice Core Science Project (GISP2), an ice core, known as the GISP H-Core, was collected in June, 1992 adjacent to the GISP2 summit drill site. The project scientists, Gisela A.M. Dreschhoff and Edward J. Zeller, were interested in dating solar proton events with volcanic eruptions. The GISP2-H 122-meter firn and ice core is a record of 415 years of liquid electrical conductivity (LEC) and nitrate concentrations, spanning the years 1992 at the surface through 1577 at the bottom. At the National Ice Core Laboratory in Denver, Colorado, the core (beneath the 12-meter firn) was sliced into 1.5 cm sections and analyzed. The resulting data set consisted of 7,776 individual analyses. The ultrahigh resolution sampling technique resulted in a time resolution of one week near the surface and one month at depth. The liquid electrical conductivity (LEC) sequence contains signals from a number of known volcanic eruptions and provides a dating system at specific locations along the core. The terrestrial and solar background nitrate records show seasonal and annual variations, respectively. However, major nitrate anomalies within the record do not correspond to any known terrestrial or solar events. There is evidence that these nitrate anomalies could be a record of supernovae events. Cosmic X-rays ionize atmospheric nitrogen, producing excess nitrate that is then deposited in the Polar Regions. The GISP2-H ice core has revealed nitrate anomalies at the times of the Tycho and Kepler supernovae. The Cassiopeia A supernova event may be documented in the core as well. We have developed a classroom activity for high school and college students, in which they examine several lines of evidence in the Greenland ice core, discriminating among nearby and mid-latitude volcanic activity, solar proton events, and supernovae. Students infer the date of the Cassiopeia A supernova.

  5. 南极伊利莎白公主地250年来雪芯累积、氧同位素与化学研究%250 years of accumulation, oxygen isotope and chemical records in a firn core from Princess Elizabeth Land, East Antarctica

    Institute of Scientific and Technical Information of China (English)

    张明军; 李忠勤; 任贾文

    2006-01-01

    A 51.85-m firn core collected from site DT001 (accumulation rate 127 kgm-2a-1, mean annual temperature -33.1 °C) on Princess Elizabeth Land, East Antarctica, during the 1996-97 Chinese First Antarctic Inland Expedition has been analyzed for chemical composition and oxygen isotope ratio. A comparison between the seasonal variations of major ions was carried out in order to reduce the dating uncertainty, using the volcanic markers as time constrains. A deposition period of 251 years was determined. The calculated accumulation rates display an increasing trend before 1820, while after 1820, the trend of the accumulation is not obvious. Overall, temperature change in the region shows a slight increasing trend over the past 250 years. But, notably, a temperature decline of -2 oC is observed from 1860 to the present. This feature, at odds with the warming trend over the past century recorded in both hemispheres, likely reflects a regional characteristic related to the lack of a high latitude/low latitude link in the Southern Hemisphere circulation patterns. The results of the glaciochemical records of the firn core show that the mean concentrations of Cl-, Na+ and Mg2+ are similar to those reported from other sites in East Antarctica. However, the mean concentration of Ca2+ is much higher than that reported from other regions, suggesting the influence of the strong local terrestrial sources in Princess Elizabeth Land. There is no evidence of a positive correlation between NO3- concentrations and solar activity (11-year solar cycle and solar cycle length), although solar proton events may account for some of the NO3- peak values in the record.

  6. Atmospheric Methane in Ice Cores

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The reconstruction of air trapped in ice cores provides us the most direct information about atmospheric CH4 variations in the past history. Ice core records from the "Three Poles (Antarctica, Greenland and Tibetan Plateau)" reveal the detailed fluctuations of atmospheric CH4 concentration with time and are allowed to quantify the CH4 differences among latitudes. These data are indispensably in the farther study of the relationship between greenhouse gases and climatic change, and of the past changes in terrestrial CH4 emissions. Ice cores reconstruction indicates that atmospheric CH4 concentration has increased quickly since industrialization, and the present day's level of atmospheric CH4 (1800 ppbv) is unprecedented during the past Glacial-Interglacial climate cycles.

  7. Animal MRI Core

    Data.gov (United States)

    Federal Laboratory Consortium — The Animal Magnetic Resonance Imaging (MRI) Core develops and optimizes MRI methods for cardiovascular imaging of mice and rats. The Core provides imaging expertise,...

  8. Student Records

    Science.gov (United States)

    Fields, Cheryl

    2005-01-01

    Another topic involving privacy has attracted considerable attention in recent months--the "student unit record" issue. The U.S. Department of Education concluded in March that it would be feasible to help address lawmakers' concerns about accountability in higher education by constructing a database capable of tracking students from institution…

  9. Record dynamics

    DEFF Research Database (Denmark)

    Robe, Dominic M.; Boettcher, Stefan; Sibani, Paolo

    2016-01-01

    -facto irreversible and become increasingly harder to achieve. Thus, a progression of record-sized dynamical barriers are traversed in the approach to equilibration. Accordingly, the statistics of the events is closely described by a log-Poisson process. Originally developed for relaxation in spin glasses...

  10. Ice core melt features in relation to Antarctic coastal climate

    NARCIS (Netherlands)

    Kaczmarska, M.; Isaksson, E.; Karlöf, L.; Brandt, O.; Winther, J.G.; van de Wal, R.S.W.; van den Broeke, M.R.; Johnsen, S.J.

    2006-01-01

    Measurement of light intensity transmission was carried out on an ice core S100 from coastal Dronning Maud Land (DML). Ice lenses were observed in digital pictures of the core and recorded as peaks in the light transmittance record. The frequency of ice layer occurrence was compared with climate pro

  11. Coring to the West Antarctic ice sheet bed with a new Deep Ice Sheet Coring (DISC) drill

    Science.gov (United States)

    Bentley, C. R.; Taylor, K. C.; Shturmakov, A. J.; Mason, W. P.; Emmel, G. R.; Lebar, D. A.

    2005-05-01

    As a contribution to IPY 2007-2008, the U.S. ice core research community, supported by the National Science Foundation, plans to core through the West Antarctic ice sheet (WAIS) at the ice-flow divide between the Ross Sea and Amundsen Sea drainage systems. The aim is to develop a unique series of interrelated climatic, ice-dynamic, and biologic records focused on understanding interactions among global earth systems. There will be approximately 15 separate but synergistic projects to analyze the ice and interpret the records. The most significant expected outcome of the WAIS Divide program will be climate records for the last ~40,000 years with an annually resolved chronology (through layer counting), comparable to the records from central Greenland. The data will also extend, at lower temporal resolution, to approximately 100,000 BP. These records will permit comparison of environmental conditions between the northern and southern hemispheres, and study of greenhouse gas concentrations in the paleoatmosphere, with unprecedented detail. To accomplish the coring, an innovative new Deep Ice Sheet Coring (DISC) drill is being built at the University of Wisconsin. The modular design of the bore-hole assembly (sonde) provides high flexibility for producing a 122 mm diameter ice core to depths of 4,000 m with maximum core lengths of 4 m. The DISC drill has a rotating outer barrel that can be used with or without an inner barrel designed to improve core recovery in brittle ice. Separate and independent motors for the drill and pump allow cutter speeds from 0 to 150 rpm and pump rates from 0 to 140 gpm. The high pumping rate should alleviate problems drilling in warm ice near the bed; it also helps make tripping speeds several times faster than with the old US drill. Other innovations include vibration and acoustic sensors for monitoring the drilling process, a segmented core barrel to avoid the formerly persistent problem of bent core barrels, and a high-speed data

  12. THE TROPICAL CONNECTION BETWEEN THE ATLANTIC SECTOR ICE CORES AND THE NORTH PACIFIC MT LOGAN ICE CORE

    Science.gov (United States)

    Fisher, D. A.

    2009-12-01

    The stable isotope record from the Mt Logan, Yukon, Canada ice core spans the late Glacial to present and shows very large and sudden variations in O18 during the Holocene . It is hypothesized that they are driven by changes in the water sources ,which in turn, are determined by the state of ENSO. There seems to be no correlations between the Logan ice core isotope record and those from the North Atlantic (Greenland and Eastern Canadian Arctic). Using the stacked and co-dated Greenland and Eastern Canadian Arctic ice core records from the Holocene, it is possible to reproduce the Logan isotope record by subtracting the stacked Atlantic record from itself with an 1100 year lag. The correlations obtainable are -0.43 for 50 year average series. This correlation is significant at the 99.8 % level . The 1100 lag has also been found in previous studies comparing the Greenland to Antarctic ice cores (Stocker and Johnsen,2003). It is argued that such a lagged difference series is a proxy for the difference between the ocean water surface and deep temperatures in the tropical Pacific . ENSO’s amplitude is driven by this temperature difference, (Sun 2000). When the deep water is too warm, then the difference is too small to produce ENSO oscillations and strong tropical easterly winds persist (ie strong and constant La Nina). The ice core records from Mt Logan , Greenland and Eastern Arctic Canada all point to a similar history of ENSO oscillation strength. Prior to ~ 4200 BP the strong and constant La Nina tended to drive the tropical Pacific winds and moisture across to produce strong and reliable monsoons. Since 4200 BP the “modern” and variable pattern has been in place. There was a smaller scale shift about 1840 AD . For about a couple of centuries prior to 1840 AD , La Nina was in charge and after there were the oscillations that are thought of as normal. If the 1100 year lag between surface and bottom temperatures is true and if the bottom temperatures are echoes

  13. ATLAS Recordings

    CERN Multimedia

    Steven Goldfarb; Mitch McLachlan; Homer A. Neal

    Web Archives of ATLAS Plenary Sessions, Workshops, Meetings, and Tutorials from 2005 until this past month are available via the University of Michigan portal here. Most recent additions include the Trigger-Aware Analysis Tutorial by Monika Wielers on March 23 and the ROOT Workshop held at CERN on March 26-27.Viewing requires a standard web browser with RealPlayer plug-in (included in most browsers automatically) and works on any major platform. Lectures can be viewed directly over the web or downloaded locally.In addition, you will find access to a variety of general tutorials and events via the portal.Feedback WelcomeOur group is making arrangements now to record plenary sessions, tutorials, and other important ATLAS events for 2007. Your suggestions for potential recording, as well as your feedback on existing archives is always welcome. Please contact us at wlap@umich.edu. Thank you.Enjoy the Lectures!

  14. Trial-Based Thought Record (TBTR: preliminary data on a strategy to deal with core beliefs by combining sentence reversion and the use of analogy with a judicial process Registro de Pensamentos com Base no Processo (RPBP: dados preliminares de uma estratégia para lidar com crenças nucleares, combinando reversão de sentenças e analogia com o processo jurídico

    Directory of Open Access Journals (Sweden)

    Irismar Reis de Oliveira

    2008-03-01

    Full Text Available OBJECTIVE: To propose the Trial-Based Thought Record, a modified, 7-column thought record addressing core beliefs by sentence reversion and the analogy to a trial. METHOD: Clients (n = 30 participated in a simulation of a trial and exhibited shifts in their adherence to core beliefs and in the intensity of corresponding emotions after each step (investigation, prosecutor’ s plea, defense attorney’ s plea, prosecutor’ s second plea, defense attorney’ s second plea, and jury verdict during a session. RESULTS: Significant mean reductions existed between percent values after investigation (taken as baseline and defense attorney’ s plea (p OBJETIVO: Propor o Registro de Pensamentos com Base no Processo, versão modificada, com sete colunas, para lidar com as crenças nucleares por meio da combinação da reversão de sentenças e a analogia com um processo jurídico. MÉTODO: Os clientes (n = 30 participaram da simulação de um júri e exibiram mudanças na adesão às crenças nucleares e na intensidade das emoções correspondentes após cada passo durante uma sessão (investigação, alegação do promotor, alegação do advogado de defesa, réplica do promotor, tréplica do advogado de defesa e veredicto do júri. RESULTADOS: Reduções médias significantes foram observadas entre os valores percentuais após a investigação (tomada como valor basal, a alegação da defesa (p < 0,001 e o veredicto do júri, tanto das crenças (p < 0,001 quanto da intensidade das emoções (p < 0,001. Diferenças significantes foram também observadas entre as primeira e segunda alegações da defesa (p = 0,009 e entre a segunda alegação da defesa e o veredicto do júri no que diz respeito às crenças nucleares (p = 0,005 e às emoções (p = 0,02. CONCLUSÃO: O Registro de Pensamentos com Base no Processo pode, pelo menos temporariamente, ajudar os pacientes, de forma construtiva, a reduzirem a adesão às crenças nucleares negativas e emo

  15. The significance of minerals in livestock nutrition was recorded in ...

    African Journals Online (AJOL)

    in sheep nutrition but no response to calcium supplemett- ... Experiments with potassium iodide as a supplement were not .... These regional trends should be treated with caution ... adjustments, when accurately formulated, can, at nominal.

  16. Climatic and Environmental Records within a Shallow Ice Core at Laohugou Glacier No.12,Qilian Mountains%祁连山老虎沟12号冰川浅冰芯记录的气候环境信息

    Institute of Scientific and Technical Information of China (English)

    崔晓庆; 王瑜; 任贾文; 秦翔; 杜文涛; 孙维君; 余光明; 王泽斌; 王晓香; 孙维贞

    2011-01-01

    2006年6月在祁连山西段大雪山的老虎沟12号冰川钻取了一支20.12m的浅冰芯,对冰芯中化学组成成分的浓度变化特征和来源分析进行了研究.结果表明,冰芯中δ18 O和可溶性离子含量变化均显示了明显的周期性变化,δ18 O与祁连山西段温度有很好的正相关关系.通过相关分析和HYS-PLIT后向轨迹分析表明,老虎沟12号冰川冰芯中可溶性离子主要来源于我国西北干旱、半干旱区的陆源矿物粉尘和冰川区周边的盐湖矿物风化物.%In June 2006,a shallow ice core,20.12 m in length,was recovered from an elevation of 5 040 m in the northern branch firn basin of the Laohugou Glacier No.12 in the western part of the Qilian Mountains.Concentrations of oxygen isotope(δ18O) and major soluble ions were determined.It is found that the relationship between the value of δ18O and air temperature in the west Qilian Mountains is positively correlated.Correlation analysis and backward trajectory model analysis show that the main soluble ions originate mainly from the arid and semi-arid sand-dust areas in Northwest China.However,besides the input of terrigenous material,part of Na+,Cl-and SO2——4 also originates from salt particles weathering from the numerous salt lakes around the plateau glacier areas.

  17. Driver of the interannual variations of isotope in ice core from the middle of Tibetan Plateau

    Science.gov (United States)

    Shao, Lili; Tian, Lide; Cai, Zhongyin; Cui, Jiangpeng; Zhu, Dayun; Chen, Yanhui; Palcsu, László

    2017-05-01

    Understanding the climatic significance of stable isotope in precipitation and ice cores on the Tibetan Plateau (TP) is of critical for the paleoclimate rebuilding. However, there is a gap between the seasonal control of precipitation and long-term isotope record from ice core. Here we present a well-dated ice core isotope record from the middle of the TP (mid-TP). Isotope variations in the past decades from this ice core show strong anti-phase relation with Southern Oscillation Index, confirming unequivocally that the large scale atmospheric circulation through the El Nino Southern Oscillation cycle, rather local climate parameters, controls the interannual signal in ice cores from the mid-TP. Results also show that the cloud top height in the northern Indian Ocean is in association with the interannual variations, confirming the same mechanism controlling the precipitation δ18O in southwest Asia and southeast Asia. The study will improve the understanding of the interannual change of Tibetan Plateau ice core isotope signal, and also the hydrological cycle in the southwest Asian region.

  18. Preliminaries on core image analysis using fault drilling samples; Core image kaiseki kotohajime (danso kussaku core kaisekirei)

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, T.; Ito, H. [Geological Survey of Japan, Tsukuba (Japan)

    1996-05-01

    This paper introduces examples of image data analysis on fault drilling samples. The paper describes the following matters: core samples used in the analysis are those obtained from wells drilled piercing the Nojima fault which has moved in the Hygoken-Nanbu Earthquake; the CORESCAN system made by DMT Corporation, Germany, used in acquiring the image data consists of a CCD camera, a light source and core rotation mechanism, and a personal computer, its resolution being about 5 pixels/mm in both axial and circumferential directions, and 24-bit full color; with respect to the opening fractures in core samples collected by using a constant azimuth coring, it was possible to derive values of the opening width, inclination angle, and travel from the image data by using a commercially available software for the personal computer; and comparison of this core image with the BHTV record and the hydrophone VSP record (travel and inclination obtained from the BHTV record agree well with those obtained from the core image). 4 refs., 4 figs.

  19. Characterizing Facesheet/Core Disbonding in Honeycomb Core Sandwich Structure

    Science.gov (United States)

    Rinker, Martin; Ratcliffe, James G.; Adams, Daniel O.; Krueger, Ronald

    2013-01-01

    Results are presented from an experimental investigation into facesheet core disbonding in carbon fiber reinforced plastic/Nomex honeycomb sandwich structures using a Single Cantilever Beam test. Specimens with three, six and twelve-ply facesheets were tested. Specimens with different honeycomb cores consisting of four different cell sizes were also tested, in addition to specimens with three different widths. Three different data reduction methods were employed for computing apparent fracture toughness values from the test data, namely an area method, a compliance calibration technique and a modified beam theory method. The compliance calibration and modified beam theory approaches yielded comparable apparent fracture toughness values, which were generally lower than those computed using the area method. Disbonding in the three-ply facesheet specimens took place at the facesheet/core interface and yielded the lowest apparent fracture toughness values. Disbonding in the six and twelve-ply facesheet specimens took place within the core, near to the facesheet/core interface. Specimen width was not found to have a significant effect on apparent fracture toughness. The amount of scatter in the apparent fracture toughness data was found to increase with honeycomb core cell size.

  20. Record club

    CERN Multimedia

    Record club

    2010-01-01

      Bonjour a tous, Voici les 24 nouveaux DVD de Juillet disponibles depuis quelques jours, sans oublier les 5 CD Pop musique. Découvrez la saga du terroriste Carlos, la vie de Gainsbourg et les aventures de Lucky Luke; angoissez avec Paranormal Activity et évadez vous sur Pandora dans la peau d’Avatar. Toutes les nouveautés sont à découvrir directement au club. Pour en connaître la liste complète ainsi que le reste de la collection du Record Club, nous vous invitons sur notre site web: http://cern.ch/crc. Toutes les dernières nouveautés sont dans la rubrique « Discs of the Month ». Rappel : le club est ouvert les Lundis, Mercredis, Vendredis de 12h30 à 13h00 au restaurant n°2, bâtiment 504. A bientôt chers Record Clubbers.  

  1. Record Club

    CERN Multimedia

    Record Club

    2011-01-01

    http://cern.ch/Record.Club November  Selections Just in time for the holiday season, we have added a number of new CDs and DVDs into the Club. You will find the full lists at http://cern.ch/record.club; select the "Discs of the Month" button on the left side on the left panel of the web page and then Nov 2011. New films include the all 5 episodes of Fast and Furious, many of the most famous films starring Jean-Paul Belmondo and those of Louis de Funes and some more recent films such as The Lincoln Lawyer and, according to some critics, Woody Allen’s best film for years – Midnight in Paris. For the younger generation there is Cars 2 and Kung Fu Panda 2. New CDs include the latest releases by Adele, Coldplay and the Red Hot Chili Peppers. We have also added the new Duets II CD featuring Tony Bennett singing with some of today’s pop stars including Lady Gaga, Amy Winehouse and Willy Nelson. The Club is now open every Monday, Wednesday and Friday ...

  2. ATLAS Recordings

    CERN Multimedia

    Jeremy Herr; Homer A. Neal; Mitch McLachlan

    The University of Michigan Web Archives for the 2006 ATLAS Week Plenary Sessions, as well as the first of 2007, are now online. In addition, there are a wide variety of Software and Physics Tutorial sessions, recorded over the past couple years, to chose from. All ATLAS-specific archives are accessible here.Viewing requires a standard web browser with RealPlayer plug-in (included in most browsers automatically) and works on any major platform. Lectures can be viewed directly over the web or downloaded locally.In addition, you will find access to a variety of general tutorials and events via the portal. Shaping Collaboration 2006The Michigan group is happy to announce a complete set of recordings from the Shaping Collaboration conference held last December at the CICG in Geneva.The event hosted a mix of Collaborative Tool experts and LHC Users, and featured presentations by the CERN Deputy Director General, Prof. Jos Engelen, the President of Internet2, and chief developers from VRVS/EVO, WLAP, and other tools...

  3. Record Club

    CERN Multimedia

    Record Club

    2011-01-01

    http://cern.ch/Record.Club Nouveautés été 2011 Le club de location de CDs et de DVDs vient d’ajouter un grand nombre de disques pour l’été 2011. Parmi eux, Le Discours d’un Roi, oscar 2011 du meilleur film et Harry Potter les reliques de la mort (1re partie). Ce n’est pas moins de 48 DVDs et 10 CDs nouveaux qui vous sont proposés à la location. Il y en a pour tous les genres. Alors n’hésitez pas à consulter notre site http://cern.ch/record.club, voir Disc Catalogue, Discs of the month pour avoir la liste complète. Le club est ouvert tous les Lundi, Mercredi, Vendredi de 12h30 à 13h dans le bâtiment du restaurent N°2 (Cf. URL: http://www.cern.ch/map/building?bno=504) A très bientôt.  

  4. Temporal trends in West Antarctic surface mass balance: do large scale modes of climate contribute to observed records?

    Science.gov (United States)

    Carpenter, M.; Rupper, S.; Williams, J.; Burgener, L. K.; Koenig, L.; Forster, R. R.; Koutnik, M. R.; Skinner, R.; Miege, C.; Brucker, L.

    2013-12-01

    Western Antarctica has been warming significantly at a rate of 0.17× 0.06 degrees C per decade from 1957 to 2006, with the strongest warming in the winter and spring months. Annual accumulation rates in the central WAIS have been decreasing over the same time period, in spite of rising temperatures. This is somewhat unexpected, as saturation vapor pressure increases with increasing temperature. One possible explanation of this observation could be related to synoptic-scale modes of climate, principally the Southern Annular Mode (SAM) and the El Nino Southern Oscillation (ENSO). These modes of climate are known to modify the track and strength of storms seasonally, but the true extent of the influence of these modes on accumulation in central WAIS is not well known. This is due, in part, to sparse instrumental weather data which makes it difficult to understand the spatial and temporal variability of the central WAIS Surface Mass Balance (SMB). Firn cores provide an excellent temporal SMB record that can fill this data gap, but are spatially limited. The spatial limitation of individual cores can be remedied by creating a network of firn cores over a region, which overcomes small scale variability and provides a regional representation of SMB over the temporal length of the firn core records. The 2011 Satellite Era Accumulation Traverse (SEAT) adds nine new firn cores (20 m deep, spanning 2010-1981) to existing cores within the same region of the central WAIS to improve the spatial network of regional SMB measurements. SMB is reconstructed from the firn cores, and are compared to simulated accumulation from five climate models and reanalyses datasets. The combination of firn cores and simulated records are used to investigate wether SAM and ENSO significantly influence SMB in the central WAIS. The new suite of cores show a statistically significant negative trend in accumulation during the past three decades, which is consistent with results from the previous cores

  5. The long-term records of carbon burial fluxes in sediment cores of culture zones from Sanggou Bay%桑沟湾养殖海域沉积物中碳埋藏通量的长期记录

    Institute of Scientific and Technical Information of China (English)

    刘赛; 杨茜; 杨庶; 孙耀; 杨桂朋

    2014-01-01

    Total carbon (TC),total organic carbon (TOC),total inorganic carbon (TIC)and marine-derived organic carbon (Ca )in two sediment cores of the Sanggou Bay were analyzed.Combined with sedimentary chronose-quence,the burial fluxes (BF)of carbon were determined.The result shows that burial fluxes of carbon were rela-tively steady before 1900s;however,along with the rise of the industrial revolution,natural small shellfish thrived due to the increase of nutrients in the inner bay,leading to a rapid increase of burial fluxes;and then,from 1960s, with the development of large-scale artificial farming,carbon burial fluxes gradually reached a steady state again be-cause of the growing effort of harvesting.Before the 1960s,the ratios of BFC/BFTOC and BFC a/BFTC were under a 20% and 4% respectively,after that time,with the expansion of farming activities,although the ratios keep increas-ing,the ratio of BFTOC/BFTC were under 40% all the time.The ratio of BFTIC/BFTC in Sanggou Bay,which were between 60% and 98%,was higher than the ratio (about 15%)in the central Huanghai Sea.The high ratio of TIC/TC in Sanggou Bay may result in great errors when using TOC or Ca to estimate the burial fluxes of carbon.%对取自桑沟湾北部和南部养殖海域2个站位柱状沉积物样品进行研究,测定了它们的总碳(TC)、有机碳(TOC)、无机碳(TIC)含量,估算了海源有机碳(Ca ),结合沉积物年代序列测定,对碳的来源和埋藏通量(BF)进行分析。结果表明:从19世纪到20世纪初,桑沟湾碳埋藏基本处于平稳期;20世纪初开始,伴随着中国工业革命兴起,湾内营养水平提高,大量天然小型贝类繁殖及残骸埋藏使桑沟湾碳埋藏量有大幅度突跃;20世纪60年代以来人工养殖活动兴起及到90年代大规模养殖后,天然贝类繁殖受抑制且伴随养殖产品的不断收获,使此期间碳埋藏量又处于平稳期。20世纪60年代前BFCa/BFTOC和 BFCa

  6. k-core covers and the core

    NARCIS (Netherlands)

    Sanchez-Rodriguez, E.; Borm, Peter; Estevez-Fernandez, A.; Fiestras-Janeiro, G.; Mosquera, M.A.

    2015-01-01

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  7. Academic Rigor: The Core of the Core

    Science.gov (United States)

    Brunner, Judy

    2013-01-01

    Some educators see the Common Core State Standards as reason for stress, most recognize the positive possibilities associated with them and are willing to make the professional commitment to implementing them so that academic rigor for all students will increase. But business leaders, parents, and the authors of the Common Core are not the only…

  8. k-core covers and the core

    NARCIS (Netherlands)

    Sanchez-Rodriguez, E.; Borm, Peter; Estevez-Fernandez, A.; Fiestras-Janeiro, G.; Mosquera, M.A.

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  9. High-resolution carbon dioxide concentration record 650,000-800,000 years before present

    DEFF Research Database (Denmark)

    Lüthi, Dieter; Le Floch, Martine; Bereiter, Bernhard

    2008-01-01

    Changes in past atmospheric carbon dioxide concentrations can be determined by measuring the composition of air trapped in ice cores from Antarctica. So far, the Antarctic Vostok and EPICA Dome C ice cores have provided a composite record of atmospheric carbon dioxide levels over the past 650......,000 years. Here we present results of the lowest 200 m of the Dome C ice core, extending the record of atmospheric carbon dioxide concentration by two complete glacial cycles to 800,000 yr before present. From previously published data and the present work, we find that atmospheric carbon dioxide...... is strongly correlated with Antarctic temperature throughout eight glacial cycles but with significantly lower concentrations between 650,000 and 750,000 yr before present. Carbon dioxide levels are below 180 parts per million by volume (p.p.m.v.) for a period of 3,000 yr during Marine Isotope Stage 16...

  10. FAST FOSSIL ROTATION OF NEUTRON STAR CORES

    Energy Technology Data Exchange (ETDEWEB)

    Melatos, A., E-mail: amelatos@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia)

    2012-12-10

    It is argued that the superfluid core of a neutron star super-rotates relative to the crust, because stratification prevents the core from responding to the electromagnetic braking torque, until the relevant dissipative (viscous or Eddington-Sweet) timescale, which can exceed {approx}10{sup 3} yr and is much longer than the Ekman timescale, has elapsed. Hence, in some young pulsars, the rotation of the core today is a fossil record of its rotation at birth, provided that magnetic crust-core coupling is inhibited, e.g., by buoyancy, field-line topology, or the presence of uncondensed neutral components in the superfluid. Persistent core super-rotation alters our picture of neutron stars in several ways, allowing for magnetic field generation by ongoing dynamo action and enhanced gravitational wave emission from hydrodynamic instabilities.

  11. RECORD CLUB

    CERN Multimedia

    Record Club

    2010-01-01

    DVD James Bond – Series Complete To all Record Club Members, to start the new year, we have taken advantage of a special offer to add copies of all the James Bond movies to date, from the very first - Dr. No - to the latest - Quantum of Solace. No matter which of the successive 007s you prefer (Sean Connery, George Lazenby, Roger Moore, Timothy Dalton, Pierce Brosnan or Daniel Craig), they are all there. Or perhaps you have a favourite Bond Girl, or even perhaps a favourite villain. Take your pick. You can find the full selection listed on the club web site http://cern.ch/crc; use the panel on the left of the page “Discs of the Month” and select Jan 2010. We remind you that we are open on Mondays, Wednesdays and Fridays from 12:30 to 13:00 in Restaurant 2 (Bldg 504).

  12. Record breakers

    CERN Document Server

    Antonella Del Rosso

    2012-01-01

    In the sixties, CERN’s Fellows were but a handful of about 50 young experimentalists present on site to complete their training. Today, their number has increased to a record-breaking 500. They come from many different fields and are spread across CERN’s different activity areas.   “Diversifying the Fellowship programme has been the key theme in recent years,” comments James Purvis, Head of the Recruitment, Programmes and Monitoring group in the HR Department. “In particular, the 2005 five-yearly review introduced the notion of ‘senior’ and ‘junior’ Fellowships, broadening the target audience to include those with Bachelor-level qualifications.” Diversification made CERN’s Fellowship programme attractive to a wider audience but the number of Fellows on site could not have increased so much without the support of EU-funded projects, which were instrumental in the growth of the programme. ...

  13. High resolution optically stimulated luminescence dating of a sediment core from the southwestern Sea of Okhotsk

    DEFF Research Database (Denmark)

    Sugisaki, S.; Buylaert, J. P.; Murray, A. S.;

    2012-01-01

    in application to a 19 m marine sediment core (MR0604-PC04A) taken from the southwestern Sea of Okhotsk, immediately to the north of Hokkaido, Japan. Fine-grained quartz (4 to 11 mu m) was chosen as the dosimeter, and a single-aliquot regenerative-dose protocol was used for the determination of equivalent dose...... (D-e), with stimulation by both infrared and blue light. The suitability of the measurement procedure was confirmed using dose recovery tests. A high resolution record (similar to 2 OSL ages/m) identified clear sedimentation rate changes down the core. The OSL ages are significantly dependent...

  14. Selectivity of peptide bond dissociation on excitation of a core electron: Effects of a phenyl group

    Science.gov (United States)

    Tsai, Cheng-Cheng; Chen, Jien-Lian; Hu, Wei-Ping; Lin, Yi-Shiue; Lin, Huei-Ru; Lee, Tsai-Yun; Lee, Yuan T.; Ni, Chi-Kung; Liu, Chen-Lin

    2016-09-01

    The selective dissociation of a peptide bond upon excitation of a core electron in acetanilide and N-benzylacetamide was investigated. The total-ion-yield near-edge X-ray absorption fine structure spectra were recorded and compared with the predictions from time-dependent density functional theory. The branching ratios for the dissociation of a peptide bond are observed as 16-34% which is quite significant. This study explores the core-excitation, the X-ray photodissociation pathways, and the theoretical explanation of the NEXAFS spectra of organic molecules containing both a peptide bond and a phenyl group.

  15. Core Forensics: Earth's Accretion and Differentiation

    Science.gov (United States)

    Badro, J.; Brodholt, J. P.; Siebert, J.; Piet, H.; Ryerson, F. J.

    2013-12-01

    Earth's accretion and its primitive differentiation are intimately interlinked processes. One way to constrain accretionary processes is by looking at the major differentiation event that took place during accretion: core formation. Understanding core formation and core composition can certainly shed a new light on early and late accretionary processes. On the other hand, testing certain accretionary models and hypothesis (fluxes, chemistries, timing) allows -short of validating them- at the very least to unambiguously refute them, through the 'filter'' of core formation and composition. Earth's core formed during accretion as a result of melting, phase-separation, and segregation of accretionary building blocks (from meteorites to planetesimals). The bulk composition of the core and mantle depends on the evolution (pressure, temperature, composition) of core extraction during accretion. The entire process left a compositional imprint on both reservoirs: (1) in the silicate Earth, in terms of siderophile trace-element (Ni, Co, V, Cr, among others) concentrations and isotopic fractionation (Si, Cu, among others), a record that is observed in present-day mantle rocks; and (2) on the core, in terms of major element composition and light elements dissolved in the metal, a record that is observed by seismology through the core density-deficit. This imprint constitutes actually a fairly impressive set of evidence (siderophile element concentration and fractionation, volatile and siderophile element isotopic fractionation), can be used today to trace back the primordial processes that occurred 4.5 billion years ago. We are seeking to provide an overhaul of the standard core formation/composition models, by using a new rationale that bridges geophysics and geochemistry. The new ingredients are (1) new laser-heated diamond anvil cell partitioning data, dramatically extending the previous P-T conditions for experimental work, (2) ab initio molecular dynamics calculations to

  16. Medical Secretaries’ Care of Records

    DEFF Research Database (Denmark)

    Bossen, Claus; Jensen, Lotte Groth; Witt, Flemming

    2012-01-01

    We describe the cooperative work of medical secretaries at two hospital departments, during the implementation of an electronic health record system. Medical secretaries' core task is to take care of patient records by ensuring that also do information gatekeeping and articulation work. The EHR...... to health informatics and CSCW, this case study identifies their importance, and suggests that they and other non-clinical groups should be considered, when developing health care IT. We propose the term 'boundary-object trimming', to conceptualize their contributions to hospitals' cooperative work...

  17. Medical Secretaries’ Care of Records

    DEFF Research Database (Denmark)

    Bossen, Claus; Jensen, Lotte Groth; Witt, Flemming

    2012-01-01

    We describe the cooperative work of medical secretaries at two hospital departments, during the implementation of an electronic health record system. Medical secretaries' core task is to take care of patient records by ensuring that also do information gatekeeping and articulation work. The EHR...... implementation stressed their importance to the departments' work arrangements, coupled their work more tightly to that of other staff, and led to task drift among professions. information is complete, up to date, and correctly coded. Medical secretaries While medical secretaries have been relatively invisible...

  18. Timing And Processes Of Earth's Core Differentiation.

    Science.gov (United States)

    Allegre, C. J.; Manhes, G.; Gopel, C.

    2004-12-01

    iron-sulphur compounds of 5 vol% solid olivine, through channel on triple junction between minerals. This study allows us to reconsider the precedent proposition (Stevenson, 1990) based on experimental and theoretical considerations suggesting that percolation of metallic iron rich liquid through a mostly solid silicate matrix is largely prevented because of the high surface tension of iron. During formation and segregation of the Fe-FeS eutectic, W isotopic equilibration is limited by the diffusion through the solid silicate matrix. During the further Earth's growth, impact melting increased and has induced a progressive melting of BSE up to the formation of magma ocean at the end of the planet's accretion. Before the occurrence of the magma ocean, W equilibration between impactors and BSE has not been complete This incomplete isotopic exchange between terrestrial metal and metal originating from impactors with solid part of BSE during early accretion of the Earth leads to the observed excess of 182W of present BSE. It occurs when the 182W production in BSE is most significant, due to the short half-life of 182Hf. The change of segregation mechanisms of Earth's core during planet's growth and short-sightedness of Hf-W chronometer focused to the early segregation of Earth's core make the divergence with the U-Pb and I-Xe terrestrial records. Yin et al. 2002, Nature 418, 949-952. Kleine et al. 2002, Nature 418, 952-955. Schoenberg et al. 2002, Geochim. Cosmochim. Acta 66, 3151-3160. Wetherill 1986, in Origin of the Moon, eds Hartmann et al., LPI, 519-550. Yoshino et al. 2003, Nature 422, 154-157. Stevenson 1990, in Origin of the Earth, eds Newson et al., LPI, 231-249.

  19. 3Ma以来黄土高原朝那黄土-红粘土序列赤铁矿记录及其古气候意义%HEMATITE RECORD OF 3Ma LOESS-RED CLAY SEQUENCES IN THE CENTRAL CHINESE LOESS PLATEAU 3Ma AND ITS PALEOCLIMATIC SIGNIFICANCE

    Institute of Scientific and Technical Information of China (English)

    李香钰; 方小敏; 杨一博; 昝金波

    2012-01-01

    Many significant warm and cool climate events occurred during the Cenozoic, and one of the most intriguing climate events of the Neogene was the Middle Miocene Climate Optimum ( MMCO) , which occurred at about 15 Ma and represents a geologically recent warming event unrelated to human activity that may mirror future climate change in terms of the average global surface temperature increase. Zhuanglang( ZL) County ( 35°13'N, 106°05'E) ,on the western CLP,is 50km northeast of Qin'an section and is widely covered with red clay sediments, in order to get a continuous high-resolution record,the ZL drilling core was obtained. From the study of the magnetostratigraphic we can know that the Late Cenozoic eolian red clay sequences of ZL covering an age range from 25. 6Ma to 4. 8Ma also include the warm climate change period of the Middle Miocene Climate Optimum, which is rich archive of paleoclimatic changes. We choose red clay experimental samples of susceptibility with a spacing of 20cm, then according to the susceptibility variations choose typical samples to do other rock magnetic experiment. The MMCO representative samples were collected from 300 - 420m, covering an age range of 17.5 ~ 13. 5Ma. To make a comparison of the characteristic of rock magnetism about the MMCO representative samples, we also collected representative samples from the Preceding-MMCO ( samples collected from 420 ~ 450m, covering an age range of 18. 0 ~ 17. 5Ma) and Post-MMCO( samples collected from 250 ~ 300m, covering an age range of 13. 5 -12. Oma) . In this study, a multi-parameter rock magnetic investigation such as the magnetic susceptibility ( x) temperature-dependent magnetic susceptibility curve(x-T curves) ,x-T curves of the representative samples heated to different temperatures, IRM acquisition and reverse field demagnetization of IRM2.7T ( IRM acquires at an applied field of 2. 7T)and magnetic hysteresis loops were carried on samples collected from the Zhuanglang red clay drilling

  20. Continuous Chemistry in Ice Cores

    DEFF Research Database (Denmark)

    Kjær, Helle Astrid

    originating from volcanic eruptions, crucial for cross-dating ice cores and relevant for climate interpretations. The method includes a heat bath to minimize the acidifying effect of CO2 both from the laboratory and from the ice itself. While for acidic ice the method finds similar concentrations of H......Ice cores provide high resolution records of past climate and environment. In recent years the use of continuous flow analysis (CFA) systems has increased the measurement throughput, while simultaneously decreasing the risk of contaminating the ice samples. CFA measurements of high temporal...... resolution increase our knowledge on fast climate variations and cover a wide range of proxies informing on a variety of components such as atmospheric transport, volcanic eruptions, forest fires and many more. New CFA methods for the determination of dissolved reactive phosphorus (DRP) and pH are presented...

  1. Core history from paleomagnetic data: Potential changes in stratification but no evidence for a Mesoproterozoic inner core age

    Science.gov (United States)

    Smirnov, Aleksey; Tarduno, John; Kulakov, Evgeniy; McEnroe, Suzanne; Bono, Richard

    2016-04-01

    Data on the long-term evolution of Earth's magnetic field intensity are crucial for understanding the mechanisms of the geodynamo and planetary evolution. However, the paleointensity record in rocks may be adversely affected by a plethora of physical processes which must be taken into account when analyzing the paleointensity database. Recently, a statistical analysis of the Precambrian paleointensity database was used to claim that the solid inner core formed in the Mesoproterozoic, and that this onset time constrains the thermal conductivity in the core to "moderate" values. Here, we demonstrate that the data selection criteria used in this analysis failed to filter out data that significantly overestimate the true paleofield strength due to the presence of non-ideal carriers of paleointensity signals and/or viscous re-magnetizations. Moreover, the use of site-mean data led to an additional statistical bias by giving equal weight to time-averaged and non-time-averaged data. When the paleointensity overestimates are removed, and the study-mean data are used instead of site-mean data, the Precambrian database does not indicate a robust change in geomagnetic field intensity during the Mesoproterozoic. Our analyses indicate that the presently available paleointensity data of Mesoproterozoic age are insufficient in number and quality to constrain the timing of solid inner core formation, or the outstanding problem of core thermal conductivity. More promising available data sets that reflect long-term core structure are geomagnetic reversal rate and field morphology. The latter suggests changes that may reflect differences in Archean to Proterozoic core stratification, whereas the former suggest an interval of geodynamo hyperactivity at ca 550 Ma.

  2. Record Club

    CERN Multimedia

    Record Club

    2012-01-01

      March  Selections By the time this appears, we will have added a number of new CDs and DVDs into the Club. You will find the full lists at http://cern.ch/record.club; select the "Discs of the Month" button on the left panel of the web page and then Mar 2012. New films include recent releases such as Johnny English 2, Bad Teacher, Cowboys vs Aliens, and Super 8. We are also starting to acquire some of the classic films we missed when we initiated the DVD section of the club, such as appeared in a recent Best 100 Films published by a leading UK magazine; this month we have added Spielberg’s Jaws and Scorsese’s Goodfellas. If you have your own ideas on what we are missing, let us know. For children we have no less than 8 Tin-Tin DVDs. And if you like fast moving pop music, try the Beyonce concert DVD. New CDs include the latest releases from Paul McCartney, Rihanna and Amy Winehouse. There is a best of Mylene Farmer, a compilation from the NRJ 201...

  3. Comodules over semiperfect corings

    CERN Document Server

    Caenepeel, S

    2011-01-01

    We discuss when the Rat functor associated to a coring satisfying the left $\\alpha$-condition is exact. We study the category of comodules over a semiperfect coring. We characterize semiperfect corings over artinian rings and over qF-rings.

  4. Coring Sample Acquisition Tool

    Science.gov (United States)

    Haddad, Nicolas E.; Murray, Saben D.; Walkemeyer, Phillip E.; Badescu, Mircea; Sherrit, Stewart; Bao, Xiaoqi; Kriechbaum, Kristopher L.; Richardson, Megan; Klein, Kerry J.

    2012-01-01

    A sample acquisition tool (SAT) has been developed that can be used autonomously to sample drill and capture rock cores. The tool is designed to accommodate core transfer using a sample tube to the IMSAH (integrated Mars sample acquisition and handling) SHEC (sample handling, encapsulation, and containerization) without ever touching the pristine core sample in the transfer process.

  5. An annual layer counted ice-core chronology from EDML, Antarctica, over the termination of the last glacial

    Science.gov (United States)

    Winstrup, Mai; Vinther, Bo M.; Svensson, Anders M.; Clausen, Henrik B.; Rasmussen, Sune O.; Fudge, Tj; Steig, Eric J.; Wegner, Anna; Kipfstuhl, Sepp

    2013-04-01

    Accurate and consistent timescales for paleoclimate records are crucial for advancing our understanding of the governing mechanisms and inter-hemispheric coupling involved in rapid climate change. For ice cores, very high-resolution chronologies can be established far back in time by identifying and counting annual layers in the ice core records. This is in particular true for the Greenland ice cores, for which the relatively high accumulation rates act to preserve the annual signal to great depths. The Greenland Ice Core Chronology 2005 (GICC05) is based on annual layer counts in data records from multiple Greenland ice cores, and it reaches back to 60 kyr BP. In Antarctica, only few ice core locations have sufficiently high accumulation rates for the annual signal in the ice core data to be maintained back into the last glacial. An annual layer counted timescale (WDC06A-7) reaching back to 30 kyr BP was recently completed for WAIS Divide, West Antarctica. Overall, the timescale is in good agreement with GICC05 within their respective uncertainties. Over the last glacial termination, however, significant discrepancies exist between the two chronologies, which cannot be reconciled within the specified uncertainty of the respective annual layer counts. Here, we present an independent annual layer counted chronology for the EPICA ice core from Dronning Maud Land (EDML), Antarctica, over the termination of the last glacial (10-15 kyr BP). The chronology is based on the annual signal visible in high-resolution impurity records and electrical conductivity measurements (liquid conductivity, DEP). The timescale is constructed using a novel Bayesian framework for multi-parameter annual layer counting in ice core records, which originates from sophisticated speech-recognition algorithms. It provides an objective estimate of the most likely number of layers within a section, as well as a confidence interval judging the uncertainty involved in layer identification. Resulting

  6. Core-size-dependent catalytic properties of bimetallic Au/Ag core-shell nanoparticles.

    Science.gov (United States)

    Haldar, Krishna Kanta; Kundu, Simanta; Patra, Amitava

    2014-12-24

    Bimetallic core-shell nanoparticles have recently emerged as a new class of functional materials because of their potential applications in catalysis, surface enhanced Raman scattering (SERS) substrate and photonics etc. Here, we have synthesized Au/Ag bimetallic core-shell nanoparticles with varying the core diameter. The red-shifting of the both plasmonic peaks of Ag and Au confirms the core-shell structure of the nanoparticles. Transmission electron microscopy (TEM) analysis, line scan EDS measurement and UV-vis study confirm the formation of core-shell nanoparticles. We have examined the catalytic activity of these core-shell nanostructures in the reaction between 4-nitrophenol (4-NP) and NaBH4 to form 4-aminophenol (4-AP) and the efficiency of the catalytic reaction is found to be increased with increasing the core size of Au/Ag core-shell nanocrystals. The catalytic efficiency varies from 41.8 to 96.5% with varying core size from 10 to 100 nm of Au/Ag core-shell nanoparticles, and the Au100/Ag bimetallic core-shell nanoparticle is found to be 12-fold more active than that of the pure Au nanoparticles with 100 nm diameter. Thus, the catalytic properties of the metal nanoparticles are significantly enhanced because of the Au/Ag core-shell structure, and the rate is dependent on the size of the core of the nanoparticles.

  7. 24-h core temperature in obese and lean men and women.

    Science.gov (United States)

    Hoffmann, Mindy E; Rodriguez, Sarah M; Zeiss, Dinah M; Wachsberg, Kelley N; Kushner, Robert F; Landsberg, Lewis; Linsenmeier, Robert A

    2012-08-01

    Maintenance of core temperature is a major component of 24-h energy expenditure, and its dysregulation could contribute to the pathophysiology of obesity. The relationship among temperature, sex, and BMI, however, has not been fully elucidated in humans. This study investigated core temperature in obese and lean individuals at rest, during 20-min exercise, during sleep, and after food consumption. Twelve lean (18.5-24.9 kg/m(2)) and twelve obese (30.0-39.9 kg/m(2)) healthy participants, ages 25-40 years old, were admitted overnight in a clinical research unit. Females were measured in the follicular menstrual phase. Core temperature was measured every minute for 24 h using the CorTemp system, a pill-sized sensor that measures core temperature while in the gastrointestinal tract and delivers the measurement via a radio signal to an external recorder. Core temperature did not differ significantly between the obese and lean individuals at rest, postmeals, during exercise, or during sleep (P > 0.5), but core temperature averaged over the entire study was significantly higher (0.1-0.2 °C) in the obese (P = 0.023). Each individual's temperature varied considerably during the study, but at all times, and across the entire study, women were ~0.4 °C warmer than men (P meals.

  8. Developing a theory of the strategic core of teams: a role composition model of team performance.

    Science.gov (United States)

    Humphrey, Stephen E; Morgeson, Frederick P; Mannor, Michael J

    2009-01-01

    Although numerous models of team performance have been articulated over the past 20 years, these models have primarily focused on the individual attribute approach to team composition. The authors utilized a role composition approach, which investigates how the characteristics of a set of role holders impact team effectiveness, to develop a theory of the strategic core of teams. Their theory suggests that certain team roles are most important for team performance and that the characteristics of the role holders in the "core" of the team are more important for overall team performance. This theory was tested in 778 teams drawn from 29 years of major league baseball (1974'-2002). Results demonstrate that although high levels of experience and job-related skill are important predictors of team performance, the relationships between these constructs and team performance are significantly stronger when the characteristics are possessed by core role holders (as opposed to non-core role holders). Further, teams that invest more of their financial resources in these core roles are able to leverage such investments into significantly improved performance. These results have implications for team composition models, as they suggest a new method for considering individual contributions to a team's success that shifts the focus onto core roles. (PsycINFO Database Record (c) 2009 APA, all rights reserved).

  9. Banded transformer cores

    Science.gov (United States)

    Mclyman, C. W. T. (Inventor)

    1974-01-01

    A banded transformer core formed by positioning a pair of mated, similar core halves on a supporting pedestal. The core halves are encircled with a strap, selectively applying tension whereby a compressive force is applied to the core edge for reducing the innate air gap. A dc magnetic field is employed in supporting the core halves during initial phases of the banding operation, while an ac magnetic field subsequently is employed for detecting dimension changes occurring in the air gaps as tension is applied to the strap.

  10. Core formation in silicate bodies

    Science.gov (United States)

    Nimmo, F.; O'Brien, D. P.; Kleine, T.

    2008-12-01

    Differentiation of a body into a metallic core and silicate mantle occurs most efficiently if temperatures are high enough to allow at least the metal to melt [1], and is enhanced if matrix deformation occurs [2]. Elevated temperatures may occur due to either decay of short-lived radio-isotopes, or gravitational energy release during accretion [3]. For bodies smaller than the Moon, core formation happens primarily due to radioactive decay. The Hf-W isotopic system may be used to date core formation; cores in some iron meteorites and the eucrite parent body (probably Vesta) formed within 1 My and 1-4~My of solar system formation, respectively [4]. These formation times are early enough to ensure widespread melting and differentiation by 26Al decay. Incorporation of Fe60 into the core, together with rapid early mantle solidification and cooling, may have driven early dynamo activity on some bodies [5]. Iron meteorites are typically depleted in sulphur relative to chondrites, for unknown reasons [6]. This depletion contrasts with the apparently higher sulphur contents of cores in larger planetary bodies, such as Mars [7], and also has a significant effect on the timing of core solidification. For bodies of Moon-size and larger, gravitational energy released during accretion is probably the primary cause of core formation [3]. The final stages of accretion involve large, stochastic collisions [8] between objects which are already differentiated. During each collision, the metallic cores of the colliding objects merge on timescales of a few hours [9]. Each collision will reset the Hf-W isotopic signature of both mantle and core, depending on the degree to which the impactor core re-equilibrates with the mantle of the target [10]. The re-equilibration efficiency depends mainly on the degree to which the impactor emulsifies [11], which is very uncertain. Results from N-body simulations [8,12] suggest that significant degrees of re- equilibration are required [4,10]. Re

  11. A latency analysis for M2M and OG-like traffic patterns in different HSPA core network configurations

    Directory of Open Access Journals (Sweden)

    M. V. Popović

    2014-11-01

    Full Text Available In this paper we present an analysis intended to reveal possible impacts of core network features on latency for modelled M2M and Online Gaming traffic. Simulations were performed in a live 3G/HSPA network. Test traffic simulating multiplayer real-time games and M2M applications was generated on 10 mobile phones in parallel, sending data to a remote server. APNs with different combinations of hardware and features (proxy server, different GGSNs and firewalls, usage of Service Awareness feature were chosen. The traffic was recorded on the Gn interface in the mobile core. The goal of experiments was to evaluate any eventually significant variation of average recorded RTTs in the core part of mobile network that would clearly indicate either the impact of used APN on delay for a specific traffic pattern, or selectivity of the APN towards different traffic patterns.

  12. Recorded seismic response of Pacific Park Plaza. II. System identification

    Science.gov (United States)

    Safak, F.; Celebi, M.

    1992-01-01

    This is the second of two companion papers on the recorded seismic response of the Pacific Park Plaza building, in Emeryville, Calif., during the October 17, 1989, Ms = 7.1 (surface-wave magnitude) Loma Prieta earthquake. In this second part, the recorded data are analyzed in more detail by using system-identification techniques. The three-dimensional behavior and the coupled modes of the building are determined, and the effects of soil-structure interaction are investigated. The study shows that the response of the building is nonlinear at the beginning, and becomes linear after 17 sec into the earthquake. The dominant motion of the building follows an elliptical path oriented in the southeast-northwest direction. Some of the modes are complex, with nonproportional damping, and there are phase differences among modal response components. The fundamental mode of the building is a translation in the southeast-northwest direction at 0.4 Hz, with 13% damping. The wing displacements relative to the center core are large, about 50% of the center core displacements, and indicate significant torsion in the center core. The soil-structure interaction is characterized by a vibration at 0.7 Hz. This is believed to be the fundamental frequency of the surrounding soil medium. The rocking motions of the building are negligible.

  13. Abundant climatic information in water stable isotope record from a maritime glacier on southeastern Tibetan Plateau

    Science.gov (United States)

    Zhao, Huabiao; Xu, Baiqing; Li, Zhen; Wang, Mo; Li, Jiule; Zhang, Xiaolong

    2016-04-01

    Climatic significance of ice core stable isotope record in the Himalayas and southern Tibetan Plateau (TP), where the climate is alternately influenced by Indian summer monsoon and mid-latitude westerlies, is still debated. A newly drilled Zuoqiupu ice core from a temperate maritime glacier on the southeastern TP covering 1942-2011 is investigated in terms of the relationships between δ18O and climate parameters. Distinct seasonal variation of δ18O is observed due to high precipitation amount in this area. Thus the monsoon (June to September) and non-monsoon (October to May) δ18O records are reconstructed, respectively. The temperature effect is identified in the annual δ18O record, which is predominantly contributed by temperature control on the non-monsoon precipitation δ18O record. Conversely, the negative correlation between annual δ18O record and precipitation amount over part of Northeast India is mostly contributed by the monsoon precipitation δ18O record. The variation of monsoon δ18O record is greatly impacted by the Indian summer monsoon strength, while that of non-monsoon δ18O record is potentially associated with the mid-latitude westerly activity. The relationship between Zuoqiupu δ18O record and Sea Surface Temperature (SST) is found to be inconsistent before and after the climate shift of 1976/1977. In summer monsoon season, the role of SST in the monsoon δ18O record is more important in eastern equatorial Pacific Ocean and tropical Indian Ocean before and after the shift, respectively. In non-monsoon season, however, the Atlantic Multidecadal Oscillation has a negative impact before but positive impact after the climate shift on the non-monsoon δ18O record.

  14. Recent climate tendencies on an East Antarctic ice shelf inferred from a shallow firn core network

    Science.gov (United States)

    Schlosser, E; Anschütz, H; Divine, D; Martma, T; Sinisalo, A; Altnau, S; Isaksson, E

    2014-01-01

    Nearly three decades of stable isotope ratios and surface mass balance (SMB) data from eight shallow firn cores retrieved at Fimbul Ice Shelf, East Antarctica, in the Austral summers 2009–2011 have been investigated. An additional longer core drilled in 2000/2001 extends the series back to the early eighteenth century. Isotope ratios and SMB from the stacked record of all cores were also related to instrumental temperature data from Neumayer Station on Ekström Ice Shelf. Since the second half of the twentieth century, the SMB shows a statistically significant negative trend, whereas the δ18O of the cores shows a significant positive trend. No trend is found in air temperature at the nearest suitable weather station, Neumayer (available since 1981). This does not correspond to the statistically significant positive trend in Southern Annular Mode (SAM) index, which is usually associated with a cooling of East Antarctica. SAM index and SMB are negatively correlated, which might be explained by a decrease in meridional exchange of energy and moisture leading to lower precipitation amounts. Future monitoring of climate change on the sensitive Antarctic ice shelves is necessary to assess its consequences for sea level change. Key Points Mass balance and stable oxygen isotope ratios from shallow firn cores Decreasing trend in surface mass balance, no trend in stable isotopes Negative correlation between SAM and SMB PMID:25821663

  15. Astrobiological Significance of Microbial Extremophiles

    Science.gov (United States)

    Pikuta, Elena V.; Hoover, Richard B.

    2007-01-01

    The microflora of the cryosphere of planet Earth provides the best analogs for life forms that might be found in the permafrost or polar ice caps of Mars, near the surface of the cometary nuclei, or in the liquid water beneath and the ice crusts of icy moons of Jupiter and Saturn. The importance of study alkaliphilic microorganisms for astrobiology was enhanced by the findings of abundant carbonates and carbonate globules rimmed with possibly biogenic magnetites in association with the putative microfossils in the ALH84001 meteorite. Although the ALH84001 "nanofossils" were to small and simple to be unambiguously recognized as biogenic, they stimulated Astrobiology research and studies of microbial extremophiles and biomarkers in ancient rocks and meteorites. Recent studies of CI and CM carbonaceous meteorites have resulted in the detection of the well-preserved mineralized remains of coccoidal and filamentous microorganisms in cyanobacterial mats. Energy Dispersive X-ray Analysis has shown anomalous biogenic element ratios clearly indicating they are not recent biological contaminants. This paper reviews microbial extremophiles in context of their significance to Astrobiology. The study of halophilic microorganisms was started from work with saline soils and lakes, and one of the record of good growth for Haloferax mediterranei was shown at 30 percent NaC1. Although alkali-tolerant nitrifying bacteria had previously been reported, the first described alkaliphilic microorganism was the bacterium Streptococcus faecalis. Halophilic and alkaliphilic forms are relevant to conditions that might be found in closed impact basins and craters on Mars filled with evaporite deposits. The first obligately acidophilic bacterium described was Acidithiobacillus ferrooxydans (formally Thiobacillus ferrooxidans). Later thermophilic lithotrophic acidophiles were found, and the hyperacidophilic moderately thermophilic species of the genus Picrophilus were found to grow at negative p

  16. Volcanic synchronisation between the EPICA Dome C and Vostok ice cores (Antarctica 0–145 kyr BP

    Directory of Open Access Journals (Sweden)

    R. Udisti

    2012-06-01

    Full Text Available This study aims at refining the synchronisation between the EPICA Dome C (EDC and Vostok ice cores in the time interval 0–145 kyr BP by using the volcanic signatures. 102 common volcanic events were identified by using continuous electrical conductivity (ECM, di-electrical profiling (DEP and sulfate measurements while trying to minimize the distortion of the glaciological chronologies. This is an update and a continuation of previous works performed over the 0–45 kyr interval that provided 56 tie points to the ice core chronologies (Udisti et al., 2004. This synchronisation will serve to establish Antarctic Ice Core Chronology 2012, the next synchronised Antarctic dating. A change of slope in the EDC-depth/Vostok-depth diagram is probably related to a change of accumulation regime as well as to a change of ice thickness upstream of the Lake Vostok, but we did not invoke any significant temporal change of surface accumulation at EDC relative to Vostok. No significant phase difference is detected between the EDC and Vostok isotopic records, but depth shifts between the Vostok 3G and 5G ice cores prevent from looking at this problem accurately. Three possible candidates for the Toba volcanic super-eruption ~73 kyr ago are suggested in the Vostok and EDC volcanic records. Neither the ECM, DEP nor the sulfate fingerprints for these 3 events are significantly larger than many others in the records.

  17. High-resolution records of the beryllium-10 solar activity proxy in ice from Law Dome, East Antarctica: measurement, reproducibility and principal trends

    Directory of Open Access Journals (Sweden)

    J. B. Pedro

    2011-02-01

    Full Text Available Three near-monthly resolution 10Be records are presented from the Dome Summit South (DSS ice core site, Law Dome, East Antarctica. The chemical preparation and Accelerator Mass Spectrometer (AMS measurement of these records is described. The reproducibility of 10Be records at DSS is assessed through intercomparison of the ice core data with data from two previously published and contemporaneous snow pits. We find generally good agreement between the five records, comparable to that observed between other trace chemical records from the site. This result allays concerns raised by a previous Antarctic study (Moraal et al., 2005 about poor reproducibility of ice core 10Be records. A single composite series is constructed from the three ice cores providing a monthly-resolved record of 10Be concentrations at DSS over the past decade (1999 to 2009. To our knowledge, this is the first published ice core data spanning the recent exceptional solar minimum of solar cycle 23. 10Be concentrations are significantly correlated to the cosmic ray flux recorded by the McMurdo neutron monitor (rxy = 0.64, with 95% CI of 0.53 to 0.71, suggesting that solar modulation of the atmospheric production rate may explain up to ~40% of the variance in 10Be concentrations at DSS. Sharp concentration peaks occur in most years during the summer-to-autumn, possibly caused by stratospheric incursions. Our results underscore the presence of both production and meteorological signals in ice core 10Be data.

  18. High-resolution records of the beryllium-10 solar activity proxy in ice from Law Dome, East Antarctica: measurement, reproducibility and principal trends

    Directory of Open Access Journals (Sweden)

    J. B. Pedro

    2011-07-01

    Full Text Available Three near-monthly resolution 10Be records are presented from the Dome Summit South (DSS ice core site, Law Dome, East Antarctica. The chemical preparation and Accelerator Mass Spectrometer (AMS measurement of these records is described. The reproducibility of 10Be records at DSS is assessed through intercomparison of the ice core data with data from two previously published and contemporaneous snow pits. We find generally good agreement between the five records, comparable to that observed between other trace chemical records from the site. This result allays concerns raised by a previous Antarctic study (Moraal et al., 2005 about poor reproducibility of ice core 10Be records. A single composite series is constructed from the three ice cores providing a monthly-resolved record of 10Be concentrations at DSS over the past decade (1999 to 2009. To our knowledge, this is the first published ice core data spanning the recent exceptional solar minimum of solar cycle 23. 10Be concentrations are significantly correlated to the cosmic ray flux recorded by the McMurdo neutron monitor (rxy = 0.64, with 95 % CI of 0.53 to 0.71, suggesting that solar modulation of the atmospheric production rate may explain up to ~40 % of the variance in 10Be concentrations at DSS. Sharp concentration peaks occur in most years during the summer-to-autumn, possibly caused by stratospheric incursions. Our results underscore the presence of both production and meteorological signals in ice core 10Be data.

  19. 支持多核并行程序确定性重放的高效访存冲突记录方法%High Efficient Memory Race Recording Scheme for Parallel Program Deterministic Replay Under Multi-Core Architecture

    Institute of Scientific and Technical Information of China (English)

    刘磊; 黄河; 唐志敏

    2012-01-01

    多核系统中并行程序执行过程的不确定性给程序调试带来了很大的困难.准确记录初始执行中冲突访存的次序是并行程序确定性重放的基础.提出了通过建立精确happens-before关系记录访存冲突的方法.此方法利用简洁高效的地址冲突检测机制确定冲突访存操作在执行中所处happens-before序关系的位置,可以抑制部分记录信息的产生,从而有效减少记录信息.与其他方式方法相比,可以进一步压缩17%的记录条数.采用逻辑向量时钟描述冲突访存操作间的happens-before关系,与采用标量时钟相比,可以避免happens-before关系的误识,降低重放执行时并行度的损失.%Current shared memory multi-core and multiprocessor systems are nondeterministic. When these systems execute a multithreaded application, even if supplied with the same input, they could produce a different output each time. It frustrates debugging and limits the ability to properly test multithreaded code, and is becoming a major stumbling block to the much-needed widespread adoption of parallel programming. The support for deterministic replay of multithreaded execution is greatly helpful in finding concurrency bugs. A memory race recording scheme, named Rainbow, is proposed. Its core idea is to make inter-thread communications fully deterministic. The unique feature of Rainbow is that it precisely sets up happens-before relationships between conflicting memory operations among different threads. By using effective, bloom-filter based, coherence history queue, Rainbow removes redundant happens-before relations implied in the already generated log and enables a compact log. Rainbow adds the modest hardware to the base multi-core processors, and the coherence protocol is unmodified. The analysis results show that Rainbow reduces the log size by 17% of a state-of-the-art scheme, and the records execution speed is similar to that of release consistency (RC) execution

  20. The core paradox.

    Science.gov (United States)

    Kennedy, G. C.; Higgins, G. H.

    1973-01-01

    Rebuttal of suggestions from various critics attempting to provide an escape from the seeming paradox originated by Higgins and Kennedy's (1971) proposed possibility that the liquid in the outer core was thermally stably stratified and that this stratification might prove a powerful inhibitor to circulation of the outer core fluid of the kind postulated for the generation of the earth's magnetic field. These suggestions are examined and shown to provide no reasonable escape from the core paradox.

  1. K-core inflation

    OpenAIRE

    Alexander L. Wolman

    2011-01-01

    K-core inflation is a new class of underlying inflation measures. The two most popular measures of underlying inflation are core inflation and trimmed mean inflation. The former removes fixed categories of goods and services (food and energy) from the inflation calculation, and the latter removes fixed percentiles of the weighted distribution of price changes. In contrast, k-core inflation specifies a size of relative price change to be removed from the inflation calculation. Thus, the catego...

  2. Infiltration characteristics of non-aqueous phase liquids in undisturbed loessal soil cores

    Institute of Scientific and Technical Information of China (English)

    WANG Yunqiang; SHAO Ming'an

    2009-01-01

    The widespread contamination of soils and aquifers by non-aqueous phase liquids (NAPL), such as crude oil, poses serious environmental and health hazards globally. Understanding the infiltration characteristics of NAPL in soil is crucial in mitigating or remediating soil contamination. The infiltration characteristics of crude and diesel oils into undisturbed loessal soil cores, collected in polymethyl methacrylate cylindrical columns, were investigated under a constant fluid head (3 cm) of either crude oil or diesel oil. The infiltration rate of both crude and diesel oils decreased exponentially as wetting depth increased with time. Soil core size and bulk density both had a significant effect on NAPL infiltration through the undisturbed soil cores; a smaller core size or a greater bulk density both reduced oil penetration to depth. Compacting soil in areas susceptible to oil spills may be an effective way to reduce contamination. The infiltration of NAPL into soil cores was spatially anisotropic and heterogeneous, thus recording the data at four points on the soil core is a good way to improve the accuracy of experimental results. Our results provided information about crude and diesel oils, rather than their components, and may have practical value for remediation of contaminated loessal soils.

  3. Sediment Core Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides instrumentation and expertise for physical and geoacoustic characterization of marine sediments. DESCRIPTION: The multisensor core logger measures...

  4. Sediment Core Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides instrumentation and expertise for physical and geoacoustic characterization of marine sediments.DESCRIPTION: The multisensor core logger measures...

  5. An improved continuous flow analysis system for high-resolution field measurements on ice cores.

    Science.gov (United States)

    Kaufmann, Patrik R; Federer, Urs; Hutterli, Manuel A; Bigler, Matthias; Schüpbach, Simon; Ruth, Urs; Schmitt, Jochen; Stocker, Thomas F

    2008-11-01

    Continuous flow analysis (CFA) is a well-established method to obtain information about impurity contents in ice cores as indicators of past changes in the climate system. A section of an ice core is continuously melted on a melter head supplying a sample water flow which is analyzed online. This provides high depth and time resolution of the ice core records and very efficient sample decontamination as only the inner part of the ice sample is analyzed. Here we present an improved CFA system which has been totally redesigned in view of a significantly enhanced overall efficiency and flexibility, signal quality, compactness, and ease of use. These are critical requirements especially for operations of CFA during field campaigns, e.g., in Antarctica or Greenland. Furthermore, a novel deviceto measure the total air content in the ice was developed. Subsequently, the air bubbles are now extracted continuously from the sample water flow for subsequent gas measurements.

  6. Disentangling natural and anthropogenic signals in lacustrine records: An example from the Ilan Plain, NE Taiwan

    Science.gov (United States)

    Huang, Jyh-Jaan; Huh, Chih-An; Wei, Kuo-Yen; Löwemark, Ludvig; Lin, Shu-Fen; Liao, Wen-Hsuan; Yang, Tien-Nan; Song, Sheng-Rong; Lee, Meng-Yang; Su, Chih-Chieh; Lee, Teh-Quei

    2016-11-01

    The impact of human activities has been increasing to a degree where humans now outcompete many natural processes. When interpreting environmental and climatic changes recorded in natural archives on historical time scales, it is therefore important to be able to disentangle the relative contribution of natural and anthropogenic processes. Lake Meihua on the Ilan Plain in northeastern Taiwan offers a particularly suitable opportunity to test how human activities known from historical records can be recorded in lacustrine sediment. For this purpose, three cores from Lake Meihua have been studied by a multiproxy approach, providing the first decadal-resolution lacustrine records covering the past 150 years in Taiwan. Profiles of excess 210Pb, 137Cs and 239,240Pu from two short cores (MHL-09-01 and MHL-11-02) allowed a precise chronology to be established. The presence of a yellow, earthy layer with lower levels of organic material coincide with the record of land development associated with the construction of the San-Chin-Gong Temple during AD 1970-1982. Furthermore, in the lower part of the cores, the upwards increasing trend of inc/coh, TOC, TOC/TN, and grain size, coupled with the palynological data (increase of Alnus, Mallotus, Trema and herbs) from the nearby core MHL-5A with radiocarbon chronology, suggest that the area surrounding the lake has been significantly affected by agricultural activities since the arrival of Chinese settlers around AD 1874. In sum, this study demonstrates that this suite of lacustrine sediments in northeastern Taiwan has recorded human activities in agreement with historical documents, and that different human activities will leave distinct sedimentological, geochemical, and palynological signatures in the sedimentary archives. Therefore, multiproxy reconstructions are important to capture the complex nature of human-environmental interactions. A better understanding of the weathering and erosion response to human activities can

  7. Chang'an Maid Walk Under the Spring Sunlight——On the Historical Significance of the novel,Strange Dream Recorded by Shen Ya-zhi%长安少女踏春阳——沈亚之《异梦录》的小说史意义

    Institute of Scientific and Technical Information of China (English)

    张同利

    2011-01-01

    《异梦录》在唐小说作品中颇具代表性,以之为切入点,可以对唐小说的创作过程、艺术和结构特征,以及它们在古代小说中的独特意义等有更深入的认识。%The novel,Strange Dream Recorded,can represent the characteristics of the fictions of Tang dynasty.If we take it as a starting point,we can have a deep understanding about the fictions of Tang,such as their writing process,feature of structure and unique significance in the ancient novels.

  8. Recent Problems of Transformer Core Design

    Science.gov (United States)

    Valkovic, Z.

    1988-01-01

    The paper describes the result of the investigations of the efficiency of power loss reduction in transformer cores made with high-permeability (HGO) and laser scribed (LS) grain-oriented electrical steels, and also the phenomena in three-limb three-phase cores with the so-called staggered T-joint design. The efficiency of the HGO material depends on core form and core induction. The efficiency is better for single-phase than for three-phase cores and also for higher induction. The localised efficiency of HGO material is not uniform and it is significantly lower in the yoke than in other parts. The efficiency of LS material (grade ZDKH) is better than that of the HGO material and also somewhat higher for single-phase than for three-phase cores. The localised flux distribution in the central limb of the core with staggered T-joint is more uniform and the content of higher harmonics is smaller than in the core with conventional V-45° T-joint. This results in a 13% loss reduction in the central limb and in a 4-5% reduction of total core loss.

  9. Effect of core stabilization exercises on functional disability in patients with chronic low back pain

    Directory of Open Access Journals (Sweden)

    Amila Kapetanovic

    2016-04-01

    Full Text Available Introduction: The aim of this study was to assess core stabilization exercise effects in reducing functional disability in patients with chronic low back pain (CLBP.Methods: This study included total of 90 patients aged 40 to 60 years. After a ten-day rehabilitation program the patients from an examination group (n = 30 performed home exercise program five times a week, patients from a first control group (n = 30 three times a week, while patients from a second control group (n = 30 did not perform the exercises at all. The patients performed core stabilization exercises of moderate intensity once a day in 30 minutes sessions. The patient's functional disability was estimated using the Oswestry Disability Index (ODI.Results: After two months of rehabilitation there was a statistically significant increase in functional ability in patients who performed the core stabilization exercises five times a week(p = 0.0001 and in patients who performed the core stabilization exercises three times per week (p = 0.0001. A statistically significant difference in functional ability was not recorded in patients who did not perform the exercises. The analysis of the average values of the ODI differences at the beginning and after two months of rehabilitation showed a statistically significant difference between the group who did not perform the exercises and the group who performed the core stabilization exercises three times a week (p = 0.0001, and between the group who did not perform the exercises and the group who performed the core stabilization exercises five times a week (p = 0.0001.Conclusions: The implementation of the core stabilization exercises leads to a reduction of functional disability in patients with CLBP.

  10. Ice Core Investigations

    Science.gov (United States)

    Krim, Jessica; Brody, Michael

    2008-01-01

    What can glaciers tell us about volcanoes and atmospheric conditions? How does this information relate to our understanding of climate change? Ice Core Investigations is an original and innovative activity that explores these types of questions. It brings together popular science issues such as research, climate change, ice core drilling, and air…

  11. Making an Ice Core.

    Science.gov (United States)

    Kopaska-Merkel, David C.

    1995-01-01

    Explains an activity in which students construct a simulated ice core. Materials required include only a freezer, food coloring, a bottle, and water. This hands-on exercise demonstrates how a glacier is formed, how ice cores are studied, and the nature of precision and accuracy in measurement. Suitable for grades three through eight. (Author/PVD)

  12. Ice Core Investigations

    Science.gov (United States)

    Krim, Jessica; Brody, Michael

    2008-01-01

    What can glaciers tell us about volcanoes and atmospheric conditions? How does this information relate to our understanding of climate change? Ice Core Investigations is an original and innovative activity that explores these types of questions. It brings together popular science issues such as research, climate change, ice core drilling, and air…

  13. Iowa Core Annual Report

    Science.gov (United States)

    Iowa Department of Education, 2015

    2015-01-01

    One central component of a great school system is a clear set of expectations, or standards, that educators help all students reach. In Iowa, that effort is known as the Iowa Core. The Iowa Core represents the statewide academic standards, which describe what students should know and be able to do in math, science, English language arts, and…

  14. Mars' core and magnetism.

    Science.gov (United States)

    Stevenson, D J

    2001-07-12

    The detection of strongly magnetized ancient crust on Mars is one of the most surprising outcomes of recent Mars exploration, and provides important insight about the history and nature of the martian core. The iron-rich core probably formed during the hot accretion of Mars approximately 4.5 billion years ago and subsequently cooled at a rate dictated by the overlying mantle. A core dynamo operated much like Earth's current dynamo, but was probably limited in duration to several hundred million years. The early demise of the dynamo could have arisen through a change in the cooling rate of the mantle, or even a switch in convective style that led to mantle heating. Presently, Mars probably has a liquid, conductive outer core and might have a solid inner core like Earth.

  15. Dynamic Responses of the Earth's Outer Core to Assimilation of Observed Geomagnetic Secular Variation

    Science.gov (United States)

    Kuang, Weijia; Tangborn, Andrew

    2014-01-01

    Assimilation of surface geomagnetic observations and geodynamo models has advanced very quickly in recent years. However, compared to advanced data assimilation systems in meteorology, geomagnetic data assimilation (GDAS) is still in an early stage. Among many challenges ranging from data to models is the disparity between the short observation records and the long time scales of the core dynamics. To better utilize available observational information, we have made an effort in this study to directly assimilate the Gauss coefficients of both the core field and its secular variation (SV) obtained via global geomagnetic field modeling, aiming at understanding the dynamical responses of the core fluid to these additional observational constraints. Our studies show that the SV assimilation helps significantly to shorten the dynamo model spin-up process. The flow beneath the core-mantle boundary (CMB) responds significantly to the observed field and its SV. The strongest responses occur in the relatively small scale flow (of the degrees L is approx. 30 in spherical harmonic expansions). This part of the flow includes the axisymmetric toroidal flow (of order m = 0) and non-axisymmetric poloidal flow with m (is) greater than 5. These responses can be used to better understand the core flow and, in particular, to improve accuracies of predicting geomagnetic variability in future.

  16. The t-core of an s-core

    OpenAIRE

    Fayers, Matthew

    2010-01-01

    We consider the $t$-core of an $s$-core partition, when $s$ and $t$ are coprime positive integers. Olsson has shown that the $t$-core of an $s$-core is again an $s$-core, and we examine certain actions of the affine symmetric group on $s$-cores which preserve the $t$-core of an $s$-core. Along the way, we give a new proof of Olsson's result. We also give a new proof of a result of Vandehey, showing that there is a simultaneous $s$- and $t$-core which contains all others.

  17. The t-core of an s-core

    OpenAIRE

    Fayers, Matthew

    2010-01-01

    We consider the $t$-core of an $s$-core partition, when $s$ and $t$ are coprime positive integers. Olsson has shown that the $t$-core of an $s$-core is again an $s$-core, and we examine certain actions of the affine symmetric group on $s$-cores which preserve the $t$-core of an $s$-core. Along the way, we give a new proof of Olsson's result. We also give a new proof of a result of Vandehey, showing that there is a simultaneous $s$- and $t$-core which contains all others.

  18. Korrelasjon mellom core styrke, core stabilitet og utholdende styrke i core

    OpenAIRE

    Berg-Olsen, Andrea Marie; Fugelsøy, Eivor; Maurstad, Ann-Louise

    2010-01-01

    Formålet med studien var å se hvilke korrelasjon det er mellom core styrke, core stabilitet og utholdende styrke i core. Testingen bestod av tre hoveddeler hvor vi testet core styrke, core stabilitet og utholdende styrke i core. Innenfor core styrke og utholdende styrke i core ble tre ulike tester utført. Ved måling av core stabilitet ble det gjennomført kun en test. I core styrke ble isometrisk abdominal fleksjon, isometrisk rygg ekstensjon og isometrisk lateral fleksjon testet. Sit-ups p...

  19. Korrelasjon mellom core styrke, core stabilitet og utholdende styrke i core

    OpenAIRE

    Berg-Olsen, Andrea Marie; Fugelsøy, Eivor; Maurstad, Ann-Louise

    2010-01-01

    Formålet med studien var å se hvilke korrelasjon det er mellom core styrke, core stabilitet og utholdende styrke i core. Testingen bestod av tre hoveddeler hvor vi testet core styrke, core stabilitet og utholdende styrke i core. Innenfor core styrke og utholdende styrke i core ble tre ulike tester utført. Ved måling av core stabilitet ble det gjennomført kun en test. I core styrke ble isometrisk abdominal fleksjon, isometrisk rygg ekstensjon og isometrisk lateral fleksjon testet. Sit-ups p...

  20. Earth's inner core: Innermost inner core or hemispherical variations?

    NARCIS (Netherlands)

    Lythgoe, K. H.; Deuss, A.; Rudge, J. F.; Neufeld, J. A.

    2014-01-01

    The structure of Earth's deep inner core has important implications for core evolution, since it is thought to be related to the early stages of core formation. Previous studies have suggested that there exists an innermost inner core with distinct anisotropy relative to the rest of the inner core.

  1. Earth's inner core: Innermost inner core or hemispherical variations?

    NARCIS (Netherlands)

    Lythgoe, K. H.; Deuss, A.; Rudge, J. F.; Neufeld, J. A.

    2014-01-01

    The structure of Earth's deep inner core has important implications for core evolution, since it is thought to be related to the early stages of core formation. Previous studies have suggested that there exists an innermost inner core with distinct anisotropy relative to the rest of the inner core.

  2. 根据日本中部琵琶湖深井孢粉资料重建第四纪古植被和古气候及全球古气候对比%PALAEOVEGETATION AND PALAEOCLIMATE DURING THE QUATERNARY PERIOD BASED ON THE LONG CORES FROM LAKE BIWA, CENTRAL JAPAN, AND GLOBAL CORRELATION OF THE PALAEOCLIMATE RECORDS

    Institute of Scientific and Technical Information of China (English)

    藤则雄

    2003-01-01

    根据日本中部琵琶湖深井钻探资料研究了过去3Ma的古植被、地层及古气候.由湖底取得的200m和1 400m样品的孢粉组合可分别划分出19个和37个带,反映了湖区及其周围自晚上新世以来的古植被和古气候演变史.在冰期阶时琵琶湖附近山区的典型植被为亚北极带,低地为冷温带.而在间冰期阶里山区一般为温带或冷温带植被,低地则主要由落叶和常绿树组成的温带和暖温带的植被.在进行过去3Ma古植被、古气候演变对比中,当地古气候史和以下资料显示出明显的一致,例如加勒比海、西太平洋及赤道海洋的氧同位素资料,地中海西部(Mallorca)的沉积旋回,欧洲中部的风成沉积序列,日本关东和新几内亚的海平面变化记录,以及在南美波哥大高地和以色列死海裂谷根据孢粉得出的古气候变化记录.%Investigation was carried out on the palaeovegetation, stratigraphy and palaeoclimate in the last 3 Ma based onthe long cores from the Lake Biwa, Central Japan. Samples of 200-meter and 1400-meter cores obtained from the bottom of thelake yield nineteen and thirty-seven pollen zones respectively showing the palaeovegetational and palaeoclimatic changes inand around the lake since the late Pliocene period. During the glacial stages or stadials, typical vegetation of the subpolar zoneoccurred in the mountainous area around Lake Biwa. While in the lowland area in and around the lake, characteristic plants ofthe Cool Temperate zone occurred. During the interglacial stages or interstadials the vegetation of the mountainous area wasgenerally characterized by plants of the Temperate zone and/or Cool Temperate zone, while in the lowland area the vegetationwas composed mainly of deciduous and evergreen broad-leaved trees of the Temperate and Warm Temperate zones. In theglobal correlation from the viewpoints of palaeovegetation and palaeoclimate changes during the last 3 Ma since the late

  3. Multi-Core Processor Memory Contention Benchmark Analysis Case Study

    Science.gov (United States)

    Simon, Tyler; McGalliard, James

    2009-01-01

    Multi-core processors dominate current mainframe, server, and high performance computing (HPC) systems. This paper provides synthetic kernel and natural benchmark results from an HPC system at the NASA Goddard Space Flight Center that illustrate the performance impacts of multi-core (dual- and quad-core) vs. single core processor systems. Analysis of processor design, application source code, and synthetic and natural test results all indicate that multi-core processors can suffer from significant memory subsystem contention compared to similar single-core processors.

  4. Subannual layer variability in Greenland firn cores

    Science.gov (United States)

    Kjær, Helle Astrid; Vallelonga, Paul; Vinther, Bo; Winstrup, Mai; Simonsen, Marius; Maffezzoli, Niccoló; Jensen, Camilla Marie

    2017-04-01

    Ice cores are used to infer information about the past and modern techniques allow for high resolution (CFA) of the ice. Such analysis is often used to inform on annual layers to constrain dating of ice cores, but can also be extended to provide information on sub-annual deposition patterns. In this study we use available high resolution data from multiple shallow cores around Greenland to investigate the seasonality and trends in the most often continuously measured components sodium, insoluble dust, calcium, ammonium and conductivity (or acidity) from 1800 AD to today. We evaluate the similarities and differences between the records and discuss the causes from different sources and transport to deposition and post-deposition effects over differences in measurement set up. Further we add to the array of cores already published with measurements from the newly drilled ReCAP ice core from a coastal ice cap in eastern Greenland and from a shallow core drilled at the high accumulation site at the Greenland South Dome.

  5. IGCSE core mathematics

    CERN Document Server

    Wall, Terry

    2013-01-01

    Give your core level students the support and framework they require to get their best grades with this book dedicated to the core level content of the revised syllabus and written specifically to ensure a more appropriate pace. This title has been written for Core content of the revised Cambridge IGCSE Mathematics (0580) syllabus for first teaching from 2013. ? Gives students the practice they require to deepen their understanding through plenty of practice questions. ? Consolidates learning with unique digital resources on the CD, included free with every book. We are working with Cambridge

  6. Core shroud corner joints

    Science.gov (United States)

    Gilmore, Charles B.; Forsyth, David R.

    2013-09-10

    A core shroud is provided, which includes a number of planar members, a number of unitary corners, and a number of subassemblies each comprising a combination of the planar members and the unitary corners. Each unitary corner comprises a unitary extrusion including a first planar portion and a second planar portion disposed perpendicularly with respect to the first planar portion. At least one of the subassemblies comprises a plurality of the unitary corners disposed side-by-side in an alternating opposing relationship. A plurality of the subassemblies can be combined to form a quarter perimeter segment of the core shroud. Four quarter perimeter segments join together to form the core shroud.

  7. Probabilistic sequence alignment of stratigraphic records

    Science.gov (United States)

    Lin, Luan; Khider, Deborah; Lisiecki, Lorraine E.; Lawrence, Charles E.

    2014-10-01

    The assessment of age uncertainty in stratigraphically aligned records is a pressing need in paleoceanographic research. The alignment of ocean sediment cores is used to develop mutually consistent age models for climate proxies and is often based on the δ18O of calcite from benthic foraminifera, which records a global ice volume and deep water temperature signal. To date, δ18O alignment has been performed by manual, qualitative comparison or by deterministic algorithms. Here we present a hidden Markov model (HMM) probabilistic algorithm to find 95% confidence bands for δ18O alignment. This model considers the probability of every possible alignment based on its fit to the δ18O data and transition probabilities for sedimentation rate changes obtained from radiocarbon-based estimates for 37 cores. Uncertainty is assessed using a stochastic back trace recursion to sample alignments in exact proportion to their probability. We applied the algorithm to align 35 late Pleistocene records to a global benthic δ18O stack and found that the mean width of 95% confidence intervals varies between 3 and 23 kyr depending on the resolution and noisiness of the record's δ18O signal. Confidence bands within individual cores also vary greatly, ranging from ~0 to >40 kyr. These alignment uncertainty estimates will allow researchers to examine the robustness of their conclusions, including the statistical evaluation of lead-lag relationships between events observed in different cores.

  8. Institutional management of core facilities during challenging financial times.

    Science.gov (United States)

    Haley, Rand

    2011-12-01

    The economic downturn is likely to have lasting effects on institutions of higher education, prioritizing proactive institutional leadership and planning. Although by design, core research facilities are more efficient and effective than supporting individual pieces of research equipment, cores can have significant underlying financial requirements and challenges. This paper explores several possible institutional approaches to managing core facilities during challenging financial times.

  9. Core body temperature in obesity123

    Science.gov (United States)

    Heikens, Marc J; Gorbach, Alexander M; Eden, Henry S; Savastano, David M; Chen, Kong Y; Skarulis, Monica C

    2011-01-01

    Background: A lower core body temperature set point has been suggested to be a factor that could potentially predispose humans to develop obesity. Objective: We tested the hypothesis that obese individuals have lower core temperatures than those in normal-weight individuals. Design: In study 1, nonobese [body mass index (BMI; in kg/m2) temperature–sensing capsules, and we measured core temperatures continuously for 24 h. In study 2, normal-weight (BMI of 18–25) and obese subjects swallowed temperature-sensing capsules to measure core temperatures continuously for ≥48 h and kept activity logs. We constructed daily, 24-h core temperature profiles for analysis. Results: Mean (±SE) daily core body temperature did not differ significantly between the 35 nonobese and 46 obese subjects (36.92 ± 0.03°C compared with 36.89 ± 0.03°C; P = 0.44). Core temperature 24-h profiles did not differ significantly between 11 normal-weight and 19 obese subjects (P = 0.274). Women had a mean core body temperature ≈0.23°C greater than that of men (36.99 ± 0.03°C compared with 36.76 ± 0.03°C; P body temperature. It may be necessary to study individuals with function-altering mutations in core temperature–regulating genes to determine whether differences in the core body temperature set point affect the regulation of human body weight. These trials were registered at clinicaltrials.gov as NCT00428987 and NCT00266500. PMID:21367952

  10. Core stability training on lower limb balance strength.

    Science.gov (United States)

    Dello Iacono, Antonio; Padulo, Johnny; Ayalon, Moshe

    2016-01-01

    This study aimed to assess the effects of core stability training on lower limbs' muscular asymmetries and imbalances in team sport. Twenty footballers were divided into two groups, either core stability or control group. Before each daily practice, core stability group (n = 10) performed a core stability training programme, while control group (n = 10) did a standard warm-up. The effects of the core stability training programme were assessed by performing isokinetic tests and single-leg countermovement jumps. Significant improvement was found for knee extensors peak torque at 3.14 rad · s(-1) (14%; P core stability group. The jump tests showed a significant reduction in the strength asymmetries in core stability group (-71.4%; P = 0.02) while a concurrent increase was seen in the control group (33.3%; P core exercises for optimal lower limbs strength balance development in young soccer players.

  11. Seemingly divergent sea surface temperature proxy records in the central Mediterranean during the last deglaciation

    Directory of Open Access Journals (Sweden)

    M.-A. Sicre

    2013-06-01

    Full Text Available Sea surface temperatures (SSTs were reconstructed over the last 25 000 yr using alkenone paleothermometry and planktonic foraminifera assemblages from two cores of the central Mediterranean Sea: the MD04-2797 core (Siculo–Tunisian channel and the MD90-917 core (South Adriatic Sea. Comparison of the centennial scale structure of the two temperature signals during the last deglaciation period reveals significant differences in timing and amplitude. We suggest that seasonal changes likely account for seemingly proxy record divergences during abrupt transitions from glacial to interglacial climates and for the apparent short duration of the Younger Dryas (YD depicted by the alkenone time series, a feature that has already been stressed in earlier studies on the Mediterranean deglaciation.

  12. 13CO Cores in Taurus Molecular Cloud

    CERN Document Server

    Qian, Lei; Goldsmith, Paul

    2012-01-01

    Young stars form in molecular cores, which are dense condensations within molecular clouds. We have searched for $^{13}$CO $J=1\\to 0$ cores in the Taurus molecular cloud and studied their properties. Our data set has a spatial dynamic range (the ratio of linear map size to the pixel size) of about 1000 and spectrally resolved velocity information. We use empirical fit to the CO and CO$_2$ ice to correct the depletion. The core mass function (CMF) can be fitted better with a log-normal function than with a power law function. We also extract cores and calculate the CMF based on the integrated intensity of $^{13}$CO and the extinction from 2MASS. We demonstrate that there exists core blending, i.e. combined structures that are incoherent in velocity but continuous in column density. The resulting core samples based on 2D and 3D data thus differ significantly from each other. In particular, the cores derived from 2MASS extinction can be fitted with a power-law function, but not a log-normal function. The core ve...

  13. Entrapment of carbon dioxide with chitosan-based core-shell particles containing changeable cores.

    Science.gov (United States)

    Dong, Yanrui; Fu, Yinghao; Lin, Xia; Xiao, Congming

    2016-08-01

    Water-soluble chitosan-based core-shell particles that contained changeable cores were successfully applied to anchor carbon dioxide. The entrapment capacity of the particles for carbon dioxide (EC) depended on the cores. It was found that EC of the particles contained aqueous cores was higher than that of the beads with water-soluble chitosan gel cores, which was confirmed with thermogravimetric analysis. In addition, calcium ions and sodium hydroxide were introduced within the particles to examine their effect on the entrapment. EC of the particles was enhanced with sodium hydroxide when the cores were WSC gel. The incorporation of calcium ions was helpful for stabilizing carbon dioxide through the formation of calcium carbonate, which was verified with Fourier transform infrared spectra and scanning electron microscopy/energy-dispersive spectrometry. This phenomenon meant the role of calcium ions for fixating carbon dioxide was significant.

  14. Biospecimen Core Resource - TCGA

    Science.gov (United States)

    The Cancer Genome Atlas (TCGA) Biospecimen Core Resource centralized laboratory reviews and processes blood and tissue samples and their associated data using optimized standard operating procedures for the entire TCGA Research Network.

  15. NICHD Zebrafish Core

    Data.gov (United States)

    Federal Laboratory Consortium — The core[HTML_REMOVED]s goal is to help researchers of any expertise perform zebrafish experiments aimed at illuminating basic biology and human disease mechanisms,...

  16. iPSC Core

    Data.gov (United States)

    Federal Laboratory Consortium — The induced Pluripotent Stem Cells (iPSC) Core was created in 2011 to accelerate stem cell research in the NHLBI by providing investigators consultation, technical...

  17. Reference: -300CORE [PLACE

    Lifescience Database Archive (English)

    Full Text Available -300CORE Forde BG, Heyworth A, Pywell J, Kreis M Nucleotide sequence of a B1 hordein gene and the identifica...tion of possible upstream regulatory elements in endosperm storage protein genes fr

  18. INTEGRAL core programme

    Science.gov (United States)

    Gehrels, N.; Schoenfelder, V.; Ubertini, P.; Winkler, C.

    1997-01-01

    The International Gamma Ray Astrophysics Laboratory (INTEGRAL) mission is described with emphasis on the INTEGRAL core program. The progress made in the planning activities for