Science.gov

Sample records for age spectrum dating

  1. Plutonium age dating reloaded

    NASA Astrophysics Data System (ADS)

    Sturm, Monika; Richter, Stephan; Aregbe, Yetunde; Wellum, Roger; Mayer, Klaus; Prohaska, Thomas

    2014-05-01

    Although the age determination of plutonium is and has been a pillar of nuclear forensic investigations for many years, additional research in the field of plutonium age dating is still needed and leads to new insights as the present work shows: Plutonium is commonly dated with the help of the 241Pu/241Am chronometer using gamma spectrometry; in fewer cases the 240Pu/236U chronometer has been used. The age dating results of the 239Pu/235U chronometer and the 238Pu/234U chronometer are scarcely applied in addition to the 240Pu/236U chronometer, although their results can be obtained simultaneously from the same mass spectrometric experiments as the age dating result of latter. The reliability of the result can be tested when the results of different chronometers are compared. The 242Pu/238U chronometer is normally not evaluated at all due to its sensitivity to contamination with natural uranium. This apparent 'weakness' that renders the age dating results of the 242Pu/238U chronometer almost useless for nuclear forensic investigations, however turns out to be an advantage looked at from another perspective: the 242Pu/238U chronometer can be utilized as an indicator for uranium contamination of plutonium samples and even help to identify the nature of this contamination. To illustrate this the age dating results of all four Pu/U clocks mentioned above are discussed for one plutonium sample (NBS 946) that shows no signs of uranium contamination and for three additional plutonium samples. In case the 242Pu/238U chronometer results in an older 'age' than the other Pu/U chronometers, contamination with either a small amount of enriched or with natural or depleted uranium is for example possible. If the age dating result of the 239Pu/235U chronometer is also influenced the nature of the contamination can be identified; enriched uranium is in this latter case a likely cause for the missmatch of the age dating results of the Pu/U chronometers.

  2. Thermochronology of economic mineral deposits: dating the stages of mineralization at Panasqueira, Portugal, by high-precision 40Ar/ 39Ar age spectrum techniques on muscovite

    USGS Publications Warehouse

    Snee, L.W.; Sutter, J.F.; Kelly, W.C.

    1988-01-01

    This study is an example of a new and powerful application of 40Ar/39Ar age spectrum dating of muscovite. It is now possible to establish time constraints necessary for solving some of the long-standing problems in economic geology. Beyond this, the unique geologic situation of Panasqueira has allowed us to quantify the thermal characteristics of muscovite. Published fluid inclusion data have been used to estimate a muscovite argon closure temperature of ~325??C during rapid cooling or short reheating and a temperature of ~270??C during slow cooling or extended reheating. Argon-loss patterns displayed by all dated muscovites resulted from reheating after original closure; the mechanism for this argon loss appears to have been argon transport by volume diffusion. Thus, 40Ar/39Ar age spectrum dating of muscovite can be used to evaluate thermal conditions controlling argon diffusion as well as age, duration, and number of episodes of mineralization. -from Authors

  3. Computational Age Dating of Special Nuclear Materials

    SciTech Connect

    None, None

    2012-06-30

    This slide-show presented an overview of the Constrained Progressive Reversal (CPR) method for computing decays, age dating, and spoof detecting. The CPR method is: Capable of temporal profiling a SNM sample; Precise (compared with known decay code, such a ORIGEN); Easy (for computer implementation and analysis). We have illustrated with real SNM data using CPR for age dating and spoof detection. If SNM is pure, may use CPR to derive its age. If SNM is mixed, CPR will indicate that it is mixed or spoofed.

  4. 27 CFR 19.410 - Age and fill date.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Age and fill date. 19.410... Spirits from Customs Custody § 19.410 Age and fill date. For purposes of this part, the age and fill date for spirits imported or brought into the United States will be: (a) The claimed age, as shown on...

  5. 27 CFR 19.410 - Age and fill date.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Age and fill date. 19.410... Spirits from Customs Custody § 19.410 Age and fill date. For purposes of this part, the age and fill date for spirits imported or brought into the United States will be: (a) The claimed age, as shown on...

  6. 27 CFR 19.410 - Age and fill date.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Age and fill date. 19.410... Spirits from Customs Custody § 19.410 Age and fill date. For purposes of this part, the age and fill date for spirits imported or brought into the United States will be: (a) The claimed age, as shown on...

  7. 27 CFR 19.410 - Age and fill date.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Age and fill date. 19.410... Spirits from Customs Custody § 19.410 Age and fill date. For purposes of this part, the age and fill date for spirits imported or brought into the United States will be: (a) The claimed age, as shown on...

  8. 27 CFR 19.482 - Age and fill date.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Age and fill date. 19.482... OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Spirits from Customs Custody § 19.482 Age and fill date. For the purpose of this part, the age and fill date for spirits that are imported or brought...

  9. Age-dating of rockslides: Methods and limitations

    NASA Astrophysics Data System (ADS)

    Ostermann, M.; Sanders, D.; Prager, C.

    2009-04-01

    Age-dating of deposits of catastrophic rockslides is prerequisite to unravel the potential relation between the frequency of mass-wasting events with climatic change or earthquakes. In the Alps, about 250 rockslides exceeding 106 m3 in volume are known, but the age as yet is determined only for a comparatively small number of events. For age determination of rockslide events, different methods are available (e. g. Lang et al., 1999). Radiocarbon Dating In the past few decades, rockslide deposits commonly were proxy-dated by 14C age determination of organic remnants preserved (a) in glacial, fluvio-glacial sediments overridden by the rockslide, (b) within the rockslide mass, or (c) in rockslide-dammed backwater deposits or lakes situated atop the rockslide mass. In each case, the 14C age provides a different constraint on the age of the rockslide event: in case (a), the 14C age represents a maximum age of the event; in case (b), which is quite rare, the 14C age is generally considered as a good proxy of the event age; in case (c) the 14C age represents a minimum age for the rockslide event. Unfortunately, radiocarbon dating often cannot be applied because of absence of suited deposits or exposures thereof, lack of organic remnants or of remnants suited for age-dating, and/or because determined 14C ages are substantially biased. Optically Stimulated Luminescence (OSL) Proxy-dating of rockslide events by OSL can be applied to silt- to sand-sized quartzose sediments present (a) directly below, (b) within, or (c) above/laterally aside a rockslide mass. For each case (a) to (c), the determined ages are subject to the same constraints as outlined for radiocarbon dating. Unfortunately, situations allowing for application of OSL to rockslide event dating are comparatively rare, and the resulting ages tend to have a wide error range. Surface Exposure Dating with cosmogenic radionuclides Surface exposure ages can be determined for rock samples taken from the sliding planes at

  10. Luminescence dating of Middle Stone Age deposits at Die Kelders.

    PubMed

    Feathers, J K; Bush, D A

    2000-01-01

    Luminescence dating of sediments has not been used extensively for dating Middle Stone Age deposits in South Africa, despite its potential for contributing to a poorly dated record. Such deposits at Die Kelders cave, on the southern South African coast, consist of narrow bands of occupation debris separated by thicker layers of aeolian sands containing much less evidence of occupation. Homogeneous, aeolian sediments are usually considered ideal for luminescence dating. Here we report luminescence analyses of five samples from these sands that demonstrate sufficient bleaching prior to burial to validate dating and that yield ages of about 60-70 ka, in agreement with other evidence from sedimentology, archaeology and electron spin resonance. Lack of significant differences in the ages suggests the deposits accumulated fairly rapidly during the early part of the Last Glaciation.

  11. Age Dating of Mixed SNM--Preliminary Investigations

    SciTech Connect

    Yuan, D., Guss, P. P., Yfantis, E., Klingensmith, A., Emer, D.

    2011-12-01

    Recently we investigated the nuclear forensics problem of age determination for mixed special nuclear material (SNM). Through limited computational mixing experiments and interactive age analysis, it was observed that age dating results are generally affected by the mixing of samples with different assays or even by small radioactive material contamination. The mixing and contamination can be detected through interactive age analysis, a function provided by the Decay Interaction, Visualization and Analysis (DIVA) software developed by NSTec. It is observed that for mixed SNM with two components, the age estimators typically fall into two distinct clusters on the time axis. This suggests that averaging or other simple statistical methods may not always be suitable for age dating SNM mixtures. Instead, an interactive age analysis would be more suitable for age determination of material components of such SNM mixtures. This work was supported by the National Center for Nuclear Security (NCNS).

  12. Radiocarbon dating of marine material: mollusc versus foraminifera ages

    NASA Astrophysics Data System (ADS)

    Callard, L.; Long, A. J.; Plets, R. M.; Cooper, A.; Belknap, D. F.; Edwards, R.; Jackson, D.; Kelley, J. T.; Long, D.; Milne, G. A.; Monteys, X.; Quinn, R.

    2013-12-01

    A key challenge in reconstructing Quaternary environmental change from marine archives is developing a robust chronology. During the last ~50k a-1, radiocarbon dating is the mainstay for many studies. Often investigators are restricted in the material that is available for dating, with studies relying on AMS dating of either mono-specific or mixed assemblages of foraminifera. In some instances, marine molluscs (broken or whole, articulated or disarticulated) may also be present and can provide an alternative or complementary dating target. Previous radiocarbon dating of paired foraminiferal and marine molluscan samples from the Kattegat (Denmark) revealed significant age offsets between these materials, inferred to reflect greater reworking of foraminifera compared to the marine molluscs (Heier-Nielsen et al., 1995). Here we present the results of a comparable study from the Irish Sea Basin, which forms part of a wider investigation into the evidence for the Late Glacial sea-level minima at offshore sites from around Britain and Ireland. We have collected and AMS 14C-dated twelve paired samples of foraminifera and marine shells. The results shows a systematic age offset with the monospecific foraminifera samples consistently giving older ages than their shell counterparts. This offset increases with sample age, reaching a maximum offset of 3000 years in the oldest sample (~ 13 ka cal a BP). These results are consistent with the observations of Heier-Nielsen et al. (1995), and we hypothesize that foraminifera may be more susceptible to reworking from older deposits because of their lower effective density than the shell samples. However, foraminifera size and shape may also be contributing factors. These findings are potentially significant for studies that develop chronologies based on radiocarbon dating of foraminifera alone, since the resulting dates may over-estimate sample age by several thousand years. We conclude by outlining an experimental design that seeks

  13. Older Adults' Online Dating Profiles and Successful Aging.

    PubMed

    Wada, Mineko; Mortenson, William Bennett; Hurd Clarke, Laura

    2016-12-01

    This study examined how relevant Rowe and Kahn's three criteria of successful aging were to older adults' self-portrayals in online dating profiles: low probability of disease and disability, high functioning, and active life engagement. In this cross-sectional study, 320 online dating profiles of older adults were randomly selected and coded based on the criteria. Logistic regression analyses determined whether age, gender, and race/ethnicity predicted self-presentation. Few profiles were indicative of successful aging due to the low prevalence of the first two criteria; the third criterion, however, was identified in many profiles. Native Americans were significantly less likely than other ethnic groups to highlight the first two criteria. Younger age predicted presenting the first criterion. Women's presentation of the third criterion remained significantly high with age. The findings suggest that the criteria may be unimportant to older adults when seeking partners, or they may reflect the exclusivity of this construct.

  14. Surface dating of dynamic landforms: young boulders on aging moraines.

    PubMed

    Hallet, B; Putkonen, J

    1994-08-12

    The dating of landforms is crucial to understanding the evolution, history, and stability of landscapes. Cosmogenic isotope analysis has recently been used to determine quantitative exposure ages for previously undatable landform surfaces. A pioneering application of this technique to date moraines illustrated its considerable potential but suggested a chronology partially inconsistent with existing geological data. Consideration of the dynamic nature of landforms and of the ever-present processes of erosion, deposition, and weathering leads to a resolution of this inconsistency and, more generally, offers guidance for realistic interpretation of exposure ages.

  15. Reliability of current CFC data for age dating of water

    NASA Astrophysics Data System (ADS)

    Davila, Pablo; Kuells, Christoph

    2010-05-01

    Age dating of water based on dissolved CFCs and Krypton-85 has been applied extensively for many years. CFCs were adopted as an approach for water dating due to the availability of global input functions and because of a straightforward methodology. In the last decade, due to international treaties, CFCs production and atmospheric concentrations of some trace gases (e.g. Krypton-85) are decreasing. The impact of reduced atmospheric trace gas concentrations on precision and uncertainty of age dating are investigated. Methods for the quantification of uncertainties and approaches for data analysis are presented. The uncertainty analysis is based on the application of different residence time distributions (piston-flow, exponential, advection-dispersion models and combined thereof) for trace gas concentrations and trace gas ratios. Different ways forward are presented to solve the problem of age ambiguity and increased uncertainty: the use of trace gas ratios is demonstrated and their potential of separating pre- and post-peak samples; the combined use of CFCs with additional tracers such as SF6 and 3H are discussed. While both SF6 and tritium have technical limitations themselves, such as multi-finality and observed deviations from the input function, benefit can be gained by combining them with other tracers or combined data analysis approaches. The quantification of uncertainties and of the adaptation of stringent data analysis provides a basis for the use and critical evaluation of CFCs as water age dating methods in the future.

  16. Ar/Ar Dating Independent of Monitor Standard Ages

    NASA Astrophysics Data System (ADS)

    Boswell, S.; Hemming, S. R.

    2015-12-01

    Because the reported age of an analyzed sample is dependent on the age of the co-irradiated monitor standard(s), Ar/Ar dating is a relative dating technique. There is disagreement at the 1% scale in the age of commonly used monitor standards, and there is a great need to improve the inter-laboratory calibrations. Additionally, new approaches and insights are needed to meet the challenge of bringing the Ar/Ar chronometer to the highest possible precision and accuracy. In this spirit, we present a conceptual framework for Ar/Ar dating that does not depend on the age of monitor standards, but only on the K content of a solid standard. The concept is demonstrated by introducing a re-expressed irradiation parameter (JK) that depends on the ratio of 39ArK to 40Ar* rather than the 40Ar*/39ArK ratio. JK is equivalent to the traditional irradiation parameter J and is defined as JK = (39Ar/40K) • (λ/λe). The ultimate precision and accuracy of the method will depend on how precisely and accurately the 39Ar and 40K can be estimated, and will require isotope dilution measurements of both from the same aliquot. We are testing the workability of our technique at the 1% level by measuring weighed and irradiated hornblende and biotite monitor standards using GLO-1 glauconite to define a calibration curve for argon signals versus abundance.

  17. Molecular dating, evolutionary rates, and the age of the grasses.

    PubMed

    Christin, Pascal-Antoine; Spriggs, Elizabeth; Osborne, Colin P; Strömberg, Caroline A E; Salamin, Nicolas; Edwards, Erika J

    2014-03-01

    Many questions in evolutionary biology require an estimate of divergence times but, for groups with a sparse fossil record, such estimates rely heavily on molecular dating methods. The accuracy of these methods depends on both an adequate underlying model and the appropriate implementation of fossil evidence as calibration points. We explore the effect of these in Poaceae (grasses), a diverse plant lineage with a very limited fossil record, focusing particularly on dating the early divergences in the group. We show that molecular dating based on a data set of plastid markers is strongly dependent on the model assumptions. In particular, an acceleration of evolutionary rates at the base of Poaceae followed by a deceleration in the descendants strongly biases methods that assume an autocorrelation of rates. This problem can be circumvented by using markers that have lower rate variation, and we show that phylogenetic markers extracted from complete nuclear genomes can be a useful complement to the more commonly used plastid markers. However, estimates of divergence times remain strongly affected by different implementations of fossil calibration points. Analyses calibrated with only macrofossils lead to estimates for the age of core Poaceae ∼51-55 Ma, but the inclusion of microfossil evidence pushes this age to 74-82 Ma and leads to lower estimated evolutionary rates in grasses. These results emphasize the importance of considering markers from multiple genomes and alternative fossil placements when addressing evolutionary issues that depend on ages estimated for important groups.

  18. Geophysical Age Dating of Seamounts using Dense Core Flexure Model

    NASA Astrophysics Data System (ADS)

    Hwang, Gyuha; Kim, Seung-Sep

    2016-04-01

    Lithospheric flexure of oceanic plate is thermo-mechanical response of an elastic plate to the given volcanic construct (e.g., seamounts and ocean islands). If the shape and mass of such volcanic loads are known, the flexural response is governed by the thickness of elastic plate, Te. As the age of oceanic plate increases, the elastic thickness of oceanic lithosphere becomes thicker. Thus, we can relate Te with the age of plate at the time of loading. To estimate the amount of the driving force due to seamounts on elastic plate, one needs to approximate their density structure. The most common choice is uniform density model, which utilizes constant density value for a seamount. This approach simplifies computational processes for gravity prediction and error estimates. However, the uniform density model tends to overestimate the total mass of the seamount and hence produces more positive gravitational contributions from the load. Minimization of gravity misfits using uniform density, therefore, favors thinner Te in order to increase negative contributions from the lithospheric flexure, which can compensate for the excessive positives from the seamount. An alternative approach is dense core model, which approximate the heterogeneity nature of seamount density as three bodies of infill sediment, edifice, and dense core. In this study, we apply the dense core model to the Louisville Seamount Chain for constraining flexural deformation. We compare Te estimates with the loading time of the examined seamounts to redefine empirical geophysical age dating of seamounts.

  19. Tectonic structures on Mercury: kinematics and age dating

    NASA Astrophysics Data System (ADS)

    Giacomini, Lorenza; Massironi, Matteo; Rothery, David; Di Achille, Gaetano; Marchi, Simone; Galluzzi, Valentina; Ferrari, Sabrina; Fassett, Caleb; Cremonese, Gabriele

    2015-04-01

    At a global scale, Mercury is dominated by contractional features manifested as lobate scarps, wrinkle ridges and high-relief ridges. Here, we show that some of these features are associated with strike-slip kinematic indicators, which we identified using flyby and orbital Mercury Dual Imaging System (MDIS) data and digital terrain models. We recognize oblique-shear kinematics along lobate scarps and high-relief ridges by means of (1) map geometries of fault patterns (frontal thrusts bordered by lateral ramps, strike-slip duplexes, restraining bends); (2) structural morphologies indicating lateral shearing (en echelon folding, pop-ups, pull-aparts); and (3) estimates of offsets based on displaced crater rims and differences in elevation between pop-up structures and pull-apart basins and their surroundings. Transpressional faults, documented across a wide range of latitudes, are found associated with reactivated rims of ancient buried basins and, in most cases, linked to frontal thrusts as lateral ramps hundreds of kilometres long. This latter observation suggests stable directions of tectonic transport over wide regions of Mercury's surface. In contrast, global cooling would imply an overall isotropic contraction with limited processes of lateral shearing induced by pre-existent lithospheric heterogeneities. Mantle convection therefore may have played an important role during the early tectonic evolution of Mercury. Estimating absolute model ages for compressional features and comparing it from what it is envisaged with thermal modeling based on cooling alone can be useful in determining if other processes could have been responsible for lobate scarps nucleation. In particular, ages more ancient that the one predicted by the models would imply other kind of tectonic processes ongoing during the early evolution of Mercury . For this reason, we date an extended thrust system, which we term the Blossom Thrust System, located between 80°E and 100°E, and 30°N and 15

  20. Summary of potassium/argon age dating, 1980

    SciTech Connect

    Evans, S.H. Jr.; Brown, F.H.

    1980-11-01

    A significant improvement in efficiency of the K-Ar laboratory was brought about by completion of a second extraction line. Two extractions can now be done routinely each day and the /sup 38/Ar spike ratios of the new table will permit dating of much younger samples than previously. Extensive K-Ar dating of samples from the Mineral Mountains shows intervals of silicic volcanism at 0.5, 0.8 and 7.5 m.y. K-Ar dating of plutonic units does not present a consistent picture, however. Plutonic events 35 to 40 m.y., 29 m.y. and 19 to 21 m.y. ago are suggested but interpretation must be considered preliminary. Joint programs with the US Geological Survey now underway to study the Rb-Sr and U-Pb systematics of the Mineral Mountains pluton should aid in unravelling its history. Dating of basalts from the Cove Creek Domes/Twin Peaks area, Utah, has aided in delineating the timing of basaltic volcanism. This adds to the already extensive data on the chronology of volcanic activity in the area. Dating of samples from the Beowawe Known Geothermal Resources Area, Nevada have confirmed earlier dates indicating major volcanism took place 38 m.y. ago and 17 to 16 m.y. ago.

  1. Age-Sensitive Effect of Adolescent Dating Experience on Delinquency and Substance Use

    ERIC Educational Resources Information Center

    Kim, Ryang Hui

    2013-01-01

    This study uses a developmental perspective and focuses on examining whether the impact of adolescent dating is age-sensitive. Dating at earlier ages is hypothesized to have a stronger effect on adolescent criminal behavior or substance use, but the effect would be weaker as one ages. The data obtained from the National Longitudinal Survey of…

  2. Into the Unknown: Aging with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Perkins, Elizabeth A.; Berkman, Karen A.

    2012-01-01

    Research investigation of older adults with autism spectrum disorders (ASD) noticeably lags behind studies of children and younger adults with ASD. This article reviews the current literature regarding a range of quality of life outcomes of aging adults with ASD. Studies that have addressed life expectancy, comorbid physical and mental health…

  3. Terrestrial Ages of Antarctic Meteorites: Up Date 1999

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.; Caffee, M. W.; Welten, K. C.

    2000-01-01

    We are continuing our ongoing study of cosmogenic nuclides in Antarctic meteorites. In addition to the studies of exposure histories of meteorites, we study terrestrial ages and pairing of Antarctic meteorites and desert meteorites. Terrestrial ages of Antarctic meteorites provide information on meteorite accumulation mechanisms, mean weathering lifetimes, and influx rates. The determination of Cl-36 (half-life=3.01 x 10(exp 5) y) terrestrial ages is one of our long-term on-going projects, however, in many instances neither Cl-36 or C-14 (5,730 y) yields an accurate terrestrial age. Using Ca-41 (1.04 x 10(exp 5) y) for terrestrial age determinations solves this problem by filling the gap in half-life between C-14 and Cl-36 ages. We are now applying the new Ca-41 - Cl-36 terrestrial age method as well as the Cl-36 - Be-10 method to Antarctic meteorites. Our measurements and C-14 terrestrial age determinations by the University of Arizona group are always complementary.

  4. Age constraints for Palaeolithic cave art by U-Th dating of thin carbonate crusts

    NASA Astrophysics Data System (ADS)

    Hoffmann, Dirk; Pike, Alistair; Garcia-Diez, Marcos; Pettitt, Paul; Zilhão, João

    2015-04-01

    U-series dating is an important geochronological tool which is widely applied for instance in speleothem based palaeoclimate research. It has also great potential to provide age constraints for Archaeology, especially for sites or artefacts in cave environments. We present our methods to conduct precise U-Th dating of calcite crusts that formed on top of cave paintings. Recent developments in multi-collector (MC) inductively coupled plasma mass spectrometry (ICPMS) U-series dating greatly improved the precision of this method, and sample sizes needed to obtain reliable results were significantly reduced. Based on these developments the U-series technique can be applied for accurate dating of thin calcite crusts covering cave art at many sites, while taking care not to harm the art underneath. The method provides minimum ages for the covered art and, where possible, also maximum ages by dating the flowstone layer the art is painted on. The U-Th method has been used in a number of recent projects to date calcite precipitates above and occasionally below cave paintings in Spain. Initial results from Cantabria have shown that the earliest dated paintings are older than 41.4 ± 0.6 ka, dating at least to the Early Aurignacian period and present a far longer chronology than that based so far on radiocarbon dating. Here we outline our methodology and the steps we take to demonstrate the reliability of U-Th dates, and present some recent results of our ongoing U-Th dating programme.

  5. Estimation of Stratospheric Age Spectrum from Chemical Tracers

    NASA Technical Reports Server (NTRS)

    Schoeberl, Mark R.; Douglass, Anne R.; Polansky, Brian

    2005-01-01

    We have developed a technique to diagnose the stratospheric age spectrum and estimate the mean age of air using the distributions of at least four constituents with different photochemical lifetimes. We demonstrate that the technique works using a 3D CTM and then apply the technique to UMS CLAES January 1993 observations of CFC11, CFC12, CH4 and N2O. Our results are generally in agreement with mean age of air estimates from the chemical model and from observations of SF6 and CO2; however, the mean age estimates show an intrusion of very young tropical air into the mid-latitude stratosphere. This feature is consistent with mixing of high N20 air out of the tropics during the westerly phase of the QBO.

  6. Dating, Sex, and Substance Use as Correlates of Adolescents' Subjective Experience of Age

    ERIC Educational Resources Information Center

    Arbeau, Kelly J.; Galambos, Nancy L.; Jansson, S. Mikael

    2007-01-01

    This study examined in a random community-based sample of 664 12-19-year-olds, the relation of subjective experience of age (SEA) with chronological age, dating experience, sexual activity, and substance use. The results revealed a positive linear relation between SEA and chronological age: individuals who were chronologically older felt…

  7. Mothers' Reports of Play Dates and Observation of School Playground Behavior of Children Having High-Functioning Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Frankel, Frederick D.; Gorospe, Clarissa M.; Chang, Ya-Chih; Sugar, Catherine A.

    2011-01-01

    Background: Children with high-functioning autism spectrum disorders (ASD) are generally included with typically developing peers at school. They have difficulties interacting with peers on the school playground. Previous literature suggests that having play dates in the home may be related to better peer acceptance at school. Methods: This study…

  8. Age of Sexual Debut and Physical Dating Violence Victimization: Sex Differences among US High School Students

    ERIC Educational Resources Information Center

    Ihongbe, Timothy O.; Cha, Susan; Masho, Saba W.

    2017-01-01

    Background: Research has shown that early age of sexual debut is associated with physical dating violence (PDV), but sex-specific associations are sparse. We estimated the prevalence of PDV victimization in high school students who have initiated sexual intercourse and examined sex-specific association between age of sexual debut and PDV…

  9. The Impact of Enhanced He and CNONa Abundances on Globular Cluster Relative Age-Dating Methods

    NASA Astrophysics Data System (ADS)

    Marín-Franch, Antonio; Cassisi, Santi; Aparicio, Antonio; Pietrinferni, Adriano

    2010-05-01

    The impact that unrecognized differences in the chemical patterns of Galactic globular clusters (GGCs) have on their relative age determinations is studied. The two most widely used relative age-dating methods, horizontal and vertical, together with the more recent relative MS-fitting method, were carefully analyzed on a purely theoretical basis. The BaSTI library was adopted to perform the present analysis. We find that relative ages derived using the horizontal and vertical methods are largely dependent on the initial He content and heavy element distribution. Unrecognized cluster-to-cluster chemical abundance differences can lead to an error in the derived relative ages as large as ~0.5 (or ~6 Gyr if an age of 12.8 Gyr is adopted for normalization) and even larger for some extreme cases. It is shown that the relative MS-fitting method is by far the age-dating technique for which undetected cluster-to-cluster differences in the He abundance have less impact. Present results are used in order to pose constraints on the maximum possible spread in the He and CNONa elements abundances on the basis of the estimates—taken from the literature—of the GGCs relative age dispersion obtained with the various relative age-dating techniques. Finally, it is shown that the age-metallicity relation found for young GGCs by the GC Treasury program is a real age sequence and cannot be produced by variations in the He and/or heavy element distribution.

  10. Round-robin 230Th–234U age dating of bulk uranium for nuclear forensics

    DOE PAGES

    Gaffney, Amy M.; Hubert, Amélie; Kinman, William S.; ...

    2015-07-30

    In an inter-laboratory measurement comparison study, four laboratories determined 230Th–234U model ages of uranium certified reference material NBL U050 using isotope dilution mass spectrometry. The model dates determined by the participating laboratories range from 9 March 1956 to 19 October 1957, and are indistinguishable given the associated measurement uncertainties. As a result, these model ages are concordant with to slightly older than the known production age of NBL U050.

  11. Revisiting gerontology's scrapbook: from Metchnikoff to the Spectrum Model of Aging.

    PubMed

    Martin, Diane J; Gillen, Laura L

    2014-02-01

    The historical roots of gerontology date to a time when old age was characterized as physical and mental decline. Nonetheless, Metchnikoff questioned the inevitability of this decline, believing that quality of life could be improved by broadening our understanding of the science of aging, a multifaceted concept that extends well beyond the biological science interpretation so prevalent in gerontology's history. This article examines foundational gerontological theories in an effort to unravel complex interactions that constitute physiological aging processes, the psychological manifestations of individual adaptation, and the importance of social and spiritual relationships in aging successfully. Evaluating these theories through an interdisciplinary lens will benefit scholars, researchers, and aging services professionals because it offers opportunities to extend gerontological concepts from theory to development of models that can ultimately be applied in common practice to promote successful aging, regardless of one's physical or cognitive health status. To that end, we propose the Spectrum Model of Aging. Utilizing components of game theory, we believe it offers a synergistic approach to improving quality of later life and thus promises to move the field of gerontology beyond disciplinary boundaries.

  12. Luminescence dating and palaeomagnetic age constraint on hominins from Sima de los Huesos, Atapuerca, Spain.

    PubMed

    Arnold, Lee J; Demuro, Martina; Parés, Josep M; Arsuaga, Juan Luis; Aranburu, Arantza; Bermúdez de Castro, José María; Carbonell, Eudald

    2014-02-01

    Establishing a reliable chronology on the extensive hominin remains at Sima de los Huesos is critical for an improved understanding of the complex evolutionary histories and phylogenetic relationships of the European Middle Pleistocene hominin record. In this study, we use a combination of 'extended-range' luminescence dating techniques and palaeomagnetism to provide new age constraint on sedimentary infills that are unambiguously associated with the Sima fossil assemblage. Post-infrared-infrared stimulated luminescence (pIR-IR) dating of K-feldspars and thermally transferred optically stimulated luminescence (TT-OSL) dating of individual quartz grains provide weighted mean ages of 433 ± 15 ka (thousands of years) and 416 ± 19 ka, respectively, for allochthonous sedimentary horizons overlying the hominin-bearing clay breccia. The six replicate luminescence ages obtained for this deposit are reproducible and provide a combined minimum age estimate of 427 ± 12 ka for the underlying hominin fossils. Palaeomagnetic directions for the luminescence dated sediment horizon and underlying fossiliferous clays display exclusively normal polarities. These findings are consistent with the luminescence dating results and confirm that the hominin fossil horizon accumulated during the Brunhes Chron, i.e., within the last 780 ka. The new bracketing age constraint for the Sima hominins is in broad agreement with radiometrically dated Homo heidelbergensis fossil sites, such as Mauer and Arago, and suggests that the split of the H. neanderthalensis and H. sapiens lineages took place during the early Middle Pleistocene. More widespread numerical dating of key Early and Middle Pleistocene fossil sites across Europe is needed to test and refine competing models of hominin evolution. The new luminescence chronologies presented in this study demonstrate the versatility of TT-OSL and pIR-IR techniques and the potential role they could play in helping to refine evolutionary

  13. Thermoluminescence dating of sediments: a re-extension of age range for loess

    SciTech Connect

    Johnson, R.J.; Stipp, J.J.; Wintle, A.G.; Tamers, M.A.

    1985-01-01

    Thermoluminescence (TL) dating of wind blown minerals provides a technique whereby non-carbonaceous sediments could be dated to several hundred thousand years. Two recent reports, however, indicate age underestimates on feldspar in some European loesses older than 50 ka, the effect increasing in severity with age. Suggested causes include decay of luminescence centers, or does dependent sensitivity changes. Data presented in this paper do not support these limitations or explanations. TL provides 3 separate techniques of dating sediments, which, when used together, prove to be efficient internal cross checks for mineralogical anomalies or inconsistencies created by any of the individual methods. In the authors studies each sample was dated by all 3 methods whereas the Europeans analyses employed only the Regeneration technique. This work presents results from loess sections in Mississippi, Illinois and Alaska. These show excellent internal consistency, and consistency with both independent dating methods and stratigraphy, with 2 exceptions. Both exceptions were by the Regen technique giving age underestimates up to 30%. The underestimates were found to be caused by a change in mineral sensitivity resulting from the Regen requirements of strong laboratory light-bleaching followed by irradiations. A simple method to test and correct for this condition is presented. TL thus appears to remain a powerful and increasingly flexible method of sediment dating.

  14. Dating earthquakes with high-precision thorium-230 ages of very young corals

    NASA Technical Reports Server (NTRS)

    Edwards, R. Lawrence; Wasserburg, G. J.; Taylor, F. W.

    1988-01-01

    Three corals from Vanuatu Islands, whose ages were known from counting annual growth bands, were analyzed by Th-230 age analysis to asses the accuracy of the Th-230 method. The comparison of Th-230 ages with the growth-band ages showed that the Th-230 ages were accurate within an error of + or - 3-5 y. Th-230 dates were then determined for two adjacent emerged heads from Santo Island; the dates were the same, indicating that the heads died at the same time, and consistent with the theory that they were killed by coseismic emergence around 1865 AD. The difference between this data and the data of the only major historically documented earthquake that caused an uplift (1973) suggests a seismic recurrence interval of 108 + or - 4 y for Santo. It is suggested that this approach may be extended back in time and to other localities.

  15. Age Dating Fluvial Sediment Storage Reservoirs to Construct Sediment Waiting Time Distributions

    NASA Astrophysics Data System (ADS)

    Skalak, K.; Pizzuto, J. E.; Benthem, A.; Karwan, D. L.; Mahan, S.

    2015-12-01

    Suspended sediment transport is an important geomorphic process that can often control the transport of nutrients and contaminants. The time a particle spends in storage remains a critical knowledge gap in understanding particle trajectories through landscapes. We dated floodplain deposits in South River, VA, using fallout radionuclides (Pb-210, Cs-137), optically stimulated luminescence (OSL), and radiocarbon dating to determine sediment ages and construct sediment waiting time distributions. We have a total of 14 age dates in two eroding banks. We combine these age dates with a well-constrained history of mercury concentrations on suspended sediment in the river from an industrial release. Ages from fallout radionuclides document sedimentation from the early 1900s to the present, and agree with the history of mercury contamination. OSL dates span approximately 200 to 17,000 years old. We performed a standard Weibull analysis of nonexceedance to construct a waiting time distribution of floodplain sediment for the South River. The mean waiting time for floodplain sediment is 2930 years, while the median is approximately 710 years. When the floodplain waiting time distribution is combined with the waiting time distribution for in-channel sediment storage (available from previous studies), the mean waiting time shifts to approximately 680 years, suggesting that quantifying sediment waiting times for both channel and floodplain storage is critical in advancing knowledge of particle trajectories through watersheds.

  16. Age of Zhoukoudian Homo erectus determined with (26)Al/(10)Be burial dating.

    PubMed

    Shen, Guanjun; Gao, Xing; Gao, Bin; Granger, Darryl E

    2009-03-12

    The age of Zhoukoudian Homo erectus, commonly known as 'Peking Man', has long been pursued, but has remained problematic owing to the lack of suitable dating methods. Here we report cosmogenic (26)Al/(10)Be burial dating of quartz sediments and artefacts from the lower strata of Locality 1 in the southwestern suburb of Beijing, China, where early representatives of Zhoukoudian Homo erectus were discovered. This study marks the first radioisotopic dating of any early hominin site in China beyond the range of mass spectrometric U-series dating. The weighted mean of six meaningful age measurements, 0.77 +/- 0.08 million years (Myr, mean +/- s.e.m.), provides the best age estimate for lower cultural layers 7-10. Together with previously reported U-series dating of speleothem calcite and palaeomagnetic stratigraphy, as well as sedimentological considerations, these layers may be further correlated to S6-S7 in Chinese loess stratigraphy or marine isotope stages (MIS) 17-19, in the range of approximately 0.68 to 0.78 Myr ago. These ages are substantially older than previously supposed and may imply early hominin's presence at the site in northern China through a relatively mild glacial period corresponding to MIS 18.

  17. Rewriting the Central European Early Bronze Age Chronology: Evidence from Large-Scale Radiocarbon Dating

    PubMed Central

    Knipper, Corina; Friedrich, Ronny; Kromer, Bernd; Lindauer, Susanne; Radosavljević, Jelena; Wittenborn, Fabian; Krause, Johannes

    2015-01-01

    The transition from the Neolithic to the Early Bronze Age in Central Europe has often been considered as a supra-regional uniform process, which led to the growing mastery of the new bronze technology. Since the 1920s, archaeologists have divided the Early Bronze Age into two chronological phases (Bronze A1 and A2), which were also seen as stages of technical progress. On the basis of the early radiocarbon dates from the cemetery of Singen, southern Germany, the beginning of the Early Bronze Age in Central Europe was originally dated around 2300/2200 BC and the transition to more complex casting techniques (i.e., Bronze A2) around 2000 BC. On the basis of 140 newly radiocarbon dated human remains from Final Neolithic, Early and Middle Bronze Age cemeteries south of Augsburg (Bavaria) and a re-dating of ten graves from the cemetery of Singen, we propose a significantly different dating range, which forces us to re-think the traditional relative and absolute chronologies as well as the narrative of technical development. We are now able to date the beginning of the Early Bronze Age to around 2150 BC and its end to around 1700 BC. Moreover, there is no transition between Bronze (Bz) A1 and Bronze (Bz) A2, but a complete overlap between the type objects of the two phases from 1900–1700 BC. We thus present a revised chronology of the assumed diagnostic type objects of the Early Bronze Age and recommend a radiocarbon-based view on the development of the material culture. Finally, we propose that the traditional phases Bz A1 and Bz A2 do not represent a chronological sequence, but regionally different social phenomena connected to the willingness of local actors to appropriate the new bronze technology. PMID:26488413

  18. Rewriting the Central European Early Bronze Age Chronology: Evidence from Large-Scale Radiocarbon Dating.

    PubMed

    Stockhammer, Philipp W; Massy, Ken; Knipper, Corina; Friedrich, Ronny; Kromer, Bernd; Lindauer, Susanne; Radosavljević, Jelena; Wittenborn, Fabian; Krause, Johannes

    2015-01-01

    The transition from the Neolithic to the Early Bronze Age in Central Europe has often been considered as a supra-regional uniform process, which led to the growing mastery of the new bronze technology. Since the 1920s, archaeologists have divided the Early Bronze Age into two chronological phases (Bronze A1 and A2), which were also seen as stages of technical progress. On the basis of the early radiocarbon dates from the cemetery of Singen, southern Germany, the beginning of the Early Bronze Age in Central Europe was originally dated around 2300/2200 BC and the transition to more complex casting techniques (i.e., Bronze A2) around 2000 BC. On the basis of 140 newly radiocarbon dated human remains from Final Neolithic, Early and Middle Bronze Age cemeteries south of Augsburg (Bavaria) and a re-dating of ten graves from the cemetery of Singen, we propose a significantly different dating range, which forces us to re-think the traditional relative and absolute chronologies as well as the narrative of technical development. We are now able to date the beginning of the Early Bronze Age to around 2150 BC and its end to around 1700 BC. Moreover, there is no transition between Bronze (Bz) A1 and Bronze (Bz) A2, but a complete overlap between the type objects of the two phases from 1900-1700 BC. We thus present a revised chronology of the assumed diagnostic type objects of the Early Bronze Age and recommend a radiocarbon-based view on the development of the material culture. Finally, we propose that the traditional phases Bz A1 and Bz A2 do not represent a chronological sequence, but regionally different social phenomena connected to the willingness of local actors to appropriate the new bronze technology.

  19. Improving age constraints on Patagonian glaciations using a new luminescence dating method for feldspars

    NASA Astrophysics Data System (ADS)

    Smedley, R. K.; Glasser, N. F.; Duller, G. A.

    2013-12-01

    Multiple moraine ridges are preserved in the Lago Buenos Aires and Lago Pueyrrédon valleys, east of the Northern Patagonian Icefield and offer a unique perspective on understanding past environmental change in the mid-latitudes of the Southern Hemisphere. Previous age constraints provided for the moraine ridges relies on cosmogenic isotope dating and constraining radiocarbon and 40Ar/36Ar ages. Providing age constraints using luminescence dating of the glaciofluvial landforms associated with the moraine ridges offers great potential to contribute towards improving the accuracy and precision of age constraints in such challenging glacial settings. This is the first study to use a new luminescence dating method recently developed for feldspars (Thomsen et al. 2008) to constrain the ages of moraine deposition. A range of sediments were sampled from the outwash plains and glaciofluvial channels that are associated with moraine deposition in the Lago Buenos Aires and Lago Pueyrrédon valleys. Elevation measurements and the geomorphological context of the outwash plains and glaciofluvial channels are used to relate the sampled material to the associated moraine ridges, and therefore constrain the ages of moraine deposition in the valleys. Moraine ridges dated using cosmogenic isotope dating to the Last Glacial Maximum are the main focus of this study, but the overall aim is to provide a new dating technique that can be used to understand the temporal and spatial extent of terrestrial environmental change during past glaciations of the mid-latitudes in the Southern Hemisphere. Thomsen, K.J., Murray, A.S., Jain, M. and Bøtter-Jensen, L. 2008. Laboratory fading rates of various luminescence signals from feldspar-rich sediment extracts. Radiation Measurements 43, 1474 - 1486.

  20. Minimally verbal school-aged children with autism spectrum disorder: the neglected end of the spectrum.

    PubMed

    Tager-Flusberg, Helen; Kasari, Connie

    2013-12-01

    It is currently estimated that about 30% of children with autism spectrum disorder remain minimally verbal, even after receiving years of interventions and a range of educational opportunities. Very little is known about the individuals at this end of the autism spectrum, in part because this is a highly variable population with no single set of defining characteristics or patterns of skills or deficits, and in part because it is extremely challenging to provide reliable or valid assessments of their developmental functioning. In this paper, we summarize current knowledge based on research including minimally verbal children. We review promising new novel methods for assessing the verbal and nonverbal abilities of minimally verbal school-aged children, including eye-tracking and brain-imaging methods that do not require overt responses. We then review what is known about interventions that may be effective in improving language and communication skills, including discussion of both nonaugmentative and augmentative methods. In the final section of the paper, we discuss the gaps in the literature and needs for future research.

  1. Archaeomagnetic Dating of Bronze Age Pottery in Syria: New Intensity Data for 2300 to 1000 BCE

    NASA Astrophysics Data System (ADS)

    Stillinger, M. D.; Feinberg, J. M.; Frahm, E.

    2013-12-01

    In order to construct meaningful site chronologies, Near Eastern archaeologists have traditionally relied on relative dating techniques, such as ceramic seriation and textual/glyptic evidence. The introduction of radiocarbon dating provided archaeologists with an absolute dating tool to address age discrepancies. However, many sites do not contain sufficient or suitable materials for radiocarbon analysis, requiring the need for an alternative absolute dating tool. Archaeomagnetic dating provides such an alternative. Excavations at Tell Mozan (Bronze-Age Urkesh) in northeastern Syria have revealed evidence for nearly 5000 years of occupation in strata containing a variety of diagnostic ceramic artifacts, which form the basis for a well-established relative site chronology. In order to test the agreement between seriation ages and paleomagnetic-derived ages, archaeointensity experiments were conducted on pottery specimens from six well-stratified occupational layers spanning more than a thousand years of the site's primary occupation. Archaeointensity was determined using the IZZI paleointensity protocol of Tauxe and Staudigel (2004), and all estimates were corrected for remanence anisotropy and cooling rate effects, resulting in an 88% success rate (n = 51). The magnetic mineral assemblage of each sample was also characterized using a comprehensive suite of rock magnetic techniques. Final results were compared with previous archaeointensity studies in the region, and 70% of the magnetically-derived ages agree with the archaeologically-derived dates within a 1σ confidence interval, while 76% agreed within 2σ. Artifacts showing disagreement with the seriation chronology are most likely objects in use long after their original firing or the result of contamination of strata from the re-use of previous occupational materials in construction. One specimen appears to confirm the presence of a geomagnetic spike around 1000 BCE previously identified in Syria, Israel

  2. Aging with autism spectrum disorder: an emerging public health problem.

    PubMed

    Hategan, Ana; Bourgeois, James A; Goldberg, Jeremy

    2016-09-27

    From 1943, when Leo Kanner originally described autism, and to the first objective criteria for "infantile autism" in DSM-III and the inclusion of Asperger's disorder in DSM-IV, the subsequent classification scheme for autistic disorders has led to a substantial change with the 2013 issuance of the DSM-5 by including subcategories into one umbrella diagnosis of autism spectrum disorder (ASD) (Baker, 2013). ASD is a lifelong neurodevelopmental disorder, characterized by social and communication impairments and restricted, stereotypical patterns of behavior (Baker, 2013). It is currently expected that most, or all of the actual cases of ASD, are identified in a timely way (i.e. in early childhood). However, there are many undiagnosed older adults who may have met the current diagnostic criteria for ASD as children, but never received such a diagnosis due to the fact it had yet to be established. In addition, some patients with relatively less impairing phenotypes may escape formal diagnosis in childhood, only to later be diagnosed in adulthood. Nevertheless, the first generation of diagnosed patients with ASD is now in old age. Many such ASD patients have needed family and institutional support for their lives subsequent to childhood diagnosis. Due to aging and death of their parents and other supportive figures leading to a loss of social structures, there is no better time than now for the medical community to act.

  3. Cation-ratio dating: A new rock varnish age-determination technique

    NASA Astrophysics Data System (ADS)

    Dorn, Ronald I.

    1983-07-01

    Rock varnish coats many surfaces of geomorphic and archaeologic interest in arid lands. All varnish dating techniques are limited by the time lag between the exposure of a surface to subaerial processes and the onset of varnishing. They are valid only where manganese is not remobilized after deposition, for example, in most arid environments. The premise of a new age-determination method, cation-ratio dating, is that the ratio of the more mobile cations (e.g., K and Ca) to titanium in varnish decreases with time. Although there are many inherent assumptions and potential limitations, cation-ratio dating has been verified on relative age-sequences from a Death Valley debris cone, Negev Desert talus flatirons, and prehistoric lake levels at Searles Lake in California. Varnish cation ratios have been calibrated to independently dated surfaces in the Coso volcanic field and vicinity in California. Tentative absolute dates have been assigned to geomorphic surfaces in the Coso area. Cation ratios have been used to distinguish relative ages of archaeologic artifacts in southwestern North America and to demonstrate that varnish at the South Stoddard locality, Mojave Desert, did not form in 25 yr.

  4. Thermoluminescence dating of archaeological artefacts from the Middle Neolithic, Bronze Age and the Roman Empire period.

    PubMed

    Berger, T; Hajek, M; Primerano, W; Vana, N

    2002-01-01

    Thermoluminescence (TL) dating was applied for artefacts found near the small village of Michelstetten, Lower Austria. Settlements in this region can be traced hack a long time and, according to archaeologists, the discovered artefacts may be as old as 6000 years. A modified sample preparation technique based on the fine-grain method was developed. This technique results in a higher reproducibility and reduces the overall preparation time. For some artefacts the new information of the TL dating leads to an unforeseen re-interpretation of the archaeological age. Furthermore, an iron furnace from the period of the Roman Empire could be dated. For the first time, it was possible to estimate correctly the point of time of the burn-down of an ancient wooden house via an analysis of the house's clay plaster. The fire took place in the sixth century; this was confirmed by dating ceramic artefacts.

  5. A revised burial dose estimation procedure for optical dating of youngand modern-age sediments

    USGS Publications Warehouse

    Arnold, L.J.; Roberts, R.G.; Galbraith, R.F.; DeLong, S.B.

    2009-01-01

    The presence of genuinely zero-age or near-zero-age grains in modern-age and very young samples poses a problem for many existing burial dose estimation procedures used in optical (optically stimulated luminescence, OSL) dating. This difficulty currently necessitates consideration of relatively simplistic and statistically inferior age models. In this study, we investigate the potential for using modified versions of the statistical age models of Galbraith et??al. [Galbraith, R.F., Roberts, R.G., Laslett, G.M., Yoshida, H., Olley, J.M., 1999. Optical dating of single and multiple grains of quartz from Jinmium rock shelter, northern Australia: Part I, experimental design and statistical models. Archaeometry 41, 339-364.] to provide reliable equivalent dose (De) estimates for young and modern-age samples that display negative, zero or near-zero De estimates. For this purpose, we have revised the original versions of the central and minimum age models, which are based on log-transformed De values, so that they can be applied to un-logged De estimates and their associated absolute standard errors. The suitability of these 'un-logged' age models is tested using a series of known-age fluvial samples deposited within two arroyo systems from the American Southwest. The un-logged age models provide accurate burial doses and final OSL ages for roughly three-quarters of the total number of samples considered in this study. Sensitivity tests reveal that the un-logged versions of the central and minimum age models are capable of producing accurate burial dose estimates for modern-age and very young (<350??yr) fluvial samples that contain (i) more than 20% of well-bleached grains in their De distributions, or (ii) smaller sub-populations of well-bleached grains for which the De values are known with high precision. Our results indicate that the original (log-transformed) versions of the central and minimum age models are still preferable for most routine dating applications

  6. ENHANCED RECOVERY METHODS FOR 85KR AGE-DATING GROUNDWATER: ROYAL WATERSHED, MAINE

    EPA Science Inventory

    Potential widespread use of 85Kr, having a constant input function in the northern hemisphere, for groundwater age-dating would advance watershed investigations. The current input function of tritium is not sufficient to estimate young modern recharge waters. While tri...

  7. Deep-ocean basalts: inert gas content and uncertainties in age dating.

    PubMed

    Noble, C S; Naughton, J J

    1968-10-11

    The radiogenic argon and helium contents of three basalts erupted into the deep ocean from an active volcano (Kilauea) have been measured. Ages calculated from these measurements increase with sample depth up to 22 million years for lavas deduced to be recent. Caution is urged in applying dates from deep-ocean basalts in studies on ocean-floor spreading.

  8. THE IMPACT OF ENHANCED He AND CNONa ABUNDANCES ON GLOBULAR CLUSTER RELATIVE AGE-DATING METHODS

    SciTech Connect

    MarIn-Franch, Antonio; Aparicio, Antonio; Cassisi, Santi; Pietrinferni, Adriano E-mail: antapaj@iac.e E-mail: pietrinferni@oa-teramo.inaf.i

    2010-05-10

    The impact that unrecognized differences in the chemical patterns of Galactic globular clusters (GGCs) have on their relative age determinations is studied. The two most widely used relative age-dating methods, horizontal and vertical, together with the more recent relative MS-fitting method, were carefully analyzed on a purely theoretical basis. The BaSTI library was adopted to perform the present analysis. We find that relative ages derived using the horizontal and vertical methods are largely dependent on the initial He content and heavy element distribution. Unrecognized cluster-to-cluster chemical abundance differences can lead to an error in the derived relative ages as large as {approx}0.5 (or {approx}6 Gyr if an age of 12.8 Gyr is adopted for normalization) and even larger for some extreme cases. It is shown that the relative MS-fitting method is by far the age-dating technique for which undetected cluster-to-cluster differences in the He abundance have less impact. Present results are used in order to pose constraints on the maximum possible spread in the He and CNONa elements abundances on the basis of the estimates-taken from the literature-of the GGCs relative age dispersion obtained with the various relative age-dating techniques. Finally, it is shown that the age-metallicity relation found for young GGCs by the GC Treasury program is a real age sequence and cannot be produced by variations in the He and/or heavy element distribution.

  9. Estimation of submarine mass failure probability from a sequence of deposits with age dates

    USGS Publications Warehouse

    Geist, Eric L.; Chaytor, Jason D.; Parsons, Thomas E.; ten Brink, Uri S.

    2013-01-01

    The empirical probability of submarine mass failure is quantified from a sequence of dated mass-transport deposits. Several different techniques are described to estimate the parameters for a suite of candidate probability models. The techniques, previously developed for analyzing paleoseismic data, include maximum likelihood and Type II (Bayesian) maximum likelihood methods derived from renewal process theory and Monte Carlo methods. The estimated mean return time from these methods, unlike estimates from a simple arithmetic mean of the center age dates and standard likelihood methods, includes the effects of age-dating uncertainty and of open time intervals before the first and after the last event. The likelihood techniques are evaluated using Akaike’s Information Criterion (AIC) and Akaike’s Bayesian Information Criterion (ABIC) to select the optimal model. The techniques are applied to mass transport deposits recorded in two Integrated Ocean Drilling Program (IODP) drill sites located in the Ursa Basin, northern Gulf of Mexico. Dates of the deposits were constrained by regional bio- and magnetostratigraphy from a previous study. Results of the analysis indicate that submarine mass failures in this location occur primarily according to a Poisson process in which failures are independent and return times follow an exponential distribution. However, some of the model results suggest that submarine mass failures may occur quasiperiodically at one of the sites (U1324). The suite of techniques described in this study provides quantitative probability estimates of submarine mass failure occurrence, for any number of deposits and age uncertainty distributions.

  10. Surface exposure dating of Little Ice Age ice cap advances on Disko Island, West Greenland

    NASA Astrophysics Data System (ADS)

    Lane, Timothy; Jomelli, Vincent; Rinterknecht, Vincent; Brunstein, Daniel; Schimmelpfennig, Irene; Swingedouw, Didier; Favier, Vincent; Masson-Delmotte, Valerie

    2015-04-01

    Little Ice Age (LIA: 1200-1920 AD) glacier advances in Greenland often form the most extensive positions of Greenland Ice Sheet (GrIS) ice cap and margins since the Early Holocene. Across Greenland these advances are commonly represented by un-vegetated moraines, usually within 1-5 km of the present ice margin. However, chronological constraints on glacier advances during this period are sparse, meaning that GrIS and ice cap behavior and advance/retreat chronology remains poorly understood during this period. At present the majority of ages are based on historical accounts, ice core data, and radiocarbon ages from proglacial threshold lakes. However, developments in the accuracy and precision of surface exposure methods allow dating of LIA moraine boulders, permitting an opportunity to better understand of ice dynamics during this period. Geomorphological mapping and surface exposure dating (36Cl) were used to interpret moraine deposits from the Lyngmarksbræen on Disko Island, West Greenland. A Positive Degree Day (PDD) model was used to estimate Equilibrium Line Altitude (ELA) and mass balance changes for two distinct paleo-glacial extents. Three moraines (M1, M2, and M3) were mapped in the field, and sampled for 36Cl surface exposure dating. The outermost moraine (M1) was of clearly different morphology to the inner moraines, and present only in small fragments. M2 and M3 were distinct arcuate termino-lateral moraines within 50 m of one another, 1.5 km from the present ice margin. The weighted average of four 36Cl ages from M1 returned an early Holocene age of 8.4 ± 0.6 ka. M2 (four samples) returned an age of 0.57 ± 0.04 ka (1441 AD) and M3 (four samples) returned an age of 0.28 ± 0.02 ka (1732 AD). These surface exposure ages represent the first robustly dated Greenlandic ice cap moraine sequence from the LIA. The two periods of ice cap advance and marginal stabilisation are similar to recorded periods of LIA GrIS advance in west Greenland, constrained

  11. What is the true age uncertainty of radiocarbon dated Holocene records?

    NASA Astrophysics Data System (ADS)

    Ho, Sze Ling; Groeneveld, Jeroen; Refeld, Kira; Mollenhauer, Gesine; De Pol-Holz, Ricardo; Nürnberg, Dirk; Laepple, Thomas

    2016-04-01

    Radiocarbon-based age-depth models are the backbone of the chronology of Holocene sediment records. The uncertainty of such age-depth models is often estimated from the uncertainty of the calibrated radiocarbon samples. A necessary assumption hereby is that the age of the samples is representative for the proxies in the same sediment layer they originate from. Here we generate radiocarbon and multiple temperature proxy data in three Holocene sediment cores from the same multi-corer employed in the Southwest Pacific. Surprisingly, whilst radiocarbon ages at the same sediment depth strongly differ between the tubes, multiple independent proxy time-series measured in each of the sediment cores suggest stratified sediments at the site. This is based on the finding that proxy time-series correlate significantly better between sediment cores when analyzed over depth, rather than against core-specific age-depth models based on the radiocarbon dates. If our site is not a pathological special case - an argument which we have no evidence for - our finding has important implications for age-depth modeling and the interpretations of paleoclimate time-series. It suggests that the true age uncertainty of a sediment layer can be much higher than the uncertainty obtained from the radiocarbon dates. An alternative but less likely hypothesis is that the proxy values are modified post-deposition in the sediments, resulting in more consistent stratification than the original climate signal time-series. Our study demonstrates the usefulness of replication of the proxy time series and radiocarbon dates in the quest for chronologic precision and proxy reliability, which are crucial for a more quantitative understanding of Holocene climate evolution.

  12. Geoarchaeological dating of Holocene-age, earthquake-induced paleoliquefaction features in southwestern Indiana

    SciTech Connect

    Munson, C.A. ); Munson, P.J.; Garniewicz, R.C. . Dept. of Anthropology)

    1992-01-01

    Although archaeological geology generally involves the application of geological methods to archaeological research questions, recent research on earthquake-induced paleoliquefaction in Indiana provides an example off archeological methods applied to geological questions. Surveys in 1990-1992 have documented numerous paleoliquefaction features in Holocene-age alluvial sediments in the Wabash Valley region of southwestern Indiana that resulted from strong-earthquake shaking. A combination of archaeological and geological dating is critical to the study of prehistoric earthquakes in this region, where evidence of surface faulting is absent. Both direct dating and cross-dating are being used to develop a chronology for stratigraphic sequences within the alluvial facies of the Martinsville Formation. Temporally diagnostic artifacts and archaeological features such as hearths add significantly to the traditional array of datable samples from strata that underlie, overlie, or are penecontemporary with the sand- or gravel-filled dikes and buried sand blows that resulted from liquefaction. Dating of stratigraphic sequences and paleoliquefaction features is essential for estimating the recurrence intervals of prehistoric earthquakes and the geographic extents, epicentral locations, and magnitudes of specific events. Dating of stratigraphic sequences is also relevant to reconstructions of the prehistoric landscapes that were used for human settlement throughout the last 11,000 years.

  13. Age of Zinjanthropus: The potassium-argon dates recently obtained from Olduvai Gorge, Tanganyika, raise several questions.

    PubMed

    Straus, W L; Hunt, C B

    1962-04-27

    Because some of the Olduvai Gorge dates are inconsistent, some must be inaccurate; they may all be. Until further tests determine which materials give dependable dates, we do not know which dates are accurate. Until this is learned, the indicated ages must be taken cum grano salis.

  14. Theoretical constraints on the precision and age range of rehydroxylation dating

    PubMed Central

    Hare, V. J.

    2015-01-01

    Accurate and precise dating methods are of central importance to archaeology, palaeontology and earth science. This paper investigates the expected precision and age range of rehydroxylation dating, a recently proposed technique for fired clays. An expression for combined measurement uncertainty is presented, which takes into account all significant sources of experimental uncertainty. Numerical simulations are performed for comparison. Combined measurement uncertainties of approximately 5% with respect to the age of the ceramic should be possible given well-designed experiments. In this case, the most significant contribution to combined measurement uncertainty is from effective lifetime temperature. In addition, it is shown that precision should be acceptable for recently fired material (less than 1 year). Mismatch of balance resolution to sample mass results in large variation in combined relative uncertainties, which vary by four orders of magnitude (approx. 1–1160%) across recent experimental studies, rendering some recently reported dates meaningless. It is recommended that this ratio be less than 10−6 for a combined relative uncertainty of less than 1%. The age limits of the technique are set by the value of the rate constant and individual sample mineralogy. This theoretical framework should help future interlaboratory comparison as well as optimizing instrument design. PMID:26064631

  15. Theoretical constraints on the precision and age range of rehydroxylation dating.

    PubMed

    Hare, V J

    2015-04-01

    Accurate and precise dating methods are of central importance to archaeology, palaeontology and earth science. This paper investigates the expected precision and age range of rehydroxylation dating, a recently proposed technique for fired clays. An expression for combined measurement uncertainty is presented, which takes into account all significant sources of experimental uncertainty. Numerical simulations are performed for comparison. Combined measurement uncertainties of approximately 5% with respect to the age of the ceramic should be possible given well-designed experiments. In this case, the most significant contribution to combined measurement uncertainty is from effective lifetime temperature. In addition, it is shown that precision should be acceptable for recently fired material (less than 1 year). Mismatch of balance resolution to sample mass results in large variation in combined relative uncertainties, which vary by four orders of magnitude (approx. 1-1160%) across recent experimental studies, rendering some recently reported dates meaningless. It is recommended that this ratio be less than 10(-6) for a combined relative uncertainty of less than 1%. The age limits of the technique are set by the value of the rate constant and individual sample mineralogy. This theoretical framework should help future interlaboratory comparison as well as optimizing instrument design.

  16. A practical method of estimating standard error of age in the fission track dating method

    USGS Publications Warehouse

    Johnson, N.M.; McGee, V.E.; Naeser, C.W.

    1979-01-01

    A first-order approximation formula for the propagation of error in the fission track age equation is given by PA = C[P2s+P2i+P2??-2rPsPi] 1 2, where PA, Ps, Pi and P?? are the percentage error of age, of spontaneous track density, of induced track density, and of neutron dose, respectively, and C is a constant. The correlation, r, between spontaneous are induced track densities is a crucial element in the error analysis, acting generally to improve the standard error of age. In addition, the correlation parameter r is instrumental is specifying the level of neutron dose, a controlled variable, which will minimize the standard error of age. The results from the approximation equation agree closely with the results from an independent statistical model for the propagation of errors in the fission-track dating method. ?? 1979.

  17. Relation of Chlorofluorocarbon Ground-Water Age Dates to Water Quality in Aquifers of West Virginia

    USGS Publications Warehouse

    ,; Kurt, J.; Kozar, Mark D.

    2007-01-01

    The average apparent age of ground water in fractured-bedrock aquifers in West Virginia was determined using chlorofluorocarbon (CFC) dating methods. Since the introduction of CFC gases as refrigerants in the late 1930s, atmospheric concentrations have increased until production ceased in the mid-1990s. CFC dating methods are based on production records that date to the early 1940s, and the preservation of atmospheric CFC concentrations in ground water at the time of recharge. As part of the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) and Ambient Ground-Water Monitoring Network (AGN) programs in West Virginia from 1997 to 2005, 80 samples from the Appalachian Plateaus Physiographic Province, 27 samples from the Valley and Ridge Physiographic Province, and 5 samples from the Ohio River alluvial aquifers were collected to estimate ground-water ages in aquifers of West Virginia. Apparent CFC ages of water samples from West Virginia aquifers ranged from 5.8 to 56 years. In the Appalachian Plateaus, topographically driven ground-water flow is evident from apparent ages of water samples from hilltop, hillside, and valley settings (median apparent ages of 12, 14, and 25 years, respectively). Topographic setting was the only factor that was found to be related to apparent ground-water age in the Plateaus at the scale of this study. Similar relations were not found in Valley and Ridge aquifers, indicating that other factors such as bedding or geologic structure may serve larger roles in controlling ground-water flow in that physiographic province. Degradation of CFCs was common in samples collected from methanogenic/anoxic aquifers in the Appalachian Plateaus and suboxic to anoxic aquifers in the Valley and Ridge. CFC contamination was most common in Ohio River alluvial aquifers and carbonate units of the Valley and Ridge, indicating that these highly transmissive surficial aquifers are the most vulnerable to water-quality degradation and may

  18. Assessment of School-Aged Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Paynter, Jessica M.

    2015-01-01

    An increasing number of school children are diagnosed with Autism Spectrum Disorder (ASD). These children may be referred for assessments for a variety of reasons, including to assess for intellectual impairments, eligibility for support, or to monitor progress. Characteristics of ASD, such as social communication difficulties, as well as common…

  19. The evolutionary relationships and age of Homo naledi: An assessment using dated Bayesian phylogenetic methods.

    PubMed

    Dembo, Mana; Radovčić, Davorka; Garvin, Heather M; Laird, Myra F; Schroeder, Lauren; Scott, Jill E; Brophy, Juliet; Ackermann, Rebecca R; Musiba, Chares M; de Ruiter, Darryl J; Mooers, Arne Ø; Collard, Mark

    2016-08-01

    Homo naledi is a recently discovered species of fossil hominin from South Africa. A considerable amount is already known about H. naledi but some important questions remain unanswered. Here we report a study that addressed two of them: "Where does H. naledi fit in the hominin evolutionary tree?" and "How old is it?" We used a large supermatrix of craniodental characters for both early and late hominin species and Bayesian phylogenetic techniques to carry out three analyses. First, we performed a dated Bayesian analysis to generate estimates of the evolutionary relationships of fossil hominins including H. naledi. Then we employed Bayes factor tests to compare the strength of support for hypotheses about the relationships of H. naledi suggested by the best-estimate trees. Lastly, we carried out a resampling analysis to assess the accuracy of the age estimate for H. naledi yielded by the dated Bayesian analysis. The analyses strongly supported the hypothesis that H. naledi forms a clade with the other Homo species and Australopithecus sediba. The analyses were more ambiguous regarding the position of H. naledi within the (Homo, Au. sediba) clade. A number of hypotheses were rejected, but several others were not. Based on the available craniodental data, Homo antecessor, Asian Homo erectus, Homo habilis, Homo floresiensis, Homo sapiens, and Au. sediba could all be the sister taxon of H. naledi. According to the dated Bayesian analysis, the most likely age for H. naledi is 912 ka. This age estimate was supported by the resampling analysis. Our findings have a number of implications. Most notably, they support the assignment of the new specimens to Homo, cast doubt on the claim that H. naledi is simply a variant of H. erectus, and suggest H. naledi is younger than has been previously proposed.

  20. Allanite age-dating: Non-matrix-matched standardization in quadrupole LA-ICP-MS

    NASA Astrophysics Data System (ADS)

    Burn, M.; Lanari, P.; Pettke, T.; Engi, M.

    2014-12-01

    Allanite Th-U-Pb age-dating has recently been found to be powerful in unraveling the timing of geological processes such as the metamorphic dynamics in subduction zones and crystallization velocity of magmas. However, inconsistencies among analytical techniques have raised doubts about the accuracy of allanite age data. Spot analysis techniques such as LA-ICP-MS are claimed to be crucially dependent on matrix-matched standards, the quality of which is variable. We present a new approach in LA-ICP-MS data reduction that allows non-matrix-matched standardization via well constrained zircon reference materials as primary standards. Our data were obtained using a GeoLas Pro 193 nm ArF excimer laser ablation system coupled to an ELAN DRC-e quadrupole ICP-MS. We use 32 μm and 24 μm spot sizes; laser operating conditions of 9 Hz repetition rate and 2.5 J/cm2 fluence have proven advantageous. Matrix dependent downhole fractionation evolution is empirically determined by analyzing 208Pb/232Th and 206Pb/238U and applied prior to standardization. The new data reduction technique was tested on three magmatic allanite reference materials (SISSb, CAPb, TARA); within error these show the same downhole fractionation evolution for all allanite types and in different analytical sessions, provided measurement conditions remain the same. Although the downhole evolution of allanite and zircon differs significantly, a link between zircon and allanite matrix is established by assuming CAPb and TARA to be fixed at the corresponding reference ages. Our weighted mean 208Pb/232Th ages are 30.06 ± 0.22 (2σ) for SISSb, 275.4 ± 1.3 (2σ) for CAPb, and 409.9 ± 1.8 (2σ) for TARA. Precision of single spot age data varies between 1.5 and 8 % (2σ), dependent on spot size and common lead concentrations. Quadrupole LA-ICP-MS allanite age-dating has thus similar uncertainties as do other spot analysis techniques. The new data reduction technique is much less dependent on quality and homogeneity

  1. I-Pu-Xe dating and the relative ages of the earth and moon

    NASA Technical Reports Server (NTRS)

    Swindle, T. D.; Caffee, M. W.; Hohenberg, C. M.; Taylor, S. R.

    1986-01-01

    The ages of the earth and moon as determined by various chronometric systems are discussed with primary emphasis placed on the development of an I-Pu-Xe chronometer. Data on excess fission xenon are reviewed with attention given to the strengths and weaknesses of the assumptions required for lunar I-Pu-Xe chronometry. Using I-Pu-Xe dating, it is estimated that the retention of excess fission xenon in lunar samples began no more than 63 + or - 42 m.y. after the time of primitive meteorite formation.

  2. Spectrum Policy in the Age of Broadband: Issues for Congress

    DTIC Science & Technology

    2010-01-29

    homes or convenient public locations, including airports and café environments such as Starbucks . In 2008, there were over 7,000 Starbucks locations...of by a license-holder. 135 “ Starbucks to Expand Technology Relationship with AT&T,” Starbucks Corporation Press Room, February 11, 2008, http...technologies and to formulate new investment strategies . The possibility of allocating additional spectrum for mobile broadband was among the

  3. Ages of Sevier thrusting from dating of metamorphic garnet using the Lu-Hf method

    NASA Astrophysics Data System (ADS)

    Cruz-Uribe, A. M.; Hoisch, T. D.; Wells, M. L.; Vervoort, J. D.

    2008-12-01

    Combined thermodynamic modeling of garnet growth zoning and Lu-Hf dating of garnet yield well-constrained pressure-temperature-time (PTt) paths. Here we present PTt paths from amphibolite-facies pelitic garnet from the Raft River-Albion-Grouse Creek metamorphic core complex that constrain the timing of thrusting in the hinterland of the Sevier thrust belt. Three general times of thrust burial are indicated: 150, 138, and 85 Ma. Lu-Hf garnet dating of burial-related garnet growth in the Raft River Mountains yielded a Late Jurassic age of 149.9 ± 1.2 Ma (2σ, MSWD = 1.1) based on three garnet fractions and a whole rock. A PT path from the schist of Mahogany Peaks in the Albion Range, Idaho, records an isothermal pressure increase indicating growth during thrusting. Lu-Hf dating of garnet from the same rock yielded an Early Cretaceous age of 138.7 ± 0.7 Ma (2σ, MSWD = 1.6) based on seven garnet fractions. An additional PT path from a nearby outcrop also records an isothermal pressure increase and a similar Lu-Hf garnet age of 132.1 ± 5.1 Ma (2σ, MSWD = 9.5) based on three garnet fractions and a whole rock. PT paths of multiple garnet grains from the schist of Stevens Spring in the Grouse Creek Mountains, Utah, exhibit isothermal pressure increases and yielded a Lu-Hf garnet age of 85.5 ± 1.9 Ma (2σ, MSWD = 3.9) based on five garnet fractions and a whole rock. The Late Jurassic burial event recorded in the Raft River Mountains is older than the ages of inception of thrusting of the western thrusts of the Sevier fold-thrust belt including the Canyon Range and Paris - Willard thrusts, but consistent with an eastward progression in initial shortening in the orogenic wedge and development of an inferred thrust load responsible for the retroarc Morrison Formation basin. Early Cretaceous hinterland burial recorded in the Albion Range is permissively coeval with activity on the Willard and Canyon Range thrusts. Finally, renewed hinterland thrust burial during the Late

  4. Impacts of age-dependent tree sensitivity and dating approaches on dendrogeomorphic time series of landslides

    NASA Astrophysics Data System (ADS)

    Šilhán, Karel; Stoffel, Markus

    2015-05-01

    Different approaches and thresholds have been utilized in the past to date landslides with growth ring series of disturbed trees. Past work was mostly based on conifer species because of their well-defined ring boundaries and the easy identification of compression wood after stem tilting. More recently, work has been expanded to include broad-leaved trees, which are thought to produce less and less evident reactions after landsliding. This contribution reviews recent progress made in dendrogeomorphic landslide analysis and introduces a new approach in which landslides are dated via ring eccentricity formed after tilting. We compare results of this new and the more conventional approaches. In addition, the paper also addresses tree sensitivity to landslide disturbance as a function of tree age and trunk diameter using 119 common beech (Fagus sylvatica L.) and 39 Crimean pine (Pinus nigra ssp. pallasiana) trees growing on two landslide bodies. The landslide events reconstructed with the classical approach (reaction wood) also appear as events in the eccentricity analysis, but the inclusion of eccentricity clearly allowed for more (162%) landslides to be detected in the tree-ring series. With respect to tree sensitivity, conifers and broad-leaved trees show the strongest reactions to landslides at ages comprised between 40 and 60 years, with a second phase of increased sensitivity in P. nigra at ages of ca. 120-130 years. These phases of highest sensitivities correspond with trunk diameters at breast height of 6-8 and 18-22 cm, respectively (P. nigra). This study thus calls for the inclusion of eccentricity analyses in future landslide reconstructions as well as for the selection of trees belonging to different age and diameter classes to allow for a well-balanced and more complete reconstruction of past events.

  5. First direct dating of a presumed Pleistocene hominid from China: AMS radiocarbon age of a femur from the Ordos Plateau.

    PubMed

    Keates, Susan G; Hodgins, Gregory W L; Kuzmin, Yaroslav V; Orlova, Lyobov A

    2007-07-01

    Human remains from the Xarusgol Valley, Ordos Plateau, northwestern China, have been considered to date to the Late Pleistocene. In order to ascertain their true age, direct AMS (14)C dating of a femur collected in the early 1920s was conducted. The results demonstrate that the femur is very young, with one sample of 'post-bomb' age and the other sample c. 200 years old. This first direct dating of a Chinese fossil hominid underscores the need to apply the same methodology to other Chinese modern human fossils currently believed to be of Pleistocene age.

  6. Constraints on the age of the Great Sand Dunes, Colorado, from subsurface stratigraphy and OSL dates

    USGS Publications Warehouse

    Madole, Richard F.; Mahan, Shannon; Romig, Joseph H.; Havens, Jeremy C.

    2013-01-01

    The age of the Great Sand Dunes has been debated for nearly 150 yr. Seven ages ranging from Miocene to late Holocene have been proposed for them. This paper presents new information—chiefly subsurface stratigraphic data, OSL dates, and geomorphic evidence—that indicates that the Great Sand Dunes began to form in the latter part of the middle Pleistocene. The dunes overlie a thick wedge of piedmont-slope deposits, which in turn overlies sediment of Lake Alamosa, a paleolake that began to drain about 440 ka. The wedge of piedmont-slope deposits extends westward for at least 23 km and is as much as 60 m thick at a distance of 10 km from the Sangre de Cristo Range. Ostracodes from one well indicate that the eastern shoreline of Lake Alamosa extended to within 4.3 km of where the Great Sand Dunes eventually formed. The time represented by the wedge of piedmont-slope deposits is not known exactly, but the wedge post-dates 440 ka and was in place prior to 130 ka because by then the dunes overlying it were sufficiently close and tall enough to obstruct streams draining from the Sangre de Cristo Range.

  7. Factors That Affect Age of Identification of Children with an Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Adelman, Chana R.; Kubiszyn, Thomas

    2017-01-01

    This study explored factors associated with age of identification of autism spectrum disorder (ASD). Results of a one-way ANOVA indicated differences in age of diagnosis among the four regions in the United States, F(3, 650) = 7.618, p = 0.01. Tukey's post hoc comparisons of the groups indicated that the mean age of diagnosis in the Midwest (M =…

  8. School-Based Social Skills Training for Preschool-Age Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Radley, Keith C.; Hanglein, Jeanine; Arak, Marisa

    2016-01-01

    Individuals with autism spectrum disorder display impairments in social interactions and communication that appear at early ages and result in short- and long-term negative outcomes. As such, there is a need for effective social skills training programs for young children with autism spectrum disorder--particularly interventions capable of being…

  9. Age Dating from Electron Microprobe Analyses of U, Th, and Pb: Geological Advantages and Analytical Difficulties.

    PubMed

    Bowles, John F W

    2015-10-01

    Electron microprobe analysis of U, Th, and Pb in naturally occurring minerals can indicate their age. Where the Pb is entirely due to the radioactive decay of U and Th, the time since mineral formation or equilibration can be calculated. Uraninite (UO2), monazite (REE PO4), zircon (ZrSiO4), and xenotime (YPO4) have been used, the latter containing U and/or Th in minor proportions. Any stable U- or Th-bearing phase can be considered. Careful analysis is required with attention to interferences, background measurement, detection limits, and Pb-free sample preparation. Extended counting times (600 s) at a probe current >200 nA are recommended. Ages can be determined from uraninite older than 2 Ma for a Pb detection limit of 0.02% and up to 700-1,000 Ma, after which Pb can be lost from the structure. The youngest monazite ages permitted by the Pb detection limit are 50-100 Ma and ages greater than 3,000 Ma have been determined. The method does not provide the detail of isotopic methods, but results can be obtained more readily. Examples show dating of cheralite ((Ca,Ce)(Th,Ce)(PO4)2), a rock containing primary and secondary UO2, and a suite of detrital uraninite grains that formed a part of a mineral exploration program.

  10. Between a rock and a soft place: Using optical ages to date ancient clam gardens on the Pacific Northwest.

    PubMed

    Neudorf, Christina M; Smith, Nicole; Lepofsky, Dana; Toniello, Ginevra; Lian, Olav B

    2017-01-01

    Rock-walled archaeological features are notoriously hard to date, largely because of the absence of suitable organic material for radiocarbon dating. This study demonstrates the efficacy of dating clam garden wall construction using optical dating, and uses optical ages to determine how sedimentation rates in the intertidal zone are affected by clam garden construction. Clam gardens are rock-walled, intertidal terraces that were constructed and maintained by coastal First Nation peoples to increase bivalve habitat and productivity. These features are evidence of ancient shellfish mariculture on the Pacific Northwest and, based on radiocarbon dating, date to at least the late Holocene. Optical dating exploits the luminescence signals of quartz or feldspar minerals to determine the last time the minerals were exposed to sunlight (i.e., their burial age), and thus does not require the presence of organic material. Optical ages were obtained from three clam garden sites on northern Quadra Island, British Columbia, and their reliability was assessed by comparing them to radiocarbon ages derived from shells underneath the clam garden walls, as well as below the terrace sediments. Our optical and radiocarbon ages suggest that construction of these clam garden walls commenced between ~1000 and ~1700 years ago, and our optical ages suggest that construction of the walls was likely incremental and increased sedimentation rates in the intertidal zone by up to fourfold. Results of this study show that when site characteristics are not amenable to radiocarbon dating, optical dating may be the only viable geochronometer. Furthermore, dating rock-walled marine management features and their geomorphic impact can lead to significant advances in our understanding of the intimate relationships that Indigenous peoples worldwide developed with their seascapes.

  11. Between a rock and a soft place: Using optical ages to date ancient clam gardens on the Pacific Northwest

    PubMed Central

    Neudorf, Christina M.; Smith, Nicole; Lepofsky, Dana; Toniello, Ginevra; Lian, Olav B.

    2017-01-01

    Rock-walled archaeological features are notoriously hard to date, largely because of the absence of suitable organic material for radiocarbon dating. This study demonstrates the efficacy of dating clam garden wall construction using optical dating, and uses optical ages to determine how sedimentation rates in the intertidal zone are affected by clam garden construction. Clam gardens are rock-walled, intertidal terraces that were constructed and maintained by coastal First Nation peoples to increase bivalve habitat and productivity. These features are evidence of ancient shellfish mariculture on the Pacific Northwest and, based on radiocarbon dating, date to at least the late Holocene. Optical dating exploits the luminescence signals of quartz or feldspar minerals to determine the last time the minerals were exposed to sunlight (i.e., their burial age), and thus does not require the presence of organic material. Optical ages were obtained from three clam garden sites on northern Quadra Island, British Columbia, and their reliability was assessed by comparing them to radiocarbon ages derived from shells underneath the clam garden walls, as well as below the terrace sediments. Our optical and radiocarbon ages suggest that construction of these clam garden walls commenced between ~1000 and ~1700 years ago, and our optical ages suggest that construction of the walls was likely incremental and increased sedimentation rates in the intertidal zone by up to fourfold. Results of this study show that when site characteristics are not amenable to radiocarbon dating, optical dating may be the only viable geochronometer. Furthermore, dating rock-walled marine management features and their geomorphic impact can lead to significant advances in our understanding of the intimate relationships that Indigenous peoples worldwide developed with their seascapes. PMID:28182645

  12. Pesticide and transformation product detections and age-dating relations from till and sand deposits

    USGS Publications Warehouse

    Warner, K.L.; Morrow, W.S.

    2007-01-01

    Pesticide and transformation product concentrations and frequencies in ground water from areas of similar crop and pesticide applications may vary substantially with differing lithologies. Pesticide analysis data for atrazine, metolachlor, alachlor, acetochlor, and cyanazine and their pesticide transformation products were collected at 69 monitoring wells in Illinois and northern Indiana to document occurrence of pesticides and their transformation products in two agricultural areas of differing lithologies, till, and sand. The till is primarily tile drained and has preferential fractured flow, whereas the sand primarily has surface water drainage and primary porosity flow. Transformation products represent most of the agricultural pesticides in ground water regardless of aquifer material - till or sand. Transformation products were detected more frequently than parent pesticides in both the till and sand, with metolachlor ethane sulfonic acid being most frequently detected. Estimated ground-water recharge dates for the sand were based on chlorofluorocarbon analyses. These age-dating data indicate that ground water recharged prior to 1990 is more likely to have a detection of a pesticide or pesticide transformation product. Detections were twice as frequent in ground water recharged prior to 1990 (82%) than in ground water recharged on or after 1990 (33%). The highest concentrations of atrazine, alachlor, metolachlor, and their transformation products, also were detected in samples from ground water recharged prior to 1990. These age/pesticide detection relations are opposite of what would normally be expected, and may be the result of preferential flow and/or ground-water mixing between aquifers and aquitards as evident by the detection of acetochlor transformation products in samples with estimated ground-water ages predating initial pesticide application. ?? 2007 American Water Resources Association.

  13. Radiocarbon Dating and age Inversions in Lake Chapala Late Holocene Sediments, Western Mexico.

    NASA Astrophysics Data System (ADS)

    Zarate-Del Valle, P.; Israde-Alcantara, I.; Ramírez-Sánchez, H.; Gómez-Salazar, S.; Ríos-Donato, N.

    2006-12-01

    Neotectonic Lake Chapala, the major Mexican freshwater reservoir lies at the north and northeast of the Citala Rift and is linked to history of the active Plio-Quaternary Transmexican Volcanic Belt geological province. Eight radiocarbon 14C dates were obtained on shallow sediment samples from a gravity corer (T46) of 5 cm in diameter and 1.7 m long. The core was collected from the western sector of Lake Chapala (103° 15.43' W, 20° 14.45' N) at water depth of 3.7 m (june 2000). In general, shallow sediments (<2m deep) in Lake Chapala are dark and silty with granulometric median ranging from 10 to 50 μm. Major oxides in sediments are: SiO2 (54.05%), Al2O3 (18.94%), Fe2O3 (6.75%) and CaO (2.57%). The major mineralogical composition of sediments is as follows: plagioclases (25.86%), quartz (20.92%), clays (38.5%), carbonates (2.99%) and TiO2 (1.05%). Radiocarbon ages were measured by accelerator mass spectrometry (AMS) and were obtained through the organic carbon fraction extracted from the bulk sediment samples sliced every 20 cm taken from the whole core. Stratigraphically ordered from highest to lowest, the eight ages reported are: 1) 2,000 ±40 yr on sediments at 30 cm deep; 2) 1,920 ±35 yr on sediments at 50 cm deep; 3) 1,900 ±35 yr on sediments at 70 cm deep; 4) 2,080 ±35 yr on sediments at 90 cm deep; 5) 2,090 ±50 yr on sediments at 110 cm deep; 6) 2,190 ±35 yr on sediments at 130 cm deep; 7) 2,050 ±35 yr on sediments at 150 cm deep and, 8) 1,500 ±35 yr on sediments at 170 cm deep. From the top until 70 cm and from 130 to bottom we observe two age inversions; the interval apparently with no age inversions is from 70cm to 130cm. As it is known the age inversions observed may be due to a) ancient carbon being incorporated into the sediment during deposition; b) unrecognized bioturbation, c) Postdepositional alteration and, d) variations in the apparent geological ages of the different chemical phases comprising the total sediment. Basically, the factors

  14. 187Re - 187Os nuclear geochronometry: age dating with permil precision

    NASA Astrophysics Data System (ADS)

    Roller, Goetz

    2016-04-01

    Recently, 187Re - 187Os nuclear geochronometry, a new dating method combining ideas of nuclear astrophysics with geochronology, has successfully been used to calculate two-point-isochron (TPI) ages for Devonian black gas shales using the isotopic signature of an r-process geochronometer as one data point in a TPI diagram [1]. Based upon a nuclear production ratio 187Re/188Os = 5.873, TPI ages were calculated for 12 SDO-1 (Devonian Ohio Shale, Appalachian Basin) aliquants, for which repeated Re-Os measurements are reported in the literature [2]. TPI ages range from 384.5 ± 2.7 Ma (187Os/188Osi = 0.29413 ± 0.00023) to 387.7 ± 2.1 Ma (187Os/188Osi = 0.29407 ± 0.00019) with a mean of 386.67 ± 1.79 Ma). The result is consistent with the isochronous age from the 12 aliquants alone (386 ± 16 Ma, 187Os/188Osi = 0.31±0.31), which is bracketed by U-Pb ages for the Belpre Ash (381.1 ± 3.3 Ma) and the Tioga Ash bed (390.0 ± 2.5 Ma) [3] from the Appalachian Basin. Hence, SDO-1 can be assigned to the Givetian stage (varcus-zone) of the Middle Devonian, close to the Eifelian/Givetian boundary (using the time-scale of [3] or [4]). If an age is calculated from an isochron diagram for the 12 aliquants including the nuclear geochronometer, a permil precision can be achieved, an interesting feature with respect to any effort towards calibrating the Geologic Timescale. Additionally, a Th/U evolution (or: Th/U-time) diagram can be plotted using U-Pb zircon age data and Th/U ratios from volcanic rocks and ashes reported in the literature [3] for specific Devonian samples from the Appalachian Basin. Since the Re-Os age obtained for SDO-1 can also be connected to its Th/U ratio, it turns out, that Th/U ratios might be helpful age indicators, as demonstrated for the Devonian using the U-Pb and Re-Os datasets. [1] Roller (2015), GSA Abstr. with Programs 47, #248-14. [2] Du Vivier et al. (2014), Earth Planet. Sci. Lett. 389, 23 - 33. [3] Tucker et al. (1998), Earth Planet. Sci. Lett

  15. Dating of Holocene lateral moraines in the western Southern Alps, New Zealand, applying Schmidt-hammer exposure-age dating (SHD)

    NASA Astrophysics Data System (ADS)

    Winkler, Stefan

    2014-05-01

    Research on Holocene mountain glacier chronologies has recently intensified due to the importance of mountain glaciers as key indicators for past and present climate change. This progress is closely connected with major improvements in modern dating techniques and the application of multi-proxy approaches adapted to specific local/regional conditions. Despite recent progress there is, however, still a need for better spatial differentiation and a lack of generally accepted concepts for global and inter-hemispheric correlation of Holocene glacier chronologies. Furthermore, the "geomorphological uncertainty" inevitably connected with numerical dating of moraines in neotectonic active mountain ranges characterised by highly dynamic geomorphological process systems requires careful consideration of any subsequent palaeoclimatic interpretation. During the past few years Schmidt-hammer exposure-age dating (SHD) has revealed its potential to successfully challenge those specific circumstances. The Southern Alps of New Zealand have provided one of only a few suitable study sites for investigating Holocene glacier chronologies in the mid-latitudinal Southern Hemisphere. Recent years have seen a significant increase in terrestrial cosmogenic nuclide dating (TCND)-ages published for the Southern Alps, mainly for the last Glaciation, but also for the Holocene. The availability of a regional 10Be-production curve has improved the calibration of TCND-ages. These studies applying TCND alongside previous chronological studies using a variety of different dating techniques focus, however, primarily on a few selected glacier forelands east of the Main Divide in Aoraki/Mt Cook National Park. Bad accessibility and methodological problems account for comparatively few investigations on glacier forelands west of the Main Divide. Chronological studies applying Schmidt-hammer exposure-age dating (SHD) were performed on six glacier forelands in the western part of the Southern Alps

  16. Ground-Water Age Dating in Community Wells in Oswego County, New York

    USGS Publications Warehouse

    Komor, Stephen C.

    2001-01-01

    Officials in Oswego County, in north-central New York, have been concerned about potential contamination of community wells. Many of these wells are completed in unconfined glacial sand-and-gravel aquifers, although some are finished in till or in the underlying fractured and jointed bedrock of Late Ordovician and Early Silurian ages. Local shallow ground-water flow is affected by the orientation and hydraulic characteristics of the local topography and surficial sediments, whereas deeper regional flow is toward Lake Ontario. Concentrations of chlorofluorocarbons and tritium in water samples from 28 wells in the county were measured in 1999 for ground-water-age dating; results yield recharge dates ranging from about 1955 to 1994. The presence of water older than about 15 years in the sand-and-gravel aquifers differs from previous concepts of recharge sources and ground-water movement that were based on numerical modeling of ground-water flow. Young ground water (1 to 5 years old) probably represents recharge from recent precipitation and seepage from streams, whereas the oldest ground water (more than 40 years old) probably is derived from the fractured bedrock that underlies the glacial sediments or has moved along long flow paths in unconsolidated deposits, or through poorly permeable material. Some sand-and-gravel aquifers in Oswego County contain mixtures of old and young water. Wellhead-protection efforts need to focus on protection of the quality of young water in the sand-and-gravel aquifers because young water is more likely to be contaminated than old water.

  17. Microglial Function across the Spectrum of Age and Gender

    PubMed Central

    Nissen, Jillian C.

    2017-01-01

    Microglia constitute the resident immunocompetent cells of the central nervous system. Although much work has focused on their ability to mount an inflammatory response in reaction to pathology, recent studies have delved into their role in maintaining homeostasis in the healthy brain. It is important to note that the function of these cells is more complex than originally conceived, as there is increasing evidence that microglial responses can vary greatly among individuals. Here, this review will describe the changing behavior of microglia from development and birth through to the aged brain. Further, it is not only age that impacts the state of the neuroimmune milieu, as microglia have been shown to play a central role in the sexual differentiation of the brain. Finally, this review will discuss the implications this has for the differences in the incidence of neurodegenerative disorders between males and females, and between the young and old. PMID:28273860

  18. Using Dissolved Organic Carbon Isotopes for Groundwater Age Dating in Southern Nevada, USA

    NASA Astrophysics Data System (ADS)

    Thomas, James; Hershey, Ronald; Fereday, Wyatt

    2016-04-01

    Dissolved organic carbon (DOC) 14C offers a method to calculate groundwater ages that is more straightforward than dissolved inorganic carbon (DIC) 14C. To obtain corrected DIC 14C groundwater ages requires models that account for chemical and physical processes that affect both 13C and 14C. This is especially true in carbonate-rock aquifers where a fair amount of dissolution and precipitation of carbonate minerals can occur. A first important step in calculating 14C DOC groundwater ages is to determine the initial 14C DOC (A0) values of the groundwater recharge. For this study, recharge area groundwater samples of DOC 14C, collected from 14 different sites, were used to determine the recharge DOC 14C values. These values ranged from 96 to 120 percent modern carbon (pmc), with an average value of 106.2 pmc. These 14C A0 values support the use of a 100 pmc 14C A0 pre-bomb value to calculate DOC 14C groundwater ages for southern Nevada. Several conditions to successfully use DOC 14C to date groundwater need to be met. First, soluble organic carbon content of aquifers needs to be low, so that little DOC is added to the groundwater as it flows from recharge areas down gradient in an aquifer. For this study, volcanic and carbonate aquifer outcrop rocks showed that these rocks contained low soluble organic carbon. Second, it is important that the DOC does not change character down a flow path, which could indicate transformation of DOC along a flow path and/or addition of DOC to the groundwater. Although specific DOC compounds could not be identified for samples collected at four sites, all four groundwater sample spectra show the same general shape over the duration of the HPLC run indicating that the DOC compound composition of groundwater does not significantly change from up-gradient to down-gradient. Third, another factor that could greatly affect DOC 14C groundwater age calculations is matrix diffusion/adsorption of DOC 14C. Laboratory experiments showed that

  19. Dating violence victimization across the teen years: Abuse frequency, number of abusive partners, and age at first occurrence

    PubMed Central

    2012-01-01

    Background Prior longitudinal studies have shown high cumulative dating violence exposure rates among U.S adolescents, with 36 percent of males and 44 percent to 88 percent of females experiencing victimization across adolescence/young adulthood. Despite promising information characterizing adolescents’ dating violence experiences longitudinally, prior studies tended to concentrate on physical and sexual types of violence only, and did not report information on the number of times dating violence was experienced across multiple abusive partners. We used a method similar to the timeline follow-back interview to query adolescents about dating violence victimization from age 13 to 19—including dating violence types (physical, sexual, and psychological), frequency, age at first occurrence, and number of abusive partners. Methods A total of 730 subjects were randomly sampled from university registrar records and invited to complete an online survey, which utilized methods similar to the timeline follow-back interview, to retrospectively assess relationship histories and dating violence victimization from age 13 to 19 (eight questions adapted from widely-used surveys covering physical, sexual, and psychological abuse). Then, for each dating violence type, we asked about the number of occurrences, number of abusive partners, and age at first occurrence. Of 341 subjects who completed the survey, we included 297 (64 percent females; 36 percent males) who had a dating partner from age 13 to 19. Results Fully 64.7 percent of females and 61.7 percent of males reported dating violence victimization between age 13 and 19, with most experiencing multiple occurrences. More than one-third of abused females had two or more abusive partners: controlling behavior (35.6 percent); put downs/name calling (37.0); pressured sex (42.9); insults (44.3); slapped/hit (50.0); and threats (62.5). Males also had two or more abusive partners, as follows: controlling behavior (42.1 percent

  20. The Relationship between Gender and Age of First Concern in Toddlers with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Horovitz, Max; Matson, Johnny L.; Turygin, Nicole; Beighley, Jennifer S.

    2012-01-01

    The age at which parents first developed concerns over their child's development was examined in 965 toddlers with autism spectrum disorders (ASD) and atypical development to examine the potential role of gender. A two-way analysis of covariance was conducted with gender and diagnosis entered as independent variables, age at assessment entered as…

  1. Brief Report: Phenotypic Differences and Their Relationship to Paternal Age and Gender in Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Vierck, Esther; Silverman, Jeremy M.

    2015-01-01

    Two modes of inheritance have been proposed in autism spectrum disorder, transmission though pre-existing variants and de novo mutations. Different modes may lead to different symptom expressions in affected individuals. De novo mutations become more likely with advancing paternal age suggesting that paternal age may predict phenotypic…

  2. Social analogical reasoning in school-aged children with autism spectrum disorder and typically developing peers.

    PubMed

    Green, Adam E; Kenworthy, Lauren; Gallagher, Natalie M; Antezana, Ligia; Mosner, Maya G; Krieg, Samantha; Dudley, Katherina; Ratto, Allison; Yerys, Benjamin E

    2017-05-01

    Analogical reasoning is an important mechanism for social cognition in typically developing children, and recent evidence suggests that some forms of analogical reasoning may be preserved in autism spectrum disorder. An unanswered question is whether children with autism spectrum disorder can apply analogical reasoning to social information. In all, 92 children with autism spectrum disorder completed a social content analogical reasoning task presented via photographs of real-world social interactions. Autism spectrum disorder participants exhibited performance that was well above chance and was not significantly worse than age- and intelligence quotient-matched typically developing children. Investigating the relationship of social content analogical reasoning performance to age in this cross-sectional dataset indicated similar developmental trajectories in the autism spectrum disorder and typically developing children groups. These findings provide new support for intact analogical reasoning in autism spectrum disorder and have theoretical implications for analogy as a metacognitive skill that may be at least partially dissociable from general deficits in processing social content. As an initial study of social analogical reasoning in children with autism spectrum disorder, this study focused on a basic research question with limited ecological validity. Evidence that children with autism spectrum disorder can apply analogical reasoning ability to social content may have long-range applied implications for exploring how this capacity might be channeled to improve social cognition in daily life.

  3. Statistical methods to adjust for date and age misreporting to improve estimates of vital rates in Pakistan.

    PubMed

    Pullum, T W

    1991-02-01

    Misreporting of dates and ages poses serious difficulties for the estimation of the age distribution and birth and death rates in many developing countries. The pervasiveness of these problems is illustrated with data from a well-designed on-going survey in Pakistan, the Pakistan Demographic Survey. Methods for reconciling discrepancies, based on the assumptions of constant misreporting and survivorship patterns, are presented. The reasoning behind these methods could be applied much more generally. Research into the cultural interpretations of age and dates, and the nature of possible biases, is called for.

  4. Methods for using argon-39 to age-date groundwater using ultra-low-background proportional counting

    DOE PAGES

    Mace, Emily; Aalseth, Craig; Brandenberger, Jill; ...

    2016-12-21

    Argon-39 can be used as a tracer for age-dating glaciers, oceans, and more recently, groundwater. With a half-life of 269 years, 39Ar fills an intermediate age range gap (50–1,000 years) not currently covered by other common groundwater tracers. Therefore, adding this tracer to the data suite for groundwater studies provides an important tool for improving our understanding of groundwater systems. Lastly, we present the methods employed for arriving at an age-date for a given sample of argon degassed from groundwater.

  5. Methods for using argon-39 to age-date groundwater using ultra-low-background proportional counting

    SciTech Connect

    Mace, Emily; Aalseth, Craig; Brandenberger, Jill; Day, Anthony; Hoppe, Eric; Humble, Paul; Keillor, Martin; Kulongoski, Justin; Overman, Cory; Panisko, Mark; Seifert, Allen; White, Signe; Freeburg, Eric Wilcox; Williams, Richard

    2016-12-21

    Argon-39 can be used as a tracer for age-dating glaciers, oceans, and more recently, groundwater. With a half-life of 269 years, 39Ar fills an intermediate age range gap (50–1,000 years) not currently covered by other common groundwater tracers. Therefore, adding this tracer to the data suite for groundwater studies provides an important tool for improving our understanding of groundwater systems. Lastly, we present the methods employed for arriving at an age-date for a given sample of argon degassed from groundwater.

  6. Methods for using argon-39 to age-date groundwater using ultra-low-background proportional counting.

    PubMed

    Mace, Emily; Aalseth, Craig; Brandenberger, Jill; Day, Anthony; Hoppe, Eric; Humble, Paul; Keillor, Martin; Kulongoski, Justin; Overman, Cory; Panisko, Mark; Seifert, Allen; White, Signe; Wilcox Freeburg, Eric; Williams, Richard

    2016-12-21

    Argon-39 can be used as a tracer for age-dating glaciers, oceans, and more recently, groundwater. With a half-life of 269 years, (39)Ar fills an intermediate age range gap (50-1,000 years) not currently covered by other common groundwater tracers. Therefore, adding this tracer to the data suite for groundwater studies provides an important tool for improving our understanding of groundwater systems. We present the methods employed for arriving at an age-date for a given sample of argon degassed from groundwater.

  7. Radiocarbon Dating

    SciTech Connect

    Buchholz, B A

    2007-12-20

    Radiocarbon dating can be used to determine the age of objects that contain components that were once alive. In the case of human remains, a radiocarbon date can distinguish between a crime scene and an archeological site. Documents, museum artifacts and art objects can be dated to determine if their age is correct for the historical context. A radiocarbon date does not confirm authenticity, but it can help identify a forgery.

  8. Psychiatric Disorders Prior to Dating Initiation and Physical Dating Violence Before Age 21: Findings from the National Comorbidity Survey Replication (NCS-R)

    PubMed Central

    McCauley, Heather L.; Breslau, Joshua A.; Saito, Naomi; Miller, Elizabeth

    2015-01-01

    Purpose Poor mental health is associated with teen dating violence (TDV), but whether there are specific types of psychiatric disorders that could be targeted with intervention to reduce TDV remains unknown. Methods Multivariable logistic regression models were used to assess the associations of psychiatric disorders that emerged prior to dating initiation with subsequent physical dating violence in a nationally representative sample from the National Comorbidity Survey Replication, adjusting statistically for adverse childhood experiences. Results In adjusted models, internalizing disorders (AOR 1.14, 95% CI 1.04, 1.25; no sex differences noted) and externalizing disorders (males: AOR 1.28, 95% CI 1.10, 1.49; females: AOR 1.85, 95% CI 1.55, 2.21) were associated with subsequent involvement in any physical dating violence victimization or perpetration before the age of 21. Those at greatest risk included girls with ADHD and substance use, in particular. Conclusions The range of psychiatric disorders associated with of TDV is broader than has generally been recognized for both boys and girls. Clinical and public health prevention programs should incorporate strategies for addressing multiple pathways through which poor mental health may put adolescents at risk for TDV. PMID:25773524

  9. Advancing knowledge gained from sediment budgets through sediment age dating and fingerprinting in small watersheds

    NASA Astrophysics Data System (ADS)

    Skalak, K.; Benthem, A.; Gellis, A.; Harvey, J. W.; Hupp, C. R.; Larsen, L.; Noe, G. B.; Pizzuto, J. E.; Schenk, E.

    2013-12-01

    Dynamics and long-term trajectories of fine sediment generally remain poorly quantified in rivers, which have implications for nutrient and contaminant transport and remediation strategies. Here we focus on two streams within the Chesapeake Bay watershed, Difficult Run and Accotink Creek. These streams have varying degrees of urbanization and diverse best management practices, making possible a comparison of sediment sources, sinks, and residence times to illuminate how land management impacts fine sediment transport. Bank erosion and floodplain accumulation in Difficult Run has been previously determined and is ongoing in Accotink Creek. Current work advances sediment budgets by quantifying the role of in-channel fine sediment storage in the bed and margins. To understand the relative storage timescales for various geomorphic features (floodplain, in-channel, etc.) and develop age distributions, sediment is dated using radionuclides of varying half-lives such as Pb-210, Cs-137, Be-7, bomb radiocarbon, and optically stimulated luminescence (OSL). To determine the source of sediment that is transported in suspension, sediment fingerprinting has been completed in Difficult Run and initiated in Accotink Creek. Furthermore, the present study furthers our understanding of fine sediment dynamics by fingerprinting sources of stored sediment and evaluating how they evolve over storm events and stream size. For this, we sampled sediment in storage zones before and after storm events of a specified magnitude to determine their chemical signatures with respect to various source-tracking elements and isotopes. This study represents the first such work to integrate sediment dating, sediment fingerprinting and an analysis of storage zones to understand fine sediment dynamics and long-term trajectories.

  10. Age validation of canary rockfish (Sebastes pinniger) using two independent otolith techniques: lead-radium and bomb radiocarbon dating.

    SciTech Connect

    Andrews, A H; Kerr, L A; Cailliet, G M; Brown, T A; Lundstrom, C C; Stanley, R D

    2007-11-04

    Canary rockfish (Sebastes pinniger) have long been an important part of recreational and commercial rockfish fishing from southeast Alaska to southern California, but localized stock abundances have declined considerably. Based on age estimates from otoliths and other structures, lifespan estimates vary from about 20 years to over 80 years. For the purpose of monitoring stocks, age composition is routinely estimated by counting growth zones in otoliths; however, age estimation procedures and lifespan estimates remain largely unvalidated. Typical age validation techniques have limited application for canary rockfish because they are deep dwelling and may be long lived. In this study, the unaged otolith of the pair from fish aged at the Department of Fisheries and Oceans Canada was used in one of two age validation techniques: (1) lead-radium dating and (2) bomb radiocarbon ({sup 14}C) dating. Age estimate accuracy and the validity of age estimation procedures were validated based on the results from each technique. Lead-radium dating proved successful in determining a minimum estimate of lifespan was 53 years and provided support for age estimation procedures up to about 50-60 years. These findings were further supported by {Delta}{sup 14}C data, which indicated a minimum estimate of lifespan was 44 {+-} 3 years. Both techniques validate, to differing degrees, age estimation procedures and provide support for inferring that canary rockfish can live more than 80 years.

  11. [Determination of the amino acid spectrum as an aid in the up-dating of skeletal findings].

    PubMed

    Bonte, W; Johansson, J; Garbe, G; Berg, S

    1976-01-01

    Estimation of the age of skeletal remains is usually based on subjective evaluation of the morphological grade of decomposition. This assumes, that the investigator is provided with pertinent experience. Experimentally elaborated physical and chemical methods proposed for objectification of the statements did not yet assest until today due to lacking temporal correlation. Our investigations were stimulated by observations on fossil bones indicating that the collagenbound amino acids diminish very slowly dependent on geological age. Samples of 53 skeletons of five to 2500 years were pulverized and subjected to acid hydrolysis. The amino acids released from bone collagen were separated by means of thin-layer chromatography and detected by isatin and ninhydrin reagents. The dye complexes of alanine, hydroxyproline, proline, tyrosine, and valine were measured densitometrically and quantified through calibration curves. We established, that the concentrations of the amino acids exhibited a time dependent reduction as equivalent of a loss collagen. The temporal correlation is very narrow (r less than -- 0,8) and sufficient for datings within plus/minus ten years of the more recent bones. Environmental conditions during post-mortem decay seem to have little influence on this process.

  12. School-based social skills training for preschool-age children with autism spectrum disorder.

    PubMed

    Radley, Keith C; Hanglein, Jeanine; Arak, Marisa

    2016-11-01

    Individuals with autism spectrum disorder display impairments in social interactions and communication that appear at early ages and result in short- and long-term negative outcomes. As such, there is a need for effective social skills training programs for young children with autism spectrum disorder-particularly interventions capable of being delivered in educational settings. The study evaluated the effects of the Superheroes Social Skills program on accurate demonstration of social skills in young children with autism spectrum disorder. Two preschool-age children with autism spectrum disorder participated in a weekly social skills intervention. A multiple probe design across skills was used to determine the effects of the intervention. Both participants demonstrated substantial improvements in skill accuracy. Social skills checklists also indicated improvements in social functioning over baseline levels.

  13. [Authentication of Age of Bloodstains Using UV Visible Reflection Spectrum].

    PubMed

    Gao, Qian-yu; Gao, Shi-ming

    2015-08-01

    The age of bloodstains is tightly related to the time elapsed since the crime was committed. The inference of the time that the crime was committed is of great significance to solve the case, and it was also a difficult problem in judicial authentication. Therefore, establishing a method of rapid determination of bleeding time is very necessary. Using a UV-visible spectrometer with a reflection accessory called ISR-240A and whiteboard as a reference standard, the reflection spectra of blood gauze, aluminum, glass and plastic were measured every hour under the condition of 16 °C and 70% humidity within 8 hours. Using SPSS to process the data, R541/R577 was figured out and linear fitting was completed. The same method was carried on on the gauze of blood at 24 °C. The results showed that, within 8 hours, spectral reflectance values of blood at 541 and 577 nm increased gradually with the passage of injury time. In addition to the R2 of the glass with blood is 0.769, the rest of the R2 were greater than 0.900. The values of F were greater than F0.05 (1, 6) = 5.59. Therefore, the linear regression model is significant meaningful. The method of using a UV-Visible spectrometer without doing any operations of the test samples is simple. Moreover, it does no harm to the further inspection in aspects of personal information, which is suitable for the judicial practice.

  14. Parental Age and Risk of Autism Spectrum Disorders in a Finnish National Birth Cohort

    ERIC Educational Resources Information Center

    Lampi, Katja M.; Hinkka-Yli-Salomäki, Susanna; Lehti, Venla; Helenius, Hans; Gissler, Mika; Brown, Alan S.; Sourander, Andre

    2013-01-01

    Aim of the study was to examine the associations between parental age and autism spectrum disorders (ASD). Data were based on the FIPS-A (Finnish Prenatal Study of Autism and Autism Spectrum Disorders), a case-control study with a total of 4,713 cases with childhood autism (n = 1,132), Asperger's syndrome (n = 1,785) or other pervasive…

  15. Pliocene Cosmogenic Nuclide Burial Ages of the Nenana Gravel: Progress in Dating and Implications for Alaska Range Evolution

    NASA Astrophysics Data System (ADS)

    Goehring, B. M.; Bemis, S. P.; Ward, D.; Caffee, M. W.; Sortor, R. N.

    2015-12-01

    The Nenana Gravel is an up to 1.2 km thick foreland basin deposit that spans the north flank of the Alaska Range. It is uplifted relative to the active foreland basin to the north. It is also deformed to various degree dependent on its location within the northern Alaska Range thrust system. Because this foreland basin sequence records the unroofing and northward propagation of the Alaska Range, direct dating of the Nenana Gravel, especially over wide spatial distribution along the Alaska Range, will substantially advance our understanding of the style and timing of deformation of the Alaska Range. At present though, age estimates for the Nenana Gravel are limited to a single maximum limiting age and uncertain minimum limiting age with no little or no insight as to the spatial variation in Nenana Gravel deposition timing. We present the first direct dates of deposition ages of the Nenana Gravel using cosmogenic nuclide burial dating. Results indicate that deposition of the Nenana Gravel began ca. 6.5 Ma, in stratigraphic agreement with a maximum limiting tephra age from the underlying Usibelli Group. Additional samples from the Nenana Gravel basal contact and higher in the section are presently underway. The resultant burial ages are amongst the oldest 26Al-10Be burial ages ever produced and highlight the potential of the method to directly date sediments in the Pliocene, particularly given recent advancements in the accelerator mass spectrometry measurement of 26Al/27Al isotope ratios.

  16. Age-related temporal and parietal cortical thinning in autism spectrum disorders.

    PubMed

    Wallace, Gregory L; Dankner, Nathan; Kenworthy, Lauren; Giedd, Jay N; Martin, Alex

    2010-12-01

    Studies of head size and brain volume in autism spectrum disorders have suggested that early cortical overgrowth may be followed by prematurely arrested growth. However, the few investigations quantifying cortical thickness have yielded inconsistent results, probably due to variable ages and/or small sample sizes. We assessed differences in cortical thickness between high-functioning adolescent and young adult males with autism spectrum disorders (n = 41) and matched typically developing males (n = 40). We hypothesized thinner cortex, particularly in frontal, parietal and temporal regions, for individuals with autism spectrum disorders in comparison with typically developing controls. Furthermore, we expected to find an age × diagnosis interaction: with increasing age, more pronounced cortical thinning would be observed in autism spectrum disorders than typically developing participants. T(1)-weighted magnetization prepared rapid gradient echo 3 T magnetic resonance imaging scans were acquired from high-functioning males with autism spectrum disorders and from typically developing males matched group-wise on age (range 12-24 years), intelligence quotient (≥ 85) and handedness. Both gyral-level and vertex-based analyses revealed significantly thinner cortex in the autism spectrum disorders group that was located predominantly in left temporal and parietal regions (i.e. the superior temporal sulcus, inferior temporal, postcentral/superior parietal and supramarginal gyri). These findings remained largely unchanged after controlling for intelligence quotient and after accounting for psychotropic medication usage and comorbid psychopathology. Furthermore, a significant age × diagnosis interaction was found in the left fusiform/inferior temporal cortex: participants with autism spectrum disorders had thinner cortex in this region with increasing age to a greater degree than did typically developing participants. Follow-up within group comparisons revealed significant

  17. 230Th-234U Age-Dating Uranium by Mass Spectrometry

    SciTech Connect

    Williams, R W; Gaffney, A M

    2012-04-18

    This is the standard operating procedure used by the Isotope Ratio Mass Spectrometry Group of the Chemical Sciences Division at LLNL for the preparation of a sample of uranium oxide or uranium metal for {sup 230}Th-{sup 234}U age-dating. The method described here includes the dissolution of a sample of uranium oxide or uranium metal, preparation of a secondary dilution, spiking of separate aliquots for uranium and thorium isotope dilution measurements, and purification of uranium and thorium aliquots for mass spectrometry. This SOP may be applied to uranium samples of unknown purity as in a nuclear forensic investigation, and also to well-characterized samples such as, for example, U{sub 3}O{sub 8} and U-metal certified reference materials. The sample of uranium is transferred to a quartz or PFA vial, concentrated nitric acid is added and the sample is heated on a hotplate at approximately 100 C for several hours until it dissolves. The sample solution is diluted with water to make the solution approximately 4 M HNO{sub 3} and hydrofluoric acid is added to make it 0.05 M HF. A secondary dilution of the primary uranium solution is prepared. Separate aliquots for uranium and thorium isotope dilution measurements are taken and spiked with {sup 233}U and {sup 229}Th, respectively. The spiked aliquot for uranium isotope dilution analysis is purified using EiChrom UTEVA resin. The spiked aliquot for thorium isotope dilution analysis is purified by, first, a 1.8 mL AG1x8 resin bed in 9 M HCl on which U adsorbs and Th passes through; second, adsorbing Th on a 1 mL AG1x8 resin bed in 8 M HNO{sub 3} and then eluting it with 9 M HCl followed by 0.1 M HCl + 0.005 M HF; and third, by passing the Th through a final 1.0 mL AG1x8 resin bed in 9 M HCl. The mass spectrometry is performed using the procedure 'Th and U Mass Spectrometry for {sup 230}Th-{sup 234}U Age Dating'.

  18. Reconstruction of settlement phases at Intermediate Bronze Age structures in the Negev Highlands (Israel) using luminescence dating

    NASA Astrophysics Data System (ADS)

    Junge, Andrea; Lomax, Johanna; Shahack-Gross, Ruth; Dunseth, Zachary C.; Finkelstein, Israel; Fuchs, Markus

    2016-04-01

    OSL dating is usually applied to sediments in paleoenvironmental sciences. However, there is only limited experience with determining the age of archaeological stone structures by OSL using dust deposits associated with these structures. The age of trapped dust deposits may be used to date the onset of settlement (sediment below structures), settlement activity (occupation layer), or the time after settlement (sediment between collapsed walls and roofs). In this study, OSL dating is applied for establishing a chronology of settlement structures situated in the Negev Highlands, Israel. Two archaeological sites are investigated to identify the occupation history, by dating the aeolian dust trapped within the remains of ancient buildings. OSL dating techniques are applied using coarse grain quartz and a standard SAR protocol. First results indicate that the luminescence properties of the trapped sediments are suitable for OSL dating. Therefore, it was possible to date the onset of sedimentation in a later phase of the human occupation or shortly after the settlement was abandoned, which is supported by archaeological evidence gained from pottery finds and the architecture of the buildings.

  19. Age of Barrier Canyon-style rock art constrained by cross-cutting relations and luminescence dating techniques.

    PubMed

    Pederson, Joel L; Chapot, Melissa S; Simms, Steven R; Sohbati, Reza; Rittenour, Tammy M; Murray, Andrew S; Cox, Gary

    2014-09-09

    Rock art compels interest from both researchers and a broader public, inspiring many hypotheses about its cultural origin and meaning, but it is notoriously difficult to date numerically. Barrier Canyon-style (BCS) pictographs of the Colorado Plateau are among the most debated examples; hypotheses about its age span the entire Holocene epoch and previous attempts at direct radiocarbon dating have failed. We provide multiple age constraints through the use of cross-cutting relations and new and broadly applicable approaches in optically stimulated luminescence dating at the Great Gallery panel, the type section of BCS art in Canyonlands National Park, southeastern Utah. Alluvial chronostratigraphy constrains the burial and exhumation of the alcove containing the panel, and limits are also set by our related research dating both a rockfall that removed some figures and the rock's exposure duration before that time. Results provide a maximum possible age, a minimum age, and an exposure time window for the creation of the Great Gallery panel, respectively. The only prior hypothesis not disproven is a late Archaic origin for BCS rock art, although our age result of A.D. ∼ 1-1100 coincides better with the transition to and rise of the subsequent Fremont culture. This chronology is for the type locality only, and variability in the age of other sites is likely. Nevertheless, results suggest that BCS rock art represents an artistic tradition that spanned cultures and the transition from foraging to farming in the region.

  20. Age of Barrier Canyon-style rock art constrained by cross-cutting relations and luminescence dating techniques

    NASA Astrophysics Data System (ADS)

    Pederson, Joel L.; Chapot, Melissa S.; Simms, Steven R.; Sohbati, Reza; Rittenour, Tammy M.; Murray, Andrew S.; Cox, Gary

    2014-09-01

    Rock art compels interest from both researchers and a broader public, inspiring many hypotheses about its cultural origin and meaning, but it is notoriously difficult to date numerically. Barrier Canyon-style (BCS) pictographs of the Colorado Plateau are among the most debated examples; hypotheses about its age span the entire Holocene epoch and previous attempts at direct radiocarbon dating have failed. We provide multiple age constraints through the use of cross-cutting relations and new and broadly applicable approaches in optically stimulated luminescence dating at the Great Gallery panel, the type section of BCS art in Canyonlands National Park, southeastern Utah. Alluvial chronostratigraphy constrains the burial and exhumation of the alcove containing the panel, and limits are also set by our related research dating both a rockfall that removed some figures and the rock's exposure duration before that time. Results provide a maximum possible age, a minimum age, and an exposure time window for the creation of the Great Gallery panel, respectively. The only prior hypothesis not disproven is a late Archaic origin for BCS rock art, although our age result of A.D. ∼1-1100 coincides better with the transition to and rise of the subsequent Fremont culture. This chronology is for the type locality only, and variability in the age of other sites is likely. Nevertheless, results suggest that BCS rock art represents an artistic tradition that spanned cultures and the transition from foraging to farming in the region.

  1. Age of Barrier Canyon-style rock art constrained by cross-cutting relations and luminescence dating techniques

    PubMed Central

    Pederson, Joel L.; Chapot, Melissa S.; Simms, Steven R.; Sohbati, Reza; Rittenour, Tammy M.; Murray, Andrew S.; Cox, Gary

    2014-01-01

    Rock art compels interest from both researchers and a broader public, inspiring many hypotheses about its cultural origin and meaning, but it is notoriously difficult to date numerically. Barrier Canyon-style (BCS) pictographs of the Colorado Plateau are among the most debated examples; hypotheses about its age span the entire Holocene epoch and previous attempts at direct radiocarbon dating have failed. We provide multiple age constraints through the use of cross-cutting relations and new and broadly applicable approaches in optically stimulated luminescence dating at the Great Gallery panel, the type section of BCS art in Canyonlands National Park, southeastern Utah. Alluvial chronostratigraphy constrains the burial and exhumation of the alcove containing the panel, and limits are also set by our related research dating both a rockfall that removed some figures and the rock’s exposure duration before that time. Results provide a maximum possible age, a minimum age, and an exposure time window for the creation of the Great Gallery panel, respectively. The only prior hypothesis not disproven is a late Archaic origin for BCS rock art, although our age result of A.D. ∼1–1100 coincides better with the transition to and rise of the subsequent Fremont culture. This chronology is for the type locality only, and variability in the age of other sites is likely. Nevertheless, results suggest that BCS rock art represents an artistic tradition that spanned cultures and the transition from foraging to farming in the region. PMID:25157162

  2. Common-Lead Corrected U-Pb Age Dating of Perovskite by LA-SF-ICP-MS

    NASA Astrophysics Data System (ADS)

    Frei, D.

    2014-12-01

    Perovskite is a very useful mineral for dating the age of emplacement of kimberlites and associated rocks. Conventionally, U-Pb dating of perovskite is achieved using isotope dilution (ID-TIMS) or ion-probe (SHRIMP) techniques, which are time- and cost-intensive. The potential of the rapid and inexpensive laser ablation ICP-MS technique for U-Pb dating of perovskite has been demonstrated recently. We investigated the benefits of single collector magnetic sectorfield ICP-MS (SF-ICP-MS) instruments for U-Pb dating of perovskite by laser ablation. To this end perovskites from two kimberlites from Garnet Lake, W Greenland, and Pyramidefjeld, SW Greenland, have been separated. Multigrain aliquots of both perovskite separates were U-Pb dated by ID-TIMS, yielding emplacement ages of 568 ±11 Ma for the Garnet Lake kimberlite and 151 ±2 Ma for the Pyramidefjeld kimberlite. Subsequently both samples have been dated in-situ by laser ablation employing a ThermoFinnigan Element2 SF-ICP-MS coupled to a NewWave UP 213 laser system. A common lead correction was applied based on the measured 204Pb intensity (after correction for the measured 204(Pb+Hg) gas blank). Perovskite from the Ice River Complex, British Columbia, was used as a secondary standard for quality control purposes. Multiple in-situ measurements of the Ice River perovskite in two different analytical sessions yielded concordia ages of 359 ±3 Ma and 357 ±3 Ma, in excellent agreement with the age of 356 Ma determined by ID-TIMS (Heaman, pers. comm.). Nineteen in-situ analyses of perovskite grains extracted from the Garnet Lake kimberlite yielded a concordia age of 566 ±5 Ma, also in excellent agreement with the age obtained by ID-TIMS. Because of the very low Pb contents in perovskites from the Pyramidefjeld (around 1 ppm) and the associated large uncertainties of the common lead correction, no concordia age could be obtained. However, the in-situ laser ablation analysis yielded a common lead corrected weighted

  3. In Situ Geochemical Analysis and Age Dating of Rocks Using Laser Ablation-Miniature Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Sinha, Mahadeva P.; Hecht, Michael H.; Hurowitz, Joel A.

    2012-01-01

    A miniaturized instrument for performing chemical and isotopic analysis of rocks has been developed. The rock sample is ablated by a laser and the neutral species produced are analyzed using the JPL-invented miniature mass spectrometer. The direct sampling of neutral ablated material and the simultaneous measurement of all the elemental and isotopic species are the novelties of this method. In this laser ablation-miniature mass spectrometer (LA-MMS) method, the ablated neutral atoms are led into the electron impact ionization source of the MMS, where they are ionized by a 70-eV electron beam. This results in a secondary ion pulse typically 10-100 microsecond wide, compared to the original 5-10-nanosecond laser pulse duration. Ions of different masses are then spatially dispersed along the focal plane of the magnetic sector of the miniature mass spectrometer and measured in parallel by a modified CCD (charge-coupled device) array detector capable of detecting ions directly. Compared to conventional scanning techniques, simultaneous measurement of the ion pulse along the focal plane effectively offers a 100% duty cycle over a wide mass range. LAMMS offers a more quantitative assessment of elemental composition than techniques that detect laser-ionized species produced directly in the ablation process because the latter can be strongly influenced by matrix effects that vary with the structure and geometry of the surface, the laser beam, and the ionization energies of the elements. The measurement of high-precision isotopic ratios and elemental composition of different rock minerals by LAMMS method has been demonstrated. The LA-MMS can be applied for the absolute age determination of rocks. There is no such instrument available presently in a miniaturized version that can be used for NASA space missions. Work is in progress in the laboratory for geochronology of rocks using LA-MMS that is based on K-Ar radiogenic dating technique.

  4. Longitudinal Volumetric Brain Changes in Autism Spectrum Disorder Ages 6–35 Years

    PubMed Central

    Lange, Nicholas; Travers, Brittany G.; Bigler, Erin D.; Prigge, Molly B.D.; Froehlich, Alyson L.; Nielsen, Jared A.; Cariello, Annahir N.; Zielinski, Brandon A.; Anderson, Jeffrey S.; Fletcher, P. Thomas; Alexander, Andrew A.; Lainhart, Janet E.

    2014-01-01

    LAY ABSTRACT Since the impairments associated with autism spectrum disorder (ASD) tend to persist or worsen from childhood into adulthood, it is of critical importance to examine how the brain develops over this growth epoch. We report initial findings on whole and regional longitudinal brain development in 100 male participants with ASD (226 high-quality MRI scans) compared to 56 typically developing male controls (TDCs) (117 high-quality scans) from childhood into adulthood, for a total of 156 participants scanned over an eight-year period. We provide volumetric growth curves for the entire brain, total gray matter (GM), frontal GM, temporal GM, parietal GM, occipital GM, total cortical white matter (WM), corpus callosum, caudate, thalamus, total cerebellum, and total ventricles. Mean volume of cortical WM was reduced significantly. Decreases in regional mean volumes in the ASD sample were most often due to decreases during late adolescence and adulthood. The growth curve of whole-brain volume showed increased volumes in young children with autism and subsequently decreased during adolescence to meet the TDC curve between 10 and 15 years of age. The volume of many structures continued to decline atypically into adulthood in the ASD sample. The data suggest that ASD is a dynamic disorder with complex changes in whole and regional brain volumes that change over time from childhood into adulthood. SCIENTIFIC ABSTRACT Since the impairments associated with autism spectrum disorder (ASD) tend to persist or worsen from childhood into adulthood, it is of critical importance to examine how the brain develops over this growth epoch. We report initial findings on whole and regional longitudinal brain development in 100 male participants with ASD (226 high-quality MRI scans; mean inter-scan interval 2.7 years) compared to 56 typically developing male controls (TDCs) (117 high-quality scans; mean inter-scan interval 2.6 years) from childhood into adulthood, for a total of 156

  5. The Effect of Gestational Age on Symptom Severity in Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Movsas, Tammy Z.; Paneth, Nigel

    2012-01-01

    Between 2006 and 2010, two research-validated instruments, Social Communication Questionnaire (SCQ) and Social Responsiveness Scale (SRS) were filled out online by 4,188 mothers of Autism Spectrum Disorder (ASD) children, aged 4-21, as part of voluntary parental participation in a large web-based registry. Univariate and multivariate linear…

  6. Age of Parental Concern, Diagnosis, and Service Initiation among Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Zablotsky, Benjamin; Colpe, Lisa J.; Pringle, Beverly A.; Kogan, Michael D.; Rice, Catherine; Blumberg, Stephen J.

    2017-01-01

    Children with autism spectrum disorder (ASD) require substantial support to address the core symptoms of ASD and co-occurring behavioral/developmental conditions. This study explores the early diagnostic experiences of school-aged children with ASD using survey data from a large probability-based national sample. Multivariate linear regressions…

  7. Factors Affecting the Age at Diagnosis of Autism Spectrum Disorders in Nova Scotia, Canada

    ERIC Educational Resources Information Center

    Frenette, Priscilla; Dodds, Linda; MacPherson, Kathleen; Flowerdew, Gordon; Hennen, Brian; Bryson, Susan

    2013-01-01

    While early diagnosis of autism spectrum disorders (ASD) is essential for ensuring timely access to early intervention services, there is limited existing literature investigating factors that delay this diagnosis. This population-based cohort study explored the age at which children in Nova Scotia, Canada, are diagnosed with ASDs and the factors…

  8. Neurocognitive and Behavioral Outcomes of Younger Siblings of Children with Autism Spectrum Disorder at Age Five

    ERIC Educational Resources Information Center

    Warren, Zachary E.; Foss-Feig, Jennifer H.; Malesa, Elizabeth E.; Lee, Evon Batey; Taylor, Julie Lounds; Newsom, Cassandra R.; Crittendon, Julie; Stone, Wendy L.

    2012-01-01

    Later-born siblings of children with Autism Spectrum Disorders (ASD) are at increased risk for ASD as well as qualitatively similar traits not meeting clinical cutoffs for the disorder. This study examined age five neurocognitive and behavioral outcomes of 39 younger siblings of children with ASD (Sibs-ASD) and 22 younger siblings of typically…

  9. An evaluation of fossil tip-dating versus node-age calibrations in tetraodontiform fishes (Teleostei: Percomorphaceae).

    PubMed

    Arcila, Dahiana; Alexander Pyron, R; Tyler, James C; Ortí, Guillermo; Betancur-R, Ricardo

    2015-01-01

    Time-calibrated phylogenies based on molecular data provide a framework for comparative studies. Calibration methods to combine fossil information with molecular phylogenies are, however, under active development, often generating disagreement about the best way to incorporate paleontological data into these analyses. This study provides an empirical comparison of the most widely used approach based on node-dating priors for relaxed clocks implemented in the programs BEAST and MrBayes, with two recently proposed improvements: one using a new fossilized birth-death process model for node dating (implemented in the program DPPDiv), and the other using a total-evidence or tip-dating method (implemented in MrBayes and BEAST). These methods are applied herein to tetraodontiform fishes, a diverse group of living and extinct taxa that features one of the most extensive fossil records among teleosts. Previous estimates of time-calibrated phylogenies of tetraodontiforms using node-dating methods reported disparate estimates for their age of origin, ranging from the late Jurassic to the early Paleocene (ca. 150-59Ma). We analyzed a comprehensive dataset with 16 loci and 210 morphological characters, including 131 taxa (95 extant and 36 fossil species) representing all families of fossil and extant tetraodontiforms, under different molecular clock calibration approaches. Results from node-dating methods produced consistently younger ages than the tip-dating approaches. The older ages inferred by tip dating imply an unlikely early-late Jurassic (ca. 185-119Ma) origin for this order and the existence of extended ghost lineages in their fossil record. Node-based methods, by contrast, produce time estimates that are more consistent with the stratigraphic record, suggesting a late Cretaceous (ca. 86-96Ma) origin. We show that the precision of clade age estimates using tip dating increases with the number of fossils analyzed and with the proximity of fossil taxa to the node under

  10. Dating a Small Impact Crater: An Age of Kaali Crater (Estonia) Based on Charcoal Emplaced Within Proximal Ejecta

    NASA Astrophysics Data System (ADS)

    Losiak, A.; Wild, E. M.; Geppert, W. D.; Huber, M. S.; Jõeleht, A.; Kriiska, A.; Kulkov, A.; Paavel, K.; Pirkovic, I.; Plado, J.; Steier, P.; Välja, R.; Wilk, J.; Wisniowski, T.; Zanetti, M.

    2015-09-01

    The Kaali crater was formed shortly after (tpq) 1530-1455 BC (3237 ± 10 14C yr BP). This age is based on dating charcoal within the ejecta blanket that makes it directly related to the impact, and not susceptible to potential reservoir effects.

  11. Brief Report: Phenotypic Differences and their Relationship to Paternal Age and Gender in Autism Spectrum Disorder.

    PubMed

    Vierck, Esther; Silverman, Jeremy M

    2015-06-01

    Two modes of inheritance have been proposed in autism spectrum disorder, transmission though pre-existing variants and de novo mutations. Different modes may lead to different symptom expressions in affected individuals. De novo mutations become more likely with advancing paternal age suggesting that paternal age may predict phenotypic differences. To test this possibility we measured IQ, adaptive behavior, and autistic symptoms in 830 probands from simplex families. We conducted multiple linear regression analysis to estimate the predictive value of paternal age, maternal age, and gender on behavioral measures and IQ. We found a differential effect of parental age and sex on repetitive and restricted behaviors. Findings suggest effects of paternal age on phenotypic differences in simplex families with ASD.

  12. Attention and written expression in school-age, high-functioning children with autism spectrum disorders.

    PubMed

    Zajic, Matthew C; McIntyre, Nancy; Swain-Lerro, Lindsay; Novotny, Stephanie; Oswald, Tasha; Mundy, Peter

    2016-12-09

    High-functioning children with autism spectrum disorders often find writing challenging. These writing difficulties may be specific to autism spectrum disorder or to a more general clinical effect of attention disturbance, as these children are often comorbid for attention-deficit/hyperactivity disorder (ADHD) symptomatology (and children with attention-deficit/hyperactivity disorder often also find writing challenging). To examine this issue, this study investigated the role of attention disturbance on writing in 155 school-age children across four diagnostic groups: high-functioning autism spectrum disorder (HFASD) with lower ADHD symptoms (HFASD-L), HFASD with higher ADHD symptoms (HFASD-H), ADHD symptoms but no autism spectrum disorder symptoms, and typical development. Both HFASD subgroups and the ADHD group displayed lower word production writing scores than the typical development group, but the clinical groups did not differ. The HFASD-H and ADHD groups had significantly lower theme development and text organization writing scores than the typical development group, but the HFASD-L and typical development groups were not significantly different. The findings support prior research reporting writing problems in children with autism spectrum disorder but also suggest that children with HFASD-H may be at greater risk for writing difficulties than children with HFASD-L. Better understanding the role of attention in writing development could advance methods for assessment and intervention for children with high-functioning autism spectrum disorder at risk for writing difficulties.

  13. Radiometric dating of the Earlier Stone Age sequence in excavation I at Wonderwerk Cave, South Africa: preliminary results.

    PubMed

    Chazan, Michael; Ron, Hagai; Matmon, Ari; Porat, Naomi; Goldberg, Paul; Yates, Royden; Avery, Margaret; Sumner, Alexandra; Horwitz, Liora Kolska

    2008-07-01

    We present here the results of 44 paleomagnetic measurements, and single cosmogenic burial and optically stimulated luminescence ages for the Earlier Stone Age deposits from Wonderwerk Cave, Northern Cape, South Africa. The resulting paleomagnetic sequence: N>R>N>R>N constrains the Earlier Stone Age strata in this part of the site to between approximately 0.78-1.96 Ma. A single cosmogenic date of approximately 2.0 Ma from the base of the section offers some corroboration for the paleomagnetic sequence. Preliminary results indicate that the small lithic assemblage from the basal stratum may contain an Oldowan facies. This is overlain by several strata containing Acheulean industries. The preliminary radiometric dates reported here place the onset of the Acheulean at this site to approximately 1.6 Ma, which is roughly contemporaneous with that of East Africa.

  14. New uppermost Cambrian U-Pb date from Avalonian Wales and age of the Cambrian-Ordovician boundary

    USGS Publications Warehouse

    Davidek, K.; Landing, E.; Bowring, S.A.; Westrop, S.R.; Rushton, A.W.A.; Fortey, R.A.; Adrain, J.M.

    1998-01-01

    A crystal-rich volcaniclastic sandatone in the lower Peltura scarabaeoides Zone at Ogof-odi near Criccieth, North Wales, yields a U-Pb zircon age of 491 ?? 1 Ma. This late Late Cambrian date indicates a remarkably young age for the Cambrian-Ordovician boundary whose age must be less than 491 Ma. Hence the revised duration of the post-Placentian (trilobite-bearing) Cambrian indicates that local trilobite zonations allow a biostratigraphic resolution comparble to that provided by Ordovician graptolites and Mesozoic ammonites.

  15. Uranium-series dating of mollusks and corals, and age of Pleistocene deposits, Chesapeake Bay area, Virginia and Maryland

    USGS Publications Warehouse

    Mixon, Robert B.; Szabo, B. J.; Owens, James Patrick

    1982-01-01

    Geologic mapping in conjunction with uranium-series dating of fossil mollusks and corals suggests that the low-lying ( < 17 m in altitude) terrace deposits in the central and southern Chesapeake Bay area include two main depositional sequences, each of which represents a high stand of the sea in late Pleistocene time. The older depositional sequence includes the Accomack and Omar beds of the Delmarva area, the fossiliferous deposits along the lower Rappahannock River, and the Norfolk Formation deposits west of the Suffolk scarp. These beds have yielded a single reliable coral age estimate of 184,000?20,000 years B.P., suggesting an early late Pleistocene age. The younger sequence, including the type beds of the Norfolk Formation and equivalent strata east of the Suffolk scarp, has yielded several coral ages ranging from about 62,000 to 86,000 years B.P. (including ages from our samples and previously reported age estimates); thus, it is clearly late Pleistocene in age. Groupings of ages obtained from our quahog analyses also suggest two transgressive sequences; however, the estimated quahog ages are consistently younger than ages based on coral samples from the same and equivalent stratigraphic units. Stratigraphic, paleoclimatic, and geomorphic data suggest that the estimated uranium-series age of 71,000?7,000 years B.P. for the type beds of the Norfolk, obtained by averaging our coral dates, may be too young by as much as several tens of thousands of years. A postulated equivalency of the type Norfolk beds, upper Pleistocene deposits near Charleston, S.C. (apparent uranium-series age = 95,000?5,000 years), and deposits in the Caribbean area thought to represent the highest sea stand during the last interglacial period (apparent age, 125,000?10,000 years) implies diagenetic modification of coralline material possibly in part because of regional differences in depositional and postdepositional environments.

  16. Confirmation of a late middle Pleistocene age for the Omo Kibish 1 cranium by direct uranium-series dating.

    PubMed

    Aubert, Maxime; Pike, Alistair W G; Stringer, Chris; Bartsiokas, Antonis; Kinsley, Les; Eggins, Stephen; Day, Michael; Grün, Rainer

    2012-11-01

    While it is generally accepted that modern humans evolved in Africa, the specific physical evidence for that origin remains disputed. The modern-looking Omo 1 skeleton, discovered in the Kibish region of Ethiopia in 1967, was controversially dated at ~130 ka (thousands of years ago) by U-series dating on associated Mollusca, and it was not until 2005 that Ar-Ar dating on associated feldspar crystals in pumice clasts provided evidence for an even older age of ~195 ka. However, questions continue to be raised about the age and stratigraphic position of this crucial fossil specimen. Here we present direct U-series determinations on the Omo 1 cranium. In spite of significant methodological complications, which are discussed in detail, the results indicate that the human remains do not belong to a later intrusive burial and are the earliest representative of anatomically modern humans. Given the more archaic morphology shown by the apparently contemporaneous Omo 2 calvaria, we suggest that direct U-series dating is applied to this fossil as well, to confirm its age in relation to Omo 1.

  17. Food selectivity in children with and without an autism spectrum disorder: investigation of diagnosis and age.

    PubMed

    Beighley, Jennifer S; Matson, Johnny L; Rieske, Robert D; Adams, Hilary L

    2013-10-01

    Feeding problems are common in children with autism spectrum disorders (ASDs), with food selectivity being the most frequently reported. Selectivity based on type and/or texture of food is of concern in those with ASD. Variations in symptom presentation of food selectivity in children with different autism spectrum diagnoses across childhood have not often been investigated. Parent-report of food selectivity was examined in 525 children age 2-18 years diagnosed with autistic disorder, PDD-NOS, Asperger's disorder, atypical development, and typical development using information garnered from the Autism Spectrum Disorder-Comorbidity for Children (ASD-CC), a tool to assess emotional issues and comorbid psychopathology. Individuals with an ASD were reported to have significantly more food selectivity than both the atypically developing group and the typically developing group. In addition, the ASD groups, when looked at together, showed a decrease in food selectivity across childhood with significant decrease in the Asperger's disorder group.

  18. SPECTRUM: A Training and Treatment Program for Continuous Glucose Monitoring for All Age Groups.

    PubMed

    Gehr, Bernhard; Holder, Martin; Kulzer, Bernhard; Lange, Karin; Liebl, Andreas; Sahm, Claudia; von Sengbusch, Simone; Schlüter, Sandra; Siegmund, Thorsten; Thurm, Ulrike; Ziegler, Ralph; Freckmann, Guido; Heinemann, Lutz

    2016-08-10

    Optimal usage of continuous glucose monitoring (CGM) requires adequate preparation and training. Patients using a CGM system without special training often do not achieve their intended improvement of metabolic control or even stop using the system due to disappointing results. For this reason a structured training program called "SPECTRUM" was developed in Germany to ensure a high-quality standard for the use of CGM systems. This program is suitable for patients of all age groups and is applicable to all CGM systems and all forms of insulin therapy. Structured curricula (adults, parents of young children, adolescents) have been developed enabling diabetes centers with less experience to offer comprehensive CGM training. Key requirements of SPECTRUM were independency of manufacturers and product neutrality enabling certification for reimbursement after formal evaluation within the framework of a large clinical trial. SPECTRUM was published in January 2016 in German, and translations into other languages are planned.

  19. 235U–231Pa age dating of uranium materials for nuclear forensic investigations

    SciTech Connect

    Eppich, Gary R.; Williams, Ross W.; Gaffney, Amy M.; Schorzman, Kerri C.

    2013-04-03

    Here, age dating of nuclear material can provide insight into source and suspected use in nuclear forensic investigations. We report here a method for the determination of the date of most recent chemical purification for uranium materials using the 235U-231Pa chronometer. Protactinium is separated from uranium and neptunium matrices using anion exchange resin, followed by sorption of Pa to an SiO2 medium. The concentration of 231Pa is measured by isotope dilution mass spectrometry using 233Pa spikes prepared from an aliquot of 237Np and calibrated in-house using the rock standard Table Mountain Latite and the uranium isotopic standard U100. Combined uncertainties of age dates using this method are 1.5 to 3.5 %, an improvement over alpha spectrometry measurement methods. Model ages of five uranium standard reference materials are presented; all standards have concordant 235U-231Pa and 234U-230Th model ages.

  20. Using age of colonizing douglas-fir for the dating of young geomorphic surfaces: a case study

    USGS Publications Warehouse

    Pierson, Thomas C.

    2013-01-01

    Dating of many types of young (<500 year), dynamic, geomorphic landforms (e.g. mass-movement erosional tracks and deposits, alluvial terraces, flood plains, etc.) for purposes of hazard assessment and mitigation commonly requires greater dating precision than is available through radiocarbon dating or other methods. Ages of trees growing on landform surfaces have been used in a number of studies to estimate the time of landform creation or surface clearing, but the time lag between surface formation or disturbance and the reestablishment of trees can vary from 1 to more than 200 years (Desloges and Ryder 1990; Frenzen et al. 1988, 2005; Larsen and Bliss 1998; McCarthy and Luckman 1993; Sigafoos and Hendricks 1969; Winter et al. 2002). Appropriate lag times for selected tree species and for particular climatic and altitudinal ranges must be determined for the method to be useful.

  1. Parent-reported differences between school-aged girls and boys on the autism spectrum.

    PubMed

    Sutherland, Rebecca; Hodge, Antoinette; Bruck, Susan; Costley, Debra; Klieve, Helen

    2017-03-01

    More boys than girls are diagnosed with autism spectrum disorder; however, there are conflicting findings about whether they differ in their presentation. This study involved a survey of parents of school-aged children on the autism spectrum (171 parents of girls and 163 parents of boys) that was distributed via social media. The surveys provided insights regarding the characteristics of boys and girls (as perceived by parents) as well as some demographic information. There were very few differences reported regarding communication and social strengths and difficulties of boys and girls with autism. No differences were reported in the number of boys and girls on the autism spectrum with special interests or repetitive behaviours; however, significant differences were found in the types of special interests with boys and girls showing generally interests along traditional gender lines. Qualitative analysis of open comments indicated that some parents of girls on the autism spectrum described their daughter as trying to hide or mask her difficulties more but no parents of boys on the spectrum described this phenomenon.

  2. Age dating of shallow groundwater with chlorofluorocarbons, tritium/helium 3, and flow path analysis, southern New Jersey coastal plain

    USGS Publications Warehouse

    Szabo, Z.; Rice, D.E.; Plummer, L.N.; Busenberg, E.; Drenkard, S.; Schlosser, P.

    1996-01-01

    Groundwater age dating through the combination of transient tracer methods (chlorofluorocarbons (CFCs) and tritium/helium 3 (3H/3He)) and groundwater flow path analysis is useful for investigating groundwater travel times, flow patterns, and recharge rates, as demonstrated by this study of the homogeneous shallow, unconfined Kirkwood-Cohansey aquifer system in the southern New Jersey coastal plain. Water samples for age dating were collected from three sets of nested observation wells (10 wells) with 1.5-m-long screens located near groundwater divides. Three steady state finite difference groundwater flow models were calibrated by adjusting horizontal and vertical hydraulic conductivities to match measured heads and head differences (range, 0.002-0.23 m) among the nested wells, with a uniform recharge rate of 0.46 m per year and porosities of 0.35 (sand) and 0.45 (silt) that were assumed constant for all model simulations and travel time calculations. The simulated groundwater travel times increase with depth in the aquifer, ranging from about 1.5 to 6.5 years for the shallow wells (screen bottoms 3-4 m below the water table), from about 10 to 25 years for the medium-depth wells (screen bottoms 8-19 m below the water table), and from about 30 to more than 40 years for the deep wells (screen bottoms 24-26 m below the water table). Apparent groundwater ages based on CFC- and 3H/3He-dating techniques and model-based travel times could not be statistically differentiated, and all were strongly correlated with depth. Confinement of 3He was high because of the rapid vertical flow velocity (of the order of 1 m/yr), resulting in clear delineation of groundwater travel times based on the 3H/3He-dating technique. The correspondence between the 3H/3He and CFC ages indicates that dispersion has had a minimal effect on the tracer-based ages of water in this aquifer. Differences between the tracer-based apparent ages for seven of the 10 samples were smaller than the error values

  3. Dating young geomorphic surfaces using age of colonizing Douglas fir in southwestern Washington and northwestern Oregon, USA

    USGS Publications Warehouse

    Pierson, T.C.

    2007-01-01

    Dating of dynamic, young (<500 years) geomorphic landforms, particularly volcanofluvial features, requires higher precision than is possible with radiocarbon dating. Minimum ages of recently created landforms have long been obtained from tree-ring ages of the oldest trees growing on new surfaces. But to estimate the year of landform creation requires that two time corrections be added to tree ages obtained from increment cores: (1) the time interval between stabilization of the new landform surface and germination of the sampled trees (germination lag time or GLT); and (2) the interval between seedling germination and growth to sampling height, if the trees are not cored at ground level. The sum of these two time intervals is the colonization time gap (CTG). Such time corrections have been needed for more precise dating of terraces and floodplains in lowland river valleys in the Cascade Range, where significant eruption-induced lateral shifting and vertical aggradation of channels can occur over years to decades, and where timing of such geomorphic changes can be critical to emergency planning. Earliest colonizing Douglas fir (Pseudotsuga menziesii) were sampled for tree-ring dating at eight sites on lowland (<750 m a.s.l.), recently formed surfaces of known age near three Cascade volcanoes - Mount Rainier, Mount St. Helens and Mount Hood - in southwestern Washington and northwestern Oregon. Increment cores or stem sections were taken at breast height and, where possible, at ground level from the largest, oldest-looking trees at each study site. At least ten trees were sampled at each site unless the total of early colonizers was less. Results indicate that a correction of four years should be used for GLT and 10 years for CTG if the single largest (and presumed oldest) Douglas fir growing on a surface of unknown age is sampled. This approach would have a potential error of up to 20 years. Error can be reduced by sampling the five largest Douglas fir instead of the

  4. Dating the end of the Greek Bronze Age: a robust radiocarbon-based chronology from Assiros Toumba.

    PubMed

    Wardle, Kenneth; Higham, Thomas; Kromer, Bernd

    2014-01-01

    Over 60 recent analyses of animal bones, plant remains, and building timbers from Assiros in northern Greece form an unique series from the 14th to the 10th century BC. With the exception of Thera, the number of 14C determinations from other Late Bronze Age sites in Greece has been small and their contribution to chronologies minimal. The absolute dates determined for Assiros through Bayesian modelling are both consistent and unexpected, since they are systematically earlier than the conventional chronologies of southern Greece by between 70 and 100 years. They have not been skewed by reference to assumed historical dates used as priors. They support high rather than low Iron Age chronologies from Spain to Israel where the merits of each are fiercely debated but remain unresolved.

  5. Dating the End of the Greek Bronze Age: A Robust Radiocarbon-Based Chronology from Assiros Toumba

    PubMed Central

    Wardle, Kenneth; Higham, Thomas; Kromer, Bernd

    2014-01-01

    Over 60 recent analyses of animal bones, plant remains, and building timbers from Assiros in northern Greece form an unique series from the 14th to the 10th century BC. With the exception of Thera, the number of 14C determinations from other Late Bronze Age sites in Greece has been small and their contribution to chronologies minimal. The absolute dates determined for Assiros through Bayesian modelling are both consistent and unexpected, since they are systematically earlier than the conventional chronologies of southern Greece by between 70 and 100 years. They have not been skewed by reference to assumed historical dates used as priors. They support high rather than low Iron Age chronologies from Spain to Israel where the merits of each are fiercely debated but remain unresolved. PMID:25222862

  6. AgeFinder”: A Mac OS X computer program to evaluate electron microprobe data of monazite for chemical age dating

    NASA Astrophysics Data System (ADS)

    Appel, Peter

    2010-04-01

    A computer program is presented that can be used to obtain ages of geological significance from compositional data of monazite. The program calculates dates and their errors from U, Th and Pb concentration data obtained with the electron microprobe. The results can be displayed in isochron and gauss curve diagrams. Subsets of the data can be selected and interactively evaluated with a user friendly graphical interface. For each selected data set a cumulative date, an isochron date, their errors and the mean squared weighted deviates (MSWD) are calculated and a chi-square test is performed. The diagrams can be saved to pdf and all calculated data can be exported to a text file or saved in native format. The software runs on any Apple Macintosh with Mac OS X Tiger or later versions.

  7. Mississippi Valley-type lead-zinc deposits through geological time: Implications from recent age-dating research

    USGS Publications Warehouse

    Leach, D.L.; Bradley, D.; Lewchuk, Michael T.; Symons, David T. A.; De Marsily, G.; Brannon, J.

    2001-01-01

    Remarkable advances in age dating Mississippi Valley-type (MVT) lead-zinc deposits provide a new opportunity to understand how and where these deposits form in the Earth's crust. These dates are summarized and examined in a framework of global tectonics, paleogeography, fluid migration, and paleoclimate. Nineteen districts have been dated by paleomagnetic and/or radiometric methods. Of the districts that have both paleomagnetic and radiometric dates, only the Pine Point and East Tennessee districts have significant disagreements. This broad agreement between paleomagnetic and radiometric dates provides added confidence in the dating techniques used. The new dates confirm the direct connection between the genesis of MVT lead-zinc ores with global-scale tectonic events. The dates show that MVT deposits formed mainly during large contractional tectonic events at restricted times in the history of the Earth. Only the deposits in the Lennard Shelf of Australia and Nanisivik in Canada have dates that correspond to extensional tectonic events. The most important period for MVT genesis was the Devonian to Permian time, which corresponds to a series of intense tectonic events during the assimilation of Pangea. The second most important period for MVT genesis was Cretaceous to Tertiary time when microplate assimilation affected the western margin of North America and Africa-Eurasia. There is a notable paucity of MVT lead-zinc ore formation following the breakup of Rodinia and Pangea. Of the five MVT deposits hosted in Proterozoic rocks, only the Nanisivik deposit has been dated as Proterozoic. The contrast in abundance between SEDEX and MVT lead-zinc deposits in the Proterozoic questions the frequently suggested notion that the two types of ores share similar genetic paths. The ages of MVT deposits, when viewed with respect to the orogenic cycle in the adjacent orogen suggest that no single hydrologic model can be universally applied to the migration of the ore fluids

  8. Age calibration of weathering fractures in desert clasts: A new approach to dating geomorphic surfaces in arid landscapes

    NASA Astrophysics Data System (ADS)

    D'Arcy, Mitch; Roda Boluda, Duna; Whittaker, Alex

    2014-05-01

    Advances in geomorphological and sedimentological research depend on the availability of reliable exposure age constraints. Establishing robust age models at a high spatial and temporal resolution is crucial for measuring rates of geomorphological change and decoding complex landscapes shaped by time-dependent forces, e.g. climate fluctuations. A number of isotopic and luminescence techniques are now available for dating geomorphic surfaces, however they remain expensive and time-consuming to deploy with detailed coverage over space and time in many study areas. For this reason, quick and accessible methods for correlating and extrapolating these chronologies are needed. In arid landscapes, among others, a variety of weathering-induced changes occur to geomorphic and sedimentary surfaces, and many of these processes occur at predictable rates and can be quantified using objective, field based measurements. One example is the gradual widening of fractures that exist within boulders on desert surfaces, by a combination of processes including salt weathering and freeze-thaw cycles. The recent emergence of very detailed exposure age models in a number of locations means it is now possible to measure the rates of desert weathering processes, and use them as fully calibrated age indicators themselves. With the potential to significantly extend the coverage of existing age constraints, this kind of quantitative age correlation would enable a broad range of geomorphological and sedimentological research that depends on detailed absolute age models. We have measured the mean widths of hundreds of vertical fractures that dissect granitic boulders, on a variety of alluvial surfaces in Owens Valley, California, which have themselves been independently dated in detail using cosmogenic nuclides. Our data demonstrates for the first time that these fractures widen at a predictable, steady rate of approximately 1 mm ka-1 for at least the last 150 ka, in this arid study area in the

  9. A new Application of Ar-40/Ar-39 Dating: A Provenance Study of Middle Stone Age Obsidian Tools from Ethiopia

    NASA Astrophysics Data System (ADS)

    Nomade, S.; Vogel, N.; Renne, P. R.; Negash, A.

    2004-12-01

    The identification and geographic origin of potential sources for obsidian tools manufactured by MSA (Middle Stone Age) hominid groups is important to reconstruct source utilization and trade routes. Obsidian sourcing is done by geochemical investigation of obsidian artifacts and potential source materials and the identification of possible matches between them [e.g., 1]. Due to uncertainties arising, e.g., from intrasource inhomogeneities [2] additional methods are desirable. As a part of a pilot study, we dated by Ar-40/Ar-39 stepwise heating numerous debitage pieces of obsidian artifacts from an MSA excavation site and several potential source rock samples from a nearby obsidian outcrop in the Gademotta-Kulkuletti area near Ziway lake, Ethiopia. The ages were used, along with chemical data, to trace possible source rocks used to manufacture the artifacts. Most of the debitage samples show ages around 1.29 Ma and exhibit flat, well behaved spectra. Less well behaved spectra are obtained for two debitage samples with ages of about 1.26 Ma, and two with ages of about 0.62 Ma. We point out that despite this significant spread in the ages found, all debitage samples as well as the potential source rocks show homogeneous major and trace elemental compositions generally indicating a positive match in archeological sourcing. The ages of two potential source rocks are about 1.26 and 0.87 Ma. Thus, while there is a match with the two debitage pieces dated at 1.26 Ma, the exact outcrop of the major source for the 1.29 Ma old artifacts has not been identified yet. A second set of samples with further possible source materials for the Kulkuletti artifacts as well as another potential debitage-source material pair from a second excavation site in the Ziway lake area, Porc Epic, are currently being dated and will be presented at the conference. Already this first set of data shows not only the general applicability of Ar-40/Ar-39 dating to archeological obsidian sourcing, but

  10. Cross-checking groundwater age by 4He and 14C dating in a granite, Tono area, central Japan

    NASA Astrophysics Data System (ADS)

    Hasegawa, Takuma; Nakata, Kotaro; Tomioka, Yuichi; Goto, Kazuyuki; Kashiwaya, Koki; Hama, Katsuhiro; Iwatsuki, Teruki; Kunimaru, Takanori; Takeda, Masaki

    2016-11-01

    Groundwater dating was performed simultaneously by the 4He and 14C methods in granite of the Tono area in central Japan. Groundwater was sampled at 30 packed-off sections of six 1000-m boreholes. 4He concentrations increased and 14C concentrations decreased along a groundwater flow path on a topographic gradient. 4He ages were calculated by using the in situ 4He production rate derived from the porosity, density, and U and Th content of the rock, neglecting external flux. 14C ages were calculated with a noncorrected model in which the initial 14C content was 100 percent of the modern radiocarbon level (Co = 100 pmC), a statistical model using the average 14C content of tritium-bearing samples (Co = 46.4 pmC), and a δ13C model based on the isotopic mass balance. Although the absolute 14C ages calculated by the models were different, the relative 14C ages were almost identical. The relative 14C ages were considered reliable because dissolved inorganic carbon has no significant geochemical reactions in granite. The relation between the 4He ages and the noncorrected 14C ages was [4He age] = 1.15 [14C age] + 7200 (R2 = 0.81), except in the discharge area. The slope of this relation was equivalent to unity, which indicates that the 4He accumulation rate is confirmed by the relative 14C ages. Moreover, the accumulated 3He/4He ratio was equivalent to that derived from the 6Li(α,n)3H reaction in granite. These results show that the accumulated He is of crustal origin, produced in situ without external flux, except in the discharge area. The intercept value of 7200 a implies that the 14C concentrations were diluted due to geochemical reactions. Tritium-bearing samples supported this result. Simultaneous measurements make it feasible to estimate the accumulation rate of 4He and initial dilution of 14C, which cannot be done with a single method. Cross-checking groundwater dating has the potential to provide more reliable groundwater ages. The circulation time of the

  11. Age assessment and implications of late Quaternary periglacial and paraglacial landforms on Muckish Mountain, northwest Ireland, based on Schmidt-hammer exposure-age dating (SHD)

    NASA Astrophysics Data System (ADS)

    Wilson, Peter; Matthews, John A.

    2016-10-01

    Schmidt-hammer exposure-age dating (SHD) was applied to a variety of late Quaternary periglacial and paraglacial landforms composed of coarse rock debris on Muckish Mountain, northwest Ireland. Landform ages were determined using a linear high-precision age-calibration curve, derived from young and old control surfaces of known age on the same rock type. The SHD ages represent maximum estimates of the time elapsed since the boulders stabilised and the landforms became inactive. Most ages are also minimum estimates for the start of landform development because older boulders are buried beneath the sampled surface boulders. Ages and 95% confidence intervals obtained for blockfield, boulder lobes and talus indicate these features were likely active during several of the early Holocene cold events evidenced in Greenland ice cores and North Atlantic sediment records. Activity ceased at different times ~ 9-7 ka BP. These landforms are the first indication of a geomorphological response to early Holocene cooling in the oceanic mountains of Ireland. Late Holocene ages, obtained for rock-slope failure run-out debris and debris cone boulders, overlap with shifts to cooler and/or wetter conditions, including the Little Ice Age. Geomorphological impacts associated with these changes in climate have not previously been recorded in the Irish uplands. The SHD results indicate that previously implied timings for the stabilisation of some accumulations of coarse rock debris on mountain slopes are in need of revision.

  12. Spatial gradients in Clovis-age radiocarbon dates across North America suggest rapid colonization from the north.

    PubMed

    Hamilton, Marcus J; Buchanan, Briggs

    2007-10-02

    A key issue in the debate over the initial colonization of North America is whether there are spatial gradients in the distribution of the Clovis-age occupations across the continent. Such gradients would help indicate the timing, speed, and direction of the colonization process. In their recent reanalysis of Clovis-age radiocarbon dates, Waters and Stafford [Waters MR, Stafford TW, Jr (2007) Science 315:1122-1126] report that they find no spatial patterning. Furthermore, they suggest that the brevity of the Clovis time period indicates that the Clovis culture represents the diffusion of a technology across a preexisting pre-Clovis population rather than a population expansion. In this article, we focus on two questions. First, we ask whether there is spatial patterning to the timing of Clovis-age occupations and, second, whether the observed speed of colonization is consistent with demic processes. With time-delayed wave-of-advance models, we use the radiocarbon record to test several alternative colonization hypotheses. We find clear spatial gradients in the distribution of these dates across North America, which indicate a rapid wave of advance originating from the north. We show that the high velocity of this wave can be accounted for by a combination of demographic processes, habitat preferences, and mobility biases across complex landscapes. Our results suggest that the Clovis-age archaeological record represents a rapid demic colonization event originating from the north.

  13. Spatial gradients in Clovis-age radiocarbon dates across North America suggest rapid colonization from the north

    PubMed Central

    Hamilton, Marcus J.; Buchanan, Briggs

    2007-01-01

    A key issue in the debate over the initial colonization of North America is whether there are spatial gradients in the distribution of the Clovis-age occupations across the continent. Such gradients would help indicate the timing, speed, and direction of the colonization process. In their recent reanalysis of Clovis-age radiocarbon dates, Waters and Stafford [Waters MR, Stafford TW, Jr (2007) Science 315:1122–1126] report that they find no spatial patterning. Furthermore, they suggest that the brevity of the Clovis time period indicates that the Clovis culture represents the diffusion of a technology across a preexisting pre-Clovis population rather than a population expansion. In this article, we focus on two questions. First, we ask whether there is spatial patterning to the timing of Clovis-age occupations and, second, whether the observed speed of colonization is consistent with demic processes. With time-delayed wave-of-advance models, we use the radiocarbon record to test several alternative colonization hypotheses. We find clear spatial gradients in the distribution of these dates across North America, which indicate a rapid wave of advance originating from the north. We show that the high velocity of this wave can be accounted for by a combination of demographic processes, habitat preferences, and mobility biases across complex landscapes. Our results suggest that the Clovis-age archaeological record represents a rapid demic colonization event originating from the north. PMID:17898176

  14. Himalaya evolution at Paleogene-Neogene boundary unraveled by zircon age spectrum from Arabian Sea Sediments

    NASA Astrophysics Data System (ADS)

    Feng, Han; Lu, Huayu; Zhang, Hanzhi

    2016-04-01

    Although virtually all the intensive orogenic activities of Himalaya occurred in Neogene, the tectonic evolution of this high mountain range in Paleogene is poorly understood. Investigations of tectonic change pattern at Paleogene-Neogene boundary are important to better understand the interaction between mountain building and climate evolution. Here we present new U-Pb ages of zircon grains from Indus Fan sediments to constrain the orogenic history of Himalaya at Paleogene-Neogene boundary. 11 samples between late Oligocene and early Miocene from ODP 117 cores are dated by the zircon U-Pb technique. We calculate relative contributions of potential sources by counting zircon grains for each sample, and the quantized results indicate Himalaya contributed sediments to the coring site, and an extremely high input from Great and Tethyan Himalaya during late Oligocene-early Miocene. Four samples in Pleistocene are also dated for comparison, which indicates that high proportion of Lesser Himalaya has contributed to the sediment in Pleistocene. Our results suggest that the high contribution of Great and Tethyan Himalaya at Paleogene-Neogene boundary might correlate with the beginning of activity of MCT and extension of STD with leucogranite intrusion along Himalaya, which give rise to the extensive Great Himalaya exhumation. Our study demonstrates that zircon U-Pb dating technique is a good tool to reconstruct erosional history of mountain building on a tectonic timescale. Key words: ODP, Himalaya, Indus Fan, zircon U-Pb dating, Paleogene-Neogene boundary

  15. Towards an absolute chronology for the Aegean iron age: new radiocarbon dates from Lefkandi, Kalapodi and Corinth.

    PubMed

    Toffolo, Michael B; Fantalkin, Alexander; Lemos, Irene S; Felsch, Rainer C S; Niemeier, Wolf-Dietrich; Sanders, Guy D R; Finkelstein, Israel; Boaretto, Elisabetta

    2013-01-01

    The relative chronology of the Aegean Iron Age is robust. It is based on minute stylistic changes in the Submycenaean, Protogeometric and Geometric styles and their sub-phases. Yet, the absolute chronology of the time-span between the final stages of Late Helladic IIIC in the late second millennium BCE and the archaic colonization of Italy and Sicily toward the end of the 8(th) century BCE lacks archaeological contexts that can be directly related to events carrying absolute dates mentioned in Egyptian/Near Eastern historical sources, or to well-dated Egyptian/Near Eastern rulers. The small number of radiocarbon dates available for this time span is not sufficient to establish an absolute chronological sequence. Here we present a new set of short-lived radiocarbon dates from the sites of Lefkandi, Kalapodi and Corinth in Greece. We focus on the crucial transition from the Submycenaean to the Protogeometric periods. This transition is placed in the late 11(th) century BCE according to the Conventional Aegean Chronology and in the late 12(th) century BCE according to the High Aegean Chronology. Our results place it in the second half of the 11(th) century BCE.

  16. Towards an Absolute Chronology for the Aegean Iron Age: New Radiocarbon Dates from Lefkandi, Kalapodi and Corinth

    PubMed Central

    Toffolo, Michael B.; Fantalkin, Alexander; Lemos, Irene S.; Felsch, Rainer C. S.; Niemeier, Wolf-Dietrich; Sanders, Guy D. R.; Finkelstein, Israel; Boaretto, Elisabetta

    2013-01-01

    The relative chronology of the Aegean Iron Age is robust. It is based on minute stylistic changes in the Submycenaean, Protogeometric and Geometric styles and their sub-phases. Yet, the absolute chronology of the time-span between the final stages of Late Helladic IIIC in the late second millennium BCE and the archaic colonization of Italy and Sicily toward the end of the 8th century BCE lacks archaeological contexts that can be directly related to events carrying absolute dates mentioned in Egyptian/Near Eastern historical sources, or to well-dated Egyptian/Near Eastern rulers. The small number of radiocarbon dates available for this time span is not sufficient to establish an absolute chronological sequence. Here we present a new set of short-lived radiocarbon dates from the sites of Lefkandi, Kalapodi and Corinth in Greece. We focus on the crucial transition from the Submycenaean to the Protogeometric periods. This transition is placed in the late 11th century BCE according to the Conventional Aegean Chronology and in the late 12th century BCE according to the High Aegean Chronology. Our results place it in the second half of the 11th century BCE. PMID:24386150

  17. A new U/Pb date for the basal Meishucun section and implications for the age of the Cambrian explosion

    NASA Astrophysics Data System (ADS)

    Brooks, B. J.; Crowley, J. L.; Bowring, S. A.; Cervato, C.; Jin, Y.

    2006-12-01

    The Early Cambrian of southern China has long been recognized to record the spectacular transition from microscopic small shelly fossils to a fauna characterized by large, diverse higher bilaterians during part of the Early Cambrian evolutionary explosion. Understanding the timing and rate of this evolutionary transition has been aided through the integration of U/Pb geochronology into Cambrian fossil biozones, which has established strong tie-points between platforms. The Meishucun section (Yunnan, China) is one of the units that best preserves what could be considered the prelude to the Cambrian explosion. Several attempts at dating volcanic horizons within this section have resulted in U/Pb zircon dates that range from 538 to 525 Ma, making correlations to sections further afield problematic. This new high-precision U/Pb date of 533 Ma for Meishucun's Bed 5 is in broad agreement but considerably more precise than previous U/Pb ages. This indicates that the low diversity fauna of the Anabarites trisulcatus--Protohertzina anabarica zone persisted for no less than the first 9 m.y. of the Cambrian in China, and sets an additional lower bracket age for the emergence of higher bilaterians (e.g. trilobites, soft-bodied fauna).

  18. The Couple Who Facebooks Together, Stays Together: Facebook Self-Presentation and Relationship Longevity Among College-Aged Dating Couples.

    PubMed

    Toma, Catalina L; Choi, Mina

    2015-07-01

    Drawing on public commitment theory, this research examined the association between Facebook self-presentations of coupledom and relationship longevity among college-aged dating partners. Using a longitudinal design and a path model analytic approach, this study shows that Facebook self-presentational cues (i.e., being listed as "in a relationship," posting dyadic photographs, writing on the partner's wall) were associated with an increase in relationship commitment for dating couples, which, in turn, increased their likelihood of remaining together after 6 months. Contrary to predictions, the number of mutual Friends and the number of posts written by partners on participants' walls were negatively related to relationship commitment. This study is the first to apply public commitment theory to an online romantic relationship context, and one of the few to examine the effects of Facebook on the state and fate of romantic relationships.

  19. Initial excavation and dating of Ngalue Cave: a Middle Stone Age site along the Niassa Rift, Mozambique.

    PubMed

    Mercader, Julio; Asmerom, Yemane; Bennett, Tim; Raja, Mussa; Skinner, Anne

    2009-07-01

    Direct evidence for a systematic occupation of the African tropics during the early late Pleistocene is lacking. Here, we report a record of human occupation between 105-42ka, based on results from a radiometrically-dated cave section from the Mozambican segment of the Niassa (Malawi/Nyasa) Rift called Ngalue. The sedimentary sequence from bottom to top has five units. We concentrate on the so-called "Middle Beds," which contain a Middle Stone Age industry characterized by the use of the discoidal reduction technique. A significant typological feature is the presence of formal types such as points, scrapers, awls, and microliths. Special objects consist of grinders/core-axes covered by ochre. Ngalue is one of the few directly-dated Pleistocene sites located along the biogeographical corridor for modern human dispersals that links east, central, and southern Africa, and, with further study, may shed new light on hominin cave habitats during the late Pleistocene.

  20. Age-related abnormalities in white matter microstructure in autism spectrum disorders

    PubMed Central

    Kleinhans, Natalia M.; Pauley, Gregory; Richards, Todd; Neuhaus, Emily; Martin, Nathalie; Corrigan, Neva M.; Shaw, Dennis W.; Estes, Annette; Dager, Stephen R.

    2012-01-01

    Abnormalities in structural and functional connectivity have been reported in autism spectrum disorders (ASD) across a wide age range. However, developmental changes in white matter microstructure are poorly understood. We used a cross-sectional design to determine whether white matter abnormalities measured using diffusion tensor imaging (DTI) were present in adolescents and adults with ASD and whether age-related changes in white matter microstructure differed between ASD and typically developing (TD) individuals. Participants included 28 individuals with ASD and 33 TD controls matched on age and IQ and assessed at one time point. Widespread decreased fractional anisotropy (FA), and increased radial diffusivity (RaD) and mean diffusivity (MD) were observed in the ASD group compared to the TD group. In addition, significant group-by-age interactions were also observed in FA, RaD, and MD in all major tracts except the brain stem, indicating that age-related changes in white matter microstructure differed between the groups. We propose that white matter microstructural changes in ASD may reflect myelination and/or other structural differences including differences in axonal density/arborization. In addition, we suggest that white matter microstuctural impairments may be normalizing during young adulthood in ASD. Future longitudinal studies that include a wider range of ages and more extensive clinical characterization will be critical for further uncovering the neurodevelopmental processes unfolding during this dynamic time in development. PMID:22902768

  1. 40Ar/39Ar dating of Pleistocene tuffs: an accurate age for the Matuyama-Brunhes geomagnetic reversal (MBGR)

    NASA Astrophysics Data System (ADS)

    Mark, D. F.; Renne, P. R.; Morgan, L. E.; Deino, A.; Smith, V. C.; Ellis, B. S.; Pearce, N. J.

    2012-12-01

    Recent recalibrations of the 40Ar/39Ar system [1,2] reveal inconsistencies with some previous ages inferred for the MBGR. An Ar/Ar age [3] for the Bishop Tuff (BT) (which post-dates the MBGR by at least 15.3 ± 2.2 ka [3]) recalculated [2] yields an age of 778.0 ± 3.8 ka (1σ, full systematic uncertainty). The age is c. 10 ka older than the BT zircon ID-TIMS U-Pb age [4] and places the MBGR at c. 793 ka, c. 13 and 20 ka older than astronomical ages for the MBGR of 780 ka [5] and 773 ka [6], respectively. To determine an accurate age for the MBGR, we have made a series of 40Ar/39Ar age determinations for Pleistocene tuffs from both Indonesia and North America that have direct relationships to the MBGR. Blind analyses were conducted at SUERC and BGC. We observed excellent inter-laboratory agreement and no systematic offset in data. Ar/Ar ages are reported relative to [2] (1σ, full systematic uncertainty). Drill cores from ODP Site 758 show the precise location of the MBGR. Below the MBGR are two distal tephra horizons that we have identified as products of two temporally distinct Old Toba Tuff (OTT) eruptions (layer d OTT1 and layer D OTT2). Continuous sedimentation between OTT1 (802.8 ± 0.7 ka, n = 100, MSWD 1.2) and OTT2 (796.2 ± 0.8 ka, n = 62, MSWD 1.3) allows for calculation of an accurate sedimentation rate and for extrapolation of an age from OTT2 to the MBGR. Data define an age for the MBGR of 795.2 ± 0.9 ka. Using tephra above the MBGR boundary, the Middle Toba Tuff (layer C) and Young Toba Tuff (layer A), extrapolation down core supports a MBGR age of c. 795 ka. Recent age data for BT sanidine reported relative to FCs at 28.172 Ma (767.4 ± 1.1 Ma) [7] oddly yielded an Ar/Ar age that was indistinguishable from the BT zircon U-Pb age [4], which is consistent with previous 40Ar/39Ar age measurements made relative to FCs at 28.02 Ma [3]. Thus we made a series of 40Ar/39Ar measurements on the exact same sample as used by Rivera et al. [7] and observed

  2. Trajectories Leading to Autism Spectrum Disorders Are Affected by Paternal Age: Findings from Two Nationally Representative Twin Studies

    ERIC Educational Resources Information Center

    Lundstrom, Sebastian; Haworth, Claire M. A.; Carlstrom, Eva; Gillberg, Christopher; Mill, Jonathan; Rastam, Maria; Hultman, Christina M.; Ronald, Angelica; Anckarsater, Henrik; Plomin, Robert; Lichtenstein, Paul; Reichenberg, Abraham

    2010-01-01

    Background: Despite extensive efforts, the causes of autism remain unknown. Advancing paternal age has been associated with various neurodevelopmental disorders. We aim to investigate three unresolved questions: (a) What is the association between paternal age and autism spectrum disorders (ASD)?; (b) Does paternal age moderate the genetic and…

  3. Precise Surface Exposure Dating of Early Holocene and Little Ice Age Moraines in the Cordillera Vilcabamba of Southern Peru

    NASA Astrophysics Data System (ADS)

    Licciardi, J. M.; Schaefer, J. M.; Lund, D. C.; Taggart, J. R.

    2008-12-01

    We have established precise ages of two glacial events in the tropical Andean highlands of southern Peru. The field site is located on the flanks of Nevado Salcantay (6271 m asl; 13°20'S latitude), the highest peak in the Cordillera Vilcabamba. A two-fold sequence of nested lateral and end moraines was mapped in a glacial trough emanating from the south face of Salcantay. Well-defined outer and inner moraines were deposited by valley glaciers that terminated 5 km and 3 km, respectively, from their head on the Salcantay massif. Cosmogenic 10Be surface exposure dating of boulders on the outer (n = 7) and inner (n = 7) moraine crests expands upon initial age control for these deposits and improves substantially on the precision of earlier 10Be measurements. The new results yield mean ages of 9.0 ± 0.3 ka for the outer moraine and 195 ± 24 years for the inner moraine, corresponding to glacial events during the early and latest Holocene. These ages are derived using the CRONUS-Earth 10Be exposure age calculator with Lal-Stone production rate scaling and the default height-pressure relationship. The inner moraine age correlates with the timing of the Little Ice Age as defined from northern mid- and high latitude records, and indicates considerable expansion of glaciers heading on Nevado Salcantay during this climatic minimum. Recent geomorphic mapping has identified similar sequences of moraines in adjacent drainages on and near Salcantay, suggesting a broader regional signal of two prominent Holocene glacial events in this segment of the southern Peruvian Andes; 10Be dating of these additional moraines is underway. Our new glacier chronologies complement ice core and lacustrine paleoclimate records in the vicinity, thereby increasing spatial and temporal coverage for identifying patterns of climate change in the tropical Andes during the Holocene. Apart from their paleoclimatic significance, the results also demonstrate a newly- developed capability of 10Be exposure

  4. The effects of aging on the BTBR mouse model of autism spectrum disorder

    PubMed Central

    Jasien, Joan M.; Daimon, Caitlin M.; Wang, Rui; Shapiro, Bruce K.; Martin, Bronwen; Maudsley, Stuart

    2014-01-01

    Autism spectrum disorder (ASD) is a complex heterogeneous neurodevelopmental disorder characterized by alterations in social functioning, communicative abilities, and engagement in repetitive or restrictive behaviors. The process of aging in individuals with autism and related neurodevelopmental disorders is not well understood, despite the fact that the number of individuals with ASD aged 65 and older is projected to increase by over half a million individuals in the next 20 years. To elucidate the effects of aging in the context of a modified central nervous system, we investigated the effects of age on the BTBR T + tf/j mouse, a well characterized and widely used mouse model that displays an ASD-like phenotype. We found that a reduction in social behavior persists into old age in male BTBR T + tf/j mice. We employed quantitative proteomics to discover potential alterations in signaling systems that could regulate aging in the BTBR mice. Unbiased proteomic analysis of hippocampal and cortical tissue of BTBR mice compared to age-matched wild-type controls revealed a significant decrease in brain derived neurotrophic factor and significant increases in multiple synaptic markers (spinophilin, Synapsin I, PSD 95, NeuN), as well as distinct changes in functional pathways related to these proteins, including “Neural synaptic plasticity regulation” and “Neurotransmitter secretion regulation.” Taken together, these results contribute to our understanding of the effects of aging on an ASD-like mouse model in regards to both behavior and protein alterations, though additional studies are needed to fully understand the complex interplay underlying aging in mouse models displaying an ASD-like phenotype. PMID:25225482

  5. 17 CFR 210.3-12 - Age of financial statements at effective date of registration statement or at mailing date of...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... balance sheet as of an interim date within the number of days specified in paragraph (g) of this section... fiscal year and the date of the interim balance sheet provided and for the corresponding period of the... interim financial statements shall be at least as current as the most recent financial statements...

  6. Protolith age of Santa Maria Chico granulites dated on zircons from an associated amphibolite-facies granodiorite in southernmost Brazil.

    PubMed

    Hartmann, Léo A; Liu, Dunyi; Wang, Yenbin; Massonne, Hans-Joachim; Santos, João O S

    2008-09-01

    U-Pb dating of zircon was undertaken with the Beijing SHRIMP II (sensitive high resolution ion microprobe) on anamphibolite facies granodiorite and an almandine-albite granulite from the Santa Maria Chico Granulitic Complex, southern Brazilian Shield. This work was also done to unravel protolith ages which are often hidden in the array of partly reset data. The obtained metamorphic ages of the granodiorite gneiss and the granulite are 2035 +/- 9 Ma and 2006 +/- 3 Ma, respectively. These data are within the range of metamorphic ages determined in previous studies (2022 +/- 18 Ma and 2031 +/- 40 Ma). However, protolith ages for the granodiorite (2366 +/- 8 Ma) and the granulite (2489 +/- 6 Ma) were obtained which are outside the previously recognized range (> 2510-2555 Ma). The magmatic protolith age of the granodiorite refers to a previously little known magmatic event in the shield. Further investigations may demonstrate that amphibolite facies zircon crystals are useful as a window into geological events in associated granulites, because zircon ages are blurred in the studied granulites.

  7. New ages for Middle and Later Stone Age deposits at Mumba rockshelter, Tanzania: optically stimulated luminescence dating of quartz and feldspar grains.

    PubMed

    Gliganic, Luke A; Jacobs, Zenobia; Roberts, Richard G; Domínguez-Rodrigo, Manuel; Mabulla, Audax Z P

    2012-04-01

    The archaeological deposits at Mumba rockshelter, northern Tanzania, have been excavated for more than 70 years, starting with Margit and Ludwig Köhl-Larsen in the 1930s. The assemblages of Middle Stone Age (MSA) and Later Stone Age (LSA) artefacts collected from this site constitute the type sequences for these cultural phases in East Africa. Despite its archaeological importance, however, the chronology of the site is poorly constrained, despite the application since the 1980s of several dating methods (radiocarbon, uranium-series and amino acid racemisation) to a variety of materials recovered from the deposits. Here, we review these previous chronologies for Mumba and report new ages obtained from optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) measurements on single grains of quartz and multi-grain aliquots of potassium (K) feldspar from the MSA and LSA deposits. Measurements of single grains of quartz allowed the rejection of unrepresentative grains and the application of appropriate statistical models to obtain the most reliable age estimates, while measurements of K-feldspars allowed the chronology to be extended to older deposits. The seven quartz ages and four K-feldspar ages provide improved temporal constraints on the archaeological sequence at Mumba. The deposits associated with the latest Kisele Industry (Bed VI-A) and the earliest Mumba Industry (Bed V) are dated to 63.4 ± 5.7 and 56.9 ± 4.8 ka (thousands of years ago), respectively, thus constraining the time of transition between these two archaeological phases to ~60 ka. An age of 49.1 ± 4.3 ka has been obtained for the latest deposits associated with the Mumba Industry, which show no evidence for post-depositional mixing and contain ostrich eggshell (OES) beads and abundant microlithics. The Nasera Industry deposits (Bed III) contain large quantities of OES beads and date to 36.8 ± 3.4 ka. We compare the luminescence ages with the previous chronologies for

  8. Isotopic composition analysis and age dating of uranium samples by high resolution gamma ray spectrometry

    NASA Astrophysics Data System (ADS)

    Apostol, A. I.; Pantelica, A.; Sima, O.; Fugaru, V.

    2016-09-01

    Non-destructive methods were applied to determine the isotopic composition and the time elapsed since last chemical purification of nine uranium samples. The applied methods are based on measuring gamma and X radiations of uranium samples by high resolution low energy gamma spectrometric system with planar high purity germanium detector and low background gamma spectrometric system with coaxial high purity germanium detector. The ;Multigroup γ-ray Analysis Method for Uranium; (MGAU) code was used for the precise determination of samples' isotopic composition. The age of the samples was determined from the isotopic ratio 214Bi/234U. This ratio was calculated from the analyzed spectra of each uranium sample, using relative detection efficiency. Special attention is paid to the coincidence summing corrections that have to be taken into account when performing this type of analysis. In addition, an alternative approach for the age determination using full energy peak efficiencies obtained by Monte Carlo simulations with the GESPECOR code is described.

  9. In Situ Radiometric and Exposure Age Dating of the Martian Surface

    NASA Technical Reports Server (NTRS)

    Farley, K. A.; Malespin, C.; Mahaffy, P.; Grotzinger, J. P.; Vasconcelos, P. M.; Milliken, R. E.; Malin, M.; Edgett, K. S.; Pavlov, A. A.; Hurowitz, J. A.; Grant, J. A.; Miller, H. B.; Arvidson, R.; Beegle, L.; Calef, F.; Conrad, P. G.; Dietrich, W. E.; Eigenbrode, J.; Gellert, R.; Gupta, S.; Hamilton, V.; Hassler, D. M.; Lewis, K. W.; McLennan, S. M.; Ming, D. M.; Navarro-Gonzalez, R.; Schwenzer, S. P.; Steele, A.; Stolper, E. M.; Sumner, D. Y.; Vaniman, D.; Vasavada, A.; Williford, K.; Wimmer-Schweingruber, R. F.

    2014-01-01

    We determined radiogenic and cosmogenic noble gases in a mudstone on the floor of Gale Crater. A K-Ar age of 4.21 +/- 0.35 billion years represents a mixture of detrital and authigenic components and confirms the expected antiquity of rocks comprising the crater rim. Cosmic-ray-produced 3He, 21Ne, and 36Ar yield concordant surface exposure ages of 78 T 30 million years. Surface exposure occurred mainly in the present geomorphic setting rather than during primary erosion and transport. Our observations are consistent with mudstone deposition shortly after the Gale impact or possibly in a later event of rapid erosion and deposition. The mudstone remained buried until recent exposure by wind-driven scarp retreat. Sedimentary rocks exposed by this mechanism may thus offer the best potential for organic biomarker preservation against destruction by cosmic radiation.

  10. In situ radiometric and exposure age dating of the martian surface.

    PubMed

    Farley, K A; Malespin, C; Mahaffy, P; Grotzinger, J P; Vasconcelos, P M; Milliken, R E; Malin, M; Edgett, K S; Pavlov, A A; Hurowitz, J A; Grant, J A; Miller, H B; Arvidson, R; Beegle, L; Calef, F; Conrad, P G; Dietrich, W E; Eigenbrode, J; Gellert, R; Gupta, S; Hamilton, V; Hassler, D M; Lewis, K W; McLennan, S M; Ming, D; Navarro-González, R; Schwenzer, S P; Steele, A; Stolper, E M; Sumner, D Y; Vaniman, D; Vasavada, A; Williford, K; Wimmer-Schweingruber, R F

    2014-01-24

    We determined radiogenic and cosmogenic noble gases in a mudstone on the floor of Gale Crater. A K-Ar age of 4.21 ± 0.35 billion years represents a mixture of detrital and authigenic components and confirms the expected antiquity of rocks comprising the crater rim. Cosmic-ray-produced (3)He, (21)Ne, and (36)Ar yield concordant surface exposure ages of 78 ± 30 million years. Surface exposure occurred mainly in the present geomorphic setting rather than during primary erosion and transport. Our observations are consistent with mudstone deposition shortly after the Gale impact or possibly in a later event of rapid erosion and deposition. The mudstone remained buried until recent exposure by wind-driven scarp retreat. Sedimentary rocks exposed by this mechanism may thus offer the best potential for organic biomarker preservation against destruction by cosmic radiation.

  11. Age-Dating Star Clusters in the Luminous Infrared Galaxy VV340

    NASA Astrophysics Data System (ADS)

    Yarber, Aara'L.; Evans, A. S.

    2014-01-01

    The luminous infrared galaxy (LIRG: i.e., L_IR [8-1000 microns] > 10^11 L_sun) VV 340 is observed to be a pair of z = 0.03 interacting spiral galaxies, with one being observed face-on (VV340North) and one edge-on (VV 340South). The interaction has triggered a burst of star formation in both galaxies, and we make use of Hubble Space Telescope ultraviolet (ACS/SBC) and optical (ACS/WFC) imaging data to constrain the age of luminous optical clusters in the face-on galaxy VV 340South. We find that, for an instantaneous starburst, a Salpeter IMF and no reddening, the cluster ages are in the range of 10-300 million years old. However, the clusters can be a young as a few million years with significant amounts of reddening. The upper limit cluster age range is consistent with detailed modeling of a subset of LIRGs which show that pericentric passage in many LIRGs occurred 200-500 million years prior to when these systems are being observed. This study is part of the Great Observatories All-sky LIRG Survey (GOALS), which is a multi-wavelength campaign designed, in part, to study the evolution of star formation in LIRGs.

  12. Estimating limiting age for Pleistocene erosional surfaces in central Montana by uranium-series dating of associated travertines.

    USGS Publications Warehouse

    Szabo, B. J.; Lindsey, D.A.

    1986-01-01

    Analysis of three travertine samples from the southeast side of The Park (central Montana) yield an average uranium-thorium age of 73 000 yr. Another sample from the west side of The Park is 320 000 yr old. These results indicate that travertine deposits may have formed at several intervals. The surface beneath The Park travertine is older than about 320 000 yr. Number 2 pediment gravels that contain travertine downslope from the oldest dated sample may be younger than about 320 000 yr. -Authors

  13. The AMS 14C dating of Iron Age rice chaff ceramic temper from Ban Non Wat, Thailand: First results and its interpretation

    NASA Astrophysics Data System (ADS)

    Higham, Charles F. W.; Kuzmin, Yaroslav V.; Burr, G. S.

    2010-04-01

    Pottery tempered with rice chaff from the early Iron Age cemetery of Ban Non Wat site, northeast Thailand, has been subjected to direct AMS 14C dating, using low temperature combustion with oxygen as originally developed by authors. The carbon yield (0.2-0.5%) testifies the suitability of this pottery for dating. However, not all the results are in agreement with expected archaeological ages and other 14C dates from the studied site and neighboring site of Noen U-Loke. This calls for a thorough analysis and interpretation of pottery temper dates from the region.

  14. Validation of the Pictorial Infant Communication Scale for preschool-aged children with autism spectrum disorder.

    PubMed

    Ghilain, Christine S; Parlade, Meaghan V; McBee, Matthew T; Coman, Drew C; Owen, Taylor; Gutierrez, Anibal; Boyd, Brian; Odom, Samuel; Alessandri, Michael

    2017-02-01

    Joint attention, or the shared focus of attention between objects or events and a social partner, is a crucial milestone in the development of social communication and a notable area of deficit in children with autism spectrum disorder. While valid parent-report screening measures of social communication are available, the majority of these measures are designed to assess a wide range of behaviors. Targeted assessment of joint attention and related skills is primarily limited to semi-structured, examiner-led interactions, which are time-consuming and laborious to score. The Pictorial Infant Communication Scale is an efficient parent-report measure of joint attention that can be used as a complement to structured assessments in fully characterizing early social communication development. This study examined the psychometric properties of the Pictorial Infant Communication Scale. Results revealed a high degree of internal consistency and strong intercorrelations between subscales. Additionally, confirmatory factor analysis supported a three-factor model of joint attention. Furthermore, significant correlations between the Pictorial Infant Communication Scale and direct clinical measures of child joint attention, language skills, and autism spectrum disorder symptom severity were suggestive of concurrent validity. Findings suggest that the Pictorial Infant Communication Scale is a promising tool for measuring joint attention skills in preschool-aged children with autism spectrum disorder.

  15. Hippocampal Formation Maldevelopment and Sudden Unexpected Death across the Pediatric Age Spectrum.

    PubMed

    Kinney, Hannah C; Poduri, Annapurna H; Cryan, Jane B; Haynes, Robin L; Teot, Lisa; Sleeper, Lynn A; Holm, Ingrid A; Berry, Gerald T; Prabhu, Sanjay P; Warfield, Simon K; Brownstein, Catherine; Abram, Harry S; Kruer, Michael; Kemp, Walter L; Hargitai, Beata; Gastrang, Joanne; Mena, Othon J; Haas, Elisabeth A; Dastjerdi, Roya; Armstrong, Dawna D; Goldstein, Richard D

    2016-10-01

    Sudden infant death syndrome (SIDS) and sudden unexplained death in childhood (SUDC) are defined as sudden death in a child remaining unexplained despite autopsy and death scene investigation. They are distinguished from each other by age criteria, i.e. with SIDS under 1 year and SUDC over 1 year. Our separate studies of SIDS and SUDC provide evidence of shared hippocampal abnormalities, specifically focal dentate bilamination, a lesion classically associated with temporal lobe epilepsy, across the 2 groups. In this study, we characterized the clinicopathologic features in a retrospective case series of 32 children with sudden death and hippocampal formation (HF) maldevelopment. The greatest frequency of deaths was between 3 weeks and 3 years (81%, 26/32). Dentate anomalies were found across the pediatric age spectrum, supporting a common vulnerability that defies the 1-year age cutoff between SIDS and SUDC. Twelve cases (38%) had seizures, including 7 only with febrile seizures. Subicular anomalies were found in cases over 1 year of age and were associated with increased risk of febrile seizures. Sudden death associated with HF maldevelopment reflects a complex interaction of intrinsic and extrinsic factors that lead to death at different pediatric ages, and may be analogous to sudden unexplained death in epilepsy.

  16. Phylogenomic Dating-A Method of Constraining the Age of Microbial Taxa That Lack a Conventional Fossil Record

    NASA Astrophysics Data System (ADS)

    Blank, Carrine E.

    2009-03-01

    A phylogenomic dating approach was used to identify potential age constraints for multiple archaeal groups, many of which have no fossil, isotopic, or biomarker record. First, well-resolved phylogenetic trees were inferred with the use of multiple gene sequences obtained from whole genome sequences. Next, the ability to use oxygen as a terminal electron acceptor was coded into characters, and ancestral state reconstruction was used to identify clades with taxa that metabolize oxygen and likely had an aerobic ancestor. Next, the habitat of the ancestor was inferred. If the local presence of Cyanobacteria could be excluded from the putative ancestral habitat, then these clades would have originated after the rise in atmospheric oxygen 2.32 Ga. With this method, an upper age of 2.32 Ga (an "oxygen age constraint") is proposed for four major archaeal clades: the Sulfolobales, Thermoplasmatales, Thermoproteus neutrophilus/Pyrobaculum spp., and the Thermoproteales. It was also shown that the halophilic archaea likely had an aerobic common ancestor, yet the possibility of local oxygen oases before oxygenation of the atmosphere could not be formally rejected. Thus, an oxygen age constraint was not assessed for this group. This work suggests that many archaeal groups are not as ancient as many in the research community have previously assumed, and it provides a new method for establishing upper age constraints for major microbial groups that lack a conventional fossil record.

  17. Age and Date for Early Arrival of the Acheulian in Europe (Barranc de la Boella, la Canonja, Spain)

    PubMed Central

    Vallverdú, Josep; Saladié, Palmira; Rosas, Antonio; Huguet, Rosa; Cáceres, Isabel; Mosquera, Marina; Garcia-Tabernero, Antonio; Estalrrich, Almudena; Lozano-Fernández, Iván; Pineda-Alcalá, Antonio; Carrancho, Ángel; Villalaín, Juan José; Bourlès, Didier; Braucher, Régis; Lebatard, Anne; Vilalta, Jaume; Esteban-Nadal, Montserrat; Bennàsar, Maria Lluc; Bastir, Marcus; López-Polín, Lucía; Ollé, Andreu; Vergés, Josep Maria; Ros-Montoya, Sergio; Martínez-Navarro, Bienvenido; García, Ana; Martinell, Jordi; Expósito, Isabel; Burjachs, Francesc; Agustí, Jordi; Carbonell, Eudald

    2014-01-01

    The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently considered to have occurred as short and poorly dated biological dispersions. Questions as to the tempo and mode of these early prehistoric settlements have given rise to debates concerning the taxonomic significance of the lithic assemblages, as trace fossils, and the geographical distribution of the technological traditions found in the Lower Palaeolithic record. Here, we report on the Barranc de la Boella site which has yielded a lithic assemblage dating to ∼1 million years ago that includes large cutting tools (LCT). We argue that distinct technological traditions coexisted in the Iberian archaeological repertoires of the late Early Pleistocene age in a similar way to the earliest sub-Saharan African artefact assemblages. These differences between stone tool assemblages may be attributed to the different chronologies of hominin dispersal events. The archaeological record of Barranc de la Boella completes the geographical distribution of LCT assemblages across southern Eurasia during the EMPT (Early-Middle Pleistocene Transition, circa 942 to 641 kyr). Up to now, chronology of the earliest European LCT assemblages is based on the abundant Palaeolithic record found in terrace river sequences which have been dated to the end of the EMPT and later. However, the findings at Barranc de la Boella suggest that early LCT lithic assemblages appeared in the SW of Europe during earlier hominin dispersal episodes before the definitive colonization of temperate Eurasia took place. PMID:25076416

  18. Age and date for early arrival of the Acheulian in Europe (Barranc de la Boella, la Canonja, Spain).

    PubMed

    Vallverdú, Josep; Saladié, Palmira; Rosas, Antonio; Huguet, Rosa; Cáceres, Isabel; Mosquera, Marina; Garcia-Tabernero, Antonio; Estalrrich, Almudena; Lozano-Fernández, Iván; Pineda-Alcalá, Antonio; Carrancho, Ángel; Villalaín, Juan José; Bourlès, Didier; Braucher, Régis; Lebatard, Anne; Vilalta, Jaume; Esteban-Nadal, Montserrat; Bennàsar, Maria Lluc; Bastir, Marcus; López-Polín, Lucía; Ollé, Andreu; Vergés, Josep Maria; Ros-Montoya, Sergio; Martínez-Navarro, Bienvenido; García, Ana; Martinell, Jordi; Expósito, Isabel; Burjachs, Francesc; Agustí, Jordi; Carbonell, Eudald

    2014-01-01

    The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently considered to have occurred as short and poorly dated biological dispersions. Questions as to the tempo and mode of these early prehistoric settlements have given rise to debates concerning the taxonomic significance of the lithic assemblages, as trace fossils, and the geographical distribution of the technological traditions found in the Lower Palaeolithic record. Here, we report on the Barranc de la Boella site which has yielded a lithic assemblage dating to ∼1 million years ago that includes large cutting tools (LCT). We argue that distinct technological traditions coexisted in the Iberian archaeological repertoires of the late Early Pleistocene age in a similar way to the earliest sub-Saharan African artefact assemblages. These differences between stone tool assemblages may be attributed to the different chronologies of hominin dispersal events. The archaeological record of Barranc de la Boella completes the geographical distribution of LCT assemblages across southern Eurasia during the EMPT (Early-Middle Pleistocene Transition, circa 942 to 641 kyr). Up to now, chronology of the earliest European LCT assemblages is based on the abundant Palaeolithic record found in terrace river sequences which have been dated to the end of the EMPT and later. However, the findings at Barranc de la Boella suggest that early LCT lithic assemblages appeared in the SW of Europe during earlier hominin dispersal episodes before the definitive colonization of temperate Eurasia took place.

  19. Evaluating an unconfined aquifer by analysis of age-dating tracers in stream water

    NASA Astrophysics Data System (ADS)

    Solomon, D. K.; Gilmore, T. E.; Solder, J. E.; Kimball, B.; Genereux, D. P.

    2015-11-01

    The mean transit time (MTT) is a fundamental property of a groundwater flow system that is strongly related to the ratio of recharge rate to storage volume. However, obtaining samples for estimating the MTT using environmental tracers is problematic as flow-weighted samples over the full spectrum of transit times are needed. Samples collected from the base flow of a gaining stream in the North Carolina Coastal Plain (West Bear Creek) that were corrected for exchange with the atmosphere yielded environmental tracer concentrations (SF6 and CFC-11) very similar to flow-weighted values from nine or ten streambed piezometers that directly sampled groundwater during low streamflow. At higher streamflow on the falling limb of the hydrograph, stream tracer concentrations (after correction for gas exchange) were significantly higher than the flow-weighted mean from piezometers, consistent with dominance of the stream tracer signal by transient influx of surface water and/or younger subsurface water. The apparent MTT derived from SF6 in low flow stream water samples was 26 years, suggesting a groundwater recharge rate of about 210 mm/yr, that is consistent with vertical profiles obtained by sampling nested piezometers in the aquifer. When sampled under low flow conditions when streamflow consists of a high component of groundwater discharge, West Bear Creek appears to act as a flow-weighted integrator of transit times and, streamflow samples can provide fundamental information regarding groundwater recharge rate and MTT. Our study suggests that watershed-scale evaluation of some groundwater flow systems is possible without utilizing monitoring wells.

  20. Dating a small impact crater: An age of Kaali crater (Estonia) based on charcoal emplaced within proximal ejecta

    NASA Astrophysics Data System (ADS)

    Losiak, A.; Wild, E. M.; Geppert, W. D.; Huber, M. S.; Jõeleht, A.; Kriiska, A.; Kulkov, A.; Paavel, K.; Pirkovic, I.; Plado, J.; Steier, P.; VäLja, R.; Wilk, J.; Wisniowski, T.; Zanetti, M.

    2016-04-01

    The estimates of the age of the Kaali impact structure (Saaremaa Island, Estonia) provided by different authors vary by as much as 6000 years, ranging from ~6400 to ~400 before current era (BCE). In this study, a new age is obtained based on 14C dating charred plant material within the proximal ejecta blanket, which makes it directly related to the impact structure, and not susceptible to potential reservoir effects. Our results show that the Kaali crater was most probably formed shortly after 1530-1450 BCE (3237 ± 10 14C yr BP). Saaremaa was already inhabited when the bolide hit the Earth, thus, the crater-forming event was probably witnessed by humans. There is, however, no evidence that this event caused significant change in the material culture (e.g., known archeological artifacts) or patterns of human habitation on Saaremaa.

  1. Age-dating the Tully-Fisher relation at moderate redshift

    NASA Astrophysics Data System (ADS)

    Ferreras, Ignacio; Böhm, Asmus; Ziegler, Bodo; Silk, Joseph

    2014-01-01

    We analyse the Tully-Fisher relation at moderate redshift from the point of view of the underlying stellar populations, by comparing optical and NIR photometry with a phenomenological model that combines population synthesis with a simple prescription for chemical enrichment. The sample comprises 108 late-type galaxies extracted from the FORS Deep Field and William Herschel Deep Field surveys at z ≲ 1 (median redshift z = 0.45). A correlation is found between stellar mass and the parameters that describe the star formation history, with massive galaxies forming their populations early (zFOR ˜ 3), with star formation time-scales, τ1 ˜ 4 Gyr, although with very efficient chemical enrichment time-scales (τ2 ˜ 1 Gyr). In contrast, the stellar-to-dynamical mass ratio - which, in principle, would track the efficiency of feedback in the baryonic processes driving galaxy formation - does not appear to correlate with the model parameters. On the Tully-Fisher plane, no significant age segregation is found at fixed circular speed, whereas at fixed stellar-to-dynamical mass fraction, age splits the sample, with older galaxies having faster circular speeds at fixed Ms/Mdyn. Although our model does not introduce any prior constraint on dust reddening, we obtain a strong correlation between colour excess and stellar mass.

  2. Conception rates in farm mink (Neovison vison) in relation to first mating date, age and color variety.

    PubMed

    Felska-Błaszczyk, Lidia; Lasota, Bogdan; Seremak, Beata

    2016-07-01

    The aim of the study was to analyze the effects of the first mating date, age and color variety on the conception rates in farm mink. We analyzed female mink reproductive performance in 492 Sapphire and 463 Standard Black females over 3 or 4 years. The analysis included the number of inefficient matings, the interval between the first inefficient mating and the efficient mating (copulation) and the conception rates. The results show a significant effect of female's age and color variety on the conception rates. The youngest, yearling females of either color needed a higher number of matings per conception, as compared to older, 2- and 3-year-old females. Black females demonstrated a higher number of inefficient matings (1.066), as compared with Sapphires (0.730). Yearling females were most often mated from 1 to 10 March, and older females from 11 to 20 March. Older females achieved better conception rates than the yearlings. Dates between 11 and 25 March proved to be the optimum for the first mating, since the highest conception rates were observed if the females had mated during this period.

  3. Absence of age-related prefrontal NAA change in adults with autism spectrum disorders

    PubMed Central

    Aoki, Y; Abe, O; Yahata, N; Kuwabara, H; Natsubori, T; Iwashiro, N; Takano, Y; Inoue, H; Kawakubo, Y; Gonoi, W; Sasaki, H; Murakami, M; Katsura, M; Nippashi, Y; Takao, H; Kunimatsu, A; Matsuzaki, H; Tsuchiya, K J; Kato, N; Kasai, K; Yamasue, H

    2012-01-01

    Atypical trajectory of brain growth in autism spectrum disorders (ASDs) has been recognized as a potential etiology of an atypical course of behavioral development. Numerous neuroimaging studies have focused on childhood to investigate atypical age-related change of brain structure and function, because it is a period of neuron and synapse maturation. Recent studies, however, have shown that the atypical age-related structural change of autistic brain expands beyond childhood and constitutes neural underpinnings for lifelong difficulty to behavioral adaptation. Thus, we examined effects of aging on neurochemical aspects of brain maturation using 3-T proton magnetic resonance spectroscopy (1H-MRS) with single voxel in the medial prefrontal cortex (PFC) in 24 adult men with non-medicated high-functioning ASDs and 25 age-, IQ- and parental-socioeconomic-background-matched men with typical development (TD). Multivariate analyses of covariance demonstrated significantly high N-acetylaspartate (NAA) level in the ASD subjects compared with the TD subjects (F=4.83, P=0.033). The low NAA level showed a significant positive correlation with advanced age in the TD group (r=−0.618, P=0.001), but was not evident among the ASD individuals (r=0.258, P=0.223). Fisher's r-to-z transformation showed a significant difference in the correlations between the ASD and TD groups (Z=−3.23, P=0.001), which indicated that the age–NAA relationship was significantly specific to people with TD. The current 1H-MRS study provided new evidence that atypical age-related change of neurochemical aspects of brain maturation in ASD individuals expands beyond childhood and persists during adulthood. PMID:23092982

  4. Using 40Ar/39Ar ages of intercalated silicic tuffs to date flood basalts: Precise ages for Steens Basalt Member of the Columbia River Basalt Group

    NASA Astrophysics Data System (ADS)

    Mahood, Gail A.; Benson, Thomas R.

    2017-02-01

    To establish causality between flood basalt eruptions and extinction events and global environmental effects recorded by isotopic excursions in marine sediments, highly accurate and precise ages for the flood basalts are required. But flood basalts are intrinsically difficult to date. We illustrate how 40Ar/39Ar feldspar ages for silicic tuffs intercalated with and overlying sections of Steens Basalt, the earliest lavas of the Middle Miocene Columbia River Basalt Group in the northwestern United States, provide high-precision ages that, for the first time, make it possible to resolve age differences with stratigraphic position within a section of these flood lavas. The stratigraphically lowest rhyolitic tuff, a fall deposit, yielded an age of 16.592 ± ± 0.028 Ma (FCs = 28.02 Ma), and the uppermost, the alkali rhyolite ignimbrite Tuff of Oregon Canyon, is 16.468 ± ± 0.014 Ma. The argon and stratigraphic data indicate that Steens Basalt eruptions occurred from ∼16.64 to 16.43 Ma in the southern end of its distribution. We estimate that the Steens Mountain geomagnetic reversal occurred at 16.496 ± ± 0.028 Ma (±0.18 Ma total error). Our estimates of the timing for initiation of volcanism and volumetric eruptive rates do not seem to support volcanic forcing by the initial stages of Columbia River Basalt Group eruptions as an explanation for the abrupt warming and carbonate dissolution at the beginning of the Miocene Climatic Optimum.

  5. Fine-tuning of age integrating magnetostratigraphy, radiocarbon dating, and carbonate cyclicity: Example of lacustrine sediments from Heqing basin (Yunnan, China) covering the past 1 Myr

    NASA Astrophysics Data System (ADS)

    Hu, Shouyun; Goddu, Srinivasa Rao; Appel, Erwin; Verosub, Ken

    2007-05-01

    High-resolution magnetostratigraphy, wavelength spectra of carbonate cyclicities, and AMS radiocarbon dating are integrated to establish an optimum age model for a 168 m long drill core of lacustrine sediments from Heqing basin, Yunnan Province, southwestern China. A 14C age of 51.62 +2.42/-1.85 kyr BP is obtained at a depth of 7.3 m. Remanent magnetization is carried by maghemite and partly in addition by magnetite, both showing the same direction. The polarity sequence clearly reveals the Brunhes/Matuyama (B/M) boundary at 141.5 m. Blake Event is found between 16.3 and 17.5 m, and the upper boundary of Jaramillo is indicated at 167.0 m. Carbonate content and magnetic susceptibility were used for spectral analysis. Fourier analysis was done on the depth section for sliding windows with different window lengths. The spectra within the range of window centers (30-140 m) show a dominant long wavelength, which changes from about 18.5 m in the lower part (>65 m depth) to about 14.5 m in the upper part (<65 m depth) of the core. It is assumed that the long wavelength peak represents the 95-kyr Milankovitch eccentricity cycle. The B/M boundary and Blake Event match very well with this model, but the age of Jaramillo is strongly underestimated. Fourier spectra of sliding windows slightly indicate a drop of the sedimentation rate at the lowermost part of the core. An optimum age model is calculated by cubic spline interpolation using tie points from 14C dating, magnetostratigraphy ('true' ages of Blake Event, B/M boundary, and Jaramillo), and wavelengths of carbonate (change in sedimentation rate at 65 m). Alternative depth-to-age transfer functions were tested, i.e. a wavelength age model (using sedimentation rates with 14C as a tie point), a cyclostratigraphic model (using bandpass-filtered carbonate data corresponding to 95 kyr eccentricity cycles) and correlation of carbonate variations to the marine oxygen isotope curve. However, none of the approaches lead to a

  6. Summary of Age-Dating Analysis in the Fenner Basin, Eastern Mojave Desert, California

    SciTech Connect

    Davisson, M.L.

    2000-06-01

    Stable isotopes of oxygen (oxygen-18) and hydrogen (deuterium) in water were measured to determine recharge sources for Fenner Basin groundwater. The deuterium and oxygen-18 signatures (reported as {delta}D and {delta}{sup 18}O values) ranged from -11.9 to -9.3 per mil. The more negative values originate from high elevation recharge in the New York Mountains and were also observed in the northern and eastern parts of the groundwater basin. less negative values were observed in the Providence Mountains along the western part of the basin. Groundwater collected in the Fenner Gap (i.e. Project Area) had signatures between -10.6 and -10.9 per mil, suggesting a mixture of recharge from both northern, western, and probably local recharge areas in the basin. The annual contribution of groundwater recharge to Fenner Gap from the Clipper, Marble, and Old Woman mountains is still inconclusive due to lack of isotopic data. Isotopic signatures of mean annual precipitation collected by Friendman and others (1992) at Mitchell Caverns, as well as recently recharged groundwater in the Providence and New York mountains, are similar to the isotopic values in Fenner Gap groundwater. This indicates that this groundwater has a Holocene age (less than 10,000 years old), since groundwater recharged during the Pleistocene had isotopic signatures significantly more negative than today due to past global cooling.

  7. Age Dating Merger Events in Early Type Galaxies via the Detection of AGB Light

    NASA Technical Reports Server (NTRS)

    Bothun, G.

    2005-01-01

    A thorough statistical analysis of the J-H vs. H-K color plane of all detected early type galaxies in the 2MASS catalog with velocities less than 5000 km/s has been performed. This all sky survey is not sensitive to one particular galactic environment and therefore a representative range of early type galaxy environments have been sampled. Virtually all N-body simulation so major mergers produces a central starburst due to rapid collection of gas. This central starburst is of sufficient amplitude to change the stellar population in the central regions of the galaxy. Intermediate age populations are given away by the presence of AGB stars which will drive the central colors redder in H-K relative to the J- H baseline. This color anomaly has a lifetime of 2-5 billion years depending on the amplitude of the initial starburst Employing this technique on the entire 2MASS sample (several hundred galaxies) reveals that the AGB signature occurs less than 1% of the time. This is a straightforward indication that virtually all nearby early type galaxies have not had a major merger occur within the last few billion years.

  8. Inter-comparison exercises on dissolved gases for groundwater dating (GDAT 2012) : analytical uncertainties, apparent ages and other derived parameters.

    NASA Astrophysics Data System (ADS)

    Labasque, Thierry; Aquilina, Luc; Visser, Ate; Vergnaud, Virginie

    2014-05-01

    An inter-laboratory comparison exercise dedicated to environmental tracers used for groundwater dating was organized in 2012 in France. The goal was to compare sampling and analytical protocols through results obtained by the community of groundwater dating laboratories. Sampling and analytical protocols were compared through three different exercises on various supports : (1) on groundwater from a homogeneous aquifer, (2) on groundwater from a fractured heterogeneous aquifer and (3) on an air standard. The two tests allowed 31 Laboratories from 14 countries to compare their protocols for both sampling and analyses. It allows discussing the uncertainties related to sampling protocols issuing from each laboratory methods. The results show a good agreement between laboratories on the aquifers and the air standard. The dispersion of SF6 results in air standard is low (rsd 2%) compared to CFCs (rsd 3 to 7%), even if its concentration is two orders of magnitude lower. Results obtained in recent groundwater (recharge after 1980) show that the uncertainty on groundwater dating with SF6 is between 3 and 4 years. This large uncertainty is mainly due to sampling and/or analytical problems. For CFCs, uncertainties obtained over all the laboratories are less than 2 years for groundwater with recharge between 1965 and 1996. The goal of the inter-laboratory comparison exercise was also to quantify the analytical uncertainty of the 3H and noble gas measurements and to assess whether they meet the requirements for 3H/3He dating and noble gas paleotemperature reconstruction. The reproducibility of the tritium measurements was 13.5%. The reproducibility of the 3He/4He ratio and 4He, Ne, Ar, Kr and Xe concentrations was 1.4%, 1.8%, 1.5%, 2.2%, 2.9%, and 2.4%. The propagated uncertainty of the tritium and noble gas measurements meets the desired precision for typical 3H/3He dating applications. However, the measurement uncertainties for the noble gas concentrations are insufficient to

  9. Comparison of chlorofluorocarbon-age dating with particle-tracking results of a regional ground-water flow model of the Portland Basin, Oregon and Washington

    USGS Publications Warehouse

    Hinkle, Stephen R.; Snyder, Daniel T.

    1997-01-01

    This report describes the results of a study in which chlorofluorocarbon-age dating was used to evaluate the results of a ground-water particle tracker for the Portland Basin in Oregon and Washington.

  10. Employment Outcomes of Transition-Aged Adults with Autism Spectrum Disorders: A State of the States Report

    ERIC Educational Resources Information Center

    Burgess, Sloane; Cimera, Robert E.

    2014-01-01

    The primary purpose of this study was to evaluate the employment outcomes of transition-aged adults with autism spectrum disorders (ASD) served by vocational rehabilitation services (VR) over the last 10 years by state. A secondary purpose was to compare employment outcomes of individuals with ASD to those of the overall transition-aged population…

  11. Age Differences in Emergency Department Visits and Inpatient Hospitalizations in Preadolescent and Adolescent Youth with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Schlenz, Alyssa M.; Carpenter, Laura A.; Bradley, Catherine; Charles, Jane; Boan, Andrea

    2015-01-01

    This paper evaluated age differences in emergency department care and inpatient hospitalizations in 252 preadolescent and adolescent youth with autism spectrum disorders (ASDs; ages 9-18). Records from youth with ASDs were linked to acute care utilization records and were compared to a demographically similar comparison group of youth without ASDs…

  12. Changes in Restricted Repetitive Behaviors with Age: A Study of High-Functioning Adults with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Chowdhury, Monali; Benson, Betsey A.; Hillier, Ashleigh

    2010-01-01

    The existing literature suggests that while impairments in Autism Spectrum Disorders (ASDs) continue into adulthood, some behavioral symptoms tend to abate with age. However, there is a dearth of research examining changes in ASD symptoms from childhood to adulthood, especially for Restricted Repetitive Behaviors (RRBs). We examined age-related…

  13. Development of the Conversation Participation Rating Scale: Intervention Planning Implications for Two School-Age Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Timler, Geralyn R.; Boone, William J.; Bergmann, Amelia A.

    2014-01-01

    Purpose: School-age children with autism spectrum disorders (ASDs) have pervasive challenges in social interactions with peers. This study examined the feasibility of eliciting children's perceptions of their conversation participation with peers for the purposes of assessment and intervention planning. Methods: Two school-age children with ASD…

  14. Associations between Verbal Learning Slope and Neuroimaging Markers across the Cognitive Aging Spectrum.

    PubMed

    Gifford, Katherine A; Phillips, Jeffrey S; Samuels, Lauren R; Lane, Elizabeth M; Bell, Susan P; Liu, Dandan; Hohman, Timothy J; Romano, Raymond R; Fritzsche, Laura R; Lu, Zengqi; Jefferson, Angela L

    2015-07-01

    A symptom of mild cognitive impairment (MCI) and Alzheimer's disease (AD) is a flat learning profile. Learning slope calculation methods vary, and the optimal method for capturing neuroanatomical changes associated with MCI and early AD pathology is unclear. This study cross-sectionally compared four different learning slope measures from the Rey Auditory Verbal Learning Test (simple slope, regression-based slope, two-slope method, peak slope) to structural neuroimaging markers of early AD neurodegeneration (hippocampal volume, cortical thickness in parahippocampal gyrus, precuneus, and lateral prefrontal cortex) across the cognitive aging spectrum [normal control (NC); (n=198; age=76±5), MCI (n=370; age=75±7), and AD (n=171; age=76±7)] in ADNI. Within diagnostic group, general linear models related slope methods individually to neuroimaging variables, adjusting for age, sex, education, and APOE4 status. Among MCI, better learning performance on simple slope, regression-based slope, and late slope (Trial 2-5) from the two-slope method related to larger parahippocampal thickness (all p-values<.01) and hippocampal volume (p<.01). Better regression-based slope (p<.01) and late slope (p<.01) were related to larger ventrolateral prefrontal cortex in MCI. No significant associations emerged between any slope and neuroimaging variables for NC (p-values ≥.05) or AD (p-values ≥.02). Better learning performances related to larger medial temporal lobe (i.e., hippocampal volume, parahippocampal gyrus thickness) and ventrolateral prefrontal cortex in MCI only. Regression-based and late slope were most highly correlated with neuroimaging markers and explained more variance above and beyond other common memory indices, such as total learning. Simple slope may offer an acceptable alternative given its ease of calculation.

  15. Gestational Age and Autism Spectrum Disorder: Trends in Risk Over Time.

    PubMed

    Atladóttir, H Ó; Schendel, D E; Henriksen, T B; Hjort, L; Parner, E T

    2016-02-01

    Autism Spectrum Disorder (ASD) is a serious neurodevelopmental disorder. Several previous studies have identified preterm birth as a risk factor for ASD but none has studied whether the association between gestational age and ASD has changed over time. This is a Danish population-based follow-up study including live-born singletons born in Denmark between 1980 and 2009, identified in the Danish Medical Birth Registry, a study population of 1,775,397 children. We used a Cox regression model combined with spline to study the risk for ASD by gestational age across three decades of birth cohorts. We included 19,020 children diagnosed with ASD. Across all birth year cohorts, we found that the risk of being diagnosed with ASD increased with lower gestational age (P-value: <0.01). Across all gestational weeks, we found a statistically significant higher risk estimates in birth cohort 1980 to 1989, compared to birth cohorts 1990 to 1999 and 2000 to 2009, respectively. No statistically significant difference in risk estimates was observed between birth cohort 1990 to 1999 and 2000 to 2009. The observed time trend in risk of ASD after preterm birth may reflect: (1) a change in the risk profile of persons with ASD due to the broadening of ASD diagnostic criteria over time; or (2) improved neonatal care for low GA infants, which has reduced risk of adverse outcomes like ASD in preterm children.

  16. What distinguishes autism spectrum disorders from other developmental disorders before the age of four years?

    PubMed

    Trillingsgaard, Anegen; Ulsted Sørensen, Ester; Nemec, Gerda; Jørgensen, Meta

    2005-03-01

    The increasing recognition of the benefits of early intervention for children with autism spectrum disorder (ASD) stresses the importance of early identification of children who might benefit from those programs. However, in the early years of life it may be difficult to distinguish children with ASD from children with other developmental disorders. The aim of the present study was to identify behavioural patterns that could facilitate this differentiation. Prior to diagnostic assessment, 2- and 3-year-old children (n=30), all referred to a clinic for "possible autism", were observed in a semi-structured play interaction, and their parents were interviewed about the children's early development from 0 to 24 months. Following diagnostic assessment, the 17 children fulfilling the ICD-10 criteria for ASD were compared to the 13 children diagnosed with other developmental disorders (outside the autism spectrum). On the basis of parent reports only a few distinguishing signs of ASD were found before 24 months of age. On the basis of professional observations in a semi-structured play interaction several distinguishing signs were found for the 2- and 3-year-olds; smiles in response, responds to name, follows pointing, looks to "read" faces, initiates requesting verbal and nonverbal behaviours, and functional play.

  17. A simple-rapid method to separate uranium, thorium, and protactinium for U-series age-dating of materials.

    PubMed

    Knight, Andrew W; Eitrheim, Eric S; Nelson, Andrew W; Nelson, Steven; Schultz, Michael K

    2014-08-01

    Uranium-series dating techniques require the isolation of radionuclides in high yields and in fractions free of impurities. Within this context, we describe a novel-rapid method for the separation and purification of U, Th, and Pa. The method takes advantage of differences in the chemistry of U, Th, and Pa, utilizing a commercially-available extraction chromatographic resin (TEVA) and standard reagents. The elution behavior of U, Th, and Pa were optimized using liquid scintillation counting techniques and fractional purity was evaluated by alpha-spectrometry. The overall method was further assessed by isotope dilution alpha-spectrometry for the preliminary age determination of an ancient carbonate sample obtained from the Lake Bonneville site in western Utah (United States). Preliminary evaluations of the method produced elemental purity of greater than 99.99% and radiochemical recoveries exceeding 90% for U and Th and 85% for Pa. Excellent purity and yields (76% for U, 96% for Th and 55% for Pa) were also obtained for the analysis of the carbonate samples and the preliminary Pa and Th ages of about 39,000 years before present are consistent with (14)C-derived age of the material.

  18. Mechanism of inflammation in age-related macular degeneration: an up-to-date on genetic landmarks.

    PubMed

    Parmeggiani, Francesco; Sorrentino, Francesco S; Romano, Mario R; Costagliola, Ciro; Semeraro, Francesco; Incorvaia, Carlo; D'Angelo, Sergio; Perri, Paolo; De Nadai, Katia; Bonomo Roversi, Elia; Franceschelli, Paola; Sebastiani, Adolfo; Rubini, Michele

    2013-01-01

    Age-related macular degeneration (AMD) is the most common cause of irreversible visual impairment among people over 50 years of age, accounting for up to 50% of all cases of legal blindness in Western countries. Although the aging represents the main determinant of AMD, it must be considered a multifaceted disease caused by interactions among environmental risk factors and genetic backgrounds. Mounting evidence and/or arguments document the crucial role of inflammation and immune-mediated processes in the pathogenesis of AMD. Proinflammatory effects secondary to chronic inflammation (e.g., alternative complement activation) and heterogeneous types of oxidative stress (e.g., impaired cholesterol homeostasis) can result in degenerative damages at the level of crucial macular structures, that is photoreceptors, retinal pigment epithelium, and Bruch's membrane. In the most recent years, the association of AMD with genes, directly or indirectly, involved in immunoinflammatory pathways is increasingly becoming an essential core for AMD knowledge. Starting from the key basic-research notions detectable at the root of AMD pathogenesis, the present up-to-date paper reviews the best-known and/or the most attractive genetic findings linked to the mechanisms of inflammation of this complex disease.

  19. Paleointensity record in zero-age submarine basalt glasses: testing a new dating technique for recent MORBs

    NASA Astrophysics Data System (ADS)

    Carlut, J.; Kent, D. V.

    2000-12-01

    Thellier-Thellier paleointensity experiments were conducted on a collection of glasses from three very recent submarine axial flows. Two were erupted along the Juan de Fuca ridge at around 46°N and one along the East Pacific Rise South at around 18°S. The within-sample dispersion of paleointensity results from the 'Animal Farm' flow (EPR south) is very low and leads to a well-defined mean value of 35.6±1 μT (95% error on the mean) based on 11 glass chips from four independent samples. Today's geomagnetic field intensity in the area is 31.2 μT. Comparing Animal Farm results with published field model reference curves developed for the past 400 yr suggests an eruptive date estimated between 1880 A.D. and 1950 A.D. (taking into account different sources of errors). This is consistent with qualitative evidence for the age of this flow and constitutes the first precise demonstration of using paleointensity as a dating tool for very recent mid-ocean ridge basalts (MORBs). However in the Juan de Fuca area results show a more erratic pattern with samples varying by up to 30% higher and lower from the expected value of about 55 μT. The dispersion is attributed to the large local crustal magnetic anomalies in this area that can lead to inconsistent intensity values over the same unit. Local magnetic anomalies should thus always be checked when doing paleointensity on MORB samples which should also be distributed as widely as possible in a flow unit. When no significant magnetic anomalies are detected the paleointensity dating tool is anticipated to be especially efficient to investigate the volcanic cyclicity along the EPR axis during the last several hundred years.

  20. Nonverbal and verbal cognitive discrepancy profiles in autism spectrum disorders: influence of age and gender.

    PubMed

    Ankenman, Katy; Elgin, Jenna; Sullivan, Katherine; Vincent, Logan; Bernier, Raphael

    2014-01-01

    Research suggests that discrepant cognitive abilities are more common in children with autism spectrum disorder (ASD) and may indicate an important ASD endophenotype. The current study examined the frequency of IQ discrepancy profiles (nonverbal IQ > verbal IQ [NVIQ > VIQ], verbal IQ > nonverbal IQ [VIQ > NVIQ], and no split) and the relationship of gender, age, and ASD symptomatology to IQ discrepancy profile in a large sample of children with ASD. The NVIQ > VIQ profile occurred at a higher frequency than expected, had more young males, and showed more autism symptoms than the other groups. Results suggest that the NVIQ > VIQ profile may be less likely to represent a subtype of ASD, but rather a common developmental pathway for children with ASD and other disorders.

  1. Fungal Root Microbiome from Healthy and Brittle Leaf Diseased Date Palm Trees (Phoenix dactylifera L.) Reveals a Hidden Untapped Arsenal of Antibacterial and Broad Spectrum Antifungal Secondary Metabolites.

    PubMed

    Mefteh, Fedia B; Daoud, Amal; Chenari Bouket, Ali; Alenezi, Faizah N; Luptakova, Lenka; Rateb, Mostafa E; Kadri, Adel; Gharsallah, Neji; Belbahri, Lassaad

    2017-01-01

    In this study, we aimed to explore and compare the composition, metabolic diversity and antimicrobial potential of endophytic fungi colonizing internal tissues of healthy and brittle leaf diseased (BLD) date palm trees (Phoenix dactylifera L.) widely cultivated in arid zones of Tunisia. A total of 52 endophytic fungi were isolated from healthy and BLD roots of date palm trees, identified based on internal transcribed spacer-rDNA sequence analysis and shown to represent 13 species belonging to five genera. About 36.8% of isolates were shared between healthy and diseased root fungal microbiomes, whereas 18.4 and 44.7% of isolates were specific to healthy and BLD root fungal microbiomes, respectively. All isolates were able to produce at least two of the screened enzymes including amylase, cellulase, chitinase, pectinase, protease, laccase and lipase. A preliminary screening of the isolates using disk diffusion method for antibacterial activity against four Gram-positive and three Gram-negative bacteria and antifungal activities against three phytopathogenic fungi indicated that healthy and BLD root fungal microbiomes displayed interesting bioactivities against examined bacteria and broad spectrum bioactivity against fungal pathogens. Some of these endophytic fungi (17 isolates) were fermented and their extracts were evaluated for antimicrobial potential against bacterial and fungal isolates. Results revealed that fungal extracts exhibited antibacterial activities and were responsible for approximately half of antifungal activities against living fungi. These results suggest a strong link between fungal bioactivities and their secondary metabolite arsenal. EtOAc extracts of Geotrichum candidum and Thielaviopsis punctulata originating from BLD microbiome gave best results against Micrococcus luteus and Bacillus subtilis with minimum inhibitory concentration (MIC, 0.78 mg/mL) and minimum bactericidal concentration (6.25 mg/mL). G. candidum gave the best result against

  2. Fungal Root Microbiome from Healthy and Brittle Leaf Diseased Date Palm Trees (Phoenix dactylifera L.) Reveals a Hidden Untapped Arsenal of Antibacterial and Broad Spectrum Antifungal Secondary Metabolites

    PubMed Central

    Mefteh, Fedia B.; Daoud, Amal; Chenari Bouket, Ali; Alenezi, Faizah N.; Luptakova, Lenka; Rateb, Mostafa E.; Kadri, Adel; Gharsallah, Neji; Belbahri, Lassaad

    2017-01-01

    In this study, we aimed to explore and compare the composition, metabolic diversity and antimicrobial potential of endophytic fungi colonizing internal tissues of healthy and brittle leaf diseased (BLD) date palm trees (Phoenix dactylifera L.) widely cultivated in arid zones of Tunisia. A total of 52 endophytic fungi were isolated from healthy and BLD roots of date palm trees, identified based on internal transcribed spacer-rDNA sequence analysis and shown to represent 13 species belonging to five genera. About 36.8% of isolates were shared between healthy and diseased root fungal microbiomes, whereas 18.4 and 44.7% of isolates were specific to healthy and BLD root fungal microbiomes, respectively. All isolates were able to produce at least two of the screened enzymes including amylase, cellulase, chitinase, pectinase, protease, laccase and lipase. A preliminary screening of the isolates using disk diffusion method for antibacterial activity against four Gram-positive and three Gram-negative bacteria and antifungal activities against three phytopathogenic fungi indicated that healthy and BLD root fungal microbiomes displayed interesting bioactivities against examined bacteria and broad spectrum bioactivity against fungal pathogens. Some of these endophytic fungi (17 isolates) were fermented and their extracts were evaluated for antimicrobial potential against bacterial and fungal isolates. Results revealed that fungal extracts exhibited antibacterial activities and were responsible for approximately half of antifungal activities against living fungi. These results suggest a strong link between fungal bioactivities and their secondary metabolite arsenal. EtOAc extracts of Geotrichum candidum and Thielaviopsis punctulata originating from BLD microbiome gave best results against Micrococcus luteus and Bacillus subtilis with minimum inhibitory concentration (MIC, 0.78 mg/mL) and minimum bactericidal concentration (6.25 mg/mL). G. candidum gave the best result against

  3. Age and evolution of the Grand Canyon revealed by U-Pb dating of water table-type speleothems.

    PubMed

    Polyak, Victor; Hill, Carol; Asmerom, Yemane

    2008-03-07

    The age and evolution of the Grand Canyon have been subjects of great interest and debate since its discovery. We found that cave mammillaries (water table indicator speleothems) from nine sites in the Grand Canyon showed uranium-lead dating evidence for an old western Grand Canyon on the assumption that groundwater table decline rates are equivalent to incision rates. Samples in the western Grand Canyon yielded apparent water table decline rates of 55 to 123 meters per million years over the past 17 million years, in contrast to eastern Grand Canyon samples that yielded much faster rates (166 to 411 meters per million years). Chronology and inferred incision data indicate that the Grand Canyon evolved via headward erosion from west to east, together with late-stage ( approximately 3.7 million years ago) accelerated incision in the eastern block.

  4. Detecting, sourcing, and age-dating dredged sediments on the open shelf, southern California, using dead mollusk shells.

    PubMed

    Bizjack, Matthew T; Kidwell, Susan M; Velarde, Ronald G; Leonard-Pingel, Jill; Tomašových, Adam

    2017-01-15

    Molluscan shell debris is an under-exploited means of detecting, sourcing, and age-dating dredged sediments in open-shelf settings. Backscatter features on the Southern California shelf are suggestive of dredged sediment hauled from San Diego Bay but deposited significantly inshore of the EPA-designated ocean disposal site. We find that 36% of all identifiable bivalve shells >2mm (44% of shells >4mm) in sediment samples from this 'short dump' area are from species known to live exclusively in the Bay; such shells are absent at reference sites of comparable water depth, indicating that their presence in the short-dump area signals non-compliant disposal rather than natural offshore transport or sea level rise. These sediments lack the shells of species that invaded California bays in the 1970s, suggesting that disposal preceded federal regulations. This inexpensive, low-tech method, with its protocol for rejecting alternative hypotheses, will be easy to adapt in other settings.

  5. Psychiatric Co-Occurring Symptoms and Disorders in Young, Middle-Aged, and Older Adults with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Lever, Anne G.; Geurts, Hilde M.

    2016-01-01

    Although psychiatric problems are less prevalent in old age within the general population, it is largely unknown whether this extends to individuals with autism spectrum disorders (ASD). We examined psychiatric symptoms and disorders in young, middle-aged, and older adults with and without ASD (N[subscript max] = 344, age 19-79 years, IQ > 80).…

  6. Meteoric diagenesis of catastrophic rockslide deposits of the Alps: diagenetic systems and implications for radiometric age-dating.

    NASA Astrophysics Data System (ADS)

    Sanders, D.; Ostermann, M.; Kramers, J.; Brandner, R.

    2009-04-01

    Deposits of catastrophic subaerial rockslides (=rapid mass-wasting events involving more than a million cubic meters of rock) composed of lithologies rich in carbonate minerals may undergo precipitation of cements that, in many cases, can be used to U/Th proxy-date the rockslide event and/or subsequent changes of the rockslide mass. In the Alps, lithification of rockslide masses into breccias is observed in rockslides composed of limestones, dolostones, calcitic-dolomitic marbles, and calcphyllites. Cementation may be localized to meteoric 'runoff-shadows' below larger boulders, or may comprise a continous surface veneer of breccia or, more rarely, may affect the entire rockslide mass. In addition, precipitation of flowstone cements and stalactites may take place in megapores along the underside of boulders. Cements comprise skalenohedral calcite, prismatic calcite, blocky calcite, calcimicrite, micropeloidal calcitic cement and, rarely, isopachous to botryoidal aragonite. Cement formation probably is driven by meteoric dissolution-reprecipitation of fine-grained, abrasive rock powder generated during the rockslide event. U/Th ages of cements indicate that most, but not all, precipitation starts closely after a rockslide event. In rockslides composed of calcphyllites with an accessory content of pyrite, aside of 'normal' meteoric dissolution-reprecipitation of abrasive carbonate gauge, oxidation of pyrite drives widespread carbonate dissolution followed by reprecipitation, as a cement, of part of the dissolved calcium carbonate. Drill coring indicates that rockslide deposits composed of pyritiferous calcphyllites can be lithified from top to bottom. Limestone-precipitating springs emerging from rockslide deposits, and well-cemented 'secondary' deposits (e. g. talus slopes or fluvial conglomerates onlapping rockslide deposits) percolated by groundwaters emerging from rockslide masses, indicate that rockslide deposits remain diagenetically active for thousands of

  7. Use of chlorofluorocarbons (CCl3F and CCl2F2) as hydrologic tracers and age-dating tools: The alluvium and terrace system of central Oklahoma

    USGS Publications Warehouse

    Busenberg, Eurybiades; Plummer, L. Niel

    1992-01-01

    The use of Chlorofluorocarbons (CFCs) as an age-dating tool and tracer in shallow groundwaters has been investigated. New methodology for field sampling and preserving groundwaters containing parts per trillion concentrations of the CFCs, F-1l and F-12, is presented. Samples are analyzed by purge-and-trap gas chromatography with an electron capture detector. Physical and chemical processes that can alter natural concentrations (air-water equilibrium) of CFCs were investigated to assess dating uncertainties. CFC model recharge ages appear to be defined within 2 years under optimum conditions. The method was applied to central Oklahoma to demonstrate the usefulness of CFCs as (1) an age-dating tool of shallow groundwaters, (2) a tracer of sewage effluent in surface and shallow groundwaters, and (3) a tracer of shallow groundwater. Results of dating indicate two primary recharge periods in central Oklahoma over the past 45 years that correspond to the wet periods 1945–1960 and 1967–1975.

  8. Alteration of functional connectivity in autism spectrum disorder: effect of age and anatomical distance

    PubMed Central

    Long, Zhiliang; Duan, Xujun; Mantini, Dante; Chen, Huafu

    2016-01-01

    Autism spectrum disorder (ASD) is associated with disruption of local- and long-range functional connectivity (FC). The direction of those changes in FC (increase or decrease), however, is inconsistent across studies. Further, age-dependent changes of distance-specific FC in ASD remain unclear. In this study, we used resting-state functional magnetic resonance imaging data from sixty-four typical controls (TC) and sixty-four patients with ASD, whom we further classified into child (<11 years), adolescent (11–18 years) and adult cohorts (>18 years). Functional connectivity (FC) analysis was conducted at voxel level. We employed a three-way analysis of covariance on FC to conduct statistical analyses. Results revealed that patients with ASD had lower FC than TC in cerebellum, fusiform gyrus, inferior occipital gyrus and posterior inferior temporal gyrus. Significant diagnosis-by-distance interaction was observed in ASD patients with reduced short-range and long-range FC in posterior cingulate cortex and medial prefrontal cortex. Importantly, we found significant diagnosis-by-age-by-distance interaction in orbitofrontal cortex with short-range FC being lower in autistic children, but –to a less extent– higher in autistic adults. Our findings suggest a major role of connection length in development changes of FC in ASD. We hope our study will facilitate deeper understanding of the neural mechanisms underlying ASD. PMID:27194227

  9. Isotopic age of the Black Forest Bed, Petrified Forest Member, Chinle Formation, Arizona: An example of dating a continental sandstone

    USGS Publications Warehouse

    Riggs, N.R.; Ash, S.R.; Barth, A.P.; Gehrels, G.E.; Wooden, J.L.

    2003-01-01

    Zircons from the Black Forest Bed, Petrified Forest Member, Chinle Formation, in Petrified Forest National Park, yield ages that range from Late Triassic to Late Archean. Grains were analyzed by multigrain TIMS (thermal-ionization mass spectrometry), single-crystal TIMS, and SHRIMP (sensitive, high-resolution ion-microprobe). Multiple-grain analysis yielded a discordia trajectory with a lower intercept of 207 ?? 2 Ma, which because of the nature of multiple-grain sampling of a detrital bed, is not considered conclusive. Analysis of 29 detrital-zircon grains by TIMS yielded U-PB ages of 2706 ?? 6 Ma to 206 ?? 6 Ma. Eleven of these ages lie between 211 and 216 ?? 6.8 Ma. Our statistical analysis of these grains indicates that the mean of the ages, 213 ?? 1.7 Ma, reflects more analytical error than geologic variability in sources of the grains. Grains with ages of ca. 1400 Ma were derived from the widespread plutons of that age exposed throughout the southwestern Cordillera and central United States. Twelve grains analyzed by SHRIMP provide 206Pb*/238U ages from 214 ?? 2 Ma to 200 ?? 4 Ma. We use these data to infer that cores of inherited material were present in many zircons and that single-crystal analysis provides an accurate estimation of the age of the bed. We further propose that, even if some degree of reworking has occurred, the very strong concentration of ages at ca. 213 Ma provides a maximum age for the Black Forest Bed of 213 ?? 1.7 Ma. The actual age of the bed may be closer to 209 Ma. Dating continental successions is very difficult when distinct ash beds are not clearly identified, as is the case in the Chinle Formation. Detrital zircons in the Black Forest Bed, however, are dominated by an acicular morphology with preserved delicate terminations. The shape of these crystals and their inferred environment of deposition in slow-water settings suggest that the crystals were not far removed from their site of deposition in space and likely not far in time

  10. Age of the North Anatolian Fault Segments in the Yalova with U/Th Dating Method by Travertine Data

    NASA Astrophysics Data System (ADS)

    Selim, Haluk; Ömer Taş, K.

    2016-04-01

    Travertine occurrences developed along the segments of the North Anatolian Fault (NAF) in the south of Yalova. Travertines outcrop approximately 1 km2 area. These are middle-thick bedded approximately 20-40 m and back-tilted southward or horizontally. Lithology of travertines deposited such as physolite, stalactites-stalagmites, cave pearls, sharp pebble carbonate nodules, spherical-roller-intricate shapes or laminated banded travertine. Geochemical analyses were performed on the six samples of the travertines. X-ray analysis indicates that all samples are entirely composed of low-Mg calcite. Banded travertines with some tubular structures formed by precipitation from rising hot water are best developed near the toes of the large, hanging-wall-derived alluvial fans, whereas phreatic cement preferentially exists in footwall-derived, alluvial-fan conglomerates. The unit developed clarity which is controlled by normal fault as the structural and morphological, relationship with active tectonics. The travertines are a range-front type. U/Th series age dating results indicate that the travertine deposition extends back to 155 ka and yields ages of 60.000 (± 3, 091) to 153.149 (±13,466) from the range-front type travertines.

  11. Noble Gas Analysis for Mars Robotic Missions: Evaluating K-Ar Age Dating for Mars Rock Analogs and Martian Shergottites

    NASA Technical Reports Server (NTRS)

    Park, J.; Ming, D. W.; Garrison, D. H.; Jones, J. H.; Bogard, D. D.; Nagao, K.

    2009-01-01

    The purpose of this noble gas investigation was to evaluate the possibility of measuring noble gases in martian rocks and air by future robotic missions such as the Mars Science Laboratory (MSL). The MSL mission has, as part of its payload, the Sample Analysis at Mars (SAM) instrument, which consists of a pyrolysis oven integrated with a GCMS. The MSL SAM instrument has the capability to measure noble gas compositions of martian rocks and atmosphere. Here we suggest the possibility of K-Ar age dating based on noble gas release of martian rocks by conducting laboratory simulation experiments on terrestrial basalts and martian meteorites. We provide requirements for the SAM instrument to obtain adequate noble gas abundances and compositions within the current SAM instrumental operating conditions, especially, a power limit that prevents heating the furnace above approx.1100 C. In addition, Martian meteorite analyses from NASA-JSC will be used as ground truth to evaluate the feasibility of robotic experiments to constrain the ages of martian surface rocks.

  12. Practicability of In Situ K-Ar Age Dating by Martian Landers; A Study of Mars Analogs and Meteorites

    NASA Astrophysics Data System (ADS)

    Park, Jisun; Ming, D. W.; Garrison, D. H.; Jones, J. H.; Bogard, D. D.

    2009-12-01

    Purpose of this noble gas investigation was to evaluate the feasibility of in situ K-Ar radiometric age dating of Martian surface rocks by future robotic missions, such as the Mars Science Laboratory(MSL), under constraints inherent to the Martian surface and lander design. The MSL Sample Analysis at Mars(SAM) instrument has the capability to measure noble gas compositions of Martain rocks and atmosphere. We evaluate requirements for SAM to obtain adequate noble gas abundances and compositions within the current instrumental operating conditions. In particular, maximum furnace temperature is limited to 1100ºC or lower due to power supply constraints. As a simulation experiment, we analyzed three Martian shergottites and terrestrial MORB, under the same conditions afforded SAM on the Martian surface. Our results suggest that SAM noble gas recoveries might be sufficient for K-Ar age determinations. Comparing these results with previous experiments performed on Martian meteorites at NASA-JSC, we can asses the capability of Mars lander designs with a variety of Martian rock types. The noble gas composition of Martian meteorites can be difficult to interpret due to the combined signals of in situ 40K decay, shock implanted 40Ar from Martian atmosphere[2,3], and 40Ar inherited from parent magma[4,5]. These components should also be considered in interpreting lander data. A possible advantage for landers is that K concentrations reported from the Martian surface are variable and possibly quite high, a desirable trait for K-Ar age dating. Spirit APXS reports 3000-7000ppm K for most locations but in some areas, concentrations as high as 25000ppm have been observed[6,7]. [1] Bogard (2009) MaPS44, 3-14; [2] Bogard and Johnson (1983) Science221,651-654 [3] Marti et al. (1995) Science267, 1981-1984; [4] Bogard and Park (2008) MAPS43, 1113-1126. [5] Bogard et al. (2009) MAPS44, 905-923. [6] Ming et al. (2006) JGR111, E02S12. [7] Ming D.W. et al. (2008) JGR113, E12S39.

  13. Dating Wood-Benthic Foram-Planktic Foram Trios from the Panama Basin to Better Constrain Antarctic Intermediate Water Ventilation Age during the Last Deglaciation

    NASA Astrophysics Data System (ADS)

    Zhao, N.; Keigwin, L. D.

    2014-12-01

    Surface reservoir age complicates the age models of marine sediment records. Age model uncertainty may cause different interpretations of the same process. For example, in order to circumvent dealing with surface reservoir age, Marchitto et al. (2007) built their age model on a linkage to Greenland oxygen isotope record. But the proxy they used for the linkage was a minor factor of the sediment diffuse spectral reflectance, and they assumed the sedimentation rate was constant between the tie points which could be several thousand years apart. Based on that age model they showed the Antarctic Intermediate Water (AAIW) was significantly older during deglaciation than LGM and Holocene. However, de Pol-Holz et al. (2010) argued that the change of deglacial AAIW radiocarbon age was not clearly different from the atmospheric change. Their age model was based on planktic foram (PF) 14C dates and an assumption that the surface reservoir age was constantly 400 years for a site near an upwelling region. These records are only as good as their age models. Here, we present a new way to build the age model of marine records, which is to date wood in marine sediments. We found a core in Panama Basin with constantly-present twigs at the same water depth with the core used by Marchitto et al. (705m), and the radiocarbon dates of the wood samples give a very good age-depth relationship without any age reversal. With benthic foram (BF) dated in the same layer where the twigs appear, we will be able to compare the AAIW radiocarbon concentration directly with the atmosphere. In this way, we can get the AAIW ventilation age without worrying about the surface reservoir age and elucidate whether there indeed was old water transported northward by AAIW during the last deglaciation. This would be very important to testify the hypothesis of LGM carbon sequestration in the deep ocean. On the other hand, we can evaluate how the surface reservoir age and/or upwelling strength changed in

  14. Daily living skills in individuals with autism spectrum disorder from 2 to 21 years of age.

    PubMed

    Bal, Vanessa Hus; Kim, So-Hyun; Cheong, Daniel; Lord, Catherine

    2015-10-01

    Daily living skills (DLS), such as personal hygiene, meal preparation, and money management, are important to independent living. Research suggests that many individuals with autism spectrum disorder exhibit impairments in daily living skills relative to their cognitive skills. This study examined predictors of daily living skills attainment and trajectories of daily living skills in a longitudinal sample referred for possible autism spectrum disorder and followed from 2 to 21 years of age. Consistent with previous studies, participants with autism spectrum disorder and nonspectrum diagnoses showed continual development of daily living skills throughout childhood and adolescence. Early childhood nonverbal mental age was the strongest predictor of daily living skills attainment for both diagnostic groups. Group-based modeling suggested two distinct trajectories of daily living skills development for participants with autism spectrum disorder. Skill levels for both groups of young adults with autism spectrum disorder remained considerably below age level expectations. Whereas the "High-DLS" group gained approximately 12 years in daily living skills from T2 to T21, the "Low-DLS" group's daily living skills improved 3-4 years over the 16- to 19-year study period. Nonverbal mental age, receptive language, and social-communication impairment at 2 years predicted High- versus Low-DLS group membership. Receiving greater than 20 h of parent-implemented intervention before age 3 was also associated with daily living skills trajectory. Results suggest that daily living skills should be a focus of treatment plans for individuals with autism spectrum disorder, particularly adolescents transitioning to young adulthood.

  15. Asteroseismology for "à la carte" stellar age-dating and weighing. Age and mass of the CoRoT exoplanet host HD 52265

    NASA Astrophysics Data System (ADS)

    Lebreton, Y.; Goupil, M. J.

    2014-09-01

    Context. In the context of the space missions CoRoT, Kepler, Gaia, TESS, and PLATO, precise and accurate stellar ages, masses, and radii are of paramount importance. For instance, they are crucial for constraining scenarii of planetary formation and evolution. Aims: We aim at quantifying how detailed stellar modelling can improve the accuracy and precision on age and mass of individual stars. To that end, we adopt a multifaceted approach where we carefully examine how the number of observational constraints as well as the uncertainties on observations and on model input physics affect the results of age-dating and weighing. Methods: We modelled in detail the exoplanet host-star HD 52265, a main-sequence, solar-like oscillator that CoRoT observed for four months. We considered different sets of observational constraints (Hertzsprung-Russell data, metallicity, various sets of seismic constraints). For each case, we determined the age, mass, and properties of HD 52265 inferred from stellar models, and we quantified the impact of the model input physics and free parameters. We also compared model ages with ages derived by empirical methods or Hertzsprung-Russell diagram inversion. Results: For our case study HD 52265, our seismic analysis provides an age A = 2.10-2.54 Gyr, a mass M = 1.14-1.32 M⊙, and a radius R = 1.30-1.34 R⊙, which corresponds to age, mass, and radius uncertainties of ~10, ~7, and ~1.5 per cent, respectively. These uncertainties account for observational errors and current state-of-the-art stellar model uncertainties. Our seismic study also provides constraints on surface convection properties through the mixing-length, which we find to be 12-15 per cent lower than the solar value. On the other hand, because of helium-mass degeneracy, the initial helium abundance is determined modulo the mass value. Finally, we evaluate the seismic mass of the exoplanet to be Mpsini = 1.17-1.26 MJupiter, much more precise than what can be derived by Hertzsprung

  16. Collection, analysis, and age-dating of sediment cores from 56 U.S. lakes and reservoirs sampled by the U.S. Geological Survey, 1992-2001

    USGS Publications Warehouse

    Van Metre, Peter; Wilson, Jennifer T.; Fuller, Christopher C.; Callender, Edward; Mahler, Barbara J.

    2004-01-01

    The U.S. Geological Survey Reconstructed Trends National Synthesis study collected sediment cores from 56 lakes and reservoirs between 1992 and 2001 across the United States. Most of the sampling was conducted as part of the National Water-Quality Assessment (NAWQA) Program. The primary objective of the study was to determine trends in particle-associated contaminants in response to urbanization; 47 of the 56 lakes are in or near one of 20 U.S. cities. Sampling was done with gravity, piston, and box corers from boats and push cores from boats or by wading, depending on the depth of water and thickness of sediment being sampled. Chemical analyses included major and trace elements, organochlorine pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, cesium-137, and lead-210. Age-dating of the cores was done on the basis of radionuclide analyses and the position of the pre-reservoir land surface in the reservoir and, in a few cases, other chemical or lithologic depth-date markers. Dates were assigned in many cores on the basis of assumed constant mass accumulation between known depth-date markers. Dates assigned were supported using a variety of other date markers including first occurrence and peak concentrations of DDT and polychlorinated biphenyls and peak concentration of lead. A qualitative rating was assigned to each core on the basis of professional judgment to indicate the reliability of age assignments. A total of 122 cores were collected from the 56 lakes and age dates were assigned to 113 of them, representing 54 of the 56 lakes. Seventy-four of the 122 cores (61 percent) received a good rating for the assigned age dates, 28 cores (23 percent) a fair rating, and 11 cores (9 percent) a poor rating; nine cores (7 percent) had no dates assigned. An analysis of the influence of environmental factors on the apparent quality of age-dating of the cores concluded that the most important factor was the mass accumulation rate (MAR) of sediment: the

  17. Round-robin 230Th–234U age dating of bulk uranium for nuclear forensics

    SciTech Connect

    Gaffney, Amy M.; Hubert, Amélie; Kinman, William S.; Magara, Masaaki; Okubo, Ayako; Pointurier, Fabien; Schorzman, Kerri C.; Steiner, Robert E.; Williams, Ross W.

    2015-07-30

    In an inter-laboratory measurement comparison study, four laboratories determined 230Th–234U model ages of uranium certified reference material NBL U050 using isotope dilution mass spectrometry. The model dates determined by the participating laboratories range from 9 March 1956 to 19 October 1957, and are indistinguishable given the associated measurement uncertainties. As a result, these model ages are concordant with to slightly older than the known production age of NBL U050.

  18. 40K- 40Ar dating of the Main Deccan large igneous province: Further evidence of KTB age and short duration

    NASA Astrophysics Data System (ADS)

    Chenet, Anne-Lise; Quidelleur, Xavier; Fluteau, Frédéric; Courtillot, Vincent; Bajpai, Sunil

    2007-11-01

    Most mass extinctions coincide in time with outpourings of continental flood basalts (CFB). Some 20 years ago, it was shown [Courtillot, V., Besse, J., Vandamme, D., Montigny, R., Jaeger, J.-J., Cappetta, H., 1986. Deccan flood basalts at the Cretaceous/Tertiary boundary? Earth Planet. Sci. Lett. 80, 361-374; Courtillot, V., Feraud, G., Maluski, H., Vandamme, D., Moreau, M.G., Besse, J., 1988. Deccan flood basalts and the Cretaceous/Tertiary boundary. Nature 333, 843-846; Duncan, R.A., Pyle, D.G., 1988. Rapid eruption of the Deccan flood basalts at the Cretaceous/Tertiary boundary. Nature 333 841-843] that the age of the Deccan traps was close to the Cretaceous-Tertiary (KT) boundary and its duration under 1 Myr. We have undertaken a new geochronological study, using the (unconventional) 40K- 40Ar Cassignol-Gillot technique which is particularly well suited to the potassium-poor Deccan lavas. The mean of 4 determinations from the topmost (Ambenali and Mahabaleshwar) Formations is 64.5 ± 0.6 Ma. They straddle the C29r/C29n reversal boundary for which they provide a new constraint. The mean age of 3 determinations from the oldest (Jawhar) Formation is 64.8 ± 0.6 Ma. The difference in age between top and bottom of a 3500 m composite section, probably comprising 80% of the total Deccan volume, is statistically insignificant, with the overall mean age being 64.7 ± 0.6 Ma ( N = 7). Our results are consistent with the most recent 40Ar/ 39Ar determinations [Knight, K.B., Renne, P.R., Halkett, A., White, N., 2003. 40Ar/ 39Ar dating of the Rajahmundry Traps, eastern India and their relationship to the Deccan traps. Earth Planet. Sci. Lett. 208, 85-99; Knight, K.B., Renne, P.R., Baker, J., Waight, T., White, N., 2005. Reply to '40Ar/39Ar dating of the Rajahmundry Traps, Eastern India and their relationship to the Deccan Traps: Discussion' by A.K. Baksi. Earth Planet. Sci. Lett. 239, 374-382], confirming that there should be no systematic difference between the two methods

  19. Functional handwriting performance in school-age children with fetal alcohol spectrum disorders.

    PubMed

    Duval-White, Cherie J; Jirikowic, Tracy; Rios, Dianne; Deitz, Jean; Olson, Heather Carmichael

    2013-01-01

    Handwriting is a critical skill for school success. Children with fetal alcohol spectrum disorders (FASD) often present with fine motor and visual-motor impairments that can affect handwriting performance, yet handwriting skills have not been systematically investigated in this clinical group. This study aimed to comprehensively describe handwriting skills in 20 school-age children with FASD. Children were tested with the Process Assessment of the Learner, 2nd Edition (PAL-II), and the Visuomotor Precision subtest of NEPSY, a developmental neuropsychological assessment. Participants performed below average on PAL-II measures of handwriting legibility and speed and on NEPSY visual-motor precision tasks. In contrast, PAL-II measures of sensorimotor skills were broadly within the average range. Results provide evidence of functional handwriting challenges for children with FASD and suggest diminished visual-motor skills and increased difficulty as task complexity increases. Future research is needed to further describe the prevalence and nature of handwriting challenges in this population.

  20. 10Be dating reveals early-middle Holocene age of the Drygalski Moraines in central West Greenland

    NASA Astrophysics Data System (ADS)

    Cronauer, Sandra L.; Briner, Jason P.; Kelley, Samuel E.; Zimmerman, Susan R. H.; Morlighem, Mathieu

    2016-09-01

    We reconstruct the history of the Greenland Ice Sheet margin on the Nuussuaq Peninsula in central West Greenland through the Holocene using lake sediment analysis and cosmogenic 10Be exposure dating of the prominent Drygalski Moraines. Erratics perched on bedrock outboard of the Drygalski Moraines constrain local deglaciation to ∼9.9 ± 0.6 ka (n = 2). Three Drygalski Moraine crests yield mean 10Be ages of 8.6 ± 0.4 ka (n = 2), 8.5 ± 0.2 ka (n = 3), and 7.6 ± 0.1 ka (n = 2) from outer to inner. Perched erratics between the inner two moraines average 7.8 ± 0.1 ka (n = 2) and are consistent with the moraine ages. Sediments from a proglacial lake with a catchment area extending an estimated 2 km beneath (inland of) the present ice sheet terminus constrain an ice sheet minimum extent from 5.4 ka to 0.6 ka. The moraine chronology paired with the lake sediment stratigraphy reveals that the ice margin likely remained within ∼2 km of its present position from ∼9.9 to 5.4 ka. This unexpected early Holocene stability, preceded by rapid ice retreat and followed by minimum ice extent between ∼5.4 and 0.6 ka, contrasts with many records of early Holocene warmth and the Northern Hemisphere summer insolation maximum. We suggest ice margin stability may instead be tied to adjacent ocean temperatures, which reached an optimum in the middle Holocene.

  1. Age of the Druksiai-Polotsk deformation zone, Lithuania: a U-Pb dating of metamorphic titanite

    NASA Astrophysics Data System (ADS)

    Vejelyte, Irma; Bogdanova, Svetlana; Salnikova, Ekaterina

    2010-05-01

    The studied Druksiai-Polotsk deformation zone (DPDZ) transects the East Lithuanian Domain (ELD), representing the southern margin of the major Polotsk-Kurzeme zone of faulting in the Baltic-Belarus region. The DPDZ is of 35-40 km wide, E-W trending, and marked well by linear gravity and magnetic anomalies. The crystalline rocks within the DPDZ are granulites, biotite granites, and migmatites, the latter consisting of amphibole-plagioclase paleo- and mesosomes, and plagioclase-quartz-biotite±microcline±amphibole neosomes. Because of ductile shearing gneisses, augen mylonites, mylonites and ultramylonites were produced while tectonic breccias and pseudotachyllite were formed by later brittle deformation. According to geophysical data and the surface morphology of the crystalline basement, a horst-graben structure have recognized along the DPDZ. The graben is filled with Vendian, Cambrian, Ordovician, Silurian and Devonian deposits. A U-Pb dating of titanite from an augen granitoid mylonite in the DPDZ has yielded a concordant age of 1534±9 Ma. This light brown titanite follows the folation in the host rock and was obviously formed during retrogression from amphibolite- to epidote-amphibolite facies and coeval mylonitization. Shear zones of the same age are known in southern and central Sweden and in NE Poland. These E-W trending deformation zones accommodate both mafic and granitoid intrusions and are probably related to an extensional period in the Mesoproterozoic evolution in the western part of the East European Craton. This is a contribution to the project "The Precambrian structure of Baltica as a control of its recent environment and evolution" of the Visby Programme supported by the Swedish Institute and the Lithuanian State Science and Studies Foundation.

  2. Age Related Differences of Executive Functioning Problems in Everyday Life of Children and Adolescents in the Autism Spectrum

    ERIC Educational Resources Information Center

    van den Bergh, Sanne F. W. M.; Scheeren, Anke M.; Begeer, Sander; Koot, Hans M.; Geurts, Hilde M.

    2014-01-01

    Numerous studies investigated executive functioning (EF) problems in people with autism spectrum disorders (ASD) using laboratory EF tasks. As laboratory task performances often differ from real life observations, the current study focused on EF in everyday life of 118 children and adolescents with ASD (6-18 years). We investigated age-related and…

  3. Pilot Study Measuring the Effects of Therapeutic Horseback Riding on School-Age Children and Adolescents with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Gabriels, Robin L.; Agnew, John A.; Holt, Katherine D.; Shoffner, Amy; Zhaoxing, Pan; Ruzzano, Selga; Clayton, Gerald H.; Mesibov, Gary

    2012-01-01

    This preliminary study examined the effects of 10 weekly lessons of therapeutic horseback riding (THR) on 42 participants diagnosed with an autism spectrum disorder (ages 6-16 years) compared to a subset (n=16) of the total study population who were first evaluated before and after a 10-week waitlist control condition. All participants received…

  4. Advanced Parental Ages and Low Birth Weight in Autism Spectrum Disorders--Rates and Effect on Functioning

    ERIC Educational Resources Information Center

    Ben Itzchak, Esther; Lahat, Eli; Zachor, Ditza A.

    2011-01-01

    Objectives: (1) To assess the distribution of parental age and birth weight in a large cohort with autism spectrum disorder (ASD) and to compare them to Israeli national data. (2) To examine possible relationships between these risk factors and functioning. Methods: The study included 529 participants diagnosed with ASD using standardized tests:…

  5. Early Indicators of Autism Spectrum Disorders at 12 and 24 Months of Age: A Prospective, Longitudinal Comparative Study

    ERIC Educational Resources Information Center

    Veness, Carly; Prior, Margot; Bavin, Edith; Eadie, Patricia; Cini, Eileen; Reilly, Sheena

    2012-01-01

    Prospective questionnaire data from a longitudinal population sample on children with autism spectrum disorders (ASD), developmental delay, specific language impairment, or typical development (TD), were collected at ages eight, 12 and 24 months, via the Communication and Symbolic Behavior Scale Developmental Profile (CSBS)--Infant Toddler…

  6. Disparity in Autism Spectrum Disorder Prevalence among Taiwan National Health Insurance Enrollees: Age, Gender and Urbanization Effects

    ERIC Educational Resources Information Center

    Hsu, Shang-Wei; Chiang, Po-Huang; Lin, Lam-Ping; Lin, Jin-Ding

    2012-01-01

    The present study aims to characterize the prevalence of autism spectrum disorders (ASDs) in Taiwan while examining the effects of age, gender, and urbanization on ASD occurrence. A cross-sectional study was conducted to analyze data from 895,639 random health insurance claimants who claimed medical services in the year 2007. Autism was defined…

  7. Brief Report: Impaired Flexible Item Selection Task (FIST) in School-Age Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Yerys, Benjamin E.; Wolff, Brian C.; Moody, Eric; Pennington, Bruce F.; Hepburn, Susan L.

    2012-01-01

    Cognitive flexibility has been measured with inductive reasoning or explicit rule tasks in individuals with autism spectrum disorders (ASD). The "Flexible Item Selection Task" (FIST) differs from previous cognitive flexibility tasks in ASD research by giving children an abstract, ambiguous rule to switch. The ASD group (N = 22; Mean age = 8.28…

  8. Comparison of Conditioning Impairments in Children with Down Syndrome, Autistic Spectrum Disorders and Mental Age-Matched Controls

    ERIC Educational Resources Information Center

    Reed, P.; Staytom, L.; Stott, S.; Truzoli, R.

    2011-01-01

    Background: This study investigated the relative ease of learning across four tasks suggested by an adaptation of Thomas's hierarchy of learning in children with Down syndrome, autism spectrum disorders and mental age-matched controls. Methods: Learning trials were carried out to investigate observational learning, instrumental learning, reversal…

  9. Brief Report: Ages of Language Milestones as Predictors of Developmental Trajectories in Young Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Kover, Sara T.; Edmunds, Sarah R.; Ellis Weismer, Susan

    2016-01-01

    Recognizing early risk markers in young children with autism spectrum disorder (ASD) is critical for timely diagnosis and intervention. The purpose of this study was to extend previous findings regarding language milestones to a longitudinal design, in which ages of expressive language milestones (i.e., first words, first phrases) could serve as…

  10. Parsing Heterogeneity in Autism Spectrum Disorders: Visual Scanning of Dynamic Social Scenes in School-Aged Children

    ERIC Educational Resources Information Center

    Rice, Katherine; Moriuchi, Jennifer M.; Jones, Warren; Klin, Ami

    2012-01-01

    Objective: To examine patterns of variability in social visual engagement and their relationship to standardized measures of social disability in a heterogeneous sample of school-aged children with autism spectrum disorders (ASD). Method: Eye-tracking measures of visual fixation during free-viewing of dynamic social scenes were obtained for 109…

  11. Geochemical analyses, age dates, and flow-volume estimates for quaternary volcanic rocks, Southern Cascade Mountains, Washington

    SciTech Connect

    Hammond, P.E.; Korosec, M.A.

    1983-12-01

    Data collected over the last three years as part of a continuing study of the Quaternary volcanic rocks of the southern Cascade Mountains are presented. Whole-rock chemical analyses, selected trace element geochemistry, volume approximations, specific gravity determinations, and locations are provided for most of the 103 samples collected, and 21 radiometric age dates are included. In addition, partial information, including names and flow-volumes, are presented for 98 additional samples, collected for related studies. The study extends from the Columbia River north to the Cowlitz River and Goat Rocks Wilderness area, and from the Klickitat River west to the Puget-Willamette Trough. The volcanic rocks are all younger than 3 million years and consist primarily of tholeiitic and high-alumina basalts and basaltic-andesites erupted from numerous shield volcanoes and cinder cones. A few analyses of more silicic rocks, including hornblende and/or pyroxene andesites and dacites characteristic of the stratovolcanoes of the region, are also presented. However, systematic sampling of the stratovolcanoes in the study area, Mount Adams and Mount St. Helens, was not conducted. A map of the areal extent of Quaternary volcanic units and sample locations is included. It has been based on the 1:125,000 reconnaissance geologic map of the southern Cascade Range by Hammond (1980).

  12. Geochemical analyses, age dates, and flow-volume estimates for quaternary volcanic rocks, Southern Cascade Mountains, Washington

    NASA Astrophysics Data System (ADS)

    Hammond, P. E.; Korosec, M. A.

    1983-12-01

    Data collected over the last three years as part of a continuing study of the Quaternary volcanic rocks of the southern Cascade Mountains are presented. Whole-rock chemical analyses, selected trace element geochemistry, volume approximations, specific gravity determinations, and locations are provided for most of the 103 samples collected, and 21 radiometric age dates are included. In addition, partial information, including names and flow-volumes, are presented for 98 additional samples, collected for related studies. The study extends from the Columbia River north to the Cowlitz River and Goat Rocks Wilderness area, and from the Klickitat River west to the Puget-Williamette Trough. The volcanic rocks are all younger than 3 million years and consist primarily of tholeitic and high-alumina basalts and basaltic-andesites erupted from numerous shield volcanoes and cinder cones. A few analyses of more silicic rocks, including hornblende and/or pyroxene andesites and dacites characteristic of the stratovolcanoes of the region, are also presented.

  13. MRI with ferumoxytol: A single center experience of safety across the age spectrum

    PubMed Central

    Nguyen, Kim‐Lien; Yoshida, Takegawa; Han, Fei; Ayad, Ihab; Reemtsen, Brian L.; Salusky, Isidro B.; Satou, Gary M.; Hu, Peng

    2016-01-01

    Purpose To summarize our single‐center safety experience with the off‐label use of ferumoxytol for magnetic resonance imaging (MRI) and to compare the effects of ferumoxytol on monitored physiologic indices in patients under anesthesia with those of gadofosveset trisodium. Materials and Methods Consecutive patients who underwent ferumoxytol‐enhanced (FE) MRI exams were included. Adverse events (AEs) were classified according to the Common Terminology Criteria for Adverse Events v4.0. In a subgroup of patients examined under general anesthesia, recording of blood pressure, heart rate, oxygen saturation, and end‐tidal CO2 was performed. A comparable group of 23 patients who underwent gadofosveset‐enhanced (GE) MRI under anesthesia with similar monitoring was also analyzed. Results In all, 217 unique patients, ages 3 days to 94 years, underwent FE‐MRI. No ferumoxytol‐related severe, life‐threatening, or fatal AEs occurred acutely or at follow‐up. Two patients developed ferumoxytol‐related nausea. Between‐group (FE‐ vs. GE‐MRI) comparisons showed no statistical difference in heart rate (P = 0.69, 95% confidence interval [CI] 96–113 bpm), mean arterial blood pressure (MAP) (P = 0.74, 95% CI 44–52 mmHg), oxygen saturation (P = 0.76, 95% CI 94–98%), and end‐tidal CO2 (P = 0.73, 95% CI 31–37 mmHg). No significant change in MAP (P = 0.12, 95% CI 50–58 mmHg) or heart rate (P = 0.25, 95% CI 91–105 bpm) was noted between slow infusion of ferumoxytol (n = 113) vs. bolus injection (n = 104). Conclusion In our single‐center experience, no serious AEs occurred with the diagnostic use of ferumoxytol across a wide spectrum of age, renal function, and indications. Because of the limited sample size, firm conclusions cannot be drawn about the generalizability of our results. Thus, vigilance and monitoring are recommended to mitigate potential rare adverse reactions. Level of Evidence: 2 J. Magn. Reson. Imaging

  14. Bayesian methods applied to the interpretation of multiple OSL dates: high precision sediment ages from Old Scatness Broch excavations, Shetland Isles

    NASA Astrophysics Data System (ADS)

    Rhodes, E. J.; Bronk Ramsey, C.; Outram, Z.; Batt, C.; Willis, L.; Dockrill, S.; Bond, J.

    2003-05-01

    In this paper, we illustrate the ways in which Bayesian statistical techniques may be used to enhance chronological resolution when applied to a series of OSL sediment dates. Such application can achieve an optimal chronological model by incorporating stratigraphic and age information. The application to luminescence data is not straightforward owing to the sources of uncertainty in each date, and here we present one solution to overcoming these difficulties, and introduce the concept of "unshared systematic" errors. Using OSL sediment dates from the site of Old Scatness Broch, Shetland Isles, UK, many measured with a high degree of precision, we illustrate some of the ways in which Bayesian techniques may be applied, as a tool for assessing systematic errors when combined with independent chronological information, and to determine the optimum chronological information for specific events and contexts. We provide a detailed procedure for the application of Bayesian methods to OSL dates using the widely available radiocarbon calibration programme OxCal.

  15. An extended magnetic viscous relaxation dating for calibrating an older age: an example of tsunamigenic coral boulders in Ishigaki Island, Japan

    NASA Astrophysics Data System (ADS)

    Sato, T.; Nakamura, N.; Goto, K.; Kumagai, Y.; Minoura, K.; Nagahama, H.

    2015-12-01

    A key to the understanding of past tsunami events is the ability to accurately date them. Analysis of past tsunami sediments is one of the most important tools for past tsunami reconstruction. A typical example of such tsunami sediment is tsunamigenic boulders. In Ishigaki Island, Japan, coral boulders that had been transported by tsunamis were distributed on the beach and land areas. Although the historical occurrences of several huge tsunamis were estimated based on large numbers of radiocarbon dating for coral boulders, radiocarbon dating can not determine a multiple rotational history by multiple tsunamis. A viscous remanet magnetization (VRM) dating method can be used to date any geological event that results in significant movements of a rock. Sato et al. (2014) applied VRM dating for comparing the radiocarbon age of these boulders. If a magnetic-mineral bearing rock is moved or re-oriented, the magnetism of the smaller magnetic grains re-aligns to the direction of the ambient magnetic field with time. This phenomenon is well known as Néel's (1949, 1955) single-domain (SD) relaxation theory. Pullaiah et al. (1975) derived a time-temperature (t-T relation) relation by assuming Néel's (1949, 1955) theory of magnetite. In principle, an experimental combination of short relaxation time and high temperature for removing VRM can determine the unknown relaxation time (tsunami age) at room temperature. We have been applied t-T relation to the coral boulders on Ishigaki Island, but their estimated ages showed older than radiocarbon dating. The longer relaxation time means that the observed magnetic relaxation is slower than the original Néel's theory. Such slow relaxation has been described by a stretched exponential function. The stretched exponential law provided a reasonable fit to the published experimental data. Thus, in this study, we revisit Néel's theory to provide a new t-T relation based on stretched exponential function.

  16. Aging of target lipid parameters in fingermark residue using GC/MS: Effects of influence factors and perspectives for dating purposes.

    PubMed

    Girod, Aline; Spyratou, Alexandra; Holmes, David; Weyermann, Céline

    2016-05-01

    Despite the recurrence of fingermark dating issues and the research conducted on fingermark composition and aging, no dating methodology has yet been developed and validated. In order to further evaluate the possibility of developing dating methodologies based on the fingermark composition, this research proposed an in-depth study of the aging of target lipid parameters found in fingermark residue and exposed to different influence factors. The selected analytical technique was gas chromatography coupled with mass spectrometry (GC/MS). The effects of donor, substrate and enhancement techniques on the selected parameters were firstly evaluated. These factors were called known factors, as their value could be obtained in real caseworks. Using principal component analysis (PCA) and univariate exponential regression, this study highlighted the fact that the effects of these factors were larger than the aging effects, thus preventing the observation of relevant aging patterns. From a fingermark dating perspective, the specific value of these known factors should thus be included in aging models newly built for each case. Then, the effects of deposition moment, pressure, temperature and lighting were also evaluated. These factors were called unknown factors, as their specific value would never be precisely obtained in caseworks. Aging models should thus be particularly robust to their effects and for this reason, different chemometric tools were tested: PCA, univariate exponential regression and partial least square regression (PLSR). While the first two models allowed observing interesting aging patterns regardless of the value of the applied influence factors, PLSR gave poorer results, as large deviations were obtained. Finally, in order to evaluate the potential of such modelling in realistic situations, blind analyses were carried out on eight test fingermarks. The age of five of them was correctly estimated using soft independent modelling of class analogy analysis

  17. Psychiatric Co-occurring Symptoms and Disorders in Young, Middle-Aged, and Older Adults with Autism Spectrum Disorder.

    PubMed

    Lever, Anne G; Geurts, Hilde M

    2016-06-01

    Although psychiatric problems are less prevalent in old age within the general population, it is largely unknown whether this extends to individuals with autism spectrum disorders (ASD). We examined psychiatric symptoms and disorders in young, middle-aged, and older adults with and without ASD (Nmax = 344, age 19-79 years, IQ > 80). Albeit comparable to other psychiatric patients, levels of symptoms and psychological distress were high over the adult lifespan; 79 % met criteria for a psychiatric disorder at least once in their lives. Depression and anxiety were most common. However, older adults less often met criteria for any psychiatric diagnosis and, specifically, social phobia than younger adults. Hence, despite marked psychological distress, psychiatric problems are also less prevalent in older aged individuals with ASD.

  18. The effect of age, sex and clinical features on the volume of Corpus Callosum in pre-schoolers with Autism Spectrum Disorder: a case-control study.

    PubMed

    Giuliano, Alessia; Saviozzi, Irene; Brambilla, Paolo; Muratori, Filippo; Retico, Alessandra; Calderoni, Sara

    2017-01-23

    A growing body of literature has identified volume alterations of the corpus callosum (CC) in subjects with autism spectrum disorders (ASD). However, to date very few investigations have been conducted on pre-school-age ASD children. This study aims to compare the volume of CC and its sub-regions between pre-schoolers with ASD and controls (CON) and to examine their relationship to demographic and clinical variables (sex, age, non-verbal IQ -NVIQ-, expressive non-echolalic language, emotional and behavioural problems, and autism severity). The volume of CC of 40 pre-schoolers with ASD (20 males and 20 females; mean age: 49 ± 12 months; mean NVIQ: 73 ± 22) and 40 sex-, age-, and NVIQ-matched CON subjects (20 M and 20 F; mean age: 49 ± 14 months; mean NVIQ: 73 ± 23) were quantified applying the FreeSurfer automated parcellation software on Magnetic Resonance images. No significant volumetric differences in CC total volume and in its sub-regions between ASD and CON were found using total brain volume as a covariate. Analogously, absence of CC volumetric differences was evident when boys and girls with ASD were compared with their matched controls. The CC total volume of younger ASD male subjects was found significantly larger with respect to matched CON, which is consistent with the atypical growth trajectory widely reported in these young children. The CC total volume was negatively correlated with autism severity, whereas no association between CC volume and other clinical variables was detected. If replicated, the indirect relationship between CC volume and autism severity suggests the involvement of CC in core ASD symptoms.

  19. The Influence of Gender, Age, Psychological Resilience and Family Interaction Factors upon Anxiety and Depression in Non-Autism Spectrum Disorder Siblings of Children with an Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Bitsika, Vicki; Sharpley, Christopher F.; Mailli, Rebecca

    2015-01-01

    The influence of gender, age, Psychological resilience and family interaction factors upon generalised anxiety disorder (GAD) and major depressive disorder (MDD) was investigated in 75 non-autism spectrum disorder (NASD) siblings who had a brother or sister with an autism spectrum disorder (ASD). GAD and MDD were much more prevalent than in…

  20. Resolving the age of Wilson Creek Formation tephras and the Mono Lake excursion using high-resolution SIMS dating of allanite and zircon rims

    NASA Astrophysics Data System (ADS)

    Vazquez, J. A.; Lidzbarski, M. I.

    2012-12-01

    Sediments of the Wilson Creek Formation surrounding Mono Lake preserve a high-resolution archive of glacial and pluvial responses along the eastern Sierra Nevada due to late Pleistocene climate change. An absolute chronology for the Wilson Creek stratigraphy is critical for correlating the paleoclimate record to other archives in the western U.S. and the North Atlantic region. However, multiple attempts to date the Wilson Creek stratigraphy using carbonates and interbedded rhyolitic tephras yield discordant 14C and 40Ar/39Ar results due to open-system effects, carbon reservoir uncertainties, as well as abundant xenocrysts entrained during eruption. Ion microprobe (SIMS) 238U-230Th dating of the final increments of crystallization recorded by allanite and zircon autocrysts from juvenile pyroclasts yields ages that effectively date eruption of key tephra beds and resolve age uncertainties about the Wilson Creek stratigraphy. To date the final several micrometers of crystal growth, individual allanite and zircon crystals were embedded in soft indium to allow sampling of unpolished rims. Isochron ages derived from rims on coexisting allanite and zircon (± glass) from hand-selected pumiceous pyroclasts delimit the timing of Wilson Creek sedimentation between Ashes 7 and 19 (numbering of Lajoie, 1968) to the interval between ca. 27 to ca. 62 ka. The interiors of individual allanite and zircon crystals sectioned in standard SIMS mounts yield model 238U-230Th ages that are mostly <10 k.y. older than their corresponding rim age, suggesting a relatively brief interval of allanite + zircon crystallization before eruption. A minority of allanite and zircon crystals yield rim and interior model ages of ca. 90-100 ka, and are likely to be antecrysts recycled from relatively early Mono Craters volcanism and/or intrusions. Tephra (Ash 15) erupted during the geomagnetic excursion originally designated the Mono Lake excursion yields a rim isochron age of ca. 41 ka indicating that

  1. Aging Wire Insulation Assessment by Phase Spectrum Examination of Ultrasonic Guided Waves

    NASA Technical Reports Server (NTRS)

    Anastasi, Robert F.; Madaras, Eric I.

    2003-01-01

    Wire integrity has become an area of concern to the aerospace community including DoD, NASA, FAA, and Industry. Over time and changing environmental conditions, wire insulation can become brittle and crack. The cracks expose the wire conductor and can be a source of equipment failure, short circuits, smoke, and fire. The technique of using the ultrasonic phase spectrum to extract material properties of the insulation is being examined. Ultrasonic guided waves will propagate in both the wire conductor and insulation. Assuming the condition of the conductor remains constant then the stiffness of the insulator can be determined by measuring the ultrasonic guided wave velocity. In the phase spectrum method the guided wave velocity is obtained by transforming the time base waveform to the frequency domain and taking the phase difference between two waveforms. The result can then be correlated with a database, derived by numerical model calculations, to extract material properties of the wire insulator. Initial laboratory tests were performed on a simple model consisting of a solid cylinder and then a solid cylinder with a polymer coating. For each sample the flexural mode waveform was identified. That waveform was then transformed to the frequency domain and a phase spectrum was calculated from a pair of waveforms. Experimental results on the simple model compared well to numerical calculations. Further tests were conducted on aircraft or mil-spec wire samples, to see if changes in wire insulation stiffness can be extracted using the phase spectrum technique.

  2. Stress for Individuals with Autism Spectrum Disorders: Effects of Age, Gender, and Intelligence Quotient

    ERIC Educational Resources Information Center

    Hess, Kristen Louise

    2009-01-01

    Researchers previously have found that individuals with Autism Spectrum Disorders (ASD) experience higher levels of stress and anxiety than individuals who are typically developing and than those with other disabilities. The purpose of this study was to identify the nature and degree of stress reported for individuals with ASD, with particular…

  3. Validation of the Pictorial Infant Communication Scale for Preschool-Aged Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Ghilain, Christine S.; Parlade, Meaghan V.; McBee, Matthew T.; Coman, Drew C.; Owen, Taylor; Gutierrez, Anibal; Boyd, Brian; Odom, Samuel; Alessandri, Michael

    2017-01-01

    Joint attention, or the shared focus of attention between objects or events and a social partner, is a crucial milestone in the development of social communication and a notable area of deficit in children with autism spectrum disorder. While valid parent-report screening measures of social communication are available, the majority of these…

  4. Daily Living Skills in Individuals with Autism Spectrum Disorder from 2 to 21?Years of Age

    ERIC Educational Resources Information Center

    Bal, Vanessa Hus; Kim, So-Hyun; Cheong, Daniel; Lord, Catherine

    2015-01-01

    Daily living skills (DLS), such as personal hygiene, meal preparation, and money management, are important to independent living. Research suggests that many individuals with autism spectrum disorder exhibit impairments in daily living skills relative to their cognitive skills. This study examined predictors of daily living skills attainment and…

  5. Nonverbal and Verbal Cognitive Discrepancy Profiles in Autism Spectrum Disorders: Influence of Age and Gender

    ERIC Educational Resources Information Center

    Ankenman, Katy; Elgin, Jenna; Sullivan, Katherine; Vincent, Logan; Bernier, Raphael

    2014-01-01

    Research suggests that discrepant cognitive abilities are more common in children with autism spectrum disorder (ASD) and may indicate an important ASD endophenotype. The current study examined the frequency of IQ discrepancy profiles (nonverbal IQ greater than verbal IQ [NVIQ greater than VIQ], verbal IQ greater than nonverbal IQ [VIQ greater…

  6. Preparing Transition-Age Students with High-Functioning Autism Spectrum Disorders for Meaningful Work

    ERIC Educational Resources Information Center

    Lee, Gloria K.; Carter, Erik W.

    2012-01-01

    This article provides an overview of promising essential elements for fostering vocational success among students with high-functioning autism spectrum disorders (HFASDs) by drawing literature from the fields of school-to-work transition for post-secondary students and vocational rehabilitation for individuals with disabilities. We highlight seven…

  7. Age of the Lava Creek supereruption and magma chamber assembly at Yellowstone based on 40Ar/39Ar and U-Pb dating of sanidine and zircon crystals

    USGS Publications Warehouse

    Matthews, Naomi E.; Vazquez, Jorge A.; Calvert, Andrew T.

    2015-01-01

    The last supereruption from the Yellowstone Plateau formed Yellowstone caldera and ejected the >1000 km3 of rhyolite that composes the Lava Creek Tuff. Tephra from the Lava Creek eruption is a key Quaternary chronostratigraphic marker, in particular for dating the deposition of mid Pleistocene glacial and pluvial deposits in western North America. To resolve the timing of eruption and crystallization history for the Lava Creek magma, we performed (1) 40Ar/39Ar dating of single sanidine crystals to delimit eruption age and (2) ion microprobe U-Pb and trace-element analyses of the crystal faces and interiors of single zircons to date the interval of zircon crystallization and characterize magmatic evolution. Sanidines from the two informal members composing Lava Creek Tuff yield a preferred 40Ar/39Ar isochron date of 631.3 ± 4.3 ka. Crystal faces on zircons from both members yield a weighted mean 206Pb/238U date of 626.5 ± 5.8 ka, and have trace element concentrations that vary with the eruptive stratigraphy. Zircon interiors yield a mean 206Pb/238U date of 659.8 ± 5.5 ka, and reveal reverse and/or oscillatory zoning of trace element concentrations, with many crystals containing high U concentration cores that likely grew from highly evolved melt. The occurrence of distal Lava Creek tephra in stratigraphic sequences marking the Marine Isotope Stage 16–15 transition supports the apparent eruption age of ∼631 ka. The combined results reveal that Lava Creek zircons record episodic heating, renewed crystallization, and an overall up-temperature evolution for Yellowstone's subvolcanic reservoir in the 103−104 year interval before eruption.

  8. Radiometric Dating Does Work!

    ERIC Educational Resources Information Center

    Dalrymple, G. Brent

    2000-01-01

    Discusses the accuracy of dating methods and creationist arguments that radiometric dating does not work. Explains the Manson meteorite impact and the Pierre shale, the ages of meteorites, the K-T tektites, and dating the Mount Vesuvius eruption. (Author/YDS)

  9. Potential for timing high-energy marine inundation events in the recent geological past through age-dating of reef boulders in Fiji

    NASA Astrophysics Data System (ADS)

    Terry, James P.; Etienne, Samuel

    2014-12-01

    Transported coastal boulders have increasingly come to represent a valuable element of investigations within the broader framework of multi-proxy approaches applied to coastal hazard studies. Through a case study on Taveuni Island in Fiji, this paper outlines some approaches and hindrances to effective timing of prehistorical high-energy marine inundation events (storms and tsunamis) on tropical coastlines from the evidence of reef-platform carbonate boulders. Various sources of errors are outlined that investigators must consider when attempting to use carbonate boulder ages as a surrogate for timing past events. On Taveuni, uranium : thorium dates with a high level of precision (1-7 years) suggest that major inundation events have a return period of approximately 40-45 years since 1650 AD. Of particular importance, considerably different age dates are provided by coral samples sourced from the top and bottom (i.e. opposite faces) of individual boulders, so highlighting interpretation biases that must be avoided.

  10. Aging

    PubMed Central

    Park, Dong Choon

    2013-01-01

    Aging is initiated based on genetic and environmental factors that operate from the time of birth of organisms. Aging induces physiological phenomena such as reduction of cell counts, deterioration of tissue proteins, tissue atrophy, a decrease of the metabolic rate, reduction of body fluids, and calcium metabolism abnormalities, with final progression onto pathological aging. Despite the efforts from many researchers, the progression and the mechanisms of aging are not clearly understood yet. Therefore, the authors would like to introduce several theories which have gained attentions among the published theories up to date; genetic program theory, wear-and-tear theory, telomere theory, endocrine theory, DNA damage hypothesis, error catastrophe theory, the rate of living theory, mitochondrial theory, and free radical theory. Although there have been many studies that have tried to prevent aging and prolong life, here we introduce a couple of theories which have been proven more or less; food, exercise, and diet restriction. PMID:24653904

  11. Ultra-high precision 40Ar/39Ar ages for Fish Canyon Tuff and Alder Creek Rhyolite sanidine: New dating standards required?

    NASA Astrophysics Data System (ADS)

    Phillips, D.; Matchan, E. L.

    2013-11-01

    The 40Ar/39Ar dating technique is a high precision (<0.1%) method with wide application to geological samples. However, the method is predicated on the availability of natural mineral standards of known age. Widely used 40Ar/39Ar standards include sanidine from the (ca. 28 Ma) Fish Canyon Tuff (FCT) and the (ca. 1.2 Ma) Alder Creek Rhyolite (ACR). Despite common usage, the ages of FCT and ACR sanidine have proven contentious, with reported values varying by >2%; well outside the ±0.1% aspiration of EARTHTIME (http://www.earth-time.org).

  12. Age determination of nephrite by in-situ SIMS U-Pb dating syngenetic titanite: A case study of the nephrite deposit from Luanchuan, Henan, China

    NASA Astrophysics Data System (ADS)

    Ling, Xiao-Xiao; Schmädicke, Esther; Li, Qiu-Li; Gose, Jürgen; Wu, Rui-Hua; Wang, Shi-Qi; Liu, Yu; Tang, Guo-Qiang; Li, Xian-Hua

    2015-04-01

    Nephrite is a kind of valuable jade which forms during metamorphism under greenschist facies conditions. Most investigations focus on the genesis of nephrite, however, the formation age of nephrite remains poorly constrained due to the lack of suitable dating methods. In this paper, the petrological, chemical characteristics, and mineral inclusions of nephrite collected from Luanchuan, Henan, China have been studied by optical and electron microscopy and wavelength-dispersive electron microprobe (EMP). The petrological observations show that nephrite consists mainly of tremolite, minor calcite and titanite, occasionally with rutile, quartz, serpentine, chlorite, pyrite, and apatite. The titanite and tremolite which are intergrown with each other share low-energy grain boundaries. It indicates that the two phases are equilibrated and can be considered as cogenetic. The chemical composition of tremolite is high in Si, Mg, Ca, but low in Fe, Cr, and Ni, which indicates that the nephrite from Luanchuan belongs to the dolomite type rather than the serpentinite type. The petrography of different nephrite structures suggests that the grain size of tremolite was determined by the stress intensity undergone during the nephrite formation progress. In-situ Secondary Ion Mass Spectrometer (SIMS) U-Pb dating of titanite from nephrite yielded an age of 361 ± 4 Ma, which is the first estimate for the time of formation of the Luanchuan nephrite deposit. This investigation provides a powerful in-situ dating method to unravel the age of nephrite, which could be served as a tool for future research on other nephrite deposits.

  13. In situ SIMS U-Pb dating of hydrothermal rutile: reliable age for the Zhesang Carlin-type gold deposit in the golden triangle region, SW China

    NASA Astrophysics Data System (ADS)

    Pi, Qiaohui; Hu, Ruizhong; Xiong, Bin; Li, Qiuli; Zhong, Richen

    2017-02-01

    The contiguous region between Guangxi, Guizhou, and Yunnan, commonly referred to as the Golden Triangle region in SW China, hosts many Carlin-type gold deposits. Previously, the ages of the gold mineralization in this region have not been well constrained due to the lack of suitable minerals for radiometric dating. This paper reports the first SIMS U-Pb age of hydrothermal rutile crystals for the Zhesang Carlin-type gold deposit in the region. The hydrothermal U-bearing rutile associated with gold-bearing sulfides in the deposit yields an U-Pb age of 213.6 ± 5.4 Ma, which is within the range of the previously reported arsenopyrite Re-Os isochron ages (204 ± 19 to 235 ± 33 Ma) for three other Carlin-type gold deposits in the region. Our new and more precise rutile U-Pb age confirms that the gold mineralization was contemporaneous with the Triassic W-Sn mineralization and associated granitic magmatism in the surrounding regions. Based on the temporal correlation, we postulate that coeval granitic plutons may be present at greater depths in the Golden Triangle region and that the formation of the Carlin-type gold deposits is probably linked to the coeval granitic magmatism in the region. This study clearly demonstrates that in situ rutile U-Pb dating is a robust tool for the geochronogical study of hydrothermal deposits that contain hydrothermal rutile.

  14. Motor Skills in Children Aged 7-10 Years, Diagnosed with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Whyatt, Caroline P.; Craig, Cathy M.

    2012-01-01

    This study used the Movement Assessment Battery for Children (M-ABC2) to assess motor skills in children aged 7-10 years with autism (n = 18) in comparison to two groups of age-matched typically developing children; a receptive vocabulary matched group (n = 19) and a nonverbal IQ matched group (n = 22). The results supported previous work, as…

  15. No Relative Age Effect in the Birth Dates of Award-Winning Athletes in Male Professional Team Sports

    ERIC Educational Resources Information Center

    Ford, Paul R.; Williams, A. Mark

    2011-01-01

    Athletes born early within an annual youth age-group selection year are probably more likely to be selected for sports teams and talent development programs than those born later in that year. Overrepresentation of these relatively older athletes in youth and adult sport is known as the relative age effect (RAE). RAEs were found in these popular…

  16. Using an independent geochronology based on palaeomagnetic secular variation (PSV) and atmospheric Pb deposition to date Baltic Sea sediments and infer 14C reservoir age

    NASA Astrophysics Data System (ADS)

    Lougheed, Bryan C.; Snowball, Ian; Moros, Matthias; Kabel, Karoline; Muscheler, Raimund; Virtasalo, Joonas J.; Wacker, Lukas

    2012-05-01

    Dating of sediment cores from the Baltic Sea has proven to be difficult due to uncertainties surrounding the 14C reservoir age and a scarcity of macrofossils suitable for dating. Here we present the results of multiple dating methods carried out on cores in the Gotland Deep area of the Baltic Sea. Particular emphasis is placed on the Littorina stage (8 ka ago to the present) of the Baltic Sea and possible changes in the 14C reservoir age of our dated samples. Three geochronological methods are used. Firstly, palaeomagnetic secular variations (PSV) are reconstructed, whereby ages are transferred to PSV features through comparison with varved lake sediment based PSV records. Secondly, lead (Pb) content and stable isotope analysis are used to identify past peaks in anthropogenic atmospheric Pb pollution. Lastly, 14C determinations were carried out on benthic foraminifera (Elphidium spec.) samples from the brackish Littorina stage of the Baltic Sea. Determinations carried out on smaller samples (as low as 4 μg C) employed an experimental, state-of-the-art method involving the direct measurement of CO2 from samples by a gas ion source without the need for a graphitisation step - the first time this method has been performed on foraminifera in an applied study. The PSV chronology, based on the uppermost Littorina stage sediments, produced ten age constraints between 6.29 and 1.29 cal ka BP, and the Pb depositional analysis produced two age constraints associated with the Medieval pollution peak. Analysis of PSV data shows that adequate directional data can be derived from both the present Littorina saline phase muds and Baltic Ice Lake stage varved glacial sediments. Ferrimagnetic iron sulphides, most likely authigenic greigite (Fe3S4), present in the intermediate Ancylus Lake freshwater stage sediments acquire a gyroremanent magnetisation during static alternating field (AF) demagnetisation, preventing the identification of a primary natural remanent magnetisation for

  17. A State of Double Jeopardy: Impact of Prenatal Alcohol Exposure and Adverse Environments on the Social Communicative Abilities of School-Age Children with Fetal Alcohol Spectrum Disorder

    ERIC Educational Resources Information Center

    Coggins, Truman E.; Timler, Geralyn R.; Olswang, Lesley B.

    2007-01-01

    Purpose: This article is a retrospective examination of environmental risk, language performance, and narrative discourse data from a clinical database of school-age children with fetal alcohol spectrum disorder (FASD). Method: A case-defined diagnostic approach for measuring and reporting the full spectrum of disabilities in children with…

  18. Stability and Change in Autism Spectrum Disorder Diagnosis from Age 3 to Middle Childhood in a High-Risk Sibling Cohort

    ERIC Educational Resources Information Center

    Brian, Jessica; Bryson, Susan E.; Smith, Isabel M.; Roberts, Wendy; Roncadin, Caroline; Szatmari, Peter; Zwaigenbaum, Lonnie

    2016-01-01

    Considerable evidence on autism spectrum disorder emergence comes from longitudinal high-risk samples (i.e. younger siblings of children with autism spectrum disorder). Diagnostic stability to age 3 is very good when diagnosed as early as 18-24 months, but sensitivity is weaker, and relatively little is known beyond toddlerhood. We examined…

  19. School-aged functioning of children diagnosed with autism spectrum disorder before age three: parent-reported diagnostic, adaptive, medication, and school placement outcomes.

    PubMed

    Towle, Patricia O; Vacanti-Shova, Karyn; Shah, Shristi; Higgins-D'alessandro, Ann

    2014-06-01

    Eighty children with early autism spectrum disorder (ASD) diagnoses (under 36 months) were identified using a chart abstraction protocol applied to early intervention charts. Parents filled out questionnaires by mail when the children were school-aged (ages 6-16 years). Similar to previous studies, approximately 20% no longer had ASD diagnoses; the other participants were assigned to Moderate/Severe versus Mild ASD outcome groups. These three groups were compared across several variables, including diagnostic features and functional features including adaptive behavior, social experiences, medication use, and school placement. The findings expand our knowledge about outcomes in longitudinal studies of children with ASD, as well as provide support for using relatively indirect methods (chart review, parent questionnaire) to gather this type of information.

  20. Age and timing of the Permian mass extinctions: U/Pb dating of closed-system zircons.

    PubMed

    Mundil, Roland; Ludwig, Kenneth R; Metcalfe, Ian; Renne, Paul R

    2004-09-17

    The age and timing of the Permian-Triassic mass extinction have been difficult to determine because zircon populations from the type sections are typically affected by pervasive lead loss and contamination by indistinguishable older xenocrysts. Zircons from nine ash beds within the Shangsi and Meishan sections (China), pretreated by annealing followed by partial attack with hydrofluoric acid, result in suites of consistent and concordant uranium/lead (U/Pb) ages, eliminating the effects of lead loss. The U/Pb age of the main pulse of the extinction is 252.6 +/- 0.2 million years, synchronous with the Siberian flood volcanism, and it occurred within the quoted uncertainty.

  1. Interactions between hatch dates, growth rates, and mortality of Age-0 native Rainbow Smelt and nonnative Alewife in Lake Champlain

    USGS Publications Warehouse

    Parrish, Donna; Simonin, Paul W.; Rudstam, Lars G.; Pientka, Bernard; Sullivan, Patrick J.

    2016-01-01

    Timing of hatch in fish populations can be critical for first-year survival and, therefore, year-class strength and subsequent species interactions. We compared hatch timing, growth rates, and subsequent mortality of age-0 Rainbow Smelt Osmerus mordax and Alewife Alosa pseudoharengus, two common open-water fish species of northern North America. In our study site, Lake Champlain, Rainbow Smelt hatched (beginning May 26) almost a month earlier than Alewives (June 20). Abundance in the sampling area was highest in July for age-0 Rainbow Smelt and August for age-0 Alewives. Late-hatching individuals of both species grew faster than those hatching earlier (0.6 mm/d versus 0.4 for Rainbow Smelt; 0.7 mm/d versus 0.6 for Alewives). Mean mortality rate during the first 45 d of life was 3.4%/d for age-0 Rainbow Smelt and was 5.5%/d for age-0 Alewives. Alewife mortality rates did not differ with hatch timing but daily mortality rates of Rainbow Smelt were highest for early-hatching fish. Cannibalism is probably the primary mortality source for age-0 Rainbow Smelt in this lake. Therefore, hatching earlier may not be advantageous because the overlap of adult and age-0 Rainbow Smelt is highest earlier in the season. However, Alewives, first documented in Lake Champlain in 2003, may increase the mortality of age-0 Rainbow Smelt in the summer, which should favor selection for earlier hatching.

  2. An expansion of age constraints for microbial clades that lack a conventional fossil record using phylogenomic dating.

    PubMed

    Blank, Carrine E

    2011-10-01

    Most microbial taxa lack a conventional microfossil or biomarker record, and so we currently have little information regarding how old most microbial clades and their associated traits are. Building on the previously published oxygen age constraint, two new age constraints are proposed based on the ability of microbial clades to metabolize chitin and aromatic compounds derived from lignin. Using the archaeal domain of life as a test case, phylogenetic analyses, along with published metabolic and genetic data, showed that members of the Halobacteriales and Thermococcales are able to metabolize chitin. Ancestral state reconstruction combined with phylogenetic analysis of the genes underlying chitin degradation predicted that the ancestors of these two groups were also likely able to metabolize chitin or chitin-related compounds. These two clades were therefore assigned a maximum age of 1.0 Ga (when chitin likely first appeared). Similar analyses also predicted that the ancestor to the Sulfolobus solfataricus-Sulfolobus islandicus clade was able to metabolize phenol using catechol dioxygenase, so this clade was assigned a maximum age of 475 Ma. Inferred ages of archaeal clades using relaxed molecular clocks with the new age constraints were consistent with those inferred with the oxygen age constraints. This work expands our current toolkit to include Paleoproterozoic, Neoproterozoic, and Paleozoic age constraints, and should aid in our ability to phylogenetically reconstruct the antiquity of a wide array of microbial clades and their associated morphological and biogeochemical traits, spanning deep geologic time. Such hypotheses-although built upon evolutionary inferences-are fundamentally testable.

  3. Age of the Lava Creek supereruption and magma chamber assembly at Yellowstone based on 40Ar/39Ar and U-Pb dating of sanidine and zircon crystals

    NASA Astrophysics Data System (ADS)

    Vazquez, J. A.; Matthews, N. E.; Calvert, A. T.

    2015-12-01

    The last supereruption from the Yellowstone Plateau formed Yellowstone caldera and ejected the >1000 km3 of rhyolite that composes the Lava Creek Tuff (LCT). Tephra from the eruption blanketed much of the western United States, and is a key Quaternary chronostratigraphic marker, in particular for dating deposition of mid-Pleistocene glacial and pluvial deposits in western North America. We performed 40Ar/39Ar dating of single sanidines to delimit eruption age, and ion microprobe U-Pb and trace-element analyses of crystal faces on single zircons to characterize magmatic evolution and date near-eruption crystallization, as well as analyses of crystal interiors to date the interval of zircon crystallization. Sanidines from the two LCT members A and B yield an 40Ar/39Ar isochron date of 631 ± 4 ka (2σ). Crystal faces on zircons from both members yield a weighted mean 206Pb/238U date of 627 ± 6 ka (2σ) and have trace element concentrations that vary with eruptive stratigraphy. Zircon interiors yield a weighted mean 206Pb/238U date of 660 ± 6 ka, and reveal reverse and/or oscillatory zoning of trace element concentrations, with many crystals containing high-U concentrations and dark cathodoluminescence (CL) cores. These crystals with high-U cores are possibly sourced from 'defrosting' of melt-impregnated margins of the growing subvolcanic reservoir. LCT sanidines mirror the variation of zircon composition within the eruptive stratigraphy, with crystals from upper LCT-A and basal LCT-B having bright-CL rims with high Ba concentrations, suggesting late crystallization after addition of less evolved silicic magma. The occurrence of distal LCT in stratigraphic sequences marking the Marine Isotope Stage 16-15 transition supports the apparent eruption age of ca. 631 ka. These results reveal that Lava Creek zircons record episodic heating, renewed crystallization, and an overall up-temperature evolution for Yellowstone's subvolcanic reservoir in the 103-104 year interval

  4. Ultrasonic measurements of second and third trimester fetuses to predict gestational age and date of parturition in captive and wild spotted hyenas Crocuta crocuta.

    PubMed

    Place, Ned J; Weldele, Mary L; Wahaj, Sofia A

    2002-09-01

    Parturition in spotted hyenas (Crocuta crocuta) is a fascinating event to witness, as females of this species are highly masculinized and give birth through a penis-like clitoris. Furthermore, shortly after birth, a high rate of aggression occurs between littermates that can sometimes end in siblicide. To study these events thoroughly, an accurate estimate of the date of parturition is necessary. To this end, we performed transabdominal ultrasounds every 20-30 days in five captive spotted hyenas of known gestational age, beginning approximately 30 days after mating. We measured the femur length (FL), abdominal circumference (AC), and biparietal diameter (BPD) of eight fetuses from Days 42 to 100 of their 110 days of gestation. FL proved to be the most effective measurement, as it correlated well with gestational age and was easy to obtain consistently. The relationship between estimated gestational age (EGA) and FL is described by the equation: [EGA = 37.3 + (14.0 x FL)]. AC also correlated well with EGA, but was more difficult to measure than FL. Measuring BPD became increasingly difficult as pregnancies advanced beyond 70 days of gestation. Because gestational age is often not known in captive and free-ranging spotted hyenas, measuring fetal FL ultrasonographically is a rapid and reliable way to determine an approximate date of parturition. This technique proved invaluable when used to track and monitor a free-ranging spotted hyena during the days just before and after parturition.

  5. Sensory processing, school performance, and adaptive behavior of young school-age children with fetal alcohol spectrum disorders.

    PubMed

    Jirikowic, Tracy; Olson, Heather Carmichael; Kartin, Deborah

    2008-05-01

    This study described sensory processing behaviors and sensory-motor abilities in children with fetal alcohol spectrum disorders (FASD) and explored their relationship to home and school function. A clinic-referred sample of 25 children with FASD, ages 5 to 8 years, was compared with 26 children with typical development, balanced for age, gender, and race/ethnicity, on standardized tests examining sensory processing, sensory-motor performance, school performance, and adaptive behavior. Children with FASD scored significantly more poorly on sensory processing, sensory-motor, adaptive, and academic achievement measures, and demonstrated more problem behaviors at home and school. Correlations were significant between measures of sensory processing and sensory-motor performance, adaptive behavior, and some aspects of academic performance. Sensory processing and related foundational sensory-motor impairments should be considered when determining the developmental needs of children with FASD. These impairments may co-occur with and contribute, at least in part, to decreased adaptive and school function.

  6. Early Intervention for Children With Autism Spectrum Disorder Under 3 Years of Age: Recommendations for Practice and Research.

    PubMed

    Zwaigenbaum, Lonnie; Bauman, Margaret L; Choueiri, Roula; Kasari, Connie; Carter, Alice; Granpeesheh, Doreen; Mailloux, Zoe; Smith Roley, Susanne; Wagner, Sheldon; Fein, Deborah; Pierce, Karen; Buie, Timothy; Davis, Patricia A; Newschaffer, Craig; Robins, Diana; Wetherby, Amy; Stone, Wendy L; Yirmiya, Nurit; Estes, Annette; Hansen, Robin L; McPartland, James C; Natowicz, Marvin R

    2015-10-01

    This article reviews current evidence for autism spectrum disorder (ASD) interventions for children aged <3 years, based on peer-reviewed articles published up to December 2013. Several groups have adapted treatments initially designed for older, preschool-aged children with ASD, integrating best practice in behavioral teaching methods into a developmental framework based on current scientific understanding of how infants and toddlers learn. The central role of parents has been emphasized, and interventions are designed to incorporate learning opportunities into everyday activities, capitalize on "teachable moments," and facilitate the generalization of skills beyond the familiar home setting. Our review identified several comprehensive and targeted treatment models with evidence of clear benefits. Although some trials were limited to 8- to 12-week outcome data, enhanced outcomes associated with some interventions were evaluated over periods as long as 2 years. Based on this review, recommendations are proposed for clinical practice and future research.

  7. Eruption and magma crystallization ages of Las Tres Vírgenes (Baja California) constrained by combined 230Th/ 238U and (U-Th)/He dating of zircon

    NASA Astrophysics Data System (ADS)

    Schmitt, Axel K.; Stockli, Daniel F.; Hausback, Brian P.

    2006-11-01

    Las Tres Vírgenes volcano is a calc-alkaline composite cone located near the main Gulf of California escarpment on the E coast of the Baja California peninsula. High-sensitivity ion microprobe U-series ( 230Th/ 238U) ages for zircon from La Vírgen tephra average 121 - 10 + 12 ka (1σ; MSWD = 2.7), with discrete age peaks at ˜ 100 and 160 ka. The noble gas mass spectrometric (U-Th)/He zircon age, corrected for disequilibrium and pre-eruptive storage, is 36 ± 3 ka. This result for the eruption age of La Vírgen tephra is significantly older than previously postulated historic or Holocene ages that were based on an 18th century map reference and 14C dating of accidental charcoal, respectively. The new (U-Th)/He zircon age is consistent with a > 26 ± 4 ka age derived from cosmogenic He exposure dating of an overlying basaltic lava flow [Hausback, B.P. and Abrams, M.J., 1996. Plinian eruption of La Virgen Tephra, Volcán Las Tres Virgenes, Baja California Sur, Mexico. Eos, Transactions, American Geophysical Union, 77(46, Suppl.): 813-814.]. U-Pb zircon analysis of ignimbrites erupted from the adjacent Early Pleistocene La Reforma and El Aguajito calderas yielded ages of 1.38 ± 0.03 Ma ( n = 12; MSWD = 1.0) and 1.17 ± 0.07 Ma ( n = 23; MSWD = 1.3), respectively. No evidence for these ages is found among La Vírgen zircons, whereas pre-Quaternary zircon xenocrysts are common. The La Vírgen magma, therefore, evolved unrelated to Early Pleistocene magmatism in adjacent calderas, but assimilated local basement rocks. A gap between average Th-U and (U-Th)/He zircon ages suggests that zircon crystallization was discontinuous in the La Vírgen magma chamber. In addition, partial resorption of zircon suggests episodic thermal rejuvenation, most likely by basaltic recharge. Based on the zircon record, the > 100 ka lifetime of the thermal anomaly that sustained repeated intrusive pulses significantly exceeds the age of the last eruption. This strengthens the view that Tres

  8. Age-related differences in restricted repetitive behaviors in autism spectrum disorders.

    PubMed

    Esbensen, Anna J; Seltzer, Marsha Mailick; Lam, Kristen S L; Bodfish, James W

    2009-01-01

    Restricted repetitive behaviors (RRBs) were examined in a large group of children, adolescents and adults with ASD in order to describe age-related patterns of symptom change and association with specific contextual factors, and to examine if the patterns of change are different for the various types of RRBs. Over 700 individuals with ASD were rated on the Repetitive Behavior Scale-Revised. RRBs were less frequent and less severe among older than younger individuals, corroborating that autism symptoms abate with age. Our findings further suggest that repetitive behaviors are a heterogeneous group of behaviors, with the subtypes of RRBs having their own individual patterns across the lifespan, and in some cases, a differential association with age depending on intellectual functioning.

  9. High precision dating of mass extinction events: a combined zircon geochronology, apatite tephrochronology, and Bayesian age modelling approach of the Permian-Triassic boundary extinction

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    Chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb dating of single-zircon crystals is preferably applied to tephra beds intercalated in sedimentary sequences. By assuming that the zircon crystallization age closely approximate that of the volcanic eruption and ash deposition, U-Pb zircon geochronology is the preferred approach for dating mass extinction events (such as the Permian-Triassic boundary mass extinction) in the sedimentary record. As tephra from large volcanic eruptions is often transported over long distances, it additionally provide an invaluable tool for stratigraphic correlation across distant geologic sections. Therefore, the combination of high-precision zircon geochronology with apatite chemistry of the same tephra bed (so called apatite tephrochronology) provides a robust fingerprint of one particular volcanic eruption. In addition we provide coherent Bayesian model ages for the Permian-Triassic boundary (PTB) mass extinction, then compare it with PTB model ages at Meishan after Burgess et al. (2014). We will present new high-precision U-Pb zircon dates for a series of volcanic ash beds in deep- and shallow-marine Permian-Triassic sections in the Nanpanjiang Basin, South China. In addition, apatite crystals out of the same ash beds were analysed focusing on their halogen (F, Cl) and trace-element (e.g. Fe, Mg, REE) chemistry. We also show that Bayesian age models produce reproducible results from different geologic sections. On the basis of these data, including litho- and biostratigraphic correlations, we can precisely and accurately constrain the Permian-Triassic boundary in an equatorial marine setting, and correlate tephra beds over different sections and facies in the Nanpanjiang Basin independently from litho-, bio- or chemostratigraphic criteria. The results evidence that data produced in laboratories associated to the global EARTHTIME consortium can provide age information at the 0.05% level of 206

  10. Age-Related Differences in Restricted Repetitive Behaviors in Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Esbensen, Anna J.; Seltzer, Marsha Mailick; Lam, Kristen S. L.; Bodfish, James W.

    2009-01-01

    Restricted repetitive behaviors (RRBs) were examined in a large group of children, adolescents and adults with ASD in order to describe age-related patterns of symptom change and association with specific contextual factors, and to examine if the patterns of change are different for the various types of RRBs. Over 700 individuals with ASD were…

  11. Neurocognition across the spectrum of mucopolysaccharidosis type I: Age, severity, and treatment

    PubMed Central

    Shapiro, Elsa G.; Nestrasil, Igor; Rudser, Kyle; Delaney, Kathleen; Kovac, Victor; Ahmed, Alia; Yund, Brianna; Orchard, Paul J.; Eisengart, Julie; Niklason, Gregory R.; Raiman, Julian; Mamak, Eva; Cowan, Morton J.; Bailey-Olson, Mara; Harmatz, Paul; Shankar, Suma P.; Cagle, Stephanie; Ali, Nadia; Steiner, Robert D.; Wozniak, Jeffrey; Lim, Kelvin O.; Whitley, Chester B.

    2015-01-01

    Objectives Precise characterization of cognitive outcomes and factors that contribute to cognitive variability will enable better understanding of disease progression and treatment effects in mucopolysaccharidosis type I (MPS I). We examined the effects on cognition of phenotype, genotype, age at evaluation and first treatment, and somatic disease burden. Methods Sixty patients with severe MPS IH (Hurler syndrome treated with hematopoietic cell transplant and 29 with attenuated MPS I treated with enzyme replacement therapy), were studied with IQ measures, medical history, genotypes. Sixty-seven patients had volumetric MRI. Subjects were grouped by age and phenotype and MRI and compared to 96 normal controls. Results Prior to hematopoietic cell transplant, MPS IH patients were all cognitively average, but post-transplant, 59% were below average, but stable. Genotype and age at HCT were associated with cognitive ability. In attenuated MPS I, 40% were below average with genotype and somatic disease burden predicting their cognitive ability. White matter volumes were associated with IQ for controls, but not for MPS I. Gray matter volumes were positively associated with IQ in controls and attenuated MPS I patients, but negatively associated in MPS IH. Conclusions Cognitive impairment, a major difficulty for many MPS I patients, is associated with genotype, age at treatment and somatic disease burden. IQ association with white matter differed from controls. Many attenuated MPS patients have significant physical and/or cognitive problems and receive insufficient support services. Results provide direction for future clinical trials and better disease management. PMID:26095521

  12. Magnetic resonance imaging and neuropsychological testing in the spectrum of normal aging

    PubMed Central

    Foss, Maria Paula; Diniz, Paula Rejane Beserra; Formigheri, Paulo; Salmon, Carlos Ernesto Garrido; Speciali, José Geraldo; Santos, Antônio Carlos

    2013-01-01

    OBJECTIVE: To understand the relationships between brain structures and function (behavior and cognition) in healthy aging. METHOD: The study group was composed of 56 healthy elderly subjects who underwent neuropsychological assessment and quantitative magnetic resonance imaging. Cluster analysis classified the cohort into two groups, one (cluster 1) in which the magnetic resonance imaging metrics were more preserved (mean age: 66.4 years) and another (cluster 2) with less preserved markers of healthy brain tissue (mean age: 75.4 years). RESULTS: The subjects in cluster 2 (older group) had worse indices of interference in the Stroop test compared with the subjects in cluster 1 (younger group). Therefore, a simple test such as the Stroop test could differentiate groups of younger and older subjects based on magnetic resonance imaging metrics. CONCLUSION: These results are in agreement with the inhibitory control hypotheses regarding cognitive aging and may also be important in the interpretation of studies with other clinical groups, such as patients with dementia and mild cognitive impairment. PMID:24141834

  13. Luminescence- and Infrared-Radiofluorescence dating of the Acheulean- to Middle Stone Age sedimentary sequence at Montagu Cave, Western Cape Provence, South Africa

    NASA Astrophysics Data System (ADS)

    Lauer, Tobias; Archer, Will; Sumner, Alexandra

    2016-04-01

    Montagu Cave is an archaeological site located on the edge of the Langeberg mountain range, about 160 km NE of Cape Town, in South Africa. The archaeological and sedimentary units at Montagu Cave comprise two Acheulean sequences which are separated from one another by a substantial archaeological hiatus. There is an additional Middle Stone Age sequence which overlies the Acheulean horizons, and contains layers attributed to the Howiesons Poort, as well as multiple other Middle Stone Age sub-stages. Hence, Montagu Cave provides a unique opportunity to investigate quite complex population level questions concerning the behavioral differences between modern and pre-modern populations in southern Africa. However, thus far, the chronological context of the sediment-layers at the site remains unclear. It is therefore critical to provide a resilient chronological framework for the timing of human activity at the site. This study concerns the potential of luminescence dating for the sedimentary sequence preserved at Montagu cave. The collected samples are tested on their quartz- and feldspar luminescence signal properties. Various optical dating techniques (quartz OSL; pIRIR290) will be applied, and the results of each compared in order to obtain information on the suitability of the material for luminescence dating, and to establish a chronological framework for this important archaeological site. Furthermore, the infrared-radiofluorescence (IR-RF) signal behavior will be tested on potassium feldspars, as IR-RF is a method being able to date back up to > 600 ka. IR-RF therefore has the potential to cover the expected time-frame of the sediments at Montagu-cave.

  14. Executive function deficits in autism spectrum disorders and attention-deficit/hyperactivity disorder: examining profiles across domains and ages.

    PubMed

    Happé, Francesca; Booth, Rhonda; Charlton, Rebecca; Hughes, Claire

    2006-06-01

    Deficits in 'executive function' (EF) are characteristic of several clinical disorders, most notably Autism Spectrum Disorders (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD). In this study, age- and IQ-matched groups with ASD, ADHD, or typical development (TD) were compared on a battery of EF tasks tapping three core domains: response selection/inhibition, flexibility, and planning/working memory. Relations between EF, age and everyday difficulties (rated by parents and teachers) were also examined. Both clinical groups showed significant EF impairments compared with TD peers. The ADHD group showed greater inhibitory problems on a Go-no-Go task, while the ASD group was significantly worse on response selection/monitoring in a cognitive estimates task. Age-related improvements were clearer in ASD and TD than in ADHD. At older (but not younger) ages, the ASD group outperformed the ADHD group, performing as well as the TD group on many EF measures. EF scores were related to specific aspects of communicative and social adaptation, and negatively correlated with hyperactivity in ASD and TD. Within the present groups, the overall findings suggested less severe and persistent EF deficits in ASD (including Asperger Syndrome) than in ADHD.

  15. Discrepancies between academic achievement and intellectual ability in higher-functioning school-aged children with autism spectrum disorder.

    PubMed

    Estes, Annette; Rivera, Vanessa; Bryan, Matthew; Cali, Philip; Dawson, Geraldine

    2011-08-01

    Academic achievement patterns and their relationships with intellectual ability, social abilities, and problem behavior are described in a sample of 30 higher-functioning, 9-year-old children with autism spectrum disorder (ASD). Both social abilities and problem behavior have been found to be predictive of academic achievement in typically developing children but this has not been well studied in children with ASD. Participants were tested for academic achievement and intellectual ability at age 9. Problem behaviors were assessed through parent report and social functioning through teacher report at age 6 and 9. Significant discrepancies between children's actual academic achievement and their expected achievement based on their intellectual ability were found in 27 of 30 (90%) children. Both lower than expected and higher than expected achievement was observed. Children with improved social skills at age 6 demonstrated higher levels of academic achievement, specifically word reading, at age 9. No relationship was found between children's level of problem behavior and level of academic achievement. These results suggest that the large majority of higher-functioning children with ASD show discrepancies between actual achievement levels and levels predicted by their intellectual ability. In some cases, children are achieving higher than expected, whereas in others, they are achieving lower than expected. Improved social abilities may contribute to academic achievement. Future studies should further explore factors that can promote strong academic achievement, including studies that examine whether intervention to improve social functioning can support academic achievement in children with ASD.

  16. Semantic Verbal Fluency in Children with and without Autism Spectrum Disorder: Relationship with Chronological Age and IQ

    PubMed Central

    Pastor-Cerezuela, Gemma; Fernández-Andrés, Maria-Inmaculada; Feo-Álvarez, Mireia; González-Sala, Francisco

    2016-01-01

    We administered a semantic verbal fluency (SVF) task to two groups of children (age range from 5 to 8): 47 diagnosed with Autism Spectrum Disorder (ASD Group) and 53 with typical development (Comparison Group), matched on gender, chronological age, and non-verbal IQ. Four specific indexes were calculated from the SVF task, reflecting the different underlying cognitive strategies used: clustering (component of generativity and lexical-semantic access), and switching (executive component, cognitive flexibility). First, we compared the performance of the two groups on the different SVF task indicators, with the ASD group scoring lower than the Comparison Group, although the difference was greater on switching than on clustering. Second, we analyzed the relationships between the different SVF measures and chronological age, verbal IQ and non-verbal IQ. While in the Comparison Group chronological age was the main predictor of performance on the SVF task, in the ASD Group verbal IQ was the best predictor. In the children with ASD, therefore, greater linguistic competence would be associated with better performance on the SVF task, which should be taken into account in speech therapies designed to achieve improvements in linguistic generativity and cognitive flexibility. PMID:27379002

  17. Muscleblind-like 3 deficit results in a spectrum of age-associated pathologies observed in myotonic dystrophy

    PubMed Central

    Choi, Jongkyu; Dixon, Donald M.; Dansithong, Warunee; Abdallah, Walid F.; Roos, Kenneth P.; Jordan, Maria C.; Trac, Brandon; Lee, Han Shin; Comai, Lucio; Reddy, Sita

    2016-01-01

    Myotonic dystrophy type I (DM1) exhibits distinctive disease specific phenotypes and the accelerated onset of a spectrum of age-associated pathologies. In DM1, dominant effects of expanded CUG repeats result in part from the inactivation of the muscleblind-like (MBNL) proteins. To test the role of MBNL3, we deleted Mbnl3 exon 2 (Mbnl3ΔE2) in mice and examined the onset of age-associated diseases over 4 to 13 months of age. Accelerated onset of glucose intolerance with elevated insulin levels, cardiac systole deficits, left ventricle hypertrophy, a predictor of a later onset of heart failure and the development of subcapsular and cortical cataracts is observed in Mbnl3ΔE2 mice. Retention of embryonic splice isoforms in adult organs, a prominent defect in DM1, is not observed in multiple RNAs including the Insulin Receptor (Insr), Cardiac Troponin T (Tnnt2), Lim Domain Binding 3 (Ldb3) RNAs in Mbnl3ΔE2 mice. Although rare DM1-like splice errors underlying the observed phenotypes cannot be excluded, our data in conjunction with the reported absence of alternative splice errors in embryonic muscles of a similar Mbnl3ΔE2 mouse by RNA-seq studies, suggest that mechanisms distinct from the adult retention of embryonic splice patterns may make important contributions to the onset of age-associated pathologies in DM1. PMID:27484195

  18. The effect of body condition, live weight, breed, age, calf performance, and calving date on reproductive performance of spring-calving beef cows.

    PubMed

    Osoro, K; Wright, I A

    1992-06-01

    Data from 321 spring-calving cows (mean calving date March 27) were used to assess the effects of body condition, live weight, cow age (from 4 to 13 yr), and breed (237 Hereford x Friesians and 84 Blue-Greys) and time of calving on the proportion of cows that became pregnant, the number of days from the start of mating to pregnancy, and calving interval. Mating started at turn-out to pasture in mid-May and lasted 9 to 10 wk. Body condition at calving and breed were the most significant animal factors affecting reproductive performance. Cows calving in higher body condition had shorter (P less than .001) calving intervals (11.2 d per unit of body condition at calving). Blue-Grey cows became pregnant in a higher proportion (90%) and calving interval was shorter (364 d) than in Hereford x Friesians (83%; 374 d). Body condition at the start of mating was less important and body condition at the end of mating had no effect. Live weight at calving and changes in live weight from calving to the start of mating and during the mating period had no significant effect. The proportion of cows becoming pregnant decreased significantly with age in Hereford x Friesian cows older than 7 yr. The variance in calving interval accounted for by calving date, body condition at calving, breed, and age was 42%.

  19. Stability and change in autism spectrum disorder diagnosis from age 3 to middle childhood in a high-risk sibling cohort.

    PubMed

    Brian, Jessica; Bryson, Susan E; Smith, Isabel M; Roberts, Wendy; Roncadin, Caroline; Szatmari, Peter; Zwaigenbaum, Lonnie

    2016-10-01

    Considerable evidence on autism spectrum disorder emergence comes from longitudinal high-risk samples (i.e. younger siblings of children with autism spectrum disorder). Diagnostic stability to age 3 is very good when diagnosed as early as 18-24 months, but sensitivity is weaker, and relatively little is known beyond toddlerhood. We examined stability and change in blinded, clinical best-estimate diagnosis from age 3 to middle childhood (mean age = 9.5 years) in 67 high-risk siblings enrolled in infancy. Good agreement emerged for clinical best-estimate diagnoses (89.6% overall; kappa = 0.76, p < 0.001, 95% confidence interval = 0.59-0.93). At age 3, 18 cases (26.9%) were classified with "autism spectrum disorder": 17 retained their autism spectrum disorder diagnosis (94.4%; 13 boys, 4 girls) and 1 no longer met autism spectrum disorder criteria at follow-up. Among "non-autism spectrum disorder" cases at age 3, 43/49 remained non-autism spectrum disorder at follow-up (87.8%; 22 boys, 21 girls) and 6/49 met lower autism symptomatology criteria ("Later-Diagnosed"; 3 boys, 3 girls). Later-diagnosed cases had significantly lower autism spectrum disorder symptomatology and higher receptive language at age 3 and trends toward lower autism symptoms and higher cognitive abilities at follow-up. Emerging developmental concerns were noted in all later-diagnosed cases, by age 3 or 5. High-risk children need to be followed up into middle childhood, particularly when showing differences in autism-related domains.

  20. On the age of the Onverwacht Group, Swaziland sequence, South Africa. [radioactive dating of stratified igneous rocks

    NASA Technical Reports Server (NTRS)

    Jahn, B.-M.; Shih, C.-Y.

    1974-01-01

    Some rocks of the Onverwacht Group, South Africa, have been analyzed for Rb and Sr concentrations and Sr isotopic composition. These rocks include volcanic rocks, layered ultramafic differentiates and cherty sediments. Whole rock data indicate that the Rb-Sr isotopic systems in many samples were open and yield no reasonable isochron relationships. However, the data of mineral separates from a basaltic komatiite define a good isochron of 3.50 (plus or minus .2) b.y. with an initial Sr-87/Sr-86 ratio of 0.70048 plus or minus 5. The orthodox interpretation of this age is the time of the low grade metamorphism. It is reasonable to assume that the age of 3.50 b.y. might also represent the time of initial Onverwacht volcanism and deposition. The initial Sr-87/Sr-86 ratio obtained above is important to an understanding of the Sr isotopic composition of the Archean upper mantle.

  1. Dating Melt Rock 63545 By Rb-Sr and Sm-Nd: Age of Imbrium; Spa Dress Rehearsal

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Shih, C. Y.; Reese, Y. D.

    2011-01-01

    Apollo 16 sample 63545 was initially described as one of a group of 19 generally rounded, fine-grained, crystalline rocks that were collected as rake samples [1]. This 16 g "rocklet" was collected at Station 13 on the ejecta blanket of North Ray Crater at the foot of Smoky Mountain [2]. Originally classified as a Very High Alumina (VHA) basalt on geochemical grounds [3], it was later argued to be an impact melt rock [4]. Here we report a Rb-Sr and Sm-Nd isotopic study that shows that some portions of the rock failed to reach isotopic equilibrium on last melting in agreement with the impact melt rock interpretation. Nevertheless, by omitting mineral fractions that are discordant with the majority of the data, we arrive at the time of last melting as 3.88 plus or minus 0.05 Ga ago. This age is in agreement with the Ar-39/Ar-40 plateau age of 3839 plus or minus 23 Ma [5], if the latter is adjusted for the 1.4-1.8% revision in the age of the hornblende monitor [6]. This investigation was undertaken in part as proof-of-concept for SPA-basin sample return.

  2. Criminal history and assault of dating partners: the role of type of prior crime, age of onset, and gender.

    PubMed

    Straus, Murray A; Ramirez, I Luis

    2004-08-01

    Some studies of assaults on intimate partners have found that most of the perpetrators are not violent outside the family, which suggests a specialized type of crime. However, other studies found domestic violence offenders tend to have extensive criminal histories. To further investigate the extent to which partner assaults are part of a more general pattern of criminal behavior or a specialized type of crime, we studied the dating relationships of 653 university students. Thirty-one percent reported assaulting a partner in the previous 12 months. The rate of assault on partners by females did not differ significantly for males (29%) and females (32%). We also found high rates of other self-reported crime, and much higher rates by males. For example, over one half of the male students and almost one third of the female students reported having stolen money. The male students reported an average of 3.4 crimes committed, and the female students an average of 1.4 crimes. These high crime rates and gender differences are consistent with many previous studies. Logistic regression analysis revealed that a history of prior criminal acts is associated with an increased probability of assaulting a partner. The relationship was greater when there was prior violent crime compared to property crime, when there was early onset of criminal behavior, and when the offender was female. The implications of the findings for understanding partner assaults, criminal careers, and gender differences in the etiology of violence against intimate partners are discussed.

  3. An alternative hypothesis for high-T 40Ar/39Ar age spectrum discordance in polyphase extraterrestrial materials

    NASA Astrophysics Data System (ADS)

    Cassata, W. S.; Shuster, D. L.; Renne, P. R.; Weiss, B. P.

    2009-12-01

    relationships intersect). Thus, very brief, high-temperature shock-heating events may preferentially degas pyroxene without significantly resetting glass and plagioclase 40Ar/39Ar age spectra. This effect would be enhanced by highly localized shock-heating focused along pyroxene (sub)grain boundaries, as has been inferred in other cases (e.g., 3). The shock and impact origin of this feature may explain its frequent appearance in ET samples, regardless of grain size, as well as the general absence of terrestrial analogs. We will present new 40Ar/39Ar data from Martian meteorites and physical models to distinguish between these competing hypotheses. References Cited: 1. Turner & Cadogan, 1974, Possible effects of 39Ar recoil in 40Ar-39Ar dating. Proc. 5th LPSC, 1601- 1615. 2. Huneke & Smith, 1976, The realities of recoil: 39Ar recoil out of small grains and anomalous age patterns in 40Ar-39Ar dating. Proc. 7th LPSC, 1987-2008. 3. Min et al., 2003, Single grain (U-Th)/He ages from phosphates in Acapulco meteorite and implications for thermal history. EPSL 209, 323-336.

  4. Investigation of Small-Scale Age Inversions in Stalagmites Using in Situ 230Th/U-Dating By Laser Ablation-MC-ICP-MS

    NASA Astrophysics Data System (ADS)

    Jochum, K. P.; Lin, Y.; Scholz, D.; Weis, U.; Stoll, B.; Andreae, M. O.

    2014-12-01

    Post-depositional U loss or addition in stalagmites lead to increasing/decreasing (230Th/238U) activity ratios and thus to older/younger 230Th/U-ages, respectively. In order to determine potential small-scale age inversions, we determined 230Th, 234U, and 238U isotope abundances in a stalagmite from the Hüttenbläserschachthöhle, western Germany, applying a high-spatial-resolution in-situ LA-MC-ICP-MS technique. This sample has the advantage that - because of its aragonitic composition - the U content is high (several µg g-1) and that large-scale age inversions have been previously detected by solution MC-ICP-MS. Due to the low intensity of 230Th (20 - 80 cps), we carefully optimized the operating parameters of the 213 nm Nd:YAG laser, such as scan speed (4 µm s-1), ablation time (1000 s), spot size (110 µm), and pulse repetition rate (20 Hz). We obtained a repeatability (RSE) of about 0.6 % - 0.9 % for 230Th/238U. The isotope ratios were corrected for instrumental biases using an external carbonate reference material (i.e., a flowstone in secular equilibrium). Including all sources of analytical uncertainty, we obtain a total age error (2 SE) of ca. 8 ka for a 215 ka old sample. Repeated dating of the same layers of the stalagmite yields a reproducibility of ca. 4 %. The LA-MC-ICPMS ages agree with the solution MC-ICP-MS ages within the analytical uncertainty. The high spatial resolution enables to detect small, but significant age inversions, which could not be detected by solution MC-ICP-MS. These inversions can be explained by diagenesis of speleothem CaCO3, which may play an important role for the alteration of speleothem ages.

  5. New 40Ar/ 39Ar dating results from the Shanwang Basin, eastern China: Constraints on the age of the Shanwang Formation and associated biota

    NASA Astrophysics Data System (ADS)

    He, Huaiyu; Deng, Chenglong; Pan, Yongxin; Deng, Tao; Luo, Zhaohua; Sun, Jimin; Zhu, Rixiang

    2011-07-01

    The fluvio-lacustrine sequence of the Shanwang Basin, eastern China, preserves a rich and important terrestrial fossil fauna and flora; the exceptional preservation of these fossils reveals the dynamics of ancient mammalian ecosystems and plant biology. However, the timing of this sedimentary sequence has been the subject of debate for decades. Here we contribute to this debate by presenting the detailed results of 40Ar/ 39Ar analysis of the basalts above, below, and within the Shanwang Formation. These dates place stringent constraints on the age of Shanwang Formation and associated biota. 40Ar/ 39Ar ages obtained from basalts of the Niushan and Yaoshan Formations, which underlie and overlie the Shanwang Formation, are 21.0 ± 2.5 Ma (2σ, full external error) and 17.3 ± 1.5 Ma (2σ, full external error), respectively. The 40Ar/ 39Ar age of the basalt in the Shanwang Formation is 17-18 Ma. Given the age constraints of the basalts of the Yaoshan and Shanwang Formations, the age of the Shanwang biota is estimated to be ca. 17 Ma, late Burdigalian of the Early Miocene, indicating that the deposition of this fauna coincided with the onset of the mid-Miocene Climatic Optimum. The results provide new age constraints on the Shanwang mammal fauna, and independently support interpretations that this fauna can be assigned to chronozone MN4, and correlated with middle Orleanian of the European Land Mammal Age, and to late Hemingfordian of the North American Land Mammal Age. Biological diversity of the Shanwang Formation could reflect the global-scale mid-Miocene Climatic Optimum.

  6. Refined depositional history and dating of the Tongaporutuan reference section, north Taranaki, New Zealand: new volcanic ash U-Pb zircon ages, biostratigraphy and sedimentation rates

    USGS Publications Warehouse

    Maier, K.L.; Crundwell, Martin P.; Coble, Matthew A.; Kingsley-Smith, Peter R.; Graham, Stephan A.

    2016-01-01

    This study presents new radiometric ages from volcanic ash beds within a c. 1900 m thick, progradational, deep-water clastic slope succession of late Miocene age exposed along the north Taranaki coast of the North Island, New Zealand. The ash beds yield U–Pb zircon ages ranging from 10.63 ± 0.65 Ma to 8.97 ± 0.22 Ma. The new ages are compatible with and provide corroboration of New Zealand Tongaporutuan Stage planktic foraminiferal and bolboformid biostratigraphic events identified in the same section. The close accord between these two age datasets provides a stratigraphically consistent and coherent basis for examining margin evolution. The arrival of a prograding clastic wedge and ensuing upward shoaling is recorded by sedimentation rates c. 2000 m/Ma–1 that are an order of magnitude higher than sedimentation rates on the precursor deep basin floor. This outcrop study provides new constraints for interpreting analogous subsurface deposits in Taranaki Basin and complements the regional late Miocene biostratigraphic dating framework.

  7. Divergence of Age-Related Differences in Social-Communication: Improvements for Typically Developing Youth but Declines for Youth with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Wallace, Gregory L.; Dudley, Katerina; Anthony, Laura; Pugliese, Cara E.; Orionzi, Bako; Clasen, Liv; Lee, Nancy Raitano; Giedd, Jay N.; Martin, Alex; Raznahan, Armin; Kenworthy, Lauren

    2017-01-01

    Although social-communication difficulties and repetitive behaviors are hallmark features of autism spectrum disorder (ASD) and persist across the lifespan, very few studies have compared age-related differences in these behaviors between youth with ASD and same-age typically developing (TD) peers. We examined this issue using SRS-2 (Social…

  8. Predictors of Age of Diagnosis for Children with Autism Spectrum Disorder: The Role of a Consistent Source of Medical Care, Race, and Condition Severity

    ERIC Educational Resources Information Center

    Emerson, Natacha D.; Morrell, Holly E. R.; Neece, Cameron

    2016-01-01

    Having a consistent source of medical care may facilitate diagnosis of autism spectrum disorders (ASD). This study examined predictors of age of ASD diagnosis using data from the 2011-2012 National Survey of Children's Health. Using multiple linear regression analysis, age of diagnosis was predicted by race, ASD severity, having a consistent…

  9. The Fears, Phobias and Anxieties of Children with Autism Spectrum Disorders and Down Syndrome: Comparisons with Developmentally and Chronologically Age Matched Children

    ERIC Educational Resources Information Center

    Evans, David W.; Canavera, Kristin; Kleinpeter, F. Lee; Maccubbin, Elise; Taga, Ken

    2005-01-01

    This study compared the fears and behavior problems of 25 children with an autism spectrum disorder (ASD), 43 children with Down syndrome (DS), 45 mental age (MA) matched children, and 37 chronologically age (CA) matched children. Children's fears, phobias, anxieties and behavioral problems were assessed using parent reports. Significant…

  10. Parental Age and Assisted Reproductive Technology in Autism Spectrum Disorders, Attention Deficit Hyperactivity Disorder, and Tourette Syndrome in a Japanese Population

    ERIC Educational Resources Information Center

    Shimada, Takafumi; Kitamoto, Atsushi; Todokoro, Ayako; Ishii-Takahashi, Ayaka; Kuwabara, Hitoshi; Kim, Soo-Yung; Watanabe, Kei-ichiro; Minowa, Iwao; Someya, Toshikazu; Ohtsu, Hiroshi; Osuga, Yutaka; Kano, Yukiko; Kasai, Kiyoto; Kato, Nobumasa; Sasaki, Tsukasa

    2012-01-01

    We investigated whether advanced parental age and assisted reproductive technology (ART) are risk factors in autism spectrum disorders (ASDs), attention deficit hyperactivity disorder (ADHD), and Tourette syndrome (TS). Clinical charts of Japanese outpatients with ASD (n = 552), ADHD (n = 87), and TS (n = 123) were reviewed. Parental age of…

  11. Origins of the Iberomaurusian in NW Africa: new AMS radiocarbon dating of the Middle and Later Stone Age deposits at Taforalt Cave, Morocco.

    PubMed

    Barton, R N E; Bouzouggar, A; Hogue, J T; Lee, S; Collcutt, S N; Ditchfield, P

    2013-09-01

    Recent genetic studies based on the distribution of mtDNA of haplogroup U6 have led to subtly different theories regarding the arrival of modern human populations in North Africa. One proposes that groups of the proto-U6 lineage spread from the Near East to North Africa around 40-45 ka (thousands of years ago), followed by some degree of regional continuity. Another envisages a westward human migration from the Near East, followed by further demographic expansion at ∼22 ka centred on the Maghreb and associated with a microlithic bladelet culture known as the Iberomaurusian. In evaluating these theories, we report on the results of new work on the Middle (MSA) and Later Stone (LSA) Age deposits at Taforalt Cave in Morocco. We present 54 AMS radiocarbon dates on bone and charcoals from a sequence of late MSA and LSA occupation levels of the cave. Using Bayesian modelling we show that an MSA non-Levallois flake industry was present until ∼24.5 ka Cal BP (calibrated years before present), followed by a gap in occupation and the subsequent appearance of an LSA Iberomaurusian industry from at least 21,160 Cal BP. The new dating offers fresh light on theories of continuity versus replacement of populations as presented by the genetic evidence. We examine the implications of these data for interpreting the first appearance of the LSA in the Maghreb and providing comparisons with other dated early blade and bladelet industries in North Africa.

  12. Gender ratio in a clinical population sample, age of diagnosis and duration of assessment in children and adults with autism spectrum disorder.

    PubMed

    Rutherford, Marion; McKenzie, Karen; Johnson, Tess; Catchpole, Ciara; O'Hare, Anne; McClure, Iain; Forsyth, Kirsty; McCartney, Deborah; Murray, Aja

    2016-07-01

    This article reports on gender ratio, age of diagnosis and the duration of assessment procedures in autism spectrum disorder diagnosis in a national study which included all types of clinical services for children and adults. Findings are reported from a retrospective case note analysis undertaken with a representative sample of 150 Scottish children and adults recently diagnosed with autism spectrum disorder. The study reports key findings that the gender ratio in this consecutively referred cohort is lower than anticipated in some age groups and reduces with increasing age. The gender ratio in children, together with the significant difference in the mean age of referral and diagnosis for girls compared to boys, adds evidence of delayed recognition of autism spectrum disorder in younger girls. There was no significant difference in duration of assessment for males and females suggesting that delays in diagnosis of females occur prior to referral for assessment. Implications for practice and research are considered.

  13. Developing 226Ra and 227Ac age-dating techniques for nuclear forensics to gain insight from concordant and non-concordant radiochronometers

    DOE PAGES

    Kayzar, Theresa M.; Williams, Ross W.

    2015-09-26

    The model age or ‘date of purification’ of a nuclear material is an important nuclear forensic signature. In this study, chemical separation and MC-ICP-MS measurement techniques were developed for 226 Ra and 227Ac: grand-daughter nuclides in the 238U and 235U decay chains respectively. The 230Th-234U, 226Ra-238U, 231Pa-235U, and 227Ac-235U radiochronometers were used to calculate model ages for CRM-U100 standard reference material and two highly-enriched pieces of uranium metal from the International Technical Working Group Round Robin 3 Exercise. In conclusion, the results demonstrate the accuracy of the 226Ra-238U and 227Ac-235U chronometers and provide information about nuclide migration during uranium processing.

  14. The relationship of motor skills and social communicative skills in school-aged children with autism spectrum disorder.

    PubMed

    MacDonald, Megan; Lord, Catherine; Ulrich, Dale A

    2013-07-01

    Motor skill deficits are present and persist in school-aged children with autism spectrum disorder (ASD; Staples & Reid, 2010). Yet the focus of intervention is on core impairments, which are part of the diagnostic criteria for ASD, deficits in social communication skills. The purpose of this study is to determine whether the functional motor skills, of 6- to 15-year-old children with high-functioning ASD, predict success in standardized social communicative skills. It is hypothesized that children with better motor skills will have better social communicative skills. A total of 35 children with ASD between the ages of 6-15 years participated in this study. The univariate GLM (general linear model) tested the relationship of motor skills on social communicative skills holding constant age, IQ, ethnicity, gender, and clinical ASD diagnosis. Object-control motor skills significantly predicted calibrated ASD severity (p < .05). Children with weaker motor skills have greater social communicative skill deficits. How this relationship exists behaviorally, needs to be explored further.

  15. The effects of acid leaching on 40Ar/39Ar age dating results using samples from the Walvis Ridge hotspot trail

    NASA Astrophysics Data System (ADS)

    Klath, J. F.; Koppers, A. A.; Heaton, D. E.; Schnur, S.

    2013-12-01

    In this study we systematically explore how acid leaching can be used to reduce the negative effects of seawater alteration on the 40Ar/39Ar age dating of submarine basalts. Koppers et al (2000) showed that acid leaching of groundmass samples generated more consistent ages as well as ages more concordant with phenocrystic mineral phases, compared to samples that were left untreated. By studying the effects of progressively increasing the strength and length of acid treatment, we will show how acid leaching of groundmass separates reduces alteration while leaving the initial eruption signature intact. Samples were chosen from the Walvis ridge hotspot trail in the southeast Atlantic. Three samples were selected based on degree and style of alteration. Two samples (basalt and basaltic andesite) appear highly altered in thin section. The basalt contains diffuse iddingsite alteration that is pervasive throughout the groundmass. The basaltic andesite displays focused secondary mineral phases within and around abundant vesicles. The third sample, a trachyte, shows relatively minor degrees of alteration in thin section. These groundmass separates were divided into four splits and treated with a progressively stronger acid and for longer duration. One split from each rock was left untreated to act as a baseline. Of the other three splits from each sample, one was treated with a mild leach (1N HCl and 1N HNO3), one a strong leach (1N HCl, 1N HNO3, 6N HCl, and 3N HNO3), and lastly the strong leach performed twice. The samples were then handpicked to remove any remaining visible alteration. The untreated samples were picked as well, removing the most distinctly altered grains. All splits were analyzed by electron microprobe, x-ray fluorescence (XRF) and the incremental heating 40Ar/39Ar dating method. We will report on the results of an image analysis of microprobe backscatter images and elemental maps taken of individual groundmass grains. This analysis will show the location

  16. Dating Violence

    ERIC Educational Resources Information Center

    Stader, David L.

    2011-01-01

    Dating violence is a form of student-on-student victimization and is a serious school safety issue. Research indicates that at a minimum, 10 percent of high school students are victims of dating violence in one form or another. Among female high school students that date, some data indicate that as many as 30 percent may be victims of dating…

  17. Age and correlation of a paleomagnetic episode in the western United States by Ar-40/Ar-39 dating and tephrochronology: The Jamaica, Blake, or a new polarity episode?

    NASA Astrophysics Data System (ADS)

    Herrero-Bervera, Emilio; Helsley, C. E.; Sarna-Wojcicki, A. M.; Lajoie, K. R.; Meyer, C. E.; McWilliams, M. O.; Negrini, R. M.; Turrin, B. D.; Donnelly-Nolan, J. M.; Liddicoat, J. C.

    1994-12-01

    High-resolution paleomagnetic records from two sites near Pringle Falls, Oregon, are compared with similar records from Summer Lake, Oregon, approximately 170 km to the southeast: Paoha Island, in Mono Lake, approximately 660 km to the southeast and Benton Crossing, in Long Valley, approximately 700 km to the southeast, in east-central California. The sequences at Pringle Falls contain a distinctive coarse pumice-lapilli tephra layer which we have dated as 218 +/- 10 ka by Ar-40/Ar-39 step-heating of plagioclase feldspar. Stratigraphically, this tephra is closely associated with a suite of several other tephra layers that bracket the interval studied paleomagnetically. Each tephra layer is distinguished by the unique chemical composition of its volcanic glass shards. The pumice layer dated at Pringle Falls is correlated with layers at three of the other localities. Using all the tephra layers, we can correlate the lake stratigraphic sequences and associated paleomagnetic records among the four distant localities. Additional age control is obtained from a fifth locality at Tulelake in northern California, where the stratigraphic interval of interest is bracketed between approximately 171 +/- 43 and approximately 140 ka. Characteristics of the paleomagnetic records indicate virtually identical paleofield variation, particularly the geometry of a normal to normal (N-N) geomagnetic polarity episode. The observed paleofield behavior resembles the Blake geomagnetic polarity episode, but is significantly older than the generally accepted age of the Blake episode. Either the age of the Blake episode is significantly underestimated, or the polarity episode documented here is older, perhaps the Jamaica episode, or is an as yet unreported episode. A corollary of the latter option is that paleomagnetic polarity episodes of different ages may have similar transition polar paths, a conclusion implying that a common mechanism is involved.

  18. The SEEDS High-Contrast Imaging Survey: Exoplanet and Brown Dwarf Survey for Nearby Young Stars Dated with Gyrochronology and Activity Age Indicators

    NASA Astrophysics Data System (ADS)

    Kuzuhara, Masayuki; Tamura, Motohide; Helminiak, Kris; Mede, Kyle; Brandt, Timothy; Janson, Markus; Kandori, Ryo; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Hashimoto, Jun

    2015-12-01

    The SEEDS campaign has successfully discovered and characterized exoplanets, brown dwarfs, and circumstellar disks since it began in 2009, via the direct imaging technique. The survey has targeted nearby young stars, as well as stars associated to star-forming regions, the Pleiades open cluster, moving groups, and debris disks. We selected the nearby young stars that have been dated with age indicators based on stellar rotation periods (i.e., gyrochronology) and chromoshperic/coronal activities. Of these, nearly 40 were observed, with ages mainly between 100 and 1000 Myr and distances less than 40 pc. Our observations typically attain the contrast of ~6 x 10-6 at 1'' and better than ~1 x 10-6 beyond 2'', enabling us to detect a planetary-mass companion even around such old stars. Indeed, the SEEDS team reported the discovery that the nearby Sun-like star GJ 504 hosts a Jovian companion GJ 504b, which has a mass of 3-8.5 Jupiter masses that is inferred according to the hot-start cooling models and our estimated system age of 100-510 Myr. The remaining observations out of the selected ~40 stars have resulted in no detection of additional planets or brown dwarf companions. Meanwhile, we have newly imaged a low-mass stellar companion orbiting the G-type star HIP 10321, for which the presence of companion was previously announced via radial velocity technique. The astrometry and radial velocity measurements are simultaneously analyzed to determine the orbit, providing constraints on the dynamical mass of both objects and stellar evolution models. Here we summarize our direct imaging observations for the nearby young stars dated with gyrochrolorogy and activity age indicators. Furthermore, we report the analysis for the HIP 10321 system with the imaged low-mass companion.

  19. Dating stratified settlement sites at Kom K and Kom W: Fifth millennium BCE radiocarbon ages for the Fayum Neolithic

    NASA Astrophysics Data System (ADS)

    Wendrich, W.; Taylor, R. E.; Southon, J.

    2010-04-01

    The earliest evidence of the use of domesticated plants, a traditional hallmark of Neolithic societies in the ancient Near East, first appears in Egypt in archaeological sites in the Fayum depression. Due to wind erosion often resulting in deflation of sediments in this region, stratified sites containing organic materials are rare and the depositional contexts of some earlier 14C measurements on Fayum Neolithic materials are not precisely documented. We report the results of 29 AMS-based 14C determinations on charcoal recovered from stratified contexts in two Fayum Neolithic village sites, Kom K and Kom W. These data assign a mid-5th millennium BCE age to these sites and permit an estimate of the length of their occupation to be approximately three centuries.

  20. Neovascular age-related macular degeneration without drusen in the fellow eye: clinical spectrum and therapeutic outcome

    PubMed Central

    Chung, Wing H; van Dijk, Elon H C; Mohabati, Danial; Dijkman, Greet; Yzer, Suzanne; de Jong, Eiko K; Fauser, Sascha; Schlingemann, Reinier O; Hoyng, Carel B; Boon, Camiel J F

    2017-01-01

    Purpose To investigate the clinical characteristics and therapeutic outcome of patients with neovascular age-related macular degeneration (nAMD) in 1 eye, without drusen in the fellow eye. Patients and methods Medical records of 381 patients were analyzed to identify the cases. The main outcomes included Early Treatment Diabetic Retinopathy Study (ETDRS) best-corrected visual acuity (BCVA) and change in central retinal thickness (CRT). These parameters were reviewed at baseline, first follow-up visit, and after 6, 12, and 24 months. Results Out of 381 patients, 29 cases (8%) were included (of whom 3 had polypoidal choroidal vasculopathy [PCV]) who were treated with anti-vascular endothelial growth factor (anti-VEGF) therapy which was supplemented by photodynamic therapy (PDT) in the PCV patients. Overall, no statistically significant change in mean BCVA was observed during follow-up. BCVA improved or remained stable (defined as a gain in BCVA, a stable BCVA, or a loss of <5 ETDRS letters) in 22 patients (76%), and 7 patients (23%) had lost ≥5 ETDRS letters at final follow-up. A gain of ≥15 ETDRS letters at final follow-up was seen in 5 patients (17%). Mean CRT had decreased significantly with 99 µm (P<0.001) at 24 months after the initial visit. Conclusion There is a clinical spectrum of nAMD that is not associated with drusen in the fellow eye. Patients with nAMD without drusen in the fellow eye respond to anti-VEGF treatment and, in cases of PCV, to supplemental PDT. The pathophysiology of this spectrum of nAMD may be different from drusen-associated age-related macular degeneration. PMID:28053502

  1. Dating the Vinland Map

    ScienceCinema

    None

    2016-07-12

    Scientists from Brookhaven National Laboratory, the University of Arizona, and the Smithsonian Institution used carbon-dating technology to determine the age of a controversial parchment that might be the first-ever map of North America.

  2. Dating the Vinland Map

    SciTech Connect

    2013-01-04

    Scientists from Brookhaven National Laboratory, the University of Arizona, and the Smithsonian Institution used carbon-dating technology to determine the age of a controversial parchment that might be the first-ever map of North America.

  3. Using chemical, hydrologic, and age dating analysis to delineate redox processes and flow paths in the riparian zone of a glacial outwash aquifer-stream system

    USGS Publications Warehouse

    Puckett, L.J.; Cowdery, T.K.; McMahon, P.B.; Tornes, L.H.; Stoner, J.D.

    2002-01-01

    A combination of chemical and dissolved gas analyses, chlorofluorocarbon age dating, and hydrologic measurements were used to determine the degree to which biogeochemical processes in a riparian wetland were responsible for removing NO3- from groundwaters discharging to the Otter Tail River in west central Minnesota. An analysis of river chemistry and flow data revealed that NO3- concentrations in the river increased in the lower half of the 8.3 km study reach as the result of groundwater discharge to the river. Groundwater head measurements along a study transect through the riparian wetland revealed a zone of groundwater discharge extending out under the river. On the basis of combined chemical, dissolved gas, age date, and hydrologic results, it was determined that water chemistry under the riparian wetland was controlled largely by upgradient groundwaters that followed flow paths up to 16 m deep and discharged under the wetland, creating a pattern of progressively older, more chemically reduced, low NO3- water the farther one progressed from the edge of the wetland toward the river. These findings pose challenges for researchers investigating biogeochemical processes in riparian buffer zones because the progressively older groundwaters entered the aquifer in earlier years when less NO3- fertilizer was being used. NO3- concentrations originally present in the groundwater had also decreased in the upgradient aquifer as a result of denitrification and progressively stronger reducing conditions there. The resulting pattern of decreasing NO3- concentrations across the riparian zone may be incorrectly interpreted as evidence of denitrification losses there instead of in the upgradient aquifer. Consequently, it is important to understand the hydrogeologic setting and age structure of the groundwaters being sampled in order to avgid misinterpreting biogeochemical processes in riparian zones.

  4. Reducing Maladaptive Behaviors in Preschool-Aged Children with Autism Spectrum Disorder Using the Early Start Denver Model

    PubMed Central

    Fulton, Elizabeth; Eapen, Valsamma; Črnčec, Rudi; Walter, Amelia; Rogers, Sally

    2014-01-01

    The presence of maladaptive behaviors in young people with autism spectrum disorder (ASD) can significantly limit engagement in treatment programs, as well as compromise future educational and vocational opportunities. This study aimed to explore whether the Early Start Denver Model (ESDM) treatment approach reduced maladaptive behaviors in preschool-aged children with ASD in a community-based long day care setting. The level of maladaptive behavior of 38 children with ASD was rated using an observation-based measure on three occasions during the intervention: on entry, 12 weeks post-entry, and on exit (post-intervention) over an average treatment duration of 11.8 months. Significant reductions were found in children’s maladaptive behaviors over the course of the intervention, with 68% of children showing a treatment response by 12 weeks and 79% on exit. This change was accompanied by improvement in children’s overall developmental level as assessed by the Mullen scales of early learning, but not by significant changes on the Vineland Adaptive Behavior Scales-II or Social Communication Questionnaire. Replication with a larger sample, control conditions, and additional measures of maladaptive behavior is necessary in order to determine the specific factors underlying these improvements; however, the findings of the present study suggest that the ESDM program may be effective in improving not only core developmental domains, but also decreasing maladaptive behaviors in preschool-aged children with ASD. PMID:24847474

  5. Using the BASC-2 Parent Rating Scales to Screen for Autism Spectrum Disorder in Toddlers and Preschool-Aged Children.

    PubMed

    Bradstreet, Lauren E; Juechter, Julia I; Kamphaus, Randy W; Kerns, Connor M; Robins, Diana L

    2017-02-01

    Early identification of toddlers and preschool-aged children with autism spectrum disorder (ASD) is important for ensuring that these youth receive targeted early intervention services. Identifying young children with ASD is complicated by overlap among symptoms of ASD and other developmental delays. Additionally, youth with ASD have a higher risk of experiencing co-occurring challenging behaviors that are beyond the diagnostic criteria for ASD (e.g., attention difficulties, anxiety). Given this, broadband behavioral assessments that measure symptoms of ASD as well as other behavioral and emotional challenges offer a cost-effective method for screening young children. The present study evaluated the utility of one such assessment, the Behavior Assessment System for Children, Second Edition, Parent Rating Scale-Preschool (BASC-2 PRS-P), for identifying young children with ASD from those with other diagnoses (including other developmental delays) and those without diagnoses. The sample included 224 toddlers and preschoolers (age range: 24-63 months, males n = 153 [68 % total sample]) who screened positive on an ASD-specific screening tool. Results demonstrated that the Developmental Social Disorders (DSD) scale on the BASC-2 PRS-P had adequate sensitivity and specificity values when distinguishing youth with ASD from those without any diagnoses, but not when differentiating between youth with ASD and those with other diagnoses. Similar to other multidimensional behavior rating scales, the BASC-2 PRS-P may be most useful for identifying young children who require comprehensive diagnostic evaluations.

  6. Impact of the presence of auditory neuropathy spectrum disorder (ANSD) on outcomes of children at three years of age

    PubMed Central

    Ching, Teresa Y. C.; Day, Julia; Dillon, Harvey; Gardner-Berry, Kirsty; Hou, Sanna; Seeto, Mark; Wong, Angela; Zhang, Vicky

    2013-01-01

    Objective To determine the influence of the presence of auditory neuropathy spectrum disorder (ANSD) on speech, language, and psycho-social development of children at three years of age. Design A population-based, longitudinal study was performed on outcomes of children with hearing impairment (LOCHI) in Australia. The demographic characteristics of the children were described, and their developmental outcomes were evaluated at three years of age. Performance of children with ANSD was compared with that of children without ANSD in the LOCHI study. Study sample There were 47 children with ANSD in the study sample. Results Sixty-four percent of children with ANSD have hearing sensitivity loss ranging from mild to severe degree, and the remaining have profound hearing loss. At three years, 27 children used hearing aids, 19 used cochlear implants, and one child did not use any hearing device. Thirty percent of children have disabilities in addition to hearing loss. On average, there were no significant differences in performance level between children with and without ANSD. Also, the variability of scores was not significantly different between the two groups. Conclusions There was no significant difference in performance levels or variability between children with and without ANSD, both for children who use hearing aids, and children who use cochlear implants. PMID:24350696

  7. Early-type Galaxy Archeology: Ages, Abundance Ratios, and Effective Temperatures from Full-spectrum Fitting

    NASA Astrophysics Data System (ADS)

    Conroy, Charlie; Graves, Genevieve J.; van Dokkum, Pieter G.

    2014-01-01

    The stellar populations of galaxies hold vital clues to their formation histories. In this paper we present results based on modeling stacked spectra of early-type galaxies drawn from the Sloan Digital Sky Survey as a function of velocity dispersion, σ, from 90 km s-1 to 300 km s-1. The spectra are of extremely high quality, with typical signal-to-noise ratio of 1000 Å-1, and a wavelength coverage of 4000 Å -8800 Å. Our population synthesis model includes variation in 16 elements from C to Ba, a two-component star formation history, the shift in effective temperature, Δ T eff, of the stars with respect to a solar metallicity isochrone, and the stellar initial mass function, among other parameters. In our approach we fit the full optical spectra rather than a select number of spectral indices and are able to, for the first time, measure the abundances of the elements V, Cr, Mn, Co, and Ni from the integrated light of distant galaxies. Our main results are as follows: (1) light-weighted stellar ages range from 6-12 Gyr from low to high σ (2) [Fe/H] varies by less than 0.1 dex across the entire sample; (3) Mg closely tracks O, and both increase from ≈0.0 at low σ to ~0.25 at high σ Si and Ti show a shallower rise with σ, and Ca tracks Fe rather than O; (4) the iron peak elements V, Cr, Mn, and Ni track Fe, while Co tracks O, suggesting that Co forms primarily in massive stars; (5) C and N track O over the full sample and [C/Fe] and [N/Fe] exceed 0.2 at high σ and (6) the variation in Δ T eff with total metallicity closely follows theoretical predictions based on stellar evolution theory. This last result is significant because it implies that we are robustly solving not only for the detailed abundance patterns but also the detailed temperature distributions (i.e., isochrones) of the stars in these galaxies. A variety of tests reveal that the systematic uncertainties in our measurements are probably 0.05 dex or less. Our derived [Mg/Fe] and [O

  8. Radiocarbon Dating.

    PubMed

    Van Strydonck, Mark

    2016-04-01

    Although most historians and art historians consider the radiocarbon dating technique not to be very precise by their criteria, the method has gained much importance over the last decades. Radiocarbon dating is increasingly used in the field of textile research and old polychrome statues, but also objects made of ivory, stucco, paper, and parchment are dated with the technique. Especially after the introduction of the AMS technique, a boom of this type of research has been noticed.

  9. Radiocarbon dating accuracy improved

    NASA Astrophysics Data System (ADS)

    Scientists have extended the accuracy of carbon-14 (14C) dating by correlating dates older than 8,000 years with uranium-thorium dates that span from 8,000 to 30,000 years before present (ybp, present = 1950). Edouard Bard, Bruno Hamelin, Richard Fairbanks and Alan Zindler, working at Columbia University's Lamont-Doherty Geological Observatory, dated corals from reefs off Barbados using both 14C and uranium-234/thorium-230 by thermal ionization mass spectrometry techniques. They found that the two age data sets deviated in a regular way, allowing the scientists to correlate the two sets of ages. The 14C dates were consistently younger than those determined by uranium-thorium, and the discrepancy increased to about 3,500 years at 20,000 ybp.

  10. Late Pleistocene ages for the most recent volcanism and glacial-pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic 36Cl dating

    USGS Publications Warehouse

    Vazquez, Jorge A.; Woolford, Jeff M

    2015-01-01

    The Big Pine volcanic field is one of several Quaternary volcanic fields that poses a potential volcanic hazard along the tectonically active Owens Valley of east-central California, and whose lavas are interbedded with deposits from Pleistocene glaciations in the Sierra Nevada Range. Previous geochronology indicates an ∼1.2 Ma history of volcanism, but the eruption ages and distribution of volcanic products associated with the most-recent eruptions have been poorly resolved. To delimit the timing and products of the youngest volcanism, we combine field mapping and cosmogenic 36Cl dating of basaltic lava flows in the area where lavas with youthful morphology and well-preserved flow structures are concentrated. Field mapping and petrology reveal approximately 15 vents and 6 principal flow units with variable geochemical composition and mineralogy. Cosmogenic 36Cl exposure ages for lava flow units from the top, middle, and bottom of the volcanic stratigraphy indicate eruptions at ∼17, 27, and 40 ka, revealing several different and previously unrecognized episodes of late Pleistocene volcanism. Olivine to plagioclase-pyroxene phyric basalt erupted from several vents during the most recent episode of volcanism at ∼17 ka, and produced a lava flow field covering ∼35 km2. The late Pleistocene 36Cl exposure ages indicate that moraine and pluvial shoreline deposits that overlie or modify the youngest Big Pine lavas reflect Tioga stage glaciation in the Sierra Nevada and the shore of paleo-Owens Lake during the last glacial cycle.

  11. Strategies for potential age dating of fingerprints through the diffusion of sebum molecules on a nonporous surface analyzed using time-of-flight secondary ion mass spectrometry.

    PubMed

    Muramoto, Shin; Sisco, Edward

    2015-08-18

    Age dating of fingerprints could have a significant impact in forensic science, as it has the potential to facilitate the judicial process by assessing the relevance of a fingerprint found at a crime scene. However, no method currently exists that can reliably predict the age of a latent fingerprint. In this manuscript, time-of-flight secondary ion imaging mass spectrometry (TOF-SIMS) was used to measure the diffusivity of saturated fatty acid molecules from a fingerprint on a silicon wafer. It was found that their diffusion from relatively fresh fingerprints (t ≤ 96 h) could be modeled using an error function, with diffusivities (mm(2)/h) that followed a power function when plotted against molecular weight. The equation x = 0.02t(0.5) was obtained for palmitic acid that could be used to find its position in millimeters (where the concentration is 50% of its initial value or c0/2) as a function of time in hours. The results show that on a clean silicon substrate, the age of a fingerprint (t ≤ 96 h) could reliably be obtained through the extent of diffusion of palmitic acid.

  12. ALPHA SPECTROMETRIC EVALUATION OF SRM-995 AS A POTENTIAL URANIUM/THORIUM DOUBLE TRACER SYSTEM FOR AGE-DATING URANIUM MATERIALS

    SciTech Connect

    Beals, D.

    2011-12-06

    Uranium-233 (t{sub 1/2} {approx} 1.59E5 years) is an artificial, fissile isotope of uranium that has significant importance in nuclear forensics. The isotope provides a unique signature in determining the origin and provenance of uranium-bearing materials and is valuable as a mass spectrometric tracer. Alpha spectrometry was employed in the critical evaluation of a {sup 233}U standard reference material (SRM-995) as a dual tracer system based on the in-growth of {sup 229}Th (t{sub 1/2} {approx} 7.34E3 years) for {approx}35 years following radiochemical purification. Preliminary investigations focused on the isotopic analysis of standards and unmodified fractions of SRM-995; all samples were separated and purified using a multi-column anion-exchange scheme. The {sup 229}Th/{sup 233}U atom ratio for SRM-995 was found to be 1.598E-4 ({+-} 4.50%) using recovery-corrected radiochemical methods. Using the Bateman equations and relevant half-lives, this ratio reflects a material that was purified {approx} 36.8 years prior to this analysis. The calculated age is discussed in contrast with both the date of certification and the recorded date of last purification.

  13. Schmidt-hammer exposure-age dating (SHD) of Lateglacial rock glacier systems near the eastern margin of the European Alps

    NASA Astrophysics Data System (ADS)

    Kellerer-Pirklbauer, Andreas

    2016-04-01

    Rock glaciers are widespread permafrost landforms in Austria. Various rock glacier inventories list more than 4500 rock glaciers in the country; some 30-40% of them are intact. Relict (permafrost free) and pseudo-relict rock glaciers (sporadic and isolated permafrost particularly near the root zone) prevail in number. Rock glaciers are commonly formed over a period of several ka. Dating such landforms helps to understand palaeoclimatic conditions. In this study three rock glaciers consisting of gneiss were dated applying the Schmidt-hammer exposure-age dating (SHD) method. The rock glaciers are located at three neighbouring cirques in the Seckauer Tauern Range named Reichart Rock Glacier (RRG, area 1.26 km², length 1800 m, elevation range 1520-1940 m a.s.l.), Schöneben Rock Glacier (SRG, 0.11 km², 750 m, 1715-1905 m a.s.l.), and Dürrtal Rock Glacier (DRG, 0.08 km², 850 m, 1750-1980 m a.s.l.). RRG is one of the largest rock glaciers in Austria. All three landforms are influenced by lenses of permafrost at present (as indicated by ERT). During the LGM the Seckauer Tauern were covered by valley glaciers and deglaciation occurred presumably already early in the Alpine Lateglacial period. An analogue N-type Schmidt-hammer (proceq) was used for measuring the surface strength of stable blocks at the rock glacier surface by recording a rebound value (R-value) of a spring-loaded bolt. The R-value gives a relative measure of the surface hardness and hence time since exposure to weathering. Eight (RRG) or six (SRG, DRG) Schmidt-hammer measurement sites (with 50-100 individual readings) aligned along longitudinal transects (=former central flow line) between a talus slope (with relatively fresh boulders) in the root zone and the frontal ridge were measured. Mean R-value differences of 30.5 at RRG, 25.1 at SRG, and 20.7 at DRG were revealed along the three transects. The differences between the lowest and the highest R-value at the rock glaciers itself were 19.0 at RRG, 15

  14. Precise Crystallization Age of the Bushveld Complex, South Africa: Direct Dating of the Platiniferous Merensky Reef Using the Zircon U-Pb Chemical Abrasion ID-TIMS Technique

    NASA Astrophysics Data System (ADS)

    Scoates, J. S.; Friedman, R. M.

    2006-12-01

    Determining the age of the Bushveld Complex, the world's largest layered intrusion and host to the majority of the known resources of platinum group elements, chromium and vanadium, has been difficult given the very low abundance of U-bearing minerals in the ultramafic-mafic cumulate rocks that comprise the body. This study provides a precise crystallization age for this giant layered intrusion and associated PGE mineralization, and allows for a re-evaluation of the duration and areal extent of Bushveld-related magmatic activity. Abundant, clear and colorless, anhedral zircon grains were separated from a sample of pegmatoidal feldspathic orthopyroxenite collected from the Merensky Reef in the West Mine (Townlands Shaft), Rustenburg Section. Low-U (21-105 ppm) zircon occurs with interstitial biotite and is locally directly in contact with sulfide. The zircon grains were subjected to different pre-treatment methods (no pre-treatment, air abrasion, and chemical abrasion [CA]) and isotope ratios for individual grains were analyzed by ID-TIMS. U-Pb data for the unabraded and air-abraded grains, and leachates from the CA procedure, are slightly discordant (0.1-1.6%) and yield overlapping 207Pb/206Pb dates ranging from 2052.5 to 2058.9 Ma. For the CA zircon grains (n=6), all data are concordant and give a Concordia age of 2054.3 ± 2.5 Ma (2sd, decay-constant errors included), which is interpreted as the age of crystallization of the Merensky Reef. This age is within error of published ages for the overlying, and locally cross-cutting, Bushveld or Lebowa granite suite, which implies that the entire Bushveld Complex was emplaced within a 2-3 myr interval. Comparison with ages from satellite intrusions (e.g. Moshaneng, Botswana; Uitkomst, South Africa) indicates that the Bushveld magmatic event at ca. 2054 Ma was regionally extensive across the northern Kaapvaal Craton and is consistent with relatively rapid emplacement of mantle-derived magmas along the Thabazimbi

  15. Episodes of brittle deformation within the Dien Bien Phu Fault zone, Vietnam: Evidence from K-Ar age dating of authigenic illite

    NASA Astrophysics Data System (ADS)

    Bui, Hoang Bac; Ngo, Xuan Thanh; Khuong, The Hung; Golonka, Jan; Nguyen, Tien Dung; Song, Yungoo; Itaya, Tetsumaru; Yagi, Koshi

    2017-01-01

    Constraining the timing of fault zone origin and movement history is of fundamental geotectonic importance to understand the evolution and processes of the brittle fault structures. The authors present in this paper authigenic illite K-Ar age data from the fault gouge samples, collected from the Dien Bien Phu Fault (DBPF) in the Dien Bien province, Vietnam as well as in a major strike-slip fault zone in South-East Asia; all of which played important roles in the structural formation and geotectonic development of northwestern Vietnam. The gouge fault samples were separated into four grain-size fractions (< 0.1 μm, 0.1-0.4 μm, 0.4-1.0 μm and 1.0-2.0 μm). The K-Ar ages of the fractions were divided into two age groups, from 26 to 29 Ma and 130 Ma. The timing of the fault movements is defined at 26 ± 0.24 Ma, 29 ± 0.61 Ma, 130.1 ± 1.27 Ma and 130.7 ± 1.29 Ma. This indicates that the Dien Bien Phu Fault underwent two movements, first in the Early Cretaceous, with an age of about 130 Ma and second in the Oligocene (Paleogene), with an age of about 26-29 Ma. The ductile deformation of the DBPF terminated during the Early Cretaceous. These studies also indicate slow exhumation of the Dien Bien granitoid complex during the Cretaceous times. The Oligocene ages indicate that the DBPF had been reactivated by the SE extrusion and clock-wise rotation of the Indochina block, caused by the collision of the Indian and Eurasian plates. This tectonic event led to the DBPF brittle-sinistral movement, causing the exhumation phase along the fault. This movement period (ca. 26-29 Ma) is coexistent with 600-700 km sinistral shearing along the Red River-Ailao Shan fault. This is the first report determining the absolute age constraints of multi-activated tectonic events, affecting the Dien Bien Phu Fault using the K-Ar dating method for the gouge samples.

  16. The effects of gender and age on repetitive and/or restricted behaviors and interests in adults with autism spectrum disorders and intellectual disability.

    PubMed

    Hattier, Megan A; Matson, Johnny L; Tureck, Kimberly; Horovitz, Max

    2011-01-01

    Frequency of repetitive and/or restricted behaviors and interests (RRBIs) was assessed in 140 adults with autism spectrum disorders (ASDs) and severe or profound intellectual disability (ID). The associations of gender and age range were analyzed with RRBI frequency which was obtained using the Stereotypies subscale of the Diagnostic Assessment for the Severely Handicapped-II (DASH-II). A significant main effect of gender was found. Male participants had higher frequency of RRBIs than females regardless of age range. There was not a significant main effect of age range or a significant interaction between gender and age range. Results and implications are discussed.

  17. Prediction of the impact of nonpoint sources on a drinking production well field using 85Kr, 39Ar and 3H/3He age dating

    NASA Astrophysics Data System (ADS)

    Broers, H.; Visser, A.; Heerdink, R.; Marsman, A.

    2011-12-01

    Nonpoint agricultural source pollution threatens drinking water supply in the Netherlands. The water quality of a drinking water production well field is determined by the land use in the capture area, geochemistry of the aquifer and the travel time distributions of the production wells. The aim of our study was to project the water quality of the production well field Holten (The Netherlands) based solely on the travel time distributions of the production wells and water quality data from the monitoring network in the vicinity of the well field. The Holten production wells are located in the east of the Netherlands, in sandy ice-pushed ridges. The travel time distributions of 4 shallow production wells (15-45 m below surface) and 3 deep production wells (45-70 m below surface) have been determined by a combination of 85Kr, 3H/3He and 39Ar dating. Sampled groundwater from 9 monitoring wells (27 screens) has been dated with 3H/3He to relate the water quality data to the time of recharge. Water quality data from the monitoring network provided the regional aggregated trend in water quality parameters, related to the time of recharge. These trends generally show an increase in agricultural contamination up to the 1980s, but decreasing concentrations in younger water. The regional aggregated trend of nitrate shows complete denitrification in groundwater older than 15 years. Excess N2 coincides with elevated sulfate concentrations, demonstrating denitrification by pyrite oxidation. The regional aggregated trends from the monitoring wells provided the source input for the water quality prognosis based on the travel time distributions of the production wells. Shallow production wells with a large young component are projected to show water quality improvements in the near future, while production wells with intermediate age distributions respond slower. The three deep wells produce a mixture of groundwater containing both young and very old water. These are projected to

  18. The Hamburg/ESO R-process enhanced star survey (HERES). IV. Detailed abundance analysis and age dating of the strongly r-process enhanced stars CS 29491-069 and HE 1219-0312

    NASA Astrophysics Data System (ADS)

    Hayek, W.; Wiesendahl, U.; Christlieb, N.; Eriksson, K.; Korn, A. J.; Barklem, P. S.; Hill, V.; Beers, T. C.; Farouqi, K.; Pfeiffer, B.; Kratz, K.-L.

    2009-09-01

    We report on a detailed abundance analysis of two strongly r-process enhanced, very metal-poor stars newly discovered in the HERES project, CS 29491-069 ([Fe/H]=-2.51, [r/Fe]=+1.1) and HE 1219-0312 ([Fe/H]=-2.96, [r/Fe]=+1.5). The analysis is based on high-quality VLT/UVES spectra and MARCS model atmospheres. We detect lines of 15 heavy elements in the spectrum of CS 29491-069, and 18 in HE 1219-0312; in both cases including the Th II 4019 Å line. The heavy-element abundance patterns of these two stars are mostly well-matched to scaled solar residual abundances not formed by the s-process. We also compare the observed pattern with recent high-entropy wind (HEW) calculations, which assume core-collapse supernovae of massive stars as the astrophysical environment for the r-process, and find good agreement for most lanthanides. The abundance ratios of the lighter elements strontium, yttrium, and zirconium, which are presumably not formed by the main r-process, are reproduced well by the model. Radioactive dating for CS 29491-069 with the observed thorium and rare-earth element abundance pairs results in an average age of 9.5 Gyr, when based on solar r-process residuals, and 17.6 Gyr, when using HEW model predictions. Chronometry seems to fail in the case of HE 1219-0312, resulting in a negative age due to its high thorium abundance. HE 1219-0312 could therefore exhibit an overabundance of the heaviest elements, which is sometimes called an “actinide boost”. Based on observations collected at the European Southern Observatory, Paranal, Chile (Proposal Number 170.D-0010). Table 8 is only available in electronic form at http://www.aanda.org

  19. Gender Ratio in a Clinical Population Sample, Age of Diagnosis and Duration of Assessment in Children and Adults with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Rutherford, Marion; McKenzie, Karen; Johnson, Tess; Catchpole, Ciara; O'Hare, Anne; McClure, Iain; Forsyth, Kirsty; McCartney, Deborah; Murray, Aja

    2016-01-01

    This article reports on gender ratio, age of diagnosis and the duration of assessment procedures in autism spectrum disorder diagnosis in a national study which included all types of clinical services for children and adults. Findings are reported from a retrospective case note analysis undertaken with a representative sample of 150 Scottish…

  20. The Effects of Gender and Age on Repetitive and/or Restricted Behaviors and Interests in Adults with Autism Spectrum Disorders and Intellectual Disability

    ERIC Educational Resources Information Center

    Hattier, Megan A.; Matson, Johnny L.; Tureck, Kimberly; Horovitz, Max

    2011-01-01

    Frequency of repetitive and/or restricted behaviors and interests (RRBIs) was assessed in 140 adults with autism spectrum disorders (ASDs) and severe or profound intellectual disability (ID). The associations of gender and age range were analyzed with RRBI frequency which was obtained using the Stereotypies subscale of the "Diagnostic…

  1. "Superheroes Social Skills": An Initial Study Examining an Evidence-Based Program for Elementary-Aged Students with Autism Spectrum Disorders in a School Setting

    ERIC Educational Resources Information Center

    Block, Heidi Marie

    2012-01-01

    The current study evaluated the effectiveness of a multimedia social skills program, Superheroes Social Skills for Children with Autism, in increasing the social engagement skills of 4 elementary-aged students with an autism spectrum disorder. This program incorporates several evidence-based practices into one comprehensive curriculum, namely…

  2. Lexical Processing in School-Age Children with Autism Spectrum Disorder and Children with Specific Language Impairment: The Role of Semantics

    ERIC Educational Resources Information Center

    Haebig, Eileen; Kaushanskaya, Margarita; Weismer, Susan Ellis

    2015-01-01

    Children with autism spectrum disorder (ASD) and specific language impairment (SLI) often have immature lexical-semantic knowledge; however, the organization of lexical-semantic knowledge is poorly understood. This study examined lexical processing in school-age children with ASD, SLI, and typical development, who were matched on receptive…

  3. Using a Hero as a Model in Video Instruction to Improve the Daily Living Skills of an Elementary-Aged Student with Autism Spectrum Disorder: A Pilot Study

    ERIC Educational Resources Information Center

    Ohtake, Yoshihisa

    2015-01-01

    The present pilot study investigated the impact of video hero modelling (VHM) on the daily living skills of an elementary-aged student with autism spectrum disorder. The VHM, in which a character much admired by the student exhibited a correct response, was shown to the participant immediately before the situation where he needed to exhibit the…

  4. Paleo-Environment and C-14 Dating: The Key to the Depositional Age of the Tha Chang and Related Sand Pits, Northeastern Thailand

    NASA Technical Reports Server (NTRS)

    Putthapiban, P.; Zolensky, M.; Jull, T.; Demartino, M.; Salyapongse, S.

    2012-01-01

    Tha Chang sand pits, Nakhon Ratchasima Province and many other sand pits in the area adjacent to the Mun River are characterized by their fluviatile environment in association with mass wasting deposits, along the paleo-river channel and the flood plain of the Mun River. Sediments of these deposits are characterized by clasts of various rock types especially the resistant ones with frequent big tree trunks, logs and wood fragments in different sizes and various stages of transformation from moldering stage to lignification and petrification. Widespread pyritization of the lower horizon suggests strongly reducing environment during burial. The Tha Chang deposits have been received much attention from geoscientists especially paleontologist communities, as they contain fragments of some distinct vertebrate species such as Stegadon sp., hominoid primate, rhinoceros Aceratherium and others. Based on the associated mammal fauna and hominoid fossils, the late Miocene ( 9 - 6 Ma) was given for the time of deposition of this sand and gravel unit. Some other reports believed that sediments and materials of these sand and gravel quarries (pits) were deposited by high-energy flood pulses contemporaneous with the tektites forming event during mid-Pleistocene at c. 0.8 Ma. Interpretation from Palynostratigraphical study suggested that the lower horizon of Tha Chang sand pit was deposited during Pliocene/Pleistocene period and the upper horizons are Pleistoncene/Holocene. It is crystal clear that all the fluviatile sediments including tektites and almost all fossil fragments being deposited in these sand pits were, likely a multiple times reworked materials. Only some old bamboo trees, some old crowling trees and fossils grasses observed on the old river bank are considered in situ. C-14 dating of 5 old wood specimens from Tha Chang Sand Pits, 15 old wood specimens from Chumpuang Sand Pits and one sample of old pottery from a Chumpuang Sand Pit were carried out in the NSF

  5. Age of most Recent Motion on the Western Denali Fault from Lichenometric Dating of a Large Rockfall Avalanche and Offset Moraines

    NASA Astrophysics Data System (ADS)

    Keskinen, M.; Beget, J.

    2005-12-01

    No major historic earthquakes are known to have occurred on the portion of the Denali Fault lying west of the 7.9 M 2002 rupture zone. The 2002 earthquake produced large rockfall avalanches at several locations within a few kilometers of the 2002 fault trace. Panorama Mountain lies 60 km west of the limit of the 2002 fault zone, and just 4 km off the trend of the western Denali Fault. The west face of Panorama Mountain was the source of a large prehistoric rockfall avalanche that traveled 2 km across the Nenana River, covering an area of ca. 8 km2. The rockfall avalanche deposit consists of fractured blocks as much as 7 m high in a finer, comminuted matrix. Lichenometric dating of the rockfall avalanche based on the central Alaska Range lichen curve of Beget (1991) indicates this rockfall occurred about 300-500 years ago. This is similar to a lichenometric date on an ice-cored moraine offset >5m by the Denali Fault 40 km to the west near Mt. McKinley. The "Bains Creek fault" lies only 1 km south of Panorama Peak, and although Pleistocene glacial deposits are offset by this fault in an exposure along the Parks Highway, we found no evidence this fault was active in the Holocene. In contrast, there is good agreement between the age of offset moraines on the main, active strand of the Denali Fault near Mt. McKinley and the rockfall avalanche deposit near Panorama Mountain. This suggests the most recent large earthquake on the western Denali Fault occurred ca. 300-500 years ago. If the long-term slip rate on the western Denali Fault is ca. 1 cm/yr, i.e. similar to the slip rate inferred for the portion that broke in the 2002 event, then at least several meters of strain have accumulated since the last seismic event.

  6. Age-related differences in the association between stereotypic behaviour and salivary cortisol in young males with an Autism Spectrum Disorder.

    PubMed

    Bitsika, Vicki; Sharpley, Christopher F; Agnew, Linda L; Andronicos, Nicholas M

    2015-12-01

    To identify if age influenced the relationship between one of the central symptoms of Autism Spectrum Disorder (ASD) and physiological stress, the association between stereotypic behaviour (SB) and stress-related cortisol concentrations was examined in a sample of 150 young males with an ASD. Parent-rated SB was significantly correlated with cortisol concentrations for boys aged 6 years to 12 years but not for adolescents aged 13 years to 18 years. This age-related difference in this association was not a function of cortisol concentrations but was related to differences in SB across these two age groups. IQ did not have a significant effect on this relationship, suggesting that age-related learning may have been a possible pathway for reduced SB during adolescence. The aspect of SB that was most powerfully related to cortisol was general repetitive behaviour rather than movements of specific body parts. Explanations of these findings are raised for further investigation.

  7. A Screening Questionnaire for Asperger Syndrome and Other High-Functioning Autism Spectrum Disorders in School Age Children.

    ERIC Educational Resources Information Center

    Ehlers, Stephan; Gillberg, Christopher; Wing, Lorna

    1999-01-01

    Presents data on the High-Functioning Autism Spectrum Screening Questionnaire, a 27-item checklist for completion by lay informants when assessing symptoms characteristic of Asperger syndrome and other high-functioning autism spectrum disorders in children and adolescents with normal intelligence or mild mental retardation. Reliability and…

  8. Sex Role and Dating Orientation.

    ERIC Educational Resources Information Center

    McCabe, M. P.; Collins, J. K.

    1979-01-01

    Male and female subjects from three age groups completed questionnaires on sex roles and dating orientations. Males approached dating from both a psychoaffectional and psychobiological orientation, while females approached it from a psychoaffectional orientation. Significant differences were found in dating attitudes between male and female…

  9. Optical-Ultraviolet Spectrum and Proper Motion of the Middle-aged Pulsar B1055-52

    NASA Astrophysics Data System (ADS)

    Mignani, R. P.; Pavlov, G. G.; Kargaltsev, O.

    2010-09-01

    PSR B1055-52 is a middle-aged (τ = 535 kyr) radio, X-ray, and γ-ray pulsar showing X-ray thermal emission from the neutron star (NS) surface. A candidate optical counterpart to PSR B1055-52 was proposed by Mignani and coworkers based on Hubble Space Telescope (HST) observations performed in 1996, in one spectral band only. We report on HST observations of this field carried out in 2008, in four spectral bands. The astrometric and photometric analyses of these data confirm the identification of the proposed candidate as the pulsar's optical counterpart. Similar to other middle-aged pulsars, its optical-UV spectrum can be described by the sum of a power-law (PLO) component (F_{ν} ∝ ν^{-α_O}), presumably emitted from the pulsar magnetosphere, and a Rayleigh-Jeans (RJ) component emitted from the NS surface. The spectral index of the PLO component, αO = 1.05 ± 0.34, is larger than for other pulsars with optical counterparts. The RJ component, with a brightness temperature T O = (0.66 ± 0.10) d 2 350 R -2 O,13 MK (where d 350 and R O,13 are the distance to the pulsar in units of 350 pc and the radius of the emitting area in units of 13 km, respectively), shows a factor of 4 excess with respect to the extrapolation of the X-ray thermal component into the UV-optical. This hints that the RJ component is emitted from a larger, colder area, and suggests that the distance to the pulsar is smaller than previously thought. From absolute astrometry of the HST images, we measured the pulsar coordinates with a position accuracy of 0farcs15. From comparison with previous observations, we measured the pulsar proper motion, μ = 42 ± 5 mas yr-1, which corresponds to a transverse velocity Vt = (70 ± 8) d 350 km s-1. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under contract No. NAS 5-26555. Based on observations collected at the European Southern Observatory (ESO), La

  10. A screening questionnaire for Asperger syndrome and other high-functioning autism spectrum disorders in school age children.

    PubMed

    Ehlers, S; Gillberg, C; Wing, L

    1999-04-01

    The high-functioning Autism Spectrum Screening Questionnaire (ASSQ) is a 27-item checklist for completion by lay informants when assessing symptoms characteristic of Asperger syndrome and other high-functioning autism spectrum disorders in children and adolescents with normal intelligence or mild mental retardation. Data for parent and teacher ratings in a clinical sample are presented along with various measures of reliability and validity. Optimal cutoff scores were estimated, using Receiver Operating Characteristic analysis. Findings indicate that the ASSQ is a useful brief screening device for the identification of autism spectrum disorders in clinical settings.

  11. Screening accuracy of the parent-completed Ages and Stages Questionnaires - second edition as a broadband screener for motor problems in preschoolers with autism spectrum disorders.

    PubMed

    Vanvuchelen, Marleen; Van Schuerbeeck, Lise; Braeken, Marijke Aka

    2017-01-01

    Children with autism spectrum disorders are at risk for motor problems. However, this area is often overlooked in the developmental evaluation in autism diagnostic clinics. An alternative can be to identify children who should receive intensive motor assessment by using a parent-based screener. The aim of this study was to examine whether the Ages and Stages Questionnaires - second edition may be used to identify gross and fine motor problems in children. High-functioning children with autism spectrum disorder (n = 43, 22-54 m) participated in this study. Sensitivity, specificity, predictive values and areas under the receiver operating characteristic curve were calculated by comparing the Ages and Stages Questionnaires - second edition scores to the developmental evaluation of the Peabody Developmental Motor Scale - second edition. The results revealed that both the Ages and Stages Questionnaires - second edition gross and fine motor domain may be used to identify children without motor problems. In contrast, sensitivity analyses revealed the likelihood of under screening motor problems in this population. The Ages and Stages Questionnaires - second edition met only the criteria of a fair to good accuracy to identify poor gross motor (sensitivity = 100%) and below-average fine motor development (sensitivity = 71%) in this sample. Hence, the capacity of the Ages and Stages Questionnaires - second edition to identify motor problems in preschoolers with autism spectrum disorder appears to be limited. It is recommended to include a formal standardized motor test in the diagnostic procedure for all children with autism spectrum disorder.

  12. Ground water/surface water interactions in Lake Naivasha, Kenya, using delta 18O, delta D, and 3H/3He age-dating.

    PubMed

    Ojiambo, B S; Poreda, R J; Lyons, W B

    2001-01-01

    We have analyzed a series of ground water samples from the Lake Naivasha region, Kenya, for their helium isotopic composition. Lake Naivasha is unique among the East Africa Rift Valley lakes in that it is fresh. It has long been thought that the low salinity of this lake is due, in part, to rapid water loss from the lake into the local ground water system. Our results show that the Olkaria geothermal waters, south of the lake, are devoid of tritium and, thus, are more than 50 years old. An important implication of these results is that even if Olkaria geothermal reservoir water originated from Lake Naivasha, it has been underground for a long time, (> 50 years) and is not derived from present-day Lake Naivasha water. This flow time is of the same order of magnitude as conservative major solutes, such as chloride, as determined through residence time calculations. On the north side of Lake Naivasha, deep wells (91 m) have water approximately 20 years old. Water from these wells has stable isotopic values resembling those of nearby rivers, and high-elevation eastern Rift water. This indicates that this water recharges from rains from high eastern Rift Valley escarpments. Many of the shallow wells on the south side of the lake have 3H/3He ages between four and 17 years. The young ages and the delta 18 O-enriched signature of the water from these wells indicate that they are recharged by a mixture of water from the lake, Rift flanks, and water from deep pumping wells that is recharged during irrigation. Water mixing ratio calculations using delta 18O and delta D isotopes show that about 50% to 70% of the southern ground water system is derived from the lake, while the Olkaria geothermal reservoir water shows that 40% to 50% of this water is originally lake water. Calculated mean recharge rates range from 0.10 to 1.59 m/yr with a mean of 0.52 +/- 0.40 m/yr. Estimated horizontal velocity from 3H/3He age dating between Lake Naivasha and a well about 3 km to the south is

  13. Coupling 3D groundwater modeling with CFC-based age dating to classify local groundwater circulation in an unconfined crystalline aquifer

    NASA Astrophysics Data System (ADS)

    Kolbe, Tamara; Marçais, Jean; Thomas, Zahra; Abbott, Benjamin W.; de Dreuzy, Jean-Raynald; Rousseau-Gueutin, Pauline; Aquilina, Luc; Labasque, Thierry; Pinay, Gilles

    2016-12-01

    Nitrogen pollution of freshwater and estuarine environments is one of the most urgent environmental crises. Shallow aquifers with predominantly local flow circulation are particularly vulnerable to agricultural contaminants. Water transit time and flow path are key controls on catchment nitrogen retention and removal capacity, but the relative importance of hydrogeological and topographical factors in determining these parameters is still uncertain. We used groundwater dating and numerical modeling techniques to assess transit time and flow path in an unconfined aquifer in Brittany, France. The 35.5 km2 study catchment has a crystalline basement underneath a ∼60 m thick weathered and fractured layer, and is separated into a distinct upland and lowland area by an 80 m-high butte. We used groundwater discharge and groundwater ages derived from chlorofluorocarbon (CFC) concentration to calibrate a free-surface flow model simulating groundwater flow circulation. We found that groundwater flow was highly local (mean travel distance = 350 m), substantially smaller than the typical distance between neighboring streams (∼1 km), while CFC-based ages were quite old (mean = 40 years). Sensitivity analysis revealed that groundwater travel distances were not sensitive to geological parameters (i.e. arrangement of geological layers and permeability profile) within the constraints of the CFC age data. However, circulation was sensitive to topography in the lowland area where the water table was near the land surface, and to recharge rate in the upland area where water input modulated the free surface of the aquifer. We quantified these differences with a local groundwater ratio (rGW-LOCAL), defined as the mean groundwater travel distance divided by the mean of the reference surface distances (the distance water would have to travel across the surface of the digital elevation model). Lowland, rGW-LOCAL was near 1, indicating primarily topographical controls. Upland, r

  14. The Antarctica component of postglacial rebound model ICE-6G_C (VM5a) based on GPS positioning, exposure age dating of ice thicknesses, and relative sea level histories

    NASA Astrophysics Data System (ADS)

    Argus, Donald F.; Peltier, W. R.; Drummond, R.; Moore, Angelyn W.

    2014-07-01

    A new model of the deglaciation history of Antarctica over the past 25 kyr has been developed, which we refer to herein as ICE-6G_C (VM5a). This revision of its predecessor ICE-5G (VM2) has been constrained to fit all available geological and geodetic observations, consisting of: (1) the present day uplift rates at 42 sites estimated from GPS measurements, (2) ice thickness change at 62 locations estimated from exposure-age dating, (3) Holocene relative sea level histories from 12 locations estimated on the basis of radiocarbon dating and (4) age of the onset of marine sedimentation at nine locations along the Antarctic shelf also estimated on the basis of 14C dating. Our new model fits the totality of these data well. An additional nine GPS-determined site velocities are also estimated for locations known to be influenced by modern ice loss from the Pine Island Bay and Northern Antarctic Peninsula regions. At the 42 locations not influenced by modern ice loss, the quality of the fit of postglacial rebound model ICE-6G_C (VM5A) is characterized by a weighted root mean square residual of 0.9 mm yr-1. The Southern Antarctic Peninsula is inferred to be rising at 2 mm yr-1, requiring there to be less Holocene ice loss there than in the prior model ICE-5G (VM2). The East Antarctica coast is rising at approximately 1 mm yr-1, requiring ice loss from this region to have been small since Last Glacial Maximum. The Ellsworth Mountains, at the base of the Antarctic Peninsula, are inferred to be rising at 5-8 mm yr-1, indicating large ice loss from this area during deglaciation that is poorly sampled by geological data. Horizontal deformation of the Antarctic Plate is minor with two exceptions. First, O'Higgins, at the tip of the Antarctic Peninsula, is moving southeast at a significant 2 mm yr-1 relative to the Antarctic Plate. Secondly, the margins of the Ronne and Ross Ice Shelves are moving horizontally away from the shelf centres at an approximate rate of 0.8 mm yr-1, in

  15. Predicting social and communicative ability in school-age children with autism spectrum disorder: A pilot study of the Social Attribution Task, Multiple Choice.

    PubMed

    Burger-Caplan, Rebecca; Saulnier, Celine; Jones, Warren; Klin, Ami

    2016-11-01

    The Social Attribution Task, Multiple Choice is introduced as a measure of implicit social cognitive ability in children, addressing a key challenge in quantification of social cognitive function in autism spectrum disorder, whereby individuals can often be successful in explicit social scenarios, despite marked social adaptive deficits. The 19-question Social Attribution Task, Multiple Choice, which presents ambiguous stimuli meant to elicit social attribution, was administered to children with autism spectrum disorder (N = 23) and to age-matched and verbal IQ-matched typically developing children (N = 57). The Social Attribution Task, Multiple Choice performance differed between autism spectrum disorder and typically developing groups, with typically developing children performing significantly better than children with autism spectrum disorder. The Social Attribution Task, Multiple Choice scores were positively correlated with age (r = 0.474) while being independent from verbal IQ (r = 0.236). The Social Attribution Task, Multiple Choice was strongly correlated with Vineland Adaptive Behavior Scales Communication (r = 0.464) and Socialization (r = 0.482) scores, but not with Daily Living Skills scores (r = 0.116), suggesting that the implicit social cognitive ability underlying performance on the Social Attribution Task, Multiple Choice is associated with real-life social adaptive function.

  16. Screening for Autistic Spectrum Disorder in Children Aged 14-15 Months. II: Population Screening with the Early Screening of Autistic Traits Questionnaire (ESAT). Design and General Findings

    ERIC Educational Resources Information Center

    Dietz, Claudine; Swinkels, Sophie; van Daalen, Emma; van Engeland, Herman; Buitelaar, Jan K.

    2006-01-01

    A two-stage protocol for screening for autistic spectrum disorders (ASD) was evaluated in a random population of 31,724 children aged 14-15 months. Children were first pre-screened by physicians at well-baby clinics using a 4-item screening instrument. Infants that screened positive were then evaluated during a 1.5-h home visit by a trained…

  17. Principal component structuring of the non-REM Sleep EEG spectrum in older adults yields age-related changes in the sleep and wake drives.

    PubMed

    Putilov, Arcady A; Münch, Mirjam Y; Cajochen, Christian

    2013-12-01

    Age-related disturbances of the sleep-wake cycle can reflect ontogenetic changes in regulatory mechanisms underlying normal and pathological aging, but the exact nature of these changes remains unclear. The present report is the first attempt to apply principal component analysis to the electroencephalographic (EEG) spectrum to examine of whether the observed age-related changes in the objective sleep measures can be linked to the opponent sleep-promoting and wake-promoting processes. The EEG indicators of these processes--scores on the 1st and 2nd principal components of the EEG spectrum, respectively--were compared in 15 older (57-74 years) and 16 younger (20-31 years) healthy volunteers. The scores were calculated for non-REM sleep episodes which occurred during ten 75-min naps scheduled every 150 min throughout a 40-h constant routine protocol. Both, a decrease of the 1st principal component score and an increase of the 2nd principal component score were found to contribute to such most obvious age-related modification of the sleep EEG spectrum as attenuation of EEG slow-wave activity in older people. Therefore, we concluded that the normal aging process can reflect both a weakening of the sleep-promoting process and a strengthening of the wake-promoting process, respectively. Such bidirectional changes in chronoregulatory processes may explain why sleep of older people is characterized by the few profitable and a number of detrimental features (i.e., a better ability to cope with daytime sleepiness and sleep loss vs. difficulty of falling asleep, decreased total nighttime sleep, "lightened" and fragmentized sleep, unwanted early morning awakenings, etc.).

  18. Discrepancies between Academic Achievement and Intellectual Ability in Higher-Functioning School-Aged Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Estes, Annette; Rivera, Vanessa; Bryan, Matthew; Cali, Philip; Dawson, Geraldine

    2011-01-01

    Academic achievement patterns and their relationships with intellectual ability, social abilities, and problem behavior are described in a sample of 30 higher-functioning, 9-year-old children with autism spectrum disorder (ASD). Both social abilities and problem behavior have been found to be predictive of academic achievement in typically…

  19. Predicting Language and Social Outcomes at Age 5 for Later-Born Siblings of Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Malesa, Elizabeth; Foss-Feig, Jennifer; Yoder, Paul; Warren, Zachary; Walden, Tedra; Stone, Wendy L.

    2013-01-01

    The relation between early joint attention (in which a child coordinates attention between another person and an object or event) and later language and social outcomes was examined in younger siblings of children with autism spectrum disorder (Sibs-ASD) and younger siblings of children with typical development (Sibs-TD). Initial levels of joint…

  20. Aging and Autism Spectrum Disorder: A Naturalistic, Longitudinal Study of the Comorbidities and Behavioral and Neuropsychiatric Symptoms in Adults with ASD.

    PubMed

    Wise, Elizabeth A; Smith, Marcia D; Rabins, Peter V

    2017-03-16

    Little is known about Autism Spectrum Disorder (ASD) in persons over age 50. In a retrospective, naturalistic review of 74 individuals aged 30 and older meeting DSM-5 criteria for ASD, the point prevalence of behavioral and neuropsychiatric symptoms (BNPS) declined significantly for 12 of 13 BNPS over a mean of 25 years while many other features of ASD remained stable. GI disorders (68.9%) and seizure disorders (23%) were common, and 25.7% of the sample had a BMI >30. Females were more likely to engage in screaming (p < 0.05) and oppositional behavior (p < 0.05). Current age did not have a significant effect on BNPS prevalence.

  1. Suggested terminology for Quaternary dating methods

    USGS Publications Warehouse

    Colman, Steven M.; Pierce, K.L.; Birkeland, P.W.

    1987-01-01

    Classification of Quaternary dating methods should be based on the level of quantitative information and the degree of confidence contained in the age estimates produced by the dating methods. We recommend the use of the terms numerical-age, calibrated-age, relative-age, and correlated-age to describe these levels. We also classify dating methods by type into sideral, isotopic, radiogenic, chemical and biological, geomorphic, and correlation methods. The use of "absolute" is inappropriate for most dating methods, and should be replaced by "numerical." The use of "date" should be minimized in favor of "age" or "age estimate." We recommend use of the abbreviations ka and Ma for most ages; calender dates can be used where appropriate and yr B.P. can be used for radiocarbon ages. ?? 1987.

  2. Hemodynamic Correlates of Blood Pressure Across the Adult Age Spectrum: Noninvasive Evaluation in the Framingham Heart Study

    PubMed Central

    Mitchell, Gary F.; Wang, Na; Palmisano, Joseph N.; Larson, Martin G.; Hamburg, Naomi M.; Vita, Joseph A.; Levy, Daniel; Benjamin, Emelia J.; Vasan, Ramachandran S.

    2010-01-01

    Background Systolic blood pressure and pulse pressure are substantially higher in older adults. The relative contributions of increased forward versus reflected pressure wave amplitude or earlier arrival of the reflected wave to elevated pulse pressure remain controversial. Methods and Results We measured proximal aortic pressure and flow, forward pressure wave amplitude, global wave reflection, reflected wave timing and pulse wave velocity noninvasively in 6417 (age range, 19 to 90 years; 53% women) Framingham Heart Study Third Generation and Offspring participants. Variation in forward wave amplitude paralleled pulse pressure throughout adulthood. In contrast, wave reflection and pulse pressure were divergent across adulthood: in younger participants, pulse pressure was lower and wave reflection higher with advancing age whereas in older participants, pulse pressure was higher and wave reflection lower with age. Reflected wave timing differed modestly across age groups despite considerable differences in pulse wave velocity. Forward wave amplitude explained 80% (central) and 66% (peripheral) of the variance in pulse pressure in younger participants (<50 years) and 90% and 84% in the older participants (≥50 years, all P<0.0001). In a stepwise model that evaluated age-pulse pressure relations in the full sample, the late accelerated increases in central and peripheral pulse pressure were markedly attenuated when variation in forward wave amplitude was considered. Conclusions Higher pulse pressure at any age and higher pulse pressure with advancing age is predominantly associated with a larger forward pressure wave. The influence of wave reflection on age-related differences in pulse pressure was minor. PMID:20855656

  3. I-Xe Dating: Comparison of I-Xe and Pb-Pb Ages of Richardton Chondrules and Separated Mineral Phases

    NASA Technical Reports Server (NTRS)

    Pravdivtseva, O. V.; Amelin, Y.; Hohenberg, C. M.; Meshik, A. P.

    2002-01-01

    I-Xe and Pb-Pb ages of individual Richardton chondrules and different mineral phases were compared in order to test the absolute I-Xe age normalization. Additional information is contained in the original extended abstract.

  4. Dating slate belts using 40Ar/39Ar geochronology and zircon ages from crosscutting plutons: A case study from east-central Maine, USA

    NASA Astrophysics Data System (ADS)

    Ghanem, Hind; Kunk, Michael; Ludman, Allan; Bish, David; Wintsch, Robert

    2016-04-01

    Determining the tectonic significance of slate belts is a persistent problem in many orogenic belts because of the lack of time constraints on the age of deposition and the age(s) of cleavages. We have solved this problem in east-central Maine where the ages of the regional Acadian cleavage (S1) and local ductile fault zone cleavage (S2) were both constrained using 40Ar/39Ar geochronology and the ages of crosscutting plutons. Applying 40Ar/39Ar geochronology to rocks with multiple generations of muscovite was possible because each cleavage-forming muscovite records a crystallization age rather than a cooling age due to the low grade of regional metamorphism. Evidence for metamorphic crystallization in rocks dominated by regional Acadian cleavage (S1) comes from the truncations of detrital and authigenic muscovite and chlorite grains by new muscovite and chlorite grains that define the S1 foliation. In rocks that display two foliations, the evidence comes from the truncations of chlorite and muscovite grains defining all earlier fabrics by new muscovite grains in the younger folia (S2). Step-heating experiments using the 40Ar/39Ar technique on twelve samples all yielded sigmoidal age spectra. The low-temperature steps produced a hump in the age spectra, indicating 39Ar recoil into adjacent interlayered chlorite grains, the latter interlayering confirmed by back-scattered electron imaging. Continuing steps climbed steadily from those with minimum apparent ages as young as ~381 Ma to steps with maximum ages as old as 466 Ma. The samples with the lowest minimum apparent age steps are those in which the S2 cleavage-forming mica population dominates. In contrast, the oldest apparent age steps are from samples that have the highest modal abundance of detrital micas. The Middle Ordovician age of the maximum age steps is interpreted to be the minimum cooling age of the detrital micas. The minimum 40Ar/39Ar age steps of muscovite in the samples that display only S1 cleavage

  5. Dating human bone: is racemization dating species-specific?

    PubMed

    Moini, Mehdi; Rollman, Christopher M; France, Christine A M

    2013-12-03

    Our recently developed dating technique based on the racemization rate of aspartic acid was applied to dating human bone, as well as that of other mammals, utilizing capillary electrophoresis mass spectrometry. First, several well-dated (mostly (14)C-dated and with strong archeological evidence) human bones ranging in age from 150 to ~10,000 years were used to develop a calibration curve for human bone. The D/L ratio of aspartic acid for these specimens ranged from 2.4% to ~10%, with a correlation coefficient of better than 0.99, indicating a strong linear relationship between the d/l ratio of aspartic acid and the age of the specimens. This calibration curve can now be used to date human archeological specimens of unknown age, up to ~10,000 years. However, when the technique was applied to well-dated mixed species of larger mammal bones such as bison, whale, llama, etc., the calibration curve showed a slower rate of racemization with a lower correlation (0.88). As additional large mammal bones with less certain age (i.e., using archeological evidence alone with no (14)C-dating) were dated the correlation coefficient decreased to 0.70. The correlation coefficient decreased further to 0.58 when the racemization data from all mammals (including human) were added to the calibration curve, indicating the importance of using well-dated, species-specific specimens for forming a calibration curve. This conclusion is consistent with our previously published calibration curve for a single species of silk (Bombyx mori), which followed the expected reversible first-order kinetics. These results support species specificity of amino acid racemization dating.

  6. Age-Related Differences in Response to Music-Evoked Emotion Among Children and Adolescents with Autism Spectrum Disorders.

    PubMed

    Stephenson, K G; Quintin, E M; South, M

    2016-04-01

    While research regarding emotion recognition in ASD has focused primarily on social cues, musical stimuli also elicit strong emotional responses. This study extends and expands the few previous studies of response to music in ASD, measuring both psychophysiological and behavioral responses in younger children (ages 8-11) as well as older adolescents (ages 16-18). Compared to controls, the ASD group demonstrated reduced skin conductance response to music-evoked emotion. Younger groups, regardless of diagnosis, showed greater physiological reactivity to scary stimuli than to other emotions. There was a significant interaction of age group and diagnostic group in identifying scary music stimuli, possibly evidencing disrupted developmental trajectories in ASD for integrating physiological and cognitive cues that may underlie symptoms of anxiety.

  7. Characterization of depositional age and structure of sedimentary successions by U-Pb TIMS and LA-ICP-MS dating of volcanic horizons and detrital zircons: an example from the western Trondheim Nappe Complex, Scandinavian Caledonides

    NASA Astrophysics Data System (ADS)

    Gasser, Deta; Grenne, Tor; Corfu, Fernando; Eivind Augland, Lars

    2016-04-01

    Revealing the absolute depositional age of non-fossiliferous sedimentary successions represents a long-lasting challenge in Earth Sciences. Lacking age control hampers the correct interpretation of the temporal evolution of depositional systems, and, if deformed, of the architecture of fold-and-thrust belts. Dating of detrital zircons within clastic sedimentary successions has over the past decades become a popular method to approximate the absolute depositional age and to characterize the source areas of such rocks. If combined with other geochronological information, such as dating of contemporaneous volcanic horizons, a much better resolution of the stratigraphy and structure of non-fossiliferous sedimentary successions can be achieved. The western Trondheim nappe complex in the central Scandinavian Caledonides is a classical area in this respect. On top of Late Cambrian to Early Ordovician ophiolitic fragments, various volcanic, volcano-clastic and clastic successions tell a complex story of island-arc formation, ocean closure and continent collision. Several famous fossil horizons indicate deposition during the Middle to Upper Ordovician (ca. 470-445 Ma), but large areas lack an absolute age control and several contrasting stratigraphic schemes and structural interpretations have been presented in the past. In this contribution we present the results of LA-ICP-MS detrital U-Pb zircon dating of clastic horizons as well as U-Pb TIMS zircon dating of volcanic horizons and magmatic clasts in conglomerates in order to characterize the depositional age and structure of the western Trondheim nappe complex in more detail. Together with field observations, including way up criteria, the zircon data enable significant revisions of existing stratigraphic and structural models. At least four (volcano-)sedimentary successions can be distinguished above the ca. 480-485 Ma greenstones: (1) ca. 470-463 Ma shales, limestones and andesitic porphyrites (Hølonda and Fanabekken

  8. Anatomy and aging of the amygdala and hippocampus in autism spectrum disorder: an in vivo magnetic resonance imaging study of Asperger syndrome.

    PubMed

    Murphy, Clodagh M; Deeley, Q; Daly, E M; Ecker, C; O'Brien, F M; Hallahan, B; Loth, E; Toal, F; Reed, S; Hales, S; Robertson, D M; Craig, M C; Mullins, D; Barker, G J; Lavender, T; Johnston, P; Murphy, K C; Murphy, D G

    2012-02-01

    It has been proposed that people with autism spectrum disorder (ASD) have abnormal morphometry and development of the amygdala and hippocampus (AH). However, previous reports are inconsistent, perhaps because they included people of different ASD diagnoses, ages, and health. We compared, using magnetic resonance imaging, the in vivo anatomy of the AH in 32 healthy individuals with Asperger syndrome (12-47 years) and 32 healthy controls who did not differ significantly in age or IQ. We measured bulk (gray + white matter) volume of the AH using manual tracing (MEASURE). We first compared the volume of AH between individuals with Asperger syndrome and controls and then investigated age-related differences. We compared differences in anatomy before, and after, correcting for whole brain size. There was no significant between group differences in whole brain volume. However, individuals with Asperger syndrome had a significantly larger raw bulk volume of total (P<0.01), right (P<0.01), and left amygdala (P<0.05); and when corrected for overall brain size, total (P<0.05), and right amygdala (P<0.01). There was a significant group difference in aging of left amygdala; controls, but not individuals with Asperger syndrome, had a significant age-related increase in volume (r = 0.486, P<0.01, and r = 0.007, P = 0.97, z = 1.995). There were no significant group differences in volume or age-related effects in hippocampus. Individuals with Asperger syndrome have significant differences from controls in bulk volume and aging of the amygdala.

  9. AMS 14C and OSL/IRSL dating of the Dunaszekcső loess sequence (Hungary): chronology for 20 to 150 ka and implications for establishing reliable age-depth models for the last 40 ka

    NASA Astrophysics Data System (ADS)

    Újvári, Gábor; Molnár, Mihály; Novothny, Ágnes; Páll-Gergely, Barna; Kovács, János; Várhegyi, András

    2014-12-01

    As revealed by 18 AMS radiocarbon and 24 OSL/IRSL ages the Dunaszekcső loess-paleosol sequence is an excellent terrestrial record of paleoenvironmental change in the Carpathian Basin for the last 130 ka, with significant soil forming episodes during the Eemian interglacial (130-115 ka, MIS 5e) and in some subsequent MIS 5 stages, and distinct periods of loess accumulations during the MIS 4 and MIS 2. Charcoals from the sequence made it possible to test the accuracy of 14C ages from mollusc shells. This approach revealed that 14C ages from some gastropods having small shells (<10 mm) (Succinella oblonga, Vitrea crystallina) are statistically indistinguishable from the ages of charcoals, while others (Clausiliidae sp., Chondrula tridens) show age anomalies up to 600-800 years. OSL and pIRIR@290 ages are found to be consistently older, while post-IR OSL ages are younger than the 14C ages from charcoals and molluscs by some thousands of years, except for pIRIR@225 ages that match the radiocarbon ages quite well. OSL and IRSL ages have scatters up to 7-10 thousand years within 40 ka, while charcoals and small molluscs yield consistent ages with relatively low variability. Beyond the observation that some small molluscs seem to yield reliable 14C ages, calibrated 2σ age ranges of the radiocarbon data (ca 500-800 years for 20 to 30 ka) are an order of magnitude narrower than those of the OSL/IRSL methods (1800-4000 years for 25 to 35 ka). Thus, for establishing chronologies within 40 ka, which are both accurate and precise enough to address issues like synchroneity of millennial-scale paleoenvironmental events across regions (e.g. North Atlantic and Europe), AMS radiocarbon dating of shells of specific loess molluscs and charcoals may probably be a powerful chronological tool. However, additional work is definitely required involving 14C and OSL/IRSL dates from other loess sequences to further test the performance of these two supposedly robust chronometers.

  10. Co-Occurring Psychiatric Disorders in Preschool and Elementary School-Aged Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Salazar, Fernando; Baird, Gillian; Chandler, Susie; Tseng, Evelin; O'sullivan, Tony; Howlin, Patricia; Pickles, Andrew; Simonoff, Emily

    2015-01-01

    We employed a clinical sample of young children with ASD, with and without intellectual disability, to determine the rate and type of psychiatric disorders and possible association with risk factors. We assessed 101 children (57 males, 44 females) aged 4.5-9.8 years. 90.5% of the sample met the criteria. Most common diagnoses were: generalized…

  11. Autism Spectrum Disorder in Children and Adolescents with Fragile X Syndrome: Within-Syndrome Differences and Age-Related Changes

    ERIC Educational Resources Information Center

    McDuffie, Andrea; Abbeduto, Leonard; Lewis, Pamela; Kover, Sara; Kim, Jee-Seon; Weber, Ann; Brown, W. Ted

    2010-01-01

    The Autism Diagnostic Interview-Revised (ADI-R) was used to examine diagnostic profiles and age-related changes in autism symptoms for a group of verbal children and adolescents who had fragile X syndrome, with and without autism. After controlling for nonverbal IQ, we found statistically significant between-group differences for lifetime and…

  12. Mothers' Parenting Behaviors in Families of School-Aged Children with Autism Spectrum Disorder: An Observational and Questionnaire Study

    ERIC Educational Resources Information Center

    Boonen, Hannah; van Esch, Lotte; Lambrechts, Greet; Maljaars, Jarymke; Zink, Inge; Van Leeuwen, Karla; Noens, Ilse

    2015-01-01

    Although parents of children with ASD face specific challenges in parenting, only a few studies have empirically investigated parenting behaviors among these parents. The current study examined differences in parenting behaviors between mothers of school-aged children with ASD (n = 30) and mothers of typically developing children (n = 39), using…

  13. Age-Related Differences in Response to Music-Evoked Emotion among Children and Adolescents with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Stephenson, K. G.; Quintin, E. M.; South, M.

    2016-01-01

    While research regarding emotion recognition in ASD has focused primarily on social cues, musical stimuli also elicit strong emotional responses. This study extends and expands the few previous studies of response to music in ASD, measuring both psychophysiological and behavioral responses in younger children (ages 8-11) as well as older…

  14. Systemic, Integrated, and Sustainable Family Engagement across the Early Age Spectrum in San Mateo and Santa Clara Counties. Issue Brief

    ERIC Educational Resources Information Center

    Fehrer, Kendra

    2014-01-01

    A growing body of evidence indicates the critical importance of appropriate supports for children and their families at early ages, as well as the potential for targeted interventions to make meaningful contributions to children's development. Family involvement in the early years of a child's learning and development can serve as a protective…

  15. The Effects of Age and Treatment Intensity on Behavioral Intervention Outcomes for Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Granpeesheh, Doreen; Dixon, Dennis R.; Tarbox, Jonathan; Kaplan, Andrew M.; Wilke, Arthur E.

    2009-01-01

    Early intensive behavioral intervention (EIBI) has been shown to effectively remediate some cases of autism. However, few studies have evaluated the importance of various factors, such as the effect of treatment intensity on treatment outcomes, and how these outcomes vary by age. The objective of this study was to evaluate the relationship of…

  16. Dating slate belts using 40Ar/39Ar geochronology and zircon ages from crosscutting plutons: A case study from east-central Maine, USA

    NASA Astrophysics Data System (ADS)

    Ghanem, Hind; Kunk, Michael J.; Ludman, Allan; Bish, David L.; Wintsch, Robert P.

    2016-12-01

    We report the ages of cleavage development in a normally intractable lower greenschist facies slate belt, the Central Maine-Aroostook-Matapedia belt in east-central Maine. We have attacked this problem by identifying the minimum ages of muscovite in a regional Acadian cleavage (S1) and in a local ductile fault zone cleavage (S2) using 40Ar/39Ar geochronology and the ages of crosscutting plutons. Our success stems from the regional low-grade metamorphism of the rocks in which each crystallization event preserves a40Ar/39Ar crystallization age and not a cooling age. Evidence for recrystallization via a pressure solution mechanism comes from truncations of detrital, authigenic, and in some rocks S1 muscovite and chlorite grains by new cleavage-forming muscovite and chlorite grains. Low-blank furnace age spectra from meta-arkosic and slaty rocks climb from moderate temperature Devonian age-steps dominated by cleavage-forming muscovite to Ordovician age-steps dominated by a detrital muscovite component. S1- and S2-cleaved rocks were hornfelsed by granitoids of ∼407 and 377 Ma, respectively. The combination of these minimum ages with the maximum metamorphic crystallization ages establishes narrow constraints on the timing of these two cleavage-forming events, ∼410 Ma (S1) and ∼380 Ma (S2). These two events coincide in time with a change in the plate convergence kinematics from the arrival of the Avalon terrane (Acadian orogeny), to a right-lateral transpression arrival of the Meguma terrane in the Neoacadian orogeny.

  17. The fears, phobias and anxieties of children with autism spectrum disorders and Down syndrome: comparisons with developmentally and chronologically age matched children.

    PubMed

    Evans, David W; Canavera, Kristin; Kleinpeter, F Lee; Maccubbin, Elise; Taga, Ken

    2005-01-01

    This study compared the fears and behavior problems of 25 children with an autism spectrum disorder (ASD), 43 children with Down syndrome (DS), 45 mental age (MA) matched children, and 37 chronologically age (CA) matched children. Children's fears, phobias, anxieties and behavioral problems were assessed using parent reports. Significant differences emerged across the diagnostic groups on a variety of fears. Children with ASD were reported to have more situation phobias and medical fears, but fewer fears of harm/injury compared to all other groups. The groups also differed in terms of the pattern of correlations between fears, phobias, anxieties and behavior problems. For children with ASD, fears, phobias and anxieties were closely related to problem behaviors, whereas fears, phobias, and anxieties were less related to behavioral symptoms for the other groups of subjects. Such findings suggest that children with ASD exhibit a distinct profile of fear and anxiety compared to other mental age and chronologically age-matched children, and these fears are related to the symptoms associated with ASD.

  18. Radiocarbon Dating, Memories, and Hopes

    DOE R&D Accomplishments Database

    Libby, W. F.

    1972-10-01

    The history of radiocarbon dating from 1939 to the present is reviewed. The basic principles of radiocarbon dating are that cosmic rays make living things radioactive with {sup 14}C to a certain level fixed by the environment and that at death the intake of food stops so no replenishment of the {sup 14}C steadily lost by the immutable decay occurs. Therefore measurement of the degree of decay gives the time lapse since death, i.e., the radiocarbon age. The equipment developed and experiments performed to measure the specific activity of specimens to be dated are described. The results obtained by world-wide experimenters are discussed. These showed that on simultaneity radiocarbon dating is apparently reliable but that absolute dates may be incorrect by as much as 600 to 700 y. The value of radiocarbon dating to archaeologists, geologists, climatologists, and historians is stressed. (LCL)

  19. Age dating and flow path evaluation of groundwater by SF6 and microbe in the foot of Mt. Fuji, central Japan

    NASA Astrophysics Data System (ADS)

    Yamamoto, Chisato; Tsujimura, Maki; Kato, Kenji; Nagaosa, Kazuyo; Sakakibara, Koichi; Umei, Yohei; Ohara, Kazuma

    2016-04-01

    A variety of industries are developed at the foot of volcanic mountains in Japan and the groundwater is major source for industrial activity in those regions. The age of groundwater has been estimated to be from 10 to 30 years in Mt. Fuji regions by using 36Cl and 3H. However, the age has not been evaluated using SF6 with higher time resolution in these regions. Also, the total number of prokaryotes shows a specific value in each spring water, suggesting different path and age of the groundwater. Therefore, we aim to estimate residence time and the groundwater flow in three dimensions using the multi-tracers approach; CFCs, SF6, the total number of prokaryotes, the stable isotopes of oxygen-18, deuterium. We collected totally 25 spring water samples in Mt. Fuji and analyzed concentration of inorganic ions, the stable isotopes of oxygen-18, deuterium, CFCs, SF6. The apparent age of the spring water was estimated to be ranging from 4 to 19 years at the foot of Mt. Fuji. These results are reasonable as considering the existed age data by36Cl (Tosaki, 2008) in this region. The spring water with younger age tends to show higher total number of prokaryotes, suggesting that the groundwater flows dominantly through the shallow and young lava with the higher total number of prokaryotes, leads to younger age. Focusing on a specific spring water, the seasonal change of SF6 and total number of prokaryotes were monitored. The spring water showed a younger age and higher total number of prokaryotes during the high water flow season, whereas it showed an older age and lower total number of prokaryotes. Therefore, the total number of prokaryotes shows a good negative correlation with the residence time of the spring/ groundwater in space and time. This shows a possibility that the total number of prokaryotes could be a useful tracer of groundwater for time and space in the three dimensions information.

  20. 40Ar/39Ar dating of ignimbrite from Inner Mongolia, northeastern China, indicates a post-Middle Jurassic age for the overlying Daohugou Bed

    NASA Astrophysics Data System (ADS)

    He, H. Y.; Wang, X. L.; Zhou, Z. H.; Zhu, R. X.; Jin, F.; Wang, F.; Ding, X.; Boven, A.

    2004-10-01

    The 40Ar/39Ar step heating analyses of K-feldspar derived from the ignimbrite in Inner Mongolia, China indicates that they were formed at 159.8 +/- 0.8 Ma, which provides a maximum age for the overlying fossil-bearing lacustrine deposits (Daohugou Bed). This result favors a post-Middle Jurassic (Late Jurassic or younger), rather than the Middle Jurassic age for the Daohugou Bed. Such a result is generally consistent with vertebrate biostratigraphic evidence, providing a maximum known age for the first appearance of several major animal groups such as Cryptobranchidae of Urodela (salamanders) and Maniraptora (birds and their closest dinosaurian relatives).

  1. Optical and thermoluminescence dating of Middle Stone Age and Kintampo bearing sediments at Birimi, a multi-component archaeological site in Ghana

    NASA Astrophysics Data System (ADS)

    Quickert, Nicole A.; Godfrey-Smith, Dorothy I.; Casey, Joanna L.

    2003-05-01

    We report the first luminescence ages for the archeological and geological sediments forming the substrate of the Birimi archaeological site in the Northern Region of Ghana. The site's significance rests on the fact that it contains a rich collection of artifact assemblages representative of three distinct cultures, and that, on the basis of artifact typology, the earliest assemblage is diagnostic of the Middle Stone Age (MSA) . In situ occurrences of MSA artifacts are found at over 1 m below today's surface. They are overlain by a ceramic-rich complex of a sedentary or semi-sendentary Later Stone Age culture known as the Kintampo. The western half of the site is dominated by the industrial remains of Iron Age smelting activity. Elemental, mineralogical, and sedimentological analysis of the cultural and sub-cultural sedimentary horizons at the site revealed at least three distinct lithostratigraphic units. The quartz sediments are derived from the sandstone of the Gambaga escarpment, mass wasted and accreted fluvially at a rate of 3.2 cm/ka, forming a wide terrace at Birimi. Silts and finer fractions derive from windblown dust, likely from White Volta River and granitic sources to the north. Soil forming processes and wide fluctuations in moisture have progressively reduced the sediments at depth to the resistant quartz and kaolinite, with rich iron oxide coatings, and created two ironstone horizons composed of goethite-cemented quartz nodules. Multiple aliquot green-light stimulated optical ages for 125-150 μm quartz grains yielded ages of 23.6±2.9 and 40.8±11.8 ka for the MSA-bearing sediments, and 58.4±15.3 ka for the base of the terrace. Radiocarbon ages on charcoal from Kintampo-bearing units are 3.36-3.83 ka cal BP, and are supported by thermoluminescence (TL) ages on pottery sherds and burnt house daub fragments of this cultural complex. A 0.4 ka age on sediment from the site's surface confirms that the quartz zeroes well when exposed to natural light

  2. Assistive technology as a predictor of general or alternate assessment among elementary-aged students with autism spectrum disorders.

    PubMed

    Barnard-Brak, Lucy; Thompson, Samuel; Wei, Tianlan; Richman, David

    2014-01-01

    The No Child Left Behind Act of 2001 specifically mandates that all students participate in the general assessment process or some form of alternate assessment as a measure of school accountability for student academic progress. Although levels of communication difficulties, intellectual impairment, and specific diagnoses such as autism spectrum disorders (ASDs) are correlated with increased probability of participating in alternate assessment methods, very little empirical research has focused on identifying predictors for students' assessment modality. Archival data from the Special Education Elementary Longitudinal Study (SEELS; 2005) were used to examine variables that predict whether elementary school students with ASD participated in the general or alternate assessment. Results indicated that receptive and expressive communication abilities appear to influence participation in the general vs. alternate assessment in tandem with access to assistive technology. Students with ASDs were approximately 2.71 times more likely to participate in the general assessment when they had access to assistive technology. Next, we performed a second, follow-up analysis for only ASD students with communication problems. The odds ratio value increased to 14.9 indicating that ASD students with communication problems that had access to assistive technology were almost 15 times more likely to participate in the general assessment than students with communication problems without access to assistive technology.

  3. The age of the Keystone thrust: laser-fusion 40Ar/39Ar dating of foreland basin deposits, southern Spring Mountains, Nevada

    USGS Publications Warehouse

    Fleck, R.J.; Carr, M.D.

    1990-01-01

    Nonmarine sedimentary and volcaniclastic foreland-basin deposits in the Spring Mountains are cut by the Contact and Keystone thrusts. These synorogenic deposits, informally designated the Lavinia Wash sequence by Carr (1980), previously were assigned a Late Jurassic to Early Cretaceous(?) age. New 40Ar.39Ar laser-fusion and incremental-heating studies of a tuff bed in the Lavinia Wash sequence support a best estimate age of 99.0 ?? 0.4 Ma, indicating that the Lavinia Wash sequence is actually late Early Cretaceous in age and establishing a maximum age for final emplacement of the Contact and Keystone thrust plates consistent with the remainder of the Mesozoic foreland thrust belt. -from Authors

  4. Aging of marine organic matter during cross-shelf lateral transport in the Benguela upwelling system revealed by compound-specific radiocarbon dating

    NASA Astrophysics Data System (ADS)

    Mollenhauer, Gesine; Inthorn, Maik; Vogt, Thomas; Zabel, Matthias; Sinninghe Damsté, Jaap S.; Eglinton, Timothy I.

    2007-09-01

    Organic matter accumulation and burial on the Namibian shelf and upper slope are spatially heterogeneous and strongly controlled by lateral transport in subsurface nepheloid layers. Much of the material deposited in depo-centers on the slope ultimately derives from the shelf. Supply of organic matter from the shelf involves selective transport of organic matter. We studied these selective transport processes by analyzing the radiocarbon content of co-occurring sediment fractions. Here we present radiocarbon data for total organic carbon as well as three tracers of surface ocean productivity (phytoplankton-derived alkenones, membrane lipids of pelagic crenarchaeota (crenarchaeol), and calcareous microfossils of planktic foraminifera) in core-top and near-surface sediment samples. The samples were collected on the Namibian margin along a shelf-slope transect (85 to 1040 m) at 24°S and from the upper slope depo-center at 25.5°S. In core-top sediments, alkenone ages gradually increased from modern to 3490 radiocarbon years with distance from shore and with water depth. Crenarchaeol, while younger than alkenones, also increased in age with distance offshore. It was concluded that the observed ages were a consequence of cross-shelf transport and associated aging of organic matter. Radiocarbon ages of preserved lipid biomarkers in sediments thus at least partially depend on the relative amount of laterally supplied, pre-aged material present in a sample, highlighting the importance of nepheloid transport for the sedimentation of organic matter over the Namibian margin.

  5. Strategies for Family Facilitation of Play Dates

    ERIC Educational Resources Information Center

    Chambers, Cynthia R.; Horn, Eva M.

    2010-01-01

    Play dates can serve several functions for young children, including children with social difficulties, such as developmental delays, behavioral disorders, autism spectrum disorders, and shyness. Play dates provide children with additional opportunities to be around peers and to practice skills associated with peer play interactions. Play dates…

  6. Lexical Processing in School-Age Children with Autism Spectrum Disorder and Children with Specific Language Impairment: The Role of Semantics

    PubMed Central

    Haebig, Eileen; Kaushanskaya, Margarita; Weismer, Susan Ellis

    2016-01-01

    Children with autism spectrum disorder (ASD) and specific language impairment (SLI) often have immature lexical-semantic knowledge; however, the organization of lexical-semantic knowledge is poorly understood. This study examined lexical processing in school-age children with ASD, SLI, and typical development, who were matched on receptive vocabulary. Children completed a lexical decision task, involving words with high and low semantic network sizes and nonwords. Children also completed nonverbal updating and shifting tasks. Children responded more accurately to words from high than from low semantic networks; however, follow-up analyses identified weaker semantic network effects in the SLI group. Additionally, updating and shifting abilities predicted lexical processing, demonstrating similarity in the mechanisms which underlie semantic processing in children with ASD, SLI, and typical development. PMID:26210517

  7. Lexical Processing in School-Age Children with Autism Spectrum Disorder and Children with Specific Language Impairment: The Role of Semantics.

    PubMed

    Haebig, Eileen; Kaushanskaya, Margarita; Ellis Weismer, Susan

    2015-12-01

    Children with autism spectrum disorder (ASD) and specific language impairment (SLI) often have immature lexical-semantic knowledge; however, the organization of lexical-semantic knowledge is poorly understood. This study examined lexical processing in school-age children with ASD, SLI, and typical development, who were matched on receptive vocabulary. Children completed a lexical decision task, involving words with high and low semantic network sizes and nonwords. Children also completed nonverbal updating and shifting tasks. Children responded more accurately to words from high than from low semantic networks; however, follow-up analyses identified weaker semantic network effects in the SLI group. Additionally, updating and shifting abilities predicted lexical processing, demonstrating similarity in the mechanisms which underlie semantic processing in children with ASD, SLI, and typical development.

  8. Mothers' Parenting Behaviors in Families of School-Aged Children with Autism Spectrum Disorder: An Observational and Questionnaire Study.

    PubMed

    Boonen, Hannah; van Esch, Lotte; Lambrechts, Greet; Maljaars, Jarymke; Zink, Inge; Van Leeuwen, Karla; Noens, Ilse

    2015-11-01

    Although parents of children with ASD face specific challenges in parenting, only a few studies have empirically investigated parenting behaviors among these parents. The current study examined differences in parenting behaviors between mothers of school-aged children with ASD (n = 30) and mothers of typically developing children (n = 39), using both an observational measure and a self-report questionnaire. Results indicated that mothers of children with ASD obtained significantly lower scores on Sensitivity and Provision of structure as measured during the observation. They reported significantly higher scores on Material rewarding and Adapting the environment on the questionnaire. When controlling for parenting stress, the group differences on Sensitivity and Material rewarding did not remain significant.

  9. New Sakmarian ages for the Rio Bonito formation (Paraná Basin, southern Brazil) based on LA-ICP-MS U-Pb radiometric dating of zircons crystals

    NASA Astrophysics Data System (ADS)

    Cagliari, Joice; Lavina, Ernesto Luiz Correa; Philipp, Ruy Paulo; Tognoli, Francisco Manoel Wohnrath; Basei, Miguel Angelo Stipp; Faccini, Ubiratan Ferrucio

    2014-12-01

    Two ash fall beds (tonstein) sampled from the post-glacial Permian deposits of the Paraná Basin have provided new U-Pb radiometric age constraints for this stratigraphic interval. The zircon grains were recovered from tonstein layers interbedded with fine-grained and carbonaceous lithologies in the middle portion of the Rio Bonito Formation. In both samples, the dominant population is interpreted as generated by explosive volcanism, as having formed immediately before the eruption. Based on 238U/206Pb, the selected zircon grains from the dominant population have weighted mean ages of 290.6 ± 2.8 Ma and 281.7 ± 3.2 Ma, corresponding to the Sakmarian and Kungurian ages in the Cisuralian epoch, respectively. These ages constrain the time of the deposition of the tonstein horizons and have important stratigraphic implications for the Late Paleozoic evolution of both the Paraná Basin and the southwestern region of Gondwana. The results presented here and the radiometric data already published suggest that deposition of the post-glacial coal-bearing deposits of the Rio Bonito Formation was probably initiated before the Early Permian. Thus, we infer that the climate had already ameliorated by this period in order to allow for the formation and accumulation of peat in this region of Gondwana.

  10. Integrated J- and H-band spectra of globular clusters in the LMC: implications for stellar population models and galaxy age dating

    NASA Astrophysics Data System (ADS)

    Lyubenova, M.; Kuntschner, H.; Rejkuba, M.; Silva, D. R.; Kissler-Patig, M.; Tacconi-Garman, L. E.

    2012-07-01

    Context. The rest-frame near-IR spectra of intermediate age (1-2 Gyr) stellar populations are dominated by carbon based absorption features offering a wealth of information. Yet, spectral libraries that include the near-IR wavelength range do not sample a sufficiently broad range of ages and metallicities to allow for accurate calibration of stellar population models and thus the interpretation of the observations. Aims: In this paper we investigate the integrated J- and H-band spectra of six intermediate age and old globular clusters in the Large Magellanic Cloud (LMC). Methods: The observations for six clusters were obtained with the SINFONI integral field spectrograph at the ESO VLT Yepun telescope, covering the J (1.09-1.41 μm) and H-band (1.43-1.86 μm) spectral range. The spectral resolution is 6.7 Å in J and 6.6 Å in H-band (FWHM). The observations were made in natural seeing, covering the central 24″ × 24″ of each cluster and in addition sampling the brightest eight red giant branch and asymptotic giant branch (AGB) star candidates within the clusters' tidal radii. Targeted clusters cover the ages of ~1.3 Gyr (NGC 1806, NGC 2162), 2 Gyr (NGC 2173) and ~13 Gyr (NGC 1754, NGC 2005, NGC 2019). Results.H-band C2 and K-band 12CO (2-0) feature strengths for the LMC globular clusters are compared to the models of Maraston (2005). C2 is reasonably well reproduced by the models at all ages, while 12CO (2-0) shows good agreement for older (age ≥ 2 Gyr) populations, but the younger (1.3 Gyr) globular clusters do not follow the models. We argue that this is due to the fact that the empirical calibration of the models relies on only a few Milky Way carbon star spectra, which show different 12CO (2-0) index strengths than the LMC stars. The C2 absorption feature strength correlates strongly with age. It is present essentially only in populations that have 1-2 Gyr old stars, while its value is consistent with zero for older populations. The distinct spectral

  11. Radiocarbon dating of terrestrial carbonates

    USGS Publications Warehouse

    Pigati, Jeffrey S.; Rink, W. Jack; Thompson, Jeroen

    2014-01-01

    Terrestrial carbonates encompass a wide range of materials that potentially could be used for radiocarbon (14C) dating. Biogenic carbonates, including shells and tests of terrestrial and aquatic gastropods, bivalves, ostracodes, and foraminifera, are preserved in a variety of late Quaternary deposits and may be suitable for 14C dating. Primary calcareous deposits (marls, tufa, speleothems) and secondary carbonates (rhizoliths, fracture fill, soil carbonate) may also be targeted for dating when conditions are favorable. This chapter discusses issues that are commonly encountered in 14C dating of terrestrial carbonates, including isotopic disequilibrium and open-system behavior, as well as methods used to determine the reliability of ages derived from these materials. Recent methodological advancements that may improve the accuracy and precision of 14C ages of terrestrial carbonates are also highlighted.

  12. Dating sediments using luminescence signals

    SciTech Connect

    Wintle, A. )

    1993-05-01

    Before siting a nuclear power station or a nuclear waste repository, it is necessary to establish that the area has been free of earthquake activity for a sufficient period of time. Evidence of past earthquake activity is often provided by faults in surface sediments. Age limits for fault formation can be set by obtaining the depositional ages of the sediment unit in which the fault was formed and the overlying sediment. A useful technique would be one that dating could be applied to the mineral grains that make up the sediments and that would give the time that has passed since the grains were blown or washed into position. Luminescence dating techniques, of which the most well known is thermo-luminescence (TL), provide such information. This approach has been successful in dating movement on the Wasatch Fault in Utah. A combination of TL and radiocarbon dates indicated that three faulting events had occurred within the past 5000 years. 2 refs., 1 fig.

  13. Education and health among U.S. working-age adults: a detailed portrait across the full educational attainment spectrum.

    PubMed

    Zajacova, Anna; Hummer, Robert A; Rogers, Richard G

    2012-01-01

    This article presents detailed estimates of relative and absolute health inequalities among U.S. working-age adults by educational attainment, including six postsecondary schooling levels. We also estimate the impact of several sets of mediating variables on the education-health gradient. Data from the 1997-2009 National Health Interview Survey (N = 178,103) show remarkable health differentials. For example, high school graduates have 3.5 times the odds of reporting "worse" health than do adults with professional or doctoral degrees. The probability of fair or poor health in mid-adulthood is less than 5 percent for adults with the highest levels of education but over 20 percent for adults without a high school diploma. The probability of reporting excellent health in the mid-forties is below 25 percent among high school graduates but over 50 percent for those adults who have professional degrees. These health differences characterize all the demographic subgroups examined in this study. Our results show that economic indicators and health behaviors explain about 40 percent of the education-health relationship. In the United States, adults with the highest educational degrees enjoy a wide array of benefits, including much more favorable self-rated health, compared to their less-educated counterparts.

  14. Autism Spectrum Disorder (ASD): Related Topics

    MedlinePlus

    ... Facebook Tweet Share Compartir Q: Do vaccines cause autism spectrum disorder (ASD)? A: Many studies that have ... whether there is a relationship between vaccines and autism spectrum disorder (ASD). To date, the studies continue ...

  15. Radioactive dating of the elements

    NASA Technical Reports Server (NTRS)

    Cowan, John J.; Thielemann, Friedrich-Karl; Truran, James W.

    1991-01-01

    The extent to which an accurate determination of the age of the Galaxy, and thus a lower bound on the age of the universe, can be obtained from radioactive dating is discussed. Emphasis is given to the use of the long-lived radioactive nuclei Re-187, Th-232, U-238, and U-235. The nature of the production sites of these and other potential Galactic chronometers is examined along with their production ratios. Age determinations from models of nucleocosmochronology are reviewed and compared with age determination from stellar sources and age constraints form cosmological considerations.

  16. The impact of minimum legal drinking age laws on alcohol consumption, smoking, and marijuana use: evidence from a regression discontinuity design using exact date of birth.

    PubMed

    Yörük, Barış K; Yörük, Ceren Ertan

    2011-07-01

    This paper uses a regression discontinuity design to estimate the impact of the minimum legal drinking age laws on alcohol consumption, smoking, and marijuana use among young adults. Using data from the National Longitudinal Survey of Youth (1997 Cohort), we find that granting legal access to alcohol at age 21 leads to an increase in several measures of alcohol consumption, including an up to a 13 percentage point increase in the probability of drinking. Furthermore, this effect is robust under several different parametric and non-parametric models. We also find some evidence that the discrete jump in alcohol consumption at age 21 has negative spillover effects on marijuana use but does not affect the smoking habits of young adults. Our results indicate that although the change in alcohol consumption habits of young adults following their 21st birthday is less severe than previously known, policies that are designed to reduce drinking among young adults may have desirable impacts and can create public health benefits.

  17. Severe multisensory speech integration deficits in high-functioning school-aged children with Autism Spectrum Disorder (ASD) and their resolution during early adolescence.

    PubMed

    Foxe, John J; Molholm, Sophie; Del Bene, Victor A; Frey, Hans-Peter; Russo, Natalie N; Blanco, Daniella; Saint-Amour, Dave; Ross, Lars A

    2015-02-01

    Under noisy listening conditions, visualizing a speaker's articulations substantially improves speech intelligibility. This multisensory speech integration ability is crucial to effective communication, and the appropriate development of this capacity greatly impacts a child's ability to successfully navigate educational and social settings. Research shows that multisensory integration abilities continue developing late into childhood. The primary aim here was to track the development of these abilities in children with autism, since multisensory deficits are increasingly recognized as a component of the autism spectrum disorder (ASD) phenotype. The abilities of high-functioning ASD children (n = 84) to integrate seen and heard speech were assessed cross-sectionally, while environmental noise levels were systematically manipulated, comparing them with age-matched neurotypical children (n = 142). Severe integration deficits were uncovered in ASD, which were increasingly pronounced as background noise increased. These deficits were evident in school-aged ASD children (5-12 year olds), but were fully ameliorated in ASD children entering adolescence (13-15 year olds). The severity of multisensory deficits uncovered has important implications for educators and clinicians working in ASD. We consider the observation that the multisensory speech system recovers substantially in adolescence as an indication that it is likely amenable to intervention during earlier childhood, with potentially profound implications for the development of social communication abilities in ASD children.

  18. Age at diagnosis of autism spectrum disorders: is there an association with socioeconomic status and family self-education about autism?

    PubMed Central

    Hrdlicka, Michal; Vacova, Maria; Oslejskova, Hana; Gondzova, Veronika; Vadlejchova, Iveta; Kocourkova, Jana; Koutek, Jiri; Dudova, Iva

    2016-01-01

    Background The marked increase in autism spectrum disorders (ASD) prevalence has stimulated worldwide interest in exploring broader circumstances of care of autistic children, including the role of socioeconomic status (SES) and family information on autism. Methods Our sample comprised of 160 children who participated in a diagnostic examination focused on autism, and their parents who completed a simple descriptive questionnaire focusing on the family situation as well as family self-education about autism. The diagnosis of ASD was confirmed in 120 children (75% of the sample; 94 boys, 26 girls) with mean age 6.2±2.7 years (median 5.3, range 2.2–17.2 years). In 71 autistic patients (59.2%), a diagnosis of mental retardation was also established. Results The age at diagnosis of ASD correlated negatively with maternal (P=0.014) and paternal (P=0.002) ages at the time of birth of the ASD child as well as with paternal (P=0.002) and maternal (P=0.050) education. The age at diagnosis of ASD did not correlate with family SES. Mothers were significantly more active in seeking information on autism than fathers or both parents equally (80 vs 9 vs 28 cases, respectively; P<0.001). The mean number of information sources on autism was 3.5±1.8 with a range 0–9. The mean number of resources did not differ among the three SES groups (3.50 vs 3.49 vs 4.25, respectively; P=0.704). The mean number of sources did not correlate with the age at diagnosis of ASD. The most often used sources were the Internet (81.7%), followed by psychologists (48.3%), books (46.7%), and child and adolescent psychiatrists (43.3%). Conclusion An earlier diagnosis of ASD is associated with higher parental age at birth and higher parental education but not with family SES or number of family information sources. PMID:27462156

  19. 210Pb dating

    USGS Publications Warehouse

    Swarzenski, Peter W.

    2014-01-01

    Roughly fifty years ago, a small group of scientists from Belgium and the United States, trying to better constrain ice sheet accumulation rates, attempted to apply what was then know about environmental lead as a potential geochronometer. Thus Goldberg (1963) developed the first principles of the 210Pb dating method, which was soon followed by a paper by Crozaz et al. (1964), who examined accumulation history of Antarctic snow using 210Pb. Shortly thereafter, Koide et al. (1972, 1973) adapted this technique to unravel sediment deposition and accumulation records in deep-sea environments. Serendipitously, they chose to work in a deep basin off California, where an independent and robust age model had already been developed. Krishanswami et al. (1971) extended the use of this technique to lacustrine deposits to reconstruct depositional histories of lake sediment, and maybe more importantly, contaminant inputs and burial. Thus, the powerful tool for dating recent (up to about one century old) sediment deposits was established and soon widely adopted. Today almost all oceanographic or limnologic studies that address recent depositional reconstructions employ 210Pb as one of several possible geochronometers (Andrews et al., 2009; Gale, 2009; Baskaran, 2011; Persson and Helms, 2011). This paper presents a short overview of the principles of 210Pb dating and provides a few examples that illustrate the utility of this tracer in contrasting depositional systems. Potential caveats and uncertainties (Appleby et al., 1986; Binford, 1990; Binford et al., 1993; Smith, 2001; Hancock et al., 2002) inherent to the use and interpretation of 210Pb-derived age-models are also introduced. Recommendations as to best practices for most reliable uses and reporting are presented in the summary.

  20. Declarative verbal memory impairments in middle-aged women who are caregivers of offspring with autism spectrum disorders: The role of negative affect and testosterone.

    PubMed

    Romero-Martínez, A; González-Bono, E; Salvador, A; Moya-Albiol, L

    2016-01-01

    Caring for offspring diagnosed with a chronic psychological disorder such as autism spectrum disorder (ASD) is used in research as a model of chronic stress. This chronic stress has been reported to have deleterious effects on caregivers' cognition, particularly in verbal declarative memory. Moreover, such cognitive decline may be mediated by testosterone (T) levels and negative affect, understood as depressive mood together with high anxiety and anger. This study aimed to compare declarative memory function in middle-aged women who were caregivers for individuals with ASD (n = 24; mean age = 45) and female controls (n = 22; mean age = 45), using a standardised memory test (Rey's Auditory Verbal Learning Test). It also sought to examine the role of care recipient characteristics, negative mood and T levels in memory impairments. ASD caregivers were highly sensitive to proactive interference and verbal forgetting. In addition, they had higher negative affect and T levels, both of which have been associated with poorer verbal memory performance. Moreover, the number of years of caregiving affected memory performance and negative affect, especially, in terms of anger feelings. On the other hand, T levels in caregivers had a curvilinear relationship with verbal memory performance; that is, increases in T were associated with improvements in verbal memory performance up to a certain point, but subsequently, memory performance decreased with increasing T. Chronic stress may produce disturbances in mood and hormonal levels, which in turn might increase the likelihood of developing declarative memory impairments although caregivers do not show a generalised decline in memory. These findings should be taken into account for understanding the impact of cognitive impairments on the ability to provide optimal caregiving.

  1. A comparison of spectral quality in magnetic resonance spectroscopy data acquired with and without a novel EPI-navigated PRESS sequence in school-aged children with fetal alcohol spectrum disorders.

    PubMed

    Hess, Aaron T; Jacobson, Sandra W; Jacobson, Joseph L; Molteno, Christopher D; van der Kouwe, André J W; Meintjes, Ernesta M

    2014-06-01

    Single voxel spectroscopy (SVS) can generate useful information regarding metabolite concentrations provided that the MR signal can be averaged over several minutes during which the subject remains stationary. This requirement can be particularly challenging for children who cannot otherwise be scanned without sedation. To address this problem we developed an EPI volume navigated (vNav) SVS PRESS sequence, which applies real-time head pose (location and orientation), frequency, and first-order B0 shim adjustments. A water-independent preprocessing algorithm removes residual frequency and phase shifts resulting from within-TR movements. We compare results and performance of the standard and vNav PRESS sequences in a sample of 9- to 10-year-olds from a South African cohort of children with fetal alcohol spectrum disorders (FASD) and healthy controls. Magnetic resonance spectroscopy (MRS) data in the deep cerebellar nuclei were initially acquired with the standard PRESS sequence. The children were re-scanned 1 year later with the vNav PRESS sequence. Good quality data were acquired in 73% using the vNav PRESS sequence, compared to only 50% for the standard PRESS sequence. Additionally, tighter linewidths and smaller variances in the measured concentrations were observed. These findings confirm previous reports demonstrating the efficacy of our innovative vNav sequence with healthy volunteers and young children with HIV and expand its application to a school-aged population with FASD-disorders often associated with attention problems and hyperactivity. This study provides the most direct evidence to date regarding degree to which these new methods can improve data quality in research studies employing MRS.

  2. 77 FR 25145 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-27

    ... National Telecommunications and Information Administration Commerce Spectrum Management Advisory Committee.... ACTION: Notice of open meeting. SUMMARY: This notice announces a public meeting of the Commerce Spectrum... Commerce for Communications and Information on spectrum management policy matters. DATES: The meeting...

  3. 75 FR 75968 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-07

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  4. 75 FR 64699 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-20

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  5. 77 FR 35941 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-15

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  6. 78 FR 57370 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-18

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  7. 76 FR 38638 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-01

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    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-12

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    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-15

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    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-26

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  11. 76 FR 23796 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-28

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  12. 76 FR 27636 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-12

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  13. 77 FR 69597 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-20

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  14. 77 FR 5494 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-03

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  15. 78 FR 49260 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-13

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  16. 75 FR 72792 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-26

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  17. Gender Effects on Challenging Behaviors in Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Kozlowski, Alison M.; Matson, Johnny L.; Rieske, Robert D.

    2012-01-01

    Challenging behaviors are extremely prevalent within the autism spectrum disorder (ASD) population. To date, numerous factors affecting the rates of challenging behaviors within the ASD population have been examined including age, gender, ethnicity, and intellectual functioning. Controversy has arisen in regard to the effect of gender on…

  18. A Comprehensive Inclusion Program for Kindergarten Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Sainato, Diane M.; Morrison, Rebecca S.; Jung, Sunhwa; Axe, Judah; Nixon, Patricia A.

    2015-01-01

    To date, reports of empirically validated comprehensive intervention programs for children with autism spectrum disorder (ASD) have been limited to preschool-age children. We examined the effects of a model inclusive kindergarten program for children with ASD. Forty-one children received instruction in an inclusive kindergarten program with their…

  19. Using postnatal age to determine test dates leads to misinterpretations when treatments alter gestation length: results from a collaborative behavioral teratology study in Japan.

    PubMed

    Tachibana, T; Narita, H; Ogawa, T; Tanimura, T

    1998-01-01

    A collaborative study was conducted by researchers from 18 laboratories that participated in the Behavioral Teratology Meeting in Japan. Pregnant Sprague-Dawley rats from four breeders received subcutaneous injections of nicotine (6 mg/kg body weight) from day 7 to day 20 of gestation. Results of preweaning tests were closely related to length of gestation, and prolonged gestation was seen in the nicotine group. The effects of nicotine were compared with and without the adjustment of the mean difference in gestational lengths. Without the adjustment (i.e., by employing assessment in terms of postnatal day) several perplexing results were obtained, indicating that the nicotine group developed more quickly than the control group on several preweaning tests. By employing the adjustment, these perplexing results disappeared, indicating that the nicotine group developed more slowly than the control group. The merit of employing gestational day (or postcoital age) as an alternative index is emphasized.

  20. Identifying sources of dissolved organic carbon in agriculturally dominated rivers using radiocarbon age dating: Sacramento-San Joaquin River Basin, California

    USGS Publications Warehouse

    Sickman, James O.; DiGiorgio, Carol L.; Davisson, M. Lee; Lucero, Delores M.; Bergamaschi, Brian A.

    2010-01-01

    We used radiocarbon measurements of dissolved organic carbon (DOC) to resolve sources of riverine carbon within agriculturally dominated landscapes in California. During 2003 and 2004, average Δ14C for DOC was −254‰ in agricultural drains in the Sacramento–San Joaquin Delta, −218‰ in the San Joaquin River, −175‰ in the California State Water Project and −152‰ in the Sacramento River. The age of bulk DOC transiting the rivers of California’s Central Valley is the oldest reported for large rivers and suggests wide-spread loss of soil organic matter caused by agriculture and urbanization. Using DAX 8 adsorbent, we isolated and measured 14C concentrations in hydrophobic acid fractions (HPOA); river samples showed evidence of bomb-pulse carbon with average Δ14C of 91 and 76‰ for the San Joaquin and Sacramento Rivers, respectively, with older HPOA, −204‰, observed in agricultural drains. An operationally defined non-HPOA fraction of DOC was observed in the San Joaquin River with seasonally computed Δ14C values of between −275 and −687‰; the source of this aged material was hypothesized to be physically protected organic-matter in high clay-content soils and agrochemicals (i.e., radiocarbon-dead material) applied to farmlands. Mixing models suggest that the Sacramento River contributes about 50% of the DOC load in the California State Water Project, and agricultural drains contribute approximately one-third of the load. In contrast to studies showing stabilization of soil carbon pools within one or two decades following land conversion, sustained loss of soil organic matter, occurring many decades after the initial agricultural-land conversion, was observed in California’s Central Valley.

  1. Dating volcanic ash by use of thermoluminescence

    SciTech Connect

    Berger, G.W. )

    1992-01-01

    The fine-silt-sized (4-11 {mu}m) grains of glass separated from four samples of independently dated, 8 to 400 ka, tephra beds provide accurate thermoluminescence (TL) ages. This demonstration of reliable TL dating of volcanic glass provides a new tephrochronometer for deposits spanning the Holocene to middle Pleistocene age range.

  2. New zircon ages on the Cambrian-Ordovician volcanism of the Southern Gemericum basement (Western Carpathians, Slovakia): SHRIMP dating, geochemistry and provenance

    NASA Astrophysics Data System (ADS)

    Vozárová, Anna; Rodionov, Nickolay; Šarinová, Katarína; Presnyakov, Sergey

    2016-11-01

    The Southern Gemericum basement in the Inner Western Carpathians, composed of low-grade volcano-sedimentary rock complexes, constitutes a record of the polyphase Cambrian-Ordovician continental volcanic arc volcanism. These metavolcanic rocks are characterized by the enrichment in K, Rb, Ba, Th and Ce and Sm relative to Ta, Nb, Hf, Zr, Y and Yb that are the characteristic features for volcanic arc magmatites. The new SHRIMP U-Pb zircon data and compilation of previously published and re-evaluated zircon ages, contribute to a new constrain of the timing of the Cambrian-Ordovician volcanism that occurred between 496 and 447 Ma. The following peaks of the volcanic activity of the Southern Gemericum basement have been recognized: (a) mid-late Furongian at 492 Ma; (b) Tremadocian at 481 Ma; (c) Darriwilian at 464 Ma prolonged to 453 Ma within the early Upper Ordovician. The metavolcanic rocks are characterized by a high zircon inheritance, composed of Ediacaran (650-550 Ma), Tonian-Stenian (1.1-0.9 Ma), and, to a lesser extent, Mesoproterozoic (1.3 Ga), Paleoproterozoic (1.9 Ga) and Archaean assemblages (2.6 Ga). Based on the acquired zircon populations, it could be deduced that Cambrian-Ordovician arc crust was generated by a partial melting of Ediacaran basement in the subduction-related setting, into which old crustal fragments were incorporated. The ascertained zircon inheritances with Meso-, Paleoproterozoic and Archaean cores indicate the similarities with the Saharan Metacraton provenance.

  3. Lifetime of an ocean island volcano feeder zone: constraints from U-Pb dating on coexisting zircon and baddeleyite, and 40/39Ar age determinations, Fuerteventura, Canary Islands

    USGS Publications Warehouse

    Allibon, James; Ovtcharova, Maria; Bussy, Francois; Cosca, Michael; Schaltegger, Urs; Bussien, Denise; Lewin, Eric

    2011-01-01

    High-precision isotope dilution - thermal ionization mass spectrometry (ID-TIMS) U-Pb zircon and baddeleyite ages from the PX1 vertically layered mafic intrusion Fuerteventura, Canary Islands, indicate initiation of magma crystallization at 22.10 ± 0.07 Ma. The magmatic activity lasted a minimum of 0.52 Ma. 40Ar/39Ar amphibole dating yielded ages from 21.9 ± 0.6 to 21.8 ± 0.3, identical within errors to the U-Pb ages, despite the expected 1% theoretical bias between 40Ar/39Ar and U-Pb dates. This overlap could result from (i) rapid cooling of the intrusion (i.e., less than the 0.3 to 0.6 Ma 40Ar/39Ar age uncertainties) from closure temperatures (Tc) of zircon (699-988 °C) to amphibole (500-600 °C); (ii) lead loss affecting the youngest zircons; or (iii) excess argon shifting the plateau ages towards older values. The combination of the 40Ar/39Ar and U/Pb datasets implies that the maximum amount of time PX1 intrusion took to cool below amphibole Tc is 0.8 Ma, suggesting PX1 lifetime of 520,000 to 800,000 Ma. Age disparities among coexisting baddeleyite and zircon (22.10 ± 0.07/0.08/0.15 Ma and 21.58 ± 0.15/0.16/0.31 Ma) in a gabbro sample from the pluton margin suggest complex genetic relationships between phases. Baddeleyite is found preserved in plagioclase cores and crystallized early from low silica activity magma. Zircon crystallized later in a higher silica activity environment and is found in secondary scapolite and is found close to calcite veins, in secondary scapolite that recrystallised from plagioclase. close to calcite veins. Oxygen isotope δ18O values of altered plagioclase are high (+7.7), indicating interaction with fluids derived from host-rock carbonatites. The coexistence of baddeleyite and zircon is ascribed to interaction of the PX1 gabbro with CO2-rich carbonatite-derived fluids released during contact metamorphism.

  4. Dating for Older Women: Experiences and Meanings of Dating in Later Life

    PubMed Central

    Watson, Wendy K.; Stelle, Charlie

    2013-01-01

    Research over the last 20 years has provided an increased understanding of intimate relationships in later life; however, dating in later life remains largely unexplored. The purpose of this study was to examine the meanings of dating for women in later life. In this study, dating was examined through semistructured, in-depth interviews with 14 women ages 64 to 77 who had all dated in later life. Themes that emerged from an interpretative phenomenological analysis included multiple meanings of dating in later life, how dating in later life compared to earlier points in life, and dating in the future. PMID:21767089

  5. Results of 40Ar/39Ar dating of phlogopites from kelyphitic rims around garnet grains (Udachnaya-Vostochnaya kimberlite pipe)

    NASA Astrophysics Data System (ADS)

    Yudin, D. S.; Tomilenko, A. A.; Alifirova, T. A.; Travin, A. V.; Murzintsev, N. G.; Pokhilenko, N. P.

    2016-07-01

    40Ar/39Ar dating of phlogopite from kelyphitic rims around garnet grains from the Udachnaya-Vostochnaya kimberlite pipe in the Sakha (Yakutia) Republic (Russia) revealed that when this mineral has contact with a kimberlite melt its age corresponds (within error limits) to that of the formation of the kimberlite pipe, thus indicating that the method may be used for dating kimberlites and related rocks. In mantle xenoliths, kelyphitic phlogopites rimming garnet grains partially lose radiogenic Ar, which results in a complex age spectrum. Rejuvenation of the K/Ar system in them is determined by the thermal impact of the kimberlite melt on captured rocks.

  6. The Autism Symptom Interview, School-Age: A Brief Telephone Interview to Identify Autism Spectrum Disorders in 5-to-12-Year-Old Children

    PubMed Central

    Bishop, Somer L.; Huerta, Marisela; Gotham, Katherine; Havdahl, Karoline Alexandra; Pickles, Andrew; Duncan, Amie; Bal, Vanessa Hus; Croen, Lisa; Lord, Catherine

    2016-01-01

    Lay Abstract Recent advances in multiple areas of autism research, including genetics and epidemiology, have increased the need for large numbers of participants with autism spectrum disorders (ASD). The Autism Symptom Interview (ASI) is a brief phone interview that was designed to facilitate rapid ascertainment of children with ASD for research studies. The ASI is based on questions from the Autism Diagnostic Interview-Revised (ADI-R), a comprehensive, semi-structured parent interview, but the ASI is designed to be administered in approximately 20 minutes by interviewers with minimal training. This study reports on the initial validation of the ASI, School-Age, for children ages 5 to 12 years. Children with previous diagnoses or suspicion of ASD or another neurodevelopmental disorder participated in a comprehensive diagnostic assessment as part of the study and were classified as ASD or non-ASD following the assessment. The ASI scores of children with and without ASD were then compared. For verbal children (defined as using phrases or better on a daily basis), the ASI showed reasonable accuracy in identifying children with ASD (sensitivity=.87), but specificity was low (.62). However, when ASI scores were considered together with scores from the Autism Diagnostic Observation Schedule (ADOS), sensitivity was maintained at .82, and specificity improved to .92. These findings suggest that the ASI school age may serve as a useful tool to more quickly classify children with ASD for research purposes. Scientific Abstract This study reports on the initial validation of the Autism Symptom Interview (ASI), School-Age, a brief (15–20 minute) phone interview derived from questions from the Autism Diagnostic Interview-Revised (ADI-R). The ASI, School-Age was administered by interviewers with minimal training to parents of children ages 5 to 12 who had all been previously identified with (or referred for assessment of) ASD or another neurodevelopmental disorder. Children

  7. Laboratory for Radiokrypton Dating

    NASA Astrophysics Data System (ADS)

    Zappala, J. C.; Jiang, W.; Bailey, K. G.; Lu, Z. T.; Mueller, P.; O'Connor, T. P.

    2015-12-01

    Due to its simple production and transport in the terrestrial environment, 81Kr (half-life = 230,000 yr) is the ideal tracer for old water and ice with mean residence times in the range of 105-106 years, a range beyond the reach of 14C. 81Kr-dating is now available to the earth science community at large thanks to the development of an efficient and selective atom counter based on the Atom Trap Trace Analysis (ATTA) method. ATTA is a laser-based atom counting method where individual neutral atoms of the desired isotope are selectively captured by laser beams, and their fluorescence detected via a CCD camera. ATTA is unique among trace analysis techniques in that it is free of interferences from any other isotopes, isobars, atomic or molecular species. The ATTA instrument at Argonne's Laboratory for Radiokrypton Dating is capable of measuring both 81Kr/Kr and 85Kr/Kr ratios of environmental samples in the range of 10-14-10-10. For 81Kr-dating in the age range of 150 kyr - 1500 kyr, the required sample size is 5 micro-L STP of krypton gas, which can be extracted from approximately 100 kg of water or 40 kg of ice. For 85Kr/Kr analysis, the sample size can be smaller by an order of magnitude. We are continually developing the method towards higher counting efficiency, smaller sample sizes requirements, and higher sample throughput rates. In the past four years, we have performed radiokrypton analysis of over 150 groundwater and ice samples extracted by collaborators from all seven continents. Sample collection and purification was performed by groups including the University of Chicago, the University of Illinois at Chicago, the University of Bern, and the International Atomic Energy Agency. This work is supported by the U.S. DOE, Office of Nuclear Physics, under contract DE-AC02-06CH11357.

  8. Planets Around Low-mass Stars (PALMS). V. Age-dating Low-mass Companions to Members and Interlopers of Young Moving Groups

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.; Shkolnik, Evgenya L.; Liu, Michael C.; Schlieder, Joshua E.; Mann, Andrew W.; Dupuy, Trent J.; Hinkley, Sasha; Crepp, Justin R.; Johnson, John Asher; Howard, Andrew W.; Flagg, Laura; Weinberger, Alycia J.; Aller, Kimberly M.; Allers, Katelyn N.; Best, William M. J.; Kotson, Michael C.; Montet, Benjamin T.; Herczeg, Gregory J.; Baranec, Christoph; Riddle, Reed; Law, Nicholas M.; Nielsen, Eric L.; Wahhaj, Zahed; Biller, Beth A.; Hayward, Thomas L.

    2015-06-01

    We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7-M4.5), most of which have recently been identified as candidate members of nearby young moving groups (YMGs; 8-120 Myr) in the literature. Three of these are new companions identified in our AO imaging survey, and two others are confirmed to be comoving with their host stars for the first time. The inferred masses of the companions (˜10-100 MJup) are highly sensitive to the ages of the primary stars; therefore we critically examine the kinematic and spectroscopic properties of each system to distinguish bona fide YMG members from old field interlopers. The new M7 substellar companion 2MASS J02155892-0929121 C (40-60 MJup) shows clear spectroscopic signs of low gravity and, hence, youth. The primary, possibly a member of the ˜40 Myr Tuc-Hor moving group, is visually resolved into three components, making it a young low-mass quadruple system in a compact (≲100 AU) configuration. In addition, Li i λ6708 absorption in the intermediate-gravity M7.5 companion 2MASS J15594729+4403595 B provides unambiguous evidence that it is young (≲200 Myr) and resides below the hydrogen-burning limit. Three new close-separation (<1″) companions (2MASS J06475229-2523304 B, PYC J11519+0731 B, and GJ 4378 Ab) orbit stars previously reported as candidate YMG members, but instead are likely old (≳1 Gyr) tidally locked spectroscopic binaries without convincing kinematic associations with any known moving group. The high rate of false positives in the form of old active stars with YMG-like kinematics underscores the importance of radial velocity and parallax measurements to validate candidate young stars identified via proper motion and activity selection alone. Finally, we spectroscopically confirm the cool temperature and substellar nature of HD 23514 B, a recently discovered M8 benchmark brown dwarf orbiting the dustiest-known member of the

  9. PLANETS AROUND LOW-MASS STARS (PALMS). V. AGE-DATING LOW-MASS COMPANIONS TO MEMBERS AND INTERLOPERS OF YOUNG MOVING GROUPS

    SciTech Connect

    Bowler, Brendan P.; Montet, Benjamin T.; Riddle, Reed; Shkolnik, Evgenya L.; Flagg, Laura; Liu, Michael C.; Howard, Andrew W.; Aller, Kimberly M.; Best, William M. J.; Kotson, Michael C.; Baranec, Christoph; Schlieder, Joshua E.; Mann, Andrew W.; Dupuy, Trent J.; Hinkley, Sasha; Crepp, Justin R.; Johnson, John Asher; Weinberger, Alycia J.; Allers, Katelyn N.; Herczeg, Gregory J.; and others

    2015-06-10

    We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7–M4.5), most of which have recently been identified as candidate members of nearby young moving groups (YMGs; 8–120 Myr) in the literature. Three of these are new companions identified in our AO imaging survey, and two others are confirmed to be comoving with their host stars for the first time. The inferred masses of the companions (∼10–100 M{sub Jup}) are highly sensitive to the ages of the primary stars; therefore we critically examine the kinematic and spectroscopic properties of each system to distinguish bona fide YMG members from old field interlopers. The new M7 substellar companion 2MASS J02155892–0929121 C (40–60 M{sub Jup}) shows clear spectroscopic signs of low gravity and, hence, youth. The primary, possibly a member of the ∼40 Myr Tuc-Hor moving group, is visually resolved into three components, making it a young low-mass quadruple system in a compact (≲100 AU) configuration. In addition, Li i λ6708 absorption in the intermediate-gravity M7.5 companion 2MASS J15594729+4403595 B provides unambiguous evidence that it is young (≲200 Myr) and resides below the hydrogen-burning limit. Three new close-separation (<1″) companions (2MASS J06475229–2523304 B, PYC J11519+0731 B, and GJ 4378 Ab) orbit stars previously reported as candidate YMG members, but instead are likely old (≳1 Gyr) tidally locked spectroscopic binaries without convincing kinematic associations with any known moving group. The high rate of false positives in the form of old active stars with YMG-like kinematics underscores the importance of radial velocity and parallax measurements to validate candidate young stars identified via proper motion and activity selection alone. Finally, we spectroscopically confirm the cool temperature and substellar nature of HD 23514 B, a recently discovered M8 benchmark brown dwarf orbiting the

  10. Friendship in school-age boys with autism spectrum disorders: A meta-analytic summary and developmental, process-based model.

    PubMed

    Mendelson, Jenna L; Gates, Jacquelyn A; Lerner, Matthew D

    2016-06-01

    Friendship-making is considered a well-established domain of deficit for children with autism spectrum disorders (ASD; American Psychiatric Association, 2013), with this population sometimes described as incapable of making friends. However, the majority of children with ASD indicate a desire for friends, and many report having friends. To what degree, then, do youth with ASD succeed in achieving friendships with peers? If and when they do succeed, by what means do these friendships emerge relative to models of typically developing (TD) youths' friendships? To address these questions, we first meta-analyzed the descriptive friendship literature (peer-reported sociometrics, self-report, parent-report) among school-age boys with ASD. Using random effects models, we found that youth with ASD do make friends according to peers and parents (Hedges's g > 2.84). However, self-reported friendship quality (Hedges's g = -1.09) and parent- and peer-reported quantity (Hedges's g < -0.63) were poorer than TD peers. We consider these findings in light of 2 conceptual frameworks for understanding social deficits in ASD (social cognition and social motivation theory) and in view of a leading model of friendship in TD youth (Hartup & Stevens, 1997). We then present a model that synthesizes these domains through the construct of social information processing speed, and thereby present the first developmental, process-based model of friendship development among youth with ASD. (PsycINFO Database Record

  11. Formation ages and thermal histories of fracture-filling hematite and Mn-oxide in Precambrian basement from (U-Th)/He dating and 4He/3He diffusion experiments

    NASA Astrophysics Data System (ADS)

    Reiners, P. W.; Shuster, D. L.; Evenson, N.

    2015-12-01

    Secondary Fe- and Mn-oxides in bedrock form from fluid flow associated with events that may not be preserved in stratigraphic records. (U-Th)/He chronometry is well suited for dating these phases but potential diffusive loss of 4He can complicate interpretations. Here we show that measuring He diffusion kinetics of dated samples can resolve whether ages record formation or cooling. Proterozoic (1.6 Ga) volcanics in Aravaipa Canyon, southern Arizona, contain 1.4-1.6-Ga quartz-vein-hosted hematite, as well as 1.0-1.1-Ga hematite precipitated on fractures and overlain by 20-30-Ma Mn-oxide. Hematite 4He/3He age spectra and multi-domain (MD) diffusion models are consistent with a small proportion (4-10%) of domains between 1-500 nm, larger proportions (5-15%) of 1-10 μm domains, and a majority (60-75%) of domains of 80-150 μm. Although the smallest domains would have extremely low He retentivity, models predict bulk "closure temperatures" of 180-200 °C. The 1.4-1.6-Ga quartz-vein hematite likely formed soon after eruption of its host rock, and has not been hotter than ~250 °C for Ma durations. The 1.0-1.1 Ga age of the fracture-fill hematite likely also records the timing of precipitation, but from fluids associated with nearby diabase of the same age. In contrast, the 4He/3He MD model of the 20-30-Ma Mn-oxide requires ~80% of 1-100 nm domains and 20% between 1-10 μm. Although the Mn-oxide likely formed at the same time as the hematite it coats, its age records transient heating from overlying 28-Ma volcanics. In all cases, approximate crystal sizes observed in SEM images are consistent with the predictions of MD modeling, and support the assumed kinetics of He diffusion (~147-157 kJ/mol and ~2.2×10-4 cm2/s for hematite, and ~134 kJ/mol and ~4×10-3 cm2/s for Mn-oxide).These results suggest that specular hematite can have bulk He closure temperatures at least as high as 200 °C and in some cases record precipitation; this is supported by our results on specularite

  12. Bushveld-aged fluid flow, peak metamorphism, and gold mobilization in the Witwatersrand basin, South Africa: Constraints from in situ SHRIMP U-Pb dating of monazite and xenotime

    NASA Astrophysics Data System (ADS)

    Rasmussen, Birger; Fletcher, Ian R.; Muhling, Janet R.; Mueller, Andreas G.; Hall, Greg C.

    2007-10-01

    In situ U-Pb dating of monazite and xenotime in gold reefs and unmineralized greenschist facies sedimentary rocks from the Witwatersrand basin, South Africa, reveals two episodes of tectonothermal activity. A major event between 2.06 and 2.03 Ga is recorded in the Wit-watersrand and Transvaal Supergroups in the northwestern and central basin, and broadly coincides with the ca. 2.06 Ga Bushveld event. In the central and southern basin, a previously unrecognized event has been dated between 2.14 and 2.12 Ga. The widespread geographic and stratigraphic occurrence of Bushveld-aged monazite and xenotime, including both auriferous reefs and unmineralized strata, indicates that metamorphism and fluid flow associated with magmatism was pervasive, affecting most of the succession (>10 km thick) in the central and northern parts of the basin. The metamorphic phosphate dates, which are younger away from the complex, indicate a lag of 20-30 m.y. between emplacement and phosphate growth in the central basin (˜100 km south), suggesting that heat related to magmatism was transferred southward at an average rate of 3-5 mm yr-1. The absence of 2.06-2.03 Ga phosphates in the Welkom goldfield at the southern end of the basin implies that Bushveld-related heating and fluid flow did not affect this part of the basin. The intergrowth of ca. 2.045 Ga monazite with gold in quartz-pebble conglomerate from the West Rand goldfield indicates that fluid flow related to the Bushveld event caused mobilization of gold in the Witwatersrand basin.

  13. New developments with Schmidt-hammer exposure-age dating (SHD): Comparison of mechanical and electronic Schmidt-hammers - towards a conversion factor for Q- and R-values

    NASA Astrophysics Data System (ADS)

    Winkler, Stefan; Matthews, John; Corbett, David

    2014-05-01

    Developed as an instrument for in situ destruction-free testing of concrete hardness in construction works, the Schmidt-hammer has subsequently been introduced and applied in various fields of geomorphology and geology. In the context of investigating Late Glacial and Holocene glacier chronologies, the Schmidt-hammer has been widely used as a relative-age dating technique. Such applications have for example successfully separated moraines formed during different glacier advance periods ('Little Ice Age'-type events). Pilot studies combined Schmidt-hammer measurements with available radiocarbon ages in order to achieve age constraints. Schmidt-hammer exposure-age dating (SHD) combining Schmidt-hammer and terrestrial cosmogenic nuclide dating (TCND) has recently been successfully applied in Norway and New Zealand. Schmidt-hammer tests have also been used to ensure the representativeness of boulders selected for TCND sampling. Especially in mountain regions with a high "geomorphological uncertainty" with the dating of Holocene moraines the inherited multi-proxy approach of SHD owns a considerable potential for reliable investigations of Late Glacial/Holocene glacier chronologies and their palaeoclimatic interpretation. An electronic Schmidt-hammer (named SilverSchmidt) was introduced by the manufacturer of the original mechanical Schmidt-hammer (Proceq SA) a few years ago. It offers especially facilities for much easier data processing and constitutes, therefore, a major improvement and potential replacement for the mechanical Schmidt-hammer. However, its different approach to the measurement of surface hardness - based on Q-(velocity) values instead of R-(rebound) values - means that measurements from the two instruments are not easily interconvertible. Prior to any considerations of using the instruments interchangeably or replacing the mechanical Schmidt-hammer in future studies with the SilverSchmidt, comparative tests under field conditions need to be undertaken

  14. The influence of year, laying date, egg fertility and incubation, individual hen, hen age and mass and clutch size on maternal immunoglobulin Y concentration in captive Steller's and spectacled eider egg yolk.

    PubMed

    Counihan, Katrina L; Maniscalco, John M; Bozza, Maryann; Hendon, Jill M; Hollmén, Tuula E

    2015-09-01

    Steller's eiders and spectacled eiders are sea duck species whose populations have declined significantly and infectious diseases could influence offspring survival. Therefore, the maternal transfer of immunoglobulin Y (IgY) into yolk was investigated in captive Steller's and spectacled eiders during the 2007-2013 breeding seasons. This project had two objectives: establish baseline IgY levels in Steller's and spectacled eider yolk under controlled captive conditions and evaluate the effect of year, laying date, egg fertility, egg incubation duration, individual hen, hen age and mass, and laying order to determine which variables influenced IgY levels. Average IgY concentrations were 0.03-0.48 mg ml(-1) in Steller's eider yolk and 0.10-0.51 mg ml(-1) in spectacled eider yolk. The year and individual hen influenced IgY concentration in Steller's and spectacled eider yolk. The laying date was negatively correlated with egg IgY levels for most Steller's eider hens, but laying order was positively correlated with egg IgY concentration for spectacled eiders.

  15. The Properties of Primordial Stars and Galaxies measured from the 21-cm Global Spectrum using the Dark Ages Radio Explorer (DARE)

    NASA Astrophysics Data System (ADS)

    Burns, Jack O.; Bowman, Judd D.; Bradley, Richard F.; Fialkov, Anastasia; Furlanetto, Steven R.; Jones, Dayton L.; Kasper, Justin; Loeb, Abraham; Mirocha, Jordan; Monsalve, Raul A.; Rapetti, David; Tauscher, Keith; Wollack, Edward

    2017-01-01

    DARE is a mission concept designed to observe the formation of primordial stars, black holes, and galaxies (z=11-35) by measuring their spectral effects on the redshifted 21-cm hydrogen line. The UV and X-ray radiation emitted by these first objects ionized and heated the intergalactic medium and imprinted characteristic features in the 21-cm spectrum. The 1.4 GHz signal is redshifted into the radio band 40-120 MHz. DARE will take advantage of the quietest RF environment in the inner solar system by using the Moon as a shield from human radio frequency interference and solar emissions via observations on the lunar farside. DARE’s science objectives are to determine: when the first stars turned on and their properties, when the first black holes began accreting and their masses, the reionization history of the early Universe, and if evidence exists for exotic physics in the Dark Ages such as Dark Matter decay. Wideband crossed-dipole antennas, pilot tone stablized radiometric receivers, a polarimeter, and a digital spectrometer constitute the science instrument. DARE’s radiometer is precisely calibrated with a featureless spectral response, controlled systematics, and heritage from CMB missions. Models for the instrument main beam and sidelobes, antenna reflection coefficient, gain variations, and calibrations will be validated with electromagnetic simulations, laboratory and anechoic chamber measurements, and verified on-orbit. The unique frequency structure of the 21-cm spectrum, its uniformity over large angular scales, and its unpolarized state are unlike the spectrally featureless, spatially-varying, polarized emission of the bright Galactic foreground, allowing the signal to be cleanly separated from the foreground. The 21-cm signal will be extracted in the presence of foregrounds using a Bayesian framework with a Markov Chain Monto Carlo (MCMC) numerical inference technique. The DARE data analysis pipeline enables efficient, simultaneous, and self

  16. Peer involvement in adolescent dating violence.

    PubMed

    Stephenson, Pam S; Martsolf, Donna; Draucker, Claire Burke

    2013-06-01

    This study investigated the ways in which peers are involved in adolescent dating violence. Eighty-eight young adults aged 18-21 were interviewed and asked to reflect on aggressive dating relationships they experienced as teens. The researchers used grounded theory to analyze the data. Findings showed that male and female peers were involved in adolescent dating violence in unique ways. Male peers were involved in dating violence by participating in the aggression, agitating the aggression, being the competition, trivializing the aggression, and keeping tabs on the recipient. Female peers were involved in dating violence by deserting the recipient, cheating with the boyfriend, being the audience, needling the male dating partner, and helping the recipient. Male and female peers were involved similarly in adolescent dating violence by confronting the partner. School nurses working with adolescents are uniquely positioned to approach adolescents about dating violence. Interventions aimed at promoting discussions with adolescents are discussed.

  17. Hydrogeology, Ground-Water-Age Dating, Water Quality, and Vulnerability of Ground Water to Contamination in a Part of the Whitewater Valley Aquifer System near Richmond, Indiana, 2002-2003

    USGS Publications Warehouse

    Buszka, Paul M.; Watson, Lee R.; Greeman, Theodore K.

    2007-01-01

    Results of detailed water-quality analyses, ground-waterage dating, and dissolved-gas analyses indicated the vulnerability of ground water to specific types of contamination, the sequence of contaminant introduction to the aquifer relative to greenfield development, and processes that may mitigate the contamination. Concentrations of chloride and sodium and chloride/bromide weight ratios in sampled water from five wells indicated the vulnerability of the upper aquifer to roaddeicer contamination. Ground-water-age estimates from these wells indicated the onset of upgradient road-deicer use within the previous 25 years. Nitrate in the upper aquifer predates the post-1972 development, based on a ground-water-age date (30 years) and the nitrate concentration (5.12 milligrams per liter as nitrogen) in water from a deep well. Vulnerability of the aquifer to nitrate contamination is limited partially by denitrification. Detection of one to four atrazine transformation products in water samples from the upper aquifer indicated biological and hydrochemical processes that may limit the vulnerability of the ground water to atrazine contamination. Microbial processes also may limit the aquifer vulnerability to small inputs of halogenated aliphatic compounds, as indicated by microbial transformations of trichlorofluoromethane and trichlorotrifluoroethane relative to dichlorodifluoromethane. The vulnerability of ground water to contamination in other parts of the aquifer system also may be mitigated by hydrodynamic dispersion and biologically mediated transformations of nitrate, pesticides, and some organic compounds. Identification of the sequence of contamination and processes affecting the vulnerability of ground water to contamination would have been unlikely with conventional assessment methods.

  18. Potential improvement of Schmidt-hammer exposure-age dating (SHD) of moraines in the Southern Alps, New Zealand, by application of the new electronic Schmidt-hammer (SilverSchmidt)

    NASA Astrophysics Data System (ADS)

    Winkler, Stefan; Corbett, David

    2014-05-01

    The Southern Alps of New Zealand are among the few key study sites for investigating Holocene glacier chronologies in the mid-latitudinal Southern Hemisphere. Their characteristic highly dynamic geomorphological process systems prove, however, to be a considerable challenge for all attempts to date and palaeoclimatologically interpret the existing Holocene moraines record. As a multi-proxy approach combining 10Be terrestrial cosmogenic nuclide dating (TCND) with Schmidt-hammer testing, the recently developed Schmidt-hammer exposure-age dating (SHD) has already shown its potential in this study area (cf. Winkler 2005, 2009, 2013). An electronic Schmidt-hammer (named SilverSchmidt) was introduced by the manufacturer of the original mechanical Schmidt-hammer (Proceq SA) a few years ago. It offers, in particular, facilities for much easier data processing and constitutes a major improvement and potential replacement for the mechanical Schmidt-hammer. However, its different approach to the measurement of surface hardness - based on Q-(velocity) values instead of R-(rebound) values - is a potential drawback. This difference effectively means that measurements from the two instruments are not easily interconvertible and, hence, that the instruments cannot be used interchangeably without previous comparative tests of both instruments under field conditions. Both instruments used in this comparative study were N-type models with identical impact energy of 2.207 Nm for the plunger. To compare both instruments and explore interconvertibility, parallel measurements were performed on a selected number of boulders (10 boulders per site with 5 impacts each, at least 2 sites per moraine) on moraines of homogeneous lithology but different established ages covering the entire Holocene and the Late Glacial. All moraines are located east of the Main Divide of the Southern Alps at Mueller Glacier, Tasman Glacier, and in the outer Tasman River Valley. All paired samples (n = 50) were

  19. A Diagnostically Promising Technique for Tallying Nominal Reference Errors in the Narratives of School-Aged Children with Foetal Alcohol Spectrum Disorders (FASD)

    ERIC Educational Resources Information Center

    Thorne, John C.; Coggins, Truman

    2008-01-01

    Background: Foetal Alcohol Spectrum Disorders (FASD) include the range of disabilities that occur in children exposed to alcohol during pregnancy, with Foetal Alcohol Syndrome (FAS) on the severe end of the spectrum. Clinical research has documented a range of cognitive, social, and communication deficits in FASD and it indicates the need for…

  20. Zellweger Spectrum

    MedlinePlus

    ... Resources Conference News Contact Us Donate The Zellweger Spectrum Zellweger Syndrome, Neonatal Adrenoleukodystrophy (NALD), and Infantile Refsum’s ... of severity of disease. What causes the Zellweger spectrum of diseases? As we mentioned, disorders of the ...

  1. Laboratory for Radiokrypton Dating

    NASA Astrophysics Data System (ADS)

    Lu, Z.; Bailey, K.; Jiang, W.; Müller, P.; O'Connor, T. P.; Zappala, J. C.

    2013-12-01

    Due to its simple production and transport processes in the terrestrial environment, the long-lived noble-gas isotope 81Kr (half-life = 230 kyr) is the ideal tracer for studying old water and ice in the age range of 10^5-10^6 years, a range beyond the reach of 14C. 81Kr dating, a concept pursued in the past four decades by numerous laboratories employing a variety of techniques, is now available for the first time to the earth science community at large. This is made possible by the development of ATTA-3 (Jiang et al., GCA 91, 1-6; 2012), an efficient and selective atom counter based on the Atom Trap Trace Analysis method (Chen et al., Science 286, 1139-1141; 1999). The instrument is capable of measuring both 81Kr/Kr and 85Kr/Kr ratios of environmental samples in the range of 10^-14-10^-10. For 81Kr-dating in the age range of 150 - 1,500 kyr, the required sample size is 5 - 10 micro-L STP of krypton gas, which can be extracted from approximately 100 - 200 kg of water or 40 - 80 kg of ice. For 85Kr/Kr analysis, the required sample size is generally smaller by an order of magnitude because of the isotope's higher initial abundance in the atmosphere. The Laboratory for Radiokrypton Dating is currently equipped to analyze up to 120 samples per year. With future equipment upgrades, this limit can be increased as demand grows. In the period since November 2011, the Laboratory has measured both 81Kr/Kr and 85Kr/Kr ratios in over 50 samples that had been extracted by collaborators from six different continents. The samples were from groundwater wells in the Great Artesian Basin (Australia), Guarani Aquifer (Brazil), and Locust Grove (Maryland); from brine wells of the Waste Isolation Pilot Plant (New Mexico); from geothermal steam vents in Yellowstone National Park; from near-surface ice at Taylor Glacier, Antarctica; and from deep mines in South Africa. Sample collection and purification was performed by groups including the University of Illinois at Chicago, University

  2. Developing 226Ra and 227Ac age-dating techniques for nuclear forensics to gain insight from concordant and non-concordant radiochronometers

    SciTech Connect

    Kayzar, Theresa M.; Williams, Ross W.

    2015-09-26

    The model age or ‘date of purification’ of a nuclear material is an important nuclear forensic signature. In this study, chemical separation and MC-ICP-MS measurement techniques were developed for 226 Ra and 227Ac: grand-daughter nuclides in the 238U and 235U decay chains respectively. The 230Th-234U, 226Ra-238U, 231Pa-235U, and 227Ac-235U radiochronometers were used to calculate model ages for CRM-U100 standard reference material and two highly-enriched pieces of uranium metal from the International Technical Working Group Round Robin 3 Exercise. In conclusion, the results demonstrate the accuracy of the 226Ra-238U and 227Ac-235U chronometers and provide information about nuclide migration during uranium processing.

  3. Food Product Dating

    MedlinePlus

    ... of date you might find on a meat, poultry, or egg product label. Are dates required on ... is not required by Federal regulations. For meat, poultry, and egg products under the jurisdiction of the ...

  4. Electron-microprobe Th-U-Pb monazite dating in Early-Palaeozoic high-grade gneisses as a completion of U-Pb isotopic ages (Wilson Terrane, Antarctica)

    NASA Astrophysics Data System (ADS)

    Schulz, B.; Schüssler, U.

    2013-08-01

    The electron microprobe (EMP) Th-U-Pb monazite bulk chemical dating method was applied to granulite-facies rocks of the Wilson Terrane in Antarctica. A combination of this method to isotopic U-Pb-SHRIMP ages for the evaluation of metamorphic processes required the analysis of reference monazites. These can be subdivided into three groups: a) Monazite with variable total Pb at constant Th (e.g. VK-1) is unsuitable for EMP data evaluation; b) Monazite with highly variable total Pb and Th, but with at least some Th/Pb approximating an apparent isochrone (e.g. MPN) is partly useful; and c) Monazite with constant Th/Pb at high Th (e.g. Madmon monazite) is best suitable for the combined approach and can be additionally used to improve the Th calibration for EMP. Study of monazite in grain mounts and in thin sections led to partly different but complementary results: Older monazites with EMP ages up to 680 Ma occur mainly in a grain mount from diatexite and metatexite and are interpreted as detrital relics. Some of these monazites show structures and mineral-chemical zonation trends resembling metasomatism by alkali-bearing fluids. A marked mobility of Th, P, Ce, Si and U is observed. The age of the metasomatic event can be bracketed between 510 and 450 Ma. Furthermore, in the grain mount and in numerous petrographic thin sections of migmatites and gneisses, the EMP Th-U-Pb and SHRIMP U-Pb monazite data uniformly signal a major metamorphic event with a medium-pressure granulite facies peak between 512 and 496 Ma. Subsequent isothermal uplift and then amphibolite-facies conditions between 488 and 466 Ma led to crystallisation of pristine monazite. The high-grade metamorphic event, related to the Ross Orogeny, can be uniformly traced more than 600 km along strike in the Wilson Terrane.

  5. High-Resolution Inductively Coupled Plasma Optical Emission Spectrometry for (234)U/(238)Pu Age Dating of Plutonium Materials and Comparison to Sector Field Inductively Coupled Plasma Mass Spectrometry.

    PubMed

    Krachler, Michael; Alvarez-Sarandes, Rafael; Rasmussen, Gert

    2016-09-06

    spectrometric approach and thus effectively adds to the quality assurance of (234)U/(238)Pu age dates.

  6. Peer Involvement in Adolescent Dating Violence

    ERIC Educational Resources Information Center

    Stephenson, Pam S.; Martsolf, Donna; Draucker, Claire Burke

    2013-01-01

    This study investigated the ways in which peers are involved in adolescent dating violence. Eighty-eight young adults aged 18-21 were interviewed and asked to reflect on aggressive dating relationships they experienced as teens. The researchers used grounded theory to analyze the data. Findings showed that male and female peers were involved in…

  7. Radiocarbon dating of the Shroud of Turin

    NASA Astrophysics Data System (ADS)

    Damon, P. E.; Donahue, D. J.; Gore, B. H.; Hatheway, A. L.; Jull, A. J. T.; Linick, T. W.; Sercel, P. J.; Toolin, L. J.; Bronk, C. R.; Hall, E. T.; Hedges, R. E. M.; Housley, R.; Law, I. A.; Perry, C.; Bonani, G.; Trumbore, S.; Woelfli, W.; Ambers, J. C.; Bowman, S. G. E.; Leese, M. N.; Tite, M. S.

    1989-02-01

    Very small samples from the Shroud of Turin have been dated by accelerator mass spectrometry in laboratories at Arizona, Oxford and Zurich. As controls, three samples whose ages had been determined independently were also dated. The results provide conclusive evidence that the linen of the Shroud of Turin is mediaeval.

  8. Dating of ballpoint pen ink.

    PubMed

    Hofer, R

    2004-11-01

    In this paper we describe a case in which a cash book, dated of the year 2000, was sent to the Forensic Science Division, Document Laboratory, Zurich Canton Police in March 2003. The questioned document was a list of 29 pages containing a consecutive handwritten numbering and dated entries (payments) made of blue ballpoint pen ink. By definition, a cash book has to be written by hand and the entries have to be made daily. The questioned document was suspected to have been written within a short period (e.g., a few hours) and backdated. The document lab was asked to determine the date of the entries of the questioned list. On one hand, we were asked, if the cash book had been kept on account consecutively during the period of one year, and on the other hand, the judges were interested in knowing, if the document could have been written in 2003 and back dated to 2000. To answer these questions, the document was examined for latent elements by electrostatic detection device (ESDA). The relative dating of the entries was performed by the quantification of the ballpoint pen ink dyes and their degradation products using HPLC. Results show that it is possible to determine the relative age of entries written by ballpoint pen within a relatively short time scale, if storage and supporting material of the different samples are the same or at least similar.

  9. Dating of Modern Human Evolution

    NASA Astrophysics Data System (ADS)

    Grun, R.

    Dating studies on palaoeanthropological sites is usually carried out on material associ- ated with the human remains, such as the sediment, charcoal or other fauna rather than the human specimen itself. The reason lies in the fact that most dating techniques are destructive and because the hominid remains are too rare to be sacrificed for dating. This indirect dating approach is in many cases not satisfactory, because: (i) the human remains are often buried into the sediments and the association with other materials is uncertain (e.g. Skhul, Qafzeh, etc.); (ii) faunal remains or minerals from the sediment are re-worked from older deposits (see e.g. present discussion of the age of the Homo erectus remains in Indonesia; (iii) the hominid fossils were discovered at a time when no careful excavations were carried out and it is impossible to correlate the specimen with other datable material (which applies tonearly 90% of all palaeoanthropological specimens). For example, the hominid burial site of Qafzeh in Israel has been dated by several independent dating laboratories with a multitude of methods. However, the data are still not accepted by some because the dating has not been carried out on the hominid specimen. Until recently, hominid fossils could only be dated by radiocarbon. This method reaches back to about 40,000 years. As a consequence, all the older fossils could not be analysed and many important questions in our understanding of human evolution could not be addressed. Human remains are scarce and extremely valuable, therefore any sort of destruction has to be kept to an absolute minimum. This is of particular importance in Australia where any human fossils are sacred. Thus, for the analysis of hominid material it was necessary to develop a more or less non-destructive techniques. This has been ac- complished in recent years by the application of ESR dating of tooth enamel and a combination of gamma spectrometric and TIMS U-series dating of bones. The exam

  10. Bullying Predicts Reported Dating Violence and Observed Qualities in Adolescent Dating Relationships.

    PubMed

    Ellis, Wendy E; Wolfe, David A

    2015-10-01

    The relationship between reported bullying, reported dating violence, and dating relationship quality measured through couple observations was examined. Given past research demonstrating similarity between peer and dating contexts, we expected that bullying would predict negative dating experiences. Participants with dating experience (n = 585; 238 males, M(age) = 15.06) completed self-report assessments of bullying and dating violence perpetration and victimization. One month later, 44 opposite-sex dyads (M(age) = 15.19) participated in behavioral observations. In 10-min sessions, couples were asked to rank and discuss areas of relationship conflict while being video-recorded. Qualities of the relationship were later coded by trained observers. Regression analysis revealed that bullying positively predicted dating violence perpetration and victimization. Self-reported bullying also predicted observations of lower relationship support and higher withdrawal. Age and gender interactions further qualified these findings. The bullying of boys, but not girls, was significantly related to dating violence perpetration. Age interactions showed that bullying was positively predictive of dating violence perpetration and victimization for older, but not younger adolescents. Positive affect was also negatively predicted by bullying, but only for girls. These findings add to the growing body of evidence that adolescents carry forward strategies learned in the peer context to their dating relationships.

  11. Dating the Crucifixion

    NASA Astrophysics Data System (ADS)

    Humphreys, Colin J.; Waddington, W. G.

    1983-12-01

    The date of the Crucifixion has been debated for many years, but there has been no agreement on the year nor the day. Astronomical calculations have now been used to reconstruct the Jewish calendar in the first century AD and to date a lunar eclipse that biblical and other references suggest followed the Crucifixion. The evidence points to Friday 3 April AD 33 as the date when Jesus Christ died.

  12. Thermoluminescence dating of Australian palaeo-earthquakes

    USGS Publications Warehouse

    Hutton, J.T.; Prescott, J.R.; Bowman, J.R.; Dunham, M.N.E.; Crone, A.J.; Machette, M.N.; Twidale, C.R.

    1994-01-01

    Thermoluminescence (TL) dating is a useful tool for determining the age of prehistoric earthquakes by dating deposits that are stratigraphically related to fault scarps that formed during the earthquakes. TL dating of aeolian sand in the area of the 1988 Tennant Creek, Northern Territory, earthquakes provides evidence that similar earthquakes have not ruptured the causative faults for at least 50 ka. Pilot TL measurements of deposits associated with the Roopena and Ash Ridge fault scarps near Whyalla on Eyre Peninsula, South Australia, suggest an age of 140 ka for the Quaternary deposits associated with the formation of the scarps. ?? 1994.

  13. Spectrum Recombination.

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    1984-01-01

    Describes several methods of executing lecture demonstrations involving the recombination of the spectrum. Groups the techniques into two general classes: bringing selected portions of the spectrum together using lenses or mirrors and blurring the colors by rapid movement or foreshortening. (JM)

  14. Isotope age of the rare metal pegmatite formation in the Kolmozero-Voron'ya greenstone belt (Kola region of the Fennoscandian shield): U-Pb (TIMS) microlite and tourmaline dating

    NASA Astrophysics Data System (ADS)

    Kudryashov, Nikolay; Lyalina, Ludmila; Mokrushin, Artem; Zozulya, Dmitry; Groshev, Nikolay; Steshenko, Ekaterina; Kunakkuzin, Evgeniy

    2016-04-01

    surface contamination being placed the ultrasonic bath with the 7N HNO3 solution. The discordia constructed for seven measured microlite weights is characterized by upper intercepts with concordia at 2454±8 Ma, which probably reflects the time of rare metal pegmatite crystallization, coeval with the age of tourmaline granites. Taking into consideration the obtained U--Pb age of microlite, it may be assumed that the tourmaline granites dated back to 2520±70 Ma served as the most probable parental rocks for rare metal pegmatites of the Vasin-Myl'k deposit. The work is supported by RFBR No 16-05-00367, No 16-05-00427 and project No 0231-2015-0005

  15. Chemical Principles Revisited: Archaeological Dating.

    ERIC Educational Resources Information Center

    Rowe, M. W.

    1986-01-01

    Discusses methods used to date archaeological artifacts and other remains. They include: (1) nuclear dating techniques (radiocarbon dating, accelerator radiocarbon dating, thermoluminescence, and others); (2) chemical dating techniques (amino acid racemization, obsidian hydration dating, elemental content changes, and thermal analysis dating); and…

  16. Screening for Autistic Spectrum in Children Aged 14 to 15 Months. I: The Development of the Early Screening of Autistic Traits Questionnaire (ESAT)

    ERIC Educational Resources Information Center

    Swinkels, Sophie H. N.; Dietz, Claudine; van Daalen, Emma; Kerkhof, Ine H. G. M.; van Engeland, Herman; Buitelaar, Jan K.

    2006-01-01

    This article describes the development of a screening instrument for young children. Screening items were tested first in a non-selected population of children aged 8-20 months (n = 478). Then, parents of children with clinically diagnosed ASD (n = 153, average age 87 months) or ADHD (n = 76, average age 112 months) were asked to score the items…

  17. Increasing Opportunities for Question-Asking in School-Aged Children with Autism Spectrum Disorder: Effectiveness of Staff Training in Pivotal Response Treatment

    ERIC Educational Resources Information Center

    Verschuur, Rianne; Huskens, Bibi; Verhoeven, Ludo; Didden, Robert

    2017-01-01

    Deficits in question-asking are common in children with autism spectrum disorder (ASD). Furthermore, their opportunities to self-initiate questions are often hindered by directive behavior of their conversation partners. This study assessed the effectiveness of staff training in pivotal response treatment (PRT) on staff member-created…

  18. A Comparison of High and Low Dosages of a Component of Milieu Teaching Strategies for Two Preschool-Age Learners with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Julien, Hannah M.; Reichle, Joe

    2016-01-01

    Purpose: The intersection of treatment intensity and communication intervention is an emerging area of investigation. Milieu teaching (MT) approaches for teaching communication skills to children with autism spectrum disorder (ASD) have a substantial evidence base (see Goldstein, 2002). However, a relatively small percentage (37.8%) of MT studies…

  19. Predicting Social and Communicative Ability in School-Age Children with Autism Spectrum Disorder: A Pilot Study of the Social Attribution Task, Multiple Choice

    ERIC Educational Resources Information Center

    Burger-Caplan, Rebecca; Saulnier, Celine; Jones, Warren; Klin, Ami

    2016-01-01

    The Social Attribution Task, Multiple Choice is introduced as a measure of implicit social cognitive ability in children, addressing a key challenge in quantification of social cognitive function in autism spectrum disorder, whereby individuals can often be successful in explicit social scenarios, despite marked social adaptive deficits. The…

  20. A Pilot Study Assessing the Feasibility of a Facial Emotion Training Paradigm for School-Age Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Russo-Ponsaran, Nicole M.; Evans-Smith, Bernadette; Johnson, Jason K.; McKown, Clark

    2014-01-01

    Many children with autism spectrum disorders (ASDs) demonstrate facial emotion recognition and expression impairments. These impairments may contribute to social disability and may put children with ASDs at risk for developing further mental health problems. In this pilot study, we examined the use of a coach- and computer-assisted facial emotion…

  1. The Association between Social Skills and Mental Health in School-Aged Children with Autism Spectrum Disorder, with and without Intellectual Disability

    ERIC Educational Resources Information Center

    Ratcliffe, Belinda; Wong, Michelle; Dossetor, David; Hayes, Susan

    2015-01-01

    Autism Spectrum Disorder (ASD) is associated with social skills deficits and co-occurring mental health difficulties. ASD frequently co-occurs with Intellectual Disability (ID). There is scant literature exploring the association between social skills and mental health in children with ASD, with or without ID. Participants were 292 children aged…

  2. Training Community Mental Health Therapists to Deliver a Package of Evidence-Based Practice Strategies for School-Age Children with Autism Spectrum Disorders: A Pilot Study

    ERIC Educational Resources Information Center

    Brookman-Frazee, Lauren I.; Drahota, Amy; Stadnick, Nicole

    2012-01-01

    Research on moving evidence-based practice (EBP) intervention strategies to community service settings for children with autism spectrum disorders (ASD) is urgently needed. The current pilot study addresses this need by examining the feasibility, acceptability and preliminary outcomes of training therapists practicing in community mental health…

  3. Screening Accuracy of the Parent-Completed Ages and Stages Questionnaires--Second Edition as a Broadband Screener for Motor Problems in Preschoolers with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Vanvuchelen, Marleen; Van Schuerbeeck, Lise; Braeken, Marijke A. K. A.

    2017-01-01

    Children with autism spectrum disorders are at risk for motor problems. However, this area is often overlooked in the developmental evaluation in autism diagnostic clinics. An alternative can be to identify children who should receive intensive motor assessment by using a parent-based screener. The aim of this study was to examine whether the Ages…

  4. Choosing a calving date

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calving date affects cost and timing of production events. Due to the polyestrous nature of beef females, producers can choose a calving date that fits their production system and geographic region. Any time an entire production system is considered, decision making becomes complex. Any calving syst...

  5. Pests of stored dates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dates are a major food crop across a large band of Africa and Eurasia, and to a lesser extent elsewhere. In most of its growing range, dates are threatened with infestation in the field by a complex of pests including nitidulid beetles and pyralid moths of the Subfamily Phycitinae. They are further ...

  6. Date Palm Germplasm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This book chapter reviews date palm genetic resources and their conservation. Date palm (Phoenix dactylifera) is an important food crop in the Middle East and North Africa. Its center of origin and diversity most probably is the area near Iraq/Iran. From there, it spread throughout its present range...

  7. Dating Violence in Russia

    ERIC Educational Resources Information Center

    Lysova, A. V.

    2007-01-01

    The phenomenon of violence in interpersonal relationships has been little studied in Russia, and the phenomenon of violence between dating partners has not been the object of scientific interest at all. The study on which the present article is based was designed to obtain information about the violence in dating among students enrolled in…

  8. Radiometric Dating in Geology.

    ERIC Educational Resources Information Center

    Pankhurst, R. J.

    1980-01-01

    Described are several aspects and methods of quantitatively measuring geologic time using a constant-rate natural process of radioactive decay. Topics include half lives and decay constants, radiogenic growth, potassium-argon dating, rubidium-strontium dating, and the role of geochronology in support of geological exploration. (DS)

  9. A Multi-isotope (B, Sr, O, H) and Age-Dating (3H-3He, 14C) Study of Saline- Water Intrusion and Cross-Formational Flow in the Southern High Plains Aquifer

    NASA Astrophysics Data System (ADS)

    Langman, J. B.; Ellis, A. S.

    2007-12-01

    Identification of aquifer source waters can be difficult with traditional geochemical tracers such as solute concentrations because of the variability of rock-water interactions and complex recharge pathways. The growing use of traditional and non-traditional stable isotopes for identification of hydrologic processes allows the coupling of multiple stable isotopes and ion concentrations for cross-validation and better constraint of influences within an aquifer. A multi-isotope and age-dating study of ground water along the Western Caprock Escarpment of the Southern High Plains was implemented to identify saline-water intrusion and cross-formational flow in the Southern High Plains aquifer. This study coupled major ion and trace element concentrations with the stable isotopes of boron, strontium, hydrogen, and oxygen along with tritium-helium and carbon-14 age dating to identify potential source waters through differences in rock-water interactions and recharge pathways. Ground-water samples were collected from 16 wells, 13 of which were completed in the Ogallala Formation (primary formation of the Southern High Plains aquifer) and three that were completed in a minor aquifer of the underlying Dockum Group. Within the study area, a separate, local flow system originates at a topographic high and flows into a regional flow system defined by a large paleochannel. At a recharge area atop the topographic high and within the regional flow system, ground water is composed of a mixed cation-bicarbonate water, but a sodium-chloride type is present in parts of the local flow system and in ground water from the underlying aquifer in the Dockum Group. Major ion and trace element concentrations and the stable isotope composition of water (δ2H of -43.29 to -71.74 ‰ and δ18O of -5.85 to -9.95 ‰) do not indicate a simple two member mixing scenario but likely multiple sources and cross-formational flow between three formation deposits-- Permian salts, Dockum shales, and

  10. Transmitochondrial mito-miceΔ and mtDNA mutator mice, but not aged mice, share the same spectrum of musculoskeletal disorders.

    PubMed

    Mito, Takayuki; Ishizaki, Hikari; Suzuki, Michiko; Morishima, Hitomi; Ota, Azusa; Ishikawa, Kaori; Nakada, Kazuto; Maeno, Akiteru; Shiroishi, Toshihiko; Hayashi, Jun-Ichi

    2015-01-24

    The spectra of phenotypes associated with aging and mitochondrial diseases sometimes appear to overlap with each other. We used aged mice and a mouse model of mitochondrial diseases (transmitochondrial mito-miceΔ with deleted mtDNA) to study whether premature aging phenotypes observed in mtDNA mutator mice are associated with aging or mitochondrial diseases. Here, we provide convincing evidence that all the mice examined had musculoskeletal disorders of osteoporosis and muscle atrophy, which correspond to phenotypes prevalently observed in the elderly. However, precise investigation of musculoskeletal disorders revealed that the spectra of osteoporosis and muscle atrophy phenotypes in mtDNA mutator mice were very close to those in mito-miceΔ, but different from those of aged mice. Therefore, mtDNA mutator mice and mito-miceΔ, but not aged mice, share the spectra of musculoskeletal disorders.

  11. Paleontological evidence to date the tree of life.

    PubMed

    Benton, Michael J; Donoghue, Philip C J

    2007-01-01

    The role of fossils in dating the tree of life has been misunderstood. Fossils can provide good "minimum" age estimates for branches in the tree, but "maximum" constraints on those ages are poorer. Current debates about which are the "best" fossil dates for calibration move to consideration of the most appropriate constraints on the ages of tree nodes. Because fossil-based dates are constraints, and because molecular evolution is not perfectly clock-like, analysts should use more rather than fewer dates, but there has to be a balance between many genes and few dates versus many dates and few genes. We provide "hard" minimum and "soft" maximum age constraints for 30 divergences among key genome model organisms; these should contribute to better understanding of the dating of the animal tree of life.

  12. 75 FR 75967 - Commerce Spectrum Management Advisory Committee, Call for Applications

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-07

    ... National Telecommunications and Information Administration Commerce Spectrum Management Advisory Committee... interested in serving on the Department of Commerce Spectrum Management Advisory Committee (CSMAC) for new... Information and NTIA Administrator on spectrum policy matters. DATES: Nominations must be postmarked...

  13. Date Rape Drugs

    MedlinePlus

    ... also are used to help people commit other crimes, like robbery and physical assault. They are used ... be misleading because the person who commits the crime might not be dating the victim. Rather, it ...

  14. Date Rape (For Teens)

    MedlinePlus

    ... ve been drinking. continue Protect Yourself The best defense against date rape is to try to prevent ... for help if you feel threatened. Take self-defense courses. These can build confidence and teach valuable ...

  15. Teen Dating Violence

    MedlinePlus

    ... Violence Featured Topic: Opportunities for Action Featured Topic: Bullying Research Featured Topic: Prevent Gang Membership Featured Topic: ... and alcohol Involvement in antisocial behaviors Thoughts about suicide Additionally, youth who are victims of dating violence ...

  16. Ice Core Dating Software for Interactive Dating of Ice Cores

    NASA Astrophysics Data System (ADS)

    Kurbatov, A. V.; Mayewski, P. A.; Abdul Jawad, B. S.

    2005-12-01

    Scientists involved in ice core dating are well familiar with the problem of identification and recording the depth of annual signals using stable isotopes, glaciochemistry, ECM (electrical conductivity), DEP (dielectric properties) and particle counter data. Traditionally all parameters used for ice core dating were plotted as a function of depth, printed and after years were marked on the paper, converted to depth vs. age time scale. To expedite this tedious and manual process we developed interactive computer software, Ice core Dating (ICD) program. ICD is written in Java programming language, and uses GPL and GPL site licensed graphic libraries. The same 3.5 Mb in size pre-compiled single jar file, that includes all libraries and application code, was successfully tested on WinOS, Mac OSX, Linux, and Solaris operating systems running Java VM version 1.4. We have followed the modular design philosophy in our source code so potential integration with other software modules, data bases and server side distributed computer environments can be easily implemented. We expect to continue development of new suites of tools for easy integration of ice core data with other available time proxies. ICD is thoroughly documented and comes with a technical reference and cookbook that explains the purpose of the software and its many features, and provides examples to help new users quickly become familiar with the operation and philosophy of the software. ICD is available as a free download from the Climate Change Institute web site ( under the terms of GNU GPL public license.

  17. Petroleum fingerprinting: Dating a gasoline release

    SciTech Connect

    Johnson, M.D.; Morrison, R.D.

    1996-09-01

    Dating a gasoline releases is particularly important in situations involving a contaminated gasoline service station. Often the station begins under the control of a major oil company, and as it ages and deteriorates it may be operated by a series of smaller operators. When facing a claim for contamination, often operators blame former operators. Fingerprinting is one of several successful methods used to date petroleum releases on contaminated sites. The topics covered in this article are inventory reconciliation; reverse groundwater modeling; hydrocarbon fingerprinting.

  18. Helium-uranium dating of corals.

    NASA Technical Reports Server (NTRS)

    Bender, M. L.

    1973-01-01

    Fanale and Schaeffer (1965) determined He/U ages of corals and other aragonitic fossils, and found that the results generally agreed with independent age estimates. As a more extensive and rigorous test of the reliability of He/U ages of fossil corals, I have determined He/U ages of forty-five independently dated Cenozoic corals. Uranium and thorium isotope compositions and Rn-222 retentivities were also determined as consistency checks. The results indicate that reliable ages are obtained when certain consistency tests are met and specified corrections are made.

  19. Radiocarbon Dating the Anthropocene

    NASA Astrophysics Data System (ADS)

    Chaput, M. A.; Gajewski, K. J.

    2015-12-01

    The Anthropocene has no agreed start date since current suggestions for its beginning range from Pre-Industrial times to the Industrial Revolution, and from the mid-twentieth century to the future. To set the boundary of the Anthropocene in geological time, we must first understand when, how and to what extent humans began altering the Earth system. One aspect of this involves reconstructing the effects of prehistoric human activity on the physical landscape. However, for global reconstructions of land use and land cover change to be more accurately interpreted in the context of human interaction with the landscape, large-scale spatio-temporal demographic changes in prehistoric populations must be known. Estimates of the relative number of prehistoric humans in different regions of the world and at different moments in time are needed. To this end, we analyze a dataset of radiocarbon dates from the Canadian Archaeological Radiocarbon Database (CARD), the Palaeolithic Database of Europe and the AustArch Database of Australia, as well as published dates from South America. This is the first time such a large quantity of dates (approximately 60,000) has been mapped and studied at a global scale. Initial results from the analysis of temporal frequency distributions of calibrated radiocarbon dates, assumed to be proportional to population density, will be discussed. The utility of radiocarbon dates in studies of the Anthropocene will be evaluated and potential links between population density and changes in atmospheric greenhouse gas concentrations, climate, migration patterning and fire frequency coincidence will be considered.

  20. The Realities of Date Rape.

    ERIC Educational Resources Information Center

    Presley, Cara; Watson, Jennifer; Williams, Audrey R.

    This poster presentation addresses the issue of date rape, specifically in the college environment. Highlighted are date rape statistics, demographics, and date rape drugs. Also discussed are date rape warnings and prevention strategies. It is concluded that college and university administrators must place the issue of date rape and acquaintance…

  1. Biodiversity of date palm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The date palm (Phoenix dactylifera) is the dominant component upon which the sustainable biophysical and socio-economic structures of the oasis ecosystem are based; a fruit tree with unique nutritional, biochemical and biophysical characteristics, a rich source of aesthetic and cultural values, and ...

  2. The Dating Game.

    ERIC Educational Resources Information Center

    Zerger, Monte J.

    1998-01-01

    Presents activities to cultivate the tendency to see special qualities in numbers that can be played on certain calendar days. Includes games on the constant of the day, Fibonacci and golden ratio dates, primes, powers, December 25, and the day of the year. (ASK)

  3. Thermoluminescence dating of Hawaiian basalt

    USGS Publications Warehouse

    May, Rodd James

    1979-01-01

    The thermoluminescence (TL) properties of plagioclase separates from 11 independently dated alkalic basalts 4,500 years to 3.3 million years old and 17 tholeiitic basalts 16 years to 450,000 years old from the Hawaiian Islands were investigated for the purpose of developing a TL dating method for young volcanic rocks. Ratios of natural to artificial TL intensity, when normalized for natural radiation dose rates, were used to quantify the thermoluminescence response of individual samples for age-determination purposes. The TL ratios for the alkalic basalt plagioclase were found to increase with age at a predictable exponential rate that permits the use of the equation for the best-fit line through a plot of the TL ratios relative to known age as a TL age equation. The equation is applicable to rocks ranging in composition from basaltic andesite to trachyte over the age range from about 2,000 to at least 250,000 years before present (B.P.). The TL ages for samples older than 50,000 years have a calculated precision of less than :t 10 percent and a potential estimated accuracy relative to potassium-argon ages of approximately :t 10 percent. An attempt to develop a similar dating curve for the tholeiitic basalts was not as successful, primarily because the dose rates are on the average lower than those for the alkalic basalts by a factor of 6, resulting in lower TL intensities in the tholeiitic basalts for samples of equivalent age, and also because the age distribution of dated material is inadequate. The basic TL properties of the plagioclase from the two rock types are similar, however, and TL dating of tholeiitic basalts should eventually be feasible over the age range 10,000 to at least 200,000 years B.P. The average composition of the plagioclase separates from the alkalic basalts ranges from oligoclase to andesine; compositional variations within this range have no apparent effect on the TL ratios. The average composition of the plagioclase from the tholeiitic

  4. How useful are screening instruments for toddlers to predict outcome at age 4? General development, language skills, and symptom severity in children with a false positive screen for autism spectrum disorder.

    PubMed

    Dereu, Mieke; Roeyers, Herbert; Raymaekers, Ruth; Meirsschaut, Mieke; Warreyn, Petra

    2012-10-01

    Screening instruments for autism spectrum disorder (ASD) often generate many false positives. It is argued that these children may have other developmental difficulties and are also in need of thorough assessment and early intervention. The current study looked at the predictive validity of positive screens on the Checklist for Early Signs of Developmental Disorders (CESDD) and the Early Screening of Autistic Traits questionnaire (ESAT) at age 2 towards language, cognitive function, and symptom severity at age 4. Children who screened positive on the ESAT scored lower for both language and cognitive functioning at age 4 compared with children who screened negative on the ESAT. Also, the more signs of ASD that were recognized on the CESDD or ESAT, the lower the scores for language and cognitive functioning at age 4. False positive screens could be differentiated from true positive screens on the CESDD only in symptom severity score on the Autism Diagnostic Observation Schedule (ADOS). It seems that early screeners for ASD also detect children with other developmental disorders and that diagnostic instruments such as the ADOS are warranted to differentiate between children with ASD and other developmental problems.

  5. Dating, Sexual Activity, and Well-Being in Italian Adolescents

    ERIC Educational Resources Information Center

    Ciairano, Silvia; Bonino, Silvia; Kliewer, Wendy; Miceli, Renato; Jackson, Sandy

    2006-01-01

    Associations among dating, sexual activity, gender, and adjustment were investigated in 2,273 Italian adolescents (54% female, ages 14 to 19 years) attending public high schools. After controlling for age and type of school attended, both being in a dating relationship and being male were associated with less alienation, more positive views of the…

  6. Measurement of the di-electron mass spectrum in 12C+12C collisions at 2 AGeV by HADES

    SciTech Connect

    Sudol, Malgorzata

    2006-07-11

    The High Acceptance DiElectron Spectrometer (HADES) has been constructed at the SIS accelerator (GSI, Darmstadt) to investigate electron-positron pairs produced in proton, pion and heavy-ion induced reactions. The physics programme of HADES is focused on in-medium properties of light vector mesons. In this contribution the HADES experiment is outlined and first results obtained for 12C + 12C collisions at 2 AGeV are presented.

  7. Radiometric dating of the Siloam Tunnel, Jerusalem.

    PubMed

    Frumkin, Amos; Shimron, Aryeh; Rosenbaum, Jeff

    2003-09-11

    The historical credibility of texts from the Bible is often debated when compared with Iron Age archaeological finds (refs. 1, 2 and references therein). Modern scientific methods may, in principle, be used to independently date structures that seem to be mentioned in the biblical text, to evaluate its historical authenticity. In reality, however, this approach is extremely difficult because of poor archaeological preservation, uncertainty in identification, scarcity of datable materials, and restricted scientific access into well-identified worship sites. Because of these problems, no well-identified Biblical structure has been radiometrically dated until now. Here we report radiocarbon and U-Th dating of the Siloam Tunnel, proving its Iron Age II date; we conclude that the Biblical text presents an accurate historic record of the Siloam Tunnel's construction. Being one of the longest ancient water tunnels lacking intermediate shafts, dating the Siloam Tunnel is a key to determining where and when this technological breakthrough took place. Siloam Tunnel dating also refutes a claim that the tunnel was constructed in the second century bc.

  8. Gender and age differences in the core triad of impairments in autism spectrum disorders: a systematic review and meta-analysis.

    PubMed

    Van Wijngaarden-Cremers, Patricia J M; van Eeten, Evelien; Groen, Wouter B; Van Deurzen, Patricia A; Oosterling, Iris J; Van der Gaag, Rutger Jan

    2014-03-01

    Autism is an extensively studied disorder in which the gender disparity in prevalence has received much attention. In contrast, only a few studies examine gender differences in symptomatology. This systematic review and meta-analysis of 22 peer reviewed original publications examines gender differences in the core triad of impairments in autism. Gender differences were transformed and concatenated using standardized mean differences, and analyses were stratified in five age categories (toddlerhood, preschool children, childhood, adolescence, young adulthood). Boys showed more repetitive and stereotyped behavior as from the age of six, but not below the age of six. Males and females did not differ in the domain of social behavior and communication. There is an underrepresentation of females with ASD an average to high intelligence. Females could present another autistic phenotype than males. As ASD is now defined according to the male phenotype this could imply that there is an ascertainment bias. More research is needed into the female phenotype of ASD with development of appropriate instruments to detect and ascertain them.

  9. Neighborhood Factors and Dating Violence Among Youth

    PubMed Central

    Johnson, Renee M.; Parker, Elizabeth M.; Rinehart, Jenny; Nail, Jennifer; Rothman, Emily F.

    2015-01-01

    Context The purpose of this review is to summarize the empirical research on neighborhood-level factors and dating violence among adolescents and emerging adults to guide future research and practice. Evidence acquisition In 2015, 20 articles were identified through a search of the literature using PubMed. Eligible articles included those that: (1) had been published in a peer-reviewed journal since 2005; (2) reported a measure of association between at least one neighborhood-level factor and dating violence; and (3) had a study population of youth aged <26 years. We abstracted information about the studies, including measurement of dating violence and neighborhood factors, and measures of effect. Evidence synthesis Results were summarized into three categories based on the aspect of neighborhood which was the focus of the work: demographic and structural characteristics (n=11), neighborhood disorder (n=12), and social disorganization (n=8). There was some evidence to suggest that neighborhood disadvantage is associated with dating violence, but very little evidence to suggest that residence characteristics (e.g., racial heterogeneity) are associated with dating violence. Results do suggest that perceived neighborhood disorder is associated with physical dating violence perpetration, but do not suggest that it is associated with physical dating violence victimization. Social control and community connectedness are both associated with dating violence, but findings on collective efficacy are mixed. Conclusions Existing research suggests that neighborhood factors may be associated with dating violence. However, there is a limited body of research on the neighborhood context of dating violence and more rigorous research is needed. PMID:26296444

  10. 76 FR 77831 - 2012 Presidential Candidate Matching Fund Submission Dates and Post Date of Ineligibility Dates...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-14

    ... Submit Statements of Net Outstanding Campaign Obligations AGENCY: Federal Election Commission. ACTION: Notice of matching fund submission dates and submission dates for statements of net outstanding campaign... statements of net outstanding campaign obligations (``NOCO statement'') after their dates of...

  11. 10Be dating of Neogene halite

    NASA Astrophysics Data System (ADS)

    Belmaker, Reuven; Lazar, Boaz; Beer, Jürg; Christl, Marcus; Tepelyakov, Natalya; Stein, Mordechai

    2013-12-01

    Direct radioactive dating of ancient halite formations is difficult because this mineral typically lacks conventionally datable material. We describe an attempt to date Neogene halite using the cosmogenic isotope 10Be (T1/2 = 1.39 Ma). We dated marine-derived salt deposits from the Sedom and Amora (The Hebrew forms of Sodom and Gomorrah) Formations, Dead Sea basin, Israel. To verify whether Be is incorporated into marine halite we measured the stable isotope 9Be, 7Be (the short lived “cosmogenic brother” of 10Be having T1/2 = 53.3 d), and 10Be in evaporation pans of sea-salt production plants. The data suggest that seawater beryllium is incorporated into the halite with a halite-brine distribution coefficient, (KD) of about unity. A 10Be/9Be decay curve constructed for Sedom Formation halite yielded an age that lies in the range of ∼2-6 Ma. The 10Be decay curve constructed for Sedom Formation halite yielded an age that lies in the range of 3-5 Ma. This age is consistent with previous estimates of the Sedom Formation age. Furthermore, this age lies in the same range of 10Be in situ ages obtained on the lacustrine Erq El Ahmer Formation located in the northern Jordan Valley. This may imply that during the Mid Pliocene the Sedom Lagoon, the water-body that deposited the Sedom Formation, might have been already disconnected from the open sea.

  12. Physical Dating Aggression Growth during Adolescence

    ERIC Educational Resources Information Center

    Nocentini, Annalaura; Menesini, Ersilia; Pastorelli, Concetta

    2010-01-01

    The development of Physical Dating Aggression from the age of 16 to 18 years was investigated in relation to time-invariant predictors (gender, parental education, family composition, number of partners) and to time-varying effects of delinquent behavior and perception of victimization by the partner. The sample consisted of 181 adolescents with a…

  13. Historical Analysis of College Campus Interracial Dating

    ERIC Educational Resources Information Center

    Firmin, Michael W.; Firebaugh, Stephanie

    2008-01-01

    Interracial dating on American campuses has had a relatively stormy past. Until the past three decades or so, it was outlawed in some states. Southern institutions, in particular, such as the infamous Bob Jones University have made this issue divisive even among their own constituencies. Age and generation seem to be cogent factors with younger…

  14. The influence of age at onset and duration of illness on long-term outcome in patients with obsessive-compulsive disorder: a report from the International College of Obsessive Compulsive Spectrum Disorders (ICOCS).

    PubMed

    Dell'Osso, Bernardo; Benatti, Beatrice; Buoli, Massimiliano; Altamura, A Carlo; Marazziti, Donatella; Hollander, Eric; Fineberg, Naomi; Stein, Dan J; Pallanti, Stefano; Nicolini, Humberto; Van Ameringen, Michael; Lochner, Christine; Hranov, Georgi; Karamustafalioglu, Oguz; Hranov, Luchezar; Menchon, Jose M; Zohar, Joseph

    2013-08-01

    Several studies reported a negative effect of early onset and long duration of illness on long-term outcome in psychiatric disorders, including Obsessive-Compulsive Disorder (OCD). OCD is a prevalent, comorbid and disabling condition, associated with reduced quality of life and overall well-being for affected patients and related caregivers. The present multicenter naturalistic study sought to assess the influence of early onset and duration of illness on long-term outcome in a sample of 376 OCD out-patients worldwide, as part of the "International College of Obsessive-Compulsive Spectrum Disorders" (ICOCS) network. Binary logistic regressions were performed with age at the onset and duration of illness, as continuous independent variables, on a series of different outcome dependent variables, including lifetime number of hospitalizations and suicide attempts, poly-therapy and psychiatric comorbidity. Correlations in terms of disability (SDS) were analyzed as well. Results showed that a longer duration of illness (but not earlier age of onset) was associated with hospitalization (odds ratio=1.03, p=0.01), earlier age at onset with CBT (odds ratio=0.94, p<0.001) and both a later age at onset (odds ratio=1.05, p=0.02) and a shorter duration of illness (odds ratio=0.93, p=0.02) with panic disorder comorbidity. In addition, earlier age at onset inversely correlated with higher social disability (r=-0.12, p=0.048) and longer duration of illness directly correlated with higher disability in work, social and family life (r=0.14, p=0.017; r=0.13, p=0.035; r=0.14, p=0.02). The findings from the present large, multicenter study indicate early onset and long duration of illness as overall negative predictors of long-term outcome in OCD.

  15. Première datation des lydiennes paléozoïques dans les Hellénides internes (mont Parnis, Grèce); implications géologiquesFirst age dating of the Lydian stones in the Inner Hellenides (Mount Parnis, Greece); geological significances.

    NASA Astrophysics Data System (ADS)

    Caridroit, Martial; Ferrière, Jacky; Dégardin, Jean-Marie; Vachard, Daniel; Clément, Bernard

    2000-09-01

    Using radiolarian and conodont remains, a Tournaisian age has been obtained from the Lydian rocks (or lydites) of the Parnis Mount (Greece); this result is the first direct age dating of the Lydian rocks of continental Greece. In the same area, some limestone strata, interbedded in sandstones, yield Carboniferous and Permian foraminifers; the established stratigraphy is not consistent and so, the Lydian rocks have to be considered as blocks in an olistostrome unconformably overlain or thrusted by Triassic limestones. Otherwise, the Lydian rocks are interpreted as biogenic siliceous deposits due to the absence of carbonate sedimentation (not as a high siliceous production).

  16. Retrospective Birth Dating of Cells

    SciTech Connect

    L.Spalding, K; Bhardwaj, R D; Buchholz, B A; Druid, H; Frisen, J

    2005-04-19

    The generation of cells in the human body has been difficult to study and our understanding of cell turnover is limited. Extensive testing of nuclear weapons resulted in a dramatic global increase in the levels of the isotope {sup 14}C in the atmosphere, followed by an exponential decrease after the test ban treaty in 1963. We show that the level of {sup 14}C in genomic DNA closely parallels atmospheric levels, and can be used to establish the time point when the DNA was synthesized and cells were born. We use this strategy to determine the age of cells in the cortex of the adult human brain, and show that whereas non-neuronal cells are exchanged, occipital neurons are as old as the individual, supporting the view that postnatal neurogenesis does not take place in this region. Retrospective birth dating is a generally applicable strategy that can be used to measure cell turnover in man under physiological and pathological conditions.

  17. 75 FR 7234 - Commerce Spectrum Management Advisory Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-18

    ... National Telecommunications and Information Administration Commerce Spectrum Management Advisory Committee.... ACTION: Notice of Open Meeting. SUMMARY: This notice announces a public meeting of the Commerce Spectrum... Communications and Information on spectrum policy matters. DATES: The meeting will be held on March 4, 2010,...

  18. Dating Violence among College Students

    ERIC Educational Resources Information Center

    Iconis, Rosemary

    2013-01-01

    Dating violence is a significant problem on college campuses. More than one-fifth of the undergraduate dating population are physically abused by their dating partners and an even greater percentage are psychologically abused. Researchers have identified risk factors for college student dating violence. Preventive interventions are strongly…

  19. Spectrum of congenital defects of the eye and its adnexia in the pediatric age group; experience at a tertiary facility in Nigeria.

    PubMed

    Adekoya, Bola J; Balogun, Modupe M; Balogun, Bola G; Ngwu, Rosemary A

    2015-06-01

    The aim of this study was to investigate the types and presentation pattern of congenital defects of the eye and adnexia in our center. This is a retrospective review of congenital defects of the eye and adnexia over a 20-month period at a tertiary referral center in Lagos, Nigeria. Records were analyzed for age at presentation, laterality, gender, vision assessment, and type(s) of abnormality. Out of 412 pediatric patients, 40 (9.7 %) were seen to have congenital abnormality of the eye and/or its adnexia during the study period. There were 17 (42.5 %) males. Twelve patients (30.0 %) presented with involvement of the right eyes, nine (22.5 %) with left eyes, while 19 (47.5 %) had bilateral involvement. Twenty-eight patients (70.0 %) were aged 1 year or less at the time of presentation. A total of 69 entities were recognized as some children had two or more malformations. The common congenital defects identified were cataract (39.1 %), ptosis (17.4 %), glaucoma (8.7 %), and cornea opacity (7.2 %). Other less common congenital defects include: microphthalmos, anophthalmos, coloboma (lid and iris), dermoid cyst, and aniridia. All of the patients with available visual acuity documentation had visual impairment. A high proportion of the patients were lost to follow-up. Cataract, ptosis, and glaucoma were the commonest congenital defects of the eye and adnexia in our center and were associated with visual impairments. The significant loss of the patients during follow-up needs urgent investigation and attention to forestall this trend.

  20. Fission Spectrum

    DOE R&D Accomplishments Database

    Bloch, F.; Staub, H.

    1943-08-18

    Measurements of the spectrum of the fission neutrons of 25 are described, in which the energy of the neutrons is determined from the ionization produced by individual hydrogen recoils. The slow neutrons producing fission are obtained by slowing down the fast neutrons from the Be-D reaction of the Stanford cyclotron. In order to distinguish between fission neutrons and the remaining fast cyclotron neutrons both the cyclotron current and the pusle amplifier are modulated. A hollow neutron container, in which slow neutrons have a lifetime of about 2 milliseconds, avoids the use of large distances. This method results in much higher intensities than the usual modulation arrangement. The results show a continuous distribution of neutrons with a rather wide maximum at about 0.8 MV falling off to half of its maximum value at 2.0 MV. The total number of netrons is determined by comparison with the number of fission fragments. The result seems to indicate that only about 30% of the neutrons have energies below .8 MV. Various tests are described which were performed in order to rule out modification of the spectrum by inelastic scattering. Decl. May 4, 1951

  1. Vulcanism and Radiocarbon Dates

    DOE R&D Accomplishments Database

    Libby, L. M.; Libby, W. F.

    1972-10-01

    We consider whether the long term perturbation of radiocarbon dates, which is known to be approximately a sin function of period about 8000 years and amplitude of about 8% peak-to-peak, could have been caused in any major part by vulcanism. We conclude that this is not the case. On the contrary, present day volcanoes are a far less important source of inert CO{sub 2} (about 100 fold less) than is man's burning of fossil fuels which has caused the Suess dilution of about 2%. (auth)

  2. Ages and Stages: Teen

    MedlinePlus

    ... Pediatrician Ages & Stages Prenatal Baby Toddler Preschool Gradeschool Teen Dating & Sex Fitness Nutrition Driving Safety School Substance Abuse Young Adult Healthy Children > Ages & Stages > Teen Teen Article Body Adolescence can be a rough ...

  3. Spectrum of physics comprehension

    NASA Astrophysics Data System (ADS)

    Blasiak, W.; Godlewska, M.; Rosiek, R.; Wcislo, D.

    2012-05-01

    The paper presents the results of research on the relationship between self-assessed comprehension of physics lectures and final grades of junior high school students (aged 13-15), high school students (aged 16-18) and physics students at the Pedagogical University of Cracow, Poland (aged 21). Students' declared level of comprehension was measured during a physics lecture on a prearranged scale of 1-10 with the use of a personal response system designed for the purpose of this experiment. Through the use of this tool, we obtained about 2000 computer records of students' declared comprehension of a 45 min lecture, which we named ‘the spectrum of comprehension’. In this paper, we present and analyse the correlation between students' declared comprehension of the content presented in the lecture and their final learning results.

  4. Positives and negatives of online dating according to women 50.

    PubMed

    Vandeweerd, Carla; Myers, Jaime; Coulter, Martha; Yalcin, Ali; Corvin, Jaime

    2016-01-01

    To understand the positives and negatives of online dating according to the lived experience of older women, telephone interviews were conducted with 45 women ages 50+ who date online. Interviews were audio recorded, transcribed verbatim, and thematically team coded. The opportunity to expand one's social network for both friendships and romantic partners, the ability to control dating risks and pace of relationship formation, and knowing more about one's partner were significant reported benefits of online dating. Dating online also includes unique risks, such as pervasive lying, attempted financial exploitation in the form of scammers, and unwanted electronic sexual aggression.

  5. Luminescence dating of ancient Darhad basin, Mongolia

    NASA Astrophysics Data System (ADS)

    Cheul Kim, Jin; Yi, Sangheon; Lim, Jaesoo; Kim, Ju-Yong

    2016-04-01

    Darhad basin is located in the northern Mongolia, in the western end of the Baikal Rift Zone. In contrast to the neighboring Lake Hovsgol, Mongolia's largest and deepest lake, the Darhad is a drained lake basin. It is ~100 km long (north-south), 20-40 km wide and covered by sediments which locally exceed 500 m thickness (Zorin et al., 1989). Darhad basin is characterized by alternating episodes of expansion and desiccation that are closely related with the Pleistocene damming events. Previous studies of the Darhad Basin suggest that the last paleolake was dammed by a large glacier or the sediments (Selivanov, 1967, 1968; Krivonogov et al., 2005; Gillespie et al., 2008). Especially, recent expansion of the paleolake might be caused by the two glacial maxima during MIS 4 and 2. However, glacier-dammed lakes might be short-lived, dried up and permafrost occurred in the drained basin during the Holocene period. The uppermost paleolake sediments (13.2 m depth) are exposed following the curvature of the meandering river (called "Hodon outcrop"). It is considered the most likely site for the youngest paleolake sediments because it is distributed in the northern middle part of the paleolake. Krivonogov et al. 2012 described the Hodon outcrop with the sedimentological and chronological data. Age dating of 16 samples (11 mollusk shells, 5 wood fragments) indicated that Hodon outcrop sediments were deposited between 10.1±7 and 4.9±5 ka. However, the ages obtained on shells much older dates than the matched wood samples because of ingestion of old carbon by mollusks. The age difference between shells and wood fragments is a minimum of 1.73 ka and a maximum of 3.41 ka (average 2.5 ka). In this case, 14C ages from shells should be corrected with appropriate correction factor. However, the old carbon effects could vary temperally and spatially in the Darhad paleolake. The limited number of the 14C ages from wood fragments result in a simple linear trend in the depth-age curve

  6. Radioisotope Dating with Accelerators.

    ERIC Educational Resources Information Center

    Muller, Richard A.

    1979-01-01

    Explains a new method of detecting radioactive isotopes by counting their accelerated ions rather than the atoms that decay during the counting period. This method increases the sensitivity by several orders of magnitude, and allows one to find the ages of much older and smaller samples. (GA)

  7. Contrasting age related changes in autism spectrum disorder phenomenology in Cornelia de Lange, Fragile X, and Cri du Chat syndromes: Results from a 2.5 year follow-up.

    PubMed

    Cochran, Lisa; Moss, Joanna; Nelson, Lisa; Oliver, Chris

    2015-06-01

    Little is known about the way in which the characteristics of autism spectrum disorder (ASD) develop and manifest across the age span in individuals with genetic syndromes. In this study we present findings from a two and a half year follow-up of the characteristics associated with ASD in three syndromes: Cornelia de Lange (CdLS), Fragile X (FXS), and Cri du Chat (CdCS). Parents and carers of 251 individuals (CdLS=67, CdCS=42, and FXS=142) completed the Social Communication Questionnaire (SCQ) at Time 1 (T1) and again two and a half years later (T2). The FXS and CdLS groups were more likely to meet the cut-offs for both autism and ASD and show greater severity of ASD related behaviors, at both T1 and T2, compared to the CdCS group. Older individuals (>15yrs) with CdLS were more likely to meet the cut off for ASD than younger individuals (≤15 yrs) with the syndrome and more likely to show greater severity of social impairments. In FXS repetitive behaviors were found to become less prominent with age and in CdCS social impairments were reported to be more severe with age. There were no significant changes between T1 and T2 in the severity of ASD characteristics in the CdCS and CdLS groups. The FXS group showed significantly fewer repetitive behaviors and less severe impairments in social interaction over this time frame. The findings suggest that while there may be similarities in overall severity and presentation of ASD characteristics in CdLS and FXS, these characteristics have divergent patterns of development within these groups.

  8. Violence in Adolescent Dating Relationships

    ERIC Educational Resources Information Center

    Jouriles, Ernest N.; Platt, Cora; McDonald, Renee

    2009-01-01

    Beginning with a definition of dating and dating violence among adolescents, this article explores the factors which impact such violence. It concludes with a review of two school-based prevention/intervention programs (Safe Dates and The Youth Relationships Project). (Contains 1 table.)

  9. Dating violence and girls in the juvenile justice system.

    PubMed

    Kelly, Patricia J; Cheng, An-Lin; Peralez-Dieckmann, Esther; Martinez, Elisabeth

    2009-09-01

    The purpose of this study is to explore the prevalence and associated behaviors of dating violence among a population of girls in the juvenile justice system. A sample of 590 girls from an urban juvenile justice system completed a questionnaire assessing attitudes and self-efficacy about and occurrence of dating violence. The analysis developed a random effect model to determine a risk profile for dating violence. The strongest predictors of dating violence were (a) initial sexual experience at age 13 or earlier, (b) unwillingness of initial sexual experience, (c) drug use, and (d) low self-efficacy about preventing dating violence. The high prevalence of dating violence and associated behaviors among participants suggests the importance of implementing primary prevention programs to assist preteen girls in delaying initial sexual intercourse and in learning techniques to prevent dating violence.

  10. Autism Spectrum Disorder and Underlying Brain Mechanism in the Oculoauriculovertebral Spectrum

    ERIC Educational Resources Information Center

    Johansson, Maria; Billstedt, Eva; Danielsson, Susanna; Stromland, Kerstin; Miller, Marilyn; Granstrom, Gosta; Flodmark, Olof; Rastam, Maria; Gillberg, Christopher

    2007-01-01

    As part of a multidisciplinary study, the rate of autism spectrum disorder (ASD), learning disability (LD), and brain abnormalities was examined in 20 participants (12 males, 8 females; age range 8mo-17y, mean age 8y 1mo) diagnosed as falling within the oculoauriculovertebral spectrum (OAV). A neuropsychiatric examination was performed, including…

  11. Dating and Sex among Emerging Adults in Nepal

    ERIC Educational Resources Information Center

    Regmi, Pramod R.; van Teijlingen, Edwin R.; Simkhada, Padam; Acharya, Dev R.

    2011-01-01

    Social and cultural changes in Nepal, including better communication facilities and transport, more urbanization and a rising age at which people marry, have created more opportunities for young people for "dating." Our qualitative study explores whether the existence of dating cultures influences young people's sexual behavior in Nepal.…

  12. Dating and Sexual Attitudes in Asian-American Adolescents

    ERIC Educational Resources Information Center

    Lau, May; Markham, Christine; Lin, Hua; Flores, Glenn; Chacko, Mariam R.

    2009-01-01

    Dating behaviors and sexual attitudes of Asian-American youth were examined in a cross-sectional, mixed-methods study in the context of adherence to Asian values, measured by the Asian Values Scale (AVS). In all, 31 Asian-American adolescents (age 14-18 years old) from a Houston community center were interviewed regarding dating behaviors and…

  13. Analytical methods for dating modern writing instrument inks on paper.

    PubMed

    Ezcurra, Magdalena; Góngora, Juan M G; Maguregui, Itxaso; Alonso, Rosa

    2010-04-15

    This work reviews the different analytical methods that have been proposed in the field of forensic dating of inks from different modern writing instruments. The reported works have been classified according to the writing instrument studied and the ink component analyzed in relation to aging. The study, done chronologically, shows the advances experienced in the ink dating field in the last decades.

  14. Suburban Legend: School Cutoff Dates and the Timing of Births

    ERIC Educational Resources Information Center

    Dickert-Conlin, Stacy; Elder, Todd

    2010-01-01

    Many states require children to reach age 5 by a specified date in the calendar year in order to begin kindergarten. We use birth certificate records from 1999 to 2004 to assess whether parents systematically time childbirth before these eligibility cutoff dates to capture the option value of sending their child to school at a relatively young…

  15. Radiation in archaeometry: archaeological dating

    NASA Astrophysics Data System (ADS)

    Martini, Marco; Sibilia, Emanuela

    2001-06-01

    Crystalline inclusions contained in ceramics act as thermoluminescent dosimeters, the irradiation source being the natural radiation environment. Because of this, various ceramic materials (pottery, bricks, cooked clays, bronze clay-cores) have been dated by thermoluminescence (TL). A short review of the main possibilities of TL dating is given, with some examples that enlighten the advantages and limits of this method in the field of archaeological dating, compared to TL dating of buildings. The assessment of the chronology of Valdivia culture (Ecuador), based on a three-year project of TL dating, is presented and discussed. The overall uncertainty at around 4-5% can be considered the best limit presently available. The uncertainty distribution found among 700 archaeological TL datings and for about 500 building TL datings is also presented.

  16. Direct Dating of Hominids Remains In Eurasia

    NASA Astrophysics Data System (ADS)

    Yokoyama, Y.; Falguères, C.

    When archaeological sites are associated with human remains, it is relevant to be able to date those valuable remains for different reasons. The main one is that it avoids the stratigraphical problems which can be due to intrusive burials in the sequence. The other reason consists in the fact that human bones may be encountered out of established stratigraphical context. On the other hand, the majority of dating methods currently used are destructive and can not be applied on these precious samples particularly when they are older than 40,000 years and can not be dated by radiocarbon. Since several years, we have developped a completely non-destructive method which consists in the measurement of human remains using the gamma -ray spectrometry. This technique has been used recently by other laboratories. We present here two important cases for the knowledge of human evolution in Eurasia. The first example is Qafzeh site in Israel where many human skeletons have been unearthed from burials associated with fauna and lithic artefacts. This site has been dated by several independent radiometric methods. So, it was possible to compare our gamma results with the other results yielded by the different methods. The second case concerns the most evolved Homo erectus found in Java, Indonesia, at Ngandong site, close to the Solo river. A recent debate has been focused on the age of these fossils and their direct dating is of outmost importance for the knowledge of settlement of Modern Humans in South-East Asia.

  17. The biology behind lichenometric dating curves.

    PubMed

    Loso, Michael G; Doak, Daniel F

    2006-03-01

    Lichenometry is used to date late-Holocene terminal moraines that record glacier fluctuations. Traditionally, it relies upon dating curves that relate diameters of the largest lichens in a population to surface ages. Although widely used, the technique remains controversial, in part because lichen biology is poorly understood. We use size-frequency distributions of lichens growing on well-dated surfaces to fit demographic models for Rhizocarpon geographicum and Pseudophebe pubescens, two species commonly used for lichenometry. We show that both species suffer from substantial mortality of 2-3% per year, and grow slowest when young-trends that explain a long-standing contradiction between the literatures of lichenometry and lichen biology. Lichenometrists interpret the shape of typical dating curves to indicate a period of rapid juvenile "great growth," contrary to the growth patterns expected by biologists. With a simulation, we show how the "great growth" pattern can be explained by mortality alone, which ensures that early colonists are rarely found on the oldest surfaces. The consistency of our model predictions with biological theory and observations, and with dozens of lichenometric calibration curves from around the world, suggests opportunities to assess quantitatively the accuracy and utility of this common dating technique.

  18. Dating Tips for Divergence-Time Estimation.

    PubMed

    O'Reilly, Joseph E; dos Reis, Mario; Donoghue, Philip C J

    2015-11-01

    The molecular clock is the only viable means of establishing an accurate timescale for Life on Earth, but it remains reliant on a capricious fossil record for calibration. 'Tip-dating' promises a conceptual advance, integrating fossil species among their living relatives using molecular/morphological datasets and evolutionary models. Fossil species of known age establish calibration directly, and their phylogenetic uncertainty is accommodated through the co-estimation of time and topology. However, challenges remain, including a dearth of effective models of morphological evolution, rate correlation, the non-random nature of missing characters in fossil data, and, most importantly, accommodating uncertainty in fossil age. We show uncertainty in fossil-dating propagates to divergence-time estimates, yielding estimates that are older and less precise than those based on traditional node calibration. Ultimately, node and tip calibrations are not mutually incompatible and may be integrated to achieve more accurate and precise evolutionary timescales.

  19. In situ U-Pb rutile dating by LA-ICP-MS: 208Pb correction and prospects for geological applications

    NASA Astrophysics Data System (ADS)

    Zack, Thomas; Stockli, Daniel F.; Luvizotto, George L.; Barth, Matthias G.; Belousova, Elena; Wolfe, Melissa R.; Hinton, Richard W.

    2011-09-01

    Rutile is a common accessory mineral that occurs in a wide spectrum of metamorphic rocks, such as in blueschists, eclogites, and granulites and as one of the most stable detrital heavy minerals in sedimentary rocks. The advent of rutile trace element thermometry has generated increased interest in a better understanding of rutile formation. This study documents important analytical advances in in situ LA-ICP-MS U/Pb geochronology of rutile: (1) Matrix matching, necessary for robust in situ dating is fulfilled by calibrating and testing several rutile standards (R10, R19, WH-1), including the presentation of new TIMS ages for the rutile standard R19 (489.5 ± 0.9 Ma; errors always stated as 2 s). (2) Initial common lead correction is routinely applied via 208Pb, which is possible due to extremely low Th/U ratios (usually <0.003) in most rutiles. Employing a 213 nm Nd:YAG laser coupled to a quadrupole ICP-MS and using R10 as a primary standard, rutile U/Pb concordia ages for the two other rutile standards (493 ± 10 Ma for R19; 2640 ± 50 Ma for WH-1) and four rutile-bearing metamorphic rocks (181 ± 4 Ma for Ivrea metapelitic granulite; 339 ± 7 Ma for Saidenbach coesite eclogite; 386 ± 8 Ma for Fjortoft UHP metapelite; 606 ± 12 Ma for Andrelandia metepelitic granulite) always agree within 2% with the reported TIMS ages and other dating studies from the same localities. The power of in situ U/Pb rutile dating is illustrated by comparing ages of detrital rutile and zircon from a recent sediment from the Christie Domain of the Gawler Craton, Australia. While the U/Pb age spectrum from zircons show several pronounced peaks that are correlated with magmatic episodes, rutile U/Pb ages are marked by only one pronounced peak (at ca 1,675 Ma) interpreted to represent cooling ages of this part of the craton. Rutile thermometry of the same detrital grains indicates former granulite-facies conditions. The methods outlined in this paper should find wide application in studies

  20. Evidence for prolonged mid-Paleozoic plutonism and ages of crustal sources in east-central Alaska from SHRIMP U-Pb dating of syn-magmatic, inherited, and detrital zircon

    USGS Publications Warehouse

    Dusel-Bacon, C.; Williams, I.S.

    2009-01-01

    Sensitive high-resolution ion microprobe (SHRIMP) U-Pb analyses of igneous zircons from the Lake George assemblage in the eastern Yukon-Tanana Upland (Tanacross quadrangle) indicate both Late Devonian (???370 Ma) and Early Mississippian (???350 Ma) magmatic pulses. The zircons occur in four textural variants of granitic orthogneiss from a large area of muscovite-biotite augen gneiss. Granitic orthogneiss from the nearby Fiftymile batholith, which straddles the Alaska-Yukon border, yielded a similar range in zircon U-Pb ages, suggesting that both the Fiftymile batholith and the Tanacross orthogneiss body consist of multiple intrusions. We interpret the overall tectonic setting for the Late Devonian and Early Mississippian magmatism as an extending continental margin (broad back-arc region) inboard of a northeast-dipping (present coordinates) subduction zone. New SHRIMP U-Pb ages of inherited zircon cores in the Tanacross orthogneisses and of detrital zircons from quartzite from the Jarvis belt in the Alaska Range (Mount Hayes quadrangle) include major 2.0-1.7 Ga clusters and lesser 2.7-2.3 Ga clusters, with subordinate 3.2, 1.4, and 1.1 Ga clusters in some orthogneiss samples. For the most part, these inherited and core U-Pb ages match those of basement provinces of the western Canadian Shield and indicate widespread potential sources within western Laurentia for most grain populations; these ages also match the detrital zircon reference for the northern North American miogeocline and support a correlation between the two areas.

  1. 40Ar/39Ar dating of the Siberian Traps, USSR: Evaluation of the ages of the two major extinction events relative to episodes of flood-basalt volcanism in the USSR and the Deccan Traps, India

    SciTech Connect

    Baksi, A.K. ); Farrar, E. )

    1991-05-01

    {sup 40}Ar/{sup 39}Ar incremental-heating studies have been carried out on three whole-rock specimens from the Siberian Traps. A basalt lava flow from the lowermost horizon yields and age of 238.4 {plus minus} 1.4 Ma (1{sigma} error). A second basalt lava flow from the top of the section, {approximately}800 m above the first specimen, yields an age of 229.9 {plus minus} 2.3 Ma, indicating that the duration of volcanism was {approximately}5{minus}10 m.y. A doleritic dike intrusive into the lower parts of the Siberian Traps contains excess argon and yields an isochron age of 234 {plus minus} 7 Ma. Critical reexamination of relevant radiometric data relating two separate episodes of flood-basalt volcanism to global faunal extinctions suggests the volcanic event forming the most voluminous sections of the Deccan Traps, India, was coincident to within {plus minus}1 m.y. with the time of the Cretaceous/Tertiary boundary. However, the onset of volcanism in the Siberian Traps apparently occurred at a time postdating that of the Permian/Triassic boundary.

  2. Detail view of date stone marking the founding of the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view of date stone marking the founding of the Emmanuel Christian Community Church congregation - Reformed Episcopal Church of the Rock of Ages, 1210 West Lanvale Street, Baltimore, Independent City, MD

  3. Dating Relationships in Older Adulthood: A National Portrait

    PubMed Central

    Brown, Susan L.; Shinohara, Sayaka K.

    2013-01-01

    Dating in later life is likely common, especially as the proportion of older adults who are single continues to rise. Yet there are no recent national estimates of either the prevalence or factors associated with dating during older adulthood. Using data from the 2005-2006 National Social Life, Health, and Aging Project, a nationally representative sample of 3,005 individuals ages 57-85, the authors constructed a national portrait of older adult daters. Roughly 14% of singles were in a dating relationship. Dating was more common among men than women and declined with age. Compared to non-daters, daters were more socially advantaged. Daters were more likely to be college educated and had more assets, were in better health, and reported more social connectedness. This study underscores the importance of new research on partnering in later life, particularly with the aging of the U.S. population and the swelling ranks of older singles. PMID:24319296

  4. Relative Dating Via Fractures

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    This VIS image of the eastern part of the Tharsis region illustrates how fractures can be used in relative dating of a surface. The fractured materials on the right side of the image are embayed by younger volcanic flows originating to the west of the image. Note how the younger flows cover the ends of the fractures, and are not at all fractured themselves.

    Image information: VIS instrument. Latitude 43.2, Longitude 269.4 East (90.6 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  5. Live 129I-129Xe dating

    NASA Technical Reports Server (NTRS)

    Marti, K.

    1986-01-01

    A technique of cosmic ray exposure age dating using cosmic ray produced I-129 and Xe-129 components is discussed. The live I-129 - Xe-129 method provides an ideal monitor for cosmic ray flux variations on the 10(7)y - 10(8)y time-scale. It is based on low-energy neutron reactions on Te, and these data, when coupled to those from other methods, may facilitate the detection of complex exposure histories.

  6. A Simple Example of Radioactive Dating

    ERIC Educational Resources Information Center

    Brown, Todd

    2014-01-01

    Although nuclear half-life is vital to physics and physical science, and to sensitive societal issues from nuclear waste to the age of the Earth, a true lab on half-life is almost never done at the college or high school level. Seldom are students able to use radioactivity to actually date when an object came into being, as is done in this…

  7. Two 1999 Dates Worth Noting

    NASA Technical Reports Server (NTRS)

    Stern, David P.

    1999-01-01

    Two dates in 1999 can serve as pivots for space-related educational outreach. On August 11 a total solar eclipse will sweep across Europe and also across the Near East, where it will come remarkably close to matching the ancient eclipse (probably in 129 BC) used by Hipparchus to estimate the distance of the Moon. Using published eclipse data, students may conduct a similar calculation for 1999 and in the process obtain insights about astronomy, history and the way scientists work. October 19, 1999 will be the 100th anniversary of the day when a teen-age Robert Goddard climbed a cherry tree near the Worcester home where his family was staying, intending to prune it. Sitting in that tree, Goddard began daydreaming about space flight, and by the time he came down he had resolved to dedicate his life to implementing that dream. He later marked that day as "Anniversary day," a personal holiday. Material on both subjects can be reached from http://www-spof.gsfc.nasa.gov/stargaze/Sintro.htm, sections 8a and 26. The section on Goddard includes his experiments with a ballistic pendulum and the DeLaval nozzle, which laid the essential scientific foundation of spaceflight and which is also suitable for classroom presentation.

  8. The Influence of Dating Anxiety on Normative Experiences of Dating, Sexual Interactions, and Alcohol Consumption among Canadian Middle Adolescents

    ERIC Educational Resources Information Center

    Boyle, Andrea M.; O'Sullivan, Lucia F.

    2013-01-01

    Adolescents tend to consume alcohol and find romantic and sexual partners in mixed-group settings that are unmonitored by adults. Relatively little is known about the influence that dating anxiety may have with these social interactions. A sample of 163 high school students (aged 14-17 years) completed online surveys assessing dating, sex, and…

  9. Drinking and Dating: Examining the Link among Relationship Satisfaction, Hazardous Drinking, and Readiness-to-Change in College Dating Relationships

    ERIC Educational Resources Information Center

    Khaddouma, Alexander; Shorey, Ryan C.; Brasfield, Hope; Febres, Jeniimarie; Zapor, Heather; Elmquist, Joanna; Stuart, Gregory L.

    2016-01-01

    For this study we examined the association between relationship satisfaction and readiness-to-change alcohol use, as well as the associations between hazardous drinking and readiness-to-change relationship issues in college dating relationships. A sample of 219 college students in a current dating relationship (aged 18-25) completed self-report…

  10. Age dating ground water by use of chlorofluorocarbons (CCl{sub 3}F and CCl{sub 2}F{sub 2}), and distribution of chlorofluorocarbons in the unsaturated zone, Snake River Plain aquifer, Idaho National Engineering Laboratory, Idaho

    SciTech Connect

    Busenberg, E.; Weeks, E.P.; Plummer, L.N.; Bartholomay, R.C.

    1993-04-01

    Detectable concentrations of chlorofluorocarbons (CFC`s) were observed in ground water and unsaturated-zone air at the Idaho National Engineering Laboratory (INEL) and vicinity. The recharge ages of waters were determined to be from 4 to more than 50 years on the basis of CFC concentrations and other environmental data; most ground waters have ages of 14 to 30 years. These results indicate that young ground water was added at various locations to the older regional ground water (greater than 50 years) within and outside the INEL boundaries. The wells drilled into the Snake River Plain aquifer at INEL sampled mainly this local recharge. The Big Lost River, Birch Creek, the Little Lost River, and the Mud Lake-Terreton area appear to be major sources of recharge of the Snake River Plain aquifer at INEL. An average recharge temperature of 9.7{plus_minus}1.3{degrees}C (degrees Celsius) was calculated from dissolved nitrogen and argon concentrations in the ground waters, a temperature that is similar to the mean annual soil temperature of 9{degrees}C measured at INEL. This similarity indicates that the aquifer was recharged at INEL and not at higher elevations that would have cooler soil temperatures than INEL. Soil-gas concentrations at Test Area North (TAN) are explained by diffusion theory.

  11. The volcano-sedimentary evolution of a post-Variscan intramontane basin in the Swiss Alps (Glarus Verrucano) as revealed by zircon U-Pb age dating and Hf isotope geochemistry

    NASA Astrophysics Data System (ADS)

    Letsch, Dominik; Winkler, Wilfried; von Quadt, Albrecht; Gallhofer, Daniela

    2015-01-01

    The Late Palaeozoic Glarus Verrucano basin (GVB, Glarus Alps, eastern Switzerland) formed as an intramontane graben in the aftermath of the Variscan orogeny. Its fill, the Glarus Verrucano, consists of immature alluvial fan and playa lake deposits with intercalated bimodal volcanics (basalts and rhyolites). Despite its importance for local and regional geology, no modern sedimentologic or stratigraphic studies on the GVB exist. By means of sedimentologic and geochronologic studies, we reconstruct the volcano-sedimentary evolution of the GVB: it developed at the Carboniferous/Permian boundary and experienced a first (bimodal) volcanic phase around 285 Ma. For the same time, indications for temporarily humid climate in the otherwise rather arid Early Permian are demonstrated (e.g. pyrite-bearing sandstones). During the Middle and Early Late Permian, increasing aridity is indicated by playa deposits, fanglomerates and subaerial ignimbrites, which mark a second (silicic) volcanic phase at 268 Ma. The detrital zircon age spectra are dominated by Late Variscan ages and thus demonstrate that older sedimentary and metamorphic rocks once forming the Variscan nappe edifice were already mostly eroded at that time. Finally, some larger-scale speculations are given which could indicate a causal connection between the widespread tectono-magmatic Mid-Permian Episode and the local development of the Glarus Verrucano basin.

  12. Longitudinal dating violence victimization among Latino teens: Rates, risk factors, and cultural influences.

    PubMed

    Sabina, Chiara; Cuevas, Carlos A; Cotignola-Pickens, Heather M

    2016-02-01

    This study uses data from two waves of the Dating Violence Among Latino Adolescents (DAVILA) study and focuses on the 1) rates of dating violence victimization by gender, 2) risk of experiencing dating violence victimization over time, 3) association of dating violence victimization with other forms of victimization, and 4) association of immigrant status, acculturation, and familial support with dating violence victimization over time. A total of 547 Latino adolescents, from across the USA, aged 12-18 at Wave 1 participated in both waves of the study. Rates of dating violence were around 19% across waves. Dating violence at Wave 1 and non-dating violence victimization were associated with an elevated risk of dating violence during Wave 2. Cultural factors did not distinguish between dating violence trajectories, except for immigrant status and familial support being associated with no dating violence victimization. Overall, dating violence affects a large number of Latino teens and tends to continue over time.

  13. Dating loess up to 800 ka by thermoluminescence

    SciTech Connect

    Berger, G.W. ); Pillans, B.J. ); Palmer, A.S. )

    1992-05-01

    Thermoluminescence (TL) ages agreeing with expected ages have been obtained for 13 loess samples spanning the age range from 20 to 800 ka. The authors samples are from Alaska and North Island, New Zealand, and are unusual in TL dating studies of loess older than 80-100 ka by having independent age assignments that are generally well constrained, from ages of associated tephra beds. With the polymineral fine-silt-sized (4-11 {mu}m) grains the partial-bleach TL technique yielded expected ages up to about 350 ka, whereas the total-bleach method gave accurate ages in the range 100 to 800 ka. Thus, the much disputed upper age limit of 100-150 ka for the TL dating of loess now appears to be sample and worker dependent, rather than a global property of the TL signals in the TL-dominant feldspars.

  14. White Asparagus Harvest Date Discrimination Using Nirs Technology

    NASA Astrophysics Data System (ADS)

    Jarén, C.; Arazuri, S.; García, M. J.; Arnal, P.; Arana, J. I.

    2006-03-01

    Asparagus is still an important resource for mid-size and small farms. It has been traditionally believed that factors such as the asparagus harvesting date have an influence on its quality. This research sought to identify the harvesting dates of different fruits by using Near Infrared Spectroscopy (NIRS) technology as quality indicators and the best zone a long of the asparagus to acquire the spectrum. All the asparagus tested came from the same manufacturer but had been canned on three different dates, giving a total of nine lots. There were one hundred asparagus per lot and the experiment data were taken from three different parts (tip, middle, and base) of each spear. Reflectance spectrum in the near infrared between 800 1700 nm was determined. Differences NIRS among the asparagus harvested on different dates were found. NIRS technology was able to classify the asparagus correctly in terms of harvest dates (71% well classified). The base of the asparagus turned out to be the best part to use in order to establish the harvest date.

  15. Dating a tropical ice core by time-frequency analysis of ion concentration depth profiles

    NASA Astrophysics Data System (ADS)

    Gay, M.; De Angelis, M.; Lacoume, J.-L.

    2014-09-01

    Ice core dating is a key parameter for the interpretation of the ice archives. However, the relationship between ice depth and ice age generally cannot be easily established and requires the combination of numerous investigations and/or modelling efforts. This paper presents a new approach to ice core dating based on time-frequency analysis of chemical profiles at a site where seasonal patterns may be significantly distorted by sporadic events of regional importance, specifically at the summit area of Nevado Illimani (6350 m a.s.l.), located in the eastern Bolivian Andes (16°37' S, 67°46' W). We used ion concentration depth profiles collected along a 100 m deep ice core. The results of Fourier time-frequency and wavelet transforms were first compared. Both methods were applied to a nitrate concentration depth profile. The resulting chronologies were checked by comparison with the multi-proxy year-by-year dating published by de Angelis et al. (2003) and with volcanic tie points. With this first experiment, we demonstrated the efficiency of Fourier time-frequency analysis when tracking the nitrate natural variability. In addition, we were able to show spectrum aliasing due to under-sampling below 70 m. In this article, we propose a method of de-aliasing which significantly improves the core dating in comparison with annual layer manual counting. Fourier time-frequency analysis was applied to concentration depth profiles of seven other ions, providing information on the suitability of each of them for the dating of tropical Andean ice cores.

  16. Test Review: Autism Spectrum Rating Scales

    ERIC Educational Resources Information Center

    Simek, Amber N.; Wahlberg, Andrea C.

    2011-01-01

    This article reviews Autism Spectrum Rating Scales (ASRS) which are designed to measure behaviors in children between the ages of 2 and 18 that are associated with disorders on the autism spectrum as rated by parents/caregivers and/or teachers. The rating scales include items related to behaviors associated with Autism, Asperger's Disorder, and…

  17. Violence exposure and teen dating violence among African American youth.

    PubMed

    Black, Beverly M; Chido, Lisa M; Preble, Kathleen M; Weisz, Arlene N; Yoon, Jina S; Delaney-Black, Virginia; Kernsmith, Poco; Lewandowski, Linda

    2015-07-01

    This study examines the relationships between exposure to violence in the community, school, and family with dating violence attitudes and behaviors among 175 urban African American youth. Age, gender, state support and experiences with neglect, school violence, and community violence were the most significant predictors of acceptance of dating violence. Experiences with community violence and age were important predictors of dating violence perpetration and victimization. Findings highlight the importance of planning prevention programs that address variables affecting attitudes and behaviors of high-risk youth who have already been exposed to multiple types of violence.

  18. VIEW OF DATE DRIVE, SHOWING DATE PALMS. NOTE TRELLIS ON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF DATE DRIVE, SHOWING DATE PALMS. NOTE TRELLIS ON TYPE 11 FACILITY, FACILITY 808. VIEW FACING NORTHWEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  19. Resolving the age of the first-order topography of southern Africa: new insight from joint (U-Th)/He and fission track dating of samples from deep boreholes

    NASA Astrophysics Data System (ADS)

    Beucher, R.; Brown, R. W.; Persano, C.; Stuart, F.; Gallagher, K.

    2011-12-01

    The topography of Africa is unusually high with respect to other continents and its origin remains strongly debated. Africa's topography is strongly bimodal as it is distributed between the high plateau areas in its central part (circa 1000 m), and significantly less elevated areas with higher relief around its borders. The geodynamical interpretation of this feature is not straightforward as the plateau is essentially surrounded by passive margins and oceanic ridges. However, abundant seismic studies have revealed a deep seismic anomaly beneath Africa and suggest that forces related to active upward flow within the mantle are dynamically sustaining its high elevation. If the large anomaly provides a mechanism explaining the south African plateau, a lot of questions remain on the timing of uplift. Geodynamic models allow Africa to go up or down but fail to put constrains on the age of the uplift. This is mainly because of a lack of tight constraints on the viscosity and density structure of the mantle, which lead to several models with uplift occurring either during Cretaceous or Miocene times. The question of the age of the plateau therefore remains unresolved. Thermochronology and techniques such as fission track and U-Th/He analyses provide tools to address this question by constraining the erosion history. In this study we take advantage of the availability of deep boreholes located all across south-Africa to sample truly vertical profiles through the plateau. The key advantage of this approach is that it enables constraints to be placed on the timing and amount of cooling resulting from relatively low amounts of erosion. A dozen boreholes from above and below the great escarpment have been sampled. We present fission track and U-Th/He results for three of them. The U-Th/He analyses are performed as single grain analyses with an average number of 15+ aliquots per sample for a total of 250+ single grain analyses in order to provide a high resolution chronology

  20. 40Ar-39Ar dating of volcanogenic products from the AND-2A core (ANDRILL Southern McMurdo Sound Project, Antarctica): correlations with the Erebus Volcanic Province and implications for the age model of the core

    NASA Astrophysics Data System (ADS)

    di Vincenzo, Gianfranco; Bracciali, Laura; Del Carlo, Paola; Panter, Kurt; Rocchi, Sergio

    2010-05-01

    The AND-2A drillcore (Antarctic Drilling Program—ANDRILL) was successfully completed in late 2007 on the Antarctic continental margin (Southern McMurdo Sound, Ross Sea) with the aim of tracking ice proximal to shallow marine environmental fluctuations and to document the 20-Ma evolution of the Erebus Volcanic Province. Lava clasts and tephra layers from the AND-2A drillcore were investigated from a petrographic and stratigraphic point of view and analyzed by the 40Ar-39Ar laser technique in order to constrain the age model of the core and to gain information on the style and nature of sediment deposition in the Victoria Land Basin since Early Miocene. Ten out of 17 samples yielded statistically robust 40Ar-39Ar ages, indicating that the AND-2A drillcore recovered ≤230 m of Middle Miocene (˜128-358 m below sea floor, ˜11.5-16.0 Ma) and >780 m of Early Miocene (˜358-1093 m below sea floor, ˜16.0-20.1 Ma). Results also highlight a nearly continuous stratigraphic record from at least 358 m below sea floor down hole, characterized by a mean sedimentation rate of ˜19 cm/ka, possible oscillations of no more than a few hundreds of ka and a break within ˜17.5-18.1 Ma. Comparison with available data from volcanic deposits on land, suggests that volcanic rocks within the AND-2A core were supplied from the south, possibly with source areas closer to the drill site for the upper core levels, and from 358 m below sea floor down hole, with the “proto-Mount Morning” as the main source.