18,622 research outputs found

    Assessing urinary flow rate, creatinine, osmolality and other hydration adjustment methods for urinary biomonitoring using NHANES arsenic, iodine, lead and cadmium data

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    Background There are numerous methods for adjusting measured concentrations of urinary biomarkers for hydration variation. Few studies use objective criteria to quantify the relative performance of these methods. Our aim was to compare the performance of existing methods for adjusting urinary biomarkers for hydration variation. Methods Creatinine, osmolality, excretion rate (ER), bodyweight adjusted ER (ERBW) and empirical analyte-specific urinary flow rate (UFR) adjustment methods on spot urinary concentrations of lead (Pb), cadmium (Cd), non-arsenobetaine arsenic (AsIMM) and iodine (I) from the US National Health and Nutrition Examination Survey (NHANES) (2009–2010 and 2011–2012) were evaluated. The data were divided into a training dataset (n = 1,723) from which empirical adjustment coefficients were derived and a testing dataset (n = 428) on which quantification of the performance of the adjustment methods was done by calculating, primarily, the correlation of the adjusted parameter with UFR, with lower correlations indicating better performance and, secondarily, the correlation of the adjusted parameters with blood analyte concentrations (Pb and Cd), with higher correlations indicating better performance. Results Overall performance across analytes was better for Osmolality and UFR based methods. Excretion rate and ERBW consistently performed worse, often no better than unadjusted concentrations. Conclusions Osmolality adjustment of urinary biomonitoring data provides for more robust adjustment than either creatinine based or ER or ERBW methods, the latter two of which tend to overcompensate for UFR. Modified UFR methods perform significantly better than all but osmolality in removing hydration variation, but depend on the accuracy of UFR calculations. Hydration adjustment performance is analyte-specific and further research is needed to establish a robust and consistent framework

    The arrangement of possible muscle fibres in the Ediacaran taxon <i>Haootia quadriformis</i>

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    Haootia quadriformis from Newfoundland, Canada, is one of the most unusual impressions of a soft-bodied macro-organism yet described from the late Ediacaran Period. Interpreted as a metazoan of cnidarian grade, the body impression of H. quadriformis possesses features interpreted as fibrous structures that represent possible evidence for muscular tissue. Evidence both in support of and against a relationship between H. quadriformis and the Staurozoa, one of the cnidarian groups to which Haootia was compared in Liu et al., is outlined by Miranda et al.. Our intention in our original paper was to illustrate the staurozoan body plan for comparative purposes, rather than suggest homology or direct ancestry. Nevertheless, fresh insights from workers with expertise in the biology of extant cnidarians are welcomed

    Earth science education in South Australia: Evolving with the resources boom

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    Copyright © 2007 AusIMM The document attached has been archived with permission from the publisher.Andreas Schmidt Mumm MAusIMM and Alan Collins, Geology and Geophysics, School of Earth and Environmental Sciences, The University of Adelaidehttp://direct.bl.uk/bld/PlaceOrder.do?UIN=206473720&ETOC=RN&from=searchengin

    Magnetotelluric experiments in Central and Southern Australia and their implications for tectonic evolution

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    Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, Discipline of Geology and Geophysics, 200

    Systematics of hydrophiine brown snakes (Pseudonaja)

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    This thesis reviews the species level systematics of Pseudonaja, a group of medically important hydrophiine snakes, commonly called brown snakes.Thesis (M.Sc.) -- University of Adelaide, School of Earth and Environmental Sciences, 200

    Journal of Maps

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    Journal of Maps (JoM) (http://www.journalofmaps.com) počeo je izlaziti 2005. godine isključivo kao elektronički časopis. Izdavač je School of Earth Sciences and Geography, Kingston University, UK. Budući da ne izlazi u tiskanom izdanju, časopis nema uobičajene sveske. Svescima se, ipak, mogu smatrati članci srodne tematike koji se objavljuju tri puta godiơnje – u travnju, kolovozu i prosincu

    The Great Oxidation Event preceded a Paleoproterozoic “snowball Earth”

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    The inability to resolve the exact temporal relationship between two pivotal events in Earth history, the Paleoproterozoic Great Oxidation Event (GOE) and the first “snowball Earth” global glaciation, has precluded assessing causality between changing atmospheric composition and ancient climate change. Here we present temporally resolved quadruple sulfur isotope measurements (ÎŽ34S, ∆33S, and ∆36S) from the Paleoproterozoic Seidorechka and Polisarka Sedimentary Formations on the Fennoscandian Shield, northwest Russia, that address this issue. Sulfides in the former preserve evidence of mass-independent fractionation of sulfur isotopes (S-MIF) falling within uncertainty of the Archean reference array with a ∆36S/∆33S slope of −1.8 and have small negative ∆33S values, whereas in the latter mass-dependent fractionation of sulfur isotopes (S-MDF) is evident, with a ∆36S/∆33S slope of −8.8. These trends, combined with geochronological constraints, place the S-MIF/S-MDF transition, the key indicator of the GOE, between 2,501.5 ± 1.7 Ma and 2,434 ± 6.6 Ma. These are the tightest temporal and stratigraphic constraints yet for the S-MIF/S-MDF transition and show that its timing in Fennoscandia is consistent with the S-MIF/S-MDF transition in North America and South Africa. Further, the glacigenic part of the Polisarka Formation occurs 60 m above the sedimentary succession containing S-MDF signals. Hence, our findings confirm unambiguously that the S-MIF/S-MDF transition preceded the Paleoproterozoic snowball Earth. Resolution of this temporal relationship constrains cause-and-effect drivers of Earth’s oxygenation, specifically ruling out conceptual models in which global glaciation precedes or causes the evolution of oxygenic photosynthesis

    Transformation-cost time-series method for analyzing irregularly sampled data

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    ACKNOWLEDGEMENTS We thank K.-H. Wyrwoll and F. McRobie from the School of Earth and Environment (UWA) for fruitful discussions. Moreover, we acknowledge for financial supports from TUBITAK under the 2214/A program (I.O.), from the Leibniz Association (WGL) under Grant No. SAW-2013-IZW-2542 (D.E.), as well as from the BMBF within the Potsdam Research Cluster for Georisk Analysis, Environmental Change and Sustainability (PROGRESS) Support Code No. 03IS2191B (N.M.).Peer reviewedPublisher PD

    Glaciology, geomorphology giant Roger Hooke passes away at 82

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    Roger Hooke, beloved University of Maine mentor and researcher and giant in the fields of glaciology and geomorphology, died March 10 [2021] at the age of 82. Hooke joined the School of Earth and Climate Sciences and Climate Change Institute in 2000 as a research professor and adviser. One of Hooke\u27s interests during his time at UMaine involved examining what glacial landforms in Maine revealed about the Laurentide Ice Sheet

    Categorical versus geometric morphometric approaches to characterizing the evolution of morphological disparity in Osteostraci (Vertebrata, stem Gnathostomata)

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    Morphological variation (disparity) tends to be evaluated through two non-mutually exclusive approaches: (i) quantitatively, through geometric morphometrics, and (ii) in terms of discrete, ‘cladistic’, or categorical characters. Uncertainty over the comparability of these approaches diminishes the potential to obtain nomothetic insights into the evolution of morphological disparity, and the few benchmarking studies conducted so far show contrasting results. Here, we apply both approaches to characterising morphology in the stem-gnathostome vertebrate clade Osteostraci, in order to assess congruence between these alternative methods as well as to explore the evolutionary patterns of the group in terms of temporal disparity and the influence of phylogenetic relationships and habitat on morphospace occupation. Our results suggest that both approaches yield similar results in morphospace occupation and clustering, but also some differences indicating that these metrics may capture different aspects of morphology. Phylomorphospaces reveal important convergence towards a generalised ‘horseshoe’-shaped cranial morphology and two strong branching trends involving different major groups of osteostracans (benneviaspidids and thyestiids), which probably reflect adaptations to different lifestyles. Temporal patterns of disparity recorded by categorical and morphometric approaches differ considerably, capturing disparity maxima at very different times of the evolutionary history of the group. Disparity patterns recorded by the categorical approach parallel taxonomic diversity dynamics, likely reflecting a bias in facies representation rather than a real biological signal. This work provides evidence supporting that categorical and continuous data do not always capture morphological disparity in equivalent ways and that discrepancies reflect differences in the potential of each data type for characterizing more or less inclusive aspects of overall phenotype
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