1,449 research outputs found

    A new early Silurian prioniodontid conodont with three P elements from Iran and associated species

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    Copyright © 2015 P. MÀnnik et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article

    Biostratigraphic utility of coiling direction in Miocene planktonic foraminiferal genus Paragloborotalia

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    Trochospiral planktonic foraminifera will coil either sinistral (left) or dextral (right). The prevalence of sinistral or dextral coiling can change through the stratigraphic range of morphospecies with a preference in coiling direction. A number of coiling shifts have been applied as secondary marker events through the Recent to late Miocene (~0–7 Ma) biochronology. However, no such events have been applied beyond this age despite a number of species being known to adopt preferential coiling directions. Here we investigate selected Miocene species within the genus Paragloborotalia. Previous work in the tropical to subtropical realm has shown that the mayeri–siakensis group undergoes a shift from random to sinistrally dominated coiling in the mid Miocene (~15 Ma). We extend the investigation to other Miocene paragloborotaliids in the low (IODP Sites U1337, U1338, ODP Sites 871 and 925), mid (JOIDES-3 hole) and high latitudes (ODP Site 747) in order to assess whether there is global synchronicity and if the change is unique to the mayeri-siakensis group. In addition, a number of outcrop samples from the Cipero and Lengua formations in southern Trinidad are quantitatively compared to previously published trends. Our results show that in the low-mid latitudes the coiling shift is at ~15.37 Ma within planktonic foraminiferal Zone M5 within both Paragloborotalia siakensis and Paragloborotalia continuosa. In the high latitudes the absence of paragloborotaliids through a portion of the mid Miocene interval prevents accurate dating of a shift from early forms showing random coiling to later paragloborotaliids adopting a sinistral preference. We also find two coiling changes in the genus Globorotalia at high latitude Site 747, from random to sinistral in the mid Miocene (15.14 Ma) and sinistral to dextral (10.02 Ma) in the late Miocene. We propose the recognition of a coiling change in Paragloborotalia as a secondary bioevent in the mid Miocene at 15.37 Ma, and a useful means for the recognition of the base of the Langhian. The coiling shift as a biostratigraphic marker is likely to be particularly useful in regions where the currently applied bioevents, namely the Praeorbulina–Orbulina lineage, is rare or poorly represented

    Quantifying the effect of anthropogenic climate change on calcifying plankton

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    Widely regarded as an imminent threat to our oceans, ocean acidification has been documented in all oceanic basins. Projected changes in seawater chemistry will have catastrophic biotic effects due to ocean acidification hindering biogenic carbonate production, which will in turn lead to substantial changes in marine ecosystems. However, previous attempts to quantify the effect of acidification on planktonic calcifying organisms has relied on laboratory based studies with substantial methodological limitations. This has been overcome by comparing historic plankton tows from the seminal HMS Challenger Expedition (1872-1876) with the recent Tara Oceans expedition material (2009-2016). Nano CT-scans of selected equatorial Pacific Ocean planktonic foraminifera, have revealed that all modern specimens had up to 76% thinner shells than their historic counterparts. The "Challenger Revisited" project highlights the potential of historic ocean collections as a tool to investigate ocean acidification since the early Industrial Revolution. Further analyses of such biotic archives will enable researchers to quantify the effects of anthropogenic climate change across the globe

    Home versus day rehabilitation: a randomised controlled trial

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    Objective: to assess the effect of home versus day rehabilitation on patient outcomes

    The unknown planktonic foraminiferal pioneer Henry A. Buckley and his collection at The Natural History Museum, London

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    © 2017 The Author(s) This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/). The version attached is the published pdf

    Bioelectrical phase angle values in a clinical sample of ambulatory rehabilitation patients

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    Background: Phase angle (PhA) is derived from the resistance and reactance measurements obtained from bioelectric impedance analysis (BIA) and is considered indicative of cellular health and membrane integrity. This study measured PhA values of rehabilitation patients and compared them to reference values, measures of functional ability and serum C-reactive protein (CRP) levels to explore their utility as a clinical tool to monitor disease progression and treatment efficacy. Methods: This cross-sectional observational study was conducted on 215 ambulatory rehabilitation patients aged 20 – 94 years. All participants had been hospitalised for a stroke, orthopaedic or other condition resulting in a functional limitation. PhA was derived from BIA analysis and functional ability characterised using the Functional Independence Measure (FIM), timed up and go (TUG) and maximal quadriceps strength (MQS). Serum levels of CRP were also collected. Results: Stroke patients had the highest PhA (5.3°) followed by elective orthopaedic surgery (5.0°) with the other group (4.3°) significantly lower than both previous categories (p < 0.001). Ambulatory rehabilitation patients' PhA values were dependent on age and sex (p < 0.001), lower than published age matched healthy reference values (p ≀ 0.05) and similar to other hospitalised or sick groups, but also higher than values reported in critically ill patients. Patients with CRP values less than 10 mg.L-1 had significantly (p = 0.005) higher mean PhA values. Furthermore, the highest functional status quartiles had significantly higher PhAs (p ≀ 0.04) for the FIM, MQS and TUG measures. Conclusion: The results suggest that the phase angles of rehabilitation patients are between those of healthy individuals and seriously ill patients, thereby supporting claims that PhA is indicative of general health status. Phase angles are a potentially useful indicator of functional status in patients commencing an ambulatory rehabilitation program with a normal hydration status.Simon M. Gunn, Julie A. Halbert, Lynne C. Giles, Jacqueline M. Stepien, Michelle D. Miller and Maria Crott

    Surface Sediment Samples From Early Age of Seafloor Exploration Can Provide a Late 19th Century Baseline of the Marine Environment

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    Ocean-floor sediment samples collected up to 150 years ago represent an important historical archive to benchmark global changes in the seafloor environment, such as species' range shifts and pollution trends. Such benchmarking requires that the historical sediment samples represent the state of the environment at—or shortly before the time of collection. However, early oceanographic expeditions sampled the ocean floor using devices like the sounding tube or a dredge, which potentially disturb the sediment surface and recover a mix of Holocene (surface) and deeper, Pleistocene sediments. Here we use climate-sensitive microfossils as a fast biometric method to assess if historical seafloor samples contain a mixture of modern and glacial sediments. Our assessment is based on comparing the composition of planktonic foraminifera (PF) assemblages in historical samples with Holocene and Last Glacial Maximum (LGM) global reference datasets. We show that eight out of the nine historical samples contain PF assemblages more similar to the Holocene than to the LGM PF assemblages, but the comparisons are only significant when there is a high local species' temporal turnover (from the LGM to the Holocene). When analysing temporal turnover globally, we show that upwelling and temperate regions had greatest species turnover, which are areas where our methodology would be most diagnostic. Our results suggest that sediment samples from historical collections can provide a baseline of the state of marine ecosystems in the late nineteenth century, and thus be used to assess ocean global change trends
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