2,353 research outputs found

    Bottom waters of the Gulf of Maine, 1978-1983

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    The properties of the bottom waters (\u3e100 m) of the Gulf of Maine are described using hydrographic data from 26 surveys between May 1978 and December 1983. The average temperature and salinity of the bottom water are presented from the different surveys for four regions of the Gulfβ€”Wilkinson, Jordan, and Georges Basins and the Northeast Channel. The spatial variability across the Gulf was larger than the temporal variability in any region. The bottom water originates from Slope Water that enters the Gulf through the Northeast Channel. It is modified within the Gulf by vertical mixing with the near-surface waters of Scotian Shelf origin. A box model for the property changes during the summer-fall period indicates that the advection and mixing processes are of approximately equal importance in determining the bottom water properties. A winter convective input to the bottom layers is shown to occur only from the coastal areas around Wilkinson Basin in years when the surface salinity there was relatively high (\u3e33.0‰). Advection and mixing rates calculated by the box model are in agreement with direct measurements of the inflow to the Gulf (Ramp et al., 1985) and mixing estimates from a budget for the intermediate layer waters in the Gulf (Hopkins and Garfield, 1979)

    Genome-wide analysis points to roles for extracellular matrix remodeling, the visual cycle, and neuronal development in myopia

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    Myopia, or nearsightedness, is the most common eye disorder, resulting primarily from excess elongation of the eye. The etiology of myopia, although known to be complex, is poorly understood. Here we report the largest ever genome-wide association study (43,360 participants) on myopia in Europeans. We performed a survival analysis on age of myopia onset and identified 19 significant associations (p < 5e-8), two of which are replications of earlier associations with refractive error. These 19 associations in total explain 2.7% of the variance in myopia age of onset, and point towards a number of different mechanisms behind the development of myopia. One association is in the gene PRSS56, which has previously been linked to abnormally small eyes; one is in a gene that forms part of the extracellular matrix (LAMA2); two are in or near genes involved in the regeneration of 11-cis-retinal (RGR and RDH5); two are near genes known to be involved in the growth and guidance of retinal ganglion cells (ZIC2, SFRP1); and five are in or near genes involved in neuronal signaling or development. These novel findings point towards multiple genetic factors involved in the development of myopia and suggest that complex interactions between extracellular matrix remodeling, neuronal development, and visual signals from the retina may underlie the development of myopia in humans

    Systematic review of predictive performance of injury severity scoring tools

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    Many injury severity scoring tools have been developed over the past few decades. These tools include the Injury Severity Score (ISS), New ISS (NISS), Trauma and Injury Severity Score (TRISS) and International Classification of Diseases (ICD)-based Injury Severity Score (ICISS). Although many studies have endeavored to determine the ability of these tools to predict the mortality of injured patients, their results have been inconsistent. We conducted a systematic review to summarize the predictive performances of these tools and explore the heterogeneity among studies. We defined a relevant article as any research article that reported the area under the Receiver Operating Characteristic curve as a measure of predictive performance. We conducted an online search using MEDLINE and Embase. We evaluated the quality of each relevant article using a quality assessment questionnaire consisting of 10 questions. The total number of positive answers was reported as the quality score of the study. Meta-analysis was not performed due to the heterogeneity among studies. We identified 64 relevant articles with 157 AUROCs of the tools. The median number of positive answers to the questionnaire was 5, ranging from 2 to 8. Less than half of the relevant studies reported the version of the Abbreviated Injury Scale (AIS) and/or ICD (37.5%). The heterogeneity among the studies could be observed in a broad distribution of crude mortality rates of study data, ranging from 1% to 38%. The NISS was mostly reported to perform better than the ISS when predicting the mortality of blunt trauma patients. The relative performance of the ICSS against the AIS-based tools was inconclusive because of the scarcity of studies. The performance of the ICISS appeared to be unstable because the performance could be altered by the type of formula and survival risk ratios used. In conclusion, high-quality studies were limited. The NISS might perform better in the mortality prediction of blunt injuries than the ISS. Additional studies are required to standardize the derivation of the ICISS and determine the relative performance of the ICISS against the AIS-based tools

    Systematic review of predictive performance of injury severity scoring tools

    Get PDF
    Many injury severity scoring tools have been developed over the past few decades. These tools include the Injury Severity Score (ISS), New ISS (NISS), Trauma and Injury Severity Score (TRISS) and International Classification of Diseases (ICD)-based Injury Severity Score (ICISS). Although many studies have endeavored to determine the ability of these tools to predict the mortality of injured patients, their results have been inconsistent. We conducted a systematic review to summarize the predictive performances of these tools and explore the heterogeneity among studies. We defined a relevant article as any research article that reported the area under the Receiver Operating Characteristic curve as a measure of predictive performance. We conducted an online search using MEDLINE and Embase. We evaluated the quality of each relevant article using a quality assessment questionnaire consisting of 10 questions. The total number of positive answers was reported as the quality score of the study. Meta-analysis was not performed due to the heterogeneity among studies. We identified 64 relevant articles with 157 AUROCs of the tools. The median number of positive answers to the questionnaire was 5, ranging from 2 to 8. Less than half of the relevant studies reported the version of the Abbreviated Injury Scale (AIS) and/or ICD (37.5%). The heterogeneity among the studies could be observed in a broad distribution of crude mortality rates of study data, ranging from 1% to 38%. The NISS was mostly reported to perform better than the ISS when predicting the mortality of blunt trauma patients. The relative performance of the ICSS against the AIS-based tools was inconclusive because of the scarcity of studies. The performance of the ICISS appeared to be unstable because the performance could be altered by the type of formula and survival risk ratios used. In conclusion, high-quality studies were limited. The NISS might perform better in the mortality prediction of blunt injuries than the ISS. Additional studies are required to standardize the derivation of the ICISS and determine the relative performance of the ICISS against the AIS-based tools

    Advances in Marine Ecosystem Dynamics from US GLOBEC: The Horizontal-Advection Bottom-up Forcing Paradigm

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    A primary focus of the US Global Ocean Ecosystem Dynamics (GLOBEC) program was to identify the mechanisms of ecosystem response to large- scale climate forcing under the assumption that bottom-up forcing controls a large fraction of marine ecosystem variability. At the beginning of GLOBEC, the prevailing bottom-up forcing hypothesis was that climate-induced changes in vertical transport modulated nutrient supply and surface primary productivity, which in turn affected the lower trophic levels (e.g., zooplankton) and higher trophic levels (e.g., fish) through the trophic cascade. Although upwelling dynamics were confirmed to be an important driver of ecosystem variability in GLOBEC studies, the use of eddy- resolving regional-scale ocean circulation models combined with field observations revealed that horizontal advection is an equally important driver of marine ecosystem variability. Trough a synthesis of studies from the four US GLOBEC regions (Gulf of Alaska, Northern California Current, Northwest Atlantic, and Southern Ocean), a new horizontal-advection bottom-up forcing paradigm emerges in which large-scale climate forcing drives regional changes in alongshore and cross-shelf ocean transport that directly impact ecosystem functions (e.g., productivity, species composition, spatial connectivity). Te horizontal advection bottom-up forcing paradigm expands the mechanistic pathways through which climate variability and climate change impact the marine ecosystem. In particular, these results highlight the need for future studies to resolve and understand the role of mesoscale and submesoscale transport processes and their relationship to climate

    The Genetic Ancestry of African Americans, Latinos, and European Americans Across the United States

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    Over the past 500 years, North America has been the site of ongoing mixing of Native Americans, European settlers, and Africans (brought largely by the trans-Atlantic slave trade), shaping the early history of what became the United States. We studied the genetic ancestry of 5,269 self-described African Americans, 8,663 Latinos, and 148,789 European Americans who are 23andMe customers and show that the legacy of these historical interactions is visible in the genetic ancestry of present-day Americans. We document pervasive mixed ancestry and asymmetrical male and female ancestry contributions in all groups studied. We show that regional ancestry differences reflect historical events, such as early Spanish colonization, waves of immigration from many regions of Europe, and forced relocation of Native Americans within the US. This study sheds light on the fine-scale differences in ancestry within and across the United States and informs our understanding of the relationship between racial and ethnic identities and genetic ancestry

    Influence of ocean freshening on shelf phytoplankton dynamics

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    Author Posting. Β© American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 34 (2007): L24607, doi:10.1029/2007GL032010.Climate change-induced freshening of the ocean can enhance vertical stratification and alter circulation patterns in ways that influence phytoplankton dynamics. We examined the timing of spring phytoplankton blooms and the magnitude of net primary productivity in the Nova Scotian Shelf (NSS) - Gulf of Maine (GoM) region with respect to seasonal and interannual changes in surface water freshening from 1998 to 2006. The general pattern of temporal westward progression of the phytoplankton bloom corresponds with the gradient of increasing sea surface salinity from the NSS in the east to the western GoM. Increased freshening enhances the spatial gradients in bloom timing by stimulating earlier blooms upstream (NSS), but it has less impact downstream (the western GoM). Strong spatial gradients (increasing westward) of mean chlorophyll concentration and net primary productivity during post-bloom months (May–June) indicate that lower sea surface salinity upstream can likely impede nutrient fluxes from deep water and therefore affect overall productivity.We thank NSF grant OCE-0727033 and NOAA grant NA17RJ1223 to RJ, CSD and RCB, NSF grants OCE- 0606612 and OCE-0726577 to DWT, and NSF grants OCE-0606928 and OCE-0726851 to CC
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