233 research outputs found

    Teleporters, tunnels & time : Understanding warp devices in videogames

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    Catchment land uses, particularly agriculture and urban uses, have long been recognized as major drivers of nutrient concentrations in surface waters. However, few simple models have been developed that relate the amount of catchment land use to downstream freshwater nutrients. Nor are existing models applicable to large numbers of freshwaters across broad spatial extents such as regions or continents. This research aims to increase model performance by exploring three factors that affect the relationship between land use and downstream nutrients in freshwater: the spatial extent for measuring land use, hydrologic connectivity, and the regional differences in both the amount of nutrients and effects of land use on them. We quantified the effects of these three factors that relate land use to lake total phosphorus (TP) and total nitrogen (TN) in 346 north temperate lakes in 7 regions in Michigan, USA. We used a linear mixed modeling framework to examine the importance of spatial extent, lake hydrologic class, and region on models with individual lake nutrients as the response variable, and individual land use types as the predictor variables. Our modeling approach was chosen to avoid problems of multi-collinearity among predictor variables and a lack of independence of lakes within regions, both of which are common problems in broad-scale analyses of freshwaters. We found that all three factors influence land use-lake nutrient relationships. The strongest evidence was for the effect of lake hydrologic connectivity, followed by region, and finally, the spatial extent of land use measurements. Incorporating these three factors into relatively simple models of land use effects on lake nutrients should help to improve predictions and understanding of land use-lake nutrient interactions at broad scales

    The Case for Gun Policy Reforms in America

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    Debates about gun control often drift towards general arguments about whether guns make us safer or less safe, and gun control is equated with restricting gun ownership. However, with recent Supreme Court decisions overturning laws which ban firearm possession in the District of Columbia and Chicago, current gun control policies in the U.S. do not disarm lawabiding adults over the age of 21. Rather, gun control laws today focus on one or more of four general objectives. These laws aim to:Define conditions that prohibit a person from possessing firearms;Implement regulations to prevent prohibited persons from possessing firearms;Restrict carrying of concealed firearms outside the home; andRegulate the design of firearms to enhance public and personal safety.In this report we draw upon research evidence to suggest how improvements in each of these types of gun policies could enhance public safety in the United States

    3-D Photoionization Structure and Distances of Planetary Nebulae II. Menzel 1

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    We present the results of a spatio-kinematic study of the planetary nebula Menzel 1 using spectro-photometric mapping and a 3-D photoionization code. We create several 2-D emission line images from our long-slit spectra, and use these to derive the line fluxes for 15 lines, the Halpha/Hbeta extinction map, and the [SII] line ratio density map of the nebula. We use our photoionization code constrained by these data to derive the three-dimensional nebular structure and ionizing star parameters of Menzel 1 by simultaneously fitting the integrated line intensities, the density map, and the observed morphologies in several lines, as well as the velocity structure. Using theoretical evolutionary tracks of intermediate and low mass stars, we derive a mass for the central star of 0.63+-0.05 Msolar. We also derive a distance of 1050+_150 pc to Menzel 1.Comment: To be published in ApJ of 10th February 2005. 12 figure

    Tidal dynamics drive ooid formation in the Capricorn Channel since the Last Glacial Maximum

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    Relative sea-level changes can dramatically alter coastal geomorphology and coastlines, which, in turn, can fundamentally alter tidal regimes. The Great Barrier Reef (GBR) has undergone around 120 m of relative sea level (RSL) rise since the Last Glacial Maximum, ∼20,000 years ago (ka). Ooid grains (sand sized carbonate sediment) that formed in shallow water (>5 m depth) and under prolonged hydrodynamics forcing are now found at depth ranging between 100 and 120 m under the present day GBR Gulf of Capricorn. The apparent inconsistency between preferential conditions for their formation and the actual environment where they are found at present-day could be used to infer past regional hydrodynamic conditions. Here, we focus on the regional changes in the GBR tidal dynamics over the last 16.8 ka to show that sea-level rise on the GBR has caused significant changes on tidal patterns and dynamics. To do so, we used the first multi-scale palaeo-tidal finite element coastal tidal model of the GBR over five time slices (present day, ∼10 ka, ∼12 ka, ∼15 ka and 16.8 ka), representing the position of RSL at 0 m, 20 m, 45 m, 75 m and 96 m below present. We show that favourable conditions for ooid formation only existed for a short period of time between 16.8 and 11 ka. At that time, the Gulf of Capricorn was a wide shallow shelf with strong currents constantly agitating grains, providing rapid burial, exposure and re-burial cycles. We show that these conditions only existed for a short period of time and hence explain the presence of ooid grain formation in the GBR at that time. We propose ooids formed within the Capricorn Channel at a time of lower RSL than expected and then underwent sub-tidal transportation to their final deposition place via tidal currents, explaining the inconsistency with their age and the depth at which they were found

    Observational Study Design in Veterinary Pathology, Part 1: Study Design

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    Observational studies are the basis for much of our knowledge of veterinary pathology and are highly relevant to the daily practice of pathology. However, recommendations for conducting pathology-based observational studies are not readily available. In part 1 of this series, we offer advice on planning and conducting an observational study with examples from the veterinary pathology literature. Investigators should recognize the importance of creativity, insight, and innovation in devising studies that solve problems and fill important gaps in knowledge. Studies should focus on specific and testable hypotheses, questions, or objectives. The methodology is developed to support these goals. We consider the merits and limitations of different types of analytic and descriptive studies, as well as of prospective vs retrospective enrollment. Investigators should define clear inclusion and exclusion criteria and select adequate numbers of study subjects, including careful selection of the most appropriate controls. Studies of causality must consider the temporal relationships between variables and the advantages of measuring incident cases rather than prevalent cases. Investigators must consider unique aspects of studies based on archived laboratory case material and take particular care to consider and mitigate the potential for selection bias and information bias. We close by discussing approaches to adding value and impact to observational studies. Part 2 of the series focuses on methodology and validation of methods

    Spatial Variation among Lakes within Landscapes: Ecological Organization along Lake Chains

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    Although limnologists have long been interested in regional patterns in lake attributes, only recently have they considered lakes connected and organized across the landscape, rather than as spatially independent entities. Here we explore the spatial organization of lake districts through the concept of landscape position, a concept that considers lakes longitudinally along gradients of geomorphology and hydrology. We analyzed long-term chemical and biological data from nine lake chains (lakes in a series connected through surface or groundwater flow) from seven lake districts of diverse hydrologic and geomorphic settings across North America. Spatial patterns in lake variables driven by landscape position were surprisingly common across lake districts and across a wide range of variables. On the other hand, temporal patterns of lake variables, quantified using synchrony, the degree to which pairs of lakes exhibit similar dynamics through time, related to landscape position only for lake chains with lake water residence times that spanned a wide range and were generally long (close to or greater than 1 year). Highest synchrony of lakes within a lake chain occurred when lakes had short water residence times. Our results from both the spatial and temporal analyses suggest that certain features of the landscape position concept are robust enough to span a wide range of seemingly disparate lake types. The strong spatial patterns observed in this analysis, and some unexplained patterns, suggest the need to further study these scales and to continue to view lake ecosystems spatially, longitudinally, and broadly across the landscape.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42434/1/10021-2-5-395_2n5p395.pd

    Molecular and Antigenic Characterization of Reassortant H3N2 Viruses from Turkeys with a Unique Constellation of Pandemic H1N1 Internal Genes

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    Triple reassortant (TR) H3N2 influenza viruses cause varying degrees of loss in egg production in breeder turkeys. In this study we characterized TR H3N2 viruses isolated from three breeder turkey farms diagnosed with a drop in egg production. The eight gene segments of the virus isolated from the first case submission (FAV-003) were all of TR H3N2 lineage. However, viruses from the two subsequent case submissions (FAV-009 and FAV-010) were unique reassortants with PB2, PA, nucleoprotein (NP) and matrix (M) gene segments from 2009 pandemic H1N1 and the remaining gene segments from TR H3N2. Phylogenetic analysis of the HA and NA genes placed the 3 virus isolates in 2 separate clades within cluster IV of TR H3N2 viruses. Birds from the latter two affected farms had been vaccinated with a H3N4 oil emulsion vaccine prior to the outbreak. The HAl subunit of the H3N4 vaccine strain had only a predicted amino acid identity of 79% with the isolate from FAV-003 and 80% for the isolates from FAV-009 and FAV-0010. By comparison, the predicted amino acid sequence identity between a prototype TR H3N2 cluster IV virus A/Sw/ON/33853/2005 and the three turkey isolates from this study was 95% while the identity between FAV-003 and FAV-009/10 isolates was 91%. When the previously identified antigenic sites A, B, C, D and E of HA1 were examined, isolates from FAV-003 and FAV-009/10 had a total of 19 and 16 amino acid substitutions respectively when compared with the H3N4 vaccine strain. These changes corresponded with the failure of the sera collected from turkeys that received this vaccine to neutralize any of the above three isolates in vitro

    Repeat placental growth factor-based testing in women with suspected preterm pre-eclampsia (PARROT-2): a multicentre, parallel-group, superiority, randomised controlled trial.

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    BackgroundPlacental growth factor (PlGF)-based testing has high diagnostic accuracy for predicting pre-eclampsia needing delivery, significantly reducing time to diagnosis and severe maternal adverse outcomes. The clinical benefit of repeat PlGF-based testing is unclear. We aimed to determine whether repeat PlGF-based testing (using a clinical management algorithm and nationally recommended thresholds) reduces adverse perinatal outcomes in pregnant individuals with suspected preterm pre-eclampsia.MethodsIn this multicentre, parallel-group, superiority, randomised controlled trial, done in 22 maternity units across England, Scotland, and Wales, we recruited women aged 18 years or older with suspected pre-eclampsia between 22 weeks and 0 days of gestation and 35 weeks and 6 days of gestation. Women were randomly assigned (1:1) to revealed repeat PlGF-based testing or concealed repeat testing with usual care. The intervention was not masked to women or partners, or clinicians or data collectors, due to the nature of the trial. The trial statistician was masked to intervention allocation. The primary outcome was a perinatal composite of stillbirth, early neonatal death, or neonatal unit admission. The primary analysis was by the intention-to-treat principle, with a per-protocol analysis restricted to women managed according to their allocation group. The trial was prospectively registered with the ISRCTN registry, ISRCTN 85912420.FindingsBetween Dec 17, 2019, and Sept 30, 2022, 1253 pregnant women were recruited and randomly assigned treatment; one patient was excluded due to randomisation error. 625 women were allocated to revealed repeat PlGF-based testing and 627 women were allocated to usual care with concealed repeat PlGF-based testing (mean age 32·3 [SD 5·7] years; 879 [70%] white). One woman in the concealed repeat PlGF-based testing group was lost to follow-up. There was no significant difference in the primary perinatal composite outcome between the revealed repeat PlGF-based testing group (195 [31·2%]) of 625 women) compared with the concealed repeat PlGF-based testing group (174 [27·8%] of 626 women; relative risk 1·21 [95% CI 0·95-1·33]; p=0·18). The results from the per-protocol analysis were similar. There were four serious adverse events in the revealed repeat PlGF-based testing group and six in the concealed repeat PlGF-based testing group; all serious adverse events were deemed unrelated to the intervention by the site principal investigators and chief investigator.InterpretationRepeat PlGF-based testing in pregnant women with suspected pre-eclampsia was not associated with improved perinatal outcomes. In a high-income setting with a low prevalence of adverse outcomes, universal, routine repeat PlGF-based testing of all individuals with suspected pre-eclampsia is not recommended.FundingTommy's Charity, Jon Moulton Charitable Trust, and National Institute for Health and Care Research Guy's and St Thomas' Biomedical Research Centre

    Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

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    Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

    Developmental Patterns of Doublecortin Expression and White Matter Neuron Density in the Postnatal Primate Prefrontal Cortex and Schizophrenia

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    Postnatal neurogenesis occurs in the subventricular zone and dentate gyrus, and evidence suggests that new neurons may be present in additional regions of the mature primate brain, including the prefrontal cortex (PFC). Addition of new neurons to the PFC implies local generation of neurons or migration from areas such as the subventricular zone. We examined the putative contribution of new, migrating neurons to postnatal cortical development by determining the density of neurons in white matter subjacent to the cortex and measuring expression of doublecortin (DCX), a microtubule-associated protein involved in neuronal migration, in humans and rhesus macaques. We found a striking decline in DCX expression (human and macaque) and density of white matter neurons (humans) during infancy, consistent with the arrival of new neurons in the early postnatal cortex. Considering the expansion of the brain during this time, the decline in white matter neuron density does not necessarily indicate reduced total numbers of white matter neurons in early postnatal life. Furthermore, numerous cells in the white matter and deep grey matter were positive for the migration-associated glycoprotein polysialiated-neuronal cell adhesion molecule and GAD65/67, suggesting that immature migrating neurons in the adult may be GABAergic. We also examined DCX mRNA in the PFC of adult schizophrenia patients (n = 37) and matched controls (n = 37) and did not find any difference in DCX mRNA expression. However, we report a negative correlation between DCX mRNA expression and white matter neuron density in adult schizophrenia patients, in contrast to a positive correlation in human development where DCX mRNA and white matter neuron density are higher earlier in life. Accumulation of neurons in the white matter in schizophrenia would be congruent with a negative correlation between DCX mRNA and white matter neuron density and support the hypothesis of a migration deficit in schizophrenia
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