205 research outputs found

    Trends in gender differences in accidents mortality

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    This study tests five hypotheses concerning trends in gender differences in accidents mortality and accident-related behavior, using data for the US, UK, France, Italy, and Japan, 1950-98. As predicted by the Convergence Hypothesis, gender differences have decreased for amount of driving, motor vehicle accidents mortality, and occupational accidents mortality. However, for many types of accidents mortality, gender differences were stable or increased; these trends often resulted from the differential impact on male and female mortality of general societal trends such as increased illicit drug use or improved health care. Similarly, trends in gender differences in accident-related behavior have shown substantial variation and appear to have been influenced by multiple factors, including gender differences in rates of adoption of different types of innovations.accidents, convergence, diffusion of innovations, Europe, gender, gender differences, Japan, mortality, sex differences, unintentional injuries, USA

    Measuring and modelling plant-driven soil carbon dynamics.

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    Plant root activity and deposition of root carbon (C) into the rhizosphere are known to influence the turnover of existing soil organic matter (SOM) in so- called rhizosphere priming effects (RPE). Thereby soil microbes may access nutrients in SOM which are otherwise unavailable to them. However the magnitudes, drivers and mechanisms of these effects are poorly understood. In this thesis I develop a field system to measure such effects on diurnal, seasonal and longer timescales, and use it to explore RPEs and their drivers in contrasting soils under grass. The field system measures CO₂ fluxes and their ¹³ C isotope composition (δ¹³C) near continuously in large (0.8 m diameter, 1 m deep) lysimeters containing two naturally-structured C₃ soils planted with a C₄ grass. The difference in δ¹³C between C₃ SOM and C₄ plants is used to partition fluxes between plant and soil sources. The system’s accuracy and precision were sufficient to resolve diurnal and seasonal patterns in both plant and soil fluxes. Diurnal changes in plant δ¹³C can cause large partitioning errors. I show how, with long-term datasets with sufficient temporal resolution, part of the dataset can be used to allow for transient shifts in plant and soil δ¹³C. I explored the magnitude and mechanisms of RPEs in the two contrasting soils over two years, and the effect of differences in nitrogen supply. I used solar radiation as a proxy for photosynthesis, root activity and rhizodeposition. I found that seasonal and particularly diurnal patterns in SOM turnover were tightly coupled to solar radiation, and more so than in previously published studies. Model estimates of SOM turnover were improved by the inclusion of solar radiation as an explanatory variable alongside soil moisture and temperature, consistent with RPEs. There was no evidence for differences in RPEs with nitrogen supply in either soil.Otten, Wilfred (Associate) Paterson, Eric (Associate)PhD in Environment and Agrifoo

    Dynamic earthquake triggering response tracks evolving unrest at Sierra Negra volcano, Galápagos Islands

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    The propensity for dynamic earthquake triggering is thought to depend on the local stress state and amplitude of the stress perturbation. However, the nature of this dependency has not been confirmed within a single crustal volume. Here, we show that at Sierra Negra volcano, Galápagos Islands, the intensity of dynamically triggered earthquakes increased as inflation of a magma reservoir elevated the stress state. The perturbation of short-term seismicity within teleseismic surface waves also increased with peak dynamic strain. Following rapid coeruptive subsidence and reduction in stress and background seismicity rates, equivalent dynamic strains no longer triggered detectable seismicity. These findings offer direct constraints on the primary controls on dynamic triggering and suggest that the response to dynamic stresses may help constrain the evolution of volcanic unrest

    New targets for overactive bladder-ICI-RS 2109

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    Aim: To review evidence for novel drug targets that can manage overactive bladder (OAB) symptoms. Methods: A think tank considered evidence from the literature and their own research experience to propose new drug targets in the urinary bladder to characterize their use to treat OAB. Results: Five classes of agents or cellular pathways were considered. (a) Cyclic nucleotide–dependent (cyclic adenosine monophosphate and cyclic guanosine monophosphate) pathways that modulate adenosine triphosphate release from motor nerves and urothelium. (b) Novel targets for β3 agonists, including the bladder wall vasculature and muscularis mucosa. (c) Several TRP channels (TRPV1, TRPV4, TRPA1, and TRPM4) and their modulators in affecting detrusor overactivity. (d) Small conductance Ca2+-activated K+ channels and their influence on spontaneous contractions. (e) Antifibrosis agents that act to modulate directly or indirectly the TGF-β pathway—the canonical fibrosis pathway. Conclusions: The specificity of action remains a consideration if particular classes of agents can be considered for future development as receptors or pathways that mediate actions of the above mentioned potential agents are distributed among most organ systems. The tasks are to determine more detail of the pathological changes that occur in the OAB and how the specificity of potential drugs may be directed to bladder pathological changes. An important conclusion was that the storage, not the voiding, phase in the micturition cycle should be investigated and potential targets lie in the whole range of tissue in the bladder wall and not just detrusor

    OpenContrails: Benchmarking Contrail Detection on GOES-16 ABI

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    Contrails (condensation trails) are line-shaped ice clouds caused by aircraft and are likely the largest contributor of aviation-induced climate change. Contrail avoidance is potentially an inexpensive way to significantly reduce the climate impact of aviation. An automated contrail detection system is an essential tool to develop and evaluate contrail avoidance systems. In this paper, we present a human-labeled dataset named OpenContrails to train and evaluate contrail detection models based on GOES-16 Advanced Baseline Imager (ABI) data. We propose and evaluate a contrail detection model that incorporates temporal context for improved detection accuracy. The human labeled dataset and the contrail detection outputs are publicly available on Google Cloud Storage at gs://goes_contrails_dataset

    On allowing for transient variation in end-member δ13C values in partitioning soil C fluxes from net ecosystem respiration

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    The use of stable isotope analysis to resolve ecosystem respiration into its plant and soil components rests on how well the end-member isotope signatures (δ13C) are characterised. In general, it is assumed that end-member values are constant over time. However, there are necessarily diurnal and other transient variations in end-members with environmental conditions. We analyse diurnal and seasonal patterns of ecosystem respiration and its δ13C in a C4 grass growing in a C3 soil using fixed and diurnally varying plant and soil δ13C end-members. We measure the end-members independently, and we assess the effects of expected variation in values. We show that variation in end-members within realistic ranges, particularly diurnal changes in the plant end-member, can cause partitioning errors of 40% during periods of high plant growth. The effect depends on how close the end-member is to the measured net respiration δ13C, that is, the proportion of the respiration due to that end-member. We show light-driven variation in plant end-members can cause substantial distortion of partitioned soil organic matter (SOM) flux patterns on a diurnal scale and cause underestimation of daily to annual SOM turnover of approximately 25%. We conclude that, while it is not practicable to independently measure the full temporal variation in end-member values over a growing season, this error may be adjusted for by using a diurnally varying δ13Cplant

    The Effects of Tropical Cyclone-Generated Deposition on the Sustainability of the Pearl River Marsh, Louisiana: The Importance of the Geologic Framework

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    Shoreline retreat is a tremendously important issue along the coast of the northern Gulf of Mexico, especially in Louisiana. Although this marine transgression results from a variety of causes, the crucial factor is the difference between marsh surface elevation and rising sea levels. In most cases, the primary cause of a marsh's inability to keep up with sea level is the lack of input of inorganic material. Although tropical cyclones provide an important source of such sediment, little effort has been made to determine the point of origin of the deposited material. In this study we use sedimentary, geochemical and biogeochemical data to identify the bed of the Pearl River and/or Lake Borgne as the source of a ~5 cm thick clastic layer deposited on the surface of the Pearl River marsh on the Louisiana/Mississippi border. Radiochemical chronologies and sedimentary evidence indicate that this layer was associated with the passage of Hurricane Katrina in 2005. As this material would otherwise have been lost to the system, this deposition indicates a net gain to marsh surface elevation. Accretion rates, determined from 137Cs and 14C profiles and the use of the Katrina layer as a stratigraphic marker, indicate that short-term (~50 years) rates are as much as an order of magnitude higher than the long- term (1000s of years) rates. We suggest that the marsh's geologic setting in an incised river valley with steep vertical constraints and a large fluvial discharge, promotes rapid accretion rates, with rates accelerating as the sea moves inland, due to extended hydroperiods and the input of clastic material from both the marine and terrestrial sides. These rates are especially large when compared to accretion occurring in the more common open marshes fringing the Gulf that lack fluvial input. The difference is particularly large when related to marsh recovery/regrowth following the deposition of thick hurricane-generated clastic layers. Given the number of similar incised river valleys along the Gulf Coast, we believe that understanding the processes controlling marsh accretion in such environments is essential in evaluating marsh sustainability on a regional basis

    Optical and thermal analysis of the light-heat conversion process employing an antenna-based hybrid plasmonic waveguide for HAMR

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    We investigate a tapered, hybrid plasmonic waveguide which has previously been proposed as an optically efficient near-field transducer (NFT), or component thereof, in several devices which aim to exploit nanofocused light. We numerically analyze how light is transported through the waveguide and ultimately focused via effective-mode coupling and taper optimization. Crucial dimensional parameters in this optimization process are identified that are not only necessary to achieve maximum optical throughput, but also optimum thermal performance with specific application towards heat-assisted magnetic recording (HAMR). It is shown that existing devices constructed on similar waveguides may benefit from a heat spreader to avoid deformation of the plasmonic element which we achieve with no cost to the optical efficiency. For HAMR, our design is able to surpass many industry requirements in regard to both optical and thermal efficiency using pertinent figure of merits like 8.5% optical efficiency.Comment: 14 pages, 7 figures, and 3 tables. Published version: see https://doi.org/10.1364/OE.26.001752. Related works: see https://doi.org/10.1364/oe.22.011236, https://doi.org/10.1364/oe.26.030292, and https://doi.org/10.1063/5.0044490. Keywords: Integrated Optics; Components; Integrated Optics Devices; Surface Plasmons; Plasmonic

    Optical and thermal analysis of the light-heat conversion process employing an antenna-based hybrid plasmonic waveguide for HAMR

    Get PDF
    We investigate a tapered, hybrid plasmonic waveguide which has previously been proposed as an optically efficient near-field transducer (NFT), or component thereof, in several devices which aim to exploit nanofocused light. We numerically analyze how light is transported through the waveguide and ultimately focused via effective-mode coupling and taper optimization. Crucial dimensional parameters in this optimization process are identified that are not only necessary to achieve maximum optical throughput, but also optimum thermal performance with specific application towards heat-assisted magnetic recording (HAMR). It is shown that existing devices constructed on similar waveguides may benefit from a heat spreader to avoid deformation of the plasmonic element which we achieve with no cost to the optical efficiency. For HAMR, our design is able to surpass many industry requirements in regard to both optical and thermal efficiency using pertinent figure of merits like 8.5% optical efficiency
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