823 research outputs found

    New Concepts for Quasi-Optical Structures for Use with Gyrotron Systems

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    High-power diplexers for plasma heating and diagnostic systems: developments, experiments, and prospects

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    Stress-Related Psychopathology During the COVID-19 Pandemic

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    The COVID-19 pandemic has introduced widespread societal changes that have required ongoing adaptation. Unsurprisingly, stress-related psychopathology has increased during the pandemic, in both children and adults. We review these patterns through the lens of several leading conceptual models of the link between stress and psychopathology. Some of these models focus on characteristics of environmental stressors—including cumulative risk, specific stressor types, and stress sensitization approaches. Understanding the specific aspects of environmental stressors that are most likely to lead to psychopathology can shed light on who may be in most need of clinical intervention. Other models center on factors that can buffer against the onset of psychopathology following stress and the mechanisms through which stressors contribute to emergent psychopathology. These models highlight specific psychosocial processes that may be most usefully targeted by interventions to reduce stress-related psychopathology. We review evidence for each of these stress models in the context of other widescale community-level disruptions, like natural disasters and terrorist attacks, alongside emerging evidence for these stress pathways from the COVID-19 pandemic. We discuss clinical implications for developing interventions to reduce stress-related psychopathology during the pandemic, with a focus on brief, digital interventions that may be more accessible than traditional clinical services

    Numerical and Experimental Investigations of Polyurethane Foam for Use as Cask Impact Limiter in Accidental Drop Scenarios -12099

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    ABSTRACT Rigid, closed-cell polyurethane foams are frequently used as cask impact limiters in nuclear materials and hazardous waste transport due to their high energy-absorption potential. When assessing the cask integrity in accidental scenarios based on numerical simulations, a description of the foam damping properties is required for different strain rates and for a wide temperature range with respect to waste heat generation in conjunction with critical operating and environmental conditions. Implementation and adaption of a respective finite element material model strongly relies on an appropriate experimental data base. Even though extensive impact experiments were conducted e.g. in Sandia National Laboratories [1], Savannah River National Laboratory Hence, BAM who is in charge of the mechanical evaluation of such packages within the approval procedure in Germany, incorporated systematic test series into a comprehensive research project aimed to develop numerical methods for a couple of damping materials. In a first step, displacement driven compression tests have been performed on confined, cubic specimens at five loading rates ranging from 0.02 mm/s to 3 m/s at temperatures between +90°C and -40°C. Materials include two different polyurethane foam types called FR3718 and FR3730 having densities of 280 kg/m³ and 488 kg/m³ from the product line-up of General Plastics Manufacturing Company Currently, the selected numerical material input values are validated and optimized by means of more complex loading configurations with the prospect of establishing methods applicable to impact limiters under severe accidental conditions. The reference data base is provided by experiments, where weights between 212 kg and 1200 kg have been dropped from heights between 1.25 m and 7 m on confined 10 cm cubic foam specimens. By presenting the deviations between experimental values and the corresponding output of finite element simulations, the potentials and restrictions of the resulting models are highlighted
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