3,899 research outputs found

    Playing for an Active Community: Sports Participation and Civic Engagement

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    Research on civic engagement in associations posits benefits at various levels in society. Critical perspective holds that sports may alternately teach positive social behaviors while reinforcing discriminatory stereotypes in its participants. The research question becomes, does participation in youth sports actually lead to civic engagement later in life? Using a longitudinal data set, I find that after controlling for other factors, there still is an indirect positive correlation between team sports participation and volunteering as a young adult. Analysis indicates that sports participation as an adolescent significantly accounts for sports participation as a young adult which in turn, influences volunteering

    A simple reactive-transport model of calcite precipitation in soils and other porous media

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    Calcite formation in soils and other porous media generally occurs around a localised source of reactants, such as a plant root or soil macro-pore, and the rate depends on the transport of reactants to and from the precipitation zone as well as the kinetics of the precipitation reaction itself. However most studies are made in well mixed systems, in which such transport limitations are largely removed. We developed a mathematical model of calcite precipitation near a source of base in soil, allowing for transport limitations and precipitation kinetics. We tested the model against experimentally-determined rates of calcite precipitation and reactant concentration–distance profiles in columns of soil in contact with a layer of HCO3−-saturated exchange resin. The model parameter values were determined independently. The agreement between observed and predicted results was satisfactory given experimental limitations, indicating that the model correctly describes the important processes. A sensitivity analysis showed that all model parameters are important, indicating a simpler treatment would be inadequate. The sensitivity analysis showed that the amount of calcite precipitated and the spread of the precipitation zone were sensitive to parameters controlling rates of reactant transport (soil moisture content, salt content, pH, pH buffer power and CO2 pressure), as well as to the precipitation rate constant. We illustrate practical applications of the model with two examples: pH changes and CaCO3 precipitation in the soil around a plant root, and around a soil macro-pore containing a source of base such as urea

    Progress in the Theory of Electron-Beam Deflection

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    Analysis, simulation, and design of electron-beam-deflection systems are reviewed in light of the current state of theoretical understanding. A brief review of the physical principles is followed by a detailed discussion of electrostatic, magnetostatic, mixed-field, traveling-wave, and scan-expansion systems. Each methodology is examined from a triple perspective: calculation of electromagnetic fields, calculation of electron trajectories, and calculation of the ensemble of trajectories forming the beam. Applications discussed include deflectors for television displays, lithography, scanning microscopes, and CRT oscillography. Developments of the last ten years are stressed, thereby supplementing and updating the author\u27s previous review on this subject. In field calculation, recent developments in the use of numerical methods on computers dominate. These methods include finite-difference, finite-element, and charge-density or integral-equation techniques. In trajectory calculations, increasing use of numerical integration as well as improvements and extensions of the aberration theory are found. In treatment of the beam bundle, the growing sophistication of numerical deflected-beam models has lead to increased use of aberration figures, current-density plots, and phase-space methods

    Particle Astrophysics and Cosmology: Cosmic Laboratories for New Physics (Summary of the Snowmass 2001 P4 Working Group)

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    The past few years have seen dramatic breakthroughs and spectacular and puzzling discoveries in astrophysics and cosmology. In many cases, the new observations can only be explained with the introduction of new fundamental physics. Here we summarize some of these recent advances. We then describe several problem in astrophysics and cosmology, ripe for major advances, whose resolution will likely require new physics.Comment: 27 pages, 14 figure

    Letter from the Ritz-Carlton to Robert Goelet

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    https://digitalcommons.salve.edu/goelet-personal-expenses/1232/thumbnail.jp

    Sensitivity to new supersymmetric thresholds through flavour and CP violating physics

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    Treating the MSSM as an effective theory below a threshold scale Lambda, we study the consequences of having dimension-five operators in the superpotential for flavour and CP-violating processes. Below the supersymmetric threshold such terms generate flavour changing and/or CP-odd effective operators of dimension six composed from the Standard Model fermions, that have the interesting property of decoupling linearly with the threshold scale, i.e. as 1/(Lambda m_soft), where m_soft is the scale of soft supersymmetry breaking. The assumption of weak-scale supersymmetry, together with the stringent limits on electric dipole moments and lepton flavour-violating processes, then provides sensitivity to Lambda as high as 10^7-10^9 GeV. We discuss the varying sensitivity to these scales within several MSSM benchmark scenarios and also outline the classes of UV physics which could generate these operators.Comment: 28 pages, 9 figure

    Monitoring Winter Stress Vulnerability of High-Latitude Understory Vegetation Using Intraspecific Trait Variability and Remote Sensing Approaches

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    In this study, we focused on three species that have proven to be vulnerable to winter stress: Empetrum nigrum, Vaccinium vitis-idaea and Hylocomium splendens. Our objective was to determine plant traits suitable for monitoring plant stress as well as trait shifts during spring. To this end, we used a combination of active and passive handheld normalized difference vegetation index (NDVI) sensors, RGB indices derived from ordinary cameras, an optical chlorophyll and flavonol sensor (Dualex), and common plant traits that are sensitive to winter stress, i.e. height, specific leaf area (SLA). Our results indicate that NDVI is a good predictor for plant stress, as it correlates well with height (r = 0.70, p < 0.001) and chlorophyll content (r = 0.63, p < 0.001). NDVI is also related to soil depth (r = 0.45, p < 0.001) as well as to plant stress levels based on observations in the field (r = −0.60, p < 0.001). Flavonol content and SLA remained relatively stable during spring. Our results confirm a multi-method approach using NDVI data from the Sentinel-2 satellite and active near-remote sensing devices to determine the contribution of understory vegetation to the total ecosystem greenness. We identified low soil depth to be the major stressor for understory vegetation in the studied plots. The RGB indices were good proxies to detect plant stress (e.g. Channel G%: r = −0.77, p < 0.001) and showed high correlation with NDVI (r = 0.75, p < 0.001). Ordinary cameras and modified cameras with the infrared filter removed were found to perform equally well

    Renal protection in diabetes: lessons from ONTARGET®

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    Hypertension is an important independent risk factor for renal disease. If hypertension and chronic renal disease co-exist, as is common in patients with diabetes mellitus, the risk of cardiovascular disease is heightened. The importance of rigorous blood pressure control is recognized in current guidelines, with a recommended target of office blood pressure of < 130/80 mmHg; although ambulatory blood pressure may be more appropriate in order to identify the 24-hour hypertensive burden. Even lower blood pressure may further reduce the progression of chronic kidney disease, but the incidence of cardiovascular events may increase. Albuminuria not only indicates renal damage, but is also a powerful predictor of cardiovascular morbidity and mortality at least in patients with high cardiovascular risk and potentially pre-existing vascular damage. Management of the multiple factors for renal and cardiovascular disease is mandatory in the diabetic patient. The renin-angiotensin system (RAS) plays a pivotal role in the progression of renal disease, as well as in hypertension and target-organ damage. The use of agents that target the RAS confer renoprotection in addition to antihypertensive activity. There is extensive evidence of the renoprotective effect of angiotensin II receptor blockers (ARBs), and specifically telmisartan. In addition to providing 24-hour blood pressure control, clinical studies in patients with diabetes show that telmisartan improves renal endothelial function, prevents progression from microalbuminuria to macroalbuminuria, slows the decline in glomerular filtration rate and reduces proteinuria in overt nephropathy. These effects cannot be solely attributed to blood pressure control. In contrast to other members of the ARB class, the renoprotective effect of telmisartan is not confined to the management of diabetic nephropathy; slowing the progression of albuminuria has been demonstrated in the ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET®), which included diabetic and non-diabetic patients at high risk of cardiovascular events
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