17,815 research outputs found

    China\u27s Unethical Economic Development Practices

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    The purpose of this research paper is to inform the public about some of the unethical economic development practices that China is performing with their citizens and global partners. These activities include escalating the national GDP at the detriment of their citizens through forced relocations in order to build new cities, dividing families with harmful public policies, and the imbalance between their citizens’ annual earnings and housing costs. Also discussed is the environmental pollution of the air, water, and soil, and poorly treating their international constituents when asked to provide consulting services to their nation

    A split-beam probe-pump-probe scheme for femtosecond time resolved protein X-ray crystallography

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    In order to exploit the femtosecond pulse duration of X-ray Free-Electron Lasers (XFEL) operating in the hard X-ray regime for ultrafast time-resolved protein crystallography experiments, critical parameters that determine the crystallographic signal-to-noise (I/σI) must be addressed. For single-crystal studies under low absorbed dose conditions, it has been shown that the intrinsic pulse intensity stability as well as mode structure and jitter of this structure, significantly affect the crystallographic signal-to-noise. Here, geometrical parameters are theoretically explored for a three-beam scheme: X-ray probe, optical pump, X-ray probe (or “probe-pump-probe”) which will allow experimental determination of the photo-induced structure factor amplitude differences, ΔF, in a ratiometric manner, thereby internally referencing the intensity noise of the XFEL source. In addition to a non-collinear split-beam geometry which separates un-pumped and pumped diffraction patterns on an area detector, applying an additional convergence angle to both beams by focusing leads to integration over mosaic blocks in the case of well-ordered stationary protein crystals. Ray-tracing X-ray diffraction simulations are performed for an example using photoactive yellow protein crystals in order to explore the geometrical design parameters which would be needed. The specifications for an X-ray split and delay instrument that implements both an offset angle and focused beams are discussed, for implementation of a probe-pump-probe scheme at the European XFEL. We discuss possible extension of single crystal studies to serial femtosecond crystallography, particularly in view of the expected X-ray damage and ablation due to the first probe pulse

    Radial convection of finite ion temperature, high amplitude plasma blobs

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    We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line with conditions found in tokamak scrape-off-layers (SOL) regions. Varying the ion temperature, the initial blob width, and the initial amplitude, we found an FLR dominated regime where the blob behavior is significantly different from what is predicted by cold-ion models. The transition to this regime is very well described by the ratio of the ion gyroradius to the characteristic gradient scale length of the blob. We compare the global gyrofluid model with a partly linearized local model. For low ion temperatures we find that simulations of the global model show more coherent blobs with an increased cross-field transport compared to blobs simulated with the local model. The maximal blob amplitude is significantly higher in the global simulations than in the local ones. When the ion temperature is comparable to the electron temperature, global blob simulations show a reduced blob coherence and a decreased cross-field transport in comparison with local blob simulations

    The influence of temperature dynamics and dynamic finite ion Larmor radius effects on seeded high amplitude plasma blobs

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    Thermal effects on the perpendicular convection of seeded pressure blobs in the scrape-off layer of magnetised fusion plasmas are investigated. Our numerical study is based on a four field full-F gyrofluid model, which entails the consistent description of high fluctuation amplitudes and dynamic finite Larmor radius effects. We find that the maximal radial blob velocity increases with the square root of the initial pressure perturbation and that a finite Larmor radius contributes to highly compact blob structures that propagate in the poloidal direction. An extensive parameter study reveals that a smooth transition to this compact blob regime occurs when the finite Larmor radius effect strength, defined by the ratio of the magnetic field aligned component of the ion diamagnetic to the E⃗×B⃗\vec{E}\times\vec{B} vorticity, exceeds unity. The maximal radial blob velocities agree excellently with the inertial velocity scaling law over more than an order of magnitude. We show that the finite Larmor radius effect strength affects the poloidal and total particle transport and present an empirical scaling law for the poloidal and total blob velocities. Distinctions to the blob behaviour in the isothermal limit with constant finite Larmor radius effects are highlighted

    Design study of test models of maneuvering aircraft configurations for the National Transonic Facility (NTF)

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    The feasibility of designing advanced technology, highly maneuverable, fighter aircraft models to achieve full scale Reynolds number in the National Transonic Facility (NTF) is examined. Each of the selected configurations are tested for aeroelastic effects through the use of force and pressure data. A review of materials and material processes is also included

    High Q Cavity Induced Fluxon Bunching in Inductively Coupled Josephson Junctions

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    We consider fluxon dynamics in a stack of inductively coupled long Josephson junctions connected capacitively to a common resonant cavity at one of the boundaries. We study, through theoretical and numerical analysis, the possibility for the cavity to induce a transition from the energetically favored state of spatially separated shuttling fluxons in the different junctions to a high velocity, high energy state of identical fluxon modes.Comment: 8 pages, 5 figure

    Are physical education policies working? A snapshot from San Francisco, 2011.

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    IntroductionSchool physical education (PE) has been identified as a critical public health tool to increase physical activity among youths. We sought to objectively assess compliance with PE quantity mandates and quality recommendations in a large urban California school district.MethodsWe collected PE schedules and systematically observed PE lessons (n=154) in 20 elementary, 4 middle, and 4 high schools from February through May 2011.ResultsOn the basis of schools' master schedules, 83% of elementary schools met the California state mandate of 100 PE minutes per week. Teachers' actual schedules indicated that 20% of schools met the mandate, and observation showed that only 5% were in compliance. All middle and high schools met the mandated 200 minutes per week. On average, classes at all school levels met the recommended 50% of PE lesson time in moderate-to-vigorous physical activity. No teacher- or school-level factors significantly predicted PE quantity, but credentialed elementary PE teachers spent more time building students' motor skills.ConclusionsOur results suggest that current national estimates of PE, which are based on schools' self-report, overestimate the amount of PE provided in elementary schools. Although more than half of PE class time was spent in moderate-to-vigorous physical activity, total physical activity in elementary schools from PE is minimal and may do little to contribute to students' overall health
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