930 research outputs found

    Artificial Lightning : A Summary of a Study of Natural and Artificial Lightning Discharges

    Get PDF

    On the influence that the ground electrode diameter has in the propulsion efficiency of an asymmetric capacitor in nitrogen gas

    Full text link
    In this work the propulsion force developed in an asymmetric capacitor will be calculated for three different diameters of the ground electrode. The used ion source is a small diameter wire, which generates a positive corona discharge in nitrogen gas directed to the ground electrode. By applying the fluid dynamic and electrostatic theories all hydrodynamic and electrostatic forces that act on the considered geometries will be computed in an attempt to provide a physical insight on the force mechanism that acts on the asymmetrical capacitors, and also to understand how to increase the efficiency of propulsion.Comment: 13 pages, 8 figures, Accepted for publication in "Physics of Plasmas

    Physical Properties of Complex C Halo Clouds

    Get PDF
    Observations from the Galactic Arecibo L-Band Feed Array HI (GALFA-HI) Survey of the tail of Complex C are presented and the halo clouds associated with this complex cataloged. The properties of the Complex C clouds are compared to clouds cataloged at the tail of the Magellanic Stream to provide insight into the origin and destruction mechanism of Complex C. Magellanic Stream and Complex C clouds show similarities in their mass distributions (slope = -0.7 and -0.6, respectively) and have a common linewidth of 20 - 30 km/s (indicative of a warm component), which may indicate a common origin and/or physical process breaking down the clouds. The clouds cataloged at the tail of Complex C extend over a mass range of 10^1.1 to 10^4.8 solar masses, sizes of 10^1.2 to 10^2.6 pc, and have a median volume density of 0.065 cm^(-3) and median pressure of (P/k) = 580 K cm^{-3}. We do not see a prominent two-phase structure in Complex C, possibly due to its low metallicity and inefficient cooling compared to other halo clouds. From assuming the Complex C clouds are in pressure equilibrium with a hot halo medium, we find a median halo density of 5.8 x 10^(-4) cm^(-3), which given a constant distance of 10 kpc, is at a z-height of ~3 kpc. Using the same argument for the Stream results in a median halo density of 8.4 x 10^(-5) x (60kpc/d) cm^(-3). These densities are consistent with previous observational constraints and cosmological simulations. We also assess the derived cloud and halo properties with three dimensional grid simulations of halo HI clouds and find the temperature is generally consistent within a factor of 1.5 and the volume densities, pressures and halo densities are consistent within a factor of 3.Comment: Accepted for publication in AJ. 54 pages, including 6 tables and 16 figure

    Multiphysics simulation of corona discharge induced ionic wind

    Full text link
    Ionic wind devices or electrostatic fluid accelerators are becoming of increasing interest as tools for thermal management, in particular for semiconductor devices. In this work, we present a numerical model for predicting the performance of such devices, whose main benefit is the ability to accurately predict the amount of charge injected at the corona electrode. Our multiphysics numerical model consists of a highly nonlinear strongly coupled set of PDEs including the Navier-Stokes equations for fluid flow, Poisson's equation for electrostatic potential, charge continuity and heat transfer equations. To solve this system we employ a staggered solution algorithm that generalizes Gummel's algorithm for charge transport in semiconductors. Predictions of our simulations are validated by comparison with experimental measurements and are shown to closely match. Finally, our simulation tool is used to estimate the effectiveness of the design of an electrohydrodynamic cooling apparatus for power electronics applications.Comment: 24 pages, 17 figure

    The Ursinus Weekly, October 28, 1963

    Get PDF
    69 women pledge sororities at bid signing Saturday • Class of 1966 to sell slaves at Bazaar • Annual Founders Day November 3; Five honorary degrees to be awarded • Navy debate team bows UC 31-29 • Young Democrats begin activities • Halloween reading night October 30 • Indians warpath at Jr. turnabout • Pre-med society hears Dr. French • Biggest bargain of the year: 1964 Ruby sales begin • $8500 scholarships available for Univ. of Hawaii • Editorial: Which way out?; Action, please • Letters to the editor • Conservatism reconsidered: Spencer\u27s article decried • Human understanding theme of presentation • Fundamental need unfilled • Penna. seeks librarians • Groups schedule career conf. • Federal service exam November 23 • Greek gleanings • Kaffee klatsch: Foreign students reception • Bears topple Swarthmore on fine team effort, 14-6 • Player of the week • Soccer team bows twice • Hockey team still undefeatedhttps://digitalcommons.ursinus.edu/weekly/1255/thumbnail.jp

    Clinical Performance Feedback Intervention Theory (CP-FIT): a new theory for designing, implementing, and evaluating feedback in health care based on a systematic review and meta-synthesis of qualitative research

    Get PDF
    Background: Providing health professionals with quantitative summaries of their clinical performance when treating specific groups of patients (“feedback”) is a widely used quality improvement strategy, yet systematic reviews show it has varying success. Theory could help explain what factors influence feedback success, and guide approaches to enhance effectiveness. However, existing theories lack comprehensiveness and specificity to health care. To address this problem, we conducted the first systematic review and synthesis of qualitative evaluations of feedback interventions, using findings to develop a comprehensive new health care-specific feedback theory. Methods: We searched MEDLINE, EMBASE, CINAHL, Web of Science, and Google Scholar from inception until 2016 inclusive. Data were synthesised by coding individual papers, building on pre-existing theories to formulate hypotheses, iteratively testing and improving hypotheses, assessing confidence in hypotheses using the GRADE-CERQual method, and summarising high-confidence hypotheses into a set of propositions. Results: We synthesised 65 papers evaluating 73 feedback interventions from countries spanning five continents. From our synthesis we developed Clinical Performance Feedback Intervention Theory (CP-FIT), which builds on 30 pre-existing theories and has 42 high-confidence hypotheses. CP-FIT states that effective feedback works in a cycle of sequential processes; it becomes less effective if any individual process fails, thus halting progress round the cycle. Feedback’s success is influenced by several factors operating via a set of common explanatory mechanisms: the feedback method used, health professional receiving feedback, and context in which feedback takes place. CP-FIT summarises these effects in three propositions: (1) health care professionals and organisations have a finite capacity to engage with feedback, (2) these parties have strong beliefs regarding how patient care should be provided that influence their interactions with feedback, and (3) feedback that directly supports clinical behaviours is most effective. Conclusions: This is the first qualitative meta-synthesis of feedback interventions, and the first comprehensive theory of feedback designed specifically for health care. Our findings contribute new knowledge about how feedback works and factors that influence its effectiveness. Internationally, practitioners, researchers, and policy-makers can use CP-FIT to design, implement, and evaluate feedback. Doing so could improve care for large numbers of patients, reduce opportunity costs, and improve returns on financial investments

    2021 Nevada High School Youth Risk Behavior Survey (YRBS) Washoe County Special Report

    Get PDF
    Priority health risk behaviors (i.e. preventable behaviors that contribute to the leading causes of morbidity and mortality) are often established during childhood and adolescence and extend into adulthood. Ongoing surveillance of youth risk behaviors is critical for the design, implementation, and evaluation of public health interventions to improve adolescent health. The Youth Risk Behavior Survey (YRBS) is a national surveillance system that was established in 1991 by the Centers for Disease Control and Prevention (CDC) to monitor the prevalence of health risk behaviors among youth. The Nevada High School YRBS is a biennial, anonymous, and voluntary survey of students in 9th through 12th grade in regular public, charter, and alternative schools. Students self-report their behaviors in six major areas of health that directly lead to morbidity and mortality; these include: 1) Behaviors that contribute to unintentional injuries and violence; 2) Sexual behaviors that contribute to human immunodeficiency virus (HIV) infection, other sexually transmitted diseases, and unintended pregnancy; 3) Tobacco use; 4) Alcohol and other drug use; 5) Unhealthy dietary behaviors; and 6) Physical inactivity

    2021 Nevada Middle School Youth Risk Behavior Survey (YRBS) Clark County Special Report

    Get PDF
    Priority health risk behaviors (i.e. preventable behaviors that contribute to the leading causes of morbidity and mortality) are often established during childhood and adolescence and extend into adulthood. Ongoing surveillance of youth risk behaviors is critical for the design, implementation, and evaluation of public health interventions to improve adolescent health. The Youth Risk Behavior Survey (YRBS) is a national surveillance system that was established in 1991 by the Centers for Disease Control and Prevention (CDC) to monitor the prevalence of health risk behaviors among youth. YRBS data are routinely collected on high school students, but only a few states collect data in middle schools. The Nevada Middle School YRBS is biennial, anonymous and voluntary survey of students in 6th through 8th grade in regular public, charter, and alternative schools. Students self-report their behaviors in five major areas of health that directly lead to morbidity and mortality, these include: 1) Behaviors that contribute to unintentional injuries and violence; 2) Tobacco use; 3) Alcohol and other drug use; 4) Unhealthy dietary behaviors; and 5) Physical inactivity

    2021 Nevada Middle School Youth Risk Behavior Survey (YRBS) Washoe County Special Report

    Get PDF
    Priority health risk behaviors (i.e. preventable behaviors that contribute to the leading causes of morbidity and mortality) are often established during childhood and adolescence and extend into adulthood. Ongoing surveillance of youth risk behaviors is critical for the design, implementation, and evaluation of public health interventions to improve adolescent health. The Youth Risk Behavior Survey (YRBS) is a national surveillance system that was established in 1991 by the Centers for Disease Control and Prevention (CDC) to monitor the prevalence of health risk behaviors among youth. YRBS data are routinely collected on high school students, but only a few states collect data in middle schools. The Nevada Middle School YRBS is biennial, anonymous and voluntary survey of students in 6th through 8th grade in regular public, charter, and alternative schools. Students self-report their behaviors in five major areas of health that directly lead to morbidity and mortality, these include: 1) Behaviors that contribute to unintentional injuries and violence; 2) Tobacco use; 3) Alcohol and other drug use; 4) Unhealthy dietary behaviors; and 5) Physical inactivity

    Measurement of mechanical vibrations excited in aluminium resonators by 0.6 GeV electrons

    Get PDF
    We present measurements of mechanical vibrations induced by 0.6 GeV electrons impinging on cylindrical and spherical aluminium resonators. To monitor the amplitude of the resonator's vibrational modes we used piezoelectric ceramic sensors, calibrated by standard accelerometers. Calculations using the thermo-acoustic conversion model, agree well with the experimental data, as demonstrated by the specific variation of the excitation strengths with the absorbed energy, and with the traversing particles' track positions. For the first longitudinal mode of the cylindrical resonator we measured a conversion factor of 7.4 +- 1.4 nm/J, confirming the model value of 10 nm/J. Also, for the spherical resonator, we found the model values for the L=2 and L=1 mode amplitudes to be consistent with our measurement. We thus have confirmed the applicability of the model, and we note that calculations based on the model have shown that next generation resonant mass gravitational wave detectors can only be expected to reach their intended ultra high sensitivity if they will be shielded by an appreciable amount of rock, where a veto detector can reduce the background of remaining impinging cosmic rays effectively.Comment: Tex-Article with epsfile, 34 pages including 13 figures and 5 tables. To be published in Rev. Scient. Instr., May 200
    • …
    corecore