3,418 research outputs found

    Deconstructing therapy outcome measurement with Rasch analysis of a measure of general clinical distress: the Symptom Checklist-90-Revised

    Get PDF
    Rasch analysis was used to illustrate the usefulness of item-level analyses for evaluating a common therapy outcome measure of general clinical distress, the Symptom Checklist-90-Revised (SCL-90-R; Derogatis, 1994). Using complementary therapy research samples, the instrument's 5-point rating scale was found to exceed clients' ability to make reliable discriminations and could be improved by collapsing it into a 3-point version (combining scale points 1 with 2 and 3 with 4). This revision, in addition to removing 3 misfitting items, increased person separation from 4.90 to 5.07 and item separation from 7.76 to 8.52 (resulting in alphas of .96 and .99, respectively). Some SCL-90-R subscales had low internal consistency reliabilities; SCL-90-R items can be used to define one factor of general clinical distress that is generally stable across both samples, with two small residual factors

    Using Microanalytical Simulation Methods in Educational Evaluation: An Exploratory Study

    Get PDF
    Scientifically based research used to inform evidence based school reform efforts has been required by the federal government in order to receive grant funding since the reenactment of No Child Left Behind (2002). Educational evaluators are thus faced with the challenge to use rigorous research designs to establish causal relationships. However, access to student-level longitudinal or comparison group data is often scarce, which significantly restricts researchers’ choice of research design. Although most state departments of education have school- and district-level data available to the public, the individual student-level data that are often needed to perform appropriate statistical analyses are unavailable. This exploratory study demonstrates the process of and provides evidence that microanalytical simulation methods, conducted using Microsoft Excel, may be a useful research tool in the field of education if adequate school-level modeling information is available. These simulation methods may assist in providing greater opportunities to execute more rigorous methodological designs

    The acute effects of whole body vibration on isometric mid-thigh pull performance

    Get PDF
    The purpose of the present investigation was to examine the acute effects of whole body vibration (WBV) on isometric mid-thigh pull force–time curve (FTC) characteristics. Eleven recreationally trained subjects were randomly assigned to three treatment conditions: sham no vibration protocol (T1), vibration protocol 30 Hz 2–4 mm amplitude (T2), and vibration protocol 30 Hz 2–4 mm (T3). After completing a standardized warm-up, the subject stood on a vibration platform with the knee at a 120° angle and performed one of the three interventions. Each treatment condition required the subject to stand on the platform for thirty-second treatments, each separated by thirty seconds of recovery. Five minutes after the completion of the treatment conditions, the subjects performed the isometric mid-thigh pull. All FTCs were analyzed with standardized procedures for peak force (PF) and peak rate of force development (PRFD). A 1 × 3 repeated measures analysis of variance (ANOVA) was used to compare the three treatments. Additionally, coefficients of variance (CV), as well as intraclass and interclass correlations, were performed. There were no significant differences (p \u3e 0.05) for any of the FTC analyses performed in this investigation. The CV and the 95% confidence interval (CI) indicate that the WBV protocol resulted in trivial changes in PF and beneficial changes in PRFD. A 30 Hz 2–4 mm amplitude WBV does not result in a significant increase in isometric mid-thigh pull performance

    Hormone and Adpokine Alterations across Eleven Weeks of Training in Division I Collegiate Throwers: an Exploratory Study

    Get PDF
    Conceptually, it is important to understand the underlying physiological mechanisms of any training program model. This understanding aids the coach/sport scientist in making better choices in manipulating variables in formulating the training model. These underlying mechanisms can be associated with training variable manipulation and fatigue management aspects as well as the overall health of the athlete. Hormone and cytokine concentrations can be linked to alterations resulting from the manipulation of training variables and to subsequent alterations in performance (Haff et al., 2008; Ishigaki et al., 2005; Jurimae et al., 2010; Stone et al., 2007). For example, alterations in the testosterone: cortisol ratio (T:C) has been associated with alterations in training volume as well as physiological aspects such as lean body mass (LBM), fat content and strength/power performance (Haff et al., 2008; Häkkinen, 1989; Stone et al., 2007). Although cytokine production is part of the adaptive process, markedly increased/excessive cytokine production has been related poor fatigue management and over training (Angeli et al., 2004; Jurimae et al., 2010; Smith, 2000). The present study followed NCAA division 1 (D-1) collegiate throwers over a period of an 11 week fall semester preparation-phase block form of periodized training. Volume and intensity alterations and their effects on physiological variables (e.g. neuromuscular, hormonal, cytokine) are a key component in understanding the effects of a training process. Alterations in these physiological variables were tracked over time in Division-1 collegiate throwers

    Electron Heating in Hot Accretion Flows

    Get PDF
    Local (shearing box) simulations of the nonlinear evolution of the magnetorotational instability in a collisionless plasma show that angular momentum transport by pressure anisotropy (ppp_\perp \ne p_\parallel, where the directions are defined with respect to the local magnetic field) is comparable to that due to the Maxwell and Reynolds stresses. Pressure anisotropy, which is effectively a large-scale viscosity, arises because of adiabatic invariants related to pp_\perp and pp_\parallel in a fluctuating magnetic field. In a collisionless plasma, the magnitude of the pressure anisotropy, and thus the viscosity, is determined by kinetic instabilities at the cyclotron frequency. Our simulations show that 50\sim 50 % of the gravitational potential energy is directly converted into heat at large scales by the viscous stress (the remaining energy is lost to grid-scale numerical dissipation of kinetic and magnetic energy). We show that electrons receive a significant fraction ([Te/Ti]1/2\sim [T_e/T_i]^{1/2}) of this dissipated energy. Employing this heating by an anisotropic viscous stress in one dimensional models of radiatively inefficient accretion flows, we find that the radiative efficiency of the flow is greater than 0.5% for M˙104M˙Edd\dot{M} \gtrsim 10^{-4} \dot{M}_{Edd}. Thus a low accretion rate, rather than just a low radiative efficiency, is necessary to explain the low luminosity of many accreting black holes. For Sgr A* in the Galactic Center, our predicted radiative efficiencies imply an accretion rate of 3×108Myr1\approx 3 \times 10^{-8} M_\odot {\rm yr^{-1}} and an electron temperature of 3×1010\approx 3 \times 10^{10} K at 10\approx 10 Schwarzschild radii; the latter is consistent with the brightness temperature inferred from VLBI observations.Comment: to appear in Oct 1 2007 issue of ApJ; corrected grant information and the firehose threshold typ

    Crow Deaths Caused by West Nile Virus during Winter

    Get PDF
    In New York, an epizootic of American crow (Corvus brachyrhynchos) deaths from West Nile virus (WNV) infection occurred during winter 2004–2005, a cold season when mosquitoes are not active. Detection of WNV in feces collected at the roost suggests lateral transmission through contact or fecal contamination

    The Acute Effects of Whole Body Vibration on Isometric Mid-Thigh Pull Performance

    Get PDF
    Acute exposure to vibration has been suggested to produce transient increases in muscular strength (1,2,8), vertical jump displacement (4,8), and power output (2,6,7) recorded while performing various tasks. It has been hypothesized that the reported acute vibration induced increases in performance occur as a result of alterations in neuromuscular stimulation (1,3,4). Specifically, most studies have ascribed the observed improvements to the likeliness of Whole Body Vibration (WBV) in producing a “tonic vibration reflex” (TVR) in which the primary nerve endings of the Ia afferents of the muscle spindle are activated. This is thought to result in the excitation of the alpha-motor neurons and activation of the extrafusal fibers (4) which likely leads to a greater synchronization of motor units as a result of homonymous motor unit contraction. However, not all investigations report improvements in muscular strength (4), vertical jump (7), and power production in response to acute vibration (4). While the current body of scientific knowledge offers conflicting evidence on the effectiveness of WBV in augmenting neuromuscular performance it is possible that WBV may result in alterations to specific aspects of the force-time curve during the performance of a maximal isometric contraction. Therefore, the primary purpose of this investigation was to examine the effects of WBV performed using 30 Hz frequency and 2-4 mm amplitude on the force-time curves of an isometric mid-thigh pull
    corecore