8,319 research outputs found

    Determination of step rate thresholds corresponding to physical activity intensity classifications in adults

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    Current recommendations call for adults to be physically active at moderate and/or vigorous intensities. Given the popularity of walking and running, the use of step rates may provide a practical and inexpensive means to evaluate ambulatory intensity. Thus, the purpose of this study was to identify step rate thresholds that correspond to various intensity classifications. Methods: Oxygen consumption was measured at rest and during 10 minute treadmill walking and running trials at 6 standardized speeds (54, 80, 107, 134, 161, and 188 m∙min-1) in 9 men and 10 women (28.8 ± 6.8 yrs). Two observers counted the participants’ steps at each treadmill speed. Linear and nonlinear regression analyses were used to develop prediction equations to ascertain step rate thresholds at various intensities. Results: Nonlinear regression analysis of the metabolic cost versus step rates across all treadmill speeds yielded the highest R2 values for men (R2 = .91) and women (R2 = .79). For men, the nonlinear analysis yielded 94 and 125 step∙min-1 for moderate and vigorous intensities, respectively. For women, 99 and 135 step∙min-1 corresponded with moderate and vigorous intensities, respectively. Conclusions: Promoting a step rate of 100 step∙min-1 may serve as a practical public health recommendation to exercise at moderate intensity

    The H II Region/PDR Connection: Self-Consistent Calculations of Physical Conditions in Star-Forming Regions

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    We have performed a series of calculations designed to reproduce infrared diagnostics used to determine physical conditions in star forming regions. We self-consistently calculate the thermal and chemical structure of an H II region and photodissociation region (PDR) that are in pressure equilibrium. This differs from previous work, which used separate calculations for each gas phase. Our calculations span a wide range of stellar temperatures, gas densities, and ionization parameters. We describe improvements made to the spectral synthesis code Cloudy that made these calculations possible. These include the addition of a molecular network with ~1000 reactions involving 68 molecular species and improved treatment of the grain physics. Data from the Spitzer First Look Survey, along with other archives, are used to derive important physical characteristics of the H II region and PDR. These include stellar temperatures, electron densities, ionization parameters, UV radiation flux, and PDR density. Finally, we calculate the contribution of the H II region to PDR emission line diagnostics, which allows for a more accurate determination of physical conditions in the PDR.Comment: 60 pages, 35 figures, to be published in the Astrophysical Journal. Version with full resolution is available at http://www.pa.uky.edu/~nicholas/hii_pdr_high_res.pd

    Direct multiscale coupling of a transport code to gyrokinetic turbulence codes

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    Direct coupling between a transport solver and local, nonlinear gyrokinetic calculations using the multiscale gyrokinetic code TRINITY [M. Barnes, Ph.D. thesis, arxiv:0901.2868] is described. The coupling of the microscopic and macroscopic physics is done within the framework of multiscale gyrokinetic theory, of which we present the assumptions and key results. An assumption of scale separation in space and time allows for the simulation of turbulence in small regions of the space-time grid, which are embedded in a coarse grid on which the transport equations are implicitly evolved. This leads to a reduction in computational expense of several orders of magnitude, making first-principles simulations of the full fusion device volume over the confinement time feasible on current computing resources. Numerical results from TRINITY simulations are presented and compared with experimental data from JET and ASDEX Upgrade plasmas.Comment: 12 pages, 13 figures, invited paper for 2009 APS-DPP meeting, submitted to Phys. Plasma

    Multiscale Gyrokinetics for Rotating Tokamak Plasmas: Fluctuations, Transport and Energy Flows

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    This paper presents a complete theoretical framework for plasma turbulence and transport in tokamak plasmas. The fundamental scale separations present in plasma turbulence are codified as an asymptotic expansion in the ratio of the gyroradius to the equilibrium scale length. Proceeding order-by-order in this expansion, a framework for plasma turbulence is developed. It comprises an instantaneous equilibrium, the fluctuations driven by gradients in the equilibrium quantities, and the transport-timescale evolution of mean profiles of these quantities driven by the fluctuations. The equilibrium distribution functions are local Maxwellians with each flux surface rotating toroidally as a rigid body. The magnetic equillibrium is obtained from the Grad-Shafranov equation for a rotating plasma and the slow (resistive) evolution of the magnetic field is given by an evolution equation for the safety factor q. Large-scale deviations of the distribution function from a Maxwellian are given by neoclassical theory. The fluctuations are determined by the high-flow gyrokinetic equation, from which we derive the governing principle for gyrokinetic turbulence in tokamaks: the conservation and local cascade of free energy. Transport equations for the evolution of the mean density, temperature and flow velocity profiles are derived. These transport equations show how the neoclassical corrections and the fluctuations act back upon the mean profiles through fluxes and heating. The energy and entropy conservation laws for the mean profiles are derived. Total energy is conserved and there is no net turbulent heating. Entropy is produced by the action of fluxes flattening gradients, Ohmic heating, and the equilibration of mean temperatures. Finally, this framework is condensed, in the low-Mach-number limit, to a concise set of equations suitable for numerical implementation.Comment: 113 pages, 3 figure

    Rare kaon decays in SUSY with non-universal A terms

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    We study the rare kaon decays in the framework of general SUSY models. Unlike the results in the literature, we find the contributions from the gluino exchange to the branching ratio of K+→π+ννˉK^+\to \pi^+ \nu \bar{\nu} can reach the central value (∼1.5×10−10\sim 1.5 \times 10^{-10}) of the new E787 data while the predicted value of standard model is less than 10−1010^{-10}. We also find that the same effects also enhance the decays of KL→π0ννˉK_{L}\to \pi^0 \nu \bar{\nu}, KL→π0e+e−K_L\to\pi^0e^{+} e^{-} and KL→μ+μ−K_L\to\mu^+ \mu^-.Comment: 9 pages, references added, revised version to appear in J. Phys.

    Effectiveness of Management of Change in an Organization (Case of Kenya Power Ltd, Central Rift, Nakuru County)

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    Change is inevitable in business life and business that fails to change is doomed to extinction Marcus (2011). Efforts of implementation of change management in organisations very often fail, most of the transformation efforts undertaken in firms end up with a failure, producing only disappointment, frustration, burned-out and scared employees, and waste of resources. The objective of the research was to find the effective and efficient ways of implementing change management obtain useful solutions for practitioners and new knowledge for scholars and managers. The objectives include,to establish the extent to which the organization plan for implementation of change management,to find out the significance of education and training on the implementation of change management in an organization, to examine how the organization deals with resistance to change management  implementation. The target population was1057 employees of which 857 are employees of Kenya power and 200 Kenya power contracted companies employees in Central Rift Region Nakuru county. Research utilized stratified random sampling to select 265 employees and contractor for the study. Self administered Questionnaires were used to collect the data.  The cording system was inco-operated in the Statistical Package for Social Science (SPSS) data analysis software and Ms –Excel The data was collected and analysed by use of both descriptive statistics. Percentages mode median and means calculated from responses to questionnaire. The study established that Kenya Power Ltd was able to sustain change in its operations leading to service delivery but was unable to achieve employees’ satisfaction and the desired goal of changing organization culture in spite of changing the organization name through restructuring

    Five-dimensional Monopole Equation with Hedge-Hog Ansatz and Abel's Differential Equation

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    We review the generalized monopole in the five-dimensional Euclidean space. A numerical solution with the Hedge-Hog ansatz is studied. The Bogomol'nyi equation becomes a second order autonomous non-linear differential equation. The equation can be translated into the Abel's differential equation of the second kind and is an algebraic differential equation.Comment: 4 pages, 4 figures, typos correcte
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