6,380 research outputs found

    Spectral Properties of H-Reflex Recordings After an Acute Bout of Whole-Body Vibration

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    Although research supports the use of whole-body vibration (WBV) to improve neuromuscular performance, the mechanisms for these improvements remain unclear. The purpose of this study was to identify the effect ofWBV on the spectral properties of electrically evoked H-reflex recordings in the soleus (SOL) muscle. The H-reflex recordings were measured in the SOL muscle of 20 participants before and after a bout of WBV. The H-reflexes were evoked every 15 seconds for 150 seconds after WBV. A wavelet procedure was used to extract spectral data, which were then quantified with a principle components analysis. Resultant principle component scores were used for statistical analysis. The analysis extracted 1 principle component associated with the intensity of the myoelectric spectra and 1 principle component associated with the frequency. The scores of the principle component that were related to the myoelectric intensity were smaller at 30 and 60 milliseconds after WBV than before WBV. The WBV transiently decreased the intensity of myoelectric spectra during electrically evoked contractions, but it did not influence the frequency of the spectra. The decrease in intensity likely indicates a smaller electrically evoked muscle twitch response, whereas the lack of change in frequency would indicate a similar recruitment pattern of motor units before and after WBV

    The Anomalous Magnetic Moments of the Electron and the Muon - Improved QED Predictions Using Pade Approximants

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    We use Pade Approximants to obtain improved predictions for the anomalous magnetic moments of the electron and the muon. These are needed because of the very precise experimental values presently obtained for the electron, and soon to be obtained at BNL for the muon. The Pade prediction for the QED contribution to the anomalous magnetic moment of the muon differs significantly from the naive perturbative prediction.Comment: 8 pages (LateX); SLAC-PUB-6670, CERN-TH-7451/94, TAUP-2201-94, OSU-RN-393/94. Typo correcte

    A Relationship of Trust: Are State ?School Trust Lands? Being Prudently Managed for the Beneficiary?

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    Every state entering the Union in the United States since 1803 received land grants from the federal government for the support of their public schools. Inherent in this federal grant is the fiduciary duty to prudently and effectively manage trust assets for the beneficiary, their school systems. This paper addresses the question of whether managers of trust lands are meeting their fiduciary responsibilities of ??maximum economic benefit?? for their beneficiaries. Realized market value-based economic returns from grazing lease revenues and capital appreciation for all twenty-three counties in Wyoming are compared with returns that may have been generated from alternative investment policy alternatives. Market values and capital appreciation for school trust lands in Wyoming are estimated from hedonic models formulated from ranch sales data and grazing revenue data.

    A Prediction for the 4-Loop \beta Function

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    We predict that the four-loop contribution \beta_3 to the QCD \beta function in the MS-bar prescription is given by \beta_3\simeq 23,600(900) - 6,400(200) N_f + 350(70) N_f^2 + 1.5 N_f^3, where N_f is the number of flavours and the coefficient of N_f^3 is an exact result from large-N_f expansion. In the phenomenologically-interesting case N_f=3, we estimate \beta_3 = (7.6 \pm 0.1) x 10^3. We discuss our estimates of the errors in these QCD predictions, basing them on the demonstrated accuracy of our method in test applications to the O(N) \Phi^4 theory, and on variations in the details of our estimation method, which goes beyond conventional Pade approximants by estimating and correcting for subasymptotic deviations from exact results.Comment: 11 pages, LaTeX, including 2 figures in 3 ps files; requires epsfig.sty; added comparison with recent exact result

    Use of accounting information in governmental regulation and public administration: The impact of John R. Commons and early institutional economists

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    This paper examines the socio-political process by which an ensemble of such calculative practices and techniques as accounting came to be developed, adopted, and justified within turn-of-the-cen-tury public administration. We are particularly concerned with examining the influence of John R. Commons and other early institutional economists during this Progressive era. Using primary and secondary archival materials, our purpose is to make three main contributions to the literature. First, the paper explores Commons\u27 contribution to the debates over value which seems to be somewhat unique in that he explicitly recognized that there exists no unproblematic, intrinsic measure of value, but rather that it must be socially constituted as reasonable with reference to common law. To illustrate this point, this paper explores Commons\u27 role in the historical development and implementation of rate of return regulation for utilities. Second, the paper describes the contradictory role accounting played during this period in ostensibly fostering administrative objectivity while accommodating a more pragmatic rhetoric of realpolitik in its development and deployment. The third contribution is to establish a linkage between current work in economics and accounting concerned with utility regulation and the debates of ninety years ago, noting that Commons\u27 contribution has not been fully explored or recognized within the accounting literature

    Hydroacoustic evaluation of spawning red hind (Epinephelus guttatus) aggregations along the coast of Puerto Rico in 2002 and 2003

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    Red hind (Epinephelus guttatus) have been overfished in the Caribbean and were included with seven other regional grouper species deemed vulnerable to risk of extinction. The Puerto Rico Department of Natural and Environmental Resources desired to map spawning red hind aggregations within commonwealth waters as part of their resource management program for the species. Mobile hydroacoustic surveys were conducted over 3-day periods in 2002 and 2003, indexed to the full moon phase in February or March when red hind were known to aggregate. Four vessels concurrently sampled the southwest, south, and southeast coasts of Puerto Rico in 2002. In 2003, three vessels conducted complementary surveys of the northwest, north, and northeast coasts of the island, completing a circuit of the coastal shelf-spawning habitat. These surveys indicated that red hind spawning aggregations were prevalent along the south and west coasts, and sparse along the north coast during the survey periods. Highest spawning red hind concentrations were observed in three areas offshore of the west coast of Puerto Rico, around Mona and Desecheo islands (20,443 and 10,559 fish/km2, respectively) and in the Bajo de Cico seasonal closed area (4,544 fish/km2). Following both 2002 and 2003 surveys, a series of controlled acoustic measurements of known local fish species in net pens were conducted to assess the mean target strength (acoustic backscatter) of each group. Ten species of fish were measured, including red hind (E. guttatus), coney (E. fulvus), white grunt (Haemulon plumieri), pluma (Calamus pennatula), blue tang (Acanthurus coeruleus), squirrel fish (Holocentrus spp.), black durgeon (Melichtyhs niger), ocean file fish (Canthidermis sufflamen), ocean surgeon fish (Acanthurus bahianus), and butter grouper (Mycteroperca spp.). In general, the mean target strength results from the caged fish experiments were in agreement with published target strength length relationships, with the exception of white grunt and pluma

    Clustering South African households based on their asset status using latent variable models

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    The Agincourt Health and Demographic Surveillance System has since 2001 conducted a biannual household asset survey in order to quantify household socio-economic status (SES) in a rural population living in northeast South Africa. The survey contains binary, ordinal and nominal items. In the absence of income or expenditure data, the SES landscape in the study population is explored and described by clustering the households into homogeneous groups based on their asset status. A model-based approach to clustering the Agincourt households, based on latent variable models, is proposed. In the case of modeling binary or ordinal items, item response theory models are employed. For nominal survey items, a factor analysis model, similar in nature to a multinomial probit model, is used. Both model types have an underlying latent variable structure - this similarity is exploited and the models are combined to produce a hybrid model capable of handling mixed data types. Further, a mixture of the hybrid models is considered to provide clustering capabilities within the context of mixed binary, ordinal and nominal response data. The proposed model is termed a mixture of factor analyzers for mixed data (MFA-MD). The MFA-MD model is applied to the survey data to cluster the Agincourt households into homogeneous groups. The model is estimated within the Bayesian paradigm, using a Markov chain Monte Carlo algorithm. Intuitive groupings result, providing insight to the different socio-economic strata within the Agincourt region.Comment: Published in at http://dx.doi.org/10.1214/14-AOAS726 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org
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