4,850 research outputs found

    Evaluation of the Clinimetric Properties of the Upper Limb Subscales of the Motor Assessment Scale Using a Rasch Analysis Model.

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    OBJECTIVES: To apply Rasch analysis to evaluate the psychometric properties of the composite score of the 3 upper limb subscales of the Motor Assessment Scale (UL-MAS) when administered in the acute/subacute phase post-stroke. DESIGN: Prospective data collection of UL-MAS scores. PARTICIPANTS: Eighty Eighty individuals a mean of 64.8 days (standard deviation 53.3; range 4-193 days) following the onset of unilateral stroke. METHODS: All UL-MAS test items were administered in 30 participants assessed longitudinally over 3 occasions, and in 50 participants assessed on a single occasion. These 140 observations were pooled to be evaluated using Rasch analysis. RESULTS: With the elimination of the wrist radial deviation test item, the UL-MAS demonstrated uni-dimensionality with no significant test item response bias. The test item difficulty hierarchy was validated in the Upper Arm and Hand Movements subscales, but not in the Advanced Hand Activities subscale. The acceptable floor (14%) and ceiling (9%) effects and the high Person Separation Reliability Index (0.96) indicated that the scale was appropriately targeted to discriminate statistically between groups of acute/subacute stroke participants with differing upper limb motor recovery. CONCLUSION: The findings support the psychometric properties of the composite UL-MAS score in this clinical population

    Household decision-making about delivery in health facilities: evidence from Tanzania.

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    This study investigated how partners' perceptions of the healthcare system influence decisions about delivery-location in low-resource settings. A multistage population-representative sample was used in Kasulu district, Tanzania, to identify women who had given birth in the last five years and their partners. Of 826 couples in analysis, 506 (61.3%) of the women delivered in the home. In multivariate analysis, factors associated with delivery in a health facility were agreement of partners on the importance of delivering in a health facility and agreement that skills of doctors are better than those of traditional birth attendants. When partners disagreed, the opinion of the woman was more influential in determining delivery-location. Agreement of partners regarding perceptions about the healthcare system appeared to be an important driver of decisions about delivery-location. These findings suggest that both partners should be included in the decision-making process regarding delivery to raise rates of delivery at facility

    Searching for Dark Matter at the LHC with a Mono-Z

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    We investigate a mono-Z process as a potential dark matter search strategy at the LHC. In this channel a single Z boson recoils against missing transverse momentum, attributed to dark matter particles, χ\chi, which escape the detector. This search strategy is related, and complementary to, monojet and monophoton searches. For illustrative purposes we consider the process qqˉ−>χχZq\bar{q} -> \chi\chi Z in a toy dark matter model, where the Z boson is emitted from either the initial state quarks, or from the internal propagator. Among the signatures of this process will be a pair of muons with high pT that reconstruct to the invariant mass of the Z, and large amounts of missing transverse energy. Being a purely electroweak signal, QCD and other Standard Model backgrounds are relatively easily removed with modest selection cuts. We compare the signal to Standard Model backgrounds and demonstrate that, even for conservative cuts, there exist regions of parameter space where the signal may be clearly visible above background in future LHC data, allowing either new discovery potential or the possibility of supplementing information about the dark sector beyond that available from other observable channels.Comment: 11 pages, 13 figure

    Gas Purity effect on GEM Performance in He and Ne at Low Temperatures

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    The performance of Gas Electron Multipliers (GEMs) in gaseous He, Ne, He+H2 and Ne+H2 was studied at temperatures in the range of 3-293 K. This paper reports on previously published measurements and additional studies on the effects of the purity of the gases in which the GEM performance is evaluated. In He, at temperatures between 77 and 293 K, triple-GEM structures operate at rather high gains, exceeding 1000. There is an indication that this high gain is achieved through the Penning effect as a result of impurities in the gas. At lower temperatures the gain-voltage characteristics are significantly modified probably due to the freeze-out of these impurities. Double-GEM and single-GEM structures can operate down to 3 K at gains reaching only several tens at a gas density of about 0.5 g/l; at higher densities the maximum gain drops further. In Ne, the maximum gain also drops at cryogenic temperatures. The gain drop in Ne at low temperatures can be re-established in Penning mixtures of Ne+H2: very high gains, exceeding 104, have been obtained in these mixtures at 30-77 K, at a density of 9.2 g/l which corresponds to saturated Ne vapor density at 27 K. The addition of small amounts of H2 in He also re-establishes large GEM gains above 30 K but no gain was observed in He+H2 at 4 K and a density of 1.7 g/l (corresponding to roughly one-tenth of the saturated vapor density). These studies are, in part, being pursued in the development of two-phase He and Ne detectors for solar neutrino detection.Comment: 4 pages, 7 figure

    Laterality Differences in Cerebellar-Motor Cortex Connectivity

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    Lateralization of function is an important organizational feature of the motor system. Each effector is predominantly controlled by the contralateral cerebral cortex and the ipsilateral cerebellum. Transcranial magnetic stimulation studies have revealed hemispheric differences in the stimulation strength required to evoke a muscle response from the primary motor cortex (M1), with the dominant hemisphere typically requiring less stimulation than the nondominant. The current study assessed whether the strength of the connection between the cerebellum and M1 (CB-M1), known to change in association with motor learning, have hemispheric differences and whether these differences have any behavioral correlate. We observed, in right-handed individuals, that the connection between the right cerebellum and left M1 is typically stronger than the contralateral network. Behaviorally, we detected no lateralized learning processes, though we did find a significant effect on the amplitude of reaching movements across hands. Furthermore, we observed that the strength of the CB-M1 connection is correlated with the amplitude variability of reaching movements, a measure of movement precision, where stronger connectivity was associated with better precision. These findings indicate that lateralization in the motor system is present beyond the primary motor cortex, and points to an association between cerebellar M1 connectivity and movement execution
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