465 research outputs found

    Lacunar infarcts, depression and anxiety symptoms one year after stroke

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    Background: Mood disorders are frequent after stroke and are associated with poorer quality of life. Previous studies have reported conflicting results as to stroke subtype in the incidence of poststroke mood disorders. We explored the relationship between subcortical ischemic stroke subtype (lacunar) and presence of such symptoms at 1 year after stroke. Methods: Anonymized data were accessed from the Virtual International Stroke Trials Archive. Stroke subtypes were classified according to the Trial of Org 10172 in Acute Stroke Treatment classification. Depression and anxiety symptoms were assessed using Hospital Anxiety and Depression Scale. We investigated independent predictors of depression and anxiety symptoms using a logistic regression model. Results: Data were available for 2160 patients. Almost one fifth of the patients developed both anxiety and depression at 1-year follow-up. After adjusting for confounders, the lacunar subtype was least associated with both anxiety (odds ratio [OR] = .61; 95% confidence interval [CI] = .46-.80) and depression symptoms (OR = .71; CI = .55-.93) versus other stroke subtypes. Conclusions: Lacunar strokes have a weaker association with presence of anxiety and depression symptoms compared with other subtypes

    Primer reporte de albinismo en vizcacha Lagidium viscacia (Rodentia: Chinchillidae) en los Andes de Perú

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    We report the first record of albinism in vizcacha (Lagidium viscacia) based on two adult individuals sighted in department of Apurímac, in Peru. This record represents the first report of albinism in Chinchillidae.Se documenta el primer registro de albinismo de vizcacha (Lagidium viscacia) con base en dos individuos avistados en el departamento de Apurímac, en Perú. Este registro representa el primer reporte de albinismo en la familia Chinchillidae

    Measurement of the Target-Normal Single-Spin Asymmetry in Quasielastic Scattering from the Reaction He-3(up arrow) (e,e \u27)

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    We report the first measurement of the target single-spin asymmetry, A(y), in quasielastic scattering from the inclusive reaction He-3(up arrow)(e,e\u27) on a He-3 gas target polarized normal to the lepton scattering plane. Assuming time-reversal invariance, this asymmetry is strictly zero for one-photon exchange. A nonzero A(y) can arise from the interference between the one-and two-photon exchange processes which is sensitive to the details of the substructure of the nucleon. An experiment recently completed at Jefferson Lab yielded asymmetries with high statistical precision at Q(2) = 0.13, 0.46, and 0.97 GeV2. These measurements demonstrate, for the first time, that the He-3 asymmetry is clearly nonzero and negative at the 4 sigma-9 sigma level. Using measured proton-to-He-3 cross-section ratios and the effective polarization approximation, neutron asymmetries of -(1-3)% were obtained. The neutron asymmetry at high Q(2) is related to moments of the generalized parton distributions (GPDs). Our measured neutron asymmetry at Q(2) = 0.97 GeV2 agrees well with a prediction based on two-photon exchange using a GPD model and thus provides a new, independent constraint on these distributions

    A Large-Scale FPGA-Based Trigger and Dead-Time Free DAQ System for the Kaos Spectrometer at MAMI

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    The Kaos spectrometer is maintained by the A1 collaboration at the Mainz Microtron MAMI with a focus on the study of (e,e'K^+) coincidence reactions. For its electron-arm two vertical planes of fiber arrays, each comprising approximately 10 000 fibers, are operated close to zero degree scattering angle and in close proximity to the electron beam. A nearly dead-time free DAQ system to acquire timing and tracking information has been installed for this spectrometer arm. The signals of 144 multi-anode photomultipliers are collected by 96-channel front-end boards, digitized by double-threshold discriminators and the signal time is picked up by state-of-the-art F1 time-to-digital converter chips. In order to minimize background rates a sophisticated trigger logic was implemented in newly developed Vuprom modules. The trigger performs noise suppression, signal cluster finding, particle tracking, and coincidence timing, and can be expanded for kinematical matching (e'K^+) coincidences. The full system was designed to process more than 4 000 read-out channels and to cope with the high electron flux in the spectrometer and the high count rate requirement of the detectors. It was successfully in-beam tested at MAMI in 2009.Comment: Contributed to 17th IEEE Real Time Conference (RT10), Lisbon, 24-28 May 201

    Recoil polarization and beam-recoil double polarization measurement of \eta electroproduction on the proton in the region of the S_{11}(1535) resonance

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    The beam-recoil double polarization P_{x'}^h and P_{z'}^h and the recoil polarization P_{y'} were measured for the first time for the p(\vec{e},e'\vec{p})\eta reaction at a four-momentum transfer of Q^2=0.1 GeV^2/c^2 and a center of mass production angle of \theta = 120^\circ at MAMI C. With a center of mass energy range of 1500 MeV < W < 1550 MeV the region of the S_{11}(1535) and D_{13}(1520) resonance was covered. The results are discussed in the framework of a phenomenological isobar model (Eta-MAID). While P_{x'}^h and P_{z'}^h are in good agreement with the model, P_{y'} shows a significant deviation, consistent with existing photoproduction data on the polarized-target asymmetry.Comment: 4 pages, 1 figur

    Search for Light Gauge Bosons of the Dark Sector at the Mainz Microtron

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    A new exclusion limit for the electromagnetic production of a light U(1) gauge boson {\gamma}' decaying to e^+e^- was determined by the A1 Collaboration at the Mainz Microtron. Such light gauge bosons appear in several extensions of the standard model and are also discussed as candidates for the interaction of dark matter with standard model matter. In electron scattering from a heavy nucleus, the existing limits for a narrow state coupling to e^+e^- were reduced by nearly an order of magnitude in the range of the lepton pair mass of 210 MeV/c^2 < m_e^+e^- < 300 MeV/c^2. This experiment demonstrates the potential of high current and high resolution fixed target experiments for the search for physics beyond the standard model.Comment: 4 pages, 7 figure

    New detectors for the kaon and hypernuclear experiments with KaoS at MAMI and with PANDA at GSI

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    The KaoS spectrometer at the Mainz Microtron MAMI, Germany, is perceived as the ideal candidate for a dedicated spectrometer in kaon and hypernuclei electroproduction. KaoS will be equipped with new read-out electronics, a completely new focal plane detector package consisting of scintillating fibres, and a new trigger system. First prototypes of the fibre detectors and the associated new front-end electronics are shown in this contribution. The Mainz hypernuclei research program will complement the hypernuclear experiments at the planned FAIR facility at GSI, Germany. At the proposed antiproton storage ring the spectroscopy of double Lambda hypernuclei is one of the four main topics which will be addressed by the PANDA Collaboration. The experiments require the operation of high purity germanium (HPGe) detectors in high magnetic fields (B= 1T) in the presence of a large hadronic background. The performance of high resolution Ge detectors in such an environment has been investigated.Comment: Presentation at International Symposium on the Development of Detectors for Particle, Astroparticle and Synchrotron Radiation Experiments, Stanford, Ca (SNIC06), 6 pages, LaTeX, 11 eps figure

    Measurements of the \gamma * p --> \Delta(1232) reaction at low Q2

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    We report new p(e,ep)π(\vec{e},e^\prime p)\pi^\circ measurements in the Δ+(1232)\Delta^{+}(1232) resonance at the low momentum transfer region utilizing the magnetic spectrometers of the A1 Collaboration at MAMI. The mesonic cloud dynamics are predicted to be dominant and appreciably changing in this region while the momentum transfer is sufficiently low to be able to test chiral effective calculations. The results disagree with predictions of constituent quark models and are in reasonable agreement with dynamical calculations with pion cloud effects, chiral effective field theory and lattice calculations. The reported measurements suggest that improvement is required to the theoretical calculations and provide valuable input that will allow their refinements
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