1,391 research outputs found
Role of walking-exercise therapy after stroke
Stroke commonly leads to reduced mobility, which leads to deconditioning and a worsening of vascular risk factors, such as diabetes. The worsened risk profile leads to further strokes and disability--a vicious cycle for the stroke survivor. Exercise (walking) therapy may break this cycle by providing adequate stimuli for improving gait through plastic adaptation in the brain and through increasing fitness. Randomized, controlled data demonstrate the efficacy for gains in fitness and walking speed, the latter being related to lasting changes in activation patterns of the brainstem and cerebellum. Diabetes and muscle inflammation can also be improved by aerobic exercise training. The scope of this review summarizes these data and identifies unresolved issues related to optimization, intensity and maintenance of therapy effects. Exercise should be an integral part of every rehabilitation program
Is keV ion induced pattern formation on Si(001) caused by metal impurities?
We present ion beam erosion experiments performed in ultra high vacuum using
a differentially pumped ion source and taking care that the ion beam hits the
Si(001) sample only. Under these conditions no ion beam patterns form on Si for
angles below 45 degrees with respect to the global surface normal using 2 keV
Kr ions and fluences of 2 x 10^22 ions/m^2. In fact, the ion beam induces a
smoothening of preformed patterns. Simultaneous sputter deposition of stainless
steel in this angular range creates a variety of patterns, similar to those
previously ascribed to clean ion beam induced destabilization of the surface
profile. Only for grazing incidence with incident angles between 60 degrees and
83 degrees pronounced ion beam patterns form. It appears that the angular
dependent stability of Si(001) against pattern formation under clean ion beam
erosion conditions is related to the angular dependence of the sputtering
yield, and not primarily to a curvature dependent yield as invoked frequently
in continuum theory models.Comment: 15 pages, 7 figures. This is an author-created, un-copyedited version
of an article published in Nanotechnology. IOP Publishing Ltd is not
responsible for any errors or omissions in this version of the manuscript or
any version derived from i
Stable isotope analysis of soft tissues from mummified human remains
Mummies are faunal remains that include the preservation of soft tissues, such as skin, muscle, nails and hair as well as bone. These soft tissues are generally rich in collagen or keratin proteins and thus provide potentially suitable material for stable isotope studies. When preserved, such tissues can provide high-resolution information about the diet and migration of humans in the weeks and months before death. Hair, nails and soft tissue provide short-term (months) dietary information in contrast to bone which will represent 5–20 years of dietary history prior to death, depending on the bone analysed. Such high-resolution data can answer questions on the season of death, seasonality of food resources and the movement and relocation of people. This review begins with a summary of the most common isotope techniques (13C/12C, 15N/14N) and the tissues concerned, followed by an analysis of the key questions that have been addressed using these methods. Until relatively recently work has focused on bulk protein isotope analysis, but in the last 10 years this has been expanded to on-line compound-specific amino acid analysis and to a wider variety of isotopes (18O/16O, 2H/1H and 34S/32S) and these applications are also discussed
Observation of an Excited Bc+ State
Using pp collision data corresponding to an integrated luminosity of 8.5 fb-1 recorded by the LHCb experiment at center-of-mass energies of s=7, 8, and 13 TeV, the observation of an excited Bc+ state in the Bc+π+π- invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(Bc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Bc+ mass. It is consistent with expectations of the Bc∗(2S31)+ state reconstructed without the low-energy photon from the Bc∗(1S31)+→Bc+γ decay following Bc∗(2S31)+→Bc∗(1S31)+π+π-. A second state is seen with a global (local) statistical significance of 2.2σ (3.2σ) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(Bc+) MeV/c2, and is consistent with the Bc(2S10)+ state. These mass measurements are the most precise to date
Bose-Einstein correlations of same-sign charged pions in the forward region in pp collisions at √s=7 TeV
Bose-Einstein correlations of same-sign charged pions, produced in protonproton collisions at a 7 TeV centre-of-mass energy, are studied using a data sample collected
by the LHCb experiment. The signature for Bose-Einstein correlations is observed in the
form of an enhancement of pairs of like-sign charged pions with small four-momentum
difference squared. The charged-particle multiplicity dependence of the Bose-Einstein correlation parameters describing the correlation strength and the size of the emitting source
is investigated, determining both the correlation radius and the chaoticity parameter. The
measured correlation radius is found to increase as a function of increasing charged-particle
multiplicity, while the chaoticity parameter is seen to decreas
Measurement of the inelastic pp cross-section at a centre-of-mass energy of 13TeV
The cross-section for inelastic proton-proton collisions at a centre-of-mass energy of 13TeV is measured with the LHCb detector. The fiducial cross-section for inelastic interactions producing at least one prompt long-lived charged particle with momentum p > 2 GeV/c in the pseudorapidity range 2 < η < 5 is determined to be ϭ acc = 62:2 ± 0:2 ± 2:5mb. The first uncertainty is the intrinsic systematic uncertainty of the measurement, the second is due to the uncertainty on the integrated luminosity. The statistical uncertainty is negligible. Extrapolation to full phase space yields the total inelastic proton-proton cross-section ϭ inel = 75:4 ± 3:0 ± 4:5mb, where the first uncertainty is experimental and the second due to the extrapolation. An updated value of the inelastic cross-section at a centre-of-mass energy of 7TeV is also reported
Measurement of the double- β decay of <sup>150</sup> Nd to the 0 1+ excited state of <sup>150</sup> Sm in NEMO-3
The NEMO-3 results for the double- β decay of 150 Nd to the 0 1+ and 2 1+ excited states of 150 Sm are reported. The data recorded during 5.25 year with 36.6 g of the isotope 150 Nd are used in the analysis. The signal of the 2 νββ transition to the 0 1+ excited state is detected with a statistical significance exceeding 5 σ . The half-life is measured to be T1/22νββ(01+)=[1.11-0.14+0.19(stat)-0.15+0.17(syst)]×1020 year, which is the most precise value that has been measured to date. 90% confidence-level limits are set for the other decay modes. For the 2 νββ decay to the 2 1+ level the limit is T1/22νββ(21+)>2.42×1020year . The limits on the 0 νββ decay to the 0 1+ and 2 1+ levels of 150 Sm are significantly improved to T1/20νββ(01+)>1.36×1022year and T1/20νββ(21+)>1.26×1022year
Promoter Polymorphisms in the Nitric Oxide Synthase 3 Gene Are Associated With Ischemic Stroke Susceptibility in Young Black Women
Endothelial nitric oxide exerts a variety of protective effects on endothelial cells and blood vessels, and therefore the nitric oxide synthase 3 gene (NOS3) is a logical candidate gene for stroke susceptibility
Motion processing with wide-field neurons in the retino-tecto-rotundal pathway
The retino-tecto-rotundal pathway is the main visual pathway in non-mammalian vertebrates and has been found to be highly involved in visual processing. Despite the extensive receptive fields of tectal and rotundal wide-field neurons, pattern discrimination tasks suggest a system with high spatial resolution. In this paper, we address the problem of how global processing performed by motion-sensitive wide-field neurons can be brought into agreement with the concept of a local analysis of visual stimuli. As a solution to this problem, we propose a firing-rate model of the retino-tecto-rotundal pathway which describes how spatiotemporal information can be organized and retained by tectal and rotundal wide-field neurons while processing Fourier-based motion in absence of periodic receptive-field structures. The model incorporates anatomical and electrophysiological experimental data on tectal and rotundal neurons, and the basic response characteristics of tectal and rotundal neurons to moving stimuli are captured by the model cells. We show that local velocity estimates may be derived from rotundal-cell responses via superposition in a subsequent processing step. Experimentally testable predictions which are both specific and characteristic to the model are provided. Thus, a conclusive explanation can be given of how the retino-tecto-rotundal pathway enables the animal to detect and localize moving objects or to estimate its self-motion parameters
Development of methods for the preparation of radiopure <sup>82</sup>Se sources for the SuperNEMO neutrinoless double-beta decay experiment
A radiochemical method for producing 82Se sources with an ultra-low level of contamination of natural radionuclides (40K, decay products of 232Th and 238U) has been developed based on cation-exchange chromatographic purification with reverse removal of impurities. It includes chromatographic separation (purification), reduction, conditioning (which includes decantation, centrifugation, washing, grinding, and drying), and 82Se foil production. The conditioning stage, during which highly dispersed elemental selenium is obtained by the reduction of purified selenious acid (H2SeO3) with sulfur dioxide (SO2) represents the crucial step in the preparation of radiopure 82Se samples. The natural selenium (600 g) was first produced in this procedure in order to refine the method. The technique developed was then used to produce 2.5 kg of radiopure enriched selenium (82Se). The produced 82Se samples were wrapped in polyethylene (12 μm thick) and radionuclides present in the sample were analyzed with the BiPo-3 detector. The radiopurity of the plastic materials (chromatographic column material and polypropylene chemical vessels), which were used at all stages, was determined by instrumental neutron activation analysis. The radiopurity of the 82Se foils was checked by measurements with the BiPo-3 spectrometer, which confirmed the high purity of the final product. The measured contamination level for 208Tl was 8-54 μBq/kg, and for 214Bi the detection limit of 600 μBq/kg has been reached.</p
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