257 research outputs found

    Measures of neuropsychological assessment as indicators of success in neuropsychological rehabilitation: an exploratory correlational study

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    Neuropsychological assessment not only allows diagnosing possible neurocognitive impairments in domains such as attention, working memory, and executive functions, but can also provide useful information for the neuropsychological rehabilitation. By applying a set of valid neuropsychological tests to individuals with Acquired Brain Injury (ABI), and subsequently studying how patients’ performance in rehabilitation programs relates with measures that are commonly provided by these tests, we may obtain valuable predictors of individual success that can be considered in neuropsychological rehabilitation.info:eu-repo/semantics/publishedVersio

    Roughness of Sandpile Surfaces

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    We study the surface roughness of prototype models displaying self-organized criticality (SOC) and their noncritical variants in one dimension. For SOC systems, we find that two seemingly equivalent definitions of surface roughness yields different asymptotic scaling exponents. Using approximate analytical arguments and extensive numerical studies we conclude that this ambiguity is due to the special scaling properties of the nonlinear steady state surface. We also find that there is no such ambiguity for non-SOC models, although there may be intermediate crossovers to different roughness values. Such crossovers need to be distinguished from the true asymptotic behaviour, as in the case of a noncritical disordered sandpile model studied in [10].Comment: 5 pages, 4 figures. Accepted for publication in Phys. Rev.

    Major electrocardiographic abnormalities according to the Minnesota coding system among Brazilian adults (from the ELSA-Brasil cohort study)

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    The electrocardiogram is a simple and useful clinical tool; nevertheless, few studies have evaluated the prevalence of electrocardiographic abnormalities in the Latin American population. This study aims to evaluate the major electrocardiographic abnormalities according to the Minnesota coding system in Brazilian adults, stratified by gender, age, race, and cardiovascular risk factors. Data from 14,424 adults (45.8% men, age 35 to 74 years) were obtained at baseline of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil), according to standardized protocol. The electrocardiogram were obtained with the Burdick Atria 6100 machine, stored on Pyramis System, automatically coded according to the Minnesota coding system by the Glasgow University software and then manually revised. Major abnormalities were more prevalent in men than women (11.3% and 7.9%, p <0.001). These differences were consistent through the different age groups, race, and number of cardiovascular risk factors. Electrocardiographic major abnormalities were more prevalent in black participants for both men (black: 15.1%, mixed: 10.4%, white: 11.1%, p = 0.001) and women (black: 10%, mixed: 7.6%, white: 7.2%, p = 0.004). In conclusion, in this large sample of Brazilian adults, the prevalence of major electrocardiographic abnormalities was higher among men, the elderly, black, and among people with more cardiovascular risk factors

    Pseudofractal Scale-free Web

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    We find that scale-free random networks are excellently modeled by a deterministic graph. This graph has a discrete degree distribution (degree is the number of connections of a vertex) which is characterized by a power-law with exponent γ=1+ln3/ln2\gamma=1+\ln3/\ln2. Properties of this simple structure are surprisingly close to those of growing random scale-free networks with γ\gamma in the most interesting region, between 2 and 3. We succeed to find exactly and numerically with high precision all main characteristics of the graph. In particular, we obtain the exact shortest-path-length distribution. For the large network (lnN1\ln N \gg 1) the distribution tends to a Gaussian of width lnN\sim \sqrt{\ln N} centered at ˉlnN\bar{\ell} \sim \ln N. We show that the eigenvalue spectrum of the adjacency matrix of the graph has a power-law tail with exponent 2+γ2+\gamma.Comment: 5 pages, 3 figure

    Tsallis non-extensive statistics, intermittent turbulence, SOC and chaos in the solar plasma. Part one: Sunspot dynamics

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    In this study, the nonlinear analysis of the sunspot index is embedded in the non-extensive statistical theory of Tsallis. The triplet of Tsallis, as well as the correlation dimension and the Lyapunov exponent spectrum were estimated for the SVD components of the sunspot index timeseries. Also the multifractal scaling exponent spectrum, the generalized Renyi dimension spectrum and the spectrum of the structure function exponents were estimated experimentally and theoretically by using the entropy principle included in Tsallis non extensive statistical theory, following Arimitsu and Arimitsu. Our analysis showed clearly the following: a) a phase transition process in the solar dynamics from high dimensional non Gaussian SOC state to a low dimensional non Gaussian chaotic state, b) strong intermittent solar turbulence and anomalous (multifractal) diffusion solar process, which is strengthened as the solar dynamics makes phase transition to low dimensional chaos in accordance to Ruzmaikin, Zeleny and Milovanov studies c) faithful agreement of Tsallis non equilibrium statistical theory with the experimental estimations of i) non-Gaussian probability distribution function, ii) multifractal scaling exponent spectrum and generalized Renyi dimension spectrum, iii) exponent spectrum of the structure functions estimated for the sunspot index and its underlying non equilibrium solar dynamics.Comment: 40 pages, 11 figure

    Perturbations of brane worlds

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    We consider cosmological models where the universe, governed by Einstein's equations, is a piece of a five dimensional double-sided anti-de Sitter spacetime (that is, a "Z2Z_2-symmetric bulk") with matter confined to its four dimensional Robertson-Walker boundary or "brane". We study the perturbations of such models. We use conformally minkowskian coordinates to disentangle the contributions of the bulk gravitons and of the motion of the brane. We find the restrictions put on the bulk gravitons when matter on the brane is taken to be a scalar field and we solve in that case the brane perturbation equations.Comment: 19 pages, no figures, RevTex, version to appear in Phys.Rev.D; minor changes in chap.V, polarisation tensor at page 13 correcte
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