186 research outputs found

    Boussinesq Solitons as Propagators of Neural Signals

    Get PDF
    We  consider  certain  approximation for determining the  equation  of motion  for nerve  signals by  using  the  model  of the  lipid  melting  of membranes.   The  nerve  pulses  are  found  to  display nonlinearity and  dispersion  during  the  melting  transition.  In this  simplified model the  nonlinear equation  early  proposed  by  Heimburg  and  coworkers  transformed to  the  well known  integrable Boussinesq  non linear  equation.   Under  specific values of the  parametric space this  system  shows the  existence  of singular  and  regular  soliton  like structures.   After  their  collisions  the  mutual creation  and annihilation (each other)  of nerve signals along the  nerve,  during  their  propagation, has been observed.Keywords: Boussinesq equation,  singular  solitons,  single neurons,  neural  code

    Potencial antifúngico de substâncias vegetais à Moniliophthora perniciosa.

    Get PDF
    Este trabalho teve como objetivo a avaliação da fungitoxicidade in vitro de substâncias de origem vegetal a M. perniciosa

    Sistema de informação para rastreamento de pescado.

    Get PDF
    A rastreabilidade de peixes confere segurança para quem compra ou comercializa o pescado. Para que seja possível esta rastreabilidade ser usada pela sociedade, é necessário que exista algum repositório de dados que contenha, por exemplo, todo o histórico do pescado, tais como espécie, procedência, manejo, análise físico-química, biológica e microbiológica da água, características diversas relacionadas à carne e couro, e vários outros dados. Com isto, podem ser conhecidas várias características, incluindo a rastreabilidade, para se decidir sobre compra e venda de pescados de qualidade. Para atender a esta demanda, foi desenvolvido um sistema de informações de rastreabilidade relativas a diversos tipos de peixes; desta forma, o objetivo deste trabalho é demonstrar este sistema, que poderá ser usado livremente por qualquer usuário.ReCIP 2011

    Darboux coordinates for (first order) tetrad gravity

    Full text link
    The Hamiltonian form of the Hilbert action in the first order tetrad formalism is examined. We perform a non-linear field redefinition of the canonical variables isolating the part of the spin connection which is canonically conjugate to the tetrad. The geometrical meaning of the constraints written in these new variables is examined.Comment: 12 pages, Latex. Minor presentation changes and some references added. Version to appear in Classical and Quantum Gravit

    The effect of changes in air humidity on historic tapestries

    Get PDF
    Historic tapestries are textile artworks usually found hanging inside historic buildings. They form part of the European heritage have been exposed for centuries to diverse environmental conditions some of which have permanently damaged them. To inform better appropriate conservation practices, their physical behavior when exposed to environmental changes must be understood. The research conducted aimed to assess how the internal environment conditions in a historic building affects the tapestries’ structures and produce change in their strain. For this a series of experiments on a historic 19th century tapestry inside an environmental chamber carried out and cycles of moisture adsorption and desorption tested. Digital Image Correlation (DIC) and magnetic sensors developed by were used to test successive stages of expansion and retraction of the tapestry given different levels of relative humidity (RH) in the environment

    Remarks on Resonant Scalars in the AdS/CFT Correspondence

    Get PDF
    The special properties of scalars having a mass such that the two possible dimensions of the dual scalar respect the unitarity and the Breitenlohner-Freedman bounds and their ratio is integral (``resonant scalars'') are studied in the AdS/CFT correspondence. The role of logarithmic branches in the gravity theory is related to the existence of a trace anomaly and to a marginal deformation in the Conformal Field Theory. The existence of asymptotic charges for the conformal group in the gravity theory is interpreted in terms of the properties of the corresponding CFT.Comment: 16 pages, 1 figur

    Counterterms and dual holographic anomalies in CS gravity

    Full text link
    The holographic Weyl anomaly associated to Chern-Simons gravity in 2n+1 dimensions is proportional to the Euler term in 2n dimensions, with no contributions from the Weyl tensor. We compute the holographic energy-momentum tensor associated to Chern-Simons gravity directly from the action, in an arbitrary odd-dimensional spacetime. We show, in particular, that the counterterms rendering the action finite contain only terms of the Lovelock type.Comment: 10 pages, no figure

    Accuracy of different handgrip values to identify mobility limitation in older adults

    Get PDF
    BACKGROUND/OBJECTIVE: Mobility limitation is commonly the first sign of impaired physical function and predisposes older adults to disability. Moreover, recent epidemiological studies have classified neuromuscular strength as the best explanator of mobility limitation. However, existing cutoffs have not been adequately analyzed regarding accuracy. Therefore, our aims were to define and compare the accuracy of different cutoff points of handgrip strength for the identification of mobility limitation. METHODS: Cross-sectional study with 5783 participants from the SABE (Saúde, Bem-Estar e Envelhecimento [Health, Wellbeing and Aging]) and ELSA (English Longitudinal Study of Ageing) cohorts aged 60 years or older. Handgrip strength was measured using a dynamometer. Walking speed <0.8 m/s was considered mobility limitation. Receiver operating characteristic curves and probabilities of presenting mobility limitation were calculated. RESULTS: Handgrip strength <32 kg for men and <21 kg for women demonstrated good diagnostic accuracy for mobility limitation, with 49.1% sensitivity and 79.8% specificity for men and 58.6% sensitivity and 72.9% specificity for women. The fully adjusted models had an area under the curve of 0.82 for men and 0.83 for women, with odds of presenting mobility limitation of 1.88 [95% CI: 1.50 - 2.37] for men and 1.89 [95% CI: 1.57 - 2.27] for women. CONCLUSIONS: The results of this study support the accuracy of handgrip strength as a clinical marker of mobility limitation. Furthermore, manual dynamometry is easily incorporated into clinical practice, has a good cost-benefit, besides being a simple, valid, reliable and effective method for use in both the scientific community and outpatient practice

    Association of Serum 25-Hydroxyvitamin D Deficiency with Risk of Incidence of Disability in Basic Activities of Daily Living in Adults >50 Years of Age.

    Get PDF
    BACKGROUND: Vitamin D deficiency compromises muscle function and is related to the etiology of several clinical conditions that can contribute to the development of disability. However, there are few epidemiological studies investigating the association between vitamin D deficiency and the incidence of disability. OBJECTIVES: We aimed to assess whether vitamin D deficiency is associated with the incidence of disability in basic activities of daily living (BADL) and to verify whether there are sex differences in this association. METHODS: A 4-y follow-up study was conducted involving individuals aged 50 y or older who participated in ELSA (English Longitudinal Study of Ageing). The sample consisted of 4814 participants free of disability at baseline according to the modified Katz Index. Vitamin D was assessed by serum 25-hydroxyvitamin D [25(OH)D] concentrations and the participants were classified as sufficient (>50 nmol/L), insufficient (>30 to ≤50 nmol/L), or deficient (≤30 nmol/L). Sociodemographic, behavioral, and clinical characteristics were also investigated. BADL were re-evaluated after 2 and 4 y of follow-up. The report of any difficulty to perform ≥1 BADL was considered as an incident case of disability. Poisson models stratified by sex and controlled for sociodemographic, behavioral, and clinical characteristics were carried out. RESULTS: After 4-y follow-up, deficient serum 25(OH)D was a risk factor for the incidence of BADL disability in both women (IRR: 1.53; 95% CI: 1.16, 2.03) and men (IRR: 1.44; 95% CI: 1.02, 2.02). However, insufficient serum 25(OH)D was not a risk factor for the incidence of BADL disability in either men or women. CONCLUSIONS: Independently of sex, deficient serum 25(OH)D concentrations were associated with increased risk of incidence of BADL disability in adults >50 y old and should be an additional target of clinical strategies to prevent disability in these populations

    Gender differences in the association between adverse events in childhood or adolescence and the risk of premature mortality

    Get PDF
    To examine, by gender, the relationship between adverse events in childhood or adolescence and the increased risk of early mortality (before 80 years). The study sample included 941 participants of the English Longitudinal Study of Aging who died between 2007 and 2018. Data on socioeconomic status, infectious diseases, and parental stress in childhood or adolescence were collected at baseline (2006). Logistic regression models were adjusted by socioeconomic, behavioral and clinical variables. Having lived with only one parent (OR 3.79; p = 0.01), overprotection from the father (OR 1.12; p = 0.04) and having had an infectious disease in childhood or adolescence (OR 2.05; p = 0.01) were risk factors for mortality before the age of 80 in men. In women, overprotection from the father (OR 1.22; p < 0.01) was the only risk factor for mortality before the age of 80, whereas a low occupation of the head of the family (OR 0.58; p = 0.04) and greater care from the mother in childhood or adolescence (OR 0.86; p = 0.03) were protective factors. Independently of one’s current characteristics, having worse socioeconomic status and health in childhood or adolescence increased the risk of early mortality in men. Parental overprotection increased the risk of early mortality in both sexes, whereas maternal care favored longevity in women
    corecore