552 research outputs found

    Scaling of Information in Turbulence

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    We propose a new perspective on Turbulence using Information Theory. We compute the entropy rate of a turbulent velocity signal and we particularly focus on its dependence on the scale. We first report how the entropy rate is able to describe the distribution of information amongst scales, and how one can use it to isolate the injection, inertial and dissipative ranges, in perfect agreement with the Batchelor model and with a fBM model. In a second stage, we design a conditioning procedure in order to finely probe the asymmetries in the statistics that are responsible for the energy cascade. Our approach is very generic and can be applied to any multiscale complex system.Comment: in Europhysics Letters, 201

    A characterization of non-archimedeanly quasimetrizable spaces

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    In this paper we introduce a new structure on topological spaces which allows us to give a characterization of non-archimedeanly quasipseudometrizable spaces

    Dimension, inverse limits and GF-spaces

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    In this paper we characterize (covering) dimension in metrizable spaces in terms of fractal structures. We will also study dimension for compact metric spaces, giving a theorem relating dimension and a certain class of inverse limits, similar to that of Freudenthal

    Multiscale and Anisotropic Characterization of Images Based on Complexity: an Application to Turbulence

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    This article presents a multiscale, non-linear and directional statistical characterization of images based on the estimation of the skewness, flatness, entropy and distance from Gaussianity of the spatial increments. These increments are characterized by their magnitude and direction; they allow us to characterize the multiscale properties directionally and to explore anisotropy. To describe the evolution of the probability density function of the increments with their magnitude and direction, we use the skewness to probe the symmetry, the entropy to measure the complexity, and both the flatness and distance from Gaussianity to describe the shape. These four quantities allow us to explore the anisotropy of the linear correlations and non-linear dependencies of the field across scales. First, we validate the methodology on two-dimensional synthetic scale-invariant fields with different multiscale properties and anisotropic characteristics. Then, we apply it on two synthetic turbulent velocity fields: a perfectly isotropic and homogeneous one, and a channel flow where boundaries induce inhomogeneity and anisotropy. Our characterization unambiguously detects the anisotropy in the second case, where our quantities report scaling properties that depend on the direction of analysis. Furthermore, we show in both cases that turbulent velocity fluctuations are always isotropic, when the mean velocity profile is adequately removed

    Metodologias de análise da atividade de duas enzimas com potencial uso em biossensores

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    As enzimas superóxido dismutase (SOD) e catalase (CAT) fazem parte dos sistemas antioxidantes nos seres vivos. A alteração da atividade da CAT e SOD extraídas de organismos expostos a poluentes químicos tem sido estudada na avaliação ecotoxicológica. São apresentados os resultados preliminares referentes à implementação de metodologias para avaliar as atividades de SOD e CAT frente à possível ação de diversos poluentes de origem agrícola. As metodologias empregadas demonstraram ser satisfatórias para estudos do potencial das enzimas no desenvolvimento de biossensores. Entretanto, alguns ajustes metodológicos poderão ser realizados com relação a uma melhor adaptação às condições laboratoriais

    Medical students, spirituality and religiosity-results from the multicenter study SBRAME

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    Background: To evaluate the relationship between spirituality/religiosity (S/R) and the attitudes, beliefs and experiences of medical students in Brazil with respect to S/R in their undergraduate training and clinical practice.Methods: SBRAME (Spirituality and Brazilian Medical Education) is a multicenter study involving 12 Brazilian medical schools with 5950 medical students (MS). Participants completed a questionnaire that collected information on socio-demographic data and S/R in their undergraduate training and practice.Results: of all MS, 3630 participated in the survey (61.0%). the sample was 53.8% women and the mean age was 22.5 years. the majority of MS believed that spirituality has an impact on patients' health (71.2%) and that this impact was positive (68.2%). the majority also wanted to address S/R in their clinical practice (58.0%) and considered it relevant (75.3%), although nearly one-half (48.7%) felt unprepared to do so. Concerning their training, most MS reported that they had never participated in a spirituality and health activity (81.0%) and that their medical instructors had never or rarely addressed this issue (78.3%). the majority also believed that they should be prepared to address spiritual issues related to the health of their patients (61.6%) and that this content should be included in the medical curriculum (62.6%).Conclusion: There is a large gap between MS attitudes and expectations and the S/R training that they are receiving during their undergraduate training. the majority of MS surveyed believe that patients should have their beliefs addressed and that these beliefs could have important effects on their health and the doctor-patient relationship. These results should stimulate discussion about the place that S/R training should have in the medical curriculum.Univ Fed Juiz de Fora, Juiz de Fora, BrazilBrazilian Med Spiritist Assoc, São Paulo, BrazilUniversidade Federal de São Paulo, São Paulo, BrazilDuke Univ, Med Ctr, Durham, NC USAKing Abdulaziz Univ, Jeddah 21413, Saudi ArabiaUniversidade Federal de São Paulo, São Paulo, BrazilWeb of Scienc

    Definition and reporting of lymphadenectomy and complete mesocolic excision for radical right colectomy: a systematic review

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    Background: Several procedures have been proposed to reduce the rates of recurrence in patients with right-sided colon cancer. Different procedures for a radical right colectomy (RRC), including extended D3 lymphadenectomy, complete mesocolic excision and central vascular ligation have been associated with survival benefits by some authors, but results are inconsistent. The aim of this study was to assess the variability in definition and reporting of RRC, which might be responsible for significant differences in outcome evaluation. Methods: PRISMA-compliant systematic literature review to identify the definitions of RRC. Primary aims were to identify surgical steps and different nomenclature for RRC. Secondary aims were description of heterogeneity and overlap among different RRC techniques. Results: Ninety-nine articles satisfied inclusion criteria. Eight surgical steps were identified and recorded as specific to RRC: Central arterial ligation was described in 100% of the included studies; preservation of mesocolic integrity in 73% and dissection along the SMV plane in 67%. Other surgical steps were inconstantly reported. Six differently named techniques for RRC have been identified. There were 35 definitions for the 6 techniques and 40% of these were used to identify more than one technique. Conclusions: The only universally adopted surgical step for RRC is central arterial ligation. There is great heterogeneity and consistent overlap among definitions of all RRC techniques. This is likely to jeopardise the interpretation of the outcomes of studies on the topic. Consistent use of definitions and reporting of procedures are needed to obtain reliable conclusions in future trials. PROSPERO CRD42021241650

    Definition and reporting of lymphadenectomy and complete mesocolic excision for radical right colectomy: a systematic review

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    Background: Several procedures have been proposed to reduce the rates of recurrence in patients with right-sided colon cancer. Different procedures for a radical right colectomy (RRC), including extended D3 lymphadenectomy, complete mesocolic excision and central vascular ligation have been associated with survival benefits by some authors, but results are inconsistent. The aim of this study was to assess the variability in definition and reporting of RRC, which might be responsible for significant differences in outcome evaluation. Methods: PRISMA-compliant systematic literature review to identify the definitions of RRC. Primary aims were to identify surgical steps and different nomenclature for RRC. Secondary aims were description of heterogeneity and overlap among different RRC techniques. Results: Ninety-nine articles satisfied inclusion criteria. Eight surgical steps were identified and recorded as specific to RRC: Central arterial ligation was described in 100% of the included studies; preservation of mesocolic integrity in 73% and dissection along the SMV plane in 67%. Other surgical steps were inconstantly reported. Six differently named techniques for RRC have been identified. There were 35 definitions for the 6 techniques and 40% of these were used to identify more than one technique. Conclusions: The only universally adopted surgical step for RRC is central arterial ligation. There is great heterogeneity and consistent overlap among definitions of all RRC techniques. This is likely to jeopardise the interpretation of the outcomes of studies on the topic. Consistent use of definitions and reporting of procedures are needed to obtain reliable conclusions in future trials. PROSPERO CRD42021241650. Keywords: Colorectal cancer; Colorectal surgery; Complete mesocolic excision; D3 lymphadenectomy; Right colectomy
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