864 research outputs found

    Nonextensivity and Galaxy Clustering in the Universe

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    We investigate two important questions about the use of the nonextensive thermostatistics (NETS) formalism in the context of nonlinear galaxy clustering in the Universe. Firstly, we define a quantitative criterion for justifying nonextensivity at different physical scales. Then, we discuss the physics behind the ansatz of the entropic parameter q(r)q(r). Our results suggest the approximate range where nonextensivity can be justified and, hence, give some support to the applicability of NETS to the study of large scale structures.Comment: 8 pages, written version of a talk presented in the International Workshop on Trends and Perspectives on Extensive and Non-Extensive Statistical Mechanics. Accepted for publication in Physica

    An automatic methodology for estimating eddy diffusivities from experimental data

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    A technique for estimating eddy diffusivities in a turbulent atmospheric layer is presented; the scheme adopted is based on an inverse-problem methodology. The inverse problem is formulated as a nonlinear constrained optimization problem, where the objective function is defined through the square differences between experimental and model data. The direct mathematical model is given by the advection-diffusion equation, which is solved by second-order finite-difference method. In the presence of noise it is necessary to use some regularization term; the Tikhonov function and an entropic regularization of zeroth, first and second orders are used in this paper. In addition, two inversion strategies are used: alternate and simultaneous eddy diffusivities estimation. Numerical experiments show a good performance of the proposed methodology

    Micofagia bacteriana.

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    Experimental and theoretical investigations on a CVD grown thin film of polymeric carbon nitride and its structure

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    A polymeric carbon nitride thin film has been grown using chemical vapor deposition. The characterization of the material shows that it has the same molecular composition as a formerly synthesized graphitic carbon nitride powder but both substances differ widely in their structural organization. In particular, our analyses reveal a paradoxical character in which the thin film sample exhibits simultaneously a high degree of organization in the stacking of the polymer sheets with strong inter-layer interactions, as expected from the growth technique, and a complete lack of crystallinity. A comprehensive theoretical study based on massive semi-empirical quantum chemistry computations has permitted to explain the properties of the material and to elucidate fundamental issues regarding the structural conformation of graphitic carbon nitride

    The effects of a high-protein, high-calorie, fiber- and fructo-oligosaccharide-enriched enteral formula on nutritional status, bowel habits and tolerance: Safety and effectiveness of enteral nutrition in elderly spanish patients (Sens study)

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    Background: Enteral nutrition (EN) is an effective nutritional intervention for patients at risk of malnutrition or malnourished. However, complications such as gastrointestinal intolerance, hyperglycemia or refeeding syndrome can be triggered by EN. Aim: To investigate the effects of a tube feeding formula (TFF) on patients’ nutritional status, biochemical status, bowel habits and safety. Methodology: Observational, prospective and multicenter study. Patients = 18 years, undernourished or at nutritional risk, who were prescribed a high-calorie, high-protein, fiber-fortified TFF were included. Patients were evaluated over a period of eight weeks (baseline [V1], four weeks [V2] and eight weeks [V3]). Results: A statistically significant increase in weight (1.5 kg), body mass index (0.6 kg/m2) and nutritional intake (59.7 kcal/day) was observed between V1 and V2. Between V1 and V3, there was a statistically significant decrease in the percentage of individuals with abnormal biochemical markers for glucose, potassium, total protein and albumin. The number of patients’ bowel movements remained stable throughout the study with a mean of 1.1 daily bowel movements. Conclusion: The TFF was safe and well tolerated, improving patients’ nutritional status without altering patients’ bowel habits. Introducción: la nutrición enteral es una intervención efectiva para pacientes desnutridos o en riesgo de sufrir desnutrición. Sin embargo, puede desencadenar complicaciones como intolerancia gastrointestinal, hiperglicemia o síndrome de realimentación. Objetivo: investigar los efectos de una fórmula de nutrición enteral por sonda en el estado nutricional y bioquímico, hábitos gastrointestinales y seguridad de los pacientes. Metodología: estudio observacional, prospectivo y multicéntrico. Se incluyeron pacientes = 18 años, desnutridos o en riesgo de desnutrición, tributarios de recibir una fórmula de nutrición enteral hipercalórica, hiperproteica, y rica en fibra y fructooligosacáridos. Los pacientes fueron evaluados durante 8 semanas en 3 visitas (V1, inicial; V2, 4 semanas; V3, 8 semanas). Resultados: entre V1 y V2 se observó un incremento estadísticamente significativo en peso (1, 5 kg), índice de masa corporal (0, 6 kg/m2) e ingesta calórica (59, 7 kcal/día). Entre V1 y V3, existió un descenso en el porcentaje de pacientes con valores anormales de glucosa, potasio, proteína total y albúmina. Los hábitos intestinales se mantuvieron estables durante el estudio (1, 1 deposiciones diarias de media). Conclusión: la fórmula fue segura, tolerada, y mejoró el estado nutricional del paciente sin alterar los hábitos intestinales

    Photocatalytic activity of a new composite material of Fe (III) oxide nanoparticles wrapped by a matrix of polymeric carbon nitride and amorphous carbon

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    Polymeric carbon nitride was synthesized from urea and doped with Cu and Fe to act as co-catalysts. The material doped with Fe was a new composite material composed of Fe(III) oxides (acting as a co-catalyst) wrapped by the polymer layers and amorphous carbon. Furthermore, the copper doped material was described in a previous report. The photocatalytic degradation of the azo dye direct blue 1 (DB) was studied using as photocatalysts: pure carbon nitride (CN), carbon nitride doped with Cu (CN-Cu) and carbon nitride doped with Fe (CN-Fe). The catalysts were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), by X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller method (BET), etc. The adsorption phenomenon was studied using the Langmuir and Freundlich models. For the kinetic study, a solution of 500 mg L-1 of DB1 was treated with each catalyst, visible light and H2O2. The dye concentration was measured by spectrophotometry at the wavelength of 565 nm, and the removal of the total organic content (TOC) was quantified. BET analysis yielded surface areas of 60.029, 20.116 and 70.662 m2g-1 for CN, CN-Cu and CN-Fe, respectively. The kinetics of degradation were pseudo-first order, whose constants were 0.093, 0.039 and 0.110 min-1 for CN, CN-Cu and CN-Fe, respectively. The total organic carbon (TOC) removal reached the highest value of 14.46% with CN-Fe

    Successful Treatment of Recalcitrant Pediatric Pemphigus Vulgaris With Rituximab

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    Pemphigus vulgaris (PV) affecting the pediatric population is extremely rare, representing less than 3% of all PV cases. Conventional treatment with systemic steroids with or without adjuvant immunosuppressants used in adult cases of PV is often employed. However, pediatric cases often present a therapeutic challenge given their increased susceptibility to systemic therapy’s associated risks. To date, no specific guidelines regarding treatment strategies in this patient population exist. We describe a 14-year-old Hispanic female patient with severe, recalcitrant PV with suboptimal treatment response to systemic steroids and intravenous immunoglobulin (IVIG) successfully treated with rituximab (RTX), showing control of disease in as early as 2 weeks after treatment initiation. To our knowledge, only 45 cases of pediatric PV successfully treated with RTX have been reported in the literature, highlighting its use as a safe therapeutic option in this patient population

    Future environmental and agricultural impacts of Brazil's Forest Code

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    The role of improving the enforcement of Brazil's Forest Code in reducing deforestation in the Amazon has been highlighted in many studies. However, in a context of strong political pressure for loosening environmental protections, the future impacts of a nationwide implementation of the Forest Code on both environment and agriculture remain poorly understood. Here, we present a spatially explicit assessment of Brazil's 2012 Forest Code through the year 2050; specifically, we use a partial equilibrium economic model that provides a globally consistent national modeling framework with detailed representation of the agricultural sector and spatially explicit land-use change. We test for the combined or isolated impacts of the different measures of the Forest Code, including deforestation control and obligatory forest restoration with or without environmental reserve quotas. Our results show that, if rigorously enforced, the Forest Code could prevent a net loss of 53.4 million hectares (Mha) of forest and native vegetation by 2050, 43.1 Mha (81%) of which are in the Amazon alone. The control of illegal deforestation promotes the largest environmental benefits, but the obligatory restoration of illegally deforested areas creates 12.9 Mha of new forested area. Environmental reserve quotas further protect 5.8 Mha of undisturbed natural vegetation. Compared to a scenario without the Forest Code, by 2050, cropland area is only reduced by 4% and the cattle herd by 8%. Our results show that compliance with the Forest Code requires an increase in cattle productivity of 56% over four decades, with a combination of a higher use of supplements and an adoption of semi-intensive pasture management. We estimate that the enforcement of the Forest Code could contribute up to 1.03 PgCO<sub>2</sub>e to the ambitious GHG emissions reduction target set by Brazil for 2030

    Dynamical model and nonextensive statistical mechanics of a market index on large time windows

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    The shape and tails of partial distribution functions (PDF) for a financial signal, i.e. the S&P500 and the turbulent nature of the markets are linked through a model encompassing Tsallis nonextensive statistics and leading to evolution equations of the Langevin and Fokker-Planck type. A model originally proposed to describe the intermittent behavior of turbulent flows describes the behavior of normalized log-returns for such a financial market index, for small and large time windows, both for small and large log-returns. These turbulent market volatility (of normalized log-returns) distributions can be sufficiently well fitted with a χ2\chi^2-distribution. The transition between the small time scale model of nonextensive, intermittent process and the large scale Gaussian extensive homogeneous fluctuation picture is found to be at ca.ca. a 200 day time lag. The intermittency exponent (κ\kappa) in the framework of the Kolmogorov log-normal model is found to be related to the scaling exponent of the PDF moments, -thereby giving weight to the model. The large value of κ\kappa points to a large number of cascades in the turbulent process. The first Kramers-Moyal coefficient in the Fokker-Planck equation is almost equal to zero, indicating ''no restoring force''. A comparison is made between normalized log-returns and mere price increments.Comment: 40 pages, 14 figures; accepted for publication in Phys Rev
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