Alternating direction implicit time integrations for finite difference acoustic wave propagation: Parallelization and convergence

This work studies the parallelization and empirical convergence of two finite difference acoustic wave propagation methods on 2-D rectangular grids, that use the same alternating direction implicit (ADI) time integration. This ADI integration is based on a second-order implicit Crank-Nicolson temporal discretization that is factored out by a Peaceman-Rachford decomposition of the time and space equation terms. In space, these methods highly diverge and apply different fourth-order accurate differentiation techniques. The first method uses compact finite differences (CFD) on nodal meshes that requires solving tridiagonal linear systems along each grid line, while the second one employs staggered-grid mimetic finite differences (MFD). For each method, we implement three parallel versions: (i) a multithreaded code in Octave, (ii) a C++ code that exploits OpenMP loop parallelization, and (iii) a CUDA kernel for a NVIDIA GTX 960 Maxwell card. In these implementations, the main source of parallelism is the simultaneous ADI updating of each wave field matrix, either column-wise or row-wise, according to the differentiation direction. In our numerical applications, the highest performances are displayed by the CFD and MFD CUDA codes that achieve speedups of 7.21x and 15.81x, respectively, relative to their C++ sequential counterparts with optimal compilation flags. Our test cases also allow to assess the numerical convergence and accuracy of both methods. In a problem with exact harmonic solution, both methods exhibit convergence rates close to 4 and the MDF accuracy is practically higher. Alternatively, both convergences decay to second order on smooth problems with severe gradients at boundaries, and the MDF rates degrade in highly-resolved grids leading to larger inaccuracies. This transition of empirical convergences agrees with the nominal truncation errors in space and time.Comment: 20 pages, 5 figure

Improving randomness characterization through Bayesian model selection

Nowadays random number generation plays an essential role in technology with important applications in areas ranging from cryptography, which lies at the core of current communication protocols, to Monte Carlo methods, and other probabilistic algorithms. In this context, a crucial scientific endeavour is to develop effective methods that allow the characterization of random number generators. However, commonly employed methods either lack formality (e.g. the NIST test suite), or are inapplicable in principle (e.g. the characterization derived from the Algorithmic Theory of Information (ATI)). In this letter we present a novel method based on Bayesian model selection, which is both rigorous and effective, for characterizing randomness in a bit sequence. We derive analytic expressions for a model's likelihood which is then used to compute its posterior probability distribution. Our method proves to be more rigorous than NIST's suite and the Borel-Normality criterion and its implementation is straightforward. We have applied our method to an experimental device based on the process of spontaneous parametric downconversion, implemented in our laboratory, to confirm that it behaves as a genuine quantum random number generator (QRNG). As our approach relies on Bayesian inference, which entails model generalizability, our scheme transcends individual sequence analysis, leading to a characterization of the source of the random sequences itself.Comment: 25 page

Specialized Pro-Resolving Lipid Mediators: The Future of Chronic Pain Therapy?

Chronic pain (CP) is a severe clinical entity with devastating physical and emotional consequences for patients, which can occur in a myriad of diseases. Often, conventional treatment approaches appear to be insufficient for its management. Moreover, considering the adverse effects of traditional analgesic treatments, specialized pro-resolving lipid mediators (SPMs) have emerged as a promising alternative for CP. These include various bioactive molecules such as resolvins, maresins, and protectins, derived from ω-3 polyunsaturated fatty acids (PUFAs); and lipoxins, produced from ω-6 PUFAs. Indeed, SPMs have been demonstrated to play a central role in the regulation and resolution of the inflammation associated with CP. Furthermore, these molecules can modulate neuroinflammation and thus inhibit central and peripheral sensitizations, as well as long-term potentiation, via immunomodulation and regulation of nociceptor activity and neuronal pathways. In this context, preclinical and clinical studies have evidenced that the use of SPMs is beneficial in CP-related disorders, including rheumatic diseases, migraine, neuropathies, and others. This review integrates current preclinical and clinical knowledge on the role of SPMs as a potential therapeutic tool for the management of patients with CP

Estudio bioedafologico preliminar de la isla gorgona

Los suelos de la Isla Oorgona son Inceptisoles con buena a baja saturación de bases (Eutropepts y Dystropepts respectivamente). con tendencia a ser ácidos y buena capacidad de intercambio catíóníco, Domina en ellos la textura arcillosa; el contenido de materia orgánica es alto en los horizontesO y A. razón por la cual predominan. en la fauna edáfica las formas de hábitos fltófagos y saprófagos. Los más  epresentativos de la fauna interna del suelo (O a 40 cm) son Insecta y Annelida e Insecta y Aracnida en la fauna superficial

Higth performance liquid chromatography technique design and validation for quantification of tolbutamide, acetamide and propianamide in solid dispersions

El estudio del tipo de interacción involucrada en la formación de dispersiones sólidas de tolbutamida con distintas proporciones de acetamida y propianamida, ha requerido del diseño y validación de un método analítico por cromatografía líquida de alta eficacia (CLAE) que permita cuantificar la proporción de los transportadores en mezclas físicas y en dispersión sólida. El método resultó ser lineal, preciso y exacto en el intervalo de concentración de 100-1,56 μg/mL para tolbutamida y 50-0,781 μg/mL para acetamida y propianamida.The interest to design and validate a high performance liquid chromatography method for quantification of tolbutamide, acetamide and propianamide in solid dispersions, was to find a relation among the amount of carriers and the active substance in solid dispersions, in order to further investigate the drug-carrier interaction pattern responsible of solid dispersion formation. The method was lineal, precise and accurate in the concentration range between 100.0 - 1.56 μg/ mL for tolbutamide and 50.0 - 0.78 μg/mL for acetamide and propianamide

A novel East African monopartite begomovirus-betasatellite complex that infects Vernonia amygdalina

The complete genomes of a monopartite begomovirus (genus Begomovirus, family Geminiviridae) and an associated betasatellite found infecting Vernonia amygdalina Delile (family Compositae) in Uganda were cloned and sequenced. Begomoviruses isolated from two samples showed the highest nucleotide sequence identity (73.1% and 73.2%) to an isolate of the monopartite begomovirus tomato leaf curl Vietnam virus, and betasatellites from the same samples exhibited the highest nucleotide sequence identity (67.1% and 68.2%) to vernonia yellow vein Fujian betasatellite. Following the current taxonomic criteria for begomovirus species demarcation, the isolates sequenced here represent a novel begomovirus species. Based on symptoms observed in the field, we propose the name vernonia crinkle virus (VeCrV) for this novel begomovirus and vernonia crinkle betasatellite (VeCrB) for the associated betasatellite. This is the first report of a monopartite begomovirus-betasatellite complex from Uganda

Aplicación de la metodología diagnostica riesgo-vivienda-salud para el cálculo del riesgo de la vivienda urbana en Paraguay, Cuba y Argentina

En este artículo se explica el desarrollo de una metodología Diagnostica de Estimación del Riesgo de la Vivienda Urbana para la Salud (DRVS), desde una perspectiva holística del Riesgo. También se describe el modelo computacional asociado (RVS) que implementa esta metodología y se describen los resultados de su aplicación en 3 países de Latinoamérica Paraguay, Cuba y Argentina, que fueron elegidos por ser partes de la red de vivienda saludable de la Organización Panamericana de la Salud. El dominio del problema del riesgo de la vivienda urbana se supone complejo y no lineal, y ha sido modelado empleando redes neuronales artificiales que emula una red conceptual de relación de factores sociales, económicos y demográficos que no se ajusta a los modelos clásicos. El cálculo de un índice de riesgo permitiría a las autoridades de salud dirigir más acertadamente los fondos disponibles, en base a una comparación objetiva entre diferentes asentamientos poblacionales. Se exponen los resultados del trabajo de campo, analizando los factores constituyentes y el índice de riesgo final obtenido en los distintos países donde se aplicó la DRVS.Sociedad Argentina de Informática e Investigación Operativ

Estudio bioedafológico preliminar de la isla gorgona

Los suelos de la Isla Gorgona son Inceptisoles con buena a baja saturación de bases (Eutropepts y Dystropepts respectivamente), con tendencia a ser ácidos y buena capacidad de intercambio catiónico. Domina en ellos la textura arcillosa: el contenido de materia orgánica es alto en los horizontes O y A, razón por la cual predominan, en la fauna edáfica las formas de hábitos fitófagos y saprófagos. Los más representativos de la fauna internadel suelo (0 a 40 ern) son Insecta y Annelida e Insecta y Aracnida en la faunasuperficial