Effects of f(R) Model on the Dynamical Instability of Expansionfree Gravitational Collapse

Dark energy models based on f(R) theory have been extensively studied in literature to realize the late time acceleration. In this paper, we have chosen a viable f(R) model and discussed its effects on the dynamical instability of expansionfree fluid evolution generating a central vacuum cavity. For this purpose, contracted Bianchi identities are obtained for both the usual matter as well as dark source. The term dark source is named to the higher order curvature corrections arising from f(R) gravity. The perturbation scheme is applied and different terms belonging to Newtonian and post Newtonian regimes are identified. It is found that instability range of expansionfree fluid on external boundary as well as on internal vacuum cavity is independent of adiabatic index $\Gamma$ but depends upon the density profile, pressure anisotropy and f(R) model.Comment: 26 pages, no figure. arXiv admin note: text overlap with arXiv:1108.266

Fabricación de material de referencia 72a (aleación Cu-Al) utilizando la técnica de aleación mecánica

Los materiales de referencia empleados para la técnica de discriminación de energía de rayos X (EDE) requieren que su homogeneidad satisfaga los análisis químicos en regiones de aproximadamente 1 a 3 mm de diámetro, condición que la técnica de preparación de aleación mecánica (AM) cumple satisfactoriamente. El material de referencia 72a consiste de una aleación binaria de composición química nominal de Cu – 10 % kg/kg Al. Se preparó el material mezclando la cantidad respectiva de polvos puros de cada elemento y posteriormente se alearon en un molino de alta energía por un tiempo de 10 horas. Se tomaron muestras a diferentes tiempos con el fin de evaluar el avance de la aleación. Los resultados de medición utilizando técnicas de microsonda y gravimétricos nos indican que la composición del material es Cu 89.91 ± 0.29 % kg/kg y Al 9.81 ± 0.49 % kg/kg

Computational multiscale solvers for continuum approaches

Computational multiscale analyses are currently ubiquitous in science and technology. Different problems of interest-e.g., mechanical, fluid, thermal, or electromagnetic-involving a domain with two or more clearly distinguished spatial or temporal scales, are candidates to be solved by using this technique. Moreover, the predictable capability and potential of multiscale analysis may result in an interesting tool for the development of new concept materials, with desired macroscopic or apparent properties through the design of their microstructure, which is now even more possible with the combination of nanotechnology and additive manufacturing. Indeed, the information in terms of field variables at a finer scale is available by solving its associated localization problem. In this work, a review on the algorithmic treatment of multiscale analyses of several problems with a technological interest is presented. The paper collects both classical and modern techniques of multiscale simulation such as those based on the proper generalized decomposition (PGD) approach. Moreover, an overview of available software for the implementation of such numerical schemes is also carried out. The availability and usefulness of this technique in the design of complex microstructural systems are highlighted along the text. In this review, the fine, and hence the coarse scale, are associated with continuum variables so atomistic approaches and coarse-graining transfer techniques are out of the scope of this paper

CARACTERIZACIÓN FISICOQUÍMICA Y NIVEL DE AGRADO DE UNA MERMELADA ARTESANAL A BASE DE MANZANA (Malus pumila cv. Golden Delicious) Y CHAYOTE (Sechium edule).

Objective: to determine quality characteristics of an apple and chayote jam sweetened with three sweetener combinations and taking as a reference point, the consumer liking. Design/methodology/approximation: The first formulation consisted of: 1,050 g apple, 630 g chayote, 400 g sugar; 500 mL water were added and 10 mL lemon juice as a natural preservative. The second formulation was prepared with 1,030 g apple, 705 g chayote, 500 mL water, 600 g of commercial stevia sweetener at 0.06%, 250 mL agave honey, and 10 mL lemon juice. The third formulation was prepared with 1,040 g apple, 650 g chayote, 500 mL water, 20 g ground natural stevia leaves, 500 mL agave honey, and 10 mL lemon juice. The jams were evaluated by consumers based on a hedonic scale. Results: The physicochemical and nutritional characteristics of the most accepted jam were: total sugars 28.33%, available carbohydrates 28.45%, dietary fiber 1.46%, protein 0.18%, and ash 0.18%, among others. The most pleasant for the consumer was the apple jam with chayote sweetened with stevia and agave honey. Study limitations/ implications:  It is recommended to deepen the study of the shelf life of the product to ensure the time which it maintains its quality.Findings/conclusions. The manufacture of chayote-based jam represents a viable alternative for the diversification of chayote-based processed products.Objetivo: determinar las características de calidad de una mermelada de chayote con manzana endulzada con tres combinaciones de endulcorantes y tomando como punto de referencia, el nivel de agrado del consumidor. Diseño/metodología/aproximación: La primera formulación consistió en 1,050 g de manzana, 630 g de chayote, 400 g de azúcar, con la adición de 500 mL de agua y 10 mL de jugo de limón como conservador natural. La segunda formulación fue preparada con 1,030 g de manzana, 705 g de chayote, 500 mL de agua, 600 g de endulzante a base de estevia comercial al 0.06%, 250 mL de miel de agave y 10 mL jugo de limón. La tercera formulación fue preparada con 1,040 g de manzana, 650 g de chayote, 500 mL de agua, 20 g de estevia natural molida, 500 mL de miel de agave y 10 mL de jugo de limón. Las mermeladas fueron evaluadas por consumidores con base en una escala hedónica. Resultados: Las características fisicoquímicas y nutricionales de la mermelada más aceptada fueron: azúcares totales 28.33%, carbohidratos disponibles 28.45%, fibra dietética 1.46%, proteína 0.18%, cenizas 0.18% entre otros. La más agradable para el consumidor fue la mermelada de manzana con chayote endulzada con estevia y miel de agave. Limitaciones del estudio/implicaciones: Se recomienda profundizar en el estudio de la vida de anaquel del producto para asegurar el tiempo en que se mantiene su calidad Hallazgos/conclusiones: La fabricación de mermelada a base de chayote representa una alternativa viable para la diversificación de productos procesados a base de chayote

Intercomparación en análisis cuantitativo por espectrómetro de dispersión de energía de rayos X (EDE)

Las intercomparaciones son una base sólida para consolidar un sistema de calidad y un sustento importante en las aspiraciones para obtener la certificación de un laboratorio. Con éstas, el desempeño analítico de cada laboratorio tiene una evaluación objetiva al comparar sus valores con los mejores resultados de otros laboratorios, asegurando siempre la confidencialidad de los participantes [1]. El Centro Nacional de Metrología (CENAM) organizó el primer ejercicio de intercomparación de microanálisis por espectrometría de discriminación de energía de rayos X (EDE). Se realizó una invitación pública a los laboratorios que desearan participar en la prueba 610-IL-0998, logrando la participación de 7 laboratorios. Los resultados indican que los laboratorios que utilizaron materiales de referencia y accesorios que permiten tener mayor control sobre el proceso de medición obtienen resultados con menor sesg

Sobre la bionomía de los Celíferos (Orthoptera, Caelifera) de Cantabria (N. España)

En: Actas de la 5.ª Reunión Internacional de la Sociedad de Ortopterólogos. 17-20 julio, 1989 Valsaín (Segovia), EspañaSe presenta un estudio bianómico sobre cl muestreo de Ortópteros Celíferos realizado en la Comunidad Autónoma de Cantabria desde el año 1985 hasta el actual. La Comunidad de Cantabria. situada en el norte de la Península Ibérica. tiene una extensión aproximada de 5.300 km' y una gradación altitudinal desde O hasta los 2.600 m. Presenta igualmente grandes variaciones climáticas con la consiguiente diversidad botánica. El citado muestreo se efectuó en un total de 119 localidades. de las que se han obtenido 162 muestras con las que se ha procurado recolectar ejemplares en todas las cuadrículas con coordenadas U.T.M. de 10 km de lado. así como todos los biotopos existentes. Esta prospección ha proporcionado un total de 6.496 ejemplares de Ortópteros Celiferos pertenecientes a 41 especies de 20 géneros agrupados en 3 familias (Tetrigidae. Catantopidae y Acrididae). de las cuales 12 especies y dos subespecies constituyen nuevas citas para Cantabria. Se describen las comunidades vegetales muestreadas y se relacionan las especies de Celíferos encontradas

An unsupervised data completion method for physically-based data-driven models

Data-driven methods are an innovative model-free approach for engineering and sciences, still in process of maturation. The idea behind is the combination of data analytics techniques, to handle the huge amount of data derived from continuous monitoring or experimental measurements, and of the constraints imposed by universal physical laws, particular to the field in hands. A well-known problem in the former corresponds to the quality and completeness of the available data that, sometimes, are so poor that make the predictions useless. In data-driven simulation-based engineering and sciences (DDSBES), the intrinsic physical constraints may help in completing the missing data in a more precise manner, by forcing them to remain in the manifold defined by the physical laws. In this work, a suitable imputation method to complete incomplete data that preserves the data context-dependent structure is presented. This is accomplished by enforcing the data to fulfill the set of physical constraints, specific to the problem. For this purpose, a generalization of the weighted mean concept is proposed, where the distance to the admissible points (in a physical sense) is used as a weighting function to get the optimal candidate. The method is evaluated in a classical regression problem, where it is compared with other standard methods, showing better results. Then, its application is illustrated in two data-driven problems, where no filling data procedure has been yet proposed, showing good predictive capability, provided that the data are close enough to the actual system state

1D charge density wave in the hidden order state of URu2Si2

Moir\'e patterns can lead to fundamentally new electronic behavior when formed between two atomic lattices slightly shifted with respect to each other. A solid is however not just characterized by the atomic lattice, but also by charge or magnetic excitations that do not need to be commensurate to the lattice. This raises the question if one can obtain a moir\'e by combining periodic electronic modulations and the atomic lattice. Here we report on the discovery of a one-dimensional charge density wave (1D-CDW) which is a moir\'e pattern between the atomic lattice and a hot spot for electronic scattering in the bandstructure of the hidden order (HO) state of URu$_2$Si$_2$. The moir\'e is produced by fracturing the crystal at low temperatures. Our results suggest that charge interactions are among the most relevant features competing with HO in URu$_2$Si$_2$

Persuading older adults’ to social and physical activities

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