Reseñas

Juan Luis MORALES, Mis memorias. Francisco GIMÉNEZ REYNA, Memorias de un cirujano rural (Antequera y Málaga en la primera mitad del siglo XX

Locally Most Powerful Invariant Tests for Correlation and Sphericity of Gaussian Vectors

In this paper we study the existence of locally most powerful invariant tests (LMPIT) for the problem of testing the covariance structure of a set of Gaussian random vectors. The LMPIT is the optimal test for the case of close hypotheses, among those satisfying the invariances of the problem, and in practical scenarios can provide better performance than the typically used generalized likelihood ratio test (GLRT). The derivation of the LMPIT usually requires one to find the maximal invariant statistic for the detection problem and then derive its distribution under both hypotheses, which in general is a rather involved procedure. As an alternative, Wijsman's theorem provides the ratio of the maximal invariant densities without even finding an explicit expression for the maximal invariant. We first consider the problem of testing whether a set of $N$-dimensional Gaussian random vectors are uncorrelated or not, and show that the LMPIT is given by the Frobenius norm of the sample coherence matrix. Second, we study the case in which the vectors under the null hypothesis are uncorrelated and identically distributed, that is, the sphericity test for Gaussian vectors, for which we show that the LMPIT is given by the Frobenius norm of a normalized version of the sample covariance matrix. Finally, some numerical examples illustrate the performance of the proposed tests, which provide better results than their GLRT counterparts

Reconfiguración asimétrica de un manipulador paralelo de 3-gdl

In this paper an asymmetric reconfigurable parallel manipulator is presented. Asymmetric configurations are obtained by modifying the angle between each of the kinematic chains. Thanks to the reconfiguration proposal significant improvement of the manipulator performance can be obtained with respect to a Delta-type parallel robot. The computation of the best condition number is obtained, the results show that by using the redundancy, all the performance indices that depend on the Jacobian matrix can be improved as well.En este trabajo se presenta un manipulador paralelo reconfigurable asimétrico. Al modificar los ángulos de cada una de las cadenas cinemáticas pueden obtenerse configuraciones asimétricas. Gracias a la reconfiguración propuesta pueden generarse mejoras significativas del desempeño del manipulador, con respecto a un robot paralelo tipo Delta. El cálculo del mejor número de condición es obtenido, los resultados muestran que usando la redundancia todos los índices de desempeño que dependen de la matriz Jacobiana pueden ser mejorados también

Variation in dietary intake and body fatness by socioeconomic status among women in the context of Costa Rican nutrition transitions

The Nutrition Transition model posits that vegetable oils, animal source foods (ASFs) and caloric sweeteners contribute to increases in adiposity and hence body mass index (BMI). Body Mass Index is increasing more rapidly among Latin American populations of low- versus high- socioeconomic status (SES). In Latin America, few studies have evaluated dietary intake and adiposity at the individual level or how they vary by SES. The objectives of this study among Costa Rican women are to: (1) compare indicators of adiposity and dietary intake by SES and (2) evaluate the relationship between intake of foods high in vegetable oils, ASFs or caloric sweeteners and body fatness. This cross-sectional study included 128 low-, middle- and high-SES women. Anthropometry was used to assess BMI, body composition and body fat distribution. Dietary recalls (n=379) were used to assess dietary intake. Body fat percent was greater in low- versus high-SES women (31.5±3.9 vs. 28.2±4.7%). Skinfold measurements at four sites on the upper and lower body were greater in low- versus high-SES women. BMI did not vary in low- versus high-SES women. Intake frequency of foods high in vegetable oils was greater in low- and middle- (1.8 and 1.8 times/day, respectively) versus high- (1.1 times/day) SES women. For individual foods, intake frequency varied significantly by SES for high fat condiments, fried vegetables, dairy, sweetened coffee/tea and pastries and desserts. Intake frequency of Nutrition Transition food categories was not associated with percent body fat after adjustment for energy intake. Indicators of body composition provide additional information beyond BMI that are useful in understanding SES-adiposity associations in Latin America. Approaches to understanding diet and adiposity in Latin America that focus on vegetable oils, ASFs and caloric sweeteners should consider within-country variation in the pace of the Nutrition Transition, especially when explaining variation in adiposity by SES.The Wenner-Gren Foundation/[#8738]//Estados UnidosNational Institutes of Health/[T32 DK007658–27]/NIH/Estados UnidosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA

Ethylene epoxidation in microwave heated structured reactors

In the present work we show the microwave-induced heating of monolithic reactors containing a thin-layered catalyst that exhibits a strong and selective heating susceptibility under microwave irradiation. The combination of microwave radiation and structured reactors has been successfully applied for the intensification of the selective oxidation of ethylene to ethylene oxide (epoxidation) while operating at lower power consumptions and with higher energy efficiencies than in conventional heating conditions. The microwave radiation selectively heats the catalyst and the monolith walls while maintaining a relatively colder gas stream thereby creating a gas/solid temperature gradient of up to ~70 °C at a reaction temperature of 225 °C. Moreover, the influence of different parameters such as the distribution of the catalyst onto the structured monoliths or the temperature measurement techniques employed to determine the heating profiles (Optic Fibers and/or IR thermography) have been also thoroughly evaluated to justify the obtained catalytic results

Bioingeniería cutánea: aplicaciones preclínicas y clínicas

Regenerative Medicine is an emerging field that combines basic research and clinical observations in order to identify the elements required to replace damaged tissues and organs in vivo and to stimulate the body's intrinsic regenerative capacity. Great benefits are expected in this field as researchers take advantage of the potential regenerative properties of both embryonic and adult stem cells, and more recently, of induced pluripotent stem cells. Bioengineered skin emerged mainly in response to a critical need for early permanent coverage of extensive burns. Later this technology was also applied to the treatment of chronic ulcers. Our group has established a humanized mouse model of skin grafting that involves the use of bioengineered human skin in immunodeficient mice. This model is suitable for the study of physiologic and pathologic cutaneous processes and the evaluation of treatment strategies for skin diseases, including protocols for gene and cell therapy and tissue engineering.Our work has been funded by the Spanish Department of Science and Innovation (SAF2007-61019 and SAF 2010-16976), by the Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), and by the Ministry of Health (Advanced Therapies Plan, TRA 0160)