Effect of Glass Fiber Hybridization on the Behavior Under Impact of Woven Carbon Fiber/Epoxy Laminates

The low-velocity impact behavior was studied in hybrid laminates manufactured by RTM with woven carbon and glass (S2) fabrics. Specimens with different thicknesses and glass fiber content (from 0 to 21 vol.%) were tested with impact energies in the range 30–245 J and the resulting deformation and fracture micromechanisms were studied using X-ray microtomography. The results of these analyses, together with those of the impact tests (maximum load and energy absorbed), were used to elucidate the role played by glass fiber hybridization on the fracture micromechanisms and on the overall laminate performance under low-velocity impact

Estimates of genetic parameters of milk yield and milk composition using random regression model in Payoya goat

Ponencia publicada en ITEA, vol.104Los resultados de 94469 registros mensuales de la producción de leche y sus componentes de 9271 cabras Payoya, paridas entre Noviembre 2002 y Diciembre de 2007 fueron analizadas mediante modelos de regresión aleatoria con el objetivo de estimar los principales parámetros genéticos para estos caracteres. Una ecuación de orden 3 para los efectos genéticos y para los efectos de ambiente individual, así como el uso de la varianza residual heterogénea fue el modelo de mejor ajuste. Para todas las variables analizadas se manifestó la tendencia al incremento en el valor de la heredabilidad (h2) a medida que se avanza en la lactación, excepto en la producción de leche en el día de control, cuyos mayores valores se presentaron a en la parte intermedia de esta. Los valores de h2 oscilaron entre 0.14 a 0.23 para la producción de leche; 0.33 a 0.40 para % de proteína; 0.10 a 0.20 para % de grasa; 0.26 a 0.40 para % de lactosa y finalmente 0.12 a 0.29 para la materia seca. En todas las variables las correlaciones genéticas fueron positivas y altas entre registros adyacentes. Se encontró una amplia variabilidad de origen genético en la forma de la curva de lactación de los animales.A total of 94469 test day records of milk yield and milk composition (fat, protein and dry matter contents) from 9271 Payoya goats, collected between November 2002 to December 2007 were analyzed using random regression models to estimate the parameter genetic for these traits. A third order equation for genetic and environment permanent effects, with a heterogeneous residual variance model was the best fit model. For all the traits analyzed results show an increase trend in the heritability values through lactation curve, except for milk yield. This shows the highest values in the middle of lactation. Heritabilities ranged from 0.14 to 0.23 for milk yield, from 0.33 to 0.40% for protein content; 0.10 to 0.20 for fat %, 0.26 to 0.40 for lactose % and finally from 0.12 to 0.29 for dry matter. Genetic correlations were positive and high between adjacent records in all traits. There was a wide genetic variability in the shape of the lactation curve

Enhanced Parallel Generation of Tree Structures for the Recognition of 3D Images

Segmentations of a digital object based on a connectivity criterion at n-xel or sub-n-xel level are useful tools in image topological analysis and recognition. Working with cell complex analogous of digital objects, an example of this kind of segmentation is that obtained from the combinatorial representation so called Homological Spanning Forest (HSF, for short) which, informally, classifies the cells of the complex as belonging to regions containing the maximal number of cells sharing the same homological (algebraic homology with coefficient in a field) information. We design here a parallel method for computing a HSF (using homology with coefficients in Z/2Z) of a 3D digital object. If this object is included in a 3D image of m1 × m2 × m3 voxels, its theoretical time complexity order is near O(log(m1 + m2 + m3)), under the assumption that a processing element is available for each voxel. A prototype implementation validating our results has been written and several synthetic, random and medical tridimensional images have been used for testing. The experiments allow us to assert that the number of iterations in which the homological information is found varies only to a small extent from the theoretical computational time.Ministerio de Economía y Competitividad MTM2016-81030-

Isotropic extensions of the vacuum solutions in general relativity

In this work, we obtain isotropic extensions of the usual spherically symmetric vacuum geometries in general relativity. Exact and perturbative solutions are derived. The classes of geometries obtained include black holes in compact and noncompact universes, wormholes in the interior region of cosmological horizons, and anti-de Sitter geometries with excess/deficit solid angle. The tools developed here are applicable in more general contexts.Comment: 12 pages, 6 figures. Version to be published in Physical Review

Frecuencias propias y índices de amortiguamiento durante la respuesta de un portico de cuatro pisos en diferentes estados de daño o reparación

Se analizan en este artículo los resultados de los ensayos sísmicos en un pórtico de hormigón armado. A través del método pseudodinámico, el pórtico fue sometido a la acción de varios acelerogramas horizontales con amplitud creciente. Dicho pórtico había sido construido siguiendo un diseño según típicas prácticas constructivas de hace 40 ó 50 años en países europeos mediterráneos. El análisis permite conocer la evolución de la frecuencia propia y el índice de amortiguamiento durante los terremotos gracias a un método de identificación que se aplica en el dominio del tiempo. Estos parámetros así obtenidos se correlacionan con el estado de la estructura y la amplitud de la deformación permitiendo obtener información útil para la predicción de la respuesta en estructuras semejantes.This paper analyses the results of the seismic tests on a reinforced-concrete frame. The frame was submitted to several increasing amplitude accelerograms by means of the pseudodynamic method. That frame had been built following typical design practices of 40 or 50 years ago in European Mediterranean countries. The analysis allows to know the evolution of the eigenfrequency and damping ratio during the earthquakes thanks to an identification method applied in the time domain. Those obtained parameters are correlated with the state of the structure and the amplitude of deformation allowing to obtain useful information for the prediction of the response of similar structures

A precise late Permian 40Ar/39Ar age for Central Iberian camptonitic lamprohyres

The Avila batholith of central Spain is composed, predominantly, of crustal-melt peraluminous granites cut by small-scale mafic alkaline bodies. Dating of the Gredos sector mafic camptonitic lamprophyre dykes was undertaken to constrain the Late Variscan tectonomagmatic evolution of the region. A well constrained late Permian, Capitanian, age of 264.5 ± 1.3 Ma was obtained by 40Ar/39Ar geochronology using amphibole separates. This new age clearly distinguishes the dykes from other episodes of alkaline mafic magmatism in the region. We suggest that the lamprophyre dykes were emplaced into already solidified granitoids after the tectonic control on magma generation changed from purely extensional to transtensional

Preliminary results of the effect of temperature and relative humidity on milk yield and components in Payoya breed goats

Un total de 81625 registros mensuales de 8380 hembras de la raza Payoya paridas en 18 ganaderías entre 2004 y 2007 fueron estudiados aplicando diferentes modelos lineales, con el objetivo de estimar los posibles efectos de un índice que combina Temperatura y Humedad Relativa (THI), sobre las variables de producción de leche y sus características físico-químicas. Los primeros resultados indicaron que existe una zona de termoneutralidad (THI entre 13 y 22) en la cual no se han evidenciado claramente los efectos del estrés térmico. Para valores de THI>22 se creó una función fT para estimar los componentes genéticos generales y los debidos al estrés térmico. Las correlaciones genéticas fueron -0.342 y -0.320 entre producción de leche y la fT indicando un antagonismo entre ambas características. Por último, se pudo poner de manifiesto la existencia de una variabilidad genética importante para capacidad de adaptación frente al estrés térmico. Estos resultados pueden brindar importantes beneficios a los criadores de la raza caprina PayoyaProduction data included 81625 test-day records of 8380 dairy goats (Payoya breed) from 18 flocks collected from 2004 to 2007. The traits analyzed were daily milk yield and milk composition, using different linear models, to determine the effect of increasing temperature-humidity index (THI) on these traits. The results report that the range between 13 and 22 for THI is the thermoneutral zone of the animals. The genetic correlations between the general additive effect and the additive effect of heat tolerance were negative (-0,342 to -0,320) to THI>22. Therefore, milk yield is antagonistic with heat tolerance. However, the genetic variability to heat tolerance could report important profits to dairy goat breeders if they consider the greater or smaller adaptability to the environmental conditions as a selection criteri

Reflexividad y Didáctica: Pensamiento que Cualifica la Acción; Acción que Cualifica al Sujeto

This paper establishes an approach which proposes that didactics in the education-learning processes favor the formal knowledge articulation which configures the academic world, with the daily life, in which the students’ life projects are registered. From this point of view, the most important “didactic resource” in the education-learning process constitutes it the subjects’ own livings. However, their potential as knowledge carriers only can emerge by the students’ reflection about them. This reflexivity such as didactic strategy can become the living in experience, which is not only a knowledge carrier, but also gives them sense, in the learners’ life project perspective. Any learning process by experience means is, in consequence, a significant learning for the student training. At the same time, reflexivity as a didactic strategy involves the teacher as a subject who evaluates his educational practices, that’s why he is also a learner.Este artículo presenta un enfoque desde el cual se propone que la didáctica de los procesos de enseñanza-aprendizaje privilegie la articulación de los contenidos académicos, es decir, el conocimiento formal, con el mundo de la vida cotidiana, en el cual se inscriben los proyectos de vida de los estudiantes. Según esta propuesta, el “recurso didáctico” más importante en el proceso de enseñanza aprendizaje lo constituyen las propias vivencias de los sujetos. Sin embargo, su potencial como portadoras de conocimiento sólo puede emerger gracias a la reflexión que el estudiante haga sobre ellas, en función de sus intereses formativos. Esta clase de reflexividad puede convertir la vivencia en experiencia, la cual no sólo es portadora de conocimiento, sino que también da sentido a éste, en la perspectiva del proyecto de vida del estudiante. Todo aprendizaje por vía de la experiencia es, en consecuencia, un aprendizaje significativo para la formación del sujeto. De igual manera, la reflexividad como estrategia didáctica, incluye al docente como sujeto que reflexiona sus prácticas de enseñanza, por lo cual, en rigor, también es un sujeto en formación

Pseudoartrosis de escafoides carpiano tratadas mediante la técnica de Matti-Russe: estudio retrospectivo de 36 casos

Presentamos un estudio retrospectivo de una serie de 36 pacientes con pseudoartrosis de escafoides operados mediante la técnica de Matti-Russe entre 1985 y 1991. Utilizamos injerto córtico esponjoso obtenido del radio (50%), cresta ilíaca (42%) y cúbito (8%) sin diferencias en la incorporación. La tasa de curación fue mayor en las pseudoartrosis medias y distales (80%) que en las de localización proximal (54%). El 80% de los fracasos de curación en la localización media y distal eran pseudoartrosis de más de 30 meses de evolución. Los cambios degenerativos en el carpo de las pseudoartrosis no curadas fueron significativamente mayores (p< 0,001) que en las que se obtuvo la consolidación. La localización y la antiguedad de la pseudoartrosis parecen ser dos importantes factores pronósticos. La técnica de Matti-Russe presenta limitaciones en la pseudoartrosis de localización proximal y en los carpos muy degenerados.We reported a retrospective study of 36 patients with a pseudoarthrosis of the carpal scaphoid bone treated by the Matti-Russe operation from 1985 to 1991. We used radial (50%), iliac (42%) or ulnar (8%) autogenous grafts without any difference in the rate of incorporation. The rate of healing of the pseudoarthrosis was higher in mid and distal location (80%) than in proximal location (54%). In 80% of cases, healing failures in the mid and distal location occurred in old pseudoarthrosis ( >3 0 months evolution). Carpal degenerative changes were significantly higher (p < 0,01) in patients with not healed pseudoarthrosis. The location and the age of the pseudoarthrosis appear to be important prognostic factors. The Matti-Russe technique has limitations when is performed either in proximal pseudoarthrosis or in the presence of advanced radiocarpal osteoarthritis

Nephroprotection by Hypoglycemic Agents: Do We Have Supporting Data?

Current therapy directed at delaying the progression of diabetic nephropathy includes intensive glycemic and optimal blood pressure control, renin angiotensin-aldosterone system blockade and multifactorial intervention. However, the renal protection provided by these therapeutic modalities is incomplete. There is a scarcity of studies analysing the nephroprotective effect of antihyperglycaemic drugs beyond their glucose lowering effect and improved glycaemic control on the prevention and progression of diabetic nephropathy. This article analyzes the exisiting data about older and newer drugs as well as the mechanisms associated with hypoglycemic drugs, apart from their well known blood glucose lowering effect, in the prevention and progression of diabetic nephropathy. Most of them have been tested in humans, but with varying degrees of success. Although experimental data about most of antihyperglycemic drugs has shown a beneficial effect in kidney parameters, there is a lack of clinical trials that clearly prove these beneficial effects. The key question, however, is whether antihyperglycemic drugs are able to improve renal end-points beyond their antihyperglycemic effect. Existing experimental data are post hoc studies from clinical trials, and supportive of the potential renal-protective role of some of them, especially in the cases of dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter 2 inhibitors. Dedicated and adequately powered renal trials with renal outcomes are neccessary to assess the nephrotection of antihyperglycaemic drugs beyond the control of hyperglycaemia