A Study of Soil Microstructure Using Bender Element Tests

An application of bender elements to measure the effect of soil microstructure in shear wave velocity is presented. A testing program was carried out on Mexico City sediments using a triaxial cell fitted with bender elements. Shear wave velocities were measured during isotropic consolidation and during failure. From the results of these tests simple expressions were obtained which describe the variations of shear wave velocity with the current state in terms of the effective stress and axial deformation

Energetics and the magnetic state of Mn2 adsorbed on Au(111): Dimer bond distance dependence

"In this work we present a theoretical study of the adsorption Mn2 dimer on the Au(111) surface. Here we use the density functional theory to construct a map of adsorption energies, EA, of Mn2 on a Au(111) surface as a function of interatomic bond distance, , among Mn atoms. We employed a 4×4 supercell of Au(111) surface which lead us to reach values in the range from 2.6 to 6.8 Å. To make a full study of the adsorption energies we considered the antiferromagnetic (AFM) and ferromagnetic (FM) states of the Mn2 on the surface. The energy landscape contains local minima when the Mn atoms are adsorbed above triangular sites and barriers that the Mn adatoms have to overcome when they move across the Au(111) surface along various paths. Our results show that the lowest energy state corresponds to the state in which the Mn atoms are next-nearest neighbors and are antiferromagnetically coupled. Furthermore, all the local minima with higher bonding energy are also those in the antiferromagnetic state. Nevertheless we find a short interval in which the FM state has lower energy than the AFM one. Finally, scanning tunneling microscope simulations for various dimer configurations on surface are reported.

Long-term consequences of alcohol use in early adolescent mice: Focus on neuroadaptations in GR, CRF and BDNF.

Our aim was to assess the cognitive and emotional state, as well as related-changes in the glucocorticoid receptor (GR), the corticotropin-releasing factor (CRF) and the brain-derived neurotrophic factor (BDNF) expression of adolescent C57BL/6J male mice after a 5-week two-bottle choice protocol (postnatal day [pd]21 to pd52). Additionally, we wanted to analyse whether the behavioural and neurobiological effects observed in late adolescence (pd62) lasted until adulthood (pd84). Behavioural testing revealed that alcohol during early adolescence increased anxiety-like and compulsive-related behaviours, which was maintained in adulthood. Concerning cognition, working memory was only altered in late adolescent mice, whereas object location test performance was impaired in both ages. In contrast, novel object recognition remained unaltered. Immunohistochemical analysis showed that alcohol during adolescence diminished BDNF+ cells in the cingulate cortex, the hippocampal CA1 layer and the central amygdala. Regarding hypothalamic-pituitary-adrenal axis (HPA) functioning, alcohol abuse increased the GR and CRF expression in the hypothalamic paraventricular nucleus and the central amygdala. Besides this, GR density was also higher in the prelimbic cortex and the basolateral amygdala, regardless of the animals' age. Our findings suggest that adolescent alcohol exposure led to long-term behavioural alterations, along with changes in BDNF, GR and CRF expression in limbic brain areas involved in stress response, emotional regulation and cognition.post-print4591 K

IAA : Información y actualidad astronómica (10)

Sumario : Investigación: Chorros relativistas en núcleos activos de galaxias.-- Materia oscura: a tientas por el Universo.-- Ventana Abierta: Físico teórico autónomo se ofrece para.-- Charlas con… Robert Haberle.-- Actualidad Científica: La búsqueda de las estrellas más viejas de la Galaxia.-- Un superbólido más brillante que la Luna llena surcó el cielo argelino.-- Actividades IAA.-- Agenda.Esta revista se publica con la ayuda de la Acción Especial DIF 2001-4284-E del Programa Nacional de Difusión de la Ciencia y la Tecnología, del Ministerio de Ciencia y TecnologíaN

Study of the Microstructure Evolution of Low-pH Cements Based on Ordinary Portland Cement (OPC) by Mid- and Near-Infrared Spectroscopy, and Their Influence on Corrosion of Steel Reinforcement

Low-pH cements are designed to be used in underground repositories for high level waste. When they are based on Ordinary Portland Cements (OPC), high mineral admixture contents must be used which significantly modify their microstructure properties and performance. This paper evaluates the microstructure evolution of low-pH cement pastes based on OPC plus silica fume and/or fly ashes, using Mid-Infrared and Near-Infrared spectroscopy to detect cement pastes mainly composed of high polymerized C-A-S-H gels with low C/S ratios. In addition, the lower pore solution pH of these special cementitious materials have been monitored with embedded metallic sensors. Besides, as the use of reinforced concrete can be required in underground repositories, the influence of low-pH cementitious materials on steel reinforcement corrosion was analysed. Due to their lower pore solution pH and their different pore solution chemical composition a clear influence on steel reinforcement corrosion was detecte

Analysis of the Influence of Terrain Orientation on the Design of PV Facilities with Single-Axis Trackers

This paper investigates how to optimally orient the photovoltaic solar trackers of an axis parallel to the terrain, applying the sky model of Hay–Davies. This problem has been widely studied. However, the number of studies that consider the orientation (inclination and azimuth of the terrain) is very limited. This paper provides an examination of incident solar irradiance that can be extended to terrain with variable orientation and in consideration of different azimuths of the axis of rotation. Furthermore, a case study of the south of Spain is provided, considering different inclination and orientation terrain values. The results obtained in this study indicate, as a novelty, that for lands that are not south facing, the rotation axis azimuth of solar trackers should be different from zero and adjusted to the same direction as the land azimuth in order to maximize energy production. Annual energy production is sensitive to changes in the rotation axis azimuths of solar trackers (an influence of around 3% of annual energy production)

2-DE analysis of sera protein expression profiles in early stages of human neonatal development. A preliminary study.

Comunicaciones a congreso

Estudio comparativo de dos programas de entrenamiento de la memoria en personas mayores con quejas subjetivas de memoria: un análisis preliminar.

Introducción: A pesar del declive cognitivo que se produce con la edad, numerosos estudios han demostrado la eficacia que tienen los programas de entrenamiento de la memoria para mejorar diversas áreas neurocognitivas en las personas mayores. Objetivo: analizar de forma preliminar el efecto diferencial de dos programas de entrenamiento de la memoria en personas mayores sobre diversas funciones cognitivas. Método: 18 sujetos entre 61 y 81 años han participado, o bien en un programa de entrenamiento en estrategias de memoria, o bien en un programa de entrenamiento en olvidos cotidianos. En todos ellos se evaluó la percepción subjetiva de la memoria, así como el desempeño cognitivo antes y después del entrenamiento. Resultados: se encontró una mejoría estadísticamente significativa en el cuestionario de quejas subjetivas de memoria en ambos grupos, y sólo se encontró cierta mejoría en memoria de trabajo visoespacial (test Corsi inverso) y en razonamiento (Analogías) en el grupo que recibió un entrenamiento en olvidos cotidianos. Conclusiones: los programas de entrenamiento de la memoria mejoran la percepción subjetiva que tienen las personas mayores del funcionamiento de la memoria, y ello es independiente de la metodología de entrenamiento utilizada

An Experimental Set-Up for Measurement of the Power Absorbed from 900 MHz GSM Standing Waves by Small Animals, Illustrated by Application to Picrotoxin-Treated Rats

[Abstract] We describe an experimental set-up for exposure of small animals to radiofrequency standing waves that allows direct measurement of the power absorbed by the animal. Essentially, the set-up consists of a metallic box containing an antenna and experimental animal immobilized in a methacrylate holder; a signal generator feeding the antenna; and a power meter. In addition, the box can also contain a video camera to record the animal's behaviour, and a receiving antenna (connected externally to a power meter and a spectrum analyser) to detect alien radiation and harmonics. The absorbed power measurement trivially allows calculation of whole-body mean SAR from the animal's weight; and assuming local SARs to be proportional to whole-body mean SAR, the latter can be used to adjust organ-specific SAR predictions obtained by simulation using a commercial FDTD program with a numerical phantom. The use of the system is illustrated by application to rats given subconvulsive doses of picrotoxin to induce a seizure-prone state analogous to epilepsy: levels of the neuronal activity marker c-Fos in the frontal and piriform cortex of picrotoxin-treated rats exposed to 900 MHz GSM radiation were twice as high as those of unexposed animals

IAA : Información y actualidad astronómica (4)

Sumario : Investigación : Galaxias huéspedes de cuásares.-- El gigante gaseoso y su gran mancha roja.-- Ventana Abierta: Un futuro incierto.-- Charlas con… John Hutchings.-- Actualidad Científica: La edad de la galaxia.-- Sorpresas en el cinturón de Kuiper.-- Actividades IAA.-- Agenda.N