621 research outputs found
Poisson Structures on Trivial Extension Algebras
We present a class of Poisson structures on trivial extension algebras which
generalize some known structures induced by Poisson modules. We show that there
exists a one-to-one correspondence between such a class of Poisson structures
and some data involving (not necessarily flat) contravariant derivatives, and
then we give a formulation of this result in terms of Lie algebroids. Some
properties of the first Poisson cohomology are also presented. Examples coming
from Poisson modules and Poisson submanifolds are given.Comment: 31 page
The effect of material cyclic deformation properties on residual stress generation by laser shock processing
rays run on time
Significant absorption of radiation is usually accompanied by refraction.
This is not the case for rays travelling cosmic distances. We show
that the real and imaginary parts of the refraction index are indeed
commensurable, as they are related by dispersion relations, but when turning to
physical observables, the (finite) optical depth is way larger than the
(infinitesimal) time delay of the gamma rays relative to gravitational
radiation. The numerically large factor solving the apparent contradiction is
arising from basic wave properties (Bouguer-Beer-Lambert law)
and the standard cosmological model, respectively.Comment: 11 pages containing 9 plot
La utilización del vídeo para la enseñanza de conceptos básicos (calor y temperatura)
The goal of one of the inquiries implemented in the ANTEC Project (Aplicación de las Nuevas Tecnologías a la Enseñanza de las Ciencias) was to analyze the use of vídeotapes as a means to teach Sciences. In this paper we present the use of vídeotapes related to Heat and Temperature Units, in classrooms with students who were 16 years old. We expected to modify their concepts about these subjects. The results suggest the improvement of students' concepts and vocabulary, although it was not the same with the application of scientific knowledge to everyday events
Fabrication and characterization of superficially modified porous dental implants
Stress-shielding and loosening compromise the success of dental implants under real-life service conditions. This work evaluates the mechanical behavior of superficially modified porous titanium dental implants fabricated by two different routes: conventional powder metallurgy and space-holder techniques. A novel, feasible and repetitive protocol of micro-milling of the implant thread (before sintering), as well as surface modification treatments (after sintering) are also implemented. The discussion is conducted in terms of the influence of porosity and surface roughness on the stiffness and yield strength of implants. The macro-pores concentrate stress locally, and, at the same time, they could act as a barrier to the propagation of micro-cracks. Higher rugosity was observed for virgin implants obtained with spacer particles. Concerning superficially modified implants, while bioglass 1393 was the most effective coating due to its greater infiltration and adhesion capacity, chemical etching could improve osteoblast adhesion because modifies the roughness of the implant surface.Ministry of Science and Innovation of Spain PID2019-109371GB-I00Junta de Andalucía–FEDER (Spain) US-125977
Luxación traumática bilateral de cadera
Se presenta un caso de luxación bilateral simultánea de caderas, una anterior
y otra posterior, asociada a fractura del acetábulo derecho, fractura de la diáfisis
femoral derecha y una subluxación del raquis cervical.A case of simultaneous bilateral anterior and posterior dislocation of the
hip joints associated with a fracture of the right acetabulum and right femoral shaft,
and a subluxation of the cervical spine, is reported
Effect of Cutting Height on Tiller Population Density and Herbage Biomass of Buffel Grass
The aim of this trial was to investigate the effect of different cutting heights on tiller population density and herbage biomass of Buffel grass (Cenchrus ciliaris L) grown in miniature swards in a greenhouse. Four treatments with five replicates: five cm, ten cm, and 20 cm cutting height, and control (without cut) were randomly allocated. Intensity of defoliation affected the cumulative herbage harvested; the ten cm cutting height was greater (404.1 g DM m-2) than 5 cm (317.6 g DM m-2) and 20 cm (263.9 g DM m-2), respectively. Cumulative herbage harvested in the control, increased progressively until September; from then onwards tended to decrease. At the end of the trial, the highest tiller population density was found at five cm cutting height with 28 %, 48 % and 71 % more tillers than ten cm, 20 cm and control, respectively. Herbage mass at five cm and ten cm cutting height, were greater for tiller population density and herbage harvested than 20 cm and control (α\u3c 0.05)
Análisis de las estrategias bioclimáticas empleadas por Frank Lloyd Wright en la casa Jacobs I
Frank Lloyd Wright is considered one of the most influential architects of modern architecture due to the spatial and aesthetic qualities of his work. However, the importance of Wright’s construction and environmental solutions has been usually overlooked. In order to evaluate these qualities, the first house that Wright designed for the Jacobs family (Wisconsin, USA, 1937) has been analyzed. This well-known building has been much studied, and its architectural value much celebrated, but without analysing the advantages of the bioclimatic principles over interior environment. But how can the influence of this bioclimatic architecture be measured in terms of thermal comfort? Does the selected orientation improve interior comfort? And what about the natural ventilation or the deep overhangs? In order to assess this, a digital model for energy simulation has been built using Revit and Design Builder.Frank Lloyd Wright es considerado uno de los arquitectos más influyentes de la historia de la arquitectura moderna por la calidad espacial y estética de su obra. Sin embargo, la importancia de sus soluciones constructivas y medioambientales ha quedado en un segundo plano. Con el fin de destacar dichas cualidades se ha analizado la primera casa que diseñó para la familia Jacobs (Wisconsin, EE.UU., 1937), cuyo valor arquitectónico ha sido resaltado en varias ocasiones, sin que existan análisis que cuantifiquen las ventajas sobre la calidad medioambiental y el confort interior que suponen los principios bioclimáticos de su arquitectura. Pero ¿cómo medir la influencia de la arquitectura bioclimática en el confort interior? ¿Supone una mejora la orientación elegida? ¿Y la influencia de la ventilación natural y de los voladizos? Para responder a estas cuestiones se ha construido un modelo digital y se han realizado diferentes simulaciones energéticas empleando Revit y Design Builder
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