Estrelles binàries de raigs-X amb emissió ràdio

Les binaries o estrelles dobles fisiques son sistemes formats per dues estrelles lligades gravitatoriament. Avui en dia sabem que aquest és un fenomen molt comú a la galaxia, on aproximadament la meitat de les estrelles s'han format i han donat lloc a aquesta mena de sistemes...

Photometric and Halpha observations of LSI+61·303: detection of a 26 day V and JHK band modulation

We present new optical and infrared photometric observations and high resolution H α spectra of the periodic radio star LSI+61◦303. The optical photometric data set covers the time interval 1985-1993 and amounts to about a hundred nights. A period of ∼26 days is found in the V band. The infrared data also present evidence for a similar periodicity, but with higher amplitude of variation ((0.m 2). The spectroscopic observations include 16 intermediate and high dispersion spectra of LSI+61◦303 collected between January 1989 and February 1993. The H α emission line profile and its variations are analyzed. Several emission line parameters -- among them the H α EW and the width of the H α red hump -- change strongly at or close to radio maximum, and may exhibit periodic variability. We also observe a significant change in the peak separation. The H α profile of LSI+61◦303 does not seem peculiar for a Be star. However, several of the observed variations of the H α profile can probably be associated with the presence of the compact, secondary star.

Evidence of Halpha periodicities in LSI+61·303

We present the results of analyzing H$\alpha$ spectra of the radio emitting X-ray binary LS I+61303. For the first time, the same 26.5 d radio period is clearly detected in the H$\alpha$ emission line. Moreover, the equivalent width and the peak separation of the H$\alpha$ emission line seem also to vary over a time scale of 1600 days. This points towards the $\sim4$ yr modulation, detected in the radio outburst amplitude, being probably a result of variations in the mass loss rate of the Be star and/or density variability in the circumstellar disk. In addition, the dependence of the peak separation from the equivalent width informs us that the LS I+61303 circumstellar disk is among the densest of Be-stars.

V-band observations of V4641 Sagittarii

In this note we report high time resolution V Johnson photometry of the microquasar V4641 Sgr (SAX J1819.3-2525 - XTE J1819-254). This source was discovered as an X-ray transient by BeppoSAX and RossiXTE satellites (In't Zand et al. 1999; Markwardt et al. 1999). On 1999 September, a very fast transient optical and X-ray outburst was observed, reaching up to ...

Utilización de software de corrección automática en el campo de las ciencias de la salud

We live in an era of profound changes in university education. The implementation of Bologna plan has led us to raise new teaching methodologies, to review the role of the student, competency assessment, the incorporation of ICT. Unthinkable acts, one or two decade ago. The TIC concept is very broad and is attributed to the media, processes and content usage. Inside the supports and platforms, we stress tools that allow automatic correction of exercises, because they are instruments of great educational value because instantly they assess students and provide instant feedback about the knowledge that they have either as message support or note. If the power of these tools, we add the Internet, using e-learning environment, the results allow us to work, edit, evaluate, resolve doubts, and so on, anywhere, anytime. We present part of a platform and the results of its use in the field of health sciences

Desarrollo de una aplicación interactiva multimedia: Elaboración industrial de una emulsión de fase externa silicónica

A partir de una primera experiencia en el desarrollo de una aplicación interactiva multimedia, como fue la elaboración de comprimidos infantiles de paracetamol y aplicación de las Normas de Correcta Fabricación , y visto que ha tenido una gran aceptación por parte de los alumnos, se decidió el realizar una nueva aplicación interactiva multimedia que considerara la otra práctica que se realizaba en la planta piloto del SDM (Servei de Desenvolupament del Medicament), la cual consiste en la elaboración de una emulsión silicónica. Ambas prácticas se llevan a cabo presencialmente en la asignatura de Tecnología Farmacéutica II. En esta segunda aplicación multimedia, si bien se ha mantenido una estructura similar a la primera editada, se ha intentado mejorar todos aquellos aspectos que surgieron durante la programación y la fase de pruebas de dicha multimedia, como por ejemplo el más importante que ha sido el utilizar un tipo de programación que permita visualizar la actividad a través de Internet entre otras muchas mejoras. Además en esta nueva aplicación se ha introducido una actividad que consiste en un simulador de la elaboración de una emulsión en donde los alumnos podrán probar diferentes parámetros de fabricación (velocidad y tiempo de agitación) para encontrar aquellos que den unas características de viscosidad y extensión lo más óptimas posibles. A día de hoy faltan todavía algunos ajustes a dicha aplicación que se pretende ensayar en el curso académico 2004-2005 donde se valorará por parte de los alumnos y profesores su aplicabilidad y su aceptación real. En esta comunicación se presenta las áreas desarrolladas.

El subsuelo de la Torre del Pretorio: substructiones de tradición helenística bajo la sede del Concilium Prouinciae Hispaniae Citerioris (Tarraco)

El artículo presenta el estudio de un área arquitectónicamente compleja, integrada dentro del denominado Foro Provincial de Tarraco . El análisis de la estratigrafía arquitectónica y de los procesos de construcción, ha representado un instrumento fundamental para la interpretación de un área caracterizada por una compleja evolución urbanística, poniendo en evidencia el desarrollo del proyecto constructivo de una obra de gran envergadura como la del Foro Provincial. Desafortunadamente, la ausencia de datos procedentes de las excavaciones arqueológicas, ha limitado la definición de una cronología absoluta exacta. El proceso de monumentalización de la cima de la colina tarraconense iniciado, según las fuentes históricas y numismáticas, en época julio-claudia, culminó en época Flavia con la finalización del complejo monumental distribuido en tres terrazas. El sector que se examina, situado junto al circo, se encuadra dentro de un sistema de substructiones que a menudo caracterizan los conjuntos forense y sacro organizados en terrazas.

An Engineering Solution for using Coarse Meshes in the Simulation of Delamination with Cohesive Zone Models

This paper presents a methodology to determine the parameters used in the simulation of delamination in composite materials using decohesion finite elements. A closed-form expression is developed to define the stiffness of the cohesive layer. A novel procedure that allows the use of coarser meshes of decohesion elements in large-scale computations is proposed. The procedure ensures that the energy dissipated by the fracture process is correctly computed. It is shown that coarse-meshed models defined using the approach proposed here yield the same results as the models with finer meshes normally used in the simulation of fracture processes

Simulation of Delamination Propagation in Composites Under High-Cycle Fatigue by Means of Cohesive-Zone Models

A damage model for the simulation of delamination propagation under high-cycle fatigue loading is proposed. The basis for the formulation is a cohesive law that links fracture and damage mechanics to establish the evolution of the damage variable in terms of the crack growth rate dA/dN. The damage state is obtained as a function of the loading conditions as well as the experimentally-determined coefficients of the Paris Law crack propagation rates for the material. It is shown that by using the constitutive fatigue damage model in a structural analysis, experimental results can be reproduced without the need of additional model-specific curve-fitting parameters

An Interface Damage Model for the Simulation of Delamination Under Variable-Mode Ratio in Composite Materials

A thermodynamically consistent damage model for the simulation of progressive delamination under variable mode ratio is presented. The model is formulated in the context of the Damage Mechanics. The constitutive equation that results from the definition of the free energy as a function of a damage variable is used to model the initiation and propagation of delamination. A new delamination initiation criterion is developed to assure that the formulation can account for changes in the loading mode in a thermodynamically consistent way. The formulation proposed accounts for crack closure effets avoiding interfacial penetration of two adjacent layers aftercomplete decohesion. The model is implemented in a finite element formulation. The numerical predictions given by the model are compared with experimental results

Blackbody emission under laser excitation of silicon nanopowder produced by plasma-enhanced chemical-vapor deposition

Previous results concerning radiative emission under laser irradiation of silicon nanopowder are reinterpreted in terms of thermal emission. A model is developed that considers the particles in the powder as independent, so under vacuum the only dissipation mechanism is thermal radiation. The supralinear dependence observed between the intensity of the emitted radiation and laser power is predicted by the model, as is the exponential quenching when the gas pressure around the sample increases. The analysis allows us to determine the sample temperature. The local heating of the sample has been assessed independently by the position of the transverse optical Raman mode. Finally, it is suggested that the photoluminescence observed in porous silicon and similar materials could, in some cases, be blackbody radiation

Gas collisions and pressure quenching of the photoluminescence of silicon nanopowder grown by plasma-enhanced chemical vapor deposition

The quenching of the photoluminescence of Si nanopowder grown by plasma-enhanced chemical vapor deposition due to pressure was measured for various gases ( H2, O2, N2, He, Ne, Ar, and Kr) and at different temperatures. The characteristic pressure, P0, of the general dependence I(P)=I0exp(-P/P0) is gas and temperature dependent. However, when the number of gas collisions is taken as the variable instead of pressure, then the quenching is the same within a gas family (mono- or diatomic) and it is temperature independent. So it is concluded that the effect depends on the number of gas collisions irrespective of the nature of the gas or its temperature

Redrawing Tarraco

The city of Tarragona houses an important architectural heritage mainly from its past as ‘Tarraco’, capital of the Roman province of Hispania Citerior, but also from its medieval and late 19th century history. The archaeological ensemble of Tarraco was inscribed as a UNESCO World Heritage Site in 2000, but although many efforts have been devoted by archaeologists and historians to unveil and understand the history and aspect of the Roman city, many aspects remain unknown. This is largely caused by the absence of a coherent body of historiographical material, which is todays cattered across several institutions and, specially, the lack of precise and useful graphical representations of the remains and of the existing city that allows in-depth analysis and interpretations of future findings. In recent years, researchers from the Catalan Institute of Classical Archaeology (ICAC) and the Architecture School of the URV (ETSA) have teamed up to produce comprehensive, detailed graphic materials, including a new set of plans and sections of the old city, of the grandiose areas of representation of the Provincial capital, and of the hidden structures beneath the city’s surface. These have been executed with the latest technologies (fotogrammetry, laser scanning) but also with traditional methods (measurement, topography), on t op of a mixture of existing materials (hand-drafted cartography from municipal master plans) and of historical and archaeological documentation.

La première génération d’écrivains d’origine amazighe dans la littérature catalane: Laila Karrouch (Nador, 1977) et Najat El Hachmi (Nador, 1979). Leur signification et valeur.

La Catalogne a accueilli entre la fin du XXe siècle et le début du XXIe siècle une importante vague d’immigrés aux origines les plus diverses. Les Marocains ont constitué le premier flot de cette vague et ont donné naissance, par le biais des oeuvres de Laila Karrouch et de Najat El Hachmi, à une littérature pionnière construite dans la tension entre deux mondes, le Maghreb et la Catalogne. Cette littérature, faite d’expériences vécues profondes, va permettre à beaucoup d’autres, à la fois, de garder leur identité et de se sentir citoyens de leur nouveau pays.

Manifiesto a favor de la enseñanza de la Geología

Manifest en defensa d'incloure la Geologia com a assignatura pròpia de la modalitat en el Batxillerat de Ciències