Interaction of Hawking radiation with static sources in deSitter and Schwarzschild-deSitter spacetimes

We study and look for similarities between the response rates $R^{\rm dS}(a_0, \Lambda)$ and $R^{\rm SdS}(a_0, \Lambda, M)$ of a static scalar source with constant proper acceleration $a_0$ interacting with a massless, conformally coupled Klein-Gordon field in (i) deSitter spacetime, in the Euclidean vacuum, which describes a thermal flux of radiation emanating from the deSitter cosmological horizon, and in (ii) Schwarzschild-deSitter spacetime, in the Gibbons-Hawking vacuum, which describes thermal fluxes of radiation emanating from both the hole and the cosmological horizons, respectively, where $\Lambda$ is the cosmological constant and $M$ is the black hole mass. After performing the field quantization in each of the above spacetimes, we obtain the response rates at the tree level in terms of an infinite sum of zero-energy field modes possessing all possible angular momentum quantum numbers. In the case of deSitter spacetime, this formula is worked out and a closed, analytical form is obtained. In the case of Schwarzschild-deSitter spacetime such a closed formula could not be obtained, and a numerical analysis is performed. We conclude, in particular, that $R^{\rm dS}(a_0, \Lambda)$ and $R^{\rm SdS}(a_0, \Lambda, M)$ do not coincide in general, but tend to each other when $\Lambda \to 0$ or $a_0 \to \infty$. Our results are also contrasted and shown to agree (in the proper limits) with related ones in the literature.Comment: ReVTeX4 file, 9 pages, 5 figure

Do static sources respond to massive scalar particles from the Hawking radiation as uniformly accelerated ones do in the inertial vacuum?

We revisit the recently found equivalence for the response of a static scalar source interacting with a {\em massless} Klein-Gordon field when the source is (i) static in Schwarzschild spacetime, in the Unruh vacuum associated with the Hawking radiation and (ii) uniformly accelerated in Minkowski spacetime, in the inertial vacuum, provided that the source's proper acceleration is the same in both cases. It is shown that this equivalence is broken when the massless Klein-Gordon field is replaced by a {\em massive} one.Comment: 4 pages, 2 figure

Modelo didáctico de profesores de enseñanza media de química : análisis de casos en el desarrollo del tema disoluciones (Santa Fe – Argentina)

La presente investigación se realizó en tres aulas de Química de Enseñanza Media (Argentina) durante el año 2008, en el marco del proyecto AECI/7510/07 entre las universidades del Litoral (Argentina) y de Santiago de Compostela (España). El propósito fue caracterizar los modelos didácticos que se ponen de manifiesto al desarrollar los docentes, una propuesta de tipo constructivista de secuencias de enseñanza para el tema Disoluciones. Con los aportes del análisis de opinión de las actividades (pre y post) realizadas por los docentes y la observación directa de las clases, se infiere que los profesores desarrollan sus clases en forma tradicional -probablemente la metodología propuesta no ha sido asimilada debido al tipo de instrucción al que están habituados el profesorado y el alumnado- aunque se observan intentos de aproximarse a modelos más constructivistas

Bacteriological conversion in twenty urinary tuberculosis patients treated with ofloxacin, rifampin and isoniazid: a 10-year follow-up study

Twenty patients withuri nary tuberculosis were treated withofloxac in (200 mg/day, 6 months), rifampin (600 mg/day, 3 months) and isoniazid (300 mg/day, 3 months) between 1989 and 1990. All patients were new cases, diagnosed by observation and/or isolation of Mycobacterium tuberculosis in one of the three morning urine samples. Bacteriological culture conversion (negativization) was assessed as a clinical guide of efficacy, comparing it, as the only parameter, against a control group (150 patients) withurina ry tuberculosis who received conventional therapy. Bacteriological follow-up studies were performed in bothgroups monthly for 6 months, then again 6 months later and then every year for 10 years after completion of treatment. In the 20 patients, the initial culture was positive with over 100 colonies per culture (>50%); the smear was positive in 45% of the patients (most were 2+). All strains were susceptible to rifampin, isoniazid and ofloxacin. Two patients discontinued treatment. Beginning withth e first monthof treatment, the bacteriological conversion was 100%, 89.5% and 100% in the remaining controls. In the control group, which received conventional treatment, the conversion was: 90%, 87%, 93% and 100% in the remaining controls. Treatment withofloxacin resulted in a bacteriological conversion similar to that following conventional treatment (p>0.05, Fisher’s exact test). After 10 years of patient follow-up, we conclude that ofloxacin, in combination withrifampin and isoniazid (bothfor 3 months only is effective against M. tuberculosis, providing satisfactory bacteriological and clinical efficacy

Una propuesta didáctica para la enseñanza de la termoquímica en 2º de Bachillerato

El presente trabajo forma parte de una investigación más amplia relacionada con el diseño, la planificación, la implementación y la evaluación de una propuesta didáctica para la enseñanza de la Termodinámica Química en 2º Bachillerato. En el marco de tal investigación, la propuesta didáctica constructivista “ Termoquímica” constituye la fase previa a la intervención de aula. El modelo de diseño, planificación y desarrollo que ha guiado la estructuración de la secuencia de actividades “Termoquímica” consta de 5 tareas: la determinación del contenido académico; la determinación de la problemática de aprendizaje; la selección, formulación y secuenciación de los objetivos de aprendizaje; la selección de estrategias de instrucción; y, por último, la selección de estrategias de evaluación

U-Pb zircon age of Ordovician magmatism in the Albera Massif (Eastern Pyrenees)

New geochronological data from the Albera Massif confirm the presence of an Early - Mid Ordovician igneous event (472 - 465Ma) recorded in the pre-Variscan rocks of the Pyrenees. This event resulted in the emplacement of a large granitic body in the lower part of the pre-Upper Ordovician metasedimentary succession and in the intrusion of a series of metric sized dykes in the middle and upper parts of it. The two types of igneous rocks were gneissified during subsequent Variscan deformation. The geochronological data confirm the occurrence of the gneiss as having derived from an Ordovician intrusive sheet, as in other Pyrenean massifs. The dykes are considered to be the subvolcanic equivalent of the intrusive sheet. The data also provide insight into the age of the metasedimentary series of the massif and enable us to correlate the dated rocks with other gneissic and subvolcanic bodies of the Variscan massifs of the Pyrenees and Iberia

Semiclassical approach to black hole absorption of electromagnetic radiation emitted by a rotating charge

We consider an electric charge, minimally coupled to the Maxwell field, rotating around a Schwarzschild black hole. We investigate how much of the radiation emitted from the swirling charge is absorbed by the black hole and show that most of the photons escape to infinity. For this purpose we use the Gupta-Bleuler quantization of the electromagnetic field in the modified Feynman gauge developed in the context of quantum field theory in Schwarzschild spacetime. We obtain that the two photon polarizations contribute quite differently to the emitted power. In addition, we discuss the accurateness of the results obtained in a full general relativistic approach in comparison with the ones obtained when the electric charge is assumed to be orbiting a massive object due to a Newtonian force.Comment: 8 pages (revtex), 8 figure

U-Pb zircon age of Ordovician magmatism in the Albera Massif (Eastern Pyrenees)

New geochronological data from the Albera Massif confirm the presence of an Early – Mid Ordovician igneous event (472 - 465Ma) recorded in the pre-Variscan rocks of the Pyrenees. This event resulted in the emplacement of a large granitic body in the lower part of the pre-Upper Ordovician metasedimentary succession and in the intrusion of a series of metric sized dykes in the middle and upper parts of it. The two types of igneous rocks were gneissified during subsequent Variscan deformation. The geochronological data confirm the occurrence of the gneiss as having derived from an Ordovician intrusive sheet, as in other Pyrenean massifs. The dykes are considered to be the subvolcanic equivalent of the intrusive sheet. The data also provide insight into the age of the metasedimentary series of the massif and enable us to correlate the dated rocks with other gneissic and subvolcanic bodies of the Variscan massifs of the Pyrenees and Iberia

Arte de la Edad del Bronce: Los grabados rupestres de Cova da Bruxa y Laxe das Rodas (Muros, A Coruña): Actuación aqueológica y revisión intrepretativa

This article provides the results achieved in the fieldwork and subsequents study of the petroglyphs of Laxe das Rodas and Cova da Bruxa (Muros, A Coruña), after the developement of the research projects “Domumentación e rexistro da estación rupestre da Laxe das Rodas”, and “Proxecto de domumentación, de rexistro e de acondicionamento do entorno da estación rupestre de Laxe das Rodas (Muros, A Coruña)”, of the History Departament at the University of Santiago de Compostela, the municipality of Muros, and the Comunidad Autónoma of Galicia (Xunta de Galicia), with the collaboration the Area of Prehistory of the University of Murcia.Este artículo ofrece los resultados obtenidos en los trabajos de campo y posterior estudio de los conjuntos grabados de Laxe das Rodas y Cova da Bruxa (Muros, A Coruña), tras el desarrollo de los proyectos de investigación: “Domumentación e rexistro da estación rupestre da Laxe das Rodas” y “Proxecto de domumentación, de rexistro e de acondicionamento do entorno da estación rupestre de Cova da Bruxa (Serres, A Coruña)”, en los que participaron el Grupo de Estudos para a Prehistoria do Noroeste Ibérico (GEPN), del Departamento de Historia I de la Facultad de Geografía e Historia de la Universidad de Santiago de Compostela, el Concello de Muros y la Xunta de Galicia, con la colaboración en la dirección científica del Área de Prehistoria de la Universidad de Murcia