30,580 research outputs found
Quantum Electrodynamics vacuum polarization solver
The self-consistent modeling of vacuum polarization due to virtual
electron-positron fluctuations is of relevance for many near term experiments
associated with high intensity radiation sources and represents a milestone in
describing scenarios of extreme energy density. We present a generalized
finite-difference time-domain solver that can incorporate the modifications to
Maxwell's equations due to vacuum polarization. Our multidimensional solver
reproduced in one dimensional configurations the results for which an analytic
treatment is possible, yielding vacuum harmonic generation and birefringence.
The solver has also been tested for two-dimensional scenarios where finite
laser beam spot sizes must be taken into account. We employ this solver to
explore different types of counter-propagating configurations that can be
relevant for future planned experiments aiming to detect quantum vacuum
dynamics at ultra-high electromagnetic field intensities
Modified spinning black holes
In the context of f(R) modified gravity theories we determine that the black
holes existence is determined by the sign of a parameter dependent of the mass,
the charge, the spin and the scalar curvature. We obtain the different
astrophysical objects derived from the presence of different horizons.
Thermodynamics for this kind of black holes is studied for negative values of
the curvature, revealing that we can distinguish between two kinds of BH: fast
and slow.Comment: 4 pages, 6 figures, Contribution to the ERE2011 Spanish Relativity
Meeting, Madrid 201
A Rash Decision. The Hazards of the Wrongful Use of Adrenaline
Anaphylaxis is life-threatening and should be addressed urgently. Its treatment is not without side effects and an accurate diagnosis must be made to prevent potential harm by the wrongful use of medication. A 46-year-old woman with hypertension treated with angiotensin converting enzyme inhibitor (ACEI) presented to the emergency department with non-pitting oedema of the face and limbs. A hasty diagnosis of anaphylaxis was made and intravenous adrenaline administered. The patient developed a myocardial infarction caused by coronary artery spasm that required invasive intervention. The initial clinical picture was resolved when the ACEI was discontinued unmasking a case of ACEI-induced angioedema. The correct differentiation of these two apparently similar clinical entities is of utmost importance in the management of emergency department patients.info:eu-repo/semantics/publishedVersio
Racionalidades campesinas en los Andes del Sur : reflexiones en torno al cultivo de la quinua y otros vegetales andinos
International audienceThis book originated in a workshop organised in La Paz (Bolivia) in December 2008, as part of the Franco-Bolivian ANR-EQUECO programme, with the aim of reflecting on socio-environmental changes in agriculture in the southern Andes over the last 1,000 years. Subsequently, as a result of international collaborations, including the Franco-Argentine ECOS programme, the editors invited other experts to contribute their work to these reflections. The authors of this book - archaeologists, anthropologists, geographers, geneticists, agronomists and ecologists - represent a balanced panel of human and biophysical sciences. All have direct and recent experience of the current or past reality of the societies and natural environment of the Southern Andes. Despite the diversity of their respective disciplines and perspectives, the authors have endeavoured to make their contributions accessible to a non-specialist audience, presenting tables and figures to facilitate understanding of the data and using a glossary to define, where necessary, certain technical or vernacular terms. The temporal scope of the book covers pre-Hispanic periods to the present, while geographically, it covers the southern altiplano and inter-Andean valleys of southern Bolivia, the puna and valleys of northwestern Argentina, and the contrasting regions of Chile.Este libro tuvo su origen en un taller cuyo objetivo fue reflexionar sobre los cambios socio ambientales en la agricultura del sur andino en los últimos 1.000 años, encuentro organizado en La Paz (Bolivia) en diciembre de 2008, en el marco del programa franco-boliviano EQUECO. Luego, como fruto de colaboraciones internacionales entre ellas el programa franco-argentino ECOS, los editores invitaron a otros expertos más para que aporten con sus trabajos a estas reflexiones.Los autores de este libro –arqueólogos, antropólogos, geógrafos, genetistas, agrónomos y ecólogos– representan un panel equilibradoentre ciencias humanas y biofísicas. Todos cuentan con una experiencia directa y reciente de la realidad actual o pasada de las sociedades y del ambiente natural de los Andes del Sur. A pesar de la diversidad de sus respectivas disciplinas y perspectivas, los autores se aplicaron en hacer sus contribuciones accesibles al público no especializado, presentando tablas y figuras que faciliten la comprensión de los datos y utilizando un glosario para definir, cuando necesario, ciertos términos técnicos o vernaculares. El alcance temporal del libro cubre desde los períodos prehispánicos hasta el presente mientras que en lo geográfico, recorre desde el altiplano sur y los valles interandinos del sur de Bolivia, hasta la puna y los valles del noroeste de Argentina pasando por las contrastadas regiones de Chile
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