Magnetic Surfaces in Stationary Axisymmetric General Relativity

In this paper a new method is derived for constructing electromagnetic surface sources for stationary axisymmetric electrovac spacetimes endowed with non-smooth or even discontinuous Ernst potentials. This can be viewed as a generalization of some classical potential theory results, since lack of continuity of the potential is related to dipole density and lack of smoothness, to monopole density. In particular this approach is useful for constructing the dipole source for the magnetic field. This formalism involves solving a linear elliptic differential equation with boundary conditions at infinity. As an example, two different models of surface densities for the Kerr-Newman electrovac spacetime are derived.Comment: 15 page

Etapas de desarrollo en la planta de frijol

The developmental scale of the bean crop and the general characteristics of plant development are described on the basis of morphological and physiological changes in the plant. The factors influencing the duration of the developmental stages of beans are identified, namely growth habit, earliness, and climate. (CIAT)Se describen las etapas de la escala del desarrollo del cultivo de frijol y las caracteristicas generales del desarrollo de la planta con base en los cambios morfologicos y fisiologicos de la misma. Se identifican los factores que influyen en la duracion de las etapas de desarrollo del frijol: habito de crecimiento, precocidad y clima. (CIAT

Genomic Evolution of Two Acinetobacter baumannii Clinical Strains from ST-2 Clones Isolated in 2000 and 2010 (ST-2_clon_2000 and ST-2_clon_2010)

Acinetobacter baumannii is a successful nosocomial pathogen due to its ability to persist in hospital environments by acquiring mobile elements such as transposons, plasmids, and phages. In this study, we compared two genomes of A. baumannii clinical strains isolated in 2000 (ST-2_clon_2000) and 2010 (ST-2_clon_2010) from GenBank project PRJNA308422

Sphere rolling on the surface of a cone

We analyse the motion of a sphere that rolls without slipping on a conical surface having its axis in the direction of the constant gravitational field of the Earth. This nonholonomic system admits a solution in terms of quadratures. We exhibit that the only circular of the system orbit is stable and furthermore show that all its solutions can be found using an analogy with central force problems. We also discuss the case of motion with no gravitational field, that is, of motion on a freely falling cone.Comment: 12 pages, 2 figures, to be published in Eur J Phy

Transient Propagation and Scattering of Quasi-Rayleigh Waves in Plates: Quantitative comparison between Pulsed TV-Holography Measurements and FC(Gram) elastodynamic simulations

We study the scattering of transient, high-frequency, narrow-band quasi-Rayleigh elastic waves by through-thickness holes in aluminum plates, in the framework of ultrasonic nondestructive testing (NDT) based on full-field optical detection. Sequences of the instantaneous two-dimensional (2-D) out-of-plane displacement scattering maps are measured with a self-developed PTVH system. The corresponding simulated sequences are obtained by means of an FC(Gram) elastodynamic solver introduced recently, which implements a full three-dimensional (3D) vector formulation of the direct linear-elasticity scattering problem. A detailed quantitative comparison between these experimental and numerical sequences, which is presented here for the first time, shows very good agreement both in the amplitude and the phase of the acoustic field in the forward, lateral and backscattering areas. It is thus suggested that the combination of the PTVH system and the FC(Gram) elastodynamic solver provides an effective ultrasonic inspection tool for plate-like structures, with a significant potential for ultrasonic NDT applications.Comment: 46 pages, 16 figures, corresponding author Jos\'e Carlos L\'opez-V\'azquez, [email protected]. Changes: 1st, 4th, 5th paragraphs (intro), 3rd, 4th paragraphs (sec. 4); [59-60] cited only in appendixes; old ref. [52] removed; misprints corrected in the uncertainty of c_L (subsec. 3.1), citation to fig. 10 (sec. 4), size of images (caption fig.15); reference to Lam\'e constants removed in subsec. 3.

Calizas de Triacastela, materia prima para la fabricación de cemento

[Resumen] Los niveles de producción y consumo actual de cemento; las exportaciones, en las que España en los últimos años ha adquirido el primer puesto, exigen un tamaño mínimo necesario de las factorias para lograr un nivel de costo razonable. El calcio ha sido el principal componente del cemento y, por consideraciones científicas, podernos estar seguros que mañana también lo será. En Galicia aparece en pocos lugares, en cantidades muy limitadas y en ocasiones con carbonato magnésico. Don Isidro Parga ha tenido el mérito de aportar una solución; la cantera de Triacastela. En este trabajo se describe su importante volumen (más de 100 millones de toneladas), su idónea composición química, las posibilidades de lograr unos costos de extracción muy favorables y los resultados experimentales logrados en los dos primeros años de explotación[Résumé] Le niveau de production et de consomation actuel de ciment, de même que les exportations, ou l'Espagne a atteint la premiere place ces dernieres années, exigent un volume minimun nécessaire des usines a ciment pour parvenir a un niveau de frais raisonnable. Le calcium a été le compossant principal du ciment et, par des considerations scientifiques, nous pouvons affirmer qu'il continuera a l'otre. En Galice il n'apparalt que rarement et dans des can tités tres limitées, meme parfois contenant du carbonate de magnesium. Mr. Isidro Parga a eu le mérite d'apporter une solution; la carriere de Triacastela. Dans cet étude on y voit décrit sa grande Quantité (plus de 100 Millions de Tm.), son adéquate composition chimique, la possibilité de réussir des frais d'extraction tres favorables et les resultats expérimentaux atteints durant les deux premieres années d'exploitatio

Numerical modeling and measurement by pulsed television holography of ultrasonic displacement maps in plates with through-thickness defects

We present a novel numerical modeling of ultrasonic Lamb and Rayleigh wave propagation and scattering by through-thickness defects like holes and slots in homogeneous plates, and its experimental verification in both near and far field by a self-developed pulsed TV holography system. In contrast to rigorous vectorial formulation of elasticity theory, our model is based on the 2-D scalar wave equation over the plate surface, with specific boundary conditions in the defects and plate edges. The experimental data include complex amplitude maps of the out-of-plane displacements of the plate surface, obtained by a two-step spatiotemporal Fourier transform method. We find a fair match between the numerical and experimental results, which allows for quantitative characterization of the defects

Morphological taphonomic transformations of fossil bones in continental environments, and repercussions of their chemical composition

The aim of this paper is to provide a summary of structural or surface modifications of vertebrate bone remains in continental palaeoenvironments that may have repercussions on their chemical composition. Both before and after burial, a different set of physical, chemical and biological agencies may produce modifications of the bone morphological structure and/or bone chemical composition. Several of these morphological modifications are diagnostic of particular agents, which otherwise may not be noticed or identified in a fossil association. In order to understand diagenesis, those events that occurred before final burial have to be considered, as they may strongly modify the bone morphological structure and influence post-burial changes