Gravitational field around a time-like current-carrying screwed cosmic string in scalar-tensor theories

In this paper we obtain the space-time generated by a time-like current-carrying superconducting screwed cosmic string(TCSCS). This gravitational field is obtained in a modified scalar-tensor theory in the sense that torsion is taken into account. We show that this solution is comptible with a torsion field generated by the scalar field $\phi$. The analysis of gravitational effects of a TCSCS shows up that the torsion effects that appear in the physical frame of Jordan-Fierz can be described in a geometric form given by contorsion term plus a symmetric part which contains the scalar gradient. As an important application of this solution, we consider the linear perturbation method developed by Zel'dovich, investigate the accretion of cold dark matter due to the formation of wakes when a TCSCS moves with speed $v$ and discuss the role played by torsion. Our results are compared with those obtained for cosmic strings in the framework of scalar-tensor theories without taking torsion into account.Comment: 21 pages, no figures, Revised Version, presented at the "XXIV- Encontro Nacional de Fisica de Particulas e Campos ", Caxambu, MG, Brazil, to appear in Phys. Rev.

Durabilidad y propiedades mecánicas de los hormigones con filer calizo utilizando empaquetamiento de partículas

This study aims to present alternatives to reduce the demand of cement in concrete production based on particle packing concepts. Physical and mechanical characteristics of concretes, as well as the resistance to chlorides action were analyzed. The tests conducted in this study included compressive strength, chloride migration, capillary absorption tests and wetting and drying cycles in 1M sodium chloride solution. Mixtures containing limestone filler presented satisfactory results compared to the reference mixture with particle packing. Excellent results were obtained for concrete with cement consumption of 253.34 kg.m-3 in terms of compressive strength, binder index, capillary absorption and depassivation time of rebars, thus reinforcing the concept that partial cement replacement by limestone filler yields positive results in these properties. Worse results were obtained for concrete with a cement consumption of 161.86 kg.m-3, because it had a higher proportion of filler than cement. The electrochemical monitoring of the steel bars also shows that the packing of the aggregates was essential to delay the initiation of corrosion.Este estudio tiene el objetivo de presentar alternativas para reducir la demanda de cemento en la producción de hormigón teniendo en cuenta conceptos de empaquetamiento de partículas. y la resistencia a la acción de los cloruros fueron evaluados. Las pruebas realizadas en ese estudio fueron resistencia a la compresión axial, migración de cloruros, absorción capilar y ciclos de humectación y secado en solución de cloruro sódico 1M. Las mezclas que contienen filer calizo presentaron resultados satisfactorios en comparación con la mezcla de referencia con empaquetamiento de partículas. La mezcla con un consumo de cemento de 253,34 kg.m-3 demostró excelentes resultados en términos de resistencia a la compresión axial, índice de aglomerante, absorción capilar y tiempo para despasivación del acero, reforzando el concepto de que la sustitución parcial del cemento por filer calizo produce resultados positivos en esas propiedades. Peores resultados fueron obtenidos para el hormigón con consumo de cemento de 161,86 kg·m-3, debido a su composición con mayor proporción de filer en comparación con el cemento. El monitoreo electroquímico de las barras de acero muestra que el empaquetamiento de los agregados fue esencial para el retardo de la iniciación de la corrosión

Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory

Atmospheric parameters, such as pressure (P), temperature (T) and density, affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a ~10% seasonal modulation and ~2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of pressure and density. The former affects the longitudinal development of air showers while the latter influences the Moliere radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory.Comment: 24 pages, 9 figures, accepted for publication in Astroparticle Physic

Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter

Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{$6\times 10^{19}$eV}. The anisotropy was measured by the fraction of arrival directions that are less than $3.1^\circ$ from the position of an active galactic nucleus within 75 Mpc (using the V\'eron-Cetty and V\'eron $12^{\rm th}$ catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is $(38^{+7}_{-6})$, compared with $21$ expected for isotropic cosmic rays. This is down from the early estimate of $(69^{+11}_{-13})$. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201

Evaluation method for identification of tail blocking in horses

ABSTRACT This study aims to standardize the clinical and complementary examination using surface electromyography (EMG) to assess the neuromuscular function of the equine tail. Firstly, clinical examinations of the tails and EMG measurements were performed on ten healthy animals without any tail interference or manipulation. This initial experiment aimed to establish a baseline for clinical examination and EMG results. The animals underwent tail nerve plexus blockade in the second experiment using an anesthetic agent. The objective compares the clinical examination and EMG findings between the anesthetized and non-manipulated tails. Finally, two animals were used in the third experiment, where peripheral infiltration of the tail nerve plexuses was performed using a neurolytic agent. The study successfully obtained a pattern for the clinical examination of a healthy equine tail and established a pattern for the clinical examination of a tail after infiltration with anesthetic and neurolytic agents. Significant differences were observed in the clinical examination before and after the application of local anesthesia, as well as in the EMG values before and after local infiltration with anesthetic (P=0.04) and neurolytic agent (P=0.03). The presented study introduces a clinical examination protocol that utilizes surface electromyography as a diagnostic tool for cauda equina block

The Fluorescence Detector of the Pierre Auger Observatory

The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions.Comment: 53 pages. Submitted to Nuclear Instruments and Methods in Physics Research Section

Search for First Harmonic Modulation in the Right Ascension Distribution of Cosmic Rays Detected at the Pierre Auger Observatory

We present the results of searches for dipolar-type anisotropies in different energy ranges above $2.5\times 10^{17}$ eV with the surface detector array of the Pierre Auger Observatory, reporting on both the phase and the amplitude measurements of the first harmonic modulation in the right-ascension distribution. Upper limits on the amplitudes are obtained, which provide the most stringent bounds at present, being below 2% at 99% $C.L.$ for EeV energies. We also compare our results to those of previous experiments as well as with some theoretical expectations.Comment: 28 pages, 11 figure