Nagel scaling and relaxation in the kinetic Ising model on a n-isotopic chain

The kinetic Ising model on a n-isotopic chain is considered in the framework of Glauber dynamics. The chain is composed of N segments with n sites, each one occupied by a different isotope. Due to the isotopic mass difference, the n spins in each segment have different relaxation times in the absence of the interactions, and consequently the dynamics of the system is governed by multiple relaxation mechanisms. The solution is obtained in closed form for arbitrary n, by reducing the problem to a set of n coupled equations, and it is shown rigorously that the critical exponent z is equal to 2. Explicit results are obtained numerically for any temperature and it is also shown that the dynamic susceptibility satisfies the new scaling (Nagel scaling) proposed for glass-forming liquids. This is in agreement with our recent results (L. L. Goncalves, M. Lopez de Haro, J. Taguena-Martinez and R. B. Stinchcombe, Phys. Rev. Lett. 84, 1507 (2000)), which relate this new scaling function to multiple relaxation processes.Comment: 4 pages, 2 figures, presented at Ising Centennial Colloquium, to be published in the Proceedings (Brazilian Journal of Physics.

Qualitative study in Loop Quantum Cosmology

This work contains a detailed qualitative analysis, in General Relativity and in Loop Quantum Cosmology, of the dynamics in the associated phase space of a scalar field minimally coupled with gravity, whose potential mimics the dynamics of a perfect fluid with a linear Equation of State (EoS). Dealing with the orbits (solutions) of the system, we will see that there are analytic ones, which lead to the same dynamics as the perfect fluid, and our goal is to check their stability, depending on the value of the EoS parameter, i.e., to show whether the other orbits converge or diverge to these analytic solutions at early and late times.Comment: 12 pages, 7 figures. Version accepted for publication in CQ

Multicomponent fluids of hard hyperspheres in odd dimensions

Mixtures of hard hyperspheres in odd space dimensionalities are studied with an analytical approximation method. This technique is based on the so-called Rational Function Approximation and provides a procedure for evaluating equations of state, structure factors, radial distribution functions, and direct correlations functions of additive mixtures of hard hyperspheres with any number of components and in arbitrary odd-dimension space. The method gives the exact solution of the Ornstein--Zernike equation coupled with the Percus--Yevick closure, thus extending to arbitrary odd dimension the solution for hard-sphere mixtures [J. L. Lebowitz, Phys.\ Rev.\ \textbf{133}, 895 (1964)]. Explicit evaluations for binary mixtures in five dimensions are performed. The results are compared with computer simulations and a good agreement is found.Comment: 16 pages, 8 figures; v2: slight change of notatio

Quasar 3C 298: a test-case for meteoritic nanodiamond 3.5 µm emission

Aims. We calculate the dust emission expected at 3.43 and 3.53 µm if meteoritic (i.e. hydrogenated) nanodiamonds are responsible for most of the far-UV break observed in quasars. Methods. We integrate the UV flux that hydrogenated nanodiamonds must absorb to reproduce the far-UV break. Based on laboratory spectra of H-terminated diamond surfaces, we analyse the radiative energy budget and derive theoretically the IR emission profiles expected for possible C-H surface stretch modes of the diamonds. Results. Using as test case a spectrum of 3C 298 provided by the Spitzer Observatory, we do not find evidence of these emission bands. Conclusions. While diamonds without surface adsorbates remain a viable candidate for explaining the far-UV break observed in quasars, hydrogenated nanodiamonds appear to be ruled out, as they would give rise to IR emission bands, which have not been observed so far

Gravity in the 3+1-Split Formalism II: Self-Duality and the Emergence of the Gravitational Chern-Simons in the Boundary

We study self-duality in the context of the 3+1-split formalism of gravity with non-zero cosmological constant. Lorentzian self-dual configurations are conformally flat spacetimes and have boundary data determined by classical solutions of the three-dimensional gravitational Chern-Simons. For Euclidean self-dual configurations, the relationship between their boundary initial positions and initial velocity is also determined by the three-dimensional gravitational Chern-Simons. Our results imply that bulk self-dual configurations are holographically described by the gravitational Chern-Simons theory which can either viewed as a boundary generating functional or as a boundary effective action.Comment: 25 pages; v2: minor improvements, references adde

The Capacity and Interference Statistics of High Car Traffic W-CDMA Street Cross-Shaped Micro-Cells (Uplink Analysis),

Since interference is related to the capacity and performance of W-CDMA system, it is necessary to investigate the interference characteristics (the mean value and the variance). Thus, the uplink capacity and the interference statistics of the sectors of the cross-shaped W-CDMA microcell have been analyzed using geometry with 17 microcells. A single slope propagation model with a lognormal shadowing factor has been used in the analysis. The cells have been assumed to exist in city streets with high car traffic. The capacity and the interference statistics of the sectors have been studied for different sector ranges, and different side-lobe level. The results show that the capacity increases with the increment of the sector range and with the reduction of the side-lobe level of the antennas used

A New Quasi-Optimum Power Control Scheme for Downlink in W-CDMA Macro Cellular System

The downlink power control problem in W-CDMA is studied using a new proposed model. The downlink cell capacity is given for the old model given by Gejji and our new model. A capacity increase of 16 % for the special case = 0 (no orthogonality between users) and a generalization of the old model in terms of the propagation exponent and orthogonality factor is introduced

Does swimming styles specialization influence the hamstring muscle extensibility?

El objetivo de este estudio es comprobar si el estilo de natación en el que están especializados los nadadores, influye sobre la extensibilidad isquiosural de los deportistas que han participado en esta investigación. El test empleado para este trabajo es el test “sit and reach”. Se ha medido la extensibilidad isquiosural de todos los nadadores (N=36) de ambos sexos, que entrenan en un centro de tecnificación acuático español. La edad de los participantes del estudio oscila entre los 13 y los 17 años. Esta población de nadadores ha sido dividida en cuatro grupos diferentes, dependiendo del estilo de natación en el que están especializados (crol, espalda, braza y mariposa). Para conocer la influencia del estilo natación sobre los resultados obtenidos en el test “sit and reach”, se ha aplicado un test inicial y nueve meses más tarde un test final, lo que ha permitido conocer también la evolución de las mediciones Como conclusión, la extensibilidad isquiosural y su evolución, no está condicionada por el estilo de natación en el que están especializados los nadadores que han participado en este estudioThe aim of this research is to verify the swimming style in which swimmers are specialized, have has influences hamstring extensibility athletes who have had participated in this research. The employed test for this work was the “sits and reach" test. It was measured hamstring extensibility of all swimmers (N = 36) of both sexes, who train in Spanish aquatic center modernization. The age of the study participants is between 13 and 17 years. This population of swimmers has been divided into four different groups, depending on the style of swimming in which they are specialized (crawl, backstroke, breaststroke and butterfly). To determine the influence of swimming style on the results obtained in the test "sit and reach", it having had applied an initial test before, and a final test nine months later, which have had permitted also know the measurements evolution. In conclusion, the hamstring muscle extensibility and its evolution have had being not conditioned by swimming style of the swimmer