Pauli distorted double folded potential

The enhancement in the production of even-Z nuclei observed in nuclear fission has also been observed in fragments produced from heavy ion collsions. Beams of 40Ar, 40Cl, and 40Ca at 25 MeV/nucleon were impinged on 58Fe and 58Ni targets. The resulting fragments were detected using the MSU 4pi detector array, which had additional silicon detectors for better isotopic resolution. Comparison of the ratios of yields for each element showed enhancement of even-Z fragment production. The enhancement was more pronounced for reactions with a greater difference in the N/Z of the compound system. However, this effect was less for systems that were more neutron rich. The average N/Z for fragments also displayed an odd-even effect with a lower average N/Z for the even-Z fragments. This is related to the greater availability of neutron-poor isotopes for even-Z nuclei

Spin polarized neutron matter and magnetic susceptibility within the Brueckner-Hartree-Fock approximation

The Brueckner-Hartree-Fock formalism is applied to study spin polarized neutron matter properties. Results of the total energy per particle as a function of the spin polarization and density are presented for two modern realistic nucleon-nucleon interactions, Nijmegen II and Reid93. We find that the dependence of the energy on the spin polarization is practically parabolic in the full range of polarizations. The magnetic susceptibility of the system is computed. Our results show no indication of a ferromagnetic transition which becomes even more difficult as the density increases.

Isospin-rich nuclei in neutron star matter

Stability of nuclei beyond the drip lines in the presence of an enveloping gas of nucleons and electrons, as prevailing in the inner crust of a neutron star, is studied in the temperature-dependent Thomas-Fermi framework. A limiting asymmetry in the isospin space beyond which nuclei cannot exist emerges from the calculations. The ambient conditions such as temperature, baryon density, and neutrino concentration under which these exotic nuclear systems can be formed are studied in some detail.

Atomic parity nonconservation, neutron radii, and effective field theories of nuclei

Accurately calibrated effective field theories are used to compute atomic parity nonconserving (APNC) observables. Although accurately calibrated, these effective field theories predict a large spread in the neutron skin of heavy nuclei. Whereas the neutron skin is strongly correlated to numerous physical observables, in this contribution we focus on its impact on new physics through APNC observables. The addition of an isoscalar-isovector coupling constant to the effective Lagrangian generates a wide range of values for the neutron skin of heavy nuclei without compromising the success of the model in reproducing well-constrained nuclear observables. Earlier studies have suggested that the use of isotopic ratios of APNC observables may eliminate their sensitivity to atomic structure. This leaves nuclear structure uncertainties as the main impediment for identifying physics beyond the standard model. We establish that uncertainties in the neutron skin of heavy nuclei are at present too large to measure isotopic ratios to better than the 0.1% accuracy required to test the standard model. However, we argue that such uncertainties will be significantly reduced by the upcoming measurement of the neutron radius in 208^Pb at the Jefferson Laboratory.

Ferromagnetic instabilities in neutron matter at finite temperature with the Skyrme interaction

The properties of spin-polarized neutron matter are studied at both zero and finite temperature using Skyrme-type interactions. It is shown that the critical density at which ferromagnetism takes place decreases with temperature. This unexpected behavior is associated to an anomalous behavior of the entropy that becomes larger for the polarized phase than for the unpolarized one above a certain critical density. This fact is a consequence of the dependence of the entropy on the effective mass of the neutrons with different third spin component. A new constraint on the parameters of the effective Skyrme force is derived if this behavior is to be avoided.

Maximum mass of neutron stars

We determine the structure of neutron stars within a Brueckner-Hartree-Fock approach based on realistic nucleon-nucleon, nucleon-hyperon, and hyperon-hyperon interactions. Our results indicate rather low maximum masses below 1.4 solar masses. This feature is insensitive to the nucleonic part of the EOS due to a strong compensation mechanism caused by the appearance of hyperons and represents thus strong evidence for the presence of nonbaryonic "quark" matter in the interior of heavy stars.

Pionic branches in neutron matter and the problem of pion condensation

The pion spectrum for charged and neutral pions is investigated in pure neutron matter, by letting the pions interact with a neutron Fermi sea in a self-consistent scheme that renormalizes simultaneously the mesons, considered the source of the interaction, and the nucleons. The possibility of obtaining different kinds of pion condensates is investigated with the result that they cannot be reached even for values of the spin-spin correlation parameter, g', far below the range commonly accepted.

Development of selected electro-active polymer-ceramic nanocomposites as pyroelectric thermal/infrared detector materials

The present work emphasises on the synthesis and characterization of electro-active polymer-ceramic nanocomposites which can be used for pyroelectric thermal/infrared detection applications. Two sets of samples belong to polymer-microcrystalline composites have also been investigated in the work. The polymers used in the work have been commercially available ones, but the nanoceramics have been synthesized following simple chemical routes and aqueous organic gel routes. After characterizing the nanoceramics for their structure by powder XRD, they have been dispersed in liquid polymer and sonicated for uniform dispersion. The viscous mixture so formed was cast in the form of films for experimentation. Samples with volume fraction of the ceramic phase varied from 0 to 0.25 have been prepared. Solution growth was followed to prepare microcrystalline samples for the polymer-microcrystalline composites. The physical properties that determine the pyroelectric sensitivity of a material are dielectric constant, dielectric loss, pyroelectric coefficient, thermal conductivity and specific heat capacity. These parameters have been determined for all the samples and compositions reported in this work.The pyroelectric figures of merit for all the samples were determined. The pyroelectric figures of merit that determine the pyroelectric sensitivity of a material are current sensitivity, voltage responsivity and detectivity. All these have been determined for each set of samples and reported in the thesis. In order to assess the flexibility and mouldability of the composites we have measured the Shore hardness of each of the composites by indentation technique and compared with the pyroelectric figures of merit. Some important factors considered during the material fabrication stages were maximum flexibility and maximum figures of merit for pyroelectric thermal/IR detection applications. In order to achieve these goals, all the samples are synthesized as composites of polymers and nano/microcrystalline particles and are prepared in the form of freestanding films. The selected polymer matrices and particle inclusions possess good pyroelectric coefficients, low thermal and dielectric properties, so that good pyroelectric figures of merit could be achieved. The salient features of the work include the particle size of the selected ceramic materials. Since they are in nanometer size it was possible to achieve high flexibility and moldability with high figures of merit for even low volume fractions of inclusions of the prepared nanocrystalline composites. In the case of microcrystalline TGS and DTGS, their composites in PU matrix protect them from fragility and humidity susceptibility and made them for environmental friendly applications.

El test Bender como detector de problemas emocionales y comportamentales en niños de cuarto y quinto de primaria

Determinar si el test de Bender puede discriminar, en niños de cuarto y quinto de primaria, problemas emocionales y comportamentales y poder establecer un diagnóstico diferencial. Los objetivos específicos se agrupan en tres bloques: 1.- El Test de Bender y variables sociodemográficos. 2.- El test de Bender como prueba madurativa. 3.- El test de Bender como técnica proyectiva. Con el fin de dar respuestas a los objetivos planteados se formula una serie de hipótesis que orientan el análisis de los resultados. Esta investigación consiste en un estudio descriptivo correlacional. Se realiza mediante la aplicación del test Gestáltico Visomotor de Bender. Se trata de una investigación básicamente descriptiva y correlacional, donde se han seleccionado sujetos de diferentes edades (9-11 años) evaluados en un solo momento temporal. Las variables que se han utilizado, se han clasificado en variables sociodemográificas y psicológicas. La población la componen los alumnos de cuarto y quinto de primaria de la población de Huelva, capital y provincia. La elección de los distintos colegios se ha realizado teniendo en cuenta el nivel socioeconómico y profesional de los padres. La muestra está constituida por 722 sujetos de los cuales el 49,8 por ciento corresponde a varones y el 50,1 por ciento a mujeres, escolarizado en colegios públicos y concertados pertenecientes a Huelva capital y periferia. La selección de los instrumentos de medida se establece el criterio de que sean técnicas fiables, asequibles y fáciles de aplicar : Prueba de maduración visomotora: Test Bender. Prueba de capacidad intelectual: Test de Factor 'G' de R. B. Cattell y A. K. S. Cattell (Escala 2, Forma A). Cuestionario de Personalidad para niños EPQ-J De H. J. Eysenck y S. B. G. Eysenck. Cuestionario de autoevaluación Ansiedad estado-rasgo en niños, de C. D. Spielberg et al. Cuestionario para el profesor tutor. El test de Bender se podría emplear como screening para detectar desajustes madurativos que pueden tener como consecuencias problemas emocionales y posibles conductas antisociales, pero no es válido para detectar patologías diferenciales como la ansiedad, neuroticismo y psicoticismo. Se puede considerar esta prueba como un complemento de las técnicas psicométricas y así proporcionar, no sólo una visión analítica, sino una perspectiva más global de la persona. Sin embargo, en la utilización del test de Bender como test de personalidad se deben tener en cuenta los siguientes planteamientos: a. Aplicarlo de forma individual. b. Conveniencia de tener una pequeña entrevista con el niño. c. Es aconsejable que el evaluador tenga experiencia en el manejo de pruebas proyectivas y amplios conocimientos de psicopatología infantil. d. Así mismo, es muy importante que el evaluador tenga cierto entrenamiento y experiencia con el test de Bender. Es importante seguir investigando los índices que se asocian a conductas disruptivas y asociales, pues parece que es donde se han obtenido más relaciones y quizás en un futuro pueda ser utilizada de manera preventiva.

Laser stripe peak detector for 3D scanners: a FIR filter approach

The accuracy of a 3D reconstruction using laser scanners is significantly determined by the detection of the laser stripe. Since the energy pattern of such a stripe corresponds to a Gaussian profile, it makes sense to detect the point of maximum light intensity (or peak) by computing the zero-crossing point of the first derivative of such Gaussian profile. However, because noise is present in every physical process, such as electronic image formation, it is not sensitive to perform the derivative of the image of the stripe in almost any situation, unless a previous filtering stage is done. Considering that stripe scanning is an inherently row-parallel process, every row of a given image must be processed independently in order to compute its corresponding peak position in the row. This paper reports on the use of digital filtering techniques in order to cope with the scanning of different surfaces with different optical properties and different noise levels, leading to the proposal of a more accurate numerical peak detector, even at very low signal-to-noise ratios

El detector de colors. 'El detector de colores'.

Resumen del vídeo en catalán

Tecnología. Construcción de un detector de humedad.

En la cub.: Secundaria. Acompañado de : Tecnología. Estructura