Notas sobre la reforma educativa de 1968.

El presente artículo constituye una aproximación a una de las reformas más importantes de la educación salvadoreña, implementada a partir de 1967. Destaca la influencia de la estrategia del planeamiento educativo en dicha reforma, así como visualiza los cambios educativos en la perspectiva histórica, realizando un breve recorrido por la evolución y transformación del sistema educativo desde el siglo XIX

Successful Projects - What Makes Them Work? A Cross-National Analysis

[Excerpt] This cross national analysis is based on national studies made by research teams in India, Kenya, Romania and South Africa. It aims to draw out the lessons learnt from successful social development processes in these countries. In each country, studies have been made of projects identified as interesting, successful and/or outstanding in the way they have improved the quality of life of people with intellectual disabilities. In national reports, the respective teams have made their own national conclusions. This comparative report briefly describes the national studies. It then continues with a cross national analysis attempting to identify circumstances or factors that are common to these successful projects. Finally, the report summarises the conclusions and their implications. We hope that the findings presented in the report will be used as inspiration in future planning, implementation and funding of projects aiming at improving life conditions of groups that are marginalised in society. Chapter 1 and 2, describing the research process and the national reports have been written by Annika and Lennart Nilsson. Anders Gustavsson and Johans Sandvin are responsible for the cross national analysis in chapter 3 to 7. The conclusions and implications in chapter 8 have been written jointly. The study has been commissioned by Inclusion International and financed by the Swedish International Development Agency (Sida)

Critical behavior of ferromagnetic pure and random diluted nanoparticles with competing interactions: variational and Monte Carlo approaches

The magnetic properties and critical behavior of both ferromagnetic pure and metallic nanoparticles having concurrently atomic disorder, dilution and competing interactions, are studied in the framework of an Ising model. We have used both the free energy variational principle based on the Bogoliubov inequality and Monte Carlo simulation. As a case of study for random diluted nanoparticles we have considered the Fe$_{0.5}$Mn$_{0.1}$Al$_{0.4}$ alloy characterized for exhibiting, under bulk conditions, low temperature reentrant spin glass (RSG) behavior and for which experimental and simulation results are available. Our results allow concluding that the variational model is successful in reproducing features of the particle size dependence of the Curie temperature for both pure and random diluted particles. In this last case, low temperature magnetization reduction was consistent with the same type of RSG behavior observed in bulk in accordance with the Almeida-Thouless line at low fields and a linear dependence of the freezing temperature with the reciprocal of the particle diameter was also obtained. Computation of the correlation length critical exponent yielded the values $\nu=0.926\pm 0.004$ via Bogoliubov and$\nu =0.71\pm 0.04$ via Monte Carlo. This fact indicates that even though thermodynamical models can be indeed used in the study of nanostructures and they can reproduce experimental features, special attention must be paid regarding critical behavior. From both approaches, differences in the $\nu$ exponent with respect to the pure Ising model agree with Harris and Fisher arguments.Comment: 11 pages, 11 figures. Submitted to Phys. Rev.

Magnetic properties and critical behavior of random alfa-FeMnAl alloys: An Ising Monte Carlo study

ABSTRACT: The effect of atomic disorder, dilution, and competing interactions upon the magnetic properties of alfa-FeMnAl alloys with different stoichiometries is addressed by means of the Monte Carlo method. Magnetization per site, specific heat, and magnetic susceptibility were computed as a function of temperature on the basis of a Metropolis dynamics, from which critical exponents were estimated. Simulation was carried out in the frame of a random site-diluted three-dimensional Ising model with nearest-neighbor interactions, where Fe-Fe ferromagnetic and Fe-Mn, Mn-Mn antiferromagnetic interactions, as well as the Al dilutor effect, were taken into account. Results, which are summarized in a magnetic phase diagram, reveal the occurrence of several phases including reentrant and pure spin-glass behaviors below around 11 K, and a ferromagnetic to paramagnetic phase transition at temperatures between 100 K and 400 K. Finally, critical exponents, which are consistent with Harris criterion, are also compared to those obtained in other 3D random Ising models

Tailoring dual reversal modes by helicity control in ferromagnetic nanotubes

We investigate the effects of the competition between exchange (J) and dipolar (D) interactions on the magnetization reversal mechanisms of ferromagnetic nanotubes. Using first atomistic Monte Carlo simulations for a model with Heisenberg spins on a cylindrical surface, we compute hysteresis loops for a wide range of the γ=D/J parameter, characterizing the reversal behavior in terms of the cylindrical magnetization components along the tube length. For γ's close to the value for which helical (H) states are energetically favorable at zero applied field, we show that the hysteresis loops can occur in four different classes that are combinations of two reversal modes with well-differentiated coercivities with probabilities that depend on the tube length and radius. This variety in the reversal modes is found to be linked to the metastability of the H states during the reversal that induces different paths followed along the energy landscape as the field is changed. We further demonstrate that reversal by either of the two modes can be induced by tailoring the nanotube initial state so circular states with equal or contrary chirality are formed at the ends, thus achieving low or high coercive fields at will without changing γ. Finally, the results of additional micromagnetic simulations performed on tubes with a similar aspect ratio show that dual switching modes and its tailoring can also be observed in tubes of microscopic dimensions

‘You never know where their hands have been’ – the notion of intellectual disability as contaminated

publishedVersio

Novel routes to metal nanoparticles : electrodeposition and reactions at liquid-liquid interfaces

This thesis considers the nucleation and growth, synthesis, and catalytic application of metallic nanoparticles at liquid|liquid interfaces. It comprises five publications, a previously unpublished synthesis of polymer coated palladium nanoparticles, and an introduction to the relevant literature. Three publications are concerned with electrodeposition of metal nanoparticles at liquid|liquid interfaces. One publication and the results presented here consider the synthesis of silver and palladium colloids by reduction with pyrrole and thiophene monomers. The fifth publication demonstrates the use of gold and palladium colloids as electrocatalysts in two-phase dehalogenation reactions. The literature reviewed serves as an introduction to nanoparticles, liquid|liquid interfaces and electrodeposition studies relevant to the publications and experimental studies presented herein. Nucleation models used are evaluated by numerical means. In the electrodeposition studies, the fundamentals of deposition reactions at liquid|liquid interfaces, involving irreversible Butler-Volmer type growth kinetics and overlap of diffusion fields are developed. The importance of applied potential, particle agglomeration and surface activity on the nucleation process is shown. Small metallic nanoparticles were synthesized in homogeneous media, using novel syntheses involving pyrrole and thiophene derivatives as both reductants and stabilizators. The use of aqueous metal colloids as catalysts for dehalogenation reactions in a two-phase immiscible electrolyte system is demonstrated. Specifically palladium or gold colloids prepared by the citrate reduction method can be negatively charged in a heterogenous two-phase reaction with decamethylferrocene, and subsequently used as an aqueous catalyst for dehalogenation of 2-bromoacetophenone.reviewe

Change in the magnetic configurations of tubular nanostructures by tuning dipolar interactions

We have investigated the equilibrium states of ferromagnetic single wall nanotubes by means of atomistic Monte Carlo simulations of a zig-zag lattice of Heisenberg spins on the surface of a cylinder. The main focus of our study is to determine how the competition between short-range exchange (J) and long-range dipolar (D) interactions influences the low temperature magnetic order of the nanotubes as well as the thermal-driven transitions involved. Apart from the uniform and vortex states occurring for dominant J or D, we find that helical states become stable for a range of intermediate values of γ = D/J that depends on the radius and length of the nanotube. Introducing a vorticity order parameter to better characterize helical and vortex states, we find the pseudo-critical temperatures for the transitions between these states and we establish the magnetic phase diagrams of their stability regions as a function of the nanotube aspect ratio. Comparison of the energy of the states obtained by simulation with those of simpler theoretical structures that interpolate continuously between them, reveals a high degree of metastability of the helical structures that might be relevant for their reversal modes

Rieux (Volvestre)

Date de l'opération : 1990 - 1991 (PR) Inventeur(s) : Johans E À partir d’une prospection entreprise sur le territoire de la commune dans le cadre d’un mémoire de maîtrise portant sur l’occupation du sol à l’époque médiévale, plusieurs édifices cultuels aujourd’hui disparus ont pu être localisés. Ces églises se situent à la Croix de Saint-Ilaire (construction qui date au moins du Xe s.), à Saint-Michel (édifice déjà ruiné en 1690), à Saint-Laurent et Seiglane (mentionnés dans un livre terrier..

Trøblete overganger i et aldersdelt hjelpeapparat

Author's accepted version (postprint)