Phonon dispersion curves and atomic mean square displacement for several fcc and bcc materials

The atomic mean square displacement (MSD) and the phonon dispersion curves (PDC's) of a number of face-centred cubic (fcc) and body-centred cubic (bcc) materials have been calclllated from the quasiharmonic (QH) theory, the lowest order (A2 ) perturbation theory (PT) and a recently proposed Green's function (GF) method by Shukla and Hiibschle. The latter method includes certain anharmonic effects to all orders of anharmonicity. In order to determine the effect of the range of the interatomic interaction upon the anharmonic contributions to the MSD we have carried out our calculations for a Lennard-Jones (L-J) solid in the nearest-neighbour (NN) and next-nearest neighbour (NNN) approximations. These results can be presented in dimensionless units but if the NN and NNN results are to be compared with each other they must be converted to that of a real solid. When this is done for Xe, the QH MSD for the NN and NNN approximations are found to differ from each other by about 2%. For the A2 and GF results this difference amounts to 8% and 7% respectively. For the NN case we have also compared our PT results, which have been calculated exactly, with PT results calculated using a frequency-shift approximation. We conclude that this frequency-shift approximation is a poor approximation. We have calculated the MSD of five alkali metals, five bcc transition metals and seven fcc transition metals. The model potentials we have used include the Morse, modified Morse, and Rydberg potentials. In general the results obtained from the Green's function method are in the best agreement with experiment. However, this improvement is mostly qualitative and the values of MSD calculated from the Green's function method are not in much better agreement with the experimental data than those calculated from the QH theory. We have calculated the phonon dispersion curves (PDC's) of Na and Cu, using the 4 parameter modified Morse potential. In the case of Na, our results for the PDC's are in poor agreement with experiment. In the case of eu, the agreement between the tlleory and experiment is much better and in addition the results for the PDC's calclliated from the GF method are in better agreement with experiment that those obtained from the QH theory.

Identidty, displacement and embodiment in women's independent cinema

Ma thèse examine les déplacements multiples – déportation, exil, voyage – et l‟expérience diasporique de différentes communautés ethniques dans le cinéma indépendant de trois réalisatrices et artistes contemporaines : Julie Dash, Rea Tajiri et Trinh T. Minh-ha. J‟analyse la déconstruction et reconstruction de l‟identité à travers le voyage et autres déplacements physiques ainsi que les moyens d‟expression et stratégies cinématographiques utilisées par ces artistes pour articuler des configurations identitaires mouvantes. Je propose de nouvelles lectures de la position des femmes dans des milieux culturels différents en considérant la danse comme une métaphore de la reconfiguration de l‟identité féminine qui se différencie et s‟émancipe des traditions culturelles classiques. Les expériences de l‟histoire et de la mémoire, qui sont vécues dans les corps des femmes, sont aussi exprimées par le biais des relations intermédiales entre la photographie, la vidéo et le film qui proposent des images de femmes variées et complexes.

Hysteresis in a system driven by either generalized force or displacement variables: martensitic phase transition in single-crystalline Cu-Zn-Al

We report on experiments aimed at comparing the hysteretic response of a Cu-Zn-Al single crystal undergoing a martensitic transition under strain-driven and stress-driven conditions. Strain-driven experiments were performed using a conventional tensile machine while a special device was designed to perform stress-driven experiments. Significant differences in the hysteresis loops were found. The strain-driven curves show reentrant behavior yield point which is not observed in the stress-driven case. The dissipated energy in the stress-driven curves is larger than in the strain-driven ones. Results from recently proposed models qualitatively agree with experiments.

Internal Displacement, the Guiding Principles on Internal Displacement, the Principles Normative Status, and the Need for their Effective Domestic Implementation in Colombia.

El artículo analiza el fenómeno del desplazamiento forzado alrededor del mundo, así como la génesis del mandato de las Naciones Unidas para luchar contra este problema. Examina las conclusiones clave del estudio de la ONU que encontró que las normas existentes del derecho internacional tienen varios vacíos y zonas grises relativos a las necesidades de los desplazados internos. También analiza los orígenes y el contenido de los principios guía del desplazamiento interno, así como el estatus normativo de los mismos. Así mismo, sugiere que, a pesar de no ser vinculante para los Estados, estos principios guía se convirtieron en la expresión más autorizada de los estándares mínimos aplicables a los desplazados internos como consecuencia de la práctica estatal, es decir, que la mayoría de estos principios se volverán costumbre internacional. El artículo también señala la necesidad de que haya una implementación efectiva en el derecho interno de estos principios guía; examina cómo las autoridades gubernamentales, la Corte Constitucional y la sociedad civil en Colombia, así como las entidades intergubernamentales, respondieron a la crisis del desplazamiento interno en el país. Observando el marco legal colombiano en desplazamiento interno, el artículo concluye que el Estado no ha tomado las medidas necesarias requeridas para prevenir futuros desplazamientos o para asegurar una protección y asistencia efectivas para resolver las necesidades de los desplazados internos.

Land Restitution and Prevention of Forced Displacement in Colombia

The armed conflict in Colombia, which has generated over three million internally displaced persons, has dramatic humanitarian consequences and raises serious issues regarding the protection of displaced peoples’ rights. The underlying reasons for the displacement often lie in the dynamics associated with territorial control and land seizures undertaken for strategic, military or purely economic purposes. Domestic and international legal provisions have established the victims’ right to the restitution of their homes and property as the “preferred remedy” in cases of displacement. However, policies dealing with displacement, both those of the Colombian government and of several international institutions, fail to take this sufficiently into account. A comprehensive reparation policy for victims must necessarily entail the reversion of lands, territories and goods seized in Colombia under the pretext of the internal armed conflict.

A Grey Area of Rights and Knowledge: Displacement in Colombia, South-South Migration and Health Equity

Globalization and liberalization of the economies have produced among others drastic effects on the human mobility, generating confusion, enhancing discrimination and a lack of respect to the rights of several migrant collectives. In this article we analyse several challenges for the study of these phenomena, based on the case of the neglected health rights of Colombian women, who have been forced to displace by the country's internal conflict, and are thus pushed to cross the border to Ecuador. The article identifies several knowledge gaps that could allow and advance a better understanding of these critical subjects. The paper - a think piece -is based upon a general review of documents and studies on the relation between migration and health. The supporting theory on the research comes from international organisations such as the WHO and IOM, NGOs, grass-roots organisations and academic research. This paper shows the need for focusing on the reality of supra states which globalization has generated, and t e urgency of securing the access to essential health preconditions to migrant populations. These issues can no longer be neglected and should be included on agendas at international level, widening the approach of programs to the displaced/immigrant population by taking into account the need to ensure the essential health preconditions (equity), prevention, and protection. Further, it is clear that women and children require a better protection with enhanced prevention and responding measures to sexual abuse, stigmatisation, violence and the respect of their rights.

Displacement of Zn through acidic light-textured soils

In order to gain understanding of the movement of pollutant metals in soil. the chemical mechanisms involved in the transport of zinc were studied. The displacement of zinc through mixtures of sand and cation exchange resin was measured to validate the methods used for soil. With cation exchange capacities of 2.5 and 5.0 cmol(c) kg(-1). 5.6 and 8.4 pore volumes of 10 mM CaCl2, respectively, were required to displace a pulse of ZnCl2. A simple Burns-type model (Wineglass) using an adsorption coefficient (K-d) determined by fitting a straight line relationship to an adsorption isotherm gave a good fit to the data (K-d=0.73 and 1.29 ml g(-1), respectively). Surface and subsurface samples of an acidic sandy loam (organic matter 4.7 and 1.0%. cation exchange capacity (CEC) 11.8 and 6.1 cmol(c) kg(-1) respectively) were leached with 10 mM calcium chloride. nitrate and perchlorate. With chloride. the zinc pulse was displaced after 25 and 5 pore volumes, respectively. The Kd values were 6.1 and 2.0 ml g(-1). but are based on linear relationships fitted to isotherms which are both curved and show hysteresis. Thus. a simple model has limited value although it does give a general indication of rate of displacement. Leaching with chloride and perchlorate gave similar displacement and Kd values, but slower movement occurred with nitrate in both soil samples (35 and 7 pore volumes, respectively) which reflected higher Kd values when the isotherms were measured using this anion (7.7 and 2.8 ml g(-1) respectively). Although pH values were a little hi-her with nitrate in the leachates, the differences were insufficient to suggest that this increased the CEC enough to cause the delay. No increases in pH occurred with nitrate in the isotherm experiments. Geochem was used to calculate the proportions of Zn complexed with the three anions and with fulvic acid determined from measurements of dissolved organic matter. In all cases, more than 91% of the Zn was present as Zn2+ and there were only minor differences between the anions. Thus, there is an unexplained factor associated with the greater adsorption of Zn in the presence of nitrate. Because as little as five pore volumes of solution displaced Zn through the subsurface soil, contamination of ground waters may be a hazard where Zn is entering a light-textured soil, particularly where soil salinity is increased. Reductions in organic matter content due to cultivation will increase the hazard. (C) 2004 Elsevier B.V. All rights reserved.

Theoretical and experimental investigation of wall confluent jets ventilation and comparison with wall displacement ventilation

This paper reports CFD and experimental results of the characteristics of wall confluent jets in a room. The results presented show the behaviour of wall confluent jets in the form of velocity profiles, the spreading rate of jets on the surface, jets decay, etc. The empirical equations derived are compared with other types of air jets. In addition, the flow in wall confluent jets is compared with the flow in displacement ventilation supply, with regards to the vertical and horizontal spreading on the floor. It is concluded that the jet momentum of wall confluent jets can be more conserved than other jets. Thus, wall confluent jets have a greater spread over the floor than displacement flow.

Measuring toughness and the cohesive stress-displacement relationship by the essential work of fracture concept

The complete fracture behaviour of ductile double edge notched tension (DENT) specimen is analysed with an approximate model, which is then used to discuss the essential work of fracture (EWF) concept. The model results are compared with the experimental results for an aluminium alloy 6082-O. The restrictions on the ligament size for valid application of the EWF method are discussed with the aid of the model. The model is used to suggest an improved method of obtaining the cohesive stress-displacement relationship for the fracture process zone (FPZ).