Theoretical evidence for quasi-molecular structure at small internuclear distances in elastic ion-atom scattering

The potential energy curve of the system Ne-Ne is calculated for small internuclear distances from 0.005 to 3.0 au using a newly developed relativistic molecular Dirac-Fock-Slater code. A significant structure in the potential energy curve is found which leads to a nearly complete agreement with experimental differential elastic scattering cross sections. This demonstrates the presence of quasi-molecular effects in elastic ion-atom collisions at keV energies.

New calculations of P(b) curves for 1s_\sigma excitation in low-Z (Z\le10) ion-atom scattering

Ab initio fully relativistic SCF molecular calculations of energy eigenvalues as well as coupling-matrix elements are used to calculate the 1s_\sigma excitation differential cross section for Ne-Ne and Ne-O in ion-atom collisions. A relativistic perturbation treatment which allows a direct comparison with analogous non-relativistic calculations is also performed.

Theoretical study of the physicochemical properties of the light transactinides

A theoretical study of the physicochemical properties of elements 104, 105, and 106 and their compounds in the gas phase and aqueous solutions has been undertaken using relativistic atomic and molecular codes. Trends in properties such as bonding, ionization potentials, electron affinities, energies of electronic transitions, stabilities of oxidation states etc. have been defined within the corresponding chemical groups and within the transactinides. These trends are shown to be determined by increasing relativistic effects within the groups. The behaviour of some gas phase compounds and complexes in solutions is predicted for the gas chromatography and solvent extraction experiments. Redox potentials in aqueous solutions of these elements are estimated.

Studies in stoichiometry with compositional data

Geochemical data that is derived from the whole or partial analysis of various geologic materials represent a composition of mineralogies or solute species. Minerals are composed of structured relationships between cations and anions which, through atomic and molecular forces, keep the elements bound in specific configurations. The chemical compositions of minerals have specific relationships that are governed by these molecular controls. In the case of olivine, there is a well-defined relationship between Mn-Fe-Mg with Si. Balances between the principal elements defining olivine composition and other significant constituents in the composition (Al, Ti) have been defined, resulting in a near-linear relationship between the logarithmic relative proportion of Si versus (MgMnFe) and Mg versus (MnFe), which is typically described but poorly illustrated in the simplex. The present contribution corresponds to ongoing research, which attempts to relate stoichiometry and geochemical data using compositional geometry. We describe here the approach by which stoichiometric relationships based on mineralogical constraints can be accounted for in the space of simplicial coordinates using olivines as an example. Further examples for other mineral types (plagioclases and more complex minerals such as clays) are needed. Issues that remain to be dealt with include the reduction of a bulk chemical composition of a rock comprised of several minerals from which appropriate balances can be used to describe the composition in a realistic mineralogical framework. The overall objective of our research is to answer the question: In the cases where the mineralogy is unknown, are there suitable proxies that can be substituted? Kew words: Aitchison geometry, balances, mineral composition, oxides

Análisis de los factores políticos y sociales que inciden en una reforma agraria en Colombia. Estudio de caso: Reforma de 1961

La concentración de tierras ha sido una problemática recurrente en la historia de Colombia. La desigualdad en la distribución de las tierras ha moldeado constantemente a lo largo de las décadas nuestra realidad nacional. A pesar de la implementación de políticas agrarias en el pasado como la ley 200 de 1936 y la ley 135 de 1961, el conflicto agrario ha afectado de manera constante como generador de inequidad, violencia y desplazamiento dentro de la sociedad colombiana desde la Independencia hasta nuestros días, sin que hasta el momento el problema sobre la tenencia de la tierra haya sido resuelto.

Estrategias para el funcionamiento integral de los servicios de salud para la comunidad indígena Nükak del Guaviare

Los Nükák son un pueblo indígena nómada del nordeste amazónico, ubicados en el departamento del Guaviare que basa su supervivencia en prácticas de caza y recolección principalmente. Desde su contacto con la sociedad mayoritaria, esta población se ha encontrado amenazada en su pervivencia como pueblo, en especial por las características de la población de colonos que ingresó a su territorio, el conflicto armado que los impacta provocando muertes y desplazamientos, y un nuevo departamento como lo es el Guaviare (1991) con grandes dificultades sociales, políticas y económicas; siendo la salud de los Nükák una de las más afectadas en medio de este complejo contexto. Ante esta necesidad, se hace imperativo generar una estrategia para el funcionamiento integral de los servicios de salud específica para esta comunidad, que reconozca por un lado la realidad local y su influencia en el citado pueblo y por otro, la percepción que tiene dicho pueblo sobre su salud, analizando el contexto de los Nükák a partir de un estado del arte y su sentir a partir de encuestas aplicadas a mujeres casadas de dicho pueblo. Este estudio es una expresión novedosa e intercultural de la Atención primaria desde la promoción de la salud y prevención de la enfermedad, de la operatividad del primer y segundo nivel de atención, del diagnóstico, la rehabilitación, las redes integradas e integrales, la participación, la intersectorialidad, entre otros elementos adaptados a la cultura Nükák que articulados son la estrategia para el funcionamiento integral del servicio de salud para el pueblo Nükák de San José del Guaviare.

La necesidad de establecer una condición jurídica para quienes deben migrar por causa de los desastres naturales : una realidad que atender desde la perspectiva de los derechos humanos

El incremento desmedido en el número de desastres naturales, sumado a la frecuencia con que estos ocurren a lo largo del mundo entero, ha evidenciado una de las mayores preocupaciones de los Estados: el desplazamiento forzado de la población por esta causa y la delicada situación de derechos humanos que esto implica, por lo cual los Organismos Internacionales han instado en reiteradas oportunidades a los Estados para actuar conjunta y prontamente para evitar que esta siga siendo una de las causas más altas de desplazamiento. Esta migración forzada pone de presente una problemática al no existir una posición universalmente aceptada sobre cuál es la condición jurídica de las personas que, por causa de los desastres naturales, deben dejarlo todo; la ausencia de esta categorización conlleva a la inexistencia de un marco legal internacional aplicable y con ello, a un vacío en la regulación interna de los Estados. Esta investigación pretende analizar los conceptos de migración existentes en el derecho internacional y establecer si la condición jurídica de quienes deben dejarlo todo por causa de los desastres naturales encaja dentro de alguna de estas categorías o si se hace necesario crear una nueva categoría que atienda las particularidades del contexto de este fenómeno migratorio, desde una perspectiva de derechos humanos. Para esto, se realizan reflexiones sobre tales conceptos así como un análisis de algunos casos de referencia, incluyendo la situación vivida en Colombia con la Ola Invernal de 2010, buscando realizar algunas propuestas de posibles soluciones jurídicamente viables.

Sexual Violence Beyond all Reasonable Doubt

Establishing the pattern of crime is fundamental for the successful investigation ofinternational crimes (genocide, war crimes, and crimes against humanity). A patternof crime is the aggregate of multiple incidents that share common features related tothe victims, the perpetrators, and the modus operandi. Pattern evidence and analysishave been used successfully, mainly in the investigation of large-scale killings, destruction,and displacement; the use for sexual violence charges has been remarkablymore limited. There is a need to overcome this gap by setting proper methods of datacollection and analysis. At the level of evidence collection, under-reporting should beaddressed through victimization surveys or secondary analysis of data available fromdifferent sources. At the level of analysis, the available evidence needs to be subject toimpartial examination beyond the pre-conceptions of the conflict parties and advocacygroups, in compliance with scientific standards for quantitative, qualitative, andGIS (Geographic Information Systems)methods. Reviewing the different investigativeexperiences and jurisprudence will help to set the right methodology and contribute mostefficiently to putting an end to the impunity regarding sexual crimes.

Oportunidades de participación laboral en la localidad de bosa para jóvenes entre los 18 y 24 años desplazados por el conflicto armado, una revisión documental

Se realiza una revisión documental sobre la problemática del conflicto armado y el fenómeno de desplazamiento, específicamente en la Localidad de Bosa, ya que es una de las que más recibe población desplazada de otras regiones del País. Se realiza la revisión documental en bases de datos como Ebsco, Proquest y Scopus, incluyendo combinaciones tales como: "Occupational Therapy" and "youth" and "Forced displacement" or "refugees" and "employment inclusion". Se espera determinar los programas de vinculación y formación laboral de jóvenes en situación de desplazamiento. Se encuentra que esta población aún carece de apoyo por parte de instancias gubernamentales y de perfiles ocupacionales que encaminen los intereses y habilidades de esta población hacia el desempeño de roles productivos y educativos propios de su condición de jóvenes.

Electron localization function at the correlated level

The electron localization function (ELF) has been proven so far a valuable tool to determine the location of electron pairs. Because of that, the ELF has been widely used to understand the nature of the chemical bonding and to discuss the mechanism of chemical reactions. Up to now, most applications of the ELF have been performed with monodeterminantal methods and only few attempts to calculate this function for correlated wave functions have been carried out. Here, a formulation of ELF valid for mono- and multiconfigurational wave functions is given and compared with previous recently reported approaches. The method described does not require the use of the homogeneous electron gas to define the ELF, at variance with the ELF definition given by Becke. The effect of the electron correlation in the ELF, introduced by means of configuration interaction with singles and doubles calculations, is discussed in the light of the results derived from a set of atomic and molecular systems

Slicing of soft, flexible solids with industrial applications

Thin slices of soft flexible solids have negligible bending resistance and hence store negligible elastic strain energy; furthermore such offcuts are rarely permanently deformed after slicing. Cutting forces thus depend only on work of separation (toughness work) and friction. These simplifying assumptions are not as restrictive as it might seem, and the mechanics are found to apply to a wide variety of foodstuffs and biological materials. The fracture toughness of such materials may be determined from cutting experiments: the use of scissors instrumented for load and displacement is a popular method where toughness is obtained from the work areas beneath load–displacement plots. Surprisingly, there is no analysis for the variation of forces with scissor blade opening and this paper provides the theory. Comparison is made with experimental results in cutting with scissors. The analysis is generalised to cutting with blades of variable curvature and applied to a commercial food cutting device having a rotating spiral plan form blade. The strong influence of the ‘slice/push ratio’ (blade tangential speed to blade edge normal speed) on the cutting forces is revealed. Small cutting forces are important in food cutting machinery as damage to slices is minimised. How high slice/push ratios may be achieved by choice of blade profile is discussed.

The Nutritional Significance of Lipid Rafts

The structure, size, stability, and functionality of lipid rafts are still in debate, but recent techniques allowing direct visualization have characterized them in a wide range of cell types. Lipid rafts are potentially modifiable by diet, particularly (but not exclusively) by dietary fatty acids. However, it is not clear whether dietary polyunsaturated fatty acids (PUFAs) are incorporated into raft lipids or whether their low affinity to cholesterol disallows this and causes phase separation from rafts and displacement of raft proteins. This review examines the potential for dietary modification of raft structure and function in the immune system, brain and retinal tissue, the gut, and in cancer cells. Although there is increasing evidence to suggest that membrane microdomains, and their modulation, have an impact in health and disease, it is too early to judge whether modulation of lipid rafts is responsible for the immunomodulatory effects of n-3 PUFA. In addition to dietary fatty acids, gangliosides and cholesterol may also modulate microdomains in a number of tissues, and recent work has highlighted sphingolipids in membrane microdomains as potential targets for inhibition of tumor growth by n-3 PUFA. The roles of fatty acids and gangliosides in cognitive development, age-related cognitive decline, psychiatric disorders, and Alzheimer's disease are poorly understood and require clarification, particularly with respect to the contribution of lipid rafts. The roles of lipid rafts in cancer, in microbial pathogenesis, and in insulin resistance are only just emerging, but compelling evidence indicates the growing importance of membrane microdomains in health and disease.

Symmetry controlled spin polarized conductance in Au nanowires

The fact that the resistance of propagating electrons in solids depends on their spin orientation has led to a new field called spintronics. With the parallel advances in nanoscience, it is now possible to talk about nanospintronics. Many works have focused on the study of charge transport along nanosystems, such as carbon nanotubes, graphene nanoribbons, or metallic nanowires, and spin dependent transport properties at this scale may lead to new behaviors due to the manipulation of a small number of spins. Metal nanowires have been studied as electric contacts where atomic and molecular insertions can be constructed. Here we describe what might be considered the ultimate spin device, namely, a Au thin nanowire with one Co atom bridging its two sides. We show that this system has strong spin dependent transport properties and that its local symmetry can dramatically change them, leading to a significant spin polarized conductance.

Single-mode acceleration of matter waves in circular waveguides

Ultracold gases in ring geometries hold promise for significant improvements of gyroscopic sensitivity. Recent experiments have realized atomic and molecular storage rings with radii in the centimeter range, sizes whose practical use in inertial sensors requires velocities significantly in excess of typical recoil velocities. We use a combination of analytical and numerical techniques to study the coherent acceleration of matter waves in circular waveguides, with particular emphasis on its impact on single-mode propagation. In the simplest case we find that single-mode propagation is best maintained by the application of time-dependent acceleration force with the temporal profile of a Blackmann pulse. We also assess the impact of classical noise on the acceleration process.