Pretransitional phenomena in dilute crystals with first-order phase transition

Pretransitional phenomena at first-order phase transition in crystals diluted by 'neutral' impurities (analogue of nonmagnetic atoms in dilute magnets) are considered. It is shown that field dependence of order parameter becomes nonanalytical in the stability region of the ordered phase, while smeared jumps of thermodynamic parameters and anomalous (non-exponential) relaxation appear near transition temperature of pure crystal.Comment: 4 page

Tipología de productores de durazno en Zacatecas, México por atributos de calidad del fruto

Zacatecas se posiciona entre los cinco principales Estados productores de durazno en México. El durazno es criollo, amarillo, hueso pegado, pulpa firme, propagado sexualmente y cultivado en temporal en ˜ 81% de la superficie cultivada; lo que, destaca la baja competitividad de este cultivo. No obstante, por el número de productores dedicados a este cultivo, realza su importancia socioeconómica con relación a otros frutales. Si se pretende entender las características y problemáticas de las unidades de producción (UP) que sirvan como un instrumento para optimizar la asignación de recursos públicos, y proponer estrategias que mejoren el desarrollo de la agricultura, es necesario entender la heterogeneidad de los productores considerando sus características socioeconómicas dentro de las UP. Por ello, en esta investigación se buscó analizar y segmentar técnica y tipológicamente a los productores de durazno del estado de Zacatecas. Los datos se recopilaron a través de una encuesta a 204 productores de durazno en Zacatecas, México. Los resultados sugieren cuatro tipos de productores: 1) aquellos que plantan durazno sin objetivo; 2) los que plantan durazno a nivel de traspatio; 3) productores donde el durazno forma parte de un sistema de producción agropecuario; y 4) productores empresarios de durazno. En esta última categoría, se encontró ˜31% de los productores, lo cual podría explicar, en parte, la baja competitividad del cultivo ante otros sistemas productoPeer ReviewedPostprint (published version

Finite strain Landau theory of high pressure phase transformations

The properties of materials near structural phase transitions are often successfully described in the framework of Landau theory. While the focus is usually on phase transitions, which are induced by temperature changes approaching a critical temperature T-c, here we will discuss structural phase transformations driven by high hydrostatic pressure, as they are of major importance for understanding processes in the interior of the earth. Since at very high pressures the deformations of a material are generally very large, one needs to apply a fully nonlinear description taking physical as well as geometrical nonlinearities (finite strains) into account. In particular it is necessary to retune conventional Landau theory to describe such phase transitions. In Troster et al (2002 Phys. Rev. Lett. 88 55503) we constructed a Landau-type free energy based on an order parameter part, an order parameter-(finite) strain coupling and a nonlinear elastic term. This model provides an excellent and efficient framework for the systematic study of phase transformations for a wide range of materials up to ultrahigh pressures

Ground state representations of loop algebras

Let g be a simple Lie algebra, Lg be the loop algebra of g. Fixing a point in S^1 and identifying the real line with the punctured circle, we consider the subalgebra Sg of Lg of rapidly decreasing elements on R. We classify the translation-invariant 2-cocycles on Sg. We show that the ground state representation of Sg is unique for each cocycle. These ground states correspond precisely to the vacuum representations of Lg.Comment: 22 pages, no figur

Landau Theory of Domain Wall Magnetoelectricity

We calculate the exact analytical solution to the domain wall properties in a multiferroic system with two order parameters that are coupled bi-quadratically. This is then adapted to the case of a magnetoelectric multiferroic material such as BiFeO3, with a view to examine critically whether the domain walls can account for the enhancement of magnetization reported for thin films fo this material, in view of the correlation between increasing magnetization and increasing volume fraction of domain walls as films become thinner. The present analysis can be generalized to describe a class of magnetoelectric devices based upon domain walls rather than bulk properties.Comment: 9 pages, 4 figure

Gobernanza y lucha contra la pobreza

[spa] El presente trabajo trata de analizar las políticas contra la pobreza aplicadas por España en el marco de la estrategia Europa 2020. Estas políticas se han llevado a cabo mediante mecanismos de gobernanza -en concreto, el denominado experimentalismo democrático-, cuya efectividad y legitimidad están en entredicho. Para ello se analizará, de un lado, el Semestre Europeo, que coordina estas políticas a nivel de la UE. Del otro, distintos documentos españoles que se enmarcan en este proceso y que permiten evaluar los niveles de legitimidad democrática de este mecanismo. This paper attempts to analyze policies against poverty undertaken by Spain within the framework of the Europe 2020 strategy. These policies have been applied through mechanisms of governance mechanisms -specifically, the so-called democratic experimentalism- whose effectiveness and legitimacy is at least questionable. To this end, this paper tries to analyze, on one side, the European Semester, which coordinates these policies at an EU level. On the other, various Spanish documents that are part of this process and therefore allow us assess the levels of democratic effectiveness of this mechanism.[eng] This paper attempts to analyze policies against poverty undertaken by Spain within the framework of the Europe 2020 strategy. These policies have been applied through mechanisms of governance mechanisms -specifically, the so-called democratic experimentalism- whose effectiveness and legitimacy is at least questionable. To this end, this paper tries to analyze, on one side, the European Semester, which coordinates these policies at an EU level. On the other, various Spanish documents that are part of this process and therefore allow us assess the levels of democratic effectiveness of this mechanism

‘If you look the part you’ll get the job’: should career professionals help clients to enhance their career image?

This article presents a critical exploration of the role of career professionals in supporting people to reflect on and enhance their appearance, attractiveness and self-presentation (career image). The article is conceptual and based on a review of the broader literature on career success, appearance and attractiveness. It explores the evidence for a relationship between attractiveness and career, and the authors propose a conceptual framework in which career image is comprised of three elements (interpersonal skills, aesthetic presentation and beauty). The paper examines a possible role for career professionals in relation to this and then critically examines this role and concludes with the proposition of a research agenda in this area

Limits of Gaudin algebras, quantization of bending flows, Jucys--Murphy elements and Gelfand--Tsetlin bases

Gaudin algebras form a family of maximal commutative subalgebras in the tensor product of $n$ copies of the universal enveloping algebra U(\g) of a semisimple Lie algebra \g. This family is parameterized by collections of pairwise distinct complex numbers $z_1,...,z_n$. We obtain some new commutative subalgebras in U(\g)^{\otimes n} as limit cases of Gaudin subalgebras. These commutative subalgebras turn to be related to the hamiltonians of bending flows and to the Gelfand--Tsetlin bases. We use this to prove the simplicity of spectrum in the Gaudin model for some new cases.Comment: 11 pages, references adde

The X-ray binary 2S0114+650=LSI+65 010:A slow pulsar or tidally-induced pulsations?

The X-ray source 2S0114+650=LSI+65 010 is a binary system containing a B-type primary and a low mass companion believed to be a neutron star. The system has three reported periodicities: the orbital period, P{orb}~11.6 d, X-ray flaring with P{flare}~2.7 hr, and a "superorbital" X-ray periodicity P{super}~30.7 d. The objective of this paper is to show that the puzzling periodicities in the system may be explained in the context of scenarios in which tidal interactions drive oscillations in the B-supergiant star. We calculate the solution of the equations of motion for one layer of small surface elements distributed along the equator of the star, as they respond to the forces due to gas pressure, centrifugal, coriolis, viscous forces, and the gravitational forces of both stars. This calculation provides variability timescales that can be compared with the observations. In addition, we use observational data obtained at the Observatorio Astron\'omico Nacional en San Pedro M\'artir (OAN/SPM) between 1993-2004 to determine which of the periodicities may be present in the optical region. We suggest that the tidal oscillations lead to a structured stellar wind which, when fed to the neutron star, produces the X-ray modulations. The connection between the stellar oscillations and the modulation of the mass ejection may lie in the shear energy dissipation generated by the tangential motions that are produced by the tidal interaction, particularly in the tidal bulge region. The tidal oscillation scenario weakens the case for 2S0114+650 containing a magnetar descendent.Comment: 12 pages, 14 figure