Sputniks cubanos. De cómo la URSS ocupó la imaginación de una generación

Resumen: A pesar de la cierta marginalidad de la ciencia ficción en Cuba, ésta no estuvo exenta de la influencia cultural que sufrió la isla al sovietizarse. De la URSS y el entorno comunista llegaron cientos de obras del género, al mismo tiempo que la producción local se reducía a cero en los años setenta. Los autores cubanos tomaron partido, unos defendieron los nuevos estilos e ideas venidos del Este; otros decidieron seguir su camino, algunas veces, a contracorriente.  Despite the somewhat marginalization of science fiction in Cuba, the genre could not avoid the cultural influence that the island experienced when it adopted Soviet cannons. From the USSR and the Communist allies came hundreds of genre publications in the seventies, while local production was reduced to zero. Most Cuban writers took sides, some defended the new styles and ideas that came from the East; others decided not to, and even created sometimes a counter discourse

Independent ferroelectric contributions and rare-earth-induced polarization reversal in multiferroic TbMn2O5

Three independent contributions to the magnetically induced spontaneous polarization of multiferroic TbMn2O5 are uniquely separated by optical second harmonic generation and an analysis in terms of Landau theory. Two of them are related to the magnetic Mn3+/4+ order and are independent of applied fields of up to 7 T. The third contribution is related to the long-range antiferromagnetic Tb3+ order. It shows a drastic decrease upon the application of a magnetic field and mediates the change of sign of the spontaneous electric polarization in TbMn2O5. The close relationship between the rare-earth long-range order and the non-linear optical properties points to isotropic Tb-Tb exchange and oxygen spin polarization as mechanism for this rare-earth induced ferroelectricity.Comment: 8 pages, 5 figure

Diversity of N2-fixing cyanobacteria from Andalusian paddy fields and analysis of their potential as bioinoculants

The marshes of the Guadalquivir River contain the largest area of rice cultivation in Spain, where more than 40,000 ha are used every year for rice production. These wetland areas provide a perfect place for rice cultivation, and represent a unique aquaticterrestrial habitat that hold more wintering waterfowl than any other European wetland. Paddies require large amounts nitrogen and phosphorus for their growth, development and production. Though, flooded conditions used for rice cultivation drastically diminish efficiency inorganic nitrogen fertilizers, being only 30–40% used by the plant, and in some cases even less. Large amounts of nitrogen fertilizers are dissolved in the surface water and lost, causing environmental pollution and health problems due to losses through N2O and NO volatilization, denitrification, and leaching (Ishii et al., 2011)

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

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

Microtensile bond strength of several adhesive systems to different dentin depths

Abstract no. 15published_or_final_versio

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

‘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

Observation of a continuous phase transition in a shape-memory alloy

Elastic neutron-scattering, inelastic x-ray scattering, specific-heat, and pressure-dependent electrical transport measurements have been made on single crystals of AuZn and Au_{0.52}Zn_{0.48} above and below their martensitic transition temperatures (T_M=64K and 45K, respectively). In each composition, elastic neutron scattering detects new commensurate Bragg peaks (modulation) appearing at Q = (1.33,0.67,0) at temperatures corresponding to each sample's T_M. Although the new Bragg peaks appear in a discontinuous manner in the Au_{0.52}Zn_{0.48} sample, they appear in a continuous manner in AuZn. Surprising us, the temperature dependence of the AuZn Bragg peak intensity and the specific-heat jump near the transition temperature are in favorable accord with a mean-field approximation. A Landau-theory-based fit to the pressure dependence of the transition temperature suggests the presence of a critical endpoint in the AuZn phase diagram located at T_M*=2.7K and p*=3.1GPa, with a quantum saturation temperature \theta_s=48.3 +/- 3.7K.Comment: 6 figure