Nonequilibrium dynamics of spin-boson models from phase space methods

An accurate description of the nonequilibrium dynamics of systems with coupled spin and bosonic degrees of freedom remains theoretically challenging, especially for large system sizes and in higher than one dimension. Phase space methods such as the Truncated Wigner Approximation (TWA) have the advantage of being easily scalable and applicable to arbitrary dimensions. In this work we adapt the TWA to generic spin-boson models by making use of recently developed algorithms for discrete phase spaces [Schachenmayer, PRX 5, 011022 (2015)]. Furthermore we go beyond the standard TWA approximation by applying a scheme based on the Bogoliubov-Born-Green-Kirkwood-Yvon (BBGKY) hierarchy of equations [Pucci, PRB 93, 174302 (2016)] to our coupled spin-boson model. This allows in principle to study how systematically adding higher order corrections improves the convergence of the method. To test various levels of approximation we study an exactly solvable spin-boson model which is particularly relevant for trapped-ion arrays. Using TWA and its BBGKY extension we accurately reproduce the time evolution of a number of one- and two-point correlation functions in several dimensions and for arbitrary number of bosonic modes.Comment: 10+5 pages, 5 figure

Sobre condiciones de integrabilidad de una estructura j satisfaciendo (j2-p2) (j2 +q2 ) = 0

We consider the structures defined by a tensor field J of type (1,1) which satisfy the condition (J2-p2)(J2+q2)=0 characterizing its integrability in term of its Nijenhuis tenso

Aplicaciones y limitaciones del coeficiente K de eficacia de la adición de escoria de horno alto en el hormigón

Recently, a k-value for ground granulated blast-furnace slag or k-value has been added to the revision of the European standard EN 206-1:2000. The proposed values during the disscusion in the working groups were very different because in most of cases the compressive strength was the only characteristic considered; while only in few cases the concrete durability was taken into account when ground granulated blast-furnace slag is added directly to the mix. Advantages and disadvantages of the k-values found in the literature are discussed in this paper. The final conclusion may be summarised suggesting a logical proposal of addressing to each country the choice of the k-value in function of the concrete application, environment and placing conditions selected according to their own experience.Recientemente se ha incorporado un valor del coeficiente de eficacia K para la escoria de horno alto en la norma europea EN 206-1:2000. Los valores propuestos en los grupos de trabajo eran muy diversos ya que en algunos casos sólo consideraban la resistencia mecánica para su determinación mientras que en otros se remarcaba la importancia de tener en cuenta, además, aspectos relativos a la durabilidad del hormigón con dicha adición. En el presente artículo se discuten las ventajas y desventajas de proponer unos valores del coeficiente de eficacia K más o menos conservadores. La conclusión final se resume con la propuesta de una recomendación lógica que consiste en trasladar a cada país la elección del coeficiente K para que pueda aplicarse a los hormigones empleados en su territorio; tales valores de K deberán ser seleccionados de acuerdo con la experiencia de cada uno de los países

Los estudios de Grado en la formación inicial de Maestros en Educación Primaria. Miradas de formadores y de futuros maestros.

Presentamos a los lectores de la Revista Profesorado un Monográfico sobre el desarrollo del conocimiento profesional en la formación inicial de Maestros en Educación Primaria. Es fruto de la realización de un Proyecto de Investigación Coordinado entre las universidades de Santiago de Compostela (USC) y Barcelon (UB), financiado por el Ministerio de Economía y Competitividad (MINECO)1 y realizado en el periodo 2013-201

Dithiothreitol increases f3-glucuronidase accumulation in transformed tobacco (Nicotiana tabacum) protoplasts without altering their viability or the synthesis and export of cellular proteins

The effect of dithiothreitol (DTT) on the expression of the β-glucuronidase (GUS) reporter gene under the control of the CaMV-35 S promoter has been investigated by radioactive labelling and immunoprecipitation of the enzyme in protoplasts from stably transformed tobacco plants and compared with that observed in protoplasts transiently expressing the same gene construct. An increase in net accumulation of GUS during the culture period in response to externally added DTT (2 mm) was observed both in protoplasts from transformed tobacco plants and in electroporated protoplasts. DTT had no effect on rate of degradation of the mature GUS protein, as shown in a pulse-chase experiment. Relevant aspects of protoplast physiology, such as viability, synthesis of 35S-labelled cellular proteins, or synthesis and export of pathogenesis-related proteins (one putative chitinase and two 1,3-β-glucanases) were not affected by the reducing reagen