1,457 research outputs found
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
ODA in Galicia (Spain). The importance of the fisheries sector and the cultural priority
This article analyses the motivations, priorities and financing of Galician Official Development Aid (ODA) in relation to Spanish ODA. We will focus mainly on the Portuguese-speaking African countries (PALOP), paying special attention to the cases of Cape Verde and Mozambique, both priorities for the Galician cooperation programs, due to their linguistic proximity and the fact that fishing takes on a significant role. To understand the orientations of Galician ODA, it is important to consider three priorities, geographical, sectoral and cultural.
Fishing is relevant in any of these priorities, as a strategic sector for the economy of Galicia and Portuguesespeaking countries due to the linguistic proximity between Galician and Portuguese. Therefore, there is a willingness to project regional interests in foreign actions, although always coordinated along the main Spanish and European cooperation lines. However, the decentralised policy of Galician cooperation, characterised in economic terms by its weakness, has encountered certain difficulties in developing its strategies. The main
difficulty lies in the small size of Galician Non-governmental development organisations (NGDOs), which are unable to manage large projects, while bigger NGDOs manage a large part of the cooperation funds, with national or international interests that do not always coincide with the interests of Galicia. In this article we will show that, despite these drawbacks, the fishing orientation of ODA in Galicia is still relevant, and cooperation
with Portuguese-speaking countries is also unique in the Spanish context. However, it is necessary to strengthen a regional vision that can generate more benefits for both the donor region and the receiving country, as well as helping the local population to better understand the meaning and benefits generated by ODA.S
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
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