Composite Boson Mapping for Lattice Boson Systems

We present a canonical mapping transforming physical boson operators into quadratic products of cluster composite bosons that preserves matrix elements of operators when a physical constraint is enforced. We map the 2D lattice Bose-Hubbard Hamiltonian into $2\times 2$ composite bosons and solve it at mean field. The resulting Mott insulator-superfluid phase diagram reproduces well Quantum Monte Carlo results. The Higgs boson behavior along the particle-hole symmetry line is unraveled and in remarkable agreement with experiment. Results for the properties of the ground and excited states are competitive with other state-of-the-art approaches, but at a fraction of their computational cost. The composite boson mapping here introduced can be readily applied to frustrated many-body systems where most methodologies face significant hurdles.Comment: 8 pages, 4 figure

Staircase of crystal phases of hard-core bosons on the Kagome lattice

We study the quantum phase diagram of a system of hard-core bosons on the Kagome lattice with nearest-neighbor repulsive interactions, for arbitrary densities, by means of the hierarchical mean field theory and exact diagonalization techniques. This system is isomorphic to the spin S=1/2 XXZ model in presence of an external magnetic field, a paradigmatic example of frustrated quantum magnetism. In the non-frustrated regime, we find two crystal phases at densities 1/3 and 2/3 that melt into a superfluid phase when increasing the hopping amplitude, in semi-quantitative agreement with quantum Monte Carlo computations. In the frustrated regime and away from half-filling, we find a series of plateaux with densities commensurate with powers of 1/3. The broader density plateaux (at densities 1/3 and 2/3) are remnants of the classical degeneracy in the Ising limit. For densities near half-filling, this staircase of crystal phases melts into a superfluid, which displays finite chiral currents when computed with clusters having an odd number of sites. Both the staircase of crystal phases and the superfluid phase prevail in the non-interacting limit, suggesting that the lowest dispersionless single-particle band may be at the root of this phenomenon

Enseñanza-aprendizaje por indagación de los contenidos relativos a la salud en el grado de educación primaria

En este trabajo se quiere poner de manifiesto la importancia que conlleva una adecuada formación del futuro profesor de educación primaria en los contenidos del ámbito de la salud. Se analiza cómo tiene lugar la enseñanza de estos contenidos dentro del ámbito universitario en la Universidad deValladolid, en relación a los planes de estudio actuales así como a la legislación existente del currículum de educación primaria. Dentro de las competencias que ha de adquirir el futuro docente se contemplan aquellas que se adquieren a través de experiencias motivadoras en su paso por las aulas universitarias. Con este enfoque es con el que se ha planteado la impartición de las enseñanzas que se contemplan en la asignatura de educación para la salud en Educación Primaria. Se propone para este tipo de enseñanza una metodología indagatoria para que los futuros maestros adquieran las competencias necesarias en el ámbito de la salud. El uso del material didáctico que ofrece el proyecto europeo PROFILES («Professional Reflection-OrientedFocusonInquiry-basedLearning and EducationthroughScience», así como su filosofía de la enseñanza-aprendizaje basada en la indagación hace posible llevar la estrategia al aula

Chiral phases of two-dimensional hard-core bosons with frustrated ring-exchange

We study the zero temperature phase diagram of two-dimensional hard-core bosons on a square lattice with nearest neighbour and plaquette (ring-exchange) hoppings, at arbitrary densities, by means of a hierarchical mean-field theory. In the frustrated regime, where quantum Monte Carlo suffers from a sign problem, we find a rich phase diagram where exotic states with nonzero chirality emerge. Among them, novel insulating phases, characterized by nonzero bond-chirality and plaquette order, are found over a large region of the parameter space. In the unfrustrated regime, the hierarchical mean-field approach improves over the standard mean-field treatment as it is able to capture the transition from a superfluid to a valence bond state upon increasing the strength of the ring-exchange term, in qualitative agreement with quantum Monte Carlo results

El método Delphi como herramienta de diseño curricular de la educación para la salud en la formación del profesor de primaria

En este trabajo se quiere poner de manifiesto la importancia que conlleva una adecuada formación del futuro profesor de educación primaria en el ámbito de la salud para adquirir las competencias necesarias para el ejercicio adecuado de su profesión. Para ello, presentamos un análisis "Delphi" para tratar de descubrir los puntos clave en la enseñanza-aprendizaje de los contenidos referidos a la salud que pueden mejorar los hábitos saludables en la sociedad actual. Es evidente la importancia de mejorar e intensificar eso shábitos en la sociedad en general, y más en particular de edades tempranas, como son los alumnos durante la educación primaria y secundaria. Sin embargo, resulta difícil desentrañar qué aspectos fallan en la práctica educativa así como cuáles se consideran los temas que debería conocer un futuro profesor de educación primaria. A través de sucesivas encuestas a distintos colectivos relacionados con el ámbito de la enseñanza y de la salud, tratamos de encontrar las claves para mejorar la educación para la salud y enfatizar la necesidad de incorporar y mejorar los hábitos saludables en los estudiantes. El estudio se centra en los alumnos de grado de educación primaria de la Universidad de Valladolid

Density-dependent synthetic magnetism for ultracold atoms in optical lattices

Raman-assisted hopping can allow for the creation of density-dependent synthetic magnetism for cold neutral gases in optical lattices. We show that the density-dependent fields lead to a non-trivial interplay between density modulations and chirality. This interplay results in a rich physics for atoms in two-leg ladders, characterized by a density-driven Meissner- to vortex-superfluid transition, and a non-trivial dependence of the density imbalance between the legs. Density-dependent fields also lead to intriguing physics in square lattices. In particular, it leads to a density-driven transition between a non-chiral and a chiral superfluid, both characterized by non-trivial charge density-wave amplitude. We finally show how the physics due to the density-dependent fields may be easily probed in experiments by monitoring the expansion of doublons and holes in a Mott insulator, which presents a remarkable dependence on quantum fluctuations.Comment: 5 pages, 4 figure

European periphery crises, international financial markets, and democracy: moving towards a globalized neofeudalism?

This paper analyzes the origin and causes of the recent economic and financial crises, mainly for the countries located in the periphery of the European Union (EU), as well as their evolution and transformation into social, political, and institutional crises. After explaining the differential impact of the crises on EU member economies and critically analysing the unsuccessful orthodox neoclassical policies implemented by governments and international institutions to try to manage and resolve them, we propose some alternative economic policy measures for the EU. Furthermore, we analyze how the economic policies developed thus far not only are unable to resolve the current crisis pattern but also actually entail a risk to the present democratic models by transferring the legitimate control over governments from citizens and democratic parliaments to unelected, non-representative international financial markets.

Fray Luis de Granada, teólogo

Tras una introducción histórica en la que se describe el contexto espiritual y teológico en que se mueve Fray Luis de Granada, el A. desarrolla su visión en torno al quehacer teológico y a las dos formas principales de hacer teología (teología escolástica y teología mística). En el contexto histórico, Huerga destaca las relaciones de Fray Luis con el Colegio de San Gregorio de Valladolid y el juicio que su figura de teólogo le merece a Gonzalo de Arriaga. En este contexto, se destaca la acertada visión que Cano tiene de la posición de Fray Luis ante la teología, y el desacertado juicio que el mismo Cano emite en torno a esta posición. En efecto, según Cano, la Iglesia podía reprender gravemente a Fray Luis el hecho de «que pretendió hacer contemplativos y perfectos a todos, y enseñar al pueblo en castellano» y, por lo tanto, hacer la teología asequible a todos. Sin embargo, aquí radica justamente la grandeza de Fray Luis: haber sabido destacar el carácter sapiencial de la teología y su universalidad, haber distinguido coherentemente entre teología especulativa o escolástica y teología afectiva o mística, y haber sabido sintetizar los rasgos esenciales de ambas, poniendo de relieve que el principal maestro de esta última es el Espíritu Santo

Impact of introducing human immunodeficiency virus testing, treatment and care in a tuberculosis clinic in rural Kenya

SETTING: In July 2005, Médecins Sans Frontières and the Ministry of Health, Kenya, implemented an integrated tuberculosis-human immunodeficiency virus (TB-HIV) programme in western Kenya. OBJECTIVE: To evaluate the impact of an integrated TB-HIV programme on patient care and TB programme outcomes. DESIGN: Retrospective evaluation of three time periods: before (January-June 2005), shortly after (January-June 2006) and medium term after (January-December 2007) the implementation of the integrated programme. RESULTS: Respectively 79% and 91% of TB patients were HIV tested shortly and at medium term after service integration. The HIV-positive rate varied from 96% before the intervention to respectively 88% (305/347) and 74% (301/405) after. The estimated number of HIV-positive cases was respectively 303, 323 and 331 in the three periods. The proportion of patients receiving cotrimoxazole prophylaxis increased significantly from 47% (142/303) to 94% (303/323) and 86% (285/331, P < 0.05). Before the intervention, 87% (171/197) of the TB-HIV patients would have been missed when initiating antiretroviral treatment, compared to respectively 29% (60/210) and 36% (78/215) after the integration. The TB programme success rate increased from 56% (230/409) to 71% (319/447) in the third period (P < 0.05); however, there was no significant decrease in the default rate: 20% to 22% (P = 0.66) and 18% (P = 0.37). CONCLUSION: Integrated TB-HIV care has a very positive impact on the management of TB-HIV patients and on TB treatment outcomes