Coulomb integrals and conformal blocks in the AdS3-WZNW model

We study spectral flow preserving four-point correlation functions in the AdS3-WZNW model using the Coulomb gas method on the sphere. We present a multiple integral realization of the conformal blocks and explicitly compute amplitudes involving operators with quantized values of the sum of their spins, i.e., requiring an integer number of screening charges of the first kind. The result is given as a sum over the independent configurations of screening contours yielding a monodromy invariant expansion in powers of the worldsheet moduli. We then examine the factorization limit and show that the leading terms in the sum can be identified, in the semiclassical limit, with products of spectral flow conserving three-point functions. These terms can be rewritten as the m-basis version of the integral expression obtained by J. Teschner from a postulate for the operator product expansion of normalizable states in the H3+-WZNW model. Finally, we determine the equivalence between the factorizations of a particular set of four-point functions into products of two three-point functions either preserving or violating spectral flow number conservation. Based on this analysis we argue that the expression for the amplitude as an integral over the spin of the intermediate operators holds beyond the semiclassical regime, thus corroborating that spectral flow conserving correlators in the AdS3-WZNW model are related by analytic continuation to correlation functions in the H3+-WZNW model.Comment: 28 pages; references modified, published versio

Papel del profesor motivado en la educación emprendedora en España

El propósito de esta investigación es debatir y medir cómo se está implantando la competencia emprendedora como competencia transversal en el sistema escolar en Europa y en particular en España. Se sitúa dentro del ámbito de la economía de la educación, siguiendo las corrientes de estudio del impacto de la educación en la iniciativa emprendedora y su importancia para el desarrollo socioeconómico de Europa. Se ocupa del papel del profesor, objeto de debate en la implantación de las políticas europeas sobre competencia emprendedora. Se discute la aplicación del concepto de “emprendimiento” en el nivel escolar. La investigación práctica se basa en el análisis de datos. Como sistema para la recolección y medición de datos se utiliza y adapta al contexto español el cuestionario Measurement Tool for Enterprise Education desarrollado y aplicado en Finlandia. Este método, validado por la UE, evalúa la disposición del profesorado a fomentar en el alumno una enseñanza orientada al emprendimiento y analiza sus condicionamientos. El artículo se centra en el estudio de las respuestas de 173 profesores de distintos niveles educativos que manifestaron sentirse “motivados” a promover la competencia emprendedora. Los resultados muestran los condicionamientos en la actitud del profesor hacia la puesta en práctica de actividades de competencia emprendedora, así como diferencias en función de la variable titularidad de centro. Como conclusión destacamos la escasa implantación como competencia transversal al estar muy condicionada por el nivel de estudio y asignatura impartida.The purpose of this paper is to discuss and measure how entrepreneurship is implemented as transversal competence in the school system in Europe and in particular in Spain. In the field of economics of education, we contribute to the discussion about the impact of education on entrepreneurship intention as key element for Europe’s socio-economic development. We focus on role of teacher as center of debate in European policies on entrepreneurship. Concept of “entrepreneurship” at school level is discussed. Research is based in data analysis collected by self-assessment questionnaire Measurement Tool for Enterprise Education. This tool has been developed and applied in Finland and adapted to the Spanish context. This method, validated by the EU to measure entrepreneurial education politics implementation, evaluates willingness of teachers to promote entrepreneurship- oriented instruction. The data consist in 173 teachers of different education levels categorized as “motivated” to promote entrepreneurial competence. The results show differences in teacher’s attitude as condition for entrepreneurial competence implementation, as well as significant differences in entrepreneurship education development between private and public school. In conclusion, we emphasize a lack of implementation as a cross-curricular competence because it is highly conditioned by level and subject taught

The Mexican intertemporal budget constraint: Persistent signals of an eventual collapse

This paper examines the sustainability of the Mexican current account deficit prior to the December 1994 crisis. It tests whether or not the Mexican economy was satisfying its intertemporal budget constraint, and finds that signals of possible trouble without a change in policies were present long before the crisis. The tests used are based on the Wickens-Uctum criterion for the sustainability of current account deficits, extended to include the case of possible interventions.intertemporal budget constraint, current account, sustainability of current account deficit, Mexico

Quantum critical point and superconducting dome in the pressure phase diagram of o-TaS3

We measure the electrical resistance of o-TaS3 between 1K and 300K under pressures up to 20GPa. We observe a gradual decrease of the charge density wave transition temperature with increasing pressure P following a mean-field quantum fluctuation power law with a quantum critical point at a pressure Pc = 11.5GPa. Around the quantum critical point we observe a superconducting dome with a maximum superconducting transition temperature Tc = 3.1K. Such dome is similar to superconducting domes around other types of order suggesting that the QCP is directly responsible for the enhancement of superconductivity through a universal mechanism still not well understood.Comment: To be published in PRB as a Rapid Communication. 11 pages with 4 figure