Light-cone quantization of two dimensional field theory in the path integral approach

A quantization condition due to the boundary conditions and the compatification of the light cone space-time coordinate $x^-$ is identified at the level of the classical equations for the right-handed fermionic field in two dimensions. A detailed analysis of the implications of the implementation of this quantization condition at the quantum level is presented. In the case of the Thirring model one has selection rules on the excitations as a function of the coupling and in the case of the Schwinger model a double integer structure of the vacuum is derived in the light-cone frame. Two different quantized chiral Schwinger models are found, one of them without a $\theta$-vacuum structure. A generalization of the quantization condition to theories with several fermionic fields and to higher dimensions is presented.Comment: revtex, 14 p

Mechanical systems subjected to generalized nonholonomic constraints

We study mechanical systems subject to constraint functions that can be dependent at some points and independent at the rest. Such systems are modelled by means of generalized codistributions. We discuss how the constraint force can transmit an impulse to the motion at the points of dependence and derive an explicit formula to obtain the ``post-impact'' momentum in terms of the ``pre-impact'' momentum.Comment: 24 pages, no figure

Global controllability tests for geometric hybrid control systems

Hybrid systems are characterized by having an interaction between continuous dynamics and discrete events. The contribution of this paper is to provide hybrid systems with a novel geometric formulation so that controls can be added. Using this framework we describe some new global controllability tests for hybrid control systems exploiting the geometry and the topology of the set of jump points, where the instantaneous change of dynamics take place. Controllability is understood as the existence of a feasible trajectory for the system joining any two given points. As a result we describe examples where none of the continuous control systems are controllable, but the associated hybrid system is controllable because of the characteristics of the jump set.Comment: 27 pages, 5 figure

Completeness in supergravity constructions

We prove that the supergravity r- and c-maps preserve completeness. As a consequence, any component H of a hypersurface {h=1} defined by a homogeneous cubic polynomial such that -d^2 h is a complete Riemannian metric on H defines a complete projective special Kahler manifold and any complete projective special Kahler manifold defines a complete quaternionic Kahler manifold of negative scalar curvature. We classify all complete quaternionic Kahler manifolds of dimension less or equal to 12 which are obtained in this way and describe some complete examples in 16 dimensions.Comment: 29 page

Conserved Ising Model on the Human Connectome

Dynamical models implemented on the large scale architecture of the human brain may shed light on how function arises from the underlying structure. This is the case notably for simple abstract models, such as the Ising model. We compare the spin correlations of the Ising model and the empirical functional brain correlations, both at the single link level and at the modular level, and show that their match increases at the modular level in anesthesia, in line with recent results and theories. Moreover, we show that at the peak of the specific heat (the \it{critical state}) the spin correlations are minimally shaped by the underlying structural network, explaining how the best match between structure and function is obtained at the onset of criticality, as previously observed. These findings confirm that brain dynamics under anesthesia shows a departure from criticality and could open the way to novel perspectives when the conserved magnetization is interpreted in terms of an homeostatic principle imposed to neural activity

Non-extremal Black Holes, Harmonic Functions, and Attractor Equations

We present a method which allows to deform extremal black hole solutions into non-extremal solutions, for a large class of supersymmetric and non-supersymmetric Einstein-Vector-Scalar type theories. The deformation is shown to be largely independent of the details of the matter sector. While the line element is dressed with an additional harmonic function, the attractor equations for the scalars remain unmodified in suitable coordinates, and the values of the scalar fields on the outer and inner horizon are obtained from their fixed point values by making specific substitutions for the charges. For a subclass of models, which includes the five-dimensional STU-model, we find explicit solutions.Comment: 33 page

Social educators at schools in Andalusia: Profile and professional development

El artículo presenta parte de los resultados de un proyecto de investigación sobre el impacto de la implementación y la evolución del perfil profesional de los educadores y educadoras sociales en las escuelas de Andalucía. La metodología utilizada descansa en una perspectiva de corte evaluativo. En la misma, mediante una metodología mixta, se ha conjugado el análisis documental, los cuestionarios y los estudios de caso. A partir de ahí se desvelan los resultados vinculados el perfil, las funciones y el impacto que ha tenido mencionada figura en los centros educativos, teniendo en cuenta su desarrollo profesional en distintos niveles (legislativo, educativo y administrativo) y en relación a la valoración que hacen otros agentes educativos. Dichos resultados se articulan en torno a cuatro sub-apartados relacionados con las categorías definidas en este estudio: labor del educador-a, percepciones sobre y desde los educadores-as sociales, funciones y desempeño profesional y condicionantes de su labor y participación. Finalmente, se muestran algunas conclusiones en clave propositiva que muestran vías por las que seguir fortaleciendo esta necesaria figura en el sistema educativo, apostando por fortalecer las funciones que se perciben y manifiestan más necesarias en los centros e identificando las principales dificultades con las que se ha encontrado su laborThis paper presents part of the results of a research project on the impact of the implementation and evolution of the professional profile of social educators at schools in Andalusia. The methodology used rests on an evaluative perspective. In this process, the documentary analysis, the questionnaires and the case studies have been combined by a mixed methodology. In this point, the results linked to the profile, functions and impact of the social educator are revealed, taking into account their professional development at different levels (legislative, educational and administrative) and in relation to the assessment that make other educational agents. These results are articulated around four sub-sections related to the categories defined in this study: the work of the educator, perceptions about and from the social educators, functions and professional performance and conditioning factors of their work and participation. Finally, some conclusions are shown in a proactive key that show ways to continue strengthening this necessary figure in the education system, betting on strengthening the functions that are perceived and manifested most necessary in the centers and identifying the main difficulties with which found his wor

Silicon-based three-dimensional microstructures for radiation dosimetry in hadrontherapy

In this work, we propose a solid-state-detector for use in radiation microdosimetry. This device improves the performance of existing dosimeters using customized 3D-cylindrical microstructures etched inside silicon. The microdosimeter consists of an array of micro-sensors that have 3D-cylindrical electrodes of 15 μm diameter and a depth of 5 μm within a silicon membrane, resulting in a well-defined micrometric radiation sensitive volume. These microdetectors have been characterized using an 241Am source to assess their performance as radiation detectors in a high-LET environment. This letter demonstrates the capability of this microdetector to be used to measure dose and LET in hadrontherapy centers for treatment plan verification as part of their patient-specific quality control program