Anàlisi territorial de la preinscripció al sistema universitari públic de Catalunya. L’efecte distància–temps des del domicili habitual en l’elecció de centre i estudi.

[cat] La mobilitat obligada per raó d'estudi analitza els desplaçaments dels alumnes entre el seu lloc de residencia i el lloc d'estudi en qualsevol de les etapes educatives, des dels ensenyaments primaris obligatoris fins als superiors. En aquest sentit, doncs, el fenomen de la mobilitat es consubstancial a la mateixa universitat ja des dels seus inicis esdevenint avui un fenomen complex fent-se necessari, per entendre'I en tota la seva magnitud, identificar-ne tant els diferents actors que hi intervenen com les diferents escales geogràfiques que abasta, el mare formal en el que es desenvolupa i la seva direccionalitat. En aquest context, l'objectiu principal que persegueix aquesta recerca es el d'esbrinar els criteris i patrons que determinen l'elecció de centre i estudi per part dels estudiants residents a Catalunya que accedeixen per primer cop a l'oferta de titulacions de les universitats catalanes que participen del procés de preinscripció (UB, UAB, UPC, UPF, Udl, UdG, URV i UVic) tot confeccionant un mapa de fluxos de la mobilitat d'aquest col·lectiu al llarg del per1ode que abasta del curs 2000-01 al 2013-14 per a, tal vegada, obtenir orientacions sobre el seu comportament futur. D'aquesta manera, emprant com a font principal de dades els fitxers del sistema UNEIX sobre els estudiants matriculats de nou accés en cadascuna d'aquestes universitats per a cada any acadèmic analitzat i a partir de la comarca d'origen d'aquest estudiantat (aquella on tenen establert el seu domicili habitual, generalment el familiar) s'han determinat en primer lloc l'àrea d'influència i de captació d'aquestes institucions per tal d'esbrinar quina es la seva presencia i pes específic en el territori i, en segon terme, s'han identificat tres dinàmiques de comportament dels estudiant a l'hora d'escollir centre i estudi segons sigui la distancia que separa aquest domicili de la ubicació de l'oferta universitària. Tot plegat, pretén resoldre el problema que planteja el desconeixement existent en l'actualitat de les relacions complexes que s'estableixen entre la selecció d'estudis universitaris i centre amb les xarxes de transport i la mobilitat induïda dels estudiants del sistema universitari de Catalunya.[eng] Mobility forced by study reasons analyses the students' travels between their place of residence and the study location in any of the formative stages: from mandatory elementary studies to higher education. In this sense, the mobility phenomenon is consubstantial to university itself from the very start, currently growing up to be a complex phenomenon. In order to be able to understand it to its fullest, it is then necessary to identify the various actors participating in it, the different geographical scales reached, as well as the formal framework in which it is carried out, and its directionality.In this contex the main objective of this research is to find out the criteria and patterns that prompt the choice of centre and studies by the students residing in Catalonia accessing for the very first time the degree's offer from the Catalan universities taking part of the pre­ registration process (UB, UAB, UPC, UPF, Udl , UdG, URV and UVic), by composing a flow map of this collective's mobility within the period covering the academic years 2000/01 to 2013/ 14, so as to perhaps obtain orientations on their future behaviour.In this way, and by using as a primary source the data from the UNEIX system files on freshman students, sorted by each of the aforementioned universities and academic year, and based on the county of origin of this student body (the one where their permanent address is estabilshed, generally this being the home address), the following has been determined: first, these institutions' influence and acquisition area in order to find out their actual presence and specific weight within the territory; and, second, three students' behaviour dynamics regarding their centre and studies choice, depending on the distance separating their place of residence and the location of the university offer.All of that hopes to solve the problem resulting from the currently existing ignorance on the complex relations established vis a vis the university studies and centre selection, and the transport network and induced mobility of the Catalan university system's students

Scanning the Parameter Space of Holographic Superconductors

We study various physical quantities associated with holographic s-wave superconductors as functions of the scaling dimensions of the dual condensates. A bulk scalar field with negative mass squared $m^2$, satisfying the Breitenlohner-Freedman stability bound and the unitarity bound, and allowed to vary in $0.5$ unit intervals, were considered. We observe that all the physical quantities investigated are sensitive to the scaling dimensions of the dual condensates. For all the $m^2$, the characteristic lengths diverge at the critical temperature in agreement with the Ginzburg-Landau theory. The Ginzburg-Landau parameter, obtained from these length scales indicates that the holographic superconductors can be type I or type II depending on the charge and the scaling dimensions of the dual condensates. For a fixed charge, there exists a critical scaling dimension, above which a holographic superconductor is type I, below which it becomes a type II.Comment: 24 pages 47 figure

Non-Equilibrium Field Dynamics of an Honest Holographic Superconductor

Most holographic models of superconducting systems neglect the effects of dynamical boundary gauge fields during the process of spontaneous symmetry-breaking. Usually a global symmetry gets broken. This yields a superfluid, which then is gauged "weakly" afterwards. In this work we build (and probe the dynamics of) a holographic model in which a local boundary symmetry is spontaneously broken instead. We compute two-point functions of dynamical non-Abelian gauge fields in the normal and in the broken phase, and find non-trivial gapless modes. Our AdS3 gravity dual realizes a p-wave superconductor in (1+1) dimensions. The ground state of this model also breaks (1+1)-dimensional parity spontaneously, while the Hamiltonian is parity-invariant. We discuss possible implications of our results for a wider class of holographic liquids.Comment: 32 pages, 12 figures; v3: string theory derivation of setup added (section 3.1), improved presentation, version accepted by JHEP; v2: paragraph added to discussion, figure added, references added, typos correcte

Non-equilibrium Condensation Process in a Holographic Superconductor

We study the non-equilibrium condensation process in a holographic superconductor. When the temperature T is smaller than a critical temperature T_c, there are two black hole solutions, the Reissner-Nordstrom-AdS black hole and a black hole with a scalar hair. In the boundary theory, they can be regarded as the supercooled normal phase and the superconducting phase, respectively. We consider perturbations on supercooled Reissner-Nordstrom-AdS black holes and study their non-linear time evolution to know about physical phenomena associated with rapidly-cooled superconductors. We find that, for T<T_c, the initial perturbations grow exponentially and, eventually, spacetimes approach the hairy black holes. We also clarify how the relaxation process from a far-from-equilibrium state proceeds in the boundary theory by observing the time dependence of the superconducting order parameter. Finally, we study the time evolution of event and apparent horizons and discuss their correspondence with the entropy of the boundary theory. Our result gives a first step toward the holographic understanding of the non-equilibrium process in superconductors.Comment: 20 pages, 7 figure

Introduction to Holographic Superconductors

These lectures give an introduction to the theory of holographic superconductors. These are superconductors that have a dual gravitational description using gauge/gravity duality. After introducing a suitable gravitational theory, we discuss its properties in various regimes: the probe limit, the effects of backreaction, the zero temperature limit, and the addition of magnetic fields. Using the gauge/gravity dictionary, these properties reproduce many of the standard features of superconductors. Some familiarity with gauge/gravity duality is assumed. A list of open problems is included at the end.Comment: 34 pages, 10 figures, to appear in the proceedings of the 5th Aegean Summer School, "From Gravity to Thermal Gauge Theories: the AdS/CFT Correspondence"; v2: references adde

Analytical study on holographic superconductors in external magnetic field

We investigate the holographic superconductors immersed in an external magnetic field by using the analytical approach. We obtain the spatially dependent condensate solutions in the presence of the magnetism and find analytically that the upper critical magnetic field satisfies the relation given in the Ginzburg-Landau theory. We observe analytically the reminiscent of the Meissner effect where the magnetic field expels the condensate. Extending to the D-dimensional Gauss-Bonnet AdS black holes, we examine the influence given by the Gauss-Bonnet coupling on the condensation. Different from the positive coupling, we find that the negative Gauss-Bonnet coupling enhances the condensation when the external magnetism is not strong enough.Comment: revised version, to appear in JHE