Symmetries of the free Schrödinger equation in the non-commutative plane

We study all the symmetries of the free Schr odinger equation in the non-commu- tative plane. These symmetry transformations form an infinite-dimensional Weyl algebra that appears naturally from a two-dimensional Heisenberg algebra generated by Galilean boosts and momenta. These infinite high symmetries could be useful for constructing non-relativistic interacting higher spin theories. A finite-dimensional subalgebra is given by the Schröodinger algebra which, besides the Galilei generators, contains also the dilatation and the expansion. We consider the quantization of the symmetry generators in both the reduced and extended phase spaces, and discuss the relation between both approaches.

Symmetries of the free Schrödinger equation in the non-commutative plane

We study all the symmetries of the free Schrödinger equation in the non-commu- tative plane. These symmetry transformations form an infinite-dimensional Weyl algebra that appears naturally from a two-dimensional Heisenberg algebra generated by Galilean boosts and momenta. These infinite high symmetries could be useful for constructing non-relativistic interacting higher spin theories. A finite-dimensional subalgebra is given by the Schröodinger algebra which, besides the Galilei generators, contains also the dilatation and the expansion. We consider the quantization of the symmetry generators in both the reduced and extended phase spaces, and discuss the relation between both approaches.

Europa als ulls dels Annales (1093-1933)

During this first third of this century, the continent of Europe witnessed far-reaching territorial transformations in the nineteenth century model. To some extent, the setting wich had inspired the epistemological structure of the French regional school was being replaced by one in which -at least to externa1 appearances- the relationship between the physical environment and human activities was much less evident. The adaptation of the theoretical and methodological context to the new Europe seems to take the form of a non-lineal evolution, for in the latter years of the period examined, evolutionary tendencies indicate a return to the more classical model. In this way, the growing interest which the publication had shown in Atlantic Europe and topics of a more economic nature, was truncated. The traditional settings --especially the Mediterranean- came to the fore again and interest in rural societies was renewed. Likewise, the monographic studies which had demonstrated distinct functional objectives in the midtwenties, recovered elements of ecological explanation, and the search for the relationship between environment and society

La dimensió social del moviment priscil·lianista en el context de l'antiguitat tardana. Heretgia, lluita contra la institucionalització eclesiàstica i contestació social.

L'any 385, Priscil·lià i la resta del grup priscil·lianista era condemnat a la ciutat de Trèveris i, fruit de la ingerència determinant de l'usurpador Magne Màxim, es convertia en el primer heretge ajusticiat pel poder secular en nom de l'Església. Els fets de Trèveris, per bé que van significar el final de la disputa entre dos grups amb posicions antagòniques vers les característiques del nou cristianisme institucionalitzat, no van aconseguir acabar amb el priscil·lianisme. El moviment perdurà, especialment a la província de la Gallaecia, i Priscil·lià va esdevenir venerat com màrtir. L'Església, mentrestant, es fracturava per culpa de la competència jurisdiccional entre la institució clerical i el poder imperial. Aquest treball intenta ser un estat de la qüestió respecte a la dimensió social d'un moviment que, més enllà de l'eterna discussió entre la seva possible catalogació com a ortodòxia o heterodòxia, intenta contextualitzar el priscil·lianisme en el seu marc històric i els convulsos anys de les transformacions de l'antiguitat tardana.

Políticas públicas y sustentabilidad en las zonas desfavorecidas y de montaña en España

El presente trabajo aborda una visión global de la acción pública en los espacios que, en principio, han sido oficial o/y institucionalmente definidos como zonas desfavorecidas o zonas de montaña en España. Territorios, básicamente rurales, que en España muestran un notable grado de heterogeneidad en cuanto a sus estructuras económicas, sociales y culturales, además de caracterizarse por unas estructuras ecológicas igualmente dispares. Esta realidad poliédrica en los últimos años se está viendo condicionada por cuatro factores: las transformaciones internas del sector agroalimentario; los cambios en la organización espacial de la actividad y de la población que son consecuencia de la reestructuración del capitalismo; por las nuevas funciones socioeconómicas, socioculturales y medioambientales que desempeñan estos espacios; y, por el impacto, a veces contradictorio, de las diversas políticas que se implementan sobre ellos, y que se desenvuelven, cada vez más nítidamente, bajo el paradigma del desarrollo sostenible institucional.

Análisis discursivo de las actitudes lingüísticas de los escolares de origen inmigrante en Cataluña

La continua llegada de población inmigrante a los países de la Europa Occidental está produciendo transformaciones en estas sociedades. Evidentemente, la sociedad catalana no es ajena a estos cambios y, año tras año, ve incrementado el número de recién llegados/ as procedentes de orígenes geográficos, culturales y lingüísticos muy diversos. Estas personas, en ocasiones sin un conocimiento previo, se encuentran con las peculiaridades socioculturales y lingüísticas de la sociedad receptora. En el caso de Cataluña, nos interesa destacar la cuestión lingüística, a la cual se han dedicado muchos esfuerzos durante los últimos años en un intento de acercarse a una situación de normalidad en lo referente al conocimiento y uso de la lengua catalana. En el presente artículo se presentan los principales resultados de una investigación centrada en el análisis de los discursos sobre los que anclan las actitudes lingüísticas de los escolares de origen inmigrante en Cataluña. La técnica de investigación social utilizada ha sido la entrevista en profundidad semidirigida, realizando el análisis del contenido de las mismas a partir del «Análisis de contenido temático basado en categorías» (Bardin, 1986). Las conclusiones más relevantes indican que, por encima del Área de Origen o la Condición Lingüística Familiar, la principal variable que permite articular los discursos detectados es la que se puede denominar «Satisfacción y Percepción de Valoración e Integración Escolar y Social», de tal manera que los jóvenes de origen inmigrante que se sienten más valorados e integrados escolar y socialmente desarrollan mejores actitudes hacia la lengua catalana y castellana. Este hecho tiene claras repercusiones respecto las generalizaciones reduccionistas y estereotipadas que vinculan un área de origen con unas determinadas actitudes hacia las lenguas oficiales en Cataluña, así como de cara a la política lingüística y las ideologías lingüísticas de la sociedad en general.

El naixement d'un vilar medieval: Moredell (Gironès) en època carolíngia

This is the description of the birth, development and transformations of a small rural community in carolingian epoch through the written documentation and the analysis of the landscape.

Extreme-value distributions and renormalization group

In the classical theorems of extreme value theory the limits of suitably rescaled maxima of sequences of independent, identically distributed random variables are studied. The vast majority of the literature on the subject deals with affine normalization. We argue that more general normalizations are natural from a mathematical and physical point of view and work them out. The problem is approached using the language of renormalization-group transformations in the space of probability densities. The limit distributions are fixed points of the transformation and the study of its differential around them allows a local analysis of the domains of attraction and the computation of finite-size corrections.

Juventud, políticas públicas y crisis en España: ¿Triángulo mágico o triángulo de las Bermudas?

In times of crisis, the youth policies are experiencing enormous cutbacks and transformations to the point that we are wondering whether they really exist as public policies with their own entity. The situation in which many young people find themselves in Spain leads them to wonder where the traditional protection networks are: The family, the NGO’s or the Welfare State, when they are really needed. Our objective in this article is to show and discuss the situation of the youth policies in Spain in the present context of social austerity and drastic cutbacks. We carry out this analysis from the parameters of the magical triangle that unite policies, research and social work with young people

The UlaG protein familly defines novel structural and functional motifs grafted on an ancient RNase fold

Background: Bacterial populations are highly successful at colonizing new habitats and adapting to changing environmental conditions, partly due to their capacity to evolve novel virulence and metabolic pathways in response to stress conditions and to shuffle them by horizontal gene transfer (HGT). A common theme in the evolution of new functions consists of gene duplication followed by functional divergence. UlaG, a unique manganese-dependent metallo-b-lactamase (MBL) enzyme involved in L-ascorbate metabolism by commensal and symbiotic enterobacteria, provides a model for the study of the emergence of new catalytic activities from the modification of an ancient fold. Furthermore, UlaG is the founding member of the so-called UlaG-like (UlaGL) protein family, a recently established and poorly characterized family comprising divalent (and perhaps trivalent)metal-binding MBLs that catalyze transformations on phosphorylated sugars and nucleotides. Results: Here we combined protein structure-guided and sequence-only molecular phylogenetic analyses to dissect the molecular evolution of UlaG and to study its phylogenomic distribution, its relatedness with present-day UlaGL protein sequences and functional conservation. Phylogenetic analyses indicate that UlaGL sequences are present in Bacteria and Archaea, with bona fide orthologs found mainly in mammalian and plant-associated Gramnegative and Gram-positive bacteria. The incongruence between the UlaGL tree and known species trees indicates exchange by HGT and suggests that the UlaGL-encoding genes provided a growth advantage under changing conditions. Our search for more distantly related protein sequences aided by structural homology has uncovered that UlaGL sequences have a common evolutionary origin with present-day RNA processing and metabolizing MBL enzymes widespread in Bacteria, Archaea, and Eukarya. This observation suggests an ancient origin for the UlaGL family within the broader trunk of the MBL superfamily by duplication, neofunctionalization and fixation. Conclusions: Our results suggest that the forerunner of UlaG was present as an RNA metabolizing enzyme in the last common ancestor, and that the modern descendants of that ancestral gene have a wide phylogenetic distribution and functional roles. We propose that the UlaGL family evolved new metabolic roles among bacterial and possibly archeal phyla in the setting of a close association with metazoans, such as in the mammalian gastrointestinal tract or in animal and plant pathogens, as well as in environmental settings. Accordingly, the major evolutionary forces shaping the UlaGL family include vertical inheritance and lineage-specific duplication and acquisition of novel metabolic functions, followed by HGT and numerous lineage-specific gene loss events.

Drumming in immersive virtual reality: the body shapes the way we play

It has been shown that it is possible to generate perceptual illusions of ownership in immersive virtual reality (IVR) over a virtual body seen from first person perspective, in other words over a body that visually substitutes the person's real body. This can occur even when the virtual body is quite different in appearance from the person's real body. However, investigation of the psychological, behavioral and attitudinal consequences of such body transformations remains an interesting problem with much to be discovered. Thirty six Caucasian people participated in a between-groups experiment where they played a West-African Djembe hand drum while immersed in IVR and with a virtual body that substituted their own. The virtual hand drum was registered with a physical drum. They were alongside a virtual character that played a drum in a supporting, accompanying role. In a baseline condition participants were represented only by plainly shaded white hands, so that they were able merely to play. In the experimental condition they were represented either by a casually dressed dark-skinned virtual body (Casual Dark-Skinned - CD) or by a formal suited light-skinned body (Formal Light-Skinned - FL). Although participants of both groups experienced a strong body ownership illusion towards the virtual body, only those with the CD representation showed significant increases in their movement patterns for drumming compared to the baseline condition and compared with those embodied in the FL body. Moreover, the stronger the illusion of body ownership in the CD condition, the greater this behavioral change. A path analysis showed that the observed behavioral changes were a function of the strength of the illusion of body ownership towards the virtual body and its perceived appropriateness for the drumming task. These results demonstrate that full body ownership illusions can lead to substantial behavioral and possibly cognitive changes depending on the appearance of the virtual body. This could be important for many applications such as learning, education, training, psychotherapy and rehabilitation using IVR.

Gaia photometry for white dwarfs

Context. White dwarfs can be used to study the structure and evolution of the Galaxy by analysing their luminosity function and initial mass function. Among them, the very cool white dwarfs provide the information for the early ages of each population. Because white dwarfs are intrinsically faint only the nearby (~ 20 pc) sample is reasonably complete. The Gaia space mission will drastically increase the sample of known white dwarfs through its 5-6 years survey of the whole sky up to magnitude V = 20-25. Aims. We provide a characterisation of Gaia photometry for white dwarfs to better prepare for the analysis of the scientific output of the mission. Transformations between some of the most common photometric systems and Gaia passbands are derived. We also give estimates of the number of white dwarfs of the different galactic populations that will be observed. Methods. Using synthetic spectral energy distributions and the most recent Gaia transmission curves, we computed colours of three different types of white dwarfs (pure hydrogen, pure helium, and mixed composition with H/He = 0.1). With these colours we derived transformations to other common photometric systems (Johnson-Cousins, Sloan Digital Sky Survey, and 2MASS). We also present numbers of white dwarfs predicted to be observed by Gaia. Results. We provide relationships and colour-colour diagrams among different photometric systems to allow the prediction and/or study of the Gaia white dwarf colours. We also include estimates of the number of sources expected in every galactic population and with a maximum parallax error. Gaia will increase the sample of known white dwarfs tenfold to about 200 000. Gaia will be able to observe thousands of very cool white dwarfs for the first time, which will greatly improve our understanding of these stars and early phases of star formation in our Galaxy.