The loop group and the cobar construction

"Vegeu el resum a l'inici del document del fitxer adjunt."

Singular integrals on Ahlfors-David regular subsets of the Heisenberg group

"Vegeu el resum a l'inici del document del fitxer adjunt."

A numerical algorithm for finding solutions of a generalized Nash equilibrium problem

A family of nonempty closed convex sets is built by using the data of the Generalized Nash equilibrium problem (GNEP). The sets are selected iteratively such that the intersection of the selected sets contains solutions of the GNEP. The algorithm introduced by Iusem-Sosa (2003) is adapted to obtain solutions of the GNEP. Finally some numerical experiments are given to illustrate the numerical behavior of the algorithm.

Disseny d'un mètode de valoració d'itineraris d'educació ambiental i aplicació a l'àmbit Parc Natural de l'Alt Pirineu - Alt Urgell

El Parc Natural de l’Alt Pirineu (PNAP) està creant una xarxa d’itineraris d’educació ambiental amb l’objectiu de divulgar els valors del parc i conscienciar els seus visitants sobre la importància de conservar el medi ambient. El desenvolupament de mètodes de valoració de l’aptitud de potencials itineraris d’educació ambiental pot servir per crear eines de gestió molt útils a l’hora d’ampliar aquesta xarxa de senders. Per aquest motiu, un grup anterior de la llicenciatura de Ciències Ambientals va desenvolupar el preprotocol Neret, que permet obtenir una puntuació numèrica per a un itinerari, responent a una sèrie de preguntes senzilles. En el present projecte, s’ha aplicat el protocol anterior a tres itineraris de muntanya per tal d’estudiar-ne el funcionament en un tipus d’itinerari diferent dels de fons de vall, on va ser dissenyat. L’anàlisi del preprotocol s’ha efectuat mitjançant una matriu DAFO, a partir de la qual s’han proposat una sèrie d’estratègies de millora i, a partir d’aquestes, s’ha desenvolupat un nou mètode de valoració. Els principals aspectes negatius del preprotocol són la seva manca de flexibilitat, la sobrevaloració dels criteris relacionats amb la dificultat del recorregut, la manca de detall en l’anàlisi del potencial interpretatiu dels itineraris a més del poc pes que té aquest criteri en la puntuació global i, finalment, l’absència d’un criteri que valori els potencials impactes que es podrien derivar de l’ús de l’itinerari. Aquestes mancances s’han mirat de corregir al mètode de valoració dissenyat en el present projecte mitjançant les següents aportacions: una estructura transversal dividida en quatre factors avaluats per separat, sense criteris de valoració excloents i amb una ponderació final dels quatre principals criteris modificable segons els objectius dels gestors; una valoració més detallada dels continguts de l’itinerari, i finalment, la inclusió d’un nou criteri que considera la vulnerabilitat del medi a qualsevol tipus d’impacte.

An irreducibility criterion for group representations, with arithmetic applications

We prove a criterion for the irreducibility of an integral group representation p over the fraction field of a noetherian domain R in terms of suitably defined reductions of p at prime ideals of R. As applications, we give irreducibility results for universal deformations of residual representations, with a special attention to universal deformations of residual Galois representations associated with modular forms of weight at least 2.

A numerical solver for a nonlinear Fokker-Planck equation representation of neuronal network dynamics

To describe the collective behavior of large ensembles of neurons in neuronal network, a kinetic theory description was developed in [13, 12], where a macroscopic representation of the network dynamics was directly derived from the microscopic dynamics of individual neurons, which are modeled by conductance-based, linear, integrate-and-fire point neurons. A diffusion approximation then led to a nonlinear Fokker-Planck equation for the probability density function of neuronal membrane potentials and synaptic conductances. In this work, we propose a deterministic numerical scheme for a Fokker-Planck model of an excitatory-only network. Our numerical solver allows us to obtain the time evolution of probability distribution functions, and thus, the evolution of all possible macroscopic quantities that are given by suitable moments of the probability density function. We show that this deterministic scheme is capable of capturing the bistability of stationary states observed in Monte Carlo simulations. Moreover, the transient behavior of the firing rates computed from the Fokker-Planck equation is analyzed in this bistable situation, where a bifurcation scenario, of asynchronous convergence towards stationary states, periodic synchronous solutions or damped oscillatory convergence towards stationary states, can be uncovered by increasing the strength of the excitatory coupling. Finally, the computation of moments of the probability distribution allows us to validate the applicability of a moment closure assumption used in [13] to further simplify the kinetic theory.

Group strategy-proof social choice functions with binary ranges and arbitrary domains: characterization results

We define different concepts of group strategy-proofness for social choice functions. We discuss the connections between the defined concepts under different assumptions on their domains of definition. We characterize the social choice functions that satisfy each one of them and whose ranges consist of two alternatives, in terms of two types of basic properties.

Sistema de votació electrònica sobre corbes el·líptques amb mescla de vots mitjançant Random Group Full Checking

L'objectiu del treball és dissenyar i implementar un sistema de simulació de votació electrònica, emprant una adaptació sobre corbes el·líptiques del criptosistema ElGamal, per tal d'estudiar-ne la viabilitat, centrant l'atenció en temes de seguretat, especialment en el procés de mescla de vots per tal de desvincular un vot de la persona que l'ha emès.

Internal test sets studies in a group of antimalarials

Topological indices have been applied to build QSAR models for a set of 20 antimalarial cyclic peroxy cetals. In order to evaluate the reliability of the proposed linear models leave-n-out and Internal Test Sets (ITS) approaches have been considered. The proposed procedure resulted in a robust and consensued prediction equation and here it is shown why it is superior to the employed standard cross-validation algorithms involving multilinear regression models

Methodology for studying the numerical speed of sound in finite differences schemes

The space and time discretization inherent to all FDTD schemesintroduce non-physical dispersion errors, i.e. deviations ofthe speed of sound from the theoretical value predicted bythe governing Euler differential equations. A generalmethodologyfor computing this dispersion error via straightforwardnumerical simulations of the FDTD schemes is presented.The method is shown to provide remarkable accuraciesof the order of 1/1000 in a wide variety of twodimensionalfinite difference schemes.

Genetic characterization of the ABO blood group in Neandertals

Background: The high polymorphism rate in the human ABO blood group gene seems to be related to susceptibility to different pathogens. It has been estimated that all genetic variation underlying the human ABO alleles appeared along the human lineage, after the divergence from the chimpanzee lineage. A paleogenetic analysis of the ABO blood group gene in Neandertals allows us to directly test for the presence of the ABO alleles in these extinct humans. Results: We have analysed two male Neandertals that were retrieved under controlled conditions at the El Sidron site in Asturias (Spain) and that appeared to be almost free of modern human DNA contamination. We find a human specific diagnostic deletion for blood group O (O01 haplotype) in both Neandertal individuals. Conclusion: These results suggest that the genetic change responsible for the O blood group in humans predates the human and Neandertal divergence. A potential selective event associated with the emergence of the O allele may have therefore occurred after humans separated from their common ancestor with chimpanzees and before the human-Neandertal population divergence.

CLFP intrinsic constraints-based group management of blended learning situations

When applying a Collaborative Learning Flow Pattern (CLFP) to structure sequences of activities in real contexts, one of the tasks is to organize groups of students according to the constraints imposed by the pattern. Sometimes,unexpected events occurring at runtime force this pre-defined distribution to be changed. In such situations, an adjustment of the group structures to be adapted to the new context is needed. If the collaborative pattern is complex, this group redefinitionmight be difficult and time consuming to be carried out in real time. In this context, technology can help on notifying the teacher which incompatibilitiesbetween the actual context and the constraints imposed by the pattern. This chapter presents a flexible solution for supporting teachers in the group organization profiting from the intrinsic constraints defined by a CLFPs codified in IMS Learning Design. A prototype of a web-based tool for the TAPPS and Jigsaw CLFPs and the preliminary results of a controlled user study are alsopresented as a first step towards flexible technological systems to support grouping tasks in this context.

Why do workers leave unions? - group differences in a Spanish Union Federation

This study analyses the characteristics of members leaving a Spanishunion federation – Catalonia branch of Workers’ Commissions(CCOO-Catalonia), together with their reasons for leaving using avariety of data sources. Our findings indicate that higher union attritionamong members in instable employment (i.e. casual employment andlow seniority). In general, union leavers confirm that their job situationis an important reason for leaving the union. We therefore concludethat efforts made by the union to retain members in vulnerable labormarket positions are important in reducing high rates of union attritionin Spain.