Characterization and simulation of a CdTe detector for use in PET

The Voxel Imaging PET (VIP) Path nder project got the 4 year European Research Council FP7 grant in 2010 to prove the feasibility of using CdTe detectors in a novel conceptual design of PET scanner. The work presented in this thesis is a part of the VIP project and consists of, on the one hand, the characterization of a CdTe detector in terms of energy resolution and coincidence time resolution and, on the other hand, the simulation of the setup with the single detector in order to extend the results to the full PET scanner. An energy resolution of 0.98% at 511 keV with a bias voltage of 1000 V/mm has been measured at low temperature T=-8 ºC. The coincidence time distribution of two twin detectors has been found to be as low as 6 ns FWHM for events with energies above 500 keV under the same temperature and bias conditions. The measured energy and time resolution values are compatible with similar ndings available in the literature and prove the excellent potential of CdTe for PET applications. This results have been presented in form of a poster contribution at the IEEE NSS/MIC & RTSD 2011 conference in October 2011 in Valencia and at the iWoRID 2012 conference in July 2012 in Coimbra, Portugal. They have been also submitted for publication to "Journal of Instrumentation (JINST)" in September 2012.

Programa de mobilitat segura als centres penitenciaris

Arran de les jornades d’educadors del febrer de 2007 es va constituir un grup de treball d’educadors per crear un programa per a la mobilitat segura. Aquesta proposta va sorgir de la necessitat detectada per la Secretaria de Serveis Penitenciaris, Rehabilitació i Justícia Juvenil (SSPRJJ), com a conseqüència de la reforma del Codi penal. Arran d’aquesta nova legislació s’ha incrementat el nombre d’usuaris que ingressen als serveis penitenciaris per aquests tipus de delictes. El grup d’educadors per a la mobilitat segura crea aquest Programa per donar eines als educadors de presons i als usuaris des de la vessant socioeducativa. En la creació d’aquest programa hem tingut el suport del Servei Català de Trànsit, d’experts de l’equip de Formacció en la matèria de formació de formadors i la Secció d’Educació, Cultura i Esports del Departament de Justícia. Aquest suport s’ha objectivat amb l’aportació de material, llibres, revistes..., així com la supervisió i validació del que tot seguit exposarem. L’estructuració del programa es compon de dos blocs. En una primera part trobem el que són els continguts, és a dir, tot el referent al marc teòric del programa. En aquesta part s’expliquen tots els conceptes bàsics relacionats amb la mobilitat segura. La seva finalitat és donar suport a les sessions del programa. Aquesta part teòrica es divideix en tres apartats: factor humà, via i entorn i vehicle. El factor humà és comú a tots tres, per la qual cosa aquesta divisió és purament analítica i ens serveix per poder esbrinar els factors que influeixen en la mobilitat. En un segon lloc hi trobem totes les dinàmiques i unitats didàctiques per dur a terme la part pràctica del Programa. La metodologia emprada en les pràctiques és la del R-O-A-C que consisteix en: primer, fase de reflexió (R) en què es tracta d’extreure les idees prèvies dels usuaris, el que pensen, saben i creuen al voltant del punt tractat; segon, oferir (O) als usuaris noves experiències perquè incrementin coneixements, millorin habilitats o es replantegin actituds; tercer, aplicar (A) els continguts socioeducatius; quart, conclusió (C) per donar sentit a tots els continguts. Cal destacar la presentació de les dinàmiques en fitxes individuals que faciliten que els professionals puguin treballar i avaluar les sessions individualment segons el seu criteri.

Manual de reciclatge creatiu

Hem volgut elaborar aquest manual i recull informatiu que permeti a qualsevol poder impartir un taller de reciclatge i investigar en la matèria i alhora difondre els treballs que es desenvolupen en els centres amb accions expositives, participació a fires relacionades i de renom, entre d’altres. Aquest any hem començat aquest projecte i hem acomplert els objectius que ens havíem proposat, entre aquests destaquem la participació a la fira de reciclatge Drap-Art que es fa a Barcelona durant el mes de desembre, fira de renom internacional amb presentació prèvia de projecte per poder participar. La importància de gestionar bé els residus que generem en la nostra societat i en especial als nostres centres, implica haver de donar eines als alumnes dels tallers artístics dels centres penitenciaris de Catalunya, conscienciar-los i conscienciar l’entorn de la presó i fer-los servir amb la idea de construcció, d’ideació i creativitat que tot això implica per als interns que hi participen. El reciclatge creatiu és el fruit d’un treball molt més complex que implica una educació i un treball a l’aula per tal de garantir la formació de l’alumne en la sostenibilitat i que d’aquesta manera tingui respecte pel medi ambient, per l’entorn i, per tant, les persones que hi viuen, tant dintre com fora en la vida en llibertat.

Los criterios de valoración tributarios de los precios de transferencia

Aquest treball té com a objectiu l'estudi de la correcta determinació dels preus de transferència, mitjançant els quals una empresa transmet els seus béns materials i actius intangibles o presta serveis a empreses associades. En primer lloc, s'han revisat els fonaments teòrics de l'aplicació dels preus de transferència a nivell internacional establerts per les Directrius de la OCDE i el Fòrum Conjunt sobre Preus de Transferència a la Unió Europea., sempre anomenant les particularitats que atorga la legislació espanyola en la matèria. Seguidament, s'analitzen els diferents mètodes existents per a la determinació dels preus de transferència, il·lustrats amb diversos exemples, i l'anàlisi de comparabilitat que es deurà realitzar al buscar operacions vinculades comparables que permetin la fixació dels preus de transferència. A continuació, es descriuen els procediments administratius que s'utilitzen per intentar reduir i resoldre les controvèrsies que puguin sorgir en aqusta matèria, així com les obligacions de documentació que recauen sobre els contribuents. Finalment, s'exposen algunes reflexions i conclusions sobre els aspectes positius i negatius d'aquesta regulació

Recull de recursos electrònics de codis d'ètica de biblioteques i bibliotecaris

A listing of electronic resources containing ethical or deontological codes. They include references of prominent declarations, professional codes at the national and international levels, thematic guides, and links to resources about the issue, with a calendar of upcoming conferences.

Towards a theory of the credit-risk balance sheet (II). The evolution of its structure

This article has an immediate predecessor, upon which it is based and with which readers must necessarily be familiar: Towards a Theory of the Credit-Risk Balance Sheet (Vallverdú, Somoza and Moya, 2006). The Balance Sheet is conceptualised on the basis of the duality of a credit-based transaction; it deals with its theoretical foundations, providing evidence of a causal credit-risk duality, that is, a true causal relationship; its characteristics, properties and its static and dynamic characteristics are analyzed. This article, which provides a logical continuation to the previous one, studies the evolution of the structure of the Credit-Risk Balance Sheet as a consequence of a business¿s dynamics in the credit area. Given the Credit-Risk Balance Sheet of a company at any given time, it attempts to estimate, by means of sequential analysis, its structural evolution, showing its usefulness in the management and control of credit and risk. To do this, it bases itself, with the necessary adaptations, on the by-now classic works of Palomba and Cutolo. The establishment of the corresponding transformation matrices allows one to move from an initial balance sheet structure to a final, future one, to understand its credit-risk situation trends, as well as to make possible its monitoring and control, basic elements in providing support for risk management.

Optical-geometrical effects on the photoluminescence spectra of Si nanocrystals embedded in SiO2

We demonstrate that thickness, optical constants, and details of the multilayer stack, together with the detection setting, strongly influence the photoluminescence spectra of Si nanocrystals embedded in SiO2. Due to multiple reflections of the visible light against the opaque silicon substrate, an interference pattern is built inside the oxide layer, which is responsible for the modifications in the measured spectra. This interference effect is complicated by the depth dependence of (i) the intensity of the excitation laser and (ii) the concentration of the emitting nanocrystals. These variations can give rise to apparent features in the recorded spectra, such as peak shifts, satellite shoulders, and even splittings, which can be mistaken as intrinsic material features. Thus, they can give rise to an erroneous attribution of optical bands or estimate of the average particle size, while they are only optical-geometrical artifacts. We have analyzed these effects as a function of material composition (Si excess fraction) and thickness, and also evaluated how the geometry of the detection setup affects the measurements. To correct the experimental photoluminescence spectra and extract the true spectral shape of the emission from Si nanocrystals, we have developed an algorithm based on a modulation function, which depends on both the multilayer sequence and the experimental configuration. This procedure can be easily extended to other heterogeneous systems.

Towards a theory of the credit-risk balance sheet (II). The evolution of its structure

This article has an immediate predecessor, upon which it is based and with which readers must necessarily be familiar: Towards a Theory of the Credit-Risk Balance Sheet (Vallverdú, Somoza and Moya, 2006). The Balance Sheet is conceptualised on the basis of the duality of a credit-based transaction; it deals with its theoretical foundations, providing evidence of a causal credit-risk duality, that is, a true causal relationship; its characteristics, properties and its static and dynamic characteristics are analyzed. This article, which provides a logical continuation to the previous one, studies the evolution of the structure of the Credit-Risk Balance Sheet as a consequence of a business¿s dynamics in the credit area. Given the Credit-Risk Balance Sheet of a company at any given time, it attempts to estimate, by means of sequential analysis, its structural evolution, showing its usefulness in the management and control of credit and risk. To do this, it bases itself, with the necessary adaptations, on the by-now classic works of Palomba and Cutolo. The establishment of the corresponding transformation matrices allows one to move from an initial balance sheet structure to a final, future one, to understand its credit-risk situation trends, as well as to make possible its monitoring and control, basic elements in providing support for risk management.

Structure and energetics of mixed 4He-3He drops

Using a finite-range density functional, we have investigated the energetics and structural features of mixed helium clusters. The possibility of doping the cluster with a molecule of sulfur hexafluoride is also considered. It is seen that the repulsion introduced by the impurity strongly modifies the properties of the smallest drops. Although only a qualitative comparison is possible, the gross features displayed by our calculations are in agreement with recent experimental findings.

Twist mode in atomic Fermi gases

The quantum-kinetic energy of a finite number of trapped fermionic atoms provides a restoring force for shear motion due to a distortion of the momentum distribution. In analogy to the twist mode of nuclear physics, it is proposed that counter rotating the upper and lower hemisphere of a spherical atomic cloud yields a finite-frequency mode closely related to transverse zero sound waves in bulk Fermi liquids.

Pairing with polarization effects in low-density neutron matter

We study the properties of the 1S0 pairing gap in low-density neutron matter. Different corrections to the lowest-order scattering length approximation are explored, resulting in a strong suppression with respect to the BCS result.

Spin polarized neutron matter and magnetic susceptibility within the Brueckner-Hartree-Fock approximation

The Brueckner-Hartree-Fock formalism is applied to study spin polarized neutron matter properties. Results of the total energy per particle as a function of the spin polarization and density are presented for two modern realistic nucleon-nucleon interactions, Nijmegen II and Reid93. We find that the dependence of the energy on the spin polarization is practically parabolic in the full range of polarizations. The magnetic susceptibility of the system is computed. Our results show no indication of a ferromagnetic transition which becomes even more difficult as the density increases.

Antikaon potential in hot and dense matter

The antikaon optical potential in hot and dense nuclear matter is studied within the framework of a coupled-channel self-consistent calculation taking, as bare meson-baryon interaction, the meson-exchange potential of the Jlich group. Typical conditions found in heavy-ion collisions at GSI are explored. As in the case of zero temperature, the angular momentum components larger than L=0 contribute significantly to the finite temperature antikaon optical potential at finite momentum. It is found that the particular treatment of the medium effects has a strong influence on the behavior of the antikaon potential with temperature. Our self-consistent model, in which antikaons and pions are dressed in the medium, gives a moderately temperature dependent antikaon potential which remains attractive at GSI temperatures, contrary to what one finds if only nuclear Pauli blocking effects are included.