PHYSICS

Author: Valle Delgado Juan José.
Year: 2003.
University: GRANADA.
Place of defense: Facultad de Ciencias.
Place of preparation: Facultad de Ciencias.

Summary: Since the Astrophysics (whose object of study are the stars, galaxies and constellations) to the Particle Physics and High Energy (where electrons, protons, neutrons and other elementary particles are the target of investigations), the physics can be divided into very different fields. One of those areas is the Colloidal Physics, responsible for the study of particles that are midway between the microscopic and the macroscopic world, with sizes ranging from a few nanometers and several microns. The dispersions of these particles in a medium are called colloids. In the case where the means of dispersion is a liquid (usually water) speaks of colloidal dispersion or dissolution. Paints, lacquers, aerosols, food dispersions (mayonnaise, butter, ice cream, milk, etc..), Inks, biological fluids such as blood, pharmaceuticals and cosmetics are just some examples of colloidal dispersions. The study!

Author: LARIO DE LLANO ROBERTO.
Year: 2004.
University: COMPLUTENSE DE MADRID.
Place of defense: FACULTAD DE CIENCIAS FÍSICAS.
Place of preparation: FACULTAD DE CIENCIAS FÍSICAS.

Summary: This thesis focuses on the study of algorithms for real-time display of irregular land that big dimensiones.Los challenges posed by this type of display from a computational point of view necessitates the use of algorithms simplificación.Para so we opted for models represetnación jerárquco to reduce the complexity of the field and in turn ensure the quality of the visual, making it possible for different parts of the field visible to the observer can appear at different levels of detalle.La choice of irregular mesh generation has increased complexity the proposed algorithms, however, has provided great benefits, as it allows an approximate surface for a given accuracy with fewer triangles that the regular schedule for allowing more number of samples in areas that are rugged and less on the flat areas .

Author: Campanario Pallás Francisco.
Year: 2004.
University: VALENCIA.
Place of defense: Ciencias Físicas.
Place of preparation: Departamento de Física Teórica, Universidad de Valencia.

Summary: In decay processes of B mesons de so-called "heavy to light currents" play an important role, for example in the determination of matrix elements of the CKM mixing matrix. The present Thesis investigates various aspects of the strong interaction of the quarks participating in the heavy to light currents. The theory of the strong interaction is Quantum Chromodynamics, which is treated in perturbation theory. After a short introduction to the relevant effective theories, which are derived from QCD, some new results are presented. First the asymptotic behaviour of the perturbative series is investigated, and the second result are proofs of factorization theorems which are used to separate the perturbative from the non-perturbative contributions. Finally, the symmtries of the effective field theories are used to find relations between the non-perturbative matrix elements involved in "heavy to light currents".

Author: SAN JOSÉ MARTÍN PABLO.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: INSTITUTO DE CIENCIA DE MATERIALES DE MADRID CSIC..

Summary: 1-Introduction concepts intended to be covered by the work revolve around the electrostatic interactions and exchanges in nano-granos metallic granular networks and their effect on transportation. A new technique based on the description of superconductivity through the action of a quantum rotor, and the same family who techniques bosons slaves was used to describe the coexistence of the Coulomb blockade and the Kondo effect in metallic nanostructures. It realizaró an analysis of the dependence of these effects with the spectral details of the nanoestructura, and the resulting physical consequences that are in transport through granular systems within the "Theory" field dynamic environment "(DMFT), especially in the transition metal-aislante of Mott. 2 - The description of the Coulomb Blockade by the rotor quantum. We made a careful review of the description of the Coulomb blockade in terms of the dynamics effectiva of phase system nanostructures normal , as a particular case of the techniques developed at the beginning of the eighties to descibir microscopic dynamics of phase superconducting Josephson in the joints. This serves as a technical introduction to the field. was discuteron concepts Coulomb blockade, cotunneling, conductance and energy load renormalizada in the context of formalism. 3 - The tjescription of Coulomb Blockade and the Kondo effect by the method of the rotor slave. A technique similar to that of slaves but bosons based on the method of the rotor is quantum used to describe the coexistence of both the Kondo effect and Coulomb blockade in nanostructures. nanostructures is capable of dealing with a chaotic spectrum arbitrary. Effective action involves fermions and the rotor and was treated in a "rapprochement without crossing" ( Non-crossing approximation-NCA) followed by an 'approximation esféica. " The resulting model captures semí-cuantitativamente the main phenomena of these systems. A comparison was made with other techniques bosons slaves. We discussed the effect on the spectrum of Coulomb blockade and the Kondo effect, and transport. We identified specific schemes (Kondo multilevel, transition to reverse Kondo Coulomb blockade, and Kondo in two stages). It outlined the phase diagram of a nanoestructura generic. 4-Lock spin magnetic grains. A generalization of the method of quantum rotor was proposed to describe systems with interactions exchange JS "2, where S is the total spin of the system. Carried out a qualitative discussion and Monte Carlo simulations for a superconducting grains in various regimes. Were identified effect of the amount J / E_C on fluctuations in loading and transport. 5 - The transition metal-aislante in granular systems were used methods of chapter 2 and 3 in the context of DMFT to analyze the characteristics of the transition from Mott in granular systems and the effect of the spectral properties of the grains on the transition. also scrutinized transitions caused by effects excitónicos and outlined the phase diagram in the presence of complex spectral properties.

Author: HARO PÉREZ CATALINA ESTHER.
Year: 2004.
University: GRANADA.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Author: GODOY RUBIO RAFAEL.
Year: 2004.
University: GRANADA.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: This thesis presents some progress made in the methods of differences in the time domain unconditionally stable to be applied to solving the Maxwell equations. First, it conducts a review of the FDTD method classic Yee, paying particular attention to their convergence, cosnistencia and stability. The following are the foundations of the new method unconditionally stable known as Implicit Method of Directorates Alternantes (ADI-FDTD), based on the scheme Crank-nicolson (CN-FSTAD). It demonstrates and shows numerically, that the new method provides stability unconditional and is not limited, unlike the classic FDTD for compliance with the condition Courant-Friedrichs-Lewy (CFL). Thus, it will significantly reduce the execution time delas computational simulations performed. Moreover, it carries out the systematic construction method ADI-FDTD starting a fault scheme Crank-Nicolson and extends to dispersive media, PML conditions absorbent, and so on. There will always be a study of the errors of method ADI-FDTD (dispersion, truincamiento) and the constraints they put into the election dela discretization temporary use. It also proposed a new formulation does not split the PML-Bérenger, the reformulation of PML in coordinates widespread and as uniaxial scheme Crank-Nicolson upset with the aim of ensuring stability unconditional. Finally, a tool hybrida (ADI-FDTD-MoMTD), which includes the method of moments in the time domain (MoMTD) and that utilliza for studying the interaction of electromagnetic waves with transitional porous bodies, in particular, for non-destructive detection systems such as ground penetrating radar (GPR) or systems breast tumors.

Author: MAIRA VIDAL ARANZAZU.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: INSTITUTO DE ESTRUCTURA DE LA MATERIA.

Summary: In order to investigate the collective excitation in simple liquids and its relationship to the movements of individual atoms was studied potassium melted at a temperature close to the merger and the other over a hundred degrees higher. We used it for various neutron scattering techniques and molecular dynamics simulations. Analysis of the spectra showed some incoherent diffusion coefficients lower than predicted by the model Enskog, moreover spectra can be described in the model modes Trailers interpreting the delay in the circulation as due to acoplo of diffusion the collective excitation. Analysis of the spectra consistent shows the existence of two contributions to its component cuasielástica; being one of them, by their conduct, interference phenomena of an atom in motion stochastic that interacts with its neighbors. The origin of the second is yet unknown, although it is believed that the free electrons in the metal may be playing an important role in it. The inelastic scattering spectra show turn excitation frequencies to non-zero values to Q as great as 0.8Qp the two temperatures studied, being Qp the value of Q in which the factor structure presents its first maximum. Such excitation presented positive dispersion, namely approaching the limit hydrodynamic frequency corresponding to the propagation speeds of excitement significantly greater than the speed of sound in the material, this effect being more pronounced near the merger. This phenomenon, common in the alkali metals, it is probably due to the response to the disturbance of the liquid is elastic, as suggested by the fact that close to the melting curves dispersion of liquid alkali metals are similar to those of its crystals. Besides the element of tensor elastic modulus C11 (which is related to the longitudinal component of the stress tensor) calculated for the liquid potassium varies little in the merger, indicating that differences between the glass and liquid short distances are very small. Therefore, the local structure of the liquid and glass are similar and the excitation occurring in the former can be understood based on the oscillation of small groups of atoms. In the second part of the thesis presents the research conducted at the miscroscópicas mixtures with behavior reentrante, using different techniques for neutron scattering, nuclear magnetic resonance and molecular dynamics simulations. As a result of these investigations were observed correlation lengths significantly higher in mixtures reentrant compared with mixtures of different percentage by weight of the solute and behavior miscible This result is interesting for the fact that such interference continue being marked at distances sufficiently separated the transition. Moreover rotational diffusion coefficients obtained from dispersion cuasielástica neutron and nuclear magnetic resonance show the existence of directional forces between the molecules of the solute and solvent before and after the transition phase at low temperature, that fact contradicts the widely accepted explanation of Hirschfelder about the origin of this transition. The study of one of the pure components of the mixtures showed an anomalous behavior of their coefficients of translational and rotational diffusion with increasing pressure, decreasing linearly in the beginning, as expected, then stabilized later (in the range of 150 bars) and continuing its decline with different slope to the original. These results, which were reproduced with a simulation of molecular dynamics, have been attributed to a change in packaging of the molecules that make up the liquid and interpreted as a liquid-liquid transition. It is important to underline that this anomaly will produce 8 ea p 2db resión where the mixture critical reentrante of that component in heavy water presents a critical double.

Author: GALISTEO LOPEZ JUAN FRANCISCO.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: FACULTAD DE CIENCIAS.AUTONOMA DE MADRID.
Place of preparation: INSTITUTO DE CIENCIA DE MATERIALES DE MADRID.

Summary: This dissertation deals with the manufacture and characterization (optical and structural) crystal fotónicos based ópalos artificial. The contents of the thesis is as follows: Chapter 1: Introduction to the crystals fotónicos In this chapter provides a general introduction to the field of crystals fotónicos. It includes the methods of theoretical modeling, manufacturing methods, optical properties and applications. Chapter 2: Manufacture and structural characterization of ópalos artificial After describing qualitatively the growth process of ópalos artificial deposition by vertical are those experimental conditions under which the samples were obtained better quality optics. Finally, it presents a structural study of the crystals grown. Chapter 3: Survey optical pseudogap-L in ópalos of laminated thin Using techniques reflection spectroscopy and transmission carried out a study of the optical properties of ópalos grown previously. This study was carried out in the spectral region of pseudogap-L. First carried out a study of the dependence of the spectral response of the samples with its size and the substrate on which they are grown. At the same determining the minimum thickness for which the optical response of the samples does not present effects of finitude. Here are studying the effect of disorder on the optical properties of the samples. It is found that the spectral dependence of the diffuse intensity generated in the crystal as a result of the presence of defects is determined by the relationship of dispersion calculated. Finally, it examines the response optic along high-symmetry directions on the glass and compares the results with theoretical calculations of the dispersion relation. Chapter 4: Optical Properties of ópalos artificial in the region of high-energy We present a detailed study of the optical properties in the region of high energy for samples floods previously. First is verified that the spectral response is scalable with the parameter network and also does not depend on the size of the crystal. Here are studying the origin of the bands of energy in this spectral region, we found that can be considered as overlapping relationships dispersion associated with half homogeneous and a network of diffraction 2D. The influence of different types of energy bands in the propagation of light through the sample is studied by diffraction experiments. Finally, it compares the response to the ratio of optical scattering calculated, found that the former is determined mainly by the shape of those bands associated with a homogeneous half. Chapter 5: Interferometry with white light of ópalos in thin layer This chapter uses the technique with white light interferometry to study the gap that takes light to spread in a thin layer artificial opal. Measurements are carried out in a amplo spectral range which includes the regions of high and low energy. From the stage draws a refractive index requirement (assuming previously behavior half a homogeneous) and the group velocity. The results are compared with the dispersion relation calculated. Chapter 6: Unit of the optical response of ópalos artificial polarization is presented with a demonstration pilot dependence on the optical response of ópalos artificial polarization. The study is conducted in an environment Spectral pseudogap-L. It is found that the symmetry properties of the bands accessible determine acoplo with different polarization of incident light. Chapter 7: We studied the optical properties of monodominios of ópalos artificial volume. This will employ beams focused on regions of 10 microns. It determines the presence of a structure with mosaic whose domains have a normal dispersion  ± 3Âş. Specular reflection is measured for different angles and compares the results with a ratio of scattering calculated.

Author: PASCUAL SALVADOR ANTONIO.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: UNIVERSIDAD AUTONOMA DE MADRID.
Place of preparation: UNIVERSIDAD AUTONOMA DE MADRID.

Summary: The pyrite is a mineral semiconductor belonging to the group sulphides whose chemical formula is FeS2. Formed by chemicals abundant and low cost, this material has been widely studied because of the interest generated by their electrical properties, which make the pyrite in thin-film material potentially useful in applications and photovoltaic power plants. However, the yields of these materials do not reach the expected values despite its good properties. These low yields are due to the lack of knowledge in their electrical transport properties, which are directly related to its formation mechanism. There are only two models for the qualitative training of thin films of pyrite [1.2], models that prove to be contradictory to one another. It is imperative, therefore, in-depth knowledge of how to form thin films of FeS2 to try to overcome the limitations of this material in photovoltaic applications and power plants. This thesis investigates the formation of thin films of FeS2 by sulphidation film Faith and, since the factors that limit the performance of these materials are directly related to lack of knowledge in its transport properties, has been chosen consider training through the evolution in situ (during training) in two of its major properties of transport: electrical resistance (R) and Seebeck coefficient (S). The experimental system developed has led to record the evolving RyS of thin films of Faith during his sulphidation until its transformation into movies FeS2. It has been observed that these developments are not continuous, but presents a number of behavioral changes that appear regularly and are associated with different physical and chemical processes separate. We have arrested the formation processes of some films at different moments of curves, making it possible, through the characterization of in situ and ex situ, analyze and evaluate changes in the films of Faith until his complete transformation into FeS2 . It has been shown that the formation is a process that takes place through five reacciones-transformaciones different: 1. Sulfuración Fe precursor to form hexagonal pyrrhotite. 2. Transformation crystallographic part of the hexagonal pyrrhotite to form pyrrhotite ortorrómbica. 3. Sulfuración of pyrrhotite ortorrómbica to form FeS2. 4. Sulfuración of hexagonal pyrrhotite to form FeS2. 5. Internal Transformation of FeS2 formed. We have quantitatively analyzed each of the proposed changes and has been a model molecular complete training. This analysis has enabled present for the first time a mechanism complete and quantitative formation of thin films of FeS2 by sulphidation thin films of Faith. It has analyzed the impact of experimental variables on the formation, which has improved understanding and consolidating the results obtained by other authors, results hitherto seemed contradictory to one another. The mechanism of formation of thin films of FeS2 proposed in this thesis is a comprehensive and quantitative mechanism, which has enabled understand various issues so far remained misunderstood in this material, and that has laid the foundation of knowledge necessary to implement the electrical properties of the FeS2 and able to develop photovoltaic devices and thermoelectric low cost based on this material that can compete with the materials, more expensive and more polluting, which are used today in such devices. [1] G. Pimenta W. Kautek, Thin Solid Films 219 (1992) 37. [2] J. R. Ares, "Mechanism of training and type of conductivity in thin films of pyrite," Ph.D. Thesis, Universidad Autonoma de Madrid, 2002.

Author: CONDE GARCIA JORGE.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS. INIVERSIDAD AUTONOMA DE MADRID.

Author: HERNANDEZ JUAREZ BEATRIZ.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: INSTITUTO DE CIENCIA DE MATERIALES DE MADRID.

Author: CORTÉS DÍAZ JESÚS MARÍA.
Year: 2004.
University: GRANADA.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: In this thesis is studied using computational and analytical techniques of no-equilibrio how it affects the different dynamics to incorporate synapses more or less realistic in the emerging and macroscopic properties of neural networks atractoras. In particular, research has been the emergence of associative memory, the stability of different atractores the dynamics in the presence of external stimulation, and the existence of chaotic trajectories between different atractores. It has been studied three different levels of complexity in the dynamics associated with the variables that describe the state of the synapse: 1, has been considered a dynamic synapses deterministic and based on a phenomenological model that allows real replicate experiments. This incorporates dynamic effects of depression and facilitation synaptic. Acoplada this dynamic neurons evolve in a stochastic. The effect of facilitation is to reduce significantly the critical capacity of the network, however, it can respond more quickly to changing stimuli. 2 - The synapses are subject to the action of a disturbance or noise stochastic fast depends on the activity presinaptica. Neurons evolve estocásticamente in the presence of a stationary distribution of noise fast. This induces instability of atractores which improves the response of the network against external stimuli. 3-Finally, it has developed an artificial model where the intensities have synaptic stochastic controlled by a parameter temperature. That dynamic is coupled to the dynamics in neurons is also stochastic. The dynamics of this model allows to detect correlations between the patterns learned, which makes it useful for problems of categorization and classification of memories.

Author: BADOSA FRANCH JORDI.
Year: 2004.
University: GIRONA.
Place of defense: ESCUELA POLITÉCNICA.
Place of preparation: FACULTAD DE CIENCIAS.

Author: BADOSA FRANCH JORDI.
Year: 2004.
University: GIRONA.
Place of defense: ESCUELA POLITÉCNICA.
Place of preparation: FACULTAD DE CIENCIAS.

Author: PÉREZ MORENO JUAN PEDRO.
Year: 2004.
University: SEVILLA.
Place of defense: UNIVERSIDAD DE SEVILLA.
Place of preparation: UNIVERSIDAD DE SEVILLA.

Summary: In some factories of the Industrial Pole of Huelva occurs for wet phosphoric acid from the phosphate rock or phosphate rock. This rock may contain relatively high concentrations of uranium in respect of a typical soil. In this paper we studied the flow of natural radionuclides in the industrial process manufacturing phosphoric acid and also has assessed the radiological impact on Environment and workers that this industry can produce. For the development of this work we have undertaken, and an overall calibration equipment gamma spectrometry, which takes into account the composition, bulk density and quantity of different samples to be analyzed in the energy range of interest.

Author: Chavarría Díaz Miguel.
Year: 2005.
University: VALENCIA.
Place of defense: Escola Tècnica Superior d'Enginyeria.
Place of preparation: Escola Tècnica Superior d'Enginyeria.

Summary: The Integration of Information Systems in Health, under the new concept of Enterprise Integration of Health, is a crucial part in scientific and technical research in information systems for diagnostic radiology, since it allows modeling architectures and general interoperability between different systems that acquire, treat, store and distribute radiological information as input to electronic medical records of patients. Thus, thanks to this disciplinary framework will be possible to obtain practical outcomes on particular models and architectures that enable the improvement of the integration of subsystems, the interoperability between them and the technical certification of the underlying technologies. The overall objective of this thesis is to develop a particular architecture for the integration and interoperability of information systems that are used in hospital radiology services. From the general to the more specific, such systems are as follows: Hospital Information System (HIS), Radiological Information System (RIS), Image Management System (PACS), acquisition systems and / or image generation or modalities, and visualization systems specific for the diagnosis. In the course of the investigation leading to this thesis, it has obtained evidence that the models and architectures general Integration Business Health (IHE), defined as the integration of all functions and tasks in health can adapted more specific models and architectures in the field of radiology, as well as allowing increased wealth expressive of these models, functional for the unification of the patient's medical history, starting with the promotion of the uniqueness of identifying patients . From the standpoint of Integrating Health Organizations, the main contribution of this dissertation is the development of an architecture for integrating the service Radiodiagnostic Adult University Hospital "Faith". In this sense, the specific contributions were as follows:-A model processes Radiodiagnostic Service Adult which has allowed formalize the functional characterization of the same, identifying the mechanisms or resources, controls, inputs and outputs. - A system of indicators for measuring the degree of integration of the subsystems of information involved in the management of the Radiodiagnostic Service for Adults. - An architecture for the integration of the subsystems of information involved in the management of the Radiodiagnostic Service Adult according to the IHE approach. From the standpoint of discipline Radiology Digital, the main contribution is the development of a body of terminology IHE adapted to Spanish and the area of Digital Radiology. That body terminology have been raised equivalency designations Profiles, Actors and Transactions IHE, originally in English, and in addition, the definitions have been adapted as customary uses in Radiodiagnostic.

Author: SANZ GONZALEZ OSCAR.
Year: 2005.
University: AUTÓNOMA DE MADRID.
Place of defense: EDIFICIO DE BIOLOGICAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: The objective of this work was the preparation of thin films of oxide glasses of heavy metals (HMO) with nonlinear optical properties and luminescent improved with regard to the white line, which would make them likely to be considered in the development of devices both optical switching and gain waveguide. That goal has required study and understand the mechanisms of growth of the blades, analyze the influence of growing conditions have in their structural properties and finally, the latter correlated with the optical properties and luminescent. The results have demonstrated the feasibility of pulsed laser deposition to synthesize glass thin films of oxides of heavy metals and achieve compositions in thin layer with heavy metal content on high, which is unattainable with techniques of mass production of glass. "There is a significant incorporation of O2 in the atmosphere to thin films for working pressures greater than 10-2 mbar, which favors the formation of the network and allows vitreous produce transparent sheets. Way blades synthesized in vacuum (5 10 - 6 mbar) have only a 50% oxygen with respect to the white line, while the use of a pressure of 9 10-2 mbar O2 increases that content up to 84%. "Increasing the density of laser energy (E ) causes an increase in the density of the film, which has been linked to an increase in kinetic energy of the species in the plasma. It has also been shown that there is an optimal E, 2 J/cm2 for a distance blanco-sustrato of 3 cm, for the production of wafers with good surface morphology. "It has reached a refractive index of n = 2.35, which is a value much greater than the maximum achievable glass massive system PbO-Nb2O5-GeO2." Has been identified for the first time the value of coefficient (3 ) corresponding to a thin layer glass in HMOs, with a maximum value of (3) 10-11 esu, which represents more than 103 times that of SiO2 and 60 times the mass measured for whites transparent. "To demonstrate that it is possible nanoestructurar glasses HMO in thin layer of Er ions distributed in layers separated by an interval of a few nm. In particular, it was found that increasing the concentration of ions erbio implies an increase of the intensity of luminescence at 1.53 m and a decrease in the lifetime average () in situ doped wafers grown by as doped situ. This behavior has been associated with processes of non-radiative energy transfer between ions. Also, the increase in the separation between layers in the case of Er doped spot causes an increase in the intensity of the luminescent plates while remaining constant. This behavior has been associated with non-radiative processes, the likelihood increases when the separation between layers is less than 5 nm because in this case the local Er concentration increases significantly. Lastly, it has also seen how it decreases with increasing concentration of heavy ions in the strips. This decrease is due to the influence the refractive index on the sheets. "The attack occurred at the crucibles involves the incorporation of contaminants such as Au or Pt coloring glass obtained, while in other cases (crucible of SiO2) is modified greatly the composition of glass heading for joining it. Secondly, the use of high temperatures, higher than 900Â ° C, favors termorreducción of Bi3 + Bi0 and the appearance of droplets in the glass giving it a brown color virtually opaque. It has been shown that the use of oxidizing agents, especially CeO2, transparency returns to the glass. "There were synthesized using PLD thin films of bismuth oxide glasses using the parameters selected for optimal synthesis system PbO-Nb2O5-GeO2 and, in particular, it has studied the effect of substitution of GeO2 by Bi2O3 in properties optics. was reached shift visible from the edge of absorc 8 ion and 3a5 increase in the indices of refraction linear and nonlinear, which confirms the decisive role that heavy metals, particularly its high polarizabilidad, have in the properties optical glass HMOs that have been the subject of this work.

Author: Flix Molina José.
Year: 2005.
University: AUTÓNOMA DE BARCELONA.
Place of defense: IFAE - Departamento de Física.
Place of preparation: IFAE - Universidad Autònoma de Barcelona.

Summary: Knowledge of the nature of dark matter is one of the key problems still unresolved in Cosmology and your quest is a prime objective in science today. This matter has not been observed directly, and has only been able to deduct from their gravity effects. The observational evidence shows that dark matter accounts for 27% of the entire mass of the universe, compared with only 3% of the field visible or observable. The rest, according to current cosmological models, consists of dark energy and matter. In recent years, several candidates have been proposed to form part of this dark matter. It is now speculating with some kind of heavy particle that had survived the âGran Explosiónâ, ie it was stable enough to not have collapsed so far. Of the known particles, there is no satisfying these requirements. However, in recent decades, have developed new theories of particle physics, the so-called theories Supersimétricas, also in a unified manner to explain the nature and characteristics of all known particles and comply with the experimental results obtained in large accelerator, predict the existence of a new type of particle among which there is one that could be a very plausible candidate: âneutralinoâ (other than âneutrinoâ, particle that has also been a candidate for dark matter). For now, there is no direct experimental evidence for the existence of these new particles, but the theory predicts that can be detected at the Large Hadron Collider (LHC), the large proton accelerator that is built at CERN in Geneva, and that begin to operate in 2007. The Theories Supersimétricas predict that, in high concentrations, neutralinos may interact among themselves, aniquilándose and resulting in very high energy radiation (gamma rays), which could be detected in an indirect way on Earth. The cosmological simulations predict that these neutralinos have evolved and formed galaxies in the universe that we can not see, but ânotar its presenciaâ due to the gravitational field they generate. MAGIC is a Cherenkov telescope, which detects visible light produced by gamma radiation to penetrate the atmosphere. With 17 meters in diameter, is the largest telescope of its kind and more sophisticated in the world, at this time, and has the characteristics necessary to detect the signal from the annihilation of neutralinos. The telescope, installed in the Observatory Roque de los Muchachos, the region has been observed from the center of our galaxy, where presumably signal annihilation of neutralinos is very bright. The thesis takes a theoretical and phenomenological aspect, which explores in detail the type of signal expected for the heart of our galáxia. It continues with a description of the telescope and technical tasks in which the author of the thesis has been involved. The final part of the thesis is devoted to the analysis of the data obtained, as well as their interpretation in a frame of dark matter supersimétrica. The observed signal is hardly interpretable in this framework. Several alternatives to explain the origin of this radiation are detailed. For today, the source of that radiation is being investigated and there is still no plausible explanation.

Author: Varela Rizo Oscar.
Year: 2005.
University: VALENCIA.
Place of defense: Facultad de Física.
Place of preparation: Facultad de Física.

Summary: Eleven-dimensional M Theory is conjectured to contain and unify quantum gravity and the rest of fundamental interactions. Despite its current lack of a precise formulation, hints and information about M Theory can be retrieved from its low energy limit, eleven-dimensional supergravity. This thesis aims to make progress towards the understanding of the symmetries and structure of M Theory from the study of eleven dimensional supergravity. Two important questions in M Theory, yet to be solved, are 1) how many supersymmetries can an M Theory background preserve and 2) what is the symmetry of M Theory. Both questions can be addressed at the D=11 supergravity level. The former question can be addressed for purely bosonic solutions by means of generalized holonomy, namely, the holonomy of the supersymmetric connection defining the supersymmetry variation of the gravitino. We shall discuss the role of generalized holonomy with this regard and show how successive covariant derivatives are necessary to properly define the generalized holonomy algebra. With regard to the later, the underlying gauge group structure of D=11 supergravity becomes manifest when its three-form field A_3 is expressed through a set of one-form gauge fields, associated with the generators of a family of enlarged supersymmetry algebras (which are fermionic extensions of the M Theory superalgebra). As it will be shown, the problem can be tackled by trivializing a standard supersymmetry algebra Chevalley-Eilenberg four-cocycle (associated to dA_3) on the enlarged superalgebras. The family of trivializing superalgebras are related to osp(1|32) through "expansion", a method to obtain new Lie (super)algebras of increasing dimensions from given ones. The analysis of the underlying gauge symmetry of eleven-dimensional supergravity leads naturally to enlarged supersymmetry algebras and superspaces. It is, thus, natural, to consider actions for objects moving in such spaces. A string moving in tensorial space is proposed, describing the excitations of a state composed of two preons (the conjectured constituents of M Theory).

Author: COBAS ALONSO MANUEL ANGEL.
Year: 2005.
University: OVIEDO.
Place of defense: FACULTAD CIENCIAS DE LA EDUCACION.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: It deals with the study of some aspects of the problem Hagedorn in String Theory at perturbativo. The phenomenon of Hagedorn is an old and well-known problem associated with the exponential growth of the density of states of the rope. This behavior was generally concrete differently depending on the theory in question, strings open, closed, open spaces or in strings ... compact, a gas generating objects, special and differential in each case. In the first part of the thesis, it takes the general study of free gas on the ropes commonly called collective microcanónico really entálpico, in the regime of Hagedorn. Already known results are obtained through a precise and detailed development, with particular emphasis on the role of the chemical and its potential implication in the average number of objects present in the gas. It clarifies and corrects some errors in the existing literature on the subject, especially those relating to the approximation of Maxwell. We apply these concepts to the study of gas ropes bosónicas, free, open dimensions. The study macrocanónico this system produces a free energy convergent when the temperature is less than or equal to that of Hagedorn, and for different temperatures higher. Addressing the problem from the microcanónico is obtained entropy which contains terms not extended. We discuss the presence of these terms and their implications physical. This first part is based on published results. In a second part of the thesis is conducting a critical review process descompactificación (opening dimensions) for the gas closed strings, as shown in another article published. From a situation where all the spatial dimensions are compactificadas circled radio autodual, examines the effect of increasing the value of the radius on the density of states for gas. This development method Euler-Maclaurin, in the version multidimensional to approximate amounts through comprehensive. It justifies a natural transition from the density of states in compact spaces and a small volume density of states which coincides with the gas closed strings in size not compact when the power is such that it does not allow for an exploration of grades freedom associated with the compactificación the size (winding modes). With this conclusion, our work contradicts a series of articles, commonly accepted, which presents a completely different picture.