Reconstruction of the join time-delay Doppler-scale reflectivity density in the wide-band regime. A frame theory based approach

The inverse scattering problem concerning the determination of the joint time-delayDoppler-scale reflectivity density characterizing continuous target environments is addressed by recourse to the generalized frame theory. A reconstruction formula,involving the echoes of a frame of outgoing signals and its corresponding reciprocalframe, is developed. A ‘‘realistic’’ situation with respect to the transmission ofa finite number of signals is further considered. In such a case, our reconstruction formula is shown to yield the orthogonal projection of the reflectivity density onto a subspace generated by the transmitted signals.

Diseño de filtros transversales mediante el híbrido de 90º

Los filtros de microondas son uno de los elementos clave en el diseño de la mayoría de sistemas de RF que soportan servicios de telecomunicaciones modernos. Algunas de las aplicaciones actuales son, por ejemplo, los nuevos sistemas radar de banda ultra ancha (UWB – Ultra Wide Band) y sistemas de transmisión de servicios multimedia, donde se requieren dimensiones pequeñas del circuito, bajas pérdidas de inserción y una alta selectividad. Una de las tendencias que ha surgido como alternativa a las teorías clásicas de diseño de filtros, es el diseño de filtros basados en técnicas de señales interferentes, conocidos como filtros transversales. En esta memoria es muestra como diseñar un filtro transversal mediante el Híbrido de 90º y mediante el Híbrido de 90º con líneas acopladas, planteando 3 posibles soluciones de la ubicación de las líneas acopladas.

Implementación de técnicas de estimación y sincronización para sistemas OFDM: aplicación directa sobre la implementación de la capa física del estándar DVB-T

El sistema de modulación ODFM es utilizado en diversas aplicaciones de banda ancha, tanto en comunicaciones por cable como en aplicaciones inalámbricas. Presenta numerosas ventajas frente a sistemas de banda ancha de portadora única ya que permite una alta eficiencia espectral, una fácil ecualización y una reducción del ISI. Por el contrario, presenta dificultades inherentes a su estructura, que son de vital importancia solventar, entre las cuales se encuentran los altos requisitos de sincronización. Este proyecto presenta métodos de sincronización de tiempo y frecuencia implementados y evaluados sobre una plataforma software basada en Matlab®, que recoge el sistema completo de transmisión basado fielmente en el estándar DVB-T. Tras una presentación de los principios de la modulación OFDM, en este documento se presenta un estudio detallado de este sistema de transmisión y su implementación, formando conjuntamente una plataforma de simulación para la evaluación de los estimadores implementados.

Rapid analysis of multiclass antibiotic residues and some of their metabolites in hospital, urban wastewater and river water by ultra-highperformance liquid chromatography coupled to quadrupole-linear ion trap tandem mass spectrometry

The present work describes the development of a fast and robust analytical method for the determination of 53 antibiotic residues, covering various chemical groups and some of their metabolites, in environmental matrices that are considered important sources of antibiotic pollution, namely hospital and urban wastewaters, as well as in river waters. The method is based on automated off-line solid phase extraction (SPE) followed by ultra-high-performance liquid chromatography coupled to quadrupole linear ion trap tandem mass spectrometry (UHPLC–QqLIT). For unequivocal identification and confirmation, and in order to fulfill EU guidelines, two selected reaction monitoring (SRM) transitions per compound are monitored (the most intense one is used for quantification and the second one for confirmation). Quantification of target antibiotics is performed by the internal standard approach, using one isotopically labeled compound for each chemical group, in order to correct matrix effects. The main advantages of the method are automation and speed-up of sample preparation, by the reduction of extraction volumes for all matrices, the fast separation of a wide spectrum of antibiotics by using ultra-high-performance liquid chromatography, its sensitivity (limits of detection in the low ng/L range) and selectivity (due to the use of tandem mass spectrometry) The inclusion of β-lactam antibiotics (penicillins and cephalosporins), which are compounds difficult to analyze in multi-residue methods due to their instability in water matrices, and some antibiotics metabolites are other important benefits of the method developed. As part of the validation procedure, the method developed was applied to the analysis of antibiotics residues in hospital, urban influent and effluent wastewaters as well as in river water samples

Ultra deep blue: the ultimate chess player

Projecte d'adaptació del programa GNU Chess al sistema de grid computing 'Condor'. I amb això, es planteja un estudi sobre els algorismes de cerca i la seva aplicació en entorns distribuïts. Una sèrie de proves sobre unes mostres de una partida d'escacs contra el propi GNU Chess ens ajuden a posar de relleu els avantatges i inconvenients de cada un dels algorismes proposats.

Rethinking economy-wide rebound measures: an unbiased proposal

In spite of having been first introduced in the last half of the ninetieth century, the debate about the possible rebound effects from energy efficiency improvements is still an open question in the economic literature. This paper contributes to the existing research on this issue proposing an unbiased measure for economy-wide rebound effects. The novelty of this economy-wide rebound measure stems from the fact that not only actual energy savings but also potential energy savings are quantified under general equilibrium conditions. Our findings indicate that the use of engineering savings instead of general equilibrium potential savings downward biases economy-wide rebound effects and upward-biases backfire effects. The discrepancies between the traditional indicator and our proposed measure are analysed in the context of the Spanish economy.

Nanotermoparells: heterounions de nanowires

Projecte de recerca elaborat a partir d’una estada a la University of California a Irvine, EEUU, entre juliol del 2007 i gener del 2008. Els termoparells són actualment els sensors de temperatura més populars i més utilitzats per a un ampli rang d’aplicacions: industrials, domèstiques, etc. Aconseguir miniaturar els dispositius fins a dimensions extremadament petites obra un ampli rang de noves aplicacions per aquests dispositius, per exemple, en el camp de la tecnologia lab-on-a-chip. En aquesta investigació, el concepte de termoparell, és a dir, dos cables de diferent metall connectats per un extrem s’ha extrapolat a l’escala nanomètrica, utilitzant nanowires com a element de construcció. Aquests nanowires s’han sintetitzat a través d’un nou procediment desenvolupat en el grup d’investigació de la Universitat de California, Irvine, que ha permès treballar amb nanowires de diferents dimensions (control independent de l’alçada i amplada) i un major grau d’èxit en la fabricació d’aquests termometres. El mètode també permet dipositar aquestes nanoestructures sobre substractes no conductors de manera controlable, simplificant notablement tot el procés de fabricació. L’obtenció d’aquests dispositius ha permès demostrar que, a part de ser bons sensors de temperatura a nivell macroscòpic (fonts de calor ambientals), també permet la determinació de temperatura a nivell microscòpic (fonts de calor focalitzada, com és el cas de feixos làser). Per a la seva caracterització ha estat necessari l’ús de tecnologia puntera (làsers, amplificadors, microscopis de forces atòmiques) i inclòs el disseny de nous dispositius. Aquests nanotermoparells presenten propietats extraordinàries, com una gran sensitivitat, gran velocitat de resposta a estímuls tèrmics, i un comportament estable vers l’ús i el temps.

Design of Novel Frequency Generation Circuit with Application to Ultra-Wideband Distributed Oscillators

Given the urgence of a new paradigm in wireless digital trasmission which should allow for higher bit rate, lower latency and tigher delay constaints, it has been proposed to investigate the fundamental building blocks that at the circuital/device level, will boost the change towards a more efficient network architecture, with high capacity, higher bandwidth and a more satisfactory end user experience. At the core of each transciever, there are inherently analog devices capable of providing the carrier signal, the oscillators. It is strongly believed that many limitations in today's communication protocols, could be relieved by permitting high carrier frequency radio transmission, and having some degree of reconfigurability. This led us to studying distributed oscillator architectures which work in the microwave range and possess wideband tuning capability. As microvave oscillators are essentially nonlinear devices, a full nonlinear analyis, synthesis, and optimization had to be considered for their implementation. Consequently, all the most used nonlinear numerical techniques in commercial EDA software had been reviewed. An application of all the aforementioned techniques has been shown, considering a systems of three coupled oscillator ("triple push" oscillator) in which the stability of the various oscillating modes has been studied. Provided that a certain phase distribution is maintained among the oscillating elements, this topology permits a rise in the output power of the third harmonic; nevertheless due to circuit simmetry, "unwanted" oscillating modes coexist with the intenteded one. Starting with the necessary background on distributed amplification and distributed oscillator theory, the design of a four stage reverse mode distributed voltage controlled oscillator (DVCO) using lumped elments has been presented. All the design steps have been reported and for the first time a method for an optimized design with reduced variations in the output power has been presented. Ongoing work is devoted to model a wideband DVCO and to implement a frequency divider.

Research development of terahertz imaging systems

The electromagnetic radiation at a terahertz frequencies (from 0.1 THz to 10 THz) is situated in the frequency band comprised between the optical band and the radio band. The interest of the scientific community in this frequency band has grown up due to its large capabilities to develop innovative imaging systems. The terahertz waves are able to generate extremely short pulses that achieve good spatial resolution, good penetration capabilities and allow to identify microscopic structures using spectral analysis. The work carried out during the period of the grant has been based on the developement of system working at the aforementioned frequency band. The main system is based on a total power radiometer working at 0.1 THz to perform security imaging. Moreover, the development of this system has been useful to gain knowledge in the behavior of the component systems at this frequency band. Moreover, a vectorial network analyzer has been used to characterize materials and perform active raster imaging. A materials measurement system has been designed and used to measure material properties as permittivity, losses and water concentration. Finally, the design of a terahertz time-domain spectrometer (THz-TDS) system has been started. This system will allow to perform tomographic measurement with very high penetration resolutions while allowing the spectral characterization of the sample material. The application range of this kind of system is very wide: from the identification of cancerous tissues of a skin to the characterization of the thickness of a painted surface of a car.

Growth and characterization of CoO ultra thin films

In this report we present the growth process of the cobalt oxide system using reactive electron beam deposition. In that technique, a target of metallic cobalt is evaporated and its atoms are in-flight oxidized in an oxygen rich reactive atmosphere before reaching the surface of the substrate. With a trial and error procedure the deposition parameters have been optimized to obtain the correct stoichiometry and crystalline phase. The evaporation conditions to achieve the correct cobalt oxide salt rock structure, when evaporating over amorphous silicon nitride, are: 525 K of substrate temperature, 2.5·10-4 mbar of oxygen partial pressure and 1 Å/s of evaporation rate. Once the parameters were optimized a set of ultra thin film ranging from samples of 1 nm of nominal thickness to 20nm thick and bulk samples were grown. With the aim to characterize the samples and study their microstructure and morphology, X-ray diffraction, transmission electron microscopy, electron diffraction, energy dispersive X-ray spectroscopy and quasi-adiabatic nanocalorimetry techniques are utilised. The final results show a size dependent effect of the antiferromagnetic transition. Its Néel temperature becomes depressed as the size of the grains forming the layer decreases.

Calculation of Franck-Condon factors including anharmonicity: simulation of the C2 H4+ X̃2B 3u←C2 H4X̃1 Ag band in the photoelectron spectrum of ethylene

Our new simple method for calculating accurate Franck-Condon factors including nondiagonal (i.e., mode-mode) anharmonic coupling is used to simulate the C2H4+X2B 3u←C2H4X̃1 Ag band in the photoelectron spectrum. An improved vibrational basis set truncation algorithm, which permits very efficient computations, is employed. Because the torsional mode is highly anharmonic it is separated from the other modes and treated exactly. All other modes are treated through the second-order perturbation theory. The perturbation-theory corrections are significant and lead to a good agreement with experiment, although the separability assumption for torsion causes the C2 D4 results to be not as good as those for C2 H4. A variational formulation to overcome this circumstance, and deal with large anharmonicities in general, is suggested

Determination of the direct band-gap energy of InAlAs matched to InP by photoluminescence excitation spectroscopy

A series of InxAl1-xAs samples (0.51≪x≪0.55)coherently grown on InP was studied in order to measure the band-gap energy of the lattice matched composition. As the substrate is opaque to the relevant photon energies, a method is developed to calculate the optical absorption coefficient from the photoluminescence excitation spectra. The effect of strain on the band-gap energy has been taken into account. For x=0.532, at 14 K we have obtained Eg0=1549±6 meV

Genome-wide screen of genes required for caffeine tolerance in fission yeast

Background: An excess of caffeine is cytotoxic to all eukaryotic cell types. We aim to study how cells become tolerant to atoxic dose of this drug, and the relationship between caffeine and oxidative stress pathways.Methodology/Principal Findings: We searched for Schizosaccharomyces pombe mutants with inhibited growth on caffeinecontainingplates. We screened a collection of 2,700 haploid mutant cells, of which 98 were sensitive to caffeine. The genes mutated in these sensitive clones were involved in a number of cellular roles including the H2O2-induced Pap1 and Sty1 stress pathways, the integrity and calcineurin pathways, cell morphology and chromatin remodeling. We have investigated the role of the oxidative stress pathways in sensing and promoting survival to caffeine. The Pap1 and the Sty1 pathways are both required for normal tolerance to caffeine, but only the Sty1 pathway is activated by the drug. Cells lacking Pap1 aresensitive to caffeine due to the decreased expression of the efflux pump Hba2. Indeed, ?hba2 cells are sensitive to caffeine, and constitutive activation of the Pap1 pathway enhances resistance to caffeine in an Hba2-dependent manner. Conclusions/Significance: With our caffeine-sensitive, genome-wide screen of an S. pombe deletion collection, we havedemonstrated the importance of some oxidative stress pathway components on wild-type tolerance to the drug.

The Big Band Theory : català col·loquial i humor científic. Proposta de traducció del capítol pilot

Aquest treball elabora una proposta de traducció per al doblatge del capítol pilot de The Big Bang Theory, que combina llenguatge col•loquial i llenguatge científic.L’objectiu és doble: elaborar un llenguatge col•loquial creïble però a la vegada genuí i emprar els equivalents catalans adequats per als termes científics originals.