Дисертації з теми "PLANCK Data"

Le sujet principal de mon travail de thèse est le logiciel de modélisation des radiomètres de l'instrument basse fréquence (LFI). LFI est l'un des deux instruments embarqués sur le satellite Planck de l'Agence spatiale européenne pour le mesurage de haute précision des anisotropies du rayonnement fossile. Le modèle logiciel s'appuie sur la réponse en fréquence mesurée des radiomètres éléments sur un simulateur de guide d'ondes analytique dans le but de simuler la réponse en fréquence du LFI canal par canal. Sa mise en œuvre est basée sur QUCS, un simulateur de circuit libre. La bande passante modélisée a montré la bonne cohérence avec les performances mesurées et moins a souffert des effets systématiques, ils sont donc les meilleures estimations disponibles pour la réponse en fréquence des radiomètres. Grâce à la collaboration avec Jean-Michel Lamarre, Instrument Scientist du HFI, l'instrument bolometrique de Planck, l'accent de mor activité a été élargie et a inclus l'étude de la corrélation croisée entre HFI et LFI données, sur deux aspects principaux: le calcul des fonctions de transfert thermique de l'étape à 4K au cours des tests et des simulations. Le 4K étape est un élément clé da la chaîne cryogénique de HFI, et c'est utilisée comme une charge de référence stable par LFI. Le projet des sessions de quick look analysis (QLA) que exploitent données scientifiques et housekeeping de ces deux instruments dans le but d'identifier les effets systématiques. Les sessions reposent sur le logiciel de visualisation de données KST et sont composées d'un ensemble de sessions de base déjà mis en œuvre et testées, permettant par exemple de produire spectra et corrélations croisée et une série de sessions avancées, dédiées à l'étude d'un aspect spécifique, par exemple la corrélation entre canaux de 70 GHz de Ll de 100 GHz de HFI
The main topic of my PhD work is the software modelling of the Low Frequency Instrument (LFI) radiometers. The LFI is one of the two instruments on-board the European Space Agency Planck Mission for high precision measurements of the anisotropies of the Cosmic Microwave Background (CMB). The software model relies on measured frequency response of the LFI radiometers components and on an analytical waveguide simu in order to simulate the LFI bandpasses channel by channel. Its implementation is based on QUCS, an open-source circuit Simulator. Modelled bandpasses showed good consistency with the measured performance and suffered less systematic effects, they are therefore the best estimate available for the radiometers frequency response. Thanks to the collaboration with Jean-Michel Lamarre, HFI Instrument Scientist, the bolometric instrument on-board Planck, the focus my activity was broadened and included the study of cross-correlation between HFI and LFI data, on two main aspects: The computation of the thermal transfer functions of the stage at 4K during tests and from simulations. The 4K stage is a key element the HFI cryogenic chain and it is used as a stable reference load by LFI. The design of quick look analysis sessions exploiting both instruments scientific and housekeeping data in order to identify systematic effects. Sessions relies on the data visualization software KST and consist of a set of already implemented and tested basic sessions allowing for example to produce spectra and cross-correlations, and a set of advanced sessions, dedicated on the study of a specific aspect, for example the correlation between LFI 70 GHz and HFI 100 GHz channels

The main topic of my PhD work is the software modelling of the ESA Planck Low Frequency Instrument (LFI) radiometers. The software model, implemented in QUCS, relies on measured frequency response of the LFI radiometers components and on an analytical waveguide simulator in order to simulate the LFI bandpasses channel by channel. Modelled bandpasses showed good consistency with the measured performance and suffered less systematic effects, they are therefore the best estimate available for the radiometers frequency response. Thanks to the collaboration with Jean-Michel Lamarre, HFI Instrument Scientist, the bolometric instrument on-board Planck, the focus of my activity was broadened and included the study of cross-correlation between HFI and LFI data, on two main aspects: The computation of the thermal transfer functions of the stage at 4K during tests and from simulations. The 4K stage is a key element in the HFI cryogenic chain and it is used as a stable reference load by LFI. The design of quick look analysis sessions exploiting both instruments scientific and housekeeping data in order to identify systematic effects. Sessions relies on the data visualization software KST and consist of a set of already implemented and tested basic sessions, allowing for example to produce spectra and cross-correlations, and a set of advanced sessions, dedicated on the study of a specific aspect, for example the correlation between LFI 70 GHz and HFI 100 GHz channels.

We present maps of the Large and Small Magellanic Clouds from combined South Pole Telescope (SPT) and Planck data. The Planck satellite observes in nine bands, while the SPT data used in this work were taken with the three-band SPT-SZ camera, The SPT-SZ bands correspond closely to three of the nine Planck bands, namely those centered at 1.4, 2.1, and 3.0 mm. The angular resolution of the Planck data ranges from 5 to 10 arcmin, while the SPT resolution ranges from 1.0 to 1.7 arcmin. The combined maps take advantage of the high resolution of the SPT data and the long-timescale stability of the space-based Planck observations to deliver robust brightness measurements on scales from the size of the maps down to similar to 1 arcmin. In each band, we first calibrate and color-correct the SPT data to match the Planck data, then we use noise estimates from each instrument and knowledge of each instrument's beam to make the inverse-variance-weighted combination of the two instruments' data as a function of angular scale. We create maps assuming a range of underlying emission spectra and at a range of final resolutions. We perform several consistency tests on the combined maps and estimate the expected noise in measurements of features in them. We compare maps from this work to those from the Herschel HERITAGE survey, finding general consistency between the data sets. All data products described in this paper are available for download from the NASA Legacy Archive for Microwave Background Data Analysis server.

Cette thèse est dédiée à l'étude de la polarisation de la poussière interstellaire et est principalement basée sur l'analyse des données du satellite Planck. Tout d'abord, nous caractérisons le biais sur les paramètres de polarisation déduits des données. Nous avons mis en évidence que ce biais dépend non seulement du niveau de bruit, mais également de la corrélation entre les bruits sur les paramètres de Stokes. Nous avons développé des méthodes optimisées d'estimation de la fraction de polarisation, de l'angle de polarisation et de la fonction de dispersion de l'angle de polarisation, qui tiennent compte de la forme des matrices de covariance du bruit. Nous avons montré pour la première fois que le comportement du biais sur la fonction de dispersion d'angle est non trivial, et nous avons proposé une méthode pour évaluer la limite supérieure du biais que nous avons appliqué aux données Planck de la bande à 353 GHz. Nous avons étudié la corrélation entre la fraction de polarisation et la fonction de dispersion d'angle, ainsi que la corrélation entre la fraction de polarisation et la densité de colonne de gaz, sur de grandes fractions du ciel. Ceci nous a permis de mettre en évidence que la structure à 3 dimensions du champ magnétique affecte fortement la fraction de polarisation observée. Lorsque la direction du champ magnétique change le long de la ligne de visée ou dans le faisceau du télescope, on observe que la fraction de polarisation diminue. Nous avons comparé ce résultat à des simulations numériques basées sur la MHD magnétohydrodynamique). Une dépendance similaire de la fraction de polarisation avec la géométrie du champ magnétique y est observée. La diminution de la fraction de polarisation avec la densité de colonne était observée dans les nuages moléculaires dans des études précédentes. Nous avons généralisé ce résultat comme étant également caractéristique du milieu diffus à grande échelle. En combinaison avec les résultats des simulations MHD où un comportement similaire est observé, ceci indique que la diminution de la fraction de polarisation est principalement due aux changements de direction du champ magnétique le long de la ligne de visée. Nous avons pour la première fois déterminé la limite inférieure de la fraction de polarisation maximale réelle bservée avec Planck. Cette limite pourrait correspondre au niveau de polarisation intrinsèque de la poussière interstellaire dans les conditions les plus favorables de la géométrie du champ magnétique. De plus, la comparaison entre la polarisation en émission et en extinction nous a permis d'établir le rapport entre la fraction de polarisation dans les domaines sub-millimétrique et visible. Ce résultat apporte une contrainte forte pour de futurs modèles de la poussière interstellaire. Enfin, nous avons effectué une étude préliminaire sur les propriétés en polarisation des associations de coeurs froid détectés avec Planck. Cette analyse statistique nous permet de confirmer la diminution de la fraction de polarisation dans ces milieux, par rapport à l'environnement local à grande échelle. Nous discutons son origine en termes de perte d'efficacité de l'alignement des grains dans ces associations de coeurs denses
This thesis is dedicated to the study of Galactic dust polarization and is mostly based on the analysis of the Planck satellite data. First, we characterize the bias on polarization parameters which are derived from the measurements. We have evidenced that it depends not only on the noise level but also on the noise correlation between the Stokes parameters. We have developed optimized methods to estimate the polarization fraction, angle and angle dispersion function, that take into account the shape of the noise covariance matrices. The peculiarity of the bias on the polarization angle dispersion function is shown for the first time, and a method for the evaluation of the upper limit on the bias is proposed and applied to the Planck 353 GHz data. We study the correlation between the polarization fraction and the polarization angle dispersion function, and also the correlation between the polarization fraction and the gas column density, over large fractions of the sky. As a result, we show that the three-dimensional structure of the magnetic field highly affects the observed polarization fraction. When the magnetic field direction changes along the line of sight or within the telescope beam, the observed polarization decreases. We observe a similar dependance of the polarization fraction with the magnetic field geometry in MHD (magnetohydrodynamics) simulations. We have evidenced the systematic decrease of the polarization fraction with column density, previously observed only in dense molecular clouds, to be general also at large scales and in the diffuse ISM. In combination with the results from MHD simulations, where a similar behavior is observed, this observational fact indicates that the decrease in the polarization fraction is mostly due to the magnetic field tangling along the line of sight. We derive for the first time the lower limit of the maximum polarization fraction observed with Planck, which could correspond to the dust intrinsic polarization fraction when the field geometry is most favorable. In addition, comparing polarization in emission with Planck and in extinction from stars observations, we find a high sub-millimeter to visible polarization fraction ratio, which will be a strong constraint for future dust models. Finally, we have performed a preliminary study on the polarization properties of Galactic cold clumps detected with Planck. This statistical analysis allows us to confirm the existence of a significant drop of the polarization fraction in the clumps, relatively to the local large scale environment. We discuss its origin in terms of efficiency loss of grain alignment in these dense clumps

We present a cosmic microwave background (CMB) lensing map produced from a linear combination of South Pole Telescope (SPT) and Planck temperature data. The 150 GHz temperature data from the 2500 deg(2) SPT-SZ survey is combined with the Planck 143 GHz data in harmonic space to obtain a temperature map that has a broader l coverage and less noise than either individual map. Using a quadratic estimator technique on this combined temperature map, we produce a map of the gravitational lensing potential projected along the line of sight. We measure the auto-spectrum of the lensing potential C-L(phi phi), and compare it to the theoretical prediction for a.CDM cosmology consistent with the Planck 2015 data set, finding a best-fit amplitude of 0.95(-0.06)(+0.06) (stat.)(-0.01)(+0.01)+ (sys.). The null hypothesis of no lensing is rejected at a significance of 24 sigma. One important use of such a lensing potential map is in cross-correlations with other dark matter tracers. We demonstrate this cross-correlation in practice by calculating the cross-spectrum, C-L(phi) G, between the SPT+ Planck lensing map and Wide-field Infrared Survey Explorer (WISE) galaxies. We fit C-L(phi G) to a power law of the form p(L) = a(L/L-0)(-b) with a, L-0, and b fixed, and find eta(phi G) = C-L(phi G)/p(L) = 0.94(-0.04)(+0.04), which is marginally lower, but in good agreement with eta(phi G) = 1.00-(+0.02)(0.01), the best-fit amplitude for the cross-correlation of Planck-2015 CMB lensing and WISE galaxies over similar to 67% of the sky. The lensing potential map presented here will be used for cross-correlation studies with the Dark Energy Survey, whose footprint nearly completely covers the SPT 2500 deg(2) field.

We study the consistency of 150 GHz data from the South Pole Telescope (SPT) and 143 GHz data from the Planck satellite over the patch of sky covered by the SPT-SZ survey. We first visually compare the maps and find that the residuals appear consistent with noise after accounting for differences in angular resolution and filtering. We then calculate (1) the cross-spectrum between two independent halves of SPT data, (2) the cross-spectrum between two independent halves of Planck data, and (3) the cross-spectrum between SPT and Planck data. We find that the three cross-spectra are well fit (PTE = 0.30) by the null hypothesis in which both experiments have measured the same sky map up to a single free calibration parameter-i.e., we find no evidence for systematic errors in either data set. As a by-product, we improve the precision of the SPT calibration by nearly an order of magnitude, from 2.6% to 0.3% in power. Finally, we compare all three cross-spectra to the full-sky Planck power spectrum and find marginal evidence for differences between the power spectra from the SPT-SZ footprint and the full sky. We model these differences as a power law in spherical harmonic multipole number. The best-fit value of this tilt is consistent among the three cross-spectra in the SPT-SZ footprint, implying that the source of this tilt is a sample variance fluctuation in the SPT-SZ region relative to the full sky. The consistency of cosmological parameters derived from these data sets is discussed in a companion paper.

We measure the cross-correlation between weak lensing of galaxy images and of the cosmic microwave background (CMB). The effects of gravitational lensing on different sources will be correlated if the lensing is caused by the same mass fluctuations. We use galaxy shape measurements from 139 deg(2) of the Dark Energy Survey (DES) Science Verification data and overlapping CMB lensing from the South Pole Telescope (SPT) and Planck. The DES source galaxies have a median redshift of z(med) similar to 0.7, while the CMB lensing kernel is broad and peaks at z similar to 2. The resulting cross-correlation is maximally sensitive to mass fluctuations at z similar to 0.44. Assuming the Planck 2015 best-fitting cosmology, the amplitude of the DESxSPT cross-power is found to be A(SPT) = 0.88 +/- 0.30 and that from DESxPlanck to be A(Planck) = 0.86 +/- 0.39, where A = 1 corresponds to the theoretical prediction. These are consistent with the expected signal and correspond to significances of 2.9 sigma and 2.2 sigma, respectively. We demonstrate that our results are robust to a number of important systematic effects including the shear measurement method, estimator choice, photo-z uncertainty and CMB lensing systematics. We calculate a value of A = 1.08 +/- 0.36 for DESxSPT when we correct the observations with a simple intrinsic alignment model. With three measurements of this cross-correlation now existing in the literature, there is not yet reliable evidence for any deviation from the expected LCDM level of cross-correlation. We provide forecasts for the expected signal-to-noise ratio of the combination of the five-year DES survey and SPT-3G.

Le fond diffus cosmologique (CMB), relique du Big-Bang chaud, porte les traces à la fois de la formation des structures des époques récentes et des premières phases énergétiques de l'Univers.Le satellite Planck, en service de 2009 à 2013, a fourni des mesures de haute qualité des anisotropies du CMB. Celles-ci sont utilisés dans cette thèse pour déterminer les paramètres du modèle cosmologique standard et autour du secteur des neutrinos.Ce travail décrit la construction d'un fonction de vraisemblance pour les hauts-l de Planck. Cela implique une stratégie de masquage pour l'émission thermique de la Galaxie ainsi que pour les sources ponctuelles. Les avant-plans résiduels sont traités directement au niveau du spectre de puissance en utilisant des templates physiques bases sur des études de Planck.Les méthodes statistiques nécessaires pour extraire les paramètres cosmologiques dans la comparaison entre les modèles et les données sont décrites, à la fois la méthode bayésienne de Monte-Carlo par chaînes de Markov et la technique fréquentiste du profil de la fonction de vraisemblance.Les résultats sur les paramètres cosmologiques sont présentés en utilisant les données de Planck seul et en combinaison avec les données à petites échelles des expériences de CMB basées au sol (ACT et SPT), avec les contraintes provenant des mesures des oscillations acoustiques des baryons (BAO) et des supernovae. Les contraintes sur l'échelle absolue de la masse des neutrinos et sur le nombre effectif de neutrinos sont également discutées
The cosmic microwave background (CMB), relic of the hot Big-Bang, carries the traces of both the rich structure formation of the late time epochs and the energetic early phases of the universe.The Planck satellite provided, from 2009 to 2013, high-quality measurements of the anisotropies of the CMB. These are used in this thesis to determine the parameters of the standard cosmological model and of the extension concerning the neutrino sector. The construction of an high-l Planck likelihood is detailed. This involves a masking strategy that deals in particular with the contamination from thermal emission of the Galaxy. The residual foregrounds are treated directly at the power spectrum level relying on physically motivated templates based on Planck studies.The statistical methods needed to extract the cosmological parameters in the comparison between models and data are described, both the Bayesian Monte Carlo Markov Chain techniques and the frequentist profile likelihood. Results on cosmological parameters are presented using Planck data alone and in combination with the small scale data from the ground based CMB experiment ACT and SPT, the Baryon Acoustic Oscillation and the Supernovae. Constraints on the absolute scale of neutrino masses and of the number of effective neutrino are also discussed

Le satellite Planck est le satellite de troisième génération visant à observer le fond diffus cosmologique. La résolution et la sensibilité de ses instruments permettent pour la première fois de mettre en évidence les effets de lentille gravitationnelle subis par les photons du fond diffus cosmologique. Cette thèse présente une méthode originale de détection de ces effets dans les données de l'instrument HFI de Planck.La première partie donne dans un premier temps, une description générale du modèle standard de la cosmologie et de la physique du fond diffus cosmologique. Elle aborde ensuite en détails l'effet de lentille gravitationnelle, en se concentrant plus particulièrement sur son impact sur les observables du fond diffus cosmologique. Elle termine par une présentation du satellite Planck et de ses instruments.La seconde partie se concentre sur la description d'un ensemble d'outils de simulations et d'analyse que j'ai développé au cours de ma thèse afin de réaliser la première détection des effets de lentille gravitationnelle sur le fond diffus cosmologique. Elle présente la méthode originale employée qui repose sur une analyse des cartes du ciel par morceaux, permettant de s'affranchir des zones du ciel les plus contaminées. On trouvera également dans cette partie une caractérisation, de l'estimateur du champ de potentiel de lentille, pour des cartes masquée, en présence de bruit inhomogène ainsi que la présentation d'une méthode pour corriger les biais de l'analyse à l'aide de simulations Monte-Carlo.La dernière partie, est consacrée au travail sur les données de l'instrument HFI. Le premier chapitre présente l'application de la méthode d'analyse précédente aux cartes des observations combinées à 143GHz et 217GHz ainsi que la carte issue de la séparation des composantes avec l'algorithme GMCA. Les résultats montrent un spectre de puissance de la déflexion compatible avec le spectre attendu, dans un modèle lambda CMB, calculé à partir des paramètres cosmologiques issus de WMAP intégrant sept années d'observations. Les points de mesure, issus du spectre combiné des cartes à 143GHz et 217GHz, pour les multipôles inférieurs à 500, donnent un Chi2 par degré de liberté de 1.26. Finalement, le dernier chapitre présente l'algorithme de compression des données de l'instrument HFI à bord du satellite. Il traite en détail le réglage et le suivi des paramètres de compression et du débit des données, depuis le lancement du satellite et fait le bilan sur les erreurs de compression rencontrées

As well as providing us with a snapshot of the Universe at the time of recombination, the cosmic microwave backround (CMB) radiation carries a wealth of information about the later evolution of the Universe through the so-called CMB secondary anisotropies that originates from the interaction between CMB photons and the Large Scale Structure (LSS). This thesis deals with two of these effects: the CMB lensing and the kinematic Sunyaev-Zel'dovich (kSZ). In particular, we present the first cross-correlation analysis between the CMB lensing maps reconstructed by Planck team and the angular position of galaxies from the Herschel H-ATLAS survey, the highest redshift sample exploited for cross-correlation analysis to date. By splitting the galaxy catalog in two redshift bins, we also attempt a tomographic analysis of the signal and reconstruct the galaxy bias evolution over cosmic time. On the other hand, the kSZ effect measures the integrated free electron momentum up to high redshift, thus being sensitive to the cosmic flows and the reionization history. Here we study its capabilities in constraining theories of modified gravity.

Le satellite Planck a été conçu pour mesurer de manière ultime les anisotropies primairesen température du fond diffus cosmologique (CMB), et améliorer les contraintes existantes sursa polarisation. La première partie de cette thèse s'inscrit dans le cadre du traitement des donnéesde l'instrument à haute fréquence de ce satellite. Les propriété statistiques du bruit sonttestée. Des effets systématiques dans l'estimateur du bruit sont ainsi détectés, et certains ontpu être corrigés. La sélection des données à projeter sur les cartes est ensuite présentée, ainsique la validation de la qualité de ces données. Cette sélection est finalement comparée à unesélection pour laquelle les critères sont beaucoup plus sévères, afin de vérifier que l'impactdes données imparfaites résiduelles est négligeable. Nous montrons que les données validéespour une utilisation scientifique répondent bien aux exigences de gaussianité et de stationnarité: des effets instrumentaux ne devraient pas induire de fausses conclusions cosmologiques.La seconde partie porte sur l'interprétation des données ainsi obtenues. Le modèle de concordanceest présenté, ainsi que les résultats rendus publiques par la collaboration Planck en 2013.La troisième partie est dédiée à deux études phénoménologiques concernant l'ionisation del'Univers. Premièrement, l'influence de l'annihilation de matière noire sur le spectre du CMBest étudiée : une méthode pour estimer l'impact de l'incertitude des canaux par lesquels sefont ces dépôts d'énergie est développée. Il ressort que les hypothèses sur la façon exacte dontl'énergie s'injecte dans le plasma ne sont pas cruciales pour retrouver les paramètres associée àl'annihilation. Deuxièmement, l'époque de la Réionisation et son rôle dans le spectre du CMBest présentée, avec l'analyse d'une paramétrisation de la fraction d'ionisation. Nous montronsla fiabilité des différents algorithmes dans le cas où la fraction d'ionisation est constante parmorceaux, c'est-à-dire même en présence de fortes discontinuités.

Includes bibliographical references (leaves 63-65).
This study derived the mobility and diffusion coefficients of a Fokker-Planck equation describing a vacancy hopping in inhomogeneous media in one dimension under a directed stress. The study used the general master equation as a basis for a physical model because of the mesoscopic view that the change in average concentration is inadequate to describe small fluctuations in a system and that a probabilistic approach is needed. By van Kampen's system-size expansion a master equation was expanded to obtain a nonlinear Fokker-Planck equation of the diffusive type. The Einstein relation was obtained and satisfied. As an application to a physical system we considered the simple one dimension case of a point defect diffusing by a hopping mechanism under an applied stress using data obtained from the implantation of krypton ions on a pre-existing stress state in polycrystalline titanium. From this data we estimated the stress gradient and from literature used the vacancy migration enthalpy to find the diffusion coefficients, and by the Einstein relation, the mobility, the coefficients of a Fokker-Planck equation. As an application to a non physical system the study set up a Fokker-Planck equation which described incremental changes in foreign exchange (FX) prices. The Fokker-Planck equation was completely determined by the drift and diffusion coefficients extracted directly from the actual FX prices. The purpose here was to show the importance of a 'physical model' or the existence of the Markov property for the establishment of a Fokker-Planck equation and by starting from a master equation for non physical systems which would make for better understanding of the underlying statistical equations of motion of the fluctuating system.

La prévision de l'évolution des déchets radioactifs lors d'un stockage en couche géologique argileuse profonde nécessite une bonne compréhension du transport de l'eau et des ions dans l'argile. Leur diffusion dans ce milieu poreux et chargé est décrite par des paramètres empiriques, comme le coefficient de distribution (Kd) qui rend compte des interactions avec les surfaces minérales. Notre travail a porté sur la pertinence de ce concept et sa définition à partir de processus microscopiques.

Nous avons d'abord modélisé la contribution ionique aux propriétés diélectriques des argiles, et proposé une détermination de Kd par spectroscopie diélectrique.

Nous avons ensuite calculé par simulations microscopiques (Monte-Carlo et dynamique moléculaire) les enthalpies libres et enthalpies d'échange ionique pour les ions alcalins, qui contrôlent Kd et ses variations avec la température T. Les résultats pour le césium sont en bon accord avec des mesures de microcalorimétrie et de Kd en fonction de T.

Après avoir contribué au développement d'une nouvelle méthode de simulation sur réseau (Lattice Fokker-Planck), nous l'avons utilisée pour établir un lien explicite entre la dynamique microscopique des ions et le modèle de diffusion-réaction qui sous-tend la notion de Kd.

Enfin, nous avons étudié par simulation de dynamique moléculaire la cinétique d'échange d'eau et d'ions entre les particules d'argile (porosité interfoliaire) et la porosité extra-particulaire. Les résultats confirment les hypothèses généralement admises selon lesquelles l'eau et les cations peuvent explorer toute la porosité, tandis que les anions sont exclus des espaces interfoliaires.

Le premier sujet d'étude est l'application des méthodes de dynamique de gaz sur réseau en champ moyen à l'électrochimie, en particulier à l'électrocristallisation. Le présent modèle, issu de la physique statistique, utilise des équations cinétiques mi-croscopiques en champ moyen, pour décrire l'évolution des cinq espèces en présence: métal, cation, anion, solvant et espèce électronique. En établissant ces équations à partir de considérations microscopiques, nous cherchons à modéliser la croissance de structures arborescentes sur la cathode, en tenant compte des effets d'anisotropie cristalline et de la mobilité des espèces, du potentiel appliqué et du taux de transfert électronique. Pour valider le modèle numériquement, nous commençons par étudier des systèmes unidi-mensionnels simplifiés, puis montrons qu'il est possible d'obtenir des croissances arbores-centes bidimensionnelles. Le deuxième sujet est une approche analytique de la DLA dans un modèle plus limité de croissance d'aiguilles, par la méthode classique de transformation conforme. Le point nouveau est de modifier le modèle, en supposant que la croissance est discrète et proba-biliste. Ceci permet d'obtenir une équation discrète de Fokker-Planck sur la probabilité de trouver au temps t une distribution donnée des longueurs d'aiguilles. En supposant un scénario de croissance hiérarchique, avec doublements de période suc-cessifs, on retrouve analytiquement la distribution d'aiguilles en fonction de la hauteur, prévue numériquement par des études antérieures.

L'obiettivo di questo lavoro di tesi è quello di presentare le caratteristiche della radiazione di fondo che ci si aspetta di osservare in base alla descrizione teorica del suo processo di emissione e confrontarle con quanto emerge da un'analisi di alcuni dei prodotti definitivi della missione Planck, pubblicati nel 2018. A tale scopo è stata utilizzata la libreria Healpy, scritta in Python e basata sull'algoritmo per la discretizzazione di funzioni definite su una sfera HEALPix.

Cette thèse a le but d'introduire le concept de l'inertie dans la dynamique dissipative du macrospin. En suivant le travail de T. L. Gilbert dans cette direction, une masse est associée au macrospin, qui n'est pas liée au mouvement d'une masse réelle, mais à l'inertie du macrospin. Comme conséquence, une forme généralisée de l'équation dynamique du Gilbert tenant compte de l'inertie du macrospin est obtenue. A l'échelle d'une nanostructure ferromagnétique, les fluctuations sont relevantes. Le macrospin suit un mouvement Brownien dans l'espace de configuration correspondant (une sphère de rayon Ms). Pour faire une description de la dynamique du macrospin, une simple, rigoureuse et nouvelle théorie, celle de la thermodynamique mésoscopique hors équilibre est utilisée comme alternative au formalisme des processus stochastiques utilisé par W. F. Brown Jr. L'état de l'aimantation est décrit par un nombre de degrés de liberté qui influencent la dynamique du système : l'orientation m de l'aimantation décrite par les angles (θ, φ) et la vitesse u = dm/dt , ou le moment cinétique L. Une fonction de distribution f est introduite liée à la probabilité de trouver l'aimantation dans un état particulier (m, u) ou (m,L). La combination de la définition statistique de l'entropie comme une fonction de la probabilité, avec la méthodologie systèmatique de la thermodynamique hors equilibre résulte dans une théorie puissante décrivant pas seulement la dynamique moyennée du macrospin, mais aussi les fluctuations autour de la moyenne. Donc, une équation généralisée dynamique de Gilbert et une équation généralisée stochastique de Brown sont obtenues avec la théorie MNET. Un temps de relaxation est défini dépendent de l'inertie et du coefficient de dissipation du macrospin. Le comportement de l'aimantation impose deux régimes : un régime inertiel ou des temps courts t << τ , et le régime de diffusion ou des temps longs t >> τ . Un nouveau phénomène, la nutation, est prédite dans le régime inertiel, tandis que l'équation dynamique de Gilbert et l'équation stochastique de Brown sont obtenues aux temps longs. De plus, la question sur l'application de MNET dans le domaine de la spintronique est posée dans le contexte du spin transfer. Un modèle à deux fluides en rotation est présenté pour les spins s des électrons de conduction et les spins d des électrons constituant l'aimantation. Le modèle est intéressant proche de la interface normal-ferromagnet où se trouve accumulation de spin.

Planar nanostructures made of noble metal can efficiently control transmission of light, thanks to surface plasmon polaritons (SPPs) mediated through interaction between such a structure and incoming light. In this thesis, we numerically characterize, with a 3D finiteelement method, three types of plasmonic devices: plasmonic radial/azimuthal filter, plasmonic quarter-wave plate made of a periodic array of round holes in a thin metallic film, and a plasmonic quarter-wave plate with a periodic array of cross-shaped apertures. The plasmonic polarization filter is formed by a series of concentric equidistant gold rings, and it can transmit the radially polarized light and block the azimuthally polarized light. The quarter-wave plate with round holes has a different lattice constant along two Cartesiancoordinate directions that enable different phase retardations for two orthogonally polarized incident waves; hence, it can convert a linearly polarized light to a circularly polarized light. For the quarter-wave plate with an array of cross-shaped apertures, it utilizes the different lengths of horizontal/vertical arms to manipulate the phase retardations. All of these devices have sub-micron thicknesses, unlike their traditional counterparts that are bulky and inconvenient for integration purposes. Fabrication of the wave plate with cross-shaped apertures was attempted in collaboration with members in the Optics and Photonics unit at KTH.

La detecció de la primera estrella binària més de 200 anys enrere va representar l'inici de tot un nou camp de l'astrofísica dedicat a l'estudi de l'evolució i les interaccions d'aquests sistemes, fent servir com a principal eina l'anàlisi del moviment reflex causat pel company orbitant. Va ser només qüestió de temps que els instruments de mesura assolissin un nivell de precisió prou elevat per a detectar els moviments induïts per planetes sobre les seves estrelles. El descobriment del primer exoplaneta fa quasi tres dècades va suposar la creació d'un reguitzell de projectes dedicats a la cerca de nous mons, els quals estan produint un munt de dades que també estan essent utilitzades amb la finalitat d'estudiar diferents propietats de les estrelles. L'objectiu principal d'aquesta tesi és l'estudi i caracterització d'exoplanetes, estrelles i sistemes estel·lars mitjançant l'anàlisi de dades provinents de projectes dedicats a la cerca d'exoplanetes amb instruments d'alta precisió. Aquest és el cas dels projectes CARMENES i TESS, que tenen l'objectiu de trobar planetes fent servir el mètode de la velocitat radial i la detecció de trànsits planetaris, respectivament, posant un èmfasi especial en estrelles de tipus M. Primerament, hem desenvolupat un nou mètode per a determinar les propietats de les taques estel·lars i dels moviments convectius en estrelles M usant la variabilitat induïda per l'activitat estel·lar. En particular, hem modelat les velocitats radials cromàtiques i la fotometria de l'estrella YZ CMi fent servir el software de modelatge d'activitat estel·lar StarSim. L'anàlisi ha revelat la presència d'una gran taca polar amb una temperatura 200 K inferior a la de l'estrella, trobant també que el moviment convectiu de l'estrella podria tenir un moviment invers a l'esperat. A partir d'un anàlisi combinat de velocitats radials antigues i de CARMENES, en aquesta tesi presentem la detecció d'un mini Neptú i una superterra al voltant de les estrelles M LSPM J2116+0234 i GJ 686, respectivament, just fora del límit intern de les respectives zones habitables. Per tal d'evitar la determinació esbiaixada de les característiques dels planetes, hem modelat els senyals planetaris conjuntament amb els provinents de l'activitat estel·lar, els quals hem modelat amb soroll correlat. Els paràmetres orbitals resultants d'aquesta anàlisi corresponen a períodes orbitals de 14.45 d i 15.53 d, i masses mínimes de 12.8 i 6.6 masses terrestres pels planetes LSPM J2116+0234b i GJ 686b, respectivament. El mètode de velocitats radials emprat per a detectar exoplanetes amb CARMENES també permet la detecció de sistemes múltiples. En aquest treball, anunciem el descobriment de 17 nous sistemes, dels quals determinem les òrbites espectrals. La mostra està formada per 15 sistemes binaris (5 amb companyes no detectades) i 3 sistemes triples. Hem determinat que les companyes no detectades de dues de les binàries tenen masses mínimes compatibles amb una nana marró, i demostrem que un sistema binari està format per una nana blanca i una estrella M. Un anàlisi conjunt de velocitats radials i astrometria ens ha permès determinar les masses d'un sistema binari, el qual esdevé un dels sistemes més joves amb masses mesurades. Per últim, hem usat fotometria de TESS per a derivar el temps d'eclipsi de 16 binàries eclipsants excèntriques. Mitjançant l'anàlisi de l'evolució de les diferències entre el temps d'eclipsi primari i secundari amb el temps, hem determinat el moviment apsidal de 10 sistemes, 5 dels quals són mesurats per primer cop. Hem comparat les nostres mesures amb prediccions teòriques obtenint una concordança excel·lent. Hem sigut capaços de mesurar el terme relativista amb prou precisió per a testejar la relativitat general amb aquest mètode per primer cop.
La detección de la primera estrella binaria hace más de 200 años representó el inicio de un nuevo campo en la astrofísica dedicado al estudio de la evolución y las interacciones de estos sistemas, usando como principal herramienta el análisis del movimiento reflejo causado por el cuerpo orbitante. Solo fue cuestión de tiempo que los instrumentos de medida alcanzaran un nivel de precisión suficientemente elevado como para detectar los movimientos inducidos por planetas sobre sus estrellas. El descubrimiento del primer exoplaneta hace casi tres décadas supuso la creación de un seguido de proyectos dedicados a la búsqueda de nuevos mundos, los cuales están produciendo un montón de datos que se están usando con la finalidad de estudiar diferentes propiedades de las estrellas. El objetivo principal de esta tesis es el estudio y caracterización de exoplanetas, estrellas y sistemas estelares mediante el análisis de datos provenientes de proyectos dedicados a la busca de exoplanetas con instrumentos de alta precisión. Este es el caso de los proyectos CARMENES y TESS, que tienen el objetivo de encontrar planetas usando el método de la velocidad radial y la detección de tráficos planetarios, respectivamente, poniendo un énfasis especial en estrellas tipo M. Primeramente, hemos desarrollado un nuevo método para determinar las propiedades de las manchas estelares y de los movimientos convectivos en estrellas M usando la variabilidad inducida por la actividad estelar. En particular, hemos modelado las velocidades radiales cromáticas y la fotometría de la estrella YZ CMi usando el software de modelado de actividad estelar StarSim. El análisis ha revelado la presencia de una gran mancha polar con una temperatura 200 K inferior a la de la estrella, encontrando también que el movimiento convectivo de la estrella podría tener un movimiento inverso al esperado. A partir de un análisis combinado de velocidades radiales antiguas y de CARMENES, en esta tesis presentamos la detección de un mini Neptuno y una supertierra alrededor de las estrellas M LSPM J2116+0234 y GJ 686, respectivamente, justo fuera del límite interno de las respectivas zonas habitables. Para evitar la determinación sesgada de las características de los planetas, hemos modelado las señales planetarias conjuntamente con las provenientes de la actividad estelar, los cuales hemos modelado con ruido correlacionado. Los parámetros orbitales resultantes de este análisis corresponden a periodos orbitales de 14.45 d y 15.53 d, y masas mínimas de 12.8 y 6.6 masas terrestres para los planetas LSPM J2116+0234b y GJ 686b, respectivamente. El método de velocidades radiales empleado para detectar exoplanetas con CARMENES también permite la detección de sistemas múltiples. En este trabajo, anunciamos el descubrimiento de 17 nuevos sistemas, de los cuales determinamos las órbitas espectrales. La muestra está formada por 15 sistemas binarios (5 con compañeras no detectadas) y 3 sistemas triples. Hemos determinado que las compañeras no detectadas de dos de las binarias tienen masas mínimas compatibles con una enana marrón, y demostramos que un sistema binario está formado por una enana blanca y una estrella M. Un análisis conjunto de velocidades radiales y astrometría nos ha permitido determinar las masas de un sistema binario, el cual es uno de los sistemas más jóvenes con masas medidas. Por último, hemos usado fotometría de TESS para determinar el tiempo de eclipse de 16 binarias eclipsantes excéntricas. Mediante el análisis de la evolución de las diferencias entre el tiempo de eclipse primario y secundario con el tiempo, hemos determinado el movimiento apsidal de 10 sistemas, 5 de los cuales son medidos por primera vez. Hemos comparado nuestras medidas con predicciones teóricas obteniendo una concordancia excelente. Hemos sido capaces de medir el término relativista con suficiente precisión para testar la relatividad general con este método por primera vez.
The detection of the first binary star more than 200 years ago opened the door to a whole new field of astrophysics research, devoted to the study of their evolution and mutual interactions employing the analysis of the reflex motion caused by the orbiting companion. It was therefore only a matter of time that the development of astronomical instrumentation reached a precise enough level to detect the motions induced by planetary companions over their host stars. The discovery of the first exoplanet a few decades ago prompted a rapid surge of surveys dedicated to their search, which are providing a huge amount of data that can be also used to study the properties of stars. The main purpose of this thesis is the study and characterization of exoplanets, stars, and stellar systems by analyzing data from high-precision spectroscopic and photometric exoplanet surveys. This is for instance the case of the CARMENES and TESS projects, which aim at the discovery of such objects by means of the radial velocity imprinted on their host star or by the detection of transits, respectively, with particular emphasis on low-mass M-dwarf stars. Firstly, we developed a novel approach to constraint the properties of starspots and convective motions on M dwarfs by using the variability induced by stellar activity. In particular, we modeled chromatic radial velocities and photometric time series of the M-dwarf star YZ CMi using the stellar activity model code StarSim. The results of our analysis revealed the presence of a large polar spot with a temperature 200 K lower than that of the surrounding photosphere, and found that the convective shift of this star may be reversed toward redshift. Based on a combined analysis of CARMENES and archival radial velocities, we present in this thesis the detection of a mini-Neptune and a super-Earth around the M-dwarf stars LSPM J2116+0234 and GJ 686, respectively, just outside the inner edge of their habitable zones. To avoid determining biased parameters due to the contamination from stellar activity, the planetary signals were jointly modeled with a correlated noise model describing stellar variability. The derived orbital parameters resulted in orbital periods of 14.45 d and 15.53 d, and minimum masses of 12.8 and 6.6 Earth masses for LSPM J2116+0234b and GJ 686b, respectively. The radial velocity method used to detect exoplanets with CARMENES is also yielding multiple stellar systems as a by-product. In this work, we report on the discovery of 17 new multiple systems, for which we determined their spectroscopic orbits. The sample is composed of 15 binary systems (5 with undetected companions) and 2 triple systems. We determined that the unseen companions of two of the binaries have minimum masses compatible with a brown dwarf, and we demonstrated that one of the systems is an M-dwarf--white dwarf binary. We also found one of the youngest binary systems with measured masses by analysing both radial velocities and astrometric measurements. Finally, we used TESS photometry to derive eclipse timings for 16 well-studied eccentric eclipsing binaries. We analyzed the change in the difference between primary and secondary eclipse timings over time to determine the apsidal motion rate of 10 of the systems in the sample, 5 of which are measured for the first time. We compared the measured values with theoretical predictions, obtaining an excellent agreement. We were able to measure the general relativistic.
Universitat Autònoma de Barcelona. Programa de Doctorat en Física

Context. Radial velocity and transit methods are effective for the study of short orbital period exoplanets but they hardly probe objects at large separations for which direct imaging can be used. Aims. We carried out the international deep planet survey of 292 young nearby stars to search for giant exoplanets and determine their frequency. Methods. We developed a pipeline for a uniform processing of all the data that we have recorded with NIRC2/Keck II, NIRI/Gemini North, NICI/Gemini South, and NACO/VLT for 14 yr. The pipeline first applies cosmetic corrections and then reduces the speckle intensity to enhance the contrast in the images. Results. The main result of the international deep planet survey is the discovery of the HR8799 exoplanets. We also detected 59 visual multiple systems including 16 new binary stars and 2 new triple stellar systems, as well as 2279 point-like sources. We used Monte Carlo simulations and the Bayesian theorem to determine that 1.05(-0.70)(+2.80)% of stars harbor at least one giant planet between 0.5 and 14 MJ and between 20 and 300AU. This result is obtained assuming uniform distributions of planet masses and semi-major axes. If we consider power law distributions as measured for close-in planets instead, the derived frequency is 2.30(-1.55)(+5.95)%, recalling the strong impact of assumptions on Monte Carlo output distributions. We also find no evidence that the derived frequency depends on the mass of the hosting star, whereas it does for close-in planets. Conclusions. The international deep planet survey provides a database of confirmed background sources that may be useful for other exoplanet direct imaging surveys. It also puts new constraints on the number of stars with at least one giant planet reducing by a factor of two the frequencies derived by almost all previous works.

Ultrafast optical signal processing, which shares the same fundamental principles of electrical signal processing, can realize numerous important functionalities required in both academic research and industry. Due to the extremely fast processing speed, all-optical signal processing and pulse shaping have been widely used in ultrafast telecommunication networks, photonically-assisted RFlmicro-meter waveform generation, microscopy, biophotonics, and studies on transient and nonlinear properties of atoms and molecules. In this thesis, we investigate two types of optical spectrally-periodic (SP) filters that can be fabricated on planar lightwave circuits (PLC) to perform pulse repetition rate multiplication (PRRM) and arbitrary optical waveform generation (AOWG).
First, we present a direct temporal domain approach for PRRM using SP filters. We show that the repetition rate of an input pulse train can be multiplied by a factor N using an optical filter with a free spectral range that does not need to be constrained to an integer multiple of N. Furthermore, the amplitude of each individual output pulse can be manipulated separately to form an arbitrary envelope at the output by optimizing the impulse response of the filter.
Next, we use lattice-form Mach-Zehnder interferometers (LF-MZI) to implement the temporal domain approach for PRRM. The simulation results show that PRRM with uniform profiles, binary-code profiles and triangular profiles can be achieved. Three silica based LF-MZIs are designed and fabricated, which incorporate multi-mode interference (MMI) couplers and phase shifters. The experimental results show that 40 GHz pulse trains with a uniform envelope pattern, a binary code pattern "1011" and a binary code pattern "1101" are generated from a 10 GHz input pulse train.
Finally, we investigate 2D ring resonator arrays (RRA) for ultraf ast optical signal processing. We design 2D RRAs to generate a pair of pulse trains with different binary-code patterns simultaneously from a single pulse train at a low repetition rate. We also design 2D RRAs for AOWG using the modified direct temporal domain approach. To demonstrate the approach, we provide numerical examples to illustrate the generation of two very different waveforms (square waveform and triangular waveform) from the same hyperbolic secant input pulse train. This powerful technique based on SP filters can be very useful for ultrafast optical signal processing and pulse shaping.

This thesis focuses on qualitative and quantitative aspects of some nonlinear PDEs arising in optimal control and differential games, ranging from regularity issues to maximum principles. More precisely, it is concerned with the analysis of some fully nonlinear second order degenerate PDEs over Hörmander vector fields that can be written in Hamilton-Jacobi-Bellman and Isaacs form and those arising in the recent theory of Mean Field Games, where the prototype model is described by a coupled system of PDEs involving a backward Hamilton-Jacobi and a forward Fokker-Planck equation. The thesis is divided in three parts. The first part is devoted to analyze strong maximum principles for fully nonlinear second order degenerate PDEs structured on Hörmander vector fields, having as a particular example fully nonlinear subelliptic PDEs on Carnot groups. These results are achieved by introducing a notion of subunit vector field for these nonlinear degenerate operators in the spirit of the seminal works on linear equations. As a byproduct, we then prove some new strong comparison principles for equations that can be written in Hamilton-Jacobi-Bellman form and Liouville theorems for some second order fully nonlinear degenerate PDEs. The second part of the thesis deals with time-dependent fractional Mean Field Game systems. These equations arise when the dynamics of the average player is described by a stable Lévy process to which corresponds a fractional Laplacian as diffusion operator. More precisely, we establish existence and uniqueness of solutions to such systems of PDEs with regularizing coupling among the equations for every order of the fractional Laplacian $sin(0,1)$. The existence of solutions is addressed via the vanishing viscosity method and we prove that in the subcritical regime the equations are satisfied in classical sense, while if $sleq1/2$ we find weak energy solutions. To this aim, we develop an appropriate functional setting based on parabolic Bessel potential spaces. We finally show uniqueness of solutions both under the Lasry-Lions monotonicity condition and for short time horizons. The last part focuses on the regularizing effect of evolutive Hamilton-Jacobi equations with Hamiltonian having superlinear growth in the gradient and unbounded right-hand side. In particular, the analysis is performed both for viscous Hamilton-Jacobi equations and its fractional counterpart in the subcritical regime via a duality method. The results are accomplished exploiting the regularity of solutions to Fokker-Planck-type PDEs with rough velocity fields in parabolic Sobolev and Bessel potential spaces respectively.

Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society, 2018
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 119-124).
Anecdotes that Millennials are fundamentally different from prior generations are prevalent in the American media. One claim often repeated is that Millennials, happy to rely on public transit or ride-hailing, will not purchase personal vehicles. This claim has the potential to both upset the economy and to reduce greenhouse gas emissions (GHGs) from transportation. This work explores Millennials' preferences for personal vehicles from a quantitative approach utilizing data from the US National Household Travel Survey, Census, and American Community Survey to determine whether observed decreases in vehicle ownership and use by Millennials are due to shifts in preferences, or if demographic changes have altered Millennials' consumer behaviors. I employ econometric techniques to explicitly compare Millennials' vehicle ownership and use to prior generations without the confounding effect of demographic variables using linear regressions, Oaxaca decomposition, and nearest neighbor matching estimators. Additionally, the underlying demographic differences between generations are explored with econometric approaches. The findings from these analyses indicate no significant difference in preferences for vehicle ownership between Millennials and prior generations when confounding variables are controlled, and a preference for higher use in terms of vehicle miles traveled (VMT) by Millennials. The difference in observed vehicle ownership and use arises from both age effects and different underlying demographics. Millennials may be saving the planet with their changing demographics, not because they are fundamentally rejecting personal vehicle ownership and use.
by Elizabeth Anne Murphy.
S.M. in Technology and Policy
S.M.inTechnologyandPolicy Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society

Signal integrity constraints in modern high speed data communication protocols are becoming increasingly stringent. Consumers are demanding faster, more powerful systems with lower power requirements that require faster internal data transfers over longer distances. These two statements are not mutually' compatible because as frequency increases there are increased losses and increased abberations to the data signal from a variety of sources. It, therefore, becomes increasingly difficult to guarantee a receiver will be able to recover the signal. Large system level time domain simulations have been possible for a while, however, the inclusion of an efficient, compatible and accurate time domain transmission line model that responds to the signal in real time has not as yet been possible. Additionally, as the frequency increases, any difference in transmission time between each component of a differential signal will also increase linearly as the period decreases. This signal skew has not as yet presented a problem to signal integrity or loss. However, as the frequency increases there will be increased signal skew which increases mode conversion so less of the signal will be available for recovery using existing skew compensation methodologies. Mode conversion is the process where the energy in a signal is converted from one mode to anotl}er, with a variety of possible causes. The primary cause of mode conversion in this research is signal skew, which causes a potential gradient between the traces forming a differential pair. This allows energy to be coupled and transferred between the copper traces, causing signal asymmetries. This thesis examines high speed planar copper data transmission structures through the use of time and frequency domain modelling. Models for physical loss, reflection and signal skew are created in the time domain using the hardware description language VHDL-AMS while physical loss, reflection, mode conversion and losses to electromagnetic radiation are modelled in the frequency domain using Agilent's Genesys®. There are three main contributions presented in this thesis. The first of which is a signal dependent time domain methodology of calculating skin depths and dielectric conductances in high speed planar data transmission structures The second contribution is a platform independent time domain model of the main loss mechanisms, including signal dependent skin effect and dielectric conductances for implementation in almost any system level mixed signal simulation up to 7 GHz. The third major contribution is a new methodology of approaching and compensating for losses due to mode conversion and EM loss as caused by signal skew in differential microstrip line pairs up to 15 GHz. These methodologies are to be named as skew and EMI management collectively. Finally, there is a set of guidelines for skew management for layout engineers to take into consideration and combine with their existing in depth knowledge of the theory and practice of signal routing at high speed. This will enable high speed planar data transmission structures to transmit signals over longer distances and at higher frequencies whilst preserving signal integrity, thus permitting the continued use of copper for the next generations of products.

Seminario para optar al título de Ingeniero Comercial, Mención Administración
Al momento de evaluar el rendimiento de un país en particular, es normal evaluar una serie de factores. Entre estos, la creación de empleos es uno de los principales a considerar debido a que cuenta con una serie de ventajas dentro de las que se enumeran: Si aumentan los trabajadores, disminuye el número de personas que no recibe ingresos lo que aumenta la probabilidad de disminuir la pobreza. Una disminución en el desempleo implica que más personas se encuentran produciendo para el país lo que podría significar un aumento en la producción de bienes y servicios. Una mayor oferta de trabajo, estimula la competencia entre las personas que demandan empleo, lo que significa una mejor calidad de trabajadores para el futuro. Presentada la importancia que reviste para un país la creación de empleos, se debe analizar quienes son los que están generando puestos de trabajo en nuestro país. Esto permitiría la creación de planes o estrategias para fomentar este tan complejo tópico. Una de las creadoras de puestos de trabajo por excelencia son las nuevas empresas, ya que debido a que están recién comenzando es bastante probable que comiencen a necesitar gente de manera exponencial.

Angiosperms are one of the most dominant groups on Earth, and have fundamentally changed global ecosystem patterns and function. Therefore, unravelling their evolutionary history is key to understanding how the world around us was formed, and how it might change in the future. In this thesis, I use genome-scale data to investigate the evolutionary patterns and timescale of angiosperms at multiple taxonomic levels, ranging from angiosperm-wide to genus-level data sets. I begin by using the largest combination of taxon and gene sampling thus far to provide a novel estimate for the timing of angiosperm origin in the Triassic period. Through a range of sensitivity analyses, I demonstrate that this estimate is robust to many important components of Bayesian molecular dating. I then explore tactics for phylogenomic dating using multiple molecular clocks. I evaluate methods for estimating the number and assignment of molecular clock models, and strategies for partitioning molecular clock models in analyses of multigene data sets. I also demonstrate the importance of critically evaluating the precision in age estimates from molecular dating analyses. Finally, I assess the utility of plastid data sets for resolving challenging phylogenetic relationships, focusing on Pimelea Banks & Sol. ex Gaertn. Through analysis of a multigene data set, sampled from many taxa, I provide an improved phylogeny for Pimelea and its close relatives. I then generate a plastome-scale data set for a representative sample of species to further refine the Pimelea phylogeny, and characterise discordant phylogenetic signals within their chloroplast genomes. The work in this thesis demonstrates the power of genome- scale data to address challenging phylogenetic questions, and the importance of critical evaluation of both methods and results. Future progress in our understanding of angiosperm evolution will depend on broader and denser taxon sampling, and the development of improved phylogenetic methods.

In spite of the stablility (lack of reactivity) of diamond powder, I have developed a method for tethering alkyl chains and polymers to deuterium/hydrogen-terminated diamond. One method is through ether linkages via thermolysis of di-tert-amyl peroxide (DTAP). This reaction with DTAP has also been applied to grow polymers on the diamond surface. The other method is atom transfer radical polymerization (ATRP), which was applied to grow polystyrene at the surface of diamond. Both polystyrene-modified diamond and sulfonated polystyrene-modified diamond can be prepared by either method, and can be used for solid phase extraction. Diamond stationary phases are stable under basic conditions, which is not the case for silica-based stationary phases. Surface characterization was performed by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and diffuse reflectance Fourier transform infrared spectroscopy (DRIFT). While the main focus of my graduate research has been the surface modification of diamond, I also describe other projects on which I have worked. The use of radical-based processes for modifying diamond is related to a different radical-based synthesis of monolayers or polymers I performed by scribing silicon (Siscr). After preparation of homogeneous olefin-terminated monolayers on scribed silicon made from 1,9-decadiene and chemisorption of Grubbs' catalyst, ring-opening metathesis polymerization (ROMP) of norbornene was demonstrated. These surfaces were characterized by XPS and ToF-SIMS. I also investigated the extent of PDMS oligomers transfer onto different surfaces with a wide range of hydrophobicities, using an uninked, unpatterned PDMS stamp. The effect of surface free energy on PDMS transfer in microcontact printing was investigated and the relationship between the amount of PDMS in ToF-SIMS spectra and the surface tensions of initial surfaces was revealed. Therefore, PDMS transfer can be applied as a probe of surface free energies using ToF-SIMS, where PDMS preferentially transfers onto more hydrophilic surface features during stamping, with little transfer onto very hydrophobic surface features. In much of my thesis work, I performed multivariate analysis of my data, especially of my ToF-SIMS data. Such chemometrics methods include principle components analysis (PCA), partial least squares (PLS) cluster analysis, and multivariate curve resolution (MCR). I also applied these tools to analyze electrospray ionization (ESI) mass spectrometry data from a lipidomics study.

Demand for Data Transfer between computers has increased ever since the introduction of Personal Computers (PC). Data Communicating on the Personal Computer is much more productive as it is an intelligent terminal that can connect to various hosts on the same I/O hardware circuit as well as execute processes on its own as an isolated system. Yet, the PC on its own is useless for data communication. It requires a hardware interface circuit and software for controlling the handshaking signals and setting up communication parameters. Often the data is distorted due to noise in the line. Such transmission errors are imbedded in the data and require careful filtering. The thesis deals with the development of a Data Acquisition system that collects real time load and weather data and stores them as historical database for use in a load forecast algorithm in a load management system. A filtering technique has been developed here that checks for transmission errors in the raw data. The microcomputers used in this development are the IBM PC/XT and the AT&T 3B2 supermicro computer.
Master of Science

Les membranes lipidiques constituent des matériaux très particuliers: d'une part, elles sont très peu résistantes aux étirements microscopiques; d'autre part elles sont extrêmement flexibles, présentant des déformations même à des petites échelles. En conséquence, une portion de membrane possède un excès d'aire relatif à l'aire optiquement visible, qu'on appelle l'aire projetée. D'un point de vue mécanique, on peut alors distinguer trois tensions associées aux membranes lipidiques: la tension mécanique effective $\tau$, associée à l'augmentation de l'aire projetée et au lissage des fluctuations; la tension $\sigma$, associée à l'aire microscopique de la membrane et donc non-mesurable, mais couramment utilisée dans les prédictions théoriques; et son équivalent macroscopique mesuré à travers du spectre des fluctuations, $r$. Jusqu'au moment, pour interpréter les données expérimentales, on suppose l'égalité entre ces quantités. Dans cette thèse, nous avons étudié, en utilisant le tenseur des contraintes projeté, si et sous quelles conditions il est justifié d'assumer $\tau = \sigma$. Nous avons étudié trois géométries (planaire, sphérique et cylindrique) et obtenu la relation $\tau \approx \sigma - \sigma_0$, où $\sigma_0$ est une constante qui dépend seulement du plus grand vecteur d'onde de la membrane et de la température. En conséquence, nous concluons que négliger la différence entre $\tau$ et $\sigma$ est justifiable seulement pour des membranes sous grande tension: pour des tensions faibles, il faut considérer des corrections. Nous avons étudié les implications de ce résultat à l'interprétation des expériences d'extraction de nanotubes de membrane. En ce que concerne $r$, nous questionnons une démonstration précédente de son égalité avec $\tau$. Finalement, la fluctuation des forces pour les membranes planes et pour des nanotubes de membranes a été quantifiée pour la première fois.

The performance of distributed key-value stores is usually dependent on its underlying network, and have potential to improve read/write latencies by improving upon the per- formance of the network communication. We explore the potential performance increase by designing an experimental in-network cache based on NetCache in the switch data plane for the distributed key-value store DXRAM, and placing it on a programmable switch that connects the peers in a DXRAM storage cluster. To accomodate DXRAM which uses TCP for its transport protocol, we also design a TCP flow state translator for the cache and implement an experimental version of this cache design. Benchmark runs with the cache show that best-case item read latency for DXRAM is reduced to approximately half and prove the potential performance gain that can be expected once a proper cache is designed and implemented.

Laser scanners in combination with devices for accurate orientation like Coordinate Measuring Machines (CMM) are often used in Geometric Reverse Engineering (GRE) to measure point data. The industrial robot as a device for orientation has relatively low accuracy but the advantage of being numerically controlled, fast, flexible, rather cheap and compatible with industrial environments. It is therefore of interest to investigate if it can be used in this application.

This thesis will describe a measuring system consisting of a laser profile scanner mounted on an industrial robot with a turntable. It will also give an introduction to Geometric Reverse Engineering (GRE) and describe an automatic GRE process using this measuring system. The thesis also presents a detailed accuracy analysis supported by experiments that show how 2D profile data can be used to achieve a higher accuracy than the basic accuracy of the robot. The core topic of the thesis is the investigation of a new technique for planar segmentation. The new method is implemented in the GRE system and compared with an implementation of a more traditional method.

Results from practical experiments show that the new method is much faster while equally accurate or better.

The aim of this thesis is to identify coupling mechanisms for three line microstrip, stripline and microstrip with dielectric overlay structures as either inductive or capacitive, quantify through simulation and measurement the amount of crosstalk to be expected in terms of scattering parameters. A new method of crosstalk suppression is implemented into each three line structure by placing uniformly spaced short circuits down the length of the center transmission line. All structures were simulated over various physical and electrical parameters. Select microstrip structures, shielded and unshielded, were fabricated and measured to validate the effectiveness of the shielding technique. Shielding effectiveness was calculated from the measurements, and their results showed that the isolation between lines was increased by up to 20dB.

Masters of Science
Plant genome analysis is currently experiencing a boost due to reduced costs associated with the development of next generation sequencing technologies. Knowledge on genetic background can be applied to guide targeted plant selection and breeding, and to facilitate natural product discovery and biological engineering. In medicinal plants, secondary metabolites are of particular interest because they often represent the main active ingredients associated with health-promoting qualities. Plant polyphenols are a highly diverse family of aromatic secondary metabolites that act as antimicrobial agents, UV protectants, and insect or herbivore repellents. Most of the genome mining tools developed to understand genetic materials have very seldom addressed secondary metabolite genes and biosynthesis pathways. Little significant research has been conducted to study key enzyme factors that can predict a class of secondary metabolite genes from polyketide synthases. The objectives of this study were twofold: Primarily, it aimed to identify the biological properties of secondary metabolite genes and the selection of a specific gene, naringenin-chalcone synthase or chalcone synthase (CHS). The study hypothesized that data science approaches in mining biological data, particularly secondary metabolite genes, would enable the compulsory disclosure of some aspects of secondary metabolite (SM). Secondarily, the aim was to propose a proof of concept for classifying or predicting plant genes involved in polyphenol biosynthesis from data science techniques and convey these techniques in computational analysis through machine learning algorithms and mathematical and statistical approaches. Three specific challenges experienced while analysing secondary metabolite datasets were: 1) class imbalance, which refers to lack of proportionality among protein sequence classes; 2) high dimensionality, which alludes to a phenomenon feature space that arises when analysing bioinformatics datasets; and 3) the difference in protein sequences lengths, which alludes to a phenomenon that protein sequences have different lengths. Considering these inherent issues, developing precise classification models and statistical models proves a challenge. Therefore, the prerequisite for effective SM plant gene mining is dedicated data science techniques that can collect, prepare and analyse SM genes.

The Mars climate has been explored using two reanalysis datasets based on combining spacecraft observations of temperature and dust with the UK version of the LMD Mars GCM. The semiannual oscillation (SAO) of zonal-mean zonal wind was studied using the existing Mars Analysis Correction Data Assimilation reanalysis during Mars Years (MYs) 24-27. The SAO of zonal-mean zonal wind was shown to exist and extend over a wide range of latitudes. The dynamical driving processes of the SAO in the tropics were investigated, and the forcing due to meridional advection appeared to be the main contributor to the SAO. The study also highlighted some phenomena associated with perturbations of the global circulation during the MY 25 global dust storm (GDS). The meridional advection term was shown to be weaker in the first half of GDS year MY 25 than in the following year, but the forcing due to meridional advection and westward thermal tides both appeared to intensify during the MY 25 GDS. The capabilities of the Mars data assimilation system were also extended in this thesis, 1) to represent dynamic dust lifting and dust transport during the assimilation and 2) to assimilate measurements of the dust vertical distribution. The updated reanalysis was then used to study several major dust events during MY28-29. It proved able to reproduce a southward-moving regional dust storm without the overwhelming assistance of the assimilation. Dust devil lifting was found to at least partly provide the initial pattern of dust of this moving dust storm. The cold anomaly of the cooling zone beneath this dust storm could be as large as ∼ 2 K similar to the magnitude of what was found during the MY 25 GDS. Using the reanalysis, the life cycle of the planet-encircling global dust storm in MY28 was also studied. The Noachis dust storm that occurred just before the MY 28 GDS was found to be the joint result of a travelling Chryse storm, enhanced by dust lifting along its path and local dust lifting in Noachis itself. The adiabatic heating associated with the north polar warming that occurred during MY 28 GDS was up to ∼ 3 times as large as that found during the non-GDS year MY 29. The wind stress dust lifting was shown to in strong correlation with the global average dust loadings, and significantly decreased when the GDS decayed.