To see the other types of publications on this topic, follow the link: PAC.
Dissertations / Theses on the topic 'PAC'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'PAC.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Zirakiza, Brice. "Forêts Aléatoires PAC-Bayésiennes." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/29815/29815.pdf.
Full textAbstract:
Dans ce mémoire de maîtrise, nous présentons dans un premier temps un algorithme
de l'état de l'art appelé Forêts aléatoires introduit par Léo Breiman. Cet algorithme
effectue un vote de majorité uniforme d'arbres de décision construits en utilisant l'algorithme
CART sans élagage. Par après, nous introduisons l'algorithme que nous avons
nommé SORF. L'algorithme SORF s'inspire de l'approche PAC-Bayes, qui pour minimiser
le risque du classificateur de Bayes, minimise le risque du classificateur de Gibbs
avec un régularisateur. Le risque du classificateur de Gibbs constitue en effet, une fonction
convexe bornant supérieurement le risque du classificateur de Bayes. Pour chercher
la distribution qui pourrait être optimale, l'algorithme SORF se réduit à être un simple
programme quadratique minimisant le risque quadratique de Gibbs pour chercher une
distribution Q sur les classificateurs de base qui sont des arbres de la forêt. Les résultasts
empiriques montrent que généralement SORF est presqu'aussi bien performant
que les forêts aléatoires, et que dans certains cas, il peut même mieux performer que
les forêts aléatoires.In this master's thesis, we present at first an algorithm of the state of the art called Random Forests introduced by Léo Breiman. This algorithm construct a uniformly weighted majority vote of decision trees built using the CART algorithm without pruning. Thereafter, we introduce an algorithm that we called SORF. The SORF algorithm is based on the PAC-Bayes approach, which in order to minimize the risk of Bayes classifier, minimizes the risk of the Gibbs classifier with a regularizer. The risk of Gibbs classifier is indeed a convex function which is an upper bound of the risk of Bayes classifier. To find the distribution that would be optimal, the SORF algorithm is reduced to being a simple quadratic program minimizing the quadratic risk of Gibbs classifier to seek a distribution Q of base classifiers which are trees of the forest. Empirical results show that generally SORF is almost as efficient as Random forests, and in some cases, it can even outperform Random forests.
2
Goldberg, Paul W. "PAC-learning geometrical figures." Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/10918.
Full textAbstract:
The thesis studies the following problem: given a set of geometrical figures (such as planar polygons), each one labelled according to whether or not it resembles some 'ideal' figure, find a good approximation to that ideal figure which can be used to classify other figures in the same way. We work within the PAC learning model introduced by Valiant in 1984. Informally, the concepts under consideration are sets of polygons which resemble each other visually. A learning algorithm is given collections of members and non-members of a concept, and its task is to infer a criterion for membership which is consistent with the given examples and which can be used as an accurate classifier of further example polygons. In order to formalise the notion of a concept, we use metrics which measure the extent to which two polygons differ. A concept is assumed to be the set of polygons which are within some distance of some fixed central polygon. In the thesis we work most extensively with the Hausdorff metric. Using the Hausdorff metric we obtain NP-completeness results for several variants of the learning problem. In particular we show that it is hard to find a single geometrical figure which is close to the positive examples but not to the negative examples. This result holds under various assumptions about the specific geometrical figures under consideration. It also holds for several metrics other than the Hausdorff metric. Despite the NP-completeness results mentioned above we have found some encouraging positive results. In particular, we have discovered a general technique for prediction. (Prediction is a less demanding learning model than PAC learning. The goal is to find a polynomial-time algorithm which takes as input a sample of labelled examples and is then able to predict the status of further unlabelled examples in polynomial time).
3
Zirakiza, Brice, and Brice Zirakiza. "Forêts Aléatoires PAC-Bayésiennes." Master's thesis, Université Laval, 2013. http://hdl.handle.net/20.500.11794/24036.
Full textAbstract:
Dans ce mémoire de maîtrise, nous présentons dans un premier temps un algorithme de l'état de l'art appelé Forêts aléatoires introduit par Léo Breiman. Cet algorithme effectue un vote de majorité uniforme d'arbres de décision construits en utilisant l'algorithme CART sans élagage. Par après, nous introduisons l'algorithme que nous avons nommé SORF. L'algorithme SORF s'inspire de l'approche PAC-Bayes, qui pour minimiser le risque du classificateur de Bayes, minimise le risque du classificateur de Gibbs avec un régularisateur. Le risque du classificateur de Gibbs constitue en effet, une fonction convexe bornant supérieurement le risque du classificateur de Bayes. Pour chercher la distribution qui pourrait être optimale, l'algorithme SORF se réduit à être un simple programme quadratique minimisant le risque quadratique de Gibbs pour chercher une distribution Q sur les classificateurs de base qui sont des arbres de la forêt. Les résultasts empiriques montrent que généralement SORF est presqu'aussi bien performant que les forêts aléatoires, et que dans certains cas, il peut même mieux performer que les forêts aléatoires.Dans ce mémoire de maîtrise, nous présentons dans un premier temps un algorithme de l'état de l'art appelé Forêts aléatoires introduit par Léo Breiman. Cet algorithme effectue un vote de majorité uniforme d'arbres de décision construits en utilisant l'algorithme CART sans élagage. Par après, nous introduisons l'algorithme que nous avons nommé SORF. L'algorithme SORF s'inspire de l'approche PAC-Bayes, qui pour minimiser le risque du classificateur de Bayes, minimise le risque du classificateur de Gibbs avec un régularisateur. Le risque du classificateur de Gibbs constitue en effet, une fonction convexe bornant supérieurement le risque du classificateur de Bayes. Pour chercher la distribution qui pourrait être optimale, l'algorithme SORF se réduit à être un simple programme quadratique minimisant le risque quadratique de Gibbs pour chercher une distribution Q sur les classificateurs de base qui sont des arbres de la forêt. Les résultasts empiriques montrent que généralement SORF est presqu'aussi bien performant que les forêts aléatoires, et que dans certains cas, il peut même mieux performer que les forêts aléatoires.
In this master's thesis, we present at first an algorithm of the state of the art called Random Forests introduced by Léo Breiman. This algorithm construct a uniformly weighted majority vote of decision trees built using the CART algorithm without pruning. Thereafter, we introduce an algorithm that we called SORF. The SORF algorithm is based on the PAC-Bayes approach, which in order to minimize the risk of Bayes classifier, minimizes the risk of the Gibbs classifier with a regularizer. The risk of Gibbs classifier is indeed a convex function which is an upper bound of the risk of Bayes classifier. To find the distribution that would be optimal, the SORF algorithm is reduced to being a simple quadratic program minimizing the quadratic risk of Gibbs classifier to seek a distribution Q of base classifiers which are trees of the forest. Empirical results show that generally SORF is almost as efficient as Random forests, and in some cases, it can even outperform Random forests.
In this master's thesis, we present at first an algorithm of the state of the art called Random Forests introduced by Léo Breiman. This algorithm construct a uniformly weighted majority vote of decision trees built using the CART algorithm without pruning. Thereafter, we introduce an algorithm that we called SORF. The SORF algorithm is based on the PAC-Bayes approach, which in order to minimize the risk of Bayes classifier, minimizes the risk of the Gibbs classifier with a regularizer. The risk of Gibbs classifier is indeed a convex function which is an upper bound of the risk of Bayes classifier. To find the distribution that would be optimal, the SORF algorithm is reduced to being a simple quadratic program minimizing the quadratic risk of Gibbs classifier to seek a distribution Q of base classifiers which are trees of the forest. Empirical results show that generally SORF is almost as efficient as Random forests, and in some cases, it can even outperform Random forests.
4
Röder, Jens, and Klaus-Dieter Becker. "PAC spectroscopy and diffusion effects." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-188193.
Full text
5
Echeverría, Oyarzún Felipe. "Renovación urbana plan seccional PAC." Tesis, Universidad de Chile, 2016. http://repositorio.uchile.cl/handle/2250/140043.
Full textAbstract:
Memoria para optar al título de ArquitectoA través de la Historia, Chile ha sufrido cambios enormes en su concepción paradigmática en torno a la creación urbana, adoptando muchas posturas en pro del beneficio común. Sin embargo, así como ha habido etapas favorables y enriquecedoras, hubo otras de crisis y caos, repercutiendo directamente en la realidad actual de la Nación. En la constante búsqueda de mecanismos para paliar el déficit habitacional y nivelar el alto índice de segregación existente, han surgido una infinidad de medidas fuertemente ligadas al imaginario de la época, decantando en diversas realidades tanto positivas como negativas. En el proceso de instauración urbana contemporánea y, en términos de vivienda social, vemos que el paradigma imperante tensiona a la utilización de predios periféricos por los bajos costos de éstos; sin embargo ¿Qué sucede con aquellas comunas de carácter central que se encuentran en situación de riesgo y necesitan intervención por parte del Estado? En este contexto y, a modo de proyecto de titulación, se esgrime el concepto de Renovación Urbana, como herramienta de mejora de barrios, en este caso particular un polígono de la comuna de Pedro Aguirre Cerda. Así, se busca comprender la interrelación de factores que determinarían favorablemente la concepción de vivienda, como punto de partida para la implementación en la creación futura de Vivienda Social de calidad.
6
Röder, Jens, and Klaus-Dieter Becker. "PAC spectroscopy and diffusion effects." Diffusion fundamentals 12 (2010) 92, 2010. https://ul.qucosa.de/id/qucosa%3A13910.
Full text
7
Samohvalov, Veaceslav. "PAC investigations of ferromagnetic spinel semiconductors." Doctoral thesis, [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968962777.
Full text
8
Samohvalov, Veaceslav. "PAC investigations of ferromagnetic spinel semiconductors." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2009. http://nbn-resolving.de/urn:nbn:de:swb:105-4827279.
Full textAbstract:
The ternary spinel-type compounds CdCr2Se4, CdCr2S4, HgCr2Se4, and CuCr2Se4 with Cr as transition metal form a special group of ferromagnetic semiconductors with Curie temperatures up to 430 K. They have particular perspectives in spintronics due to the coexistence of semiconducting and ferromagnetic properties. In this work the ferromagnetic semiconductors were investigated by the hyperfine interactions of implanted nuclear probes using the PAC (perturbed angular correlations) spectroscopy. In such compounds both magnetic hyperfine fields (Bhf) and electric field gradients (efg) allow a detailed study of the behavior of probes, which can additionally represent essential doping atoms in these substances. Besides the popular 111In(111Cd), also 111mCd, 111Ag(111Cd), 77Br(77Se), 117Cd(117In), 199mHg, and 100Pd(100Rh) probes were used exploiting the unique possibilities at the ISOLDE on-line separator and implanter (CERN, Geneva, Switzerland). The main objective of these investigations was to examine the lattice site occupation and the behavior of the implanted probes. In addition, the experimental hyperfine fields were used as test quantities for modern ab initio calculations of the electronic and spin structure (WIEN97).
9
Lacasse, Alexandre. "Bornes PAC-Bayes et algorithmes d'apprentissage." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27635/27635.pdf.
Full textAbstract:
L’objet principale de cette thèse est l’étude théorique et la conception d’algorithmes
d’apprentissage concevant des classificateurs par vote de majorité. En particulier, nous
présentons un théorème PAC-Bayes s’appliquant pour borner, entre autres, la variance
de la perte de Gibbs (en plus de son espérance). Nous déduisons de ce théorème une
borne du risque du vote de majorité plus serrée que la fameuse borne basée sur le risque
de Gibbs. Nous présentons également un théorème permettant de borner le risque associé
à des fonctions de perte générale. À partir de ce théorème, nous concevons des
algorithmes d’apprentissage construisant des classificateurs par vote de majorité pondérés
par une distribution minimisant une borne sur les risques associés aux fonctions de
perte linéaire, quadratique, exponentielle, ainsi qu’à la fonction de perte du classificateur
de Gibbs à piges multiples. Certains de ces algorithmes se comparent favorablement
avec AdaBoost.The main purpose of this thesis is the theoretical study and the design of learning algorithms returning majority-vote classifiers. In particular, we present a PAC-Bayes theorem allowing us to bound the variance of the Gibbs’ loss (not only its expectation). We deduce from this theorem a bound on the risk of a majority vote tighter than the famous bound based on the Gibbs’ risk. We also present a theorem that allows to bound the risk associated with general loss functions. From this theorem, we design learning algorithms building weighted majority vote classifiers minimizing a bound on the risk associated with the following loss functions : linear, quadratic and exponential. Also, we present algorithms based on the randomized majority vote. Some of these algorithms compare favorably with AdaBoost.
10
Audibert, Jean-Yves. "PAC-Bayesian aggregation and multi-armed bandits." Habilitation à diriger des recherches, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00843972.
Full textAbstract:
This habilitation thesis presents several contributions to (1) the PAC-Bayesian analysis of statistical learning, (2) the three aggregation problems: given d functions, how to predict as well as (i) the best of these d functions (model selection type aggregation), (ii) the best convex combination of these d functions, (iii) the best linear combination of these d functions, (3) the multi-armed bandit problems.
11
Daltrini, Beatriz Mascia 1947. "Metodologia para implementação de sistemas PAC reconfiguraveis." [s.n.], 1986. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260438.
Full textAbstract:
Orientador: Marcio Luiz de Andrade NettoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica
Made available in DSpace on 2018-07-14T17:52:53Z (GMT). No. of bitstreams: 1 Daltrini_BeatrizMascia_D.pdf: 4918108 bytes, checksum: 8761ae2c2e1be49150d170d4f61bc731 (MD5) Previous issue date: 1986
Resumo: Este trabalho aborda dois itens distintos porem interrelacionados. O primeiro é uma proposta de metodologia para implementação de Sistemas PAC reconfiguraveis. O segundo refere-se com o fato de capacitar este Sistema PAC com caracteristicas que possibilitem a execução de comandos em paralelo, permitindo que um processamento de longa duração seja executado como tarefa de fundo, enquanto o usuário trabalha por exemplo, em uma tarefa interativa...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital
Abstract: Not informed.
Doutorado
Doutor em Engenharia Elétrica
12
Mai, The Tien. "PAC-Bayesian estimation of low-rank matrices." Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLG001.
Full textAbstract:
Les deux premi`eres parties de cette th`ese 'etudient respectivement des estimateurs pseudo-bay'esiens dans les probl`emes de compl'etion de matrices, et de tomographie quantique. Dans chaque probl`eme, on propose une loi a priori qui induit des matrices de faible rang. On 'etudie les performances statistiques: dans chacun des deux cas, on prouve des vitesses de convergence pour nos estimateurs. Notre analyse repose essentiellement sur des in'egalit'es PAC-Bay'esiennes. On propose aussi un algorithme MCMC pour impl'ementer notre estimateur. On teste ensuite ses performances sur des donn'ees simul'ees, et r'eelles. La derni`ere partie de la th`ese 'etudie le probl`eme de lifelong learning (que l'on peut traduire par apprentissage au long cours), o`u de l'information est conserv'ee et transf'er'ee d'un probl`eme d'apprentissage `a un autre. Nous proposons une formalisation de ce probl`eme dans un contexte de pr'ediction s'equentielle. Nous proposons un m'eta-algorithme pour le transfert d'information, qui repose sur l'agr'egation `a poids exponentiels. On prouve une borne sur le regret de cette m'ethode. Un avantage important de notre analyse est qu'elle ne requiert aucune hypoth`ese sur la forme des algorithmes d'apprentissages utilis'es `a l'int'erieur de chaque probl`eme. On termine cette partie par l''etude de quelques exemples: cas d'un nombre fini de pr'edicteurs, apprentissage d'une direction r'ev'elatrice, et apprentissage d'un dictionnaireThe first two parts of the thesis study pseudo-Bayesian estimation for the problem of matrix completion and quantum tomography. A novel low-rank inducing prior distribution is proposed for each problem. The statistical performance is examined: in each case we provide the rate of convergence of the pseudo-Bayesian estimator. Our analysis relies on PAC-Bayesian oracle inequalities. We also propose an MCMC algorithm to compute our estimator. The numerical behavior is tested on simulated and real data sets. The last part of the thesis studies the lifelong learning problem, a scenario of transfer learning, where information is transferred from one learning task to another. We propose an online formalization of the lifelong learning problem. Then, a meta-algorithm is proposed for lifelong learning. It relies on the idea of exponentially weighted aggregation. We provide a regret bound on this strategy. One of the nice points of our analysis is that it makes no assumption on the learning algorithm used within each task. Some applications are studied in details: finite subset of relevant predictors, single index model, dictionary learning
13
Shanian, Sara. "Sample Compressed PAC-Bayesian Bounds and Learning Algorithms." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29037/29037.pdf.
Full textAbstract:
Dans le domaine de la classification, les algorithmes d'apprentissage par compression d'échantillons sont des algorithmes qui utilisent les données d'apprentissage disponibles pour construire l'ensemble de classificateurs possibles.
Si les données appartiennent seulement à un petit sous-espace de l'espace de toutes les données «possibles», ces algorithmes possédent l'intéressante capacité de ne considérer que les classificateurs qui permettent de distinguer les exemples qui appartiennent à notre domaine d'intérêt.
Ceci contraste avec d'autres algorithmes qui doivent considérer l'ensemble des classificateurs avant d'examiner les données d'entraînement. La machine à vecteurs de support (le SVM) est un algorithme d'apprentissage très performant qui peut être considéré comme un algorithme d'apprentissage par compression d'échantillons.
Malgré son succès, le SVM est actuellement limité par le fait que sa fonction de similarité doit être un noyau symétrique semi-défini positif.
Cette limitation rend le SVM difficilement applicable au cas où on désire utiliser une mesure de similarité quelconque.In classification, sample compression algorithms are the algorithms that make use of the available training data to construct the set of possible predictors. If the data belongs to only a small subspace of the space of all "possible" data, such algorithms have the interesting ability of considering only the predictors that distinguish examples in our areas of interest. This is in contrast with non sample compressed algorithms which have to consider the set of predictors before seeing the training data. The Support Vector Machine (SVM) is a very successful learning algorithm that can be considered as a sample-compression learning algorithm. Despite its success, the SVM is currently limited by the fact that its similarity function must be a symmetric positive semi-definite kernel. This limitation by design makes SVM hardly applicable for the cases where one would like to be able to use any similarity measure of input example. PAC-Bayesian theory has been shown to be a good starting point for designing learning algorithms. In this thesis, we propose a PAC-Bayes sample-compression approach to kernel methods that can accommodate any bounded similarity function. We show that the support vector classifier is actually a particular case of sample-compressed classifiers known as majority votes of sample-compressed classifiers. We propose two different groups of PAC-Bayesian risk bounds for majority votes of sample-compressed classifiers. The first group of proposed bounds depends on the KL divergence between the prior and the posterior over the set of sample-compressed classifiers. The second group of proposed bounds has the unusual property of having no KL divergence when the posterior is aligned with the prior in some precise way that we define later in this thesis. Finally, for each bound, we provide a new learning algorithm that consists of finding the predictor that minimizes the bound. The computation times of these algorithms are comparable with algorithms like the SVM. We also empirically show that the proposed algorithms are very competitive with the SVM.
14
Audibert, Jean-Yves. "Théorie statistique de l'apprentissage : une approche PAC-Bayésienne." Paris 6, 2004. http://www.theses.fr/2004PA066003.
Full text
15
Senadheera, Dodamgodage Gihanee Madumalika. "EXISTENCE OF PAC CONCEPT CLASSES OF INCOMPARABLE DEGREES." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2529.
Full textAbstract:
Probably Approximately Correct (PAC) Learning is one of the models used in machine learning. This model was proposed by Valiant in 1984. The work related to this abstract was inspired by the Post’s problem. Post classified computably enumerable (c.e.) sets and
16
Kerns, Avery Elaine. "Pac-Man and the Pack Mentality: A study of the powers of nostalgia and socialization in gaming choice." Ohio University Honors Tutorial College / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1556209334399674.
Full text
17
Dickson, Louise. "The pharmacology and function of central VPAC/PAC receptors." Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/24523.
Full textAbstract:
Standardised [cAMP]i and [Ca2+]i assays (96-well plate) were used to directly compare hVPAC/PAC receptor pharmacology in CHO-K1 cells stably expressing the receptors, with additional studies evaluating cell lines with endogenous receptor expression. A range of peptide agonists were utilised in these studies, including non-selective (e.g. PACAP-27) and classical ligands (e.g. VIP), as well as recently described (e.g. R3P65) and highly selective compounds (e.g. maxadilan). The agonist rank order of potencies were identical between assays for each receptor in all of the cell lines examined, with EC50 values consistently ~ 100 fold lower in the [Ca2+]i assay. The pharmacology of the reportedly selective peptide antagonists PG7-269 (VPAC1), PG99-465 (VPAC2) and M65 (PAC1) was also examined, with these studies identifying complexities in the pharmacology of PG99-465. The standardised assay conditions and the excellent correlation between the [cAMP]i and [Ca2+]i data, underpinned the establishment of an HT [Ca2+]i assay (384-well plate) which was used to identify hVPAC receptor selective ligands from the compound libraries of the Fujisawa Pharmaceutical Company. Approximately 100,000 compounds were tested, with several non-peptides identified as potential ligands. The potency and selectivity of these compounds were subsequently fully characterised using the 96- and 384-well [Ca2+]i assay formats, although none were as potent as the peptides examined in chapter one. In the final section of this thesis, putative roles for VPAC/PAC receptors in the brain were investigated. Firstly, as VIP and PACAP are thought to stimulate the release of cytokines from astrocytes in the brain, VPAC/PAC receptor pharmacology was examined in primary cultures of rat cortical astrocytes (RCA). Receptor characterisation studies ([cAMP]i assays) established that the PAC1 was the predominant VPAC/PAC receptor subtype in RCA, with preliminary studies also showing that VIP and PACAP-27 stimulated the release of the cytokines IL-1β and TNF-α from these cells. In addition, behavioural studies using mice further examined the role of the VPAC2 receptor in the maintenance of circadian activity rhythms.
18
Svensson, Johan. "Influence map based Ms. Pac-Man and Ghost Controller." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2760.
Full textAbstract:
This thesis will cover the use oftheinfluence map technique applied to the retro game Ms. Pac-Man. A game thatis easy to learn but hard to master. The Ms. Pac-Man controller is implemented with five main parameters that alters the behaviour of the controller while the Ghost controller have three parameters. The experimental results of the controllers is explored to using the alterations of the parameters to find its peak of performance. The conclusion from using the influence map for this game shows that you can easy achieve a certain degree of success fairy easily but as with the game itself it is hard to master same goes for developing a sophisticated controller for this game.
19
Franceschetti, Marie-Laure. "Mu transduction in vivo with cryptic Mu pac motifs." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81332.
Full textAbstract:
Mu is a temperate, transposable coliphage with an unusual mode of replication and maturation. Mu is encapsidated linked to host sequences flanking the dispersed, integrated phage genomes. For encapsidation to occur, phage genomes must be recognized and removed from the chromosome. A putative enzyme recognizes the specific pac sequence within Mu left end.The objective of my research is to characterize the influence of selected E. coli sequences on Mu transduction. In transduction the virion prohead is filled up with an important percentage, if not in totality, of host DNA. Cryptic pac sequences are defined as E.coli K12 genomic sequences showing the highest homology with the endogenous Mu pac sequence. Those host sequences could influence Mu packaging process towards transductants rather than "standard" infectious phage particles.
Using ClustralW software, two cryptic pac sequences were identified. Transduction assays with cloned cryptic pac sequences give insight into E.coli intrinsic potential to promote transduction.
20
Germain, Pascal. "Algorithmes d'apprentissage automatique inspirés de la théorie PAC-Bayes." Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26191/26191.pdf.
Full textAbstract:
Dans un premier temps, ce mémoire présente un théorème PAC-Bayes général, duquel il est possible d'obtenir simplement plusieurs bornes PAC-Bayes connues. Ces bornes permettent de calculer une garantie sur le risque d'un classificateur à partir de ses performances sur l'ensemble de données d'entraînement. Par l'interprétation du comportement de deux bornes PAC-Bayes, nous énonçons les caractéristiques propres aux classificateurs qu'elles favorisent. Enfin, une spécialisation de ces bornes à la famille des classificateurs linéaires est détaillée.
Dans un deuxième temps, nous concevons trois nouveaux algorithmes d'apprentissage automatique basés sur la minimisation, par la méthode de descente de gradient conjugué, de l'expression mathématique de diverses formulations des bornes PAC-Bayes. Le dernier algorithme présenté utilise une fraction de l'ensemble d'entraînement pour l'acquisition de connaissances a priori. Ces algorithmes sont aptes à construire des classificateurs exprimés par vote de majorité ainsi que des classificateurs linéaires exprimés implicitement à l'aide de la stratégie du noyau. Finalement, une étude empirique élaborée compare les trois algorithmes entre eux et révèle que certaines versions de ces algorithmes construisent des classificateurs compétitifs avec ceux obtenus par AdaBoost et les SVM.At first, this master thesis presents a general PAC-Bayes theorem, from which we can easily obtain some well-known PAC-Bayes bounds. Those bounds allow us to compute a guarantee on the risk of a classifier from its achievements on the training set. We analyze the behavior of two PAC-Bayes bounds and we determine peculiar characteristics of classifiers favoured by those bounds. Then, we present a specialization of those bounds to the linear classifiers family. Secondly, we conceive three new machine learning algorithms based on the minimization, by conjugate gradient descent, of various mathematical expressions of the PAC-Bayes bounds. The last algorithm uses a part of the training set to capture a priori knowledges. One can use those algorithms to construct majority vote classifiers as well as linear classifiers implicitly represented by the kernel trick. Finally, an elaborated empirical study compares the three algorithms and shows that some versions of those algorithms are competitive with both AdaBoost and SVM.
Inscrit au Tableau d'honneur de la Faculté des études supérieures
21
Liebeschuetz, J. "Conception and perception pac in phage T1 DNA packaging." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380120.
Full text
22
Rocha, Flávio Sobral Martins e. "Indicadores de saneamento básico após os investimentos do PAC." reponame:Repositório Institucional da UnB, 2014. http://repositorio.unb.br/handle/10482/17099.
Full textAbstract:
Dissertação (mestrado)—Universidade de Brasília, Faculdade de Economia, Administração e Contabilidade, Departamento de Economia, 2014.Submitted by Laura Conceição (laurinha.to@gmail.com) on 2014-11-26T19:22:03Z No. of bitstreams: 1 2014_FlavioSobralMartinseRocha.pdf: 410286 bytes, checksum: 7aaf8208f194777eaeea2628e85baaa8 (MD5)
Approved for entry into archive by Guimaraes Jacqueline(jacqueline.guimaraes@bce.unb.br) on 2014-11-27T14:34:17Z (GMT) No. of bitstreams: 1 2014_FlavioSobralMartinseRocha.pdf: 410286 bytes, checksum: 7aaf8208f194777eaeea2628e85baaa8 (MD5)
Made available in DSpace on 2014-11-27T14:34:17Z (GMT). No. of bitstreams: 1 2014_FlavioSobralMartinseRocha.pdf: 410286 bytes, checksum: 7aaf8208f194777eaeea2628e85baaa8 (MD5)
Esta pesquisa tem como um dos propósitos avaliar a efetividade dos gastos federal, estadual e municipal em saneamento. Interessa também avaliar a eficiência antes e após o Programa de Aceleração do Crescimento (PAC), bem como mensurar a ineficiência técnica das unidades federativas (estados) quanto à aplicação dos investimentos. Por meio de uma análise descritiva entre os períodos 2003-2006 e 2008-2011, são avaliados indicadores relativos aos serviços de abastecimento de água e esgotamento sanitário, comparando os valores apresentados em cada período. Com o objetivo de avaliar a ineficiência técnica das unidades em vista dos investimentos no setor, foi proposta a utilização de um indicador sintético de qualidade do saneamento, definido com base na média geométrica entre os percentuais de domicílios com rede geral de abastecimento de água e o percentual daqueles com rede coletora de esgoto, percentual de esgoto tratado em relação ao coletado, e ainda o percentual do aproveitamento da água na rede distribuição. A medida dessa ineficiência técnica foi realizada por intermédio da metodologia de análise de fronteiras estocásticas, de acordo com o proposto por Lee e Schimdt (1993). Os resultados mostraram que as unidades federativas com melhores indicadores de saneamento em 2003 tendem a permanecer nessa condição e que a ineficiência técnica dos estados apresentava-se superior no período de 2007 em diante, correspondente ao do PAC, período em que houve maior aporte de recursos financeiros. Também foi possível demonstrar que estados com municípios com melhores indicadores de gestão tendem a apresentar menores índices de ineficiência técnica e, portanto lidam de forma melhor com a escassez de recursos. ______________________________________________________________________________ ABSTRACT
One of the purposes of this work is to evaluate the effectiveness of federal, state and municipal spending on sanitation and drinking water supply. It also intends to evaluate efficiency before and after the launch of the Growth Acceleration Program (PAC), as well as measuring the inefficiency of the federal units (states) as the implementation of investments. Through a descriptive analysis between the periods 2003-2006 and 2008-2011, water supply and sewage indicators are evaluated by comparing the values presented in each period. In order to evaluate the technical efficiency, it has been used a synthetic indicator, based on the geometric mean between the percentage of households with access to water and the percentage of those with sewage disposal system, and also between the percentage of treated sewage in relation to the total collected and the percentage of water waste. The measure of this inefficiency was accomplished by using the methodology of analysis of stochastic frontiers. The results showed that the federal units with better sanitation indicators in 2003 are likely to remain in that condition and the technical inefficiency was superior from 2007 onwards, corresponding to the PAC, when there were greater financial resources. It was also possible to demonstrate that states with cities with better management indicators tend to have lower levels of inefficiency and, therefore, they deal the lack of resources better.
23
He, Ling. "Disclosure control of confidential data by applying PAC learning theory." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0011440.
Full text
24
Puke, Stephan. "Investitionsplanung für Prozessinnovationen : eine Analyse am Beispiel von PAC-Systemen /." Wiesbaden : DUV, Dt. Univ.-Verl, 1996. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=007062954&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
Full text
25
Van, Huu Tap, Van Tuyen Trinh, and Xuan Hien Dang. "Treatment of leachate by combining PAC and UV/O3 processes." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-99370.
Full textAbstract:
The landfill leachate is commonly treated for non-biodegradable organic matters, ammonia and colour. Experimental investigations using polyaluminium chlorite (PAC) and UV/O3 have been conducted for the determination of optimal pH value, reaction time and PAC concentration for the removal of chemical oxygen demand (COD) and colour. In pre-treatment coagulation stages, the highest COD and colour removal efficiencies were observed at the concentration of PAC ≥ 3,000 mglG1 and pH values between 7 and 8. However, these experiments also indicated significant removal efficiency for PAC starting with concentrations of 1,500 mglG1. The efficiency of COD and colour removal were approximately 30% and 70%, respectively. Similar efficiencies have been observed also during the second treatment stage where UV/O3 processes were used to treat coagulated leachate. After UV/O3 application, the pH of leachate reached the optimum value of 7.5 whereas the highest COD and colour removal efficiency was 55% and 72%, respectively, and the optimal reaction time was achieved after 80 minNước rỉ rác sinh ra từ bãi chôn lấp chất thải rắn cần được xử lý các thành phần chất hữu cơ khó phân hủy sinh học, xử lí amoni và độ màu. Một số kết quả thử nghiệm về xử lý COD và màu của nước rỉ rác bằng việc sử dụng phương pháp keo tụ với PAC và quá trình UV/O3 đã được thực hiện cùng với việc xác định các giá trị pH tối ưu, thời gian phản ứng và nồng độ PAC tối ưu. Hiệu suất xử lý cao nhất đạt được khi nồng độ của PAC ≥ 3.000 mg/l, pH trong khoảng từ 7 đển 8 trong giai đoạn tiền xử lý. Tuy nhiên, hiệu quả loại bỏ COD và màu bắt đầu tăng rõ khi nồng độ PAC từ 1.500 mg/l trở lên. Hiệu quả loại bỏ COD và màu tương ứng là khoảng 30% và 70%. Các giá trị pH này phù hợp cho quá trình phản ứng UV/O3 được sử dụng sau giai đoạn keo tụ. Sau quá trình xử lý bằng hệ UV/O3, pH của nước rỉ rác tối ưu được xác định là 7,5 (hiệu suất xử lý COD và màu cao nhất tương ứng là 55% và 72%), thời gian phản ứng tối ưu là 80 phút
26
Schannep, Allison Joy. "The Super Pac: Political Paradigm Shift for the 21st Century." Thesis, The University of Arizona, 2014. http://hdl.handle.net/10150/321935.
Full text
27
Nilvetti, Fabio. "Controllo delle vibrazioni mediante l'uso di PAC (Programmable Automation Controller)." Doctoral thesis, Universita degli studi di Salerno, 2012. http://hdl.handle.net/10556/368.
Full textAbstract:
2010 - 2011Con l'espressione `Vibration Control' si intende l'insieme delle tecniche e dei dispositivi che consentono di mitigare in modo rapido, a dabile e preciso le vibrazioni di macchine o strutture, dovute al loro stesso funzionamento o a causa di forze esterne. Nella realizzazione dei sistemi di controllo delle vibrazioni assumono oggi primaria rilevanza sul piano tecnico ed economico l'hardware impiegato. Attuatori elettrici e oleodinamici, dispositivi passivi,sensori, convertitori elettronici e unit a di controllo rappresentano una parte fondamentale di tali sistemi e ne influenzano largamente le prestazioni. Il contributo del singolo componente alle prestazioni complessive del controllo è tuttavia valutato compiutamente solo se ci si pone in un'ottica di sistema, nella quale le mutue interazioni tra componenti elettronici, parti meccaniche e algoritmi di controllo trovano la loro corretta sintesi. Nei sistemi di controllo delle vibrazioni, è decisiva la scelta del `controller'. Scopo del presente lavoro e stato appunto quello di sviluppare un sistema di controllo delle vibrazioni che coniughi le diverse esigenze di precisione, determinismo e elevata velocità di servo-aggiornamento, tipiche di un circuito stampato, alle esigenze di flessibilità ed economicità, tipiche delle soluzioni basate su DSP, e alle elevate capacità di calcolo tipiche di un pc. Per far ciò il ruolo di controller e a dato ad un dispositivo PAC (Programmable Automation Controller) basato su tecnologia FPGA (Field Programmable GateArray) che consente di codifcare, in modo rapido, le funzionalit a richieste al controllo su un dispositivo programmabile di tipo hardware e per questo dalle prestazioni paragonabili a quelle di un circuito stampato. With the expression `Vibration Control' refers to the set of techniques and devices that let you mitigate quickly, reliably and accurately the vibrations of machines or structures, due to themselves operation or due to external forces. In the implementation of vibration control systems today assume pri- mary importance, in the technical and economic terms, the hardware used. Electrical and hydraulic actuators, passive devices, sensors, electronic con- verters and control units are a fundamental part of these systems and they greatly a ects on the performance. In systems of vibration control, is decisive the choice of the controller. The purpose of this work was to develop a system of vibration control which combines the various requirements of precision, determinism and high-speed servo-update, typical of a printed circuit board, the exibility and economy typical of solutions based on DSP, and high computing power of a typical PC. To do this, the role of controller is assigned to a device (PAC programma- ble automation controller) based on technology FPGA (Field Programmable Gate Array) which allows to encode, quickly, the required functionalities to the control, on a programmable hardware device and for this with perfor- mance comparable to that of a printed circuit board. [a cura dell'autore]
X n.s.
28
Cosialls, Ubach Andrés Miguel. "Régimen jurídico de la propiedad agraria sujeta a la nueva PAC." Doctoral thesis, Universitat de Lleida, 2009. http://hdl.handle.net/10803/8128.
Full textAbstract:
Aquest treball analitza, en primer lloc, l'evolució de la codificació civilespanyola i, especialment, el tractament del dret de propietat als diversos projectes de
Codi, així com l'evolució doctrinal d'aquest dret. A continuació, s'ocupa d'examinar els
orígens de la codificació rural, amb especial detall dels diversos projectes que la
doctrina científica va aportar a aquest camp. L'autor dedica un interès especial al
projecte de Codi Rural de Manuel Dánvila, que suposa el major esforç codificador de la
matèria. Dánvila va realitzar dues versions del seu Codi Rural, una abans de l'aprovació
del Codi Civil, i una altra, posterior a aquesta aprovació. Mentre que la primera es
citada per la majoria d'autor que tracten del procés codificador, el segon projecte,
adaptat al Codi Civil, passa incògnit als estudis doctrinals. El present treball s'encarrega
de realitzar un anàlisis comparatiu entre aquestos dos projectes sobre el tractament del
dret de propietat, així com l'avaluació dels diferents informes que es van aportar desde
les Juntes Provincials.
Posteriorment, es realitza un anàlisi de la incidència de la funció social a la
propietat agrària mitjançant els diversos textos que la recullen: Constitució de la Segona
República i Lleis de Conreu Forçós, l'obligació de conrear i les lleis franquistes o la
nova definició de la funció social de la propietat agrària a la Llei de Reforma i
Desenvolupament Agrari. Així mateix, s'analitza la seva transcendència a la Constitució
i les lleis autonòmiques sobre reforma i política agrícola.
Un breu capítol per presentar els fonaments de la Política Agrícola Comuna
serveix per introduir el principal marc d'estudi: la propietat agrària especialíssima.
D'aquesta manera, s'estudien els diferents objectes del dret de propietat agrària
(l'explotació agrícola, la finca, els animals i els drets) i s'analitza la implicació de la
PAC sobre aquestos.
Una vegada delimitat l'objecte de la propietat agrària, s'examinen amb
deteniment cadascuna de les facultats dominicals afectades per la regulació de la PAC i,
en especial, de la condicionalitat vinculada al règim de pagament únic. L'estudi de cada
facultat dominical típica ha estat subdividida en les seves diferents manifestacions. Així,
trobem la llibertat d'elecció de l'ús sobre la cosa, la llibertat de transformar la finca o el
deure de conrear-la. Es realitza un anàlisis acurat dels diferents aprofitaments del dret de
propietat agrària afectats per la PAC (v. gr. caça, llenya, pastures o rostollars), així com
d'altres facultats que estan afectades en menor mesura.
En definitiva, el present treball pretén proporcionar un anàlisis sistemàtic de
l'estatut de la propietat agrària sota una nova realitat jurídica com és la Política Agrícola
Comuna.
Este trabajo analiza, en primer lugar, la evolución de la codificación civil
española y, especialmente, el tratamiento del derecho de propiedad en los diferentes
proyectos de Código, así como la evolución doctrinal en el estudio de este derecho. A
continuación, se ocupa de examinar los orígenes de la codificación rural, con especial
detalle de los diferentes proyectos que la doctrina científica aportó a este campo. El
autor dedica especial interés al proyecto de Código Rural de Manuel Dánvila, que
supone el mayor esfuerzo codificador de la materia. Dánvila realizó dos versiones de su
Código Rural, una antes de la aprobación del Código Civil, y otra, posterior a dicha
aprobación. Mientras que la primera es citada por la mayoría de autores que tratan del
proceso codificador, el segundo proyecto, adaptado al Código Civil, pasa incógnito en
los estudios doctrinales. El presente trabajo se encarga de realizar un análisis
comparativo entre estos dos proyectos sobre el tratamiento del derecho de propiedad, así
como la evaluación de los diferentes informes que se aportaron desde Juntas
Provinciales.
Posteriormente, se realiza un análisis de la incidencia de la función social en la
propiedad agraria a través de los distintos textos legales que la recogen: Constitución de
la Segunda República y Leyes de Laboreo Forzoso, la obligación de cultivo y las leyes
franquistas o la nueva definición de la función social de la propiedad agraria en la Ley
de Reforma y Desarrollo Agrario. Asimismo, se analiza su trascendencia en la
Constitución y las leyes autonómicas sobre reforma y política agraria.
Un breve capítulo para sentar las bases sobre la Política Agrícola Común servirá
para introducir el principal marco de estudio: la propiedad agraria especialísima. De esta
manera, se estudian los diferentes objetos del derecho de propiedad agraria (la
explotación agrícola, la finca, los animales y los derechos) para analizar la implicación
de la PAC sobre los mismos.
Una vez delimitado el objeto de la propiedad agraria, se examinan con
profundidad cada una de las facultades dominicales afectadas por la regulación de la
PAC y, en especial, de la condicionalidad vinculada al régimen de pago único. Cada una
de las facultades dominicales típicas ha sido subdividida en sus diferentes
manifestaciones. Así, encontramos la libertad de elección del uso sobre la cosa, la
libertad de transformar la finca o el deber de cultivar. Se realiza un análisis detenido de
los diferentes aprovechamientos del derecho de propiedad afectados por la PAC (v. gr.
caza, leñas, pastos o rastrojeras), así como de otras facultades que vienen afectadas en
menor medida.
En definitiva, el presente trabajo pretende proporcionar un análisis sistemático
del estatuto de la propiedad agraria bajo una nueva realidad jurídica como la Política
Agrícola Común.
The author examines the process of the codification in Spain and, especially, the
treatment of property rights in the various Drafts, as well as the doctrinal developments
concerning the right of ownership. In particular, the author focuses on of Rural
codification and analizes the different drafts elaborated by the scientific literature.
Special attention receives Rural Code drafted by Dánvila which was the most perfect
attempt to codify the issue. Danvila wrote two versons of his Rural Code, before the
enactment of the Civil Code, and another one after it was approved. While the former is
cited by most authors that deal with codification process, the second draft, adapted to
the Civil Code, has not been examined by scholar doctrine. The author carries out a
comparative analysis of the treatment of property rights in these two projects, and
evaluates the reports that were prepared by several Provincial Boards.
Subsequently, the author analyzes the incidence of social function in land
ownership. The following legislation is considered: the Constitution of the Second
Republic and Forced Tilling Laws, the obligation of cultivation during General Franco's
dictatorship or the new definition of the social function of agricultural property in the
Law on Agrarian Reform and Development. Also, he discusses its significance in the
Constitution and in the regional laws on land reform and agricultural policy.
A brief chapter to lay down foundations on the Common Agricultural Policy
serves as introduction to the main aim of the PhD. Thesis: the very special agricultural
property (propiedad agraria especialísima). In this way, the author examines the object
of property right (farm, farm animals and entitlements) and discusses the implication of
the CAP on them.
After defining the object of agricultural property, the author analyses the
owner's powers affected by the CAP legislation and, in particular, of cross-compliance
of the Single Payment Scheme. Each power is subdivided into its various conections.
Thus, we find freedom of choice for use of the thing, freedom to transform the land or
the duty to cultivate. A thorough analysis of the different uses of property rights
affected by the CAP (eg. hunting, pasture, firewood, or stubble) is carried out, as well as
of the other powers that are affected to a lesser extent.
In conclusion, the PhD Thesis aims at providing a systematic analysis of the
status of agricultural property under the new legal reality enshrined in the Common
Agricultural Policy.
29
Leksawasdi, Noppol Biotechnology & Biomolecular Sciences (BABS) UNSW. "Kinetics and modelling of enzymatic process for R-phenylacetylcarbinol (PAC) production." Awarded by:University of New South Wales. Biotechnology and Biomolecular Sciences (BABS), 2004. http://handle.unsw.edu.au/1959.4/20846.
Full textAbstract:
R-phenylacetylcarbinol (PAC) is used as a precursor for production of ephedrine and pseudoephedrine, which are anti-asthmatics and nasal decongestants. PAC is produced from benzaldehyde and pyruvate mediated by pyruvate decarboxylase (PDC). A strain of Rhizopus javanicus was evaluated for its production of PDC. The morphology of R. javanicus was influenced by the degree of aeration/agitation. A relatively high specific PDC activity (328 U decarboxylase g-1 mycelium) was achieved when aeration/agitation were reduced significantly in the latter stages of cultivation. The stability of partially purified PDC and crude extract from R. javanicus were evaluated by examining the enzyme deactivation kinetic in various conditions. R. javanicus PDC was less stable than Candida utilis PDC currently used in our group. A kinetic model for the deactivation of partially purified PDC extracted from C. utilis by benzaldehyde (0?00 mM) in 2.5 M MOPS buffer has been developed. An initial lag period prior to deactivation was found to occur, with first order dependencies of PDC deactivation on exposure time and on benzaldehyde concentration. A mathematical model for the enzymatic biotransformation of PAC and its associated by-products has been developed using a schematic method devised by King and Altman (1956) for deriving the rate equations. The rate equations for substrates, product and by-products have been derived from the patterns for yeast PDC and combined with a deactivation model for PDC from C. utilis. Initial rate and biotransformation studies were applied to refine and validate a mathematical model for PAC production. The rate of PAC formation was directly proportional to the enzyme activity level up to 5.0 U carboligase ml-1. Michaelis-Menten kinetics were determined for the effect of pyruvate concentration on the reaction rate. The effect of benzaldehyde on the rate of PAC production followed the sigmoidal shape of the Monod-Wyman-Changeux (MWC) model. The biotransformation model, which also included a term for PDC inactivation by benzaldehyde, was used to determine the overall rate constants for the formation of PAC, acetaldehyde and acetoin. Implementation of digital pH control for PAC production in a well-stirred organic-aqueous two-phase biotransformation system with 20 mM MOPS and 2.5 M dipropylene glycol (DPG) in aqueous phase resulted in similar level of PAC production [1.01 M (151 g l-1) in an organic phase and 115 mM (17.2 g l-1) in an aqueous phase after 47 h] to the system with a more expensive 2.5 M MOPS buffer.
30
Quezada, Gonzalez Sergio. "LIGG : uma linguagem grafica baseada em grafo para o MER/PAC." [s.n.], 1987. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259442.
Full textAbstract:
Orientador: Leo Pini MagalhãesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica
Made available in DSpace on 2018-07-15T08:34:32Z (GMT). No. of bitstreams: 1 QuezadaGonzalez_Sergio_M.pdf: 8997663 bytes, checksum: f6faf8f30d206a762b95a9b19c40d97e (MD5) Previous issue date: 1987
Resumo: Neste trabalho uma linguagem gráfica baseada grafos (LIGG) para o MER/PAC é proposta. A definição da LIGG é feita através linguagem de especificação de projetos que possui estrutura controle semelhante às oferecidas em linguagens de alto nível. A LIGG permite a definição e manipulação de base de dados no contexto MER/PAC. O sistema de diálogo que a LIGG. Oferece instrumento de comunicação ao usuário, após procedimentos consistência no comando de diálogo, comunica-se com o GERPAC que através do SIGA acessa a base de dados. Os procedimentos que definem a LIGG são apresentados e um exemplo de implementação é desenvolvido
Abstract: In this work, a graphical language based on graphs (LIGG) for the MER/PAC is proposed. The definition of LIGG is done through a project specification language language with a control structure similar to that from high level languages. With LlGG one can define and manipulate a MER/PAC data base. The dialog system supported by LlGG for user communication, after consistency procedures, use the DBMS GERPAC functions that access the data base through the kernel system SIGA
Mestrado
Mestre em Engenharia Elétrica
31
Turner, R. J. "Validation of the parent-adult-child (PAC-D) projective drawing test." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1335538986.
Full text
32
Halluin, Cyrille d'. "Apprentissage PAC par exemples simples : plate-forme d'apprentissage de langages réguliers." Lille 1, 1998. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1998/50376-1998-105.pdf.
Full textAbstract:
L'apprentissage est le processus par lequel un systeme (naturel ou non) acquiert de nouvelles connaissances. L'apprentissage automatique (machine learning) a pour objectif de creer des systemes artificiels ayant cette capacite d'apprendre, c'est-a-dire capable de traiter de nouvelles donnees sans avoir a programmer explicitement ce traitement. Plus precisement, il s'agit de definir des modeles theoriques d'apprentissage formalisant les idees intuitives que l'on a de l'apprentissage naturel, puis de prouver l'apprenabilite de classes de concepts dans de tels modeles. L'objet de cette these est double. Dans un premier temps, nous proposons un nouveau modele theorique d'apprentissage appele modele pacs. Ce modele est base sur le modele pac propose par valiant. Il a pour originalite de favoriser l'utilisation d'exemples simples par rapport a la cible lors de la phase d'apprentissage. Cet assouplissement du modele pac permet de montrer l'apprenabilite de classes non prouvees apprenables dans le modele de valiant (classe des formules dnf, classe des langages k-reversibles). Ensuite, nous presentons la conception et l'implantation d'une bibliotheque generique, appelee
33
Roch, Jean-Louis. "Calcul formel et parallélisme : l'architecture du système PAC et son arithmétique rationnelle." Phd thesis, Grenoble INPG, 1989. http://tel.archives-ouvertes.fr/tel-00334457.
Full textAbstract:
Pac est un système de calcul formel dédié a une machine Mind massivement parallèle. Dans une première partie, l'architecture du système est décrite. Elle est illustrée par une modélisation théorique et pratique de la parallélisation du produit de deux polynômes. Le système Pac est implante sur la machine t40 de Fps (32 processeurs). Dans une deuxième partie, l'arithmétique nodale en précision infinie sur les rationnels est étudiée. Différents algorithmes sont dégagés, notamment pour la multiplication, la division et le pgcd d'entiers de taille quelconque. Une vectorisation de l'arithmétique de base est discutée et expérimentée
34
Long, Rachel May. "The distribution and diversity of PAC-degrading bacteria and key degradative genes." Thesis, University of Exeter, 2008. http://hdl.handle.net/10036/65303.
Full textAbstract:
Petroleum hydrocarbons are the most widespread contaminants in the environment. Interest in the biodegradation of polycyclic aromatic hydrocarbons and compounds (PAHs/PACs) is motivated by their ubiquitous distribution, their low bioavailability, high persistence in soils and their potentially deleterious effects to human health. Identifying the diversity of microorganisms that degrade PAHs/PACs can be utilised in the development of bioremediation techniques. Understanding the mechanisms of bacterial populations to adapt to the presence of pollutants and the extent that lateral transfer of key functional genes occurs, will allow the exploitation of microbial PAC/PAH-degradative capabilities and therefore enhance the successful application of bioremediation strategies. A key aim of this study was to isolate and identify PAC-degrading bacteria for potential use in future bioremediation programmes. A series of PAC enrichments were established under the same experimental conditions from a single sediment sample taken from a highly polluted estuarine site. Distinct microbial community shifts were directly attributable to enrichment with different PAC substrates. The findings of this study demonstrate that five divisions of the Proteobacteria and Actinobacteria can degrade PACs. By determining the precise identity of the PAC-degrading bacteria isolated, and by comparing these with previously published research, this study showed how bacteria with similar PAC degrading capabilities and 16S rRNA signatures are found in similarly polluted environments in geographically very distant locations e.g. China, Italy, Japan and Hawaii. Such a finding suggests that geographical barriers do not limit the distribution of key PAC-degrading bacteria. This is significant when considering the diversity and global distribution of microbes with PAC-degradative capabilities and the potential for utilising these microbial populations in future bioremediation strategies. In the laboratory, enrichment of bacteria able to utilise PAHs has commonly been performed in liquid media, with the PAH dissolved in a carrier solvent. This study found the presence of a carrier solvent significantly affects the resultant microbial population. Although the same sediment sample was used as the bacterial source in all enrichments, different bacterial strains were obtained depending upon the presence of the carrier solvent and the PAH. This is important when considering appropriate methodology for the isolation of PAH-degrading bacteria for future bioremediation programmes. Additionally, the species comprising the resultant population of the enrichment when a carrier solvent was present were similar to previously reported PAH-degrading species. Such a finding necessitates review of previously reported PAH-degrading bacterial species that have been isolated and identified from enrichments using a carrier solvent. Understanding how bacteria acclimatise to environmental pollutants is vital for exploiting these mechanisms within clear up strategies of contaminated sites. Two major lineages of the α subunit of PAH dioxygenases were identified: Actinobacteria and Proteobacteria. Comparison of the α subunit phylogeny with the 16S rRNA phylogeny implies that the PAH-dioxygenases evolved prior to the separation of these phyla or that lateral transfer occurred in the very distant past. No evidence for lateral transfer of the α subunit between the Actinobacteria and Proteobacteria was found in the phylogenetic analyses of this research. Multiple lateral transfer events were inferred between the species of the Actinobacteria and between the classes of the Proteobacteria. The clustering of the taxa within the α subunit phylogeny indicates that lateral transfer of the α subunit gene occurred after the separation of the classes of Proteobacteria and also after the speciation of the γ-Proteobacteria. These findings reveal how bacteria have acclimatised to PAH pollutants through multiple lateral transfer events of a key PAH-degradative gene. This knowledge of the transfer of genetic material will broaden our prospects of exploiting microbial populations.
35
Lownie, Ken (Ken Earl) 1959. "The Pac-Man strategy : roll-up patterns and processes in three industries." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9219.
Full textAbstract:
Thesis (S.M.M.O.T.)--Massachusetts Institute of Technology, Sloan School of Management, Management of Technology Program, 2000.Also available online at the DSpace at MIT website.
"June 2000."
Includes bibliographical references (leaves 74-78).
The history of some U.S. service industries includes a period of rapid consolidation through the acquisition of many firms by one or a few competitors. This is often referred to as a "roll-up", with the designation used both as a verb in referring to the process and as a noun in referring to the company doing the acquiring. Roll-ups have become a well-known phenomenon since at least 1971, when Waste Management Corporation commenced an aggressive roll-up of the North American solid waste industry. In this paper, we look at the roll-up phenomenon closely and identify some of the patterns that characterize the process. We examine the history of three U.S. service industries -- solid waste, funeral homes, and landscape maintenance -each of which has experienced (or is experiencing) rapid consolidation through the roll-up process. In our investigation, we identify common characteristics as well as key differences among the three, and investigate the background of the industry, the market forces that appeared to be driving the industry dynamics at the time the consolidation efforts began, the pattern and processes of consolidation, and the results of the consolidation effort. In doing so, we identify potential industry characteristics and elements of the roll-up process that may have been contributing factors in determining the outcomes. The analysis employs several concepts and frameworks from the corporate strategy literature. Chief among these is Porter's five forces model of industry structure (Porter 1980). Additional concepts used to compare and contrast the three industries and the consolidation of each include minimum efficient scale, economies and diseconomies of scale, and inspection and integration issues related to merger activity (Oster 1999).
S.M.M.O.T.
36
Michailidou, Maria. "Effects of zoledronic acid (ZOL) and paclitaxelon (PAC) angiogenesis in breast cancer." Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487606.
Full textAbstract:
Zoledronic acid (ZOL; Zometa) is a N-bisphosphonate used in the treatment of tumour related bone disease in solid and haematologic malignancies. ZOL also possesses anti-angiogenic properties by interfering with endothelial cell (EC) function, however little is known about the effect of ZOL on microvascular EC similar to tumour EC. Paclitaxel (PAC; Taxo) is a commonly used chemotherapeutic agent that interferes with microtubule assembly, and its antiangiogenic properties remain to be established. ZOL and PAC have also been shown to have a synergistic effect on apoptosis in breast cancer cells when administered sequentially. The effects of ZOL (0-50JJM for 24-72h) and PAC (0-10nM for 24-72h) alone and in combination were investigated on human dermal microvascular (HuDMEC) and/or macrovascular EC (HUVEC) in vitro. This included effects on EC cell death, adhesion onto extracellular matrix components. proliferation. cell cycle. migration. tube formation, cytoskeletal integrity and prenylation of the GTPase Rap1a. Further studies on the effect of ZOL (50-150JJg/kg) and/or PAC (10-30mg/kg) on normal and tumour vasculature in vivo were performed. using the dorsal microvascular circulation chamber (DMC) model. ZOL reduced EC proliferation, accumulation of cells in the S phase. and further inhibited migration tube formation and Rap1 a prenylation. EC apoptosis using flow cytometry or adhesion on components of the extracellular matrix was not affected. PAC interfered with EC tube formation and increased levels of necrosis and proliferation. Combined treatment with ZOL and PAC induced apoptosis and further inhibited tube formation and migration per cell batch. In vivo studies showed that ZOL alone or in combination with PAC did not affect normal arteriole or venule diameter compared to baselin.e diameter (P>O.05). PAC reduced arteriolar diameter (P
37
Seeger, Matthias. "Bayesian Gaussian process models : PAC-Bayesian generalisation error bounds and sparse approximations." Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/321.
Full textAbstract:
Non-parametric models and techniques enjoy a growing popularity in the field of machine learning, and among these Bayesian inference for Gaussian process (GP) models has recently received significant attention. We feel that GP priors should be part of the standard toolbox for constructing models relevant to machine learning in the same way as parametric linear models are, and the results in this thesis help to remove some obstacles on the way towards this goal. In the first main chapter, we provide a distribution-free finite sample bound on the difference between generalisation and empirical (training) error for GP classification methods. While the general theorem (the PAC-Bayesian bound) is not new, we give a much simplified and somewhat generalised derivation and point out the underlying core technique (convex duality) explicitly. Furthermore, the application to GP models is novel (to our knowledge). A central feature of this bound is that its quality depends crucially on task knowledge being encoded faithfully in the model and prior distributions, so there is a mutual benefit between a sharp theoretical guarantee and empirically well-established statistical practices. Extensive simulations on real-world classification tasks indicate an impressive tightness of the bound, in spite of the fact that many previous bounds for related kernel machines fail to give non-trivial guarantees in this practically relevant regime. In the second main chapter, sparse approximations are developed to address the problem of the unfavourable scaling of most GP techniques with large training sets. Due to its high importance in practice, this problem has received a lot of attention recently. We demonstrate the tractability and usefulness of simple greedy forward selection with information-theoretic criteria previously used in active learning (or sequential design) and develop generic schemes for automatic model selection with many (hyper)parameters. We suggest two new generic schemes and evaluate some of their variants on large real-world classification and regression tasks. These schemes and their underlying principles (which are clearly stated and analysed) can be applied to obtain sparse approximations for a wide regime of GP models far beyond the special cases we studied here.
38
Macedo, Maxsuel de Moura. "Fluidez territorial e log?stica: o PAC no Rio Grande do Norte." Universidade Federal do Rio Grande do Norte, 2014. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18975.
Full textAbstract:
Made available in DSpace on 2015-03-13T17:10:58Z (GMT). No. of bitstreams: 1
MaxsuelMM_DISSERT.pdf: 4624416 bytes, checksum: 0490a56bd282fc3dc15d7c3612fc0ede (MD5)
Previous issue date: 2014-03-28Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The state is responsible for creating regulatory and infrastructural conditions in a determined territory. These actions generate macrodynamics, however, in some cases they show selective and restricted, as in the case concerning the transportation sector. The actions of the Brazilian government aimed at territorial fluidity nowadays are evidenced especially by the Growth Acceleration Program (PAC). The PAC in the axes allocated to the transport sector, called logistics, which in turn appears as a pressing necessity and as an ideology of the current period. Therefore, within this context of territorial transformations resulting from this program we situate our work that aims to understand how the actions of the State implemented and planned under the PAC are configuring or can configure the brazilian territorial logistics, particularly in the state of Rio Grande do Norte
O Estado ? respons?vel por criar condi??es normativas e infraestruturais em um determinado territ?rio. Essas a??es geram macrodin?micas, contudo, em alguns casos elas se mostram seletivas e restritas, como no caso das concernentes ao setor de transporte. As a??es do Estado brasileiro destinadas a fluidez territorial na atualidade s?o consubstanciadas, especialmente, pelo Programa de Acelera??o do Crescimento (PAC). O PAC nos eixos destinados ao setor de transporte ? batizado de log?stica, que por sua vez, se apresenta como uma necessidade premente e como uma ideologia do atual per?odo. Portanto, dentro desse contexto de transforma??es territoriais advindas com esse programa situamos nosso trabalho, que objetiva compreender como as a??es do Estado concretizadas e planejadas no ?mbito do PAC est?o configurando ou podem configurar a log?stica territorial brasileira, particularmente, a do estado do Rio Grande do Norte
39
Lima, Júnior Guilherme Ferreira de. "Os impactos do PAC no crescimento econômico regional: uma abordagem PósKeynesiana multissetorial." Universidade Federal de Uberlândia, 2017. https://repositorio.ufu.br/handle/123456789/18159.
Full textAbstract:
Conselho Nacional de Desenvolvimento Científico e TecnológicoO objetivo desta dissertação é analisar os efeitos dos investimentos em infraestrutura rodoviária para o comércio exterior com os BRICS, bem como seus efeitos sobre o crescimento per capita dos estados brasileiros. Para tanto, constrói-se um modelo multissetorial de crescimento conduzido pelas exportações que será utilizado como referência na análise empírica, que avança em termos matemáticos com a inclusão dos investimentos em infraestrutura impactando o comércio entre os países. A metodologia empregada neste trabalho é a de dados em painel e o período de análise compreende os anos de 2008 a 2013, em função da disponibilidade de dados. Os resultados são categóricos, no sentido de demonstrar que o comércio dos estados brasileiros foram afetados pelos investimentos rodoviários do PAC. As estimações foram realizadas em três recortes: todos os estados; estados do Sul e Sudeste; e com os estados do Nordeste, Norte e Centro-Oeste. Pode-se afirmar, ainda, que as economias dos estados do Sul e Sudeste, que possuem uma melhor infraestrutura, tiveram um impacto positivo dos investimentos do PAC concluídos, enquanto que nas regiões de pior infraestrutura, Norte, Nordeste e Centro-Oeste, os investimentos do PAC tiveram um impacto negativo na renda; regiões com uma infraestrutura deficitária devem sofrer um impacto positivo na renda quando a infraestrutura atingir um nível mínimo de competitividade. Com isso, pode-se destacar que os investimentos do PAC devem ser concluídos e estimulados nas regiões Norte, Nordeste e Centro-Oeste, para melhorar o desempenho econômico dessas regiões.
This dissertation aims to analyze the effects of investments in road infrastructure for foreign trade with the BRICS, as well as their effects on the per capita growth of the Brazilian states. For this, a multisectoral model of export-led growth is constructed, which will be used as a reference in the empirical analysis, which advances in mathematical terms with the inclusion of infrastructure investments impacting trade between countries. The methodology employed in this work is that of panel data and the period of analysis comprises the years 2008 to 2013, due to the availability of data. The results are categorical, in order to demonstrate that the trade of the Brazilian states was affected by the PAC's road investments. The estimates were made in three cuts: all states; Southern and Southeastern states; And with the states of the Northeast, North and Central West. It is also possible to affirm that the economies of the South and Southeast states, which have a better infrastructure, had a positive impact on the investments of the PAC, while in the worst infrastructure regions, North, Northeast and Central West, investments Of the PAC had a negative impact on income; regions with a deficit infrastructure should have a positive impact on income when the infrastructure reaches a minimum level of competitiveness. Thus, it should be noted that PAC investments must be completed and stimulated in the North, Northeast and Central West regions to improve the economic performance of these regions.
Dissertação (Mestrado)
40
Simó, Ramiro Maria Aránzazu. "Les impacts de l'introduction de la conditionnalité des aides de la PAC /." Montpellier : CIHEAM-IAMM, 2008. http://catalogue.bnf.fr/ark:/12148/cb413522993.
Full textAbstract:
Thèse Master of science--Agronomie--Montpellier--Institut agronomique méditerranéen, 2008.CIHEAM = Centre international des hautes études agronomiques méditerranéennes. IAMM = Institut agronomique méditerranéen de Montpellier. En appendice, choix de documents. Bibliogr. p. 73-76. Résumé en français et en anglais.
41
Roch, Jean-Louis Della Dora Jean. "Calcul formel et parallélisme l'architecture du système PAC et son arithmétique rationnelle /." S.l. : Université Grenoble 1, 2008. http://tel.archives-ouvertes.fr/tel-00334457.
Full text
42
Gavin, Gérald Zighed Djamel Abdelkader. "Etude du modèle d'apprentissage Probablement Approximativement Correct (PAC) application aux méthodes d'agrégation /." [S.l.] : [s.n.], 2001. http://theses.univ-lyon2.fr/Theses2001/gavin_g/these.pdf.
Full text
43
Lin, Hau-Kuo, and 林華國. "Development of the Penicillin Acylase(PAC) Enzyme Production Process:Cloning of the pac Gene." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/99902278194415572624.
Full textAbstract:
碩士逢甲大學
化學工程研究所
85
Recombinant DNA technology was applied for the production of an industrial enzyme of penicillin acylase (PAC). The PAC-encoding gene (pac) from an E. coli strain of ATCC11105 was cloned using the PCR technology in this study. We made two clones, pCLL3201 and pCLL2902, containing the pac gene which was suitably expressed in many of the E. coli host strains. The PAC expression level could be greatly enhanced, at more than 3 folds compared to ATCC11105, using an appropriate gene expression system. We also subcloned the pac gene into an expression vector of pTrc99A by making two recombinant plasmids of pTrcPAC3201 and pTrcPAC2902 in which the pac gene expression was under the regulation of the tac promoter system. The PAC enzyme activity was however minimally detected for the two clones, therefore further investigation will be required.
44
Jabbari, Arfaee Shahin. "PAC-learning with label noise." Master's thesis, 2010. http://hdl.handle.net/10048/1645.
Full textAbstract:
One of the main criticisms of previously studied label noise models in the PAC-learning framework is the inability of such models to represent the noise in real world data. In this thesis, we study this problem by introducing a framework for modeling label noise and suggesting four new
label noise models. We prove positive learnability results for these noise models in learning simple concept classes and discuss the difficulty of the problem of learning other interesting concept classes under these new models. In addition, we study the previous general learning algorithm,
called the minimum pn-disagreement strategy, that is used to prove learnability results in the PAC-learning framework both in the absence and presence of noise. Because of limitations of the minimum pn-disagreement strategy, we propose a new general learning algorithm called the minimum
nn-disagreement strategy. Finally, for both minimum pn-disagreement strategy and minimum nn-disagreement strategy, we investigate some properties of label noise models that provide sufficient conditions for the learnability of specific concept classes.
45
Kalina, Petr. "Návrh a implementace systému PAC." Master's thesis, 2008. http://www.nusl.cz/ntk/nusl-288236.
Full textAbstract:
PAC (Picture Archiving and Communication) systems enable for storage and management of digital picture data produced by various modalities on radiological and other hospital departments. An effective implementation of a PAC system has to face number of challenges - how the picture data and corresponding metadata are represented, how are they communicated, how the system integrates with other department or hospital subsystems, how the workflow and basic tasks are managed or how scalability, robustness and reliability is achieved. There are several industrial standards affecting this area - and all of them are quite complex. The aim of this work was to design and implement a PAC system that would be capable of long-term production use at PET center of Na Homolce hospital under existing requirements an limitations and that would be very standardized in respect to the existing industrial standards.
46
Lii, Tsung-Ju, and 李宗儒. "Program Testing with PAC Guarantees." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/24399917859136071034.
Full textAbstract:
碩士國立臺灣大學
電子工程學研究所
104
In this work, we introduce two novel techniques for software testing and model synthesis of sequential programs, the learning-based and the sampling-based techniques. With these two techinques, we hope to diminish the distinctions between software testing and formal verification by providing a statistical guarantee while being scalable. Our learning-based technique is based on learning a regular model of the set of feasible paths in a program, and testing whether this model contains an incorrect behavior. Exact learning algorithms require checking equivalence between the model and the program, which is in general undecidable. Our learning procedure is therefore based on the framework of probably approximately correct (PAC) learning, which uses sampling instead and provides correctness guarantees expressed using the terms error probability and confidence level. In addition, our procedure also outputs the model with the said correctness guarantees. Another technique we propose is the sampling-based approach, which is also based on the guarantees provided by PAC learning. We utilized concolic testers as samplers to obtain samples of execution traces of the program-under-tests, then conclude whether the programs contain feasible error traces, are free from error with PAC guarantee, or are of unknown results due to insufficient computational resources. We implemented the abovementioned two techniques with a prototype called Pac-Man. Furthermore, obtained preliminary experiments show encouraging results, in some cases even outperforming mature software verifiers. As a result, we submitted Pac-Man''s implementation of the sampling-based techinque to participate in Software Verification Competition (SV-COMP) 2016. We ranked 5th in the recursive subcategory, and 4th in the array-reach subcategory. Moreover, we submitted a paper illustrating the learning-based procedure to the International Conference on Software Engineering (ICSE) 2016, and was successfully accepted.
47
ChiLuo, Chih, and 羅之琪. "Performance of Porous Asphalt Concrete (PAC) and Evaluation of Cold-Mix Materials Applied to PAC Maintenance." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/21326122340096408254.
Full text
48
Liaw, Hsiang-An, and 廖祥安. "A Ms. Pac-Man Controller Agent." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/02457105393813870133.
Full textAbstract:
碩士國立中正大學
資訊工程研究所
99
Distributed at North America in 1981, Ms. Pac-Man was the most famous arcade games at that time. Until now, many scholars are still studying artificial intelligence with Ms. Pac-Man. The game requires players’ instant and quick judgments, to command Ms. Pac-Man to escape from the ghosts’ arrest, and to eat up all the pills to achieve higher scores. In conclusion the game is a difficult and challenging one. In this paper we construct a thorough agent system for Ms. Pac-Man, in which we do the screen capture, image processing, image analysis, and then we assign an agent to control the movements of Ms. Pac-Man, in order to improve her performance. To reduce the amount of computation for time saving, we construct only path map and suggest two searching methods with Ms. Pac-Man as the center： 1. Near Distance Search. 2. Far Distance Search. To avoid too much instant calculation and provide answers to quick inquiry, we suggest pre-calculate distance from any single point to single point on the path map. Therefore we use Iterative Deepening DFS (IDS) to construct a distance table with eight directions for Ms. Pac-Man to determine the direction of ghosts. This method has the highest score record of 21,030, with an average of 8,030.
49
Brodag, Thomas. "PAC-Lernen zur Insolvenzvorhersage und Hotspot-Identifikation." Doctoral thesis, 2008. http://hdl.handle.net/11858/00-1735-0000-0006-B3A8-5.
Full text
50
MAI, The Tien. "PAC-Bayesian estimation of low-rank matrices." Thesis, 2017. http://www.theses.fr/2017SACLG001/document.
Full textAbstract:
Les deux premi`eres parties de cette th`ese 'etudient respectivement des estimateurs pseudo-bay'esiens dans les probl`emes de compl'etion de matrices, et de tomographie quantique. Dans chaque probl`eme, on propose une loi a priori qui induit des matrices de faible rang. On 'etudie les performances statistiques: dans chacun des deux cas, on prouve des vitesses de convergence pour nos estimateurs. Notre analyse repose essentiellement sur des in'egalit'es PAC-Bay'esiennes. On propose aussi un algorithme MCMC pour impl'ementer notre estimateur. On teste ensuite ses performances sur des donn'ees simul'ees, et r'eelles. La derni`ere partie de la th`ese 'etudie le probl`eme de lifelong learning (que l'on peut traduire par apprentissage au long cours), o`u de l'information est conserv'ee et transf'er'ee d'un probl`eme d'apprentissage `a un autre. Nous proposons une formalisation de ce probl`eme dans un contexte de pr'ediction s'equentielle. Nous proposons un m'eta-algorithme pour le transfert d'information, qui repose sur l'agr'egation `a poids exponentiels. On prouve une borne sur le regret de cette m'ethode. Un avantage important de notre analyse est qu'elle ne requiert aucune hypoth`ese sur la forme des algorithmes d'apprentissages utilis'es `a l'int'erieur de chaque probl`eme. On termine cette partie par l''etude de quelques exemples: cas d'un nombre fini de pr'edicteurs, apprentissage d'une direction r'ev'elatrice, et apprentissage d'un dictionnaireThe first two parts of the thesis study pseudo-Bayesian estimation for the problem of matrix completion and quantum tomography. A novel low-rank inducing prior distribution is proposed for each problem. The statistical performance is examined: in each case we provide the rate of convergence of the pseudo-Bayesian estimator. Our analysis relies on PAC-Bayesian oracle inequalities. We also propose an MCMC algorithm to compute our estimator. The numerical behavior is tested on simulated and real data sets. The last part of the thesis studies the lifelong learning problem, a scenario of transfer learning, where information is transferred from one learning task to another. We propose an online formalization of the lifelong learning problem. Then, a meta-algorithm is proposed for lifelong learning. It relies on the idea of exponentially weighted aggregation. We provide a regret bound on this strategy. One of the nice points of our analysis is that it makes no assumption on the learning algorithm used within each task. Some applications are studied in details: finite subset of relevant predictors, single index model, dictionary learning