Un inventaire des Tetrany chidae du Brésil a été réalisé dans 15 États ainsi que dans le District Fédéral, avec 550 échantillons de 120 espèces végétales collectés. Des infestations par des acariens tétranychidés ont été confirmées dans 207 de ces échantillons. Vingt-deux espèces appartenant à sept genres de la sous-familles des Bryobiinae et Tetranychinae ont été identifiées chez 58 hôtes différents. Trente-six nouvelles plantes hôtes pour 11 espèces ont été répertoriées au Brésil, en Amérique du sud ou dans le monde. De nouvelles localités ont été enregistrées au Brésil pour quatre tétranychides et une espèce a également été signalée pour la première fois en Amérique du sud. Quatre nouvelles espèces ont été découverte: deux appartenant au genre Oligonychus Berlese et deux appartenant aux genres Monoceronychus McGregor et Schizotetranychus Tragardh. La contribution à la systématique du genre Tetranychus a consisté à analyser conjointement des substuences d´ADN ribosomique (ITS) et mitochondrial (COI) de femelles de T.urticae, T. cinnabarinus (synonyme potentiel de T. urticae) et d'espèces très proches appartenant également au groupe Tetranychus sensu stricto. Cette étude a mis en évidence des incohérences ce qui nous a amené à remettre en question la fiabilité des données moléculaires concernant le groupe Tetranychus s. str. disponibles dans Genbank. Des données sur la variabilité génétique, la phylogénie et la structure de populations de T. urticae au Brésil et dans le monde sont ensuite présentées. Les résultats indiquent la présence significative d'une structuration génétique des populations de T. urticae par rapport à la localisation géographique. L´effet de la plante hôte n´est pas observé. La diversité haplotypique, inférée à partir des ces deux régions du génome (ITS et COI) est plus élevée dans les pays du pourtour méditerranéen. On a constaté la présence de deux haplotypes mitochondriaux (COI) au Brésil, l´un partagé avec la France, l´Espagne et les îles Canaries, et l´autre avec le Japon. / In this study we performed a survey of Tetranychidae mites from Brazil, including 15 States and the Federal District. A total of 550 samples of 120 different plant species were collected. Tetranychid mite infestations were confirmed in 207 samples, and 22 species belonging to seven genera of the Bryobiinae and Tetranychinae subfamilies were identified on 58 different host plants. Thirty-six new hosts were recorded in Brazil, South America and worldwide for eleven species. New localities were registered for four tetranychid genera and a new record to South America was confirmed. Four species were identified as new for science: two belonging to the Oligonychus Berlese genus and two belonging to the Monoceronychus McGregor and Schizotetranychus Tragardh genera. We analyzed and evaluated the identity of 105 Genbank accessions of ITS2 rDNA and 138 COI mtDNA sequences which were deposited as T. urticae and as fourteen other taxa morphologically close ly related to Tetranychus sensu stricto. Among the deposited sequences in the Genbank, numerous cases of apparently mistaken identities were identified in the group Tetranychus s. str., especially between T. urticae, T. cinnabarinus, T. kanzawai and T. truncatus. New sequences of ITS and COI were obtained from individuals collected in Brazil and some localities of the Palearctic Region (France, continental Spain, Canary Islands, Greece, Syria, Tunisia, Poland and Norway plus one from Canada). While significant differences were detected on population genetic structure of the analyzed samples according to the geographic region, any effect of the host plant was observed. Haplotype diversity inferred from both ITS and COI sequences was higher in samples from the Mediterranean basin. ITS sequences obtained from Brazil samples were homogenous, and two COI haplotypes were found, one of them also present in France, Spain and the Canary Islands and the other in Japan.

This thesis presents the search for New Physics in events with four top quarks using the data collected in proton-proton collisions by the ATLAS experiment at the LHC. The dataset corresponds to the one taken during all 2011 at √s = 7 TeV and a part of 2012 at √s = 8 TeV. The analysis focuses on a final state with two leptons (electrons and muons) with the same electric charge. This signature is experimentally favored since the presence of two same-sign leptons in the final state allows to reduce the background coming from Standard Model (SM) processes. The results are interpreted in the context of a low energy effective field theory, which assumes that New Physics at low energy can manifest itself as a four right-handed top contact interaction. In this context, this analysis allows testing a class of beyond-the-SM (BSM) theories which at low energy can manifest in this way. Backgrounds to this search have been estimated using simulated samples and data-driven techniques. Different sources of systematic uncertainties have been also considered. The final selection of events has been optimized by aiming at minimizing the expected upper limit on the four tops production cross-section in case of no signal events found. The signal region is then analyzed by looking for an excess of events with respect to the predicted background. No excess of events has been observed, and the observed upper limit on the four tops production cross-section has been computed. This limit is then translated to an upper limit on the coupling strength C=2 of the model. An upper limit on the four tops production cross-section in the SM has been also computed in the analysis performed at √s = 8 TeV. In addition to the physics analysis of the four tops signal, some studies about the LASER calibration system of the ATLAS Tile calorimeter are presented. In particular, they are related to the photodiodes system used to measure the intensity of the laser light in the LASER system.

Cette thèse a pour but la recherche de Nouvelle Physique dans les événements à quatre quarks top en utilisant les données collectées dans les collisions proton-proton par l'expérience ATLAS au LHC. L'ensemble des données correspond à celui enregistré pendant tout 2011 à √s = 7 TeV et une partie de l'année 2012 à √s = 8 TeV. L'analyse est concentrée sur un état final avec deux leptons (des électrons et des muons) avec la même charge électrique. Cette signature est expérimentalement privilégiée puisque la présence de deux leptons avec le même signe dans l'état final permet de réduire le bruit du fond qui vient des processus du Modèle Standard. Les résultats sont interprétés dans le contexte d'une théorie effective à basse énergie, qui suppose que la Nouvelle Physique peut se manifester à basse énergie comme une interaction de contact à quatre tops droits. Dans ce contexte, cette analyse permet de prouver un type de théorie au delà du Modèle Standard qui, à basse énergie, peut se manifester de cette manière. Les bruits du fond pour cette recherche ont été estimés en utilisant des échantillons simulés et des techniques axées sur les données. Différentes sources d'incertitudes systématiques ont été considérées. La sélection finale des événements a été optimisée en visant à minimiser la limite supérieure attendue sur la section efficace de production des quatre tops si aucun événement de signal n'est trouvé. La région du signal a été ensuite examinée à la recherche d'un excès d'événement en comparaison avec le bruit du fond prévu. Aucun excès d'événement n'a été observé, et la limite supérieure observée sur la section efficace de production de quatre quarks top a été calculée. Ceci a permis de calculer la limite supérieure sur la constante de couplage C=2 du modèle. Une limite supérieure sur la section efficace de production de quatre tops dans le Modèle Standard a été aussi calculée dans l'analyse a √s = 8 TeV. En plus de l'analyse physique du signal de quatre tops, des études concernant le système d'étalonnage LASER du calorimètre Tile ont été présentées. Ces études sont liées au système des photodiodes utilisé pour mesurer l'intensité de la lumière dans le système LASER. / This thesis presents the search for New Physics in events with four top quarks using the data collected in proton-proton collisions by the ATLAS experiment at the LHC. The dataset corresponds to the one taken during all 2011 at √s = 7 TeV and a part of 2012 at √s = 8 TeV. The analysis focuses on a final state with two leptons (electrons and muons) with the same electric charge. This signature is experimentally favored since the presence of two same-sign leptons in the final state allows to reduce the background coming from Standard Model (SM) processes. The results are interpreted in the context of a low energy effective field theory, which assumes that New Physics at low energy can manifest itself as a four right-handed top contact interaction. In this context, this analysis allows testing a class of beyond-the-SM (BSM) theories which at low energy can manifest in this way. Backgrounds to this search have been estimated using simulated samples and data-driven techniques. Different sources of systematic uncertainties have been also considered. The final selection of events has been optimized by aiming at minimizing the expected upper limit on the four tops production cross-section in case of no signal events found. The signal region is then analyzed by looking for an excess of events with respect to the predicted background. No excess of events has been observed, and the observed upper limit on the four tops production cross-section has been computed. This limit is then translated to an upper limit on the coupling strength C=2 of the model. An upper limit on the four tops production cross-section in the SM has been also computed in the analysis performed at √s = 8 TeV. In addition to the physics analysis of the four tops signal, some studies about the LASER calibration system of the ATLAS Tile calorimeter are presented. In particular, they are related to the photodiodes system used to measure the intensity of the laser light in the LASER system.

The desire to enhance and make ourselves better is not a new one and it has continued to intrigue throughout the ages. Individuals have continued to seek ways to improve and enhance their well-being for example through nutrition, physical exercise, education and so on. Crucial to this improvement of their well-being is improving their ability to remember. Hence, people interested in improving their well-being, are often interested in memory as well. The rationale being that memory is crucial to our well-being. The desire to improve one’s memory then is almost certainly as old as the desire to improve one’s well-being. Traditionally, people have used different means in an attempt to enhance their memories: for example in learning through storytelling, studying, and apprenticeship. In remembering through practices like mnemonics, repetition, singing, and drumming. In retaining, storing and consolidating memories through nutrition and stimulants like coffee to help keep awake; and by external aids like notepads and computers. In forgetting through rituals and rites. Recent scientific advances in biotechnology, nanotechnology, molecular biology, neuroscience, and information technologies, present a wide variety of technologies to enhance many different aspects of human functioning. Thus, some commentators have identified human enhancement as central and one of the most fascinating subject in bioethics in the last two decades. Within, this period, most of the commentators have addressed the Ethical, Social, Legal and Policy (ESLP) issues in human enhancements as a whole as opposed to specific enhancements. However, this is problematic and recently various commentators have found this to be deficient and called for a contextualized case-by-case analysis to human enhancements for example genetic enhancement, moral enhancement, and in my case memory enhancement (ME). The rationale being that the reasons for accepting/rejecting a particular enhancement vary depending on the enhancement itself. Given this enormous variation, moral and legal generalizations about all enhancement processes and technologies are unwise and they should instead be evaluated individually. Taking this as a point of departure, this research will focus specifically on making a case for ME and in doing so assessing the ESLP implications arising from ME. My analysis will draw on the already existing literature for and against enhancement, especially in part two of this thesis; but it will be novel in providing a much more in-depth analysis of ME. From this perspective, I will contribute to the ME debate through two reviews that address the question how we enhance the memory, and through four original papers discussed in part three of this thesis, where I examine and evaluate critically specific ESLP issues that arise with the use of ME. In the conclusion, I will amalgamate all my contribution to the ME debate and suggest the future direction for the ME debate.