<p>This thesis reports the results of a twofold study on the recently proposed phenomenon of &lsquo / stellar pulsations&rsquo / in young brown dwarfs by the seminal study of Palla and Baraffe (2005) (PB05, thereafter). The PB05 study presents results of a non-adiabatic linear stability analysis showing that young brown dwarfs should become pulsationally unstable during the deuterium burning phase of their evolution.</p>

Les naines brunes sont des objets astronomiques de faible masse ( 0.012 - 0.075 M_Sun ) et de basse température ( T < 3,500 K ). Bien qu’elles se forment comme des étoiles, c’est-à-dire par l’effondrement d’un nuage de gaz moléculaire, les naines brunes n’ont pas une masse suffisante pour entretenir des réactions de fusion nucléaire en leur coeur. Les naines brunes relativement chaudes (type L) sont recouvertes de nuages de poussière mais ces derniers disparaissent progressivement de l’atmosphère lorsque la température chute sous les 1,500 K (type T). Les naines brunes près de la transition L/T devraient donc être partiellement recouvertes de nuages. De par leur rotation relativement rapide (2 h - 12 h), le couvert nuageux inhomogène des naines brunes devrait produire une variabilité photométrique observable en bande J (1.2 um), la longueur d’onde à laquelle les nuages ont la plus forte opacité. Ce mémoire présente les résultats d’une recherche de variabilité photométrique infrarouge pour une dizaine de naines brunes de type spectral près de la transition L/T. Les observations, obtenues à l’Observatoire du Mont-Mégantic, ont permis le suivi photométrique en bande J de neuf cibles. Une seule d’entre elles, SDSS J105213.51+442255.7 (T0.5), montre des variations périodiques sur une période d’environ 3 heures avec une amplitude pic-à-pic variant entre 40 et 80 mmag. Pour les huit autres cibles, on peut imposer des limites (3 sigma) de variabilité périodique à moins de 15 mmag pour des périodes entre 1 et 6 heures. Ces résultats supportent l’hypothèse qu’un couvert nuageux partiel existe pour des naines brunes près de la transition L/T mais ce phénomène demeure relativement peu fréquent. / Brown dwarfs are astronomical objects of low mass ( 0.012 - 0.075 M_Sun ) and low temperature ( T < 3,500 K ). While they do form like stars through gravitational collapse of a molecular gas cloud, they do not have sufficient mass to sustain nuclear fusion reactions in their core. Relatively hot brown dwarfs (type L) are covered by an homogeneous dust cloud cover that progressively disappears from their atmosphere when the temperature falls below 1,500 K (type T). Therefore, brown dwarfs near the L/T transition should be partially covered with clouds. Due to the fast rotation of brown dwarfs (2 h - 12 h), this inhomogeneous cloud cover should produce photometric variability observable in the J band (1.2 um), the wavelength at which the clouds have the strongest opacity. This thesis presents the results of a search for infrared photometric variability in brown dwarfs near the L/T transition. The observations, obtained at the Observatoire du Mont-Mégantic, have allowed the photometric follow-up of nine targets in the J band. Only one of them, SDSS J105213.51+442255.7 (T0.5), showed periodic variations with a period of about 3 hours with a peak-to-peak amplitude ranging from 40 to 80 mmag. For the remaining eight targets, we can place upper limits (3 sigma) of 15 mmag for the amplitude of periodic variability over a period range betwen 1 and 6 hours. While these results support the hypothesis that partial dust cloud covers do exist among L/T dwarfs, this phenomenon is by no means ubiquitous.

The United States Navy's involvement in the Vietnam War, especially its role in the region's inland waterways, has long been an overshadowed aspect of the conflict. Most histories ignore or minimize the Navy's contribution, especially its river patrol or 'brown water' role. Through archival and library research as well as interviews with U.S Navy Vietnam War veterans this thesis demonstrates the vital role played by the brown water navy in the northern provinces of South Vietnam. A key but understudied component of this effort was Task Force Clearwater, an improvised brown water fleet that-along with the maritime logistics campaign that it supported-would prove essential for the successful defense of South Vietnam's northernmost provinces and demonstrate the vital importance of inland naval power. Task Force Clearwater and its supported maritime logistics effort form a little explored component of the U.S. Navy's role in South Vietnam. A brown water task force that proved essential for the successful defense of the northern provinces of I Corps, Clearwater repeatedly demonstrated the vital importance of inland naval power and the critical need for reliable and protected routes of supply. The task force revealed many lessons that had been long understood, forgotten, and then relearned by the U.S. Navy, among them that control of inland waterways was perhaps the most advantageous form of logistical supply in war. Created in part to satisfy the ancient maxim of "keeping the supply lines open", the task force's role broadened with time. In the course of its existence the men and boats of Clearwater would provide not only the tools of war in I Corps but also provide key lessons for the future.

This study quantifies discolouration on the surface of Pinus radiata boards during kiln drying, particularly kiln brown stain (KBS), and models it as a function of chemical compounds present in the wood closest to the surface. The discolouration was investigated with two experimental factors: drying time, which consisted in drying at 70/120 ℃ for 0, 8, 16 and 24 hours; and leaching, done at three levels, noleaching, mild and severe, to reduce the soluble compounds present in wood suspected of developing coloured compounds. The colour change was quantified using a reflectance photometer (colour system CIE Yxy, brightness) and by the analysis of digital photographs (colour system CIE Lab). The chemical analysis of the wood closest to the surface of the boards determined fructose, glucose, sucrose (HPLC), total sugar (sum of fructose, glucose and sucrose), total nitrogen (combustion gas analysis), and phenols discriminated by molecular weight (Folin-Ciocalteu method). In the cause-effect analysis, colour was the dependent variable, and drying time and the determinations of chemical compounds were independent variables. After statistical analysis (ANOVA and MANOVA) the dependent variables to be included in the models were luminance factor (Y), brightness (R457 and the blue-to-yellow scale of CIE Lab (b); and the independent variables were drying time, nitrogen, total sugar, and high-molecular-weight phenols. Linear (multivariate regression) and non-linear models (Neural Networks) showed that discolouration during kiln drying was best predicted when the luminance factor (Y) was used to quantify colour change as a function of the content of nitrogen-containing compounds and drying time. Furthermore, the data were fitted into an empirical model based on simple reaction kinetics that considered the rate of discolouration as a function of nitrogen concentration. The results suggest that nitrogen could act as a limiting reactant in Maillard-type reactions that produce colour during kiln drying.

Closely jointed greywacke rock masses are widespread throughout both the North and South Islands of New Zealand and much of New Zealand's infrastructure is constructed upon greywacke rock masses. This thesis deals with determining the rock mass strength of unweathered closely jointed New Zealand greywacke rock masses. Currently, the estimation of rock mass strength and deformability is reasonably well predicted through the use of such empirical failure criteria as the Hoek-Brown failure criterion and empirical expressions to predict deformability. However, previous studies upon predicting the strength and deformability of unweathered closely jointed New Zealand greywacke rock masses has shown that existing empirical methods of determining strength and deformability are unsatisfactory. The problem with predicting rock mass strength and deformability moduli of New Zealand greywacke and the lack of adequate data to calibrate a failure criterion was the starting point for this work. The objective of this thesis was to increase the knowledge of intact and defect properties of closely jointed greywacke, develop reliable rock mass data with which to calibrate a failure criterion and improve the ability to estimate the rock mass strength of greywacke rock masses. A review of existing failure criteria for rock masses was conducted and of these criteria, the Hoek-Brown rock mass failure criteria was selected to calibrate to both the intact rock and rock mass failure data, because of its broad acceptance in the rock mechanics community. A database of greywacke properties was developed based on previous studies upon unweathered greywacke around New Zealand and is attached to the thesis as an Appendix. The database included descriptions of greywacke defect properties and mechanical properties of the intact rock and joints. From this database, inputs could be justified for numerical modelling and later analyses of failure criteria. Records from the construction archives of the Benmore and Aviemore hydroelectric power projects in the South Island of New Zealand were reviewed to obtain information and results from a series of shear tests carried out on unweathered closely jointed greywacke in the 1960s. Data on rock mass strength at failure and rock mass deformability were extracted from these records to assess the predictability of the failure criterion and deformability expressions. Problems experienced during the shear tests at the Aviemore dam site created doubt as to the actual rock mass strengths achieved at failure. The behaviour of these tests was studied using the finite difference code FLAC. The work was aimed at investigating the potential for transfer of shear force between the two concrete blocks sheared in each test and the impact shear force transfer had upon the likely normal stresses beneath each block at failure. The numerical modelling results indicated that a combination of preferential failure occurring in one direction, and doubt in the actual normal load applied to the concrete blocks during testing lead to premature failure in the blocks sheared upstream. The blocks sheared in the opposite direction failed at normal stresses that are reflective of the strength of an unweathered greywacke rock mass, but these results could be explained by failure occurring along defects therefore not satisfying the assumptions of homogeneity typically required of a rock mass failure criterion. The Hoek-Brown failure criterion for intact rock was investigated by fitting it to the largest intact greywacke datasets. For a full set of test data (i.e. including tensile data), the Mostyn & Douglas (2000) variant of the Hoek-Brown failure criterion gave the best fit for a full set of rock mass data. A multiple regression method was developed which improved the fitted curve to intact data in the tensile region and gave the best estimate of tensile strength if no existing lab results for tensile strength were available. These results suggest that the Hoek-Brown failure criterion is significantly limited in its applicability to intact NZ greywacke rock. Hoek-Brown input parameters different to those suggested by Hoek et al (2002) are recommended for using the Hoek-Brown failure criterion for intact NZ greywacke. For closely jointed NZ greywacke rock masses, the results from the shear tests at Aviemore and Benmore were separated into different GSI classes and Hoek-Brown envelopes fitted to the datasets by multiple regression. Revised expressions were proposed for each Hoek-Brown input parameter (mb, s, ab) as a function of the GSI. The resulting revised Hoek-Brown failure envelopes for NZ greywacke offer a significant improvement on the existing criterion used to predict the strength of NZ greywacke intact rock and rock masses. The differences in the behaviour of the reaction blocks that failed before the test blocks and the reduction in rock strength due to sliding along defects from that predicted could be reasoned from recorded observations and the behaviour of the concrete blocks during the shear tests. This study has clearly illustrated the need for continued research in this area. This includes (1) a means of assessing the role of defects upon the shear strength of closely jointed greywacke rock mass into a failure criterion, (2) further modelling of the in-situ shear tests by a discrete element procedure to expressly determine the role of the defect on failure, (3) more testing on rock masses to obtain more data to calibrate a rock mass failure criterion, and (4) more studies on predicting the strength of extremely disturbed rock masses.

Dans ce mémoire, nous présentons les études réalisées pour permettre l'observation de paires d'atomes corrélés produites lors de la collision de deux condensats de Bose-Einstein d'hélium métastable. Un système basé sur l'utilisation de trois faisceaux laser permet la réalisation d'un transfert Raman qui extrait d'un piège magnétique et sépare en deux parties d'impulsions moyennes opposées le condensat produit expérimentalement. Des processus de collisions élastiques, intervenant pendant la propagation des condensats, sont à l'origine de la diffusion de paires d'atomes dont les impulsions satisfont aux lois de conservation de l'énergie et de l'impulsion. La grande énergie interne des atomes d'hélium métastable rend possible l'utilisation d'un détecteur d'atome unique basé sur l'utilisation de galettes de microcanaux et sensible en position, donnant accès à une reconstruction tridimensionnelle des impulsions des atomes diffusés lors de la collision. L'étude de la statistique de ces impulsions permet la mise en évidence de corrélations entre les atomes diffusés, d'impulsions opposés. Le volume de corrélation mesuré peut être rapproché de l'extension de la distribution d'impulsion du condensat initial, elle même limitée par le principe d'incertitude de Heisenberg. Cette interprétation est confirmée par l'observation de corrélations entre les atomes diffusés dans une même direction. Un tel effet correspond à une manifestation de l'effet Hanbury Brown et Twiss pour des bosons indiscernables. La mise en place d'une telle source de paires d'atomes corrélés constitue un premier pas vers la réalisation d'expériences où l'intrication des paires produites pourra être confirmée.

Juday Creek, in St. Joseph County, Indiana, has been designated a salmonid stream due to its reproducing population of brown trout (Salmo trutta). Increasing development in the watershed in recent years has been accompanied by deterioration of the stream habitat. The purpose of this project is to analyze a proposed golf course project and develop a set of recommendations for best management practices (BMP's) which will mitigate the effects of the golf course on the trout habitat of Juday Creek.Site features were inventoried, and the design program was formulated to include aesthetics, playability, impact to fisheries and wildlife, and groundwater quality. Current stormwater best management practices were assessed for their applicability to this project. Additionally, cultural best management practices currently utilized in the golf course industry were reviewed. BMP recommendations include: 1. Use of temporary erosion control practices during construction to avoid sedimentation of the stream.2. Use of Integrated Pest Management including selection of low maintenance grass species.3. Use of vegetated swales to filter and divert golf course runoff to out-of-play areas for further filtering.4. Use of vegetated storm filter/infiltration/wetland retention areas as stormwater filters in out- of-play areas.5. Supplemental tree planting along the stream corridor to provide additional shading of the stream.6. Restoration of structure such as logs, boulders, and cobble in the stream to improve fish habitat. / Department of Landscape Architecture

De nos jours, les avatars et les réécritures du mythe du Graal puisent leur source d'inspiration dans la Littérature puisque la première mention littéraire de ce schème apparaît à la fin du XIIeme siècle dans Perceval ou le conte du Graal de Chrétien de Troyes. De par des origines ambivalentes (païennes et chrétiennes), le Graal s'est ancré dans l'imaginaire collectif comme un mythe rédempteur ou tout du moins, étant un idéal à atteindre. Si la quête médiévale chevaleresque demande une rigueur incomparable et une pureté d'âme et de corps pour mériter la révélation des mystères du Saint Calice aujourd'hui, les héros de la littérature populaire et de la culture de masse accèdent à ses secrets par le vecteur d'en-quêtes simplifiées. La dévaluation du mythe s'effectue à mesure des transferts qui s'opèrent dans différents genres, supports et médias mais également dans la réception que la société a du mythe du Graal. De Saint Graal à Graal, de Littérature à paralittérature, de la Bible à la télévision, ce travail cherche à mettre en évidence les différents aspects de ces transferts et tente de prouver qu'il existe des résonances et des points d'articulation entre ces domaines par l'interface du Graal. Dans ce sens, le motif sert aussi de porte-à-faux à une culture et à une littérature dites " mineures " qui peuvent toutefois, sous l'effet du Graal, devenir scientifiques et apporter de nouvelles pistes de réflexion sur le mythe, la société et la Littérature.

Ascetic Citizens: Religious Austerity and Political Crisis in Anglo-American Literature, 1681-1799, attends to a number of scenes of voluntary self-restraint in literary, political, and religious writings of the long eighteenth century, scenes that stage, what Alexis de Tocqueville calls, “daily small acts of self-denial” in the service of the nation. Existing studies of asceticism in Anglo-American culture during the period are extremely slim. Ascetic Citizens fills an important gap in the scholarship by re-framing religious practices of seclusion and self-denial as a broadly-defined set of civic practices that permeate the political, religious, and gender discourses of late seventeenth- and eighteenth-century Anglo-American culture. This thesis focuses on the transatlantic relevance of the ascetic citizen—a figure whose rhetorical utility derives from its capacity, as a marker of political and religious moderation, to deploy individual practices of religious austerity as a means of suturing extreme political binaries during times of political crisis. My conception of asceticism’s role in Anglo-American society is informed by an understanding of ascetic citizenship as a cluster of concepts and cultural practices linking the ascetic’s focus on bodily control to republican theories of political subjectivity. The notion that political membership presupposes a renunciation of personal liberties on the part of the individual citizen represents one of the key assumptions of ascetic citizenship. The future guarantee of individual political rights is ensured by present renunciations of self-interest. As such, the ascetic citizen functions according to the same economy by which the religious ascetic’s right to future eternal reward is ensured by present acts of pious self-abnegation. That is to say, republican political liberty is enabled by what we might call an ascetic prerequisite in which the voluntary self-sacrifice of civic rights guarantees the state’s protection of such rights from the infringements of one’s neighbour. While the abstemious nature of ascetic practice implies efficiency grounded in economic frugality, bodily self-restraint, and physical isolation, the ascetic citizen functions as the sanctioned perversion of a normative devotional practice that circumvents the division between profane self-interest and sacred disinterestedness. The relevance of ascetic citizenship to political culture is its political fluidity, its potential to exceed the ideological functions of the dominant culture while revealing the tension that exists between endorsement of, and dissent from, the civic norm. Counter-intuitively, the ascetic citizen’s practice is marked by a celebration of moderation, of the via media. Forging a space at the threshold between endorsement/dissent, the ascetic citizen maps the dialectic movement of cultural extremism, forging a rhetorically useful site of ascetic deferral characterized by the subject’s ascetic withdrawal from making critical decisions. Ascetic Citizens provides a detailed investigation of how eighteenth-century Anglo-American authors such as Daniel Defoe, Samuel Richardson, Hannah Webster Foster, and Charles Brockden Brown conceive of individual subjectivity as it exists in the pause or retired moment between competing political orders.

A computer program has been written to perform production optimization in submersible pump lifted wells.Production optimization was achieved by the principles of Nodal Analysis Technique which was applied between the reservoir and the wellhead ignoring the surface choke and separator.computer program has been written according to two lifting environment,which are:pumping with only liquid,pumping with both liquid and gas.