Pour mieux comprendre leurs propriétés, diverses nanostructures individuelles ont été étudiées à l’aide d’une technique couplant microscopie à force atomique et spectroscopie Raman confocale. Sous excitation lumineuse polarisée, la composition chimique, la structure et la présence de défauts a pu être précisée dans des nanobâtonnets d’oxydes métalliques (ZnO et α-Fe2O3). Sous irradiation laser résonnante, les spectres de nanotubes de carbone monoparoi enrobés de polymères ont révélé notamment l’absence de transfert de charge polymère-nanotube et un effet de désolvatation. Finalement, des feuillets de graphène oxydé et des ADNs double-brin peignés ont pu être préparés et caractérisés par spectroscopie Raman exaltée par effet de pointe en atteignant une résolution spatiale latérale voisine du rayon de courbure de l’apex de la pointe utilisée (12 nm), bien plus faible que la limite de diffraction, ce qui ouvre la voie à de nouveaux travaux spectroscopiques à l’échelle nanométrique. / To better understand their properties, various nanostructures have been studied using a technique combining atomic force microscopy and confocal Raman spectroscopy. Under polarized light excitation, the chemical composition, the structure and the presence of defects has been described in metal oxides nanorods (ZnO et α-Fe2O3). Under resonant laser excitation, Raman spectra of polymer-wrapped single-walled carbon nanotubes have revealed the absence of polymer-nanotube charge transfer and an effect due to desolvation. Finally, graphene oxide sheets and combed double-stranded DNAs have been prepared and characterized using tip-enhanced Raman spectroscopy with a lateral spatial resolution down to the curvature radius of the apex of the used tip (12 nm), well below the diffraction limit, which opens new opportunities for spectroscopic works at the nanometer scale.

Anandamide (NAE 20:4) or arachidonlyethanolamine (AEA) is the most widely studied N-acylethanolamine (NAE) because it mediates several physiological functions in mammals. In vascular plants, 12-18C NAEs inhibit growth in an abscisic acid (ABA)-dependent and -independent manner. Anandamide, which is unique to bryophyte Physcomitrella patens, inhibited gametophyte growth and reduced chlorophyll content when applied exogenously. It is hypothesized that anandamide mediates its responses through morphological and cellular changes. Following growth inhibition by short-term anandamide-treatment, microscopic analyses revealed relocated chloroplasts and depolymerized F-actin in protonemal tips. Long-term treatment showed partially bleached gametophyte cells with degraded and browning chloroplasts. These anandamide-mediated responses have physiological implications as AEA may function as a signal for gametophytes to activate secondary dormancy as seen with ABA. Future studies will investigate the role of AEA in mediating stress responses and possible interaction with ABA.

A incidência de diabete melito (DM) tem aumentado, principalmente em idosos. Evidências epidemiológicas mostram que obesidade e gordura abdominal constituem fator de risco para o desenvolvimento de DM. Objetivo: Verificar a associação da incidência de DM referida com obesidade e gordura abdominal, em coorte de idosos domiciliados no município de São Paulo/Brasil - 2000 e 2006. Casuística e métodos: Foram utilizados dados do Estudo SABE Saúde, Bem-estar e Envelhecimento, longitudinal, epidemiológico, de base domiciliar, realizado no município de São Paulo, em 2000 (2.143 idosos), e em 2006 (1.115 idosos). A população de estudo foi constituída por idosos ( 60 anos), de ambos os sexos, selecionados por amostra probabilística, e que não referiram DM, em 2000, e que apresentaram todos os dados necessários a este estudo. As variáveis analisadas foram: DM referida, com alternativa de resposta dicotômica (sim ou não), obesidade, pelo índice de massa corporal - IMC 30 kg/m², gordura abdominal (circunferência da cintura CC 88 cm, para mulheres, e 102 cm, para homens; e razão cintura/quadril RCQ 1, para homens, e 0,85, para mulheres) e características sociodemográficas (sexo, grupo etário, escolaridade, companhia no domicílio). Para verificar a associação entre as variáveis, utilizou-se teste Rao Scott, para amostra complexa, e regressão logística múltipla (p<0,05) e o programa Stata/SE 10.0 for Windows. Resultados: Dos 1.115 idosos, foram reavaliados 914, sendo que 72 constituíram os novos casos de Manuela F. de Almeida DM (7,7 por cento /1.000 pessoa/ano). Verificou-se que a maior proporção (58 por cento ) de indivíduos que referiram DM, era composta por mulheres. Ainda que a obesidade tenha se associado, positivamente, com referência de DM, constatou-se que a RCQ (OR=2,32; IC=1,47-3,67) e CC (OR= 2,33; IC=1,44-3,77) foram preditoras para DM referida. Conclusão: De todas as variáveis analisadas, apenas a gordura abdominal constituiu fator de risco para incidência da doença, no período de 6 anos / The incidence of diabetes mellitus (DM) has increased, mainly in aged persons. Epidemiological evidences show that obesity and abdominal fat constitute risk factor for development of DM. Objective: To verify the association the incidence of DM with obesity and abdominal fat, in cohort of elderly domiciled in São Paulo / Brazil - 2000 and 2006. Casuistic and methods: It were analized data of the SABE Survey, a longitudinal, epidemiologic and household based study, carried in the city of São Paulo, in 2000 (2,143 elderlies) and 2006 (1,115 elderlies). The study population was constituted by aged ( 60 years), of both gender, selected by probabilist sample, who did not reported DM, in 2000, with all necessary data to this study. The analized variables were: reported DM, with dicotomic answer (yes or no), obesity, by body mass index - BMI 30 kg/m², abdominal fat (waist circunference - WC 88 cm, for women, and 102 cm, for men; and waist-to-hip ratio WHR 1, for men, and 0.85, for women) and socio-demographics characterstics (gender, age group, educational status and home company). To verify the association among the variables, it was applied the Rao Scott test, for complex samples, multiple logistic regression (p<0.05) and statistical software Stata/SE 10.0 for Windows. Results: Out of the 1,115 elderlies, it were re-assessed 914, being 72 as new cases of DM (7.7 per cent /1,000 people/year). It was verified that a greater proportion (58 per cent ) of the subjects who reported DM, was Manuela F. de Almeida composed by females. Even though obesity was positively associated to reported DM, WHR (OR=2.33; IC=1.47-3.77) and WC (OR= 2.32; IC=1.44-3.67) were predictors for DM. Conclusion: Of all variables analized, only abdominal fat was considered risk factor for the incidence of this disease, in a period of 6 years

"An apparatus for the delivery of radiation to the tip-sample interface of an Atomic Force Microscope (AFM) is demonstrated. The Pulsed Light Delivery System (PLDS) was fabricated to probe photoinduced conformational changes of molecules using an AFM. The PLDS is 67 mm long, 59 mm wide, and 21 mm high, leaving clearance to mount the PLDS and a microscope slide coated with a thin film of photoactive molecules beneath the cantilever tip of a stand-alone AFM. The PLDS is coupled into a fiber pigtailed Nd:Yag frequency doubled laser, operating at a wavelength of 532 nm. The radiation delivered to a sample through the PLDS can be configured for continuous or pulsed mode. The maximum continuous wave (CW) power delivered was 0.903 mW and the minimum pulse width was 12.3 ms (maximal 401 ms), corresponding to a minimal energy of 0.150 nJ (maximal 362 nJ), and had a cycle duration of 10.0 ms. The PLDS consists of micro-optical components 3.0 mm and smaller in diameter. The optical design was inspired by the three-beam pick-up method used in CD players, which could provide a method to focus the pulse of light onto the sample layer. In addition, the system can be easily modified for different operational parameters (pulse width, wavelength, and power). As proof that the prototype design works, we observed a photoinduced ‘bimetallic’ bending of the cantilever, as evidenced by observing no photoinduced bending when a reflective-coated cantilever was replaced by an uncoated cantilever. Using the apparatus will allow investigation of many different types of molecules exhibiting photoinduced isomerization."

A thermal tip clearance control system provides a robust and flexible means of manipulating the closure between the casing and the rotating blade tips in a jet engine, reducing undesirable tip leakage flows. This may be achieved using an impingement cooling scheme on the external casing of the engine in conjunction with careful thermal management of internal over-tip seal segment cavity. For a reduction in thrust specific fuel consumption, the mass flow rate of air used for cooling must be minimised, be at as low a pressure as possible and delivered through a light weight structure surrounding the rotating components in the turbine. This thesis first characterises the effectiveness of a range of external impingement cooling arrangements in typical engine casing closure system. The effects of jet-to-jet pitch, number of jets, inline and staggered alignment of jets, arrays of jets on flange, on an engine representative casing geometry are assessed through comparison of the convective heat transfer coefficient distributions in a series of numerical studies. A baseline case is validated experimentally. The validation data allowed the suitability of different turbulence closure models to be assessed using a commercial RANS solver. Importantly for each configuration the thermal contraction of an idealised engine casing is predicted using thermo-mechanical finite element models, at a series of operating conditions representing engine idle to maximum take-off conditions. Cooling is provided by manifolds attached to the outside of the engine. The assembly tolerance of these components leads to variation in the standoff distance between the manifold and the casing. For cooling arrangements with promising performance, the study is extended to characterise the variation in closure with standoff distance. It is shown that where a sparse array of non-interacting jets is used the system can be made tolerant of large build misalignments. The casing geometry itself contributes to the thermal response of the system, and, in an additional study, the effect of casing thickness and circumferential thermal control flanges are investigated. Restriction of the passage of heat into the flanges was seen to be dramatically change their effectiveness and slight necking of the flanges at their root was shown to improve the performance disproportionally. High temperature secondary air flowing past the internal face of the engine casing tends to heat the casing, causing it to grow. Experimental and numerical characterisation of a heat transfer within a typical over-tip segment cavity heat transfer is presented in this thesis for the first time. A simplified modelling strategy is proposed for casing and a means to reduce the casing heat pickup by up to 25 % was identified. The overall validity of the modelling approach used is difficult to validate in the engine environment, however limited data from a test engine temperature survey became available during the course of the research. By modelling this engine tip clearance control system it was shown that good agreement to the temperature distribution in the engine casing could be achieved where full surface external heat transfer coefficient boundary conditions were available.

L’objectif du présent travail est d’une part d’évaluer les performances d’accès au mot chez des adultes jeunes (M = 22.1 ans) et âgés (M = 68.7 ans) et, d’autre part, de préciser la fonctionnalité des processus d’activation et d’inhibition lexicales avec l’âge. Dans le domaine du traitement des mots écrits, six études sont conduites en contrôlant le niveau de vocabulaire des participants. En utilisant des indices lexicaux objectifs et subjectifs adaptés aux adultes jeunes et âgés (Expérience 1a), nous observons une diminution des effets de fréquence objective (Expériences 1b-2) et de fréquence du voisinage orthographique avec l’âge (Expérience 4) dans la tâche de décision lexicale. D’autres données, obtenues avec cette tâche, précisent que la modification de l’effet de fréquence du voisinage avec l’âge est sensible à la familiarité des mots (Expériences 5-6), recueillie auprès d’adultes jeunes et âgés (Expérience 3). Dans le domaine de la production langagière orale, deux études utilisant un paradigme d’induction de Mot sur le Bout de la Langue (MBL) sont menées. Les résultats montrent que le nombre de MBL augmente avec l’âge (Expérience 7), indépendamment du niveau de vocabulaire. De plus, traiter un mot lié en son à la cible facilite autant sa récupération chez les adultes jeunes et âgés, tandis que traiter un mot lié en sens à la cible gêne sa récupération, et ce d’autant plus que les adultes sont âgés (Expérience 8). Dans l’ensemble, l’hypothèse combinée d’un déficit d’activation et d’inhibition, mise en lien avec les caractéristiques langagières des populations, permet de rendre compte de la modification des performances lexicales avec l’âge. / The aim of this study is to evaluate word access performances of young (M = 22.1 years) and older (M = 68.7 years) adults, and to specify possible changes in lexical activation and inhibition processes with aging. In the field of written word processing, six studies were conducted in which the participant vocabulary level was controlled. When using objective and subjective lexical measures appropriated to young and older adults (Experiment 1a), an age-related decreased was found for the objective frequency effect (Experiments 1b-2) and for the orthographic neighborhood frequency effect (Experiment 4) in the lexical decision task. Other data from this task indicated that the age-related change in the neighborhood frequency effect was sensitive to word familiarity ratings (Experiments 5-6) collected from young and older adults (Experiment 3). In field of the oral language production, two studies were run with a paradigm for inducing tip of the tongue (TOT) states. The results indicated that the number of TOT increased with aging (Experiment 7), which was not due to the vocabulary level. In addition, processing a word phonologically related to the target facilitated its recovery in young and older adults while processing a word semantically related to the target hindered its recovery, more for the older that for the young adults (Experiment 8). Overall, the combined hypothesis of activation and inhibition deficits, associated with linguistic characteristics of populations, can account for lexical performance changes with aging.

Au Niger, les bonnes performances macroéconomiques enregistrées, consécutivement à la mise en œuvre du document stratégique de réduction de la pauvreté, suscitent la question de leur impact par rapport à l'évolution de l'inégalité et de la pauvreté. La présente recherche se propose d'analyser les spécificités des dynamiques d'inégalité et de pauvreté inhérentes au nouveau processus de développement, à partir de données d'enquêtes auprès des ménages entre 2005 et 2007/2008. Dans un premier temps, l'analyse, en statique comparative, indique une légère baisse des privations monétaires au Niger. Toutefois, des disparités semblent prévaloir entre les zones rurales et urbaines du pays. Globalement, la distribution des dépenses n'est pas inégalitaire, et le processus de croissance économique se révèle pro-pauvres au Niger, sauf dans la capitale où la croissance semble être pro-riches. Dans un second temps, la prise en compte de l'hétérogénéité de la pauvreté à travers la distinction entre la pauvreté chronique et transitoire, en relation avec la vulnérabilité, précise davantage l'appréhension des privations. D'une part, si la pauvreté chronique a sensiblement baissé, on note une progression de la pauvreté transitoire. D'autre part, l'étude souligne la forte vulnérabilité des ménages nigériens, notamment les ménages non pauvres qui ont une probabilité élevée d'exposition au risque de pauvreté à court terme. Finalement, l'analyse des privations au Niger est approfondie en intégrant une approche non monétaire. Les résultats obtenus confirment la complémentarité des approches mesurant les privations dans le cas du Niger.

The objective of this thesis is to study the fracture behavior of bulk metallic glasses. For this purpose, detailed finite element investigation of the mode I and mixed mode (I and II) stationary crack tip fields under plane strain, small scale yielding conditions is carried out. An implicit backward Euler finite element implementation of the Anand and Su constitutive model [Anand, L. and Su, C., 2005, J. Mech. Phys. Solids 53, 1362] is used in the simulations. The effects of internal friction (μ), strain softening, Poisson's ratio (ν) and elastic mode mixity (Me) on the near-tip stress and deformation fields are examined. The results show that under mode I loading, a higher μ leads to a larger normalized plastic zone size and higher plastic strain level near the notch tip, but causes a substantial decrease in the opening stress. The brittle crack trajectories and shear band patterns around the notch are also simulated. An increase in ν reduces the extent of plastic zone and plastic strain levels in front of the notch tip. The results from mixed mode simulations show that increase in the mode II component of loading dramatically increases the maximum plastic zone extent, lowers the stresses and significantly enhances the plastic strain levels near the notch tip. Higher μ causes the peak magnitudes of tensile tangential stress to decrease. The implications of the above results on the fracture response of bulk metallic glasses are discussed. The possible variations of fracture toughness with mode mixity predicted by employing two simple fracture criteria are examined. Finally, mixed mode (I and II) fracture experiments on a Zr-based bulk metallic glass are performed. It is found that the fracture toughness increases with Me and Jc under mode I is higher than that under mode II loading by a factor of 4. The operative failure mechanism and fracture process zone size are discerned based on observations of incipient crack growth and fractographs. Lastly, a fracture criterion is proposed which predicts the experimentally observed variation of fracture toughness with mode mixity.

No description available.

To stay competitive internationally, the Swedish forestry sector must increase its productivity by 2 to 3% annually. There are a variety of ways in which productivity can be increased. One option is to develop remote-controlled or unmanned machines, thus reducing the need for operator intervention. Another option—and one that could be achieved sooner than full automation—would be to make some functions semi-automatic. Semi-automatic operation of the knuckle boom and felling head in particular would create “mini-breaks” for the operators, thereby reducing mental and physiological stress. It would also reduce training time and increase the productivity of a large proportion of operators. The objective of this thesis work has been to develop and evaluate algorithms for simplified boom control on forest machines. Algorithms for so called boom tip control, as well as automatic boom functions have been introduced. The algorithms solve the inverse kinematics of kinematically redundant knuckle booms while maximizing lifting capacity. The boom tip control was evaluated – first by means of a kinematic simulation and then in a dynamic forest machine simulator. The results show that boom tip control is an easier system to learn in comparison to conventional control, leading to savings in production due to shorter learning times and operators being able to reach full production sooner. Boom tip control also creates less mental strain than conventional control, which in the long run will reduce mental stress on operators of forest machines. The maximum lifting capacity algorithm was then developed further to enable TCP path-tracking, which was also implemented and evaluated in the simulator. An evaluation of the fidelity of the dynamic forest machine simulator was performed to ensure validity of the results achieved with the simplified boom control. The results from the study show that there is good fidelity between the forest machine simulator and a real forest machine, and that the results from simulations are reliable. It is also concluded that the simulator was a useful research tool for the studies performed in the context of this thesis work. The thesis had two overall objectives. The first was to provide the industry and forestry sector with usable and verified ideas and results in the area of automation. This has been accomplished with the implementation of a simplified boom control and semi-automation on a forwarder in a recently started joint venture between a hydraulic manufacturer, a forest machine manufacturer and a forest enterprise. The second objective was to strengthen the research and development links between the forestry sector and technical university research. This has been accomplished through the thesis work itself and by a number of courses, projects and Masters theses over the last three years. About 150 students in total have been studying forest machine technology in one way or the other. / QC 20100729