984 resultados para super-orbital re-entry
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LEcosse du XVIIIe siecle connait de grands changements qui seront a laune des transformations socio-economiques sous-tendant sa Revolution industrielle. Lhistoriographie sur le sujet est divisee entre deux visions du developpement nommees pour le bienfait de cette etude traditionnelle et revisionniste a savoir si ces transformations valident la notion dune revolution agraire . Cette etude propose une recension de ces deux courants et propose dappliquer leur analyse sur une region circonscrite, lAberdeenshire. A laide de lOld Statistical Account, source majeure pour letude de lhistoire moderne ecossaise, nous tenterons de demontrer que le caractere particulier du developpement des regions ne correspond pas a lapplication des conclusions nationales. Nous accorderons une attention speciale a la propriete fonciere, a limpact des enclosures et a la temporalite des changements. De par ses specificites, et son retard de modernisation agraire et agricole, nous croyons que la region suit le schema dresse par les historiens revisionnistes, c.-a-d. des changements structurels setendant sur un temps long et ne sinscrivant pas directement dans la periode 1755-1815, traditionnellement designee comme revolution agraire . Il sagirait plutot dune adaptation partielle et originale des nouvelles idees mises de lavant par les protagonistes de la modernisation.
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Cette thse lve en partie le voile sur lhistoire des sports fminins au Qubec de 1919 1961, soit de lge dor des sports fminins au Canada jusqu ladoption de la Loi sur la condition physique et le sport amateur par le gouvernement fdral. Elle montre comment les rapports de genre ont t re/produits dans les sports fminins en tudiant les discours et les pratiques, tout en portant une attention particulire linfluence quexercent lappartenance de classe, lethnicit et la religion sur les sports fminins. Lanalyse se penche dabord sur les discours des mdecins, des professeurs dducation physique et des clercs de lglise catholique pour tudier les prescriptions quils ont formules lgard de la participation sportive des femmes. Les ides de deux Montralaises, Myrtle Cook et Ccile Grenier, sont ensuite examines pour montrer comment elles contestent les discours dominants. Enfin, les pratiques sportives des femmes dans deux centres sportifs montralais, soit la Palestre nationale et le Young Womens Christian Association, ont t tudies de manire dtaille afin de mettre en lumire les diffrences, mais aussi certaines similitudes, entre lorganisation des sports fminins dans les communauts francophones et anglophones de la ville. Cette thse met en vidence les tensions qui dcoulent des rapports de genre, de classe, dethnicit et de lappartenance religieuse, et qui sont prsentes la fois dans les discours et les pratiques. Comme ailleurs en Amrique du Nord et mme ailleurs en Occident, les discours dominants au Qubec ne sont pas univoques, alors que des vues divergentes les contestent et que les pratiques sont plurielles. Tout en sinscrivant dans le mouvement plus large daccs des femmes aux sports en Occident, les discours et les pratiques observables Montral sen distinguent, notamment par la forte influence de lglise catholique et par les tensions ethniques. Le Qubec est donc un cas despce tout indiqu pour mettre en lumire la complexit de la re/production des rapports de genre travers lanalyse des sports fminins, ltude de ce champ constituant en mme temps une avenue de recherche fort stimulante pour mieux saisir lentre de la province dans la modernit.
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La polyvalence de la raction de couplage-crois C-N a t explore pour la synthse de deux nouvelles classes de ligands: (i) des ligands bidentates neutres de type N^N et (ii) des ligands tridentates neutres de type N^N^N. Ces classes de ligands contiennent des N-htrocycles aromatiques saturs qui sont coupls avec hexahydropyrimidopyrimidine (hpp). Les ligands forment de cycles six chanons sur la coordination du centre Ru(II). Ce fait est avantageux pour amliorer les proprits photophysiques des complexes de polypyridyl de Ru(II). Les complexes de Ru(II) avec des ligands bidents ont des missions qui dpendent de la basicit relative des N-htrocycles. Bien que ces complexes sont lectrochimiquement et photophysiquement attrayant, le problme de la stereopurit ne peut tre vit. Une conception soigneuse du type de ligand nous permet de synthtiser un ligand bis-bidentate qui est utile pour surmonter le problme de stereopurit. En raison de la spcialit du ligand bis-bidentate, son complexe diruthnium(II,II) prsente une grande diastroslectivit sans sparation chirale. Alors que l'unit de hpp agit comme un nuclophile dans le mcanisme de C-N raction de couplage crois, il peut galement agir en tant que groupe partant, lorsqu'il est activ avec un complexe de monoruthenium. Les complexes achiraux de Ru(II) avec les ligands tridents prsentent des meilleures proprits photophysiques en comparason avec les prototypes [Ru(tpy)2]2+ (tpy = 2,2: 6, 2-terpyridine). Lintroduction de deux units de hpp dans les ligands tridentates rend le complexe de Ru(II) en tant que absorbeur noir et comme NIR metteur (NIR = de langlais, Near Infra-Red). Cet effet est une consquence d'une meilleure gomtrie de coordination octadrique autour de l'ion Ru(II) et de la forte donation sigma des units hpp. Les complexes du Re(I) avec des ligands tridentates prsentent un comportement redox intressant et ils mettent dans le bleu. L'oxydation quasi-rversible du mtal est contrle par la donation sigma des fragments hpp, tandis que la rduction du ligand est rgie par la nature lectronique du motif N-htrocycle central du ligand lui-mme. Cette thse presente galement l'auto-assemblage des mtal-chromophores comme mtallo-ligands pour former des espces supramolculaires discretes utilisant des complexes neutres. Les synthses et proprits des mtaux-chromophores prcits et les supramolcules sont discutes.
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Des lois sont adoptees, des politiques implantees, des centaines de milliers de dollars investis dans la formation des employes, et puis ? Cette recherche de type exploratoire tente de jeter la lumiere sur ce qui se passe actuellement dans les points d'entree canadiens situes au Quebec en matiere de lutte contre la traite de personnes migrantes et de presenter, s'il y a lieu, les incoherences entre l'engagement du Canada a lutter contre la traite de personnes et les pratiques des agents des services frontaliers du Canada sur le terrain. Pour ce faire, nous avons interviewe sept agents des services frontaliers du Canada travaillant a l'Aeroport international Pierre-Elliott-Trudeau de Montreal, quatrieme poste frontalier aeroportuaire en importance au Canada et premier au Quebec, afin d'en apprendre davantage sur les connaissances ainsi que sur les experiences de ceux-ci en matiere de traite de personnes migrantes. Nous avons aussi rencontre quatre intervenants venant en aide aux victimes migrantes de la traite de personnes au Quebec, principalement dans la region de Montreal, dans le but d'en savoir un peu plus sur l'experience des victimes en lien avec l'Agence des services frontaliers du Canada et les impacts de ces experiences sur celles-ci. Si les agents interviewes semblent avoir une assez bonne idee, meme si celle-ci parait largement influencee par les medias, de ce qu'est la traite de personnes migrantes, rares sont ceux qui, dans le cadre de leurs fonctions, ont une experience pratique aupres des victimes. L'absence de formation substantielle et continue, la perception du role de l'ASFC par ses agents ainsi que le manque de leadership de la direction en ce qui a trait a la traite de personnes migrantes semblent etre des accrocs majeurs a la volonte politique du gouvernement canadien, plus particulierement de l'Agence des services frontaliers du Canada, de combattre la traite de personnes migrantes sur son propre territoire. Les obstacles sont nombreux dans la lutte contre la traite de personnes aux frontieres canadiennes et representent un defi de taille a la fois complexe et complique. Une approche centree sur la prevention et une plus grande sensibilisation des agents des services frontaliers du Canada proposent un debut de solution.
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Objectif : Cette thse a pour but de prciser les mcanismes neuropsychologiques de la douleur, de la rgulation endogne de la douleur et de l'hypoalgsie induite psychologiquement (HIP) par la synthse de prs de trente ans de recherche imagerie crbrale fonctionnelle. Mthodologie : tant donn l'abondance des tudes sur le sujet et le manque d'intgration de leurs rsultats, la technique de mtaanalyse quantitative base sur les coordonnes d'activation crbrale fut privilgie dans cette thse, telle quimplmente dans l'algorithme ALE (Activation Likelyhood Estimate). Une force supplmentaire de cette thse repose sur la rigueur du processus de slection des articles. En effet, les tudes incluses dans les mtaanalyses devaient satisfaire des critres stricts d'inclusion, ceci dans le but de favoriser la prcision et la validit des conclusions subsquentes. tude 1 : Le premier article visait identifier les aires crbrales impliques dans la rduction de la douleur par des mthodes psychologiques d'interventions. Les articles retenus portent sur une varit de mthodes d'intervention, telles que le placebo, l'hypnose, la mditation, la perception de contrle sur la stimulation douloureuse et l'induction d'motions. Les rsultats indiquent que l'HIP implique un vaste rseau d'activation qui comprend le cortex cingulaire antrieur, l'insula antrieure, les zones orbitofrontale et prfrontale latrale, ainsi que les rgions paritale, temporale et souscorticales. Ces activations reflteraient l'implication des mcanismes neuropsychologiques cognitifs et motionnels sous-tendent les interventions psychologiques cibles par ces tudes, incluant la conscience de soi et la motivation. De plus, les divergences de patron d'activation entre les approches ont t explores, notamment pour le placebo et la distraction. tude 2 : Le deuxime article a identifi des patrons d'activations prfrentiellement associs la perception de la douleur, l'HIP, ainsi que des activations communment associes la douleur et l'HIP. Les rsultats indiquent que 1) la perception de la douleur est associe l'activation d'aires somatosensorielles et motrices, ce qui pourrait tre le reflet de la prparation d'une action adaptative, 2) l'HIP est lie l'engagement de rgions prfrontales antromdianes et orbitales, possiblement en lien avec des processus motivationnels et motionnels, et 3) la douleur et l'HIP sont associs l'activation d'aires prfrontales dorsolatrales, de l'insula antrieure et du cortex cingulaire moyen, ce qui pourrait reflter l'engagement spontan pendant la douleur de mcanismes endognes de rgulation descendante. Conclusion : Par ces tudes, cette thse fait le point sur les mcanismes crbraux impliqus diffrentiellement dans la perception de la douleur, dans sa rgulation endogne et dans l'hypoalgsie induite psychologiquement.
The Inertio-Elastic Planar Entry Flow of Low-Viscosity Elastic Fluids in Micro-fabricated Geometries
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The non-Newtonian flow of dilute aqueous polyethylene oxide (PEO) solutions through microfabricated planar abrupt contraction-expansions is investigated. The contraction geometries are fabricated from a high-resolution chrome mask and cross-linked PDMS gels using the tools of soft-lithography. The small length scales and high deformation rates in the contraction throat lead to significant extensional flow effects even with dilute polymer solutions having time constants on the order of milliseconds. The dimensionless extra pressure drop across the contraction increases by more than 200% and is accompanied by significant upstream vortex growth. Streak photography and videomicroscopy using epifluorescent particles shows that the flow ultimately becomes unstable and three-dimensional. The moderate Reynolds numbers (0.03 Re 44) associated with these high Deborah number (0 De 600) microfluidic flows results in the exploration of new regions of the Re-De parameter space in which the effects of both elasticity and inertia can be observed. Understanding such interactions will be increasingly important in microfluidic applications involving complex fluids and can best be interpreted in terms of the elasticity number, El = De/Re, which is independent of the flow kinematics and depends only on the fluid rheology and the characteristic size of the device.
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Two Multifunctional photoactive complexes [Re(Cl)(CO)(3)-(MeDpe(+))(2)](2+) and [Re(MeDpe(+))(CO)(3)(bpy)](2+) (MeDpe(+) = N-methyl-4-[trans-2-(4-pyridyl)ethenyl]pyridinium, bpy = 2,2'-bipyridine) were synthesized. characterized. and their redox and photonic properties were investigated by cyclic voltammetry: ultraviolet-visible-infrared (UV/Vis/IR) spectroelectrochemistry, stationary UV/Vis and resonance Raman spectroscopy; photolysis; picosecond time-resolved absorption spectroscopy in the visible and infrared regions: and time-resolved resonance Raman spectroscopy. The first reduction step of either complex Occurs at about -1.1 V versus Fc/Fc(+) and is localized at MeDpe(+). Reduction alone does not induce a trans -> cis isomerization of MeDpe(+). [Re(Cl)(CO)(3)(MeDPe(+))(2)](2+) is photostable, while [Re(MeDpe(+))(CO)(3)(bpy)](2+) and free MeDpe(+) isomerize under near-UV irradiation. The lowest excited state of [Re(Cl)(CO)(3)(MeDPe(+))(2)](2+) has been identified as the Re(Cl)(CO)(3) -> MeDpe(+) (MLCT)-M-3 (MLCT = metal-to-ligand charge transfer), decaying directly to the ground state with lifetimes of approximate to 42 (73%) and approximate to 430ps (27%). Optical excitation of [Re(MeDpe(+))(CO)(3)(bpy)](2+) leads to population of Re(CO)(3) -> MeDpe(+) and Re(CO)(3) -> bpy (MLCT)-M-3 states, from which a MeDpe(+) localized intraligand 3 pi pi* excited state ((IL)-I-3) is populated with lifetimes of approximate to 0.6 and approximate to 10 ps, respectively. The 3IL state undergoes a approximate to 21 ps internal rotation, which eventually produces the cis isomer on a much longer timescale. The different excited-state behavior of the two complexes and the absence of thermodynamically favorable interligand electron transfer in excited [Re(MeDpe(+))(CO)(3)(bpy)](2+) reflect the fine energetic balance between excited states of different orbital origin, which can be tuned by subtle Structural variations. The complex [Re(MeDpe+)(CO)(3)(bpy)](2+) emerges as a prototypical, multifunctional species with complementary redox and photonic behavior.
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Background: Prolonged and exaggerated postprandial plasma triacylglycerol (TAG) concentrations are considered as an independent risk factor for coronary artery disease. Western populations eat many meals at regular intervals, and can be in a postprandial state for at least 17h of a 24h period. After consuming 2 meals an early plasma TAG peak has been observed after the second meal, the origin of which is unclear. Aim of the study: To test the hypothesis that the early TAG peak observed following sequential meals was of intestinal origin and represented fat derived from the previous meal. Methods: Postprandial plasma lipaemic responses of 17 healthy postmenopausal women were studied by giving a test breakfast followed by a lunch. Watermiscible retinyl palmitate (RP) was added to the breakfast, but not the lunch test meal. Plasma TAG, retinyl esters (RE) and apo B-48 were determined for a 10h period following breakfast. Results: In response to the test meals, RE, apo B-48 and TAG showed multiple peaks. Despite omission of RP from the lunch, RE showed an early peak response after ingestion of lunch in 15 of 17 subjects. The peak response after lunch of all three markers appeared significantly earlier compared with their respective peak responses after the breakfast (P < 0.0001). The area of RE response after lunch was significantly correlated with the RE lipaemic response to the breakfast (r = 0.67; P < 0.004) and to the fasting TAG concentration (r = 0.48; P < 0.05). Conclusions: Since the lunch did not contain RP, the distinctive second influx of RE after lunch was believed to have originated from the breakfast. This, together with the fact that all three markers showed an earlier response to the lunch than the breakfast, supports the view that ingestion of a second meal provokes entry of fat from the previous meal, from an as yet unidentified site (gut, enterocytes, lymph). The results indicate that the degree of TAG "storage" from previous meals might be a function of TAG tolerance and provide a possible site of regulation of the entry of fat into the systemic circulation.
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The lowest allowed electronic transition of fac-[Re(Cl)(CO)(3)(bopy)(2)] (bopy = 4-benzoylpyridine) has a Re --> bopy MLCT character, as revealed by UV-vis and stationary resonance Raman spectroscopy. Accordingly, the lowest-lying, long-lived, excited state is Re --> bopy (MLCT)-M-3. Electronic depopulation of the Re(CO)(3) unit and population of a bopy pi* orbital upon excitation are evident by the upward shift of v(Cequivalent toO) vibrations and a downward shift of the ketone v(C=O) vibration, respectively, seen in picosecond time-resolved IR spectra. Moreover, reduction of a single bopy ligand in the (MLCT)-M-3 excited state is indicated by time-resolved visible and resonance Raman (TR3) spectra that show features typical of bopy(.-). In contrast, the lowest allowed electronic transition and lowest-lying excited state of a new complex fac-[Re(bopy)(CO)(3)(bpy)](+) (bpy = 2,2'-bipyridine) have been identified as Re --> bpy MLCT with no involvement of the bopy ligand, despite the fact that the first reduction of this complex is bopy-localized, as was proven spectroelectrochemically. This is a rare case in which the localizations of the lowest MLCT excitation and the first reduction are different. (MLCT)-M-3 excited states of both fac-[Re(Cl)(CO)(3)(bopy)(2)] and fac-[Re(bopy)(CO)(3)(bpy)](+) are initially formed vibrationally hot. Their relaxation is manifested by picosecond dynamic shifts of v(Cequivalent toO) IR bands. The X-ray structure of fac-[Re(bopy)(CO)(3)(bpy)](PF6CH3CN)-C-. has been determined.
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This article contributes to the debate on livelihood diversification in rural sub-Saharan Africa, focusing specifically on the growing economic importance of artisanal and small-scale mining (ASM) in the region. The precipitous decline in the value of many export crops and the removal of subsidies on crucial inputs such as fertilizers have made smallholder production unviable, forcing many farmers to branch out into non-farm activities to supplement their incomes. One of the more popular destinations for poor farmers is the low-tech ASM sector which, because of its low barriers to entry, has absorbed millions of rural Africans over the past two decades, the majority of whom are engaged in the extraction of near-surface mineral deposits located on concessions that have been demarcated to multinational corporations. The efforts made hitherto to control this illegal mining activity, both through force and regulation, however, have had little effect, forcing many of the regions governments and private sector partners to re-think their approaches. One strategy that has gained considerable attention throughout the region is intensified support for agrarian-orientated activities, many of which, despite the problems plaguing smallholder agricultural sector and challenges with making it more economically sustainable, are being lauded as appropriate alternative sources of employment to artisanal mining. After examining where artisanal mining fits into the de-agrarianization puzzle in sub-Saharan Africa, the article critiques the efficacy of re-agrarianization as a strategy for addressing the regions illegal mining problem. A case study of Ghana is used to shed further light on these issues.
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Giant planets helped to shape the conditions we see in the Solar System today and they account for more than 99% of the mass of the Suns planetary system. They can be subdivided into the Ice Giants (Uranus and Neptune) and the Gas Giants (Jupiter and Saturn), which differ from each other in a number of fundamental ways. Uranus, in particular is the most challenging to our understanding of planetary formation and evolution, with its large obliquity, low self-luminosity, highly asymmetrical internal field, and puzzling internal structure. Uranus also has a rich planetary system consisting of a system of inner natural satellites and complex ring system, five major natural icy satellites, a system of irregular moons with varied dynamical histories, and a highly asymmetrical magnetosphere. Voyager 2 is the only spacecraft to have explored Uranus, with a flyby in 1986, and no mission is currently planned to this enigmatic system. However, a mission to the uranian system would open a new window on the origin and evolution of the Solar System and would provide crucial information on a wide variety of physicochemical processes in our Solar System. These have clear implications for understanding exoplanetary systems. In this paper we describe the science case for an orbital mission to Uranus with an atmospheric entry probe to sample the composition and atmospheric physics in Uranus atmosphere. The characteristics of such an orbiter and a strawman scientific payload are described and we discuss the technical challenges for such a mission. This paper is based on a white paper submitted to the European Space Agencys call for science themes for its large-class mission programme in 2013.
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The search for rocky exoplanets plays an important role in our quest for extra-terrestrial life. Here, we discuss the extreme physical properties possible for the first characterised rocky super-Earth, CoRoT-7b (R(pl) = 1.58 +/- 0.10 R(Earth), M(pl) = 6.9 +/- 1.2 M(Earth)). It is extremely close to its star (a = 0.0171 AU = 4.48 R(st)), with its spin and orbital rotation likely synchronised. The comparison of its location in the (M(pl), R(pl)) plane with the predictions of planetary models for different compositions points to an Earth-like composition, even if the error bars of the measured quantities and the partial degeneracy of the models prevent a definitive conclusion. The proximity to its star provides an additional constraint on the model. It implies a high extreme-UV flux and particle wind, and the corresponding efficient erosion of the planetary atmosphere especially for volatile species including water. Consequently, we make the working hypothesis that the planet is rocky with no volatiles in its atmosphere, and derive the physical properties that result. As a consequence, the atmosphere is made of rocky vapours with a very low pressure (P <= 1.5 Pa), no cloud can be sustained, and no thermalisation of the planet is expected. The dayside is very hot (2474 +/- 71 K at the sub-stellar point) while the nightside is very cold (50-75 K). The sub-stellar point is as hot as the tungsten filament of an incandescent bulb, resulting in the melting and distillation of silicate rocks and the formation of a lava ocean. These possible features of CoRoT-7b could be common to many small and hot planets, including the recently discovered Kepler-10b. They define a new class of objects that we propose to name ""Lava-ocean planets"". (C) 2011 Elsevier Inc. All rights reserved.
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Efforts to estimate the magnitude of the incumbency effect in U.S. House elections and assess its political meaning have been complicated by two omitted-variables problems. First, in the absence of an adequate measure of incumbent prospects, estimates of the magnitude of the incumbency effect fail to control for selection effects associated with the decision incumbents make about whether to run for reelection. Strategic incumbents enter races they think they can win and withdraw when they expect to lose. The consequence is an upward bias in estimates of incumbents electoral advantages. Second, the normative implications of high reelection rates cannot be assessed without measuring incumbent quality, since a possible explanation for their electoral success is that incumbents are of high quality and doing a good job. We propose a strategy for measuring incumbent prospects and quality, demonstrate the strategic nature of incumbent and challenger entry, re-estimate the incumbency effect, and show that incumbent quality has an impact on electoral outcomes. Our conclusion is that incumbents advantages in House elections have been over estimated while the positive basis of incumbent safety is typically under appreciated.
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The master thesis for the achievement of the academic status master of science in international management (MPGI) will aim to solve the research question of how institutional voids affect the entry decision-making process of foreign venture capital firms coming to Brazil. This is a timely matter since in the past years there has been a sudden eruption of foreign VC involvement in Brazil. Based on the actionable framework by Khanna and Palpeu (2010) we conducted quantitative as well as qualitative research with two sets of interview partners in a two-phase analysis. We interviewed experts from VC firms, foreign VC firms based in Brazil and perspective VC firms that are looking to come to Brazil. We started with the former, derived lessons learned and analyzed how they affect the latter in reaching a decision. As we expected we found that depending on the industry that ventures are in, institutional voids can either pose an opportunity or a threat and hence attract or push away potential VC firms entering Brazil. Opportunities exist especially when exploiting institutional voids, for example through ventures in the marketplace efficiency. Threats are posed by investments in for instance hard infrastructure, where the economic, political and judicial systems as well as corruption and bureaucracy play demanding roles.
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The objectives of this study were, through a literature review, to point the differences between orbital implants and their advantages and disadvantages, to evaluate prosthesis motility after orbital implants are inserted, and to point the implant wrapping current risks. Sixty-seven articles were reviewed. Enucleation implants can be autoplastics or alloplastics and porous (including natural and synthetic hydroxyapatite [HA]) or nonporous (silicone). Hydroxyapatite is the most related in the literature, but it has disadvantages, too, that is, all orbital implants must be wrapped. Exposure of the porous orbital implant can be repaired using different materials, which include homologous tissue, as well as autogenous graft, xenograft, and synthetic material mesh. The most used materials are HA and porous polyethylene orbital implant. The HA implant is expensive and possibly subject corals to damage, different from porous polyethylene orbital implants. Porous implants show the best prosthesis motility and a minimum rate of implants extrusion. Implant wraps can facilitate smoother entry of the implant into the orbit and allow reattachment of extraocular muscles. They also serve as a barrier between the overlying soft tissue and the rough surface of the implant, protecting implants from exposure or erosion.
