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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Human haptic perception is interrupted by explorative stops of milliseconds

Grunwald, Martin, Muniyandi, Manivannan, Kim, Hyun, Kim, Jung, Krause, Frank, Müller, Stephanie, Srinivasan, Mandayam A. January 2014 (has links)
The explorative scanning movements of the hands have been compared to those of the eyes. The visual process is known to be composed of alternating phases of saccadic eye movements and fixation pauses. Descriptive results suggest that during the haptic exploration of objects short movement pauses occur as well.The goal of the present study was to detect these \"explorative stops\"(ES) during one-handed and two-handed haptic explorations of various objects and patterns, and to measure their duration. Additionally, the associations between the following variables were analyzed:(a) between mean exploration time and duration of ES, (b) between certain stimulus features and ES frequency, and (c) the duration of ES during the course of exploration.:Introduction; Materials and methods; Results; Discussion
22

Continuous flash extraction of alcohols from fermentation broth

Teye, Frederick David 30 March 2009 (has links)
A new method of in situ extraction of alcohols from fermentation broth was investigated. The extraction method exploited the latent advantages of the non-equilibrium phase interaction of the fluid system in the flash tank to effectively recover the alcohol. Carbon dioxide gas ranging from 4.2L/min to 12.6L/min was used to continuously strip 2 and 12% (v/v) ethanol solution in a fermentor with a recycle. Ethanol and water in the stripped gas was recovered by compressing and then flashing into a flash tank that was maintained at 5 to 70bar and 5 to 55oC where two immiscible phases comprising CO2-rich phase (top layer) and H2O-rich phase (bottom layer) were formed. The H2O-rich bottom layer was collected as the Bottoms. The CO2-rich phase was continuously throttled producing a condensate (Tops) as a result of the Joule-Thompson cooling effect. The total ethanol recovered from the extraction scheme was 46.0 to 80% for the fermentor containing 2% (v/v) ethanol and 57 to 89% for the fermentor containing 12% (v/v) ethanol. The concentration of ethanol in the Bottoms ranged from 8.0 to 14.9 %(v/v) for the extraction from the 2 %(v/v) ethanol solution and 40.0 to 53.8 %(v/v) for the 12% (v/v) fermentor ethanol extraction. The Bottoms concentration showed a fourfold increase compared to the feed. The ethanol concentration of the Tops were much higher with the highest at approx. 90% (v/v) ethanol, however the yields were extremely low. Compression work required ranged from 6.4 to 20.1 MJ/kg ethanol recovered from the gas stream in the case of 12% (v/v) ethanol in fermentor. The energy requirement for the 2% (v/v) extraction was 84MJ/kg recovered ethanol. The measured Joule-Thompson cooling effect for the extraction scheme was in the range of 10 to 20% the work of compressing the gas. The lowest measured throttle valve temperature was -47oC at the flash tank conditions of 70bar and 25oC. Optimization of the extraction scheme showed that increasing the temperature of the flash tank reduced the amount of ethanol recovered. Increasing the pressure of the flash tank increased the total ethanol recovered but beyond 45bar it appeared to reduce the yield. The 12.6L/min carbon dioxide flow rate favored the high pressure(70bar) extraction whiles 4.2L/min appeared to favor the low pressure(40bar) extraction. The studies showed that the extraction method could potentially be used to recover ethanol and other fermentation products. / Master of Science
23

Challenges encountered by women who requested termination of pregnancy services in the North West Province of South Africa

Mokgethi, Nomathemba Emily Blaai 08 1900 (has links)
In 1996 the South African government legalised the termination of pregnancy (TOP) services, allowing women to choose to terminate unplanned pregnancies at designated facilities. Although TOP services are available, pregnant women continue to use illegal abortion services, with potentially life-risking consequences. The purpose of this study was to identify challenges encountered by women requesting TOP services, and to make recommendations for improved policies and practices, enabling more women in the North West Province (NWP) to access TOP services. This was a non-experimental, exploratory, descriptive and quantitative study. Structured interviews were conducted with 150 women who had used TOP services in phase 1, with 50 women who were unable to access TOP services in phase 2 and with 20 professional nurses providing TOP services in the NWP in phase 3. In phase 1, 96.0% (n=144) of the women needed transport to access TOP services, and 73.2% (n=109) indicated that nurses put women’s names on waiting lists, posing barriers to such access in the NWP. In phase 2, 92.0% (n=46) of these respondents had reportedly requested TOPs for the first time, but 89.0% (n=44) could not access TOP services. In phase 3, only 14 out of 19 designated facilities in the NWP, and only 20 nurses, provided TOP services during the study period. Out of the 20 interviewed nurses, 74.0% (n=14) regarded the Choice on Termination of Pregnancy Act, Act 92 of 1996 (CTOP Act) was being unclear requiring a revision. These professional nurses provided TOP services in NWP, by choice. Unless more facilities and more nurses can provide TOP services to the women of the NWP, these services will continue to remain inaccessible, necessitating the continued utilisation of illegal abortion services, in spite of the TOP Act’s prescriptions. It is also recommended that management will provide sufficient support and training opportunities for professional nurses working in TOP services in the NWP. / Health Studies / (D. Litt. et Phil. (Health Studies))
24

Développement du thermomètre Δ47 appliqué sur coccolithes : de la calibration en laboratoire à l’applicabilité au registre sédimentaire / Development of a coccolith-based Δ47 thermometer : from laboratory cultures to the applicability to the sedimentary archive

Katz, Amandine 05 July 2017 (has links)
Le géothermomètre Δ47 est basé sur la relation entre l’abondance des liaisons 13C–18O des carbonates et la température de calcification. Ce proxy contourne potentiellement les limites des autres thermomètres (δ18O, Mg/Ca) pour reconstruire les paléo-températures des océans, expliquant son développement exponentiel depuis dix ans. Cette thèse teste pour la première fois le potentiel et les limites de la thermométrie Δ47 sur les coccolithes, des nannofossiles calcaires produits par des organismes calcifiants dans la zone photique. Ces biominéraux calcitiques et ubiquistes constituent une part importante de l’archive sédimentaire. Des cultures in vitro nous ont permis d’établir que trois espèces de coccolithes actuelles enregistrent la même relation Δ47 – T que la calcite inorganique, alors qu'elles présentent de très larges effets vitaux en δ18O (±5‰). Nous concluons que ces espèces de coccolithes d'importance géologique ne présentent pas d’effets vitaux en Δ47. Nous avons ensuite appliqué le Δ47 à l’étude des sédiments enregistrant l’événement d’anoxie océanique du Toarcien (–183 Ma) au cours duquel les reconstructions de températures restent encore ambigües, notamment du fait de la méconnaissance de la composition isotopique en oxygène de l’eau de mer. Sur la base des données Δ47 acquises, nous proposons des températures élevées (de l’ordre de 36°C), mais restant relativement stables sur l'intervalle d'étude. En couplant ces températures aux données de δ18O des carbonates, nous suggérons une variation importante du δ18O de l'eau de mer dans le Bassin de Paris lors de la mise en place des faciès black shales. Enfin, sur des sédiments pélagiques subactuels, l’une des espèces étudiées présente des déséquilibres isotopiques en Δ47 non observés en culture et explicables par d’autres paramètres environnementaux comme l’intensité lumineuse. Cette thèse illustre le potentiel du thermomètre Δ47 des coccolithes en différents contextes, ouvrant un vaste champ d’application de reconstruction des paléo-environnements sur le Méso-Cénozoïque / The Δ47 geothermometer relies on the relationship between the 13C–18O abundance in carbonateand temperature of calcification. This proxy has the potential to overcome limitations of other thermometers(δ18O, Mg/Ca) to reconstruct oceanic paleotemperatures. This thesis evaluates for the first time the potentialand the limitations of the Δ47 thermometry of the coccoliths, the calcareous nannofossils produced byorganisms calcifying in the photic zone. These calcitic and ubiquitous biominerals represent an importantpart of the sedimentary archive. In vitro cultures allow us to establish that three modern coccoliths speciesrecord the same Δ47–T relation than inorganic calcite, although exhibiting substantial δ18O vital effects(±5‰). We conclude that these coccoliths species do not present any Δ47 vital effect. We subsequentlyapplied the Δ47 proxy to sediments from the Toarcian oceanic anoxic events (–183 Ma) during which thetemperatures reconstructions are still elusive, mainly due to the unknown oxygen isotopic composition ofseawater. On the basis of our Δ47 data, we infer relatively high, yet steady temperatures (around 36°C) duringthe examined interval. By combining these Δ47-derived temperatures to carbonate δ18O data, we can suggestdrastic change in the seawater δ18O composition in the Paris Basin at the onset of black shale deposition. Acore top calibration of Δ47 of coccoliths revealed that one of the studied cultured species exhibits Δ47disequilibrium that is accountable by other environmental parameters, such as light irradiance in the naturalenvironment. Thus, this thesis illustrates the potential of the coccolith Δ47 thermometer in different settings,opening a wide range of application to reconstruct the palaeoenvironments over the Meso-Cenozoic Eras
25

Recherche de Nouvelle Physique dans les événements à quatre quarks top avec le détecteur ATLAS du LHC

Paredes Hernandez, D. 13 September 2013 (has links) (PDF)
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/lambda 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 à √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.
26

Search for New Physics in events with 4 top quarks in the ATLAS detector at the LHC

Paredes Hernández, Daniela 13 September 2013 (has links) (PDF)
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.
27

Challenges encountered by women who requested termination of pregnancy services in the North West Province of South Africa

Mokgethi, Nomathemba Emily Blaai 08 1900 (has links)
In 1996 the South African government legalised the termination of pregnancy (TOP) services, allowing women to choose to terminate unplanned pregnancies at designated facilities. Although TOP services are available, pregnant women continue to use illegal abortion services, with potentially life-risking consequences. The purpose of this study was to identify challenges encountered by women requesting TOP services, and to make recommendations for improved policies and practices, enabling more women in the North West Province (NWP) to access TOP services. This was a non-experimental, exploratory, descriptive and quantitative study. Structured interviews were conducted with 150 women who had used TOP services in phase 1, with 50 women who were unable to access TOP services in phase 2 and with 20 professional nurses providing TOP services in the NWP in phase 3. In phase 1, 96.0% (n=144) of the women needed transport to access TOP services, and 73.2% (n=109) indicated that nurses put women’s names on waiting lists, posing barriers to such access in the NWP. In phase 2, 92.0% (n=46) of these respondents had reportedly requested TOPs for the first time, but 89.0% (n=44) could not access TOP services. In phase 3, only 14 out of 19 designated facilities in the NWP, and only 20 nurses, provided TOP services during the study period. Out of the 20 interviewed nurses, 74.0% (n=14) regarded the Choice on Termination of Pregnancy Act, Act 92 of 1996 (CTOP Act) was being unclear requiring a revision. These professional nurses provided TOP services in NWP, by choice. Unless more facilities and more nurses can provide TOP services to the women of the NWP, these services will continue to remain inaccessible, necessitating the continued utilisation of illegal abortion services, in spite of the TOP Act’s prescriptions. It is also recommended that management will provide sufficient support and training opportunities for professional nurses working in TOP services in the NWP. / Health Studies / (D. Litt. et Phil. (Health Studies))

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