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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.
1

Théorie de l'homotopie des algèbres sur un PROP / Homotopy theory of algebras over a PROP

Yalin, Sinan 13 September 2013 (has links)
Le but de cette thèse est de mettre en place une théorie d’homotopie générale pour les catégories de bigèbres différentielles graduées. Une première partie est consacrée au cas des catégories de bigèbres définies par un couple d’opérades en distribution. Les bigèbres classiques, les bigèbres de Lie, les bigèbres de Poisson fournissent des exemples de telles structures de bigèbres. Le résultat principal de cette partie montre que la catégorie des bigèbres associée a un couple d’opérades en distribution hérite d’une structure de catégorie de modèles. La notion de PROP donne un cadre pour étudier des structures de bigèbres générales, impliquant des opérations à plusieurs entrées et plusieurs sorties comme générateurs de la structure, par opposition aux opérades en distribution qui ne permettent de coder que des opérations à une seule entrée ou à une seule sortie seulement. Les PROPs forment une catégorie, dans laquelle on peut définir une notion d’objet cofibrant avec de bonnes propriétés homotopiques.La seconde partie de la thèse est consacrée à la théorie homotopique des bigèbres sur un PROP. Le résultat principal de la thèse est que les catégories de bigèbres associées à des PROPs cofibrants faiblement équivalents ont des catégories homotopiques équivalentes. En fait, on prouve un théorème plus précis qui donne une équivalence au niveau des localisations simpliciales des catégories. Notre théorème entraine que la catégorie des bigèbres associée à une résolution cofibrante d’un PROP donné P définit une notion de bigèbre à homotopie près sur P indépendante du choix de la résolution, et permet de donner un sens à des problèmes de réalisation homotopiques dans ce cadre. / The purpose of this thesis is to set up a general homotopy theory for categories of differential graded bialgebras. A first part is devoted to the case of bialgebras defined by a pair of operads in distribution. Classical bialgebras, Lie bialgebras and Poisson bialgebras provide examples of such bialgebra structures. The main result of this part asserts that the category of bialgebras associated to a pair of operads in distribution inherits a model category structure. The notion of a PROP provides a setting for the study of general bialgebras structures, involving operations with multiple inputs and multiple outputs as generators of the structure, in contrast to operads in distribution which only encode operations with either one single input or one single output. PROPs form a category, in which one can define a notion of cofibrant object with good homotopical properties. The second part of the thesis is devoted to the homotopy theory of bialgebras over a PROP. The main result of the thesis asserts that the categories of bialgebras associated to weakly equivalent cofibrant props have equivalent homotopy categories. We actually prove a more precise theorem asserting that this equivalence holds at the level of a simplicial localization of the categories. Our theorem implies that the category of bialgebras associated to a cofibrant resolution of a given PROP P defines a notion of bialgebra up to homotopy over P independent of the choice of the resolution, and enables us to give a sense to homotopical realization problems in this setting.
2

The Luminescence Properties of Diketonato-Europium Complexes

Yeh, Yi-Yen 09 August 2002 (has links)
Europium complex is a promising candidate for organic electroluminescent (EL) material due to its sharp emission band. Several diketone ligands bearing different substituents (substituents¡×CH3, Ph, CF3, thiophene) as well as phenanthroline and its derivatives (substituents¡×CH3, Ph, NO2) were used to synthesize our target series of Europium complexes. The complexes were identified by means of NMR, EA, MS, and single-crystal X-ray analysis. We report here the structural influence on photoluminescence (PL), UV-Vis and thermal properties of these Eu complexes. Within the series, Eu(TTFA)3(Bath) showed the highest fluorescence in THF solution. A efficient red electroluminescence (sharp emission at 616 nm) was obtained in the organic electroluminescent device using Eu(TTFA)3(Bath) doped into CBP. The external quantum efficiency and maximum luminance of the device were 1.022¢M and 1295 cd/m2, respectively.
3

Analyzing the Homodimeric and Heteromeric Nature of the Osmosensory Transporter ProP from Escherichia coli

Sahtout, Naheda Mohamad Fayez 22 August 2013 (has links)
In this study, the homodimeric and heteromeric nature of ProP, an H+/solute symporter, from E. coli was analyzed. The measured initial rates of proline uptake via ProP-His6 and His6-ProP indicated that as the growth medium osmolality increased, the assay medium osmolality required for half maximal transport activity (Π½/RT) increased and the maximal uptake rate (Amax) decreased. The oligomeric state of ProP, as determined by Blue Native PAGE, showed that both monomeric and dimeric forms of the transporter were present in wild type and cardiolipin deficient bacteria expressing ProP, ProP-His6 or His6-ProP, after culturing in low or high growth medium osmolality. The BACTH System was used to confirm the homodimeric ProP-ProP interaction and to verify the heteromeric interaction between ProP and YdhP. Initial rates of proline uptake via ProP and Western blots indicated that replacement of the ydhP locus with a kanamycin cassette had no effect on ProP function or expression.
4

Evaluating factors that affect copper tasting sensitivity in drinking water

Cuppett, Jonathan David 27 May 2005 (has links)
Corrosion of household copper plumbing infrastructure can cause pipe failure and lead to elevated levels of copper in drinking water which can exceed the USEPA health based standard for copper in drinking water of 1.3 mg/L Cu. The purpose of this study was to determine taste thresholds of copper in different types of water, analyze how copper chemistry can affect tasting, determine if common disinfectants influence the taste of copper and evaluate genetic links to copper sensitivity. A one-out-of-five test was used to define thresholds, evaluate disinfectant influences, and examine copper chemistry differences. A difference from control test was used to analyze soluble copper tasting and a one solution test with visual classification was used to discriminate 6-n-propylthiouracil (PROP) taster status. Solutions containing copper sulfate (0.05 – 8 mg/l Cu) were prepared in distilled water, mineral water of varying pH and mineral water with disinfectant added. Geometric mean copper taste thresholds were 0.48 mg Cu/l and 0.41mg Cu/l in distilled and mineral water pH 7.4 respectively. Logistic regression copper taste thresholds were 1.50 mg Cu/l and 1.96 mg Cu/l in distilled and mineral water pH 7.4 respectively. Soluble copper was readily tasted while particulate copper was poorly tasted. Chlorine and chloramines dosed at typical tap water levels had no significant effect on panelists' tasting abilities for water containing 1 mg/l total copper. Geometric mean copper thresholds values did not correlate with (PROP) status so PROP sensitivity would not be a good indicator for copper sensitivity. / Master of Science
5

Är du en super-taster? : Sensorisk analys av beska smakpreferenser.

Gelberg, Johan, Anjou Monero, Isaac January 2018 (has links)
No description available.
6

INFLUENCES OF WATER QUALITY AND HABITAT RELATIONSHIPS ON THE BURROW DENSITY OF SPHAEROMA TEREBRANS

Unknown Date (has links)
Sphaeroma terebrans, is an ecological engineer that can significantly modify the habitat of free-hanging aerial prop roots of Rhizophora mangle. The wood-boring isopod extensively burrows into red mangrove aerial prop roots for habitat and protection from desiccation and access to phytoplankton. However, the burrows created have major consequences on the mangrove habitat and aerial root inhabitants. It has been suggested that sessile species residing in aerial root communities can either encourage or discourage colonization by S. terebrans. Abiotic factors can affect the distribution and abundance of mangrove forest and are the same factors which determine the composition and abundance of organisms living on the roots. Surveys indicated that burrowing damage was found predominately in the first 20 cm of the root tip. Exploratory Structural Equation Modeling (SEM) was used to test multivariate hypothesized models looking at habitat relationships with S. terebrans in aerial root communities. Temperature and dissolved oxygen were shown to be important drivers in affecting submerged root length of aerial roots. Ultimately, the indirect effects between these parameters proved to be stronger in influencing the barnacle – isopod association, which causes direct negative effects on submerged root length. Colonial tunicates showed weak effects in masking aerial roots from the damaging barnacle – isopod association. Chlorophyll a was used as a proxy for phytoplankton biomass and proved to be less influential than habitat protection for S. terebrans. Results highlight the need for experimentation in addition to modeling in order to determine the mechanisms influencing aerial root community inhabitants and further effects on the habitat. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection
7

The Influence of Dietary Flavanol Mean Degrees of Polymerization on Sensory Preference Trends and the Metabolic Syndrome

Griffin, Laura E. 05 December 2018 (has links)
According to the Centers for Disease Control, roughly 9.4% of the US population is diabetic, and at least 35% of the US population has metabolic syndrome. These diseases are associated with increased mortality risk, reduced quality of life, and altered taste perception of foods. With increased occurrence of these metabolic diseases, there is a greater need for research oriented towards using lifestyle modifications to combat illness. A relationship between flavanol consumption, health benefits, and taste perception has been well documented. Dietary flavanols are secondary plant metabolites that exist naturally in a wide array of polymerization states. The mechanisms behind the protective effects of flavanols are not entirely understood, particularly when considering how the mean degrees of polymerization (mDP), or average compound size, impacts the health benefits. Moreover, it is known that flavanol mDP influences the sensory attributes of flavanol-rich foods including bitterness and astringency. It is known that obesity and sensitivity to bitterness both influence perception of certain taste attributes such as sweetness and bitterness. The influence of these bitter and astringent sensations determined by flavanol mDP on consumer preferences for flavanol-rich products remains unknown. These influences on preference pose potential barriers to consumption, resulting in the loss of health benefits. The objectives of the research detailed here were i) to determine the effect of dietary consumption of small to medium-sized flavanols on markers of metabolic syndrome that were brought on by diet-induced obesity, ii) to determine how flavanol mDP influences the consumer perception and liking of flavanol-rich, wine-like products based on differences in consumer phenotype, and iii) to explore the potential to manipulate mDP of wine using traditional winemaking techniques. By way of an in vivo mouse model, it was observed that regardless of mDP, flavanols delivered at low dose, as part of a high-fat diet, reduced adipose-derived inflammatory cytokine production but did not prevent associated weight and fat gain. This suggests that small to medium sized flavanols may, at low dose, delay the onset of the pro-inflammatory state, which could ultimately protect against metabolic derangements associated with obesity and diabetes. Regarding the consumer acceptance of wine-like products made from flavanols of different mDP, and therefore different in bitterness and astringency intensity, it was observed in a consumer panel (n = 102) that when segmenting the panelists by body fat % and BMI classification, increased adiposity was associated with decreased ability to differentiate wine samples made with flavanols of different mDP. Moreover, differences in liking and ability to differentiate bitterness and astringency intensities were not as pronounced when segmenting the panelists based on bitterness sensitivity. This suggests that obesity may impact preference for flavanol-rich foods more so than sensitivity to flavor attributes associated with these products. Finally, in an exploratory effort to manipulate mDP of red and rosé wines using traditional winemaking techniques, no differences in mDP were observed in young wines, but significant differences in flavanol concentration were detected. It is hypothesized that aging of these wines could lead to greater differences in mDP, especially for those that had a high flavanol concentration at baseline. Future work will continue to build off these studies so that flavanol-rich products such as red wine can be optimized for health benefits and consumer acceptability of dietary polyphenols. / Ph. D. / According to the Centers for Disease Control, roughly 9.4% of the US population is diabetic, and at least 35% of the US population has metabolic syndrome. These diseases are associated with increased mortality risk, reduced quality of life, and altered taste perception for certain food types. With increased occurrence of these metabolic diseases, there is a greater need for research oriented towards using lifestyle modifications to combat illness. Dietary flavanols, which are potent antioxidants derived from plants, are being explored for their ability to mitigate chronic disease. They exist naturally in a wide variety of sizes and structures depending on plant of origin, growing conditions, and food processing conditions. It is believed that the size of these compounds impacts their health effects and influences their taste profile; smaller compounds are more bitter while larger compounds are more astringent. The purpose of this research was to determine the effect of flavanol supplementation on markers of the metabolic syndrome and how differences in taste due to differences in flavanol size influence consumer liking and perception of winelike products. It was determined in this study that dietary flavanols, delivered at low dose in the context of a high-fat diet can slightly improve fasting blood glucose levels and prevent inflammation. When examining consumer preferences for wines made from dietary flavanols that are distinctly different in terms of bitterness and astringency, it was determined that overall, consumers liked wines that were less intense in terms of bitterness and astringency. However, when examining consumers classified as having a high body fat percentage or high BMI, their ability to differentiate the wines was decreased compared to lean counterparts. These findings suggest that dietary flavanol supplementation at a physiologically relevant dose may improve symptoms of diabetes and metabolic syndrome. Future work confirming these observations in humans is warranted, as are studies devoted to better understanding of the taste preferences of the obese population. This will allow for optimization of flavanol-rich foods that maximize health benefit while also being palatable to consumers.
8

Värnpliktens vara eller icke vara : En argumentationsanalys av riksdagsdebatten om försvarsproposition 2008/09:140, angående Svenska försvarsmaktens framtida personalförsörjning / Compulsory Military service; to be or not be

Karlberg, Christoffer January 2010 (has links)
<p>Sweden's government says in the bill 2008/09: 140 that military service should be suspended and replaced with a system based on voluntary recruitment. In the essay, I will make an argument analysis of the parliamentary debate on the bill from the 12th of June 2009 with the following questions: On what is the different side’s argument based on? Are the arguments essentially and factually substantiated? Is there a clear political party tendency among the for-/counter arguments? The method is a "Pro et contra" analysis, a logical systematization of the arguments. The analysis will take start in the headline; Conscription should be suspended in favour of a voluntary system based on contract employed soldiers. The presentation of arguments in the analysis will be guided by the chronological order. The main argument against the bill is a belief that this system will generate greater costs. Furthermore, results from studies performed on other countries that have recently changed from compulsory military service to contract employed soldiers shows difficulties in recruiting and retaining staff in a voluntary system. Moreover it is noted that the increase in battle readiness that this new system means, would be completely unjustified in view of prevailing threats against Sweden. Finally, it is argued that the common support is at risk when Sweden's defence affairs no longer become an obligation for every individual to contribute. The arguments for the bill believe that we need forces that are fit to use and available, to meet the new threats that is emerging and in which Sweden's participation in international missions is the focal point. The conflict in the debate is based mostly in the ideological distinctions and as a result of these also economic contradictions. As a direct consequence of this, most of the arguments are not substantiated with facts. However, there is traceability to arguments that historically have been used to justify the introduction of either of the systems. There is a clear party political tendency in the debate. Government parties stay united and the opposition parties are slightly more dispersed in their argumentation but still against the bill.</p>
9

Värnpliktens vara eller icke vara : En argumentationsanalys av riksdagsdebatten om försvarsproposition 2008/09:140, angående Svenska försvarsmaktens framtida personalförsörjning / Compulsory Military service; to be or not be

Karlberg, Christoffer January 2010 (has links)
Sweden's government says in the bill 2008/09: 140 that military service should be suspended and replaced with a system based on voluntary recruitment. In the essay, I will make an argument analysis of the parliamentary debate on the bill from the 12th of June 2009 with the following questions: On what is the different side’s argument based on? Are the arguments essentially and factually substantiated? Is there a clear political party tendency among the for-/counter arguments? The method is a "Pro et contra" analysis, a logical systematization of the arguments. The analysis will take start in the headline; Conscription should be suspended in favour of a voluntary system based on contract employed soldiers. The presentation of arguments in the analysis will be guided by the chronological order. The main argument against the bill is a belief that this system will generate greater costs. Furthermore, results from studies performed on other countries that have recently changed from compulsory military service to contract employed soldiers shows difficulties in recruiting and retaining staff in a voluntary system. Moreover it is noted that the increase in battle readiness that this new system means, would be completely unjustified in view of prevailing threats against Sweden. Finally, it is argued that the common support is at risk when Sweden's defence affairs no longer become an obligation for every individual to contribute. The arguments for the bill believe that we need forces that are fit to use and available, to meet the new threats that is emerging and in which Sweden's participation in international missions is the focal point. The conflict in the debate is based mostly in the ideological distinctions and as a result of these also economic contradictions. As a direct consequence of this, most of the arguments are not substantiated with facts. However, there is traceability to arguments that historically have been used to justify the introduction of either of the systems. There is a clear party political tendency in the debate. Government parties stay united and the opposition parties are slightly more dispersed in their argumentation but still against the bill.
10

Simulation of the deformation of a stope support design / Abraham Johannes Laubscher

Laubscher, Abraham Johannes January 2014 (has links)
Supported stope mining is one of the most common types of mining in the modern day gold mining industry. The excavated regions, where ore is extracted, are supported with a combination of roof-bolting, timber packs, backfill, timber props and mechanical prop technologies. In order to install a support system that will be able to absorb the energy released by the elastic movement of the surrounding rock mass and support the unstable hanging wall, it is necessary for the rock engineer to know how the individual types of support will react to different load conditions in order to design a safe support system. Current support systems are developed using knowledge from past experience and trial and error processes. These are expensive and time consuming methods that can possibly be improved and made more cost effective by using modern design techniques. A study was conducted to determine the feasibility of the application of Finite Element Modelling (FEM) to the deformation of a modern support unit under specified quasi-static and dynamic stope load conditions with the view to assist in the prediction of the operational performance of support units that cannot be experimentally tested due to a lack of test equipment, capabilities and facilities. The study was extended by investigating the theoretical possibility of buckling due to an impact load on the prop and the performance of the prop. To achieve this, a simulation was carried out using ANSYS™ transient structural software to determine whether it is possible to simulate the performance curve of a prop. Computerised methods were used to determine the possibility of failure due to buckling and the implications of buckling, if it occurs, on the performance of a specific support prop design. In summary this study proved that it is possible to simulate the performance curve of a friction prop design in order to compare the result obtained with the required performance, provided that the correct friction coefficients between prop mating surfaces are known. It also presents a methodology to investigate the theoretical effect of high velocity impact load on the buckling potential of a friction prop design and slender columns in general, which is highly applicable to these types of support. The methodologies used in this study can be applied to different designs of friction props, and possibly reduce the development costs and implementation time of these types of support units. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

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