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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

Changing Climate and Geographical Patterns of Taxonomic Richness

Vázquez Rivera, Héctor January 2014 (has links)
The geographic variation of taxonomic richness may be directly determined by climate through contemporaneous/ecological processes, versus other (e.g., historical/evolutionary processes) that happen to be collinear with contemporaneous climate. In Chapter 1 I evaluated hypotheses from both groups of explanations in North America. If contemporaneous climate controls patterns of richness, then richness should vary with climate through time in the same way that richness varies with current climate through space. Over the last ca. 11,000 yr, richness-temperature relationships remained reasonably constant. Between 12,000 and 14,000 yr BP, when climate fluctuated rapidly, richness gradients as a function of temperature were significantly shallower. If historical climate over the last 21,000 years determines patterns of richness, then historical climate should be a better predictor of richness than contemporaneous climate. I rejected historical-climate as a better predictor of richness. Contemporaneous climate stands as the most plausible explanation for contemporaneous patterns of richness, at least over the last 11,000 yr. In Chapter two, I tested the prediction that richness of most taxa should increase with temperature in all but the warmest and driest areas. Climate warming during Pleistocene-Holocene transition led richness increases in wet areas, but richness declines in dry regions, as expected from current richness-climate relationships. A decline in small mammal species richness in Northern California since the late Pleistocene was expected from the current richness-climate relationship for this group in North America. These results contest the view that future global warming may lead to species extinction rates that would qualify as the sixth mass extinction in the history of the earth. In chapter three, I first tested the hypothesis that richness gradients mainly reflect the sum of individual species climatic tolerances. I tested this hypothesis for birds, mammals and trees native to eastern North America (ENA, where there are no major barriers to dispersal). The number of species present in any given area in ENA is usually much smaller than the number of species in the continental pool that tolerate the climatic conditions in that area. Second, I tested several explanations for patterns of unfilled potential richness. Unfilled potential richness is inconsistent with postglacial dispersal lags, climatic variability since the Last Glacial Maximum, or with biotic interactions. In contrast, unfilled richness is highly consistent with a probabilistic model of species climate occupancy. Individual species climatic tolerances is not the process generating the main current patterns of richness, nor are post-glacial dispersal lags, climatic variability since the LGM or biotic interactions. This thesis is consistent with the hypothesis that contemporaneous climate directly controls spatial patterns of richness. Generally, there seems to be little need to invoke historical processes as determinants of current gradients of richness.
2

Empty and filled rhythms:An inquiry into the different cognitive processing of vocal and instrumental rhythms

Cheong, Yong Jeon 23 August 2013 (has links)
No description available.
3

ECONOMIC IMPACT OF WASTE IN PRESCRIBING, DISPENSING, AND MEDICATION CONSUMPTION IN THE UNITED STATES

Almanie, Sarah 01 January 2015 (has links)
Abstract ECONOMIC IMPACT OF WASTE IN PRESCRIBING, DISPENSING, AND MEDICATION CONSUMPTION IN THE UNITED STATES By Sarah A. Almanie, M.S. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science at Virginia Commonwealth University. Virginia Commonwealth University, 2015. Major Director: David A. Holdford, R.Ph., M.S., Ph.D., FAPhA Professor Department of Pharmacotherapy and Outcomes Science OBJECTIVES: This research examines waste associated with the medication use process which consists of unfilled prescriptions, abandoned prescriptions, or unused prescription medications. The aim of this study is to quantify the direct medical costs of medication waste in delivery of care in the United States. METHODS: A review of published literature and data from the 2012 Medical Expenditure Panel Survey was used to quantify the number of prescriptions wasted at different stages of the medication prescribing and use process and the associated costs were calculated. RESULTS: In 2012, more than 26 million prescriptions were either unfilled or abandoned, and more than 225 million resulted in dispensed medications that were not used. The total cost of this waste was estimated at $30.4 billion. CONCLUSIONS: Patients who do not fulfill their role in the medication use process cause significant, avoidable costs to the health care system beyond the health outcomes not achieved.
4

Estudo do efeito do não preenchimento das juntas verticais e eficiência do graute na resistência da alvenaria estrutural de blocos cerâmicos / Study of the effect of unfilled vertical joints and efficiency of grout in the strength of structural masonry of clay bricks

Miranda, Larissa de Almeida 31 October 2012 (has links)
No contexto do crescimento do processo construtivo em alvenaria estrutural, destaca-se o uso do bloco cerâmico consolidado com a criação de sua norma específica de projeto, execução e controle de obras, a NBR 15812, partes 1 e 2 (ABNT, 2010). Desde a difusão da alvenaria estrutural, mudanças nas técnicas construtivas vêm ocorrendo, como por exemplo, o não preenchimento das juntas verticais de assentamento dos blocos. Outra prática que tem sido utilizada é o grauteamento da alvenaria. No entanto, ainda não está estabelecido se o não preenchimento da junta vertical compromete o desempenho da alvenaria ou qual a resistência necessária ao graute para aumentar a resistência da alvenaria. Diante disto, o trabalho objetiva contribuir com o estudo do não preenchimento das juntas verticais avaliando o seu efeito na resistência à compressão e ao cisalhamento de pequenas paredes e também pesquisar a influência do graute em prismas e pequenas paredes submetidos à compressão. Com as análises dos resultados pode-se concluir que o não preenchimento das juntas verticais não exerceu influência nos valores de resistência à compressão e também nos módulos de elasticidade longitudinal das pequenas paredes ensaiadas. No entanto, influenciou significativamente os resultados do ensaio de compressão diagonal para avaliar a resistência ao cisalhamento, apesar do módulo de deformação transversal ter sido considerado equivalente. Os resultados do estudo preliminar em prismas mostraram que a média da resistência à compressão em relação à área bruta do prisma grauteado, utilizando o Graute A e o Graute C, foi equivalente à média do prisma oco. Assim, foi escolhido o Graute A para a confecção de pequenas paredes e prismas. Pode-se concluir com os resultados das pequenas paredes grauteadas que houve um aumento significativo da resistência à compressão em relação à área bruta, mas em relação à área líquida, os valores encontrados foram equivalentes às pequenas paredes ocas. Portanto o aumento na resistência à compressão na pequena parede foi proporcional ao ganho de área dado pelo grauteamento de seus vazios, diferentemente do comportamento observado nos prismas. / In the context of growth of structural masonry construction process, it highlight the use of the ceramic block consolidated with the creation of its specific standard of design, execution and control, the NBR 15812, Parts 1 and 2 (ABNT, 2010). Since the propagation of structural masonry, changes have occurred in the construction techniques, such as don\'t fill the vertical joints of the masonry wall. Another technique that has been used is the grouted masonry. However, it is not yet established if the unfilled vertical joints compromise the performance of masonry or which strength is necessary to the grout to increase the strength of the masonry. Therewith, the paper aims to contribute to the study of unfilled vertical joints by analyzing its effect on compressive strength and shear strength of small walls and also investigate the influence of grout in prisms and small walls under compression. With the analysis of the results we can conclude that do not fill the vertical joints had no influence on the values of compressive strength and elastic modulus of the small walls tested. However, it significantly affects the results of the diagonal compression test to evaluate shear strength, despite the shear elastic modulus being considered equivalent. The results of the preliminary study in prisms showed that the average of the compressive strength in relation to the gross area of the grouted prism using the Grout A and the Grout C were equivalent to the average of hollow prism. Thus, small walls and prisms with the Grout A were made. It can be concluded with the results of grouted small walls that there was a significant increase in compressive strength with respect to the gross area, but in relation to the net area, were similar to the hollow small wall. Therefore the increase in the compressive strength in a small wall is proportional to the gain of the area given by the grout, unlike the behavior observed in the prisms.
5

Estudo do efeito do não preenchimento das juntas verticais e eficiência do graute na resistência da alvenaria estrutural de blocos cerâmicos / Study of the effect of unfilled vertical joints and efficiency of grout in the strength of structural masonry of clay bricks

Larissa de Almeida Miranda 31 October 2012 (has links)
No contexto do crescimento do processo construtivo em alvenaria estrutural, destaca-se o uso do bloco cerâmico consolidado com a criação de sua norma específica de projeto, execução e controle de obras, a NBR 15812, partes 1 e 2 (ABNT, 2010). Desde a difusão da alvenaria estrutural, mudanças nas técnicas construtivas vêm ocorrendo, como por exemplo, o não preenchimento das juntas verticais de assentamento dos blocos. Outra prática que tem sido utilizada é o grauteamento da alvenaria. No entanto, ainda não está estabelecido se o não preenchimento da junta vertical compromete o desempenho da alvenaria ou qual a resistência necessária ao graute para aumentar a resistência da alvenaria. Diante disto, o trabalho objetiva contribuir com o estudo do não preenchimento das juntas verticais avaliando o seu efeito na resistência à compressão e ao cisalhamento de pequenas paredes e também pesquisar a influência do graute em prismas e pequenas paredes submetidos à compressão. Com as análises dos resultados pode-se concluir que o não preenchimento das juntas verticais não exerceu influência nos valores de resistência à compressão e também nos módulos de elasticidade longitudinal das pequenas paredes ensaiadas. No entanto, influenciou significativamente os resultados do ensaio de compressão diagonal para avaliar a resistência ao cisalhamento, apesar do módulo de deformação transversal ter sido considerado equivalente. Os resultados do estudo preliminar em prismas mostraram que a média da resistência à compressão em relação à área bruta do prisma grauteado, utilizando o Graute A e o Graute C, foi equivalente à média do prisma oco. Assim, foi escolhido o Graute A para a confecção de pequenas paredes e prismas. Pode-se concluir com os resultados das pequenas paredes grauteadas que houve um aumento significativo da resistência à compressão em relação à área bruta, mas em relação à área líquida, os valores encontrados foram equivalentes às pequenas paredes ocas. Portanto o aumento na resistência à compressão na pequena parede foi proporcional ao ganho de área dado pelo grauteamento de seus vazios, diferentemente do comportamento observado nos prismas. / In the context of growth of structural masonry construction process, it highlight the use of the ceramic block consolidated with the creation of its specific standard of design, execution and control, the NBR 15812, Parts 1 and 2 (ABNT, 2010). Since the propagation of structural masonry, changes have occurred in the construction techniques, such as don\'t fill the vertical joints of the masonry wall. Another technique that has been used is the grouted masonry. However, it is not yet established if the unfilled vertical joints compromise the performance of masonry or which strength is necessary to the grout to increase the strength of the masonry. Therewith, the paper aims to contribute to the study of unfilled vertical joints by analyzing its effect on compressive strength and shear strength of small walls and also investigate the influence of grout in prisms and small walls under compression. With the analysis of the results we can conclude that do not fill the vertical joints had no influence on the values of compressive strength and elastic modulus of the small walls tested. However, it significantly affects the results of the diagonal compression test to evaluate shear strength, despite the shear elastic modulus being considered equivalent. The results of the preliminary study in prisms showed that the average of the compressive strength in relation to the gross area of the grouted prism using the Grout A and the Grout C were equivalent to the average of hollow prism. Thus, small walls and prisms with the Grout A were made. It can be concluded with the results of grouted small walls that there was a significant increase in compressive strength with respect to the gross area, but in relation to the net area, were similar to the hollow small wall. Therefore the increase in the compressive strength in a small wall is proportional to the gain of the area given by the grout, unlike the behavior observed in the prisms.
6

Synthesis and mechanical properties of elastomers made by sequential-IPNs / Synthèses et propriétés mécaniques d'élastomères produites par séquence-IPNS

Limpanichpakdee, Thitima 14 November 2017 (has links)
Récemment, une nouvelle technique pour renforcer les élastomères acryliques non chargés a été développée. L'élastomère a été préparé par séquences de gonflement par du monomère acrylique et polymérisation radicalaire en faisant des réseaux interpénétrés. Le prétirement des chaines du premier réseau créent des liaisons sacrificielles qui améliorent de manière significative les propriétés mécaniques de l’élastomère sans modifier sa Tg. Il est donc intéressant d’étendre cette méthode à d’autres familles d’élastomères. Ainsi, dans cette étude, la stratégie des réseaux interpénétrés a été appliquée à deux matériaux intéressants. Premièrement, un élastomère silicone a été synthétisé en utilisant une polymérisation par polycondensation par réaction d'hydrosilylation qui est significativement différente de la polymérisation utilisée pour les réseaux acryliques. Les réseaux multiples ont été ensuite synthétisés en gonflant ce réseau avec des précurseurs de petite masse et un faible pourcentage de réticulant D4H. Ces réseaux multiples en silicone ont les propriétés d’un élastomère classique, avec une énergie de rupture améliorée d’environ 100%. Deuxièmement, des particules coeur-ecorce formés de copolymères dibloc amphiphiles de poly(acide acrylique)-b-poly(acrylate de n-butyle) ou PAA-b-PBA ont été synthétisés par auto-assemblage simultané par polymérisation RAFT et préparés sous la forme de films. Ensuite, les films ont été utilisés comme des charges polymères en poly (acrylate de butyle) en utilisant une technique de réseau interpénétrés multiples. Nous avons réussi pour la première fois à renforcer l'élastomère par des particules de latex. Grâce à cette stratégie d'interpénétration qui distribue des particules de latex de manière très homogène dans l’élastomère, les films interpénétrés montrent de bonnes caractéristiques mécaniques, une résistance à la fracture et une ténacité extrêmement élevées en utilisant moins de 1% de PAA vitreux et pas de réticulant ajouté dans la particule renforçante. / Recently, a new technique to reinforce unfilled acrylic elastomers has been established. The elastomer was prepared by sequential free radical polymerization and swelling of acrylic monomers making interpenetrated networks. By introducing sacrificial bonds, the elastomer had significantly enhanced mechanical properties without changing the Tg of the material. We extended this method to two different elastomeric system to probe its generality. First, a silicone elastomer was synthesized by using polycondensation polymerization via a hydrosilylation reaction which is significantly different from the free radical polymerization used for acrylic networks. The multiple networks were synthesized by sequential swelling and polymerization steps with low molecular weight preducrosrs and a small amount of D4H crosslinker. The resulting silicone multiple networks were fully elastic elastomer with a mechanical toughness improved by about 100%. Second, core-shell latexes made of amphiphilic diblock copolymers Poly(acrylic acid)-block-poly(butyl acrylate) or PAA-b-PBA were synthesized by RAFT polymerization induced self-assembly and prepared into thin films. Different types of core-shell latexes and crosslinked latexes were synthesized and characterized both in the aqueous state and in the dry film state. The films were then used as a polymeric filler to a poly(butyl acrylate) by using the interpenetrated network technique. We succeeded for the first time to reinforce elastomers by latex particles. Thanks to interpenetrated networks strategy which distributed homogenously latex particles though the entire material, the interpenetrated films show extremely enhanced mechanical characteristics, fracture energy and toughness by using less than 1 % of glassy PAA content and no crosslinker in the reinforcing particles.

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