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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

Modulation of Synaptic Vesicle Pools by Serotonin and the Spatial Organization of Vesicle Pools at the Crayfish Opener Neuromuscular Junction

Bilkey, Jessica 01 May 2015 (has links)
The crayfish claw opener neuromuscular junction (NMJ) is a biological model for studying presynaptic neuromodulation by serotonin and synaptic vesicle recycling. Serotonin acts on crayfish axon terminals to increase the release of the neurotransmitter glutamate, but a complete understanding of its mechanisms of action are unknown. In order to sustain enhanced neurotransmission over long periods of time, it was hypothesized that serotonin recruits (activates) a population of previously non-recycling vesicles to become releasable and contribute to neurotransmission. To determine if serotonin activates a distinct population of synaptic vesicles, FM1-43 fluorescence unloading experiments were performed on crayfish excitatory opener axon terminals. These experiments could not resolve a serotonin-activated population of synaptic vesicles, but instead revealed that synaptic vesicles change behaviour in axon terminals independent of serotonin, with vesicles becoming less likely to exocytose and unload FM1-43 dye over time. The change in behaviour was hypothesized to be due to conversion of vesicles from a recycling (releasable) status to a reserve (reluctant to release) status. Synaptic vesicle pool localization was then tested using photoconversion of FM1-43 and transmission electron microscopy techniques. The spatial location of FM1-43-labeled vesicles fixed 2 minutes following 20 Hz stimulation did not reveal retention of vesicles specifically near release sites and the distribution of FM1-43-labeled vesicles was not significantly different between early (2 min) and late (180 min) time points. Terminals fixed 30 seconds following stimulation, however, contained numerous endosome-like structures - the most frequently observed structures resembled large vesicles, which were the equivalent of 2-5 regular vesicle sizes. These results suggest that crayfish axon terminals recycle vast amounts of membrane in response to sustained 20-Hz stimulation and endocytosis appears to occur via multiple routes with the most common being through large vesicle intermediates. / Graduate
22

Endogenous Nucleotide Pools in Growing Cells of Azotobacter Vinelandii

Lee, Yick-Shun 08 1900 (has links)
The objective of this investigation was to examine the changes in the nucleotide pools of Azotobacter vinelandii during the growth cycle. Endogenous ribonucleotides were extracted from A. vinelandii using trichloroacetic acid (TCA; 12% w/v). The 5' mono-, di- and triphosphates of adenine, guanine, uracil and cytosine were separated and quantified by anion-exchange high performance liquid chromatography. Results indicated that the adenylate energy charge of A. vinelandii paralleled the growth rate during exponential phase and that it declined rapidly as the stationary phase was reached. In addition, the amount of each nucleotide in A. vinelandii tended to increase in the logarithmic phase and decrease in the stationary phase in a similar manner to the energy charge.
23

Diagnóstico das piscinas de uso coletivo no município de São Carlos - SP / Diagnostic of collective use swimming pools in the city of São Carlos - SP

Santos, Denise Conceição de Gois 30 July 2004 (has links)
Este trabalho de pesquisa acadêmica, precipuamente, objetivou avaliar por amostragem, a qualidade sanitária das piscinas de uso coletivo da cidade de São Carlos, SP, com base nas legislações vigentes. O Código Nacional de Saúde, no artigo 44 dá realce ao planejamento, construção e uso das piscinas coletivas sujeitas ao controle das autoridades sanitárias competentes. O Código Sanitário do Estado de São Paulo, no decreto 12.342 de 27 de setembro de 1978, apresenta especificações para as águas de piscina. Para avaliação das instalações anexas foram estudados projetos, construção, operação de equipamentos, manutenção da área construída; foram feitas, também, vistorias das referidas instalações das piscinas propriamente ditas. Com base na legislação estadual e nos padrões da CETESB (Companhia de Tecnologia e Saneamento Ambiental), foram estudados regulamentos quanto a pessoal de apoio; e por meio de parâmetros físicos, químicos e bacteriológicos foi avaliada a qualidade da água de cada unidade amostral do universo de pesquisa deste trabalho porque, em conjunto, os anexos, o tanque de recreação e a água são responsáveis por problemas de saúde pública. Em São Carlos, das 28 piscinas de uso coletivo, que se enquadram nas regras do Decreto do Estado de São Paulo nº 12342 de 27 de setembro de 1978, por processo de amostragem estratificada foram selecionadas 18 piscinas, que perfazem 64,3% daquelas viáveis para o trabalho, pertencentes a nove localidades ou estabelecimentos. O espaço amostral buscou abranger piscinas de clubes, de instituições de ensino e de academias das classes sociais A, B e C; cobertas e descobertas; infantis e de adultos. / This research work evoluated the sanitary quality of collective use swimming pools in the city of São Carlos, SP. Acoordingly, the pools facilities were investigated in the following subjects: projects, construction, equipments operations, as well as the pools performance inspections themselves. Based on State Legislation and according to the CETESB (Companhia de Tecnologia e Saneamento Ambiental) patterns studies were performed concerning support personel, and the water quality of each stuied unit, in terms of: physical, chemical and bacteriological parameters. From the 28 colectif pools, 18 were selected for this work wich represent 64,3%, and this sampling space, covered club polls, schools and social academies for classes A, B and C, for children and adults.
24

Mickiewicz i naśladowcy studium o zjawisku epigonizmu w systemie literatury romantycznej /

Zielińska, Marta. January 1984 (has links)
"Ksiąźka ta jest poprawioną wersją rozprawy doktorskiej przedstawionej w Instytucie Badań Literackich w 1982 roku." / Includes bibliographical references and index.
25

A guide for planning school and college natatoriums.

Terry, William Lester, January 1955 (has links)
Thesis (Ed.D.)--Teachers College, Columbia University. / Typescript. Sponsor: Harry A. Scott. Dissertation Committee: David B. Austin, Henry H. Linn, . Type C project. Includes bibliographical references (leaves [241]-250).
26

Solar energy for domestic use

Van Zyl, GHC January 2000 (has links)
Thesis (MTech(Chemical engineering))--Cape Technikon, Cape Town, 2000 / The demand for pool heating has increased dramatically over the last few years. This is ascribed to the idea that a swimming pool is expensive and can only be used for four months of the year. Therefore, a need for a relatively inexpensive solar heating system, capable of heating pool water to comfortable temperatures for an extended period, does exist. The least expensive solar heating system for swimming pool heating on the market in South Africa is in the order of R 11000. This is a fixed system, usually mounted on the roof of a house. In order to ensure the safety of minors, a safety net or sail must be installed. This is an additional cost, which approximates R1500, yielding a total cost for safety and heating in the order of R 12500. Copper pipes packed in black material are utilised in these conventional heating systems, and it is the cost of this good heat conductor that makes these units expensive. In this study an alternative pool heating system constructed of PVC was investigated. The system is designed to be flexible, mobile, act as a safety mechanism and absorbs the maximum amount of solar energy available. Dark blue material as opposed to black PVC was selected for aesthetic reasons at the expense of maximum efficiency. The material strength was tested as well as the strength of adhesion. The influence of factors such as exposure to the sun and the effect of water containing chlorine and acid on the material were evaluated. Also, various means of channelling the water through the system for increased efficiency was investigated. A pilot model was constructed and its performance evaluated. It has been concluded that the alternative approach provides effective heating at a lower cost than current systems. Also, the durability of the design was found to be acceptable.
27

Diagnóstico das piscinas de uso coletivo no município de São Carlos - SP / Diagnostic of collective use swimming pools in the city of São Carlos - SP

Denise Conceição de Gois Santos 30 July 2004 (has links)
Este trabalho de pesquisa acadêmica, precipuamente, objetivou avaliar por amostragem, a qualidade sanitária das piscinas de uso coletivo da cidade de São Carlos, SP, com base nas legislações vigentes. O Código Nacional de Saúde, no artigo 44 dá realce ao planejamento, construção e uso das piscinas coletivas sujeitas ao controle das autoridades sanitárias competentes. O Código Sanitário do Estado de São Paulo, no decreto 12.342 de 27 de setembro de 1978, apresenta especificações para as águas de piscina. Para avaliação das instalações anexas foram estudados projetos, construção, operação de equipamentos, manutenção da área construída; foram feitas, também, vistorias das referidas instalações das piscinas propriamente ditas. Com base na legislação estadual e nos padrões da CETESB (Companhia de Tecnologia e Saneamento Ambiental), foram estudados regulamentos quanto a pessoal de apoio; e por meio de parâmetros físicos, químicos e bacteriológicos foi avaliada a qualidade da água de cada unidade amostral do universo de pesquisa deste trabalho porque, em conjunto, os anexos, o tanque de recreação e a água são responsáveis por problemas de saúde pública. Em São Carlos, das 28 piscinas de uso coletivo, que se enquadram nas regras do Decreto do Estado de São Paulo nº 12342 de 27 de setembro de 1978, por processo de amostragem estratificada foram selecionadas 18 piscinas, que perfazem 64,3% daquelas viáveis para o trabalho, pertencentes a nove localidades ou estabelecimentos. O espaço amostral buscou abranger piscinas de clubes, de instituições de ensino e de academias das classes sociais A, B e C; cobertas e descobertas; infantis e de adultos. / This research work evoluated the sanitary quality of collective use swimming pools in the city of São Carlos, SP. Acoordingly, the pools facilities were investigated in the following subjects: projects, construction, equipments operations, as well as the pools performance inspections themselves. Based on State Legislation and according to the CETESB (Companhia de Tecnologia e Saneamento Ambiental) patterns studies were performed concerning support personel, and the water quality of each stuied unit, in terms of: physical, chemical and bacteriological parameters. From the 28 colectif pools, 18 were selected for this work wich represent 64,3%, and this sampling space, covered club polls, schools and social academies for classes A, B and C, for children and adults.
28

Trout Habitat in an Altered Gravel-Bed River with an Augmented Flow Regime

Stout, Jacob B. 01 August 2019 (has links)
The Diamond Fork River, and it’s tributary Sixth Water Creek, has been highly altered in terms of shape, function, and ecologicaly due to large, trans-basin flows additions to the system for irrigation starting in the early 1900s. Flows were exceptionally large for 80 years, after which they were reduced in 2004. Larger than natural flows during the low flow season were then added to the river in an effort to improve ecosystem health and recreational fishing opportunities. Since the prescription additional flow during low flow seasons, the river channel has undergone further change, most noticeably in the form of narrowing. With the channel change that has occurred over the past decade, it has been suggested that the additional flows, which augment baseflows, are too large and that key habitat elements, particularly pools, are lacking throughout the river. We evaluated trout habitat throughout the altered reaches of the Diamond Fork River and Sixth Water Creek which are still subject to flow additions. We used a model to estimate the number of fish a reach can support at a given flow in order to evaluate which flow produces the highest quality trout habitat. We found that the current summer baseflows of 80 cfs for the lower Diamond Fork and 32 cfs for Sixth Water Creek are less than desirable and that flows less than 40 cfs for the lower Diamond Fork and flows between 20 cfs and 30 cfs for Sixth Water Creek would increase the quality of trout habitat. We also evaluated the size and number of pools throughout the system and identified that pools are generally lacking both in size and number relative to standard requirements for trout success. We documented that as the channel narrowed, the number of pools/deep water disappeared. The lack of sediment and the limited number of flows capable of moving sediment were identified as key causes of the channel simplification and loss of pool habitat. Crucial components of future pool formation and maintenance are i) active sediment availability and ii) frequent sediment mobilizing flows. If the baseflow regime were to be lowered, we predict that the channel would narrow, which would increase the effectiveness of floods, increase mobility of sediment, and overall increase pool habitat. This research, as part of a larger, interdisciplinary project, lays the foundation for proposing new flows for the Diamond Fork River that targets ecological goals identified by stakeholders as well as providing information for future habitat restoration projects.
29

MODELING THE RELATIONSHIP BETWEEN COMPETITION AND EFFICIENCY: A CASE STUDY OF THE BITCOIN BLOCKCHAIN

Muslimwal, Shawkatullah 01 December 2022 (has links)
Bitcoin transactions are recorded in a public ledger known as the blockchain. Critical to its security is the distributed system that maintains the blockchain, which is run by individuals known as miners. Bitcoin has a total market capitalization of 273bn US Dollars as of September 2022, and one bitcoin is exchanged at 19,000 US Dollars in the market. Despite its vast market capitalization growth and popularity since its inception, the scalability and efficiency of Bitcoin are still puzzling questions for researchers. This paper used the daily time series data from the inception until September 7, 2022, to analyze the relationship between bitcoin miners' competition and the Bitcoin blockchain's efficiency. The number of daily transactions and average block validation time were used as indicators for the system's efficiency, and the Herfindahl-Hirschman Index (HHI) of miners' hash rate is used as a proxy for mining concentration. Controlling for necessary factors, the econometric analysis in this paper shows that concentration in bitcoin mining is associated with lower system efficiency. Higher competition between miners leads to a higher number of Bitcoin transactions and a lower block validation time.
30

Evaluation of the Conflict Prevention Pools: Sierra Leone

Ginifer, Jeremy, Oliver, K. January 2004 (has links)
yes / P5. The evaluation was undertaken by Bradford University, Channel Research Ltd, the PARC & Associated Consultants. The ACPP Sierra Leone Case study was carried out by Dr Jeremy Ginifer with Ms Kaye Oliver. Work was conducted in three phases. The first was London-based, and involved situating Sierra Leone ACPP activities in the context of UK approaches to conflict prevention and the overall policy framework of the ACPP. The second phase involved field work in Sierra Leone, whilst the third phase involved consultations in London with key government stakeholders. P7. The Sierra Leone Case Study is one of six studies undertaken within the framework of the evaluation of the CPPs. In accordance with the Terms of Reference (ToRs) and the Inception Report, the Evaluation placed maximum emphasis on the macro level: the policy processes in Whitehall by which decisions on allocations are made and implemented by the CPPs. Considerable attention has also been placed on the meso level: the degree to which CPP policies and activities in a given conflict form part of a coherent package of direct interventions by the international community and local actors to the problems of particular large scale deadly conflicts or potential conflicts. The micro-level of analysis (review of specific projects) confines itself largely to the way in which projects impact on the meso and macro levels. The Evaluation has not analysed systematically whether specific projects funded by the CPPs have been well managed and whether they have achieved their specific project goals. Single projects have been analysed to the extent that they reflect on the macro and meso levels. P8. The main findings of the evaluation, reflected in this Synthesis Report, are that the CPPs are doing significant work funding worthwhile activities that make positive contributions to effective conflict prevention, although it is far too early in the day to assess impact. The progress achieved through the CPP mechanisms is significant enough to justify their continuation.

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