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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.
91

Cavity enhanced image recording for holographic data storage

Miller, Bo E., Takashima, Yuzuru 08 September 2016 (has links)
Previously, we proposed and experimentally demonstrated that optical cavities can be employed in recording and readout of plane wave holograms to improve data rates in Holographic Data Storage Systems (HDSS). However, there were some concerns about whether these techniques would be applicable to page based HDSS where signal beams are image bearing and have multiple wave vectors. We have consequently demonstrated cavity enhanced writing of image bearing holograms in Fe: LiNbO3 with a 532 nm wavelength, CW, single mode, DPSS, Nd: YAG, laser with a cavity on the reference arm. The diffraction efficiency was monitored by pseudo-phase-conjugate readout during the recording process. Additionally, standing wave cavity recording was described as inappropriate to HDSS due to introducing additionally gratings to the recording process. The balancing of these grating strengths is analyzed relative to a trade-off in dynamic range consumption vs. data rates and the elimination of the extra gratings via quarter wave plates and isotropic recording media is proposed.
92

Copper-Based N-Heterocyclic Carbene Complexes for Catalytic Enantioselective Conjugate Additions of Alkyl-, Aryl- and Vinyl-Based Nucleophiles to Form All-Carbon Quaternary Stereogenic Centers

May, Tricia Lee January 2011 (has links)
Thesis advisor: Amir H. Hoveyda / Chapter 1 Enantioselective Conjugate Additions of Carbon Nucleophiles to Activated Olefins: Preparation of Enantioenriched Compounds Containing All-Carbon Quaternary Stereogenic Centers. Methods for enantioselective conjugate addition of nucleophiles to activated olefins generating products containing all-carbon quaternary stereogenic centers are critically reviewed. Enantioselective conjugate addition has been shown to be a powerful and concise approach to construct carbon-carbon bonds to prepare compounds containing sterically hindered stereogenic centers and has seen great advances in the past several years. Owing to the difficult nature of additions to relatively unreactive conjugate acceptors, compared to additions generating tertiary stereogenic centers, and construction of a sterically-hindered bond, in many cases, new and active catalysts had to be developed. The review discusses the areas where significant advances have been made as well as current limitations and future outlook. Chapter 2 Development of New and Active Catalysts for Cu-Catalyzed Enantioselective Conjugate Addition of Alkyl- and Arylzinc Reagent. Through development of new chiral catalysts, we have found an active and enantiodiscriminating bidentate, sulfonate-containing NHC-Cu catalyst that effects enantioselective conjugate addition of alkyl- and arylzinc reagents on notoriously difficult trisubstituted cyclic enones. Products are prepared with high levels of selectivity and participate in a variety of further functionalizations. The enantioselective additions are efficient and practical, not requiring rigorously anhydrous or oxygen-free conditions. Chapter 3 Cu-Catalyzed Enantioselective Conjugate Addition of Alkyl- and Arylaluminum Reagents to Trisubstituted Enones. Outlined in this chapter is the first effective solution for Cu-catalyzed enantioselective addition of alkyl and aryl nucleophiles to trisubstituted cyclopentenones generating products bearing a &beta;-all-carbon quaternary stereogenic center. Products are obtained in up to 97% yield and 99:1 er, only requiring 5 mol % of an in situ generated Cu-NHC catalyst. The methodology was highlighted as one of the key steps in the total synthesis of clavirolide C. Not only five-membered rings, but six- and seven-membered rings serve as proficient partners in the enantioselective process. Moreover, in cases for the enantioselective aryl addition, in situ prepared Me<sub>2</sub>AlAr can be used without purification, filtration, or isolation, only requiring the corresponding aryl halides. The additions have also been extended to trisubstituted unsaturated lactones and chromones. Chapter 4 Cu-Catalyzed Enantioselective Conjugate Addition of Vinylaluminum Reagents to Cyclic Trisubstituted Enones. An enantioselective protocol for the formation of &beta;,&beta;-disubstituted cyclic ketones containing a synthetically versatile vinylsilane is disclosed. Enantioselective conjugate addition of in situ prepared silyl-substituted vinylaluminum reagents to &beta;,&beta;-unsaturated ketones promoted by 5 mol % of chiral Cu-NHC complexes delivers desired products with high efficiency (up to 95% yield after purification) and enantioselectivities (up to >98:<2 er). Several functionalizations utilizing the vinylsilanes, vicinal to an all-carbon quaternary stereogenic center, are shown, including an oxidative rearrangement, vinyl iodide formation and protodesilylation, accessing products not previously attainable. Furthermore, the enantioselective protocol is demonstrated as the key transformation in the total synthesis of riccardiphenol B. / Thesis (PhD) — Boston College, 2011. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.
93

Avaliação do impacto da vacina antipneumocócica conjugada na ocorrência de doenças respiratórias em lactentes / Impact assessment of pneumococcal conjugate vaccine on the occurrence of respiratory diseases in infants.

Wanderci Marys Oliveira Abrão 15 December 2014 (has links)
Estudos realizados e recomendados pela OMS e UNICEF, indicam alta prevalência de infecções pneumocócicas e meningocócicas, sobretudo em crianças abaixo dos dois anos de idade. O Streptococcus pneumoniae é um dos agentes mais frequentes de pneumonia, otite média aguda (OMA), meningite e sinusite em crianças. O número global de mortes em crianças menores de cinco anos de idade causadas por pneumonia foi de 8,8 milhões, em 2008. O Ministério da Saúde, devido ao alcance de bons resultados com soroconversão por imunização, indicou a implantação das vacinas antipneumocócica 10-valente e meningocócica C conjugadas no calendário vacinal das crianças menores de dois anos de idade. Na presente pesquisa, conduziu-se um estudo transversal com componente retrospectivo desenvolvido nas redes de Atenção Básica e Hospitalar de Guaranésia, cidade de pequeno porte do interior do estado de Minas Gerais. Objetivou-se avaliar o impacto da vacinação na ocorrência de doenças respiratórias em lactentes, considerando o período anterior e posterior à introdução da vacina antipneumocócica 10-valente, no Programa Nacional de Imunização. Na análise estatística definiu-se o período entre 2009 e 2012. O método de estudo adotado foi o um estudo transversal aninhado em uma série temporal, sendo observado que no período pós introdução da vacina antipneumocócica 10 valente conjugada houve uma redução de 40% na prevalência de pneumonia adquirida na comunidade, com diferença estatística entre os dois períodos . Confirmou-se que a oscilação sazonal tem interferência nas doenças estudadas. Em relação ao sexo, constatou-se que o masculino tem predomínio sobre o feminino quanto ao acometimento por pneumonia. Foi observado que o sexo masculino apresentou 28% mais chance de PNM. Em relação à otite média aguda e à rinossinusite, a variável sexo não apresentou predomínio entre elas. Os dados estatísticos, considerando a razão de prevalência (RP = 1,96 (IC95%: 1,52 2,53); p <0,05), sugeriram que não vacinar está associado com a ocorrência de PNM. Constatou-se que a prevalência de PNM foi 70% menor (RP 0,30 (IC95%: 0,24 0,37); p<0,05) nas crianças com vacina em dia comparando-se àquelas com a vacina em atraso, ou seja, manter vacina em dia sugere proteção contra PNM. No entanto, houve 53% menos OMA entre não vacinados do que entre vacinados (RP = 0,47 (IC95%: 0,35 0,64); p<0,05). Diante dos resultados encontrados, pode-se concluir que a vacinação antipneumocócica 10-valente está associada com redução dos casos de pneumonia adquirida na comunidade em lactentes. / Studies and recommended by WHO and UNICEF, indicate a high prevalence of pneumococcal and meningococcal infections, especially in children under two years of age. Streptococcus pneumoniae is one of the most frequent agents of pneumonia, acute otitis media (AOM), meningitis and sinusitis in children. The overall number of deaths in children under five years of age caused by pneumonia was 8.8 million in 2008. The Ministry of Health due to reach good results with seroconversion by immunization, indicated the implementation of pneumococcal vaccines 10- meningococcal C conjugate and brave in the immunization schedule of children under two years of age. In this research, conducted a cross-sectional study with retrospective component developed in primary care networks and Hospital Guaranésia, small town in the state of Minas Gerais. This study aimed to assess the impact of vaccination on the incidence of respiratory diseases in infants, considering the time before and after the introduction of the vaccine pneumococcal 10-valent, the National Immunization Program. Statistical analysis defined the period between 2009 and 2012. The adopted method of study was a cross-sectional study nested in a time series, it was observed that in the post introduction period of pneumococcal vaccine conjugate 10 brave there was a 40% reduction in the prevalence of community-acquired pneumonia, with statistical difference between the two periods. It was confirmed that the seasonal oscillation has interference in the diseases. With regard to gender, it was found that the male is predominant over females in relation to involvement by pneumonia. It was observed that men had 28% more chance of pneumonia. In relation to acute otitis media and sinusitis, sex does not showed a predominance among them. Statistical data, considering the prevalence ratio (PR = 1.96 (95% CI: 1.52 to 2.53), p <0.05), suggested that not vaccinating is associated with the occurrence of pneumonia. It was found that the prevalence of pneumonia was 70% lower (PR 0.30 (95% CI: 0.24 to 0.37), p <0.05) in children with day vaccine is compared to those of the vaccine in delay, ie to keep day suggests vaccine protection against pneumonia. However, there were 53% fewer of AOM than for unvaccinated vaccinated (OR = 0.47 (95% CI: 0.35 to 0.64); p <0.05). Considering the results, it can be concluded that vaccination pneumococcal 10-valent is associated with reduction of cases of community-acquired pneumonia in infants.
94

Some fast algorithms in signal and image processing.

January 1995 (has links)
Kwok-po Ng. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 138-139). / Abstracts / Summary / Introduction --- p.1 / Summary of the papers A-F --- p.2 / Paper A --- p.15 / Paper B --- p.36 / Paper C --- p.63 / Paper D --- p.87 / Paper E --- p.109 / Paper F --- p.122
95

[en] WATER AND OIL FLOW SIMULATION IN POROUS MEDIA / [pt] SIMULAÇÃO DO ESCOAMENTO DE ÁGUA E ÓLEO EM MEIOS POROSOS

MARCOS AURELIO CITELI DA SILVA 14 April 2004 (has links)
[pt] Muitos problemas provenientes do mundo real podem ser modelados por sistemas de equações diferenciais parciais (EDP´s). No entanto, as equações resultantes da discretização produzem matrizes grandes e freqüentementes mal condicionadas. Este trabaho implementa o método de elementos finitos mistos para resolver numericamente um sistema de EDP´s oriundo de um modelo de escoamento de fluidos em meios porosos e melhora sua performance usando precondicionadores e processamento paralelo. / [en] Many problems arising from real world can be represented by systems of partial diferential equations (PDE´s). However, the resulting discrete equations produce large and frequently bad conditioned matrices. This work implements the mixed finite element method to numerically solve a system of PDE´s coming from a multiphase flow in porous media model and improve its performance by preconditioners and parallel processing.
96

Model-independent arbitrage bounds on American put options

Höggerl, Christoph January 2015 (has links)
The standard approach to pricing financial derivatives is to determine the discounted, risk-neutral expected payoff under a model. This model-based approach leaves us prone to model risk, as no model can fully capture the complex behaviour of asset prices in the real world. Alternatively, we could use the prices of some liquidly traded options to deduce no-arbitrage conditions on the contingent claim in question. Since the reference prices are taken from the market, we are not required to postulate a model and thus the conditions found have to hold under any model. In this thesis we are interested in the pricing of American put options using the latter approach. To this end, we will assume that European options on the same underlying and with the same maturity are liquidly traded in the market. We can then use the market information incorporated into these prices to derive a set of no-arbitrage conditions that are valid under any model. Furthermore, we will show that in a market trading only finitely many American and co-terminal European options it is always possible to decide whether the prices are consistent with a model or there has to exist arbitrage in the market.
97

Cost-effectiveness analysis of 10- and 13-valent pneumococcal conjugate vaccines in Peru

Mezones Holguín, Edward, Canelo Aybara, Carlos, David Clark, Andrew, Bess Janusz, Cara, Jaúregui, Bárbara, Escobedo Palza, Seimer, Hernandez, Adrian V., Berhane, Yemane, Vega Porras, Denhiking, González, Marco, Fiestas, Fabián, Toledo , Washington, Michele, Fabiana, Suárez, Víctor J. 24 November 2015 (has links)
Objective To evaluate the cost-effectiveness of introducing the 10-valent pneumococcal conjugate vaccine (PCV10) versus the 13-valent PCV (PCV13) to the National Immunization Schedule in Peru for prevention of pneumococcal disease (PD) in children <5 years of age. Methods The integrated TRIVAC vaccine cost-effectiveness model from the Pan American Health Organization's ProVac Initiative (version 2.0) was applied from the perspective of the Government of Peru. Twenty successive cohorts of children from birth to 5 years were evaluated. Clinical outcomes were pneumococcal pneumonia (PP), pneumococcal meningitis (PM), pneumococcal sepsis (PS) and acute otitis media from any causes (AOM). Measures included prevention of cases, neurological sequelae (NS), auditory sequelae (AS), deaths and disability adjusted life years (DALYs). A sensitivity analyses was also performed. Findings For the 20 cohorts, net costs with PCV10 and PCV13 were US$ 363.26 million and US$ 408.26 million, respectively. PCV10 prevented 570,273 AOM; 79,937 PP; 2217 PM; 3049 PS; 282 NS; 173 AS; and 7512 deaths. PCV13 prevented 419,815 AOM; 112,331 PN; 3116 PM; 4285 PS; 404 NS; 248 AS; and 10,386 deaths. Avoided DALYs were 226,370 with PCV10 and 313,119 with PCV13. Saved treatment costs were US$ 37.39 million with PCV10 and US$ 47.22 million with PCV13. Costs per DALY averted were US$ 1605 for PCV10, and US$ 1304 for PCV13. Sensitivity analyses showed similar results. PCV13 has an extended dominance over PCV10. Conclusion Both pneumococcal vaccines are cost effective in the Peruvian context. Although the net cost of vaccination with PCV10 is lower, PCV13 prevented more deaths, pneumococcal complications and sequelae. Costs per each prevented DALY were lower with PCV13. Thus, PCV13 would be the preferred policy; PCV10 would also be reasonable (and cost-saving relative to the status quo) if for some reason 13-valent were not feasible. / This study was presented at 9th International Symposium of Pneumococci and Pneumococcal Diseases, Hyderabad, India, March 2014, and supported by the National Council of Science, Technology and Technological Innovation of Peru (CONCYTEC) and International Clinical Epidemiology Network (INCLEN Trust) / This study was made possible through the financial support of the Instituto Nacional de Salud (National Institute of Health, Lima, Peru) and the PROVAC Initiative of the Pan American Health Organization (Washington, DC, USA).
98

Desenvolvimento de processo para obtenção do método de conjugação do polissacarídeo capsular de Haemophilus influenzae tipo b com toxóide tetânico. / Development of process for the conjugation of capsular polysaccharide Haemophilus influenzae type b with tetanus toxoid.

Lorthiois, Ana Paula de Almeida Aranha 18 February 2008 (has links)
Haemophilus influenzae type b (Hib) é uma importante bactéria Gram-negativa causadora de pneumonia, meningite e septicemia em crianças abaixo dos 5 anos de idade. A prevenção contra a doença pode ser alcançada pela imunização da população com vacina conjugada polissacarídeo-proteína, uma vez que a vacina de polissacarídeo não é eficiente. As vacinas conjugadas disponíveis comercialmente custam para o governo brasileiro cerca de US2,7 a dose, sendo necessárias no mínimo 3 doses para imunização completa. O presente estudo desenvolveu um novo método de conjugação de polissacarídeo capsular de Hib (PRP) com toxóide tetânico (TT). O método hidrazona baseia-se em 3 etapas simples: oxidação e derivatização de PRP com espaçador molecular e conjugação com TT na presença de uma carbodiimida e de um éster amino reativo. Após um estudo detalhado de cada etapa do método hidrazona, o novo processo mostrou excelentes resultados de rendimento mesmo após escalonamento. A imunogenicidade e o índice de avidez do conjugado hidrazona foram avaliados e os resultados encontrados foram comparáveis a vacina comercial Hiberix®. A técnica de HPSEC mostrou-se eficaz e o perfil cromatográfico do conjugado hidrazona foi muito similar ao da vacina Hiberix. Finalmente, o novo processo de conjugação de vacina permitiu o desenvolvimento de uma poderosa tecnologia constituindo uma excelente opção para o governo brasileiro. / Haemophilus influenzae type b (Hib) is an important encapsulated bacteria, which causes pneumonia, meningitis and septicaemia in infants. Prevention against infection is achieved by the currently available polysaccharide protein conjugate vaccine. However, due to its high production costs (around U$ 2,7 per dose) this formulation cannot be used in mass immunization programs in Brazil. In the present study, we developed a new method for the conjugation of Hib polysaccharide (PRP) and tetanus toxoid (TT). The hydrazone method is based on 3 singles steps: PRP oxidation, PRP derivatization with linker spacer and conjugation with TT in the presence of carbodiimide and an amino reactive ester. After detailed study of each step of method, the new process showed very good yield of conjugation even when it was scaled-up. The immunogenicity and the avidity index of hydrazone conjugate were evaluated and the results were comparable with those obtained with the commercial vaccine Hiberix®. The HPLC hydrazone profile was very similar to HPLC Hiberix profile. Finally, the new conjugation process allows the development of a powerful vaccine technology, constituting an excellent choice for the brazilian government.
99

Investigation of a complex conjugate matching circuit for a piezoelectric energy harvester

Ku Ahamad, Ku Nurul Edhura January 2018 (has links)
The work described in this thesis is aimed at developing a novel piezoelectric cantilever energy harvesting circuit, so that more energy can be obtained from a particular piezoelectric harvester than is possible using conventional circuits. The main focus of the work was to design, build and test a proof of principle system, and not a commercial version, so as to determine any limitations to the circuit. The circuit functions by cancelling the capacitive output reactance of the piezoelectric harvester with a simulated inductance, and is based on an idea proposed by Qi in 2011. Although Qi's approach demonstrated that the circuit could function, the system proved too lossy, and so a less lossy version is attempted here. Experimental and software simulations are provided to verify the theoretical predictions. A prototype amplified inductor circuit was simulated and tested. From the simulation results, although harmonic current losses were found in the circuit, it was found that the circuit should produce an amplified effective inductance and a maximum output power of 165mW. The effective inductance is derived from the voltage across the 2H inductor, and this voltage is amplified and applied to the circuit via an inverter, to provide an extra simulated inductance, so that the overall inductance can be resonated with the piezoelectric harvester output capacitance. Hence the capacitive impedance of the harvester is nearly cancelled. The study and analysis of the amplified inductor circuit was carried out for a single cantilever harvester. Both open loop and closed loop testing of the system were carried out. The open loop test showed that the concept should function as predicted. The purpose of the closed loop test was to make the system automatically adjust for different resonance frequencies. The circuit was tested at 52Vpp inverter output voltage, and demonstrated a harvested power of 145.5mW. Experimental results show that the harvester output power is boosted from 8.8mW as per the manufacturer data sheet to 145.5mW (16.5 times). This is approximately double the power available using circuits described in the literature.
100

Image reconstruction with multisensors.

January 1998 (has links)
by Wun-Cheung Tang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references. / Abstract also in Chinese. / Abstracts --- p.1 / Introduction --- p.3 / Toeplitz and Circulant Matrices --- p.3 / Conjugate Gradient Method --- p.6 / Cosine Transform Preconditioner --- p.7 / Regularization --- p.10 / Summary --- p.13 / Paper A --- p.19 / Paper B --- p.36

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