• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 129
  • 28
  • 26
  • 19
  • 8
  • 5
  • 4
  • 3
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 293
  • 42
  • 37
  • 31
  • 30
  • 29
  • 27
  • 27
  • 25
  • 23
  • 21
  • 19
  • 19
  • 17
  • 16
  • 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.
71

Creating Recommendations for Long Acting Reversible Contraceptive Use for Adolescents

Strawn, Katie, Strawn, Katie January 2017 (has links)
The purpose of this research project is to develop a clinical practice guideline for contraceptive counseling to include long acting reversible contraceptive (LARC) recommendations for the adolescent population. LARCs, which include intrauterine devices and implants, are the top-tier contraceptive for nulliparous women yet they are only used in less than 6% of women under 19 years old. There is no LARC clinical practice guideline that addresses the adolescent’s unique developmental and psychosocial needs that arise. A clinical practice guideline with adolescent-specific recommendations will strengthen counseling especially for long-acting reversible contraceptives. The review of literature searched PubMed, CINHAL, National Guideline Clearinghouse, Google Scholar and the Cochrane Library using search terms "LARCs," and "contraceptive counseling." The search yielded over 35,000 results; titles and abstracts were reviewed using pre-determined inclusion and exclusion criteria. The final source documents included forty-eight applicable manuscripts, which were graded using the United States Preventative Task Force (USPSTF) scale. The evidence was then sorted by similar findings and practice recommendations. The findings were used to formulate practice statements, which were then input into the Bridge-wiz software. The program generated recommendations and assigned a strength rating, and the clinical practice guideline was written from these recommendations. Finally, four clinical experts were identified using snowball sampling; they each participated in the final appraisal using the AGREE II tool. Based on the analysis of the review of literature, fifteen evidenced-based recommendations emerged. The recommendation topics included: best-practices for recommending LARCs, using developmentally appropriate teaching, providing youth-friendly services, and eliminating potential barriers to LARC uptake in adolescents. There are fifteen practice recommendations that increase adolescent uptake of LARCs. Limitations for the project included the absence of an internal review committee to grade the evidence and assign a strength to each recommendation. The use of Bridge-wiz software and the USPSTF evidence scale minimized bias. Providers can facilitate use of LARCs among adolescents by using developmentally appropriate and comprehensive contraceptive counseling. If more adolescents chose a LARC as their primary form of contraception, then overall teenage pregnancies may decrease. Further research is needed to understand other barriers and possible interventions.
72

The Use of Reversible Covalent Bonding and Induced Intramolecularity to Achieve Selectivity and Rate Acceleration in Organic Reactions

Worthy, Amanda D. January 2013 (has links)
Thesis advisor: Kian L. Tan / Chapter 1. Catalytic directing group, I, which was designed with the ability to form a reversible covalent bond with a substrate and bind a metal, was shown to direct the hydroformylation of allylic amines. The efficient regioselective hydroformylation of a variety of 1,2-disubstituted allylic sulfonamides to form β-amino-aldehydes under mild conditions has been shown. Chapter 2. Building off of the successful application of I, enantioenriched catalytic directing group, II, was designed and synthesized. It retained the essential features to direct hydroformylation to obtain good regioselectivity while also providing a chiral environment to induce absolute stereocontrol. Under mild conditions, a variety of disubstituted olefins react to give good yields and excellent enantioselectivites. Thus, the first enantioselective reaction performed with a catalytic directing group was demonstrated. Chapter 3. A new set of organocatalysts was developed that benefits from reversible covalent bonding and induced intramolecularity. The desymmetrization of meso-1,2-diols was accomplished using organocatalyst III, which was synthesized easily and cheaply. Experimental results indicate that the selectivity and increased reactivity are a result of the ability of III to pre-organize the substrate through a reversible, covalent bond. A variety of cyclic and acylic substrates were shown to react efficiently with good enantioselectivities under mild conditions. The catalyst's ability to functionalize cis-1,2-diols selectively indicated it might be successfully applied to site selective catalysis. Thus, the selective functionalization of a secondary alcohol in the presence of a primary alcohol was developed using a combination of binding selectivity and stereoselectivity. The (S)-enantiomer forms the secondary functionalized product while the (R)-enantiomer forms the primary functionalized product with high selectivity. As the enantiomers preferentially form different functionalized products, a regiodivergent reaction on a racemic mixture resulted giving two valuable enriched products. / Thesis (PhD) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.
73

Strategies for preventing unintended pregnancy

Michie, Lucy Helen January 2016 (has links)
In the United Kingdom (UK) there is easy access to a wide range of contraceptive methods, available at no cost. In addition, oral emergency contraception (EC) (1.5 mg levonorgestrel) is now widely available from the community pharmacy. In spite of this, unintended pregnancy is common. In 2014 in England and Wales, 184,571 induced abortions were performed, and in Scotland, the corresponding figure was 11,475. Long acting reversible methods such as contraceptive implants and intrauterine contraception, are amongst the most effective methods available and National Institute for Health and Care Excellence (NICE) recommends that increased uptake can lead to fewer unintended pregnancies. However, uptake of long acting reversible contraceptive (LARC) methods remains low. The majority of women who require to use EC do so following unprotected sex or an accident with a condom. Increasingly women in Great Britain prefer to attend a pharmacy for EC rather than a sexual and reproductive health (SRH) service or general practitioner (GP). Starting an effective on-going method of contraception after EC use is clearly important if women are to avoid unintended pregnancy. Community pharmacists in the UK and most other high income countries are usually unable to provide any on-going contraception except condoms. So we have created a situation where EC is provided almost solely from settings where other more effective methods of contraception cannot be immediately provided. Novel strategies are therefore required to facilitate both uptake and continuation of the most effective methods of contraception, in order to prevent unintended pregnancy for more women. This thesis presents a mixture of biomedical, clinical and health services research to evaluate a series of strategies aimed at improving uptake of the most effective methods of contraception. Two studies investigated patient knowledge and information provision relating to contraceptive methods. The first sought to determine if women held misconceptions about intrauterine methods of contraception, and revealed that although myths persist in a small number of women, a lack of knowledge about these methods was also evident. The second study aimed to determine if the use of a digital video disc (DVD) to provide contraceptive information was acceptable and informative to women, and identified that it is, and could possibly enhance patient consultations. Studies three, four and five investigated strategies aimed at increasing the uptake of effective on-going contraception, following emergency contraception provided from a community pharmacy, and patient and health care provider attitudes to such approaches. They showed that simple interventions such as supplying one month of a progestogen only pill (POP), or offering rapid access to a family planning clinic (FPC), hold promise as strategies to increase the uptake of effective contraception after EC and that both women and clinicians were positive about such measures. Additionally, the problems encountered in conducting these studies provided valuable feedback to inform further development of research methods in the community pharmacy setting, and larger scale studies of such interventions. Community SRH services may be well placed to deliver more abortion care in the UK, and consequently this may result in greater uptake of contraception post abortion. Study six aimed to determine the views of health professionals working in SRH regarding their attitudes towards providing more abortion services and also the views of staff within one community SRH centre in Scotland where a service providing early medical abortion was due to commence. It showed there is clear support amongst health professionals in community SRH in the UK towards greater participation in provision of abortion care services.
74

Modelo oculto de Markov para imputação de genótipos de marcadores moleculares: Uma aplicação no mapeamento de QTL utilizando a abordagem bayesiana / Hidden Markov model for imputation of genotypes of molecular markers: An application in QTL mapping using Bayesian approach

Medeiros, Elias Silva de 28 August 2014 (has links)
Muitas são as características quantitativas que são, significativamente, influenciadas por fatores genéticos, em geral, existem vários genes que colaboram para a variação de uma ou mais características quantitativas. As informações ausentes a respeito dos genótipos nos marcadores moleculares é um problema comum em estudo de mapeamento genético e, por conseguinte, no mapeamento dos locus que controlam estas características fenotípicas (QTL). Os dados que não foram observados ocorrem, principalmente, devido a erros de genotipagem e de marcadores não informativos. Para solucionar este problema foi utilizado o método do modelo oculto de Markov para inferir estes dados. Os métodos de acurácias evidenciaram o sucesso da aplicação desta técnica de imputa- ção. Uma vez imputado, na inferência bayesiana estes dados não serão mais tratados como uma variável aleatória resultando assim, numa redução no espaço paramétrico do modelo. Outra grande dificuldade no mapeamento de QTL se deve ao fato de que não se conhece ao certo a quantidade destes que influenciam uma dada característica, fazendo com que surjam diversos problemas, um deles é a dimensão do espaço paramétrico e, consequentemente, a obtenção da amostra a posteriori. Assim, com o objetivo de contornar este problema foi proposta a utilização do método Monte Carlo via cadeia de Markov com Saltos Reversíveis, uma vez que este permite flutuar, entre cada iteração, modelos com diferentes quantidades de parâmetros. A utilização da abordagem bayesiana permitiu detectar cinco QTL para a característica estudada. Todas as análises foram implementadas no programa estatístico R. / There are many quantitative characteristics which are significantly influenced by genetic factors, in general, there are several genes that contribute to the variation of one or more quantitative trait. The missing information about the genotypes in molecular markers is a common problem in studying genetic mapping and therefore the mapping of loci that control these phenotypic traits (QTL). The data were not observed occur mainly due to errors in genotyping and uninformative markers. To solve this problem the method of occult Markov model to infer this information was used. Techniques accuracies demonstrated the successful application of this technique of imputation. Once allocated, in the Bayesian inference this data will no longer be treated as a random variable thus resulting in a reduction in the parameter space of the model. Another great difficulty in mapping QTL is due to the fact that no one knows exactly the amount of these which influence a given characteristic, so that several problems arise, one of them is dimension of the parameter space and, consequently, obtaining the sample a posterior. Thus, in order to solve this problem using the method via Monte Carlo Markov chain Reversible Jump was proposed, since this allows fluctuate between each iteration, models with different numbers of parameters. The use of the Bayesian approach allowed five QTL detected for the studied trait. All analyzes were implemented in the statistical software R.
75

Wildlife population control comprehensive and critical literature review on contraceptive methods in wildlife - mammals / Controle das populações de animais silvestres revisão bibliográfica compreensiva e crítica sobre os métodos de contracepção em animais silvestres - mamíferos

Rosenfield, Derek Andrew 29 March 2016 (has links)
This systematic review consolidates and discusses all the advantages and disadvantages of each contraceptive method, organized by mammalian species, with emphasis on reversible immune-contraception, obtained from the international scientific literature. The objective is to deepen the knowledge and elucidate adequate solutions to a serious global problem of wildlife population control. Furthermore, serving as pre-project to the next stage of development of a contraceptive method, economically viable, with better attributes, high effectiveness of the action, better and safer techniques of application, and more importantly, ensure overall health and population genetics. Finalizing this review by offering in a brief and concise manner, an updated understanding of reversible contraceptive methods, organized by methods, taxon, drugs, and associated risks / Esta revisão sistemática, consolida e discuti todas as vantagens e desvantagens de cada método contraceptivo, organizada por espécies de mamíferos, com ênfase em imunocontracepção reversível, obtidos em literatura científica internacional. O objetivo é aprofundar os conhecimentos e elucidar soluções adequadas para o grande problema mundial do controle das populações de animais silvestres. Além disto, pode servir como pré-projeto para a próxima fase de desenvolvimento de um método contraceptivo economicamente viável, com melhores atributos, alta eficácia da ação, técnicas de aplicação melhores e mais seguras, e mais importante, garantir saúde geral e genética das populações. Finalizando, esta revisão oferecer de forma breve e concisa, uma atualização sobre o conhecimento de métodos contraceptivos reversíveis, organizada por métodos, táxon, fármacos, e riscos associados
76

Bayesian surface smoothing under anisotropy

Chakravarty, Subhashish 01 January 2007 (has links)
Bayesian surface smoothing using splines usually proceeds by choosing the smoothness parameter through the use of data driven methods like generalized cross validation. In this methodology, knots of the splines are assumed to lie at the data locations. When anisotropy is present in the data, modeling is done via parametric functions. In the present thesis, we have proposed a non-parametric approach to Bayesian surface smoothing in the presence of anisotropy. We use eigenfunctions generated by thin-plate splines as our basis functions. Using eigenfunctions does away with having to place knots arbitrarily, as is done customarily. The smoothing parameter, the anisotropy matrix, and other parameters are simultaneously updated by a Reversible Jump Markov Chain Monte Carlo (RJMCMC) sampler. Unique in our implementation is model selection, which is again done concurrently with the parameter updates. Since the posterior distribution of the coefficients of the basis functions for any given model order is available in closed form, we are able to simplify the sampling algorithm in the model selection step. This also helps us in isolating the parameters which influence the model selection step. We investigate the relationship between the number of basis functions used in the model and the smoothness parameter and find that there is a delicate balance which exists between the two. Higher values of the smoothness parameter correspond to more number of basis functions being selected. Use of a non-parametric approach to Bayesian surface smoothing provides for more modeling flexibility. We are not constrained by the shape defined by a parametric shape of the covariance as used by earlier methods. A Bayesian approach also allows us to include the results obtained from previous analysis of the same data, if any, as prior information. It also allows us to evaluate pointwise estimates of variability of the fitted surface. We believe that our research also poses many questions for future research.
77

Methodology for mapping quantum and reversible circuits to IBM Q architectures /

Almeida, Alexandre Araujo Amaral de. January 2019 (has links)
Orientador: Alexandre César Rodrigues da Silva / Abstract: Research in the field of quantum circuits has increased as technology advances in the development of quantum computers. IBM offers access to quantum computers via the cloud service called IBM Q. However, these architectures have some restrictions regarding the types of quantum gates that can be realized. This work proposes a methodology for the mapping of quantum and reversible circuits to the architectures made available by the IBM Q project. The methodology consists in finding CNOT mappings using a set of defined qubits movements to satisfy the architectures constraints by adding as few gates as possible. In order to reduce the number of CNOT gates needing mapping, the permutation of the circuit can be changed. One alternative to find this permutation is trough exhaustive search. However, is not feasible as the number of qubit increases. To solve this problem, the permutation problem was formulated as an Integer Linear Programming problem. The mapping of quantum circuits realized with non-implementable gates and reversible Toffoli circuits to the IBM quantum architectures were proposed in this work as well. This was done by adapting the developed CNOT mappings along with the Integer Linear Programming formulation. The proposed methodology was evaluated by mapping quantum and reversible circuits to an IBM quantum architectures with 5 and 16 qubits. The results were compared with two algorithms that map quantum circuits to IBM architectures. The cost metric used in the evalua... (Complete abstract click electronic access below) / Resumo: Pesquisa no campo de circuitos quânticos tem alavancado conforme a tecnologia avança no desenvolvimento de computadores quânticos. Atualmente, a IBM oferece acesso a computadores quânticos através do serviço em nuvem chamado IBM Q. No entanto, essas arquiteturas têm algumas restrições com relação aos tipos de portas quânticas e qubits em que uma porta CNOT pode ser implementada. Neste trabalho foi proposta uma metodologia para o mapeamento de circuitos quânticos e reversíveis para as arquiteturas disponibilizadas pelo projeto IBM Q. A metodologia consiste em mapear as portas CNOT utilizando uma série de movimentos de qubits, mantendo a permutação do circuito inalterada. A fim de reduzir o número de portas CNOT não implementáveis, a permutação do circuito pode ser alterada. Uma alternativa para encontrar essa permutação é a busca exaustiva. No entanto, é inviável conforme o número de qubits aumenta. Para resolver este problema, o problema de permutação foi formulado como um problema de Programação Linear Inteira. Como a metodologia é facilmente adaptável, o mapeamento de circuitos quânticos utilizando portas quânticas não implementáveis e circuitos reversíveis Toffoli também foram propostas neste trabalho. A avaliação da metodologia proposta foi feita com a realização do mapeamento de circuitos quânticos e reversíveis para arquiteturas quânticas com 5 e 16 qubits. Os resultados foram comparados com dois algoritmos que mapeiam circuitos quânticos para arquiteturas IBM. A métric... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor
78

Bayesian wavelet approaches for parameter estimation and change point detection in long memory processes

Ko, Kyungduk 01 November 2005 (has links)
The main goal of this research is to estimate the model parameters and to detect multiple change points in the long memory parameter of Gaussian ARFIMA(p, d, q) processes. Our approach is Bayesian and inference is done on wavelet domain. Long memory processes have been widely used in many scientific fields such as economics, finance and computer science. Wavelets have a strong connection with these processes. The ability of wavelets to simultaneously localize a process in time and scale domain results in representing many dense variance-covariance matrices of the process in a sparse form. A wavelet-based Bayesian estimation procedure for the parameters of Gaussian ARFIMA(p, d, q) process is proposed. This entails calculating the exact variance-covariance matrix of given ARFIMA(p, d, q) process and transforming them into wavelet domains using two dimensional discrete wavelet transform (DWT2). Metropolis algorithm is used for sampling the model parameters from the posterior distributions. Simulations with different values of the parameters and of the sample size are performed. A real data application to the U.S. GNP data is also reported. Detection and estimation of multiple change points in the long memory parameter is also investigated. The reversible jump MCMC is used for posterior inference. Performances are evaluated on simulated data and on the Nile River dataset.
79

Infinite system of Brownian balls : equilibrium measures are canonical Gibbs

Roelly, Sylvie, Fradon, Myriam January 2006 (has links)
We consider a system of infinitely many hard balls in R<sup>d</sup> undergoing Brownian motions and submitted to a smooth pair potential. It is modelized by an infinite-dimensional stochastic differential equation with a local time term. We prove that the set of all equilibrium measures, solution of a detailed balance equation, coincides with the set of canonical Gibbs measures associated to the hard core potential added to the smooth interaction potential.
80

Infinite system of Brownian balls with interaction : the non-reversible case

Fradon, Myriam, Roelly, Sylvie January 2005 (has links)
We consider an infinite system of hard balls in Rd undergoing Brownian motions and submitted to a smooth pair potential. It is modelized by an infinite- dimensional Stochastic Differential Equation with an infinite-dimensional local time term. Existence and uniqueness of a strong solution is proven for such an equation with fixed deterministic initial condition. We also show that Gibbs measures are reversible measures.

Page generated in 0.2653 seconds