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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.
271

Investment Analysis: Evaluating the Loss and Risk of a Stocks and Options Portfolio

Infantino, Shanna 02 May 2012 (has links)
With the ripples in the financial markets and economic stresses that occur around the world today, it would be beneficial to have some insight into the tools that help investors learn about the riskiness of their portfolios. At what value is one's portfolio in danger of being completely wiped out? We aim to further the understanding of values such as these and give an assessment of some risk measures by investing in an interactive portfolio, as well as estimating the values at risk and expected shortfalls of this portfolio.
272

Investment Analysis: Evaluating the Loss and Risk of a Stocks and Options Portfolio

Shah, Azuri 02 May 2012 (has links)
With the ripples in the financial markets and economic stresses that occur around the world today, it would be beneficial to have some insight into the tools that help investors learn about the riskiness of their portfolios. At what value is one's portfolio in danger of being completely wiped out? We aim to further the understanding of values such as these and give an assessment of some risk measures by investing in an interactive portfolio, as well as estimating the values at risk and expected shortfalls of this portfolio.
273

Auditory brainstem response findings in a group of neurologically compromised children: a retrospective study

Baillieu, Karen Mary 11 September 2014 (has links)
There is a higher prevalence of hearing loss in children with diagnosed neurological disorders than the general paediatric population. It is therefore essential that these children have their hearing assessed. Conventional behavioural audiometry requires participation from the child, and in a majority of this population with neurological pathology this is not always possible owing to their neurocompromised state. These children will have to undergo objective testing, such as the Auditory Brainstem Response (ABR) in order to obtain estimated hearing thresholds, as this requires no active involvement from the patient. This study therefore aims to describe the audiological ABR findings in order to determine hearing function in this group and to establish a relationship between audiological ABR findings to behavioural audiometry findings where these exist in a group of neurologically disordered children in a tertiary hospital in South Africa. Methods: A retrospective review was conducted on 40 ABR patient records of children between the ages of 5 months and 10 years diagnosed with a neurological disorder. Behavioural audiometry results were then sought for these children, where these existed. Hearing status was described for each child per ear for both objective and behavioural results, and descriptive statistics were conducted. Results: 56.25 % (n=45) of ears in this study presented with normal hearing on ABR testing. No behavioural audiometry results were obtained in 72.5 % (n=58) of ears in this study. Results correlated between ABR and behavioural testing for only 7.5% (n=8) of ears tested and in all eight of these ears the hearing result was within normal hearing limits. Twelve and a half percent (n=10) of ears were misdiagnosed on behavioural testing. More premature infants were able to be tested behaviourally when compared to other pathologies. Cerebral palsy, Down’s Syndrome, prematurity and RVD were the pathologies in which the most hearing losses were diagnosed. Conclusions: Behavioural audiometry appears a largely unreliable method of hearing testing in children diagnosed with neurological disorders as results were obtained in only 27.5 % of the study sample; however it remains the gold standard in paediatric hearing testing in order to evaluate the entire auditory system and provides information on how a child processes sound, unlike ABR testing which only provides hearing information up to the auditory brainstem. This study highlights the high prevalence of hearing problems in children with neurological disorders and therefore the importance of hearing testing in this population. Hearing thresholds should be established for subsequent remediation via objective testing. Conditioning should continue simultaneously for a behavioural audiological test battery with adaptations for the child’s developmental ability.
274

Noise-induced hearing loss in a paper mill in KZN, South Africa

Viljoen, Christina Adriana 17 July 2008 (has links)
ABSTRACT It is well documented that repetitive exposures to high intensity sound can cause acoustic trauma to the ear resulting in hearing loss, and that occupational noise is a significant cause of adult-onset hearing loss. Research world wide has indicated a significant number of workers with hearing loss attributed to noise exposure. Noise-Induced Hearing Loss (NIHL) claims are responsible for the majority of occupational disease payouts. The study was undertaken in order to determine the extent of hearing loss due to noise exposure that could be ascribed to excessive exposure to noise, and to describe the noise-induced hearing loss by severity, type of work, and area of work and duration of service. The cross-sectional study included 466 workers employed in a pulp and paper mill in KwaZulu Natal (KZN) South Africa. It involved the assessment of 932 individual audiograms to diagnose noise-induced hearing loss and the calculation of the percentage loss of hearing from pre placement to the year 2005. Audiometry results were presented for noise-induced hearing loss in relation to area of work, duration of service, categories of severity and age group. The prevalence of noise-induced hearing loss in the pulp and paper mill was 21% (98/466) and with 79% (368/466) of workers whose audiograms returned results not indicating NIHL. 75 workers were excluded due to workplace transfers. Type of work, area of work and years of service correlated significantly with a diagnosis of noise-induced hearing loss. As a department, the wood yard (which included the wood chipping facility, maintenance workers and workers with 10 – 20 years of service) showed the most significant association. In categories of severity 16.7% of workers suffering from NIHL fall in the ≤ 5 Percentage Loss of Hearing PLH category. This study has confirmed the findings of others that noise exposure is a significant hazard in industry and an effective noise control programme is the only way to reduce the risk of NIHL. _____________________________________________________________________
275

The mechanisms of continuous tooth replacement in the Nile crocodile (Crocodylus niloticus)

Thomadakis, Cleopatra January 2015 (has links)
A thesis submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2015. / It is recognised that tooth loss as a consequence of oral diseases affects quality of life in humans. This has directed studies towards biological tooth replacement in vivo. In humans and other mammals, tooth replacement occurs only once (diphyodonty) as opposed to non-mammalian vertebrates where tooth replacement continues throughout life (polyphyodonty). Detailed knowledge of tooth initiation, development and morphology amongst vertebrates and especially amniotes, is necessary to understand the tooth replacement process. Crocodilians provide an interesting model for tooth replacement studies as they also exhibit thecodonty. Regulation of polyphyodonty has not been genetically defined, and it is uncertain whether the molecular mechanisms of continuous tooth replacement are similar to those involved in the primary dentition. The aim of this study was therefore to analyse crocodilian odontogenesis in detail, with the aid of light microscopy and CT scans, in order to provide a structural framework for molecular processes regulating polyphyodonty. Crocodile probes to bmp4 and pitx2 were designed, generated and labelled for use in in situ hybridisation. The expression patterns of pitx2 and bmp4 in embryos and hatchlings of the polyphyodont Nile crocodile (Crocodylus niloticus) were examined at different stages of tooth development. Histologically crocodilian tooth development appears similar to mammals. Interesting variations include the initiation of odontogenesis in the ectomesenchyme, the presence of dental placodes, the ‘null generation teeth’, the two different bell-stage tooth germs and the tooth-family organisation. A direct 1:1 relationship between the status of the erupted tooth and the developmental phase of the replacement tooth was not seen. However in more mature teeth, the replacement tooth germs were at a more advanced developmental stage than those associated with less mature teeth. Molecular data revealed that pitx2 was expressed in the oral epithelium and the dental placode. Bmp4 expression was not evident in the dental placode, but was localised in the odontoblasts of early bell stage tooth germs. Pitx2 and bmp4 were expressed in both the odontoblast and ameloblast layers in late bell stage tooth germs. Expression of pitx2 and bmp4 is conserved across vertebrates and pitx2 may play a role in initiation of primary and successional teeth.
276

Significado da alopecia para mulheres submetidas à quimioterapia para o câncer ginecológico ou mamário / Meaning of hair loss in women undergoing chemotherapy for breast or gynecological cancer

Sampaio, Barbara Alexandre Lespinassi 02 August 2013 (has links)
Estudo qualitativo, cujo objetivo foi compreender o significado da alopecia, decorrente de quimioterapia, para mulheres submetidas a esse tipo de tratamento para o câncer ginecológico ou mamário, e teve como referencial teórico o Interacionismo Simbólico. Os dados foram obtidos por meio de entrevistas e prontuários de 15 mulheres que apresentaram alopecia como evento adverso ao tratamento quimioterápico, e frequentavam um serviço especializado em reabilitação pós-mastectomia ou um ambulatório ou enfermaria de oncologia de um hospital universitário do interior de São Paulo. Foram identificadas duas unidades temáticas pela Análise de Conteúdo: 1) o significado da alopecia para as mulheres que a apresentam, na relação consigo próprias; e 2) na relação com os outros e com o mundo. Na relação consigo próprias, a alopecia significou necessidade de lidar com alterações emocionais e da autoestima, necessidade de disfarce, dificuldade de lidar com a alopecia, de se olhar no espelho e de falar sobre o assunto, sendo que a mulher descobriu formas de lidar com os problemas ocasionados pela queda de cabelo, embora este tenha sido um problema que muitas vezes trouxe sofrimento maior do que o câncer em si. Já na relação com os outros e com o mundo, a alopecia foi tida como um estigma relacionado ao câncer e seus tratamentos, trouxe mudanças nos hábitos e rotinas, além de interferir na sexualidade. Assim, puderam ser identificadas instituições que ofereceram apoio às mulheres. Compreender o significado pleno da experiência de alopecia na vida cotidiana dessas mulheres é fundamental para poder proporcionar-lhes apoio durante o curso da doença, e para auxiliá-las no desenvolvimento de estratégias para lidar com as mudanças que ocorrem durante o tratamento do câncer. / Qualitative study aimed to understand the meaning of hair loss because chemotherapy for women undergoing this type of treatment for breast or gynecological cancer, and had the theoretical Symbolic Interaction. Data were collected through interviews and medical records of15 women who had hair loss as an adverse event to chemotherapy, and attended a specialized rehabilitation postmastectomy or a clinic or oncology ward of a university hospital in São Paulo. Two thematic units were identified by Content Analysis: 1) the meaning of hair loss for women, in relation to themselves, and 2) the relationship with others and with the world. In relation to themselves, hair loss meant the necessity to deal with emotional and self-esteem, the necessity to disguise, difficulty to deal with alopecia, to look in the mirror and talk about it, although the woman discovered ways of dealing with the problems caused by hair loss, this has been a problem that often caused more suffering than the cancer. In the relation with others and with the world, the hair loss was seen as a stigma related to cancer and its treatments, caused changes in habits and routines, as well as interfere with sexuality. Therefore could be identified institutions which offered support for women. Understand the full meaning of the experience of hair loss in women\'s daily life is crucial to be able to provide them support during the course of the disease, and to assist them in developing strategies to deal with the changes that occur during cancer treatment
277

Estudo epidemiológico e genético da surdez em dois municípios do estado da Paraíba, Brasil / Epidemiologic and genetic study of deafness in two counties in the state of Paraíba, Brazil

Melo, Uirá Souto 21 August 2013 (has links)
Os estados do Nordeste brasileiro concentram elevadas taxas de pessoas com deficiências, mas pouco se estudou a respeito de suas causas. O objetivo desse estudo foi determinar a prevalência da deficiência auditiva e estimar a contribuição dos fatores genéticos na sua etiologia nas populações de dois municípios do Nordeste brasileiro. Após indicação pelos agentes comunitários de saúde para avaliação clínico-genética, foram avaliados 182 indivíduos com perda auditiva manifestada antes dos 60 anos dos municípios de Gado Bravo (76 pacientes) e Queimadas (106 pacientes), com população de 8.376 e 41.049 habitantes, respectivamente. Em Queimadas, 13 pacientes eram homozigotos com a mutação c.35delG no gene GJB2 (13/106, 12,2%; 6/81, 7,4% das famílias). Já em Gado Bravo, somente um paciente era homozigoto com esta mutação (1/76, 1,3%; 1/55, 1,8% das famílias). A mutação m.A1555G no gene mitocondrial MTRNR1 e a mutação c.167delT no gene GJB2 não foram detectadas em ambos os municípios. Quanto às deleções do GJB6, apenas a del(GJB6-D13S1854) foi encontrada em quatro casos em Gado Bravo (4/76, 5,3%; 2/55, 3,6% das famílias). Após o sequenciamento completo do gene GJB2, foi detectada a mutação p.W24X (c.G71A) em heterozigose em três casos isolados do município de Gado Bravo (3/76, 3,9%). Em resumo, mutações patogênicas no lócus DNFB1 foram encontradas em 16% (34/212) dos alelos testados no município de Queimadas e em 9,9% (15/152) dos alelos testados no município de Gado Bravo. No total da casuística, ocorreram 11 pacientes com uma única mutação recessiva detectada (monoalélica) no lócus DFNB1. As amostras desses 11 pacientes foram submetidas à análise de MLPA na tentativa de identificar uma segunda mutação, do tipo variação do número de cópias, mas nenhuma mutação foi encontrada. O gene SLC26A4 foi sequenciado em amostras de famílias com padrão de herança autossômico recessivo sem mutação detectada no lócus DFNB1, que apresentaram ligação compatível por meio de microssatélites na região próxima a esse gene. Não foi detectada nenhuma mutação patogênica na região de código desse gene. Após o estudo de ligação por meio de array de SNPs e microssatélites em uma família com quatro afetados pela síndrome de Usher do município de Gado Bravo, o gene CLRN1 apareceu como provável candidato e as amostras desses pacientes foram selecionadas para sequenciamento. Foi detectada a mutação p.Y63X em homozigose nos quatro pacientes. As amostras dos outros pacientes com essa síndrome também foram sequenciadas. Essa mutação foi encontrada em homozigose em 21 dos 23 casos de síndrome de Usher em Gado Bravo. A porcentagem de casos de surdez com provável etiologia genética em Gado Bravo e Queimadas foi estimada em 55% e 45%, respectivamente / The states of the Brazilian Northeast concentrate high rates of people with disabilities, but little has been investigated about their causes. The aim of this study was to determine the prevalence of hearing impairment and estimate the contribution of genetic factors in its etiology in populations from two counties in the Northeast of Brazil. After indication from community health agents, 182 individuals were evaluated, presenting hearing loss before the age of 60 in the counties of Gado Bravo (76 patients) and Queimadas (106 patients), with populations of 8,376 and 41,049 inhabitants, respectively. In Queimadas, 13 homozygotes with the c.35delG mutation in the GJB2 gene were found (13/106, 12.2%, 6/81, 7.4% of probands). As for Gado Bravo (N = 76), only one patient was homozygous with this mutation (1/76, 1.3%, 1/55, 1.8% of probands). The m.A1555G mutation in the mitochondrial gene MTRNR1, and the c.167delT mutation in the GJB2 gene were not detected in both counties. As for GJB6 deletions, only the del(GJB6-D13S1854) was found in four cases from Gado Bravo (4/76, 5.3%, 2/55, 3.6% of probands). After the complete sequencing of the GJB2 gene, the p.W24X (c.G71A) mutation was detected in three isolated heterozygous cases of the Gado Bravo county (3/76, 3.9%). In two of these cases, the mutation was present along with a second recessive mutation in the DNFB1 locus. In short, pathogenic mutations in the DNFB1 locus were found in 16% (34/212) of the alleles tested in the county of Queimadas and 9.9% (15/152) of the alleles tested in the county of Gado Bravo. No pathogenic mutation was detected in the coding region of this gene. From all cases, there were 11 patients with a single recessive mutation detected (monoallelic) in DFNB1 locus. Samples of these 11 patients were analyzed for MLPA in attempt to identify a second mutation, with copy number variation, but no mutation was found. The SLC26A4 gene was sequenced in families samples with autosomal recessive hearing loss, with no mutation detected in the DFNB1 locus, presenting compatible linkage utilizing microsatellites near this gene region. After linkage study using SNPs arrays and microsatellites in a family with four affected by the Usher syndrome in Gado Bravo, the CLRN1 gene appeared as a candidate and samples of these patients were selected for sequencing. The p.Y63X mutation was detected in the homozygosis in the four individuals. Samples from other patients with this syndrome were also sequenced and this mutation was found in homozygosis 21 out of 23 cases of Usher syndrome in Gado Bravo. The percentage of cases with a probable genetic cause for hearing loss in Gado Bravo and Queimadas was estimated at 55% and 45%, respectively.
278

Role of oxidative stress in the balding dermal papilla

Upton, Jamie January 2012 (has links)
The dermal papillae of the hair follicle control its growth, differentiation and apoptosis via a range of growth factors. These secreted growth factors are known to differ between those of non-balding scalp and those of balding scalp and can even differ in response to a common stimuli – androgen. In balding scalp androgen stimulates the secretion of negative growth factors, while in non-balding scalp androgen is found to exert little or no effect. Dermal papilla cells (DPCs) can be cultured in vitro, however those from balding scalp have been found to undergo premature senescence compared to those from non-balding scalp. A major cause of premature senescence is oxidative stress – the gradual accumulation of reactive oxygen species within the cell causing deleterious loss of function. Reactive oxygen species are known to be mediated in response to androgens and growth factors and in turn may affect growth factor signalling within the cell. Using low oxygen cell culture as a means of reducing oxidative stress, balding and non-balding DPCs were grown and characterised. It was confirmed that low oxygen culture could increase proliferation, delay senescence and reduce reactive oxygen species with both DPC types and that balding DPCs showed a higher sensitivity to oxidative stress. It was also found that secretions of growth factors by the balding DPCs in response to different oxygen conditions differed greatly to that of the occipital DPCs. Androgen, but not TGF-β was found to modulate DPC production of catalase, an antioxidant, under low oxygen conditions and this caused a reduction in reactive oxygen species in the balding DPCs. Balding DPCs also demonstrated an upregulation of the antioxidant total glutathione, however had a reduced fraction of the active reduced form of the molecule. In addition, it was shown for the first time 3 that under cell culture conditions balding DPCs express TGF-β receptors and it was shown that proliferation and migration of the balding DPCs could be affected by addition of exogenous TGF-β, highlighting a potential role for TGF-β as an autocrine growth factor in the balding dermal papilla.
279

Correction of the multiple scattering effects in the electron energy loss spectroscopy in the low loss region. / 低能电子能量损失谱中多重散射效应的修正 / Correction of the multiple scattering effects in the electron energy loss spectroscopy in the low loss region. / Di neng dian zi neng liang sun shi pu zhong duo zhong san she xiao ying de xiu zheng

January 2006 (has links)
An Xipo = 低能电子能量损失谱中多重散射效应的修正 / 安西坡. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 55-56). / Text in English; abstracts in English and Chinese. / An Xipo = Di neng dian zi neng liang sun shi pu zhong duo zhong san she xiao ying de xiu zheng / An Xipo. / Abstract --- p.i / 摘要 --- p.ii / Acknowledgement --- p.iii / Table of contents --- p.iv / Chapter Chapter 1: --- Introduction --- p.1 / Chapter Chapter 2: --- Background / Chapter 2.1 --- Theory of electron scattering --- p.3 / Chapter 2.1.1 --- Elastic scattering --- p.3 / Chapter 2.1.2 --- Inelastic scattering --- p.4 / Chapter 2.1.2.1 --- The bethe theory --- p.5 / Chapter 2.1.2.2 --- The dielectric formulation --- p.6 / Chapter 2.1.3 --- Excitation of out-shell electrons --- p.6 / Chapter 2.1.3.1 --- Volume plasmon and its dispersion --- p.6 / Chapter 2.1.3.2 --- Single electron excitation --- p.8 / Chapter 2.2 --- Single and multiple scattering process --- p.8 / Chapter Chapter 3 --- Fourier transform based deconvolution method / Chapter 3.1 --- Theory --- p.10 / Chapter 3.1.1 --- Derivation of the single scattering distribution (SSD) --- p.10 / Chapter 3.1.2 --- K-K analyais --- p.12 / Chapter 3.2 --- Effectiveness of the F-log algorithm and data interpretation --- p.13 / Chapter 3.2.1 --- Removal of the plural scattering using F-log --- p.13 / Chapter 3.2.2 --- Deduction of the dielectric function --- p.14 / Chapter 3.3 --- Shortcomings and limitations --- p.15 / Chapter 3.3.1 --- Spectrum collection range --- p.15 / Chapter 3.3.2 --- Artificial peaks in the low energy range (0-5 eV) --- p.18 / Chapter 3.3.3 --- Thin specimens --- p.19 / Chapter 3.3.4 --- Spectra taken at q>0 --- p.22 / Chapter Chapter 4 --- Direct deconvolution method / Chapter 4.1 --- Theory --- p.26 / Chapter 4.2 --- Results and discussion --- p.31 / Chapter 4.2.1 --- Results of the original direct deconvolution algorithm --- p.31 / Chapter 4.2.2 --- Results of the revised direct deconvolution algorithm --- p.32 / Chapter 4.2.2.1 --- Removal of the plural scattering of the spectra taken at zero momentum transfer --- p.32 / Chapter 4.2.2.2 --- Removal of the plural scattering of the spectra taken at q>0 --- p.38 / Chapter 4.2.3 --- Evaluation of the revised direct deconvolution algorithm --- p.39 / Chapter Chapter 5 --- Elastic-inelastic interaction multiple scattering correction / Chapter 5.1 --- Theory --- p.44 / Chapter 5.2 --- Solution --- p.46 / Chapter 5.3 --- Results and discussion --- p.49 / Chapter Chapter 6 --- Conclusions --- p.52 / Reference --- p.54 / Appendix: / Chapter A1 --- The F-log deconvolution program code / Chapter A2 --- The Kramer-Kronig analysis program code / Chapter A3 --- The revised F-log program code to make allowance for the collection range problem / Chapter A4 --- Program code to reconstruct the ZLP / Chapter A5 --- The direct deconvolution program code
280

Exploring complex loss functions for point estimation

Chaisee, Kuntalee January 2015 (has links)
This thesis presents several aspects of simulation-based point estimation in the context of Bayesian decision theory. The first part of the thesis (Chapters 4 - 5) concerns the estimation-then-minimisation (ETM) method as an efficient computational approach to compute simulation-based Bayes estimates. We are interested in applying the ETM method to compute Bayes estimates under some non-standard loss functions. However, for some loss functions, the ETM method cannot be implemented straightforwardly. We examine the ETM method via Taylor approximations and cubic spline interpolations for Bayes estimates in one dimension. In two dimensions, we implement the ETM method via bicubic interpolation. The second part of the thesis (Chapter 6) concentrates on the analysis of a mixture posterior distribution with a known number of components using the Markov chain Monte Carlo (MCMC) output. We aim for Bayesian point estimation related to a label invariant loss function which allows us to estimate the parameters in the mixture posterior distribution without dealing with label switching. We also investigate uncertainty of the point estimates which is presented by the uncertainty bound and the crude uncertainty bound of the expected loss evaluated at the point estimates based on MCMC samples. The crude uncertainty bound is relatively cheap, but it seems to be unreliable. On the other hand, the uncertainty bound which is approximated a 95% confidence interval seems to be reliable, but are very computationally expensive. The third part of the thesis (Chapter 7), we propose a possible alternative way to present the uncertainty for Bayesian point estimates. We adopt the idea of leaving out observations from the jackknife method to compute jackknife-Bayes estimates. We then use the jackknife-Bayes estimates to visualise the uncertainty of Bayes estimates. Further investigation is required to improve the method and some suggestions are made to maximise the efficiency of this approach.

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