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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.
41

Stratigraphic and geochemical framework of the Palaeoproterozoic rise in atmospheric oxygen, Transvaal Supergroup (South Africa)

Warke, Matthew January 2017 (has links)
The Transvaal Supergroup (South Africa) records evidence of trace oxygen production in late Neoarchaean strata, approximately 200 million years before the 'Great Oxidation Event' (GOE) which is recorded within the Palaeoproterozoic Duitschland Formation (Transvaal Supergroup) between ~2.42 and 2.32 Ga. It is hypothesized that there was a secular rise in oxygen concentrations between the late Neoarchaean and the GOE which may be recorded within the 'mid-Transvaal' Supergroup (Tongwane Formation, Duitschland Formation, Koegas Subgroup). This project has integrated field sedimentology, petrography and geochemistry to build new or revised depositional and diagenetic frameworks for each of these successions and has assessed palaeoredox conditions using carbon isotopes and rare earth element and yttrium (REY) patterns and anomalies. Despite a complex paragenetic history, including medium-grade contact metamorphism, the Tongwane Formation preserves primary (or near-primary), carbon isotope (delta13Ccarb = ~0 ± 2 ‰VPDB) and REY patterns that are consistent with Palaeoproterozoic seawater. No anomalously positive delta13Ccarb values or cerium (CeSN) anomalies are preserved, suggesting limited build-up of free O2. The lower Duitschland Formation preserves previously undocumented lithofacies variations and an angular mid-Duitschland unconformity (which is contemporaneous with the GOE). A new depositional model is proposed; facies assemblages and geometries are consistent with deposition of a wave-influenced Gilbert fan delta deposited in an isolated depocentre created by localised extensional fault subsidence. Lower Duitschland Formation limestones and dolomites show depleted delta13Ccarb and delta18Ocarb values and marine REY patterns which lack CeSN anomalies. Negative delta13Ccarb values suggest incorporation of 12C from organic matter during early diagenesis. There is no evidence of significant free oxygen production. The Koegas Subgroup is unconformably overlain by glacial strata of the Postmasburg Subgroup; the two successions are not intercalated and therefore not synchronous. Marine REY signals with positive Ce anomalies are recorded in delta13Ccarb depleted, stromatolitic dolomite exposed on the farms Taaibosfontein and Sandridge. Small magnitude positive anomalies are likely calculation artefacts, though anomalies >30 % may reflect redox stratification. Neoarchaean cuspate stromatolites of the Gamohaan Formation record trace element distributions - imaged using synchrotron-based XRF techniques - that map to primary microbial structures are not attributable to syndepositional or diagenetic mineralisation processes. Thus they may prove to be indicators of specific microorganisms and metabolic processes, e.g. photosynthetically relevant metals (e.g. Mn, Cu, Ni) mapped in biogenic structures may serve as a 'fingerprint' of cyanobacterial oxygenic photosynthesis. Overall, no evidence is seen for a secular rise in oxygen in the mid-Transvaal. However, depositional frameworks and diagenetic processes have been determined and the retention of marine signals established within the Tongwane, Duitschland and Koegas successions. Therefore the findings of this project constitute a robust framework for future palaeoredox studies of the mid-Transvaal Supergroup.
42

EXPRESSÃO DO ANTÍGENO A1: frequência em recém-nascidos / ANTIGEN EXPRESSION A1: frequency of newborns

Mikalauscas, Márcia Maria Vasconcellos 31 August 2011 (has links)
Within the ABO system there are several blood subgroups: subgroup A, subgroup B and subgroup H, and the most frequently encountered in practice are the subgroups A1, A2, A1B and A2B. The cells of, approximately, 80% of adults in group A are A1. The remaining 20% are A2 or weaker subgroups. However, in newborns is very little literature about the frequency of the subgroups of A. At birth most of the blood group A infants seems to present itself as belonging to subgroup A2, since all the ABO antigens are not fully developed in this period. Since iron deficiency, widespread in this age group, often discussed by the scientific community is related to the disproportion between the expansion of erythroid mass and iron obtained from the diet. Around four months of age, iron stores are reduced by half, and the exogenous iron is required to maintain hemoglobin concentration during this phase of rapid growth, between four and 12 months. Our objectives were to determine the frequency of newborns belonging to subgroups A1 and A2, to identify the frequency of antigen expression A1, between six and 12 months of age, infants initially typed as belonging to subgroup A2 and check the hemoglobin levels for the detection of anemia in these children. The results showed that the frequency of newborn belonging to the A1 blood subgroup was 67% (319) and the A2 subgroup was 33% (152), from a total of 471 newborns belonging to blood group A. We found a great predominance of the A1 subgroup, contradicting the literature that reports the prevalence of subgroup A2 in newborn infants. Regarding the identification of the frequency of A1antigen expression, between six and 12 months of age (n = 40), the percentage of children who express the A1 antigen, after being with six months to one year of age was 67.5% (27), the rest remained as A2 (13). The verification of hemoglobin levels in these children (n = 71), by the method of cianometa-hemoglobin, resulting in 34% of anemic children, pointing to the presence of anemia in this age group. The rates found ranged from 6.56 g/dl to 10.8 g/dl. Thus, in relation to A1 antigen expression between six and 12 months of age further studies are needed, and for the prevalence of anemia is necessary to emphasize in public health programs, intervention measures and more effective control of this nutritional disorder. / Dentro do sistema ABO existem diversos subgrupos sanguíneos: subgrupos A, subgrupos B e subgrupo H, sendo que os mais frequentemente encontrados na prática são os subgrupos A1, A2, A1B e A2B. As células de, aproximadamente, 80% da população adulta do grupo A são A1. Os 20% restantes são A2 ou subgrupos mais fracos. Porém, em recém-nascidos é muito escassa a literatura a respeito de dados quanto à frequência dos subgrupos de A . A maioria dos lactentes do grupo sanguíneo A parece apresentar-se como pertencente ao subgrupo A2, no nascimento, já que todos os antígenos ABO não estão completamente desenvolvidos neste período. Já a carência de ferro, generalizada nesse grupo etário, muitas vezes discutida pela comunidade científica, é relacionada à desproporção entre a expansão da massa eritróide e o ferro obtido da dieta. Por volta dos quatro meses de idade, os estoques de ferro estão reduzidos pela metade, e o ferro exógeno é necessário para manter a concentração de hemoglobina durante esta fase de rápido crescimento, entre quatro e 12 meses. Os objetivos deste trabalho foram determinar a frequência de recém-nascidos pertencentes aos subgrupos A1 e A2; identificar a frequência da expressão do antígeno A1, no período entre seis e 12 meses de idade, em lactentes inicialmente tipados como pertencentes ao subgrupo A2 e verificar os níveis de hemoglobina para a detecção de anemia nestas crianças. Os resultados mostraram que a frequência de recém-nascidos pertencentes ao subgrupo sanguíneo A1 foi de 67% (319) e para o subgrupo A2 foi de 33% (152), de um total de 471 recém-nascidos pertencentes ao grupo sanguíneo A. Constatou-se uma grande predominância do subgrupo A1, contrariando a literatura que relata a prevalência de subgrupo A2 em recém-nascidos. Em relação à identificação da frequência da expressão do antígeno A1, no período entre seis e 12 meses de idade (n=40), a porcentagem de crianças que passaram a expressar o antígeno A1, depois de estarem com seis meses a um ano de idade foi de 67,5% (27), o restante permaneceu como A2 (13). A verificação dos níveis de hemoglobina nestas crianças (n=71), através do método da cianometa-hemoglobina, resultou em 34% de crianças anêmicas, apontando a presença de anemia para essa faixa etária. Os índices encontrados variaram de 6,56g/dl a 10,8g/dl. Assim, em relação à expressão do antígeno A1 entre seis e 12 meses de idade são necessários mais estudos; e, para a prevalência da anemia é necessário enfatizar, nos programas de saúde pública, medidas de intervenção mais eficazes e controle desse distúrbio nutricional.
43

Sobre grupos unicamente cobertos / On uniquely covered groups

JardÃnia Sobrinho Goes 20 December 2011 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Este trabalho à baseado no artigo "Uniquely Covered Groups" de M. A. Brodie, que investiga grupos finitos que possuem uma Ãnica cobertura irredundante por subgrupos prÃprios. O resultado principal obtido por M. A. Brodie assegura que um grupo finito e nÃo nilpotente G à unicamente coberto se, e somente se, G/Z(G) à um grupo nÃo abeliano de ordem pq, onde p e q sÃo primos distantes e {x,Z(G) à cÃclico para todo x â G. Nosso propÃsito à apresentar a demonstraÃÃo e uma aplicaÃÃo deste teorema. / This work is based on the article "Uniquely Covered Groups" due to M. A. Brodie, which investigates finite groups that have a single irredundante coveraging by subgroups. The main result obtained by M. A. Brodie asserts that a non-nilpotent finite group G is uniquely covered if and only if, G/Z(G) is a non-Abelian group of order pq, where p and q are distinct primes and {x,Z(G) is cyclic for every x â G. Our purpose is to present the proof and application of this theorem.
44

Estudo hidrogeológico do Subgrupo Itararé no médio Rio Tietê, Município de Tietê, SP / Itararé Subgroup hydrogeological study in the Middle Tietê river\'s of the Tietê municipalitie, São Paulo State

Helio Nobile Diniz 14 November 1990 (has links)
Os sedimentos da Formação Tietê, do Subgrupo Itararé, do Grupo Tubarão, tem uma primordial importância nos locais onde afIoram porque nos mesmos ocorre a captação de água subterrânea para o abastecimento das populações locais. As captações de superfície, nestes locais, atualmente estão em desuso, face à intensa poluição dos mananciais, muitas vezes proveniente de outros municípios situados a montante. Esta poluição é causada pelo lançamento de efIuentes domésticos e industriais nos rios, sem qualquer tratamento, principalmente nas áreas urbanas das cidades ribeirinhas. Em conseqüência, é grande a procura de água subterrânea, tanto para abastecimento das populações urbanas, quanto para o suprimento da demanda agrícola e industrial. A variação faciológica dos sedimentos glaciais do Subgrupo Itararé produz uma ampla faixa de vazões nas captações de água subterrânea e, frente às dificuldades para a prospecção da água subterrânea nestes sedimentos, deve-se empregar métodos avançados de pesquisa para avaliação do potencial hidríco subterrâneo e localizar melhor as futuras captações. O Instituto Geológico, graças a muitos anos de trabalho na área do Município de Tietê e regiões circunvizinhas, acumulou dados que permitem um estudo científico amplo sobre a geologia e hidrogeologia local. Este trabalho enfoca os aspectos geológicos regionais e locais, possibilitando uma ampla discussão sobre a faciologia dos sedimentos do Subgrupo Itararé na região do Médio Rio Tietê, no Município de Tietê. É dedicada atenção especial aos sedimentos da Formação Tietê, o aqüífero local por excelência, e quanto aos aspectos qualitativos e quantitativos das águas subterrâneas. Neste trabalho foram empregados métodos apropriados de pesquisa para a caracterização hidrogeológica dos sedimentos e para o conhecimento do potencial de uso da água subterrânea. Estes métodos envolveram levantamentos geológicos, geral e de detalhe, estudos e interpretações de dados hidrológicos, interpretação de dados de ensaios de bombeamento em poços tubulares profundos e, estudos hidroquímicos e isotópicos visando caracterizar e definir a origem das águas subterrâneas. / The present paper is a contribution to the hydrogeology of Tietê Municipality, State of São Paulo, Brazil. The main subject of this research is the Permocarboniferous Itararé Subgroup of the Tubarão Group, specially the Tietê Formation due to its groundwater potential. Surface water sources, including the most of the rivers, are not fitted for consumption because of the high pollution degree. As a consequence, the search for groundwater became of utmost importance. The State of São Paulo \"Instituto Geológico\" supports a Itararé field work program covering the Middle Tiete Valley region for a long time. Extensive boreholes data allowed an evaluation of the local Itararé facies relationships. The present paper intends to study the Tietê Municipality hydrogeology in order to open an extensive discussion of the Itararé Subgroup facies whit especial reference to the Tietê Formation. This paper intends to fix the most suitable searching methods to characterize the best hydrogeologic potential of these sediments, so important to get potable water for the Tietê Municipality. The field work includes the interpretation of pumping data from deep wells and characterization of isotopic and chemical attributes of the groundwater in order to improve our knowledge of its origin and chemical composition including the salt contents.
45

A Concave Pairwise Fusion Approach to Clustering of Multi-Response Regression and Its Robust Extensions

Chen, Chen, 0000-0003-1175-3027 January 2022 (has links)
Solution-path convex clustering is combined with concave penalties by Ma and Huang (2017) to reduce clustering bias. Their method was introduced in the setting of single-response regression to handle heterogeneity. Such heterogeneity may come from either the regression intercepts or the regression slopes. The procedure, realized by the alternating direction method of multipliers (ADMM) algorithm, can simultaneously identify the grouping structure of observations and estimate regression coefficients. In the first part of our work, we extend this procedure to multi-response regression. We propose models to solve cases with heterogeneity in either the regression intercepts or the regression slopes. We combine the existing gadgets of the ADMM algorithm and group-wise concave penalties to find solutions for the model. Our work improves model performance in both clustering accuracy and estimation accuracy. We also demonstrate the necessity of such extension through the fact that by utilizing information in multi-dimensional space, the performance can be greatly improved. In the second part, we introduce robust solutions to our proposed work. We introduce two approaches to handle outliers or long-tail distributions. The first is to replace the squared loss with robust loss, among which are absolute loss and Huber loss. The second is to characterize and remove outliers' effects by a mean-shift vector. We demonstrate that these robust solutions outperform the squared loss based method when outliers are present, or the underlying distribution is long-tailed. / Statistics
46

Skew Relative Hadamard Difference Set Groups

Haviland, Andrew 17 April 2023 (has links) (PDF)
We study finite groups $G$ having a nontrivial subgroup $H$ and $D \subset G \setminus H$ such that (i) the multiset $\{ xy^{-1}:x,y \in D\}$ has every element that is not in $H$ occur the same number of times (such a $D$ is called a {\it relative difference set}); (ii) $G=D\cup D^{(-1)} \cup H$; (iii) $D \cap D^{(-1)} =\emptyset$. We show that $|H|=2$, that $H$ has to be normal, and that $G$ is a group with a single involution. We also show that $G$ cannot be abelian. We give examples of such groups, including certain dicyclic groups, by using results of Schmidt and Ito. We describe an infinite family of dicyclic groups with these relative difference sets, and classify which groups of order up to $72$ contain them. We also define a relative difference set in dicyclic groups having additional symmetries, and completely classify when these exist in generalized quaternion groups. We make connections to Schur rings and prove additional results.
47

Plant Virus Diagnostics: Comparison of classical and membrane-based techniques for immunoassay and coat protein sequence characterization for Cucumber mosaic virus and three potyviruses

Chang, Peta-Gaye Suzette 06 July 2009 (has links)
Diagnostics is important in the development and implementation of pest management strategies. The virus diagnostic capabilities of several plant pathology collaborators within the Integrated Pest Management Collaborative Research Support Program (IPM CRSP) host countries were evaluated with the aid of a survey. Very few plant disease diagnostic clinics had funds to cover daily operations despite over half of the responding clinics receiving an operational budget. Academically and government affiliated clinics within the developing host countries had little access to molecular tools and equipment, relying mostly on biological and serological methods. Clinics affiliated with private companies and within the USA relied more upon molecular assays. Ten CMV isolates identified by tissue blot immunoassay (TBIA) were collected from a garden at the Historic Smithfield Plantation on the Virginia Tech campus, and from Painter, Virginia on the Eastern Shore. Three CMV isolates from Smithfield were biologically compared to six early CMV isolates stored since the 1970s, while all isolates were compared serologically and molecularly. Sequences obtained after reverse transcription-polymerase chain reaction (RT-PCR) assigned the CMV isolates into subgroups, with eleven to subgroup 1A and three to subgroup 2. The subgroup assignments were confirmed by TBIA using CMV subgroup-specific monoclonal antibodies (Agdia Inc). At Smithfield Plantation, another virus, Turnip mosaic virus (TuMV) was identified from Dame's Rocket (Hesperis matronalis L.). This is the first report of TuMV in Virginia.  In TBIA virus-infected plant samples are blotted onto nitrocellulose membranes, dried, and processed. Membranes can be stored for long periods of time and transported safely across borders without risk of introducing viruses into new environments, but virus remains immunologically active for several months. Methods were developed with CMV and three potyviruses, using the same membranes, for detecting viral RNA by RT-PCR and direct sequencing of PCR products.. Amplification by RT-PCR  was possible after membrane storage for up to 15 months. The membranes also performed well with samples sent from IPM CRSP host countries and within the USA. This method should improve molecular diagnostic capabilities in developing countries, as samples can be blotted to membranes and sent to a centralized molecular laboratory for analysis. / Ph. D.
48

Determining Group Structure From the Sets of Character Degrees

Aziziheris, Kamal January 2010 (has links)
No description available.
49

Finding a Targeted Subgroup with Efficacy for BinaryResponse with Application for Drug Development

Kil, Siyoen January 2013 (has links)
No description available.
50

Discovery of an expanded set of avian leukosis subgroup E proviruses in chickens using Vermillion, a novel sequence capture and analysis pipeline

Rutherford, K., Meehan, Conor J., Langille, M.G.I., Tyack, S.G., McKay, J.C., McLean, N.L., Benkel, K., Beiko, R.G., Benkel., B. 05 November 2019 (has links)
No / Transposable elements (TEs), such as endogenous retroviruses (ERVs), are common in the genomes of vertebrates. ERVs result from retroviral infections of germ-line cells, and once integrated into host DNA they become part of the host's heritable genetic material. ERVs have been ascribed positive effects on host physiology such as the generation of novel, adaptive genetic variation and resistance to infection, as well as negative effects as agents of tumorigenesis and disease. The avian leukosis virus subgroup E family (ALVE) of endogenous viruses of chickens has been used as a model system for studying the effects of ERVs on host physiology, and approximately 30 distinct ALVE proviruses have been described in the Gallus gallus genome. In this report we describe the development of a software tool, which we call Vermillion, and the use of this tool in combination with targeted next-generation sequencing (NGS) to increase the number of known proviruses belonging to the ALVE family of ERVs in the chicken genome by 4-fold, including expanding the number of known ALVE elements on chromosome 1 (Gga1) from the current 9 to a total of 40. Although we focused on the discovery of ALVE elements in chickens, with appropriate selection of target sequences Vermillion can be used to develop profiles of other families of ERVs and TEs in chickens as well as in species other than the chicken. / Financial support was provided by the EW GROUP, as well as grants from the Canada Foundation for Innovation, Canada Research Chairs Program, and the Natural Sciences and Engineering Council of Canada to RGB, and Canada Institutes of Health Research funding to MGIL and CJM.

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