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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.
181

Mecanismos e efeitos da internalização de nanotubos de carbono de parede simples sobre o ciclo celular. / Mechanisms and effects of internalization of single wall carbon nanotube in cell cycle.

Souza, Marcelo Medina de 05 December 2014 (has links)
O presente trabalho teve por objetivo avaliar alterações devido à exposição a Nanotubos de Carbono de Parede Simples (NTCPS) em duas linhagens celulares epiteliais (BBnt e HK2) e em uma linhagem celular monocítica (THP-1), enfocando os mecanismos de internalização e os efeitos sobre o ciclo celular. Foi avaliada a ação dos receptores scavenger na internalização dos NTCPS nas células HK2 e THP-1 e a interferência de duas concentrações de NTCPS sobre os elementos do citoesqueleto e no ciclo celular, nas células HK2 e BBnt. As concentrações utilizadas foram equivalentes as permitidas pelo The National Institute for Occupational Safety and Health: 2,4 e 24 mg/cm2. A análise de expressão de mRNA por RT-PCR para receptores scavenger, mostrou que a internalização do NTCPS pode ocorre por endocitose. Sendo que os receptores SCARA5 e SRA são os responsáveis pela internalização nas células THP-1, enquanto MARCO e SRA realizam o processo de internalização nas células HK2. Observou-se que em ambas as concentrações, as células BBnt apresentaram amplificação centrossômica, com a ocorrência de 25,38% e 28,46% de mitoses alteradas para cada concentração, respectivamente. Não houve interferência significativa na progressão do ciclo celular em ambas as linhagens. O estudo da interação dos NTCPS com vesículas lipídicas não apresentou evidencias de alterações ou danos na membrana das vesículas, porém as vesículas apresentaram-se associadas umas às outras após o tratamento com 24 mg/cm2. / This study aimed to assess changes due to exposure to of Single-wall Carbon Nanotubes (SWCNT) in two epithelial cell lines (BBnt and HK2) and a monocytic cell line (THP-1), focusing on the mechanisms of internalization and effects on the cell cycle. The action of scavenger receptors in the internalization of SWNTC in HK2 and THP-1 cells and the interference of two concentrations of SWNTC about elements of the cytoskeleton and the cell cycle, in BBnt and HK2 cells was evaluated. The concentrations used were equivalent to those allowed by The National Institute for Occupational Safety and Health: 2,4 to 24 mg/cm2. Analysis of mRNA expression by RT-PCR for scavenger receptors showed that the SWNTC internalization can occurs by endocytosis. Being that SCARA5 and SRA receptors are responsible for internalization in THP-1 cells, while MARCO and SRA perform the process of internalization in HK2 cells. It was observed that at both concentrations, the cells showed centrosome amplification in BBnt cells, with the occurrence of 25.38% and 28.46% of mitosis changed for each concentration, respectively. There was no significant interference with cell cycle progression in both strains. The study of the interaction of lipid vesicles with SWNTC showed no evidence of change or damage the membrane of the vesicles, but the vesicles were associated with each other after treatment with 24 mg/cm2.
182

Mecanismos e efeitos da internalização de nanotubos de carbono de parede simples sobre o ciclo celular. / Mechanisms and effects of internalization of single wall carbon nanotube in cell cycle.

Marcelo Medina de Souza 05 December 2014 (has links)
O presente trabalho teve por objetivo avaliar alterações devido à exposição a Nanotubos de Carbono de Parede Simples (NTCPS) em duas linhagens celulares epiteliais (BBnt e HK2) e em uma linhagem celular monocítica (THP-1), enfocando os mecanismos de internalização e os efeitos sobre o ciclo celular. Foi avaliada a ação dos receptores scavenger na internalização dos NTCPS nas células HK2 e THP-1 e a interferência de duas concentrações de NTCPS sobre os elementos do citoesqueleto e no ciclo celular, nas células HK2 e BBnt. As concentrações utilizadas foram equivalentes as permitidas pelo The National Institute for Occupational Safety and Health: 2,4 e 24 mg/cm2. A análise de expressão de mRNA por RT-PCR para receptores scavenger, mostrou que a internalização do NTCPS pode ocorre por endocitose. Sendo que os receptores SCARA5 e SRA são os responsáveis pela internalização nas células THP-1, enquanto MARCO e SRA realizam o processo de internalização nas células HK2. Observou-se que em ambas as concentrações, as células BBnt apresentaram amplificação centrossômica, com a ocorrência de 25,38% e 28,46% de mitoses alteradas para cada concentração, respectivamente. Não houve interferência significativa na progressão do ciclo celular em ambas as linhagens. O estudo da interação dos NTCPS com vesículas lipídicas não apresentou evidencias de alterações ou danos na membrana das vesículas, porém as vesículas apresentaram-se associadas umas às outras após o tratamento com 24 mg/cm2. / This study aimed to assess changes due to exposure to of Single-wall Carbon Nanotubes (SWCNT) in two epithelial cell lines (BBnt and HK2) and a monocytic cell line (THP-1), focusing on the mechanisms of internalization and effects on the cell cycle. The action of scavenger receptors in the internalization of SWNTC in HK2 and THP-1 cells and the interference of two concentrations of SWNTC about elements of the cytoskeleton and the cell cycle, in BBnt and HK2 cells was evaluated. The concentrations used were equivalent to those allowed by The National Institute for Occupational Safety and Health: 2,4 to 24 mg/cm2. Analysis of mRNA expression by RT-PCR for scavenger receptors showed that the SWNTC internalization can occurs by endocytosis. Being that SCARA5 and SRA receptors are responsible for internalization in THP-1 cells, while MARCO and SRA perform the process of internalization in HK2 cells. It was observed that at both concentrations, the cells showed centrosome amplification in BBnt cells, with the occurrence of 25.38% and 28.46% of mitosis changed for each concentration, respectively. There was no significant interference with cell cycle progression in both strains. The study of the interaction of lipid vesicles with SWNTC showed no evidence of change or damage the membrane of the vesicles, but the vesicles were associated with each other after treatment with 24 mg/cm2.
183

Evaluation of the effects of trehalose on the amplification of the 15 short tandem repeats loci of the AmpFℓSTR Identifiler Plus PCR Amplification Kit

Yoon, Gyeol 05 November 2016 (has links)
It is of great importance to be able to unambiguously interpret deoxyribonucleic acid (DNA) profiles, especially with Low Template (LT) DNA and mixture DNA that may contain major and minor contributors. Reducing stochastic effects, such as heterozygote peak imbalance, dropouts, and stutter artifacts have been studied by scientists in order to improve the evaluation of low quality DNA profile. There has been much research on a compatible solute, trehalose, in its effectiveness in enhancing the polymerase chain reaction (PCR), especially with GC-rich templates of DNA, and thermal stabilizing Thermus Aquaticus (Taq) DNA polymerases. Based on previous research, the effect of trehalose on peak heights, peak height ratios, and stutter ratios (n-1) from 15 short tandem repeats (STR) loci of the AmpFℓSTR® Identifiler® Plus PCR Amplification Kit was evaluated with 0.025ng, 0.05ng, 0.1ng, and 1ng of DNA, through the addition of 0M (control), 0.2M, and 0.4M of trehalose for each quantity of DNA. Although there was an observation regarding changes in average peak heights at 1ng of DNA with the addition of 0.2M, and 0.4M of trehalose, no conclusions could be made with the average peak heights for 0.025ng, 0.05ng, 0.1ng, and 1ng of DNA. The reason is that the propagation of pipetting error during the preparation of each batch could have contributed to the difference in the amount of DNA between each conditions which can be directly reflected in peak heights. Furthermore, unexpected discrepancy between the average peak heights for 0.1ng of DNA from the first and the second experiments rendered 0.1ng of DNA incompatible for comparison. With regards to average peak height ratios for 0.025ng, 0.05ng, 0.1ng, and 1ng of DNA, and average reverse stutter ratios for 0.1ng, and 1ng of DNA, there were no evidence to suggest that 0.2M or 0.4M of trehalose had any effects. Consistent trends for 0.1ng (Exp. 1 and 2) and 1ng of DNA from a statistical analysis through one-way ANOVA of individual loci, suggested that trehalose may have varying effects on certain loci. However, this observation must be approached with caution as it is uncertain whether unique trends across each data sets for certain loci were observed by chance due to small sample sizes or due to mechanisms of stutters and trehalose that are currently unknown. Future studies regarding the effect of trehalose on peak heights should be done with more precision through minimizing pipetting error, which can be accomplished by preparing one batch from which aliquots are taken. The result of the research does not show enough evidence to prove the usefulness of trehalose since the addition of trehalose does not yield consistently higher average peak heights and peak height ratios, and lower average reverse stutter ratios across 15 STR loci. Therefore, our results do not support that 0.2M and 0.4M of trehalose are useful within the parameter of forensic DNA analysis as they do not enhance the polymerase chain reaction (PCR) and improve stochastic effects for DNA profiles.
184

A new way to quantify stratosphere-troposphere coupling in observations and climate models

Clemo, Thomas Daniel January 2017 (has links)
Atmospheric mass is transported in and out of the stratospheric polar cap region by a wave-driven meridional circulation. Using composites of polar cap pressure anomalies, defined as deviations from the average annual cycle, it is shown that this stratospheric mass flux is accompanied by a similar mass flux near the surface. This 'tropospheric amplification' of the stratospheric signal is introduced as a new way to quantify stratosphere-troposphere coupling. Regression analysis is used to create a vertical profile of atmospheric pressure during a tropospheric amplification event, and the regression slope profile is used as a tool to quantify the amplification. Using data from 5 reanalysis datasets and 11 climate models, it is shown that high-top models, with a model lid of above 1 hPa, are significantly better at reproducing tropospheric amplification than low-top models, due to having more detailed parameterisations of stratospheric processes. However, the regression slope profiles of all models, bar one, are significantly different to the profile of reanalysis data at a 95% confidence level. Tropospheric amplification is also investigated in historical and future simulations from these models, and it is concluded that there is not expected to be a large change in the phenomenon over the next 100 years. The processes needed to reproduce tropospheric amplification can be identified by comparing idealised models of different complexity. A simple dry-core model is not able to reproduce tropospheric amplification, while a model with a comprehensive radiation scheme does produce the basic regression slope profile under certain configurations. The associations between pressure change and mass flux are further investigated using primitive equations. It is found that vertical and horizontal contributions to mass flux act to mostly cancel each other out, leaving a poorly-conditioned residual, and that the horizontal mass flux across the polar cap boundary has both geostrophic and ageostrophic components.
185

Design of microfluidic multiplex cartridge for point of care diagnostics

Ereku, Luck Tosan January 2017 (has links)
A simple, but innovative microfluidic Lab-on-a-chip (LOC) device which is broadly applicable in point of care diagnostics of biological pathogens was designed, fabricated and assembled utilising explicit microfluidic techniques. The purpose of this design was to develop a cartridge with the capability to perform multiplex DNA amplification reactions on a single device. To achieve this outcome, conventional laboratory protocols for sample preparation; involving DNA extraction, purification and elution were miniaturized to suit this lab-on-a-chip device of 75mm X 50mm cross-sectional area. The extraction process was carried out in a uniquely designed microchamber embedded with chitosan membrane that binds DNA at pH 5.0 and elutes when a different solution at pH 9.0 flows through. Likewise, purification protocol that occurs in the designed waste reservoir is very significant in biomedical field because it is concerned with waste treatment and cartridge disposability, was performed with a super absorbent powder that converts liquid to a gel like substance. This powder is known as sodium polyacrylate, which is also they treated with anti-bacterial chemicals to prevent environmental contamination. Furthermore, this process also employed the use of a passive valve for a precise fluid handling operation involving flow regulation from extraction to waste reservoir. In order to achieve the intended multiplexing function a multiplexer was created to distribute flow simultaneously through a bifurcated network of channels connected to six similar amplification microchambers. Prior to fabrication, computational fluid dynamics (CFD) simulation was utilized at flowrates less than 10μL/s as the means to test the effectiveness of each design components and also to specifically deduct empirical values that can be analyzed to improve or understand the relationship between the fluid and geometrical constraints of the microfluidic modular elements. The device produced was a hybrid cartridge composed of PDMS and glass which is the most widely used materials microfluidics research due to their low cost and simplicity of fabrication by soft lithography technique. The choice of material also took into account the various physical and chemical properties advantages and disadvantages in their bio-medical applications. Such properties include but not limited to surface energy that determines the wetting fluid characteristics, biocompatibility, optical transparency. Subsequently, after a prototype cartridge was developed fluid flow experimentation using liquid coloured dye was used on the fully fabricated cartridge to test the efficacy of its microfluidic functionalities before expensive DNA amplification reagents were utilised at similar flowrates to the CFD simulations. This gave rise to comparison between similar and dissimilar flow Peculiarities in the microfluidic circuit of both experiments. The final experiment was performed with the aid of a recent molecular technique in DNA amplification known as of RPA kit (recombinase polymerase amplification reaction). It involved performing two main reaction experiments; first, was the positive experiment that bears the sample DNA and the latter, negative that served as the control without DNA. In the end, quantitative analysis of results was done using an agarose gel that showed 143 base pairs, for the positive samples, thus validating the amplification experiment.
186

Heteroplasmia em Bombus morio (Hymenoptera, Apidae) e impactos em estudos evolutivos / Heteroplasmy in Bombus morio (Hymnoptera, Apidae) and impacts in evolutionary studies

Ricardo, Paulo Cseri 06 December 2017 (has links)
A utilização de sequências do DNA mitocondrial (mtDNA) como marcadores moleculares na investigação da diversidade genética e evolução é muito difundida, auxiliando na realização de inferências em inúmeros trabalhos. Apesar de sua inegável importância, a utilização dessas sequências como marcadores moleculares suscita algumas questões. A heteroplasmia, por exemplo, é reconhecida como um desafio na utilização de sequências do mtDNA. Este estado ocorre quando um organismo apresenta diferentes haplótipos mitocondriais. Em um trabalho anterior, foram encontrados indícios que sugeriam a presença de heteroplasmia na espécie de abelha Bombus morio. O trabalho atual investigou de forma mais detalhada a presença de heteroplasmia nessa espécie, assim como fatores que podem influenciar na identificação desse estado. Os resultados obtidos confirmaram a existência de heteroplasmia nessa espécie, e identificaram que alguns haplótipos heteroplásmicos foram compartilhados entre indivíduos de localidades distintas. Esses haplótipos heteroplásmicos compartilhados sugerem a existência de heteroplasmia estável em B. morio, o que pode influenciar inferências evolutivas, e em especial, os estudos populacionais. Também foi detectada a presença de NUMTs, pseudogenes nucleares resultantes da transferência de sequências do mtDNA para o genoma nuclear. Esses NUMTs apresentaram grande divergência de sequência em relação aos haplótipos mitocondriais, o que poderia afetar análises filogenéticas e populacionais, além da identificação de espécies por meio do DNA barcoding. Ainda, erros de amplificação podem ser falsamente interpretados como variação intraindividual do DNA mitocondrial (mtDNA), superestimando o número de haplótipos, principalmente quando polimerases de baixa fidelidade são utilizadas. Por fim, os resultados observados neste trabalho sugerem que a utilização de sequências do mtDNA deve ser utilizada de forma cautelosa, e indícios de heteroplasmia, como a presença de picos duplos, não devem ser ignorados. Quando essas evidências são observadas investigações mais detalhadas devem ser aplicadas, a fim de aferir qual a sua origem, e, no caso da heteroplasmia ser confirmada, quais as possíveis consequências produzidas pela presença desse estado / The mitochondrial DNA sequences (mtDNA) have been widely applied as molecular markers in the investigation of genetic diversity and evolution. Despite its undeniable importance, the use of these sequences as molecular markers may present some drawbacks. Heteroplasmy, for example, is recognized as a challenge. This state occurs when an individual has different mitochondrial haplotypes. In a previous work, evidences suggesting the presence of heteroplasmy in the bumblebee Bombus morio were verified. The present work investigated in more detail the presence of heteroplasmy in this species, as well as factors that may influence the identification of this state. The results confirmed the existence of heteroplasmy in this species, and identified that some heteroplasmic haplotypes were shared between individuals from different locations. These shared heteroplasmic haplotypes suggest the existence of stable heteroplasmy in B. morio, which may interfere in evolutionary inferences, especially in population studies. NUMTs, nuclear pseudogenes resulting from the transfer of mtDNA sequences to the nuclear genome, were also detected. These NUMTs showed great sequence divergence from mitochondrial haplotypes, which could affect phylogenetic and population analyzes, as well as species identification through DNA barcoding. In addition, it was observed that amplification errors might be misinterpreted as mtDNA intraindividual variation and overestimates the number of intraindividual haplotypes, especially when low fidelity polymerases are used. Finally, the results observed in this study suggest that the use of mtDNA sequences should be used carefully, and evidences of heteroplasmy, such as the presence of double peaks, should not be ignored. Additional investigations should be applied in case of heteroplasmy evidences to ascertain your source and the consequences of the presence of this state
187

Identificação de Amaranthus palmeri, caracterização da resistência múltipla a herbicidas inibidores da ALS e da EPSPS e controle químico baseado no uso das novas tecnologias transgênicas / Identification of Amaranthus palmeri, characterization of multiple-resistance to ALS and EPSPS inhibitors herbicides and chemical control based on the use of genetically modified herbicide-tolerant crops technologies

Ednaldo Alexandre Borgato 28 February 2018 (has links)
A planta daninha Amaranthus palmeri é nativa dos Estados Unidos, porém foi pela primeira vez relatada no Brasil no ano de 2015. Embora comprovadamente com resistência múltipla aos herbicidas inibidores da ALS e da EPSPS, até o momento não foram investigadas as bases moleculares da resistência. Além disso, por causa da recente introdução da planta daninha no país, alternativas de manejo com culturas tolerantes a herbicidas necessitam ser estudadas. Sendo assim, os objetivos desse trabalho são de caracterizar a espécie de planta daninha introduzida no país, identificar os mecanismos de resistência aos herbicidas inibidores da ALS e da EPSPS presentes no biótipo, e propor abordagens de manejo em ambientes dos novos eventos transgênicos resistentes a herbicidas. Um bioensaio utilizando marcadores genéticos foi desenvolvido para confirmar que a população coletada no estado do Mato Grosso (BR-R) é A. palmeri, e não A. tuberculatus, outra espécie dióica do gênero Amaranthus. Os resultados de experimentos de curvas de dose-resposta e acúmulo de chiquimato indicaram que a BR-R possui alto nível de resistência, com DL50 de 4.426 e 3.400 g glyphosate ha-1 no primeiro e segundo experimento, respectivamente, mais que o dobro da dose típicamente recomendada para o controle da espécie e, adicionalmente, observou se acúmulo mínimo de chiquimato a concentração de 1 mM nos tecidos das plantas tratadas com o herbicida. BR-R também foi resistente a herbicidas dos grupos químicos das sulfoniluréias e imidazolinonas. O mecanismo de resistência ao glyphosate encontrado nesta população foi a super expressão gência, através do aumento no número de cópias do gene da EPSPS no genoma da planta BR-R, entre 50 e 179 cópias adicionais. Além disso, duas substituições de aminoácidos foram observadas na sequência da ALS, W574L e S653N, conferindo resistência tanto a sulfoniluréias quanto a imidazolinonas. No experimento utilizandos os herbicidas correspondentes às culturas geneticamente modificadas com novos traits de tolerância a herbicidas observou se, de uma forma geral, que as associações de herbicidas apresentaram níveis de controle mais satisfatórios. Assim, esta pesquisa confirma a introdução de da espécie A. palmeri no Brasil, assim como a resistência múltipla aos herbicidas inibidores da EPSPS e da ALS. Seu manejo é mais eficaz através da associação de herbicidas, garantindo assim o uso racional das novas tecnologias de culturas geneticamente modificadas com tolerância a herbicidas. / Palmer Amaranth (Amaranthus palmeri) is a weed species native to the United States, but it was reported in Brazil for the first time in 2015. Despite this population being resistant to EPSPS and ALS inhibitors, the molecular basis of its multiple resistance is unknown up to date. Because of this species introduction to Brazil, alternatives of management with the new herbicide-tolerant crops technologies need to be studied. The objectives of this research are to characterize the weed species introduced to Brazil, identify the mechanisms conferring resistance to ALS and EPSPS inhibitors herbicides, and to propose management approaches in environments with the new genetically modified herbicide-tolerant crops. A genotyping bioassay using genetic markers was developed to confirm that the species collected in the state of Mato Grosso (BR-R) is indeed A. palmeri and not A. tuberculatus, another dioceous species in the Amaranthus genus. Dose-response experiments and shikimate accumulation bioassay data indicate high level of resistance, with LD50 of 4,426 and 3,400 g glyphosate ha-1 in the first and second experiments, respectively, higher than the double rate tipically recommended to control it, and minimal accumulation in BR-R with 1 mM of glyphosate in treated plants in the leaf disks assay. BR-R also was resistanto to sulfonilurea and imidazolinone herbicides. The mechanism conferring resistance to glyphosate identified in this population was gene amplification, with increased EPSPS copy number - between 50 and 179 more copies in BR-R. Besides, two target-site mutations were identified in the ALS gene sequencing, W574L and S653N, conferring resistance to sulfonilureas and imidazolinones. The weed control experiment, overal, herbicide tank mixtures achieved higher levels of control. Therefore, this research confirms the introduction of A. palmeri to Brazil, as well as its multiple resistance to EPSPS and ALS inhibitor herbicides. Its control is more efficient with herbicide mixtures, which guarantees more susteinable use of the new herbicide-tolerant crop technologies.
188

Aplicação de marcadores microssatélites de Sus scrofa domestica na caracterização genética de populações de Sus scrofa sp (porco-monteiro) e Tayassu pecari (queixada) / Application of marking microssatélites of Sus scrofa domesticates in the genetic characterization of populations of Sus scrofa sp (Porco-Monteiro) and Tayassu pecari (jaw)

Gonela, Adriana 16 October 2003 (has links)
Os microssatélites ou SSR (Simple Sequence Repeat) por serem considerados os marcadores moleculares ideais, têm se tornado o suporte principal nas análises genômicas em diferentes organismos. Neste estudo, as freqüências alélicas de seis locos microssatélites desenvolvidos para Sus scrofa domestica (ACTG2, ALOX12A, CGA, IGF1, SW444 e TNFB) foram estimadas em duas espécies de Suiformes, Sus scrofa sp e Tayassu pecari. Foi utilizada uma amostra representativa de 99 indivíduos (85% de T. pecari e 15% de S. scrofa sp). Os marcadores foram altamente variáveis, mostrando entre 4 e 15 alelos. A heterozigose observada variou de 0,13 a 1,00 e o conteúdo de polimorfismo informativo de 0,18 a 0,84. Estes resultados indicaram a conservação entre as espécies de suínos e demonstraram a viabilidade da utilização de iniciadores desenvolvidos para S. s. domestica na análise de outras espécies de Suiformes. / Microsatellites have been considered a superior class of genetic markers over earlier ones and became the most useful for genomic population analysis in a great variety of organisms. In this paper we had estimated genetic frequencies of six STRs (ACTG2, ALOX12A, CGA, IGF1, SW444 and TNFB) developed for Sus scrofa domestica that were used to amplify markers in two natural populations of a neotropical feral Suidae (Sus scrofa sp) and a neotropical species of peccary (Tayassu pecari). High degree of polymorphisms was observed and the number of alleles varied from 4 to 15 for the six analyzed loci. The observed heterozygosity was between 0.13 to 1.00 and PIC values varied from 0.18 to 0.84. The study also showed that these markers are evolutionary conserved, allowing the possibility of heterologous amplification.
189

Hearing Aids and the Use of Everyday Sound

Fagelson, Marc A. 24 September 2005 (has links)
No description available.
190

Comparison of Intracanial and Traditional CROS Fittings

Blevins, Jennifer, Noe, Colleen, Fagelson, Marc A., Murnane, Owen D. 01 April 2000 (has links)
No description available.

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