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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.
51

Método de difusão radial: validação e otimização do processo de extração para doseamento de taninos de espécies medicinais da caatinga

SANTOS, Luma Gomes dos 17 May 2012 (has links)
Submitted by Heitor Rapela Medeiros (heitor.rapela@ufpe.br) on 2015-03-04T12:36:58Z No. of bitstreams: 2 Dissertação_Luma_Gomes_dos_Santos.pdf: 1082463 bytes, checksum: a18a4596e37a6a3db1dc12c768bbd13e (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-04T12:36:58Z (GMT). No. of bitstreams: 2 Dissertação_Luma_Gomes_dos_Santos.pdf: 1082463 bytes, checksum: a18a4596e37a6a3db1dc12c768bbd13e (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2012-05-17 / CAPES / As plantas sempre foram utilizadas por suas propriedades terapêuticas observadas empiricamente através das gerações. Atualmente, sabe-se que essas propriedades são devidas a presença de metabolitos secundários, e isso tem despertado o interesse de pesquisadores que visam os vegetais como fonte promissora de novas moléculas úteis ao homem para o tratamento de uma ampla gama de doenças. Há uma grande variedade de metabólitos secundários, com diferentes estruturas químicas e diversas funções, dentre estes estão os taninos. Diversos tipos de ensaio têm sido utilizados para a quantificação de taninos. Os métodos mais apropriados para determinação de taninos são os ensaios com precipitação de proteínas, porem outros métodos também são utilizados, sendo os mais comuns os métodos de precipitação de metais e métodos colorimétricos. Apesar de serem amplamente utilizados para análise quantitativa de taninos de maneira geral, os métodos colorimétricos são específicos para algumas classes de taninos. A metodologia de doseamento desenvolvida por Hagerman tem como base a propriedade que os taninos possuem de se complexar com macromoléculas, neste caso, as proteínas. É bastante simples, rápida e econômica, muito útil em estudos que envolvem uma grande quantidade de amostras. Entretanto tem se mostrado um método pouco sensível uma vez que se utiliza uma grande quantidade de massa vegetal para extração. Este trabalho teve como objetivo realizar a otimização do processo de extração para doseamento de taninos através da difusão radial e realizar o estudo de validação do método. Para otimização da extração algumas variantes ao método original foram testadas, são elas: massa vegetal, solventes, tipo e tempo de extração. Observou-se que a redução da massa vegetal a metade pouco influenciou no valor final do teor de taninos da espécie testada, uma melhora significativa dos resultados quando da utilização de acetona 50% (v/v) em relação ao solvente original metanol 50% (v/v). Resposta positiva foi também obervada com a utilização de aparelho de ultrassom que aumentou consideravelmente o diâmetro do disco reduzindo a metade o tempo necessário para uma extração eficiente. Para o ensaio de validação todos os parâmetros obrigatórios foram avaliados. O método foi considerado linear e com alta sensibilidade de quantificação (27,72 μg/poço). Mostrou-se também robusto e com recuperação aceitável (85,96%). Os resultados obtidos para repetitividade (intra-corrida) e precisão intermediária (inter-corridas), certificaram a precisão do método, obtendo-se valores entre 1,89 e 7,03%. Para a exatidão valores entre 100,47 e 105,26% foram obtidos, que se encontra dentro dos limites preconizados pela ANVISA. Sendo assim o método foi considerado preciso, exato e reprodutível, além de ser de fácil execução e baixo custo.
52

“It’s My Life ” Historias de una radio llamada Rock & Pop

Novoa Valdebenito, Rocio Ester 12 1900 (has links)
Memoria para optar al título de Periodista / El autor no autoriza el acceso a texto completo de su documento / ¿Cómo fue que supe de la radio? Fue de las últimas cosas que pensé antes de querer dormir. Pero no podía. Estoy con un pie adentro y uno afuera de la radio Rock & Pop y se me parte el corazón. Aunque no debería. Porque es un trabajo, porque lo importante está afuera... Sí. Afuera de esta cama, y afuera de la oficina. Y fuera de cualquier entendimiento. Una tarde Carlos –Costas, mi ex jefe hace algunos meses, hoy flamante director de Radio ADN– dijo que reconocía en mí sus "mismos niveles de pasión y desquicio con la radio". Ahí mismo me quise poner a llorar. En una cocina chica, mientras escuchaba que Jean-Philippe –Cretton, el conductor del programa que produzco en la radio– decía que Jorge González volvía a caer en la clínica tras el accidente cerebelo-vascular que lo había dejado fuera de los escenarios. No sabía qué pesaba más, si la emoción profunda de que lo más parecido a un hermano mayor, el tipo que me ofreció la pega soñada y apostó por mí hasta que tuvo que irse a dirigir una de las radios más importantes del país, se vea reflejado en mí; o la pena de saber que uno de los hombres más inspiradores e influyentes de mi vida estuviera grave en una clínica. Tampoco sabía cuán inmaduro era el hecho de que ambas cosas lograran congelarme en un momento en el que había que tener la mente fría y supervisar una puesta al aire impecable... 4 Todo esto estaba pasando en la radio, un lugar donde suele regir más corazón que otras cosas, al menos en los que nos tomamos esto en una dimensión mucho más que de trabajo.
53

Interactions Between Dopamine Neurons and Radial Glial Cells In the Adult Goldfish Forebrain

Xing, Lei January 2016 (has links)
Aromatase is the only enzyme that converts androgens into estrogens, which is found in the brain, testes and ovaries. In teleosts, brain aromatase is exclusively expressed in radial glial cells, which are the abundant stem-like non-neuronal progenitors involved in neuroendocrine functions and neurogenesis in the central nervous system. With little information about radial glial cell regulation by neurotransmitters and neurohormones available, the overall goal of this thesis is to investigate the interactions between dopamine neurons and radial glial cells in the adult goldfish (Carassius auratus) forebrain. Immunocytochemistry and confocal imaging revealed a close anatomical relationship between dopamine neurons and radial glial cells along the ventricular surface in the telencephalon. Transcriptional regulation of brain aromatase by dopamine indicated a brain region-specific pattern and suggested the involvement of other regulators in the goldfish forebrain. A novel goldfish primary radial glial cell culture model was established and characterized for brain aromatase regulation studies. Pharmacological studies demonstrated that specific activation of dopamine D1 receptors up-regulates brain aromatase through a cAMP-dependent molecular mechanism, which can be enhanced or attenuated by the product of aromatase action, 17β-estradiol. Proteome profiling and the response following treatment with the specific dopamine D1 receptor agonist SKF 38393 revealed that proteins involved in cell proliferation and growth are regulated through small molecules- and transcription factors-mediated signaling pathways. Analysis of genes related to radial glial cell and dopamine neuron functions demonstrated that glial activation and dopamine neuron recovery are estrogen-dependent in a neurotoxin MPTP-induced goldfish model of Parkinson’s disease. This thesis illustrates novel molecular mechanisms underlying brain aromatase regulation as well as radial glial cell function regulation and provides a framework for future investigation of existing endocrine disruptors modulating neurosteroid levels in the teleost brain.
54

Vypracování a konstrukční realizace návrhu odstředivého ventilátoru s proměnnou geometrií lopatkového kola z lehké konstrukce / Erarbeitung und konstruktive Umsetzung eines Konzeptes zur Realisierung eines Radialventilators mit variabler Schaufelradgeometrie in Leichtbauweise

Trentin, Tomáš January 2021 (has links)
This thesis deals with the development and design of a mechanism used to change the geometry of impeller blades in radial fans. Firstly, a suitable design was selected and then constructed taking into account the forces and loads applied. The blade consists of two parts - fixed, and movable. The movable part extends or retracts behind the fixed part of the blade, changing its length and therefore the operating characteristics of the fan. The simulation part of the work deals with the effect of the changed blade geometry on the fan performance at one particular operating point. The results show a slight reduction in performance, but on the other hand the fan is operable under a wider range of operating conditions. The conclusion of the paper suggests the need for further research to gain a deeper understanding of the capabilities of radial control mechanism fans.
55

Generating a proteomic profile of neurogenesis, through the use of human foetal neural stem cells

Garnett, Shaun 18 February 2020 (has links)
Introduction Neurogenesis, the development of new neurons, starts soon after the formation of the neural tube and is largely completed by birth. Development of the brain after birth is mainly reliant on the formation of new connections between surviving neurons. However, adult neurogenesis does continue in the subgranular zone of the hippocampus from quiescent adult neural stem cells. Traditionally neural stem cells were cultured as neurospheres, a heterogeneous agglomeration of neural cells at various stages of differentiation. This heterogeneity prevented accurate quantitative analysis. In 2008 Sun et al produced the first non-immortalised human foetal neural stem (NS) cell line from nine week old human foetal cortex. These cells are cultured as monolayers, have a radial glia like appearance, self renew and form all three neural cell types, neurons, astrocytes and oligodendrocytes upon differentiation. More recently human foetal neuroepithelial like (NES) stem cells have been produced from five week old human foetal hind-brain, they resemble neuroepithelial cells, with characteristic rosettes, upon differentiation they appear to form a pure population of neurons. These homogeneous monolayer cultures enable quantitative proteomic analysis, to increase our understanding of early brain development Methods Three NES and two NS cell lines were available for analysis. They proliferate by stimulation from FGF and EGF, removal of these growth factors results in spontaneous differentiation. Proliferating NES and NS cells were compared using SILAC labelling. In addition, each cell line was differentiated for 12 days, 6 timepoints were taken and compared using label free quantitation. Results 4677 proteins were quantitated with 473 differentially expressed, revealing fundamental differences between NES and NS cells. NES cells are less differentiated, expressing SOX2 and LIN28, have active cell cycle processes, DNA elongation, histone modification and miRNA mediated gene silencing. Whereas NS cells are more developmentally defined, express multiple membrane proteins, have activated focal adhesion, thereby increasing their binding and interaction with their environment. NS metabolism is more oxidative, utilises lipid metabolism, the pentose phosphate pathway and produces creatine phosphate. Upon differentiation the cell cycle processes are downregulated and neurogenic and gliogenic processes increased. Conclusion This work represent a detailed in vitro characterisation of non immortalised human foetal neural stem cells, it describes the regulatory, metabolic and structural changes occurring within neural stem cells in early brain development. The information herein points towards de-differentiation potentially through LIN28-let7, as a means to produce more neurogenic neural stem cells in vitro thus aiding regenerative therapies, as well as provides a wealth of information for better understanding neurological developmental disorders.
56

Safety and Efficacy of Radial Versus Femoral Access for Rotational Atherectomy: A Systematic Review and Meta-Analysis

Khan, Abdul Ahad, Panchal, Hemang B., Zaidi, Syed Imran M., Papireddy, Muralidhar R., Mukherjee, Debabrata, Cohen, Mauricio G., Banerjee, Subhash, Rao, Sunil V., Pancholy, Samir, Paul, Timir K. 01 March 2019 (has links)
Introduction: Over the recent years, there has been increased interest in the use of transradial (TR) access for percutaneous coronary intervention (PCI), including rotational atherectomy (RA). However, a large proportion of operators seem to be reluctant to use TR access for complex PCI including rotational atherectomy for heavily calcified coronary lesions. Methods: We searched MEDLINE, ClinicalTrials.gov and the Cochrane Library for studies comparing radial versus femoral access in patients undergoing RA. Studies were included if they reported at least one of the following outcomes in each group separately: major adverse cardiac events (MACE), major bleeding, stent thrombosis, myocardial infarction (MI), hospital length of stay, radiation exposure, procedure time, procedure success and all-cause mortality. Odds ratio (OR) or mean difference (MD) with 95% confidence interval (CI) were calculated and a p-value of <0.05 was considered as a level of significance. Results: This meta-analysis included 5 retrospective studies with 3315 patients undergoing RA via radial access and 5838 patients via femoral access. Radial access was associated with lower major access site bleeding (OR: 0.45, 95% CI: 0.31–0.67, p < 0.001), and radiation exposure (MD: −16.1, 95%CI: −25.4–−6.7 Gy cm 2 , p = 0.0007). There were no significant differences observed in all-cause in-hospital mortality (OR: 0.92, 95% CI: 0.69–1.23, p = 0.58); MACE (OR: 0.80, CI: 0.63, 1.02, p = 0.08), stent thrombosis (OR: 0.28, 95%CI: 0.06–1.33 p = 0.11); and MI (OR: 0.43, 95%CI: 0.15–1.24, p = 0.12). There were no significant differences in hospital stay, procedure time or procedure success between the two groups (p > 0.05). Conclusion: This meta-analysis of 9153 patients from observational studies demonstrates similar all-cause mortality, MACE, procedural success and procedural time during RA performed using TR access and TF access. However, TR access was associated with decreased access site bleeding and radiation exposure. Given the observational nature of these findings, a randomized controlled trial is warranted for further evidence.
57

Radial and Axial Designs for Magnetic Absorbent Collector in Water

Renzetti, Andrew John 08 1900 (has links)
The use of collection systems for magnetic sorbents such as Magnetic Activated Carbon are discussed in order to gauge their efficacy in marine environments. Two collectors were built and tested, one which utilized a radial orientation of magnets and another with axially placed magnets. The two systems underwent a series of test with differing linear velocities and angular velocities. From the results, the axial system outperformed its radial counterpart, being most effective with a relatively high concentration of discs placed in series. The medium concentration, however, proved increasingly effective with higher velocities, meaning an optimization concentration exists for this design. The radial system was tested with high and low concentrations of small and large magnets, respectively. The larger magnets, although providing less concentration points in the alternating array, proved more effective for the collection of MAC. From these tests several new innovations were suggested, including belt tensioners, add on mechanisms, and a hybridized design in order to fully optimize the collection of MAC.
58

Positive Radial Solutions for P-Laplacian Singular Boundary Value Problems

Williams, Jahmario 17 August 2013 (has links)
In this dissertation, we study the existence and nonexistence of positive radial solutions for classes of quasilinear elliptic equations and systems in a ball with Dirichlet boundary conditions. Our nonlinearities are asymptotically p-linear at infinity and are allowed to be singular at zero with non-positone structure, which have not been considered in the literature. In the one parameter single equation problem, we are able to show the existence of a positive radial solution with precise lower bound estimate for a certain range of the parameter. We also extend the study to a class of asymptotically p-linear system with two parameters and in the presence of singularities. We establish the existence of a positive solution with a precise lower bound estimate when the product of the parameters is in a certain range. Necessary and sufficient conditions for the existence of a positive solution are also obtained for both the single equation and system under additional assumptions. Our approach is based on the Schauder Fixed Point Theorem.
59

A LABORATORY INVESTIGATION OF THE NEAR-SURFACE VELOCITIES IN TORNADO-LIKE VORTICES

Wayne, Simon Patrick 03 August 2007 (has links)
No description available.
60

Image Processing Algorithms for a Tiled Multi-projection Screen

GUO, DAWEI January 2020 (has links)
Nowadays the development of the screen technology is really fast, there are lcd, led, oled screen and many kinds of screens. They all have their own advantages and disadvantages, LCD screen is usually constrained by the size, and the LED screen is usually constrained by the resolution. In this thesis I will introduce a tiled projection screen which combined LED and LCD together. My major work is to develop algorithms which are used to solve three major problems. The first problem is the radial distortion caused by the lens. This problem is different from the usual distortion correction problem, the method used in this thesis is a reverse process of the camera calibration and the key is to simulate the distortion formula. The second problem is the complex brightness condition of the tiled projected image. In the thesis a non-linear edge blending method is applied so the projected images could merge together seamlessly. The third problem is combination of the LED and the LCD without harming the resolution of the whole picture. The result shows that the size and the resolution have been improved greatly. / Thesis / Master of Applied Science (MASc)

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