• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 922
  • 453
  • 96
  • 76
  • 74
  • 32
  • 24
  • 21
  • 21
  • 20
  • 19
  • 19
  • 19
  • 19
  • 19
  • Tagged with
  • 2082
  • 417
  • 273
  • 264
  • 247
  • 223
  • 208
  • 164
  • 151
  • 135
  • 131
  • 123
  • 120
  • 109
  • 106
  • 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.
561

Zavedení buněčného modelu pro ovlivnění NFkappa-B faktoru / Introduction of cellular NFkappa-B model

Čečrle, Michal January 2018 (has links)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Michal Čečrle Supervisor: Prof. PharmDr. Petr Pávek, Ph.D. Title of diploma thesis: Introduction of cellular NF-κB model NF-κB is the most important transcription factor involved in cell signaling of inflammatory processes. It participates in the inflammatory reaction in the distinct compartments of the living organism. As a transcription factor, it controls the gene expression of many genes, especially cytokines (tumor necrosis factor alfa, interleukins: IL-1β, IL-2, IL-6, IL-12; chemokines etc.). NF-κB is also a key factor in the activation of monocytes and macrophages In this diploma thesis I focused on the role of NF-κB in the monocyte cell line THP-1. This line is an important model of human macrophages in which the THP-1 line can be differentiated. Using available literature, I summarized all the available knowledge on this issue. At the same time, I conducted several experiments on NF-κB activation in the THP- 1 line as a potential model in the research and development of therapeutic intervention in NF-κB signaling to suppress inflammation.
562

MENDELIZING QUANTITATIVE TRAIT LOCI THAT UNDERLIE RESISTANCE TO SOYBEAN SUDDEN DEATH SYNDROME

Lee, Yi-Chen 01 August 2016 (has links)
Soybean (Glycine max [L.] Merr.) cultivars differ in their resistance to sudden death syndrome (SDS). The syndrome is caused by root colonization by Fusarium virguliforme (ex. F. solani f. sp. glycines). Breeding for improve SDS response has proven challenging, possible due to interactions among the 18 known loci for resistance. Four loci for resistance to SDS (cqRfs to cqRfs3) were found clustered within 20 cM of the rhg1 locus underlying resistance to soybean cyst nematode (SCN) on chromosome 18. Another locus on chromosome 20 (cqRfs5) was reported to interact with this cluster. The aims of this study were to compare the inheritance of resistance to SDS in a near isogenic line (NIL) population that was fixed for resistance to SCN but still segregated at 2 of the 4 loci (cqRfs1 and cqRfs) for resistance to SDS on chromosome 18; to examine the interaction with the locus on chromosome 20; and to identify candidate regions underlying quantitative trait loci (QTL). Used were a near isogenic line population derived from residual heterozygosity in an F5:7 recombinant inbred line EF60 1-40; SDS response data from 2 locations and years; four microsatellite markers and six thousand SNP markers. Polymorphic regions were found from 2,788 to 8,938 Kbp on chromosome 18 and 33,100 to 34,943 Kbp on chromosome 20. Both regions were significantly (0.005 < P > 0.0001) associated with resistance to SDS. A fine map was constructed that Mendelized the three loci. Substitution maps suggested the two loci on chromosome 18 were actually 3 loci (cqRfs, cqRfs1 and cqRfs19). Candidate genes for cqRfs19 were identified in a small region of the genome sequence of soybean. An epistatic interaction was inferred where the allele of loci on chromosome 18 determined the value of the locus on chromosome 20. It was concluded that SDS loci are both complex and interacting which may explain the slow progress in breeding for resistance to SDS.
563

Vyhodnocení vlivu potenciálně vybudovaných protierozních opatření pomocí modelování v GIS / GIS modeling of impact of the potential anti-erosion measures

MACHO, Bohumil January 2018 (has links)
Erosion is phenomenon, which continues to expand around the world and it is important to reduce its negative effects on both agricultural and non-agricultural lands. This thesis assesses impacts of anti-erosion measures of organizational, agrotechnical, technical character and their combinations modeled in GIS. The effects of four model crop rotation methods are compared here in combination with different variants of agro-technical measures. Then in the most critical lands have been compared the influences of the most apprepiate individual proceeding. Literature review introduces the reader to the problems of water erosion, modeling and solving anti-erosion protection.
564

Modelagem numérica do terreno na avaliação do volume admissível em canais de cordões de contorno nivelados

Gomes, Luciano Nardini [UNESP] 16 December 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:32:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-12-16Bitstream added on 2014-06-13T21:04:34Z : No. of bitstreams: 1 gomes_ln_dr_botfca.pdf: 919435 bytes, checksum: 21a680807df6222aa5f0029cc1b06f57 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / A ação de processos erosivos em áreas rurais constitui um dos principais problemas da agricultura mundial. A falta de ações conservacionistas nessas áreas, somadas às ações de intemperismo proporciona perda considerável de solos agricultáveis, prejuízo ambiental que é acrescido pela poluição e assoreamento dos rios. Na tentativa de potencializar a produção de alimentos e visando atender à demanda proporcionada pelo crescente aumento da população, técnicas como o cultivo mínimo e o plantio direto contribuem para que haja equilíbrio entre produção agrícola e o meio ambiente, interesse patente das gerações presente e futura. Contudo, notadamente em pequenas propriedades rurais, é comum ainda o uso de tecnologias convencionais, como implantação de cordões de contorno. Em pequena propriedade rural, em área de reforma de pastagem, foram locados quatro cordões de contorno utilizando trator e arado convencional. Com estação total foram realizados dois levantamentos planialtimétricos, logo após a construção dos cordões de contorno e decorridos doze meses. Os dados foram processados pelos softwares DataGEOSIS e LandDESKTOP, onde foram criados artifícios para o cálculo do volume admissível nos canais dos cordões de contorno nas duas épocas distintas com o objetivo de verificar a validade da modelagem numérica do terreno na caracterização da movimentação de solo nos canais. Com base na metodologia adotada foi possível concluir que o modelo numérico do terreno permitiu avaliar o volume de solo movimentado nas três feições de relevo estudadas (relevo natural à montante, fundo do canal e camalhão), quando se constatou que a diminuição da capacidade de acúmulo de águas pluviais nos cordões de contorno foi em média 20,76% em um ano. / The actions of the erosive process in rural areas constitutes one of the most serious problem in agriculture worldwide. The lack of conservationist actions in those areas added to the weathering actions led to a preoccupying agricultural soil loss, environmental damage increased by pollution and rivers sedimentation. To attempt to increase the food production and aiming to help the food demand due to the population increasing, techniques like minimum tillage and no tillage contribute to the equilibrium between agricultural production and environment, what is the interest of the current and future generations. However, mainly in small farms it is common the use of conventional techniques like the contour lines implantation. In an area of pasture reformation into a small farm, four contour lines were demarcated using a tractor and conventional plow. Using a total station were made two topographic survey just after the contour lines demarcation and after twelve months. The data were processed using the software DataGEOSIS and LandDESKTOP, where artifices were created to the calculation of the possible water volume into channels of contour lines for the two dates of surveying, aiming to verify the validity of numerical terrain model to the soil movement characterization into channels. Considering the methodology used was possible to conclude that the numerical terrain model allowed to evaluate the soil volume alteration in the three relief forms studied (natural relief above, channel bottom and soil ridge), when was verified that the water storage capacity into contour lines decreased in average 20,76 % in a year.
565

Probing galaxy evolution with quasar absorption lines

Berg, Trystyn Andrew Munro 05 July 2018 (has links)
When we look throughout the Universe, we can see the stages of galaxy evolution across cosmic time; however there are still many unanswered questions about the details of galaxy evolution. How did galaxies like our Milky Way assemble? Do the first galaxies look different than our own? What makes galaxies stop forming stars? Many of these questions can be addressed by studying the detailed chemistry of gas located in and around galaxies. Absorption lines imprinted on quasar spectra probe this hard-to-see gas within and surrounding galaxies, giving an luminosity-unbiased census of gas from z~0 to the epoch of the most distant quasars. In this thesis, I present two samples of high resolution spectra of quasars obtained from both ground- and space-based observatories to study the evolution of galaxies through their gas-phase absorption lines. The first of the two samples presented in this thesis consists of the 100 quasar sightlines from the XQ-100 legacy survey completed with the X-Shooter spectrograph on the Very Large Telescope in Chile. The XQ-100 survey provides a blind sample of over 350 HI absorption line systems associated with galaxies with column densities 18.8<=logN(HI)<=21.5. Using this sample, I investigated the evolution of neutral gas reservoirs from z~4.5 to z~2.0. I demonstrate that the lower column density sub-damped Lyman alpha systems (with column densities 19.0<=logN(HI)<20.3) contribute ~20% of the HI observed in galaxy gas reservoirs compared to the rarer but high column density damped Lyman alpha systems (DLAs; logN(HI)>=20.3). Furthermore, I show that using the presence of metal lines (particularly MgII absorption) to identify and select absorbing systems can potentially bias the properties of the sample; absorbers selected to contain strong metal line absorbers tend to exclude low metallicity and low HI column density systems. I demonstrate that the systems missed by metal-selected searches can have a significant impact on the study of the cosmic evolution of neutral gas reservoirs. In addition to the HI content, the metal abundances for 13 elements in the 41 DLAs of the XQ-100 sample are presented. In concert with my literature compilation of 280 DLA metal abundance measurements, I studied the dust-corrected [Zn/Fe]. This work emphasizes that near-IR coverage of X-Shooter provides unprecedented access to MgII, CaII and TiII lines (at redshifts 3-4) to provide additional evidence for subsolar [Zn/Fe] ratio in DLAs, a chemical signature that DLAs can be high-redshift dwarf galaxy analogues. Furthermore, the XQ-100 DLA sample consists of several unique systems that probe the effects of environment on the chemical evolution of the Universe, as well as the chemical makeup of the first generations of stars. I demonstrate that DLAs close to their background quasar (within 5000 km/s) with logN(HI)<21.0 show lower [S/H] and [Fe/H] (relative to intervening systems with similar redshift and N(HI)), whilst higher [S/H] and [Si/H] are seen in these proximate systems with logN(HI)>21.0. Contrary to previous studies, DLAs within 10,000 km/s of another DLA show no difference in [alpha/Fe] relative to single DLAs matched in metallicity and redshift. In addition, I present follow-up high-resolution data of J0034+1639, a sightline containing three DLAs, including a metal-poor DLA with [Fe/H]=-2.82 (the third lowest [Fe/H] in DLAs identified to date) at z=4.25. In the latter part of this thesis, I study the circumgalactic medium (CGM) of galaxies that host an active galactic nucleus (AGN). AGN are thought to play a critical role in shaping galaxies, but their effect on the gaseous reservoirs surrounding galaxies is not well studied. I present results from the COS-AGN survey: 19 quasar sightlines that probe the gas surrounding 20 optically-selected AGN host galaxies observed over 65 hours with the Hubble Space Telescope. Absorption lines from a variety of species are measured and compared to a stellar mass and impact parameter matched sample of sightlines through non-AGN galaxies. Amongst the observed species in the COS-AGN sample (HI, CII, SiII, SiIII, CIV, SiIV, NV), only HI shows a high covering fraction whilst many of the metal ions are not detected in individual sightlines. A sightline-by-sightline comparison between COS-AGN and the control sample yields no significant difference in equivalent width distribution. However, stacked spectra of the COS-AGN and control samples show significant enhancements in the equivalent width of both Lya and SiIII at high impact parameters (>164 kpc) by a factor of +0.45+/-0.05 dex and >+0.75 dex respectively. The lack of detections of both high-ionization species near the AGN and strong kinematic offsets between the absorption systemic galaxy redshifts indicates that neither the AGN's ionization nor its outflows are the origin of these differences. Instead, I suggest the observed differences could result from either AGN hosts residing in haloes with intrinsically distinct gas properties, or that their CGM has been affected by a previous event, such as a starburst, which may also have fuelled the nuclear activity. / Graduate
566

Representação de linhas de transmissão, utilizando elementos discretos de circuitos, no domínio das fases

Silva, Rodrigo Cleber da [UNESP] 02 March 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-03-02Bitstream added on 2014-06-13T18:07:16Z : No. of bitstreams: 1 silva_rc_me_ilha.pdf: 1094479 bytes, checksum: 97b67533f29314983c7862339e30e9e6 (MD5) / PROPG - Programa de Pós-Graduação / Neste trabalho será mostrado o desenvolvimento de dois modelos de linhas de transmissão, baseados em elementos discretos de circuitos, que fornecem respostas diretamente no domínio do tempo e nas fases. Os dois modelos propostos partem da hipótese de que um pequeno segmento de linha de transmissão pode ser representado por um circuito . Hipótese esta já validada para linhas monofásicas por diversos autores, e que neste trabalho será utilizada para representar pequenos segmentos de linhas bifásicas e trifásicas. Deste modo, tais linhas serão representadas por uma grande quantidade de blocos (constituídos de elementos discretos de circuitos que representam um pequeno segmento de linha) conectados em cascata. No primeiro modelo proposto, válido para representar linhas idealmente transpostas, as fases de cada um dos pequenos segmentos de linha são separados em seus modos de propagação, e as correntes e tensões são calculadas no domínio modal. No entanto a conversão fase-modo-fase está inserida nas equações de estado que descrevem as correntes e tensões ao longo da linha, sendo que não há a necessidade do usuário do modelo conhecer a teoria de representação de linhas no domínio modal. Uma vez que o modelo não usa explicitamente o processo de decomposição modal, neste trabalho o mesmo será considerado como sendo um modelo desenvolvido no domínio das fases sem o uso explícito da teoria de decomposição modal. Este modelo pode ser utilizado para representar linhas que podem ter suas fases desacopladas por matrizes reais e invariáveis em relação à frequência. A representação de pequenos segmentos de linhas por elementos discretos de circuitos também foi aplicada em linhas bifásicas e trifásicas sem plano de simetria vertical. Neste caso, devido ao fato de que as matrizes... / This paper will show the development of two models of transmission lines, based on discrete circuit elements, which provide answers directly in the time domain and phase. The two proposed models start from the assumption that a small segment of transmission line can be represented by a -circuit, this hypothesis has already been validated for single-phase by several authors and this work will be used to represent small segments of lines biphasic and triphasic. Thus, these lines will be represented by a large number of blocks (consisting of discrete circuit elements that represent a small segment of the line) in cascade. In the first model, valid for ideally transposed lines represent the phases of each small line segments are separated into their modes of propagation and the currents and voltages are calculated in the modal domain. However the conversion phase-mode-phase is inserted into the state equations describing the currents and voltages along the line being that there is no need for the user the model to know representation theory of modal lines. Since the model does not explicitly use modal decomposition process, this paper it will be considered to be a model developed in the field of the phases without the explicit use of modal decomposition theory. This model can be used to represent lines that may have decoupled phases for real matrices and invariant with respect to frequency. The representation of small line segments by discrete circuit elements has also been applied in biphasic and triphasic lines without vertical symmetry plane. In this case, due to the fact that the matrices that separate line in their modes of propagation are not real and invariant with respect to frequency, the model was developed directly in the field of the phases without the use of modal decomposition matrices
567

Estudo da estabilidade do método das linhas usando a dinâmica de um cabo flexível /

Colnago, Marilaine. January 2012 (has links)
Orientador: Messias Meneguette Júnior / Banca: Vanessa Avansini Botta Pirani / Banca: Heloisa Helena Marino Silva / Resumo: O estudo de equações diferenciais parciais tem merecido muito destaque nos últimos anos. O fato é que se trata de uma área muito utilizada em vários ramos da Ciência como Matemática, Física e Engenharia. Além disso, permite a modelagem de muitos problemas encontrados em nosso cotidiano e na natureza em geral. Porém, a sua utilização se torna complicada uma vez que, tais equações nem sempre apresentam o que chamamos de solução analítica. Isto só acontece com uma "pequena" classe de equações (ver [19]). Fazse então necessário, buscar outras alternativas para a resolução de tais equações e daí os métodos numéricos de resolução desempenham um papel muito importante. O método das linhas, conhecido como um método de semi-discretização, representa uma alternativa para encontrar tais soluções e tem recebido atenção na atualidade. O presente trabalho, abrange, um estudo do método das linhas em sua forma original, bem como o estudo da estabilidade desse método utilizando a dinâmica de um cabo flexível. O método não foi satisfatório tanto para o cabo inextensível quanto para o cabo extensível, logo após poucos passos no tempo, a solução se deteriorou, representando, ao nosso ver, a instabilidade do método / Abstract: The study of partial differential equations has received much attention in the recent years. The fact is that this is an area widely used in various branches of science such as Mathematics, Physics and Engineering. Furthermore, it allows the modeling of many problems encountered in our activities and nature in general. However, their use becomes complicated since these equations do not always have what we call analytical solution. This only happens with a " small" class of equations (see [19]). So, it is necessary to seek other alternatives for solving these equations, hence the numerical resolution methods play an important role. The method of lines, known as a semi-discretization method, represents an alternative to find such solutions and has received attention in the literature. This work includes a study of the method of lines in its original form, as well as to study the stability of this method using the dynamics of a flexible cable. This method was not satisfactory for both the inextensible cable and to extensible cable, after a few steps in time, the solution has deteriorated, representing, in our view, the instability of the method / Mestre
568

Impactos ambientais decorrentes de vazamento de gás natural de baixa e média pressões, na área urbana central do município de São Paulo /

Moscardi, Jean Prost. January 2005 (has links)
Orientador: Antonio Roberto Saad / Banca: José Eduardo Zaine / Banca: José Luiz Albuquerque Filho / Resumo: Com o crescente desenvolvimento do mercado de gás o Brasil e, conseqüente, mudança da matriz energética do país, iniciou-se a procura por tecnologias as quais atenderiam as novas demandas. A área de Meio Ambiente, cada vez mais, está sendo direcionada como ponto-chave enquanto condicionante na realização ou não de qualquer evento. O trabalho aborda de maneira sucinta, as interações existentes entre empreendimento, tubulações de gás apresentando baixas e médias pressões; e, a área de atuação e apresentou uma proposição para um possível impacto ambiental. Apresenta linha de pesquisa desenvolvida pela agência reguladora competente (COMPANIA DE TECNOLOGIA DE SANEAMENTO AMBIENTAL, CETESB) que atua neste campo e tangencia os mais diversos aspectos correlacionados (danos diretos, indiretos e outros). Ao todo, o levantamento ocorreu em 40 locais situados no centro da Cidade de São Paulo e foram constatadas alterações nos três segmentos do ambiental: físico-químico, biótico e antrópico. Em suas conclusões, são propostas as possíveis causas dos danos e medidas mitigadoras a este impacto. / Abstract: With the increasing development of the market of gas in Brasil, and so, change of the energy matrix of the country, it was initiated looks it for technologies which would take care of the new demands. The area of Environment, each time more, is being directed as point key in the accomplishment or not of any event. The work approached in easy way, the existing interactions between enterprise and area of performance and presented a proposal for a possible Environment impact. It presents line of research developed for the competent regulating agency (CETESB) that it acts in this field and tangent the most diverse correlated aspects (damages right-handers, indirect and others). At all, the research displayed at 40 places on São Paulo's city down town and it was observe alterations at tree environmental spheres: physic-chimistral , biotic and antropic. It considers in its possible conclusions damages and mitigating measures and this impact. / Mestre
569

Implementation of a wideband microstrip phased array antenna for X-band radar applications

Davids, Vernon Pete January 2009 (has links)
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009 / This thesis presents the design, analysis and implementation of an eight-element phased array antenna for wideband X-band applications. The microstrip phased array antenna is designed using eight quasi-Yagi antennas in a linear configuration and is printed on RT/Duroid 6010LM substrate made by Rogers Corporation. The feeding network entails a uniform beamforming network as well as a non-uniform -25 dB Dolph-Tschebyscheff beamforming network, each with and without 45° delay lines, generating a squinted beam 14° from boresight. Antenna parameters such as gain, radiation patterns and impedance bandwidth (BW) are investigated in the single element as well as the array environment. Mutual coupling between the elements in the array is also predicted. The quasi-Yagi radiator employed as radiating element in the array measured an exceptional impedance bandwidth (BW) of 50% for a S11 < -10 dB from 6 GHz to 14 GHz, with 3 dB to 5 dB of absolute gain in the frequency range from 8 GHz to 11.5 GHz. The uniform broadside array measured an impedance BW of 20% over the frequency band and a gain between 9 dB to 11 dB, whereas the non-uniform broadside array measured a gain of 9 dB to 11 dB and an impedance BW of 14.5%. Radiation patterns are stable across the X-band. Beam scanning is illustrated in the E-plane for the uniform array as well as for the non-uniform array.
570

Modelagem numérica do terreno na avaliação do volume admissível em canais de cordões de contorno nivelados /

Gomes, Luciano Nardini, 1979- January 2009 (has links)
Resumo: A ação de processos erosivos em áreas rurais constitui um dos principais problemas da agricultura mundial. A falta de ações conservacionistas nessas áreas, somadas às ações de intemperismo proporciona perda considerável de solos agricultáveis, prejuízo ambiental que é acrescido pela poluição e assoreamento dos rios. Na tentativa de potencializar a produção de alimentos e visando atender à demanda proporcionada pelo crescente aumento da população, técnicas como o cultivo mínimo e o plantio direto contribuem para que haja equilíbrio entre produção agrícola e o meio ambiente, interesse patente das gerações presente e futura. Contudo, notadamente em pequenas propriedades rurais, é comum ainda o uso de tecnologias convencionais, como implantação de cordões de contorno. Em pequena propriedade rural, em área de reforma de pastagem, foram locados quatro cordões de contorno utilizando trator e arado convencional. Com estação total foram realizados dois levantamentos planialtimétricos, logo após a construção dos cordões de contorno e decorridos doze meses. Os dados foram processados pelos softwares DataGEOSIS e LandDESKTOP, onde foram criados artifícios para o cálculo do volume admissível nos canais dos cordões de contorno nas duas épocas distintas com o objetivo de verificar a validade da modelagem numérica do terreno na caracterização da movimentação de solo nos canais. Com base na metodologia adotada foi possível concluir que o modelo numérico do terreno permitiu avaliar o volume de solo movimentado nas três feições de relevo estudadas (relevo natural à montante, fundo do canal e camalhão), quando se constatou que a diminuição da capacidade de acúmulo de águas pluviais nos cordões de contorno foi em média 20,76% em um ano. / Abstract : The actions of the erosive process in rural areas constitutes one of the most serious problem in agriculture worldwide. The lack of conservationist actions in those areas added to the weathering actions led to a preoccupying agricultural soil loss, environmental damage increased by pollution and rivers sedimentation. To attempt to increase the food production and aiming to help the food demand due to the population increasing, techniques like minimum tillage and no tillage contribute to the equilibrium between agricultural production and environment, what is the interest of the current and future generations. However, mainly in small farms it is common the use of conventional techniques like the contour lines implantation. In an area of pasture reformation into a small farm, four contour lines were demarcated using a tractor and conventional plow. Using a total station were made two topographic survey just after the contour lines demarcation and after twelve months. The data were processed using the software DataGEOSIS and LandDESKTOP, where artifices were created to the calculation of the possible water volume into channels of contour lines for the two dates of surveying, aiming to verify the validity of numerical terrain model to the soil movement characterization into channels. Considering the methodology used was possible to conclude that the numerical terrain model allowed to evaluate the soil volume alteration in the three relief forms studied (natural relief above, channel bottom and soil ridge), when was verified that the water storage capacity into contour lines decreased in average 20,76 % in a year. / Orientador: Lincoln Gehring Cardoso / Coorientador: João Carlos da Costa Catalão Fernandes / Banca: Zacarias Xavier de Barros / Banca: Vilmar Antonio Rodrigues / Banca: Sérgio Pascola de Campos / Banca: Fernanda Leite Ribeiro / Doutor

Page generated in 0.0219 seconds