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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.
21

Variations in the Ssegment of Rift Valley fever virus with special reference to the nonstructural NSs coding region

Aitken, Susan Claire 04 May 2009 (has links)
Rift Valley fever virus (RVFV) is a Phlebovirus member of the Bunyaviridae family and it is the causative agent of Rift Valley fever (RVF), a mosquito-borne viral zoonotic disease that poses a significant threat to domestic ruminants and human health in Africa. The RVFV is an encapsulated, negative-sense, single-stranded RNA virus with a tripartite segmented genome, containing L (large), M (medium) and S (small) segments. The S segment codes for two proteins, namely the nucleocapsid (N) protein and non-structural protein (NSs). There is evidence that the NSs protein is involved in virulence by blocking the expression of the interferon beta (IFN-β) promoter. It has been recently demonstrated that the SAP30-NSs-YY1 multiprotein complex represses the IFN-β promoter. Consequently, the interferon expression is blocked, allowing virus to replicate. A total of 45 isolates of RVFV recovered over a period of 53 years in 14 African countries, Madagascar and Saudi Arabia were characterized by full sequencing of the S segment of the virus. This data was added to another 27 strains of RVFV available on GenBank for phylogenetic analysis using MEGA4, giving a total of 72 strains analyzed. Alignments were made of the entire S segment, the NSs gene, the N gene, and their deduced amino acid sequences. The laboratory strains, clone 13, MP12 and Smithburn, were also included in the alignments. Two isolates were passaged ten times through two different amplification systems to asses the potential for sequence variation to occur in the original material through routine laboratory manipulations. Sequencing data was generated from the virus RNA present in the original clinical specimens and from the extracted RNA from the tenth passage of virus in each amplification system. The results showed 100% homology for each respective isolate, demonstrating that the RVFV S segment remained stable during ten serial passages in different propagation systems. Phylogenetic analysis was conducted on the naturally occurring RVFV strains (n = 72) and the findings indicate that circulating strains are compartmentalized and belong to one of three major lineages, namely Egyptian, western African, and central, eastern and southern African. The strains clustered in the Egyptian lineage had an average p-distance of 1.0%, the western African strains 0.9%, and the central, southern and eastern African strains 2.0%. The overall average p-distance was 2.5%, with a range from 0 to 4.1%. For the N gene, the range was from 0 to 4.2%, with an average of 2.2%. For the N protein, the range was from 0 to 2%, with an average of 0.2%. The NSs gene had a range of 0 to 4.6%, with an average of 2.4%. The NSs protein had a range of 0 to 3.8%, with an average of 1.7%. The intergenic region (IGR) had a range of 0 to 9.2%, with an average of 4.8%. Results of the study suggest that RVF outbreaks can result from either the rapid spread of a single strain over vast distances or from an increased activity of a strain circulating at an endemic level within an area/region during prolonged dry periods. Sequencing alignment showed that the length of the S segment ranged from 1690 to 1692 nucleotides. This difference in length was due to insertions and deletions found in the IGR, which is also the region with the most sequence divergence (4.8%). Both the NSs and N genes had neither insertions nor deletions, and were both found to be stable, though the NSs gene was slightly more variable than the N gene (2.5% versus 2.2%) The deduced amino acid sequences of the NSs protein were considerably more variable than that of the N protein (1.7% versus 0.2%). Alignment of the NSs protein demonstrated that the 5 cysteine residues at positions 39, 40, 150, 179 and 195, are highly conserved among the isolates analyzed. These residues are important for conservation of the three-dimensional structure of the protein and the formation of filamentous structures observed in cells infected with natural strains of RVFV. The NSs protein is now implicated as the major factor of virulence and that its pathogenicity is associated with the blocking of interferon production. Therefore, any amino acid changes that result in changes to the filamentous structure of the NSs protein might impact on the binding kinetics between the NSs protein, SAP30 (Sin3A Associated Protein 30) and YY1 (Yin Yang-1). There were 6 amino acid changes in the NSs-SAP30 binding domain, with one being unique to the live-attenuated Smithburn vaccine strain. Generated sequencing data contributes to global phylogenetic characterization of RVFV isolates and and molecular epidemiology of the virus. In addition, findings of this study will further aid investigation on reassortment events occurring between strains of RVFV and genetically related viruses, the role of the NSs protein in the replicative cycle of the virus, the pathogenic effects of the NSs protein within the RVFV-infected host cells, and might help to identify molecular basis of RVFV virulence.
22

Modélisation numérique 3D des caractéristiques physiques des segments de dorsale lente

Gac, Sébastien Goslin, Jean. January 2002 (has links) (PDF)
Thèse doctorat : Géosciences Marines : Brest : 2002. / Bibliogr. p. 233-242.
23

Modélisation numérique 3D des caractéristiques physiques des segments de dorsale lente

Gac, Sébastien Goslin, Jean. January 2006 (has links) (PDF)
Reproduction de : Thèse de doctorat : Géosciences Marines : Brest : 2002.
24

Spatial and temporal controls on the development of heterolithic, Lower Jurassic tidal deposits (Upper Are and Tilje Formations), Haltenbanken area, Offshore Norway.

Ichaso Demianiuk, Aitor Alexander 10 May 2012 (has links)
The stratigraphic organization of clastic successions deposited during the early synrift phase is controlled by the rates of tectonic subsidence and the growth of the master faults, which, coupled with eustatic sea-level changes, control the generation of accommodation. The highly heterolithic, Lower Jurassic Upper Åre and Tilje succession (100 to 300 m thick), which occurs in the Halten Terrace of offshore Norway, represents an excellent example of ancient synrift deposits that accumulated within a NNE-SSW-oriented structurally controlled embayment where sedimentation was dominated by tidal currents, with secondary influence by river and wave processes. Overall, the Tilje was deposited in a deltaic setting near the lowstand shoreline, forming a shallowing-upward succession, which is organized in two, thick, tabular second-order sequences. These sequences are separated by two main sequence boundaries (SB2 and SB3) associated with two main rift-related tectonic pulses. The first pulse formed SB2 and is believed to have exerted a major regional control on the geomorphology of the basin, causing a change from an open, wave-dominated setting (upper Åre Fm.) to a funnel-shaped, tide-dominated setting in the Tilje Fm. SB2 shows shallow incision into the underlying Åre Fm., and the overlying sediment accumulated predominantly in a distributary-mouth-bar environment. Sequence 3 rests erosively on Sequence 2, and is characterized by proximal tidal-fluvial distributary-channel fills and mouth-bar deposits showing at least 2 main oblique to axial fluvial input points, one from the N-NW and a second one from the NE, with overall increase in wave influence and deepening toward the S. Local rapid subsidence of elongated narrow hangingwalls associated with the active master faults exerted a subtle control on the succession thickness, as well as a local control on the location of the tidal-fluvial distributary channels by “tectonic axial funnelling” during the onset of the second-order base-level rises. The internal architecture and facies distribution are less complex than other thick tide-dominated successions worldwide, because the rate of creation of accommodation was sufficient to avoid channel amalgamation throughout most of the succession. / Thesis (Ph.D, Geological Sciences & Geological Engineering) -- Queen's University, 2012-05-09 23:39:27.538
25

Rapid development of optimized recombinant adenoviral vaccines for biosafety level 4 viruses

Sahib, Mickey M. 10 September 2010 (has links)
This thesis describes the production of adenovirus-based vaccines containing codon-optimized genes from Nipah virus and Crimean-Congo Hemorrhagic Fever virus. Genes encoding envelope proteins from Crimean-Congo Hemorrhagic Fever Virus and Nipah Virus were codon-optimized for translation in human cells and constructed using a modified method of non-gapped gene synthesis, while the entire M segment encoding the glycoprotein precursor for Crimean-Congo Hemorrhagic Fever Virus was commercially synthesized. Genes were cloned into recombinant human adenovirus serotype 5 and the resulting viral particles were amplified, titred and analyzed for in vivo efficacy. Results show that a modified method of non-gapped gene synthesis is an effective and efficient method of producing antigen-encoded DNA and at a fraction of the cost and time required for commercial synthesis. Furthermore, adenovirus-based vaccines induce both cellular and humoral immune responses providing for a highly efficacious vaccine during potential disease outbreaks, where time to completion is of utmost importance. This study has shown that recombinant adenoviral vaccines for Crimean-Congo Hemorrhagic Fever virus and Nipah virus can be produced rapidly and efficiently from virtual DNA sequence to optimized recombinant vaccines in just eight months.
26

REALISTISKT SPELKARAKTÄRSBETEENDE VID ANVÄNDANDET AV HMD

Åström, Axel January 2014 (has links)
Denna undersökning faller under två olika teoretiska fält, Sommerseth (2007), som använder sig av fenomenologins teorier för att förklara realism inom dataspel, och Freeman m.fl. (2000) som har en psykologisk utgångspunkt. Tillsammans används dessa teorier för att undersöka hur spelare uppfattar animationer i förhållande till Oculus Rift. Denna undersökning genomfördes genom åtta kvalitativa intervjuer, där deltagarna fick testa två olika versioner av ett spel, med olika animationer. Deltagarna filmades för att kunna observeras i efterhand. Data visar att spelare påverkas av tidigare erfarenheter och av spelkaraktärens fackla. Detta påverkade vilka animationer deltagarna uppfattade som realistiska. Data visade också på att Freemans m.fl. teori inte gick att applicera eftersom deltagarens spelvana tog över den kognitiva responsen. Vidare forskning kan göras på Freemans m.fl. metod för att se hur spelvanan hindrades, och även se hur spelare påverkas av ett annat objekt än en fackla.
27

Rapid development of optimized recombinant adenoviral vaccines for biosafety level 4 viruses

Sahib, Mickey M. 10 September 2010 (has links)
This thesis describes the production of adenovirus-based vaccines containing codon-optimized genes from Nipah virus and Crimean-Congo Hemorrhagic Fever virus. Genes encoding envelope proteins from Crimean-Congo Hemorrhagic Fever Virus and Nipah Virus were codon-optimized for translation in human cells and constructed using a modified method of non-gapped gene synthesis, while the entire M segment encoding the glycoprotein precursor for Crimean-Congo Hemorrhagic Fever Virus was commercially synthesized. Genes were cloned into recombinant human adenovirus serotype 5 and the resulting viral particles were amplified, titred and analyzed for in vivo efficacy. Results show that a modified method of non-gapped gene synthesis is an effective and efficient method of producing antigen-encoded DNA and at a fraction of the cost and time required for commercial synthesis. Furthermore, adenovirus-based vaccines induce both cellular and humoral immune responses providing for a highly efficacious vaccine during potential disease outbreaks, where time to completion is of utmost importance. This study has shown that recombinant adenoviral vaccines for Crimean-Congo Hemorrhagic Fever virus and Nipah virus can be produced rapidly and efficiently from virtual DNA sequence to optimized recombinant vaccines in just eight months.
28

Phylogeography and molecular phylogenetics of East African rodents assessing the role of vicariance /

Huhndorf, Michael H. Loew, Sabine Susanne. January 2007 (has links)
Thesis (Ph. D.)--Illinois State University, 2007. / Title from title page screen, viewed on July 16, 2008. Dissertation Committee: Sabine S. Loew (chair), Angelo P. Capparella, William L. Perry, John M. Bates, Julian C. Kerbis Peterhans. Includes bibliographical references (leaves 89-99) and abstract. Also available in print.
29

Karoo rifting im Morondava Becken, Madagaskar: fazielle Entwicklung, Kinematik und Dynamik eines polyphasen Riftbeckens

Bremer, Florian Heinrich. Unknown Date (has links) (PDF)
Techn. Universiẗat, Diss., 2005--Berlin.
30

Engendering the Metabolic Rift: A Feminist Political Ecology of Agrofuels

Dockstader, Sue, Dockstader, Sue January 2012 (has links)
This thesis analyzes the gendered impacts of plant-based alternatives to petroleum, commonly called biofuels. Synthesizing case studies, scientific research and policies papers, this theoretical work adopts the term “agrofuels” coined by the peasant organization La Vía Campesina to reflect the true nature of these commodities – one of dispossession and ecological destruction. This paper documents the falsity of the claim that the fuels are “sustainable” by presenting facts linking them to deforestation, loss and pollution of water sources, destruction of important biodiversity and the knowledge that maintains this diversity, as well as economic exploitation. Most importantly, I verify that the adoption of agrofuel expansion exacerbates gendered patterns of exclusion and, in most cases, worsens women’s positions within the communities targeted for feedstock production with regard to land tenure, household energy maintenance, independent income and physical integrity.

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