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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.
251

Hidden Creatures – systematics of the Euphorinae (Hymenoptera)

Stigenberg, Julia January 2013 (has links)
Parasitic wasps constitute one of the last remaining frontiers in the charting of animal diversity. The Braconidae is the second most species-rich family of parasitic wasps; the world fauna has been estimated at 40 000 species and the Swedish fauna is believed to include a little more than 2 000 species, 1 200 of which are currently documented. This thesis is a contribution to the rapidly increasing knowledge of braconid diversity. In paper I, a new gregarious parasitoid, Meteorus acerbiavorus sp. nov. (Braconidae: Eupohrinae), is described from specimens reared from the cocoons of the butterfly Acerbia alpina (Quensel) (Lepidoptera, Arctiidae) in northwestern Finnish Lapland. Based on a molecular phylogenetic analysis, the new species is shown to belong to the M. rubens species group. In the second paper, the Western Palearctic fauna of the tribe is revised, seven new species are described and a key to the Western Palearctic species is presented. Two molecular markers, 28S and COI, are used to study phylogenetic relationships in the tribe. The molecular results showed that the Meteorini fall into four well supported clades. The results also reveal a considerable cryptic species diversity. The third paper deals with distributional, phenological and in many cases rearing data from nearly 2 500 specimens (44 species) of the Meteorini in the collection of the National Museums of Scotland (NMS), Edinburgh. Patterns in the breadth of host ranges are discussed in relation to a reiterated speciation hypothesis. Paper IV examines the phylogenetic relationships of the entire subfamily Euphorinae based upon four gene regions (18S, CAD, 28S D2, and COI). A revised classification of the Euphorinae is proposed that recognizes 55 genera and 14 tribes. Our study shows that early members of the Euphorinae were parasitoids of coleopteran larvae, with a host shift to larval Lepidoptera, adult or immature hosts in the Hemiptera, Hymenoptera, Neuroptera, Orthoptera and Psocoptera. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: In press. Paper 4: Manuscript.</p>
252

Pathogens and other threats to Pinus contorta in northern Sweden

Karlman, Margareta January 1984 (has links)
The background to the large-scale planting of Pinus contorta in northern Sweden is reviewed with an account of the distribution and characteristics ofPi nus contorta within its natural range in western North America. The threatsto successful planting of exotics are discussed in relation to the historicalbackground. Attention is also drawn to parasitic fungi which are infectingPi nus contorta in western Canada, and to the potential threat they representto the indigenous Pi nus sylvestris in Sweden.During a seven-year-period 100 provenances of Pi nus contorta have been investigatedannually with respect to different kinds of damage, primarilythose by parasitic fungi. The study indicates that damage to Pi nus contortaprimarily occurs during the first ten years after planting. Northern provenancesof Pi nus contorta are generally more resistant to pathogens than southernprovenances. Weather damage occurs almost every year among trees ofsouthern and coastal provenance. Even trees of northern provenance have sufferedfrom weather damage due to temperature oscillations during shoot elongation.Severe weather damage is a predisposing factor to infection by secondarypathogens primarily.Gremmeniella abietina. There is a minor correlation betweensevere weather damage and Phacidium infestans. Even northern provenancesof Pinus contorta are infected by Phacidi um infestans in high altitude standsin northern Sweden. Snow b light infection is, however, of a minor importanceto lodgepole pine than to Scots pine due to the rapid early growth of the former.The most productive plants of both Pinus contorta and Pinus sylvestrisare attacked by Phacidi um infestans. Plants not infected by snow b light havea lower height growth than those infected.Severe infection by Gremmeniella abietina has been recorded after voleattack, even among northern provenances of lodgepole pine. So far Pinus contortahas mainly been infected by the same fungi as Pinus sylvestris, with the |exception of Melampsora pinitorqua and Lophodermella sul ci gena. Pinus contorta iis, however more susceptible to infection by Gremmeniella abietina in connec- !tion with vole damage, depending on the more severe injuries to lodgepole pinethan to Scots pine.So far vole damage has been the most severe threat to Pinus contorta innorthern Sweden. Voles prefer lodgepole pine to Scots pine providing vole populationis moderate. At times of high vole populations even Scots pine suffersdamage. Voles attack Pinus contorta even 14 years after planting. The differencein frequency of vole damage among provenances strongly decreased with increasedvole population and repeated attacks from year to year.Tree tilting was first noted five to eight years after planting on sites exposedto strong winds and severe icing.In the central parts of northern Sweden most provenances of Pinus contortaare less attacked by pathogens than the indigenous Pinus sylvestris, and inorthern provenances of lodgepole pine are remarkably productive in thenorthernmost site, despite a relatively high frequency of Phacidium infestar^.Later investigations indicate, however, more severe damage to Pinuscontorta with increasing latitude and altitude in northern Sweden. / digitalisering@umu
253

Full-wave Surface Integral Equation Method for Electromagnetic-circuit Simulation of Three-dimensional Interconnects in Layered Media

Karsilayan, Nur 2010 May 1900 (has links)
A new full-wave surface impedance integral equation method is presented for three-dimensional arbitrary-shaped interconnect parasitic extraction in layered media. Various new ways of applying voltage and current excitations for electromagnetic-circuit simulation are introduced. A new algorithm is proposed for matrix formation of electromagnetic-circuit simulation, low frequency solution and layered media so that it can be easily integrated to a Rao-Wilton-Glisson based method of moment code. Two mixed potential integral equation forms of the electric field integral equation are adapted along with the Michalski-Mosig formulations for layered kernels to model electromagnetic interactions of interconnects in layered media over a conducting substrate. The layered kernels are computed directly for controllable accuracy. The proposed methods are validated against existing methods for both electromagnetic and electromagnetic-circuit problems.
254

P15 trypanosome microtubule associated protein : structure/function analysis and vaccine development for the prevention of African sleeping sickness.

Rasooly, Reuven. January 2001 (has links)
Trypanosomes are hemoflagellated protozoan parasites causing chagas disease in South America, Leishmaniasis throughout the world, and African sleeping sickness in humans and nagana in animals in Africa. About 55 million people and 25 million cattle have been estimated to be at risk of contracting African sleeping sickness or nagana respectively. Once injected into the blood stream via the bite of a tsetse fly, the parasite evades the host's immune response by repeatedly changing its surface antigens, thus making the development of a vaccine seem impossible. Furthermore, chemotherapy existing today can be toxic, suggesting that novel methods to prevent diseases caused by trypanosomes are essential. All parasites of the Trypanosomatidae family contain unique microtubular structures called the subpellicular microtubules. Microtubules are made of tubulin and of microtubule associated proteins (MAPs). Unlike other microtubules, the subpellicular microtubules are crosslinked to one another and to the plasma membrane. The unique structure of the subpellicular microtubules has been attributed to unique trypanosome subpellicular MAPs which stabilize the microtubule polymers and crosslink them to one another. Three unique types of subpellicular MAPs have been identified: MARP, which is a high molecular mass MAP that stabilizes microtubules, p52 that is a 52kDa MAP which crosslinks microtubules, and pI5, which is a I5kDa protein which bundles microtubules. Because trypanosome MAPs have been shown to be unique to these parasites, these molecules could serve as useful target sites for therapy. In this study pI5 was cloned and sequenced and shown to contain highly organized, nearly identical tandem repeats with a periodicity of 10 amino acids, rich in positively charged and in hydrophobic amino acids. It was shown that pI5 can also bind phospholipids, suggesting that it may not only bundle the microtubule polymer through its positively charged amino acids but may also crosslink the microtubules to the plasma membrane through its hydrophobic regions, thus contributing to the stable structure of the subpellicular microtubules. To test for the efficiency of pI5 as a vaccine candidate, the recombinant pI5 was cloned into an adenovirus, which was used as a vaccine delivery system for pI5. Mice were vaccinated with the native purified pI5, with the expressed recombinant pI5 and with the adenovirus containing the recombinant pI5 gene (Ad-pI5). The results indicated that pI5 protected 100% of the animals vaccinated with the recombinant molecule (8/8), and 87% of the animals vaccinated with the native protein (7/S), while none of the control animals were protected. Animals that were vaccinated with the Ad-pI5 were protected but so were the control animals vaccinated with an adenovirus containing the lacZ gene. We have shown that vaccination with the adenovirus is associated with an elevated CDS+ T cell response which is known to be trypanostatic (S6), suggesting that animals vaccinated with Ad-pIS may have been protected not only by the specific anti-plS response but also by non specific immunity that was induced by the adenovirus itself. The source of the native and recombinant pI5 was from a different strain of T. brucei that was used for challenge. Since the subpellicular microtubules are common to all members of the Trypanosomatidae family, pI5 may ultimately serve as a common target for therapy to all types of diseases caused by trypanosomes. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2001.
255

Adapting the Standard SIR Disease Model in Order to Track and Predict the Spreading of the EBOLA Virus Using Twitter Data

Smailhodzic, Armin 01 May 2015 (has links)
A method has been developed to track infectious diseases by using data mining of active Twitter accounts and its efficacy was demonstrated during the West African Ebola outbreak of 2014. Using a meme based n-gram semantic usage model to search the Twitter database for indications of illness, flight and death from the spread of Ebola in Africa, principally from Guinea, Sierra Leone and Liberia. Memes of interest relate disease to location and severity and are coupled to the density of Tweets and re-Tweets. The meme spreads through the community of social users in a fashion similar to nonlinear wave propagation- like a shock wave, visualized as a spike in Tweet activity. The spreading was modeled as a system isomorphic to a modified SIR (Susceptible, Infected, Removed disease model) system of three coupled nonlinear differential equations using Twitter variables. The nonlinear terms in this model lead to feedback mechanisms that result in unusual behavior that does not always reduce the spread of the disease. The resulting geographic Tweet densities are coupled to geographic maps of the region. These maps have specific threat levels that are ported to a mobile application (app) and can be used by travelers to assess the relative safety of the region they will be in.
256

Relationships between environmental risk factors, parasitic infections and health outcomes in an urban African setting

Tshikuka Mulumba, Jose-Gaby January 1995 (has links)
The relationships between parasitic infections, environmental and living conditions, and health outcomes were studied in subdivisions of lower (LSES) and higher (HSES) socio-economic status Lubumbashi, Zaire. The two LSES subdivisions had higher prevalences of Plasmodium infection and higher rates of stunting, abdominal pain and low packed cell volume (PCV) than the HSES subdivision. The prevalence and intensity of Ascaris lumbricoides and Trichuris trichiura was not associated with socio-economic status. Maternal education was a significant predictor of A. lumbricoides intensity in both LSES and HSES subdivisions. Factors related to poor sanitation were risk factors for A. lumbricoides in LSES subdivisions, whereas a high ratio of relatives to immediate family members per household predicted high intensity infection in the HSES subdivision. The risk of stunting was higher in children with A. lumbricoides, that of wasting was higher in children with A. lumbricoides or T. trichiura whereas the risk of kwashiorkor was high with T. trichiura but very reduced in those with A. lumbricoides. The four most common clinical conditions were diarrhea, abdominal pain, fever and low PCV. Hookworm infection, T. trichiura infection, young age and residence in LSES subdivisions were determinants of diarrhea. T. trichiura infection, young age and living in a LSES subdivision were risk factors for abdominal pain. Plasmodium infection and young age were associated with fever. LSES was predictive of low PCV. No combination of parasites had antagonistic or synergistic effects on clinical indicators examined. Based on this study, it is suggested that one parasite will increase the risk of infection with another. Although maternal education should be improved in all subdivisions, attention to sanitation, crowding and diet in the LSES subdivisions, and to the role of relatives and visitors in parasite transmission in the HSES subdivision should be priorities.
257

Estimation and optimization of layout parasitics for silicon-based millimeter-wave integrated circuits

Sen, Padmanava 06 November 2007 (has links)
Millimeter-wave has been a medium for automotive, sensor, and defense applications for a long time. But, a fully integrated silicon-based transceiver at 60 GHz or higher frequencies has become the driving force for recent research activities in integrated millimeter-wave (MMW) circuit designs. However, no integrated compact high-performance millimeter-wave system can be designed without accurate estimation and optimization of layout parasitics. In this dissertation, the estimation, modeling and optimization of parasitic effects as well as the verification of extraction methodologies for RF/MMW applications are investigated. Different circuit design- and layout-examples are considered with stress on the inclusion and optimization of wire/interconnect parasitics. A novel methodology is proposed to reduce the number of design-passes and to include layout parasitics in the design optimization procedure. An automated verification procedure for existing parasitic extraction tools is developed. Neural-network-based models are used to demonstrate the effectiveness of artificial intelligence techniques for characterizing parasitic components. The parasitic sensitivities for selected millimeter-wave circuits are demonstrated, and a parasitic benchmarking procedure is developed using MMW oscillators. Measurement results of several circuits that are implemented in state-of-the-art CMOS and SiGe-BiCMOS processes are used to demonstrate the role of parasitics and the systematic design methodology including parasitics.
258

Burdur il merkezi ilköğretim okullarındaki çocuklarda bağırsak parazitlerinin görülme sıklığı/

Kılınç, Ahmet Selçuk. Kişioğlu, Ahmet Nesimi. January 2006 (has links) (PDF)
Tez (Yüksek Lisans) - Süleyman Demirel Üniversitesi, Sağlık Bilimleri Enstitüsü, Halk Sağlığı Anabilim Dalı, 2006. / Bibliyografya var.
259

Diagnosis of infection with toxoplasma gondii in pregnant women, neonates and immunocompromised patients /

Petersen, Eskild, January 2005 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 8 uppsatser.
260

The effect of malaria and intestinal helminth coinfection on birth outcomes in Ghana

Yatich, Nelly J. January 2008 (has links) (PDF)
Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Title from first page of PDF file (viewed Feb. 19, 2009). Includes bibliographical references.

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