Thesis (Ph. D.)--Ohio State University, 2005. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2006 Sep 19

Made available in DSpace on 2014-06-11T19:22:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-05-26Bitstream added on 2014-06-13T20:28:40Z : No. of bitstreams: 1 francisco_cj_me_jabo.pdf: 404375 bytes, checksum: ad2555bf63840b01713a9639cefe7472 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / Avaliou-se no presente trabalho, a fauna parasitária de Oreochromis niloticus, Cyprinus carpio, Hoplias malabaricus, Ictalurus punctatus, Rhandia quelen mantidos em monocultivo ou policultivo. Os peixes foram capturados entre setembro a dezembro de 2004, totalizando 43 peixes, sendo 23 de policultivo e 20 de monocultivo. Houve diferença significativa (P<0,05) na intensidade média e prevalência de monogenoidea, sendo, 196,45(55%) policultivo e 37,16(26%) em monocultivo. Os tricodinídeos apresentaram 136,66(60%) em policultivo e 63,0(13%) em monocultivo. A Lamproglena sp (Lernaiedae) com intensidade e prevalência de 3,14(35%) em policultivo, assim como Lernaea cyprinacea (copepoditos) intensidade e prevalência de 12,85(35%), respectivamente, também em policultivo. Nos mantidos em monocultivo houve relevante presença de Piscinoodinium pillulare, com diferença significativa (p<0,05), intensidade (63,7) e prevalência (43,5%).Um espécime de Lernaea cyprinacea adulta foi encontrado em policultivo e um Argulus sp em monocultivo. Registra-se pela primeira vez a análise comparativa da helmintofauna de peixes mantidos em monocultivo e policultivo da região do médio Vale do Itajaí, SC. / The parasitic fauna of the Oreochromis niloticus, Cyprinus carpio, Hoplias malabaricus, Ictalurus punctatus, Rhandia quelen kept in mono and polyculture ponds was evaluated.A total of 43 fishes were captured between september and dezember 2004, 23 from monoculture and 20 from a polyculture system.There was significant difference (P<0,05) in the average intensity and prevalence of the different parasites. For the fishes in the poly and monoculture system the respective values are: monogenoidea, 196,45(55%) and 37,16(26%); Tricodiníds, 136,66(60%) and 63,0(13%); Lamproglena sp. (Lernaiedae). Only in polyculture systems, Lamproglena sp. (Lernaiedae), 3,14(35%) and Lernae cyprinacea (copepoditos), 12,85 (35%) were found.The fishes kept in monoculture systems there was relevant presence of Piscinoodinium pillulare with significant difference (p<0,05), average intensity (63,0) and prevalence (43,5%).An adult specimen of Lernaea cyprinacea was found in the fish from the polyculture pond and one of Argulus sp in the monoculture one. It is reported for the first time the comparative analysis of parasitic fauna in fishes maintained in mono and polyculture ponds in the middle Itajai valley (Santa Catarina, Brazil).

Increases in temperature and precipitation predicted under global warming are expected to be most pronounced and thus have their greatest impact on ecosystems at high latitudes. Insects constitute a major component of the foodwebs of terrestrial ecosystems and should be among the first organisms to show noticeable responses to predicted global warming, especially in the Arctic where climatic conditions are often limiting. However, interactions among species must also be taken into account. The genus Gynaephora Hübner (Lepidoptera: Lymantriidae) is represented in North America by two species, G. groenlandica (Wocke) and G. rossii (Curtis), and their geographic distributions overlap broadly across the Canadian Arctic. Previous studies have examined the biology, ecology, and physiology of these two species and have revealed many adaptations to the Arctic environment, but the immature stages of these insects have been misidentified even in recently published reports. Both species are found at Alexandra Fiord, Ellesmere Island, a High Arctic oasis largely isolated by expanses of ocean and icecap, and the population of G. groenlandica at this site is thought to be limited mainly by parasitoid-induced mortality rather than by climatic conditions. Field observations, surveys, and temperature-manipulation experiments were conducted at Alexandra Fiord during the spring and summer of 1994, 1995, and 1996; laboratory rearing was conducted under controlled conditions at the University of Victoria in the spring of 1996 and 1997. Immature stages of both species of Gynaephora were described and illustrated, and all species of insect parasitoids using Gynaephora species as hosts at Alexandra Fiord were identified. Life histories and seasonal phenologies for Gynaephora species and their insect parasitoids were elucidated from field studies, and temperature/development relationships for selected stages of most of these species were derived from laboratory rearing. The results of field studies and laboratory rearing were compared and used to formulate predictions about the responses of these insects to predicted global warming. Immature stages of the two species of Gynaephora are easily distinguished by differences in the colour patterns, form, and overall length of the larval hairs and by the structure of their cocoons. Both species of Gynaephora complete metamorphosis and reproduction within a single growing season but spread larval development over a number of years. In G. groenlandica, seven larval instars and annual moulting combine to produce a seven year life cycle whereas G. rossii develops through six larval instars at a rate of two or three moults per year, resulting in a three or four year life cycle. The parasitoid complex at Alexandra Fiord consists of three primary parasitoids, Hyposoter pectinatus (Thomson) (Hymenoptera: Ichneumonidae), Exorista n.sp. (Diptera: Tachinidae), and Chetogena gelida (Coquillett) (Diptera: Tachinidae), and one hyperparasitoid, Cryptus leechi Mason (Hymenoptera: Ichneumonidae). All of the parasitoids are univoltine, although H. pectinatus may undergo delayed development in some cases, and each of the primary parasitoids relies primarily on a single larval instar for hosts whereas the hyperparasitoid attacks the primary parasitoids during their metamorphosis. Seasonal phenologies of the parasitoids provide optimal access to new hosts but parasitoid-avoidance strategies of Gynaephora larvae ensure that a proportion of their populations escape parasitism. Laboratory rearing showed that the relative timing of host and parasitoid seasonal phenologies is maintained over a broad range of temperatures; therefore, temperature increases predicted under global warming are unlikely to have any great effect on host-parasitoid interactions. However, increased cloudiness associated with the predicted increase in precipitation might have profound effects resulting from lower ground-level temperatures caused by a lack of solar heating. The extent of this effect is uncertain but might lead to reproductive failure in Gynaephora species, with similar repercussions for the insect parasitoids. / Graduate

Malaria remains the most serious and deadly parasitic disease, affecting millions of people mostly in the poorest countries in the world. With no vaccine likely in the foreseeable future, drugs remain the best means of controlling the disease. Plants have provided most of the antimalarial drugs so far and it is likely that more antimalarial drugs will be discovered in this way. A previous study on South African plants yielded very good results on the extract level. In this study Croton steenkampianus leaf extract was selected for isolation of active principles. Bio-guided fractionation of the extract was done on silica column chromatography and Sephadex column chromatography. Five compounds, two favonoids, a triterpene and two new diterpenes, with a novel skeleton were isolated. Compounds were identified with NMR, MS and X-ray crystallography. Antiplasmodial activity of the compounds varied from moderate to excellent, with crotrene A having excellent activity. Further studies on the antimalarial potential of this compound are planned. Cytotoxicity of compounds and extract were determined against human lymphocytes. Results obtained had an ID50 between >16,61 µg/ml. The therapeutic indexes were between 2.75 and 55.18, showing poor to moderate selectivity towards Plasmodium. Crotrene A had the best therapeutic index and more detailed studies on its cytotoxicity are necessary. Resistance to antimalarial drugs is a major problem in effective treatment of the disease. One way of overcoming this problem is combination drugs working synergistically. Chloroquine the most affordable antimalarial drug was combined with the isolated compounds. Two compounds showed synergistic activity with crotrene A having excellent activity, completely reversing chloroquine resistance. This combination of drugs showed no synergistic cytotoxic effects and its potential as a drug will be further investigated. The mode of action of antimalarial drugs can provide useful information about the long term potential and the likelihood of resistance development. Crotrene A was subjected to a basic test to determine a possible mode of action. Results showed a marked effect in the early phase of development (rings). The results suggest a very potent mode of action able to reduce the amount of parasites quickly and this holds promise for further development of this compound. / Thesis (DPhil)--University of Pretoria, 2008. / Plant Science / unrestricted

The number of tissue eosinophils were counted and phospholiphase B activity was assayed in the intestines of nonsensitized and sensitized and sensitized mice infected with Trichinella spiralis.

<p> In this dissertation I examine a distinction made in Speech Act Theory between normal uses of language and uses of language that are said to be parasitic on them. Fictional, theatrical, comedic and metaphoric uses of language may be said to be parasitic on normal language in so far as their intelligibility requires a prior grasp of the rules or conventions of normal language such as is used in everyday cases of asserting, promising, marrying and ordering, for instance.</p> <p> Jacques Derrida argued that uses of language could not be determined as exclusively either normal or parasitic and that thus such a distinction could not be made. That is, he argued that it was not possible to make a distinction between fictional promises and real life promises, for instance; or between literal uses of words and metaphorical uses. I show that the distinction can be made and that, although uses of language cannot be determined as exclusively either normal or parasitic in the work of J. L. Austin, they can be in that of John R. Searle. </p> <p> In arguing for this thesis, I show how Searle, in his attempt to defend Austin and Speech Act Theory against Derrida's criticisms, failed to appreciate many aspects of Derrida's work and thus misconstrued his critique and defended Austin and Speech Act Theory against somewhat of a straw man. </p> / Thesis / Doctor of Philosophy (PhD)

No description available.

Switching and average models are developed for major three-phase PWM converters. The models are correct for the case when the voltage sources or capacitors with nonzero parasitic resistances are placed across the converter dc port or ac terminals. The effects of the parasitic resistances are described by additional time-varying terms in the average models depending not only on the duty cycle values, but also on the modulation strategy. For analysis purposes, the terms due to parasitic resistances can be approximated by their fundamental frequency components ( dc or line/output frequency). A new small-signal model in the rotating coordinates is developed for a uniformly sampled three-phase modulator. The model reveals that the uniform sampling introduces delays in the control inputs and cross-coupling between the control inputs. Furthermore, the model is time varying causing the complete small-signal model consisting of the modulator and converter small signal models in the rotating coordinates to become time-varying. Based on the derived expressions, the worst-case point for the control design can be identified. A modulation strategy which reduces delay due to the uniform sampling can be selected. The modulator model is partially verified experimentally. Influence of delays due to the uniformly sampled PWM and digital implementation is investigated in the closed-loop control design for the boost rectifier. Designs of standard control schemes, consisting of inner current loops and a superimposed voltage loop, are presented and verified experimentally. They can be extended to other three-phase PWM converters. A new control algorithm is developed and verified experimentally for power factor correction (PFC) applications of three-phase PWM rectifiers, where a rectifier is preceded by an input filter. The algorithm provides output voltage regulation and input displacement factor (IDF) compensation without resorting to the control of input filter states. It allows separate design of the input filter and the rectifier closed-loop control. A criterion for small-signal stability of the integrated system, consisting of the rectifier with output voltage regulation and the input filter, has been formulated and applied to the buck rectifier with the input filter. / Ph. D.

Water quality monitoring in Canada is essential to providing safe water to all. Indigenous and remote communities, many of which are under boiling drinking water advisories, lack availability and/or funding to water monitoring resources. A low-cost, point-of-care detection mechanism has been proposed for the detection of aqueous ammonia and protozoan parasites, which affect the safety of a source of water. An ammonia fluorescence responsive hydrogel, based on the fluorescence quenching of rare earth metal Europium (Eu3+) upon contact with aqueous ammonia, has been proposed to be incorporated into a microfluidic device, which utilizes shadow imaging and flow analysis to detect parasitic (oo)cysts of Cryptosporidium and Giardia, two of the most prevalent protozoan parasites which cause gastrointestinal illness around the world. Fabrication of the ammonia sensitive hydrogel was completed, and the essential components to the ammonia sensitivity were determined. Chemical analysis and solvent modifications found that Formamide is the essential solvent to maintain ammonia sensitivity. A literature review into the current detection mechanisms of Cryptosporidium and Giardia was completed to provide a reference and starting point for the development of the low-cost, point-of-care device proposed in this thesis. Baseline images of Cryptosporidium parvum and Giardia lamblia were captured to provide a reference for the development of a particle tracking algorithm to be used in the microfluidic device. The images captured highlight morphological features essential to developing a tracking mechanism based on the morphology of the (oo)cysts. / Thesis / Master of Science in Biomedical Engineering / Water quality monitoring for remote and Indigenous communities is needed to provide safe water to all. Detection of aqueous ammonia by fluorescent hydrogel, and parasitic cysts by flow analysis, provides a low-cost, point-of-care detection mechanism. A fluorescence responsive hydrogel for aqueous ammonia detection was produced and the essential components for ammonia responsiveness were determined. Detection mechanisms of parasites Cryptosporidium and Giardia, two of the most prevalent parasitic protozoans causing human gastrointestinal illness, were analyzed and compared. Baseline images of the parasitic (oo)cysts were captured by conventional microscopy for the training of particle tracking algorithms to be implemented into a microfluidic device. The microfluidic device detection mechanism will utilize shadow imaging and flow analysis to detect parasitic (oo)cysts.

M.Ing. / This study considers improving the azimuth beam steering resolution of the circular Switched Parasitic Array (SPA) antennas (made up of dipoles) by a factor of two or more. In circular SPA antennas, beam steering is conventionally achieved by open-circuiting and shortcircuiting different parasitic elements and usually only one parasitic element is open-circuited at a time. However, such an approach results in low beam steering resolutions especially for the SPA antennas with few parasitic elements. In order to increase the azimuth beam steering resolution for the circular SPA antennas, two beam steering methods are proposed in this research work. In the first method, parasitic elements are open-circuited and short-circuited based on different combinations of the parasitic elements and the possible switch states. The proposed method was first validated by simulation tests using the MATLAB tool and WIPL-D. A prototype of the circular SPA antenna consisting of five elements was then implemented. It is noted that the simulation and measurement results match very well at 2.4 GHz. In order to have at least two combinations (from the first method) with almost similar gain and return loss, another simpler beam steering method was developed. The latter method is based on simultaneously open-circuiting either two or three neighbouring parasitic elements. The performance of the second method was studied through simulations using the circular SPA antenna geometries consisting of five, seven and nine elements. These geometries were first optimized (for gain and input impedance) and then modelled using WIPL-D. It was observed that the two methods double the azimuth beam steering resolution of the circular SPA antennas when compared to the conventional beam steering approaches of open-circuiting one parasitic element at a time. Variations in the structural parameters of the five elements circular SPA antenna at 2.4GHz were also investigated. In this procedure, the effects of variations (also considered as random errors) in the structural parameters (or antenna dimensions) on the performance of the SPA antennas were examined. Firstly, variations in each structural parameter were modelled with other structural parameters fixed as per specifications. Thereafter, effects of combined errors were also investigated. The simulation results demonstrated that variations in the structural parameter can either increase or decrease the gain and input impedance of the SPA antenna depending on the given specifications. The gain and input impedance sensitivities per variations in each structural parameter were computed to determine the degree at which the gain and input impedance can vary for a predefined change (error) in the structural parameter.