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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

Influência da intensidade de chuva em diferentes épocas e da palha de cana-de-açúcar sobre a eficácia de herbicidas aplicados em pré-emergência no controle da tiririca (Cyperus rotundus L.) / Identification of proteins from the cambial region of Eucalyptus grandis by bidimensional electrophoresis and mass spectrometry

Fernanda de Simoni 22 May 2006 (has links)
O presente trabalho foi desenvolvido com o objetivo de avaliar os efeitos da intensidade de chuva e diferentes quantidades de palha de cana-de-açúcar sobre a eficácia de herbicidas aplicados em pré-emergência no controle da tiririca. Foram realizados dois experimentos, ambos conduzidos em casa-de-vegetação. O delineamento experimental adotado foi o de blocos casualizados, com 4 repetições, para os dois experimentos. No primeiro experimento os tratamentos foram distribuídos em um esquema fatorial 3 x 3 x 2 x 2, constituídos pela combinação entre quantidades de cobertura morta de palha de cana-de-açúcar que foram adicionadas à superfície do solo (0, 10, 20 t/ha), herbicidas aplicados em pré-emergência (sulfentrazone a 0,8 kg i.a./ha e imazapic a 147 g i.a./ha) e um tratamento sem aplicação de herbicida, intensidades de chuva (10 e 20 mm), e épocas em que foram simuladas chuvas após a aplicação dos herbicidas (24 e 168 horas). No segundo experimento os tratamentos foram distribuídos em um esquema fatorial 2 x 3 x 5, constituídos pela combinação entre quantidades de cobertura morta de palha de cana-de-açúcar (0, 15 t/ha), herbicidas aplicados em pré-emergência (sulfentrazone a 0,8 kg i.a./ha e imazapic a 147 g i.a./ha) e um tratamento sem aplicação de herbicida, e épocas em que foi simulada chuva após a aplicação dos herbicidas (0, 3, 6, 9 e 12 dias). Em ambos experimentos foram avaliados: o número de plantas por vaso, biomassas secas da parte aérea e das estruturas do sistema subterrâneo, e número de tubérculos e bulbos sadios. A partir da análise dos resultados, para o primeiro experimento conclui-se que, para o herbicida sulfentrazone, a presença de 20 t/ha de palha de cana-de-açúcar diminuiu a eficácia do herbicida. O herbicida imazapic teve um bom desempenho tanto na ausência quanto na presença de palha, e causou redução das variáveis estudadas independente da intensidade de chuva. A intensidade de chuva de 10 mm, não foi suficiente para transpor o herbicida sulfentrazone na quantidade de 20 t/ha de palha. Já a intensidade de 20 mm foi suficiente para lixiviar o herbicida até mesmo na maior quantidade de palha. O herbicida sulfentrazone suporta mais a permanência na palha, pois apresentou melhor eficácia em relação ao imazapic, quando a chuva foi simulada 168 horas após a aplicação dos herbicidas. Para o segundo experimento pode-se concluir que, as épocas em que foram simuladas as chuvas, não afetaram as variáveis estudadas, não havendo, portanto, diferença se a chuva ocorreu no dia em que foi aplicado o herbicida, ou se ocorreu um período sem chuva de 12 dias. Os herbicidas sulfentrazone e imazapic reduziram o número de plantas, o número de tubérculos, biomassa seca de bulbos, biomassa seca de rizoma e raiz, e biomassa seca da parte aérea, independente da presença de palha. / The present work was developed with the objective of assessing the effects of the intensity of rain and different quantities of sugar cane mulch residue on the efficacy of herbicides applied in pre-emergence for the purple nutsedge control. Two experiments were performed, both conducted in greenhouses. The experiments were performed by randomly choosing blocks with four repetitions. In the first experiment, the treatments were distributed in a factorial scheme 3 x 3 x 2 x 2, constituted by the combination between quantities of dead coverage of sugar cane mulch residue which were added to the soil surface (0, 10, 20 t/ha), herbicides applied in preemergence (sulfentrazone at 0,8 kg i.a./ha and imazapic at 147 g i.a./ha) and a treatment without the application of herbicides, rain intensities (10 and 20 mm), and seasons in which were simulated rains after the application of herbicides (24 and 168 hours). In the second experiment, the treatments were distributed in a factorial scheme 2 x 3 x 5, constituted by the combination between quantities of dead covering of sugar cane mulch residue (0, 15, t/ha), herbicides applied in pre-emergence (sulfentrazone at 0,8 kg i.a./ha and imazapic at 147 g i.a./ha), a treatment without the application of herbicides and seasons in which were simulated rains after the application of herbicides (0, 3, 6, and 12 days). It was evaluated in both experiments: the number of plants per vase, dry biomasses from the aerial parts, from the underground system structures and the number of healthy tubers and bulbs. From the analysis of the results of the first experiment, it may conclude that, to the herbicide sulfentrazone, the presence of 20 t/ha of sugar cane mulch residue diminished its efficacy. The herbicide imazapic had a good performance with the absence as well as with the presence of the mulch residue, and caused a reduction in the varieties studied independently of the intensity of rain. The intensity of rain of 10 mm, wasn’t sufficient to overpass the herbicide sulfentrazone in the quantity of 20 t/ha of mulch residue. But the intensity of 20 mm was enough to lixiviate the herbicide even in the biggest quantity of mulch residue. The herbicide sulfentrazone endures more the abiding on the mulch residue, because it presented a better efficacy in relation to the imazapic, when the rain was simulated 168 hours after the application of the herbicides. From the second experiment it may conclude that the season in which was simulated rains, it didn't affect the varieties studied, therefore there was no difference when the rain occurred on the day when the herbicide was applied, or if it occurred on a 12 day period without rain. The herbicides sulfentrazone and imazapic reduced the number of plants, the number of tubers, dry biomass of bulbs, dry biomass of rhizoma roots and dry biomass of the aerial parts, independently of the presence of mulch residue.
22

Climate change and disease at the human-wildlife interface

Van de Vuurst, Victoria Paige 13 July 2021 (has links)
Recent research has shown that climate change had and will likely continue to have impacts on biological processes, including the propagation of infectious and zoonotic diseases. Assessments of local level impacts at the human-wildlife interface are imperative for stakeholders and policy makers, and empirical review of such research is undoubtedly necessary to understand the current state of the field, gaps of knowledge, and to identify future lines of research. In that vein, this thesis focuses on the impacts of climate change on disease at the human-wildlife interface. Specifically, my thesis works to quantify the recent temporal and spatial distribution of empirical research linking climate change with changes in the burden of infectious diseases (Chapter 2). This retrospective scoping of the last five years of empirical research identified if, and to what extent, there are biases in the diseases, species, or geographic areas studied within this scientific field. My study revealed both geographic and topical biases within the scope of recent literature, with an overwhelming emphasis on vector-borne diseases in temperate areas. There was also unequal representation in publication demographics of authors and institutions with most research originating from well developed countries. As a proof-of-concept case study, my thesis provides an empirical assessment of the plausible climatic drivers of a wildlife-disease transmission risk in an understudied region (Chapter 3), which could function to fill some of the identified research gaps in Chapter 2. Therein, my work assessed the impacts of climate variation from the last century on the environmental suitability of the rabies host Desmodus rotundus (common vampire bat) in Latin America. Findings revealed that average and standard deviation of temperature were the most important drivers of D. rotundus geographic distribution according to species' records between 1901 and 2019. Nevertheless, high uncertainty was detected regarding the predictability of D. rotundus environmental suitability across the United States-Mexico border and in the Andes Mountains of Chile. The overall modeling efforts did, however, reveal a northward distributional shift of the rabies reservoir as a likely response to climate change. Together, studies contained in this thesis provide empirical, retrospective evidence that demonstrates the effects of climate change on the increased risk of disease transmission at the human-wildlife interface. / Master of Science / Climate change is understood as the change in global or regional climate patterns, including variations of temperature and humidity factors beyond normal ranges, mostly attributed to increased levels of atmospheric carbon dioxide. Climate change is expected to influence many biological systems and presents an imminent threat to almost all organisms and geographic areas across the globe. Previous studies suggest that climate change will increase the burden of infectious diseases, including those originating from wildlife. This thesis aims to assess the availability of empirical evidence supporting the idea of a link between climate change and infectious diseases of wildlife origin. Chapter 2 examines recent scientific literature assessing climate change and infectious disease, and identifies biases in the diseases, species, and geographic areas commonly studied. This study found that literature generally focused on diseases transmitted by arthropods (e.g., insects, arachnids, or crustaceans) in temperate areas. There was little focus on diseases transmitted directly (e.g., via bites) or in non-temperate areas (e.g., tropics). Chapter 3 attempts to address issues detected in Chapter 2 by studying a directly-transmitted infectious disease in the tropics. More specifically, Chapter 3 assessed the impacts of climate variation from the last century on the distribution of the common vampire bat (Desmodus rotundus), which is a known rabies host in Latin America. Chapter 3 revealed that temperature variables were the largest drivers of common vampire bat distribution. Nevertheless, high uncertainty was detected regarding the vampire bat's ability to invade new areas such as the continental United States-Mexico border or the lowlands to the Andes Mountains in Chile. Together, studies contained in this thesis provide support for current and future research on the study of climate change as an amplifier for the risk of infectious diseases.
23

The Role of Hepcidin in Regulation of Iron Balance in Bats

Stasiak, Iga 17 September 2012 (has links)
Iron storage disease is a significant cause of liver disease and mortality in captive Egyptian fruit bats (Rousettus aegyptiacus). The nature of the susceptibility in this and other captive exotic species to iron storage disease is not clear. Hepcidin, a key iron regulatory hormone, is involved in the regulation of iron absorption in humans and other mammalian species and a deficiency in hepcidin has been associated with a number of genetic mutations resulting in hemochromatosis in humans. The objectives of this thesis were to identify whether there is a functional mutation in the hepcidin gene in the Egyptian fruit bat that may increase the susceptibility of this species to iron storage disease, and whether there is a functional deficiency in hepcidin gene expression in the Egyptian fruit bat in response to iron challenge. We compared the coding region of the hepcidin gene amongst several species of bats and investigated hepcidin response to intramuscular injection of iron dextran amongst three species of bats with variable susceptibility to iron storage disease; the Egyptian fruit bat, the straw-colored fruit bat (Eidolon helvum), and the common vampire bat (Desmodus rotundus). While a number of genetic differences were identified amongst species, a functional mutation that could result in decreased hepcidin activity was not identified in the Egyptian fruit bat. Bats exhibited marked variation in hepcidin gene expression, with the highest level of hepcidin response to iron challenge in the common vampire bat. While the Egyptian fruit bat exhibited significant hepcidin response to iron challenge, the magnitude of response was lower than that in the common vampire bat and lower than expected based on findings in healthy humans. The straw-colored fruit bat did not exhibit any hepcidin response despite a significant increase in iron stores, which suggests this species may have evolved an alternate mechanism for coping with excessive iron or may be more susceptible to iron overload than previously recognized. / Toronto Zoo Scholarship Fund

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