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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.
1

The Effect of Precipitation on the Spread of Mosquito-Borne Diseases: A Case Study of Florida Counties

Osbourne, Marvin 01 January 2015 (has links)
The state of Florida is the third most populous state in the United States of America, with six (6) of its metropolitan areas dubbed as the fastest growing in the entire country. A mosquito bite may mean the transmission of a virus or disease which might be fatal. Hence, there is a need for the state to control mosquitoes through the various Departments of Mosquito Control in each of its sixty-seven (67) counties. Six locally acquired mosquito-borne viruses which affect humans and animals in the state of Florida were considered. This thesis used statistical methods to examine data for rainfall, population estimate, as well as, the data on six (6) arboviruses, over the course of thirteen (13) years, namely 2002 to 2014. The first hypothesis that was tested, was that greater precipitation increased the likelihood of a greater number of arbovirus cases. It was important to also examine the relationship that this growing human population had with mosquito-borne diseases, and so the second hypothesis that was tested, was that, an increase in the human population would increase the likelihood of a greater number of arbovirus cases. Subsequently, an analysis was done for eleven (11) of Florida*s 67 counties with the greatest cumulative occurrence of human and animal arbovirus cases combined. Of the eleven counties, seven exhibited a weak associated between the size of the human population and the spread of animal and human arbovirus cases; three exhibited a somewhat moderate association; and one – Osceola County – had a strong negative association. This indicated that, as the size of the human population increased in Osceola County, the combined number of human and animal arbovirus cases decreased, which refuted the second hypothesis of this thesis. A linear regression model for the data for Osceola County was derived and that model was used to simulate what will occur in future years with the use of population projection data. In each simulated year, the number of combined human and arbovirus cases was negative. This prediction meant that, as the projected population increased from year to year, then the number of cases should be zero in each year. The reliability of these predictions are questionable, since Osceola County does not exist in a vacuum and it cannot be isolated from the surrounding counties which may be experiencing an outbreak of arboviruses.
2

Images radar des précipitations et durée dhumectation simulée pour lévaluation des risques potentiels dinfection du blé dhiver par la septoriose/Weather-Radar Rainfall Measurement and Simulated Surface Wetness Duration for Septoria Leaf Blotch Risk Assessment

Mahtour, Abdeslam 10 November 2010 (has links)
Lhumectation des surfaces végétales, due principalement aux précipitations sous forme de pluie ou de rosée, joue un rôle déterminant lors de la phase de contamination des plantes par de nombreux agents phytopathogènes. La connaissance de la pluie et de la rosée constitue un élément fondamental pour létude et la compréhension du fonctionnement des modèles de simulation des épidémies et des systèmes d'avertissements agricoles. Lobjectif de cette recherche est de contribuer à lamélioration du système davertissement des principales maladies cryptogamiques affectant le blé dhiver au sud de Belgique et au G-D de Luxembourg. Notre démarche a consisté, dans un premier temps à évaluer les potentialités du radar météorologique de Wideumont. Nous avons décrit son fonctionnement général ainsi que son principe de mesure et nous avons détaillé les différentes sources derreur qui affectent les estimations de précipitations dérivées des observations radar. Les mesures radar sont moins précises que les mesures de précipitations par des pluviomètres. Néanmoins, le radar permet dobserver en temps réel les précipitations sur un large domaine avec une très bonne résolution spatiale et temporelle. La comparaison quantitative et qualitative des précipitations mesurées au sol avec celles estimées par le radar a été faite sur une période de trois ans (2003, 2004 et 2005). Les résultats de la validation des cumuls mensuels font apparaître que le radar a tendance à sous-estimer les précipitations. Lerreur calculée pour lensemble des stations varie entre -50% et +12%. La validation qualitative du radar a été réalisée sur des occurrences de cumuls horaires. Les indices calculés à partir des tables de contingence donnent des valeurs de POD (Probability Of Detection) entre 0.44 et 0.80 durant la période étudiée. Limpact des estimations radar sur les périodes dinfection de Septoria tritici simulées par PROCULTURE a été évalué durant trois saisons culturales (2003, 2004 et 2005) par comparaison entre les données de sortie du modèle (alimenté par des estimations radar de précipitations horaires) et les estimations visuelles du développement des symptômes de la maladie sur les trois dernières feuilles. Les outputs de PROCULTURE via les données radar ont montré un grand accord entre la simulation et lobservation. Le radar météorologique devrait dès lors être bénéfique pour des régions où le réseau des pluviomètres est inexistant (ou moins dense) et où lincidence de la septoriose est importante. Dans un deuxième temps, sur base dune recherche bibliographique, un modèle dhumectation a été choisi. Le modèle sélectionné, appelé SWEB, se base sur le bilan énergétique et le bilan hydrique. Il simule la durée dhumectation due à la pluie et à la rosée sur lensemble du couvert végétal à partir des données issues des stations agrométéorologiques. Le modèle a été ensuite testé et validé sur différentes variétés de blé dhiver. Les données de sortie du modèle ont été comparées statistiquement aux mesures des capteurs (préalablement calibrés) et aux données dobservation obtenues sur des parcelles expérimentales et au champ durant les saisons culturales 2006 et 2007. Sur base des résultats obtenus, le modèle SWEB semble sous-estimer la durée dhumectation et plus particulièrement pour les événements de la fin dhumectation (dryoff). Lerreur moyenne en général est inférieure à 90 minutes. Dans un troisième temps, afin dobtenir une relation entre les périodes dhumectation et le développement de la septoriose sur les trois dernières feuilles, les périodes dhumectation simulées par SWEB ont été comparées dune part aux périodes dinfection de Septoria tritici simulées par PROCULTURE et dautre part aux estimations visuelles. Le modèle de la durée dhumectation simule avec succès des périodes dhumectations, dues à la fois à la rosée et à la pluie, qui ont déclenché linfection de la septoriose observée sur des parcelles expérimentales. Une durée minimale dhumectation favorable à linfection des feuilles de blé par Septoria tritici a été déterminée. Il est donc désormais nécessaire délaborer un système opérationnel intégrant le radar météorologique, le modèle de la durée dhumectation et le modèle épidémiologique. Notre travail a permis dacquérir via lanalyse des données agrométéorologiques et des données phytopathologiques, les connaissances nécessaires à lélaboration dun tel système et de participer ainsi à lamélioration des modèles davertissements existants. En effet, nous avons analysé les avantages et les limites du système radar comme données dentrée aux modèles et son aptitude dans la spatialisation des données. Nous avons également testé le modèle dhumectation pour la détermination des périodes dinfection nécessaires au développement de la septoriose. Dans une perspective dune meilleure opérationnalisation du système, lapproche envisagée pourrait facilement être intégrée dans le système existant pour la simulation dautres maladies comme les rouilles, loïdium et la fusariose à léchelle régionale. En définitive, ce travail aura prouvé une fois de plus lintérêt du "mariage" entre lagrométéorologie et la phytopathologie. [en] Summary - Weather-Radar Rainfall Measurement and Simulated Surface Wetness Duration for Septoria Leaf Blotch Risk Assessment. The persistence of free moisture on leaves, mainly as a result of precipitation in the form of rainfall or dew, plays a major role during the process of plant infection by most fungal pathogens. Acquiring rainfall and leaf moisture information is needed for accurate and reliable disease prediction and management. The objective of this research is to contribute to improve forecasting Septoria leaf blotch and other fungal pathogens on winter wheat in Belgium and Luxembourg./In the first part of this work, the potential of weather-radar rainfall estimates for plant disease forecasting is discussed. At first step, we focused on assessing the accuracy and limitations of radar-derived precipitation estimates, compared with rain-gauge data. In a second step, the Septoria leaf blotch prediction model PROCULTURE was used to assess the impact on the simulated infection rate of using, as input data, rainfall estimated by radar instead of rain gauge measurements. When comparing infection events simulated by PROCULTURE using radar-derived estimates and reference rain gauge measurements, the probability of detection (POD) of infection events was high (0.83 on average), and the false alarm ratio (FAR) of infection events was not negligible (0.24 on average). FAR decreased to 0 and POD increased (0.85 on average) for most stations, when the model outputs for both datasets were compared against visual observations of Septoria leaf blotch symptoms. Analysis of 148 infection events observed over three years at four locations showed no significant difference in the number of simulated infection events using either radar assessments or gauge measurements. This suggests that, for a given location, radar estimates are just as reliable for predicting infection events as rain gauges. As radar is able to estimate rainfall occurrence over a continuous space, unlike weather station networks that do observations at only a limited number of points, it has the great advantage of being able to predict the risk of infection at each point within an area of interest with an accuracy equivalent to rain gauge observations. This gives radar an important advantage that could significantly improve existing warning systems. In the second part, a physical model based on the energy balance, known as the Surface Wetness Energy Balance (SWEB), was applied for the simulation of Surface Wetness Duration (SWD) on winter wheat canopy. The model, developed in the United States on grapes canopies, was adapted for the winter wheat cultivars and was applied for use with agrometeorological data easily available from standard weather stations and weather-radar rainfall estimates. The SWEB model simulates surface wetness duration for both dew and rain events. The model was validated with data measured by sensors and with visual observations of SWD conducted in experimental plots during two cropping seasons in 2006 and 2007. The wetness was observed visually by assessing the presence or absence of surface water on leaves. Based on the results, the SWEB model appeared to underestimate surface wetness duration and especially for the dry-off events when compared statistically to visual observations. The error, on average, is generally less than 90 minutes. In order to establish a relationship between the surface wetness periods and Septoria leaf blotch development risk on the top three leaves, the SWEB model SWD outputs were compared with the number of hours of high probability of infection simulated by PROCULTURE as well as with visual plant diseases observations. A minimal surface wetness duration of favourable infection conditions for Septoria tritici was established. It is now required to develop an operational system that would integrate weather radar, surface wetness duration and foliar epidemic model. In this work, we have analyzed the advantages and limitations of the radar system as input to models and its ability for spatial interpolation of rainfall. We also tested the model for the determination of surface wetness periods required for Septoria Leaf Blotch Risk development. The proposed approach could be integrated in the existing system. Finally this approach shows once more the "happy marriage" between agrometeorology and plant disease management.
3

Produção e consumo de frutos zoocóricos em dois fragmentos florestais do oeste do Rio Grande do Norte, Brasil. / Production and consumption of fruits zoochorous in two forest fragments in the west of Rio Grande do Norte, Brazil.

Torquato, Jânio Lopes 26 February 2015 (has links)
Made available in DSpace on 2016-08-31T13:19:25Z (GMT). No. of bitstreams: 1 JanioLT_DISSERT.pdf: 2434239 bytes, checksum: 49254b87885eb32f1754da2c513afabd (MD5) Previous issue date: 2015-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The availability of fleshy fruits in forest fragments is essential for the survival of many animal species. The disadvantage of small fragments to native wildlife is the decrease in fleshy fruits availability, especially in the period of food shortage. Together with the food shortage period there is an environmental factor, rainfall, which directly influences the production of fruits zoochorous, and consequently in the diet and survival of fauna. The goal of this study was to compare the production and consumption of fruits zoochorous in forest fragments in the western of Rio Grande do Norte state. The study took place in two forest fragments: Parque Nacional da Furna Feia PARNA Furna Feia (8.517ha) and Trilha dos Polinizadores TRIPOL (26ha), from June 2013 to July 2014. The data collection was done every 15 days in pre-established trails in forest fragments. The counting of ripe fruit zoochorous in forest fragments was done in two ways: estimation and absolute. The diet of the animals was analyzed by feces collected on the trails and screened in the ECOMOL/UFERSA lab. The frugivorous animals were recorded with the help of the trap camera and some Caatinga native fruit were placed in front camera. The data of rainfall were obtained from the National Institute of Meteorology INMET. In total, 270 individuals were recorded fruiting, 13 zoochorous specie and nine botanical families. Considering the 13 species recorded zoochorous, only 11 were fruitful, 10 in the rainy season. The accumulated abundance of ripe fruit registered at the TRIPOL (n = 36,494; 15.7 fruits/m²) was higher than in PARNA Furna Feia (n = 27 168; 3.7 fruits/m²). At TRIPOL, the species which produced more fruits were: Spondias tuberosa, Ziziphus joazeiro, Lantana camara, Tournefortia volubilis and Phoradendron affine. At PARNA Furna Feia, the species which produced more fruits were: Ziziphus joazeiro and Commiphora leptophloeos. The relationship between the abundance of zoochorous fruit and the precipitation was significant at TRIPOL (rs = 0.5438, p = 0.0041), but there was no significant relation at PARNA Furna Feia (rs = 0.1973, p = 0.3337). There was no significant relation between the abundance of zoochorous fruit and the number of seeds registered in the feces. In them, 666 seeds were registered at TRIPOL and 4.281 seeds at PARNA Furna Feia. Considering the total number of seed found in the feces, the species T. volubilis and Sideroxylon obtusifolium represented 55,2% and 72,2% of total seed, respectively in each fragment analyzes. The animals recorded by the trap cameras consuming the fruit-baits in forest fragments were Tupinambis merianae, Ameiva ameiva, Turdus rufiventris, Mimus saturninus, Coereba flaveola, Cyanocorax cyanopogon, Cerdocyon thous and Callithrix jacchus. Cerdocyon thous and Cyanocorax cyanopogon were the two species which most consumed the fruit-baits of Copernicia prunifera and Cereus jamacaru, respectively. The species C. thous and C. cyanopogon can be important seed dispersers in forest fragments of the Caatinga. The fruits of species T. volubilis and S. obtusifolium are important food source for fauna, especially S. obtusifolium which offers ripe fruit during fleshy fruit shortage period / A disponibilidade de frutos carnosos em fragmentos florestais é essencial para a sobrevivência de diversas espécies da fauna. A desvantagem dos pequenos fragmentos para a fauna nativa é a diminuição da abundância de frutos carnosos ao longo do tempo, principalmente no período de escassez de alimentos. Junto ao período de escassez de alimento há um fator ambiental, a precipitação pluviométrica, que influencia diretamente na produção de frutos de plantas zoocóricas e, consequentemente, na dieta e sobrevivência da fauna. O objetivo deste estudo foi comparar a produção e o consumo de frutos zoocóricos em fragmentos florestais no oeste potiguar nordestino. O estudo foi realizado em dois fragmentos florestais: Parque Nacional da Furna Feia PARNA Furna Feia (8.517ha) e a Trilha dos Polinizadores TRIPOL (26ha), durante junho de 2013 a julho de 2014. A coleta de dados foi realizada a cada 15 dias em trilhas pré-estabelecidas nos fragmentos florestais. A contagem dos frutos zoocóricos maduros nos fragmentos florestais foi realizada de duas formas: estimativa e absoluta. A dieta dos animais foi analisada por meio de fezes coletadas nas trilhas e triadas no laboratório ECOMOL/UFERSA. Os animais frugívoros foram registrados com o auxílio da câmera armadilha utilizando frutos de espécies nativas da Caatinga como isca. Os dados de precipitação pluviométrica foram obtidos no Instituto Nacional de Meteorologia INMET. No total foram registrados 270 indivíduos frutificando, sendo 13 espécies zoocóricas e nove famílias botânicas. Das 13 espécies zoocóricas foram registradas 11 que produziram frutos, sendo que 10 frutificaram no período chuvoso. A abundância absoluta acumulada de frutos maduros registrados na TRIPOL (n = 36.494; 15,7 frutos/m²) foi maior do que no PARNA Furna Feia (n = 27.168; 3,7 frutos/m²). Na TRIPOL, as espécies que produziram mais frutos foram: Spondias tuberosa, Ziziphus joazeiro, Lantana camara, Tournefortia volubilis e Phoradendron affine. No PARNA Furna Feia, as espécies que produziram mais frutos foram: Ziziphus joazeiro e Commiphora leptophloeos. A relação entre a abundância de frutos zoocóricos e a precipitação pluviométrica foi significativa na TRIPOL (rs = 0,5438; p = 0,0041), mas não houve relação significativa no PARNA Furna Feia (rs = 0,1973; p = 0,3337). Não houve relação significativa entre a abundância de frutos zoocóricos e o número de sementes registradas nas fezes. No total de amostras de fezes coletadas e analisadas foram registradas 666 sementes na TRIPOL e 4.281 sementes no PARNA Furna Feia. Do total de sementes encontradas nas fezes, as espécies T. volubilis e Sideroxylon obtusifolium representaram 55,2% e 72,2% do total de sementes, respectivamente. Os animais registrados pelas câmeras armadilha consumindo os frutos iscas nos fragmentos floretais foram: Tupinambis merianae, Ameiva ameiva, Turdus rufiventris, Mimus saturninus, Coereba flaveola, Cyanocorax cyanopogon, Cerdocyon thous e Callithrix jacchus. A C. thous e a C. cyanopogon foram as duas espécies que mais consumiram os frutos isca da Copernicia prunifera e do Cereus jamacaru, respectivamente. As espécies C. thous e o C. cyanopogon podem ser importantes dispersores de sementes em fragmentos florestais. Os frutos das espécies T. volubilis e S. obtusifolium são importantes fonte de alimento para a fauna em fragmentos florestais de Caatinga, com destaque para S. obtusifolium que disponibiliza frutos maduros durante o período de escassez de frutos carnosos

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