Sweetpotato (Ipomoea batatas (L.) Lam) is a major food resource of much of the world. Sweetpotato production is damaging to the soils in which it is grown due to the nature of production and the condition the soil is left to overwinter. There is potential for future regulation on the production of sweetpotato as related to runoff and nonpoint source pollution as the sediment from runoff erosion is easy to pinpoint in nearby waterways. Two studies were carried out to determine the effect of a reduced tillage practice and cover crops on the accumulation of nutrients in cover crops and yield of sweetpotato. The use of stale seed beds will reduce the number of tillage operations in a field and will allow earlier access to the field. Cover crops will benefit the soil with cover during rains while accumulating and recycling nutrients that may otherwise be lost and improving soil structure with the addition of organic matter.

Studies were conducted in 2004, 2005, and 2006 in south Texas to evaluate fall, winter, and spring weed control for commercial rice production, study tillage intensity and herbicide rate interactions for rice production, and determine the tolerance of red rice ecotypes from Texas rice fields using selected herbicides at varying rates. A single application of any herbicide or combination of herbicides was not adequate for weed control throughout the fall, winter, and spring. Fall applications of clomazone plus flumioxazin provided consistent weed control. Addition of flumioxazin to glyphosate provided excellent winter annual grass control with winter application. A residual herbicide, coupled with the proper contact herbicide is the key to extending control. In 2006, all tillage by herbicide treatments in all studies provided ≥ 90% control of all weed species. The conventional tillage treatment with low herbicide input provided the highest rice grain yield in 2005 and 2006, though they were not significantly different from the spring stale seedbed program with medium or high herbicide input in 2006. In 2006, fall stale seedbed treatments were among the lowest in yield. A stale seedbed program may be useful, but with substantial weed pressure, increasing the intensity of herbicide applications is necessary to overcome the absence of tillage. All rice ecotypes were adequately controlled by glyphosate and only one ecotype was found to be tolerant to 2x rates of both imazethapyr and imazamox. All ecotypes were adequately controlled by 2x rates of more than two of the four herbicides which included imazethapy, imazamox, glufosinate, and glyphosate. Ecotypes from the 3.2 group, genetically similar to the ecotype TX4, appear to be the most likely to exhibit tolerance to a given herbicide. Tolerance to glufosinate was found in 70% of the group 3.2 ecotypes. Sixty percent of ecotypes from group 3.1, genetically similar to Oryza rufipogon were not adequately controlled by glufosinate.

Studies were conducted in 2004, 2005, and 2006 in south Texas to evaluate fall, winter, and spring weed control for commercial rice production, study tillage intensity and herbicide rate interactions for rice production, and determine the tolerance of red rice ecotypes from Texas rice fields using selected herbicides at varying rates. A single application of any herbicide or combination of herbicides was not adequate for weed control throughout the fall, winter, and spring. Fall applications of clomazone plus flumioxazin provided consistent weed control. Addition of flumioxazin to glyphosate provided excellent winter annual grass control with winter application. A residual herbicide, coupled with the proper contact herbicide is the key to extending control. In 2006, all tillage by herbicide treatments in all studies provided ≥ 90% control of all weed species. The conventional tillage treatment with low herbicide input provided the highest rice grain yield in 2005 and 2006, though they were not significantly different from the spring stale seedbed program with medium or high herbicide input in 2006. In 2006, fall stale seedbed treatments were among the lowest in yield. A stale seedbed program may be useful, but with substantial weed pressure, increasing the intensity of herbicide applications is necessary to overcome the absence of tillage. All rice ecotypes were adequately controlled by glyphosate and only one ecotype was found to be tolerant to 2x rates of both imazethapyr and imazamox. All ecotypes were adequately controlled by 2x rates of more than two of the four herbicides which included imazethapy, imazamox, glufosinate, and glyphosate. Ecotypes from the 3.2 group, genetically similar to the ecotype TX4, appear to be the most likely to exhibit tolerance to a given herbicide. Tolerance to glufosinate was found in 70% of the group 3.2 ecotypes. Sixty percent of ecotypes from group 3.1, genetically similar to Oryza rufipogon were not adequately controlled by glufosinate.

No description available.

No description available.

The predictability of the US-based international mutual fund returns has received renewed consideration in recent academic studies. This dissertation extends recent research by exploring the 2,479 daily return observations covering the period from January 4, 1993 to October 31, 2002 for all categories of international mutual funds. This exploration splits the sample, uses the initial sub-sample to investigate return patterns of international mutual funds and develops trading rules based on the predictable return patterns, and tests those rules on the holdout sample. The empirical findings suggest that smart investors may earn higher riskadjusted returns by following daily dynamic trading strategies. The excess returns earned by investors are statistically and economically significant, irrespective of load or no-load mutual funds and even in the presence of various exchange restrictions and regulations.

Les architectures dynamiques orientées services (D-SOA) se concentrent sur les interactions client-serveur à couplage faible, où les deux peuvent apparaître et disparaître à l’exécution. Notre objectif est de concevoir des systèmes de surveillance pour ces architectures. Comme les systèmes de surveillance classiques sont statiquement injectés dans les services surveillés, ils ne peuvent pas gérer correctement le cycle de vie des services d’exécution. En outre, quand un service est remplacé par un autre service, d’autres services peuvent toujours utiliser l’ancienne référence. Cette référence vers un service absent, lorsqu’elle est gardée en mémoire, peut induire des comportements non désirés. Cette thèse contribue à la conception d’un système de surveillance de l’utilisation des services, qui soit résistant à la dynamique de la plateforme et qui soit en mesure de faire face à l’utilisation des références obsolètes. Ce but est atteint en trois étapes. Tout d’abord, en considérant le caractère dynamique des systèmes SOA dans un environnement ouvert, nous concevons une approche de monitoring résistant au la dynamique de la plateforme. Nous identifions deux propriétés clés du système de surveillance à couplage faible: résilience à la dynamicité, c’est-à-dire qu’un moniteur d’interface et son état sont maintenus en mémoire et transférés à un nouveau service lors de la disparition d’un service utilisé, et exhaustivité́, c’est-à-dire qu’un service surveillé ne peut pas contourner les observations du moniteur. Ensuite, pour éviter l’usage de références vers des services qui ne sont plus actifs, nous proposons un service de sécurité́ côté client (SSU Layer), qui permet de traiter ce problème de manière transparente. Si un service utilisé disparaît, la couche SSU peut soit substituer le service de manière transparente, soit lever une exception pour avertir explicitement le client. Cette couche SSU est basée sur une approche transactionnelle qui vise à préserver la cohérence des services actifs. Enfin, nous proposons d’intégrer les deux approches dans un nouveau système de surveillance (NewMS). Les NewMS hérite des principes des deux systèmes précédents : la résilience à la dynamicité, l’exhaustivité et la tolérance aux fautes. Il peut dynamiquement surveiller l’utilisation de services et traiter les références obsolètes de manière transparente. Ces trois propositions sont implémentées dans la plateforme OSGi. Nous avons développé une application simple qui simule un système de réservation de place, qui est monitoré par notre système. Nous avons également proposé différentes spécifications pour ce système. Nos résultats démontrent que le coût d’observation de notre moniteur est proche du coût d’un monitor classique, ne prenant pas en compte les problématiques liées à la dynamique. / Dynamic service-oriented architectures (D-SOA) focus on loosely coupled client- server interactions where both of them can appear and disappear at runtime. Our goal is to design monitoring systems for these architectures. Since classical monitoring systems are statically injected into the monitored services, they cannot properly handle the runtime services’ lifecycle. Moreover, when a service is substituted by a new one, other services may still use the old reference. This reference is kept in memory as a stale reference which induces some forbidden behaviors. This thesis contributes to design a monitoring system with resilient dynamicity that monitors services usage and is able to deal with stale references usage. This goal is achieved in three steps. Firstly, by considering the dynamicity of SOA systems in an open environment, we design a corresponding dynamic monitoring approach. We identify two key properties of the loosely coupled monitoring system: dynamicity resilience, i.e., after the unregistration of a service, its interface monitor and its current state are kept alive in memory and transferred to a new loaded service; comprehensiveness, i.e., the implementations of the monitored interface can’t bypass the monitor observations. Secondly, to avoid stale references usage, we propose a client-side safe service usage (SSU) layer to automatically handle them. If a used service disappears, then the SSU layer can either transparently substitute it or throw an exception to the client. This SSU layer is based on a transactional approach which aims to preserve the coherence of active services. Thirdly, we propose to integrate both approaches into a new monitoring system (NewMS). The NewMS inherits the principles of both systems: dynamicity resilience, comprehensiveness and fault tolerant. It can dynamically monitor service usage and transparently handle stale references of dynamic SOA systems. All the three propositions are implemented on OSGi-based platform. We develop a simple application that simulates an Airline Reservation system, which is monitored by our monitoring systems. We also develop various automata to handle the dynamicity of the Airline Reservation system in the NewMS. Our results demonstrate that the time cost of our monitoring systems is close to one of classical monitoring systems.