Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Fred Valdez, Jr. Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Includes vita. Includes bibliographical references: (p. 322-336).

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The purpose of this study is to determine what opportunities the public schools of the Lower Rio Grande Valley of Texas are offering to Latin-American students, how they are meeting the students' needs, and what changes, if any, could be made to adjust their curriculum to meet these needs.

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It is the purpose of this study to consider the Anglo-American child--to examine his achievement in a situation where much consideration will of necessity be given to the instructional needs peculiar to the predominating group.

Texas is the leading U.S. producer of cotton, and the U.S. is the largest international market supplier of cotton. Risks and uncertainties plague Texas cotton producers with unpredictable weather, insects, diseases, and price variability. Risk management studies have examined the risk reducing capabilities of alternative management strategies, but few have looked at the interaction of using several strategies in different combinations. The research in this study focuses on managing risk faced by cotton farmers in Texas using irrigation, put options, and yield insurance. The primary objective was to analyze the interactions of irrigation, put options, and yield insurance as risk management strategies on the economic viability of a 1,000 acre cotton farm in the Lower Rio Grande Valley (LRGV) of Texas. The secondary objective was to determine the best combination of these strategies for decision makers with alternative preferences for risk aversion. Stochastic values for yields and prices were used in simulating a whole-farm financial statement for a 1000 acre furrow irrigated cotton farm in the LRGV with three types of risk management strategies. Net returns were simulated using a multivariate empirical distribution for 16 risk management scenarios. The scenarios were ranked across a range of risk aversion levels using stochastic efficiency with respect to a function. Analyses for risk averse decision makers showed that multiple irrigations are preferred, and that yield insurance is strongly preferred at lower irrigation levels. The benefits to purchasing put options increase with yields, so they are more beneficial when higher yields are expected from applying more irrigation applications.

The Lower Rio Grande Valley (LRGV) of Texas is an ecologically diverse region in the United States and marks the northernmost extension for many tropical species of plants and animals. Since the early 1900s, 95% of the native Tamaulipan brushlands have been cleared due to agricultural practices and urban development. The plain chachalaca (Ortalis vetula) is a medium sized bird endemic to the native brushlands of the LRGV. In 2003, I trapped and radio-tagged 29 birds (16 males, 13 females) to evaluate the effects of fragmentation on the population dynamics (i.e., survival, mortality, and movements) of this brushland species. My study objectives were to estimate (1) seasonal survival of chachalacas by sex, and (2) ranges, core areas, and movements using radio telemetry. Mammalian predation (43%, n = 6) and unknown (43%, n = 6) deaths accounted for the majority of mortality observed. I found no difference (P > 0.05) in estimated 8-month survival (December 2003-July 2004) between males (S = 0.364, SE = 0.132) and females (S = 0.405, SE = 0.153). In comparing seasonal survival for all birds (males and females combined), I observed a difference (P < 0.05) in survival between the nesting (S = 0.414, SE = 0.103) and breeding seasons (S = 0.917, SE = 0.079). Female ranges (x‾ = 117 ha, range = 42–177 ha) and core areas (x‾ = 23 ha, range = 5–46 ha) during the nesting season were larger than male ranges (x‾ = 41 ha, range = 31–46 ha) and core areas (x‾ =10 ha, range = 7–14 ha) during the same period. During the breeding season, female ranges (x‾ = 59 ha, range = 10–188 ha) and core areas (x‾ = 9 ha, range = 2–33 ha) were similar to male ranges (x‾ = 48 ha, range = 4–130 ha) and core areas (x‾ = 9 ha, range = 1–23 ha). Mean distances between seasons were similar for both sexes (females, nesting, x‾ = 486, breeding, x‾ = 345; males, nesting, x‾ = 184, breeding, x‾ = 292), though females distances generally were greater. Dispersal defined as movement off the Santa Ana National Wildlife Refuge was observed for 3 birds. In 2 cases, a radio-tagged female and male were observed crossing the Rio Grande River (approximately 100-m wide) to habitat in Mexico. Study results suggested mammalian predation may limit the growth of chachalaca populations. Though land use changes such as agricultural uses may not directly limit chachalaca populations in providing cover and food, concentration of populations in remnant native brushlands may serve as ecological “sinks” to the species. Greater range and movement data observed in my study may be attributed to suboptimal habitat (i.e., increased fragmentation) for plain chachalacas.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.