The purpose of this project is to assess the instream flow conditions of the Brazos River from the perspective of determining the levels necessary to maintain the integrity of the river channel as a recreational and ecological resource. The area of this study is the reach of the Brazos River between Lake Granbury and Lake Whitney, located ~48 km southwest of Fort Worth, Texas. Based on changes observed in the channel cross-sectional profiles and calculation of volumes of sediment stored in channel bars, a gauge height of ~ 5.5 6.3 (~314 650 cfs) is the minimal optimal range that would support recreational use. The estimated annual sediment yield for the Brazos River is ~10.5K tons. The channel bars at the Tres Rios confluence and FM 200 bridge store ~249K tons of sediment, indicating that in this reach of the river, the Brazos is a storage dominated system.

A study of orchids was carried out in a cloud forest in southeastern Peru, in the department of Cusco, between September 2005 and August 2006. A systematic collection found 239 different morphospecies of orchids which was compared to those found at two similar areas, Manu National Park and Machu Picchu Historical Society. A set of 47 plots were set up and monitored for orchid diversity, abundance, and phenology of the area. Based on habit (epiphytic or terrestrial), the number of species varied among habitats. Orchids were shown to be flowering at all times of the year with some species being rarer. Flowering times of the orchids were maximized in times of high precipitation levels (February). Recommendations are made for future research, including study length and design. A potential protocol for orchid conservation is also described, with attention to size of a reserve to include multiple variables.

The Sapotaceae is a highly diverse and abundant family of large tropical trees that have a significant ecological importance in lowland tropical forests worldwide. The goal of this study is to inventory Sapotaceae species of the Los Amigos River watershed, and investigate local variations of species diversity and distribution. 1087 individual trees sampled in 75 0.1-hectare Gentry transect units across upland and floodplain forests show this family of trees to be the third most species rich and fourth most abundant across the study landscape. A total of 95 species and five subspecies of Sapotaceae are reported with four new species described for the flora of Peru and ten new to Madre de Dios. Statistical and similarity analyses conclude higher levels of diversity and abundance for the Sapotaceae communities of upland or terra firme forests.

Past research on the emotions associated with attitudes has investigated the extent to which specific types of emotions lead to actions (Seitz, Lord & Taylor, 2007). The present research extends this past research by showing that emotions engender a functional specificity with consequences for attitude-behavior consistency. In addition, the present research extends Attitude Representation Theory (Lord & Lepper, 1999) by showing that some emotions included in the attitude objects representation may involve specific action tendencies (reward/punish; approach/avoid) that result in consequences for attitude-behavior consistency. Experiment 1 employed an emotion manipulation. Participants were primed to associate either the emotion fear or the emotion anger with their attitudes. Experiment 2 borrowed from the literature on prejudice (Cottrell & Neuberg, 2005), using social groups known to elicit specific emotions (African Americans: Fear, Activist Feminists: Anger). The central hypothesis--that specific emotions associated with an attitude target can elicit specific behaviors and in turn result in better attitude-behavior consistency--was partially supported. In Experiment 1, participants primed to associate fear with Mexican Americans later reported relatively high levels of fear and concerns about personal safety, as well as relatively high levels of attitude-behavior consistency on approach-avoidance measures. Those primed to associate anger with Mexican Americans did not do so, but they did display relatively high levels of attitude-behavior consistency on reward-punish measures. Experiment 2 replicated earlier findings that people associate more fear and safety concerns with African Americans, but more anger and threats to their rights with Activist Feminists. They also displayed marginally higher attitude-behavior consistency with Activist Feminists than African Americans on reward-punish than approach-avoidance measures, although the attitude-behavior consistency results were not supported for behaviors toward African Americans.

Lentic community structure varies across a size gradient of ponds and lakes with physical factors, such as pond drying, and biotic factors, such as fish predation, determining the species assemblage. To test these concepts, I studied the effects of pond drying and consequent fish loss on crustacean zooplankton across a gradient of pond sizes in a Texas grassland following an exceptional drought where smaller ponds dried and lost their fish communities. After rains filled ponds in March, crustacean zooplankton were sampled in 20 temporary and 18 permanent ponds in April. Compared to permanent ponds, temporary ponds had fewer zooplankton species, more similar community assemblages and larger individual zooplankton. Thus, pond size mediated whether ponds dried during a drought, and drying determined the presence and absence of fish and its secondary trophic-level effects on zooplankton community structure.

A dry-etch spark ablation method was used to produce porous silica (SiO2/Si) and calcium disilicide (CaSi2/Si) layers on silicon (Si) surfaces for the electrochemical growth of apatitic phosphates (CaP). Both SiO2/Si and CaSi2/Si composite electrodes readily calcify in vitro under the application of a small electric potential, and with proper treatment the electrodeposition of CaP is localized to the sparked areas. In addition to increasing the local concentration of Ca2+, interfacial layers of CaSi2 on Si exhibit exceptional site-selectivity towards CaP formation under bias due to the difference in conductivity between Si and CaSi2. This work also describes routes to surface modification of calcified composite electrodes with medicinally relevant compounds. To assess the suitability of this material as an antibiotic delivery platform, release of norfloxacin was also monitored as a function of time. Mechanistic insights regarding biomineralization of CaSi2/Si layers on Si surfaces under zero bias were derived from an analysis of film growth morphology and chemical composition after various soaking periods in standard SBF. Changes in CaSi2 calcification behavior as a function of reaction temperature and pH, SBF concentration, and various surface modification processes were also employed for this purpose. The incorporation of CaSi2 grains within a polycaprolactone (PCL) framework results in bioactive and biodegradable scaffolds which may be used in bone tissue regeneration. Porous PCL scaffolds were prepared via a combination of salt-leaching/microemulsion methods. To provide markedly different structural environments for the inorganic phase, calcium disilicide powder was either added to a mixed-composition porogen during a given scaffolds preparation, or alternatively added to pre-formed scaffolds. Selective fluorescent labeling, SEM, and EDX were employed to assess scaffold calcification in vitro. A separate part of this work deals with rare earth-doped Si nanocrystals. Several selective surface modification reactions with inorganic capping layers comprised of either aluminum or zinc oxide were analyzed in an attempt to improve the photoluminescence (PL) efficiency of these nanocrystals by reducing interfacial defect density. It is shown that coating Er/Si-NCs with aluminum oxide via kinetically controlled chemical reaction doubles the PL efficiency. Zinc oxide, deposited under thermodynamic control, improves the PL by a factor of four.

If attitudes can be altered by memories of past actions, then such changes should occur even when the memories are false or unlikely. Also, these memories should affect not just what people say, but what they do. Participants wrote hypothetical accounts of taking previously denied positive actions toward either gay men or former mental patients. One week later, they chose a seat on a bench with either a gay man or a former mental patient. Participants chose seats closer to the type of person toward whom they had imagined taking positive actions, but did so only when they remembered actually taking one or more of those actions. The results contribute to understanding how past actions affect current attitudes and behaviors.

The work developed in this dissertation consists in the development of new methodologies for the preparation of H-phosphinic acid derivatives and their P-chiral counterparts. Special emphasis is given to the role of H-phosphinates as useful synthons for organophosphorus compounds via tandem processes. A review of the most relevant literature in terms of the preparation methodologies and reactivity of H-phosphinic acid derivatives is provided in Chapter I. The following chapter describes the addition of hypophosphorous compounds to unsaturated substrates in presence of metal-catalysts. The mechanism, regioselectivity on alkynes, and reactivity of substituted alkenes, allenes, allenols, and 1,3-dienes as substrates in a palladium-catalyzed hydrophosphinylation was investigated. A novel alkyne hydrophosphinylation catalyzed by nickel chloride or its hydrate in the absence of added ligand was discovered and exploited in the synthesis of various important organophosphorus compounds. The third chapter details a tandem esterification - cross-coupling reaction of alkyl phosphinates with aryl, heteroaryl, alkenyl, and benzylic halides and triflates. Thus the reaction of the electrophilic substrate with a hypophosphorous acid salt, in the presence of a silicate, a base and the palladium catalyst provided directly a wide variety of H-phosphinates, which were not accessible previously. In the following chapter, transition metal-catalyzed reactions of hypophosphorous compounds with allylic electrophiles are disclosed. Allylic acetates, benzoates and carbonates undergo an effective cross-coupling in the presence of palladium catalysts where pure H-phosphinic acids can be isolated by a simple acidic work-up or esterified in situ to the corresponding H-phosphinate esters. Chapter V describes a palladium-catalyzed dehydrative allylation of hypophosphorous acid with allylic alcohols, in the absence of additives. The next chapter focuses on P-H bond activation of H-phosphinates through catalytic allylation and oxidation strategies, which lead to disubstituted phosphinic acid and phosphonic acids, respectively. In the last chapter, desymmetrization strategies to access P-chiral H-phosphinates are reported. Two different avenues are explored: the use of chiral ligands in palladium-catalyzed reactions and the use of chiral auxiliaries by means of esterification of hypophosphorous acid with chiral alcohols, where 8-phenylmenthol provides, in a palladium-catalyzed hydrophosphinylation reaction, our best result with around 70% diastereomeric excess.

When making policy decisions regarding ecosystem management, human well being, economic gain, and proper price of natural capital must be weighed and determined. Many nations are starting to explore avenues to use ecosystem services to raise capital and aid in conservation. Payments for Ecosystem Services have influenced land management and conservation practices in Costa Rica and are providing a unique method for managing tropical landscapes and conserving areas of high biodiversity. The following case study attempted to assess a parcel of land adjacent to an existing reserve to determine the ultimate ecological and economic value of the land. The biodiversity of both the reserve and adjacent property were quantified, mapped and a cost -benefit analysis was calculated to determine economic value. The study determined, due to the lack of a standardized economic valuation method and tradable markets for ecosystem services, that an actual monetary value currently couldn't be assigned to an ecosystem.

It is well documented that changes in land use result in changes in soil properties. Costa Rica offers one of the most unique settings for studying soils and land use changes in the tropics. Once almost completely covered in forest, the country now bears the scars of colonization and development. However, Costa Rica is currently a working model of ecological protection and home to a successful eco-tourism industry. By setting aside large tracts of land for conservation, Costa Rica is a perfect location to compare changes in soil properties with changes in land use. The soils at the Texas Christian University San Ramon Tropical Research Station in Costa Rica, a private facility dedicated to conservation and research, have never been studied. In order to understand how land use changes have affected them, soil quality analyses were conducted. Soil pits in primary growth forest, secondary growth forest, and deforested land once used for cattle grazing were be dug in order to carry out a suite of soil tests. The results indicate that while bulk density will increase following deforestation and cattle trampling, soil porosity will return with forest succession. Cation exchange capacity results on the other hand indicate that soil fertility increases with the introduction of grasses in deforested areas. Cations also show a return to pre-disturbance levels with forest succession, which in this case is lower than post-disturbance levels.