Five species of sympatric Vanilla (Orchidaceae) occur in the wetlands of Madre de Dios, Peru. The majority of species emanate from very different phytogeographic regions but one seems to be a previously undocumented species. All species are fully described and their habits, life histories, pollination strategies, dispersal strategies, and ecologies are detailed and discussed. Little is known concerning the vegetation communities of these upper Amazonian wetlands and this system continues to be severely understudied. Sixteen wetlands spanning over 200km of floodplain habitat were visited in order to document the local distribution of each species. This marks the most geographically extensive study of this wetland system to date and Vanilla is used as a model in order to create hypotheses concerning larger vegetation patterns in the region. Furthermore, habitat of a single, potentially commercial species is classified using satellite imagery and the conservation implications discussed.

Total and methylmercury concentrations were measured in Mississippi grass shrimp (<em>Palaemonetes kadiakensis</em>) that were collected from river, wetland, and open-water habitats in Caddo Lake, Texas. Because grass shrimp are short-lived and relatively immobile, their mercury concentrations are representative of the mercury levels at the location from which they are collected. The highest concentrations of mercury are in grass shrimp collected from the river and the lowest were from open-water habitats. Mercury levels in shrimp collected in the wetland are intermediate between river and open-water habitats but exhibit a large amount of variation suggesting the wetlands of Caddo Lake are quite heterogeneous and require further study to understand their spatial variation. Methylmercury is strongly correlated to total mercury and constitutes 94% of the total mercury regardless of the habitat from which they were collected. This suggests total mercury concentrations are a useful proxy for predicting methylmercury concentrations.

Nanostructured materials continue to attract attention because of their new and interesting properties, which are very different from their macrostructured equivalents. Since the size of grain and surface differs, a better understanding of the microstructure, the mechanism of formation, and methods of controlling surface properties is necessary. In this study, nanostructured silicon carbide has been produced from the solid-solid reaction of a mixture of silicon nanopowder and carbon multiwalled nanotubes (MWNT) sintered by induction. A study of the reaction rate at different temperatures has yielded a value for the activation energy of 254 ± 36 kJ/mol, and has led to the conclusion that the reaction is diffusion-controlled. A second method produced pure silicon carbide nanowires using a procedure which kept the solid reactants, silicon powder and MWNT, separated while sintering at a constant temperature of 1200◦C. Silicon in the vapor-phase reacted at the surface of the MWNTs followed by diffusion of both precursors through the product phase boundary. The reaction time was varied, and a morphological study has been done describing changes in shape and size as a function of time. The initial reaction produced a layer of SiC providing the outer shell of coaxial structures with carbon nanotubes inside. As Si and C diffused through the product phase to react at the interface, the tube became filled with SiC to form solid SiC nanowires, and the outer diameter of the nanowires grew continuously as reaction time increased. After long sintering times, growth continued in two dimensions, fusing nanowires together into planar structures. In addition, the precursor form of carbon was varied, and nanowires produced by two different types of nanotubes have been studied. The produced SiC nanowires show cubic crystal structure. After a few hours of sintering, stacking faults began to occur inside the wires, and the frequency of occurrence of the stacking faults increased as reaction time increased. Long sintering times from 26 to 64 hours produced enough stacking faults to manifest as a 2H peak in x-ray diffractograms. HRTEM and HRSEM showed evidence of an amorphous phase at the surface about 2 to 3 nm thick.

THE CHARACTER OF COAL-BEARING STRATA OF THE FERRON SANDSTONE (CRETACEOUS), EAST-CENTRAL UTAH The Ferron Sandstone (Cretaceous) of east-central Utah is a significant reservoir rock for a prolific gas play in the region. Three facies are present in core of the sandstone. Coarsening upward sequences of laminated shale and siltstone that grade upward to horizontally laminated fine-grained sandstones make up the delta front. Coal, carbonaceous shale and oyster coquina make up the delta plain environment, and massive sandstone bodies represent a shallow shelf environment. Ichnofacies seen in core range from high energy beach sandstone (Skolithos) to low energy, mud-rich marsh deposits (Thalassinoides). Several zones within the sandstone have high porosity, but most of the primary porosity has been filled by calcite cement. Partial dissolution of the calcite cement has created porous zones. However, the cement has restricted pore throats making the effective porosity low.

Depression has a devastating impact on both the individual and society. Depression is usually treated with a chronic antidepressant, resulting in behavior modification. The mechanisms that cause depression are unknown and the resulting behavioral response seen with antidepressant therapy is also poorly understood. Animal models have shown that one response induced by chronic antidepressant therapy is increased neurogenesis within the dentate gyrus of the hippocampus. (Malberg, 2004). It has been hypothesized that the enhanced neurogenesis is a causative factor in antidepressant-mediated behavioral modification, but has not been well proven. Using a two-by-two experimental design and with a more effective tool than previously used in other studies to block neurogenesis, we tested the relationship between enhanced neurogenesis, i.e. the number of new neurons in the dentate gyrus, in response to chronic antidepressant treatment and the behavioral modifications that take place. Our findings suggest that blocking neurogenesis results in increased learning over control animals.

Araceae family comprises 106 genera and almost 3500 species with a nearly world-wide distribution. About 60% of the Araceae species of the world occur in the Neotropics. Even though recent research in Peru has resulted in a dramatic increase of species, the family is still poorly known. One of the major gaps in our knowledge of the diversity and distribution of Araceae is in the Andes-Amazon region of southeastern Peru. The analysis of existing and new collections helped better characterize the diversity and distribution of Araceae in the region. A total of 1048 field collections, including the ones conducted in this study, have yielded 161 species in 22 genera. We report additions to the Araceae flora of southeastern Peru including 14 endemic species. The area of Cusco holds the highest number of endemic species. Other areas for further research in the distribution and diversity of Araceae are proposed in this study.

This thesis examines the procedures and relative merits of some of the methods available for sediment budgeting focusing on the middle Trinity River, Texas. These methods included analysis of historical sediment and flow gaging station data, GIS digitization of sand bars, and field measurement of sand bar storage. The gaging station data indicated the middle Trinity River acts as a sediment source for the lower reaches. To understand where this surplus of sediment is coming from, it was necessary to consider tributary loading data, GIS analysis of Natural Resource Inventory (NRI) erosion rates, and lake survey data. This information showed that sediment storage along the Trinity River is extensive. We infer that sediment in the middle Trinity River is most likely being sourced from the reworking of sediment as the river moves across the floodplain in addition to the river channel itself.

The Gray Sandstone series (lower Buckner Formation, Upper Jurassic) in Cotton Valley field, northern Louisiana, consists of discrete sandstone lobes of limited lateral extent. The continuity of the Gray Sandstone across the area is due to the overlapping of discrete sandstone lenses. Net sand isochore maps show the Gray Sandstone to be a series of dip-parallel lobes clustered at the mouth of a feeder channel that bifurcates downdip. Individual lobes may be amalgamated with adjacent lobes and contain sedimentary features and ichnological fabrics most commonly associated with episodic strom deposits. Production from the Gray Sandstone series in Cotton Valley field comes from over a large, doubly plunging, salt-induced anticline. Production occurs over the crest and on the flanks of the structure.

Since 1990 Ecotourism has been growing, on average, 25-30% per year worldwide. This is especially important for developing countries where tourism is the major foreign exchange earner. Tourism is Costa Rica's largest industry, earning the country 1.9 billion dollars per year. To maintain this industry in a sustainable way, Costa Rica has adopted a certification process to rate hotels and tour operators called the Certification for Sustainable Tourism (CST.) This program looks at four main criteria: physical and biological parameters, infrastructure and services, external clients and the socio-economic environment to accurately assess the sustainability in Costa Rica. One of the most biologically diverse and frequently visited destinations in Costa Rica is the Monteverde Zone. Since the very survival of this area is dependent on how well it is being preserved, Monteverde is an important case study. This paper looks at the three aspects of new conservation: (i) empowerment, (ii) participation and (iii) sustainability to measure the success of the CST program at three hotels in the Monteverde Zone, Costa Rica.

The major facies in the EOG Gordon SWD core are mudstone, siltstone, phosphatic layers, shell layers, and a carbonate concretion. Facies C2 is a sandy phosphate layer, which concentrated organic matter. Facies C2 is traceable and can be interpreted as a condensed section associated with a maximum flooding surface. The uranium in phosphate and organic matter cause a high gamma-ray reading in this interval. High TOC and high gamma-ray response occur in the same intervals of the core, but their magnitudes are not directly related. The Barnett deposition was sourced from the north and was a function of eustacy. The middle and upper unit were sourced from the Ouachita fold-thrust belt. The siltstone facies, common in these intervals, is rich in sponge spicules and is sourced from a reef growing on the thrust belt. A change in relative sea level in these two intervals is due to both eustacy and tectonics.