Lake Malawi is the second largest lake in Africa, supporting diverse populations of endemic cichlids and supplying essential water resources to Malawi, Mozambique and Tanzania. However, population growth, rapid deforestation and intensive agriculture, especially in the southern catchments, have accelerated soil erosion during the last half century. These anthropogenically-disturbed catchments have caused rivers to transport greater sediment loads into Lake Malawi than rivers within forested catchments. Lake Malawi?s immense size and oligotrophic nature may retard detection of inputs of external contaminants. Reversing the effects of increased nutrient loading to Lake Malawi once observed would likely take generations, as the residence time of water is over 140 years. Therefore, sensitive metrics are required to assess the effects of land use change and climate variability in Lake Malawi in advance of deleterious effects. In this study, paleolimnological analyses of four sediment cores collected in 1997 and 1998 along a longitudinal transect of Lake Malawi, dated with ²¹⁰Pb analyses and analyzed for biogenic silica and sedimentary diatom assemblages, were used to create a long-term water quality dataset. These four sites span gradients of land use and latitude in order to reconstruct limnological conditions over the whole lake during the last 300 years. Paleoecological results indicate that patterns of diatom assemblage change are not uniform lake wide. Southern cores contain evidence of nutrient enrichment starting as early as ca. 1940, indicated by increased silica, carbon and nitrogen burial. By ca. 1970, increased rates of sedimentation, diatom influx and changes in diatom community composition, characterized by increased percent abundance of eutrophic diatom taxa, are attributable to accelerated enrichment by terrestrial soil erosion. The succession of diatoms in southern Lake Malawi begins with high percent abundance of <i>Aulacoseira nyassensis</i> and <i>Fragilaria africana</i>, which thrive in nutrient-rich waters, followed by a shift towards diatom taxa with reduced silica requirements by ca. 1980 (e. g. <i>Stephanodiscus nyassae, S. minutulus, S. muelleri, Cyclostephanos</i> and small <i>Nitzschia</i> species. ), a pattern comparable to the eutrophication-induced decline in silica to phosphorus ratios in Lake Victoria. In Lake Malawi, evidence of eutrophication extends to the mid lake as indicated by similar diatom assemblage changes in the sediment core from the central region. Diatom stratigraphies from the north end of the lake indicate no observable impacts of land use change on the northern basin of Lake Malawi during the past 350 years. However, a nine-meter rise in water level ca. 1860 AD appears to have resulted in elevated diatom influxes at that time comparable to the recent eutrophication-induced diatom influxes of the southern cores. The effects of this rise in water level was recorded in all three measured sites, southern, central and northern Lake Malawi, indicating lake-wide increased productivity, yet changes to the diatom community composition were imperceptible. This study shows evidence of recent cultural eutrophication altering limnological conditions with impacts to the biogeochemical cycling of silica, the available silica to phosphorus ratios and the biotic communities of a large portion of Lake Malawi. Thus, providing an early warning that proper stewardship of Lake Malawi requires effective management of land-use practices within the catchment to reduce soil erosion and avoid widespread water quality deterioration of this great lake.

Urban air pollution is responsible for high levels of morbidity and mortality in exposed populations due to its effects on cardiovascular and respiratory function. Transportation-related air pollutants account for the majority of harmful air pollution in urban areas. Forests are known to reduce air pollution through their ability to facilitate dry deposition and atmospheric gas exchange. This work characterizes the interactions between transportation air pollutants and urban forests in Hillsborough County, Florida. A highly spatially resolved passive air sampling campaign was conducted to characterize local concentrations of nitrogen oxides, benzene, toluene, ethylbenzene, and xylenes (BTEX) in Hillsborough County, Florida. Sampling locations included a proportion of densely forested urban areas in order to determine the effects of Hillsborough County's urban forest resources on localized concentrations of selected transportation pollutants. Recommended approaches for the use of urban forests as an effective air pollution mitigation technique in Hillsborough County were generated based on results from the sampling campaign. Results show mean concentrations of 2.1 parts per billion and 6.5 µg/m3 for nitrogen oxides and total BTEX, respectively. High spatial variability in pollutant concentrations across Hillsborough County was observed, with the coefficient of variation found to be 0.61 for nitrogen oxides and 0.79 for total BTEX. Higher concentrations were observed along interstate highways, in urban areas of the county, and near select point sources in rural areas. Differences in concentrations within forested areas were observed, but were not statistically significant at the 95%#37; confidence level. These results can be used to identify elements of urban design which contribute to differences in concentrations and exposures. This information can be used to create more sustainable urban designs which promote health and equity of the population.

Land surface areas, which represent approximately 30% of the Earth’s surface, contribute largely to the complexity of the climate system by exchanging water, energy, momentum, and chemical materials with the overlying atmosphere. Because of the highly heterogeneous nature of the land surface and its rapid transformation due to human activities, future climate projections are less certain on regional scales than for the globe as a whole. The work presented in this dissertation is focused on a better understanding of regional-scale land–atmosphere interactions and their impacts on climate and air quality. Specifically, I concentrate my research on three typical regions in the United States (U.S.): 1) the Central U.S. (representing transition zones between arid and wet climates); 2) the Houston metropolitan region (representing a major urban area); and 3) the eastern U.S. (representing temperate forested regions). These regions are also chosen owing to the consideration of data availability. The first study concerns the roles of vegetation phenology and groundwater dynamics in regulating evapotranspiration and precipitation over the transition zones in summer months. It is found that the warm-season precipitation in the Central U.S. is sensitive to latent heat fluxes controlled by vegetation dynamics. Groundwater enhances the persistence of soil moisture memory from rainy periods to dry periods by transferring water to upper soil layers through capillary forces. Enhancement in soil moisture facilitates vegetation persistence in dry periods, producing more evaporation to the atmosphere and resulting in enhanced precipitation, which then increases soil moisture. The second study compares the impacts of future urbanization and climate change on regional air quality. The results show that the effect of land use change on surface ozone (O3) is comparable to that of climate change, but the details differ across the domain. The third study deals with the formation and distributions of secondary organic aerosols (SOA) — a largely overlooked but potentially important component in the climate system. Under future different climate scenarios, I found that biogenic emissions — an important precursor of SOA — are expected to increase everywhere over the U.S., with the largest increase found in the southeastern U.S. and the northwestern U.S., while changes in SOA do not necessarily follow those in biogenic emissions. Other factors such as partitioning coefficients, atmospheric oxidative capability, primary organic carbon, and anthropogenic emissions also play a role in SOA formation. Direct and indirect impacts from climate change complicate the future SOA formation. / text

Assessment of long term changes in levels of biogenic substances and their amount, with regard to water yield and intensity of anthropogenic activity, in the water of different hydrological areas of Lithuania. Comparative analysis of methods for calculation of biogenic substance flows. Establishment of possibility to reduce frequency of water sampling. ATV-DVWk water quality model was for the first time in Lithuania used for forecasting of the changes in the water quality in the longitudinal profile of a river. / Biogeninių medžiagų kaitos upių vandenyje tyrimai ir įvertinimas.

No description available.

The project described in this thesis began with a broad analysis of the changes to amino acid and biogenic amine concentrations in the central nervous system (CNS) during experimental autoimmune encephalomyelitis (EAE) in mice, an animal model of Multiple Sclerosis (MS). That study identified deficits in specific neurotransmitters during EAE that I targeted pharmacologically using the antidepressant drug phenelzine. Phenelzine administration substantially influenced the concentrations of amino acids and biogenic amines in EAE mice in a manner likely to be therapeutic. In the final experiment, I treated EAE mice chronically with phenelzine; This treatment was associated with significant improvements in motor abilities compared to vehicle treated animals. In an open field, improvements were also observed in behavioural indices of depression, physical sickness and anxiety. The results of this thesis may offer new insights into the pathogenesis of EAE and MS and indicate the disease-modifying potential of phenelzine treatment in MS.

Three New Zealand marine species, hoki (Macruronus novaezealandiae), kahawai (Arripis trutta) and trevally (Pseudocaranx dentex) were used to develop model fermented fish sausage. The formulation comprised fish mince, carbohydrate, minced garlic and salt in a mass ratio of 1 (fish): 0.15: 0.05: 0.03, respectively. The carbohydrate source was cooked rice or glucose. (Endogenous lactic acid bacteria (LAB) failed to ferment rice). Folate was also added to the mixture as a factor. The mixtures were extruded into 50 mL plastic syringes, where the needle end of the barrel had been excised by lathe. The lubricated barrel was overfilled to 60 mL, capped with a layer of ParafilmTM and aluminium foil, sealed tightly by rubber band and incubated at 30°C. Over time the piston was progressively advanced to yield samples for microbiological, physical, and chemical analysis. Over 96 hours an increase in the LAB count was observed with a concomitant decrease in pH. After fermentation was complete, the samples contained around 8.77 log cfu LAB g-1 with the pH range from 4.38 to 5.08. The microbiological and pH behaviour of each species varied between preparations. Hardness, adhesiveness, springiness and cohesiveness of the treatments increased with fermentation, except for hoki. The treatments showed different colour characteristics with fermentation. The light reflectance (L* values) of the trevally and kahawai treatments increased, while the a* (redness) and b* (yellowness) values decreased. Hoki exhibited smaller colour changes except for yellowness, which increased markedly. Proteolysis, measured colorimetrically by soluble peptide bonds, was greatest for trevally. Lipid oxidation, measured by the thiobarbituric acid method, was least for hoki, notably the species with the lowest fat content. Biogenic amines, which are a general quality indicator of fermented products, increased during fermentation. The trevally treatment generated the highest concentration of amines, but these values were lower than those reported for fermented fish sausage in Southeast Asia. Notably there were no important difference between folate treatments and those without folate. The results point to commercial opportunities and further research with New Zealand marine species, especially trevally. To improve the product quality and to show geographical exclusivity, further research could be done by using starter culture, and a New Zealand staple carbohydrate source such as kumara and potato, and spices and herbs which are commonly used in New Zealand, such as rosemary, thyme and sage or specific to New Zealand, such as horopito. In addition, sensory studies should also be performed before the products could be tested in the market.

Three New Zealand marine species, hoki (Macruronus novaezealandiae), kahawai (Arripis trutta) and trevally (Pseudocaranx dentex) were used to develop model fermented fish sausage. The formulation comprised fish mince, carbohydrate, minced garlic and salt in a mass ratio of 1 (fish): 0.15: 0.05: 0.03, respectively. The carbohydrate source was cooked rice or glucose. (Endogenous lactic acid bacteria (LAB) failed to ferment rice). Folate was also added to the mixture as a factor. The mixtures were extruded into 50 mL plastic syringes, where the needle end of the barrel had been excised by lathe. The lubricated barrel was overfilled to 60 mL, capped with a layer of ParafilmTM and aluminium foil, sealed tightly by rubber band and incubated at 30°C. Over time the piston was progressively advanced to yield samples for microbiological, physical, and chemical analysis. Over 96 hours an increase in the LAB count was observed with a concomitant decrease in pH. After fermentation was complete, the samples contained around 8.77 log cfu LAB g-1 with the pH range from 4.38 to 5.08. The microbiological and pH behaviour of each species varied between preparations. Hardness, adhesiveness, springiness and cohesiveness of the treatments increased with fermentation, except for hoki. The treatments showed different colour characteristics with fermentation. The light reflectance (L* values) of the trevally and kahawai treatments increased, while the a* (redness) and b* (yellowness) values decreased. Hoki exhibited smaller colour changes except for yellowness, which increased markedly. Proteolysis, measured colorimetrically by soluble peptide bonds, was greatest for trevally. Lipid oxidation, measured by the thiobarbituric acid method, was least for hoki, notably the species with the lowest fat content. Biogenic amines, which are a general quality indicator of fermented products, increased during fermentation. The trevally treatment generated the highest concentration of amines, but these values were lower than those reported for fermented fish sausage in Southeast Asia. Notably there were no important difference between folate treatments and those without folate. The results point to commercial opportunities and further research with New Zealand marine species, especially trevally. To improve the product quality and to show geographical exclusivity, further research could be done by using starter culture, and a New Zealand staple carbohydrate source such as kumara and potato, and spices and herbs which are commonly used in New Zealand, such as rosemary, thyme and sage or specific to New Zealand, such as horopito. In addition, sensory studies should also be performed before the products could be tested in the market.

Thesis (Ph. D.)--University of California, Riverside, 2010. / Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed May 18, 2010). Includes bibliographical references. Also issued in print.

The social brain hypothesis predicts that larger group size and greater social complexity select for increased brain size. In ants, social complexity is associated with large colony size, emergent collective action, and division of labor among workers. The great diversity of social organization in ants offers numerous systems to test social brain theory and examine the neurobiology of social behavior. My studies focused on the Australasian weaver ant, Oecophylla smaragdina, a polymorphic species, as a model of advanced social organization. I critically analyzed how biogenic amines modulate social behavior in ants and examined their role in worker subcaste-related territorial aggression. Major workers that naturally engage in territorial defense showed higher levels of brain octopamine in comparison to more docile, smaller minor workers, whose social role is nursing. Through pharmacological manipulations of octopaminergic action in both subcastes, octopamine was found to be both necessary and sufficient for aggression, suggesting subcaste-related task specialization results from neuromodulation. Additionally, I tested social brain theory by contrasting the neurobiological correlates of social organization in a phylogenetically closely related ant species, Formica subsericea, which is more basic in social structure. Specifically, I compared brain neuroanatomy and neurometabolism in respect to the neuroecology and degree of social complexity of O. smaragdina major and minor workers and F. subsericea monomorphic workers. Increased brain production costs were found in both O. smaragdina subcastes, and the collective action of O. smaragdina majors appeared to compensate for these elevated costs through decreased ATP usage, measured from cytochrome oxidase activity, an endogenous marker of neurometabolism. Macroscopic and cellular neuroanatomical analyses of brain development showed that higher-order sensory processing regions in workers of O. smaragdina, but not F. subsericea, had age-related synaptic reorganization and increased volume. Supporting the social brain hypothesis, ecological and social challenges associated with large colony size were found to contribute to increased brain size. I conclude that division of labor and collective action, among other components of social complexity, may drive the evolution of brain structure and function in compensatory ways by generating anatomically and metabolically plastic mosaic brains that adaptively reflect cognitive demands of worker task specialization and colony-level social organization.