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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Seasonal Precipitation Variability and Gully Erosion in Southeastern USA

Luffman, Ingrid, Nandi, Arpita 01 April 2020 (has links)
This study examines the relationship between gully erosion in channels, sidewalls, and interfluves, and precipitation parameters (duration, total accumulation, average intensity, and maximum intensity) annually and seasonally to determine seasonal drivers for precipitation-related erosion. Ordinary Least Square regression models of erosion using precipitation and antecedent precipitation at weekly lags of up to twelve weeks were developed for three erosion variables for each of three geomorphic areas: channels, interfluves, and sidewalls (nine models in total). Erosion was most pronounced in winter months, followed by spring, indicating the influence of high-intensity precipitation from frontal systems and repeated freeze-thaw cycles in winter; erosion in summer was driven by high-intensity precipitation from convectional storms. Annually, duration was the most important driver for erosion, however, during winter and summer months, precipitation intensity was dominant. Seasonal models retained average and maximum precipitation as drivers for erosion in winter months (dominated by frontal systems), and retained maximum precipitation intensity as a driver for erosion in summer months (dominated by convectional storms). In channels, precipitation duration was the dominant driver for erosion due to runoff-related erosion, while in sidewalls and interfluves intensity parameters were equally important as duration, likely related to rain splash erosion. These results show that the character of precipitation, which varies seasonally, is an important driver for gully erosion and that studies of precipitation-driven erosion should consider partitioning data by season to identify these drivers.
72

Seasonal Distribution and Modeling of Diesel Particulate Matter in the Southeast US

Díaz-Robles, L. A., Fu, J. S., Reed, G. D., DeLucia, A. J. 01 January 2009 (has links)
The fine and ultra fine size of diesel particulate mater (DPM) are of great health concern and significantly contribute to the overall cancer risk. In addition, diesel particles may contribute a warming effect on the planet's climate. The composition of these particles is composed principally of elemental carbon (EC) with adsorbed organic compounds, sulfate, nitrate, ammonia, metals, and other trace elements. The purpose of this study was to depict the seasonality and modeling of particulate matter in the Southeastern US produced by the diesel fueled sources (DFSs). The modeling results came from four one-month cases including March, June, September, and December to represent different seasons in 2003 by linking Models-3/CMAQ and SMOKE. The 1999 National Emissions Inventory Version 3 (NEI99) was used in this analysis for point, area, and non-road sources, whereas the National Mobile Inventory Model (NMIM) was used to create the on-road emissions. Three urban areas, Atlanta, Birmingham, and Nashville were selected to analyze the DPM emissions and concentrations. Even though the model performance was not very strong, it could be considered satisfactory to conduct seasonal distribution analysis for DPM. Important hourly DPM seasonality was observed in each city, of which higher values occurred at the morning traffic rush hours. The EC contributions of primary DPM were similar for all three sites (~ 74%). The results showed that there is no significant daily seasonality of DPM contribution to PM2.5 for any of these three cities in 2003. The annual DPM contribution to total PM2.5 for Atlanta, Nashville, and Birmingham were 3.7%, 2.5%, and 2.2%, respectively.
73

Investigating Seasonal Responses in the Northern House Mosquito, Culex pipiens

Peffers, Caitlin Skye 04 October 2021 (has links)
No description available.
74

Palaeoenvironmental reconstruction: evidence for seasonality at Allia Bay, Kenya, at 3.9 million years

Macho, Gabriele A., Jiang, Y., Leakey, M.G., Williamson, D.K. January 2003 (has links)
No / In an earlier study, stress lines in primate teeth were found to occur on a recurrent basis, probably corresponding to seasonal fluctuations in environmental parameters, such as food availability (Macho et al., J. Hum. Evol. 30 (1996) 57¿70). In the present study this approach was extended to the study of teeth of extant and extinct mammals, with the specific aim to determine the pattern of seasonality at the Australopithecus anamensis-bearing site at Allia Bay, Kenya. It was found that extant and extinct species, who share similar dietary/ecological adaptations, are comparable in their patterns of stress. Typical browsers/mixed feeders were found to exhibit three recurrent disturbances per year, whereas grazers usually only exhibit two. The average spacing between lines is also comparable between extant and extinct species. Hence, while the severity and predictability of the seasons probably fluctuated during crucial periods of hominin evolution, there is little doubt that all hominins lived in a seasonal environment. At Allia Bay, the pattern of stress lines found in mammals suggests that the environmental conditions in which A. anamensis lived may have been comparable to those found in the Masai Mara today.
75

Time-lapse Geophysical Investigations over Known Archaeological Features Using Electrical Resistivity Imaging and Earth Resistance

Fry, Robert J. January 2014 (has links)
Electrical methods of geophysical survey are known to produce results that are hard to predict at different times of the year, and under differing weather conditions. This is a problem which can lead to misinterpretation of archaeological features under investigation. The dynamic relationship between a ‘natural’ soil matrix and an archaeological feature is a complex one, which greatly affects the success of the feature’s detection when using active electrical methods of geophysical survey. This study has monitored the gradual variation of measured resistivity over a selection of study areas. By targeting difficult to find, and often ‘missing’ electrical anomalies of known archaeological features, this study has increased the understanding of both the detection and interpretation capabilities of such geophysical surveys. A 16 month time-lapse study over 4 archaeological features has taken place to investigate the aforementioned detection problem across different soils and environments. In addition to the commonly used Twin-Probe earth resistance survey, electrical resistivity imaging (ERI) and quadrature electro-magnetic induction (EMI) were also utilised to explore the problem. Statistical analyses have provided a novel interpretation, which has yielded new insights into how the detection of archaeological features is influenced by the relationship between the target feature and the surrounding ‘natural’ soils. The study has highlighted both the complexity and previous misconceptions around the predictability of the electrical methods. The analysis has confirmed that each site provides an individual and nuanced situation, the variation clearly relating to the composition of the soils (particularly pore size) and the local weather history. The wide range of reasons behind survey success at each specific study site has been revealed. The outcomes have shown that a simplistic model of seasonality is not universally applicable to the electrical detection of archaeological features. This has led to the development of a method for quantifying survey success, enabling a deeper understanding of the unique way in which each site is affected by the interaction of local environmental and geological conditions.
76

A reappraisal of archaeological geophysical surveys on Irish road corridors 2001-2010. With particular reference to the influence of geological, seasonal and archaeological variables

Bonsall, James P.T. January 2014 (has links)
Geophysical surveys in the Republic of Ireland and elsewhere rarely have the opportunity to receive direct, meaningful and quantitative feedback from ground observed excavations, despite their frequent occurrence as a subsequent phase of development-led archaeological projects. This research critically reappraises the largest and most coherent geophysical archive maintained by a single end-user over a ten year period. The geophysical archive has been collated from 170 reports on linear road schemes as a result of commercially-driven assessments in Ireland, to facilitate the biggest analysis of geophysical survey legacy data and subsequent detailed excavations. The analysis of the legacy data archive has reviewed and tested the influence of key variables that have, in some circumstances, affected the methods and outcomes of geophysical assessments in Ireland over the last 10 years. By understanding the impact of those key variables upon the legacy data - which include archaeological feature type, geology, sampling strategy and seasonality - appropriate and new ways to research linear corridors have been suggested that should be employed in future geophysical survey assessments for a range of environments and archaeological site types. The comprehensive analysis of geophysical surveys from the legacy data archive has created definitive statements regarding the validity of geophysical techniques in Ireland. Key failures that occurred in the past have been identified and a thorough investigation of new and novel techniques or methods of survey will facilitate a more robust approach to geophysical survey strategies in the future. The outcomes of this research are likely to have ramifications beyond the Irish road corridors from which the legacy data derives. / National Roads Authority (NRA)
77

AN EXAMINATION OF THE LINK BETWEEN JANUARY RETURNS AND CONTEMPORANEOUS EARNINGS: IS THE SMALL FIRM/JANUARY EFFECT ON ECONOMICALLY RELEVANT PHENOMENON?

EASTERDAY, KATHRYN E. January 2007 (has links)
No description available.
78

Energy balance, health and fecundity among Bhutia women of Gangtok, Sikkim, India

Williams, Sharon R. 16 October 2003 (has links)
No description available.
79

A Precipitação de neve no Brasil meridional

Schmitz, Claudio Marcus January 2007 (has links)
(RS) e Santa Catarina (SC), Brasil meridional. Para tanto foram usados os dados diários e das normais climatológicas (1961-90) das estações do Instituto Nacional de Meteorologia (INMET). Foi elaborada uma caracterização climática da área de estudo, que forneceu o apoio para a contextualização do fenômeno. Os dados climatológicos básicos (temperaturas médias mensais compensadas, temperaturas mínimas absolutas e totais pluviométricos mensais) foram obtidos diretamente das normais climatológicas publicadas pelo INMET. Os dados referentes aos dias de neve foram compilados diretamente das observações do INMET para planilha eletrônica onde se totalizaram os dias de neve e foram calculadas médias e percentuais convencionais. Em termos sazonais, o período de ocorrência estende-se de maio até setembro, quando a massa de ar polar marítima (mP) tem maior atuação no sul do Brasil. O mês de julho concentra a maioria dos eventos, com mais de 40% dos dias de neve na maioria das estações analisadas. A trajetória do anticiclone móvel polar tem papel fundamental no entendimento do fenômeno, associando-se a maioria dos eventos com passagens interiores (i.e., continentais) do referido sistema atmosférico. As áreas mais altas do Brasil meridional, a partir da cota de 600 m, são as que apresentam as maiores médias anuais de dias com neve, com valores que chegam até a média de 1,8 dias/ano em Cambará do Sul e 2,7 dias/ano em São Joaquim (SC). Esse município possui as mais altas médias de ocorrência da neve. A área de maior recorrência do fenômeno foi chamada de “Planalto da Neve”, subdividida em dois setores: I, acima de 900 m e II, entre 600 m e 900 m. O referido Planalto possui 95.242 km² distribuídos no RS e SC, localizando-se no seu interior 90 cidades gaúchas e 101 catarinenses. A análise da variação inter-anual (com dados de São Joaquim, SC) indicou que, de toda a série estudada, apenas os anos de 1961, 1963, 1971, 1973, 1982 e 1986, não apresentam registro de neve. As nevadas mais relevantes ocorreram nos anos de 1965, 1975, 1988 e 1990. Os intervalos entre períodos de ausência de neve e de nevadas mais importantes indica um ciclo decadal na dinâmica do fenômeno. Apesar dos picos de precipitação em 1988 e 1990, não existe uma tendência de aumento da precipitação de neve naquela cidade. / This work analyzes the seasonal and spatial distribution of snow in Rio Grande do Sul (RS) and Santa Catarina (SC), southern Brazil. This analysis is based on the daily data and the Climatological Normals (1961-1990), coming from the local weather stations, maintained by the Instituto Nacional de Meteorologia (INMET), to obtain the basic climatological data (compensated monthly medium temperatures, minimum absolute temperatures and monthly pluviometric totals). To contextualize the study of this phenomenon, the characterization of the climate was prepared for the region. The total days of snow, averages and conventional percentages were compiled directly from INMET observations. In seasonal terms, the occurrence period extends from May to September, when the marine polar air mass (mP) has greater influence in the south of Brazil. The month of July concentrated most of the events, with more than 40% of the days of snow in most of the analyzed stations. The polar anticyclone has a fundamental role in the understanding this phenomenon, associating most of the events with continental passages of this atmospheric system. The highlands of southern Brazil, starting at 600 m, present the largest annual averages of days with snow, values averaging from 1.8 day/year in Cambará do Sul (RS) to 2.7 day/year in São Joaquim (SC), the highest averages of snow occurrence. The area of occurrence of the phenomenon is called “Planalto da Neve”, and is subdivided in two sectors: 1) above 900 m and, 2) between 600 m and 900 m. This plateau possesses 95.242 km² and is spread out between RS and SC, comprising 90 municipalities of RS and 101 in SC. The analysis of the interannual variation considering the data from São Joaquim, SC ) indicated that, from the studied series, 1961, 1963, 1971, 1973, 1982 and 1986, did not register snow. The most relevant snowfalls happened in the years of 1965, 1975, 1988 and 1990. The intervals between periods with absence of snow and of more important snowfalls indicates a decadal cycle in the dynamics of the phenomenon. Regardless of the peaks in precipitation registered for 1988 and 1990, there is no trend in the increase of snow precipitation for São Joaquim.
80

A Precipitação de neve no Brasil meridional

Schmitz, Claudio Marcus January 2007 (has links)
(RS) e Santa Catarina (SC), Brasil meridional. Para tanto foram usados os dados diários e das normais climatológicas (1961-90) das estações do Instituto Nacional de Meteorologia (INMET). Foi elaborada uma caracterização climática da área de estudo, que forneceu o apoio para a contextualização do fenômeno. Os dados climatológicos básicos (temperaturas médias mensais compensadas, temperaturas mínimas absolutas e totais pluviométricos mensais) foram obtidos diretamente das normais climatológicas publicadas pelo INMET. Os dados referentes aos dias de neve foram compilados diretamente das observações do INMET para planilha eletrônica onde se totalizaram os dias de neve e foram calculadas médias e percentuais convencionais. Em termos sazonais, o período de ocorrência estende-se de maio até setembro, quando a massa de ar polar marítima (mP) tem maior atuação no sul do Brasil. O mês de julho concentra a maioria dos eventos, com mais de 40% dos dias de neve na maioria das estações analisadas. A trajetória do anticiclone móvel polar tem papel fundamental no entendimento do fenômeno, associando-se a maioria dos eventos com passagens interiores (i.e., continentais) do referido sistema atmosférico. As áreas mais altas do Brasil meridional, a partir da cota de 600 m, são as que apresentam as maiores médias anuais de dias com neve, com valores que chegam até a média de 1,8 dias/ano em Cambará do Sul e 2,7 dias/ano em São Joaquim (SC). Esse município possui as mais altas médias de ocorrência da neve. A área de maior recorrência do fenômeno foi chamada de “Planalto da Neve”, subdividida em dois setores: I, acima de 900 m e II, entre 600 m e 900 m. O referido Planalto possui 95.242 km² distribuídos no RS e SC, localizando-se no seu interior 90 cidades gaúchas e 101 catarinenses. A análise da variação inter-anual (com dados de São Joaquim, SC) indicou que, de toda a série estudada, apenas os anos de 1961, 1963, 1971, 1973, 1982 e 1986, não apresentam registro de neve. As nevadas mais relevantes ocorreram nos anos de 1965, 1975, 1988 e 1990. Os intervalos entre períodos de ausência de neve e de nevadas mais importantes indica um ciclo decadal na dinâmica do fenômeno. Apesar dos picos de precipitação em 1988 e 1990, não existe uma tendência de aumento da precipitação de neve naquela cidade. / This work analyzes the seasonal and spatial distribution of snow in Rio Grande do Sul (RS) and Santa Catarina (SC), southern Brazil. This analysis is based on the daily data and the Climatological Normals (1961-1990), coming from the local weather stations, maintained by the Instituto Nacional de Meteorologia (INMET), to obtain the basic climatological data (compensated monthly medium temperatures, minimum absolute temperatures and monthly pluviometric totals). To contextualize the study of this phenomenon, the characterization of the climate was prepared for the region. The total days of snow, averages and conventional percentages were compiled directly from INMET observations. In seasonal terms, the occurrence period extends from May to September, when the marine polar air mass (mP) has greater influence in the south of Brazil. The month of July concentrated most of the events, with more than 40% of the days of snow in most of the analyzed stations. The polar anticyclone has a fundamental role in the understanding this phenomenon, associating most of the events with continental passages of this atmospheric system. The highlands of southern Brazil, starting at 600 m, present the largest annual averages of days with snow, values averaging from 1.8 day/year in Cambará do Sul (RS) to 2.7 day/year in São Joaquim (SC), the highest averages of snow occurrence. The area of occurrence of the phenomenon is called “Planalto da Neve”, and is subdivided in two sectors: 1) above 900 m and, 2) between 600 m and 900 m. This plateau possesses 95.242 km² and is spread out between RS and SC, comprising 90 municipalities of RS and 101 in SC. The analysis of the interannual variation considering the data from São Joaquim, SC ) indicated that, from the studied series, 1961, 1963, 1971, 1973, 1982 and 1986, did not register snow. The most relevant snowfalls happened in the years of 1965, 1975, 1988 and 1990. The intervals between periods with absence of snow and of more important snowfalls indicates a decadal cycle in the dynamics of the phenomenon. Regardless of the peaks in precipitation registered for 1988 and 1990, there is no trend in the increase of snow precipitation for São Joaquim.

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