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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

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.
75

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)
76

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.
77

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

Williams, Sharon R. 16 October 2003 (has links)
No description available.
78

Seasonal Variation of Mud Floc Sizes in Two Small Freshwater Streams

Delay, Lailee Alena 05 June 2024 (has links)
Flocculation is not only an important part of sediment dynamics within coastal marine waters, but is also a factor of sediment transport within small freshwater streams in Blacksburg, Virginia. The goal of this project was to develop a relationship between floc sizes and stream characteristics (temperature, salinity, chlorophyll-a, organic content, TSS, pH) and to compare how that relationship varies seasonally and spatially across two streams in the same watershed with a similar drainage area but different land uses within these areas. Microscopic images of flocs and water samples were taken within two local streams every two to four weeks throughout the span of one year. The images were analyzed to obtain the floc sizes and the water samples were tested in a lab for various stream properties. The compiled data from the entire year were analyzed to determine if there was a seasonal relationship between floc sizes and the various properties of the water. The process was also repeated at multiple locations along the entire length of both of the streams once in the summer and once in the winter to see if there was a spatial relationship within a single stream. Our study found that significant rainfall events tend to have the greatest effect on floc size in the small headwater streams. However, many of the individual variables alone do not correlate strongly with floc size and a combination of variables may be the best way to analyze the floc size. / Master of Science / Flocculation is the process of single particles coming together to form larger aggregated particles called "flocs". This project focuses on flocculation of sediment within local streams and how the sizes of these flocs may vary throughout the year. The rate of flocculation and the size of these flocs can have a large effect on the movement of sediment within freshwater streams. Images of flocs and water properties such as water temperature, salinity, and pH, were analyzed every two to four weeks throughout the span of a year to determine if there was a relationship between floc size and any of the measured water properties. While a relationship between rainfall and floc size was noticed, it is apparent that multiple variables should be factored into the analysis to get the most accurate results.
79

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.
80

Seasonal Shifts : Leadership Decisions and Their Consequences on Kalmar’s Hospitality Workforce

Aoun, Kevin, Thakur, Nityam January 2024 (has links)
This Master’s Degree Project titled "Seasonal Shifts: Leadership Decisions and Their Consequences on Kalmar’s Hospitality Workforce" investigates the complex phenomenon of seasonality in the hospitality sector and its effects on employee relations and leadership in the context of Kalmar, Sweden. For small economies that significantly rely on tourism, seasonality—which is defined by temporal swings in visitor activity—presents both opportunities and challenges. This study focuses on the perspectives from employees and explores the managers' decisions and how they try to control the cyclical nature of tourism and the effect they have on the workers.  Utilizing an extensive theoretical framework encompassing Transformational, Transactional, Ethical, Servant, Democratic, and Seasonal Employee Leadership styles, the study explores the ways in which various methods impact job satisfaction, employee engagement, and retention. Incorporating the Cultural Dimensions Theory enhances the story and offers a more profound comprehension of the interaction between cultural factors and leadership decisions. With its bustling summer tourism industry and sizable student body, Kalmar provides an ideal setting for investigating how leadership choices affect the seasonal workforce. The study discusses how important leadership is in overcoming seasonality-related problems including worker turnover and local community sustainability. The thesis seeks to add to the body of knowledge on leadership in the hospitality sector by providing a thorough examination and insights into the lives of people who deal with the highs and lows of the tourist seasons. In addition, it aims to educate decision-makers in government and business by pointing them in the direction of approaches that sustain small cities' social and economic structures off-peak.

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