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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

A SYSTEMATIC APPROACH TO ANALYZING PRE-CLOSURE OPERATIONAL PERFORMANCE OF THE PROPOSED REPOSITORY FOR HIGH-LEVEL NUCLEAR WASTE AT YUCCA MOUNTAIN, NV

Spradley, Leah L 05 May 2008 (has links)
This research aimed to measure the operational impact of various strategies for utility loading behavior for commercial spent nuclear fuel (CSNF), as well as thermal design parameters involving waste transportation and emplacement of CSNF during the pre-closure period at Yucca Mountain, NV (YM). Specific objectives included: (1) generation of probable scenarios for waste stream quantities and thermal properties, (2) identification of performance trade-offs in surface facility design parameters and operating decisions, and (3) evaluation of safety and throughput implications of pre-closure strategies. These objectives were accomplished by modeling the pre-closure phase of YM operations as an integrated waste management system. Through application of this model, a better understanding was gained of how various waste management strategies influence facility design assumptions. Advantages and disadvantages of various operating strategies were identified in terms of safety considerations and throughput of surface facilities. This led to an opportunity for making recommendations that have potential to result in improved performance. Strategies that required fewer canisters to be aged and those that contained fewer dual-purpose canisters (DPCs) resulted in lower frequencies of dropped canisters and spent nuclear fuel assemblies. Results indicate that DOE estimates are within the likely range of frequencies for a drop event that is generated by this analysis. The consequences of these events are low enough that their frequency will not likely impact the ability to meet regulatory requirements. Still, DOE could strengthen its preliminary hazards analyses by adopting a probabilistic approach to estimating the drop frequency in evaluating pre-closure safety. This would help to communicate the risk posed by the drop events, and allow for an analysis that is less reliant on deterministic estimates of waste stream quantities and crane drop rates. Pending future agreements between waste generators and the Department of Energy, the capacity of the Wet Handling Facility may need to be increased in order to efficiently handle assemblies arriving in DPCs and bare-fuel transportation casks. Furthermore, because design goals for throughput have been defined in terms of surface buildings as opposed to functional needs, there is a redundancy in functional capability of the Canister Receipt and Closure Facility and the Receipt Facility which should be taken into account in order to design a more efficient system. An alternative design for throughput requirements, based on functional demands of the system, is proposed.
72

THE EFFECTS OF FIRM AND FACILITY CHARACTERISTICS ON ENVIRONMENTAL COMPLIANCE

Recher, Marcella Andrea 08 July 2009 (has links)
This study examines the relationship between firm and facility characteristics and environmental compliance rates. A framework to help analyze this relationship is provided by deterrence theory which suggests that given the same level of government monitoring and enforcement, facilities with higher compliance costs will have lower compliance rates. The literature implies that firms and facilities with certain characteristics face higher costs to ensure compliance with regulations. For example, it has been proposed that plants that are part of large firms, multi-facility firms, or publicly traded firms will incur higher agency costs monitoring employees to make sure they are complying with regulations. Similarly, it is thought that large facilities and facilities located in a different state than the firms headquarters will also face higher agency costs. In addition, it is suggested that foreign-owned plants will confront higher costs developing the expertise to comply with domestic regulations. Understanding the nature of these costs and how they relate to firm and facility characteristics could assist policymakers with developing more targeted environmental compliance strategies. The current study uses data collected on a sample of chemical facilities to analyze whether these characteristics affect facility violation rates, as measured by compliance with air permits. The results suggest that plants with more employees and plants that are part of multi-facility firms are more likely to be out of compliance. Plants that are part of firms with out-of- state headquarters were unexpectedly found to have lower violation rates. None of the other firm and facility characteristics were found to be significant predictors of facility violation rates.
73

Carbon Information Disclosure Strategies (CIDS): A Decision Methodology Framework For Optimizing Carbon Disclosure

Meghreblian, Shari L 27 July 2010 (has links)
This dissertation is concerned with the development of a decision making framework which companies and organizations can use in establishing an effective carbon disclosure strategy. This is accomplished by first researching the current practice of carbon disclosure both in theory and in practice. Next, a benchmarking study was conducted analyzing the carbon disclosure efforts of a sample of 83 U.S.-based companies across nine industrial sectors. Finally, a decision making methodology framework for determining carbon information disclosure strategy is presented that was developed as part of this research and validated by peer-review process.
74

Is Green Good? - A Study of Environmental Management Strategy and its Impact on Competitiveness

Alic, Muamer, Tiukhtiaeva, Anna January 2012 (has links)
The purpose of this thesis is to analyze environmental management in companies and how it affects competitiveness. In order to do this a case study of two Swedish and two Russian companies was done by conducting interviews. The theoretical framework consists of environmental management strategy and competitiveness literature which are relevant to the study and research questions. The empirical findings include the case firm’s view of environmental management and competitiveness in their company. The conclusions of this thesis are that environmental management strategy can have a positive impact on competitiveness, but it depends on the management attitude in the company.   Key words: Environmental management; strategy; competitiveness.
75

Clinical and Diagnostic Evidence of Two Distinct Sialodacryoadenitis Virus Outbreaks

Grant, Marie Christina 12 July 2002 (has links)
Two viral outbreaks occurred 3 years apart (1997 and 2000) in the vivarium at the Pennington Biomedical Research Center. The etiology of both outbreaks was determined by enzyme-linked immunosorbent assay (ELISA) to be sialodacryoadenitis virus. The focus of this work was to fulfill Kochs postulates and definitively confirm the outbreak etiologies using 4 distinct diagnostic laboratory techniques: cell culture, indirect immunofluorescent assay (IFA), transmission electron microscopy (TEM), and reverse transcriptase polymerase chain reaction (RT-PCR). During each outbreak, infected rats were euthanatized, serum was collected by exsanguination, and infected tissues (submandibular salivary glands, Harderian glands, and lung tissue) were harvested and flash frozen in liquid nitrogen for later extraction and analysis of viral particles (field strains). The field strains were compared to the catalogued type-strain virus from the American Type Culture Collection sialodacryadenitis virus Strain 681 (the ATCC strain). Contrary to ATCC strain viral replication in culture on L2p176 (coronavirus permissive) cells, it was determined that the field strain viruses did not grow well in cell culture, but could be propagated in experimentally infected rats. IFA revealed reactivity between the infected rat serum from each outbreak and the ATCC strain, indicating marked antigenic similarity. The viral morphology, ultrastructural cellular pathology, and location of the stages of replication in field strain infected L2p176 cells examined by TEM were consistent with coronavirus infection. Genetic confirmation of the identity of the field strains was accomplished by RT-PCR. ATCC strain sequence analysis revealed a 412 base pair portion of the spike protein gene (total length: approximately 2000 base pairs) that could be amplified for sequence analysis and comparison. The amplification product, produced from each isolate, was purified, further amplified by bacterial plasmid insertion, and compared to each of the other products and to the published PubMed sequence database. Comparison of the fragments revealed homology with published data on the spike protein gene of sialodacryoadenitis virus. This study lays the groundwork for future analysis of the entire spike protein of the field strains, in comparison with the ATCC strain, to determine genetic bases for variations in infectivity and virulence of sialodacryoadenitis virus isolates.
76

Bacillus anthracis Spore Concentrations at Various Carcass Sites

Coker, Pamala Rose 08 November 2002 (has links)
Bacillus anthracis, the etiological agent of the disease anthrax, is a bacteria of great importance, both in the past and today. Despite this importance, many questions remain regarding defending against its use as a biological weapon, the bacteria's variation in virulence, and its epidemiology in nature. Using Etest strips (AB BIODISK, Solna, Sweden) to measure the MICs, 25 genetically diverse isolates of B. anthracis were tested to determine their susceptibility to seven clinically relevant antimicrobial agents. Using the NCCLS MIC breakpoints for staphylococci, three isolates were found to be resistant to penicillin and negative for beta-lactamase production. From a group of investigations, results indicated B. anthracis virulence is related to clonality and the copy numbers per cell of the virulence plasmids, pXO1 and pXO2. Isolates were characterized with respect to their plasmid copy number (pXO1/2) using a novel method of quantitative PCR and the numbers differ greatly from previous reports. Anthrax Vaccine with Adjuvant (AVA) vaccinated guinea pigs were challenged with 20 B. anthracis strains representative of worldwide genetic diversity. A virulence model was constructed by combining the survival, plasmid copy number, and genotyping (based on multilocus variable number tandem repeat analysis typing) data of each isolate. The model obtained was validated using a randomly chosen set of 12 B. anthracis isolates and verified model robustness. Carcass disposal methods, incineration and burial, are recommended to decrease or prevent environmental spore contamination. The extent of contamination from an anthrax carcass is almost totally unknown despite the method of disposal. Studies of environmental contamination by spores of B. anthracis from infected carcasses have only recently been possible because of new technologies. A method utilizing real-time quantitative PCR was developed to quantitate B. anthracis in environmental samples. Absolute quantitation was made possible by the use of clones. This method has allowed the evaluation of the environmental contamination by the different carcass disposal methods and by scavenging of the carcass. The results support the complete burning of a carcass soon after death as the method choice to decrease environmental contamination for the disposal of anthrax affected carcasses.
77

The Epidemiology of Shiga-Toxigenic Escherichia coli O157:H7 in Louisiana Dairy Cattle, Beef Cattle, and White-Tailed Deer

Dunn, John Robert 11 April 2003 (has links)
Shiga-toxigenic Escherichia coli (STEC) O157:H7 is an important human pathogen. Dairy cattle, beef cattle, and white-tailed deer (WTD) are involved in STEC O157:H7 transmission to humans. We conducted cross-sectional studies in Louisiana, using sensitive microbiological methods, in dairy cattle, beef cattle, and WTD to investigate the epidemiology of STEC O157:H7. Results of the dairy studies are as follows. In the point prevalence study, summer-time prevalence in herds was 38.5%, with a cow-level prevalence of 6.5%. Among positive herds, cow-level prevalence ranged from 3%-34.6%. Three of five herds sampled in the longitudinal study were positive. Cow-level prevalence increased during spring and summer. Adult dairy cattle during the warm season had increased odds of STEC O157:H7 fecal shedding. Lactating dairy cows had increased odds of STEC O157:H7 fecal shedding compared to dry cows. In the mouth, hide, and fecal study, cow-level prevalence estimates of STEC O157:H7 in the mouth, on the dorsal hide, and from feces were 0%, 0.7%, and 25.2%, respectively. We sampled weaned beef cattle at the beginning and end of a preconditioning program. Five of twenty-nine herds were shedding STEC O157:H7 or Escherichia coli (EC) O157:H7 initially. No cattle were shedding STEC O157:H7 or EC O157:H7 at the end. We found 0.7% of weaned beef cattle shedding STEC O157:H7. The animal-level prevalence of the O157:H7 serotype, including shiga toxin (stx)-deficient isolates, was 2.5%. We expected, but did not observe, increased shedding or the spread of STEC O157:H7 subtypes. Two WTD field studies were conducted. We collected 338 fecals from hunter-harvested WTD and found one positive sample. The isolate was stx-deficient and sorbitol positive. In the second field study, we isolated STEC O157:H7 in a captive WTD herd, but were unable to demonstrate seasonal trends in fecal shedding. Louisiana reports relatively few human STEC O157:H7 cases. We detected STEC O157:H7 in each of our studies. We demonstrated high fecal prevalence, seasonal shedding, and hide contamination in dairy cattle. Epidemiologic studies in ruminant populations should be revisited using sensitive methods. Studies investigating the human incidence of STEC O157:H7 in relation to presumed ruminant reservoirs are warranted.
78

Role of Chondrocyte Apoptosis in the Pathogenesis of Equine Osteoarthritis

Kim, Dae Young 08 April 2002 (has links)
Osteoarthritis (OA), a non-inflammatory, degenerative disease of articular cartilages, is a common cause of poor performance and early retirement in equine athletes. Pathologically, OA is characterized by matrix degradation and decreased chondrocyte numbers. A mechanical stress is believed to be the major etiologic factor of OA development. Recent studies have indicated that apoptosis is responsible for hypocellularity in OA cartilage and that chondrocyte death by apoptosis could directly contribute to matrix degradation. Increased nitric oxide (NO), a free radical, has been implicated as a cause of chondrocyte apoptosis. No studies, however, have been performed on chondrocyte apoptosis in equine OA. We investigated chondrocyte apoptosis in equine OA cartilage and its relationship to matrix degradation and NO production. Furthermore, we studied whether mechanical stress could induce chondrocyte apoptosis and how NO production and Bcl-2 and caspase-3 proteins contribute to chondrocyte apoptosis by using a novel pressure-loading system. Five OA and three normal equine articular cartilage samples were graded histopathologically and stained with polyclonal nitrotyrosine antibody. Chondrocyte apoptosis was determined by TUNEL assay. For pressure-loading experiment, equine chondrocytes were isolated separately from superficial and deep layers of articular cartilages, embedded in alginate constructs, and intermittently pressurized at 1,000 ± 100 psi (approximately 6.8 ± 0.6 MPa) for 12 hours. TUNEL assay, immunohistochemistry with polyclonal antisera to Bcl-2 and caspase-3, and colorimetric nitrite assay were applied to the chondrocytes that adhered on glass slides by cytospin. Chondrocyte apoptosis occurred much more frequently in equine OA cartilage than in normal cartilage, and was closely correlated with matrix degradation and NO production. The cyclic hydrostatic pressure-treated chondrocytes had a higher percentage of apoptosis than the controls. The pressure-loaded chondrocytes also produced increased NO and expressed elevated Bcl-2 and caspase-3, as compared with the control groups. The present study suggests that pressure-induced NO levels play a critical role in the equine chondrocyte apoptosis process through Bcl-2 and caspase-3 pathways and mechanical stress may contribute to equine OA pathogenesis via chondrocyte apoptosis induced by endogenous NO.
79

Quantitative Trait Loci Mapping for Agronomic and Fiber Quality Traits in Upland Cotton (Gossypium hirsutum L.) Using Molecular Markers

Akash, Muhanad Walid 07 August 2003 (has links)
The breeding of Upland cotton (Gossypium hirsutum L.) cultivars that combine high yield and fiber quality is a major challenge to the breeder. The understanding of the quantitative trait loci (QTL) contributing to agronomic and fiber quality traits offers an excellent route to solve this problem. A QTL analysis was carried out after an F<sub>2:3</sub> population composed of 138 lines, derived from the intraspecific cross between Paymaster 54 and PeeDee 2165, was developed and a linkage map including 143 AFLP markers was constructed. The F<sub>2:3</sub> population was grown in two locations, Alexandria and Baton Rouge in LA. The 143 linked markers were assigned to 13 major and 15 minor linkage groups, the 28 linkage groups cover a genetic distance of 1773.2 cM. This gives coverage of 37.7% of the cotton genome (4700 cM). Single-marker analysis, including simple and logistic regression, and interval marker analysis, including interval mapping (IM) and composite interval mapping (CIM), was used. Interval mapping was used to study QTL interaction effects with the environment. For the agronomic traits, the same five QTL were detected, using a significant threshold of 2 LOD, in both IM and CIM. These include two for lint weight per boll, two for seedcotton weight per plant, and one for lint percentage, which collectively, based on IM analysis, explained 32.5%, 28.6%, and 4.4% of the phenotypic variation, respectively. In total, seven and nine different QTL were detected by IM and CIM, respectively. For the fiber quality traits, the same nine QTL were detected in both IM and CIM. These include one for fiber elongation, one for length, two for uniformity, three for strength, and two for micronaire, which collectively, based on IM analysis, explained 50.9%, 18.7%, 69%, 49.6%, and 25.3% of the phenotypic variation, respectively. In total, nine and 19 different QTL were detected in IM and CIM, respectively. Eleven QTL were found to have significant interaction effects with the two locations. Future efforts in QTL mapping should focus on developing more saturated maps, using larger population sizes, and more powerful statistical algorithms and theories for identifying QTL and elucidating QTL X environment interactions.
80

Genetic Mapping of Agronomic Traits from the Interspecific Cross of Oryza sativa (L.) and Oryza glaberrima (Steud.)

Aluko, Gabriel Kayode 13 November 2003 (has links)
Wild relatives of cultivated rice varieties offer new genetic sources for enhancing economic value, but traditional interval mapping techniques have not gained widespread support among applied researchers for marker assisted selection. The objectives of this study were to detect quantitative trait loci (QTL) for agronomic traits in a hybrid mapping population and compare the non-parametric Discriminant Analysis (DA) procedure with traditional approaches for accuracy and precision. In addition, the effects of population structure on marker-assisted classification were explored. A molecular linkage map comprising 100 SSR markers that spanned the rice genome at intervals of 10.5 cM on the average was constructed based on 312 doubled haploid lines derived from the cross interspecific Oryza sativa x O. glaberrima. The mapping population was evaluated in replicated field plots in Colombia and Louisiana in 2001 and 2002, respectively. QTLs were identified for grain, milling and eating qualities and important agronomic traits such as heading date, plant height, number of tillers per plant, panicle length, grain yield and 1000-grain weight. A total of 28 QTLs were detected for 10 grain quality traits, and 22 QTLs for six agronomic traits were detected that were significant in at least one environment, but only seven were significant in both environments. SSR markers that best discriminated between pre-defined groups of high and low trait values were selected by stepwise DA. Using a k-nearest neighbor algorithm, the largest phenotypic differentiation (3 standard deviations) between two contrasting phenotypic groups resulted in 100% correct classification. Adjustments for population structure resulted in a 5-fold decrease in number of markers needed to achieve the same level of accuracy. These results demonstrated that procedures such as DA and consideration of population structure can be used for efficient marker-based allocation of the doubled haploid lines into pre-defined groups for yield and other agronomic traits. Finally, DA-selected markers pointed to the same or closely linked regions on the linkage map that in turn underscored the validity of the DA approach for genetic mapping.

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