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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.
341

Microbial Transformation of Arsenic and Organoarsenic Compounds in Anaerobic Environments

Cortinas Lopez, Irail January 2007 (has links)
Arsenic (As) is a common occurring environmental pollutant. The USEPA has a stricter regulation for arsenic in drinking water (10 ug/L). Small drinking water suppliers from regions with high arsenic backgrounds levels, will need to remove arsenic from drinking water in order to meet the new standard. The proposed treatment by the USEPA is the oxidation of arsenite (AsIII) to arsenate (AsV) followed by the adsorption onto metal oxides (e.g. granular ferrihydrite (GFH)). Large amounts of arsenic-bearing solid waste will be generated and disposed in municipal landfills based on EPA's recommendation. The alkaline and anaerobic conditions prevailing in mature landfills combined with the high content of organic matter and the microbial activity prevailing in landfill could play an important role in the biotransformation and mobilization of sorbed arsenic in landfills. The extensive use of organo arsenical compounds such as pesticides in agriculture has become an emerging source of arsenic contamination in the environment. Roxarsone (4-hydroxy-3-nitrophenylarsonic acid) is a compound supplemented in the poultry feed to enhance growth by controlling coccidian parasites. Chickens excrete the roxarsone without changes in its chemical structure. Land application of chicken manure in agricultural fields is a common practice. Approximately 900 metric tons of roxarsone is estimated to be released into environment in the U.S. annually. The environmental impact is significant when considering that these quantities of arsenic are spread onto relative small land areas in the direct vicinity of poultry houses. The aim of this study is to evaluate the role of anaerobic bioconversion on the fate and mobility of inorganic and organic arsenic compounds. The results taken as a whole suggest that arsenic in drinking water residuals is susceptible to enhanced mobilization due to anaerobic microbial activity, and therefore As mobilization should be expected in mature landfills. Roxarsone was readily biotransformed by a methanogenic consortium to its corresponding amino compound, 4-hydroxy-3-aminophenylarsonic acid (HAPA). A fraction of the HAPA went on to be converted to AsIII after long term incubations. Therefore, land application of roxarsone-containing wastes could potentially lead to the formation of more toxic and mobile forms of arsenic which will have negative impact on the environment.
342

Land Tenure Reforms and Social Transformation in Botswana: Implications for Urbanization.

Ijagbemi, Bayo January 2006 (has links)
Land reforms, with the majority bordering on full scale revision of tenure rules have become a recurrent theme in the agenda of most African states since attaining political independence. For southern Africa, and a number of former colonies where the white settler populations acting in concert with the colonial administrations dispossessed the majority of the native populations of their land, the reforms have taken the form of restitution and redistribution of land. Unlike these types of reforms in southern African and because the Bechuanaland Protectorate was not a settler colony, Botswana has framed its land tenure and land use reforms with an eye on the problems associated with common property management. My dissertation evaluates the effects of Botswana's land reforms on social transformations in Kweneng District by carefully investigating their impacts on households' livelihood strategies, kinship ties, and social balance of power on one hand, and the implications of these transformations for urbanization on the other.While acknowledging the good intentions of the government as encapsulated in the objectives of the reform policies, it is my contention that several areas which were never taken into account during the formulation of these policies have been adversely impacted. Unfortunately, the unintended consequences have overshadowed the targeted ends of the reforms. These results are visible in the contemporary family and kinship structure, the chieftaincy institution, livelihood systems in livestock and arable agriculture, administration of justice, and the phenomenon of urbanization.
343

Studies of vibronic interactions in tetrahedral and iscosahedral systems

Qiu, Qingchun January 1998 (has links)
No description available.
344

THE PECULIARITIES OF GRAMMATICAL TRANSLATION TRANSFORMATIONS IN MODERN ENGLISH LITERATURE / GRAMATINĖS VERTIMO TRANSFORMACIJOS ŠIUOLAIKINEJE ANGLŲ LITERATŪROJE

Laurinavičiūtė, Inga 02 September 2010 (has links)
The aim of this research paper is to analyze the peculiarities of grammatical translation transformations in modern English novel “Bridget Jones’s Diary” (1996) written by Helen Fielding and its translated Lithuanian version. To achieve this aim the following objectives have been set: 1. To present the theoretical background about translation as a science. 2. To represent the linguistic theory about the role of grammar in translation practice. 3. To explain the usage of grammatical translation transformations in the target text. 4. To reveal the distribution of pure and mixed grammatical translation transformations in the intended text. The structure of the work. The theoretical part focuses on the issues of translation. initiating. Namely, the development of translation studies, equivalence, methods, procedures and translation transformations have been presented. In the subsequent part, i.e. the practical analysis, the usage of grammatical translation transformations has been briefly analyzed considering the collected instances. / Darbo tikslas išanalizuoti gramatinių vertimo transformacijų įpatybes šiuolaikinėje anglų kalbos noveleje "Bridžitos Džouns dienoraštis" (1996)parašytos Helen Fielding ir šios knygos lietuviškame vertime. Darbo uždaviniai: 1. Pateikti teorinę apžvalgą apie vertimą kaip mokslą. 2. Pristatyti lingvistinę medžiagą apie gramatines vertimo transformacijas, grupuojant jas į sukeitimas, praleidimas, pridėjimas, pakeitimas. 3. Paaiškinti grynų ir mišrių gramatinių transformacijų pasiskirstymą tyriamajameme kūrinyje. Darbo struktūra. Teorinėje dalyje daugiausia dėmesio skiriama vertimui. Aprašyti: vertimo studijų vystimasis, ekvivalentiškumas, vertimo metodai, procesai ir transformacijos. Praktinėje dalyje analizuojamas gramatinių vertimo transformacijų naudojimas remiantis surinktais pavyzdžiais.
345

Any curriculum will do : structure as a catalyst for adult transformation

Cook, Paul Alexander January 2013 (has links)
This thesis employs phenomenological hermeneutic circle analysis, to investigate structure versus agency and adult identity change in lifelong learning. Achieving transformed agency and enhanced identity is argued to be about other ways of doing and other ways of seeing (Mezirow 2000:21). It proceeds by exploring if curricula employed in education can provide structure and/or the catalyst which allows ‘other’ to be revealed, agency to be regained, and to explicate what contribution curricula might make in transforming adult identities. Drawing upon the disciplines of sociology and psychology it provides holistic interpretations of participant accounts in the contemporary competitive world and explores the interstices in the duality of tensions between the utilitarian, and pragmatic adult, who employs education as a developmental pathway of choice. Interviews with six participants tell individual stories to provide holistic data of their erudition and experiences of cognitive and social change. Data are then employed to essentialise similarities, differences, themes, and congruent essences, and to distil factors which exemplify growth in understanding and expectations of the self. Growth in self-assurance and identity change capability is then contrasted with the fragility of adult identity; whereupon, this thesis critically positions fragility causation amongst the instrumental policies and forces of lifelong learning. Mezirow contends that agency is achieved by elaborating existing frames, learning new frames, transforming habits, and transforming points of view. This thesis moves to discuss the connected nature of these developmental factors and ‘glass ceilings’, and how immanent personal potential is (re) revealed to the adult self. Employing an archaeological hermeneutic research tool which suggests reflection is a central and developing feature in adult’s educational development the thesis finally contends that education is important in the personal delivery of agency over structure, and that curricula of any structurally legitimate form make a significant contribution to allowing persons to both flourish and confront a range of ‘other’ life circumstances and dilemmas.
346

Analysis of the Expression Profiles of Two Isoforms of the Antifungal Protein Osmotin from Gossypium hirsutum

Spradling, Kimberly Diane 05 1900 (has links)
The expression of two cotton osmotin genes was evaluated in terms of the mRNA and protein expression patterns in response to chemical inducers such as ethylene, hydrogen peroxide, and sodium chloride. Reverse transcriptase-polymerase chain reactions (RT-PCR) indicated that osmotin mRNAs are expressed constitutively in root tissues of cotton plants, and that they are rapidly induced in leaf and stem tissues upon ethylene treatment. Real time RT-PCR indicated that osmotin transcript levels were induced 2 to 4 h after treatment with ethephon. The osmotin mRNA levels appear to increase 12 h after treatment, decrease, and then increase again. The osmotin protein expression patterns were analyzed in Western blot analyses using an anti-osmotin antibody preparation. A 24-KDa protein band was detected from cotton plants treated with the inducers. The 24-KDa osmotin proteins were induced 4 h after treatment with ethephon, while down-regulated 96 h after treatment. Multiple osmotin isoforms were observed to be induced in cotton plants upon treatment with ethephon by two-dimensional gel electrophoresis. One goal of this dissertation research was to genetically engineer two cotton osmotin genes to routinely overproduce their antifungal proteins in transgenic Arabidopsis and cotton plants as a natural defense against fungal infections, using co-cultivation with Agrobacterium tumefaciens cells harboring pCAMBIA 2301 vector constructs containing the osmotin genes. Many transgenic Arabidopsis and cotton plants were generated. However, genomic blotting analyses indicated the absence of the osmotin transgenes, but the presence of GUS genes from the vector cassette. Alkaline blot analyses of the vector DNAs from transformed Agrobacterium cells confirmed that an anomalous DNA structural rearrangement or aberrant recombination event probably occurred in the Agrobacterium cells, interdicting the integration of osmotin transgenes into the Arabidopsis and cotton plants. This research provides crucial baseline information on expression of cotton osmotin mRNAs and proteins.
347

Pore water chemistry reveals gradients in mineral transformation across a model basaltic hillslope

Pohlmann, Michael, Dontsova, Katerina, Root, Robert, Ruiz, Joaquin, Troch, Peter, Chorover, Jon 06 1900 (has links)
The extent of weathering incongruency during soil formation from rock controls local carbon and nutrient cycling in ecosystems, as well as the evolution of hydrologic flow paths. Prior studies of basalt weathering, including those that have quantified the dynamics of well-mixed, bench-scale laboratory reactors or characterized the structure and integrated response of field systems, indicate a strong influence of system scale on weathering rate and trajectory. For example, integrated catchment response tends to produce lower weathering rates than do well mixed reactors, but the mechanisms underlying these disparities remain unclear. Here we present pore water geochemistry and physical sensor data gathered during two controlled rainfall-runoff events on a large-scale convergent model hillslope mantled with 1 m uniform depth of granular basaltic porous media. The dense sampler and sensor array (1488 samplers and sensors embedded in 330 m(3) of basalt) showed that rainfall-induced dissolution of basaltic glass produced supersaturation of pore waters with respect to multiple secondary solids including allophane, gibbsite, ferrihydrite, birnessite and calcite. The spatial distribution of saturation state was heterogeneous, suggesting an accumulation of solutes leading to precipitation of secondary solids along hydrologic flow paths. Rapid dissolution of primary silicates was widespread throughout the entire hillslope, irrespective of up-gradient flowpath length. However, coherent spatial variations in solution chemistry and saturation indices were observed in depth profiles and between distinct topographic regions of the hillslope. Colloids (110-2000 nm) enriched in iron (Fe), aluminum (Al), and phosphorus (P) were mobile in soil pore waters.
348

The Role of Ciliary Neurotrophic Factor and TRKB Signaling in Neuroblastoma

DeWitt, John 19 September 2013 (has links)
Neuroblastoma is the most common pediatric cancer in infants, arising from the sympathoadrenal lineage of the neural crest. Despite recent advances in other pediatric cancers, long term survival in high risk cases of neuroblastoma remains below 40%. Therefore, to develop successful therapeutics targeting high risk tumors, further research into the mechanisms involved in high risk tumor formation is necessary. Prognosis in neuroblastoma is determined by a number of factors, including certain genetic and biological variables. The genetic variable correlated most with high risk disease is amplification of the MYCN gene, which is present in ~25% of tumors. Additionally, ~70% of these MYCN-amplified tumors express the neurotrophin receptor TrkB, and its ligand, brain-derived neurotrophic factor (BDNF), with concurrent expression of these proteins correlated with high risk disease independent of MYCN-amplification status. To better understand factors influencing MYCN-amplified tumor cell phenotype, and the role of TrkB signaling in high risk neuroblastoma, the experiments in this dissertation examined growth factor effects on MYCN-amplified tumor cells from the TH-MYCN mouse model of neuroblastoma, as well as the creation, and expression of a constitutively active TrkB receptor in a neural crest derived cell line. Overexpression of MYCN targeted to the sympathoadrenal lineage by the tyrosine hydroxylase (TH) promoter is sufficient to cause neuroblastoma in 100% of mice homozygous for the transgene (TH-MYCN mice). Screening growth factors, in vitro treatment of tumor cells from dissociated TH-MYCN tumors with ciliary neurotrophic factor (CNTF) was found to promote differentiation marked by increased neurite outgrowth, and withdrawal of actively dividing cells from the cell cycle. These effects were both concentration dependent, and specific to CNTF, as all other neurotrophic factors tested had no effect on differentiation. Furthermore, TH-MYCN tumor cells were found to highly express the receptor for CNTF, CNTFR both in vitro and in vivo. Testing the ability of CNTF to affect tumor growth in vivo, CNTF treatment attenuated subcutaneous tumor growth of the TH-MYCN tumor-derived cell line NHO1S in wild type 129/SvJ mice. Therefore, CNTF signaling may be a potential therapeutic target in MYCN-amplified neuroblastoma. In addition to being significantly correlated with a poor prognosis in neuroblastoma, the presence of activated TrkB signaling promotes a more aggressive phenotype in established neuroblastoma cell lines. However, whether TrkB signaling is sufficient to transform neural crest derived cells had not been established. To determine the role of TrkB signaling in malignant transformation, the two immunoglobulin-like (Ig) ligand binding domains were removed from a full length rat TrkB receptor. Expression of this receptor, termed IgTrkB, leads to elevated phosphorylated Erk levels in the absence of ligand, indicating the receptor is constitutively active. When expressed in the neural crest derived cell line NCM-1, constitutive TrkB signaling confers a highly transformed phenotype characterized by enhanced proliferation, anchorage-independent cell growth, anoikis resistance, and matrix invasion. Furthermore, IgTrkB NCM-1 cells upregulate transcripts for a number of cancer promoting genes, in addition to the poor prognosis marker MYCN. In vivo, IgTrkB NCM-1 cells form highly aggressive tumors, requiring euthanasia of mice by 15 days following injection, while wild type cells fail to grow. Thus, TrkB signaling is sufficient to transform cells derived from the neural crest.
349

Puissance des corps en mouvement dans le tango

Molinié, Roxana January 2006 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
350

Transformations de phase et évolutions des microstructures dans l'alliage de titane beta Ti-B19 / Phase transformations and microstructure evolutions in metastable beta titanium alloy Ti-B19

Chang, Hui 28 October 2010 (has links)
Les évolutions de microstructures du nouvel alliage chinois Ti B19 ont été étudiées au cours de divers traitements thermiques et des relations entre microstructures et propriétés mécaniques ont été établies. Les cinétiques de transformations isothermes ont été établies par des mesures de résistivité électrique. Les structures et microstructures ont été caractérisées par DRX synchroton, Microscopies Optiques et Electroniques (MEB, MET). Les cinétiques de transformation et les caractéristiques microstructurales. Les cinétiques de transformation isothermes ont été obtenues, analysées (loi JMAK), et cet ensemble de résultats a conduit à l'établissement du diagramme TTT de l'alliage TiB19. Enfin il a été montré que la vitesse de chauffage a une très forte influence sur les transformations mises en jeu, et qu'une pré déformation plastique accélère les cinétiques de transformation (introduction de nouveaux sites de germination). Enfin les cinétiques de transformation ont été caractérisées en refroidissement continu depuis le domaine monophasé bêta. Une première approche de la modélisation des cinétiques de transformation a été menée en utilisant le loi JMAK et le principe d'additivité de Scheil. Enfin les relations entre microstructures et propriétés sont discutés / The phase transformations and microstructure evolutions has been characterized for different thermal treatments, and the relationships between final microstrures and properties have been investigated in the new metastable Ti-B19 alloy. The isothermal phase transformation kinetics and the influence of different heat treatment phaths have been establisheb by using in-situ electrical Resistivity. The structures have been determined by synchrotron X-Ray Diffraction and the microstructures were observed by SEM and TEM. The results show that phase transformation kinetics and microstructure characteristics are strongly dependent on the aging temperature (ranging from 300 to 700°C). The global isothermal phase transformation phase transformation kinetics has been got and anallyzed with JMAK equation, and the TTT diagram of Ti-B19 alloy has been established. We have also shown that the heating rate has remarkable influence on the isothermal phase transformation behaviors and the pre-deformation accelerates the transformation kinetics. The microstructure evolutions during cooling are obviously dependent on the cooling rates. A first attempt has been made to calculate the transformation kinetics during cooling using JMAK law and Scheil principle. Finally, the relationship between mechanical properties and microstructure has been discussed

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