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Molecular and Genetic Evidence for Antigen Selection in the Pathogenesis of Chronic Lymphocytic LeukemiaSutton, Lesley Ann January 2012 (has links)
Antigens play a critical role in the development of chronic lymphocytic leukemia (CLL) by binding to and stimulating leukemic precursor cells at some point during CLL ontogeny. Nevertheless, much remains unknown and further studies are necessary before an accurate model of antigen-drive can be ascertained. In this context, intraclonal diversification (ID) analysis of immunoglobulin (IG) genes could shed light on whether antigen involvement is restricted to the malignant transformation phase or if the triggering antigen(s) continuously stimulates the CLL clone. Hence, in Paper I we conducted a large-scale analysis of 71 CLL cases and revealed that 28/71 cases carried intraclonally diversified IGHV-IGHD-IGHJ genes. Although most cases showed no or low levels of ID, intense ID was evident within all subset #4 (IGHV4-34/IGKV2-30) cases. Subsequent analysis, in Paper II, of the clonotypic light chains revealed that the outstanding exception again related to subset #4. In such cases, the expressed IGKV2-30 gene was affected by targeted ID, analogous to their partner IGHV4-34 gene. Whilst these results convincingly argued for the role of antigen(s) in the development and evolution of CLL subset #4, this analysis was limited to depicting what was occurring at a single time-point and could not provide insight into the temporal dynamics of the CLL clones. Thus, in Paper III we conducted a longitudinal study of 8 subset #4 cases which enabled us to establish a hierarchical pattern of subclonal evolution. The observed ‘stepwise’ accumulation of mutations strongly supports a role for antigen selection in the pathogenesis of CLL subset #4. In Paper IV we reported a subset of IgG-switched CLL patients with coexisting trisomies of 12 and 19, and propose that the emergence of trisomy 18 in such cases represents a clonal evolution event suggestive of selection due to a clonal advantage. Paper V focused on the IGHV3-21 gene, an adverse prognostic factor in CLL. Since ~60% of IGHV3-21-expressing cases carry stereotyped B cell receptors, recognition of a common antigenic epitope, perhaps of pathogenic significance, is envisaged. Therefore, we investigated IGHV3-21 gene frequency within a Swedish population-based cohort and assessed the impact of stereotypy on clinical outcome. Taken collectively, this thesis provides molecular and genetic evidence for the role of antigen in CLL pathogenesis by convincingly demonstrating that clonal evolution, at least for certain subsets of CLL, is functionally driven rather than a consequence of clonal expansion promoted by nonspecific stimuli.
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Extreme-day return as a measure of stock market volatility : comparative study developed vs. emerging capital markets of the worldKabir, Muashab, Ahmed, Naeem January 2010 (has links)
This paper uses a new measure of volatility based on extreme day return occurrences and examines the relative prevailing volatility among worldwide stock markets during 1997-2009. Using several global stock market indexes of countries categorized as an emerging and developed capital markets are utilized. Additionally this study investigates well known anomalies namely Monday effect and January effect. Further using correlation analysis of co movement and extent of integration highlights the opportunities for international diversification among those markets. Evidences during this time period suggest volatility is not the only phenomena of emerging capital markets. Emerging markets offer opportunities of higher returns during volatility. Cross correlation analysis depicts markets have become more integrated during this time frame; still opportunities for higher returns prevail through global portfolio diversification.
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The closed-end investment company premium puzzle : model development and empirical tests on Swedish and British data /Hjelström, Tomas, January 2007 (has links)
Diss. Stockholm : Handelshögskolan, 2007.
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The influence of institutional environments on the relationship between diversification and firm performance /Tan, Brian R. January 2007 (has links)
Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 131-147).
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Product diversification in U.S. manufacturingMacDonald, James M. January 1983 (has links)
Thesis (Ph. D.)--State University of New York at Buffalo, 1983. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (p. 281-290).
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Internationalization and firm performance the role of intangible resources /Krist, Mario. Bausch, Andreas. January 1900 (has links)
Thesis (Ph. D.)--Jacobs University Bremen, 2008.
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The effects of governance systems on strategy and performance among large Japanese firms a comparison of keiretsu versus independent firms /Kim, Hicheon. January 1995 (has links)
Thesis (Ph. D.)--Texas A & M University, 1995. / Vita. Includes bibliographical references (leaves 117-129).
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Soil erosion prediction under changing land use on MauritiusLe Roux, Jacobus Johannes. January 2005 (has links)
Thesis (M.Sc.)(Geography)--University of Pretoria, 2005. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.
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The role of social and ecological processes on phenotypic evolution in birdsSheard, Catherine January 2016 (has links)
The broad concept of 'biodiversity' can be roughly separated into two related components: trait diversity and species richness. Despite the fact that one or both of these types of biodiversity underlie much of ecology, evolution, and conservation, however, it remains largely unknown how traits and speciation dynamics can interact, particularly at a large scale. My thesis uses modern phylogenetic comparative methods and a new global database of avian morphological traits to quantify and predict the drivers of biodiversity across the world's birds, focusing particularly on the relative roles of ecological and social traits to understanding broad evolutionary patterns. In Chapter 2 I present a survey of avian functional traits, focusing on eight measurements of the beaks, wings, tails, and tarsi of 42,334 individuals representing 10,023 extant and recently extinct species. The global trait distribution of avian communities is consistent with a competition-based model of community assembly, and I find no evidence of environmental filtering at the biome level. The traits exhibited within avian orders tend to become more dissimilar as species richness increases, with the notable exception of the Passeriformes, an order containing around 60% of the total avian species richness but occupying a region of morphospace expected of a clade two orders of magnitude smaller. The Passeriformes also possess remarkable vocal morphology and behavior, and thus I spend the next three chapters of this thesis focused on the role of social processes in avian evolution. In Chapter 3, I use detailed morphological and vocal trait data from the suboscine family Furnariidae to demonstrate that social traits evolve faster and with less regularity than ecological traits. I then in Chapter 4 examine the social and ecological drivers of female song in birds, a widespread trait whose persistence challenges traditional sexual selection theory. I find that the separate drivers of male and female song can be explained by social selection theory, a framework which encompasses all social interactions above and beyond competition for mating opportunities. In Chapter 5 I apply this concept of social selection to macroevolutionary studies, using sex-specific song behaviors to separately investigate the roles of social and sexual selection on speciation and extinction rates. I demonstrate that lineages with male-only song (sexual selection) diversify faster than lineages with both male and female song (social selection). This result suggests that social selection theory may inform the controversial relationship between sexual selection and diversification. Finally, in Chapter 6 I look at the role of dispersal in modulating these speciation and extinction rates. Using data from the wing morphologies of 26,043 individuals from 6,028 species, I test the 'intermediate dispersal hypothesis', hitherto only examined at small scales, across the order Passeriformes, revealing that the highest rates of diversification are indeed found in lineages with an intermediate capacity for flight. When birds that defend year-round territories are considered separately from non-territorial birds, however, the intermediate dispersal hypothesis only holds for territorial birds, demonstrating the importance of considering the ecological context of traits in macroevolutionary studies. Together, my results present evidence that both social and ecological processes facilitate the generation and maintenance of biodiversity in birds.
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The sunflower value chain : a case study in Babati, TanzaniaLarsson, Susanna January 2018 (has links)
The aim of this bachelor thesis was to investigate how local farmers of sunflower and local processors of sunflower oil in Babati, Tanzania perceive constraints and possibilities to value chain upgrading by conducting a case study. Open-ended interviews were conducted during a period of eight weeks with local sunflower farmers, local sunflower processors and other actors with knowledge of the sunflower value chain. The results from the study show that the main constraints perceived by farmers were lack of capital and incentive to buy new seeds, lack of knowledge of how to re-plant old seeds, their lack of bargaining position and market knowledge which together put restrains on their market access. The main constraints, perceived by local processors, were lack of access to credit, lack of market access with regard to sunflower cakes, a bi-product of sunflower oil production, and a shortage of sunflower seeds on the local market. With regard to the shortage of seeds produced in the area this was discussed further with the respondents as it seems to be connected with actors need for diversification as a form of risk aversion. The main upgrading options as perceived by farmers were value addition by also processing and selling the sunflower oil and different forms of horizontal integration. The main upgrading option perceived by local processors of sunflower oil was an insourcing of the labelling and packaging of sunflower oil which would create access to higher value markets.
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