Cooperative oxygen binding by vertebrate tetrameric hemoglobins (Hbs) has been extensively studied and is relatively well understood. Nonetheless, Hill coefficients greater than four have been reported for adult avian, amphibian, and reptilian red blood cells. Such reports also exist for embryonic red cells from various animals. These results are controversial and not yet convincingly established. Oxygen binding studies on avian Hb D, which is known to undergo deoxygenation-dependent self-association, were carried out to answer this question. The goal was to determine unequivocally whether Hill coefficients greater than four occur. Such high Hill coefficients were observed but only at very high Hb D concentrations. Moreover, the early model of avian deoxy Hb D self-association was found to be incomplete. The model has now been expanded to describe better the observed sedimentation data at high Hb concentrations. The possibility that embryonic deoxy Hbs self-associate was also assessed by sedimentation studies of deoxygenated Hb solutions from a marsupial, the tammar wallaby. The results obtained show unambiguously that these embryonic Hbs self-associate upon deoxygenation. Recent phylogenetic analyses suggest that the avian [alpha superscript D]-globin originated from embryonic [alpha]-globins. This finding suggests that the propensity to self-associate upon deoxygenation is an intrinsic property of tetrameric Hbs with embryonic [alpha]-globins. Furthermore the residues mediating the inter-tetramer interactions in adult avian deoxy Hb D and embryonic deoxy Hbs are likely to be the same. Recombinant globins were expressed in bacteria and protocols for the assembly of avian recombinant tetrameric Hb D developed. Initial measurements by sedimentation were carried out to verify the role of a conserved glutamate residue previously speculated to be involved in inter-tetramer interactions. The present studies provide a framework for future investigations of deoxygenation-dependent Hb self-association. In particular the need to carry out oxygen equilibrium measurements at high Hb concentrations as well as sedimentation studies of the deoxygenated Hb solutions is stressed. / text

Thesis (M.S.)--University of Michigan, 1996. / Includes bibliographical references.

Thesis (M.S.)--University of Michigan, 1996. / Includes bibliographical references.

Thesis (M.S.)--University of Michigan, 1991.

Thesis (M.S.)--University of Michigan, 1991.

No description available.

The draft for a Common Consolidated Corporate Tax Base Directive in the European Union includes the suggestion for an apportionment formula which allocates taxable group profits to group member corporations. These allocated profits shall then be taxed in the respective Member States. The draft directive delegates the right to define one factor of the apportionment formula, the term "Employee" to the Member States, who are therefore free to choose a narrow or a broad definition, the latter including also atypical employment schemes. Using a game-theoretic approach the paper shows that the individually rational strategy of any Member State to define "Employee" broadly so as to maximize the volume of the apportionment factor and thus maximize the allocated share of taxable income is only the best solution when tax rate differences and differences in the volume of atypical employment schemes are disregarded. If such differentials and the corporate groups' reactions to different Member States' definitions are included in modelling the game's pay-offs a narrow definition of "Employee" yields the highest individual pay-offs to the Member States involved. This change of dominant strategies is triggered by the corporate group's shifting of the employment factor from high-tax to low-tax Member States. Our paper differs from previous research on the economic effects of the CCCTB apportionment formula as it is the first paper identifying and analysing the employment factor and its distorting effects. The paper discusses possible tax minimizing strategies for corporate groups by shifting workforce and develops a model to quantify these potential relocations. Furthermore the paper presents advice to policy makers in their "Employee" definition decision and shows how Member States could use this definition to both minimize outward factor shifting and maximize inward factor shifting.(authors' abstract) / Series: WU International Taxation Research Paper Series

Cette recherche porte sur une catégorie spécifique de travailleurs, les Travailleurs Indépendants Economiquement Dépendants (TIED), qui associent une indépendance juridique à une dépendance économique vis-à-vis d’un seul client. En cumulant des caractéristiques typiques des deux catégories classiques que sont les salariés et les travailleurs indépendants, les TIED s’inscrivent dans une zone grise du marché du travail. A partir d’une étude qualitative menée auprès de TIED français et brésiliens du secteur des Technologies de l’Information, nous nous interrogeons sur la signification sociale de cette forme d’emploi hybride et sur la façon dont elle émerge sur des marchés du travail aussi différents que ceux de la France et du Brésil. L’analyse des conditions de travail des enquêtés permet d’abord de situer les TIED sur un continuum entre salariat déguisé et véritable travail indépendant et de distinguer deux profils-types : les prestataires intégrés à la structure commanditaire et les indépendants en transition. Pour étudier les trajectoires professionnelles de ces travailleurs, nous mobilisons ensuite l’approche par les capabilités d’Amartya Sen (2000) : nous montrons que les parcours des TIED – privés des protections du droit du travail par leur indépendance juridique – reposent sur des processus d'accumulation et de conversion de différents types de ressources en libertés réelles (ou capabilités). De plus, si l’approche de Sen permet d’expliquer les différences de capabilités observées au sein de notre échantillon, nous proposons d’enrichir son cadre d’analyse afin de l’adapter à l’étude de trajectoires socioprofessionnelles. Les analyses réalisées nous conduisent enfin à distinguer deux groupes d’enquêtés, les "TIED réticents" et les "TIED épanouis" : les TIED réticents, plus nombreux au Brésil, expriment un attachement fort au salariat, alors que les TIED épanouis voient dans la position de TIED une façon d’échapper à des emplois décevants et trouvent souvent avantage à une situation qui leur offre plus d’autonomie que le salariat et plus de confort que la véritable indépendance. En nous appuyant sur les travaux de Fraser (2010) et Boltanski et Chiapello (2011), nous montrons comment le positionnement des TIED épanouis contribue indirectement à la remise en cause du rôle de l’Etat social.Les TIED apparaissent en définitive comme une figure emblématique d’un processus ambivalent d’individualisation qui contribue à l’émergence d’un sujet en quête d’autonomie, délié de ses appartenances traditionnelles, tout en favorisant une confrontation directe de l’individu avec le marché qui accroît les inégalités. Dès lors, si les désirs d’émancipation et d’autonomie des TIED épanouis nous semblent devoir être pris au sérieux, une réflexion s’impose sur les mesures susceptibles d’étendre les capabilités des individus tout en luttant contre l’exacerbation des inégalités et en préservant un système de mutualisation des risques fondé sur la solidarité. / This research deals with a specific category of workers, the Economically Dependent Self-employed Workers (EDSW), who associate legal independence with an economic dependence upon a single client. Combining typical characteristics of two traditional labor categories, wage-labor and self-employment, EDSW fall within a grey zone of the labor market. Starting from a qualitative survey conducted among French and Brazilian EDSW from the Information Technology sector, we question the social significance of this hybrid employment form and the way it emerges in labor markets as dissimilar as those of France and Brazil. At first, the analysis of EDSW working conditions enables to place them on a continuum between disguised wage-labor and real self-employment and to identify two typical profiles: service providers integrated to the client structure and transitioning self-employed workers. To study their occupational path, we then mobilize Amartya Sen’s capability approach (2000): we show that the careers of EDSW – deprived of labor law protection by their self-employment status – rely on accumulation and conversion processes of various resources types into real freedom (or capabilities). Moreover, if Sen's approach helps explaining the observed differences in capabilities within our sample, we propose to enrich its analytical framework in order to adapt it to socio professional path study. Finally, the conducted analyzes lead us to split our sample into two groups: the ‘reluctant EDSW’ and the ‘fulfilled EDSW’. The reluctant EDSW, more numerous in Brazil, express a strong attachment to wage-labor, whereas the fulfilled EDSW see in EDSW position a way to exit disappointing jobs and often find benefits in a situation which offers them more autonomy than wage-labor and greater comfort than actual self-employment. Mobilizing the theoretical contributions of Fraser (2010) and Boltanski and Chiapello (2011), we demonstrate how the positioning of the fulfilled EDSW contributes to indirectly challenge the welfare state’s role.EDSW ultimately appear as an icon of an ambivalent process of individualization which contributes to the emergence of a subject who is seeking for autonomy, relieved from its traditional affiliations, while simultaneously promoting a direct confrontation of the individuals with the market that increases inequalities. Therefore, if the fulfilled EDSW’s wishes for emancipation and autonomy should be seriously considered, a reflection is needed on measures that may increase individual capabilities while struggling against increasing inequalities and maintaining a system of risks management based on solidarity. / Essa tese está dedicada a uma categoria específica de trabalhadores, os Trabalhadores Autônomos Economicamente Dependentes (TAEDs), que cumulam uma autonomia jurídica com uma situação de dependência econômica em relação a um único cliente. Ao associar características típicas das duas categorias clássicas que são os assalariados e os trabalhadores autônomos, os TAEDs inscrevem-se numa zona cinzenta do mercado de trabalho. A partir de uma pesquisa qualitativa realizada com TAEDs franceses e brasileiros do setor de Tecnologia da Informação, perguntamo-nos acerca do significado social dessa forma híbrida de trabalho e da sua emergência nos mercados de trabalho tão distintos da França e do Brasil. A análise das condições de trabalho dos entrevistados possibilita primeiro situar os TAEDs num continuum entre emprego assalariado e verdadeiro trabalho autônomo e diferenciar dois perfis: os prestadores integrados na estrutura cliente e os autônomos em transição. Para estudar as trajetórias profissionais desses trabalhadores, mobilizamos, em seguida, a abordagem pelas capacidades de Amartya Sen (2000): mostramos que os percursos dos TAEDs – que são privados das proteções trabalhistas pela sua autonomia jurídica – dependem de processos de acumulação e conversão de distintos tipos de recursos em liberdades reais (ou capacidades). Além disso, se a abordagem de Sen permite explicar as diferenças de capacidades observadas na nossa amostra, propomos enriquecer o seu marco de análise para adaptá-lo ao estudo de trajetórias socioprofissionais. As análises realizadas nos levam finalmente a distinguir dois grupos de entrevistados, os “TAEDs reticentes” e os “TAEDs satisfeitos”: os TAEDs reticentes, mais numerosos no Brasil, expressam um forte apego ao emprego assalariado enquanto os TAEDs satisfeitos veem na posição de TAED uma forma de se livrarem de empregos decepcionantes e, na maioria dos casos, creem vantajosa uma situação que oferece uma autonomia maior que o emprego assalariado e um conforto maior que o trabalho verdadeiramente autônomo. A partir das obras de Fraser (2010) e Boltanski e Chiapello (2011), mostramos que o posicionamento dos TAEDs satisfeitos questiona indiretamente o papel do Estado social. Os TAEDs aparecem então como uma figura emblemática de um processo ambivalente de individualização que contribui para a emergência de um sujeito que busca autonomia e está livre de seus pertencimentos tradicionais, ao mesmo tempo em que favorece um confronto direto do indivíduo com o mercado que aumenta as desigualdades. Se achamos que os desejos de emancipação e autonomia dos TAEDs satisfeitos têm que ser levados a serio, é necessário refletir sobre as medidas que poderiam expandir as capacidades dos indivíduos, lutando contra o aumento das desigualdades e preservando um sistema solidário de gestão dos riscos.