Doctor of Philosophy

dissertationA cell's morphology plays an important role in its function. Thus, the size, shape, and structure of cells can be strikingly different across biology. In order to create this variation, cells must divide and differentiate in specific and regulated ways. In this dissertation, I describe work using C. elegans sperm to understand the programs controlling development of specialized cells. During development, sperm undergo meiotic division and differentiation to become polarized, motile, and capable of fusing with oocytes. From studying these processes, I identified two genes that are important both for sperm development and in contexts beyond reproductive biology. The first chapters of this dissertation describe a new function for the conserved t-SNARE syntaxin 7 (syx-7) in cytokinesis, the process that separates cells from one another following nuclear division. Without syx-7, sperm complete most steps of division, but the final abscission fails. During cytokinesis in animal cells, an actin ring forms between newly partitioning cells. However, it is not currently understood how vesicle traffic is spatiotemporally coupled to actin during cytokinesis. As syx-7 sperm progress through division, actin becomes mislocalized, providing one of the first examples of a specific component of vesicle trafficking machinery with an impact on actin localization during cytokinesis. Additionally, a specialized lysosome-like organelle is disrupted in syx-7 sperm, raising interesting questions about the link between this family of organelles and cell division. If a functional contribution is established, this would represent a new role for lysosome-like organelles, which, when disrupted, cause several human disorders. The later chapters of this work focus on the final steps of sperm differentiation: cell polarization and acquisition of motility. Our lab identified a signaling pathway that induces sperm motility in response to an extracellular protease. Here, I describe discovery of snf-10, a Solute Carrier 6 (SLC6) family gene, which provides the first link connecting the protease signal to changes in sperm physiology, and ultimately motility. Positive regulation by a protease is a novel finding for a member of the SLC6 family, a group of genes that have numerous roles in human physiology, but have been studied in limited contexts

New Measurements of the EMC Effect in Few-Body Nuclei

Measurements of the EMC effect show that the quark distributions in nuclei are not simply the sum of the quark distributions of the constituent nucleons. However, interpretation of the EMC effect is limited by the lack of a reliable baseline calculation of the effects of Fermi motion and nucleon binding. We present preliminary results from JLab experiment E03-103, a precise measurement of the EMC effect in few-body and heavy nuclei. These data emphasize the large-x region, where binding and Fermi motion effects dominate, and thus will provide much better constraints on the effects of binding. These data will also allow for comparisons to calculations for few-body nuclei, where the uncertainty in the nuclear structure is minimized.Comment: Proceedings from talk at the Topical Group on Hadron Physics meeting, Nashville Tennessee, October 22-24, 2006. 9 pages, 6 figure

The dopaminergic midbrain participates in human episodic memory formation: Evidence from genetic imaging

Recent data from animal studies raise the possibility that dopaminergic neuromodulation promotes the encoding of novel stimuli. We investigated a possible role for the dopaminergic midbrain in human episodic memory by measuring how polymorphisms in dopamine clearance pathways affect encoding-related brain activity (functional magnetic resonance imaging) in an episodic memory task. In 51 young, healthy adults, successful episodic encoding was associated with activation of the substantia nigra. This midbrain activation was modulated by a functional variable number of tandem repeat (VNTR) polymorphism in the dopamine transporter (DAT1) gene. Despite no differences in memory performance between genotype groups, carriers of the (low expressing) 9-repeat allele of the DAT1 VNTR showed relatively higher midbrain activation when compared with subjects homozygous for the 10-repeat allele, who express DAT1 at higher levels. The catechol-O-methyl transferase (COMT) Val108/158Met polymorphism, which is known to modulate enzyme activity, affected encoding-related activity in the right prefrontal cortex (PFC) and in occipital brain regions but not in the midbrain. Moreover, subjects homozygous for the (low activity) Met allele showed stronger functional coupling between the PFC and the hippocampus during encoding. Our finding that genetic variations in the dopamine clearance pathways affect encoding-related activation patterns in midbrain and PFC provides strong support for a role of dopaminergic neuromodulation in human episodic memory formation. It also supports the hypothesis of anatomically and functionally distinct roles for DAT1 and COMT in dopamine metabolism, with DAT1 modulating rapid, phasic midbrain activity and COMT being particularly involved in prefrontal dopamine clearance

State of Wet Tropics Report 2015-2016: ancient, endemic, rare and threatened vertebrates of the wet tropics

Each year the Wet Tropics Management Authority prepares a report on the administration of the Act during the year, financial statements for the year, and a report on the state of the Wet Tropics World Heritage Area. This State of Wet Tropics report satisfies the requirements of Queensland's Wet Tropics World Heritage Protection and Management Act 1993 and the Commonwealth's Wet Tropics of Queensland World Heritage Conservation Act 1994

L'espace : un mode de gestion de la dynamique organisationnelle

It is often difficult to inscribe space management in the decision-making process of firms: overlaps in organizational and spatial issues obscure the basic questions at stake in their articulations, and knowledge brought to bear in the planning stage proves to be partial, notably in the face of change. But malfunctioning and the efforts of occupants to adapt to a workplace have their cost, which executives rarely take into account.Working from a question: ‘How can we analyse the contribution of space management in the pursuit of objectives of organization?’, and from the field: a department undergoing change in a firm, our research attempted to address this difficulty. The observation of work-place design intended to respond to a managerial project, of the subsequent uses and changes in managerial orientations, and of the new interpretations that follow show the evolution of relations between organization and space, the changes and breaks as well as the uninterrupted elaboration of representations.Informed by the cognitive approach of organized bodies, the concepts used to analyse the field study enable us to apprehend the reciprocal nature of exchanges between resources and the elaboration of compromises between the various objectives pursued and the means made available in the course of a collective action. Space thus appears as a resource that can make a very positive contribution to the construction and negotiation of meaning in collective action. It is in this spirit that we propose the concept of figuration whereby space carries, by way of representation, a sum of knowledge that is directly or indirectly linked to the appropriateness between the action addressed and the physical facilities.The management of spatial resources, apart from adjusting physical facilities and organization according to the objectives pursued, thus includes negotiation with the ‘real’ in the course of action. We may thus envisage the question of space on one hand as a continuity moving to and fro between the objectivization of representations and their inscription in form, and on the other hand as a figuration, which consists in situating action.Il apparaît souvent difficile d’inscrire la gestion de l’espace dans le processus de décision des organisations : l’imbrication des dimensions organisationnelles et spatiales induit une forte opacité de leurs articulations et les savoirs mobilisés s’avèrent partiels, notamment face aux changements. Le dysfonctionnement et l’effort des occupants pour s’adapter au lieu ont pourtant un coût que le management mesure rarement. A partir d’une question : « Comment analyser la contribution de la gestion de l’espace à la poursuite des objectifs d’une organisation ? » et d’un terrain : un service d’entreprise en changement, c’est à cette difficulté que notre recherche s’est confrontée. L’observation de l’aménagement du lieu pour répondre au projet managérial, puis des usages, de la modification des orientations managériales et des nouvelles interprétations qui ont suivies montre l’évolution des relations entre l’organisation et son espace, leurs modifications, leurs ruptures et l’élaboration ininterrompue des représentations.Stimulés par l’approche cognitive des organisations, les concepts mobilisés lors de l’analyse du terrain ont permis d’appréhender la réciprocité des échanges entre les ressources et l’élaboration de compromis entre les diverses finalités poursuivies et les moyens disponibles au cours de l’action collective. L’espace apparaît alors comme une ressource pouvant contribuer à la construction et à la négociation du sens dans l’action collective. C’est dans cet esprit que nous avons proposé le concept de figuration lorsque l’espace véhicule, à travers la représentation, un ensemble de connaissances directement ou indirectement liées à l’adéquation entre l’action et le dispositif matériel. La gestion de la ressource spatiale, outre l’ajustement entre le dispositif matériel et l’organisation en fonction des objectifs poursuivis, comprend donc la négociation sur le « réel » au cours de l’action. On peut alors envisager la gestion de l’espace comme une continuité dans l’aller-retour entre l’objectivation des représentations et leur inscription dans la forme, d’une part, et d’autre part la figuration qui consiste à situer l’action

Precise Measurement of the β-Asymmetry in the Decay of Magneto-Optically Trapped, Spin-Polarized 37K

Precise low-energy measurements in nuclear β-decay provide constraints on possible physics beyond the standard model complementary to high-energy collider experiments. This thesis describes the most precise measurement of the positron asymmetry from a polarized nucleus to date. At the TRIUMF Neutral Atom Trap, atoms of the positron emitter 37K are confined in an alternating-current magneto-optical trap and spin-polarized to 99.13(9)% via optical pumping. The use of atom-trapping techniques allow for an exceptionally open geometry with the decay products escaping the trapping region unperturbed by the trapping potential. The emitted positrons are detected in a pair of symmetric detectors placed along the polarization axis to measure the asymmetry. The analysis was performed blind and considers β-scattering and other systematic effects. The result, Aβ (0) = −0.5707 ± 0.0018, places limits on the mass of a hypothetical W boson coupling to right-handed neutrinos to be > 300GeV/c^2 at zero-mixing as well as contributes to an independent determination of the Vud element of the CKM matrix

O gerenciamento de processos pelo juiz à luz do Código de Processo Civil de 2015

O presente estudo visa à análise da viabilidade do gerenciamento de processos no ordenamento jurídico brasileiro como instrumento para os juízes na efetivação da tutela constitucionalmente prevista. Para tanto, foi empregado o método dedutivo e analisado o tema a partir de subsídios doutrinários e legais. O escopo deste trabalho é comprovar que, muito embora em nosso ordenamento jurídico não haja uma sistematização especifica sobre o assunto, a atuação ativa do juiz é resguardada por uma série de mecanismos legalmente previstos que propiciam a gestão processual como estratégia à otimização do judiciário. O objetivo inicial é explanar a base do gerenciamento de processos, com a exposição de sua conceituação, finalidades, princípios legitimadores e realizar breves considerações sobre os limites encontrados a sua aplicação. Posteriormente se deterá ao estudo do direito estrangeiro, mais especificadamente aos sistemas norte-americano e inglês, acentuando-se as contribuições incorporadas ao direito pátrio. Por fim, se perquirirá as principais e mais viáveis técnicas propiciadas pelo Código de Processo Civil de 2015 à gestão de processos.The present study aims to analyze the feasibility of case management in the Brazilian legal system as an instrument for judges in the implementation of the constitutional order. The deductive method was utilized together with the analyzes of doctrinal and legal subsidies. The scope of this study is to prove that, despite the fact that there is no specific systematization of the subject in our legal system, the active role of the judge is protected by a series of legally provided mechanisms that enable a procedural management as a strategy for the optimization of the judiciary. The initial objective is to explain the basis of process management, with an explanation of its concepts, purposes, legitimating principles and limits found in its application. Subsequently, the study of foreign law will focus more specifically on the US and English systems, emphasizing the gestational techniques that have been incorporated into national law. Finally, the most viable techniques provided by the Brazilian 2015 Code of Civil Procedure for this purpose will be examined