VictorJuiz/thesis huggingface dataset:
Characterization of the role of protein tyrosine phosphatase sigma (PTP[sigma]) in mammalian development

Protein tyrosine phosphatase sigma (PTPσ) is a member of the mammalian LAR family of phosphatases, which consists of three closely related proteins LAR, PTPδ and PTPσ. These phosphatases contain a cell adhesion molecule (CAM)-like ectodomain, a single pass transmembrane domain and two tandemly repeated intracellular phosphatase domains; the N terminal domain (D1) is catalytically active, and the C terminal domain (D2) is inactive. PTPσ expression is developmentally regulated in neuronal and epithelial tissues, and the PTPσ/PTPδ/LAR Drosophila homologue DLAR plays a crucial role in axonal pathfinding, which led us to speculate that PTPσ may serve an important function in the development of the mammalian nervous system, epithelialized tissues and organs. To study the role of PTPσ in mammalian development we generated and characterized full-length PTPσ knockout mice. The loss of the PTPσ protein results in abnormalities of the neuroendocrine, central and peripheral nervous systems. PTPσ(−/−) mice display pituitary hypoplasia, growth hormone (GH) and prolactin deficiencies. Functionally, the GH deficiency contributes to hypoglycemia and a high neonatal mortality rate, pancreatic islet hypoplasia and hypoinsulinemia. PTPσ deficient animals also display an altered glucose homeostasis. While the CNS of PTPσ(−/−) mice demonstrates the subtle abnormality of decreased choline acetyltransferase (ChAT) immunostaining, the PNS shows marked developmental delay and striking changes in regenerative growth. The loss of PTPσ increases the rate of sciatic nerve regeneration following injury, and results in significant axonal guidance errors. The lung, an epithelialized organ which strongly expresses PTPσ, appeared architecturally normal in the PTPσ(−/−) mice. We speculate that normal pulmonary development in the absence of PTPσ results from the compensatory action of the closely related LAR. The molecular mechanism by which the loss of PTPσ results in these abnormalities is not known. We demonstrated that the binding of PTPδD2 to PTPσD1 down regulates the catalytic activity of PTPσ, and suggested that heterodimerization may serve as a means by which to regulate the catalytic phosphatase activity of this family of enzymes. However, the target substrate(s) and signalling pathways in which PTPσ partakes remain unknown. In summary, PTPσ plays a crucial role in the development of mammalian neuroendocrine and neurologic systems.
Caring for persons with Alzheimer's disease: A Foucauldian analysis of an online support group

Foucault's concept on power relations and social governance were used to categorise textual data taken from the Canadian Alzheimer's discussion forum for family care providers in order to develop a theoretical understanding of how care givers use online support and the implication of its use on care provision. The majority of care givers conformed to the increased demands of care giving in Western society. They view care giving as an ethical exercise that requires personal sacrifice. In some instances, caregivers' accounts became politicized to protect the interest of persons with AD. Many resisted dominant health care discourses, acquired scientific knowledge and sought out alternative solutions. Online support can operate as a vehicle for disciplinary practices and social governance that in turn contributes to the construction of "enterprising" family care givers who independently seek out solutions and become self-sufficient masters in unremunerated care provision.
Regulation of Hedgehog signal transduction by Suppressor of fused through multiple mechanisms

During animal development, the Hedgehog (Hh) signal transduction pathway plays a key role in multiple processes including cell fate determination, tissue patterning and morphogenesis. In humans, aberrant Hh signaling has been linked to several genetic disorders and cancers. Hh signaling is ultimately mediated through the activities of the bi-functional Gli/Ci transcription factors. Previously, the mechanism of mammalian Hh signal transduction was extrapolated largely from observations in Drosophila. In this paradigm Suppressor of fused (Su(fu)), a novel protein, inhibits pathway activity by preventing the nuclear accumulation of Ci activator, but is dispensable for development. We have previously cloned mouse Su(fu) and demonstrated it plays a conserved role to inhibit Hh signaling in vitro. Furthermore, mutations in human Su(fu) were found associated with medulloblastoma, implicating Su(fu) as a tumor suppressor. In this thesis, I employ biochemical, cell biological and genetic approaches to investigate the mechanisms through which Su(fu) inhibits activity of the mammalian Gli genes (Glil-3). I find Su(fu) controls the subcellular localization of Gli1 and Gli2 through distinct mechanisms. Moreover, Su(fu) can inhibit Gli activity independent of sequestration, suggesting Su(fu) regulates Gli activity through both nuclear and cytoplasmic means. Loss-of-function analysis in mice revealed Su(fu) is indispensable for embryogenesis, acting as a critical rate-limiting factor to control pathway activity. My genetic and biochemical analyses demonstrated a role for Su(fu) to promote efficient processing of Gli3 into a transcriptional repressor. That Su(fu) promotes Gli repressor formation was unexpected as no similar role has been identified in flies. Significantly, preliminary analyses suggest that Su(fu) controls Gli3 processing through multiple mechanisms. Most notably, Su(fu) appears to facilitate efficient cAMP-dependent protein kinase-mediated phosphorylation of Gli3. Together this work uncovers important mechanistic insight into the regulation of mammalian Hh signaling and places Su(fu) in a central role as an inhibitory component acting through several mechanisms.
Teacher candidates' beliefs about including socioscientific issues in physics and chemistry

In this qualitative study 12 teacher candidates were interviewed at 3 points during a 9 month teacher education program: at the beginning of the course (in September), after the first practicum (in November) and after the second practicum (in March). Teacher candidates' beliefs did not change significantly from the beginning of the study to the end. They displayed varying degrees of commitment to including SSI in their teaching. Based on their (a) conception of the ethics of science, (b) goals for science education, (c) idea of the place of ethics in science (education), and (d) beliefs about including SSI, the teacher candidates were divided into four groups. Four archetypes were derived: "Model Scientist/Engineer", "Model Individual", "Model Teacher", and "Model Citizen". Since these groups are archetypes, none of the participants fits into the categories perfectly but individual teacher candidates demonstrated more characteristics of one archetype than others. Only the 3 Model Citizens were committed to including SSI in their teaching while the others placed the priority on preparing students for the next level of schooling. Teaching science for social justice involves a deliberate effort to reconstruct society into something more equitable and just. Introducing socioscientific issues (SSI) into science is one strategy toward this end. However, research indicates that SSI are rarely discussed in the physical sciences even though they exist. This may be due to the beliefs of chemistry and physics teachers with respect to what belongs in these subjects. If we wish to begin to influence these beliefs through initial teacher education, it is essential for teacher educators to understand the origins of these beliefs. A model was developed to serve as a microgeneology of teacher candidates' beliefs about including SSI in their teaching. It traced their beliefs from (a) life experiences to (b) conception of ethics and nature of science to (c) goals for science education to (d) inclusion or non-inclusion of SSI. Based on the archetypes, current beliefs were extrapolated into future beliefs. How teacher educators could use this model to influence the future beliefs of their students is discussed.

Keywords: Student teachers, Attitudes
Physics teachers, Attitudes
Chemistry teachers, Attitudes
Physics, Social aspects
Chemistry, Social aspects
Science, Social aspects
Stochastic decentralized systems

Fundamental aspects of decentralized systems are considered from a control perspective. The stochastic framework afforded by Markov systems is presented as a formal setting in which to study decentralized systems. A stochastic algebra is introduced which allows Markov systems to be considered in matrix format but also strikes an important connection to the classic linear system originally studied by Kalman [1960]. The process of decentralization is shown to impose constraints on observability and controllability of a system. However, it is argued that communicating decentralized controllers can implement any control law possible with a centralized controller. Communication is shown to serve a dual role, both enabling sensor data to be shared and actions to be coordinated. The viabilities of these two types of communication are tested on a real network of mobile robots where they are found to be successful at a variety of tasks. Action coordination is reframed as a decentralized decision making process whereupon stochastic cellular automata (SCA) are introduced as a model. Through studies of SCA it is found that coordination in a group of arbitrarily and sparsely connected agents is possible using simple rules. The resulting stochastic mechanism may be immediately used as a practical decentralized decision making tool (it is tested on a group of mobile robots) but, it furthermore provides insight into the general features of self-organizing systems.
Gene amplification of asparagine synthetase in albizziin-resistant Chinese hamster ovary cells

In this thesis I have investigated the events that occurred during the amplification of Asparagine synthetase in a series of single- and multi-step albizziin-resistant Chinese hamster cell lines. The main goal of this work was to test the various models of gene amplification in the literature. Chapter 1 is a survey of the literature with emphasis on models of amplification, the structures associated with amplified sequences, and the role of amplification in drug resistance and tumor development. Chapter 2 is an analysis of the drug resistant phenotype in the Alb R cell lines. Single-step mutants had 3 to 9 fold increases in their copy numbers of AS while multi-step mutants had increases up to 83 fold over the wild type. In all of these lines the increase in AS RNA was higher than the levels of amplification. This difference was related to a demethylation of the 5′ region of the gene. Chapter 3 describes the structure and organization of the AS amplicons in the different single- and multi-step AlbR mutants. Pulse field gel electrophoresis studies revealed that large homogeneous structures (>2.7 Mb) were involved in early and some later events in the amplification of AS in these mutants. Fluorescent in situ hybridization analysis localized these amplicons to the wild type locus, 1q, in the cell lines with these large structures. The results of these studies were consistent with an unequal exchange mechanism involving large subchromosomal regions of 1q, mediating the early events in the gene amplification of AS. Chapter 4 contains a discussion of recent fluorescent in situ hybridization studies on gene amplification. The results of this work are discussed in relation to these current reports.
The relationship between mandibular growth and cervical vertebral maturation in males

Objective. To establish a pattern of mandibular growth and relate it to the stages of cervical vertebral maturation. Methods. Yearly cephalometric radiographs, ages 9-18, were evaluated for 90 males. Mandibular lengths were measured and incremental growth determined. Cervical vertebral maturation stages were assessed using the 6 stage method. Advanced, average and delayed maturation groups were established. Results. The pre-pubertal mandibular growth minimum occurs during cervical stages 1 through 4 (p
Effects of repeated antenatal dexamethasone (dex) exposure on hypothalamic-pituitary-adrenal (HPA) function in mature adult guinea pigs (Cavis porcellus)

We examined the effects of antenatal glucocorticoid treatment on mature adult hypothalamic-pituitary-adrenal (HPA) function in guinea pigs. Pregnant guinea pigs were treated with dexamethasone or vehicle on days 40/41, 50/51 and 60/61 of gestation, after which animals delivered normally. Offspring were catheterized at 145 days of age and subjected to tests of HPA axis function. Male offspring exposed to dexamethasone in utero exhibited decreased basal cortisol, increased HPA sensitivity to challenge, increased hippocampus to brain weight ratio, increased adrenal to body weight ratio and increased mean arterial pressure. Female offspring born to dex-treated mothers showed a significant increase in basal cortisol during the low progesterone phase and an increase in HPA sensitivity irrespective of progesterone. Changes in endocrine data were consistent with changes in mineralocorticoid receptor in the limbic system and glucocorticoid receptor in the pituitary. In conclusion, repeated antenatal glucocorticoid exposure permanently modifies offspring HPA function in sex-specific manner.
Describing the crisis experience for individuals with severe and persistent mental illness

This qualitative study investigated the crisis phenomenon for individuals with severe and persistent mental illness (SPMI). Intensive in-depth semi-structured interviews were conducted with fourteen individuals with SPMI. Grounded theory techniques were used to analyze the data and develop a theory of the crisis phenomenon. Results showed that an underlying vulnerability exists in individuals with SPMI which sets the stage for crisis occurrence, crisis experiences involve feeling overwhelmed and lacking control, and these experiences can manifest as episodes of agitation/anger/aggression, being low, feeling anxious, or euphoria. Immediate responses to crises involve either getting help or managing alone and there are a variety of processes for crisis resolution and prevention. Suicidality generally emerged as a separate phenomenon. It was concluded that the crisis experience for individuals with SPMI does not fit within the traditional model of crisis. Implications for supporting individuals with SPMI are provided.
Adjustment processes of four infants attending centre daycare

This study used a phenomenologically based case study participant-observation approach to examine adjustment processes of 4 babies to a university daycare centre utilizing a primary caregiver model. The study included 2 girls and 2 boys, ranging in age at entrance from 5 1/2 to 10 months. At least 3 semi-structured interviews were conducted with parents and teachers. Within the context of this study, an adjustment model is presented that describes a progressive, dynamic and fluid sequencing of processes that overlap and interact interdependently. Successful adjustment involves a transfer of a sense of containment and security derived from familiar people, objects and routines to new people, objects and routines in a new environment and includes the development of an attachment to the primary caregiver. The model describes how attachment developments and adjustment processes affect the family, infant and daycare teachers as they interact in the larger caregiving system. Containment of the baby's distress is the key factor in this transfer process. Development of cooperative, attuned care by the parents and teachers is the most effective means to provide this containment. Seven major factors are identified that affect containment (parent-teacher comfort level, attunement to babies' needs, prior caregiving history, developmental issues, babies' ability to cope with stress, experiences of loss) and twelve major criteria are derived for the accomplishment of adjustment. Adequate experiences of containment allow the babies to be more open to take in and learn about their new environment. Inadequate containment experiences disrupt adjustment by creating a build-up of distress in the babies, leading to regression. The first five factors facilitate or impede adjustment depending on whether they support or disrupt containment for the babies. The sixth and seventh factors—loss and illness—always disrupt containment, and thus always lead to a derailment of the adjustment process, although less so following the babies' internalization of caregiver containment. Support for the findings in the daycare and theoretical literature are discussed. Six areas of importance for future research are presented.

Keywords: Infants, Development
Child development
Eye-hand coordination in infants
Infants, Growth
Child rearing
Day care centers
Child care services
Optimization of a two-step process for the production of ASTM-standard biodiesel from refurbished oils and fats

Biodiesel can be produced from low cost feedstock such as refurbished waste fats and oil, which contain significant amounts of free fatty acid (FFA), by using two-step process. The first step converts the FFA by acid catalysis, and the second step converts the triglycerides (TG) by base catalysis. Currently, the major challenge for the industrial production of biodiesel is to optimize biodiesel yield and meet ASTM standards. Experiments have been performed to optimize the reaction conditions. The process variables studied were: FFA content in feedstock, water content, type and amount of acid catalysts, type of base catalysts, salts and their types, and temperature. The experimental parameters studied were: (1) FFA content (0, 10, 15, 20, 30, and 50 mass%), (2) H2SO4 (1.0 and 2.0 wt% of feed) and HCl (0.74 wt% of feed), (3) NaOH (1.0 wt%), KOH (1.4 wt%), and NaOCH3 (1.35 wt% of feed), (4) temperature for the acid step (60°C), and for the base step 23°C and 40°C), (5) water content (water produced from neutralization, and water produced from neutralization as well as from 20% FFA). The optimum conditions found were: (1) FFA content up to 10–15% max., (2) H2SO 4 (1.0 wt%) and HCl (0.74 wt%), (3) NaOH (1.0 wt%), NaOCH 3 (1.35 wt%), and KOH (1.4 wt%), (4) acid step temperature (60°C) and base step temperature (23°C), and Feed/THF/CH3OH volume ratio 1:1:1. These conditions produced biodiesel, which meets ASTM standards.
The role of serine phosphorylation on the slow inactivation of the GluR1 Lurcher AMPA receptor

AMPA receptors are the main fast excitatory neurotransmitter receptors in the CNS. The Lurcher mutation is a single amino acid switch that occurs in glutamate receptor subunits. When introduced to the GluR1 glutamate receptor subunit, the Lurcher mutation (GluR1Lc) results in constitutively active channels that undergo a slow process of inactivation that is not seen in wild type channels. GluR1 subunits are phosphorylated by PKC (at Ser831) and PKA (at Ser845). In the present study 1 evaluated the rote of GluR1Lc phosphorylation on the rate of receptor inactivation. Activation of PKC resulted in decreased rates of inactivation, while blocking PKC resulted in increased inactivation rates. Blocking the phosphatase calcineurin resulted in increased inactivation rates. Western blot analysis showed that phosphorylation of Ser831 increases with induction of inactivation while Ser845 phosphorylation decreases. This study implies that the state of phosphorylation of GluR1Lc receptors dictates the rate of receptor inactivation.
Application of nanocrystalline metals in microsystem fabrication

This research addresses the issues of performance variability and reliability concerns frequently encountered with conventional metallic microsystem components (e.g. MEMS) produced by electrodeposition methods such as LIGA. Previous studies have demonstrated that microsystem components produced by conventional electrodeposition approaches show relatively low overall hardness and considerable variations in Young's modulus and hardness throughout the cross-section of the components. In this work, this undesirable property variability has been traced back to microstructural and scaling effects. It has been shown that the microstructure of conventional deposits exhibits grain size gradients resulting from a fine grained to columnar structure transition with increasing component thickness. In addition, the overall component size is often comparable to the relatively large grain size in these deposits. In past efforts, both post-deposition recrystallization annealing and texture control during the electroplating process have been used in efforts to alleviate these concerns, however only with some limited success. In this research, a new approach is used which essentially involves the application of an electrodeposition process that produces fully dense nanostructured deposits throughout the entire cross-section of the component without the transition from fine to large grained columnar structure. The cross-sectional microstructures and mechanical properties (i.e. hardness and Young's modulus) are presented for electrodeposited nickel and cobalt foils with conventional polycrystalline and nanocrystalline structures as well as nanocrystalline nickel plated in molds with non-conductive side-walls prepared by the UV-photolithography molding process. Microstructural characterization was performed on these materials using scanning electron microscopy (SEM), optical microscopy, back scattered electron imaging (BSEI), and transmission electron microscopy (TEM) as well as orientation imaging microscopy (OIM) and X-Ray diffraction (XRD) analysis for crystallographic texture measurements. The mechanical properties of all deposits were evaluated using the nanoindentation technique. It is shown that nanocrystalline electrodeposits exhibit considerably improved cross-sectional properties both in terms of uniformity (hardness and Young's modulus) and overall hardness level. These properties result in higher performance indicators for microsystem components such as specific strength, elastic energy storage capacity, and wear resistance as compared with conventional components. In this thesis this was demonstrated for the specific case of Ni electrodeposits.