VictorJuiz/thesis huggingface dataset:
In vivo role of PTEN in pancreatic beta cell homeostasis and whole body growth

PTEN (phosphatase with tensin homology) is a potent negative regulator of P13K/Akt signaling, an evolutionarily conserved pathway that signals downstream of growth factors including insulin and IGF-1. Recently, rodent insulin transcription was also shown in the brain, particularly the hypothalamus. The specific regulatory elements of the P13K pathway in these insulin-expressing tissues that contribute to growth and metabolism in higher organisms are unknown. Here, we report PTEN as a critical determinant of body size and glucose metabolism when targeting is driven by the rat insulin promoter in mice. Partial deletion of PTEN in hypothalamus resulted in significant whole body growth restriction and increased insulin sensitivity. Efficient PTEN deletion in beta cells led to increased islet mass without compromise of beta cell function. Parallel enhancement in P13K signaling was found in PTEN-deficient hypothalamus and beta cells. Together, we have shown that PTEN in the insulin transcribing cells may play an integrative role in regulating growth and metabolism in vivo.
An FPGA implementation of face detection and lip feature extraction

Lip motion has been used in speech separation to enhance the speech signal of interest or directly in speech recognition to improve the recognition accuracy. This thesis presents new techniques in face detection and lip feature extraction, both of which are prerequisite to the use of lip motion. In the face detection technique, the fact that faces have strong edges around the facial features is exploited to significantly reduce the model's size to 5.06Kbytes, yet achieving the detection rate of 87.2% under various lighting conditions. This allows us to build a compact hardware system. The lip feature extraction technique uses the contrast around the lip contour to extract the height and width of the mouth - two important parameters in speech separation. An FPGA implementation is presented, that occupies 15,050 logic cells, or about 6 times less than the current leading FPGA face detection system.
Domestic services: Employer-employee relationships under economic reforms in urban Vietnam

This dissertation examines employer-employee relationships in domestic services in urban Hanoi in order to contribute to a fuller understanding of gender and class relations under economic reforms in Vietnam since 1986. Ethnographic fieldwork was conducted with 24 female domestic workers and their employers, owners of domestic employment agencies, rural recruiters, former domestic workers, domestics' relatives in Hanoi and in Vinh Phuc province. I argue that due to a gender bias in state policies and local discourses, both female domestic workers and their female employers have suffered similarly from economic reforms. The withdrawal of state subsidies in health, education and social services has shifted more burdens to households and specifically to women in the context of local definitions of women's family responsibilities. A number of rural women have become domestic workers, and many urban women, their employers, in order to fulfill their family duties. Both groups of women tend to define themselves in terms of the four feminine virtues and struggle with the image of women both good at paid work and excelling at home. Negotiation and resistance occur when women get involved in domestics service as domestics and employers. The emphasis on harmonious relationships in Vietnamese culture, rooted in Confucianism, tends to obscure the actual relations of class conflict and struggle that are integral to employer-employee relationships. Although the class concept is typically not used to explain problems and conflicts, they are underlain by some class awareness and class struggle which are partially obscured because the boundary between employers and domestics is not always clear cut. I argue that domestic services in urban Hanoi need to be understood within the context of the political economy of gender and class relations under economic reforms. This dissertation contributes to the fields of gender studies, sociology, political economy, Vietnamese studies, and to the study of the restructuring of contemporary nation-states and societies under neo-liberal reforms. It hopes to provide useful information to scholars interested in Vietnam and domestic work, as well as to policy makers, planners, and activists who would like to "make" domestics more visible in a labour market through legal reforms.
Nutrient limitation of plant growth and forage quality in Arctic coastal marshes

As their preferred salt-marsh habitats have become degraded in recent years, lesser snow geese at La Pérouse Bay, Manitoba, have increasingly utilized alternative forage species and freshwater habitats. Above-ground net primary productivity in the salt marsh and the freshwater marsh is nitrogen- and phosphorus-limited respectively, based on soil analyses and fertilization experiments. This indicates that goose fecal deposits, which are rich in nitrogen, will not increase forage availability in the freshwater marsh. Declines in nitrogen and phosphorus use efficiencies of forage plants occur in fertilized plots. Preferred forage species have higher nutrient concentrations than either alternative or non-forage species, and lower carbon: nitrogen and carbon: phosphorus ratios. Overall, these results suggest that the geese are increasing obtaining forage of lower nutritional quality, which may contribute to the recorded decline in gosling size and survivorship.
Potential effects of climate change on the invasion of largemouth bass (Micropterus salmoides) in Lake Tahoe, California-Nevada

Warming of the Earth's climate will promote the spread of some nonnative species into novel territories and affect native populations inhabited in these areas. In this thesis, I draw on the recent invasion of largemouth bass in Lake Tahoe, California-Nevada as a case study to develop a practical approach to examine and quantify the impact of climate change on the resistance of large, high elevation lakes to invasion by warmwater fish species. In Chapter 2, I predict that surface water temperature of Lake Tahoe will increase by as much as 3°C by 2080--2099. In Chapter 3, I demonstrate that such an increase will significantly alter the thermal suitability of Lake Tahoe for largemouth bass, both temporally and spatially. My analysis suggests that further range expansion of largemouth bass is highly probable and all of the Lake Tahoe's littoral zones will become suitable for bass by 2080 in some years.

Keywords: Largemouth bass, Tahoe, Lake (Calif. and Nev.)
Largemouth bass, Climatic factors
Introduced fishes, Tahoe, Lake (Calif. and Nev.)
Introduced fishes, Climatic factors
Characterization of Bacillus anthracis lethal factor

Anthrax lethal toxin (LeTx), consisting of protective antigen and lethal factor (LF), is a principal virulence factor of Bacillus anthracis. LF represents the enzymatic component of LeTx and its cytosolic targets are members of the mitogen activated protein kinase kinase (MEK) family. It is currently not known if MEKs play a role in the intoxication process. To address this question, a screen of C-terminal LF mutants was performed to isolate mutants defective at killing macrophages. One such isolated mutant, LF-K518E/E682G, was characterized and found to be defective at cleaving MEK 3b but was able to cleave MEKs 1 and 4. Furthermore, LF-K518E/E682G was unable to downregulate phosphorylation of the MAPKs p38 and JNK. The ability of LF-K518E/E682G to downregulate the phosphorylation of ERK was retained. These results collectively provide further support for the importance of the p38 pathway in LF-mediated macrophage killing and suggest the involvement of the JNK pathway.
Narrative beyond teaching: inquiry into the shifting identity, culture and professional practice of five visible minority immigrant teachers in a diverse lifespace

This is a narrative inquiry into the identity development, cultural and professional transformation of five visible minority teachers before and after immigrating to Canada. The teacher participants, Dave, Beneth, Lily, Ann and I migrated to Canada during the 1990s from Africa, the Philippines, Egypt and Hong Kong. We worked in other careers before completing pre-service teacher education and became teachers in Ontario. As the student population in many Canadian schools is increasingly multiracial and multilingual, there is a growing demand for teachers from diverse cultures. Within the past ten years, five of us were recruited by a southern Ontario school board to teach in its elementary and secondary schools. We encountered major changes in life and experienced differences in Canadian society. Through storytelling, Dave, Beneth, Lily, Ann and I relived our childhood history in our homelands, re-told our lives as new immigrants in Canadian society, recalled the processes of changing professions to become educators and uncovered our teacher narratives in the multicultural school landscape. This study explores the implication of identity shifts in re-shaping our personal and professional lives. Upon reflections, we re-discover 'who we are' as visible minority immigrant teachers and re-examined how our ethnic, cultural and linguistic differences impact on teaching and teacher-student-parent relationship. Throughout the inquiry, narrative is studied as both phenomenon and method. Identity is understood as 'stories to live by' which take shape as life unfolds (Connelly & Clandinin, 1999). The teachers' experiences are made meaningful by bringing forward the past account, present encountering and future intention in different social and cultural contexts. As visible minority teachers, we deem to maintain a harmony of both Canadian culture and individual ethnicity. This narrative inquiry supports and builds on the perspective that teachers use their knowledge and individual stories in their teaching practice. It underlines the contributions of visible minority teachers to the academic success and personal growth of students from minority population. The teachers' stories broaden our understanding of the school cultures within which they live and work. The implications for teacher education, professional development and educational planning are explored in the light of the narratives.
Fluoride-laser microfabrication of diffractive optical elements

The 157nm F2-laser drives strong and precisely controllable interactions with fused silica, the most widely used material for bulk optics, optical fibers, and planar optical circuits. A Diffractive Optical Element (DOE) changes wavefronts by redirecting segmented beamlets through phase control. DOE applications include optical computing, laser machining, optical communications, and biological sensors. Precise excisions of 10--30 nm depth are available for the generation of efficient DOEs for the visible and ultraviolet spectrum. F2-laser radiation was applied with beam homogenization optics and high-precision computer-controlled motion stages to shape up to 16-level 256 x 256 pixels DOE devices in bulk glasses, with distinguishable level-to-level spacing of sim;100 nm and surface roughness of sim;3 nm. The 1 st order diffraction efficiency was sim;36--42%. The farfield pattern when illuminated with a HeNe laser agreed well with iterative Fourier Transform algorithm simulations. Future improvements in the laser micromachining process and possible directions are also offered.
Preclinical evaluation of inhibitors of the phosphatidylinositide 3-kinase/protein kinase B cell survival pathway in the treatment of pancreatic cancer

Pancreatic cancer is resistant to almost all classes of cytotoxic drugs. Gemcitabine appears to be the current drug of choice. However, even with this drug, the objective response rate is less than 20%. Patients often die within 6 months after diagnosis. Novel treatment strategies are urgently needed to improve quality of life and reduce mortality. The hypothesis being tested in this thesis is that cell survival signals transmitted via phosphatidylinositide 3-kinase (PI3K) and protein kinase B (PKB/Akt) may play a significant role in mediating drug resistance seen in pancreatic cancers. Agents that perturb this survival pathway are therefore predicted to demonstrate therapeutic potential. To optimize the use of these experimental inhibitors in chemotherapy, a better understanding of their in vivo pharmacodynamics in pancreatic cancers is required. Studies were designed to examine the effects of the prototype PI3K inhibitors wortmannin and LY294002 on drug sensitivity in cultured human pancreatic cancer cell lines PK1 and PK8. Both agents suppressed PKB/Akt phosphorylation and enhanced gemcitabine-induced apoptosis. Subsequently, an orthotopic xenograft model was established by injecting PK1 cell suspensions into the pancreas of severely combined immunodeficient (SCID) mice, and used to determine the in vivo duration of action and dose-response profile of wortmannin. Phosphorylated PKB/Akt levels were decreased in a time- and dose-dependent manner by the drug in the orthotopic tumors in situ. Also, the combined use of wortmannin and gemcitabine produced more significant increase in apoptosis and inhibition of tumor growth than either agent used alone. To examine how far these findings can be generalized in the clinical situation, a panel of primary pancreatic cancer xenografts were established in SCID mice to study response profiles to the epidermal growth factor receptor inhibitor OSI-774 alone and in various drug combinations. OSI-774 significantly blocked epidermal growth factor receptor activation but failed to reduce phosphorylated PKB/Akt levels in the two patient xenografts tested, and decreased phosphorylated mitogen-activated protein kinase levels in one patient xenograft but not the other. The combination of OSI-774 and wortmannin plus gemcitabine further increased apoptosis compared to wortmannin plus gemcitabine. Such variability and complexity of responses to combinatorial treatments likely reflect the clinical situation, and may be attributed to differential genetic background of tumors from different patients. Taken together, findings of this thesis have provided evidence on the role of the PI3K-PKB/Akt cell survival pathway in mediating drug resistance in pancreatic cancer in vivo and supported the use of its inhibitors as adjuncts to conventional chemotherapy in the treatment of this malignancy. By characterizing a patient's tumor, the efficacy of treatment regimens involving multiple signal transduction inhibitors may be further optimized.
A co-evolutionary approach to aerial combat games

In this thesis, a new numerical method, the Host-and-Parasite Particle Swarm Optimization (HPPSO), is presented to solve pursuit-evasion games and to approximate the solutions to two-target dogfight problems. Mimicking the biological phenomenon of parasites infesting their hosts, HPPSO solves max-min problems by embedding a series of particle swarm optimizer (PSO) inside another PSO at a higher level. Our results showed that HPPSO performed well in solving different pursuit-evasion problems. For two-target dogfight games, HPPSO is also able to yield realistic solutions to many of the cases we studied.
Essays on outsourcing and hold-up

This thesis consists of three essays on topics concerning the hold-up problem and outsourcing. Chapter 1 asks whether the hold-up problem is crucial in shaping firm boundaries. I present a holdup model and prove that the under-investment problem can be solved if the surplus from an up-front investment accrues in more than one period and the investing party has a chance to terminate the flow of surplus from the investment prior to its full realization. The result suggests that hold-up need not be a major impediment to arm's length transactions. Chapter 2 develops a model that illustrates firms outsource in order to pool risk. I first analyze the sources of surplus from risk-pooling. I then explicitly study three common outsourcing contracts and evaluate their performance in terms of pooling risk under different information structures. The result suggests that risk-pooling can be one of the motives for outsourcing. However, whether outsourcing can be efficient in pooling risk depends crucially on the information structures. Chapter 3 argues that foreign competition is the main driving force for the dramatic increase in cognitive skill requirements in U.S. since the early 70s. There are theoretical arguments in support of foreign competition changing skill requirements through its effects on capital deepening. Using data from the Dictionary of Occupational Titles, we construct various weighted skills requirement measures from 1971 to 2001. We observe three empirical regularities: (1) While the average skill requirements of occupations in the U.S. economy shifted towards more cognitive skills and away from manual skills, this trend happened significantly more dramatically in the manufacturing sector than in the non-manufacturing sector. (2) Manufacturing industries that were more exposed to foreign competition accumulated more capital over time. (3) Foreign competition changes skill requirements primarily through its effect on capital deepening.
Functional consequences of calcium signaling by dopamine D1 and D2 receptor hetero-oligomers

There is extensive evidence pointing to the existence of dopamine D1 and D2 receptor hetero-oligomers. The hetero-oligomer is characterized by distinct signaling and pharmacological properties. We have previously described the coupling of the complex to Gq, through which a novel PLC-coupled calcium signal is generated. This thesis explores functional consequences of this signal in neurons in vivo. Using D1 and D2 receptor agonists and antagonists, including the D1-D2 heteromer-specific agonist SKF 83959, to treat mice, we demonstrate that the calcium signal plays a role in the activation of striatal calcium/calmodulin kinase II (CaMKII), an enzyme important in synaptic plasticity. Modulation of CaMKII was specific to activation through the D1-D2 hetero-oligomeric population of dopamine receptors in mouse striatum. This same effect was also demonstrated in human embryonic kidney cells co-expressing D1 and D2 receptors, and provides some insight into the functional and physiological consequences of this signaling pathway.
Wiring the brain with Neto1: A multivalent NMDA receptor interacting CUB domain protein with essential roles in axon guidance, synaptic plasticity, and hippocampal-dependant spatial learning and memory

The defect in hippocampal synaptic plasticity in Neto1 tlz/tlz mutant mice suggested these mice might be impaired in hippocampal-dependant spatial learning and memory. Neto1tlz/tlz mutant mice were analyzed in the Morris water maze task and were found to have impaired spatial learning. The reduced LTP and the disruption of spatial learning in Neto1tlz/tlz mice are consistent with the decrease of NMDA-mediated currents, which can be explained by fewer receptors at hippocampal excitatory synapses. These findings highlight the important role of Neto1 in the regulation of synaptic NMDA receptors, and suggest it may play an important role in diseases affecting synaptic plasticity.Neto1 and Neto2 are homologous CUB (Clr, Cls/Uegf/Bmp1) domain proteins related to neuropilin and tolloid. Both Neto1 and Neto2 are expressed in the developing mouse embryo and the mature brain. To begin to understand the role of the Neto genes in the nervous system, Neto1 and Neto2 knockout mice were generated. While Neto1tlz/tlz and Neto2-/- mice are viable, fertile, and have no major morphological abnormalities of the brain, they show defects in axon projections and exhibit myoclonic-like seizures. These findings suggest that the Neto proteins are important for neural development and maintenance.Neto1 localizes to the postsynaptic density (PSD) of excitatory synapses and associates bivalently with N-methyl-D-aspartate (NMDA) receptors. One interaction between Neto1 and NMDA receptors is mediated by PSD-95, a major PSD scaffold protein, via the C-terminal PDZ tripeptide ligand of Neto1. Another interaction occurs independently of PSD-95, and is mediated by the first extracellular CUB domain of Neto1. Thus, Neto1 associates with NMDA receptors through intracellular and extracellular contacts. To determine whether NMDA receptor function is disrupted in Neto1tlz/tlz mice, long-term potentiation (LTP) was measured at Schaffer collateral-CA1 synapses in hippocampal slices. LTP and NMDA receptor-mediated currents were depressed at Neto1 tlz/tlz synapses. Furthermore, Neto1tlz/tlz mice have a specific reduction of NR2A-containing NMDA receptors at hippocampal synapses, but not in the overall expression level of these receptors in cells. These findings suggest that Neto1 plays a critical role in NMDA receptor-dependant synaptic plasticity, and in the delivery or stability of NR2A-containing NMDA receptors at these synapses.
Syntaxin-1A modulation of ATP-sensitive potassium channels: Implications on cardiac pathophysiology and beta-cell therapeutics

The current study examines the physiological importance of Syntaxin-1A (Syn-1A) regulation of ATP-sensitive potassium (KATP) channels. We found that Syn-1A reversed the effects of proton activation in cardiac KATP channels, exerted through an enhanced physical interaction between Syn-1A and the nucleotide binding folds (NBFs) of the channel in acidosis. As pH decreases prominently during early cardiac stress, Syn-1A may act as a physiological brake to limit K+ efflux and thus reduce the risk of arrhythmogenesis in these situations. In pancreatic beta-cells, cytoplasmic Syn-1A reduced the potency and efficacy of novel beta-cell-selective KATP channel opener (KCO) NNC 55-0462. The reduction of Syn-1A expression in diabetes may enhance the effectiveness of KCO therapy by increasing its efficacy and specificity. The ability of Syn-1A to modulate both cardiac and beta-cell KATP channels under different stimulus suggests that it regulates a common mechanistic pathway, possibly via interference with adenosine nucleotide activation on the NBFs.
A computational study on ethanol HCCI combustion

Homogeneous charge compression ignition (HCCI) engines have great potential in high efficiency with ultra-low NOx and particulates emissions. Therefore, fundamentals of HCCI and the control techniques of changing initial temperature, equivalence ratio, exhaust gas recirculation (EGR) rate and fuel reforming rate are examined using a single-zone well-stirred reactor model of an ethanol engine. In particular, the expansion of the Acceptable Operating Range (AOR) using fuel reforming, complemented by EGR, is investigated. It is found that reforming extends the complete combustion limit of the AOR, but shrinks the NOx emission limit. Reforming is also less effective than EGR in widening the AOR at the conditions studied. Therefore, reforming should be used only at temperatures near the ignition limit to enhance combustion. It is recommended that other control techniques, such as using different fuel and additives, and stratified charge combustion should be tested using a more sophisticated multi-zone well-stirred reactor model.