VictorJuiz/thesis huggingface dataset:
Finite element and experimental studies of springback in sheet metal forming

The ultimate goal of the metal forming industry is to form components made of a specific material into a required shape without experiencing wrinkling, bifurcation and springback. Of the aforementioned difficulties, attention in this thesis is devoted to springback resulting from unloading following stretch forming. In spite of the exhaustive application of the process to form many engineering components, the design and selection of sheet materials and tooling geometry to minimize springback still rely on the elusive trial and error approach. It is thus the objective of this thesis to avoid the ad hoc approach by analyzing the process using the finite element method. Three aspects of the current problem are accordingly investigated. The first is concerned with the development of a finite element model of the stretch forming process accounting for material and geometric nonlinearities, and interface conditions using ANSYS software. The second aspect of the work is concerned with the springback experienced by the deformed sheet following the punch release stroke. In the third, attention was focused to the validation of the invite element models. Two alternative test rig designs were developed to test the axisymmetric and the plane strain models. However, in view of cost and time limitations, only the plane strain stretch forming rig was built to test the corresponding FE model. The technique was then applied to a case study concerning the stretch forming of a rear bulkhead for an aircraft. (Abstract shortened by UMI.)
An evaluation of neonatal dopamine-depletion in the rat as a model of attention-deficit hyperactivity disorder

The neonatally dopamine-depleted rat exhibits transient spontaneous hyperactivity, which is attenuated by the administration of stimulants. As such, this rat has been proposed as an animal model of Attention Deficit Hyperactivity Disorder. Rats were administered 6-hydroxydopamine (i.c.v.) on post-natal day 3, and tested for hyperactivity, and attention-deficits, using the 5-choice serial reaction time task. The dopamine-depleted group showed juvenile hyperactivity, and impaired choice-accuracy and response time on the 5-choice test. However, 5-choice task performance impairments occurred with a more general behavioural depression and learning deficit. In addition, treatment with amphetamine did not ameliorate these deficits. These results suggest that neonatal dopamine depletion does produce the symptoms of ADHD, however a more substrate specific lesion producing a subtler DA-dysfunction would provide a more accurate animal model of the disorder.
The influence of genetically variable CYP2A6 on tobacco dependence and smoking behaviour

Nicotine is the psychoactive substance responsible for tobacco dependence; smokers adjust their cigarette consumption to maintain central nicotine levels. In humans, 60-80% of nicotine is metabolized to cotinine by the genetically polymorphic enzyme CYP2A6, an enzyme that also bioactivates tobacco-specific procarcinogens. I postulated that individuals with impaired nicotine metabolism (carriers of CYP2A6 null alleles) would experience greater aversive effects due to higher nicotine levels, or would need to smoke fewer cigarettes. Specifically I hypothesized: (1) that there would be an under-representation of individuals carrying CYP2A6 null alleles in a tobacco-dependent population, and (2) that within dependent smokers those with deficient nicotine metabolism would smoke less. Individuals carrying CYP2A6 null alleles were less likely to become smokers as demonstrated by their decreased representation in a tobacco-dependent ($\pm$ alcohol n = 244) versus a non-dependent, but tried tobacco control (n = 184) group (12.3% versus 19.6%, P $<$ 0.04, OR = 1.74, C.I. 1.02-2.94). In addition, within the tobacco-dependent only group, those homozygous for wild-type active CYP2A6 alleles (n = 143) smoked significantly more cigarettes per day (23 vs. 19, P = 0.035) than heterozygous individuals (carriers of one null allele, n = 18). This study demonstrates that an individual with even a single CYP2A6 null allele (i.e. heterozygous) (1) has a decreased risk of becoming a dependent smoker, (2) smokes less if dependent, and (3) may be at lower risk for developing cancer due both to a decreased smoke exposure and a decreased CYP2A6-mediated bioactivation of tobacco smoke procarcinogens.
The validity and reliability of a range of motion assessment of smile for children with facial palsy

Injury to the VII cranial nerve may result in a condition know as facial palsy, paralysis of the muscles of facial expression. For children with long-standing paralysis, re-animation surgery has provided them with the ability to smile. In order to assess the child's progress, the efficacy of therapeutic interventions and the long-term outcomes, it is important to establish a range of motion (ROM) assessment that is valid and reliable. The important attributes to measure in the ROM assessment of smile were identified and the content validity established. The inter-rater reliability of the clinically derived measures of smile was determined using three measurement tools: the modified hand held caliper (MCT), the ruler and the goniometer. The most clinically appropriate of the three tools was selected to complete each facial measurement. For clinical activities the MCT appeared to be reasonably consistent in the documentation of distance measurements in the assessment of smile. The ruler and goniometer were not found to be as reliable although the measurements of, lip droop and direction of smile are important in the assessment of smile. The results of this investigation have produced a ROM assessment that will reliably measure most of the gross motor components of smile deemed important in the clinical setting: commisure movement, upper lip movement, symmetry of the upper and lower lips and symmetry of the philtrum. To capture the smaller facial movements the community of researchers need to continue to perfect the computer analysis of facial movement.
Analysis and extension of the renormalization group treatment of fluid turbulence

The Navier-Stokes equations driven by a random stirring force have been treated with the Renormalization Group (RNG) methods by Yakhot and Orszag and other authors to obtain theoretical predictions of various constants of turbulence without empirically adjusted parameters. The analysis contains many approximations, some of which may be justified when the ratio of the resolution cutoff wavenumber ([Lambda]c) to the wavenumber under consideration (k) is very large. However, when this ratio approaches one (local interactions) many of the approximations required by RNG are no longer valid. Various methods attempting to extend RNG to include the local interactions have failed to produce results that could be validated. These attempts have been outlined and discussed in the first part of this study. In part two of this work, further attempt is made to extend the RNG method to produce turbulence models valid near the cutoff, specifically an eddy viscosity as a function of the wavenumber ratio (k/[Lambda]c) with a cusp up behavior for k/[Lambda]c [right arrow] 1. General properties of the partial averaging operation have been presented and modified to allow different methods of averaging subgrid Fourier triads. Three methods of deriving an eddy viscosity function have been proposed. The results do not match the most likely form of eddy viscosity obtained in other studies. The validity of the temporal approximations made in the RNG are analyzed.
Direct and indirect effects of fatty acids on secretion of the antidiabetic hormone, glucagon-like peptide-1

Glucagon-like peptide-1 (GLP-1) is produced from the proglucagon molecule by tissue-specific post-translational processing within intestinal L cells. GLP-1 regulates fuel homeostasis through its ability to stimulate the glucose-dependent secretion of insulin and to inhibit the secretion of glucagon. Furthermore, GLP-1 is a potent inhibitor of gastric acid secretion and motility, is a central satiety factor, and augments insulin sensitivity in peripheral tissues. Therefore, GLP-1 holds great potential for the treatment of patients with diabetes. By fully understanding the mechanisms that govern the secretion of GLP-1, the therapeutic potential of this hormone may be realized through strategies designed to increase its endogenous levels. Given the biphasic response of GLP-1 secretion to fat ingestion, it was hypothesized that fat has both direct and indirect effects on the L cell. To demonstrate this, both ' in vivo' and 'in vitro' techniques were utilized in the rat model. Long-chain monounsaturated fatty acids directly stimulated GLP-1 secretion whereas shorter chain length- and saturated fatty acids were not stimulatory to secretion. An atypical isoform of protein kinase C, PKC-[zeta], and a fatty acid binding protein were hypothesized to be involved in fat-induced GLP-1 secretion and their presence within L cells was confirmed by immunohistochemistry. Moreover, diets rich in monounsaturated fatty acids have been reported to improve glycemic tolerance in patients with type 2 diabetes. These diets were demonstrated to benefit glycemic control through increased secretion of GLP-1. The glycemic improvement was shown to be specific to GLP-1, as the GLP-1 receptor antagonist, exendin(9-39), completely abolished the benefit induced by a monounsaturated fatty acid diet. Finally, the indirect mechanism governing fat-induced GLP-1 secretion was demonstrated to involve an interaction between the intestinal hormone glucose-dependent insulinotropic peptide and the vagus nerve, with the role for the vagus nerve being predominant. Therefore, secretion of the antidiabetic hormone, GLP-1, involves a complex array of luminal, neural and endocrine elements, with ingested fat stimulating GLP-1 secretion through both direct and indirect pathways. In the future, these regulatory mechanisms may be modulated to increase the secretion of GLP-1 as a therapeutic approach to the treatment of patients with type 2 diabetes.
The custom of the country, justice and the colonial state in eighteenth-century Newfoundland

This thesis examines governance in Newfoundland from 1699 to 1832. It explores the formation of a colonial state--from the rule of the fishing admirals to the establishment of representative government--and focuses primarily on the customary legal institutions that arose in Anglo-Irish fishing communities during the eighteenth century. Three topics are covered in detail: naval government in St. John's; surrogate courts in the outport districts; and patterns in the administration of law. The analysis places the use of punishment in the context of the social relations in the fishery, in particular the reliance of capital upon wage labour supplied by indentured servants. Eighteenth-century courts played an active role in disciplining servants and enforcing sectarian regulations. Challenging an historiography which views early Newfoundland as politically backward and legally anarchic, this thesis argues that an effective colonial state emerged to meet the needs of those in power. The royal navy was the engine of law and authority, supplying the necessary infrastructure for the island's judiciary. Naval governors relied principally on their junior officers, the justices of the peace, and the fish merchants, who became actively involved in government whenever propertied interests were threatened. While the structure of this system differed markedly from that found in most British colonies, its function remained basically the same: power and authority flowed through institutions designed to uphold the established social order. Defined in the thesis as a "naval state," this regime dominated Newfoundland for nearly a century. In the 1820s the emergence of a bourgeois public sphere spawned a political reform movement that undermined the legitimacy of the island's legal system. The case of eighteenth-century Newfoundland demonstrates the malleability of the common law tradition in the face of an environment that demanded significant adaptation to local conditions. Government was essentially reactive, limited by available resources, and shaped by individual initiative. The legal system comprised an amalgam of common law, statute law, prerogative writ, and local customs. The large gap that existed between imperial policy and colonial practice formed a distinguishing characteristic of governance prior to 1832.
Finding a place in the sun, young Black women negotiate their identities in oppositional spaces

This thesis is a journey into the fives of several women who participated in the Miss Trinidad and Tobago Canada Pageant. As young Black women, these women struggle to survive in Canada where Whiteness is normative. As a result of their race, class, and gender, they are positioned as not Canadian. In resistance, they seek to create a sense of belonging. There has been much theorizing about 'beauty' pageants and pageantry in all of its forms. Some of the existing materials have argued that pageants are a space where women are subjected to sexist objectification, as well, a space where women gain access to economic rewards. The subjects of this thesis participated in the Miss Trinidad and Tobago Canada Pageant (1997 and 1998), in an attempt to create a sense of belonging. This study focuses on the identity making processes of young Black women in Canada.
Sequential changes in synaptic structure following long-term potentiation in the rat dentate gyrus

Long-term potentiation (LTP) continues to be one of the most compelling models of learning and memory. While LTP has been shown to be associated with changes in synaptic morphology, the nature of these changes over the electrophysiological time course of the enhanced response, has not been determined. The current research involved a detailed electronmicroscopic examination of synaptic structure in the rat dentate gyrus at various time points following the induction of LTP. The total number of synapses per neuron, synaptic curvature, the proportion of perforated synapses, and the maximum length of synapses were examined. No overall change in the number of synapses per neuron was observed in the LTP tissue at any of the time intervals. At 24 h, however, the 'degree ' of LTP expressed was associated with the number of synapses per neuron. In the LTP animals, the proportion of irregular shaped synapses was increased at 1 h, concave shaped synapses were increased at 24 h (not apparent under pharmacological blockade), and no overall changes in shape were observed at 5 days. The proportion of perforated synapses was increased at 1 h but did not differ from controls at later time periods. The increase in perforated synapses at 1 h was particularly apparent in the proportion of concave perforated synapses and these concave perforated synapses were also more prevalent at 24 h and 5 days. Synapses were larger overall at 1 h and 5 days but not different at 24 h. These differences in length were particularly evident in concave shaped synapses which were longer at 1 h, shorter at 24 h (no change under pharmacological blockade), and longer at 5 days. Stimulated synapses appear to initially lengthen and become more perforated (1 h), then become more concave in shape and divide or form new smaller concave synapses (24 h). Finally, synapses appear to grow in length and a higher proportion of concave perforated synapses is maintained (5 days). These results describe a sequence of changes in synaptic morphology that accompany and may support the neural plasticity that underlies LTP in a structure that is associated with learning and memory.
Mechanisms of ischemia and reperfusion-induced cytoprotection in canine gracilis muscle

Ischemia and reperfusion are known for their deleterious effects. Recent evidence, however, indicates that they may also produce a beneficial consequence. The first recognized ischemia and reperfusion induced cytoprotection was described in the Ischemic Preconditioning phenomenon. This cytoprotective phenomenon is well documented as a local effect. Recently, we have encountered an ischemia and reperfusion induced cytoprotection which is a remote effect. When a canine gracilis muscle was subjected to ischemia and reperfusion, it protected the contralateral paired muscle against the same stimulus. The purpose of this study was to characterize this remote cytoprotective effect. In the first phase of this study we developed a sequential muscle ischemia model utilizing a pair of canine gracilis muscles. In this model, one randomly chosen gracilis muscle was subjected to 5 hours of ischemia followed by 48 hours of reperfusion. Then the contralateral paired muscle (second muscle) was subjected to the same ischemia and reperfusion protocol. Muscle necrosis was evaluated after each muscle had been reperfused for 48 hours. The cytoprotection was observed as a significant reduction of muscle necrosis in the second muscle. The second phase of this study was to determine the period in which cytoprotection occurred within the ischemia and reperfusion episode. Using the ATP and Lactate analysis of the muscle biopsies, we had been able to identify that the second muscles were protected during the ischemic interval. Finally, in the third phase of our study, we developed a sensitive and quantitative method for measuring the inducible form of heat shock protein 70 (HSP70i). Using this method, we discovered that HSP70i may be associated with the cytoprotection observed in the second muscles.
Decentralized control of systems using switching methods

In this thesis, the adaptive control of decentralized systems using switching control methods is studied. The motivation for studying this problem arises when the model of the system being controlled is highly uncertain, i.e., when uncertainty in the plant model is sufficiently large such that a fixed LTI controller or traditional adaptive controller is ineffective to use. In this case, it is assumed that a dictionary of calculated decentralized controllers has been obtained which has the property that at least one of the controllers always satisfactorily controls the plant; a switching controller is then found which sequentially applies a controller from this dictionary of controllers to control the actual plant. Two approaches are investigated in this thesis. The first approach requires that a set of plant models be given, and that the real plant model belongs to this set. The other approach only requires that a family of controllers to exist with the property that at least one of them satisfies the control objective for the problem when applied to the actual system. In determining a solution to this switching control problem, a study of digital controllers for decentralized systems is made. Such digital controllers can potentially improve the overall performance of a decentralized control system, when a LTI continuous controller is ineffective. Conditions under which a digital controller can improve the performance of a decentralized continuous-time system are discussed. Also, it is shown that using Generalized Sampled-Data Hold Functions (GSHF) instead of a simple zero-order hold, in the implementation of the digital controllers, can significantly improve the overall performance of the resultant closed-loop system. In particular, it is shown GSHF can potentially be used to modify the structure of the digraph of the resultant discrete-time plant, by removing certain interconnections in the equivalent discrete-time model, to form a hierarchical system model of the plant, and in this case a decentralized digital switching controller can immediately be implemented in the resultant system.
Sugars in space, N-glycosylation mutants of the erythrocyte anion exchanger

Scanning N-glycosylation mutagenesis was used to determine the topology of a polytopic membrane protein, the human erythrocyte anion exchanger 1 (AE1), using cell-free translation and transfected cells. N-glycosylation acceptor sites located near the middle of large EC loops were efficiently N-glycosylated, however no N-glycosylation occurred at sites located within sharply defined regions close to the adjacent TM segments. To be efficiently N-glycosylated, EC loops in polytopic membrane proteins must be larger than 25 residues in size, with acceptor sites located greater than 12 residues away from the preceding TM segment and greater than 14 residues away from the following TM segment. Application of this requirement allowed a significant refinement of the topology of AE1 including a more accurate mapping of the ends of TM segments. The strict distance dependence for N-glycosylation of loops suggests that TM segments in polytopic membrane proteins are held quite precisely within the translocation machinery during the N-glycosylation process. A novel 12 transmembrane segment model for AE1 was proposed, with a T-loop structure connecting TM segments 9 and 10. Mutations designed to disrupt the folding of T-loop suggest that this loop may be transiently exposed to the lumen of the endoplasmic reticulum during biosynthesis, but normally folds rapidly, precluding N-glycosylation. The results indicate that the folding of the carboxyl-terminal region of AE1 is more complex than originally proposed and that this region of the transporter may have a dynamic aspect. Calnexin is a lectin-like ER chaperone, considered a dissociable part of the translocon complex. The spatial requirements for calnexin interaction with AE1 were characterized. The results show that the interaction of calnexin with the polytopic membrane glycoprotein AE1 was dependent on the presence but not the location of the oligosaccharide. Furthermore, calnexin was associated with AE1 after its release from the translocation machinery. A lectin gel-shift assay was developed, which allowed an enhanced resolution of glycoproteins by SDS gel electrophoresis. The use of N-linked glycosylation has proven a valuable tool to study the topology of a membrane protein in a fine detail and the dynamics of early stages of protein folding in the membrane protein biosynthesis.
On sum coloring of graphs

The sum coloring problem asks to find a vertex coloring of a given graph ' G', using natural numbers, such that the total sum of the colors of vertices is minimized amongst all proper vertex colorings of 'G'. This minimum total sum is the chromatic sum of the graph, [Sigma](' G'), and a coloring which achieves this total sum is called an optimum coloring. There are some graphs for which the optimum coloring needs more colors than indicated by the chromatic number. The minimum number of colors needed in any optimum coloring of a graph is called the strength of the graph, which we denote by 's'('G'). Trivially [chi](' G') <= 's'('G'). In this thesis we present various results about the sum coloring problem. We prove the NP-completeness of finding the vertex strength for graphs with [Delta] = 6 and also give some logarithmic upper bounds for the vertex strength of graphs with small chromatic number. We also prove that the sum coloring problem is NP-complete for split graphs. Polynomial time algorithms are presented for the sum coloring of ' k'-split graphs, 'P'4-reducible graphs, chain bipartite graphs, and cobipartite graphs. We can extend the idea of sum coloring to edge coloring and define the edge chromatic sum and the edge strength of a graph similarly. We prove that the edge sum coloring and the edge strength problems are both NP-complete for cubic graphs. Also we give a polynomial time algorithm to solve the edge sum coloring problem on trees, and show that using the Monadic Second Order Logic we can solve this problem on partial 'k'-trees with bounded degree in linear time.