Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1969. / Bibliography: leaves 255-257. / by William Woodruff Roberts, Jr. / Ph.D.

The purpose of this study was to compare the Karvonen and anaerobic threshold methods for prescribing the intensity component of physical activity exercise prescription in healthy adult males. A performance criterion was utilized to determine both the duration at which the subjects could maintain a physiological steady-state as well as their capacity for sustained exercise at the levels prescribed by the two methods. Subjects were males, ages 22-26 years with a mean VO₂max ±SD of 59.2 ± 5.6 ml•kg⁻¹•min⁻¹ and a predicted body fat of 14.1% ±2.5% (the latter estimated from regression formulas using skinfold measurements). Initially, subjects (N=10) performed graded exercise tests (GXT) to determine the exercise prescription. Each subject started at an initial load of 4 METS and thereafter increments were increased 0.33 METS every 20 seconds until volitional endpoints were reached. The variables measured during the GXT were oxygen uptake, ventilation, heart rate, blood pressure, respiratory exchange values and rating of perceived exertion (RPE). From the subjects' GXT, an exercise prescription was calculated by the Karvonen and anaerobic threshold prescription methods. Afterwards, a micro-computer was utilized to objectively and graphically display a predicted anaerobic threshold. Anaerobic threshold was accepted as the point at which minute ventilation became non-linear with respect to time. From the graded exercise test, anaerobic thresholds were determined in all subjects from the ventilatory responses. Mean anaerobic thresholds (±SD), when expressed as a percentage of the VO₂max were 65.3% ± 5.8%. The Karvonen method was also determined from the GXT data by multiplying a predetermined percentage (65-75% of the individual's cardiac reserve (cardiac reserve = HR_max - HR_rest). After the development of the exercise prescriptions, subjects were assigned to perform continuous exercise in two different training simulation trials. The order of assignment was randomized and administered in a double-blind fashion so that neither the researcher nor the subjects knew of the exercise prescription method being utilized. The subjects performed these trials on alternate days on a motor-driven treadmill for 60 min. To determine if a difference existed between the two exercise prescription methods, a series of dependent t-tests were performed on the following variables: duration of exercise at a prescribed level; the capacity to perform continuous exercise; oxygen uptake during the steady-state level; the rating of perceived exertion (RPE); and respiratory exchange values averaged for the entire simulation trials. The duration that the subjects performed at a prescribed level was significantly longer utilizing the AT method versus the Karvonen method (AT vs. KM, 29.0 vs. 16.4 min, respectively). However, there were no significant differences found in the subjects' oxygen consumption or rating of perceived exertion. When assessing the subjects' maximal capacity to perform continuous exercise during these two training simulation tasks, no significant differences (p ≥ .05) were found between the two training simulations. A statistical significant difference but small mean increase (p ≤ .05) was found in the peak heart rate (KM=l79 and AT=l74 bts·min⁻¹) attained during the training simulation tasks utilizing the two exercise prescription methods. Furthermore, a significant difference (p ≤ .05) occurred in the subjects' duration to exercise during continuous exercise. The subjects' exercised significantly longer utilizing the AT method. These findings reflected that the AT method was a more sensitive technique for allowing individual variability. In conclusion, the results of this study suggest that the anaerobic threshold method is a valid procedure to determine the exercise intensity for young, healthy adult males. / Master of Science

The amount of sulfoconjugates excreted by 135 free-living men and the effect of certain factors, i.e. familial cancer incidence, alcohol intake, tobacco smoking, marijuana smoking, medication and specifically analgesic use, exercise, protein intake and the number of meat and vegetable servings consumed daily, were investigated. One day of urine was analyzed for each subject and three days of urine were analyzed for a randomly selected sub-group of 40 subjects. For the one-day sample, the average amount of bound sulfate excreted was 7.45 mmole/24 hr. (0. 49 mole/mole creatinine). Total sulfate was 28.53 mmole/24 hr. (1.81 mole/mole creatinine). The values for the three-day sample were 7.65 mmole/24 hr. (0.49 mole/mole creatinine) and 28.92 mmole/24 hr (1.81 mole/mole creatinine) for bound sulfate and total sulfate, respectively. Of the environmental factors under consideration, a significant difference was observed only for sulfate excretion in relation to beer consumption. Beer consumers excreted more total sulfate in both one-day and three-day samples, and more bound sulfate in the three-day sample than non-beer consumers. Analysis of the three-day data revealed intra- (within subject) and inter-individual (between subject) coefficients of variation of 57.42% and 90.03% for bound sulfate (mmole/24 hr). For total sulfate, intra- and inter-individual coefficients of variation were 22.76% and 67.35%, respectively. The need to consider variation in experimental designs is discussed, and the necessity for further research regarding sulfoconjugate excretion and genetic and environmental influences is documented. / M.S.

Les systèmes de cultures intercalaires (SCI), qui combinent des plantes agricoles et des rangées d' arbres largement espacées les unes des autres, offrent de multiples bénéfices économiques et environnementaux, dans la mesure où les interactions arbre-culture sont bien maîtrisées. L'adoption à grande échelle de ces systèmes au Québec est cependant loin d'être acquise. Cette thèse visait à valider le potentiel des SCI pour le Québec, en accordant une attention particulière à la productivité de la culture intercalaire et des arbres, aux facteurs environnementaux qui la conditionnent et aux façons de l' optimiser. Les effets de différents clones de peupliers hybrides (PH) sur le rendement du soya ont été analysés. Un faible rendement du soya a été observé à l' interface PH-soya en situation de forte densité d' arbres et de concurrence pour la lumière. La floraison et la formation des gousses se sont avérées plus sensibles à l'ombrage des arbres que le remplissage des grains. Suite à une éclaircie des PH, le rendement du soya était toutefois plus régulier dans l' allée. Les résultats suggèrent que la concurrence pour la lumière peut être maîtrisée en optant pour des clones de PH qui minimisent l'ombrage et en favorisant de larges espacements des arbres sur les rangées et entre elles. Différents indices de qualité du sol ont aussi été évalués, dans un SCI avec soya et dans une plantation d'arbres sans culture intercalaire. À certaines dates, la disponibilité de l' azote et la biomasse microbienne étaient supérieures dans le traitement avec soya. On y a aussi observé un plus fort accroissement de la biomasse aérienne des PH, lesquels ont été plus efficaces à utiliser l' azote minéralisé. La qualité du sol à la base des PH, sous le paillis en polyéthylène, était inférieure à celle observée dans l' allée, contrairement à ce qui a été observé dans d'autres études portant sur des SCI sans paillis. Enfin, les effets de la culture intercalaire sur la croissance et le statut nutritif de différents clones de PH ont été quantifiés dans différents SCI. Globalement, la croissance des PH dans le traitement de culture intercalaire était supérieure à celle observée dans le traitement sans culture intercalaire. Les différents clones ont répondu de façon similaire aux traitements. L' azote s' est avéré limitant pour la croissance des PH. Les résultats suggèrent que les PH ont bénéficié de la régie des cultures intercalaires. En plus de démontrer le potentiel des SCI pour intensifier la production de bois en milieu agricole, cette étude indique que les premiers stades de l'association arbre-culture peuvent offrir une grande efficacité au plan de l' utilisation des ressources biophysiques.

Optimization techniques are used to investigate changes in structural design which increase the energy absorbing capabilities of a marine vessel in a collision. The structural model of the vessel includes the stiffened shell, web frame supports, and rigid bulkheads. The failure criterion used is hull rupture, appropriate for tanker design. The collision scenario is a right angle strike by a rigid vertical bow midway between two rigid bulkheads. The stiffened shell is modelled as a series of longitudinal beams in plastic bending and plastic membrane tension. Optimization parameters included both the number and dimensions of the transverse web frames and longitudinal beams. The technique was applied to the redesign of a large oil tanker. Minimizing the weight with a constraint on the energy was superior to maximizing the energy with a weight constraint in both computation time and performance. Optimization increased the volume of the shell beams while decreasing their moment-of-inertia. In addition the volume and strength of the frame were decreased precipitating early development of membrane tension in the shell and spreading of damage throughout the compartment. An reduced the number of web frames from optimum design six to two and increased the energy absorbed before rupture by 130%. Lesser collisions energies were found for more conservative designs which included a set number of web frames and restrictions of other design parameters. The use of high strength steel was also investigated. / M.S.

Tank track pads have been known to degrade rapidly under adverse conditions, especially during cross country service where the average life has been estimated to be 500 miles. Several factors have been identified as being the cause for such low service life. One of these is the 'quality of dispersion' which plays an important role in the performance of any rubber compound. In order to evaluate the effect of the quality of dispersion on the service life of rubber compounds, a controlled blending experiment was carried out with a recipe modeled on a standard track pad formula. Mechanisms of failure produced by a bad dispersion have been identified. Two interesting observations were made, one of which was the formation of voids and the other was crack propagation along flow lines which are directly relatable to processing conditions. / Master of Science

Cette étude présente des résultats zootechniques et économiques en lien avec une augmentation du poids d'abattage des porcs au Québec. Un essai zootechnique permet d'obtenir une appréciation de l'effet du poids d'ahattage sur les performances les plus susceptibles d'affecter la rentabilité d'une entreprise porcine. Dans cet essai, les outils de sélection que sont les indices de potentiel génétique ont permis de diminuer de façon substantielle l'impact d'une augmentation du poids sur la durée d'engraissement. Par ailleurs, une méthode d'analyse est présentée pour permettre la comparaison de courbes de performances pour différents ni veaux des facteurs à l'étude. Les performances de croissance peuvent maintenir un niveau élevé dans la zone des poids d'abattage considérés. Certains résultats présentés concernent l'évolution de la densité animale par parc durant l'engraissement, ainsi que la variabilité du besoin en lysine, et apportent un éclairage sur la problématique de l'augmentation du poids d'abattage. Finalement, des simulations effectuées au moyen de modèles économiques développés ont permis de mieux comprendre les interactions entre des variations du prix des aliments et du prix de vente des porcs, l'assurance stabilisation ainsi que le type d'entreprise, lors de la comparaison de la rentabilité obtenue à deux poids d'abattage. L'intégration de la stochasticité dans l'un des modèles permet de plus d'étudier l'impact d'une augmentation du poids sur le paiement de la vente des porcs.

This dissertation is a set of related papers on the application of the "principle of statistical adequacy" to single and multi-equation econometric models. The first chapter lays out the intended scope of the dissertation and defines the principle of statistical adequacy. The second chapter reviews the formulation of tests of statistical adequacy for multivariate models, and describes the implementation of these tests. The first approach that is discussed is to select particular functions of the variables involved that should be orthogonal under the null hypothesis of no misspecification, and the sample analog of these functions is used as a basis for constructing misspecification tests. As an extension of this idea, it is argued that viewing the model in explicit probabilistic terms provides a basis for developing a set of orthogonality conditions that can be tested in terms of all the probabilistic assumptions underlying the model. The formulation of misspecification tests via auxiliary regressions using general polynomial functions and the implementation of these tests via a menu-driven econometric modeling computer program is described. The third chapter reports the results of an empirical application of the principle of Statistical adequacy to the modeling of inflation/unemployment trade-offs for the U.S. Using a Statistically adequate “reduced-form" as the basis, a number of competing theoretical models are considered. The use of graphical techniques and formal misspecification tests in determining the adequacy of the statistical model are emphasized. It is found that none of the competing theoretical explanations of aggregate labor market behavior are acceptable in terms of the over-identifying restrictions imposed or their own statistical adequacy. The final chapter is an example of how one might proceed when a specification failures the criteria of statistical adequacy. For U.S. interest rates, it is shown that linear-homoskedastic autoregessions do not adequately account for the leptokurtosis and non-linear temporal dependence in the data. Using the evidence provided by preliminary data analysis as a guide, the Student’s t autoregressive model with dynamic heteroskedasticity is estimated for the log differences in three interest rate series. The estimation and misspecification testing results suggest that the STAR model adequately accounts for the probabilistic features of the data: bell-shape symmetry; leptokurtosis; first and second-order temporal dependence. In contrast, a number of other heteroskedastic specifications are estimated, and found to be statistically inadequate. / Ph. D.

The purpose of this research was to characterize the rhodium exchanged NaX and NaY zeolites as propylene hydroformylation catalysts. Catalytic activity was measured in a differential bed reactor. Flow in situ infrared spectroscopy was used to probe the coordination chemistry of the zeolite modified rhodium carbonyls. The catalytic activity of rhodium zeolites at atmospheric pressure and between 100-150ºC was measured. The rate of n-butyraldehyde production was approximately 5x10⁻³ moles/g-Rh hr at 150°C. Regioselectivity was dependent upon pretreatment. Precarbonylation with carbon monoxide, drying with air, and heating with N₂ prior to hydroformylation conditions produced a straight to branched isomer ratio (n/i) of 1.9-2.3. Partial reduction with 10% H₂ in N₂ at 127°C lowered n/i to 1.3. Hydrogenation to propane was 3-10 times faster than the hydroformylation rate at 150°C. Catalytic activity was sensitive to cation exchange conditions. Rhodium form, pH, temperature, and salt concentration altered catalyst behavior. Only RhCl₃•3H₂O preparations on NaY zeolite produced above 80ºC, a pH above 4, and a salt concentration of 0.1N NaCl were required in order to produce an active hydroformylation catalyst. Ammine complexes did not activate under any circumstances. It was found that the degree of hydration controlled the formation of rhodium carbonyls. On NaY, the hydrated rhodium zeolite reacted with CO at 120ºC to form Rh₆(CO)₁₆. By drying the zeolite in air at 190ºC, two rhodium dicarbonyls, Rh(CO)₂(O_z)₂-NaY and Rh(CO)₂(O_z)(H₂O)-NaY, were formed. The rhodium carbonyls were reacted with n-hexyl diphenylphosphine to determine rhodium locations. Rh(CO)₂(O_z)₂-NaY was located at the surface while the other two species were located within the zeolite cages. One dicarbonyl species, Rh(CO)₂(O_z)₂-NaX, was observed on NaX. It was determined by reactions with phosphines that this species resides in the zeolite cages. Reaction intermediates identified by FTIR under hydroformylation conditions suggested that the heterogeneous catalyst proceeds through a mechanism similar to that occurring in solution. Heterogeneous reaction orders also agreed with those reported for homogeneous hydroformylations. Addition of dimethylphenylphosphine (DMP) to the rhodium zeolites significantly increased regioselectivity. Rates were slightly less than those from the unmodified rhodium carbonyls. However, the phosphine modified rhodium zeolites deactivated within 16 hours. Continuous exposure to DMP decreased the rate of deactivation. / Ph. D.

Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2011-2012 / Dans ce mémoire, nous nous intéressons à la première version publiée de la pièce Littoral de Wajdi Mouawad en tant qu'elle se présente comme un acte de métacommunication. La pragmatique de la communication, de même que la narratologie, soutiennent notre étude du texte dramatique. Considérant d'abord les interactions complémentaires entre la génération aînée et celle de la jeunesse, nous remarquons que la crise existentielle vécue par cette dernière est tributaire d'un conflit intergénérationnel impossible à résoudre en raison de l'absence de métacommunication entre les interactants, ce qui entraîne une rupture de la relation. La jeunesse se voit alors privée d'une partie de son histoire et tente de se reconstruire. Notre analyse de la pièce porte ensuite sur les dialogues avec soi-même parce qu'ils contribuent à la résolution de la quête identitaire en incitant les jeunes à remettre en question leur existence passée et présente, et en ce sens, à métacommuniquer. Enfin, nous consacrons notre dernier chapitre aux interactions symétriques dans la pièce, particulièrement à la possibilité qu'elles offrent à la jeunesse de retisser le lien avec leurs origines, et donc, avec leur identité, par le biais de l'acte métacommunicationnel.