McGill University Thèses et mémoires publiés en 1988

"The activity and kinetics of methanotrophs in a cultivated humisol were studied. The oxidation of methane demonstrated typical Michaelis-Menten kinetics with apparent Km values for CH 4 and o2 of 66.2 uM and 37.0 uM, respectively. Activity was significantly reduced at dissolved o2 ~ concentrations below 58 uM and completely inhibited at 9 uM. Competition for available oxygen and a high assimilatory demand for inorganic nitrogen by the methanotrophs inhibited the growth and activity of chemoautotrophic nitrifiers. Methane-dependent nitrite production was also demonstrated by the humisol. A bacterial consortium enriched from this sail consisted of a methane-utilizing component, a methylotroph …  Lire la suite

"De l'eau de fonte de neige et des solutions de sol de deux bassins forestiers ont été recueuillies au printemps 1986. L'étude de la variation temporelle de a• et de l'aluminium inorganique dissout dans ces solutions a démontré que l'eau de fonte acidifie la solution de sol. Cette acidification augmente la solubilité d'une phase solide d'aluminium et contribue ainsi à augmenter la concentration d'aluminium en solution. D'autre part, cette eau de fonte dilue le calcium dans la solution de sol. La dissolution de cette phase d'aluminium joue donc un rôle important dans le mécanisme de neutralisation de l'acidité par le …  Lire la suite

Vogel, Robert  Lire la suite

Side-chain ether groups in lignin model compounds of the general structure 1-(3$ sp prime$,4$ sp prime$-dimethoxyphenyl)-1,2-diaryloxyethane exhibited hydrolytic cleavage (the extent depending on the substituents on the 1-aryloxy groups) in aqueous 2N NaOH at 150$ sp circ$C (i.e. under wood pulping conditions). The level of hydrolysis increased in phenylpropane models (i.e. with $ gamma$-CH$ sb2$OH). Thus the commonly accepted generalization that 1,2-diethers of 3$ sp prime$,4$ sp prime$-dimethyoxyphenylpropane are stable in hot alkali is valid only for 1-alkoxy compounds. The newly observed hydrolytic cleavage is influenced by a combination of steric effects, electronic effects and solubility parameters. These observations now …  Lire la suite

Medium chain fatty acid oxidation was investigated in riboflavin deficient and 2-octynoic acid treated rats. Urinary metabolites of deuterium labelled fatty acid substrates were determined using gas chromatography-mass spectrometry. Control and experimental animals both produced labelled dicarboxylic acids. The ratio of chain length of dicarboxylates (C$ sb{ rm n+2}$/C$ sb{ rm c}$) was lowest in riboflavin deficient rats. As mitochondrial $ beta$-oxidation is inhibited, Peroxisomal $ beta$-oxidation appears to increase in response to inhibited mitochondrial oxidation in riboflavin deficiency. Administration of L-carnitine with the labelled substrates to half the rats showed that there were no differences in organic acid excretion …  Lire la suite

The purpose of the work contained in this thesis was to investigate whether experimental paradigms based on the system identification approach are an effective clinical assessment tool. This was accomplished by conducting two companion studies: a reliability study on a group of fifteen control subjects and a case study of an individual who had sustained a unilateral undisplaced ankle fracture. The data collected in both studies included ankle angular position, torque, and Tibialis Anterior and Triceps Surae electromyograms. From these data, measures of both static (e.g. range of motion) and dynamic (e.g. estimated elastic stiffness) joint function, were obtained. A …  Lire la suite

This thesis is concerned with the distributional problems related to quadratic forms in normal variables. Some functions of quadratic forms such as linear combinations and ratios will be considered. Our main focus will be on the investigation of ratios of quadratic forms. The moments, the density functions and the distribution functions will be derived analytically and presented in closed forms. Some cases where independence or commutativity hold will be studied extensively. Many new results are obtained and new derivations of known results are also proposed. Some particular cases as well as their applications are investigated. Some numerical examples are presented. …  Lire la suite

Cast Al-Si and Al-Si-Mg alloys containing up to 12.6 wt. pct. silicon and 1.0 wt. pct. magnesium were prepared. The changes in electrical conductivity/resistivity of these alloys due to strontium additions have been investigated and explained in terms of variations in microstructure. The conductivity behaviour of strontium-containing and strontium-free alloys was found to exhibit marked differences, depending on the silicon and magnesium contents and the rate of solidification. The electrical conductivity of single phase alloys containing less than 1.60 wt. pct. Si decreased with increasing silicon and magnesium levels. However, strontium had no effect on the conductivity of these solid …  Lire la suite

"This work was devoted to the study of {a) the effects of certain factors (nature of the organic acid solution , pH, and protein concentration) on the crystallization of the PhaseQ}us bean proteins, and (b) the physico-chemical and functional properties of the Ph~~Q!~~ bean proteins in relation to their microstructures. Alkali extracted (amorphous) and citric acid extracted (bipyramidal, spheroidal) proteins were prepared from !::_ vulg!!ri~ (white kidney, navy) and P. !~at~~ (baby lima, large lima) beans. The molecular weight distribution of the proteins in the extracts, supernatants, and the precipitates from each isolation procedure were determined by size exclusion HPLC. …  Lire la suite

The formalism of effective potential method is first studied for usual field theory and extended to supersymmetric field theory. The specific case of supersymmetric quantum electrodynamics is then introduced. The superfields are shifted as required by Weinberg's method for the evaluation of effective potentials and superpropagators are derived with the method developed by Helayel-Neto for cases where supersymmetry is explicitly broken. Then, the one and two loop corrections to the effective potential may be calculated. These corrections are seen to be complex everywhere but at the minimum of the potential. Tile theory is then renormalized in a modified minimal substraction …  Lire la suite

The immunological responses in hosts infected with Trypanosoma lewisi were examined during the course of infection and after recovery. Peak antibody levels coincided with the time of parasite elimination, but remained significantly elevated for over one year after the end of the infection The antigen repertoire recognized by antibodies demonstrated that some were revealed only by sera taken during the infection, and other antigens were revealed for the first time only by post-recovery sera. Immunomodulatory protective and suppressive factors were demonstrated in the plasma of irradiated, infected rats. These factors were identified as parasite-derived exoantigens which are shed in vivo …  Lire la suite

Anderson, Gary (Supervisor)  Lire la suite

Humoral immune function was studied in surgical patients. The antibody response to vaccination with a protein antigen, tetanus toxoid (TT), was reduced among all patients, especially those with reduced delayed type hypersensitivity (DTH) and increased degree of physiological derangement. The antibody response to a polysaccharide antigen, pneumococcal polysaccharide (PPS), was normal. In trauma patients, the antibody response to TT was normal. The in vitro production of specific and total immunoglobulin (Ig) by blood mononuclear cells was studied. Patients that failed to produce a serum antibody response to TT also failed to produce anti-TT in vitro. Anti-PPS production was normal. More …  Lire la suite

In this dissertation it is contended that central to Reinhold Niebuhr's theology and ethics is his understanding of the crucifixion of Jesus Christ as a revelation of the suffering of God. Keeping in mind the theologia crucis of Martin Luther, Part I examines the significance of the Christian symbol of the cross during Niebuhr's formative years and as he later sought to relate the moral and ethical insights of the Christian faith to the more tragic social and political events of his age. Part II begins with a systematic appraisal of Niebuhr's theology of the cross in reference to his …  Lire la suite

The immunobiology and the control of experimental visceral leishmaniasis were studied in susceptible (C57BL/6J) and resistant (C57L/J) strains of mice. It was found that the resistant/susceptibility phenotype for infection with L. donovani is expressed only by liver macrophage in vitro; the resistant/susceptible phenotypes were transfered reciprocally by bone marrow radiation chimeras. It was also found that the phagocytic activity of macrophages is reduced by the infection and that liver and peritoneal macrophages reflect their specific resistance/susceptibility phenotype following protective or curative treatment with lymphokines: macrophages from resistant C57L/J mice responded better to lymphokine activation. The production of IL-1 by spleen …  Lire la suite

This dissertation consists of three essays in international asset pricing. The first essay develops a model where investors face barriers to foreign portfolio investment. Using the standard mean-variance framework, risk return relationships for all securities are developed. It is also shown that: (1) previous models adopting this approach are special cases of this model, and (2) all investors generally prefer complete removal of barriers over other market structures. Essay #2 empirically explores the issue of the degree of segmentation of the international capital market for risky securities. Using the 'emerging market' (EM) data base, it is shown that the international …  Lire la suite