McGill University Thèses et mémoires publiés en 1981

The effect of post-training self-stimulation on associations formed during classical conditioning was studied. In the first three experiments, rats experienced tone-shock, tone-water and tone-light pairings, respectively. Control groups experienced the same situations except that the temporal relationship between the stimuli excluded the possibility of an association being formed. Following this training period, the experimental animals pressed a bar for electrical self-stimulation of the brain; control animals did not self-stimulate. Retention of the association between the training stimuli was evaluated by measuring conditioned suppression of drinking (experiments 1 and 3), or extinction of secondary reinforcement. The results showed that self-stimulation can …  Read more

Tangasaurid eosuchians are represented by hundreds of specimens from the Permo-Triassic strata of Madagascar and Africa. The confusion surrounding the identification and anatomy of these reptiles is resolved by comparative anatomy and relative measurements, and three genera, Thadeosaurus, Tangasaurus and Hovasaurus, are described. Extensive growth series present a unique opportunity to study differences in growth strategies in two closely related Permian genera, one that was terrestrial (Thadeosaurus) and the other aquatic (Hovasaurus). The vertebrae of Youngina have a derived character state that indicates close relationship with the tangasaurids. A new genus and species of eosuchian, Acerosodontosaurus piveteaui, has a specialized …  Read more

Numerous techniques for assessing average areal rainfall from raingage networks are discussed. However, weather radar gives an accurate depiction of the spatial distribution of rain but errors may occur in rain amount estimations. Radar can be 'calibrated' with raingages and data used for rain monitoring, flash flood warnings, urban hydrology and hydrological procedures analysis. Studies have been conducted to test the accuracy of rain amounts forecasted over the City of Montreal a few hours ahead, using radar data to assess the impact of such forecasts on the City's wastewater control system. At coarse resolution (one rain depth value for each …  Read more

Rédiger un manuscrit en utilisant un programme d'ordinateur comme l'éditeur de texte représente un problème de difficulté inferieur dans lequel des schèmes appris antérieurement représentant le problème sont exécutés afin de construire le texte. Ce travail requiert suffisamment d'implication cognitive pour devenir une activité de résolution de problème. Ce travail reporte une étude longitudinale dans laquelle l'espace de problème de trois sujets est analyse à mesure qu'elles apprennent à se servir d'un éditeur de texte. La distinction entre le novice et l'expert est accentuée pour représenter une continuation du changement cognitif dans leur habileté avec un éditeur de texte. Les …  Read more

Although Bakunin's 1842 article, "The Reaction in Germany," published in the organ of the Dresden Left Hegelians, Deutsche Jahrbucher, is generally held to be the most radical and eloquent manifesto of Left Hegelianism, the standard historical commentary tends to consider his pre-1842 Russian works as far removed from this revolutionary ideal. Most historians have long failed to discern the logical continuity in Mikhail Bakunin's thought before and after the "pivotal" date of 1840. Indeed, his intellectual development is usually dividied into two distinct, mutually exclusive periods. During the first period, pre-1840, Bakunin is presented as a conservative and a monarchist, …  Read more

A novel technique of direct copper precipitation from a loaded chelating extractant using hydrogen in an autoclave (pressure hydrogen stripping) was studied. In its simplest form, the reaction is given by {CuL(,2)}(,org) + H(,2)(g) (--->) 2{HL}(,org) + Cu(s). Kelex 100 (Sherex Chemical Co. - commercial solvent extraction reagent), an alkylated derivative of 8-hydroxyquinoline was used as the basis of the present investigation and represents HL in the above equation. Two types of experiments were carried out: (a) those designed to study the chemical and thermal response of the extractant at high temperature and hydrogen pressures and (b) those which describe …  Read more

End-stage renal disease (ESRD) and its treatment are generally considered to be highly stressful and the associated loss of control over important life dimensions is believed to induce widespread depression. This situation was employed as a "living stress laboratory" in which to test the reformulated learned helplessness theory of depression. Results indicated that reduced perceived control over a variety of life dimensions was importantly related to increased depression, although the attributional reformulation of helplessness theory was not supported. Moreover, reanalyses of these data from a social learning theory perspective indicated that perceived self-efficacy contributed uniquely to this negative correlation in …  Read more

A review of the philosophical and psychological literature on free will is presented. Three major positions are identified: libertarianism, hard determinism and compatibilism (or soft determinism). The latter enjoys widespread and largely unchallenged support in psychology. Substantive conceptual and empirical grounds are presented which suggest that psychologists may be dismissing free will at their peril. It is argued, first of all, that belief in the reality of free will has profound implications for conceptions of human action, of moral responsibility, of the form and veracity of scientific accounts and of the validity of scientific reduction. Moreover, the results of a …  Read more

Factors affecting bovine ovarian responsiveness to stimulation by pregnant mare's serum gonadotropin (PMSG) were studied. Initially, the effects of plasma progesterone concentration on the response were considered using a progesterone-releasing intravaginal device (PRID) to provide an artificial source of the hormone. Due to inherent biological variation in vivo, in vitro methods were developed in which cAMP and progesterone production by granulosa cells were measured. Regardless of the size of the follicles from which the cells originated, PMSG stimulated significant cAMP accumulation. Cyclic AMP production was similar between aspirated granulosa cells and those scraped from the follicle wall, between ovaries with …  Read more

A simple method for purifying the gene A plus A* proteins of bacteriophage (PHI)X174 is presented. The purified preparation was able to stimulate (PHI)X DNA replication in vitro and was able to nick supercoiled (PHI)X RFI to produce unit-length linear and circular strands of DNA. The kinetics of the nicking reaction were more consistent with a stoichiometric than with a catalytic mechanism. Under non-denaturing conditions the presumably globular A and A* proteins sedimented with apparent molecular weights of 110,000 and 90,000 daltons. A* was unable to nick supercoiled (PHI)X RFI DNA in the absence of A, but participated in the …  Read more

In this thesis we consider linear multivariable frequency response systems with finite numbers of unstable poles but with no poles on the j(omega) - axis. We represent unstable systems by input-output mappings with restricted domains in (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) The effects of unstable perturbations in an open loop system K on the closed loop system (I + K)('-1) are studied. For this purpose the gap metric is introduced for measuring approximations to unstable systems. This metric is used to determine the sets of "allowable" uncertainties, i.e., those which do not destroy the stability of a feedback …  Read more

The thesis constitutes a systematic theoretical and experimental investigation into impulse breakdown voltage-time curves of coaxial-cylinder gaps in SF(,6) and a 50% SF(,6) - 50% N(,2) mixture. The breakdown time delay probability is treated as a bivariate distribution in statistical and formative time lags. A method is developed to deduce the marginal breakdown voltage probability curve from statistics of time delay. The experimental work was performed on 2.54/7.0-cm diameter, 60-cm long coaxial-cylinder electrodes using SF(,6) or SF(,6)-N(,2) mixtures at pressures of 0.1 - 0.3 MPa subjected to 0.5/50-(mu)s and 1.2/50-(mu)s impulses of both polarities. The effect of a spherical conducting …  Read more

A method was developed for measuring the rate of leaching of lignin macromolecules from the fibre walls of unbleached kraft pulp fibres suspended in water. From a comparison of a theoretical analysis with experimental results, it was concluded that the leaching process was governed by a diffusion mechanism. Very low and widely polydisperse diffusion coefficients were observed for this system. The molecular weights of the leached lignins were found to increase with wash time. A comparison of the molecular dimensions with pore size indicated that a flat disk-like conformation, rather than a spherical conformation was appropriate for the lignin macromolecule. …  Read more