Showing papers by "Université de Sherbrooke published in 1970"

Cubic FeS, a Metastable Iron Sulfide

Abstract: Studies of the corrosion products of metallic iron formed in the absence of air oxidation in solutions of hydrogen sulfide have revealed the existence of a new phase, cubic FeS, associated with tetragonal iron sulfide, Fe1 + xS. This new phase is metastable and has a sphalerite-like structure.

Vérification expérimentale de l'épaisseur du film pour des liquides non‐newtoniens s'écoulant par gravité sur un plan incliné

Abstract: Leg epaisseurs des films liquides de douze solutions polymeriques s'ecoulant par gravite en regime laminaire, stable, sur un plan incline ont ete mesurees en fonction de plusieurs debits volumetriques du fluide. La valeur theorique de l'epaisseur du film a ete calculee en utilisant le modele rheologique d'Oswald-de Waele et en supposant aucun glissement apparent a la paroi. L'etude des resultats obtenus en comparant les valeurs experimentales et theoriques de l'epaisseur du film porte sur plus de 250 essais et montre en definitive que le modele d'Oswald-de Waele permet de predire l'epaisseur du film liquide avec une erreur relative moyenne inferieure a 4.0%. Cependant des calculs de l'epaisseur du film bases sur un comportement newtonient avec viscosite evaluee a la paroi demontrent clairement que l'epaisseur est peu influencee par la variation de la viscosite au travers du film liquide. Ainsi l'ecoulement par gravite sur un plan incline ne permet pas une verification rigoureuse du comportement rheologique des fluides non-Newtoniens.

Poverty and Inequality Impact Analysis Regarding Cotton Subsidies: A Mali-based CGE Micro-accounting Approach

Abstract: In this paper, we construct for Mali the first country-specific CGE model including a micro-simulation component so as to analyse how removing cotton subsidies in developed countries would impact poverty and inequality. To that effect, we have used the micro-accounting approach proposed by Chen and Ravallion. The issue has attracted significant attention, as it has played no small part in stalling the broader trade agenda. So far, research has been mainly carried out with a partial equilibrium analysis, whereas we use the first CGE micro-simulation model. A 17 sector CGE model comprising almost 5,000 households is used to demonstrate that removing cotton subsidies would contribute towards a significant decrease in poverty in Mali. Moreover, our results show that removing cotton subsidies while keeping other agricultural subsidies does not lessen the positive effects observed. It also appears that removing subsidies would marginally contribute towards easing inequality in Mali.

Sexual differences in the biogenesis of the androgens by the adrenal cortex in rat.

Abstract: Paired male and female rats of the same age were studied in terms of their in vitro adrenal incubation with 3H-pregnenolone. The labeled products were isolated and measured. It was found that, comparatively, the formation of corticosterone, androstenedione and dehydroepiandrosterone was higher in the female; testosterone was formed more in the male, while 11-betahydroxyandrostenedione production was variable. The ratio of each individual C-19 steroid to corticosterone was higher in the male, and the androstenedione: testosterone ratio was always higher in the female.

Experimental study of oblique circular cylindrical apertures in plates: Surpose of paper is to study systematically the effect of oblique penetration on stress concentration in steel plates

Abstract: Ten steel plates weakened by the penetration of an oblique circular cylindrical aperture have been tested. The generator of the aperture makes 0-, 15-, 30- and 45-deg angles with the normal to the plate surface. In the case of the first seven models, the tractions were applied in the direction normal and parallel to the plane of symmetry. The strain distributions around the aperture are presented in nondimensional forms along three generators 45 deg apart. The last three models, with large aperture diameter, were tested to investigate the effect of thickness-to-diameter ratio for the three angles of skewness. The experimental results are compared with the theoretical predictions. It is noted that, for most of the plates, there was a fairly good agreement for the stress distribution throughout the thickness. The results of the experiments for uniaxial state of stress have been superimposed in order to obtain the response for various biaxial conditions.

Pituitary-adrenal relationships in mice with hereditary nephrogenic diabetes insipidus, with special emphasis on the neurohypophysis and pars intermedia

Abstract: The extremely hypertrophic and hyperplastic pars intermedia (PI), of the hereditary nephrogenic diabetes insipidus (DI Os/+) mice, which is correlated to the increased neurosecretory activity of the hypothalamo-hypophysial system on one hand, and the hypertrophy of the adrenal cortex on the other, is compared to these structures in normal VII+/+ mice. In DI mouse, in addition to the moderate hypertrophy of the pituitary gland as a whole, other unique features include a great penetration of neurohypophysial fibres in PI and the presence of a great number of light glandular cells. Very often, these glandular cells are surrounded by neurosecretory fibres, pituicyte-like fibres or AF+ granules. The small marginal cuboidal cells bordering the hypophysial cleft contain and/or are surrounded by AF+ granules. These features are lacking in normal VII+/+ mice. The excess release of NSM from the neurohypophysis by different stresses such as dehydration, formalin injection, surgery and adrenalectomy is accompanied by a hypertrophy of PI and of the light glandular cells as well as of the adrenal cortex in the normal and DI mice. In DI mice under different conditions of stress, all the AF+ granules in different parts of PI disappear in addition to the above changes. From the present experimental evidence and from the fact that DI mice have a hypertrophied hypothalamus (neurohypophysis), pituitary and adrenal cortex, it appears that these three endocrine entities are functionally related. The role played by vasopressin in augmenting MSH, CRF and ACTH is discussed. The probable role of light glandular cells of PI in synthesis of ACTH or ACTH-like substances is also discussed.

Converter from delta modulation to pulse code modulation

Abstract: A system for the conversion of a delta modulation ( Delta M) signal into a pulse code modulation (PCM) signal and vice versa. The system for the conversion of a Delta M modulation signal into a PCM modulation signal comprises: register means for storing an input signal consisting of n binary digits generated by a Delta M modulator during a time period corresponding to a normal PCM modulation sampling period Ti, each binary digit representing a positive or negative Delta M modulation quantization step of a quantized signal; means for effecting the algebraic sum of the positive and negative quantization steps to obtain the increase or decrease of the quantized signal during the sampling period; means for multiplying the algebraic sum by a constant K representing the ratio of the value of a Delta M modulation quantization step over the value of a PCM modulation quantization step to obtain a binary signal representing the increase or decrease of the quantized signal in pulse code modulation quantization steps; and means for adding the binary signal obtained by the above multiplication to the binary signal obtained during the sampling period Ti 1 to obtain a binary output signal corresponding to the required pulse code modulation signal.

Effect of statolon on lactate dehydrogenase virus infection in mice.

Abstract: Statolon, an interferon inducer, was found to be effective in inhibiting the multiplication of the lactate dehydrogenase (LDH) virus in mice. Under the conditions tested, optimal protection was achieved by a single intraperitoneal injection (4.5 mg/20 to 22 g mouse) given 6 to 12 hours prior to the challenge. When various dilutions of the virus were compared, a relationship was observed between the original dose and the loss in titer at 24 hours. The results are interpreted as evidence supporting the view that interferon plays a role in the abrupt suppression of the initial high rate of LDH virus replication.

Variational Principle in Fluid Dynamics

Abstract: A variational principle is formulated for the flow of a viscous incompressible fluid taking into account the convective terms. The field of application of the variational principle is defined. A problem is solved for a time-dependent phenomenon when the fluid is a non-Newtonian pseudoplastic liquid obeying the power-law model due to its simplicity and to serve as an application of the variational principle.

Forum on teacher preparation: Comments of some problems of teacher education in mathematics

Abstract: Clearly, the mathematics that is relevant today is different from the mathematics that was relevant one hundred years ago. Yet, until quite recently, very little changes have occurred in mathematical curricula. So it is not surprising that some radical innovations are being tried out in different parts of the world. A number of these innovations have been instituted by university mathematicians; others, by secondary school teachers; and still others, by textbook publishers. In nearly every case the aim has been a short-term one. The very fact that secondary education has nearly always been singled out as the first target shows that quick results were expected, to produce university graduates with a greater understanding and a greater facility for the application of the newly-necessary mathematical concepts. This hurry to get things done has prevented most of the research from concentrating on the fundamental questions that arise in the building of a curriculum. It has also discouraged work in the elementary school. Now, it is being more and more realized that a more

Hybrid design method for dead-beat regulators†

Abstract: Since the works of Kalman (1963) and Tou (1964) it is known that an nth-order sampled-data system needs n control signals to reach equilibrium if taken in an arbitrary initial state. These control signals may be applied either in open loop, through linear feedback channels when all the state variables are accessible or with a digital compensator if only the output is available. A computational procedure for solving this problem is described. This method uses the analogue simulation of the process in order to form a linear system which is then solved on a digital computer giving directly the open-loop control signals. Then, with the open-loop control signals one sees how the feedback coefficients or the digital compensator can be found in a very simple way in order to get dead-beet response. The method has the advantage of keeping all the tedious work (matrix integration and matrix multiplication) to a minimum by using the analogue computer, the digital computer only having to solve two linear systems. The...

Gibbs free energy and activity coefficients from total pressure measurements

Abstract: Improvements of an existing method for the calculation of the Gibbs free energy and activity coefficients for binary non-ideal solutions from total pressure measurements are presented. These improvements are particularly significant whenever the ratio of the vapor pressures of the pure components is greater than 10. The convergence is rapid and the method is well adapted to digital computation. Ameliorations d'une methode pour le calcul de l'energie libre de Gibbs et les coefficients d'activite de solutions binaires non ideales a partir des mesures de pression total sont presentees. Ces ameliorations sont surtout importantes lorsque le rapport des pressions de vapeur des composants purs sont plus grand que 10. La convergence est rapide et la methode est tres bien adaptee au calcul digital.

Effect of Random Synchronization Errors in PN and PSK Systems

Abstract: The effect of a constant synchronization error on PN systems has been studied by Gill [1]. His results are generalized here for random synchronization errors, and extended to PSK systems using decision directed channel measurements [2]. In both cases, it is shown that the effect of random synchronization errors is to reduce the effective input signal power and to introduce an additional self-noise. The effect is minimized when the synchronization error has zero mean and can easily be evaluated in terms of circuit parameters.