Showing papers by "University of Ottawa published in 1980"

Ethnicity, Contact and Communicative Competence in a Second Language

Abstract: A theoretical framework is presented which traces and relates the individual's acquisition, practice and maintenance of communicative competence in a second language to the social/structural characteristics of a community. These characteristics are mediated by a two-stage motivation process hypothesised to impact on fluency in a second language. Such competence will in turn, depending on structural aspects of the milieu, bring about integration or assimilation as social consequences. The implications of this formulation for future research are discussed and specific hypotheses outlined.

The scope of metastable peak observations

Abstract: This short review focuses attention upon the present status of metastable ion studies with emphasis upon the relationship between metastable peak shapes, ion structur and fragmentation mechanisms. Some recommendations are made concerning nomenclature and the reporting of observations on Gaussian-type metastable peaks. Experimental methods for recording relative abundances of metastable peaks are critically appraised. The relationship between metastable ion phenomena and isomerization of gaseous ions is reviewed with particular attention drawn to the effect of rate-determining isomerizations. The shapes of Gaussian-type metastable peaks are discussed in some detail and selected examples from recent studies are used to show that such peaks may, by appropriate experiments, be separated into two Gaussian-type components thus revealing new features of the fragmentation reaction. The magnitude and significance of released kinetic energies, T, are considered and it is stated that few conclusions can be drawn from the evaluation of T alone; the importance of accurate thermochemical data as an aid to understanding and interpreting kinetic energy release data is emphasized. Other topics discussed include composite metastable peaks, metastable peaks produced in chemical ionization and field ionization and the partitioning of internal energy of the fragmenting ion into translational degrees of freedom of the products, for reactions with and without a reverse energy barrier.

Design Considerations in Microstrip Antenna Fabrication

Abstract: Deviations in effective electrical dimensions caused by slight variations in finished microstrip antenna length, variations in the relative permittivity of the substrate material or nonuniformity in the substrate thickness lead to discrepancies between the designed and actual resonant frequencies. This sort of discrepancy is especially significant because of the narrow bandwidth of such antennas. It is found that for low dielectric substrate microstrip antennas, the critical parameter affecting the change in resonant frequency is the error in antenna length while for high permittivity substrates, the tolerance in dielectric constant is the critical parameter.

Analysis of a Microstrip Covered with a Lossy Dielectric

Abstract: The analysis of a microstrip line covered with a low-loss sheet material is presented in this paper. Numerical results show that the characteristics of a microstrip covered with a thick sheet of high dielectric constant are drastically affected. The effect is more for small values of W/h ratio. A closed-form expression for the dielectric loss of a multilayer structure is derived.The extension of present method to high-loss materials is also discussed. Numerical and experimental results for effective dielectric constant of a microstrip covered with low- and high-loss sheet materials are compared and found to be in good agreement.

Expected Energy Production Costs by the Method of Moments

Abstract: This paper outlines a new method of calculating the expected energy generation in a generating system by probabilistic simulation. The method of moments and a Gram Charlier expansion has been used in the new method. The proposed method can simulate the loading of units to equal marginal cost levels in an economic dispatch mode as well as the partial loadings caused by deratings. Multistate outage representations of generating units have also been accounted for and the results of selected examples portraying the above aspects have been given. Computationally, the proposed method is several times faster than existing simulation techniques.

Organization of the ascending striatal afferents in monkeys.

Abstract: Horseradish peroxidase was injected in various parts of the caudate nucleus and the putamen of monkeys to ascertain the relative locations of striatal projecting cells in the mesencephalon. The nigrostriatal component, as expected, is the greatest but numerous cells of the mesencephalic raphe system also project to the striatum. The projections from the pars compacta are organized in a topographical manner in all principal planes. The rostral two thirds of the substantia nigra are related to the head of the caudate nucleus. Nigral neurons projecting to the putamen are more posteriorly located and display an anteroposterior topography. The medial two thirds of the pars compacta send efferents to the head of the caudate nucleus from ventromedial to laterodorsal regions, reflecting a mediolateral topographical relationship. An inverse relationship exists dorsoventrally between nigra and caudate so that ventral compacta cells project to dorsal caudate and the dorsally situated neurons project to ventral-ventro-medial caudate regions. The dorsal and lateral parts of the putamen are more intimately related to the lateral and posterior nigra; by contrast, the ventral and ventromedial putamen receives more afferents from medial and central regions of the substantia nigra. A large group of cells in the tegmentum dorsal and medial to the medial lemniscus shows continuity with the pars compacta, and has similar connections with the striatum. This cell group should be included with the pars compacta. Significant overlap exists between the projection fields in all planes, making the nigrostriatal topographical organization seem less than precise. This apparent lack of point-to-point reciprocity may be due to the considerable size difference between the striatum and the substantia nigra. The raphe nuclei project to the greater part of the striatum but more significantly to its ventral and medial regions. The paranigral cell group sends its efferents mainly to the ventral striatum.

Decreasing self-stimulatory behavior with physical exercise in a group of autistic boys.

Abstract: Five autistic boys were observed during 27 language training sessions. Each session followed one of three periods: (a) physical exercise, (b) TV watching, or (c) regular academic work. It was found that (a) the lowest levels of self-stimulation followed physical exercise, (b) there were no differences in the levels of self-stimulation following TV watching and following academics, and (c) the levels of correct question answering were not affected by the three different previous periods.

The Component Structure of the Human Event-Related Potentials

Abstract: Publisher Summary This chapter discusses the component structure of the human event-related potentials (ERPs). Several years ago the world of human event-related potentials (ERPs) was a simple and comfortable place. There were evoked potentials related to sensation (N1), perception (P3), expectancy (CNV), and intention (BP). A variety of rather innocent theories held these components loosely together. Recently, however, there has been a proliferation of new components. The “exogenous” or stimulus-dependent components of the event-related potential can now be recorded from all levels of the afferent pathways. The “endogenous” components — those that can occur independently of external stimuli — have particularly multiplied. The late vertex potential following sensory stimuli consists of a series of waves — most prominently the N1-P2 components—that occur 50 and 250msec after a stimulus. This complex of waves is at first considered to be a non-specific response of frontal association cortex to incoming sensory information. Recent evidence has suggested that this response may consist of multiple subcomponent processes.

Survival and response to chemotherapy for advanced colorectal adenocarcinoma: an Eastern Cooperative Oncology Group report.

Abstract: A series of 1,314 cases of advanced measurable colon or rectal cancer were evaluated for objective tumor response and survival. All patients received chemotherapy according to protocols conducted by the Eastern Cooperative Oncology Group during the period between 1974 and 1977. For those patients who had not received chemotherapy prior to study entry, no therapy program under evaluations was significantly more active than the oral or intravenous 5-fluorouracil treatment programs with respect to survival or objective tumor response. The survival and response rates therapy programs under study, including methyl-CCNU, appeared to be comparable. Initial performance status (P < 0.001), weight loss in the six months prior to study entry (P < 0.001), and prior chemotherapy status were shown to be most prognostic for survival, and thus merit inclusion as stratification factors in any comparative trial involving this population. These factors were shown to have a cumulatively greater influence upon survival than the treatment program. Treatment differences were most accentuated within the favorable subgroups of the leading prognostic factors. The location of the primary tumor had a significant effect upon the eventual sites of metastatic disease involvement at the time of study entry (P < 0.001). The consequences of this analysis suggest that investigators need to address characteristics of the population under study. It is also noted that patients with chemotherapy prior to study entry are best suited for survival studies, while patients with no chemotherapy prior to study entry are well suited for both objective tumor response and survival studies.

The Purkinje neuron: I. A Golgi study of its development in the mouse and in culture.

Abstract: The development of the Purkinje neuron was studied in organotypic culture and compared to that occurring in the intact animal, using a modified Golgi-Cox method. The post-natal sequence of development in the intact animal occurred in five distinct stages beginning with (1) an immature state (0-3 days), (2) a stage of perisomatic dendritic processes (4-6 days), and then (3) a stage characterized by the presence of spines on the soma region (7-10 days). This stage of somatic spines has not been delineated previously in Golgi studies of the Purkinje cell during its development. There was no evidence that the lateral somatic processes resorb; rather they continue to grow and develop into dendritic branches. It is proposed that by a process of perikaryal translocation, the soma region becomes transferred "downward," resulting in an elongation of the primary, apical dendrite (stage 4, 11-14 days). Beyond 15 days (stage 5) the dendritic branches grow to the pial surface and the neuron has its full complement of secondary, tertiary, and spiny branches. In culture, the development parallels that occurring in the intact animal during the first 10 days (stages 1, 2, 3) despite the absence of extracerebellar afferents and the special conditions of the culture. However, there is an overall absence of lamination of the cortex, the Purkinje neurons do not align, and the developmental process is modified because of the failure of the process of perikaryal translocation in culture. The resultant mature neuron has an altered morphology characterized by the presence of several dendrites and spines attached to the soma, and also lacks the complete development of the smaller dendritic branches.

Characterization of gluconeogenesis in hepatocytes isolated from the American eel, Anguilla rostrata LeSueur,

Abstract: Isolated hepatocyte preparations from fed immature American eels,Anguilla rostrata Le Sueur, were used to study gluconeogenic, lipogenic, glycogenic and oxidative rates of radioactively labelled lactate, glycerol, alanine and aspartate. Eel hepatocytes maintain membrane integrity and energy charge during a 2 h incubation period and are considered a viable preparation for studying fish liver metabolism.

Effects of nocturnal gamma-hydroxybutyrate on sleep/waking patterns in narcolepsy-cataplexy.

Abstract: Continuous 48-hour polygraphic recordings of sleep/waking patterns were performed on 14 patients with narcolepsy-cataplexy before and after 7-10 days of treatment of their nocturnal sleep with gamma-hydroxybutyrate (GBH). GBH improved the quality of night sleep by increasing the amount of slow wave sleep, reducing stage I, increasing sleep efficiency (percentage of time in bed spent asleep), and reducing the number of periods of short sleep under 15 minutes. Also nighttime REM sleep was reduced in latency and became less fragmented. The daytime period contained less slow wave sleep and REM sleep, and fewer episodes of prolonged sleep. Patients experienced reduction or loss of daytime attacks of irresistible sleep, cataplectic attacks, and other auxiliary symptoms. Residual daytime drowsiness subsequently improved on low doses of methylphenidate. Tolerance did not develop and there were no serious toxic side-effects. Four of the patients had been refractory to previous combinations of antidepressants and high doses of stimulants.

A theory of capillary rise of a liquid in a vertical cylindrical tube and in a parallel-plate channel

Abstract: The classic equation of Washburn and Rideal for the rate of displacement due to surface tension forces of air by a liquid in a vertical capillary tube is based on the steady-flow parabolic velocity profile of Poiseuille across a section of the capillary. However, such a model of incompressible liquid flow cannot apply at the two ends of the liquid column in the capillary. The departure from Poiseuille flow in the vicinity of the advancing meniscus in a vertical cylindrical capillary is examined under the following assumptions. (i) The meniscus retains a fixed shape, which is the sector of a sphere making an angle of contact α with the capillary wall. (ii) The liquid has risen up the tube to reach a sufficiently slow quasi-steady flow, when both the acceleration and nonlinear inertia terms may be ignored. (iii) The usual nonslip flow condition is assumed at the tube wall except in the immediate region of the three-phase contact line, where the slip velocity is proportional to the shear stress exerted on the solid tube. The two regions are matched by the method of “inner” and “outer” expansions. (iv) At the meniscus, the tangential shear stress is zero and continuity of normal stress is approximated by assuming a fixed spherical shape. A generalization of Washburn's formula for the rate of rise of the meniscus as a function of height in a cylindrical tube is obtained. The meniscus exerts an extra drag which increases the effective height by an amount that increases with decrease in contact angle and the dimensionless ratio (slip coefficient/tube radius). A similar treatment of the flow near the meniscus moving up a parallel-plate channel is presented and a corresponding increase in drag due to the meniscus is obtained.

Rare earth element geochemistry of the Scourian complex N.W. Scotland — Evidence for the granite-granulite link

Abstract: Medium-to high-pressure granulite facies complexes represent samples of lower crustal material and are, therefore, important in the study of crustal processes. New rare earth element data for the Scourian granulite facies terrain of the Precambrian Lewisian complex of N.W. Scotland indicate that: These new data, along with previously reported major and trace element data, isotopic abundances, and trace element modelling support the hypothesis that the Scourian terrain is the residuum left after genesis and removal of granitic melts.

Diabetogenic effects of chronic oral cadmium adminstration to neonatal rats.

Abstract: 1 Chronic exposure of neonatal rats to oral cadmium (Cd) (0.1 and 1.0 micrograms/g daily for 45 days) disturbed glucose homeostasis, as reflected by hyperglycaemia, reduced liver glycogen and enhanced gluconeogenic potential of hepatic tissue. 2 This Cd-exposure regimen also increased hepatic cyclic adenosine 3',5'-monophosphate (cyclic AMP) which was accompanied by enhancement of basal, adrenaline and glucagon-stimulated form(s) of adenylate cyclase. 3 In order to assess the responsiveness of pancreatic beta cells to glucose, islets isolated from control as well as Cd-exposed animals were incubated in vitro and their rate of insulin secretion determined. In the presence of glucose 0.5 mg/ml, there was no significant difference in the rate of insulin release. However, at higher glucose concentrations (1.5 and 3.0 mg/ml), the islets from Cd-exposed rats released significantly less insulin than those of control animals. 4 The results are discussed in relation to the possible mechanism of the diabetogenic effect of Cd.

Image Segmentation with Directed Trees

Abstract: This correspondence presents a simple algorithm to detect and label homogeneous areas in an image, using directed trees for region labeling. The scheme constructs directed trees with the image points as nodes, guided by an edge value computed at every point. These directed trees segment the image into disjoint regions. Because of a valley seeldng property of the tree construction procedure, the boundaries separating the resultant segments pass through the center of the edges. The algorithm thus performs wel1 with thick and wide edges of varying height, because no thresholding of the edge image is involved. The properties of the resultant segments are stated in terms of the edge image. The algorithm is shown to be simple, efficient, and effective for detecting homogeneous segments in the presence of noise. Results of application in the algorithm to segment a LANDSAT multispectral scene of an agricultural area are included.

Minor physical anomalies in childhood autism. Part I. Their relationship to pre- and perinatal complications.

Abstract: In a study of minor physical anomalies and pregnancy complications in autistic children, 45 probands and 52 of their siblings were investigated. While there was a significant association between autism on one hand and minor physical anomalies and pregnancy complications on the other, no such association was found between physical anomalies and pregnancy and birth complications. Further, autistic children with higher anomaly scores had lower IQs, more frequent hospitalizations, and a more normal family history compared to autistic children with lower physical anomaly scores.