Showing papers by "Concordia University published in 1991"
TL;DR: It is found that the dopamine neurons of sensitized animals have become increasingly sensitive to excitatory pharmacological and environmental stimuli or desensitized to inhibitory regulation, and changes in cellular activity or protein synthesis may result in a change in the presynaptic regulation of axon terminal dopamine release.
2,042 citations
TL;DR: In this article, the ownership strategies of 128 retail franchising systems were examined in the light of existing agency and resource scarcity explanations of this organizational form, finding that franchiser ownership strategies are more heterogeneous than previously recognized, and that neither explanation alone accounts for observed ownership patterns.
Abstract: The ownership strategies of 128 retail franchising systems are examined in the light of existing agency and resource scarcity explanations of this organizational form. Findings suggest that franchiser ownership strategies are more heterogeneous than previously recognized, and that neither explanation, alone accounts for observed ownership patterns. A path model of franchiser ownership patterns embodying agency and resource scarcity elements is developed that is consistent with empirical findings.
438 citations
343 citations
TL;DR: In this article, a model for the prediction of the local frictional pressure drop of two-phase flows during vaporization of R-12 in capillary tubes is presented, with a relative error of about 15%.
320 citations
301 citations
TL;DR: The authors used Granger causality tests in investigating the relationship between exports and national income from a consistent data set for 47 developing countries in Africa and provided empirical results as well as suggestions for future research.
235 citations
TL;DR: Data suggest opiate receptors in or near the ventral tegmental area as sites of the opioid action that is responsible for opioid activation of the mesolimbic dopamine system.
Abstract: Microdialysis and high-performance liquid chromatography with electrochemical detection were used to determine extracellular levels of dopamine following ventral tegmental morphine injections into chloral hydrate-anesthetized rats. Morphine (13.2 nanomoles in 0.5 microliter of Ringer's solution) caused 50-150% increases in nucleus accumbens dopamine and metabolites; latency for the effect was on the order of 15 min with peak effects occurring in 30-50 min. Contralateral dopamine levels were influenced only minimally. These data suggest opiate receptors in or near the ventral tegmental area as sites of the opioid action that is responsible for opioid activation of the mesolimbic dopamine system.
216 citations
TL;DR: In this paper, a laboratory scale energy storage gypsum wallboard was produced by the direct incorporation of 21% to 22% commercial grade butyl stearate (BS) at the mixing stage of conventional Gypsum board production.
201 citations
TL;DR: In this article, the authors found that exercise and social contact both resulted in significant reductions in both the total and the psychological subscale of the Beck Depression Inventory (BDI), however, unlike the control conditions, resulted in decreased somatic symptoms of the BDI.
Abstract: Thirty community-dwelling, moderately depressed elderly were randomly assigned to 1 of 3 interventions: experimenter-accompanied exercise in the form of walking, a social contact control condition, and a wait-list control. Exercise and social contact both resulted in significant reductions in both the total and the psychological subscale of the Beck Depression Inventory (BDI). The exercise condition, however, unlike the control conditions, resulted in decreased somatic symptoms of the BDI. These results indicate that, at least in the short term, exercise has a broader effect compared with control conditions in reducing depressive symptoms in the moderately depressed elderly.
195 citations
TL;DR: In this paper, a closed-loop active current wave-shaping technique was proposed for input power factor correction, where nearly sinusoidal input currents are obtained at constant switching frequencies.
Abstract: A novel input power factor correction method that uses a closed-loop active current waveshaping technique is presented. The novel feature of the method is that nearly sinusoidal input currents are obtained at constant switching frequencies. Moreover, the method exhibits instantaneous current control, which results in very fast response and increased switch reliability. Selected predicted system performance and design methods were verified experimentally on a 1 kVA laboratory prototype. >
180 citations
TL;DR: A new method of recognizing handwritten Chinese characters using a structural representation called hierarchical attributed graph representation (HAGR) which can tolerate the variations of HAGR which reflect the instabilities or variabilities of handwrittenChinese characters resulting from different writing styles.
TL;DR: The reaction of the electrostatic cytochrome c-cytochrome oxidase complex with oxygen is measured by transient absorption spectroscopy and the role of CuA as initial electron acceptor in cy tochrome c oxidase is related to its physical proximity to cyto chrome c, which is the cyto Chrome c-Cytochrome oxidation complex.
TL;DR: In this paper, the authors argue that a careful consideration of possible constraints on organizational behavior and attitudes can facilitate both the production and consumption of organizational research, and the nature of such constraints is explored.
09 Apr 1991
TL;DR: By utilising the concept of integral manifolds, reduced-order models of the flexible system are obtained and this makes it possible to develop adaptive control schemes for the flexible full-order system at the reduced- order level, which otherwise would be difficult due to ill-conditioning and the curse of dimensionality.
Abstract: The problem of designing a robust adaptive control strategy for flexible joint robot manipulators is considered. By utilising the concept of integral manifolds, reduced-order models of the flexible system are obtained. This makes it possible to develop adaptive control schemes for the flexible full-order system at the reduced-order level, which otherwise would be difficult due to ill-conditioning and the curse of dimensionality. Two common adaptive control strategies are examined: (i) the adaptive inverse dynamics and (ii) the Slotine and Li algorithm. It is shown how these standard rigid adaptive control techniques can be generalized and improved for successful application to flexible joint manipulators. The result is robust adaptive control laws which take both parametric and dynamic uncertainties into account. Numerical simulations for a two-link flexible joint manipulator illustrate the potential and advantages of the new adaptive schemes as compare to the two standard algorithms in the literature. >
TL;DR: The results showed that the dendritic arbor of prefrontal cortical cells varied as a function of sex and neonatal gonadectomy, with females having less apical arbor than males in the cingulate areas, whereas, in the agranular insular cortex, females had greater apicalArbor than the males.
Abstract: Male and female Sprague-Dawley rats were given either gonadectomies or sham surgery on the day of birth. In adulthood they were sacrificed and prepared for Golgi-Cox staining. Using a camera lucida technique, layer II/III pyramidal neurons were drawn in the anterior cingulate cortex areas 1 and 3 and the agranular insular cortex and the number of dendritic branches on the apical and basilar dendrites were then summarized. The results showed that the dendritic arbor of prefrontal cortical cells varied as a function of sex and neonatal gonadectomy. In cingulate 3, castrated males had a smaller arbor on the left relative to normal males, whereas, in cingulate 1 the reverse was found. In addition, females had less apical arbor than males in the cingulate areas, whereas, in the agranular insular cortex, females had greater apical arbor than the males. Furthermore, in this region, gonadectomized groups had less arbor than their respective control groups. Finally, in the agranular insular cortex, the dendritic arbor was greater in the left hemisphere.
TL;DR: The objective of this study was to examine how plantar tactile (mechanical) events affect perceived plantar discomfort, and to evaluate the feasibility of a footwear safety standard, which requires elimination of the above illusion.
Abstract: Modern athletic footwear provides remarkable plantar comfort when walking, running, or jumping. However, when injurious plantar loads elicit negligible perceived plantar discomfort, a perceptual illusion is created whereby perceived impact is lower than actual impact, which results in inadequate impact-moderating behavior and consequent injury. The objective of this study was to examine how plantar tactile (mechanical) events affect perceived plantar discomfort. Also, we evaluated the feasibility of a footwear safety standard we propose, which requires elimination of the above illusion. Twenty subjects gave numerical estimates of plantar discomfort produced by simulated locomotion (concurrent vertical (0.1-0.7 kg.cm-2) and horizontal (0.1-0.9 kg.cm-2) plantar loads), with the foot supported by either a smooth rigid surface or a rigid surface with 2 mm high rigid irregularities. Vertical or horizontal load alone evoked no discomfort (P greater than 0.05), whereas together, discomfort emanated from loads as low as 0.4 kg.cm-2. Irregularities heightened discomfort by a factor of 1.89. This suggests that the proposed safety standard is feasible, since compliance could be achieved simply by adding surface irregularities to insoles and by other changes that heighten localized plantar loads. However, until this standard is adhered to, it might be more appropriate to classify athletic footwear as "safety hazards" rather than "protective devices".
TL;DR: In this article, the authors explore the possibility of using neural networks to identify faults that can occur in an AC-DC power system and compare three types of neural network models, which can sense AC bus voltages either as root mean square (RMS) values with or without phase angle information or as sampled instantaneous values of sine waves.
Abstract: The authors explore the possibility of using neural networks to identify faults that can occur in an AC-DC power system. Three types of neural network models have been studied and are compared. These networks can sense AC bus voltages either as root mean square (RMS) values (with or without phase angle information) or as sampled instantaneous values of sine waves. Depending on which method is used, some confusion can occur in distinguishing a line to line fault from a remote AC fault. A delay of 1-2 cycles in detection of faults when using RMS values is expected due to the algorithm required for determining the RMS value. This may not be too critical in practice. However, where this delay is unacceptable, instantaneous values may be used. Based on the ability of these networks to distinguish reliably between different types of faults, appropriate control measures can be taken to improve the dynamic performance of the AC-DC power system. >
TL;DR: The performance of a three-phase solid-state reactive power compensator with fast dynamic response is analyzed and a mathematical model for the compensator connected across a variable power factor load is derived.
Abstract: The performance of a three-phase solid-state reactive power compensator with fast dynamic response is analyzed. The compensator consists of a three-phase pulse-width modulated voltage-source inverter connected to a self-controlled DC bus. The principal advantage of this scheme is that it can maintain a near-unity source power factor without sensing and computation of the associated reactive power component. A mathematical model for the compensator connected across a variable power factor load is derived. The frequency response is obtained for open-loop operation. This allows the design of the controller. Predicted results are verified experimentally for both open and closed-loop responses. >
TL;DR: This work is intended to provide a non-mathematical introduction to the advantages and problems of LVPA for clinical researchers who are not yet familiar with this powerful procedure.
Abstract: Latent variable path analysis (LVPA) is undoubtedly one of "the" new statistical techniques being used increasingly often by clinical researchers. Although well suited for some types of clinical research, LVPA can be a somewhat intimidating technique for novices. This work is intended to provide a non-mathematical introduction to the advantages and problems of LVPA for clinical researchers who are not yet familiar with this powerful procedure. The conceptual bases of LVPA, its relation to other statistical techniques, and possible uses and misuses in clinical research are considered. Many practical recommendations for the appropriate use of LVPA also are offered, as is a suggested reading list for researchers who wish to learn more about LVPA and related approaches.
TL;DR: The Search for a Finite Projective Plane of Order 10 as discussed by the authors is a seminal work in the area of infinite projective planes of order. The American Mathematical Monthly: Vol. 98, No. 4, pp. 305-318.
Abstract: (1991). The Search for a Finite Projective Plane of Order 10. The American Mathematical Monthly: Vol. 98, No. 4, pp. 305-318.
TL;DR: In this article, the effect of pH, initial cresol concentration, and radiant power levels on the degradation of o-, m-, and p-cresol was examined in detail, showing that the resulting kinetic expression for the rate of degradation is a complicated function of various parameters and is silent as to the details of the initial photooxidative steps.
TL;DR: In this paper, a new approach based on the state space principle of modern control theory has been proposed to calculate thermal response factors of building envelopes without finding the roots of the roots.
TL;DR: In this article, the authors evaluated the superplastic ductility of an Al-lOMg-0.1Zr alloy at 300 °C and found that the super-plastic response can be enhanced by simultaneously increasing the total rolling strain, the reduction per pass, and the duration of reheating intervals between passes during isothermal rolling.
Abstract: Variations in thermomechanical processing (TMP) which regulate the microstructural characteristics and superplastic response of an Al-lOMg-0.1Zr alloy at 300 °C were evaluated. Mechanical property data revealed that the superplastic ductility can be enhanced by simultaneously increasing the total rolling strain, the reduction per pass, and the duration of reheating intervals between passes during isothermal rolling. Texture and microscopy data were consistent with the development of a refined microstructure by recovery-dominated processes, i.e., continuous recrystallization, during the processing. The mechanisms by which a refined substructure can be progressively converted into a fine-grained structure during repeated cycles of deformation and annealing are addressed. A qualitative description of the complex sequence of developments leading to a microstructure better suited to support superplastic response is presented.
TL;DR: In this article, a spectrum analysis technique is proposed to model the pulsating flows through openings of a building and the governing equations for fluctuating airflow behavior are obtained from the pressure/force balance between the turbulence pressure differences across openings and the forces required to overcome the flow resistance and inertia of air.
TL;DR: In this article, Granger's test is employed to examine the causal relationship between the size of the export sector and national income per capita (as well as their respective growth rates) for China for the period 1952-1985.
Abstract: In this paper Granger's test is employed to examine the causal relationship between the size of the export sector and national income per capita (as well as their respective growth rates) for China for the period 1952–1985. Our empirical results favour a bi-directional causal sequence between these two variables. However, these findings disappear when a similar test is used for the sub-period 1952–1978. The difference in results between these two sample periods points to a change in causal relation after 1978 which coincides with the adoption of an “outward looking” strategy by the Chinese government in that same year. [124]
TL;DR: The performance of a multicast switch, a space division switch in which a packet at an input port is routed to a subset of the output ports, is discussed and a Monte-Carlo simulation of the system is devised.
Abstract: The performance of a multicast switch, a space division switch in which a packet at an input port is routed to a subset of the output ports, is discussed. The delay under the assumption of input port buffering is determined. The system is modeled as an independent set of M/G/1 queues. A key assumption in the analysis is that output port contention is settled by random selection among the contending input ports. In order to justify this as well as the other assumptions, a Monte-Carlo simulation of the system is devised. Numerical results from the analysis and simulation of the system are presented. >
TL;DR: In this paper, a bisphenol A-based epoxy adhesive was modified by polyblending with Kraft Lignin (L) and the possibility of an enhanced degree of bonding between L and the epoxy network was discussed.
Abstract: A bisphenol A based epoxy adhesive (EP) was modified by polyblending with Kraft Lignin (L). A systematic investigation of the thermally cured EP-L polyblends with up to 40% by weight L was undertaken. Adhesive shear tests, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and solid-state CP-MAS NMR spectroscopy were performed to establish the effect of L on the mechanical properties of the polyblends and on the morphology of these crosslinked structures. The possibility of an enhanced degree of bonding between L and the EP network is discussed. This bonding can arise from a chemical reaction between L and some unreacted amine groups present in the hardener.
TL;DR: The present investigation suggests that, while the early housing manipulation produced a differential sensitivity in rats to the stimulant properties of cocaine, the same manipulation failed to alter the sensitivity of Rats to the reinforcing properties of Cocaine as assessed through self-administration.
Abstract: Several reports in the literature suggested that environmental influences which are reflected in the social housing conditions of the rat may play a role in the expression of individual differences in drug self-administration. The present experiments were performed in order to further examine the effects of early housing manipulations, as reflected by grouped or isolation housing, on cocaine-induced behavioral responding. The first study examined the effects of this manipulation on the locomotor stimulant properties of cocaine. The results suggested that grouped housing produced a significantly greater increase in cocaine-induced locomotion than was observed in animals housed in isolation. Experiment 2 examined the effects of housing manipulations on the self-administration of cocaine under a continuous reinforcement schedule. Differences in the rate of cocaine self-administration were only observed at the lowest dose tested. Responding at all other doses was equivalent, including the optimal dose for both groups, suggesting that the housing manipulations failed to affect the reinforcing efficacy of cocaine. The present investigation suggests that, while the early housing manipulation produced a differential sensitivity in rats to the stimulant properties of cocaine, the same manipulation failed to alter the sensitivity of rats to the reinforcing properties of cocaine as assessed through self-administration.
TL;DR: The authors found that dysphoric subjects were less successful suppressing negative and more successful suppressing positive thoughts than nondysphoric subjects when given either success or failure feedback on a test and asked not to think of this test while completing a 5-min think-aloud procedure.
Abstract: Two studies addressed dysphoric individuals' suppression of unwanted thoughts. The mood-congruence hypothesis was that dysphoric subjects would be less successful suppressing negative thoughts and more successful suppressing positive thoughts than nondysphoric subjects. The cognitive-effort hypothesis was that dysphoric relative to nondysphoric subjects would be less successful suppressing thoughts of any kind, particularly in the latter portion of a suppression period. In Study 1, dysphoric and nondysphoric subjects were given either success or failure feedback on a test. They were then asked not to think of this test while completing a 5-min think-aloud procedure. In line with the mood-congruence hypothesis, dysphoric subjects had more intrusions of failure and fewer intrusions of success than nondysphoric subjects. In line with the cognitive-effort hypothesis, dysphoric subjects in both feedback conditions exhibited more intrusions in the fifth, final minute of the think-aloud period. In Study 2, dysphoric and nondysphoric subjects were instructed not to think of the neutral target white bear. Again, dysphoric relative to nondysphoric subjects exhibited more intrusions in the fifth, final minute of the think-aloud period.
TL;DR: The notion that internal state language may be one way of regulating sibling interaction and also a potential means for siblings to construct shared meanings about their world is highlighted.
Abstract: This study examined relations among preschoolers' sibling-directed internal state language, perspective-taking abilities, and sibling-directed affective behaviors in 32 sibling dyads (aged 14 months and 3-4 years) during naturalistic home observations. Preschooler references about internal states (emotions, wants, abilities) were significantly more likely to be (a) about the toddler than the self, and (b) made in the mother's absence and during sibling conflict and play. Relative to poor perspective takers, skillful perspective takers (a) engaged in more instances of internal state discourse and (b) talked more frequently about both the toddler and themselves. Preschoolers engaging in high levels of positive affective behavior also spoke more frequently about internal states than children engaging in low levels of positive affective behavior. Discussion of results highlights the notion that internal state language may be one way of regulating sibling interaction and also a potential means for siblings to construct shared meanings about their world.