Showing papers by "University of Calgary published in 1987"

Arithmetic coding for data compression

Abstract: The state of the art in data compression is arithmetic coding, not the better-known Huffman method. Arithmetic coding gives greater compression, is faster for adaptive models, and clearly separates the model from the channel encoding.

Interventive Interviewing: Part II. Reflexive Questioning as a Means to Enable Self‐Healing

Abstract: Reflexive questioning is an aspect of interventive interviewing oriented toward enabling clients or families to generate new patterns of cognition and behavior on their own. The therapist adopts a facilitative posture and deliberately asks those kinds of questions that are liable to open up new possibilities for self-healing. The mechanism for the resultant therapeutic change in clients is postulated to be reflexivity between levels of meaning within their own belief systems. By adopting this mode of enquiry and taking advantage of opportunities to ask a variety of reflexive questions, a therapist may be able to augment the clinical effectiveness of his or her interviews.

Teachers' personal knowledge: What counts as ‘personal’ in studies of the personal∗

Abstract: ∗A version of this paper was published in Ben‐Peretz, M., Bromme, R. and Halkes, R. (1986) Advances of Research on Teaching Thinking (Swets & Zeitlinger/Swets North America Inc., Lisse/Berwyn). The paper is reprinted here with the permission of Swets & Zeitlinger b.v.

Corticotropin releasing factor-like immunoreactivity in the rat brain as revealed by a modified cobalt-glucose oxidase-diaminobenzidine method.

Abstract: A cobalt-glucose-oxidase diaminobenzidine (Co-GOD) method, employing a specific antiserum against rat corticotropin releasing factor (CRF), was applied to determine immunohistochemically a widespread and detailed localization of corticotropin releasing factor-like immunoreactivity (CRFI) in the rat brain. Besides the CRFI cells in the paraventricular hypothalamic nucleus that project to the median eminence, CRFI cells were demonstrated in many brain regions, including the olfactory bulb, cerebral cortex, septal nuclei, hippocampus, amygdala, thalamic nuclei, medial hypothalamic nuclei, lateral hypothalamic area, perifornical area, central gray, cuneiform nucleus, inferior colliculus, raphe nuclei, mesencephalic reticular formation, laterodorsal tegmental nucleus, locus coeruleus, parabrachial nuclei, mesencephalic tract of the trigeminal nerve, pontine reticular formation, lateral superior olive, vestibular nuclei, prepositus hypoglossal nucleus, nucleus of the solitary tract, dorsal motor nucleus of the vagus, lateral reticular nucleus, nucleus of the spinal tract of the trigeminal nerve, external cuneate nucleus, inferior olive, and medullary reticular formation. CRFI-reacting neural processes were also detected in these same areas. In particular, the median eminence, lateral septum, bed nucleus of the stria terminalis, mesencephalic reticular formation, parabrachial nuclei, and nucleus of the solitary tract contained large numbers of CRFI fibres. The widespread localization of CRFI demonstrated in the present study strongly suggests that CRF, like many other neurohormones and peptides, may act as a neurotransmitter and/or neuromodulator in numerous extra-hypothalamic circuits, as well as participate in neuroendocrine regulation.

Finite element handbook

Abstract: Finite element handbook , Finite element handbook , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Interventive interviewing: Part I. Strategizing as a fourth guideline for the therapist.

Abstract: A clinical interview affords far more opportunities to act therapeutically than most therapists realize. Because so many of these opportunities remain outside the therapist's conscious awareness, it is useful to elaborate guidelines that orient his or her general activity in directions that are liable to be therapeutic. The Milan associates defined three such basic guidelines: hypothesizing, circularity, and neutrality. Hypothesizing is clear and easy to accept. The notions of circularity and neutrality have aroused considerable interest but are not as readily understood. These guidelines may be clarified and operationalized when reformulated as conceptual postures. This process is enhanced by differentiating a fourth guideline, strategizing, which entails the therapist's decision making, including decisions about how to employ these postures. This paper, the first in a series of three, explores these four interviewing guidelines. The other papers will appear in a subsequent issue. Part II will focus on reflexive questioning, a mode of inquiry oriented toward mobilizing the family's own healing capacity. Part III will provide a scheme for analyzing and choosing among four major types of questions: linear questions, circular questions, reflexive questions, and strategic questions.

Monitoring distributed systems

Abstract: The monitoring of distributed systems involves the collection, interpretation, and display of information concerning the interactions among concurrently executing processes. This information and its display can support the debugging, testing, performance evaluation, and dynamic documentation of distributed systems. General problems associated with monitoring are outlined in this paper, and the architecture of a general purpose, extensible, distributed monitoring system is presented. Three approaches to the display of process interactions are described: textual traces, animated graphical traces, and a combination of aspects of the textual and graphical approaches. The roles that each of these approaches fulfill in monitoring and debugging distributed systems are identified and compared. Monitoring tools for collecting communication statistics, detecting deadlock, controlling the non-deterministic execution of distributed systems, and for using protocol specifications in monitoring are also described.Our discussion is based on experience in the development and use of a monitoring system within a distributed programming environment called Jade. Jade was developed within the Computer Science Department of the University of Calgary and is now being used to support teaching and research at a number of university and research organizations.

Mapping the boundaries of distance education: Problems in defining the field

Abstract: (1987). Mapping the boundaries of distance education: Problems in defining the field. American Journal of Distance Education: Vol. 1, No. 1, pp. 7-13.

Relationship between EMG patterns and kinematic properties for flexion movements at the human wrist

Abstract: EMG patterns associated with voluntary wrist flexion movements were studied in normal human subjects. Initially, subjects were trained to produce movements within five specified velocity ranges while the amplitude of the movement and the opposing load remained constant. In a second set of experiments, subjects were required to produce movements at four different amplitudes, moving as rapidly as possible against a constant load. Finally, with movement velocity and amplitude kept constant, the external load was varied so that different forces were required to generate the movements. The slowest movements were associated with a prolonged burst of EMG activity from the agonist muscle with little or no antagonist activity. With increasing movement velocity, there was a gradual evolution to the characteristic "triphasic" pattern associated with rapid voluntary movements. As velocity of movement increased further, the amplitude and area of the EMG bursts increased while burst duration and interburst intervals decreased. Increases in movement amplitude were accomplished mainly by changing the timing of the EMG bursts; with larger amplitude movements the antagonist burst occurred later. With movements against larger loads there was an increase in the size of the agonist burst and a decrease in the antagonist burst, but no change in the relative timing of the EMG bursts. These systematic changes in EMG patterns associated with different types of movement provide an indirect method of obtaining information concerning the motor programs which generate the movements.

Biomechanical aspects of playing surfaces

Abstract: The purpose of this paper is to discuss some biomechanical aspects of playing surfaces with special focus on (a) surface induced injuries, (b) methodologies used to assess surfaces and (c) findings from various sports. The paper concentrates primarily on questions related to load on the athlete's body. Data from epidemiological studies suggest strongly that the surface is an important factor in the aetiology of injuries. Injury frequencies are reported to be significantly different for different surfaces in several sports. The methodologies used to assess surfaces with respect to load or performance include material tests and tests using experimental subjects. There is only little correlation between the results of these two approaches. Material tests used in many standardized test procedures are not validated which suggests that one should exercise restraint in the interpretation of these results. Point elastic surfaces are widely studied while area elastic surfaces have received little attentio...

Analysis of a two-echelon inventory control system with complete redistribution

Abstract: This paper examines a two-level distribution system consisting of a central warehouse CW supplying several branch warehouses BW's, which, in turn, supply normally-distributed customer demands in a periodic-review environment. The CW replenishes system inventory using a base-stock replenishment policy and a predetermined order cycle of H time periods; i.e., every H periods, the CW orders enough from an outside supplier to bring the systemwide inventory position to a certain level to be determined based on a given minimum level of customer service. Upon receipt of this order, the CW allocates it entirely to the BW's so as to minimize the expected total units short at the BW's. This simple allocation scheme, may, of course, lead to out-of-balance BW inventories towards the end of the CW's order cycle. Hence, redistribution during the cycle should be considered. The redistribution treated here is a complete redistribution of all BW inventories one period before the end of the order cycle. Approximate formulas are derived which allow for a comparison of the system-wide inventories appropriate to each of two allocation schemes: 1 the simple allocation scheme only; and 2 the simple allocation scheme with total redistribution one period before the end of the order cycle. Limited computational tests indicate the magnitude of the improvements possible with total redistribution, and the sensitivities of these improvements to model parameters.

Phonocardiogram signal analysis: a review.

Abstract: Many disease of the heart cause changes in heart sounds and additional murmurs before other signs and symptoms appear. Hence, heart sound analysis by auscultation is the primary test conducted by physicians to assess the condition of the heart. Yet, heart sound analysis by auscultation as well as analysis of the phonocardiogram (PCG) signal have not gained widespread acceptance. This is due mainly to many controversies regarding the genesis of the sounds and the lack of quantitative techniques for reliable analysis of the signal features. The heart sound signal has much more information than can be assessed by the human ear or by visual inspection of the signal tracings on paper as currently practiced. Here, we review the nature of the heart sound signal and the various signal-processing techniques that have been applied to PCG analysis. Some new research directions are also outlined.

Retinal pigmented epithelial cells induced to transdifferentiate to neurons by laminin.

Abstract: Although the regeneration of nervous tissue in the vertebrate is very limited, there are a few remarkable examples of this process. Understanding the factors that regulate CNS regeneration in those areas of the nervous system where it occurs, will doubtless provide generally applicable, essential information about the process. It has been known for some time that the amphibian retina regenerates following its destruction. Transplant studies, confirmed later by in vitro experiments, have shown that one source of new neurons in regenerating retina is the retinal pigmented epithelium (RPE). RPE cells can transdifferentiate to either neurons or lens cells in culture, but little is known about the factors that regulate this process. A recent study in vivo of retinal regeneration provided evidence that the association of RPE cells with the retinal vascular membrane is an important step in transdifferentiation. We report here that transdifferentiation in vitro is profoundly influenced by the substrate on which the cells are cultured; RPE cells plated on laminin-containing substrates frequently transdifferentiate into neurons. In addition, we have found a high concentration of laminin in the Rana retinal vascular membrane. Therefore, we propose that retinal regeneration is initiated by changes in the composition of the extracellular matrix that RPE cells contact early in the process.

Specific labelling by peanut agglutinin of the outer acrosomal membrane of the human spermatozoon

Abstract: Experiments to bind fluorescein-conjugated Arachis hypogea (peanut) agglutinin (FITC-PNA) to washed human spermatozoa demonstrated that this lectin binds to the acrosome region in air-dried preparations. Since there was no binding when labelling was performed in suspension, and comparable labelling to that seen in air-dried preparations was seen when spermatozoa treated with saponin (to lyse the plasma membrane) were labelled in suspension, the lectin must bind to an intracellular structure, probably the outer acrosomal membrane. This was confirmed by ultrastructural localization of colloidal gold-conjugated lectin in saponin-treated spermatozoa. Treatment of spermatozoa with the detergent Nonidet P-40 caused a marked change in the binding pattern: more spermatozoa showed binding in the equatorial segment of the acrosome with no binding in the anterior cap region. A comparable, less marked, change was seen when spermatozoa were incubated overnight under conditions known to support the capacitation and spontaneous acrosome reactions. Treatment with the calcium ionophore A23187 for 1 h to induce acrosome reactions artificially in uncapacitated spermatozoa resulted in the appearance of patchy acrosome fluorescence. From these experiments it is concluded that PNA binds specifically to the outer acrosomal membrane, and that FITC-PNA-labelling may be used to monitor the human sperm acrosome reaction.

Presynaptic action of neuropeptide Y in area CA1 of the rat hippocampal slice.

Abstract: 1. Neuropeptide tyrosine (neuropeptide Y, NPY), a recently isolated endogenous brain peptide, reduces the extracellular population spike evoked by stimulation of stratum radiatum in area CA1 of the in vitro rat hippocampal slice, without reducing the antidromically evoked population spike. To test the hypothesis that NPY acts presynaptically, intracellular recordings were made of pyramidal neurones of area CA1 in vitro. 2. Bath application of 10(-6) M-NPY causes a long-lasting (1-1.5 h), reversible reduction of the orthodromically evoked excitatory post-synaptic potential (e.p.s.p.) recorded intracellularly from CA1 pyramidal neurones. This effect on the e.p.s.p. was dependent upon the concentration of NPY. 3. The resting membrane potential, slope input resistance, and action potential threshold, amplitude and duration of the CA1 pyramidal neurones were not affected by NPY. 4. The responses of CA1 pyramidal neurones to ionophoretic pulses of glutamate, applied to the dendrites during synaptic blockade, was also unaffected by NPY. 5. The evidence supports the hypothesis that NPY acts presynaptically in the CA1 region of hippocampus to reduce excitatory input to the pyramidal neurones.

Beyond Independence in Distance Education: The Concept of Control

Abstract: (1987). Concepts: Beyond independence in distance education: The concept of control. American Journal of Distance Education: Vol. 1, No. 3, pp. 3-15.

Winter respiratory activity in aspen woodland forest floor litter and soils

Abstract: Winter respiratory activity of aspen woodland litter layers and of the underlying Ah horizon from a southwestern Alberta site was examined, both under field conditions and over a matrix of defined lab conditions ranging from −6 to +18°C and from 0 to 300% water content by weight. Under freeze-thaw field conditions pronounced diurnal fluctuations in rates of CO2 evolution were apparent, from 100 to over 300mg CO2 m−2 h−1, whereas under snowpack, with isothermal conditions, rates remained near 150 mg CO2 m−2 h−1 At optimal moisture content (near 270%) rates of CO2 evolution ranged from 5 to 500 mg CO2 g−1 h−1, respectively, at temperatures from −6 to + 18°C, with marked respiratory declines evident at lower litter moisture contents. Predicted cumulative soil CO2 release during the winter period was estimated at 407–457 g CO2 m−2, depending upon whether the effects of post-thaw respiratory bursts were included, with over 75% of this activity occurring between 0 and −5°C. Thus, although over 60 freeze-thaw cycles were observed at the litter surface during the December to March period, most of the microbial activity occurred either at depths below the thaw line or during periods when the entire soil profile was frozen but protected from extreme low temperatures by surface snow cover. The magnitude of winter respiratory CO2 evolution, predicted from the modeling of lab respiratory rates on measured litter microclimate, was equivalent to nearly 60% of annual biomass input, a value that was in close agreement with mass loss data from earlier litterbag studies at the aspen site.