Showing papers by "University of Calgary published in 1990"

Stories of Experience and Narrative Inquiry

Abstract: Although narrative inquiry has a long intellectual history both in and out of education, it is increasingly used in studies of educational experience. One theory in educational research holds that humans are storytelling organisms who, individually and socially, lead storied lives. Thus, the study of narrative is the study of the ways humans experience the world. This general concept is refined into the view that education and educational research is the construction and reconstruction of personal and social stories; learners, teachers, and researchers are storytellers and characters in their own and other's stories. In this paper we briefly survey forms of narrative inquiry in educational studies and outline certain criteria, methods, and writing forms, which we describe in terms of beginning the story, living the story, and selecting stories to construct and reconstruct narrative plots. Certain risks, dangers, and abuses possible in narrative studies are discussed. We conclude by describing a two-part r...

Assessing proportionality in the proportional odds model for ordinal logistic regression.

Abstract: The proportional odds model for ordinal logistic regression provides a useful extension of the binary logistic model to situations where the response variable takes on values in a set of ordered categories. The model may be represented by a series of logistic regressions for dependent binary variables, with common regression parameters reflecting the proportional odds assumption. Key to the valid application of the model is the assessment of the proportionality assumption. An approach is described arising from comparisons of the separate (correlated) fits to the binary logistic models underlying the overall model. Based on asymptotic distributional results, formal goodness-of-fit measures are constructed to supplement informal comparisons of the different fits. A number of proposals, including application of bootstrap simulation, are discussed and illustrated with a data example.

Transition from maternal to embryonic control in early mammalian development: a comparison of several species.

Abstract: La presente revue considere les donnees recentes concernant les produits impliques dans l'activation du genome de l'embryon chez plusieurs especes

Child and parent effects in boys' conduct disorder: A reinterpretation.

Abstract: The importance of parent and child influences on the development of conduct disorder in boys is evaluated. The research approaches reviwed include studies of interactions between unrelated mothers and children, reaction to punishment, autonomic reactivity, biochemical factors, and drug treatment and longitudinal studies of delinquency.

Gastric ulceration induced by nonsteroidal anti-inflammatory drugs is a neutrophil-dependent process

Abstract: The hypothesis that neutrophils play an important role in the pathogenesis of gastric ulceration induced by nonsteroidal anti-inflammatory drugs (NSAIDs) was tested in rats. Rats made neutropenic by prior treatment with an antibody to rat neutrophils raised in goat were found to be significantly more resistant to the gastric-damaging actions of indomethacin or naproxen than were control rats or rats pretreated with normal goat serum. The reduction of damage in neutropenic rats was not due to effects of the antineutrophil serum on either gastric acid secretion or the ability of indomethacin or naproxen to inhibit prostaglandin synthesis. Gastric cyclooxygenase activity was inhibited by greater than 95% in both normal and neutropenic rats that received indomethacin or naproxen. Reduction of circulating neutrophil numbers by treating rats with methotrexate also resulted in a significant reduction in the susceptibility to gastric damage induced by indomethacin. Since activation of circulating neutrophils appeared to be important in the development of gastric erosions after administration of indomethacin, and in the significant changes in vascular endothelial integrity (Monastral Blue staining) observed within 15 min of indomethacin administration, we investigated the possibility that leukotrienes (LTs) and platelet-activating factor (PAF) might be involved in the pathogenesis of indomethacin-induced ulceration. Changes in gastric LTB4 synthesis were not observed after indomethacin administration. Pretreatment with either an LTD4 antagonist or a PAF antagonist was without significant effect on the extent of gastric damage induced by indomethacin. These results suggest an important role for neutrophils in the pathogenesis of NSAID-induced gastric ulceration. Neutrophils may be important in the vascular injury that occurs early after administration of these compounds.

Zebrin II: a polypeptide antigen expressed selectively by Purkinje cells reveals compartments in rat and fish cerebellum.

Abstract: Monoclonal antibody mab-zebrin II was generated against a crude homogenate of cerebellum and electrosensory lateral line lobe from the weakly electric fish Apteronotus leptorhynchus. On Western blots of fish cerebellar proteins, mab-zebrin II recognizes a single polypeptide antigen of apparent molecular weight 36 kD. Immunocytochemistry of apteronotid brains reveals that zebrin II immunoreactivity is confined exclusively to Purkinje cells in the corpus cerebelli, lateral valvula cerebelli, and the eminentia granularis anterior. Other Purkinje cells, in the medial valvula cerebelli and eminentia granularis posterior, are not zebrin II immunoreactive. Immunoreactive Purkinje cells are stained completely, including dendrites, axons, and somata. The antigen seems to be absent only from the nucleus. A similar distribution is seen in catfish, goldfish, and a mormyrid fish. Zebrin II immunoreactivity is also found in the rat cerebellum. Western blotting of rat cerebellar proteins reveals a single immunoreactive polypeptide, with apparent, molecular weight 36 kD, as in the fish. Also as in the fish, staining in the adult rat cerebellum is confined to a subset of Purkinje cells. Peroxidase reaction product is deposited throughout the immunoreactive Purkinje cells with the exception of the nucleus. No other cells in the cerebellum express zebrin II. At higher antibody concentrations, a weak glial cross reactivity is seen in most other brain regions: we believe that this is probably nonspecific. Zebrin II+ Purkinje cells are clustered together to form roughly parasagittal bands interposed by similar non-immunoreactive clusters. In all there are 7 zebrin II+ and 7 zebrin II− compartments in each hemicerebellum. One immunoreactive band is adjacent to the midline; two others are disposed laterally to each side in the vermis; there is a paravermal band; and finally three more bands are identified in each hemisphere. Both in number and position, these compartments correspond precisely to the bands revealed by using another antibody, mabQ113 (anti-zebrin I). In both fish and rat the compartmentation revealed by zebrin II immunocytochemistry is related to the organization of cerebellar afferent and efferent projections and may provide clues as to the fundamental architecture of the vertebrate cerebellum.

Determinants of Parenting Stress: Illustrations from Families of Hyperactive Children and Families of Physically Abused Children

Abstract: Examines the relative contributions of environmental, child, and Parental characteristics to parent-child interactive stress for families of hyperactive children and those of physically abused children. In families of hyperactive children, difficult child characteristics represent a probable source of parent-child interactive stress, whereas in abusive families such stress more likely arises from parental characteristics and adverse environments. The role of maternal cognitions as a mediator of stress in the two types of families is considered and relevant research into maternal perceptions, maternal attributions, and maternal self-efficacy is reviewed. Recommendations for the study of maternal cognitions in the context of interactive stress include: studying the interface between cognition and affect; assessing cognitions as ongoing processes; examining the role of cognitions in mediating situational influences; adopting a systems framework; and establishing the modifiability of specific types of parenta...

Heparin for 5 Days as Compared with 10 Days in the Initial Treatment of Proximal Venous Thrombosis

Abstract: It is common practice to begin anticoagulant treatment of deep-vein thrombosis with a 10-day course of intravenous heparin, with warfarin added on day 5 to 10 and continued for several months. We performed a randomized, double-blind trial comparing a shorter course of continuous intravenous heparin (5 days, with warfarin sodium begun on the first day) with the conventional 10-day course of heparin (with warfarin sodium begun on the fifth day) in the initial treatment of 199 patients with acute proximal venous thrombosis documented by venography. The frequency of objectively documented recurrent venous thromboembolism was low and essentially the same in the two groups (7.1 percent in the short-course group vs. 7.0 percent in the long-course group). Because the observed difference between the groups was 0.1 percent in favor of the long-course group, it is unlikely (P less than 0.05) that a true difference in favor of this group would be greater than 7.5 percent; the difference could be as much as 7.3 percent in favor of the short-course group. Major bleeding episodes were infrequent, and the rate was similar in both groups. We conclude that a five-day course of heparin is as effective as a 10-day course in treating deep venous thrombosis. Furthermore, using the shorter course would permit earlier discharge from the hospital and thus offer substantial cost savings.

In vitro reconstruction of the respiratory central pattern generator of the mollusk Lymnaea.

Abstract: Most rhythmic behaviors such as respiration, locomotion, and feeding are under the control of networks of neurons in the central nervous system known as central pattern generators (CPGs). The respiratory rhythm of the pond snail Lymnaea stagnalis is a relatively simple, CPG-based behavior for which the underlying neural elements have been identified. A three-neuron network capable of generating the respiratory rhythm of this air-breathing mollusk has been reconstructed in culture. The intrinsic and network properties of this neural ensemble have been studied, and the mechanism of postinhibitory rebound excitation was found to be important for the rhythm generation. This in vitro model system enables a better understanding of the neural basis of rhythm generation.

Conversion of Methane by Oxidative Coupling

Abstract: (1990). Conversion of Methane by Oxidative Coupling. Catalysis Reviews: Vol. 32, No. 3, pp. 163-227.

Vigilance for predators: detection and dilution effects

Abstract: Grouped individuals are less vigilant for predators than solitary conspecifics because (1) grouping increases the likelihood of predator detection (detection effect) and (2) grouping makes it less likely that any given individual will be preyed upon (dilution effect). However, many models of vigilance behaviour consider only the detection effect, and the interaction of the two effects has been insufficiently considered. I present two models of vigilance behaviour and test them using data on the vigilance of elk, Cervus elaphus. The first model, based on the detection effect alone, is implicit in many published formulations of the relationship between vigilance and group size. Although it predicts the direction of the relationship between vigilance and group size, it provides a poor explanation of the form of the relationship. The second model incorporates both detection and dilution effects. Regression analysis on this “security model” indicates that the model provides a good prediction of both the direction and the form of the relationship between vigilance and group size, explaining 69% of the variance in vigilance frequency. The security model demonstrates that both detection and dilution are important in determining the frequency of vigilance behaviour but that the relative importance of these two effects changes across group size, with detection providing relatively less benefit as group size increases. However, even when groups are large, individuals should exhibit at least some vigilance because although dilution alone provides much protection from predation, even a low level of vigilance greatly increases the likelihood that an individual will survive repeated predation attempts.

Elastic energy storage in tendons: mechanical differences related to function and age

Abstract: We investigated the possibility that tendons that normally experience relatively high stresses and function as springs during locomotion, such as digital flexors, might develop different mechanical properties from those that experience only relatively low stresses, such as digital extensors. At birth the digital flexor and extensor tendons of pigs have identical mechanical properties, exhibiting higher extensibility and mechanical hysteresis and lower elastic modulus, tensile strength, and elastic energy storage capability than adult tendons. With growth and aging these tendons become much stronger, stiffer, less extensible, and more resilient than at birth. Furthermore, these alterations in elastic properties occur to a significantly greater degree in the high-load-bearing flexors than in the low-stress extensors. At maturity the pig digital flexor tendons have twice the tensile strength and elastic modulus but only half the strain energy dissipation of the corresponding extensor tendons. A morphometric analysis of the digital muscles provides an estimate of maximal in vivo tendon stresses and suggests that the muscle-tendon unit of the digital flexor is designed to function as an elastic energy storage element whereas that of the digital extensor is not. Thus the differences in material properties between mature flexor and extensor tendons are correlated with their physiological functions, i.e., the flexor is much better suited to act as an effective biological spring than is the extensor.

The spontaneous regression of cancer. A review of cases from 1900 to 1987.

Abstract: The literature on the spontaneous regression of cancer is reviewed from 1966 to 1987 to update reviews by Everson & Cole and by Boyd These authors reviewed all cases of spontaneous regression from 1900 to 1965 We then report the entire series from 1900 to 1987 We also attempted to determine what attributions for spontaneous regressions have been reported Although almost half of the authors failed to speculate or specify a possible cause for the spontaneous regression, the remainder postulated responsible factors such as immunological or endocrine, surgical, necrosis, infection, or operative trauma The only unorthodox treatment to appear in the literature was the psychological We conclude that the literature on the spontaneous regression of cancer is still unable to provide unambiguous accounts of the mechanisms operating to affect these regressions

The use of FFT techniques in physical geodesy

Abstract: SUMMARY The fast Fourier transform (FFT) technique is a very powerful tool for the efficient evaluation of gravity field convolution integrals It can handle heterogeneous and noisy data, and thus presents a very attractive alternative to the classical, time consuming approaches, provided gridded data are available This paper reviews the mathematics of the FFT methods as well as their practical problems, and presents examples from physical geodesy where the application of these methods is especially advantageous The spectral evaluation of Stokes’, Vening Meinesz’ and Molodensky’s integrals, least-squares collocation in the frequency domain, integrals for terrain reductions and for airborne gravity gradiometry , and the computation of covariance and power spectral density functions are treated in detail Numerical examples illustrate the efficiency and accuracy of the FFT methods Key words: FFT, physical geodesy, spectral methods 1 INTRODUCTION Physical geodesy is the branch of geodesy which uses measured gradients of the anomalou6gravity potential T to determine a unique and coherent representation of the terrestrial gravity field at the Earth’s surface and in outer space The anomalous potential T is the difference between the actual gravity potential of the Earth and the reference potential of an ellipsoid with the same mass, flattening, and angular rotation rate as the Earth An approximation of T is needed to model geodetic measurements, to predict perturbations of satellite orbits, to determine global ocean circulation patterns, to assist global geophysics, and to support oil and mineral exploration In recent years, the amount of data available for the solution of this problem has increased dramatically, both in quantity and in type This has made the data processing problems more severe and has created a demand for efficient numerical solutions Since much of the data is available in gridded form, the use of fast spectral techniques was clearly appropriate Progress in the application of these methods to geodetic problems has been rapid during the last three years and it is almost certain that, because of their efficiency and accuracy, they will become standard procedures for a number of applications However, it has also become clear that geodetic and, more generally, geophysical data often present specific problems not usually encountered in typical electrical engineering applications The problems are with the heterogeneity of the data, the complicated surface on which they are given, the uneven spatial distribution, and the non-uniformity of the data noise This paper will discuss the use of

Are the soil microbial biomass and basal respiration governed by the climatic regime

Abstract: Soils in C equilibrium from various climatic regions were sampled to assess the influence of macroclimate on soil microbial biomass (C mic ) and basal respiration (CO 2 -evolution). C mic was measured using the substrate-induced respiration technique. C mic (μg C mic g −1 soil d.m.) was significantly correlated with several climatic variables, among them mean annual temperature (TEMP). At 20° and 5°C TEMP. 50 and 500 μg C mic g −1 soil were found, respectively. When C mic was calculated based on organic C (C mic -to-C org ratio), a very high correlation with precipitation/evaporation as the climatic variable was found. Of the variance 73% could be explained with the quadratic function y = 64.1− 109.5 x + 55.7 x 2 , where y = C mic -to-C org ratio (mg C mic g −1 C org ) and x = precipitation/evaporation. Soils from arid climates exhibited a high C mic -to-C org ratio (up to 50 mg C mic g −1 C org ). in soils from climates with balanced precipitation and evaporation (P/E = 1), the C mic -to-C org ratio was lowest (15mg C mic g −1 C org ). As P/E exceeds this, the C mic -to-C org ratio increased. Any deviation of the C mic -to-C org ratio from this regression line would indicate that a certain soil is not in C equilibrium but is losing or accumulating organic matter. In this study, for soils from a wide climatic range, the effects of pH, N or clay content on C mic and the C mic -to-C org ratio were small. For basal respiration, too, a significant relationship with climatic variables was found. Soils from warmer climates exhibited a basal respiration of 0.3 mg CO 2 g −1 soil h −1 compared to 0.1 mg for cooler climates. The metabolic quotient qCO 2 (μg respiratory CO 2 -C g −1 C mic h −1 ) increased with temperature.

Drop jumping as a training method for jumping ability.

Abstract: Vertical jumping ability is of importance for good performance in sports such as basketball and volleyball. Coaches are in need of exercises that consume only little time and still help to improve their players’ jumping ability, without involving a high risk of injury. Drop jumping is assumed to satisfy these requirements. This assumption is supported by a review of results of training studies. However, it appears that regular jumping exercises can be just as helpful. The same holds for exercises with weights, provided the subjects have no weight-training history. In fact, for unskilled jumpers who have no weight-training history, the effects of training programmes utilising these different exercises are additive. The most effective, efficient and safe way for a coach to improve the jumping achievement of his athletes may well be to submit them first to a training programme utilising regular jumps, then to a weight-training programme and finally to a drop jump training programme. In drop jump training programmes themselves, the improvement in jumping height varies greatly among studies. This variation cannot be explained satisfactorily with the information available on subjects and training programmes. Given the current state of knowledge, coaches seem to have no other option than to strictly copy a programme which has proved to be very effective. Obviously there is a need for more systematic research of the relationship between design and effect of drop jump training programmes. The most important variable to be controlled is drop jumping technique. From a review of biomechanical studies of drop jumping, it becomes clear that jumping technique strongly affects the mechanical output of muscles. The biomechanics of 2 techniques are discussed. In the bounce drop jump the downward movement after the drop is reversed as soon as possible into an upward push-off, while in the countermovement drop jump this is done more gradually by increasing the amplitude of the downward movement after landing. It is speculated that the bounce drop jump might trigger improvement of the power output capacity of muscles, whereas the repetition of the countermovement drop jump may help to improve coordination. Future training studies are needed to determine whether drop jumping technique really affects the outcome of the training, and if so, which technique should be preferred. Also, further biomechanical research is needed to determine kinematics and kinetics of other drop jumping techniques, and to trace potential dangers. The author urges for a close cooperation between coaches and scientists in future research.

Haemophilia B: database of point mutations and short additions and deletions, 7th edition.

Abstract: The seventh edition of the haemophilia B database lists in easily accessible form all known factor IX mutations due to small changes (base substitutions and short additions and/or deletions of <30 bp) identified in haemophilia B patients. The 1535 patient entries are ordered by the nucleotide number of their mutation. Where known, details are given on: factor IX activity, factor IX antigen in circulation, presence of inhibitor and origin of mutation. References to published mutations are given and the laboratories generating the data are indicated.

An orally active inhibitor of leukotriene synthesis accelerates healing in a rat model of colitis.

Abstract: Leukotrienes (LTs) have been implicated as mediators of the inflammation and ulceration associated with ulcerative colitis and Crohn's disease. In the present study, the effects of a novel, orally active inhibitor of LT synthesis (MK-886) were examined in a rat model of chronic colitis. Colitis was induced by intracolonic administration of trinitrobenzenesulfonic acid. Colonic LTB4 synthesis was measured after incubation of tissue samples in vitro and by in vivo equilibrium dialysis. A single dose of MK-886 (10 mg/kg) significantly inhibited colonic LTB4 synthesis for greater than 24 h. Daily treatment with this dose significantly reduced colonic damage, as assessed macroscopically and histologically, when the treatment was performed 2 h before induction of colitis and daily thereafter for 1 wk, but not when treatment was performed during the second week after induction of colitis. A less marked beneficial effect of MK-886 was observed when the pretreatment dose was excluded, suggesting a role for LTs in the early events of the inflammatory process. Inhibition of LT synthesis during the first 24 h after induction of colitis did not alter the extent of infiltration of neutrophils into the colon, as measured by tissue myeloperoxidase activity. Daily treatment with sulfasalazine (100 mg/kg po) either during the first or second week after induction of colitis did not significantly affect the rates of healing. At the dose used, sulfasalazine only produced a transient inhibition of colonic LTB4 synthesis. This study therefore demonstrates that a specific, orally active inhibitor of LT synthesis can significantly accelerate healing in this animal model of colitis when the treatment is performed during the early phase of the inflammatory response.

Effectiveness of intermittent pneumatic leg compression for preventing deep vein thrombosis after total hip replacement

Abstract: A randomized trial was performed in consecutive patients undergoing total hip replacement to evaluate the effectiveness of sequential intermittent calf and thigh compression for preventing venous thrombosis compared with a control group given no prophylaxis. Both groups underwent case finding for deep vein thrombosis using combined fibrinogen I 125 leg scanning, impedance plethysmography, and venography. Deep vein thrombosis by venography was present in 77 (49%) of 158 control patients compared with 36 (24%) of 152 patients given intermittent compression. Proximal vein thrombosis was present in 42 controls (27%) compared with 22 patients (14%) given intermittent compression. Combined impedance plethysmography and leg scanning was insensitive in this patient group (sensitivity, 46%); venography was required to detect more than half the patients with venous thrombosis. Sequential intermittent leg compression clinically and statistically significantly reduced the frequency of both proximal vein and calf vein thrombosis. Case finding resulted in early detection and treatment of patients with venous thrombosis.

Short latency ocular-following responses in man.

Abstract: The ocular-following responses elicited by brief unexpected movements of the visual scene were studied in human subjects. Response latencies varied with the type of stimulus and decreased systematically with increasing stimulus speed but, unlike those of monkeys, were not solely determined by the temporal frequency generated by sine-wave stimuli. Minimum latencies (70-75 ms) were considerably shorter than those reported for other visually driven eye movements. The magnitude of the responses to sine-wave stimuli changed markedly with stimulus speed and only slightly with spatial frequency over the ranges used. When normalized with respect to spatial frequency, all responses shared the same dependence on temporal frequency (band-pass characteristics with a peak at 16 Hz), indicating that temporal frequency, rather than speed per se, was the limiting factor over the entire range examined. This suggests that the underlying motion detectors respond to the local changes in luminance associated with the motion of the scene. Movements of the scene in the immediate wake of a saccadic eye movement were on average twice as effective as movements 600 ms later: post-saccadic enhancement. Less enhancement was seen in the wake of saccade-like shifts of the scene, which themselves elicited weak ocular following, something not seen in the wake of real saccades. We suggest that there are central mechanisms that, on the one hand, prevent the ocular-following system from tracking the visual disturbances created by saccades but, on the other, promote tracking of any subsequent disturbance and thereby help to suppress post-saccadic drift. Partitioning the visual scene into central and peripheral regions revealed that motion in the periphery can exert a weak modulatory influence on ocular-following responses resulting from motion at the center. We suggest that this may help the moving observer to stabilize his/her eyes on nearby stationary objects.