Showing papers by "University of Victoria published in 1975"

A decalification method for ultrastructure of echinoderm tissues.

Abstract: Decalcification of echinodcrm tissues for electron microscopy can be achieved after glutaraldehyde-osmium firation by treatment with a 1:1 mixture of 2% ascorbic acid and 0.3 M NaCI for 12-24 hours. Electron photomicrographs of material decalcified by this procedure are superior to those from EDTA-treated tiasue and show few of the deleteriour effects produced by EDTA.

Algorithm 495: Solution of an Overdetermined System of Linear Equations in the Chebychev Norm [F4]

Abstract: Received 3 June 1974 and 28 January 1975. Copyright (~) 1975, Association for Computing Machinery, Inc. General permission to republish, but not for profit, all or part of this material is granted provided that ACM's copyright notice is given and that reference is made to the publication, to its date of issue, and to the fact that reprinting privileges were granted by permission of the Association for Computing Machinery. Authors' addresses: I. Barrodale, Department of Mathematics, Umversity of Victoria, Victoria, B.C., Canada; C. Phillips, Department of Computational and Statistical Science, Umversity of Liverpool, Liverpool, England.

Current concepts concerning radioprotective and cryoprotective properties of dimethyl sulfoxide in cellular systems.

Abstract: Low concentrations (less than 1%) of both DMSO and glycerol gave surprisingly good cryoprotection to mammalian cells in tissue culture. Dextrans of varying molecular weight were cryoprotective. Combinations of these dextrans with small and essentially undamaging (in an osmotic sense) amounts of either DMSO or glycerol resulted in additive cryoprotection, and in some instances in synergism. Glycerol was as effective as DMSO in these combinations. If combinations of clinically acceptable dextrans (Rheomacrodex) and glycerol provide as much protection against freezing damage to other cell and tissue systems as they do to Chinese hamster cells in tissue culture, as demonstrated in this paper, then it should be possible to preserve tested or transplanted bone marrow, lymphocytes, platelets, and other cells without either the osmotic damage associated with high concentrations of glycerol or the toxicity problems associated with the cryoprotectant (DMSO or glycerol).

The Ramsey number for stripes

Abstract: If G1,…,Gc are graphs without loops or multiple edges there is a smallest integer r(G1,…,Gc) such that if the edges of a complete graph Kn, with n ≧ r(G1,…,Gc), are painted arbitrarily with c colours the ith coloured subgraph contains Gi as a subgraph for at least one i. r(G1,…Gc) is called the Ramsey number of the graphs G1,…,Gc.

Neurobiology of Stomotoca. II. Pacemakers and conduction pathways

Abstract: Evidence is presented for separate conduction pathways for swimming and for tentacle coordination in the marginal nerves of the jellyfish Stomotoca. The effector muscles are fired through junctions sensitive to excess Mg++, probably represented by the neuromuscular synapses observed by electron microscopy. The swimming effector (striated muscle) fires one-to-one with nerve input signals and myoid conduction occurs. Tentacle responses (smooth muscle contractions) involve facilitation, presumably at the neuro-effector junction; responses are graded and nonpropagating. Electrical correlates of two further conducting systems using the marginal nerves have been recorded. Their functions are unknown. One, the bridge system, extends up the four radii and encircles the peduncle; the other (ring system) is confined to the margin. A fifth conducting system is inferred in the case of the pointing response and its distribution is plotted. Signals have not been obtained from it. Pointing is accompanied by a burst of muscle potentials in the radial smooth muscles and is exhibited after a lengthy latency, indicating a local pacemaker. A sixth conducting pathway is the epithelial system, which mediates crumpling, a response involving the radial muscles without pacemaker intervention. Characteristic conduction velocities and wave forms are noted for the first four systems and for epithelial pulses. All systems, except perhaps the pointing conduction system, through-conduct under excess Mg++. Spontaneous activity patterns are described for the swimming, tentacle pulse, and ring systems. Abrupt increases in light intensity inhibit spontaneous activity, sudden decreases augmenting it. In the absence of specialized photoreceptors, light is presumed to act directly on central neurons. Epithelial pulses inhibit swimming, apparently by blocking the generation or conduction of the primary nervous events. This observation, taken in conjunction with evidence of feedback inhibition of the primary swimming system by the cells it fires, is discussed in relation to possible mechanisms whereby the output of nerve cells might be altered by activity in the excitable epithelial cells which envelop them.

Neurobiology of Stomotoca. I. Action systems.

Abstract: The layout of nerves, muscles, and conducting epithelia is described for the simple hydrozoan medusa Stomotoca. Comparisons are drawn with Sarsia and other recently studied forms. The major action systems are those responsible for swimming, crumpling (protective involution), tentacle posture, pointing (unilateral reciprocal flexions of the manubrium and margin), and visceral movements (barely mentioned). Crumpling is a simple summating response in this species. Crumpling and pointing are considered to use the same effectors but different conduction pathways. New histological results include the demonstration of a nerve plexus running through the endodermal canal system and a nerve plexus in the ectoderm encircling the peduncle. Special attention is given to the distribution of synapses and gap junctions, as possible trasmission pathways in behavioral responses. Some details are included on organization within the marginal nerve rings.

Staocysts of hydromedusae.

Abstract: The statocysts of Leptomedusae are formed as a depression in the velum. They are lined on the inside towards the distal part of the velum by thin epithelium and towards the proximal part by ciliated sensory cells. Lithocytes are present in the centre. The concretion contains calcium sulphate and in some cases, calcium phosphate is also present in addition to some membranous material.

Bacteria associated with the gills of salmonid fishes in freshwater.

Abstract: The bacteria on the gills of 7 species of freshwater salmonid fishes were examined qualitatively and quantitatively. Both wild and hatchery cultured salmonids were examined. The former were obtained from 12 different locations in British Columbia. Species of Pseudomonas and Cytophaga predominated on both groups of fish. The microflora of the wild fish also contained Aeromonas and members of the Brevibacterium–coryneform–Erysipelothrix group. The microflora of cultured fish was less varied. As many as 106 viable organisms/g wet weight of gill tissue were recovered.

Antibacterial Activity of Tropolone

Abstract: Tropolone was shown to be bacteriostatic and bactericidal for a wide range of bacterial species. This antibacterial activity was quantitated using standard methods. Tropolone treatment of whole cells resulted in cell lysis characterized by bleb formation and subsequent loss of cell contents after rupture of the bleb. Although bleb formation and lysis did not occur in the presence of 20% sucrose, cell viability was lost. Spheroplasts and protoplasts also lysed in the presence of tropolone. These results indicate that tropolone acts on the cell wall or envelope and on the plasma membrane.

The assessment of components involved in illusion formation using a long-term decrement procedure

Abstract: Available evidence seems to indicate that illusion decrement represents reorganization of cognitive components involved in visual-geometric illusions. Observers viewed one of the two forms of the Mueller-Lyer illusion, containing differential opportunities for peripheral structural interactions, for a 10-min test session on each of 5 successive days. The magnitude of the distortion decreased to a different asymptotic level in each of the two configurations with the form, with more opportunity for structural interactions showing the higher asymptote. Thus, this asymptote probably represents the structural or physiological contribution to the illusory distortion.

Cultural differences in children's concepts of reading and writing

Abstract: Summary. Previous research has indicated that children enter the task of learning to read in a state of cognitive confusion regarding the function and nature of the task. The present investigation was addressed to the hypothesis that cultural differences in home background are an important influence in the development of children's understanding of the purpose of writing and their concepts of the language units employed in the written code. 92 non-Indian Canadian children at kindergarten were compared with 72 kindergarten pupils from two Indian bands in which there is no tradition of literacy and a poverty of experiences of writing and formal concern with language analysis. On all five measures used the Indian children scored significantly lower. They were less able to recognise literacy activities, less cognisant of their purpose, and had poorer technical knowledge of units of speech and writing.

Engagement with an old theory.

Abstract: The co-author of Disengagement Theory restates the central propositions, suggests new studies that might test its usefulness, and examines some of the controversy that has been generated over the years either by the theory itself or the context in which it was set forth. The four key propositions focus upon decreasing life space with advancing age, the individual's own anticipation and participation in this process, a change in style of interaction, and the momentum of the disengagement process once it has begun. Although some useful research has been done, the theory remains poorly operationalized and largely untested. A measure of life space variety is proposed, and attention also directed to neuro-physiological findings. Several misunderstandings and misapplications of Disengagement Theory are discussed, including the erroneous idea that disengaged people necessarily are either higher or lower in morale than others, and the unenlightening controversy over “activity versus disengagement.”

Faculative Anaerobic Bacteria in the Digestive Tract of Chum Salmon (Oncorhynchus keta) Maintained in Fresh Water Under Defined Culture Conditions

Abstract: The bacterial flora in the digestive tract of chum salmon growing in fresh water under defined and controlled culture conditions was examined both qualitatively and quantitatively. The predominant species present in the digestive tract were identified as Aeromonas, with Aeromonas hydrophila being the most common isolate. These aeromonads were not isolated from the diet. Other bacterial species commonly isolated included Bacillus, Enterobacter, nonpigmented pseudomonads, Micrococcus, and Acinetobacter. These species were also isolated from the diet or tank water. As many as 10-8 viable bacteria per g (wet weight) of digestive tract plus contents were counted. After 75 days of starvation, 10-6 viable bacteria were counted, whereas fish fed a sterile feed contained 10-5 viable bacteria per g (wet weight) of digestive tract plus contents.

Urban ecological and household correlates of stress-alleviative drug use.

Abstract: Experiments in animal biology are the major source of data relating the spatial distribution of populations to stress and its ultimate pathological consequences. The findings of these experiments are clear, dramatic, and relatively consistent: they suggest that population spatial characteristics such as high density, overcrowding and congestion lead to a variety of pathological conditions including aggression, decreased reproductive behavior, and heightened rates of morbidity and mortality (Calhoun, 1962; Theissen, 1964; Christian and Davis, 1964; and Freedman, 1973).

Instructor-Paced, Mass-Testing for Mastery Performance in an Introductory Psychology Course

Abstract: The PSI method of weekly testing with a mastery criterion appears to be sufficient to produce improved learning economically.

The energy budget of man: variations with aspect in a downtown urban environment.

Abstract: The energy budget of man is computed and used to assess the microclimatic variation that can occur in a downtown urban environment through the effects of direction of exposure and open sky view factor. On sunny days the exposure to direct beam solar radiation was the most important factor in creating climatic differences. This directly contributed energy to man and warmed the radiant and air temperature environments. On a cloudy day very little variation in the radiation, temperature and humidity regimes occurred. Wind became the dominant factor with man experiencing a greater heat loss at windward locations. With the assumptions used in this study convective heat flux was responsible for the greatest heat losses in man.