Showing papers by "University of Saskatchewan published in 1969"

Absorption of Microwaves by Microorganisms

Abstract: RECENTLY S. J. W. and Dodds reported that 136 GHz microwaves interfere with the growth of Escherichia coli cells1. Here we report further investigations of the absorption of 65 to 75 GHz microwaves by cells of E. coli BR as well as isolated protein, RNA and DNA, and its effect on some metabolic processes. Our equipment has been described1,2. Cells were grown for 24 h at 37° C in nutrient broth (NB) and either (a) washed twice in 0.85 per cent NaCl and deposited as a pellet by centrifugation or (b) resuspended after washing to a cell concentration of 1 × 106 cells/ml. in 0.5 per cent glucose + 0.5 per cent casamino-acids + 50 µg/ml. thymine in 0.1 M phosphate buffer, pH 6.9 (GCT). To examine the effect of microwaves on cell growth, 0.5 ml. aliquots of cells suspended in GCT were placed in vials 1.5 cm in diameter. Some vials were put on top of microwave horns and others incubated at the same temperature (25° C) out of the radiation field. At various times the vials were removed and the number of cells/ml. determined by dilution and plating on nutrient agar. The effect of microwave absorption on metabolic processes was investigated by resuspending the washed cells to a concentration of 1 × 108 cells/ml. in 1.0 per cent glucose in 0.1 M phosphate buffer, pH 6.9. Aliquots of 0.2 ml. of this suspension were placed in the vials and after positioning on the microwave apparatus 0.3 ml. of a solution was added, which contained 0.8 µCi/ml. of one of the following: thymine-2-14C, uracil-2-14C or algal 14C protein hydrolysateplus two of the following: unlabelled thymine, 50 µg/ml.; uracil, 100 µg/ml.; or casamino-acids, 500 µg/ml. After various times the cells from each vial were deposited onto a Millipore filter and washed with 100 ml. of 1 N HCl; the filter was dried and radioactivity counted. The microwave absorption spectra of the cells, H2O, protein, RNA and DNA were obtained by making films of the material on a thin mica window. The films were dried at 80 per cent relative humidity and covered with a second thin piece of mica. The difference between the microwave absorption of a blank and the film gave the absorption spectrum of the film of cells or biological material.

Composite System Reliability Evaluation

Abstract: This paper illustrates the application of a conditional probability approach to the determination of a reliability index at any point in a composite system. A general design criterion is postulated in terms of quality of service rather than continuity. Using a Markov approach, it is shown that the effect of storm associated failures on the system failure probabilities is dependent upon the degree of redundancy in the configuration under study. The effects of shunt compensation, on-load tap changing, and variations in allowable voltage levels on the reliability of a simple configuration are illustrated. Using the techniques described in this paper, it is possible to arrive at a measure of steady-state adequacy for any point in a system and, particularly, at those points at which major transmission terminates and subtransmission begins.

Competitive Exclusion between Microtus and Clethrionomys in the Aspen Parkland of Saskatchewan

Abstract: Habitat preferences of Microtus pennsylvanicus and Clethrionomys gapperi were noted in the aspen parkland near Saskatoon, Saskatchewan (52°10’N, 106°41’W). An almost complete habitat separation was observed between the two species. In summer, in an area where both species occurred in numbers, resident Clethrionomys were confined to an aspen stand, whereas resident Microtus were in adjacent grassland. Where Clethrionomys were absent, resident Microtus favored habitat normally used by Clethrionomys. Late autumn trapping suggests that in winter the two species coexist in the same aspen stand where there is a protective cover of snow. The data suggest competitive exclusion of Microtus by Clethrionomys from aspen habitat during the summer. The possibility of a beachhead phenomenon and the exclusion of Clethrionomys by Microtus from certain habitats is considered.

Samarium, Europium, and Ytterbium Electrode Potentials in LiCl ‐ KCl Eutectic Melt

Abstract: Samarium, europium, and ytterbium displace the alkali metals from their molten chlorides, forming the divalent species Sm (II), Eu (II), and Yb (II) in solution. Progressive coulometric reduction of solutions of , and , enabled the redox potentials to be measured vs. ; ; . Potentials of ytterbium systems starting from both and were followed over a ~200°C interval and from , Δ S° and H° for the reaction were found to be 22 cal/deg−1 mole−1 and 54.5 kcal/mole−1, respectively, close to the values for pure decomposition. No evidence of disproportionation of Sm(II), Eu(II), and Yb(II) was found but scrupulous precautions were needed to keep the solvent free from impurities which readily react with the highly reducing ions, especially Sm(II). Considerable experimental details are included.

Enzymic degradation of heparin A sulphamidase and a sulphoesterase from Flavobacterium heparinum

Abstract: A sulphamidase and a sulphoesterase were isolated from adapted cells of Flavobacterium heparinum. These enzymes were partially purified from the `heparinases' present in the bacterial extracts and characterized. The sulphamidase has a high specificity for glucosamine N-sulphate and glucosamine 2,6-disulphate. The activity decreases sharply with increasing molecular weight of the substrates tested. The sulphamidase and the sulphoesterase activities were distinguished from each other by their different sensitivities to concentration of phosphate ion and to temperature. The importance of these enzymes in the study of the structure of heparin is discussed.

Reliability and factorial validity of the Wallach-Kogan creativity tests.

Abstract: The Wallach-Kogan tests of ‘creativity’ and the Primary Mental Abilities test were administered to 207 university students. The creativity tests were scored for originality, and KR20 reliabilities calculated. Intercorrelations among the five creativity tests were also calculated and compared with those among the six ‘intelligence’ tests. Results indicated that the Wallach-Kogan tests were highly reliable, clustered strongly among themselves, and correlated poorly with the intelligence tests. A factor analysis indicated the existence of large loadings of creativity tests on the intelligence factor, and of intelligence tests on the creativity factor.

Correlation between decreases in brain gamma-aminobutyric acid levels and susceptibility to convulsions induced by hyperbaric oxygen.

Abstract: : The susceptibility of mice to seizures at hyperbaric pressures of oxygen (OHP) was placed on a quantitative basis and compared with the corresponding rate of decrease in brain GABA concentration. The influence of small amounts of carbon dioxide in the breathing mixture on these effects of OHP was also determined. A correlation between the rate of decrease in GABA and susceptibility to seizures was shown to exist not only over the varying oxygen pressures and varying concentrations of carbon dioxide used in the present experiments but also over varying animal species (a previous study). The critical oxygen pressure for decreases in brain GABA to occur was shown to be 30 p.s.i.g. This value agreed closely with the well documented critical pressure necessary to produce seizures in both animals and man. The probability that lowered brain GABA levels play a major role in the etiology of OHP convulsions was discussed. (Author)

Efferent projections of the anterior olfactory nucleus.

Abstract: The efferent projection fibers from the rostral and the medial segments of the anterior olfactory nucleus have been studied using the Nauta or the Fink modification of the Nauta method for degenrating axons. Lesions were suitably placed by electrocoagulation. From the rostral segment of the anterior olfactory nucleus efferent fibers by way of the bulbar part of the anterior commissure were traced to the internal granular and the mitral cell layer of the normal side. Preterminal and terminal degeneration were traced by way of the homolateral lateral olfactory tract and these fibers ended in the lateral two-thirds of the olfactory tubercle, the prepiriform, the piriform and the periamygdalar cortices and into the corticomedial segment of the amygdaloid complex. Degenerating fibers were also noted in the dorsomedial nucleus, the lateral habenular nucleus, the lateral hypothalamic area and in the supraoptic area of the same side where the lesion was made. In animals where the lesion was placed in the medial segment of the anterior olfactory nucleus the same fiber distribution was observed as reported when the lesion was placed in the rostral segment of the anterior olfactory nucleus. However, other areas were observed receiving fibers from the medial segment of the nucleus. These areas were the basolateral segment of the amygdaloid complex and the mammillary areas.

Detailed Analysis of a Two-Stage Four-Way Electrohydraulic Flow-Control Valve:

Abstract: A detailed analysis is given of a flow-compensated, two-stage, four-way, closed-ports electrohydraulic flow-control valve Factors considered in the analysis of the first stage include: the electromagnetic forces generated by the torque motor, impedance of the motor coil, inertia of the flapper, viscous damping forces, spring forces, pressure feedback forces, and leakage flow Factors considered in the analysis of the second stage include the acceleration force on the spool, viscous friction forces, restraining spring forces, flow reaction forces, leakage flow, and the compressibility of the oilExperimental verification of the analytical work is included

Performance and Learning in a Discrete Motor Task under Massed Vs. Distributed Practice

Abstract: Three hundred male subjects, assigned in systematic rotation to five experimental groups (N = 60 in each) which differed in amount of distribution of practice, were tested on a discrete-trial motor learning task, the peg turn All subjects were given 120 practice trials (60 trials a day), on two days separated by a 48-hour rest Even though the peg turn task is inherently distributed, reminiscence did occur when the massing was made as large as practically possible The amount of reminiscence depended upon the stage of practice Warm-up decrement occurred in the peg turn under both massed and distributed practice conditions; the longer the rest, the greater the amount Performance of the task under nonrhythmical conditions reduced the development of “set” during practice and thus decreased the amount of warm-up decrement after rest Increased amounts of massing did have a deleterious effect on performance, but did not reduce the amount learned

Physical fatigue and motor learning.

Abstract: In an attempt to investigate the effects of physical fatigue upon the learning of a motor skill, 75 college women were assigned in systematic rotation to either a control group or to one of two experimental groups (N = 25 in each group). All subjects were given a total of 50 trials on the pursuit rotor: 25 trials on Day 1, the practice session; and 25 trials on Day 2, the test session. One of the experimental groups was fatigued early in the practice session while the other was fatigued late in the practice session. Fatigue interpolated early and late was detrimental to subsequent performance improvements but had no effect upon the amount learned.

Formation of Banded Sulphides: Metal Ion Separation and Precipitation by Inorganic and Microbial Sulphide Sources

Abstract: WHEN two ions capable of forming insoluble precipitates are brought together by diffusion through gels, sharp bands of precipitate are formed. This phenomenon was discovered by Liesegang1, who recognized its possible geological significance.

Growth and rotation of Flammulina velutipes fruit bodies and the dependence of stipe elongation on the cap

Abstract: transferred from 21 + 1 C to 16 ± 1 C than in cultures maintained continuously at the higher temperature. However, large fruit bodies also formed at 21 + 1 C. Growth curves are presented for stipe elongation and cap expansion at 16 - 1 C, and spiral growth of the stipe was measured by the rotation of the cap. The maximum speed of rotation varied considerably (15-50°/12 hr), and, at least up to 3 cm fruit body length, the preferred direction of rotation was clockwise as viewed from above. Reversal from clockwise to counter-clockwise rotation was observed in 2 of 10 fruit bodies. Decapitation of fruit bodies at different lengths caused a rapid decrease in stipe elongation without recovery, and demonstrated that stipe growth depends on the cap during most of the growth period. This dependence was strongest in younger fruit bodies but was detectable even at 7-7.9 cm, the upper limit tested. Removal of approximately j of the cap, leaving only a narrow symmetrical cap slice with lamellae, reduced growth significantly in young fruit bodies of 1.5-2.4 cm length, but not at close to 3 cm. Growth studies after removal of either the lamellae or the cap trama from cap slices showed that stipe elongation depends on the lamellae and not on the cap trama. Unexpectedly, the stipes did not curve either in darkness or in light, despite continuing elongation, when half cap slices with lamellae were left attached to one side of stipes at 1.2-3.7 cm length. Half of the whole cap also failed to induce negative curvature. The findings for Flammulina velutipes are compared with those reported for Agaricus bisporus.

Knives as Aggression-Eliciting Stimuli:

Abstract: An experiment was conducted to explore the cue value of the object “knife” in displaced aggression. Three kinds of knives were used: (1) a switchblade knife (high aggressive cue value), (2) a carving knife (high or low aggressive cue value), and (3) a table knife (low aggressive cue value). It was expected that frustration in the presence of highly aggressive cues (the switchblade knife and possibly the carving knife) would lead to more intense aggression than frustration in the presence of low-aggressive cues (the table knife and the no-object control conditions). Because of differences in roles and social learning males and females would react differently. 64 male and female university students were either frustrated or not frustrated in the presence of either a switchblade knife, carving knife, table knife or no object and then given an opportunity to evaluate an innocent peer on a 12-adjective bipolar scale. Ss were also asked to complete Zuckerman's (1960) Multiple Affect Attitude Check List (MAACL)....

Electron microscopic observations on the juxtamedullary efferent arterioles and Arteriolae rectae in kidneys of rats.

Abstract: Efferent arterioles leaving juxtamedullary glomeruli in the kidneys of rats have a media comprized of a layer of closely packed smooth muscle cells. This muscle coat continues along the length of the efferent arterioles and arteriolae rectae to a level deep in the outer medullary zone, where smooth muscle cells are gradually replaced by pericytes characteristic of the non-muscular arterial vasa recta.