Showing papers by "University of Calgary published in 1978"

Sessile bacteria: An important component of the microbial population in small mountain streams 1

Abstract: Direct counts by epifluorescence microscopy demonstrated that epilithic bacteria were numerically more important than free-floating bacteria in unpolluted mountain streams Concentrations of sessile bacteria associated with the upper surfaces of submerged rocks coincided with fluctuations in epilithic algal biomass Electron microscopy of thin-section preparations of natural samples showed that the attached algae provided a surface for bacterial colonization This close physical relationship between the bacteria and algae was mediated by a network of fibers which, in mass, appeared as a layer of slime covering the streambed The relationship between sessile bacterial concentratons and epilithic algal biomass in one tributary suggested that, in some cases, factors other than epilithic primary production governed the attached microbial population

On numbers and games

Abstract: Some readers know to play the game of nim well, fewer play a perfect annihilation game, and nobody knows whether there exists an opening move in chess that will guarantee a win for white. These games and many more, belong to the family of combinatorial games, by which we mean the set of all two-player perfect-information games without chance moves and with outcomes lose or win (and sometimes: dynamic tie). The motivation for ONAG may have been, and perhaps was-and I would like to think that it was-the attempt to bridge the theory gap between nim-like and chess-like games. Why is there a gap? Every combinatorial game can be described as a directed graph called game-graph, whose vertices are the game positions, and (u, v) is a directed edge if and only if there is a move from position u to position v. Denote by N the set of all positions from which the Next (first) player can force a win; by P the set of all positions from which the Previous (second) player can force a win; and by T the set of all (dynamic) Tie positions, which are positions from which no player can force a win and therefore both can avoid losing. In an acyclic game-graph there cannot be any tie positions. The N, P, T classification of any game graph R = (V, E) can be determined in 0(\V\ + \E\) steps [8]. For both nim and chess, a finite game-graph can be constructed and the N, P, T classification can be determined. So both games are solvable in principle. If we play nim with n piles, each pile containing at most k tokens, then the game-graph contains (k + \) vertices. Suppose that in (generalized) chess played on an « X « board there are k different pieces. If k is about n/2, then the game-graph of chess contains O (2") vertices. So both game-graphs have exponentially many vertices, and thus both games appear intractable in the usual sense of computational complexity [1, Chapter 10], [14, Chapter 9], namely a computation appears to be required which is asymptotically exponential. From a computational efficiency standpoint, the essential difference between nim and chess is that nim can be viewed as a disjunctive compound (sum) of independent games, namely the individual piles. A disjunctive

Depression and causal attributions for success and failure.

Abstract: The present study investigated the effects of depression on causal attributions for success and failure. Specifically, female university students were separated into depressed and nondepressed groups on the basis of Costello--Comrey Depression Scale scores, and then received either 20%, 55%, or 80% reinforcement on a word association task. Following the task, attributions were made for outcome using the four factors of effort, ability, task difficulty, and luck. In accord with predictions generated from a self-serving biases hypothesis, nondepressives made internal (ability, effort) attributions for a successful outcome (80% reinforcement) and external attributions (luck, task difficulty) for a failure outcome (20% reinforcement). As predicted from consideration of the self-blame component of depression, the attributions made by depressives for a failure outcome were personal or internal. Contrary to expectations, depressives also made internal attributions for a successful outcome. The findings for depressives were discussed in relation to the recently revised learned helplessness model of depression, which incorporates causal attributions. For nondepressives, the findings were considered in terms of the self-serving biases hypothesis.

Intermittent two phase flow in horizontal pipes: Predictive models

Abstract: A semi-mechanistic model for two phase gas-liquid slug flow proposed recently by Dukler and Hubbard has been modified and extended to apply to the entire intermittent flow regime. Flow predictions of the model proposed in this paper are compared with detailed experimental data recently obtained for an air-oil system. The model requires the use of empirical correlations for the slug velocity and the in situ liquid volume fraction in the slug. In addition, either the slug frequencies or length corresponding to the given design conditions must be known. However, calculated values of average pressure gradient and in situ liquid volume fraction are relatively insensitive to these latter parameters, and in fact, good results are obtained assuming a constant slug length. The paper includes a discussion of the limitations of the proposed model and the expected direction of further study required to extend its mechanistic aspects.

Structural Analysis: A Unified Classical and Matrix Approach

Abstract: Introduction to the analysis of statistically indeterminate structures force method of analysis displacement method of analysis use of force and displacement methods strain energy and virtual work method of virtual work and its application to trusses further applications of method of virtual work important energy theorems - Betti's and Maxwell's theorems, application of Betti's theorem to transformation of forces and displacements, Engesser's theorem of compatability, Castigliano's theorem of compatability, Catigliano's theorems displacement of elastic structures by special methods application of the force method - column analogy application of the displacement method - slope deflection and moment distribution moment distribution with sway - multistorey and multibay frames influence lines for beams, frames and grids - Muller-Breslau's principle influence lines for arches, trusses and prestressed concrete members effects of axial forces analysis of shear-wall structures method of finite differences analysis of plates by finite differences finite-element method further development of finite-element method plastic analysis of continuous beams and frames yield-line and strip methods for slabs structural dynamics computer analysis of framed structures implementation of computer analysis. Appendices: matrix algebra, displacements of prismatic members, fixed-end forces of prismatic members, end-forces caused by end-displacements of prismatic members, reactions and bending moments of supports of continuous beams due to unit displacement of supports, properties of geometrical figures, torsional constants, values of the integral, deflections of a simple beam of constant EI subjected to unit end-moments, geometrical properties of some plane areas commonly used in the method of column analogy, forces due to prestressing.

The thermodynamic properties of reciprocal solid solutions

Abstract: A multisite solid solution of the type (A, B) (X, Y) has the four possible components AX, AY, BX, BY. Taking the standard state to be the pure phase at the pressure and temperature of interest, the mixing of these components is shown not to be ideal unless the condition: $$\Delta G^0 = (\mu _{AX}^0 + \mu _{BY}^0 - \mu _{AY}^0 - \mu _{BX}^0 = 0$$ applies. Even for the case in which mixing on each of the individual sublattices is ideal, ΔG 0 contributes terms of the following form to the activity coefficients of the constituent components: $$RT\ln \gamma _{AX} = - X_{B_1 } X_{Y_2 } \Delta G^0$$ (X Ji refers to the atomic fraction of J on sublattice i). The above equation, which assumes complete disorder on (A, B) sites and on (X, Y) sites is extended to the general n-component case. Methods of combining the “cross-site” or reciprocal terms with non-ideal terms for each of the individual sites are also described. The reciprocal terms appear to be significant in many geologically important solid solutions, and clinopyroxene, garnet and spinel solid solutions are all used as examples. Finally, it is shown that the assumption of complete disorder only applies under the condition: $$\Delta G^0 \ll zn_1 RT$$ where z is the number of nearest-neighbour (X, Y) sites around A and n 1 is the number of (A, B) sites in the formula unit. If ΔG 0 is relatively large, then substantial short range oder must occur and the activity coefficient is given by (ignoring individual site terms): $$\gamma _{AX} = \left( {\frac{{1 - X'_{Y_2 } }}{{1 - X_{Y_2 } }}} \right)^{zn_1 }$$ where X′Y2 is the equilibrium atomic fraction of Y atoms surrounding A atoms in the structure. The ordered model may be developed for multicomponent solutions and individual site interactions added, but numerical methods are needed to solve the simultaneous equations involved.

Reactions of O-.2, H2O2 and other oxidants with sulfhydryl enzymes.

Abstract: — The inactivation of a number of sulfhydryl enzymes by H2O2. OH and O-2 is discussed. and the efficiencies of inactivation for the free radicals are compared with those of halide radicals. The enzymes with essential acyl-binding SH groups (papain and GAPDH) exhibit a higher sensitivity to inactivation by O-2 and H2O2 than those with “unactivated” SH groups (LDH and ADH). The sulfenic acid derivatives from the reactions of papain and GAPDH with H2O2 are repairable by RSH molecules, the rates of repair depending on the nature of the R group. Comparisons of rate constants show that competitive scavenging by RSH must be a very important mechanism for the protection of sensitive SH-containing proteins against OH, and for papain in oxygen-free solutions the efficiency of this protection increased in the order GSH < PenSH < CysSH < dithiothreitol. On the other hand, catalase and superoxide dismutase are more effective than RSH compounds in rendering protection against H2O2 and O-2. In fact in oxygen-containing systems the effects of RSH are highly complex, because the OH- and/or O-2-initiated chain oxidation of these molecules produces reactive species, which may inactivate essential SH groups. Experiments with papain showed that the yields and nature of the RSH-derived species depended on the structure of the R group. Also, very large yields of papain Cys25SSR were produced from the reactions of the radicals and H2O2. In effect, it is apparent that under certain conditions the oxidation of “activated” SH groups of important target molecules could become coupled to the OH or O-2 -initiated oxidation of RSH molecules. This should be taken into account in assessing the overall effectiveness of RSH compounds as cellular protectors.

A critical review of Seligman's laboratory experiments on learned helplessness and depression in humans.

Abstract: Six laboratory experiments on learned helplessness and depression in humans reported by Seligman and his colleagues were critically reviewed. They were found to provide little or no support for the learned helplessness theory of depression. A number of methodologica l and conceptual problems were discussed. In conclusion, it was suggested that heuristic theories such as Seligman's should be closely examined before psychologists embark on an extensive series of experimental tests. Seligman and his colleagues have conducted a number of laboratory experiments on learned helplessness and depression in humans. The findings have been considered by Seligman to provide support for his learned helplessness theory of depression, and one will usually find the reports of these experiments listed in writings about the theory. I shall attempt to show that the findings of his experiments provide little or no support for his theory. This review will be restricted to the six articles reporting experiments with humans that have been conducted by Seligman and his colleagues.1 It would seem particularly important at this stage to evaluate Seligman's own thinking and work in this area rather than to venture into an evaluation' of work in other laboratories that may be based on a misinterpretation of Seligman's ideas. The present article has been divided into three sections. In the first section, methodological and conceptual problems specific to each experiment will be noted. In the second section, these problems and some additional problems common to all of the studies will be discussed more generally. In the third section, I shall comment on the popularity of the learned helplessness theory. I shall also comment on the importance of scrutinizing the

Finding Minimal Center-Median Convex Combination Cent-Dian of a Graph

Abstract: The graph median and center problems are well known with numerous possible applications. The first is suitable for locating a facility providing a routine service, by means of minimizing the average distance of customers to it. The second is appropriate for emergency services where the objective is to have the furthest customer as near as possible to the center. In reality a combination of both, usually antagonistic, goals is common. This paper presents a procedure to locate a facility on a graph, such that a convex combination of the median and the center objective functions is minimized. The term “cent-dian” is coined for this point of the graph. Since it is usually difficult to assign precise weights to the two objectives, when they are convexly combined, the procedure generates the cent-dians for all possible combinations. Finally, an equivalent median problem on an expanded graph is presented.

Free ubiquitin is a non-histone protein of trout testis chromatin

Abstract: A NON-HISTONE chromosomal protein extracted from trout testis chromatin by 0.35 M salt, protein S, (ref. 1) has now been purified to homogeneity and its primary structure determined (Fig. 3) and shown to be identical with that of the thymus protein, ubiquitin2–4 (originally called thymopoietin) and sequenced by Schlesinger et al.5. Ubiquitin was previously reported in chromatin by Goldknopf et al.6 as a component of protein A-24 in which it is covalently bound by the α-carboxyl group of its C-terminal glycine to the e-amino group of lysine 119 of histone H2A in an isopeptide linkage7. Goldknopf and Busch8 have reported that protein A-24 is a component of the core nucleosomes of rat liver chromatin being present in quantities sufficient for it to be linked to H2A in 10–20% of the total nucleosomes. The present studies indicate clearly that ubiquitin can also occur as a free polypeptide in trout testis chromatin and is readily extracted by 0.35 M NaCl. Moreover, free trout testis ubiquitin (protein S) is rapidly released together with HMG-T (ref. 9) (and small amounts of Hl) during limited micrococcal nuclease digestion of trout testis chromatin and is probably also located in the linker regions of the chromatin. DNase I digestion does not release free ubiquitin preferentially10. In view of the pronounced biological effects of free ubiquitin on membrane adenyl cyclase of immature thymocytes3,4 and the ability of ubiquitin to promote the differentiation of these cells into mature T cells3,4, its occurrence in chromatin raises the possibility of a role of ubiquitin in cell differentiation and differential gene expression.

Acid base changes during recovery from disturbance and during long term hypoxic exposure in the lobster Homarus vulgaris

Abstract: Hemolymph O2 and CO2 levels and pH were measured in lobsters (H. vulgaris) as they settled in normoxic conditions and during prolonged exposure to moderately hypoxic seawater. Initial handling and transfer to the experimental conditions resulted in a marked acidosis. Complete recovery took from 24 to 48 hours. Samples of hemolymph taken after 48 hours yielded “settled” normoxic levels for O2 CO2 and pH. Subsequent exposure to moderately hypoxic water caused an initial respiratory alkalosis associated with pronounced hyperventilation. The induced pH change was sufficient to cause a marked increase in the oxygen affinity of the hemocyanin, allowing almost complete saturation of post-branchial (arterial) hemolymph despite a 3-fold decrease in hemolymph oxygen tension. Prolonged exposure to hypoxia resulted in an attenuation of the hyperventilation response but hemolymph bicarbonate levels rose substantially and may have maintained pH high and thus kept oxygen affinity above the normoxic level. On return to normoxic water both ventilation volume and hemolymph carbon dioxide decreased and pH and oxygen affinity returned to normoxic levels.

The structure of psychological revolutions.

Abstract: Four major revolutions within psychology (i.e., the behavioristic, cognitive, psychoanalytic, and humanistic) are briefly examined in an attempt to unearth their formal structures. The view put forth is that it is a transformation of the subject-object relation — an insight gleaned by an application of Ludwig Feuerbach's transformative method — which underlies major paradigmatic shifts within psychology. It is noted that psychological revolutions based upon a transformation of the subject-object relation could go on indefinitely in a vicious, circular manner. Thus, a revolution to end revolutions is called for (a dialectical revolution) in order to liberate psychologists from partialist, encapsulated, or limiting views of the subject-object relation.

Suppression of fever at term of pregnancy.

Abstract: THE newborn human is often unable to develop a fever following exposure to various infectious agents1–3 and newborn lambs are similar, in that they do not develop a fever in response to a bacterial endotoxin challenge in the first few days of life4. Lack of the febrile response is thought to be due to the need for a process of ‘sensitisation’ of the lambs, or to the immaturity of some aspect of the fever-production process5,6. Newborn guinea pigs and rabbits also, do not become febrile or show a diminished response to a challenge with endotoxin during early postnatal life7,8. We have examined the response of the pregnant ewe to pyrogens at and near the time of birth, for although they become febrile during pregnancy9, their response to endotoxin at term has not been studied. We report here that the febrile response induced by a bacterial endotoxin or by endogenous pyrogen is suppressed in the ewe for a period extending from 2 to 5 d prepartum to several hours postpartum.

On the theory of elssticity of a nonhomogeneous medium

Abstract: In this paper the equation of equilibrium for a nonhomogeneous isotropic elastic solid under shear has been solved in rectangular Cartesian coordinates as well as in cylindrical polar coordinates. The modulus of rigidity of the material is assumed to vary in lateral as well as vertical directions. As an example, the above solution has been used to solve the problem of a Griffith crack in an infinite solid under shear.

Simultaneous measurements of energetic protons and electrons in the distant magnetosheath, magnetotail, and upstream in the solar wind

Abstract: The paper investigates the presence of energetic protons and electrons in the magnetopause/magnetosheath region of the tail as well as upstream from the bow shock in the solar wind, estimates the energy densities of protons and electrons, and assesses the relationship between the energies associated with these particles and the dayside reconnection region. The study is based on measurements in experiments on the IMP 7 and 8 spacecraft. It is shown that the energetic protons and electrons are present not only in the distant magnetosheath but also in the upstream solar wind and inside the magnetosphere. These protons carry much more energy (x50) than the electrons, and most likely originate inside the magnetosphere. Thus there appears to be little connection between the presence of these energetic particles in the distant magnetosheath region and the dayside reconnection region.

Mental rotation validation of two spatial ability tests.

Abstract: Three tests of spatial ability — speeded mental rotation and the Card Rotation and Revised Minnesota Form Board Tests — were examined with 32 college students. The slope of the linear function relating response time to angle of rotation in the mental rotation task was stimulus-dependent, increasing with stimulus symmetry. Males strongly dominated females on the Card Rotation Test and in speed of mental rotation, but not on the Minnesota Form Board Test or in the intercept of the judgment-time by angle-of-rotation plot. Practice with the simple forms used in the mental rotation task substantially improved scores with the many more complex forms used in the Card Rotation Test, but did not improve scores on the Minnesota Form Board Test. These results are not due to speed-accuracy tradeoff strategy differences. They suggest that “spatial ability” is not unitary and that test-based sex differences in spatial ability largely reflect differences in rotation speed or in a factor underlying rotation speed.

The Structural and Functional Roles of Metal Ions in Thermolysin

Abstract: (1978). The Structural and Functional Roles of Metal Ions in Thermolysin. CRC Critical Reviews in Biochemistry: Vol. 5, No. 1, pp. 1-23.