Showing papers by "University of Alberta published in 1977"
TL;DR: The authors Linking Ways of Knowing with Ways of Being Practical: Curriculum Inquiry: Vol. 6, No. 3, pp. 205-228, The authors, discusses the relationship between the ways of knowing and being practical.
Abstract: (1977). Linking Ways of Knowing with Ways of Being Practical. Curriculum Inquiry: Vol. 6, No. 3, pp. 205-228.
1,599 citations
1,499 citations
TL;DR: In this article, a stress state variable for an unsaturated soil is proposed on the basis of writing force equilibrium equations for each phase, within the context of multiphase continuum mechanics.
Abstract: An unsaturated soil is visualized as a four-phase system, the fourth phase being the air-water interface commonly referred to as the contractile skin. Suitable stress state variables for an unsaturated soil are proposed on the basis of writing force equilibrium equations for each phase, within the context of multiphase continuum mechanics. The analysis indicates that any two of three possible normal stress variables can be used to define the stress state. Experimental null-type tests verified the proposed stress state variables for the soil structure and contractile skin of an unsaturated soil.
749 citations
01 Sep 1977
484 citations
TL;DR: The variations of the D/H and (18)O/(16)O ratios of nonexchangeable hydrogen and oxygen in plant cellulose reveal systematic differences between terrestrial plant groups.
Abstract: The variations of the D/H and (18)O/(16)O ratios of nonexchangeable hydrogen and oxygen in plant cellulose reveal systematic differences between terrestrial plant groups. The slope of deltaD versus delta(18)O of cellulose from a variety of aquatic plants is close to 8 (the meteoric water value), while the slope for a number of terrestrial species is greater than or equal to about 24. Two models involving incorporation of CO(2) and H(2)O into cellulose precursors are proposed to account for these differences. Effects of evaporative transpiration on the isotopic composition of water in leaves are measured and discussed in the context of these models.
349 citations
TL;DR: It is proposed that subsequent association of the membrane-bound aminoglycoside with higher-affinity binding sites on membrane-associated ribosomes carrying out a normal ribosomal cycle and protein synthesis results in a more rapid transport rate (termed energy-dependent phase II).
Abstract: Several mutants of Escherichia coli affecting aerobic energy generation and energization of the bacterial membrane have been examined for their effect on streptomycin and gentamicin accumulation and susceptibility. A heme-deficient mutant (K207) and two mutants (CJ-8 [colicin K insensitive] and NR-70) associated with defective aerobic active transport were associated with decreased transport of streptomycin and gentamicin and increased resistance to those antibiotics. These mutants also exhibited increased resistance to several other aminoglycoside antibiotics, but not the aminocyclitol spectinomycin. The same observations were made with a ubiquinone-deficient mutant, but a strA derivative of this mutant was shown additionally to be saturable for streptomycin accumulation at a concentration four or more times lower than that required for saturation of the parent. A mutant uncoupled for adenosine 5′-triphosphate synthesis from electron transport and membrane Mg-adenosine 5′-triphosphatase deficient was hypersensitive to those aminoglycosides tested and spectinomycin, and showed enhanced transport of streptomycin and gentamicin. A variety of compounds structurally related to streptomycin were examined at high concentrations for inhibition of streptomycin uptake in a strA mutant of E. coli K-12 SA 1306, but no evidence for competition was detected, suggesting the absence of a common transport carrier. Four different divalent cations were shown to inhibit streptomycin and gentamicin accumulation in E. coli K-12 SA 1306. Divalent cations were shown to inhibit uptake of these two drugs in two bacterial species with distinct cell wall structures, Pseudomonas aeruginosa and Staphylococcus aureus , and to inhibit streptomycin uptake in spheroplasts of streptomycin-susceptible and -resistant E. coli . However, calcium had almost no inhibitory effect on streptomycin uptake by the ubiquinone-deficient mutant E. coli AN66. These and previous findings have been used to formulate a model for aminoglycoside entry into bacteria using a low-affinity membranous complex involved in membrane energization that includes respiratory quinones, which probably act to bind and transport aminoglycosides across the cell membrane. This phase of transport is associated with the lowest accumulation rate (termed energy-dependent phase I) that is rate limiting for susceptibility. It is further proposed that subsequent association of the membrane-bound aminoglycoside with higher-affinity binding sites on membrane-associated ribosomes carrying out a normal ribosomal cycle and protein synthesis results in a more rapid transport rate (termed energy-dependent phase II). The increased rate could result from a state of membrane energization analogous to that causing enhanced aminoglycoside transport rates seen in the uncoupled mutant, AN120. How this model explains the mechanism by which enzymatically modified aminoglycosides render cells resistant to unmodified aminoglycosides is also discussed.
258 citations
TL;DR: The results provide a possible rationale for the degradation of DNA which accompanies anthracycline administration as adriamycin, daunorubicin and both ring C reduced forms bind intercalatively and completely relax supercoiled DNA.
255 citations
TL;DR: It is shown that 2-Mercaptoethanol, dithiothreitol, ascorbic acid and xanthine/xanthine oxidase, hitherto commonly used with bleomycin studies, separately cleave DNA by a similar mechanism.
242 citations
TL;DR: In this article, a necessary step in the implementation for layered media displaying transverse isotropy is the computation of reflection and transmission coefficients at the interface between two such layers, as well as the corresponding surface conversion coefficients.
Abstract: It has become necessary in seismology to consider more complicated models of the Earth9s structure in order to obtain synthetic seismograms that are more consistent with actual field data. Gassmann (1964) and Postma (1955) have presented results dealing with travel-time methods in anisotropic media—in particular, transversely isotropic media. Kinematic properties alone, however, are not enough to conclusively interpret seismic records. Consequently, dynamic properties must be considered producing a need for synthetic seismograms. One of the most efficient methods for obtaining synthetic seismograms is through the use of asymptotic ray theory (Hron and Kanasewich, 1971; Hron, 1973; Hron, Kanasewich and Alpaslan, 1974). A necessary step in the implementation for layered media displaying transverse isotropy is the computation of reflection and transmission coefficients at the interface between two such layers. Reflection coefficients for a free interface and the corresponding surface conversion coefficients must be computed, as well. Theoretical formulas for reflection, transmission, and surface conversion coefficients corresponding to the zero-order approximation of asymptotic theory are presented for the above-mentioned media.
229 citations
229 citations
TL;DR: The preliminary results illustrate the hazards of heparin therapy and suggest that bleeding complications are more closely related to duration of therapy, age, sex, and surgical trauma than to method of administration.
TL;DR: In this paper, a general model for the persistence of all species in a three-level food chain is introduced and the equilibria analyzed, and boundedness and stability criteria are established.
Abstract: The paper is basically concerned with the question of persistence of all species in a three-level food chain. A general model is introduced and the equilibria analyzed. Boundedness and stability criteria are established. Three special cases of the model are analyzed, showing the applicability of the theory, and in certain cases extensions are given. The special cases include Lotka-Volterra (where we are able to give necessary and sufficient conditions for persistence), Lotka-Volterra predation with a carrying capacity at the lowest level, and a mixed Lotka-Volterra and Holling predation (at different levels) with a carrying capacity at the lowest level.
TL;DR: This review attempts to cover the important contributions which have been made in the fields of structural and synthetic chemistry as well as in the biosynthesis and mode of antimicrobial activity of the “polyoxo” macrolide antibiotics.
Abstract: The progress of macrolide chemistry and biochemistry over the past several years has indeed been remarkable. This review attempts to cover the important contributions which have been made in the fields of structural and synthetic chemistry as well as in the biosynthesis and mode of antimicrobial activity of the “polyoxo” macrolide antibiotics. Emphasis has been placed on the recent synthetic achievements in this field.
TL;DR: The level of ecdysone in Drosophila melanogaster was determined by a radioimmune assay in organisms selected between the second larval instar and maturity, suggesting a possible role for ecdYSone in ovarian maturation in this organism.
TL;DR: A procedure has been developed for the stable long-term recording of nerve signals in unanesthetized mammals, which should have wide application in basic research on the nervous system and also in clinical areas such as the derivation of control signals for powered prostheses.
TL;DR: Alignment of the amino acid sequence with that of pepsin shows regions of high homology.
Abstract: The polypeptide chain of the acid protease penicillopepsin folds via an 18-stranded mixed β-sheet into two distinct lobes separated by a 30-A long groove which is the extended substrate binding site. The catalytic residues Asp-32 and Asp-215 are located in this groove and their carboxyl groups are in intimate contact. Alignment of the amino acid sequence with that of pepsin shows regions of high homology.
TL;DR: In this paper, the rigorous critical state criterion enunciated by Willard Gibbs can be used with a recently formulated two-parameter equation of state to obtain an analytical solution to the problem of predicting the critical properties of defined multicomponent mixtures.
Abstract: This paper shows how the rigorous critical state criterion enunciated by Willard Gibbs can be used with a recently formulated two-parameter equation of state to obtain an analytical solution to the problem of predicting the critical properties of defined multicomponent mixtures. Comparisons are made between predicted and experimental values for several systems containing paraffin hydrocarbons and related materials.
TL;DR: Adenine nucleotides, probably acting via the common metabolite adenosine, inhibit adrenergic neurotransmission at a presynaptic site in rat vas deferens in vitro but had no effect on the responses to exogenous noradrenaline.
TL;DR: An analytical method involving computerized gas Chromatographic mass spectrometric "Multiple Ion Cross Scan" technique has been developed for the study of chemical transformations in the biodegradation of crude oils as discussed by the authors.
TL;DR: Carlson, A.A. et al. as mentioned in this paper discuss the possibility of quantifying scenic beauty in the natural environment from the point of view of philosophical aesthetics and bring out certain general themes which characterize this work and contribute to its overall approach.
TL;DR: Simplicial decomposition is a special version of the Dantzig—Wolfe decomposition principle, based on Carathéodory's theorem, which allows the direct application of any unrestricted optimization method in the master program to find constrained maximizers for it.
Abstract: Simplicial decomposition is a special version of the Dantzig—Wolfe decomposition principle, based on Caratheodory's theorem. The associated class of algorithms has the following features and advantages: The master and the subprogram are constructed without dual variables; the methods remain therefore well-defined for non-concave objective functions, and pseudo-concavity suffices for convergence to global maxima. The subprogram produces affinely independent sets of feasible generator points defining simplices, which the master program keeps minimal by dropping redundant generator points and finding maximizers in the relative interiors of the resulting subsimplices. The use of parallel subspaces allows the direct application of any unrestricted optimization method in the master program; thus the best unconstrained procedure for any type of objective function can be used to find constrained maximizers for it.
TL;DR: The convergence of the Zassenhaus formula has been proven under an appropriate condition for other exponential operators such as the Baker-Campbell-Hausdorff formula.
Abstract: The convergence of the Zassenhaus formula is proven under an appropriate condition as well as for other exponential operators such as the Baker-Campbell-Hausdorff formula.
TL;DR: The trace lengths of discontinuities from Nchanga Open Pit are a sample from a censored negative exponential distribution as discussed by the authors, and the largest trace length of a discontinuity in the distribution can be estimated from the parameters of the distribution and is substantially larger than an estimate by another method.
TL;DR: High concentrations of deoxycoformycin and EHNA inhibit all pathways of purine ribonucleotide synthesis, and inhibit the conversion of inosinate to adenine and guanine nucleotides.
01 Jan 1977
TL;DR: It was found that histoincompatible helper cells were able to help a cytotoxic T cell response to a third party stimulator cell antigen (H-2d), and it seems likely that the histocompatible helper cells induce killer precursors in an antigen-specific cooperation event similar or identical to normal syngeneic cooperation.
Abstract: Thymocytes cultured with irradiated, allogeneic stimulator cells yield no cytotoxic effector cells after a period in culture. If, however, a population of irradiated spleen cells syngeneic to the responder cells are added to these cultures, cytotoxicity is generated. The helper activity present in the irradiated syngeneic spleen cells was found to be mediated by a cell bearing theta antigens. Furthermore, it was found to be antigen specific; helper cells which were tolerant of the stimulator cell antigens were unable to help the thymocyte responder cells, although these tolerant cells did contain helpers specific for a third party antigen. These experiments are consistent with a requirement for associative recognition of linked determinants in the induction of killer precursors which is thus strictly analogous to the induction of B-cell precursors via collaboration with helper T cells. In more extensive studies, it was found that histoincompatible helper cells (H-2b, H-2p, H-2q) were able to help a cytotoxic T cell (H-2k) response to a third party stimulator cell antigen (H-2d); that is, the helper T cells which interact with cytotoxic T-cell precursors are not strain specific. It seems likely that the histocompatible helper cells induce killer precursors in an antigen-specific cooperation event similar or identical to normal syngeneic cooperation.
TL;DR: In this article, the authors present an experimental study on the erosion of loose beds of sand and polystyrene by circular turbulent wall jets ol" air and water Characteristics of the scour hole have been
Abstract: Summary This paper presents an experimental study on the erosion of loose beds of sand and polystyrene by circular turbulent wall jets ol" air and water Characteristics of the scour hole have been
TL;DR: This article found that bilingual education may even have a positive effect on some cognitive processes, suggesting that under certain learning conditions access to two languages can positively influence the development of some cognitive process.
Abstract: unilingually instructed counterparts and, in addition, would become anomic individuals without affiliation to either ethnolinguistic contact group. In contrast to these earlier beliefs regarding the negative effects of bilingual education, Stern (1973) notes that in recent years there has been an eagerness to make education in two languages much more widely available and to regard it as educationally desirable. Evaluations of many North American bilingual education programs lend support to this optimism. In general, programs designed to teach a second language to English speaking children have proved successful (Cohen, 1974; Swain, 1974) while immersion programs designed to teach English to non-English speaking children have been less successful. However, as Cohen (1975) points out these latter programs lack several ingredients which are highly desirable in immersion programs. The evaluation of the best known of recent Canadian bilingual education programs suggests the possibility that bilingual education may even have a positive effect on some cognitive processes. Children in the well-documented St. Lambert bilingual program in Montreal have shown no intellectual disadvantages in relation to the controls throughout the elementary school period and at some grade levels have performed at a significantly higher level than the controls on measures of divergent thinking (Bruck, Lambert and Tucker, 1973; Lambert, Tucker and d'Anglejan, 1973). This renewal of optimism in the efficacy of bilingual education has been paralleled by a reversal of the research evidence regarding the influence of bilingualism on cognition. Investigations of the relationship between bilingualism and cognition conducted prior to the Peal and Lambert study in 1962 generally found that bil guals performed at a lower level than unilinguals on measures of verbal intelligence (see reviews by Darcy, 1953; Jensen, 1962; Macnamara, 1966; Peal and Lambert, 1962). Peal and Lambert (1962) have criticized these early studies on the grounds that many of them failed o control for confounding variables such as socioeconomic status, sex and the bilingual's k owledge of his two languages. The results of the Peal and Lambert study and of subsequent investigations (Bain, 1974; Balkan, 1970; Ben Ze'ev, 1972; Cummins, 1976b; Cummins and Gulutsan, 1974a; Ianco-Worrall, 1972; Landry, 1974; Liedke and Nelson, 1968) indicate that under certain learning conditions access to two languages can positively influence the development of some cognitive processes. In several recent studies an association has
TL;DR: In this article, ultrasonic transmitters were implanted in the fishes' stomachs to monitor the movements of northern pike (Esox lucius) in Lac Ste. Anne, Alberta for 5 to 47 days.
Abstract: Movements of northern pike (Esox lucius) in Lac Ste. Anne, Alberta were monitored for 5 to 47 days using ultrasonic transmitters which were implanted in the fishes' stomachs. None of the nine fish studied established well-defined home ranges. The pike were usually found within 300 m of shore and in water less than 4 m deep. No major differences were found in the extent of movement or in habitat selection between summer and winter. Daily pike movements were from 0 to 4,000 m, but most daily movements were less than 1,000 m.