Showing papers by "University of Alberta published in 1969"

The distribution of cacao cultivation in pre‐columbian america1

Abstract: On the eve of the Spanish conquest aboriginal cacao cultivation extended from the two coasts of central Mexico to Costa Rica. Although the districts of greatest production were located within the Maya language areas of southern Mexico and Pacific Guatemala-El Salvador, a large and increasing market for cacao lay in the Nahua language areas of highland Mexico. To this area important amounts of cacao moved in trade from the southern zone of production. Distributions of Indian cacao cultivation have been plotted from published and unpublished primary sources. An unpublished tribute assessment list (Tasacion de Tributos 1548–51) provides the most detailed distributional information available for the significant cacao zones of Guatemala and El Salvador.

Rotation Capacity of Beams under Moment Gradient

Abstract: This investigation attempts to relate the flange slenderness ratio to the rotation capacity of steel wide-flange beams subjected to a moment gradient. The steel used was CSA G 40.12, a low alloy steel having a specified minimum yield stress of 44 ksi. The reported tests were performed on simply-supported beams, subjected to a concentrated load at midspan. The flange and web geometry were varied, while the laterally unbraced slenderness ratio was held constant. All tests were continued until substantial unloading had occurred due to the effects of instability. In all cases rotation capacity was terminated by local buckling of the compression flange accompanied by large lateral deformations of the unbraced span. For beams under high moment gradient the length of the local buckle was restricted by the extent of yielding, while for beams under lower moment gradient the local buckle occupied only part of the yielded length.

Finite-Element Large Deflection Analysis of Plates

Abstract: A finite element formulation for the analysis of thin elastic plates subjected to transverse loading and including nonlinear geometric effects associated with large deflections is presented. The analysis utilizes local co-ordinate axes which translate and rotate with the individual elements so that the small deflection Kirchhoff formulation remains valid, with respect to these axes, and may be applied to determine element stiffness and resisting forces. Nonlinear terms in the strain displacement equations are included in the coordinate transformation and change of plate configuration is included in the equilibrium equations. The formulation is applied, using an iterative technique and an approximate incremental stiffness, to obtain solutions to a number of typical large deflection plate problems. Results include an inextensional plate problem, cylindrical bending, and a square plate with simple edge condition. Deflection and stress results are compared with solutions available in the literature.

Nurturing Cultural Diversity in Higher Education: A Critical Review of Selected Models

Abstract: Canadian universities and colleges are becoming increasingly ethnoculturally diverse. Two major social forces have contributed to this change: immigration and increasing enrolment of international students. Minority and international students bring their values, language, culture and educational background to our campuses, to add to and enrich our educational environments. To build an inclusive education, we have the ethical and educational responsibility to embrace such difference and diversity and to integrate it into all aspects of university life, including teaching and learning. However, in our daily encounter with cultural diversity we still confront many challenges, such as the colourblind and the “difference as defi cit” perspectives, partially resulting from a lack of knowledge and readiness to approach diversity. The goal of this article is to bridge this gap by examining three selected models commonly used to nurture cultural diversity in higher education: the intercultural education model, the multicultural education model, and the anti-racist education model. It is hoped that this discussion will benefi t the university community in Canada as well as in other countries where diversity prevails. Du fait de l’immigration et de l’augmentation du nombre d’etudiantes et d’etudiants internationaux, les universites et colleges du Canada sont de plus en plus diversifi es sur le plan ethnoculturel. Les etudiantes et etudiants issus des minorites ethniques ainsi que d’autres pays apportent avec eux leurs valeurs, langues et cultures, ce qui enrichit d’autant le milieu educatif. Il est de notre responsabilite a la fois morale et educative, si nous voulons creer un environnement inclusif, d’integrer ces differences et cette diversite dans tous les aspects de la vie universitaire, y compris l’enseignement et l’apprentissage. Toutefois, dans nos rencontres quotidiennes avec la diversite culturelle, nous sommes confrontes a plusieurs defi s, notamment les modeles dits « aveugles a la couleur » et la perception de « la difference comme defi cit ». Ces perspectives resultent en partie d’un manque de connaissances et d’attitudes peu disposees a accueillir la diversite culturelle. Le but de cet article est de repondre a ces defi s en examinant trois modeles frequemment employes pour encourager la diversite culturelle dans l’enseignement superieur : l’education interculturelle, l’education multiculturelle et l’education anti-raciste. Nous esperons que cette discussion aura des effets positifs pour la communaute universitaire du Canada et d’autres pays marques par la diversite.

An Investigation of the Origin of Stable Remanence in Magnetite-bearing Igneous Rocks

Abstract: Experiments designed to elucidate the nature and source of high-stability remanence in igneous rocks have been carried out. Many of the pyroxene grains of the samples used (from the Modipe gabbro of southern Africa) contain small (from a few microns down to the optical limit) magnetite inclusions, some of which are very probably single-domained by virtue of their size and shape. It is shown that these inclusions contribute significantly to the TRM, and may, in fact, account for virtually all of the remanence. Measured coercivities as high as 1800 œ are attributed to the observed shape anisotropy of some of the magnetite inclusions. A discussion of the various theories of coercive force indicates that this is the only mechanism which enables magnetite to possess coercivities in excess of 1000 oersteds.The conclusions reached can be strictly applied only to this particular rock; however, it is felt that the natural occurrence of single-domained magnetite is more common than previously supposed. The reason for the comparative rarity of similar observations may well be the minute size and very small total quantity of magnetite necessary to account for typical TRM's in igneous rocks.

Thermal Ion–Molecule Reaction Rate Constants at Pressures up to 10 torr with a Pulsed Mass Spectrometer. Reactions in Methane, Krypton, and Oxygen

Abstract: A mass spectrometer for high‐pressure ion–molecule reaction studies was constructed using a pulsed 4‐keV electron beam and pulsed “gate‐open” mass‐spectrometer detection. The ions drift out of the field‐free ion source by diffusion and mass flow. Pressures up to 10 torr can be used and the ion reaction times can be as long as several hundred microseconds. The system is specially suited for study of reactions with very small rate constants, long reaction sequences, and reactions dependent on third‐body deactivation. Also when reverse reactions are operative the establishment of the equilibrium can be directly followed. The thermal rate constants for the reactions of Kr+ with CH4, and CH4+ and CH3+ with CH4, were measured. The reaction of O2+ with O2 to form O4+ is found to be third order, proceeding with a rate constant K = 2.8 × 10−30cm6molecules−2·sec−1 at 298°K. The activation energy for the reaction is negative and equal to 1–2 kcal/mole. The equilibrium constants for the reaction O2+ + 202⇄O4 + +O2 we...

Influence of Glucose on the Transmembrane Action Potential of Papillary Muscle : Effects of concentration, phlorizin and insulin, nonmetabolizable sugars, and stimulators of glycolysis

Abstract: The action potential duration (APD) of isolated guinea pig papillary muscle is directly related to the medium glucose concentration regardless of the gas mixture with which it is in equilibrium. The APD can be maintained at control value for many hours by a glucose concentration of 50 mM in the complete absence of oxygen. Following reduction of the APD by incubation of the muscle in medium containing 5 mM glucose, adjustment of the glucose concentration to 50 mM will cause restoration of normal APD. Phlorizin has been shown to competitively interfere with the effect of glucose on the APD and insulin to prevent or reverse the effect of phlorizin. Nonmetabolizable sugars cannot produce glucose-like effects on the APD. Adrenaline, noradrenaline, and isopropylnoradrenaline increased the reduced APD of papillary muscles incubated in the absence of oxygen in a medium containing 5 mM glucose coincident with an increase in contractile force. The effect of isopropylnoradrenaline was blocked by acetylcholine and propranolol. In the presence of iodoacetate and 2-deoxyglucose, isopropylnoradrenaline increased contractile force but not the reduced APD. Aminophylline was found to produce changes in the reduced APD similar to those caused by the sympathomimetic amines. The findings clearly support the hypothesis that anaerobic metabolism utilizing either glycogen or exogenous glucose is capable of maintaining normal transmembrane electrical activity in guinea pig papillary muscle.

Finite-Element Postbuckling Analysis of Thin Elastic Plates

Abstract: reflects the Fourier stiffness distribution profile (A convergence trend is exhibited because the higher-order harmonics of the solution diminish in magnitude) The total deflection obtained by summing the Fourier contributions is plotted along the plane of symmetry (6 = 0-180°) in Fig 5 Also shown are the deflections obtained for axisymmetric shells with uniform stiffness distributions corresponding to the magnitude of the stiff and weak sides As expected, these results bracket the solution for the variable-rigidity shell The same problem was a run with only three and five terms retained in the stiffness series expansions Variation in the third harmonic of deflection (w%) along the meridian is plotted in Fig 6 for the cases where K is set equal to 3, 5, and 10 The higher harmonic coupling effects appear to diminish as more terms are retained in the solution (ie, as K increases) For economic purposes, the number of integration points used in obtaining the preceding numerical results was N = 26 The basic character of the solutions is illustrated for the relatively coarse grid Additional studies have shown increased accuracy when a finer finite-difference mesh is taken; this should be considered when the results presented in this paper are interpreted

Inelastic Electron Tunneling in Al-Al-Oxide-Metal Systems

Abstract: A systematic study of inelastic electron tunneling in Al-Al-oxide-metal thin-film junctions in the bias range 30-500 mV has been made. Most measurements were performed on twin junctions made by evaporating two different metal films across the same oxidized Al base film. The experimental results of this paper can be divided into three groups. The first of these is a reidentification of some vibrational bands that appear in the tunneling spectra of Al-oxide systems. A prominent peak that appears between 115 and 120 mV in these spectra has been identified as being due to a vibrational mode of an alumina hydrate. In addition, a new OH mode has been found at about 75 mV in these systems. The experimental results that constitute the second group are the effects on the tunneling spectra of Al-Al-oxide systems due to the metal used as the top electrode. By studying the twin junctions described above, it has been found that the intensity of vibrational bands due to molecular impurities relative to the intensity of vibrational bands due to oxide modes is correlated with the ionic radius of the metal used as the top electrode. This correlation is interpreted as being caused by a size-dependent penetration of the top electrode into the oxide layer of the junction. The last group of experimental results involves changes in tunneling spectra of Al-Pb junctions produced by applying a DC potential across the samples at room temperature. These changes are interpreted as being due to the movement of dissolved gases in the Pb electrode of the junctions.

A self-disclosure inventory for adolescents.

Abstract: The development of a self-disclosure inventory designed for use with adolescents is described. The inventory yields a grand disclosure score, 6 aspect-disclosure subscores, and 6 disclosure-to-targ...

Life-cycles of helminth parasites using Gammarus lacustris as an intermediate host in a Canadian lake.

Abstract: The systematics and life-cycles of the helminths of a local population of Gammarus lacustris in a eutrophic lake near Edmonton, Alberta, is reported as part of a larger study of the composition and seasonal dynamics of the helminth fauna of gammarids.A total of 12 species of helminths, including eight cestodes, one nematode and three acanthocephalans, were recovered. Of these, eleven were new host records, ten were assigned to an intermediate host species for the first time, and one, Hymenolepis albertensis sp.nov., was described for the first time.Adults of all twelve helminths were raised in experimentally infested birds and the life-cycles of five species (Lateriporus clerci, L. skrjabini, Hymenolepis albertensis sp.nov., Fimbriaria fasciolaris and Polymorphus marilis) were completed in the laboratory. The larvae are described, and the developmental period in the gammarids, prepatent period and life span of the adults are given for many of the helminths.The rate of development of the cysticercoids of Lateriporus skrjabini was shown to be directly related to the size of the gammarid and inversely related to the intensity of infestation.The proboscis-hook formula was not a good diagnostic character for the separation of the three acanthocephalans, Polymorphus contortus, P. marilis and P. paradoxus; however, the size of the largest hook and the structure of the cystacanth body-wall were good diagnostic characters.I am indebted to Dr J. C. Holmes for advice and encouragement at all stages of the study. I also wish to thank Drs S. Prudhoe and D. R. R. Burt for their editorial assistance, Mr L. Graham for many helpful suggestions and information on the natural definitive hosts of the species encountered, Mr R. Podesta for his laboratory assistance, and Miss E. D. Senio for caring for the ducklings during their first few days of life. The study was supported by the Francis F. Reeve Foundation Graduate Bursary, the Queen Elizabeth Education Scholarship Fund, by the Department of Zoology through a Teaching Assistantship, by a grant from the R. B. Miller Biological Station Fund and by an N.R.C. operating grant (A–1464) to Dr J. C. Holmes.

Assimilation of labelled glucose from seawater by marine nematodes

Abstract: RECENTLY there has been much interest in the ability of marine invertebrates to assimilate dissolved organic molecules. It has been shown that, with the notable exception of some arthropods, representatives of most phyla can freely absorb amino-acids and simple sugars through the body wall and subsequently assimilate them into macromolecules1–3. All the experimental work to date, however, has been conducted on macrobenthic animals, although the meiobenthos would probably benefit most from this food source in view of their large surface area/volume ratio. Nematodes are among the commonest meiobenthic animals and, in spite of the fact that their thick cuticle might be expected to preclude absorption in rather the same way as the exoskeleton of arthropods, it was decided to test them for possible uptake. Glucose was considered to be a likely substance for assimilation because the main energy store in nematodes is glycogen4, and concentrations of 10−6–<10−8 glucose are known to be present in seawater5. The nematode chosen for the experiment was the oncholaimid Pontonema vulgare (Bastian) because it is large, easily identifiable, and can be readily obtained from Laminaria holdfasts on the rocks below the Dove Marine Laboratory in Northumberland.

Boundary shear stress distribution in rectangular open channels

Abstract: (1969). Boundary shear stress distribution in rectangular open channels. La Houille Blanche: Vol. 55, No. 6, pp. 603-610.

Influence of Glucose on the Transmembrane Action Potential of Guinea-Pig Papillary Muscle: Metabolic Inhibitors, Ouabain, and Calcium Chloride, and their Interaction with Glucose, Sympathomimetic Amines, and Aminophylline

Abstract: In a previous report, we have proposed that anaerobic glycolysis alone can maintain an action potential of normal duration in guinea-pig papillary muscle. This proposal followed from the observation that 50 mM glucose, several sympathomimetic amines, and aminophylline all caused the duration of the action potential of muscles, which had been reduced by incubation in a medium containing 5 mM glucose, to return toward control values. This occurred in the presence or absence of oxygen. It was further proposed that the ATP resulting from anaerobic glycolysis was in some way preferentially utilized in the membrane by a process controlling repolarization and therefore the duration of the action potential. The present experiments were undertaken to determine what metabolic pathways were necessary for the glucose effect mentioned above, by the use of the metabolic inhibitors sodium cyanide, iodoacetic acid, and 2,4-dinitrophenol. Secondly, the effects of ouabain and calcium, which are known to modulate the utilization of ATP, on the glucose effect were studied. It was concluded that an intact glycolytic pathway is necessary for the effect of glucose on the electrical activity of papillary muscle and that the effect can be increased or decreased by low or high doses of ouabain, respectively. The actions of ouabain are thought to be due to a stimulation and depression of a membrane ATP-ase.