Showing papers by "University of Waterloo published in 1968"
TL;DR: In this article, it is shown that it is possible to estimate the annual production of stream benthic animals from data obtained from a series of good quantitative samples collected at intervals during the year.
Abstract: It is possible to calculate the annual production of stream benthic animals from data obtained from a series of good quantitative samples collected at intervals during the year. The method is explained and its limitations and shortcomings are discussed. This seems at present to be the only simple and direct method of estimating production.
353 citations
TL;DR: In this article, a solute-clustering model is proposed for grain boundary quench-hardening based on preferential solutevacancy interactions and non-ideal thermodynamic behavior of the binary system.
226 citations
TL;DR: In this paper, a special permeation cell was designed in order to study permeation rates at different temperatures ranging from 25 to 45°C, and it was found that the temperature dependence of the permeation rate for both pure compounds and mixtures could be expressed by Arrheniustype relationships.
Abstract: The permeation characteristics and the separation behavior of 25 combinations of binary liquid mixtures through low-density polyethylene membrane have been investigated. The organic compounds studied were members of the homologous series of liquid aliphatic hydrocarbons between n-pentane and n-nonane as well as some aromatic and cyclic compounds. A special permeation cell was designed in order to study permeation rates at different temperatures ranging from 25 to 45°C. The rate of permeation increased with temperature, and it was found that the temperature dependence of the permeation rate for both pure compounds and mixtures could be expressed by Arrheniustype relationships. The efficiency of separation, however, decreased with increasing temperature. Activation energies of permeation ranged from 16–22 kcal/mol for pure compounds and binary mixtures of benzene, n-hexane, cyclohexane, and 2–2-dimethylbutane. The effects of chemical nature, molecular size, and molecular shape of the diffusing species on the permeation and separation were studied and qualitative guidelines were suggested. The effect of the composition of the binary mixtures on the permeation rate has been investigated for several systems. Permeation enhancement effects were observed in which the mixtures permeate considerably faster than either of the pure components. Maximum permeation rates occurred at about 50 wt-% mixtures for the systems benzene–n-hexane and benzene–cyclohexane. This phenomenon is explained in terms of a combined internal plasticizing and solubility effect.
141 citations
TL;DR: A highly reliable time sampling assessment technique, which dichotomized classroom behavior into appropriate and inappropriate categories, was used to assess classroom behavior of institutionalized female adolescent offenders.
113 citations
TL;DR: In this article, one can obtain one-step methods of arbitrarily high order which satisfy Dahlquist's requirements of a-stability, and the authors show how to obtain one step methods of arbitrary high order that satisfy these requirements.
Abstract: The following note shows how one can obtain one step methods of arbitrarily high order which satisfy Dahlquist's requirements ofA-stability. Although most of these methods appear at the moment to be largely of theoretical interest the author is working on several practical applications.
110 citations
TL;DR: In this paper, the role of junction asymmetry in determining the I-V characteristics of the junction is found to be enhanced by the capture asymmetry of donor-like (acceptor-like) recombination centers in an n + - p (p + - n ) junction, but diminished in a p + − n (n + − p ) junction.
Abstract: The theory of generation-recombination in the space-charge region of a symmetrical p - n junction by Sah, Noyce and Shockley is extended to an asymmetrical junction. The role of junction asymmetry in determining the I–V characteristics of the junction is found to be enhanced by the capture asymmetry of donor-like (acceptor-like) recombination centers in an n + - p ( p + - n ) junction, but diminished in a p + - n ( n + - p ) junction. Where asymmetry effects are dominant at forward bias, the generation-recombination current is nearly independent of junction voltage, in contrast to the familiar exp( qV 2kT ) dependence predicted by the theory of Sah et al. Based on the presence of donor-like centers in an n + - p junction, a detailed discussion is given of the effects on the I–V characteristics at small forward bias due to variations in junction asymmetry, the capture asymmetry and energy level of the recombination centers. The theory is applied to InSb diodes, and previous analyses of generation-recombination current data on InSb diodes are examined.
107 citations
TL;DR: In this paper, a counting procedure for simple quadrangulations and a one-to-one correspondence between simple quadrangles and c-nets was established, and the enumeration of c-net with i+1 vertices and j+1 faces was performed.
104 citations
TL;DR: Artificial commutation with series capacitors, to extend the operation of mercury tube or solid-state converters beyond the normally attainable control angles, is analyzed in detail, and performance assessed for application to HVDC transmission as mentioned in this paper.
Abstract: Artificial commutation with series capacitors, to extend the operation of mercury tube or solid-state converters beyond the normally attainable control angles, is analyzed in detail, and performance assessed for application to HVDC transmission. Operating characteristics are presented, including details of tube voltage stress and attainable range of control for particular capacitor values and system quantities. The repercussions of arc-back and commutation failure are discussed, and control requirements outlined.
74 citations
TL;DR: Phial ides and two methods by which they may proliferate are described and described and species described and illustrated from New Zealand include two of Menispora, M. ciliata Corda and M. assamica.
Abstract: Summary Some brief remarks are made about phial ides and two methods by which they may proliferate. Generic descriptions are given for Menispora Pers. and Codinaea Maire. Although the type material of C. aristata, the type species of Codinaea, has not been seen, the generic name is considered to be an earlier synonym of Menisporella Agnthothrudu. The type species of Menisporella, M. assamica, is illustrated and redescribed from the type. Species described and illustrated from New Zealand include two of Menispora, M. ciliata Corda and M. uncinata n. sp., and 12 of Codinaea, C. botulispora n. sp., C. brevisetula n. sp., C. fertilis n. sp., C. longispora n. sp., C. obesispora n. sp., C. parva n. sp., C. setosa n. sp., C. simplex n. sp., and C. vulgaris n. sp., together with the perithecial and Codinaea states of Chaetosphaeria callimorpha (Mont.) Sacc., C. dingleyae Hughes, Kendrick and Shoemaker n. sp. and C. pulchriseta Hugh., Kendr., and Shoem. n. sp. Chaetosphaeria talbotii Hugh., Kendr., and Shoem. n. s...
69 citations
TL;DR: In this paper, the contributions of long-range triple-dipole three-body interactions to the thermodynamic properties of dense gaseous argon are calculated using a recently developed perturbation theory together with an accurately determined pair potential function.
Abstract: The contributions of long-range triple-dipole three-body interactions to the thermodynamic properties of dense gaseous argon are calculated using a recently developed perturbation theory together with an accurately determined pair potential function. Calculated pressures, internal energies, and critical constants are in reasonable agreement with experiment provided that the three-body contributions are included. The validity of the principle of corresponding states in the presence of three-body forces is discussed.
63 citations
TL;DR: In this paper, it is shown that the ordered set of quotient objects of a given object satisfies the Jordan-Dedekind chain condition and, as a further application, a proof of a result due to Edmonds (4) is given (Theorem III below).
TL;DR: In this article, the edges of a complete graph on 16 vertices are colored with three colors in such a way that no unicolored triangles are formed, and it is shown that these are the only colors possible.
TL;DR: In this paper, the effect of unbalances in the altemating voltages and the valve firing angles on the ac waveform was analyzed for six and 12-pulse dc conversion.
Abstract: Unbalance in the operation of high-voltage dc convertors gives rise to unusual or uncharacteristic harmonics in the ac waveform not expected from the existing theory relating to balanced operation. Analysis of the effect of unbalances in the altemating voltages and the valve firing angles is provided together with selected characteristics illustrating the variations in the harmonics with unbalance as determined by a comprehensive digital computer program. Six-pulse and 12-pulse operation is considered.
TL;DR: This work wanted to investigate conidium ontogeny by means of time-lapse photomicrography, and needed a culture chamber that fulfilled the following requirements: it would support growth and sporulation of the fungus over a period of several days without drying out or staling, and it could remain exposed on the stage of the microscope repeatedly and for long periods, without becoming contaminated.
Abstract: The construction and use of a thin culture chamber for time-lapse photomicrography of fungi at high magnifications are described. A photomicrographic sequence of blastospore development illustrates...
TL;DR: The near-reciprocal relationship between the depletion of Fractions 3 and the accumulation of Fraction 4 in the blood of milk-fed females reflects the disappearance of larval fat body and formation of adult fat body, the respective sources of these blood proteins.
TL;DR: In this paper, the effect of such variables as size of basis set, number of S and P type functions in the basis set and size of initial exponent in the base set, size of multiplicative factor in the geometrical progression of exponents, and interatomic distance has been examined by a self-consistent field calculation with Gaussian orbitals on HeH+.
Abstract: The effect of such variables as size of basis set, number of S and P type functions in the basis set, size of initial exponent in the basis set, size of multiplicative factor in the geometrical progression of exponents, and interatomic distance has been examined by a self-consistent-field calculation with Gaussian orbitals on HeH+. A quasi-optimized wave function has been obtained by allowing only the initial exponent and multiplicative factor to vary in the optimization process.
TL;DR: In this paper, the stability of symmetric structural systems with first and second order imperfections is investigated, and the analysis concerns a discrete system with n degrees of freedom, and expressions relating reduction in critical load to the magnitude of the imperfections indicate that a complex interaction exists between these quantities.
TL;DR: A theoretical analysis of the process of tube expanding by electromagnetic forces indicates that time-varying tube inductance, circuit resistance and the irreversible plastic work done on the tube are significant parameters of the performance of the electromagnetic forming machine.
TL;DR: In this article, the authors show that the rate of growth of fatigue cracks in polymethylmethacrylate is constant if the range of crack-tip stress-intensity factored in.
Abstract: Repeated tension tests on centre-notched sheet specimens show that the rate of growth of fatigue cracks in polymethylmethacrylate is constant if the range of crack-tip stress-intensity fact...
TL;DR: The cube law as discussed by the authors is an attempt to establish a formal mathematical relationship between the party's share of popular vote and its share of the seats in the legislature, and it was examined in detail by Kendall and Stuart in 1950, and later by Butler.
Abstract: The cube law is an attempt to establish a formal mathematical relationship between the party's share of the popular vote and its share of the seats in the legislature. First formulated by James Parker Smith in evidence before the Royal Commission on Systems of Election in 1910, it was examined in detail by Kendall and Stuart in 1950, and later by Butler.' Its purpose is to refute the criticism that the results of elections under simple-majority voting systems will be random or haphazard and that the relationship between seats and votes is totally unpredictable. In a system in which two parties (A1 and A2) dominate, the cube law can be expressed by the formula:
TL;DR: In this paper, the valence atomic orbitals (VAO's) of linear nitriles are determined using non-empirical SCF-LCAO-MO wave functions expanded in a minimal (CN−, HCN, FCN, C2N2), double-zeta (CN −, HN), or double-Zeta + polarization (HCN) basis of Slater atomic orbital (AO's).
Abstract: The valence atomic orbitals (VAO's) of several linear nitriles are determined using non-empirical SCF–LCAO–MO wave functions expanded in a minimal (CN−, HCN, FCN, C2N2), double-zeta (CN−, HCN), or double-zeta + polarization (HCN) basis of Slater atomic orbitals (AO's). The molecular energy of each system (except the double-zeta + polarization HCN system) is partitioned according to the procedure of Ruedenberg to obtain numerical values of nitrile C and N atomic and CN bond components of the energy. In addition, the nitrile results are compared with minimal AO basis results obtained previously by other authors for homonuclear diatomics, diatomic hydrides and H2O. The numerical data are used to test the internal self-consistency of the various definitions entering the partitioning method, i.e. whether or not analogous quantities assume similar values in chemically similar situations.
The analysis of nitrile SCF–MO wave functions in terms of the set of VAO's characteristic of the system under consideration is shown to be a promising approach to the problem of extracting useful information from the wave functions. In general, numerical results for the nitrile systems studied are fairly consistent with the concepts on which the partitioning method is based: promotion, quasi-classical interaction, sharing penetration, sharing interference and charge transfer. However, the VAO expansions for several energy components need to be investigated further and possibly revised.
TL;DR: In this paper, a two anatomically disparate, antagonistic, systems modulate the reinforcement potential of saline intake, one system provides positive feedback and the other, negative feedback to saline intake.
TL;DR: In the counterexample leading to s tatement 4, ~ is not on to ; in that leading to S ta tement 6, is not one-one as mentioned in this paper.
Abstract: In the counterexample leading to s tatement 4, ~ is not on to ; in that leading to s ta tement 6, ~ is not one-one. Two interesting questions, not covered by the above theorems and statements, are these. (i) I f n is Pappian, and if ~ is a one-one col l ineat ion from Q onto Q', can necessarily be embedded in a coll ineation from n onto n '? If so, can the Pappian condi t ion be weakened? (ii) Is it possible to weaken the condi t ion in theorem 4 that n be a Moufang plane, and to assume only that n satisfies condi t ion (ii) of theorem 3?
TL;DR: Differences in walking patterns of 18 pecoran species belonging to four families are discussed with respect to anatomy and environment and variation in the walk patterns of members within a species is assessed.
Abstract: A method is presented for defining the walking gaits of quadrupeds from films so that they can be compared in closely related species. Differences in walking patterns of 18 pecoran species belonging to four families are discussed with respect to anatomy and environment. Variation in the walk patterns of members within a species are assessed. They are found to vary often with the speed at which the walk is executed, with the terrain, with the presence of heavy horns or antlers and with age. The time taken for one walking stride increases with the increase in length of the legs, but the legs swing forward more rapidly than they would if they acted passively like cylindrical pendulums.
TL;DR: The tradition of maintaining an appropriate racial, religious, and regional balance in the federal cabinet of Canada was introduced by Macdonald's first national ministry in 1867 and has now become a tradition of government in this country from which no prime minister can easily depart as discussed by the authors.
Abstract: The source of all that is unique in the Canadian political system is generally to be found in the practice of Sir John Macdonald. Perhaps the most striking example of his influence is the unwritten rule which requires that an appropriate racial, religious, and regional balance be maintained in the federal cabinet: a practice which began with the formation of Macdonald's first national ministry in 1867 and which has now become a tradition of government in this country from which no prime minister can easily depart.' It is claimed that this arrangement is essential for the effective exercise of national power in Canada because, as Andr6 Siegfried observed at the turn of the century, the different elements of our population are too deeply divided to be allowed to compete with each other openly.
TL;DR: The effect of a cigarette on the heart rate of habitual smokers was assessed after brief abstinence and after regular smoking, with controls of sham smoking and deep breathing.
Abstract: The effect of a cigarette on the heart rate (HR) of habitual smokers was assessed after brief abstinence and after regular smoking, with controls of sham smoking and deep breathing. Smoking, and only smoking, caused elevations in HR of about 20 bpm. The effect mimics habituation, and its dissipation, which may take about an hour, proceeds more slowly after continual smoking than after smoking a single cigarette after a few hours abstinence.