Showing papers by "University of Waterloo published in 1977"
01 Jan 1977
TL;DR: In the Hamadryas baboon, males are substantially larger than females, and a troop of baboons is subdivided into a number of ‘one-male groups’, consisting of one adult male and one or more females with their young.
Abstract: In the Hamadryas baboon, males are substantially larger than females. A troop of baboons is subdivided into a number of ‘one-male groups’, consisting of one adult male and one or more females with their young. The male prevents any of ‘his’ females from moving too far from him. Kummer (1971) performed the following experiment. Two males, A and B, previously unknown to each other, were placed in a large enclosure. Male A was free to move about the enclosure, but male B was shut in a small cage, from which he could observe A but not interfere. A female, unknown to both males, was then placed in the enclosure. Within 20 minutes male A had persuaded the female to accept his ownership. Male B was then released into the open enclosure. Instead of challenging male A , B avoided any contact, accepting A’s ownership.
2,364 citations
TL;DR: In this paper, the authors measured seepage velocities from −0.1-2.58 µm s−1 in Minnesota and Wisconsin lakes and in Nova Scotia and North Carolina estuaries.
Abstract: Seepage flux can be measured and samples of groundwater flowing into lakes and estuaries collected by enclosing an area of bottom with a cylinder vented to a plastic bag. The method has the advantage of not requiring measurements of permeability of bottom sediments. Seepage velocities from −0.1–2.58 µm s−1 were measured in Minnesota and Wisconsin lakes and in Nova Scotia and North Carolina estuaries.
Where seepage inflow was rapid (0.4–0.8 s−1), water collected with the seepage meter was chemically similar to water from wells on the same flow path, and the distribution and chemistry of the seepage concurred with a theoretical flow net. The rate and direction of seepage flux were correlated with water surface elevation during a tidal cycle.
739 citations
TL;DR: Factor analysis of the individual items revealed a primary handedness factor, and two factors that are idiosyncratic to the wording of the questions, which suggest shortened versions of the two tests are recommended.
738 citations
642 citations
TL;DR: In this article, the authors present an analysis of hourly diffuse radiation on a horizontal surface and recommend an equation to determine the hourly ratio of diffuse-to-total radiation received in a horizontal surfaces.
550 citations
TL;DR: The present state of the art of isomorphism testing is surveyed, its relationship to NP-completeness is discussed, and some of the difficulties inherent in this particularly elusive and challenging problem are indicated.
Abstract: The graph isomorphism problem—to devise a good algorithm for determining if two graphs are isomorphic—is of considerable practical importance, and is also of theoretical interest due to its relationship to the concept of NP-completeness. No efficient (i.e., polynomial-bound) algorithm for graph isomorphism is known, and it has been conjectured that no such algorithm can exist. Many papers on the subject have appeared, but progress has been slight; in fact, the intractable nature of the problem and the way that many graph theorists have been led to devote much time to it, recall those aspects of the four-color conjecture which prompted Harary to rechristen it the “four-color disease.” This paper surveys the present state of the art of isomorphism testing, discusses its relationship to NP-completeness, and indicates some of the difficulties inherent in this particularly elusive and challenging problem. A comprehensive bibliography of papers relating to the graph isomorphism problem is given.
519 citations
TL;DR: In this paper, a semi-empirical method for the prediction of intermolecular forces was proposed for systems with a small number of electrons and leads to the conclusion that those systems behave as the internal atomic correlation energy was almost independent from the interatomic distance.
459 citations
TL;DR: It is shown here that cyclic loading, as naturally occurring in long bones, produces a flow of liquids through canaliculi so great that it significantly increases the efficiency of the transport mechanism operating between blood supply and osteocytes.
Abstract: WE show here that cyclic loading, as naturally occurring in long bones, produces a flow of liquids through canaliculi. The magnitude of such a stress-induced flow is so great that it significantly increases the efficiency of the transport mechanism operating between blood supply and osteocytes.
423 citations
TL;DR: The authors reviewed the literature concerning the controversy between dissonance and self-perception theories and suggested that the two theories should be regarded not as competing formulations but as complementary ones and furthermore that each theory is applicable only to its own specialized domain.
289 citations
TL;DR: The progress made on the Reconstruction Conjecture is reviewed, up to isomorphism, since it was first formulated in 1941 and a number of related questions are discussed.
Abstract: The Reconstruction Conjecture asserts that every finite simple undirected graph on three or more vertices is determined, up to isomorphism, by its collection of vertex-deleted subgraphs. This article reviews the progress made on the conjecture since it was first formulated in 1941 and discusses a number of related questions.
266 citations
TL;DR: Lucid is a formal system in which programs can be written and proofs of programs carried out because the statements in a Lucid program are simply axioms from which the proof proceeds by (almost) conventional logical reasoning.
Abstract: Lucid is a formal system in which programs can be written and proofs of programs carried out. The proofs are particularly easy to follow and straightforward to produce because the statements in a Lucid program are simply axioms from which the proof proceeds by (almost) conventional logical reasoning, with the help of a few axioms and rules of inference for the special Lucid functions. As a programming language, Lucid is unconventional because, among other things, the order of statements is irrelevant and assignment statements are equations. Nevertheless, Lucid programs need not look much different than iterative programs in a conventional structured programming language using assignment and conditional statements and loops.
TL;DR: In this article, the authors present a classified bibliography organized into six sections-static design models, dynamic control models, models involving queue discipline control, miscellaneous models, tutorial and survey papers, and books that have specific portions devoted to design and control.
Abstract: This paper presents a classified bibliography organized into six sections-static design models, dynamic control models, models involving queue discipline control, miscellaneous models, tutorial and survey papers, and books that have specific portions devoted to design and control. Some of the above categories are further subdivided when appropriate, and explanations of the types of models in each category and subcategory precede the actual list of references. Papers that fall into more than one category are cross-referenced.
TL;DR: The increasingly important role assigned to cognitive factors not only challanges the traditional tenets of behavior therapy but also augments and expands the highly specific procedures which have characterized the field in recent years.
Abstract: The increasingly important role assigned to cognitive factors not only challanges the traditional tenets of behavior therapy but also augments and expands the highly specific procedures which have characterized the field in recent years Self—instructional training, first used with hyperactive children to change maladaptive thinking processes, and stress inoculation training, used successfully with both clinical and highrisk non—clinical population to help them alter conceptualizations, employ coping skills, and successfully confront stressful situations, illustrate the possibilities of a broad-spectrum approach The theoretical implications of increased interest in cognitive factors direct attention to the nature of the client—therapist interaction, mediation, the content of inner speech and the client's appraisal of outcome as active ingredients of the change process
TL;DR: The study was conducted to compare film generated acceleration curves with the analog acceleration curves of single segment movements, and found digital filtering combined with a first order finite difference technique produced acceleration data very closely approximating the analog signals.
TL;DR: The present investigation is a study of the properties of 2-dimensional (2-D) and S-D network models of capillary tubes generalized for any pore size distribution and it was found that the accessibility of pores and the pseudo dead-end pore fractions are determined by the dimensionality of the network, the coordination num ber of thenetwork and the topology of pore inter connectedness at the microscopic level.
Abstract: The present investigation is a study of the properties of 2-dimensional (2-D) and S-D network models of capillary tubes generalized for any pore size distribution. These properties include: (i) the breakthrough condi tion subject to the step-by-step invasion of a nonwetting phase into an empty (evacuated) 2-D or S-D network; (ii) the accessibility of pores; and (iii) the "pseudo" dead end pore fractions, characteristic of the fractional amount of the non-conducting penetrated pore volume. It was found that for infinitely deep networks the bre",kthrou!1h condition is defined by the coordination number Z and the dimensionality of the network through tke relations Pc.Z =::: 2 and Pr.Z = 1.5 for 2-D and S-D networks, respectively. 2-D networks do not allow the existence of bicontinua and, as such, they cannot simulate realistically 2-phase flow phenomena. Generalized saturation plots for the accessibility of pores and the pseudo dead-end pore fractions have been estab lished. It was found that the accessibility of pores and the pseudo dead-end pore fractions are determined by (i) the dimensionality of the network, (ii) the coordination num ber of the network and (iii) the topology of pore inter connectedness at the microscopic level. The accessibility of pores found in the network analysis of the penetration process into 2-D and s-D networks has been critically tested by using: (i) the experimentally known mercury porosimetry capillary pressure curves of two sandstone samples of known "complete" pore size distribution and the experimentally determined accessibility functions; and (ii) the saturation at breakthrough observed in mer cury penetration experiments. It was established that: (1) the accessibility of pores predicted by the network analysis of 2-D and 3-D network models of randomly dis tributed capillary tubes does not agree quantitatively with the quantities obtained experimentally;
TL;DR: In this article, the generalizability of the Fishbein model for behavior prediction was extended to a new field behavior, alcohol drinking by adolescents, and it was found that the predictability of alcohol-drinking intentions ( BI ) declined when attitudes ( A act ) and normative beliefs ( NB ) did not correspond with BI in terms of alcohol type and drinking situation (home, party, or pub).
TL;DR: In this paper, an equation for the rate of capillary rise in porous media with nonuniform pores was derived on the basis of a three-dimensional network model of pore structure, consisting of a repeating capillary element with step changes in its diameter.
TL;DR: In this article, the authors present the graphical method of estimating the parameters of the Weibull distribution, and present the method of Maximum Likelihood as an objective technique, developed by statisticians for improving the estimates of the weibull parameters, especially for censored experiments.
Abstract: The time to electric breakdown, and the electric field necessary to result in breakdown of solid insulation, seem to be best represented by a Weibull probability distribution. This tutorial paper reviews the graphical method of estimating the parameters of the Weibull distribution. It also presents the method of Maximum Likelihood as an objective technique, developed by statisticians for improving the estimates of the Weibull parameters, especially for censored experiments. Procedures for calculating confidence intervals are also given. It is shown in an example that the confidence intervals can be very wide for sample sizes commonly used in dielectric life tests.
TL;DR: In this article, a generalized Newton dc load-flow program is presented for multiterminal HVDC systems, which accommodates various configurations of HVdc systems and can interface with any ac load flow program.
Abstract: Any configuration of multiterminal HVdc system is accommodated in a generalized Newton dc load-flow program. It readily interfaces with any ac load flow program. Pract ical operating requirements have been given particular attention to permit aspects such as converter transformer tap-limits, pole and bipolar dc outages, emergency pole-paralleling and detailed control and scheduling strategies. Examples are provided of typical solutions incorporating realistic dc and ac systems, and accomplished in conjunction with an established modern ac load flow program.
TL;DR: The language and sequence equivalence problem for DOL-systems is shown to be decidable and can be stated as follows: Given homomorphisms h, and h, on a free monoid z1* and a word D from Z*, is %rn(r,) = &“(o) for all n > O?
Abstract: FRISK Department of Computer Science, University of Waterloo, Waterloo, Ontario, Canada N2L 3GI The language and sequence equivalence problem for DOL-systems is shown to be decidable. In an algebraic formulation the sequence equivalence problem for DOL-systems can be stated as follows: Given homomorphisms h, and h, on a free monoid z1* and a word D from Z*, is %rn(r,) = &“(o) for all n > O?
TL;DR: A model for the growth of a solid in vitro tumor including the effects of non-uniformity in oxygen consumption and proliferation rate is developed in this paper, where appropriate equations which describe the diffusion of oxygen are set up and then solved.
Abstract: A model for the growth of a solid in vitro tumor including the effects of non-uniformity in oxygen consumption and proliferation rate is developed. The appropriate equations which describe the diffusion of oxygen are set up and then solved. The growth equation is formulated and a method of solution described. The results of this new model are compared with the predictions of an earlier model which assumes that the consumption of nutrient by live cells is uniform.
TL;DR: The coexistence of closely related species is shown to be common in temporary aquatic habitats and, as far as the most abundant taxa are concerned, the species composition is very stable from year to year.
Abstract: This, the second of two papers on the ecology of temporary streams, attempts a generalization of the unique features of these habitats. The fauna is shown to consist of three main groups: permanent stream species, facultative species and specialized species. The members of certain major taxonomic groups tend to oversummer as similar stages in their life cycles and the oversummering method used reflects the type of life cycle exhibited by a particular species. These variations in life cycle lead to faunal succession. The coexistence of closely related species is shown to be common in temporary aquatic habitats and, as far as the most abundant taxa are concerned, the species composition is very stable from year to year.
TL;DR: In this paper, the time independent diagrammatic technique based on the mathematical methods of quantum electrodynamics (second quantization, Wick's theorem, Feynman-like diagrams) is combined with graphical techniques of spin algebras to derive general expressions for the matrix elements of spin independent one-and two-particle operators between spin symmetry adapted ground, mono-and bi-excited configurations of a closed shell system.
Abstract: The time independent diagrammatic technique based on the mathematical methods of quantum electrodynamics (second quantization, Wick's theorem, Feynman-like diagrams) is combined with graphical techniques of spin algebras to derive general expressions for the matrix elements of spin independent one- and two-particle operators between spin symmetry adapted ground, mono- and bi-excited configurations of a closed shell system. Two coupling schemes are considered for bi-excited states and their relative merits are discussed. Finally, the results are used to derive compact expressions for the coupling coefficients of the direct configuration interaction from molecular integrals (CIMI) method.
TL;DR: A new closed form expression for Watson's result on the simple cubic lattice is given in terms of gamma functions.
Abstract: The known exact expressions for extended Watson integrals relating to various cubic and modified cubic lattices are summarized. A new closed form expression for Watson's result on the simple cubic lattice is given in terms of gamma functions.
TL;DR: The problem of scheduling days off in continuous seven-day-a-week operations under a variety of day-off policies, when demand for manpower is N on weekdays and n on weekend days, is examined.
Abstract: We examine the problem of scheduling days off in continuous seven-day-a-week operations under a variety of day-off policies, when demand for manpower is N on weekdays and n on weekend days. We consider a number of policies governing employee work assignments and in each case we give a formula for the minimum workforce size and a schedule construction algorithm.
TL;DR: In this article, the authors derived the energy spectrum for the N-dimensional isotropic harmonic oscillator and for both the nonrelativistic and the relativistic n-dimensional hydrogen atom.
Abstract: A very general realization of the so(2, 1) algebra, which easily follows from the basic commutation relations that are satisfied by any pair of mutually conjugate generalized coordinates and momenta, is constructed. Using special cases of this general realization, and closely following the well known derivation of the eigenvalue spectra of the angular-momentum operators, based on the so(3) algebra, we derive the energy spectrum for the N-dimensional isotropic harmonic oscillator, and for both the nonrelativistic and the relativistic N-dimensional hydrogen atom. Special attention is given to a simple derivation of the form of these Hamiltonians in terms of the so(2, 1) algebra generators. In particular, the usually exploited tilting transformation is avoided, and the whole derivation is presented in an extremely simple and straightforward way. The present approach stresses the similarity and mutual relationship between the systems studied and, in addition to introducing some novel techniques and providing considerable insight into the overall structure of these problems, also has a definite pedagogical value.
TL;DR: In this article, the specific rate constant for termination reaction between two flexible polymer molecules with active chain ends has been considered in relation to the segmental diffusion of chain ends in solution.
Abstract: The specific rate constant for the termination reaction between two flexible polymer molecules with active chain ends has been considered in relation to the segmental diffusion of chain ends in solution. The probability of reaction between two chain ends per unit time when the centers of gravity of two polymer molecules are at a distance of separation has been calculated by using the Smoluchowski equation and a Gaussian distribution of chain ends. The time during which two polymer molecules are in contact has also been calculated by using the diffusion equation and the potential energy function for intermolecular interaction. The rate constant may then be completely expressed as a complex function of the intramolecular linear expansion factor, molecular weight, and the frictional properties of the reacting polymers' segment. This expression predicts that the rate constant is inversely proportional to solvent viscosity, decreasing with increasing molecular weight to some extent, and is affected by the excluded volume effect and chain flexibility. The complete expression for the rate constant has been simplified and the result compared with experimental data. Close agreement is found between the calculated rate constants and those experimentally obtained.
TL;DR: In this article, a study was made to determine whether the levels of salt resulting from road runoff affect the drift of benthic invertebrates of urban streams in southern Ontario.