Showing papers by "University of Waterloo published in 1978"
TL;DR: This paper examined the relation between each of several attitudinal qualities and attitude-behavior consistency and found that direct experience with an attitude object may produce an attitude that is both better defined and more confidently held than an attitude formed through more indirect means.
588 citations
425 citations
TL;DR: In this article, the authors examined the hypothesis that the confidence with which an attitude is held may be a mediating variable in the observed relationship between the manner of attitude formation and attitude-behavior consistency.
Abstract: Previous research has demonstrated that behavior is more accurately predicted from attitudes formed via direct, behavioral interaction with the attitude object than from attitudes developed via indirect, nonbehavioral experience. The present research examined the hypothesis that the confidence with which an attitude is held may be a mediating variable in the observed relationship between the manner of attitude formation and attitude-behavior consistency. In the first experiment, it was demonstrated that subjects who formed their attitudes through direct experience held those attitudes more confidently and behaved more consistently with those attitudes than did subjects who formed their attitudes through indirect experience. In the second experiment, it was found that, regardless of the manner of attitude formation, subjects who were led to believe that they held their attitudes confidently displayed greater attitude-behavior consistency than did subjects led to believe that they held their attitudes with little confidence. Taken together, the results suggest that it may be fruitful to view confidence both as a variable which mediates the effect of the manner of attitude formation on attitude-behavior consistency and as one which, independent of how an attitude is formed, acts as a determinant of attitude-behavior consistency.
416 citations
355 citations
TL;DR: In this article, the relative influences of a large number of potentially important variables on response time in word-nonword classification tasks were determined, and more stringent controls over stimulus selection procedures were recommended.
347 citations
TL;DR: In this article, a variety of substituted, fused and bridged ring systems, including natural products, are discussed systematically illustrating the possibilities, limitations, and common features of this cyclization reaction and its reverse ring-opening process.
Abstract: Thermal cyclizations of appropriate dienes, enynes and related unsaturated systems, some of them carried out on an industrial scale, demonstrate increasingly the preparative power of the intramolecular ene reaction. A variety of substituted, fused and bridged ring systems, including natural products, are thus easily accessible in a regio- and stereo-selective manner. Numerous examples are discussed systematically illustrating the possibilities, limitations, and common features of this cyclization reaction and its reverse ring-opening process.
332 citations
01 Jan 1978
300 citations
TL;DR: In this article, the authors focus on how to avoid isomorphism search when cataloguing combinatorial configurations, and present a recursive procedure that produces larger graphs from an existing list of smaller graphs.
Abstract: Publisher Summary This chapter focuses on how to avoid isomorphism search when cataloguing combinatorial configurations. This is a recursive procedure that produces larger graphs from an existing list of smaller graphs. Thus for graphs on a given number of nodes, the graphs having q + 1 edges from a list of graphs having q edges is produced. It is therefore necessary to have a method for detecting the isomorphism. For graphs or digraphs in general, this is known to be a difficult problem, but because these catalogs are necessarily restricted to fairly small graphs, the detection of isomorphs is not a great hurdle.
256 citations
16 Oct 1978
TL;DR: When selecting from, or sorting, a file stored on a read-only tape and the internal storage is rather limited, several passes of the input tape may be required.
Abstract: When selecting from, or sorting, a file stored on a read-only tape and the internal storage is rather limited, several passes of the input tape may be required. We study the relation between the amount of internal storage available and the number of passes required to select the Kth highest of N inputs. We show, for example, that to find the median in two passes requires at least Ω(N1/2) and at most O(N1/2 log N) internal storage. For probabilistic methods, Θ(N1/2) internal storage is necessary and sufficient for a single pass method which finds the median with arbitrarily high probability.
240 citations
TL;DR: In this paper, it was shown that for planar graphs, the lower bound on the cardinality of a feedback set of a directed graph G is equivalent to the dual lower bound of the corresponding lower bound for a transversal of directed cuts.
Abstract: This minimax equality was conjectured about a decade ago by one of the authors ([7; page 43], [8], [9]) and, independently, by Neil Robertson. It arose in the study of a problem posed several years prior to that by John Runyon [5; page 299]: for a directed graph, give an efficient algorithm for finding a minimum feedback set. A feedback set is a set of edges that contains at least one edge of each directed circuit of the graph. A lower bound on the cardinality of a feedback set of a directed graph G is given by the cardinality of a maximum disjoint collection of directed circuits of G. The lower bound is not reached for all graphs, but experiment suggested that it is attained for all planar graphs. The attainment of this lower bound is equivalent, for planar graphs, to the attainment in the dual graph of the analogous lower bound for the cardinality of a transversal of directed cuts. This equivalence for planar graphs does not hold for all graphs. Indeed, the conjectured minimax equality, in its directed cut formulation, was extended to include all finite directed graphs. This is the Theorem which this paper proves; the following Dual Theorem is a corollary.
229 citations
TL;DR: As a result of the complexity shown in these patterns it is cautioned that fundamental relationships that may have been derived from controlled biomechanical experiments are not likely to apply to more normal movements such as gait.
Abstract: Experiments were conducted on normal level gait to determine the synergistic patterns present in the forces causing joint moments and those associated with the generation, absorption and transfer of mechanical energy. The following generalizations can be made about the patterns: (i) During swing phase three forces (gravitational, muscle and knee joint acceleration) are responsible for shank rotation, and are shown to act together during both acceleration and deceleration.--(ii) The patterns of generation, absorption and transfer of mechanical energy at the joints are detailed. These patterns demonstrate inter-segment transfers of energy through the joint centres, and through the muscles, as well as the more recognized generation and absorption by the muscles themselves.--As a result of the complexity shown in these patterns it is cautioned that fundamental relationships that may have been derived from controlled biomechanical experiments (such as horizontal flexion and extension of the forearm) are not likely to apply to more normal movements such as gait.
TL;DR: This paper found that direct experience affects the attitude formation process by altering the way in which the available information is processed, and that empathic subjects behave more consistently with their own reported attitudes toward those puzzles than control subjects.
Abstract: Attitudes formed through direct behavioral experience with an attitude object have been found to better predict later behavior than attitudes formed through indirect experience. An experiment was conducted to test the hypothesis that an information processing difference exists between direct and indirect experience. Subjects watched a videotape of an individual working examples of a variety of puzzles under instructions to empathize with that person or not. Taking the perspective of the person having the direct experience led Empathy subjects to behave more consistently with their own reported attitudes toward those puzzles than Control subjects. The results suggest that direct experience affects the attitude formation process by altering the way in which the available information is processed.
TL;DR: In this paper, the authors considered the situation of a single item having a deterministic, time-varying demand pattern and determined the production lot sizes, so as to minimize the total of setup and carrying costs subject to production capacity restrictions that can vary with time.
Abstract: We consider the situation of a single item having a deterministic, time-varying demand pattern. Production lot sizes, so as to minimize the total of setup and carrying costs, are to be determined subject to production capacity restrictions that can vary with time. Two important theorems concerning properties of the optimal solution are exploited in developing a tree search algorithm. In addition, other properties are utilized to reduce the amount of search necessary. Results of extensive tests are presented and discussed.
TL;DR: The use of phosphorus compounds as catalysts has also accelerated in the last decade as mentioned in this paper, and it is not unexpected, then, to find that the use of compounds of phosphorus can also accelerate the development of catalysts.
Abstract: Although carbon is often considered as the dominant element in terms of covalent bond formation, phosphorus can undoubtedly be considered a s a serious competitor for this position [1]. Further, at least in principle, phosphorus is potentially capable of forming more compounds than carbon. For a variety of reasons, both academic and practical, interest in phosphorus compounds has increased markedly over the last decade. It is not unexpected, then, to find that the use of compounds of phosphorus as catalysts has also accelerated. Unfortunately, a s is often the case in science, the practice outruns the theory with such catalysts, but industrialists and academicians alike have recently displayed an enhanced interest in the mechanisms of catalytic activity on such catalysts.
TL;DR: An algorithm is presented that finds K, the set of all keys for agiven set A of attribute names and a given set D [0] of functional dependencies, in time polynomial in A, D, and |K|.
TL;DR: The hierarchy is infinite for any alphabet with two or more letters; over an alphabet of one letter the hierarchy is finite; in fact, B(2) = B(1).
TL;DR: The results showed a marked left hand advantage only in the thumb positioning task suggesting that the right hemisphere was superior in performing this task.
TL;DR: It is shown that for machines with two-dimens iona l rec tangula r grid connect ivi ty (such as I L L I A C IV), mui t tphcat lon and inversion o f NxN matrices inherent ly requi re O(N) steps, even if the process ing e lements are no t cons t ra ined to execute identical instruct ions.
Abstract: In this pape r it is shown how da ta movemen t , r a the r than ar i thmet ic opera t ions , can be the hml tmg fac tor in the pe r fo rmance o f paral lel compu te r s on matr ix computa t ions In par t icular it is p roved that for machines with two-dimens iona l rec tangula r grid connect ivi ty (such as I L L I A C IV), mui t tphcat lon and inversion o f NxN matrices inherent ly requi re O(N) steps, even if the process ing e lements are no t cons t ra ined to execute identical instruct ions.
TL;DR: It is shown that cellulose degradation kinetics are expected to be strongly affected by the ratio of endo‐ to exocellulases in the reaction mixture as indicated by previous experimental data, and the substrate degree of polymerization, a factor not fully appreciated in previous studies.
Abstract: A generalized mechanistic model for the enzymatic hydrolysis of cellulose is developed and expressed mathematically. The model is based on Michaelis–Menten-type kinetics for concurrent random and endwise attack of the substrate involving end-product inhibitions and three types of enzymes: an endo-β;-1,4-glucanase, an exo-β-1,4-glucanase, and β-glucosidase. Basic parameters of the model which can explain synergistic and other effects observed experimentally are quantified and discussed. It is shown that cellulose degradation kinetics are expected to be strongly affected by the ratio of endo- to exocellulases in the reaction mixture as indicated by previous experimental data, and the substrate degree of polymerization, a factor not fully appreciated in previous studies, which appear to be overridingly important in many practical cases.
TL;DR: A "move to root" heuristic is shown to yield an expected search time within a constant factor of that of an optimal static binary search tree.
Abstract: We consider heuristics which attempt to maintain a binary search tree in a near optimal form, assuming that elements are requested with fixed, but unknown, independent probabilities. A "move to root" heuristic is shown to yield an expected search time within a constant factor of that of an optimal static binary search tree. On the other hand, a closely related "simple exchange" technique is shown not to have this property. The rate of convergence of the "move to root" heuristic is discussed. We also consider the more general case in which elements not in the tree may have non-zero probability of being requested.
TL;DR: In this article, the authors consider a continuous review system with discrete compound Poisson demand, convex holding-penalty cost and fixed order cost and develop recursive formulae to calculate the cost for any pair s, S.
Abstract: We consider inventory policies for a continuous review system with discrete compound Poisson demand, convex holding-penalty cost and fixed order cost. Beckmann has showri that under these conditions s, S policies are optimal. We develop recursive formulae to calculate the cost for any pair s, S. Relations among s, S, S-s and the cost are produced that lead to an efficient determination of the optimal s and S. Tighter bounds are utilized than those obtained by Veinott and Wagner for the analogous case of periodic review. Sensitivity considerations are discussed.
TL;DR: In this paper, a new approach to the direct determination of excitation energies and various attachment or detachment energies, such as electron affinities and ionization potentials, is presented, based on the coupled-cluster ansatz for the trial wave function, generalized to the open-shell excited or ionized states in a way which enables a variation principle to be used, assuming that the closed-shell ground-state coupledcluster wave function is known.
Abstract: A new approach to the direct determination of excitation energies and various attachment or detachment energies, such as electron affinities and ionization potentials, is presented. It is based on the coupled-cluster ansatz for the trial wave function, generalized to the open-shell excited or ionized states in a way which enables a variation principle to be used, assuming that the closed-shell ground-state coupled-cluster wave function is known. The conditions for the applicability of this approach are discussed, and the basic formalism is derived. A technique enabling a systematic elimination of disconnected clusters in a general open-shell case is presented and used. An example pertaining to ionization processes is worked out in some detail. Finally, the relationship of the presented approach to configuration-interaction and perturbative Green's-function approaches is briefly outlined.
TL;DR: In this article, the doublet stability of the SCF solutions for the allyl radical is re-examined for various ab-initio model hamiltonians, based on the minimum, doublezeta and double-zeta plus polarization atomic orbital basis sets in the LCAO scheme.
Abstract: The doublet stability of the SCF solutions for the allyl radical is re-examined for various ab-initio model hamiltonians, based on the minimum, double-zeta and double-zeta plus polarization atomic orbital basis sets in the LCAO scheme. The calculations are carried out for a wide range of the C-C bond lengths (1.3 A to 2·0 A). In all cases the critical bond length, separating regions of stability and instability, is found to be shorter than the corresponding equilibrium C-C bond length (1·36 A versus 1·44 A, respectively, for the minimum basis set). In contrast to the results of McKelvey and Berthier we find that the doublet-stability problem yields at most one negative eigenvalue in the whole range of the C-C bond lengths studied, this implying only one possible (other than spin) symmetry breaking, in complete agreement with the semi-empirical PPP model results for this system. The basis dependence of the doublet instability is also re-examined and the generality of this phenomenon is firmly established f...
TL;DR: In this article, the potential of intramolekularen En-Reaktion is discussed. And a number of different types of cyclisierungs von Dienen, Eninen, Enonen and Enonen are illustrated.
Abstract: Thermische Cyclisierungen von Dienen, Eninen, Enonen und ahnlichen ungesattigten Systemen illustrieren das praparative Potential der intramolekularen En-Reaktion. Eine Fulle substituierter, anellierter und uberbruckter Ringsysteme, darunter auch Naturstoffe, sind so auf regio- und stereoselektive Weise zuganglich. Zahlreiche Beispiele dienen dazu, die Moglichkeiten, Grenzen und gemeinsamen Gesetzmasigkeiten dieser Cyclisierungs- und der dazu inversen Ringoffnungs-Reaktion zu umreisen. Manche dieser Cyclisierungen sind in industrieller Grosenordnung durchfuhrbar.
TL;DR: In this article, a bundle of polypropylene tubes contained inside a polyvinyl chloride (PVC) pipe that is installed in the aquifer is used as a point water sampler and piezometer.
Abstract: A simple inexpensive device for sample collection and for monitoring of ground-water potential at many levels from a single borehole installation has been developed. The device consists of a bundle of polypropylene tubes contained inside a polyvinyl chloride (PVC) pipe that is installed in the aquifer. Each tube protrudes through the wall of the pipe at a different elevation where it serves as a point water sampler and piezometer. The tip of each tube is encased in fine-meshed stainless-steel screening. The device is best suited for use in cohesionless deposits and where the piezometric levels are close enough to ground surface to enable samples to be obtained by suction methods. It can be conveniently installed using a hollow-stem auger, driven casing or wash-boring methods. The usefulness of this multilevel sampling device has been demonstrated in detailed monitoring of a leachate plume from a sanitary landfill.
TL;DR: In this paper, a heuristic approach for determining the timing and the sizes of replenishments of an item having probabilistic demand with an average value that varies significantly with time is proposed.
Abstract: In this paper we deal with an important, practical problem, namely how to determine the timing and the sizes of the replenishments of an item having probabilistic demand with an average value that varies significantly with time. We provide a heuristic approach to resolving this complex problem; this approach permits sequential answers to the following questions: i) is it time to order? ii) how long a period should the replenishment be expected to cover? iii) how large should the replenishment be?
TL;DR: In this paper, the authors present a review of methods of constructing confidence intervals for parameters or other characteristics of the Weibull or extreme value distribution, with emphasis on the flexibility of the method and on the computations which are necessary to use it.
Abstract: This paper reviews methods of constructing confidence intervals for parameters or other characteristics of the Weibull or extreme value distribution. The conditional method of obtaining confidence intervals is stressed, with emphasis on the flexibility of the method, and on the computations which are necessary to use it.
TL;DR: The phospholipid content of rough and smooth microsomal fractions from cotyledons of germinating bean declines as the tissue becomes senescent, and the patterns of change in this ratio correlated with previously reported changes in bulk lipid transition temperature, suggesting that the increase in sterol level may contribute to changes in phase behaviour of the membranes during senescence.
TL;DR: Two series of qualitative collections of the benthic macroinvertebrates inhabiting the wave-zone (0-2m) along the exposed Canadian shores of the St. Lawrence Great Lakes were made in the summer of 1974.