Showing papers by "University of Toronto published in 1970"
TL;DR: A generalization of the sampling method introduced by Metropolis et al. as mentioned in this paper is presented along with an exposition of the relevant theory, techniques of application and methods and difficulties of assessing the error in Monte Carlo estimates.
Abstract: SUMMARY A generalization of the sampling method introduced by Metropolis et al. (1953) is presented along with an exposition of the relevant theory, techniques of application and methods and difficulties of assessing the error in Monte Carlo estimates. Examples of the methods, including the generation of random orthogonal matrices and potential applications of the methods to numerical problems arising in statistics, are discussed. For numerical problems in a large number of dimensions, Monte Carlo methods are often more efficient than conventional numerical methods. However, implementation of the Monte Carlo methods requires sampling from high dimensional probability distributions and this may be very difficult and expensive in analysis and computer time. General methods for sampling from, or estimating expectations with respect to, such distributions are as follows. (i) If possible, factorize the distribution into the product of one-dimensional conditional distributions from which samples may be obtained. (ii) Use importance sampling, which may also be used for variance reduction. That is, in order to evaluate the integral J = X) p(x)dx = Ev(f), where p(x) is a probability density function, instead of obtaining independent samples XI, ..., Xv from p(x) and using the estimate J, = Zf(xi)/N, we instead obtain the sample from a distribution with density q(x) and use the estimate J2 = Y{f(xj)p(x1)}/{q(xj)N}. This may be advantageous if it is easier to sample from q(x) thanp(x), but it is a difficult method to use in a large number of dimensions, since the values of the weights w(xi) = p(x1)/q(xj) for reasonable values of N may all be extremely small, or a few may be extremely large. In estimating the probability of an event A, however, these difficulties may not be as serious since the only values of w(x) which are important are those for which x -A. Since the methods proposed by Trotter & Tukey (1956) for the estimation of conditional expectations require the use of importance sampling, the same difficulties may be encountered in their use. (iii) Use a simulation technique; that is, if it is difficult to sample directly from p(x) or if p(x) is unknown, sample from some distribution q(y) and obtain the sample x values as some function of the corresponding y values. If we want samples from the conditional dis
14,965 citations
TL;DR: This paper found that both pleasingness and interestingness increase with novelty, and that simple stimuli became less pleasant as they became less novel, while complex stimuli declined less or became more pleasant.
Abstract: Two experiments, in which Ss were exposed to sequences of colored shapes, investigated effects on ratings of “pleasingness” and “interestingness” of variables that had previously been shown to affect ratings of “novelty.” The results indicate, on the whole, that both pleasingness and interestingness increase with novelty. These findings run counter to those of experiments indicating an inverse relation between novelty and verbally expressed preference. Two further experiments examined effects of some variables that might account for this apparent discrepancy. Homogeneous sequences declined in judged “pleasantness” more than sequences in which several stimuli were interspersed, and simple stimuli became less pleasant as they became less novel, while complex stimuli declined less or became more pleasant. The findings are related to hypotheses regarding mechanisms of hedonic value. Two crucial predictions were confirmed in a fifth experiment.
1,192 citations
TL;DR: The ratios between total saturated to total unsaturated fatty acids during ischemia and after electroshock suggest a predominance of the hydrolysis of the β-ester bond of phospholipids.
852 citations
TL;DR: An adenosine triphosphatase has been purified approximately 6-fold from sarcoplasmic reticulum through the use of deoxycholate and salt fractionation and the rate of ATP-ADP exchange and the level of phosphorylation are both increased by a factor commensurate with the increase in ATPase activity.
778 citations
TL;DR: A simple, chemically defined medium consisting of sodium glutamate, proline, cystine, salts, and growth factors is described, which is suitable for the large-scale production of phase I Bordetella pertussis, which yielded vaccines which were non-toxic to mice and guinea pigs and had good mouse-protective antigen levels.
Abstract: SUMMARY: A simple, chemically defined medium is described consisting of sodium glutamate, proline, cystine, salts, and growth factors, which is suitable for the large-scale production of phase I Bordetella pertussis. More than 30 x 109 organisms/ml. were produced in 48 to 72 h. growth in shake flasks and fermentors. The cultures were detoxified by the addition of 0.14% formalin to yield vaccines which were non-toxic to mice and guinea pigs and had good mouse-protective antigen levels. The antigenic stability was satisfactory after storage of the final vaccines at elevated temperatures.
639 citations
TL;DR: The apparent location of the glycosyltransferases in the Golgi apparatus suggests that these enzymes may be involved in terminating the synthesis of plasma glycoproteins by the liver during secretion, and may possibly be required for secretion of these proteins.
579 citations
TL;DR: In this paper, the impact of a leader's behavior (in terms of initiation of structure and consideration) on the subordinates' path-goal instrumentalities is examined, and data relevant to the theoretical scheme are presented for two organizations, although in one organization a set of positive results emerges, while in the second there is a consistent failure to support hypothesized relationships.
518 citations
TL;DR: In this article, the effectiveness of retrieval cues depends upon the specific format of the to-be-remembered (TBR) words at the time of their storage, regardless of how strongly the cues are associated with the TBR words in other situations.
Abstract: Data from three experiments are reported in support of the encoding specificity hypothesis of retrieval: the effectiveness of retrieval cues depends upon the specific, format o f encoding of the to-be-remembered (TBR) words at the time o f their storage, regardless of how strongly the cues are associated with the TBR words in other situations. In the critical experimental conditions, TBR words were presented for study in presence of weakly associated cue words, Recall of the TBR words in the presence of these cues was greatly facilitated in comparison with noncued recall; recall of the TBR words in presence of their strongest normative associates, which had not been seen at input, did not differ from noncued recall.
517 citations
TL;DR: In this paper, a second-order, linear, damped system with self-excited wake-oscillators is proposed to model the aerodynamic lift force and the instantaneous value of a fluctuating lift coefficient, whose characteristics are derived from existing experimental data.
Abstract: The main feature is the representation of fluctuating lift behavior in terms of a proposed wake-oscillator. The primary purpose of the paper is to demonstrate the potential of the wake-oscillator concept for future studies. The elastically mounted cylinder is modeled as a second-order, linear, damped system. The aerodynamic lift force is proportional to the instantaneous value of a fluctuating lift coefficient. The instantaneous lift coefficient is derived from the response of a proposed lift-oscillator, whose characteristics are deduced from existing experimental data. This oscillator is self-excited, its natural frequency is proportional to wind speed, and it is subjected to a coupling term proportional to the transverse cylinder velocity.
413 citations
TL;DR: On comparison with rabbit platelets prepared from blood taken into EDTA, the only differences observed were the much greater sensitivity to ADP and a higher calcium content; platelet morphology, nucleotide levels, and conversions of 14C‐ATP and 14C-ADP at the platelet membrane were similar.
Abstract: Summary A method is described for the preparation of suspensions of washed rabbit platelets which will aggregate upon the addition of low concentrations of ADP that are effective in citrated plasma. This method involves collecting blood into ACD, low pH, removal of calcium, and maintenance of magnesium during the isolation procedure. A protein (albumin) and glucose are included in the washing and suspending solutions. Rabbit platelets prepared in this way retained fibrinogen on their surface. On comparison with rabbit platelets prepared from blood taken into EDTA, the only differences observed were the much greater sensitivity to ADP and a higher calcium content; platelet morphology, nucleotide levels, and conversions of 14C-ATP and 14C-ADP at the platelet membrane were similar.
394 citations
TL;DR: The finding that males were somewhat more commonly affected than were females in patients who responded to general anaesthetics with malignant hyperthermia does not contradict previous observations of dominant inheritance of the syndrome.
Abstract: Information was collected on 89 patients who responded to general anaesthetics with malignant hyperthermia. The syndrome occurred at the rate of about one in 14,000 anaesthetics among a hospital population of children. The patient mortality was 64 per cent. The finding that males were somewhat more commonly affected than were females does not contradict previous observations of dominant inheritance of the syndrome. About one-third of patients had relatives who were also affected with malignant hyperthermia, although a few patients had had previous uneventful general anaesthetics. The racial origin was varied. A pre-existing muscle or musculoskeletal disease was present more frequently than expected in patients who manifested rigidity.
TL;DR: It is shown that the re ordered graphs form a sufficiency condition for isomorphism; namely, if the reordered graphs are identical, then the given graphs are isomorphic.
Abstract: A procedure for determining whether two graphs are isomorphic is described. During the procedure, from any given graph two graphs, the representative graph and the reordered graph, are derived. The representative graph is a homomorphic image of the original graph; the reordered graph is constructed from the representative graph to be isomorphic to the given graph. Unique labels are assigned to the vertices of both derived graphs. It follows that two repre- sentative graphs or two reordered graphs are isomorphic if and only if they are identical. A conjecture states that the representative graphs exhibit the automorphism partitioning of the given graph. The representative graphs form a necessity condition for isomorphism; namely, if the representative graphs are not identical, then the given graphs are not isomorphic. The converse is true for trees and follows from the conjecture for other types of graphs. It is also shown that the reordered graphs form a sufficiency condition for isomorphism; namely, if the reordered graphs are identical, then the given graphs are isomorphic. The converse follows from the conjecture. The time required to determine both derived graphs depends on a power of n, the order of the given graph. This power is a function of an adjacency property known as the strong regu- larity of the given graph. For graphs that do not contain a strongly regular transitive sub- graph, the power is, at worst, five.
TL;DR: The observations suggest that the metabolic error in hyperthermia with rigidity causes intracellular calcium metabolism to be vulnerable to drugs.
TL;DR: The authors found that a multilingual person's different languages exist in relative isolation from each other, and that organization of list words into higher-order memory units is more difficult between different languages than within a single language.
TL;DR: A simple physicochemical assay for the quantitation of enhanced vascular permeability in inflammation was described and it was shown that the assay is applicable to the study of inflammatory lesions induced with known chemical mediators and that associated with thermal injury.
Abstract: SummaryA simple physicochemical assay for the quantitation of enhanced vascular permeability in inflammation was described. It was shown that the assay is applicable to the study of inflammatory lesions induced with known chemical mediators, to the study of enhanced vessel permeability associated with the Arthus reaction, and that associated with thermal injury.
TL;DR: A recurrent problem in the study of recognition memory has been that of combining hits and false alarms (or correct and incorrect responses) into a single index of performance as discussed by the authors, which has been viewed in terms of "correcting for chance success".
Abstract: A recurrent problem in the study of recognition memory has been that of combining hits and false alarms (or correct and incorrect responses) into a single index of performance. That the proportion of correct responses in a yes/no or multiple-choice recognition test may in some way be contaminated by factors other than the state of the memory system has never been seriously disputed, but only recently has the question received detailed and systematic attention. Traditionally the problem has been viewed in terms of "correcting for chance success"; in current terminology, and stated more generally, it is a problem of providing an adequate theory of the decision system which maps a given state of the memory system into an overt response. The reasons for this increased attention to decision processes in memory are not difficult to trace. In the first place, the development of quantitative theories of recognition memory has necessitated a precise and explicit account of how the memory and decision systems interact to produce a given response. If a theory of memory is to be tested against data from a recognition-me mory experiment, it is necessary to obtain performance measures that are independent of those parameters
TL;DR: The assumption of statistical independence of matrix elements leads to ensembles of Hamiltonians which involve simultaneous interactions between many particles as discussed by the authors, and the resultant (semicircular) spectra are quite different from the Gaussian spectra found for Ensembles properly restricted to involve only two-body interactions.
TL;DR: In this article, it was shown that if rank C = l, and if (A,B) are controllable, then a linear feedback of the output variables u = K*y, where K*is a constant matrix, can always be found, so that l eigenvalues of the closed-loop system matrix A + BK*C are arbitrarily close (but not necessarily equal) to l preassigned values.
Abstract: The following system is considered: \dot{x}= Ax + Bu y = Cx where x is an n vector describing the state of the system, u is an m vector of inputs to the system, and y is an l vector ( l \leq n ) of output variables. It is shown that if rank C = l , and if (A,B) are controllable, then a linear feedback of the output variables u = K*y, where K*is a constant matrix, can always be found, so that l eigenvalues of the closed-loop system matrix A + BK*C are arbitrarily close (but not necessarily equal) to l preassigned values. (The preassigned values must be chosen so that any complex numbers appearing do so in complex conjugate pairs.) This generalizes an earlier result of Wonham [1]. An algorithm is described which enables K*to be simply found, and examples of the algorithm applied to some simple systems are included.
TL;DR: It is postulated that cells of periodontal ligament and their progeny have the capacity to inhibit osteogenesis.
TL;DR: The activity of L-dopa decarboxylase was greatly reduced in the striatum, less so in the hypothalamus, and unchanged in the cortex of brains of patients with Parkinson's disease, but it appears that even in thestriatum enough activity remained to allow for the formation of dopamine from L-Dopa in patients treated with large doses of L.dopa.
Abstract: The activity of L- dopa decarboxylase was greatly reduced in the striatum, less so in the hypothalamus, and unchanged in the cortex of brains of patients with Parkinson9s disease. However, it appears that even in the striatum enough activity remained to allow for the formation of dopamine from L- dopa in patients treated with large doses of L- dopa.
TL;DR: A new method for the measurement of medium-chain triglycerides andMedium-chain fatty acids in feces is described and can be used to measure either fats gravimetrically, or fatty acids titrimetrically.
TL;DR: In this article, a model calculation is performed by which the magnitude and form of the anticipated atmospheric wave train may be assessed, and both are found to be consistent with observations already recorded, but the question as to whether the Lorentz force or the Joule dissipation is the more important exciting agency provided by the current, is left unanswered because of present uncertainties connected with the nature of the current itself.
TL;DR: Decoupling by dynamic compensation using algebraic machinery, considering state space extension role in pole assignment is discussed in this article, where it is shown that dynamic compensation can be used for pole assignment.
Abstract: Decoupling by dynamic compensation using algebraic machinery, considering state space extension role in pole assignment
TL;DR: In this article, the authors examined the relationship between avatars and the people they represent in terms of appearance and behavior, and found that people with more attractive avatars than their real selves will be somewhat more confident and extraverted in virtual worlds than they are in the real world.
Abstract: What is the relationship between avatars and the people they represent in terms of appearance and behavior? In this paper, we hypothesize that people (balancing motives of self-verification and self-enhancement) customize the image of their avatars to bear similarity to their real selves, but with moderate enhancements. We also hypothesize that virtual-world behavior (due to deindividuation in computer-mediated communication environments) is less restrained by normal inhibitions than real-world behavior. Lastly, we hypothesize that people with more attractive avatars than their real selves will be somewhat more confident and extraverted in virtual worlds than they are in the real world.
We examine these issues using data collected from Second Life residents using an in-world intercept method that involved recruiting respondents’ avatars from a representative sample of locations. Our quantitative data indicate that, on average, people report making their avatars similar to themselves, but somewhat more attractive. And, compared to real-world behavior, respondents indicate that their virtual-world behavior is more outgoing and risk-taking and less thoughtful/more superficial. Finally, people with avatars more attractive than their real selves state that they are more outgoing, extraverted, risk-taking, and loud than their real selves (particularly if they reported being relatively low on these traits in the real world). Qualitative data from open-ended questions corroborate our hypotheses.
TL;DR: In a solar eclipse, the moon shields a limited region of the earth's atmosphere from the heating effect of the solar radiation as discussed by the authors, causing the neutral gas to emit internal gravity waves that form a bow wave about the shadow region.
Abstract: In a solar eclipse, the moon shields a limited region of the earth's atmosphere from the heating effect of the solar radiation. This shadow travels through the earth's lower atmosphere at supersonic velocity, causing the neutral gas to emit internal gravity waves that form a bow wave about the shadow region. Tentative estimates of the amplitude of this wave indicate that it will be detectable well outside the area where the eclipse can be observed directly.