Showing papers by "University of British Columbia published in 1981"

The Framing of Decisions and the Psychology of Choice

Abstract: The psychological principles that govern the perception of decision problems and the evaluation of probabilities and outcomes produce predictable shifts of preference when the same problem is framed in different ways. Reversals of preference are demonstrated in choices regarding monetary outcomes, both hypothetical and real, and in questions pertaining to the loss of human lives. The effects of frames on preferences are compared to the effects of perspectives on perceptual appearance. The dependence of preferences on the formulation of decision problems is a significant concern for the theory of rational choice.

Open Ocean Momentum Flux Measurements in Moderate to Strong Winds

Abstract: Measurements of the momentum flux were made by the Reynolds flux and dissipation methods on a deep water stable tower operated by the Bedford Institute of Oceanography, A modified Gill propeller-vane anemometer was used to measure the velocity. Drag coefficients from 196 Reynolds flux measurements agree well with those reported in Smith (1980) based on independent observations at the same site. Based on 192 runs, a comparison of the dissipation and Reynolds flux results shows excellent agreement on average, for wind speeds from 4 to 20 m s−1. The much more extensive dissipation data set (1086 h from the tower and 505 h from the weathership PAPA, CCGS Quadra) was used to investigate the dependence of the drag coefficient on wind speed, fetch and stability. The drag coefficient reduced to 10 m height and neutral conditions (CDN), is independent of stability and fetch (for fetch/height ≳800) but increases with wind speed above 10 m s−1. Some time series of the momentum flux and drag coefficient are ...

Experimental black hole evaporation

Abstract: It is shown that the same arguments which lead to black-hole evaporation also predict that a thermal spectrum of sound waves should be given out from the sonic horizon in transsonic fluid flow.

Canyon geometry and the nocturnal urban heat island: Comparison of scale model and field observations

Abstract: A simple hardware scale model is used to simulate nocturnal cooling rates for rural and urban environments under calm and cloudless conditions. Comparison with field observations gathered under similar conditions shows the model capable of reproducing many of the features of the temporal development of urban heat islands and the long-wave radiative exchange in urban canyons. The model is used to investigate the roles played by rural/urban differences in geometry and thermal admittance. The results of the experiments show that canyon geometry in the central portion of a city (as measured by the sky view factor) is a relevant variable in producing nocturnal urban heat islands due to its role in regulating long-wave radiative heat loss. It is also demonstrated that this measure is central to the relationship between city size and heat island intensity. The importance of canyon geometry as a feature of urban design is discussed. Thermal admittance differences can also produce realistic heat island features but their magnitude requires quantification in the field.

The central cholinergic system studied by choline acetyltransferase immunohistochemistry in the cat

Abstract: An atlas of the distribution of cholinergic cell bodies, fibers, and terminals, as well as cholinoceptive cells, in the central nervous system of the cat (excluding the cerebellum) is presented from results obtained in immunohistochemical work on choline acetyltransferase. Cholinergic cell bodies are observed in more than forty areas, and cholinoceptive cells in sixty discrete areas of brain sections from the spinal cord to the olfactory bulb. The atlas is presented in seventy cross-sectional drawings of cat brain extending from the olfactory bulb to the upper cervical spinal cord.

Scaling Community Attitudes Toward the Mentally Ill

Abstract: The measurement of public attitudes toward the mentally ill has taken on new significance since the introduction of communitybased mental health care. Previous attitude scales have been constructed and applied primarily in a professional context. This article discusses the development and application of a new set of four scales explicitly designed to measure community attitudes toward the mentally ill. The scales represent dimensions included in previous instruments, specifically, authoritarianism, benevolence, social restrictiveness, and community mental health ideology, but are expressed in terms of an almost completely new set of items that emphasize community contact with the mentally ill and mental health facilities. Data from a study of community attitudes about neighborhood mental health facilities in Toronto are used to test the internal and external validity of the scales. Results of the analysis provide strong support for the validity of the scales and demonstrate their usefulness as explanatory and predictive variables for studying community response to mental health facilities.

Collocation Software for Boundary-Value ODEs

Abstract: The use of a general-purpose code, COLSYS, is described. The code is capable of solving mixed-order systems of boundary-value problems in ordinary differential equations. The method of spline collocation at Gaussian points is implemented using a B-spline basis. Approximate solutions are computed on a sequence of automatically selected meshes until a user-specified set of tolerances is satisfied. A damped Newton's method is used for the nonlinear iteration. The code has been found to be particularly effective for difficult problems. It is intended that a user be able to use COLSYS easily after reading its algorithm description. The use of the code is then illustrated by examples demonstrating its effectiveness and capabilities.

Utilization index: A modified approach to the estimation and comparison of nutrient utilization efficiency in plants

Abstract: The disadvantages of using utilization quotient (biomass per unit amount of nutrient present in biomass) in comparing nutrient utilization efficiencies of different varieties and species are discussed. A modified approach to the estimation of utilization efficiency is presented. A comparison of efficiencies of two plants calculated by this method gives an index which is the ratio of biomass ratio: tissue nutrient concentration ratio. Theoretical validity and advantages in practical application of this approach are discussed.

Radiogenic isotopes: the case for crustal recycling on a near-steady-state no-continental-growth Earth

Abstract: Pb, Sr and Nd isotopes define rock ages and residence times in mantle and continental crust, but are not diagnostic of either crustal growth or recycling in a near-steady-state Earth. Constancy of continental freeboard and uniformity of thickness of stable continental crust with age are the only two quantitative measures of crustal volume through time and these imply negligible crustal growth since 2.9 Ga B.P. Planetary analogies, Pb isotopes, atmospheric evolution, and palaeomagnetism also argue for early terrestrial differentiation. Rates of crustal growth and recycling are sufficient to reach a near-steady state over the first 1 Ga of Earth history, before widespread cratonization. Isotope compositions and ages of rocks are quantitatively compatible with near-steady-state recycling involving multiple complete reworkings of the crust by injection into the mantle along subduction zones. The recycling process can be observed to occur on the Earth today. Continental crust is uplifted, reduced in area, and thickened in orogenic belts. It is then subject to erosion, an effective isotopic homogenization process. A fraction of the sediment flux reaches the ocean floor or accumulates along continental margins, while soluble elements and water become fixed in ocean crust and trapped in sediments. Subduction of altered ocean crust, sediment, microcontinents and fragments of basement ripped off the edges of continents completes the process whereby continental crust, enriched in radiogenic Pb and Sr and with relatively unradiogenic Nd, is returned to the mantle. Pb, Sr and Nd isotopic compositions of igneous rocks from the mantle are explainable in terms of a near-steady-state model. The mantle buffer dominates observed isotope Sr and Nd evolutions. Mixing of crust and mantle causes all the isotope evolutions to approximate single-stage growth curves. Isotopic heterogeneity of the Earth increases as the rate of mixing declines. The observed escape of primordial $^{3}$He from the mantle is not evidence for continuing continental differentiation or against early differentiation of the Earth. Even if nearly complete equilibrium chemical differentiation occurred at 4.6 Ga B.P., some $^{3}$He would remain dissolved in the interior and would escape as recycling continued. A true steady state cannot be achieved because the driving energy declines with time and Earth surface processes have evolved with development of life and an oxygenated atmosphere. These unidirectional changes, plus variation in subduction rates and setting and style, and variation in rates of cratonization, provide a complex overprint on the near-steady-state background of continental evolution.

Developmental aspects of cross-language speech perception.

Abstract: Previous research has suggested that infants discriminate many speech sounds according to phonemic category regardless of language exposure, while adults of one language group may have difficulty discriminating nonnative linguistic contrasts. Our study attempted to address directly questions about infant perceptual ability and the possibility of its decline as a function of development in the absence of specific experience by comparing English-speaking adults, Hindi-speaking adults, and 7-month-old infants on their ability to discriminate 2 pairs of natural Hindi (non-English) speech contrasts. To do this, infants were tested in a "visually reinforced infant speech discrimination" paradigm, while a variant of this paradigm was used to test adults. Support was obtained for the above hypotheses. Infants were shown to be able to discriminate both Hindi sound pairs, and support for the idea of a decrease in speech perceptual abilities wih age and experience was clearly evident with the rarer of the 2 non-English contrasts. The results were then discussed with respect to the possible nature and purpose of these abilities.

Efficiency of human visual signal discrimination.

Abstract: We have measured the overall statistical efficiency of human subjects discriminating the amplitude of visual pattern signals added to noisy backgrounds. By changing the noise amplitude, the amount of intrinsic noise can be estimated and allowed for. For a target containing a few cycles of a spatial sinusoid of about 5 cycles per degree, the overall statistical efficiency is as high as 0.7 +/- 0.07, and after correction for intrinsic noise, efficiency reaches 0.83 +/- 0.15. Such a high figure leaves little room for residual inefficiencies in the neural mechanisms that handle these patterns.

Conditioned defensive burying: a new paradigm for the study of anxiolytic agents

Abstract: Behavioral paradigms that have been designed to mimic forms of learning that are important for the survival of animals in the wild, rather than to minimize the contributions of adaptive predispositions, may prove to be particularly useful for studying the behavioral effects of drugs. In the present experiments, the propensity of rats to bury sources of aversive stimulation was disrupted in a dose-dependent fashion by a single injection of the anxiolytic drug, diazepam. This suggested that the conditioned defensive burying paradigm could prove to be a valuable addition to the paradigms available for studying anxiolytic effects. Supporting this view were two additional observations. First, the relative potencies of diazepam, chlordiazepoxide, and pentobarbital in the burying paradigm compared favorably with their relative potencies in clinical settings. Second, the effects of anxiolytics on conditioned burying appeared to be dissociable from the effects of other drugs that disrupt this behavior.

Affective Quality Attributed to Environments: A Factor Analytic Study

Abstract: A set of 105 commonly used adjectives descriptive of the affective quality of molar physical environments was developed and factor analyzed (based on 323 subjects' ratings, each of a different environment). Two, independent, bipolar factors of affective quality-pleasing and arousing quality-were obtained and shown to correlate highly with subjects' affective reactions of pleasure and arousal to the environments. The pleasing and- arousing quality dimensions were hypothesized to summarize the emotive capacity attributed to environments and to adequately define the numerous affective descriptors commonly used: peaceful, festive, hectic, disgusting, boring, and the like. They were also offered as partial interpretations of the semantic differential factors of evaluation and activity, respectively.

Reiter's syndrome. Evaluation of preliminary criteria for definite disease.

Abstract: A retrospective evaluation of 83 patients with Reiter's syndrome (RS) and 166 comparison arthritis patients was conducted in order to assess the preliminary criteria for definite RS. Data analysis was based on the statement that Reiter's syndrome consists of an episode of peripheral arthritis of more than 1 month duration occurring in association with urethritis and/or cervicitis. During the initial episode of RS, 70 of the 83 RS patients satisfied the criteria, yielding a sensitivity of 84.3%.

Minimum cost spanning tree games

Abstract: We consider the problem of cost allocation among users of a minimum cost spanning tree network. It is formulated as a cooperative game in characteristic function form, referred to as a minimum cost spanning tree (m.c.s.t.) game. We show that the core of a m.c.s.t. game is never empty. In fact, a point in the core can be read directly from any minimum cost spanning tree graph associated with the problem. For m.c.s.t. games with efficient coalition structures we define and construct m.c.s.t. games on the components of the structure. We show that the core and the nucleolus of the original game are the cartesian products of the cores and the nucleoli, respectively, of the induced games on the components of the efficient coalition structure.

Hennig's Parasitological Method: A Proposed Solution

Abstract: Brooks, D. R. (Department of Zoology, University of British Columbia, 2075 Wesbrook Mall, Vancouver, B.C., Canada V6T 2A9) 1981. Hennig's parasitological method: a proposed solution. Syst. Zool., 30:229-249.-A quantitative solution for Hennig's parasitological method is presented. Cladograms summarizing natural relationships among parasite taxa are converted into host-group characters by means of additive binary coding. Unrooted Wagner analysis followed by most parsimonious rooting produces a maximum information-content representation of natural host-parasite relationships. Because host-parasite relationships result either from random colonization or from co-speciation, host relationships well corroborated by a multi-parasite analysis correspond to host phylogeny. Poorly corroborated host relationships indicate an ambiguous parasite message alerting a worker to possible host transfers. Thus, such analyses point out co-speciation and random colonization components of host-parasite systems. Single or multiple parasite taxa may be used. A host phylogeny based on non-parasite characters is neither necessary nor sufficient for studying phylogenetic aspects of coevolution, although such may be helpful in testing ambiguous aspects. Once a host-group cladogram based on parasites has been established, phylogenetic interpretations for each observed host-parasite relationship may be made according to a listed set of necessary and sufficient criteria. Finally, evaluation of two models of coevolution, a "vicariance" model and the "resource-tracking" model, indicates that the latter cannot be extrapolated successfully to explain congruent phylogenetic differentiation of hosts and parasites and that the former model represents the general pattern of natural relationships among hosts and parasites. [Cladistics; coevolution; phylogeny; quantitative systematics.]

Slow-reacting substances (leukotrienes) contract human airway and pulmonary vascular smooth muscle in vitro

Abstract: During a type I allergic reaction histamine, slow-reacting substance of anaphylaxis (SRS-A) and other mediator substances are elaborated from specific tissue sites1. In allergic asthma these sites are in the lung and the mediator substances cause airway obstruction by contracting smooth muscle and altering mucociliary function2–4. Unlike histamine, slow-reacting substances (SRSs) have been assessed very little for their roles in obstructive airways disease. This has been partly due to the fact that their chemical nature was unknown until recently and thus pure samples were not available for pharmacological studies. However, SRSs isolated from both immunological and non-immunological reactions have been identified as a combination of two related lipid substances—leukotriene C4 (LTC) and leukotriene D4 (LTD)5,6; thus it is now possible to use pure SRSs (leukotrienes) in pharmacological studies of airway smooth muscle. LTC and LTD have been shown to contract guinea pig tracheal and lung parenchymal strips5 but there is no evidence that these substances produce similar effects on human lung tissue. To clarify this, in vitro pharmacological studies were done to determine the actions of LTC and LTD on smooth muscle strips of human bronchus, pulmonary vein and artery, and lung parenchymal tissue containing smooth muscle components and pleura. As indicated in a preliminary report7, all four types of tissues contracted in a dose-dependent fashion to the leukotrienes, although these substances only function as partial agonists.

On interacting defaults

Abstract: Although most commonly occurring default rules are normal when viewed in isolation, they can interact with each other in ways that lead to the derivation of anomalous default assumptions*. In order to deal with such anomalies it is necessary to re-represent these rules, in some cases by Introducing non-normal defaults. The need to consider such potential interactions leads to a new concept of integrity, distinct from the conventional Integrity Issues of first order data bases. The non-normal default rules required to deal with default interactions all have a common pattern, Default theories conforming to this pattern are considerably more complex than normal default theories. For example, they need not have extensions, and they lack the property of semi-monotonicity.

Postmortem Changes of Amino Compounds in Human and Rat Brain

Abstract: Contents of 35 amino acids and related compounds were measured in whole rat brain, and in superficial areas of biopsied and autopsied human brain, after incubation for various intervals at temperatures simulating those likely to occur in cadavers under mortuary conditions. These data should aid interpretation of values for amino compounds determined in autopsied brain from patients with neurological or psychiatric disorders. The contents of glutamic acid, glutamine, taurine, phosphoethanolamine, cystathionine, and homocarnosine remain unchanged for long periods in human brain. Aspartic acid content is stable for 4 h after death, but thereafter rises rapidly. Glycine content rises rapidly, as do the contents of most amino acid components of proteins. Glutathione content drops rapidly in human brain after death. GABA content is stable for about 30 min, and rises to a maximum 2 to 3 h after death, after which it remains unchanged for at least 24 h. In rat brain, GABA content rises more rapidly, aspartate content rises more slowly, homocarnosine content decreases progressively, and glycerophosphoethanolamine content decreases more rapidly than in human brain.

Efficiency of the Market for Racetrack Betting

Abstract: Many racetrack bettors have systems. Since the track is a market similar in many ways to the stock market one would expect that the basic strategies would be either fundamental or technical in nature. Fundamental strategies utilize past data available from racing forms, special sources, etc. to "handicap" races. The investor then wagers on one or more horses whose probability of winning exceeds that determined by the odds by an amount sufficient to overcome the track take. Technical systems require less information and only utilize current betting data. They attempt to find inefficiencies in the "market" and bet on such "overlays" when they have positive expected value. Previous studies and our data confirm that for win bets these inefficiencies, which exist for underbet favorites and overbet longshots, are not sufficiently great to result in positive profits. This paper describes a technical system for place and show betting for which it appears to be possible to make substantial positive profits and thus to demonstrate market inefficiency in a weak form sense. Estimated theoretical probabilities of all possible finishes are compared with the actual amounts bet to determine profitable betting situations. Since the amount bet influences the odds and theory suggests that to maximize long run growth a logarithmic utility function is appropriate the resulting model is a nonlinear program. Side calculations generally reduce the number of possible bets in any one race to three or less hence the actual optimization is quite simple. The system was tested on data from Santa Anita and Exhibition Park using exact and approximate solutions that make the system operational at the track given the limited time available for placing bets and found to produce substantial positive profits. A model is developed to demonstrate that the profits are not due to chance but rather to proper identification of market inefficiencies.

Effective potential for the order parameter of gauge theories at finite temperature

Abstract: $\mathrm{SU}(n)$ gauge theories at finite temperature $T={\ensuremath{\beta}}^{\ensuremath{-}1}$ are analyzed in terms of the spontaneous breakdown of a $Z(n)$ symmetry corresponding to the order parameter $L(\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}})=(\frac{1}{n})\mathrm{Tr}P\mathrm{exp}[ig\ensuremath{\int}{0}^{\ensuremath{\beta}}{A}_{0}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}},t)dt]$. An "effective potential" for $L$ is evaluated in the one-loop approximation for both the continuum and the lattice gauge theories. It is shown that the $Z(n)$ symmetry is broken, so that the continuum theory does not confine for high temperatures. Similarly the lattice theory does not confine for sufficiently weak coupling if the number of time sites ${N}_{t}$ is finite. It is argued that as ${N}_{t}\ensuremath{\rightarrow}\ensuremath{\infty}$ the $Z(n)$ symmetry is restored and the theory will confine for all values of the coupling.

Principles of feature integration in visual perception

Abstract: Several recent theories of visual information processing have postulated that errors in recognition may result not only from a failure in feature extraction, but also from a failure to correctly join features after they have been correctly extracted. Errors that result from incorrectly integrating features are called conjunction errors. The present study uses conjunction errors to investigate the principles used by the visual system to integrate features. The research tests whether the visual system is more likely to integrate features located close together in visual space (the location principle) or whether the visual system is more likely to integrate features from stimulus items that come from the same perceptual group or object (the perceptual group principle). In four target-detection experiments, stimuli were created so that feature integration by the location principle and feature integration by the perceptual group principle made different predictions for performance. In all of the experiments, the perceptual group principle predicted feature integration even though the distance between stimulus items and retinal eccentricity were strictly controlled.

Cloudy bag model of the nucleon

Abstract: A previously derived model in which a baryon is treated as a three-quark bag that is surrounded by a cloud of pions is used to compute the static properties of the nucleon. The only free parameter of the model is the bag radius which is fixed by a fit to pion-nucleon scattering in the (3,3)-resonance region to be about 0.8 fm. With the model so determined the computed values of the root-mean-square radii and magnetic moments of the neutron and proton, and ${g}_{A}$, are all in very good agreement with the experimental values. In addition, about one-third of the $\ensuremath{\Delta}$-nucleon mass splitting is found to come from pionic effects, so that our extracted value of ${\ensuremath{\alpha}}_{s}$ is smaller than that of the MIT bag model.