Showing papers by "University of Toronto published in 1980"

Heuristic versus systematic information processing and the use of source versus message cues in persuasion.

Abstract: In Experiment 1, subjects read a persuasive message from a likable or unlikable communicator who presented six or two arguments concerning one of two topics. High response involvement subjects anticipated discussing the message topic at a future experimental session, whereas low involvement subjects anticipated discussing a different topic. For high involvement subjects, opinion change was significantly greater given six arguments but was unaffected by communicator likability. For low involvement subjects, opinion change was significantly greater given a likable communicator but was unaffected by the arguments manipulation. In Experiment 2, high issue involvement subjects showed slightly greater opinion change when exposed to five arguments from an unlikable (vs. one argument from a likable) communicator, whereas low involvement subjects exhibited significantly greater persuasion in response to one argument from a likable (vs. five arguments from an unlikable) communicator. These findings support the idea that high involvement leads message recipients to employ a systematic information processing strategy in which message-based cognitions mediate persuasion, whereas low involvement leads recipients to use a heuristic processing strategy in which simple decision rules mediate persuasion. Support was also obtained for the hypothesis that content-mediated (vs. source-mediated) opinion change would shower greater persistence.

Socio-cultural factors in the development of anorexia nervosa

Abstract: A population of professional dance (N = 183) and modelling (N = 56) students, who by career choice must focus increased attention and control over their body shapes, was studied. Height and weight data were obtained on all subjects. In addition, a questionnaire that is useful in assessing the symptoms of anorexia nervosa, the Eating Attitudes Test (EAT), was administered. Results of these tests were compared with those of normal female university students (N = 59), patients with anorexia nervosa (N = 68), and music students (N = 35). Anorexia nervosa and excessive dieting concerns were overrepresented in the dance and modelling students. Twelve cases (6.5%) of primary anorexia nervosa were detected in the dance group. All but one case developed the disorder while studying dance. Within the dance group those from the most competitive environments had the greatest frequency of anorexia nervosa. These data suggest that both pressures to be slim and achievement expectations are risk factors in the development of anorexia nervosa. The influence of socio-cultural determinants are discussed within the context of anorexia nervosa as a multidetermined disorder.

The sequential analysis of cancer development.

Abstract: Publisher Summary This chapter reviews the sequence of cellular and other changes during cancer development in selected sites in experimental animals and in humans. It highlights the similarities and differences among the carcinogenic processes and discusses the evident generalities and working hypotheses derived from the analyses. It also discusses some perspective concerning the possible relationship of carcinogenesis to other types of chronic pathological processes such as some forms of adaptation and evolution. Major emphasis is given to three sites—namely, skin, liver, and breast. Several other sites or types of neoplasms are also discussed in the chapter, including urinary bladder, brain, kidney, uterine cervix, and foreign-body sarcoma. It focuses on the development of cancer with chemicals in experimental animals and in humans. To date, the major evidence for a beneficial role for new cell populations occurring during the preneoplastic phase of carcinogenesis concerns the liver. However, it seems appropriate to explore other systems from this point of view. In other organs or tissues, appropriate physiological or environmental factors should be sought as possible influences on early carcinogen-induced new cell populations. These influences might well constitute naturally occurring “promoting” environments in at least some carcinogenic process.

A language facility for designing database-intensive applications

Abstract: TAXIS, a language for the design of interactive information systems (e.g., credit card verification, student-course registration, and airline reservations) is described. TAXIS offers (relational) database management facilities, a means of specifying semantic integrity constraints, and an exception-handling mechanism, integrated into a single language through the concepts of class, property, and the IS-A (generalization) relationship. A description of the main constructs of TAXIS is included and their usefulness illustrated with examples.

The cue-dependent nature of state-dependent retrieval

Abstract: An enduring problem in the study of human state-dependent retrieval concerns the apparent unpredictability of the phenomenon. Although many investigators have observed that utilization of information in episodic memory critically depends for its success on restoration, at the time of attempted retrieval, of the pharmacological state in which the information was originally acquired, many others have been unable to find evidence of such state-dependent effects. Indeed, negative results are so common that human state dependence has come to be popularly regarded as an untrustworthy phenomenon of little practical or theoretical significance. The message of this article is that the unpredictability of state-dependent effects in man is more apparent than real. Evidence is presented to the effect that, with very few exceptions, failures to demonstrate state dependence are restricted to situations in which utilization of stored information is tested in the presence of discretely identifiable retrieval cues, and successes, to situations in which retrieval occurs in the absence of any observable reminders. It is also shown that when the conditions of retrieval, with respect to the presence or absence of explicit cues, remain constant, the probability of demonstrating state dependence also remains constant across a relatively broad spectrum of experimental conditions. Speculations about the nature of the cognitive mechanisms underlying the so-called “cuing effect” in human state dependence are offered, and promising new directions for research are outlined.

Disease-induced Changes in the Plasma Binding of Basic Drugs

Abstract: The plasma binding of basic (cationic) drugs differs from that of the more completely studied acidic drugs. Basic drugs associate with a number of plasma constituents. alpha 1-Acid glycoprotein, lipoprotein, and albumin all appear to play an important role in the binding of most of these drugs. Acidic drugs bind largely to albumin. The variation in plasma albumin is relatively narrow and is almost always in the direction of decreased concentrations. alpha 1-Acid glycoprotein and lipoproteins show large fluctuations due both to physiological and pathological conditions. Decreases and increases in concentration have been observed. Associated with these changes in binding proteins, both decreases and increases in plasma binding of basic drugs have been recorded. Increased binding with disease appears to be virtually unique to basic drugs. The implications of these newly described disease-induced increases in plasma binding have yet to be explored. With the limited information in hand the following consequences are predicted. Increased binding will tend to decrease the volume of distribution of total (bound plus free) drug. The clearance will be unchanged or decreased depending upon the initial clearance of the drug and the avidity of the protein binding. As the half-life depends upon both clearance and volume of distribution, changes in it will be variable, depending upon changes in these two parameters. It is predicted that the area under the free drug plasma concentration-time curve will decrease with increasing binding after an intravenous dose while it will be unchanged after an oral dose. The relationship of total drug plasma concentration to free drug concentration will change with changes in binding. Thus plasma concentration monitoring of drug therapy by use of total drug concentrations will be inaccurate in situations in which large variations in binding occur. Misinterpretations of both therapeutic monitoring and pharmacokinetics studies in disease states with altered binding are likely unless these changes are appreciated.

Strength and ductility of tied concrete columns

Abstract: Short 12-in. (305 mm) square concrete columns with rectangular ties as confinement steel are tested under monotonic axial compression to failure. Land-deformation curves are presented. Contribution of concrete to load carrying capacity and the significance of cover spalling are examined. Effects of distribution of longitudinal steel around the column perimeter and the resulting tie configuration, the amount and characteristics of tie steel, tie spacing, and the amount of longitudinal steel affecting the behavior of the confined column core are examined. Concrete cores of columns confined with ties and well distributed longitudinal steel exhibit significant gain in strength and ductility. Tie spacing and the characteristics and the amount of tie steel significantly affect the strength and ductility of confined core. The amount of column steel does not appear to have significant effect on confinement.

Tracing the time course of picture--word processing.

Abstract: A number of independent lines of research have suggested that semantic and articulatory information become available differentially from pictures and words. The first of the experiments reported here sought to clarify the time course by which information about pictures and words becomes available by considering the pattern of interference generated when incongruent pictures and words are presented simultaneously in a Stroop-like situation. Previous investigators report that picture naming is easily disrupted by the presence of a distracting word but that word naming is relatively immune to interference from an incongruent picture. Under the assumption that information available from a completed process may disrupt an ongoing process, these results suggest that words access articulatory information more rapidly than do pictures. Experiment 1 extended this paradigm by requiring subjects to verify the category of the target stimulus. In accordance with the hypothesis that picture access the semantic code more rapidly than words, there was a reversal in the interference pattern: Word categorization suffered considerable disruption, whereas picture categorization was minimally affected by the presence of an incongruent word. Experiment 2 sought to further test the hypothesis that access to semantic and articulatory codes is different for pictures and words by examining memory for those items following naming or categorization. Categorized words were better recognized than named words, whereas the reverse was true for pictures, a result which suggests that picture naming involves more extensive processing than picture categorization. Experiment 3 replicated this result under conditions in which viewing time was held constant. The last experiment extended the investigation of memory differences to a situation in which subjects were required to generate the superordinate category name. Here, memory for categorized pictures was as good as memory for named pictures. Category generation also influenced memory for words, memory performance being superior to that following a yes--no verification of category membership. These experiments suggest a model of information access whereby pictures access semantic information were readily than name information, with the reverse being true for words. Memory for both pictures and words was a function of the amount of processing required to access a particular type of information as well as the extent of response differentiation necessitated by the task.

Household production and the national economy: Concepts for the analysis of Agrarian formations

Abstract: This essay argues that the central concept for analysis of agrarian social relations is the form of production. This is conceived through a double specification of the unit of production and the social formation. The approach allows for the analytical specification of simple commodity production and capitalist relations of production in a manner consistent with the development of new concepts within political economy for agrarian structures which do not correspond to modes of production. The latter have generally been referred to as ‘peasant’, a term derived through empirical generalisation and resting on a (usually) implicit contrast with simple commodity production. The contrast can be made more rigorous through the concept of commoditisation, defined as the penetration into reproduction of commodity relations. Simple commodity production is a concept within political economy, allowing for deduction of conditions of reproduction and class relations. ‘Peasant production is negatively defined as resisting...

Pollen carryover, nectar rewards, and pollinator behavior with special reference to Diervilla lonicera.

Abstract: Pollen carryover was measured in three species of bumble bee pollinated plants by counting the numbers of foreign grains applied to the stigmas of a series of flowers by bumble bees. Deposition declined with the number of flowers visited in a roughly exponential fashion; most grains were deposited on the first few flowers, but some grains went much farther, the maximum carryover being 54 flowers. Variation in deposition was very high. In Diervilla lonicera, bees desposited significantly more grains on flowers which contained large amounts of nectar than on drained flowers. The implications are discussed in terms of plant strategies for optimizing pollination.

A plan-based analysis of indirect speech acts

Abstract: We propose an account of indirect forms of speech acts to request and inform based on the hypothesis that language users can recognize actions being performed by others, infer goals being sought, and cooperate in their achievement. This cooperative behaviour is independently motivated and may or may not be intended by speakers. If the hearer believes it is intended, he or she can recognize the speech act as indirect; otherwise it is interpreted directly. Heuristics are suggested to decide among the interpretations.

Stochastic Simulation of Temperature Effects on First-Year Survival of Smallmouth Bass

Abstract: The physiological basis for well-known correlations between summer air temperature indices and year-class strength in northern smallmouth bass (Micropterus dolomieui) populations was examined. Field and laboratory studies demonstrated the existence of two critical stages in early life when smallmouth bass are particularly vulnerable to features characteristic of many natural water temperature regimes. The first stage extends from fertilization until the young leave the nest; high mortality results from exposure to extreme temperatures. The second stage extends over the first winter, when the young subsist on accumulated energy reserves. Because the ratio of energy stored to basal metabolic rate increases with size, large fish can withstand winter starvation better than small fish. The results from these and other studies were incorporated into a deterministic model of the relations between temperature and first-year survival of small-mouth bass. Analysis of water temperature time series data from...

Ecological and evolutionary significance of mycorrhizal symbioses in vascular plants (A Review).

Abstract: MYCORRHIZAE, THE SYMBIOSES BETWEEN FUNGI AND PLANT ROOTS, ARE NEARLY UNIVERSAL IN TERRESTRIAL PLANTS AND CAN BE CLASSIFIED INTO TWO MAJOR TYPES: endomycorrhizae and ectomycorrhizae. About four-fifths of all land plants form endomycorrhizae, whereas several groups of trees and shrubs, notably Pinaceae, some Cupressaceae, Fagaceae, Betulaceae, Salicaceae, Dipterocarpaceae, and most Myrtaceae form ectomycorrhizae. Among legumes, Papilionoideae and Mimosoideae have endomycorrhizae and usually form bacterial nodules. The members of the third subfamily, Caesalpinioideae, rarely form nodules, and one of the included groups, the two large, pantropical, closely related tribes Amherstieae and Detarieae, regularly form ectomycorrhizae. Nodules and ectomycorrhizae may well be alternative means of supplying organic nitrogen to the plants that form them.Those plants having endomycorrhizae usually occur in forests of high species richness, whereas those with ectomycorrhizae usually occur in forests of low species richness. The roots of ectomycorrhizal trees, however, support a large species richness of fungal symbionts, probably amounting to more than 5000 species worldwide, whereas those of endomycorrhizal trees have low fungal species richness, with only about 30 species of fungi known to be involved worldwide. Ectomycorrhizal forests are generally temperate or occur on infertile soils in the tropics. They apparently have expanded in a series of ecologically important events through the course of time from the Middle Cretaceous onward at the expense of endomycorrhizal forests.

Tobacco Use, Occupation, Coffee, Various Nutrients, and Bladder Cancer

Abstract: In a Canadian population-based case-control study of 480 males and 152 female case-control pairs, the relative risk for development of bladder cancer for ever used versus never used cigarettes was 3.9 for males and 2.4 for females, with a dose-response relationship in both sexes. A reduced risk was associated with the use of filter cigarettes compared to nonfilter cigarettes. After control for cigarette usage, a significant risk was noted for male pipe smokers. For male ex-smokers the risk after 15 years of no smoking was less than one-half that of current male smokers. Bladder cancer risk was found for workers in the chemical, rubber, photographic, petroleum, medical, and food processing industries among males and for workers occupationally exposed to dust or fumes among both sexes. Bladder cancer risk was elevated for males consuming all types of coffee, regular coffee, and instant coffee and for females consuming instant coffee, but no dose-response relationship was found. Risk was found for males consuming water from nonpublic supples but not for females. No risk was observed in males or females consuming nitrate-containing foods, beverages other than coffee, or fiddlehead greens. Hair dye usage in females and phenacetin usage in males and females carried no risk. Divergent findings by area for aspirin suggested that an overall association was not causal. Reevaluation of the data on artificial sweeteners confirmed a significant bladder cancer risk in males and a dose-response relationship. The cumulated population attributable risk for bladder cancer was 90% for males from cigarette smoking, industrial exposure, and exposure to nonpublic water supplies and 29% for females from cigarette smoking, industrial exposure, and instant coffee consumption.

Foraging strategies of Drosophila melanogaster: a chromosomal analysis.

Abstract: Two larval foraging strategies inDrosophila melanogaster were identified, “rover” and “sitter.” “Rovers” traverse a large area while feeding whereas “sitters” cover a small area. The difference between “rovers” and “sitters” was analyzed genetically by chromosomal substitutions between isogenic stocks. Differences in larval locomotor behavior (“crawling behavior”) can be attributed to the second chromosome, the “rover” strategy being dominant over the “sitter” strategy. Differences in feeding rate (“shoveling behavior”) are affected additively by both the second and third chromosomes. Natural populations ofDrosophila larvae were sampled three times over a 2-month period; “rovers” and “sitters” were at constant frequencies in these populations. The two foraging strategies are discussed in the light of resource utilization in environments where food is distributed continuously or discontinuously.

Platinum metals magmatic sulfide ores.

Abstract: Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and fractional segregation of sulfides. The Republic of South Africa and the U.S.S.R. together possess more than 97 percent of the world PGE reserves, but significant undeveloped resources occur in North America. The Stillwater complex in Montana is perhaps the most important example.

CW autocorrelation measurements of picosecond laser pulses

Abstract: Completely general and novel expressions are presented for n th-order fast or slow correlation functions, with or without background contributions, from which more specialized n th- and second-order auto-correlation functions are derived A straightforward method for obtaining CW autocorrelation measurements of picosecond pulses is then described which employs an audio loudspeaker driven at 30 Hz in one arm of the correlator to permit autocorrelation display at this frequency Results of the application of this device to measurements of the picosecond pulses from a CW synchronously mode-locked Rhodamine 6G dye laser are presented

Analysis of second-harmonic generation at metal surfaces

Abstract: We discuss the second-harmonic generation of light at metal surfaces within the hydrodynamic theory of the electron gas; expressions for the phenomenological parameters $a$ and $b$ of Rudnick and Stern are presented, and the possibility of a resonance in $a$ at optical or near-uv frequencies is discussed. A recent plasmon-enhanced experiment of Simon et al. is analyzed, and the use of such experiments to determine $a$ and $b$ is considered; new experiments are proposed to aid in such a determination.

A case-control study of diet and colo-rectal cancer.

Abstract: A case-control study of cancer of the colon and rectum has been conducted in Calgary, Alberta and Toronto, Ontario, Canada. A total of 348 cases of cancer of the colon and 194 cases of cancer of the rectum were individually matched by age, sex and neighbourhood of residence to 542 population controls and frequency matched to 535 hospital controls who had undergone an abdominal operation. Each subject received a personal medical history questionnaire and a quantitative diet history questionnaire. Data on a number of potential non-nutrient risk factors for bowel cancer and on the consumption of 9 nutrients in the 2-month period up to 6 months before interview were analysed. The dietary data thus refer to recent diet consumed in a period antedating the diagnosis of, and in most cases symptoms from, large-bowel cancer in the cases, and a corresponding time period in the controls. The major findings were an elevated risk for those with a history of bowel polyps, and for those with an elevated intake of calories, total fat, total protein, saturated fat, oleic acid and cholesterol. No association was seen with an elevated intake of crude fibre, Vitamin C and linoleic acid. The nutrients for which an increased risk was demonstrated were highly correlated, though multivariate analysis using logistic regression indicated highest risk for saturated fat, with evidence of a dose-response relationship. The findings in both cancer sites, both sexes and with both sets of controls were quantitatively very similar. The population-attributable risk for colon and rectal cancer combined was estimated from the neighbourhood controls to be 41% for males and 44% for females for saturated fat intake and 9.8% and 6.4% respectively for any history of polyps.

Models for Understanding Flexible Manufacturing Systems

Abstract: The basic features of flexible manufacturing systems are reviewed and models for determining the production capacity of such systems are developed. These models show the desirability of a balanced work load, the benefit of diversity in job routing if there is adequate control of the release of jobs (a job shop can be better than a flow shop), and the superiority of common storage for the system over local storage at machines. The models are extended to allow for material handling delays between machines and for unreliable machines. It is also shown that production capacity models can be used to develop good approximations to the mean number of jobs in the system for given job arrival rates and machine utilizations.