Showing papers by "York University published in 1991"

Strategic responses to institutional processes

Abstract: This article applies the convergent insights of institutional and resource dependence perspectives to the prediction of strategic responses to institutional processes. The article offers a typology of strategic responses that vary in active organizational resistance from passive conformity to proactive manipulation. Ten institutional factors are hypothesized to predict the occurrence of the alternative proposed strategies and the degree of organizational conformity or resistance to institutional pressures.

Lexical cohesion computed by thesaural relations as an indicator of the structure of text

Abstract: In text, lexical cohesion is the result of chains of related words that contribute to the continuity of lexical meaning. These lexical chains are a direct result of units of text being "about the same thing," and finding text structure involves finding units of text that are about the same thing. Hence, computing the chains is useful, since they will have a correspondence to the structure of the text. Determining the structure of text is an essential step in determining the deep meaning of the text. In this paper, a thesaurus is used as the major knowledge base for computing lexical chains. Correspondences between lexical chains and structural elements are shown to exist. Since the lexical chains are computable, and exist in non-domain-specific text, they provide a valuable indicator of text structure. The lexical chains also provide a semantic context for interpreting words, concepts, and sentences.

Some differences make a difference: Individual dissimilarity and group heterogeneity as correlates of recruitment, promotions, and turnover.

Abstract: Schneider's (1987) attraction-selection-attrition model and Pfeffer's (1983) organization demography model were used to generate individual-level and group-level hypotheses relating interpersonal context to recruitment, promotion, and turnover patterns. Interpersonal context was operationalized as personal dissimilarity and group heterogeneity with respect to age, tenure, education level, curriculum, alma mater, military service, and career experiences. For 93 top management teams in bank holding companies examined over a 4-yr period, turnover rate was predicted by group heterogeneity. For individuals, turnover was predicted by dissimilarity to other group members, but promotion was not. Team heterogeneity was a relatively strong predictor of team turnover rates. Furthermore, reliance on internal recruitment predicted subsequent team homogeneity.

Micronuclei as an index of cytogenetic damage: Past, present, and future

Abstract: The workshop was designed to present what is known about the production of micronuclei, what protocols are now accepted or proposed internationally, what new results have been obtained, and what new methods and protocols are likely to be forthcoming. This report is designed to convey the flavour of the workshop and to provide the essence of the new information. After the workshop an effort was made to determine what single protocol would satisfy the requirements set for the micronucleus test by as many regulatory agencies as possible. The result, reported here, includes the requirements of six regulatory authorities in Canada, the European Economic Community, the Organization for Economic Co-operation and Development, Japan, and the United States.

Victims and Shareholders: The Dilemmas of Presenting Corporate Policy During A Crisis

Abstract: Corporate crises—such as accidents, scandals, and product safety incidents—exacerbate stakeholder demands in such a way that conflict can arise between the interests of shareholders and crisis vict

Phase-based disparity measurement

Abstract: The measurement of image disparity is a fundamental precursor to binocular depth estimation. Recently, Jenkin and Jepson (in Computational Processes in Human Vision (V. Pylyshyn, Ed.), Ablex, New Jersey, 1988) and Sanger (Biol. Cybernet, 59, 1988 , 405–418) described promising methods based on the output phase behavior of bandpass Gabor filters. Here we discuss further justification for such techniques based on the stability of bandpass phase behavior as a function of typical distortions that exist between left and right views. In addition, despite this general stability, we show that phase signals are occasionally very sensitive to spatial position and to variations in scale, in which cases incorrect measurements occur. We find that the primary cause for this instability is the existence of singularities in phase signals. With the aid of the local frequency of the filter output (provided by the phase derivative) and the local amplitude information, the regions of phase instability near the singularities are detected so that potentially incorrect measurements can be identified. In addition, we show how the local frequency can be used away from the singularity neighbourhoods to improve the accuracy of the disparity estimates. Some experimental results are reported.

Robotic exploration as graph construction

Abstract: Addressed is the problem of robotic exploration of a graphlike world, where no distance or orientation metric is assumed of the world. The robot is assumed to be able to autonomously traverse graph edges, recognize when it has reached a vertex, and enumerate edges incident upon the current vertex relative to the edge via which it entered the current vertex. The robot cannot measure distances, and it does not have a compass. It is demonstrated that this exploration problem is unsolvable in general without markers, and, to solve it, the robot is equipped with one or more distinct markers that can be put down or picked up at will and that can be recognized by the robot if they are at the same vertex as the robot. An exploration algorithm is developed and proven correct. Its performance is shown on several example worlds, and heuristics for improving its performance are discussed. >

A Theory of If: A Lexical Entry, Reasoning Program, and Pragmatic Principles

Abstract: The theory has 3 parts: (a) A lexical entry defines the information about if in semantic memory; its core comprises 2 inferences schemas, Modus Ponens and a schema for Conditional Proof; the latter operates under a constraint that explains differences between if and the material conditional of standard logic. (b) A propositional-logic reasoning program specifies a routine for reasoning from information as interpreted to a conclusion. (c) A set of pragmatic principles governs how an if sentence is likely to be interpreted in context

Social Relationships, Personality, and Anxiety During a Major Stressful Event

Abstract: Although it is commonly believed that social relationships buffer the effects of stress on mental health, these apparent buffering effects may be spurious reflections of personality or prior mental health. This possibility was investigated in a prospective study of a medical school entrance examination. Five weeks before the examination, Ss (N = 56) rated their personality (extraversion and neuroticism) and social relationships (number of social contacts and perceived support). They then rated their anxiety for 35 days surrounding the examination. Controlling for personality and prior anxiety, social contacts buffered against increases in anxiety, whereas perceived support did not. Further analyses revealed that discretionary social contacts were beneficial whereas obligatory contacts were not. It is now commonly believed that social relationships buffer the effects of stress on mental health. Although this belief is grounded in more than a decade of research (S. Cohen & Syme, 1985; B. R. Sarason, Sarason, & Pierce, 1990), some commentators have argued that the stress-buffering effects of social relationships may reflect personal rather than environmental resources (e.g., Gottlieb, 1983; Hansson, Jones, & Carpenter, 1984; Heller, 1979; Thoits, 1982). Bolstering this claim is evidence that people's perceptions of social support are confounded with both their personality (Henderson, Byrne, & Duncan-Jones, 1981) and their prior mental health (Monroe, Bromet, ConneU, & Steiner, 1986; Turner, 1981). Although contrary findings also exist (e.g., S. Cohen, Sherrod, & Clark, 1986), the possibility that social support effects are spurious remains a serious threat to the validity of this area of research. Two issues have hampered the resolution of this question; one is conceptual and the other is methodological. At the conceptual level, the literature has neglected structural and interactional features of relationships, such as network size and frequency of social contacts (Coyne & Bolger, 1990; House & Kahn, 1985). Thus, research showing the confounding effects of personality and prior mental health is based on perceived support measures of social relationships. We will argue that perceptions of support are more prone to these confounding effects than are structural and interactional measures. At the methodological level, it is a major drawback that most existing social support research has used weak, cross-sectional, and retrospective designs (Monroe & Steiner, 1986). Such designs are unsuitable for determining the causal role of social relationships in adaptation to stress. In this study, we sought to

Construction and beam test of the ZEUS forward and rear calorimeter

Abstract: The forward and rear calorimeters of the ZEUS experiment are made of 48 modules with maximum active dimensions of 4.6 m height, 0.2 m width, 7 λ depth and maximum weight of 12 t. It consists of 1 X 0 uranium plates interleaved with plastic scintillator tiles read out via wavelength shifters and photomultipliers. The mechanical construction, the achieved tolerances as well as the optical and electronics readout are described. Ten of these modules have been tested with electrons, hadrons and muons in the momentum range 15–100 GeV/ c . Results on resolution, uniformity and calibration are presented. Our main result is the achieved calibration accuracy of about 1% obtained by using the signal from the uranium radioactivity.

Integrating formal and functional approaches to language teaching in French immersion : An experimental study

Abstract: This experimental study was designed to evaluate the effect on French language proficiency of an integrated formal, analytic and functional, communicative approach (experiential) to second-language teaching in the immersion classroom. The impetus for the study arises from previous research indicating that immersion children show persistent weaknesses in their grammatical skills despite the fluent, functional proficiency they achieve in their second language. The experimental materials, which were custom-designed for our study, highlight form-function relations, promote noticing, encourage metalin-guistic awareness, and provide opportunities for language practice and thus relate to some of the theoretical issues that Rod Ellis (this volume) has indicated are important in SLA in the 90s. This classroom-based study on the conditional is one of a series of studies undertaken in Canadian French immersion to investigate the effectiveness of form-focused instruction in classrooms (see Swain, 2000). The results of our study, which was conducted in grade 7 early immersion, showed that the Experimental group performed significantly higher in writing than the Control group, in both the post- and the follow-up testing. Although this was not found for speaking, an examination of the individual class data revealed greater and more consistent growth in speaking for the Experimental than for the Control classes, suggesting that they benefited somewhat from the experi- mental treatment in this domain as well. Although Ellis (this volume) notes that research on form-focused instruc- tion in the 90s has tended to split pedagogy from theory, the immersion research in this area does not seem t o reflect this shift. In a recent article, Swain (2000) reviews the French Immersion (FI) studies and summarizes their re- sults as follows: “Overall, the set of experiments conducted in FI classes suggest that there is value in focusing on language form through the use of pre-planned curriculum materials in the context of content-based language learn- ing” (Swain, 2000, p. 205). Her reference to curriculum materials and to the specific context of content-based lan- guage learning should signal to the reader the orientation t o pedagogical considerations that characterize this research. As Ellis notes, hybrid research using both experimental and qualitative methods is becoming more common in SLA. Recently, the experimental materials in our study were implemented in a grade 8 immersion classroom, and the children's collaborative language activity was observed by a researcher working from a sociocultural theoretical per- spective (Spielman-Davidson, 2000). The uptake of our research by a researcher working in another paradigm introduces another kind of hybridity that we hope will also shed further light on questions in form-focused instruction and lead to appropriate changes in pedagogy and in the design of immersion curricula.

Predicting employment in traumatic brain injury following neuropsychological rehabilitation

Abstract: Employment outcome was predicted for fifty-nine clients with traumatic brain injury participating in a holistic neuropsychological rehabilitation program using data collected prior to and following treatment. Group process measures and staff ratings were added to demographic, neurological, and psych

Research on the process of change

Abstract: This paper explores some of the principles involved in the shift toward the study of change events in psychotherapy. A process-analytic approach to the study of change is suggested aimed at the development of micro-theory to explain the change processes that occur in specific in therapy contexts. It is suggested that designs which relate these complex change process to outcome will help determine which factors within a treatment model explain the obtained outcomes.

Congestive heart failure, coronary events and atherothrombotic brain infarction in elderly blacks and whites with systemic hypertension and with and without echocardiographic and electrocardiographic evidence of left ventricular hypertrophy.

Abstract: Hypertension was present in 50% of 196 blacks and in 36% of 382 whites (p less than 0.001). A prospective study of 84 elderly blacks (70% women) and 326 elderly whites (73% women) with hypertension correlated echocardiographic and electrocardiographic left ventricular (LV) hypertrophy with incidences of congestive heart failure (CHF), coronary events and atherothrombotic brain infarction (ABI). Echocardiographic LV hypertrophy (p less than 0.02) and concentric LV hypertrophy (p less than 0.001) were more prevalent in hypertensive blacks than in hypertensive whites. Hypertensive blacks were younger (78 +/- 9 years) than hypertensive whites (82 +/- 7 years) (p less than 0.001). Other coronary risk factors were similar, except for higher serum triglycerides in whites than in blacks (p less than 0.02). Follow-up was 37 +/- 18 months in blacks and 43 +/- 18 months in whites (p less than 0.01). Incidences of CHF and coronary events were not significantly different in blacks and whites. ABI incidence was 38% in blacks and 21% in whites (p less than 0.005). Multiple logistic regression analysis showed that prior CHF (p = 0.000), concentric LV hypertrophy (p = 0.018) and echocardiographic LV hypertrophy (p = 0.022) were independent risk factors for CHF. Echocardiographic LV hypertrophy (p = 0.001), serum total cholesterol (p = 0.002), concentric LV hypertrophy (p = 0.005) and prior coronary artery disease (p = 0.042) were independent risk factors for coronary events. Prior ABI (p = 0.001), echocardiographic LV hypertrophy (p = 0.001) and electrocardiographic LV hypertrophy (p = 0.034) were independent risk factors for ABI.

Dimensions of perfectionism and irrational thinking

Abstract: Several authors have suggested that perfectionism is associated with irrational thinking. The purpose of the present research was to test the hypothesis that various dimensions of perfectionism are related significantly to core irrational beliefs. In Study 1, 102 subjects completed the Multidimensional Perfectionism Scale (MPS) and the Irrational Beliefs Test (IBT). The MPS provides assessments of self-oriented, other-oriented, and socially prescribed perfectionism. Analyses revealed that self-oriented perfectionism was correlated positively with the IBT high self-expectations and perfect solutions subscales. Socially prescribed perfectionism was correlated significantly with a variety of irrational beliefs including high self-expectations, demand for social approval, dependency, blame proneness, and anxious overconcern. Other-oriented perfectionism was correlated with few irrational beliefs. In Study 2, 130 subjects completed the MPS and the Survey of Personal Beliefs, a new measure of core irrational beliefs. Analyses confirmed that all three perfectionism dimensions were associated with core irrational beliefs. It is concluded that the results constitute general support for the hypothesis that cognitive aspects are important in both personal and social components of perfectionism and that perfectionists are characterized by increased levels of irrational beliefs that may contribute to maladjustment. The findings are discussed in terms of the associations among perfectionism, irrational beliefs, and maladjustment.

Anterior cruciate ligament reconstruction without drill holes.

Abstract: Anterior cruciate ligament (ACL) reconstruction in adolescents with open physes remains a difficult problem for the orthopedic surgeon, especially in view of growing teenage participation in contact sports. Traditionally, treatment of ACL tears in adolescents has been conservative; the patient is advised to delay surgery up to several years for fear of damaging physes by drilling holes across them. Unfortunately, this waiting period may inflict irreparable knee damage. This paper suggests an ACL reconstruction technique that utilizes no drill holes, thus causing no harm to physes or other essential knee structures. A graft consisting of semitendinosus and gracilis (SG) tendons is passed under the anterior horn of the medial meniscus through the knee joint, then brought out through the posterior capsule and secured to the lateral femoral metaphysis. The graft is augmented with an iliotibial band tenodesis. Designed primarily but not exclusively for teenagers with open physes, the procedure has produced encouraging results thus far in a small series.

The Spanish Version Parenting Stress Index: A Psychometric Study

Abstract: Evaluated the psychometric properties of the Spanish version of the Parenting Stress Index (PSI), based on the responses of 223 Hispanic mothers. Alpha coefficients were comparable to those for the original PSI. A factor analysis of the 13 PSI subscales indicated that three factors rather than the original two-factor solution more meaningfully described the Hispanic data. This study is consistent with recent research with Anglo-American mothers suggesting that the dimensions of the PSI are better described by three factors: Child Characteristics, Parent Characteristics, and Child-Parent Interaction. Multivariate analysis of variance (MANOVA) indicated that in a Hispanic sample, mothers of handicapped children reported more parenting stress than mothers of nonhandicapped children. This study supports the cross-cultural utility of the PSI.

Techniques for disparity measurement

Abstract: Many different approaches have been suggested for the measurement of structure in space from spatially separated cameras. In this report we critically examine some of these techniques. Through a series of examples we show that none of the current mechanisms of disparity measurement are particularly robust. By considering some of the implications of disparity in the frequency domain, we present a new definition of disparity that is tied to the interocular phase difference in bandpass versions of the monocular images. Finally, we present a new technique for measuring disparity as the local phase difference between bandpass versions of the two images, and we show how this technique surmounts some of the difficulties encountered by current disparity detection mechanisms.

Effect of fluconazole on the disposition of phenytoin

Abstract: In a randomized, placebo-controlled, parallel study, phenytoin was given in the presence and absence of fluconazole. Twenty healthy male subjects received phenytoin, 200 mg orally, on study days 1 to 3 and 18 to 20 and 250 mg intravenously on study days 4 and 21. Ten subjects received fluconazole, 200 mg orally, and 10 received placebo daily on study days 8 to 21. Serial blood samples were collected during a 24-hour period after the intravenous phenytoin dose. Fluconazole trough concentrations were determined on days 14, 18, and 21. Serum phenytoin area under the concentration-time curve from 0 to 24 hours increased 75% and minimum plasma drug concentration increased 128% after administration of fluconazole, 200 mg/day, for 14 days. These values were significantly greater than the 5% increase in area under the concentration-time curve from 0 to 24 hours and 11.6% increase in minimum plasma drug concentration in the placebo group. Fluconazole trough concentrations remained unchanged during the coadministration of phenytoin. The increased phenytoin concentrations in the presence of fluconazole suggest that fluconazole inhibits phenytoin metabolism. Serum concentration monitoring with a reduction in phenytoin dosage is clinically warranted in patients receiving phenytoin and concomitant fluconazole therapy.

Visually-induced sickness in normal and bilaterally labyrinthine-defective subjects.

Abstract: A group of nine normal subjects (with no overt vestibular dysfunction) and a group of 6 bilaterally labyrinthine-defective subjects were exposed to a visual field rotating about an Earth-horizontal axis (orthogonal to the gravity axis). The visual stimulus was provided by a 3-m diameter sphere with random dots rotating at 30, 45, and 60 degrees per second (degree/s) about the stationary subject's roll, pitch and yaw axes. The subject's head was positioned at the center of the sphere such that it experienced apparent motion in all three axes. Results indicated that in the normal group, symptoms of motion sickness were reported in 21 of 27 test-trials. When labyrinthine-defective subjects were exposed to the roll and pitch stimulus, no sickness symptoms were reported or observed. These results strongly suggest that the vestibular system is necessary for sickness induced by moving visual fields.

Contextual conditioning in variable lexical phonology

Abstract: The variable lexical phonology proposed in Guy (1991) predicts an exponential relationship among rates of retention in word classes of different derivational histories. A class of words that satisfies the structural description of a variable rule at an early lexical level of derivation will undergo multiple operations of the rule and, therefore, exponentially reduced rates of retention, compared to a class of forms that only satisfies the structural description of the rule at the end of the derivation and thus is subject to its operation only once. For the case of English -t,d deletion, it is postulated that monomorphemic words (e.g., mist) are exposed to the deletion rule three times in a derivation, whereas semiweak past tense forms (e.g., left) are exposed twice, and regular past tense forms (e.g., missed) undergo the rule but once.The present article explores the consequences of this model for other variable constraints on a rule, such as the preceding and following segment constraints on -t,d deletion. Word-internal constraints, because they are present throughout the derivation, are shown to have quantitatively different patterns than external constraints, as the latter affect the rule only in its final, post-lexical operation. Four specific quantitative predictions are derived from the model to elucidate this distinction between internal and external constraints, and empirical data are presented to confirm the predictions.

A Ca2+ transport system associated with the plasma membrane of Dictyostelium discoideum is activated by different chemoattractant receptors.

Abstract: Amebae of Dictyostelium exhibit a transient uptake of extracellular Ca2+ approximately 5 s after activation of surface folate or cAMP receptors (Bumann, J., B. Wurster, and D. Malchow. 1984. J. Cell Biol. 98:173-178). To further characterize these Ca2+ entry systems, we analyzed 45Ca2+ uptake by resting and activated amebae. Like the surface chemoreceptors, folate- and cAMP-induced Ca2+ uptake responses were developmentally regulated; the former response was evident in vegetative but not aggregation-competent cells, whereas the latter response displayed the opposite pattern of expression. In contrast, other characteristics of these Ca2(+)-uptake pathways were remarkably similar. Both systems (a) exhibited comparable kinetic properties, (b) displayed a high specificity for Ca2+, and (c) were inhibited effectively by Ruthenium Red, sodium azide, and carbonylcyanide m-chlorophenyl-hydrazone. These results, together with the finding that vegetative cells transformed with a plasmid expressing the surface cAMP receptor exhibit a cAMP-induced Ca2+ uptake, suggest that different chemoreceptors activate a single Ca2+ entry pathway. Additional pharmacological and ion competition studies indicated that receptor-mediated Ca2+ entry probably does not involve a Na+/Ca2+ exchanger or voltage-activated channels. Chemoattractant binding appears to generate intracellular signals that induce activation and adaption of the Ca2(+)-uptake response. Analysis of putative signaling mutants suggests that Ca2+ entry is not regulated by the guanine nucleotide-binding (G) protein subunits G alpha 1 or G alpha 2, or by G protein-mediated changes in intracellular cAMP or guanosine 3,'5'-cyclic monophosphate (cGMP).

Letters, sounds, and symbols: Changes in children's understanding of written language

Abstract: Children between 3–5 years who knew the alphabet but could not read were given three tasks. In the first, they decided which of two words was longer when the word pairs were presented orally, in writing, or accompanying pictures. In the second, they “read” a word when it accompanied a picture of the named object and then again when it was placed with a picture of a different object. Finally, they were given a set of plastic letters with which they could create their own words. Although all the children had explicit knowledge of letters and sounds, they lacked symbolic knowledge of how letters represent sounds. This symbolic knowledge, it is claimed, is a precondition to learning to read.