Showing papers by "University of Toronto published in 1986"

Baryons in a relativized quark model with chromodynamics

Abstract: We have studied the three quark system in a relativized version of the quark potential model with chromodynamics. With parameters consistent with those of an analogous study of meson spectroscopy we obtain a successful description of the spectrum of baryons. The model naturally explains the apparent absence of spin‐orbit interactions in baryons.

An Introduction to Sociolinguistics

Abstract: Preface. Acknowledgements. 1. Introduction Knowledge of Language Variation Language and Society Sociolinguistics and the Sociology of Language Methodological Concerns Overview Further Reading Part I: Languages and Communities: 2. Languages, Dialects, and Varieties Language or Dialect? Standardization Regional Dialects Social Dialects Styles, Registers, and Beliefs Further Reading 3. Pidgins and Creoles Lingua Francas Definitions Distribution and Characteristics Origins From Pidgin to Creole and Beyond Further Reading 4. Codes Diglossia Bilingualism and Multilingualism Code-Switching Accommodation Further Reading 5. Speech Communities Definitions Intersecting Communities Networks and Repertoires Further Reading Part II: Inherent Variety: 6. Language Variation Regional Variation The Linguistic Variable Social Variation Data Collection and Analysis Further Reading 7. Some Findings and Issues An Early Study New York City Norwich and Reading A Variety of Studies Belfast Controversies Further Reading 8. Change The Traditional View Some Changes in Progress The Process of Change Further Reading Part III: Words at Work: 9. Words and Culture Whorf Kinship Taxonomies Color Prototypes Taboo and Euphemism Further Reading 10. Ethnographies Varieties of Talk The Ethnography of Speaking Ethnomethodology Further Reading 11. Solidarity and Politeness Tu and Vous Address Terms Politeness Further Reading 12. Talk and Action Speech Acts Cooperation Conversation Further Reading Part IV: Understanding and Intervening: 13. Gender Differences Possible Explanations Further Reading 14. Disadvantage Codes Again African American English Consequences for Education Further Reading 15. Planning Issues A Variety of Situations Further Examples Winners and Losers Further Reading 16. Conclusion References Index

Performance, Slack, and Risk Taking in Organizational Decision Making

Abstract: This research paper investigates the relationship between organizational performance and risk taking in organizational decision making. A complex model is proposed in which the direct relationship, which is triggered by performance below acceptable levels, is negative, but the indirect relationships, which are mediated by organizational slack and decentralization, are positive. A test of the model for a cross-sectional sample of firms shows general support for the model. The findings have implications for theories that view change as arising from stable organizational processes.

Mineralized bone nodules formed in vitro from enzymatically released rat calvaria cell populations.

Abstract: Single-cell suspensions obtained from sequential enzymatic digestions of fetal rat calvaria were grown in long-term culture in the presence of ascorbic acid, Na β-glycerophosphate, and dexamethasone to determine the capacity of these populations to form mineralized bone. In cultures of osteoblastlike cells grown in the presence of ascorbic acid and β-glycerophosphate or ascorbic acid alone, three-dimensional nodules (∼75 μm thick) covered by polygonal cells resembling osteoblasts could be detected 3 days after confluency. The nodules became macroscopic (up to 3 mm in diameter) after a further 3–4 days. Only in the presence of organic phosphate did they mineralize. Nodules did not develop without ascorbic acid in the medium. Dexamethasone caused a significant increase in the number of nodules. Histologically, nodules resembled woven bone and the cells covering the nodules stained strongly for alkaline phosphatase. Immunolabeling with specific antibodies demonstrated intense staining for type I collagen that was mineral-associated, a weaker staining for type III collagen and osteonectin, and undetectable staining for type II collagen. Nodules did not develop from population I and the number of nodules formed by populations II–V bore a linear relationship to the number of cells plated (r=.99). The results indicated that enzymatically released calvaria cells can form mineralized bone nodulesin vitro in the presence of ascorbic acid and organic phosphate.

The permeability of fibrous porous media

Abstract: The literature was searched for experiments and theories related to low-Reynolds-number flow through fibrous porous media, particularly highly porous structures. Experimental data were found for a wide range of materials, from polymer chains to fiberglass, and the results collapse reasonably well when the appropriate dimensionless co-ordinates are employed. Of the theories, accurate solutions of Stokes equation are available for regular arrays of parallel rods, either aligned with or normal to the flow. For irregular arrays and three-dimensional media, approximate permeabilities can be calculated from several flow models.

Mechanisms of regulation of the Na+/H+ exchanger

Abstract: Exchange of Na + for H + was first proposed as a mechanism for renal acidification almost 40 years ago (Pitts, Ayer & Schiess, 1949). However, it was not until 1976 that the existence of such an exchange system was directly demonstrated in vesicles prepared from brush border membranes of kidney tubules (Muter, Hopfer & Kinne, 1976). From studies in renal systems, it has become clear that the exchanger plays an important role in acid secretion and in transepithelial salt and water transport. More recent studies have demonstrated that the Na+/H + exchanger (antiporter) is not unique to epithelial tissues. It appears to be present in most, if not all animal cells, where it has been implicated in a variety of functions, including the regulation of the cytoplasmic pH and Na + concentration, the control of cell volume and the initiation of growth and proliferation. Given the general interest in these phenomena, the rapidly expanding interest in Na+/ H + exchange is not surprising. Many aspects of its properties and functions have been the subject of recent symposia and review articles (Krulwich, 1983; Ires & Warnock, 1984; Aronson, 1985; Mahnensmith & Aronson, 1985). In many unstimulated nonepithelial cell types the antiport appears to be nearly quiescent when the cytoplasmic pH (pHi) is in the physiological range. However, it can be activated by a wide variety of stimuli including hormones, growth factors, tumor promoters and hypertonic shrinking. An emerging pattern of information reveals striking similarities between the modes of activation of several stimuli and suggests that they may share a common mechanism. It is the intent of this brief and speculative review to summarize the evidence concerning

Predicting cardiac complications in patients undergoing non-cardiac surgery

Abstract: The authors prospectively studied 455 consecutive patients referred to the general medical consultation service for cardiac risk assessment prior to non-cardiac surgery, in order to validate a previously derived multifactorial index in their clinical setting. They also tested a version of the index that they had modified to reflect factors they believed to be important. For patients undergoing major surgery, the original index performed less well in the validation data set than in the original derivation set (p<0.05), but still added predictive information to a statistically significant degree (p<0.05). The modified index also added predictive information for patients undergoing both major and minor surgery, demonstrating an area under the Receiver Operating Characteristic curve of 0.75 (95% confidence interval of 0.70 to 0.80). A simple nomogram is presented which will enable conversion of pretest probabilities into posttest probabilities using the likelihood ratios associated with each risk score. It is recommended that clinicians estimate local overall complication rates (pretest probabilities) for the clinically relevant populations in their settings before they apply the predictive properties (likelihood ratios) demonstrated in this study in order to calculate cardiac risks for individual patients (posttest probabilities).

Biosynthetic controls that determine the branching and microheterogeneity of protein-bound oligosaccharides.

Abstract: Detailed studies on the enzyme machinery responsible for the biosynthesis of protein-bound oligosaccharides of the Asn-GlcNAc and Ser(Thr)-GalNAc linkage types have allowed the formulation of some general rules which explain, at least in part, the branching patterns and microheterogeneity of these structures. These rules are discussed under the following headings: competition of two or more enzymes for a common substrate; controls at the level of enzyme substrate specificity (e.g., critical sugar residues which turn enzyme activity on or off, branch specificity, and the role of the polypeptide in the glycoprotein substrate); substrate availability.

The Effect of Verbal and Visual Components of Advertisements on Brand Attitudes and Attitude Toward the Advertisement

Abstract: This article presents the results of a study designed to obtain a better understanding of the effects of using valenced visual information in advertising. In the study, subjects saw advertisements for hypothetical products that contained affect-laden photographs with different valences (Picture Type Manipulation). The results indicate that the affect-laden photographs had an effect on both attitude toward the advertisement ( A ad ) and brand attitudes; however, no differences were found in the product attribute beliefs that were formed. Photographs that were evaluated positively created more favorable attitudes toward the advertisements and brand attitudes, whereas the reverse was true for photographs that were evaluated negatively. The results of an analysis of covariance indicate that the inclusion of both the predicted attitude from structured scales (ΣΣ b i , e i ) and elicited beliefs did not eliminate all the reliable Picture Type effects on brand attitudes; however, the inclusion of A ad did eliminate these effects. In addition, A ad was found to affect brand attitudes for advertisements that contain only copy, and evidence is presented that A ad and brand attitudes are separate hypothetical constructs. Finally, a Dual Component model is presented to explain the effects of visual and verbal information in advertisements.

The challenge of time: Clock-drawing and cognitive function in the elderly

Abstract: This study compares the ‘clock-drawing test’ to two standardized cognitive screens in an elderly population. A newly developed hierarchical classification of errors in clock-drawing correlated well with the severity of scores on both cognitive and screens and also demonstrated acceptable standards for sensitivity and specificity. Clock-drawing appears to be a practical test which can be useful for clinicians as a screen for cognitive impairment in old age and possibly as a marker of change in cognitive status.

Limits on the security of coin flips when half the processors are faulty

Abstract: Protocols which allow an asynchronous network of processors to agree on a r andom (unbiased) bit are proposed in [1] and [4] It is claimed tha t (assuming a t rapdoor funct ion exists), if less than half of the processors are faulty then the correct processors will still agree on a bit whose bias is negligibly small (when the running t ime of the processors is poly(n) the bias is smaller than O(~r) for all k) If half the processors are faulty then these protocols are no longer effective: the bits ou tpu t by the correct processors may be heavily biased We prove tha t the above protocols are opt imal in the sense tha t no protocol exists which tolerates faults in at least half of the processors The result is very general because few restr ict ions are made on the types of communicat ion allowed between correct processors (such as pr ivate channels and global channels) and the correct processors only need to agree on a bit in a weak probabil ist ic sense Also, the faulty processors do not require very much power They can privately communicate wi th each other but they cannot read messages which are exchanged pr ivately between two correct processors An interest ing instance of the problem arises when the number of processors is fixed at two and one of t hem

Explicit Solution of a General Consumption/Investment Problem

Abstract: This paper solves a general consumption and investment decision problem in closed form. An investor seeks to maximize total expected discounted utility of consumption. There are N distinct risky investments, modelled by dependent geometric Brownian motion processes, and one riskless deterministic investment. The analysis allows for a general utility function and general rates of return. The model and analysis take into consideration the inherent nonnegativity of consumption and consider bankruptcy, so this paper generalizes many of the results of Lehoczky, Sethi, and Shreve Lehoczky, J., S. Sethi, S. Shreva. 1983. Optimal consumption and investment policies allowing consumption constraints and bankruptcy. Math. Oper. Res.8 613--636.. The value function is determined explicitly, as are the optimal consumption and investment policies. The analysis is extended to consider more general risky investments. Under certain conditions, the value functions derived for geometric Brownian motion are shown to provide upper and lower bounds on the value functions in the more general context.

Emotion in Psychotherapy

Abstract: The therapeutic process involves many different types of affective phenomena. No single therapeutic perspective has been able to encompass within its own theoretical framework all the ways in which emotion plays a role in therapeutic change. A comprehensive, constructive theory of emotion helps transcend the differences in the therapeutic schools by viewing emotion as a complex synthesis of expressive motor, schematic, and conceptual information that provides organisms with information about their responses to situations that helps them orient adaptively in the environment. In addition to improved theory, increased precision in the assessment of affective functioning in therapy, as well as greater specification of different emotional change processes and means of facilitating these, will allow the role of emotion in change to be studied more effectively. A number of different change processes involving emotion are discussed, as well as principles of emotionally focused intervention that help access emotion and promote emotional restructuring.

Meat flavor volatiles: A review of the composition, techniques of analysis, and sensory evaluation

Abstract: Flavor is an important quality attribute which relates to the organoleptic characteristics of meat. Although perception of flavor is a complex phenomenon, odor is the most important single factor contributing to the overall characteristics of flavor. A large number of compounds have been identified in the volatile fraction of red meats and poultry. An overview of the chemical constituents present in the volatiles of beef, pork, mutton, and chicken is presented according to species and arranged by chemical class--hydrocarbons, alcohols, acids, aldehydes, ketones, sulfides, heterocyclic compounds, etc. The volatile components of cured and uncured pork are compared. The field of meat flavor is assessed in terms of what has been accomplished and the direction in which it may proceed. Techniques for analysis of these volatiles are briefly described.

Convergence of cutaneous, tooth pulp, visceral, neck and muscle afferents onto nociceptive and non-nociceptive neurones in trigeminal subnucleus caudalis (medullary dorsal horn) and its implications for referred pain.

Abstract: Because of the likely involvement of central convergence of afferent inputs in mechanisms underlying referred pain, the activity of single neurones was recorded in the cat's trigeminal (V) subnucleus caudalis (medullary dorsal horn) to test for the presence and extent of convergent inputs to the neurones. In chloralose-anaesthetized or decerebrate unanaesthetized cats, electrical stimuli were applied to afferents supplying facial skin, oral mucosa, canine and premolar tooth pulp, laryngeal mucosa, cervical skin and muscle, and jaw and tongue muscles, and tactile and noxious mechanical and thermal stimuli were applied to skin and mucosa. Considerable proportions of caudalis neurones which could be functionally classified on the basis of their cutaneous receptive field properties as low-threshold mechanoreceptive (LTM), wide-dynamic-range (WDR), or nociceptive-specific (NS) neurones, could be excited by electrical stimulation of several of these afferent inputs. Extensive convergence of afferent inputs, including inputs from skin or mucosal areas outside the neuronal oral-facial receptive field delineated by natural stimuli, was a particular feature of the units classified as cutaneous nociceptive neurones (i.e., WDR and NS). On the basis of antidromic activation, 15% of these WDR and NS neurones were shown to have a direct projection to the contralateral thalamus. The findings question the use of terminology and classifications of somatosensory neurones based only on the cutaneous receptive field properties of the neurones since distinctions between the different neuronal populations become less obvious when properties other than those related to cutaneous afferent inputs are taken into account. Moreover, the observations of extensive convergence of different types of afferents, which was especially apparent in cutaneous nociceptive neurones, also suggest a role for these neurones in mediating deep pain and in spread and referral of pain.

Learning and retention of computer-related vocabulary in memory-impaired patients: method of vanishing cues.

Abstract: Several investigators have suggested that microcomputers might serve as useful external aids for memory-impaired patients. However, knowledge of basic computer vocabulary may be necessary for patients to use and benefit from a microcomputer. The present paper describes a procedure, the method of vanishing cues, which facilitated the acquisition of computer-related vocabulary in four memory-impaired patients. The method involves the systematic reduction of letter fragments of to-be-learned words across trials. Although learning was slow and strongly dependent on first-letter cues, all patients acquired a substantial amount of the vocabulary and eventually were able to produce the target words in the absence of fragment cues. Further, they retained the vocabulary over a 6-week interval and showed some transfer of the knowledge they had acquired. These findings suggest that memory-impaired patients may eventually be able to use a microcomputer as a prosthetic device.

Treatment of the painful neuroma by neuroma resection and muscle implantation.

Abstract: The successful treatment of the painful neuroma remains an elusive surgical goal. This report evaluates one approach to the management of this problem which entails neuroma excision and placement of the proximal end of the nerve away from denervated skin, away from tension, and into a well-vascularized environment: muscle. Seventy-eight neuromas in 60 patients with a mean follow-up of 31 months (range 18 to 43 months) were evaluated. Sixty-seven percent of these patients involved Workmen's Compensation and 57 percent had had at least one previous operation to treat their pain. The results demonstrated good to excellent results in 82 percent of the treated nerves in the entire group. Factors that were predictive of a poorer outcome were (1) digital neuroma (p less than 0.0005), (2) Workmen's Compensation (p less than 0.01), and (3) three or more previous operations for pain (p less than 0.01). Transposition of nerves into small superficial muscles or muscles with significant excursion resulted in treatment failures. The etiology and histopathology of treatment failures are reviewed. Treatment of radial sensory neuromas by transposition of the radial sensory nerve into the brachioradialis muscle when any associated injury to the lateral antebrachial cutaneous nerve was also treated, gave good to excellent relief of pain, and improved hand function in 88 percent of the patients.

Real-Time Euclid: A language for reliable real-time systems

Abstract: Real-Time Euclid, a language designed specifically to address reliability and guaranteed schedulability issues in real-time systems, is introduced. Real-Time Euclid uses exception handlers and import/export lists to provide comprehensive error detection, isolation, and recovery. The philosophy of the language is that every exception detectable by the hardware or the software must have an exception-handler clause associated with it. Moreover, the language definition forces every construct in the language to be time- and space-bounded. Consequently, Real-Time Euclid programs can always be analyzed for guaranteed schedulability of their processes. Thus, it is felt that Real-Time Euclid is well-suited for writing reliable real-time software.

Evaluation of amitriptyline in primary fibrositis. A double‐blind, placebo‐controlled study

Abstract: Seventy patients with primary fibrositis satisfying Smythe's criteria were studied in a 9-week double-blind trial comparing 50 mg amitriptyline with placebo. Fifty-nine patients completed the trial: 27 were treated with amitriptyline, and 32 took a placebo. The patients who received amitriptyline improved significantly in their morning stiffness and pain analog scores at 5 and 9 weeks, compared with baseline scores, whereas no changes were noted in these parameters in the placebo group. Fibrocytic point tenderness did not improve significantly in either of the treatment groups. When compared with the placebo group, the amitriptyline group improved significantly with respect to sleep pattern and patient and physician global assessments. Our data indicate that amitriptyline has some therapeutic benefit in patients with primary fibrositis.