Showing papers by "University of British Columbia published in 1987"
TL;DR: Criteria for the evaluation of case research are established and several characteristics useful for categorizing the studies are identified and examples of research areas that are particularly well-suited to investigation using the case research approach are concluded.
Abstract: This article defines and discusses one of these qualitative methods - the case research strategy Suggestions are provided for researchers who wish to undertake research employing this approach Criteria for the evaluation of case research are established and several characteristics useful for categorizing the studies are identified A sample of papers drawn from information systems journals is reviewed The paper concludes with examples of research areas that are particularly well-suited to investigation using the case research approach
5,310 citations
TL;DR: This paper proposes a logic for default reasoning, develops a complete proof theory and shows how to interface it with a top down resolution theorem prover, and provides criteria under which the revision of derived beliefs must be effected.
4,146 citations
TL;DR: In this paper, the authors propose a statisticalique du rapport de vraisemblance construite a partir de la distribution conditionnelle des observations, and donne les estimateurs du maximum de VRAISEMblance for les parametres de nuisance.
Abstract: On propose une statistique du rapport de vraisemblance construite a partir de la distribution conditionnelle des observations, etant donne les estimateurs du maximum de vraisemblance pour les parametres de nuisance
1,261 citations
01 Oct 1987
TL;DR: This paper shows that closed world evaluation of an arbitrary query may be reduced to open world evaluated of so-called atomic queries, and shows that the closed world assumption can lead to inconsistencies, but for Horn data bases no such inconsistencies can arise.
Abstract: Deductive question-answering system generally evaluate queries under one of two possible assumptions which we in this paper refer to as the open and closed world assumptions. The open world assumption corresponds to the usual first order approach to query evaluation: Given a data base DB and a query Q, the only answers to Q are those which obtain from proofs of Q given DB as hypotheses. Under the closed world assumption, certain answers are admitted as a result of failure to find a proof. More specifically, if no proof of a positive ground literal exists, then the negation of that literal is assumed true. In this paper, we show that closed world evaluation of an arbitrary query may be reduced to open world evaluation of so-called atomic queries. We then show that the closed world assumption can lead to inconsistencies, but for Horn data bases no such inconsistencies can arise. Presented at the Workshop on Logic and Data Bases, Toulouse, France, November 16-18, 1977.
1,106 citations
TL;DR: A variant of the cauliflower mosaic virus 35S promoter with transcriptional activity approximately tenfold higher than that of the natural promoter was constructed by tandem duplication of 250 base pairs of upstream sequences, which should be very useful for obtaining high levels of expression of foreign genes in transgenic plants.
Abstract: A variant of the cauliflower mosaic virus 35S promoter with transcriptional activity approximately tenfold higher than that of the natural promoter was constructed by tandem duplication of 250 base pairs of upstream sequences. The duplicated region also acted as a strong enhancer of heterologous promoters, increasing the activity of an adjacent and divergently transcribed transferred DNA gene several hundredfold, and to a lesser extent, that of another transferred DNA gene from a remote downstream position. This optimized enhancer element should be very useful for obtaining high levels of expression of foreign genes in transgenic plants.
976 citations
TL;DR: The findings of facial action variation across sleep/waking state were interpreted as indicating that the biological and behavioral context of pain events affects behavioral expression, even at the earliest time developmentally, before the opportunity for learned response patterns occurs.
Abstract: Pain expression in neonates instigated by heel-lance for blood sampling purposes was systematically described using measures of facial expression and cry and compared across sleep/waking states and sex. From gate-control theory it was hypothesized that pain behavior would vary with the ongoing functional state of the infant, rather than solely reflecting tissue insult. Awake-alert but inactive infants responded with the most facial activity, consistent with current views that infants in this state are most receptive to environmental stimulation. Infants in quiet sleep showed the least facial reaction and the longest latency to cry. Fundamental frequency of cry was not related to sleep/waking state. This suggested that findings from the cry literature on qualities of pain cry as a reflection of nervous system 'stress', in unwell newborns, do not generalize directly to healthy infants as a function of state. Sex differences were apparent in speed of response, with boys showing shorter time to cry and to display facial action following heel-lance. The findings of facial action variation across sleep/waking state were interpreted as indicating that the biological and behavioral context of pain events affects behavioral expression, even at the earliest time developmentally, before the opportunity for learned response patterns occurs. Issues raised by the study include the importance of using measurement techniques which are independent of preconceived categories of affective response.
969 citations
TL;DR: Using bone scan- positive stress fractures for diagnosis indicates that tarsal stress fractures are much more common than previously realized and time to diagnosis and recovery is site-dependent.
Abstract: We analyzed cases of 320 athletes with bone scan-positive stress fractures (M = 145, F = 175) seen over 3.5 years and assessed the results of conservative management. The most common bone injured was the tibia (49.1%), followed by the tarsals (25.3%), metatarsals (8.8%), femur (7.2%), fibula (6.6%), pelvis (1.6%), sesamoids (0.9%), and spine (0.6%). Stress fractures were bilateral in 16.6% of cases. A significant age difference among the sites was found, with femoral and tarsal stress fractures occurring in the oldest, and fibular and tibial stress fractures in the youngest. Running was the most common sport at the time of injury but there was no significant difference in weekly running mileage and affected sites. A history of trauma was significantly more common in the tarsal bones. The average time to diagnosis was 13.4 weeks (range, 1 to 78) and the average time to recovery was 12.8 weeks (range, 2 to 96). Tarsal stress fractures took the longest time to diagnose and recover. Varus alignment was found frequently, but there was no significant difference among the fracture sites, and varus alignment did not affect time to diagnosis or recovery. Radiographs were taken in 43.4% of cases at the time of presentation but were abnormal in only 9.8%. A group of bone scan-positive stress fractures of the tibia, fibula, and metatarsals (N = 206) was compared to a group of clinically diagnosed stress fractures of the same bone groups (N = 180), and no significant differences were found. Patterns of stress fractures in athletes are different from those found in military recruits. Using bone scan for diagnosis indicates that tarsal stress fractures are much more common than previously realized. Time to diagnosis and recovery is site-dependent. Technetium99 bone scan is the single most useful diagnostic aid. Conservative treatment of stress fractures in athletes is satisfactory in the majority of cases.
869 citations
TL;DR: HLA-DR-positive reactive microglia were found in gray matter throughout the cortex of postmortem brains of patients with senile dementia of the Alzheimer type (SDAT) and were particularly concentrated in the areas of senile plaque formation.
813 citations
TL;DR: The possibility that the Y-encoded finger protein is the testis-determining factor is discussed, and models of sex determination accommodating the finding of a related locus on the X chromosome are proposed.
811 citations
TL;DR: The present results indicate that a CGRP-like peptide is present in a wide range of primary sensory neurons probably not related to specific sensory modalities and often this peptide coexists with other biologically active peptides.
Abstract: By use of the indirect immunofluorescence technique the distribution of calcitonin gene-related peptide (CGRP)-like immunoreactivity (LI) has been analyzed in cervical and lumbar dorsal root ganglia of untreated and colchicine-treated rats. In addition, lumbar ganglia were examined 2 weeks after transection of the sciatic nerve. The occurrence of CGRP-positive cells in relation to ganglion cells containing substance P-, somatostatin-, galanin-, cholecystokinin (CCK)-, and vasoactive intestinal polypeptide (VIP)/peptide histidine isoleucin (PHI)-LI has been evaluated on consecutive sections as well as using elution-restaining and double-staining techniques.
687 citations
TL;DR: In this paper, a two-component model of socially desirable responding (SDR) as self-deception and impression management is presented, where one or both components may be related conceptually to the variable of interest such that indiscriminate control of SDR removes the predictive power of a measure.
Abstract: Socially desirable responding (SDR) refers to presenting oneself favorably regarding current social norms and standards. While SDR has concerned organizational researchers as a contaminant in self-assessment, it is argued here that such a presumption is inappropriate and that SDR may represent content variance in some settings. Further, a two-component model of SDR as self-deception and impression management is presented. One or both components of SDR may be related conceptually to the variable of interest such that indiscriminate control of SDR removes the predictive power of a measure. Implications of this reconception are considered for measuring and controlling SDR in organizational research. The distinction between self-deception and impression management is used to clarify a number of theoretical issues.
TL;DR: This paper found that the profitability of multinational growth over the whole period was independent of its destination, supporting the view that the primary source of the superior performance of multinationals was competitive advantage rather than the higher rate of profit in the industries of other countries.
Abstract: Over the period 1972–84, profitability among 304 large, British manufacturing companies was positively related to their degree of multinationality. Moreover, increases in overseas production were strongly associated with increases in sales and profitability. The profitability of multinational growth over the whole period was independent of its destination, supporting the view that the primary source of the superior performance of multinationals was competitive advantage rather than the higher rate of profit in the industries of other countries.
TL;DR: The difference in phenomenology accompanying insight and noninsight problem solving is proposed to be used to define insight, and the data indicated that noninsights problems were open to accurate predictions of performance, whereas insight problems were opaque to such predictions.
Abstract: People’s metacognitions, both before and during problem solving, may be of importance in motivating and guiding problem-solving behavior. These metacognitions could also be diagnostic for distinguishing among different classes of problems, each perhaps controlled by different cognitive processes. In the present experiments, intuitions on classic insight problems were compared with those on noninsight and algebra problems. The findings were as follows: (1) subjective feeling of knowing predicted performance on algebra problems but not on insight problems; (2) subjects’ expectations of performance greatly exceeded their actual performance, especially on insight problems; (3) normative predictions provided a better estimate of individual performance than did subjects’ own predictions, especially on the insight problems; and, most importantly, (4) the patterns-of-warmth ratings, which reflect subjects’ feelings of approaching solution, differed for insight and noninsight problems. Algebra problems and noninsight problems showed a more incremental pattern over the course of solving than did insight problems. In general, then, the data indicated that noninsight problems were open to accurate predictions of performance, whereas insight problems were opaque to such predictions. Also, the phenomenology of insight-problem solution was characterized by a sudden, unforeseen flash of illumination. We propose that the difference in phenomenology accompanying insight and noninsight problem solving, as empirically demonstrated here, be used to define insight.
TL;DR: A general algorithm for the computation of chemical equilibria in complex systems containing non-ideal solutions has been developed in this paper, which is a G-minimization based on repeated linear and nonlinear programming steps.
TL;DR: Biogeoclimatic ecosystem classification is a system of ecological classification widely used in British Columbia as discussed by the authors, which is based on a synthesis of vegetation, climate, and soil data.
TL;DR: Methods of grading radiologic progression of osteoarthritis (OA) will be useful to the investigator in designing experimental studies and to the clinician in determining the rate of disease progression in an individual patient.
Abstract: We evaluated methods of grading radiologic progression of osteoarthritis (OA). Sets of radiographs were assessed separately by 8 readers who were blinded to the time sequence. Included were radiographs of patients with OA of the hands (24 pairs), hips (40 pairs), and knees (32 pairs). Most films were taken 12-60 months apart. The relative contribution of individual joints (such as particular interphalangeal joints), of observations (such as narrowing or spurs), and of a single joint compartment (such as the medial or lateral compartment of the knee) toward evidence of OA progression was evaluated, as well as the reliability and concordance of scoring, and the sensitivity in detecting change. In assessing OA of the hand, the greatest sensitivity was achieved by reading a single posteroanterior bilateral hand radiograph for narrowing, spurs, and erosions, and scoring 10 joints (second and third distal interphalangeal, second and third proximal interphalangeal, and trapeziometacarpal joints, bilaterally), using a scale of 0-3. In OA of the hip, a single anteroposterior radiograph assessed for joint space narrowing and cyst formation yielded the greatest sensitivity. In OA of the knee, an anteroposterior radiograph, with weight-bearing, assessed for narrowing, spurs, and sclerosis in both the medial and lateral compartments yielded the greatest sensitivity. These techniques will be useful to the investigator in designing experimental studies and to the clinician in determining the rate of disease progression in an individual patient.
TL;DR: The authors compared the empirical fits of three non-normal candidates and the normal distribution for daily changes in the logarithms of exchange rates, using maximum likelihood estimation of the parameters and chi-square goodness-of-fit tests.
TL;DR: A generalization of string matching, in which the pattern is a sequence of pattern elements, each compatible with a set of symbols, is investigated, which shows that generalized string matching requires a time-space product of $\Omega ({{n^2 } / {\log n}})$ on a powerful model of computation, when the alphabet is restricted to n symbols.
Abstract: Given a pattern string of length n and an object string of length m, the string matching problem asks for the positions of all occurrences of the pattern in the object string. This paper investigates a generalization of string matching, in which the pattern is a sequence of pattern elements, each compatible with a set of symbols. The alphabet of symbols is infinite, with its members encoded in a finite alphabet. In contrast to standard string matching, which can be solved in simultaneous linear time and constant space, it is shown that generalized string matching requires a time-space product of $\Omega ({{n^2 } / {\log n}})$ on a powerful model of computation, when the alphabet is restricted to n symbols. Our proof uses a method of Borodin. The obvious algorithm for generalized string matching requires time $O(NM)$, where N is the length of the encoding of the pattern, and M is that of the object string. We describe an algorithm which solves generalized string matching in time $O(N + M + mN^{{1 / 2}} {\o...
TL;DR: The lifetime of negative muons has been measured in 50 elements plus 8 isotopes, and the total capture rates have been deduced and compared to various calculations.
Abstract: The lifetime of negative muons has been measured in 50 elements plus 8 isotopes. For light elements the accuracy of 2 to 3 ns is a significant improvement over most previous measurements. In heavier elements the accuracy is 1 to 2 ns, which is comparable to, or better than, previous results, with reasonable agreement in most cases. For $^{18}\mathrm{O}$, Sc, Dy, and Er there were no previous data. The total capture rates have been deduced and compared to various calculations.
TL;DR: A number of factors affecting anthocyanin stability and color are discussed in this article, including the presence of an ox-onium ion adjacent to carbon 2, which makes the pigments particularly susceptible to nucleophilic attack by such compounds as sulfur dioxide, ascorbic acid, hydrogen peroxide and even water.
Abstract: A number of factors affecting anthocyanin stability and color are discussed in this review. The anthocyanins are probably the most spectacular of plant pigments since they are responsible for most of the red, purple and blue pigmentation of flowers, fruits and vegetables. However, because of their highly reactive nature, anthocyanins readily degrade, or react with other constituents in the media, to form colorless or brown colored compounds. The presence of an ox-onium ion adjacent to carbon 2 makes the anthocyanins particularly susceptible to nucleophilic attack by such compounds as sulfur dioxide, ascorbic acid, hydrogen peroxide and even water. Loss of anthocyanin pigmentation also occurs in the presence of oxygen and various enzymes, and as a result of high temperature processing. A certain degree of pigment stabilization may be conferred by acylation with various organic acids, copigmentation, self-association and/or metal chelation. In addition, pH has a marked effect on anthocyanin stability, and on the color of media containing these pigments. A number of anthocyanin-rich sources have been investigated for their potential as commercial pigment extracts. Although their application is primarily limited to acidic media, continued research on the chemistry of anthocyanins may lead to application and stabilization of these pigments in a wider variety of food products.
TL;DR: Further elucidation of factors that cause cells to marginate in the pulmonary circulation and a more complete understanding of the factors that control their adherence to endothelium, migration into the interstitial and airspace, and phagocytic function will undoubtedly lead to a better understanding of both the physiology and pathology of the lung.
Abstract: The fact that the lung stores a large proportion of the marginated pool of neutrophils is a result of the anatomy of the pulmonary microcirculation. This capillary bed is made up of a network of a very large number of segments, many of which have smaller diameters than the neutrophils. Both neutrophils and erythrocytes must deform to pass through the capillary bed, but as the neutrophils are larger and less deformable, they pass through the segments more slowly. The slower movement of neutrophils through the pulmonary capillaries produces little obstruction to erythrocyte flow because the very large number of segments allows the erythrocytes to stream around those that are filled with neutrophils. The size of the marginated pool of neutrophils in the lung depends on the balance between forces that propel the neutrophils through the capillary segments and those that tend to retard them. Activation of the PMN both decreases their deformability and increases their adherence to endothelium, which results in increased numbers of neutrophils in the lung and a reduction in the number circulating in the blood. There is growing evidence that the adherence of the neutrophil to the endothelial cell is mediated by the CD omega 18 on the surface of the neutrophil. The absence of these proteins leads to lack of neutrophil adherence and migration, whereas factors that enhance adherence lead to increased expression of these glycoproteins. The fact that activated neutrophils can also damage normal tissue has led to several attractive hypotheses concerning the pathogenesis of lung diseases such as emphysema and the ARDS. Further elucidation of factors that cause cells to marginate in the pulmonary circulation and a more complete understanding of the factors that control their adherence to endothelium, migration into the interstitial and airspace, and phagocytic function will undoubtedly lead to a better understanding of both the physiology and pathology of the lung.
TL;DR: Observations support the hypothesis that low proteoglycan concentrations in all the discs of a spine precede degeneration.
TL;DR: Air pollution data from 17 sampling stations between Windsor and Peterborough in Southern Ontario, for January, February, July, and August in 1974 and 1976 to 1983, have been analyzed and it is shown that there are high correlations between different pollutants and between these and temperature in the summer.
TL;DR: The findings indicate that the same formulation can be applied to contrast discrimination and that changes in the estimated values of internal noise, rather than changes in sampling efficiency, play the major role in determining properties of contrast discrimination.
Abstract: Even the highest contrast sensitivities that humans can achieve for the detection of targets on uniform fields fall far short of ideal values. Recent theoretical formulations have attributed departures from ideal performance to two factors—the existence of internal noise within the observer and suboptimal stimulus information sampling by the observer. It has been postulated that the contributions of these two factors can be evaluated separately by measuring contrast-detection thresholds as a function of the level of externally added visual noise. We wished to determine whether a similar analysis could be applied to contrast discrimination and whether variation of the increment threshold with pedestal contrast is due to changes in internal noise or sampling efficiency. We measured contrast-increment thresholds as a function of noise spectral density for near-threshold and suprathreshold pedestal contrasts. The experiments were conducted separately for static and dynamic noise. Our findings indicate that the same formulation can be applied to contrast discrimination and that changes in the estimated values of internal noise, rather than changes in sampling efficiency, play the major role in determining properties of contrast discrimination. Implications for models of contrast coding in vision are discussed.
TL;DR: Results indicated that perception was significantly less categorical among the severely disabled readers in ihrcc of the lour speech perception tasks, and the possible implications of this small, but significant, difference arc discussed.
Abstract: ll has been hypothesized thai children with specific disabilities in reading may have subtle auditory and/or speech perception deficits. To address this question, recent investigations have focussed on whether reading disabled children show categorical speech perception. These efforts have yielded equivocal results. The present study was designed to attempt to help resolve this controversy by comparing the performance of severely disabled readers with normal readers in four speech perception tasks. Results indicated that perception was significantly less categorical among the severely disabled readers in ihrcc of the lour speech perception tasks. The possible implications of this small, but significant, difference arc discussed. KESUME II a ete suggcre que des cnlants ayant des diflicultcs a lire pouvaicnt avoir des deficits subtils d'audition ct/ou de perception du langagc. Les eludes qui se sont aftaquccs a ce problcmc ont produit des rcsultats pour le moins equivoques. L'ctudc presentee ici a tenUS dc rcsoudre cette controverse en comparant la performance d'enfants en difficultc dc lecture avee des enfants normaux dans quatre taches dc perception du langagc. Les resultats ont montrc que la perception etait significativement moins categoriquc the/, les enfants handicapes dans trois des quatre taches. Les implications de cettc difference, petite mais significative, sont discuses. The relation between speech perception and the process of reading has been outlined previously (Godfrey, Syrdal-Lasky, Millay, & Knox, 1981). Basically, in reading, the printed word has to be mapped on to the underlying phonologic representation (Liberman, 1983; Read, 1971). This process includes converting individual graphemes to phonemes and strings of graphemes to the overlapping and highly encoded (Liberman, Cooper, Shankweiler, & Studdert-Kennedy, 1967) larger linguistic units such as syllables and words. In order to make this conversion, the reader must have a stable, context-independent phonological representation available on which to map the linguistic units. Research in speech perception has shown that adults, children, and even prelinguistic infants tend to perceive speech sounds in a categorical fashion. That is, when presented with several varying naturally produced speech syllables or *We wish to thank the students, staff, and board members of the Kenneth Gordon School in New Westminster, B C and the students, staff, and school board ol'licc of the Vancouver Public Schools for their participation and cooperation in this project. Special thanks are extended to Margaret Follis, principal of the Kenneth Gordon School. Our appreciation is also extended to Dr. Alvin M. Liberman, Director, Haskins Laboratory, for making us welcome at Haskins, to Dr. Ignatious Mattingly for help synthesizing the stimuli, and to Dr. Patrice Dunn for serving as a consultant to the grant. Special thanks to Kathy Searcy for all the hours she spent collecting the data and to Margaret Arab for performing the data analyses. This research was supported by a grant from the British Columbia I lealth Care Research Foundation ( # 103(81 2)) to the authors. Address reprint requests to Janet V. Werker, Department of Psychology, The University of British Columbia, Vancouver, BC, Canada V6T IY7
TL;DR: Walker et al. as mentioned in this paper examined the relation between reasoning about hypothetical and real-life dilemmas, the validity of Gilligan's notion of sex-related moral orientations (response vs. rights), and the relation of moral orientation to moral stage.
Abstract: WALKER, LAWRENCE J.; DE VRIES, BRIAN; and TREVETHAN, SHELLEY D. Moral Stages and Moral Orientations in Real-Life and Hypothetical Dilemmas. CHILD DEVELOPMENT, 1987, 58, 842-858. We examined 2 influential theories of moral reasoning: Kohlberg's moral stage model and Gilligan's moral orientation model. 3 issues were of particular interest: (a) the relation between reasoning about hypothetical and real-life dilemmas, (b) the validity of Gilligan's notion of sex-related moral orientations (response vs. rights), and (c) the relation of moral orientation to moral stage. Participants were 80 family triads (mother, father, and child, total N = 240), with children drawn from grades 1, 4, 7, and 10. In individual interviews, they discussed hypothetical dilemmas and a personally generated real-life dilemma, which were scored for both moral stage and moral orientation. Content analyses were also conducted for the real-life dilemmas. Results indicated consistency in moral stage between responses to hypothetical and real-life dilemmas, supporting the notion that stages are holistic structures. However, few individuals showed consistent use of a single moral orientation. The evidence regarding the relation between sex and orientation was inconsistent. Among other results, sex differences were evident in dilemma content but were not evident in orientations when dilemma content was controlled. The sexes did not differ in stage of moral development; however, there were moral stage differences as a function of moral orientation.
TL;DR: In this review, the experimental literature on opioids and sexual behavior in humans and laboratory animals is examined and new research directions involving the study of endogenous opioid systems, opioid receptor subtypes, and the opioid modulation of neurotransmitter systems are outlined.
TL;DR: The diacetyl monoxime method was suitable for urea determinations in all the seawater samples examined; it was easily automated, and the results were accurate and reproducible, and this modified technique is recommended for measuring disolved concentrations of urea in seawater.
Abstract: A comparison between the diacetyl monoxime and urease methods for measuring dissolved concentrations of urea in seawater was conducted in artificial seawater, phytoplankton-culture filtrate and both natural and ureaspiked field samples from coastal and oceanic enviroments during 1984. The urease technique underestimated urea concentrations in unbuffered photoplankton-culture filtrate as a result of the inhibition of the urease enzyme, causing the incomplete hydrolysis of urea in these samples. Factors responsible for inhibiting urease included pH, seawater ions, and possibly extracellular metabolites produced in unialgal cultures. Seawater type and time of sample collection were important variables affecting urea measurement by the urease method, and recovery of internal standards ranged from 40 to 100%. Increasing the heating time of the urease assay, or the concentration of urease added to the seawater samples increased the amount of urea determined by the urease method. However, measured values were still less than the concentration of the urea internal standards. The diacetyl monoxime method was suitable for urea determinations in all the seawater samples we examined; it was easily automated, and the results were accurate and reproducible. This modified technique is recommended for measuring disolved concentrations of urea in seawater.
TL;DR: The general thin-wall formalism first elaborated by Israel is developed and applied to the investigation of the motion of various bubbles arising in the course of phase transitions in the very early Universe including new phase bubbles, old phase remnants, and domains.
Abstract: This is a systematic study of the evolution of thin shell bubbles in general relativity. We develop the general thin-wall formalism first elaborated by Israel and apply it to the investigation of the motion of various bubbles arising in the course of phase transitions in the very early Universe including new phase bubbles, old phase remnants, and domains. We consider metric junction conditions and derive constraints both on the decay of metastable states and on the evolution of non- equilibrium scalar field configurations (fluctuations) following from the global geometry of spacetime.