Showing papers by "University of British Columbia published in 1983"

New diagnostic criteria for multiple sclerosis: guidelines for research protocols.

Abstract: Several schemes for the diagnosis and clinical classification of multiple sclerosis (MS) have been advanced [l}. The best known is that published by Schumacher et alC31. The criteria for this scheme were established in order to select patients for participation in therapeutic trials, and pertain only to what might be called definite MS. No provision was made for incorporating supportive laboratory data into the diagnostic criteria. As no reliable specific laboratory test for the diagnosis of MS has been discovered, the diagnosis remains a clinical one, and there is still a need for clinical diagnostic criteria. However, several laboratory and clinical procedures have been developed within the last decade which aid greatly in demonstrating neurological dysfunction attributable to lesions, and even the lesions themselves. One problem with the various published diagnostic classifications is their discrepant terminology: what is considered “probable” in one is called “definite” in another. Another problem is that all the proposed schemes require much subjective judgment, a difficulty which cannot be completely overcome but can be diminished by adding to the clinical evaluation the results of laboratory, neuroimaging, neuropsychological, and neurophysiological procedures. Today there is a need for more exact criteria than existed earlier in order to conduct therapeutic trials in multicenter programs, to compare epidemiological surveys, to evaluate new diagnostic procedures, and to estimate the activity of the disease process in MS. Method and Procedure

On the shape of a set of points in the plane

Abstract: A generalization of the convex hull of a finite set of points in the plane is introduced and analyzed. This generalization leads to a family of straight-line graphs, " \alpha -shapes," which seem to capture the intuitive notions of "fine shape" and "crude shape" of point sets. It is shown that a-shapes are subgraphs of the closest point or furthest point Delaunay triangulation. Relying on this result an optimal O(n \log n) algorithm that constructs \alpha -shapes is developed.

Procedure for isolation of bacterial lipopolysaccharides from both smooth and rough Pseudomonas aeruginosa and Salmonella typhimurium strains.

Abstract: Lipopolysaccharide (LPS) is a major component of the outer membrane of gram-negative bacteria. It is now well established that within a single organism, size heterogeneity of this molecule can exist. We have developed a LPS isolation procedure which is effective in extracting both smooth and rough LPS in high yields (51 to 81% of the LPS present in whole cells as quantitated by using hydroxy fatty acid, heptose, and 2-keto-3-deoxyoctonate yields) and with a high degree of purity. The contamination by protein (0.1% by weight of LPS), nucleic acids (1%), lipids (2 to 5%), and other bacterial products was low. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the LPS demonstrated the presence of a high degree of size heterogeneity in the isolated smooth LPS as well as the presence of significant amounts of rough-type LPS. The Pseudomonas aeruginosa LPS interacted well with a monoclonal antibody in a variety of immunochemical analyses. The usefulness of the procedure was demonstrated by comparing LPS preparations obtained from wild-type and mutant strains of P. aeruginosa and Salmonella typhimurium. For example, it was shown that the LPS of an antibiotic supersusceptible mutant Z61 of P. aeruginosa, which was previously characterized as identical to wild type with respect to the ratio of smooth to rough LPS molecules isolated by the phenol-water procedure, actually contained only a small proportion of O-antigenic side chains.

Theories-in-Action: Some Theoretical and Empirical Issues in the Study of Students' Conceptual Frameworks in Science

Abstract: (1983). Theories-in-Action: Some Theoretical and Empirical Issues in the Study of Students' Conceptual Frameworks in Science. Studies in Science Education: Vol. 10, No. 1, pp. 37-60.

Axial-Anomaly-Induced Fermion Fractionization and Effective Gauge-Theory Actions in Odd-Dimensional Space-Times

Abstract: A new quantum field-theoretical technique is developed and used to explore the relationship between even-space-time-dimensional axial anomalies and background-field-induced fermion numbers and Euler-Heisenberg effective actions in odd-dimensional space-times

Sphere-Specific Measures of Perceived Control

Abstract: Evidence for the multidimensionality of perceived control is briefly reviewed. It is proposed that individual differences in perceived control be partitioned into components associated with three primary spheres of behavior: (a) personal efficacy—control over the nonsocial environment as in personal achievement, (b) interpersonal control—control over other people in dyads and groups, and (c) sociopolitical control—control over social and political events and institutions. Assessment instruments are presented for measuring perceived control in each of these three spheres.* A three-factor structural model is tested using confirmatory factor analysis, and the results are strongly supportive. The scales are shown to have impressive convergent and discriminant validity in relation to other individual difference measures. Evidence from several laboratory and field studies is reviewed to support the predictive validity of the three scales. Over the last 10 years, it has become generally accepted that the construct of locus of control is multidimensio nal (for recent reviews, see Phares, 1978; Strickland, 1977). Models of the factor structure, however, have come in several varieties. Many researchers

Pseudomonas aeruginosa isolates from patients with cystic fibrosis: a class of serum-sensitive, nontypable strains deficient in lipopolysaccharide O side chains

Abstract: Twenty-six Pseudomonas aeruginosa strains from patients with cystic fibrosis were typed by the Fisher immunotyping scheme. Only 6 strains were agglutinated by a single typing serum, whereas 15 strains were agglutinated with more than one serum and 5 were not agglutinated by any serum. Neither the polyagglutinable nor the nonagglutinable strains were typable by hemagglutination inhibition or immunodiffusion, suggesting that these polyagglutinable strains did not express multiple serotype antigens, but were instead being agglutinated by antibody to nonserotype determinants. Four typable isolates were resistant to pooled normal human serum, whereas the 12 polyagglutinable and nonagglutinable isolates studied were very sensitive to normal human serum. The outer membranes of 16 strains were isolated and characterized. The data suggested, in general, strong conservation of outer membrane protein patterns. Lipopolysaccharides (LPS) were purified by a new technique which allowed isolation of both rough and smooth LPS in high yields. Three of four typable, serum-resistant strains examined had amounts of smooth, O-antigen-containing LPS equivalent to our laboratory wild type, P. aeruginosa PAO1 strain H103. In contrast, 10 of 12 polyagglutinable or nonagglutinable, serum-sensitive strains had very little or no smooth, O-antigen-containing LPS, and the other two contained less smooth LPS than our wild-type strain H103. In agreement with this data, five independent, rough, LPS O-antigen-deficient mutants of strain H103 were nontypable and serum sensitive. We suggest that the LPS defects described here represent a significant new property of many P. aeruginosa strains associated with cystic fibrosis.

Tests of the automaticity of reading: dilution of Stroop effects by color-irrelevant stimuli.

Abstract: A color word shown next to a color bar can facilitate color naming if it is congruent with the correct response; otherwise it will interfere with color naming. The congruence and conflict effects are both diminished (diluted) by the presentation of a color-neutral word elsewhere in the field. A row of X's also produces some dilution. The dilution effect represents attentional interference rather than sensory interaction or response conflict. Because Stroop effects are susceptible to interference, the involuntary reading of color words does not satisfy one of the standard criteria of automaticity.

Experimental study of transverse bed motion in rotary kilns

Abstract: Slumping and rolling beds have been studied extensively in a continuous pilot kiln and batch rotary cylinders. Solids investigated include nickel oxide pellets, limestone, sand, and gravel. The effect of variables such as rotational speed, bed depth, cylinder diameter, particle size, and particle shape on bed motion has been determined. For a given material, the different modes of bed motion can be delineated conveniently on a Bed Behavior Diagram which is a plot of bed depthvs rotational speed. The scaling of bed behavior with respect to particle size and cylinder diameter requires similarity of Froude number modified by(D/d p)1/2, and pct fill. Measurements of key variables characterizing slumping and rolling beds have also been made.

Pancultural Aspects of the Human Conceptual Organization of Emotions

Abstract: This study investigated whether certain elementary properties of the human conceptual system for categorizing emotions are pancultural or are specific to particular languages and cultures. From similarity judgments provided by native speakers, multidimensional scalings of emotion-related words in Gujarati, Croatian, Japanese, Chinese, and English provided evidence of several pancultural properties. In all five languages, emotion-related words ,fell in roughly a circular order in a space definable by two dimensions: pleasure-displeasure and arousal-sleep. Similar results were obtained from unilingual and bilingual subjects.

Chromosomal mosaicism confined to the placenta in human conceptions

Abstract: Placental and fetal tissues from 46 human pregnancies were cultured and cytogenetically analyzed in an attempt to document the existence of chromosomal mosaicism confined strictly to tissues of extraembryonic origin. In two gestations in which chromosomal mosaicism was found, it was expressed exclusively in placental chorionic cells and was not detected in cells derived from the embryo proper. This demonstration of confined chorionic mosaicism may have implications for the understanding of the fetoplacental unit and for prenatal diagnosis.

Dust-free bedrooms in the treatment of asthmatic children with house dust or house dust mite allergy: a controlled trial.

Abstract: Twenty asthmatic children with prick tests positive for house dust or house dust mites were allocated to two groups that were matched for severity. One group was provided with zippered vinyl covers for pillows, mattresses, and box springs, and instructions for making the bedroom as easy to keep clean as a hospital ward; the other group was not. At the end of a 1-month study period, there was a marked and statistically significant difference in symptoms and signs of asthma between the two groups. Those with a dust-free bedroom had fewer days on which wheezing was observed, medication was given, or an abnormally low peak expiratory flow rate was recorded. Bronchial tolerance to aerosolized histamine significantly improved in the group whose bedrooms had been modified. A dust-free bedroom diminishes bronchial irritability and is a practical and effective method for decreasing asthma in children with house dust or house dust mite allergy.

The cost of visual filtering.

Abstract: Speeded choice responses (reading or naming) to a relevant stimulus under conditions of spatial uncertainty are delayed by the simultaneous occurrence of other events. This "filtering cost" occurs despite high discriminability of target and distractors, which allows parallel detection of the target in search through the same displays. Reading is also delayed when the removal of irrelevant objects from the field coincides with the onset of the target. Filtering costs are caused by the processing of events rather than by the mere presence of irrelevant items. They are eliminated by advance information about the location of the target or by advance presentation of maintained distractors.

Attenuation of heroin reward in rats by disruption of the mesolimbic dopamine system.

Abstract: The rewarding propertics of systemically administered heroin were investigated with a conditioned place-preference paradigm. Reinforcing effects were observed with all doses of heroin tested (0.5, 1.0, 2.0 mg/kg) as indicated by a significant increase in preference for the place paired with drug injections. No similar change in preference was observed following saline injections. The rewarding effect of heroin (2 mg/kg) was attenuated by pretreatment with haloperidol (0.2 mg/kg), but haloperidol alone did not produce a place aversion. Lesions induced by 6-hydroxydopamine (6-OHDA) of the mesolimbic dopaminergic pathway at the level of the nucleus accumbens also attenuated the heroin-induced place preference. In contrast, depletion of central and peripheral noradrenaline induced by 6-OHDA had no significant effect on heroin-induced place preference. These data suggest an important role for the mesolimbic DA system in mediating the reinforcing effects of heroin.

Substance P in the ascending cholinergic reticular system.

Abstract: The neocortex receives a major cholinergic innervation from magnocellular neurones in the basal forebrain1–3. However, an ascending cholinergic reticular system has also been postulated to arise from acetylcholinesterase (AChE)-containing neurones in the midbrain and pontine tegmentum4–5. Lesions of this region decrease both AChE and choline acetyltransferase (ChAT) in various forebrain areas6,7, and recent immunohistochemical studies have identified a group of ChAT-containing cell bodies in the midbrain reticular formation and dorsolateral pontine tegmentum8,9. Here we have combined retrograde tracing with ChAT immunohistochemistry to demonstrate that this tegmental cholinergic cell group also directly innervates the cerebral cortex. Other immunohistochemical studies have indicated that the neuropeptide substance P is also present in certain cells in the laterodorsal tegmentum10, and these too appear to project to the forebrain11,12. We have therefore performed immunohistochemistry for both ChAT and substance P and have discovered that a subpopulation of the ascending cholinergic reticular neurones contains substance P. Thus, peptide–cholinergic coexistence, previously noted in peripheral neurones, also occurs in the brain.

Relationships Between Hydrophobicity and Foaming Characteristics of Food Proteins

Abstract: Hydrophobocity measured fluorometrically for food proteins and pure proteins using cis-parinaric acid as a hydrophobic probe had significant correlations to foaming capacity when the proteins in solution were unfolded by heating in boiling water in the presence of 1.5% dodecyl sulphate prior to fluorometric measurement. Hydrophobicity measured without unfolding, which had previously shown a significant correlation to emulsification, was not significantly correlated with foaming capacity. Two highly significant regression equations were generated: one included hydrophobicity and dispersibility and the other, hydrophobicity and viscosity as the independent variables. High hydrophobicity and viscosity and moderate dispersibility were associated with optimum foaming capacity. There was a significant negative relationship between foam stability and charge density. Hydrophobicity and viscosity were also important in foam stability.

Perceptual objects and the cost of filtering

Abstract: The latency of reading a single word is increased by 20 to 40 msec if another object is present in the display. The delay is affected by the spatial organization of the display: a colored frame causes less delay when it surrounds the word than when it is shown on the opposite side of fixation. A small gap in the frame is also more efficiently detected as a secondary task when the frame is around the word than when the two are spatially separate. The advantage of integrated over separate presentation suggests that a "filtering cost" is incurred when two dis­ tinct perceptual objects compete for attention. Attention in filtering tasks operates on per­ ceptually distinct objects rather than on nodes in a semantic network. The act of reading is usually assumed to be auto­ matic, in the sense that it occurs both without volun­ tary control and without requiring attentional re­ sources, if a word or letter is sufficiently clear and close to the fovea. Yet a consistent delay in naming a single letter is produced by the addition of irrel­ evant objects to the display, even when these ob­ jects are highly discriminable from letters (Eriksen & Hoffman, 1972; Eriksen & Schultz, 1978, p. 18). Distractors such as black disks or color patches add about 30 msec to the latency of letter naming. Eriksen and Schultz labeled this effect cognitive masking. We have found a similar delay in read­ ing a single word when an irrelevant but highly dis­ criminable object is added to the display. We further found that the delay in reading increases as more objects are added, although probably at a decreas­ ing rate; it can be eliminated by precuing the loca­ tion of the word on each trial, and it is reduced or eliminated, with the same displays, when the sub­ ject is asked to press a key whenever a word is shown, instead of to read it (Kahneman, Treisman, & Burkell, in press). The fact that it disappears with precuing links the delay to attention rather than to peripheral in­ terference. The fact that it is reduced in search or detection suggests that the delay arises not in find­ ing the word but in allocating attention to it and/ or in filtering out the irrelevant objects. Focused attention to the word is not required when the re­ sponse is determined directly by the detection of its presence. We suggest attention must be narrowed down to the relevant stimulus, however, when the choice of a response demands further processing. We therefore interpret the observed delay of read

Planning, design, and analysis of tailings dams

Abstract: nPrefaceThe disposal of mine waste, chiefly tailings, has of late assumed an importancenthat transcends even the massive volumes of materials produced annuallynby mining operations. From an engineering standpoint, some tailingsnembankments class among the largest earth structures in the world. Asidenfrom their significance in strictly engineering terms, tailings impoundmentsnreceive intense regulatory attention and public scrutiny. Because of the landnareas they disturb and the varying toxicides of the mine wastes they retain,ntailings impoundments are often the lightning rod for public opposition tonmining projects.Historically, tailings disposal began as the practice of dumping tailingsninto nearby streams and progressed to empirical design of impoundments bynmine operators based on less than satisfactory principles of trial and error.nOnly within about the past 20 years have the principles of geotechnicalnengineering been applied to tailings embankments, ordinarily in the contextnof design practices for water-retention dams. Now, however, planning andndesign of tailings impoundments has become a multidisciplinary enterprise,none that requires a broader background in many diverse fields extendingnbeyond the traditional application of geotechnical knowledge. This book isnintended to provide a bridge between the various technical disciplines involvednin tailings disposal and to illustrate the application of these fields tontailings disposal planning and design. In addition, the intent is to provide thenreader with access to key sources of literature applying to tailings thatnheretofore have been scattered among various conferences, symposia, andnjournals in a wide range of technical fields.The intended audience for the book falls into three main categories:ngeotechnical engineers, mining and metallurgical engineers, and regulatorynpersonnel. Knowledge of soil mechanics fundamentals and basic earth damndesign principles are assumed on the part of the reader and are well coverednin other soil mechanics texts. For the geotechnical engineer, the message isnthat basic earth dam design criteria and concepts alone are not sufficient forntailings embankment design. To the extent that a dam cannot be designednwithout a thorough understanding of the materials it retains, geotechnicalnengineers will find themselves introduced to the metallurgical processes bynwhich tailings are generated, the chemical nature of tailings, and the uniquenengineering behavior of tailings of various types. n

Trade Warfare: Tariffs and Cartels

Abstract: National governments have incentives to intervene in international markets, particularly in encouraging export cartels and in imposing tariffs on imports from imperfectly competitive foreign firms. Although the optimal response to foreign monopoly is usually a tariff, a specific subsidy will be optimal if demand is very convex, as with constant elasticity demand. If ad valorem tariffs or subsidies are considered, a subsidy is optimal if the elasticity of demand increases as consumption increases.The critical conditions in both ad valorern and specific cases hold generally for Cournot ologopoly. Noncooperative international policy equilibrium will be characterized by export cartels and rent-extracting tariffs.

Methyl mercury exposure in northern quebec: ii. neurologic findings in children

Abstract: The relationship between prenatal exposure to methyl mercury and neurologic and developmental abnormalities was ascertained among 234 Cree Indian children aged 12 to 30 months from four northern Quebec communities. A pediatric neurologist, "blinded" to the children's level of exposure, assessed neurologic, physical, mental, and psychosocial development. Methyl mercury exposure was estimated from maternal hair segments representing the period of pregnancy. Abnormality of the tendon reflexes, observed in 13 boys (11 per cent) and in 14 girls (12 per cent), was positively associated with methyl mercury exposure only in boys and there was no consistent dose-response relationship. Other neurologic disorders were less prevalent and none was positively associated with exposure; indeed, incoordination was negatively associated with exposure in girls. The mild, isolated neurologic abnormalities found after prenatal exposure to methyl mercury in northern Quebec were different from the effects of prenatal exposure described in other areas, and their clinical importance can be determined only by continued medical surveillance.