Showing papers by "McMaster University published in 1981"

Scaling Community Attitudes Toward the Mentally Ill

Abstract: The measurement of public attitudes toward the mentally ill has taken on new significance since the introduction of communitybased mental health care. Previous attitude scales have been constructed and applied primarily in a professional context. This article discusses the development and application of a new set of four scales explicitly designed to measure community attitudes toward the mentally ill. The scales represent dimensions included in previous instruments, specifically, authoritarianism, benevolence, social restrictiveness, and community mental health ideology, but are expressed in terms of an almost completely new set of items that emphasize community contact with the mentally ill and mental health facilities. Data from a study of community attitudes about neighborhood mental health facilities in Toronto are used to test the internal and external validity of the scales. Results of the analysis provide strong support for the validity of the scales and demonstrate their usefulness as explanatory and predictive variables for studying community response to mental health facilities.

Second-harmonic detection with tunable diode lasers — Comparison of experiment and theory

Abstract: A series of experiments are carried out by current modulating a tunable diode laser, and slowly ramping the wavelength to scan weak absorption lines in gases at pressures ranging from 2 to 60 Torr. A lock-in amplifier detects the second harmonic (2f) of the modulation frequency, and the experimental 2f signals are compared with theory. Detailed measurements are made on Lorentzian, Voigt, and Gaussian line profiles, over a wide range of modulation amplitudes. Excellent agreement between experiment and calculation is obtained in all cases. This quantitative understanding enables one to derive true lineshapes and linewidths of very weak absorption lines from measurements of 2f lineshapes only. Results are applicable to trace gas detection using tunable diode lasers, and to other areas of spectroscopy and magnetic resonance where harmonic detection techniques are routinely employed to monitor weak signals.

Quantum Theory of Atoms in Molecules–Dalton Revisited

Abstract: Publisher Summary This chapter deals with the quantum mechanical definition of the average properties of an atom. It is demonstrated that the topological property that defines the atom determines the definition of its average properties. It reviews only the basic topological properties of a charge distribution in this chapter. Their role in the definition of molecular structure and its change has been recently reviewed in detail. A bound atom is an example of an open quantum system. A quantum description of subsystems must be developed, free to exchange charge and momentum with their environment across boundaries that are defined in real space and that in general change with time. The chapter also reviews that the quantum mechanics has been shown to account for the properties of isolated atoms and for the total properties of a molecular system. The increased understanding that would result from the discovery of a firm theoretical basis for Dalton's theory has not been obtained because of a lack of a quantum definition of an atom in a molecule.

Airway responsiveness to histamine and methacholine: relationship to minimum treatment to control symptoms of asthma.

Abstract: We have prospectively examined in 51 patients the relationship between the level of airway responsiveness to histamine and methacholine and the minimum medications required to control asthma. First we determined the least medication that was required to control symptoms so that they did not disturb sleep, were not present on waking, and did not require use of inhaled salbutamol (200 microgram) more than four times daily. When baseline FEV1 was greater than 70% of predicted and when there had been no respiratory infection or allergen exposure for six weeks, histamine and methacholine inhalation tests were carried out on separate days to determine the provocation concentration causing a fall in FEV1 of 20% (PC20). There was a close correlation between the PC20 to the two agents. The patients were grouped into 1, those who required no medication; 2, those who required salbutamol (200 microgram) occasionally but not daily; 3, those who required daily salbutamol; and 4, those who required additional beclomethasone dipropionate. The mean PC20 was highest in group 1 and lowest in group 4; there was a significant difference between each group. The results indicate that airway responsiveness to vasoactive amines is either an important determinant of the severity of asthma and the medication requirements or a consequence of the severity of asthma. They raise the possibility that measurement of responsiveness may be useful in some patients with established asthma to substantiate or question medication needs.

Notes on the Construction of a 'Subjective Vitality Questionnaire' for Ethnolinguistic Groups.

Abstract: Group ‘vitality’ was recently proposed as a framework for objectively categorizing ethnolinguistic groups in terms of their ability to behave as distinctive collective entities in intergroup settings (Giles, Bourhis & Taylor, 1977). ‘Objective’ accounts of group vitality using status, demographic and institutional support data gathered from secondary sources appear a useful tool for comparing ethnolinguistic groups in cross‐cultural research. This article describes a new questionnaire designed to assess how group members subjectively perceive their owngroup position relative to salient outgroups on important ‘vitality’ dimensions. Group members’ ‘subjective’ vitality perceptions may be as important in determining interethnic behaviours as the Group's objectively assessed vitality. The article includes a discussion of how ‘objective’ and ‘subjective’ vitality information can be combined to better account for the dynamics of interethnic relations in multilingual and multicultural settings.

Procedures for change detection using Landsat digital data

Abstract: Resource management agencies are interested in knowing when and how satellite data can be effectively used to monitor environmental change and what information can be expected from remote sensing techniques. In this paper the procedures that might be followed in applying the complementary methods of band ratioing and post-classification change detection to monitor a large remote area are outlined. Examples from research in the Peace-Athabasca Delta are used to illustrate the procedures and expected results.

Branchial and Renal Acid and Ion Fluxes in the Rainbow Trout, Salmo Gairdneri, at Low Environmental pH

Abstract: Rainbow trout were exposed for 4 days to an environmental pH averaging 4.2, an exposure which resulted in a continuous net branchial influx of acid. The influx provoked a progressive depression in blood pH and [HCO3−], virtually complete by 48 h, and a marked increase in renal acid excretion, also complete by 48 h. The increase in the latter was sufficient to remove, at maximum, about half of the protons entering at the gills; those remaining were buffered in body fluids. The low pH exposure also impaired gill ion regulation as indicated by continuous net branchial losses of Na+, Cl− and K+ and by a progressive decline in plasma Na+ and Cl− levels. Evidence is presented which indicates that there was a significant contribution by the intracellular compartment both to the total body ion losses and to the buffering of the body acid load.

Effect of pH on Muscle Glycolysis during Exercise

Abstract: 1. Five males were studied on three occasions, after oral administration of CaCO3 (control), NH4Cl (acidosis) and NaHCO3 (alkalosis), in a dose of 0.3 g/kg, taken over a 3 h period at rest. The subjects then exercised on a cycle ergometer for 20 min at 33% maximal oxygen uptake (VO2 max.), followed by 20 min at 66% and at 95% VO2 max. until exhaustion. 2. Endurance at 95% VO2 max. was longest with alkalosis (5.44 +/- 1.05 min), shortest with acidosis (3.13 +/- 0.97 min) and intermediate in the control study (4.56 +/- 1.31 min); venous blood pH at exhaustion was 7.33 +/- 0.02 (mean +/- 1 SEM), 7.13 +/- 0.02 and 7.26 +/- 0.02 respectively. 3. Concentrations of plasma lactate at exhaustion were 7.10 +/- 0.8 mmol/1 4.0 +/- 0.5 and 7.9 +/- 0.9 mmol/l in the control, acidosis and alkalosis studies respectively. 4. Muscle lactate increased most from rest to exhaustion with alkalosis to 17.1 +/- 2.5 mumol/g and least with acidosis to 12.2 +/- 1.4 mumol/g. Muscle glycogen depletion was comparable in control and alkalosis studies. 5. The lower plasma lactate concentration during exercise in acidosis compared with control and alkalosis appears to be due to an inhibition of muscle glycolysis combined with a reduction in lactate efflux from muscle.

Toughening of Glasses by Metallic Particles

Abstract: The role of elastic, thermoelastic, and interfacial properties in the toughening of a brittle matrix by metallic second-phase particles was studied. Two composites were studied: glass+partly oxidized Ni particles (thermal expansion coefficient of the glasses lower than, equal to, and higher than that of Ni) and glass+partly oxidized Al particles (thermal expansion and elastic moduli equal). Weak interfacial bonding between the nickel and its oxide and developed stress concentrations are the major toughness limitations found in the glass/Ni composites. When the thermal expansion coefficient and elastic modulus of the second phase are sufficiently greater than that of the glass matrix, a propagating crack will bypass the particles. When the thermal and elastic stresses are minimized and satisfactory bonding is achieved (glass/Al composites), a 60x toughness increase was realized.

Characterization of single-mode optical fiber filters.

Abstract: The fabrication of narrowband highly reflecting filters in single-mode step-index fibers was reported recently by Hill et al. [ Appl. Phys. Lett.32, 647 ( 1978)]. The underlying effect on which these filters are based is a photoinduced refractive-index change in the GeO2 used as a core dopant SiO2 fibers. A study is reported aimed at the characterization of such optical fiber filters. A theoretical model is developed, and relevant fiber parameters are determined through intercomparison with experiment. In this way, both the magnitude of the photoinduced index change and its dependence on the writing power coupled into the fiber are determined.

Standardization of inhalation provocation tests: two techniques of aerosol generation and inhalation compared.

Abstract: Comparison of methods of aerosol generation and inhalation is required to improve standardization of inhalation provocation tests. We compared two widely used methods in 10 asthmatics, by measuring the dose and distribution of radiolabeled aerosol deposited in the throat and lung, and the provocation concentration of inhaled histamine required to reduce the FEV1 by 20% (PC20). In one method, aerosol was generated by a DeVilbiss 646 nebulizer attached to a dosimeter, and was inhaled by 5 inspiratory capacity breaths. The measurements with each method were repeated once to determine the reproducibility of results. Both methods deposited the same dose in the lung, but the distribution of the dose was different; the dosimeter method deposited more aerosol in the throat and central airways. The PC20 obtained with each method was the same. The reproducibility of all measurements in the same subject was similar. The lung dose deposited by each method in different subjects varied to the same degree. The results indicated that the bronchial response to inhaled histamine can be measured as reliably using a nebulizer and tidal breathing as by a more complex dose-metering device. They also suggested that, when the methods are regulated as described, the PC20 will have the same clinical significance.

Clinical problem-solving by medical students: a cross-sectional and longitudinal analysis

Abstract: The evolution of clinical reasoning in medical students was studied. A cross-sectional sample consisted of randomly-selected medical students from three classes. Additionally, twenty-two students were observed at yearly intervals from the preclerkship period to the first post-graduate year. Subjects were observed in a clinical examination of a simulated patient, and their thought processes were abstracted from a 'stimulated recall' of the videotaped encounter. The data were transcribed and coded for computer analysis, yielding several variables characterizing the clinical reasoning process, and four measures of outcome of the encounter. Analysis of variance of differences between students at various educational levels and a doctor criterion group indicated that the majority of the process variables were unrelated to educational level. By contrast, diagnostic and management outcomes were positively related to education. The single process variable which was related to both educational level and outcome was an 'hypothesis aggregate score', a measure of the content of the student's diagnostic hypotheses. The results of the study indicate that the problem-solving or clinical reasoning process remains relatively constant from medical school entry to practice. This observation has important implications for clinical teaching and evaluation.

Standardization of inhalation provocation tests: influence of nebulizer output, particle size, and method of inhalation.

Abstract: Standardization of inhalation tests requires a knowledge of factors that will affect the response We measured the output and particle size of six types of nebulizers used for inhalation tests Output varied considerably between nebulizers of different types (012 to 159 ml/min) and to a lesser extent between nebulizers of the same type Particle size varied between 08 and 52 μm aerodynamic mass median diameter (AMMD) The influence of these two properties on bronchial response to inhaled methacholine was examined Nebulizer output but not particle size (between 13 and 36 μm AMMD) altered the response We also examined the effect of change in inspiratory time during inhalation from residual volume to total lung capacity on lung deposition of radiolabeled aerosol and on the provocative concentration of histamine required to reduce the 1-sec forced expiratory volume (FEV 1 ) by 20% (PC 20 ) A reduction in inspiratory time from 8 to 2 sec resulted in a lower total lung dose, relatively more aerosol deposited in central airways, and a higher PC 20 The results emphasize the importance of keeping nebulizer output and pattern of breathing constant when performing inhalation provocation tests if consistent results are to be obtained

Early archaeological sites, hominid remains and traces of fire from Chesowanja, Kenya

Abstract: Recent investigations of Lower Pleistocene sites at Chesowanja have yielded in situ Oldowan and Oldowan-like stone artefacts, evidence of fire and a fragmentary 'robust' australopithecine cranium. Burnt clay found at one artefact locality dated to >1.42±0.07 Myr is the earliest known evidence of fire associated with a hominid occupation site.

The role of conditional drug responses in tolerance to the hypothermic effects of ethanol

Abstract: The role of predrug cues in tolerance to ethanol-induced hypothermia was investigated in two experiments. The results of Experiment 1 demonstrated that tolerance was displayed only when the drug was administered in conjunction with environmental stimuli that had, in the past, accompanied ethanol administration. A conditional hyperthermic response was elicited when a placebo, instead of ethanol, was administered in conjunction with the usual ethanol cues. Results of Experiment 2 suggested that tolerance to ethanol-induced hypothermia can be extinguished by repeated placebo injections. These results indicate that associative processes, previously demonstrated to modulate opiate tolerance, also modulate ethanol tolerance.

A unified potential for mesons and baryons

Abstract: We examine several phenomenological nonrelativistic\(q\bar q\) potentials, with different radial dependences, that fit the low-lying charmonium spectra. With the familar Coulomb-plus-ramp-type dependence the same potential can reproduce the spectra of the light mesons using the Schrodinger equation. With half-strength and the addition of a small three-body term the ground states of the baryons are also obtained.

The Ecology of Weaning

Abstract: At birth and for some time thereafter altricial mammals are, by definition, almost totally dependent on their parents or other caretakers for provision of many of the necessities of life. Although many mammals are born relatively helpless, none continue to depend on conspecifics for sustenance throughout their life cycles. Prior to reaching reproductive age each altricial mammal must become competent to acquire directly from the environment those goods and services which it previously acquired only indirectly as the result of interaction with conspecific caretakers. This transition from an infantile dependence on others for transduction of environmental resources to an adult mode of independent acquisition of necessities is in two senses a gradual process. First, independence with respect to any single need is rarely achieved suddenly; most often a series of graded transitional stages intervene between total dependence on caretakers for supply of a given resource and independent acquisition of that resource. The developing rat pup, for example, moves successively from in utero total dependence for nutrition on mother’s blood, to postparturient total dependence on mother’s milk, to a mixed diet of mother’s milk and solid food, to a diet of solid food transported to the home burrow by adult conspecifics, to feeding trips with adult conspecifics, to independent acquisition of solid food. Second, the juvenile may exhibit adultlike behavior in meeting each of its various needs at different ages. The rat pup, for example, initiates endogenous thermoregulatory behavior some time before it initiates independent feeding on solid foods.

Immunohistochemical evidence for the presence of melatonin in the pineal gland, the retina and the Harderian gland.

Abstract: The presence of melatonin is demonstrated in the pineal gland, the retina and the Harderian gland in some mammalian and non-mammalian vertebrates, using a specific fluorescence labelled antibody technique. Four different potent antibodies against melatonin have been used and compared. In the pineal gland of hamsters, mice, rats and snakes, specific fluorescence, mostly restricted to the cytoplasm of the cells, is detected in pinealocytes. Fluorescence is also detected in the pineal organ of fishes, tortoises and lizards, but it has not been possible, from cryostat sections of fresh tissue, to assert which kind of cell is reacting (photoreceptor cells or interstitial ependymal cells). In the retina, fluorescence is almost exclusively restricted to the outer nuclear layer. In the Harderian gland of mammals and reptiles, fluorescence is localized in the secretory cells of the alveoli and mostly restricted to the cytoplasm surrounding the nucleus. These results are discussed in relation to the concept of melatonin synthesis at extrapineal sites independent of pineal production.

The effect of respiratory muscle fatigue on respiratory sensations.

Abstract: 1. Eight subjects maintained maximal inspiratory pressure as long as possible. The subjects accurately judged the pressure developed, but considered that the sense of effort or motor command increased progressively during the contraction as fatigue developed. 2. A reference inspiratory load was overestimated after maximal inspiratory contractions. 3. These findings are consistent with the hypothesis that awareness of the motor command or effort contributes to the estimation of respiratory loads.

A branched pore kinetic model for activated carbon adsorption

Abstract: A branched pore kinetic model for aqueous phase activated carbon adsorption is presented in which the carbon particle is separated into rapidly and slowly diffusing regions. The model was developed to overcome problems arising from a single rate parameter analysis and is shown to describe experimental data well. In addition to very different rates of transport in the two regions, parameters estimated by regression analysis indicated differences in the adsorptive charac- teristics. As an approximation to the microscopic description of the diffusional process, a model has been developed in this work which divides the carbon particle into two regions of different diffusion rates. The regions are loosely termed macropores and micropores. (These terms should not be confused with their conventional uses to define certain pore size ranges.) Relatively rapid diffusion and adsorption occur in the macropores, and the remaining slow approach to equilibrium occurs in the mi- cropores. The micropores are assumed to be homogeneously distrib- uted throughout the particle and to branch off the larger mac- ropore network which is responsible for radial transport. A schematic diagram of the proposed model is shown in Figure 2. In many respects, the model is similar in form to the dual rate models developed for catalysts of pelletized microporous parti- cles or for molecular sieves (Furusawa and Smith, 1973b; Ruckenstein et al., 1971; Shah and Ruthven, 1977). However, it is not possible to define the dimensions of the microporous sub-units when dealing with activated carbons. Thus, a lumped parameter approach was used to describe diffusion in the micropores. A surface diffusion mechanism was assumed to be responsible for transport in the macropores. Batch kinetic experiments were conducted over extended periods using a closed system, liquid-phase Carberry reactor to obtain accurate data for evaluation of the model parameters. CONCLUSIONS AND SIGNIFICANCE Experimental data collected for the adsorption of phenolics onto activated carbon are accurately described by the pro- posed model. The data show that the observed behavior during a batch kinetic experiment, if followed for a sufficiently long period, is not consistent with a single intraparticle diffusion rate model. Furthermore, by viewing activated carbon adsorp- tion as a dual mechanism rather than as a single mechanism process, equilibrium isotherms and relatively short-term batch kinetic data can be shown to be compatible. From the model parameters which were obtained by regression analysis of the data, several conclusions can be drawn. Measured surface diffusion coeffwients within the macro- pore network are comparable to previously reported

Intrinsic nervous control of migrating myoelectric complexes.

Abstract: The role of intrinsic nerves in the control of migrating myoelectric complexes (MMCs) was studied in seven conscious dogs, each implanted with a set of eight bipolar Trimel wire electrodes. Local areas, 3-5 cm long, were perfused close intra-arterially via an exteriorized heparinized Silastic cannula. Experiments consisted of giving bolus injections of atropine (20-50 micrograms), hexamethonium (20 mg), and tetrodotoxin (TTX; 3-30 micrograms) via the catheter at varying periods of time with respect to the arrival of phase III at the perfused site. Atropine and hexamethonium, given close intra-arterially immediately before the arrival of phase II at the perfused site, blocked its further propagation. Tetrodotoxin given locally also blocked the propagation of phage III, as above. After the block, TTX initiated a new phase III activity at, or distal to, the perfused site in 10 out of 14 perfusions. The new phase III activity propagated distally. This study shows that the mechanisms for the initiation and propagation of MMCs are built into the enteric plexus. Once an MMC is initiated, its propagation is achieved by proximal-to-distal excitation through the intrinsic cholinergic network of neurons. This study explains the lack of any significant changes in the propagation parameters of MMCs after vagotomy or celiac and superior mesenteric ganglionectomy.