Showing papers by "McMaster University published in 1983"
TL;DR: The empirical relationship between earnings' yield, firm size and returns on the common stock of NYSE firms is examined in this paper, showing that the stock of high E/P firms earn, on average, higher risk-adjusted returns than stock of low E/p firms and that this effect is clearly significant even if experimental control is exercised over differences in firm size.
1,736 citations
TL;DR: The result indicates that the potentiation produced by kindling may be based upon the same mechanism as the LTP effect, and the effect of this potentiation on subsequent tests of short-term and long-term potentiation.
562 citations
TL;DR: In this paper, a survey of commercially available sensors for unmanned machining is presented, including dimensional and proximity sensors, cutting force, spindle force and feed force sensors, and spindle motor (torque and power) sensors.
412 citations
TL;DR: It is concluded that olfactory cues passing from demonstrator to observer provide observers with information con- cerning demonstrators' diets and that these o aroma cues are sufficient to bias diet selection by ob- servers.
401 citations
TL;DR: It is suggested that intracellular acidosis may be the proximate cause of death in trout fitted with dorsal aortic cannulae and that post-exercise mortality is due to excessive ‘lactic acid’ accumulation in the blood.
Abstract: Trout fitted with dorsal aortic cannulae were subjected to 6 min of intensive exercise and monitored over the following 12 h recovery period. Delayed mortality was 40%; the majority of deaths occurred 4–8 h post-exercise. Surviving fish exhibited a short-lived haemoconcentration reflected in increased haematocrit, haemoglobin, plasma protein, Na+ and Ch- levels; an extended rise in plasma [K+]; a quickly corrected respiratory acidosis; and a more prolonged metabolic acidosis in concert with a rise in blood lactate. Dying fish exhibited very similar trends except for a significantly greater metabolic acidosis, lower plasma [Cl-], and the apparent accumulation of an unknown anion in the blood prior to death. Cardiac failure did not occur. Blood metabolic acid levels, while elevated, were only ∼ 50% of peak lactate anion levels and well within the normal range of tolerance, as were all other changes observed in the blood of non-survivors. The hypothesis that post-exercise mortality is due to excessive ‘lactic acid’ accumulation in the blood is discounted. It is suggested that intracellular acidosis may be the proximate cause of death.
391 citations
01 Jan 1983
TL;DR: This chapter describes the conditioning theory of tolerance, summarizes the data which supports the theory, discusses the relevance of the theory to drug dependence, and presents the implications ofthe theory for the treatment of drug abuse.
Abstract: Most theories of drug tolerance and dependence stress the physiological consequences of repeated pharmacological stimulation. There is considerable evidence, however, that the organism’s experience with the drug administration environment, as well as the drug, often importantly contributes to tolerance and dependence. The role of such environmental cues has been elaborated in a model which emphasizes Pavlovian conditioning principles. This account is based on the work of a number of investigators, but primarily Wikler (e.g., 1973, 1977, 1980), who have stressed the contribution of pharmacological learning to drug effects. This chapter describes the conditioning theory of tolerance, summarizes the data which supports the theory, discusses the relevance of the theory to drug dependence, and presents the implications ofthe theory for the treatment of drug abuse. Since some of the material has been summarized previously (Hinson and Siegel, 1980; Siegel, 1978a, 1979 b), this chapter emphasizes developments subsequent to earlier reviews.
391 citations
TL;DR: It is suggested that the occurrence of symptoms is closely linked to the allergic inflammatory reaction and the induction of increased nonallergic responsiveness in subjects with symptoms in the pollen season, dual responses after allergen inhalation tests, and higher levels of ragweed-specific IgE antibodies.
Abstract: Serial measurements of symptoms, peak flow rates, methacholine bronchial responsiveness, and ragweed-specific IgE antibodies were made before and during the ragweed pollen season in 13 sensitized subjects. Allergen inhalation tests were carried out with aerosols of pollen extract out of season in nine subjects; isolated early asthmatic responses were provoked in four, and dual responses (early followed by late) were provoked in five. During the pollen season all subjects developed hay fever and eight had symptoms of asthma. There was a real increase in methacholine responsiveness during the ragweed season. This increase appeared before or after the occurrence of asthma symptoms and changes in flow rates and was greater in subjects with symptoms in the pollen season, dual responses after allergen inhalation tests, and higher levels of ragweed-specific IgE antibodies. The results confirm the occurrence of seasonal asthma and increases in nonallergic (nonspecific) bronchial responsiveness to methacholine from seasonal pollen exposure. They suggest that the occurrence of symptoms is closely linked to the allergic inflammatory reaction and the induction of increased nonallergic responsiveness.
340 citations
TL;DR: Pavlovian conditioning was used to teach rats an association between an arbitrary external cue and food, and presentation of the conditioned cue elicited feeding by sated animals.
Abstract: Pavlovian conditioning was used to teach rats an association between an arbitrary external cue and food. Presentation of the conditioned cue elicited feeding by sated animals. The meal constituted approximately 20 percent of daily intake, and it was compensated for by a reduction of subsequent intake.
330 citations
TL;DR: Potentiation was significantly larger when muscles were tested in a shortened position regardless of the position at which the preceding MVCs had been performed, and after longer voluntary contractions, the potentiation was partially suppressed by fatigue.
324 citations
TL;DR: Results indicated that kindling increased, rather than reduced, inhibition in the dentate gyrus, suggesting an enhanced resistance to inhibitory failure.
296 citations
TL;DR: The authors make explicit the conceptual bases of the original biological approaches to learning, identifies reasons why they failed to change fundamentally the study of instrumental and classical conditioning, and proposes an alternative approach to the use of ecological and evolutionary principles in studies of conditioning.
Abstract: The adequacy of traditional approaches to the study of animal learning to account fully for learning phenomena has been seriously questioned during the past decade. Critics of traditional analyses advocated a biological orientation to the interpretation of associative processes and introduced a variety of concepts intended to provide a new framework for the study of animal learning. This promise of a reorientation of the field has not been realized. The concepts of biological constraints, adaptive specializations, and situation specificity of learning have had a less profound influence on the general process approach to instrumental and classical conditioning than anticipated. The present paper makes explicit the conceptual bases of the original biological approaches to learning, identifies reasons why they failed to change fundamentally the study of instrumental and classical conditioning, and proposes an alternative approach to the use of ecological and evolutionary principles in studies of conditioning. We suggest a renewed comparative approach to the study of learning phenomena that avoids many of the difficulties inherent in earlier formulations by providing (1) a strategy for the discovery of adaptive specializations in learning, (2) an ecological framework for the discussion of these adaptive specializations, and (3) a renewed emphasis on the study of species differences in learning.
TL;DR: The present approach is the first which simultaneously gives estimates of the pre-clinical state duration, the sensitivity of the screening method, and the underlying incidence rate in the screened group, while also taking into account the problem of length-biased sampling.
Abstract: In this paper, the authors show how data on the observed prevalence of disease at a screen and on the incidence of disease during intervals between screens may be used to estimate jointly the distribution of the length of time during which individuals remain in the pre-clinical state and the sensitivity of the screen. Apart from being of biologic interest, such estimates may be used to evaluate the length of time by which the date of diagnosis could be advanced by screening (the lead time) as well as to predict the relative effectiveness of various alternative screening strategies. The methodology uses only information which should be routinely available in the course of a typical screening program, and makes only rather mild statistical assumptions. The authors illustrate the methods with breast cancer screening data from the Health Insurance Plan of Greater New York (HIP). Although these data have been analyzed by several other authors, the present approach is the first which simultaneously gives estimates of the pre-clinical state duration, the sensitivity of the screening method, and the underlying incidence rate in the screened group, while also taking into account the problem of length-biased sampling.
TL;DR: In this paper, a projection matrix is constructed which can be used to decompose the linear problem into the solution of two subproblems, by first removing each balance around process units with an unmeasured component flow rate.
Abstract: Flow rate measurements in a steady-state process are reconciled by weighted least squares so that the conservation laws are obeyed. A projection matrix is constructed which can be used to decompose the linear problem into the solution of two subproblems, by first removing each balance around process units with an unmeasured component flow rate. The remaining measured flow rates are reconciled, and the unmeasured flow rates can then be obtained from the solution of the conservation equations. The basic case contains constraints which are linear in the component and the total flow rates. The method is extended to cases with bilinear constraints, involving unknown parameters such as split fractions.
Chi-square and normal statistics are used to test for overall gross measurement errors, for gross error in each node imbalance which is fully measured, and for each measurement adjustment.
TL;DR: Bermuda is a stable, mid-oceanic carbonate platform for which a particularly complete record of Late Pleistocene eustatic sea-level fluctuation has been reconstructed from a detailed study of geological field relationships combined with an extensive programme of U-series and amino-acid racemization geochronology as discussed by the authors.
TL;DR: Receptor binding estimates of the number of GABA and associated benzodiazepine receptors were made in several brain regions following kindling, suggesting a possible mechanism for the kindling-induced enhancement of inhibition observed in previous evoked potential experiments.
TL;DR: The authors showed that judgments of the strength of the relation between binary input and output variables are not based on the appropriate statistical measure, the difference between two conditional probabilities, and that the overall pattern of judgments in the three experiments is mainly explicable on the basis of two principles: (1) judgments tend to be based on a difference between confirming and disconfirming cases and (2) causal compatibility in the representation of the inputs and outputs plays a critical role.
TL;DR: In this paper, a preliminary model for the interaction of low pH and calcium is proposed and evidence for adaptation to acid stress and for the origin of acid lethality is discussed. But the results contrast sharply with the effects on trout of acid exposure in hard water (Ca2+≥ 1600μequiv/l), where net ion losses and mortality are reduced and H+ uptake increased.
Abstract: Exposure of adult rainbow trout to low pH (pH 4.3) in soft water (Ca2+ = 223 μequiv/1) caused a substantial ionic disturbance which arose primarily because of large net losses at the gills. In contrast, renal ion losses were low initially and declined even further because of a pronounced reduction in urine flow. A net influx of H+ occurred across the gills but this was not sufficient to cause a blood acid-base disturbance or a renal response. Although branchial ion and H+ fluxes declined with time, blood ion levels did not return to normal and many of the fish died. Further reduction in water calcium (Ca2+ = 69 μequiv/l) provoked a higher mortality and a more substantial ionic imbalance. These results contrast sharply with the effects on trout of acid exposure in hard water (Ca2+≥ 1600μequiv/l), where net ion losses and mortality are reduced and H+ uptake increased. A preliminary model for the interaction of low pH and calcium is proposed and evidence for adaptation to acid stress and for the origin of acid lethality is discussed.
TL;DR: In this paper, a commercial copper-zinc oxide catalyst promoted with K2 CO3 was compared with published work and the optimum promoter concentration was about 0.5% by weight.
Abstract: Alkali oxides added to methanol catalysts increase the formation of ethanol, n-propanol and isobutyl alcohol. This result has been known for many years, yet few quantitative studies have been reported in the literature. Data obtained on a commercial copper-zinc oxide catalyst promoted with K2 CO3 are presented and compared with published work. The optimum promoter concentration was about 0.5% by weight. The H2 to CO feed ratio was important in determining the higher alcohol selectivity. The rate of production of isobutyl alcohol varied as pp while for methanol, ethanol and n-propanol both exponents were positive and less than 1.6. Decreasing the hydrogen to carbon monoxide ratio from 2 to 0.5 more than doubled the isobutyl alcohol selectivity. Chain growth schemes predicting the higher alcohol selectivity are presented and estimates of the parameters are given.
L'addition d'oxydes alcalins aux catalyseurs de la production du methanol augmente la formation d'ethanol, de n-propanol et d'alcool isobutylique; ce resultat est connu depuis nombre d'annees, mais jusqu'ici peu d'etudes quantitatives sur ce point ont paru dans la litterature. On rapporte les resultats d'une etude faite sur un catalyseur commercial forme de cuivre et d'oxyde de zinc et active par K2 CO3; on compare aussi les resultats obtenus avec ceux de la litterature. La concentration optimale de l'activateur est 0.5% en poids. Le rapport d'alimentation H2/CO est important pour la selectivite en alcools superieurs. La vitesse de production de l'alcool isobutylique varie comme pp, tandis que, dans le cas du methanol, de l'ethanol et du propanol normal, les deux exposants etaient positifs et inferieurs a 1.6. En diminuant le rapport H2/CO de 2 a 0.5, on a double la selectivite en alcool isobutylique. On presente des modeles de croissance de chaǐnes pour prevoir la selectivite en alcools superieurs et on donne des estimations des differents parametres.
TL;DR: The data suggest that low levels of TCDD may interact with cytoplasmic receptors for T CDD in the thymus and induce biologically significant immunosuppression through activation of suppressor cells.
TL;DR: In this article, three color enhancements, an overlay of band 5, ratios of bands 5 and 7, and a vegetation index, were generated using 1974 and 1978 Landsat data of Hamilton, Ontario.
TL;DR: Adult rainbow trout, acclimated to external calcium concentrations ranging from 60–5700 μequiv/1, were exposed to pH 4.0-4.1 for 44 h, and ion losses declined substantially, largely due to a rapid decline in passive efflux but also to a slower, partial recovery in sodium transport.
Abstract: Adult rainbow trout, acclimated to external calcium concentrations ranging from 60–5700 μequiv/1, were exposed to pH 4.0-4.1 for 44 h. Initially, this exposure provoked massive net losses of sodium and chloride across the gills which arose through a combination of an inhibition of active transport and, more importantly, a stimulation in diffusional efflux. Subsequently, ion losses declined substantially, largely due to a rapid decline in passive efflux but also to a slower, partial recovery in sodium transport. External calcium concentration was virtually without effect on ion fluxes either prior to or following acid exposure but had a definite effect during acid exposure. This effect was initially upon the ratio of C1 − to Na + loss and later upon the degree of inhibition of sodium and chloride transport. Possible mechanisms to explain the complex interactions of calcium and pH are proposed.
TL;DR: Stable carbon isotope analysis of archaeological human bone collagen is becoming increasingly useful in diet reconstructions, and as discussed by the authors describes the techniques that have been found useful in carrying out such analyses, and discusses the requirements for measurement accuracy and inter-laboratory calibration.
TL;DR: In this paper, a time domain simulation approach to the analysis of chatter is applied to improve the knowledge of the effect of cutting speed "lobing" and of special cutters (nonuniform pitch) on stability of milling.
TL;DR: In this paper, the hot-isostatic pressing of lead, tin and PMMA has been studied, using a rig which enables continuous measurement of density during a test, and the dominant mechanisms of densification are plasticity and creep.
TL;DR: In this article, the Mg content of calcite varies directly with temperature and in a sufficiently pronounced manner that a 1°C rise in depositional temperature of a speleothem containing 500 ppm Mg, at ∼10°C, would be seen as an increase of ∼35ppm Mg.