Showing papers by "McMaster University published in 1973"
TL;DR: In this article, a model for the timing of repetitive discrete motor responses is proposed, and a prediction of negative dependency between successive interresponse intervals is confirmed by data from a Morse key tapping task.
Abstract: A model for the timing of repetitive discrete motor responses is proposed, and a prediction of negative dependency between successive interresponse intervals is confirmed by data from a Morse key tapping task A method that makes use of the first-order serial correlation between interresponse intervals is used to distinguish between variance due to a timekeeping process and variance in motor response delays subsequent to the timekeeper These two quantities are examined as a function of mean interresponse interval
931 citations
742 citations
TL;DR: A model is developed to explain the isotope fractionation effects produced in laboratory experiments involving the reduction of sulphate to hydrogen sulphide by the bacterium Desulfovibrio desulfuricans, which differs from previous ones in its use of zero-order kinetics.
464 citations
TL;DR: The thesis that in man, late cutaneous allergic responses can occur in reactions with an isolated involvement of IgE is supported.
Abstract: Relationships between IgE-dependent reactions and late cutaneous allergic responses were examined. Heterologous whole antihuman IgE or its pepsin digest F(ab′)2 product injected intracutaneously produced "immediate" wheal and flare responses followed by late responses. Prausnitz-Kustner reactions were similar in appearance. The late responses were studied morphologically by conventional microscopy and by direct immunofluorescent techniques. The results support the thesis that in man, late cutaneous allergic responses can occur in reactions with an isolated involvement of IgE. There is a discussion of the possible relevance of these observations to antigen-induced allergic reactions in skin and in the respiratory tract.
417 citations
TL;DR: In this article, analogs of models of duration discrimination are related to the timing of discrete motor responses, and the measure of interest is the variability in duration of intervals collected in short interval reproduction tasks.
Abstract: Analogs of models of duration discrimination are here related to the timing of discrete motor responses. The measure of interest is the variability in duration of intervals collected in short interval reproduction tasks. For data from a Morse key-tapping task, it is shown that, taken separately, neither of the models described can completely account for the relation between the mean and the variance of the interresponse intervals.
392 citations
TL;DR: It is shown that as early as 8–12 weeks after birth, focal areas can be identified in the macroscopically normal pig aorta which exhibit an increased endothelial labelling index.
380 citations
TL;DR: This paper showed that the word-superiority effect holds just as strongly for pronounceable nonwords as for words, even when the critical letters are constant over all trials, and therefore concluded that the effect is not due to a memory limitation.
366 citations
TL;DR: In the field of comparative lithology, the concept of facies was introduced by Walther's Law as mentioned in this paper, which states that only those facies and facies areas can be superimposed primarily which can be observed beside each other at present time.
Abstract: The writings of Johannes Walther (1860–1937) have been neglected in the west and his Law of the Correlation (or Succession) of Facies has been ignored or misstated in many textbooks of stratigraphy. Walther should be recognized as a pioneer stratigrapher-sedimentologist, important as both a world traveller and explorer of modern sedimentary environments (deserts, reefs, laterites), and as a theorist. His main theoretical contributions were his championing of the actualistic method for the study of fossils and sedimentary rocks and his founding of the science of comparative lithology. Comparative lithology was seen by Walther as the analogue for sedimentary rocks of comparative anatomy for fossils. It has been neglected in the West until the recent revival of the concept of facies models.
Walther's Law was the key concept within comparative lithology, and was originally stated as follows: “The various deposits of the same facies areas and similarly the sum of the rocks of different facies areas are formed beside each other in space, though in cross-section we see them lying on top of each other. As with biotopes, it is a basic statement of far-reaching significance that only those facies and facies areas can be superimposed primarily which can be observed beside each other at the present time.”
In Russia, Walther's writings appear to have had a greater influence than they have had in Europe and America. They have been partly responsible for the development there of “lithology” as a branch of the geological sciences separate from stratigraphy or petrology.
271 citations
TL;DR: In this article, an experimental investigation of the chemical-initiated (AIBN) bulk polymerization of methyl methacrylate to limiting conversion at temperatures of 50°C, 70°, and 90°C was performed.
Abstract: This manuscript reports on an experimental investigation of the chemical-initiated (AIBN) bulk polymerization of methyl methacrylate to limiting conversion at temperatures of 50°C, 70°, and 90°C. The change in the cumulative differential molecular weight distribution (CDMWD) with respect to conversion was measured by gel permeation chromatography (GPC). These CDMWD's were differentiated to determine the instantaneous differential molecular weight distribution (instantaneous DMWD) over the range of conversions investigated. These experimental instantaneous DMWD's were found to agree with theoretical distributions predicted by classical free-radical kinetics over the entire conversion range and where diffusion control of the termination reactions is dramatic. A correlation of the dimensionless group α (where α = ktdRp/kp2M2) with free volume is proposed. This correlation appears to adequately account for diffusion control of the termination reaction. A kinetic model for the bulk polymerization of methyl methacrylate has been developed. This model should find use in the design, simulation, and optimization of PMMA reactors.
224 citations
TL;DR: In this article, the accuracy of the Lipkin-Nogami version of the BCS method is examined and compared with other methods, for the ground and 0+ excited states of a symmetric two-level model.
207 citations
TL;DR: The authors classify phrases which sound as though they make sense, e.g. "tie the not" as quickly as other phrases which do not even sound right, although they make more err...
Abstract: Subjects can classify, as not making sense, phrases which sound as though they make sense, e.g. “tie the not”, as quickly as other phrases which do not even sound right, although they make more err...
TL;DR: In this paper, a relatively simple hand method is presented for the static and dynamic analyses of uniform structures consisting of interacting shear walls and frames with effectively planar loadings and deformation.
Abstract: A relatively simple hand method is presented for the static and dynamic analyses of uniform structures consisting of interacting shear walls and frames with effectively planar loadings and deformation. The method is applicable also to the static analyses of non-uniform shear wall-frame structures in which step changes of properties occur at several elevations in the height of the structure. Examples are given to show that the method provides results which compare closely with those obtained from more exact but lengthier methods of analysis. Design curves which further simplify the hand computation are also included.
TL;DR: An algorithm is developed to optimize the sequence of locations in order to meet changes in costs, volumes and locations of destinations to extend the static single facility location problem to a model that permits location changes within a planning horizon of r periods.
Abstract: This paper extends the static single facility location problem to a model that permits location changes within a planning horizon of r periods. An algorithm is developed to optimize the sequence of locations in order to meet changes in costs, volumes and locations of destinations.
TL;DR: A phenomenologieal local nucleon-nucleon potential has been constructed satisfying the following criteria: a high-quality fit to two-body bound state and scattering data up to 350 MeV; the amplitudes of all components are weak in the sense that perturbation theory in nuclear matter converges rapidly; the tensor force in the triplet even state is much weaker than in other potential models as discussed by the authors.
TL;DR: It is suggested that mucus, on entering the circulation, can activate coagulations and may explain the frequency of coagulation disorders in patients with mucin-producing adenocarcinoma.
TL;DR: Pigeons' pecks on each of two concurrently available response keys were reinforced under a variable-interval schedule that sometimes allotted food-pellet deliveries to one key and sometimes to the other.
Abstract: Pigeons' pecks on each of two concurrently available response keys were reinforced under a variable-interval schedule that sometimes allotted food-pellet deliveries to one key and sometimes to the other. The keys differed in the number of reinforcements assigned to each and in the number of pellets delivered during each reinforcement. When the total quantity of food associated with each key during a session was constant, the proportion of responses to a key depended on the particular combinations of reinforcer rate and reinforcer magnitude scheduled on each key. A given quantity of food generated more responding on a key when it was delivered frequently in small amounts than when it was delivered infrequently in large amounts.
TL;DR: The authors' observations suggest that the biologically separate plants of C. crispus exhibit distinctive patterns of sulfation of their galactans, and this appears to represent a third carrageenan in the gametophytes.
Abstract: The morphologically similar sporophytic and gametophytic plants of Chondrus crispus Stackhouse were examined and it was shown that the former contain λ-carrageenan. The gametophytes contain ϰ- and two additional carrageenans which are KCl-soluble and may comprise up to 25% of the total carrageenan. After alkaline modification, these KCl-soluble components were separated into a gel and a soluble carrageenan. The gel was indistinguishable from ϰ-carrageenan and presumably was derived from μ-carrageenan while the KCl-soluble fraction possessed a unique infrared spectrum easily distinguished from alkali-modified λ-carrageenan. This appears to represent a third carrageenan in the gametophytes. Our observations suggest that the biologically separate plants of C. crispus exhibit distinctive patterns of sulfation of their galactans. The sporophytes add SO4
2- at C2 of the precursor, whereas the gametophytes appear to add it principally at the available C4 positions. Both types of plant are capable of sulfating at C6 of the 4-linked galactose unit.
TL;DR: In this paper, a comparison is made between recently published theories on the plastic behaviour of dispersion-hardened alloys in which no plastic relaxation occurs, and it is shown that Tanaka and Mori's (1) calculation is a rigorous lower bound for the hardening to be expected.
TL;DR: A method of defining therapist variables in family therapy by stating objectives of training by stating objective of training is proposed and its potential importance for educating a variety of mental health workers and for evaluative research is discussed.
Abstract: A method of defining therapist variables in family therapy by stating objectives of training is proposed. The authors discuss its potential importance for educating a variety of mental health workers and for evaluative research. Learning objectives pertain to three kinds of skills—perceptual, conceptual, and executive—and the levels of necessary skills are outlined for basic (beginning), advanced, and experienced family therapists.
TL;DR: Westermann et al. as mentioned in this paper measured the tensile strength of concave septa in the shells of all Endocer-oidea, Actinoceroidea and Bactritoidea.
Abstract: Westermann, G. E. G.: Strength of concave septa and depth limits of fossil cephalopods.
Simple septa with spherical curvature are present in the shells of all Endocer-oidea, Actinoceroidea, Bactritoidea, and most Nautiloidea and Coleoidea. Such septa act as quasi-hemispherical concave membranes when subjected to hydrostatic pressure. Since the tensile strength of a spherical membrane is directly proportional to the ratio of its thickness and radius of curvature, measurements of these parameters on polished and thin sections of septa can be used to obtain strength of the septum against implosion. Depth limits of fossil cephalopods can be made by calibrating these measurements in terms of recent implosion data on ‘living’Spirula and Nautilus. Estimates of septal strength are augmented by strength estimates for long septal necks and cylindrical to globular connecting rings.
Assuming that actual habitats ranged to approximately two-thirds of the mechanical limits of the shells, the following maximum depth ranges are indicated from this preliminary survey: Endoceroidea 100–450 m; Actinoceroidea 50–150 m; Nautiloidea, Ellesmerocerida 50–200 m, Orthocerida 150–500 m, Oncocer-ida <150, Discosorida <100 m, Tarphycerida <150 m, Nautilida 200–600 m; Bactritoidea c. 400 m; Coleoidea, Aulacocerida 200–900 m, Sepiida 200–1000 m, Belemnitida 50–200 exceptionally 350 m.
TL;DR: In this article, Schottky diode theory is re-evaluated by applying the combined thermionic emission-diffusion theory to both the majority and minority carrier flows across the metal-semiconductor contact.
Abstract: Schottky diode theory is re-evaluated by applying the combined thermionic emission-diffusion theory to both the majority and minority carrier flows across the metal-semiconductor contact. Under both steady-state d.c. and small signal a.c. conditions, numerical solutions to the semiconductor transport equations subject to boundary conditions determined from the combined theory are used to investigate the effects of minority carriers upon the properties of uniformly doped Schottky diodes. High injection effects and contact limitations are shown to influence the minority carrier injection ratio and the total stored minority carrier charge. It is further shown that the small signal impedance of a large class of Schottky diodes becomes inductive under moderate forward bias.
TL;DR: This article showed that the sulfate-sulfide kinetic isotope effect on sulfate reduction is different in seawater sulfide data for modern marine sediments and laboratory experiments, and the difference in isotope effects can be accounted for by Rees' (1973) model of steady-state sulfates reduction: low nutrient supply and undisturbed, stationary bacterial populations in the open system settings tend to generate larger fractionations.
Abstract: Strata-bound sulfide deposits associated with clastic, marine sedimentary rocks, and not associated with volcanic rocks, display distributions of δS34 values gradational between two extreme types: 1. a flat distribution ranging from δS34 of seawater sulfate to values about 25‰ lower; and 2. a narrow distribution around value δS34 (sulfide)=δS34 (seawater sulfate) −50‰, and skewed to heavier values. δS34 (seawater sulfate) is estimated from contemporaneous evaporites. There is a systematic relation between the type of δS34 distribution and the type of depositional environment. Type 1 occurs in shallow marine or brackish-water environments; type 2 occurs characteristically in deep, euxinic basins. These distributions can be accounted for by a model involving bacterial reduction of seawater sulfate in systems which range from fully-closed “batches” of sulfate (type 1) to fully open systems in which fresh sulfate is introduced as reduction proceeds (type 2). The difference in the characteristic distributions requires that the magnitude of the sulfate-sulfide kinetic isotope effect on reduction be different in the two cases. This difference has already been suggested by the conflict between δS34 data for modern marine sediments and laboratory experiments. The difference in isotope effects can be accounted for by Rees' (1973) model of steady-state sulfate reduction: low nutrient supply and undisturbed, stationary bacterial populations in the open system settings tend to generate larger fractionations.
TL;DR: Deaggregation of rabbit platelets aggregated by thrombin was enhanced by the addition of prostaglandin E1 and the same platelets were aggregated several times by addition of the same concentration ofThrombin with washing and resuspension after each aggregation step.
Abstract: Summary. Low concentrations of thrombin (< 0.05 u/ml) cause reversible aggregation of washed rabbit platelets in Tyrode-albumin solution containing apyrase. The same platelets were aggregated several times by addition of the same concentration of thrombin with washing and resuspension after each aggregation step. Deaggregation of rabbit platelets aggregated by thrombin was enhanced by the addition of prostaglandin E1.
In three successive aggregations, rabbit platelets prelabelled with [3H]serotonin released approximately 70% of their radioactivity. Platelet granule nucleotides were labelled by in vivo administration of 32P-labelled orthophosphate: repeated thrombin stimulation caused release of 60–65% of the labelled nucleotides. The release of 3H from [3H]serotonin labelled platelets paralleled the release of 32P-labelled adenine nucleotides and magnesium. The concentration of platelet calcium did not change significantly during repeated thrombin stimulation. Electron microscopy showed nearly complete degranulation of platelets after three thrombin treatments.
The thrice thrombin-treated platelets were more sensitive to ADP-induced aggregation than the control platelets. They did not aggregate upon the addition of low concentrations of thrombin but showed the same extent of aggregation as the control platelets when they were exposed to high concentrations of thrombin.
Rabbit platelets labelled in vitro by incubation with [14C]adenosine showed a decrease in their metabolic nucleotides ([14C]ATP, [14C]ADP)as a result of repeated thrombin treatment. These platelets showed increased glucose uptake and increased lactate production. The thrombin-treated platelets (labelled with [3H]DFP in vitro) survived in the circulation of rabbits for the same time as control platelets.
TL;DR: In this paper, a regression analysis of mean tetrahedral distances with average cation electronegativity was performed and showed a low correlation between corrected bond distances (effective ionic radii) and mean electrophoresis, which suggests that the bond strength of nontetrahedral cations affects to some degree the mean and, therefore, the individual tetralikehedral bond distances in phosphates, arsenates, and vanadates.
TL;DR: In this article, pigeons were trained in an operant, go/no-go, discrimination by successive presentations of discrete, positive and negative trials, and the rate of discriminaion learning based on an auditory cue, on visual cues of different discriminability, and on combined auditory and visual cues was determined.
Journal Article•
TL;DR: It is suggested that the rapid onset of vitamin K deficiency in these patients may have been due to a combination of the use of multiple antibiotics and poor food intake.
Abstract: Twenty-seven patients developed vitamin K deficiency unexpectedly in the postoperative period or during hospitalization for a variety of medical conditions. Twenty-two of the patients were on antibiiotics. Nineteen were on no oral intake during part of their hospital stay, and the remainder had a poor food intake. Fifty percent developed vitamin K deficiency within seven days. It is suggested that the rapid onset of vitamin K deficiency in these patients may have been due to a combination of the use of multiple antibiotics and poor food intake.
TL;DR: In this article, the Sauter mean droplet diameter was found to depend on the product of plate amplitude and frequency and on the system properties, but it was not in general affected by the throughput.
01 Jan 1973
TL;DR: In this article, the light interference pattern produced by illuminating the thin liquid film of water trapped between a rising oil drop and the bulk oil/water interface with white light was observed for various sizes of oil drops for four oil and water systems.
Abstract: The light interference pattern produced by illuminating the thin liquid film of water trapped between a rising oil drop and the bulk oil/water interface with white light was observed for various sizes of oil drops for four oil/water systems. Various concentrations of a surfactant, sodium lauryl sulfate, were used in the water phase. The interference patterns are presented and are broken into mechanisms to explain the different patterns observed. These mechanisms are based on analyses of the shear stress at the bulk (surfactant-bearing) interface and of the interfacial concentration gradient of the surfactant and consequent interfacial tension gradient that this produces in the interface. The mechanisms are rapid approach of the drop to the interface, dimple formation, even drainage, uneven drainage, and film rupture. Uneven drainage is discussed in detail, with particular reference to toluene and anisole drops at the bulk interface. Measurements gave 300–500 A as the film thickness at rupture.