Showing papers by "McMaster University published in 1976"
TL;DR: In this paper, the authors examined various aspects of black-hole evaporation and proposed a technique for replacing the collapse by boundary conditions on the past horizon, which retains the essential features of the collapse while eliminating some of the difficulties.
Abstract: This paper examines various aspects of black-hole evaporation. A two-dimensional model is investigated where it is shown that using fermion-boson cancellation on the stress-energy tensor reduces the energy outflow to zero, while other noncovariant techniques give the Hawking result. A technique for replacing the collapse by boundary conditions on the past horizon is developed which retains the essential features of the collapse while eliminating some of the difficulties. This set of boundary conditions is also suggested as the most natural set for a preexistent black hole. The behavior of particle detectors under acceleration is investigated where it is shown that an accelerated detector even in flat spacetime will detect particles in the vacuum. The similarity of this case with the behavior of a detector near the black hole is brought out, and it is shown that a geodesic detector near the horizon will not see the Hawking flux of particles. Finally, the work of Berger, Chitre, Nutku, and Moncrief on scalar geons is corrected, and the spherically symmetric coupled scalar-gravitation Hamiltonian is presented in the hope that someone can apply it to the problem of black-hole evaporation.
4,344 citations
TL;DR: The results suggest a sexual dimorphism in the neural organization underlying cognition during a major period of childhood in boys and girls between 6 and 13 years of age.
Abstract: Specialization of the right hemisphere for spatial processing was studied in 200 normal boys and girls between 6 and 13 years of age. Boys performed in a manner consistent with right hemisphere specialization as early as the age of 6. Girls showed evidence of bilateral representation until the age of 13. The results suggest a sexual dimorphism in the neural organization underlying cognition during a major period of childhood. The results, which have implications for reading instruction, are discussed in terms of a possible sex difference in neural plasticity during development and the clinical consequences of such a difference.
541 citations
TL;DR: In this paper, three measurement techniques are applied to several samples of the general public to measure the social preferences for ten different health states: the standard gamble technique by von Neumann-Morgenstern, a time trade-off technique by the author, and a category scaling method are analyzed with respect to their feasibility, reliability, validity and comparability.
Abstract: Health state preferences measured on the general public provide useful information in their own right as well as being necessary data for the application of many health status index models. But, how should the preferences be measured? This paper reports the results of an empirical investigation in which three measurement techniques are applied to several samples of the general public to measure the social preferences for ten different health states. The standard gamble technique by von Neumann-Morgenstern, a time trade-off technique by the author, and a category scaling method are analyzed with respect to their feasibility, reliability, validity and comparability.
540 citations
TL;DR: A new technique for analysis of environmental tritium is described in this paper, which consists of mass-spectrometer measurements of 3He allowed to accumulate for suitable times in degassed samples of water sealed in containers made of Corning type-1720 glass.
533 citations
TL;DR: The results indicate than an association between environmental cues and the systemic effects of morphine is crucial to tolerance development.
Abstract: Rats were made tolerant to morphine in either of two environments and then assessed for morphine-induced alteration of pain sensitivity in both environments. Analgesic tolerance was displayed when rats were tested in that environment in which they previously received morphine, but not in the alternative environment. The results indicate than an association between environmental cues and the systemic effects of morphine is crucial to tolerance development.
313 citations
TL;DR: In this article, the energy-momentum tensor of a massless scalar field in a general two-dimensional spacetime and evaluate it in a twodimensional model of gravitational collapse was calculated.
Abstract: We calculate the vacuum expectation value, ${T}_{\ensuremath{\mu}\ensuremath{
u}}$, of the energy-momentum tensor of a massless scalar field in a general two-dimensional spacetime and evaluate it in a two-dimensional model of gravitational collapse. In two dimensions, quantum radiation production is incompatible with a conserved and traceless ${T}_{\ensuremath{\mu}\ensuremath{
u}}$. We there-fore resolve an ambiguity in our expression for ${T}_{\ensuremath{\mu}\ensuremath{
u}}$, regularized by a geodesic point-separation procedure, by demanding conservation but allowing a trace. In the collapse model, the results support that picture of black-hole evaporation in which pairs of particles are created outside the horizon (and not entirely in the collapsing matter), one of which carries negative energy into the future horizon of the black hole, while the other contributes to the thermal flux at infinity.
309 citations
TL;DR: The response to a standard dose of heparin was studied in 20 patients with venous thromboembolism and large inter-individual variations were found in the anticoagulant effect.
Abstract: The response to a standard dose of heparin was studied in 20 patients with venous thromboembolism. The heparin regimen consisted of intravenous injection of 70 units per kg, followed after 90 minutes by a maintenance dose of 400 units per kg per 24 hours given by continuous infusion. Plasma heparin activity and the activated partial thromboplastin time (APTT) were measured at intervals to determine clearance of the initial injection and the response to maintenance dose. Large inter-individual variations were found in the anticoagulant effect and these were due in part to differences in heparin clearance and in part to differences in the APTT response to given amounts of heparin (heparin effect index). The heparin half-life was 63 +/- 15 minutes when plasma heparin activities were used for this calculation and 84 +/- 71.5 minutes when the APTT was used. These results are similar to values previously reported in normal volunteers. Four of the 20 patients had pulmonary embolism and in these heparin half-life was significantly shortened (P less than 0.005).
268 citations
TL;DR: In this paper, the results of an experimental investigation are presented in which dichloromethane (methylene chloride) boiling on a glass surface was studied using laser interferometry and high-speed photography.
Abstract: The results of an experimental investigation are presented in which dichloromethane (methylene chloride) boiling on a glass surface was studied using laser interferometry and high-speed photography. New data for active site density, frequency of bubble emission, and bubble departure radius were obtained in conjunction with measurements of the volume of microlayer evaporated from the film underlying the base of each bubble for various combinations of heat flux and subcooling. These results were used to support a model for predicting boiling heat flux incorporating microlayer evaporation, natural convection, and nucleate boiling mechanisms. Microlayer evaporation heat transfer is shown to represent a significant proportion of the total heat transfer for the range of heat flux and subcooling investigated.
254 citations
TL;DR: Impedance plethysmography using the cuff technique has been compared with venography in 346 consecutive patients with suspected venous thromboembolism and is an accurate method for detecting proximal vein thrombosis but has limitations which include the possibility of false positive results due to arterial insufficiency and muscle tension.
Abstract: Impedance plethysmography using the cuff technique has been compared with venography in 346 consecutive patients with suspected venous thromboembolism. The limbs were classified according to the venographic results as no thrombosis, proximal (popliteal, femoral, or iliac) vein thrombosis, and calf thrombosis. A discriminant analysis was performed. The impedance plethysmographic result was normal in 386 of 397 limbs which were normal on venography, a specificity of 97%, and abnormal in 124 of 133 limbs which showed proximal vein thrombosis, a sensitivity of 93%. Seventy-three of 88 limbs with calf vein thrombi and a normal impedance plethysmographic result. The sensitivity in 29 limbs with asymptomatic proximal vein thrombosis was 83%. Impedance plethysmography is an accurate method for detecting proximal vein thrombosis but has limitations which include the possibility of false positive results due to arterial insufficiency and muscle tension.
251 citations
TL;DR: In this article, new trace element analyses have been made on the composite Canadian Precambrian shield samples reported in 1967 and the overall mean abundance of Cr has been revised to 35 ppm (from 99).
208 citations
TL;DR: Three new peptides have been isolated from the venom of the common European honey bee: one is a fragment of the known peptide melittin, and some properties of the peptides are described.
Abstract: A procedure is described for the simultaneous separation of all the peptides (other than those present in trace amounts) contained in the venom of the common European honey bee (Apis mellifera). Three new peptides have been isolated: one is a fragment of the known peptide melittin. Some properties of the peptides are described.
Journal Article•
TL;DR: The concept of turbidity current was introduced to the geological profession in 1950 by Arnold Bouma as discussed by the authors and has been used extensively in the field of sedimentary geology and geomorphology.
Abstract: lntroduetlon To the sedimentologist. Me turbidity current concept is both simple and elegant. Each turb~dite (defined as the deposit of aturbidity current) is the result of a single, short lived event, and once deposited, it is extremely unlikely to be rewciked by other currents. The concept is elegant because it allows the interpretation of thousands of graded sandstone beds, alternating with shales. as the result of a series of similar events. and it can safely be stated that nosimilar volume of clastic rock can be interpreted so simply. In this review. I will begin by studying the "classical" turbidite, and will then gradually broaden the scale to encompass turbidites and related coarse clastic rocks in their typical depositional environments deep sea fans and abyssal plains. The concept of turbidites was introduced to the geological profession in 1950. At that time, nobody had observed a modern turbidity current in the ocean, yet the evidence for density currents had become overwhelming. The concept accounted for graded sandstone beds that lacked evidence of shallow water reworking, and it accounted for transported shallow water forams in the sandstones, yet bathyal or abyssal benthonic forams in interbedded shales. Low density currents were known in lakes and reservoirs, and they appeared to be competent to transport sediment for fairly long distances. Many of these different lines of evidence were pulled together by Kuenen and Migliorini in 1950 when they publishedtheir experimental results in a now classic paper on "Turbidity currents as a cause of graded bedding". A full review of why and how the concept was established in geology has recently been published (Walker. 1973). After its introduction in 1950, the turbidity current interpretation was applied to rocks of many different ages. in many different places. Emphasis was laid upon describing a vast and new assemblage of sedimentary structures. and using those structures to interpret paleocurrent directions. In the absence of a turbidite lacies model (see pevious article in this issue of Geoscience Canada), there was no norm with which lo compare individual examples, no framework for organizing observations. no logical basis for prediction in new situations, and no basis for a consistent hydrodynamic interpretation. Yet gradually duringthe years 1950-1 960, a relatively small but consistent set of sedimentary features began to be associated with turbidites. These are considered in the following list, and can now be taken as a set of descriptors for classical turbidites: 1 ) Sandstone beds had abrupt, sharp bases, and tended to grade upward into finer sand. silt and mud. Some of the mud was introduced into the basin by the turbidity current (it conta~ned shallow benthonic forams), but the uppermost very fine mud contained bathyal or abyssal benthonic forams and represented the constant slow rain of mud onto the ocean floor. 2) On the undersurface (sole) of the sandstones there were abundant markings, now classified into three types: tool marks, carved into the underlying mud by rigid tools (sticks. stones) in the turbidity current; scour marks, cut into the underlying mud by fluid scour: and organic markings trails and burrows filled in by the turbidity current and thus peserved on the sole. The tool and scour markings give an accurate indication of local flow directions of theturbidity currents, and by now, many thousands have been measured and used to reconstruct paleoflow patterns in hundreds of turbidiie basins. 3) Within the graded sandstone beds. many different sedimentary structures were recorded. By thelate 1950s, some authors were proposing turbidite models, or ideal turbidiies. based upon a generalization of these sedimentary structures and the sequence in which they occurred. This generalization is akin tothe distillation process discussed in the previous paper, and the final distillation and publication of the presently accepted model was done by Arnold Bouma in 1962. A version of the Bouma model is shown in Figure 1
TL;DR: The social transmission of acquired behavior may be seen as providing an alternative to the genetic transmission of behavioral propensities, allowing a population to maintain the established patterns and to incorporate behavioral novelty into its repertoire rapidly.
Abstract: Publisher Summary There are essentially three non-independent means by which the behavior characteristic of a population may remain constant from one generation to the next. First, adaptive behavior in population members may be largely endogenously organized and genetically transmitted as propensities influencing ontogeny. Second, similar patterns of behavior in successive generations of a population may result from similar histories of individual transaction with the physical environment. And, third, long-term homogeneity of behavior may result from the transmission of patterns of behavior from individual to individual within a population as a consequence of social interaction. In most species, the adaptive behavior acquired independently by an individual as a result of its transactions with the physical environment is not readily transmitted either to others of its generation or to members of future generations. Although the genetic material influencing the behavior of an individual that allowed it to acquire some pattern of behavior may be preserved and disseminated within a population via the mechanisms of Mendelian recombination and neo-Darwinian natural selection, the specific responses acquired by any individual are lost in every generation with the death of their acquirer. The social transmission of acquired behavior may be seen as providing an alternative to the genetic transmission of behavioral propensities, allowing a population to maintain the established patterns and to incorporate behavioral novelty into its repertoire rapidly. The chapter describes the examples of patterns of behavior apparently transmitted among conspecifies, as well as a variety of field and laboratory findings are reviewed, which have been or can be interpreted as demonstrating the social transmission of acquired behavior, and defines the range of phenomena to be considered.
TL;DR: The results suggest two mechanisms for regulating the metabolic NO(3) (-) pool: (a) a transfer from the storage pool which requires light; and (b) aTransfer from the external medium which requires either glucose or light.
Abstract: Barley seedlings grown in the dark with 10 mm KNO 3 have low levels of nitrate reductase activity even though large amounts of No 3 − accumulate in the leaves. When the leaves are excised and transferred to the light, there is an increase in nitrate reductase activity both in the presence and absence of exogenous NO 3 − . When the leaves are transferred to a glucose solution (0.05 m) but kept in the dark, induction of nitrate reductase activity occurs only when fresh NO 3 − is added to the system. In dark-grown leaves, there are small traces of NO 3 − in a “metabolic pool.” Addition of glucose does not alter this distribution. Light, on the other hand, results in an appreciable accumulation of NO 3 − in the metabolic pool. There is a linear correlation between nitrate reductase activity and the size of the metabolic NO 3 − pool. Our results thus suggest that NO 3 − accumulates in a storage pool when seedlings are grown in continuous darkness. The transfer of this NO 3 − to an active metabolic pool is mediated by light but not by glucose. We believe that this transfer of NO 3 − leads to the induction of nitrate reductase. When NO 3 − is included in the medium, both light and glucose increase its incorporation into the metabolic pool. The results suggest two mechanisms for regulating the metabolic NO 3 − pool: ( a ) a transfer from the storage pool which requires light; and ( b ) a transfer from the external medium which requires either glucose or light.
TL;DR: In this paper, the inclusions are assumed to have preserved their D/H ratios since the time of deposition and they are interpreted as samples of seepage water from which enclosing calcite was deposited.
TL;DR: Prophylaxis resulted in a slight increase in bleeding-minor wound hematoma, mean volume of blood transfused, and a post-operative hematocrit fall in treated patients, however, increased bleeding was clinically minor, and prophylactic was well tolerated.
Abstract: The effect of low-dose heparin prophylaxis on venous thrombosis and bleeding after major elective surgery was studied in a prospective controlled study of 820 patients. The total incidence of venous thrombosis detected with leg-scanning using fibrinogen labeled with radioactive iodine (125I) was reduced from 16.0% in the control group to 4.2% in treated patients. More important, the incidence of popliteal or femoral vein thrombosis was reduced from 2.9% to 1.0%. Prophylaxis resulted in a slight increase in bleeding—minor wound hematoma, mean volume of blood transfused, and a postoperative hematocrit fall in treated patients. However, increased bleeding was clinically minor, and prophylaxis was well tolerated. (JAMA235:1980-1982, 1976)
TL;DR: In this article, over 250 samples of Atlantic seawater have been analyzed for the dissolved helium isotopes, and distinctive pattern has emerged Two components of excess 3 He are seen: a component due to in situ decay of nuclear-era tritium, and a primordial component evolved from the solid Earth.
TL;DR: Sodium archidonate-induced shape change and aggregation of platelets may be caused by the release of ADP by products of sodium arachidonate metabolism and (ii) directly by the products of Sodium arachidenate metabolism, independently of released ADP.
Abstract: Sodium arachidonate causes shape change and aggregation of rabbit or human platelets that have been washed and then degranulated by treatment with thrombin. Since these platelets do not contain releasable adenosine diphosphate (ADP) and the aggregation is not inhibited by the creatine phosphate-creatine phosphokinase system, sodium arachidonate must be able to cause aggregation that is independent of the release of ADP. Since aggregation of these platelets induced by sodium arachidonate is inhibited by acetylsalicylic acid or indomethacin, it seems likely that products (such as prostaglandin G2) formed from sodium arachidonate are responsible for aggregation. Thus, sodium arachidonate-induced shape change and aggregation of platelets may be caused (i) by the release of ADP by products of sodium arachidonate metabolism and (ii) directly by the products of sodium arachidonate metabolism, independently of released ADP.
TL;DR: It is hoped that the paper will help to unify the health status index concept, will serve to standardize terminology and notation, and will facilitate comparisons of the various models.
Abstract: A general mathematical formulation of the health status index model is developed. Equations are given for three types of population health indexes and for the determination of the amount of health improvement created by a health care program. Fourteen of the major health status index models from the literature are analyzed, and it is shown that each can be viewed as a special case of the general formulation. It is hoped that the paper will help to unify the health status index concept, will serve to standardize terminology and notation, and will facilitate comparisons of the various models.
01 Sep 1976-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the standard free energies of formation of the oxides, sulfides and oxysulfides of cerium and lanthanum under steelmaking conditions have been calculated and used to predict the behavior of rare earths in steelmaking.
Abstract: The standard free energies of formation of the oxides, sulfides and oxysulfides of cerium and lanthanum under steelmaking conditions have been calculated and used to predict the behavior of rare earths in steelmaking. Deoxidation and desulfurization constants, expressed in terms of Henrian activities, have been used to construct a precipitation diagram which indicates the sequence of rare earth inclusion formation. An enrichment of lanthanum in (RE)-oxysulfide and cerium in (RE)-sulfide is predicted. It is also predicted that rare earths should be able to reduce the soluble oxygen and sulfur contents of liquid steel well below the contents presently found in most industrial and laboratory practices. A simple method of calculating steelmaking additions for complete rare earth control of inclusion composition is presented.
TL;DR: A crustacean thought to be extremely rare, Axius serratus, was discovered in large numbers in polluted regions of the Strait of Canso, which affects the geotechnical properties of sediments on the sea floor.
Abstract: Axius serratus, a crustacean thought to be extremely rare, was discovered in large numbers in polluted regions of the Strait of Canso. The shrimp may live deeper than 3 meters in the sediment; burrows are kept open to at least 2.5 meters. Sediment contained in old filled burrows is anomalous in its distribution of particle size and its content of water, organic carbon, and trace elements. These anomalous qualitites affect the geotechnical properties of sediments on the sea floor.
TL;DR: In this paper, a theory of the heat of solution of hydrogen in simple metals is developed and results for the cases of aluminum and magnesium are presented for the case of aluminum, which is treated within the framework of local pseudopotential theory.
Abstract: A theory of the heat of solution of hydrogen in simple metals is developed and results are presented for the cases of aluminum and magnesium. The electronic contribution to the heat of solution is treated within the framework of local pseudopotential theory and is based on linear screening. For the proton contribution it is necessary to use nonlinear theory for the screening of the proton and a convenient framework for this is the density functional formalism with exchange and correlation corrections included approximately. The calculated value of the heat of solution for aluminum is 0.45 eV which compares favorably with the experimental value of 0.66 eV. The result for magnesium, -0.05 eV, is also in reasonable agreement with the experimental value of 0.25 eV bearing in mind that the hydrogen heat of solution is obtained as the difference of two energies of about 15 eV. The energy has also been investigated as a function of the position of the proton in the lattice. Calculated energy barriers are used to estimate proton diffusion parameters.
TL;DR: The Cunningham Roberts report as discussed by the authors investigated how Canadian pump and valve manufacturers' perceptions of customer service offered by their metal suppliers compared with the perceptions of their UK counterparts and concluded that there are substantial disparities between the two countries.
Abstract: Reports on the results of a study carried out in Canada and compares this with an earlier UK study (the Cunningham Roberts report). Investigates how Canadian pump and valve manufacturers' perceptions of customer service offered by their metal suppliers. Compares with the perceptions of their UK counterparts. Concludes that there are substantial disparities between the two countries.
TL;DR: A theory of optimal worst-case design embodying centering, tolerancing, and tuning is presented and two circuits are studied under a variety of different problem situations to illustrate both the benefits to be derived from the approach and the difficulties encountered in its implementation.
Abstract: A theory of optimal worst-case design embodying centering, tolerancing, and tuning is presented. Some simplified problems and special cases are discussed. Projections and slack variables are used to explain some of the concepts. The worst-case tolerance assignment and design centering problem falls out as a special case. Practical implementation requires a reasonable and'relevant number of parameters and constraints to be identified to make the problem tractable. Two circuits, a simple LC low-pass filter and a realistic high-pass filter, are studied under a variety of different problem situations to illustrate both the benefits to be derived from our approach and the difficulties encountered in its implementation.
TL;DR: A critical examination of the data for and against genetic factors in early infantile autism and childhood schizophrenia is presented, finding no strong evidence exists implicating genetics in the development of childhood psychoses that begin before the age of 5.
Abstract: A critical examination of the data for and against genetic factors in early infantile autism and childhood schizophrenia is presented. The extreme rareness of both disorders made analysis difficult. No strong evidence exists implicating genetics in the development of childhood psychoses that begin before the age of 5. Family pedigree data fail to support psychogenic transmission because very few siblings of early onset cases are affected. Biological but not genetic etiological agents are more likely. Genetic factors are implicated in the development of psychoses that begin near pubescence and such factors appear to overlap with those for adult schizophrenia. Reevaluation of the minimum age of onset for adult-type schizophrenia is suggested.
TL;DR: Preerential adsorption of fibrinogen was observed on both surfaces with glass showing the stronger preference.
TL;DR: Severe catheter-related thromboatheromatous lesions were found at necropsy in 33 of 56 infants who had umbilical arterial catheters passed during life, with features suggesting asynchrony of embolic episodes.
Abstract: Severe catheter-related thromboatheromatous lesions were found at necropsy in 33 of 56 infants who had umbilical arterial catheters passed during life. In infants dying within 8 days of insertion of the catheter, varying degrees of thrombosis of the aorta and its major branches were seen. With increasing thrombosis and aging of the thrombus, fatty deposits were seen first within the thrombus, and then in the intima and media. In addition there was evidence of proliferation of medial smooth muscle cells and of disruption of the medial architecture below the thrombus, characterized by the presence of abundant mucopolysaccharide. In infants who survived longer, varying degrees of organization of the thrombus could be traced, leading eventually to raised fibrous plaques with lipid and occasionally calcification. The lesions in the older infants were similar in many respects to experimental thromboatheromatous lesions produced in rabbits, and to some lesions of artheroma occurring spontaneously in humans. A wide variety of embolic phenomena were found, with features suggesting asynchrony of embolic episodes. The presence of thrombotic lesions could not be related to birthweight, Apgar scores at 1 and 5 minutes, age at catheterization, duration of catheterization, underlying disease process, age at death or the presence of hypothermia, acidosis, or anomalies in coagulation tests. There is a need for less hazardous methods of monitoring arterial oxygen tension.
TL;DR: Increased doses of ragweed antigen E, grass pollen extract, and the IgG of sheep antiserum to human IgE (anti-IgE) were injected in intracutaneous tests in humans and LCAR were shown to be a usual sequel to allergic reactions of sufficient intensity.
Abstract: Increased doses of ragweed antigen E, grass pollen extract, and the IgG of sheep antiserum to human IgE (anti-IgE) were injected in intracutaneous tests in humans. With increasing doses of reactants, in individual subjects, there were the expected increases in the sizes of early wheal-and-flare responses; moreover, there was an associated increase in the magnitude and the frequency of late cutaneous allergic responses (LCAR). LCAR were shown to be a usual sequel to allergic reactions of sufficient intensity. In persons with allergic bronchopulmonary aspergillosis, cutaneous responses to Aspergillus fumigatus allergen were compared with responses to other allergens and to anti-IgE; in relation to early wheal-and-flare responses, the corresponding LCAR induced by A. fumigatus were approximately the same size as those induced by the other reactants. Skin reactions induced by the prick test method and by intracutaneous injection were compared; for early responses of given sizes, there were apparently equal tendencies to proceed to LCAR in reactions to allergen in the two types of administration. In one subject, anti-IgE-induced responses in the skin of a forearm with sensory denervation were compared with responses in the other normally innervated forearm. At the denervated site was the expected absence of the early flare but no apparent reduction in LCAR. Similarly, local anesthesia immediately prior to anti-IgE eliminated the flare of the early response but did not prevent the occurrence of a LCAR.
TL;DR: A method is described for the separation of blood and bone marrow leukocytes on the basis of buoyant density, using a discontinuous Ficoll-Hypaque density gradient, which showed cells of the myeloid series were shown to increase in density with maturation.