Showing papers by "McMaster University published in 1979"
TL;DR: The present paper organizes and evaluates selected portions of the time perception literature as mentioned in this paper, with a focus on data and theory concerned primarily with judgments of brief temporal intervals and the role of nontemporal information.
Abstract: The present paper organizes and evaluates selected portions of the time perception literature. Emphasis is on data and theory concerned primarily with judgments of brief temporal intervals. Research concerning the psychophysical law for time, Weber’s law, the time-order error, and the role of nontemporal information is evaluated. This is followed by a consideration of current, quantitatively oriented, theoretical formulations for time perception.
518 citations
TL;DR: In this paper, an analytical expression for the optical absorption coefficient of silicon solar cells over a wide range of temperature, particularly when evaluating the concentration type systems, has been developed for this purpose.
Abstract: The optical absorption coefficient is an important parameter in calculating the performance characteristics of solar cells. For silicon solar cells it is desirable to know the absorption coefficient over the range of 1.1–4.0 eV and over a wide range of temperature, particularly when evaluating the concentration type systems. An analytical (empirical) expression has been developed for this purpose. We have interpreted the available experimental data in terms of three bands of silicon. With our fit, the experimental data can be explained to within an accuracy of 20% and its validity extends from 1.1 to 4.0 eV and over the temperature range of 20–500°K.
236 citations
TL;DR: The relationships among bronchia responsiveness to allergen, bronchial responsiveness to histamine, and cutaneous sensitivity to allrgen were examined in 25 asthmatic subjects.
Abstract: The relationships among bronchial responsiveness to allergen, bronchial responsiveness to histamine, and cutaneous sensitivity to allergen were examined in 25 asthmatic subjects. Bronchial responsiveness to allergen was determined by inhalation tests with 2-fold increasing doses of allergen extract, and was expressed as the provocative concentration producing an early asthmatic response with a 20 % decrease in the forced expiratory volume in one second (allergen PC20). Bronchial responsiveness to histamine was determined in a similar way and was expressed as histamine PC20. Cutaneous sensitivity to allergen was determined by duplicate prick skin tests with doubling concentrations of the same allergen extract used for inhalation, and was expressed as the concentration producing a mean wheal diameter of 2 mm. There was a poor correlation between histamine PC20 and cutaneous sensitivity to allergen (r = −0.03, p > 0.1). There was a good correlation between allergen PC20 and histamine PC20 (r = 0.52, p > 0.02...
214 citations
TL;DR: This paper found that decision difficulty is positively related to the distinctiveness of the memorial record of the initial event and that it is distinctiveness, rather than depth or elaboration, of the memory trace that underlies high levels of memorability.
185 citations
TL;DR: Aging in the rodent is accompanied by a progressive loss of skeletal muscle fibers and the muscle twitch also becomes slower, probably as a result of fibertype conversion from “fast‐twitch” to “slow‐twitch.”
Abstract: Aging in the rodent is accompanied by a progressive loss of skeletal muscle fibers. The muscle twitch also becomes slower, probably as a result of fiber-type conversion from "fast-twitch" to "slow-twitch." The loss of muscle fibers precedes signs of obvious weakness and appears to involve the loss of entire functioning motor units. In the mouse, this loss of motor units correlated with a loss of axons from the innervating nerve trunks.
169 citations
TL;DR: In this article, the structures of the RE TiO 3 perovskites, RE = La, Nd, Sm, Gd, and Y, were solved using single-crystal, automated diffractometer techniques.
167 citations
TL;DR: Pure populations of large, nucleated erythrocytes derived from yolk sac blood islands were obtained during normal fetal mouse development and Embryonic hemoglobins were present in these cells early in gestation, as demonstrated by both biochemical and immunocytochemical techniques.
Abstract: Pure populations of large, nucleated erythrocytes derived from yolk sac blood islands were obtained during normal fetal mouse development. Embryonic hemoglobins were present in these cells early in gestation. Later in gestation, an increasing amount of adults hemoglobin was also synthesized and accumulated in this population of primitive nucleated erythrocytes, as demonstrated by both biochemical and immunocytochemical techniques.
165 citations
TL;DR: In this article, a dispersion of manganese dioxide is used as a weak ion exchanger in the determination of the complexing capacities of natural waters for copper and in the estimation of the stability constants of the complexes formed, at the concentration and pH at which the ligands occur in natural waters.
160 citations
TL;DR: In this article, a high speed Mossbauer fitting program with general applicability is described, which uses transmission integral procedures, full Hamiltonian diagnonalisation for arbitrary spins, magnetic field distribution analysis to the first order, single or polycrystalline intensity calculation for arbitrary (mixed) transitions, and the option to include Goldanskii-Karyagin or texture effects.
Abstract: A high speed Mossbauer fitting programme of general applicability is described. Its main features are the use of transmission integral procedures, full Hamiltonian diagnonalisation for arbitrary spins, magnetic field distribution analysis to the first order, single or polycrystalline intensity calculation for arbitrary (mixed) transitions, and the option to include Goldanskii-Karyagin or texture effects. The programme is designed to maintain a simple logical structure as seen by the user.
143 citations
TL;DR: In this article, a modified model for crack-particle interactions in brittle composites is proposed to account for penetrable obstacles, obstacle shape and secondary crack interactions, which is applied to a glass-unbonded nickel sphere composite system.
Abstract: Previous models for crack-particle interactions in brittle composites are modified to account for penetrable obstacles, obstacle shape and secondary crack interactions. The modified model is applied to a glass-unbonded nickel sphere composite system, the experimental aspects of which were summarized in Part 1. Increases in fracture energy are explained in terms of local crack blunting. It is shown that these results fall, as expected, between those for an entirely sharp crack front and an entirely blunt one.
139 citations
TL;DR: Human platelets that had been preincubated with 5-hydroxy[(3)H]tryptamine and [(32)P]P(i) were stirred with various agents and the radioactivity of platelets separated by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis were measured to suggest that a cyclic AMP-dependent phosphorylation of the 24000- and/or 22000-mol.wts.
Abstract: Human platelets that had been preincubated with 5-hydroxy[ 3 H]tryptamine and [ 32 P]P i were stirred with various agents; the secretion of 5-hydroxy[ 3 H]tryptamine from platelet granules and the radioactivity of platelet [ 32 P]phosphopolypeptides separated by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis were then measured. Exposure of the platelets to collagen fibres or ionophore A23187 selectively increased the phosphorylation of polypeptides with apparent mol.wts. of 47000 (P47) and 20000 (P20) by approx. 3-fold, in association with the release of 5-hydroxy[ 3 H]tryptamine. The 47000-mol.wt. phosphopolypeptide (P47) was clearly separated from platelet actin by the electrophoresis system used. Prostaglandin E 1 , which inhibits platelet function by increasing platelet cyclic AMP, decreased the phosphorylation of polypeptides caused by collagen as well as the release of 5-hydroxy[ 3 H]tryptamine. Prostaglandin E 1 also selectively increased the phosphorylation of distinct polypeptides with apparent mol.wts. of 24000 (P24) and 22000 (P22) by approx. 2-fold. As the phosphorylation reactions caused by collagen are probably mediated by an increase in Ca 2+ concentration in the platelet cytosol and may have a role in the release reaction [Haslam & Lynham (1977) Biochem. Biophys. Res. Commun. 77 , 714–722; (1978) Thromb. Res. 12 , 619–628], we suggest that a cyclic AMP-dependent phosphorylation of the 24000- and/or 22000-mol.wt. polypeptides caused by prostaglandin E 1 may initiate processes that decrease the Ca 2+ concentration in the cytosol, so inhibiting both the Ca 2+ -dependent phosphorylation reactions and the release reaction. Treatment of platelets with prostaglandin E 1 did not inhibit the increased phosphorylation of polypeptides with apparent mol.wts. of 47000 and 20000 (P47 and P20) caused by ionophore A23187, which may therefore short-circuit cyclic AMP-dependent mechanisms that decrease the Ca 2+ concentration in the platelet cytosol. As prostaglandin E 1 did inhibit the release of 5-hydroxy[ 3 H]tryptamine by ionophore A23187, cyclic AMP may also inhibit the release reaction by additional mechanisms.
TL;DR: In this article, it was shown that, for high enough target temperatures, halides tend to develop metallized surfaces, and, as would be expected, there is a concurrent loss of metal at higher temperatures but metallization at lower temperatures.
TL;DR: The close correlation between the level of bronchial responsiveness to histamine and exercise supports the view that release of endogenous chemical mediators is an important determinant of exercise-induced asthma.
Abstract: Bronchial responsiveness to inhaled histamine and exercise was measured in 19 asthmatics. Histamine aerosol was inhaled to determine the provocative concentration producing a 20% fall in forced expired volume in one second (FEV 1 ) (PC 20 ). Exercise was performed on a treadmill and a cycle ergometer; following each procedure the percent fall in the FEV 1 (ΔFEV 1 ) and the exercise lability (percent rise in FEV 1 plus percent fall in FEV 1 ) were calculated. ΔFEV 1 and exercise lability after both forms of exercise were similar. PC 20 correlated with ΔFEV 1 and exercise lability in both forms of exercise; however, the correlation with exercise lability was better. PC 20 was more sensitive in demonstrating bronchial hyperresponsiveness. The close correlation between the level of bronchial responsiveness to histamine and exercise supports the view that release of endogenous chemical mediators is an important determinant of exercise-induced asthma. The treadmill exercise and cycle ergometry protocols were equally effective in producing exercise-induced asthma.
TL;DR: This study investigated the possibility that the functional defect of thrombasthenic platelets may be an inability to become associated with fibrinogen upon exposure to adenosine diphosphate, to degrade platelet membrane glycoproteins II and IIl.
TL;DR: A number of macroscopic and microscopic models which have been proposed for reproducing the forward and reverse flow behavior are discussed in this paper, and some of the strengths and weaknesses of the models have been discussed in the light of experimental data available from quasi-static forward and backward loading tests on a variety of materials.
TL;DR: A second order beam theory which takes into account shear curvature, transverse direct stresses and rotatory inertia is presented in this article, where the governing differential equation is similar in form to the Timoshenko beam equation but contains two coefficients, one of which depends on cross-sectional warping just as does Cowper's expression while the second includes terms dependent on the transversal direct stresses.
TL;DR: In this paper, the authors show that soft-sediment deformation occurs during slumping and flowage of liquefied sand down the megaripple stoss side, and that this liquefaction results from the impact of 0.1-0.3 m high waves breaking against the megaris lee faces.
Abstract: Soft-sediment deformation features occur commonly on parts of intertidal sand bodies in Cobequid Bay, Bay of Fundy. These features are small- to intermediate-sized, slump-like bodies, 1-3 m2 in area and located on the crest and upper stoss side of ebb megaripples. External modification of these slumps indicates that they formed before complete emergence. The deformed cross-bedding within these bodies extends to a depth of 0.15-0.35 m and shows that deformation occurred during slumping and flowage of liquefied sand down the megaripple stoss side. Field evidence and calculations strongly indicate that this liquefaction results from the impact of 0.1-0.3 m high waves breaking against the megaripple lee faces. Neither rapid drawdown of the water level nor earthquake shocks are reasonable alternative explanations.
Indigenous wave activity provides an attractive substitute to tectonism as an explanation of soft-sediment deformation in ancient shallow-water sediments. Slow wave-induced compaction may also account for the relative scarcity of deformation structures in shallow marine sandstones.
TL;DR: A simple method for obtaining the series resistance of solar cells is described and Universal current-voltage characteristics of the solar cells are given to illustrate the effects of series and shunt resistance.
Abstract: Series resistance is an important parameter in solar cell design and fabrication. Methods reported in literature for its determination are not suitable for routine use. We describe a simple method for obtaining the series resistance. Universal current-voltage characteristics of the solar cells are also given to illustrate the effects of series and shunt resistance. We also offer an explanation for the often observed drop in efficiency when small area cells are scaled upward. Cells less than 0.25 cm2 represent the intrinsic potential of any given structure or diode but do not reflect series resistance effects that must be eliminated with larger area cells and the practical problems of griding to allow for current collection.
TL;DR: Porphyria did not develop in the iron-deficient animals, and these animals were also protected from hepatocellular damage and certain other toxic effects of TCDD.
Abstract: The compound 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes hepatocellular damage and porphyria in C57B1/6J mice, among a wide range of toxic effects. We compared the effect of TCDD toxicity in iron-deficient mice with that in mice receiving a normal diet. Porphyria did not develop in the iron-deficient animals, and these animals were also protected from hepatocellular damage and certain other toxic effects of TCDD.
TL;DR: In this article, the vibrational properties of six different polytypes of Pb${\mathrm{I}}_{2}$ crystals have been studied experimentally by means of Raman spectroscopy and x-ray diffraction.
Abstract: The vibrational properties of six different polytypes of Pb${\mathrm{I}}_{2}$ crystals have been studied experimentally by means of Raman spectroscopy and x-ray diffraction. The crystals were prepared either by gel growth or by thermal annealing. The Raman spectra are used to determine features of the phonon dispersion curves, in the crystallographic $c$ direction, which are common to all of the polytypes. The results are correlated with existing information obtained from measurements of Brillouin spectra and inelastic scattering of neutrons and then analyzed within the framework of a six-parameter force-constant model. Thermodynamic data, including new measurements of lattice parameters in the range $100lTl295$ K, are used to discuss anharmonic and two-dimensional contributions to the vibrational properties.
TL;DR: In this article, the Bauschinger effect has been used to study the strain hardening in a two phase alloy, and the back stress at small strains, including its temperature and orientation dependence, has been accounted for using the unrelaxed model proposed by Brown and Clarke.
TL;DR: The role of platelet membrane glycoproteins in platelet survival was further investigated with 51Cr-labeled rabbit platelets from which glycoprotein was cleaved by treatment with chymotrypsin, plasmin, or trypsin this article.
TL;DR: No gradient was found for melatonin, although significantly more 5-hydroxyindoleacetic acid was found in the cisternal samples, which suggests that, in the daytime, melatonin is not released directly from the pineal into the third ventricle, as that would produce a CSF gradient.
TL;DR: Sputtering yields of Ag, Au and Pt have been measured for monatomic and polyatomic ions of P, As, Sb and Bi over the energy range 10-250 keV as mentioned in this paper.
TL;DR: The sulfur contents and sulfur isotope ratios (δ34S) have been measured for samples collected from the Isua area of West Greenland in an effort to place narrower limits on the time of the rise of sulfate respirers during the Precambrian.
TL;DR: Uranium series ages show that the speleothem recovered from an underwater karstic cave near Andros Island in the Bahamas was deposited between 160,000 and 139,000 years before the present, which demonstrates that sea level must have been lowered by at least 42 meters from its present position during this time.
Abstract: Stalagmites have been recovered from 45 meters below sea level in an underwater karstic cave ("blue hole") near Andros Island in the Bahamas. Uranium series ages, corrected for contamination of the sample by young marine carbonate replacements, show that the speleothem was deposited between 160,000 and 139,000 years before the present. This period corresponds to the Illinoian glacial event and demonstrates that sea level must have been lowered by at least 42 meters (allowing for subsidence) from its present position during this time.
TL;DR: Results provide strong support for the contention that current analyses of variable-interval response rates that ignore the inherent interresponse-time reinforcement contingency may be seriously in error.
Abstract: The interresponse-time reinforcement contingencies and distributions of interreinforcement intervals characteristic of certain variable-interval schedules were mimicked by reinforcing each key peck with a probability equal to the duration of the interresponse time it terminated, divided by the scheduled mean interreinforcement interval. The interresponse-time reinforcement contingency was then eliminated by basing the probability of reinforcement on the fifth interresponse time preceding the key peck. Even though distributions of interreinforcement intervals were unaffected by this manipulation, response rates consistently increased. A second experiment replicated this effect and showed it to combine additively with that of mean reinforcement rate. These results provide strong support for the contention that current analyses of variable-interval response rates that ignore the inherent interresponse-time reinforcement contingency may be seriously in error.
TL;DR: It appears that treatment of platelets with chymotrypsin, which removes glycopeptides from membrane glycoproteins, also causes rearrangement of platelet membrane components so that fibrinogen-binding sites become available.
TL;DR: The ultrastructure of myometrial tissues from nonpregnant, pregnant and postpartum sheep was quantitatively examined and the formation of gap junctions correlated with a rise in fetal estrogens, a fall in maternal progesterone and increases in fetal and maternal estrogen/progesterone ratios.
Abstract: The ultrastructure of myometrial tissues from nonpregnant, pregnant and postpartum sheep was quantitatively examined for the presence of gap junctions between smooth musde cells. Serum concentrations of estrone, estradiol and progesterone were determined in some of the sheep prior to and at the time of sacrifice. Gap junctions were not present in any tissue from nonpregnant animals or in tissues of pregnant animals at 74-100 days gestation. Small gap junctions were present in some of the tissues from pregnant animals at 127-132 days gestation. Larger gap junctions were present in increased frequency in animals at term and immediately postpartum. The formation of gap junctions correlated with a rise in fetal estrogens, a fall in maternal progesterone and increases in fetal and maternal estrogen/progesterone ratios. These results are consistent with the hypothesis that the hormonal changes which occur near the end of pregnancy bring about the formation of gap junctions and the activation of the myometrium.
TL;DR: In this article, the authors address the phenomenon of recognition failure from the perspective of a theory in which recognition and recall are assumed to involve independent retrieval processes, and show that even given independent retrieval, measures of recognition success will covary if any traces are lost from storage, simply because such traces are unavailable for any memory test.
Abstract: This paper addresses the phenomenon of recognition failure from the perspective of a theory in which recognition and recall are assumed to involve independent retrieval processes. However, even given independent retrieval, measures of recognition and recall success will covary if any traces are lost from storage, simply because such traces are unavailable for any memory test. In support of the theory, rote learning produced higher covariation between recognition and recall (i.e., fewer recognition failures) than did meaningful elaboration during study. Further, recognition and recall were approximately independent of each other with meaningful elaboration and imagery encoding, regardless of whether the latter involved interactive or separate images. The results of three experiments are discussed in terms of the present “vandal” theory and other theories of recognition failure.