Showing papers by "York University published in 1968"

Weighted kappa: Nominal scale agreement provision for scaled disagreement or partial credit.

Abstract: A previously described coefficient of agreement for nominal scales, kappa, treats all disagreements equally. A generalization to weighted kappa (Kw) is presented. The Kw provides for the incorpation of ratio-scaled degrees of disagreement (or agreement) to each of the cells of the k * k table of joi

Bystander intervention in emergencies: Diffusion of responsibility.

Abstract: Ss overheard an epileptic seizure. They believed either that they alone heard the emergency, or that 1 or 4 unseen others were also present. As predicted the presence of other bystanders reduced the individual's feelings of personal responsibility and lowered his speed of reporting (p < .01). In groups of size 3, males reported no faster than females, and females reported no slower when the 1 other bystander was a male rather than a female. In general, personality and background measures were not predictive of helping. Bystander inaction in real-life emergencies is often explained by "apathy," "alienation," and "anomie." This experiment suggests that the explanation may lie more in the bystander's response to other observers than in his indifference to the victim.

Multiple regression as a general data-analytic system.

Abstract: Techniques for using multiple regression (MR) as a general variance-accounting procedure of great flexibility, power, and fidelity to research aims in both manipulative and observational psychological research are presented. As a prelude, the identity of MR and fixed-model analysis of variance/covariance (AV/ACV) is sketched. This requires an exposition of means of expressing nominal scale (qualitative) data as independent variables in MR. Attention is given to methods for handling interactions, curvilinearity, missing data, and covariates, for either uncorrelated or correlated independent variables in MR. Finally, the relative roles of AV/ACV and MR in data analysis are described, and the practical advantages of the latter are set forth.

The structure and function of the synaptinemal complex inLilium longiflorum sporocytes

Abstract: The development of meiotic prophase in pollen mother cells ofLilium longiflorum is presented through photomicrographs of squashes and sections and through electron micrographs of thick and thin sections. Emphasis is placed on the first appearance of axial cores, the participation of axial cores in the formation of synaptinemal complexes, the fine structure of the complex and the fate of the complex at the end of pachytene. It is shown that axial cores are formed in early meiotic prophase chromosomes and that the two axial cores of a set of homologous chromosomes participate in the formation of a synaptinemal complex. It is proposed that the transverse filaments of each axial core meet and interdigitate and so produce the transverse filaments of the complex. It is shown that the complex is axial to the pachytene bivalent and that the association of the complex with chromosomal material is terminated at the end of pachytene. The pairing affinity of the cores in homologous and non-homologous chromosome associations is discussed. The zygotene stage is defined in terms of the occurrence of synaptinemal complexes and the attachment of the nucleolus to the nuclear membrane during this stage is noted.

Methods for Detecting Weak Light Signals

Abstract: Theoretical and experimental evaluation of three low-level photodetection techniques, namely, lock-in, noise-voltage, and electron-pulse counting are presented. The 992 cm−1 Raman band of benzene excited by a 4.2-mW He–Ne laser operating at 6328 A provided a weak light signal which was detected by an EMI 9558 A, cooled photomultiplier. The electron-pulse-counting method employing a pulse-height discriminator was found to be superior to the other methods with regard to both signal sensitivity and signal-to-noise ratio.

Propranolol and isosorbide dinitrate synergism in angina pectoris.

Abstract: A remarkable synergism has been found to exist between propranolol, a beta adrenergic receptor blocking agent, and isosorbide dinitrate. The phenomenon was observed in a series of 28 selected patients with severe and refractory forms of angina pectoris and was manifested by striking improvement in pain experience, ischemic electrocardiographic patterns, and capacity for exercise. Further studies are indicated to determine the range of applicability of propranolol-nitrate therapy in angina pectoris, in asymptomatic coronary insufficiency and in programs of physical reconditioning for coronary patients. Data are also necessary to determine the influence of this form of treatment on the ultimate prognosis in various types of coronary heart disease. Persistence of striking benefit on continued treatment affords promise of long-term relief for many patients presently unresponsive to traditional management.

Conformational studies of proteins with aromatic side-chain effects

Abstract: We present here a brief analysis of ultraviolet isotropic absorption and related circular dichroism of the n–π* and π–π* transitions for the peptide (amide) chromophore in the 185–240 mμ region. Investigations by ultraviolet absorption and circular dichroism techniques on natural amino acids with aromatic chromophores in their side chains are also reported. By taking into account both the peptide and aromatic transitions we discuss the conformational studies of proteins with aromatic side-chain effects. Our attention is largely focused on the optical rotatory dispersion and circular dichroism spectra of these proteins in the near ultraviolet region, where characteristic aromatic side-chain bands occur. The 185–240 mμ region is also discussed when evidence exists of overlapping Cotton effects of aromatic and peptide groups.

Conformational aspects of polypeptides. XXV. Solvent and temperature effects on the conformations of copolymers of benzyl and methyl L-aspartate with nitrobenzyl L-aspartate.

Abstract: A series of copolymers of β-p-nitrobenzyl L-aspartate with β-benzyl L-aspartate and with β-mcthyl L-aspartatc in helix-supporting and helix-breaking conditions have been reexamined by using ultraviolet isotropic, absorption, optical rotatory dispersion, and circular dichroism techniques. Many different conformations are apparent, depending on solvent and temperature. Chloroform, trifluoroethanol, and methylene dichloride support the left-handed helical conformation of the copolymers containing less than about 20 mole-% nitroaromatic residues and the right-handed helical conformation of the copolymers containing more than approximately 30 mole-% nitroaromatic residues. In trifluoroacetic acid all the copolymers are in a random-coil conformation. In hexa-fluoroacetone trihydrate and in trimethyl phosphate, the copolypeptides with low nitroaromatic residues content are predominantly in a disordered conformation, while those with high nitroaromatic residues content show a right-handed helical array. Reversible helix-ramlom-coil transitions are observed with increasing temperature in trimethyl phosphate. An example of right-handed-left-handed helix reversible transition with temperature is reported in a chloroform-trimethyl phosphate (2:1) mixture. Nitrobenzyl-nilrobenzyl side-chain interactions in chloroform, but not in trifluoroacetic acid or in trimethyl phosphate, have been confirmed. For the first time we report the circular dichroism spectra in which the n-π* peptide band of a left-handed helical conformation is almost completely evident.

Franck-Condon factors for ionizing transitions of O2, CO, NO and H2 and for the NO+(A 1-ΣX 1Σ) band system

Abstract: The quantitative use of Franck-Condon factors in radiative, excitation and ionization transitions of molecules is discussed. Franck-Condon factor arrays are presented for ionizing transitions of O2, CO, NO and H2 and for the NO+ (A 1Σ-X 1Σ) band system.

Decreased uterotropic potency of oral contraceptives in rats pretreated with phenobarbital.

Abstract: Treatment of immature female rats with phenobarbital for 4 days inhibits the uterotropic action of synthetic estrogens such as ethynyl estradiol, ethynyl estradiol-3-methyl ether (mestranol) and diethylstilbestrol. Treatment of rats with as little as 0.25 mg of phenobarbital/kg twice daily for 4 days causes a 33% inhibition in the uterotropic action of a 1 μg oral dose of ethynyl estradiol-3-methyl ether. The inhibitory effect of phenobarbital administration on the action of diethylstilbestrol-3H is paralleled by decreased radioactivity in the uterus and by increased levels of NADPH-dependent enzymes in liver microsomes that metabolize diethyl-stilbestrol. Studies on the estrogenic activity of synthetic progestational steroids in rats revealed that the administration of norethindrone and norethynodrel increases the uterine wet weight and this effect is inhibited by pretreatment with phenobarbital. (Endocrinology 83: 149, 1968)

Photophysical and photochemical effects of dye binding.

Abstract: — A discussion is given of the photophysical and photochemical consequences of the binding of dyes and of pigments of biological importance to polymeric substrates. The modification of the photochemical properties induced by dye binding can in large part be ascribed to the known changes in photophysical properties of dyes engendered by such interactions. Principally, these involve enhanced formation of metastable species of dye molecules and decreased opportunity for self-quenching. In photochemical terms, dye binding thus enhances susceptibility to photoreduction, causes an increase in the quantum yield of photoreduction with increasing concentration of bound dye, and induces enhanced ability to act as a sensi-tizer in photoreduction. Paradoxically, dye binding decreases the ability of the bound dye to act as a sensitizer in photoxidation.

Brillouin Scattering in Birefringent Media

Abstract: The theory of Brillouin scattering is extended to incorporate birefringence. The necessary modifications to the Bragg laws are derived by the methods of physical optics. An integral equation method is used to calculate intensities of the first-order lines scattered by longitudinal and transverse acoustic waves in an infinite slab of birefringent crystal. This calculation also differs from those of previous authors in taking full account of internal reflection. Depletion of the incident beam is accounted for. No restriction is made to acoustic propagation parallel to the crystal faces. The intensity formulas for various cases of acoustic mode and incident optical polarization are found to differ in geometrical structure, and the differences can alter the intensities substantially.

Further studies on the histidine-histamine relationship in vivo: effects of endotoxin and of histidine decarboxylase inhibitors.

Abstract: 1 . Mice were injected with (14C)-l-histidine, killed at various intervals, and tissues assayed for (14C)-histamine. In some cases free (14C)-l-histidine and total (14C) were also determined. 2 . Removal of stomach, the most active histamine-forming tissue, failed to reduce the (14C)-histamine content of any tested tissue; (14C)-histamine concentrations in lung and muscle of gastrectomized mice were higher than in sham-operated controls. 3 . In mice pretreated with endotoxin and subsequently injected with (14C)-l-histidine, the (14C)-histamine content of liver, lung and muscle was markedly higher than in controls. The increased concentrations of (14C)-histamine in endotoxin-pretreated mice seemed to reflect a greater rate of formation; they could be attributed neither to changes in tissue concentration of (14C)-l-histidine, to increased uptake from other tissues, nor to impaired ability to inactivate histamine. 4 . Results of studies on in vivo effectiveness of several histidine decarboxylase inhibitors are reported. 5 . The following conclusions are supported by the evidence presented: (a) in stressed mice, those tissues which show activation of histidine decarboxylase also show increased ability to form histamine in vivo; (b) tissue histamine is largely formed locally; (c) histidine decarboxylase inhibitors are highly effective in blocking histamine formation in mast cells and in stomach, but do not normally reach the locus of an inducible form of histidine decarboxylase; (d) the inducible form of histidine decarboxylase in liver may be located in phagocytic microvascular endothelial cells; (e) in conditions favouring near-maximal activation of histidine decarboxylase, the histamine-methylating enzyme of liver and diamine oxidase of intestine showed no inducible characteristics; (f) blood histamine concentrations do not accurately reflect changes in tissue histamine formation.

Coupled-Channel Calculation of C-12-Neutron Scattering

Abstract: Coupled-channel calculations are described for the interaction between a neutron and ${\mathrm{C}}^{12}$. Emphasis is placed on the incident-energy region between 0 and 5 MeV, although the bound states are also calculated. Precise fits to total, elastic differential, and polarization cross sections are obtained. Comparisons with other treatments of the $A=13$ system are made, and the differences are discussed, in particular the meaning of the weak-coupling approximation. Deficiencies in the present method of calculation are also discussed.

Anchor effects using numerical estimates of simple dot patterns

Abstract: Shifts due to anchor stimuli using absolute judgments have been ascribed to “semantic” and “scale modulus” changes. To test this explanation, random dot patterns of 10, 12, 14, 16 and 18 dots were exposed for 0.30 sec with anchors of 4, 13 or 32 dots preceding each of the stimuli. In the control only the series of stimuli were judged. It was found that numerical estimates of the number of dots increased with small anchor, decreased with large anchor, and were not significantly changed with anchor in the vicinity of AL. These results exactly parallel those found using methods of absolute and comparative ratings and hence cannot be ascribed to semantic shifts especially in view of the fact that independent groups of Ss served in the four anchor and control conditions. Since the anchor effects were significant but not so large that they can be ascribed to change of scale modulus this theory must also be rejected. The AL model seems to offer the simplest and most unitary explanation of these as well as many other results obtained with different types of stimuli and different methods of judging.

Patterns of hemorrhage into pancreatic pseudocysts

Abstract: Major hemorrhage into pancreatic pseudocysts occurs infrequently. Three patients are presented illustrating individual clinical and pathologic patterns, yet all survived this catastrophe. Prompt surgery is necessary if rupture is suspected or if anemia and shock supervene in a patient known or suspected of having a pancreatic pseudocyst.