Showing papers by "Queen's University published in 1971"
TL;DR: In this paper, a general model is proposed which allows for a smooth transition from one linear regime to the other, accomplished by a curve incorporating a transition parameter, and a Bayesian estimation procedure is used to determine the plausibility of different parameter values.
Abstract: SUMMARY For experimental data which appear to behave according to two different distinct linear relationships, a general model is proposed which allows for a smooth transition from one linear regime to the other. The transition is accomplished by a curve incorporating a transition parameter. The special case of two intersecting straight lines is included in this model. A Bayesian estimation procedure is used to determine the plausibility of different parameter values. The analysis procedure may be extended to any number of join points and for any linear intersecting functions.
456 citations
TL;DR: A new classification of dormancies in insects is proposed on the basis of the evolutionary nature of dormancy, its synchronization with the aetiology of the species for their phenological advantage, the nature of ecological adversity, and the consequent physiological and biochemical adjustments.
Abstract: A new classification of dormancy in insects is proposed on the basis of the evolutionary nature of dormancy, its synchronization with the aetiology of the species for their phenological advantage, the nature of ecological adversity, and the consequent physiological and biochemical adjustments. The roles of the above factors in the induction and termination of dormancies are discussed. The inadequacies of all the previous systems of describing various conditions of dormancy are pointed out.All instances of dormancy are divided into three major groups: hibernation, aestivation, and athermopause. Each of these classes is further subdivided into three categories representing a sequence of evolutionary adaptations: quiescence, oligopause, and diapause, in that order of evolutionary development. Depending upon the physiological condition of diapausing individuals or populations, two diapause states are recognized: teleodiapause and ateleodiapause. Each term is defined and discussed with examples.
237 citations
210 citations
TL;DR: In this article, a review of the solution of the linear regulator problem for linear systems with state and control-dependent disturbances is presented, both the finite and infinite terminal time cases are treated.
Abstract: A review of the solution of the linear regulator problem for linear systems with state- and control-dependent disturbances is presented. Both the finite and infinite terminal time cases are treated. The solution to the complete state feedback case is given in detail and that for the output feedback case is noted. The general conclusion is that control-dependent noise calls for conservative control (small gains) while state-dependent noise calls for vigorous control (large gains). Of course it is the degree of this behavior that is important and this is given explicitly by the algorithms in this paper.
163 citations
TL;DR: Evidence is presented that normal growth of axillary shoots occurs even when all mineral ions have to be obtained by translocation from the lower compartment.
Abstract: A B S T R A C T Rooted stems of three aquatic species were cultured in a two-compartment apparatus which allowed the upper and lower portions of the stem to be kept in different nutrient solutions. p32 was supplied to either the upper or lower compartment. At the end of a 10-day growth period, the specific activity of phosphate was determined in axillary shoots which developed during the course of the experiment from buds in the upper compartment. The results indicated that most of the phosphate in these shoots was not absorbed from the ambient medium but was derived from the rooted stem base in the lower compartment (over 90 % in Myriophyllum brasiliense, 59 % in M. spicatum, and 74 % in Elodea densa). These results give a very different but probably more accurate picture of phosphate absorption in rooted aquatic vascular plants than short-term experiments, in which phosphate is readily taken up from the ambient medium by leaves of M. spicatum and E. densa. In M. brasiliense the amount of phosphate translocated is related to the mass of roots present. Evidence is presented that normal growth of axillary shoots occurs even when all mineral ions have to be obtained by translocation from the lower compartment.
150 citations
TL;DR: In this paper, the authors investigated the influence of Fermi-surface geometry on the lifetime of an electron due to interactions with other electrons, and performed a calculation of the energy and temperature-dependent lifetime.
Abstract: In order to investigate the influence of Fermi-surface geometry on the lifetime of an electron due to interactions with other electrons, we have performed a calculation (using Fermi's "Golden Rule") of the energy- and temperature-dependent lifetime of an electron on a cylindrical Fermi surface. At zero temperature, the dominant energy dependence of the inverse lifetime or the decay rate is ${\ensuremath{\epsilon}}^{2}|\mathrm{ln}\ensuremath{\epsilon}|$ for small values of the parameter $\ensuremath{\epsilon}$ which is the electron energy relative to the Fermi energy $\ensuremath{\mu}$ measured in units of $\ensuremath{\mu}$. At finite temperatures the decay rate leads to an electrical resistivity proportional to ${T}^{2}|\frac{\mathrm{ln}\mathrm{kT}}{\ensuremath{\mu}}|$ instead of the ${T}^{2}$ dependence characteristic of a spherical Fermi surface. In addition, the similar calculation (using Fermi's "Golden Rule") for a spherical Fermi surface has been done exactly at zero temperature. The magnitude of the correction to the well-known ${\ensuremath{\epsilon}}^{2}$ term has been obtained. Furthermore, in an appendix, written with N. D. Mermin, the dominating influence of the density of states on the wave-vector dependence of the susceptibility is demonstrated.
139 citations
TL;DR: The high specific radioactivity of the (14)CO(2) evolved during photosynthesis or in the early period of flushing in CO(2)-free air showed that the substrate for light respiration was an early product of photosynthesis.
Abstract: Single attached leaves of sunflower (Helianthus annus L. "Mennonite") were supplied (14)CO(2) of constant specific radioactivity in gas mixtures containing various CO(2) and O(2) concentrations. The (14)CO(2) and CO(2) fluxes were measured concurrently in an open system using an ionization chamber and infrared gas analyzer.The rate of photorespiration (5.7 +/- 0.3 mg CO(2).dm(-2).(-1)) during photosynthesis in 21% O(2) at 25 C and 3,500 footcandles was over three times the rate of dark respiration and was independent of CO(2) concentrations from 0 to 300 mul/l. The steady rate of CO(2) evolution into CO(2)-free air was about 30% lower. Low oxygen (1%) inhibited both (14)CO(2) and CO(2) evolution, both during photosynthesis and in CO(2)-free air in the light.At 300 mul/l CO(2) apparent photosynthesis was inhibited 41% by 21% O(2). Two-thirds of the inhibition was due to the inhibition of true photosynthesis by oxygen and one-third due to the stimulation of photorespiration. At 50 mul/l CO(2), where the percentage inhibition of apparent photosynthesis by 21% oxygen was 92%, photorespiration accounted for two-thirds of the total inhibition.The rate of (14)CO(2) uptake by the leaf decreased about 30 seconds after the introduction of (14)CO(2), indicating that (14)CO(2) was rapidly evolved from the leaf. The rate of (14)CO(2) evolution increased rapidly with time, the kinetics depending on the CO(2) concentration. The high specific radioactivity of the (14)CO(2) evolved during photosynthesis or in the early period of flushing in CO(2)-free air showed that the substrate for light respiration was an early product of photosynthesis. From the measurement of (14)CO(2) and CO(2) evolution into CO(2)-free air over a longer time period it was apparent that at least three compounds, each of decreased (14)C content, could supply the substrate for light respiration.Based on a consideration of the specific radioactivity of (14)CO(2) evolved under a variety of conditions, it is suggested that total CO(2) evolution in the light or photorespiration is composed of two processes, dark respiration and light respiration. Light respiration is a process that only occurs in the light, persists for some time on darkening, and metabolizes substrates that are quite different from those of dark respiration.
137 citations
TL;DR: The most striking findings relate to sexuality and in particular extra-marital activity; the engagement in sexual relationships with multiple partners ; greater sexual drive and the greater frequency of venereal disease among the cancer group of patients.
127 citations
TL;DR: The morphogenesis of the extra-embryonic circulatory system of the chick was studied by light and electron microscopy, from precirculatory stages until the beginning of the definitive circulation, which leads to completion of the adult vascular structure.
Abstract: The morphogenesis of the extra-embryonic circulatory system of the chick was studied by light and electron microscopy, from precirculatory stages until the beginning of the definitive circulation. Early mesodermal migrations of prospective vasoformative cells and formation of blood islands take place with minimal morphologically expressed cytodifferentiation. The earliest mesodermal clusters are not syncytial. Formation of vascular lumina is not due to lysis of central cells. Undifferentiated mesenchyme possesses the capacity to establish complex junctional devices at points of contact with like cells. The first formed blood islands show intimate relationships with endoderm. The initial capillary network is sinusoidal in type, the endothelium being unsupported by a basement membrane. The major vitelline vessels acquire a more complex anatomy but the capillaries retain this simple pattern throughout the period studied. Several phases in the histogenesis of vitelline vessels are recognized, which could be correlated with the known progression of arterial pressure patterns. Continuing differentiation and mesenchymal investment of vascular walls, after stages 22–23 of Hamburger and Hamilton ('51), in correspondence with the last sustained pressure elevation, leads to completion of the adult vascular structure.
116 citations
TL;DR: The results suggest that in Fe 2 Mn is absorbed largely by diffusion, whereas in FeD, Mn absorption in the proximal intestine is increased by the enhanced activity of a system which is dose-saturable and can be competitively inhibited by Fe.
111 citations
TL;DR: It is concluded that nitroglycerin acts primarily by reducing left ventricular oxygen requirements and that this reduction is effected primarily through a reduction inleft ventricular volume.
Abstract: Hemodynamic indexes and coronary blood flow were measured at rest and during exercise before and after nitroglycerin in 15 patients with coronary artery disease. Angina developed in 7 of these patients during the initial exercise period and was associated with an increase in left ventricular end-diastolic pressure to 32.9 mm Hg without an appropriate increase in left ventricular stroke work. During exercise after nitroglycerin only 2 of these patients experienced angina and the hemodynamic response to exercise was normal. In the patients without angina minor alterations in ventricular performance occurred during the initial exercise period, and these were similarly reversed with nitroglycerin. Coronary blood flow measured by the 85 krypton technique was normal at rest and during exercise in both groups of patients before and after the administration of nitroglycerin. Since there was no demonstrable effect on coronary blood flow, we conclude that nitroglycerin acts primarily by reducing left ventricular oxygen requirements and that this reduction is effected primarily through a reduction in left ventricular volume.
TL;DR: Hemodynamic studies at rest and during exercise were carried out in patients with chronic obstructive lung disease, nine of whom had cor pulmonale, and the right ventricular end-diastolic pressure which was normal at rest reached abnormal levels during exercise.
TL;DR: In individual patients the pacing ventricular function curve appears useful in assessment of the effect of interventions that augment or depress ventricular performance.
Abstract: With the technique of right atrial pacing, left ventricular function was assessed in 21 normal subjects and in 13 patients with elevated left ventricular filling pressures. Since cardiac output does not change significantly with atrial pacing, the stroke volume decreases as an inverse function of the pacing rate. Stroke volume can thus be varied over a wide range, and by simultaneous measurement of left ventricular end-diastolic pressure, pacing ventricular function curves can be obtained. The calculated average slope for the ventricular function curve relating stroke volume index to left ventricular end-diastolic pressure was steeper in the normal subjects than in the group with elevated left ventricular end-diastolic pressure, but considerable overlap occurred between the groups. However, in individual patients the pacing ventricular function curve appears useful in assessment of the effect of interventions that augment or depress ventricular performance.
TL;DR: Nodulated plants of field pea were grown for 4 weeks in a range of constantly maintained levels of nitrate labelled with N15 to study the plant response to nitrate, and the distribution of the nitrogen assimilated from nitrate and from the atmosphere was assessed.
Abstract: Nodulated plants of field pea (Pisum arvense L.) were grown for 4 weeks in a range of constantly maintained levels of nitrate labelled with N15. The total and labelled nitrogen in soluble and insoluble fractions of different parts of the treated plants were determined, and from such measurements the distribution of the nitrogen assimilated from nitrate and from the atmosphere was assessed.
TL;DR: The cercaria of Schistosoma mansoni resembles that of the adult in its basic organization but differs considerably in detail, and three morphologically distinct types of penetration gland can be distinguished.
Abstract: The tegument of the cercaria of Schistosoma mansoni resembles that of the adult in its basic organization but differs considerably in detail. The outer level of the cercarial tegument is thinner and contains several types of inclusion not found in the adult. Only rod-like bodies are characteristic of both stages. Although the cercarial spines are smaller than those of the adult they possess an identical substructure. The uniciliate sensory structures of the cercaria differ from those of the adult in that the cilium of the cercarial structure is not ensheathed in tegumental material. A second type of sensory structure bearing several cilia is located at the anterior tip of the cercaria. Three morphologically distinct types of penetration gland can be distinguished and the content of each is described.
TL;DR: In this article, the flow stress-dislocation density relationship was determined for copper single crystals deformed at room temperature, and the results were in good agreement with previous work on multiple-slip single crystals and polycrystalline material by Livingston and Bailey(7) respectively.
TL;DR: In this paper, auteur evoque brievement les trois lignes de recherches qui attribuent la cause de l'illusion de Muller-Lyer.
Abstract: L'auteur evoque brievement les trois lignes de recherches qui attribuent la cause de l'illusion de Muller-Lyer, respectivement a un facteur de differentiation perceptive, a un facteur ecologique (milieu “charpente” ou non), a un facteur de pigmentation retinienne. Il examine quelle est la part de chacun de ces facteurs dans les resultats de 10 echantillons de sujets, qui varient selon la culture et l'ecologie. C'est l'hypothese de pigmentation retinienne qui semble la mieux confirmee, la moins confirmee etait l'hypothese ecologique et le role de la differentiation perceptive ne recevant aucune confirmation de culture en culture.
TL;DR: In this article, it is suggested that partitioning the total energy of the system into attractive-dominant and repulsive-domantinant interactions provides the most helpful framework for the construction of a physical picture of the Edward-Lemieux effect.
Abstract: Many data, collected from the literature, support the postulation of two general rules which describe the static and dynamic results of having in a molecule or generating in an intermediate adjacent electron pairs and/or polar bonds. In disagreement with current chemical intuition, structures which contain the maximum number of gauche-interactions between lone electron pairs or polar bonds represent energy minima and, frequently, the lowest minima. The stereochemical implications of the phenomenon are discussed, along with possible physical explanations. It is suggested that partitioning of the total energy of the system into attractive-dominant and repulsive-dominant interactions provides the most helpful framework for the construction of a physical picture of the phenomenon. The total energy and its components can be obtained by ab initio molecular quantum mechanical calculations.The only apparent exception to the phenomenon that has been found corresponds to a polar bond adjacent to two lone pairs (as in the case of two hetero-atoms attached to the same carbon atom). This exception, here termed the Edward–Lemieux effect, has been examined theoretically by an ab initio(Hartree–Fock) calculation using fluoromethanol as a model compound. The calculation has reproduced the Edward–Lemieux effect; the stable conformation has the C–F bond trans to one ‘electron pair’ and gauche to another, and the conformation in which the C–F bond bisects the ‘electron pairs’ is the energy maximum. The partitioning of the total energy into its components of attraction and repulsion and comparison of the results with other systems for which barriers to internal rotation have been obtained by ab initio methods reveals a similarity between fluoromethanol, hydrazine, hydroxylamine, and hydrogen peroxide. An interpretation of this result is provided in which an early suggestion by Lemieux and Chu is supported and the concept of ‘rabbit-ears’ is not.
TL;DR: The responses of various groups of Gram negative, yellow pigmented rods constructed on the basis of classical criteria to a wide range of cultural and biochemical features were examined.
Abstract: SUMMARY: The responses of various groups of Gram negative, yellow pigmented rods constructed on the basis of classical criteria to a wide range of cultural and biochemical features were examined. The occurrence of a wide area of slime surrounding true growth with isolates which may spread but did not glide is described. The correlation between the classical groups and divisions suggested on the basis of pigment absorption curves was examined.
TL;DR: In this paper, the X-ray form factor F(μ) is shown to be proportional to the convolution of the momentum space charge density matrix, and it is shown that the form factor is a function of the density matrix.
TL;DR: Alkaline phosphatase activity varied 20-fold, lowest activity with excess phosphate light-limited cells and the highest activity with cells grown in the presence of 15 mM KNO3, and there was no correlation between hot water soluble phosphate of cells and alkaline phosph atase activity.
Abstract: Anabaena flos-aquae was grown in chemostats with phosphate-limiting growth and dilution rate of 0.015–0.03 h-1. The yields of cells were dependent on dilution rate and a two-fold increase obtained by growth in the presence of 15 mM KNO3. Alkaline phosphatase activity varied 20-fold, lowest activity with excess phosphate light-limited cells and the highest activity with cells grown in the presence of 15 mM KNO3. There was no correlation between hot water soluble phosphate of cells and alkaline phosphatase activity.
TL;DR: It is proposed that a child is particularly vulnerable when a depressive illness is superimposed upon a constellation of parental factors which can be recognized and specified and lead to the prevention of this type of crime.
Abstract: Although it is common practice to try to assess the risk of suicide in depressed patients the possibility of homicidal tendencies is often overlooked. Homicidal acts are frequently directed towards...
TL;DR: The behavior of the neurosecretory system of Rhodnius throughout the final molting cycle is inferred from changes in the numbers of the five cell types, and an interpretive model is constructed from analysis of the interconversions among the cell types.
TL;DR: The authors showed that colchicine does not mediate the augmented release of ACTH induced by releasing factor activity and that the mechanism of augmented release induced by high K+ differs from that governing the release of rat hypothalamus-stalk-median eminence extract.
Abstract: The addition of colchicine (10-5M) to adenohypophyses incubated in Krebs-Ringer bicarbonate suppressed the augmented release of ACTH induced by a 5-fold increase in K+ concentration. However, this concentration of colchicine was without effect on the augmented release induced by the addition of a crude acid extract of rat hypothalamus-stalk-median eminence (HSME). Since colchicine binds to and blocks the contractile microtubular system which might be involved in the translocation of hormone-containing granules within the cell, these findings suggest (a) that this system does not mediate the augmented release of ACTH induced by releasing factor activity and (b) that the mechanism of augmented release of ACTH induced by high K+ differs from that governing the release induced by the HSME extract. (Endocrinology 89:408,1971)
TL;DR: This paper examines spatial search behavior related to intra-urban migration by identifying and measuring distance, directional, and sectoral spatial biases, for which an algorithm is presented that employs a map transformation and standard ellipse analysis.
Abstract: This paper examines spatial search behavior related to intra-urban migration. Its approach is to draw upon related studies to derive expectations with regard to search patterns, and to test these through empirical analysis. This involves identifying and measuring distance, directional, and sectoral spatial biases, for which an algorithm is presented that employs a map transformation and standard ellipse analysis.
TL;DR: The visual span of apprehension for random letter and digit sequences, approximations to English sequences and non-symbolic line stimuli was measured in patients with unilateral cerebral lesions and the left hemisphere group was significantly impaired relative to the right hemisphere group and a control group on all three types of visual span task.
Abstract: The visual span of apprehension for random letter and digit sequences, approximations to English sequences and non-symbolic line stimuli was measured in patients with unilateral cerebral lesions. T...