Showing papers by "University of Sydney published in 1971"
TL;DR: The speed/velocity distribution functions have been measured for three crowd fluids in the gaseous phase and good agreement is obtained with Maxwell-Boltzmann theory except for a significant deviation near the frequency mode of each distribution.
Abstract: The speed/velocity distribution functions have been measured for three crowd fluids in the gaseous phase. Good agreement is obtained with Maxwell-Boltzmann theory except for a significant deviation near the frequency mode of each distribution. This is attributed to sexual inhomogeneity.
592 citations
TL;DR: The identity-by-descent approach is extended to derive the distribution of the length of homozygous chromosome segment surrounding a locus which is identical by descent, and it is suggested that a general theory of stability of the genotype in small populations might be based on parameters such as this.
542 citations
TL;DR: In this paper, an experimental study of the internal layer which grows down-stream from a rough-to-smooth surface change is presented, which is essentially different from that studied by Antonia & Luxton (1971 b) for the case of a smooth-torough perturbation.
Abstract: An experimental study of the structure of the internal layer which grows down-stream from a rough-to-smooth surface change shows it to be essentially different from that studied by Antonia & Luxton (1971 b) for the case of a smooth-to-rough perturbation. The rate of growth of the internal layer is less than that for the smooth-to-rough step and it appears that the more intense initial rough-wall flow dictates the rate of diffusion of the disturbance for a considerable distance. Inside the internal layer the mixing length I is increased relative to the equilibrium distribution I = KY. A turbulent energy budget shows that the advection is comparable with the production or dissipation, whilst there seems to be some diffusion of energy into the internal-layer region close to the wall. The boundary layer, as a whole, recovers much more slowly following a rough-to-smooth change than following a smooth-to-rough change, and at the last measuring station (16 boundary-layer thicknesses from the start of the smooth surface) the distributions of mean velocity and Reynolds shear stress are far from self-preserving.
403 citations
218 citations
TL;DR: It is suggested that inherited insensitivity of the respiratory centre in New Guineans (and in some Caucasians) leads to unusually severe disturbances of blood gases in chronic lung disease and is supported by published data relating arterial PCO2 and the severity of airways obstruction in New guineans.
217 citations
TL;DR: It is shown that in a simple mathematical model the criteria for isolated single-level stability and for total web stability are not identical, but they tend to be similar, so that usually stability at one level goes with stability (or instability) of the whole.
Abstract: First, we consider a simple mathematical model for a many-predator-many-prey system, and show it to be in general less stable, and never more stable, than the analogous one-predator-one-prey community. This result would seem to caution against any simple belief that increasing population stability is a mathematical consequence of increasing multispecies complexity. Second, we take up the question of the relation between stability in any one trophic level by itself and stability of the total trophic web. We find that in a simple mathematical model the criteria for isolated single-level stability and for total web stability are not identical, but they tend to be similar, so that usually stability (or instability) at one level goes with stability (or instability) of the whole. It is possible, however, to construct examples where either stability at one level occurs in an overall unstable system, or alternatively instability at one level goes with total web stability. This model points the way to a synthesis of the diverse views that have been expressed on this subject.
202 citations
TL;DR: In this paper, the authors show that most of the world's marginal seas date from Early to Late Tertiary and appear to have been formed by rifting, and that they are usually bounded on the oceanic side by andesitic volcanic arcs and trenches.
195 citations
TL;DR: In this article, a general purpose consolidometer for studying the one-dimensional consolidation behavior of soils is described, which can be used to measure residual pore pressures and swell pressures during back pressure saturation at constant volume.
Abstract: A new general purpose consolidometer for studying the one-dimensional consolidation behavior of soils is described. The test specimen can be loaded incrementally, as in the conventional test, at a constant rate of stress, or at a constant rate of strain. The apparatus can also be used to measure residual pore pressures and swell pressures during back pressure saturation at constant volume. Pore pressures are measured at the impervious base, and free drainage occurs from the top surface. A general solution to the consolidation equation is derived for conditions of constant rate of strain assuming constant \Ic\dv\N. While particular solutions are given for both a linear soil having constant \Im\dv\N and a nonlinear soil with constant \IC\dc\N, it is shown that for most purposes the linear solution is sufficiently accurate for interpreting constant rate of strain (CRSC) test results. The CRSC test is shown to be a simpler and much faster method for measuring the consolidation characteristics of soils than is the conventional test.
144 citations
TL;DR: In this article, the authors used the Goldstack interferometer at 3.8 cm (d/lambda = 10 to the 8th power) to observe the fringes from 31 compact radio sources, including eight known or suspected galaxies and 20 unknown or suspected QSSs.
Abstract: Observation of fringes from 31 compact radio sources, including eight known or suspected galaxies and 20 known or suspected QSSs, by using the Goldstack interferometer at lambda = 3.8 cm (d/lambda = 10 to the 8th power). Fringe visibility curves were obtained for nine sources showing structure on a scale of .001 sec of arc, and simple models are fitted to the data. Results for 3C 273 and 3C 279 are compared with data taken by Knight et al. (1971) at an earlier epoch. The apparent changes in brightness distribution of 3C 273 and 3C 279 are difficult to explain.
144 citations
TL;DR: It is suggested that the symbiotes resemble the Rickettsiaceae and may have arisen from a member of this group, but it is also possible that they arose from free-living bacteria rather than from non-symbiotic rickettsiae.
124 citations
01 Nov 1971
TL;DR: In this paper, the incipient flocculation of sterically stabilized dispersions has been investigated and it is shown that dispersions which undergo flocculations on heating must be enthalpically stabilized, at least immediately below the incipitiative floculation temperature; conversely, those that flocculate on cooling are entropically stabilized.
Abstract: The incipient flocculation of sterically stabilized dispersions has been investigated. It was found that when a steric stabilizing barrier was supplemented by an electrostatic barrier, no change in the incipient flocculation point was evident at high ionic strengths. Dispersions sterically stabilized by commercial Pluronic nonionic surfactants, which are based on poly(ethylene oxide), exhibited incipient flocculation behavior similar to model dispersions stabilized by poly (ethylene) oxide. It is shown that dispersions which undergo flocculation on heating must be enthalpically stabilized, at least immediately below the incipient flocculation temperature; conversely, those that flocculate on cooling are entropically stabilized, at least just above the critical flocculation temperature (c.f.t.). Thus poly(ethylene oxide) is shown to function as an enthalpic stabilizer in water and as an entropic stabilizer in methanol. Experiments with strongly anchored steric stabilizers and multivalent cations demonstrate unequivocally the existence of the phenomenon of displacement flocculation at neutral pH. The order of flocculation effectiveness of cations (monovalent > divalent > trivalent) towards sterically stabilized dispersions is the reverse of that found in electrostatic stabilization, if displacement flocculation is absent. Displacement flocculation is promoted thermodynamically by weak anchoring, and by attractive electrostatic interactions between the particle surface and the displacing hydrolyzed species. It is retarded kinetically by increasing the molecular weight of the surf actant.
TL;DR: Nerve conduction studies were performed on the median, ulnar, and lateral popliteal nerves of 8 patients with Friedreich's ataxia, finding significant slowing of motor conduction, and impairment of sensory conduction.
TL;DR: In this paper, the variation of the zeta potential of oxides, as a function of electrolyte concentration, has been investigated using typical values of the double-layer parameters (e.g., thickness and dielectric constant of the compact region).
TL;DR: In this article, an asymptotic series solution for low Reynolds number flow through an axisymmetric tube whose radius varies slowly in the axial direction is obtained, and expressions for the pressure drop along the tube and the shear stress at the wall are derived.
Abstract: An asymptotic series solution is obtained for the low Reynolds number flow through an axisymmetric tube whose radius varies slowly in the axial direction. Expressions for the pressure drop along the tube and the shear stress at the wall are derived. The analysis is applicable to such problems as the flow through viscometric capillary tubes and the flow through blood vessels.
TL;DR: In this paper, it was shown that the paradox probability tends to unity as n ∞ for all m(m ≧ 3), however, this limit is seen to be attained very slowly when m is small.
Abstract: When a group of m individuals endeavours to choose a winner from a set of n alternatives by making all possible pairwise comparisons among the alternatives (using simple majority rule), there exists the possibility that no outright winner will emerge, e.g., a beats b, b beats c, c beats a. This phenomenon is called the paradox of voting, and it has been shown to have relevance in many contexts in the behavioural sciences.
In the first part of this paper, we prove the conjecture that the paradox probability tends to unity as n ∞ for all m(m ≧ 3): however, this limit is seen to be attained very slowly when m is small. We also note that the paradox probability is exactly doubled when the number of alternatives increases from 3 to 4, irrespective of the value of m. This work is restricted to the conventional case of an impartial culture, wherein all alternatives are intrinsically equally favoured.
In the second part, we give a simple yet accurate approximate formula for the paradox probability with n = 3 in a quite arbitrary culture, when the individual alternatives are not intrinsically equally favoured. The character of these results is discussed, and some specific examples are considered in detail.
TL;DR: In this article, a new description of anisotropic cohesive strength provides a simple solution for the bearing capacity of a strip load, based on previous work by Hill, and a survey of published data on shear strength indicate that bearing capacity at worst is 85% of what would be predicted using conventional Shear strength data for vertical compression and bearing capacity theory.
Abstract: A new description of anisotropic cohesive strength provides a simple solution for the bearing capacity of a strip load, based on previous work by Hill This solution and a survey of published data on anisotropic shear strength indicate that the bearing capacity at worst is 85% of what would be predicted using conventional shear strength data for vertical compression and bearing capacity theory The bearing capacity is 90% of that predicted by conventional theory and the average of strength from vertical and horizontal compression When compressive strength is available for three orientations of loading, the shear strength can be represented as an ellipse, and the bearing capacity depends on the shape of the ellipse and on the average of vertical and horizontal compressive strengths
TL;DR: Ventilatory response to CO 2 was measured regularly by a rebreathing technique in nineteen patients with severe asthma from the day of presentation to the time of clinical recovery, and increased during recovery in sixteen patients and correlated well with increase of FEVr.
Abstract: SUMMARY i. Ventilatory response to CO 2 was measured regularly by a rebreathing technique in nineteen patients with severe asthma from the day of presentation to the time of clinical recovery. 2. Ventilatory response to CO 2 increased during recovery in sixteen patients and the increased ventilatory response correlated well with increase ofFEVr- Amongthese sixteen patients only one showed elevation of arterial CO 2 tension at the time of presentation. 3. Ventilatory response to CO2 failed to increase during recovery in three patients despite increasesin FEVr- All three patients showed elevation of arterial CO 2 tension at the time. of presentation. 4. In five patients (including three of the four with initial hypercapnia) ventilatory response to CO2 after recovery remained below the previously reported lower limit for normal subjects. The limits of normality were explored by examining ventilatory response to CO 2 in seventeen outstanding athletic performers. Values for ventilatory response to CO 2 both above and below the previously defined 'normal range' were found. The normal ventilatory response to CO2 covers a 14-fold range from 0'57 to 8'171 min"" mmfIg"! Pco2 • It is well known that ventilatory response to inhaled CO 2 is impaired in patients with chronic obstructive airways disease. Less is known of the patterns of ventilatory response to CO 2 when the airways obstruction is both acute and reversible. Read (1967) developed a 4 min rebreathing test suitable for serial studies of ventilatory response to CO 2 in sick patients. In the present study this rebreathing method has been used to study ventilatory response to CO2 in patients recovering from attacks of severe asthma. Each patient was studied day by day during the course of clinical recovery so that, as airways obstruction lessened, each patient served as his own control. The range of ventilatory response to CO2 in normal subjects was also further explored.
TL;DR: Test dusks given to samples of flies which had been kept under a constant high light intensity showed that an endogenous rhythm of ‘readiness to mate’ persisted for two or possibly three cycles before damping out.
TL;DR: Depression of in vitro phytohemagglutinin-induced lymphocyte transformation was achieved by the addition of human chorionic gonadotropin (HCG) to the culture system in a concentration simulating the blood level attained during the greater part of pregnancy.
TL;DR: It is shown how the relative importance of changes in certain life-history features can change with r and be reversed when r is near to zero, the exponential rate of population increase.
Abstract: Previous authors have used simple models to investigate the relative importance to population increase of variations in the total and age-specific reproductive rates. But while acknowledging that the latter were the product of the age specific birth and death rates, they have used their models only to investigate changes in total or age-specific birth rates and have not been concerned with variations in death rates. This paper extends the use of Lewontin's (1965) model, to a wide range of values of r, the exponential rate of population increase. It shows how the relative importance of changes in certain life-history features can change with r and be reversed when r is near to zero. It is also shown that variations in mortality rate are not necessarily best expressed in analogous terms to variations in birth rate. If more suitable terms are used it is seen that changes in mortality rate can be of varying importance depending on the existing mortality rate. They can be overwhelmingly important when the mortality rate is high.
TL;DR: It is suggested that the abnormalities demonstrated in the inhibitory reflex in patients with temporomandibular dysfunction are due either to inadequate stimulation of dental pressoreceptors (due to premature contact or gross tooth loss) or to hyperactivity of the reticular formation associated with malalignment of the temporom andibular joint.
TL;DR: Renal amino acid transport mechanisms are of two kinds: the high-capacity low-specificity systems transport whole groups of amino acids—the acidic, basic, neutral, and imino-glycine groups—while the other, the low-capacity high- specificity systems, transport single or perhaps pairs of amino acid only.
Abstract: Cushny in 1917 first remarked on the extensive amino acid reabsorption which occurs in the nephron. Although many workers since then have studied the nature and localization of the reabsorptive mechanism, progress has been slow because of the technical difficulties of micropuncture work. The bulk of filtered amino nitrogen is reabsorbed in the proximal tubule although the possibility of there being more distal reabsorptive (or secretory) sites cannot be excluded. It is also uncertain whether all segments of the proximal tubule contribute equally to the reabsorptive process. Amino acid reabsorption is an active process involving numerous illdefined steps, the first of which is binding to the brush borders. Renal amino acid transport mechanisms are of two kinds: the high-capacity low-specificity systems transport whole groups of amino acids—the acidic, basic, neutral, and imino-glycine groups—while the other, the low-capacity high-specificity systems, transport single or perhaps pairs of amino acids only.
TL;DR: The evidence indicates that diazepam depresses the ventilatory response to CO2, and also modifies the characteristics of gas exchange within the lung, producing a rise in VD/VT, and often associated with a Rise in Pactco2.
Abstract: The effects of diazepam (0.14 mg/kg) on steady-state gas exchange were studied in 13 patients, and the responses to a carbon dioxide stimulus using a recently introduced rebreathing technique are described. There were significant increases in VD/VT and Paco2, and a decrease in VT. E and o2- were unc
TL;DR: In this article, it was predicted that vertical settings of a rod surrounded by a square frame would be in error in the direction of the frame axis closest to true vertical as the frame varied in tilt.
Abstract: It was predicted that vertical settings of a rod surrounded by a square frame would be in error in the direction of the frame axis closest to true vertical as the frame varied in tilt. Results were in accord with this hypothesis. The implications of the results are discussed.
TL;DR: The results suggest that both types of drug stimulate formation of an approximately plasma-like primary secretion whose composition changes only slightly with stimulation, and that parasympathomimetics cause production of 6–8 times more primary fluid per unit time than sympathomimetics.
Abstract: Salivary glands are generally supposed to produce their secretions in 2 stages: 1. A plasma-like secretion is formed in the acinar-intercalated duct region of the gland, the rate of production but not the electrolyte composition of this fluid being increased by gland stimulation. 2. This primary saliva is then modified during its passage along the gland duct system by processes of Na reabsorption and K and HCO3 secretion.
TL;DR: Some molecular parameters influencing rate of reduction of Azo compounds by intestinal microflora are discussed in this article, where the authors propose a method to identify the molecular parameters that influence the reduction rate of azo compounds.
Abstract: (1971). Some Molecular Parameters Influencing Rate of Reduction of Azo Compounds by Intestinal Microflora. Xenobiotica: Vol. 1, No. 4-5, pp. 483-486.
01 Nov 1971
TL;DR: In this paper, the repulsion energy was calculated using the constant charge assumption rather than that of constant potential, an observation which was in full accord with Frens' picture of the repeptization process.
Abstract: Rapidly coagulating colloidal suspensions exhibit plastic flow behavior so that energy in excess of the normal viscous energy is required to sustain flow. A theory is presented which correlates this excess energy with the interaction energy between the particles. The latter is calculated from the electrokinetic (ζ-) potential and the only arbitrary parameter required for a complete description is the distance of closest approach of the particles during a collision; the value of this parameter required for the calculation of the repulsive energy is, however, slightly different from that required for calculation of the attraction. It is found that the repulsion energy must be calculated using the constant charge assumption rather than that of constant potential an observation which is in full accord with Frens' picture of the repeptization process.
TL;DR: In this paper, the authors measured live-weight gain, diet digestibility, wool growth and the utilization of nitrogen and sulphur in cross-bred lambs, and found no significant effect of age on the apparent digestibility of the nutrients in diet B.
Abstract: I. Eighteen male cross-bred lambs, aged between z and 5 d, were allotted to two equal groups and given artificial milk diets of either low protein (diet A) or high protein (diet B) content for an experimental period of 6 weeks. Live-weight gain, diet digestibility, wool growth and the utilization of nitrogen and sulphur were measured. 2. There was a significant decrease with age in wool growth and in the apparent digestibility of dry matter, energy and N by lambs given diet A. There was no significant effect of age on the apparent digestibility of the nutrients in diet B. Live-weight gain and N balance were unaffected by age when expressed in relation to metabolic body size (kgo*7a).