Showing papers by "University of Sydney published in 1976"
TL;DR: In this article, the statistical properties of least-squares frequency analysis of unequally spaced data are examined and it is shown that the reduction in the sum of squares at a particular frequency is a X22 variable.
Abstract: The statistical properties of least-squares frequency analysis of unequally spaced data are examined. It is shown that, in the least-squares spectrum of gaussian noise, the reduction in the sum of squares at a particular frequency is aX22 variable. The reductions at different frequencies are not independent, as there is a correlation between the height of the spectrum at any two frequencies,f1 andf2, which is equal to the mean height of the spectrum due to a sinusoidal signal of frequencyf1, at the frequencyf2. These correlations reduce the distortion in the spectrum of a signal affected by noise. Some numerical illustrations of the properties of least-squares frequency spectra are also given.
4,950 citations
TL;DR: In this paper, the authors discuss the theoretical basis for diffusion flame analysis, with its implications on diffusion flame structure, and the limitations on the use of the two main reaction models, and address the question of the computation of the velocity and scalar fields focusing on the modeling of the turbulence under conditions of fluctuating and spatially varying density.
443 citations
TL;DR: From these structures a hypothetical liganded antibody molecule has been constructed, which is assumed to be rigid, while in the Fc fragment both CH3 and CH2 show the immunoglobulin fold.
Abstract: The crystal structures of a human IgG antibody molecule Kol and a human Fc fragment have been determined at 4-A and 3.4-A resolution respectively, by isomorphous replacement. The electron-density maps were interpreted in terms of immunoglobulin domains based on the Rei and McPC 603 models (Kol) and by model-building (Fc). The Fab parts of Kol have a different quaternary structure from that observed in isolated crystalline Fab fragments, there being no longitudinal V-C contact in Kol. The Fc part C terminal to the hinge is disordered in the Kol crystals. It is suggested that the Kol molecule is flexible in solution, whereas fragments are rigid. In the Fc fragment both CH3 and CH2 show the immunoglobulin fold. The CH3 dimer aggregates as CH1-CL while CH2 are widely separated from each other. The carbohydrate bound to Fc is in fixed position. From these structures a hypothetical liganded antibody molecule has been constructed, which is assumed to be rigid.
412 citations
TL;DR: The findings in this group of patients suggest that the common form of this syndrome is due to a single disease entity, and it is concluded that these diseases may constitute a spectrum of pathogenetically related disorders.
364 citations
TL;DR: In this article, the most effective discharge with regard to bed-load transport, the 1.58-year flood and the natural bankfull discharge are derived for Cumberland Basin streams.
336 citations
TL;DR: Abscisic acid and 2-chloroethyl phosphonic acid act synergistically with the sucrose to enhance its induction of both total phenolics and anthocyanin, and the magnitude of this interaction depends on leaf age.
Abstract: Sucrose (0.04 to 0.12 m) induces accumulation of both total phenolics and anthocyanin in leaf discs of grapevine (Vitis vinifera L.) incubated in intermittent light. Abscisic acid (20 μM) and 2-chloroethyl phosphonic acid (60 μm) act synergistically with the sucrose to enhance its induction of both total phenolics and anthocyanin. The magnitude of this interaction depends on leaf age. Nitrate (30 mm) inhibits sucrose induction of phenolics and anthocyanin. Levels of total phenolics and anthocyanin changed independently.
306 citations
TL;DR: In this article, a study on elephant-forest relationships in the Luangwa Valley of Zambia casts doubt upon the basic assumption of these hypotheses and an alternative hypothesis is therefore offered.
Abstract: Summary
Published hypotheses to account for habitat changes wrought by elephants begin from the assumption that elephant-forest systems possess a stable equilibrium point. The ‘elephant problem’ is conceived as a displacement of this equilibrium by man. Controversy centres around which human activities caused the dislocation of equilibrium and by which mechanisms these activities resulted in local high densities of the elephant Loxodonta africana. A study on elephant-forest relationships in the Luangwa Valley of Zambia casts doubt upon the basic assumption of these hypotheses and an alternative hypothesis is therefore offered. It begins from the opposite assumption–that there is no attainable natural equilibrium between elephants and forests in eastern and southern Africa. The relationship is viewed instead as a stable limit cycle in which elephants increase while thinning the forest and decline until reaching a low density that allows resurgence of the forest. This in turn triggers an increase of elephants and the cycle repeats. The period of the cycle, if the hypothesis is correct, is in the order of 200 years in the Luangwa Valley.
The activities of man can impose an artificial equilibrium on the system such that trees and elephants are trapped at the low density phase of the cycle. When interference is relaxed, as with the conversion of an area to a national park, the cyclic relationship reasserts.
The parameters of a system possessing a stable limit cycle need not differ in kind or interrelationship from those of a system with a stable equilibrium. Whether one or other outcome manifests may depend only on the numerical values of the parameters. If the elephant-forest system is characterized by a stable limit cycle the period and amplitude should change along a climatic gradient and may contract to a stable equilibrium in some climatic zones. A set of predictions is offered to facilitate rejection of the hypothesis.
305 citations
264 citations
TL;DR: In this article, the viscous flow behavior of a colloidal sol can be described in terms of the various contributions to the energy dissipation during flow, and a satisfactory description of the known features of the basic shear diagram can be obtained by attributing most of the dissipation to two processes: (i) viscous flows of the suspension medium around the flocs, which are the basic flow units, and (ii) the energy involved in stretching the flos in order to break floc doublets apart so that the amount of structure in the system is
192 citations
01 Nov 1976
TL;DR: In this article, the flow properties of electrically charged, but unstable, colloidal sols are investigated in the light of three possible models, i.e., hard (nondeformable) floc, elastic floc and hard (non-nondefinite) particle model, and they are shown to provide a consistent physical interpretation of both the linear region of the flow curve and the Bingham yield value.
Abstract: The flow properties of electrically charged, but unstable, colloidal sols are investigated in the light of three possible models. Models which treat the ultimate flow unit at high shear rate as either a single particle or a hard (nondeformable) floc are shown to be incapable of providing a satisfactory description of the behavior. On the other hand an elastic floc model provides a consistent physical interpretation of both the linear region of the flow curve and the Bingham yield value for these plastic-pseudoplastic systems.
187 citations
TL;DR: In this paper, the molarities of the salts required to precipitate the maximum amounts of Fe, Al and humates decrease in the order: NaCl, MgCl2, CaCl2.
TL;DR: In this article, two thin sand beds were intercalated between beds of cohesive material, acting as knickpoint-forming horizons on which stepped knickpoints were developed and maintained as they moved upstream.
Abstract: In a flume study of knickpoint development in stratified sediment, two thin sand beds were intercalated between beds of cohesive material. The sand beds acted as knickpoint-forming horizons on which stepped knickpoints were developed and maintained as they moved upstream, creating an apparently stable form consisting of a channel-in-channel system. The system had four basic elements: (1) an aggraded reach upstream of the knickpoint, terminating on the downstream end at a fill-incision transition zone; (2) an oversteepened reach just above the knickpoint face; (3) the knickpoint face; and (4) an incising reach, often covered by moving sediment between successive knickpoints.
Apparently the presence of a knickpoint-forming horizon reduces knickpoint retreat rates, which were much lower in this study than those observed in an experiment with cohesive material but no intercalated sand beds and a similar discharge. Also, the channel-in-channel system that results from stratification is apparently fairly insensitive to the effects of changing discharge.
TL;DR: Genotypic frequencies were analysed for two years in a permanent population of the cladoceran crustacean, Daphnia magna, which was polymorphic for an esterase and for malate dehydrogenase, and non-random associations between genotypes at structural and regulatory loci showed temporal changes.
Abstract: Genotypic frequencies were analysed for two years in a permanent population of the cladoceran crustacean, Daphnia magna, which was polymorphic for an esterase and for malate dehydrogenase. Large temporal changes in genotypic frequencies occurred at both loci. There was no evidence of a seasonal pattern in the frequency changes. In most samples, genotypes at the two enzyme loci were non-randomly associated; these associations showed temporal changes. On some occasions marked spatial heterogeneity in genotypic frequencies existed within the population. Genotypic differences in parthenogenetic and sexual egg production were observed. In a primarily parthenogenetically reproducing population, non-random associations between genotypes at structural and regulatory loci will be the rule. The allozyme variants themselves may or may not be under selection. The relevance of these observations to ecological studies on Daphnia is considered.
TL;DR: In this paper, the relationship between the experimental flow parameters and the colloidal parameters (volume fraction, particle size, and interactive forces) is examined and ten such relationships can be used to test the validity of possible models of the flow of coagulated suspensions.
TL;DR: In this article, a theory of the behavior of an ideal mass of two-phase soil is developed, which unifies the usually separately considered aspects of analytical soil mechanics of settlement and deformation; time dependent consolidation; and yielding leading to collapse of the mass.
TL;DR: It is suggested that a subacute onset of the illness, electromyographic evidence of denervation or gross slowing of conduction, and significant reduction of numbers of myelinated fibres or onion-bulb formation on sural nerve biopsy are factors which may indicate a prolonged course of the illnesses or incomplete recovery.
TL;DR: In this paper, the discovery of buried corals at two localities on the E coast of Australia has provided an opportunity to determine more precise ages by 230Th/234U dating.
Abstract: 230Th/234U dating of coral terraces at 2–9 m above sea level on ‘stable’ oceanic islands has suggested that the sea level during the last interglacial, 120,000–140,000 yr BP (refs 1–3) was slightly higher than at present. However, accurate dating of interglacial shoreline facies on continental coasts far removed from plate boundaries has been largely neglected (the west coast of Australia1 and Florida4 are exceptions). Attempts have been made to date interglacial shoreline deposits from SE Australia using molluscs5, but this has proved unreliable6. The recent discovery of buried corals at two localities on the E coast of Australia has provided an opportunity to determine more precise ages by 230Th/234U dating.
TL;DR: Results of quantitative studies performed on the dorsal root ganglia and spinal cord of Trembler mice did not differ from those in controls, and the density of myelinated fibres was reduced at all ages when compared with controls.
TL;DR: Intraspecific competition for food within and between age-classes of the intertidal grazing gastropod Nerita atramentosa Reeve was investigated using experimental cages on a rock platform in Botany Bay, New South Wales, finding population density regulation in Nerita is possible.
TL;DR: Most Drosophila species show a relatively uniform spatial pattern of gene frequencies, even across wide climatic distributions, which could be due to the unifying force of migration opposing differential selection in different populations, or to similar selective forces throughout the distribution.
Abstract: Since the first demonstration that natural populations of Drosophila are polymorphic for a high proportion of protein and enzyme loci (Hubby and Lewontin, 1966; Lewontin and Hubby, 1966; Johnson et al., 1966), similar high levels of electrophoretically detectable genetic variation have been found for many species (e.g., Johnson, 1974; Lewontin, 1974; Selander and Johnson, 1973). The mechanisms by which this variation is maintained within populations and transformed into variation between populations remain uncertain. Recent experimental studies of natural populations have concentrated on the question as to whether the variation is maintained through some form of selection or whether it is selectively neutral. Some form of selection would be indicated, although not necessarily for the marker isozyme locus, if the frequency of a particular allele were found to vary consistently with change in some environmental component. Thus a number of attempts have been made to detect such associations (e.g., Johnson and Schaffer, 1973; Kojima et al., 1972; Rockwood-Sluss et al., 1973; Tomaszewski et al., 1973) or associations between heterozygosity and environmental variability (Bryant, 1974a,b). However, most Drosophila species show a relatively uniform spatial pattern of gene frequencies, even across wide climatic distributions. This uniformity could be due to the unifying force of migration opposing differential selection in different populations, or to similar selective forces throughout the distribution, i.e. a function of the physiological properties of the molecules,
TL;DR: Observations suggest that P. foliaceum contains a membrane‐bound endosymbiont, similar to that already described for the closely related species P. balticum (Levander) Lemmermann.
Abstract: SUMMARY
The fine structure of the binucleate, fucoxanthin-containing dinoflagellate Peridinium foliaceum (Stein) Biechler was re-examined for evidence of an endosymbiout. The eucaryotic nucleus, chloroplasts and associated ribosome-dense cytoplasm were separated by a single invaginating membrane from the rest of the dinoflagellate cell. The triple membrane-enclosed eyespot, mesocaryotic nucleus, trichocysts and accumulation bodies resided in the dinoflagellate cytoplasm. These observations suggest that P. foliaceum contains a membrane-bound endosymbiont, similar to that already described for the closely related species. P. balticum (Levander) Lemmermann.
TL;DR: It is suggested that displacement is essentially non-competitive and that glibenclamide is less susceptible to displacement by acidic drugs than tolbutamide or chlorpropamide.
TL;DR: Thin-layer chromatography showed that chlorophyll b was present in acetone extracts of 6 samples of suspended matter collected in February 1973 from the Central North Pacific Ocean.
Abstract: Thin-layer chromatography showed that chlorophyll b was present in acetone extracts of 6 samples of suspended matter collected in February 1973 from the Central North Pacific Ocean. Pigment patterns showed the presence of green algae and diatoms through most of the euphotic zone down to 200 m. Ratios of chlorophyll b:a ranged from 0.2 to 0.5 at 5 and 100 m depths, but were less than 0.05 at 200 m.
TL;DR: In this paper, a computational method based on a rapidly convergent form of the unlinked cluster expansion is presented, where Ciźek's coupled-pair approximation is derived in a basis of partially non-orthogonal orbitals which transform each pair function to diagonal form; this produces a simple (non-variational) set of equations from which may be extracted the energy and coefficients of a wavefunction constructed from the Hartree-Fock function, all double excitations and all unlinked clusters of these.
TL;DR: The Melanesian Borderlands as discussed by the authors is a complex of seven subdivisions, most of which are Cainozoic tectonic unities, including the Bismarck Sea and surrounding, Solomon Block, Coral Sea and eastern extension, New Hebrides and South Fiji Basins, South Fiji Basin and Lau Basin, Fiji Platform, Lau and Tonga Ridges.
TL;DR: In this article, the mixing of 2% sulphaphenazole (mean diameter 25 μm) with coarse directly compressible tablet vehicles has been studied using a sampling method and scanning electron microscopy.
TL;DR: It is suggested that clinical doses of verapamil cause peripheral vasodilation which leads to a sympathetic reflex induced increase in heart rate and myocardial contractility and this effect was partly mediated through cholinergic stimulation and partly through a direct depression on atrioventricular conduction.
Abstract: Verapamil (Isoptin®) caused a dose-dependent peripheral vasodilation, increase in myocardial contractility, and tachycardia in the anaesthetized dog. Propranolol pre-treatment blocked the cardiac stimulation following verapamil but the vasodilation was unaltered. Inflation of a thoracic aortic balloon prevented the fall in intravascular pressure and reduced the tachycardia and positive inotropic responses. These experiments suggest that clinical doses of verapamil cause peripheral vasodilation which leads to a sympathetic reflex induced increase in heart rate and myocardial contractility. Verapamil also had a direct myocardial depressant action which became evident at doses above the range used clinically. The drug increased the PR interval in conscious dogs for up to 60 minutes. This effect was partly mediated through cholinergic stimulation and partly through a direct depression on atrioventricular conduction.
TL;DR: In this article, the probability density functions of temperature in the intermittent regions of heated jet and wake flows show a strong spike associated with the temperature of the unheated fluid, and the fine structure of this spike fits a Gaussian curve quite closely.
Abstract: The probability density functions of temperature in the intermittent regions of heated jet and wake flows show a strong spike associated with the temperature of the unheated fluid. The fine structure of this spike fits a Gaussian curve quite closely, and the area under this Gaussian gives an accurate measure of 1−γ where γ is the intermittency factor. The standard deviation of the Gaussian is a measure of the noise due to residual temperature fluctuations in the free‐stream and the electronic noise in the measurement system. The accuracy with which the intermittency can be determined is limited by the signal‐to‐noise ratio.
TL;DR: Recruitment of juvenile P. wardi, and survival of experimentally added juvenile P.'s wardi were both greater in patches from which all adult pomacentrids had been removed than in patches with undisturbed adult populations, according to an experiment on patches of rubble on reefs of the Great Barrier Reef.
TL;DR: Certain impressive epidemiological evidence appearing in the last few years leads to the conclusion that some males are more prone to have a spouse with squamous cancer of the cervix than others.