Showing papers by "Australian National University published in 1972"
TL;DR: In this paper, the partition function of the zero-field eight-vertices model on a square M by N lattice is calculated exactly in the limit of M, N large.
1,648 citations
TL;DR: In this paper, a set of coupled-mode equations is derived to describe mode propagation in uniform and slightly nonuniform cylindrical optical-fiber systems, and the coupling between fibers of an array made up of n identical fibers each at the vertex of a polygon and one at the center, which is not necessarily the same as its n neighbors, is determined.
Abstract: A set of coupled-mode equations is derived to describe mode propagation in uniform and slightly nonuniform cylindrical optical-fiber systems. The coupling between fibers of an array made up of n identical fibers each at the vertex of a polygon and one at the center, which is not necessarily the same as its n neighbors, is determined. Examples of this array are two fibers, three fibers in a row, and a hexagonal array with a fiber in the center. Very simple expressions for the coupling coefficients are presented. Mode coupling on a lossy fiber is investigated and a simple expression for the loss of a HE11 mode is given.
695 citations
TL;DR: The high affinity uptake system for l‐glutamate and l‐ aspartate in rat cerebral cortex may not be specific for these likely excitatory synaptic transmitters, as threo‐3‐hydroxy‐dl‐aspartate, l‐cysteinesulphinate, l-cysteate and d‐as partate strongly inhibit the observed high affinity take-up by rat brain slices in a manner consistent with linear competitive inhibition.
Abstract: — The high affinity uptake system for l-glutamate and l-aspartate in rat cerebral cortex may not be specific for these likely excitatory synaptic transmitters, as threo-3-hydroxy-dl-aspartate, l-cysteinesulphinate, l-cysteate and d-aspartate strongly inhibit the observed high affinity uptake of l-[3H]glutamate by rat brain slices in a manner consistent with linear competitive inhibition. These substances should therefore be considered as possible substrates for the transport system. Each of these four acidic amino acids excites central neurones in a manner similar to excitation induced by l-glutamate, and as each might occur in brain tissue, their possible synaptic role should be investigated.
l-Glutamate high affinity uptake was shown to be sodium-dependent, but under certain conditions appeared to be less sensitive than GABA uptake to changes in the external sodium ion concentration, and to drugs which modify sodium ion movements. This may be relevant to the efficiency of the glutamate uptake process during synaptic depolarization induced by glutamate.
l-Glutamate high affinity uptake was inhibited in a relatively nonspecific manner by a variety of drugs including mercurials and some electron transport inhibitors.
690 citations
TL;DR: In this paper, the composition of island-arc volcanic rocks in relation to their geographic and stratigraphic relations is discussed and the differences in composition between volcanic rocks and those in continental margins are pointed out.
Abstract: The composition of recent island-arc volcanic rocks in relation to their geographic and stratigraphic relations is discussed. The differences in composition between volcanic rocks and those in continental margins are pointed out. Trace elements and major elements are shown to suggest a continuous gradational sequence from tholeiites through calc-alkaline rocks to shoshonites.
463 citations
TL;DR: Haploid callus cultures of selected races of Lycopersicon (tomato) species can be obtained from anther culture as a further demonstration of a proposed general method of haploid culture developed with Arabidopsis thaliana.
Abstract: Haploid callus cultures of selected races of Lycopersicon (tomato) species can be obtained from anther culture. This is a further demonstration of a proposed general method of haploid culture developed with Arabidopsis thaliana. Differentiation of haploid callus of Lycopersicon esculentum can be controlled both in the dark and the light by hormones added to defined minimal media. Development to plantlets is achieved only in the light. Callus cells can be induced to develop into seedless pseudo-fruits. Chromosome counts on callus cells or root-tip cells establishes haploidy (n=12).
458 citations
TL;DR: It is demonstrated that a homogeneous lens is not satisfactory for modelling a small eye and a core lens model is provided and a new one is developed.
421 citations
TL;DR: The minimum eigenvalue of the Hamiltonian of an infinitely long one-dimensional anisotropic Heisenberg chain is evaluated in this paper, where the minimum eigensmidth of the chain is also investigated.
354 citations
TL;DR: A technique is described for fitting a sharpened tungsten wire and a glass micropipette together so that a precisely controlled amount of bare wire is exposed at the tip.
Abstract: A technique is described for fitting a sharpened tungsten wire and a glass micropipette together so that a precisely controlled amount of bare wire is exposed at the tip. The method is tedious and demanding but produces very reliable electrodes yielding isolated extracellular recordings from single nerve cells and their axons.
353 citations
TL;DR: Interaction of pH optima and NaCl concentrations suggests that enzymes may differ in the way they respond to salt treatment, and indicates that plants grown in saline cultures showed no important changes in specific activity or salt sensitivity.
Abstract: Enzymes which are affected by the addition of inorganic salts during in vitro assay were extracted from salt-sensitive Phaseolus vulgaris, salt-tolerant Atriplex spongiosa, and Salicornia australis and tested for sensitivity to NaCl. In each case malate dehydrogenase, aspartate transaminase, glucose 6-phosphate dehydrogenase, and isocitrate dehydrogenase showed NaCl responses similar to those found for commercially available crystalline enzymes from other organisms. Enzymes extracted from plants grown in saline cultures showed no important changes in specific activity or salt sensitivity. Interaction of pH optima and NaCl concentrations suggests that enzymes may differ in the way they respond to salt treatment.
308 citations
TL;DR: The semantics of entailment in modal logics have been studied in this paper, where a ternary relation R is proposed to take the place for the relevant logics of the Kripke binary relation for standard modal and intuitionistic logics.
Abstract: Publisher Summary This chapter discusses the semantics of entailment. Earlier, modal logics had no semantics. Bearing a real world G, a set of worlds K, and a relation R of relative possibility between worlds, Saul Kripke beheld this situation and saw that it was formally explicable and made model structures. It came to pass that soon everyone was making model structures, and some were deontic, some were temporal, and some were epistemic, according to the conditions on the binary relation R. The models made by Kripke, Hintikka, and Thomason were, however, not relevant. Central to the semantics being developed is a ternary relation R that takes the place for the relevant logics of the Kripke binary relation for standard modal and intuitionistic logics.
274 citations
TL;DR: In this article, the authors used a dilatometric method to measure volume changes during straining to 20 per cent at confining pressures up to 8 kb, as well as during application and release of the pressure, in lithographic limestone, Carrara marble, sandstone, talc, graphite and sodium chloride.
TL;DR: The depolarization of motoneurones by dl -homocysteate was not altered by changes in intracellular chloride concentration, or extracellular concentrations of tetrodotoxin sufficient to suppress spike generation, and the action of the amino acid thus probably resembles that of synaptically released excitatory transmitters.
TL;DR: This review will attempt to throw some light on the factors which modulate humoral and cell-mediated immunity in vivo, and in particular, to present compelling evidence that in many situations theHumoral and cellular responses are mutually antagonistic.
Abstract: It has been known for many years that when an antigen is injected into an animal, both humoral and cell-mediated immunity can be induced. However, different antigens show a remarkable variation in their capacity to induce these two immune responses. For example, some antigens appear to be predisposed to induce antibody formation, whilst other antigens predominantly provoke delayed-type hypersensitivity (Turk 1967). Furthermore, the route and mode of injection of any one antigen can have a profound effect on the type of immune response which occurs (Pappenheimer & Freund 1959). The biological factors which determine whether humoral or cell-mediated immunity predominates are not well understood, although it has been tentatively proposed that delayed-type hypersensitivity is induced by antigens which are only partially recognized as 'foreign' by the responding animal (Pearson & Raffel 1971). This review will attempt to throw some light on the factors which modulate humoral and cell-mediated immunity in vivo, and in particular, to present compelling evidence that in many situations the humoral and cellular responses are mutually antagonistic.
TL;DR: Theoretical results based on the methods of Freeman and Garr & Marrone show that the stand-off distance and flow pattern of non-equilibrium dissociating flow of nitrogen over the front part of a blunt body can be correlated in terms of a single reaction rate parameter ω taking account of parameters describing the speed, density, dissociation and temperature of the free stream as discussed by the authors.
Abstract: Theoretical results based on the methods of Freeman and Garr & Marrone show that the stand-off distance and flow pattern of non-equilibrium dissociating flow of nitrogen over the front part of a blunt body can be correlated in terms of a single reaction rate parameter ω taking account of parameters describing the speed, density, dissociation and temperature of the free stream. The density pattern, which is sensitive to the reaction rate, consists of two distinct regions dominated by the effects of reaction and pressure respectively. The shape and size of these regions depend on Q. Experimental results obtained by optical interferometry in a free-piston shock tunnel confirm the theoretical results. A scale effect consistent with the induction time phenomenon suggested by Shui, Appleton & Keck modifies the theoretical results considerably in the case of small models.
TL;DR: Data presented in this paper reveal that both high and low zone antibody tolerance to flagellin were associated with heightened levels of delayed-type hypersensitivity, and an inverse relationship appears to exist between humoral and cell-mediated immunity.
Abstract: Recent studies in this laboratory have indicated that humoral and cell-mediated immunity may be intimately related (1-3). Using a series of acetoacetylated derivatives of flagellin, it was observed that increasing acetoacetylation steadily destroyed the ability of flagellin to initiate antibody formation but enhanced the capacity of the molecule to induce flagellin-specific delayed-type hypersensitivity and antibody tolerance. Thus, in this system antibody tolerance in adult rats was accompanied by enhanced cell-mediated immunity. If this relationship represents a general phenomenon, then it would be predicted that all states of antibody tolerance in adult animals should be accompanied by enhanced cell-mediated immunity. Using bacterial flagellin as the antigen, studies were initiated to test this prediction. It has been previously reported that antibody tolerance to flagellin can be induced in adult rats by multiple injections of a cyanogen bromide (CNBr) digest of flagellin at two widely spaced dose levels (4). This phenomenon is called high and low zone antibody tolerance (5). Intermediate doses of the CNBr digest resulted in very high antibody titers rather than in antibody tolerance. Data presented in this paper reveal that, as predicted, both high and low zone antibody tolerance to flagellin were associated with heightened levels of delayed-type hypersensitivity . Furthermore, when enhancement of the antibody response occurred, suppression of delayed-type hypersensitivity was observed. Thus, an inverse relationship appears to exist between humoral and cell-mediated immunity. However, this relationship is not invariably true as rats from another strain exhibited only a partial inverse relationship. In addition, it was confirmed (3) that administration of antigen to neonatal rats induced tolerance at the level of both humoral a nd cell-mediated immunity.
TL;DR: The stability of concanavalin A is investigated in a wide range of environments by optical rotation, sedimentation and turbidity measurements and in terms of environments suitable for carbohydrate binding studies.
TL;DR: In this article, the authors examined the scattering hypothesis in more detail and presented evidence in its favour, concluding that precursors are the result of scattering of PKP waves from irregularities in the vicinity of the core-mantle boundary.
Abstract: THE so-called precursors to PKP consist of a train of arrivals preceding the core phase PKIKP, of small but variable amplitude, and commonly observed in the distance range 125° to 143°. Interpretations of this phenomenon have included dispersion near the boundary of the inner core1,2, diffraction from the PKP caustic3, sharp upward refraction within one or more transition layers surrounding the inner core4–6 and reflexions from small discontinuities at the boundaries of such transition layers7,8. In order to take account of certain unexplained features of the observations, Haddon9 recently advanced the alternative hypothesis that precursors are the result of scattering of PKP waves from irregularities in the vicinity of the core-mantle boundary. We examine the scattering hypothesis in more detail, and present evidence in its favour.
TL;DR: The theory that iron, taken up by the cell as ferric-enterochelin is only available for general cell metabolism after hydrolysis of the ligand by enterochelin esterase is supported.
Abstract: Three mutant strains of Escherichia coli have been isolated which are lacking ferric-enterochelin esterase activity. This enzyme catalyzes the hydrolysis of the enterochelin moiety of ferric-enterochelin to yield ultimately three molecules of N-2,3-dihydroxybenzoylserine. The mutants (designated fes−) were shown to be unaffected in enterochelin biosynthesis, capable of enterochelin-mediated iron uptake, and able to utilize ferric-dihydroxybenzoylserine complexes normally. When grown under iron-deficient conditions, however, they showed an absolute requirement for added iron or citrate, a phenotype characteristic of mutants defective in some part of the enterochelin system of iron uptake. These results support the theory that iron, taken up by the cell as ferric-enterochelin is only available for general cell metabolism after hydrolysis of the ligand by enterochelin esterase. The three fes− strains were shown to be affected in the B component of enterochelin esterase. The fesB gene which is probably the structural gene coding for component B of the esterase, was shown to be located at about minute 14 on the E. coli chromosome together with seven other genes involved in the enterochelin system of iron transport.
TL;DR: Cats require a normal, binocular visual environment during development to achieve the proper interocular alignment, and it is hypothesized that during normal development, the binocular patterned visual input stimulates some part of the cat's visual system to align the eyes properly.
TL;DR: A model of the mechanism causing sustained oscillations, in stomatal conductance, in a cotton plant exhibiting sustained oscillatory behaviour is developed and is shown to have many of the characteristics of free-running oscillations in real plants.
Abstract: Measurements of transpiration, leaf water content, and flux of water in a cotton plant exhibiting sustained oscillations, in stomatal conductance are presented, and a model of the mechanism causing this behaviour is developed. The dynamic elements, of the model are capacitors—representing the change of water content with water potential in mesophyll, subsidiary and guard cells—interconnected by resistances representing flow paths in the plant. Increase of water potential in guard cells causes an increase in stomatal conductance. Increase of water potential in the subsidiary cells has the opposite effect and provides the positive feed-back which can cause stomatal conductance to oscillate. The oscillations are shown to have many of the characteristics of free-running oscillations in real plants. The behaviour of the model has been examined, using an analogue computer, with constraints and perturbations representing some of those which could be applied to real plants in physiological experiments. Aspects of behaviour which have been simulated are (a) opening and closing of stomata under the influence of changes in illumination, (b) transient responses due to step changes in potential transpiration, root permeability and potential of water surrounding the roots, (c) the influence of these factors on the occurrence and shape of spontaneous oscillations, and (d) modulation of sustained oscillations due to a circadian rhythm in the permeability of roots.
TL;DR: In this article, it was shown that phase transformations play a major role in driving the lithosphere slab into the mantle at depths greater than 300 km, and also control the stress distribution within the slab.
TL;DR: An electron microscope study of the mode of lymphocyte migration across the endothelial layer of venules in the Peyer's patches of mice and rats concluded that lymphocytes migrate across the vascular endothelium by insinuating themselves between endothelial cells and not by passing through them.
Abstract: An electron microscope study was made of the mode of lymphocyte migration across the endothelial layer of venules in the Peyer's patches of mice and rats. Single and serial sections were examined. Of a total of about 800 lymphocytes observed in single sections, 91% were located between endothelial cells and 9% were surrounded by endothelial cytoplasm in the particular plane of section. 62% of the lymphocytes occurred in groups of two or more. In long sequences of serial sections through 21 endothelial cells, all lymphocytes were located external to the endothelial cells though some appeared "internal" at certain levels of sectioning. The probability that a lymphocyte which appears to be surrounded by endothelial cell cytoplasm actually lies within the cell was analyzed with a mathematical model derived from data obtained from single sections. The results of this analysis suggested that at least 93–99% of lymphocytes (within 90% limits of confidence) take an intercellular path in their migration from blood to lymph. It is concluded that lymphocytes migrate across the vascular endothelium by insinuating themselves between endothelial cells and not by passing through them. Rather than constituting an increased barrier to cell migration, the unusual height of the endothelial cells in these vessels is interpreted to be a special adaptation which allows sustained cell traffic without excessive fluid loss taking place concomitantly.
TL;DR: A series of radiocarbon determinations have been carried out of lacustrine deposits contained in three playa basins, namely at Sambhar, Didwana and Lunkaransar, in Rajasthan, in conjunction with stratigraphical and palynological investigations.
TL;DR: In this paper, it was shown how martingale theorems can be used to widen the scope of classical inferential results concerning autocorrelations in time series analysis.
Abstract: In this paper it is shown how martingale theorems can be used to appreciably widen the scope of classical inferential results concerning autocorrelations in time series analysis. The object of study is a process which is basically the second-order stationary purely non-deterministic process and contains, in particular, the mixed autoregressive and moving average process. We obtain a strong law and a central limit theorem for the autocorrelations of this process under very general conditions. These results show in particular that, subject to mild regularity conditions, the classical theory of inference for the process in question goes through if the best linear predictor is the best predictor (both in the least squares sense).
01 Jan 1972
TL;DR: The Apollo 12 basalts as mentioned in this paper provide clear evidence for the genesis of olivine-rich basalts in the lunar interior, and the nature of the source rock is deduced to be pyroxenite or olivinesbearing pyroxensite in which orthopyroxene is probably the major phase with lesser sub-calcic or pigeonitic clinopyroxenes.
Abstract: Experimental studies at 1 bar and up to 30 kbar establish the crystallization sequences for basalts 12021, 12065, 12022, 12009 and 12040. Olivine is the liquidus phase at low pressures, with minor chromium spinel and pigeonitic clinopyroxene joining the olivine at lower temperatures or accompanying the olivine in the less magnesian basalts (12021, 12065). At higher pressures, subcalcic clinopyroxene becomes the liquidus phase except in the most magnesian basalt (12040) where orthopyroxene joins the olivine and becomes the liquidus phase at pressures of 25 kbar. Integration of experimental studies with observed mineralogy of natural rocks shows conclusively that the basalt compositions studied do not lie on a plagioclase + pyroxene + spinel ± olivine cotectic nor have these rocks been derived by accumulation of olivine or pyroxene into such a low temperature cotectic liquid. The Apollo 12 basalts provide clear evidence for the genesis of olivine-rich basalts in the lunar interior. The nature of the source rock is deduced to be pyroxenite or olivine-bearing pyroxenite in which orthopyroxene is probably the major phase with lesser sub-calcic or pigeonitic clinopyroxene. The 100 Mg/(Mg+Fe) ratio of the source region in the deep lunar interior is 75–80.
TL;DR: It is concluded that uptake of L-glutamate is independent of both the tetrodotoxin-insensitive depolarization and the tetrocarbon-sensitive sodium ion influx induced by L- glutamate.
Abstract: Uptake of L-glutamate into rat brain slices from media containing either 10−3 or 10−8 M labelled L-glutamate is not inhibited by (a) excitant amino acids which have an appreciably greater depolarizing action on central neurones than that of L-glutamate, (b) antagonists of L-glutamate induced excitation of central neurones, or (c) tetrodotoxin in concentrations which inhibit the sodium ion influx into brain slices produced by L-glutamate and other excitant amino acids.
It is concluded that uptake of L-glutamate is independent of both the tetrodotoxin-insensitive depolarization and the tetrodotoxin-sensitive sodium ion influx induced by L-glutamate.
TL;DR: Evidence from adult thymectomized mice indicated that T cells which had left the thymus more than 6 weeks or less than 3 weeks prior to immunization could act as progenitors of effector T cells, and that no cooperaiion between these 2 cell classes was necessary for an optimal response.
Abstract: Four lines of evidence indicated that thymus-derived (T) cells play an essential role in the expression of cell-mediated immunity (CMI) to Listeria. a) T cell depleted (ATx-BM) CBA mice were unable to generate antibacterial immunity. b) Responsiveness was restored to ATx-BM CBA mice by injection of CBA X C57BL F1 thymocytes and essential CMI effector cells were derived from the F1 thymocytes (identified by anti-H-2 sera). c) The activity of immune cells from intact CBA mice was abolished by anti-theta treatment but d) enriched by treatment with anti-B cell, anti-macrophage serum. Evidence from adult thymectomized mice and that described in b) above, indicated that T cells which had left the thymus more than 6 weeks or less than 3 weeks prior to immunization could act as progenitors of effector T cells, and that no cooperaiion between these 2 cell classes was necessary for an optimal response.
TL;DR: Brevianamide-C and -D are shown to contain a 2′-indoxylidenealkane chromophore and are the stereoisomers (1 ) and (2 ) respectively.