Showing papers by "Australian National University published in 1969"
TL;DR: In this article, the problem of estimating the components of a mixture of two normal distributions, multivariate or otherwise, with common but unknown covariance matrices is examined, and the maximum likelihood equations are shown to be not unduly laborious to solve and the sampling properties of the resulting estimates are investigated.
Abstract: SUMMARY The problem of estimating the components of a mixture of two normal distributions, multivariate or otherwise, with common but unknown covariance matrices is examined. The maximum likelihood equations are shown to be not unduly laborious to solve and the sampling properties of the resulting estimates are investigated, mainly by simulation. Moment estimators, minimum x2 and Bayes estimators are discussed but they appear greatly inferior to maximum likelihood except in the univariate case, the inferiority lying either in the sampling properties of the estimates or in the complexity of the computation. The wider problems obtained by allowing the components in the mixture to have different covariance matrices, or by having more than two components in the mixture, are briefly discussed, as is the relevance of this problem to cluster analysis.
813 citations
TL;DR: A general rate equation has been derived and shown to be quadratic with square and linear terms in v which represents that true initial steady-state velocity of enzymic reactions that are reversibly inhibited by a substrate analogue at concentrations comparable to that of the enzyme.
773 citations
TL;DR: The BEL (A0) strain of influenza virus was disrupted with sodium dodecyl sulphate (SDS), and the hemagglutinin subunits were isolated by electrophoresis on cellulose acetate strips, suggesting that the “spikes” seen on the surface of influenzairus particles are of two morphologically distinct kinds.
302 citations
TL;DR: A hydroxamic acid (aerobactin) is excreted by cultures of Aerobacter aerogenes 62-1 and related strains when growing in an iron-deficient medium.
295 citations
TL;DR: The changes in blood-pressure were significantly correlated with the changes in catecholamine output in the thirty-seven subjects studied and labile hypertensive patients show on the average a heightened sympathetic response to mental stress.
213 citations
209 citations
TL;DR: The ability of antigen-reactive cells to react with antigen was immunologically significant and they were distinguished from cells present because of a prior experience of the animal with a related antigen.
Abstract: A QUESTION of current interest is whether the initial stages of an immune response—either the induction of antibody formation or of specific tolerance—may involve the reaction of an antigen with a specific lymphocyte. Naor and Sulitzeanu1 have demonstrated, both in vivo and in vitro, a reaction of 125I-labelled bovine serum albumin with a small proportion (about 1/5,000) of mouse spleen lymphocytes. We have since shown2 that both flagellin and polymerized flagellin (Salmonella adelaide) and haemocyanin (Jasus lalandii) labelled with 125I or 131I react in vitro with certain cells from spleens of rats and mice. Of the strongly reactive cells, almost all are mononuclear with a high nuclear/cytoplasmic ratio and 7–12 microns in diameter and, for any one antigen, comprise about 1/5,000 of the total cell population. These reactive cells adsorb between 4,000–40,000 molecules of labelled protein when allowed to react at 0° C with labelled protein (about 3 × 1012 molecules/ml.) in 10 per cent foetal calf serum. A similar proportion of such reactive cells was observed in cell suspensions from lymph nodes and thoracic duct lymph, while peritoneal exudate contained a higher proportion and thymus a lower proportion of these cells2. The reaction was not inhibited by concentrations of sodium azide which restricted the uptake of labelled antigen by macrophages but was inhibited, using mouse cells, by rabbit anti-mouse globulin serum. Spleen cells from germ-free and conventional mice reacted equally well with 131I-labelled flagellin2. We wished to know whether the ability of these cells to react with antigen was immunologically significant. Experiments were devised to distinguish between the following possibilities: that the reactive cells were (1) cells present because of a prior experience of the animal with a related antigen, (2) antigen-reactive cells3,4 which had not had prior antigenic experience but which were capable of contributing to a specific immune response such as formation and secretion of antibody, and (3) cells coated non-specifically with cytophilic antibody.
201 citations
184 citations
TL;DR: In this paper, a geochronological and paleomagnetic investigation of the volcanic island of Mauritius is reported, which reveals that the main shield volcano was built subaerially between about 7.8 and 6.8 m.y.
Abstract: Results of a geochronological and paleomagnetic investigation of the volcanic island of Mauritius are reported. Potassium-argon dates indicate that the main shield volcano was built subaerially between about 7.8 and 6.8 m.y. ago in the early Pliocene. Some evidence is presented for caldera formation following the construction of the volcanic shield. Profound erosion subsequently destroyed much of the volcano, leaving only peripheral steep-sided massifs. Lavas of the Younger Volcanic Series were erupted from about 3.5 m.y. ago until less than 0.2 m.y. ago, flooding the denuded stumps of the shield volcano. This activity was intermittent and a hiatus is recognized from about 2 to 0.7 m.y. ago, which we have taken as the break between the eruption of the Early and Late Lavas of the Younger Volcanic Series. The mean directions of magnetization of the three groups of lavas are not significantly different from one another and are close to an axial dipole direction. The combined paleomagnetic and dating studies on the lavas also yield further information on the geomagnetic polarity time scale; 16 results on rocks with ages lying between 3.5 and 0.17 m.y. are consistent with the established scale for this period of geological time. Of particular significance are results that confirm the Mammoth reversed event at 3.0 m.y. ago, and the age of the boundary between the Gauss normal and Gilbert reversed polarity epochs at 3.35 m.y. Nineteen results were obtained on rocks whose ages are between 4.6 and 7.9 m.y., and these data generally are consistent with the polarity time scale based upon extrapolations from the sea-floor spreading hypothesis. The evolution of the Mascarene Islands, comprising Mauritius, Reunion and Rodriguez is briefly reviewed and it is concluded that each island had developed independently, and that no correlation of age with respect to distance from the Mid-Indian Ocean Ridge is observed. The volcanism that has built Mauritius and Reunion may be a continuation of the development of the Mascarene Plateau with migration of the activity generally southward with time.
178 citations
147 citations
TL;DR: In the case of the Rangitoto volcanic island, the radiocarbon, geological and botanical evidence unequivocally showed that it was active and was probably built during the last 1000 years as discussed by the authors.
TL;DR: In this paper, a two stage model involving sea-floor spreading and transportation of the oceanic crust down the dipping seismic plane into the mantle where it is remelted to form andesites is proposed.
Abstract: Abundance data for Cs, Rb, Tl, Ba, Pb, Sr, the rare earths, Th, U, Zr, Hf, Sn, Nb, Mo, Mn, Cu, Co, Ni, Sc, V, Cr, Ag, Sb and the major elements are reported for two andesites and a dacite from Saipan, nine andesites and a dacite from Bougainville and two andesites from Fiji. The Saipan rocks are low-K varieties and contain notably low abundances of Rb, Ba, Th and U and have rare earth patterns subparallel to chondritic patterns. The Bougainville andesites include low-Si and high-K varieties which have higher concentrations of the large cations. The Fijian samples are close to the average circum-Pacific andesite and have rareearth patterns sub-parallel to those of sedimentary rocks. All the andesites contain characteristically low ( 10. These data preclude derivation of calc-alkaline rocks by mixing of upper crustal material or by fractional crystallisation from basaltic parents. A two stage model is proposed involving sea-floor spreading and transportation of the oceanic crust down the dipping seismic plane into the mantle where it is remelted to form andesites.
TL;DR: The Delegate breccia-nephelinite pipes as discussed by the authors contain abundant two-pyroxene granulite, garnet granulites and fassaite eclogite inclusions and rare spinel pyroxenite, peridotite and charnockite.
Abstract: Basic breccia-nephelinite pipes at Delegate (N.S.W., Australia) contain abundant two-pyroxene granulite, garnet granulite and fassaite eclogite inclusions and rare spinel pyroxenite, peridotite and charnockite inclusions.
TL;DR: The phytochemical actions of 1,10-PHENANTHROLINE and 2,2′-BIPYRIDINE HYDROCHLORIDES, QUATERNARY SALTS and METAL CHELATES and RELATED COMPOUNDS are studied.
Abstract: THE BIOLOGICAL ACTIONS OF 1,10-PHENANTHROLINE AND 2,2′-BIPYRIDINE HYDROCHLORIDES, QUATERNARY SALTS AND METAL CHELATES AND RELATED COMPOUNDS
TL;DR: It was shown that the viral envelope contains a unit membrane like that of the host cell, and an additional inner leaflet not found in the cell membrane, and a hypothesis is presented for the sequential stages in the assembly of virus particles which takes account of these and other observations.
TL;DR: In this article, the Rb-Sr method was used to find parallels between the ages of sequences in Australia and those in Peninsular India, Ceylon and Pakistan.
Abstract: Analysis of Pre-Cambrian rocks by the Rb–Sr method confirms parallels between the ages of sequences in Australia and those in Peninsular India, Ceylon and Pakistan The findings are relevant to the question of continental reassembly
TL;DR: In this article, the position of the seismic zone may be correlated with the chemistry of the rocks and in the New Guinea Arc the plane dips towards the continent, in the Solomon Island Arc (Bougainville section), in the southern section (New Georgia-Guadalcanal) it is almost vertical.
TL;DR: Two genes (ubiB and ubiD) concerned with two successive reactions in ubiquinone biosynthesis in Escherichia coli were mapped and found to be closely linked.
Abstract: Two genes (ubiB and ubiD) concerned with two successive reactions in ubiquinone biosynthesis in Escherichia coli were mapped and found to be closely linked. Mutant strains of E. coli carrying the ubiB− and ubiD− alleles were shown to accumulate 2-octaprenylphenol and 3-octaprenyl-4-hydroxybenzoic acid, respectively. These compounds were isolated and identified by using nuclear magnetic resonance and mass and infrared spectroscopy. Cell extracts from the mutant strain carrying the ubiD− allele lack 3-octaprenyl-4-hydroxybenzoate decarboxylase activity.
TL;DR: This paper considers the solution of the corresponding nonlinear minimax approximation problems, by solving a sequence of linear discrete T-problems.
Abstract: are now well understood. In particular the equivalence of (i) with a linear programming problem permits its solution under very general conditions (see, for example, Kelley (1959), Stiefel (1960), Rice (1964), Osborne and Watson (1967, 1968)). In this paper, we consider the solution of the corresponding nonlinear minimax approximation problems, by solving a sequence of linear discrete T-problems. Certain properties of the solution of the linear problem are required, in particular, properties relevant to its solution as a linear programming problem, and these we now summarise. If we write r=f-Aa, (1.1)
Journal Article•
TL;DR: Many new Rb-Sr age determination analyses are reported for the crystalline complex of southern Peninsular India as mentioned in this paper, which are mostly total-rock ages, often isochrons.
Abstract: Many new Rb-Sr age determination analyses are reported for the crystalline complex of southern Peninsular India. These are mostly total-rock ages, often isochrons. Data are still insufficient for a reliable geochronology. Rocks of apparent ages ranging from over 3000 m.y. to 720 m.y. have been dated, and a lower Palaeozoic event reflected in mineral ages of about 500 m.y., known to have affected all Ceylon and much of the east coast of India, has been found as far north as Coimbatore. The oldest rocks have been found in Kerala, the Nilgiri Hills and southern Mysore. One age of 2700 m.y. has been found in Kerala. The craton of Mysore-Hyderabad has an age of at least 2585 ± 40 m.y., which is the apparent age of the Peninsular Gneiss over a wide area. The age of the Dharwar System remains uncertain, although the lavas near Chitradurga give an isochron at 2345 ± 60 m.y. The Chitradurga Granite has an age between 2450 and 2400 m.y. The Closepet Granite presents difficulties arising from its poor definition, but contains components between 2400 and 2000 m.y. Rocks of about 2100 m.y. occur in Kerala and western Tamizhagam, and could be present in Mysore, where an event at this time is recorded by biotite. The Chamundi Hill Granite of Mysore city, and a granite from the Ramanathapuram District of Tamizhagam give 790 ± 60 and 720 m.y. respectively, suggesting the possibility of widespread if sporadic intrusion in the southern half of the region at about this time. There is no real evidence yet of any major reflection of the Vijayan retrogressive metamorphism of Ceylon at 1140 m.y., except possibly in the intrusion of the Sivamalai soda-syenite. However, the known mineral ages of about 1690, 1650 and 1150 m.y. along the west coast suggest repeated marginal mobility of the Mysore-Hyderabad craton otherwise stable since about 2000 m.y. though intruded repeatedly by several dyke suites not yet dated. Much further sampling is needed, as well as the combination of several methods of dating. To facilitate this, modern geological and tectonic maps of medium scale are very desirable.
TL;DR: In this paper, methods of testing for a change in the scale parameter in one margin, using the other variate as a control, are described and the corresponding extension to cross-over experiments briefly outlined.
Abstract: SUMMARY In some experimental situations where the use of a covariate could increase the precision of the experiment the distributions of the test variate and the covariate are highly nonnormal. Some of these cases can be analysed by using a bivariate P distribution which is here defined. Methods of testing for a change in the scale parameter in one margin, using the other variate as a control, are described and the corresponding extension to cross-over experiments briefly outlined.
TL;DR: The vanadium content of calc-alkaline andesites averages 175 ppm and is similar to that observed in basalts (average 200 ppm) but is much lower than the nickel contents of alkali or tholeiitic basalts.
TL;DR: In this chapter, most of the named plant viruses and their possible or known relationships are discussed, and a classification was computed for about 140 viruses using several of their properties.
Abstract: Publisher Summary In any new and active branch of research, such as the study of plant viruses, various ways of interpreting and classifying information are tried before underlying patterns are revealed, and a stable and useful classification can be made In this chapter, most of the named plant viruses and their possible or known relationships are discussed Some viruses seem quite distinct and do not appear closely related by their properties to any other viruses, whereas others fall into well-defined groups, such as the potato virus Y group, which already contains more than two dozen viruses The chapter provides information about viruses transmitted by mites (eriophyidae, acarina), viruses transmitted by white fly (aleyrodidae, hemiptera), viruses transmitted by aphids (aphididae, hemiptera), viruses transmitted by leafhoppers (auchenorrhyncha, hemiptera), viruses transmitted by mealybugs (coccidae, hemiptera), viruses transmitted by flea beetles (coleoptera, insecta), viruses transmitted by fungi (chytridiales and plasmodiophorales), viruses transmitted by mirid, piesmid, or tingid bugs (gymnocerata hemiptera), viruses transmitted by nematodes (nematoda), viruses transmitted by psyllas (psyllidae, hemiptera), viruses transmitted by thrips (thysanoptera), and viruses with no known vectors A classification was computed for about 140 viruses using several of their properties The viruses chosen were some of those whose particles have been identified by electron microscopy
TL;DR: It is suggested that the ability of an animal to distinguish between "self" and "not-self" components may operate at two distinct levels; one involves the recognition of foreign antigens, and the other the Recognition of cells derived from genetically related but not identical animals.
Abstract: Normal lymphoid cells obtained from animals that are phylogenetically unrelated or only distantly related to the chicken do not initiate graft versus host reactions when introduced into chicken embryos. Such cells are capable of mounting a reaction against the embryo if the donor animal is first immunized with chicken tissues. However, the reaction produced by immune xenogeneic lymphoid cells has a different pathogencsis to that produced by normal allogeneic cells. The transfer of adult blood leucocytes to syngeneic embryos will confer on the embryo the ability to reject transplanted allogeneic tissue, but will not confer on the embryo the ability to make antibody or to reject the transplants of some xenogeneic tissues. The latter type of transplant can be rejected if cells allogeneic with respect to the graft are introduced into the embryo. Allogeneic transplants are only rejected by embryos treated with adult blood leucocytes if the transplant contains a relatively large component of reticular tissue. Treatments, such as -irradiation, that reduce the amount of reticular tissue in the graft protect it from transplantation damage in treated embryos. The in vitro interaction between populations of lymphocytes obtained from different animals has the same specificity as graft versus host reactions in so far as lymphocyte populations obtained from sheep are not stimulated by lymphocytes obtained from a different species of animal such as the rat or goose, but are stimulated by allogeneic lymphocytes. The treatment of one population of sheep lymphocytes with -rays will destroy their capacity to stimulate allogeneic lymphocytes without affecting the antigenicity of the lymphocytes. It is suggested that the ability of an animal to distinguish between "self" and "not-self" components may operate at two distinct levels; one involves the recognition of foreign antigens, and the other the recognition of cells derived from genetically related but not identical animals.
TL;DR: In this article, a theoretical version of Bath9s law is derived on the assumption that aftershock magnitudes are independently and exponentially distributed, and it is shown by reference to Utsu9s table of Japanese aftershock sequences that the discrepancies may be due to bias introduced by the method of selecting the data for study.
Abstract: A theoretical version of Bath9s law is derived on the assumption that aftershock magnitudes are independently and exponentially distributed. The results are not fully in agreement with the commonly accepted picture of Bath9s law, but it is shown by reference to Utsu9s table of Japanese aftershock sequences that the discrepancies may be due to bias introduced by the method of selecting the data for study.
TL;DR: The results indicate that antibody to neuraminidase does not exert a direct effect on viral maturation, but inhibits the detachment of viral progeny from cell surface receptors.
Abstract: Antiserum to a recombinant between an Ao and an A2 influenza virus had no detectable antibody against an A2 virus in standard hemagglutination-inhibition tests, and inhibited 95% of viral neuraminidase activity at a 1 to 400 dilution. However, on mixing virus with antiserum, a drop of up to 90% in hemagglutinin titer was observed. The effects of ultrasonication and direct electron microscopic examination indicated that the antiserum caused aggregation of virus particles. When antiserum was added to A2 virus-infected chick embryo fibroblasts, release of virus appeared markedly inhibited. After ultrasonication to disrupt aggregates, an increase in released hemagglutinin was observed, but the resulting level was considerably lower than that in control cultures containing normal rabbit serum. In thin sections of infected cells, similar numbers of virus profiles were observed in control and antiserum-treated cultures. A marked increase in release of hemagglutinin was noted if receptor-destroying enzyme was added to antiserum-treated cultures. The results indicate that antibody to neuraminidase does not exert a direct effect on viral maturation, but inhibits the detachment of viral progeny from cell surface receptors.
TL;DR: In this paper, the absolute lead isotope composition of the UBC No. 1 Standard has been estimated with the double-spike measurement technique, which has been normalized to the Catanzaro values for SRM 981, must therefore be close to absolutely correct.