Showing papers by "Australian National University published in 1968"

Genesis of the calc-alkaline igneous rock suite

Abstract: A high pressure experimental study of the partial melting fields of synthetic high-alumina olivine tholeiite, high-alumina quartz tholeiite, basaltic andesite, andesite, dacite and rhyodacite under dry and wet $$\left( {P_{{\text{H}}_{\text{2}} {\text{O}}} < P_{{\text{LOAD }}} } \right)$$ conditions has been conducted in order to investigate possible origins of the calc-alkaline series from the upper mantle Detailed analyses of crystallizing phases using the electron microprobe has enabled calculation of the liquid line of descent in these compositions at various pressures At 27–36 kb garnet and clinopyroxene are the liquidus or near-liquidus phases in dry tholeiite, basaltic andesite and andesite, while quartz is the liquidus phases in dry dacite and rhyodacite Under wet conditions at 27 kb garnet, not quartz, is the liquidus phase in the dacite Qualitatively these results show that the low melting fraction of a quartz eclogite at 27–36 kb under dry conditions is of andesitic composition whereas under wet conditions it is rhyodacitic or granodioritic At these pressures under dry conditions the andesite liquidus lies in a marked low temperature trough between the more basic and more acid compositions Quantitatively, the calculated compositions of liquid fractionates for varying degrees of melting of the quartz eclogite bulk composition broadly follow the calc-alkaline trend At 9–10 kb under wet conditions $$\left( {P_{{\text{H}}_{\text{2}} {\text{O}}} < P_{{\text{LOAD }}} } \right)$$ sub-silicic amphibole and pyroxenes are the near-liquidus phases in tholeiite and basaltic andesite compositions Calcic plagioclase and garnet occur nearer the solidus The calculated liquid fractionates follow the calc-alkaline trend and demonstrate that the calc-alkaline series may be derived by the partial melting of amphibolite at lower crustal depths under wet conditions $$\left( {P_{{\text{H}}_{\text{2}} {\text{O}}} < P_{{\text{LOAD }}} } \right)$$ , Or by the fractional crystallization of a hydrous basalt magma at similar depths These experimental results support two complementary hypotheses for the derivation of the calc-alkaline igneous rock suite from the mantle by a two stage igneous process In the first stage of both hypotheses large piles of basalt are extruded on the earth's surface Subsequently this pile of basalt may, under dry conditions, transform to quartz eclogite, sink into the mantle and finally undergo partial melting at 100–150 kms depth This partial melting gives rise to the calc-alkaline magma series leaving a residuum of clinopyroxene and garnet Alternatively, if wet conditions prevail in the basalt pile and the geotherms remain high, partial melting of the basalt may take place near the base of the pile, at about 10 kb pressure $$\left( {P_{{\text{H}}_{\text{2}} {\text{O}}} < P_{{\text{LOAD }}} } \right)$$ The liquids so formed constitute the calc-alkaline suite and the residuum consists of amphibole, pyroxenes and possibly minor garnet and calcic plagioclase Both models may be directly linked to the hypothesis of sea-floor spreading

A pharmacological study of the depression of spinal neurones by glycine and related amino acids

Abstract: An analysis has been made in anaesthetised cats of the depression by glycine and related amino acids of the firing of spinal dorsal horn interneurones, Renshaw cells and cortical neurones. In general, electrophoretically administered glycine was a more potent depressant of interneurones than GABA. The reverse was true for cortical neurones, whereas these two amino acids were approximately equally effective upon Renshaw cells. Strychnine blocked the depressant action of α- and β-amino acids, but not that of γ- and higher ω-amino acids. Only convulsants having a strychnine-like effect on spinal post-synaptic inhibition blocked the action of glycine. The depression of spinal neurones produced by glycine or GABA was not affected by structural analogues of glycine and GABA that were not depressants, or by substances influencing amino acid transport systems. Some evidence was obtained for the enzymic inactivation of electrophoretically administered glycine in spinal tissue. The results are discussed in terms of the involvement of a glycine-like amino acid as a major spinal inhibitory transmitter.

The hyperpolarization of spinal motoneurones by glycine and related amino acids.

Abstract: Electrophoretically administered glycine, β-alanine and GABA hyperpolarize spinal motoneurones in cats anaesthetized with pentobarbitone The reversal potential for these hyperpolarizations is similar to that of inhibitory postsynaptic potentials Alterations in intracellular K+ and Cl− ion concentrations, and intracellular injection of a series of anions of different hydrated ion size, affect inhibitory and amino acid potentials in the same fashion Hence it is probable that glycine, β-alanine and GABA produce an alteration in membrane permeability similar to that produced by spinal inhibitory synaptic transmitters Strychnine reversibly blocks the action of inhibitory transmitters, glycine and β-alanine, but is without effect on the hyperpolarizing action of GABA These results indicate that glycine may be a major spinal inhibitory transmitter, in which case strychnine affects spinal postsynaptic inhibition by limiting the action of glycine upon subsynaptic inhibitory receptors

Responses to moving slits by single units in cat striate cortex

Abstract: A quantitative study has been made of the responses to moving slit stimuli by single units in the cat striate cortex whose receptive fields lay within 5° of the visual axis. Special attention was given to finding the optimal stimulus parameters including slit width, length, orientation and speed. The analysis was largely based on averaged response vs. time histograms. Using the classification of simple and complex responses types, the units were further subdivided on the basis of the number of modes in the response and on the presence or absence of directional selectivity. Simple unimodal units with directional selectivity (SUDS) had the most specific stimulus requirements and nearly always had zero background activity. Complex units usually had a high level of background activity. SUDS units also showed a preference for horizontally- and vertically ****-orientated stimuli. Whenever the response survived reversal of contrast the directional selectivity remained independent of the change. Optimal stimulus speeds varied widely from unit to unit with a mean at 4°/sec: simple bimodal units and complex units tended to have higher optimal stimulus speeds and responded over a wider range of speeds than did simple unimodal units. While SUDS units with very small receptive fields tended to prefer slowly moving stimuli, in general there was no correlation between receptive field size and optimal stimulus speed.

Binocular interaction on single units in cat striate cortex: simultaneous stimulation by single moving slit with receptive fields in correspondence.

Abstract: Averaged responses of binocularly-activated single units of the striate cortex of paralysed cats were studied using a single, moving visual stimulus and prisms of variable power to control the visual direction of each eye. Binocular facilitation, summation or occlusion of the monocular response occurred, depending on the type of unit and on the prism setting. Binocular stimulating conditions were optimal for a given unit when the prism setting superimposed, or very nearly superimposed, the receptive field pair on the same plane as the moving stimulus. Under these optimal conditions, most units showed summation or facilitation of the monocular responses, with a minority showing occlusion. When the prism setting was changed from the optimal value, binocular occlusion could be demonstrated in all units. Curves plotting binocular response against prism setting provided information on the specificity, temporal properties and symmetry of the binocular response. The binocular response of simple units showed great specificity with a sharply defined peak on the response curve at a particular prism setting. There was variation from one simple unit to another in the exact prism setting required to give the optimal response. A proportion of complex units, despite large receptive field size, showed binocular specificity with a very narrow range of facilitation, of the same order as that shown by simple units. Other complex units showed binocular facilitation over a wide range of prism settings.

An approach to the study of phase separation in ternary aqueous systems.

Abstract: 1. Simple thermodynamic expressions are used to describe the properties of uncharged binary and ternary polymer solutions, in particular the sedimentation equilibrium of binary systems and the osmotic pressures and ‘incompatible’ phase separations of ternary systems. 2. Sedimentation-equilibrium experiments were performed on four samples of dextran and two of polyethylene glycol. The critical points of the phase diagrams were determined for the mixed solutions of polyethylene glycol–dextran–water and of polyethylene glycol–bovine serum albumin–0·2m-sodium chloride solution. Osmotic pressures were measured on a single-phase mixed solution of a polyethylene glycol and a dextran. By use of the simple thermodynamic expressions consistent values of second virial and interaction coefficients for the materials used were obtained from these experiments. 3. The interpretation of the values of the second virial and interaction coefficients, on the basis of three models of molecular interaction, is discussed.

Antiviral Activity of Antiserum Specific for an Influenza Virus Neuraminidase

Abstract: Antiserum specific for influenza A2 neuraminidase was produced by immunization of rabbits with the purified enzyme which had been isolated by electrophoresis from the proteins of a detergent-disrupted A0A2 influenza virus recombinant [X-7 (F1)]. This recombinant contained hemagglutinin of the A0 subtype and A2 neuraminidase. Antiserum to the isolated A2 neuraminidase did not react in any of four serological tests with A0 or A2 subtype viruses that lacked the A2 enzyme. In contrast, the antiserum inhibited the neuraminidase activity only of wild-type and recombinant viruses containing the A2 enzyme, regardless of the nature of their hemagglutinin proteins. The antiserum caused hemagglutination-inhibition of some, but not all, viruses bearing the A2 enzyme, and it reduced the plaque size or plaque number of all viruses tested that contained A2 neuraminidase. In the chick embryo and in cell culture, low dilutions of antiserum reduced the yield of virus. True neutralization of virus in the chick embryo did not occur. We conclude that an antiserum specific for A2 neuraminidase influenced the yield and release of virus from influenza virus-infected cells.

The Ordovician System

Abstract: This chapter provides an overview of the Ordovician systems. With the advent of the Ordovician, comes a more complete record of the history of the Tasman Orthogeosyncline. In this structure, it is only in eastern Queensland and northeastern New South Wales that there are extensive occurrences of unfossiliferous rocks of possible Ordovician age. Deposition continued over large parts of the northwestern part of the continent, and in the Amadeus Basin where, except for the uppermost Ordovician, a more or less continuous history may be deciphered. In New Zealand, well-defined Ordovician rocks of both the graptolitic and shelly facies are known in the South Island, namely, in the northwest Nelson region and in the southwest Fiordland. It is known that the graptolite-bearing succession of both these localities, though somewhat less complete, corresponds very closely to that in Victoria. In the Ordovician, as in the Cambrian, seas probably covered the three basins—Officer, Amadeus, and Ngalia basins—and at least some of the intervening areas. In the Officer Basin, probable Ordovician rocks are known along the northern edge, where they dip basinward but little is yet known of their extent. The presence of Ordovician sediments in the Ngalia Basin has yet to be demonstrated.

A study of the alcohol-tolerance effect and an introduction of a new behavioural technique

Abstract: The alcohol-tolerance effect was studied with 12 male white rats. A two-turn task in a temporal circular maze, which possesses some advantageous features for behavioural drug studies, was used as a behavioural technique. The results show that Ss that had the repeated opportunities for running the maze while under the influence of alcohol perform much better than Ss that had merely been accustomed to alcohol but trained in a sober state. This result suggests that the tolerance effect could not be accounted for entirely in terms of physio-biochemical mechanisms, some behavioural principles may need to be invoked.

Influence of Temperature on Isometric Contractions of Rat Skeletal Muscles

Abstract: THE influence of temperature on isometric contractions of rat skeletal muscles in vitro has been determined for fast extensor digitorum longus muscles (EDL) and slow soleus muscles (SOL) from 4 week old female Wistar rats. Isometric contractions were recorded with the long axis of the muscle vertical, with one tendon tied to the frame below and the other tendon tied to a short steel wire connexion which linked it with the tension transducer above. The compliance of the transducer (Statham, Gl-80-350) and the steel wire connexion to the muscle was 4.5 × 10−5 cm/g and the natural frequency of vibration was 2 kHz. The muscle was immersed in about 100 ml. of fluid (137 mM Nacl; 5 mM KCl; 2 mM CaCl2; 1 mM MgCl2; 1 mM NaH2PO4; 2 g/l. of NaHCO3 and 2 g/l. of glucose) which was bubbled continuously with 95 per cent O2 and 5 per cent CO2. Neuromuscular transmission was blocked by adding 2.0 × 10−5 g of tubocurarine chloride/ml. of bath fluid. The muscles were stimulated directly by a transverse electrical field of 15 V/cm for 0.2 or 0.3 ms applied to the bath fluid by “massive” bright platinum electrodes set about 1 cm apart1. All recordings were made with the muscle set at the optimal length determined for twitch contractions at 20° C.

The shoshonite association: A review

Abstract: The absarokite‐shoshonite‐banakite series described from Yellowstone Park by Iddings and the ciminite‐toscanite series described from western Italy by Washington are compared. In both regions these rocks are associated with leucite‐bearing rocks, potassium‐rich trachytes and with andesitic rocks with above average potassium. A similar association of rock‐types is described from Indonesia and several other regions including the Rift Valley of Africa where, at Bufumbira, Holmes & Harwood have described members of the absarokite‐shoshonite‐banakite, potassium trachytes and leucite rocks. It is concluded that the absarokite‐shoshonite‐banakite series and the ciminite‐toscanite series are parts of a single rock association here called the shoshonite association. Intrusive members, such as monzonites, are also briefly discussed. The relation of the shoshonite association to the tholeiite, alkali basalt, calcal‐kaline and carbonatite associations are examined and an attempt is made to relate these to te...

An unsolved problem on the powers of 3/2*

Abstract: Let α be an arbitrary positive number. For every integer n ≦ 0 we can write where is the largest integer not greater than , i.e the integral part of , and r n is its fractional part and so satisfies the inequality

Origin of garnet phenocrysts in calc-alkaline rocks

Abstract: A large number of garnet phenocrysts from Palaeozoic rhyodacites and granodiorite porphyrites from Central and Northeastern Victoria have been analyzed using the electron microprobe. These garnets, from an area of several thousand square miles, are very uniform in composition (dominantly almandine, with subordinate pyrope and minor grossular and spessartine). They show minor zoning with a very thin outer rim slightly richer in almandine and spessartine than the remainder of the phenocryst. They are surrounded by a complex intergrowth of cordierite and hypersthene forming a reaction rim. Resorbed quartz phenocrysts are typically associated with the garnet phenocrysts. The uniform composition, the conspicuous size and the subhedral-euhedral form of the garnet phenocrysts indicate that they crystallized directly from the acid calc-alkaline magma at an early stage of its crystallization. High pressure experimental work on a natural garnet-bearing rhyodacite glass demonstrates that almandine-rich garnet and quartz are near-liquidus phases at 18 and 27 kb \(\left( {P_{{\text{H}}_{\text{2}} {\text{O}}} < P_{{\text{LOAD }}} } \right)\), but garnet does not appear until well below the liquidus at 9 kb. A comparison of the composition of the experimentally crystallized garnets with the natural garnets suggests that these acid calc-alkaline magmas began to crystallize at pressures between 9 and 18 kb, i.e. at depths corresponding to the lower crust or upper mantle.

Trace and minor element geochemistry of the rhyolitic volcanic rocks, Central North Island, New Zealand

Abstract: Analytical data are presented for the following elements: Cs, Rb, Ba, K, Sr, Ca, Na, Fe, Mg, Cu, Co, Ni, Li, Sc, V, Cr, Ga, Al, Si, La, Y, and Zr. Eight samples were analysed by the spark source method for rare earths, Tl, Pb, Hf, Sn, Nb, Mo, Bi, and In. In addition to data on rhyolitic volcanics, a small number of intermediate volcanics and eugeosynclinal sediments were analysed for comparative purposes.

Xylem wall deposition

Abstract: Tritiated leucine, tyrosine, phenylalanine, methyllabelled methionine, and cinnamic acid were used to study xylem wall deposition and lignin formation with radioautography. Leucine did not specifically label xylem thickenings; tyrosine, phenylalanine and methionine were quite good precursors in this regard. Cinnamic acid was also readily taken up by the tissues and was very markedly concentrated in the xylem thickenings; the labelling of thickenings also occurred in empty tracheids. In developing xylem cells, labelling of the cytoplasm indicated that both the endoplasmic reticulum and Golgi bodies were associated with the wall incorporation. Vesicles probably derived from the Golgi bodies, were generally observed to aggregate in the cytoplasm near the bands of wall microtubules (even if secondary wall thickening had not commenced). Simple biochemical analyses showed that incorporation of cinnamic acid into amino acids and proteins was negligible, but some lignin oxidation products were heavily labelled. The results are related to the biochemistry of lignin synthesis, and confirm that cinnamic acid is a highly specific marker for some forms of wall synthesis.

The intraspinal distribution of some depressant amino acids.

Abstract: — —Six known depressant amino acids were found in extracts of feline spinal grey matter: α-alanine, cystathionine, GABA, glycine, serine and taurine. Of these, glycine has the distribution within the nervous system anticipated of a sub-stance whose main function is as a spinal inhibitory transmitter at strychnine-sensitive synapses, GABA being a likely transmitter candidate at any strychnine-insensitive spinal inhibitory synapses. The intraspinal distributions of α-alanine, cystathionine, serine and taurine reveal little to indicate that a synaptic role is a major function of these amino acids.

Eliminating False Alarms when detecting Seismic Events Automatically

Abstract: ONE of the principal difficulties of using the full capabilities of a seismic array and a digital computer for the automatic detection of seismic events is the number of false alarms produced by spurious noise spikes on single channels. That this is a problem is shown by the fact that the usual dynamic range between the background noise level and saturation is normally in excess of 40 dB. Large noise impulses on a single channel will therefore predominate on a phased sum of the array seismometer outputs unless the number of sensors is very large.

Plasma free fatty acid and triglyceride turnover in obesity.

Abstract: The turnover rate of plasma free fatty acids and of triglyceride in plasma very low density lipoprotein was studied in 15 obese subjects with a constant infusion of palmitic acid-1- 14 C. The plasma FFA turnover rate was significantly correlated with the plasma FFA concentration. The FFA turnover rate was also significantly related to fat mass, to fat mass as a percentage of total body weight and especially to per cent desirable weight. Since it was not related to body weight, it is evident that the plasma FFA turnover rate is related to the degree of adiposity as distinct from total body weight. The plasma triglyceride levels were on the average higher than normal in these obese subjects. The turnover rate of triglyceride in very low density lipoproteins was significantly correlated with the triglyceride concentration, and showed that increased formation was a major factor in the development of the hypertriglyceridemia.