Showing papers by "University of Newcastle published in 1983"

Derivative constraints for broad-band element space antenna array processors

Abstract: In this paper a class of linear constraints, also termed as derivative constraints, which is applicable to broad-band element space antenna array processors, is presented. The performance characteristics of the optimum processor with derivative constraints are demonstrated by computer studies involving two types of array geometries, namely linear and circular arrays. As a consequence of derivative constraints, the beam width in the look direction can be made as broad as desired and the beam spacings can be selected without fear of substantial signal suppression in the event of signal arrivals between beams. However, this increased beam width is achieved at the price of reducing array gain.

A thermodynamically consistent model of a mushy zone

Abstract: Presentation d'une theorie compatible avec la thermodynamique permettant la construction de modele d'une zone de melange de phases solide et liquide pouvant apparaitre lors du refroidissement d'un alliage binaire fondu. Application a un probleme de solidification monodimensionnel

On the organized motion of a turbulent plane jet

Abstract: Measurements of space–time correlations of longitudinal and normal velocity fluctuations and of temperature fluctuations support the existence of counter-rotating spanwise structures appearing alternately on opposite sides of the jet centreline in the self-preserving region of the flow. The frequency of these structures closely satisfies self-preservation. The asymmetric arrangement of the structures is first observed downstream of the position where the jet mixing layers nominally merge but upstream of the onset of self-preservation. Closer to the jet exit, the space–time correlations indicate the existence of spanwise structures that are symmetrical about the centreline.

Cigarette Smoking and Drug Use in Schoolchildren: IV—Factors Associated with Changes in Smoking Behaviour

Abstract: Factors associated with changes in the smoking behaviour of approximately 6000 schoolchildren (two cohorts aged between 10 and 12 years in 1979) over 12 months are described. They were measured twice as part of a randomized controlled trial of a smoking prevention programme. Four groups were defined: (a) those who became smokers (adopters); (b) those who remained non-smokers; (c) those who became non-smokers (quitters), and, (d) those who remained smokers. Personal and social variables were ordered using a logistic regression model according to the strength of their association with adopting and quitting smoking. Factors distinguishing adopters from children who remained non-smokers were, being a member of the older cohort, having friends who smoke, having siblings who smoke, approving of cigarette advertising and having a relatively large amount of money to spend each week. Factors distinguishing quitters from children who continued to smoke were, having siblings who do not smoke, being a member of the younger cohort, disapproving of cigarette advertising and having a relatively small amount of money to spend each week. Initial attitude scores were indicative of future smoking behaviour and where smoking behaviour changed, attitudes also changed so that the two remained congruent. The younger cohort improved their knowledge of smoking hazards over the year irrespective of their smoking behaviour. The older cohort showed significant differences in knowledge which were dependent upon smoking category, with 1980 smokers having lower knowledge scores than non-smokers and showing an apparent decrement in their previous knowledge.

Depolarisation-dependent protein phosphorylation in rat cortical synaptosomes: factors determining the magnitude of the response.

Abstract: The sequence of molecular events linking depolarisation-dependent calcium influx to the release of neurotransmitters from nerve terminals is unknown; however, calcium-stimulated protein phosphorylation may play a role. In this study the incorporation of phosphate into proteins was investigated using an intact postmitochondrial pellet isolated from rat cerebral cortex. The rate and relative incorporation of label into individual phosphoproteins depended on the prelabelling time and buffer concentrations of calcium and phosphate. After prelabelling for 45 min, depolarisation caused a greater than 20% increase in the labelling of 10 phosphoproteins, and this initial increase was maximal with 41 mM K+ for 5 s, or 30 microM veratridine for 15 s, in the presence of 1 mM calcium. Both agents also led to an initial dephosphorylation of four phosphoproteins. Depolarisation for 5 min led to a significant decrease in the labelling of all phosphoproteins. All of the depolarisation-stimulated changes in protein phosphorylation were calcium-dependent. The depolarisation conditions found to optimally alter the phosphorylation of synaptosomal proteins find many parallels in studies on calcium uptake and neurotransmitter release. However, the uniform responses of such a large number of phosphoproteins to the multitude of depolarisation conditions studied suggest that the changes could equally well relate to recovery events such as biosynthesis of neurotransmitters and regulation of intraterminal metabolic activity.

Contracture of guinea‐pig ileum on withdrawal of methionine5‐enkephalin is mediated by substance P

Abstract: The effects of methionine5-enkephalin (Met-enkephalin, ME) 5 X 10(-8)-5 X 10(-6) moll-1) were investigated on the resting guinea-pig ileum. While in contact with the ileum, ME reduced the natural tone and movements, but following washout a contracture occurred which increased with increasing duration of the contact period from 0.5 to 32 min and with increasing concentration of the ME present during the contact period. The washout contractures after 2 min contact with ME, 10(-6) moll-1, were abolished by naloxone, 10(-6)moll-1, added prior to the addition of ME, atropine, 5 X 10(-6)moll-1 and the substance P (SP) antagonist, (D-Pro2, D-Phe7, D-Trp9)-SP, 10(-5)moll-1 and were reduced by 5-hydroxytryptamine (5-HT)-autodesensitization. Washout contractures following 32 min contact with ME, 10(-6)moll-1, were significantly inhibited by the SP antagonist and naloxone and were abolished by a combination of atropine and the SP antagonist, but were not significantly reduced by atropine alone or by 5-HT-desensitization. Contractures of ileum occurred on addition of naloxone to ileal segments exposed to ME for 2 or 32 min. These contractures were also inhibited by the SP antagonist but a combination of atropine and SP-desensitization was required to abolish them. It was concluded that gut dependence occurs following very brief exposure to an opioid and that SP plays a central role in the withdrawal response precipitated either by washout or addition of naloxone.

Extraction of copper, lead, zinc or cadmium ions sorbed on calcium carbonate

Abstract: The amount of sorbed metal ion released from CaC03 by 16 different extractants was found to vary with the chemical nature of the solution and the metal ion involved In general, acid solutions dissolved a high proportion of both substrate and Cu, Ph, Cd coatings; complexing agents dissolved the same coatings but left most of the calcite; and competing cations (eg NH4+, Ca2+) displaced primarily chemisorbed Cd and Cu In Zn studies, little metal ion was retrieved by any extractant due to the limited solubility of the coatings formed at pH < 77

Deterministic convergence of a self-tuning regulator with covariance resetting

Abstract: A recent paper by Cordero and Mayne has established convergence of a self-tuning regulator with variable forgetting factor. The short paper shows that a similar result can be proved for ordinary recursive least squares with covariance resetting.

An Easily Testable Design of Programmable Logic Arrays for Multiple Faults

Abstract: In this paper, the problem of fault detection for multiple faults in programmable logic arrays (PLA's) is discussed. An easily testable design of PLA's has been proposed which has the following properties: 1) for a PLA with n inputs, m product terms, there exists a test set such that the test patterns do not depend on the function realized by the PLA; 2) the number of tests to detect multiple stuck type and cross point faults is m(2n + 1) + 4n + 4; 3) the number of additional pins for the testable design is 3; 4) the design philosophy is compatible with the built-in-testing approaches.

Plastid number and plastid structural changes associated with tobacco mesophyll protoplast culture and plant regeneration.

Abstract: Mesophyll protoplasts were isolated from Nicotiana tabacum L cv Xanthi, and cell-colony formation induced in liquid culture The plastid changes associated with the morphogenetic sequence from mesophyll protoplast to whole plant were examined Minor ultrastructural changes in the plastids were evident after 1 d of culture, but by 8 d (four-to-eight-cell stage) the plastids were small, there was much less thylakoid membrane appression, and many prominent plastoglobuli were also present Plastid-division figures were evident at this point of time and it was common to find plastids clustered around the nucleus A typical proplastid was the dominant plastid type in the cultured cells from about 11 d until about five weeks when large amyloplasts and pregranal plastids were observed Normally structured chloroplasts were present in the regenerated plant There was no plastid division until the four-cell stage, with plastid numbers per cell approximately halving at each cell division, then stabilising around 12 per cell during cell-colony development, a number typical of meristematic cells Though nucleoids were always present, their numbers in the plastids were reduced by the eight-cell stage

Studies of the interfacial kinetics of the reaction of nitrogen with liquid iron by the15N-14N isotope exchange reaction

Abstract: The rate of dissociation of N2 on high purity liquid iron and iron-sulfur alloys between 1550 and 1650 °C has been studied by means of the15N-14N exchange reaction. It is shown that the rate constants at given sulfur concentrations are consistent with those for the absorption of nitrogen into iron-sulfur alloys, indicating a common rate determining step. The rate constant for high purity liquid iron, in units of mol cm−2 s−1 aim−1, is given by: logk f = −340/T − 1.38. The rate constant is found to be independent of carbon concentration up to about 4.3 wt pct and to be closely consistent with ideal chemisorption kinetics. The results are combined with those of previously published studies to give rational equations for the apparent rate constants for Fe-S and Fe-O alloys. Consistent values for the adsorption coefficients at 1600 °C for sulfur and oxygen are deduced to be about 130 and 220, respectively, for a standard state of the 1 wt pct ideal solution.

The Application of General Systems Theory to an Analysis of Marketing Systems

Abstract: The evolution of marketing can be modeled within the paradigm of general systems theory. Using this approach marketing thought can be described in terms of the attempt by organizations to become mo...

The polymorphism of the vitamin D-binding protein (Gc); Isoelectric focusing in 3 M urea as additional method for identification of genetic variants

Abstract: Since the last report numerous new DBP (Gc) variants have been observed; at present a total of 84 different mutants can be distinguished. Several of them have similar electrophoretic mobilities and/or isoelectric points by conventional isoelectric focusing (IEF). IEF in polyacrylamide gels in the presence of 3 M urea is a convenient and effecient method for the detection of hidden variation.

Model reference adaptive control of system having purely deterministic disturbances

Abstract: This note presents results relating to the adaptive control of linear time invariant systems having purely deterministic disturbances such as sine waves, biases, etc. Two key points are made. First, it is shown that the usual ARMA model used in adaptive control can also include a description of purely deterministic disturbances. Second, it is shown that the existing convergence theory for adaptive control schemes can be extended in a very straightforward way to the case where disturbances are present.

Interaction Region of a Two-Dimensional Turbulent Plane Jet in Still Air

Abstract: Mean velocity and temperature profiles in the interaction region of a slightly heated turbulent plane jet with initially laminar boundary layers do not deviate perceptibly from the far field self-preserving profiles when the centreline mean velocity/temperature and mean velocity/temperature half-widths are used as the appropriate normalising scales. On the jet centreline, the maximum value of the ratio of rms to mean temperature is larger by a factor of almost two than the corresponding ratio for any of the three velocity fluctuations. The probability density function of temperature on the centreline and at a distance of twelve slit widths from the nozzle reveals the presence of room temperature fluid and also of fluid which is at the jet exit temperature. Spectral density functions of temperature exhibit a peak up to a distance of about twelve nozzle widths. Space-time correlations of velocity fluctuations indicate that the vortical structures, symmetrical with respect to the centreline, which are observed at the beginning of the interaction are replaced by structures, asymmetrical with respect to the centreline, towards the end of the interaction region.