Showing papers by "University of Sydney published in 1977"
TL;DR: In this paper, a constitutive equation is derived from a Lodge-Yamamoto type of network theory for polymeric fluids, where the network junctions are not assumed to move strictly as points of the continuum but allowed a certain "effective slip".
Abstract: A constitutive equation is derived from a Lodge—Yamamoto type of network theory for polymeric fluids. The network junctions are not assumed to move strictly as points of the continuum but allowed a certain “effective slip”. The rates of creation and destruction of junctions are assumed to depend on the instantaneous elastic energy of the network, or equivalently, the average extension of the network strand, in a simple manner. Agreement between model predictions and the I.U.P.A.C. data on L.D.P.E. is good.
1,066 citations
TL;DR: There are potentially important practical implications of hybrid dysgenesis for laboratory experimentation and care should be exercised in planning experiments involving strain crosses, and evidence that at least four of the traits are not found in nonhybrids is presented.
Abstract: A syndrome of associated aberrant traits is described in Drosophila melanogaster. Six of these traits, mutation, sterility, male recombination, transmission ratio distortion, chromosomal aberrations and local increases in female recombination, have previously been reported. A seventh trait, nondisjunction, is described for the first time. All of the traits we have examined are found nonreciprocally in F1 hybrids. We present evidence that at least four of the traits are not found in nonhybrids. Therefore we have proposed the name hybrid dysgenesis to describe this syndrome.—A partition of tested strains into two types, designated P and M, was made according to the paternal or maternal contribution required to produce hybrid dysgenesis. This classification seems to hold for crosses of strains from within the United States and Australia, as well as for crosses between strains from the two countries. Strains collected recently from natural populations are typically of the P type and those having a long laboratory history are generally of the M type. However, a group of six strains collected from the wild in the 1960's are unambiguously divided equally between the P and M types. The dichotomy of this latter group raises interesting questions concerning possible implications for speciation.—Temperature often has a critical effect on the manifestation of hybrid dysgenesis. High F1 developmental temperatures tend to increase the expression of sterility, sometimes to extreme levels. Conversely, low developmental temperatures tend to inhibit the expression of some dysgenic traits.—There are potentially important practical implications of hybrid dysgenesis for laboratory experimentation. The results suggest that care should be exercised in planning experiments involving strain crosses.
773 citations
TL;DR: The authors showed that sediment dispersal and accumulation patterns are governed by three basic effluent forces and by tide- or wave-induced processes: outflow inertia, turbulent bed friction, and outflow buoyancy.
Abstract: River-mouth process studies and comparisons of river-mouth forms from contrasting environments suggest that sediment dispersal and accumulation patterns are governed by three basic effluent forces and by tide- or wave-induced processes. Neglecting modifications by tides or waves, effluent behavior and consequent depositional patterns depend on the relative dominance of (1) outflow inertia, (2) turbulent bed friction seaward of the mouth, and (3) outflow buoyancy. Inertia-dominated effluents are characterized by fully turbulent jet diffusion, exhibit low lateral spreading angles and progressive lateral and longitudinal deceleration, and produce narrow river-mouth bars. Under most natural circumstances, inertial effects are equaled or exceeded by either turbulent bed friction or effluent buoyancy. Shallow depths immediately basinward of a river mouth enhance the effects of bed friction, causing more rapid deceleration and lateral expansion. Triangular “middle-ground” bars and frequent channel bifurcation result. Low tidal ranges, fine-grained sediment loads, and deep outlets favor strong density stratification within the lower reaches of the channels. Under such circumstances, effluents are dominated by the effects of buoyancy for at least part of the year. Buoyant effluents produce narrow distributary mouth bars, elongate distributaries with parallel banks, and few bifurcations. In macrotidal environments where tidal currents are stronger than river flow, bidirectional currents redistribute river sediments, producing sand-filled, funnel-shaped distributaries and causing linear tidal ridges to replace the distributary mouth bar. Powerful waves promote rapid effluent diffusion and decleration and produce constricted or deflected river mouths.
594 citations
TL;DR: In this article, it was shown that the work performed in the end region at the tip of a crack, where the fracture process takes place, is considered the essential work of fracture, and a constant for a particular sheet thickness.
Abstract: In a ductile material, the total work of fracture is not a material constant and linear fracture mechanics is inappropriate. The work performed in the end region at the tip of a crack, where the fracture process takes place, is considered the essential work of fracture, and a constant for a particular sheet thickness. It is shown that this essential work can be estimated from deep edge notched tension specimens by extrapolating the straight line relationship between the work of fracture and ligament length to zero ligament length.
439 citations
TL;DR: The effect of val5-angiotensin II on steady-state sodium concentration gradients (ΔcNa) was studied in rat proximal tubules by stationary micro-perfusion combined with perfusion of the peritubular capillaries to discuss the responses of the intact kidney to intra-renal infusion of angiotENSin, and to the control of tubulo-glomerular feed-back.
Abstract: The effect of val5-angiotensin II on steady-state sodium concentration gradients (deltacNa) was studied in rat proximal tubules by stationary micro-perfusion combined with perfusion of the peritubular capillaries. Angiotensin added to the peritubular perfusion fluid had a biphasic action with stimulation of sodium reabsorption at low doses (10(-12)-10(-10)M) and inhibition at high doses (3 X 10(-7) - 3 X 10(-6)M). Stimulation of transport was also observed with intraluminal angiotensin but only at a dose of 10(-9)M. Transepithelial potential difference was calculated from the steady-state chloride distribution; no significant change was observed at low (10(-11)M) or high (10(-6)M) concentrations and a direct action on sodium transport is postulated. This biphasic effect is discussed in relation to the responses of the intact kidney to intra-renal infusion of angiotensin, and to the control of tubulo-glomerular feed-back.
346 citations
TL;DR: A definite relationship is apparent between the ratios of cholesterol: phospholipid, the ratio of polyunsaturated: saturated phospholIPid-bound fatty acids, and the susceptibility of the spermatozoa to cold-shock.
259 citations
TL;DR: Using the abdominal constriction response as the criterion for analgesia, mice tested immediately after a period of footshock showed a significant analgesic response compared with non-footshocked controls, concluding that footshock induced analgesia in the mouse is due to the release of endogenous opioid peptides.
228 citations
TL;DR: A new nonlinear regression program FUNFIT, written for interactive time sharing, is presented which should be more reliable than programs based on the Gauss-Newton or other related gradient methods.
Abstract: The problems of curve fitting and modeling in pharmacokinetics are discussed. A new nonlinear regression program FUNFIT, written for interactive time sharing, is presented which should be more reliable than programs based on the Gauss-Newton or other related gradient methods. The new program and the well-established program NONLIN were tested on two linear models using human plasma drug level data. FUNFIT found a substantially better solution than NONLIN in the majority of the cases.
218 citations
TL;DR: In this article, a transformation of the species conservation equations is used to analyse experimental data on laminar diffusion flames to obtain chemical reaction rates, using only composition and temperature measurements, the velocity field not being required.
213 citations
TL;DR: In this paper, all three components of the dissipation rate of the fluctuating temperature φ are measured simultaneously in the inner region of a fully developed turbulent boundary layer at a moderate Reynolds number.
Abstract: All three components of the dissipation rate of the fluctuating temperature ϑ are measured simultaneously in the inner region of a fully developed turbulent boundary layer at a moderate Reynolds number. Measurements are made with a probe of four cold wires consisting of two closely spaced parallel vertical wires mounted a small distance upstream of two closely spaced parallel horizontal wires. In the inner region of the layer, local isotropy is not closely approximated (∂ϑ/∂z)2〉 (∂ϑ/∂y)2〉 (∂ϑ/∂x)2. The spectral density of the sum χ[= (∂ϑ/∂x)2+(∂ϑ/∂y)2+ (∂ϑ/∂z)2] is similar in shape to that of (∂ϑ/∂y)2 or (∂ϑ/∂z)2 but not as rich in high frequency content as that of (∂ϑ/∂x)2. The probability density of χ has a lower skewness and flatness factor and is more closely log‐normal than those of the individual components. This is true regardless of whether χ and its components are unaveraged or locally averaged over a linear dimension r. When averaging is applied, departures from log‐normality are diminished but ...
154 citations
TL;DR: The conclusion was reached that the reduction with age in B-cell as well as T-cell function is due to a qualitative rather than a quantitative defect in lymphocytes themselves.
TL;DR: It is suggested that the existence of the two populations is a result of micro-evolutionary changes within F. roseum ‘Graminearum’.
Abstract: Two populations, designated Group 1 and Group 2, have previously been distinguished within Fusarium roseum ‘Graminearum’ based on the inability or ability of cultures to form perithecia, respectively Further evidence is presented to support this proposal Group 1 differed from Group 2 in colony morphology and growth, conidial dimensions and septation and conidial production when incubated under standard conditions Colony diameters in Group 1 on PDA were within the range 39–51 cm whereas in Group 2 they were 47–61 cm These ranges were based on a series of experiments In any one experiment the range of colony diameters of members of Group 1 was always distinct from that of Group 2 Although single spore cultures of Group 2 formed perithecia readily on a variety of substrates at different temperatures, cultures of Group 1 did not Members of Group 1 are probably heterothallic and/or poorly fertile, or infertile It is suggested that the existence of the two populations is a result of micro-evolutionary changes within F roseum ‘Graminearum’
TL;DR: The solar absorptance of a single ideal film on an idealized metallic substrate has been calculated as a function of its optical constants to determine the optimum parameters for selective absorber applications.
Abstract: The solar absorptance of a single ideal film on an idealized metallic substrate has been calculated as a function of its optical constants to determine the optimum parameters for selective absorber applications. High normal solar absorptances (>0.9) are possible for single uniform interference films if n < 1.5 and 0.2 < k < 0.8, values that are achievable using cermet materials. Grading the refractive index of single interference films improves the absorptance, with optimum results given by a uniformly increasing dielectric constant through the layer. With such a linear grading to air, normal solar absorptances of greater than 0.9 can be achieved for n < 1.5 and 0.1 < k < 5. Grading an absorbing material with a dielectric also improves the performance of the absorbing material. For bulk films, the optimum profile with minimum material is one where the dielectric constant increases slowly at the surface of the film.
TL;DR: The ultrastructure changes observed depended not only on the magnitude of the chlorophyll increase but also on the architecture of thechloroplast, including the number of thylakoids per chloroplast.
Abstract: The photosynthetic pigments of 17 species of unicellular marine algae grown in white and blue-green light were examined. Blue-green light (400 μW·cm−2; 12:12 LD cycle) caused major chlorophyll increases (55–146%) in five diatoms, one dinoflagellate and one cryptomonad; minor chlorophyll increases (17–39%) in two diatoms, two dinoflagellates, one prymnesiophyte (haptophyte), one chrysophyte and one chlorophyte; and no chlorophyll increase in two diatoms and one pyrmnesiophyte (haptophyte). The relative proportions of major chlorophylls and carotenoids did not change, but in six of eight species tested small increases in the concentration of chlorophyll c occurred. Blue-green light caused a small increase in the concentration of phycoerythrin relative to chlorophyll a in the cryptomonad. A larger number of thylakoids per chloroplast were observed in six species grown in blue-green light compared to white light controls. The ultrastructure changes observed depended not only on the magnitude of the chlorophyll increase but also on the architecture of the chloroplast.
TL;DR: In this paper, a rigorous formulism of Chen, which describes the diffraction by perfectlyconducting inductive grids, is used to prove several general properties of grids, including the relevant form of the Reciprocity Theorem.
Abstract: A brief description is given of the rigorous formulism of Chen, which describes the diffraction by perfectly-conducting inductive grids. The formulism is used to prove several general properties of grids, including the relevant form of the Reciprocity Theorem. The theory is used to investigate the equivalent circuit model proposed by other authors for thin grids, and also to derive a monomodal model of the type first proposed by Chen. The latter model is shown to be useful even in the region where more than one spectral order propagates.
TL;DR: Social surveys have established dose–response relationships between aircraft noise and annoyance, with a number of psychological symptoms being positively related to annoyance, and evidence that exposure to aircraft noise is associated with higher psychiatric hospital admission rates is mixed.
TL;DR: In this paper, the authors assume that the basic units of flow are elastic flocs which are slightly deformed during collisions because of the stretching of the particle bonds within a floc by a few tenths of a nanometer.
Abstract: The observed energy dissipation in coagulated sols subjected to a shear flow can be explained by assuming that the basic units of flow are elastic flocs which are slightly deformed during collisions because of the stretching of the particle bonds within a floc by a few tenths of a nanometer. Liquid inside perforated structures is generally considered immobile, but during the deformation of the flocs some internal liquid movement occurs. Although the amount of internal liquid movement is rather small, of the order of 1%, it is sufficient to account for the observed energy dissipation.
TL;DR: Six experiments reported here confirmed the prediction that both repulsion (direct) and attraction (indirect) tilt illusions occur in the oblique meridian, and suggested the mechanisms of the illusion and aftereffect are the same.
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TL;DR: This research states that based on information in cat, guinea pig and man on the precise orientation of the semicircular canals, a more realistic specification of the forces acting on the cupulae during any head rotation is possible.
Abstract: Formulation of semicircular canal transfer functions have to date been restricted to idealized cases. Recent information in cat, guinea pig and man on the precise orientation of the semicircular canals allows a more realistic specification of the forces acting on the cupulae during any head rotation.This research was supported by grants from the National Health and Medical Research Council of Australia, the US Public Health Service Grant NS-06658, and NASA. Computing Assistance was obtained from the Health Sciences Computing Facility, UCLA, sponsored by NIH Special Research Resources Grant RR-3.
TL;DR: In this article, the authors propose a 2.0-approximation of the 2.3.0 algorithm, i.e., 2.4.0.1.
TL;DR: There is an urgent need to create valid research tools to support the development and implementation of the health–promoting school model, which offers a comprehensive, systematic approach to health promotion in the school setting.
TL;DR: The strong cross-linking of lipid bilayers suggests a role for basic protein in myelin, raising the possibility that the protein is instrumental in collapsing the oligodendrocyte cell membrane and thus initiating myelin formation.
Journal Article•
TL;DR: A study has been made of the formation and regression of synapses formed by spinal nerves 16 and 17 in axolotl hind‐limb flexor muscles following the severing of nerve 16, using histological, ultrastructural and electrophysiological techniques.
TL;DR: It is concluded that the contralateral labyrinth, acting via the vestibular brain stem commissural pathway, not only exerts a powerful effect on the resting activity of brain stem canal Vestibular neurons, but also on their response to acceleration.
TL;DR: The ultrastructure of four species of the calcareous, siphonaceous alga Halimeda (H. cylindracea Decaisne, H. discoidea DECaisne and H. macroloba DECISNE) has been studied in this article.
Abstract: The ultrastructure of 4 species of the calcareous, siphonaceous alga Halimeda (H. cylindracea Decaisne, H. discoidea Decaisne, H. macroloba Decaisne and H. tuna (Ellis & Solander) Lamour) has been studied, and the observed changes during growth and development are related to changes in the degree of calcification. A distinct gradient in the types and quantities of cell organelles exists in a growing apical filament. As these filaments grow, branch, and eventually develop into a mature segment, changes in the organization of organelles such as mitochondria and chloroplasts are observed. Calcification begins when the chloroplasts reach structural maturity and when the peripheral utricles adhere (fuse). This adhesion of the peripheral utricles isolates the intercellular space (ICS) in which calcification occurs from the external seawater. Calcification begins in the outermost (pilose) cell wall layer of the walls facing into the ICS. The cell walls at the thallus exterior undergo extensive changes after utricular fusion; the pilose layer is lost, the cuticles of adjacent utricles fuse forming a ridge at their junction, and multiple cuticles are formed.
The aragonite (CaCO3) crystals which are initially precipitated within the pilose wall layer, rapidly increase in size and number, eventually filling much of the ICS. Only the initial nucleation of aragonite is associated with the pilose wall layer, the later precipitation of aragonite is totally independent of the pilose layer. In older segments secondary deposition of CaCO3 also occurs around existing aragonite needles.
TL;DR: In this paper, an alternative approach from the traditional Gumbel method to the estimation of extreme mean wind speeds was examined, based on Rice's upcrossing rate expression and only requires a statistical description of the parent population.
TL;DR: In this paper, it is argued that the commenda embodied borrowings from several sources in different proportions and that this was entirely natural since the peculiar features of the medieval commenda were developed by the commercial community itself during the early Middle Ages.
Abstract: ULTIMATELY the origins of the medieval commenda contract are unknowable simply because the contract was the product of an amalgamation of many different raditions. That which follows does not pretend to offer conclusive evidence for the derivation of the commenda from any other single contract. Rather, its intent is to show that the commenda embodied borrowings from several sources in different proportions and that this was entirely natural since the peculiar features of the commenda were developed by the commercial community itself during the early Middle Ages. Indeed, the commenda would be expected to have embodied borrowings from elsewhere since the commercial community was surely the most pragmatic and eclectic of all segments of medieval society. Yet even if the commenda comprised an amalgam of borrowings from several different sources, the extent of borrowing from each of the various sources differed. It is a reinterpretation of the strength of the various influences and a suggestion for a revised synthesis which is offered here. In the course of the last decade, Professor Udovitch has argued forcefully and repeatedly that the source most likely to have contributed to the peculiar characteristics of the commenda was the Muslim qirad contract. He has argued this thesis in three successive works: "At the Origins of the Western Commenda: Islam, Israel, Byzantium?" SPECULUM 37 (1962), 198-207; Partnership and Profit in Early Medieval Islamic Trade (Princeton, 1970), p. 172; and "Commercial Techniques in Early Medieval Islamic Trade," in D. S. Richards, ed., Islam and the Trade of Asia: A Colloquium, Papers on Islamic History 2 (Oxford/Philadelphia, 1970), p. 48. However, in spite of the forcefulness of his arguments and the indisputably close similarity of the qirad to the commenda, historians of medieval economic history remained skeptical. For example, on page 76 of his attractive little book The Commercial Revolution of the Middle Ages, 950-1350,1 Professor Lopez left the question open. He simply said that Islam and Byzantium seem to have the best claims as possible sources for the commenda. By this he alluded to the Byzantine chreokoin5nia contract as well as to the qiraid. In fact, the influences on the development of the commenda were even more complex than this. Both the Jewish 'isqa contract and the Roman societas have good claims to be important sources of the principles and characteristics of the commenda. The possible influence of these last two contracts on the commenda has been underestimated by most historians. A contract in which one party invested his labor and the other invested his capital was an eminently practical means of financing commerce. Consequently, it is not in the least surprising that contracts similar to the commenda should have been used previously by other civilizations. The Babylonian
TL;DR: The findings suggest that conduction is abnormal in at least some surviving nerve fibres in patients who developed a peripheral neuropathy 10 days to 3 weeks after ingestion of a single dose of arsenic.
TL;DR: The effects of prolonged strenous exercise on the plasma concentrations of sodium, potassium, calcium, chloride, bicarbonate, phosphate, albumin, cholesterol, glucose, creatinine, bilirubin, alkaline phosphatase, creatine phosphokinase, lactic dehydrogenase and asparate amino transferase were studied in a group of 26 horses competing in an endurance ride.
Abstract: The effects of prolonged strenous exercise on the plasma concentrations of sodium, potassium, calcium, chloride, bicarbonate, phosphate, albumin, cholesterol, glucose, creatinine, bilirubin, alkaline phosphatase, creatine phosphokinase, lactic dehydrogenase and asparate amino transferase were studied in a group of 26 horses competing in an endurance ride. There were significant changes in most parameters, when control values were compared with those taken immediately after the ride. There was also a significant correlation between several biochemical parameters and heart rate taken 30 minutes after the ride. When faster and slower horses were compared, significant differences were found only in phosphate and glucose values.