Showing papers by "University of St Andrews published in 1979"
TL;DR: Using a stereoscopic matching task, the second experiment showed that the perceived depth from parallax transformations is in close agreement with the degree of relative image displacement, as well as producing a compelling impression of three-dimensionality not unlike that found with random-dot stereograms.
Abstract: The perspective transformations of the retinal image, produced by either the movement of an observer or the movement of objects in the visual world, were found to produce a reliable, consistent, and unambiguous impression of relative depth in the absence of all other cues to depth and distance. The stimulus displays consisted of computer-generated random-dot patterns that could be transformed by each movement of the observer or the display oscilloscope to simulate the relative movement information produced by a three-dimensional surface. Using a stereoscopic matching task, the second experiment showed that the perceived depth from parallax transformations is in close agreement with the degree of relative image displacement, as well as producing a compelling impression of three-dimensionality not unlike that found with random-dot stereograms.
673 citations
TL;DR: In this article, a magnetohydrodynamic stability analysis of a model loop by the energy method suggests that the main reason for stability is the fact that the ends of the loop are anchored in the dense photosphere.
Abstract: Solar coronal loops are observed to be remarkably stable structures. A magnetohydrodynamic stability analysis of a model loop by the energy method suggests that the main reason for stability is the fact that the ends of the loop are anchored in the dense photosphere. In addition to such line-tying, the effect of a radial pressure gradient is incorporated in the analysis.
378 citations
TL;DR: In this article, a number of instabilities can occur because of the coexistence of positive and negative energy waves, or because of damping of negative energy wave; some particular examples are discussed to show how appreciation of this role allows one to predict the existence of instability before doing any detailed analysis and to gain insight into the instability mechanism.
Abstract: Parallel flows with step function velocity and density profiles can support waves which have negative energy, in the sense that exciting them lowers the total energy of the system. A number of instabilities can occur because of the coexistence of positive and negative energy waves, or because of the damping of negative energy waves; some particular examples are discussed to show how appreciation of this role of negative energy waves allows one to predict the existence of instability before doing any detailed analysis, and to gain insight into the instability mechanism.
281 citations
TL;DR: In this paper, consistent patterns of errors are found in estimations of distances and angles along urban routes, even among subjects who know the areas well, and these patterns can be used to discover the organizati...
Abstract: Consistent patterns of errors are found in estimations of distances and angles along urban routes, even among subjects who know the areas well. These patterns can be used to discover the organizati...
254 citations
TL;DR: Chloroplast movement in H. stipulacea is shown to be complex and to reduce photoinhibition, whilst leaf senescence in P. oceanica is suggested as a cause of marked seasonal variation in its photosynthetic rate, with high rates in spring and low rates in summer.
151 citations
143 citations
TL;DR: In this paper, the probability distribution of fluctuations in the intensity of laser light propagating through atmospheric turbulence is reasonably well described by K distributions in the intermediate range of propagation path lengths, L ≃ 600 m, β 0≃1-2, where the mean square fluctuation can be as high as five.
Abstract: Experimental results are presented which suggest that the probability distribution of fluctuations in the intensity of laser light propagating through atmospheric turbulence are reasonably well described by K distributions in the intermediate range of propagation path lengths, L ≃ 600 m, β0≃1–2, where the mean square fluctuation 〈I2〉 /〈I〉2 can be as high as five.
136 citations
TL;DR: In this article, the authors show that the delay in nucleation of olivine in basaltic melts increases systematically with decreasing degree of supercooling, cooling rate, superheat, olivines content of the melt and with increasing melt viscosity.
Abstract: The delay in nucleation of olivine in basaltic melts increases systematically with decreasing degree of supercooling, cooling rate, superheat, olivine content of the melt and with increasing melt viscosity. These findings imply homogeneous nucleation of olivine in melts run in the Pt-wire loop sample container used. Unlike plagioclase nucleation, the appearance of the first olivine crystal in a melt is predictable (to within 0.1–1 h of the event). The ‘metastable region’ (i.e., the minimum degree of supercooling necessary for nucleation) is less than 13 ° C. The cause of the delay in nucleation is discussed in terms of the finite growth rate of embryos and the progressive polymerization of the melt with decreasing temperature and increasing time. At degrees of superheat <18 ° the melts are inferred to be more highly disordered than expected. Some implications of the results for petrology and experimental petrology are discussed, including the possibility that continuous zoning may develop under isothermal conditions due to the sluggish attainment of equilibrium of melt structure following a sudden change in temperature.
99 citations
TL;DR: In this article, the role of immiscibility in the formation of carbonatite magmas has been discussed, and it has been shown for the first time that it does occur between silicate and carbonate liquids of the compositions found in nature.
Abstract: THE existence of carbonatite magmas has been generally accepted1, but their origin remains uncertain. The more favoured petrogenetic models include: (1) direct partial melting of the upper mantle2–5; (2) fractional crystallisation of CO2-rich alkaline silicate magma6; and (3) separation of an immiscible carbonate melt from an initially homogeneous CO2-rich alkaline silicate magma7–10. Experiments have shown all of these processes to be feasible5–7, and each may generate the geochemical characteristics of carbonatite, such as enrichment in rare earths and other incompatible trace and minor elements11,12, and low 87Sr/86Sr ratios13. Here we discuss the role of immiscibility, and report new experimental data which demonstrate for the first time that liquid immiscibility does occur between silicate and carbonate liquids of the compositions found in nature.
84 citations
TL;DR: In this article, the spatial wave front characteristics of a laser were examined by two beam interference after amplitude division, and complex interference patterns were interpreted as due to a helical form of the phase front.
82 citations
TL;DR: Observations concerning the in situ determination of the protein composition of the two membranes of cultured renal (MDCK) epithelial cells shown to maintain morphological and functional features similar to an in vivo renal.
TL;DR: A study of lipid changes during the frozen storage of cod confirms that the major change is that of lipolysis, and sufficient oxidation takes place during cold storage to reduce the acceptability of the fish primarily through the production of hept-cis-4-enal.
Abstract: A study of lipid changes during the frozen storage of cod confirms that the major change is that of lipolysis. Oxidation is extremely slow and occurs primarily in the phospholipid fraction. Nevertheless, sufficient oxidation takes place during cold storage to reduce the acceptability of the fish primarily through the production of hept-cis-4-enal. The mechanism whereby hept-cis-4-enal occurs is discussed.
TL;DR: In this paper, the depth and diameters of 158 cryoconite holes were measured at ten positions in the ablation zone of Sermikavsak, West Greenland and the variations in depth were attributed to changes in the albedo and the bulk extinction coefficient of the surface ice layers on the glacier.
Abstract: The depths and diameters of 158 cryoconite holes were measured at ten positions in the ablation zone of Sermikavsak, West Greenland. It was found that the depths increased on going up the glacier in agreement with other measurements made earlier on polar glaciers. There was no significant correlation of depth with diameter. The relative importance of the combined short- and long-wavelength radiation balances and the transfer of heat by convectional mixing in water-filled holes is discussed. The variations in depth are attributed to changes in the albedo and the bulk extinction coefficient of the surface ice layers on the glacier.
TL;DR: The octanol/water partition coefficient alone is not sufficient for predicting the lethality of pyrethroids to salmon or lobster.
Abstract: (IR)-cis-permethrin, decamethrin, and NRDC 168S are extremely lethal to salmon and lobster. The increase in lethality relative to that of permethrin follows qualitatively the patterns established in toxicity studies with insects: (IR)-cis isomers are more lethal than (IR)-trans, and the presence of an αcyano group in the phenoxybenzyl moiety increases the lethality. The latter effect is very pronounced for lobsters. The octanol/water partition coefficient alone is not sufficient for predicting the lethality of pyrethroids to salmon or lobster.
TL;DR: A number of esters and other compounds containing a trans-1,4-substituted cyclohexane ring system have been prepared, and the liquid crystal thermal stabilities of these new mesogens are discussed in relation to those of their analogues containing the 1,4phenylene ring as discussed by the authors.
Abstract: A number of esters and other compounds containing a trans-1,4-substituted cyclohexane ring system-have been prepared, and the liquid crystal thermal stabilities of these new mesogens are discussed in relation to those of their analogues containing the 1,4-phenylene ring. The observed effects are discussed in terms of a possible thermal energy absorption by the cyclohexane ring in causing minor conformational changes. Other physical properties of these new mesogens are also discussed with particular reference to their potential in applications. In relation to electro-optical display devices, such properties as birefringence, dielectric anistropy, viscosity etc., are important parameters, and the new materials have been assessed in this context as possible additives to the 4-n-alkyl- and 4-n-alkyloxy-4′-cyanobiphenyls for producing a favorable combination of physical parameters. Also reported is a liquid crystal mixture which has a 100°C nematic range and which contains only materials which are ali...
TL;DR: In this article, a compact long-life CO 2 -N 2 -He-Xe laser has been developed to produce 4-8 W on any one of ten CO 2 00°-10°0 and 00°1-02°0 transitions, selected by the laser signature technique.
TL;DR: Electrophysiological observations have been made upon the cell body of an identified motoneurone of the cockroach, Periplaneta americana, and normal responses were compared with those observed after intracellular injection of citrate anions or when the preparation was bathed in solutions containing tetraethylammonium ions (TEA+).
Abstract: 1. Electrophysiological observations have been made upon the cell body of an identified motoneurone of the cockroach, Periplaneta americana. Normal responses were compared with those observed after intracellular injection of citrate anions or when the preparation was bathed in solutions containing tetraethylammonium ions (TEA+).
2. Normally when depolarized, the motoneurone soma gave a series of damped oscillations; the amplitude of these responses increased with increase in the applied current.
3. After citrate ions had been injected into the neurone soma, all-or-none action potentials were evoked by depolarization; such responses appeared about 5-10 min after the onset of citrate injection. Injection of EGTA produced similar effects. Citrate and EGTA probably produce their effect through a reduction in the intracellular free calcium concentration.
4. When preparations were bathed in saline solution containing 50 m M-TEA+, soma depolarization produced prolonged all-or-none action potentials (up to approximately 100 msec duration).
5. The action potentials produced by citrate injection or externally applied TEA+ appeared to have a similar ionic mechanism; they were not depressed by sodium-free solutions or by tetrodotoxin (4 × 10−6 M) but were reversibly blocked in saline solution containing 40 m M-manganous chloride.
6. The overshoot amplitude of action potentials recorded after injection of citrate anions or in solutions containing TEA+ showed a 22·5 mV change for a ten-fold change in the external calcium concentration.
7. Both intracellular citrate and external TEA+ caused a significant increase in the input resistance and membrane time constant of the motoneurone.
8. It is concluded that action potentials generated under various experimental conditions in the soma of this insect motoneurone map have differing ionic mechanisms.
TL;DR: In this paper, a measure of the agreement between two rankings of a set of objects is proposed, which not only gives an indication of the overall correspondence of the rankings, but also specifies the objects in each sequence which are contributing to the agreement.
Abstract: SUMMARY A measure of the agreement between two rankings of a set of objects is proposed. This measure not only gives an indication of the overall correspondence of the rankings, but also specifies the objects in each sequence which are contributing to the agreement. The null distribution of the measure is found to be related to a standard problem in combinatorics: given a random permutation of the first N integers, what is the distribution of the length of a longest monotone subsequence? Algorithms are described for obtaining the set of objects contributing to the measure of agreement. Several extensions are considered, in particular the problem of preserving tied ranks, and an application to classification studies is noted.
TL;DR: Because the dopamine-containing neurone in the right pedal ganglion is readily located in living preparations, it would appear to be a useful model for studying the cellular role of neuronal dopamine.
TL;DR: In this article, the authors propose that spicules are the direct result of a resonant buffeting of the sides of an intense (kilogauss) slender flux tube by turbulent granular motions.
Abstract: We propose that spicules are the direct result of a resonant buffeting of the sides of an intense (kilogauss) slender flux tube by turbulent granular motions. For a critical wavespeed, the granular motion drives a high-speed flow along the axis of the tube. We illustrate this effect by considering in detail a flux tube embedded in a uniform compressible atmosphere, thereby modelling the development of the ‘seedflow’ in the photosphere that eventually manifests itself in the chromosphere as the spicule.
TL;DR: The results suggest that the regulatory proteins can influence the kinetics of the ATPase and, furthermore, that they are involved in the acclimation of the actomyosin to different cell temperatures.
Abstract: Goldfish (Carassius auratus) were acclimated for 5 months at temperatures of either 2°C or 31°C. Natural actomyosin was prepared from white myotomal muscle and its Mg2+Ca2+ ATPase activity determined. Temperature acclimation results in adaptations in substrate turnover number and thermodynamic activation parameters of the ATPase. When assayed at 31°C the Mg2+Ca2+ ATPase of natural actomyosin was 4 times higher in 31°C than 2°C acclimated fish. Arrhenius plots of natural actomyosin ATPase from cold acclimated fish show a break in slope at 15–18°C. In contrast, the temperature dependence of warm acclimated actomyosin was linear. Activation enthalpy (ΔH
‡) of the ATPase, calculated over the range 0–16°C, was approximately 8,000 cal/mole lower in 2°C than 32°C acclimated fish. In contrast, desensitised actomyosins from which the calcium regulatory proteins have been removed show a linear temperature dependence in the range 0–32°C and have similar properties in 2°C and 31°C acclimated fish. Cross-hybridisation of regulatory proteins (tropomyosin-troponins complex) from cold-acclimated fish to desensitised actomyosin from warm-acclimated fish alters the ATPase towards that of cold-acclimated natural actomyosin and vice versa. The results suggest that the regulatory proteins can influence the kinetics of the ATPase and, furthermore, that they are involved in the acclimation of the actomyosin to different cell temperatures.
TL;DR: It appears that there is a threshold of absolute energy required to support the lecithotrophic larval strategy in nudibranchs, and that this is not attained by the smaller species, A. muricata, but by the larger species, O. proxima, which appears to have both reproductive strategies open to it.
Abstract: Onchidoris muricata (Muller) and Adalaria proxima (Alder and Hancock) are sympatric, potentially competing species of dorid nudibranchs, which preferentially graze the cheilostome polyzoan Electra pilosa (L.). O. muricata is small and lays small eggs which hatch as poorly-developed planktotrophic veliger larvae. A. proxima is larger and reproduces by means of larger eggs which hatch, as well-developed lecithotrophic larvae, that can metamorphose within approximately 24 h of release. A. proxima larvae can feed in the plankton, but do not require extrinsic nutrition to undergo complete development. Both species spawn in February–april, and have a strictly annual life-cycle. Comparisons of the calorific content of spawn have shown that A. proxima apportions a greater number of calories to reproduction, but that O. muricata makes a greater relative effort. A. proxima shown considerable individual variability in reproductive effort, which fails to correlate with, body size or rate of spawning. A more deterministic situation applies to O. muricata, because body size and fecundity follow an allometric relationship. It appears that there is a threshold of absolute energy required to support the lecithotrophic larval strategy in nudibranchs, and that this is not attained by the smaller species, O. muricata. A. proxima thus appears to have both reproductive strategies open to it, and to have adopted lecithotrophy in order to offset the unpredictability of energy available for reproduction.
TL;DR: In this paper, a method for comparing and correlating borehole sequences using information from one or more physical logs recorded from the boreholes is described, where constraints may be imposed on the comparison to allow the incorporation of relevant information, such as the presence of marker beds in the stratigraphic sequences.
Abstract: A method is described for comparing and correlating borehole sequences using information from one or more physical logs recorded from the boreholes. The method is illustrated by a small worked example. Ways are described whereby constraints may be imposed on the comparison to allow the incorporation of relevant information, such as the presence of marker beds in the stratigraphic sequences. An account is given of the comparison of three boreholes in the Lansing Group of Kansas, USA, and there is a short discussion on the effects of filtering, standardizing, and weighting the logs.
TL;DR: The guts of the teleosts Myoxocephalus scorpius, Pleuronectes platessa and Clupea harengus were examined using fluorescent histochemistry and the innervation compared to that in mammals and other lower vertebrates, finding green and yellow fast fading fluorescent nerves in the intestine.
Abstract: The guts of the teleosts Myoxocephalus scorpius, Pleuronectes platessa and Clupea harengus were examined using fluorescent histochemistry and the innervation compared to that in mammals and other lower vertebrates. In Myoxocephalus and Pleuronectes both green and yellow fast fading fluorescent nerves were found in the intestine. To test whether the yellow nerves might be serotonergic, an attempt was made to extract 5-HT from the intestine of these fish in a region where enterochromaffin cells were absent. Chromatography of extracts showed the presence of 5-HT, and, in Myoxocephalus, dopamine.
TL;DR: Gaskin, F., Cantor, C. R. & Shelanski, M. L. (1975) Ann.
Abstract: Gaskin, F., Cantor, C. R. & Shelanski, M. L. (1975) Ann. N. Y . Acod. Sci. 253, 133-146 Lowry, 0. H., Rosebrough, N. J., Farr, A. L. & Randall. R. J. (1951)J. Biol. Chem. 193,265-275 Maddy, A. H. & Spooner, R. 0. (1970) Vos Song. 18,34-41 Shapiro, A. L., Vinuela, E. & Maizel, J. V. (1967) Biochem. Biophvs. Res. Cornmitn. 28, 815-820 Strzinek, R. A,, Vela, G . R., Scholes, V. E. & Norton, S . J. (1970) Cancer Res. 30, 334-337 Thomas, J. 0. (1974) in Componioii / o Biochemistry ( B u l l , A. T . , Lagnado, J. R., Thomas, J. 0.
TL;DR: In this article, seasonal movements of the winter flounder, Pseudopleuronectes americanus (Walbaum), were examined in a protected inlet and an exposed cove in Conception Bay, Newfoundland.
Abstract: Seasonal movements of the winter flounder, Pseudopleuronectes americanus (Walbaum), were examined in a protected inlet and an exposed cove in Conception Bay, Newfoundland. Winter flounders remained at both sites except to feed in summer and to avoid extremes of turbulence and ice scouring from fall to spring. In general, winter flounders remain inshore in summer where water temperatures and food are suitable. With gonad ripening in the fall and early winter, they remain in, or move into, shallow water where they will spawn that winter (southern habitats) or spring (northern habitats). During winter in northern habitats, winter flounders will move to deeper water to avoid extremes of turbulence and ice scouring. The evidence indicates that there is no avoidance of cold temperatures in winter.
TL;DR: In this article, nine rare earths have been determined by Instrumental Neutron Activation Analysis (INAA) in syenites and related granitic rocks from the Nigerian younger granite (Mesozoic) Province.
Abstract: Nine rare earths have been determined by Instrumental Neutron Activation Analysis (INAA) in syenites and related granitic rocks from the Nigerian younger granite (Mesozoic) Province. The majority of the granites contain dispersed UNb and vein-controlled ZnSn mineralization. It is inferred from a study of the chondrite-normalized rare-earth patterns that europium depletion in alkaline and sub-alkaline mineralized granites appears to be not just related to magmatic processes but also to hydrothermal changes induced during sub-solidus recrystallization.
TL;DR: In this paper, the ceramique de l'Armada trouvee dans different epaves of l'armada (Girona, S. Maria de la Rosa and Trinidad Valencera) was analyzed.
Abstract: French Summary
La ceramique de l'Armada
COLIN J. M. MARTIN
La classification et l'analyse dc la ceramiquc trouvee dans differentes epaves de l'Armada (Girona, S. Maria de la Rosa et Trinidad Valencera) mettent en evidcnce des centres de fabrication (a Seville, Merida, Lishonne, Saint-Sebostien) de divers types de poterie iberique dont la forme avait une relation avec le contenu. On releve aussi differentes methodes utilisees pour fabriquer la cemique vernissee ou non. Trois tessons vernisses a l'aide d'etain et six non vernisses, de couleur rouge, ont ete analyses sous l'aspect petropaphique. On compare la classification de Goggin et les collections de Langouez de Grande-Bretagne. Les archives de Simanca sont utilisees pour denommer la vaisselle decouverte dans cette epave, et qui etait officiellement en usage sur l'Armada.
TL;DR: Evidence has been obtained that muscle fibre number remained unchanged following immobilisation, and mechanisms for the transformation of muscle fibre types and the influence of muscle length on the properties of immobilised muscle are discussed.
Abstract: The knee joints of one hind limb of male Wistar rats (250–300 g) were immobilised in a plaster cast for up to 3 weeks with the limb in either the fully extended or flexed position Serial frozen sections ofvastus intermedius muscle were stained histochemically for myosin ATPase, succinic dehydrogenase, phosphorylase and capillaries. Muscle fibres were classified as either slow twitch oxidative (SO), fast twitch oxidative glycolytic (FOG) or fast twitch glycolytic (FG). Fibre area of SO fibres (3019 μ2) decreased by 50% following 3 weeks' immobilisation in the stretched (1532 μ2) and shortened (1517 μ2) positions. Atrophy of FOG fibres (2456 μ2) was greater in muscles immobilised in the stretched (750 μ2) than shortened (1185 μ2) positions. Evidence has been obtained that muscle fibre number remained unchanged following immobilisation. Control muscles contained 70.4% SO fibres, 29.6% FOG fibres and >0.5% FG fibres. Immobilisation produced an increased proportion of high myosin ATPase staining fibres. The percentage occurrence of FOG fibres increased to 65% and 83% respectively, in muscles immobilised for 3 weeks in the stretched and shortened positions. Mechanisms for the transformation of muscle fibre types and the influence of muscle length on the properties of immobilised muscle are discussed.
TL;DR: In this article, the temperature distribution and the rate of removal of heat by a coolant are predicted for the process of solidification of a liquid about a cold, isothermal pipe.