Showing papers by "University of Bath published in 1985"
TL;DR: The topics and examples discussed in this paper are intended to promote the understanding and extend the practicability of the spline smoothing methodology.
Abstract: Non-parametric regression using cubic splines is an attractive, flexible and widely-applicable approach to curve estimation. Although the basic idea was formulated many years ago, the method is not as widely known or adopted as perhaps it should be. The topics and examples discussed in this paper are intended to promote the understanding and extend the practicability of the spline smoothing methodology. Particular subjects covered include the basic principles of the method; the relation with moving average and other smoothing methods; the automatic choice of the amount of smoothing; and the use of residuals for diagnostic checking and model adaptation. The question of providing inference regions for curves-and for relevant properties of curves--is approached via a finite-dimensional Bayesian formulation.
1,018 citations
TL;DR: In this paper, a review of the generation, occurrence and action of singlet oxygen in plant tissue is presented, focusing on its formation from triplet sensitizers and its reactivity with molecules of biological importance such as lipids and amino acids.
336 citations
TL;DR: The 3 He 4 He ratio for radiogenic He is shown to be primarily determined by the abundance of Li and neutron-absorbing elements in the host formations and is almost independent of the radioelement abundance as mentioned in this paper.
305 citations
TL;DR: In this paper, the tensile strength and Young's modulus, work of fracture determined by Charpy impact and inter-laminar shear strength have been measured as a function of fiber volume fraction.
Abstract: Raw jute fibre has been incorporated in a polyester resin matrix to form uniaxially reinforced composites containing up to 60 vol% fibre. The tensile strength and Young's modulus, work of fracture determined by Charpy impact and inter-laminar shear strength have been measured as a function of fibre volume fraction. These properties all follow a Rule of Mixtures relationship with the volume fraction of jute. Derived fibre strength and Young's modulus were calculated as 442 MN m−2 and 55.5 GN m−2 respectively. Polyester resin forms an intimate bond with jute fibres up to a volume fraction of 0.6, above which the quantity of resin is insufficient to wet fibres completely. At this volume fraction the Young's modulus of the composite is approximately 35 GN m−2, the tensile strength is 250 MN m−2, the work of fracture is 22 kJ m−2 and the inter-laminar shear strength is 24 MN m−2. The properties of jute and glass fibres are compared, and on a weight and cost basis jute fibres are seen in many respects to be superior to glass fibres as a composite reinforcement.
265 citations
TL;DR: In this paper, modified equinoctial elements are introduced which are suitable for perturbation analysis of all kinds of orbit and Equations of motion in Lagrangian and Gaussian forms are derived.
Abstract: Modified equinoctial elements are introduced which are suitable for perturbation analysis of all kinds of orbit. Equations of motion in Lagrangian and Gaussian forms are derived. Identities connecting the partial derivatives of the disturbing function with respect to equinoctial elements are established. Numerical comparisons of the evolution of a perturbed, highly eccentric, elliptic orbit analysed in equinoctial elements and by Cowell's method show satisfactory agreement.
247 citations
TL;DR: Evidence is provided that oxygen free radicals are produced and may be important in the genesis of reperfusion induced arrhythmias in the isolated rat heart.
237 citations
TL;DR: The tandem scanning reflected light microscope has the property of being able to obtain information from ‘inside’ solid objects by taking a thin optical section at the focal plane of the objective lens.
Abstract: SUMMARY
The tandem scanning reflected light microscope has the property of being able to obtain information from ‘inside’ solid objects by taking a thin optical section at the focal plane of the objective lens. This plane can be focused up and down through the specimen.
We describe an unbiased 3-D counting rule for the TSRLM, which is applied to the estimation of osteocyte lacunar density in whole bone. This is shown to be an extremely efficient way of making such an estimate. Further possibilities for the application of the microscope in the field of stereology are discussed.
150 citations
107 citations
TL;DR: In this paper, the fifth-instar larvae of Manduca sexta were reared on an artificial diet at 25°C and daily measurement of the wet and dry weights of insects, food eaten and faeces produced, allowed the construction of detailed budgets for food and water economy.
103 citations
TL;DR: In this article, the infrared spectrum was used to study the vibration of CO adsorbed on small, silica-supported platinum particles, and three bands can be detected on each of the different samples.
99 citations
TL;DR: In this article, the Morse index of the critical point of a convex Hamiltonian system was shown to be the minimum period of the corresponding T/k-periodic solution.
Abstract: Clarke has shown that the problem of findingT-periodic solutions for a convex Hamiltonian system is equivalent to the problem of finding critical points to a certain functional, dual to the classical action functional. In this paper, we relate the Morse index of the critical point to the minimal period of the correspondingT-periodic solution. In particular, we show that if the critical point is obtained by the Ambrosetti-Rabinowitz mountain-pass theorem the corresponding solution has minimal periodT, that is, it cannot beT/k-periodic withk integer,k≧2. As a consequence, we prove that if the Hamiltonian is flat near an equilibrium and superquadratic near infinity, then for anyT>0, the corresponding Hamiltonian system has a periodic solution with minimal periodT.
TL;DR: In this article, a hydrochemical, radiochemical and dissolved gas study was undertaken to establish the flow pattern in the Innviertel and its relationship to groundwaters in deeper formations in the Molasse basin.
TL;DR: In this paper, the authors considered a model medium in which only the density varies and established bounds of Hashin-Shtrikman type for the eigenvalues of its combined transform, when the transform variables are real.
TL;DR: This article examined the hypothesis that industrial purchasers' assessments of their suppliers are not based on views of suppliers' technical and commercial skills in isolation, but are closely associated with their assessment of suppliers" skills in developing a relationship with them.
Abstract: This article examines the hypothesis that industrial purchasers' assessments of their suppliers are not based on views of suppliers' technical and commercial skills in isolation. Instead they are closely associated with their assessment of suppliers' skills in developing a relationship with them.
TL;DR: The spatial development, in beech logs exposed to air-borne and soil-borne inoculum, of mature fungal communities containing mutually or unilaterally exclusive mycelia of decay species is described and related to the ecological strategies and interaction of participant individuals.
Abstract: Summary
The spatial development, in beech logs exposed to air-borne and soil-borne inoculum, of mature fungal communities containing mutually or unilaterally exclusive mycelia of decay species is described and related to the ecological strategies and interaction of participant individuals. A combative heirarchy is recognized between (i) ruderal and/or stress-tolerant individuals which are spatially dominant early on and then decline, through (ii) air-borne combative individuals of decay fungi, such as Coriolus versicolor (L. ex Fr.) Quel. and Stereum hirsutum (Willd. ex Fr.) S. F. Gray, which establish mutually exclusive decay columns expanding away from the aerial cut surface, and culminating with (iii) highly combative individuals of mycelial cord-formers such as Phallus impudicus (L.) Pers. and Phanerochaete velutina (DC ex Pers.) Parmasto, which invade slowly from the base, ultimately occuping large volumes of wood, causing intense decay, and replacing many of the pioneers.
Addition of basidiospore suspensions of Bjerkandera adusta (Willd. ex Fr.) Karst., C, versicolor, Hypholoma fasciculare (Huds. ex Fr.) Kummer or S. hirsutum to the aerial cut surface appeared to affect community dynamics and functioning markedly. Development of decay columns by air-borne fungi was inhibited and associated with enhanced vertical penetration by basally-colonizing fungi, and persistence of the relatively non-combative species Xylaria hypoxylon (L. ex Hooker) Greville and Armillaria bulbosa. (Barla) Kile & Watling. Re-cutting of the aerial cut surface resulted in community development patterns somewhat intermediate between those in naturally colonized and inoculated logs.
TL;DR: Yeasts from chilled foods were killed in illuminated solutions of Rose Bengal but a light intensity of 315 microE/m2/s was needed for a death rate comparable with that of bacteria, and Singlet oxygen was identified as the lethal agent.
Abstract: Rose Bengal was cytotoxic to the following bacteria at the concentrations given in parentheses (highest concentrations of dye in mol/l at which growth occurred on nutrient medium): Brochothrix thermosphacta and Deinococcus radiodurans (1 X 10(-6) or less); Streptococcus, Micrococcus, Staphylococcus, Bacillus, Arthrobacter and Kurthia spp. (1 X 10(-5)-1 X 10(-4], and Pseudomonas spp. and Enterobacteriaceae (5 X 10(-3)-1 X 10(-2) or greater). These organisms were killed rapidly when suspended in illuminated (170 microE/m2/s) solutions of Rose Bengal (1 X 10(-4) mol/l) providing oxygen was present. Singlet oxygen was identified as the lethal agent, because the rate of killing was increased by dissolving the dye in deuterium oxide while the organism were protected against photoinactivation by L-histidine or crocetin. Yeasts from chilled foods were killed in illuminated solutions of Rose Bengal but a light intensity of 315 microE/m2/s was needed for a death rate comparable with that of bacteria. The yeasts present in a range of chilled meat and dairy products failed to form colonies on Rose Bengal (5 X 10(-5) mol/l) media exposed continuously to modest illumination (55-80 microE/m2/s).
TL;DR: Evidence for the generation of singlet molecular oxygen by hypericin is provided by the monitoring of oxygen consumption during the photosensitized oxidation of imidazole, and the photodynamic action ofhypericin on pea leaf discs results in the promotion of photo-oxidative damage, measured by pigment loss and ethane production.
Abstract: . Hypericin, a photodynamic pigment, occurring in members of the Hypericaceae, can induce photosensitivity in grazing animals. The pigment has been isolated from the glandular trichomes located on the calyx of Hypericum hirsulum. Hypericin is shown to be capable of sensitizing the photo-oxidation of methyl linolenate. This activity is reduced in the presence of crocin, a carotenoid. Evidence for the generation of singlet molecular oxygen by hypericin is provided by the monitoring of oxygen consumption during the photosensitized oxidation of imidazole. Rates of oxygen consumption were modified by deuterium oxide and sodium azide. The photodynamic action of hypericin on pea leaf discs results in the promotion of photo-oxidative damage, measured by pigment loss and ethane production. These results are discussed in relation to the possible function of hypericin within the plant and the role of photo-dynamic reactions in nature.
TL;DR: Evidence was obtained that small volumes of discoloured, but not strongly decayed wood, sometimes contained large numbers of mutually antagonistic individuals of the decay species B. adusta, C. hirsutum and C. Gray.
Abstract: More than 450 beech (Fagus sylvatica L.) logs, 10 to 20 cm in diameter and 30 to 40 cm long, were cut from freshly felled trees and placed upright 1 m apart with their bases buried up to 10 cm deep in the ground in a plot of about 600 m2 in a mixed deciduous woodland in the Forest of Dean, Gloucestershire, UK. Fungal colonization via the aerial and buried cut surfaces was studied - in some cases following inoculation of basidiospores - using a combination of direct and indirect techniques. A wide variety of ascomycetes, basidiomycetes and fungi imperfecti were identified, by direct observation or following direct incubation of wood samples, from the vicinity of the aerial cut surface within the first six months after cutting. Some such as Coriolus versicolor (L. ex Fr.) Quel. subsequently increased in occurrence, whereas others, including Chondrostereum purpureum (Fr.) Pouz. declined. Isolation onto malt agar from thin sections of wood revealed the presence of some fungi, notably a Fusarium sp., not detected by direct means. In addition, homokaryons of the basidiomycetes Bjerkandera adusta (Willd, ex Fr.) Karst. and C. versicolor were isolated from near the aerial cut surface up to two years after cutting, and, lower down, mostly up until six months after cutting (thereafter heterokaryons predominated). Moreover, evidence was obtained that small volumes of discoloured, but not strongly decayed wood, sometimes contained large numbers of mutually antagonistic individuals (up to 30 per cm3 ) of the decay species B. adusta, C. versicolor and Stereum hirsutum (Willd. ex Fr.) S. F. Gray. Vertical penetration from the aerial cut surface showed a marked lag phase, such that for the first six weeks after cutting, overt colonization was restricted to about 3 mm depth. Thereafter the depth occupied increased rapidly.
TL;DR: For chronically exposed caterpillars, none of the three usual indices of food conversion efficiency varied significantly with temperature between 20 and 35°C, which implies that the effects of temperature on metabolic costs are closely matched to food consumption.
TL;DR: In this paper, a variety of chemical and physical techniques have been employed to investigate the nickel-catalyzed reaction between CO and H2 and the accumulated evidence suggests that CH4 is produced by the stepwise addition of H2 to surface carbon, which is formed by dissociative adsorption of CO.
TL;DR: It is in the context of an alleged requirement to reduce numbers waiting that the proposal to offer a price subsidy for private medical care is appraised and such a policy is compared with that of direct expansion of expenditure on the NHS.
TL;DR: In this paper, the ion hopping rate values have been confirmed by mechanical relaxation measurements at two frequencies, 1.25 and 10 MHz, and the anomalously high conductivity prefactor, 6.3 × 10 5 ohm −1 cm −1 K, is associated with a large entropy, S, of activation.
Abstract: Measurements of the a.c. conductivity of AgIAg 2 MoO 4 glass over the temperature range − 84 to − 154°C have enabled d.c. conductivities and ion hopping rates to be obtained. The ion hopping rate values have been confirmed by mechanical relaxation measurements at two frequencies, 1.25 and 10 MHz. The anomalously high conductivity prefactor, 6.3 × 10 5 ohm −1 cm −1 K, is associated with a large entropy, S , of activation. A simple relationship between S and activator energy, E , proposed by Dienes, is shown to hold for a range of glassy Ag + conductors whereas the Wert and Zener expression seriously underestimates S , as shown by shear wave velocity and thermal expansion measurements.
TL;DR: A spectral analysis method that is insensitive to system gain calibration is developed that retrieves information from the signals that is well below the usual power spectrum point, thus effectively widening the system bandwidth, and can discriminate between the signals returned from six sea-bed types.
Abstract: Direct sampling of the sea bed is not always feasible and can be unreliable because the samples obtained may not be representative. An alternative approach is to classify the superficial sea bed using the backscattered signal from side-scan sonars. The usual paper display contains less information than the signal creating it, because of its low dynamic range, and interpretation of sediment types is often difficult. There are also problems with statistical analysis of the signals1. The usual methods of pattern recognition cannot resolve small-scale features in otherwise homogeneous regions2 and, although the backscattering strength is a useful quantity, meaningful numerical values can be obtained only with a calibrated system3. To overcome these shortcomings we have now developed a spectral analysis method that is insensitive to system gain calibration. The method retrieves information from the signals that is well below the usual power spectrum point, thus effectively widening the system bandwidth, and can discriminate between the signals returned from six sea-bed types.
TL;DR: In this article, the bifurcation of capillary-gravity waves is analyzed when the surface tension is close to or equal to a value where the eigenspace of the critical phase speed has multiplicity two and the existence and multiplicity of solutions is seen, via the implicit function theorem, to be a special case of the secondary bifurbation phenomena, which occur when a double eigenvalue splits, under perturbation, into two simple eigenvalues in the presence of a symmetry in the problem.
Abstract: The bifurcation and secondary bifurcation of capillary-gravity waves is analysed when the surface tension is close to or equal to a value where the eigenspace of the critical phase speed has multiplicity two. The existence and multiplicity of solutions is seen, via the implicit function theorem, to be a special case of the secondary bifurcation phenomena, which occur when a double eigenvalue splits, under perturbation, into two simple eigenvalues in the presence of a symmetry in the problem.
TL;DR: In this paper, the authors compared the Monte Carlo model with the simplified Monte Carlo method of Love et al. (1977) for the X-ray distribution of aluminium, gold and carbon.
Abstract: X-ray distributions in aluminium, gold and carbon have been measured using the tracer technique. The results have been compared with calculations using the simplified Monte Carlo method of Love et al. (1977). It is concluded that the Monte Carlo model predicts too high a peak to the X-ray distribution and that the discrepancy is worse at lower overvoltage ratios. Calculated surface ionisation functions Phi (0) are, however, closer to experimental values and the general shape of the Phi ( rho z) curve is considered satisfactory. The more rigorous model of Myklebust et al. (1976) also overestimates the height of the peak in the Phi ( rho z) curve and, whilst it performs rather better than the simplified model for gold, it gives even more unrealistic data on carbon.
TL;DR: In this article, it is argued that dividend policy is not determined as a residual, but rather that firms adopt independent dividend and investment policies, based on a questionnaire survey, which supports this view.
Abstract: In this paper it is argued that dividend policy is not determined as a residual, but rather that firms adopt independent dividend and investment policies. Empirical evidence, based on a questionnaire survey, supports this view. Independent dividend and investment policies are possible because debt finance is usually raised in sufficient quantities to accommodate the financial demands created by dividend and investment decisions.
TL;DR: In this article, the effect of hygrothermal conditioning on the fatigue behavior of carbon fiber/PEEK composite is compared with that of carbon/ epoxy material of similar construction.
Abstract: The fatigue behaviour of carbon fibre/PEEK composite is compared with that of carbon/ epoxy material of similar construction, particularly in respect of the effect of hygrothermal conditioning treatments. Laminates of both materials were of 0/90 lay-up, and they were tested in repeated tension at 0° and at 45° to the major fibre axis. The superior toughness of the polyether ether ketone and its better adhesion to the carbon fibres results in composites of substantially greater toughness than that of the carbon/epoxy material, and this is reflected in the fatigue behaviour of the carbon fibre/PEEK. The tougher PEEK matrix inhibits the development of local fibre damage and fatigue crack growth, permitting a 0/90 composite with compliant XAS fibres to perform as well in fatigue as an epoxy laminate with stiffer HTS fibres. Hygrothermal treatments have no effect on the fatigue response of either material in the 0/90 orientation. The fatigue response of a cross-plied carbon/PEEK laminate in the ±45° orientation is much better than that of equivalent carbon/epoxy composites, again because the superior properties of the thermoplastic matrix.