Showing papers by "University of Bath published in 1982"

Choice, Welfare and Measurement

Abstract: In the course of his distinguished career, Amartya K. Sen has scrutinized the foundations of economic theory and analysis. He has brought into sharper focus such concepts as choice, preference, rationality, aggregation, evaluation, and measurement, and applied these concepts to the economic issues underlying universal social concerns, among them inequality, unemployment, poverty, human welfare, liberty, rights, justice. The twenty essays in this book encompass both these aspects of Sen's economic endeavors.Kenneth Arrow has written that "Sen's mastery in the fields of social choice, the foundations of welfare economics, and, more broadly, distributive ethics and the measurement problems associated with these fields is unquestioned. The selection of articles fully reflects his work in this area ... a number of the papers are already classics."The author has provided a substantial introduction to the book that interrelates his diverse concerns and analyzes the wide-ranging discussions that were generated by the original papers, while stressing the central concepts and underlying issues.His writings are distributed among five topical sections: Choice and Preference, Preference Aggregation, Welfare Comparisons and Social Choice, Non-utility Information, and Social Measurement. The contributions have been collected from many journals in the fields of economics and public affairs and from books that were published between 1966 and 1980.Amartya K. Sen is Drummond Professor of Political Economy at Oxford, and Fellow of All Souls College.

Weak and strong uniform consistency of kernel regression estimates

Abstract: We study the estimation of a regression function by the kernel method. Under mild conditions on the “window”, the “bandwidth” and the underlying distribution of the bivariate observations {(X i , Y i)}, we obtain the weak and strong uniform convergence rates on a bounded interval. These results parallel those of Silverman (1978) on density estimation and extend those of Schuster and Yakowitz (1979) and Collomb (1979) on regression estimation.

Methods for Analysing Spatial Processes of Several Types of Points

Abstract: Two approaches are described to the analysis of spatial patterns consisting of several types of points. The first approach uses a method of asymptotically unbiased estimation of the second moment distribution; the second uses methods based on regions of empty space in the patterns. Some distributional results are given in each case, and a method of Monte Carlo testing conditional on the marginal structure is described. The methods are illustrated by being applied to some physiological data.

Manufacturer-Overseas Distributor Relations and export Performance

Abstract: The export arrangement which makes use of overseas distributors is examined in this article. Although this method is important for many manufacturers operating in foreign markets there are reservations about the performance levels that are achieved under such arrangements. It is suggested that there is an important link between the performance level achieved and the very nature of the relationship that exists between the manufacturer and overseas distributor. The authors assert also that the nature of the manufacturer-overseas distributor relationship is associated with certain characteristics of the participating companies; namely, their stake in the relationship, their experience, and their uncertainty surrounding the relationship. These propositions are tested and largely corroborated through analysis of data collected from 41 companies in Canada and the UK.

Properties of avian egg shells and their adaptive value

Abstract: Summary I. An arbitrary classification of avian eggshells is proposed. 2. The role of the eggshell in conserving the water in eggs at oviposition is discussed. There is as yet no correlation between this property and the pore systems in avian eggshells. 3. The pore systems may act as diffusion pathways and the hypothesis has been advanced that in many eggs the shells are adapted so that restriction of gaseous diffusion by mud, preening oils and nest debris is prevented. 4. The mechanical properties of the shell are considered in the novel context of defence against (a) attrition that could lead to the pores being blocked with dust, and (b) cracking that would destroy the diffusion pathways noted in 3. 5. The overall objective of the review was to discuss the concept that avian eggshell are adapted to fit an egg to the nest environment.

Elasticity Theory of Composites

Abstract: The determination of the overall elastic moduli of random composites is approached using variational principles. Information on the configuration of a composite is never complete, and strict estimates can do no more than take the form of bounds that use whatever statistical information is available. The classical Hashin–Shtrikman bounds are deduced as special cases of bounds that allow explicitly for any two-point correlations, and it is shown that these general bounds take a simple form not given before for any two-phase composite. Self-consistent estimates are related to the variational formulation. Bounds of higher order are discussed and equations that define a new optimum bound of third order are given explicitly. The concluding Sections treat wave propagation problems from the standpoint of a new variational principle which reduces to the Hashin–Shtrikman principle in the static limit.

Risk and rationality

Abstract: Acceptable Risk. By Baruch Fischhoff et al. Pp.185. ISBN 0-521-24164-2. (Cambridge University Press: 1982.) £15, $19.95. Risk/Benefit Analysis. By Richard Wilson and Edmund Crouch. Pp.218. ISBN US 0-88410-667-5; ISBN UK 0-66-60514-8. (Ballinger/Harper & Row: 1982.) $23.75, £16.95.

Natural production of tritium in permeable rocks

Abstract: Natural tritium production by the reaction, 63Li(n, α)31H, may in some circumstances lead to 3H contents in the fracture fluids of a granite, which are significantly above the present natural 3H content (0.5 tritium units, TU) of pre-bomb precipitation. We show here that the principal factors which determine the 3H content of the fracture fluids are the U, Th, Li and B contents of the rock and its matrix porosity. Granites with high U, Th and Li contents; low B content and a low matrix porosity may have a naturally maintained 3H content of up to about 2.5 TU in water within the matrix. This has important implications for the interpretation of groundwater flow patterns from their 3H contents. Whereas it has generally been assumed that ground-waters with 3H contents greater than 0.5 TU have a proportion of post-1954 recharge present, this may not always be a valid conclusion.

On the indentation hardness of insect cuticle

Abstract: The indentation hardness of locust cuticle was measured using a Vickers diamond applied to the surface of the cuticle. A number of areas of cuticle showed similar hardness values, approximately 24 kg mm−2, for the dehydrated cuticle but the mandibles (29.8 kg mm−2) and the dorsal mesothorax (33.3 kg mm−2) were harder. The mandibles have localized areas of hardness which are related to their function. It is suggested that the hardness of the dorsal thorax may be related to its function as an energy storing structure in flight. The measured hardness of cuticle depends on the hydration of the material but relative differences between cuticles from different parts of the locust persist whether tested fresh or after dehydration. Hardness is correlated with the dihydroxyphenol content of cuticle (unlike stiffness), conversely it is not correlated with the hydrophobicity of the matrix proteins (unlike stiffness). It is emphasized that hardness and stiffness are very different mechanical properties.

Structure and bonding in crystalline boron and B12C3

Abstract: The first complete set of electronic structure calculations are reported for elemental boron in its alpha -rhombohedral (12 atoms per unit cell), beta -rhombohedral (105 atoms) and suggested alpha -tetragonal (50 atoms) crystalline forms. The results show that a band picture provides an accurate description of the bonding in these solids. The alpha -rhombohedral structure is found to produce semiconducting properties, with an indirect gap of 1.7 eV. The ordering of bands can be qualitatively interpreted in terms of the internal molecular orbitals of a B12 icosahedron and the two-centre and three-centre external bonds linking neighbouring icosahedra. Replacement of the electron-deficient bonds by linear C3 units gives the much stronger B12C3 structure, in which the calculated gap increases to a direct 3.8 eV. In the more complicated beta -rhombohedral elemental structure, a forbidden gap approximately 2.7 eV occurs in the spectrum of electron states. Some degree of defect- or impurity-induced disorder seems essential to stabilise the structure, since the valence band of the 'ideal' structure can accommodate 320 electrons per unit cell, compared with the 315 available. In the suggested alpha -tetragonal modification of pure boron, the electron deficit would be so severe that this structure probably occurs only for compounds such as B50C2 and B50N2.

Platelets from diabetic subjects show diminished sensitivity to prostacyclin.

Abstract: . Prostacyclin, an unstable metabolite of arachidonic acid metabolism, has been shown to have potent platelet antiaggregatory and vasodilator activity. Available evidence suggests that arterial prostacyclin production is diminished in the diabetic state. In this study we have examined the sensitivity of platelets from diabetic subjects to the antiaggregatory effects of prostacyclin in vitro and report that platelets from some diabetic patients show diminished sensitivity to the antiaggregatory effects of prostacyclin. Thus diabetic subjects may not only have diminished prostacyclin production but also their platelets may be less sensitive to its effects. These findings may help to explain the increase in vascular disease observed in diabetic patients.

Mapping of Reed-Muller coefficients and the minimisation of exclusive OR-switching functions

Abstract: A new geometric format, the bj coefficient map, is here introduced, the entries in which are the {0, l} coefficient values of the Reed-Muller Exclusive-OR expansions by which any given combinatorial function may be expressed. Although similar in format to the classic Karnaugh map, the bj map entries do not represent the function output in the same manner as do the minterm entries plotted on a Karnaugh map. It is shown that this coefficient map structure may readily be used to generate any required Exclusive-OR realisation of a given function, and provides a deeper insight into the coefficient relationships which arise when input variables are complemented in any Exclusive-OR expansion.

Reducing the effect of complexity on volume model evaluation

Abstract: A major problem with volume modelling systems is that processing times may increase with model complexity in a worse than linear fashion. The authors have addressed this problem, for picture generation, by repeatedly dividing the space occupied by a model, and evaluating the sub-models created only when they meet a criterion of simplicity. Hidden surface elimination has been integrated with evaluation, in such a way that major portions of the model which are not visible are never evaluated. An example demonstrates a better than linear relationship between model complexity and computation time, and also shows the effect of picture complexity on the performance of the process.

The carbohydrate composition of onions during long term cold storage.

Abstract: Onions cv Robusta were cold stored at 4°C and 70% RH at the end of three successive growing seasons from 1978-1980. The carbohydrate contents at harvest, after drying and during storage were measur...

Application of the Landau theory to elastic phase transitions

Abstract: The Landau theory of phase transitions has been applied to elastic phase transitions pertaining to crystals belonging to each of the 32 crystallographic point groups. Investigation of the Landau free-energy expansions provides information about: (i) the order of the possible transitions, (ii) the associated acoustic mode (which for a second-order transition should soften completely at the transition temperature) and (iii) the higher-order elastic constant contributions to thermal expansion only. Emphasis has been placed on finding the form of third-order invariants (the fourth-order terms also have been obtained for cubic crystals), which are needed in any quantitative assessment of the applicability of the Landau theory to elastic phase transitions in which the order parameter is just a strain tensor component. Application of the theory to the f.c.c. to f.c.t., transition in In-TI alloys is discussed.

Spatial structure of a population of tricholomopsis platyphylla in a woodland site

Abstract: SUMMARY Isolates of the mycelial cord-forming agaric, Tricholomopsis platyphylla, were obtained from an oak stand and their mating and mycelial interactions studied. The fungus was found to have tetrapolar incompatibility and genetically different dikaryons were strongly mutually antagonistic in culture. On the basis of such antagonism, 22 mycelial types, each comprising from one to 15 isolates were identified amongst a random sample of 113 dikaryotic mycelial isolates from an area of 20·8 ha. Isolates belonging to the same mycelial type were frequently found in close proximity in areas from which other types were excluded. However, some were from samples as much as 150 m apart and separated by areas occupied by other mycelial types. The likely origin of this distribution is discussed in relation to the pattern of dispersal, establishment and spread of this saprophytic fungus in a woodland habitat.

The thermal springs of Bath

Abstract: Geochemical and hydrogeological evidence shows that the thermal springs at Bath originate from the Mendip Hills. A maximum subsurface temperature of 80±16 °C is attained during circulation to between 2.7 and 4.3 km within the Carboniferous Limestone. The residence time of the bulk of the water is <10,000 yr.

A work role perspective of accountants in local government service departments

Abstract: In most of the largest U.K. local authorities the financial control function is highly centralised with no qualified accountant or controller located in each spending department. There now may be the beginnings of a trend towards employing accountants within service departments. The paper analyses how this new segment of public sector accounting appears to be becoming established, how the role of these accountants is being developed and the contrasting occupational values of accountants in service departments and those in the finance department. It is also shown how the existence of a strong accounting profession in local government can lead to different aspects of both the financial control structure and process in comparison with central government such that research results on the latter may not automatically hold at local level.

Population structure, inter-mycelial interactions and infection biology of Stereum gausapatum

Abstract: Isolates from wood, fruit body tissue and single basidiospores of Stereum gausapatum from several locations in South-West England showed several types of reaction when paired on 2% malt agar. ‘Compatible’ reactions resulted in the formation of a distinct secondary mycelium between monospore isolates. ‘Lytic’ reactions resulted in the development, between monospore isolates, of a crescent-shaped zone of appressed mycelium bounded by regions of liquid droplet exudation. In pairings between sibs, the distribution of these two reaction types showed a reciprocal relationship depending on which fruit body had been used for isolation. In non-sib pairings the compatible reaction predominated although, as in a few sib pairings, in many instances it appeared to follow an initial lytic reaction. A narrow pigmented zone of ‘mutual antagonism’ was usually formed between different wood or fruit body tissue isolates, or laboratory-produced secondary mycelia, and also between certain non-compatible/non-lytic combinations of monospore sibs. Some interactions between monospore sibs were ‘weak’, with little or no pigment production or other obvious effect. These observations suggest that S. gausapatum is heterothallic and that there is a link between the mechanisms underlying the lytic and compatible reactions. The implications in the infection biology of S. gausapatum and in relation to findings for other Stereum spp. are discussed.

Structure and development of mycelial cord systems of Phanerochaete laevis in soil

Abstract: The total length of a mycelial cord system of Phanerochaete laevis , present in the surface soil and litter of a deciduous woodland, increased from 1415 to 1479 cm over a period of 13 months. This increase was accompanied by loss of 270 cm from the central parts, and a corresponding proliferation at the periphery of the system. Mycelial growth from colonized beech blocks (approx. 8 cm 3 ) into 30 cm long glass tubes containing γ-irradiated soil showed little differentiation of cords and usually ceased well before reaching the ends of the tubes. By contrast, in similar tubes containing unsterilized soil, well-defined cord systems were formed which reached the ends of the tubes within about 15 weeks. These developed from an advancing front of more or less constant width containing numerous finely-branched cords. Following lysis at the rear of this front a relatively few large cords remained which were still connected to the blocks. Light inhibited mycelial development in the tubes in both γ-irradiated and unsterilized soil. After 15 weeks in the tubes wood blocks from γ-irradiated soil had undergone a greater loss in dry weight (22–27% compared with about 15%) and had a higher nitrogen content than those from non-irradiated soil.

Acoustic-Emission from Softwoods in Tension

Abstract: Acoustic emission (AE) monitoring is a non-destructive testing technique widely used to detect flaw development and crack propagation in metals, ceramics, polymers and composite materials. This paper relates the AE-strain characteristics from three softwoods tested in tension to mechanisms of deformation observed by scanning electron microscopy. All wood specimens are identical in size and radial-longitudinal in orientation, enabling the path of failure through planes of earlywood and latewood to be examined. It is found that the proportion of earlywood to latewood in each species has a marked effect on the shape of the AE-strain curves. Parana pine, containing very few latewood tracheids, exhibits a close to linear relationship between log cumulative emissions and strain until close to failure when the count rate increases rapidly. Douglas-fir, which has well-defined earlywood-latewood boundaries generates many AEs at low strain and there is greater variation in the shape of the AE characteristic between samples. Parana pine and Douglas-fir are tested at 20 °C (12.5 % EMC). Scots pine is also stressed at 20°C (12.5%EMC), 20°C (0.7%EMC) and 80°C (0.7%EMC), to assess the effect of moisture content on AE. Values of Young's modulus, stress at failure and work of fracture for the three softwoods are compared with the AE-strain data. Although the work of fracture is related to the total AEs to failure, no direct proportionality exists between the two parameters. Finally, the AE-strain data for plywood and glass-reinforced plastic (GRP), both man-made composite materials, are compared with those of wood, the natural composite material.

On optimal nonlinear feedback regulation of linear plants

Abstract: A design technique for optimal nonlinear regulation of linear plants, based on a homogeneous feedback law of degree 2p - 1 (p > \frac{1}{2}) , is developed.