Showing papers by "University of East Anglia published in 1981"
TL;DR: In this article, theoretical foundations about elastic behavior of composite materials have been presented and an analysis of tensors and elastic behavior is discussed, and the overall elastic behaviour of a composite body is also explained in detail.
Abstract: Publisher Summary This chapter presents theoretical foundations about elastic behavior of composite materials. A composite material is a heterogeneous solid continuum that bonds together a number of discrete homogeneous continua, each of which has a well-defined sharp boundary. It is understood that the bonding at the interfaces (and the continuity of each region) remains intact in the present circumstances where the entire mixture is to be placed in an equilibrated state of infinitesimal elastic strain by external loads and constraints. Each separate homogeneous region has its characteristic tensor of elastic moduli (in the stress–strain relation), which when anisotropic reflects a particular alignment of the crystallographic axes relative to the fixed Cartesian ones. A single phase consists of all those regions that share the same tensor of elastic moduli and perhaps also the same alignment of a geometrical shape and of crystallographic axes. This chapter presents an analysis of tensors and elastic behavior. The elastic field of a composite body is discussed. The overall elastic behavior of a composite body is also explained in detail.
347 citations
TL;DR: The stability of a cantilever depends on the balance of forces, motive and resistive, associated with the most critical mechanism of failure as mentioned in this paper, i.e., shear, beam and tensile failure.
Abstract: The stability of a river bank depends on the balance of forces, motive and resistive, associated with the most critical mechanism of failure. Many mechanisms are possible and the likelihood of failure occurring by any particular one depends on the size, geometry and structure of the bank, the engineering properties of the bank material, the hydraulics of flow in the adjacent channel and climatic conditions.
Rivers flowing through alluvial deposits often have a composite structure of cohesionless sand and gravel overlain by cohesive silt/clay. Bank erosion occurs by fluvial entrainment of material from the lower, cohesionless bank at a much higher rate than material from the upper, cohesive bank. This leads to undermining that produces cantilevers of cohesive material. Upper bank retreat takes place predominantly by the failure of these cantilevers. Three mechanisms of failure have been identified: shear, beam and tensile failure.
The stability of a cantilever may be analysed using static equilibrium and beam theory, and dimensionless charts for cantilever stability constructed. Application of the charts requires only a few simple measurements of cantilever geometry and soil properties. In this analysis the effects of cracks and fissures in the soil must be taken into account. These cracks seriously weaken the soil and can invalidate a stability analysis by affecting the shape of the failure surface.
Following mechanical failure, blocks of soil must be removed from the basal area by fluvial entrainment if rapid undermining and cantilever generation are to continue. Hence, the rate of bank retreat is fluvially controlled, even though the mechanism of failure of the upper bank is not directly fluvial in nature.
This cycle of bank erosion: undermining, cantilever failure and fluvial scour of the toe, operates over several flood events and has important implications for river engineering, channel changes, and the movement of sediment through fluvial systems.
339 citations
TL;DR: In this article, what counts as research was discussed in the context of educational research and the British Journal of Educational Studies: Vol. 29, No. 2, pp. 103-114.
Abstract: (1981). What counts as research? British Journal of Educational Studies: Vol. 29, No. 2, pp. 103-114.
322 citations
TL;DR: It is possible to use the single mouse islet for simultaneous measurements of insulin release and electrical activity in single micro-dissected mouse islets of Langerhans and the maximum spike frequency occurs at a lower glucose concentration than does maximum insulin release.
Abstract: A method has been developed for the simultaneous measurement of insulin release and electrical activity in single micro-dissected mouse islets of Langerhans. The effects of D-glucose have been studied in individual islets. Each islet was exposed to 0, 5.6, 11.1, 16.7, 22.2, 27.8 and 33.3 mmol/l glucose in a stepwise fashion. The minimum glucose concentration required to elicit spike activity is lower than that required to stimulate insulin release above basal levels and the maximum spike frequency occurs at a lower glucose concentration than does maximum insulin release. Following a reduction in glucose from 27.8 (or 33.3) to 5.6 mmol/l, membrane potentials returned to resting values within 2 min whereas insulin returned to basal values after 20 min. Increasing glucose from 5.6 to 27.8 mmol/l induced spike activity within 10 s; the insulin response was detected within 40 s. Thus, it is possible to use the single mouse islet for simultaneous measurements of insulin release and electrical activity.
247 citations
18 Oct 1981
TL;DR: A simple model for concurrently executing process trees, which gives a basis for matching the production of new tasks to the available resources, and a generalised interpretation of a familiar topology suited to the support of large, perhaps irregular, virtual process trees on a much smaller physical network.
Abstract: A wide variety of computational models, including the lambda calculus, may be represented by a set of reduction rules which guide the (run-time) construction of a process tree. Even a single source of parallelism in an otherwise lazy evaluator may give rise to an exponential growth in the process tree, which must eventually overwhelm any finite architecture.We present a simple model for concurrently executing such process trees, which gives us a basis for matching the production of new tasks to the available resources. In addition, we present a generalised interpretation of a familiar topology suited to the support of large, perhaps irregular, virtual process trees on a much smaller physical network.
223 citations
TL;DR: In this paper, the authors explore the relationship between organizations in ambiguous situations, the technology of choice and the uses of internal accounting systems (systems of cost accumulation, performance evaluation and budgetary control).
Abstract: This paper explores the relationship between organizations in ambiguous situations, the technology of choice and the uses of internal accounting systems (systems of cost accumulation, performance evaluation and budgetary control). Accounting systems are examined in terms of the two elements of March's technology of foolishness (Civilokonomen , May 1971, pp. 7–12). Relaxation of traditional prohibitions in choice behaviour against imitation, coercion and rationalization suggest that accounting systems might be understood both in terms of their impact on sustaining and influencing an organization's culture and language and in terms of their ideological and legitimizing influence in maintaining systems of power and control in organizations. Allowing playfulness in the choice process suggests that accounting systems might be designed to facilitate creativity and innovation in organizations, insofar as these characteristics are appropriate in contributing to organizational effectiveness.
190 citations
TL;DR: Carbon, oxygen and sulphur isotope data for transects across two pyrite-bearmg carbonate concretions, and their host sediments, from the Upper Lias of N.E. England show symmetrical zonation as mentioned in this paper.
153 citations
TL;DR: In this paper, the authors focus on the environmental and biological characteristics of agriculture which shape the process of technical innovation and identify some major problems inherent in, and specific to, the organization and management of agricultural research resources.
151 citations
TL;DR: In this article, the authors discuss the properties and preparation methods of furoxan and benzofuroxans and compare them with trifurazan and furazan.
Abstract: Publisher Summary This chapter discusses the properties and preparation methods of furoxans and benzofuroxans. The history of its structure is briefly outlined. Many furoxan structures are determined by crystallographic methods, and as a result the dimensions of the heterocyclic ring are known in a wide variety of fused and substituted examples. Dynamic resonance effects (DNMR)—signal-broadening and coalescence phenomena at medium and fast exchange rates—are characteristic of furoxans fused to aromatic rings. The spectrum of benzotrifuroxan is analyzed and compared with that of the trifurazan. The methods of benzofuroxans preparation are: (1) dimerization of nitrile oxides, (2) dehydrogenataion of dioximes, (3) preparations from olefins and nitrogen oxides, (4) miscellaneous furoxan synthesis, and (5) benzofuroxans and other aromatic-ring-fused systems. The simple deoxygenation of furoxans to furazans is provided. Furoxans can be reduced in a variety of ways, depending upon the conditions used. It includes: (1) catalytic hydrogenation, (2) reduction with complex hydrides, (3) reduction with phosphorus compounds, (4) reduction with dissolving metals and metal ions, (5) electrochemical and other reducing methods. The chapter considers the principal substituent groups on the furoxan ring and the reactions they undergo.
149 citations
TL;DR: In this paper, the i.r. and Raman spectra of a series of chromium(III) complexes [M III 3 O(OOCR) 6 L 3 ]X· x H 2 O have been analyzed in detail.
129 citations
TL;DR: A review of experiment and theory concerned with the atomic mechanisms of the sputtering process is given in this article, with a review of experiments and theories concerned with sputtering processes in general.
TL;DR: In this paper, the authors examined the spatial and seasonal distribution of signal-to-noise ratio and found that the highest values occur in summer and annual mean surface temperatures averaged over the Northern Hemisphere or over mid-latitudes.
Abstract: Although it is widely believed that increasing atmospheric CO2 levels will cause noticeable global warming, the effects are not yet detectable, possibly because of the ‘noise’ of natural climatic variability. An examination of the spatial and seasonal distribution of signal-to-noise ratio shows that the highest values occur in summer and annual mean surface temperatures averaged over the Northern Hemisphere or over mid-latitudes. The spatial and seasonal characteristics of the early twentieth century warming were similar to those expected from increasing CO2 based on an equilibrium response model. This similarity may hinder the early detection of CO2 effects on climate.
TL;DR: In this article, the selective introduction of substituents into carbohydrates and the hydrolysis, acetolysis, and isomerization of polyacetals is discussed, and it is shown that the acid-catalyzed isomerisation of carbohydrate acetals occurs with favored cleavage of only one of the two acetal carbon-to-oxygen bonds.
Abstract: Publisher Summary This chapter discusses the selective introduction of substituents into carbohydrates and the hydrolysis, acetolysis, and isomerization of acetals. Of all the selective, deprotection procedures that are available to carbohydrate chemists, the partial hydrolysis of polyacetals is probably the most familiar. The acetolysis reagent trifluoroacetic- anhydride-acetic acid shows specificity similar to that of the acetic anhydride-acetic acid-sulfuric acid reagent; however, it offers the important advantage of obtaining acetatehydroxy derivatives under mild conditions because of the greater hydrolytic liability of the O-(trifluoroacetoxymethyl) group compared to the O-acetyl group. Solely on the basis of product structure, the acid-catalyzed isomerization of carbohydrate acetals occurs with favored cleavage of only one of the two acetal carbon-to-oxygen bonds. Enzymic hydrolysis can often provide the means for solving a problem involving the partial hydrolysis of esters. Relatively little work has been reported on the sequential removal of phosphate groups by chemical means from compounds containing several such groups.
TL;DR: Apterous Rhopalosiphum padi on the first leaf of cereal plants, developed faster and were more fecund at seedling to stem extension of barley, at tillering to earing of oats and at stem extension and Earing of wheat.
Abstract: SUMMARY
Apterous Rhopalosiphum padi on the first leaf of cereal plants, developed faster and were more fecund at seedling to stem extension of barley, at tillering to earing of oats and at stem extension and earing of wheat. Feeding site on a mature plant also affected the rate of development and fecundity of the aphids; the largest and most fecund developed on the stems of oat and wheat plants. The consequences of these variations in reproductive performance are discussed in relation to the population dynamics of R. padi and its possible pest status in Britain.
TL;DR: In this paper, the effect of the seedbank on the return to equilibrium of the plant population following an initial disturbance is analyzed. But the model is restricted to a population of a species of annual plants, of which a proportion of the seeds remain dormant for at least one year.
TL;DR: Evidence is presented which shows that NH 3 assimilation in Chlamydomonas occurs exclusively via the glutamate synthase cycle in illuminated and darkened cells and those in which the internal level of NH 3 is elevated, indicating that glutamate dehydrogenase probably plays a catabolic rather than anabolic role in the N nutrition of the alga.
TL;DR: Alatiform nymphs of Sitobion avenae were first recorded on wheat in 1977 and 1978 when there were 0.6 aphids per tiller and reached a maximum proportion of 0.9 of the population despite a seventeen‐fold difference in aphid density between years.
Abstract: . 1. Alatiform nymphs of Sitobion avenae were first recorded on wheat in 1977 and 1978 when there were 0.6 aphids per tiller and reached a maximum proportion of 0.9 of the population despite a seventeen-fold difference in aphid density between years.
2. At the same aphid density per tiller there was a higher proportion of alatiform nymphs on the tillers at an advanced than at an earlier stage of plant growth.
3. Both pre- and post-natal crowding, and late stages of plant growth, were important in inducing the development of alatae in the laboratory.
4. Changes in the quality of the host plant through its previously reported effect on reproductive and survival rates, and its effect on alate induction and emigration was important in shaping the population dynamics of S.avenae on cereals.
TL;DR: The low-temperature magnetic circular dichroism (MCD) spectra of the 8Fe ferredoxin from Clostridium pasteurianum with potassium ferricyanide, followed by purification on Sephadex G-25 and DE-23 cellulose columns, gives a protein with an intense EPR signal at g 2.01 as mentioned in this paper.
TL;DR: The results of the intensive mapping of karyotypic frequencies in this region are presented, and the ways in which the chromosomal cline might be maintained are discussed.
Abstract: Narrow clines, especially those which involve chromosomal differentiation, have excited a great deal of interest recently, primarily because they are suggestive of incipient speciation (see Endler, 1977; White, 1978). Hewitt (1975), following on the work of John and Hewitt (1970), and Hewitt and John (1972), described a narrow interface between two chromosome races of the alpine grasshopper, Podisma pedestris. Over most of its range, which extends over Siberia, the European Alps, the northern Appennines, and the Pyrenees, this insect has (as far as we can tell) an XO sex chromosome system. In the Alpes Maritimes, however, a Robertsonian fusion between an acrocentric autosome and the X chromosome has led to the fixation over a wide area of a neo-XY sex chromosome system. The two races meet in the high mountain ridge which runs from east to west along the FrenchItalian border, and on into France (Fig. 1). Six areas were found in which the two races approached each other closely. At four of these, mixed populations, which included heterozygous females, were found. A detailed study has been made of the easternmost end of the cline, near Col de Tende (Fig. 2). This paper presents the results of the intensive mapping of karyotypic frequencies in this region, and discusses the ways in which the chromosomal cline might be maintained.
TL;DR: It is found that anaerobic conditions derepress the synthesis of glucosidase, and thus achieve a high concentration of the enzyme.
Abstract: Publisher Summary This chapter elaborates the similarities and differences among yeasts regarding their capacity to use disaccharides and other glycosides This chapter considers the location of hydrolysis; substrate specificity of the glycosidases; substrate specificity of the carriers of the glycosides; affinity of the glycosidases and of the carriers for their substrates; regulation, by induction or repression, of these glycosidases and carriers; and the effects of changes in the environment The first step in the utilization of the most common glycosides by a yeast is either their passage intact across the plasmalemma into the cytosol, or their hydrolysis outside the plasmalemma and then entry of some or all of the hydrolytic products into the cell Of all the glycosidases that are important for hydrolyzing exogenously supplied glycosides, β-D-fructofuranosidase (invertase) and α-D-galactosidase (melibiase) activities are well known to occur outside the plasmalemmata of yeasts It is found that anaerobic conditions derepress the synthesis of glucosidase, and thus achieve a high concentration of the enzyme
TL;DR: In this article, a temperature dependent rate factor is constructed from the Mellor and Testa (1969a) uni-axial compression data at uniaxial stress 1.18 × 10 6 N m −2 over the temperature range 212.15 K-273.
TL;DR: Hybrids between pure populations had reduced viability, and the viability of insects from the middle of the zone was still lower, showing that most (∼87 per cent) of the inviability was due to the breakup of coadapated gene complexes.
Abstract: Samples were taken from five sites in a transect across the hybrid zone between two chromosomal races of the grasshopper Podisma pedestris. Crosses were set up between insects from the same population, and between populations spanning the zone, and the early viability of the offspring was measured. Hybrids between pure populations had reduced viability, and the viability of insects from the middle of the zone was still lower, showing that most (∼87 per cent) of the inviability was due to the breakup of coadapated gene complexes. Although the total selection acting was strong (log. fitness reduced by S∼2·5), it was spread over a region wider than the dispersal range (350 m vs. 20 m). Hence, the selection on each locus contributing towards the inviability is weak (∼3 per cent). Many (∼150) independent chromosome segments act cumulatively to produce inviability at this stage in the life history. The implications of these findings for models of divergence are discussed.
TL;DR: The spectra of the oxidized state are also different from those of oxidized high-potential iron protein from Chromatium and should provide a useful criterion for distinguishing between four- and three-iron clusters in their highest oxidation levels.
TL;DR: In this paper, the dipolar decoupling, cross-polarization and magic angle rotation techniques with a home-built spectrometer system are described, and applications of the methods have involved organic compounds, polymeric materials and inorganic systems.
Abstract: 13 C n.m.r. experiments are described that use the dipolar decoupling, cross-polarization and magic angle rotation techniques with a home-built spectrometer system. The subsidiary experimental methods of ( a ) spin-echo Fourier transform, ( b ) magnetization flip-back, ( c ) non-quaternary suppression and ( d ) single-pulse excitation are mentioned, and the equipment is briefly described. Applications of the methods are presented that have involved organic compounds, polymeric materials and inorganic systems. Discussion centres on special features of solid state spectra such as ( a ) multiplicity of crystallographic sites, ( b ) chemical shift and bandwidth differences from solution state spectra, and ( c ) effects of coupling to heteronuclei. Emphasis is placed on the value of the experiments for structural chemistry, as in cases of tautomerism, polymorphism and hindered intramolecular motion.
TL;DR: The magnetic circular dichroism (MCD) spectra of the dithionite-reduced and thionine-oxidized forms of the molybdenum-iron protein, Kp1, from the nitrogenase of Klebsiella pneumoniae have been recorded between 300-1000 nm at temperatures from 1.5 to 120 K and at magnetic fields up to 5.1 T as mentioned in this paper.
TL;DR: In this article, an electrochemical method for the measurement of the effective concentration of surfaceactive substances of natural and synthetic origin in natural waters is described based on the suppression by surfactants of the polarographic streaming maximum occurring on the reduction wave of Hg(II) in aqueous solution.
TL;DR: Fecundity, growth and development were determined at a range of feeding levels and temperatures and compared with the component models for the predator rate of increase.
Abstract: . 1. Fecundity, growth and development were determined at a range of feeding levels and temperatures and compared with the component models for the predator rate of increase.
2. Fecundity and growth rate show a linear dependence on rate of consumption, while development rate conforms to an alternative non-linear model. The non-linearity of development rate is due to a dependence of weight gain during an instar on rate of consumption.
3. The primary influence of temperature is on the rate of consumption, limiting fecundity and growth rate at temperatures below the optimum for the stage, while higher temperatures have a deleterious effect. Temperature has a more direct influence on development rates, allowing comparable growth despite the variation in rates of consumption.
TL;DR: A simple and rapid radiochemical assay for measuring glutamate synthase activity in permeable cells and cell free extracts of Chlamydomonas revealed a strict coordinate synthesis of the two enzymes.
TL;DR: In this paper, the problems of converting environmentalism into modern western living are described, as are various remedies, ranging from new approaches to analysis to various forms of activity and association with the surrounding community.
Abstract: Environmentalism is as much an attitude of mind and a certain code of behaviour as an ideology. Therefore the educational challenge is to make environmentalism real, not merely a classroom abstraction. The problems of converting environmentalism into modern western living are described, as are various remedies, ranging from new approaches to analysis to various forms of activity and association with the surrounding community.
TL;DR: The conditions leading to a point of inflexion, loop cusp for parametric cubic curves and parametric B-spline cubic curves are investigated and some useful conclusions are obtained.
Abstract: The conditions leading to a point of inflexion, loop cusp for parametric cubic curves and parametric B-spline cubic curves are investigated. Some useful conclusions are obtained.