Showing papers by "University of Leeds published in 1981"
TL;DR: In this paper, the optimal timing of the switch from exporting to foreign-based production is investigated, and the authors present a simple model, which ignores set-up costs, and further extensions of the theory are considered in section 2.7 and 2.8.
Abstract: Analyses of the optimal timing of foreign direct investment (FDI) decisions have been curiously lacking in the general literature on multinational enterprises (cf. Buckley (1979a, b)). Although comparative static analyses exist, comparing exporting to the host country with market servicing from a production unit sited in the host country (Horst, 1971; Hirsh, 1976), the only attempt to predict the timing of the switch from exporting to foreign-based production is that of Aliber (1970) (although Vernon (1966) gives a cost-based rationale for the switch). This chapter attempts to fill this gap in the theory of FDI. Section 2.1 outlines and criticises previous attempts to deal with the problem, sections 2.2-4 present a simple model, which ignores set-up costs, and sections 2.5 and 2.6 give a more detailed analysis including such costs. Further extensions of the theory are considered in section 2.7, and the conclusions are summarised in section 2.8. The problem emerges as being more complex than had previously been appreciated.
509 citations
TL;DR: In this paper, the authors made an analysis of the rare earth contents of a suite of deep-sea (> 4000 m) seafloor nodules and associated sediments from the Pacific Ocean and found that 3 + REE concentrations are controlled by the surface chemistry of these phases during diagenetic reactions which vary with sediment accumulation rate.
456 citations
TL;DR: The apparent physiological flexibility of Microcystis seems well suited to growth and survival in the microenvironments encountered in eutrophic lakes.
Abstract: A 4 year series of field, light-microscope and ultrastructural observations is presented to illustrate biological aspects of the annual cycle of natural Microcystis populations enclosed in Lund tubes. Nine morphological stati, all referable to M. aeruginosa f. aeruginosa , feature at various stages of the cycle. Summer bloom-forming populations originate from vegetative colonial stock that overwinters on the bottom sediment each year, but there is no mass transfer of these colonies to the water column: intensive growth from individual cells in the old colonies leads to the formation of new infective colonies, being stimulated when the bottom water approaches anoxia and light penetrates to the bottom sediments. Growth is slow but the developing populations sustain only minor losses through grazing and settling out, eventually becoming dominant over other species. Allelopathy possibly contributes to this effect. In postmaximal populations, several mechanisms can contribute to net buoyancy loss and a (usually) rapid recruitment of vegetative colonies to the sediments is observed. Hypotheses are advanced to account for the observed behaviour, and some of these have been tested in the laboratory. The apparent physiological flexibility of Microcystis seems well suited to growth and survival in the microenvironments encountered in eutrophic lakes.
406 citations
TL;DR: In this article, the effect of scale on the shear behavior of joints is studied by performing direct shear tests on different sized replicas cast from various natural joint surfaces, and it is shown that scale effects are more pronounced in the case of rough, undulating joints, whereas they are virtually absent for planar joints.
396 citations
TL;DR: The difference in outcome between FS and US mothers is significant, and the most likely explanation is that supplementation has prevented some neural tube defects, but further studies are needed.
Abstract: An earlier preliminary paper is expanded. Women who had given birth to one or more infants with a neural tube defect were recruited into a trial of per conceptional vitamin supplementation. Two hundred mothers attending five centres were fully supplemented (FS), 50 were partially supplemented (PS), and 300 were unsupplemented (US). Neural tube defect recurrences in the study pregnancies were 1 (0.5%), in FS, none in PS, and 13 (4%) in US mothers. The difference in outcome between FS and US mothers is significant. The most likely explanation is that supplementation has prevented some neural tube defects, but further studies are needed.
329 citations
TL;DR: The work of Jean Piaget and others on the development of children's thinking has indicated that far from being the ‘tabula rasa of repute, pupils bring to their school learning in science ideas, expectations and beliefs concerning natural phenomena which they have developed to make sense of their own past experiences as discussed by the authors.
Abstract: Summaries English The work of Jean Piaget and others on the development of children's thinking, has indicated that far from being the ‘tabula rasa’ of repute, pupils bring to their school learning in science ideas, expectations and beliefs concerning natural phenomena which they have developed to make sense of their own past experiences. These alternate frameworks, in some cases strongly held and resistant to change, in others flexible and with many internal inconsistencies, have their influence on the effectiveness of formal school science programmes. Just as scientists in a period of ‘revolution’ in science have to make a paradigm shift, so pupils in moving from the ideas and beliefs they come to school with, to understanding and accepting the explanatory systems being offered, have to make a considerable journey in thought.
313 citations
282 citations
TL;DR: In this paper, a method was developed that enables the rare-earth elements (REE's) in terrestrial rocks to be measured simultaneously using the inductively coupled plasma (ICP) source spectrometer.
279 citations
TL;DR: Differences between primates; fissipedes, bovids and bipedal hoppers are demonstrated and departures from geometric similarity in mammals in general are noted and discussed.
Abstract: Measurements have been made of the leg muscles of mammals ranging from shrews Sorex to an elephant Loxodonta. Allometric equations based on body mass have been calculated for muscle masses, fibre lengths and moment arms and the thickness of a tendon, in several groups of mammals. Departures from geometric similarity in mammals in general (excluding bipedal hoppers) are noted and discussed. Differences between primates; fissipedes, bovids and bipedal hoppers are also demonstrated.
250 citations
233 citations
TL;DR: In this article, a review of current activity and importance in aero-acoustics is given, including the generation of sound and vorticity by sound and sound, respectively, the basis for, and consequences of, the application of a Kutta condition in unsteady leading and trailing-edge flows, and suppression or amplification of broadband hydrodynamic and acoustic fields in a jet under the influence of weak discrete tone forcing.
Abstract: This article gives a review of six areas of current activity and importance in aero-acoustics, including (i) the generation of sound and vorticity by vorticity and sound, respectively, (ii) the basis for, and consequences of, the application of a Kutta condition in unsteady leading- and trailing-edge flows, and (iii) the suppression or amplification of broadband hydrodynamic and acoustic fields in a jet under the influence of weak discrete tone forcing. The intention is also to promote acceptance once again of acoustics as a serious branch of fluid mechanics.
TL;DR: In this article, the distribution and actions of three spontaneously occurring wide-acting synaptic inputs on identified neurons of the visceral and right parietal ganglia of Lymnaea stagnalis are described.
TL;DR: Ferromanganese nodules from the Bauer Basin of the south equatorial Pacific are unlike virtually all oceanic nodules so far analyzed in showing negative Ce anomalies in their REE abundance patterns as discussed by the authors.
TL;DR: Bipedal hopping of kangaroo rats has been studied by making force plate records and X-ray cinematograph films simultaneously, and calculations show that energy saving by elastic storage is much less important than in kangaroos.
Abstract: Bipedal hopping of kangaroo rats has been studied by making force plate records and X-ray cinematograph films simultaneously. Calculations using the data so obtained, and
anatomical data, show that energy saving by elastic storage is much less important than
in kangaroos.
TL;DR: The amino acid sequence of the phosphorylase kinase delta subunit has been determined using cyanogen bromide peptides and the sequences of the N-terminal tripeptide and the amide assignments on residues 58 and 60 were not determined unequivocally.
Abstract: The amino acid sequence of the phosphorylase kinase δ subunit has been determined using cyanogen bromide peptides. These peptides were ordered by isolation of the tryptic peptides containing carboxy[14C]methylmethionine. The protein is identical to bovine uterus calmodulin and differs from bovine brain calmodulin only in amide assignments. The δ subunit contains 148 amino acids, including one residue of trimethyllysine, and has a molecular weight of 16680. The N terminus is blocked, probably with an acetyl group, and the protein has a net overall charge at pH 7 of –24. The asparagine residues 60 and 97 have been shown to be partially deamidated in the protein. The sequence of the N-terminal tripeptide and the amide assignments on residues 58 and 60 were not determined unequivocally.
TL;DR: The present work adds operations to the data types proposed by Scott and proposes an alternative to the equational specifications proposed by Guttag, Guttag and Horning and ADJ.
Abstract: A mathematical interpretation is given to the notion of a data type, which allows procedural data types and circularly defined data types. This interpretation seems to provide a good model for what most computer scientists would call data types, data structures, types, modes, clusters or classes. The spirit of this paper is that of McCarthy [43] and Hoare [18]. The mathematical treatment is the conjunction of the ideas of Scott on the solution of domain equations [34], [35], and [36] and the initiality property noticed by the ADJ group (ADJ [2] and [3]). The present work adds operations to the data types proposed by Scott and proposes an alternative to the equational specifications proposed by Guttag [14], Guttag and Horning [15] and ADJ [2]. The advantages of such a mathematical interpretation are the following: throwing light on some ill-understood constructs in high-level programming languages, easing the task of writing correct programs and making possible proofs of correctness for programs or implementations.
TL;DR: In this article, the authors surveyed available experimental data on the turbulent burning velocity of premixed gases and discussed the accuracy of experimental measurements and the means of ascertaining relevant turbulent parameters.
Abstract: Available experimental data on the turbulent burning velocity of premixed gases are surveyed. There is discussion of the accuracy of experimental measurements and the means of ascertaining relevant turbulent parameters. Results are presented in the form of the variation of the ratio of turbulent to laminar burning velocities with the ratio of r.m.s. turbulent velocity to laminar burning velocity, for different ranges of turbulent Reynolds number. A two-eddy theory of burning is developed and the theoretical predictions of this approach, as well as those of others, are compared with experimentally measured values.
TL;DR: In this paper, the authors used the distribution, microchemistry and internal structure of phases present in a slate as a basis for a discussion of the interaction between deformation and metamorphism in slates.
TL;DR: Overall, these data lend support to the view that a structurally specific ligand-estrogen receptor complex can influence the future events within a target tissue to produce either an agonist or an antagonist response.
Abstract: The estrogenic and antiestrogenic activities of tamoxifen ICI 47,699, enclomiphene, zuclomiphene, and the geometric isomers of monohydroxytamoxifen and CI628 were determined in the 3-day immature rat uterine weight test. Tamoxifen, enclomiphene, and the releated geometric isomers of monohydroxytamoxifen and CI628 were partially estrogenic with antiestrogenic properties. ICI 47,699 and zuclomiphene were predominantly estrogenic; however, an antiestrogen effect for zuclomiphene (100 micrograms daily) was demonstrable and large doses of ICI 47,699 (1 or 10 mg daily) inhibited full estrogen action. In contrast, the geometric isomers of monohydroxytamoxifen and CI628 related to ICI 47,699 and zuclomiphene were partially estrogenic with antiestrogenic properties. The estrogenic properties of ICI 47,699 were classified in three ways: elevation of uterine wet weight, increase in whole uterine DNA, and increase in the mitotic activity of luminal epithelial cells. In general, ICI 47,699 was able to initiate estrogenic responses of DNA synthesis or mitosis by translocation of fewer cytoplasmic estrogen receptors to the nuclear compartment than tamoxifen. A model is proposed to explain antiestrogen action in terms of the geometric requirements for receptor binding. It is suggested that the position in space of the alkylaminoethoxyside chain is of fundamental importance. Overall, these data lend support to the view that a structurally specific ligand-estrogen receptor complex can influence the future events within a target tissue to produce either an agonist or an antagonist response.
TL;DR: In this article, the creep and recovery behavior of ultra high modulus polyethylene has been studied over the temperature range 20 −70°C and four types of material were examined; low molecular weight and intermediate molecular weight homopolymer, an ethylene hexene-1 copolymer, and a sample prepared by γ-irradiation of isotropic low molecular-weight polymer prior to drawing.
TL;DR: In this article, the authors studied the Patagonian basalt plateau at latitude 45-47 °S from the Argentine-Chile frontier to Lago Colhue Huapi.
Abstract: From the Middle Jurassic onwards persistent igneous activity in the southern Andes around 46 °S was controlled by easterly dipping subduction along the Pacific margin. Cogenetic plutonic rocks belonging to the Patagonian batholith, and calc-alkaline volcanics ranging from basaltic andesites to rhyolitic tuffs and ignimbrites are the principal products. Erosion of the primary volcanics has led at various times to the development of thick volcaniclastic sequences, for example in the Cretaceous-Lower Tertiary Divisadero formation. The Coyhaique region marks the northerly extension of a narrow back-arc basin in which the marine Neocomian successions accumulated. Volcaniclastics from the island arc, which presumably lay to the west, are intercalated with the sediments. Although the marine basin was short-lived a mildly extensional back-arc regime may have existed through much of Mesozoic-Recent times. Widespread basalt-rhyolite volcanism on the eastern side of the cordillera seems to have been associated with this tectonic environment. Remnants of the Patagonian basalt plateau at latitude 45-47 °S extend from the Argentine-Chile frontier to Lago Colhue Huapi. Four principal age and compositional groups have been distinguished in the lavas, (i) The oldest, which are about 80 Ma, occur in sections at Senguerr and Morro Negro. They are almost exclusively tholeiitic, but show some calc-alkaline affinities and resemble in other respects basalts from marginal basins, (ii) The second group (57-43 Ma) occur in the lower part of the Chile Chico section with a compositional spread from olivine tholeiites through alkali basalts to one occurrence of a basanite. (iii) The upper part of the main plateau sequence, where the flows are in the range 25-9 Ma, are dominantly of alkali basalt composition, (iv) Post-plateau flows from small cinder cones on the surface of the plateau range in age from ca. 4 Ma to 0.2 Ma or less. They are mostly highly undersaturated basanites, with occasional leucite basanites, enriched in incompatible elements. A few of the earlier tholeiites with calc-alkali traits may have been closely associated with subduction or marginal basin processes. The younger lavas are more alkalic intraplate types generated in the remote back-arc extensional zone.
TL;DR: Body weight, potassium and nitrogen, muscle size, and leg performance and strength increased significantly during training on the drug, but not during the placebo period, suggesting that the weight gain was not only intracellular fluid.
Abstract: 1. In a previous study of the effects of methandienone (Dianabol) on men undergoing athletic training, strength and performance increased, but not significantly more when the subjects were taking the drug than when they were taking placebo. The subjects did, however, gain more weight on the drug, with increases in total body potassium and muscle dimensions. It remained an open question whether the muscles had gained normal tissue or intracellular fluid. 2. In an attempt to distinguish between these possibilities the trial has been repeated, using as subjects seven male weight-lifters in regular training, and including measurements of total body nitrogen. As before, a dose of 100 mg of methandienone/day was given alternately with the placebo in a double-blind crossover experiment. The treatment periods lasted 6 weeks and were separated by an interval of 6 weeks. Body weight, potassium and nitrogen, muscle size, and leg performance and strength increased significantly during training on the drug, but not during the placebo period. 3. The finding of increased body nitrogen suggested that the weight gain was not only intracellular fluid. The increases in body potassium (436 +/- SEM 41 mmol) and nitrogen (255 +/- 69 g) were too large in proportion to the weight gain (2.3 +/- 0.4 kg) for this to be attributed to gain of normal muscle or other lean tissue, and imply gain of nitrogen-rich, phosphate-poor substance. Although this action of methandienone might be described as anabolic, the weight gain produced is not normal muscle.
TL;DR: A further instance of induction formulated as a search is reported, and a review of the basic assumptions made by the Modelling System, LMS, and suggestions for some extensions are made.
TL;DR: In this paper, the authors investigated the Nd- and Sr-isotope characteristics of rocks involved in a relatively young (800-450 Myr) orogenic event, and used them to outline the range in age and geochemical characteristics of rock sequences and provinces within both the upper mantle and the pre-existing crust which were sampled during the orogeny, and hence provided the major components of what is now a stable segment of continental crust.
Abstract: The Nd-isotope analytical technique is a powerful tool for studying many geological processes: particularly the evolution of the upper mantle as seen through the isotope and trace element geochemistry of mantle-derived volcanic rocks1–3, and magmatic processes along destructive plate margins4,5. However, previous studies of continental crust6–8 have been largely restricted to Archaean examples and concerned primarily with dating their time of derivation from the upper mantle. In the present study we investigated the Nd- and Sr-isotope characteristics of rocks involved in a relatively young (800–450 Myr) orogenic event. Such events represent critical stages in the evolution of most of the Earth's continental crust—new material is added from the mantle, and pre-existing crust is remobilized by erosion and sedimentation, deformation and magmatic activity. Nd- and Sr-isotopes were used to outline the range in age and geochemical characteristics of rock sequences and provinces within both the upper mantle and the pre-existing crust which were sampled during the orogeny, and hence provided the major components of what is now a stable segment of continental crust.
TL;DR: A surface map of the paired pedal ganglia of Lymnaea stugnalis has been constructed and the accuracy of the map and interactions between ganglia are discussed.
TL;DR: In this paper, the ultrastructure of developing enamel from the rat incisor has been examined using a freeze-fracturing technique, showing that the forming region seems to consist largely of spheres 300-500 A in diameter.
TL;DR: The Archaean Karnataka craton of southern India contains Eastern and Western crustal blocks (separated by a major thurst) in which Sargur Schists occur as lenses within tonalitic Peninsular Gneisses as mentioned in this paper.
Abstract: The Archaean Karnataka craton of southern India contains Eastern and Western crustal blocks (separated by a major thurst) in which Sargur Schists occur as lenses within tonalitic Peninsular Gneisses. The Schist complex comprises pelites, quartzitic psammites, carbonates and calc-silicates, iron formations, and basic rocks, and thus provides many mineral assemblages ideal for the calculation of PT conditions. With their gneisses the Sargur rocks are unconformably overlain by the Dharwar greenstone belts, and are generally thought to be older than 3,000 my.
01 Nov 1981