Showing papers by "University of East Anglia published in 1977"
TL;DR: In this paper, a modified Shields-type threshold diagram is presented for sediment movement under unidirectional flow conditions, which extends the limits of the original diagram by three orders of magnitude in the grain-Reynolds number.
Abstract: Carefully selected data for the threshold of sediment movement under unidirectional flow conditions have been utilized to re-examine the various empirical curves that are commonly employed to predict this threshold. After a review of the existing data, we employed only that data obtained from open channel flumes with parallel sidewalls where flows were uniform and steady over flattened beds of unigranular, rounded sediments. Without these restrictions, an unmanageable amount of scatter is introduced. This selected data is used to develop a modified Shields-type threshold diagram that extends the limits of the original diagram by three orders of magnitude in the grain-Reynolds number. The equally general but more easily employed Yalin diagram for sediment threshold is also examined. Although the Shields and Yalin diagrams are general in that they apply to a wide range of different liquids, in both cases somewhat different curves are obtained for threshold under air than for the liquids. The often used empirical curves of the friction velocity u,, the velocity 100 cm above the bed ul,,,,, the bottom stress T, and Shields’ relative stress Bt, all versus the grain diameter D, are limited in their ranges of application to certain combinations of grain density, fluid density, fluid viscosity and gravity. These conditions must be selected before the curves are generated from either the more general Shields or Yalin curves. For example, on the basis of the data selected for use in this paper, empirical threshold relationships for quartz density material in water are uloo = 122.6 Do.2B for D 0.2 crn where the velocity uloo measured 100 cm above the sediment bed is given in cmjsec and the grain diameter D is in cm. The limitations on any of the threshold relationships are severe. These limitations should be properly understood so that the empirical curves and relationships are not improperly employed.
982 citations
TL;DR: In this paper, the concept, definition and measurement of a service is discussed, and various ways in which services can be classified for purposes of economic analysis are elaborated, and the distinction between private and public goods is re-examined in the light of the general concept of service proposed in the paper.
Abstract: The paper is concerned with the concept, definition and measurement of a service. Although services are often dismissed as immaterial goods, they are not special kinds of goods and belong in a quite different logical category from goods. The search for appropriate units of quantity in which to measure services is not an idle metaphysical pursuit. Without quantity units there can be no prices, and most economic theory becomes irrelevant. Indeed, large parts of economic theory may be irrelevant to the analysis of services anyway, precisely because they are not goods which can be exchanged among economic units. Services are as important as goods in modern developed economies and they need to be identified and quantified properly if the measurement of economic growth and inflation is to have any meaning for the economy as a whole. The concept of a service is explained in some detail in the paper, and various ways in which services can be classified for purposes of economic analysis are elaborated. The distinction between private and public goods, or rather between private and collective services, is re-examined in the light of the general concept of a service proposed in the paper. Externalities are shown to be simply special kinds of services.
789 citations
TL;DR: The hydrogeology of the karstic Carboniferous Limestone is described in this paper, where water tracing has established recharge areas for fifteen major springs and water budgets confirm the size of the areas found.
431 citations
TL;DR: In this paper, it was shown that a free surface wave is intrinsically a subsonic phenomenon and that the set of directions on a particular anisotropic elastic half-space in which such waves can travel is determined by the slowness surface of the material.
Abstract: Publisher Summary This chapter discusses that rapid progress has been made in recent years in the investigation of the basic aspects of the theory of surface waves in anisotropic elastic media. Solutions have been found to the fundamental problems concerning the existence and uniqueness of free surface waves, and in this respect, it can be claimed that a complete theory is now in existence. The outstanding new ideas have of late come from a rather unexpected quarter—namely, the theory of dislocations and results of major significance may consequently lie hidden from specialists in the dynamics of elastic materials who do not habitually attend to developments in this field. The chapter highlights that the possibility of oversight is not reduced by the dependence of the main contributions on a multitude of sources mostly located in the literature of solid-state physics, much of the precursory material having no obvious connection with elastic surface waves. Two broad insights into the character of elastic surface waves confirmed by the present study are that a free surface wave is intrinsically a subsonic phenomenon and that the set of directions on a particular anisotropic elastic half-space in which such waves can travel is determined by the slowness surface of the material.
396 citations
TL;DR: In this paper, measurements of longstream and cross stream velocities carried out across sections of a river perpendicular to the outer banks of several bends using an electromagnetic flow meter are reported.
Abstract: FLUIDS flowing through pipes or channels can develop secondary currents. These are defined as currents which occur in the plane normal to the local axis of the primary flow. Their development in straight channels has been ascribed to anisotropic turbulence and the non-uniform distribution of boundary shear stress1–3 but in meander bends they are generally caused by skewing of the flow3–5. Secondary currents distort the distributions of primary isovels and boundary shear stress from those expected in simple flows and, therefore, have important implications for bed and bank erosion and for resistence to flow. We report here measurements of longstream and cross stream velocities carried out across sections of a river perpendicular to the outer banks of several bends using an electromagnetic flow meter.
181 citations
TL;DR: In this paper, a source of CO2 in the unsaturated zone is proposed to account for this discrepancy, supported by direct measurements of CO 2 in fractures in cave walls and analyses of drip waters.
159 citations
TL;DR: In this article, the authors used computer simulations of ophiolites to derive a model for the formation of the upper oceanic crust and found that most of the dykes in their sheeted dyke units were intruded at spreading axes in zones less than 50 m wide.
Abstract: Summary
It appears that certain features of ophiolites can only have been formed by conveyor belt type sea-floor spreading. Computer simulations of these features are used to derive a model for the formation of the upper oceanic crust. Detailed structural studies of complete ophiolites reveal a remarkably consistent structure of their upper portions: lavas with occasional dykes grade down through a rapid transition into a sheeted dyke layer, which in turn grades down into gabbro through a second equally sharp transition. Where sufficient sections can be measured sheeted dyke units show consistent one way chilling, there usually being about 10 per cent more margins chilled one way than the other. Two entirely independent computer simulations (of one way chilling, and of the increase in dyke percentage with depth in ophiolites) show that most of the dykes in their sheeted dyke units were intruded at spreading axes in zones less than 50 m wide. The dykes are intruded vertically, and subsequently both dykes and lavas may be rotated by tectonic activity and buried by more lavas as they migrate out of the roughly 4-km wide zones of lava formation. This model of formation of oceanic crust based on ophiolite data is consistent with observations on the present mid-ocean ridges. It appears that similar processes involving a narrow zone of dyke intrusion are developed at all spreading plate boundaries where the spreading rate is greater than about 10 mm/yr, irrespective of possible variations in spreading rate or tectonic setting of the spreading axis. From the model a number of features of the oceanic crust can be explained: (1) the shape of the boundaries between the blocks that produce magnetic anomalies, (2) upwelling of hydrothermal circulation will be most intense in the axial 1 km at spreading axes, (3) sulphide deposits are most likely to be formed in this axial 1 km and will then be buried by subsequent lava flows and (4) metamorphism of the upper oceanic crust will be greatest in this axial zone so that metamorphic layering is produced as an integral part of the formation of the oceanic crust and not as a result of subsequent burial.
158 citations
134 citations
TL;DR: It is concluded that water in these systems is highly mobile, that water molecules affected directly by a macromolecule tumble anisotropically about all axes relative to the macromolescule with correlation times in the region of 10 -9 s at 260 K and that these molecules exchange with water molecules free of the influence of the macROMolecule with a lifetime in the dynamically oriented state of the order of 10-6 s at temperatures around 300 K.
Abstract: The basic principles of nuclear spin relaxation, dielectric relaxation and quasielastic neutron scattering and their use in studying the motions of water molecules are outlined. A summary is given of the time scales associated with the translational and rotational motions of water molecules and of intermolecular proton exchange in pure liquid water. A model is then proposed for the dynamics of water molecules in heterogeneous systems involving regions having differing compositions, water molecules within each region existing in environments both affected by interaction with the macromolecular components and free of their influence and including exchange of water molecules between different environments and regions. The lifetime of the interaction of water molecules with the macromolecular components is assumed long compared with the time for rotation of such bound molecules. Exchange of protons between water molecules and between water molecules and macromolecules is also considered. The ways in which such processes would be expected to affect the observed nuclear magnetic resonance, dielectric and neutron scattering behaviour are outlined. Particular emphasis is placed on nuclear spin relaxation phenomena and the existence and observation of residual dipolar and quadrupolar splittings in the n.m.r. spectra of 1 H and 2 H (D) nuclei in water molecules in such systems, these splittings arising from water molecules dynamically oriented at water/macromolecule interfaces. Details are then given of particular studies of water molecule dynamics in heterogeneous systems using n.m.r., dielectric and neutron scattering techniques. The systems discussed include moist protein powders, protein solutions, phospholipid/ water and soap/water mesophases, clay/water systems and biological polymers and tissues. It is concluded that water in these systems is highly mobile, that water molecules affected directly by a macromolecule tumble anisotropically about all axes relative to the macromolecule with correlation times in the region of 10 -9 s at 260 K and that these molecules exchange with water molecules free of the influence of the macromolecule with a lifetime in the dynamically oriented state of the order of 10 -6 s at temperatures around 300 K. The ability of nuclear magnetic relaxation studies to distinguish water in different regions of a tissue is discussed and examples are given of the study of the rate of water transport across membranes using these techniques.
114 citations
TL;DR: The rate constants for oxygen quenching in benzene solution of the triplet states of several organic compounds with relatively high triplet energies have been measured in laser photolysis and pulse radiolysis experiments as discussed by the authors.
110 citations
TL;DR: The average concentration of dissolved aluminium found in surface waters of the North Sea with salinities greater than 34‰, was 1·5 μg l−1, with a range of from 5·5 to 0·5μl−1. Approximately 30% of the dissolved aluminium entering the Conway Estuary in fresh water appears to be removed during mixing with seawater in the estuary as mentioned in this paper.
TL;DR: In this article, the authors measured the oxygen isotopic composition of cellulose, whole wood and lignin from tree rings in a white spruce (Picea glauca) which grew in the Edmonton area from 1882 to 1969.
Abstract: MEASUREMENTS of stable isotope ratios on tree rings have proved a promising way of determinating past climate1–5. Recent discussions have centred on which component of wood provides the most reliable record6,7. We have measured the oxygen isotopic composition of cellulose, whole wood and lignin from tree rings in a white spruce (Picea glauca) which grew in the Edmonton area from 1882 to 1969. Using meteorological records we have evaluated the responses of the 18O/16O ratios of the three components of the tree rings to seasonal temperatures. Results show a high correlation between cellulose 18O/16O ratios and mean annual temperature, a poorer, though still significant correlation between whole wood 18O/16O ratios and mean annual temperature and no significant correlation between lignin 18O/16O ratios and mean annual temperature.
TL;DR: Documentary evidence for the changes in the air pollutant levels and climate of London are compared with the results obtained from a simple single box model for the annual mean SO2 and particulate levels in the London air.
TL;DR: In this paper, the authors trace the change in the diatom communities of a 60 cm mud core through the stratigraphy of a 50 cm core and show that an epiphyte-dominated diatom community was replaced by a planktonic community.
Abstract: SUMMARY. Barton Broad, Norfolk is a shallow, eutrophic lake. During the last 30 years submerged macrophytes have declined and phytoplankton numbers have increased. This change is traced through the stratigraphy of a 60-cm mud core. Diatom frustule counts of 1-cm sections of the core showed that an epiphyte-dominated diatom community was replaced by a planktonic community. From chemical analysis and radio-isotope dating of the core, sedimentation rates and past phosphorus and iron loadings are estimated. Sedimentation rates were between 1.2 mm and 3.1 mm year−1 during the early part of the core but doubled in the 1950s to 5 mm year−1, doubled again in the 1960s and have increased to 12 mm year−1 in the 1970s. Retention of phosphorus in the sediment increased from 0.5 g m−2 year−1 to 18–21 g m−2 year−1 in two steps. A similar trend is shown for iron. The diatom species composition and chemistry of the core sections are correlated with increased nutrient loading and the decline of macrophytes. Contemporary phosphorus and iron budgets are calculated from inflow–outflow data and balanced using sediment retentions estimated from the core data. It is believed a large proportion of phosphorus and iron enters the Broad by movement of sediment along the river bed. A reduction of 25% of the 1975 phosphorus loadings would probably permit re-establishment of some macrophytes. The present chemistry and algal communities of Barton Broad and the River Ant are described.
TL;DR: In this article, a model for the dynamics of water molecules in heterogeneous systems involving dynamically oriented water molecules at interfaces exchanging with others remote from interfaces is developed further with respect to the spinrelaxation properties of the hydrogen isotopes in the water molecules.
Abstract: A model for the dynamics of water molecules in heterogeneous systems proposed earlier and involving dynamically oriented water molecules at interfaces exchanging with others remote from interfaces is developed further with respect to the spin-relaxation properties of the hydrogen isotopes in the water molecules A single-crystal system is considered in which all interfaces make the same angle with respect to an external axis Expressions are derived for the contributions of both exchange of water molecules between surface and bulk sites and intermolecular proton exchange to proton relaxation at low frequencies for a system in which the observed proton spectrum is a single line A density matrix treatment is used to describe the dependence on pulse separation of the deuterium transverse relaxation rate in such a system, measured using a 90° x′ (τ-90° y′-τ) n spin-echo sequence which removes the residual static quadrupole interaction, the source of the doublet deuteron spectrum It is shown that a study of
TL;DR: An analysis of pulmonary arterial impedance suggests that a large central arterial reservoir actively fills during systole and passively empties through a functionally single peripheral resistance during diastole.
Abstract: 1.
Blood pressures measured in lightly anaesthetized turtles (Pseudemys scripta) and tortoises (Testudo graeca) indicate that pressures throughout the ventricle are superimposable, but vascular impedances to blood flow in the pulmonary outflow tract and especially in the large extrinsic pulmonary arteries result in slightly lower pulmonary than systemic arterial systolic pressures in both species.
2.
Pulmonary outflow tract impedance is increased by vagal stimulation and acetylcholine and decreased by adrenaline. However, the pulmonary outflow tract apparently contributes little to the overall pulmonary impedance changes which occur during intermittent breathing.
3.
An analysis of pulmonary arterial impedance suggests that a large central arterial reservoir actively fills during systole and passively empties through a functionally single peripheral resistance during diastole. Morphological examination as well as in vitro compliance measurements and perfusion with drugs of the extrinsic pulmonary arteries corroborate these data by revealing a highly distensible central arterial reservoir nearly devoid of smooth muscle and vasomotor responses. The more distal pulmonary arteries are much less compliant, contain much smooth muscle, and show marked vasoconstriction in response to acetylcholine and vagal stimulation.
4.
Data on pulmonary impedance, morphology and pharmacology are incorporated into a classic ‘Windkessel’ haemodynamic model of the chelonian pulmonary circulation.
TL;DR: In this article, the authors quantify the way in which organic matter is transported from the atmosphere to the oceans, and they show that any modifying effect of material at the sea surface will vary depending on the mode of transfer, as well as the properties of the interfacial material.
TL;DR: It is suggested that glucose, by reducing the permeability of the plasma membrane to effluent K+, increases the concentration of K+ in the islet cells and under steady-state conditions, reduces proportionally the fractional turnover rate of the cellular K+ pool.
01 Jul 1977
TL;DR: In this article, the problem of forecasting the development of the well-known sunspot cycle of approximately 11 years from observations made early in the cycle is considered, where each cycle is described by a member of a family of curves with different parameters for each cycle.
Abstract: SUMMARY The problem of forecasting the development of the well-known sunspot cycle of approximately 11 years from observations made early in the cycle is considered. Each cycle is described by a member of a family of curves with different parameters for each cycle. Forecasts are obtained using this model and these forecasts are combined with forecasts obtained from an autoregressive model. Forecasting the time of maximum sunspot activity and the maximum sunspot number is also discussed.
TL;DR: The shape of the source blocks of oceanic magnetic anomalies can be determined from this structure as mentioned in this paper, particularly when the width of source blocks is large, which may explain several enigmatic features of magnetic anomalies and provide better matches of computed with observed anomalies than thin, vertical sided blocks.
TL;DR: The authors showed that epipsammic algae, though tolerant of darkness for many days, do not survive anaerobiosis for long and must rely on rapid movement to regain the sediment surface.
Abstract: Epipelic algae live freely on sediment surfaces, epipsammic algae live attached to grains in sandy sediments. Both groups may be buried by wave action and animal disturbance when they may find themselves in dark, deoxygenated layers. Epipelic algae, though tolerant of darkness for many days do not survive anaerobiosis for long and must rely on rapid movement to regain the sediment surface. Since they often are non-motile epipsammic algae cannot always move rapidly upwards. They tolerate both darkness and anaerobiosis, retaining considerable photosynthetic potential for several days in the complete absence of oxygen.
TL;DR: In this article, it was concluded that increase in turbidity is a function of increased nutrient loading from human activities in the catchment area and that boat disturbance does not contribute significantly to the sustained turbidity.
TL;DR: In this article, a specially designed test was used in three related investigations concerned with the ability of Nigerian secondary-school students to understand depth relationships in pictures, and a factor analysis showed that there were factors associated with the understanding of vertical, horizontal, and diagonal displacements, respectively.
Abstract: A specially-designed test was used in three related investigations concerned with the ability of Nigerian secondary-school students to understand depth relationships in pictures. The first investigation demonstrated that the percentage of students unable to achieve the criterion performance decreased significantly from 61.7% for second-year students to 22.5% for fifth-year students. Both groups were significantly poorer in performance than a sample of English third-year students. In the second investigation the understanding of these spatial relationships in diagrams was found to require a prior understanding of the same relationships in the corresponding three-dimensional object. In the third investigation a factor analysis showed that there were factors associated with the understanding of vertical, horizontal, and diagonal displacements, respectively.
TL;DR: In this paper, the solvent reorganisation energies associated with charge transfer spectroscopic transitions in molecules of ellipsoidal shape were calculated by a novel adaptation of the Kirkwood-Westheimer equations.
TL;DR: In this article, two experiments were carried out to compare the effectiveness of different ways of producing the frames in a remedial self-instructional program intended to improve the ability of Nigerian secondary students to understand spatial relationships in pictures.
Abstract: Two experiments were carried out to compare the effectiveness of different ways of producing the frames in a remedial self-instructional program intended to improve the ability of Nigerian secondary students to understand spatial relationships in pictures. In one experiment with Yoruba students, it was demonstrated that the use of stereoscopic pictures brought about an improvement in performance, whereas planoscopic pictures and models did not. In contrast, a second experiment with Hausa students showed that three programs involving stereoscopic diagrams, planoscopic diagrams, and planoscopic diagrams in conjunction with models, all brought about both short- and long-term improvements. There were no significant short- or long-term differences between the effects of the programs. Neither was there a significant decline in the learning from any program over a period of five months.
TL;DR: In this paper, a principal component analysis of a 101 year set of winter mean sea level pressure anomalies for the North Atlantic-European sector has revealed evidence of an 11-year cycle, which is apparently related to the long-term modulation of solar flare activity during the sunspot cycle.
Abstract: A principal component analysis of a 101 year set of winter mean sea level pressure anomalies for the North Atlantic-European sector has revealed evidence of an 11 yr cycle. This cycle is apparently related to the long-term modulation of solar flare activity during the sunspot cycle.
TL;DR: Three drug resistant strains are known, cyh1, anil and tri5 (resistant to cycloheximide, anisomycin and trichodermin respectively), in which resistace is conferred by an altered ribosome, in each case by an alters 60S sub-unit.
Abstract: The 80S ribosome of Schizosaccharomyces pombe contains 93 proteins as determined by twodimensional electrophoresis on polyacrylamide gels. Of these, 76 are basic and 17 are acidic at pH 8.7. 38 proteins could be assigned unambiguosly to the large sub-unit and 19 to the small. 67 proteins were extracted from the two-dimensional gels and their molecular weights determined by electrophoresis on calibrated SDS-gels. Values varied from 11,000 to 52,000 daltons, the number average being 25,000 daltons. Hence the total protein content of the 80S ribosome must be at least 1.67x106 daltons. Three drug resistant strains are known, cyh1, anil and tri5 (resistant to cycloheximide, anisomycin and trichodermin respectively), in which resistace is conferred by an altered ribosome, in each case by an altered 60S sub-unit. When 80S ribosomal protein patterns from these strains were compared with that of wild type, in only one case was a clear difference seen. This involved a large sub-unit, basic protein (designated number 66 on our classification) which, in the cyh1 strain, had a reduced mobility in the second dimension when compared to the wild type. The mutant form of protein 66 had a molecular weight of 25,000 daltons compared to the 22,000 of the wild type protein. Production of a larger protein by the mutant strain could either be due to a readthrough event or to an alteration in the specificity of a modifying or processing enzyme.
TL;DR: In this paper, the authors distinguish between three different kinds of drought (meteorological, hydrological and agricultural) and derive a time series of soil moisture deficits which they believe gives a more rational measure of agricultural drought severity.
Abstract: THE recent drought and water shortage in England has re-emphasized the need for a more detailed knowledge and better understanding of the climate of the past. Without such information it is impossible to make meaningful statistical statements about the future occurrence of such extreme events. Many meteorological statements have been made about the severity and causes of the 1976 drought, mainly in the popular press, but also in the scientific literature1. These statements have generally concerned precipitation; but data on precipitation alone are not necessarily good indicators of drought. In this paper we distinguish between three different kinds of drought—meteorological, hydrological and agricultural drought—noting that agricultural and hydrological drought conditions are determined, not only by rainfall, but also by evaporation and by the timing of rainfall events. Using both precipitation and evaporation data for Kew we derive a time series of soil moisture deficits which we believe gives a more rational measure of agricultural drought severity than can be obtained from precipitation data alone.