Showing papers by "University of East Anglia published in 1980"
Abstract: Describes a new nuclear magnetic resonance (NMR) imaging technique which the authors call 'spin warp imaging' and gives examples of its application to human whole-body imaging. The apparatus is based on a four-coil, air cored magnet (made by the Oxford Instrument Company) capable of accepting the whole human body. The magnet produces a static field of 0.04 T giving a proton NMR frequency of 1.7 MHz. The maximum field inhomogeneity is about 6*10-4 at a radius of 0.23 m, approximately twice the amount theoretically attainable with this configuration. The pulse sequence used is shown.
817 citations
[...]
TL;DR: In this article, the authors defined climate as the prevailing influence or environmental conditions characterizing a group or period, defined by the Merriam Webster dictionary, and defined it as:
Abstract: Climate is, as defined by the Merriam Webster dictionary, the prevailing influence or environmental conditions characterizing a group or period. Climate is connected and intertwined in many ways with the four systems; the atmosphere, biosphere, lithosphere, and hydrosphere, and the four topics; meteorology, geology, oceanography, and astronomy of earth science. Each of these eight topics or systems help play a unique role in the trends of a specific region, known as the region’s climate.
460 citations
TL;DR: It is concluded that most plant populations will show neighbourhood stability with exponential or perhaps oscillatory damping towards an equilibrium, and the dynamical behaviour of plant populations is discussed.
289 citations
TL;DR: In this article, the dependence of elcctrophorctic mobility (uB) on pH and metal ion concentration (pM) indicates that carboxylic acid (-COOH) and phenolic (-011) groups are the major ionizable functional groups iti the organic fihn exposed to the solution.
Abstract: Measurements by the technique of particle electrophoresis rcvcal that different well charactcrizcd solid surfaces freshly cxposcd to seawater become covered by a tenacious film of natural surface-active organic matter which dominates their subsequent surface chemistry. The dependence of elcctrophorctic mobility (uB) on pH and metal ion concentration (pM) indicates that carboxylic acid (-COOH) and phenolic (-011) groups are the major ionizable functional groups iti the organic fihn exposed to the solution. Detailed treatment of the data on uK vs. pH and uE vs. pM allows calculation of intrinsic equilibrium constants for the dissociation of surface carboxylic acid groups and the complexation of metal ions by the organic film. The results obtained are in substantial agreement with data derived from more classical rlotentiometric titrations of marine and freshwater organic matter isolated by adsorption Or ultrafiltration methods.
178 citations
TL;DR: T1 measurements of human muscle, liver and brain tissue in vivo give results which agree well with T1 values for corresponding rabbit tissues measured in vitro.
Abstract: A nuclear magnetic resonance (NMR) machine capable of producing tomographic sections of the whole human body in vivo has been constructed. This system is based on a four coil, air-core electromagnet producing a field of 0.04 T which corresponds to a proton NMR frequency of 1.7 MHz. The images are produced line by line using a selective excitation technique. Magnetic field gradients up to about 5 mT/m are employed. Electronic subsystems are described here including a radiofrequency (RF) amplitude feedback circuit, an RF power amplifier, a transmit/receive switch, a receiver pre-amplifier and gradient coil drivers. For a single scan through a 103 mm3 sample of human muscle tissue in vivo, the measured proton density uncertainty is 24% and the spin-lattice relaxation time (T1) uncertainty is 74%. Phantom images using CuSO4 solution and in vivo sections through human chest, thighs and head are presented. T1 measurements of human muscle, liver and brain tissue in vivo give results which agree well with T1 values for corresponding rabbit tissues measured in vitro.
172 citations
TL;DR: Kinetic study of the formation and displacement steps has enabled the selection of substituents on the original pyrylium to optimise conditions for both steps for the selective conversion of primary amino groups into many other functionalities under mild conditions in high yields.
133 citations
TL;DR: In this article, the authors present plausible patterns for temperature and precipitation changes accompanying a general global warming, such as might occur due to a large increase in atmospheric carbon dioxide levels, by comparing the five warmest years in the period 1925-74 with the five coldest in this period.
Abstract: Plausible patterns for temperature and precipitation changes accompanying a general global warming, such as might occur due to a large increase in atmospheric carbon dioxide levels, are presented. The patterns are determined by comparing the five warmest years in the period 1925–74 with the five coldest in this period. Temperature increases are indicated for most regions, with maximum warming over northern Asia. A few isolated regions show cooling. Precipitation changes are fairly evenly distributed between increases and decreases; the most important features being an increase over India, and decreases in central and south-central USA and over much of Europe and Russia. The latter decreases, should they occur, could have considerable agricultural impact.
130 citations
TL;DR: In this paper, a review of the literature is assembled to show that in certain circumstances syndicate work produces striking results in the development of higher-order cognitive skills in higher education through small semi-independent student groups (syndicates).
Abstract: Summary This paper is concerned with the promotion of higher-order cognitive skills in higher education through small semi-independent student groups (‘syndicates˚s). In a review of the literature, evidence is assembled to show that in certain circumstances syndicate work produces striking results in the development of higher-order skills. Various contributory factors suggested by different authors to account for the effects in ‘successful˚s and ‘unsuccessful˚s classes are reported and a list is drawn up of the kinds of observations that need to be made to define the conditions.
126 citations
124 citations
TL;DR: In this paper, a steady plane flow under gravity of a symmetric ice sheet resting on a horizontal rigid bed, subject to surface accumulation and ablation, basal drainage, and basal sliding according to a shear-traction-velocity power law, is treated.
Abstract: Steady plane flow under gravity of a symmetric ice sheet resting on a horizontal rigid bed, subject to surface accumulation and ablation, basal drainage, and basal sliding according to a shear-traction-velocity power law, is treated. The surface accumulation is taken to depend on height, and the drainage and sliding coefficient also depend on the height of overlying ice. The ice is described as a general non-linearly viscous incompressible fluid, with illustrations presented for Glen’s power law, the polynomial law of Colbeck and Evans, and a Newtonian fluid. Uniform temperature is assumed so that effects of a realistic temperature distribution on the ice response are not taken into account. In dimensionless variables a small paramter ν occurs, but the ν = 0 solution corresponds to an unbounded sheet of uniform depth. To obtain a bounded sheet, a horizontal coordinate scaling by a small factor e(ν) is required, so that the aspect ratio e of a steady ice sheet is determined by the ice properties, accumulation magnitude, and the magnitude of the central thickness. A perturbation expansion in e gives simple leading-order terms for the stress and velocity components, and generates a first order non-linear differential equation for the free-surface slope, which is then integrated to determine the profile. The non-linear differential equation can be solved explicitly for a linear sliding law in the Newtonian case. For the general law it is shown that the leading-order approximation is valid both at the margin and in the central zone provided that the power and coefficient in the sliding law satisfy certain restrictions.
119 citations
TL;DR: In this paper, the authors show that the Newton-Raphson method can be used to solve the hypernetted chain equation for two-component ionic systems for a range of thermodynamic states spanning the aqueous solution and molten salt regimes.
Abstract: We show that the Newton-Raphson method recently developed for solving the liquid-structure integral equations can be used to solve the hypernetted chain equation for two-component ionic systems. The characteristics of the new method are studied by applying it to a model ionic system for a range of thermodynamic states spanning the aqueous solution and molten salt regimes. We find that its stability and rate of convergence are much superior to those of the usual method. There is a region of thermodynamic states in which the method fails to produce solutions. However, our results indicate that this is the region bounded by the spinodal line, within which the hypernetted chain equation possesses no physical solutions.
TL;DR: In this paper, first-appearance datums (FADs), twenty-three last appearance datums, and three other micropaleontological datums are related to the magnetic-reversal, oxygen-isotope, and calcite-dissolution/coarse-fraction time scales to provide a preliminary basis for subdivision of the Quaternary in deep-sea sediments.
TL;DR: Evidence is presented which shows that this photorespiratory N cycle in Chlamydomonas derives its N from protein rather than from freshly synthesised glutamate, suggesting that previous estimates of the amount of N recycled in photorespiration may have been too high.
Abstract: Work demonstrating the operation of a photorespiratory N cycle in Chlamydomonas is described. NH3 release by this process is light dependent, sensitive to changes in pO2 and pCO2, and abolished by a photosystem II inhibitor. Evidence is presented which shows that this NH3 derives its N from protein rather than from freshly synthesised glutamate. Protein turnover is shown to provide amino-N at a rate sufficient to account for the highest photorespiratory N excretion observed suggesting that changes in excretion can be accounted for by increased catabolism of normally recirculating amino acids. It is equally possible however that a direct link between photorespiration and protein turnover exists, increased NH3 excretion resulting from enhanced protein turnover. The data suggest that if similar mechanisms operate in higher plants, previous estimates of the amount of N recycled in photorespiration may have been too high.
TL;DR: In this paper, the British Educational Research Association (BEA) presented the annual conference of the British School Certificate Association (BSCA) in 1979, which was held at the University of Sheffield.
Abstract: *Presidential Address to the Annual Conference of the British Educational Research Association, September 1979.
TL;DR: The predatory net-spinning caddis larva Plectrocnemia conspersa aggregates in patches of high density during most of the year and the lack of an aggressive response in August may be due to aspects of environmental instability which make an optimal allocation of foraging effort between patches difficult to attain.
TL;DR: In this article, an experiment was carried out by separating a shallow man-made lake into two basins with an earth dam, and the results showed that in the basin to which fish had free access from the river, phytoplankton populations remained high, and no aquatic macrophyte community developed.
Abstract: An experiment was carried out by separation of a shallow man-made lake into two basins with an earth dam. Unintended leaks allowed extremely fertile river water to feed both basins so that nutrients were unlikely ever to have been limiting to phytoplankton populations. The two basins had greatly differing fish populations. In the basin in which these were low, a chain of events took place in which zooplankton grazing reduced phytoplankton growth sufficiently to allow establishment of aquatic macrophyte populations and an associated diverse benthic invertebrate community. In the basin to which fish had free access from the river, phytoplankton populations remained high, and no aquatic macrophyte community developed. The implications of these observations for shallow lake management are considered.
TL;DR: In this paper, the authors examined the contrast modes of transport and deposition of sandy and muddy contourites by hydrographic, photographic, lithologic, and seismic data from Hatton and Gardar sediment drifts in the Iceland Basin.
Abstract: The contrasted modes of transport and deposition of sandy and muddy contourites were examined by hydrographic, photographic, lithologic, and seismic data from Hatton and Gardar sediment drifts in the Iceland Basin, northeastern Atlantic Ocean. Gardar Drift is made of muddy contourites deposited from Iceland-Scotland Overflow Water with a thick and relatively intense nepheloid layer whose particles originate from Iceland. Hatton Drift is also mainly mud, possibly from Rockall Bank, but at its foot a strong northeast-flowing boundary current moves winnowed foraminiferal sand as ripples and low sand waves. The nepheloid layer on Hatton Drift is locally generated and is mainly in a stratum of North Atlantic Deep Water that is contaminated with Antarctic Bottom Water. This stratum, with it entrained particles, spreads across the basin as far as the crest of Gardar Drift. The bottom mixed layer over Gardar Drift is mainly thin (30-40 m) and indicative of depositional shear-stresses (u* 0.85 cm/sec over sands at the foot of Hatton Drift, the mixed layer is 90 m thick, but this thins to less than 40 m higher up on the drift as the environment changes from winnowing towards deposition.
TL;DR: In this article, a correlation of precipitation time series at stations with the time series of circulation indices and principal component analysis was identified by two different methods: correlation of the precipitation data at stations and the principal component analyses.
Abstract: New Zealand is a country with high relief that protrudes into the southern westerly circulation. Precipitation patterns are identified by two different methods: correlation of precipitation time series at stations with the time series of circulation indices and principal component analysis. Components were rotated to give more definite patterns. Examination of synoptic events and surface pressure anomalies in key months allowed the identification of the synoptic cause of each component pattern. The link between the components and circulation indices was investigated. The first method shows that precipitation is anomalously high on the windward side of the country to any airflow, and low on the leeward side. Component analysis revealed eight distinct patterns. All am related to synoptic events and surface pressure anomalies where humid air advects over a windward coast. Confirmation is provided by the patterns of correlations of precipitation associated with the circulation indices. These bear a c...
TL;DR: In this paper, the authors estimate the magnitudes of different processes affecting particulate matter in the microlayer: atmospheric deposition, Brownian diffusion, gravitational settling, bubble flotation and mixing.
TL;DR: In this paper, the physics of gas exchange at the air-sea interface are reviewed and the influence of gravity waves is discussed, and it is evident from scale considerations that the effect of gravity wave is small.
Abstract: The physics of gas exchange at the air-sea interface are reviewed. In order to describe the transfer of gases in the liquid near the boundary, a molecular plus eddy diffusivity concept is used, which has been found useful for smooth flow over solid surfaces. From consideration of the boundary conditions a similar dependence of eddy diffusivity on distance from the interface can be derived for the flow beneath a gas/liquid interface, at least in the absence of waves. The influence of waves is then discussed. It is evident from scale considerations that the effect of gravity waves is small. It is known from wind tunnel work that capillary waves enhance gas transfer considerably. The existing hypotheses are apparently not sufficient to explain the observations. Examination of field data is even more frustrating since the data do not show the expected increase of gas exchange with wind speed. DOI: 10.1111/j.2153-3490.1980.tb00974.x
TL;DR: In this paper, the infrared spectra of α-Fe 2 O 3 powders were measured in a study of surface structure and reactivity, and the experimental results give evidence that organic molecules put into contact with α-fe 2 o 3 activated in air or oxygen can generally be both physisorbed and chemisorbs on the surface.
TL;DR: The twisted cubic curve has the attraction of combining both commonly used curve definitions, the conic section and the parametric cubic, in a single form as mentioned in this paper, and a definition of the twisted cubic is developed in terms of geometric handles convenient for CAD and independent of parametrization, analogous to a well-known definition of conics.
Abstract: The twisted cubic curve has the attraction of combining both commonly used curve definitions, the conic section and the parametric cubic, in a single form. A definition of the twisted cubic is developed in terms of geometric ‘handles’ convenient for CAD and independent of parametrization, analogous to a well-known definition of conics. Conditions for the occurrence of asymptotes are investigated and shown to be considerably more complex than those for conics. Several more controllable subsets of the general curve are described. The paper concludes that use of the full generality of the twisted cubic is in most cases unjustified.
TL;DR: In vivo and in vitro photographic methods gave a consistent measure of nuclear involvement and it was found that it was not always possible to relate the changes in lens sodium to the extent of light scattering seen either in the in vivo or in vitro photographs.
TL;DR: In this article, the free-convective flow from a heated sphere, in the Boussinesq approximation, at high Grashof number, is considered, and the characteristics of the boundary layer close to the surface of the sphere are evaluated numerically.
Abstract: We consider the free-convective flow from a heated sphere, in the Boussinesq approximation, at high Grashof number. The characteristics of the boundary layer close to the surface of the sphere are evaluated numerically, and the eruption of the fluid from the boundary layer into the plume above the sphere is discussed.
TL;DR: In this article, a mathematical investigation into patterns of weaving reveals subtle problems in combinatorics and geometry, and a mathematical analysis of these patterns reveals the underlying structure of the problem.
Abstract: A mathematical investigation into patterns of weaving reveals subtle problems in combinatorics and geometry.
TL;DR: The high turnover rates for asparagine indicate that this compound is an important intermediate even under steady state conditions, and carries between 20 and 50% of the products of N assimilation.
TL;DR: In this article, a hydrogen adsorption site bridging two metal atoms is proposed for both the low coverage, β 2, and the high coverage β 1, states of hydrogen on W(100) and the change in the symmetric metal-hydrogen stretching frequency is correlated with the reconstruction of the tungsten surface in the β 2 state.
TL;DR: In this paper, the intensity distributions across several micrographs have been digitized at up to two million picture points and the data stored on magnetic tape, and the information from all points in a micrograph can then be plotted as a rosette diagram, or used in a regression analysis to determine the equation of the ellipse which most closely approximates the actual Rosette distribution.
Abstract: SUMMARY
Several methods exist for quantifying soil fabric information from electron micrographs, but hitherto little interest has been shown in digital computer techniques. This paper describes such a method for the quantitative analysis of the orientation of clay particles in electron micrographs. The intensity distributions across several micrographs have been digitized at up to two million picture points and the data stored on magnetic tape. By examining the gradient of the intensity variations in two orthogonal directions, the resulting intensity gradient vector at each point can be determined. The information from all points in a micrograph can then be plotted as a rosette diagram, or used in a regression analysis to determine the equation of the ellipse which most closely approximates the actual rosette distribution. Finally an index of anisotropy can be estimated from the major and minor axes of the ellipse.