Showing papers by "University of Reading published in 1986"

Mood and modality

Abstract: Since the publication of F. R. Palmer's first edition of Mood and Modality in 1986, when the topic of 'modality' was fairly unfamiliar, there has been considerable interest in the subject as well as in grammatical typology in general. Modality is concerned with mood (subjunctive etc.) and with modal markers such as English modal verbs (can, may, must etc.) and is treated as a single grammatical category found in most of the languages of the world. In his investigation of this category, Palmer draws on a wealth of examples from a wide variety of languages. He discusses in detail familiar features in a number of mainly European languages, and also looks at less familiar features including 'evidential' systems and the contrast of realis/irrealis, both to be found in unrelated languages.

Market Structure and Foreign Trade: Increasing Returns, Imperfect Competition, and the International Economy

Abstract: Market Structure and Foreign Trade presents a coherent theory of trade in the presence of market structures other than perfect competition. The theory it develops explains trade patterns, especially of industrial countries, and provides an integration between trade and the role of multinational enterprises. Relating current theoretical work to the main body of trade theory, Helpman and Krugman review and restate known results and also offer entirely new material on contestable markets, oligopolies, welfare, and multinational corporations, and new insights on external economies, intermediate inputs, and trade composition.

Analysis of the dynamics of African vegetation using the normalized difference vegetation index

Abstract: Images at a resolution of 8 km are currently being generated for the whole of Africa, displaying the normalized difference vegetation index (NDVI). These images have undergone a process of temporal compositing to reduce the effects of cloud cover and atmospheric variation. When the NDVI is plotted against time, different cover types are shown to have characteristic profiles corresponding closely with their phenology. The resultant pattern of NDVI values displayed on the images is analyzed in terms of the cover types present and local variations in rainfall. Comparison between images for 1983 and 1984 overall showed considerable similarities, but significant differences were observed in the northward extent of the greening wave in the Sahel, the greening up of the Kalahari Desert and East African communities. It is concluded that vegetation monitoring using NDVI images needs to be associated with scene stratification according to cover type.

Statistics in Language Studies

Abstract: This book demonstrates the contribution that statistics can and should make to linguistic studies. The range of work to which statistical analysis is applicable is vast: including, for example, language acquisition, language variation and many aspects of applied linguistics. The authors give a wide variety of linguistic examples to demonstrate the use of statistics in summarising data in the most appropriate way, and then making helpful inferences from the processed information. The range of techniques introduced by the book will help the reader both to evaluate and make use of literature which employs statistical analysis, and to apply statistics in their own research. Each chapter gives step-by-step explanations of particular techniques using examples from a number of fields, and is followed by extensive exercises. The early part of the book provides a thorough grounding in probability and statistical inference, and then progresses through methods such as chi-squared and analysis of variance, to multivariate methods such as cluster analysis, principal components analysis and factor analysis. None of these techniques requires the reader to have a grasp of mathematics more complex than simple algebra. Students and researchers in many fields of linguistics will find this book an invaluable introduction to the use of statistics, and a practical text for the development of skills in the application of statistics.

On the bias of maximum likelihood estimation following a sequential test

Abstract: SUMMARY Tlhe bias of maximum likelihood estimates calculated at the end of a sequential procedure is investigated For the two sequential designs considered in detail, the sequential probability ratio test and the triangular test, this bias is appreciable A method of calculating an adjusted estimate with reduced bias is described, and an approximation to the standard error of the new estimate is provided Examples of the implementation of the method are given, and its advantages and disadvantages relative to alternative approaches are discussed

Competitive adsorption of humus acids and phosphate on goethite, gibbsite and two tropical soils

Abstract: SUMMARY Competition in adsorption between humic acid (HA) or fulvic acid (FA) and phosphate on synthetic goethite, gibbsite and two tropical soils was studied. The results for both goethite and gibbsite showed that HA and FA competed strongly with phosphate for adsorption sites at low pH values. The soils showed a similar result with a reduction in phosphate adsorption resulting from the addition of HA at the pH of the soils. The competition between HA and phosphate at different pH levels is illustrated by comparing the adsorption envelopes for phosphate on goethite, gibbsite and the two soils in the presence and absence of HA. The trends observed may be explained by the relative positions of the maximum buffer-power (buffer capacity) of the organic acids and of phosphoric acid which are shown to lie in different pH ranges.

Concerning the effect of surface drag on the circulation of a baroclinic planetary atmosphere

Abstract: Extended runs of a multi-level spectral numerical model of atmospheric flow on a hemisphere have been used to investigate the effect of surface drag variations on the nature of the time-averaged flow. It is shown that the most drastic effect of reducing the surface drag is to permit strong horizontal, barotropic shears in the zonal mean flow, which inhibit baroclinic instability. This superficially paradoxical result is implicit in many earlier calculations, most clearly in the lifecycle description of nonlinear baroclinic instability, but appears not to be widely appreciated. The kinetic energy spectra are interpreted in terms of the wavenumber of the most baroclinically unstable normal modes KR, the Rhines blocking wavenumber Kβ, and a limiting wavenumber based on surface drag KD. The changes in KR and the smaller changes in Kβ as drag is reduced account satisfactorily for the changes found in the kinetic energy spectra.

Facilitation of learning and state dependency with nicotine.

Abstract: Two studies of nicotine and memory encoding were carried out using a state-dependent design. The first experiment used cigarettes and involved memory for stimuli that could not be encoded phonemically or semantically. The results of this recognition study show that nicotine was facilitating the input of non-phonemicably encodable and non-semanticably encodable information to storage and that nicotine produced state-dependent learning. The second study used nicotine tablets and involved memory for concrete words. The results of the free recall study show that nicotine produced state-dependent learning, that nicotine was facilitating the input of information to storage, but there was no evidence that associative processes had been changed by nicotine. These findings give no support for the suggestion that a cholinergic system in the brain is controlling the encoding of intrinsic cues relating to phonemic and semantic properties of things but not those involving mnemonic encoding by mental imagery, but rather that the cholinergic system is non-specifically involved in encoding.

Saponin content of soya and some commercial soya products by means of high‐performance liquid chromatography of the sapogenins

Abstract: Quantitative high-performance liquid chromatography of the sapogenins was used to estimate the saponin content of soya beans (Glycine max (L.) Merr.) and commercially prepared soya flours, protein concentrate, protein isolate and soya milks. The level of saponin in whole soya beans as estimated (0.47%) was in agreement with other recent estimates. Saponins were also found in the various soya flours (0.43–0.67%), protein isolate (0.76%), soya milks (0.022–0.026%) but not in the protein concentrate.

Mechanical design of hedgehog spines and porcupine quills

Abstract: (With 7 plates and 9 figures in the text) The spines or quills of hedgehogs and porcupines are morphologically and mechanically different. In simple terms, it seems that the quills of porcupines are proportioned to be as long as possible without bending too easily when loaded axially. By contrast, the spines of the hedgehog are as short as possible while still able to bend when loaded axially. In addition, the hedgehog spines have an internal morphology which delays the onset of local buckling under these loads, thus enabling the spines to absorb larger amounts of mechanical energy. By contrast, the quills of Hystrix are designed to break at the tip. Thus, whilst the quills of the porcupine seem to be well adapted for keeping an enemy as far away as possible, the spines of the hedgehog probably have this as an incidental function. Their main function is much more likely to be that of a shock absorber or storage of impact energy when the animal falls from a height, a behavioural attribute which is reportedly common.

Pollen wall formation in Lilium: The effect of chaotropic agents, and the organisation of the microtubular cytoskeleton during pattern development.

Abstract: Using a combination of electron-microscopic and immunocytochemical techniques the behaviour of the microtubular cytoskeleton has been followed throughout microsporogenesis in Lilium henryi Thunb. Cells treated with colchicine at specific stages and then permitted to develop to near maturity were used to investigate any participation by microtubules in the regulation of pollen wall patterning. The microtubular cytoskeleton assumes four principal forms during the meiotic process; in pre-meiosis it resembles that characteristic of meristematic somatic cells, during meiotic prophase it becomes associated with a nuclear envelope and, perhaps, with the chromosomes and, as the nuclear and cell divisions commence, it takes the form of a normal spindle apparatus. In the young microspores, microtubules assume a radial organisation extending from sites at the nuclear envelope to the inner face of the plasma membrane. No firm evidence was found linking any one of these forms of cytoskeleton with the generation of patterning on the cell surface. Experiments with colchicine revealed that the drug would readily dislocate the colpus, but did not affect the general reticulate patterning. The radial cytoskeleton was present during the deposition of the early primexine, but evidence from these and other studies (J.M. Sheldon and H.G. Dickinson 1983, J. Cell. Sci. 63, 191-208; H.G. Dickinson and J.M. Sheldon, 1984, Planta 161, 86-90) indicates patterning to be imprinted upon the plasma membrane prior to the appearance of this type of cytoskeleton. These results are discussed in terms of a recent model proposed to explain pattern generation on the surface of Lilium pollen grains, based on the "self-assembly" of patterning determinants within the plasma membrane.

The effect of shearing on the energy metabolism of the pregnant ewe

Abstract: 1. Metabolizable energy (ME) intakes, heat production, non-protein respiratory quotient (NPRQ) and the plasma concentrations of glucose, non-esterified fatty acids (NEFA), 3-hydroxybutyrate, insulin, growth hormone (GH) and cortisol were measured in shorn and unshorn pregnant ewes. 2. Lamb birth-weight was 17% higher from shorn ewes despite similar ME intakes in the two groups. Shearing resulted in a significant decrease in the digestibility of dry matter and energy. 3. Both shorn and unshorn ewes were found to be in positive nitrogen balance and negative energy balance. Heat production was 28% higher in shorn ewes. This increase in heat production in the shorn group could be completely accounted for by an increase in the oxidation of fatty acids as measured using the NPRQ values. 4. Despite an apparent increase in the use of fat as an energy source there were no effects of shearing on the mean plasma concentrations of NEFA, 3-hydroxybutyrate, GH and cortisol. 5. Measurements made at 1 h intervals for 24 h indicated a tendency for the concentrations of glucose to be increased and insulin decreased in shorn ewes, particularly, between 6 and 11 h after feeding. 6. It is concluded that shearing pregnant ewes at 8 weeks before lambing results in a chronic increase in energy requirements which are met by oxidizing body fat depots. The cold stress induced by shearing may also inhibit insulin secretion resulting in increased plasma glucose concentrations. The effects of shearing on energy metabolism in the ewe are discussed in relation to the nutrient supply for the developing fetus.

The duration of light and photoperiodic responses

Abstract: Exposure to alternating periods of light and darkness is a feature of the environment of most plants and animals. It is hardly surprising, therefore, to find that responses to the timing of these light/dark cycles are a nearly ubiquitous characteristic of life and that many of these responses represent useful adaptations to a fluctuating environment. A large number of biochemical events and several aspects of behaviour (such as ‘activity periods’ in certain animals and’ sleep movements’ in leaves) have been found to occur at a particular time of the day or night. For example, in the unicellular alga, Gonyaulax polyedra, there are two different manifestations of bioluminescence: low-intensity glowing which peaks towards the end of the night and high-intensity flashing which peaks in the middle of the night (Fig. 1c). In order to be able to locate an event at a particular time of day, the organism must possess some kind of timekeeping mechanism and must also be able to discriminate between light and darkness. Thus, daily timekeeping requires both a clock and a photoreceptor. When examined in detail it appears that in most, if not all cases the underlying clock is an endogenous oscillator which has certain characteristic properties in relation to light/dark cycles (Fig. 1). The photoreceptor, in contrast, varies widely between organisms.

Star multigraphs with three vertices of maximum degree

Abstract: The graphs we consider here are either simple graphs, that is they have no loops or multiple edges, or are multigraphs, that is they may have more than one edge joining a pair of vertices, but again have no loops. In particular we shall consider a special kind of multigraph, called a star-multigraph: this is a multigraph which contains a vertex v*, called the star-centre, which is incident with each non-simple edge. An edge-colouring of a multigraph G is a map o: E(G)→, where is a set of colours and E(G) is the set of edges of G, such that no two edges receiving the same colour have a vertex in common. The chromatic index, or edge-chromatic numberχ′(G) of G is the least value of || for which an edge-colouring of G exists. Generalizing a well-known theorem of Vizing [14], we showed in [6] that, for a star-multigraph G, where Δ(G) denotes the maximum degree (that is, the maximum number of edges incident with a vertex) of G. Star-multigraphs for which χ′(G) = Δ(G) are said to be Class 1, and otherwise they are Class 2.

Partiality, Favouritism and Morality

Abstract: Many philosophers are impartialists: they maintain that morality requires us to allocate our time and resources without according special preference to our own goals and interests and without displaying favouritism or partiality towards those to whom we happen to be in some way specially related. Despite its widespread support from various versions of utilitarianism, socialism, Christianity and other creeds, impartialism is untenable. First, the practical feasibility of impartialism is very much in doubt. All of us accord massive priority to our own plans and projects, careers, families, loved ones, friends; it is not easy to see how any normal human being could seriously attempt to set about dividing up his time and resources in a way which ignored self-referential categories such as 'mine' and 'ours'. Second, and more important, reflection reveals that it is very doubtful whether we should even try to adopt an impartialist ethic; for when applied to actual cases, impartialism, so far from being a shining ideal at which to aim, is exposed as morally suspect. To choose to save one's own child from a burning building when an impartial consideration of the balance of general utility would favour rescuing someone else first, is not (as impartialists must claim) a perhaps understandable but nonetheless regrettable lapse from the highest moral standards; on the contrary, it is the morally correct course it is precisely what a good parent ought to do. A parent who leaves his child to burn, on the grounds that the building contains someone else whose future contribution to the general welfare promises to be greater, is not a hero; he is (rightly) an object of moral contempt, a moral leper.' This much has been established in recent attacks on impartialism.2 But if impartialism is untenable, are there not equal problems with its contrary, partialism? That is the subject of this paper. I shall argue that the partialist faces serious difficulties but that these can be overcome. As a crude first shot, I define partialism as the thesis that it is (not merely psychologically

Heat stability of plasmin (milk proteinase) and plasminogen.

Abstract: The effect of heating on plasmin activity in various media, including phosphate buffer pH 7.0, skim milk, blood plasma, solutions of casein and solutions of whey proteins were investigated. Plots of log residual activity v. heating time were linear at all temperatures from 63 to 143 degrees C. In buffer solutions the presence of casein led to substantial substrate protection, the Arrhenius plots being linear both in the presence and absence of casein. The activation energy, Ea, for the inactivation reaction, was 62.4 kJ/mol in buffer alone and 58.4 kJ/mol with casein present at 25 mg/ml. In skim milk, despite the presence of casein at a similar concentration, plasmin was no more stable to heat than in buffer alone, and a curved Arrhenius plot was obtained indicating a more complex inactivation mechanism. Heating in the presence of proteins having free -SH groups accelerated the inactivation of plasmin. The role of -SH groups was confirmed by experiments with added alpha-lactalbumin, in which no free -SH groups occur, and reduced carboxymethylated beta-lactoglobulin, both of which were without effect. In blood plasma, plasmin was less stable to heat than in buffer (pH 7.0) or in skim milk. Plasminogen behaved very similarly to plasmin either when activated to plasmin with urokinase before heating or when activated afterwards. A hypothesis is presented to describe the heat inactivation and denaturation of plasmin. Technologically important findings are that in skim milk plasmin was largely unaffected by pasteurization conditions and 30-40% of its activity remained even after ultra high temperature processing conditions.

An improved method and medium for quantitative estimates of populations of Pythium species from soil

Abstract: A new medium, VP 3 medium (containing vancomycin, PCNB, penicillin and pimaricin), modified from Mircetich's MPVM medium, has been devised and tested. The VP 3 medium is much cheaper because of the small quantity of vancomycin used. It has been shown suitable for the collection and isolation of a wide range of diverse Pythium species and to give high counts for propagule densities from a range of cultivated and uncultivated soils. Surface-spread dilutions are recommended in preference to the incorporation of the dilution in cool molten agar. The degree of replication needed for retrieval of particular kinds of data has been assessed.