Showing papers by "University of Warwick published in 1977"

Forecasting Economic Time Series

Abstract: This book provides a formal analysis of the models, procedures, and measures of economic forecasting with a view to improving forecasting practice. David Hendry and Michael Clements base the analyses on assumptions pertinent to the economies to be forecast, viz. a non-constant, evolving economic system, and econometric models whose form and structure are unknown a priori. The authors find that conclusions which can be established formally for constant-parameter stationary processes and correctly-specified models often do not hold when unrealistic assumptions are relaxed. Despite the difficulty of proceeding formally when models are mis-specified in unknown ways for non-stationary processes that are subject to structural breaks, Hendry and Clements show that significant insights can be gleaned. For example, a formal taxonomy of forecasting errors can be developed, the role of causal information clarified, intercept corrections re-established as a method for achieving robustness against forms of structural change, and measures of forecast accuracy re-interpreted.

Phosphorylation of chloroplast membrane polypeptides

Abstract: ILLUMINATION of chloroplast thylakoids leads to the formation of the so-called high energy state of the membrane1–3. The establishment of this state is accompanied by several structural changes within the membrane, including a conformational change in the coupling factor4, increased accessibility of photosystem II to the chemical probe p-diazonium benzene sulphonate5, and a reduction in the thickness of the partition between stacked thylakoids6. I describe here a rather different type of structural change that has not previously been reported for chloroplast membranes—protein phosphorylation. Like the above changes, protein phosphorylation is a reversible, energy-dependent membrane modification, but it differs from the other changes in that it takes the form of a specific chemical reaction involving certain identifiable chloroplast membrane polypeptides. The most conspicuous of these polypeptides is the light-harvesting chlorophyll a/b binding protein, the most abundant thylakoid polypeptide7.

A Relativised Variational Principle for Continuous Transformations

Abstract: The formula (1.1) also follows from (1.2). Actually we prove a more general relative variational principle by considering pressure instead of entropy, and this result generalises the variational principle in [7]. This relative variational principle is stated in §2 (Theorem 2.1) after some definitions. §3 contains the proof of Theorem 2.1, and this proof is a generalisation of Misiurewicz's elegant proof of the (nonrelative) variational principle [5]. For simplicity of exposition we state and prove the results only for the action of one transformation T, but they can be readily extended to a continuous action of the semi-group Z +.

Lucid, a nonprocedural language with iteration

Abstract: Lucid is a formal system in which programs can be written and proofs of programs carried out. The proofs are particularly easy to follow and straightforward to produce because the statements in a Lucid program are simply axioms from which the proof proceeds by (almost) conventional logical reasoning, with the help of a few axioms and rules of inference for the special Lucid functions. As a programming language, Lucid is unconventional because, among other things, the order of statements is irrelevant and assignment statements are equations. Nevertheless, Lucid programs need not look much different than iterative programs in a conventional structured programming language using assignment and conditional statements and loops.

Social accounting matrices for development planning1

Abstract: The construction of three social accounting matrices (SAMs) for Iran, Sri Lanka, and Swaziland is described. The SAMs focus particularly on the distribution of income through disaggregation of household sector income and outlay accounts consistent with more conventional disaggregation of production factors. The SAMs were conceived as an initial step toward understanding income distribution as an integral part of the development process and have been developed parallel to work on planning models. The SAM approach has proved to be a practical working tool of considerable merit in making the best use of available data in providing a quantitative basis for analysis. The refined SAM approach, which uses separate commodity and activity accounts, is valuable for implementation of a SAM and as an aspect of subsequent modeling. It is desirable to disaggregate the household sector and build income distribution into the macroeconomic picture. The case studies demonstrate the empirical feasibility of going beyond existing national accounts toward an approach that is more interesting and useful for policy purposes. 32 references.

Distributed parameter system indentification A survey

Abstract: This report presents a survey of methods for the Distributed Parameter System Identification Problem. Fundamental concepts such as ‘ System Identification ’ and ‘ Distributed Parameter Systems ’ are briefly summarized in order to make precise what kind of problem will be considered here. The various identification methods are grouped into three disjoint classes, namely : ‘ Direct Method ’, ‘ Reduction to a Lumped Parameter System ’ and ‘ Reduction to an Algebraic Equation ’. Under this classification we give a general survey of the main approaches to the problem of identification in distributed systems

Cultivated and wild host plants supporting populations of the cabbage root fly

Abstract: SUMMARY To determine the relative importance of different potential host plants for supporting populations of the cabbage root fly, wild and cultivated crucifers were sampled for pupae at four locations during 1971-3. In addition, eighty-three species of Cruciferae native to or naturalized in the British Isles were inoculated with cabbage root fly eggs in a glasshouse to determine which species could support the larvae. In the field, most pupae (28-7/plant) were collected from untreated cauliflowers. Fewer pupae (i-7–8-6/plant) were obtained from untreated crops of Brussels sprout, cabbage and swede. Applications of chlorfenvinphos reduced populations to two or less pupae per plant on all crops. Of five common weed species sampled, only Raphanus raphanistrum produced as many pupae as certain of the untreated brassica crops. Pupae did not occur in samples from Capsella bursa-pastoris but Sisymbrium officinale, Thlaspi arvense and Sinapis arvensis usually supported low numbers. In the glasshouse, only forty-four of the eighty-three cruciferous species tested supported larval development. Most pupae were obtained from 12-wk-old plants of Barbarea intermedia. B. stricta, Brassica napus, Cochlearia officinalis and R. raphanistrum and from 24-wk-old plants of Brassica rapa, Erysimum aureum, Cochlearia anglica and C. officinalis. Plant age considerably affected pupal production. Plants within a genus often gave similar results, pupae not being recovered from any of the Diplotaxis or Arabis species tested, or from young plants of Erysimum spp. In other families, Reseda lutea and R. luteola supported larval development, but the widely-separated Plantago major did not. Arguments for and against the removal of cruciferous weeds from the vicinity of cruciferous crops are discussed.

The perception of musical rhythm and metre

Abstract: The occurrence of relatively long notes, and the repetition of melodic phrases are important cues to the metre, or regular beat, of a piece of music. A model of how people use this information to infer the metre of unaccompanied melodies is described here. The model is in the form of a computer program, and involves a definition of melodic repetition which encompasses repetitions that include certain kinds of variation. The program has been applied to the task of analysing the metric structure of the forty-eight fugue subjects of the Well-Tempered Clavier by J S Bach. The program is discussed in relation to other models both of musical understanding and of sequential concept learning.

Ammonia oxidation by the methane oxidising bacterium Methylococcus capsulatus strain bath

Abstract: Soluble extracts of Methylococcus capsulatus (Bath) that readily oxidise methane to methanol will also oxidise ammonia to nitrite via hydroxylamine. The ammonia oxidising activity requires O2, NADH and is readily inhibited by methane and specific inhibitors of methane mono-oxygenase activity. Hydroxylamine is oxidised to nitrite via an enzyme system that uses phenazine methosulphate (PMS) as an electron acceptor. The estimated Kmvalue for the ammonia hydroxylase activity was 87 mM but the kinetics of the oxidation were complex and may involve negative cooperativity.

The role of visual communication in synchronising conversation

Abstract: Previous research on visual interaction has indicated that Looking1 may serve a number of important functions in social interaction. In particular, the apparent relationship between the timing of Looks and the patterning of speech has led to the suggestion that visual communication serves to regulate the flow of conversation and to synchronise transitions from speaker to speaker. This was tested in the present experiment by comparing face-to-face dyadic encounters with similar discussions which took place over an audio intercom link which precluded visual communication. Simultaneous speech, which resulted generally from interruptions, occurred more frequently and for longer in total face-to-face than in the audio condition, while the length of utterances and the incidence of speech disturbance were both greater in the audio condition. This pattern of findings was quite different from that predicted, and suggests that the role of visual communication is to allow participants to converse spontaneously and interrupt freely by enabling them to send and receive nonverbal signals which maintain the interaction and prevent the breakdown which interruption might otherwise threaten. Suggestions for testing this interpretation further are outlined.

The formation of single-phase Si-Al-O-N ceramics

Abstract: Si-Al-O-N ceramics have been prepared by hot-pressing mixtures of Si3N4, AIN and SiO2 (with an addition of 1% MgO) having varying ratios of AIN/SiO2. Microstructural analysis by transmission electron microscopy and Auger electron spectroscopy has demonstrated the progressive increase in grain-boundary silicate glass in pressings prepared from compositions with excess SiO2 to compositions given by the formula Si6−zAlzOzN8−z. This formula represents the simple substitution of Al for Si atoms and O for N atoms in the hexagonalβSi3N4 crystal. Microstructures for this “balanced” composition are essentially single phase, consiting of non-faceted, sub-micron,β′ grains with a grain-boundary segregate layer of glass-forming silicate composition, containing impurity and additive metal ions, which may be detected only by Auger spectroscopy. This microstructure is in contrast with “unbalanced” compositions which contain facetedβ′ grains joined by a glassy silicate phase which is easily detected by electron microscopy. Final microstructural analysis combined with observations of density and phase content with progress of hot-pressing has confirmed the important role of liquid silicate formation and a “solution-reprecipitation” mechanism for densification. The presence of a 1% MgO additive is shown to accelerate this process, forming a low melting point silicate by reaction with SiO2, assisting the early solution of AIN and the reprecipitation ofβ′ substituted crystals.

Analytical formulae for d.c. hopping conductivity degenerate hopping in wide bands

Abstract: Analytical formulae for d.c. hopping conductivities are derived for degenerate hopping in wide energy bands. The formulae are in good agreement with computer data for two- and three-dimensional systems. For impurity conduction in n-type crystalline Ge they give hopping conductivities within a factor of four of those observed experimentally. The formulae are also used to analyse T 1/4 data in amorphous Ge and T 1/3 data obtained from studies of inversion layers in MOSFET devices. In both cases, reasonable values for the system parameters are deduced.

The peasant mode of production in the work of a. v. chayanov

Abstract: Is there a peasant mode of production? Chayanov's work can be construed as a theory of the peasant mode of production at the level of the labour process. This labour process is analysed in terms of the forces of production, the relationship between the peasant and the means of production, and that between the peasant and the product. When subjected to an historical critique, from the point of view of the formation and decomposition of the peasantry, Chayanov's theory of a peasant mode of production yields to the idea of peasantry as a specific combination of structures.

Leaves Without Holonomy

Abstract: This result is also due independently to G. Hector [3], who has shown how useful it can be in understanding the geometry of certain foliated manifolds. In such applications one sometimes needs a form of this theorem which applies to foliated subspaces, for example a minimal subset of a foliation. In fact our proof goes through unaltered in the situation where M is a locally compact, paracompact, Hausdorff foliated space such that each plaque is locally connected. We do not need to assume that M is a manifold. (We recall that locally compact Hausdorff spaces satisfy the Baire category theorem.) Our treatment of the result differs from that of Hector in several respects. Firstly we give complete details of the proof. Secondly we allow the manifold which is foliated to be non-compact. Thirdly we do not restrict the differentiability class of the foliation. Later we will give an example to show that T may be empty if M is not paracompact. We note that if M is a paracompact manifold, then the interior of T may e empty, and we will give an example which displays this behaviour.

Industrial Revolution in England and France: Some Thoughts on the Question, “Why was England First?”

Abstract: A MAJOR concern of economic historians since World War II has been to interpret the process of industrialization in now developed countries. One prominent line of approach has been to compare the experience of the European economies in the eighteenth century, and much of the inquiry has been conceptualized along the following lines. "The Industrial Revolution poses two problems: (i) Why did this first breakthrough to a modern industrial system take place in Western Europe? and (2) Why, within this European experience, did change occur when and where it did ?" 2 This comparative approach has been seen as a particularly valuable way of yielding insights into the process of economic growth in general and the causes of the English Industrial Revolution in particular. Thus Crouzet argues that "The economic historian interested in the key problem of growth is bound to find the comparative approach particularly fruitful. A systematic comparison of the eighteenth-century English economy with that of another country-and France as the leading continental power at that time seems the obvious choice-should bring out more clearly what factors were peculiar to England and might have determined what is a unique phenomenon, the English Industrial Revolution of the eighteenth century."3 Since Crouzet wrote, much of the literature has accepted the usefulness of the question, "Why was England first ?" and the specific question, "Why did England experience the onset of the Industrial Revolution before France ?" has been promoted to a position of great prominence.4 There is by now an extensive literature offering a wide variety of responses to these questions. The answers seem to fall into three types. First, there are studies which single out a single crucial reason. To cite just a couple of examples we find views as diverse as those of Kemp ("if one overriding reason can be given for the slower transformation of the continent ... it must be the continued prevalence of the traditional agrarian structures")5 and Hagen ("the differences in personality rather than differential circumstances are the central explanation of Britain's

Genome of infectious bronchitis virus.

Abstract: Techniques are described for the growth and rapid purification of the avian coronavirus infectious bronchitis virus (IBV). Purified IBV has a sedimentation coefficient of 320S and a buoyant density of 1.22 g/ml in sucrose-deuterium oxide equilibrium gradients. IBV RNA extracted by proteinase K in the presence of sodium dodecyl sulfate and further purified by phenol extraction and gradient centrifugation is single stranded and has a sedimentation coefficient of 64S, as determined by isokinetic gradient centrifugation. Analysis on sucrose gradients under both aqueous and denaturing conditions together with agarose gel electrophoresis in the presence of the chaotropic agent methylmercuric hydroxide gave a value of 8 X 10(6) for the moleclar weight of IBV RNA. This value was confirmed by RNase T1 fingerprinting, which also indicated that IBV RNA is haploid. No evidence was found of subunit structure in IBV RNA. From these results together with the recently reported observation that IBV RNA is infectious and contains a tract of polyadenylic acid (Lomniczi, J. Gen. Virol., in press), we conclude that the genome of the coronaviruses is a single continuous chain of about 23,000 mononucleotides that is of messenger polarity.

Persistence of the herbicide AC 92,553, N-(1-ethylpropyl)-2,6-dinitro-3,4-xylidine, in soils

Abstract: The effects of soil temperature and soil moisture content on the rate of loss of N-(1-ethylpropyl)-2,6-dinitro-3,4-xylidine (I, AC 92,553) were measured under controlled conditions. The time for 50% disappearance in a sandy loam soil at 75% of field capacity was inversely related to temperature (98 days at 30°; 409 days at 10°). At 25°, the half-life increased with decreasing soil moisture content (122 days at 75% of field capacity; 563 days at 12.5%). In seven soils with different properties there was a trend towards a slower rate of loss as the organic matter content of the soils increased and the half-life varied from 72 to 172 days, first-order kinetics being obeyed. The herbicide was lost rapidly from an inert surface and 97% loss was recorded after 28 days at 25°. Losses from soil surfaces occurred more slowly and were greater from wet compared with dry soil. In the field, it was more persistent when incorporated than when applied to the soil surface. More than 60% of I incorporated in April 1975 could be detected the following September, but when applied to the soil surface, only about 20% of the applied dose remained by this time. Residues measured by gasliquid chromatography using a thermionic nitrogen detector closely paralleled those measured by a bioassay based on the root growth of buckwheat.

A Sex Difference in the Platelet Count

Abstract: SUMMARY. A study of the platelet counts of 868 blood donors aged 18-65 showed a higher mean count in women than in men, the difference in the premenopausal age groups being highly significant (P

Neck rot (Botrytis allii) of bulb onions I. Seed-borne infection and its relationship to the disease in the onion crop.

Abstract: SUMMARY Experiments on neck rot of onions, caused by Botrytis allii showed that, although the disease only became evident in store, a major source of the pathogen was samples of infected seeds. In 1972 and 1973, 39·5 and 71·4% respectively of commercial onion seed samples tested at Wellesbourne were infected. The pathogen was internal in seed and persisted for 3 ½ yr in infected seeds kept in a seed store at 10°C and 50% r.h. Seedlings raised from diseased seeds became infected by mycelial invasion of the cotyledon leaf tips from seed-coats many of which remained attached to the cotyledons when seedlings emerged from the soil. The fungus attacked the living tissues of these leaves symptomlessly, producing conidiophores only after the leaf tissue senesced and became necrotic. Because the fungus was symptomless, the rate of spread of the pathogen in onion crops was assessed by incubating successive samples of plants from the field in humid conditions when infected tissues developed conidiophores of the fungus. This method showed that the disease was progressive in onion crops spreading more rapidly in wet humid conditions (e.g. 1972) than in dry ones (e.g. 1973). The principal means of spread were probably fungal spores; conidiophores bearing spores being produced abundantly on plants in the field under high humidity. The fungus invaded the leaves of plants successively, first infecting each leaf at the tip and then growing downwards in the tissues and eventually invading the neck of the onion bulb via the leaves which emerged directly from the top of the neck. By harvest, the fungus was situated deep within the neck tissues of infected maturing onion bulbs.