Showing papers by "University of Warwick published in 1981"
TL;DR: A general method for proving/deciding equivalences between omega-regular languages, whose recognizers are modified forms of Buchi or Muller-McNaughton automata, derived from Milner's notion of “simulation” is obtained.
2,256 citations
TL;DR: The concept image consists of all the cognitive structure in the individual's mind that is associated with a given concept and may have aspects which are quite different from the formal concept definition as discussed by the authors.
Abstract: The concept image consists of all the cognitive structure in the individual's mind that is associated with a given concept. This may not be globally coherent and may have aspects which are quite different from the formal concept definition. The development of limits and continuity, as taught in secondary school and university, are considered. Various investigations are reported which demonstrate individual concept images differing from the formal theory and containing factors which cause cognitive conflict.
1,751 citations
TL;DR: In photosynthetic membranes isolated from pea leaves, the redox state of the plastoquinone pool controls both the level of phosphorylation of the chloroplast light-harvesting pigment–protein complex (LHC) and distribution of absorbed excitation energy between the two photosystems.
Abstract: In photosynthetic membranes isolated from pea leaves, the redox state of the plastoquinone pool controls both the level of phosphorylation of the chloroplast light-harvesting pigment–protein complex (LHC) and distribution of absorbed excitation energy between the two photosystems. Phosphorylation of LHC polypeptides is proposed as the regulatory mechanism by which photosynthetic systems adapt to changing wavelengths of light.
660 citations
TL;DR: A review and a theoretical analysis of factors determining airway deadspace (VDaw) and alveolar dead Space (VDalv) and the two constituents of physiological dead space (VDphys) are presented, finding most causes of VDphys are influenced by inspiratory flow pattern and the time available for gas diffusion and distribution.
Abstract: We present a review and a theoretical analysis of factors determining airway deadspace (VDaw) and alveolar deadspace (VDalv), the two constituents of physiological deadspace (VDphys). VDaw if the volume of gas between the lips and the alveolar/fresh gas interface, the location of which is determined by inspiratory flow pattern and airway geometry. VDalv can be caused by incomplete alveolar gas mixing and associated V/Q mismatching within the terminal respiratory units, temporal V/Q mismatching within units, spatial V/Q mismatching between units, and venous admixture. Most causes of VDphys are influenced by inspiratory flow pattern and the time available for gas diffusion and distribution. Analysis can be made from the single breath test for carbon dioxide (SBT--CO2) which is the plot of fraction of carbon dioxide in expired gas against expired volume. The common causes of VDalv are associated with a sloping SBT-CO2 phase III. Combination of SBT-CO2 with PaCO2 yields VDphys and VDalv. A sloping phase III with a negative arterial-end-tidal PCO2 gradient implies compensation by perfusion for early emptying, overventilated alveoli.
313 citations
TL;DR: It is concluded that the newly synthesized light-harvesting chlorophyll a/b protein fail to accumulate in intermittently illuminated leaves because they undergo rapid turnover.
Abstract: 1
Antibodies raised against the 26000-Mr polypeptides of the light-harvesting chlorophyll a/b proteins of pea leaves specifically immunoprecipitated two 32000 -Mr polypeptides synthesized when pea leaf poly(A)-containing RNA was translated in vitro. On the basis of immunochemical relatedness and by comparison of their partial tryptic digestion products, the 32000 -Mr products formed in vitro are identified as precursors to the authentic polypeptides of the light-harvesting chlorophyll a/b complex.
2
The specificity of the immunoprecipitation permitted the development of an assay for the cellular levels of translationally active light-harvesting protein mRNA in plants exposed to different light regimes. Low levels of the mRNAs were detectable in dark-grown plants. Exposure to continuous illumination caused these levels to increase by at least ten-fold and led to the appearance of large quantities of the light-harvesting chlorophyll a/b complex. In plants exposed to intermittent illumination (2 min of white light every 2 h for 2 days), the light-harvesting complex did not accumulate, although levels of mRNA specifying the polypeptides of the complex were high (50% of those in continuously illuminated plants).
3
Messenger RNAs encoding the light-harvesting proteins were detected in polysomes of intermittently illuminated leaves. These polysomes were active in a wheat-germ 100000 ×g supernatant ‘run-off’ system, to form light-harvesting protein precursors, under conditions when only nascent polypeptide chains initiated in vivo were elongated and terminated. These results demonstrate that the inability of intermittently illuminated leaves to accumulate the light-harvesting proteins is not due to a selective inhibition of the translation of the corresponding mRNAs.
4
Intermittently illuminated leaves were labelled with [35S]methionine in darkness, and incorporation of radioisotope into the light-harvesting proteins and their precursors was assayed immunologically. No pool of untransported or unprocessed 32000 -Mr precursor polypeptides could be detected in the soluble fraction (cytoplasm and stroma). However, low levels of the mature 26000 -Mr polypeptides were detected in the membrane fraction. It is concluded that the newly synthesized light-harvesting chlorophyll a/b proteins fail to accumulate in intermittently illuminated leaves because they undergo rapid turnover. The site of light-harvesting protein breakdown is probably the thylakoid membrane, and the cause of breakdown is probably the absence of chlorophyll a and chlorophyll b molecules that are required for eventual stabilization of the proteins within the photosynthetic membrane.
269 citations
TL;DR: The law may be seen as a set of general principles through which political authority and the state (however constituted) attempt to legitimize the social institutions and norms of conduct which they find valuable.
Abstract: Perhaps the most intransigent problem in the recent history of Indian society remains an adequate understanding of the processes of social change which took place under colonialism. As the continunig controversies within, as much as between, the traditions of modernization theory, Marxism, and the underdevelopment theory make plain, the Indian historical record is peculiarly difficult to grasp with conventional sociological concepts. In the study of Western European society, a focus on the evolution of legal ideas and institutions has proved a useful entry point to social history.The law may be seen to represent a set of general principles through which political authority and the state (however constituted) attempt to legitimize the social institutions and norms of conduct which they find valuable. As such, its history reflects the struggle in society to assume, control or resist this authority. Its study should help to reveal the nature of the forces involved in the struggle and to suggest the implications for social development of the way in which, at any one time, their struggle was resolved. The condition of the law may be seen to crystallize the condition of society. This, of course, could be said of any governing institution. But where the law becomes uniquely valuable is in that, because of its social function, the struggle around it is necessarily expressed in terms of general statements of principle rather than particular statements of private and discrete interest. At the most fundamental level, these principles demarcate the rules on which the contending parties seek to build their versions of society and provide useful clues to their wider, often undisclosed, positions.
265 citations
TL;DR: Dynamics are introduced into Maynard Smith's game about the evolution of strategies in animal conflicts and the stabilised game offers an explanation for the development of hierarchical societies in terms of natural selection acting on individuals.
204 citations
185 citations
TL;DR: In this article, three asymptotically equivalent tests for the presence of a common factor in a spatial autoregression model are presented, and the model reduces to the simple regressions.
Abstract: Three asymptotically equivalent tests for the presence of a common factor in a spatial autoregression model are presented. When such a common factor exists, the model reduces to the simple regressi...
184 citations
TL;DR: Key links are established between the redox state of plastoquinone, the activation of protein kinase and changes in chlorophyll fluorescence and the relative rates of excitation of PSI1 and PSI is presented.
177 citations
TL;DR: In this paper, the authors discuss the relation between the following properties o finite measure preserving ergodic actions of a countable group G: strong ergodicity (i.e., the non-existence of almost invariant sets), uniqueness of G-invariant means, and certain cohomological properties.
Abstract: This paper discusses the relations between the following properties o finite measure preserving ergodic actions of a countable group G: strong ergodicity (i.e. the non-existence of almost invariant sets), uniqueness of G-invariant means on the measure space carrying the group action, and certain cohomological properties. Using these properties one can characterize all actions of amenable groups and of groups with Kazhdan's property T. For groups which fall in between these two definations these notions lead to some interesting examples.
TL;DR: In this article, the moisture content of surface soil from measurements of rainfall and daily maximum and minimum air temperatures was used to calculate soil temperatures, and the equations were incorporated into a simulation model for the prediction of herbicide persistence.
Abstract: Empirical equations were used to calculate the moisture content of surface soil from measurements of rainfall and daily maximum and minimum air temperatures. Air temperatures were also used to calculate soil temperatures. There was good agreement between calculated and measured moisture contents and temperatures from Wellesbourne and from some sites in North America. The equations were incorporated into a simulation model for the prediction of herbicide persistence. Results from the model were essentially the same, whether calculated or measured soil moistures and temperatures were used in the calculations.
TL;DR: No correlation was found between protein concentration and susceptibility to tobacco mosaic virus infection, measured either as lesion number or size, and the role of the “pathogenesis-related” proteins in acquired systemic resistance is questioned.
Abstract: Four host-coded “pathogenesis-related” proteins accumulate in local-lesion-forming varieties of tobacco after infection with tobacco mosaic virus. It has been suggested that they are involved in the acquired systemic resistance of plants to a second inoculation. It is shown that while these proteins were undetectable in leaves of young, healthy plants of the cv. Xanthi-nc., they did accumulate in large amounts when healthy plants flowered. Accumulation depended on the presence of both the developing inflorescence and the senescing lower leaves. The 2 commonest of these proteins from flowering, healthy plants were shown to behave identically to analogous proteins from young, infected plants on gel filtration, ion-exchange chromatography, and electrophoresis under denaturing and non-denaturing conditions. When healthy plants were experimentally treated so that they accumulated very different amounts of “pathogenesis-related” proteins, no correlation was found between protein concentration and susceptibility to tobacco mosaic virus infection, measured either as lesion number or size. The role of the “pathogenesis-related” proteins in acquired systemic resistance is therefore questioned.
TL;DR: For instance, this article pointed out that although there is an apparent consensus that ancient notions of poetic inspiration correspond in some way to modern ideas about the nature of poetic creativity, little attention has been paid to these modern notions of inspiration.
Abstract: It is generally agreed that the concept of inspiration is one of the most basic and persistent of Greek notions about poetry. Yet there appears to be a certain confusion on the significance of this observation. For instance, while most scholars consider that the idea is of very great antiquity in Greece, there is a recent tendency to regard the concept as a formulation of the fifth century B.C. E. A. Havelock, for example, describes the notion of poetic inspiration as an invention of fifth century philosophers, and G. S. Kirk states, without discussion, that poetic inspiration was ‘probably quite a new conception’ at the time Euripides was writing. This type of disagreement clearly relates to the more fundamental question of the meaning of the concept of inspiration itself. For although there is an apparent consensus that ancient notions of poetic inspiration correspond in some way to certain modern ideas about the nature of poetic creativity, little attention has been paid to these modern notions of inspiration. And unless such modern notions are investigated, the mere observation that there is a similarity is of little value.
TL;DR: This food eating pattern model should prove useful for examining the association between food consumption and the incidence of disease states, such as obesity, hypertension, cardiovascular disease, cancer, and periodontal disease for various large scale dietary-health surveys.
TL;DR: The use of symbolic sequences to study dynamical properties of geodesies originates in the work of Koebe [21, 22] and Morse [24, 25] and is already foreshadowed in Hadamard [15] and Jordan as mentioned in this paper.
Abstract: The subject of symbolic dynamics is of central importance in the modern theory of dynamical systems. The use of symbolic sequences to study dynamical properties of geodesies originates in the work of Koebe [21, 22] and Morse [24, 25] and is already foreshadowed in Hadamard [15] and Jordan [19]. The method of Koebe and of Morse is to code a geodesic on a surface M of negative curvature by recording the order in which it traverses a given set of labelled curves on M. The treatment of Morse allows variable curvature but assumes at least two boundary components, whereas Koebe assumes constant curvature but allows infinite connectivity and nonorientability and treats the more difficult case of a closed surface. This last case is handled by recording crossings of a fixed pants decomposition, anticipating the Thurston parameterization of simple curves as described in [11]. Both Koebe and Morse used their codings to demonstrate the existence of countably many closed geodesies and of everywhere dense (transitive) geodesies. Morse further constructed the first nonsynthetic example of a recurrent nonperiodic discontinuous motion (in modern terminology, a minimal nowhere dense set). Later [26] Morse treated the special closed surfaces of genus g associated to tesselations of the disc D by regular 4
TL;DR: A graph having 27 vertices is described, whose automorphism group is transitive on vertices and undirected edges, but not on directed edges.
Abstract: A graph having 27 vertices is described, whose automorphism group is transitive on vertices and undirected edges, but not on directed edges.
TL;DR: It is demonstrated that access to the endoplasmic reticulum but not glycosylation is a mandatory intermediate step in secretion, and the advantages of the oocyte as a surrogate system for the study of the later events in the gene expression pathway are emphasized.
Abstract: Secretory proteins made in Xenopus laevis oocytes under the direction of heterologous messenger RNA are modified, topologically segregated and exported. Thus the oocyte may serve as a useful surrogate secretory system and we have studied some of the factors governing access to the export pathway. Unglycosylated chicken ovalbumin, synthesized and trapped in the cytosol, is not secreted but glycosylated ovalbumin, found sequestered within vesicles, is exported from oocytes. However, ovalbumin, which is transferred across the endoplasmic reticulum in the presence of tunicamycin and which is indistinguishable by immunoprecipitation, by two-dimensional gel electrophoresis and by concanavalin-A—Sepharose binding from the cytosolic form, is still secreted. Guinea-pig milk proteins and human interferon are also exported from tunicamycin-treated frog cells. These observations demonstrate that access to the endoplasmic reticulum but not glycosylation is a mandatory intermediate step in secretion. and emphasize the advantages of the oocyte as a surrogate system for the study of the later events in the gene expression pathway.
TL;DR: In this article, a model for the formation of a gold-rich layer on the surface of a silver-gold and copper-gold alloys was proposed, where the surface becomes disordered by selective dissolution and then reorders by surface diffusion of the residual gold atoms.
Abstract: Electron microscope observations of the micromorphology of silver-gold and copper-gold alloys corroded in nitric acid and ferric chloride solutions demonstrate how the surfaces of these alloys become covered by a gold-rich layer following the selective dissolution of the less-noble component. The gold layer forms initially from island nuclei which grow and eventually merge to form a connected structure, enclosing channels and pits where the merger is incomplete. Observations on the kinetics of island growth suggest a model for this form of corrosion by which the surface of the alloy becomes disordered by selective dissolution and then reorders by surface diffusion of the residual gold atoms. Analysis of this model is used to discuss the morphology of islands and pits and the conditions under which the pits might transform into corrosion tunnels. Those results are discussed in relation to previous morphological studies of corrosion tunnelling. It is shown that the surface disordering-reordering mo...
TL;DR: For an Axiom A Diffeomorphism of a surface with an ergodic invariant measure, the entropy is the product of the positive Lyapunov exponent and the Hausdorff dimension of the set of generic points in an unstable manifold as mentioned in this paper.
Abstract: For an Axiom A diffeomorphism of a surface with an ergodic invariant measure we prove that the entropy is the product of the positive Lyapunov exponent and the Hausdorff dimension of the set of generic points in an unstable manifold.
01 Sep 1981
TL;DR: In this article, a brief introduction to the more common geometric structures is given, also showing their linear counterparts, and how these structures arise in systems theory by introducing the nonlinear control problems involved with mechanical manipulators, electrical networks, rotating electrical machinery and attitude control of spacecraft.
Abstract: The predominance of linear models in systems theory has tended to obscure the natural structure possessed by given nonlinear physical systems, either through linearisation, model order reduction, or choice of co-ordinates. The purpose of the paper is to motivate the reintroduction of geometric structure into systems theory. First, a brief introduction to the more common geometric structures is given, also showing their linear counterparts. It is then shown how these structures arise in systems theory by introducing the nonlinear control problems involved with mechanical manipulators, electrical networks, rotating electrical machinery and attitude control of spacecraft. The paper is concluded by considering the application of some of the geometric structures to nonlinear Hamiltonian and potential input/output systems.
TL;DR: In this paper, the free-boundary problem with allowance for surface tension is solved in a two-dimensional approximation by combined complex-variable and numerical methods in the cases where the far field is either uniform or of quadrupole form, or where the field is produced by four vertical conductors centred on the column.
Abstract: In continuous casting the vertically falling liquid column may be shaped by externally applied, horizontal, high-frequency magnetic fields. The free-boundary problem with allowance for surface tension is solved in a two-dimensional approximation by combined complex-variable and numerical methods in the cases where the far field is either uniform or of quadrupole form, or where the field is produced by four vertical conductors centred on the column. Stirring of the fluid is ignored.
TL;DR: A survey of the applications of catastrophe theory to the physical sciences can be found in this paper, where the authors confine attention to an area lying between "elementary" and "general" catastrophe theory, usually known as Singularity Theory.
TL;DR: In this article, the authors reported the results of experiments on 1 keV 4 He ion scattering from Ni {100, Ni { 100, Ni{100}(√2 × √2)R45°-O and Ni{ 100}(2 × 2)C surface structures using scattering angles of 48° and 90° Azimuthal anisotropies associated with structural shadowing are not explicable using purely elastic scattering arguments.
01 Feb 1981
TL;DR: In this article, Sampson and Schoen-Yau established a theorem concerning the dependence of harmonic maps on the Riomatmian metrics used to define them, based on the implicit function theorem in suitable manifolds of maps.
Abstract: In this paper we establish a theorem ((3.1) below) concerning the dependence of harmonic maps on the Riomatmian metrics used to define them. Our method is aa application of the implicit function theorem in suitable manifolds of maps. In the case of a compact range of negative curvature, that result was obtained by Sampson [24], usir, g derivative estimates for harmonic maps given in [10]. Another special case has been found by Schoen-Yau [2@ and applied by them to obtain theorem (6.3) below. Their proof is entirely different; it is based on a Diricblet growth theorem of Morrey ([21] lemma 9.4.18) and thus is restricted to maps with two-dimensional domains. In some cases the geometry of the problem introduces irrelevant degeneracy. For instance, that can happen it" M or N has a nontrivial group of isometrics-or ff the harmonic map under consideration factorises through a geodesic. More technical results concerning some of those cases are given in w 5. As applications, we offer proofs of two theorems on harmonic diffeomorphisms of surfaces, duo to Sampson [24] and Schoen-Yau [26]. We are much indebted to Professor Saxnpson for mzay stimulating conversations, as well as for making available to us (many years ago) a preliminary version of his manuscript [24]--a primary source of motivation for the present work.
TL;DR: The numbers of seedlings were greatest in the first year and thereafter decreased approximately exponentially from year to year, except for C. segetum and A. cotula, in which there was evidence of innate dormancy imposed by the seed coat.
Abstract: SUMMARY
Achenes of 12 species of Compositae were collected in each of 3 years and mixed with the top 7.5 cm of sterilised soil which was confined in cylinders sunk in the ground outdoors and cultivated three times yearly. Seedling emergence was recorded for 5 yr and the numbers of viable seeds remaining then determined. Emergence of Arctium lappa, A. minus, Picris hieracioides, Taraxacum officinale, Sonchus arvensis and S. asper was mainly in spring. Seedlings of Chrysanthemum segetum, Lapsana communis, Anthemis cotula and Sonchus oleraceus were often most numerous in spring but also emerged at other times, while Matricaria matricarioides and M. recutita showed no consistent seasonal pattern of emergence. Except for C. segetum and A. cotula, in which there was evidence of innate dormancy imposed by the seed coat, the numbers of seedlings were greatest in the first year and thereafter decreased approximately exponentially from year to year. Few viable seeds of A. lappa or A. minus remained after 5 yr and those of T. officinale, P. hieracioides and S. arvensis accounted for less than 1.5% of the seeds sown. Seed survival was greatest in the annual weeds and ranged from 2.1% (S. asper) to 8.6% (M. matricarioides) after 5 yr.
TL;DR: In this paper, it was shown that tetramethyl-p-benzoquinone (TMQ) is an electron donor in isolated chloroplasts and the resulting electron transport is highly sensitive to inhibition by DBMIB, and the site of donation is inferred to be plastoquinone.