Showing papers by "University of Sussex published in 1984"
TL;DR: In this article, the authors describe and explain sectoral patterns of technical change as revealed by data on about 2000 significant innovations in Britain since 1945, which can be explained by sources of technology, requirements of users, and possibilities for appropriation.
5,749 citations
TL;DR: In this paper, the basic physical processes involved in the nucleation and growth of thin films of materials on solid surfaces are described, and the relationships between the thermodynamics of adsorption and the kinetics of crystal growth are explored in general terms.
Abstract: The purpose of this article is to describe the basic physical processes involved in the nucleation and growth of thin films of materials on solid surfaces. In this introduction the three modes of crystal growth which are thought to occur on surfaces in the absence of interdiffusion are described, and the relationships between the thermodynamics of adsorption and the kinetics of crystal growth are explored in general terms. This is followed by a brief review of atomistic nucleation theory, explaining the relations of such theories to experimental observables. In the next three sections, recent experimental examples of these three growth modes are given, which are interpreted where possible in terms of nucleation and growth theory. The last section discusses observations on the shapes of growing crystallites and the relation of such observations to nucleation and surface diffusion processes.
2,456 citations
Book•
22 Mar 1984TL;DR: Presents a review of graph theory, analyzing the existing links between abstract theoretical results and their practical implications using graph theoretical models and combinatorial algorithms.
Abstract: Presents a review of graph theory, analyzing the existing links between abstract theoretical results and their practical implications using graph theoretical models and combinatorial algorithms. Includes extensive examples to illustrate the mathematical concepts when introduced. Treats subjects often excluded in other texts such as path algebra flow with grains, multicommodity flows, and the analysis and design of approximate algorithms.
749 citations
TL;DR: In this article, the derivation of gap equations and Ginzburg-Landau free energies for relativistic fermion systems is reviewed and the cases of superfluid neutron matter, superconducting electrons and superconducted and colour super-conducting quark matter are described in detail.
494 citations
TL;DR: Tentative preliminaire de developpement d'une theorie (basee sur l'hypothese de la «Red Queen», sur la theorie de the biogeographie des iles et sur d'autres concepts) sur le comportement a long terme des ecosystemes.
Abstract: Tentative preliminaire de developpement d'une theorie (basee sur l'hypothese de la «Red Queen», sur la theorie de la biogeographie des iles et sur d'autres concepts) sur le comportement a long terme des ecosystemes, comprenant des changements dans le nombre d'especes, leur constitution genetique et leur abondance relative
296 citations
TL;DR: This paper investigated 7-8 year-olds' use of implicit inferences in understanding stories and found that skilled readers were better than less skilled readers at answering questions from memory shortly after reading a story, both when the questions could be answered directly from the text, and when they required an inference.
Abstract: Summary An experiment was carried out to investigate 7–8 year-olds' use of implicit inferences in understanding stories Two groups of children, differentiated by their ability at text comprehension, read four short stories and were asked a series of questions after each one The results showed that skilled readers were better than less skilled readers at answering questions from memory shortly after reading a story, both when the questions could be answered directly from the text, and when they required an inference However, when the text was made available, the less skilled group remained poorer at answering questions that required an inference, although their performance on literal questions improved to the same level as that of the skilled group Thus, the experiment supports the idea that a major distinguishing characteristic of skilled readers is that they are good at making inferences, which enable them to relate the ideas in a text one to another and to general knowledge Additionally, the results provide no support for the claim that differences in ability to make inferences can be attributed to differences in memory for prose: the less skilled group were poorer at making inferences even when the text was available to them
275 citations
TL;DR: It is concluded that inbreeding avoidance is generally important in the evolution of dioecy, though reallocation of reproductive resources is also necessary.
Abstract: The likelihood that dioecy could evolve via androdioecy is examined. It is concluded that female-sterility mutations are unlikely to be able to invade populations of self-compatible hermaphrodite species, even if the resources that an hermaphrodite devotes to seed production can be diverted to yield increased survival and also to increase male fertility. These findings are in agreement with the great rarity of androdioecy. Claimed cases of androdioecy are reviewed. All of the species in question appear to be functionally dioecious, with females retaining substantial anther vestiges. It is argued that this morphological androdioecy is in no way indicative of a previous functionally androdioecious state. The details of the reproductive biology of many of these species seem rather to be consistent with their having evolved dioecy via gynodioecy.
The rarity of androdioecy, as a route to the evolution of dioecy, suggests that re-allocation of reproductive resources is unlikely to be the sole factor of importance, and supports an important role for inbreeding avoidance. The fact that females in some dioecious species retain anthers of substantial size, containing considerable quantities of pollen, gives further support to the view that male-sterility mutations can sometimes be favoured even when little or no resources are re-allocated to male functions. This is impossible without substantial selfing and inbreeding. It is therefore concluded that inbreeding avoidance is generally important in the evolution of dioecy, though reallocation of reproductive resources is also necessary.
270 citations
TL;DR: This chapter focuses on nuclear ADP-ribosyl transferase, which regulates DNA ligation in DNA repair and in other DNA rearrangements, such as DNA recombination, gene rearrangement, transpositions, sister chromatid exchanges, and chromosomal aberrations.
Abstract: Publisher Summary This chapter focuses on ADP-ribose in DNA repair. The fact that (ADP-ribose) n biosynthesis is required for efficient DNA repair rests on a large variety of observations. All DNA-damaging agents lower cellular NAD because they promote the biosynthesis of (ADP-ribose) n . DNA-damaging agents increase intracellular (ADP-ribose) n . Nuclear ADP-ribosyl transferase is activated by both single- and double-strand breaks in the DNA. All the inhibitors of nuclear ADP-ribosyl transferase prevent the drop in cellular NAD caused by DNA-damaging agents. All the enzyme inhibitors also inhibit DNA excision repair after both chemical and radiation damage. Alkylation damage increases DNA ligase activity, and it is predominantly DNA ligase II activity that is increased. One function of (ADP-ribose) n in DNA repair is in regulating DNA ligase II activity. Nuclear ADP-ribosyl transferase activity is activated by breaks in the DNA, and ADP-ribosylation, in turn, regulates DNA ligase II activity. Nuclear ADP-ribosyl transferase regulates DNA ligation in DNA repair and in other DNA rearrangements, such as DNA recombination, gene rearrangements, transpositions, sister chromatid exchanges, and chromosomal aberrations.
225 citations
TL;DR: In this paper, it was shown that the optic flow field arising from motion relative to a visually textured plane may be characterized by eight parameters that depend on the observer's linear and angular velocity and the coordinate vector of the plane.
Abstract: It is shown that the optic flow field arising from motion relative to a visually textured plane may be characterized by eight parameters that depend on the observer's linear and angular velocity and the coordinate vector of the plane. These three vectors are not, however, uniquely determined by the values of the eight parameters. First, the optic flow field does not supply independent values for the observer's speed and distance from the plane; it only gives the ratio of these two quantities. But more unexpectedly, the equations relating the observer's linear velocity and the plane's coordinate vector to the eight parameters are still satisfied if the two vectors are interchanged or reversed in direction, or both. So in addition to the veridical interpretation of the optic flow field there exist three spurious interpretations to be considered and if possible excluded. This purpose is served by the condition that an interpretation can be seriously entertained only if it attributes every image element to a light source in the observer's field of view. This condition immediately eliminates one of the spurious interpretations, and exhibits the other two as mutually inconsistent: one of them is tenable only if all the visible sources lie on the forward half of the plane (relative to the observer's linear velocity); the other only if they all lie on the backward half-plane. If the sources are distributed over both halves of the plane, only the veridical interpretation survives. Its computation involves solving a 3 $\times $ 3 eigenvalue problem derived from the flow field. If the upper two eigenvalues coincide, the observer must be moving directly towards the plane; if the lower two eigenvalues coincide, his motion must be directly away from it; in both cases the spurious interpretation merges with the veridical one. If all three eigenvalues are equal, it may be inferred that either the observer's linear velocity vanishes or the plane is infinitely distant.
216 citations
TL;DR: In evolutionary game theory, the fitness of a particular phenotype depends on its frequency in the population as mentioned in this paper, which is a method of analysing the evolution of phenotypes (including types of behaviour) when individuals are competing against the population as a whole or some part of it.
Abstract: Evolutionary game theory is a method of analysing the evolution of phenotypes (including types of behaviour) when the fitness of a particular phenotype depends onits frequency in the population. It was first applied to pairwise contests between animals. Such contests usually have some associated asymmetry, in size, prior residence, or age or sex status; the theory predicts that the asymmetry will be used as a cue to settlethe contest, and this is found to be the case. The theory can also be applied when individuals are competing against the population as a whole, or some part of it. In such cases, the evolution of variable behaviour - so-called mixed strategies - is predicted; actual examples of this are given. Game theory can be applied to the evolution of cooperative as well as of antagonistic behaviour. An analysis of the evolution of learning leads to testable predictions about learning behaviour.
184 citations
TL;DR: High-specific-activity single-stranded (ss) [alpha-32P]DNA of a defined size complementary to sequences cloned into bacteriophage M13 is synthesized, which is up to 300 times more sensitive than conventional S1 mapping techniques.
TL;DR: Newman as mentioned in this paper showed that NGC 4151 and 3C 390.3 sont tres proches of Seyfert II, i.e. the source of the universe.
Abstract: Les premiers spectres obtenus avec le nouveau Telescope Isaac Newton montrent que NGC 4151 et 3C 390.3 sont tres proches des Seyfert II. On propose que les galaxies de Seyfert II sont des Seyfert I dans lesquelles la source du continuum est temporairement eteinte
TL;DR: In this paper, a new class of exact inhomogeneous solutions to Einstein's equations with non-zero cosmological constant and zero pressure was given, which generalize the de Sitter space-time and evolve towards a state that is stationary inside the event horizon of any future inextendible time-like curve and confirm the cosmic no hair conjecture.
TL;DR: Eight Nif− mutants of Azospirillum brasilense were obtained by N-nitrosoguanidine mutagenesis and isolated by growth on glutamate medium and evidence will be presented that one of these mutants is defective in a nifA type regulatory gene.
Abstract: Eight Nif− mutants of Azospirillum brasilense were obtained by N-nitrosoguanidine mutagenesis and isolated by growth on glutamate medium. Three of these mutants had no nitrogenase activity, possessed no nitrogenase structural proteins and were complemented by Klebsiella pneumoniae nifA. Evidence will be presented that one of these mutants is defective in a nifA type regulatory gene but the other two were also complemented by K. pneumoniae ntrC and may be ntrC−-type mutants. A fourth mutant was defective in the MoFe component protein of nitrogenase.
TL;DR: On applique la methode a la fonction de correlation angulaire a deux points du catalogue de galaxies de 14 mag de Zwicky as discussed by the authors, on trouve des erreurs standards de σ(θ 0 )=0,01 and σ (γ)=0,13 avec des moyennes de γ= 0,80 and θ 0 =0,06 radians.
Abstract: On applique la methode a la fonction de correlation angulaire a deux points du catalogue de galaxies de 14 mag de Zwicky. Si la fonction a deux points est de la forme ω(θ)=(θ 0 /θ)γ, on trouve des erreurs standards de σ(θ 0 )=0,01 et σ(γ)=0,13 avec des moyennes de γ=0,80 et θ 0 =0,06 radians
TL;DR: In this paper, the role of small firms in the diffusion of new technologies is discussed, specifically semiconductors and computer aided design (CAD), and the authors demonstrate the interrelationship between the two.
Abstract: It is clear from research policy statements throughout Europe and in the USA and Japan that governments are becoming increasingly interested in the well-being of small firms. This is based on a belief in their ability to generate employment, their potential for the industrial regeneration of the so-called development areas and their ability to produce technological innovations. It is to this latter issue—the innovation potential of small firms—that this article is addressed. Further, while most studies of the role of small firms in innovation have been concerned with ‘innovation counts’ and have adopted a rather static approach, we are here concerned with their role in the dynamics of the introduction and diffusion of new technologies, specifically semiconductors and computer aided design (CAD). Moreover, there has in the past been a tendency to emphasize the role of the small firms or the role of large firms in innovation; we reject this rather sterile view and demonstrate the interrelationship between the two. In both areas—semiconductors and CAD—the initial breakthroughs were made in the RD it was through the actions of new technology-based small firms that these innovations were diffused into more general use. Again in both cases, the basic technological know-how, the entrepreneurs themselves and often the risk capital, derived from the original innovating large companies. Thus, policies that do not take into account the dynamic complementarities between the large and the small clearly are of only limited utility.
TL;DR: In this paper, the addition of triethylsilane to phenylacetylene or diphenyl-acetylene, catalysed by cis-[RhCl(COD)LMe] or trans-[Rhodium(PPh3)2LMe], proceeds stereoselectively via trans-addition.
TL;DR: Six experiments investigated the effects of pre-exposure to a tone on the subsequent acquisition of conditioned suppression by rats, and cast doubt upon Wagner's (1976, 1979) theory of the role of contextual factors in latent inhibition.
Abstract: Six experiments investigated the effects of pre-exposure to a tone on the subsequent acquisition of conditioned suppression by rats. In Experiments 1–3 the response suppressed was drinking; in Experiments 4–6 it was food-rewarded lever pressing. Repeated exposure to the tone resulted in latent inhibition, i.e., a retardation in the acquisition of suppression. The size of the latent inhibition effect was reduced when a different context was used for conditioning from that used for pre-exposure (Experiment 2). When the context remained the same throughout, a phase of exposure to the context alone, interposed between pre-exposure and conditioning, had no influence on the size of the latent inhibition effect ultimately observed. This last result casts doubt upon Wagner's (1976, 1979) theory of the role of contextual factors in latent inhibition, and alternative accounts are considered.
TL;DR: The range of differences found suggest that temporal lobe and diencephalic amnesics should not be considered as suffering from the same type of "amnesic syndrome".
TL;DR: In this paper, the effect of tungsten and carbon additions on the lattice parameter, crystallographic structure, magnetic saturation, and tensile properties of cobalt alloys was investigated.
TL;DR: High resolution S1 mapping of in vivo transcripts indicates that the regulatory region upstream of the glnA gene contains tandem promoters separated by 100 nucleotides, which resembles the consensus sequence for E. coli promoters, whereas the downstream promoter shows homology with the nitrogen fixation (nif) promoters of K. pneumoniae.
Abstract: Transcription of the structural gene for glutamine synthetase (glnA) in Klebsiella pneumoniae is controlled by the nitrogen regulatory genes ntrA, ntrB and ntrC. The nucleotide sequence of the regulatory region upstream of the glnA gene is reported here. High resolution S1 mapping of in vivo transcripts indicates that the regulatory region contains tandem promoters separated by 100 nucleotides. Measurements of beta-galactosidase activities determined in vivo from glnA-lac fusions suggest that the upstream promoter (for RNA2) is negatively regulated by the ntrBC gene products whereas transcription from the downstream promoter (for RNA1) is positively activated by the ntrA gene product in the presence of either the ntrBC or the nifA genes. The nucleotide sequence of the upstream promoter resembles the consensus sequence for E. coli promoters, whereas the downstream promoter shows homology with the nitrogen fixation (nif) promoters of K. pneumoniae.
TL;DR: In this paper, the growth of Ag on Si(100)2 × 1 and Si(111)7 × 7 surfaces has been examined as a function of deposition time and substrate temperature, using an ultra high vacuum-scanning electron microscope (UHV-SEM), equipped with micro-Auger electron spectroscopy and RHEED.
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TL;DR: The authors argued that urban bias is the moving force behind needlessly slow and inequitable growth in contemporary developing countries and defended this claim against three main criticisms: that the methods chosen to test it are not appropriate; that the evidence tendered is not relevant or sufficient; and that the rural-urban polarity is not clear-cut or does not represent the prime conflict within contemporary developing country.
Abstract: In his book ‘Why Poor People Stay Poor'the author has argued that urban bias is the moving force behind needlessly slow and inequitable growth in contemporary developing countries. This claim is defended against three main criticisms: that the methods chosen to test it are not appropriate; that the evidence tendered is not relevant or sufficient; and that the rural‐urban polarity is not clear‐cut or does not represent the prime conflict within contemporary developing countries.
TL;DR: In this article, the authors used a two-tendency model to simulate web-sites in the Agelenopsis aperta, where the next act of a spider is determined by the value of two "drives" or "tendencies", to attack and to flee.
TL;DR: In this article, the authors demonstrate that some perceptual grouping operations are performed before the first formant of a vowel is estimated from the amplitudes of its component harmonics, and that the small contribution to vowel quality of a harmonic that starts before a vowel can be increased by adding an additional tone that will in turn form a perceptual group with that part of the harmonic preceding the vowel.
Abstract: When one harmonic of a vowel starts before and stops after the others, its contribution to the vowel's phonetic quality is reduced. Two experiments demonstrate that this reduction cannot be attributed entirely to adaptation. The first experiment shows that a harmonic that starts at the same time as a short vowel but continues after the vowel has ended contributes almost as little to the vowel's phonetic quality as a harmonic that starts before but stops at the same time as the vowel. The second experiment shows that the small contribution to vowel quality of a harmonic that starts before a vowel can be increased by adding an additional tone that will in turn form a perceptual group with that part of the harmonic preceding the vowel. The experiments demonstrate that some perceptual grouping operations are performed before the first formant of a vowel is estimated from the amplitudes of its component harmonics.
TL;DR: This paper examined whether such phonological effects can be used in speech perception as cues to syntactic structure, and the relation between the use of these segmental features as syntactic markers in production and perception.
TL;DR: In this article, it is suggested that base pair errors can be made opposite sites of pyrimidine dimers without involvement of umuC gene product but that the latter is required for continued replication past the dimermismatch region.
Abstract: Bacteria of strain TK610 uvrA-6 his-4 umuC-36, when allowed to replicate their DNA for some hours after irradiation show induction of His+ mutations when subsequently exposed to visible light. It is suggested that base pair errors can be made opposite sites of pyrimidine dimers without involvement of umuC gene product but that the latter is required for continued replication past the dimermismatch region. Removal of the pyrimidine dimer by photoreversal allows replication to continue thus fixing the mismatched base as as mutation.
TL;DR: In this paper, water-deprived rats were allowed to drink in an experimental chamber during a series of training trials, and were then presented with an empty water spout during a single test trial.