Showing papers by "University of Sussex published in 1990"
TL;DR: Overall performance (survival) can be used to evaluate the salt resistance of a genotype, but it is not the basis on which parents should be selected to construct a complex character through breeding.
Abstract: Phenotypic resistance of salinity is expressed as the ability to survive and grow in a salinised medium. Some subjective measure of overall performance has normally been used in plant breeding programmes aimed at increasing salinity resistance, not only to evaluate progeny, but to select parents. Salinity resistance has, at least implicitly, been treated as a single trait. Physiological studies of rice suggest that a range of characteristics (such as low shoot sodium concentration, compartmentation of salt in older rather than younger leaves, tolerance to salt within leaves and plant vigour) would increase the ability of the plant to cope with salinity. We describe the screening of a large number of rice genotypes for overall performance (using an objective measure based on survival) and for the aforementioned physiological traits. There was wide variation in all the characters studied, but only vigour was strongly correlated with survival. Shoot sodium concentration, which a priori is expected to be important, accounted for only a small proportion of the variability in the survival of salinity. Tissue tolerance (the cellular component of resistance reflecting the ability to compartmentalise salt within leaves) revealed a fivefold range between genotypes in the tolerance of their leaves to salt, but this was not correlated positively with survival. On the basis of such (lack of) correlation, these traits would be rejected in normal plant breeding practice, but we discuss the fallacies involved in attempting correlation between individual traits and the overall performance of a salt-sensitive species in saline conditions. We conclude that whilst overall performance (survival) can be used to evaluate the salt resistance of a genotype, it is not the basis on which parents should be selected to construct a complex character through breeding. It was the norm for varieties which had one good characteristic affecting salt resistance to be unexceptional or poor in the others. This constitutes experimental evidence that the potential for salt resistance present in the rice genome has not been realised in genotypes currently extant. The results are discussed in relation to the use of physiological traits in plant breeding, with particular reference to environmental stresses that do not affect a significant part of a species' ecological range.
404 citations
TL;DR: Findings are interpreted as providing further support for the idea that recognition memory entails two distinct components, one based on associative and contextual information, the other based on a “traceless” awareness of familiarity.
Abstract: The functional relation between recognition memory and conscious awareness was assessed in an experiment in which undivided attention at study was compared with two divided attention conditions, one more demanding than the other. When recognizing a word from the study list, subjects indicated whether they could consciously recollect its prior occurrence or recognized it on some other basis, in the absence of conscious recollection. Divided attention at study progressively impaired word recognition accompanied by conscious recollection. Recognition in the absence of conscious recollection was not affected by divided attention. These findings are interpreted as providing further support for the idea that recognition memory entails two distinct components, one based on associative and contextual information, the other based on a "traceless" awareness of familiarity.
382 citations
TL;DR: An L‐arginine‐dependent nitric oxide generating mechanism is involved in the inhibition of insulin secretion by IL‐1β, and accounts for the phenomenon of synergism between IL‐ 1β and TNF‐α.
372 citations
TL;DR: The results suggest that, with low levels of stimulation, ADP measurements could form the basis of an objective measure of cochlear function in human subjects.
Abstract: The acoustic intermodulation distortion product 2f1-f2 (ADP) was measured in human subjects to investigate (1) the dependence of ADP level on stimulus parameters and (2) the relationship between ADP level and auditory sensitivity. The frequency ratio (f2/f1), at which ADP level is maximal, varies only slightly across frequency and subjects. The average optimal ratio is 1.225. Beyond the maximum, the ADP level declines with increasing f2/f1 ratio, at rates of up to 250 dB/oct. As the level of one stimulus is increased relative to the other, the ADP grows, saturates, and in most cases shows a bendover. Maximum distortion is generated when L 1 exceeds L 2. Growth rate and saturation point are dependent on which stimulus is incremented and on the level of the stationary stimulus. With optimal stimulus parameters (levels below 60 dB SPL; L 1 greater than L 2 by 15 dB; f2/f1 = 1.225), ADP levels are commonly 30 dB below L 2. Patterns of ADP level across frequency vary between subjects, but are repeatable within each subject. As the frequency of one or both of the stimuli is varied, changes in ADP level exhibit a broadly featured pattern with a fine structure superimposed upon it. This fine structure was compared with the features in the stimulus frequency emission spectrum in one subject. With appropriate stimulus parameters, half of our subjects show a statistically significant correlation across frequency, between ADP level and auditory sensitivity at the corresponding f1 frequency. Our results suggest that, with low levels of stimulation, ADP measurements could form the basis of an objective measure of cochlear function in human subjects.
359 citations
TL;DR: A synthetic gene encoding horseradish peroxidase isoenzyme C has been synthesized and expressed in Escherichia coli and Ca2+ appears to play a key role in folding to give the active enzyme.
271 citations
237 citations
237 citations
TL;DR: In this paper, the role of heavy group 14 element carbene analogues in transition metal (M') chemistry is discussed, and the role and role of the 14 element analogues is discussed.
234 citations
TL;DR: In this paper, the authors used data from two recent surveys on innovation diffusion in Italian manufacturing industry to show that informal research is an important part of the total R&D undertaken by small and medium sized firms.
Abstract: On the basis of data from two recent surveys on innovation diffusion in Italian manufacturing industry, this paper shows that informal R&D is an important part of the total R&D undertaken by small and medium sized firms. Nevertheless, when an output indicator such as the number and the nature of the innovations introduced by firms of different size is used, it emerges that small firms have introduced mainly incremental rather than major innovations. The paper therefore suggests that systematic R&D undertaken by large firms within structured laboratories is more effective (in terms of product innovations) than occasional R&D carried out by small firms.
225 citations
TL;DR: In this paper, the authors distinguished Neo-Schumpeterian, world system, and regulation approaches to the analysis of structural change in advanced capitalist societies and developed theories of regulation and world system.
Abstract: Neo-Schumpeterian, world system, and regulation approaches to the analysis of structural change in advanced capitalist societies are distinguished and the development of theories of regulation and ...
TL;DR: Penicillin resistance in S. oralis has also probably arisen by horizontal transfer of this variant form of the class B mosaic PBP2B gene from a penicillin-resistant strain of S. pneumoniae.
Abstract: Penicillin-resistant strains of Streptococcus pneumoniae possess altered forms of penicillin-binding proteins (PBPs) with decreased affinity for penicillin The PBP2B genes of these strains have a mosaic structure, consisting of regions that are very similar to those in penicillin-sensitive strains, alternating with regions that are highly diverged Penicillin-resistant strains of viridans groups streptococci (eg, S sanguis and S oralis) that produce altered PBPs have also been reported The PBP2B genes of two penicillin-resistant clinical isolates of S sanguis were identical in sequence to the mosaic class B PBP2B genes found in penicillin-resistant serotype 23 strains of S pneumoniae Emergence of penicillin resistance appears to have occurred by the horizontal transfer of an altered PBP2B gene from penicillin-resistant S pneumoniae into S sanguis The PBP2B genes of three penicillin-resistant S oralis strains were similar to the mosaic class B PBP2B gene of penicillin-resistant strains of S pneumoniae but possessed an additional block of diverged sequence Penicillin resistance in S oralis has also probably arisen by horizontal transfer of this variant form of the class B mosaic PBP2B gene from a penicillin-resistant strain of S pneumoniae
Journal Article•
TL;DR: Access to contemporary cell biological techniques makes imaginal discs a model system for investigating patterning in animal tissues, and molecular genetic analysis of mutants with changed pattern has implicated transcription factors, secreted, membrane-bound and growth factor related proteins in the position-signalling mechanism.
TL;DR: The behavior of isotropic models in the general scalar-tensor theory of gravitation was investigated in this article. And the criterion for inflation to occur in a range of such theories, including that of Brans and Dicke, was derived.
Book•
01 Aug 1990TL;DR: This book is based on a course given to second-year computer science undergraduates at the University of Sussex in the spring of 1988 and 1989 and offers an elementary introduction to the semantics of programming languages in a form which is designed to be accessible to students who are not very advanced in their undergraduate career.
Abstract: This book is based on a course given to second-year computer science undergraduates at the University of Sussex in the spring of 1988 and 1989. It offers an elementary introduction to the semantics of programming languages in a form which is designed to be accessible to students who are not very advanced in their undergraduate career. All the material in the book may easily be covered in a one-term course. There are very few prerequisites. Students who have undertaken an introductory programming course and who are familiar with elementary mathematical notation should have little difficulty in following it. A first course in discrete mathematics would be more than sufficient to cover the required background material.
TL;DR: In this article, the impact of financial structures on industrial dynamics was investigated and it was argued that specific financial set-ups -such as market-based and credit-based mechanisms of allocation, control and ownership transfer - are likely to exert different influences on the rates and modes of industrial innovation.
Abstract: This paper investigates the impact financial structures upon industrial dynamics whenever the system is permanently characterized by unexploited opportunities for innovation, (highly) ‘bounded’ rationality and trial-and-error search processes. In these circumstances, it is argued, specific financial set-ups - such as ‘market-based’ vs. ‘credit-based’ mechanisms of allocation, control and ownership transfer - are likely to exert different influences on the rates and modes of industrial innovation. Relatedly, one suggests some hypotheses on the links between financial systems and features of industrial evolution, and some tentative taxonomies.
Proceedings Article•
29 Jul 1990TL;DR: Degrees of freedom analysis has significant computational advantages over conventional algebraic approaches and is demonstrated with a program that assembles and kinematically simulates mechanical linkages.
Abstract: Finding the configurations of a set of rigid bodies that satisfy a set of geometric constraints is a problem traditionally solved by reformulating the geometry and constraints as algebraic equations which are solved symbolically or numerically But many such problems can be solved by rea soning symbolically about the geometric bodies themselves using a new technique called degrees of freedom analysis In this approach, a sequence of actions is devised to satisfy each constraint incrementally, thus monotonically decreasing the system's remaining degrees of freedom This sequence of actions is used metaphorically to solve, in a maximally decoupled form, the equations resulting from an algebraic representation of the problem Degrees of freedom analysis has significant computational advantages over conventional algebraic approaches The utility of the technique is demonstrated with a program that assembles and kinematically simulates mechanical linkages
TL;DR: Comparative static results are reported indicating the effects on the demand for medical care of both increases in the means of these distributions and mean-preserving spreads of the distributions.
TL;DR: It is proposed that the patched product is a component of a cell-to-cell position-signalling mechanism, a proposal consistent with the predicted structure of the patched protein.
Abstract: We demonstrate the role of the segment polarity gene patched (ptc) in patterning in the cuticle of the adult fly. Genetic mosaics of a lethal allele of patched show that the contribution of patched varies in a position-specific manner, defining three regions in the wing where ptc clones, respectively, behave as wild-type cells, affect vein formation, or are rarely recovered. Analysis of twin clones demonstrates that the reduced clone frequency results from a proliferation failure or cell loss. In the region where clones upset venation, they autonomously fail to form veins and also non-autonomously induce ectopic veins in adjacent wild-type cells. In heteroallelic combinations with lethal alleles, two viable alleles produce distinct phenotypes: (1) loss of structures and mirror-image duplications in the region where patched clones fail to proliferate; (2) vein abnormalities in the anterior compartment. We propose that these differences reflect independently mutable functions within the gene. We show the pattern of patched transcription in the developing imaginal wing disc in relation to the expression of certain other reporter genes using a novel double-labelling method combining non-radioactive detection of in situ hybridization with beta-galactosidase detection. The patched transcript is present throughout the anterior compartment, with a stripe of maximal intensity along the A/P compartment border extending into the posterior compartment. We propose that the patched product is a component of a cell-to-cell position-signalling mechanism, a proposal consistent with the predicted structure of the patched protein.
TL;DR: In this article, a spectroscopie IR proche de 42 noyaux de galaxies normales et actives is presented and the triplet de Ca II is analyzed.
Abstract: La spectroscopie IR proche de 42 noyaux de galaxies normales et actives est presentee. Le triplet de Ca II est analyse. La force des raies de Ca II, les profils de luminosite et les dispersions de vitesse sont etudies
TL;DR: Two experiments provide further evidence that indicate two additional dimensions along which implicit and explicit memory differ and support recent conceptualizations of processing differences underlying these two forms of memory.
Abstract: In this article, we report two experiments that provide further evidence concerning the differential nature of implicit and explicit memory. In Experiment 1, subjects first undertook a sentence-verification task. While carrying out this task, half of the subjects were also required to carry out a secondary processing task involving tone monitoring. Twenty-four hours later, the subjects' memory for target items in the sentence-verification task was tested explicitly by means of a recognition task and implicitly by examining the extent to which the items primed fragment completion. Recognition performance was significantly impaired by the imposition of secondary processing demands during the original learning phase. In contrast, fragment completion was completely unaffected by this additional processing, even though substantial priming was observed. In Experiment 2, we examined whether priming in fragment completion is influenced by the nature of repetition during initial learning. Subjects studied a list of target items that were each repeated twice. Half the items were repeated immediately (lag 0) and half were repeated after six intervening items (lag 6). Memory for the items was assessed by recognition and by priming in fragment completion. Recognition was affected by lag, with lag 6 items being recognized better than lag 0 items. However, although significant priming was obtained, the extent of this priming was uninfluenced by lag. These data indicate two additional dimensions along which implicit and explicit memory differ and, furthermore, they support recent conceptualizations of processing differences underlying these two forms of memory.
01 Jan 1990
TL;DR: The use and potential of trees as a savings bank for the poor has been discussed in this article, where the authors present evidence and analysis on the use of trees for saving and security.
Abstract: Summary. - Professionals have rarely seen trees as savings banks for poor people. But while trees and their products have become more valuable and easier to market, many poor people have become more vulnerable as contingencies cost more and traditional supports weaken. Consequently, trees have increasing importance and potential as savings and security for the poor, and for use to meet contingencies. For savings and security, trees compare quite well with jewelry, large stock, small stock, land, and bank deposits. Disadvantages of trees can include insecure or unclear rights, restrictions on cutting and selling when needed, and problems with marketing; but common advantages include cheap and easy establishment, rapid appreciation in value, divisibility to meet needs closely, and regeneration after cutting. More empirical studies are needed on the use and potential of trees as poor people’s savings banks. The policy implications of present evidence and analysis include tree reform, improved marketing and prices, and above all investing poor people with secure and full ownership of trees, with rights to harvest, cut and sell similar lo the withdrawal rights of depositors in savings banks.
Journal Article•
TL;DR: Imaginal discs are sacs of folded epithelium arising during embryogenesis, and at metamorphosis secrete the adult cuticle, therefore being responsible for the characteristic surface patterning of this insect as discussed by the authors.
TL;DR: The enzyme TEM β‐lactamase constitutes a versatile gene‐fusion marker for studies on membrane proteins and protein export in bacteria and provides a useful alternative to alkaline phosphatase for probing the topology of cytoplasmic membrane proteins.
Abstract: The enzyme TEM beta-lactamase constitutes a versatile gene-fusion marker for studies on membrane proteins and protein export in bacteria. The mature form of this normally periplasmic enzyme displays readily detectable and distinctly different phenotypes when localized to the bacterial cytoplasm versus the periplasm, and thus provides a useful alternative to alkaline phosphatase for probing the topology of cytoplasmic membrane proteins. Cells producing translocated forms of beta-lactamase can be directly selected as ampicillin-resistant colonies, and consequently a beta-lactamase fusion approach can be used for positive selection for export signals, and for rapid assessment of whether any protein expressed in Escherichia coli inserts into the bacterial cytoplasmic membrane. The level of ampicillin resistance conferred on a cell by an extracytoplasmic beta-lactamase derivative depends on its level of expression, and therefore a beta-lactamase fusion approach can be used to directly select for increased yields of any periplasmic or membrane-bound gene products expressed in E. coli.
TL;DR: Nonmonotonic rate-level functions for tones at characteristic frequency were observed across all unit types classified by the post-stimulus time histogram scheme and an unexpected finding was a small number of primarylike units characterised by reduced driven discharge rates within their response areas.
TL;DR: In this paper, an analysis of the behavior of intermediate inflationary universes is given, which expand at a rate intermediate between that of power-law and exponential inflation, and no-hair theorems are proved for such inflationary universe in the presence of density, velocity and gravitational wave perturbations.
TL;DR: The striking tendency for life expectancy to be highest in those developed countries where income is distributed most equally, rather than in those which are richest, is starts out from the shape of the relationship between income and health which this implies within nations.
Abstract: This paper starts out from the striking tendency for life expectancy to be highest in those developed countries where income is distributed most equally, rather than in those which are richest It goes on to discuss the shape of the relationship between income and health which this implies within nations After reproducing evidence from the Health and Lifestyles Survey of a cross-sectional relationship in Britain which is consistent with the international picture, the paper then reports on a test of the causality of that relationship
The test compared the changes between 1971 and 1981 in the position of occupations in the‘earnings league’with changes in their position in the occupational mortality league in Britain The analysis found that changes in mortality were significantly, positively and independently related to changes in the proportion unemployed and the proportion on low relative earnings in each occupation The percentage change in the size of each occupational group during the decade was used to control for any effects of selection in or out of occupations The paper concludes with a brief discussion of the implications of these findings
01 Feb 1990-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: Ion implantation produces a variety of optical changes in insulators including major alterations of the refractive indices as mentioned in this paper, which are of major importance in the formation of low loss waveguide devices.
Abstract: Ion implantation produces a variety of optical changes in insulators including major alterations of the refractive indices. Consequently ion beam implantation has been used to form optical waveguides in a very diverse range of materials. These include key optoelectronic crystals, such as LiNbO 3 , Quartz, YAG. PLZT or BGO, amorphous glasses such as silica, and organics such as PMMA. Despite the generality of the technique there are major differences in the form of the index profiles. In particular the extraordinary and ordinary indices often behave differently. Electronic excitation and nuclear collision regions of the ion range can differ not only in the form. but also in the sign. of the index change. Further differences are noted in the subsequent thermal stability of these regions. Alternative mechanisms of defect formation, diffusion, stress and preferential surface decomposition are discussed and related to various examples of ion-implanted optical waveguides. The effects of these features are of major importance in the formation of low loss waveguide devices.
TL;DR: In this paper, a potential energy function for atomic solids consisting of two-body and three-body terms was proposed, which over its range of parameters encompasses all simple crystal structures.
Abstract: A potential energy function has been proposed for atomic solids consisting of two-body and three-body terms which over its range of parameters encompasses all simple crystal structures. Phase diagrams have been constructed as a function of a single parameter in the two-body term and one, of several, parameters in the three-body term, and these include as the most stable structures hcp, fcc, bcc, sc and diamond. The hcp and fcc lattices have been shown to distort to lower symmetries with appropriate three-body parameters and these distortions are in accord with known structures. A brief study has been made of the appropriate parameters for silicon.