Showing papers by "University of Sussex published in 1993"
TL;DR: In this article, the authors assess various organizational learning literatures by examining the insights they allow in three main areas: first, the goals of organizational learning; second, the learning processes in organizations; and third, the ways in which organizational learning may be facilitated and impeded.
Abstract: Organizational learning is currently the focus of considerable attention, and it is addressed by a broad range of literatures. Organization theory, industrial econ omics, economic history, and business, management and innovation studies all approach the question of how organizations learn. A number of branches of psychology are also revealing on the issue. This paper assesses these various literatures by examining the insights they allow in three main areas: first, the goals of organizational learning; second, the learning processes in organizations; and third, the ways in which organizational learning may be facilitated and impeded. It contends that while the various literatures are revealing in particular aspects of organizational learning, a more complete understanding of its complexity requires a multi-disciplinary approach. The contributions of the different approaches are analyzed, and some areas are suggested where the transfer of analytical concepts may improve understanding.
2,025 citations
TL;DR: Data from multilocus enzyme electrophoresis of bacterial populations were analyzed using a statistical test designed to detect associations between genes at different loci, and found panmictic, epidemic, and clonal population structures.
Abstract: Data from multilocus enzyme electrophoresis of bacterial populations were analyzed using a statistical test designed to detect associations between genes at different loci. Some species (e.g., Salmonella) were found to be clonal at all levels of analysis. At the other extreme, Neisseria gonorrhoeae is panmictic, with random association between loci. Two intermediate types of population structure were also found. Neisseria meningitidis displays what we have called an "epidemic" structure. There is significant association between loci, but this arises only because of the recent, explosive, increase in particular electrophoretic types; when this effect is eliminated the population is found to be effectively panmictic. In contrast, linkage disequilibrium in a population of Rhizobium meliloti exists because the sample consisted of two genetically isolated divisions, often fixed for different alleles: within each division association between loci was almost random. The method of analysis is appropriate whenever there is doubt about the extent of genetic recombination between members of a population. To illustrate this we analyzed data on protozoan parasites and again found panmictic, epidemic, and clonal population structures.
1,767 citations
TL;DR: The results of phase II of Project SAPPHO have been confirmed with the same five underlying factors emerging as strongly differentiating between success and failure and with some inter-industry differences becoming clearer.
895 citations
TL;DR: The development of the SCGE assay, existing protocols for the detection and analysis of comets, the relevant underlying principles determining the behaviour of DNA, and the potential applications of the technique are reviewed.
Abstract: The single cell gel electrophoresis (SCGE) assay is a rapid, simple, visual and sensitive technique for measuring DNA breakage in individual mammalian cells. Here we review the development of the SCGE assay (with particular reference to the alkaline version), existing protocols for the detection and analysis of comets, the relevant underlying principles determining the behaviour of DNA, and the potential applications of the technique.
894 citations
TL;DR: It is suggested that equality of health should be the dominant principle and that equity in health care should therefore entail distributing care in such a way as to get as close as is feasible to an equal distribution of health.
756 citations
01 May 1993
TL;DR: In this article, the analytical procedures for obtaining optimum PID controller settings for minimisation of time weighted integral performance criteria are reviewed and two procedures for finding the required controller parameters for optimisation of the integral of time error squared criterion are presented.
Abstract: The paper first briefly reviews the analytical procedures for obtaining optimum PID controller settings for minimisation of time weighted integral performance criteria. The approach is then used to obtain formulae for setting the controller parameters for a first-order plus dead time plant model which is a common approximation used in the process industries. These results are further extended to obtain two procedures, which can be used with the relay autotuning approach, to find the required controller parameters for optimisation of the integral of time error squared criterion. Good results have been obtained when these criteria are used with other plant models.
662 citations
TL;DR: In this article, the authors argue that the survival of such relationships in the face of these inevitable inter-personal problems requires the establishment of interorganizational trust, characterized by community of interest, organizational cultures receptive to external inputs, and widespread and continually supplemented knowledge among employees of the status and purpose of the collaboration.
Abstract: Companies increasingly collaborate in their technological activities. Collaboration enables firms to learn about uncertain and turbulent technological change, and enhances their ability to deal with novelty. A number of studies reveal the importance for successful collaboration of high levels of inter-personal trust between scientists, engineers, and managers in the different partners. However, these individual relationships are vulnerable to labor turnover and inter-personal difficulties. Using two examples of highly successful technological collaborations, it is argued that the survival of such relationships in the face of these inevitable inter-personal problems requires the establishment of interorganizational trust. Such trust is characterized by community of interest, organizational cultures receptive to external inputs, and widespread and continually supplemented knowledge among employees of the status and purpose of the collaboration.
595 citations
TL;DR: In this paper, a unified view of the CDM model is given, beginning with the creation of perturbations during an inflationary epoch and pursuing it right through to comparison with a host of observations.
570 citations
TL;DR: In this article, the structures of pyrolytic carbon nanotubes (PCNTs) produced by thermal decomposition of hydrocarbon vapor (benzene at ca 1100°C) have been studied.
461 citations
TL;DR: Evidence is provided for two distinct nonlymphoid-specific genes that encode factors involved in both DNA repair and V(D)J recombination in cells deficient in DNA repair.
Abstract: Cells maintain the integrity of their genome through an intricate network of repair systems that recognize and remove lesions from DNA. The only known site-directed recombination process in vertebrates is the V(D)J recombination of lymphocyte antigen receptor genes. A large panel of cell lines deficient in DNA repair were tested for the ability to perform V(D)J recombination after introduction of the RAG-1 and RAG-2 genes. Two mutants failed to generate normal V(D)J recombination, and further analysis provided evidence for two distinct nonlymphoid-specific genes that encode factors involved in both DNA repair and V(D)J recombination.
452 citations
TL;DR: Studies of the Sigma factor σ;54 (σN), encoded by rpoN, have demonstrated that this sigma is quite distinct both structurally and functionally from the �u;70 family and the mode of transcription initiation which it mediates may have more in common with that found in eukaryotes than that which occurs with �o;70 and its relatives.
Abstract: Bacteria synthesize a number of different sigma factors which allow the co-ordinate expression of groups of genes owing to the ability of sigma to confer promoter-specific transcription initiation on RNA polymerase. In nearly all cases these sigmas belong to a single family of proteins which appear to be related structurally and functionally to the major Escherichia coli sigma factor, sigma 70. A clear exception is the sigma factor sigma 54 (sigma N), encoded by rpoN, which represents a second family of sigmas that is widely distributed in prokaryotes. Studies of sigma 54 (sigma N) have demonstrated that this sigma is quite distinct both structurally and functionally from the sigma 70 family and the mode of transcription initiation which it mediates may have more in common with that found in eukaryotes than that which occurs with sigma 70 and its relatives.
TL;DR: Results demonstrate that robust visually guided control systems evolve from evaluation functions that do not explicitly require monitoring visual input, and propose an automatic design process involving artificial evolution, wherein the basic building blocks for evolving cognitive architectures are noise-tolerant dynamical neural networks.
Abstract: We discuss the methodological foundations for our work on the development of cognitive architectures, or control systems, for situated autonomous agents. Our focus is the problems of developing sen...
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01 Jan 1993TL;DR: The shoe industry of the Sinos Valley in Brazil has been investigated in this paper, where the authors investigate a success story from a country in crisis: the shoe industry in Brazil.
Abstract: This paper investigates a success story from a country in crisis: the shoe industry of the Sinos Valley in Brazil. The main question is to what extent the industrial district model captures the reality of the Sinos Valley. In many ways it does. The sectoral and geographical concentration of shoe manufacturers is formidable. Even more striking is the depth of the local economy which includes almost the entire range of supply industries and producer services. Collective action has also been significant in the development of the cluster but has changed over time; initially it was based on a common sociocultural identity, then it crumbled and its recent return is based on an economic rationale. Where model and reality differ most is in the strong presence of large firms. Most of these large firms, however, were small two decades ago. The inclusion of export agents is crucial to understand the radical transformation of this industrial cluster in a span of two decades. Indeed, some of the most interesting conclusions emerge from tracing changes over time.
TL;DR: Cronly-Dillon as mentioned in this paper described vision and visual dysfunction as a "vision and visual dysfunction" problem, and presented a treatment for it. 17 volumes. £1,250, $2,295.
Abstract: Vision and Visual Dysfunction. General editor: John Cronly-Dillon. Macmillan: 1991. 17 volumes. Approximately 5,000 pages. £1,250, $2,295.
TL;DR: In this article, the authors used strand specific probes to study the effect of the hereditary disease Cockayne's syndrome (CS) on the repair of lesions in active genes in normal cells.
Abstract: Removal of ultraviolet light induced cyclobutane pyrimidine dimers (CPD) from active and inactive genes was analyzed in cells derived from patients suffering from the hereditary disease Cockayne's syndrome (CS) using strand specific probes. The results indicate that the defect in CS cells affects two levels of repair of lesions in active genes. Firstly, CS cells are deficient in selective repair of the transcribed strand of active genes. In these cells the rate and efficiency of repair of CPD are equal for the transcribed and the nontranscribed strand of the active ADA and DHFR genes. In normal cells on the other hand, the transcribed strand of these genes is repaired faster than the nontranscribed strand. However, the nontranscribed strand is still repaired more efficiently than the inactive 754 gene and the gene coding for coagulation factor IX. Secondly, the repair level of active genes in CS cells exceeds that of inactive loci but is slower than the nontranscribed strand of active genes in normal cells. Our results support the model that CS cells lack a factor which is involved in targeting repair enzymes specifically towards DNA damage located in (potentially) active DNA.
TL;DR: This study shows that P BP2B genes from many penicillin‐resistant isolates of S. pneumoniae contain blocks of nucleotides originating from Streptococcus mitis, and in several instances it would appear that this material alone is sufficient to produce a low affinity PBP2B.
Abstract: Penicillin-resistant strains of Streptococcus pneumoniae possess forms of penicillin-binding proteins (PBPs) that have a low affinity for penicillin compared to those from penicillin-sensitive strains. PBP genes from penicillin-resistant isolates are very variable and have a mosaic structure composed of blocks of nucleotides that are similar to those found in PBP genes from penicillin-sensitive isolates and blocks that differ by up to 21%. These chromosomally encoded mosaic genes have presumably arisen following transformation and homologous recombination with PBP genes from a number of closely related species. This study shows that PBP2B genes from many penicillin-resistant isolates of S. pneumoniae contain blocks of nucleotides originating from Streptococcus mitis. In several instances it would appear that this material alone is sufficient to produce a low affinity PBP2B. In other examples PBP2B genes possess blocks of nucleotides from S. mitis and at least one additional unidentified species. Mosaic structure was also found in the PBP2B genes of penicillin-sensitive isolates of S. mitis or S. pneumoniae. These mosaics did not confer penicillin resistance but nevertheless reveal something of the extent to which localized recombination occurs in these naturally transformable streptococci.
TL;DR: Wingless activity is required at the presumptive wing margin and is a necessary precondition for the change in proliferation pattern in this region, and the time-course of this contribution and the effect on proneural gene expression together suggest that wingless may regulate the activity of products of the achaete-scute complex in proneural clusters.
Abstract: We have used conditional wingless genotypes to dissect the role of this gene in late stages of wing disc development. One of these genotypes (wgIL/wg-lacZ) is simultaneously a reporter of wingless transcription and temperature-sensitive for wingless function, and has allowed us to define its pattern of transcription in the absence of wingless activity. The primordia of a subset of the bristles of the notum, which develop in or immediately adjacent to wingless-expressing cells, depend upon wingless activity. The time-course of this contribution and the effect on proneural gene expression together suggest that wingless may regulate the activity of products of the achaete-scute complex in proneural clusters. wingless activity is also required at the presumptive wing margin and is a necessary precondition for the change in proliferation pattern in this region. The involvement of wingless in transducing or mediating positional signals for spatial patterning in imaginal disc development is discussed.
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01 Jan 1993TL;DR: In this article, the role of public and private institutions in the provision of credit, training of workers and entrepreneurs, provision of real services, and wage negotiations in industrial districts is examined.
Abstract: In the 1970s and 1980s, industrial districts in Europe achieved international competitiveness and attained high employment standards, even though they were based on local small- and medium-sized firms and concentrated on traditional sectors. This makes them of special interest to less-developed countries in the South and East. This paper examines what policy lessons can be drawn from this European experience. It does so by focusing on the role of public and private institutions in four fields: (a) the provision of credit, (b) the training of workers and entrepreneurs, (c) the provision of real services, and (d) wage negotiations. The paper suggests that institutions played more of a role in later than earlier phases of growth. It points toward a new model of industrial policy based on local institutions but emphasizes that there is as yet little systematic assessment of the role of such institutions.
TL;DR: Six experiments explored why the identification of the two members of a pair of diotic, simultaneous, steady-state vowels improves with a difference in fundamental frequency (delta F0), and showed that at small delta F0's only the first-formant region contributes to improvements in identification accuracy, whereas with larger delta F 0's the higher formant region may also contribute.
Abstract: Six experiments explored why the identification of the two members of a pair of diotic, simultaneous, steady‐state vowels improves with a difference in fundamental frequency (ΔF0). Experiment 1 confirmed earlier reports that a ΔF0 improves identification of 200‐ms but not 50‐ms duration ‘‘double vowels’’; identification improves up to 1 semitone ΔF0 and then asymptotes. In such stimuli, all the formants of a given vowel are excited by the same F0, providing listeners with a potential grouping cue. Subsequent experiments asked whether the improvement in identification with ΔF0 for the longer vowels was due to listeners using the consistent F0 within each vowel of a pair to group formants appropriately. Individual vowels were synthesized with a different F0 in the region of the first formant peak from in the region of the higher formant peaks. Such vowels were then paired so that the first formant of one vowel bore the same F0 as the higher formants of the other vowel. These across‐formant inconsistencies i...
TL;DR: This paper argues that this formulation fails to capture the dynamic character of the model and proposes an alternative formulation, which appears to be more consistent with Grossman's theoretical model and which may also explain the apparent rejections of themodel by the data in the author's earlier empirical work.
Abstract: Previous tests of Grossman's model of the demand for health have been based on Grossman's own empirical formulation. This paper argues that this formulation fails to capture the dynamic character of the model. It proposes an alternative formulation, which appears to be more consistent with Grossman's theoretical model and which may also explain the apparent rejections of the model by the data in the author's earlier empirical work. The paper also presents some empirical results obtained using the new formulation, which are, on the whole, consistent with the predictions of Grossman's theoretical model.
TL;DR: In this article, the formation of C60 and C70 by pyrolysis of naphthalene at ∼1,000 °C was reported, showing that closed fullerene cages can be built from well defined aromatic fragments.
Abstract: THE formation of bulk quantities of C60 by arc discharge between carbon electrodes in an atmosphere of helium1 or argon2,3 has led to an explosion in fullerene research. Methods for improving the rate of fullerene production have included increasing the reactor size and the diameter of the carbon rods, and varying the rate of rod consumption and helium pressure4. Systems using several rods have also been employed5,6. The ideal method, however, would involve a continuous process that does not require rod replacement. Approaches using carbon granules6 and powders7 have been reported, as well as combustion methods using hydrocarbons8,9. Here we report the formation of C60 and C70 by pyrolysis of naphthalene at ∼1,000 °C. C60 and C70 are formed by the 'patching together' of six and seven naphthalene molecules respectively, as demonstrated by mass-spectrometric analysis of intermediate products. These results point to a continuous method of fullerene formation, and also show that closed fullerene cages can be built from well defined aromatic fragments.
TL;DR: This work investigates models of `intermediate' inflation, where the scale factor $a(t)$ grows as a(t)=\mathrm{exp}(A{t}^{f})$, and finds that the perturbation spectral index $n$ can be greater than unity on astrophysical scales.
Abstract: We investigate models of `intermediate' inflation, where the scale factor $a(t)$ grows as $a(t)=\mathrm{exp}(A{t}^{f})$, $0lfl1$, $A$ constant. These solutions arise as exact analytic solutions for a given class of potentials for the inflaton $\ensuremath{\varphi}$. For a simpler class of potentials falling off as a power of $\ensuremath{\varphi}$ they arise as slow-roll solutions, and in particular they include, for $f=\frac{2}{3}$, the class of potentials which give the Harrison-Zel'dovich spectrum. The perturbation spectral index $n$ can be greater than unity on astrophysical scales. It is also possible to generate substantial gravitational waves while keeping the scalar spectrum close to scale invariance; this latter possibility performs well when confronted with most observational data.
TL;DR: In this paper, the authors proposed that the Werner syndrome gene is a "counting" gene controlling the number of times that human cells are able to divide before terminal differentiation, and showed that the cells in these cultures usually exit, apparently irreversibly, from the cell cycle at a faster rate than do normal cells.
Abstract: Werner syndrome is a rare, autosomal, recessive condition that is frequently studied as a model of some aspects of human aging, although the behavioral changes that are usually associated with old age are only seen very infrequently. A most striking aspect of the phenotype of Werner syndrome, presumably arising from the same gene defect, is a dramatic shortening of the replicative life-span of dermal fibroblasts in vitro. The finite replicative life-span of human cells in vitro is due to the stochastic loss of replicative ability in a continuously increasing fraction of newborn cells at every generation. Normal human fibroblasts achieve approximately 60 population doublings in culture, while Werner syndrome cells usually only achieve approximately 20 population doublings. We describe an analysis of the replicative ability of fibroblasts from Werner syndrome patients and demonstrate that the cells in these cultures usually exit, apparently irreversibly, from the cell cycle at a faster rate than do normal cells, although they mostly start off with a good replicative ability. We propose that the Werner syndrome gene is a "counting" gene controlling the number of times that human cells are able to divide before terminal differentiation.
TL;DR: In this paper, the authors compare defecation patterns at boundary and hinterland latrines, in order to test the hypothesis that these two types of latrine have a similar function.
Abstract: Badgers (Meles meles) defecate, urinate and scent mark at latrines which seem to have a territorial function. The main aim of the present study was to compare defecation patterns at boundary and hinterland latrines, in order to test the hypothesis that these two types of latrine have a similar function. We investigated latrine use by means of a year-round survey of all the latrines in 7 badger territories, by bait-marking of 15 territories, and by monitoring latrine use in 6 radio-collared badgers belonging to three social groups. The spatial distribution of latrines within a territory was bimodal, with the greatest densities oflatrines close to the outside, and close to the centre, of the territory respectively. Boundary latrines were larger and more consistently used than hinterland latrines, but these differences could be accounted for by the fact that boundary latrines are visited by the members of more than one social group. Defecation at latrines was subject to seasonal variation, with a major peak in latrine use in spring and a minor peak in autumn. The spring peak was largely attributable to an increase in the use of hinterland latrines, the autumn peak to an increase in the use of boundary latrines. Males visited boundary latrines considerably more often than did females, but both sexes visited hinterland latrines equally often. Overmarking occurred equally often at both types of latrine and involved animals from the same as well as from different groups, but there was a significant tendency for more between-group than within-group overmarking. Overmarking occurred mainly on fresh, as opposed to old, faeces deposits. The sex and seasonal differences in use of boundary latrines suggest that these function at least partly as a form of mate-guarding, to deter neighbouring males from entering a territory for mating purposes. It is less clear why females mark at hinterland latrines. One possibility, consistent with the observed spatial distribution of hinterland latrines, is that they function to defend the main burrow system, which is used for breeding; another is that they carry information about social status. Overmarking probably serves to obliterate the marks of competitors, which are members of neighbouring social groups in the case of boundary latrines, but may be members of the same social group in the case of hinterland latrines. We conclude that previous ideas about the function of territoriality in badgers, and about the information conveyed by latrines, are oversimplified.
TL;DR: The negative symbiosis between the mining and other tradable sectors which mutes both the rate and efficiency of economic growth can subvert both sustainability goals as mentioned in this paper, and sustainable development requires that consumption by present generations should not be at the expense of future generations.
TL;DR: Intracellular levels of nitric oxide generated by interleukin‐1β‐induced nitricoxide synthase were sufficient to cause DNA damage in islet cells and HIT‐T15 cells, suggesting thatNitric oxide itself, rather than Superoxide or peroxynitrite may be the active species.
TL;DR: This paper shows how the testing equivalences and preorders on transition systems may be interpreted as instances of generalized bisimulation equivalence and prebisimulation preorders and uses algorithms for determining the (pre)bisimulations relations in the case of finite-state transition systems.
Abstract: In this paper we show how the testing equivalences and preorders on transition systems may be interpreted as instances of generalized bisimulation equivalences and prebisimulation preorders. The characterization relies on defining transformations on the transition systems in such a way that the testing relations on the original systems correspond to (pre)bisimulation relations on the altered systems. On the basis of these results, it is possible to use algorithms for determining the (pre)bisimulation relations in the case of finite-state transition systems to compute the testing relations.
TL;DR: It is demonstrated here that both NO synthase and NO-activated guanylyl cyclase are present in the brain of the locust Schistocerca gregaria, indicating, for the first time, that the NO-cyclic GMP signalling pathway exists in invertebrate nervous systems.
TL;DR: A full reconstruction of the functional form of the potential will not be possible within the foreseeable future, but with a knowledge of the dark matter components, it should soon be possible to combine intermediate-scale data with measurements of large-scale cosmic microwave background anisotropies to yield useful information regarding the potential.
Abstract: Generalizing the original work by Hodges and Blumenthal, we outline a formalism which allows one, in principle, to reconstruct the potential of the inflaton field from knowledge of the tensor gravitational wave spectrum or the scalar density fluctuation spectrum, with special emphasis on the importance of the tensor spectrum. We provide some illustrative examples of such reconstruction. We then discuss in some detail the question of whether one can use real observations to carry out this procedure. We conclude that, practice, a full reconstruction of the functional form of the potential will not be possible within the foreseeable future. However, with a knowledge of the dark matter components, it should soon be possible to combine intermediate-scale data with measurements of large-scale cosmic microwave background anisotropies to yield useful information regarding the potential.