Showing papers by "University of Warwick published in 1998"

AtPIN2 defines a locus of Arabidopsis for root gravitropism control

Abstract: The molecular mechanisms underlying gravity perception and signal transduction which control asymmetric plant growth responses are as yet unknown, but are likely to depend on the directional flux of the plant hormone auxin. We have isolated an Arabidopsis mutant of the AtPIN2 gene using transposon mutagenesis. Roots of the Atpin2::En701 null-mutant were agravitropic and showed altered auxin sensitivity, a phenotype characteristic of the agravitropic wav6-52 mutant. The AtPIN2 gene was mapped to chromosome 5 (115.3 cM) corresponding to the WAV6 locus and subsequent genetic analysis indicated that wav6-52 and Atpin2::En701 were allelic. The AtPIN2 gene consists of nine exons defining an open reading frame of 1944 bp which encodes a 69 kDa protein with 10 putative transmembrane domains interrupted by a central hydrophilic loop. The topology of AtPIN2p was found to be similar to members of the major facilitator superfamily of transport proteins. We have shown that the AtPIN2 gene was expressed in root tips. The AtPIN2 protein was localized in membranes of root cortical and epidermal cells in the meristematic and elongation zones revealing a polar localization. These results suggest that AtPIN2 plays an important role in control of gravitropism regulating the redistribution of auxin from the stele towards the elongation zone of roots.

Board Control, Remuneration Committees, and Top Management Compensation

Abstract: Assesses the relationship between boards of directors, compensation committees and top management pay, focusing on the role and impact of corporate governance mechanisms and the structure of boards of directors to explain variations in top management pay in the UK. Uses data from the 'Financial Times' top 100 companies to examine the relationship between: top management compensation, non-executive directors and corporate performance; top management compensation, existence of compensation committees and proportion of non-executives on these committees; and the relationship between top management compensation and Chief Executive Officer (CEO) duality. Finds that, in general, boardroom control and vigilance has a limited effect in shaping top management compensation, neither the proportion of outside directors, nor CEO duality being related to management compensation; and companies adopting compensation committees have higher levels of top management pay. Demonstrates that the direct effect of boardroom control variables on the level of management compensation is minimal.

Family firm research: the need for a methodological rethink

Abstract: The scale of family company activity in the United Kingdom was measured with regard to several family firm definitions. This study confirms that family companies are a numerically important group o...

Forecasting Economic Time Series

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

’I Heard It on the Grapevine’: ‘hot’ knowledge and school choice

Abstract: This paper is one of a number of related pieces which address the issue of parental choice through a careful Straussian analysis of interview data. The focus here is upon the structures and processes underlying the use of grapevine’ knowledge, which parents elicit and disseminate in choosing a school. It is argued that this immediate or ‘hot’ knowledge is of particular importance to many parents and is set over and against the ‘cold’ formal knowledge produced by schools themsebes or published as examination results or league tables. Grapevine knowledge is socially embedded in networks and localities and is distributed unevenly across and used differently by different social‐class groups. The paper concludes by suggesting that the stress and anxiety involved in choice for many parents is a product of unstable cultural values, and the slippery signs systems now surrounding ‘school’ at a time of increased economic uncertainty.

Entrepreneurial learning and the growth process in SMEs

Abstract: This paper draws on case and interview material, from research with entrepreneurs in small and medium‐sized enterprises (SMEs) to examine the process of entrepreneurship and entrepreneurial learning in SMEs. The cases have been drawn from different sectors including services, manufacturing and technology‐based sectors such as hydraulics, and software development. This paper reviews the contribution of organisational learning theories, which, it is argued, have been developed for large firms rather than SMEs. More appropriate theories are examined from fields that accepted the impact of uncertainty and dynamics in decision making, such as Schumpeterian dynamic approaches to learning and development. Case study evidence is presented on the nature of entrepreneurial learning in growth SMEs and compared with theories in the literature.

Overlapping functions of components of a bacterial Sec-independent protein export pathway.

Abstract: We describe the identification of two Escherichia coli genes required for the export of cofactor-containing periplasmic proteins, synthesized with signal peptides containing a twin arginine motif. Both gene products are homologous to the maize HCF106 protein required for the translocation of a subset of lumenal proteins across the thylakoid membrane. Disruption of either gene affects the export of a range of such proteins, and a complete block is observed when both genes are inactivated. The Sec protein export pathway was unaffected, indicating the involvement of the gene products in a novel export system. The accumulation of active cofactor-containing proteins in the cytoplasm of the mutant strains suggests a role for the gene products in the translocation of folded proteins. One of the two HCF106 homologues is encoded by the first gene of a four cistron operon, tatABCD, and the second by an unlinked gene, tatE. A mutation previously assigned to the hcf106 homologue encoded at the tatABCD locus, mttA, lies instead in the tatB gene.

Aligning male and female linkage maps of apple (Malus pumila Mill.) using multi-allelic markers

Abstract: Linkage maps for the apple cultivars ‘Prima’ and ‘Fiesta’ were constructed using RFLP, RAPD, isozyme, AFLP, SCAR and microsatellite markers in a ‘Prima’בFiesta’ progeny of 152 individuals. Seventeen linkage groups, putatively corresponding to the seventeen haploid apple chromosomes, were obtained for each parent. These maps were aligned using 67 multi-allelic markers that were heterozygous in both parents. A large number of duplicate RFLP loci was observed and, in several instances, linked RFLP markers in one linkage group showed corresponding linkage in another linkage group. Distorted segregation was observed mainly in two regions of the genome, especially in the male parent alleles. Map positions were provided for resistance genes to scab and rosy leaf curling aphid (Vf and Sd 1, respectively) for the fruit acidity gene Ma and for the self-incompatibility locus S. The high marker density and large number of mapped codominant RFLPs and some microsatellite markers make this map an ideal reference map for use in other progenies also and a valuable tool for the mapping of quantitative trait loci.

The Functional Analysis of English : A Hallidayan Approach

Abstract: Preliminaries - Grammar and Meaning Labels Subject and Related Functions Information Structure and Thematic Structure Text and Texture Process and Participant The Nominal Group Rankshifted Clauses Clause Complexes: Expansion Clause Complexes: Projection Applications of Functional Analysis Historical Perspectives.

Training and Labour Market Flexibility: Is There a Trade‐off?

Abstract: This paper explores the nexus between work-related training and labour market ‘flexibility’ (which we proxy by contract type, part-time employment and lack of union coverage), using the first five waves of the British Household Panel Survey (BHPS) conducted over the period 1991–5. Our results show that workers on short-term employment contracts, who are working part-time or are not covered by a union collective agreement, are significantly less likely to be involved in any work-related training to improve or increase their skills. These findings suggest that there is a trade-off between expanding the more marginal forms of employment and expanding the proportion of the work-force getting work-related training.

The taxation of discrete investment choices

Abstract: Traditional analysis of the taxation of income from capital has focused on the impact of tax on marginal investment decisions; the principal impact of tax on investment is through the cost of capital, and is generally measured by an effective marginal tax rate. In this paper, we consider cases in which investors face a choice between two or more mutually exclusive projects, both of which are expected to earn at least the minimum required rate of return. Examples include the location decisions of multinationals, firms' choice of technology, and the choice of investment projects in the presence of binding financial constraints. In these cases the choice depends on the effective average tax rate. We propose a measure of this rate and demonstrate its relationship to the conventional effective marginal tax rate. Estimates of both are presented and compared for domestic and international investment in Germany, Japan, the UK and USA between 1979 and 1997.

A Review of Machine Scheduling: Complexity, Algorithms and Approximability

Abstract: The scheduling of computer and manufacturing systems has been the subject of extensive research for over forty years. In addition to computers and manufacturing, scheduling theory can be applied to many areas including agriculture, hospitals and transport. The main focus is on the efficient allocation of one or more resources to activities over time. Adopting manufacturing terminology, a job consists of one or more activities, and a machine is a resource that can perform at most one activity at a time. We concentrate on deterministic machine scheduling for which it is assumed that all data that define a problem instance are known with certainty.

A Socio‐Technical View of Knowledge Sharing at Buckman Laboratories

Abstract: This empirical study reports a unique implementation process of knowledge sharing from Buckman Laboratories. Through a socio‐technical perspective on Knowledge Management, this paper highlights the interplay between Knowledge Management systems and the organizational context.

Modelling and simulation of a supply chain in an uncertain environment

Abstract: This paper describes fuzzy modelling and simulation of a supply chain (SC) in an uncertain environment, as the first step in developing a decision support system. An SC is viewed as a series of facilities that performs the procurement of raw material, its transformation to intermediate and end-products, and distribution and selling of the end-products to customers. All the facilities in the SC are coupled and interrelated in a way that decisions made at one facility affect the performance of others. SC fuzzy models and a simulator cover operational SC control. The objective is to determine the stock levels and order quantities for each inventory in an SC during a finite time horizon to obtain an acceptable delivery performance at a reasonable total cost for the whole SC. Two sources of uncertainty inherent in the external environment in which the SC operates were identified and modelled: customer demand and external supply of raw material. They were interpreted and represented by fuzzy sets. In addition to the fuzzy SC models, a special SC simulator was developed. The SC simulator provides a dynamic view of the SC and assesses the impact of decisions recommended by the SC fuzzy models on SC performance.

Rapid Diversification of Marine Picophytoplankton with Dissimilar Light-Harvesting Structures Inferred from Sequences of Prochlorococcus and Synechococcus (Cyanobacteria)

Abstract: Cultured isolates of the unicellular planktonic cyanobacteria Prochlorococcus and marine Synechococcus belong to a single marine picophytoplankton clade. Within this clade, two deeply branching lineages of Prochlorococcus, two lineages of marine A Synechococcus and one lineage of marine B Synechococcus exhibit closely spaced divergence points with low bootstrap support. This pattern is consistent with a near-simultaneous diversification of marine lineages with divinyl chlorophyll b and phycobilisomes as photosynthetic antennae. Inferences from 16S ribosomal RNA sequences including data for 18 marine picophytoplankton clade members were congruent with results of psbB and petB and D sequence analyses focusing on five strains of Prochlorococcus and one strain of marine A Synechococcus. Third codon position and intergenic region nucleotide frequencies vary widely among members of the marine picophytoplankton group, suggesting that substitution biases differ among the lineages. Nonetheless, standard phylogenetic methods and newer algorithms insensitive to such biases did not recover different branching patterns within the group, and failed to cluster Prochlorococcus with chloroplasts or other chlorophyll b-containing prokaryotes. Prochlorococcus isolated from surface waters of stratified, oligotrophic ocean provinces predominate in a lineage exhibiting low G + C nucleotide frequencies at highly variable positions.

Assessing the Impact of Secondary Structure and Solvent Accessibility on Protein Evolution

Abstract: Empirically derived models of amino acid replacement are employed to study the association between various physical features of proteins and evolution The strengths of these associations are statistically evaluated by applying the models of protein evolution to 11 diverse sets of protein sequences Parametric bootstrap tests indicate that the solvent accessibility status of a site has a particularly strong association with the process of amino acid replacement that it experiences Significant association between secondary structure environment and the amino acid replacement process is also observed Careful description of the length distribution of secondary structure elements and of the organization of secondary structure and solvent accessibility along a protein did not always significantly improve the fit of the evolutionary models to the data sets that were analyzed As indicated by the strength of the association of both solvent accessibility and secondary structure with amino acid replacement, the process of protein evolution-both above and below the species level-will not be well understood until the physical constraints that affect protein evolution are identified and characterized

How Did the United States and Germany Overtake Britian? A Sectoral Analysis of Comparative Productivity Levels, 1870–1990

Abstract: A sectoral analysis of comparative labor productivity levels over the period 1870 to 1990 suggests mechanisms of catching-up and forging ahead that are rather different from those found in the conventional literature. Both Germany and the United States caught up with and overtook Britain in terms of aggregate labor productivity largely by shifting resources out of agriculture and improving their relative productivity position in services rather than by improving their position in manufacturing. Although capital played some role, the changes in comparative labor productivity also reflected changes in comparative total factor productivity, related to technology and organization.

SME Flexibility and the Role of Information Systems

Abstract: Small and medium-size enterprises (SMEs) are a major component of all economies and are generally considered to be flexible, adaptive organisations. Although lagging behind their larger counterparts, SMEs are beginning to invest in information systems. Using data derived from a set of manufacturing SMEs located in the U.K., this paper investigates whether SMEs really do exhibit flexibility and if their use of information technology enhances or inhibits such flexibility.

Virus taxonomy - San Diego 1998.

Abstract: The 27th Meeting of the Executive Committee of the International Committee on Taxonomy of Viruses (ICTV) was held at the Scripps Research Institute, San Diego, California, on 7th and 8th March of this year. The principle business was review of new taxonomic proposals submitted by the individual Study Groups of the ICTV. The taxonomic proposals listed below are those that were approved by the Executive Committee of the ICTV. These new proposals, subject to formal ratification by postal ballot of the national membership of the ICTV, will be included in the up-dated Universal Taxonomy of Viruses, which will be published as the 7th Report of the ICTV. The Executive Committee plans to have the 7th Report available for sale at the 11th International Congress of Virology, which will take place in Sydney, Australia, in August 1999. The Executive Committee aims to replace vernacular names by international names throughout the Universal Taxonomy, but in certain taxa the designation “...-like viruses” remains. In some cases this is indicative of rejection by the Executive Committee of an international name proposed by a Study Group, or vice versa. In other cases it represents continuing indecision about the definitive criteria for designation of species. A major change in practice was approved at the San Diego Meeting, which is illustrated in the list of new taxonomic proposals that follows. In future the names of all virus species will be italicised and the initial letter will be capitalised. The names of viruses having the status of tentative species only will not be given in italics, but will have the initial letter capitalised. Transition to italicisation will signal recognition of full species status. The Executive Committee of the ICTV has approved the following new taxonomic proposals: Proposals that were rejected or referred back are not included in the list.

Unemployment Equilibria and Input Prices: Theory and Evidence from the United States

Abstract: The paper develops an efficiency-wage model where input prices affect the equlibrium rate of unemployment. We show that a simple framework based on only two prices (the real price of oil and the real rate of interest) is able to explain the main post-war movements in the rate of U.S. joblessnss. The equations do well in forecasting unemployment many out-of-sample, and provide evidence that the oil price spike associated with Iraq's invasion of Kuweit appears to be a component of the "mystery" recession which followed.