6,031 research outputs found

    An Audit of export services in England: developing business focused support

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    One of the key thresholds in the development of small and medium sized enterprises is exporting and trading internationally. A brief review of the academic and practitioner literature highlights a number of benefits associated with exporting that include exposure to differing ways of ‘how to do’ business and opportunities for the development of joint ventures and strategic alliances. However, several regions within the United Kingdom perceive that they have too few SMEs who trade internationally. Recent estimates suggest that approximately three per cent of the SMEs in the United Kingdom are actively exporting (Bank of England, 1999). Government policy makers have responded to such concerns by providing a range of support programmes to increase the number of SMEs who trade internationally and enhance the skills and capabilities of those SMEs who export, so that they can efficiently and effectively manage the exporting and market development process. Therefore, in the majority of the English regions, there are a range of publicly funded organisations providing advice, consultancy, information and training to SMEs wishing to trade internationally and those businesses already exporting. In addition, SMEs can access a number of export services from private sector organisations such as banks, accountants, freight forwarders and export agents. There has been no overall national ‘stocktake’ or audit of such provision. However, the need for such a stocktake is becoming increasingly important due to the introduction of a number of new support organisations into the institutional landscape and the re-organisation and re-branding of British Trade International as Trade Partners UK and the appointment of a series of Regional International Trade Directors. The introduction of the Small Business Service will have a major impact on the coverage and nature of provision for exporting SMEs within each of the English regions. The introduction of the Small Business Service, however, provides an opportunity to explore and examine alternative configurations of small business support and the types of organisation that are best placed to satisfy the needs of exporting SMEs. This paper presents the key findings to emerge from an audit of export services within each of the English regions. Based on a research and development project undertaken in conjunction with Trade Partners UK, the paper offers insights into: • The coverage of export services available to SMEs within England; • The effectiveness and appropriateness of current configuration of export services; • The ways in which the effectiveness of the current configuration of export services could be enhanced. The audit was based on a series of face-to-face and telephone interviews with local, regional and national providers of export provision. A key argument within the paper is that effective configurations of export and trade development support arise from insights into, and appropriate responses to, the exporting and trade development process as experienced by SMEs. The paper concludes with a number of implications in terms of how business-driven forms of support can be developed.</p

    Energy flow of moving dissipative topological solitons

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    We study the energy flow due to the motion of topological solitons in nonlinear extended systems in the presence of damping and driving. The total field momentum contribution to the energy flux, which reduces the soliton motion to that of a point particle, is insufficient. We identify an additional exchange energy flux channel mediated by the spatial and temporal inhomogeneity of the system state. In the well-known case of a DC external force the corresponding exchange current is shown to be small but non-zero. For the case of AC driving forces, which lead to a soliton ratchet, the exchange energy flux mediates the complete energy flow of the system. We also consider the case of combination of AC and DC external forces, as well as spatial discretization effects.Comment: 24 pages, 5 figures, submitted to Chao

    Programmable DNA looping using engineered bivalent dCas9 complexes

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    DNA looping is a ubiquitous and critical feature of gene regulation. Although DNA looping can be efficiently detected, tools to readily manipulate DNA looping are limited. Here we develop CRISPR-based DNA looping reagents for creation of programmable DNA loops. Cleavage-defective Cas9 proteins of different specificity are linked by heterodimerization or translational fusion to create bivalent complexes able to link two separate DNA regions. After model-directed optimization, the reagents are validated using a quantitative DNA looping assay in E. coli. Looping efficiency is ~15% for a 4.7 kb loop, but is significantly improved by loop multiplexing with additional guides. Bivalent dCas9 complexes are also used to activate endogenous norVW genes by rewiring chromosomal DNA to bring distal enhancer elements to the gene promoters. Such reagents should allow manipulation of DNA looping in a variety of cell types, aiding understanding of endogenous loops and enabling creation of new regulatory connections.Nan Hao, Keith E. Shearwin, Ian B. Dod

    Recoverin Regulates Light-dependent Phosphodiesterase Activity in Retinal Rods

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    The Ca2+-binding protein recoverin may regulate visual transduction in retinal rods and cones, but its functional role and mechanism of action remain controversial. We compared the photoresponses of rods from control mice and from mice in which the recoverin gene was knocked out. Our analysis indicates that Ca2+-recoverin prolongs the dark-adapted flash response and increases the rod's sensitivity to dim steady light. Knockout rods had faster Ca2+ dynamics, indicating that recoverin is a significant Ca2+ buffer in the outer segment, but incorporation of exogenous buffer did not restore wild-type behavior. We infer that Ca2+-recoverin potentiates light-triggered phosphodiesterase activity, probably by effectively prolonging the catalytic activity of photoexcited rhodopsin

    Energy Flow Puzzle of Soliton Ratchets

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    We study the mechanism of directed energy transport for soliton ratchets. The energy flow appears due to the progressive motion of a soliton (kink) which is an energy carrier. However, the energy current formed by internal system deformations (the total field momentum) is zero. We solve the underlying puzzle by showing that the energy flow is realized via an {\it inhomogeneous} energy exchange between the system and the external ac driving. Internal kink modes are unambiguously shown to be crucial for that transport process to take place. We also discuss effects of spatial discretization and combination of ac and dc external drivings.Comment: 4 pages, 3 figures, submitted to PR

    Efficient chromosomal-scale DNA looping in Escherichia coli using multiple DNA-looping elements

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    Genes are frequently regulated by interactions between proteins that bind to the DNA near the gene and proteins that bind to DNA sites located far away, with the intervening DNA looped out. But it is not understood how efficient looping can occur when the sites are very far apart. We develop a simple theoretical framework that relates looping efficiency to the energetic cost and benefit of looping, allowing prediction of the efficiency of single or multiple nested loops at different distances. Measurements of absolute loop efficiencies for Lac repressor and Îť CI using gene expression reporters in Escherichia coli cells show that, as predicted by the model, long-range DNA looping between a pair of sites can be strongly enhanced by the use of nested DNA loops or by the use of additional protein-binding sequences. A combination of these approaches was able to generate efficient DNA looping at a 200 kb distance.Nan Hao, Kim Sneppen, Keith E. Shearwin, Ian B. Dod

    Power management optimisation for hybrid electric systems using reinforcement learning and adaptive dynamic programming

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    This paper presents an online learning scheme based on reinforcement learning and adaptive dynamic programming for the power management of hybrid electric systems. Current methods for power management are conservative and unable to fully account for variations in the system due to changes in the health and operational conditions. These conservative schemes result in less efficient use of available power sources, increasing the overall system costs and heightening the risk of failure due to the variations. The proposed scheme is able to compensate for modelling uncertainties and the gradual system variations by adapting its performance function using the observed system measurements as reinforcement signals. The reinforcement signals are nonlinear and consequently neural networks are employed in the implementation of the scheme. Simulation results for the power management of an autonomous hybrid system show improved system performance using the proposed scheme as compared with a conventional offline dynamic programming approach

    Vortex stability in nearly two-dimensional Bose-Einstein condensates with attraction

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    We perform accurate investigation of stability of localized vortices in an effectively two-dimensional ("pancake-shaped") trapped BEC with negative scattering length. The analysis combines computation of the stability eigenvalues and direct simulations. The states with vorticity S=1 are stable in a third of their existence region, 0<N<(1/3)Nmax⁡(S=1)0<N<(1/3)N_{\max}^{(S=1)}, where NN is the number of atoms, and Nmax⁡(S=1)N_{\max}^{(S=1)} is the corresponding collapse threshold. Stable vortices easily self-trap from arbitrary initial configurations with embedded vorticity. In an adjacent interval, (1/3)Nmax⁡(S=1)<N<(1/3)N_{\max }^{(S=1)}<N< 0.43Nmax⁡(S=1)\allowbreak 0.43N_{\max}^{(S=1)}, the unstable vortex periodically splits in two fragments and recombines. At N>N> 0.43Nmax⁡(S=1)\allowbreak 0.43N_{\max}^{(S=1)}, the fragments do not recombine, as each one collapses by itself. The results are compared with those in the full 3D Gross-Pitaevskii equation. In a moderately anisotropic 3D configuration, with the aspect ratio 10\sqrt{10}, the stability interval of the S=1 vortices occupies ≈40\approx 40% of their existence region, hence the 2D limit provides for a reasonable approximation in this case. For the isotropic 3D configuration, the stability interval expands to 65% of the existence domain. Overall, the vorticity heightens the actual collapse threshold by a factor of up to 2. All vortices with S≥2S\geq 2 are unstable.Comment: 21 pages, 8 figures, to appear in Physical Review

    The Effects of Tree Density on Pasture Production Under Acacia Melanoxylon

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    Silvi-pastoral systems could contribute to greater total productivity and more sustainable land management of grazed pastures in New Zealand. Despite this potential, little is known of the interactions of tree species and environment on pasture growth. In this paper we report the effects of tree density on pasture yield in an Acacia melanoxylon silvi-pastoral system. The results show decreasing pasture yield with increasing tree density, although the extent of the reduction is less than would be expected under Pinus radiata. Results suggest that shade is the dominant factor causing yield decline in this study, while reduced N availability is clearly implicated in previous studies with pine trees. This study will provide more data on which a mechanistic model of tree-pasture interactions can be based
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