5,843 research outputs found

    Yield performance of cassava genotypes in the forest and coastal ecologies of Southern Ghana

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    Root yield performances of 10 cassava genotypes were assessed across six environments to determine stable cassava (Manihot esculenta) cultivar(s) for root yield in southern Ghana. The assessments were carried out in the forest zone (Fumesua), coastal savanna zone (Ohawu) and coastal savanna zone (Pokuase) in the 2007-2008 and 2008-2009 growing seasons. The experimental layout was a randomized complete block design with three replications. Additive main effects and multiplicative interactions analysis (AMMI) indicated that genotype by environment interactions were significant. Genotype 6 (CR52A-25) was the highest yielding genotype with a root yield of 60.33 kg ha-1, while Genotype 9 (CR59-4) had the lowest root yield of 26.86 kg ha-1. Root yield was significantly lower (P = 0.001) at the forest zone compared to the coastal savanna zones

    A selected ion flow tube study of the ion-molecule reactions of monochloroethene, trichloroethene and tetrachloroethene

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    Data for the rate coefficients and product cations of the reactions of a large number of atomic and small molecular cations with monochloroethene, trichloroethene and tetrachloroethene in a selected ion flow tube at 298 K are reported. The recombination energy of the ions range from 6.27 eV (H3_3O+^+) through to 21.56 eV (Ne+^+). Collisional rate coefficients are calculated by modified average dipole orientation theory and compared with experimental values. Thermochemistry and mass balance predict the most feasible neutral products. Together with previously reported results for the three isomers of dichloroethene (J. Phys. Chem. A., 2006, 110, 5760), the fragment ion branching ratios have been compared with those from threshold photoelectron photoion coincidence spectroscopy over the photon energy range 9-22 eV to determine the importance or otherwise of long-range charge transfer. For ions with recombination energy in excess of the ionisation energy of the chloroethene, charge transfer is energetically allowed. The similarity of the branching ratios from the two experiments suggest that long-range charge transfer is dominant. For ions with recombination energy less than the ionisation energy, charge transfer is not allowed; chemical reaction can only occur following formation of an ion-molecule complex, where steric effects are more significant. The products that are now formed and their percentage yield is a complex interplay between the number and position of the chlorine atoms with respect to the C=C bond, where inductive and conjugation effects can be important

    Disease mapping of early- and late-stage cancer to monitor inequalities in early detection: a study of cutaneous malignant melanoma

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    We consider disease mapping of early- and late-stage cancer, in order to identify and monitor inequalities in early detection. Our method is demonstrated by mapping cancer incidence at high geographical resolution using data on 10,302 cutaneous malignant melanoma (CMM) cases within the 3.7 million population of South-West Sweden. The cases were geocoded into small-areas, each with a population size between 600 and 2600 and accessible socio-demographic data. Using the disease mapping application Rapid Inquiry Facility (RIF) 4.0, we produced regional maps to visualise spatial variations in stage I, II and III–IV CMM incidences, complemented by local maps to explore the variations within two urban areas. Pronounced spatial disparities in stage I CMM incidence were revealed by the regional and local maps. Stage I CMM incidence was markedly higher in wealthier small-areas, in particular within each urban area. A twofold higher stage I incidence was observed, on average, in the wealthiest small-areas (upper quintile) than in the poorest small-areas (lower quintile). We identified in the regional map of stage III–IV CMM two clusters of higher or lower than expected late-stage incidences which were quite distinct from those identified for stage I. In conclusion, our analysis of CMM incidences supported the use of this method of cancer stage incidence mapping for revealing geographical and socio-demographic disparities in cancer detection

    Focused Local Search for Random 3-Satisfiability

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    A local search algorithm solving an NP-complete optimisation problem can be viewed as a stochastic process moving in an 'energy landscape' towards eventually finding an optimal solution. For the random 3-satisfiability problem, the heuristic of focusing the local moves on the presently unsatisfiedclauses is known to be very effective: the time to solution has been observed to grow only linearly in the number of variables, for a given clauses-to-variables ratio α\alpha sufficiently far below the critical satisfiability threshold αc4.27\alpha_c \approx 4.27. We present numerical results on the behaviour of three focused local search algorithms for this problem, considering in particular the characteristics of a focused variant of the simple Metropolis dynamics. We estimate the optimal value for the ``temperature'' parameter η\eta for this algorithm, such that its linear-time regime extends as close to αc\alpha_c as possible. Similar parameter optimisation is performed also for the well-known WalkSAT algorithm and for the less studied, but very well performing Focused Record-to-Record Travel method. We observe that with an appropriate choice of parameters, the linear time regime for each of these algorithms seems to extend well into ratios α>4.2\alpha > 4.2 -- much further than has so far been generally assumed. We discuss the statistics of solution times for the algorithms, relate their performance to the process of ``whitening'', and present some conjectures on the shape of their computational phase diagrams.Comment: 20 pages, lots of figure

    In situ hybridisation and S1 mapping show that the presence of infiltrating plasma cells is associated with poor prognosis in breast cancer.

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    In order to identify potential markers of prognosis in breast cancer, representative cDNA libraries were constructed using RNA isolated from primary breast tumour tissue associated with good and poor prognosis. Cross-screening of these libraries repeatedly identified cloned mRNA species associated with the immune system, in particular B-cells, in libraries derived from tumours of poor prognosis. We have used one of these a kappa IV light chain cDNA probe, in two complementary studies to investigate the relationship between immunoglobin gene expression and prognosis. The results obtained using a combination of S1 mapping, RNA blotting and in situ hybridisation demonstrate that the presence of plasma cells, as defined by infiltrating cells which express high levels of immunoglobulin kappa-chain mRNA, is associated with a poor prognosis

    Minimizing energy below the glass thresholds

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    Focusing on the optimization version of the random K-satisfiability problem, the MAX-K-SAT problem, we study the performance of the finite energy version of the Survey Propagation (SP) algorithm. We show that a simple (linear time) backtrack decimation strategy is sufficient to reach configurations well below the lower bound for the dynamic threshold energy and very close to the analytic prediction for the optimal ground states. A comparative numerical study on one of the most efficient local search procedures is also given.Comment: 12 pages, submitted to Phys. Rev. E, accepted for publicatio

    Investigation of shock waves in explosive blasts using fibre optic pressure sensors

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    The published version of this article may be accessed at the link below. Copyright @ IOP Publishing, 2006.We describe miniature all-optical pressure sensors, fabricated by wafer etching techniques, less than 1 mm(2) in overall cross-section with rise times in the mu s regime and pressure ranges typically 900 kPa (9 bar). Their performance is suitable for experimental studies of the pressure-time history for test models exposed to shocks initiated by an explosive charge. The small size and fast response of the sensors promises higher quality data than has been previously available from conventional electrical sensors, with potential improvements to numerical models of blast effects. Results from blast tests are presented in which up to six sensors were multiplexed, embedded within test models in a range of orientations relative to the shock front.Support from the UK Engineering&Physical Sciences Research Council and Dstl Fort Halstead through the MoD Joint Grants Scheme are acknowledged. WN MacPherson is supported by an EPSRC Advanced Research Fellowship

    Managing the delivery of iconic football stadiums in England

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    The English football premier league has become the most popular sports league in the world; with ardent fans and audiences all over the world. The potential business opportunities that this growth holds have therefore attracted investors who are keen to buy shares in the clubs and sign up the best footballers that money can buy. Underpinning the growth in all of the premier league clubs is a desire to make a distinct statement of identity as part of a competitive strategy. One way to achieve this is through the design and construction of iconic football stadiums. This paper explores the specific project management challenges associated with delivery of iconic football stadiums in England and draws lessons for the management of similar iconic infrastructure projects. A study of project management best practice and some case studies shows that key issues which are common to these projects are centred on design management; choice of procurement route; client management; and stakeholder expectation management. These issues are not necessarily unique to the project management of iconic football stadiums but are amplified by the context of these projects. The emphasis on iconic status in a competitive market also means that stadium projects should be conceived and delivered in the context of other strategic projects which should be clearly understood by the project management team
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