21,889 research outputs found

    The BIOEXPLOIT Project

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    The EU Framework 6 Integrated Project BIOEXPLOIT concerns the exploitation of natural plant biodiversity for the pesticide-free production of food. It focuses on the pathogens Phytophthora infestans, Septoria tritici, Blumeria graminis, Puccinia spp. and Fusarium spp. and on the crops wheat, barley, tomato and potato. The project commenced in October 2005, comprises 45 laboratories in 12 countries, and is carried out by partners from research institutes, universities, private companies and small-medium enterprises. The project has four strategic objectives covered in eight sub-projects. These objectives relate to (i) understanding the molecular components involved in durable disease resistance, (ii) exploring and exploiting the natural biodiversity in disease resistance, (iii) accelerating the introduction of marker-assisted breeding and genetic engineering in the EU plant breeding industry, and (iv) coordinating and integrating resistance breeding research, providing training in new technologies, disseminating the results, and transferring knowledge and technologies to the industry

    Strong coupling constant from bottomonium fine structure

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    From a fit to the experimental data on the bbˉb\bar{b} fine structure, the two-loop coupling constant is extracted. For the 1P state the fitted value is αs(μ1)=0.33±0.01(exp)±0.02(th)\alpha_s(\mu_1) = 0.33 \pm 0.01(exp)\pm 0.02 (th) at the scale μ1=1.8±0.1\mu_1 = 1.8 \pm 0.1 GeV, which corresponds to the QCD constant Λ(4)(2loop)=338±30\Lambda^{(4)}(2-loop) = 338 \pm 30 MeV (n_f = 4) and αs(MZ)=0.119±0.002.Forthe2Pstatethevalue\alpha_s(M_Z) = 0.119 \pm 0.002. For the 2P state the value \alpha_s(\mu_2) = 0.40 \pm 0.02(exp)\pm 0.02(th)atthescale at the scale \mu_2 = 1.02 \pm 0.2GeVisextracted,whichissignificantlylargerthaninthepreviousanalysisofFulcher(1991)andHalzen(1993),butabout30smallerthanthevaluegivenbystandardperturbationtheory.Thisvalue GeV is extracted, which is significantly larger than in the previous analysis of Fulcher (1991) and Halzen (1993), but about 30% smaller than the value given by standard perturbation theory. This value \alpha_s(1.0) \approx 0.40canbeobtainedintheframeworkofthebackgroundperturbationtheory,thusdemonstratingthefreezingof can be obtained in the framework of the background perturbation theory, thus demonstrating the freezing of \alpha_s.Therelativisticcorrectionsto. The relativistic corrections to \alpha_s$ are found to be about 15%.Comment: 18 pages LaTe

    The leptonic widths of high ψ\psi-resonances in unitary coupled-channel model

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    The leptonic widths of high ψ\psi-resonances are calculated in a coupled-channel model with unitary inelasticity, where analytical expressions for mixing angles between (n+1)\,^3S_1 and n\,^3D_1 states and probabilities ZiZ_i of the ccˉc\bar c component are derived. Since these factors depend on energy (mass), different values of mixing angles θ(ψ(4040))=27.7\theta(\psi(4040))=27.7^\circ and θ(ψ(4160))=29.5\theta(\psi(4160))=29.5^\circ, Z1(ψ(4040))=0.76Z_1\,(\psi(4040))=0.76, and Z2(ψ(4160))=0.62Z_2\,(\psi(4160))=0.62 are obtained. It gives the leptonic widths Γee(ψ(4040))=Z11.17=0.89\Gamma_{ee}(\psi(4040))=Z_1\, 1.17=0.89~keV, Γee(ψ(4160))=Z20.76=0.47\Gamma_{ee}(\psi(4160))=Z_2\, 0.76=0.47~keV in good agreement with experiment. For ψ(4415)\psi(4415) the leptonic width Γee(ψ(4415))= 0.55\Gamma_{ee}(\psi(4415))=~0.55~keV is calculated, while for the missing resonance ψ(4510)\psi(4510) we predict M(ψ(4500))=(4515±5)M(\psi(4500))=(4515\pm 5)~MeV and Γee(ψ(4510))0.50\Gamma_{ee}(\psi(4510)) \cong 0.50~keV.Comment: 10 pages, 6 references corrected, some new material adde

    Higher excitations of the DD and DsD_s mesons

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    The masses of higher D(nL)D(nL) and Ds(nL)D_s(nL) excitations are shown to decrease due to the string contribution, originating from the rotation of the QCD string itself: it lowers the masses by 45 MeV for L=2(n=1)L=2 (n=1) and by 65 MeV for L=3(n=1)L=3 (n=1). An additional decrease 100\sim 100 MeV takes place if the current mass of the light (strange) quark is used in a relativistic model. For Ds(13D3)D_s(1\,{}^3D_3) and Ds(2P1H)D_s(2P_1^H) the calculated masses agree with the experimental values for Ds(2860)D_s(2860) and Ds(3040)D_s(3040), and the masses of D(21S0)D(2\,{}^1S_0), D(23S1)D(2\,{}^3S_1), D(13D3)D(1\,{}^3D_3), and D(1D2)D(1D_2) are in agreement with the new BaBar data. For the yet undiscovered resonances we predict the masses M(D(23P2))=2965M(D(2\,{}^3P_2))=2965 MeV, M(D(23P0))=2880M(D(2\,{}^3P_0))=2880 MeV, M(D(13F4))=3030M(D(1\,{}^3F_4))=3030 MeV, and M(Ds(13F2))=3090M(D_s(1\,{}^3F_2))=3090 MeV. We show that for L=2,3L=2,3 the states with jq=l+1/2j_q=l+1/2 and jq=l1/2j_q=l-1/2 (J=lJ=l) are almost completely unmixed (ϕ1\phi\simeq -1^\circ), which implies that the mixing angles θ\theta between the states with S=1 and S=0 (J=LJ=L) are θ40\theta\approx 40^\circ for L=2 and 42\approx 42^\circ for L=3.Comment: 22 pages, no figures, 4 tables Two references and corresponding discussion adde

    The heavy-quark pole masses in the Hamiltonian approach

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    From the fact that the nonperturbative self-energy contribution CSEC_{\rm SE} to the heavy meson mass is small: CSE(bbˉ)=0C_{\rm SE}(b\bar{b})=0; CSE(ccˉ)40C_{\rm SE}(c\bar{c})\cong -40 MeV \cite{ref.01}, strong restrictions on the pole masses mbm_b and mcm_c are obtained. The analysis of the bbˉb\bar{b} and the ccˉc\bar{c} spectra with the use of relativistic (string) Hamiltonian gives mbm_b(2-loop)=4.78±0.05=4.78\pm 0.05 GeV and mcm_c(2-loop)=1.39±0.06=1.39 \pm 0.06 GeV which correspond to the MSˉ\bar{\rm MS} running mass mˉb(mˉb)=4.19±0.04\bar{m}_b(\bar{m}_b)=4.19\pm 0.04 GeV and mˉc(mˉc)=1.10±0.05\bar{m}_c(\bar{m}_c)=1.10\pm 0.05 GeV. The masses ωc\omega_c and ωb\omega_b, which define the heavy quarkonia spin structure, are shown to be by 200\sim 200 MeV larger than the pole ones.Comment: 18 pages, no figures, 8 table

    Light meson radial Regge trajectories

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    A new physical mechanism is suggested to explain the universal depletion of high meson excitations. It takes into account the appearance of holes inside the string world sheet due to qqˉq\bar{q} pair creation when the length of the string exceeds the critical value R11.4R_1 \simeq 1.4 fm. It is argued that a delicate balance between large NcN_c loop suppression and a favorable gain in the action, produced by holes, creates a new metastable (predecay) stage with a renormalized string tension which now depends on the separation r. This results in smaller values of the slope of the radial Regge trajectories, in good agreement with the analysis of experimental data in [Ref.3]Comment: 25 pages, 1 figur

    The ccˉc\bar c interaction above threshold and the radiative decay X(3872)J/ψγX(3872)\rightarrow J/\psi\gamma

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    Radiative decays of X(3872)X(3872) are studied in single-channel approximation (SCA) and in the coupled-channel (CC) approach, where the decay channels DDˉD\bar D^* are described with the string breaking mechanism. In SCA the transition rate Γ~2=Γ(23P1ψγ)=71.8\tilde{\Gamma}_2=\Gamma(2\,{}^3P_1 \rightarrow \psi\gamma)=71.8~keV and large Γ~1=Γ(23P1J/ψγ)=85.4\tilde{\Gamma}_1=\Gamma(2\,{}^3P_1\rightarrow J/\psi\gamma)=85.4~keV are obtained, giving for their ratio the value Rψγ~=Γ~2Γ~1=0.84\tilde{R_{\psi\gamma}}=\frac{\tilde{\Gamma}_2}{\tilde{\Gamma}_1}=0.84. In the CC approach three factors are shown to be equally important. First, the admixture of the 13P11\,{}^3P_1 component in the normalized wave function of X(3872)X(3872) due to the CC effects. Its weight cX(ER)=0.200±0.015c_{\rm X}(E_{\rm R})=0.200\pm 0.015 is calculated. Secondly, the use of the multipole function g(r)g(r) instead of rr in the overlap integrals, determining the partial widths. Thirdly, the choice of the gluon-exchange interaction for X(3872)X(3872), as well as for other states above threshold. If for X(3872)X(3872) the gluon-exchange potential is taken the same as for low-lying charmonium states, then in the CC approach Γ1=Γ(X(3872)J/ψγ)3\Gamma_1= \Gamma(X(3872)\rightarrow J/\psi\gamma) \sim 3~keV is very small, giving the large ratio Rψγ=B(X(3872)ψ(2S)γ)B(X(3872)J/ψγ)1.0R_{\psi\gamma}=\frac{\mathcal{B}(X(3872)\rightarrow \psi(2S)\gamma)}{\mathcal{B}(X(3872)\rightarrow J/\psi\gamma)}\gg 1.0. Arguments are presented why the gluon-exchange interaction may be suppressed for X(3872)X(3872) and in this case Γ1=42.7\Gamma_1=42.7~keV, Γ2=70.5\Gamma_2= 70.5~keV, and Rψγ=1.65R_{\psi\gamma}=1.65 are predicted for the minimal value cX(min)=0.185c_{\rm X}({\rm min})=0.185, while for the maximal value cX=0.215c_{\rm X}=0.215 we obtained Γ1=30.8\Gamma_1=30.8~keV, Γ2=73.2\Gamma_2=73.2~keV, and Rψγ=2.38R_{\psi\gamma}=2.38, which agrees with the LHCb data.Comment: 12 pages, no figure

    Health Planner Pigs as an Instrument for Monitoring and Evaluation of Animal Health Care on Pig Farms

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    In order to support animal health care on pig farms a Health Planner Pigs has been developed. In 1998 the practical value of the system was tested under field condition on pig farms. The Health Planner proved to be a valuable instrument for monitoring and evaluating animal health on pig farms. Due to the promising results of the field experiment, the Dutch Farmers Organisation (LTO-Nederland) in 1999 adopted the system and coordinates its adaptation and introduction into practice. In 2001, veterinarians and farm advisers has been educated in using the Health Planner. Some parts of the Health Planner will be automised and linked to existing farm management information systems. In 2002, farmers will be educated in the use of it.Farm Management, Livestock Production/Industries,

    Flexible nurse staffing based on hourly bed census predictions

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    Workload on nursing wards depends highly on patient arrivals and patient lengths of stay, which are both inherently variable. Predicting this workload and staffing nurses accordingly is essential for guaranteeing quality of care in a cost effective manner. This paper introduces a stochastic method that uses hourly census predictions to derive efficient nurse staffing policies. The generic analytic approach minimizes staffing levels while satisfying so-called nurse-to-patient ratios. In particular, we explore the potential of flexible staffing policies which allow hospitals to dynamically respond to their fluctuating patient population by employing float nurses. The method is applied to a case study of the surgical inpatient clinic of the Academic Medical Center (AMC) Amsterdam. This case study demonstrates the method's potential to study the complex interaction between staffing requirements and several interrelated planning issues such as case mix, care unit partitioning and size, and surgical block planning. Inspired by the numerical results, the AMC decided that this flexible nurse staffing methodology will be incorporated in the redesign of the inpatient care operations during the upcoming years
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