3,302 research outputs found

    Comments on Unified dark energy and dark matter from a scalar field different from quintessence

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    In a recent paper by C. Gao, M. Kunz, A. Liddle and D. Parkinson [arXiv:0912.0949], the unification of dark matter and dark energy was explored within a theory containing a scalar field of non-Lagrangian type. This scalar field, different from the classic quintessence, can be obtained from the scalar field representation of an interacting two-fluid mixture described in the paper by L.P. Chimento and M. Forte [arXiv:0706.4142

    Progress in Small x Resummation

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    I review recent theoretical progress in the resummation of small x contributions to the evolution of parton distributions, in view of its potential significance for accurate phenomenology at future colliders. I show that a consistent perturbative resummation of collinear and energy logs is now possible, and necessary if one wishes to use recent NNLO results in the HERA kinematic region.Comment: 8 pages, 6 figures, LaTeX with IJMPA document class, invited plenary talk at the conference on QCD and hadronic physics, Beijing 200

    Holographic dark energy linearly interacting with dark matter

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    We investigate a spatially flat Friedmann-Robertson-Walker (FRW) cosmological model with cold dark matter coupled to a modified holographic Ricci dark energy through a general interaction term linear in the energy densities of dark matter and dark energy, the total energy density and its derivative. Using the statistical method of χ2\chi^2-function for the Hubble data, we obtain H0=73.6H_0=73.6km/sMpc, ωs=−0.842\omega_s=-0.842 for the asymptotic equation of state and zacc=0.89 z_{acc}= 0.89 . The estimated values of Ωc0\Omega_{c0} which fulfill the current observational bounds corresponds to a dark energy density varying in the range 0.25R < \ro_x < 0.27R.Comment: March 2012. 6 pp., 6 figures. Note: To appear in the proceedings of the CosmoSul conference, held in Rio de Janeiro, Brazil, 01-05 august of 201

    BFKL at NNLO

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    We present a recent determination of an approximate expression for the O(alpha_s^3) contribution chi_2 to the kernel of the BFKL equation. This includes all collinear and anticollinear singular contributions and is derived using duality relations between the GLAP and BFKL kernels.Comment: 8 pages. Talk presented at 12th International Conference on Elastic and Diffractive Scattering: Forward Physics and QCD, Hamburg, DESY, Germany, 21-25 May 200

    Ultrashort Lifetime Expansion for Indirect Resonant Inelastic X-ray Scattering

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    In indirect resonant inelastic X-ray scattering (RIXS) an intermediate state is created with a core-hole that has a ultrashort lifetime. The core-hole potential therefore acts as a femtosecond pulse on the valence electrons. We show that this fact can be exploited to integrate out the intermediate states from the expressions for the scattering cross section. By this we obtain an effective scattering cross section that only contains the initial and final scattering states. We derive in detail the effective cross section which turns out to be a resonant scattering factor times a linear combination of the charge response function S(q,ω)S({\bf q},\omega) and the dynamic longitudinal spin density correlation function. This result is asymptotically exact for both strong and weak local core-hole potentials and ultrashort lifetimes. The resonant scattering pre-factor is shown to be weakly temperature dependent. We also derive a sum-rule for the total scattering intensity and generalize the results to multi-band systems. One of the remarkable outcomes is that one can change the relative charge and spin contribution to the inelastic spectral weight by varying the incident photon energy.Comment: 9 pages, 3 figures embedde

    The eradication of insect pests - Some observations on the Argentine Ant campaign in Western Australia

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    To an entomologist, and especially an economic entomologist, the word eradication means the destruction of all members of a species of insect in any particular area. It means the perfection of a project in the control of an economic insect pest. Adapted from an address given before the Australian Institute of Agricultural Science (West Australian Branch), by the Retiring President (Mr. P. N. Forte, B.Sc, Agric.) on April 13, 1956

    Winter pests in the pasture

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    ALTHOUGH the pests concerned in attacking winter pastures are known to most farmers a discussion of their control and relative importance will not be out of place. The principal pests concerned fall into two groups. Firstly the red-legged earth mite and lucerne flea whose attacks are most noticeable soon after germination and secondly a group of caterpillars which appear about the same time and whose attack is not noticed until a large amount of damage has been done

    Parametric thermal analysis for the optimization of Double Walled Tubes layout in the Water Cooled Lithium Lead inboard blanket of DEMO fusion reactor

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    Within the roadmap that will lead to the nuclear fusion exploitation for electric energy generation, the construction of a DEMOnstration (DEMO) reactor is, probably, the most important milestone to be reached since it will demonstrate the technological feasibility and economic competitiveness of an industrial-scale nuclear fusion reactor. In order to reach this goal, several European universities and research centres have joined their efforts in the EUROfusion action, funded by HORIZON 2020 UE programme. Within the framework of EUROfusion research activities, ENEA and University of Palermo are involved in the design of the Water-Cooled Lithium Lead Breeding Blanket (WCLL BB), that is one of the two BB concepts under consideration to be adopted in the DEMO reactor. It is mainly characterized by a liquid lithium-lead eutectic alloy acting as breeder (lithium) and neutron multiplier (lead), as well as by subcooled pressurized water as coolant. Two separate circuits, both characterized by a pressure of 15.5 MPa and inlet/outlet temperatures of 295 °C/328 °C, are deputed to cool down the First Wall (FW) and the Breeder Zone (BZ). The former consists in a system of radial-toroidal-radial C-shaped squared channels where countercurrent water flow occurs while the latter relies in the use of bundles of poloidal-radial Double Walled Tubes (DWTs) housed within the breeder. A parametric thermal study has been carried out in order to assess the best DWTs' layout assuring that the structural material maximum temperature does not overcome the allowable limit of 550 °C and that the overall coolant thermal rise fulfils the design target value of 33 °C. The study has been performed following a theoretical-numerical approach based on the Finite Element Method (FEM) and adopting the quoted Abaqus FEM code. Main assumptions and models together with results obtained are herewith reported and critically discussed

    The control of mealy bug on vines in Western Australia

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    The mealy bug (Pseudococcus maritimus Ehr.) was first recorded on vines in Western Australia in 1898 (A. M. Lea, 1898). Since then it has been reported present in certain years in large numbers with consequent loss of quality in the vine products
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