3,302 research outputs found
Comments on Unified dark energy and dark matter from a scalar field different from quintessence
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
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
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 -function for the Hubble data, we obtain
km/sMpc, for the asymptotic equation of state and . The estimated values of 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
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
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 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
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
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
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
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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