Helioseismology: a fantastic tool to probe the interior of the Sun

Helioseismology, the study of global solar oscillations, has proved to be an extremely powerful tool for the investigation of the internal structure and dynamics of the Sun. Studies of time changes in frequency observations of solar oscillations from helioseismology experiments on Earth and in space have shown, for example, that the Sun's shape varies over solar cycle timescales. In particular, far-reaching inferences about the Sun have been obtained by applying inversion techniques to observations of frequencies of oscillations. The results, so far, have shown that the solar structure is remarkably close to the predictions of the standard solar model and, recently, that the near-surface region can be probed with sufficiently high spatial resolution as to allow investigations of the equation of state and of the solar envelope helium abundance. The same helioseismic inversion methods can be applied to the rotational frequency splittings to deduce with high accuracy the internal rotation velocity of the Sun, as function of radius and latitude. This also allows us to study some global astrophysical properties of the Sun, such as the angular momentum, the grativational quadrupole moment and the effect of distortion induced on the surface (oblateness). The helioseismic approach and what we have learnt from it during the last decades about the interior of the Sun are reviewed here.Comment: 36 page

The PADME experiment at LNF

Massive photon-like particles are predicted in many extensions of the Standard Model. They have interactions similar to the photon, are vector bosons, and can be produced together with photons. The PADME experiment proposes a search for the dark photon ($A'$) in the $e^+e^- \to \gamma A'$ process in a positron-on-target experiment, exploiting the positron beam of the DA$\Phi$NE linac at the Laboratori Nazionali di Frascati, INFN. In one year of running a sensitivity in the relative interaction strength down to $10^{-6}$ is achievable, in the mass region from 2.5 MeV $<M_{A'}<$ 22.5 MeV. The proposed experimental setup and the analysis technique is discussed.Comment: to be published in the DHF2014 proceedings EPJ Web of Conference

The role of Lambda in the cosmological lens equation

The cosmological constant Lambda affects cosmological gravitational lensing. Effects due to Lambda can be studied in the framework of the Schwarzschild-de Sitter spacetime. Two novel contributions, which can not be accounted for by a proper use of angular diameter distances, are derived. First, a term 2m b Lambda/3 has to be added to the bending angle, where "m" is the lens mass and "b" the impact parameter. Second, Lambda brings about a difference in the redshifts of multiple images. Both effects are quite small for real astrophysical systems (contribution to the bending < 0.1 microarcsec and difference in redshift < 10^{-7}).Comment: 4 pages. (Univ. Zuerich); v2: presentation improved, discussion extended, references to papers posted after the v1-version added. In press on Phys. Rev. Let

Polyunsaturated fatty acid-derived lipid mediators and T cell function

Copyright © 2014 Nicolaou, Mauro, Urquhart and Marelli-Berg . This is an open- access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms