Upper limit on the diffuse flux of ultrahigh energy tau neutrinos from the Pierre Auger Observatory

The surface detector array of the Pierre Auger Observatory is sensitive to Earth-skimming tau neutrinos that interact in Earth's crust. Tau leptons from nu(tau) charged-current interactions can emerge and decay in the atmosphere to produce a nearly horizontal shower with a significant electromagnetic component. The data collected between 1 January 2004 and 31 August 2007 are used to place an upper limit on the diffuse flux of nu(tau) at EeV energies. Assuming an E(nu)(-2) differential energy spectrum the limit set at 90% C. L. is E(nu)(2)dN(nu tau)/dE(nu) < 1: 3 x 10(-7) GeV cm(-2) s(-1) sr(-1) in the energy range 2 x 10(17) eV< E(nu) < 2 x 10(19) eV.

Limit on the diffuse flux of ultrahigh energy tau neutrinos with the surface detector of the Pierre Auger Observatory

Data collected at the Pierre Auger Observatory are used to establish an upper limit on the diffuse flux of tau neutrinos in the cosmic radiation. Earth-skimming nu(tau) may interact in the Earth's crust and produce a tau lepton by means of charged-current interactions. The tau lepton may emerge from the Earth and decay in the atmosphere to produce a nearly horizontal shower with a typical signature, a persistent electromagnetic component even at very large atmospheric depths. The search procedure to select events induced by tau decays against the background of normal showers induced by cosmic rays is described. The method used to compute the exposure for a detector continuously growing with time is detailed. Systematic uncertainties in the exposure from the detector, the analysis, and the involved physics are discussed. No tau neutrino candidates have been found. For neutrinos in the energy range 2x10(17) eV < E(nu)< 2x10(19) eV, assuming a diffuse spectrum of the form E(nu)(-2), data collected between 1 January 2004 and 30 April 2008 yield a 90% confidence-level upper limit of E(nu)(2)dN(nu tau)/dE(nu)< 9x10(-8) GeV cm(-2) s(-1) sr(-1).

MOND virial theorem applied to a galaxy cluster

Large values for the mass-to-light ratio (ϒ) in self-gravitating systems is one of the most important evidences of dark matter. We propose a expression for the mass-to-light ratio in spherical systems using MOND. Results for the COMA cluster reveal that a modification of the gravity, as proposed by MOND, can reduce significantly this value.

AQUILINO RIBEIRO AND THE MODERNISTS - PORTRAITS OF THE FIRST PORTUGUESE REPUBLIC

Portuguese version:

Owner portraits and heraldry in the "Lamoignon Hours"

Because of the distance in time and the lack of testifying documents, one should be extremely careful when labelling portraits in medieval books of hours as donor portraits or owner portraits. There are, however, manuscripts that reveal their first owner within their decorative programme, and the Lamoignon Hours (Lisbon, Gulbenkian, ms LA 237) is one of these. This article aims to discuss the iconography of the three portraits found on f.165v, f.202v and f.286v, as well as the relevance of portraiture and heraldic insignia in books of hours and the significance of such content to the original owner and to those who possessed the book afterwards.

The London journal of botany : containing figures and descriptions of such plants as recommend themselves by their novelty, rarity, history, or uses : together with botanical notices and information and and occasional portraits and memoirs of eminent botanists.

v.2 (1843)

The London journal of botany : containing figures and descriptions of such plants as recommend themselves by their novelty, rarity, history, or uses : together with botanical notices and information and and occasional portraits and memoirs of eminent botanists.

v.3 (1844)

The London journal of botany : containing figures and descriptions of such plants as recommend themselves by their novelty, rarity, history, or uses : together with botanical notices and information and and occasional portraits and memoirs of eminent botanists.

v.4 (1845)

The London journal of botany : containing figures and descriptions of such plants as recommend themselves by their novelty, rarity, history, or uses : together with botanical notices and information and and occasional portraits and memoirs of eminent botanists.

v.5 (1846)

The London journal of botany : containing figures and descriptions of such plants as recommend themselves by their novelty, rarity, history, or uses : together with botanical notices and information and and occasional portraits and memoirs of eminent botanists.

v.6 (1847)

The London journal of botany : containing figures and descriptions of such plants as recommend themselves by their novelty, rarity, history, or uses : together with botanical notices and information and and occasional portraits and memoirs of eminent botanists.

v.7 (1848)