One of the tasks of the European Commission (EC) under the Euratom Treaty is to collect, validate and provide information about the levels of radioactivity in the environment. In order to offer to the public a more balanced view on the annual dose that it may receive from environmental radioactivity, a few years ago we decided to explore the feasibility of preparing a European Atlas of Natural ...

This article reviews three related topics: the extragalactic background light and its sources, evolution models for the dust absorption and emission in galaxies, and empirical constraints on these transfer processes in nearby starburst galaxies. It is intended that the material presented here will serve as an introduction to this Joint Discussion. 1. Extragalactic Background Light A good place ...

We study the weak convergence (in the high-frequency limit) of the frequency components associated with Gaussian-subordinated, spherical and isotropic random fields. In particular, we provide conditions for asymptotic Gaussianity and we establish a new connection with random walks on the hypergroup ŜO (3) (the dual of SO (3)), which mirrors analogous results previously established for fields de...

We discuss the contribution of the blazar population to the extragalactic background radiation across the electromagnetic (e.m.) spectrum with particular reference to the microwave, hard-X-ray and γ-ray bands. Our estimates are based on a recently derived blazar radio LogN-LogS that was built by combining several radio and multi-frequency surveys. We show that blazar emission integrated over co...

Spectra of density perturbations produced during chaotic innation in scalar-tensor theories of gravity are calculated, taking both adiabatic and isocurva-ture modes into account. Comparing the predicted spectrum of the cosmic microwave background radiation anisotropies with the one observed by the COBE-DMR we calculate constraints on the parameters of these theories, which turn out to be strong...

We describe the results of a hybrid matrix{Monte Carlo calculation of cascading of UHE cosmic rays through the cosmic background radiation elds over cosmological distances. We calculate the-ray and neutrino emission that results from the cascade, as well as the eeect of cascading on the primary spectrum. We discuss the results for various cosmic ray injection spectra.

15 In carbon dioxide (CO2) geological storage, the monitoring of the injected CO2 migration in 16 underground storage is essential to understanding storage process and ensuring storage safety. An 17 effective monitoring system will be required for decades into the future during storage phase to 18 indicate the location where the injected fluids have extended to. A novel radiographic probing 19 ...

Dark energy is one of the mysteries of modern science. It is unlike any known form of matter or energy and has been detected so far only by its gravitational effect of repulsion. Owing to its effects being discernible only at very very large distance scales, dark energy was only detected at the turn of the last century when technology had advanced enough to observe a greater part of the univers...

Abstract We recall Mexican needlets from [5]. We derive an estimate for certain types of Legendre series, which we apply to the statistical properties of Mexican needlets. More precisely, we shall show that, under isotropy and Gaussianity assumptions, the Mexican needlet coefficients of a random field on the sphere are asymptotically uncorrelated, as the frequency parameter goes to infinity. Th...

The Cosmic Microwave Background (CMB), which permeates the entire Universe, is the radiation left over from just 390,000 years after the Big Bang. On very large scales, the CMB radiation field is smooth and isotropic, but the existence of structure in the Universe – stars, galaxies, clusters of galaxies, . . . – suggests that the field should fluctuate on smaller scales. Recent observations, fr...