High-energy γ\gamma-ray emission from GRBs

GRBs are nowadays a rather well understood phenomenon in the soft (KeV-MeV) $\gamma$-ray energy band, while only a few GRBs have been observed at high photon energies (E_{\gamma} \ut > 1 GeV). It is also widely recognized that GRBs accelerate protons to relativistic energies and that dense media are often present nearby the sources. Within this framework we compute in detail the high-energy $\gamma$-ray flux from the decay of neutral pions produced through the interaction of accelerate protons with nucleons in the surrounding medium. We also take into account the local and intergalactic $\gamma$-ray absorption. The presence of magnetic fields around the GRB sources causes the deflection of the accelerated protons and so a temporal spread of the produced high-energy $\gamma$-rays with respect to the signal in the soft $\gamma$-ray band. Moreover, we analyze the possibility to detect the $\gamma$-ray signal in the GeV-TeV energy range by the ARGO detector under construction in Tibet.Comment: 9 pages, 7 figures, abstract shortened, to appear in Astronomy and Astrophysic

On the Maximal Invariant Statistic for Adaptive Radar Detection in Partially-Homogeneous Disturbance with Persymmetric Covariance

This letter deals with the problem of adaptive signal detection in partially-homogeneous and persymmetric Gaussian disturbance within the framework of invariance theory. First, a suitable group of transformations leaving the problem invariant is introduced and the Maximal Invariant Statistic (MIS) is derived. Then, it is shown that the (Two-step) Generalized-Likelihood Ratio test, Rao and Wald tests can be all expressed in terms of the MIS, thus proving that they all ensure a Constant False-Alarm Rate (CFAR).Comment: submitted for journal publicatio

A PROTOCOL OR A SET OF STANDARDS TO GUIDE AGRICULTURAL ECONOMICS RESEARCH

This article examines some difficult decisions that agricultural economists must confront in doing research. Over many years, rules and standards have developed in agricultural economics that guide researchers, providing an underlying framework for research methods. This article deals with applying these seldom discussed guidelines to specific research situations confronted by agricultural economists. With this article, we hope to stimulate a dialogue among agricultural economists about the need for additional, appropriate methodological guidelines in agricultural economics research.Research and Development/Tech Change/Emerging Technologies,