The XRF080109-SN2008D and a decade of GRB-Jet-SN connection

Last and nearest GRB-XRF 080109 has been an exceptional lesson on GRB nature. After a decade (since 25 April 08) we know that Supernovae may often contain a Jet. Its persistent activity may shine on axis as a GRBs. Such a persistent, thin beamed gamma jet may be powered by either a BH (Black Holes) or Pulsars. Late stages of these jets may loose the SN traces and appear as a short GRB or a long orphan GRB (depending on jet angular velocity and view angle). XRF are peripherical viewing of the jets. These precessing and spinning gamma jet are originated by Inverse Compton and-or Synchrotron Radiation at pulsars or micro-quasars sources, by ultra-relativistic electrons. These Jets are most powerful at Supernova birth, blazing, once on axis, to us and flashing GRB detector. The trembling of the thin jet explains naturally the observed erratic multi-explosive structure of different GRBs. The jets are precessing (by binary companion or inner disk asymmetry) and decaying by power on time scales of few hours, but they keep staying inside the observer cone view only a few seconds duration times (GRB); the jet is thinner in gamma and wider in X band. This explain the wider and longer X GRB afterglow duration and the rare presence of X-ray precursors.Comment: 11 pages, 12 figure

Mitigation strategies in densely urbanized contexts: The case study of a historical district in Naples

The design of our cities, their planning, and management must be increasingly oriented towards sustainability, identifying solutions that can systemically address problems on a city scale, namely urban heat islands, rainwater runoff, storms, and acoustic issues. This study begins by evaluating the impact of a green area on pedestrian comfort in the historical center of Naples, employing an experimental and numerical approach. Temperature, relative humidity, and CO2 concentration were measured at three significant points in a historical quarter in "Chiaia"district (Naples): a) in the center of the square "Piazza del Martiri"in the sun, b) in the center of the same square in the shade, and c) in the shade of the vegetation, under the effect of transpiration of deep trees. Then, these measures are used for the calibration of a numerical model developed in an environmental analysis software. The numerical approach has been used to predict the impact of possible mitigation scenarios, by increasing the vegetation and varying the density of the canopy, using non-white cool materials for the urban surfaces and for the facades and roofs of the surrounding historical buildings, and adding fountains. These strategies have a positive effect on urban temperatures and outdoor comfort, in densely urbanized contexts. The findings are finally used to identify the best design solutions, to improve pedestrian comfort and reduce the urban heat, without affecting the historical value of the urban district