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Search Results: 1 - 10 of 3882 matches for " Alice Foschini "
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A very singular property
Luigi Foschini
Physics , 2009,
Abstract: By using the Fermi satellite, a group of physicists discovers a new type of gamma-ray active nucleus
Electromagnetic interferences from plasmas generated in meteoroids impacts
Luigi Foschini
Physics , 1998, DOI: 10.1209/epl/i1998-00344-9
Abstract: It is shown that the plasma, generated during an impact of a meteoroid with an artificial satellite, can produce electromagnetic radiation below the microwave frequency range. This interference is shown to exceed local noise sources and might disturb regular satellite operations.
The meteoroid hazard for space navigation
Luigi Foschini
Physics , 1998,
Abstract: Thanks to post-flight analyses of several artificial satellites carried out during last years, the meteoroids hazard for space navigation and in-orbit satellites permanence is now clear. Even if catastrophic impact is a rare event, high meteoroids fluxes can erode and weaken the satellite or space station main structures. However, the main danger seems to be the impact-generated plasma, which can produce electromagnetic interferences, disturbing the on-board electronics.
On the logic of quantum physics and the concept of the time
Luigi Foschini
Physics , 1998,
Abstract: The logic--linguistic structure of quantum physics is analysed. The role of formal systems and interpretations in the representation of nature is investigated. The problems of decidability, completeness, and consistency can affect quantum physics in different ways. Bohr's complementarity is of great interest,because it is a contradictory proposition. We shall see that the flowing of time prevents the birth of contradictions in nature, because it makes a cut between two different, but complementary aspects of the reality.
On the interaction of radio waves with meteoric plasma
Luigi Foschini
Physics , 1998,
Abstract: In this paper, a meteoric plasma is analyzed from a physical viewpoint, with particular emphasis on its interaction with radio waves. The attention is drawn to some macroscopic characteristics of a meteoric plasma and it is shown that the electron-ion collision frequency is not negligible, as commonly thought.
Questions on the concept of time
Luigi Foschini
Physics , 1999,
Abstract: Some notes and questions about the concept of time are exposed. Particular reference is given to the problem in quantum mechanics, in connection with the indeterminacy principle.
Is Science going through a critical stage?
Luigi Foschini
Physics , 1998,
Abstract: The unexpected discoveries at the beginning of the century, particularly thanks to Heisenberg, Bohr, and Godel, has driven the science to drastic changes, opening new, extraordinary, and infinite research fields. After this, many scientists saw, and still today see, a crisis, with dreadful meaning, in the science. However, this crisis is only present in that type of science, driven by determinism, which is strictly linked to the common sense.
Jets (relativistic and non) in astrophysics
Luigi Foschini
Physics , 2010,
Abstract: Let's take stock of the situation on one of the most studied astrophysical phenomena during the latest years: the jets escaping from protostars, stellar singularities, GRB and active galactic nuclei.
Accretion and jet power in active galactic nuclei
Luigi Foschini
Physics , 2011, DOI: 10.1088/1674-4527/11/11/003
Abstract: The classical diagrams of radio loudness and jet power as a function of mass and accretion rate of the central spacetime singularity in active galactic nuclei are reanalyzed by including the data of the recently discovered powerful relativistic jets in Narrow-Line Seyfert 1 Galaxies. The results are studied in the light of the known theories on the relativistic jets, indicating that while the Blandford-Znajek mechanism is sufficient to explain the power radiated by BL Lac Objects, it fails to completely account the power from quasars and Narrow-Line Seyfert 1. This favors the scenario outlined by Cavaliere & D'Elia of a composite jet, with a magnetospheric core plus a hydromagnetic component emerging as the accretion power increases and the disc becomes radiation-pressure dominated. A comparison with Galactic compact objects is also performed, finding some striking similarities, indicating that as the neutron stars are the low-mass jet systems analogue of black holes, the Narrow-Line Seyfert 1 Galaxies are the low-mass counterpart of the blazars.
The Blandford-Znajek theory revisited
Luigi Foschini
Physics , 2012,
Abstract: The Blandford-Znajek theory (1977) is generally studied to understand the generation of powerful relativistic jets. However, it could also give important insights about the feedback between a rotating black hole, its ergosphere, and a surrounding accretion disk. The energy flow between these systems could be understood by studying the BZ power as a function of a slip factor, which in turn is defined as a function of the angular velocity of the black hole and the angular velocity of the magnetic field lines (generally anchored to the disk). The distinct stages could explain the different types of observed AGN (with/without jets), but could also help understanding the evolution of the merging of binary AGN.
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