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Search Results: 1 - 10 of 2557 matches for " Giorgio Giovanelli "
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Quantum bit error rate in modeled atmospheres
Nicolo' Antonietti,Marina Mondin,Fred Daneshgaran,Giorgio Giovanelli,Ivan Kostadinov,Bruno Lunelli,Giorgio Brida,Marco Genovese,Marco Gramegna
Physics , 2008,
Abstract: The quantum bit error rate is a key quantity in quantum communications. If the quantum channel is the atmosphere, the information is usually encoded in the polarization of a photon. A link budget is required, which takes into account the depolarization of the photon after its interaction with the atmosphere as well as absorption, scattering and atmospheric emissions. An experimental setup for the reproduction of a simple model of the atmosphere is used to evaluate the quantum bit error rate in a BB84 protocol and the results are presented. This result represents a first step toward the realization of an optical bench experiment where atmospheric effects are simulated and controlled for reproducing the effects on a quantum channel in different meteorological situations.
On a scarab from Colle del Forno: some considerations on the globular style production A proposito di uno scarabeo da Colle del Forno: alcune considerazioni sulla produzione di stile globulare
Enrico Giovanelli
Lanx , 2010, DOI: 10.6092/2035-4797/616
Abstract: The scarab from Colle del Forno necropolis presented in this note gives the opportunity for some very brief considerations regarding to the globolo-style production, considering also the recent synthesis work by Ulf Hannson, that is at now a very useful update regarding to stylistic, formal, iconographical questions, to the production aspects and represents as well a good integration of the corpus already build up by Peter Zazoff. L’esemplare di scarabeo dalla necropoli di Colle del Forno presentato in questa sede fornisce lo spunto per alcune brevissime considerazioni in merito alla produzione di stile globulare anche a fronte del recente lavoro di sintesi di U. Hannson sul tema che costituisce ad oggi un utilissimo aggiornamento sulle questioni stilistiche, formali, iconografiche, sugli aspetti produttivi nonché una discreta integrazione del corpus che era già stato apprestato da Peter Zazoff.
"Teaching the Design History of the Motorcycle"
Leland Giovanelli
International Journal of Motorcycle Studies , 2006,
Deviations from Hubble Flow in the Local Universe
Riccardo Giovanelli
Physics , 1996,
Abstract: Reviews observational situation in the measurement of peculiar velocities in the local universe. Emphasis is placed on such topics as: Do spirals and ellipticals yield the same peculiar velocity field? What is the cluster velocity distribution function? What is the convergence depth of the local universe, as seen by inspection of motions of clusters and of field galaxies? Are there large-scale bulk flows? A reconstruction of the density field and an estimate of the Hubble constant are also given.
The I-Band Tully-Fisher Relation and the Hubble Constant
Riccardo Giovanelli
Physics , 1996,
Abstract: The application of the I band Tully--Fisher relation towards determining the Hubble constant is reviewed, with particular attention to the impact of scatter and bias corrections in the relation. A template relation is derived from galaxies in 24 clusters. A subset of 14 clusters with cz ~ 4000 to 9000 km/s is used as an inertial frame to define the velocity zero point of the relation. Twelve galaxies with Cepheid distances are used to establish the absolute magnitude scale of the Tully--Fisher relation, and thus to determine a value of H_not = 70\pm5 km/s/Mpc. Estimates of the peculiar velocities of the Virgo and Fornax clusters are also given. Assuming that the distance to Fornax is 18.2 Mpc (N1365), H_not = 76\pm8 km/s/Mpc. Assuming that Virgo lies at 17.4 Mpc (M100, N4496, N4639), H_not = 67\pm8 km/s/Mpc.
Spiral Galaxies and the Peculiar Velocity Field
R. Giovanelli
Physics , 1998,
Abstract: Monopole and dipole signatures of the peculiar velocity field as derived from the SFI sample of field spirals and the SCI and SC2 samples of cluster spirals are presented. The monopole exhibits no evidence of a `Hubble bubble' within 7000 km/s as suggested by Zehavi et al. (1998); the dipole of the reflex motion of the Local Group converges to the CMB dipole within less than 6000 km/s, and remains consistent with it, when referred to the reference frame constituted by the SC2 cluster sample, which extends to 20,000 km/s.
The Void Phenomenon Revisited
Riccardo Giovanelli
Physics , 2009,
Abstract: The Void Phenomenon consists in the apparent discrepancy between the number of observed dwarf halos in cosmic voids and that expected from CDM simulations. We approach the problem considering the challenging prospects of detecting field dwarf systems with halo masses < 10^9 solar, via their possible HI emission. A brief review of recent work is followed by preliminary results from the ALFALFA survey, which suggest the possibility, but not yet the proof, that such objects may have been already detected towards the outskirts of the Local Group.
Optical Seeing and Infrared Atmospheric Transparency in the Upper Atacama Desert
Riccardo Giovanelli
Physics , 2000,
Abstract: With plans to build a large IR/optical telescope in the Atacama Desert, a site survey campaign has been underway since 1998 to characterize the optical seeing and the IR transparency in the Chajnantor Plateau region. Preliminary results indicate that the Chajnantor region offers excellent astronomical observing conditions in the optical and IR. The region is isolated yet easy to reach, and high quality services are available nearby. We can expect to find: median optical FWHM seeing approaching values of 0.5"--0.6", a percentage of photometric nights of 65% or better, of astronomically useful nights in excess of 80% and median PWV well below 1 mm (with best quartile below 0.5 mm).
On the Scaling Relations of Disk Galaxies
Riccardo Giovanelli
Physics , 2013, DOI: 10.1017/S1743921312021588
Abstract: The physical background of scaling laws of disk galaxies is reviewed. The match between analytically derived and observed scaling laws is briefly discussed. Accurate modeling of the fraction of baryons that end populating a disk, and the conversion efficiency of those into stars, remains a challenging task for numerical simulations. The measurement of rotational velocity tends to be made with criteria of convenience rather than through rigorous definition. And yet, the Tully-Fisher and the disk size vs. rotational velocity relations exhibit surprisingly low scatter. Practical recipes (and costs) to optimize the quality of template relations are considered.
The Dynamics of Wave-Particle Duality  [PDF]
Adriano Orefice, Raffaele Giovanelli, Domenico Ditto
Journal of Applied Mathematics and Physics (JAMP) , 2018, DOI: 10.4236/jamp.2018.69157
Abstract: Both classical and wave-mechanical monochromatic waves may be treated in terms of exact ray-trajectories (encoded in the structure itself of Helmholtz-like equations) whose mutual coupling is the one and only cause of any diffraction and interference process. In the case of Wave Mechanics, de Broglie’s merging of Maupertuis’s and Fermat’s principles (see Section 3) provides, without resorting to the probability-based guidance-laws and flow-lines of the Bohmian theory, the simple law addressing particles along the Helmholtz rays of the relevant matter waves. The purpose of the present research was to derive the exact Hamiltonian ray-trajectory systems concerning, respectively, classical electromagnetic waves, non-relativistic matter waves and relativistic matter waves. We faced then, as a typical example, the numerical solution of non-relativistic wave-mechanical equation systems in a number of numerical applications, showing that each particle turns out to “dances a wave-mechanical dance” around its classical trajectory, to which it reduces when the ray-coupling is neglected. Our approach reaches the double goal of a clear insight into the mechanism of wave-particle duality and of a reasonably simple computability. We finally compared our exact dynamical
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