5,285 research outputs found
Nos\'e-Hoover Dynamics in Quantum Phase Space
Thermal fluctuations in time-dependent quantum processes are treated by a
constant-temperature generalization of Wigner's formulation of quantum
mechanics in phase space. To this end, quantum Nos\`e-Hoover dynamics is
defined by generalizing the Moyal bracket. Computational applications of the
formalism, together with further theoretical developments, are discussed.Comment: 4 pages, no figure
An orientable time of flight detector for cosmic rays
Cosmic ray studies, in particular UHECR, can be in general supported by a
directional, easy deployable, simple and robust detector. The design of this
detector is based on the time of flight between two parallel tiles of
scintillator, to distinguish particle passing through in opposite directions;
by fine time resolution and pretty adjustable acceptance it is possible to
select upward(left)/downward(right) cosmic rays. It has been developed for an
array of detectors to measure upward from Earth-Skimming neutrino events
with energy above . The properties and performances of the detector
are discussed. Test results from a high noise environment are presented.Comment: 4 pages, Nuclear Instruments and methods, Proceedings Ricap0
Test results of a prototype designed to detect horizontal cosmic ray flux
In this paper we report test results from a prototype designed to detect
muons from horizontal air shower at large zenith angle,
. To detect horizontal tracks and their directions we
select them according the muon vertical equivalent charge and we measure the
time of flight with a time resolution of 800 ps. Several measurements are
collected at different zenith angles. The background studies performed with two
modules show that the main source is due to tracks crossing the module at the
same time. The upper limit of background flux for a single twin module is
estimated to be . We estimated the
size of the surface array necessary to detect the shower flux of the order of
if originated by Tau Air-Showers
secondaries of GZK neutrino Tau below the horizons.Comment: 12 pages, 13 figure
Deterministic constant-temperature dynamics for dissipative quantum systems
A novel method is introduced in order to treat the dissipative dynamics of
quantum systems interacting with a bath of classical degrees of freedom. The
method is based upon an extension of the Nos\`e-Hoover chain (constant
temperature) dynamics to quantum-classical systems. Both adiabatic and
nonadiabatic numerical calculations on the relaxation dynamics of the
spin-boson model show that the quantum-classical Nos\`e-Hoover chain dynamics
represents the thermal noise of the bath in an accurate and simple way.
Numerical comparisons, both with the constant energy calculation and with the
quantum-classical Brownian motion treatment of the bath, show that the
quantum-classical Nos\`e-Hoover Chain dynamics can be used to introduce
dissipation in the evolution of a quantum subsystem even with just one degree
of freedom for the bath. The algorithm can be computationally advantageous in
modeling, within computer simulation, the dynamics of a quantum subsystem
interacting with complex molecular environments.Comment: Revised versio
A proposito di Mafia Capitale. Spunti per tipizzare il fenomeno mafioso nei sistemi di common law
Il presente articolo si puĂČ intendere come una continuazione del dibattito su Mafia Capitale iniziato sul II numero di questa rivista da Nando Dalla Chiesa. Lâarticolo intende portare avanti il dibattito sullâimportanza che il processo di Mafia Capitale potrebbe avere sul piano teorico, oltre che pratico, per la concettualizzazione del fenomeno mafioso in chiave sempre piĂč contemporanea e fuori dallâItalia. Partendo dalle considerazioni fatte da Dalla Chiesa, e tramite unâanalisi di alcuni profili problematici della concettualizzazione del fenomeno mafioso allâestero, in questo articolo si sostiene che si puĂČ giĂ utilizzare lâimpianto accusatorio di Mafia Capitale per una tipizzazione di una sintomatologia mafiosa condivisibile anche oltre lâItalia. Tale tipizzazione permette di abbandonare stereotipi sulla mafia come fenomeno (solo) italiano (o al massimo statunitense) che spesso ritardano o impediscono lâeffettivo riconoscimento di forme mafiose allâestero
Serious, therefore organised? A critique of the emerging "cyber-organised crime" rhetoric in the United Kingdom
This paper, based on discourse analysis of policy documents, departs from a critique of the juxtaposition of the terms "serious" and "organised" in policies against organised crime in the UK. The conceptualisation of organised crime as national security threat supports our hypothesis that a similar critique can be applied to the emerging narrative of cyber-organised crime in the country. We argue that, whereby organised crime has become essentially "serious" as consequence of its characterisation as a national security threat, cyber crime is becoming "organised" in the policy narrative because of its seriousness. The seriousness and organisation of cyber crime justifies its inclusion within the national security agenda, thus accessing the procedural benefits of criminal intelligence assigned to national security threats. The implications associated to the evolution of such narratives in policy-making need to be assessed while policies are still developing
Killing by lung cancer or by diabetes? The trade-off between smoking and obesity
As the prevalence of smoking has decreased to below 20%, health practitioners interest has shifted towards the prevalence of obesity, and reducing it is one of the major health challenges in decades to come. In this paper we study the impact that the final product of the anti-smoking campaign, that is, smokers quitting the habit, had on average weight in the population. To these ends, we use data from the Behavioral Risk Factors Surveillance System, a large series of independent representative cross-sectional surveys. We construct a synthetic panel that allows us to control for unobserved heterogeneity and we exploit the exogenous changes in taxes and regulations to instrument the endogenous decision to give up the habit of smoking. Our estimates, are very close to estimates issued in the â90s by the US Department of Health, and indicate that a 10% decrease in the incidence of smoking leads to an average weight increase of 2.2 to 3 pounds, depending on choice of specification. In addition, we find evidence that the effect overshoots in the short run, although a significant part remains even after two years. However, when we split the sample between men and women, we only find a significant effect for men. Finally, the implicit elasticity of quitting smoking to the probability of becoming obese is calculated at 0.58. This implies that the net benefit from reducing the incidence of smoking by 1% is positive even though the cost to society is $0.6 billions.
- âŠ