Density Distribution of a Bose-Einstein Condensate of Photons in a Dye-Filled Microcavity

The achievement of Bose-Einstein condensation of photons (phBEC) in a dye-filled microcavity has led to a renewed interest in the density distribution of the ideal Bose gas in a two-dimensional harmonic oscillator. We present measurements of the radial profile of photons inside the microcavity below and above the critical point for phBEC with a good signal-to-noise ratio. We obtain a good agreement with theoretical profiles obtained using exact summation of eigenstates.Comment: 5 pages, 4 figure

Density Distribution of a Bose-Einstein Condensate of Photons in a Dye-Filled Microcavity

The achievement of Bose-Einstein condensation of photons (phBEC) in a dye-filled microcavity has led to a renewed interest in the density distribution of the ideal Bose gas in a two-dimensional harmonic oscillator. We present measurements of the radial profile of photons inside the microcavity below and above the critical point for phBEC with a good signal-to-noise ratio. We obtain a good agreement with theoretical profiles obtained using exact summation of eigenstates.Comment: 5 pages, 4 figure

La sécurité du jeu et le jeu de la sécurité : piratage, loi et politique publique

Le présent rapport est l’objet d’une étude du lien entre les organisations criminelles et le contrôle social dans le domaine de la criminalité informatique. D’abord, nous examinerons quelques attaques montées contre des appareils de jeu électronique. Ensuite, nous analyserons de quelle façon ces cyberattaques ont été commises et quelle est la capacité de l’État et du secteur industriel à les combattre. Enfin, nous comparerons nos conclusions à celles tirées d’autres études sur le piratage dans l’industrie des jeux de hasard et nous discuterons de l’importance de nos conclusions pour les systèmes d’application de la loi, de sécurité et de protection des consommateurs.This paper studies the relationship between criminal organization and social control in the area of computer crime. We examine a “cheat at play” scheme that hacked into electronic gambling machines. We focus on how these cyber-attacks were committed and on the ability of the state and the industry to control them. We compare and contrast our findings with the research on hacking and the gambling industry and conclude by discussing the implications that our research has for law enforcement, security and public policy

No planet for HD 166435

The G0V star HD166435 has been observed by the fiber-fed spectrograph ELODIE as one of the targets in the large extra-solar planet survey that we are conducting at the Observatory of Haute-Provence. We detected coherent, low-amplitude, radial-velocity variations with a period of 3.7987days, suggesting a possible close-in planetary companion. Subsequently, we initiated a series of high-precision photometric observations to search for possible planetary transits and an additional series of CaII H and K observations to measure the level of surface magnetic activity and to look for possible rotational modulation. Surprisingly, we found the star to be photometrically variable and magnetically active. A detailed study of the phase stability of the radial-velocity signal revealed that the radial-velocity variability remains coherent only for durations of about 30days. Analysis of the time variation of the spectroscopic line profiles using line bisectors revealed a correlation between radial velocity and line-bisector orientation. All of these observations, along with a one-quarter cycle phase shift between the photometric and the radial-velocity variationss, are well explained by the presence of dark photospheric spots on HD166435. We conclude that the radial-velocity variations are not due to gravitational interaction with an orbiting planet but, instead, originate from line-profile changes stemming from star spots on the surface of the star. The quasi-coherence of the radial-velocity signal over more than two years, which allowed a fair fit with a binary model, makes the stability of this star unusual among other active stars. It suggests a stable magnetic field orientation where spots are always generated at about the same location on the surface of the star.Comment: 9 pages, 8 figures, Accepted for publication in A&