Random Numbers and Gaming

In Counter Strike: Global Offensive spray pattern control becomes a muscle memory to a player after long periods of playing. It’s a design choice that makes the gunplay between players more about instant crosshair placement with the faster player usually winning. This is very different from the gunplay of the current popular shooter Player Unknown’s Battlegrounds. Player Unknown’s Battleground’s spray pattern for the guns are random. So how does this affect the player experience? Well as opposed to Counter Strike: Global Offensive, the design choice makes gunplay between two players more about how a person can adapt faster when encountering another. So why does the change from a set pattern to random make for such a different experience in gameplay. Did the usage of randomness make for such a different experience? Random numbers in video games are utilized frequently and have been used for a long time, whether it was better for the player experience is often hard to tell. So just what is this “randomness”? What games use random numbers and why? Are random numbers a bad practice? The usage of random numbers in games is nothing new, but poor implementations and bad business practices have given random numbers a smudge mark on their reputation

Some CoRoT highlights - A grip on stellar physics and beyond

About 2 years ago, back in 2009, the first CoRoT Symposium was the occasion to present and discuss unprecedented data revealing the behaviour of stars at the micromagnitude level. Since then, the observations have been going on, the target sample has enriched and the work of analysis of these data keeps producing first rank results. These analyses are providing the material to address open questions of stellar structure and evolution and to test the so many physical processes at work in stars. Based on this material, an increasing number of interpretation studies is being published, addressing various key aspects: the extension of mixed cores, the structure of near surface convective zones, magnetic activity, mass loss, ... Definitive conclusions will require cross-comparison of results on a larger ground (still being built), but it is already possible at the time of this Second CoRoT Symposium, to show how the various existing results take place in a general framework and contribute to complete our initial scientific objectives. A few results already reveal the potential interest in considering stars and planets globally, as it is stressed in several talks at this symposium. It is also appealing to consider the fast progress in the domain of Red Giants and see how they illustrate the promising potential of space photometry beyond the field of stellar physics, in connex fields like Galactic dynamics and evolution.Comment: 9 pages, 13 figures, to appear in Proceedings of the Second CoRoT Symposium, held in Marseille, June 14-17th 201

Cold/sticky systems

The understanding of complex and/or large vacuum systems operating at cryogenic temperatures requires a specific knowledge of vacuum science at such temperatures. At room temperature, molecules with a low binding energy to a surface are not pumped. However, at cryogenic temperatures, their sojourn time is significantly increased, thanks to the temperature reduction, which allows a ‘cryopumping’. This pumping mechanism is described by different regimes. Sticking probabilities, capture factor and thermal transpiration concepts are also used to characterize the pumping mechanism. At cryogenic temperature, a gas load into a vacuum system turns into an increase of the surface coverage and of its associated vapour pressure. Some adsorption isotherms of H2 and He which differ with key parameters such as surface nature and temperature are also presented. As an application of this field of vacuum technology, the vacuum system of the CERN Large Hadron Collider is introduced. The implementation of cryosorbers and the consequences of He leaks in the accelerator beam tube are reported

Measurement of the primary phodesorption yield at 4.2 K, 77 K and room temperature in a quasi-closed geometry

In the context of the Large Hadron Collider project, the normal incidence photodesorption yield of neutral gases from a stainless steel surface has been measured at 4.2 K, 77 K and room temperature. The yields were measured using a synchrotron radiation photon beam with a critical energy of 45.3 eV, which is very near that to be expected in the LHC. It has been shown that the primary photodesorption yield decrease with decreasing temperature. The gases desorbed were H2, CH4, CO and CO2. At 4.2 K and 77 K the H2O primary photodesorption yield was practically zero. At room temperature the primary photodesorption yields were 5 10-4, 1.6 10-5, 2.5 10-4 and 2.2 10-4 molecules photon-1 respectively for H2, CH4, CO and CO2. At 77 K the primary photodesorption yields of H2, CH4, CO and CO2 were reduced by factors of 2, 4, 17 and 32 respectively with respect to room temperature. At 4.2 K, these corresponding reduction factors were 14, 20, 42 and 31

Comparative seismology of pre- and main sequence stars in the instability strip

Pulsational properties of 1.8 M$_{\odot}$ stellar models covering the latest stages of contraction toward the main sequence up to early hydrogen burning phases are investigated by means of linear nonadiabatic analyses. Results confirm that pre-main sequence stars (pms) which cross the classical instability strip on their way toward the main sequence are pulsationally unstable with respect to the classical opacity mechanisms. For both pms and main sequence types of models in the lower part of the instability strip, the unstable frequency range is found to be roughly the same. Some non-radial unstable modes are very sensitive to the deep internal structure of the star. It is shown that discrimination between pms and main sequence stages is possible using differences in their oscillation frequency distributions in the low frequency range.Comment: 8 pages, 9 figures, accepted for publication in A&

Eclipsing Binary Stars from Space

We have begun a programme to obtain high-precision photometry of bright detached eclipsing binary (dEB) stars with the Wide field InfraRed Explorer (WIRE) satellite. Due to the small aperture of WIRE only stars brighter than V=6 can be observed. We are collecting data for about a dozen dEB targets and here we present preliminary results for three of them. We have chosen dEBs with primary components of B and early A type. One of our aims is to combine the information from the light curve analyses of the eclipses with asteroseismic information from the analysis of the pulsation of the primary component.Comment: 4 pages, 3 figures. To appear in conference proceedings for IAU Symposium No. 240: Binary Stars as Critical Tools & Tests in Contemporary Astrophysics, eds. W. Hartkopf, E. Guinan & P. Harmane

The Search for the QGP: A Critical Appraisal

Over the past 15 years, an extensive program of high energy nuclear collisions at BNL and CERN has been devoted to the experimental search for the quark-gluon plasma predicted by QCD. The start of RHIC this year will increase the highest available collision energy by a factor 10. This seems a good time for a critical assessment: what have we learned so far and what can we hope to learn in the coming years?Comment: 20 pages, 20 figure