Contribution of simulation and gaming to natural resource management issues: An introduction

Nowadays, computer-mediated simulations and games are widely used in the field of natural resource management (NRM). They have proved to be useful for various purposes such as supporting decisionmaking processes and training. First, the specificities of the NRM research field are highlighted. Then, based on the analysis of the articles presented in this special issue of Simulation & Gaming, some key features related to the implementation of gaming in such a context are introduced. Finally, after reviewing the benefits of using simulation games in NRM, the authors stress the ethical issue of changing social relationships among stakeholders by playing a game with some of themGESTION DE L'ENVIRONNEMENT;RESSOURCE NATURELLE;SIMULATION;SOCIOLOGIE;JEU DE ROLE;BENEFITS;CONTEXT;COLLECTIVE POLICY DESIGN;DECISION MAKING;ETHICAL ISSUES;IMPLEMENTATION;NATURAL RESOURCE MANAGEMENT (NRM);SIMULATION GAMES;SOCIAL EMPOWERMENT;SOCIAL RELATIONSHIPS;SOCIOECOLOGICAL SYSTEMS;STAKEHOLDERS

Hybrid Meson Decay Phenomenology

The phenomenology of a newly developed model of hybrid meson decay is developed. The decay mechanism is based on the heavy quark expansion of QCD and the strong coupling flux tube picture of nonperturbative glue. A comprehensive list of partial decay widths of a wide variety of light, $s\bar s$, $c\bar c$, and $b \bar b$ hybrid mesons is presented. Results which appear approximately universal are highlighted along with those which distinguish different hybrid decay models. Finally, we examine several interesting hybrid candidates in detail.Comment: 37 pages, 2 figures, 6 tables, Revte

Probing Interstellar Dust with Infrared Echoes from the Cas A Supernova

We present the analysis of an IRS 5-38 {\mu}m spectrum and MIPS photometric measurements of an infrared echo near the Cassiopeia A supernova remnant observed with the Spitzer Space Telescope. We have modeled the recorded echo accounting for PAHs, quantum-heated carbon and silicate grains, as well as thermal carbon and silicate particles. Using the fact that optical light echo spectroscopy has established that Cas A originated from a type IIb supernova explosion showing an optical spectrum remarkably similar to the prototypical type IIb SN 1993J, we use the latter to construct template data input for our simulations. We are then able to reproduce the recorded infrared echo spectrum by combining the emission of dust heated by the UV burst produced at the shock breakout after the core-collapse and dust heated by optical light emitted near the visual maximum of the supernova light curve, where the UV burst and optical light curve characteristics are based on SN 1993J. We find a mean density of \sim680 H cm^{-3} for the echo region, with a size of a few light years across. We also find evidence of dust processing in the form of a lack of small PAHs with less than \sim300 carbon atoms, consistent with a scenario of PAHs destruction by the UV burst via photodissociation at the estimated distance of the echo region from Cas A. Furthermore, our simulations suggest that the weak 11 {\mu}m features of our recorded infrared echo spectrum are consistent with a strong dehydrogenated state of the PAHs. This exploratory study highlights the potential of investigating dust processing in the interstellar medium through infrared echoes.Comment: 16 pages, 14 figures, accepted for publication in the Astrophysical Journa

The XMM large scale structure survey: optical vs. X-ray classifications of active galactic nuclei and the unified scheme

Our goal is to characterize AGN populations by comparing their X-ray and optical classifications. We present a sample of 99 spectroscopically identified X-ray point sources in the XMM-LSS survey which are significantly detected in the [2-10] keV band, and with more than 80 counts. We performed an X-ray spectral analysis for all of these 99 X-ray sources. Introducing the fourfold point correlation coefficient, we find only a mild correlation between the X-ray and the optical classifications, as up to 30% of the sources have differing X-ray and optical classifications: on one hand, 10% of the type 1 sources present broad emission lines in their optical spectra and strong absorption in the X-rays. These objects are highly luminous AGN lying at high redshift and thus dilution effects are totally ruled out, their discrepant nature being an intrinsic property. Their X-ray luminosities and redshifts distributions are consistent with those of the unabsorbed X-ray sources with broad emission lines. On the other hand, 25/32 are moderate luminosity AGN, which are both unabsorbed in the X-rays and only present narrow emission lines in their optical spectra. The majority of them have an optical spectrum which is representative of the host galaxy. We finally infer that dilution of the AGN by the host galaxy seems to account for their nature. 5/25 have been defined as Seyfert 2. In conclusion, most of these 32 discrepant cases can be accounted for by the standard AGN unified scheme, as its predictions are not met for only 12% of the 99 X-ray sources. ABRIDGEDComment: 25 pages, 19 figures, Accepted for publication in A&

Experimental investigation of boundary layer instabilities and transition on sharp and blunt cones in Oxford’s High-Density Tunnel

Boundary layer instabilities and transition to turbulence on a 7-degree half-angle cone with varying nose-tip radii in Mach 6 and 7 flow are investigated using a combination of surface heat transfer measurements, surface pressure measurements, and high speed schlieren images. The experiments are performed at unit-Reynolds numbers ranging from [22-44]*10^6/m in University of Oxford’s High-Density Tunnel (HDT). The transition Reynolds number, Re_{X_T}, increases with increasing nose tip Reynolds number, Re_{R_N}, for Re_{R_N}<10^5. In this range, evidence of second-mode wave instabilities are observed in both schlieren images and surface pressure measurements. For 10^5 < Re_{R_N} < 4*10^5, Re_{X_T} remains constant and coherent streaks above the boundary layer are observed with schlieren imaging. Images of the interaction of these features with a boundary layer breaking down to a fully turbulent state are presented. The freestream disturbance environment is also varied through existence of several steady state plateaus created by the natural operation of the facility, and characterised with multi-point focused laser differential interferometry (FLDI). Re_{X_T} increases by 10-60% with increasing plateau number which is independent of Re_{R_N}. Variation in freestream fluctuation amplitude with frequency and Reynolds number are in agreement with previous studies while variation with plateau is not. The discrepancy is explained by receptivity functions which are sensitive to the inclination angle of disturbances. A method for measuring the inclination angle using correlated FLDI signals is presented and reveals a consistent trend with plateau number. The trend is physically explained by changes in the relative contribution of entropic and acoustic modes with time