Alternative axiomatics and complexity of deliberative STIT theories

We propose two alternatives to Xu's axiomatization of the Chellas STIT. The first one also provides an alternative axiomatization of the deliberative STIT. The second one starts from the idea that the historic necessity operator can be defined as an abbreviation of operators of agency, and can thus be eliminated from the logic of the Chellas STIT. The second axiomatization also allows us to establish that the problem of deciding the satisfiability of a STIT formula without temporal operators is NP-complete in the single-agent case, and is NEXPTIME-complete in the multiagent case, both for the deliberative and the Chellas' STIT.Comment: Submitted to the Journal of Philosophical Logic; 13 pages excluding anne

Numerical Simulations to Evaluate and Compare the Performances of Existing and Novel Degrader Materials for Proton Therapy

The performance of the energy degrader in terms of beam properties directly impacts the design and cost of cyclotron-based proton therapy centers. The aim of this study is to evaluate the performances of different existing and novel degrader materials. The quantitative estimate is based on detailed GEANT4 simulations that analyze the beam-matter interaction and provide a determination of the beam emittance increase and transmission. Comparisons between existing (aluminum, graphite, beryllium) and novel (boron carbide and diamond) degrader materials are provided and evaluated against semi-analytical models of multiple Coulomb scattering. The results showing a potential in emittance reduction for novel materials are presented and discussed in detail.Comment: Submitted for IPAC 2018 "light peer review

Lockdown for All, Hardship for Some. Insights from the First Wave of the CoCo Project

How disruptive is Covid-19 to everyday life? How is the French population experiencing the lockdown? Is it magnifying existing inequalities and affecting social cohesion? The CoCo project sheds light on these pressing questions by comparing living conditions in France before and after the lockdown. This is the first of a series of research briefs that we will publish in the forthcoming weeks. We will explore this new experience of “sheltering-in-place” and its impact on family life, schooling, work, health and well-being. This brief explores how French society has coped with the first two weeks of the lockdown. We find that the virus has rapidly become a tangible threat, as more than forty percent of the population knows someone who has been infected. Despite this, three out of four persons say that they do not feel overly stressed out. In certain cases, the reaction has been almost philosophical -- long hours spent at home allow people to slow down and think about the meaning of life. More than anything else, it is having access to green spaces and nature which provides some relief to those attempting to cope with this home-based social organization. Still, some cracks have appeared. Women, foreign-born residents, and individuals facing financial hardship are subject to greater emotional strain than the rest of the population. Gender inequalities have been particularly reinforced during the lockdown: women have been spending even more time than usual cleaning and taking care of others. Although the Covid-19 virus tends to disproportionately strike men, the consequences of the lockdown more intenselyaffect women

Beyond Admissibility: Dominance Between Chains of Strategies

Admissible strategies, i.e. those that are not dominated by any other strategy, are a typical rationality notion in game theory. In many classes of games this is justified by results showing that any strategy is admissible or dominated by an admissible strategy. However, in games played on finite graphs with quantitative objectives (as used for reactive synthesis), this is not the case. We consider increasing chains of strategies instead to recover a satisfactory rationality notion based on dominance in such games. We start with some order-theoretic considerations establishing sufficient criteria for this to work. We then turn our attention to generalised safety/reachability games as a particular application. We propose the notion of maximal uniform chain as the desired dominance-based rationality concept in these games. Decidability of some fundamental questions about uniform chains is established

Life after lockdown: Getting back on track or charting a new course?

How disruptive is Covid-19 to everyday life? How is the French population experiencing the lockdown? Is it magnifying inequalities and affecting social cohesion? The CoCo project sheds lights on these pressing questions by comparing living conditions in France before, during, and after the lockdown. This is the fourth of a series of research briefs, which now cover the entire lockdown period Has life under the lockdown been a parenthesis or is it the new normal? Beyond whether or not people began to resume their usual activities on 11 May, the consequences of the lockdown experience on people’s attitudes and opinions are the core of this policy brief. Did the lockdown trigger new sociopolitical orientations? Or did it instead accelerate ongoing trends

The Salish Sea Ecosystem in FishBase and SeaLifeBase

This contribution will review the biodiversity of the Salish Sea and its regional components, the Puget Sound and Georgia Strait based on the incorporation into major database, i.e., FishBase (www.fishbase.org) for fish and SeaLifeBase (www.sealifebase.org) for other marine organisms, of a massive body of literature data. Because it incorporated in this massive databases, this information is also vetted for quality and can be compared with information from similar ecosystems. Over 238 fish species are documented for the Salish Sea (152 for Puget Sound, 193 for the Georgia Strait) in FishBase, and over 1600 species of non-fish vertebrates and invertebrates in SeaLifeBase, from a body of over 1800 published references. Though this documentation effort is ongoing, we can now say that overall, the Salish Sea is as biodiverse as can be expected of a temperate ecosystem of its size, i.e., 18,000 square km. This biodiversity has declined, however, and the causes for which are briefly discussed

Ambient dose simulation of the ProtherWal proton therapy centre radioactive shielding decay using BDSIM and FISPACT-II

Next-generation proton therapy centres couple treatment and research programs, leading to higher beam currents and longer irradiation times than in clinical conditions. Large fluxes of energetic secondary particles are produced and long- and short-term radioactive nuclides are generated in the concrete shielding of the cyclotron vault. While the overall long-term activation of the centre is well known from the shielding design activation studies, the short-term activation peaks are still of importance when radiation protection studies are involved. The centre shielding design was validated using the BDSIM/FISPACT-II methodology combining particle tracking and Monte Carlo particle-matter interactions simulations using Beam Delivery Simulation (BDSIM) and the computation of the activation using FISPACT-II. We establish, as the next stage of our methodology, the simulation of the decay radiation of the activated concrete shielding and the accurate scoring of the related radiation protection quantities. A single BDSIM simulation per radioactive nuclide is performed based on the nuclide concentration obtained from the prior FISPACT-II activation computations at the start of a given cooling period. The evolution of the radiation protection quantities is obtained by scaling the results with the nuclides activity obtained at later times from fast FISPACT-II computations. We show the evolution of the ambient dose equivalent in the centre vault when considering regular concrete and Low Activation Concrete (LAC) as shielding material to demonstrate the efficiency of LAC mix in mitigating the shielding activation