The role of players’ identification in the population on the trusting and the trustworthy behavior an experimental investigation

We study to what extent identification does matter for trustfulness and trustworthiness to emerge in a population of players. Our experimen- tal protocol is designed for isolating the effects of trustees’ identification. Trustees’ identification is a necessary condition for introducing a reputation mechanism. We run three treatments. In each treatment groups 6 players interact repeatedly and randomly and play a 30 periods investment game (Berg & al. 1995). In the first treatment players can’t identify each other, in the second one players can identify each other as trustee and in the third one players identify each other both as trustee and trustor. We show that, according to the expectation, trustees’ identification has a positive effect on reciprocity. However it doesn’t affect the average trust in the population. Trust is significantly higher than in the complete anonymous treatment only when players identify each other in both roles. We show that this enhance of trust is the result of mutual trust-reciprocity relationships formation.

When Allais meets Ulysses: Dynamic Consistency and the Certainty Effect

We report experimental findings about subjects’ behavior in dynamic decision problems involving multistage lotteries with different timings of resolution of uncertainty. Our within subject design allows us to study violations of the independence axiom in the light of the dynamic axioms' ones : dynamic consistency, consequentialism and reduction of compound lotteries.

Coupling Linear Sloshing with Six Degrees of Freedom Rigid Body Dynamics

Fluid motion in tanks is usually described in space industry with the so-called Lomen hypothesis which assumes the vorticity is null in the moving frame. We establish in this contribution that this hypothesis is valid only for uniform rotational motions. We give a more general formulation of this coupling problem, with a compact formulation. We consider the mechanical modeling of a rigid body with a motion of small amplitude, containing an incompressible fluid in the linearized regime. We first establish that the fluid motion remains irrotational in a Galilean referential if it is true at the initial time. When continuity of normal velocity and pressure are prescribed on the free surface, we establish that the global coupled problem conserves an energy functional composed by three terms. We introduce the Stokes - Zhukovsky vector fields, solving Neumann problems for the Laplace operator in the fluid in order to represent the rotational rigid motion with irrotational vector fields. Then we have a good framework to consider the coupled problem between the fluid and the rigid motion. The coupling between the free surface and the ad hoc component of the velocity potential introduces a "Neumann to Dirichlet" operator that allows to write the coupled system in a very compact form. The final expression of a Lagrangian for the coupled system is derived and the Euler-Lagrange equations of the coupled motion are presented.Comment: 23 page

Optimization incentive and relative riskiness in experimental coordination games

We compare the experimental results of three stag-hunt games. In contrast to Battalio et al. (2001), our design keeps the riskiness ratio of the payoff-dominant and the risk-dominant strategies at a constant level as the optimisation premium is increased. We define the riskiness ratio as the relative payoff range of the two strategies. We find that decreasing the riskiness ratio while keeping the optimization premium constant increases sharply the frequency of the risk-dominant strategy. On the other hand an increase of the optimization premium with a constant riskiness ratio has no effect on the choice frequencies. Finally, we confirm the dynamic properties found by Battalio et al. that increasing the optimization premium favours best-response and sensitivity to the history of play.

Risk and Inequality Aversion in Social Dilemmas

We experimentally investigate cooperative behavior in a social dilemma situation, where the socially efficient outcome may be encouraged by risk aversion and/or inequality aversion. The first part of our experiment is devoted to the elicitation of subjects' aversion profile, taking care to not confuse the two dimensions. Subjects are then grouped by three according to their aversion profiles, and interact in a repeated social dilemma game. In this game, agents are characterised by a social status so that higher the agent's status, higher will be her earnings. Cooperation is costly for a majority of agents at each period, but statuses can be reversed in future periods. We show that cooperation is strongly in°uenced by the group's aversion profile. Groups averse in both dimensions cooperate more than groups averse in only one dimension. Moreover cooperation seems to be more affected by risk aversion, whereas one might interpret cooperative behavior as an inequality averse or altruistic attitude.

Risque relatif et sélection d'équilibre dans un jeu de coordination : une analyse expérimentale

We compare the experimental results of three stag-hunt games. In contrast to Battalio et al.(2001), our design keeps the relative riskiness of the two strategies at a constant level as the optimisation premium is increased. Furthermore, we also test the effect of a decrease of the relative riskiness of the two strategies, when the optimization premium remains constant. Our results show that in the latter case, the frequency of the risk-dominant strategy increases sharply, while in the former case the frequency of the risk-dominant strategy is unaffected. However, we confirm the earlier findings of Battalio et al. that an increase of the optimisation premium, all things equal, favours best response and sensitivity to the payoff-history.coordination, sélection d’équilibre, expériences

Contrasting effects of information sharing on common-pool resource extraction behavior: Experimental findings

This paper experimentally investigates the impact of different information sharing mechanisms in a common-pool resource game, with a view to finding a mechanism that is both efficient and inexpensive for the managing agency. More precisely, we compare the observed extraction levels produced as a result of three mechanisms: a mandatory information sharing mechanism and two voluntary information sharing mechanisms that differ in the degree of freedom given to the players. Our main result is that a voluntary information sharing mechanism could help in reaching a lower average extraction level than that observed with the mandatory mechanism

Relaxation of phonons in the Lieb-Liniger gas by dynamical refermionization

We investigate the Lieb-Liniger gas initially prepared in an out-of-equilibrium state that is Gaussian in terms of the phonons. Because the phonons are not exact eigenstates of the Hamiltonian, the gas relaxes to a stationary state at very long times. Thanks to integrability, that stationary state needs not be a thermal state. We characterize the stationary state of the gas after relaxation and compute its phonon population distribution. Technically, this follows from the mapping between the exact eigenstates of the Lieb-Liniger Hamiltonian and those of a non-interacting Fermi gas -- a mapping provided by the Bethe equations -- , as well as on bosonization formulas valid in the low-energy sector of the Hilbert space. We apply our results to the case where the initial state is an excited coherent state for a single phonon mode, and we compare them to exact results obtained in the hard-core limit.Comment: Main text : 6 pages, 1 figures, Supplemental Material : 2 pages, 1 figur

Prototyping coronagraphs for exoplanet characterization with SPHERE

The detection and characterization of extrasolar planets with SPHERE (Spectro Polarimetric High contrast Exoplanet REsearch) is challenging and in particular relies on the ability of a coronagraph to attenuate the diffracted starlight. SPHERE includes 3 instruments, 2 of which can be operated simultaneously in the near IR from 0.95 to 1.8 microns. This requirements is extremely critical for coronagraphy. This paper briefly introduces the concepts of 2 coronagraphs, the Half-Wave Plate Four Quadrant Phase Masks and the Apodized Pupil Lyot Coronagraph, prototyped within the SPHERE consortium by LESIA (Observatory of Paris) and FIZEAU (University of Nice) respectively. Then, we present the measurements of contrast and sensitivity analysis. The comparison with technical specifications allows to validate the technology for manufacturing these coronagraphs.Comment: 10 pages, will be published in the proceeding of the SPIE conference Volume 7015 "Adaptive Optics", held in Marseille from 23 to 28 june 200

Low level of Fibrillarin, a ribosome biogenesis factor, is a new independent marker of poor outcome in breast cancer

International audienceBackground: A current critical need remains in the identification of prognostic and predictive markers in early breast cancer. It appears that a distinctive trait of cancer cells is their addiction to hyperactivation of ribosome biogenesis. Thus, ribosome biogenesis might be an innovative source of biomarkers that remains to be evaluated. Methods: Here, fibrillarin (FBL) was used as a surrogate marker of ribosome biogenesis due to its essential role in the early steps of ribosome biogenesis and its association with poor prognosis in breast cancer when overexpressed. Using 3,275 non-metastatic primary breast tumors, we analysed FBL mRNA expression levels and protein nucleolar organisation. Usage of TCGA dataset allowed transcriptomic comparison between the different FBL expression levelsrelated breast tumours. Results: We unexpectedly discovered that in addition to breast tumours expressing high level of FBL, about 10% of the breast tumors express low level of FBL. A correlation between low FBL mRNA level and lack of FBL detection at protein level using immunohistochemistry was observed. Interestingly, multivariate analyses revealed that these low FBL tumors displayed poor outcome compared to current clinical gold standards. Transcriptomic data revealed that FBL expression is proportionally associated with distinct amount of ribosomes, low FBL level being associated with low amount of ribosomes. Moreover, the molecular programs supported by low and high FBL expressing tumors were distinct. Conclusion: Altogether, we identified FBL as a powerful ribosome biogenesis-related independent marker of breast cancer outcome. Surprisingly we unveil a dual association of the ribosome biogenesis FBL factor with prognosis. These data suggest that hyper-but also hypo-activation of ribosome biogenesis are molecular traits of distinct tumors