Homo Sapiens Sapiens Meets Homo Strategicus at the Laboratory

Homo Strategicus populates the vast plains of Game Theory. He knows all logical implications of his knowledge (logical omniscience) and chooses optimal strategies given his knowledge and beliefs (rationality). This paper investigates the extent to which the logical capabilities of Homo Sapiens Sapiens resemble those possessed by Homo Strategicus. Controlling for other-regarding preferences and beliefs about the rationality of others, we show, in the laboratory, that the ability of Homo Sapiens Sapiens to perform complex chains of iterative reasoning is much better than previously thought. Subjects were able to perform about two to three iterations of reasoning on average.iterative reasoning; depth of reasoning; logical omniscience; rationality; experiments; other-regarding preferences

Cognitive abilities and behavior in strategic-form games.*

This paper investigates the relation between cognitive abilities and behavior in strategic-form games with the help of a novel experiment. The design allows us first to measure the cognitive abilities of subjects without confound and then to evaluate their impact on behaviour in strategic-from games. We find that subjects with better cognitive abilities show more sophisticated behavior and make better use of information on cognitive abilities and preferences of opponents. Although we do not find evidence for Nash behavior, observed behaviour is remarkably sophisticated, as almost 80% of subjects behave near optimal and outperform Nash behavior with respect to expected pay-offs.cognitive ability; behaviours; strategic-form games; experiments; preferences; sophistication

CONTRACTING OVER PERSISTENT INFORMATION

We consider a dynamic principal-agent problem, where the sole instrument the principal has to incentivize the agent is the disclosure of information. The principal aims at maximizing the (discounted) number of times the agent chooses the principal’s preferred action. We show that there exists an optimal policy, where the principal recommends its most preferred action and discloses information as a reward in the next period, until either this action becomes statically optimal for the agent or the agent perfectly learns the state

Investigating Ramp Wave Propagation inside Silica Glass with Laser Experiments and Molecular Simulations

Under elastic shock compression silica glass exhibits a very specific behaviour. A shock propagating inside a material is usually seen as the propagation of a discontinuity. However in silica glass, shocks are unstable and lead to the propagation of a ramp wave where the shock front becomes gradually larger over time. Ramp waves were already reported in the literature, however their origin remain uncertain. This work presents an original study combining laser shock-induced experiments and molecular dynamics simulation aiming to improve the understanding of the mechanisms involved. Experimental ramp waves were directly observed using shadowgraphy technique allowing for an estimation of the head and tail velocities. Molecular dynamics simulations were carried out in order to reproduce ramp waves and to gain insight into the material properties. Ramp waves were observed for both elastic and plastic shockwaves. In the latter case, the plastic waves were preceded by an elastic ramp precursor. The sound speed, related to the material compressibility, was found to decrease with increasing pressure, as observed experimentally for quasi-static hydrostatic loading, thus providing an explanation for the instabilities that lead to the propagation of ramp waves

Contrasting transcriptional programs control postharvest development of apples (Malus x domestica Borkh.) submitted to cold storage and ethylene blockage.

Apple is commercially important worldwide. Favorable genomic contexts and postharvest technologies allow year-round availability. Although ripening is considered a unidirectional developmental process toward senescence, storage at low temperatures, alone or in combination with ethylene blockage, is effective in preserving apple properties. Quality traits and genome wide expression were integrated to investigate the mechanisms underlying postharvest changes. Development and conservation techniques were responsible for transcriptional reprogramming and distinct programs associated with quality traits. A large portion of the differentially regulated genes constitutes a program involved in ripening and senescence, whereas a smaller module consists of genes associated with reestablishment and maintenance of juvenile traits after harvest. Ethylene inhibition was associated with a reversal of ripening by transcriptional induction of anabolic pathways. Our results demonstrate that the blockage of ethylene perception and signaling leads to upregulation of genes in anabolic pathways. We also associated complex phenotypes to subsets of differentially regulated genes. KEYWORDS: 1-methylcyclopropene, firmness, fruit quality, gene expression, microarra

Mouthiers-sur-Boëme, Chez les Rois

Chez les Rois est un gisement de référence de l'Aurignacien charentais et un des rares gisements aurignaciens européens à avoir livré des restes humains en place. Fouillé entre 1930 et 1939 par Potut et entre 1948 et 1952 par Mouton et Joffroy (1958), ce gisement a fait l'objet d'un sondage en 2005 et d'une fouille programmée entre 2006 et 2008 (d'Errico et Vanhaeren 2005, 2006, 2007, 2008). Cette opération de terrain a fait suite à la reprise de l'étude des restes humains et du matériel archéologique issus des fouilles Mouton et Joffroy ainsi qu'à sa datation (Ramirez Rozzi et al. sous presse). L'objectif des nouvelles fouilles était de préciser l'attribution culturelle des assemblages, la chronologie et nature de l'occupation aurignacienne ainsi que l'affiliation taxinomique des groupes humains qui ont fréquenté le site

A coumaroyl-ester-3-hydroxylase insertion mutant reveals the existence of nonredundant meta-hydroxylation pathways and essential roles for phenolic precursors in cell expansion and plant growth

Cytochromes P450 monooxygenases from the CYP98 family catalyze the meta-hydroxylation step in the phenylpropanoid biosynthetic pathway. The ref8 Arabidopsis (Arabidopsis thaliana) mutant, with a point mutation in the CYP98A3 gene, was previously described to show developmental defects, changes in lignin composition, and lack of soluble sinapoyl esters. We isolated a T-DNA insertion mutant in CYP98A3 and show that this mutation leads to a more drastic inhibition of plant development and inhibition of cell growth. Similar to the ref8 mutant, the insertion mutant has reduced lignin content, with stem lignin essentially made of p-hydroxyphenyl units and trace amounts of guaiacyl and syringyl units. However, its roots display an ectopic lignification and a substantial proportion of guaiacyl and syringyl units, suggesting the occurrence of an alternative CYP98A3-independent meta-hydroxylation mechanism active mainly in the roots. Relative to the control, mutant plantlets produce very low amounts of sinapoyl esters, but accumulate flavonol glycosides. Reduced cell growth seems correlated with alterations in the abundance of cell wall polysaccharides, in particular decrease in crystalline cellulose, and profound modifications in gene expression and homeostasis reminiscent of a stress response. CYP98A3 thus constitutes a critical bottleneck in the phenylpropanoid pathway and in the synthesis of compounds controlling plant development. CYP98A3 cosuppressed lines show a gradation of developmental defects and changes in lignin content (40% reduction) and structure (prominent frequency of p-hydroxyphenyl units), but content in foliar sinapoyl esters is similar to the control. The purple coloration of their leaves is correlated to the accumulation of sinapoylated anthocyanins

The human OPA1delTTAG mutation induces premature age-related systemic neurodegeneration in mouse

Dominant optic atrophy is a rare inherited optic nerve degeneration caused by mutations in the mitochondrial fusion gene OPA1. Recently, the clinical spectrum of dominant optic atrophy has been extended to frequent syndromic forms, exhibiting various degrees of neurological and muscle impairments frequently found in mitochondrial diseases. Although characterized by a specific loss of retinal ganglion cells, the pathophysiology of dominant optic atrophy is still poorly understood. We generated an Opa1 mouse model carrying the recurrent Opa1(delTTAG) mutation, which is found in 30% of all patients with dominant optic atrophy. We show that this mouse displays a multi-systemic poly-degenerative phenotype, with a presentation associating signs of visual failure, deafness, encephalomyopathy, peripheral neuropathy, ataxia and cardiomyopathy. Moreover, we found premature age-related axonal and myelin degenerations, increased autophagy and mitophagy and mitochondrial supercomplex instability preceding degeneration and cell death. Thus, these results support the concept that Opa1 protects against neuronal degeneration and opens new perspectives for the exploration and the treatment of mitochondrial diseases