Bargaining or Price Posting?

We study the endogenous determination of the trading mechanism in a search economy with a continuum of homogenous sellers and heterogeneous buyers.PRICING ; INFORMATION ; TRADE

W. M. Keck Observatory's next-generation adaptive optics facility

We report on the preliminary design of W.M. Keck Observatory's (WMKO's) next-generation adaptive optics (NGAO) facility. This facility is designed to address key science questions including understanding the formation and evolution of today's galaxies, measuring dark matter in our galaxy and beyond, testing the theory of general relativity in the Galactic Center, understanding the formation of planetary systems around nearby stars, and exploring the origins of our own solar system. The requirements derived from these science questions have resulted in NGAO being designed to have near diffraction-limited performance in the near-IR (K-Strehl ~ 80%) over narrow fields (< 30" diameter) with modest correction down to ~ 700 nm, high sky coverage, improved sensitivity and contrast and improved photometric and astrometric accuracy. The resultant key design features include multi-laser tomography to measure the wavefront and correct for the cone effect, open loop AO-corrected near-IR tip-tilt sensors with MEMS deformable mirrors (DMs) for high sky coverage, a high order MEMS DM for the correction of atmospheric and telescope static errors to support high Strehls and high contrast companion sensitivity, point spread function (PSF) calibration to benefit quantitative astronomy, a cooled science path to reduce thermal background, and a high-efficiency science instrument providing imaging and integral field spectroscopy

The infrared imaging spectrograph (IRIS) for TMT: spectrograph design

The Infra-Red Imaging Spectrograph (IRIS) is one of the three first light instruments for the Thirty Meter Telescope (TMT) and is the only one to directly sample the diffraction limit. The instrument consists of a parallel imager and off-axis Integral Field Spectrograph (IFS) for optimum use of the near infrared (0.84um-2.4um) Adaptive Optics corrected focal surface. We present an overview of the IRIS spectrograph that is designed to probe a range of scientific targets from the dynamics and morphology of high-z galaxies to studying the atmospheres and surfaces of solar system objects, the latter requiring a narrow field and high Strehl performance. The IRIS spectrograph is a hybrid system consisting of two state of the art IFS technologies providing four plate scales (4mas, 9mas, 25mas, 50mas spaxel sizes). We present the design of the unique hybrid system that combines the power of a lenslet spectrograph and image slicer spectrograph in a configuration where major hardware is shared. The result is a powerful yet economical solution to what would otherwise require two separate 30m-class instruments.Comment: 15 pages, 11 figure

To robotize chemistry laboratories. An example of organic synthesis: 2-Boc-amino-N-hydroxy-3-phenyl-propionamide

The paper describes the development of periodic modules used for the peptide synthesis of hydroxamic acid. A powder conveyor using the principle of positive weighing distribution is described. Purification is provided using automatic filtration and a liquid— liquid extraction module separation device. Device quality is improved using failure mode and effects analysis

Optimization of control parameters of a hot cold controller by means of Simplex type methods

This paper describes a hot/cold controller for regulating crystallization operations. The system was identified with a common method (the Broida method) and the parameters were obtained by the Ziegler-Nichols method. The paper shows that this empirical method will only allow a qualitative approach to regulation and that, in some instances, the parameters obtained are unreliable and therefore cannot be used to cancel variations between the set point and the actual values. Optimization methods were used to determine the regulation parameters and solve this identcation problem. It was found that the weighted centroid method was the best one

Dynamic multilateral markets

We study dynamic multilateral markets, in which players' payoffs result from intra-coalitional bargaining. The latter is modeled as the ultimatum game with exogenous (time-invariant) recognition probabilities and unanimity acceptance rule. Players in agreeing coalitions leave the market and are replaced by their replicas, which keeps the pool of market participants constant over time. In this infinite game, we establish payoff uniqueness of stationary equilibria and the emergence of endogenous cooperation structures when traders experience some degree of (heterogeneous) bargaining frictions. When we focus on market games with different player types, we derive, under mild conditions, an explicit formula for each type's equilibrium payoff as the market frictions vanish

Lyot-plane phase masks for improved high-contrast imaging with a vortex coronagraph

Context. The vortex coronagraph is an optical instrument that precisely removes on-axis starlight allowing for high contrast imaging at small angular separation from the star, a crucial capability for direct detection and characterization of exoplanets and circumstellar disks. Telescopes with aperture obstructions, such as secondary mirrors and spider support structures, require advanced coronagraph designs to provide adequate starlight suppression. Aims. We introduce a phase-only Lyot-plane optic to the vortex coronagraph, which offers improved contrast performance on telescopes with complicated apertures. Potential solutions for the European Extremely Large Telescope (E-ELT) are described. Methods. Adding a Lyot-plane phase mask relocates residual starlight away from a region of the image plane, thereby reducing stellar noise and improving sensitivity to off-axis companions. The phase mask is calculated using an iterative phase retrieval algorithm. Results. Numerically, we achieve a contrast on the order of 10-6 for a companion with angular displacement as small as 4λ/D with an E-ELT type aperture. Even in the presence of aberrations, improved performance is expected compared to either a conventional vortex coronagraph or an optimized pupil plane phase element alone

Facteurs de production et qualité sensorielle des fromages

Cette revue fait le point sur les connaissances acquises au cours des 10 dernières années sur les relations entre les facteurs de conduite des animaux (génétiques, physiologiques, alimentaires) et la qualité sensorielle des fromages. Chez la vache, avec des fabrications au lait entier, la race peut modifier les caractéristiques de texture des fromages. Cet effet est essentiellement lié aux différences de composition chimique des laits et donc de gras/sec des fromages. Au sein d'une même race, des différences importantes de texture et de goût ont été observées en fonction des variants génétiques de la caséine β (espèce bovine) et surtout αs1 (espèce caprine). Le stade physiologique n'a un effet marqué sur la couleur, la texture et le goût qu'en tout début ou en toute fin de lactation. En revanche, les mammites ont un effet négatif important sur les caractéristiques sensorielles des fromages. L'utilisation d'ensilage de maïs conduit toujours à des fromages plus blancs et parfois à des différences de flaveur. Lorsqu'elle est correctement réalisée, la conservation de l'herbe sous forme d'ensilage comparativement au foin ne modifie pas ou peu les caractéristiques sensorielles des fromages, en dehors de leur couleur, plus jaune avec l'ensilage. Par contre, d'importantes différences de caractéristiques sensorielles sont observées entre des fromages selon que le lait provient de vaches recevant une ration à base d'herbe conservée ou conduites au printemps, au pâturage. Plusieurs essais récents ont mis en évidence un effet de la composition botanique des fourrages ingérés par les vaches laitières sur la texture et la flaveur des fromages. Ces différents effets sont dus à la présence dans le lait de molécules ou de structures issues directement de l'alimentation (carotènes, terpènes) ou produites par l'animal (plasmine, acides gras, structure des micelles de la caséine) en raison de ses caractéristiques génétiques ou physiologiques ou sous l'effet d'une alimentation spécifique