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Gaia Data Release 2. Summary of the contents and survey properties
No full textInternational audienceContext. We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources brighter than magnitude 21. In addition epoch astrometry and photometry are provided for a modest sample of minor planets in the solar system. Aims: A summary of the contents of Gaia DR2 is presented, accompanied by a discussion on the differences with respect to Gaia DR1 and an overview of the main limitations which are still present in the survey. Recommendations are made on the responsible use of Gaia DR2 results. Methods: The raw data collected with the Gaia instruments during the first 22 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into this second data release, which represents a major advance with respect to Gaia DR1 in terms of completeness, performance, and richness of the data products. Results: Gaia DR2 contains celestial positions and the apparent brightness in G for approximately 1.7 billion sources. For 1.3 billion of those sources, parallaxes and proper motions are in addition available. The sample of sources for which variability information is provided is expanded to 0.5 million stars. This data release contains four new elements: broad-band colour information in the form of the apparent brightness in the GBP (330-680 nm) and GRP (630-1050 nm) bands is available for 1.4 billion sources; median radial velocities for some 7 million sources are presented; for between 77 and 161 million sources estimates are provided of the stellar effective temperature, extinction, reddening, and radius and luminosity; and for a pre-selected list of 14 000 minor planets in the solar system epoch astrometry and photometry are presented. Finally, Gaia DR2 also represents a new materialisation of the celestial reference frame in the optical, the Gaia-CRF2, which is the first optical reference frame based solely on extragalactic sources. There are notable changes in the photometric system and the catalogue source list with respect to Gaia DR1, and we stress the need to consider the two data releases as independent. Conclusions: Gaia DR2 represents a major achievement for the Gaia mission, delivering on the long standing promise to provide parallaxes and proper motions for over 1 billion stars, and representing a first step in the availability of complementary radial velocity and source astrophysical information for a sample of stars in the Gaia survey which covers a very substantial fraction of the volume of our galaxy
Demand for Information, Macroeconomic Uncertainty, and the Response of U.S. Treasury Securities to News
No full textWe measure demand for information prior to nonfarm payroll announcements using a novel dataset consisting of clicks on news articles. We find that when information demand is high shortly before the release of the nonfarm payroll announcement, the price response of U.S. Treasury note futures to nonfarm payroll news surprises doubles. We argue that this relationship stems from the fact that market participants have more incentive to collect information when uncertainty about asset payoffs is higher, as implied by Bayesian learning models. Thus, high information demand about macroeconomic news is a proxy for high macroeconomic uncertainty
VizieR Online Data Catalog: 46 open clusters GaiaDR2 HR diagrams (Gaia Collaboration, 2018)
No full textVizieR On-line Data Catalog: J/A+A/616/A10. Originally published in: 2018A&A...616A..10GWe have determined the membership of 46 open clusters. For the nine clusters within 250pc we determined optimised parallaxes based on the combined information extracted from the measured parallax and proper motion values. These clusters are : in Tables A1a & A3: alphaPer, Blanco1, ComaBer, Hyades, IC2391, IC2602, NGC2451A, Pleiades, Praesepe. The remaining 37 clusters are in Table A1b & A4: Coll140, IC4651, IC4665, IC4725, IC4756, NGC0188, NGC0752, NGC0869, NGC0884, NGC1039, NGC1901, NGC2158, NGC2168, NGC2232, NGC2323, NGC2360, NGC2422, NGC2423, NGC2437, NGC2447, NGC2516, NGC2547, NGC2548, NGC2682, NGC3228, NGC3532, NGC6025, NGC6281, NGC6405, NGC6475, NGC6633, NGC6774, NGC6793, NGC7092, Stock2, Trump02, Trump10. (4 data files)
Information-Theoretic Limits of Strategic Communication
No full textIn this article, we investigate strategic information transmission over a noisy channel. This problem has been widely investigated in Economics, when the communication channel is perfect. Unlike in Information Theory, both encoder and decoder have distinct objectives and choose their encoding and decoding strategies accordingly. This approach radically differs from the conventional Communication paradigm, which assumes transmitters are of two types: either they have a common goal, or they act as opponent, e.g. jammer, eavesdropper. We formulate a point-to-point source-channel coding problem with state information, in which the encoder and the decoder choose their respective encoding and decoding strategies in order to maximize their long-run utility functions. This strategic coding problem is at the interplay between Wyner-Ziv's scenario and the Bayesian persuasion game of Kamenica-Gentzkow. We characterize a single-letter solution and we relate it to the previous results by using the concavification method. This confirms the benefit of sending encoded data bits even if the decoding process is not supervised, e.g. when the decoder is an autonomous device. Our solution has two interesting features: it might be optimal not to use all channel resources; the informational content impacts the encoding process, since utility functions capture preferences on source symbols
Interactive Information Design
No full textWe study the interaction between multiple information designers who try to influence the behavior of a set of agents. When the set of messages available to each designer is finite, such games always admit subgame perfect equilibria. When designers produce public information about independent pieces of information, every equilibrium of the direct game (in which the set of messages coincides with the set of states) is an equilibrium with larger (possibly infinite) message sets. The converse is true for a class of Markovian equilibria only. When designers produce information for their own corporation of agents, pure strategy equilibria exist and are characterized via an auxiliary normal form game. In an infinite-horizon multi-period extension of information design games, a feasible outcome which Pareto dominates a more informative equilibrium of the one-period game is supported by an equilibrium of the multi-period game
On Deciding When to Decide
No full textWe consider a decision maker who follows a status quo without reconsidering her implicit decision at every period. Only as a result of certain events will she ask herself whether she would like to change her choice. We ask when this mode of decision making is compatible with optimality. We state conditions on the set of databases that would make the decision maker take an explicit decision, which are equivalent to the following representation: the decision maker entertains a set of theories, of which one is that her current choice is the best; she is inert as long as that theory beats any alternative theory according to a maximum likelihood criterion
Essais en finance d'entreprise empirique
No full textThis thesis is divided into three chapters. The first one deals with Central Clearing Counterparties (CCPs) and their resiliency in crisis times. This is a joint work with François Derrien, Evren Ors and David Thesmar. Focusing on CCPs backed repo trades during the eurozone crisis, we show that the market factored in the default of CCPs. In turn, this affected their capacity to ensure liquidity in the interbank market. Our results have strong consequences for the way CCPs should be regulate. The second chapter aims at quantifying the impact of the rise of the concentration in the banking sector on aggregate credit fluctuations. Building on novel empirical approach, I show that big players’ idiosyncratic shocks have a limited impact on aggregate credit. The explanation lies in the fact that the strength of banking groups idiosyncratic shocks is limited compared to aggregate and subsidiaries level ones. The last chapter, a joint work with Thomas Bourveau and Adrien Matray, focuses on the transmission of corporate risk culture. We show that subsidiaries of the same banking group tend to assess future risks in similar ways. In turn, this gives insights on how banking crisis can spread be fueled by corporate risk culture.Cette thèse réalisée au sein du département finance d’HEC Paris est constituée de trois parties. La première s’intéresse à la résilience des chambres de compensation en temps de crise. C’est un travail réalisé avec François Derrien, Evren Örs et David Thesmar dans lequel nous montrons que le manque de régulation de ces acteurs conduit à une détérioration de la confiance qui leur est accordée quand les conditions macroéconomiques se détériorent. Ceci impacte alors négativement leur capacité à assurer une liquidité suffisante sur le marché interbancaire. Le deuxième chapitre porte sur l’impact de la concentration du secteur bancaire autour de quelques grands groupes sur l’allocation macroéconomique du crédit. J’y développe une approche innovante pour répondre à cette question et montre que cet impact est limité: les chocs idiosyncratiques des "big players" n’ont qu’un rôle limité dans la fluctuation du crédit aggrégé. La dernière partie est un travail réalisé avec Adrien Matray et Thomas Bourveau. Nous nous intéressons à la transmission de la culture du risque au sein du secteur bancaire et montrons que les filiales d’un groupe bancaire tendent à converger quant à leur évaluation du risque futur. En retour, cela peut amener à une sous-évaluation de ce dernier et impacter la stabilité financière
Do Investors Pay Sufficient Attention to Banks’ Unrealized Gains and Losses on Available-for-Sale Securities?
No full textUnrealized gains and losses on available-for-sale securities (AFSGL) are included in Other Comprehensive Income (OCI) and directly affect shareholders’ equity but are not included in earnings. We investigate whether unrealized AFSGL help predict future earnings and whether analysts and investors incorporate the information conveyed by unrealized AFSGL in a timely manner. We conduct our investigation on a sample of banks because unrealized AFSGL are material in the banking industry. First, we show that unrealized AFSGL are material and help in predicting next period realized AFSGL and future earnings change. Second, we document that financial analysts are slow to react to unrealized AFSGL and update their forecasts after AFSGL are realized in earnings. Third, we find that investors are also slow to react to unrealized AFSGL and do so only after AFSGL is included (realized) in earnings and after financial analysts update their forecasts. We document an annual difference of 5% in future abnormal returns between banks in the top and bottom quintiles of past unrealized AFSGL. A zero-cost trading strategy that relies on public information about unrealized AFSGL generates a sizeable monthly alpha that ranges between 1.8% and 1.9%
Enhancing Perceived Safety in Human–Robot Collaborative Construction Using Immersive Virtual Environments
No full textAdvances in robotics now permit humans to work collaboratively with robots. However, humans often feel unsafe working alongside robots. Our knowledge of how to help humans overcome this issue is limited by two challenges. One, it is difficult, expensive and time-consuming to prototype robots and set up various work situations needed to conduct studies in this area. Two, we lack strong theoretical models to predict and explain perceived safety and its influence on human–robot work collaboration (HRWC). To address these issues, we introduce the Robot Acceptance Safety Model (RASM) and employ immersive virtual environments (IVEs) to examine perceived safety of working on tasks alongside a robot. Results from a between-subjects experiment done in an IVE show that separation of work areas between robots and humans increases perceived safety by promoting team identification and trust in the robot. In addition, the more participants felt it was safe to work with the robot, the more willing they were to work alongside the robot in the future
