On the robustness of concealing cost information in oligopoly

Competing firms are usually better informed about their own cost parameters than about those of their rivals. Therefore, it is an important issue to study the incentives of firms to exchange private cost information. We resolve and further generalize an influential model of Raith (1996) and show that, independent of the number of firms, concealing cost information is a dominant firm strategy in heterogeneous Bertrand oligopolies with substitutive as well as with complementary goods.cost uncertainty

No information sharing in oligopoly : the case of price competition with cost uncertainty

We show that concealing cost information is a dominant strategy in heterogeneous Bertrand oligopolies. This result enables us to endogenize the number of firms in a market in terms of market size, entry costs, and unit cost uncertainty.In diesem Beitrag zeigen wir, daß für ein heterogenes Oligopol die dominante Strategie der Unternehmen bei Preiswettbewerb lautet, keine Informationen über die Höhe der Produktionsstückkosten auszutauschen. Auf der Basis dieses Ergebnisses läßt sich die Anzahl der Unternehmen im Markt in Abhängigkeit vom Marktvolumen, von den Kosten des Marktzutritts und von der Unsicherheit über die Höhe der Produktionsstückkosten endogenisieren

Electrode effects on the observability of destructive quantum interference in single-molecule junctions

Destructive quantum interference (QI) has been a source of interest as a new paradigm for molecular electronics as the electronic conductance is widely dependent on the occurrence or absence of destructive QI effects. In order to interpret experimentally observed transmission features, it is necessary to understand the effects of all components of the junction on electron transport. We perform non-equilibrium Green's function calculations within the framework of density functional theory to assess the structure-function relationship of transport through pyrene molecular junctions with distinct QI properties. The chemical nature of the anchor groups and the electrodes controls the Fermi level alignment, which determines the observability of destructive QI. A thorough analysis allows to disentangle the transmission features arising from the molecule and the electrodes. Interestingly, graphene electrodes introduce features in the low-bias regime, which can either mask or be misinterpreted as QI effects, while instead originating from the topological properties of the edges. Thus, this first principles analysis provides clear indications to guide the interpretation of experimental studies, which cannot be obtained from simple H\"uckel model calculations.Comment: 12 pages, 8 figure

Wettbewerb bei unvollständiger Information: Informationsaustausch oder stillschweigende Kollusion?

Der Beitrag sollte verdeutlichen, dass sich seit den Pioniermodellen mit unvollständiger Information mittlerweile eine recht heterogene Klasse von Ansätzen etabliert hat, die sich unter alternativen Grundannahmen mit der Frage auseinandersetzen, ob Unternehmen angesichts diverser Unsicherheiten auf ihren Märkten einen Anreiz besitzen, ihre privaten Informationen mit Konkurrenten zu teilen (Informationsaustausch) oder diese für sich zu behalten (stillschweigende Kollusion). Auf der Basis der bestehenden Literatur demonstrierte der vorliegende Beitrag ausgehend von einem Referenzmodell mit vollständiger Information die einfachst mögliche Modellierung unvollständiger Kosten- und Nachfrageinformation, mit der sich die Frage des Informationsaustausches zwischen Unternehmen in oligopolistischen Marktstrukturen modelltheoretisch erfassen lässt. Er liefert eine einleuchtende Erklärung für das immer wieder festzustellende Phänomen, dass die Unternehmen einer Branche zwar ihre jeweiligen Informationen über die Nachfragesituation bereitwillig den Konkurrenten zur Verfügung stellen, jedoch keinerlei Informationen über die verwendete Produktionstechnologie preisgeben. Die optimale Informationspolitik eines erfolgreichen Unternehmens obliegt folglich der Kunst zu wissen, worüber man spricht und worüber man besser schweigt

Landscape statistics of the low autocorrelated binary string problem

The statistical properties of the energy landscape of the low autocorrelated binary string problem (LABSP) are studied numerically and compared with those of several classic disordered models. Using two global measures of landscape structure which have been introduced in the Simulated Annealing literature, namely, depth and difficulty, we find that the landscape of LABSP, except perhaps for a very large degeneracy of the local minima energies, is qualitatively similar to some well-known landscapes such as that of the mean-field 2-spin glass model. Furthermore, we consider a mean-field approximation to the pure model proposed by Bouchaud and Mezard (1994, J. Physique I France 4 1109) and show both analytically and numerically that it describes extremely well the statistical properties of LABSP

SuperConga: an open-source framework for mesoscopic superconductivity

We present SuperConga, an open-source framework for simulating equilibrium properties of unconventional and ballistic singlet superconductors, confined to two-dimensional (2D) mesoscopic grains in a perpendicular external magnetic field, at arbitrary low temperature. It aims at being both fast and easy to use, enabling research without access to a computer cluster, and visualization in real-time with OpenGL. The core is written in C++ and CUDA, exploiting the embarrassingly parallel nature of the quasiclassical theory of superconductivity by utilizing the parallel computational power of modern GPUs. The framework self-consistently computes both the superconducting order-parameter and the induced vector potential, and finds the current density, free energy, induced flux density, local density of states, as well as the magnetic moment. A user-friendly Python frontend is provided, enabling simulation parameters to be defined via intuitive configuration files, or via the command-line interface, without requiring a deep understanding of implementation details. For example, complicated geometries can be created with relative ease. The framework ships with simple tools for analyzing and visualizing the results, including an interactive plotter for spectroscopy. An overview of the theory is presented, as well as examples showcasing the framework's capabilities and ease of use. The framework is free to download from https://gitlab.com/superconga/superconga, which also links to the extensive user manual, containing even more examples, tutorials and guides.Comment: Accepted version. Review-style article, 31 pages and link to software at https://gitlab.com/superconga/supercong

First experimental results of very high accuracy centroiding measurements for the neat astrometric mission

NEAT is an astrometric mission proposed to ESA with the objectives of detecting Earth-like exoplanets in the habitable zone of nearby solar-type stars. NEAT requires the capability to measure stellar centroids at the precision of 5e-6 pixel. Current state-of-the-art methods for centroid estimation have reached a precision of about 2e-5 pixel at two times Nyquist sampling, this was shown at the JPL by the VESTA experiment. A metrology system was used to calibrate intra and inter pixel quantum efficiency variations in order to correct pixelation errors. The European part of the NEAT consortium is building a testbed in vacuum in order to achieve 5e-6 pixel precision for the centroid estimation. The goal is to provide a proof of concept for the precision requirement of the NEAT spacecraft. In this paper we present the metrology and the pseudo stellar sources sub-systems, we present a performance model and an error budget of the experiment and we report the present status of the demonstration. Finally we also present our first results: the experiment had its first light in July 2013 and a first set of data was taken in air. The analysis of this first set of data showed that we can already measure the pixel positions with an accuracy of about 1e-4 pixel.Comment: SPIE conference proceeding

A detector interferometric calibration experiment for high precision astrometry

Context: Exoplanet science has made staggering progress in the last two decades, due to the relentless exploration of new detection methods and refinement of existing ones. Yet astrometry offers a unique and untapped potential of discovery of habitable-zone low-mass planets around all the solar-like stars of the solar neighborhood. To fulfill this goal, astrometry must be paired with high precision calibration of the detector. Aims: We present a way to calibrate a detector for high accuracy astrometry. An experimental testbed combining an astrometric simulator and an interferometric calibration system is used to validate both the hardware needed for the calibration and the signal processing methods. The objective is an accuracy of 5e-6 pixel on the location of a Nyquist sampled polychromatic point spread function. Methods: The interferometric calibration system produced modulated Young fringes on the detector. The Young fringes were parametrized as products of time and space dependent functions, based on various pixel parameters. The minimization of func- tion parameters was done iteratively, until convergence was obtained, revealing the pixel information needed for the calibration of astrometric measurements. Results: The calibration system yielded the pixel positions to an accuracy estimated at 4e-4 pixel. After including the pixel position information, an astrometric accuracy of 6e-5 pixel was obtained, for a PSF motion over more than five pixels. In the static mode (small jitter motion of less than 1e-3 pixel), a photon noise limited precision of 3e-5 pixel was reached