A Note on Walrasian Equilibria with Moral Hazard and Aggregate Uncertainty

In a fundamental contribution, Prescott and Townsend (1984) [PT] have shown that the existence and efficiency properties of Walrasian equilibria extend to economies with moral hazard, when agents' trades are observable (exclusive contracts can be implemented). More recently, Bennardo and Chiappori (2003) [BC] have argued that Walrasian equilibria may (robustly) fail to exist when the class of moral hazard economies considered by Prescott and Townsend is generalized to allow for the presence of aggregate, in addition to idiosyncratic, uncertainty and for preferences which are nonseparable in consumption and effort. We re-examine here the existence and efficiency properties of Walrasian equilibria in the moral hazard economy considered by Bennardo and Chiappori. We show that Walrasian equilibria always exist in such economy and are incentive efficient, so the results of Prescott and Townsend continue to hold in the more general set-up considered by Bennardo and Chiappori

Competitive Equilibria with Asymmetric Information: Existence with Entry Fees.

This paper studies competitive equilibria in economies characterized by the presence of asymmetric information, where non-exclusive contracts with payoffs dependent on the agents' private information are traded on competitive markets. For such economies competitive equilibria may not exist with linear prices. We show that (non-trivial) competitive equilibria exist, under general conditions, with two part tariffs, i.e. if the cost of trading each contract consists of an entry fee and a linear component in the quantity traded.GENERAL EQUILIBRIUM ; ASYMMETRIC INFORMATION ; COMPETITION

A Note on the Convergence to Competitive Equilibria in Economies with Moral Hazard

asymmetric information; exclusivity; convergence

On the Sensitivity of a Hollow Sphere as a Multi-modal Resonant Gravitational Wave Detector

We present a numerical analysis to simulate the response of a spherical resonant gravitational wave detector and to compute its sensitivity. Under the assump- tion of optimal filtering, we work out the sensitivity curve for a sphere first taking into account only a single transducer, and then using a coherent analysis of the whole set of transducers.Comment: 24 pages, 11 figures, published versio

REINVENTANDO Cotidianos de Pesquisa

RESUMO Objetiva acompanhar e problematizar movimentos de composição de modos de pesquisar, realizados por mestrandos e doutorandos dos programas de Pós-Graduação da Universidade Federal do Espírito Santo (UFES), durante os anos de 2008 e 2009. Busca acompanhar os movimentos de produção de formas de pesquisar que são acionados nos fazeres cotidianos e que se produzem em meio aos encontros de corpos que desassossegam o pesquisador e o forçam a pensar e a criar. Em eio a esses movimentos de criação e desmanchamento de formas e de sentidos para aquilo que se passa com o pesquisador e o perpassa na duração das pesquisas considera ser importante e necessário avaliar os modos de compor que fazemos funcionar. Conclui que é com essa valiação que se problematiza o próprio fazer e que se segue apostando numa contínua criação de outros modos, mais potentes e afirmativos da vida

Effects of exciton deconfinement on the transient photoluminescence from thermally activated delayed fluorescence host-guest systems

For thermally activated delayed fluorescence (TADF) host-guest systems used in organic light-emitting diodes, understanding of the transient photoluminescence (PL) measurements is crucial for accurate determination of the photophysical rates of the emitter. Here, we study how the PL is affected by triplet-exciton deconfinement from the guest to the host molecules. This deconfinement can complicate the analysis of the PL decay and potentially lead to a loss of efficiency. From an analytical model, we find that the transient PL intensity remains bi-exponential in the presence of exciton deconfinement for the case of fast triplet diffusion, albeit with a longer decay time of the delayed component. Deconfinement might, therefore, not always be recognizable from a single transient PL measurement. The role of deconfinement depends on the energetic disorder, the guest concentration, and the energy difference Δ E T between triplet-exciton energies on the host and guest molecules and is effectively suppressed for Δ E T &gt; - &gt; 0.2 eV. We find from analytical modeling and kinetic Monte Carlo simulations that the decay can become non-bi-exponential and even show a distinct third decay step. The shape of the decay curves depends on the characteristic times for guest-host transfer and host diffusion, relative to the prompt and delayed decay times of the TADF emitter. A comparison with available experimental data is included, finding qualitative agreement with dedicated deconfinement studies and indicating the influence of other processes for the often observed power-law decay at long time scales. </p

Proximity effect model for x-ray transition edge sensors

Transition Edge Sensors are ultra-sensitive superconducting detectors with applications in many areas of research, including astrophysics. The device consists of a superconducting thin film, often with additional normal metal features, held close to its transition temperature and connected to two superconducting leads of a higher transition temperature. There is currently no way to reliably assess the performance of a particular device geometry or material composition without making and testing the device. We have developed a proximity effect model based on the Usadel equations to predict the effects of device geometry and material composition on sensor performance. The model is successful in reproducing I-V curves for two devices currently under study. We use the model to suggest the optimal size and geometry for TESs, considering how small the devices can be made before their performance is compromised. In the future, device modelling prior to manufacture will reduce the need for time-consuming and expensive testing.This work was partly supported by ESA CTP contract with No. 4000114932/15/NL/BW and EU H2020 AHEAD program

Intrinsic defects and their influence on the chemical and optical properties of TiO2x films

International audienceIn this work, TiO2 films produced by rf sputtering of a TiO2 target in argon and argon–oxygen plasmas were studied. The oxygen content in the feed gas was varied in a range 3–20%. The chemical composition and structure of films were characterized by Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy (XPS) and x-ray diffraction. Important information about the intrinsic defects of the films and their effects on the optical properties as well as a scheme of the energy band structure of the films could be derived from a combined use of optical spectroscopy and XPS