3,551 research outputs found

    Dynamics of adaptive agents with asymmetric information

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    We apply path-integral techniques to study the dynamics of agent-based models with asymmetric information structures. In particular, we devise a batch version of a model proposed originally by Berg et al. [Quant. Fin. 1 (2001) 203], and convert the coupled multi-agent processes into an effective-agent problem from which the dynamical order parameters in ergodic regimes can be derived self-consistently together with the corresponding phase structure. Our dynamical study complements and extends the available static theory. Results are confirmed by numerical simulations.Comment: minor revision of text, accepted by JSTA

    Optimal Choice and Beliefs with Ex Ante Savoring and Ex Post Disappointment

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    We propose a new decision criterion under risk in which people extract both utility from anticipatory feelings ex ante and disutility from disappointment ex post. The decision maker chooses his degree of optimism, given that more optimism raises both the utility of ex ante feelings and the risk of disappointment ex post. We characterize the optimal beliefs and the preferences under risk generated by this mental process and apply this criterion to a simple portfolio choice/insurance problem. We show that these preferences are compatible with first-degree and second-degree stochastic dominance, are consistent with the preference reversal in the Allais paradox, and predict that the decision maker takes on less risk compared to an expected utility maximizer. This speaks to the equity premium puzzle and to the preference for low deductibles in insurance contracts

    Gender Identity and Womens' Supply of Labor and Non-Market Work: Panel Data Evidence for Germany

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    This paper aims to verify results of the innovative study on gender identity for the USA by Bertrand et al. (2015) for Germany. They found that women who would earn more than their husbands distort their labor market outcome in order not to violate traditional gender identity norms. Using data from the German Socio-economic Panel Study (SOEP) we also find that the distribution of the share of income earned by the wife exhibits a sharp drop to the right of the half, where the wife's income exceeds the husband's income. The results of the fixed effects regression confirm that gender identity has an impact on the labor supply of full time working women, but only in Western Germany. We also show that gender identity affects the supply of housework but in contrast to the US where women increase their contribution to non-market work when they actually have a higher income than their husbands, we find for Germany that women only barely reduce their weekly hours of non-market work once their income exceeds that of their husbands

    Experimental study of Pomeron

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    A Pomeron phenomenon remains a mystery. A short review of the experimental situation in diffractive physics and an account of some spectacular manifestations of the Pomeron are given.Comment: 17 pages, 7 Figs, LATEX. Talk given at the conference "From the smallest to largest distances", ITEP, Moscow, 24-26 May 2001. Changes: Fig.2 replace

    Locating very high energy gamma ray sources with arc minute accuracy

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    The angular accuracy of gamma-ray detectors is intrinsically limited by the physical processes involved in photon detection. Although a number of point-like sources were detected by the COS-B satellite, only two were unambiguously identified by time signature with counterparts at longer wavelengths. By taking advantage of the extended longitudinal structure of Very High Energy gamma-ray showers, measurements in the TeV energy range can pinpoint source coordinates to arc minute accuracy. This was demonstrated using Cerenkov air shower imaging techniques. With two telescopes in coincidence, the individual event circular probable error will be 0.13 deg. The half-cone angle of the field of view is effectively 1 deg

    The role of uncertainty, sentiment and cross-country interactions in G7 output dynamics

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    Output fluctuations in the G7 are characterised using a VAR model of countries' actual and expected outputs and uncertainty over these. New measures are developed to quantify the relative importance of economic prospects-versus-uncertainty, global-versus-national effects and fundamentals-versus-sentiment for countries' persistent output movements. National and global contributions are found to be equally important across the G7 although considerable differences exist between countries. Uncertainty, and especially cross-country uncertainty, is important in propagating the effects of shocks and generates around 20% of countries' persistent output movements on average. Fundamentals dominate output movements although, with an 80:20 split, sentiment plays a non-negligible role

    The Host Galaxy of GRB 990123

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    We present deep images of the field of gamma-ray burst (GRB) 990123 obtained in a broad-band UV/visible bandpass with the Hubble Space Telescope, and deep near-infrared images obtained with the Keck-I 10-m telescope. Both the HST and Keck images show that the optical transient (OT) is clearly offset by 0.6 arcsec from an extended object, presumably the host galaxy. This galaxy is the most likely source of the metallic-line absorption at z = 1.6004 seen in the spectrum of the OT. With magnitudes V_{C} ~ 24.6 +/- 0.2 and K = 21.65 +/- 0.30 mag this corresponds to an L ~ 0.7 L_* galaxy, assuming that it is located at z = 1.6. The estimated unobscured star formation rate is SFR ~ 6 M_sun/yr, which is not unusually high for normal galaxies at comparable redshifts. The strength of the observed metallic absorption lines is suggestive of a relatively high metallicity of the gas, and thus of a chemically evolved system which may be associated with a massive galaxy. It is also indicative of a high column density of the gas, typical of damped Ly-alpha systems at high redshifts. We conclude that this is the host galaxy of GRB 990123. No other obvious galaxies are detected within the same projected radius from the OT. There is thus no evidence for strong gravitational lensing magnification of this burst, and some alternative explanation for its remarkable energetics may be required. The observed offset of the OT from the center of its apparent host galaxy, 5.5 +/- 0.9 proper kpc (projected) in the galaxy's rest-frame, both refutes the possibility that GRBs are related to galactic nuclear activity and supports models of GRBs which involve the death and/or merger of massive stars. Further, the HST image suggests an intimate connection of GRB 990123 and a star-forming region.Comment: Updated references. 12 pages including 3 Postscript figures. Camera- ready reproductions of the figures can be found at http://astro.caltech.edu/~jsb/GRB/grb990123.htm

    Continuous optical monitoring during the prompt emission of GRB 060111B

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    We present the time-resolved optical emission of GRB 060111B during its prompt phase, measured with the TAROT robotic observatory. This is the first time that the optical emission from a gamma-ray burst has been continuously monitored with a temporal resolution of a few seconds during the prompt gamma-ray phase. The temporal evolution of the prompt optical emission at the level of several seconds is used to provide a clue to the origin of this emission. The optical emission was found to decay steadily from our first measure, 28s after the trigger, in contrast to the gamma-ray emission, which exhibits strong variability at the same time. This behaviour strongly suggests that the optical emission is due to the reverse shock
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