Comment on "Finite size scaling in Neural Networks"

We use a binary search tree and the simplex algorithm to measure the fraction of patterns that can be stored by an Ising perceptron. The algorithm is much faster than exhaustive search and allows us to obtain accurate statistics up to a system size of N=42. The results show that the finite size scaling ansatz Nadler and Fink suggest in [1] cannot be applied to estimate accurately the storage capacity from small systems. [1] W.Nadler and W.Fink: Phys.Rev.Lett. 78, 555 (1997)Comment: LaTeX with 1 postscript figure, using REVTe

Heterogeneity in Exchange Rate Expectations: Evidence on the Chartist-Fundamentalist Approach

This paper examines heterogeneity in exchange rate expectations. Whereas agents’ heterogeneity is key in modern exchange rate models, evidence on determinants of heterogeneity is weak so far. Our sample, covering expectations from about 300 forecasters over 15 years, shows remarkable time variation in dispersion. Determinants of dispersion are consistent with the chartist-fundamentalist approach: misalignments of the exchange rate and exchange rate changes explain heterogeneity. The risk premium influences heterogeneity as well, but possible impacts from macroeconomic variables and exchange rate’s volatility are dominated by the other determinants.exchange rate, heterogeneity, dispersion, chartists, fundamentalists

DENIS Observations of Multibeam Galaxies in the Zone of Avoidance

Roughly 25% of the optical extragalactic sky is obscured by the dust and stars of our Milky Way. Dynamically important structures might still lie hidden in this zone. Various surveys are presently being employed to uncover the galaxy distribution in the Zone of Avoidance (ZOA) but all suffer from (different) limitations and selection effects. We illustrate the promise of using a multi-wavelength approach for extragalactic large-scale studies behind the ZOA, i.e. a combination of three surveys -- optical, systematic blind HI and near-infrared (NIR), which will allow the mapping of the peculiar velocity field in the ZOA through the NIR Tully-Fisher relation. In particular, we present here the results of cross-identifying HI-detected galaxies with the DENIS NIR survey, and the use of NIR colours to determine foreground extinctions.Comment: Accepted for publication in PASA. Proceedings of workshop "HI in the Local Universe, II", held in Melbourne, Sept. 1998. 9 pages, LaTeX2e, 2 encapsulated PS figures, 3 JPEG figures, Full resolution figures 2, 3 and 4 and full resolution paper are at ftp://ftp.iap.fr/pub/from_users/gam/PAPERS/HICONF

Four-Loop Decoupling Relations for the Strong Coupling

We compute the matching relation for the strong coupling constant within the framework of QCD up to four-loop order. This allows a consistent five-loop running (once the $\beta$ function is available to this order) taking into account threshold effects. As a side product we obtain the effective coupling of a Higgs boson to gluons with five-loop accuracy.Comment: 11 page

Quark mass thresholds in QCD thermodynamics

We discuss radiative corrections to how quark mass thresholds are crossed, as a function of the temperature, in basic thermodynamic observables such as the pressure, the energy and entropy densities, and the heat capacity of high temperature QCD. The indication from leading order that the charm quark plays a visible role at surprisingly low temperatures, is confirmed. We also sketch a way to obtain phenomenological estimates relevant for generic expansion rate computations at temperatures between the QCD and electroweak scales, pointing out where improvements over the current knowledge are particularly welcome.Comment: 14 pages. v2: minor additions and clarifications; published versio