Revised Huang-Yang multipolar pseudopotential

A number of authors have recently pointed out inconsistencies of results obtained with the Huang-Yang multipolar pseudo-potential for low-energy scattering [K. Huang and K. C. Yang, Phys. Rev. A, v 105, 767 (1957); later revised in K. Huang, ``Statistical Mechanics'', (Wiley, New York, 1963)]. The conceptual validity of their original derivation has been questioned. Here I show that these inconsistencies are rather due to an {\em algebraic} mistake made by Huang and Yang. With the corrected error, I present the revised version of the multipolar pseudo-potential

How do you make a time series sing like a choir? Using the Hilbert-Huang transform to extract embedded frequencies from economic or financial time series

The Hilbert-Huang transform (HHT) was developed late last century but has still to be introduced to the vast majority of economists. The HHT transform is a way of extracting the frequency mode features of cycles embedded in any time series using an adaptive data method that can be applied without making any assumptions about stationarity or linear data-generating properties. This paper introduces economists to the two constituent parts of the HHT transform, namely empirical mode decomposition (EMD) and Hilbert spectral analysis. Illustrative applications using HHT are also made to two financial and three economic time series.business cycles; growth cycles; Hilbert-Huang transform (HHT); empirical mode decomposition (EMD); economic time series; non-stationarity; spectral analysis

Banking Panics and the Origin of Central Banking

Gorton and Huang (2001) argue that private coalitions of banks can act as central banks, issuing private money and providing deposit insurance during times of panic. This lender-of-last-resort role depends upon banking panics occurring threat of liquidation makes the private bank coalition incentive compatible, inducing banks to monitor each other. But, despite the evolution of private bank coalitions, government central banks and government deposit insurance schemes historically replaced the private bank coalitions. In this paper we ask why this transition from private arrangements to public arrangements occurred. We survey the historical and international evidence on panics, suggesting that Gorton and Huang (2001) are consistent with the evidence. Then, we extend Gorton and Huang (2001) to show the welfare improvement brought about by a government central bank replacing private bank coalitions as lender-of-last-resort. In particular, panics, while necessary for private coalitions to function, are costly because they disrupt the use of bank deposits as a medium of exchange. With government deposit insurance, panics do not occur, but the government must monitor banks. Such monitoring by the government is not as effective as private bank coalitions. We provide conditions under which the government can avoid the costs associated with panics by implementing deposit insurance and thereby raise social welfare.

Nucleon Structure Functions at Moderate Q**2: Relativistic Constituent Quarks and Spectator Mass Spectrum

We present a model description of the nucleon valence structure function applicable over the entire region of the Bjorken variable x, and above moderate values of Q**2 (> 1 GeV**2). We stress the importance of describing the complete spectrum of intermediate states which are spectator to the deep-inelastic collision. At a scale of 1 GeV**2 the relevant degrees of freedom are constituent quarks and pions. The large-x region is then described in terms of scattering from constituent quarks in the nucleon, while the dressing of constituent quarks by pions plays an important role at intermediate x values. The correct small-x behavior, which is necessary for the proper normalization of the valence distributions, is guaranteed by modeling the asymptotic spectator mass spectrum according to Regge phenomenology.Comment: 44 pages RevTeX, 9 uuencoded figures, accepted for publication in Nucl. Phys.

A composite open resonator for compact X-ray source

The results of calculation of the finesse of a composite open resonator for compact X-ray source are presented. The region of the resonator parameters has been found where the finesse is changed unessentially.Comment: 2 pages, LaTe