Sliderule-like property of Wigner's little groups and cyclic S-matrices for multilayer optics

It is noted that two-by-two S-matrices in multilayer optics can be represented by the Sp(2) group whose algebraic property is the same as the group of Lorentz transformations applicable to two space-like and one time-like dimensions. It is noted also that Wigner's little groups have a sliderule-like property which allows us to perform multiplications by additions. It is shown that these two mathematical properties lead to a cyclic representation of the S-matrix for multilayer optics, as in the case of ABCD matrices for laser cavities. It is therefore possible to write the N-layer S-matrix as a multiplication of the N single-layer S-matrices resulting in the same mathematical expression with one of the parameters multiplied by N. In addition, it is noted, as in the case of lens optics, multilayer optics can serve as an analogue computer for the contraction of Wigner's little groups for internal space-time symmetries of relativistic particles.Comment: RevTex 13 pages, Secs. IV and V revised and expande

Composite Fermions and the Fractional Quantum Hall Effect: Essential Role of the Pseudopotential

The mean field (MF) composite Fermion (CF) picture successfully predicts the band of low lying angular momentum multiplets of fractional quantum Hall systems for any value of the magnetic field. This success cannot be attributed to a cancellation between Coulomb and Chern--Simons interactions between fluctuations beyond the mean field. It results instead from the short range behavior of the Coulomb pseudopotential in the lowest Landau level (LL). The class of pseudopotentials for which the MFCF picture is successful can be defined, and used to explain the success or failure of the picture in different cases (e.g. excited LL's, charged magneto-excitons, and Laughlin quasiparticles in a CF hierarchy picture).Comment: 4 pages, 4 figures (RevTeX+epsf); talk at EP2DS-XII

LRR Focus: Labor Party Advocates

[Excerpt] For more than a decade, Tony Mazzocchi, Presidential Assistant of the Oil, Chemical and Atomic Workers Union, has traversed the nation as the principal organizer of the Labor Party Advocates. His message: For the past ten years, I have openly declared my belief that unless the trade union movement in this country seizes the political initiative and organizes a labor party, it will never again be the force it once was. Responding to this challenge, in October 1993, some 80 trade unionist\u27s from 23 states voted to convene a founding convention. Then, in the spring of this year, LPA\u27S interim steering committee endorsed a proposal to hold the convention in Denver in 1995

Adapting Dutch agriculture to climate change

This review starts with a brief discussion on agricultural land use in the Netherlands, followed by an overview of the expected climatic changes in the Netherlands and the consequences of land use change on current agricultural practices. Subsequently, adaptation strategies as suggested in the literature are summarized and discussed