Harmonic expansions and quasi-riemannian geometry in Kaluza-Klein theories

Since Kaluza-Klein supergravity does not contain the observed particles as elementary fields, alternative approaches in Kaluza-Klein theories without external gauge fields may be considered. We take up Weinberg's suggestion of changing the tangent space group and we find that some or all of the gauge field strengths associated with isometry group vanish unless there is torsion.     

RESEARCH NOTE: PHOTOREACTION OF 4', 5'-DIHYDROPSORALEN WITH THYMINE

Abstract— The photocycloaddition reaction of 4',5'-dihydropsoralen with thymine was carried out in solution and in the frozen state. A major photoadduct was isolated and characterized by elemental analysis and physical methods. The photoadduct was proven to be the 1:1 C₄-cycloaddition product, an analogue of furocoumarin-DNA biadduct, with the stereochemistry of anti -head-to-head formed through 2+2 addition reaction between the pyrone double bond of 4', 5'-dihydropsoralenand 5,6-double bond of thymine.     

Multichannel Mueller matrix ellipsometer for real-time spectroscopy of anisotropic surfaces and films

A multichannel ellipsometer in the dual-rotating-compensator configuration has been developed for potential applications in real-time Mueller matrix spectroscopy of anisotropic surfaces and films. This instrument provides spectra (1.7-5.3 eV) in all 16 elements of the unnormalized Mueller matrix M of a film-substrate system with a minimum overall data acquisition time of t(a) = 0.25 s. We have applied this instrument first for high-precision determination of spectra in M with t(a) = 2.5 s for a microscopically sculptured film.     

A bistatic Doppler technique to measure forward scattering at large angles of incidence

We present a bistatic Doppler method to measure forward scatter at large angles of incidence. The Doppler shifted signal avoids contamination by the direct signal between antennae. We illuminated a small area on a rotating table with a 95-GHz transmitter pointed at 60-80° angles of incidence. The area velocity was nearly constant. The scattering media was crushed rock with root mean square (rms) height to wavelength ratio near unity. Although theory precludes Doppler shift for targets moving in the plane of bistatic collinear antennae, shifts occurred at the monostatic backscattering value predicted by twice the table velocity within the illuminated area. The Rayleigh distributions of the Doppler shifted signal, with increasing standard deviation and corresponding decreasing peak amplitude as angle of incidence increased, are expected for the unity ratio, and so verify that Doppler shifted forward scatter was measured. The increased standard deviation with increasing angle is expected because of the increased sensitivity to smaller slope facets of the rock. The reference signal recorded for a metal plate signal also verifies the bistatic Doppler shift and precludes contamination by multiply-reflected backscatter. Minor modifications will allow grazing angle behaviour to be approached. It appears that further theory is needed to understand the bistatic Doppler process.