Dynamic Surface Tension Behavior of a Mixed Insoluble/Soluble Surfactant Dispersion at Pulsating Air/Liquid Interfaces: Roles of the Soluble Surfactant

The influence of tyloxapol on the dynamic surface tension response of dipalmitoyl phosphatidylcholine (DPPC) dispersions at pulsating air/liquid interfaces was investigated. For a 1000 ppm DPPC dispersion prepared by sonication with a larger particle size, the dynamic surface activity of DPPC was strongly affected by the addition of 100 ppm tyloxapol. With a longer sonication time or smaller particle size, the DPPC inactivation was still observed but was somewhat less significant, resulting in slightly lower dynamic surface tensions. If a DPPC dispersion was sonicated in the presence of tyloxapol, the particle size of DPPC was greatly reduced by tyloxapol and the inhibitory effect of tyloxapol on the dynamic adsorption of DPPC may be significantly diminished. The results suggest that the competitive adsorption of tyloxapol may have a detrimental effect on the dynamic surface tension lowering ability of a DPPC dispersion with the extent depending on the DPPC dispersion state. Nevertheless, the dynamic surface activity of DPPC may be enhanced through the improved dispersion by tyloxapol if an appropriate preparation protocol is applied, and the inhibitory effect of tyloxapol may be reduced or overcome. Copyright 2001 Academic Press.     

The class number one problem for some non-abelian normal CM-fields of degree 48

We prove that there is precisely one normal CM-field of degree 48 with class number one which has a normal CM-subfield of degree 16: the narrow Hilbert class field of with .

     

Multimode resonances in square-shaped optical microcavities

Square-shaped two-dimensional optical microcavities (micro-cavities) were investigated for possible applications as filters for dense wavelength-division multiplexing. Multimode cavity resonances were observed in the elastic scattering of approximately 200-microm square-shaped micro-cavities in fused silica. Based on a two-dimensional k-space representation, we accounted for the multimode spectrum by different normal modes with rays confined by total internal reflection. The cavity-mode trajectories need not be closed after each round trip. Single-mode spectra are expected from smaller square-shaped micro-cavities.     

Optical processing of light-induced autofluorescence for characterization of tissue pathology

We describe an optical processing method for characterizing tissue pathology that is based on principal-component analysis of light-induced autofluorescence. A set of optical spectral filters, which are related to the principal-component loading vectors, is designed to process the autofluorescence signal optically and to generate principal-component scores from the autofluorescence spectra. The scores are then correlated with the tissue pathology. An optical processing system is designed that uses the in vivo fluorescence spectra recorded from nasopharyngeal tissues. We demonstrate that the system can differentiate nasopharyngeal carcinoma from normal tissue with a high degree of sensitivity and specificity and that the optical filters used in the system can be manufactured.     

Anomalous dispersion behavior of multiple-wave X-ray diffraction at absorption edges: determination of phase change at resonance

The effects of anomalous dispersion (resonance) on multiple reflection of x rays and their interference in crystals at atomic absorption edges are studied. Intensity ratios of two inversion-symmetry-related multiple diffractions at or near absorption edges exhibit highly phase-sensitive profiles with strong asymmetric characteristics, unlike those far from the edges. A new resonance perturbation Bethe approach is developed to explain this behavior. This leads to direct determination of the phase change for x-ray reflections at resonance.     

Baryon rapidity loss in relativistic Au + Au collisions

An excitation function of proton rapidity distributions for different centralities is reported from AGS Experiment E917 for Au+Au collisions at 6, 8, and 10.8 GeV/nucleon. The rapidity distributions from peripheral collisions have a valley at midrapidity which smoothly change to distributions that display a broad peak at midrapidity for central collisions. The mean rapidity loss increases with increasing beam energy, whereas the fraction of protons consistent with isotropic emission from a stationary source at midrapidity decreases with increasing beam energy. The data suggest that the stopping is substantially less than complete at these energies.     

Correlation between quantized electronic states and oscillatory thickness relaxations of 2D Pb islands on Si(111)-(7 x 7) surfaces

Two-dimensional lead (Pb) islands of varying heights have been grown on the Si(111)-(7 x 7) surface at low temperature. Individual islands are investigated concurrently with real-space and local-probe scanning tunneling microscopy and spectroscopy. Quantum size effects, manifested in the formation of new electronic bound states, redistribution of surface charge density, and oscillatory relaxations in island thickness are found to be perfectly correlated to each other.     

Measurement of B(0)(d)-B_(0)(d) mixing rate from the time evolution of dilepton events at the upsilon(4S)

We report a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on the time evolution of dilepton yields in Upsilon(4S) decays. The measurement is based on a 5.9 fb(-1) data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing Deltam(d) as a free parameter. Using both muons and electrons, we obtain Deltam(d) = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This is the first determination of Deltam(d) from time evolution measurements at the Upsilon(4S). We also place limits on possible CPT violations.