The BIOSIS data base: Evaluation of its indexes and the STRATBLDR, CHEMFILE, STAIRS and DIALOG systems for on-line searching

An IBM-developed program, STAIRS, was selected for performing a search on the BIOSIS file. The evaluation of the hardware and search systems and the strategies used are discussed. The searches are analyzed by type of end user

Little IIB Matrix Model

We study the zero-dimensional reduced model of D=6 pure super Yang-Mills theory and argue that the large N limit describes the (2,0) Little String Theory. The one-loop effective action shows that the force exerted between two diagonal blocks of matrices behaves as 1/r^4, implying a six-dimensional spacetime. We also observe that it is due to non-gravitational interactions. We construct wave functions and vertex operators which realize the D=6, (2,0) tensor representation. We also comment on other "little" analogues of the IIB matrix model and Matrix Theory with less supercharges.Comment: 17 pages, references adde

Kepler problem in Dirac theory for a particle with position-dependent mass

Exact solution of Dirac equation for a particle whose potential energy and mass are inversely proportional to the distance from the force centre has been found. The bound states exist provided the length scale $a$ which appears in the expression for the mass is smaller than the classical electron radius $e^2/mc^2$. Furthermore, bound states also exist for negative values of $a$ even in the absence of the Coulomb interaction. Quasirelativistic expansion of the energy has been carried out, and a modified expression for the fine structure of energy levels has been obtained. The problem of kinetic energy operator in the Schr\"odinger equation is discussed for the case of position-dependent mass. In particular, we have found that for highly excited states the mutual ordering of the inverse mass and momentum operator in the non-relativistic theory is not important.Comment: 9 page

Comparison of laboratory calibrations of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) at the beginning and end of the first flight season

Spectral and radiometric calibrations of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) were performed in the laboratory in June and November, 1987, at the beginning and end of the first flight season. Those calibrations are described along with changes in instrument characteristics that occurred during the flight season as a result of factors such as detachment of the optical fibers to two of the four AVIRIS spectrometers, degradation in the optical alignment of the spectrometers due to thermally-induced and mechanical warpage, and breakage of a thermal blocking filter in one of the spectrometers. These factors caused loss of signal in three spectrometers, loss of spectral resolution in two spectrometers, and added uncertainty in the radiometry of AVIRIS. Results from in-flight assessment of the laboratory calibrations are presented. A discussion is presented of improvements made to the instrument since the end of the first flight season and plans for the future. Improvements include: (1) a new thermal control system for stabilizing spectrometer temperatures, (2) kinematic mounting of the spectrometers to the instrument rack, and (3) new epoxy for attaching the optical fibers inside their mounting tubes

Effects of the background radiation on radio pulsar and supernova remnant searches and the birth rates of these objects

In different directions of the Galaxy the Galactic background radio radiation and radiation of complex star formation regions which include large number of OB associations have different influences on radio pulsar (PSR) and supernova remnant (SNR) searches. In this work we analyse the effects of these background radiations on the observations of PSRs at 1400 MHz and SNRs at 1000 MHz. In the interval l=0$^o$$\pm60^o$ the PSRs with flux F$_{1400}$$>$0.2 mJy and the SNRs with surface brightness $\Sigma$$>10^{-21}$ Wm$^{-2}$Hz$^{-1}$sr$^{-1}$ are observable for all values of l and b. All the SNRs with $\Sigma$$>3\times10^{-22}$ Wm$^{-2}$Hz$^{-1}$sr$^{-1}$ can be observed in the interval 60$^o$$<$l$<300^o$. We have examined samples of PSRs and SNRs to estimate the birth rates of these objects in the region up to 3.2 kpc from the Sun and also in the Galaxy. The birth rate of PSRs is about one in 200 years and the birth rate of SNRs is about one in 65 years in our galaxy.Comment: revised versio

Refractive Index Enhancement with Vanishing Absorption in an Atomic Vapor

We report a proof-of-principle experiment where the refractive index of an atomic vapor is enhanced while maintaining vanishing absorption of the beam. The key idea is to drive alkali atoms in a vapor with appropriate control lasers and induce a gain resonance and an absorption resonance for a probe beam in a two-photon Raman configuration. The strength and the position of these two resonances can be manipulated by changing the parameters of the control lasers. By using the interference between these two resonances, we obtain an enhanced refractive index without an increase in the absorption.Comment: 11 pages, 4 figure

On the nature of the residual meson-meson interaction from simulations with a QED2+1{}_{2+1} model

A potential between mesons is extracted from 4-point functions within lattice gauge theory taking 2+1 dimensional QED as an example. This theory possesses confinement and dynamical fermions. The resulting meson-meson potential has a short-ranged hard repulsive core and the expected dipole-dipole forces lead to attraction at intermediate distances. Sea quarks lead to a softer form of the total potential.Comment: 4 pages, uuencoded tar-compressed postscript file, contribution to Lattice'9

Astrometric Galactic maser measurements cross-matched with Gaia

Using the VLBA, the BeSSeL survey has provided distances and proper motions of young massive stars, allowing an accurate measure of the Galactic spiral structure. By the same technique, we are planning to map the inner Galaxy using positions and velocities of evolved stars (provided by the BAaDE survey). These radio astrometric measurements (BeSSeL and BAaDE) will be complementary to Gaia results and the overlap will provide important clues on the intrinsic properties and population distribution of the stars in the bulge.Comment: To appear in the Proceedings of the IAU Symposium No. 334: "Rediscovering our Galaxy