New polymers for low-gravity purification of cells by phase partitioning

A potentially powerful technique for separating different biological cell types is based on the partitioning of these cells between the immiscible aqueous phases formed by solution of certain polymers in water. This process is gravity-limited because cells sediment rather than associate with the phase most favored on the basis of cell-phase interactions. In the present contract we have been involved in the synthesis of new polymers both to aid in understanding the partitioning process and to improve the quality of separations. The prime driving force behind the design of these polymers is to produce materials which will aid in space experiments to separate important cell types and to study the partitioning process in the absence of gravity (i.e., in an equilibrium state)

New polymers for phase partitioning

The synthesizing of several polyethylene glycols having crown ethers attached is reported. This work led to the identification of three new polymer types which promise to be more effective at selectively binding specific cell types. Work was completed on identification of chemical properties of the new polymer crowns and on development of new techniques for determination of polymer-phase composition

Improvements in micromanipulators

Design, operation, and application of micromanipulators in biological researc

On the Connection Between 2d Topological Gravity and the Reduced Hermitian Matrix Model

We discuss how concepts such as geodesic length and the volume of space-time can appear in 2d topological gravity. We then construct a detailed mapping between the reduced Hermitian matrix model and 2d topological gravity at genus zero. This leads to a complete solution of the counting problem for planar graphs with vertices of even coordination number. The connection between multi-critical matrix models and multi-critical topological gravity at genus zero is studied in some detail.Comment: 29 pages, LaTe

Dipole-Field Contributions to Geometric-Phase-Induced False Electric-Dipole Moment Signals for Particles in Traps

It has been shown in an earlier publication that magnetic field gradients applied to particles in traps can induce Larmor frequency shifts that may falsely be interpreted as electric-dipole moment (EDM) signals. This study has now been extended to include nonuniform magnetic field gradients due to the presence of a local magnetic dipole. It is found that, in the high orbit-frequency regime, the magnitude of the shifts can be enhanced beyond the simple expectation of proportionality to the volume-averaged magnetic-field gradient.Comment: 2 pages, no figure

Fixed wing CCW aerodynamics with and without supplementary thrust deflection

The concept of circulation control was successfully demonstrated in flight using an A-6 aircraft. Circulation control can provide an aircraft with STOL performance of heavy lift capability. For ship based Naval aircraft the lower takeoff and landing velocities result in reduced deck gear and wind over the deck requirements. Circulation control airfoils can be mechanically less complex and lightweight compared to multi-element high lift airfoils

Computer program for solving compressible nonsimilar-boundary-layer equations for laminar, transitional, or turbulent flows of a perfect gas

A computer program is described which solves the compressible laminar, transitional, or turbulent boundary-layer equations for planar or axisymmetric flows. Three-point implicit difference relations are used to reduce the momentum and energy equations to finite-difference form. These equations are solved simultaneously without iteration. Turbulent flow is treated by the inclusion of either a two-layer eddy-viscosity model or a mixing-length formulation. The eddy conductivity is related to the eddy viscosity through a static turbulent Prandtl number which may be an arbitrary function of the distance from the wall boundary. The transitional boundary layer is treated by the inclusion of an intermittency function which modifies the fully turbulent model. The laminar-boundary-layer equations are recovered when the intermittency is zero, and the fully turbulent equations are solved when the intermittency is unity

Detailed Comparison of Next-to-Leading Order Predictions for Jet Photoproduction at HERA

The precision of new HERA data on jet photoproduction opens up the possibility to discriminate between different models of the photon structure. This requires equally precise theoretical predictions from perturbative QCD calculations. In the past years, next-to-leading order calculations for the photoproduction of jets at HERA have become available. Using the kinematic cuts of recent ZEUS analyses, we compare the predictions of three calculations for different dijet and three-jet distributions. We find that in general all three calculations agree within the statistical accuracy of the Monte Carlo integration yielding reliable theoretical predictions. In certain restricted regions of phase space, the calculations differ by up to 5%.Comment: 10 pages, 7 eps-figures. To appear in the Proceedings of the Workshop on ``Monte Carlo Generators for HERA Physics'', Hamburg 1998/9

X-ray Emission from the Radio Jet in 3C 120

We report the discovery of X-ray emission from a radio knot at a projected distance of 25" from the nucleus of the Seyfert galaxy, 3C 120. The data were obtained with the ROSAT High Resolution Imager (HRI). Optical upper limits for the knot preclude a simple power law extension of the radio spectrum and we calculate some of the physical parameters for thermal bremsstrahlung and synchrotron self-Compton models. We conclude that no simple model is consistent with the data but if the knot contains small regions with flat spectra, these could produce the observed X-rays (via synchrotron emission) without being detected at other wavebands.Comment: 6 pages latex plus 3 ps/eps figures. Uses 10pt.sty and emulateapj.sty. Accepted for publication in the ApJ (6 Jan 99

The prompt gamma-ray emission of novae

Classical novae are potential gamma-ray emitters, because of the disintegration of some radioactive nuclei synthesized during the explosion. Some short-lived isotopes (such as 13N and 18F), as well as the medium-lived 22Na, decay emitting positrons, which annihilate with electrons and thus are responsible for the prompt emission of gamma-rays from novae. This emission consists of a 511 keV line plus a continuum between 20 and 511 keV, and is released before the maximum in visual luminosity, i.e., before the discovery of the nova. The main characteristics of this prompt emission, together with the related uncertainties (both of nuclear and hydrodynamical origin, with a particular emphasis on the influence of the envelope properties) and prospects for detectability are analyzed in this paper.Comment: 6 pages, 3 figures (6 PS files), to appear in New Astronomy Reviews (Proceedings of the Ringberg Workshop "Astronomy with Radioactivities III"