Analysis of low resolution mass spectra

Computer program determines gas constituents from measurements of mass/peak-height spectrum from residual gas analyzer. Applications of program include residual gas analysis for work in space environmental simulators, space environment contamination, and air pollution monitoring

Region of the anomalous compression under Bondi-Hoyle accretion

We investigate the properties of an axisymmetric non-magnetized gas flow without angular momentum on a small compact object, in particular, on a Schwarzschild black hole in the supersonic region near the object; the velocity of the object itself is assumed to be low compared to the speed of sound at infinity. First of all, we see that the streamlines intersect (i.e., a caustic forms) on the symmetry axis at a certain distance $r_x$ from the center on the front side if the pressure gradient is neglected. The characteristic radial size of the region, in which the streamlines emerging from the sonic surface at an angle no larger than $\theta_0$ to the axis intersect, is $\Delta r= r_x\theta^2_0/3.$ To refine the flow structure in this region, we numerically compute the system in the adiabatic approximation without ignoring the pressure. We estimate the parameters of the inferred region with anomalously high matter temperature and density accompanied by anomalously high energy release.Comment: 10 pages, 2 figure

Reflective Ghost Imaging through Turbulence

Recent work has indicated that ghost imaging may have applications in standoff sensing. However, most theoretical work has addressed transmission-based ghost imaging. To be a viable remote-sensing system, the ghost imager needs to image rough-surfaced targets in reflection through long, turbulent optical paths. We develop, within a Gaussian-state framework, expressions for the spatial resolution, image contrast, and signal-to-noise ratio of such a system. We consider rough-surfaced targets that create fully developed speckle in their returns, and Kolmogorov-spectrum turbulence that is uniformly distributed along all propagation paths. We address both classical and nonclassical optical sources, as well as a computational ghost imager.Comment: 13 pages, 3 figure

A Comparison of Quartz Crystal Microbalance Measurements with Mass Spectrometer Determinations

An experimental program was undertaken in which mass accretion rates, as determined by a liquid nitrogen cooled quartz crystal microbalance, were compared with the mass flux rates, as determined by both a cycloidal type and a quadrupole type residual gas analyzer for five simple materials. The data indicate a high degree of correlation between these instruments insofar as the shape of the curves. There are large variations however among the absolute values

Pilot trial of fk 506 in the management of steroid-resistant nephrotic syndrome

Seven patients with steroid-resistant nephrotic syndrome were treated with FK 506 monotherapy. Four patients were children with focal sclerosing glomerulonephritis (FSGS). Three of these had evldence for chronic progressive renal disease consisting of interstitial fibrosis and tubular atrophy on pretreatment renal biopsies. Two patients had also failed cyclosporin A (CsA), two cyclophosphamide, and one chlorambucil prior to treatment with FK 506. Three patients were adults wlth mesangial proliferative. membranoproliferative, and membranous glomerulonephritis. Three patterns of response were noted: (1) a reduction in proteinuria to normal levels, (2) partial response (50% reduction) or; (3) no improvement. All patients except one experienced at least a 50% reduction in protein excretion at some time during FK 506 therapy. Two of the children and one adult reduced protein excretion to essentially normal values. One patient had no sustained reduction In Droteln excretion and is considered to be a treatment fallure, although her protein excretion was approximately 50% of pretreatment values intermittently. The drug was generally well tolerated. The most common side-effect was nephrotoxlclty, whlch was reversible. These encouraging results suggest that FK 506 monotherapy may be effective in controlling the proteinuria of somc patlents with steroid-resistant nephrotic syndrome The use of this drug may extend our understanding of the role of T lymphocytes and cytokines in the pathogenesls of glomerulonephritis. Further study of this agent In a larger population of patlents is warranted. © 1993 European Dialysis and Transplant Assoiation-European Renal Association

Practical high-dimensional quantum key distribution with decoy states

High-dimensional quantum key distribution (HD-QKD) allows two parties to generate multiple secure bits of information per detected photon. In this work, we show that decoy state protocols can be practically implemented for HD-QKD using only one or two decoy states. HD-QKD with two decoy states, under realistic experimental constraints, can generate multiple secure bits per coincidence at distances over 200 km and at rates similar to those achieved by a protocol with infinite decoy states. Furthermore, HD-QKD with only one decoy state is practical at short distances, where it is almost as secure as a protocol with two decoy states. HD-QKD with only one or two decoy states can therefore be implemented to optimize the rate of secure quantum communications.Comment: 11 pages, 3 figure

Optical properties of current carrying molecular wires

We consider several fundamental optical phenomena involving single molecules in biased metal-molecule-metal junctions. The molecule is represented by its highest occupied and lowest unoccupied molecular orbitals, and the analysis involves the simultaneous consideration of three coupled fluxes: the electronic current through the molecule, energy flow between the molecule and electron-hole excitations in the leads and the incident and/or emitted photon flux. Using a unified theoretical approach based on the non-equilibrium Green function method we derive expressions for the absorption lineshape (not an observable but a ueful reference for considering yields of other optical processes) and for the current induced molecular emission in such junctions. We also consider conditions under which resonance radiation can induce electronic current in an unbiased junction. We find that current driven molecular emission and resonant light induced electronic currents in single molecule junctions can be of observable magnitude under appropriate realizable conditions. In particular, light induced current should be observed in junctions involving molecular bridges that are characterized by strong charge transfer optical transitions. For observing current induced molecular emission we find that in addition to the familiar need to control the damping of molecular excitations into the metal substrate the phenomenon is also sensitive to the way in which the potential bias si distributed on the junction.Comment: 56 pages, 8 figures; submitted to JC

Dark energy: a quantum fossil from the inflationary Universe?

The discovery of dark energy (DE) as the physical cause for the accelerated expansion of the Universe is the most remarkable experimental finding of modern cosmology. However, it leads to insurmountable theoretical difficulties from the point of view of fundamental physics. Inflation, on the other hand, constitutes another crucial ingredient, which seems necessary to solve other cosmological conundrums and provides the primeval quantum seeds for structure formation. One may wonder if there is any deep relationship between these two paradigms. In this work, we suggest that the existence of the DE in the present Universe could be linked to the quantum field theoretical mechanism that may have triggered primordial inflation in the early Universe. This mechanism, based on quantum conformal symmetry, induces a logarithmic, asymptotically-free, running of the gravitational coupling. If this evolution persists in the present Universe, and if matter is conserved, the general covariance of Einstein's equations demands the existence of dynamical DE in the form of a running cosmological term whose variation follows a power law of the redshift.Comment: LaTeX, 14 pages, extended discussion. References added. Accepted in J. Phys. A: Mathematical and Theoretica

Propagation of cosmic rays and new evidence for distributed acceleration

The origin and propagation of cosmic rays in terms of conventional and supplementary newer assumptions were explored. Cosmic rays are considered to be accelerated by supernoava shock waves and to traverse clouds in the source region. After rigidity-dependent escape from these clouds into interstellar space, cosmic rays are further accelerated by the weakened shocks of old supernova remnants and then pass through additional material. The distributed acceleration hypothesis is discussed with emphasis on recent data on the abundances of cosmic-ray isotopes of N above 1 GeV/u and of He near 6 GeV/u