Einselection without pointer states

We consider small subsystems of large, closed quantum systems that evolve according to the von Neumann equation. Without approximations and without making any special assumptions on the form of the interaction we prove that, for almost all initial states and almost all times, the off-diagonal elements of the density matrix of the subsystem in the eigenbasis of its local Hamiltonian must be small, whenever the energy difference of the corresponding eigenstates is larger than the interaction energy. This proves that decoherence with respect to the local energy eigenbasis is a natural property of weakly interacting quantum systems.Comment: published in Phys. Rev. E, 4 pages, no figures, revised introduction and conclusions, references revised and new references added, editorial change

Regulation of 92-kD gelatinase release in HL-60 leukemia cells

Matrix metalloproteinase 9 (MMP-9), also known as 92-kD type IV collagenase/gelatinase, is believed to play a critical role in tumor invasion and metastasis. Here, we report that MMP-9 was constitutively released from the human promyelocytic cell line HL-60 as determined by zymographic analysis. Tumor necrosis factor-alpha (TNF-alpha) enhanced the enzyme release threefold to fourfold and the protein kinase C (PKC) activator and differentiation inducer 12-O-tetradecanoylphorbol-13- acetate (TPA) eightfold to ninefold. Gelatinase induction by TNF-alpha and TPA was inhibited by actinomycin D or cycloheximide, indicating that de novo protein synthesis was required. Neutralizing monoclonal antibodies to TNF-alpha (anti-TNF-alpha) decreased the basal MMP-9 release of these cells. In addition, these antibodies also significantly interfered with the TPA-induced enzyme release. Agents that inhibit TNF-alpha expression in HL-60 cells, such as pentoxifylline and dexamethasone, completely abrogated both the constitutive and TPA-evoked MMP-9 release. Diethyldithiocarbamate, which is known to stimulate TNF-alpha production in HL-60 cells, exerted a positive effect on MMP-9 release in untreated cells but was inhibitory in TPA-treated HL-60 cells. The PKC inhibitor staurosporine at low concentrations (100 ng/mL) caused a significant augmentation of MMP-9 release in untreated cultures that was blocked by the addition of anti-TNF-alpha. High concentrations (2 mumol/L) of staurosporine completely abolished the extracellular enzyme activity both in untreated and TPA-stimulated cells. These results suggest, that TNF- alpha is required for basal and PKC-mediated MMP-9 release in HL-60 leukemia cells. Thus, MMP-9 secretion may be regulated by TNF-alpha not only in a paracrine but also in an autocrine fashion. This may potentiate the matrix degradative capacity of immature leukemic cells in the processes of bone marrow egress and the evasion of these cells into peripheral tissue

Anomalous flows in a sunspot penumbra

High-resolution spectropolarimetric observations of active region NOAA 11271 were obtained with the spectro-polarimeter on board Hinode to analyze the properties of an anomalous flow in the photosphere in a sunspot penumbra. We detect a blue-shifted feature that appeared on the limb-side penumbra of a sunspot and that was present intermittently during the next two hours. It exhibited a maximum blue-shift of 1.6 km/s, an area of 5.2 arcsec^2, and an uninterrupted lifetime of 1 hr. The blue-shifted feature, when present, lies parallel to red-shifts. Both blue and red shifts flank a highly inclined/horizontal magnetic structure that is radially oriented in the penumbra. The low-cadence SP maps reveal changes in size, radial position in the penumbra and line-of-sight velocity of the blue-shifted feature, from one scan to the other. There was an increase of nearly 500 G in the field strength and a marginal reduction in the field inclination of about 10 deg with the onset of the blue-shifts. In the chromosphere, intense, arc-shaped brightenings were observed close to the location of the blue-shifts, that extend from the edge of the umbral core to the penumbra-quiet Sun boundary. The strongest and largest brightenings were observed about 30 min after the strongest blue-shifts were detected at the photosphere. The close spatial proximity of the two phenomenon strongly suggests a causal relationship. The blue-shifted feature represents plasma motion that could be related to a magnetic structure that rises in the solar atmosphere and subsequently reconnects with the ambient chromospheric magnetic field of the sunspot or an inverse Evershed flow, which would be unique in the photosphere. This transient phenomena is presumably related to the dynamic stability of the sunspot because the corresponding umbral core separated two days later at the location of the blue-shifts and fragmented subsequently.Comment: Accepted for publication in A&A: 8 pages, 8 figure

Scanning electron microscope/energy dispersive x ray analysis of impact residues in LDEF tray clamps

Detailed optical scanning of tray clamps is being conducted in the Facility for the Optical Inspection of Large Surfaces at JSC to locate and document impacts as small as 40 microns in diameter. Residues from selected impacts are then being characterized by Scanning Electron Microscopy/Energy Dispersive X-ray Analysis at CNES. Results from this analysis will be the initial step to classifying projectile residues into specific sources

Helmholtz bright spatial solitons and surface waves at power-law optical interfaces

We consider arbitrary-angle interactions between spatial solitons and the planar boundary between two optical materials with a single power-law nonlinear refractive index. Extensive analysis has uncovered a wide range of new qualitative phenomena in non-Kerr regimes. A universal Helmholtz-Snell law describing soliton refraction is derived using exact solutions to the governing equation as a nonlinear basis. New predictions are tested through exhaustive computations, which have uncovered substantially enhanced Goos-Hänchen shifts at some non-Kerr interfaces. Helmholtz nonlinear surface waves are analyzed theoretically, and their stability properties are investigated numerically for the first time. Interactions between surface waves and obliquely-incident solitons are also considered. Novel solution behaviours have been uncovered, which depend upon a complex interplay between incidence angle, medium mismatch parameters, and the power-law nonlinearity exponent