Adhesive for aluminum withstands cryogenic temperatures

Polyurethane adhesive mixed to various proportions with milled glass fibers match the thermal characteristics of 2014-T6 aluminum at cryogenic temperatures

ASCA Observations of the Seyfert 2 Galaxy NGC 7582: An Obscured and Scattered View of the Hidden Nucleus

ASCA observations of the Seyfert 2 galaxy NGC 7582 revealed it was highly variable on the timescale of $\sim2\times10^4$ s in the hard X-ray (2-10 keV) band, while the soft X-ray (0.5-2 keV) flux remained constant during the observations. The spectral analysis suggests that this object is seen through an obscuring torus with the thickness of N$_{\rm H}\sim1.0\times 10^{23}\rm cm^{-2}$. The hard X-ray is an absorbed direct continuum from a hidden Seyfert 1 nucleus; the soft X-ray is dominated by the scattered central continuum from an extended spatial region. Thus we have an obscured/absorbed and a scattered view of this source as expected from the unification model for Seyfert galaxies. More interestingly, the inferred X-ray column was observed to increase by $\sim4\times10^{22} \rm cm^{-2}$ from 1994 to 1996, suggesting a ``patchy'' torus structure, namely the torus might be composed of many individual clouds. The observed iron line feature near 6.4 keV with the equivalent width of 170 eV is also consistent with the picture of the transmission of nuclear X-ray continuum through a non-uniform torus.Comment: 10 pages, 6 figures. To be appear in PASJ 50 No.5 (1998 Oct.25 issue

Pressure-induced Superconductivity in CaLi2

A search for superconductivity has been carried out on the hexagonal polymorph of Laves-phase CaLi2, a compound for which Feng, Ashcroft, and Hoffmann predict highly anomalous behavior under pressure. No superconductivity is observed above 1.10 K at ambient pressure. However, high-pressure ac susceptibility and electrical resistivity studies to 81 GPa reveal bulk superconductivity in CaLi2 at temperatures as high as 13 K. The normal-state resistivity shows a dramatic increase with pressure.Comment: bulk superconductivity in CaLi2 now confirme

Random background charges and Coulomb blockade in one-dimensional tunnel junction arrays

We have numerically studied the behavior of one dimensional tunnel junction arrays when random background charges are included using the ``orthodox'' theory of single electron tunneling. Random background charge distributions are verified in both amplitude and density. The use of a uniform array as a transistor is discussed both with and without random background charges. An analytic expression for the gain near zero gate voltage in a uniform array with no background charges is derived. The gate modulation with background charges present is simulated.Comment: 10 pages, 7 figure

Spin Polarized versus Chiral Condensate in Quark Matter at Finite Temperature and Density

It is shown that the spin polarized condensate appears in quark matter at high baryon density and low temperature due to the tensor-type four-point interaction in the Nambu-Jona-Lasinio-type model as a low energy effective theory of quantum chromodynamics. It is indicated within this low energy effective model that the chiral symmetry is broken again by the spin polarized condensate as increasing the quark number density, while the chiral symmetry restoration occurs in which the chiral condensate disappears at a certain density.Comment: 25 pages, 9 figure

An investigation of star formation and dust attenuation in major mergers using ultraviolet and infrared data

Merger processes play an important role in galaxy formation and evolution. To study the influence of merger processes on the evolution of dust properties and cosmic star formation rate, we investigate a local sample of major merger galaxies and a control sample of isolated galaxies using GALEX ultraviolet (UV) and Spitzer infrared (IR) images. Through a statistical study, we find that dust attenuation in merger galaxies is enhanced with respect to isolated galaxies. We find this enhancement is contributed mainly by spiral galaxies in spiral-spiral (S-S) pairs, and increases with the increasing stellar mass of a galaxy. Combining the IR and UV parts of star formation rates (SFRs), we then calculated the total SFRs and specific star formation rates (SSFRs). We find the SSFRs to be enhanced in merger galaxies. This enhancement depends on galaxy stellar mass and the companion's morphology, but depends little on whether the galaxy is a primary or secondary component or on the separation between two components. These results are consistent with a previous study based only on IR images. In addition, we investigate the nuclear contributions to SFRs. SFRs in paired galaxies are more concentrated in the central part of the galaxies than in isolate galaxies. Our studies of dust attenuation show that the nuclear parts of pairs most resemble ULIRGs. Including UV data in the present work not only provides reliable information on dust attenuation, but also refines analyses of SFRs.Comment: 21 pages, 21 figure

Single-Electron Traps: A Quantitative Comparison of Theory and Experiment

We have carried out a coordinated experimental and theoretical study of single-electron traps based on submicron aluminum islands and aluminum oxide tunnel junctions. The results of geometrical modeling using a modified version of MIT's FastCap were used as input data for the general-purpose single-electron circuit simulator MOSES. The analysis indicates reasonable quantitative agreement between theory and experiment for those trap characteristics which are not affected by random offset charges. The observed differences between theory and experiment (ranging from a few to fifty percent) can be readily explained by the uncertainty in the exact geometry of the experimental nanostructures.Comment: 17 pages, 21 figures, RevTex, eps