Evidence for GeV emission from the Galactic Center Fountain

The region near the Galactic center may have experienced recurrent episodes of injection of energy in excess of $\sim$ 10$^{55}$ ergs due to repeated starbursts involving more than $\sim$ 10$^4$ supernovae. This hypothesis can be tested by measurements of $\gamma$-ray lines produced by the decay of radioactive isotopes and positron annihilation, or by searches for pulsars produced during starbursts. Recent OSSE observations of 511 keV emission extending above the Galactic center led to the suggestion of a starburst driven fountain from the Galactic center. We present EGRET observations that might support this picture.Comment: 5 pages, 1 embedded Postscript figure. To appear in the Proceedings of the Fourth Compton Symposiu

Fluid machines: Expanding the limits, past and future

During the 40 yr period from 1940 to 1980, the capabilities and operating limits of fluid machines were greatly extended. This was due to a research program, carried out to meet the needs of aerospace programs. Some of the events are reviewed. Overall advancements of all machinery components are discussed followed by a detailed examination of technology advancements in axial compressors and pumps. Future technology needs are suggested

Search for GRB afterglows in the ROSAT all-sky survey

We report on the status of our search for X-ray afterglows of gamma-ray bursts (GRBs) using the ROSAT all-sky survey data. The number of potential X-ray afterglow candidates with respect to the expected number of beamed GRBs allows to constrain the relative beaming angles of GRB emission and afterglow emission at about 1-5 hrs after the GRB.Comment: 3 pages A&A style, 1 color ps-figure; To appear in A&A Suppl. Series, Proc. of Rome 1998 GRB workshop, also available from http://www.aip.de/~jcg/publis.htm

The use of pure carbon for permanent percutaneous electrical connector systems

Pure carbon was used as an electrode in the clinical application of long-term neuromuscular stimulation, as well as a connector for permanent neuroelectrodes. The history of this material and some examples of the material in use are presented

Strong photon non-linearities and photonic Mott insulators

We show, that photon non-linearities in electromagnetically induced transparency can be at least one order of magnitude larger than predicted in all previous approaches. As an application we demonstrate that, in this regime they give rise to very strong photon - photon interactions which are strong enough to make an experimental realization of a photonic Mott insulator state feasible in arrays of coupled ultra high-Q micro-cavities.Comment: minor changes, to appear in Phys. Rev. Let

Probing the evolving massive star population in Orion with kinematic and radioactive tracers

We assemble a census of the most massive stars in Orion, then use stellar isochrones to estimate their masses and ages, and use these results to establish the stellar content of Orion's individual OB associations. From this, our new population synthesis code is utilized to derive the history of the emission of UV radiation and kinetic energy of the material ejected by the massive stars, and also follow the ejection of the long-lived radioactive isotopes 26Al and 60Fe. In order to estimate the precision of our method, we compare and contrast three distinct representations of the massive stars. We compare the expected outputs with observations of 26Al gamma-ray signal and the extent of the Eridanus cavity. We find an integrated kinetic energy emitted by the massive stars of 1.8(+1.5-0.4)times 10^52 erg. This number is consistent with the energy thought to be required to create the Eridanus superbubble. We also find good agreement between our model and the observed 26Al signal, estimating a mass of 5.8(+2.7-2.5) times 10^-4 Msol of 26Al in the Orion region. Our population synthesis approach is demonstrated for the Orion region to reproduce three different kinds of observable outputs from massive stars in a consistent manner: Kinetic energy as manifested in ISM excavation, ionization as manifested in free-free emission, and nucleosynthesis ejecta as manifested in radioactivity gamma-rays. The good match between our model and the observables does not argue for considerable modifications of mass loss. If clumping effects turn out to be strong, other processes would need to be identified to compensate for their impact on massive-star outputs. Our population synthesis analysis jointly treats kinematic output and the return of radioactive isotopes, which proves a powerful extension of the methodology that constrains feedback from massive stars.Comment: Accepted for publication in A&A, 10 page

Minimizing the Pervasiveness of Women’s Personal Experiences of Gender Discrimination

Given the Rejection-Identification Model (Branscombe, et al., 1999) which shows that perceiving discrimination to be pervasive is a negative experience, it was suggested that there would be conditions under which women would instead minimize the pervasiveness of discrimination. Study 1 (N = 91) showed that when women envisioned themselves in a situation of academic discrimination, they defined it as pervasive but when they experienced a similar laboratory simulation of academic discrimination, its pervasiveness was minimized. Study 2 (N = 159) showed that women who envisioned themselves experiencing discrimination minimized its pervasiveness more so than women reading about discrimination happening to someone else. Further, mediation analysis showed that minimizing the pervasiveness enhanced positive affect about personal discrimination. Implications for minimizing on both an individual and social level are discussed

Spin Domains Generate Hierarchical Ground State Structure in J=+/-1 Spin Glasses

Unbiased samples of ground states were generated for the short-range Ising spin glass with Jij=+/-1, in three dimensions. Clustering the ground states revealed their hierarchical structure, which is explained by correlated spin domains, serving as cores for macroscopic zero energy "excitations".Comment: 4 pages, 5 figures, accepted to Phys. Rev. Let