RXTE Discovery of Coherent Millisecond Pulsations during an X-ray Burst from KS 1731-260

A highly coherent 523.92+-0.05 Hz periodic X-ray signal has been observed during a type I X-ray burst from the low-mass X-ray binary system KS 1731-260 with the PCA on RXTE. The spectral evolution of the burst indicates photospheric-radius expansion and contraction. The 524 Hz signal occurred at the end of the contraction phase, lasted for ~2 s, was highly coherent (Q >~ 900), and had a pulse fraction (ratio of sinusoidal amplitude to mean count rate) of 6.2+-0.6%. KS 1731-260 is one of only three systems that have exhibited high-coherence millisecond oscillations during X-ray bursts and the first reported where the pulsations are associated with photospheric contraction. These coherent signals may be interpreted as a direct indication of the neutron star spin.Comment: 15 pages plus 4 Postscript figures; AASTeX format; submitted to Astrophysical Journal Letter

STATUS OF CROSS-SECTION DATA FOR GAS PRODUCTION FROM VANADIUM AND 26AL FROM SILICON CARBIDE IN A D-T FUSION REACTOR

ABSTRACT Current designs of fision-reactor systems seek to use radiation-resistan$ low-activation materials that support long service lifetimes and minimize radioactive-waste problems atler decommissioning. Reliable assessment of. fusion materials perfonrmnce requires accurate neutronreaction cross sections and radioactive-decay constants. The problem areas usually involve cross sections since decay parameters tend to be better known. The present L stud was motivated by two specific questions: i) Why are the V(n,np)sOTi cross section values in the ENDFLB-VI library so large (a gas production issue)? ii) How well known are the cross sections associated with producing 7.4X105 y 'Al in silicon carbide by the process 28Si(n,np+d)27Al(n,2n)2sAI (a long-lived radioactivity issue)? The energy range 14-15 MeV of the D-T fhsion neutrons is emphasized. Cross-section error bars are needed so that uncertainties in the gas and radioactivity generated over the lifetime of a reactor can be estimated. We address this issue by comparing values obtained from prominent evaluated cross-section libraries. Small differences between independent evaluations indicate that a physical quantity is well known while the opposite signals a problem. Hydrogen from 51V(n,p)5% and helium from 5*V(n,a)4*Sc are also important sources of gas in vanadium, so they too were examined. We conclude that 'lV(n p)5*TI is adequately known but 51V(n,np+d)50Ti is not. he status for helium generation data is quite good. Due to recent experimental work, 2'Al(n,2n)2GAlseems to be fairly well known. However, the situation for %i(n,np+d)27Al remains unsatisfactory

A Prospective Study of Lupus and Rheumatoid Arthritis in Relation to Deployment in Support of Iraq and Afghanistan: The Millennium Cohort Study

The objective of this study was to prospectively assess the association between deployment in support of the operations in Iraq and Afghanistan and newly reported lupus and rheumatoid arthritis while also considering the effects of demographic, behavioral, and occupational characteristics. A total of 77,047 (2001–2003) and 31,110 (2004–2006) participants completed the baseline Millennium Cohort questionnaire and were resurveyed approximately every 3 years. Longitudinal analyses were used to assess the adjusted association between deployment to Iraq and Afghanistan with and without combat exposures and newly reported disease. After adjusting, deployment was not significantly associated with newly reported lupus compared with nondeployers. However, compared with nondeployers, deployers with and without combat exposures were significantly less likely to newly report rheumatoid arthritis. Women, non-Hispanic black, and Hispanic participants had a significantly elevated risk for both diseases. Overall, deployment was not associated with an increased risk of newly reported lupus or rheumatoid arthritis

The phase diagram for the binary system indium-tellurium and electrical properties of In3Te5

The phase diagram for the binary system indium-tellurium has been clarified and corrected, particularly in the region near the composition In2Te3. This material is a potentially important semiconductor, either alone or in combination with other materials, such as Cu3Te, Ag2Te, CdTe, etc.Results of this study were obtained by correlating differential thermal analysis (DTA), chemical analyses of zone-refined ingots, microscopic analysis, and X-ray determinations.Two new phases have been identified, and the compositions of three other phases have been determined more precisely. (1) The phase In2Te (33.3 at. %Te) does not exist; the composition should be In9Te7 (43 at. %Te). The peritectic decomposition temperature is 462[deg]C. (2) The phase InTe (50.0 at. % Te) has the composition In30Te31 (50.8 at. % Te). The congruent melting point is 696[deg]C. (3) A new phase In3Te4 (57.0 at. % Te) has been found having a peritectic decomposition temperature of 650[deg]C. (4) The phase In2Te3 (60.0 at. % Te) has the composition In27Te40 (59.7 at.% Te). The congruent melting point is 667[deg]C, and there is a phase transition at about 550[deg]C. (5) A new phase In3Te5 (62.5 at. % Te) has been found, having a peritectic decomposition temperature of 625[deg]C, and a phase transition at 463[deg]C. (6) The phase In2Te5 (71.5 at. % Te) was prepared. (7) Electrical measurements on In3Te5 show a large conductivity increase associated with the phase transition at 463[deg]C. (8) Electrical measurements on zone refined In2Te3, were non-reproducible.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32121/1/0000172.pd

Four-shooter: a large format charge-coupled-device camera for the Hale telescope

We describe an astronomical camera for the 200-in. Hale telescope using four 800 X800 Texas Instruments CCDs in an optical arrangement that allows imaging of a contiguous 1600-pixel-square region of sky. The system employs reimaging optics to yield a scale of 0.33 arcsec per pixel, a good match to the best seeing conditions at Palomar Observatory. Modern high-efficiency coatings are used in the complex optical system to yield a throughput at peak efficiency of nearly 50% (including the losses in the telescope), corresponding to a quantum efficiency on the sky of about 30%. The system uses a fifth CCD in a spectroscopic channel, and it is possible to obtain simultaneous imaging and spectroscopic observations with the system. The camera may also be used in a scanning mode, in which the telescope tracking rate is offset, and the charge is clocked in the chips in such a manner as to keep the charge image aligned with the optical image. In this way, a survey for high-redshift quasars has been carried out over a large area of sky. The instrument has produced images for the most distant clusters of galaxies yet discovered as well as spectra of the most distant galaxies yet observed

Mars Aeronomy Observer: Report of the Science Working Team

The Mars Aeronomy Observer (MAO) is a candidate follow-on mission to Mars Observer (MO) in the Planetary Observer Program. The four Mariner and two Viking spacecraft sent to Mars between 1965 and 1976 have provided a wealth of information concerning Martian planetology. The Mars Observer, to be launched in 1990, will build on their results by further examining the elemental and mineralogical composition of the surface, the strength and multipolar composition of the planetary magnetic field, the gravitational field and topography, and the circulation of the lower atmosphere. The Mars Aeronomy Observer is intended to address the last major aspects of Martian environment which have yet to be investigated: the upper atmosphere, the ionsphere, and the solar wind interaction region

A FUSE Survey of Interstellar Molecular Hydrogen in the Small and Large Magellanic Clouds

We describe a moderate-resolution FUSE survey of H2 along 70 sight lines to the Small and Large Magellanic Clouds, using hot stars as background sources. FUSE spectra of 67% of observed Magellanic Cloud sources (52% of LMC and 92% of SMC) exhibit absorption lines from the H2 Lyman and Werner bands between 912 and 1120 A. Our survey is sensitive to N(H2) >= 10^14 cm^-2; the highest column densities are log N(H2) = 19.9 in the LMC and 20.6 in the SMC. We find reduced H2 abundances in the Magellanic Clouds relative to the Milky Way, with average molecular fractions = 0.010 (+0.005, -0.002) for the SMC and = 0.012 (+0.006, -0.003) for the LMC, compared with = 0.095 for the Galactic disk over a similar range of reddening. The dominant uncertainty in this measurement results from the systematic differences between 21 cm radio emission and Lya in pencil-beam sight lines as measures of N(HI). These results imply that the diffuse H2 masses of the LMC and SMC are 8 x 10^6 Msun and 2 x 10^6 Msun, respectively, 2% and 0.5% of the H I masses derived from 21 cm emission measurements. The LMC and SMC abundance patterns can be reproduced in ensembles of model clouds with a reduced H2 formation rate coefficient, R ~ 3 x 10^-18 cm^3 s^-1, and incident radiation fields ranging from 10 - 100 times the Galactic mean value. We find that these high-radiation, low-formation-rate models can also explain the enhanced N(4)/N(2) and N(5)/N(3) rotational excitation ratios in the Clouds. We use H2 column densities in low rotational states (J = 0 and 1) to derive a mean kinetic and/or rotational temperature = 82 +/- 21 K for clouds with N(H2) >= 10^16 cm^-2, similar to Galactic gas. We discuss the implications of this work for theories of star formation in low-metallicity environments. [Abstract abridged]Comment: 30 pages emulateapj, 14 figures (7 color), 7 tables, accepted for publication in the Astrophysical Journal, figures 11 and 12 compressed at slight loss of quality, see http://casa.colorado.edu/~tumlinso/h2/ for full version