A compact 90 kilowatt electric heat source for heating inert gases to 1700 F

Design and fabrication of compact electric heat source for heating inert gase

Ground state of a confined Yukawa plasma

The ground state of an externally confined one-component Yukawa plasma is derived analytically. In particular, the radial density profile is computed. The results agree very well with computer simulations on three-dimensional spherical Coulomb crystals. We conclude in presenting an exact equation for the density distribution for a confinement potential of arbitrary geometry.Comment: 5 pages, 4 figure

Consciousness science : real progress and lingering misconceptions.

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Assessment of Damage to Nucleic Acids and Repair Machinery in Salmonella typhimurium Exposed to Chlorine

Water disinfection is usually evaluated using mandatory methods based on cell culturability. However, such methods do not consider the potential of cells to recover, which should also be kept as low as possible. In this paper, we hypothesized that a successful disinfection is achieved only when the applied chlorine leads to both intracellular nucleic acid damage and strong alterations of the DNA repair machinery. Monitoring the SOS system responsiveness with a umuC’-‘lacZ reporter fusion, we found that the expression of this important cellular machinery was altered after the beginning of membrane permeabilization but prior to the total decline of both the cell culturability and the nucleic acid integrity as revealed by Sybr-II staining. Rapid measurement of such nucleic acid alterations by fluorochrome-based staining could be used as an alternative method for assessing the effectiveness of disinfection with chlorine

Velocity Analysis of Multi-Receiver Full Waveform Acoustic Logging Data In Open and Cased Holes

Average semblance and maximum-likelihood spectral analyses are applied to synthetic and field full waveform acoustic logging data to determine formation velocities. Of particular interest is the ability of these methods to resolve the P and shear/pseudo Rayleigh arrivals in data from poorly-bonded cased boreholes. In synthetic open-hole data the velocity analyses yield results within 4% of the true velocities. Results from synthetic well-bonded cased hole data are generally as good as those from the open hole data. However, if the formation P-wave velocity is within roughly 10% of the plate velocity of the steel pipe (about 5.3-5.5 km/s), then there may be a resonance effect that appears to slow down the P wave slightly (on the order of 6%). For cased-hole models with no steel/cement bonding (the free-pipe situation), the measured P-wave velocities are typically 6 to 8% less than the actual formation velocities. If the formation S-wave velocity is greater than about 2.5 km/s, the S-wave velocity estimate may also be 6 to 8% low. Furthermore, increasing the thickness of either the cement layer or the fluid layer between the pipe and the cement further decreases the formation velocity estimates. Also, if the P-wave velocity is within roughly 15% of the velocity of the steel arrival, the P wave may not be resolved by the semblance method unless the data is first low-pass filtered. Initial tests show that this filtering process may adversely affect the final P-wave velocity estimate, but the details of this type of approach have not been studied. The P wave is resolved. by spectral analysis of the original, unfiltered data. For cased-hole models with no cement/formation bonding (the unbonded-casing situation), formation S-wave velocities are estimated to within 3% relative error, and the formation P-wave velocity is estimated to within 2% error in a slow formation. However, for P-wave velocities between 3.4 km/s and 5.94 km/a, the P wave cannot be resolved by spectral analysis, and it is resolved by the semblance method only in the model with the low velocity (3.4 km/s).Massachusetts Institute of Technology. Full Waveform Acoustic Logging ConsortiumPhillips Petroleum Fellowshi

Seismic Imaging Of The Velocity Structure And The Location Of A Hydrofrac In A Geothermal Reservoir

The Los Alamos Hot Dry Rock Reservoir is an experimental geothermal project in north-central New Mexico. A fractured zone was created within otherwise impermeable igneous and metamorphic rock by injecting water into a borehole under high pressure, at about 3.5 km depth. During the injection process, the seismic waves created by the fracturing events were recorded by seismometers located in four nearby boreholes. A subset of the arrival times from these microearthquakes is iteratively inverted for the three-dimensional P-wave and S-wave velocity structures and the hypocenter parameters, using the separation of parameters technique. The inversion results indicate that the P-wave and S-wave velocities decrease by at least 20% within the fractured zone. Also, the hypocenters are rotated into a more compact distribution, elative to the initiallocations found using a homogeneous velocity model, suggesting that the hypocenter locations are significantly improved.United States. Dept. of Energy (Grant DE-FG02-86ER136360)Massachusetts Institute of Technology. Full Waveform Acoustic Logging ConsortiumPhillips Petroleum Fellowshi

Very Luminous Carbon Stars in the Outer Disk of the Triangulum Spiral Galaxy

Stars with masses in the range from about 1.3 to 3.5 Mo pass through an evolutionary stage where they become carbon stars. In this stage, which lasts a few Myr, these stars are extremely luminous pulsating giants. They are so luminous in the near-infrared that just a few of them can double the integrated luminosity of intermediate-age (0.6 to 2 Gyr) Magellanic Cloud clusters at 2.2 microns. Astronomers routinely use such near-infrared observations to minimize the effects of dust extinction, but it is precisely in this band that carbon stars can contribute hugely. The actual contribution of carbon stars to the outer disk light of evolving spiral galaxies has not previously been morphologically investigated. Here we report new and very deep near-IR images of the Triangulum spiral galaxy M33=NGC 598, delineating spectacular arcs of carbon stars in its outer regions. It is these arcs which dominate the near-infrared m=2 Fourier spectra of M33. We present near-infrared photometry with the Hale 5-m reflector, and propose that the arcs are the signature of accretion of low metallicity gas in the outer disk of M33.Comment: 4 pages, 4 figures. Revised version submitted to A&A Letter

Quasi-phase-matched Faraday rotation in semiconductor waveguides with a magnetooptic cladding for monolithically integrated optical isolators

Strategies are developed for obtaining nonreciprocal polarization mode conversion, also known as Faraday rotation, in waveguides in a format consistent with silicon-on-insulator or III–V semiconductor photonic integrated circuits. Fabrication techniques are developed using liftoff lithography and sputtering to obtain garnet segments as upper claddings, which have an evanescent wave interaction with the guided light. A mode solver approach is used to determine the modal Stokes parameters for such structures, and design considerations indicate that quasi-phase-matched Faraday rotation for optical isolator applications could be obtained with devices on the millimeter length scale

Compact electric heater

Forced convection electric heater heats inert gas flows to temperatures of from 1250 to 1650 deg F and tests Brayton power systems for advanced spacecraft. Heater has two basic components, a heat exchanger core and a containment vessel