9,328 research outputs found
Homiletics: Outlines on the Swedish Gospels (Alternate Series)
Outlines on the Swedish Gospels (Alternate Series
LWR fuel performance analysis : fuel cracking and relocation
"Final report for research project sponsored by Northeast Utilities Service Company, Yankee Atomic Electric Co. under the MIT Energy Laboratory Electric Utility Program.
Evidence for Mass-dependent Circumstellar Disk Evolution in the 5 Myr Old Upper Scorpius OB Association
We present 4.5, 8, and 16 ”m photometry from the Spitzer Space Telescope for 204 stars in the Upper Scorpius OB
association. The data are used to investigate the frequency and properties of circumstellar disks around stars with masses between ~0.1 and 20 M_â at an age of ~5 Myr. We identify 35 stars that have emission at 8 or 16 ”m in excess of the, stellar photosphere. The lower mass stars (~0.1â1.2M_â) appear surrounded by primordial optically thick disks based on, the excess emission characteristics. Starsmoremassive than ~1.8M_â have lower fractional excess luminosities suggesting, that the inner ~10 AU of the disk has been largely depleted of primordial material. None of the G and F stars (~1.2â1.8 M_â) in our sample have an infrared excess at wavelengths â€16 ”m. These results indicate that the mechanisms for, dispersing primordial optically thick disks operate less efficiently, on average, for low-mass stars, and that longer timescales are available for the buildup of planetary systems in the terrestrial zone for stars with masses âŸ1 M_â
What are the prospects for privatizing infrastructure? Lessons from U. S. roads and solid waste
Infrastructure (Economics) ; Roads
Remote characterization of wetland vegetation and corresponding relationship to soils : final report on the evaluation of imagery-derived terrain attributes in the coastal zone
To accomplish the goals of this study, a pristine coastal barrier island environment was selected that was free from influences of urban development. This provided the optimal situation that could be expected to be encountered by military strategists and base resource managers. The site selected was Parramore Island (Figure I). Parramore Island is the seventh island ( north to south) located on the seaward margin of the southeastern Delmarva Peninsula and is one of the most dynamic and least disturbed coastal landscapes remaining in North America (McCaffrey and Dueser, 1990). The island is centered at Latitude 37° 30\u27 and Longitude 75° 40\u27 and is owned by the Nature Conservancy and managed as part of the Virginia Coast Reserve. The island is also included in the National Science Foundation\u27s Long Term Ecological Research Reserve System (LTER)
Radioactive Probes of the Supernova-Contaminated Solar Nebula: Evidence that the Sun was Born in a Cluster
We construct a simple model for radioisotopic enrichment of the protosolar
nebula by injection from a nearby supernova, based on the inverse square law
for ejecta dispersion. We find that the presolar radioisotopes abundances
(i.e., in solar masses) demand a nearby supernova: its distance can be no
larger than 66 times the size of the protosolar nebula, at a 90% confidence
level, assuming 1 solar mass of protosolar material. The relevant size of the
nebula depends on its state of evolution at the time of radioactivity
injection. In one scenario, a collection of low-mass stars, including our sun,
formed in a group or cluster with an intermediate- to high-mass star that ended
its life as a supernova while our sun was still a protostar, a starless core,
or perhaps a diffuse cloud. Using recent observations of protostars to estimate
the size of the protosolar nebula constrains the distance of the supernova at
0.02 to 1.6 pc. The supernova distance limit is consistent with the scales of
low-mass stars formation around one or more massive stars, but it is closer
than expected were the sun formed in an isolated, solitary state. Consequently,
if any presolar radioactivities originated via supernova injection, we must
conclude that our sun was a member of such a group or cluster that has since
dispersed, and thus that solar system formation should be understood in this
context. In addition, we show that the timescale from explosion to the creation
of small bodies was on the order of 1.8 Myr (formal 90% confidence range of 0
to 2.2 Myr), and thus the temporal choreography from supernova ejecta to
meteorites is important. Finally, we can not distinguish between progenitor
masses from 15 to 25 solar masses in the nucleosynthesis models; however, the
20 solar mass model is somewhat preferred.Comment: ApJ accepted, 19 pages, 3 figure
Boiling heat transfer for high velocity flow of highly subcooled water
"October 1998."Includes bibliographical references (p. 27-28
Graphical timeline editing
NASA's Experiment Scheduling Program (ESP), which has been used for approximately 12 Spacelab missions, is being enhanced with the addition of a Graphical Timeline Editor. The GTE Clipboard, as it is called, was developed to demonstrate new technology which will lead the development of International Space Station Alpha's Payload Planning System and support the remaining Spacelab missions. ESP's GTE Clipboard is developed in C using MIT's X Windows System X11R5 and follows OSF/Motif Style Guide Revision 1.2
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