16,326 research outputs found
Proto-Brown Dwarf Disks as Products of Protostellar Disk Encounters
The formation of brown dwarfs via encounters between proto-stars has been
confirmed with high-resolution numerical simulations with a restricted
treatment of the thermal conditions. The new results indicate that young brown
dwarfs (BDs) formed this way are disk-like and often reside in multiple
systems. The newly-formed proto-BDs disks are up to 18 AU in size and spin
rapidly making small-scale bipolar outflows, fragmentation and the possible
formation of planetary companions likely as have recently been observed for
BDs. The object masses range from 2 to 73 Jupiter masses, distributed in a
manner consistent with the observed sub-stellar initial mass function. The
simulations usually form multiple BDs on eccentric orbits about a star. One
such system was hierarchical, a BD binary in orbit around a star, which may
explain recently observed hierarchical systems. One third of the BDs were
unbound after a few thousand years and interactions among orbiting BDs may
eject more or add to the number of binaries. Improvements over prior work
include resolution down to a Jupiter mass, self-consistent models of the
vertical structure of the initial disks and careful attention to avoid
artificial fragmentation.Comment: 4 pages, 3 figures, accepted for publication in ApJ Letter
New research on bioregenerative air/water purification systems
For the past several years, air and water purification systems have been developed and used. This technology is based on the combined activities of plants and microorganisms as they function in a natural environment. More recently, researchers have begun to address the problems associated with indoor air pollution. Various common houseplants are currently being evaluated for their abilities to reduce concentrations of volatile organic compounds (VOCS) such as formaldehyde and benzene. With development of the Space Exploration Initiative, missions will increase in duration, and problems with resupply necessitates implementation of regenerative technology. Aspects of bioregenerative technology have been included in a habitat known as the BioHome. The ultimate goal is to use this technology in conjunction with physicochemical systems for air and water purification within closed systems. This study continued the risk assessment of bioregenerative technology with emphasis on biological hazards. In an effort to evaluate the risk for human infection, analyses were directed at enumeration of fecal streptococci and enteric viruses with the BioHome waste water treatment system
Personalized medicine : the impact on chemistry
An effective strategy for personalized medicine requires a major conceptual change in the development and application of therapeutics. In this article, we argue that further advances in this field should be made with reference to another conceptual shift, that of network pharmacology. We examine the intersection of personalized medicine and network pharmacology to identify strategies for the development of personalized therapies that are fully informed by network pharmacology concepts. This provides a framework for discussion of the impact personalized medicine will have on chemistry in terms of drug discovery, formulation and delivery, the adaptations and changes in ideology required and the contribution chemistry is already making. New ways of conceptualizing chemistryâs relationship with medicine will lead to new approaches to drug discovery and hold promise of delivering safer and more effective therapies
Study of guidance techniques for aerial application of agricultural compounds
Candidate systems were identified for evaluation of suitability in meeting specified accuracy requirements for a swath guidance system in an agriculture aircraft. Further examination reduced the list of potential candidates to a single category, i.e., transponder type systems, for detailed evaluation. Within this category three systems were found which met the basic accuracy requirements of the work statement. The Flying Flagman, the Electronic Flagging and the Raydist Director System. In addition to evaluating the systems against the specified requirements, each system was compared with the other two systems on a relative basis. The conclusions supported by the analyses show the Flying Flagman system to be the most suitable system currently available to meet the requirements
Flows on scales of 150 Mpc?
We investigate the reality of large-scale streaming on scales of up to 150
Mpc using the peculiar motions of galaxies in three directions. New R-band CCD
photometry and spectroscopy for elliptical galaxies is used. The Fundamental
Plane distance indicator is calibrated using the Coma cluster and an
inhomogeneous Malmquist bias correction is applied. A linear bulk-flow model is
fitted to the peculiar velocities in the sample regions and the results do not
reflect the bulk flow observed by Lauer and Postman (LP). Accounting for the
difference in geometry between the galaxy distribution in the three regions and
the LP clustersconfirms the disagreement; assuming a low-density CDM power
spectrum, we find that the observed bulk flow of the galaxies in our sample
excludes the LP bulk flow at the 99.8% confidence level.Comment: 16 pages, 1 figur
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