5,649 research outputs found
The Observational Signatures of Primordial Pair-Instability Supernovae
Massive Population III stars from 140 - 260 solar masses ended their lives as
pair-instability supernovae (PISNe), the most energetic thermonuclear
explosions in the universe. Detection of these explosions could directly
constrain the primordial IMF for the first time, which is key to the formation
of the first galaxies, early cosmological reionization, and the chemical
enrichment of the primeval IGM. We present radiation hydrodynamical
calculations of Pop III PISN light curves and spectra performed with the RAGE
code. We find that the initial radiation pulse due to shock breakout from the
surface of the star, although attenuated by the Lyman-alpha forest, will still
be visible by JWST at z ~ 10 - 15, and possibly out to z ~ 20 with strong
gravitational lensing. We have also studied metal mixing at early stages of the
explosion prior to breakout from the surface of the star with the CASTRO AMR
code and find vigorous mixing in primordial core-collapse explosions but very
little in PISNe. This implies that the key to determining progenitor masses of
the first cosmic explosions is early spectroscopy just after shock breakout,
and that multidimensional mixing is crucial to accurate low-mass Pop III SNe
light curves and spectra.Comment: 4 pages, 3 figures, proceedings of Deciphering the Ancient Universe
with Gamma-Ray Bursts, Kyoto, Japan, April 19 - 23, 201
Miniature ingestible telemeter devices to measure deep-body temperature
A telemetry device comprised of a pill-size ingestible transmitter developed to obtain deep body temperature measurements of a human is described. The device has particular utility in the medical field where deep body temperatures provide an indication of general health
The Los Alamos Supernova Light Curve Project: Computational Methods
We have entered the era of explosive transient astronomy, in which upcoming
real-time surveys like the Large Synoptic Survey Telescope (LSST), the Palomar
Transient Factory (PTF) and Panoramic Survey Telescope and Rapid Response
System (Pan-STARRS) will detect supernovae in unprecedented numbers. Future
telescopes such as the James Webb Space Telescope may discover supernovae from
the earliest stars in the universe and reveal their masses. The observational
signatures of these astrophysical transients are the key to unveiling their
central engines, the environments in which they occur, and to what precision
they will pinpoint cosmic acceleration and the nature of dark energy. We
present a new method for modeling supernova light curves and spectra with the
radiation hydrodynamics code RAGE coupled with detailed monochromatic opacities
in the SPECTRUM code. We include a suite of tests that demonstrate how the
improved physics is indispensable to modeling shock breakout and light curves.Comment: 18 pages, 19 figures, published in ApJ Supplement
Soil microstructure and electron microscopy
As part of the process of comparing Martian soils with terrestial soils, high resolution electron microscopy and associated techniques should be used to examine the finer soil particles, and various techniques of electron and optical microscopy should be used to examine the undisturbed structure of Martian soils. To examine the structure of fine grained portions of the soil, transmission electron microscopy may be required. A striking feature of many Martian soils is their red color. Although the present-day Martian climate appears to be cold, this color is reminiscent of terrestial tropical red clays. Their chemical contents are broadly similar
Modeling Emission from the First Explosions: Pitfalls and Problems
Observations of the explosions of Population III (Pop III) stars have the
potential to teach us much about the formation and evolution of these
zero-metallicity objects. To realize this potential, we must tie observed
emission to an explosion model, which requires accurate light curve and spectra
calculations. Here, we discuss many of the pitfalls and problems involved in
such models, presenting some preliminary results from radiation-hydrodynamics
simulations.Comment: 6 pages, 3 figures, proceedings of 'The First Stars and Galaxies:
Challenges for the Next Decade", Austin, TX, March 8-11, 201
An ingestible temperature-transmitter
Pill-sized transmitter measures deep body temperature in studies of circadian rhythm and indicates general health. Ingestible device is a compromise between accuracy, circuit complexity, size and transmission range
Sharing Resources: Opportunities for Smaller Primary Care Practices to Increase Their Capacity for Patient Care
Outlines findings linking shared resources with use of health information technology, care coordination, self-management, and quality monitoring, and strategies to increase resources among small and midsize practices by expanding shared resource models
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