3,973 research outputs found
Possible Observational Criteria for Distinguishing Brown Dwarfs from Planets
The difference in formation process between binary stars and planetary
systems is reflected in their composition as well as their orbital
architecture, particularly orbital eccentricity as a function of orbital
period. It is suggested here that this difference can be used as an
observational criterion to distinguish between brown dwarfs and planets.
Application of the orbital criterion suggests that with three possible
exceptions, all of the recently-discovered substellar companions discovered to
date may be brown dwarfs and not planets. These criterion may be used as a
guide for interpretation of the nature of sub-stellar mass companions to stars
in the future.Comment: LaTeX, 11 pages including 2 figures, accepted for publication in the
Astrophysical Journal Letter
Planetary astronomy
The authors profile the field of astronomy, identify some of the key scientific questions that can be addressed during the decade of the 1990's, and recommend several facilities that are critically important for answering these questions. Scientific opportunities for the 1990' are discussed. Areas discussed include protoplanetary disks, an inventory of the solar system, primitive material in the solar system, the dynamics of planetary atmospheres, planetary rings and ring dynamics, the composition and structure of the atmospheres of giant planets, the volcanoes of IO, and the mineralogy of the Martian surface. Critical technology developments, proposed projects and facilities, and recommendations for research and facilities are discussed
Human Periodontal Fibroblast Response to Enamel Matrix Derivative, Amelogenin, and PlateletâDerived Growth FactorâBB
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142271/1/jper1242.pd
The Composition of Comets
This paper is the result of the International Cometary Workshop, held in
Toulouse, France in April 2014, where the participants came together to assess
our knowledge of comets prior to the ESA Rosetta Mission. In this paper, we
look at the composition of the gas and dust from the comae of comets. With the
gas, we cover the various taxonomic studies that have broken comets into groups
and compare what is seen at all wavelengths. We also discuss what has been
learned from mass spectrometers during flybys. A few caveats for our
interpretation are discussed. With dust, much of our information comes from
flybys. They include {\it in situ} analyses as well as samples returned to
Earth for laboratory measurements. Remote sensing IR observations and
polarimetry are also discussed. For both gas and dust, we discuss what
instruments the Rosetta spacecraft and Philae lander will bring to bear to
improve our understanding of comet 67P/Churyumov-Gerasimenko as "ground-truth"
for our previous comprehensive studies. Finally, we summarize some of the
initial Rosetta Mission findings.Comment: To appear in Space Science Review
Recommended from our members
Kepler-4B: A Hot Neptune-Like Planet of A G0 Star Near Main-Sequence Turnoff
Early time-series photometry from NASA's Kepler spacecraft has revealed a planet transiting the star we term Kepler-4, at R.A. = 19(h)02(m)27.(s)68, delta = +50 degrees 08'08 '' 7. The planet has an orbital period of 3.213 days and shows transits with a relative depth of 0.87 x 10(-3) and a duration of about 3.95 hr. Radial velocity (RV) measurements from the Keck High Resolution Echelle Spectrometer show a reflex Doppler signal of 9.3(-1.9)(+1.1) m s(-1), consistent with a low-eccentricity orbit with the phase expected from the transits. Various tests show no evidence for any companion star near enough to affect the light curve or the RVs for this system. From a transit-based estimate of the host star's mean density, combined with analysis of high-resolution spectra, we infer that the host star is near turnoff from the main sequence, with estimated mass and radius of 1.223(-0.091)(+0.053) M(circle dot) and 1.487(-0.084)(+0.071) R(circle dot).We estimate the planet mass and radius to be {M(P), R(P)} = {24.5 +/- 3.8 M(circle plus), 3.99 +/- 0.21 R(circle plus)}. The planet's density is near 1.9 g cm(-3); it is thus slightly denser and more massive than Neptune, but about the same size.W. M. Keck FoundationNASA's Science Mission DirectorateAstronom
Kepler Observations of Transiting Hot Compact Objects
Kepler photometry has revealed two unusual transiting companions orbiting an
early A-star and a late B-star. In both cases the occultation of the companion
is deeper than the transit. The occultation and transit with follow-up optical
spectroscopy reveal a 9400 K early A-star, KOI-74 (KIC 6889235), with a
companion in a 5.2 day orbit with a radius of 0.08 Rsun and a 10000 K late
B-star KOI-81 (KIC 8823868) that has a companion in a 24 day orbit with a
radius of 0.2 Rsun. We infer a temperature of 12250 K for KOI-74b and 13500 K
for KOI-81b.
We present 43 days of high duty cycle, 30 minute cadence photometry, with
models demonstrating the intriguing properties of these object, and speculate
on their nature.Comment: 12 pages, 3 figures, submitted to ApJL (updated to correct KOI74
lightcurve
Living Cellular Construct for Increasing the Width of Keratinized Gingiva: Results From a Randomized, WithinâPatient, Controlled Trial
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142206/1/jper1414.pd
Breast cancer in lesbians and bisexual women: Systematic review of incidence, prevalence and risk studies
This article is made available through the Brunel Open Access Publishing Fund. © 2013 Meads and Moore; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the
Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.Background: The UK Parliamentary Enquiry and USA Institute of Medicine state that lesbians may be at a higher risk of breast cancer but there is insufficient information. Lesbians and bisexual (LB) women have behavioural risk-factors at higher rates compared to heterosexuals such as increased alcohol intake and higher stress levels. Conversely, breast cancer rates are higher in more affluent women yet income levels in LB women are relatively low. This systematic review investigated all evidence on whether there is, or likely to be, higher rates of breast cancer in LB women. Methods: Cochrane library (CDSR, CENTRAL, HTA, DARE, NHSEED), MEDLINE, EMBASE, PsychINFO, CAB abstracts, Web of Science (SCI, SSCI), SIGLE and Social Care Online databases were searched to October 2013. Unpublished research and specific lesbian, gay and bisexual websites were checked, as were citation lists of relevant papers. Included were studies in LB populations reporting breast cancer incidence or prevalence rates, risk model results or risk-factor estimates. Inclusions, data-extraction and quality assessment were by two reviewers with disagreements resolved by discussion. Results: Searches found 198 references. No incidence rates were found. Nine studies gave prevalence estimates - two showed higher, four showed no differences, one showed mixed results depending on definitions, one had no comparison group and one gave no sample size. All studies were small with poor methodological and/or reporting quality. One incidence modelling study suggested a higher rate. Four risk modelling studies were found, one Rosner-Colditz and three Gail models. Three suggested higher and one lower rate in LB compared to heterosexual women. Six risk-factor estimates suggested higher risk and one no difference between LB and heterosexual women. Conclusions: The only realistic way to establish rates in LB women would be to collect sexual orientation within routine statistics, including cancer registry data, or from large cohort studies
Discovery of the Transiting Planet Kepler-5B
We present 44 days of high duty cycle, ultra precise photometry of the 13th magnitude star Kepler-5 (KIC 8191672, T(eff) = 6300 K, log g = 4.1), which exhibits periodic transits with a depth of 0.7%. Detailed modeling of the transit is consistent with a planetary companion with an orbital period of 3.548460 +/- 0.000032 days and a radius of 1.431(-0.052)(+0.041) R(J). Follow-up radial velocity measurements with the Keck HIRES spectrograph on nine separate nights demonstrate that the planet is more than twice as massive as Jupiter with a mass of 2.114(-0.059)(+0.056) M(J) and a mean density of 0.894 +/- 0.079 g cm(-3).NASA's Science Mission DirectorateAstronom
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