5,662 research outputs found
History of Black Quarterbacks in the NFL
The current paper discusses the evolution of African-American football players, specifically those at the Quarterback position. Moreover, it describes the initial lack of diversity on the field driven by a number of external factors. I will look to analyze the cause to this unbalance and determine whether or not the historical stereotypes labeled on black men and faulty media coverage has factored into the decisions of owners, coaches, and scouts regarding the quarterback position
The use of field-programmable gate arrays for the hardware acceleration of design automation tasks
This paper investigates the possibility of using Field-Programmable Gate Arrays (FrâGAS) as
reconfigurable co-processors for workstations to produce moderate speedups for most tasks
in the design process, resulting in a worthwhile overall design process speedup at low cost
and allowing algorithm upgrades with no hardware modification. The use of FPGAS as hardware
accelerators is reviewed and then achievable speedups are predicted for logic simulation
and VLSI design rule checking tasks for various FPGA co-processor arrangements
Discovery and Atmospheric Characterization of Giant Planet Kepler-12b: An Inflated Radius Outlier
We report the discovery of planet Kepler-12b (KOI-20), which at 1.695 ± 0.030 R_J is among the handful of planets with super-inflated radii above 1.65 R_J. Orbiting its slightly evolved G0 host with a 4.438 day period, this 0.431 ± 0.041 M_J planet is the least irradiated within this largest-planet-radius group, which has important implications for planetary physics. The planet's inflated radius and low mass lead to a very low density of 0.111 ± 0.010 g cm^(â3). We detect the occultation of the planet at a significance of 3.7Ï in the Kepler bandpass. This yields a geometric albedo of 0.14 ± 0.04; the planetary flux is due to a combination of scattered light and emitted thermal flux. We use multiple observations with Warm Spitzer to detect the occultation at 7Ï and 4Ï in the 3.6 and 4.5 ÎŒm bandpasses, respectively. The occultation photometry timing is consistent with a circular orbit at e < 0.01 (1Ï) and e < 0.09 (3Ï). The occultation detections across the three bands favor an atmospheric model with no dayside temperature inversion. The Kepler occultation detection provides significant leverage, but conclusions regarding temperature structure are preliminary, given our ignorance of opacity sources at optical wavelengths in hot Jupiter atmospheres. If Kepler-12b and HD 209458b, which intercept similar incident stellar fluxes, have the same heavy-element masses, the interior energy source needed to explain the large radius of Kepler-12b is three times larger than that of HD 209458b. This may suggest that more than one radius-inflation mechanism is at work for Kepler-12b or that it is less heavy-element rich than other transiting planets
Projections from Subvarieties
Let be an n-dimensional connected projective submanifold of
projective space. Let denote the projection from a
linear . Assuming that we have the induced
rational mapping . This article started as an
attempt to understand the structure of this mapping when has a lower
dimensional image. In this case of necessity we have is
nonempty. We have in this article studied a closely related question, which
includes many special cases including the case when the center of the
projection \pn q is contained in .
PROBLEM. Let be a proper connected k-dimensional projective submanifold
of an -dimensional projective manifold . Assume that . Let be a
very ample line bundle on such that is spanned by global
sections, where denotes the ideal sheaf of in . Describe the
structure of under the additional assumption that the image of
under the mapping associated to is lower dimensional
Newly-Discovered Planets Orbiting HD~5319, HD~11506, HD~75784 and HD~10442 from the N2K Consortium
Initially designed to discover short-period planets, the N2K campaign has
since evolved to discover new worlds at large separations from their host
stars. Detecting such worlds will help determine the giant planet occurrence at
semi-major axes beyond the ice line, where gas giants are thought to mostly
form. Here we report four newly-discovered gas giant planets (with minimum
masses ranging from 0.4 to 2.1 MJup) orbiting stars monitored as part of the
N2K program. Two of these planets orbit stars already known to host planets: HD
5319 and HD 11506. The remaining discoveries reside in previously-unknown
planetary systems: HD 10442 and HD 75784. The refined orbital period of the
inner planet orbiting HD 5319 is 641 days. The newly-discovered outer planet
orbits in 886 days. The large masses combined with the proximity to a 4:3 mean
motion resonance make this system a challenge to explain with current formation
and migration theories. HD 11506 has one confirmed planet, and here we confirm
a second. The outer planet has an orbital period of 1627.5 days, and the
newly-discovered inner planet orbits in 223.6 days. A planet has also been
discovered orbiting HD 75784 with an orbital period of 341.7 days. There is
evidence for a longer period signal; however, several more years of
observations are needed to put tight constraints on the Keplerian parameters
for the outer planet. Lastly, an additional planet has been detected orbiting
HD 10442 with a period of 1043 days.Comment: Accepted for publication in Ap
Loose Ends for the Exomoon Candidate Host Kepler-1625b
The claim of an exomoon candidate in the Kepler-1625b system has generated
substantial discussion regarding possible alternative explanations for the
purported signal. In this work we examine in detail these possibilities. First,
the effect of more flexible trend models is explored and we show that
sufficiently flexible models are capable of attenuating the signal, although
this is an expected byproduct of invoking such models. We also explore trend
models using X and Y centroid positions and show that there is no data-driven
impetus to adopt such models over temporal ones. We quantify the probability
that the 500 ppm moon-like dip could be caused by a Neptune-sized transiting
planet to be < 0.75%. We show that neither autocorrelation, Gaussian processes
nor a Lomb-Scargle periodogram are able to recover a stellar rotation period,
demonstrating that K1625 is a quiet star with periodic behavior < 200 ppm.
Through injection and recovery tests, we find that the star does not exhibit a
tendency to introduce false-positive dip-like features above that of pure
Gaussian noise. Finally, we address a recent re-analysis by Kreidberg et al
(2019) and show that the difference in conclusions is not from differing
systematics models but rather the reduction itself. We show that their
reduction exhibits i) slightly higher intra-orbit and post-fit residual
scatter, ii) 900 ppm larger flux offset at the visit change, iii)
2 times larger Y-centroid variations, and iv) 3.5 times
stronger flux-centroid correlation coefficient than the original analysis.
These points could be explained by larger systematics in their reduction,
potentially impacting their conclusions.Comment: 21 pages, 4 tables, 11 figures. Accepted for publication in The
Astronomical Journal, January 202
Warm Ice Giant GJ 3470b. I. A Flat Transmission Spectrum Indicates a Hazy, Low-methane, and/or Metal-rich Atmosphere
We report our spectroscopic investigation of the transiting ice giant GJ
3470b's atmospheric transmission, and the first results of extrasolar planet
observations from the new Keck/MOSFIRE spectrograph. We measure a planet/star
radius ratio of Rp/Rs = 0.0789 +/- 0.0020 in a bandpass from 2.09-2.36 micron
and in six narrower bands across this wavelength range. When combined with
existing broadband photometry, these measurements rule out cloud-free
atmospheres in chemical equilibrium assuming either solar abundances (5.4 sigma
confidence) or a moderate level of metal enrichment (50x solar abundances, 3.8
sigma), confirming previous results that such models are not representative for
cool, low-mass, externally irradiated extrasolar planets. Current measurements
are consistent with a flat transmission spectrum, which suggests that the
atmosphere is explained by high-altitude clouds and haze, disequilibrium
chemistry, unexpected abundance patterns, or the atmosphere is extremely
metal-rich (>200x solar). Because GJ 3470b's low bulk density sets an upper
limit on the planet's atmospheric enrichment of <300x solar, the atmospheric
mean molecular weight must be <9. Thus, if the atmosphere is cloud-free its
spectral features should be detectable with future observations. Transit
observations at shorter wavelengths will provide the best opportunity to
discriminate between plausible scenarios. We obtained optical spectroscopy with
the GMOS spectrograph, but these observations exhibit large systematic
uncertainties owing to thin, persistent cirrus conditions. Finally, we also
provide the first detailed look at the steps necessary for well-calibrated
MOSFIRE observations, and provide advice for future observations with this
instrument.Comment: Accepted to A&A. Light curves will be available at CDS (or download
arXiv tarball
K2-231 b: A sub-Neptune exoplanet transiting a solar twin in Ruprecht 147
We identify a sub-Neptune exoplanet ( R)
transiting a solar twin in the Ruprecht 147 star cluster (3 Gyr, 300 pc, [Fe/H]
= +0.1 dex). The ~81 day light curve for EPIC 219800881 (V = 12.71) from K2
Campaign 7 shows six transits with a period of 13.84 days, a depth of ~0.06%,
and a duration of ~4 hours. Based on our analysis of high-resolution MIKE
spectra, broadband optical and NIR photometry, the cluster parallax and
interstellar reddening, and isochrone models from PARSEC, Dartmouth, and MIST,
we estimate the following properties for the host star: M, R, and K. This star appears to be single, based on our modeling of the
photometry, the low radial velocity variability measured over nearly ten years,
and Keck/NIRC2 adaptive optics imaging and aperture-masking interferometry.
Applying a probabilistic mass-radius relation, we estimate that the mass of
this planet is M, which would cause a RV
semi-amplitude of m s that may be measurable with existing
precise RV facilities. After statistically validating this planet with BLENDER,
we now designate it K2-231 b, making it the second sub-stellar object to be
discovered in Ruprecht 147 and the first planet; it joins the small but growing
ranks of 23 other planets found in open clusters.Comment: 24 pages, 7 figures, light curve included as separate fil
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