3,069 research outputs found
The Affective Impact of Financial Skewness on Neural Activity and Choice
Few finance theories consider the influence of âskewnessâ (or large and asymmetric but unlikely outcomes) on financial choice. We investigated the impact of skewed gambles on subjects' neural activity, self-reported affective responses, and subsequent preferences using functional magnetic resonance imaging (FMRI). Neurally, skewed gambles elicited more anterior insula activation than symmetric gambles equated for expected value and variance, and positively skewed gambles also specifically elicited more nucleus accumbens (NAcc) activation than negatively skewed gambles. Affectively, positively skewed gambles elicited more positive arousal and negatively skewed gambles elicited more negative arousal than symmetric gambles equated for expected value and variance. Subjects also preferred positively skewed gambles more, but negatively skewed gambles less than symmetric gambles of equal expected value. Individual differences in both NAcc activity and positive arousal predicted preferences for positively skewed gambles. These findings support an anticipatory affect account in which statistical properties of gamblesâincluding skewnessâcan influence neural activity, affective responses, and ultimately, choice
The Orbit of WASP-12b Is Decaying
WASP-12b is a transiting hot Jupiter on a 1.09 day orbit around a late-F star. Since the planet's discovery in 2008, the time interval between transits has been decreasing by 29 ± 2 ms yrâ»Âč. This is a possible sign of orbital decay, although the previously available data left open the possibility that the planet's orbit is slightly eccentric and is undergoing apsidal precession. Here, we present new transit and occultation observations that provide more decisive evidence for orbital decay, which is favored over apsidal precession by a ÎBIC of 22.3 or Bayes factor of 70,000. We also present new radial-velocity data that rule out the RĂžmer effect as the cause of the period change. This makes WASP-12 the first planetary system for which we can be confident that the orbit is decaying. The decay timescale for the orbit is P/PË=3.25±0.23. Interpreting the decay as the result of tidal dissipation, the modified stellar tidal quality factor is QâČâ=1.8Ă10â”
Ground- and Space-based Detection of the Thermal Emission Spectrum of the Transiting Hot Jupiter KELT-2Ab
We describe the detection of water vapor in the atmosphere of the transiting
hot Jupiter KELT-2Ab by treating the star-planet system as a spectroscopic
binary with high-resolution, ground-based spectroscopy. We resolve the signal
of the planet's motion with deep combined flux observations of the star and the
planet. In total, six epochs of Keck NIRSPEC -band observations were
obtained, and the full data set was subjected to a cross correlation analysis
with a grid of self-consistent atmospheric models. We measure a radial
projection of the Keplerian velocity, , of 148 7 km s,
consistent with transit measurements, and detect water vapor at 3.8. We
combine NIRSPEC -band data with IRAC secondary eclipse data to
further probe the metallicity and carbon-to-oxygen ratio of KELT-2Ab's
atmosphere. While the NIRSPEC analysis provides few extra constraints on the
data, it does provide roughly the same constraints on metallicity and
carbon-to-oxygen ratio. This bodes well for future investigations of the
atmospheres of non-transiting hot Jupiters.Comment: accepted to A
Off-shell Behavior of the Mixing Amplitude
We extend a recent calculation of the momentum dependence of the
mixing amplitude to the pseudoscalar sector. The
mixing amplitude is calculated in a hadronic model where the mixing is driven
by the neutron-proton mass difference. Closed-form analytic expressions are
presented in terms of a few nucleon-meson parameters. The observed momentum
dependence of the mixing amplitude is strong enough as to question earlier
calculations of charge-symmetry-breaking observables based on the on-shell
assumption. The momentum dependence of the amplitude is,
however, practically identical to the one recently predicted for
mixing. Hence, in this model, the ratio of pseudoscalar to vector mixing
amplitudes is, to a good approximation, a constant solely determined from
nucleon-meson coupling constants. Furthermore, by selecting these parameters in
accordance with charge-symmetry-conserving data and SU(3)-flavor symmetry, we
reproduce the momentum dependence of the mixing amplitude
predicted from chiral perturbation theory. Alternatively, one can use
chiral-perturbation-theory results to set stringent limits on the value of the
coupling constant.Comment: 13 pages, Latex with Revtex, 3 postscript figures (not included)
available on request, SCRI-03089
Thermal Emission of WASP-14b Revealed with Three Spitzer Eclipses
Exoplanet WASP-14b is a highly irradiated, transiting hot Jupiter. Joshi et
al. calculate an equilibrium temperature Teq of 1866 K for zero albedo and
reemission from the entire planet, a mass of 7.3 +/- 0.5 Jupiter masses and a
radius of 1.28 +/- 0.08 Jupiter radii. Its mean density of 4.6 g/cm3 is one of
the highest known for planets with periods less than 3 days. We obtained three
secondary eclipse light curves with the Spitzer Space Telescope. The eclipse
depths from the best jointly fit model are +/- at 4.5
{\mu}m and +/- at 8.0 {\mu}m. The corresponding brightness
temperatures are 2212 +/- 94 K and 1590 +/- 116 K. A slight ambiguity between
systematic models suggests a conservative 3.6 {\mu}m eclipse depth of
+/- and brightness temperature of 2242 +/- 55 K. Although extremely
irradiated, WASP-14b does not show any distinct evidence of a thermal
inversion. In addition, the present data nominally favor models with day night
energy redistribution less than . The current data are generally
consistent with oxygen-rich as well as carbon-rich compositions, although an
oxygen-rich composition provides a marginally better fit. We confirm a
significant eccentricity of e = 0.087 +/- 0.002 and refine other orbital
parameters.Comment: 16 pages, 16 figure
Refined parameters of the planet orbiting HD 189733
We report on the BVRI multi-band follow-up photometry of the transiting
extrasolar planet HD 189733b. We revise the transit parameters and find
planetary radius RP = 1.154+/- 0.032RJ and inclination i_P = 85.79+/-0.24deg.
The new density (~ 1g cm-3) is significantly higher than the former estimate (~
0.75g cm-3); this shows that from the current sample of 9 transiting planets,
only HD 209458 (and possibly OGLE-10b) have anomalously large radii and low
densities. We note that due to the proximity of the parent star, HD 189733b
currently has one of the most precise radius determinations among extrasolar
planets. We calculate new ephemerides: P = 2.218573+/-0.000020 days, T0 =
2453629.39420+/-0.00024 (HJD), and estimate the timing offsets of the 11
distinct transits with respect to the predictions of a constant orbital period,
which can be used to reveal the presence of additional planets in the system.Comment: 10 pages, 4 figures, submitted to Ap
Paper Session I-A - Planning for the Performance of Future Space Bases
The United States Air Force and the Department of Defense are moving toward normalizing space operations, from specialized one-of-a-kind launch to standardized launch, much as they provide airlift today. Normalized launch will enhance our capability to meet contingency operations responsive to the rapidly changing world geopolitical situation. The current space infrastructure will not fully support future launch operation concepts. We must be more sensitive to environmental concerns, and improved performance standards are needed for future space facilities* The Air Force is taking the lead in bringing together the worldwide space community in developing a process for performance planning of future space bases
The Off Shell - Mixing in the QCD Sum Rules
The dependence of the mixing amplitude is analyzed with
the use of the QCD sum rules and the dispersion relation. Going off shell the
mixing decreases, changes sign at and is
negative in the space like region. Implications of this result to the isospin
breaking part of the nuclear force are discussed.Comment: 26 pages + 11 figures (PostScript
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