3,644 research outputs found
Research and development of cells with bellows controlled electrolyte levels Final progress report, May 11, 1965 - Apr. 1, 1966
Control of electrolyte level in sealed Ni-Cd and Ag-Cd cells with bellows actio
The effects of human menstrual odors other scents and ringed seal vocalizations on the polar bear
On the net reproduction rate of continuous structured populations with distributed states at birth
We consider a nonlinear structured population model with a distributed
recruitment term. The question of the existence of non-trivial steady states
can be treated (at least!) in three different ways. One approach is to study
spectral properties of a parametrized family of unbounded operators. The
alternative approach, on which we focus here, is based on the reformulation of
the problem as an integral equation. In this context we introduce a density
dependent net reproduction rate and discuss its relationship to a biologically
meaningful quantity. Finally, we briefly discuss a third approach, which is
based on the finite rank approximation of the recruitment operator.Comment: To appear in Computers and Mathematics with Application
A Unified Theory for the Atmospheres of the Hot and Very Hot Jupiters: Two Classes of Irradiated Atmospheres
We highlight the importance of gaseous TiO and VO opacity on the highly
irradiated close-in giant planets. The atmospheres of these planets naturally
fall into two classes that are somewhat analogous to the M- and L-type dwarfs.
Those that are warm enough to have appreciable opacity due to TiO and VO gases
we term the ``pM Class'' planets, and those that are cooler we term ``pL
Class'' planets. We calculate model atmospheres for these planets, including
pressure-temperature profiles, spectra, and characteristic radiative time
constants. We show that pM Class planets have hot stratospheres 2000 K
and appear ``anomalously'' bright in the mid infrared secondary eclipse, as was
recently found for planets HD 149026b and HD 209458b. This class of planets
absorbs incident flux and emits thermal flux from high in their atmospheres.
Consequently, they will have large day/night temperature contrasts and
negligible phase shifts between orbital phase and thermal emission light
curves, because radiative timescales are much shorter than possible dynamical
timescales. The pL Class planets absorb incident flux deeper in the atmosphere
where atmospheric dynamics will more readily redistribute absorbed energy. This
will lead to cooler day sides, warmer night sides, and larger phase shifts in
thermal emission light curves. Around a Sun-like primary this boundary occurs
at 0.04-0.05 AU. The eccentric transiting planets HD 147506b and HD
17156b alternate between the classes. Thermal emission in the optical from pM
Class planets is significant red-ward of 400 nm, making these planets
attractive targets for optical detection. The difference in the observed
day/night contrast between ups Andromeda b (pM Class) and HD 189733b (pL Class)
is naturally explained in this scenario. (Abridged.)Comment: Accepted to the Astrophysical Journa
SDSS J141624.08+134826.7: Blue L Dwarfs and Non-Equilibrium Chemistry
We present an analysis of the recently discovered blue L dwarf SDSS
J141624.08+134826.7. We extend the spectral coverage of its published spectrum
to ~4 microns by obtaining a low-resolution L band spectrum with SpeX on the
NASA IRTF. The spectrum exhibits a tentative weak CH4 absorption feature at 3.3
microns but is otherwise featureless. We derive the atmospheric parameters of
SDSS J141624.08+134826.7 by comparing its 0.7-4.0 micron spectrum to the
atmospheric models of Marley and Saumon which include the effects of both
condensate cloud formation and non-equilibrium chemistry due to vertical mixing
and find the best fitting model has Teff=1700 K, log g=5.5 [cm s-2], fsed=4,
and Kzz=10^4 cm2 s-1. The derived effective temperature is significantly cooler
than previously estimated but we confirm the suggestion by Bowler et al. that
the peculiar spectrum of SDSS J141624.08+134826.7 is primarily a result of thin
condensate clouds. In addition, we find strong evidence of vertical mixing in
the atmosphere of SDSS J141624.08+134826.7 based on the absence of the deep 3.3
micron CH4 absorption band predicted by models computed in chemical
equilibrium. This result suggests that observations of blue L dwarfs are an
appealing way to quantitatively estimate the vigor of mixing in the atmospheres
of L dwarfs because of the dramatic impact such mixing has on the strength of
the 3.3 micron CH4 band in the emergent spectra of L dwarfs with thin
condensate clouds.Comment: Accepted for publication in the Astronomical Journa
Lifting Bell inequalities
A Bell inequality defined for a specific experimental configuration can always be extended to a situation involving more observers, measurement settings, or measurement outcomes. In this article, such "liftings" of Bell inequalities are studied. It is shown that if the original inequality defines a facet of the polytope of local joint outcome probabilities then the lifted one also defines a facet of the more complex polytope
New H2 collision-induced absorption and NH3 opacity and the spectra of the coolest brown dwarfs
We present new cloudy and cloudless model atmospheres for brown dwarfs using
recent ab initio calculations of the line list of ammonia (NH3) and of the
collision-induced absorption of molecular hydrogen (H2). We compare the new
synthetic spectra with models based on an earlier description of the H2 and NH3
opacities. We find a significant improvement in fitting the nearly complete
spectral energy distribution of the T7p dwarf Gliese 570D and in near infrared
color-magnitude diagrams of field brown dwarfs. We apply these new models to
the identification of NH3 absorption in the H band peak of very late T dwarfs
and the new Y dwarfs and discuss the observed trend in the NH3-H spectral
index. The new NH3 line list also allows a detailed study of the medium
resolution spectrum of the T9/T10 dwarf UGPS J072227.51-054031.2 where we
identify several specific features caused by NH3.Comment: 37 pages, 13 figures. Accepted for publication in the Astrophysical
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