14,134 research outputs found
The equity premium puzzle and decreasing relative risk aversion
Agents are assumed to have a power risk aversion utility function in an otherwise standard asset pricing model. These preferences are shown to be capable of eliminating one version of the equity premium and risk free rate puzzles when they display decreasing relative risk aversion.asset pricing,equity premium,risk aversion
The Roche problem: some analytics
Some exact analytical formulas are derived for the potential and mass ratio
as a function of Lagrangian points position, in the classical Roche model of
the close binary stars.Comment: aastex, 4 pp. ApJ accepte
Solving the kilo-second QPO problem of the intermediate polar GK Persei
We detect the likely optical counterpart to previously reported X-ray QPOs in
spectrophotometry of the intermediate polar GK Persei during the 1996 dwarf
nova outburst. The characteristic timescales range between 4000--6000 s.
Although the QPOs are an order of magnitude longer than those detected in the
other dwarf novae we show that a new QPO model is not required to explain the
long timescale observed. We demonstrate that the observations are consistent
with oscillations being the result of normal-timescale QPOs beating with the
spin period of the white dwarf. We determine the spectral class of the
companion to be consistent with its quiescent classification and find no
significant evidence for irradiation over its inner face. We detect the white
dwarf spin period in line fluxes, V/R ratios and Doppler-broadened emission
profiles.Comment: 14 pages, 11 figures. Accepted for publication in MNRA
Phase space polarization and the topological string: a case study
We review and elaborate on our discussion in hep-th/0606112 on the interplay
between the target space and the worldsheet description of the open topological
string partition function, for the example of the conifold. We discuss the
appropriate phase space and canonical form for the system. We find a map
between choices of polarization and the worldsheet description, based on which
we study the behavior of the partition function under canonical
transformations.Comment: 18 pages, invited review for MPL
The Be/X-ray Transient V0332+53: Evidence for a tilt between the orbit and the equatorial plane?
We present optical and infrared observations of BQ Cam, the optical
counterpart to the Be/X-ray transient system V0332+53. BQ Cam is shown to be an
O8-9Ve star, which places V0332+53 at a distance of ~7 kpc. H-alpha
spectroscopy and infrared photometry are used to discuss the evolution of the
circumstellar envelope. Due to the low inclination of the system, parameters
are strongly constrained. We find strong evidence for a tilt of the orbital
plane with respect to the circumstellar disc (pressumably on the equatorial
plane). Even though the periastron distance is only ~ 10 R_*, during the
present quiescent state the circumstellar disc does not extend to the distance
of periastron passage. Under these conditions, X-ray emission is effectively
prevented by centrifugal inhibition of accretion. The circumstellar disc is
shown to be optically dense at optical and infrared wavelengths, which together
with its small size, is taken as an indication of tidal truncation.Comment: 9 pages, 3 figures, uses mn.sty and epsfig Accepted for publication
in MNRA
Assessing the clinical value of fast onset and sustained duration of action of long-acting bronchodilators for COPD
Date of Aceptance: 12/02/2015 Acknowledgments The authors were assisted in the preparation of the manuscript by Sarah Filcek, a professional medical writer at CircleScience (Tytherington, UK), part of KnowledgePoint360, an Ashfield Company. This assistance was funded by Novartis Pharmaceuticals. Copyright © 2015. Published by Elsevier Ltd.Peer reviewedPublisher PD
Near-infrared and Millimeter Constraints on the Nuclear Energy Source of the Infrared Luminous Galaxy NGC 4418
We present near-infrared and millimeter investigations of the nucleus of the
infrared luminous galaxy NGC 4418, which previous observations suggest
possesses a powerful buried AGN. We found the following main results: (1) The
infrared K-band spectrum shows CO absorption features at 2.3-2.4 micron owing
to stars and very strong H2 emission lines. The luminosity ratios of H2
emission lines are suggestive of a thermal origin, and the equivalent width of
the H2 1-0 S(1) line is the second largest observed to date in an external
galaxy, after the well-studied strong H2-emitting galaxy NGC 6240. (2) The
infrared L-band spectrum shows a clear polycyclic aromatic hydrocarbon (PAH)
emission feature at 3.3 micron, which is usually found in star-forming
galaxies. The estimated star-formation luminosity from the observed PAH
emission can account for only a small fraction of the infrared luminosity. (3)
Millimeter interferometric observations of the nucleus reveal a high HCN (1-0)
to HCO+ (1-0) luminosity ratio of 1.8, as has been previously found in pure
AGNs. (4) The measurements of HCN (1-0) luminosity using a single-dish
millimeter telescope show that the HCN (1-0) to infrared luminosity ratio is
slightly larger than the average, but within the scattered range, for other
infrared luminous galaxies. All of these results can be explained by the
scenario in which, in addition to energetically-insignificant, weakly-obscured
star-formation at the surface of the nucleus, a powerful X-ray emitting AGN
deeply buried in dust and high density molecular gas is present.Comment: 31 pages, 9 figures, Accepted for publication in Astronomical Journal
(2004 November issue
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