3,722 research outputs found
Dual formulation of the utility maximization problem: the case of nonsmooth utility
We study the dual formulation of the utility maximization problem in
incomplete markets when the utility function is finitely valued on the whole
real line. We extend the existing results in this literature in two directions.
First, we allow for nonsmooth utility functions, so as to include the
shortfall minimization problems in our framework. Second, we allow for the
presence of some given liability or a random endowment. In particular, these
results provide a dual formulation of the utility indifference valuation rule
Deepest Near-IR Surface Photometry of Galaxies in the Local Sphere of Influence
We present near-IR, deep (4 mag deeper than 2MASS) imaging of 56 Local Volume
galaxies. Global parameters such as total magnitudes and stellar masses have
been derived and the new near-IR data combined with existing 21cm and optical
B-band data. We present multiwavelength relations such as the HI mass-to-light
ratio and investigate the maximum total baryonic mass a galaxy can have.Comment: 4 pages, 3 figures, To be published in the proceedings of "Galaxies
in the Local Volume", ed. B. Koribalski, H. Jerje
Nuclear-spin relaxation of Pb in ferroelectric powders
Motivated by a recent proposal by O. P. Sushkov and co-workers to search for
a P,T-violating Schiff moment of the Pb nucleus in a ferroelectric
solid, we have carried out a high-field nuclear magnetic resonance study of the
longitudinal and transverse spin relaxation of the lead nuclei from room
temperature down to 10 K for powder samples of lead titanate (PT), lead
zirconium titanate (PZT), and a PT monocrystal. For all powder samples and
independently of temperature, transverse relaxation times were found to be
ms, while the longitudinal relaxation times exhibited a
temperature dependence, with of over an hour at the lowest temperatures,
decreasing to s at room temperature. At high temperatures, the
observed behavior is consistent with a two-phonon Raman process, while in the
low temperature limit, the relaxation appears to be dominated by a
single-phonon (direct) process involving magnetic impurities. This is the first
study of temperature-dependent nuclear-spin relaxation in PT and PZT
ferroelectrics at such low temperatures. We discuss the implications of the
results for the Schiff-moment search.Comment: 6 pages, 4 figure
Quantified Morphology of HI Disks in the Universe
he upcoming new perspective of the high redshift Universe in the 21 cm line
of atomic hydrogen opens possibilities to explore topics of spiral disk
evolution, hitherto reserved for the optical regime. The growth of spiral gas
disks over Cosmic time can be explored with the new generation of radio
telescopes, notably the SKA, and its precursors, as accurately as with the
Hubble Space Telescope for stellar disks. Since the atomic hydrogen gas is the
building block of these disks, it should trace their formation accurately.
Morphology of HI disks can now equally be quantified over Cosmic time. In
studies of HST deep fields, the optical or UV morphology of high-redshift
galaxy disks have been characterized using a few quantities: concentration (C),
asymmetry (A), smoothness (S), second-order-moment (M20), the GINI coefficient
(G), and Ellipticity (E). We have applied these parameters across wavelengths
and compared them to the HI morphology over the THINGS sample. NGC 3184, an
unperturbed disk, and NGC 5194, the canonical 3:1 interaction, serve as
examples for quantified morphology. We find that morphology parameters
determined in HI are as good or better a tracer of interaction compared to
those in any other wavelength, notably in Asymmetry, Gini and M20. This opens
the possibility of using them in the parameterization pipeline for SKA
precursor catalogues to select interacting or harassed galaxies from their HI
morphology. Asymmetry, Gini and M20 may be redefined for use on data-cubes
rather than HI column density image.Comment: 6 pages, 3 figures, proceeding of the conference "Panoramic Radio
Astronomy: Wide-field 1-2 GHz research on galaxy evolution", June 02 - 05
2009, Groningen, update after small edit
Bidding process in online auctions and winning strategy:rate equation approach
Online auctions have expanded rapidly over the last decade and have become a
fascinating new type of business or commercial transaction in this digital era.
Here we introduce a master equation for the bidding process that takes place in
online auctions. We find that the number of distinct bidders who bid times,
called the -frequent bidder, up to the -th bidding progresses as
. The successfully transmitted bidding rate by the
-frequent bidder is obtained as , independent of
for large . This theoretical prediction is in agreement with empirical data.
These results imply that bidding at the last moment is a rational and effective
strategy to win in an eBay auction.Comment: 4 pages, 6 figure
Interstellar medium disruption in the Centaurus A group
We present the results of a 21 cm neutral hydrogen (HI) line detection
experiment in the direction of 18 low luminosity dwarf galaxies of the
Centaurus A group, using the Australia Telescope National Facility 64m Parkes
Radio Telescope and the Australia Telescope Compact Array. Five dwarfs have HI
masses between M_HI=4x10^5 to M_HI=2.1x10^7 Msol and 0.04<M_HI/L_B<1.81 Msol
L_{sol, B}^-1. The other 13 have upper-limits between M_HI<5x10^5 and
M_HI<4x10^6 Msol (M_HI}/L_B<0.24 Msol L_{sol, B}^-1). Two of the
mixed-morphology dwarfs remain undetected in HI, a situation that is in
contrast to that of similar Local Group and Sculptor group objects where all
contain significant amounts of neutral gas. There is a discontinuity in the HI
properties of Centaurus A group low luminosity dwarfs that is unobserved
amongst Sculptor group dwarfs. All objects fainter than M_B=-13 have either
M_HI>10^7 Msol or M_HI<10^6 Msol. This gap may be explained by the ram pressure
stripping mechanism at work in this dense environment where all galaxies with
M_HI<10^7 Msol have been stripped of their gas. The required intergalactic
medium density to achieve this is ~10^-3 cm^-3.Comment: 7 figures, 2 table
Open Gromov-Witten Invariants of Toric Calabi-Yau 3-Folds
We present a proof of the mirror conjecture of Aganagic-Vafa
[arXiv:hep-th/0012041] and Aganagic-Klemm-Vafa [arXiv:hep-th/0105045] on disk
enumeration in toric Calabi-Yau 3-folds for all smooth semi-projective toric
Calabi-Yau 3-folds. We consider both inner and outer branes, at arbitrary
framing. In particular, we recover previous results on the conjecture for (i)
an inner brane at zero framing in the total space of the canonical line bundle
of the projective plane (Graber-Zaslow [arXiv:hep-th/0109075]), (ii) an outer
brane at arbitrary framing in the resolved conifold (Zhou [arXiv:1001.0447]),
and (iii) an outer brane at zero framing in the total space of the canonical
line bundle of the projective plane (Brini [arXiv:1102.0281, Section 5.3]).Comment: 39 pages, 11 figure
One-Loop Self Energy and Renormalization of the Speed of Light for some Anisotropic Improved Quark Actions
One-loop corrections to the fermion rest mass M_1, wave function
renormalization Z_2 and speed of light renormalization C_0 are presented for
lattice actions that combine improved glue with clover or D234 quark actions
and keep the temporal and spatial lattice spacings, a_t and a_s, distinct. We
explore a range of values for the anisotropy parameter \chi = a_s/a_t and treat
both massive and massless fermions.Comment: 45 LaTeX pages with 4 postscript figure
On Markovian solutions to Markov Chain BSDEs
We study (backward) stochastic differential equations with noise coming from
a finite state Markov chain. We show that, for the solutions of these equations
to be `Markovian', in the sense that they are deterministic functions of the
state of the underlying chain, the integrand must be of a specific form. This
allows us to connect these equations to coupled systems of ODEs, and hence to
give fast numerical methods for the evaluation of Markov-Chain BSDEs
- âŠ