6,128 research outputs found
Kernel-based high-dimensional histogram estimation for visual tracking
©2008 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or distribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.Presented at the 15th IEEE International Conference on Image Processing, October 12–15, 2008, San Diego, California, U.S.A.DOI: 10.1109/ICIP.2008.4711862We propose an approach for non-rigid tracking that represents objects by their set of distribution parameters. Compared to joint histogram representations, a set of parameters such as mixed moments provides a significantly reduced size representation. The discriminating power is comparable to that of the corresponding full high dimensional histogram yet at far less spatial and computational complexity. The proposed method is robust in the presence of noise and illumination changes, and provides a natural extension to the use of mixture models. Experiments demonstrate that the proposed method outperforms both full color mean-shift and global covariance searches
A New Waveform Consistency Test for Gravitational Wave Inspiral Searches
Searches for binary inspiral signals in data collected by interferometric
gravitational wave detectors utilize matched filtering techniques. Although
matched filtering is optimal in the case of stationary Gaussian noise, data
from real detectors often contains "glitches" and episodes of excess noise
which cause filter outputs to ring strongly. We review the standard \chi^2
statistic which is used to test whether the filter output has appropriate
contributions from several different frequency bands. We then propose a new
type of waveform consistency test which is based on the time history of the
filter output. We apply one such test to the data from the first LIGO science
run and show that it cleanly distinguishes between true inspiral waveforms and
large-amplitude false signals which managed to pass the standard \chi^2 test.Comment: 10 pages, 6 figures, submitted to Classical and Quantum Gravity for
the proceedings of the Eighth Gravitational Wave Data Analysis Workshop
(GWDAW-8
Low-mass Tertiary Companions to Spectroscopic Binaries. I. Common Proper Motion Survey for Wide Companions Using 2MASS
We report the first results of a multi-epoch search for wide (separations greater than a few tens of AU), low-mass tertiary companions of a volume-limited sample of 118 known spectroscopic binaries within 30 pc of the Sun, using the Two Micron All Sky Survey Point Source Catalog and follow-up observations with the KPNO and CTIO 4 m telescopes. Note that this sample is not volume complete but volume limited, and, thus, there is incompleteness in our reported companion rates. We are sensitive to common proper motion companions with separations from roughly 200 AU to 10,000 AU (~10ˮ → ~ 10'). From 77 sources followed-up to date, we recover 11 previously known tertiaries, 3 previously known candidate tertiaries, of which 2 are spectroscopically confirmed and 1 rejected, and 3 new candidates, of which 2 are confirmed and 1 rejected. This yields an estimated wide tertiary fraction of 19.5^(+5.2)_(–3.7)%. This observed fraction is consistent with predictions set out in star formation simulations where the fraction of wide, low-mass companions to spectroscopic binaries is >10%
Unified study of glass and jamming rheology in soft particle systems
We explore numerically the shear rheology of soft repulsive particles at
large volume fraction. The interplay between viscous dissipation and thermal
motion results in multiple rheological regimes encompassing Newtonian,
shear-thinning and yield stress regimes near the `colloidal' glass transition
when thermal fluctuations are important, crossing over to qualitatively similar
regimes near the `jamming' transition when dissipation dominates. In the
crossover regime, glass and jamming sectors coexist and give complex flow
curves. Although glass and jamming limits are characterized by similar
macroscopic flow curves, we show that they occur over distinct time and stress
scales and correspond to distinct microscopic dynamics. We propose a simple
rheological model describing the glass to jamming crossover in the flow curves,
and discuss the experimental implications of our results.Comment: 5 pages, 3 figs; v2 accepted to publication to Phys. Rev. Let
Geometric quantum gate for trapped ions based on optical dipole forces induced by Gaussian laser beams
We present an implementation of quantum logic gates via internal state
dependent displacements of ions in a linear Paul trap caused by optical dipole
forces. Based on a general quantum analysis of the system dynamics we consider
specific implementations with alkaline earth ions. For experimentally realistic
parameters gate infidelities as low as can be obtained.Comment: 10 pages, 4 figure
Human Ecology Economics (HEE) and Strategic Management
Human Ecology Economics (HEE) draws on evolutionary and complex systems processes by incorporating interdisciplinary material from the humanities and sciences. Lessons for strategic managers follow from this HEE perspective with examples from the banking industry. HEE can nurture a broad environmental perspective among strategic managers and an ontological understanding of their organization within its dynamic ecology. Reconciliation is attempted between the chaotic dualities inherent in strategic management (SM)
A New Brown Dwarf Desert? A Scarcity of Wide Ultracool Binaries
We present the results of a deep-imaging search for wide companions to
low-mass stars and brown dwarfs using NSFCam on IRTF. We searched a sample of
132 M7-L8 dwarfs to magnitude limits of and ,
corresponding to secondary-primary mass ratios of . No companions
were found with separations between 2{\arcsec} to 31{\arcsec} (40 AU
to 1000 AU). This null result implies a wide companion frequency below
2.3% at the 95% confidence level within the sensitivity limits of the survey.
Preliminary modeling efforts indicate that we could have detected 85% of
companions more massive than and 50% above .Comment: 27 pages, 8 figures, 3 tables: accepted to the Astronomical Journa
Fractional Stokes-Einstein and Debye-Stokes-Einstein relations in a network forming liquid
We study the breakdown of the Stokes-Einstein (SE) and Debye-Stokes-Einstein
(DSE) relations for translational and rotational motion in a prototypical model
of a network-forming liquid, the ST2 model of water. We find that the emergence
of ``fractional'' SE and DSE relations at low temperature is ubiquitous in this
system, with exponents that vary little over a range of distinct physical
regimes. We also show that the same fractional SE relation is obeyed by both
mobile and immobile dynamical heterogeneities of the liquid
Star Formation via the Little Guy: A Bayesian Study of Ultracool Dwarf Imaging Surveys for Companions
I have undertaken a comprehensive statistical investigation of the ultracool
dwarf companion distribution (spectral type M6 and later). Utilizing a Bayesian
algorithm, I tested models of the companion distribution against data from an
extensive set of space and ground-based imaging observations of nearby
ultracool dwarfs. My main conclusions are fivefold: 1) Confirm that the
concentration of high mass ratio ultracool binary systems is a fundamental
feature of the companion distribution, not an observational or selection bias;
2) Determine that the wide (>~20 AU) binary frequency can be no more the 1-2%;
3) Show that the decreasing binary frequency with later spectral types is a
real trend; 4) Demonstrate that a large population of currently undetected low
mass ratio systems are not consistent with the current data; 5) Find that the
population of spectroscopic binaries must be be at least 30% that of currently
known ultracool binaries. The best fit value for the overall M6 and later
binary frequency is ~20%-22%, of which only ~6% consists of currently
undetected companions with separations less than 1 AU. If this is correct, then
the upper limit of the ultracool binary population discovered to date is ~75%.
I find that the numerical simulation results of the ejection formation method
are inconsistent with the outcome of this analysis. However, dynamics do seem
to play an important role as simulations of small-N clusters and triple system
decays produce results similar to those of this work. The observational efforts
required to improve these constraints are shown to be primarily large
spectroscopic binary surveys and improved high-resolution imaging techniques.Comment: 42 pages, 17 figures, to be published in October 2007 Ap
Representations of Time Coordinates in FITS
In a series of three previous papers, formulation and specifics of the
representation of World Coordinate Transformations in FITS data have been
presented. This fourth paper deals with encoding time. Time on all scales and
precisions known in astronomical datasets is to be described in an unambiguous,
complete, and self-consistent manner. Employing the well--established World
Coordinate System (WCS) framework, and maintaining compatibility with the FITS
conventions that are currently in use to specify time, the standard is extended
to describe rigorously the time coordinate. World coordinate functions are
defined for temporal axes sampled linearly and as specified by a lookup table.
The resulting standard is consistent with the existing FITS WCS standards and
specifies a metadata set that achieves the aims enunciated above.Comment: FITS WCS Paper IV: Time. 27 pages, 11 table
- …