2,544 research outputs found
Single shot parameter estimation via continuous quantum measurement
We present filtering equations for single shot parameter estimation using
continuous quantum measurement. By embedding parameter estimation in the
standard quantum filtering formalism, we derive the optimal Bayesian filter for
cases when the parameter takes on a finite range of values. Leveraging recent
convergence results [van Handel, arXiv:0709.2216 (2008)], we give a condition
which determines the asymptotic convergence of the estimator. For cases when
the parameter is continuous valued, we develop quantum particle filters as a
practical computational method for quantum parameter estimation.Comment: 9 pages, 5 image
Driven transverse shear waves in a strongly coupled dusty plasma
The linear dispersion properties of transverse shear waves in a strongly
coupled dusty plasma are experimentally studied by exciting them in a
controlled manner with a variable frequency external source. The dusty plasma
is maintained in the strongly coupled fluid regime with (1 < Gamma << Gamma_c)
where Gamma is the Coulomb coupling parameter and Gamma_c is the
crystallization limit. A dispersion relation for the transverse waves is
experimentally obtained over a frequency range of 0.1 Hz to 2 Hz and found to
show good agreement with viscoelastic theoretical results.Comment: The manuscripts contains five pages and 6 figure
Highlights of the SLD Physics Program at the SLAC Linear Collider
Starting in 1989, and continuing through the 1990s, high-energy physics
witnessed a flowering of precision measurements in general and tests of the
standard model in particular, led by e+e- collider experiments operating at the
Z0 resonance. Key contributions to this work came from the SLD collaboration at
the SLAC Linear Collider. By exploiting the unique capabilities of this
pioneering accelerator and the SLD detector, including a polarized electron
beam, exceptionally small beam dimensions, and a CCD pixel vertex detector, SLD
produced a broad array of electroweak, heavy-flavor, and QCD measurements. Many
of these results are one of a kind or represent the world's standard in
precision. This article reviews the highlights of the SLD physics program, with
an eye toward associated advances in experimental technique, and the
contribution of these measurements to our dramatically improved present
understanding of the standard model and its possible extensions.Comment: To appear in 2001 Annual Review of Nuclear and Particle Science; 78
pages, 31 figures; A version with higher resolution figures can be seen at
http://www.slac.stanford.edu/pubs/slacpubs/8000/slac-pub-8985.html; Second
version incorporates minor changes to the tex
Involvement of beta-chemokines in the development of inflammatory demyelination.
The importance of beta-chemokines (or CC chemokine ligands - CCL) in the development of inflammatory lesions in the central nervous system of patients with multiple sclerosis and rodents with experimental allergic encephalomyelitis is strongly supported by descriptive studies and experimental models. Our recent genetic scans in families identified haplotypes in the genes of CCL2, CCL3 and CCL11-CCL8-CCL13 which showed association with multiple sclerosis. Complementing the genetic associations, we also detected a distinct regional expression regulation for CCL2, CCL7 and CCL8 in correlation with chronic inflammation in multiple sclerosis brains. These observations are in consensus with previous studies, and add new data to support the involvement of CCL2, CCL7, CCL8 and CCL3 in the development of inflammatory demyelination. Along with our own data, here we review the literature implicating CCLs and their receptors (CCRs) in multiple sclerosis and experimental allergic encephalomyelitis. The survey reflects that the field is in a rapid expansion, and highlights some of the pathways which might be suitable to pharmaceutical interventions
Involvement of ÎČ-chemokines in the development of inflammatory demyelination
The importance of ÎČ-chemokines (or CC chemokine ligands â CCL) in the development of inflammatory lesions in the central nervous system of patients with multiple sclerosis and rodents with experimental allergic encephalomyelitis is strongly supported by descriptive studies and experimental models. Our recent genetic scans in families identified haplotypes in the genes of CCL2, CCL3 and CCL11-CCL8-CCL13 which showed association with multiple sclerosis. Complementing the genetic associations, we also detected a distinct regional expression regulation for CCL2, CCL7 and CCL8 in correlation with chronic inflammation in multiple sclerosis brains. These observations are in consensus with previous studies, and add new data to support the involvement of CCL2, CCL7, CCL8 and CCL3 in the development of inflammatory demyelination. Along with our own data, here we review the literature implicating CCLs and their receptors (CCRs) in multiple sclerosis and experimental allergic encephalomyelitis. The survey reflects that the field is in a rapid expansion, and highlights some of the pathways which might be suitable to pharmaceutical interventions
A theory of the infinite horizon LQ-problem for composite systems of PDEs with boundary control
We study the infinite horizon Linear-Quadratic problem and the associated
algebraic Riccati equations for systems with unbounded control actions. The
operator-theoretic context is motivated by composite systems of Partial
Differential Equations (PDE) with boundary or point control. Specific focus is
placed on systems of coupled hyperbolic/parabolic PDE with an overall
`predominant' hyperbolic character, such as, e.g., some models for
thermoelastic or fluid-structure interactions. While unbounded control actions
lead to Riccati equations with unbounded (operator) coefficients, unlike the
parabolic case solvability of these equations becomes a major issue, owing to
the lack of sufficient regularity of the solutions to the composite dynamics.
In the present case, even the more general theory appealing to estimates of the
singularity displayed by the kernel which occurs in the integral representation
of the solution to the control system fails. A novel framework which embodies
possible hyperbolic components of the dynamics has been introduced by the
authors in 2005, and a full theory of the LQ-problem on a finite time horizon
has been developed. The present paper provides the infinite time horizon
theory, culminating in well-posedness of the corresponding (algebraic) Riccati
equations. New technical challenges are encountered and new tools are needed,
especially in order to pinpoint the differentiability of the optimal solution.
The theory is illustrated by means of a boundary control problem arising in
thermoelasticity.Comment: 50 pages, submitte
Multiple Object Tracking in Urban Traffic Scenes with a Multiclass Object Detector
Multiple object tracking (MOT) in urban traffic aims to produce the
trajectories of the different road users that move across the field of view
with different directions and speeds and that can have varying appearances and
sizes. Occlusions and interactions among the different objects are expected and
common due to the nature of urban road traffic. In this work, a tracking
framework employing classification label information from a deep learning
detection approach is used for associating the different objects, in addition
to object position and appearances. We want to investigate the performance of a
modern multiclass object detector for the MOT task in traffic scenes. Results
show that the object labels improve tracking performance, but that the output
of object detectors are not always reliable.Comment: 13th International Symposium on Visual Computing (ISVC
Magnetometry via a double-pass continuous quantum measurement of atomic spin
We argue that it is possible in principle to reduce the uncertainty of an
atomic magnetometer by double-passing a far-detuned laser field through the
atomic sample as it undergoes Larmor precession. Numerical simulations of the
quantum Fisher information suggest that, despite the lack of explicit
multi-body coupling terms in the system's magnetic Hamiltonian, the parameter
estimation uncertainty in such a physical setup scales better than the
conventional Heisenberg uncertainty limit over a specified but arbitrary range
of particle number N. Using the methods of quantum stochastic calculus and
filtering theory, we demonstrate numerically an explicit parameter estimator
(called a quantum particle filter) whose observed scaling follows that of our
calculated quantum Fisher information. Moreover, the quantum particle filter
quantitatively surpasses the uncertainty limit calculated from the quantum
Cramer-Rao inequality based on a magnetic coupling Hamiltonian with only
single-body operators. We also show that a quantum Kalman filter is
insufficient to obtain super-Heisenberg scaling, and present evidence that such
scaling necessitates going beyond the manifold of Gaussian atomic states.Comment: 17 pages, updated to match print versio
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