652 research outputs found
Partially Linear Estimation with Application to Sparse Signal Recovery From Measurement Pairs
We address the problem of estimating a random vector X from two sets of
measurements Y and Z, such that the estimator is linear in Y. We show that the
partially linear minimum mean squared error (PLMMSE) estimator does not require
knowing the joint distribution of X and Y in full, but rather only its
second-order moments. This renders it of potential interest in various
applications. We further show that the PLMMSE method is minimax-optimal among
all estimators that solely depend on the second-order statistics of X and Y. We
demonstrate our approach in the context of recovering a signal, which is sparse
in a unitary dictionary, from noisy observations of it and of a filtered
version of it. We show that in this setting PLMMSE estimation has a clear
computational advantage, while its performance is comparable to
state-of-the-art algorithms. We apply our approach both in static and dynamic
estimation applications. In the former category, we treat the problem of image
enhancement from blurred/noisy image pairs, where we show that PLMMSE
estimation performs only slightly worse than state-of-the art algorithms, while
running an order of magnitude faster. In the dynamic setting, we provide a
recursive implementation of the estimator and demonstrate its utility in the
context of tracking maneuvering targets from position and acceleration
measurements.Comment: 13 pages, 5 figure
Novel mechanistic insights into viral modulation of immune receptor signaling
In this Opinion, based on a novel model of immune signaling, the Signaling Chain HOmoOLigomerization (SCHOOL) model, I suggest specific mechanisms used by different viruses such as human immunodeficiency virus (HIV), cytomegalovirus (CMV), severe acute respiratory syndrome coronavirus (SARS-CoV), herpesvirus saimiri (HVS), human herpesvirus 6 (HHV-6), etc., to modulate the host immune response mediated by members of the family of multichain immune recognition receptors (MIRRs). I also demonstrate how the SCHOOL model, together with the lessons learned from viral pathogenesis, can be used practically for rational drug design and the development of new therapies for immune disorders
Microwave whirlpools in a rectangular-waveguide cavity with a thin ferrite disk
We study a three dimensional system of a rectangular-waveguide resonator with
an inserted thin ferrite disk. The interplay of reflection and transmission at
the disk interfaces together with material gyrotropy effect, gives rise to a
rich variety of wave phenomena. We analyze the wave propagation based on full
Maxwell-equation numerical solutions of the problem. We show that the
power-flow lines of the microwave-cavity field interacting with a ferrite disk,
in the proximity of its ferromagnetic resonance, form whirlpool-like
electromagnetic vortices. Such vortices are characterized by the dynamical
symmetry breaking. The role of ohmic losses in waveguide walls and dielectric
and magnetic losses in a disk is a subject of our investigations
Effective chiral magnetic currents, topological magnetic charges, and microwave vortices in a cavity with an enclosed ferrite disk
In microwaves, a TE-polarized rectangular-waveguide resonator with an
inserted thin ferrite disk gives an example of a nonintegrable system. The
interplay of reflection and transmission at the disk interfaces together with
the material gyrotropy effect gives rise to whirlpool-like electromagnetic
vortices in the proximity of the ferromagnetic resonance. Based on numerical
simulation, we show that a character of microwave vortices in a cavity can be
analyzed by means of consideration of equivalent magnetic currents. Maxwell
equations allows introduction of a magnetic current as a source of the
electromagnetic field. Specifically, we found that in such nonintegrable
structures, magnetic gyrotropy and geometrical factors leads to the effect of
symmetry breaking resulting in effective chiral magnetic currents and
topological magnetic charges. As an intriguing fact, one can observe precessing
behavior of the electric-dipole polarization inside a ferrite disk.Comment: 9 figure
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