781 research outputs found
Mean Square Capacity of Power Constrained Fading Channels with Causal Encoders and Decoders
This paper is concerned with the mean square stabilization problem of
discrete-time LTI systems over a power constrained fading channel. Different
from existing research works, the channel considered in this paper suffers from
both fading and additive noises. We allow any form of causal channel
encoders/decoders, unlike linear encoders/decoders commonly studied in the
literature. Sufficient conditions and necessary conditions for the mean square
stabilizability are given in terms of channel parameters such as transmission
power and fading and additive noise statistics in relation to the unstable
eigenvalues of the open-loop system matrix. The corresponding mean square
capacity of the power constrained fading channel under causal encoders/decoders
is given. It is proved that this mean square capacity is smaller than the
corresponding Shannon channel capacity. In the end, numerical examples are
presented, which demonstrate that the causal encoders/decoders render less
restrictive stabilizability conditions than those under linear
encoders/decoders studied in the existing works.Comment: Accepted by the 54th IEEE Conference on Decision and Contro
Investigation of Langdon effect on the nonlinear evolution of SRS from the early-stage inflation to the late-stage development of secondary instabilities
In a laser-irradiated plasma, the Langdon effect can result in a
super-Gaussian electron energy distribution function (EEDF), imposing
significant influences on the stimulated backward Raman scattering (SRS). In
this work, the influence of a super-Gaussian EEDF on the nonlinear evolution of
SRS is investigated by three wave model simulation and Vlasov-Maxwell
simulation for plasma parameters covering a wide range of k{\lambda}De from
0.19 to 0.48 at both high and low intensity laser drives. In the early-stage of
SRS evolution, it is found that besides the kinetic effects due to electron
trapping [Phys. Plasmas 25, 100702 (2018)], the Langdon effect can also
significantly widen the parameter range for the absolute growth of SRS, and the
time for the absolute SRS to reach saturation is greatly shorten by Langdon
effect within certain parameter region. In the late-stage of SRS, when
secondary instabilities such as decay of the electron plasma wave to beam
acoustic modes, rescattering, and Langmuir decay instability become important,
the Langdon effect can influence the reflectivity of SRS by affecting the
secondary processes. The comprehension of Langdon effect on nonlinear evolution
and saturation of SRS would contribute to a better understanding and prediction
of SRS in inertial confinement fusion
1-(2-Methoxyanilino)anthraquinone
In the title compound, C21H15NO3, the dihedral angle formed between the aromatic ring systems is 71.50 (3)°. The methoxy group is coplanar with the benzene ring to which it is connected, the C—O—C—C torsion angle being 6.37 (17)°. The observed conformation is stabilized by an intramolecular N—H⋯O hydrogen bond, generating an S(6) ring
Causal clustering: design of cluster experiments under network interference
This paper studies the design of cluster experiments to estimate the global
treatment effect in the presence of spillovers on a single network. We provide
an econometric framework to choose the clustering that minimizes the worst-case
mean-squared error of the estimated global treatment effect. We show that the
optimal clustering can be approximated as the solution of a novel penalized
min-cut optimization problem computed via off-the-shelf semi-definite
programming algorithms. Our analysis also characterizes easy-to-check
conditions to choose between a cluster or individual-level randomization. We
illustrate the method's properties using unique network data from the universe
of Facebook's users and existing network data from a field experiment
A Novel Role of Protein Tyrosine Kinase2 in Mediating Chloride Secretion in Human Airway Epithelial Cells
Ca2+ activated Cl− channels (CaCC) are up-regulated in cystic fibrosis (CF) airway surface epithelia. The presence and functional properties of CaCC make it a possible therapeutic target to compensate for the deficiency of Cl− secretion in CF epithelia. CaCC is activated by an increase in cytosolic Ca2+, which not only activates epithelial CaCCs, but also inhibits epithelial Na+ hyperabsorption, which may also be beneficial in CF. Our previous study has shown that spiperone, a known antipsychotic drug, activates CaCCs and stimulates Cl− secretion in polarized human non-CF and CF airway epithelial cell monolayers in vitro, and in Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) knockout mice in vivo. Spiperone activates CaCC not by acting in its well-known role as an antagonist of either 5-HT2 or D2 receptors, but through a protein tyrosine kinase-coupled phospholipase C-dependent pathway. Moreover, spiperone independently activates CFTR through a novel mechanism. Herein, we performed a mass spectrometry analysis and identified the signaling molecule that mediates the spiperone effect in activating chloride secretion through CaCC and CFTR. Proline-rich tyrosine kinase 2 (PYK2) is a non-receptor protein tyrosine kinase, which belongs to the focal adhesion kinase family. The inhibition of PYK2 notably reduced the ability of spiperone to increase intracellular Ca2+ and Cl− secretion. In conclusion, we have identified the tyrosine kinase, PYK2, as the modulator, which plays a crucial role in the activation of CaCC and CFTR by spiperone. The identification of this novel role of PYK2 reveals a new signaling pathway in human airway epithelial cells
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