277 research outputs found
Continuous variable quantum cryptography
We propose a quantum cryptographic scheme in which small phase and amplitude
modulations of CW light beams carry the key information. The presence of EPR
type correlations provides the quantum protection.Comment: 8 pages, 3 figure
Using entanglement improves precision of quantum measurements
We show how entanglement can be used to improve the estimation of an unknown
transformation. Using entanglement is always of benefit, in improving either
the precision or the stability of the measurement. Examples relevant for
applications are illustrated, for either qubits and continuous variable
Path integrals on a flux cone
This paper considers the Schroedinger propagator on a cone with the conical
singularity carrying magnetic flux (``flux cone''). Starting from the operator
formalism and then combining techniques of path integration in polar
coordinates and in spaces with constraints, the propagator and its path
integral representation are derived. "Quantum correction" in the Lagrangian
appears naturally and no a priori assumption is made about connectivity of the
configuration space.Comment: LaTeX file, 9 page
Nonthermal Hard X-ray Emission and Iron Kalpha Emission from a Superflare on II Pegasi
We report on an X-ray flare detected on the active binary system II~Pegasi
with the Swift telescope. The trigger had a 10-200 keV luminosity of
2.2 erg s-- a superflare, by comparison with energies of
typical stellar flares on active binary systems. The trigger spectrum indicates
a hot thermal plasma with T180 K. X-ray spectral analysis
from 0.8--200 keV with the X-Ray Telescope and BAT in the next two orbits
reveals evidence for a thermal component (T80 K) and Fe K 6.4
keV emission. A tail of emission out to 200 keV can be fit with either an
extremely high temperature thermal plasma (TK) or power-law
emission. Based on analogies with solar flares, we attribute the excess
continuum emission to nonthermal thick-target bremsstrahlung emission from a
population of accelerated electrons. We estimate the radiated energy from
0.01--200 keV to be erg, the total radiated energy over
all wavelengths erg, the energy in nonthermal electrons above 20
keV erg, and conducted energy erg. The
nonthermal interpretation gives a reasonable value for the total energy in
electrons 20 keV when compared to the upper and lower bounds on the thermal
energy content of the flare. This marks the first occasion in which evidence
exists for nonthermal hard X-ray emission from a stellar flare. We investigate
the emission mechanism responsible for producing the 6.4 keV feature, and find
that collisional ionization from nonthermal electrons appears to be more
plausible than the photoionization mechanism usually invoked on the Sun and
pre-main sequence stars.Comment: 41 pages, 7 figures, accepted for publication in the Astrophysical
Journa
Toll-like receptor 2 and 4 have opposing roles in the pathogenesis of cigarette smoke-induced chronic obstructive pulmonary disease
© 2018 American Physiological Society. All rights reserved. Chronic obstructive pulmonary disease (COPD) is the third leading cause of morbidity and death and imposes major socioeconomic burdens globally. It is a progressive and disabling condition that severely impairs breathing and lung function. There is a lack of effective treatments for COPD, which is a direct consequence of the poor understanding of the underlying mechanisms involved in driving the pathogenesis of the disease. Toll-like receptor (TLR)2 and TLR4 are implicated in chronic respiratory diseases, including COPD, asthma and pulmonary fibrosis. However, their roles in the pathogenesis of COPD are controversial and conflicting evidence exists. In the current study, we investigated the role of TLR2 and TLR4 using a model of cigarette smoke (CS)-induced experimental COPD that recapitulates the hallmark features of human disease. TLR2, TLR4, and associated coreceptor mRNA expression was increased in the airways in both experimental and human COPD. Compared with wild-type (WT) mice, CS-induced pulmonary inflammation was unaltered in TLR2-deficient (Tlr2-/-) and TLR4-deficient (Tlr4-/-) mice. CS-induced airway fibrosis, characterized by increased collagen deposition around small airways, was not altered in Tlr2-/- mice but was attenuated in Tlr4-/- mice compared with CS-exposed WT controls. However, Tlr2-/- mice had increased CS-induced emphy-sema-like alveolar enlargement, apoptosis, and impaired lung function, while these features were reduced in Tlr4-/- mice compared with CS-exposed WT controls. Taken together, these data highlight the complex roles of TLRs in the pathogenesis of COPD and suggest that activation of TLR2 and/or inhibition of TLR4 may be novel therapeutic strategies for the treatment of COPD
Quantum nonlinear dynamics of continuously measured systems
Classical dynamics is formulated as a Hamiltonian flow on phase space, while
quantum mechanics is formulated as a unitary dynamics in Hilbert space. These
different formulations have made it difficult to directly compare quantum and
classical nonlinear dynamics. Previous solutions have focussed on computing
quantities associated with a statistical ensemble such as variance or entropy.
However a more direct comparison would compare classical predictions to the
quantum for continuous simultaneous measurement of position and momentum of a
single system. In this paper we give a theory of such measurement and show that
chaotic behaviour in classical systems can be reproduced by continuously
measured quantum systems.Comment: 11 pages, REVTEX, 3 figure
WDR19 : An ancient, retrograde, intraflagellar ciliary protein is mutated in autosomal recessive retinitis pigmentosa and in Senior‐Loken syndrome
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99013/1/cge12196.pd
Conditional probabilities for a single photon at a beam splitter
Published versio
Processing and Transmission of Information
Contains research objectives and reports on seven research projects.Lincoln Laboratory, Purchase Order DDL-B222Air Force under Air Force Contract AF19(604)-5200Office of Naval Research under Contract Nonr-1841(57
Multiple agency perspective, family control, and private information abuse in an emerging economy
Using a comprehensive sample of listed companies in Hong Kong this paper investigates how family control affects private information abuses and firm performance in emerging economies. We combine research on stock market microstructure with more recent studies of multiple agency perspectives and argue that family ownership and control over the board increases the risk of private information abuse. This, in turn, has a negative impact on stock market performance. Family control is associated with an incentive to distort information disclosure to minority shareholders and obtain private benefits of control. However, the multiple agency roles of controlling families may have different governance properties in terms of investors’ perceptions of private information abuse. These findings contribute to our understanding of the conflicting evidence on the governance role of family control within a multiple agency perspectiv
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