5,249 research outputs found
Entanglement for a Bimodal Cavity Field Interacting with a Two-Level Atom
Negativity has been adopted to investigate the entanglement in a system
composed of a two-level atom and a two-mode cavity field. Effects of Kerr-like
medium and the number of photon inside the cavity on the entanglement are
studied. Our results show that atomic initial state must be superposed, so that
the two cavity field modes can be entangled. Moreover, we also conclude that
the number of photon in the two cavity mode should be equal. The interaction
between modes, namely, the Kerr effect, has a significant negative
contribution. Note that the atom frequency and the cavity frequency have an
indistinguishable effect, so a corresponding approximation has been made in
this article. These results may be useful for quantum information in optics
systems.Comment: Accepted by Commun. Theor. Phy
Noncommutative Field Theory from twisted Fock space
We construct a quantum field theory in noncommutative spacetime by twisting
the algebra of quantum operators (especially, creation and annihilation
operators) of the corresponding quantum field theory in commutative spacetime.
The twisted Fock space and S-matrix consistent with this algebra have been
constructed. The resultant S-matrix is consistent with that of Filk\cite{Filk}.
We find from this formulation that the spin-statistics relation is not violated
in the canonical noncommutative field theories.Comment: 13 pages, 1 figure, minor changes, add reference
Clec9a-mediated ablation of conventional dendritic cells suggests a lymphoid path to generating dendritic cells In Vivo
Conventional dendritic cells (cDCs) are versatile activators of immune responses that develop as part of the myeloid lineage downstream of hematopoietic stem cells. We have recently shown that in mice precursors of cDCs, but not of other leukocytes, are marked by expression of DNGR-1/CLEC9A. To genetically deplete DNGR-1-expressing cDC precursors and their progeny, we crossed Clec9a-Cre mice to Rosa-lox-STOP-lox-diphtheria toxin (DTA) mice. These mice develop signs of age-dependent myeloproliferative disease, as has been observed in other DC-deficient mouse models. However, despite efficient depletion of cDC progenitors in these mice, cells with phenotypic characteristics of cDCs populate the spleen. These cells are functionally and transcriptionally similar to cDCs in wild type control mice but show somatic rearrangements of Ig-heavy chain genes, characteristic of lymphoid origin cells. Our studies reveal a previously unappreciated developmental heterogeneity of cDCs and suggest that the lymphoid lineage can generate cells with features of cDCs when myeloid cDC progenitors are impaired
Monovalent counterion distributions at highly charged water interfaces: Proton-transfer and Poisson-Boltzmann theory
Surface sensitive synchrotron-X-ray scattering studies reveal the
distributions of monovalent ions next to highly charged interfaces. A lipid
phosphate (dihexadecyl hydrogen-phosphate) was spread as a monolayer at the
air-water interface, containing CsI at various concentrations. Using anomalous
reflectivity off and at the Cs resonance, we provide, for the first
time, spatial counterion distributions (Cs) next to the negatively charged
interface over a wide range of ionic concentrations. We argue that at low salt
concentrations and for pure water the enhanced concentration of hydroniums
HO at the interface leads to proton-transfer back to the phosphate
group by a high contact-potential, whereas high salt concentrations lower the
contact-potential resulting in proton-release and increased surface
charge-density. The experimental ionic distributions are in excellent agreement
with a renormalized-surface-charge Poisson-Boltzmann theory without fitting
parameters or additional assumptions
Generalized Poincare algebras, Hopf algebras and kappa-Minkowski spacetime
We propose a generalized description for the kappa-Poincare-Hopf algebra as a
symmetry quantum group of underlying kappa-Minkowski spacetime. We investigate
all the possible implementations of (deformed) Lorentz algebras which are
compatible with the given choice of kappa-Minkowski algebra realization. For
the given realization of kappa-Minkowski spacetime there is a unique
kappa-Poincare-Hopf algebra with undeformed Lorentz algebra. We have
constructed a three-parameter family of deformed Lorentz generators with
kappa-Poincare algebras which are related to kappa-Poincare-Hopf algebra with
undeformed Lorentz algebra. Known bases of kappa-Poincare-Hopf algebra are
obtained as special cases. Also deformation of igl(4) Hopf algebra compatible
with the kappa-Minkowski spacetime is presented. Some physical applications are
briefly discussed.Comment: 15 pages; journal version; Physics Letters B (2012
Distributed fault estimation with randomly occurring uncertainties over sensor networks
This paper is concerned with the distributed fault estimation problem for a class of uncertain stochastic systems over sensor networks. The norm-bounded uncertainty enters into the system in a random way governed by a set of Bernoulli distributed white sequence. The purpose of the addressed problem is to design distributed fault estimators, via available output measurements from not only the individual sensor, but also its neighbouring sensors, such that the fault estimation error converges to zero exponentially in the mean square while the disturbance rejection attenuation is constrained to a give level by means of the H∞ performance index. Intensive stochastic analysis is carried out to obtain sufficient conditions for ensuring the exponential stability as well as prescribed H∞ performance for the overall estimation error dynamics. Simulation results are provided to demonstrate the effectiveness of the proposed fault estimation technique in this paper.This work was supported in part by the National Natural Science Foundation of China [ grant number 61329301], [grant number 61422301], [grant number 61374127]; the Outstanding Youth Science Foundation of Heilongjiang Province [grant number JC2015016]; the Alexander von Humboldt Foundation of Germany
Vertically Self-Gravitating ADAFs in the Presence of Toroidal Magnetic Field
Force due to the self-gravity of the disc in the vertical direction is
considered to study its possible effects on the structure of a magnetized
advection-dominated accretion disc. We present steady-sate self similar
solutions for the dynamical structure of such a type of the accretion flows.
Our solutions imply reduced thickness of the disc because of the self-gravity.
It also imply that the thickness of the disc will increase by adding the
magnetic field strength.Comment: Accepted for publication in Astrophysics and Space Science
Spin measurement of 4U 1543-47 with Insight-HXMT and NICER from its 2021 outburst: A test of accretion disk models at high luminosities
4U 1543--47 is one of a handful of known black hole candidates located in the
Milky Way Galaxy, and has undergone a very bright outburst in 2021, reaching a
total of 9 Crab, as observed by the Monitor of All-sky Image (MAXI), and
exceeding twice its Eddington luminosity. The unprecedented bright outburst of
4U 1543--47 provides a unique opportunity to test the behavior of accretion
disk models at high luminosities and accretion rates. In addition, we explore
the possibility of constraining the spin of the source at high accretion rates,
given that previous spin measurements of 4U 1543--47 have been largely
inconsistent with each other. We measure the spectral evolution of the source
throughout its outburst as observed by Insight-HXMT, and compare the behavior
of both the thin disk model kerrbb2, as well as the slim disk model slimbh up
to the Eddington limit for two different values of disk -viscosity. In
addition, given the behavior of these two models, we identify two `golden'
epochs for which it is most suitable to measure the spin with continuum
fitting.Comment: 10 pages, 6 figure
Measurements of Spin Polarization of Epitaxial SrRuO3 Thin Films
We have measured the transport spin-polarization of epitaxial thin films of
the conductive ferromagnetic oxide, SrRuO3, using Point Contact Andreev
Reflection Spectroscopy (PCAR). In spite of the fact that spin-up and spin-down
electronic densities of states at the Fermi level for SrRuO3 calculated from
band structure theory are practically the same, the experimental transport spin
polarization for these films was found to be about 50%. This result is a direct
consequence of the Fermi velocity disparity between the majority and minority
bands and is in good agreement with our theoretical estimates.Comment: 12 pages pdf onl
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