25,153 research outputs found
Dynamics of Entanglement and Bell-nonlocality for Two Stochastic Qubits with Dipole-Dipole Interaction
We have studied the analytical dynamics of Bell nonlocality as measured by
CHSH inequality and entanglement as measured by concurrence for two noisy
qubits that have dipole-dipole interaction. The nonlocal entanglement created
by the dipole-dipole interaction is found to be protected from sudden death for
certain initial states
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Structural and electronic properties of SrZrO3 and Sr(Ti,Zr) O3 alloys
Using hybrid density functional calculations, we study the electronic and structural properties of SrZrO3 and ordered Sr(Ti,Zr)O3 alloys. Calculations were performed for the ground-state orthorhombic (Pnma) and high-temperature cubic (Pm3m) phases of SrZrO3. The variation of the lattice parameters and band gaps with Ti addition was studied using ordered SrTixZr1-xO3 structures with x=0, 0.25, 0.5, 0.75, and 1. As Ti is added to SrZrO3, the lattice parameter is reduced and closely follows Vegard's law. On the other hand, the band gap shows a large bowing and is highly sensitive to the Ti distribution. For x=0.5, we find that arranging the Ti and Zr atoms into a 1×1SrZrO3/SrTiO3 superlattice along the [001] direction leads to interesting properties, including a highly dispersive single band at the conduction-band minimum (CBM), which is absent in both parent compounds, and a band gap close to that of pure SrTiO3. These features are explained by the splitting of the lowest three conduction-band states due to the reduced symmetry of the superlattice, lowering the band originating from the in-plane Ti 3dxy orbitals. The lifting of the t2g orbital degeneracy around the CBM suppresses scattering due to electron-phonon interactions. Our results demonstrate how short-period SrZrO3/SrTiO3 superlattices could be exploited to engineer the band structure and improve carrier mobility compared to bulk SrTiO3
Mesoscopic Kondo effect of a quantum dot embedded in an Aharonov-Bohm ring with intradot spin-flip scattering
We study the Kondo effect in a quantum dot embedded in a mesoscopic ring
taking into account intradot spin-flip scattering . Based on the finite-
slave-boson mean-field approach, we find that the Kondo peak in the density of
states is split into two peaks by this coherent spin-flip transition, which is
responsible for some interesting features of the Kondo-assisted persistent
current circulating the ring: (1) strong suppression and crossover to a sine
function form with increasing ; (2) appearance of a "hump" in the
-dependent behavior for odd parity. -induced reverse of the persistent
current direction is also observed for odd parity.Comment: 7 pages,6 figures, to be published by Europhys. Let
Adopting a QCA Approach to Investigating the Risks Involved in Megaprojects from Auditing Perspective
There is an increase of megaproject construction worldwide. At the same time, risks involved in megaprojects have also become a wide concern. Extending from the macrolevel of qualitative analysis focusing on complexity, politics, and morality, the research conducted the microscopic empirical analysis on twenty-two typical cases by adopting the quality comparative analysis (QCA) from the auditing perspective. Different from the traditional analysis method taking each causation as independent variable, the results in the study revealed that there was complex multiple concurrent causation among eight conditions; additionally, the configuration of those would be divided into six types, among which, the coverage of the three types, namely, project management risk, preliminary and construction risk, and tendering and contract management related risk, was almost eighty percent. Finally, megaproject risks in China were caused by complicated and changeable combination conditions, which would provide a new breakthrough for seeking analyzing megaproject risks through this quantitative analysis method, and indicate the researchers and practitioners to control the megaproject risks from a more systematic way
Entropy and specific heat for open systems in steady states
The fundamental assumption of statistical mechanics is that the system is
equally likely in any of the accessible microstates. Based on this assumption,
the Boltzmann distribution is derived and the full theory of statistical
thermodynamics can be built. In this paper, we show that the Boltzmann
distribution in general can not describe the steady state of open system. Based
on the effective Hamiltonian approach, we calculate the specific heat, the free
energy and the entropy for an open system in steady states. Examples are
illustrated and discussed.Comment: 4 pages, 7 figure
Atom-molecule conversion with particle losses
Based on the mean-field approximation and the phase space analysis, we study
the dynamics of an atom-molecule conversion system subject to particle loss.
Starting from the many-body dynamics described by a master equation, an
effective nonlinear Schr\"odinger equation is introduced. The classical phase
space is then specified and classified by fixed points. The boundary, which
separate different dynamical regimes have been calculated and discussed. The
effect of particle loss on the conversion efficiency and the self-trapping is
explored.Comment: 6 pages, 5 figure
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Cirmtuzumab inhibits Wnt5a-induced Rac1 activation in chronic lymphocytic leukemia treated with ibrutinib.
Signaling via the B cell receptor (BCR) plays an important role in the pathogenesis and progression of chronic lymphocytic leukemia (CLL). This is underscored by the clinical effectiveness of ibrutinib, an inhibitor of Bruton's tyrosine kinase (BTK) that can block BCR-signaling. However, ibrutinib cannot induce complete responses (CR) or durable remissions without continued therapy, suggesting alternative pathways also contribute to CLL growth/survival that are independent of BCR-signaling. ROR1 is a receptor for Wnt5a, which can promote activation of Rac1 to enhance CLL-cell proliferation and survival. In this study, we found that CLL cells of patients treated with ibrutinib had activated Rac1. Moreover, Wnt5a could induce Rac1 activation and enhance proliferation of CLL cells treated with ibrutinib at concentrations that were effective in completely inhibiting BTK and BCR-signaling. Wnt5a-induced Rac1 activation could be blocked by cirmtuzumab (UC-961), an anti-ROR1 mAb. We found that treatment with cirmtuzumab and ibrutinib was significantly more effective than treatment with either agent alone in clearing leukemia cells in vivo. This study indicates that cirmtuzumab may enhance the activity of ibrutinib in the treatment of patients with CLL or other ROR1+ B-cell malignancies
Effect of chromatic dispersion induced chirp on the temporal coherence property of individual beam from spontaneous four wave mixing
Temporal coherence of individual signal or idler beam, determined by the
spectral correlation property of photon pairs, is important for realizing
quantum interference among independent sources. To understand the effect of
chirp on the temporal coherence property, two series of experiments are
investigated by introducing different amount of chirp into either the pulsed
pump or individual signal (idler) beam. In the first one, based on spontaneous
four wave mixing in a piece of optical fiber, the intensity correlation
function of the filtered individual signal beam, which characterizes the degree
of temporal coherence, is measured as a function of the chirp of pump. The
results demonstrate that the chirp of pump pulses decreases the degree of
temporal coherence. In the second one, a Hong-Ou-Mandel type two-photon
interference experiment with the signal beams generated in two different fibers
is carried out. The results illustrate that the chirp of individual beam does
not change the temporal coherence degree, but affect the temporal mode
matching. To achieve high visibility, apart from improving the coherence degree
by minimizing the chirp of pump, mode matching should be optimized by managing
the chirps of individual beams.Comment: 17pages, 4figure
Parsec-scale jet properties of the gamma-ray quasar 3C 286
The quasar 3C~286 is one of two compact steep spectrum sources detected by
the {\it Fermi}/LAT. Here, we investigate the radio properties of the
parsec(pc)-scale jet and its (possible) association with the -ray
emission in 3C~286. The Very Long Baseline Interferometry (VLBI) images at
various frequencies reveal a one-sided core--jet structure extending to the
southwest at a projected distance of 1 kpc. The component at the jet base
showing an inverted spectrum is identified as the core, with a mean brightness
temperature of ~K. The jet bends at about 600 pc (in
projection) away from the core, from a position angle of to
. Based on the available VLBI data, we inferred the proper motion
speed of the inner jet as mas yr (), corresponding to a jet speed of about at an inclination
angle of between the jet and the line of sight of the observer. The
brightness temperature, jet speed and Lorentz factor are much lower than those
of -ray-emitting blazars, implying that the pc-scale jet in 3C~286 is
mildly relativistic. Unlike blazars in which -ray emission is in
general thought to originate from the beamed innermost jet, the location and
mechanism of -ray emission in 3C~286 may be different as indicated by
the current radio data. Multi-band spectrum fitting may offer a complementary
diagnostic clue of the -ray production mechanism in this source.Comment: 9 pages, 4 figures, accept for publication in MNRA
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