3,783 research outputs found
Realization of All-or-nothing-type Kochen-Specker Experiment with Single Photons
Using the spontaneous parametric down-conversion process in a type-I phase
matching BBO crystal as single photon source, we perform an all-or-nothing-type
Kochen-Specker experiment proposed by Simon \QTR{it}{et al}. [Phys. Rev. Lett.
\QTR{bf}{85}, 1783 (2000)] to verify whether noncontextual hidden variables or
quantum mechanics is right. The results strongly agree with quantum mechanics.Comment: 3 figure
Synergism in Pharmacokinetics of Retagliptin and Metformin Observed during Clinical Trials of their Combination Therapy
Purpose: To investigate the safety and potential pharmacokinetic (PK) interaction between retagliptin, a selective inhibitor of dipeptidyl peptidase-4, and metformin in healthy subjects.Methods: In open-label, randomized, three-period, three-treatment crossover studies, 15 subjects received 100 mg retagliptin, 1500 mg metformin or the combination. The area under the curve from the time of dosing to infinity (AUCinf) and the maximum observed plasma concentration (Cmax) of each drug were measured.Results: The combination of retagliptin and metformin did not result in clinically significant alterations in the pharmacokinetics of SP2086 or metformin. The AUCinf and Cmax of retagliptin co-administered with metformin were 16.49 and 25.88 % higher than for retagliptin alone, respectively, while the AUCinf of metformin co-administered with retagliptin was 22.06 % higher than for metformin alone. The 90 % confidence interval of both glucose-lowering drugs’ AUCinf and Cmax of the geometric mean ratios of SP2086 + metformin fell within the pre-specified interval of 80 - 125 %. No laboratory adverse conditions occurred during the study. Retagliptin appeared generally safe and well-tolerated when administered alone or in combination with metformin.Conclusion: The results may be an indication that no dose adjustments are likely to be required when retagliptin is given in combination with metformin
A Correlation of Spectral Lag Evolution with Prompt Optical Emission in GRBs?
We report on observations of correlated behavior between the prompt gamma-ray
and optical emission from GRB 080319B, which (i) strongly suggest that they
occurred within the same astrophysical source region and (ii) indicate that
their respective radiation mechanisms were most likely dynamically coupled. Our
preliminary results, based upon a new cross-correlation function (CCF)
methodology for determining the time-resolved spectral lag, are summarized as
follows. First, the evolution in the arrival offset of prompt gamma-ray photon
counts between Swift-BAT 15-25 keV and 50-100 keV energy bands (intrinsic
gamma-ray spectral lag) appears to be anti-correlated with the arrival offset
between prompt 15-350 keV gamma-rays and the optical emission observed by
TORTORA (extrinsic optical/gamma-ray spectral lag), thus effectively
partitioning the burst into two main episodes at ~T+28+/-2 sec. Second, prompt
optical emission is nested within intervals of (a) trivial intrinsic gamma-ray
spectral lag (~T+12+-2 and ~T+50+/-2 sec) with (b) discontinuities in the hard
to soft evolution of the photon index for a power law fit to 15-150 keV
Swift-BAT data (~T+8+/-2 and ~T+48+/-1 sec), both of which coincide with the
rise (~T+10+/-1 sec) and decline (~T+50+/-1 sec) of prompt optical emission.
This potential discovery, robust across heuristic permutations of BAT energy
channels and varying temporal bin resolution, provides the first observational
evidence for an implicit connection between spectral lag and the dynamics of
shocks in the context of canonical fireball phenomenology.Comment: 5 pages. Adapted from a contribution to the Proceedings of the 2008
Nanjing GRB Conference. Edited by Y. F. Huang, Z. G. Dai and B. Zhan
Hybrid quantum device based on NV centers in diamond nanomechanical resonators plus superconducting waveguide cavities
We propose and analyze a hybrid device by integrating a microscale diamond
beam with a single built-in nitrogen-vacancy (NV) center spin to a
superconducting coplanar waveguide (CPW) cavity. We find that under an ac
electric field the quantized motion of the diamond beam can strongly couple to
the single cavity photons via dielectric interaction. Together with the strong
spin-motion interaction via a large magnetic field gradient, it provides a
hybrid quantum device where the dia- mond resonator can strongly couple both to
the single microwave cavity photons and to the single NV center spin. This
enables coherent information transfer and effective coupling between the NV
spin and the CPW cavity via mechanically dark polaritons. This hybrid
spin-electromechanical de- vice, with tunable couplings by external fields,
offers a realistic platform for implementing quantum information with single NV
spins, diamond mechanical resonators, and single microwave photons.Comment: Accepted by Phys. Rev. Applie
Comment on "Quantum key distribution without alternative measurements"
In a recent paper [A. Cabello, Phys. Rev. A 61, 052312 (2000)], a quantum key
distribution protocol based on entanglement swapping was proposed. However, in
this comment, it is shown that this protocol is insecure if Eve use a special
strategy to attack.Comment: 2 Pages, 1 Figur
Decoupling of the Antiferromagnetic and Insulating States in Tb doped Sr2IrO4
Sr2IrO4 is a spin-orbit coupled insulator with an antiferromagnetic (AFM)
transition at TN=240 K. We report results of a comprehensive study of
single-crystal Sr2Ir1-xTbxO4. This study found that mere 3% (x=0.03)
tetravalent Tb4+(4f7) substituting for Ir4+ (rather than Sr2+) completely
suppresses the long-range collinear AFM transition but retains the insulating
state, leading to a phase diagram featuring a decoupling of magnetic
interactions and charge gap. The insulating state at x=0.03 is characterized by
an unusually large specific heat at low temperatures and an incommensurate
magnetic state having magnetic peaks at (0.95, 0, 0) and (0, 0.95, 0) in the
neutron diffraction, suggesting a spiral or spin density wave order. It is
apparent that Tb doping effectively changes the relative strength of the SOI
and the tetragonal CEF and enhances the Hund's rule coupling that competes with
the SOI, and destabilizes the AFM state. However, the disappearance of the AFM
accompanies no metallic state chiefly because an energy level mismatch for the
Ir and Tb sites weakens charge carrier hopping and renders a persistent
insulating state. This work highlights an unconventional correlation between
the AFM and insulating states in which the magnetic transition plays no
critical role in the formation of the charge gap in the iridate.Comment: 8 figure
Dependence of the decoherence of polarization states in phase-damping channels on the frequency spectrum envelope of photons
We consider the decoherence of photons suffering in phase-damping channels.
By exploring the evolutions of single-photon polarization states and two-photon
polarization-entangled states, we find that different frequency spectrum
envelopes of photons induce different decoherence processes. A white frequency
spectrum can lead the decoherence to an ideal Markovian process. Some color
frequency spectrums can induce asymptotical decoherence, while, some other
color frequency spectrums can make coherence vanish periodically with variable
revival amplitudes. These behaviors result from the non-Markovian effects on
the decoherence process, which may give rise to a revival of coherence after
complete decoherence.Comment: 7 pages, 4 figures, new results added, replaced by accepted versio
Magneto-optical properties of Co/ZnO multilayer films
Multilayer films of ZnO with Co were deposited on glass substrates then
annealed in a vacuum. The magnetisation of the films increased with annealing
but not the magnitude of the magneto-optical signals. The dielectric functions
for the films were calculated using the MCD spectra. A Maxwell Garnett theory
of a metallic Co/ZnO mixture is presented. The extent to which this explains
the MCD spectra taken on the films is discussed.Comment: This paper was presented at ICM (2009) and is accepted in this form
for the proceeding
The `bare' strange stars might not be bare
It is proposed that the `bare' strange matter stars might not be bare, and
radio pulsars might be in fact `bare' strange stars. As strange matter stars
being intensely magnetized rotate, the induced unipolar electric fields would
be large enough to construct magnetospheres. This situation is very similar to
that discussed by many authors for rotating neutron stars. Also, the strange
stars with accretion crusts in binaries could act as X-ray pulsars or X-ray
bursters. There are some advantages if radio pulsars are `bare' strange stars.Comment: 11 pages, 1 Postscript figures, LaTeX, Chin. Phys. Lett. 1998,
Vol.15, Nov.12, p.93
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