14,606 research outputs found
Nonlocal Position Changes of a Photon Revealed by Quantum Routers
Since its publication, Aharonov and Vaidman's three-box paradox has undergone
three major advances: i). A non-counterfactual scheme by the same authors in
2003 with strong rather than weak measurements for verifying the particle's
subtle presence in two boxes. ii) A realization of the latter by Okamoto and
Takeuchi in 2016. iii) A dynamic version by Aharonov et al. in 2017, with
disappearance and reappearance of the particle. We now combine these advances
together. Using photonic quantum routers the particle acts like a quantum
"shutter." It is initially split between Boxes A, B and C, the latter located
far away from the former two. The shutter particle's whereabouts can then be
followed by a probe photon, split in both space and time and reflected by the
shutter in its varying locations. Measuring the former is expected to reveal
the following time-evolution: The shutter particle was, with certainty, in
boxes A+C at t1, then only in C at t2, and finally in B+C at t3. Another branch
of the split probe photon can show that boxes A+B were empty at t2. A Bell-like
theorem applied to this experiment challenges any alternative interpretation
that avoids disappearance-reappearance in favor of local hidden variables.Comment: Revised versio
An evaluation of the analytic continuation by duality technique
In Nucl. Phys. B391 (1993) 127, the value of the oblique correction parameter
S for walking technicolor theories was estimated using a technique called
Analytic Continuation by Duality (ACD). We apply the ACD technique to the
perturbative vacuum polarization function and find that it fails to reproduce
the well known result S=1/6\pi. This brings into question the reliability of
the ACD technique and the ACD estimate of S.Comment: 8 pages, LaTeX, 1 postscript figure. Uses cite.sty, sprocl.sty, and
epsfig.sty. Talk presented at the 1996 International Workshop on Perspectives
of Strong Coupling Gauge Theories (SCGT'96), 13-16 Nov. 1996, Nagoy
Far-Ultraviolet and Far-Infrared Bivariate Luminosity Function of Galaxies: Complex Relation between Stellar and Dust Emission
Far-ultraviolet (FUV) and far-infrared (FIR) luminosity functions (LFs) of
galaxies show a strong evolution from to , but the FIR LF
evolves much stronger than the FUV one. The FUV is dominantly radiated from
newly formed short-lived OB stars, while the FIR is emitted by dust grains
heated by the FUV radiation field. It is known that dust is always associated
with star formation activity. Thus, both FUV and FIR are tightly related to the
star formation in galaxies, but in a very complicated manner. In order to
disentangle the relation between FUV and FIR emissions, we estimate the UV-IR
bivariate LF (BLF) of galaxies with {\sl GALEX} and {\sl AKARI} All-Sky Survey
datasets. Recently we invented a new mathematical method to construct the BLF
with given marginals and prescribed correlation coefficient. This method makes
use of a tool from mathematical statistics, so called "copula". The copula
enables us to construct a bivariate distribution function from given marginal
distributions with prescribed correlation and/or dependence structure. With
this new formulation and FUV and FIR univariate LFs, we analyze various FUV and
FIR data with {\sl GALEX}, {\sl Spitzer}, and {\sl AKARI} to estimate the UV-IR
BLF. The obtained BLFs naturally explain the nonlinear complicated relation
between FUV and FIR emission from star-forming galaxies. Though the faint-end
of the BLF was not well constrained for high- samples, the estimated linear
correlation coefficient was found to be very high, and is remarkably
stable with redshifts (from 0.95 at to 0.85 at ). This implies
the evolution of the UV-IR BLF is mainly due to the different evolution of the
univariate LFs, and may not be controlled by the dependence structure.Comment: 10 pages, 7 figures, Earth, Planets and Space, in pres
CP, T and CPT Violations in the K^0 - bar{K^0} System -- Present Status --
Possible violation of CP, T and CPT symmetries in the K^0 - bar{K^0} system
is studied in a way as phenomenological and comprehensive as possible. For this
purpose, we first introduce parameters which represent violation of these
symmetries in mixing parameters and decay amplitudes in a convenient and
well-defined way and, treating these parameters as small, derive formulas which
relate them to the experimentally measured quantities. We then perform
numerical analyses to derive constraints to these symmetry-violating
parameters, with the latest data reported by KTeV Collaboration, NA48
Collaboration and CPLEAR Collaboration, along with those compiled by Particle
Data Group, used as inputs. The result obtained by CPLEAR Collaboration from an
unconstrained fit to a time-dependent leptonic asymmetry, aided by the
Bell-Steinberger relation, enables us to determine or constrain most of the
parameters separately. It is shown among the other things that (1) CP and T
symmetries are violated definitively at least at the level of 10^{-4} in 2 pi
decays, (2) CP and T symmetries are violated at least at the level of 10^{-3}
in the K^0 - bar{K^0} mixing, and (3) CPT symmetry is at present tested to the
level of 10^{-5} at the utmost.Comment: 20 page
Lentiviral manipulation of gene expression in human adult and embryonic stem cells
Human stem cells could revolutionize the field of medicine by providing a diverse range of cell types for tissue replacement therapies and drug discovery. To achieve this goal, genetic tools need to be optimized and developed for controlling and manipulating stem cells ex vivo. Here we describe a lentiviral delivery system capable of high infection rates in human mesenchymal and embryonic stem cells. The lentiviral backbone was modified to express mono- and bi-cistronic transgenes and was also used to deliver short hairpin ribonucleic acid for specific silencing of gene expression in human stem cells. We show that lentiviral transduction can be used to alter gene expression without altering the genes' ability to differentiate in vitro. These vectors will enable rapid analysis of gene function in stem cells and permit the generation of knock-in / knock-out models of human disease in the rapidly developing field of gene therapy
Quantum filter for non-local polarization properties of photonic qubits
We present an optical filter that transmits photon pairs only if they share
the same horizontal or vertical polarization, without decreasing the quantum
coherence between these two possibilities. Various applications for
entanglement manipulations and multi-photon qubits are discussed.Comment: 7 pages, including one figure, short discussion of error sources
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Neutrinoless Double Beta Decay, the Inverted Hierarchy and Precision Determination of theta(12)
Ruling out the inverted neutrino hierarchy with neutrinoless double beta
decay experiments is possible if a limit on the effective mass below the
minimal theoretically possible value is reached. We stress that this lower
limit depends strongly on the value of the solar neutrino mixing angle: it
introduces an uncertainty of a factor of 2 within its current 3 sigma range. If
an experiment is not background-free, a factor of two in effective mass
corresponds to a combined factor of 16 improvement for the experimental
parameters running time, detector mass, background level and energy resolution.
Therefore, a more precise determination of theta(12) is crucial for the
interpretation of experimental results and the evaluation of the potential and
requirements for future experiments. We give the required half-lifes to exclude
(and touch) the inverted hierarchy regime for all double beta decay isotopes
with a Q-value above 2 MeV. The nuclear matrix elements from 6 different groups
and, if available, their errors are used and compared. We carefully put the
calculations on equal footing in what regards various convention issues. We
also use our compilation of matrix elements to give the reachable values of the
effective mass for a given half-life value.Comment: 26 pages, 6 figures. v2: error corrected (misprint in paper we took a
value from), slightly modifying the result
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