2,274 research outputs found
Efficient routing of single photons by one atom and a microtoroidal cavity
Single photons from a coherent input are efficiently redirected to a separate
output by way of a fiber-coupled microtoroidal cavity interacting with
individual Cesium atoms. By operating in an overcoupled regime for the
input-output to a tapered fiber, our system functions as a quantum router with
high efficiency for photon sorting. Single photons are reflected and excess
photons transmitted, as confirmed by observations of photon antibunching
(bunching) for the reflected (transmitted) light. Our photon router is robust
against large variations of atomic position and input power, with the observed
photon antibunching persisting for intracavity photon number 0.03 \lesssim n
\lesssim 0.7
Demonstration of a state-insensitive, compensated nanofiber trap
We report the experimental realization of an optical trap that localizes single Cs atoms ≃ 215
nm from surface of a dielectric nanober. By operating at magic wavelengths for pairs of counterpropagating
red- and blue-detuned trapping beams, dierential scalar light shifts are eliminated, and
vector shifts are suppressed by ≈ 250. We thereby measure an absorption linewidth Γ/2π = 5.7 ± 0.1
MHz for the Cs 6S_(1/2), F = 4 → 6P_(3/2), F' = 5 transition, where Γ_0/2π = 5.2 MHz in free space.
Optical depth d ≃ 66 is observed, corresponding to an optical depth per atom d_1 ≃ 0.08. These
advances provide an important capability for the implementation of functional quantum optical
networks and precision atomic spectroscopy near dielectric surfaces
Cystic fibrosis mice carrying the missense mutation G551D replicate human genotype phenotype correlations
We have generated a mouse carrying the human G551D mutation in the cystic fibrosis transmembrane conductance regulator gene (CFTR) by a one-step gene targeting procedure. These mutant mice show cystic fibrosis pathology but have a reduced risk of fatal intestinal blockage compared with 'null' mutants, in keeping with the reduced incidence of meconium ileus in G551D patients. The G551D mutant mice show greatly reduced CFTR-related chloride transport, displaying activity intermediate between that of cftr(mlUNC) replacement ('null') and cftr(mlHGU) insertional (residual activity) mutants and equivalent to approximately 4% of wild-type CFTR activity. The long-term survival of these animals should provide an excellent model with which to study cystic fibrosis, and they illustrate the value of mouse models carrying relevant mutations for examining genotype-phenotype correlations
The Opacity of Spiral Galaxy Disks V: dust opacity, HI distributions and sub-mm emission
The opacity of spiral galaxy disks, from counts of distant galaxies, is
compared to HI column densities. The opacity measurements are calibrated using
the ``Synthetic Field Method'' from Gonzalez et al (1998) and Holwerda et al.
(2005a).
When compared for individual disks, the HI column density and dust opacity do
not seem to be correlated as HI and opacity follow different radial profiles.
To improve statistics, an average radial opacity profile is compared to an
average HI profile. Compared to dust-to-HI estimates from the literature, more
extinction is found in this profile. This difference may be accounted for by an
underestimate of the dust in earlier measurements due to their dependence on
dust temperature. Since the SFM is insensitive to the dust temperature, the
ratio between the SFM opacity and HI could very well be indicative of the true
ratio.
Earlier claims for a radially extended cold dust disk were based on sub-mm
observations. A comparison between sub-mm observations and counts of distant
galaxies is therefore desirable. We present the best current example of such a
comparison, M51, for which the measurements seem to agree. However, this
remains an area where improved counts of distant galaxies, sub-mm observations
and our understanding of dust emissivity are needed.Comment: 8 pages, 5 figures, 1 table, accepted by A&
Solar variability indications from Nimbus 7 satellite data
The cavity pyrheliometer sensor of the Nimbus 7 Earth Radiation Experiment indicated low-level variability of the total solar irradiance. The variability appears to be inversely correlated with common solar activity indicators in an event sense. the limitations of the measuring system and available data sets are described
Widespread HCO emission in the M82's nuclear starburst
We present a high-resolution (~ 5'') image of the nucleus of M82 showing the
presence of widespread emission of the formyl radical (HCO). The HCO map, the
first obtained in an external galaxy, reveals the existence of a structured
disk of ~ 650 pc full diameter. The HCO distribution in the plane mimics the
ring morphology displayed by other molecular/ionized gas tracers in M82. More
precisely, rings traced by HCO, CO and HII regions are nested, with the HCO
ring lying in the outer edge of the molecular torus. Observations of HCO in
galactic clouds indicate that the abundance of HCO is strongly enhanced in the
interfaces between the ionized and molecular gas. The surprisingly high overall
abundance of HCO measured in M82 (X(HCO) ~ 4x10^{-10}) indicates that its
nuclear disk can be viewed as a giant Photon Dominated Region (PDR) of ~ 650 pc
size. The existence of various nested gas rings, with the highest HCO abundance
occurring at the outer ring (X(HCO) ~ 0.8x10^{-9}), suggests that PDR chemistry
is propagating in the disk. We discuss the inferred large abundances of HCO in
M82 in the context of a starburst evolutionary scenario, picturing the M82
nucleus as an evolved starburst.Comment: 13 pages, 3 figures, to appear in ApJ Letters; corrected list of
author
Probing lepton flavour violation in scattering and conversion on nucleons
We study lepton flavour-violating interactions which could result in the
-lepton production in the scattering or in
conversion on nucleons at high energies. Phenomenological bounds on the
strength of interactions are extracted from
the combined result of the NOMAD and CHORUS experiments on searching for
oscillations. Some of these bounds supersede limits
from rare decays. We also propose a ``missing energy'' type experiment
searching for conversion on nucleons. The experiment can be
performed at a present accelerator or at a future neutrino factory.Comment: 13 pages, 4 figure
Productive methods for oats in Missouri
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