498 research outputs found
Certification of the Specific Micropore Volume and the Median Micropore Width of Two Microporous Reference Materials According to Draft-DIN 66135-4, BCR-704, BCR-705.
Abstract not availableJRC.D-Institute for Reference Materials and Measurements (Geel
Competitive stochastic noises in coherently driven two-level atoms and quantum interference
A system of coherently-driven two-level atoms is analyzed in presence of two
independent stochastic perturbations: one due to collisions and a second one
due to phase fluctuations of the driving field. The behaviour of the quantum
interference induced by the collisional noise is considered in detail. The
quantum-trajectory method is utilized to reveal the phase correlations between
the dressed states involved in the interfering transition channels. It is shown
that the quantum interference induced by the collisional noise is remarkably
robust against phase noise. This effect is due to the fact that the phase
noise, similarly to collisions, stabilizes the phase-difference between the
dressed states.Comment: accepted for publication in J. Opt.
Mounting, metrology and verification of Euclid near infrared spectro-photometer optical assembly NI-OA
Nonlinear magneto-optical rotation with frequency-modulated light in the geophysical field range
Recent work investigating resonant nonlinear magneto-optical rotation (NMOR)
related to long-lived (\tau\ts{rel} \sim 1 {\rm s}) ground-state atomic
coherences has demonstrated potential magnetometric sensitivities exceeding
for small () magnetic
fields. In the present work, NMOR using frequency-modulated light (FM NMOR) is
studied in the regime where the longitudinal magnetic field is in the
geophysical range (), of particular interest for many
applications. In this regime a splitting of the FM NMOR resonance due to the
nonlinear Zeeman effect is observed. At sufficiently high light intensities,
there is also a splitting of the FM NMOR resonances due to ac Stark shifts
induced by the optical field, as well as evidence of alignment-to-orientation
conversion type processes. The consequences of these effects for FM-NMOR-based
atomic magnetometry in the geophysical field range are considered.Comment: 8 pages, 8 figure
Temporal visual resolution and disease severity in MS
OBJECTIVE: To examine temporal visual resolution assessed as critical flicker frequency (CFF) in patients with MS and to investigate associations with visual system damage and general disability and cognitive function. METHODS: Thirty-nine patients with MS and 31 healthy controls (HCs) were enrolled in this cross-sectional study and underwent CFF testing, high- and low-contrast visual acuity, alertness and information processing speed using the paced auditory serial addition task (PASAT), and retinal optical coherence tomography (OCT). In patients with MS, visual evoked potentials (VEPs) and Expanded Disability Status Scale (EDSS) scores were assessed. RESULTS: CFF in patients with MS (mean ± SD: 40.9 ± 4.4 Hz) was lower than in HCs (44.8 ± 4.4 Hz, p < 0.001). There was no significant CFF difference between eyes with and without previous optic neuritis (ON). CFF was not associated with visual acuity, VEP latency, the peripapillary retinal nerve fiber layer thickness, and the combined ganglion cell and inner plexiform layer volume. Instead, reduced CFF was associated with worse EDSS scores (r(2) = 0.26, p < 0.001) and alertness (r(2) = 0.42, p = 0.00042) but not with PASAT (p = 0.33). CONCLUSION: CFF reduction in MS occurs independently of ON and structural visual system damage. Its association with the EDSS score and alertness suggests that CFF reflects global disease processes and higher cortical processing rather than focal optic nerve or retinal damage
Multiband theory of quantum-dot quantum wells: Dark excitons, bright excitons, and charge separation in heteronanostructures
Electron, hole, and exciton states of multishell CdS/HgS/CdS quantum-dot
quantum well nanocrystals are determined by use of a multiband theory that
includes valence-band mixing, modeled with a 6-band Luttinger-Kohn Hamiltonian,
and nonparabolicity of the conduction band. The multiband theory correctly
describes the recently observed dark-exciton ground state and the lowest,
optically active, bright-exciton states. Charge separation in pair states is
identified. Previous single-band theories could not describe these states or
account for charge separation.Comment: 10 pages of ReVTex, 6 ps figures, submitted to Phys. Rev.
Optimal geometry for efficient loading of an optical dipole trap
One important factor which determines efficiency of loading cold atoms into
an optical dipole trap from a magneto-optical trap is the distance between the
trap centers. By studying this efficiency for various optical trap depths
(2--110 mK) we find that for optimum dipole trap loading, longitudinal
displacements up to 15 mm are necessary. An explanation for this observation is
presented and compared with other work and a simple analytical formula is
derived for the optimum distance between the trap centers.Comment: 6 figures. Phys. Rev. A, in pres
Essential role of glucose transporter GLUT3 for post-implantation embryonic development
Deletion of glucose transporter gene Slc2a3 (GLUT3) has previously been reported to result in embryonic lethality. Here, we define the exact time point of growth arrest and subsequent death of the embryo. Slc2a3−/− morulae and blastocysts developed normally, implanted in vivo, and formed egg-cylinder-stage embryos that appeared normal until day 6·0. At day 6·5, apoptosis was detected in the ectodermal cells of Slc2a3−/− embryos resulting in severe disorganization and growth retardation at day 7·5 and complete loss of embryos at day 12·5. GLUT3 was detected in placental cone, in the visceral ectoderm and in the mesoderm of 7·5-day-old wild-type embryos. Our data indicate that GLUT3 is essential for the development of early post-implanted embryos
Energetic and spatial bonding properties from angular distributions of ultraviolet photoelectrons: application to the GaAs(110) surface
Angle-resolved ultraviolet photoemission spectra are interpreted by combining
the energetics and spatial properties of the contributing states. One-step
calculations are in excellent agreement with new azimuthal experimental data
for GaAs(110). Strong variations caused by the dispersion of the surface bands
permit an accurate mapping of the electronic structure. The delocalization of
the valence states is discussed analogous to photoelectron diffraction. The
spatial origin of the electrons is determined, and found to be strongly energy
dependent, with uv excitation probing the bonding region.Comment: 5 pages, 3 figures, submitted for publicatio
Oil and Gas Impacts in the Big Cypress Ecosystem: An Analysis of Impacts Associated with Proposed Activities in the Nobles Grade Area
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