552 research outputs found
Photonic properties of one-dimensionally-ordered cold atomic vapors under conditions of electromagnetically induced transparency
We experimentally study the photonic properties of a cold-atom sample trapped
in a one-dimensional optical lattice under the conditions of
electromagnetically induced transparency. We show that such a medium has two
photonic band gaps. One of them is in the transparency window and gives rise to
a Bragg mirror, which is spectrally very narrow and dynamically tunable. We
discuss the advantages and the limitations of this system. As an illustration
of a possible application we demonstrate a two-port all-optical switch
The tensor Goldstone multiplet for partially broken supersymmetry
We show that the tensor gauge multiplet of N=1 supersymmetry can serve as the
Goldstone multiplet for partially broken rigid N=2 supersymmetry. We exploit a
remarkable analogy with the Goldstone-Maxwell multiplet of hep-th/9608177 to
find its nonlinear transformation law and its invariant Goldstone action. We
demonstrate that the tensor multiplet has two dualities. The first transforms
it into the chiral Goldstone multiplet; the other leaves it invariant.Comment: 7 pages, Latex. Expanded discussion of duality symmetrie
Measurement of atomic diffraction phases induced by material gratings
Atom-surface interactions can significantly modify the intensity and phase of
atom de Broglie waves diffracted by a silicon nitride grating. This affects the
operation of a material grating as a coherent beam splitter. The phase shift
induced by diffraction is measured by comparing the relative phases of serveral
interfering paths in a Mach-Zehnder Na atom interferometer formed by three
material gratings. The values of the diffraction phases are consistent with a
simple model which includes a van der Waals atom-surface interaction between
the Na atoms and the silicon nitride grating bars.Comment: 4 pages, 5 figures, submitted to PR
Aberration cancellation in quantum interferometry
We report the first experimental demonstration of even-order aberration
cancellation in quantum interferometry. The effect is a spatial counterpart of
the spectral group velocity dispersion cancellation, which is associated with
spectral entanglement. It is manifested in temporal interferometry by virtue of
the multi-parameter spatial-spectral entanglement. Spatially-entangled photons,
generated by spontaneous parametric down conversion, were subjected to spatial
aberrations introduced by a deformable mirror that modulates the wavefront. We
show that only odd-order spatial aberrations affect the quality of quantum
interference
The complexity of Free-Flood-It on 2xn boards
We consider the complexity of problems related to the combinatorial game
Free-Flood-It, in which players aim to make a coloured graph monochromatic with
the minimum possible number of flooding operations. Our main result is that
computing the length of an optimal sequence is fixed parameter tractable (with
the number of colours present as a parameter) when restricted to rectangular
2xn boards. We also show that, when the number of colours is unbounded, the
problem remains NP-hard on such boards. This resolves a question of Clifford,
Jalsenius, Montanaro and Sach (2010)
Suppression of left-handed properties in disordered metamaterials
We study the effect of disorder on the effective magnetic response of
composite left-handed metamaterials and their specific properties such as
negative refraction. We show that relatively weak disorder in the split-ring
resonators can reduce and even completely eliminate the frequency domain where
the composite material demonstrates the left-handed properties. We introduce
the concept of the order parameter to describe novel physics of this effect.Comment: 4 pages, 2 figure
Pressure-induced phase transition in the electronic structure of palladium nitride
We present a combined theoretical and experimental study of the electronic
structure and equation of state (EOS) of crystalline PdN2. The compound forms
above 58 GPa in the pyrite structure and is metastable down to 11 GPa. We show
that the EOS cannot be accurately described within either the local density or
generalized gradient approximations. The Heyd-Scuseria-Ernzerhof
exchange-correlation functional (HSE06), however, provides very good agreement
with experimental data. We explain the strong pressure dependence of the Raman
intensities in terms of a similar dependence of the calculated band gap, which
closes just below 11 GPa. At this pressure, the HSE06 functional predicts a
first-order isostructural transition accompanied by a pronounced elastic
instability of the longitudinal-acoustic branches that provides the mechanism
for the experimentally observed decomposition. Using an extensive Wannier
function analysis, we show that the structural transformation is driven by a
phase transition of the electronic structure, which is manifested by a
discontinuous change in the hybridization between Pd-d and N-p electrons as
well as a conversion from single to triple bonded nitrogen dimers. We argue for
the possible existence of a critical point for the isostructural transition, at
which massive fluctuations in both the electronic as well as the structural
degrees of freedom are expected.Comment: 9 pages, 12 figures. Revised version corrects minor typographical
error
Reproduction Portrait of Abraham Lincoln by Alexander Gardner on November 15th 1863.
This is a reproduction photograph of Abraham Lincoln by Alexander Gardner. The original photograph taken in Washington on November 15th 1863.https://scholarsjunction.msstate.edu/fvw-artifacts/5775/thumbnail.jp
Detection of Marker Associated with CTC in Colorectal Cancer in Mononuclear Cells of Patients with Benign Inflammatory Intestinal Diseases
Colorectal carcinoma (CRC) belongs to the most common tumor entities in western countries. Circulating tumor cells (CTC) in blood of CRC patients are a powerful prognostic and predictive biomarker. However, whether CTC-associated markers can also be used for early CRC detection and discrimination from benign diseases is not known. This study investigated the presence of CTC-associated markers CK20, PLS3, LAD1, and DEFA5 in blood of patients with benign inflammatory intestinal disease (IID) and their correlation with malignancy. The detection rate of CK20 and DEFA5 significantly differed between diseased patients and healthy controls. LAD1 and PLS3 were detected in all samples with clear differences in gene expression. DEFA5 expression was higher in CRC and IID patients compared to healthy donors, while CK20 and PLS3 were lower in CRC compared to IID patients or healthy controls. Overall, all CTC-associated markers were detectable in blood of IID patients, but not correlating with inflammation severity. Finally, PLS3 emerged as a suitable marker for differentiation between malignant and non-malignant intestinal diseases or healthy controls, however its suitability for early CRC detection needs to be further validated
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