804 research outputs found

### Vortex Phases of Rotating Superfluids

We report on the first mathematically rigorous proofs of a transition to a
giant vortex state of a superfluid in rotating anharmonic traps. The analysis
is carried out within two-dimensional Gross-Pitaevskii theory at large coupling
constant and large rotational velocity and is based on precise asymptotic
estimates on the ground state energy. An interesting aspect is a significant
difference between 'soft' anharmonic traps (like a quartic plus quadratic
trapping potential) and traps with a fixed boundary. In the former case
vortices persist in the bulk until the width of the annulus becomes comparable
to the size of the vortex cores. In the second case the transition already
takes place in a parameter regime where the size of vortices is very small
relative to the width of the annulus. Moreover, the density profiles in the
annulus are different in the two cases. In both cases rotational symmetry of
the density in a true ground state is broken, even though a symmetric
variational ansatz gives an excellent approximation to the energy.Comment: For the Proceedings of 21st International Laser Physics Workshop,
Calgary, July 23-27, 201

### The FFOCI, and Other Measures and Models of OCPD

The Five Factor Obsessive Compulsive Inventory (FFOCI) was developed in part to facilitate a shift from the categorical classification of personality disorder to a dimensional model; more specifically, the five-factor model. Questions though have been raised as to whether obsessive-compulsive personality disorder can be understood as a maladaptive variant of FFM conscientiousness. The purpose of the present study was to provide a further validation of the FFOCI, as well as to compare and contrast alternative measures and models of OCPD. A total of 380 participants, including 146 oversampled for OCPD traits, were recruited from introductory psychology courses at the University of Kentucky. Administered were the FFOCI, measures of general personality (e.g.,, International Item Pool, 5-Dimensional Personality Test), trait scales associated with OCPD (e.g.,, workaholism, compulsivity, propriety), and alternative measures of obsessive compulsive personality disorder. All measures were administered via SurveyMonkey, a secure online survey service. Results supported the validity of the FFOCI, but also demonstrated substantive differences among the alternative measures of OCPD, particularly with respect to their relationship with FFM conscientiousness, antagonism, and introversion

### Constraint satisfaction problems for reducts of homogeneous graphs

For n >= 3, let (Hn, E) denote the n-th Henson graph, i.e., the unique countable homogeneous graph with exactly those finite graphs as induced subgraphs that do not embed the complete graph on n vertices. We show that for all structures Gamma with domain Hn whose relations are first-order definable in (Hn, E) the constraint satisfaction problem for Gamma is either in P or is NP-complete. We moreover show a similar complexity dichotomy for all structures whose relations are first-order definable in a homogeneous graph whose reflexive closure is an equivalence relation. Together with earlier results, in particular for the random graph, this completes the complexity classification of constraint satisfaction problems of structures first-order definable in countably infinite homogeneous graphs: all such problems are either in P or NP-complete

### Random Unitaries Give Quantum Expanders

We show that randomly choosing the matrices in a completely positive map from
the unitary group gives a quantum expander. We consider Hermitian and
non-Hermitian cases, and we provide asymptotically tight bounds in the
Hermitian case on the typical value of the second largest eigenvalue. The key
idea is the use of Schwinger-Dyson equations from lattice gauge theory to
efficiently compute averages over the unitary group.Comment: 14 pages, 1 figur

### Spatiotemporal Response of Crystals in X-ray Bragg Diffraction

The spatiotemporal response of crystals in x-ray Bragg diffraction resulting
from excitation by an ultra-short, laterally confined x-ray pulse is studied
theoretically. The theory presents an extension of the analysis in symmetric
reflection geometry [1] to the generic case, which includes Bragg diffraction
both in reflection (Bragg) and transmission (Laue) asymmetric scattering
geometries. The spatiotemporal response is presented as a product of a
crystal-intrinsic plane wave spatiotemporal response function and an envelope
function defined by the crystal-independent transverse profile of the incident
beam and the scattering geometry. The diffracted wavefields exhibit amplitude
modulation perpendicular to the propagation direction due to both angular
dispersion and the dispersion due to Bragg's law. The characteristic measure of
the spatiotemporal response is expressed in terms of a few parameters: the
extinction length, crystal thickness, Bragg angle, asymmetry angle, and the
speed of light. Applications to self-seeding of hard x-ray free electron lasers
are discussed, with particular emphasis on the relative advantages of using
either the Bragg or Laue scattering geometries. Intensity front inclination in
asymmetric diffraction can be used to make snapshots of ultra-fast processes
with femtosecond resolution

### Time dependence of Bragg forward scattering and self-seeding of hard x-ray free-electron lasers

Free-electron lasers (FELs) can now generate temporally short, high power
x-ray pulses of unprecedented brightness, even though their longitudinal
coherence is relatively poor. The longitudinal coherence can be potentially
improved by employing narrow bandwidth x-ray crystal optics, in which case one
must also understand how the crystal affects the field profile in time and
space. We frame the dynamical theory of x-ray diffraction as a set of coupled
waves in order to derive analytic expressions for the spatiotemporal response
of Bragg scattering from temporally short incident pulses. We compute the
profiles of both the reflected and forward scattered x-ray pulses, showing that
the time delay of the wave $\tau$ is linked to its transverse spatial shift
$\Delta x$ through the simple relationship $\Delta x = c\tau \cot\theta$, where
$\theta$ is the grazing angle of incidence to the diffracting planes. Finally,
we apply our findings to obtain an analytic description of Bragg forward
scattering relevant to monochromatically seed hard x-ray FELs.Comment: 11 pages, 6 figure

### Information capacity of optical fiber channels with zero average dispersion

We study the statistics of optical data transmission in a noisy nonlinear
fiber channel with a weak dispersion management and zero average dispersion.
Applying path integral methods we have found exactly the probability density
functions of channel output both for a non-linear noisy channel and for a
linear channel with additive and multiplicative noise. We have obtained
analytically a lower bound estimate for the Shannon capacity of considered
nonlinear fiber channel.Comment: 4 pages, subbmited to Phys. Rev. Let

### Ultimate Precision of Adaptive Noise Estimation

We consider the estimation of noise parameters in a quantum channel, assuming the most general strategy allowed by quantum mechanics. This is based on the exploitation of unlimited entanglement and arbitrary quantum operations, so that the channel inputs may be interactively updated. In this general scenario, we draw a novel connection between quantum metrology and teleportation. In fact, for any teleportation-covariant channel (e.g., Pauli, erasure, or Gaussian channel), we find that adaptive noise estimation cannot beat the standard quantum limit, with the quantum Fisher information being determined by the channel’s Choi matrix. As an example, we establish the ultimate precision for estimating excess noise in a thermal-loss channel, which is crucial for quantum cryptography. Because our general methodology applies to any functional that is monotonic under trace-preserving maps, it can be applied to simplify other adaptive protocols, including those for quantum channel discrimination. Setting the ultimate limits for noise estimation and discrimination paves the way for exploring the boundaries of quantum sensing, imaging, and tomography

### Survivin a radiogenetic promoter for glioblastoma viral gene therapy independently from CArG motifs

BACKGROUND: Radiogenetic therapy is a novel approach in the treatment of cancer, which employs genetic modification to alter the sensitivity of tumor cells to the effect of applied radiation. AIM: To select a potent radiation inducible promoter in the context of brain tumors and to investigate if CArG radio responsive motifs or other elements in the promoter nucleotide sequences can correlate to its response to radiation. METHODS: To select initial candidates for promoter inducible elements, the levels of mRNA expression of six different promoters were assessed using Quantitative RTPCR in D54 MG cells before and after radiation exposure. Recombinant Ad/reporter genes driven by five different promoters; CMV, VEGF, FLT-1, DR5 and survivin were constructed. Glioma cell lines were infected with different multiplicity of infection of the (promoter) Ad or CMV Ad. Cells were then exposed to a range of radiation (0–12 Gy) at single fraction. Fluorescent microscopy, Luc assay and X-gal staining was used to detect the level of expression of related genes. Different glioma cell lines and normal astrocytes were infected with Ad survivin and exposed to radiation. The promoters were analyzed for presence of CArG radio-responsive motifs and CCAAT box consensus using NCBI blast bioinformatics software. RESULTS: Radiotherapy increases the expression of gene expression by 1.25–2.5 fold in different promoters other than survivin after 2 h of radiation. RNA analysis was done and has shown an increase in copy number of tenfold for survivin. Most importantly cells treated with RT and Ad Luc driven by survivin promoter showed a fivefold increase in expression after 2 Gy of radiation in comparison to non-irradiated cells. Presence or absence of CArG motifs did not correlate with promoter response to radiation. Survivin with the best response to radiation had the lowest number of CCAAT box. CONCLUSION: Survivin is a selective potent radiation inducible promoter for glioblastoma viral gene therapy and this response to radiation could be independent of CArG motifs

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