2,664 research outputs found
Spin Squeezing via One-Axis Twisting with Coherent Light
We propose a new method of spin squeezing of atomic spin, based on the
interactions between atoms and off-resonant light which are known as
paramagnetic Faraday rotation and fictitious magnetic field of light. Since the
projection process, squeezed light, or special interactions among the atoms are
not required in this method, it can be widely applied to many systems. The
attainable range of the squeezing parameter is S^{-2/5}, where S is the total
spin, which is limited by additional fluctuations imposed by coherent light and
the spherical nature of the spin distribution.Comment: 4 pages,6 figure
The gray matter structural connectome and its relationship to alcohol relapse: Reconnecting for recovery.
Gray matter (GM) atrophy associated with alcohol use disorders (AUD) affects predominantly the frontal lobes. Less is known how frontal lobe GM loss affects GM loss in other regions and how it influences drinking behavior or relapse after treatment. The profile similarity index (PSI) combined with graph analysis allows to assess how GM loss in one region affects GM loss in regions connected to it, ie, GM connectivity. The PSI was used to describe the pattern of GM connectivity in 21 light drinkers (LDs) and in 54 individuals with AUD (ALC) early in abstinence. Effects of abstinence and relapse were determined in a subgroup of 36 participants after 3 months. Compared with LD, GM losses within the extended brain reward system (eBRS) at 1-month abstinence were similar between abstainers (ABST) and relapsers (REL), but REL had also GM losses outside the eBRS. Lower GM connectivities in ventro-striatal/hypothalamic and dorsolateral prefrontal regions and thalami were present in both ABST and REL. Between-networks connectivity loss of the eBRS in ABST was confined to prefrontal regions. About 3 months later, the GM volume and connectivity losses had resolved in ABST, and insula connectivity was increased compared with LD. GM losses and GM connectivity losses in REL were unchanged. Overall, prolonged abstinence was associated with a normalization of within-eBRS connectivity and a reconnection of eBRS structures with other networks. The re-formation of structural connectivities within and across networks appears critical for cognitive-behavioral functioning related to the capacity to maintain abstinence after outpatient treatment
Phase separation in the particle-hole asymmetric Hubbard model
The paramagnetic phase diagram of the Hubbard model with nearest-neighbor
(NN) and next-nearest-neighbor (NNN) hopping on the Bethe lattice is computed
at half-filling and in the weakly doped regime using the self-energy functional
approach for dynamical mean-field theory. NNN hopping breaks the particle-hole
symmetry and leads to a strong asymmetry of the electron-doped and hole-doped
regimes. Phase separation occurs at and near half-filling, and the critical
temperature of the Mott transition is strongly suppressed.Comment: 8 pages, 8 figure
Imprinting Patterns of Neutral Atoms in an Optical Lattice using Magnetic Resonance Techniques
We prepare arbitrary patterns of neutral atoms in a one-dimensional (1D)
optical lattice with single-site precision using microwave radiation in a
magnetic field gradient. We give a detailed account of the current limitations
and propose methods to overcome them. Our results have direct relevance for
addressing of planes, strings or single atoms in higher dimensional optical
lattices for quantum information processing or quantum simulations with
standard methods in current experiments. Furthermore, our findings pave the way
for arbitrary single qubit control with single site resolution.Comment: 9 pages, 7 figure
The transcriptome of Mycobacterium tuberculosis in a lipid-rich dormancy model through RNAseq analysis
Tuberculosis (TB) is currently the number one killer among infectious diseases worldwide. Lipids are abundant molecules during the infectious cycle of Mycobacterium tuberculosis (Mtb) and studies better mimicking its actual metabolic state during pathogenesis are needed. Though most studies have focused on the mycobacterial lipid metabolism under standard culture conditions, little is known about the transcriptome of Mtb in a lipid environment. Here we determined the transcriptome of Mtb H37Rv in a lipid-rich environment (cholesterol and fatty acid) under aerobic and hypoxic conditions, using RNAseq. Lipids significantly induced the expression of 368 genes. A main core lipid response was observed involving efflux systems, iron caption and sulfur reduction. In co-expression with ncRNAs and other genes discussed below, may act coordinately to prepare the machinery conferring drug tolerance and increasing a persistent population. Our findings could be useful to tag relevant pathways for the development of new drugs, vaccines and new strategies to control TB
Exact Ground States of the Periodic Anderson Model in D=3 Dimensions
We construct a class of exact ground states of three-dimensional periodic
Anderson models (PAMs) -- including the conventional PAM -- on regular Bravais
lattices at and above 3/4 filling, and discuss their physical properties. In
general, the f electrons can have a (weak) dispersion, and the hopping and the
non-local hybridization of the d and f electrons extend over the unit cell. The
construction is performed in two steps. First the Hamiltonian is cast into
positive semi-definite form using composite operators in combination with
coupled non-linear matching conditions. This may be achieved in several ways,
thus leading to solutions in different regions of the phase diagram. In a
second step, a non-local product wave function in position space is constructed
which allows one to identify various stability regions corresponding to
insulating and conducting states. The compressibility of the insulating state
is shown to diverge at the boundary of its stability regime. The metallic phase
is a non-Fermi liquid with one dispersing and one flat band. This state is also
an exact ground state of the conventional PAM and has the following properties:
(i) it is non-magnetic with spin-spin correlations disappearing in the
thermodynamic limit, (ii) density-density correlations are short-ranged, and
(iii) the momentum distributions of the interacting electrons are analytic
functions, i.e., have no discontinuities even in their derivatives. The
stability regions of the ground states extend through a large region of
parameter space, e.g., from weak to strong on-site interaction U. Exact
itinerant, ferromagnetic ground states are found at and below 1/4 filling.Comment: 47 pages, 10 eps figure
Cell adhesion and integrin binding to recombinant human fibrillin-1
AbstractFibrillin-1 is a major constituent of tissue microfibrils that occur in most connective tissues, either in close association with or independent of elastin. To test possible cell-adhesive functions of this protein, we used recombinant human fibrillin-1 polypeptides produced in a mammalian expression system in cell attachment and solid-phase integrin binding assays. Fibrillin-1 polypeptides containing the single RGD sequence located in the fourth 8-cysteine domain, mediated distinct cell adhesion of a variety of cell lines and bound to purified integrin αVβ3. Integrins αIIbβ3, α5β1, α2β1 and α1β1 did not interact with any of the recombinant fibrillin-1 peptides. Our results indicate a novel role for fibrillin-1 in cellular interactions mediated via an RGD motif that is appropriately exposed for recognition by integrin αVβ3
The Discovery of an Embedded Cluster of High-Mass Stars Near SGR 1900+14
Deep I-band imaging to approximately I = 26.5 of the soft gamma-ray repeater
SGR 1900+14 region has revealed a compact cluster of massive stars located only
a few arcseconds from the fading radio source thought to be the location of the
SGR (Frail, Kulkarni, & Bloom 1999). This cluster was previously hidden in the
glare of the pair of M5 supergiant stars (whose light was removed by PSF
subtraction) proposed by Vrba et al. (1996) as likely associated with the SGR
1900+14. The cluster has at least 13 members within a cluster radius of
approximately 0.6 pc, based on an estimated distance of 12-15 kpc. It is
remarkably similar to a cluster found associated with SGR 1806-20 (Fuchs et al.
1999). That similar clusters have now been found at or near the positions of
the two best-studied SGRs suggests that young neutron stars, thought to be
responsible for the SGR phenomenon, have their origins in proximate compact
clusters of massive stars.Comment: 5 pages, 3 figures, accepted Astrophysical Journal Letter
Failure time and microcrack nucleation
The failure time of samples of heterogeneous materials (wood, fiberglass) is
studied as a function of the applied stress. It is shown that in these
materials the failure time is predicted with a good accuracy by a model of
microcrack nucleation proposed by Pomeau. It is also shown that the crack
growth process presents critical features when the failure time is approached.Comment: 13 pages, 4 figures, submitted to Europhysics Letter
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