7,815 research outputs found
Density functional theory for strongly-correlated bosonic and fermionic ultracold dipolar and ionic gases
We introduce a density functional formalism to study the ground-state
properties of strongly-correlated dipolar and ionic ultracold bosonic and
fermionic gases, based on the self-consistent combination of the weak and the
strong coupling limits. Contrary to conventional density functional approaches,
our formalism does not require a previous calculation of the interacting
homogeneous gas, and it is thus very suitable to treat systems with tunable
long-range interactions. Due to its asymptotic exactness in the regime of
strong correlation, the formalism works for systems in which standard
mean-field theories fail.Comment: 5 pages, 2 figure
Pair-distribution functions of the two-dimensional electron gas
Based on its known exact properties and a new set of extensive fixed-node
reptation quantum Monte Carlo simulations (both with and without backflow
correlations, which in this case turn out to yield negligible improvements), we
propose a new analytical representation of (i) the spin-summed
pair-distribution function and (ii) the spin-resolved potential energy of the
ideal two-dimensional interacting electron gas for a wide range of electron
densities and spin polarization, plus (iii) the spin-resolved pair-distribution
function of the unpolarized gas. These formulae provide an accurate reference
for quantities previously not available in analytic form, and may be relevant
to semiconductor heterostructures, metal-insulator transitions and quantum dots
both directly, in terms of phase diagram and spin susceptibility, and
indirectly, as key ingredients for the construction of new two-dimensional spin
density functionals, beyond the local approximation.Comment: 12 pages, 10 figures; misprints correcte
A local density functional for the short-range part of the electron-electron interaction
Motivated by recent suggestions --to split the electron-electron interaction
into a short-range part, to be treated within the density functional theory,
and a long-range part, to be handled by other techniques-- we compute, with a
diffusion Monte Carlo method, the ground-state energy of a uniform electron gas
with a modified, short-range-only electron-electron interaction \erfc(\mu
r)/r, for different values of the cutoff parameter and of the electron
density. After deriving some exact limits, we propose an analytic
representation of the correlation energy which accurately fits our Monte Carlo
data and also includes, by construction, these exact limits, thus providing a
reliable ``short-range local-density functional''.Comment: 7 pages, 3 figure
Regularity of higher codimension area minimizing integral currents
This lecture notes are an expanded version of the course given at the
ERC-School on Geometric Measure Theory and Real Analysis, held in Pisa,
September 30th - October 30th 2013. The lectures aim to explain the main steps
of a new proof of the partial regularity of area minimizing integer rectifiable
currents in higher codimension, due originally to F. Almgren, which is
contained in a series of papers in collaboration with C. De Lellis (University
of Zurich).Comment: This text will appear in "Geometric Measure Theory and Real
Analysis", pp. 131--192, Proceedings of the ERC school in Pisa (2013), L.
Ambrosio Ed., Edizioni SNS (CRM Series
The cost of an ALP solution to the neutral -anomalies
The neutral anomalies in decays are analysed in terms of the tree-level
exchange of an axion-like-particle (ALP), within the effective field theory
framework. The complete two-dimensional parameter space for ALP couplings to
electrons and muons is explored. The solutions to and to the two energy
bins of are confronted with the impact of ALP exchange on other
observables (meson oscillations, leptonic and semileptonic decays of mesons
including searches for new resonances, astrophysical constraints), as well as
with the theoretical domain of validity of the effective theory. Solutions
based on ALPs heavier than mesons, or lighter than twice the muon mass, are
shown to be excluded. In contrast, the exchange of on-shell ALPs provides
solutions to and/or within sensitivity which are
technically compatible with those constraints; these solutions can be in
addition compatible with the data on the of the electron but not
simultaneously with those on the of the muon. Furthermore, a ''golden ALP
mass'' is identified at the frontier between the two energy bin windows of
, which could simultaneously explain these two
anomalies together with ; this calls for the convenience of different
energy binning which would easily clear up this (unlikely) possibility. The
impact of smearing on data analysis is also discussed.Comment: 50 pages, 15 figure
Pharmacokinetic profiles of the analgesic drug flupirtine in cats
Flupirtine (FLU) is a non-opioid analgesic drug with no antipyretic or antiphlogistic effects, used in the treatment of a wide range of pain states in human beings. There is a substantial body of evidence on the efficacy of FLU in humans but this is inadequate to recommend its off-label use in veterinary clinical practice. The aim of this study was to evaluate the pharmacokinetic profiles of FLU after IV and PO administration in healthy cats. Six mixed breed adult cats were randomly assigned to two treatment groups using an open, single-dose, two-treatment, two-phase, paired, cross-over design (2 × 2 Latin-square). Group 1 (n = 3) received a single dose of 5 mg/kg of FLU injected IV into the jugular vein. Group 2 (n = 3) received the same dose via PO route. The wash out period was 1 week. Blood samples (1 mL) were collected at assigned times and plasma was then analysed by a validated HPLC method.No adverse effects at the point of injection and no behavioural changes or alterations in health parameters were observed in the animals during or after the study (up to 7 days after the full study). After IV administration, FLU was detectable in plasma up to 36 h. After PO administration, FLU plasma concentrations were lower than those following IV administration, but they were detectable over the same time range. The terminal part of both mean pharmacokinetic curves showed a similar trend of elimination. The oral bioavailability was approximately 40%. This is the first study of FLU in an animal species of veterinary interest and it could pave the way for the use of this active ingredient in the veterinary field
The impact of SuperB on flavour physics
This report provides a succinct summary of the physics programme of SuperB,
and describes that potential in the context of experiments making measurements
in flavour physics over the next 10 to 20 years. Detailed comparisons are made
with Belle II and LHCb, the other B physics experiments that will run in this
decade. SuperB will play a crucial role in defining the landscape of flavour
physics over the next 20 years.Comment: 20 pages, 6 figure
Transmission studies and the composition of prokaryotic communities associated with healthy and diseased Aplysina cauliformis sponges suggest that Aplysina Red Band Syndrome is a prokaryotic polymicrobial disease
Aplysina cauliformis, the Caribbean purple rope sponge, is commonly affected by Aplysina Red Band Syndrome (ARBS). This transmissible disease manifests as circular lesions with red margins and results in bare spongin fibers. Leptolyngbya spp. appear to be responsible for the characteristic red coloration but transmission studies with a sponge-derived isolate failed to establish disease, leaving the etiology of ARBS unknown. To investigate the cause of ARBS, contact transmission experiments were performed between healthy and diseased sponges separated by filters with varying pore sizes. Transmission occurred when sponges were separated by filters with pore sizes ≥ 2.5 μm, suggesting a prokaryotic pathogen(s) but not completely eliminating eukaryotic pathogen(s). Using 16S rRNA gene sequencing methods, 38 prokaryotic taxa were significantly enriched in diseased sponges, including Leptolyngbya, whereas seven taxa were only found in some, but not all, of the ARBS-affected sponges. These results do not implicate a single taxon, but rather a suite of taxa that changed in relative abundance with disease, suggesting a polymicrobial etiology as well as dysbiosis. As a better understanding of dysbiosis is gained, changes in the composition of associated prokaryotic communities may have increasing importance for evaluating and maintaining the health of individuals and imperiled coral reef ecosystems
Vortex and half-vortex dynamics in a spinor quantum fluid of interacting polaritons
Spinorial or multi-component Bose-Einstein condensates may sustain fractional
quanta of circulation, vorticant topological excitations with half integer
windings of phase and polarization. Matter-light quantum fluids, such as
microcavity polaritons, represent a unique test bed for realising strongly
interacting and out-of-equilibrium condensates. The direct access to the phase
of their wavefunction enables us to pursue the quest of whether half vortices
---rather than full integer vortices--- are the fundamental topological
excitations of a spinor polariton fluid. Here, we are able to directly generate
by resonant pulsed excitations, a polariton fluid carrying either the half or
full vortex states as initial condition, and to follow their coherent evolution
using ultrafast holography. Surprisingly we observe a rich phenomenology that
shows a stable evolution of a phase singularity in a single component as well
as in the full vortex state, spiraling, splitting and branching of the initial
cores under different regimes and the proliferation of many vortex anti-vortex
pairs in self generated circular ripples. This allows us to devise the
interplay of nonlinearity and sample disorder in shaping the fluid and driving
the phase singularities dynamicsComment: New version complete with revised modelization, discussion and added
material. 8 pages, 7 figures. Supplementary videos:
https://drive.google.com/folderview?id=0B0QCllnLqdyBfmc2ai0yVF9fa2g2VnZodGUwemVkLThBb3BoOVRKRDJMS2dUdjlZdkRTQk
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