208 research outputs found
Detecting paired and counterflow superfluidity via dipole oscillations
We suggest an experimentally feasible procedure to observe paired and
counterflow superfluidity in ultra-cold atom systems. We study the time
evolution of one-dimensional mixtures of bosonic atoms in an optical lattice
following an abrupt displacement of an additional weak confining potential. We
find that the dynamic responses of the paired superfluid phase for attractive
inter-species interactions and the counterflow superfluid phase for repulsive
interactions are qualitatively distinct and reflect the quasi long-range order
that characterizes these states. These findings suggest a clear experimental
procedure to detect these phases, and give an intuitive insight into their
dynamics.Comment: 4 pages,5 figure
Anharmonicity Induced Resonances for Ultracold Atoms and their Detection
When two atoms interact in the presence of an anharmonic potential, such as
an optical lattice, the center of mass motion cannot be separated from the
relative motion. In addition to generating a confinement-induced resonance (or
shifting the position of an existing Feshbach resonance), the external
potential changes the resonance picture qualitatively by introducing new
resonances where molecular excited center of mass states cross the scattering
threshold. We demonstrate the existence of these resonances, give their
quantitative characterization in an optical superlattice, and propose an
experimental scheme to detect them through controlled sweeping of the magnetic
field.Comment: 6 pages, 5 figures; expanded presentatio
Emerging Bosons with Three-Body Interactions from Spin-1 Atoms in Optical Lattices
We study two many-body systems of bosons interacting via an infinite
three-body contact repulsion in a lattice: a pairs quasi-condensate induced by
correlated hopping and the discrete version of the Pfaffian wavefunction. We
propose to experimentally realise systems characterized by such interaction by
means of a proper spin-1 lattice Hamiltonian: spin degrees of freedom are
locally mapped into occupation numbers of emerging bosons, in a fashion similar
to spin-1/2 and hardcore bosons. Such a system can be realized with ultracold
spin-1 atoms in a Mott Insulator with filling-factor one. The high versatility
of these setups allows us to engineer spin-hopping operators breaking the SU(2)
symmetry, as needed to approximate interesting bosonic Hamiltonians with
three-body hardcore constraint. For this purpose we combine bichromatic
spin-independent superlattices and Raman transitions to induce a different
hopping rate for each spin orientation. Finally, we illustrate how our setup
could be used to experimentally realize the first setup, i.e. the transition to
a pairs quasi-condensed phase of the emerging bosons. We also report on a route
towards the realization of a discrete bosonic Pfaffian wavefunction and list
some open problems to reach this goal.Comment: 17 pages, 13 figure
Bose-Einstein Condensates in the Large Gas Parameter Regime
Bose-Einstein condensates of 10 Rb atoms in a cylindrical trap are
studied using a recently proposed modified Gross-Pitaevskii equation. The
existence of a Feshbach resonance allows for widely tuning the scattering
length of the atoms, and values of the peak gas parameter, , of the
order of 10 can be attained. We find large differences between the
results of the modified Gross-Pitaevskii and of the standard Thomas-Fermi, and
Gross-Pitaevskii equations in this region. The column densities at may
differ by as much as and the half maximum radius by . The
scattering lengths estimated by fitting the half maximum radius within
different approaches can differ by .Comment: 4 LaTeX pages, 2 figure
Spatial separation in a thermal mixture of ultracold Yb and Rb atoms
We report on the observation of unusually strong interactions in a thermal
mixture of ultracold atoms which cause a significant modification of the
spatial distribution. A mixture of Rb and Yb with a temperature
of a few K is prepared in a hybrid trap consisting of a bichromatic
optical potential superimposed on a magnetic trap. For suitable trap parameters
and temperatures, a spatial separation of the two species is observed. We infer
that the separation is driven by a large interaction strength between
Yb and Rb accompanied by a large three-body recombination rate.
Based on this assumption we have developed a diffusion model which reproduces
our observations
The criterion-related validity of the Northwick Park Dependency Score as a generic nursing dependency instrument for different rehabilitation patient groups
The criterion-related validity of the Northwick Park Dependency Score as a generic nursing dependency instrument for different rehabilitation patient groups
The criterion-related validity of the Northwick Park Dependency Score as a generic nursing dependency instrument for different rehabilitation patient groups
The criterion-related validity of the Northwick Park Dependency Score as a generic nursing dependency instrument for different rehabilitation patient groups
Objective: To investigate the criterion or concurrent validity of the Northwick Park Dependency Score (NPDS) for determining nursing dependence in different rehabilitation groups, with the Barthel Index (BI) and the Care Dependency Scale (C D S).Design: Cross-sectional study.Setting: Centre for Rehabilitation of the University Medical Center Groningen, The Netherlands.Subjects: Patients after stroke, spinal cord injury, multitrauma, head injury, amputation, rheumatoid arthritis, diabetes mellitus, lung diseases, tuberculosis and coronary artery disease. One hundred and fifty-four patients were included.Measures: The Northwick Park Dependency Score (NPDS), the Barthel Index (BI) and the Care Dependency Scale (CDS).Results: The correlation (rho) between the NPDS and the BI for all groups was - 0.87-1 R-2 = 0.76 (n = 154). Per patient group rho varied from - 0.70 (R-2 = 0.49) to - 0.93 (R-2 = 0.86). The overall correlation between the NPDS and CDS was larger than the criterion of rho = 0.60 (r=- 0.74; R-2 = 0.55) but was <0.60 in the rheumatoid arthritis and tuberculosis group. The overall correlation between BI and CDS exceeded the criterion (r = 0.75; R-2 = 0.56).Conclusions: The NPDS is a generic nursing dependency instrument that can be used as a valid measure across various patient groups in rehabilitation.</p
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