3,939 research outputs found
Gaussian potentials facilitate access to quantum Hall states in rotating Bose gases
Through exact numerical diagonalization for small numbers of atoms, we show
that it is possible to access quantum Hall states in harmonically confined Bose
gases at rotation frequencies well below the centrifugal limit by applying a
repulsive Gaussian potential at the trap center. The main idea is to reduce or
eliminate the effective trapping frequency in regions where the particle
density is appreciable. The critical rotation frequency required to obtain the
bosonic Laughlin state can be fixed at an experimentally accessible value by
choosing an applied Gaussian whose amplitude increases linearly with the number
of atoms while its width increases as the square root.Comment: 4 pages, 4 figure
Bundling Payment for Episodes of Hospital Care: Issues and Recommendations for the New Pilot Program in Medicare
Outlines the 2010 healthcare reform's provision to launch a pilot project for bundling Medicare payments around hospitalization episodes of care, the rationale for hospital episode bundling, and guidance on designing an effective pilot program
Analytical and experimental studies for predicting noise attenuation in acoustically treated ducts for turbofan engines
Analytical and experimental studies for predicting noise attenuation in acoustically treated ducts for turbofan engine
Constraint Satisfaction with Counting Quantifiers
We initiate the study of constraint satisfaction problems (CSPs) in the
presence of counting quantifiers, which may be seen as variants of CSPs in the
mould of quantified CSPs (QCSPs). We show that a single counting quantifier
strictly between exists^1:=exists and exists^n:=forall (the domain being of
size n) already affords the maximal possible complexity of QCSPs (which have
both exists and forall), being Pspace-complete for a suitably chosen template.
Next, we focus on the complexity of subsets of counting quantifiers on clique
and cycle templates. For cycles we give a full trichotomy -- all such problems
are in L, NP-complete or Pspace-complete. For cliques we come close to a
similar trichotomy, but one case remains outstanding. Afterwards, we consider
the generalisation of CSPs in which we augment the extant quantifier
exists^1:=exists with the quantifier exists^j (j not 1). Such a CSP is already
NP-hard on non-bipartite graph templates. We explore the situation of this
generalised CSP on bipartite templates, giving various conditions for both
tractability and hardness -- culminating in a classification theorem for
general graphs. Finally, we use counting quantifiers to solve the complexity of
a concrete QCSP whose complexity was previously open
- …