15,135 research outputs found
Computer model calibration with large non-stationary spatial outputs: application to the calibration of a climate model
Bayesian calibration of computer models tunes unknown input parameters by
comparing outputs with observations. For model outputs that are distributed
over space, this becomes computationally expensive because of the output size.
To overcome this challenge, we employ a basis representation of the model
outputs and observations: we match these decompositions to carry out the
calibration efficiently. In the second step, we incorporate the non-stationary
behaviour, in terms of spatial variations of both variance and correlations, in
the calibration. We insert two integrated nested Laplace
approximation-stochastic partial differential equation parameters into the
calibration. A synthetic example and a climate model illustration highlight the
benefits of our approach
Mixing of quasiparticle excitations and gamma-vibrations in transitional nuclei
Evidence of strong coupling of quasiparticle excitations with gamma-vibration
is shown to occur in transitional nuclei. High-spin band structures in
[166,168,170,172]Er are studied by employing the recently developed
multi-quasiparticle triaxial projected shell model approach. It is demonstrated
that a low-lying K=3 band observed in these nuclei, the nature of which has
remained unresolved, originates from the angular-momentum projection of
triaxially deformed two-quasiparticle (qp) configurations. Further, it is
predicted that the structure of this band depends critically on the shell
filling: in [166]Er the lowest K=3 2-qp band is formed from proton
configuration, in [168]Er the K=3 neutron and proton 2-qp bands are almost
degenerate, and for [170]Er and [172]Er the neutron K=3 2-qp band becomes
favored and can cross the gamma-vibrational band at high rotational
frequencies. We consider that these are few examples in even-even nuclei, where
the three basic modes of rotational, vibrational, and quasi-particle
excitations co-exist close to the yrast line.Comment: 7 pages, 6 figure
A closer look at arrested spinodal decomposition in protein solutions
Concentrated aqueous solutions of the protein lysozyme undergo a liquid solid
transition upon a temperature quench into the unstable spinodal region below a
characteristic arrest temperature of Tf=15C. We use video microscopy and
ultra-small angle light scattering in order to investigate the arrested
structures as a function of initial concentration, quench temperature and rate
of the temperature quench. We find that the solid-like samples show all the
features of a bicontinuous network that is formed through an arrested spinodal
decomposition process. We determine the correlation length Xi and demonstrate
that Xi exhibits a temperature dependence that closely follows the critical
scaling expected for density fluctuations during the early stages of spinodal
decomposition. These findings are in agreement with an arrest scenario based on
a state diagram where the arrest or gel line extends far into the unstable
region below the spinodal line. Arrest then occurs when during the early stage
of spinodal decomposition the volume fraction phi2 of the dense phase
intersects the dynamical arrest threshold phi2Glass, upon which phase
separation gets pinned into a space-spanning gel network with a characteristic
length Xi
Hall effects in Bose-Einstein condensates in a rotating optical lattice
Using the Kubo formalism, we demonstrate fractional quantum Hall features in
a rotating Bose-Einstein condensate in a co-rotating two-dimensional optical
lattice. The co-rotating lattice and trap potential allow for an effective
magnetic field and compensation of the centrifugal potential. Fractional
quantum Hall features are seen for the single-particle system and for few
strongly interacting many-particle systems.Comment: 11 pages, 13 figure
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