1,349 research outputs found
Quantum Turbulent Structure in Light
The infinite superpositions of random plane waves are known to be threaded
with vortex line singularities which form complicated tangles and obey strict
topological rules. We observe that within these structures a timelike axis
appears to emerge with which we can define vortex velocities in a useful way:
with both numerical simulations and optical experiments, we show that the
statistics of these velocities match those of turbulent quantum fluids such as
superfluid helium and atomic Bose-Einstein condensates. These statistics are
shown to be independent of system scale. These results raise deep questions
about the general nature of quantum chaos and the role of nonlinearity in the
structure of turbulence.Comment: 4 pages, 2 figure
Thomas-Fermi Approximation for a Condensate with Higher-order Interactions
We consider the ground state of a harmonically trapped Bose-Einstein
condensate within the Gross-Pitaevskii theory including the effective-range
corrections for a two-body zero-range potential. The resulting non-linear
Schr\"odinger equation is solved analytically in the Thomas-Fermi approximation
neglecting the kinetic energy term. We present results for the chemical
potential and the condensate profiles, discuss boundary conditions, and compare
to the usual Thomas-Fermi approach. We discuss several ways to increase the
influence of effective-range corrections in experiment with magnetically
tunable interactions. The level of tuning required could be inside experimental
reach in the near future.Comment: 8 pages, RevTex4 format, 5 figure
The Transverse Structure of the Baryon Source in Relativistic Heavy Ion Collisions
A direct method to reconstruct the transverse structure of the baryon source
formed in a relativistic heavy ion collision is presented. The procedure makes
use of experimentally measured proton and deuteron spectra and assumes that
deuterons are formed via two-nucleon coalescence. The transverse density shape
and flow profile are reconstructed for Pb+Pb collisions at the CERN-SPS. The
ambiguity with respect to the source temperature is demonstrated and possible
ways to resolve it are discussed.Comment: 15 pages LaTeX, 4 postscript figures, uses psfig.sty - Revised
version, few minor change
A somatosensory circuit for cooling perception in mice
The temperature of an object provides important somatosensory information for animals performing tactile tasks. Humans can perceive skin cooling of less than one degree, but the sensory afferents and central circuits that they engage to enable the perception of surface temperature are poorly understood. To address these questions, we examined the perception of glabrous skin cooling in mice. We found that mice were also capable of perceiving small amplitude skin cooling and that primary somatosensory (S1) cortical neurons were required for cooling perception. Moreover, the absence of the menthol-gated transient receptor potential melastatin 8 ion channel in sensory afferent fibers eliminated the ability to perceive cold and the corresponding activation of S1 neurons. Our results identify parts of a neural circuit underlying cold perception in mice and provide a new model system for the analysis of thermal processing and perception and multimodal integration
Cosmological stretching of perturbations on a cosmic string
We investigate the effects of cosmological expansion on the spectrum of
small-scale structure on a cosmic string. We simulate the evolution of a string
with two modes that differ in wavelength by one order of magnitude. Once the
short mode is inside the horizon, we find that its physical amplitude remains
unchanged, in spite of the fact that its comoving wavelength decreases as the
longer mode enters the horizon. Thus the ratio of amplitude to wavelength for
the short mode becomes larger than it would be in the absence of the long mode.Comment: 11 pages, 5 postscript figure
The master builders: LAIRAH research on good practice in the construction of digital humanities projects
Although many digital humanities resources are being developed for online use, there is little understanding of why some become popular, whilst others are neglected. Through log analysis techniques, the LAIRAH project identified twenty-one popular and well-used digital humanities projects, and in order to ascertain the factors they had in common, which predisposed them to be well used, conducted in-depth interviews with the creators of these resources. This article presents the findings of the study, highlighting areas that developers should be aware of, and providing a set of recommendations for both funders and creators, which should ensure that a digital humanities resource will have the best possible chance of being used in the long term
Detecting bubbles in exotic nuclei
The occurrence of a bubble, due to an inversion of s state with the
state usually located above, is investigated. Proton bubbles in neutron-rich
Argon isotopes are optimal candidates. Pairing effects which can play against
the bubble formation are evaluated. They cannot prevent bubble formation in
very neutron-rich argon isotopes such as Ar. This pleads for a
measurement of the charge density of neutron-rich argon isotopes in the
forthcoming years, with the advent of electron scattering experiments in next
generation exotic beam facilities such as FAIR or RIBF.Comment: 6 pages, 5 figures, to be published in Nucl. Phys.
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