Bose-Einstein Condensates with Large Number of Vortices

We show that as the number of vortices in a three dimensional Bose-Einstein Condensate increases, the system reaches a "quantum Hall" regime where the density profile is a Gaussian in the xy-plane and an inverted parabolic profile along z. The angular momentum of the system increases as the vortex lattice shrinks. However, Coriolis force prevents the unit cell of the vortex lattice from shrinking beyond a minimum size. Although the recent MIT experiment is not exactly in the quantum Hall regime, it is close enough for the present results to be used as a guide. The quantum Hall regime can be easily reached by moderate changes of the current experimental parameters.Comment: 4 pages, no figure

Extruding the vortex lattice: two reacting populations of dislocations

A controllable soft solid is realised in vortex matter in a type II superconductor. The two-dimensional unit cell area can be varied by a factor of $10^4$ in the solid phase, without a change of crystal symmetry offering easy exploration of extreme regimes compared to ordinary materials. The capacity to confine two-dimensional vortex matter to mesoscopic regions provides an arena for the largely unexplored metallurgy of plastic deformation at large density gradients. Our simulations reveal a novel plastic flow mechanism in this driven non-equilibrium system, utilising two distinct, but strongly interacting, populations of dislocations. One population facilitates the relaxation of density; a second aids the relaxation of shear stresses concentrated at the boundaries. The disparity of the bulk and shear moduli in vortex matter ensures the dislocation motion follows the overall continuum flow reflecting density variation

Disorder driven destruction of a phase transition in a superconductor

We investigate the effects of disorder on a layered superconductor. The clean system is known to have a first order phase transition which is clearly identified by a sharp peak in the specific heat. The peak is lost abruptly as the strength of the disorder is increased. Hence, for strong disorder there is no phase transition as a function of temperature but merely a crossover which is still detectable in the IV characteristic.Comment: 3 pages REVTeX , 5 figure

Substrate Specificity of Human Cutaneous Alcohol Dehydrogenase and Erythema Provoked by Lower Aliphatic Alcohols

The substrate utilization rates of human cutaneous alcohol dehydrogenase were determined for 7 lower aliphatic primary alcohols: ethanol, propanol, butanol, pentanol, 2-methylpropanol, 3-methylbutanol, and 2,2-dimethylpropanol. 1-Pentanol gave the highest relative activity and 2,2-dimethyipropanol the lowest. The frequency of erythemogenesis was determined in vivo for these 7 lower aliphatic primary alcohols. The frequency of erythemogenesis correlated strongly and significantly with the rate of substrate utilization by alcohol dehydrogenase. These results are consistent with the view that the reaction to primary alcohols applied topically to human skin is provoked, in large part, by the corresponding aldehyde

Energy cost associated with vortex crossing in superconductors

Starting from the Ginzburg-Landau free energy of a type II superconductor in a magnetic field we estimate the energy associated with two vortices crossing. The calculations are performed by assuming that we are in a part of the phase diagram where the lowest Landau level approximation is valid. We consider only two vortices but with two markedly different sets of boundary conditions: on a sphere and on a plane with quasi-periodic boundary conditions. We find that the answers are very similar suggesting that the energy is localised to the crossing point. The crossing energy is found to be field and temperature dependent -- with a value at the experimentally measured melting line of $U_\times \simeq 7.5 k T_m \simeq 1.16/c_L^2$, where $c_L$ is the Lindemann melting criterion parameter. The crossing energy is then used with an extension of the Marchetti, Nelson and Cates hydrodynamic theory to suggest an explanation of the recent transport experiments of Safar {{\em et al.}\ }.Comment: 15 pages, RevTex v3.0, followed by 5 postscript figure

Learning and digital inclusion: the ELAMP project

The Electronic Learning and Mobility Project (ELAMP) was a nationally funded project by the Department for Children, Schools and Families, which ran from 2004 to 2010. The main aim of ELAMP was to improve the education of Traveller children, particularly highly mobile learners. ELAMP focussed upon the use of mobile technology and distance learning to support, enhance and extend young Travellers’ educational and vocational opportunities. This article will reflect upon the learning and technological experiences and opportunities that the ELAMP project provided for Traveller children, young people and their families. In doing so it will critically consider the value of information technology in working with Traveller communities and advancing their educational opportunities. Reviewing ELAMP work will also demonstrate how the use of mobile technology can improve educational outcomes and Traveller families’ digital inclusion. Now that the project has ended, this article will question why we are not using what we learnt from ELAMP to move forward

Exact vortex nucleation and cooperative vortex tunneling in dilute BECs

With the imminent advent of mesoscopic rotating BECs in the lowest Landau level (LLL) regime, we explore LLL vortex nucleation. An exact many-body analysis is presented in a weakly elliptical trap for up to 400 particles. Striking non-mean field features are exposed at filling factors >>1 . Eg near the critical rotation frequency pairs of energy levels approach each other with exponential accuracy. A physical interpretation is provided by requantising a mean field theory, where 1/N plays the role of Planck's constant, revealing two vortices cooperatively tunneling between classically degenerate energy minima. The tunnel splitting variation is described in terms of frequency, particle number and ellipticity.Comment: 4 pages,4 figure