Motion and homogenization of vortices in anisotropic Type II superconductors

The motion of vortices in an anisotropic superconductor is considered. For a system of well-separated vortices, each vortex is found to obey a law of motion analogous to the local induction approximation, in which velocity of the vortex depends upon the local curvature and orientation. A system of closely packed vortices is then considered, and a mean field model is formulated in which the individual vortex lines are replaced by a vortex density

Electrochemical Energy Storage Subsystems Study, Volume 2

The effects on life cycle costs (LCC) of major design and performance technology parameters for multi kW LEO and GEO energy storage subsystems using NiCd and NiH2 batteries and fuel cell/electrolysis cell devices were examined. Design, performance and LCC dynamic models are developed based on mission and system/subsystem requirements and existing or derived physical and cost data relationships. The models are exercised to define baseline designs and costs. Then the major design and performance parameters are each varied to determine their influence on LCC around the baseline values

Electrochemical energy storage subsystems study, volume 1

The effects on life cycle costs (LCC) of major design and performance technology parameters for multi kW LEO and GEO energy storage subsystems using NiCd and NiH2 batteries and fuel cell/electrolysis cell devices were examined. Design, performance and LCC dynamic models are developed based on mission and system/subsystem requirements and existing or derived physical and cost data relationships. The models define baseline designs and costs. The major design and performance parameters are each varied to determine their influence on LCC around the baseline values

Moisture in Molasses as a Factor in the Heating of Feeds.

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Theory of pattern-formation of metallic microparticles in poorly conducting liquid

We develop continuum theory of self-assembly and pattern formation in metallic microparticles immersed in a poorly conducting liquid in DC electric field. The theory is formulated in terms of two conservation laws for the densities of immobile particles (precipitate) and bouncing particles (gas) coupled to the Navier-Stokes equation for the liquid. This theory successfully reproduces correct topology of the phase diagram and primary patterns observed in the experiment [Sapozhnikov et al, Phys. Rev. Lett. v. 90, 114301 (2003)]: static crystals and honeycombs and dynamic pulsating rings and rotating multi-petal vortices.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let

Motion of vortices in type II superconductors

The methods of formal asymptotics are used to examine the behaviour of a system of curvilinear vortices in a type II superconductor as the thickness of the vortex cores tends to zero. The vortices then appear as singularities in the field equation and are analagous to line vortices in inviscid hydrodynamics. A local analysis near each vortex core gives an equation of motion governing the evolution of these singularities

Reaction Diffusion and Ballistic Annihilation Near an Impenetrable Boundary

The behavior of the single-species reaction process $A+A\to O$ is examined near an impenetrable boundary, representing the flask containing the reactants. Two types of dynamics are considered for the reactants: diffusive and ballistic propagation. It is shown that the effect of the boundary is quite different in both cases: diffusion-reaction leads to a density excess, whereas ballistic annihilation exhibits a density deficit, and in both cases the effect is not localized at the boundary but penetrates into the system. The field-theoretic renormalization group is used to obtain the universal properties of the density excess in two dimensions and below for the reaction-diffusion system. In one dimension the excess decays with the same exponent as the bulk and is found by an exact solution. In two dimensions the excess is marginally less relevant than the bulk decay and the density profile is again found exactly for late times from the RG-improved field theory. The results obtained for the diffusive case are relevant for Mg$^{2+}$ or Cd$^{2+}$ doping in the TMMC crystal's exciton coalescence process and also imply a surprising result for the dynamic magnetization in the critical one-dimensional Ising model with a fixed spin. For the case of ballistic reactants, a model is introduced and solved exactly in one dimension. The density-deficit profile is obtained, as is the density of left and right moving reactants near the impenetrable boundary.Comment: to appear in J. Phys.

Being a peer support mentor for individuals who have had a lower limb amputation:an interpretative phenomenological analysis

Purpose: Although peer support has received research attention within different health related contexts, there is limited research considering individuals who have experienced an amputation. In particular, the peer mentoring role is under-explored. Therefore, this research aimed to explore the experiences of participants delivering peer support interventions to individuals with lower limb loss. Methods: Eight people who acted as peer mentors for people with limb loss took part in semi-structured interviews. Data were analyzed using Interpretative Phenomenological Analysis (IPA). Results: Two overarching themes were identified from the data: “Developing a Helpful Self”, in which the personal value and meaning of being a peer mentor is presented, and “Connecting with Vulnerability”, which addresses the emotional challenges of peer mentoring and the impact of these on wellbeing. Conclusions: Findings suggest positive experiences of providing support, including increased hope, resilience and a sense of belonging and connection to others. However, peer mentors experienced challenges related to uncertainty and doubt about their mentoring abilities and with developing and maintaining resilience in the role. Recommendations include the development of training packages and increased clarity for volunteers of the peer mentor role.Implications for rehabilitation It is important to define clearly the role of a peer mentor and the responsibilities this involves. Peer mentors should be provided with support and training to increase their confidence and ability to act appropriately when encountering distress. It is important to provide transparent guidelines and procedures to support peer mentors to minimize concerns over risk and safety. Feedback regarding how effective the support offered is and how it could be improved should be provided

On the exactly solvable pairing models for bosons

We propose the new exactly solvable model for bosons corresponding to the attractive pairing interaction. Using the electrostatic analogy, the solution of this model in thermodynamic limit is found. The transition from the superfluid phase with the Bose condensate and the Bogoliubov - type spectrum of excitations in the weak coupling regime to the incompressible phase with the gap in the excitation spectrum in the strong coupling regime is observed.Comment: 19 page

Diffusion and dispersion of passive tracers: Navier-Stokes versus MHD turbulence

A comparison of turbulent diffusion and pair-dispersion in homogeneous, macroscopically isotropic Navier-Stokes (NS) and nonhelical magnetohydrodynamic (MHD) turbulence based on high-resolution direct numerical simulations is presented. Significant differences between MHD and NS systems are observed in the pair-dispersion properties, in particular a strong reduction of the separation velocity in MHD turbulence as compared to the NS case. It is shown that in MHD turbulence the average pair-dispersion is slowed down for $\tau_\mathrm{d}\lesssim t\lesssim 10 \tau_\mathrm{d}$, $\tau_\mathrm{d}$ being the Kolmogorov time, due to the alignment of the relative Lagrangian tracer velocity with the local magnetic field. Significant differences in turbulent single-particle diffusion in NS and MHD turbulence are not detected. The fluid particle trajectories in the vicinity of the smallest dissipative structures are found to be characterisically different although these comparably rare events have a negligible influence on the statistics investigated in this work.Comment: Europhysics Letters, in prin