Evaporative depolarization and spin transport in a unitary trapped Fermi gas

We consider a partially spin-polarized atomic Fermi gas in a high-aspect-ratio trap, with a flux of predominantly spin-up atoms exiting the center of the trap. We argue that such a scenario can be produced by evaporative cooling, and we find that it can result in a substantially non-equilibrium polarization pattern for typical experimental parameters. We offer this as a possible explanation for the quantitative discrepancies in recent experiments on spin-imbalanced unitary Fermi gases.Comment: 6 pages, 3 figures; published versio

Trimers, molecules and polarons in imbalanced atomic Fermi gases

We consider the ground state of a single "spin-down" impurity atom interacting attractively with a "spin-up" atomic Fermi gas. By constructing variational wave functions for polarons, molecules and trimers, we perform a detailed study of the transitions between each of these dressed bound states as a function of mass ratio $r=m_\uparrow/m_\downarrow$ and interaction strength. We find that the presence of a Fermi sea enhances the stability of the $p$-wave trimer, which can be viewed as a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) molecule that has bound an additional majority atom. For sufficiently large $r$, we find that the transitions lie outside the region of phase separation in imbalanced Fermi gases and should thus be observable in experiment, unlike the well-studied equal-mass case.Comment: 5 pages, 2 figure

Phase separation and collapse in Bose-Fermi mixtures with a Feshbach resonance

We consider a mixture of single-component bosonic and fermionic atoms with an interspecies interaction that is varied using a Feshbach resonance. By performing a mean-field analysis of a two-channel model, which describes both narrow and broad Feshbach resonances, we find an unexpectedly rich phase diagram at zero temperature: Bose-condensed and non-Bose-condensed phases form a variety of phase-separated states that are accompanied by both critical and tricritical points. We discuss the implications of our results for the experimentally observed collapse of Bose-Fermi mixtures on the attractive side of the Feshbach resonance, and we make predictions for future experiments on Bose-Fermi mixtures close to a Feshbach resonance.Comment: 7 pages, 3 figures. Extended versio

Insignia lowers wheat quality

Farmers in Western Australia have been advised not to plant Insignia wheat because it has poor grain quality. Many farmers want to know why Insignia is considered poor quality and what harm it could do. This article answers these questions and suggests alternative, better quality wheats for all present situations

Project management of an integrated iron and steelworks during design, planning and construction

Much has been said, and many papers written, on the technical design problems associated with all branches of engineering involved in the building of a multi-million pound integrated steel plant. The object of this paper is not to add to their number, but rather to highlight the executive and management problems which arise in the course of the development and construction of this type of plant

Experimental consequences of the s-wave cos(k(x))cos(k(y)) superconductivity in the iron pnictides

The experimental consequences of different order parameters in iron-based superconductors are theoretically analyzed. We consider both nodeless and nodal order parameters, with emphasis on the cos(k(x))cos(k(y)) nodeless order parameter recently derived by Seo [arXiv:0805.2958, Phys. Rev. Lett. (to be published)]. We analyze the effect of this order parameter on the spectral function, density of states, tunneling differential conductance, penetration depth, and the NMR spin-relaxation time. This extended s-wave symmetry has line zeros in between the electron and hole pockets, but they do not intersect the two Fermi surfaces for moderate doping, and the superconductor is fully gapped. However, this suggests several quantitative tests: the exponential decay of the penetration depth weakens and the density of states reveals a smaller gap upon electron or hole doping. Moreover, the cos(k(x))cos(k(y)) superconducting gap is largest on the smallest (hole) Fermi surface. For the 1/T-1 NMR spin-relaxation rate, the interband contribution is consistent with the current experimental results, including a (nonuniversal) T-3 behavior and the absence of a coherence peak. However, the intraband contribution is considerably larger than the interband contributions and still exhibits a small enhancement in the NMR spin-relaxation rate right below T-c in the clean limit

Simulation Studies of Nanomagnet-Based Architecture

We report a simulation study on interacting ensembles of Co nanomagnets that can perform basic logic operations and propagate logic signals, where the state variable is the magnetization direction. Dipole field coupling between individual nanomagnets drives the logic functionality of the ensemble and coordinated arrangements of the nanomagnets allow for the logic signal to propagate in a predictable way. Problems with the integrity of the logic signal arising from instabilities in the constituent magnetizations are solved by introducing a biaxial anisotropy term to the Gibbs magnetic free energy of each nanomagnet. The enhanced stability allows for more complex components of a logic architecture capable of random combinatorial logic, including horizontal wires, vertical wires, junctions, fanout nodes, and a novel universal logic gate. Our simulations define the focus of scaling trends in nanomagnet-based logic and provide estimates of the energy dissipation and time per nanomagnet reversal

Supersolidity in electron-hole bilayers with a large density imbalance

We consider an electron-hole bilayer in the limit of extreme density imbalance, where we have a single particle in one layer interacting attractively with a Fermi liquid in the other parallel layer. Using an appropriate variational wave function for the dressed exciton, we provide strong evidence for the existence of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase in electron-hole bilayers with a large density imbalance. Furthermore, within this unusual limit of FFLO, we find that a dilute gas of minority particles forms excitons that condense into a two-dimensional "supersolid".Comment: 6 pages, 2 figure

Metacarpophalangeal pattern profile analysis of a sample drawn from a North Wales population

This is tha author's PDF version of an article published in Annals of human biology© 2001. The definitive version is available at http://www.tandf.co.uk/journalsSexual dimorphism and population differences were investigated using metacarpophalangeal pattern profile (MCPP) analysis. Although it is an anthropmetric technique, MCPP analysis is more frequently used in genetic syndrome analysis and has been under-used in the study of human groups. The present analysis used a series of hand radiographics from Gwynedd, North Wales, to make comparisons, first, between the sexes within the sample and then with previously reported data from Japan. The Welsh sexes showed MCPP analyses that indicated size and shape differences but certain similarities in shape were also evident. Differences with the Japanese data were more marked. MCPP anlysis is a potentially useful anthropmetric technique but requires further statistical development