Vortices and dynamics in trapped Bose-Einstein condensates

I review the basic physics of ultracold dilute trapped atomic gases, with emphasis on Bose-Einstein condensation and quantized vortices. The hydrodynamic form of the Gross-Pitaevskii equation (a nonlinear Schr{\"o}dinger equation) illuminates the role of the density and the quantum-mechanical phase. One unique feature of these experimental systems is the opportunity to study the dynamics of vortices in real time, in contrast to typical experiments on superfluid $^4$He. I discuss three specific examples (precession of single vortices, motion of vortex dipoles, and Tkachenko oscillations of a vortex array). Other unusual features include the study of quantum turbulence and the behavior for rapid rotation, when the vortices form dense regular arrays. Ultimately, the system is predicted to make a quantum phase transition to various highly correlated many-body states (analogous to bosonic quantum Hall states) that are not superfluid and do not have condensate wave functions. At present, this transition remains elusive. Conceivably, laser-induced synthetic vector potentials can serve to reach this intriguing phase transition.Comment: Accepted for publication in Journal of Low Temperature Physics, conference proceedings: Symposia on Superfluids under Rotation (Lammi, Finland, April 2010

Is the writing on the wall for tabletops?

We describe an ethnographic study that explores how low tech and new tech surfaces support participation and collaboration during a workshop breakout session. The low tech surfaces were post-it notes and large sheets of paper. The new tech surfaces were writeable walls and a multi-touch tabletop. Four groups used the different surfaces during three phases: i) brief presentation of position papers and discussion of themes, ii) the creation of a group presentation and iii) a report back session. Participation and collaboration varied depending on the physical, technological and social factors at play when using the different surfaces. We discuss why this is the case, noting how new shareable surfaces may need to be constrained to invite participation in ways that are simply taken for granted because of their familiarity when using low tech materials

Brain damage in fatal non-missile head injury in relation to age and type of injury

Brain damage in a series of 635 fatal non-missile head injuries has been analysed with particular reference to the age of the patient and the type of injury. The differences in the type of brain damage in relation to age were less than we had anticipated, lending further support to the contention that the aged brain has a reduced potential for recovery. The analysis confirms the relationship between road traffic accidents, diffuse axonal injury, gliding contusions and 'basal ganglia' haematomas, and the importance of diffuse brain swelling resulting from a head injury in children

Brain damage in fatal non-missile head injury in relation to age and type of injury

Brain damage in a series of 635 fatal non-missile head injuries has been analysed with particular reference to the age of the patient and the type of injury. The differences in the type of brain damage in relation to age were less than we had anticipated, lending further support to the contention that the aged brain has a reduced potential for recovery. The analysis confirms the relationship between road traffic accidents, diffuse axonal injury, gliding contusions and 'basal ganglia' haematomas, and the importance of diffuse brain swelling resulting from a head injury in children