May 30, 2010
This may be of interest:
SCHOOL OF PHYSICS COLLOQUIUM
Monday 31st May, 2010 at 3:15 pm
refreshments from 3pm
Venue: Slade Lecture Theatre, School of Physics
Title: The multi-scale physics of aurorae
Presenter: Dr C.C. Chaston
University of California at Berkeley
The Earthward acceleration of electrons which powers the emission auroral light is a consequence of large scale processes in the Earth’s magnetosphere. However this acceleration occurs in electromagnetic fields with small scale sizes. In this presentation we explore the physics of how energy is transported across scales in the auroral acceleration region to facilitate particle acceleration, and show how cross-scale energy transport ultimately leads to the formation of the rapidly kinking, curling and folding light displays that make watching the aurora so compelling.
In pursuing this goal we exploit simulations and recent high resolution observations from space borne and ground based cameras along with plasma measurements from a number of polar orbiting spacecraft. Together these methods indicate that the motion and structuring of auroral forms is a manifestation of the action of well known plasma instabilities common in many space and astrophysical plasma environments. These instabilities launch an Alfven wave cascade toward smaller scales through the auroral acceleration region to form finely structured bright auroral forms and drive auroral plasmas toward a turbulent state. The universality of this kind of process in high Reynolds number plasmas means that the auroral acceleration region is a easily accessible laboratory for the study of energy transport and conversion in space with relevance to a wide range of space and astrophysical plasma contexts.
May 28, 2010
I’ve just come across MathOnline, a free resource:
…where you can find and collect your mathematical resources. Books, lecture notes, survey articles and more are all welcome.
I would have loved this when doing my PhD. The Course in Universal Algebra brought back memories.
May 15, 2010
In Greg Sheridan’s piece Cameron has chance to make UK great again in today’s Australian he made an astonishing factual error. An error that, amazingly enough, wasn’t picked up before the piece was published in print and online.
Greg writes that Scotland has 99 seats in the 650 member UK House of Commons – a much larger share of the House of Commons than it would have if seats were allocated to Scotland, England, Wales and Northern Island on the basis of their relative populations. (Wales is also over-represented.) He writes that Scotland, and to a lesser extent Wales, live as “socialist dependencies and overwhelmingly vote Labour”.
Of course, Scotland only has 59 seats in the House of Commons, as any political junkie knows. There have been 59 Scottish seats since the 2005 election, down from the previous 72. Greg Sheridan may have mixed up his knowledge that Scotland had been over-represented – an easy error – but one that should have been picked up before publication.
It’s true that Scotland and Wales are over-represented in the House of Commons on the basis of UK Govt population estimates for mid-2008 – Scotland would have 55 seats and Wales 32, instead of the 59 and 40 they actually have. Northern Island would have 19 instead of the actual 18. But this is a much smaller overrepresentation (total of 12 seats) than Greg writes about.
While Greg’s error is relatively minor and doesn’t detract from his core argument, its obviousness may make a reader question how substantial his writing is. Pretty poor for a “serious” journalist.