## Tiny tiny origami

My Christmas reading has included a PhD* thesis, I am external examiner for a student at Oxford, and the viva is mid-January. The thesis is on the computer simulations of a model of DNA. The simulations are of what is called DNA origami. Origami is of course folding up a sheet of paper in a precise way, to make a paper plane, paper flower, etc.

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## Direct from the Sun

As a scientist I guess I should stop and admire the beautiful natural world a bit more than I do. Too busy doing stuff most of the time, which is a poor excuse. Anyway, above is a picture of sunset over the river Seine in Paris. To the right you can see twin squarish towers, this is I think the Notre Dame cathedral.

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## Climate change

On Tuesday I went to one of the general evening physics run by the local group of the Institute of Physics, mainly Paul Stevenson and others on the committee. Future talks here. It was on climate change and the figure that really stood out for me in the talk is above. It is taken from the newly released physical science bit of the 5th report of the IPCC (Intergovernmental Panel on Climate Change). Basically it shows the temperature averaged over the whole of the Earth and over a decade of time, as a function of time. I.e., the average temperature in the 1980s, in the 1990s, etc. The y-axis is in ÂșC and is I think the difference in temperature in a decade relative to the average temperature between 1961 and 1990.

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## Ducklings demonstrating superposition

Semester 2 starts on Monday, so I’m revising my lecture notes for my course on partial differential equations. This includes what is called the principle of superposition, which underlies what we know as the interference of waves. This picture (from a user called Spiralz on Wikimedia) shows interference off beautifully. Perhaps this is clearest on the left at about the same height as the ducklings, where the waves set up by the rear duckling intefers with that of its mother to produce a cross-hatched appearance on the water surface due to the addition (superposition) of the two waves going in different directions at that point. Beautiful physics, cute ducklings, what’s not to like.