Comma Butterfly

A comma butterfly (Polygonia c-album), so-called because of the little white C-shape or 'comma' on the underside of its wings ('c-album' being Latin for 'white-C').  Photos take in Reading University grounds, Reading, UK, on 2008-09-21.

Butterflies of this species that hatch early in the summer and which will breed and die in the same year, tend to have lighter underwings.  Those, like this one, which hatch later in the summer and which overwinter and breed the following year, tend to have darker underwings.

End of Season Hoverfly

A hoverfly; I have no idea of its genus, never mind the species.  There are around 250 species of hoverfly in Britain and the insect guides I have only cover a dozen or so between them.  Photo taken in Reading University grounds, Reading, UK, on 2008-09-20.

Scorpion Fly

A female scorpion fly of the genus Panorpa.  Photos taken in Reading University grounds, Reading, UK on 2008-09-20.  Male scorpion flies have rather imposing scorpion-like stings at the end of their tail.  I cannot recall ever having seen one of these flies before.  This one was spotted by my daughter Zoe, but I took the photos.

The Pfaffian in the Grassmannian...

From a post by David Guarrera at Imaginary Potential:

One example that I do understand, since I’ve read the paper many times, is Hori and Tong’s “proof” of Rodland’s Conjecture: that the Pfaffian in the Grassmannian G(2,7) lives on the same kahler moduli space as a hypersurface Calabi Yau in a Grassmannian. The proof uses beautiful physical intuition about the dynamics of non-abelian gauge theories in two dimensions.

However, you may think that the kahler moduli spaces of Calabi Yau’s are useless. Fair enough, I say. But they’re quite beautiful.

Pre-Columbian Mountaineering

From Wikipedia page on World Altitude Records (mountaineering):

European exploration of the Himalaya began in earnest during the mid-19th century, and the earliest people known to have climbed in the range were surveyors of the Great Trigonometric Survey. During the 1850s and 1860s they climbed dozens of peaks of over 6,100 m (20,000 ft) and several of over 6,400 m (21,000 ft) in order to make observations, and it was during this period that claims to have ascended the highest point yet reached by man began to be made.

Most of these early claims have now been rendered redundant by the discovery of the bodies of three children at the 6,739 m (22,110 ft) summit of Llullaillaco in South America: Inca sacrifices dated to around AD 1500.  There is no direct evidence that the Incas reached higher points, but the discovery of the skeleton of a guanaco on the summit ridge of Aconcagua (6,962 m, 22,841 ft) suggests that they also climbed on that mountain, and the possibility of Pre-Columbian ascents of South America's highest peak cannot be ruled out.