Assorted links

1. The economics of principal write-downs.

2. Saturn's Hyperion: a moon with odd craters, more astronomy photos here, via GH.

3. Different ways supermarkets increase their profit margins.

4. What economists know about open source software.

5. Peto's paradox: why is there no correlation between animal body size and cancer?, plus a meditation on blue whales.

6. The new Banerjee-Duflo book.

7. Reihan on Brink Lindsey and TGS.