As storage costs drop, storage is becoming the lowest cost in a digital repository – and the biggest risk. We examine current modelling of costs and risks in digital preservation, concentrating on the Total Cost of Risk when using digital storage systems for preserving audiovisual material. We present a managed approach to preservation, and the vital role of storage and show how planning for lo...

We have analysed near-infrared NTT/SofI observations of the starburst cluster Westerlund 1, which is among the most massive young clusters in the Milky Way. A comparison of colour-magnitude diagrams with theoretical main-sequence and pre-main sequence evolutionary tracks yields improved extinction and distance estimates of AKs = 1.13 ± 0.03 mag and d = 3.55 ± 0.17 kpc (DM = 12.75 ± 0.10 mag). T...

An error in the program for verifying the Ankeny-Artin-Chowla (AAC) conjecture is reported. As a result, in the case of primes p which are ≡ 5 mod 8, the AAC conjecture has been verified using a different multiple of the regulator of the quadratic field Q(√p) than was meant. However, since any multiple of this regulator is suitable for this purpose, provided that it is smaller than 8p, the main...