Jasper Hasenkamp (NYU) gave the brown-bag, about fixing anomalies between large-scale-structure cosmology results and cosmic-microwave-background cosmology results using mixed dark matter—the standard CDM model plus a small admixture of a (possibly partially thermalized) neutrino-like species. The model seems to work well and will make new predictions, including (in principle) for accelerator experiments. Mark Wyman (NYU) has also worked on similar things.

At the "No More Tears" phone-con (about Kepler planet-searching), we talked about wavelets with Bekki Dawson (Berkeley) and other exoSAMSI participants. In our MCMC meeting, we worked on finishing Hou's nearly finished paper on nested sampling, and we quizzed Goodman about mixing the stretch move (the underlying engine of emcee) with Metropolis-Hastings to capitalize on the observation that in most likelihood functions there are "fast" and "slow" parameters, where the "fast" parameters can be changed and the likelihood call re-made quickly, while the "slow" parameters require some large, expensive re-calculation. This is generic, and we came up with some generic solutions. Some of them are even permitted mathematically. Foreman-Mackey is thinking about these in the context of running n-body simulations within the inference loop

In other news, Lang delivered a draft paper about his work on the WISE imaging, and Fadely had some ideas about finding nails for our factor-analysis hammer.

1 comment:

  1. Radford Neal has a few out-there ideas about fast and slow variables. You've probably seen them already, but I thought I'd mention it in case you haven't. I tried one a while back and it didn't help as much as I had hoped. I think it's good if some of the variables are *drastically* slower than the others. If it's marginal, don't bother.