The Mars rover Spirit encountered outcrops and regolith composed of opaline silica (amorphous SiO2·nH2O) in an ancient volcanic hydrothermal setting in Gusev crater. An origin via either fumarole-related acid-sulfate leaching or precipitation from hot spring fluids was suggested previously. However, the potential significance of the characteristic nodular and mm-scale digitate opaline silica st...

Prepared for the Journal of Economic Perspectives. The authors would like to thank David Pennock, Emile Servan-Schreiber of NewsFutures, David Dempsey and John Delaney of Tradesports, Alison Fealey and Oliver Frankel of Goldman Sachs, and George Neumann of IEM for help with data. Thanks to Kay-Yut Chen, Robin Hanson, Jim Hines, Andrew Leigh, Betsey Stevenson, Timothy Taylor, Hal Varian, Michael...

We propose a semiparametric modeling approach for mixtures of symmetric distributions. The mixture model is built from a common symmetric density with different components arising through different location parameters. This structure ensures identifiability for mixture components, which is a key feature of the model as it allows applications to settings where primary interest is inference for t...

ABSTRACT Red Geysers are quiescent galaxies with galactic scale ionized outflows, likely due to low-luminosity active nuclei (AGN). We used Gemini GMOS-IFU observations of the inner ∼1–3 kpc nine selected from MaNGA survey study gas ionization and kinematics. The emission-line ratios suggest presence Seyfert/LINER (Low Ionization Nuclear Emission Region) in all sources. Two show Hα equivalent w...

We study cool neutral gas traced by NaD absorption in 140 local ($\rm z<0.1)$ early-type ``red geyser'' galaxies. These galaxies show unique signatures spatially-resolved strong-line emission maps that have been interpreted as large-scale active galactic nuclei driven ionized winds. To investigate the possible fuel source for these winds, we examine abundance and kinematics of T \sim 100-1000 K...