Back in the fall of 2003 I spent my first sabbatical leave at the Institute for Pure and Applied Mathematics (IPAM) at UCLA. From a professional perspective, the trip was very successful- I was able to wrap work on the first edition of a textbook that I was coauthoring, I learned a lot of new stuff about inverse problems (the topic of that long program at IPAM), and I made a lot of contacts that have been helpful in my research,
At a more personal level, that trip was extremely stressful, missing Sue (I was paying $0.15 per minute for cell phone calls), financial issues ($2,500 per month in rent was an enormous amount of money at the time, even if I would eventually get reimbursed for it...), and the general stress of living an unhealthy lifestyle in an incredibly stressful environment. Among other issues, that fall included no car (I'd flown to LA), a transit workers strike (making it impossible for me to get around town), a grocery store workers strike (picket lines at the one grocery store in Westwood village), and massive brush fires that left the city shrouded in smoke for several months. I remember thinking as I left town that I never wanted to return.
Once again I'm here at UCLA on sabbatical leave. So, why did I come back?
This time the theme of the semester long program is optimization, including several topics that are of particular interest to me (sparse optimization, efficient first order methods for structured convex optimization problems, and applications of semidefinite programming and conic optimization.) In addition to spending the semester learning about this exciting research, I'm planning to spend much of my time finishing up the data analysis for a project in cosmogenic nuclide dating that I've been working on for the last 5 years. I'm also working on the manuscript of the second edition of our inverse problems book, which is due at the publishers in December. There are a couple of other smaller research projects that I'd like to finish while I'm here. Professionally, I expect this trip to be at least as positive as my first trip to LA.
As Sue and I were driving across the Mojave desert last weekend, I thought about the personal aspect- in many ways my last visit to LA was very depressing, but I've changed dramatically since then. It's probably a good thing that I've taken myself out of my normal comfort zone. While I'm in this stressful environment, taking care of myself, physically, mentally, and emotionally will be a challenge, but I think I'm more capable of doing that than I was seven years ago.