Report from SIAM DS 2007 May 28 - June 1, 2007 Snowbird, Utah Written by Luz V. Vela-Arevalo (Georgia Tech, Atlanta)

The 2007 SIAM Conference on Applications of Dynamical Systems took place again at Snowbird, Utah, on May 28 to June 1. It all started on Sunday May 27 with the arrival of many of the 720 participants of this conference. The usual stories about lost suitcases (wallets in some cases) and chatting between old or new friends almost immediately turned into science discussions. This is the kind of conference where people take any opportunity to be engaged in science. One such opportunity was the welcoming reception at the patio of the Cliff Lodge, where one could also get a taste of Utah's Polygamous Porter (beer). During the following days the conference would provide multiple opportunities to discuss science, problems, career moves, and also to catch up with friends and meet new people.

Conference participants at the Welcome Reception on Sunday May 27, 2007; photographs by Susan Whitehouse, SIAM Membership Manager.

On Monday May 28 at 8:15 am, you could feel the activity intensifying at the more than 10 concurrent sessions, with people locating rooms for the minisymposia and some still trying to get a quick breakfast. I attended the session on complex networks, where, surprisingly, the projector worked well with PC's but not with Mac's. I learnt that the 108th House in the USA Congress (2003-4) has been the worst in terms of people voting along with their parties without talking to each other, and this conclusion came from sparse network rating systems by Mason Porter (Caltech). Data assimilation was my next topic of choice, and Istvan Szunyogh (University of Maryland) spoke about feedback between error growth and accuracy of initial conditions in weather prediction.

At the first invited presentation, the mentioning of the organizing committee took place: Sue Ann Campbell (co-chair, University of Waterloo), Arjen Doelman (University of Amsterdam), Jinqiao Duan (Illinois Institute of Technology), Alain Goriely (University of Arizona), Aric Hagberg (Los Alamos National Laboratory), Bernd Krauskopf (co-chair, University of Bristol), Mary Silber (Northwestern University, and Mary Lou Zeeman (Bowdoin College). Following the opening remarks, Ed Ott (University of Maryland) introduced Hans Hermann from ETH Zürich, who gave a very interesting talk about the motion of dunes. Definition: a dune is a trap of sand grains made by sand grains. After describing the models for different types of dunes, he showed simulations of the Barchan dunes that replicate dunes found on the South Pole of Mars.

For lunch, the obvious choices were the sandwiches in the hotel lobby, and the burrito buffet at El Chanate. The latter was my choice since I am Mexican, although burritos are hardly found in Mexico. Snowbird has more eating options, like the made-to-order sandwiches at the grocery store, a pizza place, and some other restaurants.

Monday afternoon's invited presentation was by Francisco Valero-Cuevas (Cornell University), who provided an excellent talk on the complexity of the brain-hand system. He described the anatomy of the hand and the analysis of redundant muscles. There were two blocks of concurrent sessions on Monday afternoon. I attended a session about some celestial mechanics problems, where the restricted three body problem was the subject of Gareth Roberts' work (College of the Holy Cross) about Saari's conjecture, and Shane Ross's (Virginia Polytechnic Institute and State University) about a mapping in the kicked problem. Then I headed for a session about signal processing applications such as epileptic seizure analysis, food web reconstruction, and detection of damaged structures. I also could catch part of the session on recurrences.
		Francisco Valero-Cuevas, Cornell University; photograph by Hinke Osinga.

		Monday was a long day, since in the evening there was the award session and the Jürgen Moser Lecture. Martin Golubitsky (SIAM Past President) presented the Ralph E. Kleinman Prize to Salvatore Torquato from Princeton University, for bringing together applied and pure mathematics, chemistry and modelling. The J.D. Crawford Prize was presented to Andrew Stuart from the University of Warwick for his studies of conditional sampling in stochastic PDEs. The Jürgen Moser Lecture Prize was awarded to Harry L. Swinney from the University of Texas at Austin. In his lecture he showed that the ozone hole is persistent due to KAM tori forming a barrier in the atmospheric circulation at the South Pole.
Harry Swinney (University of Texas at Austin) and John Guckenheimer (Cornell University); photograph by Hinke Osinga.

Early Tuesday morning I was a couple of minutes late for Steve Strogatz' talk (Cornell University) on chimera states, and the room could not fit one more person! It was not a regretful situation, however, because I attended the talk by Eric Kostelich (Arizona State University) about estimation of model error in weather forecasting. In the same session, Evelyn Sander (George Mason University) spoke about classifications of explosions, and there was a talk about economic models.

The invited talk of Tuesday morning was by Peter Imkeller from Humboldt University about large stochastic resonance and Levy noise induced transitions, who analized how different noise regimes give different results in Gaussian stochastic differential equations motivated by climate dynamics. After the lunch break, the invited presentation was by Jane Wang from Cornell University about the physics of insect flight and falling paper. She presented experimental and modelling work on tumbling and fluttering motions.
		Mary Silber (Northwestern University), Jane Wang (Cornell University) and Rachel Kuske (University of British Columbia); photograph by Susan Whitehouse, SIAM Membership Manager.

The Association for Women in Mathematics (AWM) Workshop was part of this year's conference. The participants of the workshop were young women such as students or recent PhD's starting a career in mathematics, who were selected and partially funded by the AWM; I had the chance to be one of them. Mary Lou Zeeman and Mary Silber organized the workshop. Each of the participants was paired with a female academic as a mentor, and we all attended a dinner on Tuesday night at The Summit restaurant. We had the chance to meet with each other and to know first hand the background and experiences of successful women with varied careers in different fields of mathematics. We all introduced ourselves and prepared the mood for the workshop taking place next day.

		On Wednesday morning the first session of the AWM workshop was about dynamical systems and applications to mathematical biology. This session was attended by the participants of the workshop and by many others at the conference. The subjects were dynamic synapses, biochemical reaction networks, infinite population genetic algorithms, and stability in nonlinear discrete models.
Maya Mincheva (University of Wisconsin, Madison), Mihaela Predescu (Bentley College), Christina Hayes (Gettysburg College), and Anne Catlla (Duke University); courtesy of AWM.

The invited presentation of Wednesday morning was hosted by Philip Holmes, who introduced Ian Couzin from the University of Oxford. His talk about collective animal behavior and decision making presented theory, field experiments and simulations in his integrative approach to explain ant traffic, motion of school of fish, collective memory and locusts behaviour. I remember his movie of bugs going in circles and biting each other in the back as to correct their course, and also his T-shirt with the slogan "Hecho en California."

The AWM-SIAM Sonia Kovalevsky Prize and Lecture was awarded to Lai-Sang Young (Courant Institute) for her work on shear induced chaos, which was the topic of the afternoon invited presentation. The activities of the AWM Workshop continued with a discussion panel on "Shaping your career in mathematics." The panel included Barbara Lee Keyfitz from The Fields Institute and the University of Houston, Deborah Lockhard from NSF, Gerda de Vries from the University of Alberta, and Emily F. Stone from the University of Montana. The panellists opened the discussion with their own experiences in building a career in mathematics, and provided their insight and advice on what female mathematicians face in their career: research is the key in this career, the quality of research is what buys a position; a postdoc is a convenient step towards an academic position, rather than going directly from PhD to a faculty position; searching for opportunities wherever you might find
		Lai-Sang Young (Courant Institute); photograph by Hinke Osinga.
them, such as travel grants of the AWM; decide the life you want to have, what works for you, including planning of children, commuting, etc.; take charge of your own professional development; enhance communication skills for interviews, papers, grant proposals; maintain a balanced life, not all can be work; academic positions offer flexibility that a woman can take advantage of for things like a family; take yourself seriously, be responsible. The general discussion versed on one recurrent topic: how to plan an academic career at the same time as a family, especially about what is a good time to have children, since there is still a general feeling that your career stops for raising kids. Since this is not necessarily the case, there was no conclusion about this topic, there is no better time for having kids, one has to make an individual decision and do what is best for oneself. Many institutions are now more flexible about it and it is a case-by-case scenario. Another point that was raised is that there is not just one model of an academic career in mathematics, besides a faculty position in a university, there are other options such as the national labs, college positions, NSF positions, etc.

The AWM workshop continued in the afternoon of Wednesday, with a session about PDEs and physical systems. My talk was first in this block and it was on quantum coherent states for the hydrogen atom. There were also talks on rotational Stokes waves, travelling waves in the Ginzburg-Landau equation and pattern formation in Rayleigh-Bénard convection.
		Vera Hur (MIT), Janet Scheel (California Lutheran University), Luz Vela-Aravelo (Georgia Tech), and Claire Postlethwaite (Northwestern University); courtesy of AWM.

		The poster session on Wednesday night was as successful as the sweets and desserts offered to the attendees. I had the chance to chat with participants of the AWM workshop who presented posters, but also I had a look at many posters on different topics. I heard about processing of odors with network models, integrals in celestial mechanics, mixing in hurricanes, breakdown of WKB, and travelling waves in flame propagation.
Hinke Osinga (University of Bristol) with her AWM mentee Elizabeth Zollinger (Boston University); photograph by Susan Whitehouse, SIAM Membership Manager.

Thursday was the last day for me, and since I was done with my talk, I could be more relaxed. I woke up to attend the minisymposium about uncertainty propagation in dynamical systems. Instead of a talk, the last section was reserved for discussion, and one point mentioned was that uncertainty can work for you or against you, and the dynamical systems community needs to embrace this.

The invited presentation for Thursday morning was by George Haller from MIT, about aerodynamic separation and invariant manifolds. He promised not to speak about finite-time Lyapunov exponents --- in my choice of talks during the conference, this was probably the most recurrent phrase. He showed simulations, theory and experiments. Before this talk there was an award ceremony for the winners of the DSWeb Tutorials Competition, and for the winners of the `red sock' awards for the best posters.

Jim Yorke (University of Maryland) with red sock award winners Daniele Avitabile (University of Surrey), Alethea Barbaro (UC Santa Barbara) and Marshall Hampton (University of Minnesota, Duluth). Other winners were Jo Mason (University of Bristol), shown on the right with her poster, and Jue Wang (University of Wisconsin, Madison); photographs by Hinke Osinga.

During lunch time on Thursday I took time off and went for a ride in the aerial tram. The tram goes from 8000 ft at its base, to 11000 ft at the top of Hidden Peak. There was a lot of snow and we were told it was still possible to ski.

The invited presentation in the afternoon was by Natalia Komarova from the University of California, Irvine, about modelling of cancer. Afterwards, I attended a session on different approaches to the swimming of fish: approximation of vortices by the average of two fish swimming in parallel; control of robotic fish, with movies of a robot swimming in a pool; Lagrangian coherent structures in fish and jellyfish motion; a complete Navier-Stokes study of three fish and the effect of vortices; and free-body motion in the presence of a potential jet and oscillation of a nearby body. For me this was the end of the 2007 SIAM Dynamical Systems conference, although activities continued on Friday.

Co-chairs Bernd Krauskopf (University of Bristol) and Sue Ann Campbell (University of Waterloo) celebrate a successful Snowbird 2007; photograph by Hinke Osinga.