# Faculty News Briefs

### November 2008

On October 2, 2008 Professor Tom Braden gave a colloquium at Reed College entitled *The Geometry of Bar-and-Joint Machines.*

On November 1, 2008 Professor Markos Katsoulakis attended the workshop on Scientific Challenges in Solar Energy Conversion and Storage, which was held at the Institute for Mathematics and Its Applications in Minneapolis, MN. He also gave an invited talk at the Mathematical Biosciences Institute workshop on Multiscale Methods in Biology held during the period November 2ñ4, 2008.

Professor Michael Lavine gave the following six talks during October: *What Is Bayesian Statistics and Why Everything Else Is Wrong?* at Haverford College; *Spike Trains and Human Brains* at Haverford College and Smith College; and *State Space Models for Optical Images of the Brain During Surgery* at Penn State University, University of Pennsylvania, and Virginia Tech. Professor Lavine was a Distinguished Visitor at Haverford College.

Professor Eyal Markman and Professor Jenia Tevelev organized a Special Session on Algebraic Geometry during the AMS 2008 Fall Eastern Section Meeting in Wesleyan University in Middletown, CT, which took place October 11ñ12, 2008. They had an excellent line-up of speakers giving one-hour talks on current trends in algebraic geometry. The speakers included UMass postdocs Sukhendu Mehrotra and Giancarlo Urzua. The titles of their talks were *Deformations of Fourier-Mukai Equivalences* (Mehrotra) and *Simply Connected Random Surfaces* (Urzua). Eyal Markman gave a talk entitled *Modular Galois Covers Associated to Symplectic Resolutions of Singularities.* The full program with abstracts is available at http://www.ams.org/amsmtgs/2154_program_ss1.html.

During the period October 14ñ17, 2008 Professor Nathaniel Whitaker participated in a panel at a conference at the Mathematical Sciences Research Institute in Berkeley, CA. The panel was entitled *Promoting Diversity at the Graduate Level in Mathematics: a National Forum.*

On October 15, 2008 Professor Emeritus Floyd Williams addressed two sixth grades classes at the STEM Middle Academy in Springfield, MA; STEM stands for Science, Technology, Engineering and Mathematics. This new school, which consists of 100 students, all of them sixth graders, has been heavily advertised on television. In his address Floyd spoke to about half the students in the school as well as teachers regarding careers in science and mathematics, applications of science and mathematics to everyday life, and the development of good study habits. He also entertained a wide range of questions.

On October 24, 2008 Professor HongKun Zhang gave a 45-minute talk at the Semi-Annual Workshop in Dynamical Systems and Related Topics at Penn State University. Her talk was entitled *Decay of Correlations for Hyperbolic Systems with Singularities.*

### October 2008

Professor Paul Gunnells attended the workshop *Number Theory and Physics at the Crossroads,* which took place September 21ñ26, 2008 at the Banff International Research Station in Banff, Alberta, Canada. He gave a talk entitled *Weyl Group Multiple Dirichlet Series.*

Professor Emeritus Jim Humphreys gave one of three short courses, which were presented September 15ñ19, 2008 at the University of Birmingham in the U.K. under the auspices of LMS-EPSRC. The overall theme was *Algebraic Groups and Related Topics,* and Jimís lectures were entitled *Modular Representations of Lie Algebras.* Students came from universities in the U.K. and elsewhere in the European Union. Further information is available at http://web.mat.bham.ac.uk/S.M.Goodwin/shortcourse/.

Professor Markos Katsoulakis is an invited speaker at the conference *Stochastic Differential Equations: Models and Numerics,* which will be held October 20ñ22, 2008 in Stockholm, Sweden at the Royal Institute of Technology.

### September 2008

During the period July 21ñ26, 2008 Professor Eduardo Cattani attended the conference on *Algebraic Geometry, D-modules, Foliations and Their Interactions,* which was held in Buenos Aires, Argentina. At the conference he gave a plenary talk entitled *Mixed Lefschetz Theorems and Hodge-Riemann Bilinear Relations: Geometry and Combinatorics.*

Professor Emeritus Edward Connors was named chair of the Karl Menger Prize Committee of the American Mathematical Society. This three-member committee is charged to select the winners in mathematics at the International Science and Engineering Fair sponsored by Intel. Several past winners of this competition for scientifically talented, secondary-school youth have eventually won Nobel Prizes and other prestigious honors.

Professor Richard S. Ellis and Professor Bruce Turkington were both invited lecturers at Ecole díEte de Physique Theorique in Les Houches, France. The aim of this month-long summer school was to present recent developments in the theoretical and experimental study of long-range, interacting systems. Twelve lecturers, approximately sixty graduate and postdoctoral students, and a number of other visitors participated. Richard lectured on the theory of large deviations and applications to statistical mechanics during the period August 5ñ8, 2008, and Bruce lectured on the statistical mechanics of two-dimensional turbulence and its geophysical applications during the period August 18ñ22, 2008.

Professor Paul Gunnells spoke at the workshop on *Multiple Dirichlet Series and Applications to Automorphic Forms,* which took place August 4ñ8, 2008 at the International Centre for Mathematical Sciences in Edinburgh, Scotland.

Professor Markos Katsoulakis received a CDI-Type II grant from the National Science Foundation for $1,600,000. The participating institutions are UMass Amherst, University of Delaware, and University of Tennessee. The title of the grant is *Collaborative Research CDI-Type II: Hierarchical Stochastic Algorithms for Materials Engineering.* That the competition for these grants was extremely keen can be seen from the fact that throughout all the science and engineering divisions of NSF only seven such grants were funded. A new NSF initiative, CDI is an acronym for Cyber-Enabled Discovery and Innovation.

Taking advantage of his stay at the University of Heidelberg as a Humboldt Fellow, Professor Panos Kevrekidis had a very busy summer. During the period July 21ñ24, 2008, he attended the conference on Nonlinear Waves in Rome, then went to Porto for the Nonlinear Science and Complexity meeting held there during the period July 27ñ30, and finally traveled to Athens for the Nonlinear Science and Complexity Summer School and Workshop held there during the period July 30 ñ August 2. In these meetings he delivered three different lectures on the following topics: discrete nonlinear Schroedinger equations and their solitary waves in Rome, double well potentials in optics and atomic physics in Porto, and examples of discreteness from granular media, layered optical media, and Bose-Einstein condensates in Athens.

During June and July, 2008 Professor Rob Kusner led a workshop at the Aspen Center for Physics on the *Geometry of Condensed Matter.* Earlier in June, he traveled to the University of Utah and to MSRI in Berkeley to work with collaborators. Later in July he delivered a plenary lecture at the IMA workshop on *Geometrical Singularities and Singular Geometries* and made several shorter presentations there as well. On his return trip, he visited the Liquid Crystal Institute at Kent State University, where he led a morning-long discussion on the *Geometry and Topology of Blue Phases.*

During the summer of 2008 Professor William Meeks gave talks at a geometry conference in Rome, in the geometry seminar at the University of Granada in Granada, Spain, at the conference on group actions at UMass Amherst, and in the geometry seminar at IMPA in Rio de Janeiro, Brazil. In November he will give colloquium talks at UMass Amherst and at Brandeis University.

Professor Franz Pedit gave the following four invited talks: *Global Aspects of Integrable Surface Geometry* at the conference on *Recent Advances in Geometry and Topology of Surfaces,* La Sapienza, Rome, Italy, May 28ñ30, 2008; *Global Aspects of Integrable Surface Geometry* at the conference on *Conformal Geometry: Invariant Theory and the Variational Method,* Station Biologique de Roscoff (CNRS), Roscoff , France, June 30 ñ July 4, 2008; *Why are Soap Bubbles Round?* for the Children University Program at Tuebingen University, June 17, 2008; and *Geometry and Space* for the Summer University Program at Tuebingen University, July 8, 2008. He also attended a meeting at the Mathematics Research Institute in Oberwolfach, Germany on Geometry, July 28 ñ August 1, 2008.

Professor Jenia Tevelev participated in the conference on *Geometric Invariant Theory,* which was held in Goettingen, Germany during the period June 2ñ6, 2008, and in the workshop on *Classical Algebraic Geometry,* which was held at the Mathematics Research Institute in Oberwalfach, Germany during the period June 9-13, 2008. The title of his talks at both the conference and the workshop was *Chow, Moduli-Theoretic, and Tropical Quotients of Grassmannians.* His paper entitled *Elimination Theory for Tropical Varieties,* written jointly with Bernd Sturmfels, was published in Mathematical Research Letters, volume 15, number 3 (2008).

During the period June 16ñ27, 2008 Professor Emeritus Floyd Williams presented a Graduate Workshop at the Mathematical Sciences Research Institute (MSRI) at the University of California, Berkeley. The workshop, entitled *A Window into Zeta and Modular Physics,* was attended by 33 gifted graduate students. It featured two daily lectures and a speakerís seminar in which four invited speakers gave advanced lectures on their current research. The workshop also featured special lectures by graduate students including Floydís two graduate students, Shabnam Beheshti and Jennie DíAmbroise. Shabnamís lecture was entitled * How a Soliton Illuminates a Black Hole,* and Jennieís lecture was entitled *On Relating d-Dimensional Cosmology to Bose-Einstein Condensates.* Floydís lecture at the speakerís seminar was entitled *Quantum Corrections to Black Hole Entropy Via a Deformation of the Patterson-Selberg Zeta Function.* Given the apparent success of the workshop, MSRI invited Floyd to edit a book entitled A Window into Zeta and Modular Physics. To be published by MSRI, the book will feature the daily lectures, the lectures given at the speakerís seminar, and the four special lectures by graduate students.

### June 2008

On May 24, 2008 Professor Erin Conlon gave an invited talk at the International Indian Statistical Association Conference held in Storrs, Connecticut during the period May 22ñ25, 2008. The talk was entitled *Bayesian Meta-Analysis Models for Microarray Studies.*

Professor Panos Kevrekidis had a busy spring during his sabbatical visit to the University of Heidelberg. In the first week of April, Panos co-organized and gave a talk at the Conference on Nonlinear Phenomena in Quantum Degenerate Gases that took place in Toledo, Spain. Panos also gave a pair of invited lectures in the workshop on Mathematical Topics in Electromagnetic Fields and Wave Propagation, organized at the University of Karlsruhe by Prof. G. Schneider and held on April 7ñ8, 2008. Finally, during the period May 6ñ13 Panos spent a dense week in the UK, where he gave four invited lectures at Imperial College, University of Oxford, University of Reading, and University of Nottingham. His paper, *Three Is a Crowd: Solitary Waves in Photorefractive Media with Three Potential Wells,* has been named one of three winners of the 2008 SIAM Outstanding Paper Prize. Co-authored with Todd Kapitula and Zhigang Chen, the paper appeared in the SIAM Journal on Applied Dynamical Systems in 2006.

Professor Michael Lavine delivered a talk entitled *Subjective Likelihood For An Assessment of Climate Change in the Ocean* at the International Conference on Interdisciplinary Mathematical & Statistical Techniques held in Memphis TN on May 16, 2008.

Professor Arunas Rudvalis has been named a General Education Fellow. This year-long program based in the Center for Teaching is intended to focus on General Education courses. As part of his fellowship, Arunas will be working on the Gen Ed course, Math 100. More information about the General Education Fellows program is available at http://www.umass.edu/loop/talkingpoints/articles/74960.php.

On May 15, 2008 Professor Emeritus Floyd Williams was presented a Certificate of Appreciation by Dr. John R. Mullin, Dean of the Graduate School. The certificate states the following: *In recognition of your outstanding record of teaching, advising, and mentoring of students at the University of Massachusetts Amherst.* The certificate was awarded in recognition of the facts that his two students, Jennie DíAmbroise and Shabnam Beheshti, were named winners of the Distinguished Teaching Award in 2007 and 2008, respectively, and that Floyd was nominated for that award in 2004. He was also invited to be one of ten banquet speakers to pay tribute to Professor Bertram Kostant of MIT at a conference given in honor of his 80th birthday. Entitled *Lie Theory and Geometry: The Mathematical Legacy of Bertram Kostant,* the conference was held at the University of British Columbia in Vancouver, Canada during the period May 19ñ24, 2008. The conference was sponsored by the Pacific Institute for the Mathematical Sciences and was co-sponsored by the Clay Mathematical Institute and the Massachusetts Institute of Technology. Twenty three international speakers gave talks.

On May 1, 2008 Professor Robin Young spoke at a KAM Theory Seminar at Boston University. In his talk, entitled *Shock-Free Periodic Solutions for the Euler Equations,* Robin spoke about progress on this important topic with his long-time collaborator, Blake Temple. He also attended a conference on Free Boundary Problems in Stockholm, Sweden during the period June 9ñ13, where he spoke on the same topic. Young has been invited to participate in the IMA summer program on Nonlinear Conservation Laws and Applications, which will take place during the period July 13ñ31, 2009.

### May 2008

On April 2, 2008 Professor Tom Braden gave a talk in the *Topology et. al.* seminar at Wesleyan University entitled *Toric and Hypertoric Varieties: Topology and Combinatorics.*

On April 5, 2008 Professor Eduardo Cattani gave a talk on *Rational Hypergeometric Functions in Two Variables* at the Special Session on D-Modules of the AMS Sectional Meeting in Bloomington, Indiana. He also attended the Workshop on Hodge Theory at the Banff International Research Station (BIRS) in Banff, Canada during the period April 6ñ11. A co-organizer of this workshop was Greg Pearlstein, who received his Ph.D. in our department in 1999 under the direction of Professor Aroldo Kaplan.

Professor Paul Gunnells attended the workshop Computing Arithmetic Spectra, held March 10ñ14, 2008 at the American Institute of Mathematics in Palo Alto, California.

During March and early April 2008, Professor Rob Kusner visited TU-Berlin and TU-Darmstadt in Germany, ETH in Zurich, Switzerland, and University of Milan in Italy. He pitched a season-opening double-header (and now has a 2.718281828... ERA) in the Augsburg-Darmstadt-Frankfurt-Heidelberg-Mannheim Geometric Analysis Oberseminar on April 11 on the topic of *Holomorphic Differentials and Surface Theory.* The first game was against an old combinatorial geometric problem of triangulating tori; using sextic differentials and Abelís Theorem, one can give a quick proof that there are no such triangulations with exactly one 5-fold and one 7-fold vertex. The second opponent was the classification of complex projective structures (which, via the Schwarzian, amount to the space of quadratic differentials with polynomial growth) on C and applications of this to the moduli space of constant mean curvature surfaces; in fact, a consequence of this approach is a slick *holomorphic* proof of Stasheffís theorem about the associahedron being a cell. Earlier that week in Milan, Rob pitched a special morning game against *Knotted Ropes and Bands,* and he faced the same rival again in the joint Bryn Mawr-Haverford Colloquium on April 28. Ball four!

Professor Michael Lavine gave a talk on April 2, 2008 at the University of Connecticut and a talk on April 10 at Boston University. Both talks were entitled *The Multiset Sampler, a New MCMC Algorithm.*

Visiting Assistant Professor Ralf Schiffler gave a talk at the International Conference on Representation Theory of Algebras and Related Topics, which took place at Woods Hole during the period April 25ñ27, 2008. The title of his talk was *Cluster-Tilted Algebras and Slices.*

Professor John Staudenmayer has been invited to become an associate editor of Biometrics, a applied statistics journal that is the premier publication of the International Biometrics Society.

During April 2008 Professor Jenia Tevelev gave a talk entitled *Hypergraph Curves, Divisors, and Morphisms* at the Commutative Algebra and Algebraic Geometry Seminar at the University of California Berkeley and a talk entitled *Tropical Compactifications* at the Toric Varieties Seminar at the University of California Berkeley and at the Geometry-Algebra-Singularities-Combinatorics Seminar at Northeastern University.

On April 26ñ27, 2008 Emeritus Professor Floyd Williams was one of six speakers in the Workshop on Lie Groups, Lie Algebras, and their Representations, held at the University of California at Santa Cruz. His one-hour talk was entitled *Zeta Integrals on Higher Rank Symmetric Spaces.* Among the other speakers was Zongzhu Lin, who received his Ph.D. in our department in 1989 under the direction of Professor Jim Humphreys. Now a professor at Kansas State University, Zongzhu Lin gave a talk entitled *Frobenius Twisted Conjugacy Classes In Full Matrix Rings.*