NYU Courant Mourns the Loss of Professor Jerry Percus

Our colleague Jerry Percus passed away on March 7 at the age of 94. Jerry came to the Courant Institute in 1958, after obtaining his doctorate at Columbia and working for several years at the Stevens Institute of Technology. Jerry was internationally recognized for his pioneering work in statistical mechanics and combinatorics, and made seminal contributions to our understanding of fluids and biomathematics.

In addition to the famous Percus-Yevick Equation for the radial distribution function of fluids, he alone or jointly with students and coworkers, made important advances in all aspects of statistical mechanics. He was the first (or among the very first) to study "consistency" of approximate one and two particle classical distributions and quantum density matrices. This led to the Percus-Yamada condition in the former. He derived and solved equations for the velocity correlation function of fluids. He was the acknowledged master of the statistical mechanics of non-uniform fluids. His analysis of non-isotropic fluids in terms of appropriately designed isotropic ones contributed much to this subject.

In recent decades Jerry's interests turned to pioneering studies in biomathematics, in particular genome analysis and developmental biology.  Many of his papers were in collaboration with his late wife, Ora. Jerry's unique and highly creative perspective on a wide range of problems in physics, mathematics, and biology will be greatly missed.

NYU Courant Mourns the Loss of Professor Andrew J. Majda

Andrew Joseph Majda passed away on March 12, 2021 at the age of 72.

Renowned for both his theoretical contributions to partial differential equations and his applied work in diverse areas such as asymptotic methods, numerical methods, scattering theory, shock waves, combustion, incompressible flow, vortex motion, turbulent diffusion, and atmosphere ocean science, Andy Majda made a number of seminal contributions in mathematics and physics. One of the most notable is the Beal-Kato-Majda theorem, which limits the possibility for singularities in inviscid, incompressible fluid flow. Andy’s primary research interests were in modern applied mathematics in the broadest possible sense merging asymptotic methods, numerical methods, physical reasoning, and rigorous mathematical analysis.

Andy was born on January 30, 1949 in East Chicago, Indiana. He earned his Bachelor of Science degree in Mathematics from Purdue University (1970) and his Ph.D. in Mathematics from Stanford (1973). His doctoral dissertation was entitled “Coercive Inequalities for Nonelliptic Symmetric Systems.” Andy first joined the NYU Courant Mathematics Department as a Courant Instructor in 1973 and was here for just two years before moving on to faculty appointments at UCLA, UC Berkeley, and Princeton. NYU was a special place for Andy, and he returned in 1994 as the Samuel F. B. Morse Professor of Arts and Sciences in the Mathematics Department at Courant and remained here since then. He retired on January 1, 2021 and became Professor Emeritus of Mathematics.

As a pioneering theoretical and applied mathematician, Andy consistently received scientific recognition throughout his career. One of his earliest honors was as plenary speaker at the first ever International Council of Industrial and Applied Mathematics (ICIAM) in Paris in 1987. Most recently, in 2016, Andy received the Leroy P. Steele Prize for seminal contribution to research, which is awarded by the American Mathematical Society (AMS). He received the Lagrange Prize of ICIAM, the Norbert Wiener Prize of the AMS and the Society of Industrial and Applied Mathematics (SIAM), the National Academy of Sciences Prize in Applied Mathematics and Numerical Analysis, the John von Neumann Prize of SIAM, and the Gibbs Prize of the AMS. Andy was elected as a member of the National Academy of Sciences, a fellow of the American Academy of Arts and Sciences, and a fellow of both the AMS and SIAM. Twice he was awarded the Medal of the College de France, and he was elected as a Fellow of the Japan Society for the Promotion of Science. He received Honorary Doctorates from Fudan University, China Northwest University, and Purdue University, as well as The New York City Mayor's Award for Excellence in Mathematical, Physical, and Engineering Sciences.

In addition to his outstanding research, Andy was a devoted PhD advisor to thirty doctoral students, a mentor to over thirty postdoctoral researchers, and he inspired many collaborators and others in the mathematical sciences community. His published books include Compressible Fluid Flow and Systems of Conservation Laws in Several Space Variables (Springer-Verlag), Vorticity and Incompressible Flow with A. Bertozzi (Cambridge University Press), Lecture Notes for the Courant Lecture Note Series of the AMS. Other published works include the Introduction to PDE’s and Waves for the Atmosphere and Ocean, the CRM monograph series on Information Theory and Stochastics for Multiscale Nonlinear Systems, with M. Grote and R. Abramov, all published by the AMS, and Nonlinear Dynamics and Statistical Theories for Basic Geophysical Flows with Xiaoming Wang published by Cambridge University Press. His newest book with John Harlim, is entitled Filtering Complex Turbulent Systems and was published Cambridge University Press.

Andy made major contributions to NYU, locally here at the NYU New York campus and overseas. In his years at the Courant Institute, Andy created the Center for Atmosphere Ocean Science (CAOS) with eight multi-disciplinary faculty to promote cross-disciplinary research with modern applied mathematics in climate modeling and prediction. Later, he founded NYU Abu Dhabi’s Center for Prototype Climate Modeling and served as its head and Principal Investigator. More recently, Andy’s research interests included multi-scale multi-cloud modeling for the tropics, stochastic and statistical modeling for climate, and novel mathematical strategies for prediction and data assimilation in complex multi-scale systems.

Andy is survived by his wife of 46 years, Gerta Keller, who is a Professor of Paleontology and Geology in the Geosciences Department of Princeton University. Full of energy and ideas, Andy was greatly influential at the Courant Institute and in the math community and will be dearly missed by all of his colleagues and friends.

Sylvia Serfaty Elected to the European Academy of Sciences

Congratulations, Sylvia! 

Yann LeCun, receives the ACM A.M. Turing Award!

See the NYU press release for more information. Congratulations, Yann!

Gerard Ben Arous and Lai-Sang Young elected to the National Academy of Sciences

For further information see the official announcement.

Advanced Micro Devices (AMD) Donation

Advanced Micro Devices (AMD) has made a donation to Courant of a computer system and access to cloud based computing, with up to 2 petaflops of computing power, for use in COVID-related research.

For more detail, see this letter from Courant Director, Russel Caflisch.

July 23, 2020

Dear Colleagues,

It’s my great pleasure to announce a truly impressive gift-in-kind to the Courant Institute that will have a profound impact on COVID-19-related research both at Courant and throughout NYU. Advanced Micro Devices (AMD), one of the country’s leading manufacturers of computer processors, is donating a high-performance computer system and remote access to a second, cloudbased system, with both systems consisting of AMD CPUs and GPUs. The first system will be located at NYU’s new High Performance Computing Center and the cloud-based system will be located at Penguin Computing. Together, the computer systems will provide our researchers with up to two petaflops of computing power. We will be putting these resources to use in projects from a wide range of disciplines to address numerous aspects of the COVID-19 crisis and related applications. These include research aimed at developing drugs that can be used to treat both COVID-19 and future SARS virus mutations; retrieval of relevant research findings from the vast biomedical literature; analysis of medical imaging for screening of patients; and studying political attitudes and voting behavior in response to financial hardships stemming from the pandemic. COVID-19 has had a profound impact on higher education research, both in terms of its direction and the need for immediate results, so the timing of this donation is particularly fortuitous. We are tremendously grateful to AMD for their extraordinary gift.


Russel Caflisch

Jeff Cheeger to receive an honorary degree from the University of Chicago

Jeff is one of six distinguished scholars who will receive the honorary degree in 2021. Further information can be found here.

Sloan Fellowship

Daniele Panozzo has been awarded a Sloan Fellowship for his work in solving partial differential equations on complex geometrical domains. Congratulations!

NYU Courant Mourns the Loss of Professor Louis Nirenberg

Louis Nirenberg died in New York City on January 26, 2020 at the age of 94.

He was a leading mathematician, whose fundamental contributions in the field of partial differential equations were hugely influential. This area of mathematics provides the language we use to describe—and the techniques we use to analyze—diverse problems from many fields, including geometry, physics, and engineering. Louis' earliest work, in the 1950's, solved two longstanding problems from geometry by proving new estimates for fully-nonlinear elliptic equations. Over the course of his long and productive career his achievements included the solution of many other important problems, and—equally significant—the introduction of many new ideas and techniques.

Louis was born in 1925 in Hamilton, Ontario, but grew up in Montreal. He studied Mathematics and Physics at McGill University, graduating in 1945, then came to New York University as a Mathematics masters student. The postwar years were a remarkable time for mathematics at NYU—his fellow students included Eugene Isaacson, Peter Lax, Joseph Keller, Martin Kruskal, Cathleen Morawetz, Harold Grad, and Avron Douglis. Louis remained at NYU for his entire career: after completing his PhD in 1949 with guidance from James Stoker and Kurt Friedrichs, he held a two-year postdoctoral position then joined the faculty in 1951. His title was Professor of Mathematics from 1957 until 1999, when he retired and became Professor Emeritus. He was Director of the Courant Institute from 1970 to 1972.

Louis' impact was partly due to his exquisite taste in problems. One very successful mode was to recognize, through specific challenges, the need for new tools or estimates. His ability to identify such challenges—and to find the required tools or estimates—was a major driver of his impact. His early work on problems from geometry had this character; other examples include his papers in the 60's with Joseph Kohn on problems from complex differential geometry, and those in the 80's with Haim Brezis on nonlinear elliptic equations with critical exponents.

A different, equally successful mode was to identify tools that were clearly important, then systematically explore their power. His work on the regularity of solutions of linear elliptic equations and systems had this character; it was done in the 50's and 60's with Shmuel Agmon and Avron Douglis. Another example is his work on the symmetry of solutions of nonlinear partial differential equations using the “method of moving planes” and the “sliding method,” developed in the 80's and 90's with Basilis Gidas, Wei-Ming Ni, and Henry Berestycki.

Louis also loved challenges—particularly ones involving estimates or inequalities—and this was the motivation for many projects. One example is his work on solutions of the incompressible Navier-Stokes equations, which describe for example the flow of water. We still don't know whether its solutions are smooth or not, so it is natural to ask about the size of the set where they are not smooth. The estimates Louis proved in the 80's with Luis Caffarelli and Robert Kohn remain the state of the art.

A gifted teacher and mentor, Louis was advisor to 46 PhD students (starting with Walter Littman in 1956 and ending with Kanishka Perera in 1997), and he also had a formative influence on many postdocs and collaborators.

Lively and gregarious, Louis loved music, art, and film almost as much as he loved mathematics. He maintained close friendships with many colleagues around the world. He loved to travel, and to host visitors. He particularly enjoyed working with others; as a result, almost all his papers were coauthored.

Louis received many prestigious awards, including the Abel Prize (2015), the American Mathematical Society's Leroy P. Steele Prizes for Seminal Contribution to Research (2014) and Lifetime Achievement (1994), the International Mathematical Union's Chern Medal (2010), the National Medal of Science (1995), the Canadian Mathematical Society's Jeffery-Williams Prize (1987), the Crafoord Prize (1982), and the American Mathematical Society's Bôcher Prize (1959).

He became a member of the American Academy of Arts and Sciences in 1965, a member of the National Academy of Sciences in 1969, and a Fellow of the American Mathematical Society in 2013. He was also a member of numerous honorary societies in other countries, including Accademia dei Lincei (1978), Accademia Mediterranea della Scienza (1982), Académie des Sciences (1989), Istituto Lombardo Accademia Scienze e Lettere (1991), Ukrainian Academy of Sciences (1994), and Norwegian Academy of Sciences and Letters (2015). He received honorary degrees from McGill University (1986), University of Pisa (1990), Université de Paris IX Paris-Dauphine (1990), McMaster University (2000), University of British Columbia (2010); and he was named Honorary Professor by Nankai University (1987), Zhejiang University (1988), and Peking University (2016).

Louis is survived by his son Marc, his daughter Lisa and her partner, Joseph Ganci, his grandchildren Jimmy and Alma, his sister Deborah, and his partner Nanette.

Additional information about Louis, including video, is available at the Simons Foundation's "Science Lives" website, via this link: https://www.simonsfoundation.org/2014/04/21/louis-nirenberg/

An autobiography is included in a recent book The Abel Prize 2013-2017 (H. Holden and R. Piene eds, Springer-Verlag, 2019, pp 379-389).

Legion of Honor

Yann LeCun has been named a Knight of the Legion of Honor. Congratulations!