Institute for Mathematics and its Applications University of Minnesota 114 Lind Hall 207 Church Street SE Minneapolis, MN 55455 
20092010 Program
See http://www.ima.umn.edu/20092010/ for a full description of the 20092010 program on Complex Fluids and Complex Flows.
10:45am11:15am  Coffee break  Lind Hall 400  
3:30pm4:30pm  Tag Team Tutorials: Transport & Mixing in Incompressible Fluid Flows  Charles R. Doering (University of Michigan) JeanLuc Thiffeault (University of Wisconsin)  Lind Hall 305  
5:00pm6:30pm  Mathematics awareness month lecture  Mathematics that swings: the math behind golf  Douglas N. Arnold (University of Minnesota)  Campus Center, Macalester College 
10:45am11:15am  Coffee break  Lind Hall 400 
10:45am11:15am  Coffee break  Lind Hall 400 
10:45am11:15am  Coffee break  Lind Hall 400  
11:15am12:15pm  Postdoc seminar: Coupled boundary layers for the primitive equations of atmosphere  Dongjuan Niu (Capital Normal University)  Lind Hall 305  PS 
10:45am11:15am  Coffee break  Lind Hall 400 
10:45am11:15am  Coffee break  Lind Hall 400  
3:30pm4:30pm  Tag Team Tutorials: Transport & Mixing in Incompressible Fluid Flows  Charles R. Doering (University of Michigan) JeanLuc Thiffeault (University of Wisconsin)  Lind Hall 305 
10:45am11:15am  Coffee break  Lind Hall 400  
1:15pm1:45pm  Registration and coffee  Lind Hall 400  SW4.9.10  
1:25pm2:25pm  Applying numerical grid generation to the visualization of complex function data  Bonita V. Saunders (National Institute of Standards and Technology)  Vincent Hall 570  IPS 
1:45pm2:00pm  Welcome and introduction  Fadil Santosa (University of Minnesota)  Lind Hall 305  SW4.9.10 
2:00pm3:00pm  Using topology to understand chromosome organization across organisms  F. Javier Arsuaga (San Francisco State University)  Lind Hall 305  SW4.9.10 
3:00pm4:00pm  Biological applications that utilize DNA Topology  Lynn Zechiedrich (Baylor College of Medicine)  Lind Hall 305  SW4.9.10 
4:00pm4:10pm  Group Photo  SW4.9.10  
4:10pm6:10pm  Poster Session and Refreshments Poster submissions welcome from all participants Instructions  Lind Hall 400  SW4.9.10  
Solving a system of four tangle equations  Lauren M. Beaumont (University of Iowa) Dianne Smith (University of Iowa)  
Engineering multiple sitespecific modifications in supercoiled DNAs  Anusha Bharadwaj (University of Texas at Dallas)  
Three dimensional reconstructions of knotted particles  John Collins (San Francisco State University)  
Table of rational links and their invariants  Isabel K. Darcy (University of Iowa) Guanyu Wang (University of Iowa)  
Modeling local knots in proteins caused by random crossing changes  John R. Froehlig (University of Iowa)  
Direct entropy calculations for discrete wormlike chains  Stefan M. Giovan (University of Texas at Dallas)  
Braid indices in a class of closed braids  Kenneth E. Hinson (University of North Carolina  Charlotte)  
High school level introduction to knots  Jeffrey Hunt (University of Iowa)  
Symmetries of knots and links  Matt Mastin (University of Georgia)  
Energetics of DNA tangling in complex nucleoprotein assemblies  Mary Therese Padberg (University of Iowa) Gregory Witt (University of Iowa)  
Invariance of the sign of the average space writhe of free and confined knotted polygons  Juliet Portillo (San Francisco State University)  
Minimal step number of cubic lattice knots in thin slabs  Robert Glenn Scharein (San Francisco State University)  
Symmetrybreaking in cumulative measures of shapes of polymer models  Vy T. Tran (University of St. Thomas)  
Polygonal cable links  Rolland Trapp (California State University)  
Tangle tabulation  Danielle Washburn (University of Iowa)  
The local and global shape of regular embedded polygons: Theoretical and experimental  Laura K. Zirbel (University of California, Santa Barbara) 
8:00am8:45am  Registration and coffee  EE/CS 3176  W4.1216.10  
8:45am9:00am  Welcome to the IMA  Fadil Santosa (University of Minnesota)  EE/CS 3180  W4.1216.10 
9:00am9:45am  Transittime distributions: A tool to diagnose rates and pathways of tracer transport in advective/diffusive flow  Thomas W. N. Haine (Johns Hopkins University)  EE/CS 3180  W4.1216.10 
9:45am10:00am  Discussion  EE/CS 3180  W4.1216.10  
10:00am10:45am  The inverse problem of inferring transittime distributions from tracer observations in the ocean  François W. Primeau (University of California, Irvine)  EE/CS 3180  W4.1216.10 
10:45am11:00am  Discussion  EE/CS 3180  W4.1216.10  
11:00am11:45am  Exit time problem in an incompressible flow  Alexei Novikov (Pennsylvania State University)  EE/CS 3180  W4.1216.10 
11:45am12:00pm  Discussion  EE/CS 3180  W4.1216.10  
12:00pm2:00pm  Lunch  W4.1216.10  
2:00pm2:45pm  Dynamics of shallow water layer models: Stability, wave breaking and mixing  Paul Milewski (University of Wisconsin)  EE/CS 3180  W4.1216.10 
2:45pm3:00pm  Discussion  EE/CS 3180  W4.1216.10  
3:00pm3:45pm  Modelling streaming by surface acoustic waves  Jacques Vanneste (University of Edinburgh)  EE/CS 3180  W4.1216.10 
3:45pm4:00pm  Discussion  EE/CS 3180  W4.1216.10  
4:00pm4:15pm  Group Photo  W4.1216.10  
4:15pm6:00pm  Reception and Poster Session Poster submissions welcome from all participants Instructions  Lind Hall 400  W4.1216.10  
A numerical study of the effect of diffusion on a fast chemical reaction in a twodimensional turbulent flow  Farid Ait Chaalal (McGill University)  
The spectrallyhyperviscous NavierStokes equations  Joel D. Avrin (University of North Carolina  Charlotte)  
RayleighTaylor turbulence: a simple model for heat transfer in thermal convection  Guido Boffetta (Università di Torino)  
A fast explicit operator splitting method for passive scalar advection  Alina Chertock (North Carolina State University) Charles R. Doering (University of Michigan) Alexander Kurganov (Tulane University)  
Lowdimensional models from upper bound and energy stability theory  Gregory P. Chini (University of New Hampshire)  
Chaotic granular mixing in quasitwodimensional tumblers: streamline jumping, piecewise isometries and strange eigenmodes  Ivan Christov (Northwestern University)  
Alternate powers in Serrin's swirling vortex solutions 2  Doug Dokken (University of St. Thomas)  
A class of HamiltonJacobi PDE in space of measures and its associated compressible Euler equations  Jin Feng (University of Kansas)  
Active and hibernating turbulence in channel flow of Newtonian and viscoelastic fluids  Michael D. Graham (University of Wisconsin)  
Bridging the Boussinesq and primitive equations through spatiotemporal filtering  Traian Iliescu (Virginia Polytechnic Institute and State University)  
Homogenization and mixing measures for a replenishing passive scalar field  Shane Keating (New York University)  
Miscible and immiscible RayleighTaylor turbulence  Andrea Mazzino (Università di Genova)  
On the effect of initial velocity field and phase shifting of an initial binary perturbation for RayleighTaylor instability  Bertrand Rollin (Los Alamos National Laboratory)  
Numerical studies in shallow moist convection  Joerg Schumacher (Ilmenau University of Technology)  
Lagrangian dynamics in stochastic inertiagravity waves  Wenbo Tang (Arizona State University)  
Superconvergence for the 3D NavierStokes  Giordano Tierra Chica (University of Sevilla)  
Fast chemical reactions in chaotic flows: Reaction rate and mixdown time  YueKin Tsang (University of California, San Diego)  
Estimating generalised Lyapunov exponents for random flows  Jacques Vanneste (University of Edinburgh)  
Shear cell rupture of nematic droplets in viscous fluids  Xiaofeng Yang (University of South Carolina) 
8:30am9:00am  Coffee  EE/CS 3176  W4.1216.10  
9:00am9:45am  Progress & problems in the analysis of turbulent transport & mixing  Charles R. Doering (University of Michigan)  EE/CS 3180  W4.1216.10 
9:45am10:00am  Discussion  EE/CS 3180  W4.1216.10  
10:00am10:45am  Setting limits on turbulence  balancing rigor with practicality  Rich R. Kerswell (University of Bristol)  EE/CS 3180  W4.1216.10 
10:45am11:00am  Discussion  EE/CS 3180  W4.1216.10  
11:00am11:45am  Approximating the rate of heat transport  Xiaoming Wang (Florida State University)  EE/CS 3180  W4.1216.10 
11:45am12:00pm  Discussion  EE/CS 3180  W4.1216.10  
12:00pm2:30pm  Lunch  W4.1216.10  
2:30pm3:15pm  Radial basis functions for geofluid modeling  Natasha Flyer (National Center for Atmospheric Research)  EE/CS 3180  W4.1216.10 
3:15pm3:30pm  Discussion  EE/CS 3180  W4.1216.10  
3:30pm4:15pm  A Stokesian viscoelastic flow: Transition to mixing and oscillations  Becca Thomases (University of California, Davis)  EE/CS 3180  W4.1216.10 
4:15pm4:30pm  Discussion  EE/CS 3180  W4.1216.10 
8:30am9:00am  Coffee  EE/CS 3176  W4.1216.10  
9:00am9:45am  Mixing by eddies in the atmosphere and ocean  Emily F. Shuckburgh (British Antarctic Survey)  EE/CS 3180  W4.1216.10 
9:45am10:00am  Discussion  EE/CS 3180  W4.1216.10  
10:00am10:45am  The threedimensional structure of turbulent geostrophic stirring  K. Shafer Smith (New York University)  EE/CS 3180  W4.1216.10 
10:45am11:00am  Discussion  EE/CS 3180  W4.1216.10  
11:00am11:45am  Do fish stir the ocean?  JeanLuc Thiffeault (University of Wisconsin)  EE/CS 3180  W4.1216.10 
11:45am12:00pm  Discussion  EE/CS 3180  W4.1216.10 
8:30am9:30am  Coffee  EE/CS 3176  W4.1216.10  
9:30am10:15am  Spatial structures of chaotically advected reactive tracers: The role of a delay time  Alexandra Tzella (École Normale Supérieure)  EE/CS 3180  W4.1216.10 
10:15am10:30am  Discussion  EE/CS 3180  W4.1216.10  
10:30am11:15am  Broadcast spawning: A new class of reactionmixing problems  Jeffrey B. Weiss (University of Colorado)  EE/CS 3180  W4.1216.10 
11:15am11:30am  Discussion  EE/CS 3180  W4.1216.10  
11:30am12:15pm  Mixing and enhanced relaxation in fluid flows  Alexander Kiselev (University of Wisconsin)  EE/CS 3180  W4.1216.10 
12:15pm12:30pm  Discussion  EE/CS 3180  W4.1216.10  
12:30pm3:00pm  Lunch  W4.1216.10  
3:00pm3:45pm  Passive scalar advection in parallel shear ﬂows: WKBJ mode sorti on intermediate times and the evolution of skewness  Richard M. McLaughlin (University of North Carolina)  EE/CS 3180  W4.1216.10 
3:45pm4:00pm  Discussion  EE/CS 3180  W4.1216.10  
4:00pm4:45pm  Mixing: Visualization, norms, and control  Igor Mezic (University of California, Santa Barbara)  EE/CS 3180  W4.1216.10 
4:45pm5:00pm  Discussion  EE/CS 3180  W4.1216.10  
6:00pm8:00pm  Workshop dinner at Pagoda Restaurant  Pagoda Restaurant 1417 4th St. SE Minneapolis, MN 6123784710 
W4.1216.10 
8:30am9:00am  Coffee  EE/CS 3176  W4.1216.10  
9:00am9:45am  Bounds on mixing in stratified shear flows  Colm P. Caulfield (University of Cambridge)  EE/CS 3180  W4.1216.10 
9:45am10:00am  Discussion  EE/CS 3180  W4.1216.10  
10:00am10:45am  Jet dynamics in stratified media  Juan Mario Restrepo (University of Arizona)  EE/CS 3180  W4.1216.10 
10:45am11:00am  Discussion  EE/CS 3180  W4.1216.10  
11:00am11:45am  Is turbulence stable?  William Roy Young (Scripps Research Institute)  EE/CS 3180  W4.1216.10 
11:45am12:00pm  Discussion  EE/CS 3180  W4.1216.10  
12:00pm12:15pm  Closing remarks  EE/CS 3180  W4.1216.10 
10:45am11:15am  Coffee break  Lind Hall 400 
11:15am12:15pm  Special seminar: Wave and curves  Gregory R. Baker (Ohio State University)  Lind Hall 305  PS 
10:45am11:15am  Coffee break  Lind Hall 400 
10:45am11:15am  Coffee break  Lind Hall 400  
7:00pm8:00pm  Can chocolate save your life?  Nancy Reid (University of Toronto)  Willey Hall 175  PUB4.22.10 
10:45am11:15am  Coffee break  Lind Hall 400 
10:45am11:15am  Coffee break  Lind Hall 400 
10:45am11:15am  Coffee break  Lind Hall 400  
11:15am12:15pm  TBA  ChiunChang Lee (National Taiwan University)  Lind Hall 305  PS 
10:45am11:15am  Coffee break  Lind Hall 400 
10:45am11:15am  Coffee break  Lind Hall 400 
10:45am11:15am  Coffee break  Lind Hall 400  
1:25pm2:25pm  Optimal chemical spectroscopy  Anthony José Kearsley (National Institute of Standards and Technology)  Vincent Hall 570  IPS 
Event Legend: 

IPS  Industrial Problems Seminar 
PS  IMA Postdoc Seminar 
PUB4.22.10  Nancy Reid: Can Chocolate Save Your Life? 
SW4.9.10  Physical Knotting and Linking and its Applications 
T4.11.10  Transport and Mixing in Complex and Turbulent Flows 
W4.1216.10  Transport and Mixing in Complex and Turbulent Flows 
Farid Ait Chaalal (McGill University)  A numerical study of the effect of diffusion on a fast chemical reaction in a twodimensional turbulent flow 
Abstract: Stratospheric ClimateChemistry Models neglect the effects of subgrid flow structures on chemistry. Several previous studies have pointed out that such unresolved small scales could significantly affect the chemistry . However this problem has not been thoroughly studied from a theoretical point of view. To fulfill this gap, we investigate the interactions between advection, diffusion and chemistry for a simple bimolecular reaction between two initially unmixed reactants, within the framework of twodimensional isotropic and homogeneous turbulence. This is a highly simplified representation of quasiisentropic mixing in the stratosphere. Our goal here is to describe and understand how the production rate is affected by the size of the smallest scales of the tracer field, as determined by the tracer diffusion. We focus on the case of an infinitely fast chemical reaction. Our results show a strong dependence of the total production on the diffusion coefficient. This production scales like the diffusion to the power of p(t), where p(t) is a positive decreasing function of time. This dependence is particularly important during an initial transient regime and is affected by the separation between the reactants at the initial time. This first regime is characterized by an exponential lengthening of the boundary between the reactants. The evolution of the tracer gradients along this interface explains the dependence of the chemistry on the diffusion. For larger times, our simulations suggest the appearance of an asymptotic strange eigenmode that controls the decay of the reactants.  
Douglas N. Arnold (University of Minnesota)  Mathematics awareness month lecture  Mathematics that swings: the math behind golf 
Abstract: Mathematics is everywhere and the golf course is no exception. Many aspects of the game of golf can be illuminated or improved through mathematical modeling and analysis. We will discuss a few examples, employing mathematics ranging from simple high school algebra to computational techniques at the frontiers of contemporary research.  
F. Javier Arsuaga (San Francisco State University)  Using topology to understand chromosome organization across organisms 
Abstract: Topological methods have been mostly used to study the action of enzymes and properties of naked DNA molecules. However topology can also be used to study chromosome organization. In this talk I will present three problems in which topology can be used to study complex organization of DNA. First I will present the problem of DNA knotting in bacteriophages. Understanding the organization of the genome in bacteriophages is important because bacteriophages are good models for DNA organization in some animal viruses (such as herpex viruses) and in DNA lipocomplexes used in gene therapy. Our approach is based on work by Liu, Calendar, Wang and colleagues that showed that DNA extracted from bacteriophage P4 is knotted. We have investigated these knots and shown that they are informative of the organization of the genome inside the capsid. I will present models that have been derived from these knots as well as the mathematical problems that this biological problem has generated. Second I will discuss the problem of chromosome intermingling of chromosome territories in the eukaryotic cell. During the G0/G1 phase of the cell cycle the eukaryotic genome is organized into chromosome territories. The positions of these territories as well as the structure along their surface are believed to play a major role in the formation of recurrent aberrations found in some genetic diseases and in some cancers. I will present some of our results on the topological implications of the Interchromosomal Network Model proposed by Branco and Pombo. In particular I will introduce our estimation of the linking probability of two neighboring chromosome territories assuming that chromatin fibers follow random trajectories. Third I will present some new and unpublished results on the linking of mitochondrial DNA in trypanosomes. Trypanosomatid parasites, trypanosoma and lishmania, are the cause of disease and death in many third world countries. One of the most unusual features of these organisms is the 3 dimensional organization of their mitochondrial DNA into maxi and minicircles. Minicircles are confined into a small volume and are interlocked forming a huge network. Some initial models for the organization of this network were proposed by Cozzarelli and Englund. Here we discuss some of the possible pathways for the formation and maintenance of this network as well as the mathematical results that derive from this problem. This work is in collaboration with: Y. Diao (UNC Charlotte), R. Scharein (SFSU), R. Kaplan (SFSU) and M. Vazquez (SFSU).  
Joel D. Avrin (University of North Carolina  Charlotte)  The spectrallyhyperviscous NavierStokes equations 
Abstract: We regularize the 3D NavierStokes equations with hyperviscosity of degree alpha, but applied only to the high wavenumbers past a cutoff m; such a technique is also designed to approximate the subgridscale modeling effects of spectral eddy viscosity. Attractor estimates stay within the LandauLifschitz degreesoffreedom estimates even for very large m. An inertial manifold exists for m large enough whenever alpha is at or above 3/2. Galerkinconvergence and inviscidlimit results are optimized for the high wavenumbers; the latter case is defined to mean that nu goes to zero while the spectral hyperviscous term stays fixed. Computational studies over many runs produce parameter choices that facilitate closetoparallel agreement (over a goodsized portion of the inertial range) with the Kolmogorov energyspectrum power law for high (up to 10^{7}) Reynolds numbers.  
Gregory R. Baker (Ohio State University)  Special seminar: Wave and curves 
Abstract: Water waves are perhaps the most notable feature of the planet, and they have occupied the attention of scientists since the birth of civilization. Yet they remain incompletely understood. Despite recent theoretical advances, the generic mathematical behavior of water waves eludes description. I will present a different view of water waves traveling in twodimensions, a view based on the relationship between the curvature and the arclength. The curvature has simple poles in the complex arclength plane that travel about while retaining their form. They can approach closely to the real axis during wave breaking and are associated with the tip of the plunging breaker. A different view of wave breaking is the presence of a squareroot singularity in the surface height as a function of the horizontal coordinate that reaches the real axis in finite time when the slope becomes vertical. Even in the absence of wave breaking, these singularities are present and strongly affect the wave spectra.  
Lauren M. Beaumont (University of Iowa), Dianne Smith (University of Iowa)  Solving a system of four tangle equations 
Abstract: A tangle consists of strings properly embedded within a 3dimensional ball. Solutions of tangle equations have proven quite useful when applied to recombinases. Recombinases are enzymes that cut DNA strands and interchange the ends, changing the topology of the DNA. The recombinase action will be mathematically modeled by replacing the zero tangle with the tangle t/w, resulting in a new DNA product. If we model experiments involving two topologically different substrates and/or two topologically different products, we have a corresponding system of four tangle equations. Given a1, a2, b1, b2, z1, z2, v1, and v2, we are solving the following system of four tangle equations for t/w:
N(j1/p1 + 0/1) = N(a1/b1) N(j1/p1 + t/w) = N(z1/v1) N(j2/p2 + 0/1) = N(a2/b2) N(j2/p2 + t/w) = N(z2/v2). 

Anusha Bharadwaj (University of Texas at Dallas)  Engineering multiple sitespecific modifications in supercoiled DNAs 
Abstract: Joint work with Matthew R. Kesinger^{*}, Massa J. Shoura^{*},
Alexandre Vetcher^{*}, and Stephen D. Levene^{*†}.
Biological processes such as DNA recombination, replication,
and gene expression involve specific interactions between one
or more DNAbinding proteins and multiple proteinbinding sites
along a single DNA molecule. Such interactions lead to the
formation of a topologically closed DNA loop between
proteinrecognition sites, whose energetics depends on the
structure and the flexibility of the intervening DNA, the
degree of supercoiling, and the binding of additional proteins
such as HU and Fis in bacterial systems or histones and HMG
proteins in the case of eukaryotic cells. We present here a
novel technique for incorporating multiple modifications such
as covalently attached fluorescent probes to multiple defined
sites within covalently closed DNA molecules. Applications of
this technology include the use of two and threecolor FRET to
investigate effects of DNA supercoiling on lacrepressor DNA
interactions both in vitro and in vivo.
Departments of Molecular and Cell Biology^{*} and Physics^{†} University of Texas at Dallas Richardson, TX 75080 

Guido Boffetta (Università di Torino)  RayleighTaylor turbulence: a simple model for heat transfer in thermal convection 
Abstract: I will discuss turbulent mixing within the framework of RayleighTaylor geometry. Large scale properties of mixing are described by a simple nonlinear diffusion model, derived within the general framework of Prandtl mixing theory, which fits very well the evolution of turbulent profiles obtained from numerical simulations. The effect of polymer additives is then discussed and on the basis of numerical simulations of complete viscoelastic models we obtain clear evidence that the heat transport is enhanced up to 50% with respect to the Newtonian case. This phenomenon is accompanied by a speed up of the mixing layer growth.  
Colm P. Caulfield (University of Cambridge)  Bounds on mixing in stratified shear flows 
Abstract: Keywords: Turbulent mixing, Rigorous bounds, stratified shear flows Abstract: Parameterizing the mixing of a stratified fluid subject to shear is a fundamental challenge for models of environmental and industrial flows. In particular, it is of great value to parameterize the efficiency of turbulent mixing, in the sense of the proportion of the kinetic energy converted into potential energy (through irreversible mixing of fluid of different density) compared to the total amount converted to both potential energy and internal energy (through viscous dissipation). Various competing models have been presented to relate the mixing efficiency to bulk properties of the flow, especially through different Richardson numbers, which quantify the relative importance of buoyancy and shear within the flow. One promising approach is to construct rigorous bounds on the longtime average of the buoyancy flux (i.e. the mixing rate) within simple model stratified shear flows, imposing physically reasonable constraints on the model flow fields. In this talk, we apply this technique to stably stratified Couette flow. By identifying the stratification which leads to maximal buoyancy flux, we make a prediction of what bulk stratification (as a function of the shear) is optimal for turbulent mixing. A previous attempt to do this failed due to an unexpected degeneracy in the variational problem. Here, we overcome this issue by parameterizing the variational problem implicitly with the overall mixing efficiency which is then optimized across to return a rigorous upper bound on the buoyancy flux. We discuss the implications of our results for various classical stratified shear turbulence models. Joint work with W. Tang (Arizona State University) & R. R. Kerswell (University of Bristol).  
Alina Chertock (North Carolina State University), Charles R. Doering (University of Michigan), Alexander Kurganov (Tulane University)  A fast explicit operator splitting method for passive scalar advection 
Abstract: Joint work with Alina Chertock, Charles R. Doering and Eugene Kashdan. The dispersal and mixing of scalar quantities such as concentrations or thermal energy are often modeled by advectiondiffusion equations. Such problems arise in a wide variety of engineering, ecological and geophysical applications. In these situations a quantity such as chemical or pollutant concentration or temperature variation diffuses while being transported by the governing flow. In the passive scalar case, this flow prescribed and unaffected by the scalar. Both steady laminar and complex (chaotic, turbulent or random) timedependent flows are of interest and such systems naturally lead to questions about the effectiveness of the stirring to disperse and mix the scalar. The development of reliable numerical methods for advectiondiffusion equations is crucial for understanding their properties, both physical and mathematical. In this work, we extend a fast explicit operator splitting method, recently proposed in [A. Chertock, A. Kurganov, and G. Petrova, International Journal for Numerical Methods in Fluids, 59 (2009), pp. 309332] for solving deterministic convectiondiffusion equations, to the problems with random velocity fields and singular source terms. A superb performance of the method is demonstrated on several twodimensional examples.  
Gregory P. Chini (University of New Hampshire)  Lowdimensional models from upper bound and energy stability theory 
Abstract: Joint work with N. Dianati, Z. Zhang, and C. Doering.
A novel model reduction strategy for forceddissipative infinitedimensional nonlinear dynamical systems is described. Unlike popular but empirical methods (e.g. based on the Proper Orthogonal Decomposition), this new approach does not require extensive data sets from experiments or full PDE simulations. Instead, truly predictive reducedorder models are constructed via Galerkin projection of the governing PDEs onto apriori basis functions. This basis set is obtained by solving a constrained eigenvalue problem drawn from energy stability and upper bound theory. Within the context of porous medium convection, we show that these eigenfunctions contain information about boundary layers and other complex dynamic features and, thus, are well suited for the loworder description of highly nonlinear phenomena. Crucially, our analysis reveals a gap in the eigenvalue spectrum that persists even for strongly supercritical forcing conditions, thereby enabling the identification of a rational truncation scheme. We demonstrate the efficacy of our approach via comparisons with FourierGalerkin approximations of various orders. 

Ivan Christov (Northwestern University)  Chaotic granular mixing in quasitwodimensional tumblers: streamline jumping, piecewise isometries and strange eigenmodes 
Abstract: The singular limit of a vanishing flowing layer in a tumbled granular flow is studied numerically, analytically and experimentally. We formulate the noshearlayer dynamical system as a piecewise isometry (PWI) and show that the mechanism of streamline jumping leads to mixing. In the special case of a halffull tumbler, chaotic behavior is shown to disappear completely in the singular limit. Experimental results are compared to the zerothorder PWI model and a realistic continuum model, showing that the noshearlayer dynamics form the skeleton of the granular flow. Even though, in this limit, stretching in the sense of shear strain is replaced by spreading due to streamline jumping, finitetime Lyapunov exponents and Lagrangian coherent structures still reveal the manifold structure of the flow. Finally, using the simplified mapping method, the asymptotic mixing pattern in a tumbled granular flows is decomposed into eigenmodes, showing a significant number of strange eigenmodes. These appear align with the unstable manifolds, which have been shown to outline the shape of segregation patterns in bidisperse granular mixing experiments in polygonal tumblers. Coauthors: Julio M. Ottino (Northwestern Univeristy, http://mixing.chemeng.northwestern.edu) and Richard M. Lueptow (Northwestern University, http://www.mech.northwestern.edu/lueptow).  
John Collins (San Francisco State University)  Three dimensional reconstructions of knotted particles 
Abstract: Single Particle Reconstructions are commonly used to elucidate structures of different types of small particles with precision approaching that of xray techniques. Such reconstructions assume a homogeneity of data or a small heterogeneous collection of homogeneous subgroups. Current models of the packing of small capsid viruses like bacteriophages suggest a spooling type model with some nonuniformity resulting in small numbers of knots. Three dimensional reconstructions have been used to justify different models but such assumptions assuming uniform homogeneity of a data set disregard slight variations which could be present. We present a look at the single particle reconstruction process as a whole as well as a view of two different sets of data. We ask, "what happens if single particle reconstruction is used to reconstruct a single model from a data set in which each particle is very similar but no two are exactly alike?".  
Isabel K. Darcy (University of Iowa), Guanyu Wang (University of Iowa)  Table of rational links and their invariants 
Abstract: Joint work with Thomas LeHew and Joe Eichholz. We are creating a webpage which will allow users to create tables of links, knots and their invariants. Our plan is to provide a platform which visualizes the information about knots and links on a table that will satisfy most types of users. The best platform for this plan is a webpage. The webpage would be separated into three main components. First, the actually html document that the user will see and interact with to properly generate the specific table of knots/links that the user would like to see. Second, a series of scripts will be set up to take in the input provided to retrieve the information needed from the database and then output the information in an easy to read table for the user to see. Last, a component specific to our project is the desire to allow others to contribute to the table. Livingston and Cha’s KnotInfo is an outstanding webpage for creating knot tables. However, for our project, we put more emphasis on links and their relevant invariants. It will also handle composition of links, orientation, and mirror images.  
Charles R. Doering (University of Michigan)  Progress & problems in the analysis of turbulent transport & mixing 
Abstract: Keywords: turbulent energy dissipation, eddy viscosity, effective diffusion, mixing efficiency Abstract: Several open problems in the analysis of turbulent transport and mixing are described. Among these are the determination of physically relevant bounds on turbulent dissipation and eddy viscosities in a variety of flow configurations, the accurate estimation of active and passive scalar transport and effective diffusivites, and questions of effective mixing.  
Doug Dokken (University of St. Thomas)  Alternate powers in Serrin's swirling vortex solutions 2 
Abstract: Joint work with Kurt Scholz, and Misha Shvartsman, University of St. Thomas, St. Paul, MN, USA. Motivated by results of Cai(2005, Monthly Weather Review), we consider alternate power dependencies in Serrin's Swirling Vortex model. We also give a heuristic argument to justify Cai's power law for tornados.  
Jin Feng (University of Kansas)  A class of HamiltonJacobi PDE in space of measures and its associated compressible Euler equations 
Abstract: We introduce a class of action integrals defined over probability measurevalued path space. We show that minimal action exists and satisfies a compressible Euler equation in weak sense. Moreover, we prove that both Cauchy and resolvent formulations of the associated HamiltonJacobi equation, in the space of probability measures, are well posed. There are two key arguments which involves relaxation and regularization in formulation of the problem. They are probabilistically motivated. This is a joint work with Truyen Nguyen.  
Natasha Flyer (National Center for Atmospheric Research)  Radial basis functions for geofluid modeling 
Abstract: Keywords: meshless methods, radial basis functions, geosciences Abstract: The most classical approach for solving PDEs numerically is finite difference methods (FD). Although they are easy to implement, their accuracy is often low. In contrast, pseudospectral methods (PS) can give spectral (exponential) convergence but suffer from severe geometric restrictions. On the other hand, radial basis function methods (RBF), based on expansions of translates of a single radially symmetric function, combine algorithmic simplicity with spectral accuracy while generalizing to arbitrary node layouts. Since they do not depend on any grid, RBFs allow for high geometric flexibility, permitting local node refinements in critical areas. Only within the last few years have they been applied to nontrivial PDE systems, illustrating their potential in the geosciences. Here, the application of the RBF method to three common geoscience benchmark cases of increasing complexity will be discussed. The first case is idealized cyclogenesis, which models the wrapup of vortices as they traverse the sphere. For this case, we will also show the simplicity of implementing local node refinement. The second case is unsteady nonlinear flows described by the shallow water equations. The third case is thermal convection in a 3D spherical shell, a situation of interest in modeling the earth's mantle. Current research topics focus on developing fast and efficient RBF algorithms that are parallelizable.  
John R. Froehlig (University of Iowa)  Modeling local knots in proteins caused by random crossing changes 
Abstract: Proteins are linear chains of amino acids. Proteins are composed of secondary structure units called alpha helices and beta sheets, which are energetically stable, and random coils, which are not. Many diseases are caused by protein folding disorders. Local knots in proteins are much rarer than is expected for a long polymer. As of 2006, only thirtynine proteins out of 9,553 proteins with determined structures contain local knots. Eighteen of those thirtynine proteins contain shallow knots which can deform to the unknot with the removal of five to ten residues from the N and Ctermini, which are the ends of the protein. The most complicated knot in proteins with known structures is the 5_2 knot found in ubiquitin hydrolase (pdb code 1xd3). The purpose of this project is to engineer knots into proteins with known structures that currently do not contain knots. The archive for all current structures of proteins and nucleic acids is the Protein Data Bank (PDB). For the purpose of this project, the central carbon atom will signify the amino acid. We will use a program called KnotPlot to graph the coordinates of each alpha carbon and join the two termini. From here, we will perform crossing changes in random coils on the chain and determine whether this creates a local knot that is not the unknot. Since most proteins are linear strands and not closed loops, it is not generally possible to talk about mathematical knots in proteins. We will start with choosing a method to close the gap between the N and Ctermini. As a positive control, we will start by using proteins with local knots to see if the algorithm works. We will then perform crossing changes caused by changing random coils. We will create a protocol to do these functions using KnotPlot, and then write a program to do this automatically so that we can discover all places that can be knotted.  
Stefan M. Giovan (University of Texas at Dallas)  Direct entropy calculations for discrete wormlike chains 
Abstract: Joint work with Stephen D. Levene^{*†}.
The thermodynamic properties of a semiflexible linear polymer,
DNA for example, are examined using discrete wormlike chains
(dWLCs) as a model. Monte Carlo ensembles of dWLCs were
generated to investigate the effect of excluded volume on the
configurational entropy of the chain, SC, which is calculated
based on the Schlitter approximation. We examined the
dependence of absolute and relative entropies on the cylinder
diameter and also practical aspects of this approach such as
fluctuations in computed SC values as a function of ensemble
size. Future applications include estimating the free energy
of DNA looping in complex nucleoprotein assemblies.
Departments of Molecular and Cell Biology^{*} and Physics^{†} University of Texas at Dallas Richardson, TX 75080 

Michael D. Graham (University of Wisconsin)  Active and hibernating turbulence in channel flow of Newtonian and viscoelastic fluids 
Abstract: Turbulent channel flow of dragreducing polymer solutions is simulated in minimal flow geometries. Even in the Newtonian limit, we find intervals of ``hibernating'' turbulence that display many features of the universal maximum drag reduction (MDR) asymptote observed in polymer solutions: weak streamwise vortices, nearly nonexistent streamwise variations and a mean velocity gradient that quantitatively matches experiments. As viscoelasticity increases, the frequency of these intervals also increases, while the intervals themselves are unchanged, leading to flows that increasingly resemble MDR.  
Thomas W. N. Haine (Johns Hopkins University)  Transittime distributions: A tool to diagnose rates and pathways of tracer transport in advective/diffusive flow 
Abstract: Keywords: Transittime distribution (TTD); tracer transport rates and pathways Abstract: I will explain the concept of transittime distributions (TTDs) to diagnose passive tracer transport in geophysical fluids, like the Earth's ocean and atmosphere. The TTD is directly related to the Green's function to the advection/diffusion equation for the concentration of a dynamicallypassive trace substance. Diagnosing and interpreting the TTD, rather than the passive tracer field itself, focuses attention on the advective/diffusive transport properties of the underlying flow, and removes the influence of the tracer sources and sinks. The TTD therefore quantifies fundamental transport rate and pathway information about the flow. Various basic mathematical constraints on the TTD function exist, which may illuminate traditional diagnostics of tracer stirring and mixing. Applications of the TTD approach are presented in ocean circulation models, and using ocean tracer measurements.  
Thomas W. N. Haine (Johns Hopkins University)  Introduction to dynamics and tracer dispersion in
geophysical fluids (1) Geophysical fluids: phenomenology and dynamics of rotating, stratified flow. (2) Potential vorticity: Dynamic significance and kinematic interpretation. (3) Importance of mixing for maintenance of ocean pycnocline and global overturning circulation: ocean energetics, a little on thermocline theories and/or Sandstrom's theory. (4) Tracer Observations in the ocean (and atmosphere): Turbulent mixing from dye releases, maybe something on surface stirring/mixing diagnostics from floats. (5) Tracer cascades: theory and observational support. 
Abstract: No Abstract  
Kenneth E. Hinson (University of North Carolina  Charlotte)  Braid indices in a class of closed braids 
Abstract: A longstanding problem in knot theory concerns the additivity of crossing numbers of links under the connected sum operation. It is conjectured that if A and B are links, then Cr(A#B)=Cr(A)+Cr(B), but so far this has been proved only for certain classes of links. One such class is the zerodeficiency links, which includes some alternating links and some nonalternating, such as torus knots. In this paper the known realm of zerodeficiency links is expanded to include some cases of links represented by alternating closed braids. It is shown that for a link L represented by a reduced, alternating, kstring closed braid diagram D having at most three sequences of consecutive crossings between each pair of adjacent strings, the braid index of L is k. This result makes use of a wellknown property of the HOMFLY polynomial, which provides a lower bound for the braid index of a link. It is then seen that the deficiency of L is zero. It seems likely that this result can be extended to more complex alternating closed braids.  
Jeffrey Hunt (University of Iowa)  High school level introduction to knots 
Abstract: Joint work with Bruce MacTaggart. Our educational lesson plans focus on elementary properties of knots and are meant to be a miniunit in basic knot theory for high school students. There are five total lessons in our introductory unit with a summative assessment on the fifth day. The lessons address knot notation, basic definitions, knot equivalence, and knot arithmetic. There are also various activities with handson manipulatives for modeling knots and activities involving the program KnotPlot. We believe that since knot theory is a relatively new field of both mathematics and biology it is important to generate interest with younger mathematics students.  
Traian Iliescu (Virginia Polytechnic Institute and State University)  Bridging the Boussinesq and primitive equations through spatiotemporal filtering 
Abstract: For many realistic geophysical flows, the numerical discretization of the Boussinesq equations yields a prohibitively high computational cost. Thus, a significant research effort has been directed at generating mathematical models that are more computationally efficient than the Boussinesq equations, yet are physically accurate. The tool of choice in generating these simplified models has been scaling. In this note, we put forth spatiotemporal filtering as an alternative methodology for generating simplified mathematical models for the ocean and atmosphere. In particular, we show that spatiotemporal filtering represents a natural approach for bridging the Boussinesq equations and the primitive equations.  
Anthony José Kearsley (National Institute of Standards and Technology)  Optimal chemical spectroscopy 
Abstract: Chemical spectroscopy is an invaluable tool in commerce, public safety, health care, national security, and scientific research. In most cases a measurement expert with considerable experience using an illdefined catalog of heuristic rules is required to optimize the instrument and to interpret the data. Using an expert is expensive, not always reproducible, and introduces uncontrolled bias to the measurement process. Numerical algorithms for nonlinear optimization can supplement, and perhaps even replace, the knowledge of the expert operator. I will discuss my work with one of the most complex and fastest growing of the new chemical spectroscopies: matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI TOF MS). This technique finds broad application in both the biological and materials sciences, from drug discovery to the development of high performance plastics. I will demonstrate the application of an optimization method applied to the analysis of a synthetic polymer, one of the most difficult species to analyze by MALDI TOF MS.  
Shane Keating (New York University)  Homogenization and mixing measures for a replenishing passive scalar field 
Abstract: The efficiency with which an incompressible flow mixes a passive scalar field that is continuously replenished by a steady sourcesink distribution has been quantified using the suppression of the mean scalar variance below the value it would attain in the absence of the stirring. We examine the relationship this mixing measure has to the effective diffusivity obtained from homogenization theory, particularly establishing precise connections in the case of a stirring velocity field that is periodic in space and time and varies on scales much smaller than that of the source. We explore theoretically and numerically via the ChildressSoward family of flows how the mixing measures lose their linkage to the homogenized diffusivity when the velocity and source field do not enjoy scale separation. Some implications for homogenizationbased parameterizations of mixing by flows with finite scale separation are discussed.  
Rich R. Kerswell (University of Bristol)  Setting limits on turbulence  balancing rigor with practicality 
Abstract: Keywords: Turbulent energy dissipation, eddy viscosity, stability Abstract: Variational techniques have been successful in establishing limits on transport in turbulent flow systems (e.g heat in convection, mass in pressuredriven shear flow or momentum in boundarydriven flows). However, there is typically a significant discrepancy between the limit derived and observations as well as a disconnect between the theoretical `optimal flow' solution and what is actually seen. After giving examples of this, I will discuss some past work directed at closing this gap and motivate the use of plausible stability criteria.  
Alexander Kiselev (University of Wisconsin)  Mixing and enhanced relaxation in fluid flows 
Abstract: Keywords: passive scalar, enhanced diffusion, mixing properties Abstract: We consider passive scalar equation on a compact domain or manifold. The fluid flow can aid diffusion and increase the speed of convergence of the initial distribution to its average. We consider either stationary or time periodic flows, and derive a sharp characterization of flows that are particularly effective in enhancing the relaxation speed to mean value. The characterization links enhanced relaxation with spectral properties of the dynamical system generated by flow. The results also provide an indication that time dependence of the flow may improve relaxation enhancing properties. Methods used involve a mix of PDE techniques and functional analysis. A key role is played by estimates similar to ones used in quantum dynamics to measure the rate of wavepacket propagation. The talk is based on works joint with P. Constantin, L. Ryzhik, R. Shterenberg and A. Zlatos.  
Peter R. Kramer (Rensselaer Polytechnic Institute)  Mathematical models and methods for characterizing turbulent diffusion 
Abstract: No Abstract  
Matt Mastin (University of Georgia)  Symmetries of knots and links 
Abstract: Two links are equivalent if, roughly speaking, one can be physically deformed into the other. However, we have a choice as to what information we are keeping track of. For example, if we label the components of a link we could ask whether or not the components can be permuted. A labeling of components could arise naturally in application, for example if the components are different polymers. The poster describes a method of recording all of the symmetry information of links as a certain group. We also preview an upcoming paper in which the symmetry groups for prime links through 8 crossings are computed and discuss future directions including the tabulation of composite links.  
Andrea Mazzino (Università di Genova)  Miscible and immiscible RayleighTaylor turbulence 
Abstract: The Rayleigh–Taylor (RT) instability is a fluidmixing mechanism occurring at the interface between two fluids of different density when subjected to an external acceleration. The relevance of this mixing mechanism embraces several phenomena occurring in different contexts: astrophysical supernovae and solarflare development are some examples. Although this instability has been known since 1883, much remains unknown especially on the turbulent regime. A deeper understanding of the mechanism of flows driven by RT instability would thus shed light on the many processes that underpin fully developed turbulence. Along this direction, we performed 2D and 3D direct numerical simulations in order to investigate the statistical properties of turbulent mixing in both miscible and immiscible situations. An introduction to this instability will be provided and some of our numerical results discussed.  
Richard M. McLaughlin (University of North Carolina)  Passive scalar advection in parallel shear ﬂows: WKBJ mode sorti on intermediate times and the evolution of skewness 
Abstract: Keywords: mixing, shear dispersion, Taylor dispersion Abstract: The evolution of a passive scalar diffusing in simple parallel shear flows is a problem with a long history. In 1953, GI Taylor showed theoretically and experimentally that on long times, the passive scalar experiences an enhanced diffusion in the longitudinal direction. On shorter times the scalar evolution is anomalous, characterized by second moments growing faster than linear in time as we show by analysis of the stochastic differential equations underlying the passive scalar equation. The spatial structures associated with this intermediate time evolution are predicted using WKBJ analysis of an associated nonself adjoint eigenvalue problem. This analysis predicts a sorting of wall modes and interior modes with specific predictions of the decay and propagation rates as a function of the Peclet number. Monte Carlo simulations demonstrate nontrivial skewness evolution, and skewness is studied in the new WKBJ modes. Time permitting, new behavior distinguishing channel from pipe flow will be presented along with comparisons between some of these predictions and experiments in the pipe geometry. This is joint work with Roberto Camassa, Zhi Lin, Keith Mertens, Nick Moore, and Claudio Viotti.  
Igor Mezic (University of California, Santa Barbara)  Mixing: Visualization, norms, and control 
Abstract: Keywords: mixing, mixnorm, optimal stirring, ergodicity Abstract: I will discuss several issues in analyzing kinematics of a purely advective mixing process: 1) Determine whether the scalar quantity, such as dye, introduced into the flow field is  asymptotically  in time thoroughly mixed. 2) Determine how good is the mixture at any finite time. 3) Provide methods for openloop optimization or feedback control of the mixture. The concept of ergodic partition allows us to discuss 1) precisely, and I will discuss some new results that allow us to compute it effectively. Concerning 2), the problem of an effective norm for mixing has attracted a lot of work over the last decade. I will discuss one family of norms  the so called mixnorm that connects to negative Sobolev space norms  that allows us to pursue study of opimization and control, thus covering 3). I will also discuss the question of ergodicity of a system and how to measure it. This is a departure from the standard offon definition of ergodicity providing a measure of how close to ergodicity a system is. In all of the above, ergodic theory plays a prominent role.  
Paul Milewski (University of Wisconsin)  Dynamics of shallow water layer models: Stability, wave breaking and mixing 
Abstract: Keywords: Shallow water, Layer model, hydraulic jumps, shocks, mixing, stability Abstract: Shallowfluid models are often the first step in modeling many geophysical flows. These models apply when the horizontal scales of motion are much larger than the vertical scales. For a single fluid layer with a freesurface, the shallow water approximation results in hyperbolic equations which are well understood and broadly applied. Generically, waves steepen and break creating hydraulic jumps which satisfy the PDEs in a weak sense. Physically one must ensure that certain conserved quantities  usually mass and momentum  are preserved across shocks. For the single layer case this results in a prediction of the small scale energy dissipation at the shock. In layered shallow water models the situation is complicated by at least two issues: that the flow may be shear unstable (the KelvinHelmholtz instability), and that breaking waves may mix the fluids. We shall discuss some physically motivated mathematical results on these issues.  
Dongjuan Niu (Capital Normal University)  Postdoc seminar: Coupled boundary layers for the primitive equations of atmosphere 
Abstract: In this talk I will discuss the boundary layers problems of the primitive equations of atmosphere. It is proved that, for wellprepared initial data, the smooth solutions of the primitive equations converge to smooth solutions of quasigeostrophic equations as the Rossby number, the vertical viscosity and the vertical heat conductivity tend to zero. The new ingredient is that the velocity boundary layer and thermal layer are considered simultaneously.  
Alexei Novikov (Pennsylvania State University)  Exit time problem in an incompressible flow 
Abstract: Consider a Brownian particle in a deterministic timeindependent incompressible flow in a bounded domain. We are interested how flow affects the expected exit time, the time the particle needs to reach the boundary of the domain. In particular, whether the presence of the flow decreases the maximum of this expected exit time. One would expect that any stirring improves mixing, thus decreasing the expected exit time. We will show that generally it is not true in two dimensions. This is a joint work with G.Iyer, L.Ryzhik, and A.Zlatos.  
Mary Therese Padberg (University of Iowa), Gregory Witt (University of Iowa)  Energetics of DNA tangling in complex nucleoprotein assemblies 
Abstract: Tangle analysis, a branch of mathematical knot theory, in conjunction with difference topology experiments has become a powerful emerging approach for the analysis of complex nucleoprotein assemblies containing DNA loops. A tangle consists of strings properly embedded in a 3dimensional ball. The protein complex can be thought of as a 3D ball while the DNA segments bound by the protein complex can be thought of as strings embedded within the ball. At present, tangle analysis can only provide information about 2dimensional diagrams representing the topology of DNA bound within a protein complex. Many DNA geometries can be consistent with a particular topological solution, however, limiting the value of tangle analysis in deducing biological mechanism and function. In addition, many problems of interest do not yield unique tangle solutions. Information about the relative energies of geometric solutions is badly needed to evaluate the plausibility of a particular mathematical solution both physically and biologically. We will demonstrate preliminary software for determining likely DNA geometries consistent with proteinbound DNA topologies.  
Juliet Portillo (San Francisco State University)  Invariance of the sign of the average space writhe of free and confined knotted polygons 
Abstract: Our group studies topological properties of DNA molecules in solution. We consider highly compacted models of knotted DNA, such as DNA extracted from P4 phages. Circular DNA molecules are modeled as selfavoiding polygons (SAPs) in threedimensional space. Using different Monte Carlo algorithms, we sample the space of knotted SAPs and study knotting probabilities. To better understand how DNA knotting is affected in confined environments, we generate knotted configurations confined inside small spheres. Writhe is a geometric invariant that measures the entanglement complexity of a given configuration. A comparison of the writhe of confined versus free knots suggests that the sign of the average writhe is invariant for each chiral knot type under varying polygonal lengths on the simple cubic lattice and in R3. We propose that the sign of the average space writhe is a robust measure of knot chirality.  
François W. Primeau (University of California, Irvine)  The inverse problem of inferring transittime distributions from tracer observations in the ocean 
Abstract: Keywords: Transittime distribution (TTD); tracer transport; inverse problem; maximumentropy deconvolution Abstract: I will discuss the inverse problem of inferring the Green's function for advectivediffusive transport (also known as the transittime distribution) from tracer observations. Tracers with different boundary conditions and/or different radioactive decay rates probe different transport pathways and timescales. Using multiple tracers in combination can therefore help constrain the full transittime distribution (TTD). I will review two inversion methodologies applicable to ocean tracer measurements, one based on a parametric model for the TTD and one based on a more flexible maximumentropy deconvolution approach. Because the oceanographic inverse problem is grossly underdetermined an important focus of this talk will be on quantifying the uncertainty associated with the inversion results.  
Nancy Reid (University of Toronto)  Can chocolate save your life? 
Abstract: This question appeared in a recent newspaper headline, but was based on a study involving only 14 people. How can we interpret the statistics behind headlines? What does statistically significant really mean? How do statistics get manipulated to further an agenda? The field of statistics is essential to understanding most current issues. It informs economics, health care, and environmental protection. The speaker calls statistics mathematical social work; it helps science progress, so it is important to understand its power.  
Juan Mario Restrepo (University of Arizona)  Jet dynamics in stratified media 
Abstract: Keywords: jet, buoyancy, stratified flow, stability Abstract: I discuss the flow structure and stability of a planar saline jet descending into a stable, densitystratified fluid. The jet retains its slender shape, largely due to the low salt diffusion. As the jet descends it entrains fresher water due to the relatively high mechanical viscous effects, when these are compared to inertial effects. This fresher water forms a recirculation cell. The jet exhibits a rapid acceleration on release, then deceleration, as it encounters the more dense surrounding fluid, and stops at a location much higher than the neutral buoyancy point. I will recount preliminary work aimed at explaining the fluid dynamics of the jet: Stratification, mechanical diffusion and nonlinear inertial effects, as well as salt diffusion are all found to be crucial to the dynamics. I will also summarize our work on characterizing the basic instability modes of the jet by numerical means. We successfully captured the inception of the most salient symmetric and antisymmetric instabilities and their dependence on the Reynolds number and the nondimensional stratification gradient number. This jet, though deceptively simple, is far from well understood. I will enumerate key dynamic aspects that are beyond our present understanding and worthy of further study due to their relevance to other important physical phenomena. This is joint work with Sam Schofield, Los Alamos National Laboratory, with contributions from Adriana Pesci and Raymond Goldstein, Cambridge University.  
Bertrand Rollin (Los Alamos National Laboratory)  On the effect of initial velocity field and phase shifting of an initial binary perturbation for RayleighTaylor instability 
Abstract: Starting (initial) conditions (ICs) can influence the development of hydrodynamic turbulence and material mixing in buoyancy driven flows. The overall goal of our research is to determine the extent to which starting conditions can be used to predict and design turbulent transport/material mixing. In particular, this work studies the effect of the initial velocity field and phase shifting on a binary initial perturbation. Results of an experimental investigation in which precisely defined initial conditions have been prescribed are presented. These experimental results serve as references that we try to match as closely as possible with numerical simulations. Our simulations show that the initial velocity field drives the growth of the initial perturbation in this experiment. Also, a “leaning” of the growing flow structures observed in the experiment is captured by the simulations, and linked to the phase shift.  
Bonita V. Saunders (National Institute of Standards and Technology)  Applying numerical grid generation to the visualization of complex function data 
Abstract: Numerical grid generation, that is, structured grid generation, is the development of a generalized curvilinear coordinate system. Originally designed for solving computational fluid dynamics problems over oddly shaped domains, structured techniques have competed with various unstructured methods such as Voronoi or Delaunay triangulations and quadtree designs. However, the effectiveness of a given grid often depends on how it is used. For complex function visualization problems, the grid generation technique may be less important than how closely the grid lines follow the contours of the function. This talk looks at the use of a tensor product Bspline mapping to generate a boundary/contour fitted mesh that captures significant attributes such as zeros, poles, branch cuts and other singularities when the mesh is used to plot a complex function surface. This work has been used to create over 200 interactive 3D visualizations of complex function surfaces for the NIST Digital Library of Mathematical Functions (DLMF). The NIST DLMF and its hardcopy version, the NIST Handbook of Mathematical Functions, will replace the wellknown NBS Handbook of Mathematical Functions edited by Abramowitz and Stegun and first published in 1964.  
Robert Glenn Scharein (San Francisco State University)  Minimal step number of cubic lattice knots in thin slabs 
Abstract: We present provisional data on the minimal step number of cubic lattice knots confined to a thin slab. In particular, we investigate thin slabs of thickness 1, 2 and 3. For most knot types, several ergodicity classes are found, often with dramatically different minimal step numbers. We discuss the number of distinct minimal step embeddings found within each class. We show that in the case of the 1slab, arbitrarily high step number representatives for each knot type may be found that are irreducible within the 1slab. Finally, we examine recurring patterns across the entire database of minimal step knots, both in thin slabs and for the unconstrained case.  
Joerg Schumacher (Ilmenau University of Technology)  Numerical studies in shallow moist convection 
Abstract: Convective turbulence with phase changes and latent release is an important dynamical process in the atmosphere of the Earth which causes, e.g., the formation of clouds. Here we study moist convection in simplified setting  shallow and nonprecipitating moist RayleighBenard convection with a piecewise linear thermodynamics on both sides of the phase boundary. The presented model is a first nontrivial extension of the classical dry RayleighBenard convection. The equations of motion and the fully developed turbulent dynamics in very flat Cartesian cells are discussed.  
Emily F. Shuckburgh (British Antarctic Survey)  Mixing by eddies in the atmosphere and ocean 
Abstract: Keywords: eddy diffusivity, conserved tracer, reactive tracer Abstract: Eddies have an important role in transport and dynamical processes in the atmosphere and ocean. They influence the distribution of chemical species and are responsible for driving mean flows. I will discuss the quantification of eddy effects in the atmosphere and ocean. I will focus in particular on two problems. The first is how to quantify the geographic (latitudelongitude) variation of eddy diffusivity of a conserved tracer in such flows. I will describe two different techniques and discuss the implications of the results for an atmospheric and an oceanic case. The second is how to quantify the effects of eddies on the distribution of a reactive tracer. I will take the example of different tracers at the sea surface (temperature, salinity, chlorophyll, etc). Eddy stirring directly influences the distribution of such tracers, but smallscale eddies in the ocean can also influence airsea interactions and I will describe how this latter effect may be quantified.  
K. Shafer Smith (New York University)  The threedimensional structure of turbulent geostrophic stirring 
Abstract: Keywords: geostrophic turbulence, baroclinic instability, stirring and mixing Abstract: Turbulent flows generated by baroclinic instability develop strong nearlybarotropic vortices and lateral strain fields, with energy accumulating in large horizontal and vertical scales. Nevertheless, away from boundaries these flows simultaneously generate strong vertical shear and vertical strain variance on small scales, resulting from the threedimensional forward cascade of potential enstrophy. It is shown that the combined action of strain and shear generates tracer filaments that, on average, maintain a scaleindependent aspect ratio proportional to N/f. The result is a submesoscale coupling between vertical mixing and horizontal stirring that allows vertical diffusion to effectively absorb the laterally driven cascade of tracer variance. Nearer the ocean's surface, geostrophic turbulence changes its character: the turbulent dynamics becomes dominated by a forward cascade of buoyancy, causing the energy spectrum to flatten, and the tracer variance spectrum to steepen. In the upperocean where the stratification is weak, this results in a ubiquitous generation of lateral density fronts. These dynamically active fronts are primed by mesoscale stirring, but provide a pathway to interaction with smallerscale turbulent processes. I'll present results from a series of simulations demonstrating the dynamics of both regimes described above.  
Wenbo Tang (Arizona State University)  Lagrangian dynamics in stochastic inertiagravity waves 
Abstract: We perturb the analytic deterministic solution of inertiagravity waves with stationary random noise and solve for the FokkerPlanck equation to study the evolution in time of the probability density function of passive tracers in such a flow. We find that at initial times the probability density closely follows the nonlinear background flow and nontrivial Stokes drift ensues as a result. Over finite time, we measure chaotic mixing based on the stochastic mean flow and identify nontrivial mixing structures of passive tracers, as compared to their absence in the deterministic flow. At later times, when the probability density field spreads out to sample larger regions, the mean Stokes drift approaches an asymptotic value, indicating suppression of Lagrangian mixing at long timescales. However, the skewness of the probability density remains nonGaussian even at large times.  
JeanLuc Thiffeault (University of Wisconsin)  Do fish stir the ocean? 
Abstract: Keywords: stirring, mixing, biomixing, Brownian motion. Abstract: As fish or other bodies move through a fluid, they stir their surroundings. This can be beneficial to some fish, since the plankton they eat depends on a wellstirred medium to feed on nutrients. Bacterial colonies also stir their environment, and this is even more crucial for them since at small scales there is no turbulence to help mixing. It has even been suggested that the total biomass in the ocean makes a significant contribution to largescale vertical transport, but this is still a contentious issue. We propose a simple model of the stirring action of moving bodies through both inviscid and viscous fluids. In the dilute limit, this model can be solved using Einstein and Taylor's formula for diffusion (Brownian motion). We compare to direct numerical simulations of objects moving through a fluid. This is joint work with Steve Childress and George Lin.  
Becca Thomases (University of California, Davis)  A Stokesian viscoelastic flow: Transition to mixing and oscillations 
Abstract: Keywords: OldroydB, viscoelastic, instabilities, mixing Abstract: To understand observations of low Reynolds number mixing and flow transitions in viscoelastic fluids, we study numerically the dynamics of the OldroydB viscoelastic fluid model. The fluid is driven by a simple timeindependent forcing that creates a cellular flow with extensional stagnation points. We find that at O(1) Weissenberg number these flows lose their slaving to the forcing geometry of the background force, become oscillatory with multiple frequencies, and show continual formation and destruction of smallscale vortices. This drives flow mixing. These new flow states are dominated by a single large vortex, which may be stationary or move persistently from cell to cell. Increasing the number of degrees of freedom by increasing the number of driving cells broadens the temporal frequency spectrum and yields richer dynamics with no persistent vortices and improved fluid mixing.  
Giordano Tierra Chica (University of Sevilla)  Superconvergence for the 3D NavierStokes 
Abstract: This work is devoted to study the stability and error estimates of a fully discrete scheme for the incompressible timedependent NavierStokes Equations in threedimensional domains. Space is discretized by using the Finite Element Method, whereas time is discretized using the Finite Difference Method. We introduce an extension to mixed elliptic problems of the negativenorm estimates for uniformly elliptic problems. Using this extension, we prove some superconvergence results in space for velocity which have been observed in several computational experiments. Furthermore, we obtain some error estimates results for the pressure without restrictions relating time and space discrete parameters.  
Vy T. Tran (University of St. Thomas)  Symmetrybreaking in cumulative measures of shapes of polymer models 
Abstract: In a thermally agitated environment, randomly generated polygons are used to model the conformations of fluctuating polymer chains. To characterize the shapes of these polygons, we created 3D density plots of the vertex distributions of families of random 6 edge polygons. The distributions give a measure of the shapes of the polygons, and our symmetrybreaking alignment procedure is not only able to reveal their average bulk shape, but also distinguish between different knot topologies and chirality. We looked at the family of 6 edge polygons, separating them by knot type, and we also looked at 6 edge open chains.  
Rolland Trapp (California State University)  Polygonal cable links 
Abstract: Given a polygonal knot we present an efficient construction of polygonal cables of the knot. The construction is applied to polygonal unknots to obtain results about stick numbers of torus knots. In particular, we show that (2,q) torus links can be constructed with about twothirds q sticks. This is used to show that for q greater than 14, minimal stick representatives of (2,q) torus links are "supercoiled". Finally we show that for 2p < q < 3p the stick number of (p,q) torus links is 4p.  
YueKin Tsang (University of California, San Diego)  Fast chemical reactions in chaotic flows: Reaction rate and mixdown time 
Abstract: We study the effect of chaotic flows on the progress of fast bimolecular reactions. Simulations show that the reactant concentration decays exponentially and then crosses over to the algebraic law of chemical kinetics in the final stage of the reaction. By transforming the reactive mixing problem to an equivalent passive scalar problem, we make prediction to the crossover time and the overall reaction rate. Depending on the relative length scale between the velocity and the concentration fields, the overall reaction rate is either related to the distribution of the finitetime Lyapunov exponent or given in terms of an effective diffusivity. Preliminary results on a variation of this problem in which the reactants are initially isolated from one another is also presented. Here, we focus on the mixdown time, i.e. the time taken for the flow to bring the reactants into contact, and its dependence on the various length scales in the system.  
Alexandra Tzella (École Normale Supérieure)  Spatial structures of chaotically advected reactive tracers: The role of a delay time 
Abstract: Keywords: reactive flows, chaos, structure functions, Holder exponents, delay differential equations, Lyapunov exponents Abstract: Motivated by the spatial heterogeneity observed in plankton distributions in the mesoscale ocean, we examine the stationarystate spatial structure of reacting tracer fields, for the case for which the reaction equations contain delay terms. The fields are advected by a flow that gives rise to chaotic parcel trajectories and the structures are maintained by a largescale source. Previous theoretical investigations have shown that, in the absence of delay terms and in a regime where diffusion can be neglected (large Peclet number), the structures are filamental and characterized by a single scaling regime with a Holder exponent that depends on the rate of convergence of the reactive processes and the strength of the stirring measured by the average stretching rate (Lyapunov exponent). In the presence of delay terms, we show that for sufficiently small scales all interacting fields should share the same spatial structure, as found in the absence of delay terms. However, depending on the strength of the stirring and the magnitude of the delay time, two further scaling regimes that are unique to the delay system may appear at intermediate lengthscales. An expression for the transition lengthscale dividing smallscale and intermediatescale regimes is obtained and the scaling behavior of the tracer field is explained. Finally, we discuss the dependence of the field's scaling exponents on the distribution of the stretching statistics. Joint work with P. H. Haynes.  
Jacques Vanneste (University of Edinburgh)  Modelling streaming by surface acoustic waves 
Abstract: Keywords: microfluidics, acoustic mixing, surface waves, acoustic streaming Abstract: Acoustic streaming, the generation of flow by dissipating acoustic waves, provides a promising method for flow pumping in microfluidic devices. In recent years, several groups have been experimenting with a acoustic streaming induced by leaky surface waves: (Rayleigh) surface waves excited in a piezoelectric solid interact with a small volume of fluid where they generate acoustic waves and, as result of the viscous dissipation of these waves, a mean flow. We discuss the basic mathematical model that has been employed in simulations of this type of acoustic streaming and reformulate it to account for the dynamical constraints imposed by vorticity conservation. The formulation proposed makes it clear that dissipative processes in the bulk of the fluid are essential to the streaming, and separates the Eulerian and Stokes contributions to the mean flow. Particular attention is paid to the thin boundary layer that forms at the solid/liquid interface, where both the acoustic waves and their streaming effect are best computed by asymptotic means. A simple twodimensional model of meanflow generation by surface acoustic waves is discussed as an illustration. Joint work with Oliver Buhler (Courant).  
Jacques Vanneste (University of Edinburgh)  Estimating generalised Lyapunov exponents for random flows 
Abstract: The generalised Lyapunov exponents (GLEs) quantify the growth of the separation between particles advected in fluid flows. They provide valuable information about mixing, in particular because, in some cases, the decay rate of passive scalars released a flow can be directly related to specific GLEs of this flow. Here we discuss some numerical and asymptotic methods for the estimation of the GLEs of random renewing flows (such as the alternatingsine flow) in which the particle separation is described by a product of random matrices. Specifically, we propose an importancesampling Monte Carlo algorithm as a general purpose numerical method which is both efficient and easy to implement. We also discuss asymptotic approximations for the GLEs characterising extremes of stretching.  
Xiaoming Wang (Florida State University)  Approximating the rate of heat transport 
Abstract: Keywords: convection, heat transport, Nusselt number, ConstantinDoeringHopf technique, long time statistical properties, numerical approximation, convergence of long time statistical properties Abstract: We survey a few recent results on estimating the long time averaged rate of heat transport in the vertical direction (the Nusselt number) in RayleighBénard convection. In the first half of the talk, we recall rigorous upper bounds on the Nusselt number that are of the form of Ra^{1/3} modulo logarithmic correction for both the infinite Prandtl number model and the classical Boussinesq model for convection with large but finite Prandtl number. The main technique is the ConstantinDoeringHopf approach. We also discuss the infinite Prandtl number limit in the Boussinesq model for convection, and the formal infinite Rayleigh number limit within the infinite Prandtl number model for convection. In the second half of the talk, we discuss numerical schemes (time discretization) that are able to capture the long time statistical properties of the convection problems. We first recall that the maximum long time averaged rate of heat transport in the vertical direction (true maximum Nusselt number) is a long time statistical property of the convection system. We then show that appropriate time discretizations of the systems will be able to capture the true maximum Nusselt number asymptotically. Several specific schemes that satisfy the desired properties will be presented. This numerical approach complements the ConstantinDoeringHopf approach in the sense that it provides a computational asymptotic lower bound. Noise effects will be mentioned.  
Danielle Washburn (University of Iowa)  Tangle tabulation 
Abstract: Like knots, tabulating tangles is done by crossing number. Tangles are similar to knots, but contain strings whose endpoints are "nailed down" on the boundary of a 3dimensional ball. The crossing number is the minimal number of crossings needed to draw the diagram of a knot (tangle). We will discuss some basic concepts common between knots and tangles, how to code this and issues that have arisen. Finally, we will introduce why we are interested in tabulating tangles: math biology.  
Jeffrey B. Weiss (University of Colorado)  Broadcast spawning: A new class of reactionmixing problems 
Abstract: Keywords: mixing reaction broadcast spawning coral scaling Abstract: Coral and other marine organisms reproduce through the mechanism of broadcast spawning, where egg and sperm are released at separate locations and brought together by fluid mixing and transport. Coral fertilization is particularly important because corals are threatened by anthropogenic climate change. We idealize broadcast spawning as point sources of two reacting tracers separated by a neutral fluid. This represents a new class of problems, different from wellstudied problems such as flame fronts, where two tracers fill the fluid and are separated by an interface. For the case of broadcast spawning within a vortex, we show that the vortex stirring leads to a selfsimilar solution with enhanced fertilization rates scaling as the Peclet number^{(1/3)} and reduced fertilization times scaling as the Peclet number^{(2/3)}.  
Xiaofeng Yang (University of South Carolina)  Shear cell rupture of nematic droplets in viscous fluids 
Abstract: We model the hydrodynamics of a twophase system of a nematic liquid crystal drop in a viscous fluid using an energetic variational approach with phasefield methods cite{YFLS04}. The model includes the coupled system for the flow field for each phase, a phasefield function for the diffuse interface and the orientational director field of the liquid crystal phase. An efficient numerical scheme following is implemented for the twodimensional evolution of the shear cell experiment for this initial data. We simulate the deformation and rupture of nematic droplets, identifying the formation of surface topological defects, and exploring the shear and normal stress distributions that accompany the evolution. A bipolar global defect structure, with two halfinteger surface point defects called boojums, emerges in every daughter droplet when tangential anchoring conditions are imposed together with OseenFrank distortional bulk elasticity. The fate of the original mother drop is compared for the limiting case of an immiscible viscous drop versus strength of the liquid crystal interfacial and bulk potentials.  
William Roy Young (Scripps Research Institute)  Is turbulence stable? 
Abstract: Keywords: Jet, layer, potential vorticity, betaplane, stratified turbulence, CahnHilliard equation, negative viscosity Abstract: I'll discuss two examples of uniformly forced turbulent flows in which quasisteady structures spontaneously form. This results in the intensity of turbulence becoming spatially inhomogeneous on length scales larger than those of the eddies i.e., as argued by Owen Phillips in 1972, a spatially homogeneous turbulent flow may be subject to a largescale instability. The first example is stirring a fluid with strong gravitational stability due to, for example, dissolved salt. The resulting stratified turbulence produces wellmixed layers with uniform density, separated by strongly stable steps in density. The second example is the formation of zonal jets in forceddissipative betaplane turbulence. I'll discuss the prospects of understanding these systems using models related to the CahnHilliard equation.  
William Roy Young (Scripps Research Institute)  Shear dispersion
(1) interaction of molecular diffusion with simple unidirectional shear flows (bounded and unbounded domains). (2) Limitation of the effective diffusion approximation to long times and small domains, and low moments of the tracer distribution. (3) Perhaps a geophysical example: shear diffusion in the internal gravity wave field. The vertical tracer cascade of Haynes & Anglade. (4) Some examples of "preasymptotic" anomalous shear diffusion e.g.,〈x^{2}〉 ∼ t ln t due to the noslip condition, and 〈x^{2}〉 ∼ t ^{3/2} in the example of de Marsily & Matheron. 
Abstract: No Abstract  
Lynn Zechiedrich (Baylor College of Medicine)  Biological applications that utilize DNA Topology 
Abstract: The long, rich history of topology in mathematics has proven extremely useful for the study of DNA. DNA, the genetic blueprint for life, undergoes tremendous flux as it is packaged, replicated, segregated, transcribed, recombined and repaired. Extremely long and skinny, DNA is prone to entanglement. Every time it is copied, the two resulting "daughter chromosomes" are entangled. And nearly all organisms maintain duplex DNA in a slightly underwound state. Linking number (Lk), the major descriptor for DNA apart from base pair sequence, defines the three forms of DNA topology, which are known to biologists as knots, catenanes, and supercoils. Changes in Lk have dramatic effects on biological processes. In this talk I will provide an overview of DNA topology and the biological ramifications of topology, including exciting new developments in the application to medicine. The following authors have contributed to the work: Jonathan M. Fogg_{1}, Daniel J. Catanese, Jr._{1}, Donald Schrock, II_{1}, Richard W. Deibler_{1,2,3}, Jennifer K. Mann_{1,4}, De Witt L. Sumners_{4}, Brian E. Gilbert_{1}, Youli Zu_{5}, Nianxi Zhao_{5}. _{1}Departments of Molecular Virology & Microbiology, Biochemistry and Molecular Biology, and Pharmacology, Baylor College of Medicine, Houston, TX 77025 _{2}Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, TX 77030 _{3}Department of Systems Biology, Harvard Medical School, Boston, MA 02115 _{4}Department of Mathematics, Florida State University, Tallahassee, FL 32306 _{5}Department of Pathology, The Methodist Hospital Research Institute, Houston, TX 77030 USA  
Laura K. Zirbel (University of California, Santa Barbara)  The local and global shape of regular embedded polygons: Theoretical and experimental 
Abstract: We consider $mathcal{P}_n$, the space of equilateral, nsided polygons embedded in $mathbb{R}^3$. There are several descriptions of the global shape of a polygon $P in mathcal{P}_n$, including the convex hull volume, miniball radius, asphericity and radius of gyration. We sought a description of shape that was sensitive to both local and global behavior, and to look at average trends over both the whole population of $mathcal{P}_n$, as well as ﬁnding the average over sub populations of a speciﬁc knot type. We developed two such descriptions. For a given $P in mathcal{P}_n$, we find the average of the squared distance between vertex $i$ and $i+k$ for all $1 leq i leq n$. We call this the Average Squared End to End Distance of length $k$ of $P$. Similarly, we find the squared radius of gyration for all subsegments of $P$ of length $k$, and we call the average of these values the Average Squared Radius of Gyration of length $k$ of $P$. We determine the theoretical averages of these values, taken over all of $mathcal{P}_n$, in terms of $n$ and $k$. In addition, we examine specific examples of embedded polygons, to determine the effect of knotting of these descriptions of shape. 
Farid Ait Chaalal  McGill University  4/11/2010  4/17/2010 
Douglas N. Arnold  University of Minnesota  4/1/2010  4/1/2010 
F. Javier Arsuaga  San Francisco State University  4/9/2010  4/9/2010 
Joel D. Avrin  University of North Carolina  Charlotte  4/11/2010  4/18/2010 
Gregory R. Baker  Ohio State University  4/19/2010  4/21/2010 
Nusret Balci  University of Minnesota  9/1/2009  8/31/2010 
Claude Bardos  Université de Paris VI (Pierre et Marie Curie)  2/15/2010  4/25/2010 
Lauren M. Beaumont  University of Iowa  4/9/2010  4/10/2010 
Jennifer Beichman  University of Michigan  9/1/2009  5/31/2010 
Michael Berglund  University of Georgia  4/9/2010  4/11/2010 
Andrew Joel Bernoff  Harvey Mudd College  4/6/2010  4/11/2010 
Hakima Bessaih  University of Wyoming  4/11/2010  4/17/2010 
Anusha Bharadwaj  University of Texas at Dallas  4/9/2010  4/11/2010 
Animikh Biswas  University of North Carolina  Charlotte  4/10/2010  4/15/2010 
Katarina Bodova  Komensky (Comenius) University of Bratislava  4/11/2010  4/17/2010 
Guido Boffetta  Università di Torino  4/10/2010  4/16/2010 
Olus N. Boratav  Corning Incorporated  4/10/2010  4/16/2010 
James Joseph Brannick  Pennsylvania State University  4/10/2010  4/15/2010 
Susan Brooks  University of Iowa  4/9/2010  4/11/2010 
Dorothy E. Buck  Imperial College London  4/9/2010  4/9/2010 
MariaCarme T. Calderer  University of Minnesota  9/1/2009  6/30/2010 
Jason Cantarella  University of Georgia  4/9/2010  4/9/2010 
Colm P. Caulfield  University of Cambridge  4/10/2010  4/16/2010 
Chi Hin Chan  University of Minnesota  9/1/2009  8/31/2010 
Xianjin Chen  University of Minnesota  9/1/2008  8/31/2010 
Alina Chertock  North Carolina State University  4/11/2010  4/16/2010 
Stephen Childress  New York University  4/11/2010  4/16/2010 
Gregory P. Chini  University of New Hampshire  4/10/2010  4/17/2010 
Ivan Christov  Northwestern University  4/11/2010  4/16/2010 
John Collins  San Francisco State University  4/9/2010  4/11/2010 
Gedeon Dagan  Tel Aviv University  4/11/2010  4/15/2010 
Domenico D'Alessandro  Iowa State University  4/15/2010  6/30/2010 
Isabel K. Darcy  University of Iowa  4/9/2010  4/11/2010 
Elizabeth Denne  Smith College  4/9/2010  4/9/2010 
Yuanan Diao  University of North Carolina  Charlotte  4/9/2010  4/9/2010 
Charles R. Doering  University of Michigan  8/15/2009  6/15/2010 
Doug Dokken  University of St. Thomas  4/12/2010  4/16/2010 
Michael Dupuis  University of St. Thomas  4/9/2010  4/9/2010 
Robert S. Eisenberg  Rush University Medical Center  4/11/2010  4/13/2010 
Claus Ernst  Western Kentucky University  4/9/2010  4/9/2010 
Randy H. Ewoldt  University of Minnesota  9/1/2009  8/31/2010 
Jin Feng  University of Kansas  4/11/2010  4/17/2010 
Aldo Fiori  Università di Roma "La Sapienza"  4/10/2010  4/16/2010 
Natasha Flyer  National Center for Atmospheric Research  4/11/2010  4/14/2010 
Eliot Fried  McGill University  4/11/2010  4/17/2010 
John R. Froehlig  University of Iowa  4/9/2010  4/11/2010 
Boris Gershgorin  New York University  4/11/2010  4/16/2010 
Stefan M. Giovan  University of Texas at Dallas  4/9/2010  4/11/2010 
Michael D. Graham  University of Wisconsin  4/11/2010  4/16/2010 
Thomas C. Hagen  University of Memphis  4/9/2010  4/17/2010 
Thomas W. N. Haine  Johns Hopkins University  4/10/2010  4/16/2010 
Peter Haynes  University of Cambridge  4/10/2010  4/16/2010 
Kenneth E. Hinson  University of North Carolina  Charlotte  4/9/2010  4/11/2010 
TzyyLeng Allen Horng  Feng Chia University  4/11/2010  4/17/2010 
Jeffrey Hunt  University of Iowa  4/9/2010  4/11/2010 
Vera Mikyoung Hur  University of Illinois at UrbanaChampaign  2/18/2010  5/31/2010 
Yunkyong Hyon  University of Minnesota  9/1/2008  8/31/2010 
Traian Iliescu  Virginia Polytechnic Institute and State University  4/11/2010  4/16/2010 
Mark Iwen  University of Minnesota  9/1/2008  8/31/2010 
Gautam Iyer  Stanford University  4/11/2010  4/16/2010 
Srividhya Jeyaraman  University of Minnesota  9/1/2008  8/31/2010 
Lijian Jiang  University of Minnesota  9/10/2008  8/31/2010 
Garrett Jones  University of Iowa  4/9/2010  4/11/2010 
Mihailo Jovanovic  University of Minnesota  9/11/2009  6/10/2010 
Ning Ju  Oklahoma State University  1/4/2010  6/30/2010 
Anthony José Kearsley  National Institute of Standards and Technology  4/29/2010  5/1/2010 
Shane Keating  New York University  4/10/2010  4/16/2010 
Markus Keel  University of Minnesota  7/21/2008  6/30/2010 
James Patrick Kelliher  University of California, Riverside  4/11/2010  4/15/2010 
Thomas W Kephart  Vanderbilt University  4/9/2010  4/9/2010 
Rich R. Kerswell  University of Bristol  4/10/2010  4/16/2010 
Hyejin Kim  University of Minnesota  9/1/2009  8/31/2010 
Alexander Kiselev  University of Wisconsin  4/11/2010  4/16/2010 
Tomasz Komorowski  Marie CurieSkłodowska University  4/11/2010  4/16/2010 
Pawel Konieczny  University of Minnesota  9/1/2009  8/31/2010 
Peter R. Kramer  Rensselaer Polytechnic Institute  4/10/2010  4/16/2010 
Alexander Kurganov  Tulane University  4/11/2010  4/16/2010 
Juan C. Latorre  Freie Universität Berlin  4/11/2010  4/16/2010 
Norman Lebovitz  University of Chicago  4/11/2010  4/16/2010 
ChiunChang Lee  National Taiwan University  10/22/2009  6/30/2010 
YoungJu Lee  Rutgers University  4/10/2010  4/17/2010 
Stephen D. Levene  University of Texas at Dallas  4/9/2010  4/10/2010 
Marta Lewicka  University of Minnesota  9/1/2009  6/30/2010 
Congming Li  University of Colorado  1/11/2010  6/15/2010 
Yongfeng Li  University of Minnesota  9/1/2008  8/31/2010 
TaiChia Lin  National Taiwan University  4/8/2010  4/16/2010 
Zhi (George) Lin  University of Minnesota  9/1/2009  8/31/2010 
Chun Liu  University of Minnesota  9/1/2008  8/31/2010 
Stefan Llewellyn Smith  University of California, San Diego  4/11/2010  4/16/2010 
Ellen K. Longmire  University of Minnesota  9/1/2009  6/30/2010 
Krishnan Mahesh  University of Minnesota  9/1/2009  6/30/2010 
Kara Lee Maki  University of Minnesota  9/1/2009  8/31/2010 
Vasileios Maroulas  University of Minnesota  9/1/2008  8/31/2010 
Nader Masmoudi  New York University  4/13/2010  4/16/2010 
Matt Mastin  University of Georgia  4/9/2010  4/11/2010 
Sarah Matz  University of Wisconsin  4/9/2010  4/18/2010 
Andrea Mazzino  Università di Genova  4/10/2010  4/16/2010 
Anna L. Mazzucato  Pennsylvania State University  1/12/2010  6/11/2010 
Richard M. McLaughlin  University of North Carolina  4/11/2010  4/16/2010 
Igor Mezic  University of California, Santa Barbara  4/14/2010  4/16/2010 
Paul Milewski  University of Wisconsin  4/9/2010  4/13/2010 
Kenneth C. Millett  University of California, Santa Barbara  4/9/2010  4/9/2010 
Yoichiro Mori  University of Minnesota  9/1/2009  6/30/2010 
Benson Muite  University of Michigan  4/11/2010  4/16/2010 
Dongjuan Niu  Capital Normal University  4/1/2010  6/15/2010 
Alexei Novikov  Pennsylvania State University  4/11/2010  4/16/2010 
Samuel Segun Okoya  Obafemi Awolowo University  2/15/2010  5/15/2010 
Cecilia OrtizDuenas  University of Minnesota  9/1/2009  8/31/2010 
Hans G. Othmer  University of Minnesota  9/1/2009  6/30/2010 
Carolyn Ann Otto  Rice University  4/9/2010  4/9/2010 
Mary Therese Padberg  University of Iowa  4/9/2010  4/11/2010 
Jason Parsley  Wake Forest University  4/9/2010  4/9/2010 
Benoit Pausader  Brown University  4/19/2010  4/25/2010 
Grigorios A. Pavliotis  Imperial College London  4/10/2010  4/18/2010 
Leonid Piterbarg  University of Southern California  4/12/2010  4/17/2010 
Juliet Portillo  San Francisco State University  4/9/2010  4/11/2010 
Candice Renee Price  University of Iowa  4/8/2010  4/12/2010 
François W. Primeau  University of California, Irvine  4/11/2010  4/16/2010 
Michelle Radtke  University of Minnesota  4/10/2010  4/10/2010 
Teresita RamirezRosas  Grand Valley State University  4/9/2010  4/10/2010 
Eric J. Rawdon  University of St. Thomas  4/9/2010  4/10/2010 
Nancy Reid  University of Toronto  4/21/2010  4/23/2010 
Juan Mario Restrepo  University of Arizona  8/11/2009  6/15/2010 
Bertrand Rollin  Los Alamos National Laboratory  4/10/2010  4/16/2010 
Fadil Santosa  University of Minnesota  7/1/2008  6/30/2011 
Bonita V. Saunders  National Institute of Standards and Technology  4/8/2010  4/10/2010 
Robert Glenn Scharein  San Francisco State University  4/8/2010  4/10/2010 
Arnd Scheel  University of Minnesota  9/1/2009  6/30/2010 
Joerg Schumacher  Ilmenau University of Technology  4/11/2010  4/17/2010 
Sherry Euvette Scott  Marquette University  4/10/2010  4/17/2010 
George R Sell  University of Minnesota  9/1/2009  6/30/2010 
Tsvetanka Sendova  University of Minnesota  9/1/2008  8/31/2010 
Shuanglin Shao  University of Minnesota  9/1/2009  8/31/2010 
Tiffany Shaw  New York University  4/11/2010  4/16/2010 
Amy Shen  University of Washington  4/11/2010  4/17/2010 
Jie Shen  Purdue University  4/6/2010  4/16/2010 
Emily F. Shuckburgh  British Antarctic Survey  4/11/2010  4/16/2010 
Dianne Smith  University of Iowa  4/9/2010  4/10/2010 
Christine E. Soteros  University of Saskatchewan  4/9/2010  4/9/2010 
Edward A. Spiegel  Columbia University  4/10/2010  4/16/2010 
Daniel Spirn  University of Minnesota  9/8/2009  6/1/2010 
Panagiotis Stinis  University of Minnesota  9/1/2009  6/30/2010 
De Witt L. Sumners  Florida State University  4/9/2010  4/12/2010 
Vladimir Sverak  University of Minnesota  9/1/2009  6/30/2010 
Wenbo Tang  Arizona State University  4/11/2010  4/16/2010 
JeanLuc Thiffeault  University of Wisconsin  9/1/2009  6/30/2010 
Becca Thomases  University of California, Davis  2/9/2010  6/15/2010 
Giordano Tierra Chica  University of Sevilla  4/6/2010  7/21/2010 
Edriss Saleh Titi  University of California  3/28/2010  6/18/2010 
Chad Michael Topaz  Macalester College  9/1/2009  6/30/2010 
Nathan Totz  University of Michigan  4/18/2010  4/25/2010 
Vy T. Tran  University of St. Thomas  4/9/2010  4/9/2010 
Rolland Trapp  California State University  4/9/2010  4/11/2010 
YueKin Tsang  University of California, San Diego  4/10/2010  4/17/2010 
Alexandra Tzella  École Normale Supérieure  4/9/2010  4/16/2010 
Jacques Vanneste  University of Edinburgh  4/11/2010  4/16/2010 
Mariel Vazquez  San Francisco State University  4/9/2010  4/9/2010 
Changyou Wang  University of Kentucky  9/1/2009  6/15/2010 
Guanyu Wang  University of Iowa  4/9/2010  4/11/2010 
Xiaoming Wang  Florida State University  1/5/2010  5/14/2010 
Danielle Washburn  University of Iowa  4/9/2010  4/11/2010 
Darryn Waugh  Johns Hopkins University  4/11/2010  4/16/2010 
Jeffrey B. Weiss  University of Colorado  4/11/2010  4/16/2010 
Stuart Whittington  University of Toronto  4/9/2010  4/9/2010 
Kraig Winters  University of California, San Diego  4/11/2010  4/17/2010 
Gregory Witt  University of Iowa  4/9/2010  4/11/2010 
Celestine Woodruff  Florida State University  4/11/2010  4/17/2010 
Sijue Wu  University of Michigan  9/1/2009  6/5/2010 
Wei Xiong  University of Minnesota  9/1/2008  8/31/2010 
Jin Xu  Shanghai University of Traditional Chinese Medicine  12/9/2009  6/9/2010 
Xiang Xu  Pennsylvania State University  1/13/2010  6/13/2010 
Xiaofeng Yang  University of South Carolina  4/11/2010  4/17/2010 
Tsuyoshi Yoneda  University of Minnesota  9/4/2009  8/31/2010 
William Roy Young  Scripps Research Institute  4/10/2010  4/16/2010 
Lynn Zechiedrich  Baylor College of Medicine  4/9/2010  4/9/2010 
Zhifei Zhang  Beijing (Peking) University  2/15/2010  5/15/2010 
Weigang Zhong  University of Minnesota  9/8/2008  8/31/2010 
Laura K. Zirbel  University of California, Santa Barbara  4/9/2010  4/12/2010 