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Nicola Visciglia (U.Pisa)  WPI, OMP 1, Seminar Room 08.135  Tue, 20. Sep 16, 0:00 
"Existence and Stability of Standing Waves for NLS in a partial confinement"  
I will discuss a joint work with Bellazzini, Boussaid, Jeanjean about the existence and orbital stability of standing waves for NLS with a partial confinement in a supercritical regime. The main point is to show the existence of local minimizers of the constraint energy.  

Vincent Duchêne (U. Rennes I)  WPI, OMP 1, Seminar Room 08.135  Tue, 20. Sep 16, 0:00 
"On the wellposedness of the GreenNaghdi System"  
The GreenNaghdi system is an asymptotic model for the waterwaves system, describing the propagation of surface waves above a layer of ideal, homogeneous, incompressible and irrotational fluid, when the depth of the layer is assumed to be small with respect to wavelength of the flow. It can be seen as a perturbation of the standard quasilinear (dispersionless) SaintVenant system, with additional nonlinear higherorder terms. Because of the latter, the wellposedness theory concerning the GN system is not satisfactory, in particular outside of the onedimensional framework. We will discuss novel results, obtained with Samer Israwi, that emphasize the role of the irrotationality assumption.  

Thomas Kappeler (U. Zürich)  WPI, OMP 1, Seminar Room 08.135  Tue, 20. Sep 16, 0:00 
"Analytic extensions of frequencies of integrable PDEs and applications"  
In form of a case study for the mKdV and the KdV2 equation we discuss a novel approach of representing frequencies of integrable PDEs which allows to extend them analytically to spaces of low regularity and to study their asymptotics. Applications include wellposedness results in spaces of low regularity as well as properties of the actions to frequencies map. This is joint work with Jan Molnar.  

Hajer Bahouri (UPEC)  WPI, OMP 1, Seminar Room 08.135  Tue, 20. Sep 16, 0:00 
"Qualitative study of 2D Schrodinger equation with exponential nonlinearity"  
In this lecture, we investigate the behavior of the solutions to the nonlinear Schrodinger equation: (1) ( i@tu + u = f(u); ujt=0 = u0 2 H1 rad(R2); where the nonlinearity f : C ! C is dened by (2) f(u) = p( p 4 juj) u with p > 1 and p(s) = es2 pX1 k=0 s2k k! Recall that the solutions of the Cauchy problem (1)(2) formally satisfy the conservation laws: (3) M(u; t) = Z R2 ju(t; x)j2dx = M(u0) and (4) H(u; t) = Z R2 jru(t; x)j2 + Fp(u(t; x)) dx = H(u0) ; where Fp(u) = 1 4 p+1 p 4 juj It is known (see [4], [6] and [2]) that global wellposedness for the Cauchy problem (1)(2) holds in both subcritical and critical regimes in the functional space C(R;H1(R2)) \ L4(R;W1;4(R2)). Here the notion of criticity is related to the size of the initial Hamiltonian H(u0) with respect to 1. More precisely, the concerned Cauchy problem is said to be subcritical if H(u0) < 1, critical if H(u0) = 1 and supercritical if H(u0) > 1. Structures theorems originates in the elliptic framework in the studies by H. Brezis and J. M. Coron in [3] and M. Struwe in [8]. The approach that we shall adopt in this article consists in comparing the evolution of oscillations and concentration eects displayed by sequences of solutions of the nonlinear Schrodinger equation (1)(2) and solutions of the linear Schrodinger equation associated to the same sequence of Cauchy data. Our source of inspiration here is the pioneering works [1] and [7] whose aims were to describe the structure of bounded sequences of solutions to semilinear defocusing wave and Schrodinger equations, up to small remainder terms in Strichartz norms. The analysis we conducted in this work emphasizes that the nonlinear eect in this framework only stems from the 1oscillating component of the sequence of the Cauchy data, using the terminology introduced in [5]. This phenomenon is strikingly dierent from those obtained for critical semi linear dispersive equations, such as for instance in [1, 7] where all the oscillating components induce the same nonlinear eect, up to a change of scale. To carry out our analysis, we have been led to develop a prole decomposition of bounded sequences of solutions to the linear Schrodinger equation both in the framework of Strichartz and Orlicz norms. The linear structure theorem we have obtained in this work highlights the distinguished role of the 1oscillating component of the sequence of the Cauchy data. It turns out that there is a form of orthogonality between the Orlicz and the Strichartz norms for the evolution under the ow of the free Schrodinger equation of the unrelated component to the scale 1 of the Cauchy data (according to the vocabulary of [5]), while this is not the case for the 1oscillating component.  

Eric Wahlen (NTNU)  WPI, OMP 1, Seminar Room 08.135  Tue, 20. Sep 16, 0:00 
"On the highest wave for Whitham’s wave equation"  
In the 1960’s G. B. Whitham suggested a nonlocal version of the KdV equation as a model for water waves. Unlike the KdV equation it is not integrable, but it has certain other advantages. In particular, it has the same dispersion relation as the full water wave problem and it allows for wave breaking. The equation has a family of periodic, travelling wave solutions for any given wavelength. Whitham conjectured that this family contains a highest wave which has a cusp at the crest. I will outline a proof of this conjecture using global bifurcation theory and precise information about an integral operator which appears in the equation. Joint work with M. Ehrnström.  

Mats Ehrnström (NTNU)  WPI, OMP 1, Seminar Room 08.135  Tue, 20. Sep 16, 0:00 
"Existence of a Highest Wave in a FullDispersion Shallow Water Model"  
We consider the existence of periodic traveling waves in a bidirectional Whitham equation, combining the full twoway dispersion relation from the incompressible Euler equations with a canonical quadratic shallow water nonlinearity. Of particular interest is the existence of a highest, cusped, traveling wave solution, which we obtain as a limiting case at the end of the main bifurcation branch of $2pi$periodic traveling wave solutions. Unlike the unidirectional Whitham equation, containing only one branch of the full Euler dispersion relation, where such a highest wave behaves like $x^{1/2}$ near its peak, the cusped waves obtained here behave like $xlogx$ at their peak and are smooth away from their highest points. This is joint work with Mathew A. Johnson and Kyle M. Claassen at University of Kansas.  

Oana Ivanovici (U. Nizza)  WPI, OMP 1, Seminar Room 08.135  Tue, 20. Sep 16, 0:00 
"Dispersion for the wave and the Schrödinger Equations outside strictly convex Domains and counterexamples"  
We consider the linear wave equation and the linear Schr dingier equation outside a compact, strictly convex obstacle in R^d with smooth boundary. In dimension d = 3 we show that for both equations, the linear flow satises the (corresponding) dispersive estimates as in R^3. For d>3, if the obstacle is a ball, we show that there exists at least one point (the Poisson spot) where the dispersive estimates fail. This is joint work with Gilles Lebeau.  

Evelyne Miot (U. Grenoble Alpes)  WPI, OMP 1, Seminar Room 08.135  Tue, 20. Sep 16, 0:00 
"Collision of vortex Filaments"  
In this talk we will present some results on the dynamics of vortex filaments according to a model introduced by Klein, Majda and Damodaran, focusing on the issue of collisions. This is a joint work with Valeria Banica and Erwan Faou.  

Mauser, Norbert (Inst. CNRS Pauli c/o Fak. Mathematik U. Wien)  OMP 1, Fakultät für Mathematik, 1090 Wien  Wed, 21. Sep 16, 19:00 
Austro  Französische Mathematik: ein Diskurs  
Warum ist Frankreich das weltweit führende Land in Mathematik ? Warum gibt es in Frankreich eine Sektion 25 und eine Sektion 26  und in Österreich eine Sektion Forschung und eine Sektion Universitäten ?! Warum gibt es 2 französische FieldsMedaillen zur Boltzmanngleichung ? Warum ist eines der nur 3 europäischen CNRS Institute « extra muros » am WPI in Wien ? Warum kommen viele österreichische Spitzenmathematiker vom Lycée français de Vienne ? Diese und andere interessante Fragen wird uns Herr Prof. Mauser in seinem Vortrag (in deutscher Sprache) beantworten.  
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BenavidesRiveros, Carlos (U.HalleWittenberg)  WPI, OMP1, Seminar Room 08.135  Fri, 12. Aug 16, 15:15 
“Natural extension of HartreeFock through extremal 1fermion Information”  
By employing the simpler structure arising from pinning and quasipinnig a variational optimization method for few fermion ground states is elaborated. We quantitatively confirm its high accuracy for systems whose vector of NON is close to the boundary of the polytope. In particular, we derive an upper bound on the error of the correlation energy given by the ratio of the distance to the boundary of the polytope and the distance of the vector of NON to the HartreeFock point. These geometric insights shed some light on the concept of active spaces, correlation energy, frozen electrons and virtual orbitals.  

Schilling, Christian (U. Oxford)  WPI, OMP1, Seminar Room 08.135  Fri, 12. Aug 16, 14:00 
“Fermionic exchange symmetry: quantifying its influence beyond Pauli's Exclusion Principle"  
The Pauli exclusion principle has a strong impact on the properties and the behavior of most fermionic quantum systems. Remarkably, even stronger restrictions on fermionic natural occupation numbers follow from the fermionic exchange symmetry. We develop an operationally meaningful measure which allows one to quantify the potential physical relevance of those generalized Pauli constraints beyond the wellestablished relevance of Pauli's exclusion principle. It is based on a geometric hierarchy induced by Pauli exclusion principle constraints. The significance of that measure is illustrated for a fewfermion model which also confirms such nontrivial relevance of the generalized Pauli constraints.  

Brezinova, Iva (TU. Wien)  WPI, OMP1, Seminar Room 08.135  Fri, 12. Aug 16, 11:00 
“Solving timedependent manybody quantum problems using the twoparticle reduced density matrix”  
In this talk we will give an overview over our recent progress in solving timedependent manybody problems using the twoparticle reduced density matrix (2RDM) as the fundamental variable. The wavefunction is completely avoided and with this all problems arising from the exponentially increasing complexity with particle number. Key is the reconstruction of the 3RDM which couples to the dynamics of the 2RDM. At this point the approximation to the full solution of the Schrödinger equation enters: while twoparticle correlations are fully incorporated, threeparticle correlations are only approximated. We will discuss the reconstruction of the 3RDM, how we overcome the Nrepresentability problem, and demonstrate the accuracy of our theory on twoexamples: multielectron atoms in strong fields, and ultracold atoms in optical lattices.  

Gottlieb, Alexander (WPI)  WPI, OMP1, Seminar Room 08.135  Fri, 12. Aug 16, 10:00 
“Quasiseparated electron pairs in small molecules”  
Some of the electrons in a molecule are tightly bound to the nuclei. The closely bound "core electrons" can be relatively uncorrelated with the rest of the electrons in the molecule, and may even form what we call a "quasiseparated" pair. [Let F be the electronic wave function of a molecule with N+2 electrons. We say that F features a "quasiseparated pair" if it is approximately equal to the wedge product G ^ H of a geminal G that describes the state of the separated pair and an Nelectron wave function H that is strongly orthogonal to G.] We have computational evidence of such quasiseparated electron pairs in the ground states of very small molecules (like LiH or the Be atom) whose correlated electronic structure can be very accurately approximated with full CI calculations.  

Gottlieb, Alexander (WPI)  WPI, OMP1, Seminar Room 08.135  Thu, 11. Aug 16, 16:00 
“Geometry of the BorlandDennis setting: the Wtype class”  
We call the Hilbert space for three fermions in six orbitals the BorlandDennis setting. It is isomorphic to the alternating tensor product of three copies of the standard 6dimensional Hilbert space C^6. Slater determinant states in the BorlandDennis setting correspond to "decomposable" trivectors, i.e., simple wedge products of three vectors from C^6. Generic wave functions in the BorlandDennis setting can be written as a sum of just two decomposable trivectors. The wave functions that cannot be written as a sum of fewer than three decomposables constitute the "Wtype entanglement class." I will discuss the geometry of the Wtype class within the ambient BorlandDennis space.  

BenavidesRiveros, Carlos (U.HalleWittenberg)  WPI, OMP1, Seminar Room 08.135  Thu, 11. Aug 16, 14:30 
“Pinning and quasipinning in quantum chemistry”  
It is now known that fermionic natural occupation numbers (NONs) do not only obey Pauli’s exclusion principle but are even stronger restricted by the socalled generalized Pauli constraints (GPC). Whenever given NONs lie on or close to the boundary of the allowed region the corresponding Nfermion quantum state has a significantly simpler structure. We explore this phenomenon in the context of quantum chemistry.  

Schilling, Christian (U. Oxford)  WPI, OMP1, Seminar Room 08.135  Thu, 11. Aug 16, 13:30 
“Quantum marginal problem and generalized Pauli constraints”  
The question whether given reduced density operators (marginals) for subsystems of a multipartite quantum system are compatible to a common total state is called quantum marginal problem (QMP). We present the solution found by A. Klyachko just a few years ago as well as the main steps for its derivation. Applying those concepts to fermionic systems reveals further constraints on fermionic occupation numbers beyond Pauli's famous exclusion principle. We introduce and discuss these socalled generalized Pauli constraints in great detail and comment on their potential physical relevance.  

Komarov, Sergey (MPA & U. Princeton)  WPI Seminar Room 08.135  Fri, 5. Aug 16, 10:00 
CR Diffusion  "Cosmic ray Diffusion in mirror fluctuations"  
TBA  

Rincon, Francois (U. Toulouse)  WPI Seminar Room 08.135  Fri, 5. Aug 16, 10:00 
Convection  "Turbulent convection theories for the Sun"  
TBA  

Stone, Jim (U. Princeton)  WPI Seminar Room 08.135  Thu, 4. Aug 16, 17:00 
MRI/Turbulence  "Reconnection in shearing box simulations of the MRI"  
TBA  

Schekochikin, Alex (U. Oxford)  WPI Seminar Room 08.135  Thu, 4. Aug 16, 16:00 
Phase Mixing  "Phasespace turbulence in 2, 4 and 5D"  
TBA  

Lesur, Geoffroy (U. Grenbole)  WPI Seminar Room 08.135  Thu, 4. Aug 16, 10:00 
MHD  "Vortex stability in nonideal MHD"  
TBA  

Loureiro, Nuno (MIT)  WPI Seminar Room 08.135  Wed, 3. Aug 16, 16:45 
"The onset of magnetic reconnection"  
TBA  

Sironi, Lorenzo (U. Harvard & U. Columbia)  WPI Seminar Room 08.135  Wed, 3. Aug 16, 16:00 
Reconnection  "Magnetic reconnection in relativistic astrophysical jets"  
TBA  

Spirkovsky, Anatoly (U. Princeton)  WPI Seminar Room 08.135  Wed, 3. Aug 16, 10:30 
CR Instabilities  "Kinetics of cosmic raydriven instabilities and winds"  
TBA  

Bethune, William (U. Grenoble)  WPI Seminar Room 08.135  Wed, 3. Aug 16, 10:00 
MRI  "Nonideal MRI in protoplanetary disks"  
TBA  

Cowley, Steve (UKAEA & U. Oxford)  WPI Seminar Room 08.135  Tue, 2. Aug 16, 16:30 
Transport & Stability  "Stability of the ChapmanEnskog solution in weakly collisional Plasma"  
TBA  

RobergClark, Gareth (U. Maryland)  WPI Seminar Room 08.135  Tue, 2. Aug 16, 16:00 
Transport & Stability  "Suppression of electron thermal conduction in highbeta plasma"  
TBA  

Medvedev, Michael (U. Kansas)  WPI Seminar Room 08.135  Tue, 2. Aug 16, 11:00 
Transport  "Thermal conductivity and effective collisionality of astrophysical plasmas"  
TBA  

Bott, Archie (U. Oxford)  WPI Seminar Room 08.135  Tue, 2. Aug 16, 10:00 
Plasama Dynamo  "Dynamo on Omega laser and kinetic Problems of Proton radiography"  
TBA  

Kunz, Matt (U.Princeton)  WPI Seminar Room 08.135  Mon, 1. Aug 16, 16:30 
MRI/Turbulence  "Kinetic MRI turbulence" & "Kinetic solarwind turbulence"  
TBA  

StOnge, Denis (U. Princeton)  WPI Seminar Room 08.135  Mon, 1. Aug 16, 16:00 
Plasma Dynamo  "Hybrid PIC simluations of plasma dynamo"  
TBA  

Strumik, Marek (U. Oxford)  WPI Seminar Room 08.135  Mon, 1. Aug 16, 11:00 
HighBeta  CGL Dynamics and beta Limits on fluctuations in the solar wind"  
TBA  

Squire, Jonathan (Caltech)  WPI Seminar Room 08.135  Mon, 1. Aug 16, 10:30 
HighBeta  "Amplitude limits on alfvenic perturbations in weakly magnetized lowcollisionality plasmas"  
TBA  

Ball, Justin (U. Oxford & EPFL)  WPI Seminar Room 08.135  Fri, 29. Jul 16, 10:00 
UpDown Asymmetry  "Updown asymmetric tokamaks"  
TBA  

Abel, Ian (U. Princeton & U. Greifswald)  WPI Seminar Room 08.135  Thu, 28. Jul 16, 16:00 
Turbulence & Transport  "Sensitivitiy (to input parameters) calculation in gyrokinetics"  
TBA  

Schekochihin, Alexander (U. Oxford)  WPI Seminar Room 08.135  Thu, 28. Jul 16, 10:00 
Turbulence & Transport  "Some updates on ion and electronscale turbulence in MAST"  
TBA  

St. Onge, Denis (U. Princeton)  WPI Seminar Room 08.135  Wed, 27. Jul 16, 16:00 
Turbulence & Transport  "Dimits shift in one and twofield models"  
TBA  

Citrin, Jonathan (CEA)  WPI Seminar Room 08.135  Wed, 27. Jul 16, 11:00 
Turbulence & Transport  "Comparision between measured and predicted turbulence frequency spectra in ITG and TEM regimes"  
TBA  

Calvo, Ivan (CIEMAT)  WPI Seminar Room 08.135  Wed, 27. Jul 16, 10:00 
Stellarators  "The effect of tangential drifts on neoclassical Transport in stellarator close to omnigeneity"  
TBA  

Hammett, Greg (U. Princeton)  WPI Seminar Room 08.135  Tue, 26. Jul 16, 16:30 
SOL  "5D turbulence simluations with Gkeyll, in the presence of open field lines and sheath boundary conditions, in a torpex/helimak helical model of a SOL"  
TBA  

Geraldini, Alessandro (U. Oxford)  WPI Seminar Room 08.135  Tue, 26. Jul 16, 16:00 
SOL  "Kinetic theory of Ions in the magnetic presheath"  
TBA  

Ricci, Paolo (EPFL)  WPI Seminar Room 08.135  Tue, 26. Jul 16, 10:00 
SOL  "Physics at EPFL"  
TBA  

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