Holon Institute of Technology Dear Colleagues, Our next Colloquium in Mathematics and Computer Science will take place on Tuesday, February 26, at 12:00. Speaker: Prof. Mark Agranovsky Affiliation: Bar-Ilan University, Ramat Gan, Israel Title: Spherical Waves, Nodal Sets and Thermoacoustic Tomography Date: Tuesday, February 26, 2013 Time: 12:00 Venue: Room 424/8, Science Building Abstract: Can one reconstruct a function from knowing the integrals over all spheres with centers on a given surface? That integral-geometric problem is closely related to the following interrelated questions: 1) what are complete systems of shifted radial functions (spherical waves)? 2) what are joint zero (nodal) sets of large families of eigenfunctions of the Laplace operator? 3) how to reconstruct the initial value (and hence the solution) of the wave equation in the whole space from observing, for all values of time, the restriction of the solution on a hypersurface? The latter question is a mathematical formulation of the reconstruction problem in the photo- and thermoacoustic tomography, which is a type of hybrid tomography - a new trend in medical imaging. In my talk, I will give a survey of what we know by today and what we do not know on the above questions. Light refreshments will be served at 11:45 am. Everybody is welcome. Looking forward to seeing you all, Anatoly Golberg, Dmitry Goldstein, Eugen Mandrescu Holon Institute of Technology, 52 Golomb St, Holon, 03-5026560, http://www.hit.ac.il/acc/golberga/Events/Colloquia.html --------------------------------------------------------- Technion Math Net-2 (TECHMATH2) Editor: Michael Cwikel <techm@math.technion.ac.il> Announcement from: Anatoly Golberg <golberga@hit.ac.il>