BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Mina Teicher (Department of Mathematics and Gonda Brain Research C enter\, Bar-Ilan University\, Israel) DTSTART:20201210T081500Z DTEND:20201210T090500Z DTSTAMP:20260404T095326Z UID:WMSEE/1 DESCRIPTION:Title: Mathematics for analyzing brain activity\nby Mina Teicher (Depart ment of Mathematics and Gonda Brain Research Center\, Bar-Ilan University\ , Israel) as part of Women in Mathematics in South-Eastern Europe\n\n\nAbs tract\nStudying the brain and analyzing brain activity is on the forefront of science today. It is connected to Robotics\, Artificial intelligence\, brain disorders\, artificial organs and more. For the last decades\, brai n scientists believed that the main model to which the brain is subject to is firing rate and did not believe in synchronization. In this talk we wi ll describe a research project that sheds light on the theoretical questio n how does the brain work\, and in particular proves synchronization in br ain activity of behaving animals. Moreover\, we shall mention briefly few projects in clinical medicine of the brain – epilepsy and sleep disorder s.\n LOCATION:https://stable.researchseminars.org/talk/WMSEE/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Sofia Lambropoulou (School of Applied Mathematical and Physical Sc iences\, National Technical University of Athens\, Greece) DTSTART:20201210T093000Z DTEND:20201210T102000Z DTSTAMP:20260404T095326Z UID:WMSEE/2 DESCRIPTION:Title: On Knotoids and Applications\nby Sofia Lambropoulou (School of Ap plied Mathematical and Physical Sciences\, National Technical University o f Athens\, Greece) as part of Women in Mathematics in South-Eastern Europe \n\n\nAbstract\nAbstract: The theory of knotoids\, introduced by Turaev in 2011\, extends classical knot theory. In this talk we review some aspects of the theory of knotoids and present some recent developments with a foc us on singular knotoids. We also discuss applications in the topological s tudy of proteins.\n LOCATION:https://stable.researchseminars.org/talk/WMSEE/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Natasa Krejic (Faculty of Science\, University of Novi Sad\, Serbi a) DTSTART:20201210T120000Z DTEND:20201210T125000Z DTSTAMP:20260404T095326Z UID:WMSEE/3 DESCRIPTION:Title: Inexact Restoration Methods for Finite Sum Minimization\nby Natas a Krejic (Faculty of Science\, University of Novi Sad\, Serbia) as part of Women in Mathematics in South-Eastern Europe\n\n\nAbstract\nConvex and no nconvex finite-sum minimization arises in many scientific computing and ma chine learning applications. Recently\, first-order and second-order metho ds where objective functions\, gradients and Hessians are approximated by randomly sampling components of the sum have received great attention. We discuss a class of methods which employs suitable approximations of the ob jective function\, gradient and Hessian built via random subsampling techn iques. The choice of the sample size is deterministic and ruled by the Ine xact Restoration approach. Local and global properties for finding approxi mate first- and second-order optimal points and function evaluation comple xity results are discussed in the framework of line search and trust regio n methods.\n LOCATION:https://stable.researchseminars.org/talk/WMSEE/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Nadezhda Ribarska (Faculty of Mathematics and Informatics\, Sofia University “St. Kliment Ohridski”\, Bulgaria) DTSTART:20201210T132000Z DTEND:20201210T141000Z DTSTAMP:20260404T095326Z UID:WMSEE/4 DESCRIPTION:Title: On a non-smooth problem of the calculus of variations\nby Nadezhd a Ribarska (Faculty of Mathematics and Informatics\, Sofia University “S t. Kliment Ohridski”\, Bulgaria) as part of Women in Mathematics in Sout h-Eastern Europe\n\n\nAbstract\nThe specificity of the basic problem of th e calculus of variations considered as a constraint optimization problem o n an infinite-dimensional space is discussed. A sufficient condition for t angential transversality involving measures of non-compactness as well as a Lagrange multiplier theorem for the infinite-dimensional optimization pr oblem are obtained. The relation of the obtained results to the basic prob lem of calculus of variations is discussed.\n\nThe talk is based on a join t work with Mikhail Krastanov.\n LOCATION:https://stable.researchseminars.org/talk/WMSEE/4/ END:VEVENT BEGIN:VEVENT SUMMARY:Ana Irina Nistor (Department of Mathematics and Informatics “Gh. Asachi” Technical University of Iasi\, Romania) DTSTART:20201211T080000Z DTEND:20201211T085000Z DTSTAMP:20260404T095326Z UID:WMSEE/5 DESCRIPTION:Title: Magnetic trajectories on almost contact metric manifolds\nby Ana Irina Nistor (Department of Mathematics and Informatics “Gh. Asachi” T echnical University of Iasi\, Romania) as part of Women in Mathematics in South-Eastern Europe\n\n\nAbstract\nThis presentation consists in a collec tion of results obtained so far in the study of magnetic trajectories as w ell as some future work. As the study of magnetic trajectories was intensi vely developed in Kaehler manifolds\, where the Kaehler 2-form is closed a nd hence defines a magnetic field\, we investigate the magnetic curves in quasi-Sasakian manifolds. In\nparticular\, the magnetic curves in Sasakian and cosymplectic manifolds of arbitrary dimension are classified. The 3-d imensional case is quite important\, as it is well known that the geometry of quasi-Sasakian 3-manifolds is rather special and we will present the r esults obtained in the study of magnetic trajectories.\n LOCATION:https://stable.researchseminars.org/talk/WMSEE/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Betul Bulca (Department of Mathematics\, Uludağ University\, Burs a\, Turkey) DTSTART:20201211T093000Z DTEND:20201211T102000Z DTSTAMP:20260404T095326Z UID:WMSEE/6 DESCRIPTION:Title: The theory and the geometric modelling of curves and surfaces in Eucl idean spaces\nby Betul Bulca (Department of Mathematics\, Uludağ Univ ersity\, Bursa\, Turkey) as part of Women in Mathematics in South-Eastern Europe\n\n\nAbstract\nIn this talk we give the theory of the curves and su rfaces in Euclidean spaces. We give some basic concepts of the surfaces es pecially in Euclidean four space. In this study\, the well- known geometri c modeling and interpolation methods for curves and surfaces will be empha sized and also the studies in this area will be mentioned. Some well-known surfaces (such as rotational surface family) will be discussed and exampl es of these surfaces will be given. Also we present our recent works on th e geometric modelling of the biological plants. Further\, we discuss the B ezier interpolation methods with curves in Euclidean 4-space.\n LOCATION:https://stable.researchseminars.org/talk/WMSEE/6/ END:VEVENT BEGIN:VEVENT SUMMARY:Velichka Milousheva (Institute of Mathematics and Informatics\, Bu lgarian Academy of Sciences\, Bulgaria) DTSTART:20201211T120000Z DTEND:20201211T125000Z DTSTAMP:20260404T095326Z UID:WMSEE/7 DESCRIPTION:Title: Marginally trapped (quasi-minimal) surfaces in pseudo-Euclidean 4-spa ces\nby Velichka Milousheva (Institute of Mathematics and Informatics\ , Bulgarian Academy of Sciences\, Bulgaria) as part of Women in Mathematic s in South-Eastern Europe\n\n\nAbstract\nA surface in a pseudo-Riemannian manifold is called quasi-minimal if its mean curvature vector is lightlike at each point of the surface. When the ambient space is the Lorentz-Minko wski space\, the quasi-minimal submanifolds are also called marginally tra pped – a notion borrowed from General Relativity. The concept of trapped surfaces was first introduced by Sir Roger Penrose in 1965 in connection with the theory of cosmic black holes.\n\nMarginally trapped surfaces in s pacetimes satisfying some extra conditions have recently been\nintensively studied in connection with the rapid development of the theory of black h oles in Physics. Most of the results give a complete classification of mar ginally trapped surfaces under some additional geometric conditions\, such as having positive relative nullity\, having parallel mean curvature vect or field\, having pointwise 1-type Gauss map\, being invariant under space like rotations\, under boost transformations\, or under the group of screw rotations.\n\nQuasi-minimal surfaces in the pseudo-Euclidean 4-space with neutral metric satisfying some additional conditions have also been studi ed actively in the last few years. Most of the results are due to Bang-Yen Chen and his collaborators.\n\nIn this talk we will give an overview of t hese classification results and present the Fundamental existence and uniq ueness theorem for the general class of quasi-minimal Lorentz surfaces in the pseudo-Euclidean 4-space with neutral metric.\n LOCATION:https://stable.researchseminars.org/talk/WMSEE/7/ END:VEVENT BEGIN:VEVENT SUMMARY:Sanja Atanasova (Faculty of Electrical Engineering and Information Technologies\, “Ss. Cyril and Methodius” University in Skopje\, North Macedonia) DTSTART:20201211T132000Z DTEND:20201211T141000Z DTSTAMP:20260404T095326Z UID:WMSEE/8 DESCRIPTION:Title: Integral transforms through the prism of distribution theory\nby Sanja Atanasova (Faculty of Electrical Engineering and Information Technol ogies\, “Ss. Cyril and Methodius” University in Skopje\, North Macedon ia) as part of Women in Mathematics in South-Eastern Europe\n\n\nAbstract\ nThe Fourier transform is probably the most widely applied signal processi ng tool in science and engineering. It reveals the frequency composition o f a time series by transforming it from the time domain into the frequency domain. However\, it does not reveal how the signals frequency contents v ary with time. A straightforward solution to overcoming the limitations of the Fourier transform the concept of the short-time Fourier transform (ST FT). The short-time Fourier transform is a very effective device in the st udy of function spaces. However\, significant barrier in application of th e STFT is the fact that the fixed window function has to be predefined\, w hich leads to a poor time-frequency resolution and\, in general\, the abse nce of a sufficiently good reconstruction algorithm. The Wavelet transform (WT) is used to overcome some of the shortcomings of the STFT. With the d ilatation and translation of the window function\, the WT has better phase modulation in the spectral domain. However\, the self-similarity caused b y the translation and the overlap in the frequency domain becomes non-avoi dable since they do not permit straightforwardly the transfer of scale inf ormation into proper frequency information. The Stockwell transform (ST) a lso decomposes a signal into temporal and frequency components. In contras t to the WT\, the ST exhibits a frequency-invariant amplitude response and covers the whole temporal axis creating full resolutions for each designa ted frequency. It is invertible\, and recovers the exact phase and the fre quency information without reconstructing the signal. The problem with the ST is its redundancy. But\, there have been different strategies in order to improve the performance and the application of the ST.\n\nOn the other hand\, the STFT\, as a tool of the time-frequency analysis\, contains loc alized time and frequency information of a function. Another idea is to lo calize information in time\, frequency\, and direction\, which leads to di rectionally sensitive variant of STFT\, which gives the Directional short time Fourier transform (DSTFT).\n\nIn mathematics\, distributions extend t he notion of functions. Distribution theory is a power tool in applied mat hematics and the extension of integral transforms to generalized function spaces is an important subject with a long tradition. The theory is develo ped by proving that these transforms are well defined on the appropriate s paces of distribution. These is done by proving continuity results for the se transforms on so called test function spaces\, and then extending the d efinitions on distributions. In this talk\, i consider several integrals t ransforms (STFT\, WT\, ST\, DSTFT) and try to make short survey on their b ehaviour on distributions.\n\nThere are several approaches to the the ory of distributions\, but in all of them one quickly learn that distributions do not have point values\, as functions do\, despite the fa ct that they are called generalized functions. Natural generalization of this notion is the quasiasymptotic behavior of distributions. It is an old subject that has found applications in various fields of pure a nd applied mathematics\, physics\, and engineering. In the second par t of my talk\, I use Abelian and Tauberian ideas for asymptotic analysis of the mentioned integral transforms to characterize the asymptotic proper ties of a distribution.\n LOCATION:https://stable.researchseminars.org/talk/WMSEE/8/ END:VEVENT END:VCALENDAR