Moscow State University

About: Moscow State University is a education organization based out in Moscow, Russia. It is known for research contribution in the topics: Laser & Population. The organization has 66747 authors who have published 123358 publications receiving 1753995 citations. The organization is also known as: MSU & Lomonosov Moscow State University.

On Detection of Multiple Object Instances Using Hough Transforms

Abstract: Hough transform-based methods for detecting multiple objects use nonmaxima suppression or mode seeking to locate and distinguish peaks in Hough images. Such postprocessing requires the tuning of many parameters and is often fragile, especially when objects are located spatially close to each other. In this paper, we develop a new probabilistic framework for object detection which is related to the Hough transform. It shares the simplicity and wide applicability of the Hough transform but, at the same time, bypasses the problem of multiple peak identification in Hough images and permits detection of multiple objects without invoking nonmaximum suppression heuristics. Our experiments demonstrate that this method results in a significant improvement in detection accuracy both for the classical task of straight line detection and for a more modern category-level (pedestrian) detection problem.

Parabolic problems for the Anderson model. I. Intermittency and related topics

Abstract: The objective of this paper is a mathematically rigorous investigation of intermittency and related questions intensively studied in different areas of physics, in particular in hydrodynamics. On a qualitative level, intermittent random fields are distinguished by the appearance of sparsely distributed sharp “peaks” which give the main contribution to the formation of the statistical moments. The paper deals with the Cauchy problem (∂/∂t)u(t,x)=Hu(t, x), u(0,x)=t 0(x) ≥ 0, (t, x) ∈ ℝ+ × ℤ d , for the Anderson HamiltonianH = κΔ + ξ(·), ξ(x),x ∈ ℤd where is a (generally unbounded) spatially homogeneous random potential. This first part is devoted to some basic problems. Using percolation arguments, a complete answer to the question of existence and uniqueness for the Cauchy problem in the class of all nonnegative solutions is given in the case of i.i.d. random variables. Necessary and sufficient conditions for intermittency of the fieldsu(t,·) ast→∞ are found in spectral terms ofH. Rough asymptotic formulas for the statistical moments and the almost sure behavior ofu(t,x) ast→∞ are also derived.

Structure, stability, and cluster-cage interactions in nitride clusterfullerenes M3N@C2n (M = Sc, Y; 2n = 68-98) : A density functional theory study

Abstract: Extensive semiempirical calculations of the hexaanions of IPR (isolated pentagon rule) and non-IPR isomers of C68−C88 and IPR isomers of C90−C98 followed by DFT calculations of the lowest energy structures were performed to find the carbon cages that can provide the most stable isomers of M3N@C2n clusterfullerenes (M = Sc, Y) with Y as a model for rare earth ions. DFT calculations of isomers of M3N@C2n (M = Sc, Y; 2n = 68−98) based on the most stable C2n6- cages were also performed. The lowest energy isomers found by this methodology for Sc3N@C68, Sc3N@C78, Sc3N@C80, Y3N@C78, Y3N@C80, Y3N@C84, Y3N@C86, and Y3N@C88 are those that have been shown to exist by single-crystal X-ray studies as Sc3N@C2n (2n = 68, 78, 80), Dy3N@C80, and Tb3N@C2n (2n = 80, 84, 86, 88) clusterfullerenes. Reassignment of the carbon cage of Sc2@C76 to the non-IPR Cs: 17490 isomer is also proposed. The stability of nitride clusterfullerenes was found to correlate well with the stability of the empty 6-fold charged cages. However, the...

Nonlinear light generation in topological nanostructures

Abstract: Topological photonics has emerged as a route to robust optical circuitry protected against disorder1,2 and now includes demonstrations such as topologically protected lasing3-5 and single-photon transport6. Recently, nonlinear optical topological structures have attracted special theoretical interest7-11, as they enable tuning of topological properties by a change in the light intensity7,12 and can break optical reciprocity13-15 to realize full topological protection. However, so far, non-reciprocal topological states have only been realized using magneto-optical materials and macroscopic set-ups with external magnets4,16, which is not feasible for nanoscale integration. Here we report the observation of a third-harmonic signal from a topologically non-trivial zigzag array of dielectric nanoparticles and the demonstration of strong enhancement of the nonlinear photon generation at the edge states of the array. The signal enhancement is due to the interaction between the Mie resonances of silicon nanoparticles and the topological localization of the electric field at the edges. The system is also robust against various perturbations and structural defects. Moreover, we show that the interplay between topology, bi-anisotropy and nonlinearity makes parametric photon generation tunable and non-reciprocal. Our study brings nonlinear topological photonics concepts to the realm of nanoscience.