University of Electro-Communications

About: University of Electro-Communications is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Laser & Robot. The organization has 8041 authors who have published 16950 publications receiving 235832 citations. The organization is also known as: UEC & Denki-Tsūshin Daigaku.

The Worst-Case Time Complexity for Generating All Maximal Cliques

Abstract: We present a depth-first search algorithm for generating all maximal cliques of an undirected graph, in which pruning methods are employed as in Bron and Kerbosch’s algorithm. All maximal cliques generated are output in a tree-like form. Then we prove that its worst-case time complexity is O(3 n/3) for an n-vertex graph. This is optimal as a function of n, since there exist up to 3 n/3 cliques in an n-vertex graph.

On a commutative class of search directions for linear programming over symmetric cones

Abstract: The commutative class of search directions for semidefinite programming was first proposed by Monteiro and Zhang (Ref. 1). In this paper, we investigate the corresponding class of search directions for linear programming over symmetric cones, which is a class of convex optimization problems including linear programming, second-order cone programming, and semidefinite progrmming as special cases. Complexity results are established for short-step, semilong-step, and long-step algorithms. Then, we propose a subclass of the commutative class for which we can prove polynomial complexities of the interior-point method using semilong steps and long steps. This subclass still contains the Nesterov-Todd direction and the Helmberg-Rendl-Vanderbei-Wolkowicz/Kojima-Shindoh-Hara/Monteiro direction. An explicit formula to calculate any member of the class is also given.

Development of a multiplex stimulated Raman microscope for spectral imaging through multi-channel lock-in detection.

Abstract: We report the development of a multiplex stimulated Raman microscope for spectral imaging through multi-channel lock-in detection with a single light source. A white pump beam is prepared with a piece of photonic crystal fiber (PCF). The system does not require the synchronization of plural light sources or the scanning of their wavelengths, and thus a jitter-free pair of pump and Stokes beams is obtained, and a high degree of temporal synchronization is attained in the spectra. The multi-channel lock-in detection (extended to 128 channels) enables the observation of pseudo-continuous stimulated Raman spectra, demonstrating the strong ability of qualitative analysis to identify various types of C–H stretching modes such as the symmetric and asymmetric modes of the methylene/methyl and aromatic groups. Images of a mixed film of polystyrene and polymethylmethacrylate are presented to demonstrate the system's spectral imaging ability. The spatial distribution of these materials is successfully captured through one-time imaging, although the noise of the white light pump beam generated with the PCF limits the system's imaging speed.

Simultaneous fluorescence yield and lifetime tomography from time-resolved transmittances of small-animal-sized phantom

Abstract: There has been recently a considerable interest in simultaneously reconstructing yield and lifetime distributions of fluorescent imaging agents inside a bulky tissue, since combined monitoring of these two parameters provides a potential means of in vivo interrogating quantitative and environmental information of specific molecules, as well as accessing interactions among them. It is widely accepted that an advantageous way of accomplishing the task in the context of small-animal imaging is to use a time-domain (TD) modality. In this paper, we present a full three-dimensional, featured-data algorithm for TD diffuse fluorescence tomography, which inverts the Laplace-transformed TD coupled photon diffusion equations and employs a pair of real-domain transform-factors to effectively separate the fluorescent yield and lifetime parameters. By use of a specifically designed 16x16 channel time-correlated single photon counting system and a normalized Born formulation for the inversion, the proposed scheme in a transmission mode is experimentally validated to achieve simultaneous reconstruction of the fluorescent yield and lifetime distributions with reasonable accuracy.