Tokyo University of Information science is a private university in Wakaba Ward of the city of Chiba, Chiba Prefecture, Japan. The university was established in 1988 by the School corporation Tokyo University of Agriculture. The university consists of four departments: Information System, Environmental Information, Business & Information, and Media & Cultural Studies. To follow the rapid period changing and better contribution for our society, we always make our best on student education of their creativity and excellent personality. Wikipedia.
Hasegawa Y.,Tokyo University of Information Sciences
New Journal of Physics | Year: 2016
Cells use temporal dynamical patterns to transmit information via signaling pathways. As optimality with respect to the environment plays a fundamental role in biological systems, organisms have evolved optimal ways to transmit information. Here, we use optimal control theory to obtain the dynamical signal patterns for the optimal transmission of information, in terms of efficiency (low energy) and reliability (low uncertainty). Adopting an activation-deactivation decoding network, we reproduce several dynamical patterns found in actual signals, such as steep, gradual, and overshooting dynamics. Notably, when minimizing the energy of the input signal, the optimal signals exhibit overshooting, which is a biphasic pattern with transient and steady phases; this pattern is prevalent in actual dynamical patterns. We also identify conditions in which these three patterns (steep, gradual, and overshooting) confer advantages. Our study shows that cellular signal transduction is governed by the principle of minimizing free energy dissipation and uncertainty; these constraints serve as selective pressures when designing dynamical signaling patterns. © 2016 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Kim B.,Tokyo University of Information Sciences |
Naemura T.,Tokyo University of Information Sciences
Scientific Reports | Year: 2015
This paper proposes a new deconvolution method for 3D fluorescence wide-field microscopy. Most previous methods are insufficient in terms of restoring a 3D cell structure, since a point spread function (PSF) is simply assumed as depth-invariant, whereas a PSF of microscopy changes significantly along the optical axis. A few methods that consider a depth-variant PSF have been proposed; however, they are impractical, since they are non-blind approaches that use a known PSF in a pre-measuring condition, whereas an imaging condition of a target image is different from that of the pre-measuring. To solve these problems, this paper proposes a blind approach to estimate depth-variant specimen-dependent PSF and restore 3D cell structure. It is shown by experiments on that the proposed method outperforms the previous ones in terms of suppressing axial blur. The proposed method is composed of the following three steps: First, a non-parametric averaged PSF is estimated by the Richardson Lucy algorithm, whose initial parameter is given by the central depth prediction from intensity analysis. Second, the estimated PSF is fitted to Gibson's parametric PSF model via optimization, and depth-variant PSFs are generated. Third, a 3D cell structure is restored by using a depth-variant version of a generalized expectation-maximization.
Gozolchiani A.,Bar - Ilan University |
Havlin S.,Bar - Ilan University |
Yamasaki K.,Tokyo University of Information Sciences
Physical Review Letters | Year: 2011
We construct and analyze a climate network which represents the interdependent structure of the climate in different geographical zones and find that the network responds in a unique way to El Niño events. Analyzing the dynamics of the climate network shows that when El Niño events begin, the El Niño basin partially loses its influence on its surroundings. After typically three months, this influence is restored while the basin loses almost all dependence on its surroundings and becomes autonomous. The formation of an autonomous basin is the missing link to understand the seemingly contradicting phenomena of the afore-noticed weakening of the interdependencies in the climate network during El Niño and the known impact of the anomalies inside the El Niño basin on the global climate system. © 2011 American Physical Society.
Yoon M.-G.,Gangneung - Wonju National University |
Tsumura K.,Tokyo University of Information Sciences
Automatica | Year: 2011
This paper presents explicit forms of transfer functions for a class of cyclic consensus systems with different kinds of network topologies; directed, undirected and different numbers of reference agents. Each agent of consensus systems is assumed to satisfy a scalar integrator dynamics which is driven by a common consensus protocol and an independent exogenous input. It is shown that every single-input single-output (SISO) transfer function between the exogenous input of one agent and the state of another generally different agent, is always minimum phase. In addition, the poles and zeros, system degrees and relative degrees of those SISO transfer functions are specified. These results are interpreted in relation to the controllability and closed loop performance of a networked system with one leader agent. Furthermore, our transfer function representations are applied to an investigation of stability margins for a closed loop cyclic consensus system. © 2011 Elsevier Ltd. All rights reserved.
Iwata Y.,Tokyo University of Information Sciences
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012
Measure and Conquer is a recently developed technique to analyze worst-case complexity of backtracking algorithms. The traditional measure and conquer analysis concentrates on one branching at once by using only small number of variables. In this paper, we extend the measure and conquer analysis and introduce a new analyzing technique named "potential method" to deal with consecutive branchings together. In potential method, the optimization problem becomes sparse; therefore, we can use large number of variables. We applied this technique to the minimum dominating set problem and obtained the current fastest algorithm that runs in O(1.4864 n ) time and polynomial space. We also combined this algorithm with a precalculation by dynamic programming and obtained O(1.4689 n ) time and space algorithm. These results show the power of the potential method and possibilities of future applications to other problems. © 2012 Springer-Verlag.
Nishimura A.,Tokyo University of Information Sciences
International Journal of Innovative Computing, Information and Control | Year: 2010
A technique for audio data hiding by using subband amplitude modulation was evaluated by computer simulations in terms of robustness with respect to the cumulative effects of reverberations, background noise, and encoding and decoding with a speech codec. Speech signals from 22 speakers and signals from 100 pieces of music were used as the host audio data. Computer simulations revealed that speech and music signals with background noise and reverberations were able to transmit at least 80% of the embedded data at 8 bps after encoding and decoding using the Adaptive Multi-Rate (AMR) speech codec at a bitrate of 12.2 kbps. In actual measurements in a reverberant room using a cell phone terminal, data hidden in a 12.2-kbps AMR recording having a signal-to-noise ratio of 20 dB was detected at a mean bit error rate of 15 %. The sound quality degradation induced by data hiding was objectively measured using the perceptual evaluation of speech quality (PESQ) and perceptual evaluation of audio quality (PEAQ) algorithms. The average PESQ score of the speech signals approximately corresponded to a subjective evaluation of 'fair', while the average PEAQ score of the music signals corresponded to a somewhat lower subjective evaluation of 'slightly annoying'. ©2010 ISSN 1349-4198.
Kobayashi N.,Tokyo University of Information Sciences
Journal of the ACM | Year: 2013
We propose a novel verification method for higher-order functional programs based on higher-order model checking, or more precisely, model checking of higher-order recursion schemes (recursion schemes, for short). The most distinguishing feature of our verification method for higher-order programs is that it is sound, complete, and automatic for the simply typed λ-calculus with recursion and finite base types, and for various program verification problems such as reachability, flow analysis, and resource usage verification. We first show that a variety of program verification problems can be reduced to model checking problems for recursion schemes, by transforming a program into a recursion scheme that generates a tree representing all the interesting possible event sequences of the program. We then develop a new type-based model-checking algorithm for recursion schemes and implement a prototype recursion scheme model checker. To our knowledge, this is the first implementation of a recursion scheme model checker. Experiments show that ourmodel checker is reasonably fast, despite the worst-case time complexity of recursion scheme model checking being hyperexponential in general. Altogether, the results provide a new, promising approach to verification of higher-order functional programs. © ACM 2013.
Hirai H.,Tokyo University of Information Sciences
Mathematical Programming | Year: 2013
In this paper, we establish a novel duality relationship between node-capacitated multiflows and tree-shaped facility locations. We prove that the maximum value of a tree-distance-weighted maximum node-capacitated multiflow problem is equal to the minimum value of the problem of locating subtrees in a tree, and the maximum is attained by a half-integral multiflow. Utilizing this duality, we show that a half-integral optimal multiflow and an optimal location can be found in strongly polynomial time. These extend previously known results in the maximum free multiflow problems. We also show that the set of tree-distance weights is the only class having bounded fractionality in maximum node-capacitated multiflow problems. © 2011 Springer and Mathematical Optimization Society.
Nishimura A.,Tokyo University of Information Sciences
Proceedings of Meetings on Acoustics | Year: 2013
Various attacks on robust audio watermarking have been proposed. Excessive intentional modifications and/or perceptual coding to the distributed stego audio degrades sound quality and can prevent the extraction of hidden data so that piracy detection systems using automated watermarking and crawling are disrupted. Reversible signal processing attacks, such as linear speed changes, also degrade the sound quality of distributed stego audio. However, the inverse processing of the reversible processing attack can recover the original sound quality of the audio received after illegal distribution. Therefore, the degradation of sound quality induced by perceptual codecs and reversible processing attacks followed by inverse processing should be considered to determine whether the intensity of these attacks is realistic. In this study, objective audio quality measurement was applied to audio signals, including typical perceptual coding, MP3, tandem MP3, and MPEG4AAC, and reversible signal processing techniques, including linear speed change, noise addition, frequency scale modification, time scale modification, bandpass filtering and echo addition. The results provide requirements that watermarking should be robust against and a list of attacks that are feasible against high-quality audio watermarking. © 2013 Acoustical Society of America.
Le Gall F.,Tokyo University of Information Sciences
Proceedings of the Annual ACM-SIAM Symposium on Discrete Algorithms | Year: 2012
We present new quantum algorithms for Boolean Matrix Multiplication in both the time complexity and the query complexity settings. As far as time complexity is concerned, our results show that the product of two n x n Boolean matrices can be computed on a quantum computer in time Õ(n 3/2 + nℓ 3/4), where ℓ is the number of non-zero entries in the product, improving over the output-sensitive quantum algorithm by Buhrman and Spalek that runs in Õ(n 3/2√ℓ) time. This is done by constructing a quantum version of a recent algorithm by Lingas, using quantum techniques such as quantum counting to exploit the sparsity of the output matrix. As far as query complexity is concerned, our results improve over the quantum algorithm by Vassilevska Williams and Williams based on a reduction to the triangle finding problem. One of the main contributions leading to this improvement is the construction of a triangle finding quantum algorithm tailored especially for the tripartite graphs appearing in the reduction. Copyright © SIAM.