Hiroshi Imai

CO J=3-2 Emission from the "Water Fountain" Sources IRAS 16342-3814 and IRAS 18286-0959 (2009)

Imai, Hiroshi, He, Jin-Hua, Nakashima, Jun-ichi, Ukita, Nobuharu, Deguchi, Shuji, Koning, Nico

We observed CO J=3-2 emission from the "water fountain" sources, which exhibit high-velocity collimated stellar jets traced by water maser emission, with the Atacama Submillimeter Telescope...

Fourier Analytic Approach to Phase Estimation (2008)

Imai, Hiroshi, Hayashi, Masahito

For a unified analysis on the phase estimation, we focus on the limiting distribution. It is shown that the limiting distribution can be given by the absolute square of the Fourier transform of $L^2$...

VLBI Astrometry of AGB Variables with VERA -- A Semiregular Variable S Crateris -- (2008)

Nakagawa, Akiharu, Tsushima, Miyuki, Ando, Kazuma, Bushimata, Takeshi, Choi, Yoon Kyung, Hirota, Tomoya, ...

We present a distance measurement for the semiregular variable S Crateris (S Crt) based on its annual parallax. With the unique dual beam system of the VLBI Exploration for Radio Astrometry (VERA)...

Astrometry of H$_{2}$O Masers in Nearby Star-Forming Regions with VERA. III. IRAS 22198+6336 in L1204G (2008)

Hirota, Tomoya, Ando, Kazuma, Bushimata, Takeshi, Choi, Yoon Kyung, Honma, Mareki, Imai, Hiroshi, ...

We present results of multi-epoch VLBI observations with VERA (VLBI Exploration of Radio Astrometry) of the 22 GHz H$_{2}$O masers associated with a young stellar object (YSO) IRAS 22198+6336 in a...

Distance to VY Canis Majoris with VERA (2008)

Choi, Yoon Kyung, Hirota, Tomoya, Honma, Mareki, Kobayashi, Hideyuki, Bushimata, Takeshi, Imai, Hiroshi, ...

We report astrometric observations of H2O masers around the red supergiant VY Canis Majoris (VY CMa) carried out with VLBI Exploration of Radio Astrometry (VERA). Based on astrometric monitoring for...

Distance to NGC 281 in a Galactic Fragmenting Superbubble: Parallax Measurements with VERA (2008)

Sato, Mayumi, Hirota, Tomoya, Honma, Mareki, Kobayashi, Hideyuki, Sasao, Tetsuo, Bushimata, Takeshi, ...

We have used the Japanese VLBI array VERA to perform high-precision astrometry of an H2O maser source in the Galactic star-forming region NGC 281 West, which has been considered to be part of a...

76 No. 40 Matsumoto et al. Can General-Purpose Compression Schemes Really Compress DNA Sequences? (2008)

Toshiko Matsumoto, Kunihiko Sadakane, Hiroshi Imai, Takumi Okazaki

Today, more and more DNA sequences are becoming available. The information about DNA sequences are stored in molecular biology databases. The size and importance of these databases will be bigger and...

Dynamic Weighted Voronoi Diagrams and Weighted Minimax Matching of Two Corresponding Point Sets (2008)

Keiko Imai, Hiroshi Imai

Dedicated to Professor Masao Iri on the occasion of his 65th birthday A weighted geometric fitting problem between two corresponding sets of points is to minimize the maximum weighted distance...

Molecular Line Observations of the SiO Maser Source IRAS 19312+1950 (2008)

Nakashima, Jun-ichi, Deguchi, Shuji, Imai, Hiroshi, Kemball, Athol

IRAS 19312+1950 is a unique SiO maser source, exhibiting a rich set of molecular radio lines, although SiO maser sources are usually identified as oxygen-rich evolved stars, in which chemistry is...

Computing the Tutte Polynomial of a Graph and the Jones Polynomial of an Alternating Link of Moderate Size (2007)

Kyoko Sekine, Kyoko Sekine, Hiroshi Imai, Hiroshi Imai, Seiichiro Tani, Seiichiro Tani

The problem of computing the Tutte polynomial of a graph has been a hot topic in recent years, because its computation is very useful not only in graph theory but also in many problems in statistical...

Parallel Multiple Alignments and Their Implementation on CM5 (2007)

Naoto Ukiyama, Hiroshi Imai

This paper addresses several issues in parallel multiple alignments, and reports some preliminary computational results of their implementation on CM5. Use of parallelism in the diagonal direction is...

Compact Encoding of the Web Graph Exploiting Various Power Laws Statistical Reason Behind Link Database (2007)

Yasuhito Asano, Tsuyoshi Ito, Hiroshi Imai, Masashi Toyoda, Masaru Kitsuregawa

Abstract. Compact encodings of the web graph are required in order to keep the graph on main memory and to perform operations on the graph efficiently. Link2, the second version of the Link Database...

PAPER Fast Algorithms for k-word Proximity Search (2007)

Kunihiko Sadakane, Hiroshi Imai, Regular Member

SUMMARY When we search from a huge amount of documents, we often specify several keywords and use conjunctive queries to narrow the result of the search. Though the searched

Improving the Speed of LZ77 Compression by Hashing and Su#x Sorting (2007)

Kunihiko Sadakane, Hiroshi Imai, Regular Member

SUMMARY Two new algorithms for improving the speed of the LZ77 compression are proposed. One is based on a new hashing algorithm named two-level hashing that enables fast longest match searching from...

Finding Meaningful Regions Containing Given Keywords from Large Text Collections (2007)

Kunihiko Sadakane, Hiroshi Imai

Introduction When we search a large text collection for documents we want, we will specify some keywords and we obtain documents containing the keywords. Because the search result contains many...

SUMMARY This (2007)

Hiroshi Imai, Mary Inaba

sur eysrsfiA tprSNSLfi in the investigation of the under#fi5 # discr # pr ximitystr"Mfi5#Y of geometrN clusterMfi with rth ect to the diverfiAYY ininforMfi5#N geometr. Geometr # clusterLL...

SUMMARY (2007)

Tetsuo Shibuya, Hiroshi Imai, Shigeki Nishimura, Hiroshi Shimoura, Kenji Tenmoku

databases for navigation, users raise various typ es of queries concerning route guidance. The most fundamental query is a shortest-route query, but, as dynamical tra#c information newly becomes...

Stellar molecular jets traced by maser emission (2007)

Imai, Hiroshi

Highly collimated jets found in AGB and post-AGB stars are expected to play an important role for shaping planetary nebulae. Recent VLBI observations of H2O maser sources have revealed that some of...

Astrometry of Water Maser Sources in Nearby Molecular Clouds with VERA - II. SVS 13 in NGC 1333 (2007)

Hirota, Tomoya, Bushimata, Takeshi, Choi, Yoon Kyung, Honma, Mareki, Imai, Hiroshi, Iwadate, Kenzaburo, ...

We report on the results of multi-epoch VLBI observations with VERA (VLBI Exploration of Radio Astrometry) of the 22 GHz H2O masers associated with the young stellar object SVS 13 in the NGC 1333...

Astrometry of Galactic Star Forming Region Sharpless 269 with VERA : Parallax Measurements and Constraint on Outer Rotation Curve (2007)

Honma, Mareki, Bushimata, Takeshi, Choi, Yoon Kyung, Hirota, Tomoya, Imai, Hiroshi, Iwadate, Kenzaburo, ...

We have performed high-precision astrometry of H2O maser sources in Galactic star forming region Sharpless 269 (S269) with VERA. We have successfully detected a trigonometric parallax of 189+/-8...

The spatio-kinematical structure and distance of the pre-planetary nebula IRAS 19134+2131 (2007)

Imai, Hiroshi, Sahai, Raghvendra, Morris, Mark

Using the VLBA, we have observed H2O maser emission in the pre-planetary nebula IRAS 19134+2131(I19134), in which the H2O maser spectrum has two groups of emission features separated in radial...

Distance to Orion KL Measured with VERA (2007)

Hirota, Tomoya, Bushimata, Takeshi, Choi, Yoon Kyung, Honma, Mareki, Imai, Hiroshi, Iwadate, Kenzaburo, ...

We present the initial results of multi-epoch VLBI observations of the 22 GHz H2O masers in the Orion KL region with VERA (VLBI Exploration of Radio Astrometry). With the VERA dual-beam receiving...

Absolute Proper Motions of H2O Masers Away from the Galactic Plane Measured with VERA in the "Superbubble" Region NGC 281 (2007)

Sato, Mayumi, Hirota, Tomoya, Honma, Mareki, Kobayashi, Hideyuki, Sasao, Tetsuo, Bushimata, Takeshi, ...

We report on absolute proper-motion measurements of an H2O maser source in the NGC 281 West molecular cloud, which is located ~320 pc above the Galactic plane and is associated with an HI loop...

Voronoi Diagrams and a Numerical Estimation of a Quantum Channel Capacity (2006)

Kato, Kimikazu, Oto, Mayumi, Imai, Hiroshi, Imai, Keiko

We give a new geometric interpretation of quantum pure states. Using Voronoi diagrams, we reinterpret the structure of the space of pure states as a subspace of the quantum state space. In addition...

A collimated jet and an infalling-rotating disk in G192.16-3.84 traced by H2O maser emission (2006)

Imai, Hiroshi, Omodaka, Toshihiro, Hirota, Tomoya, Umemoto, Tomofumi, Sorai, Kazuo, Kondo, Tetsuro

We report H2O masers associated with the massive-star forming region G192.16-3.84 observed with the new Japan VLBI network at three epochs spanned for two months, which have revealed the...

On a Geometric Structure of Pure Multi-qubit Quantum States and Its Applicability to a Numerical Computation (2006)

Kato, Kimikazu, Oto, Mayumi, Imai, Hiroshi, Imai, Keiko

For one-qubit pure quantum states, it is already proved that the Voronoi diagrams with respect to two distances -- Euclidean distance and the quantum divergence -- coincide. This fact is a support...

On the Relationship between Convex Bodies Related to Correlation Experiments with Dichotomic Observables (2006)

Avis, David, Imai, Hiroshi, Ito, Tsuyoshi

In this paper we explore further the connections between convex bodies related to quantum correlation experiments with dichotomic variables and related bodies studied in combinatorial optimization,...

Voronoi Diagrams for Pure 1-qubit Quantum States (2006)

Kato, Kimikazu, Oto, Mayumi, Imai, Hiroshi, Imai, Keiko

1-qubit quantum states form a space called the three-dimensional Bloch ball. To compute Holevo capacity, Voronoi diagrams in the Bloch ball with respect to the quantum divergence have been used as a...

Generating facets for the cut polytope of a graph by triangular elimination (2006)

Avis, David, Imai, Hiroshi, Ito, Tsuyoshi

The cut polytope of a graph arises in many fields. Although much is known about facets of the cut polytope of the complete graph, very little is known for general graphs. The study of Bell...

Water maser motions in W3(OH) and a determination of its distance (2006)

Hachisuka, Kazuya, Brunthaler, Andreas, Menten, Karl M., Reid, M. Jamila, Imai, Hiroshi, Hagiwara, Yoshiaki, ...

We report phase-referencing VLBA observations of H2O masers near the star-forming region W3(OH) to measure their parallax and absolute proper motions. The measured annual parallax is 0.489 ±0.017...

Water maser motions in W3(OH) and a determination of its distance (2006)

Hachisuka, Kazuya, Brunthaler, Andreas, Menten, Karl M., Reid, M. Jamila, Imai, Hiroshi, Hagiwara, Yoshiaki, ...

We report phase-referencing VLBA observations of H2O masers near the star-forming region W3(OH) to measure their parallax and absolute proper motions. The measured annual parallax is 0.489 ±0.017...

Water maser motions in W3(OH) and a determination of its distance (2006)

Hachisuka, Kazuya, Brunthaler, Andreas, Menten, Karl M., Reid, M. Jamila, Imai, Hiroshi, Hagiwara, Yoshiaki, ...

We report phase-referencing VLBA observations of H2O masers near the star-forming region W3(OH) to measure their parallax and absolute proper motions. The measured annual parallax is 0.489 ±0.017...

Water maser motions in W3(OH) and a determination of its distance (2006)

Hachisuka, Kazuya, Brunthaler, Andreas, Menten, Karl M., Reid, M. Jamila, Imai, Hiroshi, Hagiwara, Yoshiaki, ...

We report phase-referencing VLBA observations of H2O masers near the star-forming region W3(OH) to measure their parallax and absolute proper motions. The measured annual parallax is 0.489 ±0.017...

Water maser motions in W3(OH) and a determination of its distance (2006)

Hachisuka, Kazuya, Brunthaler, Andreas, Menten, Karl M., Reid, M. Jamila, Imai, Hiroshi, Hagiwara, Yoshiaki, ...

We report phase-referencing VLBA observations of H2O masers near the star-forming region W3(OH) to measure their parallax and absolute proper motions. The measured annual parallax is 0.489 ±0.017...

Identification and characterization of two novel classes of small RNAs in the mouse germline: retrotransposon-derived siRNAs in oocytes and germline small RNAs in testes (2006)

Watanabe, Toshiaki, Takeda, Atsushi, Tsukiyama, Tomoyuki, Mise, Kazuyuki, Okuno, Tetsuro, Sasaki, Hiroyuki, ...

Small RNAs ranging in size between 18 and 30 nucleotides (nt) are found in many organisms including yeasts, plants, and animals. Small RNAs are involved in the regulation of gene expression through...

Identification and characterization of two novel classes of small RNAs in the mouse germline: retrotransposon-derived siRNAs in oocytes and germline small RNAs in testes (2006)

Watanabe, Toshiaki, Takeda, Atsushi, Tsukiyama, Tomoyuki, Mise, Kazuyuki, Okuno, Tetsuro, Sasaki, Hiroyuki, ...

Small RNAs ranging in size between 18 and 30 nucleotides (nt) are found in many organisms including yeasts, plants, and animals. Small RNAs are involved in the regulation of gene expression through...

Inward Motions of the Compact SiO Masers Around VX Sagittarii (2005)

Chen, Xi, Shen, Zhi-Qiang, Imai, Hiroshi, Kamohara, Ryuichi

We report Very Long Baseline Array (VLBA) observations of 43 GHz v=1, J=1-0 SiO masers in the circumstellar envelope of the M-type semi-regular variable star VX Sgr at 3 epochs during 1999 April-May....

Bell inequalities stronger than the CHSH inequality for 3-level isotropic states (2005)

Ito, Tsuyoshi, Imai, Hiroshi, Avis, David

We show that some two-party Bell inequalities with two-valued observables are stronger than the CHSH inequality for 3 \otimes 3 isotropic states in the sense that they are violated by some isotropic...

Two-Party Bell Inequalities Derived from Combinatorics via Triangular Elimination (2005)

Avis, David, Imai, Hiroshi, Ito, Tsuyoshi, Sasaki, Yuuya

We establish a relation between the two-party Bell inequalities for two-valued measurements and a high-dimensional convex polytope called the cut polytope in polyhedral combinatorics. Using this...

Two-party Bell inequalities derived from combinatorics via triangular elimination (2005)

David Avis, Hiroshi Imai, Tsuyoshi Ito, Yuuya Sasaki

Bell inequalities, originally introduced as a method to prove that some quantum states show nonlocal behavior, are now studied as a method to capture the extent of the nonlocality of quantum states....

Deriving Tight Bell Inequalities for 2 Parties with Many 2-valued Observables from Facets of Cut Polytopes (2004)

Avis, David, Imai, Hiroshi, Ito, Tsuyoshi, Sasaki, Yuuya

Relatively few families of Bell inequalities have previously been identified. Some examples are the trivial, CHSH, I_{mm22}, and CGLMP inequalities. This paper presents a large number of new families...

Qubit Channels Which Require Four Inputs to Achieve Capacity: Implications for Additivity Conjectures (2004)

Hayashi, Masahito, Imai, Hiroshi, Matsumoto, Keiji, Ruskai, Mary Beth, Shimono, Toshiyuki

An example is given of a qubit quantum channel which requires four inputs to maximize the Holevo capacity. The example is one of a family of channels which are related to 3-state channels. The...

Deriving tight Bell inequalities for 2 parties with many 2-valued observables from facets of cut polytopes. arXiv:quant-ph/0404014 (2004)

David Avis, Hiroshi Imai, Tsuyoshi Ito, Yuuya Sasaki

Relatively few families of Bell inequalities have previously been identified. Some examples are the trivial, CHSH, Imm22, and CGLMP inequalities. This paper presents a large number of new families of...

Oogenesin Is a Novel Mouse Protein Expressed in Oocytes and Early Cleavage-Stage Embryos1 (2003)

Naojiro Minami, Akira Aizawa, Ryo Ihara, Masakazu Miyamoto, Akihiro Ohashi, Hiroshi Imai

We describe a new gene (Oogenesin) that is expressed through oogenesis and early embryogenesis in the mouse. De novo expression starts at 15.5 dpc (days postcoitum) in the ovary, which coincides with...

A birth and growth of a collimated molecular jet from an AGB star (2003)

Imai, Hiroshi, Diamond, Philip J.

With the VLBA, we have observed water masers associated with the OH/IR star, W43A, which trace a birth and growth of a molecular jet. The water masers exhibit the collimated distribution (1700 AU: 20...

Linear Polarization Observations of Water Masers in W3 IRS5 (2003)

Imai, Hiroshi, Horiuchi, Shinji, Deguchi, Shuji, Kameya, Osamu

We present a magnetic field mapping of water maser clouds in the star-forming region W3 IRS5, which has been made on the basis of the linear polarization VLBI observation. Using the Very Long...

The 3-D kinematics of water masers around the semiregular variable RT Virginis (2003)

Imai, Hiroshi, Shibata, Katsunori M., Marvel, Kevin B., Diamond, Philip J., Sasao, Tetsuo, Miyoshi, Makoto, ...

We report observations of water masers around the semiregular variable RT Virginis (RT Vir), which have been made with the Very Long Baseline Array (VLBA) of the National Radio Astronomy Observatory...

Shor-Preskill-type security proof for concatenated Bennett-Brassard 1984 quantum-key-distribution protocol (2003)

Hwang, Won-Young, Matsumoto, Keiji, Imai, Hiroshi, Kim, Jaewan, Lee, Hai-Woong

©2003 The American Physical Society URL: http://link.aps.org/abstract/PRA/v67/e024302 DOI: 10.1103/PhysRevA.67.024302 PACS: 03.67.Dd

MuERV-L Is One of the Earliest Transcribed Genes in Mouse One-Cell Embryos1 (2003)

Daisuke Kigami, Naojiro Minami, Hanae Takayama, Hiroshi Imai

The expression pattern and function of the murine endogenous retrovirus-like (MuERV-L) gene in mouse preimplantation embryos was investigated. MuERV-L was rapidly transcribed from the beginning of S...

Finding Neighbor Communities in the Web Using Inter-Site Graph (2003)

Yasuhito Asano, Hiroshi Imai, Masashi Toyoda, Masaru Kitsuregawa

In recent years, link-based information retrieval methods from the Web are developed. A framework of these methods is a Web graph using pages as vertices and Web-links as edges. In the last year, the...

Simulating the Effects of Quantum Error-correction Schemes (2002)

Niwa, Jumpei, Matsumoto, Keiji, Imai, Hiroshi

It is important to protect quantum information against decoherence and operational errors, and quantum error-correcting (QEC) codes are the keys to solving this problem. Of course, just the existence...

3-D Kinematics of Water Masers in the W51A Region (2002)

Imai, Hiroshi, Watanabe, Teruhiko, Nishio, Masanori, Omodaka, Toshihiro, Kameya, Osamu, Miyaji, Takeshi, ...

We report proper motion measurements of water masers in the massive-star forming region W51A and the analyses of the 3-D kinematics of the masers in three maser clusters of W51A (W51 North, Main, and...

Dualistic computational algebraic analyses of primal and dual minimum cost flow problems on acyclic tournament graphs (2002)

Ishizeki, Takayuki, Nakayama, Hiroki, Imai, Hiroshi

To integer programming problems, computational algebraic approaches using Grobner bases or standard pairs via the discreteness of toric ideals have been studied in recent years. Although these...

Phase-covariant quantum cloning of qudits (2002)

Fan, Heng, Imai, Hiroshi, Matsumoto, Keiji, Wang, Xiang-Bin

We study the phase-covariant quantum cloning machine for qudits, i.e. the input states in d-level quantum system have complex coefficients with arbitrary phase but constant module. A cloning unitary...

Analysis of Absorbing Times of Quantum Walks (2002)

Yamasaki, Tomohiro, Kobayashi, Hirotada, Imai, Hiroshi

Quantum walks are expected to provide useful algorithmic tools for quantum computation. This paper introduces absorbing probability and time of quantum walks and gives both numerical simulation...

Quantify entanglement by concurrence hierarchy (2002)

Fan, Heng, Matsumoto, Keiji, Imai, Hiroshi

We define the concurrence hierarchy as d-1 independent invariants under local unitary transformations in d-level quantum system. The first one is the original concurrence defined by Wootters et al in...

General-Purpose Parallel Simulator for Quantum Computing (2002)

Niwa, Jumpei, Matsumoto, Keiji, Imai, Hiroshi

With current technologies, it seems to be very difficult to implement quantum computers with many qubits. It is therefore of importance to simulate quantum algorithms and circuits on the existing...

One-way probabilistic reversible and quantum one-counter automata,” Theor (2002)

Tomohiro Yamasaki, Hirotada Kobayashi, Yuuki Tokunaga, Hiroshi Imai

Abstract Kravtsev introduced 1-way quantum 1-counter automata (1Q1CAs), and showed that several non-context-free languages can be recognized by bounded error 1Q1CAs. In this paper, we first show that...

Efficient induction of rat large intestinal tumors with a new spectrum of mutations by intermittent administration of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine in combination with a high fat diet (2002)

Ubagai, Tsuneyuki, Ochiai, Masako, Kawamori, Toshihiko, Imai, Hiroshi, Sugimura, Takashi, Nagao, Minako, ...

In the present study we have established novel intermittent protocols featuring a high fat (HF) diet for efficient induction of large intestinal tumors with a relatively small amount of...

Cloning of symmetric d-level photonic states in physical systems (2001)

Fan, Heng, Weihs, Gregor, Matsumoto, Keiji, Imai, Hiroshi

Optimal procedures play an important role in quantum information. It turns out that some naturally occurring processes like emission of light from an atom can realize optimal transformations. Here we...

VLBI Monitoring Observations of Water Masers Around the Semi-Regular Variable Star R Crateris (2001)

Ishitsuka, Jose K., Imai, Hiroshi, Omodaka, Toshihiro, Ueno, Munetaka, Kameya, Osamu, Sasao, Tetsuo, ...

We monitored water-vapor masers around the semi-regular variable star R Crateris with the Japanese VLBI Network (J-Net) at the 22 GHz band during four epochs with intervals of one month. The relative...

Two-way Quantum One-counter Automata (2001)

Yamasaki, Tomohiro, Kobayashi, Hirotada, Imai, Hiroshi

After the first treatments of quantum finite state automata by Moore and Crutchfield and by Kondacs and Watrous, a number of papers study the power of quantum finite state automata and their...

A universal cloner allowing the input to be arbitrary states in symmetric subspace (2001)

Fan, Heng, Matsumoto, Keiji, Wang, Xiang-Bin, Imai, Hiroshi, Wadati, Miki

A generalized universal quantum cloning machine is proposed which allows the input to be arbitrary states in symmetric subspace. And it reduces to the universal quantum cloning machine (UQCM) if the...

High susceptibility of Scid mice to colon carcinogenesis induced by azoxymethane indicates a possible caretaker role for DNA-dependent protein kinase (2001)

Ochiai, Masako, Ubagai, Tsuneyuki, Kawamori, Toshihiko, Imai, Hiroshi, Sugimura, Takashi, Nakagama, Hitoshi

Severe combined immunodeficiency (Scid) mice have defects in V(D)J recombination and DNA double-strand breaks repair caused by an inherited genetic defect in the catalytic subunit of DNA-dependent...

Implementing the context tree weighting method for text compression (2000)

Kunihiko Sadakane, Takumi Okazaki, Hiroshi Imai

Context tree weighting method is a universal compression algorithm for FSMX sources. Though we expect that it will have good compression ratio in practice, it is di#cult to implement it and in many...

Sequencing by hybridization in the presence of hybridization errors (2000)

Koichiro Doi, Hiroshi Imai

DNA sequencing is a very important problem in genomics. Several different sequencing methods are currently utilized. One promising method uses a sequencing chip to obtain information about the...

A greedy algorithm for minimizing the number of primers in multiple PCR experiments (1999)

Koichiro Doi, Hiroshi Imai

The selection of a suitable set of primers is very important for polymerase chain reaction (PCR) experiments. Most existing algorithms for primer selection are concerned with producing a primer pair...

Text Retrieval by using k-word Proximity Search (1999)

Kunihiko Sadakane, Hiroshi Imai

When we search from a huge amount of documents, we often specify several keywords and use conjunctive queries to narrow the result of the search. Though the

A Cooperative Distributed Text Database Management Method Unifying Search and Compression Based on the Burrows-Wheeler Transformation (1999)

Kunihiko Sadakane, Hiroshi Imai

A new text database management method for distributed cooperative environments is proposed, which can collect texts in distributed sites through a network of narrow bandwidth and enables fulltext...

On K-Word Proximity Search (1999)

Kunihiko Sadakane, Hiroshi Imai

this paper, we propose two algorithms for finding documents in which all given keywords appear in neighboring places. One is based on plane-sweep algorithm and the other is based on...

Enumerating triangulations for products of two simplices and for arbitrary configurations of points (1997)

Fumihiko Takeuchi, Hiroshi Imai

Abstract. We propose algorithms to enumerate (1) classes of regular triangulations in respect of symmetry for products of two simplices and (2) all triangulations, regular or not, for arbitrary...

Enumerating Suboptimal Alignments of Multiple Biological Sequences Efficiently (1997)

Tetsuo Shibuya, Hiroshi Imai

this paper, we first discuss the method to obtain E1 , which represents all aligned groups of residues in optimal and suboptimal alignments which are at most 1 worse than the optimal, by extending...

Detour Queries in Geographical Databases for Navigation and Related Algorithm Animations (1996)

Tetsuo Shibuya, Hiroshi Imai, Shigeki Nishimura, Hiroshi Shimoura, Kenji Tenmoku

In geographical databases for navigation, users raise various types of queries concerning route guidance. The most fundamental query is a shortest-route query, but, as dynamical traffic information...

Combinatorial and Geometric Approaches to Counting Problems on Linear Matroids, Graphic Arrangements and Partial Orders (1996)

Hiroshi Imai, Satoru Iwata, Kyoko Sekine, Kensyu Yoshida

For typical #P-hard problems on graphs, we have recently proposed an approach to solve those problems of moderate size rigorously by means of the binary decision diagram, BDD [12, 13]. This paper...

KEY WORDS AND PHRASES Network reliability, #P-completeness, Binary Decision Diagram (BDD) (1995)

Kyoko Sekine, Kyoko Sekine, Hiroshi Imai, Hiroshi Imai

Recently, fully polynomial randomized approximation scheme for computing the network reliability have been developed by Alon, Frieze, Welsh [1] and Karger [10]. Since the computation of the network...

Ordered Binary Decision Diagrams, Graph Theory and Computational Geometry (1995)

Hiroshi Imai, Hiroshi Imai, Seiichiro Tani, Seiichiro Tani, Kyoko Sekine, Kyoko Sekine

Ordered binary decision diagrams (OBDDs in short) have been shown as a powerful paradigm in handling Boolean functions and have been applied to many fields such as VLSI CAD, AI, combinatorics, etc....

Computing the Tutte Polynomial of a Graph and the Jones Polynomial of an Alternating Link of Moderate Size (1995)

Kyoko Sekine, Kyoko Sekine, Hiroshi Imai, Hiroshi Imai, Seiichiro Tani, Seiichiro Tani

The problem of computing the Tutte polynomial of a graph has been a hot topic in recent years, because its computation is very useful not only in graph theory but also in many problems in statistical...

Ordered Binary Decision Diagrams, Graph Theory and Computational Geometry (1995)

Hiroshi Imai, Hiroshi Imai, Seiichiro Tani, Seiichiro Tani, Kyoko Sekine, Kyoko Sekine

Ordered binary decision diagrams (OBDDs in short) have been shown as a powerful paradigm in handling Boolean functions and have been applied to many fields such as VLSI CAD, AI, combinatorics, etc....

Fast A* Algorithms for Multiple Sequence Alignment (1994)

Takahiro Ikeda, Hiroshi Imai

The multiple alignment of the sequences of DNA and proteins is applicable to various important fields in molecular biology. Although the approach based on Dynamic Programming is well-known for this...

Probing a Set of Hyperplanes by Lines and Related Problems (1993)

Yasukazu Aoki, Hiroshi Imai, Keiko Imai, David Rappaport

Suppose that for a set H of n unknown hyperplanes in the Euclidean d-dimensional space, a line probe is available which reports the set of intersection points of a query line with the hyperplanes....

Computing Simple Circuits from a Set of Line Segments (1990)

David Rappaport, Hiroshi Imai, Godfried T. Toussaint

We address the problem of connecting line segments to form the boundary of a simple polygon --- a simple circuit. However, not every set of segments can be so connected. We present an O(n log n)-time...

13. An Experimental Study on Mechanism of Implosion Earthquakes during the 1973 Successive Eruptive Activity of Asama Volcano (1983)

Imai, Hiroshi

In the course of eruptive activity of Asama Volcano in 1973, successive eruptions occurred during the period 16 to 18 February. Implosion earthquakes associated with the eruptive activity were...

14. A Short Comment on the 1982 Explosive Eruption of Asama Volcano, Central Honshu, Japan (1983)

Imai, Hiroshi

Asama Volcano erupted on April 26, 1982, after a nine year dormancy. A study is carried out for the three component seismograms of the explosion earthquake associated with the first break which took...

Implosion Earthquakes Associated with the 1973 Eruptive Activity of Asama Volcano (1982)

Imai, Hiroshi

Several successive small and gentle eruptions were observed during Feb. 16-18 in the course of the 1973 eruptive activity of Asama Volcano, central Honshu, Japan. Many earthquakes associated with the...

Minisatellite instability in severe combined immunodeficiency mouse cells

Imai, Hiroshi, Nakagama, Hitoshi, Komatsu, Kenshi, Shiraishi, Taizo, Fukuda, Hirokazu, Sugimura, Takashi, ...

We have recently found that okadaic acid, which shows strong inhibitory activity on protein serine/threonine phosphatases and tumor-promoting activity in vivo and in vitro, induces minisatellite...

Minisatellite instability in severe combined immunodeficiency mouse cells

Imai, Hiroshi, Nakagama, Hitoshi, Komatsu, Kenshi, Shiraishi, Taizo, Fukuda, Hirokazu, Sugimura, Takashi, ...

We have recently found that okadaic acid, which shows strong inhibitory activity on protein serine/threonine phosphatases and tumor-promoting activity in vivo and in vitro, induces minisatellite...

Identification and characterization of two novel classes of small RNAs in the mouse germline: retrotransposon-derived siRNAs in oocytes and germline small RNAs in testes

Watanabe, Toshiaki, Takeda, Atsushi, Tsukiyama, Tomoyuki, Mise, Kazuyuki, Okuno, Tetsuro, Sasaki, Hiroyuki, ...

Small RNAs ranging in size between 18 and 30 nucleotides (nt) are found in many organisms including yeasts, plants, and animals. Small RNAs are involved in the regulation of gene expression through...