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Journal Articles

Multi-step magnetic transitions in EuNiIn$$_4$$

Ikeda, Shugo*; Kaneko, Koji; Tanaka, Yuki*; Kawasaki, Takuro; Hanashima, Takayasu*; Munakata, Koji*; Nakao, Akiko*; Kiyanagi, Ryoji; Ohara, Takashi; Mochizuki, Kensei*; et al.

Journal of the Physical Society of Japan, 89(1), p.014707_1 - 014707_7, 2020/01

 Times Cited Count:1 Percentile:12.02(Physics, Multidisciplinary)

Journal Articles

Measurements of gamma-ray emission probabilities in the decay of americium-244g

Nakamura, Shoji; Terada, Kazushi*; Kimura, Atsushi; Nakao, Taro*; Iwamoto, Osamu; Harada, Hideo; Uehara, Akihiro*; Takamiya, Koichi*; Fujii, Toshiyuki*

Journal of Nuclear Science and Technology, 56(1), p.123 - 129, 2019/01

 Times Cited Count:1 Percentile:11.15(Nuclear Science & Technology)

Accurate data of $$gamma$$-ray emission probabilities are frequently needed when one quantitatively determines the amount of isotope by $$gamma$$-ray measurements or obtains neutron capture cross-sections using them. Americium-243, one of the most important minor actinides, produces $$^{244}$$Am after neutron capture. The 744-keV $$gamma$$-ray decaying from the ground state of $$^{244}$$Am has a relatively large $$gamma$$-ray emission probability c.a. 66%, however, its uncertainty is as large as 29%. The uncertainty of the $$gamma$$-ray emission probability leads to a major factor of the systematic uncertainty on determining an amount of isotope, and therefore the $$gamma$$-ray emission probability was measured by using an activation method and an examined level structure of $$^{244}$$Cm. In this study, the emission probability of 744-keV $$gamma$$ ray was derived as 66.5$$pm$$1.1%, and its uncertainty was improved from 29% to 2%.

Journal Articles

Inferring partial orders of nodes for hierarchical network layout

Wu, H.-Y.*; Takahashi, Shigeo*; Miyamura, Hiroko; Ozahata, Satoshi*; Nakao, Akihiro*

Electronic Imaging, 2017(1), p.118 - 130, 2017/01

Extracting hierarchical structures from networks provides us with an effective means of visualizing them, especially when they contain complicated node connectivities such as those in traffic and distributed networks. This paper presents an algorithm for inferring such partial orders by optimizing the network hierarchies along flow paths that are given as input. We study several network examples to demonstrate the feasibility of the proposed approach including course dependency charts, railway networks, and P2P networks.

Journal Articles

Inferring partial orders of nodes for hierarchical network layout

Wu, H.-Y.*; Takahashi, Shigeo*; Miyamura, Hiroko; Ozahata, Satoshi*; Nakao, Akihiro*

Journal of Imaging Science and Technology, 60(6), p.060407_1 - 060407_13, 2016/11

 Times Cited Count:0 Percentile:0.02(Imaging Science & Photographic Technology)

Extracting hierarchical structures from networks provides us with an effective means of visualizing them, especially when they contain complicated node connectivities such as those in traffic and distributed networks. This paper presents an algorithm for inferring such partial orders by optimizing the network hierarchies along flow paths that are given as input. We study several network examples to demonstrate the feasibility of the proposed approach including course dependency charts, railway networks, and P2P networks.

Journal Articles

Visualization of overlay network using autonomous system relationships

Miyamura, Hiroko; Hu, H.-Y.*; Yoshida, Masahiro*; Ozahata, Satoshi*; Nakao, Akihiro*; Takahashi, Shigeo*

Shingaku Giho, 112(463), p.577 - 582, 2013/03

This report presents a method for visualizing scale-free networks including Overlay networks as an typical example. Visualizing large-scale and complicated networks such as social networks has recently been very popular while conventional network visualization techniques cannot allow us to understand the topological structure of the scale-free networks. This is because the vertex degrees vary at an exponential rate in the scale-free network and thus special attention should be given when visualizing the network connectivity and analyzing the network traffic there. In this report, we employ the hierarchical representation of the scale-free network by referring to their vertex degrees and autonomous system relationships, so that we can clearly visualize the topological structure of the network in 3D space and retrieve the traffic paths over the network.

Journal Articles

Visualization system for large-scale network data; A Large scale data capture technique

Miyamura, Hiroko; Ozahata, Satoshi*; Nakao, Akihiro*; Kawashima, Konosuke*; Teshima, Naoya*; Suzuki, Yoshio; Takemiya, Hiroshi

Zen NUA C&C Shisutemu Yuzakai Heisei-22-Nendo Rombunshu (CD-ROM), 14 Pages, 2011/02

Recently, construction of large-scale distributed file systems has become easier because of reduced hardware costs and the availability of large hard disks and faster networks. However, if the sizes and/or numbers become too large, occasionally even the data server manager cannot control the storage situation of the files. Therefore, we propose the concept of adaptive network graph display, in which the graph style can be changed according to the details of what the user details is observing, and construct a visualization system based on this concept. When observing data globally, the proposed system selectively displays information based on the clustering result, and when observing data locally, the system displays detailed information. This technique is a basic technology for computational science to achieve large-scale datasets handling and knowledge succession which is a problem in atomic energy related fields.

Journal Articles

Adaptive visualization for analyzing large-scale network datasets

Miyamura, Hiroko; Ozahata, Satoshi*; Nakao, Akihiro*; Kawashima, Konosuke*

Shingaku Giho, 110(190), p.103 - 108, 2010/09

In this paper, we propose a visualization technique for handling large-scale experiment datasets in distributed file system. Traditional network visualization techniques have problem that not all data can be displayed at the same time because the file-sharing network data is too large-scale. Therefore, we propose a concept of adaptive network graph display, in which the graph style can be changed according to the details of user's observation. We construct a visualization system based on this concept. When observing data globally, the proposed system selectively displays information based on the clustering result, and when observing data locally, the system displays detailed information. This technique is a basic technology for computational science to achieve large-scale datasets handling which is a problem in atomic energy related fields.

Journal Articles

A Network visualization system with interactive operations for important nodes discovery

Miyamura, Hiroko; Ozahata, Satoshi*; Nakao, Akihiro*; Kawashima, Konosuke*; Suzuki, Yoshio

Denki Gakkai Kenkyukai Shiryo, Sangyo Keisoku Seigyo Kenkyukai (IIC-10-85), p.27 - 32, 2010/03

We propose a network visualization system for a file-sharing network data-set. The network dataset consists of the information on nodes and links. As the number of links increases, the visualization of the network becomes challenging since the links usually cross over one another, which makes it hard to understand the structure of the network through the visualization. In order to present a network structure clearly and to identify keynodes that play important roles in the network, we propose a network visualization system. In this research, we propose additional techniques that support users searching the key node by using interactive functions such as filtering and node arranging.

Journal Articles

A Network visualization system focusing on important nodes

Miyamura, Hiroko; Ozahata, Satoshi*; Nakao, Akihiro*; Kawashima, Konosuke*; Suzuki, Yoshio

Shingaku Giho, 109(448), p.357 - 362, 2010/03

We propose a visualization system for file-sharing network data. The file-sharing networks have some problems, for example: the contents distribution of the copyright infringement files, an increase in the amount of traffic, and so on. To handle these problems, techniques for observing the network state and controlling the file sharing are proposed. In addition, the proposed techniques realize effective control by giving retrieval control to the key nodes, which are important roles in the file-sharing network.

Journal Articles

A Large scale network visualization for important nodes discovery

Miyamura, Hiroko; Ozahata, Satoshi*; Nakao, Akihiro*; Kawashima, Konosuke*; Suzuki, Yoshio

Shingaku Giho, 109(188), p.85 - 90, 2009/09

We propose a network visualization method for a large-scale file-sharing network dataset. The network dataset has nodes and links that represent the connection between two nodes. When the number of links is large, it is difficult to recognize the structure of the network data, because many links are crossed. In this context, for recognizing the structure and exploring the key nodes, we propose a link-less network visualization method using matrix based representation. In addition, we demonstrate the effectiveness of the proposed method by applying it to the file-sharing network log data.

Journal Articles

The H-Invitational Database (H-InvDB); A Comprehensive annotation resource for human genes and transcripts

Yamasaki, Chisato*; Murakami, Katsuhiko*; Fujii, Yasuyuki*; Sato, Yoshiharu*; Harada, Erimi*; Takeda, Junichi*; Taniya, Takayuki*; Sakate, Ryuichi*; Kikugawa, Shingo*; Shimada, Makoto*; et al.

Nucleic Acids Research, 36(Database), p.D793 - D799, 2008/01

 Times Cited Count:51 Percentile:71.25(Biochemistry & Molecular Biology)

Here we report the new features and improvements in our latest release of the H-Invitational Database, a comprehensive annotation resource for human genes and transcripts. H-InvDB, originally developed as an integrated database of the human transcriptome based on extensive annotation of large sets of fulllength cDNA (FLcDNA) clones, now provides annotation for 120 558 human mRNAs extracted from the International Nucleotide Sequence Databases (INSD), in addition to 54 978 human FLcDNAs, in the latest release H-InvDB. We mapped those human transcripts onto the human genome sequences (NCBI build 36.1) and determined 34 699 human gene clusters, which could define 34 057 protein-coding and 642 non-protein-coding loci; 858 transcribed loci overlapped with predicted pseudogenes.

Journal Articles

Effects of implantation conditions on the luminescence properties of Eu-doped GaN

Nakanishi, Yasuo*; Wakahara, Akihiro*; Okada, Hiroshi*; Yoshida, Akira*; Oshima, Takeshi; Ito, Hisayoshi; Nakao, Setsuo*; Saito, Kazuo*; Kim, Y. T.*

Nuclear Instruments and Methods in Physics Research B, 206, p.1033 - 1036, 2003/05

 Times Cited Count:18 Percentile:74.43(Instruments & Instrumentation)

Photo luminescence properties of GaN implanted with Eu ions were studied. The GaN was epitaxialy grown on sapphire substrate. Multiple-implantation at RT was done to form box profile of Eu at a mean Eu concentration from 2.8$$times$$10$$^{19}$$ to 2.8$$times$$10$$^{20}$$/cm$$^{3}$$. Samples were annealed in NH$$_{3}$$, N$$_{2}$$ at 900-1050$$^{circ}$$C for 5-30 min after implantation. As the result, sharp emission peaks around 621nm which is assigned as 4f-4f transition were observed. The intensity of peaks increases with increasing Eu concentration and saturate at Eu concentrations around 2.8$$times$$10$$^{20}$$/cm$$^{3}$$.

Oral presentation

Shielding experiments at high energy accelerators of FERMI, 6; Measurement of reaction products

Matsumura, Hiroshi*; Kasugai, Yoshimi; Yashima, Hiroshi*; Iwase, Hiroshi*; Matsuda, Norihiro; Kinoshita, Norikazu*; Sanami, Toshiya*; Hagiwara, Masayuki*; Shigyo, Nobuhiro*; Arakawa, Hiroyuki*; et al.

no journal, , 

A gold activation detector was studied as a high energy neutron detector at high radiation field in a series of shielding experiment at Fermi National Accelerator Laboratory. We could measure spallation residual nuclei with wide threshold energy by using a combination method with radiological chemical separation and X-X-$$gamma$$ coincidence detection methods. It was shown the detector was effective for high energy neutron detector.

Oral presentation

A Multilevel graph layout for analysing of large-scale network datasets

Miyamura, Hiroko; Yoshida, Masahiro*; Ozahata, Satoshi*; Takahashi, Shigeo*; Nakao, Akihiro*; Kawashima, Konosuke*

no journal, , 

We propose a multilevel graph layout technique for visualizing large scale network datasets. Large-scale datasets are said to be difficult to analyze and visualize. However, with our technique, the datasets can be displayed in multistep. For instance the outline of network dataset is shown first, and when focused on a certain region, the detailed information is shown as well. By using this technique, users can observe a large scale dataset from the outline to the detail seamlessly, and therefore this is valuable for the structural analysis of network datasets.

Oral presentation

Accuracy improvement of thermal-neutron capture cross-section for Np-237

Nakamura, Shoji; Terada, Kazushi; Kimura, Atsushi; Nakao, Taro; Iwamoto, Osamu; Harada, Hideo; Uehara, Akihiro*; Fujii, Toshiyuki*

no journal, , 

As a part of the AIMAC Project, our group have measured the cross sections for Minor Actinides by an activation method with research reactors. In this presentation, we will clear up the cause of discrepancies among reported data for Np-237 in terms of the $$gamma$$-ray emission probability, experimental method and so on.

Oral presentation

Network graph layout with a hierarchical optimization technique

Miyamura, Hiroko; Wu, H.-Y.*; Takahashi, Shigeo*; Ozahata, Satoshi*; Nakao, Akihiro*

no journal, , 

In recent years, file-sharing applications have been widely used, and demand for analysis of the log data from the file-sharing process has increased. Visualization techniques are effective for the analysis of such log data. In this study, we propose a new network graph visualization technique with new node layout method for analyzing the file-sharing process using geographic information and the network hierarchical optimization. We applied the proposed technique to a log data of a file-sharing application.

Oral presentation

Optimizing P2P network hierarchies for visual analytics

Wu, H.-Y.*; Takahashi, Shigeo*; Miyamura, Hiroko; Ozahata, Satoshi*; Nakao, Akihiro*

no journal, , 

In recent years, file-sharing applications have been widely used, and demand for analysis of the log data from the file-sharing process has increased. Visualization techniques are effective for the analysis of such log data. In this study, we propose a new node layout method for analyzing the file-sharing process using the network hierarchical optimization.

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