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Journal Articles

Evidence for strong correlations at finite temperatures in the dimerized magnet Na$$_{2}$$Cu$$_{2}$$TeO$$_{6}$$

Shangguan, Y.*; Bao, S.*; Dong, Z.-Y.*; Cai, Z.*; Wang, W.*; Huang, Z.*; Ma, Z.*; Liao, J.*; Zhao, X.*; Kajimoto, Ryoichi; et al.

Physical Review B, 104(22), p.224430_1 - 224430_8, 2021/12

Journal Articles

Data-driven derivation of partial differential equations using neural network model

Koyamada, Koji*; Yu, L.*; Kawamura, Takuma; Konishi, Katsumi*

International Journal of Modeling, Simulation, and Scientific Computing, 12(2), p.2140001_1 - 2140001_19, 2021/04

With the improvement of sensors technologies in various fields such as fluid dynamics, meteorology, and space observation, it is an important issue to derive explanatory models using partial differential equations (PDEs) for the big data obtained from them. In this paper, we propose a technique for estimating linear PDEs with higher-order derivatives for spatiotemporally discrete point cloud data. The technique calculates the time and space derivatives from a neural network (NN) trained on the point cloud data, and estimates the derivative term of the PDE using regression analysis techniques. In the experiment, we computed the error of the estimated PDEs for various meta-parameters for the PDEs with exact solutions. As a result, we found that increasing the hierarchy of NNs to match the order of the derivative terms in the exact solution PDEs and adopting L1 regularization with LASSO as the method of regression analysis increased the accuracy of the model.

Journal Articles

Evidence for magnon-phonon coupling in the topological magnet Cu$$_{3}$$TeO$$_{6}$$

Bao, S.*; Cai, Z.*; Si, W.*; Wang, W.*; Wang, X.*; Shangguan, Y.*; Ma, Z.*; Dong, Z.-Y.*; Kajimoto, Ryoichi; Ikeuchi, Kazuhiko*; et al.

Physical Review B, 101(21), p.214419_1 - 214419_8, 2020/06

 Times Cited Count:4 Percentile:68.88(Materials Science, Multidisciplinary)

Journal Articles

Spin dynamics of a magnetic Weyl semimetal Sr$$_{1-x}$$Mn$$_{1-y}$$Sb$$_{2}$$

Cai, Z.*; Bao, S.*; Wang, W.*; Ma, Z.*; Dong, Z.-Y.*; Shangguan, Y.*; Wang, J.*; Ran, K.*; Li, S.*; Kamazawa, Kazuya*; et al.

Physical Review B, 101(13), p.134408_1 - 134408_10, 2020/04

 Times Cited Count:2 Percentile:24.67(Materials Science, Multidisciplinary)

Dirac matters provide a platform for exploring the interplay of their carriers with other quantum phenomena. Sr$$_{1-x}$$Mn$$_{1-y}$$Sb$$_{2}$$ has been proposed to be a magnetic Weyl semimetal and provides an excellent platform to study the coupling between Weyl fermions and magnons. We performed inelastic neutron scattering measurements on single crystals of Sr$$_{1-x}$$Mn$$_{1-y}$$Sb$$_{2}$$, and found The dispersion in the magnetic Mn layer extends up to about 76 meV, while that between the layers has a narrow band width of 6 meV. Despite the coexistence of Weyl fermions and magnons, we find no clear evidence that the magnetic dynamics are influenced by the Weyl fermions in Sr$$_{1-x}$$Mn$$_{1-y}$$Sb$$_{2}$$, possibly because that the Weyl fermions and magnons reside in the Sb and Mn layers separately, and the interlayer coupling is weak due to the quasi-two-dimensional nature of the material.

Journal Articles

Fine structure in the $$alpha$$ decay of $$^{223}$$U

Sun, M. D.*; Liu, Z.*; Huang, T. H.*; Zhang, W. Q.*; Andreyev, A. N.; Ding, B.*; Wang, J. G.*; Liu, X. Y.*; Lu, H. Y.*; Hou, D. S.*; et al.

Physics Letters B, 800, p.135096_1 - 135096_5, 2020/01

 Times Cited Count:6 Percentile:89.19(Astronomy & Astrophysics)

Journal Articles

Liquid-like thermal conduction in intercalated layered crystalline solids

Li, B.; Wang, H.*; Kawakita, Yukinobu; Zhang, Q.*; Feygenson, M.*; Yu, H. L.*; Wu, D.*; Ohara, Koji*; Kikuchi, Tatsuya*; Shibata, Kaoru; et al.

Nature Materials, 17(3), p.226 - 230, 2018/03

 Times Cited Count:71 Percentile:96.98(Chemistry, Physical)

Journal Articles

Origin of dramatic oxygen solute strengthening effect in titanium

Yu, Q.*; Qi, L.*; Tsuru, Tomohito; Traylor, R.*; Rugg, D.*; Morris, J. W. Jr.*; Asta, M.*; Chrzan, D. C.*; Minor, A. M.*

Science, 347(6222), p.635 - 639, 2015/02

 Times Cited Count:146 Percentile:97.59(Multidisciplinary Sciences)

Given that solute atoms interact weakly with the long-range elastic fields of screw dislocations, it has long been accepted that solution hardening is only marginally effective in materials with mobile screw dislocations. This accepted wisdom has recently been questioned by first-principles calculations suggesting that solutes may interact much more strongly with the screw dislocation core. We report here the results of a combined experimental and computational study undertaken to elucidate the profound hardening effect of oxygen in pure hexagonally-close-packed structured $$alpha$$-Ti. High resolution and in situ transmission electron microscopy nanomechanical characterization establish that the strengthening is due to the strong interaction between oxygen and the core of screw dislocations that mainly glide on prismatic planes. First-principles calculations of the screw dislocation core reveal a simple crystallographic source for the oxygen-dislocation interaction that is consistent with experimental observations. The distortion of the interstitial sites at the dislocation core creates a very strong but short-range repulsion for oxygen atoms. These mechanisms effectively pin the dislocation near the oxygen interstitial. These results establish a highly effective mechanism for strengthening by interstitial solutes that, contrary to prior understanding, may be significant in many structural alloys.

Journal Articles

Development of a GEM-TPC for H-dibaryon search experiment at J-PARC

Sako, Hiroyuki; Ahn, J. K.*; Baek, K. H.*; Bassalleck, B.*; Fujioka, H.*; Guo, L.*; Hasegawa, Shoichi; Hicks, K.*; Honda, R.*; Hwang, S. H.*; et al.

Journal of Instrumentation (Internet), 9(4), p.C04009_1 - C04009_10, 2014/04

 Times Cited Count:3 Percentile:18.85(Instruments & Instrumentation)

A TPC has been developed for J-PARC E42 experiment to search for H-dibaryon in ($$K^-$$, $$K^+$$) reaction. An event with 2 $$pi^-$$ and 2 protons decaying from H-dibaryon is searched for inside the TPC. The TPC has octagonal prism shape drift volume with about 50 cm diameter with 55 cm drift length filled with Ar-CH$$_{4}$$ (90:10) gas. At the end of the drift volume, 3-layer GEMs are equipped. In order to analyze momenta of produced particles, the TPC is applied with 1 T dipole magnetic field parallel to the drift electric field with a superconducting Helmholz magnet. In order to maximize the acceptance of H-dibaryon events, a diamond target is installed inside the TPC drift volume, in a cylindrical hole opened from the top to the middle of the drift volume. Since extremely high-rate $$K^-$$ beam is directly injected into the TPC drift volume to the target, a gating grid and GEMs are adopted to suppress positive-ion feedback.

Journal Articles

Diluted ferromagnetic semiconductor Li(Zn,Mn)P with decoupled charge and spin doping

Deng, Z.*; Zhao, K.*; Gu, B.; Han, W.*; Zhu, J. L.*; Wang, X. C.*; Li, X.*; Liu, Q. Q.*; Yu, R. C.*; Goko, Tatsuo*; et al.

Physical Review B, 88(8), p.081203_1 - 081203_5, 2013/08

 Times Cited Count:66 Percentile:92.87(Materials Science, Multidisciplinary)

Journal Articles

Positron annihilation study of 4H-SiC by Ge$$^+$$ implantation and subsequent thermal annealing

Yu, R. S.*; Maekawa, Masaki; Kawasuso, Atsuo; Wang, B. Y.*; Wei, L.*

Nuclear Instruments and Methods in Physics Research B, 270, p.47 - 49, 2012/01

 Times Cited Count:4 Percentile:36.4(Instruments & Instrumentation)

Journal Articles

Simultaneous generation of ions and high-order harmonics from thin conjugated polymer foil irradiated with ultrahigh contrast laser

Choi, I. W.*; Kim, I. J.*; Pae, K. H.*; Nam, K. H.*; Lee, C.-L.*; Yun, H.*; Kim, H. T.*; Lee, S. K.*; Yu, T. J.*; Sung, J. H.*; et al.

Applied Physics Letters, 99(18), p.181501_1 - 181501_3, 2011/11

 Times Cited Count:16 Percentile:59.6(Physics, Applied)

We report the manufacturing of a thin foil target made of conjugated polymer, and the simultaneous observation of laser accelerated ions and second harmonic radiation, when irradiated with ultrahigh-contrast laser pulse at a maximum intensity of 4$$times$$10$$^{19}$$ W/cm$$^{2}$$. Maximum proton energy of 8 MeV is achieved along the target normal direction. Strong second harmonic with over 6% energy ratio compared to fundamental is emitted along the specular direction. Two-dimensional particle-in-cell simulations confirm the simultaneous generation of protons and high-order harmonics, which demonstrates the feasibility of applications requiring particle and radiation sources at once, effectively using the same laser and target.

Journal Articles

Li(Zn,Mn)As as a new generation ferromagnet based on a I-II-V semiconductor

Deng, Z.*; Jin, C. Q.*; Liu, Q. Q.*; Wang, X. C.*; Zhu, J. L.*; Feng, S. M.*; Chen, L. C.*; Yu, R. C.*; Arguello, C.*; Goko, Tatsuo*; et al.

Nature Communications (Internet), 2, p.1425_1 - 1425_5, 2011/08

 Times Cited Count:137 Percentile:93.89(Multidisciplinary Sciences)

In a prototypical ferromagnet (Ga,Mn)As based on a III-V semiconductor, substitution of divalent Mn atoms into trivalent Ga sites leads to severely limited chemical solubility and metastable specimens available only as thin films. The doping of hole carriers via (Ga,Mn) substitution also prohibits electron doping. To overcome these difficulties, Masek et al. theoretically proposed systems based on a I-II-V semiconductor LiZnAs, where isovalent (Zn,Mn) substitution is decoupled from carrier doping with excess/deficient Li concentrations. Here we show successful synthesis of Li$$_{1+y}$$(Zn$$_{1-x}$$Mn$$_x$$)As in bulk materials. We reported that ferromagnetism with a critical temperature of up to 50 K is observed in nominally Li-excess compounds, which have p-type carriers.

Journal Articles

Guiding and confining fast electrons by transient electric and magnetic fields with a plasma inverse cone

Lei, A. L.*; Cao, L. H.*; Yang, X. Q.*; Tanaka, Kazuo*; Kodama, Ryosuke*; He, X. T.*; Mima, Kunioki*; Nakamura, Tatsufumi; Norimatsu, Takayoshi*; Yu, W.*; et al.

Physics of Plasmas, 16(2), p.020702_1 - 020702_4, 2009/02

 Times Cited Count:12 Percentile:46.02(Physics, Fluids & Plasmas)

The fast electron propagation in an inverse cone target is investigated computationally and experimentally. Two-dimensional particle-in-cell simulation shows that fast electrons with substantial numbers are generated at the outer tip of an inverse cone target irradiated by a short intense laser pulse. These electrons are guided and confined to propagate along the inverse cone wall, forming a large surface current. The experiment qualitatively verifies the guiding and confinement of the strong electron current in the wall surface. The large surface current and induced strong field s are of importance for fast ignition related research.

Journal Articles

Efficient production of a collimated MeV proton beam from a Polyimide target driven by an intense femtosecond laser pulse

Nishiuchi, Mamiko; Daido, Hiroyuki; Yogo, Akifumi; Orimo, Satoshi; Ogura, Koichi; Ma, J.-L.; Sagisaka, Akito; Mori, Michiaki; Pirozhkov, A. S.; Kiriyama, Hiromitsu; et al.

Physics of Plasmas, 15(5), p.053104_1 - 053104_10, 2008/05

 Times Cited Count:40 Percentile:84.02(Physics, Fluids & Plasmas)

High-flux energetic protons whose maximum energies are up to 4 MeV are generated by an intense femtosecond Titanium Sapphire laser pulse interacting with a 7.5, 12.5, and 25$$mu$$m thick Polyimide tape targets. The laser pulse energy is 1.7 J, duration is 34 fs, and intensity is 3$$times$$10$$^{19}$$Wcm$$^{-2}$$. The amplified spontaneous emission (ASE) has the intensity contrast ratio of 4$$times$$10$$^{-8}$$. The conversion efficiency from laser energy into proton kinetic energies of $$sim$$3% is achieved, which is comparable or even higher than those achieved in the previous works with nanometer-thick targets and the ultrahigh contrast laser pulses ($$sim$$10$$^{-10}$$).

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:74.53(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

Development of laser driven proton sources and their applications

Daido, Hiroyuki; Sagisaka, Akito; Ogura, Koichi; Orimo, Satoshi; Nishiuchi, Mamiko; Mori, Michiaki; Ma, J.-L.; Pirozhkov, A. S.; Kiriyama, Hiromitsu; Kanazawa, Shuhei; et al.

Proceedings of 7th Pacific Rim Conference on Lasers and Electro-Optics (CLEO-PR 2007) (CD-ROM), p.77 - 79, 2007/00

We are developing a proton accelerator using an intense lasers with a focused intensity of $$>$$ 10$$^{17}$$ W/cm$$^{2}$$. To monitor proton energy spectra as well as plasma parameters at each laser shot, we are using real time detectors. The proton energy of MeV is stably obtained for applications.

Journal Articles

Incident energy and polarization-dependent resonant inelastic X-ray scattering study of La$$_2$$CuO$$_4$$

Lu, L.*; Hancock, J. N.*; Chabot-Couture, G.*; Ishii, Kenji; Vajk, O. P.*; Yu, G.*; Mizuki, Junichiro; Casa, D.*; Gog, T.*; Greven, M.*

Physical Review B, 74(22), p.224509_1 - 224509_9, 2006/12

 Times Cited Count:34 Percentile:79.35(Materials Science, Multidisciplinary)

We present a detailed Cu $$K$$-edge resonant inelastic X-ray scattering (RIXS) study of the Mott insulator La$$_2$$CuO$$_4$$ in the 1-7 eV energy loss range. As initially found for the high-temperature superconductor HgBa$$_2$$CuO$$_{4+delta}$$, the spectra exhibit a multiplet of weakly dispersive electron-hole excitations, which are revealed by utilizing the subtle dependence of the cross section on the incident photon energy. The close similarity between the fine structures for in-plane and out-of-plane polarizations is indicative of the central role played by the 1s core hole in inducing charge excitations within the CuO$$_2$$ planes. On the other hand, we observe a polarization dependence of the spectral weight, and careful analysis reveals two separate features near 2 eV that may be related to different charge-transfer processes. The polarization dependence indicates that the $$4p$$ electrons contribute significantly to the RIXS cross section.

Journal Articles

Large-scale identification and characterization of alternative splicing variants of human gene transcripts using 56 419 completely sequenced and manually annotated full-length cDNAs

Takeda, Junichi*; Suzuki, Yutaka*; Nakao, Mitsuteru*; Barrero, R. A.*; Koyanagi, Kanako*; Jin, L.*; Motono, Chie*; Hata, Hiroko*; Isogai, Takao*; Nagai, Keiichi*; et al.

Nucleic Acids Research, 34(14), p.3917 - 3928, 2006/00

 Times Cited Count:33 Percentile:55.33(Biochemistry & Molecular Biology)

We report the first genome-wide identification and characterization of alternative splicing in human gene transcripts based on analysis of the full-length cDNAs. Applying both manual and computational analyses for 56 419 completely sequenced and precisely annotated full-length cDNAs selected for the H-Invitational human transcriptome annotation meetings, we identified 6877 alternative splicing genes with 18 297 different alternative splicing variants. A total of 37 670 exons were involved in these alternative splicing events. The encoded protein sequences were affected in 6005 of the 6877 genes. Notably, alternative splicing affected protein motifs in 3015 genes, subcellular localizations in 2982 genes and transmembrane domains in 1348 genes. Genome-wide annotations of alternative splicing, relying on full-length cDNAs, should lay firm groundwork for exploring in detail the diversification of protein function which is mediated by the alternative splicing variants.

Journal Articles

Initial boronization of JT-60U tokamak using decaborane

Saido, Masahiro; Ogiwara, Norio; Shimada, Michiya; Arai, Takashi; Hiratsuka, Hajime; ; Shimizu, Masatsugu; Ninomiya, Hiromasa; Nakamura, Hiroo; *; et al.

Japanese Journal of Applied Physics, 32(7), p.3276 - 3281, 1993/07

 Times Cited Count:54 Percentile:90.71(Physics, Applied)

no abstracts in English

Oral presentation

Simultaneous imaging of a test sample with a MeV proton beam and X-ray driven by an intense laser

Orimo, Satoshi; Yogo, Akifumi; Sagisaka, Akito; Ogura, Koichi; Mori, Michiaki; Pirozhkov, A. S.; Li, Z.*; Ma, J.-L.; Daido, Hiroyuki; Nakamura, Shu*; et al.

no journal, , 

Laser drive ion acceleration generated by thin foil irradiation high intensity laser and it is applications. An intense p-pol. laser was irradiated by the 45 degree incident angle on 3$$times$$10$$^{18}$$Wcm$$^{-2}$$ at 5 microns thickness copper tape target. The proton of a maximum of more 2MeV was generated, and a space spread and the propagation characteristic for energy of the were measured using CR39 with a range filter. Moreover, demonstration of simultaneous imaging by the proton beam and X-rays was measured.

Oral presentation

Efficient production of MeV proton beam from a Polyimide target driven by an intense femto-second laser

Nishiuchi, Mamiko; Daido, Hiroyuki; Yogo, Akifumi; Orimo, Satoshi; Ogura, Koichi; Ma, J.-L.; Sagisaka, Akito; Mori, Michiaki; Pirozhkov, A. S.; Kiriyama, Hiromitsu; et al.

no journal, , 

The efficient proton beam whose maximum energy of up to 4 MeV was produced by the 50TW short pulse intensity Ti:Sap laser irradiated on the polyimide target [(C16H6O4N2)n] with the thicknesses of 7.5$$mu$$m, 12.5$$mu$$m, 25$$mu$$m, which is transparent to the 800nm laser. The laser parameters are energy of 1.7J, pulse width of 35fs and the intensity of 3$$times$$10$$^{19}$$Wcm$$^{-2}$$. The contrast of the ASE component is 4$$times$$10$$^{-8}$$. The conversion efficiency from laser energy into the proton kinetic energy is up to $$sim$$3%. This conversion efficiency is comparable or even higher than the results obtained with the same level laser ($$sim$$ J energy) interacts with the nano-meter level ultra thin target. In this paper we discuss on the comparison between our results and other experimental results obtained in other facilities.

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