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Hokkaido University Collection of Scholarly and Academic Papers (135.521 recursos)

HUSCAP (Hokkaido University Collection of Scholarly and Academic Papers) contains peer-reviewed journal articles, proceedings, educational resources and any kind of scholarly works of Hokkaido University.

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Mostrando recursos 1 - 20 de 2.165

  1. Stellar population and dust extinction in an ultraluminous infrared galaxy at z=1.135

    Kawara, K.; Oyabu, S.; Matsuoka, Y.; Yoshii, Y.; Minezaki, T.; Sameshima, H.; Asami, N.; Ienaka, N.; Kozasa, T.
    We present the detailed optical to far-infrared (far-IR) observations of SST J1604+4304, an ultraluminous IR galaxy at z = 1.135. Analysing the stellar absorption lines, namely, the Ca II H & K and Balmer H lines in the optical spectrum, we derive the upper limits of an age for the stellar population. Given this constraint, the minimum χ2 method is used to fit the stellar population models to the observed spectral energy distribution from 0.44 to 5.8 μm. We find the following properties. The stellar population has an age 40-200 Myr with a metallicity 2.5 Z⊙. The starlight is reddened...

  2. Singularities of flat extensions from generic surfaces with boundaries

    Ishikawa, Goo
    We solve the problem on flat extensions of a generic surface with boundary in Euclidean 3-space, relating it to the singularity theory of the envelope generated by the boundary. We give related results on Legendre surfaces with boundaries via projective duality and observe the duality on boundary singularities. Moreover we give formulae related to remote singularities of the boundary-envelope.

  3. Liquid crystalline phase in ethanol suspension of anisometric 4-cyano-4-n-hexylbiphenyl microcrystals : Witnessed by dielectric spectroscopy

    Chen, Zhen; Nozaki, Ryusuke
    The suspensions of 4-cyano-4-n-hexylbiphenyl (6CB) anisometric microcrystal were obtained by quenching homogeneous 6CB/ethanol mixtures with different 6CB concentrations. Such suspensions were strongly suggested from the differential scanning calorimetry examinations and the image observations of the samples during the quench and heating processes. The crystallization process for the mixtures with higher 6CB concentration looked like the isotropic-nematic phase transition of bulk liquid crystal. Dielectric measurement was carried out on the mixtures during the heating process after quench. Distinct dielectric relaxation was observed in the frequency range between kHz and 100 kHz, which exhibited obvious dependence on temperature and 6CB concentration. Curve...

  4. Critical phase of bond percolation on growing networks

    Hasegawa, Takehisa; Nemoto, Koji
    The critical phase of bond percolation on the random growing tree is examined. It is shown that the root cluster grows with the system size N as Nψ and the mean number of clusters with size s per node follows a power function ns ∝ s(-τ) in the whole range of open bond probability p. The exponent τ and the fractal exponent ψ are also derived as a function of p and the degree exponent γ and are found to satisfy the scaling relation τ=1 + ψ^[-1]. Numerical results with several network sizes are quite well fitted by a finite-size...

  5. Exact results on the two-particle Green’s function of a Bose-Einstein condensate

    Kita, Takafumi

  6. Identification of Silicate and Carbonaceous Presolar Grains in the type 3 Enstatite Chondrites

    Ebata, Shingo; Yurimoto, Hisayoshi
    We surveyed presolar grains in primitive enstatite chondrites by isotopography using the HokuDai isotope microscope system. The mineral identification has been conducted by X-ray analysis with scanning electron microscopy. The chemical compositions are determined for eight silicate and ten carbonaceous presolar grains. Presolar grains of pyroxene compositions are dominant in the enstatite chondrites. This suggests that presolar silicates of enstatite composition were selectively survived in the enstatite chondrite parent body or the enstatite chondrite formation area in the solar nebula.

  7. Scattering theory for the Dirac equation of Hartree type in 2+1 dimensions

    Machihara, Shuji; Tsutaya, Kimitoshi
    Consider a scattering problem for the Dirac equation with a nonlocal term including the Hartree type in two dimensions. We show the existence of scattering operators for small data in the subcritical and critical Sobolev spaces.

  8. Dynamics and structure of hydrogen-bonding glass formers : Comparison between hexanetriol and sugar alcohols based on dielectric relaxation

    Nakanishi, Masahiro; Nozaki, Ryusuke
    Broadband dielectric spectra of supercooled 1,2,6-hexanetriol are presented in order to reveal physical picture behind a glass transition of polyhydric alcohols. It has been reported so far that temperature dependences of α relaxation time for sugar alcohols exhibit systematic trend against number of carbon atoms or OH groups per molecule. However, because each molecule is composed of equal number of carbon atoms and OH groups in the case of the reported sugar alcohols, the more dominant parameter to govern the α relaxation dynamics has not been discussed. By using a chemical structure of the hexanetriol composed of the deferent number...

  9. Antiferromagnetic Fluctuations in the Organic Superconductor κ-(BEDT-TTF)2Cu(NCS)2 under Pressure

    Itaya, Megumi; Eto, Yoshihiro; Kawamoto, Atsushi; Taniguchi, Hiromi
    We measured the C-13-NMR spectrum and T-1 of the quasi-two-dimensional organic superconductor kappa-(BEDT-TTF)(2)Cu(NCS)(2) under pressure. This material was thought to show a relationship between T-c and the effective cyclotron mass m(c)(*), obtained from the Shubnikov-de Haas (SdH) effect. We found that kappa-(BEDT-TTF)(2)Cu(NCS)(2) behaved as a Fermi liquid at low temperature under all pressures, and antiferromagnetic fluctuations were expected. The pressure dependence of the Korringa factor is similar to that of the effective cyclotron mass m(c)(*), suggesting that antiferromagnetic fluctuations contribute to the superconductivity of this material. We also found that, under pressure, T-* was shifted to 150 K, the temperature...

  10. Antiferromagnetic phase in β'-(BEDT-TTF)2ICl2 under pressure as seen via 13C NMR

    Eto, Yoshihiro; Kawamoto, Atsushi
    We assessed carbon-13 nuclear magnetic resonance (13C NMR) measurements of the layered organic salt β'-(BEDT-TTF)2ICl2, which exhibits antiferromagnetic transition at ambient pressure and 22 K and superconductive transition at 8.2 GPa and 14.2 K (the highest known superconductive transition temperature among organic superconductors). By analyzing the 13C NMR spectrum with the tensor, we determined the antiferromagnetic moment of this salt to be μB per dimer at ambient pressure, strongly indicating that this salt is a dimer Mott insulator. From NMR measurements under pressure, we found that the structure of the antiferromagnetic phase changed at 0.6 GPa. The moment of this...

  11. An inverse problem for the one-dimensional wave equation in multilayer media

    Nagayasu, Sei
    We consider half-line media which consist of many kinds of substances.We assume that the waves through this media are described by the one-dimensional wave equation. We can directly observe the data near the boundary point of the half-line, but we cannot directly observe the data of things away from the boundary point. In this situation, we try to identify these unknown things by creating an artificial explosion and observing on the boundary point the waves generated by the explosion. In the previous works related to this problem, only the speeds of the waves were treated, but we also take into...

  12. Microtubule bundle formation driven by ATP : the effect of concentrations of kinesin, streptavidin and microtubules

    Kawamura, Ryuzo; Kakugo, Akira; Osada, Yoshihito; Gong, Jian Ping
    Recently, a method was established for the formation of microtubule (MT) assemblies by an active self-organization (AcSO) process, in which MTs were crosslinked during sliding motion on a kinesin-coated surface, and this was coupled with adenosine triphosphate (ATP) hydrolysis. Streptavidin (ST) was the glue used to crosslink biotin-labeled MTs. Although most of the MT assemblies were in the bundle form, they varied in size, shape and motility, depending on the initial conditions used. In this paper, we systematically examined the effects of the concentrations of kinesin, ST and MT on the formation of MT bundles under the initial conditions of...

  13. Origin of Presolar Grains : Formation of TiC Core-Graphitic Spherules in Carbon-rich AGB Stars

    Chigai, Takeshi; Yamamoto, Tetsuo; Kozasa, Takashi

  14. Magnetic properties of quadruple perovskites Ba4LnRu3O12 (Ln=La, Nd, Sm-Gd, Dy-Lu)

    Shimoda, Yuki; Doi, Yoshihiro; Wakeshima, Makoto; Hinatsu, Yukio
    Quadruple perovskites Ba4LnRu3O12 (Ln=La, Nd, Sm-Gd, Dy-Lu) were prepared and their magnetic properties were investigated. They adopt the 12L-perovskite-type structure consisting of Ru3O12 trimers and LnO6 octahedra. All of these compounds show an antiferromagnetic transition at 2.5-30 K. For Ba4NdRu3O12, ferrimagnetic ordering has been observed at 11.5 K. The observed magnetic transition is due to the magnetic behavior of the Ru^[4.33+]3O12 trimer with S=1/2. Magnetic properties of Ba4LnRu3O12 were compared with those of triple perovskites Ba3LnRu2O9 and double perovskites Ba2LnRuO6.

  15. Changes in the plasma levels of insulin-like growth factor-I from the onset of spawning migration through upstream migration in chum salmon

    Onuma, Takeshi A.; Makino, Keita; Katsumata, Hiroshi; Beckman, Brian R.; Ban, Masatoshi; Ando, Hironori; Fukuwaka, Masa-aki; Azumaya, Tomonori; Swanson, Penny; Urano, Akihisa
    An increase in activity of the pituitary-gonadal axis (PG-axis) and gonadal development are essential for the onset of spawning migration of chum salmon from the Bering Sea. In the Bering Sea, fish with larger body sizes initiated gonadal development and commenced spawning migration to the natal river by the end of summer. We thus hypothesized that insulin-like growth factor-I (IGF-I), a somatotropic signal that interacts with the PG-axis, can be one of such factors responsible for the onset of migration, and examined changes in plasma levels and hepatic expression of IGF-I gene in oceanic and homing chum salmon in 2001,...

  16. Time-variable ice loss in Asian high mountains from satellite gravimetry

    Matsuo, Koji; Heki, Kosuke
    Substantial amount of glacial ice is considered to be melting in the Asian high mountains. Gravimetry by GRACE satellite during 2003-2009 suggests the average ice loss rate in this region of 47 ± 12 Gigaton (Gt) yr^[-1], equivalent to ~0.13 ± 0.04 mm yr^[-1] sea level rise. This is twice as fast as the average rate over ~40 years before the studied period, and agrees with the global tendency of accelerating glacial loss. Such ice loss rate varies both in time and space; mass loss in Himalaya is slightly decelerating while those in northwestern glaciers show clear acceleration. Uncertainty still...

  17. Evidence for exchange interaction between donor and acceptor layers in β'-(BEDT-TTF)(TCNQ)

    Eto, Yoshihiro; Kawamoto, Atsushi; Matsunaga, Noriaki; Nomura, Kazushige; Yamamoto, Kaoru; Yakushi, Kyuya
    We assessed the infrared-absorption spectra and 13C-NMR measurements in a layered organic salt, β'-(BEDT-TTF)(TCNQ), which exhibits antiferromagnetic transitions at 20 and 3 K. The former originates from the spin in the bis-(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) layers, while the latter originates from the localized spin in the tetracyanoquinodimethane (TCNQ) layers. Using infrared-absorption spectroscopy, we estimated the degree of charge transfer, ρ, between BEDT-TTF and TCNQ as 0.5. Using 13C-NMR spectroscopy, we observed an exchange field at the BEDT-TTF site, which is produced by the localized spins of TCNQ dimers. Using the obtained value of ρ and the molecular arrangement of β'-(BEDT-TTF)(TCNQ), which is...

  18. Two-mode long-distance propagation of coseismic ionosphere disturbances

    Astafyeva, Elvira; Heki, Kosuke; Kiryushkin, Vladislav; Afraimovich, Edward; Shalimov, Sergey
    Using GPS total electron content (TEC) measurements, we analyzed ionosphere response to the great Kurile earthquake of 4 October 1994. High spatial resolution of the Japanese dense array of GPS receivers (GEONET) provided us the unique opportunity to observe the evolution of coseismic ionospheric disturbances (CID) which propagated for more than 1800 km away from the epicenter. Plotting a travel-time diagram for the CID and using an "array processing" technique within the approximation of a spherical CID wave front, we observed a phenomenon of CID separation into two modes and we found that characteristics of the CID depend on the...

  19. Interplay between magnetism and conductivity in the one-dimensional organic conductor TPP[Fe(Pc)(CN)2]2

    Kimata, M.; Takahide, Y.; Harada, A.; Satsukawa, H.; Hazama, K.; Terashima, T.; Uji, S.; Naito, T.; Inabe, T.
    The strongly nonlinear current-voltage (I-V) characteristics and the large negative magnetoresistance (MR) are observed at low temperatures in the one-dimensional organic conductor TPP[Fe(Pc)(CN)2]2. The nonlinear I-V curves are interpreted as the transport of the electrons and holes excited from the charge ordered state on the Fe(Pc)(CN)2 chains, whose energy gap strongly depends on electric fields. The negative MR is enhanced as temperature decreases, and the resistance steeply changes over four orders of magnitude around 15 T at 1.5 K. This decrease is associated with a magnetic torque anomaly, and the energy gap is rapidly reduced around 15 T. The detailed...

  20. Ferromagnetic Ising spin systems on the growing random tree

    Hasegawa, Takehisa; Nemoto, Koji
    We analyze the ferromagnetic Ising model on a scale-free tree; the growing random tree model with the linear attachment kernel A_k=k+α. We derive an estimate of the divergent temperature T_s below which the zero-field susceptibility of the system diverges. Our result shows that T_s is related to α as tanh(J/T_s)=α/[2(α+1)], where J is the ferromagnetic interaction. An analysis of exactly solvable limit for the model and numerical calculation supports the validity of this estimate.

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