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Search Results: 1 - 10 of 118755 matches for " T. Ono "
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Electron density and plasma waves in mid-latitude sporadic-E layer observed during the SEEK-2 campaign
M. Wakabayashi ,T. Ono
Annales Geophysicae (ANGEO) , 2005,
Abstract: In the mid-latitude ionospheric region, sporadic-E layers (Es layers) have often been observed, revealing multiple layers. The Es layers observed during the SEEK-2 rocket campaign showed double electron density peaks; namely, there are stable lower peaks and relatively unstable upper peaks. We examined the effects of wind shear and the electric fields on the generation of the multiple layer structure, in comparison with the electron density profile, the neutral wind, and the DC electric field observed by the S310 rocket experiments. The results showed that the neutral wind shear is mainly responsible for the generation of the lower layer, while the DC electric field makes a significant contribution to the formation of the upper layer. The difference between the lower and upper layers was also explained by the enhanced AC electric field observed at about 103–105 km altitude. The external DC electric field intensity is expected to be ~5 mV/m, which is enough to contribute to generate the Es layers in the ionosphere. Keywords. Ionosphere (Electric fields; Ionospheric irregularities, Mid-latitude ionosphere)
Selection of Catalysts through Cellular Reproduction
N. Ono,T. Ikegami
Physics , 2002,
Abstract: It has been pointed out that if an autocatalytic cycle produces primitive membrane chemicals, it can compose a self-maintaining proto cell. Moreover, it is known that a proto cell can divide itself spontaneously as it grows. An unsolved problem is how such a catalytic system can evolve in the pre-cellular environment. Here we examine, as the first step, the evolution of catalysts that have different activity in generating membrane chemicals using a Lattice-Gas-like model. We demonstrated that a self-replicating proto-cell emerges from random initial configuration. We also showed that cells with higher activity of membrane production evolve through cellular selection.
Study of Correlation Coefficient for Breast Tumor Detection in Microwave Tomography  [PDF]
L. Mohamed, N. Ozawa, Y. Ono, T. Kamiya, Y. Kuwahara
Open Journal of Antennas and Propagation (OJAPr) , 2015, DOI: 10.4236/ojapr.2015.34004
Abstract: In microwave tomography, it is necessary to increase the amount of diverse observation data for accurate image reconstruction of the dielectric properties of the imaging area. The multi-polarization method has been proposed as a suitable technique for the acquisition of a variety of observation data. While the effectiveness of employing multi-polarization to reconstruct images has been confirmed, the physical considerations related to image reconstruction have not been investigated. In this paper, a compact-sized imaging sensor using multi-polarization for breast cancer detection is presented. An analysis of the correlation coefficient of the received data of adjacent antennas was performed to interpret the imaging results. Numerical simulation results demonstrated that multi-polarization can reconstruct images better compared to single polarizations owing to its low correlation coefficient and condition number.
Pseudosymmetric bias and correct estimation of Coulomb/confinement energy for unintentional quantum dot in channel of metal-oxide-semiconductor field-effect transistor
K. Ono,T. Tanamoto,T. Ohguro
Physics , 2013, DOI: 10.1063/1.4827817
Abstract: We describe a measurement method that enables the correct estimation of the charging energy of an unintentional quantum dot (QD) in the channel of a metal-oxide-semiconductor field-effect transistor (MOSFET). If the channel has a dominant QD with a large charging energy and an array of stray QDs with much weaker charging, this method eliminates the additional voltage drops due to stray QDs by regarding the stray QDs as series resistors. We apply this method to a short-channel MOSFET and find that the charging energy of the dominant QD can indeed be smaller than the size of the Coulomb diamond.
Scaling Behavior of Level Statistics in Quantum Hall Regime
Y. Ono,T. Ohtsuki,B. Kramer
Physics , 1996, DOI: 10.1143/JPSJ.65.1734
Abstract: The scaling property of level statistics in the quantum Hall regime, i.e. 2D disordered electron systems subject to strong magnetic fields, is analyzed numerically in the light of the random matrix theory. The energy dependences of the effective level repulsion parameter, the two level correlation, the GUE-GOE crossover parameter, and the rigidity (or $\Delta_3$-statistics) of the level distributions are investigated for different system sizes by unfolding the original data and by dividing the unfolded spectrum into small regions. It is shown that the critical exponent of the localization length as a function of energy can be determined through the energy dependence of the level statistics. The analyses are carried out not only for the lowest Landau band (LB) but also for the second lowest LB. Furthermore the effect of finite range of disordered potential is studied. The short-ranged potential case in the second lowest LB is found to be pathological as in other studies of critical behavior, and it is confirmed that this pathological behavior is improved in the case of disordered potential with finite ranges.
Current-driven domain wall motion in magnetic wires with asymmetric notches
A. Himeno,S. Kasai,T. Ono
Physics , 2005, DOI: 10.1063/1.2140884
Abstract: Current-driven domain wall (DW) motion in magnetic wires with asymmetric notches was investigated by means of magnetic force microscopy. It was found that the critical current density necessary for the current-driven DW motion depended on the propagation direction of the DW. The DW moved more easily in the direction along which the slope of the asymmetric notch was less inclined.
Systematic evolution of the magnetotransport properties of Bi_{2}Sr_{2-x}La_{x}CuO_{6} in a wide doping range
Yoichi Ando,T. Murayama,S. Ono
Physics , 2000, DOI: 10.1016/S0921-4534(00)01363-0
Abstract: Recently we have succeeded in growing a series of high-quality Bi_{2}Sr_{2-x}La_{x}CuO_{6} crystals in a wide range of carrier concentrations. The data of \rho_{ab}(T) and R_H(T) of those crystals show behaviors that are considered to be "canonical" to the cuprates. The optimum zero-resistance T_c has been raised to as high as 38 K, which is almost equal to the optimum T_c of La_{2-x}Sr_{x}CuO_{4}.
Systematic Evolution of the Magnetotransport Properties of Bi_{2}Sr_{2-x}La_{x}CuO_{6} with Carrier Concentration
Yoichi Ando,T. Murayama,S. Ono
Physics , 1999,
Abstract: We report that it is possible to obtain a series of high-quality crystals of La-doped Bi-2201, of which the transport properties have been believed to be "dirtier" than those of other cuprates. In our crystals, the normal-state transport properties display behaviors which are in good accord with other cuprates; for example, in the underdoped region the in-plane resistivity \rho_{ab} shows the pseudogap feature and in the overdoped region the T dependence of \rho_{ab} changes to T^n with n > 1. The characteristic temperatures of the pseudogap deduced from the resistivity and the Hall coefficient data are presented.
Even-Odd Oscillation in Conductance of Single-Row Sodium Nanowire
Y. Egami,T. Ono,K. Hirose
Physics , 2004, DOI: 10.1103/PhysRevB.72.125318
Abstract: We present a first-principles calculation of the electronic conduction properties of single-row sodium nanowires suspended between semi-infinite electrodes. The conductance of the nanowire is ~1 G0 (=2e^2/h) and oscillates with a two-atom period as the number of the atoms within the nanowire varies. Moreover, we observed bunches of high electron density with a two atom-lengths in the channel density distribution. The relation between the period of the conductance oscillation and the length of bunches are examined by using simplified models and is found to be largely affected by the characteristics of the infinite wire.
Short timescale behavior of colliding heavy nuclei at intermediate energies
S. Hudan,R. T. deSouza,A. Ono
Physics , 2005, DOI: 10.1103/PhysRevC.73.054602
Abstract: An Antisymmetrized Molecular Dynamics model is used to explore the collision of $^{114}$Cd projectiles with $^{92}$Mo target nuclei at E/A=50 MeV over a broad range in impact parameter. The atomic number (Z), velocity, and emission pattern of the reaction products are examined as a function of the impact parameter and the cluster recognition time. The non-central collisions are found to be essentially binary in character resulting in the formation of an excited projectile-like fragment (PLF$^*$) and target-like fragment (TLF$^*$). The decay of these fragments occurs on a short timescale, 100$\le$t$\le$300 fm/c. The average excitation energy deduced for the PLF$^*$ and TLF$^*$ `saturates for mid-central collisions, 3.5$\le$b$\le$6 fm, with its magnitude depending on the cluster recognition time. For short cluster recognition times (t=150 fm/c), an average excitation energy as high as $\approx$6 MeV is predicted. Short timescale emission leads to a loss of initial correlations and results in features such as an anisotropic emission pattern of both IMFs and alpha particles emitted from the PLF$^*$ and TLF$^*$ in peripheral collisions.
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