Influence of current on field-driven domain wall motion in permalloy nanowires from time resolved measurements of anisotropic magnetoresistance

The motion of magnetic domain walls in permalloy nanowires is investigated by real-time resistance measurements. The domain wall velocity is measured as a function of the magnetic field in the presence of a current flowing through the nanowire. We show that the current can significantly increase or decrease the domain wall velocity, depending on its direction. These results are understood within a one-dimensional model of the domain wall dynamics which includes the spin transfer torque.     

Exact diagonalization studies on two-band minimal model for iron-based superconductors

In order to explore a superconducting mechanism on iron-based superconductors, we numerically study a two-band minimal model considering two degenerate d_xz and d_yz orbitals on Fe atom. We perform exact diagonalization on a two-band and two-leg square ladder totally composed of 10 lattice sites, which is computationally equivalent to 4-leg 20-sites square-Hubbard-ladder. Consequently, we find that a robust pairing occurs in a wide parameter range when the intra-orbital repulsive interaction becomes smaller than the inter-orbital one. Moreover, the obtained binding energy can grow into much larger value than that obtained in the single band Hubbard model depending on the parameter range.     

Measurement of B(0)(d)-B_(0)(d) mixing rate from the time evolution of dilepton events at the upsilon(4S)

We report a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on the time evolution of dilepton yields in Upsilon(4S) decays. The measurement is based on a 5.9 fb(-1) data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing Deltam(d) as a free parameter. Using both muons and electrons, we obtain Deltam(d) = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This is the first determination of Deltam(d) from time evolution measurements at the Upsilon(4S). We also place limits on possible CPT violations.     

Tissue gadolinium deposition in renally impaired rats exposed to different gadolinium-based MRI contrast agents: Evaluation with inductively coupled plasma mass spectrometry (ICP-MS)

ObjectivesTo quantify tissue gadolinium (Gd) deposition in renally impaired rats exposed to Gd-EOB-DTPA and other Gd-based MRI contrast agents by means of inductively coupled plasma mass spectrometry (ICP-MS), and to compare the differences in distribution among major organs as possible triggers for nephrogenic systemic fibrosis (NSF).MethodsA total of 15 renally impaired rats were injected with Gd-EOB-DTPA, Gd-DTPA-BMA and Gd-HP-DO3A. Gd contents of skin, liver, kidney, lung, heart, spleen, diaphragm and femoral muscle were measured by inductively coupled plasma mass spectrometry (ICP-MS). Histological assessment was also conducted.ResultsTissue Gd deposition in all organs was significantly higher (P = 0.005 ~ 0.009) in the Gd-DTPA-BMA group than in the Gd-HP-DO3A and Gd-EOB-DTPA groups. In the Gd-DTPA-BMA group, Gd was predominantly deposited in kidney (1306 ± 605.7 μg/g), followed by skin, liver, lung, spleen, femoral muscle, diaphragm and heart. Comparing Gd-HP-DO3A and Gd-EOB-DTPA groups, Gd depositions in the kidney, liver and lung were significantly lower (P = 0.009 ~ 0.011) in the Gd-EOB-DTPA group than in the Gd-HP-DO3A group although no significant differences were seen for any other organs.ConclusionsGd-EOB-DTPA is a stable and safe Gd-based contrast agent (GBCA) showing lower Gd deposition in major organs in renally impaired rats, compared with other GBCAs. This fact suggests that the risk of NSF onset would be low in the use of Gd-EOB-DTPA.     

Large Time Asymptotics for the Kadomtsev–Petviashvili Equation

We study the large time asymptotic behavior of solutions to the Kadomtsev–Petviashvili equations $$\left\{\begin{array}{ll} u_{t} + u_{xxx} + \sigma \partial_{x}^{-1}u_{yy} = -\partial_{x}u^{2}, \quad \quad (x, y) \in {\bf R}^{2}, t \in {\bf R},\\ u(0, x, y) = u_{0}( x, y), \, \quad \quad \qquad \qquad (x, y) \in {\bf R}^{2},\end{array}\right.$$ where σ = ±1 and \({\partial_{x}^{-1} = \int_{-\infty}^{x}dx^{\prime} }\) . We prove that the large time asymptotics of the derivative u _x of the solution has a quasilinear character.     

Electrical transport in electron beam irradiated polyacetylene

Electrical conductivity of non-doped (CH)_x decreases a little and its activation energy increases a little by the electron beam irradiation. The increase of the electrical conductivity of the irradiated (CH)_x by I₂ doping is not so remarkable compared with that of non-irradiated (CH)_x. The conductivity of heavily irradiated (CH)_x is very low even after halogen dopings.On the other hand, the effect of the electron beam irradiation on the conductivity of previously I₂ doped (CH)_x is much less compared with that doped after the electron beam irradiation. These results are explained tentatively by the role of I₂ molecules in the initial stage of radiolysis and the suppression of the cross-linking.     

Polymeric saturable-absorber mirror for passive Q-switching of a laser-diode-pumped Nd3+:YVO4 microchip laser

A polymeric multilayered mirror doped with a saturable dye worked as a passive Q-switch of a laser-diode-pumped Nd(3+):YVO4 microchip laser. The multilayered mirror consisted of alternately spin-coated layers of polyvinylcarbazole (PVK) and cellulose acetate on a glass substrate. A dye of bis-(dimethylaminodithiobenzil)-nickel was doped in one of the layers of PVK, providing the repetitively Q-switched pulses. The pulse width and repetition rate were 4 ns and 68 kHz, respectively, for a laser-cavity length of 5 mm, and the average and the peak power were 40 mW and 156 W, respectively, for the highest pump power of 435 mW. The dependence of the Q-switched characteristics on the pump power and on the concentration of the doped dye is described.