Theory of AC Anomalous Hall Conductivity in d-electron systems

To elucidate the intrinsic nature of anomalous Hall effect (AHE) in $d$-electron systems, we study the AC anomalous Hall conductivity (AHC) in a tight-binding model with ($d_{xz},d_{yz}$)-orbitals. We drive a general expression for the AC AHC $\sigma_{xy}(\omega)$, which is valid for finite quasiparticle damping rate $\gamma$=$\hbar/2\tau$, and find that the AC AHC is strongly dependent on $\gamma$. When $\gamma=+0$, the AC AHC shows a spiky peak at finite energy $\Delta$ that originates from the interband particle-hole excitation, where $\Delta$ represents the minimum band-splitting measured from the Fermi level. In contrast, we find that this spiky peak is quickly suppressed when $\gamma$ is finite. By using a realistic value of $\gamma(\omega)$ at $\omega=\Delta/2$ in $d$-electron systems, the spiky peak is considerably suppressed. In the present model, the obtained results also represents the AC spin Hall conductivity in a paramagnetic state.Comment: 13pages, 9 figure

Anisotropic intrinsic anomalous Hall effect in ordered 3dPt alloys

By performing first principles calculations we investigate the intrinsic anomalous Hall conductivity (AHC) and its anisotropy in ordered L1o FePt, CoPt and NiPt ferromagnets, and their intermediate alloys. We demonstrate that the AHC in this family of compounds depends strongly on the direction of the magnetization in the crystal. We predict that such pronounced orientational dependence in combination with the general decreasing trend of the AHC when going from FePt to NiPt leads to a sign change of the AHC upon rotating the magnetization direction in the crystal of CoPt alloy. We also suggest that for a range of concentration x in Co(x)Ni(1-x)Pt alloy it is possible to achieve a complete quenching of the anomalous Hall current for a certain direction of the magnetization in the crystal. By analyzing the spin-resolved AHC in 3dPt alloys we endeavor to relate the overall trend of the AHC in these compounds to the changes in their densities of d-states around the Fermi energy upon varying the atomic number. Moreover, we show the generality of the phenomenon of anisotropic anomalous Hall effect by demonstrating its occurrence within the three-band tight-binding model.Comment: 10 page

Correlation of high energy muons with primary composition in extensive air shower

An experimental investigation of high energy muons above 200 GeV in extensive air showers has been made for studying high energy interaction and primary composition of cosmic rays of energies in the range 10 to the 14th power approx. 10 to the 15th power eV. The muon energies are estimated from the burst sizes initiated by the muons in the rock, which are measured by four layers of proportional counters, each of area 5 x 2.6 sq m, placed at 30 m.w.e. deep, Funasaka tunnel vertically below the air shower array. These results are compared with Monte Carlo simulations based on the scaling model and the fireball model for two primary compositions, all proton and mixed

Proportional drift tubes for large area muon detectors

A proportional drift chamber which consists of eight rectangular drift tubes with cross section of 10 cm x 5 cm, a sense wire of 100 micron phi gold-plated tungsten wire and the length of 6 m, was tested using cosmic ray muons. Spatial resolution (rms) is between 0.5 and 1 mm over drift space of 50 mm, depending on incident angle and distance from sense wire

Chromium at High Pressures: Weak Coupling and Strong Fluctuations in an Itinerant Antiferromagnet

The spin- and charge-density-wave order parameters of the itinerant antiferromagnet chromium are measured directly with non-resonant x-ray diffraction as the system is driven towards its quantum critical point with high pressure using a diamond anvil cell. The exponential decrease of the spin and charge diffraction intensities with pressure confirms the harmonic scaling of spin and charge, while the evolution of the incommensurate ordering vector provides important insight into the difference between pressure and chemical doping as means of driving quantum phase transitions. Measurement of the charge density wave over more than two orders of magnitude of diffraction intensity provides the clearest demonstration to date of a weakly-coupled, BCS-like ground state. Evidence for the coexistence of this weakly-coupled ground state with high-energy excitations and pseudogap formation above the ordering temperature in chromium, the charge-ordered perovskite manganites, and the blue bronzes, among other such systems, raises fundamental questions about the distinctions between weak and strong coupling.Comment: 11 pages, 9 figures (8 in color

Effects of non-frozen cold storage on the growth, organogenesis and secondary metabolism of callus cultures

Abstract. Callus tissues derived from chilling-tolerant herbaceous plant, Atractylodes lancea, Atropa belladonna, Bupleurum falcatum, Dioscorea tokoro, Lithospermum erythrorhizon and Phytolacca americana could be cold-stored at 4°C for three months or more, whereas those from chilling-sensitive herbaceous plants such as Datura innoxia and Perilla frutescens vat. crispa and a deciduous tree, Mallotus ]aponicus, could not survive after cold storage for two to three months. Tobacco callus cultures could be stored at 4°C for two or four months depending on a callus strain. The effect of cold storage on secondary metabolite production varied. Nicotine and betalain production suffered from cold storage of tobacco and Phytolacca americana callus cultures, respectively. However, production of anthocyanin in cultures of Mallotus ]aponicus and Bupleurum falcatum and shikonin derivatives in Lithospermum erythrorhizon callus was affected very little. Root-forming ability was retained for more than one year in cold-stored callus tissues of Bupleurum falcatum, while the control callus tissues maintained at 25°C completely lost the organogenetic ability six months after the first subculture

A new method to establish the rational extent of hepatic resection for advanced gallbladder cancer using dye injection through the cystic artery

BackgroundHepatic resection has been indicated to eliminate cancer at the surgical margin in cases of advanced gallbladder carcinoma, but there is considerable controversy about the reasonable extent of liver resection. A new on‐table dye injection technique has been introduced to determine the venous drainage of the gallbladder and ascertain the amount of liver to remove.MethodsIn four hepatic resections for pT2 gallbladder cancer, indocyanine green solution (25 mg/20 ml) was injected over a period of 30 seconds through the cystic artery. The stained area of the liver surface was completely resected, maintaining a margin of at least 2 cm from the gallbladder.ResultsThe entire serosal surface of the gallbladder takes on a light green stain immediately after dye injection, and then the liver surface around the gallbladder gradually becomes stained with a clear demarcation line. The distance between the demarcation line and the gallbladder ranged from 1.0 to 5.0 cm. The extent of the stained area differed from one individual to another. Histopathological examination of resected liver specimens revealed that one of the four resected livers had micrometastasis in the portal area 27 mm from the gallbladder wall and there were no cancer cells at the surgical margins. No recurrence has been seen in any of our 4 patients at 16–26 months after operation.DiscussionThe dye injection method is useful in determining the appropriate extent of hepatic resection for advanced gallbladder cancer, as it is possible to determine the necessary and sufficient amount of liver parenchyma that should be removed according to the perfusion area of the cystic veins in each individual patient