Half-integer contributions to the quantum Hall conductivity from single Dirac cones

While the quantum Hall effect in graphene has been regarded as a realization of the anomaly associated with the massless Dirac particle carrying half the usual topological integer, this is hidden due to the doubling of the Dirac cones. In order to confirm the half-integer contribution from each Dirac cone, here we theoretically consider a lattice model in which the relative energy between the two Dirac points is systematically shifted. With an explicit calculation of the topological (Chern) number, we have demonstrated that each Dirac cone does indeed contribute to the Hall conductivity as the half odd integer series (... -3/2, -1/2, 1/2, 3/2, ...) when the Fermi energy traverses the (shifted sets of) Landau levels. The picture is also endorsed, via the bulk-edge correspondence, from the edge mode spectrum for the present model.Comment: 4 pages, 4 figure

Spectrum of the Velocity Distribution Function in the Slab Ion Temperature Gradient Driven Turbulence

A spectral analysis of the velocity distribution function in the slab ion temperature gradient (ITG) driven turbulence is done by using high-resolution Eulerian kinetic simulation results. It is clarified how the entropy variable associated with the fine-scale structure of the distribution function is produced by the turbulent heat transport in the presence of the temperature gradient, transferred from macro to microscales in the velocity space through phase- mixing processes, and dissipated by collisions. An interesting analogy between the entropy spectrum in the ITG turbulence and the spectrum of a passive scalar quantity in a turbulent fluid is pointed out. The entropy spectral function is analytically derived and confirmed by the simulation result. It is shown that the entropy spectrum obeys a power law in the range that is free from instability sources and collisional dissipation

Plasma Turbulent Transport and Fine-Scale Structures of Phase Space Distribution Function

Recent results from kinetic simulations of steady and quasisteady states of the ion temperature gradient (ITG) driven turbulence are reviewed in focus on the fine-scale structures of the phase space distribution function associated with the anomalous transport. Importance of proper treatment for the fine structures in numerical simulations of the collisionless ITG turbulence is emphasized by a parameter survey for the velocity space resolution. Preliminary results of the flux tube simulation of the toroidal ITG mode are also given for the linear benchmark test and the collisionless damping in a tokamak configuration

Glutathione metabolism and glucose 6-phosphate dehydrogenase activity in experimental liver injury.

Increased activities of liver glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (6PGD, EC 1.1.1.44) in the pentose phosphate cycle were accompanied with a depletion of reduced glutathione (GSH) following an intragastric administration of carbon tetrachloride (CCl4) to rats. Oxidized glutathione (GSSG) also decreased remarkably, keeping the GSSG: GSH ratio constant. No significant alteration of glutathione reductase (EC 1.6.4.2.), glutathione peroxidase (EC 1.11.1.9) and malic enzyme (EC 1.1.1.40) activities in the supernatant and gamma-glutamyl transpeptidase (gamma-GTP, EC 2.3.2.2) activity in the homogenate of the injured liver were observed. Furthermore, no marked difference in the GSH-synthesizing activity was found between control and CCl4-intoxicated liver. An intraperitoneal injection of GSH produced a significant increase in liver GSH content in control rats but not in CCl4-treated rats; G6PD activity was not affected. Intraperitoneal injections of diethylmaleate resulted in continuously diminished levels of liver GSH without any alteration of liver G6PD activity. In vitro disappearance of GSH added to the liver homogenate from CCl4-treated rats occurred enzymatically and could not be prevented by the addition of a NADPH-generating system. The results suggest that increased G6PD activity in CCl4-injured liver does not play an important role in the maintenance of glutathione in the reduced form and that the decreased GSH content in the injured liver might be caused by enhanced GSH catabolism not due to gamma-GTP.</p

Kinetic simulation of a quasisteady state in collisionless ion temperature gradient driven turbulence

Existence of a quasisteady state with a mean transport flux in the collisionless ion temperature gradient driven turbulence has been confirmed by means of a direct numerical simulation of a basic kinetic equation for the perturbed ion velocity distribution function deltaf. The phase mixing generates fine-scale fluctuations of deltaf and leads to continuous growth of high-order moments which balances the transport flux. The phase relation between the temperature and the parallel heat flux is also examined and compared with a fluid closure model

Collisionless damping of zonal flows in helical systems

Collisionless time evolution of zonal flows in helical systems is investigated. An analytical expression describing the collisionless response of the zonal-flow potential to the initial potential and a given turbulence source is derived from the gyrokinetic equations combined with the quasineutrality condition. The dispersion relation for the geodesic acoustic mode (GAM) in helical systems is derived from the short-time response kernel for the zonal-flow potential. It is found that helical ripples in the magnetic-field strength as well as finite orbit widths of passing ions enhance the GAM damping. The radial drift motions of particles trapped in helical ripples cause the residual zonal-flow level in the collisionless long-time limit to be lower for longer radial wavelengths and deeper helical ripples. On the other hand, a high-level zonal-flow response, which is not affected by helical-ripple-trapped particles, can be maintained for a longer time by reducing their radial drift velocity. This implies a possibility that helical configurations optimized for reducing neoclassical ripple transport can simultaneously enhance zonal flows which lower anomalous transport. The validity of our analytical results is verified by gyrokinetic Vlasov simulation

An approach to nutritional therapy of hepatic encephalopathy by normalization of deranged amino acid patterns in serum

A mixture with essential and nonessential amino acids high in branched chain amino acids and low in aromatic amino acids (Fischer solution), and another synthetic mixture of branched chain amino acids containing 3 amino acids associated with the urea cycle (Hep-OU) were infused to control subjects and patients with severe hepatic disease. Alterations in serum aminograms, blood ammonia levels and electroencephalograms following the infusion were studied and compared with those obtained by a commercially available amino acid mixture. Short-term or continuous infusion of a commercially available amino acid solution to cirrhotic patients caused an increase in methionine, phenylalanine and tyrosine and a decrease in branched chain amino acids. These post-infusion results were similar to the patterns seen in hepatic encephalopathy. In cirrhotic patients, infusion of Fischer solution which contains small quantities of methionine and phenylalanine produced an increase in the concentrations of these 2 amino acids, probably because of impaired utilization by the injured liver. No marked alterations in serum aminograms, however, were observed in cirrhotic patients either immediately after, or 3 h after, the end of the Hep-OU infusion. Reduction of methionine, tyrosine and phenylalanine levels and elevation of the molar ratio of (valine+leucine+isoleucine) / (phenylalanine+tyrosine) were significant. The infusion of Hep-OU to patients with liver cirrhosis or subacute hepatitis resulted in clinical and neurological improvements and the restoration of the molar ratio of branched chain amino acids/aromatic amino acids.</p