Studies on X-ray Thomson Scattering from Antiferroquadrupolar Order in TmTe

We study Thomson scattering from the antiferroquadrupole ordering phase in TmTe. On the basis of the group theoretical treatment, we classify the selection rules of the scattering intensity governed by the orientation of the scattering vector G. Then, numerical verification is performed by invoking the ground states which are deduced from a J=7/2 multiplet model. The obtained intensity varies drastically depending on the magnitude and direction of G. We also calculate the scattering intensities under the applied field for H//(001) and (110). Their results behave differently when the orientation of G is changed, which is ascribed to the difference of their primary order parameters; O_{2}^{0} and O_{2}^{2} for H // (001) and (110), respectively. We make critical comparisons between our results for TmTe and the experimental ones for CeB_6. First, we assert that the intensities expected from TmTe at several forbidden Bragg spots are sufficient enough to be experimentally detected. Second, their intensities at (7/2,1/2,1/2) differ significantly and may be attributed to the difference of the order parametersbetween the \Gamma_3-type (O_{2}^{2} and O_{2}^{0}) and \Gamma_5-type (O_{yz}, O_{zx}, and O_{xy}) components, respectively.Comment: 18 pages, 3 figures, to be published in J. Phys. Soc. Jp

The inferior caval vein draining into the left atrial cavity : a rare case

The inferior vena cava (IVC) draining into the left atrium (LA) is exceedingly rare in the setting of the usual atrial arrangement (situs solitus). This article describes a patient with this unique anomaly, and its repair.peer-reviewe

Exciton Mediated Triplet Superconductivity in Th System PrOs4Sb12

In PrOs4Sb12, the lowest-lying singlet and triplet states in a Pr 4f^2 configuration hybridize with conduction electrons having local a_u and t_u point-group symmetries. It is shown that for an attractive triplet pairing interaction, the orbital degrees of freedom of the t_u component are important. In addition, the Th point-group symmetry characteristic of skutterudites plays an important role in stabilizing triplet superconductivity.Comment: 4 pages, 2 figure

Antiferroquadrupolar Order in the Magnetic Semiconductor TmTe

The physical properties of the antiferroquadrupolar state occurring in TmTe below TQ=1.8 K have been studied using neutron diffraction in applied magnetic fields. A field-induced antiferromagnetic component k = (1/2,1/2,1/2) is observed and, from its magnitude and direction for different orientations of H, an O(2,2) quadrupole order parameter is inferred. Measurements below TN ~= 0.5 K reveal that the magnetic structure is canted, in agreement with theoretical predictions for in-plane antiferromagnetism. Complex domain repopulation effects occur when the field is increased in the ordered phases, with discontinuities in the superstructure peak intensities above 4 T.Comment: 6 pages, 6 figures, Presented at the International Conference on Strongly Correlated Electrons with Orbital Degrees of Freedom (ORBITAL 2001), September 11-14, 2001 (Sendai, JAPAN). To appear in: Journal of the Physical Society of Japan (2002

Superoxide dismutase analog (Tempol: 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine 1-oxyl) treatment restores erectile function in diabetes-induced impotence.

We hypothesized that the administration of the superoxide dismutase (SOD) mimetic Tempol (4-hydroxy-2, 2, 6, 6-tetramethylpiperidine 1-oxyl) may reverse diabetes-induced erectile dysfunction. To test this hypothesis, reactive oxygen species-related genes (SOD1, SOD2, GP x 1, CAT, NOS2, NOS3) were tested, erectile functional studies and immunohistochemical analysis were carried out in diabetic rats treated with or without Tempol. Thirty Sprague-Dawley (3-4 months old) rats were divided into three groups (n=10 each), 20 with diabetes (diabetic control and Tempol treatment) and 10 healthy controls. At 12 weeks after the induction of diabetes by streptozotocin and Tempol treatment, all groups underwent in vivo cavernous nerve stimulation. Rat crura were harvested and the expression of antioxidative defense enzymes were examined by semi-quantitative reverse transcriptase PCR (RT-PCR). To confirm the RT-PCR results, we carried out immunohistochemistry (IHC) for catalase (CAT) and iNOS (NOS2). Nitration of tyrosine groups in proteins was also examined by IHC. Mean intracavernous pressure in the diabetic group was significantly lower than in the healthy controls (P <0.001) and was reversed by Tempol treatment (P <0.0108). NOS2 protein expression was significantly increased in diabetic animals compared with healthy controls and Tempol restored NOS2 protein level. Nitrotyrosine was also higher in diabetic animals and although Tempol treatment decreased its formation, it remained higher than that found in healthy controls. This study suggests that Tempol treatment increased erectile function through modulating oxidative stress-related genes in diabetic rats. This is the first report about the relationship between diabetes-induced erectile dysfunction and oxidative stress, and antioxidative therapy using the superoxide dismutase mimetic, Tempol, to restore erectile function

Synapse development is regulated by microglial THIK-1 K+ channels

Microglia are the resident immune cells of the central nervous system. They constantly survey the brain parenchyma for redundant synapses, debris, or dying cells, which they remove through phagocytosis. Microglial ramification, motility, and cytokine release are regulated by tonically active THIK-1 K+ channels on the microglial plasma membrane. Here, we examined whether these channels also play a role in phagocytosis. Using pharmacological blockers and THIK-1 knockout (KO) mice, we found that a lack of THIK-1 activity approximately halved both microglial phagocytosis and marker levels for the lysosomes that degrade phagocytically removed material. These changes may reflect a decrease of intracellular [Ca2+]i activity, which was observed when THIK-1 activity was reduced, since buffering [Ca2+]i reduced phagocytosis. Less phagocytosis is expected to result in impaired pruning of synapses. In the hippocampus, mice lacking THIK-1 expression had an increased number of anatomically and electrophysiologically defined glutamatergic synapses during development. This resulted from an increased number of presynaptic terminals, caused by impaired removal by THIK-1 KO microglia. The dependence of synapse number on THIK-1 K+ channels, which control microglial surveillance and phagocytic ability, implies that changes in the THIK-1 expression level in disease states may contribute to altering neural circuit function

Determination of the Antiferroquadrupolar Order Parameters in UPd3

By combining accurate heat capacity and X-ray resonant scattering results we have resolved the long standing question regarding the nature of the quadrupolar ordered phases in UPd_3. The order parameter of the highest temperature quadrupolar phase has been uniquely determined to be antiphase Q_{zx} in contrast to the previous conjecture of Q_{x^2-y^2} . The azimuthal dependence of the X-ray scattering intensity from the quadrupolar superlattice reflections indicates that the lower temperature phases are described by a superposition of order parameters. The heat capacity features associated with each of the phase transitions characterize their order, which imposes restrictions on the matrix elements of the quadrupolar operators.Comment: 4 pages, 5 figure

Exciton Mediated Superconductivity in PrOs4Sb12

The most important character of the exotic superconductor PrOs4Sb12 is the existence of low-lying excitations (excitons) with a finite energy gap and it appears as the magnetic field-induced order above 4.5 T. We focus on the a_u conduction band, which hybridizes with a Pr 4f^2 state strongly, coupled to the excitons. It results in an attractive interaction between the conduction electrons. The symmetry of the superconducting order parameter is determined by dispersion relation of the exciton. For the bcc system PrOs4Sb12, a d-wave state [kx ky + omega ky kz + omega^2 kz kx, omega=exp(pm i 2 pi/3)] is stabilized with broken time reversal symmetry.Comment: 4 page

Self-Consistent Perturbation Theory for Thermodynamics of Magnetic Impurity Systems

Integral equations for thermodynamic quantities are derived in the framework of the non-crossing approximation (NCA). Entropy and specific heat of 4f contribution are calculated without numerical differentiations of thermodynamic potential. The formulation is applied to systems such as PrFe4P12 with singlet-triplet crystalline electric field (CEF) levels.Comment: 3 pages, 2 figures, proc. ASR-WYP-2005 (JAERI

Detection of Neutron Scattering from Phase IV of Ce0.7La0.3B6: A Confirmation of the Octupole Order

We have performed a single crystal neutron scattering experiment on Ce0.7La0.3B6 to investigate the order parameter of phase IV microscopically. Below the phase transition temperature 1.5 K of phase IV, weak but distinct superlattice reflections at the scattering vector (h/2,h/2,l/2) (h, l = odd number) have been observed by neutron scattering for the first time. The intensity of the superlattice reflections is stronger for high scattering vectors, which is quite different from the usual magnetic form factor of magnetic dipoles. This result directly evidences that the order parameter of phase IV has a complex magnetization density, consistent with the recent experimental and theoretical prediction in which the order parameter is the magnetic octupoles Tbeta with Gamma5 symmetry of point group Oh. Neutron scattering experiments using short wavelength neutrons, as done in this study, could become a general method to study the high-rank multipoles in f electron systems.Comment: 4 pages, 4 figure