Multi-Triplet Magnons in SrCu2_2(BO3_3)2_2 Studied by Thermal Conductivity Measurements in Magnetic Fields

We have measured the thermal conductivity parallel to the a-axis of the Zn-free and 1% Zn-substituted SrCu$_{2-x}$Zn$_x$(BO$_3$)$_2$ in magnetic fields up to 14 T, in order to examine the thermal conductivity due to the multi-triplet magnons. It has been found that the thermal conductivity peak observed in the spin gap state is suppressed by the substitution of Zn for Cu in high magnetic fields above 6 T, while it is not changed in low magnetic fields below 6 T. The results suggest that the thermal conductivity peak in the spin-gap state of SrCu$_2$(BO$_3$)$_2$ is composed of not only thermal conductivity due to phonons but also that due to the multi-triplet magnons in high fields above 6 T.Comment: 7 pages, 2 figure

Energy diffusion in frustrated quantum spin chains exhibiting Gaussian orthogonal ensemble level statistics

Frustrated quantum $XXZ$ spin chains with the next-nearest-neighbor (NNN) couplings are typically deterministic many-body systems exhibiting Gaussian orthogonal ensemble (GOE) spectral statistics. We investigate energy diffusion for these spin chains in the presence of a periodically oscillating magnetic field. Diffusion coefficients are found to obey the power law with respect to both the field strength and driving frequency with its power varying depending on the linear response and non-perturbative regimes. The widths of the linear response and the non-perturbative regimes depend on the strength of frustrations. We have also elucidated a mechanism for oscillation of energy diffusion in the case of weakened frustrations.Comment: 6 pages, 6 figure

Unexpected non-Wigner behavior in level-spacing distributions of next-nearest-neighbor coupled XXZ spin chains

The level-spacing distributions of XXZ spin chains with next-nearest-neighbor couplings are studied under periodic boundary conditions. We confirm that integrable XXZ spin chains mostly have the Poisson distribution as expected. On the contrary, the level-spacing distributions of next-nearest-neighbor coupled XXZ chains are given by non-Wigner distributions. It is against the expectations, since the models are nonintegrable.Comment: 4 pages, 4 figures, to be published in Physical Review

Characterization of tumour cell aggregation promoting factor from rat ascites hepatoma cells: Separation of two factors with different antigenic property.

The previously described glycoprotein that promotes tumour cell aggregation, derived from rat ascites hepatoma cells and capable of partial purification by chromatography, was found to be a mixture of 2 factors with different antigenic property. One was not absorbed by immunoadsorbent chromatography with anti-rat serum antibody and the other was. The action of the unabsorbed factor was clearly more potent than that of the absorbed factor. Both the factors were found in the serum of tumour bearing rats and the action of the unabsorbed factor was also more potent than that of the absorbed factor; its amount increased with time after i.p. inoculation of the cells. The serum of healthy rats contained the absorbed factor but not the unabsorbed factor. It was thus assumed that the unabsorbed factor was associated with the hepatoma cell surface itself and released into the serum, while the absorbed factor was associated with serum protein coating the cell

Water, urea, sodium, chloride, and potassium transport in the in vitro isolated perfused papillary collecting duct

The collecting ducts are formed in the renal cortex by the connection of several nephrons. They descend within the medullary rays of the cortex, penetrate the outer medulla, and in the inner medulla successively fuse together. Based on these topographical considerations, we can recognize three segments of the collecting duct system: the cortical collecting tubule, the outer medullary collecting duct, and the papillary collecting duct. In this review, we call papillary collecting duct (PCD) that part of the collecting duct system that extends from the junction of outer medulla and inner medulla to the area cribosa. The collecting ducts in the outer medullary zone rarely have branches; however, such branches present in the inner zone have hampered study by micropuncture and microcatheterization techniques. The cortical collecting tubule (CCT) contains two types of cells, principal and intercalated cells, whereas in most animals the PCD contains only principal cells [1]. The general ultrastructure of the PCD cell seems simpler than that of the cortical collecting tubule, suggesting that the PCD is less specialized and less metabolically active than other nephron segments [2]. However, the accumulated data reveal a remarkable reabsorptive capacity for water and sodium by the PCD [3–6], thus indicating that this final part of the nephron plays an important role in the regulation of salt and water balance

Magnetic-field effects on the charge-spin stripe order in La-214 high-Tc cuprates

Magnetic-field effects on the charge-spin stripe order in La-214 high-Tc cuprates have been investigated from measurements of the in-plane electrical-resistivity, Rho_ab_. In La_2-x_Ba_x_CuO_4_ with x=0.10 and La_2-x_Sr_x_CuO_4_ with x=0.115 where the incommensurate charge peaks are weak and unobservable in zero field in elastic neutron-scattering measurements, respectively, the normal-state value of Rho_ab_ at low temperatures markedly increases with increasing field up to 27 T. For La_2-x_Ba_x_CuO_4_ with x=0.11 and Zn-substituted La_2-x_Sr_x_Cu_1-y_Zn_y_O_4_ with x=0.115 and y=0.02 where the charge stripe order is fairly stabilized in zero field, on the other hand, the increase in Rho_ab_ with increasing field is negligibly small. In conclusion, when the charge-spin stripe order is not fully stable in zero field, magnetic field operates to stabilize the charge-spin stripe order. The value of Rho_ab_ increases with increasing field depending on the stability of the charge stripe order.Comment: 4 pages, 2 figures, Proceedings of Yamada Conference LX on Research in High Magnetic Fields (RHMF2006) (Satellite of ICM2006

Effective optical identification of type "0-IIb" early gastric cancer with narrow band imaging magnification endoscopy, successfully treated by endoscopic submucosal dissection

Background Endoscopic submucosal dissection (ESD) is currently considered the minimal invasive endoscopic treatment for early gastric cancer. Most superficial gastric neoplastic lesions are depressed type ”0-IIc” (70-80%), while totally flat, classified as type ”0-IIb” early gastric cancer, is rarely reported (0.4%). The aim of the present study was to assess the efficacy of narrow band imaging (NBI) magnification endoscopy in identifying type “0-IIb” early gastric cancer and ESD treatment with curative intention.Methods Twelve of 615 (2%) patients (10 males, median 72 years), treated by ESD at our center, were diagnosed as type “0-IIb” gastric cancer. Ten had exclusively type “0-IIb”, while two had combined types “0-IIb+IIc” and “0-IIa+IIb” gastric cancer. Initial diagnosis was made during screening gastroscopy, while NBI magnification endoscopy combined with indigo-carmine chromoendoscopy were also used.Results White light endoscopy showed only superficial redness. One patient with signet-ring carcinoma showed whitish appearance. Indigo-carmine chromoendoscopy showed better visualization, while NBI magnification endoscopy revealed abnormal mucosal microsurface and microvascular findings which enabled border marking. ESD with curative intention was completed without complications. Histological examination showed complete (R0) resection, in 10 patients (83%). One patient with positive margins received additional surgery (8%). Mean procedure time was 149 (range 60-190) min. One to six years post-ESD all patients remain alive.Conclusions ESD is considered a safe and effective curative treatment for type “0-IIb” gastric cancer, resulting in long-term disease-free survival. NBI magnification endoscopy is effective for accurate optical identification and border marking of type “0-IIb” early gastric cancer

Orbital Degeneracy and Peierls Instability in Triangular Lattice Superconductor Ir1−x_{1-x}Ptx_xTe2_2

We have studied electronic structure of triangular lattice Ir$_{1-x}$Pt$_x$Te$_2$ superconductor using photoemission spectroscopy and model calculations. Ir $4f$ core-level photoemission spectra show that Ir $5d$ $t_{2g}$ charge modulation established in the low temperature phase of IrTe$_2$ is suppressed by Pt doping. This observation indicates that the suppression of charge modulation is related to the emergence of superconductivity. Valence-band photoemission spectra of IrTe$_2$ suggest that the Ir $5d$ charge modulation is accompanied by Ir $5d$ orbital reconstruction. Based on the photoemission results and model calculations, we argue that the orbitally-induced Peierls effect governs the charge and orbital instability in the Ir$_{1-x}$Pt$_x$Te$_2$.Comment: 5 pages,4 figure