6,451 research outputs found
Multi-Triplet Magnons in SrCu(BO) 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 SrCuZn(BO) 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(BO) 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 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
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 [3â6], thus indicating that this final part of the nephron plays an important role in the regulation of salt and water balance
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
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 â0-IIcâ (70-80%), while totally flat, classified as type â0-IIbâ 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 â0-IIbâ 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 â0-IIbâ gastric cancer. Ten had exclusively type â0-IIbâ, while two had combined types â0-IIb+IIcâ and â0-IIa+IIbâ 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 â0-IIbâ gastric cancer, resulting in long-term disease-free survival. NBI magnification endoscopy is effective for accurate optical identification and border marking of type â0-IIbâ early gastric cancer
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