Charge ordering in theta-(BEDT-TTF)_2 X materials

We investigate theoretically charge ordered states on the anisotropic triangular lattice characteristic of the theta-(BEDT-TTF)_2 X materials. Using exact diagonalization studies, we establish that the charge order (CO) pattern corresponds to a ``horizontal'' stripe structure, with ...1100... CO along the two directions with larger electron hopping (p-directions), and ...1010... CO along the third direction (c-direction). The CO is accompanied by co-operative bond dimerizations along all three directions in the highest spin state. In the lowest spin state bonds along the p-directions are tetramerized. Our theory explains the occurence of a charge-induced high temperature transition as well as a spin gap transition at lower temperature.Comment: 4 pages, 4 eps figures, uses jpsj2.cl

Prediction of the remnant liver hypertrophy ratio after preoperative portal vein embolization.

Background: Portal vein embolization (PVE) is considered to improve the safety of major hepatectomy. Various conditions might affect remnant liver hypertrophy after PVE. The aim of the present study was to clarify the factors that affect remnant liver hypertrophy and to establish a prediction formula for the hypertrophy ratio. Methods: Fifty-nine patients who underwent preoperative PVE for cholangiocarcinoma (39 patients), metastatic carcinoma (10 patients), hepatocellular carcinoma (8 patients), and other diseases (2 patients) were enrolled in this study. For the prediction of the hypertrophy ratio, a formula with stepwise multiple regression analysis was set up. The following parameters were used: age, gender, future liver remnant ratio to total liver (FLR%), plasma disappearance rate of indocyanine green (ICGK), platelet count, prothrombin activity, serum albumin, serum total bilirubin at the time of PVE and the maximum value before PVE (Max Bil), as well as a history of cholangitis, diabetes mellitus, and chemotherapy. Results: The mean hypertrophy ratio was 28.8%. The 5 parameters detected as predictive factors were age (p = 0.015), FLR% (p < 0.001), ICGK (p = 0.112), Max Bil (p < 0.001), and history of chemotherapy (p = 0.007). The following prediction formula was established: 101.6 - 0.78 × age - 0.88 × FLR% + 128 × ICGK - 1.48 × Max Bil (mg/dl) - 21.2 × chemotherapy. The value obtained using this formula significantly correlated with the actual value (r = 0.72, p < 0.001). A 10-fold cross validation also showed significant correlation (r = 0.62, p < 0.001), and a hypertrophy ratio <20% was predictable with a sensitivity of 100% and a specificity of 90.9%. Moreover, technetium-99m-diethylenetriaminepentaacetic acid-galactosyl human serum albumin scintigraphy showed a significantly smaller increase in the uptake ratio of the remnant liver in patients with prediction values <20% than in those with values ≥20% (6.8 vs. 20.8%, p = 0.030). Conclusions: The prediction formula can prognosticate the hypertrophy ratio after PVE, which may provide a new therapeutic strategy for major hepatectomy

Friedel oscillations in a two-band Hubbard model for CuO chains

Friedel oscillations induced by open boundary conditions in a two-band Hubbard model for CuO chains are numerically studied. We find that for physically realistic parameters and close to quarter filling, these oscillations have a 2k_F modulation according with experimental results on YBa_2Cu_3O_{7-delta}. In addition, we predict that, for the same parameters, as hole doping is reduced from quarter filling to half filling, Friedel oscillations would acquire a 4k_F modulation, typical of a strongly correlated electrons regime. The 4k_F modulation dominates also in the electron doped region. The range of parameters varied is very broad, and hence the results reported could apply to other cuprates and other strongly correlated compounds with quasi-one dimensional structures. On a more theoretical side, we stress the fact that the copper and oxygen subsystems should be described by two different Luttinger liquid exponents.Comment: 7 pages, 7 eps figure

Theoretical Aspects of Charge Ordering in Molecular Conductors

Theoretical studies on charge ordering phenomena in quarter-filled molecular (organic) conductors are reviewed. Extended Hubbard models including not only the on-site but also the inter-site Coulomb repulsion are constructed in a straightforward way from the crystal structures, which serve for individual study on each material as well as for their systematic understandings. In general the inter-site Coulomb interaction stabilizes Wigner crystal-type charge ordered states, where the charge localizes in an arranged manner avoiding each other, and can drive the system insulating. The variety in the lattice structures, represented by anisotropic networks in not only the electron hopping but also in the inter-site Coulomb repulsion, brings about diverse problems in low-dimensional strongly correlated systems. Competitions and/or co-existences between the charge ordered state and other states are discussed, such as metal, superconductor, and the dimer-type Mott insulating state which is another typical insulating state in molecular conductors. Interplay with magnetism, e.g., antiferromagnetic state and spin gapped state for example due to the spin-Peierls transition, is considered as well. Distinct situations are pointed out: influences of the coupling to the lattice degree of freedom and effects of geometrical frustration which exists in many molecular crystals. Some related topics, such as charge order in transition metal oxides and its role in new molecular conductors, are briefly remarked.Comment: 21 pages, 19 figures, to be published in J. Phys. Soc. Jpn. special issue on "Organic Conductors"; figs. 4 and 11 replaced with smaller sized fil

The N-linked oligosaccharide at FcγRIIIa Asn-45: an inhibitory element for high FcγRIIIa binding affinity to IgG glycoforms lacking core fucosylation

Human leukocyte receptor IIIa (FcγRIIIa) plays an important role in mediating therapeutic antibodies’ antibody-dependent cellular cytotoxicity (ADCC), which is closely related to the clinical efficacy of anticancer processes in humans in vivo. The removal of the core fucose from oligosaccharides attached to the Fc region of antibodies improves FcγRIIIa binding, allowing the antibodies to enhance dramatically the antibody effector functions of ADCC. In this study, the contribution of FcγRIIIa oligosaccharides to the strength of the FcγRIIIa/antibody complex was analyzed using a serial set of soluble human recombinant FcγRIIIa lacking the oligosaccharides. A nonfucosylated antibody IgG1 appeared to have a significantly higher affinity to the wild-type FcγRIIIa fully glycosylated at its five N-linked oligosaccharide sites than did the fucosylated IgG1, and this increased binding was almost abolished once all of the FcγRIIIa glycosylation was removed. Our gain-of-function analysis in the FcγRIIIa oligosaccharide at Asn-162 (N-162) confirmed that N-162 is the element required for the high binding affinity to nonfucosylated antibodies, as previously revealed by loss-of-function analyses. Interestingly, beyond our expectation, the FcγRIIIa modified by N-162 alone showed a significantly higher binding affinity to nonfucosylated IgG1 than did the wild-type FcγRIIIa. Attachment of the other four oligosaccharides, especially the FcγRIIIa oligosaccharide at Asn-45 (N-45), hindered the high binding affinity of FcγRIIIa to nonfucosylated IgG1. Our data clearly demonstrated that N-45 is an inhibitory element for the high FcγRIIIa binding affinity mediated by N-162 to nonfucosylated antibodies. This information can be exploited for the structural-based functional study of FcγRIIIa

Observation by an Air-Shower Array in Tibet of the Multi-TeV Cosmic-Ray Anisotropy due to Terrestrial Orbital Motion Around the Sun

We report on the solar diurnal variation of the galactic cosmic-ray intensity observed by the Tibet III air shower array during the period from 1999 to 2003. In the higher-energy event samples (12 TeV and 6.2 TeV), the variations are fairly consistent with the Compton-Getting anisotropy due to the terrestrial orbital motion around the sun, while the variation in the lower-energy event sample (4.0 TeV) is inconsistent with this anisotropy. This suggests an additional anisotropy superposed at the multi-TeV energies, e.g. the solar modulation effect. This is the highest-precision measurement of the Compton-Getting anisotropy ever made.Comment: 4 pages, 2 figures, includes .bbl fil

Improved Measurement of the Partial-Rate CP Asymmetry in B+ -> K0pi+ and B- -> K0bar pi- Decays

We report an improved measurement of the partial-rate CP asymmetry in B+ => K0pi+ and B- => K0bar pi- decays. The analysis is based on a data sample of 85 million BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e+ e- storage ring. We measure Acp(K0pi+-) = 0.07^{+0.09 +0.01}_{-0.08 -0.03}, where the first and second errors are statistical and systematic, respectively; the corresponding 90% confidence-level interval is -0.10 < Acp(K0pi+-) < 0.22 .Comment: 7 pages, 8 figures, submitted to Phys. Rev.

Dynamics of the Density Matrix in Contact with a Thermal Bath and the Quantum Master Equation

We study the structure of the time evolution of the density matrix in contact with a thermal bath in a standard projection operator sheme. The reduced density matrix of the system in the steady state is obtained by tracing out the degree of freedom of the thermal bath from the equilibrium density matrix of the total system. This reduced density matrix is modified by the interaction, and is different from that of the equilibrium of the system alone. We explicitly calculate the contribution of each term in quantum master equation to the realization of the steady state density matrix, and make clear roles of each term. By making use of the role of each term, the properties of the commonly used quantum master equation are examined.Comment: 17 pages, to appear in JPS