Observation of two resonant structures in e+ e- -->pi+ pi- psi(2S) via initial-state radiation at Belle

The cross section for e+ e- --> pi+ pi- psi(2S) between threshold and sqrt[s]=5.5 GeV is measured using 673 fb(-1) of data on and off the Upsilon(4S) resonance collected with the Belle detector at KEKB. Two resonant structures are observed in the pi+ pi- psi(2S) invariant-mass distribution, one at 4361 +/- 9 +/- 9 MeV/c2 with a width of 74 +/- 15 +/- 10 MeV/c2, and another at 4664 +/- 11 +/- 5 MeV/c2 with a width of 48 +/- 15 +/- 3 MeV/c2, if the mass spectrum is parametrized with the coherent sum of two Breit-Wigner functions. These values do not match those of any of the known charmonium states.     

Fermi-surface reconstruction without breakdown of Kondo screening at the quantum critical point

Motivated by recent Hall-effect experiment in YbRh(2)Si(2), we study ground state properties of a Kondo lattice model in a two-dimensional square lattice using variational Monte Carlo method. We show that there are two types of phase transition, an antiferromagnetic transition and a topological one (Fermi-surface reconstruction). In a wide region of parameters, these two transitions occur simultaneously without the breakdown of Kondo screening, accompanied by a discontinuous change of the Hall coefficient. This result is consistent with the experiment and gives a novel theoretical picture for the quantum critical point in heavy-fermion systems.     

Study of decay mechanisms in B--->Lambdac+ppi- decays and observation of low-mass structure in the Lambdac+p system

Using a sample of 152 x 10(6) BB pairs accumulated with the Belle detector at the KEKB e+e- collider, we study the decay mechanism of three-body charmed decay B- --> Lambdac+ ppi-. The intermediate two-body decay B--->Sigmac (2455)0 p is observed for the first time with a branching fraction of (3.7 +/- 0.7 +/- 0.4 +/- 1.0) x 10(-5) and a statistical significance of 8.4sigma. We also observe a low-mass enhancement in the (Lambdac+p) system, which can be parametrized as a Breit-Wigner function with a mass of (3.35(-0.02)(+0.01) +/-0.02) GeV/c2 and a width of (0.07(-0.03)(+0.04) +/-0.04) GeV/c2. We measure its branching fraction to be (3.9(-0.7)(+0.8) +/- 0.4 +/- 1.0) x 10(-5) with a statistical significance of 6.2sigma. The errors are statistical, systematic, and that of the Lambdac+-->pK- pi+ decay branching fraction.     

Current-voltage characteristics of charge-ordered organic crystals

The current-voltage characteristics of layered organic crystals theta-(BEDT-TTF)2MZn(SCN)4 (M = Cs, Rb) follow the power law with a large exponent (e.g., 8.4 at 0.29 K for M = Cs) over a wide range of currents in the low-temperature insulating state. The power-law characteristics are attributed to electric field-induced unbinding of electron-hole pairs that are thermally excited in the background of the two-dimensional charge order. The magnitude of crossover electric fields from Ohmic to the power-law characteristics indicates that the electron-electron Coulomb interaction is significantly long-ranged: The screening length is greater than 10 molecule sites.     

The Weight-Bearing Rate on the Paretic Limb of Cerebrovascular Hemiplegic Patients Necessary for an Independent Obstacle Negotiation Gait

Purpose: The obstacle negotiation gait (ONG) is a fundamental activity of daily living. In cerebrovascular hemiplegic patients (stroke patients), the weight-bearing rate (WBR) on the paretic limb necessary for an independent ONG was studied. Methods: One hundred and seventeen stroke patients were involved. The patients'' average age at the time of the study was 67 years, and the average time from stroke onset was 102 days. There were 68 men and 49 women. Seventy patients were right hemiplegics, and 47 were left hemiplegics. The correlations between ONG and age, sex, body mass index (BMI), time from stroke onset, muscle strength of both the paretic and non-paretic limbs, Brunnstrom stage of the lower limbs, deep sensation, and the WBR on both the paretic and non-paretic limbs were studied. Patients who could perform ONG independently and safely were categorized as the independent group (IG), and those who needed observation or any assistance were categorized as the dependent group (DG). Results: The BMI, muscle strength of both the paretic and non-paretic limbs, Brunnstrom stage of the lower limbs, deep sensation and the WBR for both the paretic and non-paretic limbs were significantly different between the IG and DG groups. In particular, the WBR on the paretic limb was found to correlate significantly with the ONG, and a WBR value of 80.5% on the paretic limb gave a clear cut-off value. Conclusion: Although multiple factors influenced the ONG of stroke patients, the WBR on the paretic limb was the most influential.     

Three-dimensional vector holograms in photoreactive polymer dissolved liquid crystal composite

A detailed analysis of three-dimensional vector holograms is presented which were recorded in a photoreactive polymer dissolved liquid crystal. The diffraction properties of resultant periodic anisotropic structures were investigated. Experimental observations confirmed that the diffraction efficiencies of the structures varied with slight changes of the grating pitch, and also that they strongly depended on the incident angle of the probe beam. These diffraction properties were explained by the finite-difference time-domain optical simulations.     

Genetic algorithm-based design method for multilevel anisotropic diffraction gratings

We developed a method for the design of multilevel anisotropic diffraction gratings based on a genetic algorithm. The method is used to design the multilevel anisotropic diffraction gratings based on input data that represent the output from the required grating. The validity of the proposed method was evaluated by designing a multilevel anisotropic diffraction grating using the outputs from an orthogonal circular polarization grating. The design results corresponded to the orthogonal circular polarization grating structures that were used to provide outputs to act as the input data for the process. Comparison with existing design methods shows that the proposed method can reduce the number of human processes that are required to design multilevel anisotropic diffraction gratings. Additionally, the method will be able to design complex structures without any requirement for subsequent examination by a human designer. The method can contribute to the development of optical elements by designing multilevel anisotropic diffraction gratings.     

Detection and grading for esophageal varices in patients with chronic liver damage: comparison of gadolinium-enhanced and unenhanced steady-state coherent MR images

The purpose of this study was to compare observer interpreted steady-state coherent coronal images and gadolinium-enhanced axial images in terms of the detection and grading of esophageal varices. Magnetic resonance imaging (MRI) and gastrointestinal endoscopy were performed within 2 weeks in 90 patients with chronic liver damage, including 55 with untreated esophageal varices, for periodic screening purposes. Two blinded readers retrospectively reviewed T1- and T2-weighted images with gadolinium-enhanced (gadolinium image set) and steady-state coherent (coherent image set) images. Sensitivity for the detection of esophageal varices was higher (P<.001) in the gadolinium image set (76%) than in the coherent image set (35%); on the other hand, specificity was higher (P<.001) in the coherent image set (91%) than in the gadolinium image set (66%). Furthermore, area under the ROC curve was higher for the gadolinium image set (Az=0.823) than the coherent image set (Az=0.761) (P=.48). Moderate and weak positive correlations with endoscopic grades were found for the gadolinium image (r=0.48, P<.01) and coherent image sets (r=0.34, P=.018). The addition of steady-state coherent imaging to the current routine liver imaging protocol did not improve the detection or grading of esophageal varices, whereas gadolinium-enhanced imaging was found to be potentially valuable. Nevertheless, endoscopy was confirmed to be mandatory in patients with esophageal varices suspected by MRI of the liver.     

Magnetic resonance differentiation between T2 and T1 gallbladder carcinoma: significance of subserosal enhancement on the delayed phase dynamic study

Purpose

The aim of this study is to investigate whether subserosal enhancement on the delayed-phase dynamic magnetic resonance (MR) study (SED) can differentiate T2 from T1 gallbladder carcinoma (GBC).

Methods

The institutional research board approved this retrospective study. Between 1997 and 2006, there were surgically proven 11 T1 and 21 T2 GBC in 30 patients, all of whom had undergone preoperative contrast enhanced dynamic MR study, either with a 2D sequence (n=17) or 3D sequences (n=15). All images were reviewed by two radiologists for the presence of SED, and receiver operating characteristic (ROC) curve analysis was performed. Sensitivity, specificity, positive and negative predictive values were calculated by consensus.

Results

The areas under the ROC curves of the two readers were 0.91 and 0.86, and the kappa value was 0.78. Of the 21 T2 GBC, 18 and 3 showed positive and negative SED, respectively. Of the 11 T1 GBC, 1 and 10 showed positive and negative SED, respectively. The sensitivity, specificity, positive and negative predictive values of SED for diagnosing T2 lesions were 86%, 88%, 91% and 77%, respectively.

Conclusions

In conclusion, SED may be a useful sign to differentiate T2 from T1 GBC, which would affect the preoperative surgical planning of the patients.