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Y Asano

Publications and source records attributed to Y Asano.

At least 55 records · Page 3Linked to original sources
PubMed2005

Observation of a near-threshold omegaJ/psi mass enhancement in exclusive B-->KomegaJ/psi decays.

We report the observation of a near-threshold enhancement in the omegaJ/psi invariant mass distribution for exclusive B-->KomegaJ/psi decays. The results are obtained from a 253 fb(-1) data sample that contains 275 x 10(6) BB pairs that were collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e(+)e(-) collider. The statistical significance of the omegaJ/psi mass enhancement is estimated to be greater than 8sigma.

Journal Article↗
PubMed2005

Study of B0-->rho+/- pi-/+ time-dependent CP violation at Belle.

We present a time-dependent analysis of CP violation in B0-->rho(+/-)pi(-/+) decays based on a 140 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at KEKB. We obtain the charge asymmetry A(rhopi)(CP)=-0.16+/-0.10(stat)+/-0.02(syst). An unbinned maximum-likelihood fit to the Deltat distributions yields C(rhopi)=0.25+/-0.17(stat)+0.02-0.06(syst), DeltaC(rhopi)=0.38+/-0.18(stat)+0.02-0.04(syst), S(rhopi)=-0.28+/-0.23(stat)+0.10-0.08(syst), and DeltaS(rhopi)=-0.30+/-0.24(stat)+/-0.09(syst). The direct CP violation parameters for B-->rho(+)pi(-) and B-->rho(-)pi(+) decays are A(+-)(rhopi)=-0.02+/-0.16(stat)+0.05-0.02(syst) and A(-+)(rhopi)=-0.53+/-0.29(stat)+0.09-0.04(syst).

Journal Article↗
PubMed2005

Observation of an isotriplet of excited charmed baryons decaying to lambda+c pi.

We report the observation of an isotriplet of excited charmed baryons, decaying into Lambda(+)(c)pi(-), Lambda(+)(c)pi(0), and Lambda(+)(c)pi(+). We measure the mass differences M(Lambda(+)(c)pi)-M(Lambda(+)(c)) and widths to be 515.4(+3.2+2.1)(-3.1-6.0) MeV/c(2), 61(+18+22)(-13-13) MeV for the neutral state; 505.4(+5.8+12.4)(-4.6-2.0) MeV/c(2), 62(+37+52)(-23-38) MeV for the charged state; and 514.5(+3.4+2.8)(-3.1-4.9) MeV/c(2), 75(+18+12)(-13-11) MeV for the doubly charged state, where the uncertainties are statistical and systematic, respectively. These results are obtained from a 281 fb(-1) data sample collected with the Belle detector near the Upsilon(4S) resonance, at the KEKB asymmetric energy e(+)e(-) collider.

Journal Article↗
PubMed2005

Observation of B+-->K1(1270)+gamma.

We report the observation of the radiative decay B+-->K1(1270)(+) gamma using a data sample of 140 fb(-1) taken at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- collider. We find the branching fraction to be B(B+-->K1(1270)(+)gamma)=(4.3+/-0.9(stat.)+/-0.9(syst.))x10(-5) with a significance of 7.3sigma. We find no significant signal for B+-->K1(1400)(+)gamma and set an upper limit B(B+-->K1(1400)(+)gamma)<1.5 x 10(-5) at the 90% confidence level. We also measure inclusive branching fractions for B+-->K+pi+pi-gamma and B0-->K0pi+pi-gamma in the mass range 1 GeV/c(2)<M(K+(0)pi+pi-)<2 GeV/c(2).

Journal Article↗
PubMed2005

Study of the suppressed decays B- -->[K+pi-](D)K- and B- -->[K+pi-]Dpi-.

We report a study of the suppressed decays B--->[K(+)pi(-)](D)K- and B--->[K(+)pi(-)](D)pi(-), where [K(+)pi(-)](D) indicates that the K+pi(-) pair originates from a neutral D meson. These decay modes are sensitive to the unitarity triangle angle varphi(3). We use a data sample containing 275 x 10(6) BB pairs recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) storage ring. The signal for B--->[K(+)pi(-)](D)K- is not statistically significant, and we set a limit r(B)<0.27 at 90% confidence level, where r(B) is the magnitude of the ratio of amplitudes |A(B--->D 0K-)/A(B--->D0K-)|. We observe a signal with 6.4sigma statistical significance in the related mode, B--->[K(+)pi(-)](D)pi(-).

Journal Article↗
PubMed2005

Search for D0-D0 mixing in D0 --> K+ pi(-) decays and measurement of the doubly-Cabibbo-suppressed decay rate.

We have searched for mixing in the D(0)-D (0) system by measuring the decay-time distribution of D(0) --> K(+) pi(-) decays. The analysis uses 90 fb(-1) of data collected by the Belle detector at the KEKB e(+) e(-) collider. We fit the decay-time distribution for the mixing parameters x' and y' and also for the parameter R(D), which is the ratio of the rate for the doubly-Cabibbo-suppressed decay D(0)--> K+ pi(-) to that for the Cabibbo-favored decay D(0)--> K-pi(+). We do these fits both assuming CP conservation and allowing for CP violation. We use a frequentist method to obtain a 95% C.L. region in the x'(2) - y' plane. Assuming no mixing, we measure R(D) = (0.381 +/- 0.017(+0.008)(-0.016))%.

Journal Article↗
PubMed2005

Observation of B0-->D*sJ(2317)+K- decay.

The decays B0-->D+sJK- and B0-->D-sJpi+ are studied for the first time. A significant signal is observed in the B0-->D*sJ(2317)+K- decay channel with B(B0-->D*sJ(2317)+K-) x B(D*sJ(2317)+-->D+spi0)=(5.3(+1.5)(-1.3)+/-0.7+/-1.4) x 10(-5). No signals are observed in the B0-->D*sJ(2317)-pi+, B0-->DsJ(2460)+K-, and B 0-->DsJ(2460)-pi+ decay modes, and upper limits are obtained. The analysis is based on a data set of 140 fb(-1) collected by the Belle experiment at the asymmetric e+e- collider KEKB.

Journal Article↗
PubMed2005

Measurement of the branching fraction and CP asymmetry in B+ --> rho+pi0.

We report a measurement of the branching fraction for the decay B+ --> rho(+) pi(0) based on a 140 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric e(+)e(-) collider. We measure the branching fraction B(B(+) --> rho(+)pi(0)) = (13.2 +/- 2.3(stat)(+1.4)(-1.9)(syst)) x 10(-6), and the CP-violating asymmetry A(CP)(B-/+ -->rho(-/+)pi(0))=0.06 +/- 0.17(stat)(+0.04)(-0.05)(syst).

Journal Article↗
PubMed2005

In vitro and in vivo analysis of human herpesvirus-6 U90 protein expression.

In order to establish a reliable method for the detection of human herpesvirus-6 (HHV-6) B antigens in peripheral blood mononuclear cells (PBMCs) collected from HHV-6 infected patients, we created a polyclonal antibody against the HHV-6 B U90 protein (IEA/ex3) and used it to examine the expression of this protein in virus-infected cells and patients' PBMCs. This antibody reacted with 170 and 195 kDa proteins in HHV-6 B-infected cord blood mononuclear cells. The IEA/ex3 antigen was detected in cord blood mononuclear cells at 6 hr post-infection, and the number of infected cells reached its maximum at 48 hr post-infection. The antigen stained in a punctate pattern and partially localized to the promyelocytic leukemia (PML) protein body. We also examined 60 PBMC samples from 60 febrile children (3-19 months old) and detected IEA/ex3 antigen in the PBMCs by laser-scanning microscopy. HHV-6 was isolated from 31 of the 60 samples. The sensitivity and specificity of the antigen detection were 84% (26/31) and 97% (28/29), respectively, in the samples with virus detected. The mean number of antigen-positive PBMCs was 409/10(6) cells in 20 samples with viral isolation. A significant correlation (r = 0.566; P = 0.008) was observed between the viral load and number of antigen-positive cells. Although IEA/ex3 antigen was detected by laser-scanning microscopy in PBMCs (without cultivation) collected from six patients with isolated virus, it was detected in only one sample by conventional fluorescence microscopy. Increasing the intensity by cultivation (24 hr) resulted in a higher detection rate (5/6) even by conventional fluorescence microscopy, which is available in most hospital laboratories.

Antibodies, Viral↗
PubMed2005

Sprouting from arteriovenous shunt vessels with increased blood flow.

The purpose of this study was to evaluate the effect of increased blood flow on angiogenesis at the large vessels. The arteriovenous (AV) shunt was made on the thigh of male Wistar rats (n = 27) to increase blood flow, wrapped with artificial skin dermis, which consisted of a silicon outer layer, and isolated from surrounding tissues. Blood flow increased from 2.40 +/- 0.77 to 35.8 +/- 8.7 ml min(-1) (14.9 times), and the shear stress index (relative value of shear stress) increased from 10.7 +/- 3.6 to 73.4 +/- 18.1 (6.85 times) 60 min after the shunt formation. Newly formed vessels were observed around the AV shunt loop. Scanning electron micrographs at the AV shunt vessel lumen showed modified endothelial cells at day 7 and a remarkable number of pores at day 14. The volume of newly formed vessels was increased 12 times from day 5 to day 14. The mechanical factor of shear stress was considered the major stimulator of angiogenesis. This is the first report of electron-microscopic observation of sprouts from a large vessel lumen. The new AV shunt model is useful for basic research on angiogenesis at the large vessels in vivo and, furthermore, could generate vascularised tissues with various cultured cells.

Animals↗
PubMed2005

Comparison of synchrotron radiation calculations between analytical codes (STAC8, photon) and Monte Carlo codes (FLUKA, EGS4).

STAC8 is a significant improvement upon its predecessor PHOTON and is a valuable analytical code for quick and conservative beamline shielding designs for synchrotron radiation (SR) facilities. In order to check the applicability, accuracy and limitations of STAC8, studies were conducted to compare the results of STAC8 with those of PHOTON with calculations using the FLUKA and EGS4 Monte Carlo codes. Doses and spectra for scattered SR in a few beam-target-shield geometries were calculated, with and without photon linear polarisation effects. Areas for expanding the STAC8 capabilities, for example, features of the mirror-reflected lights and double-Compton light calculations and the use of monochromatic light have been identified. Some of these features have been implemented and benchmarked against Monte Carlo calculations. Reasonable agreements were found between the STAC8 and Monte Carlo calculations.

Algorithms↗
PubMed2005

Sclerosing panniculitis is associated with pulmonary hypertension in systemic sclerosis.

BACKGROUND: There have been no reports of patients with sclerosing panniculitis and systemic sclerosis (SSc). OBJECTIVES: To evaluate the incidence of sclerosing panniculitis in patients with SSc, and to investigate the clinical features of such cases. METHODS: In total, 128 patients with SSc treated at our clinic were investigated retrospectively. RESULTS: SSc patients with sclerosing panniculitis had pulmonary hypertension (PH), especially isolated PH, at a significantly higher incidence than those without. Among the SSc patients with PH, those with sclerosing panniculitis had pulmonary infarctions at a higher incidence than those without. CONCLUSIONS: Our results suggest that thrombosis caused by venous hypertension of the leg may be the main cause of PH in patients with SSc and sclerosing panniculitis. Sclerosing panniculitis may be a useful marker of PH in patients with SSc.

Adult↗
PubMed2005

Rheumatoid factor isotypes in localized scleroderma.

Localized scleroderma is a connective tissue disorder that is sometimes accompanied by various immunological abnormalities. In this study, we analysed serum levels of rheumatoid factor (RF) isotypes in patients with localized scleroderma and in normal controls to determine if any of these isotypes reflect the severity of the disease. IgM RF, IgG RF and IgA RF were positive in 30%, 21%, and 7% of the patients, respectively. The levels of IgM RF were significantly higher in the patients with generalized morphea (GM), the most severe form of localized scleroderma, than those with linear scleroderma (LS) (P < 0.005) or normal controls (P < 0.0005). The levels of IgG RF were significantly higher in patients with GM than normal controls (P < 0.05). The levels of IgA RF were significantly higher in patients with GM or LS than normal controls (P < 0.001 and P < 0.01, respectively). The count of sclerotic lesions was significantly higher in patients with IgM RF than those without (P < 0.05). These results suggest that the presence of RF isotypes is one of the immunological abnormalities of localized scleroderma. IgM RF seemed to be most useful of these three factors to determine the severity of disease.

Adolescent↗
PubMed2004

Study of time-dependent CP violation in B0-->J/psipi0 decays.

We report a measurement of CP asymmetry parameters in the decay B0(B (0))-->J/psipi(0), which is governed by the b-->cc d transition. The analysis is based on a 140 fb(-1) data sample accumulated at the Upsilon(4S) resonance by the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. One neutral B meson in the J/psipi(0) final state is fully reconstructed for events used in this analysis. The accompanying B meson flavor is identified by its decay products. From the distribution of proper-time intervals between the two B decays, we obtain the following CP-violating parameters: S(J/psipi(0))=-0.72+/-0.42(stat)+/-0.09(syst) and A(J/psipi(0))=-0.01+/-0.29(stat)+/-0.03(syst).

Journal Article↗
PubMed2004

Observation of B+-->LambdaLambdaK+.

We report the first observation of the charmless hyperonic B decay, B+-->LambdaLambdaK+, using a 140 fb(-1) data sample recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB (e+)(e-) collider. The measured branching fraction is B(B+-->LambdaLambdaK+) = (2.91(+0.90)(-0.70) +/- 0.38) x 10(-6). We also perform a search for the related decay mode B+-->LambdaLambdapi+, but do not find a significant signal. We set a 90% confidence-level upper limit of B(B+-->LambdaLambdapi+) < 2.8 x 10(-6).

Journal Article↗
PubMed2004

Search for CP violation in the decay B0-->D*+/-D-/+.

We report a search for CP-violating asymmetry in B0-->D(*+/-)D-/+ decays. The analysis employs two methods of B0 reconstruction: full and partial. In the full reconstruction method all daughter particles of the B0 are required to be detected; the partial reconstruction technique requires a fully reconstructed D- and only a slow pion from the D(*+)-->D0pi(+)(slow) decay. From a fit to the distribution of the time interval corresponding to the distance between two B meson decay points we calculate the CP-violating parameters and find the significance of nonzero CP asymmetry to be 2.7 standard deviations.

Journal Article↗