Hirohito Yamazaki

Bio: Hirohito Yamazaki is an academic researcher from Tohoku University. The author has contributed to research in topics: Meson & Pion. The author has an hindex of 17, co-authored 74 publications receiving 1004 citations. Previous affiliations of Hirohito Yamazaki include KEK.

Photoproduction of η mesons off protons for E γ ⩽1.15 GeV

Abstract: \ensuremath{\eta} mesons emitted from the photoproduction off protons were measured for $0.70\ensuremath{\leqslant}{E}_{\ensuremath{\gamma}}\ensuremath{\leqslant}1.15$ GeV. The $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\eta}p$ reaction process was separated from the $\ensuremath{\pi}\ensuremath{\eta}p$ final state by the momentum difference of \ensuremath{\eta} mesons for ${E}_{\ensuremath{\gamma}}\ensuremath{\geqslant}930$ MeV. The angular distributions obtained and the excitation function of the $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\eta}p$ reaction are essentially in good agreement with previously reported ones and are well explained by \ensuremath{\eta}-MAID calculations. For the $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\eta}N$ reaction, the cross section increases monotonically with increasing photon energy, and it almost reaches the value of the $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\eta}p$ reaction at ${E}_{\ensuremath{\gamma}}~1.15$ GeV. The momentum distributions are compared with kinematic calculations. It is suggested that the sequential decay process through the ${P}_{33}$(1232) resonance [$\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\eta}{P}_{33}(1232)\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\eta}N$] contributes to the $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\eta}N$ reaction, in addition to the sequential process $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\pi}{S}_{11}(1535)\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\eta}N$ and/or \ensuremath{\pi} and \ensuremath{\eta} emissions without intermediate nucleon resonances.

High incidence of cytomegalovirus reactivation in adult recipients of an unrelated cord blood transplant

Abstract: This retrospective analysis of cytomegalovirus (CMV)-seropositive adult transplant recipients showed that CMV antigenemia occurred after transplantation in 10/10 (100%) recipients of unrelated cord blood, 17/39 (43%) recipients of a related matched donor graft, 16/23 (79%) recipients of an unrelated matched donor graft, and 8/12 (67%) recipients of a mismatched related donor graft. These results suggest that unrelated cord blood transplantation itself may be correlated with a high incidence of CMV reactivation.

Narrow Resonance at Eγ = 1020 MeV in the D(γ,η)pn Reaction

Abstract: Differential and total cross sections of the D(γ, η)pn reaction have been measured for photon energies between 600 and 1150 MeV. The data provide the information of the γn → ηn reaction above Eγ ≥ 800 MeV. The total cross section shows a narrow resonance structure peaked at Eγ = 1020 MeV. The angular distribution coefficients together with the total cross section are compared with the calculation of the isobar model by using the impulse approximation. Although the spin and parity of the resonance cannot be determined unambiguously, a negative parity assignment gives better fit to the data.

Bremsstrahlung in α Decay of 210 Po: Do α Particles Emit Photons in Tunneling?

Abstract: Emission probability of bremsstrahlung in the {alpha} decay of {sup 210}Po was measured in {alpha} -{gamma} coincidence measurements with Si and Ge detectors. It was found that the bremsstrahlung yields are much smaller than those predicted by a Coulomb acceleration model, in which {gamma} rays are emitted during acceleration outside the barrier. This suggests that the radiation amplitude in the barrier cannot be neglected, and the discussion based on a quasiclassical approach is given. {copyright} {ital 1997} {ital The American Physical Society}

Chiral symmetry restoration and dileptons in relativistic heavy ion collisions

Abstract: The current theoretical status in the analysis and interpretation of low-mass dilepton measurements in (ultra-) relativistic heavy-ion experiments is reviewed. Special emphasis is put on potential signals of (partial) restoration of dynamically broken chiral symmetry in a hot and dense hadronic medium. It follows from chiral symmetry alone that parity partners of hadronic correlation functions must become identical when the symmetry is restored. The assessment of medium effects in the vector channel, which governs the dilepton production, thus necessitates a simultaneous treatment of the vector and axialvector degrees of freedom. While significant progress in this respect has been made some open questions remain in establishing a rigorous link in the mass region below 1 GeV. From the present calculations a suggestive 'quark-hadron duality' emerges near the phase boundary. It implies substantial medium effects in the dilepton signal from the hadronic phase which smoothly matches a perturbative description within the plasma phase.

Guidelines for the diagnosis and management of aplastic anaemia

Abstract: King’s College Hospital, St Mary’s Hospital, Barts and The London Hospital, London, Birmingham Children’s Hospital, Birmingham, Barts and The London School of Medicine and Dentistry, St George’s Hospital, London, Queen Elizabeth Hospital, King’s Lynn, Norfolk, Ashford Hospital, Middlesex, London, Patient representative, St Helier Hospital, Carshalton, Surrey, Royal Bournemouth Hospital, Dorset, Chesterfield Royal Hospital, Derbyshire, and Manchester Royal Infirmary, Manchester, UK.