69 research outputs found
Incidence of sexually transmitted hepatitis C virus infection among men who have sex with men in Japan from 2009 to 2023
Although the prevalence of hepatitis C virus (HCV) infection has decreased significantly with the advent of direct-acting antiviral agents, HCV is known to spread as a sexually transmitted disease among men who have sex with men (MSM), and this study aims to provide a perspective on the future prevalence of HCV in Japan. We examined incidence in two groups of MSM with HIV attending our institution in this retrospective cohort study, from 2009 to 2019 and from 2020 to May 2023 and investigated their background factors. Twenty-two cases were newly confirmed to be HCV infection in 2009-2019 and a total of 9 cases in 2020-2023, with an incidence rate of 5.04 per 1000 person-years in 2009-2019 and 5.55 per 1000 person-years in 2020-2023. All of them were diagnosed at routine outpatient visits for HIV, and few cases were considered to have symptoms of suspected hepatitis that led to a visit to the hospital and a diagnosis of HCV. Although HCV is still prevalent among MSM in Japan, it is possible that it would not have been diagnosed without testing at regular visits as in the case of people with HIV, and that the true prevalence rate among MSM, including non-HIV-infected persons, may be much higher
Single crystal growths and magnetic properties of hexagonal polar semimetals RAuGe (R = Y, Gd-Tm, and Lu)
We study structural and magnetic properties of rare-earth based semimetals
RAuGe (R = Y, Gd-Tm, and Lu) using flux-grown single crystals. These compounds
belong to the noncentrosymmetric polar space group P63mc. We confirm the
systematic structural evolution at room temperature as a function of ionic
radius of rare earths to clarify the isopointal crossover between two polar
structures: three-dimensional LiGaGe-type and quasi-two-dimensional
NdPtSb-type. Magnetism shows a characteristic anisotropy in reasonable
agreement with the crystal electric field (CEF) theory; the easy-plane-type
anisotropy for R = Tb and Dy turns into the Ising-type anisotropy for R = Er
and Tm. We evaluate the CEF parameters based on the Stevens operators to
reasonably reproduce the temperature dependence of magnetic susceptibilities
and specific heat for RAuGe (R = Tb-Tm). The estimated energy scale of the
Ising gap (~ 11 meV) in TmAuGe is consistent with an excitation observed in an
inelastic neutron scattering experiment. These findings suggest an opportunity
for interplay between conduction electrons and nontrivial spin structures in
the family of magnetic polar semimetals RAuGe.Comment: 10 pages, 7 figures, 1 tabl
Spin excitations in optimally P-doped BaFe2(As0.7P0.3)2superconductor
We use inelastic neutron scattering to study temperature and energy
dependence of spin excitations in optimally P-doped BaFe2(As0.7P0.3)2
superconductor (Tc = 30 K) throughout the Brillouin zone. In the undoped state,
spin waves and paramagnetic spin excitations of BaFe2As2 stem from
antiferromagnetic (AF) ordering wave vector QAF= (1/-1,0) and peaks near zone
boundary at (1/-1,1/-1) around 180 meV. Replacing 30% As by smaller P to induce
superconductivity, low-energy spin excitations of BaFe2(As0.7P0.3)2form a
resonance in the superconducting state and high-energy spin excitations now
peaks around 220 meV near (1/-1,1/-1). These results are consistent with
calculations from a combined density functional theory and dynamical mean field
theory, and suggest that the decreased average pnictogen height in
BaFe2(As0.7P0.3)2 reduces the strength of electron correlations and increases
the effective bandwidth of magnetic excitations.Comment: 7 pages, 5 figures, with supplementar
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