Insights from the magnetic field dependence of the muonium-to-antimuonium transition

The muonium-to-antimuonium transition experiment is about to be updated. Notably, the experiment at J-PARC in Japan can explore the magnetic field dependence of the transition probability. In this paper, we investigate the information that we can extract from the transition probabilities across different magnetic field strengths, while also taking into account a planned transition experiment at CSNS in China. There are two model-independent parameters in the transition amplitude, and we ascertain the feasibility of determining these parameters, including their relative physical phase, from experimental measurements. This physical phase can be related to the electron electric dipole moment, which is severely constrained by experiments. The underlying mediator responsible for the transition can be either doubly charged particles or neutral particles. In the former case, typical magnetic fields yield specific probability ratios, while the latter presents a range of the probability ratio. We investigate several models with neutral mediators, and elucidate that the probability ratio is linked to the sign of new physics contribution to the electron $g-2$. The pivotal role of the J-PARC transition experiment in shedding light on these insights is emphasized.Comment: 33 pages, 14 figure

Neutrinoless double beta decay and the muonium-to-antimuonium transition in models with a doubly charged scalar

The lepton number and flavor violations are important possible ingredients of the lepton physics. The neutrinoless double beta decay and the transition of the muonium into antimuonuim are related to those violations. The former can give us an essential part of fundamental physics, and there are plenty of experimental attempts to observe the process. The latter has also been one of the attractive phenomena, and the experimental bound will be updated in planned experiments at new high-intensity muon beamlines. In models with a doubly charged scalar, not only can those two processes be induced, but also the active neutrino masses can be induced radiatively. The flavor violating decays of the charged leptons constrain the flavor parameters of the models. We study how the muonium-to-antimuonium transition rate can be as large as the current experimental bound, and we insist that the updated bound of the transition rate will be useful to distinguish the models to generate the neutrinoless double beta decay via the doubly charged scalar. We also study a possible extension of the model to the left-right model which can induce the neutrinoless double beta decay.Comment: 38 pages, 13 figures; note adde

Successful management of placenta percreta by cesarean hysterectomy with transverse uterine fundal incision

Placenta accreta presents one of the highest risks to pregnancy, and its more severe variant, placenta percreta, is particularly risky. The incidence of both conditions is increasing. Placenta percreta requires a cesarean hysterectomy for management, but the challenges associated with this surgery often result in severe obstetric hemorrhaging and high rates of maternal morbidity. Several recent obstetric studies have reported on the usefulness of the transverse uterine fundal incision for the management of placenta accreta and its variants. However, these reports included only a few cases of placenta percreta. Here we present a case of placenta percreta covering the anterior uterine wall that was successfully managed using a transverse fundal incision, which avoided incising the placenta at delivery and thus reduced maternal blood loss. After delivery, the patient underwent a total abdominal hysterectomy without the need for a blood transfusion. We conclude that a transverse uterine fundal incision can be very useful for the management of placenta percreta of the anterior uterine wall

Modeling SARS-CoV-2 infection and its individual differences with ACE2-expressing human iPS cells

ACE発現ヒトiPS細胞を用いたSARS-CoV-2感染の個人差再現と原因究明. 京都大学プレスリリース. 2021-04-19.Stem cells show gender differences in COVID-19 risk. 京都大学プレスリリース. 2021-04-19.Genetic differences are a primary reason for differences in the susceptibility and severity of COVID-19. As induced pluripotent stem (iPS) cells maintain the genetic information of the donor, they can be used to model individual differences in SARS-CoV-2 infection in vitro. We found that human iPS cells expressing the SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) (ACE2-iPS cells) can be infected w SARS-CoV-2. In infected ACE2-iPS cells, the expression of SARS-CoV-2 nucleocapsid protein, budding of viral particles, and production of progeny virus, double membrane spherules, and double-membrane vesicles were confirmed. We performed SARS-CoV-2 infection experiments on ACE2-iPS/ embryonic stem (ES) cells from eight individuals. Male iPS/ES cells were more capable of producing the virus compared with female iPS/ES cells. These findings suggest that ACE2-iPS cells can not only reproduce individual differences in SARS-CoV-2 infection in vitro but also are a useful resource to clarify the causes of individual differences in COVID-19 due to genetic differences

Atomic-scale flattening of SiC surfaces by electroless chemical etching in HF solution with Pt catalyst

The authors present a method for flattening SiC surfaces with Pt as a catalyst in HF solution. The mechanism for flattening SiC surfaces is discussed. The flattened 4H-SiC (0001) surface is composed of alternating wide and narrow terraces with single-bilayer-height steps, which are induced by the rate difference of the catalytic reactions between adjacent terraces. Scanning tunneling microscopy images reveal a 1×1 phase on the terraces. The 1×1 phase is composed of coexisting of F- and OH-terminated Si atoms, which originate from the polarization of the underlying Si-C bonds. © 2007 American Institute of Physics.Kenta Arima, Hideyuki Hara, et al. "Atomic-scale flattening of SiC surfaces by electroless chemical etching in HF solution with Pt catalyst", Appl. Phys. Lett. 90(20), 202106 (2007) https://doi.org/10.1063/1.2739084