Stability of boundary element methods for the two dimensional wave equation in time domain revisited

This study considers the stability of time domain BEMs for the wave equation in 2D. We show that the question of stability of time domain BEMs is reduced to a nonlinear eigenvalue problem related to frequency domain integral equations. We propose to solve this non-linear eigenvalue problem numerically with the Sakurai-Sugiura method. After validating this approach numerically in the exterior Dirichlet problem, we proceed to transmission problems in which we find that some time domain counterparts of “resonance-free” integral equations in frequency domain lead to instability. We finally show that the proposed stability analysis helps to reformulate these equations to obtain stable numerical schemes

Arabidopsis ECHIDNA protein is involved in seed coloration, protein trafficking to vacuoles, and vacuolar biogenesis

Flavonoids are a major group of plant-specific metabolites that determine flower and seed coloration. In plant cells, flavonoids are synthesized at the cytosolic surface of the endoplasmic reticulum and are sequestered in the vacuole. It is possible that membrane trafficking, including vesicle trafficking and organelle dynamics, contributes to flavonoid transport and accumulation. However, the underlying mechanism has yet to be fully elucidated. Here we show that the Arabidopsis ECHIDNA protein plays a role in flavonoid accumulation in the vacuole and protein trafficking to the vacuole. We found defective pigmentation patterns in echidna seed, possibly caused by reduced levels of proanthocyanidins, which determine seed coloration. The echidna mutant has defects in protein sorting to the protein storage vacuole as well as vacuole morphology. These findings indicate that ECHIDNA is involved in the vacuolar trafficking pathway as well as the previously described secretory pathway. In addition, we found a genetic interaction between echidna and green fluorescent seed 9 (gfs9), a membrane trafficking factor involved in flavonoid accumulation. Our findings suggest that vacuolar trafficking and/or vacuolar development, both of which are collectively regulated by ECHIDNA and GFS9, are required for flavonoid accumulation, resulting in seed coat pigmentation

Observations of High Energy Cosmic-Ray Electrons from 30 GeV to 3 TeV with Emulsion Chambers

We have performed a series of cosmic-ray electron observations using the balloon-borne emulsion chambers since 1968. While we previously reported the results from subsets of the exposures, the final results of the total exposures up to 2001 are presented here. Our successive experiments have yielded the total exposure of 8.19 m^2 sr day at the altitudes of 4.0 - 9.4 g/cm^2. The performance of the emulsion chambers was examined by accelerator beam tests and Monte-Carlo simulations, and the on-board calibrations were carried out by using the flight data. In this work we present the cosmic-ray electron spectrum in the energy range from 30 GeV to 3 TeV at the top of the atmosphere, which is well represented by a power-law function with an index of -3.28+-0.10. The observed data can be also interpreted in terms of diffusive propagation models. The evidence of cosmic-ray electrons up to 3 TeV suggests the existence of cosmic-ray electron sources at distances within ~1 kpc and times within ~1x10^5 yr ago.Comment: 38 pages, 10 figures, 3 tables, Accepted for publication in Ap

太陽光中のUVA/UVBの比率の季節差がDNA損傷（6-４）型光産物のDewar型光産物への光異性化の効率に影響を及ぼす

The UVA and UVB components of sunlight can produce three classes of bipyrimidine DNA photolesions [cyclobutane pyrimidine dimers (CPDs), pyrimidine (6-4) pyrimidone photoproducts (6-4PPs) and related Dewar valence isomers (DewarPPs)]. The UVA/UVB ratio of sunlight is high in winter and low in summer in the Northern Hemisphere. Since UVB radiation produces 6-4PPs and UVA radiation converts them into DewarPPs through photoisomerization, it is expected that there may be differences in the photoisomerization of 6-4PPs between summer and winter, although that has never been documented. To determine that, isolated DNA was exposed to natural sunlight for 8 h in late summer and in winter, and absolute levels of the three classes of photolesions were quantified using calibrated ELISAs. It was found that sunlight produces CPDs and 6-4PPs in DNA at a ratio of about 9:1 and converts approximately 80% of 6-4PPs into DewarPPs within 3 h. Moreover, photoisomerization is more efficient in winter than in late summer after sunlight irradiation for the same duration, at similar solar UV doses and with the same induction level of CPDs. These results demonstrate that seasonal differences in the UVA/UVB ratio influence the efficiency of the photoisomerization of 6-4PPs into DewarPPs.博士（医学）・甲第775号・令和3年3月15日© 2020 The Authors. Photochemistry and Photobiology published by Wiley Periodicals LLC on behalf of American Society for Photobiology. This is an open access article under the terms of the Creative Commons Attribution License(https://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited

The Relationship between Inferior Vena Cava Distensibility and Arterial Blood Pressure

The purpose of this study was to clarify the relationship between the inferior vena cava distensibility and blood pressure. Six Japanese healthy males volunteered to participate in this study. We measured the cross-sectional area of inferior vena cava (CSAivc) and blood pressure at rest and during passive leg raising in supine position. We calculated the change rates of each parameter, based on the value at rest in supine position. We observed a negative correlation between the change rate of CSAivc and systolic blood pressure (P<0.05). These results suggest that the inferior vena cava distensibility affects partially systolic blood pressure

Effects of Eating or Skipping Breakfast on Heart Rate and Oxygen Uptake

The purpose of this study was to compare changes in heart rate, oxygen uptake, blood pressure and oral temperature between subjects eating breakfast and subjects skipping breakfast when they exercise each day at 11:00 AM and 2:00 PM. The study design included two different groups, a breakfast group and a skipping group. Subjects rested for five minutes, and they exercised on a pendulum ergometer for twenty minutes. After exercising, the resistance was returned to zero for a one minute cool down followed by five more minutes of complete rest(recovery phase). Oral temperatures of the skipping group were lower than those of the breakfast group at 11:00 AM. Diet induced thermogenesis (DIT), which increases core body temperature, is generated by eating breakfast. In the skipping group, the resting heart rates at 11:00 AM were lower than at 2:00 PM. A significant difference in heart rate after the first minute of exercise was seen between 11:00 AM and 2:00 PM in the skipping group. These results suggested that when skipping breakfast, the heart rate response immediately after beginning exercise is slow in the morning. Although all subjects did cooling down for one minute after exercising, oxygen uptake during the recovery phase in the skipping group at 11:00 AM was significantly higher than at rest. These results suggest that eating breakfast has a physiological influence on both heart rate and oxygen uptake

Interest in Infectious Diseases specialty among Japanese medical students amidst the COVID-19 pandemic: A web-based, cross-sectional study

IntroductionThe emergence of the novel coronavirus disease of 2019 (COVID-19) has led to huge disruptions in the medical field and society. The significance of training and education for experts has been increasingly acknowledged in Japan, where the number of infectious disease (ID) specialists is reportedly insufficient. In this paper, we report the results of a web-based survey that was conducted to reveal the ways in which the COVID-19 pandemic has influenced medical students' awareness of ID specialists and future career choices. MethodThis cross-sectional descriptive study was conducted in March 2021 and targeted 717 medical students belonging to Medical School of Okayama University, Japan. The questionnaire consisted of four questions meant to assess students' knowledge and future intentions of becoming ID specialists. ResultsWe obtained 328 eligible questionnaires (response rate: 45.7%). Of 227 (69.2%) students who were aware of ID specialists, 99 (43.6%) answered that they came to know about them only after the pandemic, 12 (3.7%) answered that their interest in being an ID specialist arose during the pandemic, while 36 (11.0%) responded that they would rather not become ID specialists. At the time of the survey, 5 students (1.5%) were aiming to become ID specialists. ConclusionWe observed a very low rate of interest to be an ID specialist among medical students. The experience of the pandemic does not seem to have influenced Japanese medical students to choose ID as a specialty for their careers. Continuous efforts to increase the number of ID specialists are necessary in Japan as a countermeasure against the coming pandemic

Impact of the COVID-19 Pandemic on the Psychological Distress of Medical Students in Japan: Cross-sectional Survey Study

Background: The COVID-19 pandemic has negatively affected medical education. However, little data are available about medical students’ distress during the pandemic. Objective: This study aimed to provide details on how medical students have been affected by the pandemic. Methods: A cross-sectional study was conducted. A total of 717 medical students participated in the web-based survey. The survey included questions about how the participants’ mental status had changed from before to after the Japanese nationwide state of emergency (SOE). Results: Out of 717 medical students, 473 (66.0%) participated in the study. In total, 29.8% (141/473) of the students reported concerns about the shift toward online education, mostly because they thought online education would be ineffective compared with in-person learning. The participants’ subjective mental health status significantly worsened after the SOE was lifted (P Conclusions: Given our findings, the sudden shift to online education might have overwhelmed medical students. Thus, we recommend that educators inform learners that online learning is not inferior to in-person learning, which could attenuate potential depression and anxiety