The Technical Design for the COMET Phase-I experiment is presented in this paper. COMET is an experiment at J-PARC, Japan, which will search for neutrinoless conversion of muons into electrons in the field of an aluminum nucleus ($\mu$–$e$ conversion, $\mu^{-}N \rightarrow e^{-}N$); a lepton flavor-violating process. The experimental sensitivity goal for this process in the Phase-I experiment is $3.1\times10^{-15}$, or 90% upper limit of a branching ratio of $7\times 10^{-15}$, which is a factor of 100 improvement over the existing limit. The expected number of background events is 0.032. To achieve the target sensitivity and background level, the 3.2 kW 8 GeV proton beam from J-PARC will be used. Two types of detectors, CyDet and StrECAL, will be used for detecting the $\mu$–$e$ conversion events, and for measuring the beam-related background events in view of the Phase-II experiment, respectively. Results from simulation on signal and background estimations are also described.

Laser-driven expansion of pure-tin microdroplets was demonstrated to produce an efficient and low-debris extreme-ultraviolet (EUV) light source. The pre-expansion is indispensable for resolving the considerable mismatch between the optimal laser spot diameter (∼300μm) and the diameter (∼20μm) of microdroplets containing the minimum-mass Sn fuel for generating the required EUV radiant energy (∼10mJ/pulse). Explosive expansion of microdroplets was attained by using a laser prepulse, whose intensity was at least 3×1011W∕cm2. The expanded microdroplet was irradiated with a CO2 laser pulse to generate EUV light. A combination of low density and long-scale length of the expanded microdroplet leads to a higher EUV energy conversion efficiency (4%) than that (2.5%) obtained from planar Sn targets irradiated by a single CO2 laser pulse. This scheme can be used to produce a practical EUV light source system.

This study aimed to assess the effects of a multicomponent exercise program on physical function and muscle mass in older adults with sarcopenia or pre-sarcopenia. Moreover, we aim to standardize the exercise program for easy incorporation in the daily life of community-dwelling older adults as a secondary outcome. A single-blind randomized controlled trial was conducted with individuals (≥60 years) who had sarcopenia or pre-sarcopenia (n = 72). Participants were randomly assigned to the exercise and control groups. The exercise program consisted of 12 weekly 60-min sessions that included resistance, balance, flexibility, and aerobic training. Outcome measures were physical function and muscle mass. Assessments were conducted before and immediately after the intervention. Among the 72 participants (mean age: 75.0 ± 6.9 years; 70.8% women), 67 (93.1%) completed the trial. Group-by-time interactions on the chair stand (p = 0.02) and timed “up and go” (p = 0.01) tests increased significantly in the exercise group. Although the exercise group showed a tendency to prevent loss of muscle mass, no significant interaction effects were observed for cross-sectional muscle area and muscle volume. The 12-week exercise program improved physical function in the intervention group. Although it is unclear whether the program is effective in increasing muscle mass, a multicomponent exercise program would be an effective treatment for physical function among older adults with sarcopenia.

This cross-sectional study investigated the association between chronic pain and physical frailty in community-dwelling older adults. We analyzed data obtained from 323 older adults (women: 74.6%) who participated in a community-based health check survey (the Tarumizu Study, 2017). Physical frailty was defined in terms of five parameters (exhaustion, slowness, weakness, low physical activity, and weight loss). We assessed the prevalence of chronic low back and knee pain using questionnaires. Participants whose pain had lasted ≥two months were considered to have chronic pain. Among all participants, 138 (42.7%) had chronic pain, and 171 (53.0%) were categorized as having physical frailty or pre-frailty. Logistic regression analysis showed that chronic pain was significantly associated with the group combining frailty and pre-frailty (odds ratio 1.68, 95% confidence interval 1.03–2.76, p = 0.040) after adjustment for age, sex, body mass index, score on the 15-item Geriatric Depression Scale, and medications. Comparing the proportions of chronic pain among participants who responded to the sub-items, exhaustion (yes: 65.9%, no: 39.4%) demonstrated a significant association (p < 0.001). Chronic pain could be associated with the group combining frailty and pre-frailty and is particularly associated with exhaustion in community-dwelling older adults. Therefore, there is a need for early intervention and consideration of the role of exhaustion when devising interventions for physical frailty in older individuals with chronic pain.

The aim of this systematic review and meta-analyses was to calculate the pooled prevalence of sarcopenia based on the Asia Working Group for Sarcopenia (AWGS) criteria among Japanese communitydwelling older adults. Data from 8 studies were used to determine the prevalence of sarcopenia in the overall population and in men; data from 9 studies were used to determine that of women. The pooled prevalence rates of sarcopenia using random-effects models were 9.9% (95% confidence interval [CI], 6.2%-15.4%) overall; 9.8% (95% CI, 6.2%-15.2%) among men; and 10.1% (95% CI, 6.4%-15.5%) among women. These findings would be useful to inform community-based strategies and advanced research addressing sarcopenia prevention.