The effects of cavitation position on the velocity of a laser-induced microjet extracted using explainable artificial intelligence

The control of the velocity of a high-speed laser-induced microjet is crucial in applications such as needle-free injection. Previous studies have indicated that the jet velocity is heavily influenced by the volumes of secondary cavitation bubbles generated through laser absorption. However, there has been a lack of investigation of the relationship between the positions of cavitation bubbles and the jet velocity. In this study, we investigate the effects of cavitation bubbles on the jet velocity of laser-induced microjets extracted using explainable artificial intelligence (XAI). An XAI is used to classify the jet velocity from images of cavitation bubbles and to extract features from the images through visualization of the classification process. For this purpose, we run 1000 experiments and collect the corresponding images. The XAI model, which is a feedforward neural network (FNN), is trained to classify the jet velocity from the images of cavitation bubbles. After achieving a high classification accuracy, we analyze the classification process of the FNN. The predictions of the FNN, when considering the cavitation positions, show a higher correlation with the jet velocity than the results considering only cavitation volumes. Further investigation suggested that cavitation that occurs closer to the laser focus position has a higher acceleration effect. These results suggest that the velocity of a high-speed microjet is also affected by the cavitation position.Comment: 11 pages, 13 figures, 4 table

Social cost of mining-related lead (Pb) pollution in Kabwe, Zambia, and potential remediation measures

Lead (Pb) pollution has been one of the major environmental problems of worldwide significance. It is a latent factor for several fatal illnesses, whereas the exposure to lead in early childhood causes a lifetime IQ loss. The social cost is the concept to aggregate various adverse effects in a single monetary unit, which is useful in describing the pollution problem and provides foundation for the design of interventions. However, the assessment of the social cost is scarce for developing countries. In this study, we focus on the lead pollution problem of a former mining town, Kabwe, Zambia, where mining wastes abandoned near residential areas has caused a critical pollution problem. We first investigated the social cost of lead pollution that future generations born in 2025–2049 would incur in their lifetime. As the channels of the social cost, we considered the lost income from the IQ loss and the lost lives from lead-related mortality. The results showed that the social cost would amount to 224–593 million USD (discounted to the present value). Our results can be considered conservative, lower bound estimates because we focused only on well-identified effects of lead, but the social cost was still substantial. Then we examined several engineering remediation measures. The results showed that the social cost can be reduced (the benefits of remediations) more than the costs of implementing remediation measures. This study is the first to investigate the social cost of mining-related lead pollution problem in developing countries. Our interdisciplinary approach utilises the micro-level economic, health and pollution data and integrates the techniques in economics, toxicology and engineering.publishedVersio

Rate of oral frailty and oral hypofunction in rural community-dwelling older Japanese individuals

Objective To clarify the rate of oral frailty and oral hypofunction in rural community-dwelling older adults in Japan. Background Recently, the oral function of Japanese older adults has been evaluated multilaterally based on two concepts: oral frailty and oral hypofunction. Oral frailty is defined as a decrease in the oral function accompanied by a decrease in mental and physical functions. Oral hypofunction is a disease where the oral function is comprehensively decreased. However, their rates have not yet been elucidated. Materials and methods Oral frailty and oral hypofunction were evaluated in 679 older adults from rural areas. To investigate the differences in occurrence rates due to the evaluation methods, one of the subordinate symptoms of oral hypofunction, the reduced occlusal force, was evaluated based on both the occlusal force (main method) and the number of teeth (alternative method). Results The rate of oral frailty was 22.3% in men and 22.7% in women. The rate of oral hypofunction was 39.0% in men and 46.9% in women. The overall rate of oral hypofunction was 43.6% when the reduced occlusal force of oral hypofunction was evaluated using the main method and 46.4% when evaluated using the alternative method. The proportion of participants with decreased occlusal force, the number of present teeth, oral diadochokinesis, tongue pressure and masticatory performance increased with age in both men and women. Conclusion Among rural community-dwelling older adults, the rate of oral frailty was 22.5% and that of oral hypofunction was 43.6%

Factors associated with masticatory performance in community-dwelling older adults A cross-sectional study

Background. Decreased masticatory performance leads to deterioration of overall health among older adults. However, maintaining and improving masticatory performance in ways other than maintenance of natural teeth and appropriate prosthodontic treatment remains unclear. If the factors related to the mixing and shearing abilities for masticatory performance are clarified, it may be possible to maintain and improve the masticatory performance of older adults. We aimed to clarify the association among mixing ability, shearing ability, and masticatory performance-related factors. Methods. Of the 707 community-dwelling older adults in Kusatsu Town, Japan, 344 who had been treated for any dental defects were enrolled in this study. Masticatory performance was evaluated on the basis of mixing ability and shearing ability. The number of natural teeth and artificial teeth, occlusal force, tongue pressure, and oral diadochokinesis /ta/ were measured as masticatory performance-related factors. Their relationship with mixing ability, shearing ability, and masticatory performance-related factors was examined by means of Spearman rank correlation coefficient and path analysis. Results. Among masticatory performance-related factors, the number of natural teeth, occlusal force, and tongue pressure were directly associated with both mixing ability and shearing ability. Moreover, mixing ability was also directly associated with shearing ability. Conclusions. Tongue pressure, which can be improved by means of training, is a masticatory performance-related factor associated with both mixing and shearing abilities

Preferential Expression of Ca2+-Stimulable Adenylyl Cyclase III in the Supraventricular Area, including Arrhythmogenic Pulmonary Vein of the Rat Heart

Ectopic excitability in pulmonary veins (PVs) is the major cause of atrial fibrillation. We previously reported that the inositol trisphosphate receptor in rat PV cardiomyocytes cooperates with the Na+-Ca2+ exchanger to provoke ectopic automaticity in response to norepinephrine. Here, we focused on adenylyl cyclase (AC) as another effector of norepinephrine stimulation. RT-PCR, immunohistochemistry, and Western blotting revealed that the abundant expression of Ca2+-stimulable AC3 was restricted to the supraventricular area, including the PVs. All the other AC isotypes hardly displayed any region-specific expressions. Immunostaining of isolated cardiomyocytes showed an enriched expression of AC3 along the t-tubules in PV myocytes. The cAMP-dependent response of L-type Ca2+ currents in the PV and LA cells is strengthened by the 0.1 mM intracellular Ca2+ condition, unlike in the ventricular cells. The norepinephrine-induced automaticity of PV cardiomyocytes was reversibly suppressed by 100 µM SQ22536, an adenine-like AC inhibitor. These findings suggest that the specific expression of AC3 along t-tubules may contribute to arrhythmogenic automaticity in rat PV cardiomyocytes

Prediction of the morphological evolution of a splashing drop using an encoder–decoder

The impact of a drop on a solid surface is an important phenomenon that has various implications and applications. However, the multiphase nature of this phenomenon causes complications in the prediction of its morphological evolution, especially when the drop splashes. While most machine-learning-based drop-impact studies have centred around physical parameters, this study used a computer-vision strategy by training an encoder–decoder to predict the drop morphologies using image data. Herein, we show that this trained encoder–decoder is able to successfully generate videos that show the morphologies of splashing and non-splashing drops. Remarkably, in each frame of these generated videos, the spreading diameter of the drop was found to be in good agreement with that of the actual videos. Moreover, there was also a high accuracy in splashing/non-splashing prediction. These findings demonstrate the ability of the trained encoder–decoder to generate videos that can accurately represent the drop morphologies. This approach provides a faster and cheaper alternative to experimental and numerical studies

Myofibroblast β2 adrenergic signaling amplifies cardiac hypertrophy in mice

Abnormal β-adrenergic signaling plays a central role in human heart failure. In mice, chronic β-adrenergic receptor (βAR) stimulation elicits cardiac hypertrophy. It has been reported that cultured cardiac fibroblasts express βAR; however, the functional in vivo requirement of βAR signaling in cardiac fibroblasts during the development of cardiac hypertrophy remains elusive. β2AR null mice exhibited attenuated hypertrophic responses to chronic βAR stimulation upon continuous infusion of an agonist, isoprenaline (ISO), compared to those in wildtype controls, suggesting that β2AR activation in the heart induces pro-hypertrophic effects in mice. Since β2AR signaling is protective in cardiomyocytes, we focused on β2AR signaling in cardiac myofibroblasts. To determine whether β2AR signaling in myofibroblasts affects cardiac hypertrophy, we generated myofibroblast-specific transgenic mice (TG) with the catalytic subunit of protein kinase A (PKAcα) using Cre-loxP system. Myofibroblast-specific PKAcα overexpression resulted in enhanced heart weight normalized to body weight ratio, associated with an enlargement of cardiomyocytes at 12 weeks of age, indicating that myofibroblast-specific activation of PKA mediates cardiac hypertrophy in mice. Neonatal rat cardiomyocytes stimulated with conditioned media from TG cardiac fibroblasts likewise exhibited significantly more growth than those from controls. Thus, β2AR signaling in myofibroblasts plays a substantial role in ISO-induced cardiac hypertrophy, possibly due to a paracrine effect. β2AR signaling in cardiac myofibroblasts may represent a promising target for development of novel therapies for cardiac hypertrophy