Hachinohe National College of Technology

Silicic magmas from large caldera-forming eruptions often represent crystal-poor melts separated from highly crystalline mush zones under the influence of heat and volatiles. The cascade of magmatic processes from the formation of partially molten crustal zones to the extraction of magma from mush and its interaction with hotter intrusions creates intricate chemical zoning and textures in phenocrysts, reflecting diverse magmatic processes. Understanding the mechanisms and timescales of eruptible magma extraction and storage remains a fundamental challenge in the volcanology. To address this, we present diffusion chronometry from Fe Mg in orthopyroxenes and Ti in quartz from two Pleistocene caldera-forming eruptions at Naruko Caldera, Japan with the Nizaka (73 ka, ∼2.5 km 3 ) and Yanagisawa (45 ka, ∼10 km 3 ) Tuffs. Our findings suggest that both eruptions tapped a broadly similar crustal storage zone, but differences in extraction and localization prior to the eruption influenced the mineral assemblages (e.g., amphibole presence in Yanagisawa but not in Nizaka). Olivine and high-Mg pyroxenes, along with widespread reverse zoning, indicate significant mafic recharge during magma extraction and immediately before eruption. We propose that the Nizaka magma was physically separated from the mush, stored under cooler and less oxidized conditions, and experienced less intrusion by hot magmas, whereas the Yanagisawa magma remained in situ, forming a hotter reservoir that preserved amphibole stability. Despite these differences, the Fe Mg interdiffusion in orthopyroxenes suggests that both magmas were generated within ~300 years, with peak accumulation rates occurring within ~30 years of eruption. Ti diffusion in quartz has a shorter timescale (<30 years), capturing only the final stages of crystallization. Our results support the notion that eruptible silicic magmas might be assembled over short timescales prior to eruption regardless of their volume, which is consistent with the results of previous studies. • New petrological and mineralogical data are presented for two Pleistocene caldera eruptions at Naruko Volcano. • Magmas of both eruptions underwent different extraction and storage regimes before the eruption. • Eruptible magma bodies assembled within centuries before each eruption. • The open system processes intensified during decades before each eruption. • Diffusion modeling of orthopyroxene and quartz reveals consistent timescales.

Traditionally, synthesis of peptides using solid- or liquid-phase methods requires organic solvents, which goes against the fundamentals of green chemistry.

The evolution of Electronic Health Records (EHR) has facilitated comprehensive patient record-keeping, enhancing healthcare delivery and decision-making processes. Despite these advancements, analyzing EHR data using ensemble machine learning methods poses unique challenges. These challenges include data dimensionality, imbalanced class distributions, and the need for effective hyperparameter tuning to optimize model performance. The study conducted a thorough comparative analysis of various ensemble machine learning (EML) models using Electronic Health Record (EHR) datasets. After addressing data imbalance and reducing dimensionality, the accuracy of the EML models showed significant improvement. Notably, the Gradient Boosting Machine (GBM) and CatBoost models exhibited superior performance with an accuracy of 73%, achieved through experiments involving dimensionality reduction and handling of imbalanced data. Furthermore, optimization techniques such as Grid Search and Random Search were employed to enhance the EML models. The results of model optimization revealed that the GBM + Random Search model performed the best, achieving an accuracy of 74%, followed by the XGBoost + Grid Search model with an accuracy of 73%. The GBM model also excelled in distinguishing between positive and negative classes, boasting the highest Area under Curve (AUC) value of 0.78, indicative of its superior classification capabilities compared to other models. This study emphasizes the significance of incorporating cutting-edge EML techniques into clinical workflows and emphasizes the revolutionary potential of GBM in classification modeling for patient severity conditions. Future research should focus on deep learning (DL) applications and the integration of these models.

Chemical stimulation of geothermal reservoirs through mineral dissolution using environmentally friendly chelating agents has been suggested as a new method to complement hydraulic stimulation. However, the permeability enhancement mechanism and optimal pH remain unexplored. In this study, we conducted flooding experiments on a fractured andesitic rock at 200 °C using 20 wt% N,N-bis(carboxymethyl)-L-glutamic acid (GLDA) solution, at pH 2–10. GLDA selectively dissolved Fe-bearing minerals (e.g., pyroxenes and magnetite) under acidic conditions and quartz in the groundmass under alkaline conditions, resulting in 9.1-fold and 98-fold permeability enhancements at pH 4 and 10, respectively. Therefore, the injection of a chelating agent with different pH values based on an investigation of rock mineralogy enhanced the permeability of volcanic rocks. These findings support the feasibility and effectiveness of chemical stimulation as a viable approach for widespread global utilization for enhancing geothermal systems.

The Event Horizon Telescope (EHT) is a millimeter very long baseline interferometry (VLBI) array that has imaged the apparent shadows of the supermassive black holes M87* and Sagittarius A*. Polarimetric data from these observations contain a wealth of information on the black hole and accretion flow properties. In this work, we develop polarimetric geometric modeling methods for mm-VLBI data, focusing on approaches that fit data products with differing degrees of invariance to broad classes of calibration errors. We establish a fitting procedure using a polarimetric “m-ring” model to approximate the image structure near a black hole. By fitting this model to synthetic EHT data from general relativistic magnetohydrodynamic models, we show that the linear and circular polarization structure can be successfully approximated with relatively few model parameters. We then fit this model to EHT observations of M87* taken in 2017. In total intensity and linear polarization, the m-ring fits are consistent with previous results from imaging methods. In circular polarization, the m-ring fits indicate the presence of event-horizon-scale circular polarization structure, with a persistent dipolar asymmetry and orientation across several days. The same structure was recovered independently of observing band, used data products, and model assumptions. Despite this broad agreement, imaging methods do not produce similarly consistent results. Our circular polarization results, which imposed additional assumptions on the source structure, should thus be interpreted with some caution. Polarimetric geometric modeling provides a useful and powerful method to constrain the properties of horizon-scale polarized emission, particularly for sparse arrays like the EHT.

This paper discusses the setup of mobile components of StudyIntonation computer-assisted pronunciation training (CAPT) environment for pronunciation exercises for second language learners of Japanese. Grounded in signal processing, prosody-based speech graph visualization, and pitch quality estimation algorithms, the major focus of this contribution is on implementing the elements of multimodal pronunciation training for Japanese language, which serves as a model of a mora-timed language. We specifically address the approaches to CAPT feedback production with respect to representing mora-timed rhythmic patterns in a way that makes Japanese pronunciation training more enjoyable and more efficiently enables learners to master the mora-timed rhythm.

The dependence of the amount of power absorbed by the skin on the distance from the small antenna was analyzed based on the theory of Sommerfeld and Renner. The results showed good agreement between the theoretical and numerical values, with all power absorbed at small separation distance and converging to about 20 % at larger distance.

Background-oriented schlieren (BOS) methods is a non-contact method for visualizing fluid density fields. However, previous studies have not been applied to the visualization of natural convection boundary layers such as those formed on vertically heated walls. In this study, the possibility of the visualizing the density distribution of the natural convection boundary layer around the heating wall using the BOS method was discussed. From the experimental results, the refractive index changes along the heated plate was visualized but the further the adjustment of the camera’s focusing is required.

This paper is a continuation of work by the third author, which studied quantum walks with special long-range perturbations of the coin operator. In this paper, we consider general long-range perturbations of the coin operator and prove the non-existence of a singular continuous spectrum and embedded eigenvalues. The proof relies on the gauge transformation and construction of generalized eigenfunctions (Jost solutions) which was studied in the short-range case.