Can Reinforcement Learning Be Applied to Surgery?

Background: Remarkable progress has recently been made in the field of artificial intelligence (AI).Objective: We sought to investigate whether reinforcement learning could be used in surgery in the future.Methods: We created simple 2D tasks (Tasks 1–3) that mimicked surgery. We used a neural network library, Keras, for reinforcement learning. In Task 1, a Mac OS X with an 8 GB memory (MacBook Pro, Apple, USA) was used. In Tasks 2 and 3, a Ubuntu 14. 04LTS with a 26 GB memory (Google Compute Engine, Google, USA) was used.Results: In the task with a relatively small task area (Task 1), the simulated knife finally passed through all the target areas, and thus, the expected task was learned by AI. In contrast, in the task with a large task area (Task 2), a drastically increased amount of time was required, suggesting that learning was not achieved. Some improvement was observed when the CPU memory was expanded and inhibitory task areas were added (Task 3).Conclusions: We propose the combination of reinforcement learning and surgery. Application of reinforcement learning to surgery may become possible by setting rules, such as appropriate rewards and playable (operable) areas, in simulated tasks

Applying the Burr Type XII Distribution to Decompose Remanent Magnetization Curves

Discriminating magnetic minerals of different origins in natural samples is useful to reveal their associated geological and environmental processes, which can be achieved by the analysis of remanent magnetization curves. The analysis relies on the choice of the model distribution to unmix magnetic components. Three model distributions were proposed in past studies, namely, the lognormal, skew normal, and skewed generalized Gaussian distributions, which are related to the normal distribution. In this study, the Burr type XII distribution is tested and compared with existing model distributions. An automated protocol is proposed to assign parameters necessary to initiate the component analysis, which improves the efficiency and objectivity. Results show that the new model distribution exhibits similar flexibility to the skew normal and skewed generalized Gaussian distributions in approximating skewed coercivity distributions and can fit end‐member components better than the commonly used lognormal distribution. We demonstrate that the component analysis is sensitive to model distribution as well as measurement noise. As a consequence, the decomposition is subject to bias that is hard to identify due to the lack of ground‐truth data. It is therefore recommended to compare results derived from various model distributions to identify spurious components.This work was supported by NIPR through an Advanced Project (KP7 and KP301) and JSPS KAKENHI grants (15K13581, 16H04068, 17H06321, and 18K13638). This study was also performed under the cooperative research program of the Center for Advanced Marine Core Research, Kochi University (14A037, 14B034, 15A047, and 15B042). Z. J. acknowledges Natural Science Foundation of China (grant 41504055)

多様な地質学的背景を持つ海底熱水系の磁気的研究

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 歌田 久司, 東京大学教授 川幡 穂高, 東京大学教授 沖野 郷子, 国立極地研究所教授 野木 義史, 東京大学准教授 上嶋 誠, 東京工業大学教授 綱川 秀夫University of Tokyo(東京大学

High-resolution magnetic signature of active hydrothermal systems in the back-arc spreading region of the southern Mariana Trough

International audienceHigh-resolution vector magnetic measurements were performed on five hydrothermal vent fields of the back-arc spreading region of the southern Mariana Trough using Shinkai 6500, a deep-sea manned submersible. A new 3-D forward scheme was applied that exploits the surrounding bathymetry and varying altitudes of the submersible to estimate absolute crustal magnetization. The results revealed that magnetic-anomaly-derived absolute magnetizations show a reasonable correlation with natural remanent magnetizations of rock samples collected from the seafloor of the same region. The distribution of magnetic-anomaly-derived absolute magnetization suggests that all five andesite-hosted hydrothermal fields are associated with a lack of magnetization, as is generally observed at basalt-hosted hydrothermal sites. Furthermore, both the Pika and Urashima sites were found to have their own distinct low-magnetization zones, which could not be distinguished in magnetic anomaly data collected at higher altitudes by autonomous underwater vehicle due to their limited extension. The spatial extent of the resulting low magnetization is approximately 10 times wider at off-axis sites than at on-axis sites, possibly reflecting larger accumulations of nonmagnetic sulfides, stockwork zones, and/or alteration zones at the off-axis sites

Influence of friction stir welding conditions on joinability of oxide dispersion strengthened steel / F82H ferritic/martensitic steel joint

AbstractAs one of the joining methods for the reduced activation materials to realize the fusion reactors with high efficiency in the future, friction stir welding (FSW) is selected for fabricating the dissimilar butt joint between oxide-dispersion strengthened (ODS) alloy and F82H, and the effect of FSW conditions on joinability of this dissimilar joint was examined. The sound dissimilar joint can be produced under the condition that ODS plate is set on the advancing side and the FSW tool is plunged into F82H. As for the mild steel backside plate, the sound joint can be fabricated in the case of 150rpm rotational speed and 50mm/min traveling speed. On the other hand, by employing the silicon nitride backside plate, the total heat input should be decreased to obtain the sound joint, where the traveling speed is 100 or 150mm/min and rotational speed is 150rpm. In addition, the finite element heat conduction analyses indicate that the influence of traveling speed on the joinability with the mild steel backside plate seems to be smaller than that with the silicon nitride plate and the allowable range of the appropriate traveling speed for the joint becomes to be wider by employing the silicon nitride backside plate

Links between global magmatism and GIA -Future plan-

The Tenth Symposium on Polar Science/Special session: [S] Future plan of Antarctic research: Towards phase X of the Japanese Antarctic Research Project (2022-2028) and beyond, Tue. 3 Dec. / Entrance Hall (1st floor) at National Institute of Polar Research (NIPR

Strong ice-ocean interaction beneath Shirase Glacier Tongue in East Antarctica

Mass loss from the Antarctic ice sheet, Earth’s largest freshwater reservoir, results directly in global sea-level rise and Southern Ocean freshening. Observational and modeling studies have demonstrated that ice shelf basal melting, resulting from the inflow of warm water onto the Antarctic continental shelf, plays a key role in the ice sheet’s mass balance. In recent decades, warm ocean-cryosphere interaction in the Amundsen and Bellingshausen seas has received a great deal of attention. However, except for Totten Ice Shelf, East Antarctic ice shelves typically have cold ice cavities with low basal melt rates. Here we present direct observational evidence of high basal melt rates (7–16 m yr−1) beneath an East Antarctic ice shelf, Shirase Glacier Tongue, driven by southward-flowing warm water guided by a deep continuous trough extending to the continental slope. The strength of the alongshore wind controls the thickness of the inflowing warm water layer and the rate of basal melting

Ablation of the Ccr2 gene exacerbates polyarthritis in interleukin-1 receptor antagonist-deficient mice

金沢大学がん研究所Objective The pathogenesis of rheumatoid arthritis (RA) involves cytokines and chemokines. Given the role of intraarticular macrophage infiltration in RA, this study was undertaken to address the pathogenic role of CCR2, a chemokine receptor that is abundantly expressed by macrophages, in Il1rn-deficient mice, a mouse model of RA. Methods Il1rn-deficient and Il1rn and Ccr2-double-deficient mice were subjected to clinical assessment of arthritis and histologic examination. Bone mineral density was measured with computed tomography. The types of cells infiltrating joints were determined by immunohistochemical analysis and flow cytometric analysis. Osteoclasts in joints were quantified after tartrate-resistant acid phosphatase staining. Cytokine and chemokine levels were measured by enzyme-linked immunosorbent assay and multiplex suspension array assay. The expression patterns of chemokines and osteoclastogenic factors were determined by double-color immunofluorescence analysis. Anti-mouse CXCR2 antibody was injected into Il1rn and Ccr2-double-deficient mice for blocking experiments. Results Ablation of the Ccr2 gene actually exacerbated arthritis and intraarticular osteoclastogenesis, while it enhanced intraarticular neutrophil but not macrophage accumulation in Il1rn-deficient mice. Infiltrated neutrophils expressed the osteoclastogenic factors RANKL and ADAM-8, thereby augmenting intraarticular osteoclastogenesis in Il1rn and Ccr2-double-deficient mice. Moreover, the double-deficient mice exhibited enhanced expression of the neutrophilic chemokines keratinocyte chemoattractant and macrophage inflammatory protein 2 (MIP-2), compared with Il1rn-deficient mice. Finally, neutralizing antibodies to CXCR2, the receptor for keratinocyte chemoattractant and MIP-2, dramatically attenuated arthritis in Il1rn and Ccr2-double-deficient mice. Conclusion Our findings indicate that CCR2-mediated signals can modulate arthritis in Il1rn-deficient mice by negatively regulating neutrophil infiltration. © 2011 by the American College of Rheumatology