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Combinatorial optimization to search for the best solution across a vast number of legal candidates requires the development of a domain-specific computing architecture that can exploit the computational power of physical processes, as conventional general-purpose computers are not powerful enough. Recently, Ising machines that execute quantum annealing or related mechanisms for rapid search have attracted attention. These machines, however, are hard to map application problems into their architecture, and often converge even at an illegal candidate. Here, we demonstrate an analogue electronic computing system for solving the travelling salesman problem, which mimics efficient foraging behaviour of an amoeboid organism by the spontaneous dynamics of an electric current in its core and enables a high problem-mapping flexibility and resilience using a resistance crossbar circuit. The system has high application potential, as it can determine a high-quality legal solution in a time that grows proportionally to the problem size without suffering from the weaknesses of Ising machines.

We investigate the effect of asymmetric deformation dynamics in an amoeboid organism on its search ability using a model amoeba. The model represents the behaviours of the amoeboid organism and its search ability is evaluated by searching for the solution to a Boolean satisfiability problem (SAT). We found that the efficiency of the search is significantly improved by implementing asymmetric delays in response to the feedback signals that increase and decrease the variable under appropriate errors. The results indicate that the model could search around the variable vector space by means of the appropriate combination of the inherent local search in the model and the error-induced global search. The results also show that the asymmetric response delays bias the variable to the values that can satisfy the SAT. We also demonstrate that an analog electronic system implementing the amoeba model with asymmetric dynamics possesses the search characteristics of the model.

Background: Glissonean pedicle isolation is a very useful procedure during a laparoscopic anatomic hepatectomy (LAH); however, few studies have reported the precise layer structure around a Glissonean pedicle. The aim of this study was to evaluate the layer structure around a Glissonean pedicle in cadaveric models and determine whether Glissonean pedicle isolation based on the layer structure can serve as a standard surgical procedure during a LAH. Methods: From April 2017 to December 2019, LAHs were performed in 59 patients. Prior to the LAH, a cadaveric model was used to verify the layer structure around the Glissonean pedicle. The procedure was also performed in live patients during LAHs and pathologic verification was performed. In addition, we evaluated the short-term results of LAHs. Results: Laennec's capsule covering the liver parenchyma was shown by histologic examination (Elastica van Gieson staining) in a cadaveric model and live patients. The gap between the Glissonean pedicle and Laennec's capsule was dissected without parenchymal destruction. A LAH based on cadaver simulation had an operative time of 398 min and blood loss of 142 ml. Post-operative complications occurred in 2 patients (3%), and there were no mortalities. The length of hospital stay was 13 days. Conclusion: There is a layer structure around the Glissonean pedicle; it is necessary to recognize Laennec's capsule as a landmark. When performing Glissonean pedicle isolation, it is possible to perform a safer and more precise LAH by placing importance on Laennec's capsule.