Controlling topological defects and contractile flow in confined nematic cell population

Topological defects in an orientation field play a vital role for controlling the collective motion of nematic cell populations within epithelia and tissue. In this study, we study the geometric control of the collective motion in a nematic cell population to further explore the interplay between topology and dynamics in active nematics. By applying spatial constraints consisting of two or three overlapping circle boundaries, we demonstrate an ordered pairing of half-integer topological defects in a confined cell population. The defects facing each other can induce a contractile cellular flow at broad geometric conditions. This robust contractile flow contributes to mechanical stimulation while altering the cell nucleus, which may be relevant to geometry-dependent morphogenesis.Comment: 8 pages, 5 figure

Current Status and Future Potential of Robotic Surgery for Gastrointestinal Cancer

　Robotic surgery has built on innovations in areas such as medical engineering and optical technology. Laparoscopic surgery has been successfully adapted for gastric, colon, and rectal cancer surgeries over the past two decades with numerous clinical trials showing oncological results comparable to those of open surgery. These trials have also shown that the laparoscopic approach shortens postoperative recovery time and decreases complication rates. Another advantage of minimally invasive techniques for the resection of gastric, colon, and rectal cancers is improved visualization of the surgical field. Despite the near absence of tactile feedback, robotic surgery has overcome many of the challenges inherent in laparoscopic surgery through features such as 3D vision, stable magnification, EndoWrist instruments, physiological tremor filtering, and motion scaling. Robotic surgery is not yet widely used in esophageal cancer surgery or in a pancreaticoduodenectomy for pancreatic cancer due to anatomical difficulties and the lack of a suitable approach.　Comparative studies of robotic and laparoscopic surgery have shown similar results in terms of perioperative management, oncologic evaluation, and functional outcomes. However, it is also true that the high cost and lack of tactile feedback in robotic surgery are major limitations in terms of current robotic technology becoming the worldwide standard for minimally invasive surgery. The future of robotic surgery will require cost reduction, the development of new platforms and technologies, the creation and validation of curricula and virtual simulators, and confirmation through appropriate randomized controlled clinical trials

Current Status and Future Potential of Robotic Surgery for Gastrointestinal Cancer

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