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Leonardo da Vinci is usually credited with conducting the first systematic study of friction in the late 15th century, a subfield now known as tribology that deals with the dynamics of interacting surfaces in relative motion. Da Vinci's notebooks depict how he pulled rows of blocks using weights and pulleys, an approach that is still used in frictional studies today, as well as examining the friction produced in screw threads, wheels, and axles. The authors of this latest paper used an experimental setup similar to da Vinci's.
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2. 运输和导航：医院校园面积大，志愿者会驾驶高尔夫球车，接送患者、访客和员工，帮老人减少步行负担，避免迷路——这对行动不便的老年患者来说，格外实用。
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