摘要翻译：
许多泌尿学研究依赖于动物模型，如大鼠和猪，它们的排尿物理和与人类的相关性知之甚少。在这里，我们阐明了在动物质量的五个数量级上排尿的流体力学。利用亚特兰大动物园的高速视频和流量测量，我们发现了“排尿定律”，即动物在几乎恒定的平均21秒（标准差13秒）内排空膀胱。这一壮举是因为较大的动物有较长的尿道，从而更高的重力和流速。较小的哺乳动物在排尿时受到挑战，因为高粘性和表面张力限制了它们的尿液只能滴一滴。我们的发现揭示了尿道构成了一个流动增强装置，使泌尿系统能够在不损害其功能的情况下扩大规模。这项研究可能有助于诊断动物的泌尿系统问题，并启发设计基于自然界的可伸缩流体动力系统。
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英文标题：
《Law of Urination: all mammals empty their bladders over the same
  duration》
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作者：
Patricia J. Yang, Jonathan C. Pham, Jerome Choo and David L. Hu
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最新提交年份：
2014
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分类信息：

一级分类：Physics        物理学
二级分类：Fluid Dynamics        流体动力学
分类描述：Turbulence, instabilities, incompressible/compressible flows, reacting flows. Aero/hydrodynamics, fluid-structure interactions, acoustics. Biological fluid dynamics, micro/nanofluidics, interfacial phenomena. Complex fluids, suspensions and granular flows, porous media flows. Geophysical flows, thermoconvective and stratified flows. Mathematical and computational methods for fluid dynamics, fluid flow models, experimental techniques.
湍流，不稳定性，不可压缩/可压缩流，反应流。气动/流体力学，流体-结构相互作用，声学。生物流体力学，微/纳米流体力学，界面现象。复杂流体，悬浮液和颗粒流，多孔介质流。地球物理流，热对流和层流。流体动力学的数学和计算方法，流体流动模型，实验技术。
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一级分类：Quantitative Biology        数量生物学
二级分类：Other Quantitative Biology        其他定量生物学
分类描述：Work in quantitative biology that does not fit into the other q-bio classifications
不适合其他q-bio分类的定量生物学工作
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英文摘要：
  Many urological studies rely upon animal models such as rats and pigs whose urination physics and correlation to humans are poorly understood. Here we elucidate the hydrodynamics of urination across five orders of magnitude in animal mass. Using high-speed videography and flow rate measurement at Zoo Atlanta, we discover the "Law of Urination," which states animals empty their bladders over nearly constant duration of average 21 seconds (standard deviation 13 seconds). This feat is made possible by larger animals having longer urethras, thus higher gravitational force and flow speed. Smaller mammals are challenged during urination due to high viscous and surface tension forces that limit their urine to single drops. Our findings reveal the urethra constitutes as a flow enhancing device, enabling the urinary system to be scaled up without compromising its function. This study may help in the diagnosis of urinary problems in animals and in inspiring the design of scalable hydrodynamic systems based on those in nature.
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PDF链接：
https://arxiv.org/pdf/1310.3737