American journal of medicine and medical sciences

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The urinary system works effectively across a range of length scales. This robustness is caused by the hydrodynamic contribution of the urethra. It was simply defined as a conduit between bladder and genitals.

Engineers may apply this result to design a system of pipes and reservoirs for which the drainage time does palaeogeography palaeoclimatology palaeoecology journal depend on system size. This concept of a scalable hydrodynamic system may be used in the design of portable reservoirs, such as water towers, water backpacks, and storage tanks.

Why is urination time 21 s, and why american journal of medicine and medical sciences this time constant across animal sizes. The numerical value of 21 s arises from the underlying physics involving the physical properties of urine as well as the dimensions of the urinary system. Our model shows that differences in bladder capacity are offset by differences in flow rate, resulting in a bladder emptying time that american journal of medicine and medical sciences not change with system size.

Such american journal of medicine and medical sciences has been observed in a number of other systems. Examples include the height of a jump (64) and the number of heartbeats in a lifetime (65). Many of these examples arise from some aspect of isometry, such as with our system.

Because bladder volume is 4. Because the time to urinate once is 21 s, the daily urination time is 2 min, which can be translated to 0.

Thus, urination time likely does not influence animal fitness. In our study, we found that urination time is highly sensitive to urethral cross-section. This dependency is particularly high for small animals for which urine flow is resisted by capillary and viscous forces, which scale with the perimeter of the urethra.

More accurate predictions for small american journal of medicine and medical sciences require measurements of the urethral exit perimeter and the urethral cross-section, which is known to vary with distance down the urethra (67). Current models of noncircular pipe flow are not applicable, because they only account for infinitesimal corrugations (68).

Additional mathematical techniques as well as accurate urethral measurements are needed to increase correspondence with experiments. We filmed urination of animals using both Sony HDR-XR200 and high-speed cameras (Vision Whey v210 and Miro 4).

The masses of animals american journal of medicine and medical sciences taken from annual veterinary procedures or measured using an analytical balance. Flow rate Q is measured by simultaneous high-speed videography and manual urine collection using containers of appropriate size and shape. We use the open-source software Tracker to measure the time course of the radius of urine drops produced by rats and mice.

We acknowledge photographer C. Hobbs and our hosts at Zoo Atlanta (R. Snyder), the University of Georgia (L.

Elly), the Atlanta Humane Society (A. Lopez), and the animal facilities at Georgia Tech 625 augmentin. Our funding sources were National Science Foundation Faculty Early Career Development Program (Division of Physics) Grant 1255127 for the modeling and Georgia Tech President's Undergraduate Research Awards for the experiments.

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Yang, Jonathan Pham, Jerome Choo, and David L. AbstractMany urological studies rely on models of animals, such as rats and pigs, but their relation to the human urinary system is poorly understood. Measured allometric relationships for the urinary system american journal of medicine and medical sciences animalsSteady-State Equation of Urine Flow.

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Comments:

03.03.2019 in 22:39 medddocksujec:
Круто, спасибо! ;)

04.03.2019 in 23:30 Изабелла:
аффтору зачет. СПС

08.03.2019 in 07:51 Раиса:
Напомнили….Точно, все так.

08.03.2019 in 15:02 Милен:
Я думаю, что Вы не правы. Я уверен. Предлагаю это обсудить. Пишите мне в PM.

10.03.2019 in 03:03 Анатолий:
По моему мнению Вы не правы. Пишите мне в PM, обсудим.