Bladder stone collects in the bladder and minerals like calcium start to precipitate. Other individuals who develop bladder stones include those who have had spinal cord injury, paralysis, or some type of nerve damage. When nerves to the back are damaged, the bladder cannot empty, resulting in stagnant urine. Bladder stones may occur whenever the kidneys, bladder, or ureters become inflamed, which may occur when the urine becomes too concentrated or when the body becomes dehydrated. Minerals such as calcium and magnesium crystallize into the stones, which then can cause such symptoms as lower back or abdominal pain or difficulty with urination.
Ludwieg tube Ludwieg tube A Ludwieg tube is a cheap and efficient way of producing supersonic flow. Mach numbers up to 4 in air are easily obtained without any additional heating of the flow. With heating, Mach numbers of up to 11 can be reached. A Ludwieg tube is a wind tunnel that produces supersonic flow for short periods of time. A large evacuated dump tank is separated from the downstream end of a convergent-divergent nozzle by a diaphragm or fast acting valve. The upstream end of the nozzle connects to a long cylindrical tube, whose cross-sectional area is significantly larger than