While the pulse detonation engine is much more efficient than the pulse jet and even turbine engines, it still suffers from extreme noise and vibration levels. Ramjets also have few moving parts, but they only work at high speed, so that their use is restricted to tip jet helicopters and high speed aircraft such as the Lockheed SR-71 Blackbird.Rocket engines are primarily used on rockets, rocket sleds and experimental aircraft. Rocket engines are extremely powerful. The heaviest vehicle ever to leave the ground, the Saturn V rocket, was powered by five F-1 rocket engines generating a combined 180 million horsepower (134.2 gigawatt). Rocket engines also have no need to "push off" anything, a fact that the New York Times denied in error. Rocket engines can be particularly simple, sometimes consisting of nothing more than a catalyst, as in the case of a hydrogen peroxide rocket. This makes them an attractive option for vehicles such as jet packs. Despite their simplicity, rocket engines are often dangerous and susceptible to explosions. The fuel they run off may be flammable, poisonous, corrosive or cryogenic. They also suffer from poor efficiency. For these reasons, rocket engines are only used when absolutely necessary.Electric motors are used in electric vehicles such as electric bicycles, electric scooters, small boats, subways, trains, trolleybuses, trams and experimental aircraft. Electric motors can be very efficient: over 90% efficiency is common. Electric motors can also be built to be powerful, reliable, low-maintenance and of any size.
It can cause frequent blockage of the ureter leading to serious kidney damage. In other cases, a small, upper portion of the kidney is congenitally non-functional. Though often benign, this problem can necessitate the removal of non-functioning parts. Causes
Definitive causes of ureterocele have not been found. While the abnormal growth occurs within the uterus, it has not been substantiated that genetics are to blame. Congenital abnormalities of the mesonephric duct in males can lead to the formation of a ureterocele, which often coincide with ipsilateral agenesis of the kidney (atrophic kidney) and seminal vesicle cysts, this is known as Zinner Syndrome. Diagnosis
IVU-shows Adder head appearance or Cobra head appearance. Cystoscopy-shows translucent cyst which is thin walled surrounding ureteric orifice

Treatment
Single-system ureterocele: initial management is usually endoscopic incision of the ureterocele, which can be followed by surgical ureteric re-implantation to preserve renal function and prevent reflux. Duplex-system ureterocele: treatment options vary with the individual and include: endoscopic incision of the corresponding ureteric orifice in case of ureteric meatal stricture; upper pole nephrectomy for a poorly functioning unit with ureterectomy or, where there is useful renal function, ureteropyelostomy. References
Further reading


== External links ==