Electric motors can deliver a range of speeds and torques without necessarily using a gearbox (although it may be more economical to use one). Electric motors are limited in their use chiefly by the difficulty of supplying electricity.Compressed gas motors have been used on some vehicles experimentally. They are simple, efficient, safe, cheap, reliable and operate in a variety of conditions. One of the difficulties met when using gas motors is the cooling effect of expanding gas. These engines are limited by how quickly they absorb heat from their surroundings. The cooling effect can, however, double as air conditioning. Compressed gas motors also lose effectiveness with falling gas pressure.Ion thrusters are used on some satellites and spacecraft. They are only effective in a vacuum, which limits their use to spaceborne vehicles. Ion thrusters run primarily off electricity, but they also need a propellant such as caesium, or more recently xenon. Ion thrusters can achieve extremely high speeds and use little propellant; however they are power-hungry. Converting energy to work
The mechanical energy that motors and engines produce must be converted to work by wheels, propellers, nozzles, or similar means. Aside from converting mechanical energy into motion, wheels allow a vehicle to roll along a surface and, with the exception of railed vehicles, to be steered. Wheels are ancient technology, with specimens being discovered from over 5000 years ago. Wheels are used in a plethora of vehicles, including motor vehicles, armoured personnel carriers, amphibious vehicles, airplanes, trains, skateboards and wheelbarrows.
Mortality during the chronic phase is very low. Cause
Carrions disease is caused by Bartonella bacilliformis. Recent investigations show that Candidatus Bartonella ancashi may cause verruga peruana, although it may not meet all of Kochs postulates. There has been no experimental reproduction of the Peruvian wart in animals and there is little research on the diseases natural spread or impact in native animals. Diagnosis
Diagnosis during the acute phase can be made by obtaining a peripheral blood smear with Giemsa stain, Columbia blood agar cultures, immunoblot, indirect immunofluorescence, and PCR. Diagnosis during the chronic phase can be made using a Warthin-Starry stain of wart biopsy, PCR, and immunoblot. Treatment
Because Carrions disease is often comorbid with Salmonella infections, chloramphenicol has historically been the treatment of choice.Fluoroquinolones (such as ciprofloxacin) or chloramphenicol in adults and chloramphenicol plus beta-lactams in children are the antibiotic regimens of choice during the acute phase of Carrions disease. Chloramphenicol-resistant B. bacilliformis has been observed.During the eruptive phase, in which chloramphenicol is not useful, azithromycin, erythromycin, and ciprofloxacin have been used successfully for treatment. Rifampin or macrolides are also used to treat both adults and children.Because of the high rates of comorbid infections and conditions, multiple treatments are often required. These have included the use of corticosteroids for respiratory distress, red blood cell transfusions for anemia, pericardiectomies for pericardial tamponades, and other standard treatments. == References ==