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Visually pulsating auroras appear as irregular patches of luminosity turning on and off in a periodic fashion with periods from 2 sec to 20 sec . Endoscopic high-frequency ultrasound ( 10 to 20 MHz ) was able to measure the vertical extension of laryngeal carcinomas bigger than 3 mm in size . The report estimates that the costs to the industrialized countries of achieving the Kyoto protocol targets , without the benefits of an international emissions trading system , would be 0.2 to 2.0 percent of projected GDP in 2010 . Newly developed ultrasound catheters with frequencies between 10 to 20 MHz were inserted in the laryngeal lumen and moved in a standardized pattern during the examination . All instruments are designed to enter the body through tiny orifices , usually from 10 to 20 mm . The fatigue threshold decreased from 25 to 20 J / m2 after aging for 7 days and to 10 J / m2 following aging for 30 days .