Musical instruments that start with the letter I include the igil, ipu, Irish uillean, Irish bouzouki, ichigenkin, inci, iya, itotele and istarski mih. The instruments originate from countries ranging from Cuba and Ireland to Croatia, Japan and the Philippines.
Bessel's functions are often used in acoustics for describing circular membranes behaviour (exploited by most of the musical instruments). They are the solutions of the wave equations using polar coordinates. Set the properties of the membrane Bessel's functions describe the vibrational modes of the membrane.
Tubing used to deliver oxygen at levels from 1 to 6 L/min. The nasal prongs of the cannula extend approx. 1 cm into each naris and are connected to a common tube, which is then connected to the oxygen source. It is used to treat conditions in which a slightly enriched oxygen content is needed, such as emphysema.