Periodic breathing during ascent to extreme altitude quantified by spectral analysis of the respiratory volume signal. - Garde, Ainara; Giraldo, Beatriz F.; Jané, Raimon; Latshang, Tsogyal D.; Turk, Alexander J.; Hess, Thomas; Bosch, Martina M.; Barthelmes, Daniel; Hefti, Jaqueline Pichler; Maggiorini, Marco; Hefti, Urs; Merz, Tobias M.; et al. (2012)