DGC, discontinuous gas exchange
D, incident beam power density
d, sample-detector distance
E, x-ray energy
Iinc, incident beam intensity
L, source-sample distance
λ, x-ray wavelength
ρ, sample density
RQ, respiratory quotient
RS, respiratory signal
R(x,y), effective detector resolution
σs, source size
TTRS, time to respiratory signal
x-y, image plane
z, beam direction
The authors declare that they have no competing interests.
The scope of this paper was conceived by all authors. JS and JW
collected most of the data. JS and WKL performed the analyses. JS and
WKL drafted the manuscript, and JH and MW contributed to the writing.
All authors read and approved the final manuscript.
We thank Kamel Fezzaa and Aaron Rice with help in collecting data,
John Lighton, Barbara Joos, and Robbin Turner of Sable Systems
International (SSI) for assistance with respirometry equipment, Kendra
Greenlee for help with the thermocouple thermometry, and Jim Liebherr
for help with identification of beetle internal anatomy. Use of the
Advanced Photon Source was supported by the U. S. Department of Energy,
Office of Science, Office of Basic Energy Sciences, under Contract No.
W-31-109-ENG-38. Harrison's work at ANL was supported by NSF
IBN-9985857 and IBN 0419704.