O2 HEAT EQUIVALENCE...
CO2 HEAT EQUIVALENCE... These options let
you set the caloric equivalent of one ml of oxygen or CO2;
the defaults are 20.1 joules/ml O2 and 25.0
joules/ml CO2. You can click buttons to
select appropriate values for carbohydrate, lipid, or protein substrates.
It is possible to directly enter your own value into the edit field, however.
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This window appears automatically during gas exchange calculations if
you select output units of energy instead of gas volume.
EFFECTIVE VOLUME... (Active channel only)
Uses a recorded gas washout curve to compute the 'effective volume' of an
open-circuit respirometry system. Effective volume is an expression
of the ratio of system volume to flow rate (it corresponds only approximately
to the real volume of chamber and plumbing). This routine bases
its calculations on washout rates of any gas, as long as the washout deflection
is measured as a change in % concentration and the equilibrium concentration
is offset to a 'baseline' of zero. This is done either during measurement
or with the baseline correction and transformations routines in LabAnalyst.
To generate a washout curve, set up the respirometry system as it is
normally used (but without an animal) at the flow rate used for measurements.
Make a recording of gas concentration, starting at equilibrium levels.
After establishing a baseline, deflect concentration by rapidly exhaling
into the incurrent flow upstream from the chamber (or quickly inject a bolus
of some gas with different concentration than reference gas). Continue
recording as gas concentration rapidly peaks, slowly declines, and eventually
returns to equilibrium concentration. Save the data. In LabAnalyst, correct the baseline to zero,
even for oxygen files (it will probably help to smooth
the data also). Mark a block in the washout curve as it returns to
equilibrium. Usually it is best to select from the middle of the washout
curve. Then select the effective volume option. LabAnalyst will request the flow rate and compute effective volume.
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