Table 1.
Participant description.
Fig 1.
Schematic diagram of environmental chamber.
Testing environment set up, containing a built-in heater and AC unit. An environmental sensor was attached to the back wall to monitor the environmental conditions while testing to maintain proper conditions. A go/ no go olfactometer testing apparatus was placed in the front of the room to preform training and testing.
Table 2.
Description of odorants.
Fig 2.
Diagram of mass air flow dilution olfactometer.
The path of air flow is shown from left to right. Clean air travels through a warm water bath heated to replicate the same temperature of the odorant water bath. The clean air then travels to the manifold and is dispersed to the MFC A, MFC B and MFC E. Air from MFC A is pushed into the vial containing an odorant located in a separate water bath to collect the headspace from the vial and then pushed out of the vial to a three-way junction connected to MFC B. The air from the vial is mixed with clean air from the manifold the travels to the remaining mass air flow controllers. The odorant is systematically diluted by the mass air flow controllers and then pushed down the odor line to be delivered to the port.
Table 3.
Environmental conditions of threshold assessment.
Fig 3.
The dog Jack following the 3-down 1-up adaptive threshold procedure for C-4 in standard conditions.
After three correct responses, the concentration was decreased by a half-log. Once Jack responded incorrectly when presented with 0.01 dilution of C4, the concentration was increased by a half-log. Jack correctly alerted 0.01 dilution of C4 but was not able to detect lower concentrations. Eight reversals were reached during testing and threshold was calculated as the geometric mean of the last six reversals.
Fig 4.
Average threshold of each odor.
Displaying average dilution of vapor saturation threshold across all dogs for both testing sessions in standard conditions of each odor. SP, C4, AN, and TNT. Error bars show 95% bootstrap estimated confidence intervals.
Table 4.
Detection limit (log of vapor saturation) for each odor in each condition and 95% confidence intervals.
Fig 5.
Threshold (log proportion of vapor saturation) for each environmental condition and odor.
Error bars show bootstrap estimated 95% confidence intervals.
Fig 6.
Individual threshold difference for each environment condition compared to standard condition for dogs detecting SP.
Average threshold between both testing sessions for each condition.
Table 5.
Threshold difference for each environment condition compared to standard condition.
Positive t-ratio indicates poorer sensitivity compared to standard.
Fig 7.
Implanted skin temperature during testing.
Error bars show the 95% confidence interval.
Fig 8.
Threshold relation to mean subcutaneous temperature.
Line shows the best fit regression.
Fig 9.
Respiratory effort ratings during the threshold assessments.
Error bars show the boot strap estimated 95% confidence intervals.
Fig 10.
Relationship between mean RE and log threshold.
Fig 11.
Latency to sample odor port by environmental condition.
Error bars show the 95% bootstrap estimated confidence intervals.
Fig 12.
Relationship between mean latency to initiate a trial in a session with overall threshold.