Jean-François Gagnon

Using near infrared spectroscopy and heart rate variability to detect mental overload

Mental workload is a key factor influencing the occurrence of human error, especially during piloting and remotely operated vehicle (ROV) operations, where safety depends on the ability of pilots to act appropriately. In particular, excessively high or low mental workload can lead operators to neglect critical information. The objective of the present study is to investigate the potential of functional near infrared spectroscopy (fNIRS) - a non-invasive method of measuring prefrontal cortex activity - in combination with measurements of heart rate variability (HRV), to predict mental workload during a simulated piloting task, with particular regard to task engagement and disengagement. Twelve volunteers performed a computer-based piloting task in which they were asked to follow a dynamic target with their aircraft, a task designed to replicate key cognitive demands associated with real life ROV operating tasks. In order to cover a wide range of mental workload levels, task difficulty was manipulated in terms of processing load and difficulty of control - two critical sources of workload associated with piloting and remotely operating a vehicle. Results show that both fNIRS and HRV are sensitive to different levels of mental workload; notably, lower prefrontal activation as well as a lower LF/HF ratio at the highest level of difficulty, suggest that these measures are suitable for mental overload detection. Moreover, these latter measurements point toward the existence of a quadratic model of mental workload.

Quantitative DNA methylation analysis of laser capture microdissected formalin-fixed and paraffin-embedded tissues

We developed an assay to quantify DNA methylation in breast cancer cells isolated by laser capture microdissection (LCM). The assay uses methylation sensitive restriction enzyme (MSRE) digestion and quantitative polymerase chain reaction (qPCR). To assess the validity and precision of the assay, we prepared standard samples with expected methylation percentage (MP) for two gene promoters (PLAU (plasminogen inhibitor, urokinase) and TIMP3 (TIMP metallopeptidase inhibitor 3)) that we compared with measured MPs. We found good linearity of MSRE digestion and qPCR procedures for both promoters (beta=0.90-1.19+/-0.05-0.10 and r=0.95-0.98; all P<0.0001). Moreover, results remained similar after addition of a purification step between MSRE digestion and qPCR procedures. The validity of this technique was also confirmed by successfully replicating previously published MPs of four cell lines for PLAU and TIMP3 promoters. We assessed the consistency of our approach by comparing MPs of PLAU and TIMP3 promoters from nine breast cancer patients and two cell lines using LCM frozen tissues and their corresponding formalin-fixed paraffin-embedded tissues. We found good consistency (intraclass correlation coefficient=0.93) of MPs between frozen tissues and formalin-fixed paraffin-embedded tissues. Our data demonstrate that this assay based on digestion with MSRE and qPCR procedures is a good technique to quantify MP on limited amounts of DNA and may find clinical applications.

Immunohistochemistry of breast tumor markers on archived bouin-fixed paraffin-embedded tissues.

Neutral-buffered formalin is the most commonly used tissue fixative in pathology laboratory. Among other fixatives, Bouins solution has been used in several laboratories and is still in use for particular tissues. In this project, we determine if we can study breast clinical markers on archived Bouin-fixed tissue samples with immunohistochemistry (IHC) protocols optimized for tissue fixed in neutral-buffered formalin. To evaluate the concordance of IHC results between formalin-fixed and Bouin-fixed tissues, we calculated the concordance percentage and the &kgr; statistic of 12 clinical IHC markers quantified by an automated system on breast cancer tissues fixed in neutral-buffered formalin and their corresponding tissues fixed in Bouins solution. When positivity threshold of immunostaining was setup at ≥10% for both fixation conditions, we observed a concordance percentage of 83.9% (&kgr;=0.65). However, when positivity threshold of immunostaining was lowered to 3% to 4% for Bouin-fixed tissues, concordance percentage was then of 96.8% (&kgr;=0.92). Our data demonstrate that we can study IHC markers on archived Bouin-fixed tissue from patients with long clinical follow-up using IHC protocols optimized for formalin-fixed tissues after an adjustment of the positivity threshold of immunostaining quantified by an automated system.

Predicting Stress among Pedestrian Traffic Workers Using Physiological and Situational Measures

Traffic workers are vulnerable to accidents and must make critical decisions to avoid conflicts between road users. This can lead to high stress levels, which may hinder their capacity to mitigate the occurrence of hazards. Measuring stress on the field could represent an efficient solution to help pinpoint risky situations and identify factors that increase risk. The goal of this study was to verify whether stress among traffic workers could be predicted using physiological measures and characteristics of the work situation. Nineteen police officers in Quebec City and Montreal, Canada, performed traffic duties while their physiological activity was assessed by a wearable physiological harness. Every 15 minutes, change in subjective stress was also measured. Results showed that decision-tree models outperformed multifactorial logistic regressions for predicting subjective stress based on both situational factors and physiological measures. This demonstrated the potential of using such measures to monitor stress among traffic workers.

Crew Performance and Situation Awareness in Three UAS GCS Layouts

The aim of Canada’s Joint Unmanned Surveillance and Target Acquisition System program is to acquire an Unmanned Aircraft System (UAS) for Royal Canadian Air Force’s domestic and international operations. This UAS will be capable of complementing existing reconnaissance, surveillance, target acquisition, and engagement capabilities. Defence Research and Development Canada has developed a UAS ground control station simulator to investigate crew layouts, airworthiness certification, UAS crew training technologies and strategies, as well as novel human-machine interfaces. This paper investigates crew performance and situation awareness in three layouts of the ground control station: distributed, classroom, and boardroom. Preliminary results indicate that the boardroom layout outperforms the other layouts in terms of crew communication, teamwork and situation awareness.

Multi-criteria assessment of a whole-of-government planning methodology using MYRIAD

The present work describes the application of a multi-criteria assessment tool called MYRIAD to the evaluation of a methodology that was developed to improve team understanding of a complex situation. The methodology aims to support a multi-disciplinary team working collaboratively on the development of a mission plan during an expeditionary stability operation. We conducted a case study assessing collaborative understanding and team performance while subject matter experts employed the methodology as a complement to the standard planning process. Results were analyzed using MYRIAD, a preference modeling system that allows combining disparate measures into a coherent assessment capturing several key logical relationships between metrics - ones that may not be modeled using the traditional weighted sum approach. MYRIAD was also used to perform a sensitivity analysis in order to derive from the preference model which aspects of the planning methodology would lead to the greatest overall improvement. Results helped identifying priority areas for future development.