Nowadays employment world is increasingly shifting towards service-related labour, changing focus from physiological to psychological loads for workers. Thus, a deeper psychological stress understanding arises, not only for jobs within extreme conditions (as astronauts or pilots) but also for regular jobs with high emphasis on mental stressors. With the intend of developing a method and technology able to detect psychological stress we perform this pilot laboratory study in 14 male volunteers

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... der stress and relax situations. As a stressor and the relaxer were used a standardized cognitive Paced Auditory Serial Addition Test (PASAT) and a relaxing video, respectively. Galvanic Skin Response (GSR) and Heart Rate (HR) were continuously measured as golden standard techniques to indicate physiological stress levels. Before each stimulus intervention a Braquial Blood Pressure were measured by standard Omron M6 apparatus. A continuous monitoring of Central Aortic Pressure (CAP) were assessed by non-invasive small WiFi sensors and equipment, developed by NMT, S.A., which allowed on-line detection and long-term effect of stress evaluation.HR and GSR measurements showed high variations under stressor application, proving physiological stress among volunteers and validating PASAT suitability. From analysis of obtained CAP data were found the good correlation with HR and GSR measurements in both, stress and relax sections. In addition of being a highly innovative study on mental stress detection, it is obvious the necessity of increase study population in future similar studies in lab and/or in the field condition. Objective and motivation: Endothelial dysfunction is associated with cardiovascular diseases. Flow mediated dilation (FMD), assesses the endothelial function by measuring the brachial artery vasodilation following deflation of a sphygmomanometer cuff around the forearm. Vasodilation is assumed to be due to an increase in wall shear stress (WSS) only. However, there is evidence that the vasodilation may be affected by other confounding factors1. We aim to investigate the effects of confounding factors on the results of FMD. Methods: A dynamic simulation of FMD was carried out using a one-dimensional haemodynamic solver of blood flow in the arm arterial vasculature (Fig. 1a) 2. Haemodynamics during cuff deflation was simulated by prescribing a decrease in peripheral resistance (Fig. 1b) in a novel mathematical model which dynamically couples increasing WSS (Fig. 1c) to decreasing arterial wall Young's modulus (Fig. 1d) , taking into account endothelial function. Results: Our results show that the initial increase in flow velocity (Fig. 1e) is caused by the prescribed decrease in peripheral resistance and leads to an initial pressure drop affecting the FMD value. WSS induces a drop in Young's modulus leading to vasodilation (Fig. 1f ). In addition, for the same prescribed endothelial function (relating WSS to Young's modulus variation) and decreased peripheral resistance, FMD increases with decreasing arterial stiffness (3.17% vs 5.31% vs 8.56% (Fig. 1f) ). ConclusionOur numerical model successfully described FMD haemodynamics and highlighted one of the important confounding factors of FMD values: arterial stiffness. We are currently investigating other factors and ways of correcting those factors.