Abstract
Stress can impact multiple psychological and physiological human domains. In order to better understand the effect of stress on cognitive performance, and whether this effect is related to an autonomic response to stress, the Trier Social Stress Test (TSST) was used as a testing platform along with a 2-Choice Reaction Time Task. When considering the nature and importance of Air Traffic Controllers (ATCs) work and the fact that they are subjected to high levels of stress, this study was conducted with a sample of ATCs (n = 11). Linear Heart Rate Variability (HRV) features were extracted from ATCs electrocardiogram (ECG) acquired using a medical-grade wearable ECG device (Vital Jacket((R)) (1-Lead, Biodevices S.A, Matosinhos, Portugal)). Visual Analogue Scales (VAS) were also used to measure perceived stress. TSST produced statistically significant changes in some HRV parameters (Average of normal-to-normal intervals (AVNN), Standard Deviation of all NN (SDNN), root mean square of differences between successive rhythm-to-rhythm (RR) intervals (RMSSD), pNN20, and LF/HF) and subjective measures of stress, which recovered after the stress task. Although these short-term changes in HRV showed a tendency to normalize, an impairment on cognitive performance was evident. Despite that participant's reaction times were lower, the accuracy significantly decreased, presenting more errors after performing the acute stress event. Results can also point to the importance of the development of quantified occupational health (qOHealth) devices to allow for the monitoring of stress responses.

Abstract
Optical Tweezers (OTs) have been widely applied in Biology, due to their outstanding focusing abilities, which make them able to exert forces on micro-sized particles. The magnitude of such forces (pN) is strong enough to trap their targets. However, the most conventional OT setups are based on complex configurations, being associated with focusing difficulties with biologic samples. Optical Fiber Tweezers (OFTs), which consist in optical fibers with a lens in one of its extremities are valuable alternatives to Conventional Optical Tweezers (COTs). OFTs are flexible, simpler, low-cost and easy to handle. However, its trapping performance when manipulating biological and complex structures remains poorly characterized. In this study, we experimentally characterized the optical trapping of a biological cell found within a culture of rodent glial neuronal cells, using a polymeric lens fabricated through a photo-polymerization method on the top of a fiber. Its trapping performance was compared with two synthetic microspheres (PMMA, polystyrene) and two simple cells (a yeast and a Drosophila Melanogaster cell). Moreover, the experimental results were also compared with theoretical calculations made using a numerical model based on the Finite Differences Time Domain. It was found that, although the mammalian neuronal cell had larger dimensions, the magnitude of forces exerted on it was the lowest among all particles. Our results allowed us to quantify, for the first time, the complexity degree of manipulating such "demanding" cells in comparison with known targets. Thus, they can provide valuable insights about the influence of particle parameters such as size, refractive index, homogeneity degree and nature (biologic, synthetic). Furthermore, the theoretical results matched the experimental ones which validates the proposed model.

Abstract
Background: Air Traffic Control (ATC) is a complex and demanding process, exposing Air Traffic Controllers (ATCs) to high stress. Recently, efforts have been made in ATC to maintain safety and efficiency in the face of increasing air traffic demands. Computer simulations have been a useful tool for ATC training, improving ATCs skills and consequently traffic safety. Objectives: This study aims to: a) evaluate psychophysiological indices of stress in an ATC simulation environment using a wearable biomonitoring platform. In order to obtain a measure of ATCs stress levels, results from an experimental study with the same participants, that included a stress-induced task were used as a stress ground truth; b) understand if there are differences in stress levels of ATCs with different job functions (“advisors” vs “operationals”) when performing an ATC Refresher Training, in a simulator environment. Methods: Two studies were conducted with ATCs: Study 1, that included a stress-induced task - the Trier Social Stress Test (TSST) and Study 2, that included an ATC simulation task. Linear Heart Rate Variability (HRV) features from ATCs were acquired using a medical grade wearable Electrocardiogram (ECG) device. Self-reports were used to measure perceived stress. Results: TSST was self-reported as being much more stressful than the simulation task. Physiological data supports these results. Results from study 2 showed more stress among the “advisors” group when comparing to the “operational” group. Conclusion: Results point to the importance of the development of quantified Occupational Health (qOHealth) devices to allow monitoring and differentiation of ATCs stress responses. © 2018 Donato and Denaro.

Abstract
Optical fiber tweezers have been gaining prominence in several applications in Biology and Medicine. Due to their outstanding focusing abilities, they are able to trap and manipulate microparticles, including cells, needing any physical contact and with a low degree of invasiveness to the trapped cell. Recently, we proposed a fiber tweezer configuration based on a polymeric micro-lens on the top of a single mode fiber, obtained by a self-guided photopolymerization process. This configuration is able to both trap and identify the target through the analysis of short-term portions of the back-scattered signal. In this paper, we propose a variant of this fabrication method, capable of producing more robust fiber tips, which produce stronger trapping effects on targets by as much as two to ten fold. These novel lenses maintain the capability of distinguish the different classes of trapped particles based on the back-scattered signal. This novel fabrication method consists in the introduction of a multi mode fiber section on the tip of a single mode (SM) fiber. A detailed description of how relevant fabrication parameters such as the length of the multi mode section and the photopolymerization laser power can be tuned for different purposes (e.g., microparticles trapping only, simultaneous trapping and sensing) is also provided, based on both experimental and theoretical evidences.

Abstract

Abstract
A new fabrication method of polymeric optical fiber tweezers with a multi-mode tip is presented. Preliminary results show higher robustness, improved ability for 2D trapping and differentiation of particles based on back-scattering analysis. © OSA 2018 © 2018 The Author(s)