Non-Uniform Sample Assignment in Training Set Improving Recognition of Hand Gestures Dominated with Similar Muscle Activities

So far, little is known how the sample assignment of surface electromyogram (sEMG) features in training set influences the recognition efficiency of hand gesture, and the aim of this study is to explore the impact of different sample arrangements in training set on the classification of hand gestures dominated with similar muscle activation patterns. Seven right-handed healthy subjects (24.2 ± 1.2 years) were recruited to perform similar grasping tasks (fist, spherical, and cylindrical grasping) and similar pinch tasks (finger, key, and tape pinch). Each task was sustained for 4 s and followed by a 5-s rest interval to avoid fatigue, and the procedure was repeated 60 times for every task. sEMG were recorded from six forearm hand muscles during grasping or pinch tasks, and 4-s sEMG from each channel was segmented for empirical mode decomposition analysis trial by trial. The muscle activity was quantified with zero crossing (ZC) and Wilson amplitude (WAMP) of the first four resulting intrinsic mode function. Thereafter, a sEMG feature vector was constructed with the ZC and WAMP of each channel sEMG, and a classifier combined with support vector machine and genetic algorithm was used for hand gesture recognition. The sample number for each hand gesture was designed to be rearranged according to different sample proportion in training set, and corresponding recognition rate was calculated to evaluate the effect of sample assignment change on gesture classification. Either for similar grasping or pinch tasks, the sample assignment change in training set affected the overall recognition rate of candidate hand gesture. Compare to conventional results with uniformly assigned training samples, the recognition rate of similar pinch gestures was significantly improved when the sample of finger-, key-, and tape-pinch gesture were assigned as 60, 20, and 20%, respectively. Similarly, the recognition rate of similar grasping gestures also rose when the sample proportion of fist, spherical, and cylindrical grasping was 40, 30, and 30%, respectively. Our results suggested that the recognition rate of hand gestures can be regulated by change sample arrangement in training set, which can be potentially used to improve fine-gesture recognition for myoelectric robotic hand exoskeleton control

Effect of exposure to phthalates on association of polycyclic aromatic hydrocarbons with 8-hydroxy-2 '-deoxyguanosine

Background: Although polycyclic aromatic hydrocarbons (PAHs) and phthalates separately related to oxidative DNA damage have been reported, the joint effect of them on oxidative DNA damage need to be evaluated. Methods: In this pilot study, 106 participants were recruited from the community-dwelling residents (n = 1240) of Wuhan city, China. Each individual provided three continuous days of spot urine samples for measuring the urinary monohydroxylated PAHs (OH-PAHs), phthalates metabolites and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in the two seasons. Linear mixed effect model and Bayesian Kernel Machine Regression (BKMR) were used to analyze joint effect of urinary PAHs and phthalates metabolites on urinary 8-OHdG levels. We measured cellular and mitochondrial reactive oxygen species (ROS), malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) levels as well as IL-6 and IL-8 secretions by the corresponding commercial kits in HepG2 cells treated with di (2-ethylhexyl) phthalate (DEHP, 62.5, 125.00, 250.00, 500.00 or 1000.00 mu M) alone, benzo[a] pyrene (BaP, 50.00 mu M) alone or both DEHP and BaP. Results: Linear mixed effect model showed that each of urinary PAHs metabolite was positively associated with urinary 8-OHdG levels; urinary level of mono (2-ethylhexyl) phthalate ormonoisononyl phthalate was positively associated with urinary 8-OHdG levels; BKMR model indicated that a positive association of eight OH-PAHs with urinary 8-OHdG levels, nine urinary phthalates metabolites enhanced the association. We found that DEHP at the indicated concentration plus 50.00 mu M BaP increased cellular and mitochondrial ROS levels, IL-6 and IL-8 secretions at 24 and 48 h as well as MDA levels and GSH-Px activities at 48 h, compared to the solvent control. Conclusions: Exposure to certain dose phthalates may attenuate the positive association of PAHs exposure with oxidative DNA damage in the body. DEHP at the certain concentrations enhanced BaP-induced mitochondrial ROS, pro-inflammatory response and the activation of the antioxidant defense system in HepG2 cells. (c) 2019 Elsevier B.V. All rights reserved

The enhanced x-ray timing and polarimetry mission – eXTP: an update on its scientific cases, mission profile and development status

The enhanced x-ray timing and polarimetry mission (eXTP) is a flagship observatory for x-ray timing, spectroscopy and polarimetry developed by an international consortium. Thanks to its very large collecting area, good spectral resolution and unprecedented polarimetry capabilities, eXTP will explore the properties of matter and the propagation of light in the most extreme conditions found in the universe. eXTP will, in addition, be a powerful x-ray observatory. The mission will continuously monitor the x-ray sky, and will enable multi-wavelength and multi-messenger studies. The mission is currently in phase B, which will be completed in the middle of 2022