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Tricia Adjei, Jingwen Xue, Danilo P Mandic
Sex differences in the study of the human physiological response to mental stress are often erroneously ignored. To this end, we set out to show that our understanding of the stress response is fundamentally altered once sex differences are taken into account. This is achieved by comparing the heart rate variability (HRV) signals acquired during mental maths tests from ten females and ten males of similar maths ability; all females were in the follicular phase of their menstrual cycle. For rigor, the HRV signals from this pilot study were analyzed using temporal, spectral and nonlinear signal processing techniques, which all revealed significant statistical differences between the sexes, with the stress-induced increases in the heart rates from the males being significantly larger than those from the females ( p -value = 4...
2018: Frontiers in Physiology
Luis Montesinos, Rossana Castaldo, Leandro Pecchia
BACKGROUND: Approximate entropy (ApEn) and sample entropy (SampEn) have been previously used to quantify the regularity in centre of pressure (COP) time-series in different experimental groups and/or conditions. ApEn and SampEn are very sensitive to their input parameters: m (subseries length), r (tolerance) and N (data length). Yet, the effects of changing those parameters have been scarcely investigated in the analysis of COP time-series. This study aimed to investigate the effects of changing parameters m, r and N on ApEn and SampEn values in COP time-series, as well as the ability of these entropy measures to discriminate between groups...
December 12, 2018: Journal of Neuroengineering and Rehabilitation
Gary Tse, Yimei Du, Guoliang Hao, Ka Hou Christien Li, Fiona Yin Wah Chan, Tong Liu, Guangping Li, George Bazoukis, Konstantinos P Letsas, William K K Wu, Shuk Han Cheng, Wing Tak Wong
Background: Beat-to-beat variability in action potential duration (APD) is an intrinsic property of cardiac tissue and is altered in pro-arrhythmic states. However, it has never been examined in mice. Methods: Left atrial or ventricular monophasic action potentials (MAPs) were recorded from Langendorff-perfused mouse hearts during regular 8 Hz pacing. Time-domain, frequency-domain and non-linear analyses were used to quantify APD variability. Results: Mean atrial APD (90% repolarization) was 23.5 ± 6.3 ms and standard deviation (SD) was 0...
2018: Frontiers in Physiology
Alex Rizzato, Gerardo Bosco, Michael Benazzato, Antonio Paoli, Giulia Zorzetto, Attilio Carraro, Giuseppe Marcolin
Postural balance control can be altered by land treadmill (LTM) running. This impairment seems to be related to a disturbance of vestibular and visual information. However, no studies are available on aquatic treadmill (ATM) running. The aim of the present study was to investigate the effect of running at moderate intensity over ATM and LTM on the postural balance control both with opened (OE) and closed (CE) eyes. Center of pressure (CoP) trajectory of 20 healthy subjects was collected on a dynamometric platform before and after a 20-min-long running on ATM and LTM at the same rate of perceived exertion (Borg's scale: 3/10)...
2018: Frontiers in Physiology
Tatiana Ismagulova, Anastasia Shebanova, Olga Gorelova, Olga Baulina, Alexei Solovchenko
We established a new simple approach to study phosphorus (P) and nitrogen (N) reserves at subcellular level potentially applicable to various types of cells capable of accumulating P- and/or N-rich inclusions. Here, we report on using this approach for locating and assessing the abundance of the P and N reserves in microalgal and cyanobacterial cells. The approach includes separation of the signal from P- or N-rich structures from noise on the energy-filtered transmission electron microscopy (EFTEM) P- or N-maps...
2018: PloS One
Qi Qi, Yanlong Li, Jitian Wang, Han Zheng, Yue Huang, Xinghao Ding, Gustavo Rohde
The automatic classification of breast cancer histopathological images has great significance in computer-aided diagnosis. Recently, deep learning via neural networks has enabled pattern detection and prediction using large, labeled datasets; whereas, collecting and annotating sufficient histological data using professional pathologists is time-consuming, tedious, and extremely expensive. In the proposed work, a deep active learning framework is designed and implemented for classification of breast cancer histopathological images, with the goal of maximizing the learning accuracy from very limited labeling...
December 5, 2018: IEEE Journal of Biomedical and Health Informatics
Daniel E Dawson, Trevor S Farthing, Michael W Sanderson, Cristina Lanzas
Dynamic contact data can be used to inform disease transmission models, providing insight into the dynamics of infectious diseases. Such data often requires extensive processing for use in models or analysis. Therefore, processing decisions can potentially influence the topology of the contact network and the simulated disease transmission dynamics on the network. In this study, we examine how four processing decisions, including temporal sampling window (TSW), spatial threshold of contact (SpTh), minimum contact duration (MCD), and temporal aggregation (daily or hourly) influence the information content of contact data (indicated by changes in entropy) as well as disease transmission model dynamics...
August 29, 2018: Epidemics
Victor Pacheco, Greta Lindwall, Dennis Karlsson, Johan Cedervall, Stefan Fritze, Gustav Ek, Pedro Berastegui, Martin Sahlberg, Ulf Jansson
The multicomponent alloy HfNbTiVZr has been described as a single-phase high-entropy alloy (HEA) in the literature, although some authors have reported that additional phases can form during annealing. The thermal stability of this alloy has therefore been investigated with a combination of experimental annealing studies and thermodynamic calculations using the CALPHAD approach. The thermodynamic calculations show that a single-phase HEA is stable above about 830 °C. At lower temperatures, the most stable state is a phase mixture of bcc, hcp, and a cubic C15 Laves phase...
December 11, 2018: Inorganic Chemistry
Kai U Cormann, Meike Baumgart, Michael Bott
The development of biosensors for in vitro quantification of small molecules such as metabolites or man-made chemicals is still a major challenge. Here we show that engineered variants of the sensory PAS domain of the histidine kinase CitA of the thermophilic bacterium Geobacillus thermoleovorans represent promising alternatives to established biorecognition elements. By combining binding site grafting and rational design we constructed protein variants binding l-malate, ethylmalonate, or the aromatic compound phthalate instead of the native ligand citrate...
December 10, 2018: ACS Synthetic Biology
Intan Low, Po-Chih Kuo, Cheng-Lin Tsai, Yu-Hsiang Liu, Ming-Wei Lin, Hsiang-Tai Chao, Yong-Sheng Chen, Jen-Chuen Hsieh, Li-Fen Chen
The irregularity and uncertainty of neurophysiologic signals across different time scales can be regarded as neural complexity, which is related to the adaptability of the nervous system and the information processing between neurons. We recently reported general loss of brain complexity, as measured by multiscale sample entropy (MSE), at pain-related regions in females with primary dysmenorrhea (PDM). However, it is unclear whether this loss of brain complexity is associated with inter-subject genetic variations...
2018: Frontiers in Neuroscience
Qiao Li, Qichen Li, Chengyu Liu, Supreeth Prajwal Shashikumar, Shamim Nemati, Gari D Clifford
This study classifies sleep stages from a single lead electrocardiogram (ECG) using beat detection, cardiorespiratory coupling in the time-frequency domain and a deep convolutional neural network (CNN). 
 Approach: An ECG-derived respiration (EDR) signal and synchronous beat-to-beat heart rate variability (HRV) time series were derived from the ECG using previously described robust algorithms. A measure of cardiorespiratory coupling (CRC) was extracted by calculating the coherence and cross-spectrogram of the EDR and HRV signal in five-minute windows...
November 23, 2018: Physiological Measurement
Dmitry V Matyushov, Marshall D Newton
We present a thermodynamic analysis of the activation barrier for reactions which can be monitored through the difference in the energies of reactants and products defined as the reaction coordinate (electron and atom transfer, enzyme catalysis, etc). The free-energy surfaces along the reaction coordinate are separated into the enthalpy and entropy surfaces. For the Gaussian statistics of the reaction coordinate, the free-energy surfaces are parabolas, and the entropy surface is an inverted parabola. Its maximum coincides with the transition state for reactions with zero value of the reaction free energy...
December 4, 2018: Journal of Physical Chemistry. B
Jiannan Kang, Huimin Chen, Xin Li, Xiaoli Li
Autism spectrum disorder (ASD) is a complex and heterogeneous neurodevelopmental disorder, which is characterized by impairments of social interaction and communication, and by stereotyped and repetitive behaviors. Extensive evidences demonstrated that the core neurobiological mechanism of autism spectrum disorder is aberrant neural connectivity, so the entropy of EEG can be applied to quantify this aberrant neural connectivity. In this study, we investigated four entropy methods to analyse the resting-state EEG of the autistic children and the typical development (TD) children...
November 28, 2018: Journal of Clinical Neuroscience: Official Journal of the Neurosurgical Society of Australasia
Andrew Hsu, Fabien Ferrage, Arthur G Palmer
Spin relaxation in solution-state NMR spectroscopy is a powerful approach to explore the conformational dynamics of biological macromolecules. Probability distribution functions for overall or internal correlation times have been used previously to model spectral density functions central to spin-relaxation theory. Applications to biological macromolecules rely on transverse relaxation rate constants, and when studying nanosecond timescale motions, sampling at ultralow frequencies is often necessary. Consequently, appropriate distribution functions necessitate spectral density functions that are accurate and convergent as frequencies approach zero...
November 6, 2018: Biophysical Journal
Anat V Lubetzky, Bryan D Hujsak, Jennifer L Kelly, Gene Fu, Ken Perlin
BACKGROUND: Deficits in sensory integration and fear of falling in complex environments contribute to decreased participation of adults with vestibular disorders. With recent advances in virtual reality technology, head-mounted displays are affordable and allow manipulation of the environment to test postural responses to visual changes. OBJECTIVES: To develop an assessment of static and dynamic balance with the Oculus Rift and (1) to assess test-retest reliability of each scene in adults with and without vestibular hypofunction; (2) to describe changes in directional path and sample entropy in response to changes in visuals and surface and compare between groups; and (3) to evaluate the relation between balance performance and self-reported disability and balance confidence...
November 2018: PM & R: the Journal of Injury, Function, and Rehabilitation
Michael N Hallquist, Alexandre Y Dombrovski
In natural environments with many options of uncertain value, one faces a difficult tradeoff between exploiting familiar, valuable options or searching for better alternatives. Reinforcement learning models of this exploration/exploitation dilemma typically modulate the rate of exploratory choices or preferentially sample uncertain options. The extent to which such models capture human behavior remains unclear, in part because they do not consider the constraints on remembering what is learned. Using reinforcement-based timing as a motivating example, we show that selectively maintaining high-value actions compresses the amount of information to be tracked in learning, as quantified by Shannon's entropy...
November 28, 2018: Cognition
William Johnston, Martin O'Reilly, Ciara Duignan, Mairead Liston, Rod McLoughlin, Garrett F Coughlan, Brian Caulfield
BACKGROUND: Concussion is one of the most common sports-related injuries, with little understood about the modifiable and nonmodifiable risk factors. Researchers have yet to evaluate the association between modifiable sensorimotor function variables and concussive injury. PURPOSE: To investigate the association between dynamic balance performance, a discrete measure of sensorimotor function, and concussive injuries. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3...
December 3, 2018: American Journal of Sports Medicine
Jamie Pethick, Katherine Whiteaway, Samantha L Winter, Mark Burnley
NEW FINDINGS: What is the central question of this study? Does eccentric exercise leading to prolonged knee-extensor torque depression also result in a prolonged loss of knee-extensor torque complexity? What is the main finding and its importance? The recovery of the loss of torque complexity after eccentric exercise took 24 h, whereas after acute muscle fatigue it took 10 min. The depression of torque complexity after eccentric exercise was prolonged. ABSTRACT: Neuromuscular fatigue reduces the temporal structure, or complexity, of muscle torque output...
November 28, 2018: Experimental Physiology
Masafumi Terada, Nathan Johnson, Kyle Kosik, Phillip Gribble
PURPOSE: This study aimed to quantify differences in white matter microstructure and static postural control in individuals with and without a previous history of a lateral ankle sprain. METHODS: Ten participants with a history of a lateral ankle sprain and 10 controls performed 3, 20-second trials of single-leg static balance on a force platform under an eyes-open condition. Resultant sample entropy (SampEn) was used to assess static postural control performance...
November 21, 2018: Medicine and Science in Sports and Exercise
Pranab Sarker, Tyler Harrington, Cormac Toher, Corey Oses, Mojtaba Samiee, Jon-Paul Maria, Donald W Brenner, Kenneth S Vecchio, Stefano Curtarolo
High-entropy materials have attracted considerable interest due to the combination of useful properties and promising applications. Predicting their formation remains the major hindrance to the discovery of new systems. Here we propose a descriptor-entropy forming ability-for addressing synthesizability from first principles. The formalism, based on the energy distribution spectrum of randomized calculations, captures the accessibility of equally-sampled states near the ground state and quantifies configurational disorder capable of stabilizing high-entropy homogeneous phases...
November 26, 2018: Nature Communications
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