18 research outputs found

    Electroencephalographic monitoring of complex mental tasks

    Get PDF
    Outlined here is the development of neurophysiological procedures to monitor operators during the performance of cognitive tasks. Our approach included the use of electroencepalographic (EEG) and rheoencephalographic (REG) techniques to determine changes in cortical function associated with cognition in the operator's state. A two channel tetrapolar REG, a single channel forearm impedance plethysmograph, a Lead I electrocardiogram (ECG) and a 21 channel EEG were used to measure subject responses to various visual-motor cognitive tasks. Testing, analytical, and display procedures for EEG and REG monitoring were developed that extend the state of the art and provide a valuable tool for the study of cerebral circulatory and neural activity during cognition

    Poincaré plot analysis of cerebral blood flow signals : feature extraction and classification methods for apnea detection

    Get PDF
    Objective: Rheoencephalography is a simple and inexpensive technique for cerebral blood flow assessment, however, it is not used in clinical practice since its correlation to clinical conditions has not yet been extensively proved. The present study investigates the ability of Poincaré Plot descriptors from rheoencephalography signals to detect apneas in volunteers. Methods:A group of 16 subjects participated in the study. Rheoencephalography data from baseline and apnea periods were recorded and Poincaré Plot descriptors were extracted from the reconstructed attractors with different time lags (t). Among the set of extracted features, those presenting significant differences between baseline and apnea recordings were used as inputs to four different classifiers to optimize the apnea detection. Results:Three features showed significant differences between apnea and baseline signals: the Poincaré Plot ratio (SDratio), its correlation (R) and the Complex Correlation Measure (CCM). Those differences were optimized for time lags smaller than those recommended in previous works for other biomedical signals, all of them being lower than the threshold established by the position of the inflection point in the CCM curves. The classifier showing the best performance was the classification tree, with 81% accuracy and an area under the curve of the receiver operating characteristic of 0.927. This performance was obtained using a single input parameter, either SDratio or R. Conclusions Poincaré Plot features extracted from the attractors of rheoencephalographic signals were able to track cerebral blood flow changes provoked by breath holding. Even though further validation with independent datasets is needed, those results suggest that nonlinear analysis of rheoencephalography might be a useful approach to assess the correlation of cerebral impedance with clinical changesPeer ReviewedPostprint (published version

    ICA-Derived EEG Correlates to Mental Fatigue, Effort, and Workload in a Realistically Simulated Air Traffic Control Task

    Get PDF
    Electroencephalograph (EEG) has been increasingly studied to identify distinct mental factors when persons perform cognitively demanding tasks. However, most of these studies examined EEG correlates at channel domain, which suffers the limitation that EEG signals are the mixture of multiple underlying neuronal sources due to the volume conduction effect. Moreover, few studies have been conducted in real-world tasks. To precisely probe EEG correlates with specific neural substrates to mental factors in real-world tasks, the present study examined EEG correlates to three mental factors, i.e., mental fatigue [also known as time-on-task (TOT) effect], workload and effort, in EEG component signals, which were obtained using an independent component analysis (ICA) on high-density EEG data. EEG data were recorded when subjects performed a realistically simulated air traffic control (ATC) task for 2 h. Five EEG independent component (IC) signals that were associated with specific neural substrates (i.e., the frontal, central medial, motor, parietal, occipital areas) were identified. Their spectral powers at their corresponding dominant bands, i.e., the theta power of the frontal IC and the alpha power of the other four ICs, were detected to be correlated to mental workload and effort levels, measured by behavioral metrics. Meanwhile, a linear regression analysis indicated that spectral powers at five ICs significantly increased with TOT. These findings indicated that different levels of mental factors can be sensitively reflected in EEG signals associated with various brain functions, including visual perception, cognitive processing, and motor outputs, in real-world tasks. These results can potentially aid in the development of efficient operational interfaces to ensure productivity and safety in ATC and beyond

    Fractionation, characterisation and optimisation of refined, bleached and deodorised palm oil using progressive freeze concentration

    Get PDF
    The aims of this experimental work were to study the influence of operating condition on progressive freeze concentration (PFC) of refined, bleached and deodorised palm oil (RBDPO) using coil crystalliser and to determine the optimum condition based on the response of effective partition constant (K) and triglyceride (TG) of olein. The operating condition of circulation flowrate (CF, 2000 to 3000 mL/min), coolant temperature (CTemp, 24 to 29 ºC), circulation time (CTime, 40 to 60 minutes), and initial iodine value (IIV, 50 to 55 wijs) could affect the efficiency of RBDPO fractionation process where mass and heat transfer study and economic analyses were carried out. The results indicated that CF of 2800 mL/min, CTemp of 28 °C, CTime of 60 minutes, and IIV of 55 wijs gave high value of iodine value (IV) and low value of slip melting point (SMP) for olein in the range of 56.97 to 55.84 wijs and 21.57 to 23.04 °C, respectively. The optimization process found that the operating parameter of CF, CTemp and CTime were not significant as indicated by the p value of less than 0.05 from the Pareto chart, meanwhile IIV was significant. Furthermore, the optimum condition for low K and high olein‟s TG found using software assisted response surface methodology (RSM) were in the following range: 2502 to 2537 mL/min for CF, 26 to 27 °C for CTemp, 53 to 54 minutes for CTime, and 56.8 to 56.9 wijs for IIV. For energy and cost analysis, it was found that the fractionation of RBDPO through PFC is cheaper than the conventional fractionation as it has been calculated that the energy usage and production cost for PFC are 0.025465 kW/hr/kg and RM0.03/kg of RBDPO respectively. All the analyses supported the objectives of this study and gave enough evidence of good performance and quality of olein as well as low cost of operation in PFC fractionation

    Aerospace medicine and biology: A continuing bibliography with indexes (supplement 364)

    Get PDF
    This bibliography lists 188 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during June 1992. Subject coverage includes: aerospace medicine and physiology, life support systems and man/system technology, protective clothing, exobiology and extraterrestrial life, planetary biology, and flight crew behavior and performance

    EVALUATING HURRICANE ADVISORIES USING EYE-TRACKING AND BIOMETRIC DATA

    Get PDF
    The cartography of hurricane advisories is challenged with communicating complex information regarding hazards and spatio-temporal uncertainty. This research presents an exploratory geovisualization study assessing how hurricane advisory maps are perceived. In an experimental laboratory setting, study compared student responses to official National Hurricane Center advisory maps and alternative test map products. Research measured human behavioral response and environmental perception using eye-tracking, electroencephalograms (EEG), electrocardiography (ECG), electromyography (EMG), and a survey questionnaire to support analysis of participants' objective and expressed responses to competing geovisualization products. This approach allows the investigation of biometric responses with digital precision in order to infer cartographic design effects on individual map readers.  M.A

    Multiple System Modelling and Analysis of Physiological and Brain Activity and Performance at Rest and During Exercise

    Get PDF
    One of the current interests of exercise physiologists is to understand the nature and control of fatigue related to physical activity to optimise athletic performance. Therefore, this research focuses on the mathematical modelling and analysis of the energy system pathways and the system control mechanisms to investigate the various human metabolic processes involved both at rest and during exercise. The first case study showed that the PCr utilisation was the highest energy contributor during sprint running, and the rate of ATP production for each anaerobic subsystem was similar for each athlete. The second study showed that the energy expenditure derived from the aerobic and anaerobic processes for different types of pacing were significantly different. The third study demonstrated the presence of the control mechanisms, and their characteristics as well as complexity differed significantly for any physiological organ system. The fourth study showed that the control mechanisms manifest themselves in specific ranges of frequency bands, and these influence athletic performance. The final study demonstrated a significant difference in both reaction time and accuracy of the responses to visual cues between the control and exercise-involved cognitive trials. Moreover, the difference in the EEG power ratio at specific regions of the brain; the difference in the ERP components’ amplitudes and latencies; and the difference in entropy of the EEG signals represented the physiological factors in explaining the poor cognitive performance of the participants following an exhaustive exercise bout. Therefore, by using mathematical modelling and analysis of the energy system pathways and the system control mechanisms responsible for homeostasis, this research has expanded the knowledge how performance is regulated during physical activity and together with the support of the existing biological control theories to explain the development of fatigue during physical activity

    A cumulative index to the 1976 issues of a continuing bibliography on Aerospace Medicine and Biology

    Get PDF
    This publication is a cumulative index to the abstracts contained in Supplements 151 through 162 of Aerospace Medicine and Biology: A continuing bibliography. It includes three indexes - subject, personal author, and corporate source

    High School Science Students’ Cognitive Load Using Virtual Reality Compared to Traditional Instruction

    Get PDF
    Cognitive load is the effort needed to process and store information in memory and can be measured via subjective, physiological, and performance methods. Virtual reality learning environments (VRLEs) enhance science aptitude and motivate students to pursue science careers. Cognitive load is divided into three types: intrinsic, extraneous, and germane. Using cognitive load theory as the framework, the problem addressed through this study was that it is not yet fully understood what the effect of VRLEs is on students’ cognitive load, which can hinder their learning if it is too high. Secondary science education comprises many complex topics with significant levels of intrinsic cognitive load. Discovering if VRLEs reduce intrinsic cognitive load without increasing extraneous load, leaving more room for germane cognitive load to aid student processing is crucial. The purpose of this quantitative quasi-experimental study was to determine the difference in cognitive load as measured with the Mental Effort Survey (MES) between high school students who used a VRLE during science instruction for one lesson and students who did not use VRLEs. For this nonequivalent control group design, the data points were derived from high school students who completed Leppink’s MES after a science lesson conducted during the 2021–2022 school year in a private high school in the southwestern United States. The means for each score of the two groups were compared using two-tailed t tests. Results showed a significant decrease in the intrinsic and extraneous load and a significant increase in germane load for the VRLE group. For positive social change results can inform stakeholders about the use of VRLEs and may contribute to academic success, secondary school graduation rates, and employment rates

    Multiple system modelling and analysis of physiological and brain activity and performance at rest and during exercise

    Get PDF
    One of the current interests of exercise physiologists is to understand the nature and control of fatigue related to physical activity to optimise athletic performance. Therefore, this research focuses on the mathematical modelling and analysis of the energy system pathways and the system control mechanisms to investigate the various human metabolic processes involved both at rest and during exercise. The first case study showed that the PCr utilisation was the highest energy contributor during sprint running, and the rate of ATP production for each anaerobic subsystem was similar for each athlete. The second study showed that the energy expenditure derived from the aerobic and anaerobic processes for different types of pacing were significantly different. The third study demonstrated the presence of the control mechanisms, and their characteristics as well as complexity differed significantly for any physiological organ system. The fourth study showed that the control mechanisms manifest themselves in specific ranges of frequency bands, and these influence athletic performance. The final study demonstrated a significant difference in both reaction time and accuracy of the responses to visual cues between the control and exercise-involved cognitive trials. Moreover, the difference in the EEG power ratio at specific regions of the brain; the difference in the ERP components’ amplitudes and latencies; and the difference in entropy of the EEG signals represented the physiological factors in explaining the poor cognitive performance of the participants following an exhaustive exercise bout. Therefore, by using mathematical modelling and analysis of the energy system pathways and the system control mechanisms responsible for homeostasis, this research has expanded the knowledge how performance is regulated during physical activity and together with the support of the existing biological control theories to explain the development of fatigue during physical activity.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
    corecore