Daming Wei
Professor
Wenxi Chen
Associate Professor
Xin Zhu
Assistant Professor
Baikun Wan
Visiting Researcher
Man Luo
Visiting Researcher
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Daming Wei Professor |
Wenxi Chen Associate Professor |
Xin Zhu Assistant Professor |
Baikun Wan Visiting Researcher |
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Man Luo Visiting Researcher |
AY 2010 was the second year of Prof. Wei's grant-in-aid research (Kakenhi) of MEXT in studying derived Electrocardiogram technique in additional leads in diagnosis of the Brugada Syndrome, where Prof. Wei served the representative researcher and Prof. Zhu was a member researcher. In AY 2010, Prof. Wei had two Ph.D. candidates, Mr. Wenfen Shen, and Mr. Xiaolin Zhou, earned Ph.D. degree, where Mr. Shen is the first Ph.D. of Dual-Degree Program in the University of Aizu. Professor Wei served Chairperson of Japan Society of Computerized Electrocardiogram (JSCE) in AY 2010. Supported by all members of the laboratory, Prof. Chen, Prof. Zhu, Ms Mashiko, and students, Prof. Wei successfully organized the 26th workshop of JSCE in Hotel Ristal in Inawashiro Lake. Prof. Wei continued to be a steering committee chair for the IEEE annual meeting of Computer and Information Technology (CIT). The tenth conference in AY 2010 was held in Cyprus. In AY 2010, Prof. Wei had 9 patents registered in Japan and U.S.
Prof. Chen's research activities mainly focused on the ICT-based healthcare domain to pursue a systematic total solution for human healthcare and disease prevention over the whole care cycle. In AY2010, Prof. Chen participated in several funded projects. These projects were heading towards a system development, including a series of instrumentations for seamless and persistent monitoring of vital signs without any disturbance to the subject in daily life environment, and an Internet-based infrastructure. Various vital data were collected using this system over the year to assess the system performance. Various data mining algorithms were developed to allow objective characterization of the subject's health condition change. The final goal is to build a scalable healthcare integrated platform "HSHIP" for lifelong health management and to establish a new discipline "Metrology of Health".
Prof. Zhu's researches were focused on computer simulation of heart and biomedical signal processing. In AY2010, Prof. Zhu conducted the Grants-In-Aid for Scientific Research (No. 21500297) of deriving right precordial leads in the higher intercostal spaces from standard 12 lead ECG for the diagnosis of Brugada syndrome. He also participated the researches in the parallelization of computer simulation of ECG using multi-core CPU and general-purpose GPU, the computer simulation of atrial fibrillation, and the long-term monitoring of heart rate, respiration rhythm, and body movement.
Wenfeng Shen, Daming Wei, Weimin Xu, Xin Zhu, and Shizhong Yuan. Parallelized computation for computer simulation of electrocardiograms using personal computers with multi-core CPU and generalpurpose GPU. Computer Methods and Programs in Biomedicine, 100(1):87 96, October 2010.
Biological computations like electrocardiological modelling and simulation usually require high-performance computing environments. This paper introduces an implementation of parallel computation for computer simulation of electrocardiograms (ECGs) in a personal computer environment with an Intel CPU of Core (TM) 2 Quad Q6600 and a GPU of Geforce 8800GT, with software support by OpenMP and CUDA. It was tested in three parallelization device setups: (a) a four-core CPU without a general-purpose GPU, (b) a general-purpose GPU plus 1 core of CPU, and (c) a four-core CPU plus a general-purpose GPU. To effectively take advantage of a multi-core CPU and a general-purpose GPU, an algorithm based on load-prediction dynamic scheduling was developed and applied to setting (c). In the simulation with 1600 time steps, the speedup of the parallel computation as compared to the serial computation was 3.9 in setting (a), 16.8 in setting (b), and 20.0 in setting (c). This study demonstrates that a current PC with a multi-core CPU and a general-purpose GPU provides a good environment for parallel computations in biological modelling and simulation studies.
Shizhong Yuan, Daming Wei, and Weimin Xu. An Architecture for Cross-hospital Access to Electrocardiogram Data. Telemedicine and e-Health, accepted, 2010.
Owing to a lack of easy access to an individual's electrocardiogram (ECG) data that may be distributed across multiple hospitals, medical practice using serial ECG analysis has not so far been extensively used. Motivated to address this problem, we design and implement an architecture for cross-hospital access to ECG data. The architecture provides a Web portal for retrieving a particular patient's ECG data distributed across a number of ECG data sources. Two important features of this architecture are (1) the distributed search mechanism that uses a master patient index to determine what ECG data sources are likely to contain the ECG data pertaining to a specified patient and (2) the Web servicedata pertaining to a specified patient and (2) the Web service?based interoperable based interoperable method for accessing disparate ECG data sources. We show that the architecture provides an effective search and retrieval facility for cross-hospital access to ECG data; we show this by implementing and employing a prototype in an experimental scenario consisting of two disparate ECG data sources located at two sites. Our study demonstrates a significant effort to improve the ease of cross-hospital access to ECG data.
Weijia Lu, Cuiwei Yang, Zuxiang Fang, Xingpeng Liu, Xin Zhu, and Daming Wei. Implementation of a Novel Interpolating Method to Epicardial Potential Mapping for Atrial Fibrillation Study. Computersin Biology and Medicine, 40(4):456-463, April 2010.
Epicardial potential mapping is an efficient way to visualize the potential distribution on the epicardial surface. We found in our previous study, that the traditional linear interpolation used for the epicardial mapping may cause errors and distortions in reconstruction of the electric activities on the epicardial surface especially during the atrial fibrillation. In this study, we devoted on the implementation of a 3D interpolating method, and verified it in comparison with another interpolating method as well as studying of the mechanism of vagal atrial fibrillation (AF). In case studying, we analyzed the epicardial data from seven canine cardiac models using this method and found the macro-re-entry during the sustainable AF is more likely due to the dispersion of refractoriness in the myocardium and does not demonstrated the focal patterns at the beginning of AF. This indicated that the electrophysiological characteristics of myocardium might have been changed during the paroxysmal atrial fibrillation (PAF).
Xin Zhu, Wenxi Chen, Tetsu Nemoto, Kei ichiro Kitamura, and Daming Wei. Long-term monitoring of heart rate, respiration rhythm, and body movement during sleep based upon a network. Telemedicine and e-Health, 16(2):244-253, 2010.
A method for accurately recording heart rate (HR), respiration rhythm (RR), and body movement (BM) during sleep using a network-based system is proposed in this article. Its application to the long-term monitoring of HR, RR, and BM during sleep was examined. HR, RR, and BM were detected by pressure variations corresponding to changes in the heartbeat and respiratory motion, which were measured by a sensor unit placed beneath a pillow during sleep under completely unconstrained conditions. The pressure signals were digitized and transmitted to a remote database server using transmission control protocol (TCP)/Internet protocol (IP) via a netbox. In the server, the data were processed to obtain HR, RR, and BM. The overall performance of the system was examined using data collected over a 13-month period from a female subject. Besides the long-term profiles of HR, RR, and the periods during which the HR and RR were undetectable owing to BMs during sleep, the average frequency of BM in a day varied from 4.4 to 22.4/h, and the mean frequency over 332 nights was 8.3/h with a standard deviation of 2.2/h. Periodic biorhythms can also be assessed using the profiles of the average HR and certain frequency-domain parameters of HR variability. The rhythmic property of these profiles was confirmed to coincide with the subject's menstrual cycle. The results of this 13-month trial operation show that this system can be installed in the home environment; used to monitor HR, RR, and BM during sleep; and analyze various physiological rhythms in humans over prolonged periods.
Kei-ichiro Kitamura, Wenxi Chen, Xin Zhu, Nobuo Suzuki, Sachiko Yano, and Tetsu Nemoto. Acceleration-based study of optimum exercise for human weight-bearing bones enhancement. Biological Science in Space, 24(2):83-90, 2010.
Physical activity is known to enhance the mechanical competence of bones. However,previous related studies provide little information regarding the optimum exercises for the prevention of osteoporosis in the lumbar region, including the hip joints. Physicalactivities can be evaluated by simultaneously collecting acceleration data from accelerometers worn on different parts of the body. We attached three triaxial accelerometers to the ankle, knee, and lumbar points of 20 young women subjects in order to perform acceleration measurements while walking (a flat surface and a stairway) and jumping rope. The acceleration at the lumbar point while walking a flat surface, ascending stairs, and descending stairs were 1.96 ± 0.28, 1.92 ± 0.29, and 2.88 ± 0.66G, respectively. On the other hand, jumping rope provided an acceleration of 5.4G at the lumbar point. This value is higher than the threshold acceleration necessary to induce an osteogenic response in the lumbar region of young subjects, namely 3.5G. Descending stairs provided the second-highest intensity of acceleration in the lumbar region; however, it also produced excess impact acceleration at the ankle and knee points. Jumping rope, in contrast, provided sufficient intensity of acceleration in the lumbar region, but the acceleration imparted to the ankle and knee points remained at a tolerable level. Moreover, correlation analyses of the acceleration at the ankle, knee, and lumbar points during each physical activity showed that the knee joints solely regulated the strong landing impact force while the subjects were descending the flight of stairs. In comparison, while jumping rope, the ankle and hip joints regulated the large landing impact force cooperatively, without overloading themselves. Our results suggest that jumping rope can provide sufficient acceleration to induce an osteogenic response in the lumbar region without causing an overload to any joints. Thus, jumping rope is one of the most optimum exercises for bone mineral gain in the proximal femur and lumbar vertebrae regions in young subjects.
Kei-Ichiro Kitamura, Xin Zhu, Wenxi Chen, and Tetsu Nemoto. Development of a new method for the noninvasive measurement of the core body temperature without a heater. Medical Engineering & Physics, 32(1):1-6, January 2010.
The conventional zero-heat-flow thermometer, which measures the deep body temperature from the skin surface, is widely used at present. However, this thermometer requires considerable electricity to power the electric heater that compensates for heat loss from the probe; thus, AC power is indispensable for its use. Therefore, this conventional thermometer is inconvenient for unconstrained monitoring. We have developed a new dual-heat-flux method that can measure the deep body temperature from the skin surface without a heater. Our method is convenient for unconstrained and long-term measurement because the instrument is driven by a battery and its design promotes energy conservation. Its probe consists of dual-heat-flow channels with different thermal resistances, and each heat-flow-channel has a pair of IC sensors attached on its top and bottom. The average deep body temperature measurements taken using both the dual-heat-flux and then the zero-heat-flow thermometers from the foreheads of 17 healthy subjects were 37.08 degrees C and 37.02 degrees C, respectively. In addition, the correlation coefficient between the values obtained by the 2 methods was 0.970 (p0.001). These results show that our method can be used for monitoring the deep body temperature as accurately as the conventional method, and it overcomes the disadvantage of the necessity of AC power supply.
Wenxi Chen. Healthcare - an everlasting challenge in temporal and spatial domains. Journal of Multidisciplinary Healthcare, pages 189-199, 2010.
Health care is an everlasting challenge that requires effort at all levels, from national and organizational to individual domains, over a long-term period. This article reviews the historical development of health care-related issues worldwide and accentuates the necessity of health care in the current era. Through investigating the historical background in both the occidental and the oriental worlds and the latest achievements from academic and industrial endeavors, many lessons can be learnt, and as a result, an integrative strategy is proposed to meet today's pressing needs. A government-funded project, `Challenge to 100 years of age', which involved more than 600 residents in west Aizu village, lasted over 15 years. After reviewing its outcomes, a metrology of health based upon the three-dimensional phase space, which integrates with social well-being, mental status, and physical condition for a lifelong span, is advocated as a measure of the holistic view of health state.
Weijia Lu, Cuiwei Yang, Zuxiang Fang, Xingpeng Liu, Xin Zhu, and Daming Wei. Development of a new method for the noninvasive measurement of deep body temperature without a heater. Medical Engineering & Physics, 40(4):456-463, April 2010.
Epicardial potential mapping is an efficient way to visualize the potential distribution on the epicardial surface. We found in our previous study, that the traditional linear interpolation used for the epicardial mapping may cause errors and distortions in reconstruction of the electric activities on the epicardial surface especially during the atrial fibrillation. In this study, we devoted on the implementation of a 3D interpolating method, and verified it in comparison with another interpolating method as well as studying of the mechanism of vagal atrial fibrillation (AF). In case studying, we analyzed the epicardial data from seven canine cardiac models using this method and found the macro-re-entry during the sustainable AF is more likely due to the dispersion of refractoriness in the myocardium and does not demonstrated the focal patterns at the beginning of AF. This indicated that the electrophysiological characteristics of myocardium might have been changed during the paroxysmal atrial fibrillation (PAF).
Xin Zhu, Wenfeng Shen, Daming Wei, Weimin Xu, Shizhong Yuan, and Qun jin. Parallelization of cardiac computer simulation based on multi-core CPU and General-purpose GPU. In Proceedings of the 6th Annual Meeting of Japanese Society for Computerized Electrocardiology, page 36, Inawashiro, Japan, 2010.
A high-performance computer system is essential for cardiac modeling and computer simulation. Traditional systems for cardiac modeling and cardiac simulation are cluster computers composed of workstations. On the other hand, with the implementation of Multi-core CPU (Central Processing Unit) and General-purpose GPU (Graphics Processing Unit), it is possible use personal computers equipped with Multi-core CPU and General-purpose GPU for the parallel scientific computation. In this research, by employing personal computers with a 4-core CPU and General-purpose GPU, and two development tools: OpenMP and CUDA, we re alized the parallel computation of cardiac computer simulation based Wei-Harumi model. Compared with the computation result of a traditional personal computer, the computation time for cardiac computer simulation was reduced to 5% by using 4-core CPU and General-purpose GPU. Therefore, a computer equipped with multi-core CPU and General-purpose GPU can serve as a low-cost and high-performance computation system for the high speed and parallel computation of cardiac computer simulation.
Masaru Tasaki, Motoaki Sakai, Mai Watanabe, Hui Wang, and Daming Wei. Evaluation of Drowsiness during Driving using Electrocardiogram. In Proceedings of the 10th IEEE International Conference on Computer and Information Technology (CIT 2010), pages 1480-1485, 2010.
Drowsiness during driving causes traffic accidents frequently. It is therefore desirable to detect the drowsiness. Drowsiness occurs when the parasympathetic nerve activity becomes dominant. Related researches show that high frequency (HF) component of heart rate variability (HRV) on an electrocardiogram (ECG) has certain correlation with drowsiness by reflecting the parasympathetic nerve activity. In this study, the driving experiments were conducted with a simulator, where the ECG was recorded, and the heartbeat intervals were calculated. The power spectrum of HRV was analyzed by Fast Fourier Transform (FFT), and the temporal change of HF band was analyzed. In addition, low frequency (LF) to HF ratio (LF/HF), which is considered an indicator for the sympathetic nervous system, was also investigated. The results show that in the data of six out of ten experiments, the correlation among subjective drowsiness, HF is high. Some experimental results also show positive correlation between subjective drowsiness and LF/HF.
Wenhao Zhu, Shunlai Bai, Bofeng Zhang, Weimin Xu, and Daming Wei. An Information Extraction Method for Digitized Textbooks of Traditional Chinese Medicine. In Proceedings of the 10th IEEE International Conference on Computer and Information Technology (CIT 2010), pages 1645-1648, 2010.
Digital libraries have shouldered the mission of preserving and spreading human culture in the era of information. However, knowledge extraction for digital libraries is not well studied, and that holds back the role promotion of digital libraries from information collector to knowledge provider. This paper presents an ontologybased approach, which extracts detailed attributes of Traditional Chinese Medicine (TCM) from digitized textbooks. According to the characters of digitized textbooks, we propose an extraction ontology that is compatible with both textbook extraction and TCM theory. To improve extraction tolerance for OCR errors, we extract features of different aspects. Finally, a structured pattern based extraction method is adopted to minimize extraction supervision. The result shows that our method is a practical and robust exploration to address the problem of information extraction for digitized textbooks of TCM.
Shaochun Wu, Tongyu Yuan, Mingdong Li, Bofeng Zhang, and Daming Wei. Geomagnetic Precursor Diurnal Phase Anomaly Recognition
based on the Pattern Distance. In Proceedings of the 10th IEEE International Conference on Computer and Information Technology (CIT 2010), pages 1229 1234, Bradford, 2010. Geomagnetic precursor is one of many earthquake precursors, which have better effects on earthquake prediction, while the diurnal variation anomaly of geomagnetic precursor Z component is an important one in short-impending anomalies. Basing on the pattern distance of geomagnetic precursor Z component diurnal variation, this paper proposes an anomaly recognition algorithm which combines the feature of geomagnetic precursor data with time series similarity measure. We validate the effectiveness of the algorithm through the actual data.
Xiaolin Zhou, Xin Zhu, Hui Wang, and Daming Wei. Measurement of QT IntervalProlongation: a Comparative Evaluation of Six Algorithms Using Simulated Electrocardiograms. In Proceedings of IEEE Region 10 Conference, TENCON2010, pages 2077 2082, Fukuoka, Japan,, November 2010.
While measurement of QT prolongation in electrocardiogram (ECG) is important to clinical applications, but it is difficult to quantitatively evaluate the performance of QT measurement algorithms using clinical ECGs because the true values of the QT changes are usually unknown. In this paper, we report a comparative study to evaluate the performance of the six algorithms for QT interval prolongation measurement with computer-simulated ECGs based on a whole-heart model. Artificial zero-mean Gaussian noise with variable signal-to-noise ratios (SNR) was added to the simulated ECGs for quantitative evaluation of these algorithms with variations thresholds. The study showed that, the measurement accuracies of these six methods augment with the increase of the SNR of simulation data, while the variations of threshold of these methods have little influence on the measurement accuracy of QT interval variation. Through evaluating the QT interval prolongation values measured from the same simulated ECGs contaminated with noises, the best performance was obtained from the continuous wavelet transform based method with the mean error less than 1 ms even when the SNR is as low as 0 dB. Our study suggests that the continuous wavelet transform based method may outperform the traditional methods in estimating QT interval prolongation for ECGs with strong noise as evaluated with artificial ECGs.
Yi Zheng, Daming Wei, and Zuxiang Fang. Steeper Action Potential Duration Restitution Slope Increases Risk of Ventricular Fibrillation: A Simulation Study. In Proceedings of International Conference on Bioinformatics and Biomedical Engineering (iCBBE 2010), pages 1 4, Chengdu, PRC, 2010.
Action potential duration restitution (APDR) is thought to be relevant to the stability of cardiac electrophysiology. Ventricular fibrillation (VF) was simulated using the Wei-Harumi model by taking into account piecewise linear action potential duration restitution based on clinical findings. We found, in the simulation, that heart model with steeper slope of APDR required less ectopic stimuli to trigger VF. This result suggested that the APDR may affect cardiac vulnerability to VF.
Xin Zhu, Osamu Okazaki, and Daming Wei. Derivation of right precordial leads in the higher intercostal spaces for the diagnosis of Brugada syndrome: preliminary study based on computer simulation. In Proceedings of 27th Annual Meeting of the Japanese Society of Electrocardiology, Vol. 30, Suppl. 4, page 206, September 2010.
Goal: Right precordial leads in the higher intercostals is useful for the diagnosis of Brugada syndrome when coved-type ST elevation cannot be observed in the standard V1 and V2 leads. In this research, we proposed a method to derive right precordial leads in the higher intercostals from standard 12 lead ECG, and used the simulated ECG based on Wei-Harumi model for evaluation. Method: Evaluation data: The enlarged notch in the 1st phase and reduced action potential in the 2nd and 3rd phases are set for the epicardium cell in the RVOT (right ventricular outflow trait) of Wei-Harumi model in order to reproduce the repolarization transmural heterogeneity. Based on this model, we simulated the coved-type right precordial leads, and the corresponding standard V1 and V2 leads only demonstrate type 2 and type 3 Brugada ECG. Derivation method: Based on the information redundancy in the 12-lead system and the least square method, we proposed a method to derive right precordial leads in the higher intercostals from standard 12 lead ECG. Result and conclusion: Based on the proposed method, we derived right precordial leads in the higher intercostals from the simulated standard 12 lead ECG. The derived ight precordial leads in the higher intercostals illustrates J wave and covedtype ST elevation: the characteristic waveform of Brugada syndrome. Our method may be serve as an assistant diagnostic tool for the screening of Brugada syndrome.
Yi Zheng, Daming Wei, Zuxiang Fang, and Xin Zhu. Influences of Sites and Protocols on Inducing Ventricular Fibrillation: a Computer Simulation Study. In Proceedings of Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBS 2010), pages 2005-2008, 2010.
In cardiac electrophysiological study, several electrical stimulation protocols have been employed to induce ventricular fibrillations (VF). In addition, sites of inducing may have different impacts on inducing results as well as different inducing protocols. To study whether VF inducing method is determinant of induced outcome, we simulated VFs induced with different protocols at different sites based on the Wei-Harumi whole heart model. Simulations showed that only certain combinations of pacing protocols and sites could induce sustainable VFs, which had similar frequency distributions. This result suggested that the interactions between protocols and sites determine the odds of successful inducing but once the VF was induced, the pattern was solely determined by inner cardiac properties.
Xin Zhu, Daming Wei, and Osamu Okazaki. Derived right precordial leads at higher intercostals spaces from 12-lead system for diagnosis ofBrugada syndrome. In Proceedings of the 32nd IEEE EMBS Annual Conference, pages 2581-2584, Buenos Aires, 2010.
Recording the right procordial leads at higher intercostal spaces (ICS) can raise the sensitivity of the diagnosis on Brugada syndrome using ECG. However, the directive measurement of the right precordial leads at the higher ICSs is tedious and impractical. In this paper, we proposed a derivation method based on the information redundancy in the 12-lead system to study the possibility of deriving the right precordial leads at the higher ICSs from the commonly used Mason-Likar 12-lead ECGs. Through the evaluation based on the simulated Brugada-type ECGs and recorded ECGs from BS subjects, we found that the BS characteristic J wave and coved type ST elevation in the right precordial leads at the higher ICSs could be satisfyingly derived from the 12-lead ECGs. It is concluded that the derived precordial leads at the higher ICSs may serve as an assistant diagnosis tool to unmask Brugada syndrome.
Susu Jiang, Bofeng Zhang, Weimin Xu, and Daming Wei. Gait Symmetry Analysis Based On Affinity Propagation Clustering. In Proceedings of the 10th IEEE International Conference on Computer and Information Technology (CIT 2010), pages 1673-1678, 2010.
When we are conducting an investigation in gait symmetry analysis, we usually grouped the test objects by decade intervals. However, this artificial division method has a large defect that does not truly reflect the human relationship between age and physical condition. Therefore, we found a new grouping method while clustering on the values of the difference in gait symmetry. The reason for using the affinity propagation clustering algorithm was that it can do clustering on data while passing the original information not the random values to processing clustering. And meanwhile this algorithm has good performance and efficiency. It will help us to do gait analysis more effectively, and also more reasonable to explain the relationship of human gait and age, or gait and other characteristics.
Xin Zhu, Wenxi Chen, Tetsu Nemoto, Kei ichiro Kitamura, and Daming Wei. Analysis of pulse rate, respiration rhythm, and body movement during sleep detected by pressure sensor. In Proceedings of the 2nd International Symposium on Aware Computing (ISAC), pages 213-219, Nov. 2010.
We have proposed a network based system for long-term recording pulse rate (PR), respiration rhythm ( RR), and body movement (BM) detected by a sensor unit placed beneath a pillow during sleep from pressure variations corresponding to changes in the heartbeat and respiratory motion. In this research, we studied the analysis of the long-term monitored PR, RR, and BM during sleep recorded by this system. Using data collected over a 13-month period from a female subject, the average frequency of BM in a day varied from 4.4 to 22.4 h-t, and the mean frequency of BM over 332 nights was 8.3 h-I with a standard deviation of 2.2 h-I Periodic biorhythms were also assessed using the profiles of the average PR and certain frequency domain parameters ofPR variability. The rhythmic property of these profiles was confirmed to coincide with the subject's menstrual cycle. The results of this 13-month trial operation show that it is possible to long-term monitor PR, RR, and BM during sleep by using our system, and analyze various physiological rhythms in humans over prolonged periods.
Wenxi Chen, Masumi Kitazawa, and Tatsuo Togawa. Identification of Biphasic Property in Female Menstrual Cycle from Oral, Skin and Core
Body Temperatures. In Proc. of the 10th International Conference on Information Technology and Applications in Biomedicine (ITAB2010), page 4, Corfu, Greece, 2010. CDROM. Biphasic property in female body temperature during menstrual cycle is estimated by a discrete Hidden Markov Model (HMM)-based approach. Estimation procedure includes three steps - preprocessing, HMM-based main processing and postprocessing. The HMM is supposed to have two hidden phases to describe the biphasic property in body temperature during a menstrual cycle. Three kinds of different body temperature data were collected daily from four female volunteers over six months. Skin and core body temperatures were measured at intervals of ten and four minutes respectively and automatically by two separated wearable devices during sleep. Oral basal body temperature was measured in the morning right after wakeup. Estimation results of biphasic property from different body temperatures were evaluated by quantifying the alignment between estimated phase transitions and volunteers' menstruation records. Results showed that the estimation performance, in terms of sensitivity and positive predictability, varies with different kind of body temperature. Among 21 menstrual cycles in four participants during six months, both overall sensitivity and positive predictability of estimation by oral basal body temperature reach the highest 95.2%; those of skin body temperature have the lowest 81.0% and 77.3%, respectively; while those of core body temperature are 90.5% and 82.6%, respectively, straddling between oral and skin body temperatures.
Ying Chen and Wenxi Chen. Seasonal Chaotic Features of Pulse Rate in a Healthy Subject and a Patient after Coronary Stenting. In Proc. of the 32nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC10), pages 2549-2552, Buenos Aires, Argentina, August 31-Sept. 4 2010.
This study analyzes seasonal features of pulse rate chaos in both healthy and unhealthy subjects. Analytical methods, such as numerical titration, sample entropy and spectral analysis, were used to detect and estimate the seasonal fluctuations in chaotic attributes, complexity and nonlinearity of pulse rate. Chaotic feature analyses are based on pulse rate data collected over one year from a healthy male and a male patient after coronary stenting. The results show that the mean level of pulse rate chaos in the healthy subject is lowest in winter (values of NL, DR, and SampEn are 8.1 ± 0.3%, 41.0 ± 1.2%, and 1.98 ± 0.02, separately) and highest in summer (corresponding values are 9.9 ± 0.6%, 46.8 ± 2.3%, and 2.06 ± 0.03, separately) (P < 0.05), whereas the postoperative individual has a relatively lower mean chaotic dynamics that is least active in autumn (7.1 ± 0.5%, 14.8 ± 1.5%, and 0.80 ± 0.01) and more active in winter (7.7 ± 0.4%, 35.9 ± 1.9%, and 0.93 ± 0.01) and spring (9.1 ± 0.7%, 28.6 ± 2.1%, and 0.87 ± 0.01) (P < 0.05). The study reveals distinct seasonal autonomic and cardiac activities in both good health and disease. These findings may also pave the way for developing new approaches to monitoring long-term HRV and interpreting HRV chaotic features.
Ming Huang and Wenxi Chen. Theoretical Simulation of the Dual-HeatFlux Method in Deep Body Temperature Measurements. In Proc. of the 32nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC10), pages 561-564, Buenos Aires, Argentina, August 31-Sept. 4 2010.
Deep body temperature reveals individual physiological states, and is important in patient monitoring and chronobiological studies. An innovative dual-heat-flux method has been shown experimentally to be competitive with the conventional zero-heat-flow method in its performance, in terms of measurement accuracy and step response to changes in the deep temperature. We have utilized a finite element method to model and simulate the dynamic process of a dual-heat-flux probe in deep body temperature measurements to validate the fundamental principles of the dualheat-flux method theoretically, and to acquire a detailed quantitative description of the thermal profile of the dual-heat-flux probe. The simulation results show that the estimated deep body temperature is influenced by the ambient temperature (linearly, at a maximum rate of 0.03 ℃/ ℃) and the blood perfusion rate. The corresponding depth of the estimated temperature in the skin and subcutaneous tissue layer is consistent when using the dual-heat-flux probe. Insights in improving the performance of the dual-heat-flux method were discussed for further studies of dual-heat-flux probes, taking into account structural and geometric considerations.
Zhaoqin Liu, Linlin Jiang, Wenxi Chen, and Tetsu Nemoto. Performance Assessment on Different Measurement Positions for Monitoring HR/RR during Sleep. In Proc. of the 32nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC10), pages 3831-3834, Buenos Aires, Argentina, August 31-Sept. 4 2010.
This study aims to investigate the measurement performance on different sensor deployment and to determine the optimal position for monitoring heart rate (HR) and respiration rate (RR) during sleep. Five identical sensor boards were deployed on different positions simultaneously during sleep to detect changes of applied pressure due to heart beating and breathing. One board was set beneath the pillow; the other four boards were set under the mattress aligning with the head, back, hip and calf, respectively. Data were collected from five healthy subjects during a 2-hour's nap individually. Detection performance was evaluated by sensitivity and positive predictivity. The results showed that nearly all of the positions could be used to detect heart rate; both sensitivity and positive predictivity were over 85% among five persons. All of the positions could be used to detect respiration rate except for calf. The highest performance of sensitivity and positive predictivity in respiration rate detection could be found in the hip position, which reached as high as 99%. The optimal position with overall best performance for HR and RR measurement is considered in the hip. property of these profiles was confirmed to coincide with the subject's
Ming Huang and Wenxi Chen. The Inverse Problem of Deep Body Temperature Monitoring in Human Abdominal Phantom. In Symposium on Inverse Problems in Biomedical Engineering, Tokyo, Nov. 2010.
Deep body temperature is the functioning temperature of organs, and specifically, the temperature of the internal organs in the abdominal, thoracic, and cranial cavities. The circadian rhythm of the deep body temperature contains abundant information, which reveals individual physiological states, and is important in patient monitoring and chronobiological studies. Many different methods have been developed for measuring temperatures deep inside the body. However, invasive methods have been shown unsuitable for long-term temperature monitoring. The main problem of these readymade methods is that, they give the estimation of the deep body temperature without a specific location inside human body. Namely, we don't know which part inside human body does the temperature value corresponding to. The purpose of this paper is to find out a new method which can provide us more information about the temperature distribution inside human body just from the outside temperature measurement. In term of the inverse problem, the aim is to reconstruct the model from a set of parameters (unknowns) with a set of data (measurements). In our problem, the temperature measurements are carried out on the skin surface with temperature sensors, the parameters (unknowns) are the temperature values of the specific apparatuses inside human's abdomen.
Ying Chen and Wenxi Chen. Estimation of the Seasonal Biorhythms Based on Pulse Rate during Sleep. In Proc. of the 49th Annual Conference of Japanese Society for Medical and Biological Engineering, Osaka, Japan, June 2010.
The Poincar plot describes nonlinear dynamics of cardiovascular system and portrays the oscillatory nature of heart action. A normal pattern of Poincar plot presents a visible phenomenon of asymmetry which reflects a healthy physiological system. Our study aims to investigate whether this asymmetry is constant throughout the year or varies with the season. Pulse rate data were recorded from a 30's healthy woman during her daily sleep over one year period. The first 6000 RR intervals of each night data were studied. Six quantitative asymmetry descriptors, SD1up, SD1down, SD1up/SD1down, Cup, Cdown, and Cup/Cdown, were defined to refer to contributions and relative contributions from the points above and below the minor axis and their ratios. The result shows that there is a statistically seasonal change of asymmetry in Poincar plot where the asymmetry is most significant in summer and the least in autumn and winter.
Ming Huang, Wenxi Chen, and Tetsu Nemoto. Core Temperature Rhythm of Bedridden Patients with Sequelae of Cerebral Infarction. In Proc. of the 49th Annual Conference of Japanese Society for Medical and Biological Engineering, Osaka, Japan, June 2010.
Circadian rhythm in core temperature was reported ambiguous in the bedridden patients with neurodegenerative diseases and sequelae of cerebral infarction who are suffering from sleep disorder and motor disturbance. This study is to find out whether there are rhythmic disorders in core temperature in bedridden patients who are suffering from the sequelae of cerebral infarction. By using a zero-heat-flow deep body thermometer, core temperature data were collected in 6 bedridden patients (aged from 77 to 96 years old, 2 males and 4 females) with sequelae of cerebral infarction. For each patient, 2 whole days' data were employed by cosinor analysis to reveal the biorhythm's features. The result shows that the mean and the standard deviation of the mesors among 6 patients are 36.55 ℃ and 0.18 respectively and suggests that there are 6 hours and 12 hours cycle components in this kind of patients.
Hiroo Watanabe and Wenxi Chen. Detection of Daily Life Style Change from Pulse Rate Measured during Sleep. In Proc. of the 49th Annual Conference of Japanese Society for Medical and Biological Engineering, Osaka, Japan, June 2010.
Sleep is necessary to maintain good health. A convenient sleep monitor for home use is desired. This research developed a network-based system for daily sleep monitoring at home, and an algorithm for detecting changes in daily life style. This system consists of a home station and a database server. The home station measures pulse rate (PR) and saturation of peripheral oxygen (SpO2) using a Bluetooth-enabled pulse oximeter, "Onyx II 4100" (NONIN Corp, USA). The oximeter sends the data to a PC by Bluetooth wireless connection during sleep. The PC transmits the data to database server by HTTP connection. The database server manages the data and minimizes noise by median filter and least-mean-square filter and creates PR profile. The server creates various charts from the retrieved data.
Wenxi Chen. Automatic Estimation of Female Menstrual Cycle from Body Temperature and Heart Rate. Number 105-107. Jugatsu Sya,, Tokyo , Japan, 5 2010.
Book title: Column 6 in 'More About Basal Body Temperature' Edited by: Matsumoto Seiichi ISBN 9784434144981
Wenxi Chen. Estimation of Female Menstrual Cycle from Heart Rate during Sleep, 2008-2011.
Principal Investigator JSPS Grants-In-Aid for Scientific Research (20500601), 3.64 mJPY (2010FY=700+210k)
Wenxi Chen. Sleep Monitoring System, 2009-2010.
IP provider and Co-researcher Ministry of Internal Affairs and Communications, 17 mJPY
Xin Zhu, 2010.
Session Chair of IEEE ISAC2010
Xin Zhu, 2010.
Technical chair of 26th Annual Meeting of Japanese Society for Computerized Electrocardiology
Wenxi Chen, Daming Wei, and Naotoshi Takeda. VITAL SIGN PROCESSING SYSTEM, Nov. 2010.
Wenxi Chen, Daming Wei, Shigeru Tokinoya, and Naotoshi Takeda. SENSOR BELT FOR VITAL SIGN MONITORING, Nov. 2010.
Wenxi Chen and Daming Wei. BODY STATUS MONITORING DEVICE, 2010.
Shegeru Tokinoya, Wenxi Chen, and Daming Wei. INSTANT REUSABLE ELECTRODE DEVICE, Jan. 2011.
Hiroo Watnabe. Master Thesis: Detection of Daily Life Style Change from Pulse Rate Measured during Sleep, Graduate School of Computer Science and Engineering, March 2011.
Thesis Adviser: Wenxi Chen
Tsuyoshi Matsuzawa. Graduation Thesis: Effect of Ambient Temperature and Humidity on Heart Rate and Respiration Rate during Sleep, School of Computer Science and Engineering, March 2011.
Thesis Adviser: Wenxi Chen
Xiaolin Zhou. PhD Thesis: Computer Algorithm for Measurement of QT Interval Prolongation in Electrocardiograms, Graduate School of Computer Science and Engineering, March 2011.
Doctoral Thesis Review (Co-Referees)
Wataru Ueda. Graduation Thesis: Analysis of Daily Lifestyle Change Based on Lorenz Plot of Pulse Rate Measured during Sleep, School of Computer Science and Engineering, March 2011.
Thesis Adviser: Wenxi Chen
Norbert Gyrbr. PhD Thesis: Interaction Methods for Recording and Recollecting Personal Experiences, Graduate School of Computer Science and Engineering, March 2011. Doctoral Thesis Review (Co-Referees)
Koji Yamada. Master Thesis: iPhone-based Ubiquitous Monitor for Fetal Heart Rate, Graduate School of Computer Science and Engineering, March 2011.
Thesis Adviser: Wenxi Chen
Wenfeng Shen. PhD Thesis: Parallelization for High Performance Computing in Computer Simulation of Electrocardiogram, Graduate School of Computer Science and Engineering, September 2010. Doctoral Thesis Review (Co-Referees)
Wenxi Chen. UBIC adjunct member, 2010.
Wenxi Chen. GSAAC member, 2010.
Wenxi Chen. Aizu industry network forum ANF member, 2010.
2011 THE UNIVERSITY OF AIZU ALL RIGHTS RESERVED