Model validation for a noninvasive arterial stenosis detection problem

Copyright @ 2013 American Institute of Mathematical SciencesA current thrust in medical research is the development of a non-invasive method for detection, localization, and characterization of an arterial stenosis (a blockage or partial blockage in an artery). A method has been proposed to detect shear waves in the chest cavity which have been generated by disturbances in the blood flow resulting from a stenosis. In order to develop this methodology further, we use both one-dimensional pressure and shear wave experimental data from novel acoustic phantoms to validate corresponding viscoelastic mathematical models, which were developed in a concept paper [8] and refined herein. We estimate model parameters which give a good fit (in a sense to be precisely defined) to the experimental data, and use asymptotic error theory to provide confidence intervals for parameter estimates. Finally, since a robust error model is necessary for accurate parameter estimates and confidence analysis, we include a comparison of absolute and relative models for measurement error.The National Institute of Allergy and Infectious Diseases, the Air Force Office of Scientific Research, the Deopartment of Education and the Engineering and Physical Sciences Research Council (EPSRC)

Wireless transmission of biosignals for hyperbaric chamber applications

[EN] This paper presents a wireless system to send biosignals outside a hyperbaric chamber avoiding wires going through the chamber walls. Hyperbaric chambers are becoming more and more common due to new indications of hyperbaric oxygen treatments. Metallic walls physically isolate patients inside the chamber, where getting a patient's vital signs turns into a painstaking task. The paper proposes using a ZigBee-based network to wirelessly transmit the patient's biosignals to the outside of the chamber. In particular, a wearable battery supported device has been designed, implemented and tested. Although the implementation has been conducted to transmit the electrocardiography signal, the device can be easily adapted to consider other biosignals.The authors would like to thanks the University of Balearic Islands (UIB), the Miguel Hernandez University (UMH), MEDIBAROX unit of the Perpetuo Socorro Hospital and the "Catedra de Medicina Hiperbarica" (UMH) for their support allowing the use of its facilities for this work. The authors would also like to thank Borja Mas Boned for his help designing the LabVIEW application. This research has been carried out with funding and promotion of "Catedra de Medicina Hiperbarica" of the Miguel Hernandez University. http://nbio.umh.es/es/2010/12/01/catedra-de-medicina-hiperbarica-medibarox/.Perez-Vidal, C.; Gracia Calandin, LI.; Carmona, C.; Alorda, B.; Salinas, A. (2017). Wireless transmission of biosignals for hyperbaric chamber applications. PLoS ONE. 12(3):1-19. https://doi.org/10.1371/journal.pone.0172768S119123Sureda, A., Batle, J. M., Martorell, M., Capó, X., Tejada, S., Tur, J. A., & Pons, A. (2016). Antioxidant Response of Chronic Wounds to Hyperbaric Oxygen Therapy. PLOS ONE, 11(9), e0163371. doi:10.1371/journal.pone.0163371Branco, B. H. M., Fukuda, D. H., Andreato, L. V., Santos, J. F. da S., Esteves, J. V. D. C., & Franchini, E. (2016). The Effects of Hyperbaric Oxygen Therapy on Post-Training Recovery in Jiu-Jitsu Athletes. PLOS ONE, 11(3), e0150517. doi:10.1371/journal.pone.0150517Xu, Y., Ji, R., Wei, R., Yin, B., He, F., & Luo, B. (2016). The Efficacy of Hyperbaric Oxygen Therapy on Middle Cerebral Artery Occlusion in Animal Studies: A Meta-Analysis. PLOS ONE, 11(2), e0148324. doi:10.1371/journal.pone.0148324Lin, B.-S., Lin, B.-S., Chou, N.-K., Chong, F.-C., & Chen, S.-J. (2006). RTWPMS: A Real-Time Wireless Physiological Monitoring System. IEEE Transactions on Information Technology in Biomedicine, 10(4), 647-656. doi:10.1109/titb.2006.874194Hu, S., Wei, H., Chen, Y., & Tan, J. (2012). A Real-Time Cardiac Arrhythmia Classification System with Wearable Sensor Networks. Sensors, 12(9), 12844-12869. doi:10.3390/s120912844Burns, A., Greene, B. R., McGrath, M. J., O’Shea, T. J., Kuris, B., Ayer, S. M., … Cionca, V. (2010). SHIMMER™ – A Wireless Sensor Platform for Noninvasive Biomedical Research. IEEE Sensors Journal, 10(9), 1527-1534. doi:10.1109/jsen.2010.2045498Gil, Y., Wu, W., & Lee, J. (2012). A Synchronous Multi-Body Sensor Platform in a Wireless Body Sensor Network: Design and Implementation. Sensors, 12(8), 10381-10394. doi:10.3390/s120810381Chin-Teng Lin, Kuan-Cheng Chang, Chun-Ling Lin, Chia-Cheng Chiang, Shao-Wei Lu, Shih-Sheng Chang, … Li-Wei Ko. (2010). An Intelligent Telecardiology System Using a Wearable and Wireless ECG to Detect Atrial Fibrillation. IEEE Transactions on Information Technology in Biomedicine, 14(3), 726-733. doi:10.1109/titb.2010.2047401W. Y. Chung, Y. D. Lee, and S. J. Jung, 'A Wireless Sensor Network Compatible Wearable U-Healthcare Monitoring System Using Integrated Ecg, Accelerometer and Spo2', Conf Proc IEEE Eng Med Biol Soc, 2008 (2008), 1529–32.ZigBee Alliance; http://www.zigbee.org/Mahmood, A., Javaid, N., & Razzaq, S. (2015). A review of wireless communications for smart grid. Renewable and Sustainable Energy Reviews, 41, 248-260. doi:10.1016/j.rser.2014.08.036J.S. Lee, Y.W. Su, and C.C. Shen, "A comparative study of wireless protocols: Bluetooth, UWB, ZigBee, and Wi-Fi, 33rd Annual Conference of the IEEE Industrial Electronics Society (IECON), 2007, pp. 46–51.P.P. Parikh, M.G. Kanabar, and T.S. Sidhu, "Opportunities and challenges of wireless communication technologies for smart grid applications, IEEE PES General Meeting, 2010, pp. 1–7.Fadlullah, Z. M., Fouda, M. M., Kato, N., Takeuchi, A., Iwasaki, N., & Nozaki, Y. (2011). Toward intelligent machine-to-machine communications in smart grid. IEEE Communications Magazine, 49(4), 60-65. doi:10.1109/mcom.2011.5741147A.C. Olteanu, G.D. Oprina, N. Tapus, and S. Zeisberg, "Enabling mobile devices for home automation using ZigBee, 19th IEEE International Conference on Control Systems and Computer Science, 2013, pp. 189–195.Shang, Y. (2014). Vulnerability of networks: Fractional percolation on random graphs. Physical Review E, 89(1). doi:10.1103/physreve.89.012813R. Barea-Navarro. Biomedical Instrumentation. Chapter 3. University of Alcala

Relative contributions to vergence eye movements of two binocular cues for motion-in-depth

When we track an object moving in depth, our eyes rotate in opposite directions. This type of "disjunctive" eye movement is called horizontal vergence. The sensory control signals for vergence arise from multiple visual cues, two of which, changing binocular disparity (CD) and inter-ocular velocity differences (IOVD), are specifically binocular. While it is well known that the CD cue triggers horizontal vergence eye movements, the role of the IOVD cue has only recently been explored. To better understand the relative contribution of CD and IOVD cues in driving horizontal vergence, we recorded vergence eye movements from ten observers in response to four types of stimuli that isolated or combined the two cues to motion-in-depth, using stimulus conditions and CD/IOVD stimuli typical of behavioural motion-in-depth experiments. An analysis of the slopes of the vergence traces and the consistency of the directions of vergence and stimulus movements showed that under our conditions IOVD cues provided very little input to vergence mechanisms. The eye movements that did occur coinciding with the presentation of IOVD stimuli were likely not a response to stimulus motion, but a phoria initiated by the absence of a disparity signal

Exploring the Fundamental Dynamics of Error-Based Motor Learning Using a Stationary Predictive-Saccade Task

The maintenance of movement accuracy uses prior performance errors to correct future motor plans; this motor-learning process ensures that movements remain quick and accurate. The control of predictive saccades, in which anticipatory movements are made to future targets before visual stimulus information becomes available, serves as an ideal paradigm to analyze how the motor system utilizes prior errors to drive movements to a desired goal. Predictive saccades constitute a stationary process (the mean and to a rough approximation the variability of the data do not vary over time, unlike a typical motor adaptation paradigm). This enables us to study inter-trial correlations, both on a trial-by-trial basis and across long blocks of trials. Saccade errors are found to be corrected on a trial-by-trial basis in a direction-specific manner (the next saccade made in the same direction will reflect a correction for errors made on the current saccade). Additionally, there is evidence for a second, modulating process that exhibits long memory. That is, performance information, as measured via inter-trial correlations, is strongly retained across a large number of saccades (about 100 trials). Together, this evidence indicates that the dynamics of motor learning exhibit complexities that must be carefully considered, as they cannot be fully described with current state-space (ARMA) modeling efforts

Frequency Characteristics of the Saccadic Eye Movement

Using a piecewise linear approach, individual saccadic eye movements have been Fourier decomposed in an attempt to determine the effect of saccadic amplitude on frequency characteristics. These characteristics were plotted in the traditional Bode plot form, showing gain and phase as a function of frequency for various eye movement amplitudes. Up to about one octave beyond the -3 db gain frequency, the limiting system dynamics represented by the saccadic trajectory of a given amplitude may be considered linear and second order. The -3 db gain frequency was used as a measure of bandwidth, and the -90° phase crossover frequency was used as a measure of undamped natural frequency. These two quantities were used to calculate the damping factor. Both bandwidth and undamped natural frequency decrease with increasing saccadic eye movement amplitude. The damping factor shows no trend with amplitude and indicates approximate critical damping. When compared with the normal variation of characteristics for a given movement, the frequency characteristics of fixed-amplitude saccades showed no generalized trends with changes in direction or DC operating level of movement