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Cortical magnetic and electric fields associated with voluntary finger movements

Brain Topography 1994年第3期6卷 175-183页

作者： Nagamine, Takatshi Toro, Camilo Balish, Marshall Deuschr, Günther Wang, Binseng Sato, Susumu Shibasaki, Hiroshi Hallett, Mark Department of Brain Pathophysiology Kyoto University School of Medicine Kyoto 606 Sakyo-ku Japan Human Motor Control Section Medical Neurology Branch National Institute of Neurological Disorders and Stroke National Institutes of Health Bethesda MD United States Neurophysiology Unit Epilepsy Research Branch National Institute of Neurological Disorders and Stroke National Institutes of Health Bethesda MD United States Biomedical Engineering and Instrumentation Program National Center for Research Resources National Institutes of Health Bethesda MD United States State University of Campinas Campinas SP 13081 Brazil

Multichannel recordings of both movement-related magnetic fields (MRMFs) and movement-related cortical potentials (MRCPs) were simultaneously recorded in association with voluntary unilateral self-paced index finger abduction movement in two normal volunteers. 1) Slow magnetic field (readiness field;RF) can be detected several hundred msec before the movement onset, and its field distribution indicates the existence of the largest generator source over the contralateral primary motor area. Taken together with the vertex-maximal Bereitschaftspotential which corresponds to the earlier part of the RF, the complexity of this magnetic field suggested by relatively low correlation value in single dipole model indicates the co-activation of other underlying generators besides this largest dipole. 2) The utilization of MRMF with MRCP facilitates the separation of two distinct electrophysiological events in proximity to the movement onset, which are difficult to be determined by the technique of MRCP only. Those are the motor field (MF) and the movement evoked field I (MEFI) in MRMF, and the parietal peak motor potential (ppMP) and the frontal peak motor potential (fpMP) in MRCP, which occur approximately 20 and 100 msec after EMG onset, respectively. These two subcomponents may imply the culmination of motor cortex and sensory feedback activation, respectively. Combined study of MRMF and MRCP will provide better definition of cortical events related to voluntary movement than the study of either modality alone. © 1994 Human Sciences Press, Inc.

关键词： Magnetoencephalography Motor field Movement evoked field Movement-related cortical potential Movement-related magnetic field Readiness field

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Molecular Consequences of Cardiac Valve Development as a Result of Altered Hemodynamics

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Microscopy and Microanalysis 2017年第S1期23卷 1330-1331页

作者： Vinal Menon Lorain Junor John Eberth Stephanie Ford Matt McPheeters Michael Jenkins Marwa Belhaj Jay Potts Department of Cell Biology and Anatomy University of South Carolina School of Medicine Columbia USA. Instrumentation Resource Facility University of South Carolina School of Medicine Columbia USA. Biomedical Engineering Program College of Engineering and Computing University of South Carolina Columbia USA. Division of Neonatology University Hospitals Rainbow Babies and Children's Hospital Cleveland USA. Department of Biomedical Engineering Case Western Reserve University Cleveland USA. Department of Pediatrics Case Western Reserve University Cleveland USA.

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Analysis of functional magnetic resonance images by wavelet decomposition

Analysis of functional magnetic resonance images by wavelet ...

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IEEE International Conference on Image Processing

作者： U.E. Ruttimann N.F. Ramsey D.W. Hommer P. Thevenaz Chulhee Lee M. Unser Sect. on Brain Electrophysiol. & Imaging Nat. Inst. of Health Bethesda MD USA Section on Brain Electrophysiology and Imaging National Institute on Alcohol Abuse and Alcoholism Bethesda MD USA Biomedical Engineering and Instrumentation Program National Institutes of Health Bethesda MD USA

The use of the wavelet transform to detect differences between sequentially acquired functional magnetic resonance images (fMRIs) is explored. A statistical data model is developed that makes use of the orthogonality and regularity conditions of the wavelets to achieve a signal decomposition into uncorrelated components, enabling application of standard parametric tests of significance on wavelet coefficients directly. This overcomes the problems associated with high intervoxel correlations in the spatial domain, and achieves economy in statistical testing by limiting the search for significant signal components to a subspace where the signal power is located. Thus, a smaller p-value adjustment for multiple testing is required, resulting in a lower detection threshold for a given overall level of statistical significance. For the fMRIs investigated, a 10:1 reduction in the number of statistical tests was achieved, and about 1% of the wavelet coefficients were significant (p<0.05 per volume), which then served to resynthesize the difference images by inverse wavelet transform.

关键词： Image analysis Magnetic analysis Magnetic resonance Wavelet analysis Testing Wavelet transforms Wavelet coefficients Data models Signal resolution Standards development

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Positive Staining for Improved Contrast Of Macromolecules In Transmission Electron Microscopy

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Microscopy and Microanalysis 2018年第S1期24卷 1730-1731页

作者： Kelly A. Parker Yue Li Adam Eshein Shengshuang Zhu Cheri M. Hampton Lawrence F. Drummy Vinayak P. Dravid Department of Materials Science & Engineering Northwestern University Evanston Illinois60208 Applied Physics Program Northwestern University Evanston Illinois 60208 Department of Biomedical Engineering Northwestern University Evanston Illinois60208 Materials and Manufacturing Directorate Air Force Research Laboratory WPAFB OH45433 Electron Probe Instrumentation Center (EPIC) Facility NUANCE Center Northwestern University Evanston Illinois60208

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PID control design and implementation for laboratory scale infant incubator temperature using FOPDT model

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AIP Conference Proceedings 2020年第1期2314卷

作者： Akif Rahmatillah Inten Fauziah Hidayat Alfian Pramudita Putra Osmalina Nur Rahma Suhariningsih 1Medical Instrumentation Laboratory Biomedical Engineering Study Program Faculty of Science & Technology Universitas Airlangga Surabaya Indonesia 2Institute of Tropical Disease (ITD) Universitas Airlangga Surabaya Indonesia

Premature babies have difficulty for regulating their body temperature because weight deficiency. Infant incubator that equipped by temperature control system can support thermoregulation process in baby body. This paper explained design of temperature control system using Proportional-Integral-Derivative (PID) controller and its implementation to the laboratory scale infant incubator. The transfer function of infant incubator was obtained by step test method using First-Order and Dead Time (FOPDT) model where process gain K = 0.29, settling time Ts = 18s and dead time Td = 1. Ziegler-Nichols (ZN) and Direct Synthesis (DS) PID coefficients tuning method was used is this experiment and it resulted for ZN tunning method, proportional gain Kc = 20.14, integration time Ti = 0.2 and derivative time Td = 0.05 and DS tunning method proportional gain Kc = 5, integration time Ti = 18. PID controller was implemented to the Personal Computer (PC) with LabVIEW 2013 programing language, LabJack U3 HV data acquisition device and LM-35 temperature sensor. Set point of temperature that required was 350C with t and 250C initial temperature. The controller performance that resulted by this experiment were for ZN tunning method 38 minutes for settling time while DS tunning method resulted 12 minutes for setling time.

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Design and implementation of multichannel EMG for upper extremity myoelectric signal acquisition using IIR filter

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AIP Conference Proceedings 2020年第1期2314卷

作者： Akif Rahmatillah Amila Sofiah Prihartini Widiyanti 1Medical Instrumentation Laboratory Biomedical Engineering Study Program Faculty of Science & Technology Universitas Airlangga Surabaya Indonesia 2Institute of Tropical Disease (ITD) Universitas Airlangga Surabaya Indonesia

This study aimed at designing and implementing a multichannel EMG based on Infinite Impulse Response (IIR) filter and then compare its performance with the standard EMG devices. Hence, the design of this multichannel EMG system consists of two parts: hardware and software. The hardware comprises instrumentation amplifier and NI DAQ USB 6009 as data acquisition device, while the software is composed of myoelectric signal processing (e.g. filtering, rectifying, and smoothing) and interface signal on personal computer (PC) using LabVIEW programming. To test the device, two procedures were performed, there were instrumentation test and performance test of the EMG device. The instrumentation test resulted in the gain value of instrumentation amplifier at 12.794 times with linearity of 0.9998. Moreover, the response of implemented Butterworth IIR filter is compatible with the design at the cut off frequency of 30-400 Hz and 50 Hz. For the performance test, quantitative and qualitative data recorded from normal male subjects aged of 20-40 were compared. The result showed that EMG prototype work as well as EMG comparison with relative error percentage for each value parameter of maximum, minimum, and average amplitude signals at 14.05885 %, 14.82683 %, and 14.0411 % respectively. Furthermore, the features of recorded signal for similar simultaneous movements using EMG prototype also share identical features with the recorded signal using standard EMG.

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Finite‐amplitude propagation in lossless and absorptive media

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The Journal of the Acoustical Society of America 2005年第S1期84卷 S9-S9页

作者： Clarence R. Reilly Kevin J. Parker Department of Electrical Engineering University of Rochester Rochester NY 14627 Medical Instrumentation Program Indianapolis Center for Advanced Research Inc. Indianapolis IN 46204 Rochester Center for Biomedical Ultrasound University of Rochester Rochester NY 14627

The propagation of finite‐amplitude waves in distilled water and an absorptive fluid media with acoustic characteristics similar to tissue was investigated. Axial and focal beampatterns of linear and quasilinear waves were obtained from lens focused sources of 1.75, 2.25, 2.94, and 3.38 MHz using a PYDF needle‐type hydrophone. Experimental beampatterns were compared to spherically converging and focused Gaussian beam theories. The shock parameter at the focus predicted from Gaussian theory was in general agreement with the estimate made from the relative strengths of the first four harmonics to the fundamental. Apodization provided by the lens reduced, but did not eliminate, the nearfield maxima, minima, and sidelobes associated with a piston source. Additional sidelobes predicted from the Khokhlov‐Zabolotskaya‐Kuznetsov (KZK) equation were evident in the harmonic beampatterns. Harmonic focal beamwidths decreased as n−1/2 for the lower source frequencies, in agreement with theory. Beamwidths were generally more narrow in the absorptive media than in the water. The second harmonic peak location on‐axis was distal to the fundamental, although the difference was small for higher source frequencies and propagation in the absorptive media. Higher harmonics had sharper axial focal dimensions, but the position of the axial peak was dependent on the trade‐off between propagation growth and decay caused by attenuation. The extension of the results to propagation in tissue is noted.

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Microcalorimetric studies of metabolic processes in parasitic protozoa

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Parasitology International 1998年 47卷 223-223页

作者： JA Dvorak CP Mudd Laboratory of Parasitic Diseases National Institute of Allergy & Infectious Diseases National Institutes of Health Bethesda MD 20892-0425 U.S.A. Biomedical Engineering and Instrumentation Program Division of Research Services NIH U.S.A.

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From Challenges and Pitfalls to Recommendations and Opportunities: Implementing Federated Learning in Healthcare

arXiv

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arXiv 2024年

作者： Li, Ming Xu, Pengcheng Hu, Junjie Tang, Zeyu Yang, Guang Bioengineering Department Imperial-X Imperial College London LondonW12 7SL United Kingdom National Heart and Lung Institute Imperial College London LondonSW7 2AZ United Kingdom Athinoula A. Martinos Center for Biomedical Imaging Massachusetts General Hospital BostonMA United States State Key Laboratory of Extreme Photonics and Instrumentation College of Optical Science and Engineering Zhejiang University Hangzhou China Tri-Institutional Computational Biology & Medicine Program Weill Cornell Medicine of Cornell University New York United States Cardiovascular Research Centre Royal Brompton Hospital LondonSW3 6NP United Kingdom School of Biomedical Engineering & Imaging Sciences King’s College London LondonWC2R 2LS United Kingdom

Federated learning holds great potential for enabling large-scale healthcare research and collaboration across multiple centres while ensuring data privacy and security are not compromised. Although numerous recent studies suggest or utilize federated learning based methods in healthcare, it remains unclear which ones have potential clinical utility. This review paper considers and analyzes the most recent studies up to May 2024 that describe federated learning based methods in healthcare. After a thorough review, we find that the vast majority are not appropriate for clinical use due to their methodological flaws and/or underlying biases which include but are not limited to privacy concerns, generalization issues, and communication costs. As a result, the effectiveness of federated learning in healthcare is significantly compromised. To overcome these challenges, we provide recommendations and promising opportunities that might be implemented to resolve these problems and improve the quality of model development in federated learning with healthcare. © 2024, CC BY-NC-ND.

关键词： Federated learning

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Highly accelerated EPI with wave encoding and multi-shot simultaneous multi-slice imaging

arXiv

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arXiv 2021年

作者： Cho, Jaejin Liao, Congyu Tian, Qiyuan Zhang, Zijing Xu, Jinmin Lo, Wei-Ching Poser, Benedikt A. Stenger, V. Andrew Stockmann, Jason Setsompop, Kawin Bilgic, Berkin Athinoula A. Martinos Center for Biomedical Imaging Massachusetts General Hospital BostonMA United States Harvard Medical School BostonMA United States Radiological Sciences Laboratory Stanford University Palo AltoCA United States State Key Laboratory of Modern Optical Instrumentation College of Optical Science and Engineering Zhejiang University Hangzhou China Siemens Medical Solutions BostonMA United States Maastricht Brain Imaging Centre Maastricht University Maastricht Netherlands MR Research Program Department of Medicine John A. Burns School of Medicine University of Hawai'i HI United States Harvard-MIT Health Sciences and Technology Massachusetts Institute of Technology CambridgeMA United States

Purpose: To introduce wave encoded acquisition and reconstruction techniques for highly accelerated echo planar imaging (EPI) with reduced g-factor penalty and image artifacts. Method: Wave-EPI involves playing sinusoidal gradients during the EPI readout while employing interslice shifts as in blipped-CAIPI acquisitions. This spreads the aliasing in all spatial directions, thereby taking better advantage of 3D coil sensitivity profiles. The amount of voxel spreading that can be achieved by the wave gradients during the short EPI readout period is constrained by the slew rate of the gradient coils and peripheral nerve stimulation (PNS) monitor. We propose to use a "half-cycle" sinusoidal gradient to increase the amount of voxel spreading that can be achieved while respecting the slew and stimulation constraints. Extending wave-EPI to multi-shot acquisition minimizes geometric distortion and voxel blurring at high in-plane resolution, while structured low-rank regularization mitigates shot-to-shot phase variations without additional navigators. We propose to use different point spread functions (PSFs) for the k-space lines with positive and negative polarities, which are calibrated with a FLEET-based reference scan and allow for addressing gradient imperfections. Results: Wave-EPI provided whole-brain single-shot gradient echo (GE) and multi-shot spin echo (SE) EPI acquisitions at high acceleration factors and was combined with g-Slider slab encoding to boost the SNR level in 1mm isotropic diffusion imaging. Relative to blipped-CAIPI, wave-EPI reduced average and maximum g-factors by up to 1.21- and 1.37-fold, respectively. Conclusion: Wave-EPI allows highly accelerated single- and multi-shot EPI with reduced g-factor and artifacts and may facilitate clinical and neuroscientific applications of EPI by improving the spatial and temporal resolution in functional and diffusion imaging. Copyright © 2021, The Authors. All rights reserved.

关键词： Signal encoding

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