Bradley J Roth

Publications (170) View all

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  Available from: Bradley J Roth

  Conference Proceeding: Simulations of Optical Mapping During Electroporation

  D.L. Janks, B.J. Roth
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  ABSTRACT: Experiments using optical mapping suggest that electroporation occurs in cardiac tissue when the transmembrane potential, V m , is observed to be significantly less than ± 400 mV. Our hypothesis, which we test by numerical simulation, is that V m is greater than ± 400 mV at the tissue surface, but optical mapping underestimates V m because it averages over depth. Results indicate a significant underestimation of V m .
  Engineering in Medicine and Biology Society, 2004. IEMBS '04. 26th Annual International Conference of the IEEE; 10/2004
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  Article: A comparative model of two mechanisms from which a magnetic field arises in the heart

  R A Murdick, B J Roth
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  ABSTRACT: There are two different mechanisms from which a magnetic field can arise in the heart. The first mechanism has the source of the magnetic field as a current dipole oriented perpendicular to the action potential wave front with the ''return'' currents flowing in an adjacent volume conductor. The second mechanism is one with no adjacent volume conductor and has a magnetic field that arises due to the anisotropy of the tissue. We see that the two mechanisms produce magnetic fields of similar magnitudes and similar falloff rates as distance from the tissue increases, indicating that both mechanisms are important. © 2004 American Institute of Physics.
  Journal of Applied Physics 05/2004; 95(9):5116-5122. · 2.17 Impact Factor
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  Article: Magneto-encephalogram artifacts caused by electro-encephalogram electrodes.

  R Murdick, B J Roth
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  ABSTRACT: The electro-encephalogram (EEG) and magneto-encephalogram (MEG) are often measured simultaneously. By Faraday's law of induction, the changing magnetic field of the MEG can induce eddy currents in the EEG electrodes. These eddy currents produce their own magnetic field that adds to that produced by current sources in the brain, resulting in an artifact in the MEG recording. It is shown that, under typical conditions, this artifact is less than 1%, but, during measurements of high temporal frequency and high spatial resolution, the artifact can be as large as 3%.
  Medical & Biological Engineering & Computing 04/2003; 41(2):203-5. · 1.88 Impact Factor
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  Article: Correction to how electrode size affects the electrical potential distribution in cardiac tissue

  B.J. Roth
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  ABSTRACT: First Page of the Article
  IEEE Transactions on Biomedical Engineering 06/2002; · 2.28 Impact Factor
• Conference Proceeding: Averaging over depth during optical mapping of electroporation

  D.L. Janks, B.J. Roth
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  ABSTRACT: During defibrillation, strong electric shocks applied to the heart can cause electroporation: the formation of large, nonselective pores in the cell membrane. Experiments using optical mapping indicate that electroporation occurs in cardiac tissue when the transmembrane potential, V_m, is significantly less than ±400 mV. Our hypothesis, which we test by numerical simulation, is that V_m is greater than ±400 mV at the tissue surface, but optical mapping underestimates V_m because it averages over depth.
  Engineering in Medicine and Biology, 2002. 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society EMBS/BMES Conference, 2002. Proceedings of the Second Joint; 02/2002