Research Topics
 James P KeenerSummaryAffiliation: University of Utah Country: USA Publications
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Publications
 A biophysical model for defibrillation of cardiac tissueJ P Keener
Department of Mathematics, University of Utah, Salt Lake City 84112, USA
Biophys J 71:133545. 1996..To illustrate the usefulness of the model, numerical stimulations are used to show the difference between successful and unsuccessful defibrillation of large pieces of tissue...  Exact reductions of Markovian dynamics for ion channels with a single permissive stateJames P Keener
Department of Mathematics, University of Utah, Salt Lake City, UT, 84112, USA
J Math Biol 60:4739. 2010..Finally, we conclude that solutions of the reduced model are globally asymptotically stable solutions of the full master equation system...  A molecular ruler mechanism for length control of extended protein structures in bacteriaJ P Keener
Department of Mathematics, University of Utah, USA
J Theor Biol 263:4819. 2010..Thus, it is much more likely that interaction will occur when the hook is long than when the hook is short...  How Salmonella Typhimurium measures the length of flagellar filamentsJ P Keener
Department of Mathematics, University of Utah, 155 South 1400 East, Salt Lake City, Utah 84112, USA
Bull Math Biol 68:176178. 2006..The combination of this regulatory network with the lengthdependent rate of growth enable the bacterium to detect length shortening and regrow severed flagellar filaments...  Stochastic calcium oscillationsJames P Keener
Department of Mathematics, University of Utah, Salt Lake City, UT 84112, USA
Math Med Biol 23:125. 2006..By solving this model numerically, information about the timing of wholecell calcium release is obtained. The results of this analysis show a transition to oscillations that agrees well with data and with Monte Carlo simulations...  A model for length control of flagellar hooks of Salmonella typhimuriumJ P Keener
Department of Mathematics, University of Utah, 155 South 1400 East, Salt Lake City, UT 84112, USA
J Theor Biol 234:26375. 2005..We propose that this transition can be detected by the secretant FliK, allowing FliK to interact with FlhB thereby changing the secretion target of the type III secretion machinery and terminating the growth of the hook...  The topology of defibrillationJames P Keener
Department of Mathematics, University of Utah, 155 South 1400 East, Salt Lake City, UT 84112, USA
J Theor Biol 230:45973. 2004..Using topological arguments we draw the general conclusion that with a generic placement of stimulating electrodes, largescale virtual electrodes do not give an adequate explanation for the mechanism of defibrillation...  Model for the onset of fibrillation following coronary artery occlusionJames P Keener
Department of Mathematics, University of Utah, Salt Lake City, UT 84112, USA
J Cardiovasc Electrophysiol 14:122532. 2003..The border zone arrhythmia may drive a "breakup instability" (related to the action potential duration restitution instability) in the surrounding tissue, leading to selfsustained fibrillation...  The effect of spatial scale of resistive inhomogeneity on defibrillation of cardiac tissueJames P Keener
Department of Mathematics, University of Utah, 155 South 1400 East, Salt Lake City, UT 84112, USA
J Theor Biol 223:23348. 2003..With small spatial scale inhomogeneity, there are no similar restrictions...  Diffusion induced oscillatory insulin secretionJ P Keener
Department of Mathematics, University of Utah, Salt Lake City 84112, USA
Bull Math Biol 63:62541. 2001..Bull. Math. Biol., 57(1995), 569591). Furthermore, with reasonable numbers for the experimental parameters and the diffusion of insulin, the model equations do not exhibit oscillations...  The biphasic mystery: why a biphasic shock is more effective than a monophasic shock for defibrillationJ P Keener
Department of Mathematics, University of Utah, Salt Lake City, UT, 84112, USA
J Theor Biol 200:117. 1999..The effect can be seen easily in a model of a single cell and also in a cable model with a ring of excitable cells. Finally, we demonstrate the phenomenon in a twodimensional model of cardiac tissue...  Invariant manifold reductions for Markovian ion channel dynamicsJames P Keener
Department of Mathematics, University of Utah, Salt Lake City, UT 84112, USA
J Math Biol 58:44757. 2009..We also use this to show that the original HodgkinHuxley formulations of potassium channel conductance and sodium channel conductance are the exact solutions of full Markov models for these channels...  Perturbation analysis of spontaneous action potential initiation by stochastic ion channelsJames P Keener
Department of Mathematics, University of Utah, 155 South 1400 East, Salt Lake City, Utah 84112, USA
Phys Rev E Stat Nonlin Soft Matter Phys 84:011918. 2011..We also explore why different diffusion approximation techniques fail to estimate the MFT...  Toward an understanding of fibrin branching structureAaron L Fogelson
Department of Mathematics, University of Utah, 155 South 1400 East, Salt Lake City, Utah 84112, USA
Phys Rev E Stat Nonlin Soft Matter Phys 81:051922. 2010..A higher rate of monomer supply leads to a gel with a higher branch concentration and with shorter fiber segments between branch points. The origin of this dependence is explained...  Influence of the standard free energy on swelling kinetics of gelsJames P Keener
Department of Mathematics, University of Utah, Salt Lake City, Utah 84112, USA
Phys Rev E Stat Nonlin Soft Matter Phys 83:041802. 2011....  Ephaptic coupling in cardiac myocytesJoyce Lin
Department of Mathematics, University of Utah, Salt Lake City, UT 84112, USA
IEEE Trans Biomed Eng 60:57682. 2013....  Modeling electrical activity of myocardial cells incorporating the effects of ephaptic couplingJoyce Lin
Department of Mathematics, University of Utah, Salt Lake City, UT 84112, USA
Proc Natl Acad Sci U S A 107:2093540. 2010..This model can be relatively easily extended to higher dimensions while maintaining numerical efficiency and incorporating ephaptic effects through modeling of complex, irregular cellular geometry...  Ephaptic coupling of cardiac cells through the junctional electric potentialElizabeth D Copene
Department of Mathematics, The University of Utah, Salt Lake City, UT 84112, USA
J Math Biol 57:26584. 2008..We find that there are two distinct types of propagation failure and we are able to characterize parameter space into regions of propagation success and the two different types of propagation failure...  Fibrin gel formation in a shear flowRobert D Guy
Department of Mathematics, University of Utah, 155 South 1400 East, Room 233, Salt Lake City, UT 84112 0090, USA
Math Med Biol 24:11130. 2007..The results show that the thrombin inhibition rate, the gel permeability and the shear rate are key parameters in regulating the height of the fibrin gel...  Facilitation of intracellular H(+) ion mobility by CO(2)/HCO(3)() in rabbit ventricular myocytes is regulated by carbonic anhydraseK W Spitzer
Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
J Physiol 541:15967. 2002..By regulating the carbonic shuttle, CA regulates effective H(+)(i) mobility which, in turn, regulates the spatiotemporal uniformity of pH(i). This is postulated to be a major function of CA in heart...  LowReynoldsnumber swimming in viscous twophase fluidsJian Du
Department of Mathematics, University of Utah, Salt Lake City, Utah 84112, USA
Phys Rev E Stat Nonlin Soft Matter Phys 85:036304. 2012..Our results indicate that both the swimming speed and efficiency may be decreased substantially relative to those for a singlephase fluid...  A mechanomolecular model for the movement of chromosomes during mitosis driven by a minimal kinetochore bicyclic cascadeBlerta Shtylla
Mathematics Department, University of Utah, Salt Lake City, UT, USA
J Theor Biol 263:45570. 2010..Our feedback control model can recreate chromosome movement from prometaphase to anaphase in good agreement with experimental data...  Calsequestrin mediates changes in spontaneous calcium release profilesNessy Tania
Department of Mathematics, University of Utah, 155 S 1400 E Room 233, Salt Lake City, UT 84112, USA
J Theor Biol 265:35976. 2010..Finally, we show that with increased bulk cytoplasmic calcium concentration, the CRU model exhibits deterministic oscillations...  A mathematical model of force generation by flexible kinetochoremicrotubule attachmentsJames P Keener
Department of Mathematics, University of Utah, Salt Lake City, UT 84112
Biophys J 106:9981007. 2014..Based on our model results, we suggest that the underlying principles of biased diffusion paradigm need to be reinterpreted. ..  A mathematical study of volume shifts and ionic concentration changes during ischemia and hypoxiaChung Seon Yi
Department of Mathematics, University of Utah, 155 South 1400 East, 233 JWB, Salt Lake City, Utah 84112, USA
J Theor Biol 220:83106. 2003..The same mechanism is not present in cardiac ion models, and this may explain the qualitative difference in response shown in cardiac tissue...  A mathematical model for quorum sensing in Pseudomonas aeruginosaJ D Dockery
Department of Mathematics, Montana State University, Bozeman, MT 59718, USA
Bull Math Biol 63:95116. 2001..Using this model we show that quorum sensing works because of a biochemical switch between two stable steady solutions, one with low levels of autoinducer and one with high levels of autoinducer...  Phase singularities and termination of spiral wave reentryJames P Keener
J Cardiovasc Electrophysiol 14:5567; author reply 5578. 2003  The role of the biofilm matrix in structural developmentN G Cogan
Mathematics Department, Tulane University, New Orleans, LA 70118, USA
Math Med Biol 21:14766. 2004....  A calciuminduced calcium release mechanism mediated by calsequestrinYoung Seon Lee
Department of Biomedical Sciences, Cornell University, Ithaca, NY 14853, USA
J Theor Biol 253:66879. 2008..Furthermore, this CICR model produces a nonlinear relationship between fractional jSR Ca(2+) release and jSR load. These findings agree with experimental observations in lipid bilayers and cardiac myocytes...