The Action Potential in Chara corallina III.* The Hodgkin-Huxley Parameters for the Plasmalemma

1979 ◽  
Vol 6 (3) ◽  
pp. 337 ◽  
Author(s):  
M.J Beilby ◽  
H.G.L Coster
Keyword(s):  
Experimental Data ◽  
Action Potential ◽  
Ionic Currents ◽  
Chara Corallina ◽  
Wide Range ◽  
Time Courses ◽  
Model Equations ◽  
Excitation Processes ◽  
Ionic Components ◽  
Peak Value

An analysis, based on the Hodgkin-Huxley (H-H) equations is given of excitation processes in the plasmalemma of cells of C. corallina. Voltage clamp data for the plasmalemma show the presence of two activation and two inactivation processes and both of these transients are modelled in a manner analagous to the gated Na+ current in squid axons. Separation of the various ionic components of the experimental clamp currents was achieved by fitting the experimental data over a wide range of potentials to the model equations. The potential dependencies of the various H-H parameters for C. corallina, determined from the analysis of experimental results, are presented. A reconstruction is also given of the action potential and it is shown to be in satisfactory agreement with the experimental data. Comparisons are made of the experimental and predicted threshold potential, refractory period and the effects of the external Cl- and Ca�+ ion concentrations on the action potential. From the H-H parameters, the time courses during an action potential of the conductances g*Cl, g*x (� g*Ca?), the non activated/inactivated steady-state conductance g*ss, and the corresponding ionic currents I*Cl, I*x (� I*Ca?) and I*ss are calculated. While in the H-H analysis the peak value of g*x is found to be very large (larger than the peak value of g*Cl), it is shown that nevertheless I*Cl and I*ss dominate during an action potential.

Modeling the Excitability of Mammalian Nerve Fibers: Influence of Afterpotentials on the Recovery Cycle

2002 ◽  
Vol 87 (2) ◽  
pp. 995-1006 ◽  
Author(s):  
Cameron C. McIntyre ◽  
Andrew G. Richardson ◽  
Warren M. Grill
Keyword(s):  
Experimental Data ◽  
Action Potential ◽  
Experimental Studies ◽  
Sensory Nerve ◽  
Nerve Fibers ◽  
Recovery Cycle ◽  
Channel Activation ◽  
Single Action ◽  
Potential Shape ◽  
Wide Range

Human nerve fibers exhibit a distinct pattern of threshold fluctuation following a single action potential known as the recovery cycle. We developed geometrically and electrically accurate models of mammalian motor nerve fibers to gain insight into the biophysical mechanisms that underlie the changes in axonal excitability and regulate the recovery cycle. The models developed in this study incorporated a double cable structure, with explicit representation of the nodes of Ranvier, paranodal, and internodal sections of the axon as well as a finite impedance myelin sheath. These models were able to reproduce a wide range of experimental data on the excitation properties of mammalian myelinated nerve fibers. The combination of an accurate representation of the ion channels at the node (based on experimental studies of human, cat, and rat) and matching the geometry of the paranode, internode, and myelin to measured morphology (necessitating the double cable representation) were needed to match the model behavior to the experimental data. Following an action potential, the models generated both depolarizing (DAP) and hyperpolarizing (AHP) afterpotentials. The model results support the hypothesis that both active (persistent Na+ channel activation) and passive (discharging of the internodal axolemma through the paranodal seal) mechanisms contributed to the DAP, while the AHP was generated solely through active (slow K+ channel activation) mechanisms. The recovery cycle of the fiber was dependent on the DAP and AHP, as well as the time constant of activation and inactivation of the fast Na+ conductance. We propose that experimentally documented differences in the action potential shape, strength-duration relationship, and the recovery cycle of motor and sensory nerve fibers can be attributed to kinetic differences in their nodal Na+ conductances.

scholarly journals A quantitative model for the mechanism of action of the cytochrome c peroxidase of Pseudomonas aeruginosa

1992 ◽  
Vol 283 (3) ◽  
pp. 839-843 ◽  
Author(s):  
N Foote ◽  
R Turner ◽  
T Brittain ◽  
C Greenwood
Keyword(s):  
Experimental Data ◽  
Pseudomonas Aeruginosa ◽  
Cytochrome C ◽  
Close Agreement ◽  
Cytochrome C Peroxidase ◽  
Quantitative Model ◽  
Activation Process ◽  
Stopped Flow ◽  
Wide Range ◽  
Time Courses

Each of the elementary reaction steps in both the activation process and catalytic cycle of the cytochrome c peroxidase of Pseudomonas aeruginosa was characterized using stopped-flow methods. A synthesis of these data led to the establishment of a quantitative model for the action of this enzyme. Comparisons were made between experimental data and calculations over a wide range of enzyme, reductant and H2O2 concentrations. Close agreement was found between empirical and simulated reaction time courses from millisecond to tens of seconds time ranges, giving us confidence in the validity of the quantitative model of this enzyme's actions.

Peristalsis in distal colon of the rabbit: an analysis of mechanical events.

1979 ◽  
Vol 236 (4) ◽  
pp. E464
Author(s):  
M Pescatori ◽  
F Grassetti ◽  
G Ronzoni ◽  
R Mancinelli ◽  
A Bertuzzi ◽  
...  
Keyword(s):  
Experimental Data ◽  
Time Lag ◽  
Circular Muscle ◽  
Quantitative Relationship ◽  
Distal Colon ◽  
Pressure Force ◽  
Circular Layer ◽  
Time Courses ◽  
Model Equations ◽  
Peristaltic Contractions

The mechanical behavior of isolated segments of rabbit distal colon was studied by experimental and theoretical techniques. The isometric isovolumic preparation was adopted to obtain records of endoluminal pressure, force, and wall morphology during 59 spontaneous and 53 electrostimulated peristaltic contractions. On strips of longitudinal and circular muscle, excised from the same segments, the tension-velocity and tension-length relationships were also measured. To describe mechanical events occurring during propulsion, a mathematical model was developed that incorporates the measured characteristics of the muscle. In response to given waveforms for the activation of the two muscular coats, the solution of model equations provides the time courses of pressure, force, and wall morphology. A number of parameters measured in the experimental contractions (e.g., pressure and force peaks, time lag between the stimulus and the peaks, velocity of progression of the peristaltic wave) were compared with model outputs, and a similar pattern of response was found. Therefore the model made it possible to relate segment and strip experimental data and to investigate the temporal and quantitative relationship between the contraction of longitudinal and circular layer.

LIQUIDUS THERMO-BAROMETER FOR THE MODELING OF MAGNETITE — MELT EQUILIBRIUM

2018 ◽  
pp. 71-80
Author(s):  
N. S. Aryaeva ◽  
E. V. Koptev-Dvornikov ◽  
D. A. Bychkov
Keyword(s):  
Experimental Data ◽  
Liquidus Temperature ◽  
Vertical Structure ◽  
Maximum Error ◽  
Silicate Melt ◽  
System Of Equations ◽  
Wide Range ◽  
Basaltic Melts ◽  
Multidimensional Statistics

A system of equations of thermobarometer for magnetite-silicate melt equilibrium was obtained by method of multidimensional statistics of 93 experimental data of a magnetite solubility in basaltic melts. Equations reproduce experimental data in a wide range of basalt compositions, temperatures and pressures with small errors. Verification of thermobarometers showed the maximum error in liquidus temperature reproducing does not exceed ±7 °C. The level of cumulative magnetite appearance in the vertical structure of Tsypringa, Kivakka, Burakovsky intrusions predicted with errors from ±10 to ±50 m.

Modelling of catalyst pellet deactivation

1985 ◽  
Vol 50 (11) ◽  
pp. 2381-2395
Author(s):  
Alena Brunovská ◽  
Ján Buriánek ◽  
Ján Ilavský ◽  
Ján Valtýni
Keyword(s):  
Experimental Data ◽  
Numerical Results ◽  
Benzene Hydrogenation ◽  
Alumina Catalyst ◽  
Temperature Changes ◽  
Catalyst Pellet ◽  
Model Equations ◽  
Catalytic Poison

The diffusion and the shell progressive models of deactivation caused by irreversible chemisorption of a catalytic poison are presented for a single catalyst pellet. The method for solution of the model equations is proposed. The numerical results are compared with experimental data obtained by measuring concentration and temperature changes due to thiophene poisoning in benzene hydrogenation over a nickel-alumina catalyst.

scholarly journals Experimental analysis and ANN prediction on performances of finned oval-tube heat exchanger under different air inlet angles with limited experimental data

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 968-980
Author(s):  
Xueping Du ◽  
Zhijie Chen ◽  
Qi Meng ◽  
Yang Song
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Exchanger ◽  
Correlation Equation ◽  
Tube Heat Exchanger ◽  
Flow Friction ◽  
Air Inlet ◽  
Comparison Results ◽  
Wide Range ◽  
Oval Tube

Abstract A high accuracy of experimental correlations on the heat transfer and flow friction is always expected to calculate the unknown cases according to the limited experimental data from a heat exchanger experiment. However, certain errors will occur during the data processing by the traditional methods to obtain the experimental correlations for the heat transfer and friction. A dimensionless experimental correlation equation including angles is proposed to make the correlation have a wide range of applicability. Then, the artificial neural networks (ANNs) are used to predict the heat transfer and flow friction performances of a finned oval-tube heat exchanger under four different air inlet angles with limited experimental data. The comparison results of ANN prediction with experimental correlations show that the errors from the ANN prediction are smaller than those from the classical correlations. The data of the four air inlet angles fitted separately have higher precisions than those fitted together. It is demonstrated that the ANN approach is more useful than experimental correlations to predict the heat transfer and flow resistance characteristics for unknown cases of heat exchangers. The results can provide theoretical support for the application of the ANN used in the finned oval-tube heat exchanger performance prediction.

scholarly journals Modelling the Inflation and Elastic Instabilities of Rubber-Like Spherical and Cylindrical Shells Using a New Generalised Neo-Hookean Strain Energy Function

2021 ◽  
Author(s):  
Afshin Anssari-Benam ◽  
Andrea Bucchi ◽  
Giuseppe Saccomandi
Keyword(s):  
Experimental Data ◽  
Energy Function ◽  
Limit Point ◽  
Strain Energy ◽  
Cylindrical Shells ◽  
Strain Energy Function ◽  
Model Parameters ◽  
Wide Range ◽  
Cylindrical Tubes ◽  
Gent Model

AbstractThe application of a newly proposed generalised neo-Hookean strain energy function to the inflation of incompressible rubber-like spherical and cylindrical shells is demonstrated in this paper. The pressure ($P$ P ) – inflation ($\lambda $ λ or $v$ v ) relationships are derived and presented for four shells: thin- and thick-walled spherical balloons, and thin- and thick-walled cylindrical tubes. Characteristics of the inflation curves predicted by the model for the four considered shells are analysed and the critical values of the model parameters for exhibiting the limit-point instability are established. The application of the model to extant experimental datasets procured from studies across 19th to 21st century will be demonstrated, showing favourable agreement between the model and the experimental data. The capability of the model to capture the two characteristic instability phenomena in the inflation of rubber-like materials, namely the limit-point and inflation-jump instabilities, will be made evident from both the theoretical analysis and curve-fitting approaches presented in this study. A comparison with the predictions of the Gent model for the considered data is also demonstrated and is shown that our presented model provides improved fits. Given the simplicity of the model, its ability to fit a wide range of experimental data and capture both limit-point and inflation-jump instabilities, we propose the application of our model to the inflation of rubber-like materials.

Linear transformations extract parameters of ionic currents and action potential features from pseudo-ECG in cardiomyocyte models

2020 ◽  
Author(s):  
Salim Baigildin ◽  
Konstantin Ushenin ◽  
Aigul Fabarisova ◽  
Marat Bogdanov ◽  
Olga Solovyeva
Keyword(s):  
Action Potential ◽  
Ionic Currents ◽  
Linear Transformations
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