Mg2+-dependent electrical control of flagellar activity in Euglena

1977 ◽  
Vol 23 (1) ◽  
pp. 211-225
Author(s):  
K.M. Nichols ◽  
R. Rikmenspoel
Keyword(s):  
High Speed ◽  
External Medium ◽  
Average Frequency ◽  
Current Injection ◽  
Initial Activity ◽  
Free Medium ◽  
Electrical Control ◽  
Negative Current ◽  
Smooth Dependence ◽  
Injection Cycle

When a Euglena gracilis in a Ca2+-containing medium is impaled with a microelectrode, the flagellum is instantly ejected. In a Ca2+-free medium to which 1 mM EGTA has been added, the flagellum remains attached to the organism, but it loses activity upon impalement. Externally added ATP at a concentration of 10 mM will sustain normal flagellar activity (at approximately 20 Hz) of an impaled Euglena. If negative direct current of several tenths of a microamp is injected through the impaling microelectrode, the flagellar activity is stopped or much reduced. When the current injection is turned off the flagellum returns to its initial activity. This cycle can be repeated many times on the same animal, independent of whether Mg2+ is present in the external medium or not. If 1 micrometer of gramicidin is added to Ca2+-free medium containing 1 mM EGTA and 10 mM ATP, the flagellar activity becomes dependent on external Mg2+. Without external Mg2+ no flagellar activity is present after one or two current injection cycles as described above. With 1 mM Mg2+ present in the external medium many cycles (up to 10) can be produced. This Mg2+-dependent flagellar activity shows a smooth dependence on the amount of current injected. Observations taken by high speed cinemicrography show that in the third injection cycle the average frequency of the flagellar motion is 16-3 Hz at 0 muA, is 8 Hz at 0-2 muA, and is approximately 0 at 0-6 muA of negative current. The injection of positive current results in an increase in flagellar frequency dependent on the amount of current injected. The data indicate that the control of motility of Euglena flagella is dependent on an electrically activated Mg2+ pump.

Electrical control of flagellar activity in impaled bull spermatozoa

1979 ◽  
Vol 35 (1) ◽  
pp. 123-138
Author(s):  
P.M. O'Day ◽  
R. Rikmenspoel
Keyword(s):  
Cell Membrane ◽  
Direct Current ◽  
Transport Process ◽  
Current Injection ◽  
Magnesium Concentration ◽  
Electrical Control ◽  
Transmembrane Potentials ◽  
Negative Current ◽  
Bull Spermatozoon ◽  
Active Transport Process

The control of bull spermatozoon flagellar activity has been investigated using direct current injection into the cells through an impaling glass microelectrode. Negative current injection results in a decrease in the flagellar frequency. Flagellar frequencies can be decreased to zero with high negative currents. This current injection response is dependent on the magnesium concentration available to the spermatozoon interior. The current injection response is nearly independent of ATP concentrations. Resistance measurements indicate that the current injection pathway has a resistance of about 200 +/− 300 k omega, and that the current flowing through the cell membrane is not exceedingly large. Measurements of the induced potentials indicate transmembrane potentials during current injection of about −35 +/− 30 mV per microA of injected current. The results are compatible with an active transport process in bull spermatozoa that controls the flagellar activity in response to current injection by decreasing the internal Mg2+ concentrations during the injection of current.

Multi-Objective Topological Optimization of Support Frame for High-Speed and Heavy-Load Triangle Track Wheel Based on Analytic Hierarchy Process

2018 ◽  
Author(s):  
Fenghe Wu ◽  
Zhaohua Wang ◽  
Yinxu Sun ◽  
Yulin Yang ◽  
Yongxin Li ◽  
...  
Keyword(s):  
Topology Optimization ◽  
High Speed ◽  
Working Condition ◽  
Average Frequency ◽  
Frequency Method ◽  
Analytic Hierarchy ◽  
Heavy Load ◽  
Multi Objective ◽  
Support Frame ◽  
Hierarchy Process

The high-speed, heavy-load and changeable triangle track wheel is a motion device that can carry out interchange between the track wheel and tire in an ordinary vehicle. The topology optimization for the support frame can reduce weight and improve the maneuverability of the vehicle. However, it is difficult to consider simultaneously its weight, stiffness and modal in the process of the structure optimization. Thus, a topology optimization method for multi-objective and multi-working-condition is proposed based on the AHP (analytic hierarchy process) and average frequency method. Firstly, considering the static multi-stiffness target and dynamic vibration frequency target, using the compromise programming method and average frequency method, the objective function of the multi-objective and multi-working-condition topology optimization is established. Then, based on the optimization target, design criteria and indexes, the lightweight hierarchical structure model of the support frame consisting of three levels and eight weight factors is established. Values of 8 weight coefficients of the multi-objective topology optimization are determined through solving the weight factor judgment matrix. Finally, considering the multi-working-condition, taking the minimum objective function of the static and dynamic characteristics as target, and the volume ratio is 50% as boundary, the mathematical model of the topology optimization is established. Simulation results show that the stiffness and strength of the support frame are improved respectively by 74.3% and 1.3% while its weight is reduced by 16.3%. This method also provides a new way to the lightweight design for other large, heavy and multi-condition equipment.

Rhythmic hyperpolarizations and depolarization of sympathetic ganglion cells induced by caffeine

1976 ◽  
Vol 39 (3) ◽  
pp. 547-563 ◽  
Author(s):  
K. Kuba ◽  
S. Nishi
Keyword(s):  
Action Potential ◽  
Sympathetic Ganglion ◽  
External Medium ◽  
Ganglion Cells ◽  
Membrane Resistance ◽  
Free Medium ◽  
Dibutyryl Cyclic Amp ◽  
High K ◽  
Hyperpolarizing Response ◽  
K Permeability

Superfusion of the isolated sympathetic ganglion of the bullfrog with a caffeine-containing (1-6 mM) solution caused in many cells an initial slow hyperpolarization which was followed by a subliminal depolarization interruped by rhythmic hyperpolarizations. A hyperpolarization, similar to one of the rhythmic hyperpolarizations, could be triggered by an action potential in the presence of caffeine. The action potential itself was not markedly affected by caffeine except for its afterhyperpolarization which was prolonged. All these caffeine-induced hyperpolarizations were associated with a marked reduction of the membrane resistance, their amplitude was increased in a K+-free solution and decreased in a high-K+ solution, and their polarity was reversed at the same level at which the afterhyperpolarization was also inverted. This reversal level was not altered by omission of Na+ or C1- from the external medium. These hyperpolarizations were reversibly abolished by depletion of external Ca2+ or replacement of external Ca2+ by Mg2+. Excess of external Ca2+ caused a shortening of the interval between rhythmic hyperpolarizations. Furthermore, iontophoretic injection of EDTA into the cytoplasm markedly depressed the initial caffeine hyperpolarizatin and abolished both the rhythmic and evoked caffeine hyperpolarizations. The caffeine-induced depolarization was not affected by omission of external Cl-. It was decreased in a Na+-free medium, but completely eliminated by omission of both Na+ and Ca2+ from the external medium. Tetrodotoxin did not impair the production of the initial and the rhythmic hyperpolarizations. A strong depolarizing pulse could evoke a typical hyperpolarizing response in the presence of this compound. Dibutyryl cyclic AMP, d-tubocurarine, atropine, and phenoxybenzamine were without effect on the caffeine-induced hyperpolarizations and depolarization. It was concluded that each caffeine-induced hyperpolarization is the result of an increased K+ permeability, which is probably caused by a rise in the internal Ca2+ concentration. It was also concluded that the caffeine-induced depolarization is due to an increased membrane permeability to Ca2+ and Na+.

scholarly journals Advanced Control Method of 5-Phase Dual Concentrated Winding PMSM for Inverter Integrated In-Wheel Motor

2021 ◽  
Vol 12 (2) ◽  
pp. 61
Author(s):  
Kan Akatsu ◽  
Keita Fukuda
Keyword(s):  
High Speed ◽  
Control Method ◽  
Permanent Magnet Synchronous Motor ◽  
Torque Ripple ◽  
Current Injection ◽  
Control Methods ◽  
High Current ◽  
Advanced Control ◽  
Speed Mode ◽  
Current Ripple

This paper presents some techniques for driving novel 5 phase dual winding PMSM (Permanent Magnet Synchronous Motor) for the in-wheel motor. The motor realizes winding change over characteristics that can expand driving area from high-torque mode to high-speed mode due to the dual winding construction. However, the dual winding structure makes a high-current ripple due to high coupling between windings. The paper proposes some control methods to reduce the current ripple, including inverter career ripple. The paper also presents harmonics current injection, such as the 3rd harmonics current injection method, to reduce the torque ripple and generate higher torque.

Parametric Study of the Frequency of Bubble Formation at a Single Orifice With Liquid Cross-Flow

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Miguel A. Balzan ◽  
Franz Hernandez ◽  
Carlos F. Lange ◽  
Brian A. Fleck
Keyword(s):  
Mass Flow ◽  
High Speed ◽  
Liquid Velocity ◽  
Bubble Formation ◽  
Cross Flow ◽  
Average Frequency ◽  
Jet Breakup ◽  
Mass Flow Rates ◽  
Experimental Values ◽  
Processing Techniques

The bubble formation frequency from a single-orifice nozzle subjected to the effects of a crossflowing liquid was investigated using high-speed shadowgraphy, combined with image analysis and signal processing techniques. The effects of the nozzle dimensions, orientation within the conduit, liquid cross-flow velocity, and gas mass flow rate were evaluated. Water and air were the working fluids. Existing expressions in the literature were compared to the experimental values obtained. The expressions showed modest agreement with the experimental mean average frequency magnitude. It was found that increasing the gas injection diameter could decrease the bubbling frequency approximately 12% until reaching a certain value (0.52 mm). Further increasing the nozzle dimensions increase the frequency by around 20%. Bubbling frequency is more sensitive to the liquid velocity where changes up to 63% occurred when the velocity was raised from 3.1 to 4.3 m/s. Increasing gas mass flow rates decreased the gas jet breakup frequency in all cases. This phenomenon was primarily attributed to changes in the bubbling mode from discrete bubbling to pulsating and jetting modes. The nozzle orientation plays a role in modifying the bubbling frequency, having a higher magnitude when oriented against gravity.

Synaptic Drive to Motoneurons During Fictive Swimming in the Developing Zebrafish

2001 ◽  
Vol 86 (1) ◽  
pp. 197-210 ◽  
Author(s):  
Robert R. Buss ◽  
Pierre Drapeau
Keyword(s):  
High Speed ◽  
Activity Patterns ◽  
Average Frequency ◽  
Synaptic Activity ◽  
Glutamate Antagonists ◽  
Correlated Activity ◽  
Cell Current ◽  
Burst Swimming ◽  
Tonic Pattern ◽  
Synaptic Drive

The development of swimming behavior and the correlated activity patterns recorded in motoneurons during fictive swimming in paralyzed zebrafish larvae were examined and compared. Larvae were studied from when they hatch (after 2 days) and are first capable of locomotion to when they are active swimmers capable of capturing prey (after 4 days). High-speed (500 Hz) video imaging was used to make a basic behavioral characterization of swimming. At hatching and up to day 3, the larvae swam infrequently and in an undirected fashion. They displayed sustained bursts of contractions (‘burst swimming’) at an average frequency of 60–70 Hz that lasted from several seconds to a minute in duration. By day 4 the swimming had matured to a more frequent and less erratic “beat-and-glide” mode, with slower (∼35 Hz) beats of contractions for ∼200 ms alternating with glides that were twice as long, lasting from just a few cycles to several minutes overall. In whole cell current-clamp recordings, motoneurons displayed similar excitatory synaptic activity and firing patterns, corresponding to either fictive burst swimming (day 2–3) or beat-and-glide swimming (day 4). The resting potentials were similar at all stages (about −70 mV) and the motoneurons were depolarized (to about −40 mV) with generally non-overshooting action potentials during fictive swimming. The frequency of sustained inputs during fictive burst swimming and of repetitive inputs during fictive beat-and glide swimming corresponded to the behavioral contraction patterns. Fictive swimming activity patterns were eliminated by application of glutamate antagonists (kynurenic acid or 6-cyano-7-nitroquinoxalene-2,3-dione anddl-2-amino-5-phosphonovaleric acid) and were modified but maintained in the presence of the glycinergic antagonist strychnine. The corresponding synaptic currents underlying the synaptic drive to motoneurons during fictive swimming could be isolated under voltage clamp and consisted of cationic [glutamatergic postsynaptic currents (PSCs)] and anionic inputs (glycinergic PSCs). Either sustained or interrupted patterns of PSCs were observed during fictive burst or beat-and-glide swimming, respectively. During beat-and-glide swimming, a tonic inward current and rhythmic glutamatergic PSCs (∼35 Hz) were observed. In contrast, bursts of glycinergic PSCs occurred at a higher frequency, resulting in a more tonic pattern with little evidence for synchronized activity. We conclude that a rhythmic glutamatergic synaptic drive underlies swimming and that a tonic, shunting glycinergic input acts to more closely match the membrane time constant to the fast synaptic drive.

High-speed electrical control of a solid-state photonic quantum interface

2011 ◽  
Author(s):  
Antoine Boyer de la Giroday ◽  
Anthony J. Bennett ◽  
Matthew A. Pooley ◽  
Mark Stevenson ◽  
Niklas Skold ◽  
...  
Keyword(s):  
Solid State ◽  
High Speed ◽  
Electrical Control ◽  
Quantum Interface
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