Pulse control

Figure 7. Slow inactivation of Na channels is potentiated by STX. The graph shows the time required for the recovery of Na channels to an activatable state after a long (1 sec, +50 mV) inactivating depolarization. When tested by a brief test pulse, control currents (A) recovered in a fast (r = 233 msec) phase. Addition of STX (q, 2 nM, which approximately halved the currents with no inactivating pulse) approximately doubled the fraction of currents recovering in the slow phase and also increased the time constant of slow recovery. The fast recovery rate was unaffected. (Reproduced with permission from Ref. 47. Copyright 1986 The New York Academy of Sciences).

S. Makarychev-Mikhailov, A. Shvarev, and E. Bakker, Pulstrodes triple pulse control of potentiometric sensors. J. Am, Chem, Soc. 126, 10548—10549 (2004). 

B. Kohler I would like to make a comment about the experimental status of shaped pulse control. A series of experiments have been performed in Prof. Kent Wilson s laboratory that directly validate the use of tailored light fields for controlling molecular quantum dynamics. 

Block and co-workers [35] modified the atom probe to develop a method called pulsed-field desorption mass spectrometry (PFDMS), whereby a short high-voltage pulse desorbs all species present on the tip during a catalytic reaction. The repetition frequency of the field pulse controls the time for which the reaction is allowed to proceed. Hence, by varying the repetition frequency between desorption pulses in a systematic way, one can study the kinetics of a surface reaction [35], In fact, this type of experiment - where one focuses on a facet of desired structure, which may include steps and defects - comes close to one of the fundamental goals of catalyst characterization, namely studying a catalytic reaction on substrates of atomically resolved structure with high time resolution. 

Fig. 7.11. Four excitation-pulse waveforms achieving the highest ion yield ratio of ni29/m3i. Waveforms in a and b were obtained by the self-learning adaptive pulse control. The waveform in c was obtained by applying a linear frequency chirp at 2.2 x 10 2 ps2 by the 4/-pulse shaper. The waveform in d was obtained by applying a linear frequency chirp at 2.2 x 10 2 ps2 by adjusting the pulse compressor...

For electroporation ELECTROMAX DH10B competent cells with pUC119 control plasmid (Gibco-BRL). We use Gene Pulser (Bio-Rad, Richmond, CA) equipped with Pulse Controller and E. coli Pulser cuvet with 0.1-cm gap (Bio-Rad) for electroporation of E. coli. 

Koehl RM, Adachi S, Nelson KA. Multiple-pulse control and bispectral 2D Raman analysis of nonlinear lattice dynamics. In Ultrafast Phenomena XI. T Elsaesser et al., eds. Berlin Springer-Verlag, 1998 136-137. 

A discernible trend in modem pump design is towards the use of very small pistons (stroke volume around 100 pi). These tiny pistons have to be operated at very high driving speeds, to provide the flow rates required in analytical HPLC. However, when they are used in combination with electronic feedback pulse control mechanisms, as described above, they can provide extremely stable solvent delivery characteristics. Such is the efficacy of this approach that single piston pumps designed in this way are able to easily out-perform older dual piston pumps, and are consequently beginning to account for a major part of the LC pump market. 

This chapter reports experimental and analytical results for pulsed control of combustion instabilities at both fundamental and subharmonic frequencies. Two suites of control algorithms have been developed one based on least-mean-square (LMS) techniques that is suitable for inner-loop stabilization of combustion instabilities, and one bcised on direct optimization that can be used either for stabilization or outer-loop optimization of combustion process objectives, such as flame compactness or emissions. 

This formula was verified in the tube combustor by experimentally determining the ultimate gain of a linear phase-shift controller to be 4.2 and then using a pulsed controller with the same phase shift and various pulse heights. By observing the amplitude of the ultimate limit cycle, the ultimate gain iuit can be computed at each pulse height. The plot in Fig. 18.2 shows that this computation yields the expected value of 4.2. 

Figure 18.4 Results of pulsed control of a tube combustor using the LMS algorithm with two different height pulses ( = 0.6) 1 — proportional 2 — H = 0.1 3 — H = 0.2 and 4 — uncontrolled.

Carson, J.M. 2001. Subharmonic and non-subharmonic pulsed control of thermoacoustic instabilities Analysis and experiment. M.S. Thesis. Blacksburg, VA Virginia Polytechnic Institute and State University. 

Baumann, W. T., W. R. Saunders, and J. M. Carson. 2005 (in press). Pulsed control of thermo-acoustic instabilities Analysis and experiment. ASME Transactions on Dynamic Systems, Measurement and Control. 

A second laser is required to produce fhe Stokes photons for the CARS interaction. This can be achieved with a separate Stokes laser with its own pulse control system or, as is shown in Figure 13.8, some of the laser energy from the pump laser can be used to optically pump a laser suited to the CARS system. The symchro-nization of the timing between the pump and Stokes laser systems must be accurate to within 1 ms to ensure that the two laser beams arrive at the same place at the same time. The advantage of fhe latter laser system is that only one timing circuit is needed to keep the pump... 

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