Input signals

Sample times for the microprocessor-based SLCs vaiy from O.I to 0.4 seconds. Low-pass analog electronic filters are installed on the process inputs to stop abasing errors caused by fast changes in the process signal. Input filter time constants are typically in the range From O.I to I s. Microprocessor-based SLCs may be made part of a DCS by using the communication port (RS-488 is common) on the controller or may be operated in a standalone mode independent of the DCS. 

A broad variety of diseases may cause neuropathic pain 935 Injured axons may develop spontaneous and repetitive firing known as ectopic activity 935 Sensory neurons transform their phenotype 936 Spinal disinhibition allows more nociceptive signal input 936 Peripheral nerve injury provokes a marked neuroimmune reaction 937... 

Spinal disinhibition allows more nociceptive signal input. Following peripheral nerve injury there is a reduction in the GABAergic component of postsynaptic inhibitory currents caused by a degeneration of GABAergic interneurons [24] (Fig. 57-6). This loss of inhibition (disinhibition) results in an overall increase in the excitability of dorsal horn neurons. The degeneration of inhibitory interneurons is due to an excitotoxic effect of primary afferent ectopic activity on dorsal horn neurons [26]. 

The sensitivity to a flame can be affected by deposits of IR and UV absorbing materials on the lens if not frequently maintained. The IR channel can be blinded by ice particles on the lens. While the UV channel can be blinded by oil and grease on the lens. Smoke and some chemical vapors will cause reduced sensitivity to flames. UV/IR detectors require a flickering flame to achieve an IR signal input. The ratio type will lock out when an intense signal source such as arc welding or high steady state IR source is very nearby. 

A SAW device is configured as a delay line and fed by a radio frequency signal. Any change in the velocity Av is detected as a change AT in the phase delay of the wave, thanks to a phase detector that gives a voltage proportional to the difference of phase between signal input and output. 

LASL, Los Alamos, NM. The transducer described in his paper and shown in Fig 31 was in the form of an uncharged parallel-plate capacitor which had an explosive as a dielectric. One plate was connected to the signal input terminal of an oscilloscope, while the other plate was grounded and acted as part of the attenuator in the boosting system. When the shock wave in the grounded attenuator plate hir the explosive, a voltage appeared across the capacitor and a pulse appeared on the oscilloscope. Two oscilloscopes were used to record the waveform of the current in the transducer circuit which consisted of a small capacitance shunted by the small resistance of the signal cable. 

Figure 7.31 Diagram of a ns, kinetic, laser flash photolysis apparatus. F, photolytic laser beam B, continuous analytical beam S, sample cell d, light detector M, monochromator D, photomultiplier 0, oscilloscope with t (time-base trigger) andy (vertical signal) inputs, (b) Point-by-point absorption spectra of chloranil in acetonitrile at 20 ns, 1 [xj after excitation. T corresponds to the absorption by the triplet state, C by the radical anion...

Fig 2 Three-level maser amplifier, where A is signal input B is the first isolator C is the power input for pumping f) is the crystal E is the second isolator, usually operated at low temperature as a noise reflector and F is the signal output... 

Fig. 7.88. Sampling a continous signal (a) sampler switch (b) continuous signal—input to sampler (c) sampled signal—output from sampler...

It is evidently insufficient to consider only the response of a detector when analysing its usefulness for a particular application. It is generally necessary to analyse both intrinsic and extrinsic noise signals and compare them with the response. The result of this comparison can be expressed in many different ways. One of the most useful is the noise-equivalent power nep which is the power of an rms signal input (in watts) required to give a response equal to the total rms noise voltage AVN. Then ... 

EEG signals recorded by the signal conditioning system are filtered between 1 and 64 Hz and with a notch filter of 50 Hz. Amplification levels are adjusted to avoid saturation of the signal input to the computer. The differential output between the 2 cortical electrodes is digitized on-line at a sampling rate of 256 Hz/channel and the data stored in raw data files. 

An attempt was made recently to find out how sensitively the regulatory system that controls the cell cycle and cell proliferation responds to signal input. Ferrell et found that, in intact oocytes, the response is ultrasensitive , a kinetic characterization introduced by Daniel E. Koshland Jr.26 (Ultrasensitivity has been defined as the response of an enzyme that is more sensitive to changes in the concentration of the substrate than an enzyme with a normal hyperbolic response, according to the Michaelis-Menten equation. One can also use the Hill coefficient (wh) to indicate hyperbolic (Michaelis-Menten) sensitivity ( h = 1-0), ultrasensitivity ( h > l)j and subsensitivity ( h <... 

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