Signal Gain

Microwave power Sweep width 1 st or 2nd harmonic Signal gain... 

The screen must be very sensitive in its detection of potential effective agents. An absolute minimum of active agents should escape detection that is, there should be very few false negatives (in other words, the type II error rate or beta level should be low). Stated yet another way, the signal gain should be way up. 

The dominant attribute that has driven interest in fluorescent conjugated polymers (CPs) sensory materials is their ability to produce signal gain in response to interactions with analytes. The increased sensitivity (amplification) is derived from the ability of a conjugated polymer to serve as a highly efficient transport medium of electronic excitation. Analyte specificity in CP-based sensors results from the covalent or physical integration of receptors, imprinting, and/or the CP s overall electrostatic and chemical characteristics. The observed amplification is a... 

The photomultiplier tube a very sensitive device that has a linear response over seven decades - has for a long time been the most widely used detector in spectrophotometers. Its efficiency depends on the yield of the photocathode, which varies with wavelength (e.g. 0.1 e /photon at 750 nm). and with the signal gain provided by the dynode cascade (e.g. gain of 6 x 105). With such values, the impact of 10000 photons per second produces a current of 0.1 nA. 

Avalanche Photodiode (APD)—A photodiode designed to take advantage of avalanche multiplication of photocurrent. As the reverse-bias voltage approaches the breakdown voltage, hole-electron pairs created by absorbed photons acquire sufficient energy to create additional hole electron pairs when they collide with ions thus a multiplication or signal gain is achieved. 

Thus, the signal gain depends upon the ratio Rf/R. Figure 6.626 represents a buffer amplifier or voltage follower in which V0 = V,. This has the high input and low output impedances necessary to obviate the kind of inter-element loading problems illustrated in Section 6.11.6. For a more detailed treatment the reader is referred to Smith 881. 

Shown in Figure 7.9 [8] is the influence variations in gas temperature and electron density have on small-signal gain, a0. This calculation was carried out for a 1-1-8, C02-N2-He mixture for a fixed-discharge EjN typical of laser operating conditions. The conditions depicted in Figure 7.9 correspond to a... 

Figure 7.9 Variation of small signal gain, a0 with gas temperature and electron density for a 1-1-8 laser mixture and reduced average electron energy of 1.5 eV [8].

A stepwise increase of the reaction temperature led to deeper reduction, as evidenced by a rising UV-vis absorbance > 500 nm (Fig. 18A). At the same time, the two EPR hyperfine signals gained in intensity, as did the broad isotropic... 

To improve the signal-to-noise ratio in NMR, the data acquired under similar conditions are added. The signal gains in proportion with the number of scans, while the variance... 

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