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Transmittance difference

Peptide transmitters Many peptides have been identified in the CNS, and some meet most or all of the criteria for acceptance as neurotransmitters. The best-defined ones are the opioid peptides (beta-endorphin, met- and leu-enkephalin, and dynorphin), which are distributed at all levels of the neuraxis. Some of the important therapeutic actions of opioid analgesics (eg, morphine) are mediated by receptors for these endogenous peptides. Substance P is localized in type C neurons involved in nociceptive sensory pathways in the spinal cord. Peptide transmitters differ from nonpeptide transmitters in that (1) the peptides are synthesized in the cell body and transported to the nerve ending via axonal transport, and (2) no reuptake or specific enzyme mechanisms have been identified for terminating their actions. [Pg.200]

Figure 10.14 Transmittance difference of the two stable states of the bistable TN vs. the retardation of the hquid crystal. Figure 10.14 Transmittance difference of the two stable states of the bistable TN vs. the retardation of the hquid crystal.
Shown in Fig. 10 are calculated Z-scan curves for both beam profiles with the same value for d>Q. Here d>o is the nonlinear phase shift at r = 0 when the sample is at the focal point z = 0 and is the on-axis intensity at the focal point. Note that the peak-valley transmittance difference, Tp. = 7 p T, obtained with the top-hat profile is approximately 2.5 times greater than that with the Gaussian beam. [Pg.437]

The 1.6% transmittance difference can appear to be a significant specimen difference if the computer printout does not specify the method of integration. [Pg.479]

Attenuation of radiation as it passes through the sample leads to a transmittance of less than 1. As described, equation 10.1 does not distinguish between the different ways in which the attenuation of radiation occurs. Besides absorption by the analyte, several additional phenomena contribute to the net attenuation of radiation, including reflection and absorption by the sample container, absorption by components of the sample matrix other than the analyte, and the scattering of radiation. To compensate for this loss of the electromagnetic radiation s power, we use a method blank (Figure 10.20b). The radiation s power exiting from the method blank is taken to be Pq. [Pg.384]

Precision In absorption spectroscopy, precision is limited by indeterminate errors, or instrumental noise, introduced when measuring absorbance. Precision is generally worse with very low absorbances due to the uncertainty of distinguishing a small difference between Pq and and for very high absorbances when Px approaches 0. We might expect, therefore, that precision will vary with transmittance. [Pg.409]

A variation on the transit time method is the frequency-difference or sing-around method. In this technique, pulses are transmitted between two pairs of diagonally mounted transducers. The receipt of a pulse is used to trigger the next pulse. Alternatively this can be done using one pair of transducers where each acts alternately as transmitter and receiver. The frequency of pulses in each loop is given by... [Pg.67]

In a discussion of the various level technologies, it is important to know the differences between the various level requirements. The implementation of a particular technology, such as ultrasonic, is different for a single alarm device than it is for a transmitter. [Pg.207]

The use of ultrasonic energy is different in on/off switches and in transmitters. Switches act on the attenuation of the acoustic signal in the gap between two crystals, while transmitters measure the time of flight of the ultrasonic pulse. [Pg.214]

A measure of the color developed by impurities when trimeUitate esters are produced can be correlated with the anhydride color measurement. The method measures the color difference in light transmittance between a trimellitic solution and a 3.0 N sodium hydroxide solution as a reference. The difference in light transmittance or AH (total color difference) is obtained using a colorimeter. [Pg.497]

Vitreous siUca transmission curves are shown in Figure 7. The hydroxyl concentration for each siUca type is Hsted in Table 9. These curves represent only the general characteristics of the different siUca types and should not be used for calculations of transmittance. [Pg.507]

A guarded hot-plate method, ASTM D1518, is used to measure the rate of heat transfer over time from a warm metal plate. The fabric is placed on the constant temperature plate and covered by a second metal plate. After the temperature of the second plate has been allowed to equiUbrate, the thermal transmittance is calculated based on the temperature difference between the two plates and the energy required to maintain the temperature of the bottom plate. The units for thermal transmittance are W/m -K. Thermal resistance is the reciprocal of thermal conductivity (or transmittance). Thermal resistance is often reported as a do value, defined as the insulation required to keep a resting person comfortable at 21°C with air movement of 0.1 m/s. Thermal resistance in m -K/W can be converted to do by multiplying by 0.1548 (121). [Pg.461]

It should be emphasized at this point that the speed of response is cnti-cal. The pressure transient pressure should not fall to less than 50% of the difference in pressure between the standby pump start pressure and the low oil pressure trip pressure. This is normally achievable with good design practice and the use of a switch and direct wiring. There is some tendency to use a transmitter and control through a remote computer. The latter arrangement is difficult to check on a shop test and normally is too slow to meet the requirement. An accumulator can be added and must be used if the requirement cannot be met. This additional hardware contributes to higher initial cost and possible reliability problems in the future. The direct switch method is therefore highly recommended. [Pg.314]

Many believe that couplings are only torque transmitters between different pi( s of equipment with a secondary function of handling everpresent misalignment. [Pg.396]


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