Pulse, read calibration

The pulses produced by this action proceed thru mixer circuits to an oscillograph where they are displayed on a cathode-ray oscilloscope screen along with time calibration markers. This display is photographed and detonation rates are computed from expl increment lengths, and measurements of time displacements are read on a film reader... 

The mass flow rate is calculated directly by multiplying the time difference or the phase shift with the calibration constant of the flowmeter thermal effects on the mass flow and density reading have to be included as well. This is commonly done with a microprocessor. The primary output from a CMF is mass flow. However, most electronic designs are also capable of providing temperature, density, and volumetric flow data. Further, totalizers provide mass or volume totals. Analog (4 to 20 mA) and digital output protocols are supported (e.g., PROFIBUS, FOUNDATION Fieldbus, HART, Modbus, scaled pulse, and others). 

The radiation has to be chopped, and so the detector receives pulses of radiation from the source and the chopper alternately. Therefore the temperature is measured relative to the temperature of the chopper surface. In practice, radiometers are calibrated so that the temperature can be read directly from a scale. A particular commercial model which operates over the temperature range 0-600 °C uses a LiTa03 single crystal as the pyroelectric detector. 

Inhomogeneity in the applied rf field means not all nuclei within the sample volume experience the desired pulse flip angle (Fig. 9.1b), notably those at the sample periphery. This is similar in effect to the (localised) poor calibration of pulse widths and references to rf (or Bi) inhomogeneity below could equally read pulse width miscalibration . Modifications that make sequences... 

In 1993 Weiss, Riley, and co-workers reported a study on purported SOD mimics by stopped-flow UV-vis spectroscopy (428) in which they assessed reactivity by following the decay of the superoxide absorption at 245 nm. Two of the earlier techniques that had been used to assess SOD activity included observation by UV-vis spectroscopy of the oxidation of nitroblue tetrazolium (NBT) (68) or the oxidation of a cytochrome c by superoxide (52). Both systems used superoxide from an in situ generator, frequently xanthine oxidase, wherein the complex being analyzed was compared to a calibrated oxidation of the chromophore alone and in the presence of MnSOD. The direct observation of the decrease in the superoxide signal with time by UV-vis is also possible, and superoxide may be introduced as a solution (428) or generated, in some cases, by pulsed radiolysis (79, 80). In these direct observation experiments, the rate of decay of superoxide in the presence of the complex is compared to the rates of decay of superoxide alone and in the presence of one unit of activity of MnSOD. In all cases, the systems are usually referenced, or calibrated, against the same set of conditions with MnSOD. Due to interactions with cytochrome c with components of assay mixtures other than superoxide, false readings of activity were often observed for some early SOD mimics. The NBT, stopped-flow, or pulsed radiolysis techniques have tended to provide the more accurate answers on the ability of reputed MnSOD mimics. To be considered active in any manner with respect to the decay of superoxide in the stopped-flow analyses, Weiss et al. stated that compounds based on their analyses needed to exhibit kcat values in excess of 10B 5 M 1 s 1 (428). 

By introducing a controlled charge and discharge time, a quasipeak detector is achieved. The charge and discharge times may be selected, for example, to simulate the ear s sensitivity to impulsive peaks. International standards define these response times and set requirements for reading accuracy on pulses and sine wave bursts of various durations. The gain of a quasipeak detector is normally calibrated so that it reads the same as an RMS detector for sine waves. 

The Log N Channel reads current from a -compensated ionization chamber located in the thermal column. It is calibrated in watts over the range 10 -10 W. The Log N detector (Figure 4) is a voltage-compensated B -lined ion chamber. Rather than counting pulses, as the Log Count Rate channel does, the Log N reads a current due to ionization of the filling gas from the (n, ) Li reaction. 

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