Long term drifts

If the relaxation con slaii I is large lb ere is lilllc effect on a trajectory apart from the long term drift towards fluctuation about and... 

Short- and long-term drift in the spectral output can be caused by several factors drift in the output of the infrared light source or of the electronics, aging of the beam splitter, and changes in the levels of contaminants (water, CO2, etc.) in the optical path. These problems are normally eliminated by rapid, routine calibration procedures. 

The last column of Table 10-6 shows the combined reset errors to be comparable with the counting error. (The subtraction of variances is justified because long-term drift had been proved absent in the first... 

For simplicity, we will assume that depth below the sea bottom varies linearly with time. The first step in the calculation consists in removing the long-term drift over the whole period by fitting the data with a parabola and determining a periodogram out of the residuals from this fit. Depth has also been scaled to 1 in order to minimize round-off errors. Applying the method shown above, the best-fit parabola is obtained for... 

An easy calibration strategy is possible in ICP-MS (in analogy to optical emission spectroscopy with an inductively coupled plasma source, ICP-OES) because aqueous standard solutions with well known analyte concentrations can be measured in a short time with good precision. Normally, internal standardization is applied in this calibration procedure, where an internal standard element of the same concentration is added to the standard solutions, the samples and the blank solution. The analytical procedure can then be optimized using the internal standard element. The internal standard element is commonly applied in ICP-MS and LA-ICP-MS to account for plasma instabilities, changes in sample transport, short and long term drifts of separation fields of the mass analyzer and other aspects which would lead to errors during mass spectrometric measurements. 

Figure 21 and Table 3 summarize the necessary DC-sources applied to the structures of the chip. Presently all DC-sources are programmable and variable in the range of-230 to +230 V. This flexibility is essential to determine the optimal parameter setting during system optimization. Once it is known many of these sources can be replaced by fixed ones. Still, due to production tolerances and long term drift effects the sources for ion extraction and focus (t/IFO), energy filter (Usl, Uso), and MCP (UHV) will have to remain variable for optimum device performance. 

In order to compensate for short-term or long-term drift effects, a protocol is followed which alternatively measures serum and calibration standards. 

A long-term drift or dmg tolerance has also been described.This observation may also resnlt from changes in disease state or noncompliance in certain patients rather than as tolerance to timolol per se. Nevertheless, less than half the eyes initially treated with timolol or other P-blockers can be expected to be treated with the original medication after 5 years. The remainder of eyes generally requires either additional medication... 

BogerWP.Timolol short term escape and long term drift. Ann Ophthalmol 1979 11 1239-1242. 

Steinert RF,Thomas JM BogerWPI. Long-term drift and continued efficacy after multiyear timolol therapy. Arch Ophthalmol 1981 99 100-103. 

Tachyphylaxis can develop after treatment with ophthalmic beta-blockers (366). There are two forms, short-term escape, which occurs over a few days, and long-term drift, which occurs over months and years. 

The flow rate of the chromatographic apparatus must be extremely stable and reproducible Flow rate fluctuations about the specified value should be lower than 3%, and long-term drift lower than 1%. Repeatability of flow rate setting is extremely important, as a 1% constant deviation of the actual flow rate from the... 

The first line of Table 10.5 indicates short-term repeatability. The second line indicates the reproducibility of the calibration procedure, based on six recalibrations over a 10-day period. Long-term drift is indicated by the third line, over a period of time selected by the user, with recalibration. These results may be used to verify specifications claimed by the manufacturer and to provide a baseline for future measurements. Table 10.5 provides an assessment of the Raman shift accuracy of a particular instrument, obtained using samples and procedures that should be similar to the intended application. 

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