Baseline smoothing

Software function Variation of signal amplitude Signal and temperature calibration Accumulation and storage of data Baseline smoothing... 

General (DTA, DSC, TG, TMA, DMA) Variation of signal amplitude Signal and temperature calibration Accumulation and storage of data Baseline smoothing" Display and calculation of transition temperatures Display of multiple curx es Curve subtraction Derivative TA curve Baseline correction"... 

ND 60.dat Fifteen columns that each contain 160 random numbers. To be used with MSD, HISTO, CORREL, SMOOTH to obtain a baseline, against which to compare real data sets the ruggedness of evaluations can be checked through comparisons with sets of random numbers. 

Table 1.2 The excess inter-electronic repulsion for T configurations (column 4), relative to a smoothly varying baseline function, g(n), drawn through the formulae for f, f and f. ...

A typical MALDI spectrum of a bacterial sample has a number of peaks that vary greatly in intensity superimposed on a relatively noisy baseline. This can be problematic for many peak detection routines. Therefore methods that eliminate the need for peak detection also eliminate problems associated with poor peak detection performance. Full-spectrum identification algorithms use the (usually smoothed) spectral data without first performing peak detection. 

A typical measurement was performed as follows. The feeder was lowered into the crucible and the sample solution (seawater) was allowed to flow under an inert atmosphere with the suction on. A constant current was applied for a predetermined time. When the pre-electrolysis was over, the flow was changed from the sample to the ammonium acetate washing solution, while the deposited metals were maintained under cathodic protection. Ammonium acetate was selected for its low decomposition temperature, and a 0.2 ml 1 1 concentration was used to ensure sufficient conductivity. At this point the feeder tip was raised to the highest position and the usual steps for an electrothermal atomic absorption spectrometry measurement were followed drying for 30 s at 900 C, ashing for 30 s at 700 °C, and atomization for 8 s at 1700 °C, with measurement at 283.3 nm. The baseline increases smoothly with time as a consequence of an upward lift of the crucible caused by thermal expansion of the material. 

Kotlikoff Returning to the issue of receptor-operated or store-operated channels, one of the things I noticed in your traces was that your caffeine responses came back to baseline very smoothly. There was not the sustained elevation of [Ca2+] that you might predict. One of the things that is very different about voltage-clamped smooth muscle between a caffeine response and a phospholipase receptor-linked response is this additional current that is seen with the phospholipase receptor. I didn t see any functional evidence of a sustained response in your caffeine experiments. Have you voltage clamped these cells and looked to see whether there is any current there If not, do you think this is because the current is just too small to be able to measure ... 

If the x-data of an object are time-series or digitized data from a continuous spectrum (infrared, IR near infrared, NIR) then smoothing and/or transformation to first or second derivative may be appropriate preprocessing techniques. Smoothing tries to reduce random noise and thus removes narrow spikes in a spectrum. Differentiation extracts relevant information (but increases noise). In the first derivative an additive baseline is removed and therefore spectra that are shifted in parallel to other... 

Expiration The expiratory limb is a smooth curve. At high lung volumes, the compliance is again low and the curve flat. The steep part of the curve is around FRC as pressure returns to baseline. 

Tlic first set of preprocessing tools discussed are those that operate on each sample. Table 3.1 lists the four methods discus.scd normalizing, weighting, smoothing, and baseline corrections. Norntalization can be used to remove... 

Detector sensitivity is one of the most important properties of the detector. The problem is to distinguish between the actual component and artifact caused by the pressure fluctuation, bubble, compositional fluctuation, etc. If the peaks are fairly large, one has no problem in distinguishing them however, the smaller the peaks, the more important that the baseline be smooth, free of noise and drift. Baseline noise is the short time variation of the baseline from a straight line. Noise is normally measured "peak-to-peak" i.e., the distance from the top of one such small peak to the bottom of the next. Noise is the factor which limits detector sensitivity. In trace analysis, the operator must be able to distinguish between noise spikes and component peaks. For qualitative purposes, signal/noise ratio is limited by 3. For quantitative purposes, signal/noise ratio should be at least 10. This ensures correct quantification of the trace amounts with less than 2% variance. The baseline should deviate as little as possible from a horizontal line. It is usually measured for a specified time, e.g., 1/2 hour or one hour and called drift. Drift usually associated to the detector heat-up in the first hour after power-on. 

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