Techne PrimeQ User Manual
Page 121
121
Setting the noise threshold and crossing line
Overview of procedure:
The noise threshold and crossing line are placed on the amplification graph either at positions
specified by the user or using the default settings.
Default values:
Noise threshold cursor: n1 = 4 SD above average of all readings x to y
Crossing line cursor:
n2 = 10 SD above average of all readings x to y
x = 3 (or 1 if number of readings less than 10)
y = 10 (or 2 if number of readings less than 10)
Once data has been obtained and displayed in the Results Editor, the thresholds will appear as
two horizontal cursors on the plot (blue for the noise threshold and red for the crossing line). Fits
points are shown as orange points above the crossing line. If necessary, the user may manually
slide the cursors to positions better suiting the data.
• The user only has to choose where to place the cursors (which are placed automatically and
then movable by the operator) – all calculations are performed automatically by the
software.
• The results (with or without correction) are plotted on a scale of log fluorescence vs. cycle
number. Although some fluorescence values may be negative, this has no effect on the
accuracy of the data.
• Up to five orders of magnitude of fluorescent data below the maximum value will be plotted
with the zero and negative values discarded.
Cycle Number
45
40
35
30
25
20
15
10
5
R
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0.01
0.1
1
10
Crossing line
Noise threshold
Cycle Number
45
40
35
30
25
20
15
10
5
R
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la
ti
v
e
F
lu
o
re
s
c
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n
c
e
(
L
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)
0.01
0.1
1
10
Crossing line
Noise threshold