ANALYZE software manual
During practical classes, a custom-made software (ANALYZE) will be used to
measure and visualize different physiological variables as well as to analyze effects
induced by experimental manipulations. Physiological variables are transformed into
electric signals by appropriate sensors (strain gauge, blood pressure probe, etc.) connected
to the amplifier. Amplified (analog) signals are digitalized by an analog-to-digital
converter card (A/D converter) installed into the computer. Digitalization means that the
converter measures the input voltage at preset intervals (sampling time or sampling rate)
and passes the value in numeric form to the computer. The A/D converter we use,
generates 12-bit binary numbers between -2048 and 2047 (-212 – 212-1).
ANALYZE program consists of a measuring and an analysis module. To switch
from one module to the other, the “Analyze” or “Measure” menu points should be
selected, depending on which module is active. The software is able to measure and
analyze three signals in parallel. While many different physiological parameters can be
monitored by the program, their measurement (and analysis) fits into one of two basic
types.
In continuous mode, input signals are digitalized at the preset frequency and the
resulting numeric values are stored and displayed on the screen in parallel with
measurement, in real-time. This mode emulates an ink-writer, that records signals on a
paper strip. Maximal sampling rate depends on the number of measured signals and on
computer performance.
Considerably higher sampling rate can be achieved in block mode. Measurement
of input signals is started by user command. The time-consuming display of the acquired
data is postponed until the preset number of data points is taken. Thus, measurement is
not continuous, it occurs in separate blocks. During analysis, data acquired in blocks can
be treated as continuous and vice versa. In this way, special features provided by the two
types of analysis can be used independently of the method by which the data was
collected.
All necessary information for using the program is provided on the pages below
describing user screens and menu commands for continuous and block modes during
acquisition and analysis. Before hints and special information to complete the first
experiment, “Calibration” are given, a short overview of the connections between the
amplifier and computer follows. Input “BNC” sockets (1-8) of the A/D converter are
found on the top of a small black box, which is connected to the converter installed in the
computer through a gray flat cable. These input sockets should be connected to the
outputs of the amplifier. The output (“jack”) sockets are located on the rear panel of the
amplifier (SG – strain gauge, etc.). For the sake of simplicity, if one signal is measured it
should be connected to the first socket. In the case of two input signals, the first two
sockets should be used, and so on.
Experiment 1. Calibration
The goal of this experiment to get familiar with the components of the data
acquisition system: the displacement sensor (strain gauge), the amplifier and the software.
a/ In continuous measurement mode click on the downward arrow of the first
(white) channel to activate the drop-down list and select the first input socket (1.ch) to
which the strain gauge (SG) output of the amplifier is connected. Gain should be left at
the default value (1x). Three signals can be measured simultaneously by the program, but
there are only one set of buttons to control the position and scaling of the three curves
(white, yellow, blue) on the display. On the right side of the display, there are three small,
color-coded buttons to assign the controls to one of the three signals. The white one
should be selected. Assignment of the buttons to another signal is indicated by a change
in the color of controls and y-axis.
b/ Set scaling on y-axis to the maximal useful range (-2000 – +2000). Sampling
rate should be 50 Hz, screen length 30 s. Start sampling and displaying of the signal by
pressing “Monitor” button.
c/ Move the curve to the bottom of the display by turning the offset dial on the
amplifier. Make sure that the curve can still move a little bit downward if you carefully
touch the lever of the displacement sensor with your finger. If amplification or offset is
too large then the curve is locked to the upper or lower limit and is insensitive to the
displacement of the sensor. If this phenomenon is caused by inappropriate scaling of the
y-axis, then data stored into the disk file is still usable. However, if the amplified signal at
the input of the A/D converter exceeds ±10 V, which is the maximal value that the
converter can pass to the computer as ±2048, the measurement should be repeated.
d/ Before the actual experiment, determine which is the largest weight that does
not cause locking of the curve to the upper limit (2048) of the display. Please note that the
curve on the display is displaced upward when the weight is pulling the lever of the
sensor downward. During experiments in the following weeks, always test the
relationship between the displacement of the lever and the curve on the display by
carefully moving the lever of the strain gauge. This information is crucial for the
evaluation of your observations. Finding out if the frog’s heart stopped in contracted or
relaxed state, has a large impact on interpretation.
e/ After the largest weight to be used has been determined, arrange the weight in
ascending order and open a data file by pressing the “Record” button. It is advisable to
give the files unique, meaningful names. You do not have to specify the extension of the
file (the part after the “.” character), the program will set it automatically to “.bin”. File
length should be the default value of 180 s. Let’s recording and displaying baseline data
for a few seconds (10-20), then put on the first weight carefully. Wait until the transients
are over, record the displacement caused by the weight for a few seconds, then remove
the weight. After a short baseline recording, put on the next weight and repeat the
procedure until the largest weight has been measured. Close the data file by pressing the
“Stop” button.
f./ Select “Analyze” from the menu and open the data file (“File/Open”). If you
press the left mouse button over the blue display area within the range of the curve, a
cursor line appears. Position the cursor over the first baseline period. Press “Add” button.
You are prompted for a label by the program. The label will be transferred together with
the mean and standard deviation values to MS Word, where the report can be written.
Give the value of the first weight as label (e.g. “5 g”). Move the cursor to the period
where the effect of the first weight is seen and press “Add” again. Go back to the baseline
and repeat at least three times the measurements. Note that the “Add” button is always
selected (a dotted frame within the button marks the selection), thus pressing the “Enter”
on the keyboard has the same effect as clicking on the button with the mouse. Therefore,
it is easier and faster to use the mouse only to position the cursor, while activating the
“Add” button from the keyboard. In this way, there is no need to repeatedly move the
mouse pointer between the curve and the “Add” button. When three data pairs have been
measured and entered into the table at the bottom of the screen, press the “Newblk”
button to terminate analysis of the first weight’s effect. Mean and standard deviation is
automatically calculated from the data.
g./ Repeat these measurements for all weights. When ready, put labels on the
curve above each displacement, indicating the values of the weights. This can be done by
activating the “Text/Insert” menu point. A new textbox will appear in the top left corner.
After typing the text, the box can be dragged to the appropriate position with the mouse.
Labels can be reselected with the mouse and edited if necessary. Empty textboxes are
automatically deleted. The “Text/Delete” menu point removes the selected label. When
the figure is ready, select the “Copy/Picture” menu point to copy it to the clipboard.
Locate and launch MS Word. Paste the figure into a new document, and switch back to
Analyze. Make sure that when you switch between the running applications, you do not
restart a new instance of programs. Use the “Alt-Tab” key sequence, or another method.
Launching several copies of the same program, especially Analyze can crash the system
resulting in possible loss of data. Select the “Copy/Block means” menu point in Analyze
to copy mean and standard deviation values to the clipboard. Paste these values into the
same document in Word and then everything is ready for the preparation of the report.
h./ Using weight values and mean displacement data, a calibration curve can be
constructed, preferably in MS Excel and inserted into the report. Make sure that you
select “Scatter” diagram in Excel and not “Line”, otherwise weight values will be ignored
and displacement values will be evenly distributes along the x-axis.
Menu points and settings in continuous measurement:
File
Exit
Display
Block mode
Analyze
terminate program
no menu point can be selected
change to block mode, specifying block length
switch to analysis module
increase amplitude
move curve upward
select between
channels
display mode
(read only)
move curve upward
decrease amplitude
monitor w/o storing
measure and store
marker on/off
stop measurement
give stimulus
select channel
to measure
sampling frequency
gain of the A/D
converter
displayed epoch
maximal stored length
Menu points and settings in block measurement:
File
Display
Exit
terminate program
Single/Average
display single curve with white/yellow/cyan color and average with dark gray in the background
Average/Single
display averaged curve with white/yellow/cyan color and single with dark gray in the background
Single
display only single curves with white/yellow/cyan color
Average
display only averaged curves with white/yellow/cyan color
Block length
change block length
Continuous
change to continuous mode
Analyze
switch to analysis module
add single curve
to average
clear average
save last single curve
into the previously
opened data file
open data file
stop acquisition,
close data file
number of averaged curves
delay to first stimulus
interval between stimuli
number of stimuli to deliver
Menu points of analysis in continuous mode:
File
Open
Exit
open data file
terminate program
Copy
Picture
Block means
Whole table (Excel)
Whole table (Word)
Curve points
copy figure to clipboard
copy statistical data (mean, standard deviation, n) to clipboard
copy individual cells of the table to the clipboard in Excel compatible form
copy individual cells of the table to the clipboard in Word compatible form
copy curve points to the clipboard
Zoom
Expand
Compress
Zoom selection
displayed curves are expanded (x-axis range is decreased to half)
displayed curves are compressed (x-axis range is doubled)
epoch selected with the right mouse button is expanded to fill the display
Display
no menu point can be selected
Invert
invert displayed curve (multiply by –1)
Marks off
clears cursors positioned with the right mouse button
Text
Insert
Delete
insert label to the figure
delete label from the figure
Auto peaks
automatic location of peaks in the epoch selected with the right mouse button taking into account lower and
upper limits set with the mouse pointer
Block mode
change to block mode specifying block length
Measure
switch to continuous measurement mode
User screen of analysis in continuous mode:
step backward half screen
step forward half screen
put selected data
point into the table
clear table
close analysis epoch
delete last line in
table
x1
y1
x2
y2
ampl.
tone
period
time of the first extreme value (peak or trough)
amplitude of the peak or trough
time of the next, opposite extreme value (trough or peak)
amplitude of the trough or peak
absolute difference of the two amplitudes (peak-to-peak amplitude)
average of the two amplitudes, i.e. middle point of the wave
time from the previous x1, i.e. distance between the two waves
Menu points of analysis in block mode:
File
Open
Exit
open data file
terminate program
Copy
Picture
Whole table (Excel)
Whole table (Word)
Curve points
copy figure to clipboard
copy individual cells of the table to the clipboard in Excel compatible form
copy individual cells of the table to the clipboard in Word compatible form
copy curve points to the clipboard
Zoom
Expand
Compress
Zoom selection
displayed curves are expanded (x-axis range is decreased to half)
displayed curves are compressed (x-axis range is doubled)
epoch selected with the right mouse button is expanded to fill the display
Display
Single/Average
Average/Single
Single
Average
Overplot
Raw curves
PSD
display single curve with white/yellow/cyan color and average with dark gray in the background
display averaged curve with white/yellow/cyan color and single with dark gray in the background
display only single curves with white/yellow/cyan color
display only averaged curves with white/yellow/cyan color
display blocks under each other (waterfall)
curves are displayed as measured, in the time frame
Power Spectrum Density) histograms of the curves are displayed
Invert
invert displayed curve (multiply by –1)
Marks off
clears cursors positioned with the right mouse button
Text
Insert
Delete
insert label to the figure
delete label from the figure
Block length
change block length
Continuous
change to continuous mode
Measure
switch to continuous measurement mode
User screen of analysis in block mode:
step back one block
step forward one block
t
A
t-dly
p-to-p
dist
time of the extreme value (peak or trough) from the beginning of the curve
amplitude of the peak or trough calculated from the baseline (prestimulus period)
time of the peak or trough from the stimulus (delay)
signed amplitude difference of the peak or trough from the previous extreme value (A2-A1)
time from the previous extreme value (t2-t1)