FFTINS.TXT

While many compromises have to be made in modelling, the twins are identical to a degree unlikely to be achieved in life, and it is certain that any changes seen when A-V anastomoses are introduced can only be due to that cause.

The model is written in DOS for code efficiency (using Borland 'C' for DOS)   It runs entirely in the lowest 640k of memory, so avoiding any clashes with programs in upper memory   However this compiler has no "knowledge" of Windows or other programs that may use the top of lower memory for small bits of "lead in" code to other applications.   This program needs just over 300K of memory for itself and requires extra to temporarily store images while control panels are displayed etc.   Windows98 seems able to cope with this in it's DOS window but other installations may not.   It is best to exit Windows completely to DOS before running FFT.EXE.   Similarly, running the program from the floppy to which it was down loaded means that when the session is closed the hard disc has not been touched (all temporary stores are to memory, not disk).   The program is self contained and can of course be copied to C:> from which it will start more quickly, or any where else, if desired.
     
  
CONTROLS ETC.

Controls and control information are accessed via the [?] key 

[Space] steps through any linked menus used, eventually returning to a running model. 

[Q] quits the program.   


The primary control panel is seen following pressing of [?].   It carries a series of presets to set up anastomoses etc.   Anastomotic patterns produced are illustrated in a small yellow panel in the top right screen.  Pressing [space] will return the program to running, or pressing [enter] allows selection of further presets 

    
[<] or [>] 	selects the direction of A-V anastomoses 
			being adjusted.  The number of anasomoses
			may be increased with the up-arrow key or 
			decreased with the down arrow.   

[A]			Pressing [A] steps through the sequence 
			1.No connection, 
			2.Direct (cord insertion)-(cord insertion) 
			3.Indirect (from twin A's cord insertion
			  to part way down B's Chorionic artery 
			  tree.   
			Since if hearts remain synchronous the 
			beat patterns observed in life can not 
			occur a 3% difference in heart rate is 
			introduced when [A] is selected.   If 
			required this rate difference can be 
			removed by pressing [h]   In general this 
			will not restore synchrony and a net 
			pressure difference will result which 
			could not be sustained in nature   

[V] 			Introduce a V-V anastomoses.

[K]			Selects skin keratinisation, then
	 [+] or [-] allows adjustment of skin 
			permeability .

[G/g]		Re-configures the fetuses to represent 
			27/12 wk gest.age e.g. Renal development,
			Hct, blood protein content, skin 
			permeability etc.

[?] again      Displays key strokes for simulated 
			experiments ("in-syntho") while the 
			program is running, such as blood 
			sampling, amniotic fluid drainage (amnio-
			reduction), fetocide etc.   Others adjust 
			display parameters such as time scale, run 
			speed or numeric display of current 
			values.

[?] again		Lists the various displays that are 
			provided, accessed while the program is 
			running by use of the numeric keys.   

FAMILIARISATION SUGGESTIONS

It is suggested that initially the downloaded program is run using the floppy disc in drive a:, i.e. 

If in WINDOWS98 click on the MS-DOS icon.
If in WINDOWS other than Windows98 exit to DOS

Insert the disc in drive a:  

Type  "a: <ENTER>"
The prompt should change to "a:>"

Type "FFT" <ENTER>
The program should start, briefly showing a title page, and then the main pictorial summary page.   

Press [7] and allow to stabilise.   
Display (1) has extensive graphics code causing it to run more slowly than the graphically simpler time plots 6,7,8,9; see the model time print at bottom left corner.   (In a commercial product all preset values would have been adjusted to match those after stabilisation.   This model is simply a copy of the current version constantly being extended as required to test new hypotheses in our research.   This disturbs the natural values and as there are over a hundred variables that would have to be adjusted it is only practical to update the major ones and allow the model to self adjust the rest, as indeed happens in nature.)  

Press [Pg Dn.] Another set of variables becomes visible. Return to upper set with [Pg Up].

Press [T]  Each press cycles through a range of plotting time scales which eventually loop back to the sarting scaling    

Observe other plotting modes [8],[9]

Introduce an anastomosis
[?]			To select main info panel  

[<]			Add some AVAs,[up or down arrow] 
			The pattern is displayed in the small 
			yellow panel in top right of screen .
[>]            Repeat in opposite direction.

[Space]        Program resumes running and if in d7,d8,or 
			d9 marks trace with dotted timing 
			indication and label of current AVA 

[?]			Now remove the AVAs as above, press [space]		 and allow to restabilise

[A]			Repeated pressing of [A] cycles through 
			various AVA connections.   select direct 
			cord-cord conection.
[6]			This specialises in showing flow patterns 
			through an AAA in the presnce of other 				anastomoses   Note that although the mean 
			flow is zero, the reciprocating flow is 
			quite large.   On some modern computers 
			this display may be too fast to observe, 
			press [Z] to slow the the display rate, 
			and [W] (wait) to toggle screen freeze if 
			required.   

[?],[<] 		Go to main control panel

[Up arrow],[up arrow]  
			Introduce a unidirectional anastomotic 
			pattern.

[space]		The mean flow is offset because the AAA is 
			acting as a return flow channel

[?],[H],[H],[space]	
			Increasing the heart rate difference, 
			makes the difference pattern occurs more 
			frequently.

Notes: 

Some studies may require graphics from different displays.   Since the computer program runs identically each time for a given input it is possible to combine results from separate runs, provided the timing of adjustments are accurately reproduced.   A small time marker dot has been placed on the centre trace, and for accurate timing the program can be temporarily toggled slow running by pressing [Z].

At the end of the traces 7,8,9 the program waits for a space bar press.  This is to allow screen captures for recording purposes.   Page down and page up work normally and can be used to present both upper and lower pages to any screen capture facility.

Other facilities can be selected as shown on control panels mentioned above.

This program is merely a copy of one of our research tools currently in use, not a finalised product.   It may be freely copied, but if used as part of a publication a simple acknowledgement would be appreciated.  

Since Fetal Charlotte models are 'working tools' in our research they are modified from day to day as required and are not protected from parameter settings that may take variables outside their mathematical limits.   If the program appears to 'hang up' try combinations  of [Q] and [Space] which should eventually exit the program and allow you to restart it.   Some keys require double presses where we program in temporary options which are not possible in this .EXE version.  If it hesitates repeat the key.   
The program will run from this floppy, but will start faster if copied to hard disc.