Information Technology Reference
In-Depth Information
50
50
1000 iterations
40
40
30
30
4000 iterations
10000 iterations
20
20
10
10
2D model
bitstring model
0
0
10
15
20
25
30
35
40
45
50
6
7
8
9
10
11
12
Recognition radius
Affinity Threshold
Fig. 4.
Comparison of antigen tolerance in 2D and bitstring models
However, as their concentration is decreased according to
stimulation/
(100
L
),
if
L
= 100 then in practice, an actual decrease in concentration is only observed
when the total stimulation exceeds 10000 (concentration takes integer values
only in the model). Therefore, antigens will be rejected from the exactly the
same upper zones of the diagram shown in the previous antibody figure where
stimulation
>U
.
The shape of the boundary separating the regions, and the resulting ability
of the network to reject or tolerate antigen is dependent on the radius of the
recognition region used. The left hand side of figure 4 illustrates the number of
antigens tolerated by the network when a set of 50 randomly generated anti-
gens are presented to the network at iteration
i
and evolution continued for a
∗
6000
6000
Stimulation received by an antigen at site
Stimulation received by an antibody at site
5000
5000
4000
4000
3000
3000
2000
2000
1000
1000
0
0
S<U
L<S<U
S>U
S<L
S>L
1400
1200
1000
800
600
400
200
0
0
50
100
150
200
250
field experienced by cell
Fig. 5.
Field experienced by cells occupying each potential site of the grid following
emergence of the network. In the upper diagrams,S=stimulation, L=lower limit (100)
and U=upper limit (10000). Field refers to stimulation calculated using constant con-
centration of 1.
