<s>
Nuclear	B-General_Concept
computation	I-General_Concept
is	O
a	O
type	O
of	O
computation	O
which	O
allows	O
threads	B-Operating_System
to	O
either	O
spawn	O
new	O
threads	B-Operating_System
or	O
converge	O
many	O
threads	B-Operating_System
to	O
one	O
.	O
</s>
<s>
The	O
aim	O
of	O
nuclear	B-General_Concept
computation	I-General_Concept
is	O
to	O
take	O
advantage	O
of	O
threading	O
abilities	O
of	O
modern	O
multi-core	B-Architecture
processors	I-Architecture
where	O
the	O
trend	O
is	O
to	O
increase	O
their	O
hardware	O
ability	O
to	O
compute	O
more	O
threads	B-Operating_System
then	O
their	O
earlier	O
generation	O
processors	O
.	O
</s>
<s>
Nuclear	B-General_Concept
computation	I-General_Concept
focuses	O
on	O
real	O
time	O
processing	O
for	O
things	O
like	O
multimedia	O
such	O
as	O
processing	O
audio	O
where	O
a	O
real	O
time	O
deadline	O
(	O
the	O
sample	O
rate	O
in	O
Hz	O
)	O
exists	O
.	O
</s>
<s>
For	O
that	O
reason	O
it	O
should	O
not	O
block	B-Operating_System
and	O
computational	O
processes	O
which	O
alter	O
shared	O
memory	O
must	O
be	O
atomic	O
(	O
executed	O
in	O
one	O
clock	O
cycle	O
without	O
locking	O
)	O
.	O
</s>
<s>
Nuclear	B-General_Concept
computation	I-General_Concept
allows	O
a	O
computational	O
thread	B-Operating_System
to	O
use	O
thread	B-Operating_System
fission	O
to	O
turn	O
one	O
thread	B-Operating_System
into	O
many	O
or	O
thread	B-Operating_System
fusion	O
to	O
turn	O
many	O
threads	B-Operating_System
into	O
one	O
.	O
</s>
<s>
As	O
the	O
name	O
"	O
nuclear	B-General_Concept
computation	I-General_Concept
"	O
implies	O
,	O
there	O
is	O
an	O
analogy	O
between	O
nuclear	O
reactions	O
and	O
nuclear	B-General_Concept
computation	I-General_Concept
.	O
</s>
<s>
In	O
nuclear	B-General_Concept
computation	I-General_Concept
,	O
a	O
computational	O
thread	B-Operating_System
splits	O
into	O
several	O
processing	O
threads	B-Operating_System
.	O
</s>
<s>
In	O
nuclear	B-General_Concept
computation	I-General_Concept
,	O
several	O
computational	O
threads	B-Operating_System
fuse	O
into	O
one	O
processing	O
thread	B-Operating_System
.	O
</s>
<s>
Conceptually	O
fission	O
computation	O
can	O
cause	O
a	O
chain	O
reaction	O
,	O
where	O
one	O
thread	B-Operating_System
can	O
signal	O
many	O
threads	B-Operating_System
to	O
start	O
processing	O
and	O
they	O
too	O
may	O
signal	O
other	O
threads	B-Operating_System
to	O
start	O
processing	O
.	O
</s>
<s>
Fusion	O
computation	O
is	O
a	O
type	O
of	O
threshold	O
triggered	O
computation	O
,	O
where	O
several	O
threads	B-Operating_System
signal	O
the	O
single	O
waiting	O
thread	B-Operating_System
,	O
which	O
begins	O
execution	O
once	O
the	O
required	O
number	O
of	O
thread	B-Operating_System
signals	O
exceed	O
the	O
threshold	O
of	O
the	O
waiting	O
thread	B-Operating_System
.	O
</s>
<s>
A	O
previous	O
analogy	O
between	O
nuclear	O
reactions	O
and	O
computation	O
were	O
termed	O
loop	O
fission	O
and	O
fusion	O
which	O
were	O
forms	O
of	O
compiler	B-Language
preprocessing	O
.	O
</s>
<s>
Loop	O
fission	O
(	O
loop	O
distribution	O
)	O
allowed	O
one	O
computational	O
loop	O
to	O
be	O
broken	O
into	O
separate	O
loops	O
by	O
a	O
compiler	B-Language
at	O
compile	B-Language
time	O
.	O
</s>
<s>
Loop	O
fusion	O
(	O
loop	O
jamming	O
)	O
allowed	O
many	O
computational	O
loops	O
to	O
be	O
combined	O
into	O
one	O
by	O
the	O
compiler	B-Language
at	O
compiler	B-Language
time	O
.	O
</s>
<s>
These	O
processes	O
were	O
not	O
directly	O
under	O
the	O
control	O
of	O
the	O
programmer	O
and	O
were	O
decided	O
and	O
controlled	O
by	O
the	O
compiler	B-Language
.	O
</s>
<s>
In	O
contrast	O
to	O
loop	O
fission	O
and	O
fusion	O
,	O
nuclear	B-General_Concept
computation	I-General_Concept
fission	O
and	O
fusion	O
are	O
directly	O
under	O
the	O
control	O
of	O
the	O
programmer	O
or	O
the	O
program	O
at	O
run	O
time	O
.	O
</s>
