Biology Reference
In-Depth Information
In the same issue of Nature, two other important papers were also published:
one by Watson and Crick (1953) showing the double helix model, and the
other by Wilkins, Stokes and Wilson (1953) including the following
paragraph:
“It must first be decided whether the structure consists of essentially one
helix giving an intensity distribution along the layer lines corresponding to
or two similar co-axial helices of twice the above size and
relatively displaced along the axis a distance equal to half the pitch giving
or three helices, etc. Examination of the width of the layer-line
streaks suggests the intensities correspond more closely to
than to
The is the nth order of Bessel function (see, for example, Whittaker and
Watson, 1915). It is therefore important for us to understand the properties
of Bessel function, and also the reason why helices give X-ray diffraction
patterns related to Bessel function (see, for example, Cochran, Crick and
Vand, 1952).
SOME SIMPLE PROPERTIES OF
Bessel function can be defined by the following generating function (see,
for example, Whittaker and Watson 1915):
By taking partial derivatives of G(x,t) with respect to x and t separately, we
get:
