Twisted elliptical fiber

Fields of local modes 19-2 Criterion for slow variation 19-3 Example Nonuniform core radius 19-4 Example Twisted elliptical fibers... 

The live, hydrated fiber exists in a tubular configuration that conforms to available space within the boll locule. When the boll opens, removal of water causes the internal layers of the fiber to twist and collapse, and the primary wall, which is less able to shrink because of its network structure, wrinkles and molds to the underlying fiber layers, producing folds and convolutions (twists), and compression marks (Figure 5.41). Fibers often collapse in a nonuniform elliptical pattern, whose cross section has a convex and a concave side (see Figure 5.27 and Figure 5.38). 

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