Figure 2.

Schematic diagram showing a B. burgdorferi cell. The cell cylinder is gray and the periplasmic flagella are treated as a single helical filament, shown in black. The centerline of the cell cylinder, described by the vector, r_c, is depicted by the dashed line. r_f is the vector describing the centreline of the periplasmic flagella. (Inset) A close up view of a short segment of the cell. ${\hat{\mathbf{e}}}_1$ and ${\hat{\mathbf{e}}}_2$ are unit vectors that point to the surface of the cell cylinder. The flagella are located at a point a${\hat{\mathbf{p}}}_1$ from the centreline. α is the angle from ${\hat{\mathbf{e}}}_1$ to ${\hat{\mathbf{p}}}_1$.