Closed Loop Solitons and Sigma Functions: Classical and Quantized   Elasticas with Genera One and Two
  Closed loop solitons in a plane, whose curvatures obey the modified Korteweg-de Vries equation, were investigated. It was shown that their tangential vectors are expressed by ratio of Weierstrass sigma functions for genus one case and ratio of Baker's sigma functions for the genus two case. This study is closely related to classical and quantized elastica problems. 
Shigeki Matsutani