Let and be the modulus of convexity and the Domínguez-Benavides coefficient, respectively. According to these two geometric parameters, we obtain a sufficient condition for normal structure, that is, a Banach space has normal structure if for some which generalizes the known result by Gao and Prus.
"Modulus of Convexity, the Coeffcient , and Normal Structure in Banach Spaces." Abstr. Appl. Anal. 2008 1 - 5, 2008. https://doi.org/10.1155/2008/135873