Stefano Rivella, Ph.D. (IMAGE) Children's Hospital of Philadelphia Caption Stefano Rivella, Ph.D., Kwame Ohene-Frempong Chair on Sickle Cell Anemia and Professor of Pediatrics at CHOP. Credit CHOP Usage Restrictions Request permission from CHOP License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.