David Nolte and the Doppler Apparatus (IMAGE) Purdue University Caption David Nolte works with the Doppler apparatus to peer inside living cells, giving him insight into intracellular activity, metabolism, and pathogenicity Credit Purdue University photo/Rebecca McElhoe Usage Restrictions None 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.