Ragweed Study Equipment (IMAGE) Johns Hopkins University Caption Johns Hopkins graduate students Mike Martin and Marcelo Chamecki used high-tech and low-tech equipment to study the spread of ragweed pollen in this 18- acre field near Washington, D.C. Credit Will Kirk/JHU 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.