The use of restriction enzymes as a way to cut DNA molecules was first demonstrated in a classic study by Johns Hopkins biochemist Daniel Nathans and his graduate student Kathleen Danna (Danna & Nathans, 1971).
Home : Climate Graphs: Pennsylvania : Philadelphia. Philadelphia's coldest month is January when the average temperature overnight is 25.5Â°F. In July, the warmest month, the average day time temperature rises to 85.5Â°F.
The average surface water temperature in Philadelphia is rapidly decreasing during October, falling by 8Â°F, from 68Â°F to 59Â°F, over the course of the month. Average Water Temperature in October