Inter-beat (RR) Intervals. The time intervals between consecutive heart beats are customarily measured in the electrocardiogram from the beginning of a QRS complex to the beginning of the next QRS complex, so these intervals might be called QQ intervals, but they are conventionally named RR intervals.
Dubuque County, Iowa. Dubuque County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 93,653. The county seat is Dubuque. The county is named for Julien Dubuque, the first European settler of Iowa. Dubuque County comprises the Dubuque, IA Metropolitan Statistical Area, and is the seventh largest county by population in the state.
Holy Cross is a city in Dubuque County, Iowa, United States. It is part of the 'Dubuque, Iowa Metropolitan Statistical Area'. The population was 339 at the 2000 census. Holy Cross is located at 42Â°36â²1â³N 90Â°59â²40â³W / 42.60028Â°N 90.99444Â°W / 42.60028; -90.99444 (42.600334, -90.994557). According to the United States Census Bureau, the city has a total area of 0.3 square miles (0.7 kmÂ²), all of it land.