E Calvin Alexander

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BACKGROUND Contrasting biological, chemical and hydrogeological analyses highlights the fundamental processes that shape different environments. Generating and interpreting the biological sequence data was a costly and time-consuming process in defining an environment. Here we have used pyrosequencing, a rapid and relatively inexpensive sequencing(More)
The development of a karst feature database for southeastern Minnesota. Southeastern Minnesota is part of the Upper Mississippi Valley Karst (Hedges & Alexander 1985) that includes southwestern Wisconsin and northeastern Iowa. Karst lands in Minnesota developed in Paleozoic carbonate and sandstone bedrock. A significant sandstone karst has developed in Pine(More)
  • Edward Frank, Carol Wicks, John Mylroie, Joseph Troester, E Calvin Alexander, James Carew +4 others
  • 2001
Isla de Mona is a carbonate island located in the Mona Passage 68 km west of Puerto Rico. The tec-tonically uplifted island is 12 km by 5 km, with an area of 55 km², and forms a raised flat-topped platform or meseta. The meseta tilts gently to the south and is bounded by near vertical cliffs on all sides. These cliffs rise from 80 m above sea level on the(More)
Underwater exploration at Sistema Zacatón reached human limits when Jim Bowden descended to a depth of 289 meters April 6, 1994. In order to understand this karst system, unmanned robotic exploration is required to document the immense geometry of the underwater caves. The DEPTHX (DEep Phreatic THermal eXplorer) vehicle was developed with support from NASA(More)
Septic systems that are built in compliance with regulations are generally not expected to be the cause of groundwater borne disease outbreaks, especially in areas with thick vadose zones. However, this case study demonstrates that a disease outbreak can occur in such a setting and outlines the combination of epidemiological, microbiological, and(More)
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