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A comparative (15)N-tracer study of nitrogen dynamics in headwater streams from biomes throughout North America demonstrates that streams exert control over nutrient exports to rivers, lakes, and estuaries. The most rapid uptake and transformation of inorganic nitrogen occurred in the smallest streams. Ammonium entering these streams was removed from the(More)
The use of a combination of the stable isotopes of sulfur, carbon, and nitrogen allows the flow of organic matter and trophic relations in salt marshes and estuaries to be traced while eliminating many ambiguities that accompany the use of a single isotopic tracer. Salt-marsh grasses take up the isotopically light sulfides formed during sulfate reduction,(More)
OBJECTIVE To investigate the association of PD with preceding head trauma using a case-control study design. METHODS The medical records-linkage system of the Rochester Epidemiology Project was used to identify 196 subjects who developed PD in Olmsted County, MN, from 1976 through 1995. Each incident case was matched by age (+/-1 year) and sex to a(More)
BACKGROUND Microsatellite instability (MSI) and allelic imbalance involving chromosome arms 5q, 8p, 17p, and 18q are genetic alterations commonly found in colorectal cancer. We investigated whether the presence or absence of these genetic alterations would allow stratification of patients with Astler-Coller stage B2 or C colorectal cancer into favorable and(More)
Continuous enrichment of an arctic river with only 10 parts per billion phosphate-phosphorus caused an immediate growth of attached algae for more than 10 kilometers downstream, showing that phosphorus alone limited photosynthesis. As a result of the increased photosynthesis, there was an increase in bacterial activity in films on rocks on the bottom of the(More)
[1] Flow-weighted dissolved organic carbon (DOC) concentrations and d 18 O values were determined from major arctic rivers, specifically the Ob, Yenisey, Lena, Kolyma, Mackenzie, and Yukon during 2003–2004. These data were considered in conjunction with marine data for DOC, d 18 O values, nutrients, salinity, and fluorometric indicators of DOC obtained(More)
OBJECTIVE To study the association of PD with preceding smoking, alcohol, and coffee consumption using a case-control design. METHODS The authors used the medical records linkage system of the Rochester Epidemiology Project to identify 196 subjects who developed PD in Olmsted County, MN, during the years 1976 to 1995. Each incident case was matched by age(More)
OBJECTIVE To investigate the association of Parkinson disease (PD) with education and occupations using a case-control study design. METHODS The authors used the medical records-linkage system of the Rochester Epidemiology Project to identify all subjects who developed PD in Olmsted County, MN, from 1976 through 1995. Each incident case was matched by age(More)
The authors studied the association of markers of inflammation with the later development of Parkinson disease (PD) using a case-control design (196 cases and 196 matched controls). The frequency of diseases of immediate-type hypersensitivity was significantly higher in cases than controls. In addition, cases used anti-inflammatory agents less frequently(More)
A study of effects of terrestrial biota on the amount of carbon dioxide in the atmosphere suggests that the global net release of carbon due to forest clearing between 1860 and 1980 was between 135 x 10(15) and 228 x 10(15) grams. Between 1.8 x 10(15) and 4.7 x 10(15) grams of carbon were released in 1980, of which nearly 80 percent was due to(More)