PubMed Health⌕ Search

Biomedical subjects

S Nutter

Publications and source records attributed to S Nutter.

11 recordsLinked to original sources
PubMed2004

New measurement of the cosmic-ray positron fraction from 5 to 15 GeV.

We present a new measurement of the cosmic-ray positron fraction at energies between 5 and 15 GeV with the balloon-borne HEAT-pbar instrument in the spring of 2000. The data presented here are compatible with our previous measurements, obtained with a different instrument. The combined data from the three HEAT flights indicate a small positron flux of nonstandard origin above 5 GeV. We compare the new measurement with earlier data obtained with the HEAT-e(+/-) instrument, during the opposite epoch of the solar cycle, and conclude that our measurements do not support predictions of charge sign dependent solar modulation of the positron abundance at 5 GeV.

Journal Article↗
PubMed2001

Measurement of the cosmic-ray antiproton-to-proton abundance ratio between 4 and 50 GeV.

We present a new measurement of the antiproton-to-proton abundance ratio, pbar/p, in the cosmic radiation. The HEAT-pbar instrument, a balloon borne magnet spectrometer with precise rigidity and multiple energy loss measurement capability, was flown successfully in Spring 2000, at an average atmospheric depth of 7.2 g/cm(2). A total of 71 antiprotons were identified above the vertical geomagnetic cutoff rigidity of 4.2 GV. The highest measured proton energy was 81 GeV. We find that the pbar/p abundance ratio agrees with that expected from a purely secondary origin of antiprotons produced by primary protons with a standard soft energy spectrum.

Journal Article↗
PubMed1978

Colonic bacterial activity, biliary cholesterol saturation, and pathogenesis of gallstones.

The relation between colonic bacterial metabolites in bile and saturation of bile with cholesterol was investigated. Eleven healthy men ingested metronidazole (2 g daily) for 10 days to inhibit anaerobic bacterial activity. Bile composition was determined in fasting samples aspirated from the duodenum before metronidazole was given, at the end of 10 days on metronidazole, and a month after the drug was discontinued. Bile cholesterol saturation fell in ten of the eleven subjects from a mean of 1.00 to 0.83 and rose in all eleven after the drug was stopped. At the same time the proportion of deoxycholate in bile acid decreased from a mean of 24% to 7%, returning to 22% of the total a month after metronidazole had been stopped, and the proportion of chenodeoxycholate changed significantly from 33% to 46% and back to 33%. There was little change in cholate concentrations. Deoxycholate is formed exclusively by bacterial action in the colon. Its administration increases cholesterol saturation of bile, while chenodeoxycholate reduces it. These results suggest that colonic function is important in regulating bile composition. Dietary measures which reduce the return of newly formed deoxycholate from the colon to the bile reduce cholesterol saturation and so are likely to reduce the risk of gallstones.

Adult↗
PubMed1971

Xylose test: effect of aspirin and indomethacin.

The xylose test was used to assess the effect of drugs on intestinal absorption. Both aspirin and indomethacin reduced the urinary output of xylose. By giving xylose intravenously as well as orally it was found that aspirin had a parenteral effect, probably impairing renal function, whereas indomethacin depressed intestinal absorption.

Administration, Oral↗
PubMed1970

The influence of sex, body weight, and renal function on the xylose test.

A low excretion of xylose may be due to malabsorption, renal disease, or old age. Malabsorption can be distinguished from other causes by performing a combined oral and intravenous test, the result being expressed as a fraction of these readings. Sex and body weight do not influence the xylose test.

Adolescent↗