7 research outputs found

    Intercomparisons of Nine Sky Brightness Detectors

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    Nine Sky Quality Meters (SQMs) have been intercompared during a night time measurement campaign held in the Netherlands in April 2011. Since then the nine SQMs have been distributed across the Netherlands and form the Dutch network for monitoring night sky brightness. The goal of the intercomparison was to infer mutual calibration factors and obtain insight into the variability of the SQMs under different meteorological situations. An ensemble average is built from the individual measurements and used as a reference to infer the mutual calibration factors. Data required additional synchronization prior to the calibration determination, because the effect of moving clouds combined with small misalignments emerges as time jitter in the measurements. Initial scatter of the individual instruments lies between ±14%. Individual night time sums range from −16% to +20%. Intercalibration reduces this to 0.5%, and −7% to +9%, respectively. During the campaign the smallest luminance measured was 0.657 ± 0.003 mcd/m2 on 12 April, and the largest value was 5.94 ± 0.03 mcd/m2 on 2 April. During both occurrences interfering circumstances like snow cover or moonlight were absent

    COX-2 polymorphisms -765G→C and -1195A→G and colorectal cancer risk

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    AIM: To determine the possible modulating effect of the COX-2 polymorphisms, -765G→C and -1195A→G, on the risk of colorectal cancer (CRC) in a Dutch population

    The stool antigen test for detection of Helicobacter pylori after eradication therapy

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    BACKGROUND: Current noninvasive tests to confirm the eradication of Helicobacter pylori must be performed 4 weeks or more after eradication therapy is completed. OBJECTIVE: To determine whether the stool antigen test, a relatively new noninvasive test for H. pylori, administered at various times after eradication therapy correctly identifies persons with persistent H. pylori infection. DESIGN: Prospective blinded study. SETTING: Six clinical centers in the United States and Europe. PATIENTS: 84 H. pylori --infected patients undergoing endoscopy for upper abdominal symptoms. MEASUREMENTS: At baseline and on day 35 after the completion of triple eradication therapy, all patients underwent endoscopy with histologic examination, rapid urease test and culture, urea breath test, and a stool antigen test. The stool antigen test was also performed on days 3, 7, 15, 21, 28, and 35 after completion of therapy. RESULTS: Compared with the gold-standard endoscopic tests on day 35 after antimicrobial therapy, the urea breath test had a sensitivity of 94% (95% CI, 71% to 100%) and a specificity of 100% (CI, 94% to 100%). The stool antigen test had a sensitivity of 94% (CI, 71% to 100%) and a specificity of 97% (CI, 89% to 100%). On day 7 after treatment, the stool antigen test was predictive of eradication (positive predictive value, 100% [CI, 69% to 100%]; negative predictive value, 91% [CI, 82% to 97%]). CONCLUSION: A positive result on the stool antigen test 7 days after completion of therapy identifies patients in whom eradication of H. pylori was unsuccessfu
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