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41.
The Youth Risk Behavior Surveillance System (YRBSS) monitors priority health-risk behaviors among US high school students. To better understand the ramifications of changing the YRBSS from paper-and-pencil to Web administration, in 2008 the Centers for Disease Control and Prevention conducted a study comparing these two modes of administration. Eighty-five schools in 15 states agreed to participate in the study. Within each participating school, four classrooms of students in grades 9 or 10 were randomly assigned to complete the Youth Risk Behavior Survey questionnaire in one of four conditions (in-class paper-and-pencil, in-class Web without programmed skip patterns, in-class Web with programmed skip patterns, and “on your own” Web without programmed skip patterns). Findings included less missing data for the paper-and-pencil condition (1.5% vs. 5.3%, 4.4%, 6.4%; p < .001), less perceived privacy and anonymity among respondents for the in-class Web conditions, and a lower response rate for the “on your own” Web condition than for in-class administration by either mode (28.0% vs. 91.2%, 90.1%, 91.4%; p < .001). Although Web administration might be useful for some surveys, these findings do not favor the use of a Web survey for the YRBSS.  相似文献   
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DP Warren  JT Chan 《Canadian Metallurgical Quarterly》1997,45(2):134-40, 142; quiz 145-6
Fluoride's role in decreasing dental caries has been recognized for decades. The professional fluoride treatment has recently been augmented with home-use fluoride products. The introduction of many attractive products makes it difficult for dental professionals to know which are effective. Both professional and home-use products are described, as are proven techniques for their use. Recognition of fluoride toxicity, and its prevention and treatment, are also discussed.  相似文献   
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An ethylene–ethyl acrylate–maleic anhydride copolymer (EEAMA) is grafted with aminopropyl polydimethylsiloxane (PDMS) via melt reactive mixing at 140°C. The materials produced split into two components based on their solubility in acetone. The acetone soluble material is highly enriched in PDMS, whereas the insoluble material contains levels of PDMS that are lower than the proportions added to the reaction mixture. It was found that for all reaction mixtures the PDMS content in the acetone insoluble solids increases with mixing time. Molecular weight distributions of materials become narrower as the amount of PDMS increases. Rheological testing shows that the level of PDMS in the mixtures and the presence of the acetone soluble fractions give rise to significant changes in the complex viscosity and elastic moduli for the polymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4230–4237, 2006  相似文献   
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Most patients in acute myocardial infarction (AMI) undergo emergent coronary angiography (CAG). However, when to analyze lipoprotein profiles in AMI is not clear. To determine whether lipoprotein profiles change during catheterization, we measured serum lipid and apolipoprotein concentrations in 65 patients (51 men and 14 women) before and after catheterization. Heparin was injected at 50 units/kg for CAG and 200 units/kg for percutaneous transluminal coronary angioplasty (PTCA). We found that cholesterol and triglyceride decreased by 9.4% (P < 0.001) and 53.1% (P < 0.001), respectively, after catheterization. Apolipoproteins also decreased significantly. Variables decreased two to five times more after PTCA than after CAG. Lipoprotein lipase mass was higher after PTCA (267.8 +/- 135.3 micrograms/L) than after CAG (93.3 +/- 48.4 micrograms/L; P < 0.05). In conclusion, lipoprotein profiles change during catheterization. We recommend avoiding analysis of lipoprotein profiles after emergent CAG in AMI.  相似文献   
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All for one...     
McManus  John; Jennings  Neville 《ITNOW》2002,44(6):22-23
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Because knowledge has advanced in several fields related to the treatment of early breast cancer, revising the landmark 1992 standards for breast-conservation treatment by these four organizations is appropriate. The current report reviews and summarizes the literature and describes the selection and evaluation of patients, the technical aspects of surgical treatment and irradiation, follow-up care, and areas for further research.  相似文献   
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