A series of pairs of acoustic emission (AE) waveforms taken from either a closely spaced pair (64 mm) or a widely spaced pair (410 mm) of AE sensors mounted on a spherical graphite/epoxy pressure ...vessel of 260 mm outside diameter were examined. The waveforms from the small (6.3 mm diameter) aperture non-resonant sensors bandpassed from 85-325 kHz were recorded simultaneously on a 12-bit waveform recorder. Changes due to wave propagation in the typical AE hit characteristics (peak amplitude, duration, energy, spectrum, etc.) were correlated with distances from source to sensors and physical principles of wave propagation. Based upon the results, implications for AE monitoring and future AE studies of large fiber/polymer composite structures are presented. Also, AE source location in conjuction with a model for localized failure of a large aerospace type fiber/polymer composite structure was considered. Large changes in typical AE hit parameters were observed, particularly in the first 60 mm of propagation. These results bring into question typical approaches that have been developed for source identification and assessment of source significance in small test specimens. Large changes in arrival times of the same event at separate sensors were observed as a function of the system threshold setting. Possible approaches to overcome arrival time deficiencies as well as suggestions for future studies are presented.
The study purposes were to examine: (a) the determinants of exercise intention and past exercise behavior (PEB) using the theories of reasoned action and planned behavior, and (b) the moderating ...influences of sex and exercise group (meeting or not meeting exercise guidelines). Participants (n = 676 adolescents) completed self-reported measures of their exercise attitude, subjective norm, perceived behavioral control (PBC), intention, and PEB. We found that attitude, subjective norm, and PBC explained 55% of the variance in intention, and intention and PBC explained 51% of the variance in PEB. While we found sex and exercise group differences across the study measures, we did not find evidence of significant moderation. Thus, the theory constructs predicted intention and PEB similarly across sex and exercise groups.
OBJECTIVE: To assess the effect of providing structured information about the benefits and harms of mammography in differing frames on women's perceptions of screening.
DESIGN: Randomized control ...trial.
SETTING: General internal medicine academic practice.
PARTICIPANTS: One hundred seventy‐nine women aged 35 through 49.
INTERVENTION: Women received 1 of 3 5‐minute videos about the benefits and harms of screening mammography in women aged 40 to 49. These videos differed only in the way the probabilities of potential outcomes were framed (positive, neutral, or negative).
MEASUREMENTS AND MAIN RESULTS: We measured the change in accurate responses to questions about potential benefits and harms of mammography, and the change in the proportion of participants who perceived that the benefits of mammography were more important than the harms. Before seeing the videos, women's knowledge about the benefits and harms of mammography was inaccurate (82% responded incorrectly to all 3 knowledge questions). After seeing the videos, the proportion that answered correctly increased by 52%, 43%, and 30% for the 3 knowledge questions, respectively, but there were no differences between video frames. At baseline, most women thought the benefits of mammography outweighed the harms (79% positive frame, 80% neutral frame, and 85% negative frame). After the videos, these proportions were similar among the 3 groups (84%, 81%, 83%, P = .93).
CONCLUSIONS: Women improved the accuracy of their responses to questions about the benefits and harms of mammography after seeing the videos, but this change was not affected by the framing of information. Women strongly perceived that the benefits of mammography outweighed the harms, and providing accurate information had no effect on these perceptions, regardless of how it was framed.
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