Evidence of structural discontinuities in the inner core of red-giant stars.

Red giants are stars in the late stages of stellar evolution. Because they have exhausted the supply of hydrogen in their core, they burn the hydrogen in the surrounding shell . Once the helium in the core starts fusing, the star enters the clump phase, which is identified as a striking feature in the color-magnitude diagram. Since clump stars share similar observational properties, they are heavily used in astrophysical studies, as probes of distance, extinction through the galaxy, galaxy density, and stellar chemical evolution. In this work, we perform the detailed observational characterization of the deepest layers of clump stars using asteroseismic data from Kepler. We find evidence for large core structural discontinuities in about 6.7% of the stars in our sample, implying that the region of mixing beyond the convective core boundary has a radiative thermal stratification. These stars are otherwise similar to the remaining stars in our sample, which may indicate that the building of the discontinuities is an intermittent phenomenon.

Risk of bacterial exposure to the endoscopist's face during endoscopy.

BACKGROUND AND AIMS: Nonuniversal use of facial protection during endoscopy may place endoscopists at risk of exposure to blood and body fluids; however, the frequency of exposure is unknown. METHODS: A prospective 6-month study of 4 gastroenterologists using a face shield during endoscopy was undertaken. The face shield was swabbed in a standardized fashion before and at the end of the session. Controls included pre- and post-swabs of face shields placed on the (1) endoscopy suite wall, (2) remote patient intake bay wall, and (3) after deliberate contamination with a colonoscope immediately after colonoscopy. The swabs were cultured for 48 hours, and growth was reported as no growth or by number of colony-forming units (CFUs). The groups were compared for +CFU rate and CFU number. RESULTS: A total of 1100 procedures were performed in 239 endoscopy sessions. The +CFU rate in the pre-endoscopy groups (2%-4.8%, not significant) was significantly lower than the postendoscopist face shield (45.8%, P < .001) and endoscopy suite wall groups (21.4%, P < .001), respectively. Using a cut-off of >15 CFUs as an indicator of definite exposure, the occurrence rate was 5.6 per 100 half days of endoscopy to the endoscopist's face and 3.4 per 100 half days of endoscopy 6 feet away. CONCLUSIONS: This is the first study to quantify the rate of unrecognized exposure to the endoscopist's face to potentially infectious biologic samples during endoscopy (5.6/100 days of endoscopy). This exposure may result in transmission of infectious diseases. As such, we recommend the use of universal facial protection during GI endoscopy.