The Carnegie-Chicago Hubble Program: Discovery of the Most Distant Ultra-faint Dwarf Galaxy in the Local Universe

Ultra-faint dwarf galaxies (UFDs) are the faintest known galaxies and due to their incredibly low surface brightness, it is difficult to find them beyond the Local Group. We report a serendipitous discovery of an UFD, Fornax UFD1, in the outskirts of NGC 1316, a giant galaxy in the Fornax cluster. The new galaxy is located at a projected radius of 55 kpc in the south-east of NGC 1316. This UFD is found as a small group of resolved stars in the Hubble Space Telescope images of a halo field of NGC 1316, obtained as part of the Carnegie-Chicago Hubble Program. Resolved stars in this galaxy are consistent with being mostly metal-poor red giant branch (RGB) stars. Applying the tip of the RGB method to the mean magnitude of the two brightest RGB stars, we estimate the distance to this galaxy, 19.0 +- 1.3 Mpc. Fornax UFD1 is probably a member of the Fornax cluster. The color-magnitude diagram of these stars is matched by a 12 Gyr isochrone with low metallicity ([Fe/H] ~ -2.4). Total magnitude and effective radius of Fornax UFD1 are Mv ~ -7.6 +- 0.2 mag and r_eff = 146 +- 9 pc, which are similar to those of Virgo UFD1 that was discovered recently in the intracluster field of Virgo by Jang & Lee (2014).Fornax UFD1 is the most distant known UFD that is confirmed by resolved stars. This indicates that UFDs are ubiquitous and that more UFDs remain to be discovered in the Fornax cluster.Comment: 6 pages, 4 figures, 1 table, accepted for publication in ApJ Letter

The role of additional silane coupling agent treatment in oxygen plasma-treated UHMPE fiber/ vinylester composites

Abstract—Ultra-high modulus polyethylene (UHMPE) ber was treated with oxygen plasma and a silane coupling agent in order to improve the interfacial adhesion between the UHMPE ber and vinylester resin. The oxygen plasma and ° -methylmethacryloxypropyltrimethoxysilane (° -MPS)- treated UHMPE ber/vinylester composites showed a slightly higher interlaminar shear strength than the oxygen plasma-treatedUHMPE ber/ vinylester composites. The interfacial adhesion of the oxygen plasma-treatedUHMPE ber/ vinylester composites in this study is mainly due to mechanical interlocking between the micropits formed by the oxygen plasma treatment and the vinylester resin. The ° -MPS molecules adsorbed onto the UHMPE ber surface neither affected the morphology of the UHMPE ber surface, nor reduced the extent of mechanical interlocking. The improved interfacial adhesion by the ° -MPS treatment is due to enhanced wettability and chemical interaction through the chemically adsorbed ° -MPS molecules, as detected by Fourier-transforminfrared(FT-IR) spectroscopy. The ° -MPS molecules adsorbed onto the ultra-high molecular weight polyethylene (UHMWPE) plate surface also reduced the aging effect of the oxygen plasma-treated UHMWPE surface

Engaging social activities prevent stroke and myocardial infraction by raising awareness of warning symptoms: A cross-sectional survey study

BackgroundStroke and myocardial infarction (MI) are medical emergencies, and early treatment within the golden hour is crucial for good prognosis. Adequate knowledge about the warning symptoms can shorten the onset-to-door time. Various factors affect the level of awareness, including social activity. This study aimed to determine if engaging in social activity is associated with the awareness of the warning symptoms of stroke and MI.MethodsThis cross-sectional study analyzed 451,793 participants from the 2017 and 2019 Korea Community Health Survey. Based on five questions for each of stroke and MI symptoms, participants were divided into an awareness group (replied “Yes” to all five questions) and unawareness group. Engagement in social activities (i.e., religious, friendship, leisure, and volunteer activity) was evaluated through a questionnaire. Multiple logistic regression analysis was performed to evaluate the relation between social activity and awareness of warning symptoms.ResultsOverall, 52.6% participants were aware of the warning symptoms of stroke, and 45.8% of MI. Regular engagement in at least one social activity, particularly friendship or volunteer activity, was associated with better awareness of the warning symptoms, both stroke (OR: 1.21, 95% CI: 1.20–1.23) and MI (OR: 1.22, 95% CI: 1.20–1.24). Additionally, more diverse types of social activities were associated with higher levels of awareness. Relationship between social activity and awareness showed positive association with participants older than 60 years, rural residents, or with low socioeconomic status.ConclusionEngagement in social activity was significantly associated with better knowledge about the warning symptoms of stroke and MI. For early hospital treatment after symptom onset, participation in social activities could be beneficial