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FREE-FLOATING PLANETS, THE EINSTEIN DESERT, AND 'OUMUAMUA
Gould, Andrew,Jung, Youn Kil,Hwang, Kyu-Ha,Dong, Subo,Albrow, Michael D.,Chung, Sun-Ju,Han, Cheongho,Ryu, Yoon-Hyun,Shin, In-Gu,Shvartzvald, Yossi,Yang, Hongjing,Yee, Jennifer C.,Zang, Weicheng,Cha, S The Korean Astronomical Society 2022 Journal of The Korean Astronomical Society Vol.55 No.5
We complete the survey for finite-source/point-lens (FSPL) giant-source events in 2016-2019 KMTNet microlensing data. The 30 FSPL events show a clear gap in Einstein radius, 9 𝜇as < 𝜃<sub>E</sub> < 26 𝜇as, which is consistent with the gap in Einstein timescales near t<sub>E</sub> ~ 0.5 days found by Mróz et al. (2017) in an independent sample of point-source/point-lens (PSPL) events. We demonstrate that the two surveys are consistent. We estimate that the 4 events below this gap are due to a power-law distribution of free-floating planet candidates (FFPs) dN<sub>FFP</sub>/d log M = (0.4 ± 0.2) (M/38 M<sub>⊕</sub>)<sup>-p</sup>/star, with 0.9 ≲ p ≲ 1.2. There are substantially more FFPs than known bound planets, implying that the bound planet power-law index 𝛾 = 0.6 is likely shaped by the ejection process at least as much as by formation. The mass density per decade of FFPs in the Solar neighborhood is of the same order as that of 'Oumuamua-like objects. In particular, if we assume that 'Oumuamua is part of the same process that ejected the FFPs to very wide or unbound orbits, the power-law index is p = 0.89 ± 0.06. If the Solar System's endowment of Neptune-mass objects in Neptune-like orbits is typical, which is consistent with the results of Poleski et al. (2021), then these could account for a substantial fraction of the FFPs in the Neptune-mass range.
Coronary Artery Dose-Volume Parameters Predict Risk of Calcification After Radiation Therapy
Sarah A. Milgrom,Bibin Varghese,Gregory W. Gladish,Andrew D. Choi,Wenli Dong,Zarana S. Patel,Caroline C. Chung,Arvind Rao,Chelsea C. Pinnix,Jillian R. Gunther,Bouthaina S. Dabaja,Steven H. Lin,Karen E 한국심초음파학회 2019 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.27 No.4
BACKGROUND: Radiation exposure increases the risk of coronary artery disease (CAD). We explored the association of CAD with coronary artery dose-volume parameters in patients treated with 3D-planned radiation therapy (RT). METHODS: Patients who received thoracic RT and were evaluated by cardiac computed tomography ≥ 1 year later were included. Demographic data and cardiac risk factors were retrospectively collected. Dosimetric data (mean heart dose, dmax, dmean, V50 - V5) were collected for the whole heart and for each coronary artery. A coronary artery calcium (CAC) Agatston score was calculated on a per-coronary basis and as a total score. Multivariable generalized linear mixed models were generated. The predicted probabilities were used for receiver operating characteristic analyses. RESULTS: Twenty patients with a median age of 53 years at the time of RT were included. Nine patients (45%) had ≥ 3/6 conventional cardiac risk factors. Patients received RT for breast cancer (10, 50%), lung cancer (6, 30%), or lymphoma/myeloma (4, 20%) with a median dose of 60 Gy. CAC scans were performed a median of 32 months after RT. CAC score was significantly associated with radiation dose and presence of diabetes. In a multivariable model adjusted for diabetes, segmental coronary artery dosimetric parameters (dmax, dmean, V50, V40 V30, V20, V10, and V5) were significantly associated with CAC score > 0. V50 had the highest area under the ROC curve (0.89, 95% confidence interval, 0.80-0.97). CONCLUSIONS: Coronary artery radiation exposure is strongly correlated with subsequent segmental CAC score. Coronary calcification may occur soon after RT and in individuals with conventional cardiac risk factors.