We present microlensing events in the 2015 Korea Microlensing Telescope Network (KMTNet) data and our procedure for identifying these events. In particular, candidates were detected with a novel ..."completed-event" microlensing event-finder algorithm. The algorithm works by making linear fits to a grid of point-lens microlensing models. This approach is rendered computationally efficient by restricting u0 to just two values (0 and 1), which we show is quite adequate. The implementation presented here is specifically tailored to the commission-year character of the 2015 data, but the algorithm is quite general and has already been applied to a completely different (non-KMTNet) data set. We outline expected improvements for 2016 and future KMTNet data. The light curves of the 660 "clear microlensing" and 182 "possible microlensing" events that were found in 2015 are presented along with our policy for their public release.
We report the discovery of a giant planet in the OGLE-2017-BLG-1522 microlensing event. The planetary perturbations were clearly identified by high-cadence survey experiments despite the relatively ...short event timescale of tE ∼ 7.5 days. The Einstein radius is unusually small, θE = 0.065 mas, implying that the lens system either has very low mass or lies much closer to the microlensed source than the Sun, or both. A Bayesian analysis yields component masses and source-lens distance , implying that this is a brown-dwarf/Jupiter system that probably lies in the Galactic bulge, a location that is also consistent with the relatively low lens-source relative proper motion = 3.2 0.5 mas yr−1. The projected companion-host separation is , indicating that the planet is placed beyond the snow line of the host, i.e., asl ∼ 0.12 au. Planet formation scenarios combined with the small companion-host mass ratio q ∼ 0.016 and separation suggest that the companion could be the first discovery of a giant planet that formed in a protoplanetary disk around a brown-dwarf host.
Current microlensing surveys are sensitive to free-floating planets down to Earth-mass objects. All published microlensing events attributed to unbound planets were identified based on their short ...timescale (below two days), but lacked an angular Einstein radius measurement (and hence lacked a significant constraint on the lens mass). Here, we present the discovery of a Neptune-mass free-floating planet candidate in the ultrashort (tE = 0.320 0.003 days) microlensing event OGLE-2016-BLG-1540. The event exhibited strong finite-source effects, which allowed us to measure its angular Einstein radius of θE = 9.2 0.5 as. There remains, however, a degeneracy between the lens mass and distance. The combination of the source proper motion and source-lens relative proper motion measurements favors a Neptune-mass lens located in the Galactic disk. However, we cannot rule out that the lens is a Saturn-mass object belonging to the bulge population. We exclude stellar companions up to ∼15 au.
We analyze an ensemble of microlensing events from the 2015 Spitzer microlensing campaign, all of which were densely monitored by ground-based high-cadence survey teams. The simultaneous observations ...from Spitzer and the ground yield measurements of the microlensing parallax vector , from which compact constraints on the microlens properties are derived, including 25% uncertainties on the lens mass and distance. With the current sample, we demonstrate that the majority of microlenses are indeed in the mass range of M dwarfs. The planet sensitivities of all 41 events in the sample are calculated, from which we provide constraints on the planet distribution function. In particular, assuming a planet distribution function that is uniform in , where q is the planet-to-star mass ratio, we find a 95% upper limit on the fraction of stars that host typical microlensing planets of 49%, which is consistent with previous studies. Based on this planet-free sample, we develop the methodology to statistically study the Galactic distribution of planets using microlensing parallax measurements. Under the assumption that the planet distributions are the same in the bulge as in the disk, we predict that ∼1/3 of all planet detections from the microlensing campaigns with Spitzer should be in the bulge. This prediction will be tested with a much larger sample, and deviations from it can be used to constrain the abundance of planets in the bulge relative to the disk.
We present microlensing planet OGLE-2017-BLG-0173Lb, with planet-host mass ratio of either or , the lowest or among the lowest ever detected. The planetary perturbation is strongly detected, Δχ2 ∼ ...10000, because it arises from a bright (therefore, large) source passing over and enveloping the planetary caustic: a so-called "Hollywood" event. The factor ∼2.5 offset in q arises because of a previously unrecognized discrete degeneracy between Hollywood events in which the caustic is fully enveloped and those in which only one flank is enveloped, which we dub "Cannae" and "von Schlieffen," respectively. This degeneracy is "accidental" in that it arises from gaps in the data. Nevertheless, the fact that it appears in a Δχ2 = 10000 planetary anomaly is striking. We present a simple formalism to estimate the sensitivity of other Hollywood events to planets and show that they can lead to detections close to, but perhaps not quite reaching, the Earth/Sun mass ratio of . This formalism also enables an analytic understanding of the factor ∼2.5 offset in q between the Cannae and von Schlieffen solutions. The Bayesian estimates for the host mass, system distance, and planet-host projected separation are , , and , respectively. The two estimates of the planet mass are and . The measured lens-source relative proper motion will permit imaging of the lens in about 15 years or at first light on adaptive-optics imagers on next-generation telescopes. These will allow one to measure the host mass but probably will not be able to resolve the planet-host mass-ratio degeneracy.
Adjuvant chemotherapy and chemoradiotherapy are some of the standards of care for gastric cancer (GC). The Adjuvant chemoRadioTherapy In Stomach Tumors (ARTIST) 2 trial compares two adjuvant ...chemotherapy regimens and chemoradiotherapy in patients with D2-resected, stage II or III, node-positive GC.
The ARTIST 2 compared, in a 1:1:1 ratio, three adjuvant regimens: oral S-1 (40-60 mg twice daily 4 weeks on/2 weeks off) for 1 year, S-1 (2 weeks on/1 week off) plus oxaliplatin 130 mg/m2 every 3 weeks (SOX) for 6 months, and SOX plus chemoradiotherapy 45 Gy (SOXRT). Randomization was stratified according to surgery type (total or subtotal gastrectomy), pathologic stage (II or III), and Lauren histologic classification (diffuse or intestinal/mixed). The primary endpoint was disease-free survival (DFS) at 3 years; a reduction of 33% in the hazard ratio (HR) for DFS with SOX or SOXRT, when compared with S-1, was considered clinically meaningful. The trial is registered at clinicaltrials.gov (NCT0176146).
A total of 546 patients were recruited between February 2013 and January 2018 with 182, 181, and 183 patients in the S-1, SOX, and SOXRT arms, respectively. Median follow-up period was 47 months, with 178 DFS events observed. Estimated 3-year DFS rates were 64.8%, 74.3%, and 72.8% in the S-1, SOX, and SOXRT arms, respectively. HR for DFS in the control arm (S-1) was shorter than that in the SOX and SOXRT arms: S-1 versus SOX, 0.692 (P = 0.042) and S-1 versus SOXRT, 0.724 (P = 0.074). No difference in DFS was found between SOX and SOXRT (HR 0.971; P = 0.879). Adverse events were as anticipated in each arm, and were generally well-tolerated and manageable.
In patients with curatively D2-resected, stage II/III, node-positive GC, adjuvant SOX or SOXRT was effective in prolonging DFS, when compared with S-1 monotherapy. The addition of radiotherapy to SOX did not significantly reduce the rate of recurrence after D2 gastrectomy.
•In patients with curatively D2-resected, stage II/III, node-positive GC, adjuvant SOX or SOXRT was effective in prolonging DFS, when compared with S-1 monotherapy.•The addition of radiotherapy to chemotherapy did not significantly reduce the rate of recurrence after D2 gastrectomy.•DFS between patients treated with adjuvant chemotherapy and chemoradiotherapy was similar across all subgroups, including Lauren classification.
We combine Spitzer and ground-based Korea Microlensing Telescope Network microlensing observations to identify and precisely measure an Earth-mass ( ) planet OGLE-2016-BLG-1195Lb at orbiting a ...ultracool dwarf. This is the lowest-mass microlensing planet to date. At kpc, it is the third consecutive case among the Spitzer "Galactic distribution" planets toward the Galactic bulge that lies in the Galactic disk as opposed to the bulge itself, hinting at a skewed distribution of planets. Together with previous microlensing discoveries, the seven Earth-size planets orbiting the ultracool dwarf TRAPPIST-1, and the detection of disks around young brown dwarfs, OGLE-2016-BLG-1195Lb suggests that such planets might be common around ultracool dwarfs. It therefore sheds light on the formation of both ultracool dwarfs and planetary systems at the limit of low-mass protoplanetary disks.
We report two microlensing events, KMT-2017-BLG-1038 and KMT-2017-BLG-1146, that are caused by planetary systems. These events were discovered by Korea Microlensing Telescope Network survey ...observations from the 2017 bulge season. The discovered systems consist of a planet and host star with mass ratios of and , respectively. Based on a Bayesian analysis assuming a Galactic model without stellar remnant hosts, we find that the planet KMT-2017-BLG-1038Lb is a super-Jupiter-mass planet ( ) orbiting a mid-M dwarf host ( ) that is located at kpc toward the Galactic bulge. The other planet, KMT-2017-BLG-1146Lb, is a sub-Jupiter-mass planet ( ) orbiting a mid-M dwarf host ( ) at a distance of kpc toward the Galactic bulge. Both are potentially gaseous planets that are beyond their hosts' snow lines. These typical microlensing planets will be routinely discovered by second-generation microlensing surveys, rapidly increasing the number of detections.
PDF
