ABSTRACT We find that significant incompleteness in stellar number counts results in a significant overestimate of the microlensing optical depth τ and event rate per star per year Γ toward the ...Galactic bulge from the first two years of the MOA-II survey. We find that the completeness in red clump giant (RCG) counts decreases proportional to the galactic latitude b, as , ranging between 1 and 0.7 at . The previous measurements using all sources by difference image analysis (DIA) by MACHO and MOA-I suffer the same bias. On the other hand, the measurements using an RCG sample by OGLE-II, MACHO, and EROS were free from this bias because they selected only the events associated with the resolved stars. Thus, the incompleteness both in the number of events and stellar number count cancel out. We estimate τ and Γ by correcting this incompleteness. In the central fields with , we find star−1 yr−1 and for the 427 events with days using all sources brighter than mag. Our revised all-source τ measurements are about 2 smaller than the other all-source measurements and are consistent with the RCG measurements within 1 . We conclude that the long-standing problem on discrepancy between the high τ with all-source samples by DIA and low τ with RCG samples can probably be explained by the incompleteness of the stellar number count. A model fit to these measurements predicts star−1 yr−1 at and for sources with , where the future space mission, Wide Field Infrared Space Telescope, will observe.
ABSTRACT We report the results of the statistical analysis of planetary signals discovered in MOA-II microlensing survey alert system events from 2007 to 2012. We determine the survey sensitivity as ...a function of planet-star mass ratio, q, and projected planet-star separation, s, in Einstein radius units. We find that the mass-ratio function is not a single power law, but has a change in slope at q ∼ 10−4, corresponding to ∼20 M⊕ for the median host-star mass of ∼0.6 . We find significant planetary signals in 23 of the 1474 alert events that are well-characterized by the MOA-II survey data alone. Data from other groups are used only to characterize planetary signals that have been identified in the MOA data alone. The distribution of mass ratios and separations of the planets found in our sample are well fit by a broken power-law model of the form for q > qbr and for q < qbr, where qbr is the mass ratio of the break. We also combine this analysis with the previous analyses of Gould et al. and Cassan et al., bringing the total sample to 30 planets. This combined analysis yields , n = −0.93 0.13, , and for qbr 1.7 × 10−4. The unbroken power-law model is disfavored with a p-value of 0.0022, which corresponds to a Bayes factor of 27 favoring the broken power-law model. These results imply that cold Neptunes are likely to be the most common type of planets beyond the snow line.
We present a statistical analysis of the first four seasons from a second-generation microlensing survey for extrasolar planets, consisting of near-continuous time coverage of 8 deg to the 2nd power ...of the Galactic bulge by the Optical Gravitational Lens Experiment (OGLE), Microlensing Observations in Astrophysics (MOA), and Wise microlensing surveys. During this period, 224 microlensing events were observed by all three groups. Over 12% of the events showed a deviation from single-lens microlensing, and for approx. 1/3 of those the anomaly is likely caused by a planetary companion. For each of the 224 events, we have performed numerical ray-tracing simulations to calculate the detection efficiency of possible companions as a function of companion-to-host mass ratio and separation. Accounting for the detection efficiency, we find that 55 +34 -22%of microlensed stars host a snowline planet. Moreover, we find that Neptune-mass planets are approx.10 times more common than Jupiter-mass planets. The companion-to-host mass-ratio distribution shows a deficit at q approx. 10 (exp -2), separating the distribution into two companion populations, analogous to the stellar-companion and planet populations, seen in radial-velocity surveys around solar-like stars. Our survey, however, which probes mainly lower mass stars, suggests a minimum in the distribution in the super-Jupiter mass range, and a relatively high occurrence of brown-dwarf companions.
Abstract
We report discovery of the lowest mass ratio exoplanet to be found by the microlensing method in the light curve of the event OGLE 2016–BLG–1195. This planet revealed itself as a small ...deviation from a microlensing single lens profile from an examination of the survey data. The duration of the planetary signal is ∼2.5 h. The measured ratio of the planet mass to its host star is q = 4.2 ± 0.7 × 10−5. We further estimate that the lens system is likely to comprise a cold ∼3 Earth mass planet in an ∼2 au wide orbit around a 0.2 Solar mass star at an overall distance of 7.1 kpc.
•A model that considers PS to describe pedestrian movement on stairs is proposed.•The personal space (PS) is composed of four arcs which belong to four circles.•Dynamic characteristics of PS and its ...specifications were obtained from experiment.•A simulation was hold under the obtained parameters.•Fundamental diagram according to different na/nb was analysed.
This paper presents an enhanced model that considers the specifications of personal space to describe uni- and bi-directional pedestrian movement on stairs. The shape of the personal space of each pedestrian is regarded as an oval shape, which is composed of four arcs, to precisely quantify movements. Specific models that facilitate the simulation of movement include adjustments to individual speeds based on the proximity of other members, conflict avoidance, overtaking, and direction finding. By implementing these parameters in the simulation, basic data concerning these movement behaviours were collected from the experiment, which was carried out at one a Shanghai subway station. Twenty-four young college students participated in this experiment. Numerical simulation results for a stochastic case under those parameters were obtained. The fundamental diagrams and moving behaviours according to different proportions of ascending and descending pedestrians are analysed and discussed. The results indicate that the simulation platform for personal space can serve as a useful tool to evaluate pedestrian movement on stairs.
Based on high-resolution spectra obtained during gravitational microlensing events we present a detailed elemental abundance analysis of 32 dwarf and subgiant stars in the Galactic bulge. Combined ...with the sample of 26 stars from the previous papers in this series, we now have 58 microlensed bulge dwarfs and subgiants that have been homogeneously analysed. The results from the microlensed bulge dwarf stars in combination with other findings in the literature, in particular the evidence that the bulge has cylindrical rotation, indicate that the Milky Way could be an almost pure disk galaxy. The bulge would then just be a conglomerate of the other Galactic stellar populations, residing together in the central parts of the Galaxy, influenced by the Galactic bar.
The increasing acceptance of ready to eat food generates demand on development of active and intelligent food packaging material. Even though many polymers have been used for the packaging, they have ...limitations for broad applications. Among the various polymers, Poly Vinyl Alcohol is a promising film forming polymer with highly flexible, emulsifying and adhesive properties. A variety of nano-fabrication techniques have already been reported to improve the mechanical and antimicrobial properties of PVA to exploit its wider applications. In the present study, starch-PVA based composite films incorporated with zinc oxide nanoparticles and phytochemicals were prepared by solvent casting technique. The films were characterized by XRD, FT-IR, UV–Vis spectrometry and SEM. The developed nanocomposite films were demonstrated to have enhanced water barrier, mechanical and antimicrobial properties. The unique features of the nanocomposite with its pH indication property demonstrated in the study indicate its potential usage in food packaging applications.
•pH sensing antimicrobial wraps were prepared and characterized.•Films were found to be water resistant with excellent UV-light barrier properties.•Microbial barrier ability also makes it suitable for packaging foods.
ADCs may help distinguish benign from malignant head and neck diseases. We sought to evaluate the effectiveness of ADC for differentiating between carcinomas and lymphomas of the nasopharynx and ...oropharynx.
We retrospectively compared the ADCs between 24 histologically proved lymphomas and 32 carcinomas, including 8 NPCs and 7 lymphomas of the nasopharynx, and 24 SCCs and 17 lymphomas of the oropharynx. ADCs were determined on tumor-by-tumor (overall ADCs) and pixel-by-pixel (ADC mapping) bases by using 2 b-values (500 and 1000 s/mm(2)).
Lymphomas and oropharyngeal SCCs had unique histologic features in terms of keratinization, cell attenuation, stromal areas, and necrosis and had distinctive ADCs (0.503 ± 0.099 × 10(-3) mm(2)/s for lymphomas and 0.842 ± 0.164 × 10(-3) mm(2)/s for SCCs). However, NPCs and lymphomas were similar in terms of these histologic features, exhibiting comparable ADCs (0.567 ± 0.057 × 10(-3) mm(2)/s for NPCs and 0.528 ± 0.094 × 10(-3) mm(2)/s for lymphomas). Poorly and moderately differentiated SCCs with homogeneous T2 signals were indistinguishable from lymphomas on conventional MR images; however, ADCs of these SCC subtypes were significantly larger than those of lymphomas. ADC mapping profiles with respect to percentage of tumor areas of extremely low, intermediate, and high ADC levels were well-correlated with the histologic features of lymphomas, NPCs, and different types of SCCs.
The effectiveness of ADC-based differentiation between lymphomas and carcinomas of the nasopharynx and oropharynx depends on their histologic characteristics.
We present measurements of the microlensing optical depth and event rate toward the Galactic Bulge (GB) based on two years of the MOA-II survey. Our event rate and optical depth analysis uses 474 ...events with well-defined microlensing parameters. We find that the event rate is maximized at low latitudes and a longitude of l approximately 1degrees. The main difference is the lack of long duration events in the RCG sample due to a known selection effect. Our results are consistent with previous optical depth measurements, but they are somewhat lower than previous all-source measurements, and slightly higher than previous RCG optical depth measurements. This suggests that the previously observed difference in optical depth measurements between all-source and RCG samples may largely be due to statistical fluctuations. These event rate measurements toward the central GB are necessary to predict the microlensing event rate and to optimize the survey fields in future space missions such as Wide Field Infrared Space Telescope.
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