Search

RI-RICH, a ring-imaging Cherenkov counter for radioactive ions, has been developed to measure the velocity of the ions at intermediate energies. Our RI-RICH system consists of six multi-anode photomultiplier tubes covered with 360-nm bandpass filters and a radiator made of quartz or BK7. For the primary 132Xe beam with a velocity of β = 0 . 712 , a velocity resolution of Δ β ∕ β = 4 . 9 × 1 0 − 4 (one standard deviation σ ) and a detection efficiency of more than 99.99% were achieved. For the secondary beams with Z = 44 – 55 and β ≃ 0 . 70 , we successfully performed particle identification using the B ρ - Δ E - β method. The velocity resolutions of RI-RICH for these nuclides were equivalent to a more than 6 σ separation for the mass number.

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$^2$ of the Galactic bulge by the OGLE, 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 $\sim$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 Neptunes-mass planets are $\sim10$ times more common than Jupiter-mass planets. The companion-to-host mass ratio distribution shows a deficit at $q\sim10^{-2}$, 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., Comment: 24 pages, 13 figures, 2 tables. 2016, MNRAS, 457, 4089

Charge changing cross sections (\(\sigma _{\text{CC}}\)) for ^40–48K and ^42–51Ca have been measured using BigRIPS at RIBF, RIKEN. The \(\sigma _{\text{CC}}\) obtained along the long isotopic chain of K and Ca revealed the fact that \(\sigma _{\text{CC}}\) have strong proton separation energy () dependence. The data are compared with the calculation based on the Glauber model and also with the proton evaporation model. It is found that the \(\sigma _{\text{CC}}\) data are well reproduced when the proton evaporation effect is taken into account.

Interaction cross sections for ^{42-51}Ca on a carbon target at 280 MeV/nucleon have been measured for the first time. The neutron number dependence of derived root-mean-square matter radii shows a significant increase beyond the neutron magic number N=28. Furthermore, this enhancement of matter radii is much larger than that of the previously measured charge radii, indicating a novel growth in neutron skin thickness. A simple examination based on the Fermi-type distribution, and mean field calculations point out that this anomalous enhancement of the nuclear size beyond N=28 results from an enlargement of the core by a sudden increase in the surface diffuseness of the neutron density distribution, which implies the swelling of the bare ^{48}Ca core in Ca isotopes beyond N=28.

We present the analysis of the binary-lens microlensing event OGLE-2013-BLG-0911. The best-fit solutions indicate the binary mass ratio of q~0.03 which differs from that reported in Shvartzvald+2016. The event suffers from the well-known close/wide degeneracy, resulting in two groups of solutions for the projected separation normalized by the Einstein radius of s~0.15 or s~7. The finite source and the parallax observations allow us to measure the lens physical parameters. The lens system is an M-dwarf orbited by a massive Jupiter companion at very close (M_{host}=0.30^{+0.08}_{-0.06} M_{Sun}, M_{comp}=10.1^{+2.9}_{-2.2} M_{Jup}, a_{exp}=0.40^{+0.05}_{-0.04} au) or wide (M_{host}=0.28^{+0.10}_{-0.08} M_{Sun}, M_{comp}=9.9^{+3.8}_{-3.5}M_{Jup}, a_{exp}=18.0^{+3.2}_{-3.2} au) separation. Although the mass ratio is slightly above the planet-brown dwarf (BD) mass-ratio boundary of q=0.03 which is generally used, the median physical mass of the companion is slightly below the planet-BD mass boundary of 13M_{Jup}. It is likely that the formation mechanisms for BDs and planets are different and the objects near the boundaries could have been formed by either mechanism. It is important to probe the distribution of such companions with masses of ~13M_{Jup} in order to statistically constrain the formation theories for both BDs and massive planets. In particular, the microlensing method is able to probe the distribution around low-mass M-dwarfs and even BDs which is challenging for other exoplanet detection methods., Comment: 22 pages, 10 figures, Accepted for publication in The Astronomical Journal

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 soon after the planetary signal. The duration of the planetary signal is $\sim 2.5\,$hours. The measured ratio of the planet mass to its host star is $q = 4.2\pm 0.7 \times10^{-5}$. We further estimate that the lens system is likely to comprise a cold $\sim$3 Earth mass planet in a $\sim\,$2 AU wide orbit around a 0.2 Solar mass star at an overall distance of 7.1 kpc., 8 pages, 5 figures, accepted for publication in MNRAS

Introduction/Background Although peritoneal cytology in endometrial carcinoma was excluded from the staging system (FIGO 2008), the management for patients with positive peritoneal cytology remains controversial. The aim of this study is to evaluate the clinical significance of positive peritoneal cytology in G1/G2 endometrioid carcinoma. Methodology We retrospectively reviewed medical records of 365 patients with G1/G2 endometrioid carcinoma who were primarily treated at our hospital from 2005 to 2013. We analyzed clinicopathological features and prognosis of patients with positive (P group, N=45) and negative (N group, N=320) peritoneal cytology. Fisher9s exact test, Kaplan-Meier analysis, and Log-rank test were used for statistical analyses. Results Median age of all patients was 56 years-old (range 27–83), and stage distribution was 290/25/47/3 in stage I/II/III/IV (FIGO 2008). Median follow-up period was 61 months (range 1–130). The frequency of metastasis to adnexa, lymph nodes (LN), and distant organs was significantly high in P group compared with N group (p=0.0002, 0.0034, 0.0018, respectively). However, omental metastasis was not related with the results of cytology. The number of patients in low, intermediate, and high risk for recurrence defined in Japanese guidelines for treatment of uterine body neoplasm was 20/6/19 in P group and 202/62/56 in N group. Forty of 45 patients (89%) in P group received adjuvant treatment, while 110/320 (34%) in N group. Overall survival (OS) in P group was significantly poor compared with N group in patients with high risk for recurrence (75.0% vs 88.4% in 5-year OS, p=0.0067), although there was no difference in patients with both low and intermediate risks. Conclusion As the frequency of lymph node metastasis is significantly high, appropriate evaluation of lymph node metastasis is necessary in P group. Further, more effective adjuvant treatment is desirable for patients with high risk in P group to improve the prognosis. Disclosure Nothing to disclose.

Introduction/Background Treatment outcome of radiotherapy for uterine cervical adenocarcinoma (CA) is known to be poor compared with squamous cell carcinoma. Especially, the management for residual disease after radiotherapy remains unclear. The aim of this study is to evaluate the efficacy of salvage hysterectomy for residual disease after radiotherapy in patients with CA. Methodology Medical records of 28 patients with CA who underwent radiotherapy or concurrent chemoradiotherapy (CCRT) as primary treatment at our hospital between 2004 and 2015 were retrospectively reviewed. Clinicopathological features and prognosis of these patients were analyzed. Fisher’s exact test, Kaplan-Meier analysis, and Log-rank test were used for statistical analyses. Results Median age was 59 years-old (range 36–87), and stage distribution was 3/10/12/3 in stage I/II/III/IV (FIGO 2008). Histology was adenocarcinoma in 23 and adenosquamous carcinoma in 5. Six patients received radiotherapy alone (RT) and 22 patients received CCRT (one with CDDP and 21 with CDGP as chemotherapy). Eleven patients (39.3%) achieved complete remission (CR) after RT or CCRT (RT-CR group). Five patients with residual disease in uterus and without other extra-uterine lesions achieved CR by means of salvage simple or modified radical hysterectomy following RT or CCRT (OP-CR group). Consequently, 16 patients achieved CR in total. Overall survival (OS) in CR group was significantly favorable compared with non-CR group (74.5% vs 24.2% in 2-year OS, p=0.006). Especially, patients in OP-CR group had excellent prognosis with an 80% 5-year OS, which was comparable with a 61.4% 5-year OS in RT-CR group. There was no significant difference in clinicopathologial features between CR and non-CR groups. Thus, there was no predictive feature for radiation effect. Conclusion Salvage hysterectomy should be considered in patients with residual disease after radiotherapy, if they have no extra-uterine disease. Disclosure Nothing to disclose.

We report the discovery of a sub-Jupiter mass planet orbiting beyond the snow line of an M-dwarf most likely in the Galactic disk as part of the joint Spitzer and ground-based monitoring of microlensing planetary anomalies toward the Galactic bulge. The microlensing parameters are strongly constrained by the light curve modeling and in particular by the Spitzer-based measurement of the microlens parallax, $\pi_\mathrm{E}$. However, in contrast to many planetary microlensing events, there are no caustic crossings, so the angular Einstein radius, $\theta_\mathrm{E}$ has only an upper limit based on the light curve modeling alone. Additionally, the analysis leads us to identify 8 degenerate configurations: the four-fold microlensing parallax degeneracy being doubled by a degeneracy in the caustic structure present at the level of the ground-based solutions. To pinpoint the physical parameters, and at the same time to break the parallax degeneracy, we make use of a series of arguments: the $\chi^2$ hierarchy, the Rich argument, and a prior Galactic model. The preferred configuration is for a host at $D_L=3.73_{-0.67}^{+0.66}~\mathrm{kpc}$ with mass $M_\mathrm{L}=0.30_{-0.12}^{+0.15}~\mathrm{M_\odot}$, orbited by a Saturn-like planet with $M_\mathrm{planet}=0.43_{-0.17}^{+0.21}~\mathrm{M_\mathrm{Jup}}$ at projected separation $a_\perp = 1.70_{-0.39}^{+0.38}~\mathrm{au}$, about 2.1 times beyond the system snow line. Therefore, it adds to the growing population of sub-Jupiter planets orbiting near or beyond the snow line of M-dwarfs discovered by microlensing. Based on the rules of the real-time protocol for the selection of events to be followed up with Spitzer, this planet will not enter the sample for measuring the Galactic distribution of planets., Comment: Submitted to AAS Journals

Angelica keiskei Koidzumi (Ashitaba) is a large perennial herb that is native to the Pacific coast of Japan, and it has recently become popular as herbal medicine, dietary supplement and health food in Asian countries. The structures of various constituents isolated from Ashitaba such as chalcones, flavanones and coumarins have been precisely characterized, and many of them have bioactivities. A recent study clarified that Angelica keiskei exerts actions that lead to the prevention of thrombosis. Here, we introduce the possibility that ingesting Ashitaba could help to prevent thrombotic diseases.

A sample of 542 eclipsing binaries (EBs) with periods shorter than 2 d were selected from the Microlensing Observations in Astrophysics (MOA) EB catalogue (Li et al. 2017) for eclipse-time variation analysis. For this sample we were able to obtain the time series from MOA-II that span 9.5yr. We discovered 91 EBs, out of the 542 EBs, with detected light-travel-time effect signals suggesting the presence of tertiary companions of orbiting periods from 250 d-28 yr. The frequency of EBs with tertiary companions in our sample increases as the period decreases and reaches a value of 0.65 for contact binaries with periods shorter than 0.3 d. If only the contact binaries of periods < 0.26d are considered, the frequency even goes to the unit. Our results suggest that contact binaries with periods close to the 0.22-d contact binary limit are commonly accompanied by relatively close tertiary companions., 22 pages, 17 figures, MNRAS accepted

Angelica keiskei Koidzumi (Ashitaba) is a traditional folk medicine that is also regarded in Japan as a health food with potential antithrombotic properties. The ability of the major chalcones, xanthoangelol (XA) and 4-hydroxyderricin (4-HD) extracted from Ashitaba roots to inhibit platelet aggregation activity in vitro was recently determined. However, the anti-platelet activities of Ashitaba chalcones in vivo have remained unclear. The present study examines the anti-platelet effects of Ashitaba exudate and its constituent chalcones using mouse tail-bleeding models that reflect platelet aggregation in vivo. Ashitaba exudate and the major chalcone subtype XA, suppressed the lipopolysaccharide (LPS)-induced shortening of mouse tail bleeding. However, trace amounts of other Ashitaba chalcone subtypes including xanthoangelols B (XB), D (XD), E (XE) and F (XF) did not affect tail bleeding. These results suggest that the major chalcone subtype in Ashitaba, XA, has anti-platelet-activities in vivo.

We report the discovery of a possible planet in microlensing event MOA-2010-BLG-353. This event was only recognised as having a planetary signal after the microlensing event had finished, and following a systematic analysis of all archival data for binary lens microlensing events collected to date. Data for event MOA-2010-BLG-353 were only recorded by the high cadence observations of the OGLE and MOA survey groups. If we make the assumptions that the probability of the lens star hosting a planet of the measured mass ratio is independent of the lens star mass or distance, and that the source star is in the Galactic bulge, a probability density analysis indicates the planetary system comprises a 0.9^{+1.6}_{-0.53} M_{Saturn} mass planet orbiting a 0.18^{+0.32}_{-0.11} M_{sun} red dwarf star, 6.43^{+1.09}_{-1.15} kpc away. The projected separation of the planet from the host star is 1.72^{+0.56}_{-0.48} AU. Under the additional assumption that the source is on the far side of the Galactic bulge, the probability density analysis favours a lens system comprising a slightly lighter planet., 7 pages, 4 figures, MNRAS accepted

著者人数: 65名ほか (所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 鈴木, 大介), Accepted: 2018-03-27, 資料番号: SA1180046000

著者人数: 61名ほか (所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 鈴木, 大介), Accepted: 2018-05-02, 資料番号: SA1180047000

We present the first catalogue of eclipsing binaries in two MOA fields towards the Galactic bulge, in which over 8,000 candidates, mostly contact and semi-detached binaries of periods < 1 d, were identified. In this paper, the light curves of a small number of interesting candidates including eccentric binaries, binaries with noteworthy phase modulations and eclipsing RS CVn type stars are shown as examples. In addition, we identified three triple object candidates by detecting the light-travel-time effect in their eclipse time variation curves., 13 pages, 9 figures, MNRAS accepted

Up to this day, RICHes have been mainly used for high energy experiments to identify leptons and mesons. On the other hand, the number of Cherenkov photons is proportional to square of the atomic number, so that application of a RICH for heavy ions is expected. Then we are developing a ring-imaging Cherenkov counter for heavy ions (HI-RICH). The experiment was performed at NIRS-HIMAC. As for the primary beam ($^{132}$Xe with an energy of 420 MeV/u), a velocity resolution $\Delta\beta/\beta=0.050\%$ (standard deviation $\sigma$) and a detection efficiency $\varepsilon=99.9\%$ were achieved. Regarding to the secondary beam, a particle identification was successfully performed with HI-RICH and an ion chamber.

We detect a cold, terrestrial planet in a binary-star system using gravitational microlensing. The planet has low mass (2 Earth masses) and lies projected at $a_{\perp,ph}$ ~ 0.8 astronomical units (AU) from its host star, similar to the Earth-Sun distance. However, the planet temperature is much lower, T, Published in Science, Main and supplementary material combined

Background: Various factors contribute to the discrepancies observed between the bromocresol green (BCG) and bromocresol purple (BCP) assays of serum concentration. Either a BCG or a modified BCP assay is a routine laboratory for albumin measurement in Japan. High-dose of penicillin G underestimates serum albumin level using a modified BCP method in vitro. Therefore, we examined the serum albumin level in the patients treated with high-dose of penicillin G and also performed the experiments on coincubation with plasma, or albumin product and penicillin G solution in vitro. Methods: The medical records of 71 patients treated with high-dose of Penicillin G collected between 2009 and 2012 were reviewed for age, gender, biochemistry (total protein, albumin and potassium), underlying diseases and usage of albumin product. Patients were divided into 2 groups: BCG group (N = 38) and a modified BCP group (N = 33). We compared serum albumin levels between two groups. We performed the Original Research Article British Journal of Medicine & Medical Research, 4(6): 1293-1300, 2014 1294 experiments on co-incubation with albumin product or human plasma and penicillin G solution in vitro. Results: Serum albumin levels using a modified BCP assay decreased during the treatment with high dose penicillin G (-0.4 ± 0.1 g/dL), while serum albumin levels by a BCG method did not decrease (0.06 ± 0.05 g/dL). Although only one patient revealed hypoalbuminemia (

Seed dispersal by ants (myrmecochory) is a widely distributed plant–animal interaction in many ecosystems, and it has been regarded as a generalized (multiple species) interaction in which specialization on specific ant partners is uncommon. In this paper, we demonstrate species-specific seed dispersal of spotted spurge (Chamaesyce maculata) by ants in Japan. C. maculata produces seeds from summer to autumn in Japan. The seeds produced in autumn are carried by two ant species, Tetramorium tsushimae and Pheidole noda. We performed laboratory experiments to investigate the fate of C. maculata seeds in the nests of T. tsushimae and P. noda. P. noda consumed the seeds in the nest and rarely carried seeds out of the nest, while T. tsushimae consumed only the seed coat, and subsequently carried the seeds out of the nest. Removal of the seed coat by T. tsushimae may increase seed survival by reducing their susceptibility to infection by fungi. We also observed ant responses to filter paper soaked with an aqueous extract of the seed coat. P. noda did not react to the filter paper, but T. tsushimae carried the filter paper into their nest. Analysis by high-pressure liquid chromatography revealed that the aqueous extract contained at least four sugars and one unknown substance. Myrmecochory has been regarded as a generalized interaction with specialization for specific ant partners uncommon. However, our study suggests there is a species-specific interaction in seed dispersal by ants in autumn-flowering individuals of C. maculata in Japan.

Time delay in bilateral control system seriously deteriorates performance and stability. Acceleration-based bilateral control (ABC) is hybrid of position and force control in the acceleration dimension using the disturbance observer. It can be divided into two modal spaces: common and differential. The sum of master and slave forces is controlled to be zero in the common modal space (1,+1) to realize the law of action-reaction. The difference of master and slave positions is controlled to be zero in the differential modal space (1,-1) for position tracking. This brief analyzes the stability of each modal space under time delay. Based on modal space analysis, this brief proposes a novel four-channel (4ch) ABC architecture using two degrees of freedom proportional derivative (PD) control for haptic communication under time delay. In the proposed 4ch ABC, the difference of position is controlled to be zero by P-D control (differential proactive PD control), and the sum of the forces is controlled to be zero by damping-injected force P control. Furthermore, this brief utilizes frequency-domain damping design to realize both high performance and stability based on delay-dependent robust H∞ stability. The proposed 4ch ABC improves the stability of each modal space under time delay. The validity of the proposed control system is confirmed by some experimental results.

We report the discovery of a binary composed of two brown dwarfs, based on the analysis of the microlensing event OGLE-2016-BLG-1469. Thanks to detection of both finite-source and microlens-parallax effects, we are able to measure both the masses $M_1\sim 0.05\ M_\odot$, $M_2\sim 0.01\ M_\odot$, and distance $D_{\rm L} \sim 4.5$ kpc, as well as the projected separation $a_\perp \sim 0.33$ au. This is the third brown-dwarf binary detected using the microlensing method, demonstrating the usefulness of microlensing in detecting field brown-dwarf binaries with separations less than 1 au., Comment: 8 pages, 8 figures

著者人数: 55名 (JAXA職員: 鈴木, 大介), Accepted: 2017-08-08, 資料番号: SA1170115000

Simultaneous observations of microlensing events from multiple locations allow for the breaking of degeneracies between the physical properties of the lensing system, specifically by exploring different regions of the lens plane and by directly measuring the "microlens parallax". We report the discovery of a 30-55$M_J$ brown dwarf orbiting a K dwarf in microlensing event OGLE-2015-BLG-1319. The system is located at a distance of $\sim$5 kpc toward the Galactic bulge. The event was observed by several ground-based groups as well as by $Spitzer$ and $Swift$, allowing the measurement of the physical properties. However, the event is still subject to an 8-fold degeneracy, in particular the well-known close-wide degeneracy, and thus the projected separation between the two lens components is either $\sim$0.25 AU or $\sim$45 AU. This is the first microlensing event observed by $Swift$, with the UVOT camera. We study the region of microlensing parameter space to which $Swift$ is sensitive, finding that while for this event $Swift$ could not measure the microlens parallax with respect to ground-based observations, it can be important for other events. Specifically, for detecting nearby brown dwarfs and free-floating planets in high magnification events., 28 pages, 6 figures, 2 tables. Submitted to ApJ

The microlensing event OGLE-2008-BLG-510 is characterised by an evident asymmetric shape of the peak, promptly detected by the ARTEMiS system in real time. The skewness of the light curve appears to be compatible both with binary-lens and binary-source models, including the possibility that the lens system consists of an M dwarf orbited by a brown dwarf. The detection of this microlensing anomaly and our analysis demonstrates that: 1) automated real-time detection of weak microlensing anomalies with immediate feedback is feasible, efficient, and sensitive, 2) rather common weak features intrinsically come with ambiguities that are not easily resolved from photometric light curves, 3) a modelling approach that finds all features of parameter space rather than just the `favourite model' is required, and 4) the data quality is most crucial, where systematics can be confused with real features, in particular small higher-order effects such as orbital motion signatures. It moreover becomes apparent that events with weak signatures are a silver mine for statistical studies, although not easy to exploit. Clues about the apparent paucity of both brown-dwarf companions and binary-source microlensing events might hide here.

We propose the enhancement of Λ c yield in heavy ion collisions at RHIC and LHC as a novel signal for the existence of diquarks in the strongly coupled quark-gluon plasma produced in these collisions as well as in the Λ c . Assuming that stable bound diquarks can exist in the quark-gluon plasma, we argue that the yield of Λ c would be increased by two-body collisions between [ud] diquarks and c quarks, in addition to normal three-body collisions among u, d and c quarks. A quantitative study of this effect based on the coalescence model shows that including the contribution of diquarks to Λ c production indeed leads to a substantial enhancement of the Λ c /D ratio in heavy ion collisions.

We report the result of the analysis of the light curve of a caustic-crossing binary-lens microlensing event OGLE-2009-BLG-023/MOA-2009-BLG-028. Even though the event was observed solely by survey experiments, we could uniquely determine the mass of the lens and distance to it by simultaneously measuring the Einstein radius and lens parallax. From this, we find that the lens system is composed of M-type dwarfs with masses $(0.50\pm 0.07) \ M_\odot$ and $(0.15\pm 0.02)\ M_\odot$ located in the Galactic disk with a distance of $\sim 1.8$ kpc toward the Galactic bulge direction. The event demonstrates that physical lens parameters of binary-lens events can be routinely determined from future high-cadence lensing surveys and thus microlensing can provide a new way to study Galactic binaries.

Seeds are often carried by omnivorous ants even if they do not carry elaiosomes. Although many seeds carried by ants are consumed, both seeds abandoned during the seed carrying and leftover seeds are consequently dispersed (dyszoochory). These non-myrmecochorous seeds do not necessarily attract ants quickly. Therefore, these seeds often seem to be exposed to the danger of consumption by pre-dispersal seed predators. We propose the hypotheses, “seed predator deterrence hypothesis” that plants may benefit from seed-carrying ants if they deter seed predators from visiting plants, and seed-carrying ants may play additional roles in plant reproductive success, besides dyszoochory by ants. To test the hypotheses, we investigated the abundance of seed-carrying ants of the species Tetramorium tsushimae Linnaeus and Pheidole noda Smith F., and of the seed predatory stinkbug, Nysius plebeius Distat, on the spotted sandmat, Chamaesyce maculata L. Small, of which the seeds have no elaiosomes but are consumed by both ants and bugs. In the field, ants and stinkbugs seldom encountered each other on the plant. The number of stinkbugs beneath the plants with ants was smaller than that beneath the plants without ants. In laboratory experiments, the number of stinkbugs on the shoot was smaller when ants were present than when they were absent. These results might support the seed predator deterrence hypothesis: the probability of seed predation by stinkbugs seems to be reduced by the ant visits on plants and/or the existence of ants beneath the plants. This study highlights a new ant–plant interaction in seed dispersal by ants.

著者人数: 62名ほか（所属．宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 鈴木, 大介）, Accepted: 2018-07-23, 資料番号: SA1180096000

To elucidate roles of an omnivorous ant, Tetramorium tsushimae Emery, against pre-dispersal seed consumers in the seed dispersal of Chamaesyce maculata (L.) Small, the effects of the seed injury by a stinkbug, Nysius plebeius Distat, on the seed removal by the ant and the germination rate were examined in laboratory experiments. The ants of T. tsushimae removed more frequently non-injured seeds than injured seeds. Therefore, low removal frequency of injured seeds by T. tsushimae ants might facilitate the increase in removal frequency of non-injured seeds, consequently leading to efficient seed dispersal of C. maculata. The germination rate of injured seeds that N. plebeius nymphs sucked was conspicuously lower than the non-injured seeds. The germination rate of seeds that T. tsushimae ants carried out of their nest was similar to that of the non-injured seeds. Thus, seed removal by T. tsushimae ants has hardly effects on the germination of these seeds. Therefore, the preferential removal of non-injured seeds by T. tsushimae ants might contribute to the dispersal success of C. maculata seeds. These results might show a novel interaction between myrmecochorous plants and ants in which the assessment of seed quality by ants contributes to the reproductive success of plants.

We propose the enhancement of $\Lambda_c$ yield in heavy ion collisions at RHIC and LHC as a novel signal for the existence of diquarks in the strongly coupled quark-gluon plasma produced in these collisions as well as in the $\Lambda_c$. Assuming that stable bound diquarks can exist in the quark-gluon plasma, we argue that the yield of $\Lambda_c$ would be increased by two-body collisions between $ud$ diquarks and $c$ quarks, in addition to normal three-body collisions among $u$, $d$ and $c$ quarks. A quantitative study of this effect based on the coalescence model shows that including the contribution of diquarks to $\Lambda_c$ production indeed leads to a substantial enhancement of the $\Lambda_c/D$ ratio in heavy ion collisions., Comment: Prepared for Chiral Symmetry in Hadron and Nuclear Physics (Chiral07), Nov. 13-16, 2007, Osaka, Japan

A numerical model of time-dependent gas shielded metal arc is described, which was developed in order to make clear the kinetics of arc plasma together with metal transfer. It is possible to calculate and visualize time-dependent temperature and fluid flow field of argon shielded metal arc plasma with the grow-up and the subsequent detachment of the liquid metal drop at the wire tip. Numerical calculation shows that the arc shape in globular transfer abruptly changes at the moment of metal drop detachment. Whereas, the spray transfer arc seems to be stable and almost does not fluctuate with metal transfer.

The Microlensing Observations in Astrophysics (MOA) is a microlensing survey conducted at Mt. John Observatory in New Zealand. We searched transiting planet candidates from the MOA-I Galactic bulge data, which have been obtained with a 61cm B&C telescope from 2000 to 2005 for a microlensing search. Although this survey data were dedicated to microlensing, they are also quite useful for searching transiting objects because of the large number of stars monitored (~7 million) and the long span of the survey (~6 years). From our analysis, we found 58 transiting planet candidates. We are planning to follow up these candidates with high-precision spectroscopic and photometric observations for further selection, toward the detection of planets by radial velocity observations.

Experimental and numerical studies have been performed for the cure process of solid rubber. Styrene-butadiene rubber (SBR) packed in a cylindrical mold of inner diameter 74.6 mm, was heated by one-dimensional, transient heat conduction from the mold. Radial temperature profile and also radial distributions of the degree of cure were measured after the prescribed heating time was reached. Two methods for the mold temperature control were adopted. One is that the heating is continued at a constant temperature until the uniform temperature profile across the rubber was observed. The other is that the heating was cut off before the uniform profile was formed in order to study the effects of residual heat on the cure process. Numerical prediction was performed for the distributions of the temperature and degree of cure. Heat conduction equation for one-dimensional, transient heat transfer is coupled to the cure kinetics of the SBR. Heat generation term, expressed as a function of cure rate and the total heat generation due to cure reaction, is introduced to account for the effect of heat liberated during the process. Results of the prediction showed a good agreement of the measured profiles of the temperature and the degree of cure.

We report the discovery of a planet by the microlensing method, OGLE-2012-BLG-0724Lb. Although the duration of the planetary signal for this event was one of the shortest seen for a planetary event, the anomaly was well covered thanks to high cadence observations taken by the survey groups OGLE and MOA. By analyzing the light curve, this planetary system is found to have a mass ratio $q=(1.58\pm0.15)\times10^{-3}$. By conducting a Bayesian analysis, we estimate that the host star is an M-dwarf star with a mass of $M_{\rm L}=0.29_{-0.16}^{+0.33} \ M_{\odot}$ located at $D_{\rm L}=6.7_{-1.2}^{+1.1} \ {\rm kpc}$ away from the Earth and the companion's mass is $m_{\rm P}=0.47_{-0.26}^{+0.54} \ M_{\rm Jup}$. The projected planet-host separation is $a_{\perp}=1.6_{-0.3}^{+0.4} \ {\rm AU}$. Because the lens-source relative proper motion is relatively high, future high resolution images would detect the lens host star and determine the lens properties uniquely. This system is likely a Saturn-mass exoplanet around an M-dwarf and such systems are commonly detected by gravitational microlensing. This adds an another example of a possible pileup of sub-Jupiters $(0.2 < m_{\rm P}/M_{\rm Jup} < 1)$ in contrast to a lack of Jupiters ($\sim 1 - 2 \ M_{\rm Jup}$) around M-dwarfs, supporting the prediction by core accretion models that Jupiter-mass or more massive planets are unlikely to form around M-dwarfs., 22 pages, 7 figures, 2 tables, accepted for publication in ApJ

We report the discovery of a microlensing planet OGLE-2012-BLG-0950Lb with the planet/host mass ratio of $q \sim 2 \times 10^{-4}$. A long term distortion detected in both MOA and OGLE light curve can be explained by the microlens parallax due to the Earth's orbital motion around the Sun. Although the finite source effect is not detected, we obtain the lens flux by the high resolution Keck AO observation. Combining the microlens parallax and the lens flux reveal the nature of the lens: a planet with mass of $M_{\rm p} = 35^{+17}_{-9} M_{\oplus}$ is orbiting around a M-dwarf with mass of $M_{\rm host} = 0.56^{+0.12}_{-0.16} M_{\odot}$ with a planet-host projected separation of $r_{\perp} =2.7^{+0.6}_{-0.7}$ AU located at $D_{\rm L} = 3.0^{+0.8}_{-1.1}$ kpc from us. This is the first mass measurement from only microlens parallax and the lens flux without the finite source effect. In the coming space observation-era with $Spitzer$, $K2$, $Euclid$, and $WFIRST$, we expect many such events for which we will not be able to measure any finite source effect. This work demonstrates an ability of mass measurements in such events., Comment: 40 pages, 10 figures, 4 Tables. Accepted to AJ

Experimental study has been made during cure process of SBR/NR foam rubber. Rubber sample with 30 mm thick, made up by stacking thin rubber sheets in layers, was packed in a metal mold, and peroxide cure was performed by transient heat conduction. Rubber heating time was changed in several steps in order to study the effects of the cure time on the blowing characteristics. Also swelling test was conducted in order to study the relation between the cell structure and the crosslink density. Typical temperature field of one-dimensional, transient heat conduction was observed, and results of the observation studies showed that the cell structure changed depending on both the position from the heating surface and the heating time, and two extreme cell structure, open-cell foam, and closed-cell foam, was clearly observed. Image analyses of the cell structure showed that the porosity distribution increased with the increase of the distance from the heating surface, and the porosity was lower for longer heating time at a same position. Average area of the foam almost took similar results for the result of the porosity, and these various quantities were correlated to the crosslink density.

We developed a new bulk strained Si/SiGe CMOS technology free from any Ge-related problems, which has a 90- to 110-nm strained Si layer thicker than the limit at which misfit dislocations occur and a new shallow-trench isolation (STI) structure that has a selective-epitaxial-Si (SES) layer to cover up the SiGe trench surface. This technology has advantages in process compatibility with Si CMOS because it allows rough treatment of cap Si surface cleaning or sacrificial oxidation. The thick-strained Si exactly causes misfit dislocations at the interface of Si/SiGe, but no degradation of the internal strain was observed. The dislocation depth is deep enough to reduce the leakage current between source and drain. SES-STI has advantages in low junction leakage current and manufacturing compatibility with Si-CMOS process. The fabricated thick-strained-Si/SiGe 0.18-mum CMOS shows the same performance enhancement factor as the usual thin (< 20 nm) strained Si/SiGe. SES-STI reduced the junction leakage current by 1.5-2 decades from the conventional STI without epitaxial Si layer. Hot carrier lifetime is the same or rather longer than control Si, which means that the quality of the gate oxide on thick-strained Si is not inferior to that of control Si.