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CRL2688 is suggested to be one of the proto-planetary nebulae which are probably at a stage in which the central star is evolving from the red giant phase with rapid mass loss (Zuckerman 1978). The bipolar shape in both the optical and H2 emission indicates that a dense toroid of dust and gas obscures the star and surrounds the optical emission. The toroid is probably responsible for channelling the mass loss to the polar directions (Ney et al. 1975, Morris 1981, Beckwith et al. 1984). We present the results of mapping observations of CO (J = 1-0) emission from the expanding molecular envelope (Zuckerman et al. 1976, Lo et al. 1976, Knapp et al. 1982, Thronson et al. 1983) of the bipolar reflection nebula CRL2688 using the Nobeyama 45-m telescope with a 1.5″ resolution at a 7″.5 observing spacing.
We have made high resolution (2-5″) CO observations of seven IR luminous (LIR > 1011 LO) galaxies. They are Arp220, Mrk231, NGC6240, NGC6090, NGC695, Mrk331 and NGC828. We can resolve CO emission from all the galaxies but Mrk231 (figure 1).
We present our recent results of high spatial resolution(2″-6″) CO and 13CO(J=1−0) observations with the Nobeyama Millimeter Array(NMA). We observed the central (1-2 kpc) regions of nearby galaxies, IC342, Maffei2, and NGC6946 with 2″-4″ resolution (45-90 pc) in CO and 13CO, and the 3' region of M51 with 4″-6″ resolution (180-280 pc). We discuss the structures and kinematics of molecular gas in the central region of nearby late-type spiral galaxies, and in spiral arms, and discuss the trigger of star formation from viewpoints of galactic shock, gas fueling by bars.
NUMO and JAEA have been conducting a joint research since FY2011, which is aimed
to enhance the methodology of repository design and performance assessment in
preliminary investigation stage for the deep geological disposal of high-level
radioactive waste. As a part of this joint research, we have been developing
glass dissolution models which include various processes derived from
glass-overpack-bentonite buffer interaction, considering the precipitation of
Fe-silicates associated with steel overpack corrosion, and Si transport through
altered layer of glass. The objective of this modeling work is to show
comprehensively the lifetime of the vitrified waste due to glass matrix
dissolution timescales through sensitivity analysis, and to identify the
feature/process that most strongly influences the lifetime, and to identify
future R&D issues that would help to improve the nuclide transport
analysis with confidential value and the safety case in future. The sensitivity
analysis suggested that the duration of the glass dissolution might be predicted
in the ranges from 3.8×103 to 1.9×105
years. Also, the results indicated that the precipitation of
Fe–silicate has the strongest influence on the long-team behavior of
The distribution of H2O masers in the Sgr B2 core was observed with a 2.5′×2.5′ wide field and with 540 km s−1 total velocity coverage by the Nobeyama Millimeter Array. Thirty-nine resolved maser spots were detected with a relative positional accuracy of 0.3″, which are clustered into four separate regions. In Sgr B2 north, the cluster lies at the edge of the continuum ridge. One of the maser spots shows strong and wide velocity-spread emission, suggesting it may correspond to a center of star forming activity. In Sgr B2 main, the strong maser spots are projected just on the face of a compact HII region, and are red-shifted relative to the central velocity of the HII region. There are two possibilities to interpret our results in Sgr B2 (M). One is that the H2O maser spots are distributed around the HII region and are infailing to the HII region. The other is that the H2O maser sources are associated with the cloud in the foreground of the HII region.
We report NH3 observations of the Sgr A complex region including Sgr A West and the 20 km/s and 50 km/s molecular clouds (M–0.13–0.08 and M–0.02–0.07) using the Nobeyama Millimeter Array and the 45m telescope. NH3(1,1) and (2,2) lines were simultaneously observed to estimate the kinetic temperature. Our results suggest strong interaction between the molecular clouds and the continuum sources in the Sgr A complex. The interaction with continuum sources might be an important factor in determining the physical conditions of molecular gas in the galactic center region.
In Japan, there is a plan for Large Millimeter Array proposed by Nobeyama Radio Observatory. The proposed array may consist of 50 10-m antennas distributed in a 2 − 3 km area at very high altitude. In this paper, scientific directions, planned system, and site survey for the LMA are reported.
We have made aperture synthesis observations of CS(J=l-0, 2-1) and NH3(1,1) lines and 49, 98, and 110 GHz continuum in NGC2071-1RS with the Nobeyama Millimeter Array. Wfe have obtained maps of these lines and continuum maps with 2”. 7-20” resolution, ffe have found that dense molecular gas has a disk structure with a radial scale ranging 0.01 pc - 0.1 pc and has a ring-like structure with expanding motion at the central 5000 AU region. We also have found that there exists double dust continuum sources which are separated by 2500 AU in projection and are apparently located at the inner edges of the ring. Our observational results suggest that the disk of molecular gas has a central hole formed by wind and UV radiation from a central young stellar object, the central part is expanding, and that dust continuum emission comes from tangential parts of the shock compressed ring (r~1300 AU, M(H2)~ 21-34 Mo, and n(H2)~ 109) at the most inner side of the disk structure. The other possible model of the dust continuum sources is a binary system of self-luminous young stellar objects.
We made aperture synthesis CO(l-O) observations of the central region of Arp220 with the Nobeyama Millimeter Array. Central CO emission was resolved with a size of 975 kpc. It shows a ring-like structure (ɪ ~ 500 pc) with a large velocity gradient, 393 km · s−1 · kpc−1, from southwest to northeast direction. The ring-like emission is located around double radio compact sources. No emission peak was found in the center of the double sources within the velocity range 5100 km s−1to 5800 km s−1. These results suggest that an inclined massive gas ring has been or is being formed in the central 1 kpc of Arp220. Most of the molecular gas in Arp220 is concentrated on this nuclear ring. The radio compact sources are probably located at the inner egde of the ring.
This paper describes an approach for assessing the geosphere performance of nuclear waste disposal in fractured rock. In this approach, a three-dimensional heterogeneous channelnetwork model is constructed using a stochastic discrete fracture network (DFN) code. Radionuclide migration in the channel-network model is solved using the Laplace transform Galerkin finite element method, taking into account advection-dispersion in a fracture network, matrix diffusion, sorption in the rock matrix as well as radioactive chain decay. Preliminary radionuclide migration analysis was performed for fifty realizations of a synthetic block-scale DFN model. The total radionuclide release from all packages in the repository was estimated from the statistics of the results of fifty realizations under the hypothesis of ergodicity. The interpretation of the result of the three-dimensional network model by a combination of simpler one-dimensional parallel plate models is also discussed.
The stability of several kinds of substrates, such as Corning #1737 glass, fused silica, synthetic silica, water free synthetic silica, zinc selenide, silicon, and diamond like carbon (DLC) coated Si in supercritical water (663K and 25MPa) were examined. Their reaction with the water was evaluated by using Fourier transform infrared (FT-IR) spectroscopy. As a result of the present experiment, it was found that DLC-coated Si is one of the most stable and useful substrates for IR spectroscopy in supercritical water.
InSb1-xNx was grown on GaAs substrate by low-pressure metalorganic vapor phase epitaxy. Carrier gases were hydrogen or the mix of hydrogen and nitrogen. In both cases, X-ray analysis demonstrated that nitrogen was incorporated into InSb1-xNx up to 0.24.
A total of 321 Salmonella typhimurium strains of bovine origin obtained in northern Japan during the period 1970–1979 were tested for drug resistance and detection of conjugative R plasmids. Three hundred and eighteen (99·1 %) of these strains were resistant to one or more drugs. The isolation frequency of multiply drug-resistant strains tended to increase year by year. Two hundred and thirty-seven (74·5%) of these resistant strains carried conjugative R plasmids. A total of 308 R plasmids including 174 (56·5 %) thermosensitive (ts) R plasmids were derived from the 237 drug-resistant strains, indicating that 71 (30·0%) strains have two different conjugative R plasmids in a single host cell. Of the 308 R plasmids examined for fertility inhibition (fi), 167 ts and 131 non-ts R plasmids were fi−. Of the 60 ts R plasmids examined for incompatibility, 50 were classified into H1 group and 10 into H2 group. Of the 52 non-ts R plasmids examined, 35 were classified into the Iα group and the remaining plasmids were untypable in our tests. Mercury resistance marker was found in about 20% of H1 R plasmids coding for multiresistance, and all of H2 R plasmids coded for resistance to tellurite. The clonal distribution of an S. typhimurium strain which carried an H1 R plasmid coding for resistance to six drugs and mercury was recognized in 1978 and 1979.
A novel stimulated trapped electron-acoustic wave scattering instability by a linearly polarized laser interacting with a subcritical density plasma layer is observed by particle simulation. Its spectrum in the early stage is well-explained by a resonant three-wave parametric decay process and it takes place whether the ion dynamics are taken into account or not. When ion dynamics are considered, the excitation of the ion electrostatic wave, the generation of the electromagnetic (EM) soliton and the formation of ion vortices due to the large EM soliton, etc., are studied.
The generation of low-frequency radiation at around the terahertz frequency, caused by a linearly polarized intense laser pulse passing through a low-density homogeneous plasma, is studied by one-dimensional particle simulations. The excited transverse current component with its frequency at the electron plasma frequency serves as a radiation source to generate electromagnetic waves both in the front and the rear side vacuum regions of the plasma layer. It is found that the electromagnetic radiation fields increase with both increasing plasma density and increasing laser amplitude.
Three-dimensional electrostatic particle simulations are performed in order to investigate the effects of ion flow parallel to magnetic-field lines and their velocity shears on low-frequency plasma instabilities in detail. In the case where the ion drift speed is so small that the low-frequency instabilities cannot take place, the ion-acoustic wave is destabilized by introducing the ion-flow velocity shear. The ion-acoustic wave is locally destabilized in the large velocity shear region. On the other hand, the ion-cyclotron instability is also destabilized when the ion drift speed exceeds a certain threshold. The flow velocity shear enhances not only the fundamental mode but also the high harmonic modes. As a result, the spiky fluctuations in the time domain are locally observed in the velocity shear region, which are caused by the simultaneous existence of several coherent ion-cyclotron harmonics.
A new and simple approach for stellarator edge modeling is presented. This is based on averaging of edge plasma parameters and introducing effective two-dimensional flux surfaces which allow us to use the UEDGE transport code, widely used for tokamak edge plasma modeling. This approach is applied to edge modeling of the Large Helical Device (LHD). It should be noted that our model is based on a two-dimensional configuration which is called the stellarator-equivalent tokamak (SET), while a stellarator system is inherently three-dimensional. Numerical simulations show that a bump of ion density in the private flux region just inside the separatrix appears, and flow reversal or a vortex structure of the ion flow is observed. Detailed analyses are necessary for validating this approach.
The mechanism of electron acceleration by intense laser pulse
interacting with an underdense plasma layer is examined by
one-dimensional particle-in-cell (1D-PIC) simulations. The standard
dephasing limit and the electron acceleration process are discussed
briefly. A new phenomenon, of short high-quality, well-collimated
return relativistic electron beam with thermal energy spread, is
observed in the direction opposite to laser propagation. The process of
the electron beam formation, its characteristics, and the time-history
in x and px space for test
electrons in the beam, are analyzed and exposed clearly. Finally, an
estimate for the maximum electron energy appears in a good agreement
with simulation results.
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