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We report here the results of deep optical spectroscopy of the very extended emission-line region (VEELR) found serendipitously around the Seyfert 2 galaxy NGC 4388 in the Virgo cluster. The Hα recession velocities of most of the filaments of the region observed are highly blue-shifted with respect to the systemic velocity of the galaxy. The velocity field is complicated, and there seem to be several streams of filaments ranging from ~ −100 km s−1 to ~ −700 km s−1 with respect to the systemic velocity of the galaxy. The emission-line ratios of the VEELR filaments are well explained by power-law photoionization models with solar abundances. In addition to photoionization, shock heating probably contributes to the ionization of the gas. We conclude that the VEELR was formerly the disk gas of NGC 4388, which has been stripped by ram pressure due to the interaction between the hot intra-cluster medium (ICM) and the galaxy.
We report on the status of the CCD cameras for the Kiso 105-cm Schmidt telescope. We have two types of cameras – single-chip and mosaic. The single-chip camera is available for common use. At present about 90 % of the telescope time is allocated to observations with CCD cameras.
Experimental Echinococcus multilocularis infection and deworming was repeated three or five times in nine dogs at various re-infection schedules. The mean number of worms decreased more than 91% in dogs with repeated infection, compared to first infection controls (n= 6). The copro-antigen assay and the egg count in the faeces suggested that the worm burden gradually decreased each time the dogs were re-infected. To examine whether such worm exclusion was a non-specific response, five dogs were sequentially infected with the parasite four times and subsequently fed freely for 6 months. Even after the 6-month interval, the five dogs that were infected five times with the parasite were still able largely to exclude the adult worms. The results suggested that the ability of worm exclusion in dogs that developed a resistance did not become rapidly extinct. Observation of the condition of faeces and the excretion of hooks in the faeces of repeatedly infected dogs revealed that the exclusion of worms started at the first week after the re-infection, and it continued during the patent period. Serum antibodies specific to the parasite antigen increased gradually until the third infection and significantly decreased during the 6-month interval. There was little enhancement of serum antibodies after the fifth infection in most dogs, although no clear correlation was observed between the antibody response and the worm burden. These findings suggested the possibility of developing a vaccine.
We have investigated electronic band-gap states in AlGaN/GaN hetero-structures with different growth conditions of GaN buffer layers from a viewpoint of Carbon impurity incorporation into GaN, using photoluminescence (PL), capacitance-voltage (C-V) and steady-state photo-capacitance spectroscopy (SSPC) techniques. The Carbon incorporation was found to be enhanced with decreasing the growth temperature of the GaN buffer layer between 1120 and 1170 °C. Acting in concert, three specific deep levels located at ~2.07, ~2.70, and ~3.23 eV below the conduction band were found to become dense significantly at the low growth temperature. Therefore, these levels are probably attributable to Ga vacancies and/or Carbon acceptors produced by the Carbon impurity incorporation, and are likely in conjunction with each other.
High resolution plan view images of clean and Au deposited Si(111) surfaces are presented. Corner holes and small holes between dimers of the DAS model of the 7×7 structure were clearly resolved. In the case of the Si(111)5×1-Au structure the 5 times period fringes did not show fine details.
The mesostructured vanadia/surfactant composites are synthesized by self assembled processes and phase transition has been investigated. The lamellar mesostructure of the vanadia/surfactant has been shifted to monoclinic and hexagonal mesophase by low temperature annealing, possibly due to the change of the inorganic/surfactant ratio.
A carbon nanotube triode using Helicon Plasma-enhanced CVD with electroplated NiCo catalyst has been successfully fabricated. Isolated NiCo based metal catalyst was deposited at the bottom of the cathode wells by electroplating methods to control the density of carbon nanotubes and also reduce the activation energy of its growth. Helicon Plasma-enhanced CVD (HPECVD) has been used to deposit nanotubes at 400°C. Vertically aligned carbon nanotubes were then grown selectively on the electroplated Ni catalyst. Field emission measurements were performed with a triode structure. At a cathode to anode gap of 1.1mm, the turn on voltage for the gate was 170V.
Domain wall velocity and nucleation rate in 250nm-thick epitaxial Pb(Zr,Ti)O3 thin films were studied by piezoresponse scanning force microscopy (PFM). Domain growth observed after applying switching pulses shorter than the switching time can be described using the Ishibashi theory. At a pulse voltage of +5V, experimental results indicated that new nucleation occurred during the switching period, which corresponded to the Category I in the Ishibashi theory. Switching time, domain wall velocity and nucleation rate at +5V can be obtained as 70ns, 8.3m/s and 43μs-1 μm-2, respectively. As compared with experimental results reported in BaTiO3 single crystals, domain wall velocity was much smaller but nucleation rate was much larger than those in single crystals.
We present a summary of recent progress towards the understanding of the valence-band physics in wurtzite GaN. Systematic studies have been performed on the strain dependence of the free exciton resonance energies by photoreflectance measurements using well-characterized samples. Analyzing the experimental data with the Hamiltonian appropriate for the valence bands, the values have been determined of the crystal field splitting, the spin-orbit splitting, the shear deformation potential constants, and the energy gap in the unstrained crystal. Discussions are given on the strain dependence of the energy gaps, of the effective masses, and of the binding energies for the free exciton ground states as well as on the valence band parameters. Using the obtained values and the generalized Elliott formula, the fundamental optical absorption spectra obtained experimentally were analyzed. The values of the elastic stiffness constants, which play a crucial role to determine the shear deformation potential constants, are also given.
Bi2Te3-based thin films were fabricated on glass substrates by the pulsed laser deposition (PLD) method. The vapor pressures of Bi and Te are significantly different, so controlling the stoichiometric composition is difficult when using conventional physical vapor deposition techniques, and the thermoelectric properties of Bi2Te3 films are sensitive to the film composition. PLD is a promising technique for the fabrication of telluride-based films such as Bi2Te3 due to its superior capability for controlling the film composition. Another advantage of PLD is the flexibility that it allows in terms of atmosphere in the reaction chamber; high concentrations of gases such as oxygen or argon can be introduced. We have measured various compositions of Bi2Te3 based films, and have identified the optimal compositions for both n-type and p-type material. The thermal conductivities of these Bi2Te3 films were evaluated by an exact measuring system, and the results were twice as low as those of conventional bulk materials. These results suggest that PLD has significant advantages for the deposition of in-plane Bi2Te3-based thin films.
A main topic at this meeting is how galaxies are affected when they enter for the first time the cluster environment from the outskirts. Most of the times we are forced to infer the environmental effects indirectly, relying on systematic variations of galaxy properties with environment, but there aren't many examples of direct observations able to unveil ongoing transformations, and the corresponding mechanism producing it. We present a case in which it is possible to identify the cluster environment, and in particular the intracluster medium and the recent infall history of galaxies onto the cluster, as the cause for a recent, abrupt change in the evolutionary history of galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html
The survey of Vibrio cholerae O1 in marine area was carried out in the Port of Osaka, Japan in 1987–2001, and 51 V. cholerae O1 strains were isolated. All strains were identified to be of El Tor biotype, Ogawa serotype and classic Ubon Kappa-phage type, and were cholera toxin (CT)-negative and CT gene-negative. In order to clarify certain ecological aspects of V. cholerae O1 in the marine environment of the temperate zone, we performed molecular analysis of the isolated strains using pulsed-field gel electrophoresis (PFGE) with NotI and SfiI restriction enzymes. We found the indistinguishable strains by DNA analysis using PFGE with strains passed for 1 year, and also found the closely related strains with that passed for 3 and 12 years. Those results indicated that V. cholerae O1 can survive over one winter at least, and that it survives in marine water for a long time by undergoing continuous mutation.
Negative ion states for Li atoms are found in graphite nanoclusters heavily doped with lithium using a semiempirical calculational method. These calculations identify a quasi-stable site for a negative Li ion near the terminated hydrogen atoms, and this site becomes very stable in the presence of the Coulomb interaction between Li ions. The total charge transfer from Li ions to the graphite clusters does not depend on the number of Li atoms per cluster but rather on the relative geometries of the Li atoms on the cluster. The relationship of these findings to the findings in the 7Li nuclear magnetic resonance experiments and to the performance of Li secondary batteries is discussed.
Synthetic andradite (Ca3Fe2Si3O12) has been compressed to loading pressures >21 GPa and heated to ∼1000°C by a YAG laser in a Diamond Anvil Cell (DAC). After quenching to room temperature, X-ray diffraction of the sample, still held at 21 GPa, showed that andradite had transformed to a cubic perovskite type polymorph with a = 3.460(4) Å. Upon decompression the perovskite phase transformed into an amorphous phase. The density of the perovskite polymorph (Ca3Fe2Si3O12) is ∼13.6% greater than that of isochemical andradite at 21 GPa. Ferric iron replaces Ca2+ and Si4+ in the perovskite structure (Fe3+ + Fe3+ = Si4+ + Ca2+), giving a formula unit: (Ca,Fe3+)(Si,Fe3+)O3. The new Fe3+-rich Ca-perovskite may provide new insight into the controls on the electrical conductivity of the lower mantle.
A microwave plasma generator, which functions under high pressure, has been developed and used in the fabrication of fine carbon particles. The plasma generator is a two-stage-type resonator, which consists of rectangular and semi-cylindrical-type resonators which are coupled in series for torching plasma and keeping it stable under high pressure. The plasma can be torched in helium gas at 3 × 106 Pa by tuning the dimensions of apparatus elements. Fine carbon particles of ~50 nm are obtained using a mixture of helium and methane gas. The particles are found to be crystalline from the results of transparent electron microscopy and diffraction analysis.
As the degree of large-scale integration (LSI) increases, the area of a single transistor will diminish and the density of transistors will increase. Accordingly, technology for high-density wiring to interconnect the huge number of transistors is needed because transistors cannot perform any useful functions without interconnects and electrodes. For advanced microprocessor chips with a sub-half-micron design rule and at least four interconnect layers, the minimum width of the interconnects becomes less than 0.35 μm.
Aluminum or an aluminum alloy is now generally used as the interconnect material in LSI circuits because the physical and chemical properties of aluminum are compatible with current LSI processing: Aluminum forms a thin protective oxide film that withstands various thermal processes; it has relatively low electrical resistivity and halide compounds with a relatively high vapor pressure which are suitable for reactive ion etching (RIE), and it is an inexpensive material. The reliability of aluminum interconnects, however, is a major concern for maintaining the total reliability of advanced LSI. Because of its relatively low melting point, aluminum as an interconnect material is susceptible to stress- and electromigration, which leads to open failure of the interconnect. It is well-known that these failure modes are accelerated by decreasing the width and thickness of the interconnects. Hence, use of aluminum interconnects may be limited for future sub-half-micron LSIs.
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