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A new target design is presented to model high-energy radiative accretion shocks in polars. In this paper, we present the experimental results obtained on the GEKKO XII laser facility for the POLAR project. The experimental results are compared with 2D FCI2 simulations to characterize the dynamics and the structure of plasma flow before and after the collision. The good agreement between simulations and experimental data confirms the formation of a reverse shock where cooling losses start modifying the post-shock region. With the multi-material structure of the target, a hydrodynamic collimation is exhibited and a radiative structure coupled with the reverse shock is highlighted in both experimental data and simulations. The flexibility of the laser energy produced on GEKKO XII allowed us to produce high-velocity flows and study new and interesting radiation hydrodynamic regimes between those obtained on the LULI2000 and Orion laser facilities.
Underwater endoscopic ear surgery does not require suction and so protects the inner ear from unexpected aeration that may damage its function in the treatment of labyrinthine fistula. A method of underwater endoscopic ear surgery is proposed for the treatment of superior canal dehiscence.
Underwater endoscopic ear surgery was performed for plugging of the superior semicircular canal through the transmastoid approach. Saline solution was infused into the mastoid cavity through an Endo-Scrub Lens Cleaning Sheath. The tip of the inserted endoscope was filled completely with saline water.
Using this underwater endoscopic view, the canal was clearly dissected to expose the semicircular canal membranous labyrinth and dehiscence area. No particular complication occurred during the surgical procedure.
The underwater endoscopic ear surgery technique for plugging in superior canal dehiscence secures an excellent visual field and protects the inner ear from unexpected aeration.
Much can be learned from terrestrial planets that appear to have had the potential to be habitable, but failed to realize that potential. Mars shows evidence of a once hospitable surface environment. The reasons for its current state, and in particular its thin atmosphere and dry surface, are of great interest for what they can tell us about habitable zone planet outcomes. A main goal of the MAVEN mission is to observe Mars’ atmosphere responses to solar and space weather influences, and in particular atmosphere escape related to space weather ‘storms’ caused by interplanetary coronal mass ejections (ICMEs). Numerical experiments with a data-validated MHD model suggest how the effects of an observed moderately strong ICME compare to what happens during a more extreme event. The results suggest the kinds of solar and space weather conditions that can have evolutionary importance at a planet like Mars.
We have made 12CO(J=1−0) observations of the LMC with NANTEN. We report the results of a comparison between CO clouds and SNRs in the LMC. Among the 35 known SNRs, only 10 are possibly associated with CO clouds. These 10 CO clouds and SNRs deserve follow-up studies for possible interactions. We present overlays of CO clouds on the optical images of some of these SNRs.
We have made 12CO(J=1-0) observations in the LMC with NANTEN, and compared the detected giant molecular clouds (GMCs) with HII regions and stellar clusters. It is found that ~ 80% of the GMCs are associated with HII regions. The results of comparisons of the GMCs with the HII regions and the stellar clusters are presented.
We have made a 12CO(J = 1−0) survey of the LMC with NANTEN. A sample of 55 giant molecular clouds has been identified and comparisons with stellar clusters, HII regions and SNRs are presented. The connection between the clouds and cluster formation is discussed.
We have made 12CO(J=1−0) observations of the LMC with the NANTEN millimeter-wave telescope and identified about 100 distinct giant molecular clouds (GMCs). A detailed comparison of the GMCs with stellar clusters and a UV image is discussed.
Fully sampled 12CO(J=1−0) observations of the whole extent of the LMC have been made with a linear resolution of ~ 30 pc at a detection limit of N(H2) = 2 × 1021 cm−2. In addition, several selected regions have been mapped with higher sensitivity corresponding to a detection limit of 1 × 1021 cm−2. Based on these results, a new estimate of the molecular mass in the LMC is presented.
In this paper the Very High Energy (VHE) gamma-ray astronomy program at the University of Adelaide is described. VHE gamma rays with energies above ~5 × 1011eV are observed using the atmospheric Cerenkov technique. Results from the first three years observations at Woomera and the current upgrading of the telecope are described. The CANGAROO project, a collaboration between the University of Adelaide and a number of Japanese institutions, is also introduced.
The CANGAROO project incorporates two Čerenkov imaging telescopes at Woomera to obtain stereo images of very high-energy gamma-ray (and cosmic-ray) showers. The first stereo observations, with one imaging system, were made in March 1992, and preliminary stereo imaging observations began in July 1992. This paper describes the stereo imaging technique, the sources under investigation, and the indications from the first data sets.
Time series of SXT (Soft X-ray Telescope) images have revealed many jet-like features in the solar corona. Typical size of the “jet” is 5 × 103 – 4 × 105 km, the typical projected velocity is 30 – 300 km/s, and the kinetic energy estimated to be 1025 – 1028 erg. Many of the jets are associated with flare-like bright points or sub-flares. Three typical examples are discussed, including an X-ray jet identified with an Hα surge. It is suggested that magnetic reconnection is one of the possible mechanisms to produce these X-ray jets.
The Collaboration of Australia and Nippon for a GAmma Ray Observatory in the Outback operates two large telescopes at Woomera (South Australia), which detect the Čerenkov light images produced in the atmosphere by electronpositron cascades initiated by very high energy (~1 TeV or 1012 eV) gamma rays. These gamma rays arise from a different mechanism than at EGRET energies: inverse Compton (IC) emission from relativistic electrons.
The spoke-like images are recorded by a multi-pixel camera which facilitates the rejection of the large numbers of oblique and ragged cosmic ray images. A field of view ~3.5° is required. The Australian team operates a triple 4 m diameter mirror telescope, BIGRAT, with a 37 photomultiplier tube camera and energy threshold 600 GeV. The Japanese operate a single, highly accurate 3.8 m diameter f/1 telescope and high resolution 256 photomultipler tube camera. In 1998 a new 7 m telescope is planned for Woomera with a design threshold ~;200GeV.
A fully coherent free electron laser (FEL) seeded with a higher-order harmonic (HH) pulse from high-order harmonic generation (HHG) is successfully operated for a sufficiently prolonged time in pilot user experiments by using a timing drift feedback. For HHG-seeded FELs, the seeding laser pulses have to be synchronized with electron bunches. Despite seeded FELs being non-chaotic light sources in principle, external laser-seeded FELs are often unstable in practice because of a timing jitter and a drift between the seeding laser pulses and the accelerated electron bunches. Accordingly, we constructed a relative arrival-timing monitor based on non-invasive electro-optic sampling (EOS). The EOS monitor made uninterrupted shot-to-shot monitoring possible even during the seeded FEL operation. The EOS system was then used for arrival-timing feedback with an adjustability of 100 fs for continual operation of the HHG-seeded FEL. Using the EOS-based beam drift controlling system, the HHG-seeded FEL was operated over half a day with an effective hit rate of 20%–30%. The output pulse energy was
at the 61.2 nm wavelength. Towards seeded FELs in the water window region, we investigated our upgrade plan to seed high-power FELs with HH photon energy of 30–100 eV and lase at shorter wavelengths of up to 2 nm through high-gain harmonic generation (HGHG) at the energy-upgraded SPring-8 Compact SASE Source (SCSS) accelerator. We studied a benefit as well as the feasibility of the next HHG-seeded FEL machine with single-stage HGHG with tunability of a lasing wavelength.
A series of Ce3+ doped Ca8La2(PO4)6O2 phosphors with tunable emission were successfully synthesized by traditional solid state reaction. The crystal structure and photoluminescence properties were studied through X-ray diffraction, photoluminescence excitation and emission spectra. The results indicated that Ca8La2(PO4)6O2:Ce3+ exhibited color-tunable emission due to the 5d-4f transitions of Ce3+ ions under different wavelength excitation. The optimal doping content of Ce3+ ions in Ca8La2(PO4)6O2 was found to be 5 mol%. The site-selective photoluminescence property and the reason for red-shift of the emission band along with Ce3+ content and the excitation wavelength were also studied in detail.
Blue and Green long-persistent luminescence materials have been fully developed, and are well featured in production and application. However, long-wavelength emitting materials are very rare relatively. This paper presents some work from our laboratory on the recent progress in long-wavelength emitting long-persistent luminescence materials: Sr3Al2O5Cl2: Eu2+, Tm3+, Sr2SnO4: Sm3+ and Ca2BO3Cl: Eu2+, Dy3+. The initial intensity of Sr3Al2O5Cl2: Eu2+, Tm3+ can reach nearly 5000 mcd/m2 and its afterglow can last about 220 min at recognizable intensity level. Sr2SnO4: Sm3+ has a red emission and its afterglow time of which sintered in vacuum atmosphere increased substantially. With optimum doping concentration and sufficient excitation with UV light, the yellow afterglow of Ca2BO3Cl: Eu2+, Dy3+ can persist over 48 h.
Excitation of multiple Er3+ ions upon absorption of a single high-energy photon increases Er-related emission at 1.5 μm, and therefore enhances UV/visible-to-IR photon conversion efficiency. Here we investigate this effect for layers of Er-doped SiO2 sensitized with silicon nanocrystals by measuring the quantum yield of 1.5 µm Er-related emission. We demonstrate dramatic increase of the emission commencing for excitation energies above a certain threshold value, as the number of Er3+ ions excited upon absorption of a single incoming photon increases. By comparing differently prepared materials, we show that the actual value of this threshold energy and the rate of the observed increase of the quantum yield depend on sample characteristics – the size of Si nanocrystals and the ratio of Er3+ ions and nanocrystals concentrations.
Spectral shifts of the emission lines of Erbium ions in Lithium Niobate are used to determine the build-up of intrinsic electric fields under intense light irradiation. The observed spectral shifts can be translated into internal electric fields through a calibration using applied external fields. The studies show that a substantial field can be created locally (up to 150kV/mm) with observed occasional electric breakthroughs that have a corresponding field strength of up to 35kV/mm. In addition, a modification of some Erbium incorporation sites is observed suggesting its relationship with a defect that can by photo-ionized, such as Fe2+/Fe3+.
Using a newly developed rapid test, an outbreak of human metapneumovirus (HMPV) infection in a long-term care facility was detected within only 2 days after the onset of symptoms in a putative index case. The outbreak was almost under control within 8 days mainly by zoning patients, with the exception of two cases of HMPV that were diagnosed 16 and 17 days after the onset of the outbreak. According to an immunological diagnosis as well as the rapid test, it was eventually proven that 18 patients had HMPV infections. We suspected that even asymptomatic residents, who had not been completely separated from the facility population, were a source of infection. That suggested that all asymptomatic residents should be tested and that the separation of the infected patients should be absolute, if an outbreak of HMPV infection is suspected in such a facility.
A solar eclipse is one of the most popular events in astronomy. Although it is the single astronomical event, it gives different images from place to place and changes in time. It is the most important message from astronomy to the public that an apparent face depends on the viewpoint and we should get the comprehensive view.