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We have performed Smoothed Particle Hydrodynamics (SPH) simulations in order to understand the dynamical structures of Galactic Center molecular clouds. In our study it was found that the structures of GC molecular clouds could be induced by the combined effects of a gravitational perturbation by rotating bar potential and the hydrodynamic collisions between the clouds.
It is not certain that the ten annotated plays of Euripides came to be grouped by a process of selection based on some definite critical principle. In any case, it is something of a paradox that the Andromache, which has a long history of negative criticism, finds itself alongside plays, the reception of which has been much more favourable. The remark found in the second, probably Aristophanean, hypothesis: τό δέ δρμα τν δευτέρων has met with the agreement of several scholars who have found the play unsatisfactory. Verrall believed that on a straightforward reading the drama was worthless and unintelligible; Wilamowitz came to the conclusion that the play is ‘euripideisch in Gutem und Bösem und verdient die Zensur τν δευτέρων, die Aufnahme in eine Auswahl schwerlich’. According to Schmid-Stählin Euripides himself was not unaware of the drama’s shortcomings, for, as can be deduced from the scholium on 1. 445, he was too ashamed to produce it in Athens, and he did not, it seems, produce it in his own name.
However much we may disagree about the meaning and function of the Iris-Lyssa scene in Euripides’ Heracles (815-73), we can be certain of one thing: it was meant to be startling. We can find, it is true, a handful of examples of the appearance of a deity in mid-action in tragedy, and no single feature of the scene to be discussed is without parallel, but viewed as a whole it is unique among the extant plays and the plays for which we have fragmentary evidence. For example, the appearance of Athena in Rhesus 595 ff. and the probable appearance of Artemis and Apollo during the course of Sophocles’ Niobe (cf. frs. 441a, 442, 445 Radt), must have been striking, but in each case the supernatural visitation advances the plot along not unexpected lines. In our scene the intervention of Iris and Lyssa drives the second part of the play in a completely surprising direction. Again, it is remarkable that two speaking characters appear and then not to agree but to quarrel heatedly about Lyssa’s assignment. The only even remote parallel is the discussion between Kratos and Hephaistos in Prometheus where the deities speak and act on ground-level and are found not at a crucial turning-point in the middle of the play, but at its beginning, when the disagreement of the speakers is a curtain-raiser to the more significant discord which pervades the drama.
Most classical journals report on research on literary, historical and linguistic questions, and rarely allocate space to discussions of pedagogy at tertiary level. This article, however, falls into the latter category. It takes the form of a report on the teaching of Latin and Greek (both classical and post-classical) in universities in Australia and New Zealand; and it makes a number of suggestions regarding the future of the classical languages in this region.
Any general examination by an outsider of the situation of Classics in Australian and New Zealand universities would readily conclude that most departments are managing well, or at least holding their own, compared to other disciplines. Student enrolments are high overall, since most departments, like those in Britain and North America, have expanded their teaching range to embrace ancient history, classical literature in translation and, in some cases, archaeology. This has been the situation for the best part of the last two decades. Often these subjects were introduced in order to ‘subsidise’ and protect the continuance of Greek and Latin with their smaller numbers; but they have been extremely popular with students in every university in Australasia in which they are taught. And so these teaching areas have come to have a life and a rightful presence of their own.
We report on metal-oxide-semiconductor (MOS) AlGaN/GaN heterostructure field effect transistors (HFETs) based on InGaN/GaN multiple quantum well (MQW) structure using Ta2O5 dielectric deposited by electron beam evaporation (EBE) simultaneously for surface passivation and as a gate insulator. The device features a 5-pair MQW layer inserted into the AlGaN/GaN two-channel HFET structure. It results in a raised potential barrier, which leads to better carrier confinement and effective access to the InGaN layer. However, it revealed a pronounced leakage current which may be generated from the bottom Si-doped GaN and/or the sidewall leakage paths due to the exposure of channels after mesa etching. Both passivated MQW-HFET and MOS MQW-HFET present enhanced dc- and pulsed-mode performance compared to unpassivated one. In terms of transfer characteristics, MOS MQW-HFET exhibits the larger and broader main peak yet smaller satellite peak relative to passivated MQW-HFET. The reduced gate and mesa-to-mesa leakage current indicates the successful passivation effect from EBE-Ta2O5 dielectric.
SiB6 has proved to a potentially useful material because of its excellent thermoelectrical properties above 700°C, low specific gravity, high degree of hardness, and moderate melting point. SiB6, which has poor sinterability with a conventional sintering technique due to the covalent characteristic, has been successfully densified fully using a spark plasma sintering(SPS) method. The SPS-processed specimens consisted of SiB6, SiB4 and SixBy phases. Pure SiB6 powder were densified fully at the sintering temperature of 1600°C. In particular, it was found that the rare earth element was very effective in evolving the microstructure of SiB6 phase, resulting in reducing the sintering temperature and controlling grain growth. These effects were discussed in details in terms of microstructure evolution during the SPS process.
The feasibility of in situ phosphate- and metal- (calcium, aluminum, and iron) solution treatment for 90Sr immobilization was investigated. Batch and column experiments were performed to find optimum conditions for coprecipitation of 90Sr with Ca-, Al-, and Fe-phosphate compounds in contaminated soils. Separate columns were packed with artificially 85Sr-contaminated acid soil as well as 90Sr-contaminated soil from the Oak Ridge Reservation. After metal-phosphate treatment, the columns were then leached successively with either tapwater or 0.001 M CaCl2 solution. Most of the 85Sr coprecipitated with the metal phosphate compounds. Immobilization of 85Sr and 90Sr was affected by such factors as solution pH, metal and phosphate concentration, metal-to-phosphate ratio, and soil characteristics. Equilibration time after treatments also affected 85Sr immobilization. Many technology aspects still need to be investigated before field applications are feasible, but these experiments indicate that phosphate-based in situ immobilization should prevent groundwater contamination and will be useful as a treatment technology for 90Sr-contaminated sites.
ZnO with hexagonal wurzite structure is a wide band gap n-type semiconductor. ZnO films can be prepared to obtain high transparency in the visible range, low resistivity, chemical stability and stability in hydrogen plasma including many foreign materials such as Al, In. In this work, we prepared ZnO:Al thin film by Facing Targets Sputtering system with Zn metal target and ZnO:Al(Al2O3 2wt%, 4wt%) ceramic target at total working gas pressure 1mTorr, substrate temperature R.T.. We evaluated the crystallographic, electrical and optical characteristics of the ZnO:Al films.
WO3 doped TiO2 nanotube(WO3-doped TNT) thin film was fabricated by anodizing the TiO2 nanotube (TNT) film in an NH4F electrolyte containing WO4- ions. The sample was characterized by Field Emission Scanning Electron Microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–Vis diffuse reflectance spectroscopy (DRS). The results show that WO3 was successfully doped into TiO2 nanotubes and the absorption edge of WO3 doped TNT appeared to be red shifted. The photoelectrocatalytic (PEC) activity of WO3 doped TNT electrode was evaluated through the PEC degradation of aqueous Acid Blue 80. The experimental results demonstrated that the PEC degradation rate of WO3 doped TNT is increased by 48% and by 167% over that of non-doped TNT under UVA light irradiation and visible-light irradiation, respectively, at an applied potential of 1.54V. The degradation rates of WO3 doped TNT under photocatalytic (PC), electrochemical (EC), and PEC processes were compared. The results reveal the synergetic effect of PC and EC processes.
The characteristics of high energy protons generated from thin carbon-proton mixture targets via circularly polarized intense laser pulses are investigated using two-dimensional particle-in-cell simulations. It is found that the density ratio n between protons and carbon ions plays a key role in determining the acceleration dynamics. For low n values, the protons are mainly accelerated by the radiation pressure acceleration mechanism, resulting in a quasi-monoenergetic energy spectrum. The radiation pressure acceleration mechanism is enhanced by the directed-Coulomb-explosion of carbon ions which gives a high proton maximum energy, though a large energy spread, for high n values. From a proton acceleration point of view, the role of heavy ions is very important. The fact that the proton energy spectrum is controllable based on the target composition is especially useful in real experimental environments.
The (Ga1−xMnx)N nanorods were grown on Al2O3 (0001) substrates by using rf-associated molecular beam epitaxy. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected-area diffraction pattern (SADP) results showed that the (Ga1−xMnx)N nanorods had (0001) preferential orientations. XRD patterns showed that the (Ga1−xMnx)N nanorods contained a small number of grains with different preferred orientations. High-resolution TEM (HRTEM) images showed that the (Ga1−xMnx)N nanorods consisted of different preferentially oriented grains. The initial formation mechanisms for the (Ga1−xMnx)N nanorods grown on Al2O3 (0001) substrates are described on the basis of the XRD, the TEM, the SADP, and the HRTEM results.
The ultrastructure of nanoscale apatite biomimetically formed on an organic template from a supersaturated mineralizing solution was studied to examine the morphological and crystalline arrangement of mineral apatites. Needle-shaped apatite crystal plates with a size distribution of ∼100 to ∼1000 nm and the long axis parallel to the c axis () were randomly distributed in the mineral films. Between these randomly distributed needle-shaped apatite crystals, amorphous phases and apatite crystals (∼20–40 nm) with the normal of the grains quasi-perpendicular to the c axis were observed. These observations suggest that the apatite film is an interwoven structure of amorphous phases and apatite crystals with various orientations. The mechanisms underlying the shape of the crystalline apatite plate and aggregated apatite nodules are discussed from an energy-barrier point of view. The plate or needle-shaped apatite is favored in single-crystalline form, whereas the granular nodules are favored in the polycrystalline apatite aggregate. The similarity in shape in both single-crystalline needle-shaped apatite and polycrystalline granular apatite over a wide range of sizes is explained by the principle of similitude, in which the growth and shape are determined by the forces acting upon the surface area and the volume.
The Taiwan-America Occultation Survey (TAOS) aims to determine the number of small icy bodies in the outer reach of the Solar System by means of stellar occultation. An array of 4 robotic small (D=0.5 m), wide-field (f/1.9) telescopes have been installed at Lulin Observatory in Taiwan to simultaneously monitor some thousand of stars for such rare occultation events. Because a typical occultation event by a TNO a few km across will last for only a fraction of a second, fast photometry is necessary. A special CCD readout scheme has been devised to allow for stellar photometry taken a few times per second. Effective analysis pipelines have been developed to process stellar light curves and to correlate any possible flux changes among all telescopes. A few billion photometric measurements have been collected since the routine survey began in early 2005. Our preliminary result of a very low detection rate suggests a deficit of small TNOs down to a few km size, consistent with the extrapolation of some recent studies of larger (30–100 km) TNOs.
Magnetic resonance imaging (MRI) of the brain is the most important paraclinical diagnostic test in multiple sclerosis (MS). The appearance of MRI in Asians with MS is not well defined. We retrospectively surveyed the first brain and spinal cord MRI in patients diagnosed to have MS, according to Poser's criteria in seven regions throughout Asia to define the MRI changes among Asians with MS. There were 101 patients with first brain, and 86 with first spinal cord MRI, 66 of whom had both. The brain MRI showed a mean of 17 lesions per patient in T2 weighted images, mostly asymptomatic. Almost all the lesions were in the white matter, particularly in the juxtacortical, deep and periventricular white matter. A third of the lesions were greater than 5 mm, 14% enhanced with gadolinium. There were more supratentorial than infratentorial lesions at a ratio of 7.5: 1. Ninety five percent of the spinal cord lesions were in cervical and thoracic regions, 34% enhanced with gadolinium. The lesions extended over a mean of 3.6 ± 3.3 vertebral bodies in length. Fifty (50%) of the brain and 54 (63%) of the spinal MRI patients had the optic-spinal form of MS. The MRI of the optic-spinal and classical groups of patients were similar in appearance and distribution, except that the optic-spinal MS patients have fewer brain but longer and more severe spinal cord lesions. In conclusion, the brain and spinal cord MRI of Asian patients with MS was similar to that of the West, although, in this study, Asian MS patients had larger spinal cord lesions.
Sol-gel derived catalyst systems of cobalt, nickel, and iron were used in the growth of gallium nitride (GaN) nanowires by thermal chemical vapor deposition. A diffusion barrier matrix of titania (TiO2) has been used in which the catalysts were dispersed to have control of the catalyst particle sizes and hence on the size and morphology of the GaN nanowires. This single-step and cost-effective processing of the catalyst bed produced good-quality GaN naowires with comparable structural and optical properties with those previously reported. In a particular case, a stress-induced cubic admixture to the otherwise hexagonal structural symmetry was observed. The samples were characterized by high-resolution scanning electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and cathodo-luminescence studies.
We report soft X-ray spectra (4–18 nm) produced by the
interaction of 25–100-fs laser pulses at an intensity of up
to 7 × 1016 W/cm2 with a cryogenically
cooled Ar gas jet. New spectral lines from Ar8+,
Ar9+, and Ar10+ charge states appeared
with decreasing preexpansion gas temperature. A nonlinear increase
of X-ray line emission from Ar7+, Ar8+, and
Ar9+ was observed with cooling, which saturated below a
certain temperature. The drastic change in the spectrum is attributed
to efficient collisional heating and collisional ionization of growing,
small- to medium-sized (102–103 atoms) Ar
clusters from the cooled jet. When the laser pulse was extended from 25
to 100 fs we observed considerably stronger emission on lines from high
charge states, such as Ar8+, Ar9+, and
Ar10+, which suggests that the resonance absorption condition
could be reached for the 100-fs pulse.
The penultimate scene of Euripides' Troades, lines 1123–1250, presents the dressing of a child's corpse for burial. Even as the body is being carried away for interment, firebrands are seen on the heights of Troy (1256–9). All that remains is the commencement of the final burning of the city while the remaining Trojan captives are ordered off for embarkation and exile. The end of the play, therefore, enacts the annihilation of a city and its total abandonment; in such a context the funeral which immediately precedes surely makes a crucial contribution to the significance of the play and deserves close study.
The measurements of the desorption pressure-composition-temperature (P-C-T) of the TixZr1−xNiyV2−y (0 ≤ x ≤ 1,0 ≤ y ≤ 2) alloy have been investigated by means of a 32 factorial design method. The response surface function of hydrogen desorption between 0.01 and 10 atm was calculated by Yates' algorithm. Alloy with x = 0.35, y = 0.60 (i.e., Ti0.35Zr0.65Ni0.6V1.4) was found to possess maximum hydrogen desorption capacity. When examined by EDAX and SEM, this alloy shows three distinguishable phases and exhibits C14 structure. The effect of substitution of Mn and Ni for V was also studied. Alloy such as Ti0.35Zr0.65Ni1.2V0.4Mn0.4 has nearly a pure C14 structure with 89% hydrogen desorption ability. This alloy has 255 mAh/g, 231 mAh/g, and 210 mAh/g capacities at 25 mA/g, 50 mA/g, and 100 mA/g discharge rates, respectively. This indicates that the substitution of Mn and Ni for V not only can improve its hydrogen desorption ability, but also make the alloy structure more uniform and more suitable to be an electrode material.
Dielectric properties of polycrystalline BaTiO3 ceramics having grain sizes of 1 to 40 μm have been studied. Fine-grained ceramic BaTiO3 of 1 μm average grain size has 90°domains and has shown higher dielectric constant, lower ferroelectric transition temperature (Tc), and lower transition energy than coarser-grained material. 90°domain switching was preferentially produced in the fine-grained BaTiO3 as a result of abrasion. For the fine-grained BaTiO3, the dielectric constant decreased with one-dimensional pressure, whereas, for the coarse-grained material, the dielectric constant increased before decreasing with the pressure. The one-dimensional pressure resulted in increased Tc of both the fine- and coarse-grained BaTiO3, with the effect being the greatest for the coarse-grained material. The relationship between these results and internal stress, and the effect of external pressure imposed on internally stressed lattice, were discussed.