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The region of permanent densification beneath a Berkovich indentation imprint in silica glass is investigated using a novel chemical dissolution technique. The use of the similitude regime in sharp indentation testing allows one to record reliable data with a good spatial resolution that makes it possible to deal with low loads (typically below 10 mN) and crack-free imprints. The densified zone dissolves much quicker than the non densified regions. The analysis of the results, along the vertical axis, indicates that the densification zone is rather homogeneous with a steep transition to the non densified zone. The size of the densification zone, with respect to the initial free surface, is estimated to be around 1.9 the maximum penetration depth of the instrumented indentation test. These findings are compared with former experimental data and critically compared with the results of numerical simulations from selected constitutive equations and other numerical techniques from the literature. These comparisons highlight some advantages and disadvantages of existing modelings and thus call for further advanced progress on that matter. They nevertheless favor mostly the contribution of the densification process with respect to the plastic flow (volume conservative process) in creating a permanent imprint., Comment: submitted paper

Abnormal grain growth (AGG) was observed in rutile TiO2 formed by the thermal treatment of anatase TiO2 in the presence of zirconium silicate. This morphological behaviour was seen to occur in sintered powder compacts and thin films with solid state zircon dopants and in TiO2 coatings on grains of zircon sand. In order to clarify the mechanism of AGG in this system, various doping methods were employed and the morphological consequences of these doping methods were investigated. It was found that doping by Zr and Si does not give rise to abnormal grain growth. The observed phenomena were discussed in terms of morphological and energetic considerations. It is likely that a distinct orientation relationship between rutile TiO2 and ZrSiO4 and possible grain boundary liquid formation play a role in giving rise to the rapid growth of faceted prismatic rutile.

We present a method to simulate color, 3-dimensional images taken with a space-based observatory by building off of the established shapelets pipeline. The simulated galaxies exhibit complex morphologies, which are realistically correlated between, and include, known redshifts. The simulations are created using galaxies from the 4 optical and near-infrared bands (B, V, i and z) of the Hubble Ultra Deep Field (UDF) as a basis set to model morphologies and redshift. We include observational effects such as sky noise and pixelization and can add astronomical signals of interest such as weak gravitational lensing. The realism of the simulations is demonstrated by comparing their morphologies to the original UDF galaxies and by comparing their distribution of ellipticities as a function of redshift and magnitude to wider HST COSMOS data. These simulations have already been useful for calibrating multicolor image analysis techniques and for better optimizing the design of proposed space telescopes., Comment: 14 pages, 15 figures, accepted to Astroparticle Physics

We monitored 13 moderate luminosity active galactic nuclei at z=0.36 to measure flux variability, explore feasibility of reverberation mapping, and determine uncertainties on estimating black hole mass from single-epoch data. Spectra and images were obtained with approximately weekly cadence for up to 4 months, using the KAST spectrograph on the 3-m Shane Telescope. In broad band we detect peak-to-peak variations of 9-37% and rms variations of 2-10%. The observed flux variability in the g' band (rest-frame 2800-4000\AA) is consistent with that in the r' band (rest-frame 4000-5200\AA), but with larger amplitude. However, after correcting for stellar light dilution, using Hubble Space Telescope images, we find nuclear variability of 3-24% (rms variation) with similar amplitudes in the g' and r' bands within the errors. Intrinsic flux variability of the H$\beta$ line is also detected at the 3-13% level, after accounting for systematic errors on the spectrophotometry. This demonstrates that a reverberation mapping campaign beyond the local universe can be carried out with a 3-m class telescope, provided that sufficiently long light curves are obtained. Finally, we compare the H$\beta$ FWHM measured from mean spectra with that measured from single-epoch data, and find no bias but an rms scatter of 14%, mostly accounted for by the uncertainty on FWHM measurements. The propagated uncertainty on black hole mass estimates, due to the FWHM measurement errors using low S/N (10--15 per pixel) single-epoch spectra, is 30%., Comment: 12 pages, 7 figures, accepted by ApJ