Learning, fatigue and preference formation in discrete choice experiments

While the repeated nature of Discrete Choice Experiments is advantageous from a sampling efficiency perspective, patterns of choice may differ across the tasks, due, in part, to learning and fatigue. Using probabilistic decision process models, we find in a field study that learning and fatigue behavior may only be exhibited by a small subset of respondents. Most respondents in our sample show preference and variance stability consistent with rational pre-existent andwell formed preferences. Nearly all of the remainder exhibit both learning and fatigue effects. An important aspect of our approach is that it enables learning and fatigue effects to be explored, even though they were not envisaged during survey design or data collection

The edge of the M87 halo and the kinematics of the diffuse light in the Virgo cluster core

We present high resolution FLAMES/VLT spectroscopy of intracluster planetary nebula (ICPN) candidates, targeting three new fields in the Virgo cluster core with surface brightness down to mu_B = 28.5. Based on the projected phase space information we separate the old and 12 newly-confirmed PNs into galaxy and intracluster components. The M87 PNs are confined to the extended stellar envelope of M87, within a projected radius of ~ 160 kpc, while the ICPNs are scattered across the whole surveyed region between M87 and M86. The velocity dispersions determined from the M87 PNs at projected radii of 60 kpc and 144 kpc show that the galaxy's velocity dispersion profile decreases in the outer halo, down to 78 +/- 25 km/s. A Jeans model for the M87 halo stars in the gravitational potential traced by the X-ray emission fits the observed velocity dispersion profile only if the stellar orbits are strongly radially anisotropic (beta ~= 0.4 at r ~= 10 kpc increasing to 0.8 at the outer edge), and if additionally the stellar halo is truncated at ~= 150 kpc average elliptical radius. From the spatial and velocity distribution of the ICPNs we infer that M87 and M86 are falling towards each other and that we may be observing them just before the first close pass. The inferred luminosity-specific PN numbers for the M87 halo and the ICL are in the range of values observed for old (> 10 Gyr) stellar populations (abridged).Comment: Accepted for publication in Astronomy and Astrophysics. 16 pages, 14 figures and 4 table

Corrosion of Aluminum in Alkaline Solutions

Aluminum has been an important member of the metal group since its isolation about 100 years ago. It has sprung into prominence in the commercial field and in household use in the last thirty years. The metal is light, possesses good thermal and electrical conductivity and as an alloy with other metals takes on a surprising degree of strength. The problem of producing aluminum cheaply enough to make it practical has finally been overcome to a great extent. It now remains to be seen just what further uses there are to which this new metal may be put. Aluminum may be hardened and strengthened by addition of other metals but the attack which it suffers from acids and alkalines is a major shortcoming. Many experiments have been carried out to reveal methods by which corrosion o-r aluminum may be minimized. Some of these methods are practical while others are not. However, the problem of coping with the greatest problem in metallurgy appealed to the author to such an extent that he has tended his efforts toward the general information which experimental corrosion may afford. From this information, certain conclusions can be drawn which may be of value in facing the corrosion problem