The influence of cell window imperfections on the calibration and measured data of two types of rotating-analyzer ellipsometers

A graphical method has been developed to determine the plane of incidence in the presence of cell windows with small retardation. For two types of rotating-analyzer ellipsometers, expressions have been derived that relate the experimental parameters and the elements of the Mueller imperfection matrices of the windows. These matrices can be determined by measuring with and without cell windows. Measurements have been performed with three samples with different optical constants

How are coastal benthos fed?

Water movement can influence the distribution of benthos, in part, by increasing food delivery; however, the impact of advective transport and turbulent diffusion on organic matter flux to nearshore benthic communities is not well quantified. In this study, we measured the vertical particulate organic carbon (POC) and particulate phosphorus (PP) flux in nearshore Lake Michigan using two naturally occurring daughter/parent radionuclide pairs (234Th/238U and 90Y/90Sr) and compared these fluxes to coincident benthic chamber estimates of respiration and total phosphorus efflux by quagga mussels on the lakebed. We found that advective onshore transport and vertical convective mixing increased POC and PP flux to the nearshore benthos by a factor of ~15 and ~30 over offshore trap-derived estimates of flux. From these results, we hypothesize that high benthos population densities are related to an edge effect created when the dominant mechanism of particle delivery transitions from gravitational settling to convection

How can ten fingers shape a pot? Evidence for equivalent function in culturally distinct motor skills

Behavioural variability is likely to emerge when a particular task is performed in different cultural settings, assuming that part of human motor behaviour is influenced by culture. In analysing motor behaviour it is useful to distinguish how the action is performed from the result achieved. Does cultural environment lead to specific cultural motor skills? Are there differences between cultures both in the skills themselves and in the corresponding outcomes? Here we analyse the skill of pottery wheel-throwing in French and Indian cultural environments. Our specific goal was to examine the ability of expert potters from distinct cultural settings to reproduce a common model shape (a sphere). The operational aspects of motor performance were captured through the analysis of the hand positions used by the potters during the fashioning process. In parallel, the outcomes were captured by the geometrical characteristics of the vessels produced. As expected, results revealed a cultural influence on the operational aspects of the potters' motor skill. Yet, the marked cultural differences in hand positions used did not give rise to noticeable differences in the shapes of the vessels produced. Hence, for the simple model form studied, the culturally-specific motor traditions of the French and Indian potters gave rise to an equivalent outcome, that is shape uniformity. Further work is needed to test whether such equivalence is also observed in more complex ceramic shapes

Interaction of oxygen with an AISI 314 stainless steel surface studied by ellipsometry and auger electron spectroscopy in combination with ion bombardment

The influence of pretreatment (ion bombardment) on the initial oxidation of AISI 314 stainless steel has been investigated in ultra high vacuum systems with ellipsometry and Auger electron spectroscopy. The bombardment was carried out with Ar+ ions with energies up to 2.2 keV at various doses and angles of incidence. Oxidation was performed at low Pos (< 10−5 Torr) and sample temperatures (<300°C). The worked layer was removed with low-energy argon ions. High energy bombardment causes an increase in oxidation rate and higher values of the real and imaginary part of the refractive index as compared to the undisturbed sample. The rate and extent of oxidation increases with increasing energy, dose and angle of incidence of the ion beam. The outermost part of the oxide is enriched in iron while the region near the substrate contains more nickel and chromium