A tritan Waldo would be easier to detect in the periphery than a red/green one: evidence from visual search

In a color naming task from 0° to 55° eccentricity, we found that red/green performance (n=10 subjects) declines around 40° eccentricity, 5° earlier than does tritan performance (main effect of color, p=0.009; eccentricity, p<0.001; interaction, p=0.005). In a feature visual search task (e.g., red target dot among green distractor dots; twelve 2.5° diameter dots; 0, 20, and 45° eccentricity; 12 subjects), performance was significantly more impaired for red/green than for tritan stimuli, especially in the periphery (main effect of color, p=0.007; eccentricity, p<0.001; interaction, p=0.003). This effect occurred even following a rod bleach. Our results are consistent with influences from both the retina (especially random rather than selective peripheral cone input to midget ganglion cells for red/green perception, and selective cone input to small bistratified cells for tritan perception) and the cortex (differential cortical magnification across the two chromatic axes).     

Hydrogen sensing using gold nanoclusters supported on tungsten trioxide thin films

Controlled amounts of chemically synthesised gold (Au) nanoclusters were deposited onto tungsten trioxide (WO₃) nanostructured thin films as sensors for hydrogen. The Au/WO₃ thin films were characterised by XPS, XRD, SEM and TEM. Performance of Au/WO₃ films was tested at operating temperatures varying from room temperature to 450 °C. It was demonstrated that Au metal loading plays an important role in defining enhancement of the sensor response towards hydrogen. “Less is more” principle applies to the reported here sensors as materials made using lower concentration of Au nanoclusters demonstrated significantly better response. HRTEM images of the Au/WO₃ thin films provide evidence that the more active sensors are enriched with smaller Au nanoparticles (≤5 nm). Fast response towards H₂ within a wide range of industrially relevant concentrations, excellent baseline stability and signal reproducibility at optimized operating temperature demonstrate feasibility of this novel approach toward fabrication of sensors.     

Influence of walls on the migration of non-Brownian spherical particles in creeping flow: a lattice Boltzmann study

The influence of walls on binary encounters of spherical particles under creeping flow is studied by means of the lattice Boltzmann method. Depending on the initial particle displacement different behaviours can be observed, including the 'swapping' trajectories. The domain of the swapping trajectories is identified for interacting spheres with the same diameter; some preliminary results are given for the case of two spheres with different diameters. Finally, the influence of particle swapping on the dynamics of monodisperse suspensions is also described.     

Effect of oxygen addition on the water–gas shift reaction over Pt/CeO2 catalysts in microchannels – Results from catalyst testing and reactor performance in the kW scale

Wash-coated Pt/CeO₂, Pt/CeO₂/ZrO₂ and Pt/Cu/CeO₂ and Pt/CeO₂/Al₂O₃ based formulations were tested in sandwich type microreactors for water–gas shift (WGS) activity. At low reaction temperature of 260 °C, low conversion of carbon monoxide was initially observed which increased considerably upon the addition of air, a behaviour which was observed even after multiple cycles of start-up, operation with and without air and shut-down. At a higher reaction temperature of 400 °C air addition did not further improve the performance of the catalysts, which converted the carbon monoxide already close to equilibrium. One of the catalysts was incorporated into a larger reactor of kW scale and tested for its performance under conditions of WGS and oxygen enhanced WGS. The carbon monoxide conversion was increased by the air addition also on the larger reactor.     

Atom-to-atom interactions for atomic layer deposition of trimethylaluminum on Ga-rich GaAs(001)-4?×?6 and As-rich GaAs(001)-2?×?4 surfaces: a synchrotron radiation photoemission study

High-resolution synchrotron radiation photoemission was employed to study the effects of atomic-layer-deposited trimethylaluminum (TMA) and water on Ga-rich GaAs(001)-4 × 6 and As-rich GaAs(001)-2 × 4 surfaces. No high charge states were found in either As 3d or Ga 3d core-level spectra before and after the deposition of the precursors. TMA adsorption does not disrupt the GaAs surface structure. For the (4 × 6) surface, the TMA precursor existed in both chemisorbed and physisorbed forms. In the former, TMA has lost a methyl group and is bonded to the As of the As-Ga dimer. Upon water purge, the dimethylaluminum-As group was etched off, allowing the now exposed Ga to bond with oxygen. Water also changed the physisorbed TMA into the As-O-Al(CH₃)₂ configuration. This configuration was also found in 1 cycle of TMA and water exposure of the (2 × 4) surface, but with a greater strength, accounting for the high interface defect density in the mid-gap region.     

Recursive blind symbol estimation of convolutionally codedcochannel signals

A recursive blind equalizer is presented that directly estimates the transmitted symbols of multiple cochannel signals in the presence of ISI. The algorithm exploits shift structure present in the data model and the finite alphabet property of the signals. The proposed method possesses a separation property that allows the symbol sequences for each user to be estimated independently of the others. Problematic issues surrounding unknown and mismatched channel lengths for the cochannel users can be handled effectively in the recursive equalizer. Additionally, if the cochannel signals are encoded prior to transmission, we show how the code structure can be incorporated into the recursive equalizer to improve its performance