Length summation in noise

To investigate the effect of background noise on visual summation, we measured the contrast detection thresholds for targets with or without a white noise mask in luminance contrast. The targets were Gabor patterns placed at 3° eccentricity to either the left or right of the fixation and elongated along an arc of the same radius to ensure equidistance from fixation for every point along the long axis. The task was a spatial two-alternative forced-choice (2AFC) paradigm in which the observer had to indicate whether the target was on the left or the right of the fixation. The threshold was measured at 75% accuracy with a staircase procedure. The detection threshold decreased with target length with slope −1/2 on log-log coordinates for target lengths between 30′ and 300′ half-height full-width (HHFW), defining a range of ideal matched-filter summation extending up to about 200′ (or about 16× the center width of the Gabor targets). The summation curves for different noise contrasts were shifted copies of each other. For the threshold versus mask contrast (TvN) functions, the target threshold was constant for noise levels up to about −22 dB, then increased with noise contrast to a linear asymptote on log-log coordinates. Since the “elbow” of the target threshold versus noise function is an index of the level of the equivalent noise experienced by the visual system during target detection, our results suggest that the signal-to-noise ratio was invariant with target length. We further show that a linear-nonlinear-linear gain-control model can fully account for these results with far fewer parameters than a matched-filter model

Modified theory for cavity perturbation measurement of plasma parameters

Cavity perturbation measurement of plasma parameter

Evolution of superconductivity by oxygen annealing in FeTe0.8S0.2

Oxygen annealing dramatically improved the superconducting properties of solid-state-reacted FeTe0.8S0.2, which showed only a broad onset of superconducting transition just after the synthesis. The zero resistivity appeared and reached 8.5 K by the oxygen annealing at 200\degree C. The superconducting volume fraction was also enhanced from 0 to almost 100%. The lattice constants were compressed by the oxygen annealing, indicating that the evolution of bulk superconductivity in FeTe0.8S0.2 was correlated to the shrinkage of lattice.Comment: 13 pages, 6 figure

Peptide Mimicrying Between SARS Coronavirus Spike Protein and Human Proteins Reacts with SARS Patient Serum

Molecular mimicry, defined as similar structures shared by molecules from dissimilar genes or proteins, is a general strategy used by pathogens to infect host cells. Severe acute respiratory syndrome (SARS) is a new human respiratory infectious disease caused by SARS coronavirus (SARS-CoV). The spike (S) protein of SARS-CoV plays an important role in the virus entry into a cell. In this study, eleven synthetic peptides from the S protein were selected based on its sequence homology with human proteins. Two of the peptides D07 (residues 927–937) and D08 (residues 942–951) were recognized by the sera of SARS patients. Murine hyperimmune sera against these peptides bound to proteins of human lung epithelial cells A549. Another peptide D10 (residues 490–502) stimulated A549 to proliferate and secrete IL-8. The present results suggest that the selected S protein regions, which share sequence homology with human proteins, may play important roles in SARS-CoV infection

Composite diamond-like carbon and silicon carbide tips grown on oblique-cut Si(111) substrates

[[abstract]]A diamond-like carbon (DLC) and silicon carbide (SiC) composite tip structure was successfully deposited on an oblique-cut Si(111) substrate of terrace width less than 21.1 Å. The DLC morphology depended on the Si(111) terrace width in the oblique-cut Si(111) surface. A continuous and dense DLC film started to form on the Si(111) substrate of terrace width higher than 27.8 Å. The density of the DLC/SiC composite tip also depended on the terrace width. The DLC films on the Si(111) with or without oblique cut had about the same Raman characteristics regardless of their different morphologies. The formation mechanism of the DLC/SiC tip structure was discussed. ©2001 American Institute of Physics.[[fileno]]2010137010057[[department]]物理

Effects of Zeeman spin splitting on the modular symmetry in the quantum Hall effect

Magnetic-field-induced phase transitions in the integer quantum Hall effect are studied under the formation of paired Landau bands arising from Zeeman spin splitting. By investigating features of modular symmetry, we showed that modifications to the particle-hole transformation should be considered under the coupling between the paired Landau bands. Our study indicates that such a transformation should be modified either when the Zeeman gap is much smaller than the cyclotron gap, or when these two gaps are comparable.Comment: 8 pages, 4 figure

Alloy Design for High-Entropy Bulk Glassy Alloys

AbstractAn efficient alloy design for bulk metallic glasses (BMGs) assisted by a composition–configurational entropy (C-CE) diagram has been proposed by introducing a feature of high-entropy (HE) alloys that are defined by an equi-atomic alloy with five or more elements. The proposed alloy design compensated for a shortcoming in determining the compositions of BMGs and led to success in forming a Pd20Pt20Cu20Ni20P20 HE-BMG with a maximum diameter of 10mm. The C-CE diagram demonstrates the equi-atomicity of alloys, providing candidates for HE-BMGs. The alloy design for HE-BMG will promise opening up the new cutting-edge in both HE alloys and BMGs