Long-Wavelength Excesses in Two Highly Obscured High-Mass X-Ray Binaries: IGR J16318–4848 and GX 301–2

We present evidence for excess long-wavelength emission from two high-mass X-ray binaries, IGR J16318-4848 and GX 301-2, that show enormous obscuration (N_H ≃ 10^(23)-10^(24) cm^(-2)) in their X-ray spectra. Using archival near- and mid-infrared data, we show that the spectral energy distributions of IGR J16318-4848 and GX 301-2 are substantially higher in the mid-infrared than their expected stellar emission. We successfully fit the excesses with ~1000 K blackbodies, which suggests that they are due to warm circumstellar dust that also gives rise to the X-ray absorption. However, we need further observations to constrain the detailed properties of the excesses. This discovery highlights the importance of mid-infrared observations for understanding highly obscured X-ray binaries

Orbital-selective Mass Enhancements in Multi-band Ca2−x_{2-x}Srx_{x}RuO4_{4} Systems Analyzed by the Extended Drude Model

We investigated optical spectra of quasi-two-dimensional multi-band Ca$_{2-x}$Sr$_{x}$RuO$_{4}$ systems. The extended Drude model analysis on the ab-plane optical conductivity spectra indicates that the effective mass should be enhanced near $x=0.5$. Based on the sum rule argument, we showed that the orbital-selective Mott-gap opening for the $d_{yz/zx}$ bands, the widely investigated picture, could not be the origin of the mass enhancement. We exploited the multi-band effects in the extended Drude model analysis, and demonstrated that the intriguing heavy mass state near $x=0.5$ should come from the renormalization of the $d_{xy}$ band.Comment: 4 figure

Dislocation Velocity in Single and Polycrystalline Silicon Iron

The stress dependence of screw dislocation velocity single and polycrystalline specimens of an iron-3.14% silicon alloy was measured by observation of slip band growth. An electrolytic etching technique was used to reveal dislocation intersections with the specimen surface, and slip bands were observed to form from fresh scratches and from grain boundaries as a result of pulse loading. Screw dislocation velocity on the {110} 〈111〉system in single crystals at room temperature followed the relation ν = (τ/τ_0)^n where n = 30.1. A plot of screw dislocation velocity vs. nominal resolved shear stress in individual grains of polycrystalline specimens shows considerable scatter which is attributed to the effects of stress variations due to elastic anisotropy. Observation of slip band growth in scratched and unscratched grains indicates that the stress required to activate grain boundary sources is greater than the stress required to propagate fresh dislocations

The initiation of yielding in silicon-iron

An experimental program was conducted in which the etch pit technique was used for the direct observation of dislocation configurations at various stages of yielding. Poly-crystalline tensile specimens of 3 per cent silicon-iron were loaded in tension at constant strain rate and by load pulses. A new model of the delay-time for yielding at constant applied stress is presented. Three assumptions used are (a) no dislocation motion occurs below a critical resolved shear stress, (b) the yielding rate is dependent upon the velocity of mobile dislocations, and (c) the end of the delay period occurs when yielding of the grains has spread continuously through the thickness of the specimen. This model is consistent with the experimental observations and explains the true static upper yield point and the shape of the strain vs. time curve at constant applied stress. The model also yields reasonable values for the stress concentration factor on grains in the critical cross-section that are least favorably oriented for slip

Dislocation velocity in single and polycrystalline silicon-iron

The stress dependence of screw-dislocation velocity in single and polycrystalline specimens of an iron-3.14% silicon alloy was measured by observation of slip-band growth. An electrolytic etching technique was used to reveal dislocation intersections with the specimen surface, and slip bands were observed to form from fresh scratches and from grain boundaries as a result of pulse loading. Screw dislocation velocity on the {110} 111 system in single crystals at room temperature followed the relation ΰ = (τ/τ0)n, where n = 30.1. A plot of screw-dislocation velocity vs nominal resolved shear stress in individual grains of polycrystalline specimens shows considerable scatter which is attributed to the effects of stress variations due to elastic anisotropy. Observation of slip-band growth in scatched and unscratched grains indicates that the stress required to activate grain boundary sources is greater than the stress required to propagate fresh dislocations