Transition from diffusive to ballistic capture related to hydrogen incorporation in amorphous silicon

Three intersection mechanisms with the gliding planes (111)_TB, (001)_TB and (115)_TB respectively have been observed by high-resolution electron microscopy in the type-I twin intersection of gamma-TiAl. It was found that the intersection mechanism that occurred was related to the thickness of the incident twin. The accommodation mechanism on the (111)_TB atomic plane is preferred when the incident twin becomes very thin. The dislocation dissociations of the (111)_TB plane accommodation are the most energetically unfavourable of the dissociations of the three intersection mechanisms; however, the resultant dislocations on the (111)_TB planes are the easiest to propagate away from the intersection area. Accordingly, (111)_TB atomic plane accommodation is considered to be the only mechanism allowing shear transmission under the small local stress of the pile-up of the incident twinning partials.     

EXPERIMENTER CALCULATION ERRORS: A POTENTIAL FACTOR AFFECTING INTERPRETATION OF RESULTS1

Following a study of socially withdrawn children, it was noted that checks of experimenter calculations indicated discrepancies. The present study investigated the magnitude and direction of experimenter errors in data computations. Two full-time research assistants, who served as experimenters, processed the behavioral observation data. These experimenters were referred to as the subjects in this study. Standard data values, against which the subjects' computations were compared, were established by two other research assistants and a computer staff. The results indicated that experimenters' original data values disagreed with the standard data values. The daily errors showed considerable variability for both experimenters. The specific factors accounting for this variability could not be identified, although frequency of experimenter responses required to obtain rate and duration data, time spent calculating, and complexity of task were suggested as possible contributing variables. While disagreements occurred across all experimental days, the magnitude of differences was generally small. An examination of direction of differences in both experimenters' data showed no systematic trends in favor of the experimental hypothesis. Rather, there appeared to be a trend in the other direction. This study suggests that the same research decisions would have been made during the original investigation using either set of data.     

Structure of twins in GaAs nanowires grown by the vapour–liquid–solid process

Semiconducting crystalline materials that are poor conductors of heat are important as thermoelectric materials and for technological applications involving thermal management. A combination of neutron scattering, lowtemperature ultrasonic attenuation and thermal conductivity measurements are reported on single crystals of the semiconductors Sr₈Ga₁₆Ge₃₀ and Ba₈Ga₁₆Ge₃₀. Taken together, these measurements suggest specific structural features that result in a crystal with the lowest possible thermal conductivity, namely that of a glass with the same chemical composition. Weakly bound atoms that 'rattle' within oversized atomic cages in a crystal result in a low thermal conductivity, but the present data show that both 'rattling' atoms and tunnelling states are necessary to produce a true glass-like thermal conductivity.     

Many-body potential for nitrogen in α-iron

N atom is one of the most frequent foreign interstitial atoms in α-iron along with C atoms. The Fe–C potential has been well-developed and can reproduce many significant interactions of C with point defects present in α-iron. However, there exists no satisfactory Fe–N potential to describe the interactions of N with point defects. Here, we develop a many-body potential for N in α-iron. The potential parameters are determined by fitting to ab initio data, which includes energetics, configurations, and relaxations of Fe atoms close to N atom. This potential successfully describes the interactions of Fe–N across a wide range of defect environments. The potential employs the embedded atom method form and hence is appropriate for large-scale molecular dynamics simulation.     

Energetic effects of dopants on the eutectoid decomposition of Nb–Si in situ composites

The influences of doping elements (Ti, Zr, Hf, V, Ta, Cr, Mo, W and Al) on the heats of formation of Nb, Nb₅Si₃ and Nb₃Si have been studied using first-principles pseudopotential plane-wave method based on density functional theory. Site preferences of dopants in Nb₅Si₃ and Nb₃Si intermetallics are first determined by comparing the heats of formation of the systems with different site occupations of the doping atoms. The partitionings of dopants between the equilibrium phases Nb and Nb₅Si₃ of Nb–Si in situ composites are then discussed and compared with experimental results. Phase partitioning behaviours of the alloying elements are found to depend strongly on the number of their valence electrons. By calculating the enthalpy of reaction regarding the eutectoid decomposition of Nb₃Si phase, we conclude that Ta is a Nb₃Si stabiliser while other dopants destabilise Nb₃Si at the investigated concentration.     

Investigations of the magnetic,mechanical and thermodynamic properties of cubic phase LaMO3 (M=Ti~Fe)

The magnetic, mechanical and thermodynamic properties of LaMO₃ (M = Ti~Fe) have been systematically investigated using the first-principles calculations. The total magnetic moments of LaMO₃ are mainly from the M atom, and the contributions from La and O are very small. For LaTiO₃, LaVO₃, LaCrO₃ and LaMnO₃ the total magnetic moments agree well with experiment, while with somewhat larger disagreement for LaFeO₃. Using the GGA + U (U = 5.6 eV), the calculated magnetic moment of LaFeO₃ is 4.98μ_B, which is in agreement with experiment data. The elastic constants and Vickers hardness suggest that LaMO₃ are mechanically stable and soft materials. The B/G ratios indicate that all of LaMO₃ are ductile except LaVO₃ and LaCrO₃.The LaCrO₃ has the highest Debye temperature, while LaVO₃ has the lowest Debye temperature.     

Bayes Factors Have Frequency Properties—This Should Not Be Ignored: A Rejoinder to Morey,Wagenmakers, and Rouder

Hoijtink, van Kooten, and Hulsker (2016 Hoijtink, H., van Kooten, P., &; Hulsker, K. (2016). Why Bayesian psychologists should change the way they used the Bayes factor. Multivariate Behavioral Research, 51, 1--9. doi: 10.1080/00273171.2014.969364.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) outline a research agenda for Bayesian psychologists: evaluate and use the frequency properties of Bayes factors. Morey, Wagenmakers, and Rouder (2016 Morey, R. D., Wagenmakers, E. -J., &; Rouder, J. N. (2016). Calibrated Bayes factors should not be used: A reply to Hoijtink, van Kooten, and Hulsker. Multivariate Behavioral Research, 51, 10--17. doi: 10.1080/00273171.2015.1052710.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) respond that Bayes factors calibrated using frequency properties should not be used. This paper contains the response of Hoijtink, van Kooten, and Hulsker to the criticism of Morey, Wagenmakers, and Rouder (2016 Morey, R. D., Wagenmakers, E. -J., &; Rouder, J. N. (2016). Calibrated Bayes factors should not be used: A reply to Hoijtink, van Kooten, and Hulsker. Multivariate Behavioral Research, 51, 10--17. doi: 10.1080/00273171.2015.1052710.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]).