Differences in the micromechanical properties of dendrites and interdendritic regions in superalloys

Statistical analysis of white-light interferometry (WLI) experiments performed on Ni-based single-crystal superalloys (SX) have revealed a different height distribution between the dendritic cores (DCs) and the interdendritic regions (IRs) of the polished samples. The micromechanical property difference is largely ascribed to the uneven distribution of the alloying elements. In this context, possible reasons for this difference are discussed by comparing with different experiment results obtained by previous researchers, and a proposal forecasting the hardness ratio of IRs/DCs is put forward.     

Resurgence is greater following a return to the training context than remaining in the extinction context

The present study examined whether resurgence of a previously reinforced target response upon removing alternative reinforcement would be greater when (1) returning to the original training context (ABA context changes) versus (2) remaining in the analogue treatment context in which the alternative response was differentially reinforced (ABB context changes). Experiment 1 arranged reinforcement of button pressing with points exchangeable for money in university students. Experiment 2 arranged reinforcement of lever pressing with food for rats. Experiment 3 arranged reinforcement of responses to a touchscreen with small bites of food with children diagnosed with ASD. Overall, resurgence of target responding tended to be greater when returning to the original training context (A) than when remaining in the analogue treatment context (B). These findings suggest context changes with differential reinforcement treatments could exacerbate the recurrence of problem behavior resulting from reductions in treatment integrity through failure to reinforce appropriate behavior.     

Effect of pressure on the mechanical and dynamical stability of NaAlSi

The effects of pressure on the mechanical and dynamical stability of NaAlSi have been fully investigated by first-principles calculations within the generalised gradient approximation (GGA). The obtained results show that the optimised lattice constants, atomic positions and elastic constants at ambient pressure are in good agreement with the available experimental and theoretical data. The lattice constants decrease monotonically with increasing pressure. The elastic constant C₁₁, C₁₂, C₁₃, C₃₃ and C₆₆ increase while C₄₄ decreases with increasing pressure. It is found that NaAlSi is mechanically unstable when the pressure is above 25.97?GPa. The phonon-dispersion curves along several high symmetry lines are obtained. The phonon frequencies at the Z point decrease with increasing pressure and completely soften to zero at 27.52?GPa, further confirming the structural instability of NaAlSi.     

Practicing Community Psychology Through Mixed Methods Participatory Research Designs

Community psychologists address social inequalities and problems by employing ecological principles, multiple methodologies, and participatory approaches to empower individuals, organizations, and communities to organize action and systems change. This article aims to contribute to mixed methods literature by presenting three models of mixed methods participatory research across a variety of geographic and sociocultural contexts. The models outline participatory processes and points of qualitative and quantitative data integration. Challenges related to the interplay between participatory approaches and mixed methods studies as well as implications on social science research are discussed.     

New polytypes of long-period stacking ordered structures in a near-equilibrium Mg97Zn1Y2 alloy

By atomic-scale high-angle annular dark-field scanning transmission electron microscopy, the long-period stacking ordered (LPSO) structures in a near-equilibrium Mg₉₇Zn₁Y₂ (at.%) alloy have been characterised. In addition to 18R and 14H, new polytypes of LPSO structures are analysed and determined as 60R, 78R, 26H, 96R, 38H, 40H, 108H and 246R. All of these LPSO structures feature AB′C′A building blocks with two Mg layers and three Mg layers sandwiched between them. The Bravais lattices and space groups of new polytypes of LPSO structures were easily determined via the newly introduced method. A structural relationship between the LPSOs is proposed.     

Leverpress Escape/Avoidance Training Increases Neurotrophin Levels in Rat Brain

In addition to their well-known role in neural development, the neurotrophins BDNF and NGF help mediate the plasticity that occurs in the brain to promote learning. Exposure to learning procedures often leads to increases in neurotrophins, while exposure to stress often results in decreases. It is unclear how the neurotrophins would respond to an aversive learning task. Therefore, BDNF and NGF content in the dorsal striatum, hippocampus, and basal forebrain was measured following discrete trial lever-press escape/avoidance conditioning. Conditioning significantly increased levels of both neurotrophins in hippocampus and basal forebrain, relative to home cage controls (HCC). Contrary to expectations, the dorsal striatum did not show any significant changes. However, significant correlations were observed between dorsal striatal neurotrophins and aspects of avoidance performance. This may indicate that the dorsal striatum is involved in the performance aspects of the task. Results are discussed in terms of the role of neurotrophins in the acquisition of new information, and the neural structures involved in different types of memory.