Deformed substructures in fine-grained tetragonal zirconia

Transmission electron microscopy (TEM) has been employed to examine the deformed microstructures of a high-purity tetragonal zirconia polycrystal containing 3mol% yttria. The TEM observations reveal that piled-up and tangled dislocations are developed within grains at a high stress, but such substructures do not appear at a lower stress, except for a small number of isolated dislocations. The stress-dependent deformed microstructures suggest that the dislocation substructures observed at a high stress are not due to any experimental artefacts. Applying a model proposed by Eshelby et al. to the observed pile-up dislocations, it can be estimated that a stress concentration of the order of 14-25 is generated around multiple-grain junctions during deformation.     

Application of the stagnant stage concept for monitoring Mn partitioning at the austenite-ferrite interface in the intercritical region for Fe–Mn–C alloys

The length of the stagnant stage during the new ferrite growth starting from a mixture of austenite and ferrite has been investigated for a Fe-0.17Mn-0.023C (wt%) alloy. It was found that the stagnant stage depends on the thermal path followed to create the mixture, and deduce that the tie-lines for austenite to ferrite transformation are quite different from those for ferrite to austenite transformation. The length of the stagnant stage is determined by the very local partitioning effect at the interface, and it can be used as a tool to monitor the Mn partitioning.     

Precipitation in a Cu–4Ti–2Be alloy

It is known that the binary Cu–2?wt.% Be alloy can be strengthened by ageing its supersaturated solution at 523?K. The increase in the strength arising from ageing is because of the formation of GP zones. The same level of strength is achieved by ageing the supersaturated solid solution of a dilute binary Cu–4?wt.% Ti alloy at 723?K. In contrast to Cu–2?wt.% Be alloy, the increase in strength in this alloy occurs on account of spinodal decomposition of the as-quenched microstructure through the mechanism of clustering and ordering. In the present study, decomposition of a supersaturated solid solution of the ternary Cu–4?wt.% Ti–2?wt.% Be alloy was studied. Whereas ageing of this alloy at 523?K resulted in the formation of GP zones like in a Cu–2?wt.% Be alloy, ageing at 723?K resulted in a spinodally decomposed microstructure as in a Cu–4?wt.% Ti alloy. The decomposition of the ternary alloy at the two temperatures by two different mechanisms indicates that Be and Ti in solution in Cu act, more or less, independently of each other during ageing.     

Self-assembly-assisted growth of two-dimensional Penrose tiling

An algorithm for the growth of two-dimensional Penrose tiling, based on symmetry operations on a seed rhombus, is discussed and demonstrated. Independent of empirical matching rules, as suggested by Penrose [Bull. Inst. Math. Appl. 10 266 (1974)], and also overcoming the scaling-down operation, as proposed by Ramachandrarao et al. (Acta Crystallogr. A 47 210 (1991)], the present algorithm follows a mechanism akin to self-assembly and can be continued ad infinitum.     

Embedding irony and the semantics/pragmatics distinction

This paper argues that we need to re-think the semantics/pragmatics distinction in the light of new evidence from embedding of irony. This raises a new version of the old problem of ‘embedded implicatures’. I argue that embedded irony isn’t fully explained by solutions proposed for other embedded implicatures. I first consider two strategies: weak pragmatics and strong pragmatics. These explain embedded irony as truth-conditional content. However, by trying to shoehorn irony into said-content, they raise problems of their own. I conclude by considering how a modified Gricean model can explain that irony embeds qua implicature. This leads us to prefer a local implicature model. This has important consequences for how we draw the semantics/pragmatics distinction.     

Eye-Hand Coordination in Rhythmical Pointing

The authors investigated the relation between hand kinematics and eye movements in 2 variants of a rhythmical Fitts's task in which eye movements were necessary or not necessary. P. M. Fitts's (1954) law held in both conditions with similar slope and marginal differences in hand-kinematic patterns and movement continuity. Movement continuity and eye—hand synchronization were more directly related to movement time than to task index of difficulty. When movement time was decreased to fewer than 350 ms, eye—hand synchronization switched from continuous monitoring to intermittent control. The 1:1 frequency ratio with stable π/6 relative phase changed for 1:3 and 1:5 frequency ratios with less stable phase relations. The authors conclude that eye and hand movements in a rhythmical Fitts's task are dynamically synchronized to produce the best behavioral performance.     

Mass Perturbation of a Body Segment: 2. Effects on Interlimb Coordination

The shifts in relative phase that are observed when rhythmically coordinated limbs are submitted to asymmetric mass perturbations have typically been attributed to the induced eigenfrequency difference ($DL$oM) between the limbs. Modeling the moving limbs as forced linear oscillators, however, reveals that asymmetric mass perturbations may induce a difference not only in eigenfrequency (i.e., $DL$oM $$ 0) but also in the covarying low-frequency control gains (i.e., $DLk $$ 0). Because the inverse of the lowfrequency control gain (k) reflects the level of muscular torque (input) required for a particular displacement from equilibrium (output), asymmetric mass perturbations may result in an imbalance in the muscular torques required for task performance (related to $DLk $$ 0). Thus, it is possible that the effects attributed to $DL$oM were in fact mediated by $DLk. In 2 experiments, the authors manipulated $DLk and $DL$oM separately by applying mass perturbations to the lower legs of 9 participants. The relative phasing between the legs was not affected by $DLk, but manipulation of $DL$oM (while $DLk remained approximately 0) induced systematic relative phase shifts that were more pronounced for antiphase than for in-phase coordination. That indication that the coordination dynamics is indeed influenced by an imbalance in eigenfrequency is discussed vis-à-vis the question of how such a merely peripheral property may affect the underlying coordination process.     

Psychophysics of Kinesthesis

A horizontal straight-arm movement was used to determine the relationship between the physical stimulus continuum and the psychological continuum of kinesthetic extent of arm movement. A power function with an exponent of 1.075 best described this relationship. In addition, to classify extent of movement as belonging to either a prothetic or metathetic continuum, the category scale was derived. According to the functional criteria described by Stevens (1957), extent of movement was subserved by a metathetic process which would indicate that, for the present task, judgments were made through the use of positional cues rather than amplitude cues.     

Signs in their times: introducing a review symposium on Robert Yelle's Semiotics of Religion

This essay introduces a review symposium on Robert Yelle's Semiotics of Religion: Signs of the Sacred in History (2013). It first reviews the book's argument, then offers a selective review of the six contributions to the symposium, along with aspects of Yelle's responses to these.