Quasistatic yielding of crystalline solids

Mar 31, 2021

When a crystalline solid is slowly deformed, it encounters an equilibrium first order transition that breaks lattice translation symmetry and releases stress by lattice slip. We show that this transition, which occurs at infinitesimal deformation, may be viewed as a condensation of a specific linear combination of elastic displacements known as a non-affine mode; this is the order parameter for the transition. Auxiliary tensor fields are necessary to render spatial gradients of the order parameter, and therefore the free energy density, lattice translation invariant. Interfaces necessarily contain contributions from both order parameter gradients and dislocations, which arise naturally from spatial derivatives of the auxiliary fields. [In progress].

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Unified citation parameters for journals and individuals: Beyond the Journal Impact Factor or \(h\)-index alone

Sep 10, 2021

We seek a unified and distinctive citation description of both journals and individuals. The Journal Impact Factor has a restrictive definition that constrains its extension to individuals, whereas the \(h\)-index for individuals can easily be applied to journals. Going beyond a single parameter, the shape of each negative-slope Hirsch curve of citations versus rank is a distinctive citation profile. This shape can be described through five minimal parameters or "flags": the \(h\)-index itself on the curve; the average citation of each segment on either side of \(h\); and the two axis intercepts. We obtain the five flags from data for journals and individuals, showing they provide distinctive citation fingerprints, enabling nuanced comparative assessments. Since citations form networks, the Hirsch curve and five flags could more generally describe degree sequences and strengths/weights of the nodes/links of citation and other networks. [accepted in Pramana, will be available soon].

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