Non-Arrhenius ionic conductivities in glasses due to a distribution of activation energies

Previously observed non-Arrhenius behavior in fast ion conducting glasses [\textit{Phys.\ Rev.\ Lett.}\ \textbf{76}, 70 (1996)] occurs at temperatures near the glass transition temperature, $T_{g}$, and is attributed to changes in the ion mobility due to ion trapping mechanisms that diminish the conductivity and result in a decreasing conductivity with increasing temperature. It is intuitive that disorder in glass will also result in a distribution of the activation energies (DAE) for ion conduction, which should increase the conductivity with increasing temperature, yet this has not been identified in the literature. In this paper, a series of high precision ionic conductivity measurements are reported for $0.5{Na}_{2}{S}+0.5[x{GeS}_{2}+(1-x){PS}_{5/2}]$ glasses with compositions ranging from $0 \leq x \leq 1$. The impact of the cation site disorder on the activation energy is identified and explained using a DAE model. The absence of the non-Arrhenius behavior in other glasses is explained and it is predicted which glasses are expected to accentuate the DAE effect on the ionic conductivity.Comment: 2 figure

Encountering and Countering Tribal Conflict With Film and Dialogue

Martin explores the ability of group leaders to overcome resistance to reconciliation in group conflicts, whether innate or otherwise. He uses an example of a group conflict that occurred across religious lines with the pending release of a movie titled Theologians Under Hitler. Even if out-group biases make group conflicts harder to resolve, offsetting that complication might be a predisposition to attend to the views of a respected leader of the in-group

Meta-evaluation of the impacts and legacy of the London 2012 Olympic Games and Paralympic Games : Developing methods paper

This report brings together the interim findings from the Developing Meta-Evaluation Methods study, which is being undertaken in conjunction with the Meta-Evaluation of the Impacts and Legacy of the London 2012 Olympic Games and Paralympic Games. The work on methods is funded by the Economic and Social Research Council (ESRC). The aim of this paper is to review the existing evidence on conducting meta-evaluation, and provide guidance appropriate to the Meta Evaluation of the Games as well as other meta-evaluation studies

Coherence Constraints for Operads, Categories and Algebras

Coherence phenomena appear in two different situations. In the context of category theory the term `coherence constraints' refers to a set of diagrams whose commutativity implies the commutativity of a larger class of diagrams. In the context of algebra coherence constrains are a minimal set of generators for the second syzygy, that is, a set of equations which generate the full set of identities among the defining relations of an algebraic theory. A typical example of the first type is Mac Lane's coherence theorem for monoidal categories, an example of the second type is the result of Drinfel'd saying that the pentagon identity for the `associator' of a quasi-Hopf algebra implies the validity of a set of identities with higher instances of this associator. We show that both types of coherence are governed by a homological invariant of the operad for the underlying algebraic structure. We call this invariant the (space of) coherence constraints. In many cases these constraints can be explicitly described, thus giving rise to various coherence results, both classical and new.Comment: 29 pages, LaTeX209, article 12pt + leqno style. A substantially revised versio

Revising Z: part I - logic and semantics

This is the first of two related papers. We introduce a simple specification logic ZC comprising a logic and a semantics (in ZF set theory) within which the logic is sound. We then provide an interpretation for (a rational reconstruction of) the specification language Z within ZC. As a result we obtain a sound logic for Z, including a basic schema calculus