Designing Social Stories for a University Museum: Accessibility as an Opportunity for Teaching Innovation

Intellectual access for all is a major challenge for museums, as cognitive disabilities are diverse and require varied and personalized approaches. The contribution illustrates a pilot project in which students, trainees and undergraduates of the degree courses in Management of Cultural Heritage and Educational Sciences participated in the design of two prototypes of Social Stories with the aim of making the museum accessible to people with intellectual disabilities. The case-study was proposed in the following academic years 2019/20 and 2020/21. Although the lectures were held online during the pandemic period, analysing the experience and the social stories produced made students increase their awareness of the issues related to intellectual accessibility, and acquire specific skills in writing easy-to-read museum texts. The tested teaching method will continue to be implemented in the university museum context. The experience confirmed how university museums can rethink their action by turning the implementation of new services into an extraordinary training opportunity for pre-service museum educators

Deformed Harry Dym and Hunter-Zheng Equations

We study the deformed Harry Dym and Hunter-Zheng equations with two arbitrary deformation parameters. These reduce to various other known models in appropriate limits. We show that both these systems are bi-Hamiltonian with the same Hamiltonian structures. They are integrable and belong to the same hierarchy corresponding to positive and negative flows. We present the Lax pair description for both the systems and construct the conserved charges of negative order from the Lax operator. For the deformed Harry Dym equation, we construct the non-standard Lax representation for two special classes of values of the deformation parameters. In general, we argue that a non-standard description will involve a pseudo-differential operator of infinite order.Comment: Latex file, 15 page

The Algebra of Non-Local Charges in Non-Linear Sigma Models

We obtain the exact Dirac algebra obeyed by the conserved non-local charges in bosonic non-linear sigma models. Part of the computation is specialized for a symmetry group $O(N)$. As it turns out the algebra corresponds to a cubic deformation of the Kac-Moody algebra. The non-linear terms are computed in closed form. In each Dirac bracket we only find highest order terms (as explained in the paper), defining a saturated algebra. We generalize the results for the presence of a Wess-Zumino term. The algebra is very similar to the previous one, containing now a calculable correction of order one unit lower.Comment: 27 pages + figures available via ftp, Plain TeX, IFUSP/P-106

A Nonliearly Dispersive Fifth Order Integrable Equation and its Hierarchy

In this paper, we study the properties of a nonlinearly dispersive integrable system of fifth order and its associated hierarchy. We describe a Lax representation for such a system which leads to two infinite series of conserved charges and two hierarchies of equations that share the same conserved charges. We construct two compatible Hamiltonian structures as well as their Casimir functionals. One of the structures has a single Casimir functional while the other has two. This allows us to extend the flows into negative order and clarifies the meaning of two different hierarchies of positive flows. We study the behavior of these systems under a hodograph transformation and show that they are related to the Kaup-Kupershmidt and the Sawada-Kotera equations under appropriate Miura transformations. We also discuss briefly some properties associated with the generalization of second, third and fourth order Lax operators.Comment: 11 pages, LaTex, version to be published in Journal of Nonlinear Mathematical Physics, has expanded discussio

Composite nanostructured solid-acid fuel-cell electrodes via electrospray deposition

Stable, porous, nanostructured composite electrodes were successfully fabricated via the inexpensive and scalable method of electrospray deposition, in which a dissolved solute is deposited onto a substrate using an electric field to drive droplet migration. The desirable characteristics of high porosity and high surface area were obtained under conditions that favored complete solvent evaporation from the electrospray droplets prior to contact with the substrate. Solid acid (CsH_2PO_4) feature sizes of 100 nm were obtained from electrosprayed water–methanol solutions with 10 g L^(−1) CsH_2PO_4 and 5 g L^(−1) Pt catalyst particles suspended using polyvinylpyrrolidone (PVP). Alternative additives such as Pt on carbon and carbon-nanotubes (CNTs) were also successfully incorporated by this route, and in all cases the PVP could be removed from the electrode by oxygen plasma treatment without damage to the structure. In the absence of additives (Pt, Pt/C and CNTs), the feature sizes were larger, 300 nm, and the structure morphologically unstable, with significant coarsening evident after exposure to ambient conditions for just two days. Electrochemical impedance spectroscopy under humidified hydrogen at 240 °C indicated an interfacial impedance of ~1.5 Ω cm^2 for the Pt/CsH_2PO_4 composite electrodes with a total Pt loading of 0.3 ± 0.2 mg cm^(−2). This result corresponds to a 30-fold decrease in Pt loading relative to mechanically milled electrodes with comparable activity, but further increases in activity and Pt utilization are required if solid acid fuel cells are to attain widespread commercial adoption

Hibernus: sustaining computation during intermittent supply for energy-harvesting systems

A key challenge to the future of energy-harvesting systems is the discontinuous power supply that is often generated. We propose a new approach, Hibernus, which enables computation to be sustained during intermittent supply. The approach has a low energy and time overhead which is achieved by reactively hibernating: saving system state only once, when power is about to be lost, and then sleeping until the supply recovers. We validate the approach experimentally on a processor with FRAM nonvolatile memory, allowing it to reactively hibernate using only energy stored in its decoupling capacitance. When compared to a recently proposed technique, the approach reduces processor time and energy overheads by 76-100% and 49-79% respectively

Structure and superconductivity of LiFeAs

The lithium ions in Lithium iron arsenide phases with compositions close to LiFeAs have been located using powder neutron diffraction. These phases exhibit superconductivity at temperatures at least as high as 16 K demonstrating that superconductivity in compounds with [FeAs]- anti-PbO-type anionic layers occurs in compounds with at least three different structure types and occurs for a wide range of As-Fe-As bond angles.Comment: 3 pages, 3 figures, 3 table