Calculating Colimits Compositionally

We show how finite limits and colimits can be calculated compositionally using the algebras of spans and cospans, and give as an application a proof of the Kleene Theorem on regular languages

Towards Synthesis from Assume-Guarantee Contracts involving Infinite Theories: A Preliminary Report

In previous work, we have introduced a contract-based real- izability checking algorithm for assume-guarantee contracts involving infinite theories, such as linear integer/real arith- metic and uninterpreted functions over infinite domains. This algorithm can determine whether or not it is possible to con- struct a realization (i.e. an implementation) of an assume- guarantee contract. The algorithm is similar to k-induction model checking, but involves the use of quantifiers to deter- mine implementability. While our work on realizability is inherently useful for vir- tual integration in determining whether it is possible for sup- pliers to build software that meets a contract, it also provides the foundations to solving the more challenging problem of component synthesis. In this paper, we provide an initial synthesis algorithm for assume-guarantee contracts involv- ing infinite theories. To do so, we take advantage of our realizability checking procedure and a skolemization solver for forall-exists formulas, called AE-VAL. We show that it is possible to immediately adapt our existing algorithm towards syn- thesis by using this solver, using a demonstration example. We then discuss challenges towards creating a more robust synthesis algorithm.Comment: 6 pages, 1 figur

Towards Realizability Checking of Contracts using Theories

Virtual integration techniques focus on building architectural models of systems that can be analyzed early in the design cycle to try to lower cost, reduce risk, and improve quality of complex embedded systems. Given appropriate architectural descriptions and compositional reasoning rules, these techniques can be used to prove important safety properties about the architecture prior to system construction. Such proofs build from "leaf-level" assume/guarantee component contracts through architectural layers towards top-level safety properties. The proofs are built upon the premise that each leaf-level component contract is realizable; i.e., it is possible to construct a component such that for any input allowed by the contract assumptions, there is some output value that the component can produce that satisfies the contract guarantees. Without engineering support it is all too easy to write leaf-level components that can't be realized. Realizability checking for propositional contracts has been well-studied for many years, both for component synthesis and checking correctness of temporal logic requirements. However, checking realizability for contracts involving infinite theories is still an open problem. In this paper, we describe a new approach for checking realizability of contracts involving theories and demonstrate its usefulness on several examples.Comment: 15 pages, to appear in NASA Formal Methods (NFM) 201

Motion Descriptions in English and Greek: A Cross-Typological Developmental Study of Conversations and Narratives

Theoretical claims about typologically constrained differences in how speakers habitually describe physical motion are tested through three cross-linguistic developmental studies. Three types of data are analyzed in Greek and English, languages here characterized respectively as Verb- and Satellite-framed in the coding of motion: spontaneous conversations between adults and children aged 1;8–4;6 as well as two types of narratives elicited through pictures and a film from 4-, 7-, 10-year olds and adults. Results show, on the one hand, largely predictable cross-linguistic differences, with overall greater attention paid to manner in English than in Greek and different patterns for coding path. On the other hand, the very appearance as well as intensity of typological effects also depend upon various interacting factors: the precise ways of measuring them, the age of speakers, type, content and communicative exigencies of the discourse as well as the detailed structural characteristics of a language

Rapid and mask-less laser-processing technique for the fabrication of microstructures in polydimethylsiloxane

We report a rapid laser-based method for structuring polydimethylsiloxane (PDMS) on the micron-scale. This mask-less method uses a digital multi-mirror device as a spatial light modulator to produce a given spatial intensity pattern to create arbitrarily shaped structures via either ablation or multi-photon photo-polymerisation in a master substrate, which is subsequently used to cast the complementary patterns in PDMS. This patterned PDMS mould was then used for micro-contact printing of ink and biological molecules

Laser-direct-write methods for fabrication of paper-based medical diagnostic sensors

We demonstrate the use of laser-based direct-write methods, namely laser-induced forward transfer and laser-induced photo-polymerization as printing and patterning tools for the fabrication of paper-based fluidic sensors that enable affordable point-of-care medical diagnostics

Occurrence of target-site resistance to neonicotinoids in the aphid Myzus persicae in Tunisia, and its status on different host plants

This is the peer reviewed version of the following article: Kamel Charaabi, Sonia Boukhris-bouhachem, Mohamed Makni, and Ian Denholm, ‘Occurrence of target‐site resistance to neonicotinoids in the aphid Myzus persicae in Tunisia, and its status on different host plants’, Pest Management Science, Vol. 74(6): 1297-1301, June 2018, which has been published in final form athttps://doi.org/10.1002/ps.4833 Under embargo until 19 December 2018. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.BACKGROUND: The R81T mutation conferring target-site resistance to neonicotinoid insecticides in Myzus persicae was first detected in France and has since spread across much of southern Europe. In response to recent claims of control failure with neonicotinoids in Tunisia, we have used a molecular assay to investigate the presence and distribution of this target-site mutation in samples collected from six locations and six crops attacked by M. persicae. RESULTS: The resistance allele containing R81T was present at substantial frequencies (32–55%) in aphids collected between 2014 and 2016 from northern Tunisia but was much rarer further south. It occurred in aphids collected from the aphid's primary host (peach) and four secondary crop hosts (potato, pepper, tomato and melon). Its absence in aphids from tobacco highlights complexities in the systematics of M. persicae that require further investigation. CONCLUSION: This first report of R81T from North Africa reflects a continuing expansion of its range around the Mediterranean Basin, although it remains unrecorded elsewhere in the world. Loss of efficacy of neonicotinoids presents a serious threat to the sustainability of aphid control.Peer reviewe