A Typed Calculus for Querying Distributed XML Documents

We study the problems related to querying large, distributed XML documents. Our proposal takes the form of a new process calculus in which XML data are processes that can be queried by means of concurrent pattern-matching expressions. What we achieve is a functional, strongly-typed programming model based on three main ingredients: an asynchronous process calculus in the style of Milner's pi-calculus and existing semantics for concurrent-ML; a model where documents and expressions are both represented as processes, and where evaluation is represented as a parallel composition of the two; a static type system based on regular expression types

Transient Cerebral Ischemic Attack and Delirium Heralding the Vasculitic Phase of Eosinophilic Granulomatosis With Polyangiitis (Churg-Strauss Syndrome)

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Sudden Unexpected Deaths and Vaccinations during the First Two Years of Life in Italy: A Case Series Study

Background The signal of an association between vaccination in the second year of life with a hexavalent vaccine and sudden unexpected deaths (SUD) in the two days following vaccination was reported in Germany in 2003. A study to establish whether the immunisation with hexavalent vaccines increased the short term risk of SUD in infants was conducted in Italy. Methodology/Principal Findings The reference population comprises around 3 million infants vaccinated in Italy in the study period 1999–2004 (1.5 million received hexavalent vaccines). Events of SUD in infants aged 1–23 months were identified through the death certificates. Vaccination history was retrieved from immunisation registries. Association between immunisation and death was assessed adopting a case series design focusing on the risk periods 0–1, 0–7, and 0–14 days after immunisation. Among the 604 infants who died of SUD, 244 (40%) had received at least one vaccination. Four deaths occurred within two days from vaccination with the hexavalent vaccines (RR = 1.5; 95% CI 0.6 to 4.2). The RRs for the risk periods 0–7 and 0–14 were 2.0 (95% CI 1.2 to 3.5) and 1.5 (95% CI 0.9 to 2.4). The increased risk was limited to the first dose (RR = 2.2; 95% CI 1.1 to 4.4), whereas no increase was observed for the second and third doses combined. Conclusions The RRs of SUD for any vaccines and any risk periods, even when greater than 1, were almost an order of magnitude lower than the estimates in Germany. The limited increase in RRs found in Italy appears confined to the first dose and may be partly explained by a residual uncontrolled confounding effect of age

M.: Responsiveness in process calculi

A system guarantees responsive usage of a channel r if a communication along r is guaranteed to eventually take place. Responsiveness is important, for instance, to ensure that any request to a service be eventually replied. We propose two distinct type systems, each of which statically guarantees responsive usage of names in well-typed pi-calculus processes. In the first system, we achieve responsiveness by combining techniques for deadlock and livelock avoidance with linearity and receptiveness. The latter is a guarantee that a name is ready to receive as soon as it is created. These conditions imply relevant limitations on the nesting of actions and on multiple use of names in processes. In the second system, we relax these requirements so as to permit certain forms of nested inputs and multiple outputs. We demonstrate the expressive power of the two systems by showing that primitive recursive functions – in the case of the first system – and Cook and Misra’s service orchestration language ORC – in the case of the second system – can be encoded into well-typed processes

Deciding safety properties in infinite-state pi-calculus via behavioural types. Extended version. http://gdn.dsi.unifi.it/~acciai/papers/icalpFull.pdf

Abstract. In the pi-calculus, we consider decidability of certain safety properties expressed in a simple spatial logic. We first introduce a behavioural type system that, for any process P, extracts a spatial-behavioural type T in the form of a ccs term that is logically equivalent to the given process. Using techniques based on well-structured transition systems, we prove that, for an interesting fragment of the logic, satisfiability T | = φ is decidable for types. As a consequence of logical equivalence between types and processes, we obtain decidability of this fragment of the logic for all well-typed pi-processes

Behavioural contracts with request\u2013response operations

In the context of service-oriented computing, behavioural contracts are abstract descriptions of the message-passing behaviour of services. They can be used to check properties of service compositions such as, for instance, client-service compliance. To the best of our knowledge, previous formal models for contracts consider unidirectional send and receive operations. In this paper, we present two models for contracts with bidirectional request\u2013response operations, in the presence of unboundedly many instances of both clients and servers. The first model takes inspiration from the abstract service interface language WSCL, the second one is inspired by Abstract WS-BPEL. We prove that two different notions of client-service compliance (one based on client satisfaction and another one requiring mutual completion) are decidable in the former while they are undecidable in the latter, thus showing an interesting expressiveness gap between the modelling of request\u2013response operations in WSCL and in Abstract WS-BPEL