A Functional Shell that Operates on Typed and Compiled Applications

Esther is the interactive shell of Famke, a prototype implementation of a strongly typed operating system written in the functional programming language Clean. As usual, the shell can be used for manipulating files, applications, data and processes at the command line. Special about Esther is that the shell language provides the full basic functionality of a strongly typed lazy functional language. The shell type checks each command line and only executes well-typed expressions. Files are typed as well, and applications are simply files with a function type. The implementation of the shell has some unusual aspects. The type checking/inferencing performed by the shell is actually performed by the hybrid static/dynamic type system of Clean. The shell behaves like an interpreter, but it actually executes a command line by combining existing code of functions on disk. Cleans dynamic linker is used to store (and retrieve) any expression (both data and code) with its type on disk. This linker is also used to communicate values of any type, e.g., data, closures, and functions (i.e.compiled code), between running applications in a type safe way. The shell combines the advantages of interpreters (direct response) and compilers (statically typed, fast code). Applications (compiled functions) can be used, in a type safe way, in the shell, and functions defined in the shell can be used by any compiled application

Realizability criteria for compositional MSC

Synthesizing a proper implementation for a scenario-based specification is often impossible, due to the distributed nature of implementations. To be able to detect problematic specifications, realizability criteria have been identified, such as non-local choice. In this work we develop a formal framework to study realizability of compositional MSC [GMP03]. We use it to derive a complete classification of criteria that is closely related to the criteria for MSC from [MGR05]. Comparing specifications and implementations is usually complicated, because different formalisms are used. We treat both of them in terms of a single formalism. Therefore we extend the partial order semantics of [Pra86, KL98] with a way to model deadlocks and with a more sophisticated way to address communication

Human Sera Collected between 1979 and 2010 Possess Blocking-Antibody Titers to Pandemic GII.4 Noroviruses Isolated over Three Decades

The emergence of pandemic GII.4 norovirus (NoV) strains has been proposed to occur due to changes in receptor usage and thereby to lead to immune evasion. To address this hypothesis, we measured the ability of human sera collected between 1979 and 2010 to block glycan binding of four pandemic GII. 4 noroviruses isolated in the last 4 decades. In total, 268 sera were investigated for 50% blocking titer (BT50) values of virus-like particles (VLPs) against pig gastric mucin (PGM) using 4 VLPs that represent different GII. 4 norovirus variants identified between 1987 and 2012. Pre- and postpandemic sera (sera collected before and after isolation of the reference NoV strain) efficiently prevented binding of VLP strains MD145 (1987), Grimsby (1995), and Houston (2002), but not the Sydney (2012) strain, to PGM. No statistically significant difference in virus-blocking titers was observed between pre- and postpandemic sera. Moreover, paired sera showed that blocking titers of amp;gt;= 160 were maintained over a 6-year period against MD145, Grimsby, and Houston VLPs. Significantly higher serum blocking titers (geometric mean titer [GMT], 1,704) were found among IgA-deficient individuals than among healthy blood donors (GMT, 90.9) (P amp;lt; 0.0001). The observation that prepandemic sera possess robust blocking capacity for viruses identified decades later suggests a common attachment factor, at least until 2002. Our results indicate that serum IgG possesses antibody-blocking capacity and that blocking titers can be maintained for at least 6 years against 3 decades of pandemic GII. 4 NoV. IMPORTANCE Human noroviruses (NoVs) are the major cause of acute gastroenteritis worldwide. Histo-blood group antigens (HBGAs) in saliva and gut recognize NoV and are the proposed ligands that facilitate infection. Polymorphisms in HBGA genes, and in particular a nonsense mutation in FUT2 (G428A), result in resistance to global dominating GII. 4 NoV. The emergence of new pandemic GII. 4 strains occurs at intervals of several years and is proposed to be attributable to epochal evolution, including amino acid changes and immune evasion. However, it remains unclear whether exposure to a previous pandemic strain stimulates immunity to a pandemic strain identified decades later. We found that prepandemic sera possess robust virus-blocking capacity against viruses identified several decades later. We also show that serum lacking IgA antibodies is sufficient to block NoV VLP binding to HBGAs. This is essential, considering that 1 in every 600 Caucasian children is IgA deficient.Funding Agencies|Swedish Research Council [320301, 8266]; Swedish Foundation for Strategic Research</p