Programming Languages shouldn't be "too Natural"

Despite much research on programming language principles, most often the design of modern languages ignores such principles which results in cumbersome, hard to understand, and error-prone code. We substantiate our claim through a short sampling of the features of some widely used languages and by referring to other criticisms widely publicized in the literature. We argue that a major reason of such an unpleasant state of the art is that programming languages evolve in a way that too much resembles that of natural languages. We advocate a different attitude in programming language design, going back to essentiality and rigorous application of few basic, well-chosen principles

Syntax-driven program verification of matching logic properties

We describe a novel approach to program verification and its application to verification of C programs, where properties are expressed in matching logic. The general approach is syntax-directed: semantic rules, expressed according to Knuths attribute grammars, specify how verification conditions can be computed. Evaluation is performed by interplaying attribute computation and propagation through the syntax tree with invocation of a solver of logic formulae. The benefit of a general syntax-driven approach is that it provides a reusable reference scheme for implementing verifiers for different languages. We show that the instantiation of a general approach to a specific language does not penalize the efficiency of the resulting verifier. This is done by comparing our C verifier for matching logic with an existing tool for the same programming language and logic. A further key advantage of the syntax-directed approach is that it can be the starting point for an incremental verifier -- which is our long-term research target

ArchiTRIO: a UML-compatible language for architectural description and its formal semantics

ArchiTRIO [14] is a formal language, which complements UML 2.0 concepts with a formal, logic-based notation that allows users to state system-wide properties, both static and dynamic, including real- time constraints. In this paper we present the semantics of the core con- cepts of the ArchiTRIO language. As the core elements of ArchiTRIO coincide with those of UML 2.0 (operation, interface, port, class), the semantics of ArchiTRIO provides also a formal definition for the basic concepts on which UML 2.0 is built

A putative helical cytokine functioning in innate immune signalling in Drosophila melanogaster

In invertebrates and vertebrates, innate immunity is considered the first line of defense mechanism against non-self material. In vertebrates,cytokines play a critical role in innate immune signalling. To date, however, the existence of genes encoding for invertebrate helical cytokines hasbeen anticipated, but never demonstrated. Here, we report the first structural and functional evidence of a gene encoding for a putative helicalcytokine in Drosophila melanogaster. Functional experiments demonstrate that its expression, as well as that of the antimicrobial factors defensinand cecropin A1, is significantly increased after immune stimulation. These observations suggest the involvement of helical cytokines in the innateimmune response of invertebrates

A test generation framework for quiescent real-time systems

We present an extension of Tretmans theory and algorithm for test generation for input-output transition systems to real-time systems. Our treatment is based on an operational interpretation of the notion of quiescence in the context of real-time behaviour. This gives rise to a family of implementation relations parameterized by observation durations for quiescence. We define a nondeterministic (parameterized) test generation algorithm that generates test cases that are sound with respect to the corresponding implementation relation. Also, the test generation is exhaustive in the sense that for each non-conforming implementation a test case can be generated that detects the non-conformance

Study of the bacterial community affiliated to Hyalesthes obsoletus, the insect vector of “bois noir” phytoplasma of grape

Grape yellows caused by phytoplasmas afflict several important wine-producing areas of Europe. A grape yellows with increasingincidence in European vineyards is “bois noir” (BN), caused by ‘Candidatus Phytoplasma solani’. Its vector is the planthopperHyalesthes obsoletus Signoret (Hemiptera Cixiidae), occasionally feeding on grapevine. An innovative strategy for reducing thediffusion of the disease could be symbiotic control, exploiting the action of symbiotic microorganisms of the insect host. To investigatethe occurrence of possible microbial candidates for symbiotic control we performed a molecular characterization of thebacteria associated to H. obsoletus. Length heterogeneity PCR was applied for a preliminary population screening. Taxonomicaffiliations of the bacterial species were analyzed by denaturing gradient gel electrophoresis, showing, within the microbial diversity,the intracellular reproductive parasite Wolbachia pipientis and a Bacteroidetes symbiont with 92% nt identity with ‘CandidatusSulcia muelleri’. PCR essays specific for these bacteria showed they co-localize in several organs of H. obsoletus. Fluorescentin situ hybridization was performed to assess the distribution of these microorganisms within the insect body, showing interestinglocalization patterns, particularly in insect gonads and salivary glands. These results could be a starting point for a deeper investigationof functions and relationships between microbial species

Fragmentation studies of high energy ions using CR39 nuclear track detectors

We report on the measurements of the total charge changing fragmentation cross sections in high-energy nucleus-nucleus collisions using Fe, Si and Pb incident ions. Several stacks of CR39 nuclear track detectors with different target combinations were exposed at normal incidence to high energy accelerator beams to integrated densities of about 2000 ions/cm^2. The nuclear track detector foils were chemically etched, and ion tracks were measured using an automatic image analyzer system. The cross section determination is based on the charge identification of beam ions and their fragments and on the reconstruction of their path through the stacks.Comment: 5 pages, 4 EPS figures. Corrected Eq. 3 and Table 1. Presented at the 10th Inter. Symp. Radiat. Phys., Coimbra, Portugal, 17-22 Sept. 200