A Rewrite Framework for Language Definitions and for Generation of Efficient Interpreters

A rewrite logic semantic definitional framework for programming languages is introduced, called K, together with partially automated translations of K language definitions into rewriting logic and into C. The framework is exemplified by defining SILF, a simple imperative language with functions. The translation of K definitions into rewriting logic enables the use of the various analysis tools developed for rewrite logic specifications, while the translation into C allows for very efficient interpreters. A suite of tests show the performance of interpreters compiled from K definitions

Streamlining Policy Creation in Policy Frameworks

{\it Policy frameworks} provide a technique for improving reuse in program analysis: the same language frontend, and a core analysis semantics, can be shared among multiple analysis policies for the same language, while analysis domains (such as units of measurement) can be shared among frameworks for different languages. One limitation of policy frameworks is that, in practice, adding a new policy can still require a significant level of knowledge about the internals of the semantics definition. This abstract describes work on extending policy frameworks to solve this limitation, making policies reflective over their requirements and generating the policy semantics from a higher-level policy description language

Visfatin reduces gap junction mediated cell-to-cell communication in proximal tubule-derived epithelial cells

Background/Aims: In the current study we examined if the adipocytokine, visfatin, alters connexin-mediated intercellular communication in proximal tubule-derived epithelial cells. Methods: The effects of visfatin (10-200ng/mL) on cell viability and cytotoxicity in HK2-cells were assessed by MTT, crystal violet and lactate dehydrogenase assays. Western blot analysis was used to confirm expression of Cx26, Cx40 and Cx43. The effect of visfatin (10-200ng/mL) on TGF-β1 secretion was confirmed by ELISA, and the effects of both TGF-β1 (2-10ng/mL) and visfatin (10-200ng/mL) on connexin expression were assessed by western blot. Functional intercellular communication was determined using transfer of Lucifer Yellow and paired-whole cell patch clamp electrophysiology. Results: In low glucose (5mM), visfatin (10-200ng/mL) did not affect membrane integrity, cytotoxicity or cell viability at 48hrs, but did evoke a concentration-dependent reduction in Cx26 and Cx43 expression. The expression of Cx40 was unaffected. At 48hrs, visfatin (10-200ng/mL) increased the secretion of TGF-β1 and the visfatin-evoked changes in connexin expression were mimicked by exogenous application of the pro-fibrotic cytokine (2-10ng/ml). Visfatin reduced dye transfer between coupled cells and decreased functional conductance, with levels falling by 63% as compared to control. Although input resistance was increased following visfatin treatment by 166%, the change was not significant as compared to control. The effects of visfatin on Cx-expression and cell-coupling were blocked in the presence of a TGF-β1 specific neutralizing antibody. Conclusions: The adipocytokine visfatin selectively evoked a non-toxic reduction in connexin expression in HK2-cells. The loss in gap-junction associated proteins was mirrored by a loss in functional conductance between coupled cells. Visfatin increased TGF-β secretion and the pattern of change for connexins expression was mimicked by exogenous application of TGF-β1. The effect of visfatin on Cx-expression and dye transfer were negated in the presence of a TGF-β1 neutralising antibody. These data suggest that visfatin reduces connexin-mediated intercellular communication in proximal tubule-derived epithelial cells via a TGF-β dependent pathway. © 2013 S. Karger AG, Base

Arctic Profiles: Second Series

In the June 1982 issue of Arctic, Richard Davis introduced "Arctic Profiles." At the time he said the purpose of the series was to cover "a more subjective and human element that has influenced the history of arctic development." He continued, "Should this series prove successful ..." more could follow. ... Because of the success of the Profiles, Arctic has decided to maintain the series and has asked us to see it through a second phase. ... The second series of profiles will be more contemporary but continue to recognize the contribution of those no longer active or alive. ..

A Rewriting Logic Semantics Approach to Modular Program Analysis

The K framework, based on rewriting logic semantics, provides a powerful logic for defining the semantics of programming languages. While most work in this area has focused on defining an evaluation semantics for a language, it is also possible to define an abstract semantics that can be used for program analysis. Using the SILF language (Hills, Serbanuta and Rosu, 2007), this paper describes one technique for defining such a semantics: policy frameworks. In policy frameworks, an analysis-generic, modular framework is first defined for a language. Individual analyses, called policies, are then defined as extensions of this framework, with each policy defining analysis-specific semantic rules and an annotation language which, in combination with support in the language front-end, allows users to annotate program types and functions with information used during program analysis. Standard term rewriting techniques are used to analyze programs by evaluating them in the policy semantics

Static, Lightweight Includes Resolution for PHP

Dynamic languages include a number of features that are challenging to model properly in static analysis tools. In PHP, one of these features is the include expression, where an arbitrary expression provides the path of the file to include at runtime. In this paper we present two complementary analyses for statically resolving PHP includes, one that works at the level of individual PHP files and one targeting PHP programs, possibly consisting of multiple scripts. To evaluate the effectiveness of these analyses we have applied the first to a corpus of 20 open-source systems, totaling more than 4.5 million lines of PHP, and the second to a number of programs from a subset of these systems. Our results show that, in many cases, includes can be either resolved to a specific file or a small subset of possible files, enabling better IDE features and more advanced program analysis tools for PHP

Meta-Language Support for Type-Safe Access to External Resources

Meta-programming applications often require access to heterogeneous sources of information, often from different technological spaces (grammars, models, ontologies, databases), that have specialized ways of defining their respective data schemas. Without direct language support, obtaining typed access to this external, potentially changing, information is a tedious and error-prone engineering task. The Rascal meta-programming language aims to support the import and manipulation of all of these kinds of data in a type-safe manner. The goal is to lower the engineering effort to build new meta programs that combine information about software in unforeseen ways. In this paper we describe built-in language support, so called \textit{resources}, for incorporating external sources of data and their corresponding data-types while maintaining type safety. We demonstrate the applicability of Rascal resources by example, sho

Program Analysis Scenarios in Rascal

Rascal is a meta programming language focused on the implementation of domain-specific languages and on the rapid construction of tools for software analysis and software transformation. In this paper we focus on the use of Rascal for software analysis. We illustrate a range of scenarios for building new software analysis tools through a number of examples, including one showing integration with an existing Maude-based analysis. We then focus on ongoing work on alias analysis and type inference for PHP, showing how Rascal is being used, and sketching a hypothetical solution in Maude. We conclude with a high-level discussion on the commonalities and differences between Rascal and Maude when applied to program analysis