258 research outputs found

    Generation of domain-specific language-to-language transformation languages

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    The increasing complexity of software systems entailed by the imposed requirements and involved stakeholders creates new challenges towards software development and turns it into a complex task. Nowadays, sophisticated development approaches and tools are needed to handle this complexity. Model-Driven Engineering (MDE) provides means to abstract from the details of a software system during the development phase by using models. Domain-Specific Modeling (DSM), a branch of MDE, tackles the complexity by proposing to use modeling languages which are restricted towards the solution space of the targeted problem domain. These Domain-Specific Visual Languages (DSVLs) are used in the DSM approach to create models in the restricted design space making the generation of modeled solutions feasible and providing a basis for the communication between various stakeholders. Since for each of the targeted domains a DSVL is needed, language workbenches emerged which support the development of DSVLs. During the development of a DSVL the semantics of the language has to be defined and, if the DSVL changes, existing models created using the DSVL have to be migrated. Furthermore, models are represented in a specific format hindering the application of, e.g., mature verification methods and tools. To solve these tasks, model transformations are promoted to transform models into different representations conforming to other DSVL. This thesis presents a new kind of model transformation languages, which can be used to handle the arising tasks during the development of DSVLs. These transformation languages are tailored towards the domain of "computational model transformations between DSVLs". The presented transformation languages are based on graph-transformation approaches and simplify the specification of computations by utilizing Plotkin's Strucural Operation Semantics (SOS), and thereby facilitate the definition of computation steps in a declarative way. This approach suffers from the versatility in the scope of DSVLs and thereby requires techniques to reduce the development costs of the transformation languages for different source and target languages. The key to reduce the development costs is the application of the Domain-specific, Full-generation, Service orientation (DFS) approach for the domain of model transformation languages. The application of domain-specifc concept results in graph-based, domain-specific two-level transformation languages. The essence of those languages is captured in a pattern describing possible two-level transformation languages. This pattern is used as the basis for the definition of a generator for those kind of transformation languages making full-generation feasible. The semantics of pattern matching and rewriting rules in the context of graph-based transformations are defined by the utilization of existing graph-transformation tools

    Towards language-to-language transformation

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    This paper proposes a simplicity-oriented approach and framework for language-to-language transformation of, in particular, graphical languages. Key to simplicity is the decomposition of the transformation specification into sub-rule systems that separately specify purpose-specific aspects. We illustrate this approach by employing a variation of Plotkin’s Structural Operational Semantics (SOS) for pattern-based transformations of typed graphs in order to address the aspect ‘computation’ in a graph rewriting fashion. Key to our approach are two generalizations of Plotkin’s structural rules: the use of graph patterns as the matching concept in the rules, and the introduction of node and edge types. Types do not only allow one to easily distinguish between different kinds of dependencies, like control, data, and priority, but may also be used to define a hierarchical layering structure. The resulting Type-based Structural Operational Semantics (TSOS) supports a well-structured and intuitive specification and realization of semantically involved language-to-language transformations adequate for the generation of purpose-specific views or input formats for certain tools, like, e.g., model checkers. A comparison with the general-purpose transformation frameworks ATL and Groove, illustrates along the educational setting of our graphical WebStory language that TSOS provides quite a flexible format for the definition of a family of purpose-specific transformation languages that are easy to use and come with clear guarantees

    Method and apparatus for the synthesis of dihydroartemisinin and artemisinin derivatives

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    The present invention is directed to a method for continuous production of dihydroartemisinin and also artemisinin derivatives derived from dihydroartemisinin by using artemisinin or dihydroartemisinic acid (DHAA) as starting material as well as to a continuous flow reactor for producing dihydroartemisinin as well as the artemisinin derivatives. It was found that the reduction of artemisinin to dihydroartemisinin in a continuous process requires a special kind of reactor and a special combination of reagents comprising a hydride reducing agent, at least one activator such as an inorganic activator, at least one solid base, at least one aprotic solvent and at least one C1-C5 alcohol

    Glycoprotein biosynthesis in Saccharomyces cerevisiae: ngd29, an N-glycosylation mutant allelic to och1 having a defect in the initiation of outer chain formation

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    AbstractOuter chain glycosylation in Saccharomyces cerevisiae leads to heterogeneous and immunogenic asparagine-linked saccharide chains containing more than 50 mannose residues on secreted glycoproteins. Using a [3H]mannose suicide selection procedure a collection of N-glycosylation defective mutants (designated ngd) was isolated. One mutant, ngd29, was found to have a defect in the initiation of the outer chain and displayed a temperature growth sensitivity at 37°C allowing the isolation of the corresponding gene by complementation. Cloning, sequencing and disruption of NGD29 showed that it is a non lethal gene and identical to OCH1. It complemented both the glycosylation and growth defect. Membranes isolated from an ngd29 disruptant or an ngd29mnn1 double mutant were no longer able, in contrast to membranes from wild type cells, to transfer mannose from GDPmannose to Man8GlcNAc2, the in vivo acceptor for building up the outer chain. Heterologous expression of glucose oxidase from Aspergillus niger in an ngd29mnn1 double mutant produced a secreted uniform glycoprotein with exclusively Man8GlcNAc2 structure that in wild type yeast is heavily hyperglycosylated. The data indicate that this mutant strain is a suitable host for the expression of recombinant glycoproteins from different origin in S. cerevisiae to obtain mammalian oligomannosidic type N-linked carbohydrate chains

    Compositional Synthesis via a Convex Parameterization of Assume-Guarantee Contracts

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    We develop an assume-guarantee framework for control of large scale linear (time-varying) systems from finite-time reach and avoid or infinite-time invariance specifications. The contracts describe the admissible set of states and controls for individual subsystems. A set of contracts compose correctly if mutual assumptions and guarantees match in a way that we formalize. We propose a rich parameterization of contracts such that the set of parameters that compose correctly is convex. Moreover, we design a potential function of parameters that describes the distance of contracts from a correct composition. Thus, the verification and synthesis for the aggregate system are broken to solving small convex programs for individual subsystems, where correctness is ultimately achieved in a compositional way. Illustrative examples demonstrate the scalability of our method

    Method and device for the synthesis of Artemisinin

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    The present invention is directed to a method for producing artemisinin having the formula (6) from dihydroartennisinic acid in a continuous flow reactor using singlet oxygen as well as to the continuous flow reactor for producing artemisinin

    Continuous Synthesis of Artemisinin-Derived Medicines

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    Described is a continuous, divergent synthesis system which is coupled to continuous purification and is capable of producing four anti-malarial APIs. The system is comprised of three linked reaction modules for photooxidation/cyclization, reduction, and derivatization. A fourth module couples the crude reaction stream with continuous purification to yield pure API

    Closing two doors of viral entry: Intramolecular combination of a coreceptor- and fusion inhibitor of HIV-1

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    We describe a novel strategy in which two inhibitors of HIV viral entry were incorporated into a single molecule. This bifunctional fusion inhibitor consists of an antibody blocking the binding of HIV to its co-receptor CCR5, and a covalently linked peptide which blocks envelope mediated virus-cell fusion. This novel bifunctional molecule is highly active on CCR5- and X4-tropic viruses in a single cycle assay and a reporter cell line with IC50 values of 0.03–0.05 nM. We demonstrated that both inhibitors contribute to the antiviral activity. In the natural host peripheral blood mononuclear cells (PBMC) the inhibition of CXCR4-tropic viruses is dependant on the co-expression of CCR5 and CXCR4 receptors. This bifunctional inhibitor may offer potential for improved pharmacokinetic parameters for a fusion inhibitor in humans and the combination of two active antiviral agents in one molecule may provide better durability in controlling the emergence of resistant viruses
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