The openCARP CDE: Concept for and implementation of a sustainable collaborativedevelopment environment for research software

This work describes the setup of an advanced technical infrastructure for collabora-tive software development in large, distributed projects based on GitLab. We presentits customization and extension, additional features and processes like code review,continuous automated testing, DevOps practices, and sustainable life-cycle manage-ment including long-term preservation and citable publishing of software releasesalong with relevant metadata. The collaborative development environment (CDE) iscurrently used for developing the open cardiac simulation software openCARP and anevaluation showcases its capability and utility for collaboration and coordination ofsizeable heterogeneous teams. As such, it could be a suitable and sustainable infras-tructure solution for a wide range of research software projects

Monitoring the thermally induced transition from sp3-hybridized into sp2-hybridized carbons

The preparation of carbons for technical applications is typically based on a treatment of a precursor, which is transformed into the carbon phase with the desired structural properties. During such treatment the material passes through several different structural stages, for example, starting from precursor molecules via an amorphous phase into crystalline-like phases. While the structure of non-graphitic and graphitic carbon has been well studied, the transformation stages from molecular to amorphous and non-graphitic carbon are still not fully understood. Disordered carbon often contains a mixture of sp3-, sp2-and sp1-hybridized bonds, whose analysis is difficult to interpret. We systematically address this issue by studying the transformation of purely sp3-hybridized carbons, that is, nanodiamond and adamantane, into sp2-hybridized non-graphitic and graphitic carbon. The precursor materials are thermally treated at different temperatures and the transformation stages are monitored. We employ Raman spectroscopy, WAXS and TEM to characterize the structural changes. We correlate the intensities and positions of the Raman bands with the lateral crystallite size La estimated by WAXS analysis. The behavior of the D and G Raman bands characteristic for sp2-type material formed by transforming the sp3-hybridized precursors into non-graphitic and graphitic carbon agrees well with that observed using sp2-structured precursors

Open Surgical versus Minimal Invasive Necrosectomy of the Pancreas-A Retrospective Multicenter Analysis of the German Pancreatitis Study Group

Background Necrotising pancreatitis, and particularly infected necrosis, are still associated with high morbidity and mortality. Since 2011, a step-up approach with lower morbidity rates compared to initial open necrosectomy has been established. However, mortality and complication rates of this complex treatment are hardly studied thereafter. Methods The German Pancreatitis Study Group performed a multicenter, retrospective study including 220 patients with necrotising pancreatitis requiring intervention, treated at 10 hospitals in Germany between January 2008 and June 2014. Data were analysed for the primary endpoints "severe complications" and "mortality" as well as secondary endpoints including "length of hospital stay", "follow up", and predisposing or prognostic factors. Results Of all patients 13.6% were treated primarily with surgery and 86.4% underwent a step-up approach. More men (71.8%) required intervention for necrotising pancreatitis. The most frequent etiology was biliary (41.4%) followed by alcohol (29.1%). Compared to open necrosectomy, the step-up approach was associated with a lower number of severe complications (primary composite endpoint including sepsis, persistent multiorgan dysfunction syndrome (MODS) and erosion bleeding: 44.7% vs. 73.3%), lower mortality (10.5% vs. 33.3%) and lower rates of diabetes mellitus type 3c (4.7% vs. 33.3%). Low hematocrit and low blood urea nitrogen at admission as well as a history of acute pancreatitis were prognostic for less complications in necrotising pancreatitis. A combination of drainage with endoscopic necrosectomy resulted in the lowest rate of severe complications. Conclusion A step-up approach starting with minimal invasive drainage techniques and endoscopic necrosectomy results in a significant reduction of morbidity and mortality in necrotising pancreatitis compared to a primarily surgical intervention

Efficient and Compatible Bidirectional Formal Language Translators based on Extended Triple Graph Grammars

In the context of model-driven engineering, models play an important role in everyday life. Models are used to abstract from certain subjects and to describe artifacts and procedures. In software engineering, a system under development is often modeled on different levels of abstraction and from multiple perspectives which results in plenty of models. Moreover, the resulting models depend on each other and the need for automatically translating between related models arises in order to reduce costs, errors, and laborious manual work and to speed-up development processes. The model-driven engineering approach proposes model transformations as a key concept of model-based development which allows to automatically refine and transform models or translate between related models. Especially, bidirectional translators are often required which are able to automatically keep related models in a consistent state. The goal of bidirectional model transformations, which allow to execute transformations defined between a source and target model in both directions, is to assist in such situations. To be able to specify (bidirectional) model transformations the need for (bidirectional) model transformation languages arises. Triple graph grammars (TGGs) are a formally founded bidirectional transformation language based on graph transformations with precisely defined semantics. A TGG specification describes correspondence relationships between two languages and consists of a set of productions that declaratively specify the simultaneous evolution of both related models. The main advantage of triple graph grammars is the possibility to automatically derive bidirectionally working forward and backward translators from a TGG specification that fulfill the fundamental properties efficiency and compatibility. The grand challenge is to build translators that are efficient on the one hand and are compatible with respect to the TGG specification on the other hand. Compatibility means that translators are correct and complete with respect to the specification, i.e., pairs of models are in a consistent state after the translation operation and valid models are able to be translated into corresponding models. Moreover, the overall expressiveness of the triple graph grammar language has to be increased in order to create usable transformation specifications. But, it has to be ensured that derived translators still fulfill the fundamental properties. In this thesis, the expressiveness of triple graph grammars is increased by supporting negative application conditions (NACs) that allow to restrict the applicability of transformation rules, which is required in certain cases. In addition, we accept the challenge of providing an efficiently working translation algorithm that still fulfills the properties correctness and completeness. We extend the expressiveness of triple graph grammars by a precisely defined class of NACs together with a new translation algorithm such that for the first time the fundamental properties of TGG-based translators are still satisfied. The resulting translators nevertheless have a polynomial runtime complexity and, therefore, can be considered efficient. Moreover, they are compatible with their triple graph grammar, which makes these translators usable in practice. In conclusion, the extended triple graph grammar formalism is applicable in real world scenarios, where model transformations are bidirectionally executed to keep related models in a consistent state

Efficient and Compatible Bidirectional Formal Language Translators based on Extended Triple Graph Grammars

In the context of model-driven engineering, models play an important role in everyday life. Models are used to abstract from certain subjects and to describe artifacts and procedures. In software engineering, a system under development is often modeled on different levels of abstraction and from multiple perspectives which results in plenty of models. Moreover, the resulting models depend on each other and the need for automatically translating between related models arises in order to reduce costs, errors, and laborious manual work and to speed-up development processes. The model-driven engineering approach proposes model transformations as a key concept of model-based development which allows to automatically refine and transform models or translate between related models. Especially, bidirectional translators are often required which are able to automatically keep related models in a consistent state. The goal of bidirectional model transformations, which allow to execute transformations defined between a source and target model in both directions, is to assist in such situations. To be able to specify (bidirectional) model transformations the need for (bidirectional) model transformation languages arises. Triple graph grammars (TGGs) are a formally founded bidirectional transformation language based on graph transformations with precisely defined semantics. A TGG specification describes correspondence relationships between two languages and consists of a set of productions that declaratively specify the simultaneous evolution of both related models. The main advantage of triple graph grammars is the possibility to automatically derive bidirectionally working forward and backward translators from a TGG specification that fulfill the fundamental properties efficiency and compatibility. The grand challenge is to build translators that are efficient on the one hand and are compatible with respect to the TGG specification on the other hand. Compatibility means that translators are correct and complete with respect to the specification, i.e., pairs of models are in a consistent state after the translation operation and valid models are able to be translated into corresponding models. Moreover, the overall expressiveness of the triple graph grammar language has to be increased in order to create usable transformation specifications. But, it has to be ensured that derived translators still fulfill the fundamental properties. In this thesis, the expressiveness of triple graph grammars is increased by supporting negative application conditions (NACs) that allow to restrict the applicability of transformation rules, which is required in certain cases. In addition, we accept the challenge of providing an efficiently working translation algorithm that still fulfills the properties correctness and completeness. We extend the expressiveness of triple graph grammars by a precisely defined class of NACs together with a new translation algorithm such that for the first time the fundamental properties of TGG-based translators are still satisfied. The resulting translators nevertheless have a polynomial runtime complexity and, therefore, can be considered efficient. Moreover, they are compatible with their triple graph grammar, which makes these translators usable in practice. In conclusion, the extended triple graph grammar formalism is applicable in real world scenarios, where model transformations are bidirectionally executed to keep related models in a consistent state

All-optical Quantum Vacuum Signals in Two-Beam Collision

The fundamental theory of quantum electrodynamics predicts the vacuum to resemble a polarizable medium. This gives rise to effective nonlinear interactions between electromagnetic fields and light-by-light scattering phenomena. We study the collision of two optical laser pulses in a pump-probe setup using beams with circular and elliptic cross section and estimate the number of discernible signal photons induced by quantum vacuum nonlinearities. In this analysis we study strategies to optimize the quantum vacuum signal discernible from the background of the driving lasers. One of the main results is that the collision of two maximally focused lasers does not lead to the best discernible signal. Instead, widening the focus typically improves the signal to background separation in the far field.Comment: 18 pages, 14 figure