Determination of flux directions by thermodynamic network analysis: Computing informative metabolite pools

Network thermodynamics focuses on the energetic analysis of complex metabolic networks. The method connects free Gibbs energies, metabolite concentrations and flux directions by fundamental thermodynamic laws. Here, a new application of network thermodynamics is presented that identifies those metabolite pools that have to be measured in order to determine as many flux directions as possible. For a medium-scaled reaction network such informative metabolite pools are computed with an approach based on Monte Carlo sampling. It turns out that some reactions can be directed with only a few measurements whereas other reactions cannot be directed even with a complete data set. High connectivity in metabolic reaction networks in alliance with concentration ranges make it impossible to intuitively foresee such results. In particular, the impact of measurements of a special type of metabolites being involved in many reactions, so called energetic currency metabolites is investigated.     

An exploratory study of api changes and usages based on apache and eclipse ecosystems

Frameworks are widely used in modern software development to reduce development costs. They are accessed through their Application Programming Interfaces (APIs), which specify the contracts with client programs. When frameworks evolve, API backward-compatibility cannot always be guaranteed and client programs must upgrade to use the new releases. Because framework upgrades are not cost-free, observing API changes and usages together at fine-grained levels is necessary to help developers understand, assess, and forecast the cost of each framework upgrade. Whereas previous work studied API changes in frameworks and API usages in client programs separately, we analyse and classify API changes and usages together in 22 framework releases from the Apache and Eclipse ecosystems and their client programs. We find that (1) missing classes and methods happen more often in frameworks and affect client programs more often than the other API change types do, (2) missing interfaces occur rarely in frameworks but affect client programs often, (3) framework APIs are used on average in 35 % of client classes and interfaces, (4) most of such usages could be encapsulated locally and reduced in number, and (5) about 11 % of APIs usages could cause ripple effects in client programs when these APIs change. Based on these findings, we provide suggestions for developers and researchers to reduce the impact of API evolution through language mechanisms and design strategies.     

Wirtschaftsinformatik zwischen Wissenschaft und Unternehmertum

One of the major success indicators for applied research sciences is the rate of transfer from research into practice. Only if concrete and economically successful products are derived from research results, such sciences can induce an impact. However, this process of innovation mandatorily needs entrepreneurship. Within the domain of business information systems, the two German enterprises SAP AG and IDS Scheer AG demonstrate that linking research and innovation is the key to lasting success in the information technology markets. German industry has significant disadvantages on the cost of human resources. Therefore it can be only successful with products that incorporate a high degree of innovation and that are consequently highly priced. But the invention of such products needs scientific research as a source of inspiration. Germany has a highly developed infrastructure of research facilities and organizations. However, they need to be better coordinated and aligned with business needs. Vice versa, enterprises need to actively approach the scientific community in order to clearly formulate their demand. Such a strategy needs changes on all sides. To achieve a change in the domain of science, it is necessary to change the profile of leading researchers, such as full professors. They should incorporate attributes of an entrepreneur and be profiled more as a research manager that tries to anticipate future needs and to develop its unit in terms of research subjects as well as personnel and financial resources. Consequently, the process of application, selection and review of leading researchers should be more oriented on processes that are common in enterprises. E. g. external head-hunters can be involved in the searching and assessing process in order to get the best qualified person for the research vacancy. Also enterprises need to change their attitude towards scientific research. In order to foster this process, executives could be invited to advisory and supervisory boards of research organisations. Furthermore, those executives must be proactively informed about the research activities and results in order to attract their interest and to show potentials for a transfer into products. There is still a long way in the hunt for innovation leadership and all these suggestions can only be a starting point.     

Scalable,password-based and threshold authentication for smart homes

Smart homes are a special use-case of the IoT paradigm, which is becoming more and more important in our lives. Although sensors, devices and applications make our daily lives easier, they often collect our sensitive data, which may lead to security problems (e.g., hacked devices, botnets, etc.). In several cases, the appropriate security mechanisms are missing within the devices. Therefore, security measures have become a central topic in the field of IoT. The most essential requirements are secure user–device authentication and confidentiality of transferred sensitive data. Passwords are the most widely used factors in various areas, such as user authentication, key establishment, and also secret sharing. Password-based protocols that are resistant to typical threats, such as offline dictionary, man-in-the-middle and phishing attacks, generate new session keys. The major aim of these solutions is to guarantee high-level security, even if a user applies a single low-entropy human memorable password for all their accounts. We introduce a threshold and password-based, distributed, mutual authenticated key agreement with key confirmation protocol for a smart home environment. The proposed protocol is a scalable and robust scheme, which forces the adversary to corrupt \(l-1\) smart home devices, where l is the threshold, in order to perform an offline dictionary attack. The protocol is designed to achieve password-only setting, and end-to-end security if the chosen IoT devices are also authenticated besides the user. We also provide a security analysis of the protocol in AVISPA. We apply the on-the-fly model checker and the constraint-logic-based attack searcher to perform protocol verification for bounded numbers of sessions. We show that the proposed protocol provides session key secrecy and mutual authentication of the user and the device manager. Since efficiency is a crucial aspect, we implemented our protocol to measure the computation and communication costs and demonstrate that our solution is appropriate and eligible for smart homes.

     

Fragile base-class problem,problem?

The fragile base-class problem (FBCP) has been described in the literature as a consequence of “misusing” inheritance and composition in object-oriented programming when (re)using frameworks. Many research works have focused on preventing the FBCP by proposing alternative mechanisms for reuse, but, to the best of our knowledge, there is no previous research work studying the prevalence and impact of the FBCP in real-world software systems. The goal of our work is thus twofold: (1) assess, in different systems, the prevalence of micro-architectures, called FBCS, that could lead to two aspects of the FBCP, (2) investigate the relation between the detected occurrences and the quality of the systems in terms of change and fault proneness, and (3) assess whether there exist bugs in these systems that are related to the FBCP. We therefore perform a quantitative and a qualitative study. Quantitatively, we analyse multiple versions of seven different open-source systems that use 58 different frameworks, resulting in 301 configurations. We detect in these systems 112,263 FBCS occurrences and we analyse whether classes playing the role of sub-classes in FBCS occurrences are more change and–or fault prone than other classes. Results show that classes participating in the analysed FBCS are neither more likely to change nor more likely to have faults. Qualitatively, we conduct a survey to confirm/infirm that some bugs are related to the FBCP. The survey involves 41 participants that analyse a total of 104 bugs of three open-source systems. Results indicate that none of the analysed bugs is related to the FBCP. Thus, despite large, rigorous quantitative and qualitative studies, we must conclude that the two aspects of the FBCP that we analyse may not be as problematic in terms of change and fault-proneness as previously thought in the literature. We propose reasons why the FBCP may not be so prevalent in the analysed systems and in other systems in general.     

An exploratory study of the impact of antipatterns on class change- and fault-proneness

Antipatterns are poor design choices that are conjectured to make object-oriented systems harder to maintain. We investigate the impact of antipatterns on classes in object-oriented systems by studying the relation between the presence of antipatterns and the change- and fault-proneness of the classes. We detect 13 antipatterns in 54 releases of ArgoUML, Eclipse, Mylyn, and Rhino, and analyse (1) to what extent classes participating in antipatterns have higher odds to change or to be subject to fault-fixing than other classes, (2) to what extent these odds (if higher) are due to the sizes of the classes or to the presence of antipatterns, and (3) what kinds of changes affect classes participating in antipatterns. We show that, in almost all releases of the four systems, classes participating in antipatterns are more change-and fault-prone than others. We also show that size alone cannot explain the higher odds of classes with antipatterns to underwent a (fault-fixing) change than other classes. Finally, we show that structural changes affect more classes with antipatterns than others. We provide qualitative explanations of the increase of change- and fault-proneness in classes participating in antipatterns using release notes and bug reports. The obtained results justify a posteriori previous work on the specification and detection of antipatterns and could help to better focus quality assurance and testing activities.     

SURFACE INTEGRITY IN THE MACHINING OF SOFT MAGNETIC NICKEL-IRON ALLOYS

With the rapid developments taking place in the electrical and electronic industries, soft magnetic materials are finding increasing application. Degradation of machined surfaces due to the mechanisms of surface formation when machining under geometrically defined cutting conditions lead to a corresponding deterioration in the magnetic properties of soft magnetic nickel-iron alloys. Graphical simulation techniques have been applied in order to study the interactive mechanics associated with the single point machining operation. Both the outcome of this simulation as well as the conclusions of experimental investigations into the milling of the soft magnetic nickel-iron alloy MUMETALL are the subject of this paper. The influence of machining on the topographical, the mechanical/ physical and the metallurgical properties of the surface and subsurface layer for the face milling operation using tungsten carbide cutting tools is discussed.