Designing Business Models for Platform as a Service: Towards a Design Theory

Platform as a Service (PaaS) solutions are changing the way that software is produced, distributed, consumed, and priced. Unlike Software as a Service or Infrastructure as a Service, PaaS allows for value co-creation by offering complementary components and applications that are developed in emerging ecosystems of third-party developers. Despite increasing interest among practitioners and researchers, there has been little work in understanding how PaaS business models should be designed to establish a flourishing ecosystem. We aim at developing a design theory that facilitates the design of PaaS business models, taking into account the specifics of multisided business models. Four meta-requirements describe the purpose and scope of our design theory, and six design principles guide PaaS providers in designing effective business models. By focusing on designing business models, our research goes beyond previous approaches for studying PaaS

Business Models of Platform as a Service (PaaS) Providers: Current State and Future Directions

Cloud Computing, Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a Service (IaaS) are terms that denote new developments in the software industry that are completely changing the way software is produced, consumed, and distributed. In particular new PaaS business models have a disruptive effect on existing business models and require thorough business model innovation in the software industry. Despite their impact, PaaS business models have not been considered in a sufficient manner in literature yet. The paper at hand contributes to this gap by providing an overview of typical characteristics of PaaS based on a systematic literature review, a classification model of existing PaaS business models based on case studies and an overview of the current state and future development directions of PaaS

Thermodynamic reaction control of nucleoside phosphorolysis

Nucleoside analogs represent a class of important drugs for cancer and antiviral treatments. Nucleoside phosphorylases (NPases) catalyze the phosphorolysis of nucleosides and are widely employed for the synthesis of pentose‐1‐phosphates and nucleoside analogs, which are difficult to access via conventional synthetic methods. However, for the vast majority of nucleosides, it has been observed that either no or incomplete conversion of the starting materials is achieved in NPase‐catalyzed reactions. For some substrates, it has been shown that these reactions are reversible equilibrium reactions that adhere to the law of mass action. In this contribution, we broadly demonstrate that nucleoside phosphorolysis is a thermodynamically controlled endothermic reaction that proceeds to a reaction equilibrium dictated by the substrate‐specific equilibrium constant of phosphorolysis, irrespective of the type or amount of NPase used, as shown by several examples. Furthermore, we explored the temperature‐dependency of nucleoside phosphorolysis equilibrium states and provide the apparent transformed reaction enthalpy and apparent transformed reaction entropy for 24 nucleosides, confirming that these conversions are thermodynamically controlled endothermic reactions. This data allows calculation of the Gibbs free energy and, consequently, the equilibrium constant of phosphorolysis at any given reaction temperature. Overall, our investigations revealed that pyrimidine nucleosides are generally more susceptible to phosphorolysis than purine nucleosides. The data disclosed in this work allow the accurate prediction of phosphorolysis or transglycosylation yields for a range of pyrimidine and purine nucleosides and thus serve to empower further research in the field of nucleoside biocatalysis.DFG, 390540038, EXC 2008: UniSysCatTU Berlin, Open-Access-Mittel - 201

Do End Users Accept End User Development?

Do end-users accept end-user development by using enterprise mashups? Using the technology acceptance model, this research investigates the acceptance of the FAST platform, which enables endusers to build their own application by simply drag and drop graphical building blocks onto a canvas. An evaluation workshop of 159 individuals in various countries and locations found strong support of the idea. It was revealed that perceived usefulness strongly affected the attitude towards using enterprise mashups for end-user development. In turn, perceived ease of use did not. With respect to the developed mashup platform it was found that the available content within a mashup platform is the main influencing factor on the acceptance of end-user development by using mashups

USER-ORIENTED CLOUD SERVICE DESIGN BASED ON MARKET RESEARCH TECHNIQUES

For the IT industry, cloud computing has a disruptive effect, since it fundamentally changes how IT resources are produced, distributed, consumed, and priced. Designing cloud services remains a challenge, as the markets are very dynamic and cloud users are heterogeneous, locally distributed and not within the reach of the organization. This research-in-progress paper suggests the use of market research techniques, namely conjoint analysis, in the requirements elicitation process for cloud services. The contribution is a method component that extends existing requirements engineering methods. It supports cloud service providers in addressing specific questions of cloud service design: to analyse user preferences and the many trade-offs between different functional, non-functional and economic properties, to identify customer segments and develop tailored offerings, to analyse willingness-to-pay for specific features and to simulate market reactions of new designs

Representation of fractal curves by means of L systems

This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in APL Quote Quad, http://dx.doi.org/10.1145/253417.253348Proceedings of the conference on Designing the future, APL'96; published as an articleFractals can be represented by means of L-systems (Development Grammars), together with a graphic interpretation. Two families of graphic interpretations have been used: turtle graphics and vector graphics. This paper describes an APL2/PC system able to draw fractals represented by L-systems, with both graphic interpretations. A theorem has been proved on the equivalence conditions for both interpretations. Another point shown is the fact that supposed deficiencies in L-systems that have prompted proposals of extensions are really deficiencies in the graphic translation scheme

The "Cocooned Giant": Germany and European Security

I min studie har jag följt åtta elever med svenska som andraspråk genom förskoleklassen och årskurs ett. Syftet medstudien har varit att söka förståelse för varför elever lyckas så olika med sin läs- och skrivinlärning trots att de fårsamma undervisning. Min hypotes har varit att de elever som får svårigheter med att lära sig läsa och skriva inte ärdelaktiga i skolans språkliga gemenskap. För att söka stöd för mitt antagande har jag observerat eleverna under den pedagogiska samlingen i förskoleklassen.Då observationsstudien var avslutad tog jag del av resultaten på de test som skolan genomförde under tiden iförskoleklassen och årskurs ett. Jag har också intervjuat elevernas föräldrar och läraren i förskoleklassen.Inledningsvis har jag gjort en teoretisk genomlysning av följande områden: Språklig gemenskap, socialisering tillskriftspråksanvändning, flerspråkighet och andraspråksinlärning, svenska som andraspråk,modersmålsundervisning samt förskoleklassen. Jag fann att det är nödvändigt att använda flera metoder för att upptäcka de elever som riskerar att få svårighetermed sin läs- och skrivinlärning. Under observationerna framgick det tydligt hur elever som inte är fonologisktmedvetna förhåller sig till den pedagogiska samlingen. Däremot identifierade jag inte de elever som hade ett mycketbegränsat ordförråd. Detta framgick då elevernas ordförråd testades när de började i årskurs ett. Då en förutsättningför att vara delaktig i den språkliga gemenskapen är att eleven förstår ordens betydelse bör detta test genomföras såtidigt som möjligt då eleven börjar i förskoleklassen. Jag fann också att studiehandledning på modersmålet är ettviktigt stöd för många elever om de har ett begränsat ordförråd i undervisningsspråket

Efficient Biocatalytic Synthesis of Dihalogenated Purine Nucleoside Analogues Applying Thermodynamic Calculations

The enzymatic synthesis of nucleoside analogues has been shown to be a sustainable and efficient alternative to chemical synthesis routes. In this study, dihalogenated nucleoside analogues were produced by thermostable nucleoside phosphorylases in transglycosylation reactions using uridine or thymidine as sugar donors. Prior to the enzymatic process, ideal maximum product yields were calculated after the determination of equilibrium constants through monitoring the equilibrium conversion in analytical-scale reactions. Equilibrium constants for dihalogenated nucleosides were comparable to known purine nucleosides, ranging between 0.071 and 0.081. To achieve 90% product yield in the enzymatic process, an approximately five-fold excess of sugar donor was needed. Nucleoside analogues were purified by semi-preparative HPLC, and yields of purified product were approximately 50% for all target compounds. To evaluate the impact of halogen atoms in positions 2 and 6 on the antiproliferative activity in leukemic cell lines, the cytotoxic potential of dihalogenated nucleoside analogues was studied in the leukemic cell line HL-60. Interestingly, the inhibition of HL-60 cells with dihalogenated nucleoside analogues was substantially lower than with monohalogenated cladribine, which is known to show high antiproliferative activity. Taken together, we demonstrate that thermodynamic calculations and small-scale experiments can be used to produce nucleoside analogues with high yields and purity on larger scales. The procedure can be used for the generation of new libraries of nucleoside analogues for screening experiments or to replace the chemical synthesis routes of marketed nucleoside drugs by enzymatic processes.DFG, 390540038, EXC 2008: UniSysCatDFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität Berli

A UV/Vis Spectroscopy-Based Assay for Monitoring of Transformations Between Nucleosides and Nucleobases

Efficient reaction monitoring is crucial for data acquisition in kinetic and mechanistic studies. However, for conversions of nucleosides to their corresponding nucleobases, as observed in enzymatically catalyzed nucleoside phosphorylation reactions, the current analytical arsenal does not meet modern requirements regarding cost, speed of analysis and high throughput. Herein, we present a UV/Vis spectroscopy-based assay employing an algorithm for spectral unmixing in a 96-well plate format. The algorithm relies on fitting of reference spectra of nucleosides and their bases to experimental spectra and allows determination of nucleoside/nucleobase ratios in solution with high precision. The experimental procedure includes appropriate dilution of a sample into aqueous alkaline solution, transfer to a multi-well plate, measurement of a UV/Vis spectrum and subsequent in silico spectral unmixing. This enables data collection in a high-throughput fashion and reduces costs compared to state-of-the-art HPLC analyses by approximately 5-fold while being 20-fold faster and offering comparable precision. Additionally, the method is robust regarding dilution and sample transfer errors as it only considers spectral form and not absolute intensity. It can be applied to all natural nucleosides and nucleobases and even unnatural ones as demonstrated by several examples.DFG, 390540038, EXC 2008: UniSysCa