@inproceedings{366, abstract = {{On-The-Fly (OTF) Computing constitutes an approach towards highly dynamic and individualized software markets. Based on service-oriented computing, OTF Computing is about realizing global markets of services that can be flexibly combined. We report on our current research activities, the security and privacy implications thereof, and our approaches to tackle the challenges. Furthermore, we discuss how the security and privacy challenges are addressed in research projects similar to OTF Computing.}}, author = {{Petrlic, Ronald and Jungmann, Alexander and Platenius, Marie Christin and Schäfer, Wilhelm and Sorge, Christoph}}, booktitle = {{Tagungsband der 4. Konferenz Software-Technologien und -Prozesse (STeP 2014)}}, pages = {{131--142}}, title = {{{Security and Privacy Challenges in On-The-Fly Computing}}}, year = {{2014}}, } @article{3663, author = {{Rausch, Andreas and Seifried, Jürgen and Harteis, Christian}}, journal = {{Zeitschrift für Erziehungswissenschaft}}, number = {{Sonderheft}}, pages = {{127----147}}, title = {{{Ausbleibende Effekte pädagogischer Professionalisierung des betrieblichen Ausbildungspersonals: Ergebnisse einer Längsschnittstudie}}}, volume = {{17}}, year = {{2014}}, } @inbook{3664, author = {{Gijbels, David and Harteis, Christian and Donche, Vincent and Van den Bossche, Piet and Maes, Steffi and Temmen, Katrin}}, booktitle = {{Discourses on Professional Learning}}, editor = {{Harteis, Christian and Seifried, Jürgen and Rausch, Andreas}}, pages = {{177----188}}, publisher = {{Springer}}, title = {{{Grasping learning during internships: the case of engineering education}}}, year = {{2014}}, } @inbook{3665, author = {{Harteis, Christian and Rausch, Andreas and Seifried, Jürgen}}, booktitle = {{Discourses on Professional Learning}}, editor = {{Harteis, Christian and Seifried, Jürgen and Rausch, Andreas}}, pages = {{1----7}}, publisher = {{Springer}}, title = {{{Discourses on professional learning: On the boundary between learning and working}}}, year = {{2014}}, } @book{3666, editor = {{Harteis, Christian and Rausch, Andreas and Seifried, Jürgen}}, publisher = {{Springer}}, title = {{{Discourses on professional learning}}}, year = {{2014}}, } @inbook{3667, author = {{Harteis, Christian and Bauer, Johannes}}, booktitle = {{International handbook of research in professional and practice-based learning}}, editor = {{Billett, Stephen and Harteis, Christian and Gruber, Hans}}, pages = {{699----732}}, title = {{{Learning from errors at work}}}, year = {{2014}}, } @book{3668, editor = {{Billett, Stephen and Harteis, Christian and Gruber, Hans}}, publisher = {{Springer}}, title = {{{International handbook of research in professional and practice-based learning}}}, year = {{2014}}, } @inproceedings{367, abstract = {{Online social networks are attracting billions of nowadays, both on a global scale as well as in social enterprise networks. Using distributed hash tables and peer-to-peer technology allows online social networks to be operated securely and efficiently only by using the resources of the user devices, thus alleviating censorship or data misuse by a single network operator. In this paper, we address the challenges that arise in implementing reliably and conveniently to use distributed data structures, such as lists or sets, in such a distributed hash-tablebased online social network. We present a secure, distributed list data structure that manages the list entries in several buckets in the distributed hash table. The list entries are authenticated, integrity is maintained and access control for single users and also groups is integrated. The approach for secure distributed lists is also applied for prefix trees and sets, and implemented and evaluated in a peer-to-peer framework for social networks. Evaluation shows that the distributed data structure is convenient and efficient to use and that the requirements on security hold.}}, author = {{Janiuk, Jens and Mäcker, Alexander and Graffi, Kalman}}, booktitle = {{Proceedings of the International Conference on Collaboration Technologies and Systems (CTS)}}, pages = {{396--405}}, title = {{{Secure Distributed Data Structures for Peer-to-Peer-based Social Networks}}}, doi = {{10.1109/CTS.2014.6867595}}, year = {{2014}}, } @inbook{3678, author = {{Daunert, Anna Liza and Harteis, Christian}}, booktitle = {{E-Learning 2.0 Technologies and Web Applications in Higher Education}}, editor = {{Pelet, J.-E.}}, pages = {{254----272}}, publisher = {{IGI Global}}, title = {{{Pre-service teachers’ perspectives and practices in utilizing ubiquitous technologies for academic-oriented learning and knowledge management}}}, year = {{2014}}, } @inproceedings{368, abstract = {{We consider the problem of scheduling a number of jobs on $m$ identical processors sharing a continuously divisible resource. Each job j comes with a resource requirement r_j \in {0,1}. The job can be processed at full speed if granted its full resource requirement. If receiving only an x-portion of r_j, it is processed at an x-fraction of the full speed. Our goal is to find a resource assignment that minimizes the makespan (i.e., the latest completion time). Variants of such problems, relating the resource assignment of jobs to their \emph{processing speeds}, have been studied under the term discrete-continuous scheduling. Known results are either very pessimistic or heuristic in nature.In this paper, we suggest and analyze a slightly simplified model. It focuses on the assignment of shared continuous resources to the processors. The job assignment to processors and the ordering of the jobs have already been fixed. It is shown that, even for unit size jobs, finding an optimal solution is NP-hard if the number of processors is part of the input. Positive results for unit size jobs include an efficient optimal algorithm for 2 processors. Moreover, we prove that balanced schedules yield a 2-1/m-approximation for a fixed number of processors. Such schedules are computed by our GreedyBalance algorithm, for which the bound is tight.}}, author = {{Brinkmann, Andre and Kling, Peter and Meyer auf der Heide, Friedhelm and Nagel, Lars and Riechers, Sören and Suess, Tim }}, booktitle = {{Proceedings of the 26th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)}}, pages = {{128--137}}, title = {{{Scheduling Shared Continuous Resources on Many-Cores}}}, doi = {{10.1145/2612669.2612698}}, year = {{2014}}, } @inbook{3685, author = {{Goller, Michael and Harteis, Christian}}, booktitle = {{Discourses on Professional Learning}}, editor = {{Harteis, Christian and Rausch, Andreas and Seifried, Jürgen}}, pages = {{189----210}}, publisher = {{Springer}}, title = {{{Employing agency in academic settings: Doctoral students shaping their own experiences}}}, year = {{2014}}, } @inbook{3686, author = {{Harteis, Christian and Goller, Michael}}, booktitle = {{Promoting, assessing, recognizing and certifying lifelong learning}}, editor = {{Halttunen, Timo and Koivisto, Mari and Billett, Stephen}}, pages = {{37----56}}, publisher = {{Springer}}, title = {{{New skills for new jobs: Work agency as a necessary condition for successful lifelong learning}}}, year = {{2014}}, } @misc{369, abstract = {{RSA Full Domain Hash ist im Zufallsorakelmodell ein EUF-CMA sicheres Signaturverfahren (existentially unforgeable under chosen-message attacks). Der Sicherheitsbeweis wird unter anderem in der Vorlesung Einf{\"u}hrung in die Kryptographie vorgestellt. Auch bei einer genaueren Analyse verliert man bei der Reduktion einen Faktor \nicefrac{1}{q_{s}}(wobei q_{s}die Anzahl der Anfragen an das Signaturorakel darstellt), was f{\"u}r die Praxis in relativ großen Systemparametern (RSA-Modul) resultiert [1].Seit der Ver{\"o}ffentlichung von [2] wurde geglaubt, dass der Faktor \nicefrac{1}{q_{s}}optimal ist. Erst zehn Jahre sp{\"a}ter offenbarten die Autoren von [3] einen Fehler in [2] und zeigten eine bessere Reduktion allerdings unter einer etwas st{\"a}rkeren Sicherheitsannahme.Die Ergebnisse aus [3] lassen sich auf PSS-Verfahren (Probabilistic Signature Scheme), das z.B. in PKCS #1 benutzt wird, {\"u}bertragen und sind somit von großer Bedeutung f{\"u}r die Praxis. Weiterhin sind die in den Beweisen verwendete Techniken n{\"u}tzlich auch bei anderen kryptographischen Verfahren.In Rahmen dieser Arbeit sollen die entsprechenden Sicherheitsbeweise aufgearbeitet und dessen Auswirkungen f{\"u}r die Praxis analysiert werden.[1] J.S. Coron, “On the Exact Security of Full Domain Hash”, CRYPTO 2000. LNCS 1880, pp. 229-235, 2000.[2] J.S. Coron, “Optimal security proofs for PPS and other signature schemes”, EUROCRYPT 2002. LNCS 2332, pp 272-287, 2002.[3] S.A. Kakvi and E. Kiltz, “Optimal Security Proofs for Full Domain Hash, Revisited”, in EUROCRYPT 2012. LNCS 7237, pp 537-553, 2012.}}, author = {{Rath, Timo}}, publisher = {{Universität Paderborn}}, title = {{{RSA-Full Domain Hash Revisited}}}, year = {{2014}}, } @article{3699, abstract = {{When taxes on capital or wealth are levied, in most countries companies have to be assessed in terms of their market value (MV). Estimating the MV of private companies for tax purposes is a challenging task for tax authorities as MVs are not available. In this study, I empirically analyse to what extent an accounting-based tax valuation method for private companies, a simplified residual income model, succeeds in matching the MV. I refer to the mandatory Standardised Combination Model that is a special case of methods commonly used in several countries. In the absence of market prices for private companies, I use a sample of small German public companies as a proxy. I validate this approach using a sensitivity analysis that involves matching the sample of public companies with that of private companies. The results imply that the mandatory Standardised Combination Model leads to a severe unequal treatment not only between public and private companies but also among private companies across and within industries. Furthermore, I simulate the effects of variation in the key parameters and highlight their impact on the approximation quality of the Standardised Combination Method. The findings are relevant to tax reform discussions as well as to tax policy-makers and practitioners in many countries.}}, author = {{Müller, Jens}}, journal = {{European Accounting Review}}, keywords = {{Challenge of Assessing, Tax Purposes}}, number = {{1}}, pages = {{117----141}}, title = {{{The challenge of assessing the market value of private companies using a standardised combination method for tax purposes--Lessons to be learnt from past experience}}}, year = {{2014}}, } @inproceedings{370, abstract = {{Max-min fairness (MMF) is a widely known approach to a fair allocation of bandwidth to each of the users in a network. This allocation can be computed by uniformly raising the bandwidths of all users without violating capacity constraints. We consider an extension of these allocations by raising the bandwidth with arbitrary and not necessarily uniform time-depending velocities (allocation rates). These allocations are used in a game-theoretic context for routing choices, which we formalize in progressive filling games (PFGs).We present a variety of results for equilibria in PFGs. We show that these games possess pure Nash and strong equilibria. While computation in general is NP-hard, there are polynomial-time algorithms for prominent classes of Max-Min-Fair Games (MMFG), including the case when all users have the same source-destination pair. We characterize prices of anarchy and stability for pure Nash and strong equilibria in PFGs and MMFGs when players have different or the same source-destination pairs. In addition, we show that when a designer can adjust allocation rates, it is possible to design games with optimal strong equilibria. Some initial results on polynomial-time algorithms in this direction are also derived. }}, author = {{Harks, Tobias and Höfer, Martin and Schewior, Kevin and Skopalik, Alexander}}, booktitle = {{Proceedings of the 33rd Annual IEEE International Conference on Computer Communications (INFOCOM'14)}}, pages = {{352--360}}, title = {{{Routing Games with Progressive Filling}}}, doi = {{10.1109/TNET.2015.2468571}}, year = {{2014}}, } @inproceedings{371, abstract = {{In this work we present the first distributed storage system that is provably robust against crash failures issued by an adaptive adversary, i.e., for each batch of requests the adversary can decide based on the entire system state which servers will be unavailable for that batch of requests. Despite up to \gamma n^{1/\log\log n} crashed servers, with \gamma>0 constant and n denoting the number of servers, our system can correctly process any batch of lookup and write requests (with at most a polylogarithmic number of requests issued at each non-crashed server) in at most a polylogarithmic number of communication rounds, with at most polylogarithmic time and work at each server and only a logarithmic storage overhead. Our system is based on previous work by Eikel and Scheideler (SPAA 2013), who presented IRIS, a distributed information system that is provably robust against the same kind of crash failures. However, IRIS is only able to serve lookup requests. Handling both lookup and write requests has turned out to require major changes in the design of IRIS.}}, author = {{Scheideler, Christian and Setzer, Alexander and Eikel, Martina}}, booktitle = {{Proceedings of the 18th International Conference on Principles of Distributed Systems (OPODIS)}}, pages = {{107----122}}, title = {{{RoBuSt: A Crash-Failure-Resistant Distributed Storage System}}}, doi = {{10.1007/978-3-319-14472-6_8}}, year = {{2014}}, } @inbook{3718, author = {{Harteis, Christian}}, booktitle = {{Herausforderung kompetenzorientierte Hochschule}}, editor = {{Arnold, Rolf and Wolf, K}}, pages = {{189--211}}, publisher = {{Schneider}}, title = {{{Auswirkungen des Bologna-Prozesses: Eine Expertise der Hochschuldidaktik}}}, year = {{2014}}, } @inbook{3719, author = {{Harteis, Christian}}, booktitle = {{Handbook of intuition research methodology}}, editor = {{Sinclair, Martha}}, pages = {{116--129}}, publisher = {{Edward Elgar}}, title = {{{Investigating intuition under the perpective of expertise: Experiences from two experimental studies}}}, year = {{2014}}, } @inproceedings{372, abstract = {{In the near future many more compute resources will be available at different geographical locations. To minimize the response time of requests, application servers closer to the user can hence be used to shorten network round trip times. However, this advantage is neutralized if the used data centre is highly loaded as the processing time of re- quests is important as well. We model the request response time as the network round trip time plus the processing time at a data centre.We present a capacitated facility location problem formal- ization where the processing time is modelled as the sojourn time of a queueing model. We discuss the Pareto trade-off between the number of used data centres and the resulting response time. For example, using fewer data centres could cut expenses but results in high utilization, high response time, and smaller revenues.Previous work presented a non-linear cost function. We prove its convexity and exploit this property in two ways: First, we transform the convex model into a linear model while controlling the maximum approximation error. Sec- ond, we used a convex solver instead of a slower non-linear solver. Numerical results on network topologies exemplify our work.}}, author = {{Keller, Matthias and Karl, Holger}}, booktitle = {{Proceedings of the SIGCOMM workshop on Distributed cloud computing}}, pages = {{47----52}}, title = {{{Response Time-Optimized Distributed Cloud Resource Allocation}}}, doi = {{10.1145/2627566.2627570}}, year = {{2014}}, } @misc{373, author = {{Pahl, David}}, publisher = {{Universität Paderborn}}, title = {{{Reputationssysteme für zusammengesetzte Dienstleistungen}}}, year = {{2014}}, }