@article{4276, abstract = {{We analyse an InAs/GaAs-based electric field tunable single quantum dot diode with a thin tunnelling barrier between a buried n þ -back contact and a quantum dot layer. In voltage- dependent photoluminescence measurements, we observe rich signatures from spatially direct and indirect transitions from the wetting layer and from a single quantum dot. By analysing the Stark effect, we show that the indirect transitions result from a recombination between confined holes in the wetting or quantum dot layer with electrons from the edge of the Fermi sea in the back contact. Using a 17 nm tunnel barrier which provides comparably weak tunnel coupling allowed us to observe clear signatures of direct and corresponding indirect lines for a series of neutral and positively charged quantum dot states.}}, author = {{Rai, Ashish K. and Gordon, Simon and Ludwig, Arne and Wieck, Andreas D. and Zrenner, Artur and Reuter, Dirk}}, issn = {{0370-1972}}, journal = {{physica status solidi (b)}}, keywords = {{excitons, GaAs, InAs, quantum dots, spatially indirect transitions, Stark shift}}, number = {{3}}, pages = {{437--441}}, publisher = {{Wiley}}, title = {{{Spatially indirect transitions in electric field tunable quantum dot diodes}}}, doi = {{10.1002/pssb.201552591}}, volume = {{253}}, year = {{2015}}, } @article{4331, abstract = {{We report about the fabrication and analysis of high Q photonic crystal cavities with metallic Schottky-contacts. The structures are based on GaAs n-i membranes with an InGaAs quantum well in the i-region and nanostructured low ohmic metal top-gates. They are designed for photocurrent readout within the cavity and fast electric manipulations. The cavity structures are characterized by photoluminescence and photocurrent spectroscopy under resonant excitation. We find strong cavity resonances in the photocurrent spectra and surprisingly high Q-factors up to 6500. Temperature dependent photocurrent measurements in the region between 4.5K and 310K show an exponential enhancement of the photocurrent signal and an external quantum efficiency up to 0.26.}}, author = {{Quiring, W. and Al-Hmoud, M. and Rai, A. and Reuter, Dirk and Wieck, A. D. and Zrenner, Artur}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, number = {{4}}, publisher = {{AIP Publishing}}, title = {{{Photonic crystal cavities with metallic Schottky contacts}}}, doi = {{10.1063/1.4928038}}, volume = {{107}}, year = {{2015}}, } @article{6522, abstract = {{An electric field applied to a semiconductor reduces its crystal symmetry and modifies its electronic structure which is expected to result in changes of the linear and nonlinear response to optical excitation. In GaAs, we observe experimentally strong electric field effects on the optical second (SHG) and third (THG) harmonic generation. The SHG signal for the laser-light k vector parallel to the [001] crystal axis is symmetry forbidden in the electric-dipole approximation, but can be induced by an applied electric field in the vicinity of the 1s exciton energy. Surprisingly, the THG signal, which is allowed in this geometry, is considerably reduced by the electric field. We develop a theory which provides good agreement with the experimental data. In particular, it shows that the optical nonlinearities for the 1s exciton resonance are modified in an electric field by the Stark effect, which mixes the 1s and 2p exciton states of opposite parity. This mixing acts in opposite way on the SHG and THG processes, as it leads to the appearance of forbidden SHG in (001)-oriented GaAs and decreases the crystallographic THG.}}, author = {{Brunne, D. and Lafrentz, M. and Pavlov, V. V. and Pisarev, R. V. and Rodina, A. V. and Yakovlev, D. R. and Bayer, M.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{8}}, publisher = {{American Physical Society (APS)}}, title = {{{Electric field effect on optical harmonic generation at the exciton resonances in GaAs}}}, doi = {{10.1103/physrevb.92.085202}}, volume = {{92}}, year = {{2015}}, } @article{6524, abstract = {{We use a picosecond acoustics technique to modulate the laser output of electrically pumped GaAs/AlAs micropillar lasers with InGaAs quantum dots. The modulation of the emission wavelength takes place on the frequencies of the nanomechanical extensional and breathing (radial) modes of the micropillars. The amplitude of the modulation for various nanomechanical modes is different for every micropillar which is explained by a various elastic contact between the micropillar walls and polymer environment.}}, author = {{Czerniuk, T. and Tepper, J. and Akimov, A. V. and Unsleber, S. and Schneider, C. and Kamp, M. and Höfling, S. and Yakovlev, D. R. and Bayer, M.}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, number = {{4}}, publisher = {{AIP Publishing}}, title = {{{Impact of nanomechanical resonances on lasing from electrically pumped quantum dot micropillars}}}, doi = {{10.1063/1.4906611}}, volume = {{106}}, year = {{2015}}, } @inproceedings{6529, author = {{Yakovlev, D. R. and Warkentin, W. and Brunne, D. and Mund, J. and Pavlov, V. V. and Rodina, A. V. and Pisarev, R. V. and Bayer, M.}}, booktitle = {{Nonlinear Optics and Applications IX}}, editor = {{Bertolotti, Mario and Haus, Joseph W. and Zheltikov, Alexei M.}}, location = {{Prague, Czech Rep}}, publisher = {{SPIE}}, title = {{{Novel mechanisms of optical harmonic generation on excitons in semiconductors}}}, doi = {{10.1117/12.2185309}}, year = {{2015}}, } @inproceedings{15406, author = {{Schäfer, D. and Hüllermeier, Eyke}}, booktitle = {{in Proceedings of the 2015 international Workshop on Meta-Learning and Algorithm Selection co-located ECML/PKDD, Porto, Portugal}}, pages = {{110--111}}, title = {{{Preference-based meta-learning using dyad ranking: Recommending algorithms in cold-start situations}}}, year = {{2015}}, } @inproceedings{16260, author = {{Lauter, C. and Wang, Z. and Tröster, Thomas and Brandis, R. and Köchling, D.}}, location = {{Lisbon, Portugal}}, title = {{{Methodology for the Product Engineering of Lightweight Structures in Multi-Material Design}}}, year = {{2015}}, } @article{13298, author = {{Sjjklint, Mimmi and Constantiou, Ioanna D and Trier, Matthias}}, issn = {{1556-5068}}, journal = {{SSRN Electronic Journal}}, title = {{{The Complexities of Self-Tracking - An Inquiry into User Reactions and Goal Attainment}}}, doi = {{10.2139/ssrn.2611193}}, year = {{2015}}, } @article{10027, author = {{Landmann, M. and Rauls, E. and Schmidt, Wolf Gero and Neumann, M. D. and Speiser, E. and Esser, N.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, title = {{{GaNm-plane: Atomic structure, surface bands, and optical response}}}, doi = {{10.1103/physrevb.91.035302}}, year = {{2015}}, } @inproceedings{24287, abstract = {{Terahertz frequency band of 0.06 - 10 THz is especially interesting for ultra-high-speed wireless communication to achieve data rates of 100 Gbps or higher. To accommodate this demand, advanced terahertz signal processing techniques need to be investigated. Parallel Sequence Spread Spectrum (PSSS) is a physical layer (PHY) baseband technology that seems to be suited for being used for ultra-high speed wireless communication since the receiver architecture is especially simple and can be implemented almost completely in analog hardware. In this paper, a PSSS modulated signal at a chip rate of 20 Gcps with a spectral efficiency of (only) 1 bit/s/Hz is transmitted using a linearity limited 240 GHz wireless frontend. PSSS transceiver models are realized offline in MATLAB/Simulink. The PSSS transmitter generates the PSSS modulated symbols that are loaded onto an Arbitrary Waveform generator (AWG) and then transmitted using the available 240 GHz wireless frontend. A Digital Storage Oscilloscope (DSO) samples and stores the received signal. The PSSS receiver performs synchronization, channel estimation and demodulation. For a coded data rate of 20 Gbps, an eye opening of 40% and a BER of 5.4·10 -5 has been measured. These results are highly promising to achieve data rates of up to 100 Gbps with PSSS modulation using a RF-frontend having higher linear operating range and thus allowing increasing the bandwidth efficiency to 4 b/s/Hz.}}, author = {{KrishneGowda, Karthik and Messinger, Tobias and Wolf, Andreas and Kraemer, Rolf and Kallfass, Ingmar and Scheytt, Christoph}}, booktitle = {{ICUWB 2015}}, title = {{{Towards 100 Gbps Wireless Communication in THz Band with PSSS Modulation: A Promising Hardware in the Loop Experiment}}}, doi = {{10.1109/ICUWB.2015.7324520}}, year = {{2015}}, } @inproceedings{24293, abstract = {{Parallel Sequence Spread Spectrum (PSSS) is a physical layer baseband technology wherein parallel data streams are transmitted simultaneously by spreading them using orthogonal codes. PSSS was selected for the wireless sensor network standard IEEE802.15.4-2006 to increase data rate and improve performance in fading channels for frequency bands below 1 GHz. Since then it has gained interest for both wireless and wired communication links.}}, author = {{Javed, Abdul Rehman and Scheytt, Christoph}}, booktitle = {{1st URSI Atlantic Radio Science Conference (URSI AT-RASC 2015)}}, title = {{{System Design and Simulation of a PSSS Based Mixed Signal Transceiver for a 20 Gbps Bandwidth Limited Communication Link}}}, doi = {{10.1109/URSI-AT-RASC.2015.7302987}}, year = {{2015}}, } @inproceedings{30603, author = {{Paradkar, Milind and Böcker, Joachim}}, booktitle = {{2015 IEEE Energy Conversion Congress and Exposition (ECCE)}}, publisher = {{IEEE}}, title = {{{3D analytical model for estimation of eddy currentlosses in the magnets of IPM machine considering the reaction field of the induced eddy currents}}}, doi = {{10.1109/ecce.2015.7310061}}, year = {{2015}}, } @inbook{29383, author = {{Schönhärl, Korinna}}, booktitle = {{Die Krise in Griechenland. Ursprünge, Verlauf, Folgen}}, editor = {{Klemm, Ulf-Dieter and Schultheiß, Wolfgang}}, pages = {{182--197}}, publisher = {{Campus Verlag}}, title = {{{„Leider sind wir bankrott“. Zahlungsausfälle in der Geschichte Griechenlands im 19. und 20. Jahrhundert}}}, year = {{2015}}, } @inbook{29340, author = {{Göhler, T. and Schlüter, M. and Stroot, T. and Westphal, Petra}}, booktitle = {{Differenz erleben - Gesellschaft gestalten. Demokratiepädagogik in der Schule}}, editor = {{Hahn, S. and Asdonk, J. and Pauli, D. and Zenke, C.T.}}, pages = {{357--365}}, publisher = {{Wochenschau Verlag}}, title = {{{Projektorientiertes Lernen im bildungswissenschaftlichen Studienanteil der universitären Lehrer*innenausbildung. Erfahrungen in demokratiepädagogisch ausgerichteten Lernsettings}}}, year = {{2015}}, } @book{26455, editor = {{Keil, Reinhard }}, publisher = {{publishing series of the Heinz Nixdorf Institute, Paderborn}}, title = {{{20 years of learning with the World Wide Web - technology and education in dialogue}}}, volume = {{330}}, year = {{2015}}, } @inbook{33161, author = {{Süwolto, Leonie}}, booktitle = {{Limbus: Australisches Jahrbuch für germanistische Literatur- und Kulturwissenschaft, 8}}, pages = {{201--219}}, publisher = {{Altern}}, title = {{{Der Altern(d)e kann Sprechen. Sprechen aus dem Exil in Arno Geigers autobiographischer Erzählung "Der alte König in seinem Exil" (2011)}}}, year = {{2015}}, } @inbook{33923, author = {{Famula, Marta}}, booktitle = {{Medienkollisionen und Medienprothesen. Literatur – Comic – Film – Kunst – Fotografie – Musik – Theater – Internet}}, editor = {{Heidemann, Gudrun and Kaul, Susanne}}, pages = {{39–53}}, publisher = {{Lang}}, title = {{{„[D]ie Wunderbarkeiten hörten auf, das Wunder nahm zu.“ Die naturwissenschaftliche Lesbarkeit der Welt als mediale Sinnkonstitution im Werk Adalbert Stifters}}}, year = {{2015}}, } @techreport{35978, author = {{Laubenstein, Désirée and Scheer, D.}}, title = {{{Gemeinsamer Unterricht … Wie kann das gelingen?}}}, year = {{2015}}, } @article{4959, author = {{Iseke, Anja and Kocks, Birgit and Schneider, Martin and Schulze-Bentrop, Conrad}}, journal = {{R\&D Management}}, number = {{1}}, pages = {{23----40}}, title = {{{Cross-cutting organizational and demographic divides and the performance of research and development teams: two wrongs can make a right}}}, year = {{2015}}, } @inproceedings{46373, abstract = {{The need for automatic methods of topic discovery in the Internet grows exponentially with the amount of available textual information. Nowadays it becomes impossible to manually read even a small part of the information in order to reveal the underlying topics. Social media provide us with a great pool of user generated content, where topic discovery may be extremely useful for businesses, politicians, researchers, and other stakeholders. However, conventional topic discovery methods, which are widely used in large text corpora, face several challenges when they are applied in social media and particularly in Twitter – the most popular microblogging platform. To the best of our knowledge no comprehensive overview of these challenges and of the methods dedicated to address these challenges does exist in IS literature until now. Therefore, this paper provides an overview of these challenges, matching methods and their expected usefulness for social media analytics.}}, author = {{Chinnov, Andrey and Kerschke, Pascal and Meske, Christian and Stieglitz, Stefan and Trautmann, Heike}}, booktitle = {{Proceedings of the 20$^th$ Americas Conference on Information Systems (AMCIS ’15)}}, isbn = {{978-0-9966831-0-4}}, pages = {{1–10}}, title = {{{An Overview of Topic Discovery in Twitter Communication through Social Media Analytics}}}, year = {{2015}}, }