TY - GEN A1 - Repke, Tim A1 - Krestel, Ralf A1 - Edding, Jakob A1 - Hartmann, Moritz A1 - Hering, Jonas A1 - Kipping, Dennis A1 - Schmidt, Hendrik A1 - Scordialo, Nico A1 - Zenner, Alexander T1 - Beacon in the Dark BT - a system for interactive exploration of large email Corpora T2 - Proceedings of the 27th ACM International Conference on Information and Knowledge Management N2 - The large amount of heterogeneous data in these email corpora renders experts' investigations by hand infeasible. Auditors or journalists, e.g., who are looking for irregular or inappropriate content or suspicious patterns, are in desperate need for computer-aided exploration tools to support their investigations. We present our Beacon system for the exploration of such corpora at different levels of detail. A distributed processing pipeline combines text mining methods and social network analysis to augment the already semi-structured nature of emails. The user interface ties into the resulting cleaned and enriched dataset. For the interface design we identify three objectives expert users have: gain an initial overview of the data to identify leads to investigate, understand the context of the information at hand, and have meaningful filters to iteratively focus onto a subset of emails. To this end we make use of interactive visualisations based on rearranged and aggregated extracted information to reveal salient patterns. Y1 - 2018 SN - 978-1-4503-6014-2 U6 - https://doi.org/10.1145/3269206.3269231 SP - 1871 EP - 1874 PB - Association for Computing Machinery CY - New York ER - TY - JOUR A1 - Yang, Jie A1 - Gühr, Markus A1 - Vecchione, Theodore A1 - Robinson, Matthew Scott A1 - Li, Renkai A1 - Hartmann, Nick A1 - Shen, Xiaozhe A1 - Coffee, Ryan A1 - Corbett, Jeff A1 - Fry, Alan A1 - Gaffney, Kelly A1 - Gorkhover, Tais A1 - Hast, Carsten A1 - Jobe, Keith A1 - Makasyuk, Igor A1 - Reid, Alexander A1 - Robinson, Joseph A1 - Vetter, Sharon A1 - Wang, Fenglin A1 - Weathersby, Stephen A1 - Yoneda, Charles A1 - Centurion, Martin A1 - Wang, Xijie T1 - Diffractive imaging of a rotational wavepacket in nitrogen molecules with femtosecond megaelectronvolt electron pulses JF - Nature Communications N2 - Imaging changes in molecular geometries on their natural femtosecond timescale with sub-Angstrom spatial precision is one of the critical challenges in the chemical sciences, as the nuclear geometry changes determine the molecular reactivity. For photoexcited molecules, the nuclear dynamics determine the photoenergy conversion path and efficiency. Here we report a gas-phase electron diffraction experiment using megaelectronvolt (MeV) electrons, where we captured the rotational wavepacket dynamics of nonadiabatically laser-aligned nitrogen molecules. We achieved a combination of 100 fs root-mean-squared temporal resolution and sub-Angstrom (0.76 angstrom) spatial resolution that makes it possible to resolve the position of the nuclei within the molecule. In addition, the diffraction patterns reveal the angular distribution of the molecules, which changes from prolate (aligned) to oblate (anti-aligned) in 300 fs. Our results demonstrate a significant and promising step towards making atomically resolved movies of molecular reactions. Y1 - 2016 U6 - https://doi.org/10.1038/ncomms11232 SN - 2041-1723 VL - 7 PB - Nature Publ. Group CY - London ER - TY - GEN A1 - Yang, Jie A1 - Guehr, Markus A1 - Vecchione, Theodore A1 - Robinson, Matthew Scott A1 - Li, Renkai A1 - Hartmann, Nick A1 - Shen, Xiaozhe A1 - Coffee, Ryan A1 - Corbett, Jeff A1 - Fry, Alan A1 - Gaffney, Kelly A1 - Gorkhover, Tais A1 - Hast, Carsten A1 - Jobe, Keith A1 - Makasyuk, Igor A1 - Reid, Alexander A1 - Robinson, Joseph A1 - Vetter, Sharon A1 - Wang, Fenglin A1 - Weathersby, Stephen A1 - Yoneda, Charles A1 - Wang, Xijie A1 - Centurion, Martin T1 - Femtosecond gas phase electron diffraction with MeV electrons N2 - We present results on ultrafast gas electron diffraction (UGED) experiments with femtosecond resolution using the MeV electron gun at SLAC National Accelerator Laboratory. UGED is a promising method to investigate molecular dynamics in the gas phase because electron pulses can probe the structure with a high spatial resolution. Until recently, however, it was not possible for UGED to reach the relevant timescale for the motion of the nuclei during a molecular reaction. Using MeV electron pulses has allowed us to overcome the main challenges in reaching femtosecond resolution, namely delivering short electron pulses on a gas target, overcoming the effect of velocity mismatch between pump laser pulses and the probe electron pulses, and maintaining a low timing jitter. At electron kinetic energies above 3 MeV, the velocity mismatch between laser and electron pulses becomes negligible. The relativistic electrons are also less susceptible to temporal broadening due to the Coulomb force. One of the challenges of diffraction with relativistic electrons is that the small de Broglie wavelength results in very small diffraction angles. In this paper we describe the new setup and its characterization, including capturing static diffraction patterns of molecules in the gas phase, finding time-zero with sub-picosecond accuracy and first time-resolved diffraction experiments. The new device can achieve a temporal resolution of 100 fs root-mean-square, and sub-angstrom spatial resolution. The collimation of the beam is sufficient to measure the diffraction pattern, and the transverse coherence is on the order of 2 nm. Currently, the temporal resolution is limited both by the pulse duration of the electron pulse on target and by the timing jitter, while the spatial resolution is limited by the average electron beam current and the signal-to-noise ratio of the detection system. We also discuss plans for improving both the temporal resolution and the spatial resolution. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 326 Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-394989 ER - TY - JOUR A1 - Yang, Jie A1 - Gühr, Markus A1 - Vecchione, Theodore A1 - Robinson, Matthew Scott A1 - Li, Renkai A1 - Hartmann, Nick A1 - Shen, Xiaozhe A1 - Coffee, Ryan A1 - Corbett, Jeff A1 - Fry, Alan A1 - Gaffney, Kelly A1 - Gorkhover, Tais A1 - Hast, Carsten A1 - Jobe, Keith A1 - Makasyuk, Igor A1 - Reid, Alexander A1 - Robinson, Joseph A1 - Vetter, Sharon A1 - Wang, Fenglin A1 - Weathersby, Stephen A1 - Yoneda, Charles A1 - Wang, Xijie A1 - Centurion, Martin T1 - Femtosecond gas phase electron diffraction with MeV electrons JF - Faraday discussions N2 - We present results on ultrafast gas electron diffraction (UGED) experiments with femtosecond resolution using the MeV electron gun at SLAC National Accelerator Laboratory. UGED is a promising method to investigate molecular dynamics in the gas phase because electron pulses can probe the structure with a high spatial resolution. Until recently, however, it was not possible for UGED to reach the relevant timescale for the motion of the nuclei during a molecular reaction. Using MeV electron pulses has allowed us to overcome the main challenges in reaching femtosecond resolution, namely delivering short electron pulses on a gas target, overcoming the effect of velocity mismatch between pump laser pulses and the probe electron pulses, and maintaining a low timing jitter. At electron kinetic energies above 3 MeV, the velocity mismatch between laser and electron pulses becomes negligible. The relativistic electrons are also less susceptible to temporal broadening due to the Coulomb force. One of the challenges of diffraction with relativistic electrons is that the small de Broglie wavelength results in very small diffraction angles. In this paper we describe the new setup and its characterization, including capturing static diffraction patterns of molecules in the gas phase, finding time-zero with sub-picosecond accuracy and first time-resolved diffraction experiments. The new device can achieve a temporal resolution of 100 fs root-mean-square, and sub-angstrom spatial resolution. The collimation of the beam is sufficient to measure the diffraction pattern, and the transverse coherence is on the order of 2 nm. Currently, the temporal resolution is limited both by the pulse duration of the electron pulse on target and by the timing jitter, while the spatial resolution is limited by the average electron beam current and the signal-to-noise ratio of the detection system. We also discuss plans for improving both the temporal resolution and the spatial resolution. Y1 - 2016 U6 - https://doi.org/10.1039/c6fd00071a SN - 1359-6640 SN - 1364-5498 VL - 194 SP - 563 EP - 581 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Hill, Natascha A1 - Leow, Alexander A1 - Bleidorn, Christoph A1 - Groth, Detlef A1 - Tiedemann, Ralph A1 - Selbig, Joachim A1 - Hartmann, Stefanie T1 - Analysis of phylogenetic signal in protostomial intron patterns using Mutual Information JF - Theory in biosciences N2 - Many deep evolutionary divergences still remain unresolved, such as those among major taxa of the Lophotrochozoa. As alternative phylogenetic markers, the intron-exon structure of eukaryotic genomes and the patterns of absence and presence of spliceosomal introns appear to be promising. However, given the potential homoplasy of intron presence, the phylogenetic analysis of this data using standard evolutionary approaches has remained a challenge. Here, we used Mutual Information (MI) to estimate the phylogeny of Protostomia using gene structure data, and we compared these results with those obtained with Dollo Parsimony. Using full genome sequences from nine Metazoa, we identified 447 groups of orthologous sequences with 21,732 introns in 4,870 unique intron positions. We determined the shared absence and presence of introns in the corresponding sequence alignments and have made this data available in "IntronBase", a web-accessible and downloadable SQLite database. Our results obtained using Dollo Parsimony are obviously misled through systematic errors that arise from multiple intron loss events, but extensive filtering of data improved the quality of the estimated phylogenies. Mutual Information, in contrast, performs better with larger datasets, but at the same time it requires a complete data set, which is difficult to obtain for orthologs from a large number of taxa. Nevertheless, Mutual Information-based distances proved to be useful in analyzing this kind of data, also because the estimation of MI-based distances is independent of evolutionary models and therefore no pre-definitions of ancestral and derived character states are necessary. KW - Mutual Information KW - Evolution KW - Gene structure Y1 - 2013 U6 - https://doi.org/10.1007/s12064-012-0173-0 SN - 1431-7613 VL - 132 IS - 2 SP - 93 EP - 104 PB - Springer CY - New York ER - TY - THES A1 - Hartmann, Alexander T1 - Unterlassungsansprüche im Internet : Störerhaftung für nutzgenerierte Inhalte T2 - Information und Recht Y1 - 2009 SN - 978-3-406-59658-2 VL - 75 PB - Beck CY - München ER - TY - BOOK A1 - Fuhrmann, Michaela A1 - Goertz, Stefanie A1 - Klages, Benjamin A1 - Last, Dominique A1 - Strickroth, Sven A1 - Schubarth, Wilfried A1 - Mauermeister, Sylvi A1 - Schulze-Reichelt, Friederike A1 - Erdmann, Melinda A1 - Dreyer, Martin A1 - Konarski, Michael A1 - Tägener, Judith A1 - Lucke, Ulrike A1 - Hafer, Jörg A1 - Hartmann, Niklas A1 - Nguyen, Thi To-Uyen A1 - Wittkowski, Ariane A1 - Prickett, David James A1 - Degen, Andreas A1 - Rost, Sophia A1 - Kiy, Alexander A1 - Wagner, Nelli A1 - Gödel, Corinna A1 - Klinnert, Anne A1 - Babbe, Caroline A1 - Schneider, Marie A1 - Hille, Kerstin ED - Goertz, Stefanie ED - Klages, Benjamin ED - Last, Dominique ED - Strickroth, Sven T1 - Lehre und Lernen entwickeln - Eine Frage der Gestaltung von Übergängen BT - Erfahrungen aus 9 Jahren Qualitätspakt Lehre an der Universität Potsdam T3 - Potsdamer Beiträge zur Hochschulforschung N2 - An der Universität Potsdam wurden im Rahmen des Qualitätspakt Lehre-Projekts „Qualität etablieren in Lehre und Lernen (QueLL)“ Maßnahmen für eine Verbesserung der Studienbedingungen und eine Weiterentwicklung der Lehre und des Lernens durchgeführt. Die während der neunjährigen Projektlaufzeit thematisierten Fragestellungen, erarbeiteten Lösungsansätze und entsprechenden Erfahrungen werden im vorliegenden Sammelband in Form von wissenschaftlichen Auseinandersetzungen und Werkstattberichten dargestellt und diskutiert. Die Beiträge spiegeln in ihrer thematischen Vielfalt unterschiedliche universitäre Übergangsphasen wider, wie in diesem Fall den Übergang in die Hochschule, Übergänge innerhalb der Hochschule (im Kontext der Organisationsentwicklung, der Weiterbildung akademischer Statusgruppen oder der Entwicklung einer digitalen Lehr-Lernkultur) und schließlich den Übergang in die Berufspraxis. Denn während der Projektlaufzeit hat sich gezeigt, dass die Gestaltung von Lehre und Lernen letztlich immer eine Gestaltung solcher Übergänge ist: sowohl zwischen den innerinstitutionellen Ebenen und Bereichen als auch zwischen Akteur/innen der Hochschule und schließlich ebenso innerhalb des Student Life Cycle. Weiterhin wird anhand der Beiträge deutlich, dass die Entwicklung von Lehre und Studium nicht als isolierte Aufgabe verstanden werden kann, sondern in die Strukturen und Prozesse der Universität hineinwirken und Formen der Zusammenarbeit etablieren sollte, die es braucht, um Projekte nachhaltig zu gestalten. Ziel dieses Bandes ist es, zur Diskussion über Gelingensbedingungen einer nachhaltigen Entwicklung von Lehre und Lernen beizutragen. Damit richtet er sich an Akteur/innen aus der Hochschulleitung, an Lehrende und Forschende sowie Mitarbeitende des Third Space. T3 - Potsdamer Beiträge zur Hochschulforschung - 6 KW - Hochschulentwicklung KW - Qualität in Lehre und Studium KW - Praxisbeispiele KW - Digitalisierung KW - Student-Life-Cycle Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-476815 SN - 978-3-86956-498-2 SN - 2192-1075 SN - 2192-1083 IS - 6 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Di Bello, Costantino A1 - Hartmann, Alexander K. A1 - Majumdar, Satya N. A1 - Mori, Francesco A1 - Rosso, Alberto A1 - Schehr, Gregory T1 - Current fluctuations in stochastically resetting particle systems JF - Physical review : E, Statistical, nonlinear and soft matter physics N2 - We consider a system of noninteracting particles on a line with initial positions distributed uniformly with density ? on the negative half-line. We consider two different models: (i) Each particle performs independent Brownian motion with stochastic resetting to its initial position with rate r and (ii) each particle performs run -and-tumble motion, and with rate r its position gets reset to its initial value and simultaneously its velocity gets randomized. We study the effects of resetting on the distribution P(Q, t) of the integrated particle current Q up to time t through the origin (from left to right). We study both the annealed and the quenched current distributions and in both cases, we find that resetting induces a stationary limiting distribution of the current at long times. However, we show that the approach to the stationary state of the current distribution in the annealed and the quenched cases are drastically different for both models. In the annealed case, the whole distribution P-an(Q, t) approaches its stationary limit uniformly for all Q. In contrast, the quenched distribution P-qu(Q, t) attains its stationary form for Q < Q(crit)(t), while it remains time dependent for Q > Q(crit)(t). We show that Q(crit)(t) increases linearly with t for large t. On the scale where Q <; Q(crit)(t), we show that P-qu(Q, t) has an unusual large deviation form with a rate function that has a third-order phase transition at the critical point. We have computed the associated rate functions analytically for both models. Using an importance sampling method that allows to probe probabilities as tiny as 10-14000, we were able to compute numerically this nonanalytic rate function for the resetting Brownian dynamics and found excellent agreement with our analytical prediction. Y1 - 2023 U6 - https://doi.org/10.1103/PhysRevE.108.014112 SN - 2470-0045 SN - 2470-0053 VL - 108 IS - 1 PB - American Physical Society CY - College Park ER -