TY - THES A1 - Schröter, Martin T1 - Newton Methods for Image Registration T1 - Newton-Methoden zur Bildregistrierung N2 - Consider the situation where two or more images are taken from the same object. After taking the first image, the object is moved or rotated so that the second recording depicts it in a different manner. Additionally, take heed of the possibility that the imaging techniques may have also been changed. One of the main problems in image processing is to determine the spatial relation between such images. The corresponding process of finding the spatial alignment is called “registration”. In this work, we study the optimization problem which corresponds to the registration task. Especially, we exploit the Lie group structure of the set of transformations to construct efficient, intrinsic algorithms. We also apply the algorithms to medical registration tasks. However, the methods developed are not restricted to the field of medical image processing. We also have a closer look at more general forms of optimization problems and show connections to related tasks. N2 - Wir betrachten Problemstellungen, in denen zwei Bilder von ein und demselben Objekt aufgenommen wurden. Nach der ersten Aufnahme hat sich allerdings das Objekt bewegt oder deformiert, so dass es sich in den nächsten Bildern auf eine andere Weise darstellt. Zudem kann sich die Aufnahmetechnik geändert haben. Eine der Hauptprobleme in der Bildverarbeitung ist es, die räumliche Korrespondenz zwischen solchen Bildern zu bestimmen. Die zugehörige Aufgabe, eine solche räumliche Übereinstimmung zu finden, nennt man "Registrierung". In dieser Arbeit untersuchen wir das mit der Registrierung verbundene Optimierungsproblem. Insbesondere nutzen wir die Lie-Gruppen-Struktur der Menge der zulässigen Transformationen aus, um effiziente, intrinsische Argorithmen zu entwickeln. Wir wenden diese dann auf Probleme der medizinischen Bildregistrierung an, jedoch sind unsere Methoden nicht auf dieses Feld beschränkt. Wir werfen auch einen genaueren Blick auf eine allgemeinere Form von Optimierungsproblemen und zeigen Verknüpfungen zu verwandten Fragestellungen auf. KW - Newton-Verfahren KW - Registrierung KW - Stochastische Optimierung KW - Newton Methods KW - Image Registration KW - Stochastic Algorithms KW - Optimization on Lie Groups Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-71490 ER - TY - THES A1 - Schäfer, Dirk T1 - Globale Selbstlokalisation autonomer mobiler Roboter - Ein Schlüsselproblem der Service-Robotik T1 - The global self-localisation problem - a key problem in the field of service robotics N2 - Die Dissertation behandelt die Problemstellung der globalen Selbstlokalisation autonomer mobiler Roboter, welche folgendermaßen beschrieben werden kann: Ein mobiler Roboter, eingesetzt in einem Gebäude, kann unter Umständen das Wissen über seinen Standort verlieren. Man geht nun davon aus, dass dem Roboter eine Gebäudekarte als Modell zur Verfügung steht. Mit Hilfe eines Laser-Entfernungsmessers kann das mobile Gerät neue Informationen aufnehmen und damit bei korrekter Zuordnung zur Modellkarte geeignete hypothetische Standorte ermitteln. In der Regel werden diese Positionen aber mehrdeutig sein. Indem sich der Roboter intelligent in seiner Einsatzumgebung bewegt, kann er die ursprünglichen Sensordaten verifizieren und ermittelt im besten Fall seine tatsächliche Position.Für diese Problemstellung wird ein neuer Lösungsansatz in Theorie und Praxis präsentiert, welcher die jeweils aktuelle lokale Karte und damit alle Sensordaten mittels feature-basierter Matchingverfahren auf das Modell der Umgebung abbildet. Ein Explorationsalgorithmus bewegt den Roboter während der Bewegungsphase autonom zu Sensorpunkten, welche neue Informationen bereitstellen. Während der Bewegungsphase werden dabei die bisherigen hypothetischen Positionen bestärkt oder geschwächt, sodaß nach kurzer Zeit eine dominante Position, die tatsächliche Roboterposition,übrigbleibt. N2 - This thesis is dealing with the global self-localisation problem, which is known to be one of the hardest problems among autonomous mobile systems. The problem can be described as follows: A mobile robot agent has a map of the environment but does not know its position. It is equipped with ultransonic sensors and a laser range finder as main sensor. The goal of the robot agent is to recognize its true position within the environment.The level of complexity of this task increases with the size and also with the level of symmetry of the indoor environment. To cope with the problem a new approach will be presented in this thesis using state of the art map building and exploration algorithms as well as feature based localisation methods. Decomposition of the global map into a number of submaps, informative feature selection and multiple submap localisation queries ensure the road of success. The capability of the approach to global self-localising the robot is pointed out by several practical studies. KW - Mobiler Roboter KW - Autonomer Roboter KW - Lokalisation KW - Globale Selbstlokalisation KW - Mobile Roboter KW - Kartierung KW - Feature-Matching KW - Gllobal self-localisation KW - mobile robots KW - slam KW - feature-matching Y1 - 2003 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-7601 ER - TY - THES A1 - Selbach, Stefan T1 - Hybride bitparallele Volltextsuche T1 - Hybrid Bit-parallel Full-text Search N2 - Der große Vorteil eines q-Gramm Indexes liegt darin, dass es möglich ist beliebige Zeichenketten in einer Dokumentensammlung zu suchen. Ein Nachteil jedoch liegt darin, dass bei größer werdenden Datenmengen dieser Index dazu neigt, sehr groß zu werden, was mit einem deutlichem Leistungsabfall verbunden ist. In dieser Arbeit wird eine neuartige Technik vorgestellt, die die Leistung eines q-Gramm Indexes mithilfe zusätzlicher M-Matrizen für jedes q-Gramm und durch die Kombination mit einem invertierten Index erhöht. Eine M-Matrix ist eine Bit-Matrix, die Informationen über die Positionen eines q-Gramms enthält. Auch bei der Kombination von zwei oder mehreren Q-Grammen bieten diese M-Matrizen Informationen über die Positionen der Kombination. Dies kann verwendet werden, um die Komplexität der Zusammenführung der q-Gramm Trefferlisten für eine gegebene Suchanfrage zu reduzieren und verbessert die Leistung des n-Gramm-invertierten Index. Die Kombination mit einem termbasierten invertierten Index beschleunigt die durchschnittliche Suchzeit zusätzlich und vereint die Vorteile beider Index-Formate. Redundante Informationen werden in dem q-Gramm Index reduziert und weitere Funktionalität hinzugefügt, wie z.B. die Bewertung von Treffern nach Relevanz, die Möglichkeit, nach Konzepten zu suchen oder Indexpartitionierungen nach Wichtigkeit der enthaltenen Terme zu erstellen. N2 - The major advantage of the n-gram inverted index is the possibility to locate any given substring in a document collection. Nevertheless, the n-gram inverted index also has its drawbacks: If the collections are getting bigger, this index tends to be very large and the performance drops significantly. A novel technique is proposed to enhance the performance of an n-gram inverted index by using additional m-matrixes for each n-gram and by combining it with an inverted index. An m-matrix is a bit matrix containing information about the positions of an n-gram. When combining two or more n-grams, these m-matrixes provide information about the positions of the combination. This can be used to reduce the complexity of merging the n-gram postings lists for a given search and improves the performance of the n-gram inverted index. The combination with a term based inverted index speeds up the average search time even more and combines the benefits of both index formats. Redundant information is reduced in the n-gram index and further functionality is added like the ranking of hits, the possibility to search for concepts and to create index partitions according to the relevance of the contained terms. KW - Information Retrieval KW - Information-Retrieval-System KW - Suchverfahren KW - Invertierte Liste KW - n-Gramm KW - q-Gramm KW - Volltextsuche KW - Bit Parallelität KW - Konzeptsuche KW - q-gram KW - n-gram KW - bit-parallel KW - full-text search KW - concept search Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-66476 ER - TY - RPRT A1 - Sertbas Bülbül, Nurefsan A1 - Ergenc, Doganalp A1 - Fischer, Mathias T1 - Evaluating Dynamic Path Reconfiguration for Time Sensitive Networks T2 - Würzburg Workshop on Next-Generation Communication Networks (WueWoWas'22) N2 - In time-sensitive networks (TSN) based on 802.1Qbv, i.e., the time-aware Shaper (TAS) protocol, precise transmission schedules and, paths are used to ensure end-to-end deterministic communication. Such resource reservations for data flows are usually established at the startup time of an application and remain untouched until the flow ends. There is no way to migrate existing flows easily to alternative paths without inducing additional delay or wasting resources. Therefore, some of the new flows cannot be embedded due to capacity limitations on certain links which leads to sub-optimal flow assignment. As future networks will need to support a large number of lowlatency flows, accommodating new flows at runtime and adapting existing flows accordingly becomes a challenging problem. In this extended abstract we summarize a previously published paper of us [1]. We combine software-defined networking (SDN), which provides better control of network flows, with TSN to be able to seamlessly migrate time-sensitive flows. For that, we formulate an optimization problem and propose different dynamic path configuration strategies under deterministic communication requirements. Our simulation results indicate that regularly reconfiguring the flow assignments can improve the latency of time-sensitive flows and can increase the number of flows embedded in the network around 4% in worst-case scenarios while still satisfying individual flow deadlines. KW - Datennetz KW - SDN KW - dynamic flow migration KW - reconfiguration KW - TSN KW - path computation Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-280743 ER - TY - JOUR A1 - Seufert, Anika A1 - Poignée, Fabian A1 - Hoßfeld, Tobias A1 - Seufert, Michael T1 - Pandemic in the digital age: analyzing WhatsApp communication behavior before, during, and after the COVID-19 lockdown JF - Humanities and Social Sciences Communications N2 - The strict restrictions introduced by the COVID-19 lockdowns, which started from March 2020, changed people’s daily lives and habits on many different levels. In this work, we investigate the impact of the lockdown on the communication behavior in the mobile instant messaging application WhatsApp. Our evaluations are based on a large dataset of 2577 private chat histories with 25,378,093 messages from 51,973 users. The analysis of the one-to-one and group conversations confirms that the lockdown severely altered the communication in WhatsApp chats compared to pre-pandemic time ranges. In particular, we observe short-term effects, which caused an increased message frequency in the first lockdown months and a shifted communication activity during the day in March and April 2020. Moreover, we also see long-term effects of the ongoing pandemic situation until February 2021, which indicate a change of communication behavior towards more regular messaging, as well as a persisting change in activity during the day. The results of our work show that even anonymized chat histories can tell us a lot about people’s behavior and especially behavioral changes during the COVID-19 pandemic and thus are of great relevance for behavioral researchers. Furthermore, looking at the pandemic from an Internet provider perspective, these insights can be used during the next pandemic, or if the current COVID-19 situation worsens, to adapt communication networks to the changed usage behavior early on and thus avoid network congestion. KW - cultural and media studies KW - information systems and information technology KW - science, technology and society Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-300261 VL - 9 ER - TY - JOUR A1 - Seufert, Anika A1 - Poignée, Fabian A1 - Seufert, Michael A1 - Hoßfeld, Tobias T1 - Share and multiply: modeling communication and generated traffic in private WhatsApp groups JF - IEEE Access N2 - Group-based communication is a highly popular communication paradigm, which is especially prominent in mobile instant messaging (MIM) applications, such as WhatsApp. Chat groups in MIM applications facilitate the sharing of various types of messages (e.g., text, voice, image, video) among a large number of participants. As each message has to be transmitted to every other member of the group, which multiplies the traffic, this has a massive impact on the underlying communication networks. However, most chat groups are private and network operators cannot obtain deep insights into MIM communication via network measurements due to end-to-end encryption. Thus, the generation of traffic is not well understood, given that it depends on sizes of communication groups, speed of communication, and exchanged message types. In this work, we provide a huge data set of 5,956 private WhatsApp chat histories, which contains over 76 million messages from more than 117,000 users. We describe and model the properties of chat groups and users, and the communication within these chat groups, which gives unprecedented insights into private MIM communication. In addition, we conduct exemplary measurements for the most popular message types, which empower the provided models to estimate the traffic over time in a chat group. KW - communication models KW - group-based communication KW - mobile instant messaging KW - mobile messaging application KW - private chat groups KW - WhatsApp Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-349430 VL - 11 ER - TY - JOUR A1 - Seufert, Anika A1 - Schröder, Svenja A1 - Seufert, Michael T1 - Delivering User Experience over Networks: Towards a Quality of Experience Centered Design Cycle for Improved Design of Networked Applications JF - SN Computer Science N2 - To deliver the best user experience (UX), the human-centered design cycle (HCDC) serves as a well-established guideline to application developers. However, it does not yet cover network-specific requirements, which become increasingly crucial, as most applications deliver experience over the Internet. The missing network-centric view is provided by Quality of Experience (QoE), which could team up with UX towards an improved overall experience. By considering QoE aspects during the development process, it can be achieved that applications become network-aware by design. In this paper, the Quality of Experience Centered Design Cycle (QoE-CDC) is proposed, which provides guidelines on how to design applications with respect to network-specific requirements and QoE. Its practical value is showcased for popular application types and validated by outlining the design of a new smartphone application. We show that combining HCDC and QoE-CDC will result in an application design, which reaches a high UX and avoids QoE degradation. KW - user experience KW - human-centered design KW - design cycle KW - application design KW - quality of experience Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-271762 SN - 2661-8907 VL - 2 IS - 6 ER - TY - RPRT A1 - Simon, Manuel A1 - Gallenmüller, Sebastian A1 - Carle, Georg T1 - Never Miss Twice - Add-On-Miss Table Updates in Software Data Planes T2 - KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2023 (WueWoWAS’23) N2 - State Management at line rate is crucial for critical applications in next-generation networks. P4 is a language used in software-defined networking to program the data plane. The data plane can profit in many circumstances when it is allowed to manage its state without any detour over a controller. This work is based on a previous study by investigating the potential and performance of add-on-miss insertions of state by the data plane. The state keeping capabilities of P4 are limited regarding the amount of data and the update frequency. We follow the tentative specification of an upcoming portable-NIC-architecture and implement these changes into the software P4 target T4P4S. We show that insertions are possible with only a slight overhead compared to lookups and evaluate the influence of the rate of insertions on their latency. KW - SDN KW - state management KW - P4 KW - Add-on-Miss Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-322071 ER - TY - JOUR A1 - Singh, Amit K. A1 - Kingston, Joseph J. A1 - Gupta, Shishir K. A1 - Batra, Harsh V. T1 - Recombinant Bivalent Fusion Protein rVE Induces CD4+ and CD8+ T-Cell Mediated Memory Immune Response for Protection Against Yersinia enterocolitica Infection JF - Frontiers in Microbiology N2 - Studies investigating the correlates of immune protection against Yersinia infection have established that both humoral and cell mediated immune responses are required for the comprehensive protection. In our previous study, we established that the bivalent fusion protein (rVE) comprising immunologically active regions of Y pestis LcrV (100-270 aa) and YopE (50-213 aa) proteins conferred complete passive and active protection against lethal Y enterocolitica 8081 challenge. In the present study, cohort of BALB/c mice immunized with rVE or its component proteins rV, rE were assessed for cell mediated immune responses and memory immune protection against Y enterocolitica 8081 rVE immunization resulted in extensive proliferation of both CD4 and CD8 T cell subsets; significantly high antibody titer with balanced IgG1: IgG2a/IgG2b isotypes (1:1 ratio) and up regulation of both Th1 (INF-\(\alpha\), IFN-\(\gamma\), IL 2, and IL 12) and Th2 (IL 4) cytokines. On the other hand, rV immunization resulted in Th2 biased IgG response (11:1 ratio) and proliferation of CD4+ T-cell; rE group of mice exhibited considerably lower serum antibody titer with predominant Th1 response (1:3 ratio) and CD8+ T-cell proliferation. Comprehensive protection with superior survival (100%) was observed among rVE immunized mice when compared to the significantly lower survival rates among rE (37.5%) and rV (25%) groups when IP challenged with Y enterocolitica 8081 after 120 days of immunization. Findings in this and our earlier studies define the bivalent fusion protein rVE as a potent candidate vaccine molecule with the capability to concurrently stimulate humoral and cell mediated immune responses and a proof of concept for developing efficient subunit vaccines against Gram negative facultative intracellular bacterial pathogens. KW - I-tasser KW - Yersinia enterocolitica KW - memory immune responses KW - cytokine profiling KW - CD8+T cells KW - CD4+T cells KW - recombinant protein rVE KW - resistance KW - pneumonic plague KW - pestis infection KW - nonhuman-primates KW - III secretion KW - V-antigen KW - mice KW - vaccine Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-136114 VL - 6 IS - 1407 ER - TY - THES A1 - Somody, Joseph Christian Campbell T1 - Leveraging deep learning for identification and structural determination of novel protein complexes from \(in\) \(situ\) electron cryotomography of \(Mycoplasma\) \(pneumoniae\) T1 - Tiefenlernen als Werkzeug zur Identifizierung und Strukturbestimmung neuer Proteinkomplexe aus der \(in\)-\(situ\)-Elektronenkryotomographie von \(Mycoplasma\) \(pneumoniae\) N2 - The holy grail of structural biology is to study a protein in situ, and this goal has been fast approaching since the resolution revolution and the achievement of atomic resolution. A cell's interior is not a dilute environment, and proteins have evolved to fold and function as needed in that environment; as such, an investigation of a cellular component should ideally include the full complexity of the cellular environment. Imaging whole cells in three dimensions using electron cryotomography is the best method to accomplish this goal, but it comes with a limitation on sample thickness and produces noisy data unamenable to direct analysis. This thesis establishes a novel workflow to systematically analyse whole-cell electron cryotomography data in three dimensions and to find and identify instances of protein complexes in the data to set up a determination of their structure and identity for success. Mycoplasma pneumoniae is a very small parasitic bacterium with fewer than 700 protein-coding genes, is thin enough and small enough to be imaged in large quantities by electron cryotomography, and can grow directly on the grids used for imaging, making it ideal for exploratory studies in structural proteomics. As part of the workflow, a methodology for training deep-learning-based particle-picking models is established. As a proof of principle, a dataset of whole-cell Mycoplasma pneumoniae tomograms is used with this workflow to characterize a novel membrane-associated complex observed in the data. Ultimately, 25431 such particles are picked from 353 tomograms and refined to a density map with a resolution of 11 Å. Making good use of orthogonal datasets to filter search space and verify results, structures were predicted for candidate proteins and checked for suitable fit in the density map. In the end, with this approach, nine proteins were found to be part of the complex, which appears to be associated with chaperone activity and interact with translocon machinery. Visual proteomics refers to the ultimate potential of in situ electron cryotomography: the comprehensive interpretation of tomograms. The workflow presented here is demonstrated to help in reaching that potential. N2 - Der heilige Gral der Strukturbiologie ist die Untersuchung eines Proteins in situ, und dieses Ziel ist seit der Auflösungsrevolution und dem Erreichen der atomaren Auflösung in greifbare Nähe gerückt. Das Innere einer Zelle ist keine verdünnte Umgebung, und Proteine haben sich so entwickelt, dass sie sich falten und so funktionieren, wie es in dieser Umgebung erforderlich ist; daher sollte die Untersuchung einer zellulären Komponente idealerweise die gesamte Komplexität der zellulären Umgebung umfassen. Die Abbildung ganzer Zellen in drei Dimensionen mit Hilfe der Elektronenkryotomographie ist die beste Methode, um dieses Ziel zu erreichen, aber sie ist mit einer Beschränkung der Probendicke verbunden und erzeugt verrauschte Daten, die sich nicht für eine direkte Analyse eignen. In dieser Dissertation wird ein neuartiger Workflow zur systematischen dreidimensionalen Analyse von Ganzzell-Elektronenkryotomographiedaten und zur Auffindung und Identifizierung von Proteinkomplexen in diesen Daten entwickelt, um eine erfolgreiche Bestimmung ihrer Struktur und Identität zu ermöglichen. Mycoplasma pneumoniae ist ein sehr kleines parasitäres Bakterium mit weniger als 700 proteinkodierenden Genen. Es ist dünn und klein genug, um in grossen Mengen durch Elektronenkryotomographie abgebildet zu werden, und kann direkt auf den für die Abbildung verwendeten Gittern wachsen, was es ideal für Sondierungsstudien in der strukturellen Proteomik macht. Als Teil des Workflows wird eine Methodik für das Training von Deep-Learning-basierten Partikelpicken-Modellen entwickelt. Als Proof-of-Principle wird ein Dataset von Ganzzell-Tomogrammen von Mycoplasma pneumoniae mit diesem Workflow verwendet, um einen neuartigen membranassoziierten Komplex zu charakterisieren, der in den Daten beobachtet wurde. Insgesamt wurden 25431 solcher Partikel aus 353 Tomogrammen gepickt und zu einer Dichtekarte mit einer Auflösung von 11 Å verfeinert. Unter Verwendung orthogonaler Datensätze zur Filterung des Suchraums und zur Überprüfung der Ergebnisse wurden Strukturen für Protein-Kandidaten vorhergesagt und auf ihre Eignung für die Dichtekarte überprüft. Letztendlich wurden mit diesem Ansatz neun Proteine als Bestandteile des Komplexes gefunden, der offenbar mit der Chaperonaktivität in Verbindung steht und mit der Translocon-Maschinerie interagiert. Das ultimative Potenzial der In-situ-Elektronenkryotomographie – die umfassende Interpretation von Tomogrammen – wird als visuelle Proteomik bezeichnet. Der hier vorgestellte Workflow soll dabei helfen, dieses Potenzial auszuschöpfen. KW - Kryoelektronenmikroskopie KW - Tomografie KW - Mycoplasma pneumoniae KW - Deep learning KW - cryo-EM KW - cryo-ET KW - tomography KW - mycoplasma KW - pneumoniae KW - deep learning KW - particle picking KW - membrane protein KW - visual proteomics Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-313447 ER -