@phdthesis{Grob2022,
  author    = {Grob, Robin},
  title     = {The Function of Learning Walks of \({Cataglyphis Ants}\): Behavioral and Neuronal Analyses},
  doi       = {10.25972/OPUS-29017},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-290173},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {Humans and animals alike use the sun, the moon, and the stars to guide their ways. However, the position of celestial cues changes depending on daytime, season, and place on earth. To use these celestial cues for reliable navigation, the rotation of the sky has to be compensated. While humans invented complicated mechanisms like the Antikythera mechanism to keep track of celestial movements, animals can only rely on their brains. The desert ant Cataglyphis is a prime example of an animal using celestial cues for navigation. Using the sun and the related skylight polarization pattern as a compass, and a step integrator for distance measurements, it can determine a vector always pointing homewards. This mechanism is called path integration. Since the sun's position and, therefore, also the polarization pattern changes throughout the day, Cataglyphis have to correct this movement. If they did not compensate for time, the ants' compass would direct them in different directions in the morning and the evening. Thus, the ants have to learn the solar ephemeris before their far-reaching foraging trips. To do so, Cataglyphis ants perform a well-structured learning-walk behavior during the transition phase from indoor worker to outdoor forager. While walking in small loops around the nest entrance, the ants repeatedly stop their forward movements to perform turns. These can be small walked circles (voltes) or tight turns about the ants' body axes (pirouettes). During pirouettes, the ants gaze back to their nest entrance during stopping phases. These look backs provide a behavioral read-out for the state of the path integrator. The ants "tell" the observer where they think their nest is, by looking back to it. Pirouettes are only performed by Cataglyphis ants inhabiting an environment with a prominent visual panorama. This indicates, that pirouettes are performed to learn the visual panorama. Voltes, on the other hand, might be used for calibrating the celestial compass of the ants. In my doctoral thesis, I employed a wide range of state-of-the-art techniques from different disciplines in biology to gain a deeper understanding of how navigational information is acquired, memorized, used, and calibrated during the transition phase from interior worker to outdoor forager. I could show, that celestial orientation cues that provide the main compass during foraging, do not guide the ants during the look-backbehavior of initial learning walks. Instead Cataglyphis nodus relies on the earth's magnetic field as a compass during this early learning phase. While not guiding the ants during their first walks outside of the nest, excluding the ants from perceiving the natural polarization pattern of the skylight has significant consequences on learning-related plasticity in the ants' brain. Only if the ants are able to perform their learning-walk behavior under a skylight polarization pattern that changes throughout the day, plastic neuronal changes in high-order integration centers are induced. Especially the mushroom bogy collar, a center for learning and memory, and the central complex, a center for orientation and motor control, showed an increase in volume after learning walks. This underlines the importance of learning walks for calibrating the celestial compass. The magnetic compass might provide the necessary stable reference system for the ants to calibrate their celestial compass and learn the position of landmark information. In the ant brain, visual information from the polarization-sensitive ocelli converge in tight apposition with neuronal afferents of the mechanosensitive Johnston's organ in the ant's antennae. This makes the ants' antennae an interesting candidate for studying the sensory bases of compass calibration in Cataglyphis ants. The brain of the desert navigators is well adapted to successfully accomplish their navigational needs. Females (gynes and workers) have voluminous mushroom bodies, and the synaptic complexity to store large amount of view-based navigational information, which they acquire during initial learning walks. The male Cataglyphis brain is better suited for innate behaviors that support finding a mate. The results of my thesis show that the well adapted brain of C. nodus ants undergoes massive structural changes during leaning walks, dependent on a changing celestial polarization pattern. This underlies the essential role of learning walks in the calibration of orientation systems in desert ants.},
  subject      = {Cataglyphis},
  language  = {en}
}
@phdthesis{Fischer2021,
  author    = {Fischer, Gregor},
  title     = {Navigations- und Ultraschallgest{\"u}tzte Punktion der Leistenarterie beim transfemoralen Aortenklappenersatz},
  doi       = {10.25972/OPUS-23158},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-231586},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Transcatheter aortic valve replacement (TAVR) is an established procedure for treatment of aortic stenosis. In transfemoral TAVR local vascular complications at the puncture site are still an important issue and responsible for the majority of complications. To ensure safe puncture in a non-calcified vessel segment a new navigation technique with ultrasound guidance has been developed. We compared 67 consecutive patients undergoing TAVR using our new approach with 67 patients with fluoroscopic punction.},
  subject      = {Aortenklappenersatz},
  language  = {de}
}
@phdthesis{Auinger2013,
  author    = {Auinger, Julia},
  title     = {Gezielte linksventrikuläre Endomyokardbiopsie unter Einsatz eines 3D Mapping-Systems und einer navigierten steuerbaren Schleuse ‒ Entwicklung und experimentelle Validierung der Methode},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-90321},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2013},
  abstract  = {Zielsetzung: In dieser Machbarkeitsstudie evaluierten wir den aktuellen Standard der linksventrikul{\"a}ren Endomyokardbiopsie in einem Modellversuch. Wir entwickelten und {\"u}berpr{\"u}ften m{\"o}gliche Verbesserungen hinsichtlich ihrer Sicherheit und Punktionsgenauigkeit, indem wir eine steuerbare Schleuse und ein 3D Mapping-System zum Einsatz brachten. Hintergrund: Die Endomyokardbiopsie gilt als Goldstandard zur Diagnostik von Myokarditiden und Kardiomyopathien, da sie histochemische, histologische und molekularbiologische Analysen ermöglicht, die f{\"u}r eine korrekte Diagnose und Therapie wichtig sind. Die Methodik hat eine verhältnismäßig geringe Sensitivität und einen niedrigen negativen prädiktiven Wert, da das Myokard derzeit unter Röntgendurchleuchtung biopsiert wird, ohne eine genaue Orientierung im dreidimensionalen Raum oder eine Kenntnis der z.T. diskontinuierlich betroffenen Myokardareale zu haben (sogenannter „sampling error"). Methoden: Wir testeten die Steuerbarkeit und die Punktionsgenauigkeit der Endomyokardbiopsie im Modellversuch, indem wiederholt Biopsien von acht verschiedenen linksventrikul{\"a}ren Herzregionen genommen werden. In einer dreiarmigen Studie optimierten wir zum einen die invasiv-apparative Ausr{\"u}stung und zum anderen die verf{\"u}gbare Bildgebungsmodalit{\"a}t. Der Kontrollversuch I repr{\"a}sentiert eine Analyse des aktuellen Standards, da hier Biopsien mit konventionellen F{\"u}hrungskathetern unter R{\"o}ntgendurchleuchtung erfolgen. Der Kontrollversuch II untersucht, ob mittels einer steuerbaren Schleuse unter konventioneller Bildgebung eine Verbesserung erzielt werden kann. Im dritten Teil der Studie wurde die R{\"o}ntgendurchleuchtung durch ein 3D elektroanatomisches Mapping-System ersetzt. Hiermit kann erstmalig die Machbarkeit der Navigation einer steuerbaren Schleuse in einem 3D Mapping-System gepr{\"u}ft werden. Ergebnisse: Jeder der eingesetzten konventionellen F{\"u}hrungskatheter ist f{\"u}r die Biopsie einer bestimmten Herzregionen geeignet, jedoch hat die konventionelle Methodik bei wiederholten Messungen allgemein eine niedrige Pr{\"a}zision (JR 4.0 F{\"u}hrungskatheter: 17,4 ± 4 mm, AL 1.0 F{\"u}hrungskatheter: 18,7 ± 5,7 mm, EBU 3.5 F{\"u}hrungskatheter: 18,3 ± 8,2 mm). Durch den Einsatz der neu entwickelten steuerbaren Schleuse konnten einige der gew{\"u}nschten Stellen zwar korrekter biopsiert werden, aber eine allgemein sichere Ansteuerung aller Positionen war damit noch nicht m{\"o}glich (9,5 ± 5,8 mm). Die bildliche Darstellung der steuerbaren Schleuse im 3D Mapping-System gelang sehr gut, die Biopsiezange konnte mit der Schleuse leicht und mit einer h{\"o}heren Pr{\"a}zision an fast alle gew{\"u}nschten Herzregionen navigiert werden (3,6 ± 2 mm). Fazit: Die hier vorgelegte Machbarkeitsstudie zeigt, dass der Einsatz einer neuentwickelten steuerbaren Schleuse in Kombination mit einem 3D Mapping-System m{\"o}glich und erfolgversprechend ist. Die Ergebnisse der Biopsien im elektroanatomischen Mapping-Versuch wiesen im Mittel eine deutlich geringere Abweichung beim wiederholten Ansteuern der jeweilig gew{\"u}nschten Zielregion auf. Mittels der neuentwickelten Technik kann somit die Endomyokardbiopsie im Vergleich zum Standardverfahren pr{\"a}ziser und mit einer potentiell h{\"o}heren Patientensicherheit durchgef{\"u}hrt werden.},
  subject      = {Myokard},
  language  = {de}
}
@phdthesis{Pahl2011,
  author    = {Pahl, Mario},
  title     = {Honeybee Cognition: Aspects of Learning, Memory and Navigation in a Social Insect},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-66165},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2011},
  abstract  = {Honeybees (Apis mellifera) forage on a great variety of plant species, navigate over large distances to crucial resources, and return to communicate the locations of food sources and potential new nest sites to nest mates using a symbolic dance language. In order to achieve this, honeybees have evolved a rich repertoire of adaptive behaviours, some of which were earlier believed to be restricted to vertebrates. In this thesis, I explore the mechanisms involved in honeybee learning, memory, numerical competence and navigation. The findings acquired in this thesis show that honeybees are not the simple reflex automats they were once believed to be. The level of sophistication I found in the bees' memory, their learning ability, their time sense, their numerical competence and their navigational abilities are surprisingly similar to the results obtained in comparable experiments with vertebrates. Thus, we should reconsider the notion that a bigger brain automatically indicates higher intelligence.},
  subject      = {Biene},
  language  = {en}
}