@phdthesis{Hugo2023,
  author    = {Hugo, Julian},
  title     = {'Signal-close-to-noise' calcium activity reflects neuronal excitability},
  doi       = {10.25972/OPUS-29260},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-292605},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {Chronic pain conditions are a major reason for the utilization of the health care system. Inflammatory pain states can persist facilitated by peripheral sensitization of nociceptors. The voltage-gated sodium channel 1.9 (NaV1.9) is an important regulator of neuronal excitability and is involved in inflammation-induced pain hypersensitivity. Recently, oxidized 1-palmitoyl-2-arachidonoyl-sn-glycerol-3-phosphatidylcholine (OxPAPC) was identified as a mediator of acute inflammatory pain and persistent hyperalgesia, suggesting an involvement in proalgesic cascades and peripheral sensitization. Peripheral sensitization implies an increase in neuronal excitability. This thesis aims to characterize spontaneous calcium activity in neuronal compartments as a proxy to investigate neuronal excitability, making use of the computational tool Neural Activity Cubic (NA3). NA3 allows automated calcium activity event detection of signal-close-to-noise calcium activity and evaluation of neuronal activity states. Additionally, the influence of OxPAPC and NaV1.9 on the excitability of murine dorsal root ganglion (DRG) neurons and the effect of OxPAPC on the response of DRG neurons towards other inflammatory mediators (prostaglandin E2, histamine, and bradykinin) is investigated. Using calcium imaging, the presence of spontaneous calcium activity in murine DRG neurons was established. NA3 was used to quantify this spontaneous calcium activity, which revealed decreased activity counts in axons and somata of NaV1.9 knockout (KO) neurons compared to wildtype (WT). Incubation of WT DRG neurons with OxPAPC before calcium imaging did not show altered activity counts compared to controls. OxPAPC incubation also did not modify the response of DRG neurons treated with inflammatory mediators. However, the variance ratio computed by NA3 conclusively allowed to determine neuronal activity states. In conclusion, my findings indicate an important function of NaV1.9 in determining the neuronal excitability of DRG neurons in resting states. OxPAPC exposition does not influence neuronal excitability nor sensitizes neurons for other inflammatory mediators. This evidence reduces the primary mechanism of OxPAPC-induced hyperalgesia to acute effects. Importantly, it was possible to establish an approach for unbiased excitability quantification of DRG neurons by calcium activity event detection and calcium trace variance analysis by NA3. It was possible to show that signal-close-to-noise calcium activity reflects neuronal excitability states.},
  subject      = {Entz{\"u}ndung},
  language  = {en}
}
@phdthesis{Gregor2008,
  author    = {Gregor, Thomas},
  title     = {{0,1}-Matrices with Rectangular Rule},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-28389},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2008},
  abstract  = {The incidence matrices of many combinatorial structures satisfy the so called rectangular rule, i.e., the scalar product of any two lines of the matrix is at most 1. We study a class of matrices with rectangular rule, the regular block matrices. Some regular block matrices are submatrices of incidence matrices of finite projective planes. Necessary and sufficient conditions are given for regular block matrices, to be submatrices of projective planes. Moreover, regular block matrices are related to another combinatorial structure, the symmetric configurations. In particular, it turns out, that we may conclude the existence of several symmetric configurations from the existence of a projective plane, using this relationship.},
  subject      = {Projektive Ebene},
  language  = {en}
}
@phdthesis{Schumm2008,
  author    = {Schumm, Marcel},
  title     = {ZnO-based semiconductors studied by Raman spectroscopy: semimagnetic alloying, doping, and nanostructures},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-37045},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2008},
  abstract  = {ZnO-based semiconductors were studied by Raman spectroscopy and complementary methods (e.g. XRD, EPS) with focus on semimagnetic alloying with transition metal ions, doping (especially p-type doping with nitrogen as acceptor), and nanostructures (especially wet-chemically synthesized nanoparticles).},
  subject      = {Wide-gap-Halbleiter},
  language  = {en}
}
@phdthesis{Wagner2020,
  author    = {Wagner, Leonard},
  title     = {Zinc homeostasis in megakaryocytes},
  doi       = {10.25972/OPUS-21452},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-214526},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2020},
  abstract  = {Zinc is an essential trace element for all living organisms. In mammals, including humans and mice, it is required for normal growth, development, hematopoiesis and immune defense. This thesis investigates the influence of zinc on the development of megakaryocytes (MKs), the cells responsible for bone marrow-derived platelet production. Furthermore, a detailed analysis of the expression of zinc import and export transporters (Slc39a/Slc30a genes) is carried out, firstly over the course of MK differentiation and secondly dependent on extracellular zinc.},
  subject      = {Zink},
  language  = {en}
}
@phdthesis{Spenst2017,
  author    = {Spenst, Peter},
  title     = {Xylylene Bridged Perylene Bisimide Cyclophanes and Macrocycles},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-139015},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {This work is concerned with the syntheses and photophysical properties of para-xylylene bridged macrocycles nPBI with ring sizes from two to nine PBI units, as well as the complexation of polycyclic aromatic guest compounds. With a reduced but substantial fluorescence quantum yield of 21\% (in CHCl3) the free host 2PBI(4-tBu)4 can be used as a dual fluorescence probe. Upon encapsulation of rather electron-poor guests the fluorescence quenching interactions between the chromophores are prevented, leading to a significant fluorescence enhancement to > 90\% ("turn-on"). On the other hand, the addition of electron-rich guest molecules induces an electron transfer from the guest to the electron-poor PBI chromophores and thus quenches the fluorescence entirely ("turn-off"). The photophysical properties of the host-guest complexes were studied by transient absorption spectroscopy. These measurements revealed that the charge transfer between guest and 2PBI(4-tBu)4 occurs in the "normal region" of the Marcus-parabola with the fastest charge separation rate for perylene. In contrast, the charge recombination back to the PBI ground state lies far in the "inverted region" of the Marcus-parabola. Beside complexation of planar aromatic hydrocarbons into the cavity of the cyclophanes an encapsulation of fullerene into the cyclic trimer 3PBI(4-tBu)4 was observed. 3PBI(4-tBu)4 provides a tube-like structure in which the PBI subunits represent the walls of those tubes. The cavity has the optimal size for hosting fullerenes, with C70 fitting better than C60 and a binding constant that is higher by a factor of 10. TA spectroscopy in toluene that was performed on the C60@3PBI(4-tBu)4 complex revealed two energy transfer processes. The first one comes from the excited PBI to the fullerene, which subsequently populates the triplet state. From the fullerene triplet state a second energy transfer occurs back to the PBI to generate the PBI triplet state. In all cycles that were studied by TA spectroscopy, symmetry-breaking charge separation (SB-CS) was observed in dichloromethane. This process is fastest within the PBI cyclophane 2PBI(4-tBu)4 and slows down for larger cycles, suggesting that the charge separation takes place through space and not through bonds. The charges then recombine to the PBI triplet state via a radical pair intersystem crossing (RP-ISC) mechanism, which could be used to generate singlet oxygen in yields of ~20\%. By changing the solvent to toluene an intramolecular folding of the even-numbered larger cycles was observed that quenches the fluorescence and increases the 0-1 transition band in the absorption spectra. Force field calculations of 4PBI(4-tBu)4 suggested a folding into pairs of dimers, which explains the remarkable odd-even effect with respect to the number of connected PBI chromophores and the resulting alternation in the absorption and fluorescence properties. Thus, the even-numbered macrocycles can fold in a way that all chromophores are in a paired arrangement, while the odd-numbered cycles have open conformations (3PBI(4-tBu)4, 5PBI(4-tBu)4, 7PBI(4-tBu)4) or at least additional unpaired PBI unit (9PBI(4-tBu)4). With these experiments we could for the first time give insights in the interactions between cyclic PBI hosts and aromatic guest molecules. Associated with the encapsulation of guest molecules a variety of possible applications can be envisioned, like fluorescence sensing, chiral recognition and photodynamic therapy by singlet oxygen generation. Particularly, these macrocycles provide photophysical relaxation pathways of PBIs, like charge separation and recombination and triplet state formation that are hardly feasible in monomeric PBI dyes. Furthermore, diverse compound specific features were found, like the odd-even effect in the folding process or the transition of superficial nanostructures of the tetrameric cycle influenced by the AFM tip. The comprehensive properties of these macrocycles provide the basis for further oncoming studies and can serve as an inspiration for the synthesis of new macrocyclic compounds.},
  subject      = {Supramolekulare Chemie},
  language  = {en}
}
@phdthesis{GraetzgebDittmann2022,
  author    = {Graetz [geb. Dittmann], Jonas},
  title     = {X-Ray Dark-Field Tensor Tomography : a Hitchhiker's Guide to Tomographic Reconstruction and Talbot Imaging},
  doi       = {10.25972/OPUS-28143},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-281437},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {X-ray dark-field imaging allows to resolve the conflict between the demand for centimeter scaled fields of view and the spatial resolution required for the characterization of fibrous materials structured on the micrometer scale. It draws on the ability of X-ray Talbot interferometers to provide full field images of a sample's ultra small angle scattering properties, bridging a gap of multiple orders of magnitude between the imaging resolution and the contrasted structure scale. The correspondence between shape anisotropy and oriented scattering thereby allows to infer orientations within a sample's microstructure below the imaging resolution. First demonstrations have shown the general feasibility of doing so in a tomographic fashion, based on various heuristic signal models and reconstruction approaches. Here, both a verified model of the signal anisotropy and a reconstruction technique practicable for general imaging geometries and large tensor valued volumes is developed based on in-depth reviews of dark-field imaging and tomographic reconstruction techniques. To this end, a wide interdisciplinary field of imaging and reconstruction methodologies is revisited. To begin with, a novel introduction to the mathematical description of perspective projections provides essential insights into the relations between the tangible real space properties of cone beam imaging geometries and their technically relevant description in terms of homogeneous coordinates and projection matrices. Based on these fundamentals, a novel auto-calibration approach is developed, facilitating the practical determination of perspective imaging geometries with minimal experimental constraints. A corresponding generalized formulation of the widely employed Feldkamp algorithm is given, allowing fast and flexible volume reconstructions from arbitrary tomographic imaging geometries. Iterative reconstruction techniques are likewise introduced for general projection geometries, with a particular focus on the efficient evaluation of the forward problem associated with tomographic imaging. A highly performant 3D generalization of Joseph's classic linearly interpolating ray casting algorithm is developed to this end and compared to typical alternatives. With regard to the anisotropic imaging modality required for tensor tomography, X-ray dark-field contrast is extensively reviewed. Previous literature is brought into a joint context and nomenclature and supplemented by original work completing a consistent picture of the theory of dark-field origination. Key results are explicitly validated by experimental data with a special focus on tomography as well as the properties of anisotropic fibrous scatterers. In order to address the pronounced susceptibility of interferometric images to subtle mechanical imprecisions, an efficient optimization based evaluation strategy for the raw data provided by Talbot interferometers is developed. Finally, the fitness of linear tensor models with respect to the derived anisotropy properties of dark-field contrast is evaluated, and an iterative scheme for the reconstruction of tensor valued volumes from projection images is proposed. The derived methods are efficiently implemented and applied to fiber reinforced plastic samples, imaged at the ID19 imaging beamline of the European Synchrotron Radiation Facility. The results represent unprecedented demonstrations of X-ray dark-field tensor tomography at a field of view of 3-4cm, revealing local fiber orientations of both complex shaped and low-contrast samples at a spatial resolution of 0.1mm in 3D. The results are confirmed by an independent micro CT based fiber analysis.},
  subject      = {Dreidimensionale Rekonstruktion},
  language  = {en}
}
@phdthesis{Heck2005,
  author    = {Heck, Klaus},
  title     = {Wireless LAN performance studies in the context of 4G networks},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-14896},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2005},
  abstract  = {Wireless communication is nothing new. The first data transmissions based on electromagnetic waves have been successfully performed at the end of the 19th century. However, it took almost another century until the technology was ripe for mass market. The first mobile communication systems based on the transmission of digital data were introduced in the late 1980s. Within just a couple of years they have caused a revolution in the way people communicate. The number of cellular phones started to outnumber the fixed telephone lines in many countries and is still rising. New technologies in 3G systems, such as UMTS, allow higher data rates and support various kinds of multimedia services. Nevertheless, the end of the road in wireless communication is far from being reached. In the near future, the Internet and cellular phone systems are expected to be integrated to a new form of wireless system. Bandwidth requirements for a rich set of wireless services, e.g.\ video telephony, video streaming, online gaming, will be easily met. The transmission of voice data will just be another IP based service. On the other hand, building such a system is by far not an easy task. The problems in the development of the UMTS system showed the high complexity of wireless systems with support for bandwidth-hungry, IP-based services. But the technological challenges are just one difficulty. Telecommunication systems are planned on a world-wide basis, such that standard bodies, governments, institutions, hardware vendors, and service providers have to find agreements and compromises on a number of different topics. In this work, we provide the reader with a discussion of many of the topics involved in the planning of a Wireless LAN system that is capable of being integrated into the 4th generation mobile networks (4G) that is being discussed nowadays. Therefore, it has to be able to cope with interactive voice and video traffic while still offering high data rates for best effort traffic. Let us assume a scenario where a huge office complex is completely covered with Wireless LAN access points. Different antenna systems are applied in order to reduce the number of access points that are needed on the one hand, while optimizing the coverage on the other. No additional infrastructure is implemented. Our goal is to evaluate whether the Wireless LAN technology is capable of dealing with the various demands of such a scenario. First, each single access point has to be capable of supporting best-effort and Quality of Service (QoS) demanding applications simultaneously. The IT infrastructure in our scenario consists solely of Wireless LAN, such that it has to allow users surfing the Web, while others are involved in voice calls or video conferences. Then, there is the problem of overlapping cells. Users attached to one access point produce interference for others. However, the QoS support has to be maintained, which is not an easy task. Finally, there are nomadic users, which roam from one Wireless LAN cell to another even during a voice call. There are mechanisms in the standard that allow for mobility, but their capabilities for QoS support are yet to be studied. This shows the large number of unresolved issues when it comes to Wireless LAN in the context of 4G networks. In this work we want to tackle some of the problems.},
  subject      = {Drahtloses lokales Netz},
  language  = {en}
}
@phdthesis{Saal2017,
  author    = {Saal, Lena},
  title     = {Whole transcriptome profiling of compartmentalized motoneurons},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-140006},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {Spinal muscular atrophy and amyotrophic lateral sclerosis are the two most common devastating motoneuron diseases. The mechanisms leading to motoneuron degeneration are not resolved so far, although different hypotheses have been built on existing data. One possible mechanism is disturbed axonal transport of RNAs in the affected motoneurons. The underlying question of this study was therefore to characterize changes in transcript levels of distinct RNAs in cell culture models of spinal muscular atrophy and amyotrophic lateral sclerosis, especially in the axonal compartment of primary motoneurons. To investigate this in detail we first established compartmentalized cultures of Primary mouse motoneurons. Subsequently, total RNA of both compartments was extracted separately and either linearly amplified and subjected to microarray profiling or whole transcriptome amplification followed by RNA-Sequencing was performed. To make the whole transcriptome amplification method suitable for compartmentalized cultures, we adapted a double-random priming strategy. First, we applied this method for initial optimization onto serial dilutions of spinal cord RNA and later on to the compartmentalized motoneurons. Analysis of the data obtained from wildtype cultures already revealed interesting results. First, the RNA composition of axons turned out to be highly similar to the somatodendritic compartment. Second, axons seem to be particularly enriched for transcripts related to protein synthesis and energy production. In a next step we repeated the experiments by using knockdown cultures. The proteins depleted hereby are Smn, Tdp-43 and hnRNP R. Another experiment was performed by knocking down the non-coding RNA 7SK, the main interacting RNA of hnRNP R. Depletion of Smn led to a vast number of deregulated transcripts in the axonal and somatodendritic compartment. Transcripts downregulated in the axons upon Smn depletion were especially enriched for GOterms related to RNA processing and encode proteins located in neuron projections including axons and growth cones. Strinkingly, among the upregulated transcripts in the somatodendritic compartment we mainly found MHC class I transcripts suggesting a potential neuroprotective role. In contrast, although knockdown of Tdp-43 also revealed a large number of downregulated transcripts in the axonal compartment, these transcripts were mainly associated with functions in transcriptional regulation and RNA splicing. For the hnRNP R knockdown our results were again different. Here, we observed downregulated transcripts in the axonal compartment mainly associated with regulation of synaptic transmission and nerve impulses. Interestingly, a comparison between deregulated transcripts in the axonal compartment of both hnRNP R and 7SK knockdown presented a significant overlap of several transcripts suggesting some common mechanism for both knockdowns. Thus, our data indicate that a loss of disease-associated proteins involved in axonal RNA transport causes distinct transcriptome alterations in motor axons.},
  subject      = {Axon},
  language  = {en}
}
@phdthesis{Roemer2014,
  author    = {R{\"o}mer, Daniela},
  title     = {Where and how to build? Influence of social and environmental cues on nest building behavior in leaf-cutting ants},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-109409},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2014},
  abstract  = {This thesis explores the influence of social and environmental cues on the nest building behavior of leaf-cutting ants. Especially, the investigations are aimed at evaluating the mechanisms of nest building and how the nest environment can spatially guide building responses that lead to an adaptive nest architecture. The emergence of nest chambers in the nest of the leaf-cutting ant Acromyrmex lundi were evaluated. Rather than excavating nest chambers in advance, at places where workers encounter suitable environmental conditions for brood and fungus rearing, these items have to be present at a site. When presented in the laboratory with a choice between two otherwise identical digging sites, offering suitable environmental conditions, but one containing brood, the workers displayed a higher excavation activity at the site where they encountered the putative content of a chamber. The shape of the excavated cavity was also more round and chamber-like. It is concluded that leaf-cutting ants respond to social cues during nest building. Excavation is a costly process and colonies have to spend a part of their energy stores on nest building, so that regulatory responses for the control of nest excavation are expected to occur. Worker density at the beginning of the digging process influenced digging activity while the presence of in-nest stores did not. Stored brood and fungus did however influence the architecture of the excavated nest, leading to the excavation of larger chambers and smaller tunnels. While self-organized mechanisms appear to be involved in the nest building process, the social cues of the ants' environment during building clearly influence the nest architecture and lead to an adjustment of the nest size to the current space needs of the colony. Workers secondarily regulated nest size by the opportunistic refilling of unused space with excavated soil pellets. As the ants should provide suitable conditions for brood and fungus rearing, they should show a behavioral response to CO2 concentrations, as the gas is known to hinder fungus respiration. Workers of A. lundi did indeed avoid high CO2-levels for fungus rearing but actually preferred CO2-values in the range encountered close to the soil surface, where this species excavates their nests. However, different CO2-levels did not affect their excavation behavior. While fungus chambers make up part of a leaf-cutting ant nest, most leaf-cutting ants of the genus Atta also spent part of the colony's energy on excavating large, voluminous chambers for waste disposal, rather than scattering the material aboveground. It is expected that leaf-cutting ants also show environmental preferences for waste management. In experiments Atta laevigata workers preferred deposition in a warm and dry environment and showed no preference for specific CO2-levels. The continued accumulation of waste particles in a waste chamber seems to be based on the use of volatiles. These originate from the waste itself, and seem to be used as an orientation cue by workers relocating the material. The ensuing large accumulation of waste at one site should result in the emergence of more voluminous chambers for waste disposal.},
  subject      = {Nestbau},
  language  = {en}
}
@phdthesis{Karch2002,
  author    = {Karch, Oliver},
  title     = {Where am I? - Indoor localization based on range measurements},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-8442},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2002},
  abstract  = {Nowadays, robotics plays an important role in increasing fields of application. There exist many environments or situations where mobile robots instead of human beings are used, since the tasks are too hazardous, uncomfortable, repetitive, or costly for humans to perform. The autonomy and the mobility of the robot are often essential for a good solution of these problems. Thus, such a robot should at least be able to answer the question "Where am I?". This thesis investigates the problem of self-localizing a robot in an indoor environment using range measurements. That is, a robot equipped with a range sensor wakes up inside a building and has to determine its position using only its sensor data and a map of its environment. We examine this problem from an idealizing point of view (reducing it into a pure geometric one) and further investigate a method of Guibas, Motwani, and Raghavan from the field of computational geometry to solving it. Here, so-called visibility skeletons, which can be seen as coarsened representations of visibility polygons, play a decisive role. In the major part of this thesis we analyze the structures and the occurring complexities in the framework of this scheme. It turns out that the main source of complication are so-called overlapping embeddings of skeletons into the map polygon, for which we derive some restrictive visibility constraints. Based on these results we are able to improve one of the occurring complexity bounds in the sense that we can formulate it with respect to the number of reflex vertices instead of the total number of map vertices. This also affects the worst-case bound on the preprocessing complexity of the method. The second part of this thesis compares the previous idealizing assumptions with the properties of real-world environments and discusses the occurring problems. In order to circumvent these problems, we use the concept of distance functions, which model the resemblance between the sensor data and the map, and appropriately adapt the above method to the needs of realistic scenarios. In particular, we introduce a distance function, namely the polar coordinate metric, which seems to be well suited to the localization problem. Finally, we present the RoLoPro software where most of the discussed algorithms are implemented (including the polar coordinate metric).},
  subject      = {Autonomer Roboter},
  language  = {en}
}