@phdthesis{Seider2004,
  author    = {Seider, David},
  title     = {Solving an eigenvalue problem in laser simulation},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-10057},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {In this thesis a new and powerful approach for modeling laser cavity eigenmodes is presented. This approach is based on an eigenvalue problem for singularly perturbed partial differential operators with complex coefficients; such operators have not been investigated in detail until now. The eigenvalue problem is discretized by finite elements, and convergence of the approximate solution is proved by using an abstract convergence theory also developed in this dissertation. This theory for the convergence of an approximate solution of a (quadratic) eigenvalue problem, which particularly can be applied to a finite element discretization, is interesting on its own, since the ideas can conceivably be used to handle equations with a more complex nonlinearity. The discretized eigenvalue problem essentially is solved by preconditioned GMRES, where the preconditioner is constructed according to the underlying physics of the problem. The power and correctness of the new approach for computing laser cavity eigenmodes is clearly demonstrated by successfully simulating a variety of different cavity configurations. The thesis is organized as follows: Chapter 1 contains a short overview on solving the so-called Helmholtz equation with the help of finite elements. The main part of Chapter 2 is dedicated to the analysis of a one-dimensional model problem containing the main idea of a new model for laser cavity eigenmodes which is derived in detail in Chapter 3. Chapter 4 comprises a convergence theory for the approximate solution of quadratic eigenvalue problems. In Chapter 5, a stabilized finite element discretization of the new model is described and its convergence is proved by applying the theory of Chapter 4. Chapter 6 contains computational aspects of solving the resulting system of equations and, finally, Chapter 7 presents numerical results for various configurations, demonstrating the practical relevance of our new approach.},
  subject      = {Laser},
  language  = {en}
}
@phdthesis{Erdmann2004,
  author    = {Erdmann, Marco},
  title     = {Coupled electron and nuclear dynamics in model systems},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9968},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {Subject of this work was to investigate the influence of nonadiabatic coupling on the dynamical changes of electron and nuclear density. The properties of electron density have neither been discussed in the stationary case, nor for excited electronic states or for a coupled electronic and nuclear motion. In order to remove these restrictions one must describe the quantum mechanical motion of all particles in a system at the same level. This is only possible for very small systems. A model system developed by Shin and Metiu [1, 2] contains all necessary physical ingredients to describe a combined electronic and nuclear motion. It consists of a single nuclear and electronic degree of freedom and the particle interaction is parameterized in such a way as to allow for a facile switching between and adiabatic (Born-Oppenheimer type) and a strongly coupled dynamics. The first part of the work determined the "static" properties of the model system: The calculation of electronic eigenfunctions, adiabatic potential curves, kinetic coupling elements and transition dipole moments allowed for a prediction of the coupled dynamics. The potentials obtained from different parameterization showed two distinct cases: In the first case the ground and first excited state are separated by a large energy gap which is the typical Born-Oppenheimer case; the second one exhibits an avoided crossing which results in a breakdown of the adiabatic approximation. Due to the electronic properties of the system, the quantum dynamics in the two distinct situations is very different. This was illustrated by calculating nuclear and electron densities as a function of time. In the Born-Oppenheimer case, the electron density followed the vibrational motion of the nucleus. This was demonstrated in two examples. In the strongly coupled case the wave packet did not exhibit features caused by nonadiabatic coupling. However, projections of the wave function onto the electronic states revealed the usual picture obtained from solutions of the nuclear Schr{\"o}dinger equation involving coupled electronic states. In that case the nuclear motion triggered charge transfer via nonadiabatic coupling. The second part of the work demonstrated that the model system can easily be modified to yield binding situations often found in diatomic molecules. The different situations can be characterized in terms of bound and dissociative adiabatic potential curves. The investigation focussed on the case of an electronic predissociation, where the ground state is dissociative in the asymptotic limit of large internuclear distances. Within our model system we were able to demonstrate how the character of the electron density changes during the fragmentation process. In the third part we investigated the influence of external fields on the correlated dynamics of electron and nucleus. Employing adiabatic potential curves, the structure of absorption spectra can be understood within the weak-field limit. In the above described Born-Oppenheimer case the adiabatically calculated spectrum was in very good agreement with the exact one, whereas in the strongly coupled case the obtained spectrum was not able to resemble the exact one. Regarding the dynamics during a laser excitation process the time-dependent electron and nuclear densities nicely illustrated the famous Franck-Condon principle. The interaction with strong laser pulses lead to an excitation of many bound electronic and vibrational states. The electron density reflected the classical-like quiver motion of the electron induced by the fast variations of the electric field. The nucleus did not follow these fast oscillations because of its much larger mass. The last part of the work extended the original model system by including an additional electron. As a consequence of the Pauli principle, the spatial electronic wave function has to be either symmetric or anti-symmetric with respect to exchange of the two electrons. This corresponds to anti-parallel or parallel electron spins, respectively. The extended model already contains the physical properties of a many-electron system. Solving the time-dependent Schr{\"o}dinger equation for a typical vibrational wave packet motion clearly indicated that the electron density is no longer suited to "localize" single electrons. We extended the definition of the electron localization function (ELF) to an exact, time-dependent wave function and demonstrated, how the ELF can be used to further characterize a coupled electron and nuclear motion. Finally, we gave an outlook of how to define electron localization in the case of anti-parallel electron spins. We derived a quantity similar to the ELF denoted "anti-parallel spin electron localization function" (ALF) and demonstrated that the ALF allows to follow time-dependent changes of the electron localization in a numerical example. [1] S. Shin, H. Metiu, J. Chem. Phys. 1995, 102, 9285. [2] S. Shin, H. Metiu, J. Phys. Chem. 1996, 100, 7867.},
  subject      = {Nichtadiabatischer Prozess},
  language  = {en}
}
@phdthesis{Menth2004,
  author    = {Menth, Michael},
  title     = {Efficient admission control and routing for resilient communication networks},
  doi       = {10.25972/OPUS-846},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9949},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {This work is subdivided into two main areas: resilient admission control and resilient routing. The work gives an overview of the state of the art of quality of service mechanisms in communication networks and proposes a categorization of admission control (AC) methods. These approaches are investigated regarding performance, more precisely, regarding the potential resource utilization by dimensioning the capacity for a network with a given topology, traffic matrix, and a required flow blocking probability. In case of a failure, the affected traffic is rerouted over backup paths which increases the traffic rate on the respective links. To guarantee the effectiveness of admission control also in failure scenarios, the increased traffic rate must be taken into account for capacity dimensioning and leads to resilient AC. Capacity dimensioning is not feasible for existing networks with already given link capacities. For the application of resilient NAC in this case, the size of distributed AC budgets must be adapted according to the traffic matrix in such a way that the maximum blocking probability for all flows is minimized and that the capacity of all links is not exceeded by the admissible traffic rate in any failure scenario. Several algorithms for the solution of that problem are presented and compared regarding their efficiency and fairness. A prototype for resilient AC was implemented in the laboratories of Siemens AG in Munich within the scope of the project KING. Resilience requires additional capacity on the backup paths for failure scenarios. The amount of this backup capacity depends on the routing and can be minimized by routing optimization. New protection switching mechanisms are presented that deviate the traffic quickly around outage locations. They are simple and can be implemented, e.g, by MPLS technology. The Self-Protecting Multi-Path (SPM) is a multi-path consisting of disjoint partial paths. The traffic is distributed over all faultless partial paths according to an optimized load balancing function both in the working case and in failure scenarios. Performance studies show that the network topology and the traffic matrix also influence the amount of required backup capacity significantly. The example of the COST-239 network illustrates that conventional shortest path routing may need 50\% more capacity than the optimized SPM if all single link and node failures are protected.},
  subject      = {Kommunikation},
  language  = {en}
}
@phdthesis{Pyz2004,
  author    = {Pyz, Elwira},
  title     = {Identification of rat NKT cells and molecular analysis of their surface receptor mediated activation},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9767},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {Zusammenfassung NKT Zellen wurden urspr{\"u}nglich {\"u}ber die gleichzeitige Expresion eines T-Zellantigenrezeptors (TZR) und den NK-Zellmarkern NKRP1A im Menschen bzw. NK1.1. (NKRP1C) in der Maus definiert. In Mensch und Maus exprimieren die meisten NKT Zellen CD1d restringierte TZR mit charakteristischen Genumlagerungen- Va24JaQ/Vb11 im Menschen und Va14Ja18/Vb8.2 in der Maus. Den NKT Zellen werden außerdem wichtige Funktionen in der „first line defence" und der Immunregulation zugesprochen. Gegenstand der Doktorarbeit war die Charakterisierung eines hypothetischen Gegenst{\"u}ckes in der Ratte. In der Maus wurden rund 30\% der intrahepatischen Lymphozyten (IHL) und 3\% der Milzlymphozyten als CD1d restringierte NK T Zellen identifiziert und konnten mittels a-GalCer beladenen Maus-CD1d Tetramer visualisiert werden. Wie in der Maus wurden in der Ratte NKRP1A+TZR+ Zellen vorwiegend in der Leber gefunden, waren aber f{\"u}nfmal weniger h{\"a}ufig. F344 Ratten NKT Zellen waren dar{\"u}ber hinaus im Gegensatz zu den CD4+ oder CD4-CD8- Maus NKT Zellen meistens CD8 positiv und banden kein mCD1d Tetramer. Da in der menschlichen Leber CD1d-restringierte Va24JQ+ T Zellen ebenfalls viel seltener als in der Maus sind, scheint es nun m{\"o}glich, daß der Ph{\"a}notyp der Ratten NKT Zellen eher dem des Menschen als dem der Maus entspricht. Ein Test der F{\"a}higkeit von F344 Leber- und Milzlymphozyten nach Kultur mit a-GalCer Cytokine zu produzieren, ergab {\"a}hnlich wie in der Maus eine Produktion von IL-4 und IFN-g;. Aus diesem Grund kann eine fehlende Reaktivit{\"a}t von Ratten NKT Zellen f{\"u}r a-GalCer nicht der Grund f{\"u}r eine fehlende mCD1d Tetramerbindung sein. Um die Reaktivit{\"a}t der NKRP1A+TZR+ Rattenzellen auf a-GalCer besser zu verstehen, wurde der Ratten TZR analysiert. RT-PCR von Leberlymphozyten mit Va14-spezifischen Primern und die Analyse der klonierten PCR Produkte ergab ein viel schw{\"a}cheres Signal f{\"u}r Ratten als f{\"u}r Maus cDNA. Dar{\"u}ber hinaus zeigten Sequenzanalysen, daß das Va14 auch mit anderen J als dem f{\"u}r TCRinv typischem Ja18 rearrangiert war. Die niedrige Anzahl von Va14Ja18 „in frame" Umlagerungen legt Nahe, daß nur ein kleiner Anteil der Leber-lymphozyten CD1d restringierte NKT Zellen sind. Maus und humane NKT Zellen erkennen durch CD1d-b2m Komplexe pr{\"a}sentiertes a-GalCer und reagieren mit Aktivierung, Proliferation und Cytokinproduktion. Um die F{\"a}higkeit von Maus und Ratten-CD1d a-GalCer zu pr{\"a}sentieren, zu testen, wurde das CD1d Molek{\"u}l der Ratte kloniert. Sequenzanlyse und funktionelle Tests best{\"a}tigten die strukturelle und funktionelle Homologie des CD1d beider Spezies. Gleichzeitig wurde zur Analyse der Reaktivit{\"a}t von NKRP1A+TZR+ Zellen auf a-GalCer ein Ratten Va14+ invarianter TZR kloniert und in einem TZR- T-Zellhybridom (BWr/mCD28) exprimiert. Zellen die transgenen Ratten Va14+TZR und CD28 exprimierten, sezernierten IL-2 nach Stimulation mit aTZR/CD3 Antik{\"o}rper aber zeigten keine Spezifit{\"a}t f{\"u}r a-GalCer. Die fehlende Reaktivit{\"a}t f{\"u}r a-GalCer und die fehlende Bindung von mCD1-a-GalCer Tetramer waren wahrscheinlich durch Aminos{\"a}uresubstitionen insbesondere an Position 71 (51 nach IMGT Nomenklatur) der klonierten TZRa Kette begr{\"u}ndet. Eine „Umkehrung" dieser {\"A}nderung wurde mittels molekularbiologischer Techniken durchgef{\"u}hrt aber Expression dieses TZR auf BWr/mCD28 wurde nicht erreicht. Im Gegensatz zum invarianten Va14+ Ratten TZR war der Maus Va14+ TZR voll funktional und spezifisch f{\"u}r mCD1d Tetramer. KT12 Hybridom und Maus TZRinv exprimierende BWr/mCD28 Zellen wurden sowohl durch Ratten als durch Maus CD1d pr{\"a}sentiertes a-GalCer aktiviert. Dasselbe galt f{\"u}r TZR, die eine Maus Va14 TZR Kette und eine Ratten Vb8.4 TZR Kette enthielten. Im Gegensatz hierzu antworteten Linien mit mVa14 und Ratten Vb8.2 nur auf durch Ratten und nicht auf durch Maus CD1d pr{\"a}sentiertes a-GalCer und banden nahezu kein mCD1d Tetramer. Dies legt Nahe, daß Keimbahn kodierte der b-Kettenbereiche (CDR2 oder CDR4) speziesspezifische Bereiche des CD1d erkennen. Weiterhin wurde gefunden, das die Zytokinsekretion der Zellinien durch CD80 spezifische monoklonale Antik{\"o}rper inhibiert wurde, was eine wichtige Rolle der CD80-CD28 Interaktion bei der Aktivierung dieser Zellen nahelegt. Um zu sehen ob NKT Zellen auch in anderen Rattenst{\"a}mmen als F344 existieren, wurde H{\"a}ufigkeit und Funktion von NKRP1A+TZR+ Zellen in F344 und LEW Ratten miteinander verglichen. F344 und LEW, zwei Rattenst{\"a}mme die unterschiedliche CD1d Allele tragen, zeigten in der Analyse mit einem neu generierten rCD1d spezifischen monoklonalen Antik{\"o}rper nur geringe Unterschiede in der Expressionsst{\"a}rke. Hingegen, unterschieden sich beide St{\"a}mme in der Reaktivit{\"a}t f{\"u}r a-GalCer. NKRP1A+ Zellen waren in der LEW Ratte weniger h{\"a}ufig als in der F344 Ratte und antworteten in vitro nicht auf a-GalCer oder sein Analogon OCH. Ein Resultat, das insbesodere angesichts der besonderen Empf{\"a}nglichkeit von LEW Ratten f{\"u}r experimentell induzierte organspezifische Autoimmunerkrankungen von besonderem Interesse ist. Zusammgefasst kann gesagt werden, daß das Maus und Ratten CD1d/TZRinv NKT Zellsystem hohe strukturelle und funktionale Homologie aufweist, aber daß es wie im Menschen weniger invariante NKT Zellen in der Ratte als in der Maus gibt. TZR transgene Zelllinien wiesen ein speziesspezifisches Muster in der a-GalCer Erkennung auf, das f{\"u}r die Analyse von CDd/TZR-Kontaktbereichen von großem Nutzen sein wird. Dasselbe gilt f{\"u}r den Ratten und Maus-CD1d-spezifischen monoklonalen Antik{\"o}rper, der im Rahmen der Studie generiert wurde. Dieser kann bei der Charakterisierung der CD1d Proteinexpression in verschiedenen Geweben und der besseren funktionellen Charakterisierung von CD1d restringierten T Zellen der Ratte eingesetzt werden.},
  subject      = {Ratte},
  language  = {en}
}
@phdthesis{Ye2004,
  author    = {Ye, Fang},
  title     = {The role of DNA supercoiling in the coordinated regulation of gene expression in Helicobacter pylori},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9878},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {Summary Mechanisms of global gene regulation in bacteria are not well characterized yet. Changes in global or local supercoiling of chromosomal DNA are thought to play a role in global gene silencing and gene activation. In Helicobacter pylori, a bacterium with few dedicated transcriptional regulators, the structure of some promoters indicates a dependency on DNA topology. For example, the promoter of the major flagellar subunit gene flaA ({\´o}28-dependent) has a shorter spacing of 13 nucleotides (nt) in comparison to the consensus promoter (15 nt). Supercoiling changes might be a mechanism of gene-specific and global transcriptional regulation in this bacterium. The aim of this study was to elucidate, if changes in global supercoiling have an influence on global gene regulation in H. pylori, and on the temporal regulation of the flagellar biosynthesis pathway in this organism. In the present work, global DNA supercoiling in H. pylori was visualized for the first time, by determining the supercoiling state of plasmids under different growth conditions. Using this method, we showed that cellular supercoiling was clearly growth phase-dependent in H. pylori. Coinciding with increased supercoiling during the growth phases, transcription of the flaA gene was increased, while the transcription of a second {\´o}28-dependent gene with regular promoter spacing (HP0472) was reduced, supporting the hypothesis that growth phase-dependency of promoters might be mediated by changes of DNA topology. Supercoiling in H. pylori could be influenced in a reproducible fashion by inhibition of gyrase using novobiocin, which led to DNA relaxation and to a concomitant decrease of flaA transcript levels. Promoter spacer mutagenesis of the flaA promoter was performed. With flaA promoters of increased or reduced length, transcription of flaA was reduced, less susceptible to supercoiling changes, and, under specific conditions, inverted as compared to the wild type promoter. Transcriptional interdependence between the coupled topA-flaB genes and flaA was found by analysis of the flaA promoter mutants. Chromosomally linked gyrA-flgR, and topA-flaB genes were all dependent on supercoiling and coregulated with each other. Comprehensive transcript profiling (DNA microarrays) of wildtype H. pylori with and without novobiocin treatment identified a number of genes (10\% of total genes), including flagellin, virulence and housekeeping genes, which were strongly dependent on and appeared to be synchronized by supercoiling changes (transcriptional up- or downregulation). These findings indicate a tightly coupled temporal regulation of flagellar biogenesis and metabolism in H. pylori, dependent on global supercoiling. A specific group of genes was also regulated in H. pylori by overexpression of Topoisomerase I, as detected by genome-wide analysis (DNA microarray). The DNA-bending protein HU is thought to be responsible for influencing the negative supercoiling of DNA, through its ability to wrap DNA. HU is encoded by the hup single gene in H. pylori, and constitutively expressed during the whole growth curve. An H. pylori hup mutant was constructed. H. pylori cells lacking HU protein were viable, but exhibited a severe growth defect. Our data indicate that the lack of HU dramatically changes global DNA supercoiling, indicating an important function of HU in chromosome structuring in H. pylori. Transcriptome analyses were performed and demonstrated that a total of 66 genes were differentially transcribed upon hup deletion, which include virulence genes and many other cell functions. The data indicate that HU might act as further important global regulator in H. pylori. Increased gene expression of heat shock proteins and a decreased transcription of the urease gene cluster may indicate a co-ordinated response of H. pylori to changes of environmental conditions in its specific ecological niche, mediated by HU. After the whole genomic sequences of H. pylori strains 26695 and J99 were published, two ORFs (HP0116 and HP0440) were presumptively annotated as topoisomerase I orthologs. HP0116 is the functional H. pylori topoisomerase I (TopA). HP0440 (topA2) was found in only few (5 of 43) strains. Western blot analysis indicated that TopA2 is antigenically different from TopA. TopA2 is transcribed in H. pylori, but the protein must be functionally different from TopA, since it is lacking one functionally essential zinc finger motif, and was not able to functionally complement a TopA-deficient E. coli. Like topA, topA2 was also transcribed in a growth phase-dependent manner. We did not find a function of TopA2 in DNA structuring or topology, but, in the present study, we were able for the first time to establish a unique function for TopA2 in global gene regulation, by comprehensive transcriptome analysis (DNA microarray). Transcriptome analysis showed that a total of 46 genes were differentially regulated upon topA2 deletion, which included flagellar genes and urease genes. These results suggest that TopA2 might act as a novel important regulator of both flagellar biosynthesis and urease in H. pylori.},
  subject      = {Helicobacter pylori},
  language  = {en}
}
@phdthesis{Jiang2004,
  author    = {Jiang, Fan},
  title     = {Water, mineral nutrient and hormone flows and exchanges in the hemiparasitic association between root hemiparasite Rhinanthus minor and the host Hordeum vulgare},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9863},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {Summary Using the facultative root hemiparasite Rhinanthus minor and Hordeum vulgare as a host, several aspects of water relations, the flows and partitioning of mineral nutrients, the flows, depositions and metabolism of abscisic acid (ABA) and zeatin type cytokinins (zeatin Z, zeatin riboside ZR, zeatin nucleotide ZN) within the host, the parasite and between host and parasite and the flows and partitioning of the transport metabolites mannitol in the parasite, and of sucrose in the host, have been studied during the study period 41 to 54 days after planting, i.e about 30 to 43 days after successful attachment of the parasite to the host. Water relations Extraction of xylem sap by the parasite from the host's roots is facilitated by considerably higher transpiration per leaf area in the parasite than in the host and by the fact that stomata of attached Rhinanthus were wide open all day and night despite extremely high ABA concentrations in the leaves. By comparison, another related root hemiparasite, Melampyrum arvense, parasitising on various grasses in the field (botanic garden), showed normal diurnal stomatal behaviour. The abnormal behaviour of Rhinanthus stomata was not due to anatomical reasons as closure could be induced by applying high external ABA concentrations. Remarkable differences have been detected between the hydraulic conductance of barley seminal roots showing relatively low values, and that of Rhinanthus the seminal root showing very high values. The latter could be related to the observed high ABA concentrations in these roots. Whole plant water uptake, transpirational losses, growth-dependent deposition and the flows of water within the plants have been measured in singly growing Rhinanthus and Hordeum plants and in the parasitic association between the two. Water uptake, deposition and transpiration in Rhinanthus were dramatically increased after attachment to the barley host; most of the water used by the parasite was extracted as xylem sap from the host, thereby scavenging 20\% of the total water taken up by the host's roots. This water uptake by the parasitised host, however, due to a parasite induced reduction in the hosts growth, was decreased by 22\% as compared to non- parasitised barley. The overall changes in growth-related water deposition in host and parasite pointed to decreased shoot and relatively favoured root growth in the host and to strongly favoured shoot growth and less strongly increased root growth only in the parasite. These changes in the host became more severe, when more than one Rhinanthus was parasitising one barley plant. Mineral nutrients relations 5 mM NO3- supply In parasitising Rhinanthus shoot growth was 12-fold, but root growth only twofold increased compared to the non-parasitising (very small) plants. On the other hand, in the Hordeum host, shoot dry matter growth was clearly reduced, by 33\% in leaf laminae and by 52\% in leaf sheaths, whereas root growth was only slightly reduced as a consequence of parasitism. Growth-dependent increments of total N and P and of K, Ca and Mg in parasitising Rhinanthus shoot were strongly increased, particularly increments of total N and P, which were 18 and 42 times, respectively, higher than in the small solitary Rhinanthus. On the other hand, increments of the above mineral nutrients in leaf sheaths of parasitised Hordeum vulgare were more strongly decreased than in leaf laminae in response to parasitic attack. Estimation of the flows of nutrients revealed that Rhinanthus withdrew from the host xylem sap about the same percentage of each nutrients: 18\% of total N, 22\% of P and 20\% of K. Within the host almost all net flows of nutrient ions were decreased due to parasitism, but retranslocation from shoot to root-as related to xylem flow-was somewhat increased for all nutrients. Quantitative information is provided to show that the substantially increased growth in the shoot of attached Rhinanthus and the observed decrease in Hordeum shoot growth after infection were related to strongly elevated supply of nitrogen and phosphorus in the parasite and to incipient deficiency of these nutrients in the parasitised host. The flows of nutrients between host and parasite are discussed in terms of low selectivity of nutrient abstraction from the host xylem by the hemiparasite Rhinanthus minor. 1 mM NO3- or 1 mM NH4+ supply Rhinanthus shoot growth as measured by dry matter increase, was 19-fold (1 mM NO3-) and 15-fold (1 mM NH4+), but root growth only twofold (1 mM NO3-) and 2.9-fold (1 mM NH4+) increased-relative to singly growing Rhinanthus-when parasitising on host barley. In the Hordeum host, shoot dry matter growth was clearly reduced, whereas root growth was only slightly affected. Growth-dependent increments of total N and P and of K, Ca and Mg in parasitising Rhinanthus shoot were strongly increased, particularly increments of total N or of P, which were 20 or 53 times (1 mM NO3-) and 18 or 51 times (1 mM NH4+) , respectively, higher than those in solitary Rhinanthus. Within the host almost all net flows of nutrient ions were decreased due to parasitism. Flows of mannitol in parasite and sucrose flows in host barley When the plants were supplied with 5 mM NO3-, the biosynthesis of mannitol in Rhinanthus shoots increased 16-fold by parasitism, resulting in a 15-fold higher mannitol flow in the phloem and a 10-fold higher deposition in the shoot. Also the backward transport of mannitol in the xylem were increased 10-fold after attachment. Lower level nitrogen supply increased the deposition of mannitol in both single and attached Rhinanthus shoot and root. No mannitol was found in barley roots even in the direct vicinity of the haustoria. This indicates there are no backward transport of xylem sap from parasite to host. Compared to unparasitised barley, the net biosynthesis and deposition of sucrose in the shoot and the phloem flow was decreased substantially when plants were supplied with 5 mM NO3- or 1 mM NO3-. No sucrose has been detected in barley xylem sap and consequently there was no indication of a sucrose transfer from the host to the parasite. A possible involvement of mannitol in the abscisic acid relations of the parasite is discussed. ABA relations When the plants were supplied with 5 mM NO3-, there were weak or no effects of parasitism on ABA flows, biosynthesis and ABA degradation in barley. However, ABA growth-dependent deposition was significantly increased in the leaf laminae (3 fold) and in leaf sheath (2.4 fold), but not in roots. Dramatic changes in ABA flows, metabolism and deposition on a per plant basis, however, have been observed in Rhinanthus. Biosynthesis in the roots was 12-fold higher after attachment resulting in 14-fold higher ABA flows in the xylem. A large portion of this ABA was metabolised, a small portion was deposited. Phloem flows of ABA were increased 13-fold after attachment. The concentrations of ABA in tissues and xylem sap were higher in attached Rhinanthus by an order of magnitude than in host tissues and xylem sap. Similar dramatic difference existed when comparing the high concentrations in the xylem sap of single Rhinanthus with unparasitised barley. As compared to 5 mM NO3-, lower NO3- or 1 mM NH4+ supply doubled the ABA concentrations in barley leaf laminae, while having only small or no significant effects in the other organs. The possible special functions of ABA for the parasite are discussed. Zeatin type cytokinins relations Parasitism decreased, in the case of zeatin (Z), the synthesis (by 57\%) in the root, xylem flows (by 56\%) and metabolism (by 71\%) in leaf laminae, however, increased the phloem flows of zeatin massively (3-fold) in host barley. The deposition of zeatin in the root of Rhinanthus and the flowing in xylem and phloem were 24, 12, 29-fold, respectively, increased after successfully attaching to the host barley. However, net biosynthesis of zeatin in Rhinanthus roots decreased by 39\% after attachment. This indicates that a large portion (70\%) of xylem flow of zeatin in attached Rhinanthus was extracted from the host. In singly growing Rhinanthus plants, the balance of zeatin deposition in the shoot was negative, i.e. zeatin was metabolised and exported back to root in the phloem. The xylem flows of zeatin riboside (ZR) in barley decreased by 39\% after infected by Rhinanthus; phloem flow, which was 117\% relative to xylem flow was less decreased (by 13\%) after infection. Deposition of ZR has not been significantly affected in the leaf laminae, in leaf sheaths and roots. After parasitising on the host barley depositions in root, xylem flow and phloem flow increased 12, 18, 88-fold respectively in Rhinanthus. A large portion (57\%) of xylem flow of ZR in attached Rhinanthus was extracted from the host. In single Rhinanthus increament of shoot zeatin riboside was negative and a substantial portion was degraded in shoot and the rest was retranslocated back to the root in the phloem. A significant depositions of Z and ZR were detected in the haustoria of the Rhinanthus/barley association. Flows and deposition of zeatin nucleotides also have been investigated. The possible physiological functions of the large quantities of Z and ZR derived from the host barley, for the improved growth and the stomatal opening in the parasitising Rhinanthus are discussed.},
  subject      = {Hemiparasit},
  language  = {en}
}
@phdthesis{Pfeifer2004,
  author    = {Pfeifer, Thomas},
  title     = {Adaptive control of coherent soft X-rays},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9854},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {The availability of coherent soft x-rays through the nonlinear optical process of high-harmonic generation allows for the monitoring of the fastest events ever observed in the laboratory. The attosecond pulses produced are the fundamental tool for the time-resolved study of electron motion in atoms, molecules, clusters, liquids and solids in the future. However, in order to exploit the full potential of this new tool it is necessary to control the coherent soft x-ray spectra and to enhance the efficiency of conversion from laser light to the soft x-ray region in the harmonic-generation process. This work developed a comprehensive approach towards the optimization of the harmonic generation process. As this process represents a fundamental example of \emph{light}--\emph{matter} interaction there are two ways of controlling it: Shaping the generating laser \emph{light} and designing ideal states of \emph{matter} for the conversion medium. Either of these approaches was closely examined. In addition, going far beyond simply enhancing the conversion process it could be shown that the qualitative spectral response of the process can be modified by shaping the driving laser pulse. This opens the door to a completely new field of research: Optimal quantum control in the attosecond soft x-ray region---the realm of electron dynamics. In the same way as it is possible to control molecular or lattice vibrational dynamics with adaptively shaped femtosecond laser pulses these days, it will now be feasible to perform real-time manipulation of tightly bound electron motion with adaptively shaped attosecond light fields. The last part of this work demonstrated the capability of the herein developed technique of coherent soft-x-ray spectral shaping, where a measured experimental feedback was used to perform a closed-loop optimization of the interaction of shaped soft x-ray light with a sulfur hexafluoride molecule to arrive at different control objectives. For the optimization of the high-harmonic-generation process by engineering the conversion medium, both the gas phase and the liquid phase were explored both in experiment and theory. Molecular media were demonstrated to behave more efficiently than commonly used atomic targets when elliptically polarized driving laser pulses are applied. Theory predicted enhancement of harmonic generation for linearly polarized driving fields when the internuclear distance is increased. Reasons for this are identified as the increased overlap of the returning electron wavefunction due to molecular geometry and the control over the delocalization of the initial electronic state leading to less quantum-mechanical spreading of the electron wavepacket during continuum propagation. A new experimental scheme has been worked out, using the method of molecular wavepacket generation as a tool to enhance the harmonic conversion efficiency in `pump--drive' schemes. The latter was then experimentally implemented in the study of high-harmonic generation from water microdroplets. A transition between the dominant laser--soft-x-ray conversion mechanisms could be observed, identifying plasma-breakdown as the fundamental limit of high-density high-harmonic generation. Harmonics up to the 27th order were observed for optimally laser-prepared water droplets. To control the high-harmonic generation process by the application of shaped laser light fields a laser-pulse shaper based on a deformable membrane mirror was built. Pulse-shape optimization resulted in increased high-harmonic generation efficiency --- but more importantly the qualitative shape of the spectral response could be significantly modified for high-harmonic generation in waveguides. By adaptive optimization employing closed-loop strategies it was possible to selectively generate narrow (single harmonics) and broad bands of harmonic emission. Tunability could be demonstrated both for single harmonic orders and larger regions of several harmonics. Whereas any previous experiment reported to date always produced a plateau of equally intense harmonics, it has been possible to demonstrate ``untypical'' harmonic soft x-ray spectra exhibiting ``switched-off'' harmonic orders. The high degree of controllability paves the way for quantum control experiments in the soft x-ray spectral region. It was also demonstrated that the degree of control over the soft x-ray shape depends on the high-harmonic generation geometry. Experiments performed in the gas jet could not change the relative emission strengths of neighboring harmonic orders. In the waveguide geometry, the relative harmonic yield of neighboring orders could be modified at high contrast ratios. A simulation based solely on the single atom response could not reproduce the experimentally observed contrast ratios, pointing to the importance of propagation (phase matching) effects as a reason for the high degree of controllability observed in capillaries, answering long-standing debates in the field. A prototype experiment was presented demonstrating the versatility of the developed soft x-ray shaping technique for quantum control in this hitherto unexplored wavelength region. Shaped high-harmonic spectra were again used in an adaptive feedback loop experiment to control the gas-phase photodissociation reaction of SF\$_6\$ molecules. A time-of-flight mass spectrometer was used for the detection of the ionic fragments. The branching ratios of particular fragmentation channels could be varied by optimally shaped soft x-ray light fields. Although in one case only slight changes of the branching ratio were possible, an optimal solution was found, proving the sufficient technical stability of this unique coherent soft-x-ray shaping method for future applications in optimal control. Active shaping of the spectral amplitude in coherent spectral regions of \$\sim\$10~eV bandwidth was shown to directly correspond to shaping the temporal features of the emerging soft x-ray pulses on sub-femtosecond time scales. This can be understood by the dualism of frequency and time with the Fourier transformation acting as translator. A quantum-mechanical simulation was used to clarify the magnitude of temporal control over the shape of the attosecond pulses produced in the high-harmonic-generation process. In conjunction with the experimental results, the first attosecond time-scale pulse shaper could thus be demonstrated in this work. The availability of femtosecond pulse shapers opened the field of adaptive femtosecond quantum control. The milestone idea of closed-loop feedback control to be implemented experimentally was expressed by Judson and Rabitz in their seminal work titled ``Teaching lasers to control molecules''. This present work extends and turns around this statement. Two fundamentally new achievements can now be added, which are ``Teaching molecules to control laser light conversion'' and ``Teaching lasers to control coherent soft x-ray light''. The original idea thus enabled the leap from femtosecond control of molecular dynamics into the new field of attosecond control of electron motion to be explored in the future. The \emph{closed}-loop approach could really \emph{open} the door towards fascinating new perspectives in science. Coming back to the introduction in order to close the loop, let us reconsider the analogy to the general chemical reaction. Photonic reaction control was presented by designing and engineering effective media (catalysts) and controlling the preparation of educt photons within the shaped laser pulses to selectively produce desired photonic target states in the soft x-ray spectral region. These newly synthesized target states in turn could be shown to be effective in the control of chemical reactions. The next step to be accomplished will be the control of sub-femtosecond time-scale electronic reactions with adaptively controlled coherent soft x-ray photon bunches. To that end a time-of-flight high-energy photoelectron spectrometer has recently been built, which will now allow to directly monitor electronic dynamics in atomic, molecular or solid state systems. Fundamentally new insights and applications of the nonlinear interaction of shaped attosecond soft x-ray pulses with matter can be expected from these experiments.},
  subject      = {Ultrakurzer Lichtimpuls},
  language  = {en}
}
@phdthesis{Dem2003,
  author    = {Dem, Claudiu Dorin},
  title     = {Design and construction of a device for light scattering studies on airborne particles},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9605},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2003},
  abstract  = {This thesis is concerned with the development of an on-line in-situ device for a chemical characterisation of flowing aerosols. The thesis describes the principles and most important features of such a system, allowing also on-line measurements using Raman spectroscopy as a diagnostic technique An analysis of the effect of forced oscillations on the motion of the particle dispersed in a gas flow is given in Chapter 2. Also the most important particle parameters are introduced. A review of the particle/fluid interaction in laminar air flows and the response of the particle is presented. In Chapter 3 the behaviour of the particle under different external conditions (ion bombardment and electric fields) is extended. A brief review of the most important particle charging theories (diffusion, field, and alternating potential charging) shows, that the effect of the electrical properties (represented by the dielectric constant) of the particles affects the charging process. A non-contact method for particle charge measurement was also presented. In the second part of the chapter, the interaction between the electric field and the charged particle for the purpose of particle trapping is illustrated. The most common systems like the two or four ring electrodynamic balance and the quadrupole trap are pointed out. In Chapter 4 a short review of the possibility of using scattered light to study aerosol particles is presented. First, the conditions and the facilities of using the Mie theory for particle size and refractive index determination are mentioned, then some features concerning the classical treatment of the Raman effect are presented Supported by the theoretical considerations exposed in Chapter 2, 3, and 4 the construction and the tests of different devices are presented in Chapter 5. Following the goal of the thesis, first an overview of the used materials and methods for particle generation is presented. Then, the constructed charging devices are described (from the mechanical and electrical point of view) and compared by measuring the acquired charge on the particle. Charged particles can be trapped in different containers. Two types of axially symmetric electrodynamic balances (two ring or an extended four ring configuration) were presented. For a deeper understanding these systems were studied using analytic and numerical methods. Considering the presented purpose of the work another type of trapping system has been developed, namely the quadrupole trap. A similar theoretical characterisation (in term's of Mathieu equation) as for the electrodynamic balance was presented pointing out some specific features of this system. The incoming particle stream will be focused to the centre of the system simultaneously also the applied DC and AC potential onto the tube electrodes, yields a stable trapping of one or more particles. Chapter 6 consists of two parts: the system for single particle and for many particles investigation. The individual devices presented in Chapter 5 are now put together. The first part presents the method and the experimental realisation of a set-up for solid particle injection. In order to suppress the phase injection disadvantage found for the electrodynamic balance a developed program processes the information obtained from a particle cloud through an adequate electronic detection system, and reduces the number of particles until just one single particle is trapped. The method for one particle investigation can be extended for many particles. Using the presented set-up the particles are moved from one quadrupole to another and transformed from a particle cloud to a particle stream. A linearity between an external vertical mounted detector and the formed image of the particle stream on the CCD camera has been observed and used for simultaneous detection of many particles by Raman spectroscopy. For both methods Raman results are presented. One limitation of Raman Spectroscopy is the relatively long integration time needed for adequate signal-to-noise ratio. There are two factors which influence the integration time: first the incident radiation and the detector sensitivity, and second the intensity of the Raman bands. Using a CCD detector, the desired detector sensitivity should be achieved. So, the improvement of the signal-to-noise ratio should be the next goal in the system development. In order to reduce the integration time an optical system including optic fibres and the integration of an FT-Raman module operating in the visible region is planed. The goal of this work was to develop and construct an instrument for on-line in-situ single particle investigation by Raman spectroscopy. With the presented experimental set-up and the developed program the purpose of the work, the on-line in-situ near atmospheric pressure aerosol investigation was achieved. The Raman spectroscopy has been used successfully for a chemical characterisation of the aerosol particles.},
  subject      = {Aerosol},
  language  = {en}
}
@phdthesis{Baumeister2004,
  author    = {Baumeister, Joachim},
  title     = {Agile development of diagnostic knowledge systems},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9698},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {The success of diagnostic knowledge systems has been proved over the last decades. Nowadays, intelligent systems are embedded in machines within various domains or are used in interaction with a user for solving problems. However, although such systems have been applied very successfully the development of a knowledge system is still a critical issue. Similarly to projects dealing with customized software at a highly innovative level a precise specification often cannot be given in advance. Moreover, necessary requirements of the knowledge system can be defined not until the project has been started or are changing during the development phase. Many success factors depend on the feedback given by users, which can be provided if preliminary demonstrations of the system can be delivered as soon as possible, e.g., for interactive systems validation the duration of the system dialog. This thesis motivates that classical, document-centered approaches cannot be applied in such a setting. We cope with this problem by introducing an agile process model for developing diagnostic knowledge systems, mainly inspired by the ideas of the eXtreme Programming methodology known in software engineering. The main aim of the presented work is to simplify the engineering process for domain specialists formalizing the knowledge themselves. The engineering process is supported at a primary level by the introduction of knowledge containers, that define an organized view of knowledge contained in the system. Consequently, we provide structured procedures as a recommendation for filling these containers. The actual knowledge is acquired and formalized right from start, and the integration to runnable knowledge systems is done continuously in order to allow for an early and concrete feedback. In contrast to related prototyping approaches the validity and maintainability of the collected knowledge is ensured by appropriate test methods and restructuring techniques, respectively. Additionally, we propose learning methods to support the knowledge acquisition process sufficiently. The practical significance of the process model strongly depends on the available tools supporting the application of the process model. We present the system family d3web and especially the system d3web.KnowME as a highly integrated development environment for diagnostic knowledge systems. The process model and its activities, respectively, are evaluated in two real life applications: in a medical and in an environmental project the benefits of the agile development are clearly demonstrated.},
  language  = {en}
}
@phdthesis{Rueter2004,
  author    = {R{\"u}ter, Katja},
  title     = {The efficiency of routine standards in social comparison},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9448},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {One primary source for self-knowledge is social comparison. Often objective criteria for self-evaluations are not available or useful and therefore comparisons with other people play a crucial role in self-evaluations. But the question is whether social comparisons could indeed provide information about the self without consuming too much cognitive resources or time. Therefore, in this research I wanted to look at practice effects in social comparison and the particular significance of routine standards. Whereas traditional research on standard selection mostly focused on goal-oriented and strategic standard selection processes, this research sets out to integrate social cognitive knowledge, ideas, and methods. Researchers from many different fields agree that people's behavior and thinking is not fully determined by rational choices or normative considerations. Quite the contrary, factors like knowledge accessibility, habits, procedural practice, stereotyping, categorization, and many more cognitive processes play an important role. The same may be true in social comparison and standard selection. In my research I demonstrate that efficiency concerns play an important role in social comparison. Since people may not be able to engage in a strategic standard selection whenever they engage in social comparison processes, there has to be a more efficient alternative. Using routine standards would be such an alternative. The efficiency advantage of routine standards may thereby be founded not only in the abandonment of a strategic but arduous standard selection process, but also in a higher efficiency of the comparison process itself. I therefore set out to show how the use of routine standards facilitates the social comparison processes. This was done in three steps. First, I replicated and improved our former research (Mussweiler \& R{\"u}ter, 2003, JPSP) indicating that people really do use their best friends as routine standards to evaluate themselves. Second, I demonstrated that it is more efficient to compare with a routine standard than with another standard. In Studies 2 and 3 I therefore show that comparisons between the self and a routine standard (either a natural routine standard like the best friend or a experimentally induced routine standard based on practice) are faster and more efficient than comparisons with other standards. Finally, I looked at the underlying mechanism of the efficiency advantage of routine standards. The results of Studies 4 and 5 point out, that both general as well as specific practice effects occur with repeated comparisons. Whereas a specific practice effect implies the repeated processing of the same content (i.e., knowledge about the routine standard), general practice effects indicate that the pure process (i.e., comparing the self with a routine standard) becomes more efficient regardless whether new content (i.e., comparison relevant knowledge) has to be processed. Taken together, the efficiency advantage of routine standards during self-evaluation is based not only on the lack of necessity for an arduous standard selection, but is additionally supported by the facilitation of the comparison process itself. The efficiency of routine standards may provide an explanation as to why people base self-evaluations on comparisons with these standards and dispense with strategic considerations to select the most suitable standard.},
  language  = {en}
}
@phdthesis{Tyrsin2003,
  author    = {Tyrsin, Oleg},
  title     = {Role of Raf family members in mouse development},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9453},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2003},
  abstract  = {Raf Proteine sind Serin/Threonin Kinasen, die als zentrale Elemente des Ras, Raf, Mek, Map Kinase Wegs, an der Weiterleitung von extrazellul{\"a}ren Signalen von der Zellmembran zu nukle{\"a}ren Effektoren beteiligt sind. Auf diese Weise kontrollieren sie elementare Prozesse wie Proliferation, Differenzierung und das {\"U}berleben von Zellen. In S{\"a}ugetieren wurden drei funktionelle Gene (A-, B- and C-raf) beschrieben. Aus biochemischen Untersuchungen ergibt sich, dass die Isozyme {\"u}berlappende aber auch differentielle Funktionen {\"u}bernehmen. Allerdings wurde ein differenziertes Verst{\"a}ndnis der jeweiligen spezifischen Rolle dadurch erschwert, dass in den meisten Zelltypen verschiedene Raf-Isozyme expremiert werden und dass wegen der Vielzahl der Aktivatoren und Effektoren eine eindeutige Isoform-Zuordnung schwer m{\"o}glich war. Aufgrund der Beteiligung an verschiedenen Krankheitsbildern, insbesondere der Tumorentstehung und -progression, ist jedoch die Aufkl{\"a}rung der Isozym-spezifischen Funktionen von vorranginger wissenschaftlicher Bedeutung. B-Raf hat unter den Raf Kinasen die h{\"o}chste Kinaseaktivit{\"a}t und zeigt antiapoptotische Eigenschaften. B-Raf knockout M{\"a}use zeigen eine allgemeine Wachstumsverz{\"o}gerung und sterben zwischen E10,5 und E12,5 aufgrund fehlentwickelter Gef{\"a}sse in Folge massiver Apoptose differenzierter Endothelzellen. [1]. Um die Lethalit{\"a}t des B-Raf-/- (KO) Ph{\"a}notyps zu {\"u}berkommen und um die Redundanz der B-Raf Proteine weiter zu untersuchen, wurden M{\"a}use generiert, die unter der Kontrolle des B-Raf Promoters statt B-Raf eine A-Raf cDNA exprimieren. Nur in einem Fall entwickelte sich eine ausgewachsene p20 Maus ohne sichtbare Entwicklungsdefekte oder Verhaltensauff{\"a}lligkeiten. Dar{\"u}ber hinaus wurden lebende Embryonen mit normaler Entwicklung aber reduzierter Gr{\"o}sse mit niedriger Inzidenz zwischen E12,5d und E16,5d beobachtet. In allen diesen F{\"a}llen fanden wir ein intaktes Gef{\"a}ßsystem. Andererseits waren Neurogenese und die Bewegung der neuralen Vorl{\"a}uferzellen in den {\"u}berlebenden Embryonen gest{\"o}rt, was in einigen F{\"a}llen zu unterentwickelten Hirnregionen f{\"u}hrte. Mittels TUNEL bzw. PCNA Assay konnten wir zeigen, dass mehr apoptotische und weniger proliferierende Zellen in ventrikul{\"a}rer und subventrikul{\"a}rer Zone der Hirn Ventrikel und im Striatum der KIN Embryonen zu finden sind. Außerdem wurden in einer Reihe von Geweben von E13,5d und in den Lungen von E16,5d Embryonen, vermehrt apoptotische Zellen beobachtet. Dies war in der einen ausgewachsenen KIN Maus nicht der Fall. Diese zeigte einen reduzierten Anteil an neuronalen Vorl{\"a}uferzellen in der subgranul{\"a}ren Zone des Hippocampus und an reifen Neuronen im Riechkolben. Ansonsten waren aber keine St{\"o}rungen der Neurogenese in der ausgewachsenen KIN Maus detektierbar. Fibroblasten die aus KIN Embryonen etabliert wurden, zeigten im Vergleich zu Wildtypzellen reduzierte F{\"a}higkeit zur Proliferation und erh{\"o}hte Sensibilit{\"a}t gegen{\"u}ber Apoptoseausl{\"o}sern. Die erh{\"o}hte Apoptosetendenz spiegelte sich auf molekularer Ebene in einer Reduktion an antiapoptotischen Molek{\"u}len wieder. Aktive ERK und Akt Kinase sind erniedrigt. Außerdem war von dem bekannten Raf Substrat BAD, weniger an der inaktiven phosphorylierten Form zu beobachten, wodurch bei gleicher Menge Gesamtprotein auf ein Mehr an proapoptotischem unphosphoryliertem BAD geschlossen werden kann. Zusammengefasst zeigen diese Daten, dass die Substitution von B-Raf durch die weniger aktive A-Raf Kinase zwar die endotheliale Apoptose verhindern kann, die die Ursache f{\"u}r das fr{\"u}he Absterben der B-Raf-/- (KO) M{\"a}use ist, dass aber die normale Entwicklung dennoch entscheidend gest{\"o}rt ist.},
  subject      = {Maus},
  language  = {en}
}
@phdthesis{Kahlenberg2004,
  author    = {Kahlenberg, Frank},
  title     = {Structure-property correlations in fluoroaryl functionalized inorganic-organic hybrid polymers for telecom applications},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9378},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {The development and in-depth characterization of new fluoroaryl functionalized ORMOCER® materials (inorganic-organic hybrid polymers) for optical waveguide applications in telecommunication is presented. The preparation of the materials included precursor silane synthesis, hydrolysis/polycondensation of organoalkoxysilane mixtures, and photolithographic processing of the resulting oligosiloxane resins in order to establish the inorganic-organic hybrid network. During all stages of ORMOCER® preparation, structure-property relations were deduced from characterization data, particularly with respect to low optical loss in the important near-infrared spectral region as well as refractive index. With the aid of molecular modeling, structural characteristics of oligomeric intermediates were visualized, which was found valuable in the fundamental understanding of the material class. The material development started with the syntheses of a variety of commercially unavailable fluorinated and unfluorinated arylalkoxysilanes by means of Grignard and hydrosilylation pathways, respectively. A survey of silane optical properties, particularly their absorptions at the telecom wavelengths 1310 nm and 1550 nm, gave an impulse to the choice of suitable precursors for the preparation of low-loss ORMOCER® resins. Accordingly, precursor silane mixtures and hydrolysis/polycondensation reaction conditions were chosen and optimized with regard to low contents of C-H and Si-OH functions. Thus, absorptions as low as 0.04 dB/cm at 1310 nm and 0.18 dB/cm at 1550 nm, respectively, could be obtained from an oligosiloxane resin based on pentafluorophenyltrimethoxysilane (1) mixed with pentafluorophenyl(vinyl)-dimethoxysilane (5). In order to improve the organic crosslinkability under photolithographic processing conditions, further resins on the basis of the aforementioned were prepared, which additionally incorporated the styrene-analogous precursor 4-vinyltetrafluorophenyl-trimethoxysilane (4). Thus, ORMOCER® resins with low optical losses of 0.28 dB/cm at 1310 nm and 0.42 dB/cm at 1550 nm, respectively, were prepared, which exhibited excellent photopatternability. The manufacture of micropatterns such as optical waveguide structures by UV-photolithography under clean room conditions was the final stage of material synthesis. The optimization of processing parameters allowed the preparation of test patterns for the determination of optical, dielectrical and mechanical properties. A low optical loss of 0.51 dB/cm at 1550 nm could be measured on a waveguide manufactured from a photopatternable fluoroaryl functionalized ORMOCER®. The structural characterization of liquid resins as well as cured ORMOCER® samples was accomplished chiefly with solution and solid state 29Si-NMR spectroscopy, respectively. Particularly for polycondensates incorporating species based on more than one precursor silane, the spectra showed a high degree of complexity. An additional challenge arouse from the partial loss of fluoroaryl groups during ORMOCER® condensation and curing, which resulted in even more condensation products. Thus, in order to provide a basis for resin analysis, first the hydrolysis/condensation reactions of the isolated precursors were investigated under reaction time-resolution with NMR spectroscopy at low temperature. Backed by signal assignments in these single-precursor systems, the respective species could also be identified in the complex resin spectra, allowing for their quantitative interpretation. The structural characterization was rounded out by IR spectroscopy and SAXS analyses. With the help of molecular modeling, the experimental data were finally transferred into a three-dimensional image of an organosiloxane oligomer, which is representative for a photopatternable fluoroaryl functionalized ORMOCER® resin. The combination of low-temperature NMR, which made the characterization of polycondensates possible, with oligomer modeling paved the way to a further understanding of ORMOCER® resin systems. On the basis of this visualization of structural characteristics, e.g. properties such as organic crosslinkability of oligomers were discussed in the light of steric features within the molecular structure. Thus, new possibilities were established for the systematic optimization of ORMOCER® formulations. Structure-property relations with respect to optical loss and refraction, as determined within this work, follow trends, which are in accordance with the literature. Particularly the direct comparison of data derived from analogous fluorinated and unfluorinated ORMOCER® resins showed that fluorination results in significant decrease in NIR optical loss. Additionally, different unfluorinated aryl functionalized systems with varying aliphatic C-H content were compared. In case of a lower aliphatic content, a widening effect on the 1310 nm window was found. This is due to a shift of arylic C-H vibrations (1145 nm) towards lower wavelengths compared to aliphatic C-H (1188 nm). Finally, on the basis of NIR spectra of analogous fluorinated resins with low and high silanol content, respectively, a significant impact of (Si)O-H groups on the 1550 nm window was demonstrated, while the 1310 nm window was unaffected. This is due to O-H vibrations with a maximum at 1387 nm and further bands at higher wavelength. The index of refraction was drastically lowered due to fluorination. Thus, the analogous fluorinated and unfluorinated ORMOCER® resins had indices of 1.497 and 1.570, respectively, in the VIS region. For the fluorinated systems, refraction did not change significantly during organic cross-connection and hardbake. In conclusion, the new fluoroaryl functionalized ORMOCER® systems represent low-loss materials for telecom applications. In addition, in-depth characterization during material development allowed the proposal of structure-property relations, particularly with respect to optical properties, which are of considerable importance for future developments.},
  subject      = {Ormocer},
  language  = {en}
}
@phdthesis{Tarcea2004,
  author    = {Tarcea, Nicolae},
  title     = {Light as a universal tool : Microcapsule sizing by elastic light scattering and mineral investigation by in situ Raman spectroscopy},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9383},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {The present work consist of two major parts. The first part, extending over chapters 1, 2, 3 and 4, addresses the design and construction of a device capable of determining the shell thickness and the core size for monolayer spherical particles in a flow. The second part containing chapters 5, 6, 7, 8, 9 and 10, concentrate on the use of Raman spectroscopy as a space application, namely for use as a tool for in situ planetary investigations. This part directly addresses the MIRAS project, a study run under the auspices of Federal Ministry of Education and Research, BMBF and German Aerospace Center, DLR under national registration number 50OW0103. MIRAS stands for "Mineral Investigation by in situ Raman Spectroscopy". Microcapsule Sizing by Elastic Light Scattering The industrial development of processes based on microcapsules depends on the possibility to provide clear and complete information about the properties of these microcapsules. However, the tools for an easy and efficient determination of the microcapsule properties are lacking, several methods being often required to describe adequately the microcapsule behavior. Methods for evaluating the individual size and size distribution of both the core and the shell are required together with methods for measuring the mechanical strength, stability in appli-cation media, permeability of the shell, etc. Elastic light scattering measurements provide a possible way of determining properties such as core size, shell size and refractive index. The design and con-struction of a device capable of measuring the above mentioned parameters for a core-shell particle is the subject of the first part of this thesis. The basic principle of measurement for the device proposed here consists of an-alyzing one particle at a time by recording the elastic light scattering pattern at angles between approx. 60 and 120 grad. By comparing the experimentally recorded phase functions with the previously calculated phase functions stored in a database, the geometry of the scattering object can be identified. In our case the geometry is characterized by two parameters: the shell thickness and the core radius. In chapter 2 a short overview on the methods used for sizing microparticles is given. Different sizing methods are compared, and the advantages and disadvan-tages for the general problem of sizing are shortly discussed. It is observed that all sizing methods that are based on elastic light scattering theories are ensemble methods. Chapter 3 focusses on the theories used for calculating the theoretical scattering patterns with emphasize on the Mie theory. The generalization of Mie theory for layered particles is shortly presented and the far field intensity approximations are discussed. The last chapter (4) of this first part describes the experimental approach for building an automatic microcapsule sizer. The approach started by O. Sbanski [76] with the development of a software packet for calculating and storing theoret-ical phase functions for core-shell particles was continued with the designing and construction of a measuring device. The hardware construction and the software with all implemented corrections imposed by the individual setup components are described in detail. For the laser, the monochromaticity, the intensity profile of the beam as well as the planarity of the equi-phase fronts are taken into consid-eration. The flow cell with three different designs is described, and the influences of the employed design on the light scattering patterns are discussed together with the optical system used for recording the experimental phase functions. The detection system formed by two identical linear CCD arrays is presented together with the software approach used for data acquisition. Ways of improving the quality and the speed of the analyzing process are discussed. The final section presents measurements run on samples made of homogeneous spheres and also on samples containing industrial microcapsules. Mineral Investigation by in situ Raman Spectroscopy The envisaged future planetary missions require space-born instruments, which are highly miniaturized with respect to volume and mass and which have low needs of power. A micro Raman spectrometer as a stand alone device on a planetary surface (e.g. Mars) offers a wide spectrum of possibilities. It can assess the chemical analysis via determination of the mineral composition, detect organic molecules in the soil, identify the principal mineral phases, etc. The technical developments in the last years have introduced a new generation of small Raman systems suitable for robotic mineral characterization on planetary surfaces [20, 95]. Two different types of spectrometer were considered for the MIRAS study. As supporting laboratory experiments for the MIRAS study, the measure-ments on standard minerals and on SNC Mars meteorites are discussed in chapter 6. The following SNC meteorites have been investigated: Sayh al Uhaymir 060, Dar al Gani 735, Dar al Gani 476, Northwest Africa 856, Los Angeles, Northwest Africa 1068 and Zagami. Pyrite as a hitherto undescribed phase in the picritic (olivin-phyric) shergottite NWA 1068 as well as reduced carbon (e.g. graphite) and anatase in the shergottite Say al Uhaymir 060 are new findings for this class of meteorites. A detailed description of the proposed designs for MIRAS, with the compo-nents used for building the test version on a breadboard is covered in chapter 7. The scientific as well as the mission requirements imposed on the instrument are discussed. The basic design is presented and the main components that are brought together to build the device being the laser unit, the Raman head, the Rayleigh filtering box, and the spectral sensor (spectrometer with a matching de-tector) are described. The two proposed designs, one based on an acousto-optic tunable filter (AOTF) and the other based on a dispersive hadamard transform spectrometer are compared to each other. The actual breadboard setup with the detailed description of the components follows in Section 7.3. Further de-velopment of a Raman spectrometer for planetary investigations is proposed in combination with a microscope as part of the Extended-MIRAS project. The software developed for controlling the breadboard version of MIRAS is described in chapter 8 together with a short description of the structure of a relational database used for in house spectra management. The measuring pro-cedures and the data processing steps are presented. Spectra acquired with the MIRAS breadboard version based on the AOTF are shown in chapter 9. The final chapter addresses a rather different possibility of using Raman spectroscopy for planetary investigations. The chapter summarizes the content of four tech-nical notes that were established within the study contracted by the European Space Agency with firma Kayser-Threde in Munich concerning the possibility of applying Raman spectroscopy in the field of remote imaging.},
  language  = {en}
}
@phdthesis{Geiger2004,
  author    = {Geiger, Lars},
  title     = {The versatile use of Guanidiniocarbonylpyrroles : from self-assembly to peptide recognition},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9272},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {Die vorliegende Arbeit gliedert sich in zwei Themenschwerpunkte. Ein supramolekulares Projekt beinhaltete die Entwicklung von neuen flexiblen, selbst-aggregierenden Zwitterionen als Bausteine f{\"u}r supramolekulare Polymere. In einem zweiten bioorganischem Teil bestand das Ziel darin, Rezeptoren f{\"u}r Aminos{\"a}uren und Dipeptide in Wasser zu entwickeln. Beide Projekte basieren auf dem Guanidiniocarbonylpyrrol als effizientes Bindungsmotiv f{\"u}r die Komplexierung von Carboxylaten in w{\"a}ssrigen L{\"o}sungen. Eine notwendige Voraussetzung f{\"u}r die Realisierung dieser Projekte war jedoch zun{\"a}chst die Entwicklung einer allgemeinen, effizienten und milden Synthese f{\"u}r Guanidiniocarbonylpyrrole. Die bei der zuvor verwendeten Methode aggressiven Reaktionsbedingungen und die problematische Aufreinigung verhinderten eine gr{\"o}ßere Anwendung dieses Bindungsmotivs in bioorganischen und supramolekularen Projekten. Im Rahmen dieser Arbeit gelang es mir erfolgreich eine neue Syntheseroute zu entwickeln. Hierbei wurde mono-tBoc-Guanidine mit dem Benzylester mittels PyBOP gekuppelt und nach Entsch{\"u}tzung der Benzylschutzgruppe wurde die zentrale Zwischenstufe f{\"u}r die weiteren Synthesen, die tBoc-gesch{\"u}tzte Guanidinocarbonylpyrrol-S{\"a}ure erhalten. Durch diese neuartige Synthese war es m{\"o}glich, eine Reihe von flexiblen Zwitterionen 3-6 herzustellen und deren Selbst-Aggregation und den Einfluß der Kettenl{\"a}nge und somit Flexibilit{\"a}t der Alkylkette auf Struktur und Stabilit{\"a}t der gebildeten Aggregate in L{\"o}sung sowie auch in der Gasphase zu untersuchen. In DMSO deuten NMR-Verd{\"u}nnungsreihen darauf hin, dass die flexiblen Zwitterionen mit n = 1, 3 und 5 oligomere Strukturen ausbilden. Im Falle von n = 1 werden hoch stabile helicale und Nanometer große Aggregate in der gebildet. In den Gasphasen-Studien wurde die Stabilit{\"a}t und Zerfallskinetik einer Reihe von Natriumaddukten der Dimere von n = 2, 3 und 5 untersucht. Dieses gelang durch die Methode der „infrared multiphoton dissociation Fourier transform ion cyclotron resonance mass spectrometry" (IRMPD-FT-ICR MS). Solche Studien erm{\"o}glichen m{\"o}glicherweise in Zukunft das gezielte Design von supramolekularen Bausteinen. Der bioorganische Teil meiner Arbeit setzte sich aus drei Einzelprojekten zusammen. So synthetisierte ich durch eine f{\"u}nfstufige Synthesesequenz vier neue Arginin-Analoga, die in Zukunft als Ersatz f{\"u}r Arginin in Peptide eingebaut werden k{\"o}nnen. Als Testreaktion f{\"u}r die Eignung dieser Verbindungen in einer Festphasenpeptidsynthese, wurde ein Tripetid Ala-AA1-Val (AA: Arginin-Analogon) mit einem eingebauten Arginin-Analogon erfolgreich hergestellt. In einem zweiten Projekt habe ich den Einfluß einer zus{\"a}tzlichen ionischen Wechselwirkung in unserem Bindungsmotiv untersucht. Dazu wurde ein zweifach-kationischer Rezeptor und der dreifach-geladenen Rezeptor synthetisiert und physikalisch-organisch ihre Bindungseigenschaften mit Hilfe von NMR-Titrationsexperimenten gegen eine Reihe von Aminos{\"a}uren untersucht. Der dreifach-kationische Rezeptor 11 zeigte hierbei herausragende Bindungseigenschaften und war um ca. den Faktor 100 besser als f{\"u}r die bisher bekannten Guanidiniocarbonylpyrrole. Die Assoziationskonstanten waren auch fast reinem Wasser mit bis zu Kass = 2000 noch bemerkenswert hoch. Im dritten Projekt habe ich einen de-novo entwickelten Rezeptor f{\"u}r C-terminale Dipeptide in einer beta-Faltblatt Struktur entwickelt.Dieser Rezeptor wurde mittels NMR and UV-Titrationen untersucht. In 40 \% Wasser/ 60 \% DMSO waren die Bindungskonstanten zu hoch um {\"u}berhaupt quantifiziert zu werden. Deshalb wurden die Bindungseigenschaften des Rezeptors mittels UV Titrationen in einer Mischung aus 90 \% Wasser mit 10 \% DMSO gegen eine Reihe von Dipeptiden und Aminos{\"a}uren getestet. Die Bindungsdaten zeigen, dass Rezeptor Dipeptide mit ausgezeichneten Bindungskonstanten (Kass > 10000 M-1) komplexiert. Im Gegensatz dazu bindet der Rezeptor 12 Aminos{\"a}uren um den Faktor zehn schlechter (Kass > 1000 M-1). Die Komplexstabilit{\"a}t nimmt hierbei in Abh{\"a}ngigkeit von der Seitenkette des Dipeptids in der Reihe Gly < Ala < Val zu, was sich mit der abnehmenden Flexibilit{\"a}t und zunehmenden Hydrophobizit{\"a}t der Seitenkette erkl{\"a}ren l{\"a}sst. Diese Eigenschaften machen den Rezeptor 12 zu dem besten bisher bekannten Dipeptidrezeptor in w{\"a}ssrigen L{\"o}sungen. Innerhalb meiner Arbeit gelang es mir somit, nicht nur eine essentiell wichtige, milde und effiziente Synthese f{\"u}r Guanidinocarbonylpyrrole zu entwickeln, sondern es gelang mir ebenso ein neues Bindungsmotiv f{\"u}r die Komplexierung von Aminos{\"a}uren in Wasser zu entwickeln. Zus{\"a}tzlich konnte noch der Dipeptidrezeptor erfolgreich synthetisiert und untersucht werden. Mit Bindungskonstanten f{\"u}r von Kass > 10000 M-1 ist er der derzeit beste Dipeptidrezeptor in w{\"a}ssriger L{\"o}sung.},
  subject      = {Guanidinderivate},
  language  = {en}
}
@phdthesis{Planchet2004,
  author    = {Planchet, Elisabeth},
  title     = {Nitric oxide production by tobacco plants and cell cultures under normal conditions and under stress},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9339},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {Stickstoffmonoxid (NO) ist ein gasf{\"o}rmiges freies Radikal. In tierischen Geweben ist NO an der Regulation vieler physiologischer Prozesse beteiligt. In den letzten zehn Jahren wurde immer wahrscheinlicher, dass NO auch in Pflanzen als „second messenger" fungiert. Besonderes Interesse fanden Berichte, dass NO als intermedi{\"a}res Signal bei der Induktion der hypersensitiven Antwort (HR) von Pflanzen auf Pathogene involviert ist. Im Gegensatz zu Tieren haben Pflanzen wahrscheinlich eine Reihe verschiedener Systeme, die NO produzieren k{\"o}nnen. Potentielle Kandidaten daf{\"u}r sind: cytosolische Nitratreduktase (NR; EC 1.6.6.1), PM-gebundene Nitrit: NO Reduktase (Ni:NOR), NO-Synthase (NOS; EC 1.14.13.39) und Xanthindehydrogenase (XDH; EC 1.1.1.204). Das Ziel dieser Arbeit bestand darin, die NO-Produktion von Pflanzen zu quantifizieren und die beteiligten enzymatischen Schritte zu identifizieren. Als wichtigste Methode zur NO-Messung wurde die Chemilumineszenz verwendet, mit der die NO Emission aus Pflanzen, Zellsuspensionen oder Enzyml{\"o}sungen in NO-freie Luft oder N2 in Echtzeit verfolgt werden konnte. Wir benutzten f{\"u}r unsere Analyse: Tabak Wildtyp (N. tabacum cv Xanthi oder cv Gatersleben) und Zellsuspensionskulturen davon, NR-freie Mutanten oder WT Pflanzen, die auf Ammonium angezogen wurden um NR-Induktion zu vermeiden, Pflanzen die auf Wolframat an Stelle von Molybdat wuchsen um die Synthese funktionierender MoCo-Enzyme zu unterdr{\"u}cken, und eine NO-{\"u}berproduzierende, Nitritreduktase (NiR)-defiziente Transformante. Normale Bl{\"a}tter von nitratern{\"a}hrten Pflanzen zeigten eine typisches NO-Emissionsmuster,bei dem die NO-Emission im Dunkeln niedrig, im Licht viel h{\"o}her, und unter anoxischen Bedingungen im Dunkeln mit weitem Abstand am h{\"o}chsten war. Aber selbst nach Erreichen maximaler Raten war die NO-Emission h{\"o}chstens 1 \% der extrahierbaren NR Aktivit{\"a}t. Auch eine L{\"o}sung hochgereinigter Nitratreduktase produzierte NO aus den Substraten Nitrit und NADH, und auch hier war die Rate der NO-Emission nur maximal 1\% der vorhandenen NR-Aktivit{\"a}t. Dieses {\"u}bereinstimmende Verh{\"a}ltnis von NR Aktivit{\"a}t und NO-Emission in Bl{\"a}ttern, Zellsuspensionen und einer NR-L{\"o}sung zeigt an dass die NO-L{\"o}schung nur gering war und dass deshalb die NO-Emissionsmessung eine zuverl{\"a}ssige Methode zur Quantifizierung der NO Produktion sein sollte. Die NO-Emission aus einer NiR-defizienten, nitritakkumulierenden Transformante warimmer sehr hoch. NR-freie Pflanzen oder Zellsuspensionen produzierten dagegen normalerweise kein NO, woraus geschlossen werden konnte, dass hier NR die einzige NOQuelle war. Die Rate war in der Regel korreliert mit der Nitritkonzentration, aber cytosolisches NADH erschien als ein weiterer wichtiger limitierender Faktor.{\"U}berraschenderweise reduzierten aber auch NR-freie Pflanzen oder Zellkulturen unter anoxischen Bedingungen Nitrit zu NO. Das beteiligte Enzymsystem war kein MoCo-Enzym und war Cyanid-sensitiv. Der pilzliche Elicitor Cryptogein induzierte nach Infiltration in Bl{\"a}tter oder nach Zugabe zu Zellsuspensionen bereits in nanomolaren Konzentrationen den Zelltod. Diese Antwort wurde verhindert oder zumindest stark verz{\"o}gert durch den NO-Scavenger PTIO oder c-PTIO. Die Schlussfolgerung war zun{\"a}chst, das NO tats{\"a}chlich an der HR-Induktion involviert war. Da aber das Reaktionsprodukt von c-PTIO und NO, c-PTI, den HR ebenfalls verhinderte ohne jedoch NO zu l{\"o}schen, scheint die weit verbreitete Verwendung von c-PTIO und seinen Derivaten f{\"u}r die Beweisf{\"u}hrung einer Beteiligung von NO zumindest fragw{\"u}rdig. Der HR wurde unterschiedslos sowohl in WT-Pflanzen als auch in NR-freien Pflanzen bzw. Zellsuspensionen induziert. NR ist also offensichtlich f{\"u}r den HR nicht erforderlich. Im Gegensatz zur publizierten Literaturdaten verhinderte auch eine kontinuierliche hohe {\"U}berproduktion von NO die Auspr{\"a}gung des HR nicht. Besonders {\"u}berraschend war der Befund, dass trotz der Hemmung des HR durch PTIO keinerlei Cryptogein-induzierte NO Produktion in Bl{\"a}ttern messbar war. Allerdings wurde in nitratern{\"a}hrten Zellsuspensionskulturen ca. 3-6 h nach Cryptogein-Gabe eine -wenn auch geringe-NOEmission beobachtet, die von einer Nitritakkumulation begleitet war. Beides blieb in Ammonium-ern{\"a}hrten Kulturen aus. Hier schien also eine gewisse Relation zwischen Cryptogein-induzierter NO Emission, NR und Nitrit zu bestehen, die im Detail noch nicht verstanden ist. Da der Zelltod aber auch in NR-freien Zellsuspensionskulturen auftrat, besteht offensichtlich kein kausaler Zusammenhang zwischen dieser NO-Emission, Nitritakkumulation und der Cryptogein-Wirkung. Da NOS-Inhibitoren weder den Zelltod noch die nitritanh{\"a}ngige NO-Emission verhinderten, scheint eine NOS-artige Aktivit{\"a}t ebenfalls keine Rolle zu spielen. Insgesamt werden damit die in der Literatur etablierte Rolle von NO als Signal beim HR und die Rolle von NOS als NO-Quelle stark in Frage gestellt.},
  subject      = {Tabak},
  language  = {en}
}
@phdthesis{Kraus2003,
  author    = {Kraus, Daniela},
  title     = {Conformal pseudo-metrics and some applications},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9193},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2003},
  abstract  = {The point of departure for the present work has been the following free boundary value problem for analytic functions \$f\$ which are defined on a domain \$G \subset \mathbb{C}\$ and map into the unit disk \$\mathbb{D}= \{z \in \mathbb{C} : |z|<1 \}\$. Problem 1: Let \$z_1, \ldots, z_n\$ be finitely many points in a bounded simply connected domain \$G \subset \mathbb{C}\$. Show that there exists a holomorphic function \$f:G \to \mathbb{D}\$ with critical points \$z_j\$ (counted with multiplicities) and no others such that \$\lim_{z \to \xi} \frac{|f'(z)|}{1-|f(z)|^2}=1\$ for all \$\xi \in \partial G\$. If \$G=\mathbb{D}\$, Problem 1 was solved by K?nau [5] in the case of one critical point, and for more than one critical point by Fournier and Ruscheweyh [3]. The method employed by K?nau, Fournier and Ruscheweyh easily extends to more general domains \$G\$, say bounded by a Dini-smooth Jordan curve, but does not work for arbitrary bounded simply connected domains. In this paper we present a new approach to Problem 1, which shows that this boundary value problem is not an isolated question in complex analysis, but is intimately connected to a number of basic open problems in conformal geometry and non-linear PDE. One of our results is a solution to Problem 1 for arbitrary simply connected domains. However, we shall see that our approach has also some other ramifications, for instance to a well-known problem due to Rellich and Wittich in PDE. Roughly speaking, this paper is broken down into two parts. In a first step we construct a conformal metric in a bounded regular domain \$G\subset \mathbb{C}\$ with prescribed non-positive Gaussian curvature \$k(z)\$ and prescribed singularities by solving the first boundary value problem for the Gaussian curvature equation \$\Delta u =-k(z) e^{2u}\$ in \$G\$ with prescribed singularities and continuous boundary data. This is related to the Berger-Nirenberg problem in Riemannian geometry, the question which functions on a surface R can arise as the Gaussian curvature of a Riemannian metric on R. The special case, where \$k(z)=-4\$ and the domain \$G\$ is bounded by finitely many analytic Jordan curves was treated by Heins [4]. In a second step we show every conformal pseudo-metric on a simply connected domain \$G\subseteq \mathbb{C}\$ with constant negative Gaussian curvature and isolated zeros of integer order is the pullback of the hyperbolic metric on \$\mathbb{D}\$ under an analytic map \$f:G \to \mathbb{D}\$. This extends a theorem of Liouville which deals with the case that the pseudo-metric has no zeros at all. These two steps together allow a complete solution of Problem 1. Contents: Chapter I contains the statement of the main results and connects them with some old and new problems in complex analysis, conformal geometry and PDE: the Uniformization Theorem for Riemann surfaces, the problem of Schwarz-Picard, the Berger-Nirenberg problem, Wittich's problem, etc.. Chapter II and III have preparatory character. In Chapter II we recall some basic results about ordinary differential equations in the complex plane. In our presentation we follow Laine [6], but we have reorganized the material and present a self-contained account of the basic features of Riccati, Schwarzian and second order differential equations. In Chapter III we discuss the first boundary value problem for the Poisson equation. We shall need to consider this problem in the most general situation, which does not seem to be covered in a satisfactory way in the existing literature, see [1,2]. In Chapter IV we turn to a discussion of conformal pseudo-metrics in planar domains. We focus on conformal metrics with prescribed singularities and prescribed non-positive Gaussian curvature. We shall establish the existence of such metrics, that is, we solve the corresponding Gaussian curvature equation by making use of the results of Chapter III. In Chapter V we show that every constantly curved pseudo-metric can be represented as the pullback of either the hyperbolic, the euclidean or the spherical metric under an analytic map. This is proved by using the results of Chapter II. Finally we give in Chapter VI some applications of our results. [1,2] Courant, H., Hilbert, D., Methoden der Mathematischen Physik, Erster/ Zweiter Band, Springer-Verlag, Berlin, 1931/1937. [3] Fournier, R., Ruscheweyh, St., Free boundary value problems for analytic functions in the closed unit disk, Proc. Amer. Math. Soc. (1999), 127 no. 11, 3287-3294. [4] Heins, M., On a class of conformal metrics, Nagoya Math. J. (1962), 21, 1-60. [5] K?nau, R., L?gentreue Randverzerrung bei analytischer Abbildung in hyperbolischer und sph?ischer Geometrie, Mitt. Math. Sem. Giessen (1997), 229, 45-53. [6] Laine, I., Nevanlinna Theory and Complex Differential Equations, de Gruyter, Berlin - New York, 1993.},
  subject      = {Freies Randwertproblem},
  language  = {en}
}
@phdthesis{Petrovic2004,
  author    = {Petrovic, Suzana},
  title     = {In vivo analysis of homing pattern and differentiation potential of cells deriving from embryonic and adult haematopoietic regions},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9323},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {The experimental work of this thesis addresses the questions of whether established cell lines injected into murine blastocysts find their way back home and seed preferentially at the site of their origin. Furthermore, can they change their fate and differentiate to unrelated cell types when exposed to the embryonic environment. This survey was based on the fact that different cell lines have different potentials in developing embryos, dependent on their cellular identity. The cell lines used in this survey were AGM region-deriving DAS 104-4, DAS 104-8 cells, yolk sac-deriving YSE cells and bone marrow-deriving FDCP mix cells. These cells were injected into mouse blastocysts. Donor cells were traced in developing embryos via specific markers. Analysis of the embryos revealed that DAS cells are promiscuous in their seeding pattern, since they were found in all analysed tissues with similar frequencies. YSE cells showed preferences in seeding yolk sac and liver. YSE donor cells in chimaeric tissues were not able to change their immuno-phenotype, indicating that they did not change their destiny. Analysis of adult mice did not reveal any of YSE-derived cells donor contribution. In contrast, FDCP mix cells mostly engrafted haematopoietic tissues, although the embryos analysed by in situ hybridization had donor signals frequently in cartilage primordia, heads, and livers. Analysis of whether FDCPmix-derived cells found in foetal livers were of haematopoietic or hepatocytes nature showed that progeny of injected FDCP mix cells do not differentiate into cells that express a hepatocyte-specific marker. Further analysis showed that FDCPmix-derived donor cells found in brain express neural or haematopoietic markers. In order to reveal if they transdifferentiate to neurons or fuse with neurons/glial cells, nuclear diameters of donor and recipient cells were determined. Comparison of the nuclear diameters of recipient and donor cells revealed no differences. Therefore this suggests that progeny of FDCP mix in brain are not fusion products. Analysis of adult mice tissues revealed that presence of FDCP mix-derived cells was the highest in brains. These results confirmed the assumption that the developmental potential of the analysed cells cannot be easily modified, even when exposed to early embryonic environment. Therefore one can conclude that the analysed cell types had different homing patterns depending on their origins.},
  subject      = {Zelllinie},
  language  = {en}
}
@phdthesis{Rouziere2004,
  author    = {Rouzi{\`e}re, Anne-Sophie},
  title     = {MODULATION OF THE B-CELL REPERTOIRE IN RHEUMATOID ARTHRITIS BY TRANSIENT B-CELL DEPLETION},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9290},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {Although the role of B-cells in autoimmunity is not completely understood, their importance in the pathogenesis of autoimmune diseases has been more appreciated in the past few years. It is now well known that they have roles in addition to (auto) antibody production and are involved by different mechanisms in the regulation of T-cell mediated autoimmune disorders. The evolution of an autoimmune disease is a dynamic process, which takes a course of years during which complex immunoregulatory mechanisms shape the immune repertoire until the development of clinical disease. During this course, the B-cell repertoire itself is influenced and a change in the distribution of immunoglobulin heavy and light chain genes can be observed. B-cell depletive therapies have beneficial effects in patients suffering from rheumatoid arthritis (RA), highlighting also the central role of B-cells in the pathogenesis of this disease. Nevertheless, the mechanism of action is unclear. It has been hypothesised that B-cell depletion is able to reset deviated humoral immunity. Therefore we wanted to investigate if transient B-cell depletion results in changes of the peripheral B-cell receptor repertoire. To address this issue, expressed immunoglobulin genes of two patients suffering from RA were analysed; one patient for the heavy chain repertoire (patient H), one patient for the light chain repertoire (patient L). Both patients were treated with rituximab, an anti-CD20 monoclonal antibody that selectively depletes peripheral CD20+ B-cells for several months. The B-cell repertoire was studied before therapy and at the earliest time point after B-cell regeneration in both patients. A longer follow-up (up to 27 months) was performed in patient H who was treated a second time with rituximab after 17 months. Heavy chain gene analysis was carried out by nested-PCR on bulk DNA from peripheral B-cells using family-specific primers, followed by subcloning and sequencing. During the study, patient H received two courses of antibody treatment. B-cell depletion lasted 7 and 10 months, respectively and each time was accompanied by a clinical improvement. Anti-CD20 therapy induced two types of changes in this patient. During the early phase of B-cell regeneration, we noticed the presence of an expanded and recirculating population of highly mutated B-cells. These cells expressed very different immunoglobulin VH genes compared before therapy. They were class-switched and could be detected for a short period only. The long-term changes were more subtle. Nevertheless, characteristic changes in the VH2 family, as well as in specific mini-genes like VH3-23, 4-34 or 1-69 were noticed. Some of these genes have already been reported to be biased in autoimmune diseases. Also in autoimmune diseases, in particular in RA, clonal B-cells have been frequently found in the repertoire. B-cell depletion with anti-CD20 antibody resulted in a long term loss of clonal B-cells in patient H. Thus, temporary B-cell depletion induced significant changes in the heavy chain repertoire. For the light chain gene analysis, the repertoire changes were analysed separately for naive (CD27-) and memory (CD27+) B-cells. Individual CD19+ B-cells were sorted into CD27- and CD27+ cells and single cell RT-PCR was performed, followed by direct sequencing. During the study, patient L received one course of antibody treatment. B-cell depletion lasted 10 months and the light chain repertoire was studied before and after therapy. Before therapy, some differences in the distribution of VL and JL genes were observed between naive and memory B-cells. In particular, the predominant usage of Jk-proximal Vk genes by the CD27- naive B-cells indicated that the receptor editing was less frequent in this population compared to memory cells. In VlJl rearrangements also, some evidence for decreased receptor editing was noticed, with the overrepresentation of the Jl2/3 gene segments. The CDR3 regions of naive and memory cells showed different characteristics: the activity of the terminal deoxynucleotidyl transferase and exonuclease in Vl(5') side was greater in memory cells. Also in the light chain repertoire, we observed some changes induced by the B-cell depletive therapy. There was a tendency of a less frequent usage of Jk-proximal Vk genes in the naive population. Some Vl genes, previously described in autoimmune diseases and connected to rheumatoid factor activity, such as 3p, 3r, 1g, were not found after therapy. The different characteristics of the CDR3 regions of VlJl rearrangements were not observed anymore. Very significantly, the ratio Vk to Vl was shifted toward a greater usage of Vk genes in the naive population after therapy. Taken together, these results indicate that therapeutic transient B-cell depletion by anti-CD20 antibody therapy modulates the immunoglobulin gene repertoire in the two RA patients studied. Measurable changes were observed in the heavy chain as well as in the light chain repertoire, which may be relevant to the course of the disease. This also supports the notion that the composition of the B-cell repertoire is influenced by the disease and that B-cell depletion can reset biases that are typically found in autoimmune diseases.},
  subject      = {Rheumatoide Arthritis},
  language  = {en}
}
@phdthesis{Grozdanov2004,
  author    = {Grozdanov, Lubomir Assenov},
  title     = {Analysis of the genome organization and fitness traits of non-pathogenic Escherichia coli strain Nissle 1917 (O6:K5:H1)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9304},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {In the last years more than one hundred microbial genomes have been sequenced, many of them from pathogenic bacteria. The availability of this huge amount of sequence data enormously increases our knowledge on the genome structure and plasticity, as well as on the microbial diversity and evolution. In parallel, these data are the basis for the scientific "revolution" in the field of industrial and environmental biotechnology and medical microbiology - diagnostics and therapy, development of new drugs and vaccines against infectious agents. Together with the genomic approach, other molecular biological methods such as PCR, DNA-chip technology, subtractive hybridization, transcriptomics and proteomics are of increasing importance for research on infectious diseases and public health. The aim of this work was to characterize the genome structure and -content of the probiotic Escherichia coli strain Nissle 1917 (O6:K5:H31) and to compare these data with publicly available data on the genomes of different pathogenic and non-pathogenic E. coli strains and other closely related species. A cosmid genomic library of strain Nissle 1917 was screened for clones containing the genetic determinants contributing to the successful survival in and colonization of the human body, as well as to mediate this strain's probiotic effect as part of the intestinal microflora. Four genomic islands (GEI I-IVNissle 1917) were identifed and characterized. They contain many known fitness determinants (mch/mcm, foc, iuc, kps, ybt), as well as novel genes of unknown function, mobile genetic elements or newly identified putative fitness-contributing factors (Sat, Iha, ShiA-homologue, Ag43-homologues). All islands were found to be integrated next to tRNA genes (serX, pheV, argW and asnT, respectively). Their structure and chromosomal localization closely resembles those of analogous islands in the genome of uropathogenic E. coli strain CFT073 (O6:K2(?):H1), but they lack important virulence genes of uropathogenic E. coli (hly, cnf, prf/pap). Evidence for instability of GEI IINissle 1917 was given, since a deletion event in which IS2 elements play a role was detected. This event results in loss of a 30 kb DNA region, containing important fitness determinants (iuc, sat, iha), and therefore probably might influence the colonization capacity of Nissle 1917 strain. In addition, a screening of the sequence context of tRNA-encoding genes in the genome of Nissle 1917 was performed to identify genome wide potential integration sites of "foreign" DNA. As a result, similar "tRNA screening patterns" have been observed for strain Nissle 1917 and for the uropathogenic E. coli O6 strains (UPEC) 536 and CFT073. I. Summary 4 The molecular reason for the semi-rough phenotype and serum sensitivity of strain Nissle 1917 was analyzed. The O6-antigen polymerase-encoding gene wzy was identified, and it was shown that the reason for the semi-rough phenotype is a frame shift mutation in wzy, due to the presence of a premature stop codon. It was shown that the restoration of the O side-chain LPS polymerization by complementation with a functional wzy gene increased serumresistance of strain Nissle 1917. The results of this study show that despite the genome similarity of the E. coli strain Nissle 1917 with the UPEC strain CFT073, the strain Nissle 1917 exhibits a specific set of geno- and phenotypic features which contribute to its probiotic action. By comparison with the available data on the genomics of different species of Enterobacteriaceae, this study contributes to our understanding of the important processes such as horizontal gene transfer, deletions and rearrangements which contribute to genome diversity and -plasticity, and which are driving forces for the evolution of bacterial variants. At last, the fim, bcs and rfaH determinats whose expression contributes to the mutlicellular behaviour and biofilm formation of E. coli strain Nissle 1917 have been characterized.},
  subject      = {Escherichia coli},
  language  = {en}
}
@phdthesis{Henn2004,
  author    = {Henn, Julian},
  title     = {The electron density : a bridge between exact quantum mechanics and fuzzy chemical concepts},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-9003},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {Summary The nature of the chemical bond is a topic under constant debate. What is known about individual molecular properties and functional groups is often taught and rationalized by explaining Lewis structures, which, in turn, make extensive use of the valence concept. The valence concept distinguishes between electrons, which do not participate in chemical interactions (core electrons) and those, which do (single, double, triple bonds, lone-pair electrons, etc.). Additionally, individual electrons are assigned to atomic centers. The valence concept is of paramount success: It allows the successful planning of chemical syntheses and analyses, it explains the behavior of individual functional groups, and, moreover, it provides the "language" to think of and talk about molecular structure and chemical interactions. The resounding success of the valence concept may be misleading to forget its approximative character. On the other hand, quantum mechanics provide in principle a quantitative description of all chemical phenomena, but there is no discrimination between electrons in quantum mechanics. From the quantum mechanical point of view there are only indistinguishable electrons in the field of the nuclei, i.e., it is impossible to assign a given electron to a particular center or to ascribe a particular purpose to individual electrons. The concept of indistinguishability of micro particles is founded on the Heisenberg uncertainty relation, which states, that wavepackets diverge in the 6N dimensional phase space, such that individual trajectories can not be identified. Hence it is a deep-rooted and approved physical concept. As an introduction to the present work density partitioning schemes were discussed, which divide the total molecular density into chemically meaningful areas. These partitioning schemes are intimately related to either the concepts of bound atoms in a molecule (as in the Atoms In Molecules theory (AIM) according to Bader or as in the Hirshfeld partitioning scheme) or to the concept of chemical structure in the sense of Lewis structures, which divide the total molecular density into core and valence density, where the valence density is split up again into bonding and non-bonding electron densities. Examples are early and recent loge theories, the topological analysis by means of the Electron Localization Function (ELF), and the Natural Bond Orbital (NBO) approach. Of these partitioning schemes, the theories according to Bader (AIM), to Becke and Edgecomb (ELF) and according to Weinhold (NBO and Natural Resonance Theory, NRT), respectively, were reviewed in detail critically. Points of criticism were explicated for each of the mentioned theories. Since theoretically derived electron densities are to be compared to experimentally derived densities, a brief introduction into the theory of X-ray di®raction experiments was given and the multipole formalism was introduced. The procedure of density refinement was briefly discussed. Various suggestions for improvements were developed: One strategy would be the employment of model parameters, which are to a maximum degree mutually orthogonal, with the object of minimizing correlations among the model parameters, e.g., to introduce nodal planes into the radial functions of the multipole model. A further suggestion involves the guidance of the iterative refinement procedure by an extremum principle, which states, that when di®erent solutions to the least squares minimization problem are available with about the same statistical measures of quality and with about the same residual density, then the solution is to prefer, which yields a minimum density at the bond critical point (BCP) and a maximum polarity in terms of the ratio of distances between the BCP and the nuclei. This suggestion is based on the well known fact, that the bond polarity (in terms of the ratio of distances between the BCP and the respective nuclei) is underestimated in the experiment. Another suggestion for including physical constraints is the explicit consideration of the virial theorem, e.g., by evaluating the integration of the Laplacian over the entire atomic basins and comparing this value to zero and to the value obtained from the integration of the electron gradient field over the atomic surface. The next suggestion was to explicitly use the electrostatic theorem of Feynman (often also denoted as Hellmann-Feynman theorem), which states, that the forces onto the nuclei can be calculated from the purely classical electrostatic forces of the electron distribution and the nuclei distribution. For a stationary system, these forces must add to zero. This also provides an internal quality criterion of the density model. This can be performed in an iterative way during the refinement procedure or as a test of the final result. The use of the electrostatic theorem is expected to reduce significantly correlations among static density parameters and parameters describing vibrations, since it is a valuable tool to discriminate between physically reasonable and artificial static electron densities. All of these mentioned suggestions can be applied as internal quality criteria. The last suggestion is based on the idea to initiate the experimental refinement with a set of model parameters, which is, as much as possible close to the final solution. This can be achieved by performing periodic boundary conditions calculations, from which theoretically created files are obtained, which contain the Miller indices (h, k, l) and the respective intensity I. This file is used for a model parameter estimation (refinement), which excludes vibrations. The resulting parameters can be used for the experimental refinement, where, in a first step, the density parameters are fixed to determine the parameters describing vibrations. For a fine tuning, again the electrostatic theorem and the other above mentioned suggestions could be applied. Theoretical predictions should not be biased by the method of computation. Therefore the dependence of the density analyzing tools on the level of calculation (method of calculation/basis set) and on the substituents in complex chemical bonding situations were evaluated in the second part of the present work. A number of compounds containing formal single and double sulfur nitrogen bonds was investigated. For these compounds, experimental data were also available. The calculated data were compared internally and with the experimental results. The internal comparison was drawn with regard to questions of convergency as well as with regard to questions of consistency: The resulting molecular properties from NBO/NRT analyses were found to be very stable, when the geometries were optimized at the respective level of theory. This stability is valid for variations in the methods of calculation as well as for variations in the basis set. Only the individual resonance weights of the contributing Natural Lewis Structures differed considerably depending on the level of calculation and depending on the substituents. However, the deviations were in both cases to a large extent within a limit which preserves the descending order of the leading resonance structure weights. The resulting bond orders, i.e., the total, covalent and ionic bond order from NRT calculations, were not affected by the shift in the resonance weights. The analysis of the bond topological parameters resulted in a discrimination between insensitive parameters and sensitive parameters. The stable parameters do neither depend strongly on the method of calculation nor on the basis set. Only minor variation occurs in the numerical values of these parameters, when the level of calculation is changed or even when other functional groups (H, Me, or tBu) are employed, as long as the methods of calculation do not drop considerably below a standard level. The bond descriptors of the sulfur nitrogen bonds were found to be also stable with respect to the functional groups R = H, R = Me, and R = tBu. Stable parameters are the bond distance, the density at the bond critical point (BCP) and the ratio of distances between the BCP and the nuclei A and B, which varies clearly when considering the formal bond type. For very small basis sets like the 3-21G basis set, this characteristic stability collapses. The sensitive parameters are based on the second derivatives of the density with respect to the coordinates. This is in accordance with the well known fact, that the total second derivative of the density with respect to the coordinates is a strongly oscillating function with positive as well as negative values. A profound deviation has to be anticipated as a consequence of strong oscillations. lambda3, which describes the local charge depletion in the direction of the interaction line, is the most varying parameter. A detailed analysis revealed that the position of the BCP in the rampant edge of the Laplacian distribution is responsible for the sensitivity of the numerical value of lambda3 in formal double bonds. Since the slope of the Laplacian assumes very high values in its rampant edge, a tiny displacement of the BCP leads already to a considerable change in lambda3. This instability is not a failure of the underlying theory, but it yields de facto to a considerable dependence of sensitive bond topological properties on the method of calculation and on the applied basis sets. Since the total second derivative is important to judge on the nature of the bond in the AIM theory (closed shell interactions versus shared interactions), the changes in lambda3 can lead to differing chemical interpretations. The comparison of theoretically derived bond topological properties of various sulfur nitrogen bonds provides the possibility to measure the self consistency of this data set. All data sets clearly exhibit a linear correlation between the bond distances and the density at the BCP on one hand and between the bond distances and the Laplacian values at the BCP on the other hand. These correlations were almost independent of the basis set size. In this context, the linear regression has to be regarded exclusively as a descriptive statistics tool. There is no correlation anticipated a priori. The formal bond type was found to be readily deducible from the theoretically obtained bond topological descriptors of the model systems. In this sense, the bond topological properties are self consistent despite of the numerical sensitivity of the derivatives, as exemplified above. Often, calculations are performed with the experimentally derived equilibrium geometries and not with optimized ones. Applying this approach, the computationally costly geometry optimizations are saved. Following this approach the bond topological properties were calculated using very flexible basis sets and employing the fixed experimental geometry (which, of course, includes the application of tBu groups). Regression coe±cients similar to those from optimized geometries were obtained for correlations between bond distances and the densities at the BCP as well as for the correlation between bond distances and the Laplacian at the BCP, i.e. the approach is valid. However, the data points scattered less and the coe±cient of correlation was clearly increased when geometry optimizations were performed beforehand. The comparison between data obtained from theory and experiment revealed fundamental discrepancies: In the data set of bond topological parameters from the experiment, the behavior of only 2 out of 3 insensitive parameters was comparable to the behavior of the theoretically obtained values, i.e. theoretical and experimental bond distances as well as theoretical and experimental densities at the BCP correlate. From the theoretically obtained data it was easy to deduce the formal bond type from the position of the BCP, since it changed in a systematic manner. The respective experimentally obtained values were almost constant and did not change systematically. For the SN bonds containing compounds, the total second derivative assumes exclusively negative values in the experiment. Due to the different internal behavior, experimentally and theoretically sensitive bond topological values could not be compared directly. The qualitative agreement in the Laplacian distribution, however, was excellent. In the third and last part of this work, the application to chemical systems follows. Formal hypervalent molecules, i.e. molecules where some atoms are considered to hold more than 8 electrons in their valence shell, were investigated. These were compounds containing sulfur nitrogen bonds (H(NtBu)2SMe, H2C{S(NtBu)2(NHtBu)}2, S(NtBu)2 and S(NtBu)3) and a highly coordinated silicon compound. The set of sulfur nitrogen compounds also contained a textbook example for valence expansion, the sulfur triimide. For these molecules, experimental reference values were available from high resolution X-ray experiments. The experimental results were in the case of the sulfur triimide not unique. Furthermore, from the experimental bond topological data no definite conclusion about the formal bonding type could be drawn. The situation of sulfur nitrogen bonds in the above mentioned set of molecules was analyzed in terms of a geometry discussion and by means of a topological analysis. The methyl-substituted isolated molecules served as model compounds. For the interpretation of the bonding situation additional NBO/NRT calculations were preformed for the sulfur nitrogen compounds and an ELF calculation and analysis was performed for the silicon compound. The ELF analysis included not only the presentation and discussion of the ELF-isosurfaces (eta = 0.85), but also the investigation of populations of disynaptic valence basins and the percentage contributions to these populations of the individual atoms when the disynaptic valence basins are split into atomic contributions according to Bader's partitioning scheme. The question of chemical interest was whether hypervalency is present in the set of molecules or not. In the first case the octet rule would be violated, in the second case Pauling's verdict would be violated. While the concept of hypervalency is well established in chemistry, the violation of Pauling's verdict is not. The quantitative numbers of the sensitive bond topological values from theory and experiment were not comparable, since no systematic relationship between the experimentally and theoretically determined sensitive bond descriptors was found. However, the insensitive parameters are in good agreement and the qualitative Laplacian distribution is, with few exceptions, in excellent agreement. The formal bonding type was deduced from experimental and theoretical topological data by considering the number and shape of valence shell charge concentrations in proximity to the sulfur and nitrogen centers. The results from NBO/NRT calculations confirmed the findings. All employed density analyzing tools AIM, ELF and NBO/NRT coincided in describing the bonding situation in the formally hypervalent molecules as highly polar. A comparison and analysis of experimentally and theoretically derived electron densities led consistently to the result, that regarding this set of molecules, hypervalency has to be excluded unequivocally.},
  subject      = {Elektronendichtebestimmung},
  language  = {en}
}