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Crafting digital doubles: Enhancing shape acquisition and material representation
The demand for digital applications follows the unhindered growth of the digitization of tasks across many fields, including the entertainment industry, education and science but also work environments. ...
Underwater flight in sea turtles and plesiosaurs: Dissection, muscle reconstructions, analog models, and finite element structure analyses inform on flipper twisting and muscle forces in plesiosaurs
This dissertation contributes to our understanding of plesiosaur locomotion by providing foreflipper and hindflipper muscle reconstructions and studying aspects of their muscle physiology (functions, forces, muscle length changes) in comparison to recent sea turtles. This was accomplished by a transdisciplinary biomechanical approach combining knowledge and methods from engineering sciences, comparative anatomy, and paleontology. Plesiosauria belong to a group of extinct reptiles, the Sauropterygia, that adapted to a life in the sea. Plesiosaurs evolved in the Late Triassic and died out at the K/Pg boundary. They are characterized by the increasingly evolving disparity in body form, i.e., either pliosauromorph (large head, short neck) or plesiosauromorph (small head, long neck). Contrastingly, the locomotory apparatus, a fusiform body with a relatively reduced tail and four hydrofoil flippers, experiences little change during over 135 Ma of plesiosaur evolution. So, once the locomotory apparatus of plesiosaurs had evolved, it must have been highly efficient. <br /> In <strong>Chapter 1</strong> flipper osteology and the mode of locomotion of Nothosauria and Plesiosauria are assessed in comparison to recent sea turtles. Plesiosaur locomotion has been disputed for over a century. It has been proposed that plesiosaurs were underwater fliers like penguins and sea turtles, or rowers like e.g., otters, or employing a mixture of both locomotory styles, like sea lions. How the four flippers are coordinated is also still debated. Sea turtles fly underwater. Nonetheless, sea turtles are capable of various rowing motions and even crawling on land. The review concludes that especially joint anatomy and mobilities have largely remained unstudied in all three taxa. Further, osteological evidence mostly corroborates that plesiosaurs were underwater fliers like extant sea turtles while nothosaurs swam partially by tail undulation supported by the foreflippers. <br /> In <strong>Chapter 2</strong> the array of methods (building an analog model of humerus musculature, obtain muscle courses and muscle functions geometrically, pairing up agonistic and antagonistic muscles, finite element structure analysis (FESA) of the humerus) to study underwater flight in plesiosaurs is tested on a recent underwater flying reptile taxon, the sea turtles. This is because for sea turtles muscle attachments and courses can be confirmed by dissection in contrast to the fossil plesiosaurs. To conclude, operating muscle forces during foreflipper up- and downstroke were calculated that show that the downstroke provides more propulsion than the upstroke. Further, the humerus is mostly loaded by compression due to a complex interplay of agonistic and antagonistic muscles and muscle wrappings. This is confirmed by a close match of the compressive stress distribution with the humerus microstructure. <br /> In <strong>Chapter 3</strong> fore- and hindflipper muscles are reconstructed with the extant phylogenetic bracket for the plesiosaur Cryptoclidus eurymerus (IGPB R 324). Additionally, plesiosaur muscle reconstructions are matched with eventually functionally analogous sea turtles, penguins, sea lions, and whales. It turns out that plesiosaurs had complex muscular systems in their fore- and hindflippers that allowed them to twist their flippers along the respective length axis, a feature which has been proven to be crucial for underwater flight by hydrodynamic studies. <br /> In <strong>Chapter 4</strong> Cryptoclidus (IGPB R 324) humerus and femur FESA was computed comparable to Chapter 2. Muscle forces support that the downstroke in plesiosaurs contributed more to propulsion than the upstroke. Further, extensors and flexors that originate from humerus and femur have very high muscle forces corroborating the myological flipper length axis twisting mechanism proposed in chapter 3 and proving its importance for plesiosaur locomotion. <br /> In <strong>Chapter 5</strong> a preliminary FESA of a sea turtle femur, that is part of a rowing and not underwater flying appendage, is presented. The highest muscle forces are obtained for femur pro- and retractors. This highlights that with FESA it is possible to determine differences between limb bones that are employed in different locomotory styles. <br /> <strong>Chapter 6</strong> concludes with a summary of the results of this dissertation placing muscle functions in the context of sauropsid muscle functions and by comparing results for sea turtle and plesiosaur FESA point by point. There are considerable similarities between both underwater flying reptile taxa but also profound differences which highlight the convergently evolved different locomotory muscuskeletal systems but also how similar selective pressures lead to similar adaptations and morphologies....
Evolution of floral organisation and architecture in Boraginales and Geraniales
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Measurement of the double polarization observables G and E in neutral and positive pion photoproduction off the proton
The nucleons, as one of the most fundamental building blocks of visible matter, are built up of quarks and gluons. However, the interactions and dynamics inside the nucleons, which are mediated by the strong force and described by Quantum Chromodynamics (QCD), are still a major challenge to modern physics. In the mass region of the excited states of the nucleons, known as resonances, perturbative calculations are not feasible in QCD, and thus phenomenological approaches and numerical methods are essential for the description of the strong interaction. From the experimental side, complementary probes are available to study the excitation spectrum of the nucleon and different sensitivities to unique observables provide stringent tests of the available theoretical approaches. In the past, most resonances have been found in pion-nucleon scattering experiments. However, the meson photoproduction reactions gained more attention during the last decades since several resonances might only weakly couple to the pion-induced reactions. Although over the years a lot of experimental effort from several collaborations at various accelerator facilities was conducted, discrepancies between theoretical models and experimental results are still present, e.g., regarding the number of resonances. From the experimental point of view, the short lifetimes of the resonances are a possible explanation for these discrepancies. They lead to many broad and overlapping resonances that even contribute selectively to distinct decay channels. The measurement of the total unpolarized cross sections alone is not able to identify all resonances since they are only sensitive to the dominant contributing resonances. For the identification of all resonances and their properties, an unambiguous Partial Wave Analysis (PWA) solution needs to be obtained. This requires precise knowledge of several well-chosen single and double polarization observables in different decay channels. Therefore, current experiments measure these polarization observables that are sensitive to weakly contributing resonances. They can be accessed by either polarizing the initial state, by measuring the polarization of the recoiling nucleon in the final state, or even both.<br /> One experiment, which can measure polarization observables through the meson photoproduction process, is the Crystal Ball experiment within the A2 collaboration. It is located at the electron accelerator MAMI in Mainz, Germany. The G/E measurements made use of elliptically polarized photons that have a linearly and circularly polarized component at the same time. They are produced by the interaction of a longitudinally polarized electron beam with a diamond radiator. In combination with a longitudinally polarized butanol target, the elliptically polarized photons are used to obtain for the first time the double polarization observables G and E simultaneously in one experimental run. Whereas for the determination of E the circular polarization component is needed, the linear polarization component of the photon beam allows to access G with the same experiment.<br /> The double polarization observable G was determined for the reactions γp→pπ<sup>0</sup> and γp→nπ<sup>+</sup> in a beam photon energy range from 230 MeV to 840 MeV (W = 1145 MeV - 1569 MeV) with a full angular coverage. In addition, the double polarization observable E was extracted in the same beam photon energy range for the γp→nπ<sup>+</sup> reaction. Background contamination could be effectively reduced and the desired reaction channels were clearly identified. Asymmetries in the selected azimuthal angular distribution of the final state meson were used to extract the double polarization observable G. For the extraction, two methods were used, namely a χ<sup>2</sup>-fit to the binned event yield asymmetries and an unbinned maximum likelihood fit. The double polarization observable E was determined via the carbon subtraction method.<br /> The results for the double polarization observable G in both analyzed channels provide the first precise measurement in the first resonance region and parts of the second resonance region. Furthermore, the new A2 data in the pπ<sup>0</sup> channel close the gap between the region of the Δ(1232)3/2<sup>+</sup>(P<sub>33</sub>) resonance and the already existing data in the second resonance region. Both data sets are in good agreement with each other in the overlapping region. Furthermore, the high sensitivity of the double polarization observable G to weakly contributing resonances in combination with the new precise data reveal even contributions of partial waves with angular momentum up to l=4 (G-waves) in the first resonance region. In the future, the measurement of both channels will allow an isospin separation of the partial waves and might help, in particular, to improve the uncertainties of the partial wave P<sub>11</sub> to which the Roper resonance N(1440)1/2<sup>+</sup>(P<sub>11</sub>) couples.<br />For the double polarization observable E in the nπ<sup>+</sup> channel, a very good agreement between the measurements with elliptically and circularly polarized photons was observed. Therefore, the results of this work give experimental evidence that an elliptically polarized photon beam can be used to extract the double polarization observable E. In comparison to the existing data, the new A2 data provide additional points in the backward direction of the charged pion and for beam photon energies below 350 MeV. In the overlapping regions, the data sets agree very well with each other.<br />Overall, the results of the polarization observables still show notable differences to recent PWA models. Therefore, the new data will help to further constraint the different models.<br />...
Characterization of the functional role of the Cystein-rich with EGF-like domains (Creld) protein in mitochondrial quality control in Drosophila melanogaster
Cystein-rich with EGF-like domains (Creld) proteins belong to a protein family conserved between species. The mammalian genome contains two Creld genes. Unraveling the function of mammalian Creld proteins has been tried ...
EBI2 is a negative modulator of adipose tissue activity
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Domain-Based Local Pair Natural Orbital Second-Order Møller-Plesset Perturbation Theory, and the Development of its Analytical Gradient
Dynamic electron correlation methods are known to have a computational cost that scales with a high power of the system size: for example, O(N<sup>5</sup>) for second-order Møller-Plesset perturbation theory (MP2), and O(N<sup>7</sup>) for coupled cluster with single, double and perturbative triple excitations (CCSD(T)). Domain-based local pair natural orbital (DLPNO) methods reduce this scaling, while maintaining a modest prefactor, using several approximations: most critically by expanding the virtual space in truncated sets of pair natural orbitals (PNOs), which are combined with the domain approximation and orbital pair screening. <br /> The first part of this work consists of the implementation of MP2 in the DLPNO framework, drawing closely upon the previously existing DLPNO-CCSD method. Several improvements were introduced in the process: (1) The transformation routine for one-external three-index integrals was replaced with a formally linear scaling algorithm, which treats sparsity relationships in a systematic framework. (2) A new domain selection criterion was introduced based on the differential overlap integral between occupied localised orbitals and redundant projected atomic orbitals. (3) An improved, more accurate procedure to screen orbital pairs was developed. DLPNO-MP2 was confirmed to reproduce energy differences computed with the canonical resolution of the identity (RI-)MP2 method to within chemical accuracy, and its performance was demonstrated in large-scale calculations. A simple unrestricted variant of DLPNO-MP2 was implemented for open-shell calculations. <br /> The second and major part of this thesis is the development of the analytical gradient for the closed-shell DLPNO-MP2 method. Importantly, the exact derivative of the entire energy was taken. Mathematical contributions to account for the relaxation of PNOs were described for the first time in the context of local correlation methods. Calculations of electric field gradients with exact and approximate derivatives emphasise the importance of the individual contributions. Additionally, a procedure was introduced to circumvent singularities in the coupled-perturbed localisation equations, which are caused by continuously degenerate localised orbitals. <br /> Extensively testing the DLPNO-MP2 gradient in geometry optimisations showed that it reproduces covalent RI-MP2 bond lengths to well within 0.1 pm. Errors in interatomic distances between non-covalently interacting system parts do not exceed 1 % with default thresholds and 0.3 % with tight thresholds. The DLPNO-MP2 gradient becomes substantially more efficient than the RI-MP2 gradient beyond ca. 70 atoms, while a similar computational effort is incurred in smaller applications. Among the most demanding calculations demonstrated in this work were the geometry optimisation of a host-guest complex containing 205 atoms and more than 4000 basis functions, and a single-point gradient calculation for crambin with 644 atoms and over 12 000 basis functions. Spin-component scaling and double-hybrid density functionals are supported by the implementation....
Stellar populations in gravitationally bound systems
The understanding of how, which, where and when stars form provides important information for the vast majority of astronomical fields. Star-formation has a complex multi-scale physical nature. Stars form in dense sub-parsec ...
Uniform Boundedness of Pole Order of General Eisenstein Series
This work consists of two parts. In the first part we give a general introduction to the chapter 7 of [L1], and settle down some bases needed for the second chapter in which we prove that the order of the poles of a residual ...
Functional impact of Kir4.1 channels in hippocampal NG2 glia on neuronal plasticity and behavior
NG2 glia represents the 4th type of CNS glial cells. In white matter, most of them differentiate into myelinating oligodendrocytes but in grey matter a majority retains their NG2 phenotype throughout life. Intriguingly, ...