The diffractive open charm production is studied using data from 2006-2007, when the leading proton measurement by H1 Very Forward Proton Spectrometer was provided. The charm production is tagged by the decay products of D∗ meson. The cross section of e+ p → e+ D∗ X p in photoproduction regime defined by the value of virtuality Q2 < 2 GeV is determined and corrected for the detector effects. The diffractive D∗ meson photoproduction cross section is compared with the hadron level MC Rapgap prediction based on diffractive parton distribution functions extracted from inclusive ep DIS measurements. Measurement of leading proton provides a unique opportunity to investigate the response of forward detectors for the diffractive events. Using such events, the performance of the large rapidity gap selection is examined.

I use an integrated approach of experiments, theory, and numerical evaluations to show that stiffening and softening/fluidization are natural consequences of the assumption that the cytoskeleton is mechanically essentially equivalent to a transiently crosslinked biopolymer network. I perform experiments on in vitro reconstituted actin/HMM networks and show that already these simple, inanimate systems display fludization and shake-down, but at the same time stress stiffening. Based on the well-established Wlc theory, I then develop a semi-phenomenological mean-field model of a transiently crosslinked biopolymer network, which I call the inelastic glassy wormlike chain (inelastic Gwlc). At the heart of the model is the nonlinear interplay between viscoelastic single-polymer stiffening and inelastic softening by bond breaking. The model predictions are in good agreement with the actin/HMM experiments. Despite of its simplicity, the inelastic Gwlc model displays a rich phenomenology. It reproduces the hallmarks of the mechanics of adherent cells such as power-law rheology, stress and strain stiffening, kinematic hardening, shake-down, fludization, and recovery. The model also may also be able to provide considerable theoretical insights into the underlying physics. For example, using the inelastic Gwlc model, I am able to resolve the apparent paradox between cell softening and stiffening in terms of a parameter-dependent competition of antagonistic nonlinear microscopic mechanisms. I further shed light on the mechanism responsible for fluidization. I identify pertinent parameters characterizing the microstructure and give criteria for the relevance of various effects, including the effect of catch-bonds on the network response. Finally, a way to incorporate irreversible plastic flow is proposed.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20161号 / 理博第4246号 / 新制||理||1611(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 高橋 義朗, 教授 田中 耕一郎, 教授 川上 則雄 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20906号 / 理博第4358号 / 新制||理||1625(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)講師 村上 哲也, 教授 永江 知文, 教授 鶴 剛 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

A theoretical framework for calculating electron transport through molecular junctions is presented. It is based on scattering theory using a Green's function formalism. The model can take both elastic and inelastic scattering into account and treats chemical and physical bonds on equal footing. It is shown that it is quite reliable with respect to the choice of functional and basis set. Applications concerning both elastic and inelastic transport are presented, though the emphasis is on the inelastic transport properties. The elastic scattering application part is divided in two part. The first part demonstrates how the current magnitude is strongly related to the junction width, which provides an explanation why experimentalists get two orders of magnitude differences when performing measurements on the same type of system. The second part is devoted to a study of how hydrogenbonding affects the current-voltage (I-V) characteristics. It is shown that for a conjugated molecule with functional groups, the effects can be quite dramatic. This shows the importance of taking possible intermolecular interactions into account when evaluating and comparing experimental data. The inelastic scattering part is devoted to get accurate predictions of inelastic electron tunneling spectroscopy (IETS) experiments. The emphasis has been on elucidating the importance of various bonding conditions for the IETS. It is shown that the IETS is very sensitive to the shape of the electrodes and it can also be used to discriminate between different intramolecular conformations. Temperature dependence is nicely reproduced. The junction width is shown to be of importance and comparisons between experiment as well as other theoretical predictions are made. / QC 20101118

<p>  </p> <p>The smashing mantis shrimp is a crustacean that uses its dactyl club to defend itself or prey on other animals. This dactyl club is so strong that it can reach accelerations as high as a bullet of a caliber 0.22 gun and impact without breaking. We seek to understand the secrets behind the staggering properties of this club that withstand several high-damage impacts without breaking catastrophically. The dactyl club comprises three parts: the impact region, the periodic region, and the striated region.</p> <p>The first region of interest is the periodic region. This region is made of a helicoidal arrangement of fibers called Bouligand architecture, and in this architecture, cracks only form in the matrix between fibers. The first research project approximates the Bouligand composite with a single helicoidal crack embedded in an isotropic material. The test consists of a disk with a notch under quasistatic biaxial boundary conditions. We found an enhancement of mechanical properties when we increase the pitch angle.</p> <p>In the following section, a coarse-grained model is developed. This model allows multiple crack formation. This approximation tells us that as the initial crack grows, the driving force of crack propagation, the energy release rate, diminishes. The crack stops growing, confining itself, and allowing multiple crack nucleation and delocalization. At the same time, this dissipates more energy as more cracked surfaces appear.</p> <p>Hashin damage model with a cohesive zone model are used under different boundary conditions, geometries, and material properties, to model Bouligand composites. The helicoidal composites outperform the reference ones in peak load and absorbed energy.</p> <p>The next part of this thesis investigates the bicontinuous particles present in the impact surface of the dactyl club. These bicontinuous particles consist of a soft phase (organic) and a hard phase (hydroxyapatite) that can withstand high strain rates. Their stiffness and strength increase with strain rate. On the other hand, preliminary studies suggest that they perform well in cyclic loading.</p> <p>Finally, we proceed to use the helicoidal composites to design structural parts. We introduce a model for simulating the fiber-reinforced composites called LARC05. We verify, validate, and then use models for fiber-reinforced composites.</p>

<p> A research programme is presented to more fully understand the behaviour of Round Hollow Structural Sections subjected to inelastic strain reversals. An attempt is made to establish a preliminary guideline for choosing a reasonable value for the slenderness ratio (D/t) that qualifies the Round HSS for cyclic loading. </p> <p> An experimental programme on nine sections was performed to evaluate the loss in load capacity due to inelastic cyclic loading and to construct the load-deflection hysteresis loops. </p> <p> Three different limiting cyclic deflections were imposed to the smallest D/t section and a comparison was made between the performance of the tube in each case. </p> <p> Prasad's computer program was used to select the strain value at which local buckling will appear and to calculate the half buckle wave-length. The results were compared to the experimental results obtained by the author. </p> <p> A comparison is made between two Round HSS having different diameters and thicknesses but the same D/t ratio. </p> <p> A comparison is made between the behaviour of Round HSS and Square HSS subjected to the same cyclic loading programme. </p> <p> An attempt is made to suggest a reasonable curve relating the number of cycles to failure and the D/t ratio. </p> / Thesis / Master of Engineering (ME)

The theoretical and experimental investigations presented in this thesis are primarily related to the dynamic response of inelastic multi-storey building frames subjected to strong ground motions. The main purpose is to investigate, both analytically and experimentally, those aspects of the dynamic response characteristics which are of importance in aseismic design. In the first part of the thesis, the various parameters pertaining to the structural system are varied in a systematic manner and an assessment is made of the influence of this variation on the maximum response characteristics of the dynamic system. The second part of the thesis consists of an experimental investigation into the inelastic dynamic response of multi-storey frames. The comparison of experimentally obtained inelastic response and that predicted theoretically indicated a good agreement between the two. / Thesis / Doctor of Philosophy (PhD)

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