Classical Motion in Random Potentials

We consider the motion of a classical particle under the influence of a random potential on R^d, in particular the distribution of asymptotic velocities and the question of ergodicity of time evolution.Comment: 45 pages, 3 figure

A Maturity Model for Assessing Industry 4.0 Readiness and Maturity of Manufacturing Enterprises

AbstractManufacturing enterprises are currently facing substantial challenges with regard to disruptive concepts such as the Internet of Things, Cyber Physical Systems or Cloud-based Manufacturing – also referred to as Industry 4.0. Subsequently, increasing complexity on all firm levels creates uncertainty about respective organizational and technological capabilities and adequate strategies to develop them. In this paper we propose an empirically grounded novel model and its implementation to assess the Industry 4.0 maturity of industrial enterprises in the domain of discrete manufacturing. Our main goal was to extend the dominating technology focus of recently developed models by including organizational aspects. Overall we defined 9 dimensions and assigned 62 items to them for assessing Industry 4.0 maturity. The dimensions “Products”, “Customers”, “Operations” and “Technology” have been created to assess the basic enablers. Additionally, the dimensions “Strategy”, “Leadership”, Governance, “Culture” and “People” allow for including organizational aspects into the assessment. Afterwards, the model has been transformed into a practical tool and tested in several companies whereby one case is presented in the paper. First validations of the model's structure and content show that the model is transparent and easy to use and proved its applicability in real production environments

Optical spectroscopy of strongly correlated electron systems

In this thesis, both time-resolved, nonlinear optical spectroscopy and linear spectroscopy are used to investigate the interactions and dynamics of elementary excitations in strongly correlated electron systems. In the first part, we investigate the renormalization of magnetic elementary excitations in the transition metal oxide Cr{sub 2}O{sub 3}. We have created a non-equilibrium population of antiferromagnetic spin waves and characterized its dynamics, using frequency- and time-resolved optical spectroscopy of the exciton-magnon transition. We observed a time-dependent pump-probe line shape, which results from excitation induced renormalization of the spin wave band structure. We present a model that reproduces the basic characteristics of the data, in which we postulate the optical nonlinearity to be dominated by interactions with long-wavelength spin waves, and the dynamics due to spin wave thermalization. Using linear spectroscopy, coherent third-harmonic generation and pump-probe experiments, we measured the optical properties of the charge-transfer (CT) gap exciton in Sr{sub 2}CuO{sub 2}Cl{sub 2}, an undoped model compound for high-temperature superconductors. A model is developed which explains the pronounced temperature dependence and newly observed Urbach tail in the linear absorption spectrum by a strong, phonon-mediated coupling between the charge-transfer exciton and ligand field excitations of the Cu atoms. The third-order nonlinear optical susceptibility within the Cu-O plane of Sr{sub 2}CuO{sub 2}Cl{sub 2} is fully characterized in both amplitude and phase, and symmetry based conclusions are made with respect to the spatial arrangement of the underlying charge distribution. Theoretical considerations ascribe a newly reported resonance in the third-order nonlinear susceptibility at 0.7 eV to a three-photon transition from the ground state to the charge-transfer exciton. An even parity intermediate state of Cudd character, is found to contribute to the transition. Finally, preliminary results of time-resolved pump-probe spectroscopy confirm that the CT exciton or one of its constituent parts couples strongly to phonons, and we suggest ultrafast thermalization with the lattice as the dominating mechanism underlying the dynamical properties

Entwicklung, Produktion und präklinische Charakterisierung bispezifischer NKG2D Fusionsproteine zur Immunmodulation von NK und T Zellen zur Therapie von malignen hämatopoetischen Neoplasien

Die Immuntherapie hat in den letzten Jahren einen zunehmend höheren Stellenwert für die Behandlung maligner Tumoren eingenommen. Dabei konnten chimärisierte und humanisierte monoklonale Antikörper die Prognose verschiedener maligner Erkrankungen erheblich verbessern. Dennoch weisen heutige anti-Tumor-Antikörper unter anderem bezüglich ihrer immunstimulierenden Aktivität sowie der Antigenbindung Schwächen auf. Ein Ansatz zur Entwicklung neuer, effizienterer Formate ist dabei die Herstellung bispezifischer Antikörper (bsAb), die nach der Bindung an ihr Zielantigen mit ihrem Effektorarm eine gezieltere Immunaktivierung bewirken, da sie spezifische Rezeptoren aktivieren und eine definierte Population an Effektorzellen rekrutieren können. Durch bsAb kann nicht nur der aktivierende CD16 Rezeptor auf NK Zellen spezifisch aktiviert werden, sondern über Stimulation von CD3 auch eine Immunantwort zytotoxischer T Zellen mit ihrem höheren Effektorpotential induziert werden. Um klinisch relevante, effektive, zielgerichtete neuartige Antikörper zu entwickeln, ist die Identifikation möglichst tumorrestringierter Zielstrukturen von großer Bedeutung. Gegenstand dieser Arbeit ist deshalb die Entwicklung, Herstellung und Charakterisierung neuartiger Immunrezeptor Fusionsproteine, welche mit ihrem Immunrezeptoranteil (aus der extrazellulären Domäne von NKG2D) die Zielantigene NKG2D Liganden (NKG2DL) binden. Der Effektorarm der Fusionsproteine besteht aus einem Antikörperfragment, welches entweder gegen CD16 (Aktivierung des FcyIIIA Rezeptors auf NK Zellen) oder gegen CD3 (Stimulation von T Zellen) gerichtet ist. Nach erfolgreicher Produktion und Reinigung beider Fusionsproteine erfolgte zuerst eine Charakterisierung der neuen Proteine. So konnten für beide Konstrukte, NKG2D-CD16 und NKG2D-CD3, eine spezifische Bindung sowohl an die Effektor-Seite sowie an die Ziel-Seite nachgewiesen werden. Für NKG2D-CD16 zeigte sich im Vergleich zu einem bereits in Vorarbeiten entwickelten, monospezifischen Fusionsprotein NKG2D-Fc-ADCC in Titrationsexperimenten eine erhöhte Affinität gegenüber dem Fc-Rezeptor auf NK Zellen. Auch die spezifische Bindung der Konstrukte an ihre jeweilige Effektorpopulation konnte gezeigt werden. In Zytotoxic-Assays wurde für beide Konstrukte die gezielte Lysierung der Zielzellen nachgewiesen. Erste funktionelle Daten belegen somit das Anti-Tumor-Potential der beiden Fusionsproteine, welche ein vielversprechendes Therapeutikum für die Immuntherapie darstellen können

Analysis and extension of a PEMFC model

A stationary, macro-homogeneous 1D through-plane model of a membrane electrode assembly (MEA) has been developed by Vetter and Schumacher [1]. In this work, a sensitivity analysis for various parameters of this MEA model is carried out. 48 parameters are identified that impact the model behaviour through the parameterization of transport properties, electrochemistry and through operating conditions. All parameters have been varied over a decade and compared to the initial value to study the impact on the simulated I-V characteristic. If the variation outranged physically reasonable limits, the latter are applied as variation boundaries. In Fig.1 the variation of the electrical conductivity of the GDL sigma_e is shown as exemplary simulation result. The value is varied between 130 and 1300 S/m to account for data of different products types, e.g. from SGL Carbon [2], Toray [3], Freudenberg [4] and Ballard [5]. Fig.1 (a) depicts the polarisation curve with cell voltage U in V plotted over the current density i in A/cm². Two reference points at static cell voltages of Uref = 0.8 V with iref = 0.3 A/cm² (partial load) and Uref = 0.6 V with iref = 2.3 A/cm² (full load) are used in order to evaluate the specific parameter sensitivity. The colour legend depicts the varied parameter values. It can be seen that a higher electrical conductivity leads to a higher current density at equal cell voltage. In Fig.1 (b), the relative deviation of the current density at static cell voltage CCD = (i-iref)/iref is plotted over the varied parameter range. Passing the 0-line indicates passing the default parameter value. Thus, positive deviation stands for an increase and negative deviation for a decrease in performance. The relative deviation at 0.6 V reaches from -0.1 to 0.2, indicating a high sensitivity of the model to sigma_e at full load operation. For partial load conditions, the influence of sigma_e is lower than at full load, as expected from the domination of activation losses over ohmic losses at low current densities. 1. R. Vetter, J. O. Schumacher. Free open reference implementation of a two-phase PEM fuel cell model. Manuscript in preparation for Computer Physics Communications 2. SIGRACET® Gas Diffusion Layers for PEM Fuel Cells, Electrolyzers and Batteries. White Paper. SGL CARBON GmbH. Aug. 2016. 3. Toray Carbon Fiber Paper TGP-H. Technical Data. Accessed: 12. February 2018. FUEL CELL Store. 4. Freudenberg Gas Diffusion Layers for PEMFC DMFC. Technical Data. Freudenberg. Dec. 2014. 5. AvCarb Gas Diffusion Systems for Fuel Cells. Technical Data. AvCarb. Feb. 2013

Collective variables between large-scale states in turbulent convection

The dynamics in a confined turbulent convection flow is dominated by multiple long-lived macroscopic circulation states that are visited subsequently by the system in a Markov-type hopping process. In the present work, we analyze the short transition paths between these subsequent macroscopic system states by a data-driven learning algorithm that extracts the low-dimensional transition manifold and the related new coordinates, which we term collective variables, in the state space of the complex turbulent flow. We therefore transfer and extend concepts for conformation transitions in stochastic microscopic systems, such as in the dynamics of macromolecules, to a deterministic macroscopic flow. Our analysis is based on long-term direct numerical simulation trajectories of turbulent convection in a closed cubic cell at a Prandtl number Pr=0.7 and Rayleigh numbers Ra=106 and 107 for a time lag of 105 convective free-fall time units. The simulations resolve vortices and plumes of all physically relevant scales, resulting in a state space spanned by more than 3.5 million degrees of freedom. The transition dynamics between the large-scale circulation states can be captured by the transition manifold analysis with only two collective variables, which implies a reduction of the data dimension by a factor of more than a million. Our method demonstrates that cessations and subsequent reversals of the large-scale flow are unlikely in the present setup, and thus it paves the way for the development of efficient reduced-order models of the macroscopic complex nonlinear dynamical system

Collective variables between large-scale states in turbulent convection

The dynamics in a confined turbulent convection flow is dominated by multiple long-lived macroscopic circulation states, which are visited subsequently by the system in a Markov-type hopping process. In the present work, we analyze the short transition paths between these subsequent macroscopic system states by a data-driven learning algorithm that extracts the low-dimensional transition manifold and the related new coordinates, which we term collective variables, in the state space of the complex turbulent flow. We therefore transfer and extend concepts for conformation transitions in stochastic microscopic systems, such as in the dynamics of macromolecules, to a deterministic macroscopic flow. Our analysis is based on long-term direct numerical simulation trajectories of turbulent convection in a closed cubic cell at a Prandtl number $Pr = 0.7$ and Rayleigh numbers $Ra = 10^6$ and $10^7$ for a time lag of $10^5$ convective free-fall time units. The simulations resolve vortices and plumes of all physically relevant scales resulting in a state space spanned by more than 3.5 million degrees of freedom. The transition dynamics between the large-scale circulation states can be captured by the transition manifold analysis with only two collective variables which implies a reduction of the data dimension by a factor of more than a million. Our method demonstrates that cessations and subsequent reversals of the large-scale flow are unlikely in the present setup and thus paves the way to the development of efficient reduced-order models of the macroscopic complex nonlinear dynamical system.Comment: 24 pages, 12 Figures, 1 tabl

Proposal to add medievalist characters to the UCS

This is a proposal to add several Latin characters to the international character encoding standard Unicode. These additions were published in Unicode Standard version 5.1 in March 2008. This proposal includes characters that occur in medieval European philology and linguistics. Some changes were made after the proposal was written, so users should consult the latest Unicode code charts for the most up-to-date repertoire, accessible from: