Thermal Fluctuations of Biomolecules : An Approach to Understand Subdiffusion in the Internal Dynamics of Peptides and Proteins

Auf der Basis von Molekulardynamik-Simulationen werden die thermischen Fluktuationen in den inneren Freiheitsgraden von Biomolekülen, wie Oligopeptiden oder einer Beta-Schleife, untersucht, unter besonderer Beachtung der zeitgemittelten, mittleren quadratischen Verschiebung (MSD). Die Simulationen lassen in einem Bereich von Pikosekunden bis einige zehn Nanosekunden Subdiffusion im thermischen Gleichgewicht erkennen. Mögliche Modelle subdiffusiver Fluktuationen werden vorgestellt und diskutiert. Der zeitkontinuierliche Zufallslauf (CTRW), dessen Wartezeitenverteilung einem Potenzgesetz folgt, wird als mögliches Modell untersucht. Während das ensemble-gemittelte MSD eines freien CTRW Subdiffusion zeigt, ist dies beim zeitgemittelten MSD nicht der Fall. Hier wird gezeigt, dass der CTRW in einem begrenzten Volumen ein zeitgemitteltes MSD aufweist, das ab einer kritischen Zeit subdiffusiv ist. Eine analytische Näherung des zeitgemittelten MSD wird hergeleitet und mit Computersimulationen von CTRW-Prozessen verglichen. Ein Vergleich der Parameter des begrenzten CTRW mit den Ergebnissen der Molekulardynamik-Simulationen zeigt, dass CTRW die Subdiffusion der inneren Freiheitgrade nicht erklären kann. Eher muss die Subdiffusion als Konsequenz der fraktalartigen Struktur des zugänglichen Volumens im Konfigurationsraum betrachtet werden. Mit Hilfe von Übergangsmatrizen kann der Konfigurationsraum durch ein Netzwerkmodell angenähert werden. Die Hausdorff-Dimension der Netzwerke liegt im fraktalen Bereich. Die Netzwerkmodelle erlauben eine gute Modellierung der Kinetik auf Zeitskalen ab 100 ps

Single particle tracking in systems showing anomalous diffusion: the role of weak ergodicity breaking

Anomalous diffusion has been widely observed by single particle tracking microscopy in complex systems such as biological cells. The resulting time series are usually evaluated in terms of time averages. Often anomalous diffusion is connected with non-ergodic behaviour. In such cases the time averages remain random variables and hence irreproducible. Here we present a detailed analysis of the time averaged mean squared displacement for systems governed by anomalous diffusion, considering both unconfined and restricted (corralled) motion. We discuss the behaviour of the time averaged mean squared displacement for two prominent stochastic processes, namely, continuous time random walks and fractional Brownian motion. We also study the distribution of the time averaged mean squared displacement around its ensemble mean, and show that this distribution preserves typical process characteristic even for short time series. Recently, velocity correlation functions were suggested to distinguish between these processes. We here present analytucal expressions for the velocity correlation functions. Knowledge of the results presented here are expected to be relevant for the correct interpretation of single particle trajectory data in complex systems.Comment: 15 pages, 15 figures; References adde

Énoncés métalangagiers en contraste :

Cet article se propose d’étudier le discours puriste sur la langue française dans une perspective comparative par l’opposition de deux genres d’interactionnisme discursif. Partant d’un aperçu sur la tradition métalinguistique en France et sur la notion d’aménagement linguistique, nous nous consacrons d’abord aux recherches liées au programme de la linguistique populaire. Dans ce contexte, notre contribution essaie tout d’abord de situer les acteurs du discours puriste et leurs actions verbales sur un axe qui oppose les constructions savantes aux constructions ‘populaires’. Dans le but de définir les lieux communs idéologiques véhiculés dans les énoncés des acteurs puristes, s’exprimant dans des lieux et par des genres de communication différents, les approches de l’analyse de discours (AD) nous serviront de cadre méthodologique. Dans cette optique, l’analyse s’intéresse principalement aux topoï structurant le discours puriste, dans lequel savoirs et représentations méta­linguistiques spécifiques et récurrents constituent un inventaire de réflexions partagées par les puristes.This article considers the purist discourse of French language from a comparative perspective by analyzing the opposition of two discursive genres of metalinguistic interaction. Firstly, the article will be introduced by a discussion of the metalinguistic discourse tradition in France and the field of language planning. Secondly, the folk linguistic research and its interests will be illustrated. Considering the verbalized forms of cognitive representations in linguistic discourse, the focus will be on defining the actor’s opinion of the continuum between an expert and a layperson. The ideologically constructed commonplaces conveyed by purist actors using different communication areas and genres lead to the introduction of discourse linguistics as an appropriate approach within the field of Applied Linguistics. Following this theoretical background, the objective of this paper is to reveal specific topical structures and argumentative layouts in order to gain new insights into the underlying beliefs of purism

Inhomogenous risk exposure in dual insurance system: selection effects in Germany’s long-term care plans

Gefördert im Rahmen des Projekts DEALPublished Versio

Zur Methodenkombination in angewandten diskurslinguistischen Untersuchungen: Ein Beitrag aus Perspektive der romanischen Sprachwissenschaft

Der Beitrag befasst sich mit dem Potenzial der Kombination qualitativer und quantitativer Analyseverfahren in diskurslinguistischen Forschungsarbeiten bei der Arbeit mit sprachvergleichenden Korpora. Ausgehend von den Zielen und Forschungsdesideraten der romanistischen Linguistik versteht sich der Beitrag als Plädoyer für eine disziplinen- und fächerübergreifende Diskurslinguistik sowie die Entwicklung eines forschungsgegenstandsangemessenen Methodenbewusstseins

Socioeconomic Burden of Pulmonary Embolism in Europe: Shifting Priorities and Challenges for Novel Reperfusion Strategies

In-hospital case fatality related to acute pulmonary embolism (PE) has been falling since the beginning of this century. However, annual incidence rates continue to climb, and an increasing number of PE survivors need long-term follow-up, chronic anticoagulation treatment, and readmission(s) to the hospital. In European countries, median reimbursed hospital costs for acute PE are still moderate compared with the United States but can increase several-fold in patients with comorbidities and those necessitating potentially life-saving reperfusion treatment. The use of catheter-directed treatment (CDT) has constantly increased in the United States since the past decade, and it has now entered a rapid growth phase in Europe as well, estimated to reach an annual penetration rate of up to 31% among patients with intermediate-high- or high-risk PE by 2030. Ongoing randomised controlled trials are currently investigating the clinical efficacy and safety of these devices. In addition, they will deliver data permitting calculation of their cost-effectiveness in different health care reimbursement systems, by revealing the extent to which they can reduce complications and consequently the need for intensive care and the overall length of hospital stay. After discharge, key cost drivers are related to chronic cardiopulmonary diseases (other than PE itself) leading to frequent readmissions, persistent symptoms, and functional limitations which result in poor quality of life, productivity loss, and substantial indirect costs. Implementation of structured outpatient programmes with a holistic approach to post-PE care, targeting overall cardiovascular health and the patient's well-being, bears the potential to cost-effectively reduce the overall socioeconomic burden of PE

3D Image Based Structural Analysis of Leather for Macroscopic Structure- Property Simulation

Content: The intrinsic structure significantly influences the mechanical properties of leather. In consequence, knowledge of leather’s hierarchical structure is essential in order to find the most suited leather for specific application. Leather structure based parameters are of major importance for both manufacturing and leather processing industries. In this respect, intensive structure investigations have been subjected in continuous research work. Quantitative image analysis combined with stochastic micro-structure modelling and numerical simulation of macroscopic properties is a promising approach to gain a deeper understanding of complex relations between material’s micro-structure geometry and macroscopic properties. Key ingredient is a reliable geometric description provided by the quantitative analysis of 3D images of the material micro-structures. For leather, both imaging and image analysis are particularly challenging, due to the multi-scale nature of the leather’s micro-structure. Scales in leather are not well separated. Previously, high resolution computed tomography allowed 3D imaging of purely vegetable tanned leather samples at micro- and submicro- scale. Segmentation of leather structure as well as of typical structural elements in resulting image data is however hampered by a strong heterogeneity caused by lower scale structural information. The first method for automatic segmentation of typical structural elements at varying scales combined morphological smoothing with defining and iteratively coarsening regions using the waterfall algorithm on local orientations. It yields a hierarchical segmentation of the leather into coarse and fine structural elements that can be used to analyze and compare the structure of leather samples. Size and shape of the structural elements as well as their sub-structure yield information, e. g. on undulation, branching, thickness, cross-sectional shape, and preferred directions. In order to compare the micro-structure of leather samples from various body parts or even species, the segmentation has to be applicable without extensive pre-processing and parameter tuning. Robustness can be gained by applying smoothing methods that are adapted to the goal of defining image regions by similar local orientation. The challenge is that the space of fiber orientations in 3D is not equipped with an order. Motivated by a recent approach for nevertheless defining erosion and dilation on the sphere, we suggest new definitions for these morphological base transformations on the space of directions in 3D. We present segmentation results for 3D images of leather samples derived by these new morphological smoothing methods. Take-Away: The intrinsic structure significantly influences the mechanical properties of leather. Leather’s hierarchical structure can be analyzed by quantitative 3D image analysis combined with stochastic micro-structure modelling. Segmentation results for 3D images of leather samples derived by new morphological smoothing methods