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Search Results: 1 - 10 of 32034 matches for " Thomas Herrmann "
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Evaluation Blockpraktika Allgemeinmedizin []
Lipkow, Thilo,Lichte, Thomas,Herrmann, Markus
GMS Zeitschrift für Medizinische Ausbildung , 2007,
Simulation of particle mixing in turbulent channel flow due to intrinsic fluid velocity fluctuation
Thomas Burgener,Dirk Kadau,Hans J. Herrmann
Physics , 2010, DOI: 10.1103/PhysRevE.83.066301
Abstract: We combine a DEM simulation with a stochastic process to model the movement of spherical particles in a turbulent channel flow. With this model we investigate the mixing properties of two species of particles flowing through the channel. We find a linear increase of the mixing zone with the length of the pipe. Flows at different Reynolds number are studied. Below a critical Reynolds number at the Taylor microscale of around $R_{c} \approx 300$ the mixing rate is strongly dependent on the Reynolds number. Above $R_{c}$ the mixing rate stays nearly constant.
Critical Parameters in Particle Swarm Optimisation
J. Michael Herrmann,Adam Erskine,Thomas Joyce
Computer Science , 2015,
Abstract: Particle swarm optimisation is a metaheuristic algorithm which finds reasonable solutions in a wide range of applied problems if suitable parameters are used. We study the properties of the algorithm in the framework of random dynamical systems which, due to the quasi-linear swarm dynamics, yields analytical results for the stability properties of the particles. Such considerations predict a relationship between the parameters of the algorithm that marks the edge between convergent and divergent behaviours. Comparison with simulations indicates that the algorithm performs best near this margin of instability.
SSELab: A Plug-In-Based Framework for Web-Based Project Portals
Christoph Herrmann,Thomas Kurpick,Bernhard Rumpe
Computer Science , 2014,
Abstract: Tools are an essential part of every software engineering project. But the number of tools that are used in all phases of the software development life-cycle and their complexity is growing continually. Consequently, the setup and maintenance of current tool chains and development environments requires much effort and consumes a lot of time. One approach to counter this, is to employ web-based systems for development tasks, because centralized systems simplify the administration and the deployment of new features. But desktop IDEs play an important role in software development projects today, and will not be replaced entirely by web-based environments in the near future. Therefore, supporting a mixture of hosted tools and tools integrated into desktop IDEs is a sensible approach. In this paper, we present the SSELab, a framework for web- based project portals that attempts to migrate more software development tools from desktop to server environments, but still allows their integration into modern desktop IDEs. It supports the deployment of tools as hosted services using plug-in systems on the server-side. Additionally, it provides access to these tools by a set of clients that can be used in different contexts, either from the command line, from within IDEs such as Eclipse, or from web pages. In the paper, we discuss the architecture and the extensibility of the SSELab framework. Furthermore, we share our experiences with creating an instance of the framework and integrating various tools for our own software development projects.
Characterization of a New Mouse Model for Peripheral T Cell Lymphoma in Humans
Niklas Beyersdorf, Sandra Werner, Nelli Wolf, Thomas Herrmann, Thomas Kerkau
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0028546
Abstract: Peripheral T cell lymphomas (PTCLs) are associated with a poor prognosis due to often advanced disease at the time of diagnosis and due to a lack of efficient therapeutic options. Therefore, appropriate animal models of PTCL are vital to improve clinical management of this disease. Here, we describe a monoclonal CD8+ CD4? αβ T cell receptor Vβ2+ CD28+ T cell lymphoma line, termed T8-28. T8-28 cells were isolated from an un-manipulated adult BALB/c mouse housed under standard pathogen-free conditions. T8-28 cells induced terminal malignancy upon adoptive transfer into syngeneic BALB/c mice. Despite intracellular expression of the cytotoxic T cell differentiation marker granzyme B, T8-28 cells appeared to be defective with respect to cytotoxic activity as read-out in vitro. Among the protocols tested, only addition of interleukin 2 in vitro could partially compensate for the in vivo micro-milieu in promoting growth of the T8-28 lymphoma cells.
The Economic Challenges of Population Aging in Emerging Markets  [PDF]
Michael Herrmann
Modern Economy (ME) , 2014, DOI: 10.4236/me.2014.52018

Why do studies that examine population aging always come to the same conclusions? Regardless of whether these studies focus on Japan or Germany, Northern Europe or Southern Europe, the developed economies or emerging market economies, they typically suggest that countries will confront a labor shortage which undermines economic growth and that they will confront rising pension and health care costs which call for reduced health care and pension benefits. Are uniform policy recommendations justified because these countries are in fact so similar, or are they rather the result of an undifferentiated and partial analysis? This paper argues that they are the result of a household-focused analysis which fails to take into consideration the very different macroeconomic realities of different countries. From a macroeconomic perspective, this paper examines the broader economic background of emerging markets to understand whether population aging has negative effects on their economic development on the one side, and whether their economic development can cater to an increasing number of old-age dependents on the other.

The Challenge of Sustainable Development and the Imperative of Green and Inclusive Economic Growth  [PDF]
Michael Herrmann
Modern Economy (ME) , 2014, DOI: 10.4236/me.2014.52013

The greatest challenge of the century is to meet the needs of current and future generations, of a large and growing world population, while at the same time ensuring the sustainability of the natural environment. The current development model places unsustainable pressures on the natural resources—forests, land, water and the atmosphere—and causes an increasing frequency and intensity of natural and humanitarian disasters. The paper agrees with increasing evidence that business-as-usual is not an option, but it takes issues with many of the suggested policy responses. Human wellbeing is inseparably linked to economic growth, and economic growth inevitably has environmental implications. While it is impossible to decouple these linkages, countries can promote more sustainable development pathways by altering these linkages. To this end, they have three principle policy levers, which will need to complement each other: Efforts to promote more inclusive economic growth, efforts to increase resource-efficiency, and efforts to address and harness demographic changes. The paper has important implications for the discussions on sustainable development goals and the post-2015 development agenda, which takes place at the United Nations.

Clinically Relevant Dimer Interface Mutants of STAT1 Transcription Factor Exhibit Differential Gene Expression
Julia Staab, Christoph Herrmann-Lingen, Thomas Meyer
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069903
Abstract: A transition from a parallel to an antiparallel dimer configuration of the transcription factor signal transducer and activator of transcription 1 (STAT1) is required for interferon (IFN)-mediated signal transduction. However, the precise molecular mechanisms linking conformational changes to target gene activation by STAT1 are still largely unknown. In the present study, we have characterized, in more detail than before, two disease-associated point mutants with amino acid substitutions at both sites of the dimer interface (F172W and T385A). First, we confirmed that IFNγ-stimulation of transfected cells led to enhanced tyrosine phosphorylation of mutant STAT1 as compared to the wild-type protein, which consequently resulted in its prolonged nuclear accumulation. Using an in vitro dephosphorylation assay, we demonstrated that, in contrast to wild-type STAT1 and similar to the F172W mutant, also T385A resisted enzymatic inactivation by the nuclear phosphatase Tc45. Transcriptional activation of IFNγ-driven endogenous target genes differed between wild-type and mutant STAT1. While expression of genes containing a single classical gamma-activated site (GAS), such as irf1, gpb1, and mig1, was virtually unaffected by the presence of either of two amino acid exchanges, induction of the cxcl10 and mcp1 gene was significantly enhanced. The latter two genes both contain an additional TTC/GAA binding motif separated by 10 bp from the palindromic GAS sequence. The transcriptional superiority of the mutants on these genes was reflected by their increased binding affinity to DNA fragments containing the identified “one-and-a-half-GAS” motif. In summary, our data demonstrate that two clinically relevant interface mutants of STAT1 exhibit gene-specific effects and point to the rather complex role of the assumed conformational shift between two different dimer configurations for efficient transcriptional regulation.
Why do Particle Clouds Generate Electric Charges?
Thomas P?htz,Hans J. Herrmann,Troy Shinbrot
Physics , 2010, DOI: 10.1038/nphys1631
Abstract: Grains in desert sandstorms spontaneously generate strong electrical charges; likewise volcanic dust plumes produce spectacular lightning displays. Charged particle clouds also cause devastating explosions in food, drug and coal processing industries. Despite the wide-ranging importance of granular charging in both nature and industry, even the simplest aspects of its causes remain elusive, because it is difficult to understand how inert grains in contact with little more than other inert grains can generate the large charges observed. Here, we present a simple yet predictive explanation for the charging of granular materials in collisional flows. We argue from very basic considerations that charge transfer can be expected in collisions of identical dielectric grains in the presence of an electric field, and we confirm the model's predictions using discrete-element simulations and a tabletop granular experiment.
Clustering of inelastic soft spheres in homogeneous turbulence
Thomas Burgener,Dirk Kadau,Hans Jürgen Herrmann
Physics , 2012, DOI: 10.1103/PhysRevE.86.036321
Abstract: In this paper we numerically investigate the influence of dissipation during particle collisions in an homogeneous turbulent velocity field by coupling a discrete element method to a Lattice-Boltzmann simulation with spectral forcing. We show that even at moderate particle volume fractions the influence of dissipative collisions is important. We also investigate the transition from a regime where the turbulent velocity field significantly influences the spatial distribution of particles to a regime where the distribution is mainly influenced by particle collisions.
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