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Heidelberg, Germany

Mercker M.,BioQuant | Richter T.,Institute of Applied Mathematics | Hartmann D.,BioQuant | Hartmann D.,Siemens AG
Journal of Physical Chemistry B | Year: 2011

A continuous model of two coupled monolayers constituting a fluid bilayer membrane is presented. The model is based on the minimization of a membrane free energy considering in both monolayer leaflets two different molecule types, undergoing lateral phase separation. Differences in the mechanical properties of the molecules, such as shape, stiffness, and length are accounted explicitly by the model. In the presented model, coupling between monolayers is realized via an energy-based model depending on the local distance between the two monolayers as well as the lengths of molecules constituting the local monolayer region. We numerically study different passive mechanisms for molecule sorting and correlation across the bilayer induced by first-order mechanical constraints. Here, we focus on three aspects: First, we find that stretching of the two monolayers in the normal direction yields a sorting of molecules according to their length. Furthermore, we show that the length of molecules can be used to synchronize phases across the bilayer membrane. Moreover, we find that generating curvature in one layer (induced by different curvature creating mechanisms) sorts molecules of the other layer according to their shape and stiffness. Many recent experimental data indicate the importance of specific lipid-protein interactions and the role of the bilayer thickness in membrane protein function and sorting. The presented model proposes different mechanisms leading to a colocalization of different components in different monolayers at the same place at the same time. © 2011 American Chemical Society. Source

Weber G.-W.,Institute of Applied Mathematics
Communications in Computer and Information Science | Year: 2015

Desirability functions (DFs) play an increasing role for solving the optimization of process or product quality problems having various quality characteristics to obtain a good compromise between these characteristics. There are many alternative formulations to these functions and solution strategies suggested for handling their weaknesses and improving their strength. Although the DFs of Derringer and Suich are the most popular ones in multiple-response optimization literature, there is a limited number of solution strategies to their optimization which need to be updated with new research results obtained in the area of nonlinear optimization. © Springer International Publishing Switzerland 2015. Source

Arous G.B.,New York University | Kirkpatrick K.,University of Illinois at Urbana - Champaign | Schlein B.,Institute of Applied Mathematics
Communications in Mathematical Physics | Year: 2013

We study the many body quantum evolution of bosonic systems in the mean field limit. The dynamics is known to be well approximated by the Hartree equation. So far, the available results have the form of a law of large numbers. In this paper we go one step further and we show that the fluctuations around the Hartree evolution satisfy a central limit theorem. Interestingly, the variance of the limiting Gaussian distribution is determined by a time-dependent Bogoliubov transformation describing the dynamics of initial coherent states in a Fock space representation of the system. © 2013 Springer-Verlag Berlin Heidelberg. Source

Kavun E.B.,Institute of Applied Mathematics | Yalcin T.,Institute of Applied Mathematics
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

In this paper, we present a lightweight implementation of the permutation Keccak-f[200] and Keccak-f[400] of the SHA-3 candidate hash function Keccak. Our design is well suited for radio-frequency identification (RFID) applications that have limited resources and demand lightweight cryptographic hardware. Besides its low-area and low-power, our design gives a decent throughput. To the best of our knowledge, it is also the first lightweight implementation of a sponge function, which differentiates it from the previous works. By implementing the new hash algorithm Keccak, we have utilized unique advantages of the sponge construction. Although the implementation is targeted for Application Specific Integrated Circuit (ASIC) platforms, it is also suitable for Field Programmable Gate Arrays (FPGA). To obtain a compact design, serialized data processing principles are exploited together with algorithm-specific optimizations. The design requires only 2.52K gates with a throughput of 8 Kbps at 100 KHz system clock based on 0.13-μm CMOS standard cell library. © 2010 Springer-Verlag. Source

Yerlikaya-Ozkurt F.,Institute of Applied Mathematics | Weber G.-W.,Institute of Applied Mathematics
Engineering Optimization | Year: 2014

Ground Motion Prediction Equations (GMPEs) are empirical relationships which are used for determining the peak ground response at a particular distance from an earthquake source. They relate the peak ground responses as a function of earthquake source type, distance from the source, local site conditions where the data are recorded and finally the depth and magnitude of the earthquake. In this article, a new prediction algorithm, called Conic Multivariate Adaptive Regression Splines (CMARS), is employed on an available dataset for deriving a new GMPE. CMARS is based on a special continuous optimization technique, conic quadratic programming. These convex optimization problems are very well-structured, resembling linear programs and, hence, permitting the use of interior point methods. The CMARS method is performed on the strong ground motion database of Turkey. Results are compared with three other GMPEs. CMARS is found to be effective for ground motion prediction purposes. © 2013 © 2013 Taylor & Francis. Source

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