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Karlsruhe, Germany

The Karlsruhe Institute of Technology is one of the largest and most prestigious research and education institutions in Germany known for its high quality of research work around the world.KIT was created in 2009 when the University of Karlsruhe , founded in 1825 as public research university and also known as "Fridericiana", merged with the Karlsruhe Research Centre Forschungszentrum Karlsruhe, which was originally established as a national nuclear research centre in 1956.KIT is one of the leading universities in the Engineering and Natural science in Europe, ranking sixth overall in citation impact. KIT is a member of the TU9 German Institutes of Technology e.V. As part of the German Universities Excellence Initiative KIT was accredited with the excellence status in 2006. In the 2011 performance ranking of scientific papers, Karlsruhe ranked first in Germany and among the top ten universities in Europe in engineering and natural science.In the 2013 QS World University Rankings the Karlsruhe Institute of Technology achieved 116th place in the global ranking across all disciplines and 33rd and 34th place in engineering and natural science, respectively. In the 2013 Taiwan ranking, KIT remained the best German University in the engineering and natural science, ranked in the engineering science ahead of the RWTH Aachen , the Technical University of Munich and the Technical University of Dresden . For the natural science KIT led the domestic comparison against the LMU Munich , the University of Heidelberg and the Technical University of Munich . Wikipedia.

Kara D.,Karlsruhe Institute of Technology
Nuclear Physics B | Year: 2013

We present the calculation of the mixed two-loop QCD/electroweak corrections to hadronic W boson decays within the Standard Model. The optical theorem is applied to the W boson two-point function. The multi-scale integrals are computed with the help of asymptotic expansions, which factorize the three-loop diagrams into one- and two-loop vacuum and propagator-type integrals. © 2013 Elsevier B.V.

Stein O.,Karlsruhe Institute of Technology
Mathematical Programming | Year: 2016

We introduce computable a priori and a posteriori error bounds for optimality and feasibility of a point generated as the rounding of an optimal point of the LP relaxation of a mixed integer linear optimization problem. Treating the mesh size of integer vectors as a parameter allows us to study the effect of different “granularities” in the discrete variables on the error bounds. Our analysis mainly bases on a global error bound for mixed integer linear problems constructed via a so-called grid relaxation retract. Relations to proximity results, the integer rounding property, and binary analytic problems are highlighted. © 2015, Springer-Verlag Berlin Heidelberg and Mathematical Optimization Society.

Biedermann F.,Karlsruhe Institute of Technology | Schneider H.-J.,Saarland University
Chemical Reviews | Year: 2016

On the basis of many literature measurements, a critical overview is given on essential noncovalent interactions in synthetic supramolecular complexes, accompanied by analyses with selected proteins. The methods, which can be applied to derive binding increments for single noncovalent interactions, start with the evaluation of consistency and additivity with a sufficiently large number of different host-guest complexes by applying linear free energy relations. Other strategies involve the use of double mutant cycles, of molecular balances, of dynamic combinatorial libraries, and of crystal structures. Promises and limitations of these strategies are discussed. Most of the analyses stem from solution studies, but a few also from gas phase. The empirically derived interactions are then presented on the basis of selected complexes with respect to ion pairing, hydrogen bonding, electrostatic contributions, halogen bonding, π-π-stacking, dispersive forces, cation-π and anion-π interactions, and contributions from the hydrophobic effect. Cooperativity in host-guest complexes as well as in self-assembly, and entropy factors are briefly highlighted. Tables with typical values for single noncovalent free energies and polarity parameters are in the Supporting Information. © 2016 American Chemical Society.

Sharipov F.,Karlsruhe Institute of Technology
Physica A: Statistical Mechanics and its Applications | Year: 2010

The OnsagerCasimir reciprocal relations obtained for gaseous systems on the basis of the linearized Boltzmann equation in a general form [F. Sharipov, OnsagerCasimir reciprocal relations based on the Boltzmann equation and gassurface interaction law. Single gas., Phys. Rev. E 73 (2006) 026110] are applied to boundless domains. Under additional assumptions, expressions of the kinetic coefficients obtained previously are significantly simplified and can be easily applied in practice. In contrast to all previous works on this topic, it is shown that for a given set of thermodynamic forces there are several sets of thermodynamic fluxes providing the same entropy production. As a consequence, several forms of the kinetic coefficients satisfying the reciprocal relations do exist for a given set of thermodynamic forces. An illustrative example confirms that in many situations the kinetic coefficients are neither odd nor even with respect to the time-reversal and hence the reciprocal relations between them should be written in more general form than that obtained by Casimir. © 2010 Elsevier B.V.

Peters H.,Karlsruhe Institute of Technology
Journal of Statistical Physics | Year: 2010

In physics, there are two distinct paradoxes, which are both known as the "Gibbs paradox". This article is concerned with only one of them: the false increase in entropy, which is calculated from the process of combining two gases of the same kind consisting of distinguishable particles. In the following, this paradox will be referred to as the Gibbs paradox of the first kind (GP1). (Two particles are said to be distinguishable if they are either non-identical, that is, if they have different properties, or if they are identical and there are microstates which change under transposition of the two particles.) The GP1 is demonstrated and subsequently analyzed. The analysis shows that, for (quantum or classical) systems of distinguishable particles, it is generally uncertain of which particles they consist. The neglect of this uncertainty is the root of the GP1. For the statistical description of a system of distinguishable particles, an underlying set of particles, containing all particles that in principle qualify for being part of the system, is assumed to be known. Of which elements of this underlying particle set the system is composed, differs from microstate to microstate. Thus, the system is described by an ensemble of possible particle compositions. The uncertainty about the particle composition contributes to the entropy of the system. Systems for which all possible particle compositions are equiprobable will be called harmonic. Classical systems of distinguishable identical particles are harmonic as a matter of principle; quantum or classical systems of non-identical particles are not necessarily harmonic, since for them the composition probabilities depend individually on the preparation of the system. Harmonic systems with the same underlying particle set are always correlated; hence, for harmonic systems, the entropy is no longer additive and loses its thermodynamic meaning. A quantity derived from entropy is introduced, the reduced entropy, which, for harmonic systems, replaces the entropy as thermodynamic potential. For identical classical particles, the equivalence (in particular with respect to the second law of thermodynamics) between distinguishability and indistinguishability is proved. The resolution of the GP1 is demonstrated applying the previously found results. © 2010 The Author(s).

Klinkhamer F.R.,Karlsruhe Institute of Technology
JETP Letters | Year: 2013

The effective potential of the Higgs scalar field in the Standard Model may have a second degenerate minimum at an ultrahigh vacuum expectation value. This second minimum then determines, by radiative corrections, the values of the top-quark and Higgs-boson masses at the standard minimum corresponding to the electroweak energy scale. An argument is presented that this ultrahigh vacuum expectation value is proportional to the energy scale of gravity, EPlanck ≡ √h{stroke}c 5/GN considered to be characteristic of a spacetime foam. In the context of a simple model, the existence of kink-type wormhole solutions places a lower bound on the ultrahigh vacuum expectation value and this lower bound is of the order of EPlanck. © 2013 Pleiades Publishing, Ltd.

Schmalz C.,University of Tubingen | Frimmel F.H.,Karlsruhe Institute of Technology | Zwiener C.,University of Tubingen
Water Research | Year: 2011

Trichloramine is a volatile, irritant compound of penetrating odor, which is found as a disinfection by-product in the air of chlorinated indoor swimming pools from reactions of nitrogenous compounds with chlorine. Acid amides, especially urea, ammonium ions and α-amino acids have been found as most efficient trichloramine precursors at acidic and neutral pH. For urea a relative NCl3 formation of 96% at pH 2.5 and 76% at pH 7.1 was determined. Even under sub-stoichiometric molar ratios of Cl/N the formation of NCl3 is favored over mono and dichlorinated products. However, the reaction kinetics of urea with chlorine is slow under conditions relevant for swimming pools. Also the mass transfer of NCl3 from water to the gas phase which was calculated by the Deacon's boundary layer model could be shown as a relatively slow process. Mass transfer would take 20 h or 5.8 d for a rough or a quiescent surface of the water, respectively. This is much more than a typical turnover rate of 6-8 h of a treatment cycle of a 25 m swimming pool. Therefore processes to remove NCl3 and its precursors can help to minimize the exposure of bathers. © 2011 Elsevier Ltd.

Rothlingshofer M.,Karlsruhe Institute of Technology | Richert C.,University of Stuttgart
Journal of Organic Chemistry | Year: 2010

Template-directed primer extension usually requires a polymerase, nucleoside triphosphates, and magnesium ions as cofactors. Enzyme-free, chemical primer extensions are known for preactivated nucleotides at millimolar concentrations. Based on a screen of carbodiimides, heterocyclic catalysts, and reactions conditions, we now show that near-quantitative primer conversion can be achieved at submillimolar concentration of any of the four deoxynucleotides (dAMP, dCMP, dGMP and dTMP). The new protocol relies on in situ activation with EDC and 1-methylimidazole and a magnesium-free buffer that was tested successfully for different sequence motifs. The method greatly simplifies chemical primer extension assays, further reduces the cost of such assays, and demonstrates the potential of the in situ activation approach. © 2010 American Chemical Society.

Klinkhamer F.R.,Karlsruhe Institute of Technology
Modern Physics Letters A | Year: 2013

An exact solution of the vacuum Einstein field equations over a nonsimply-connected manifold is presented. This solution is spherically symmetric and has no curvature singularity. It can be considered as a regularization of the Schwarzschild solution over a simply-connected manifold, which has a curvature singularity at the center. Spherically symmetric collapse of matter in 4 may result in this nonsingular black-hole solution, if quantum-gravity effects allow for topology change near the center. © 2013 World Scientific Publishing Company.

Hatta Y.,Kyoto University | Ueda T.,Karlsruhe Institute of Technology
Nuclear Physics B | Year: 2013

In the context of inter-jet energy flow, we present the first quantitative result of the resummation of non-global logarithms at finite Nc. This is achieved by refining Weigert's approach in which the problem is reduced to the simulation of associated Langevin dynamics in the space of Wilson lines. We find that, in e+e- annihilation, the exact result is rather close to the result previously obtained in the large-Nc mean field approximation. However, we observe enormous event-by-event fluctuations in the Langevin process which may have significant consequences in hadron collisions. © 2013 Elsevier B.V.

Schulz H.,Karlsruhe Institute of Technology
Catalysis Today | Year: 2014

Unsteady initial regimes of Fischer-Tropsch synthesis with iron and cobalt catalysts have been investigated for changes in rate and selectivity, applying own-developed methods for temporal resolution of product composition. Using the kinetic model of non-trivial surface-polymerization, probabilities of reactions of chemisorbed intermediates are calculated as function of time and carbon number of species, at several sets of reaction parameters and different catalyst properties. Results are used to elucidate principles of selforganization. The rules of iron catalyst selforganization are dominated by alkali promoting, as controlling iron phase composition and the relative rate of reaction of on-site-carbon for FT-monomer formation, Fe-carbide formation and carbon-phase formation - these as in relation to primary and secondary formation of olefins and paraffins. With cobalt as catalyst, selforganization for creating different kinds of active sites for primary and secondary reactions appears essential, and is explained via the observed selectivity changes. A dynamic structure of active sites is proposed. Probability of linear chain prolongation is merely carbon number dependent, but probability of growth with chain branching declines exponentially with carbon number, indicating increasing spatial constraints on the reaction. Selectivity changes are mechanistically understood from the ordered complexity of product composition. © 2014 Elsevier B.V. All rights reserved.

Friedewald M.,Fraunhofer Institute for Systems and Innovation Research | Raabe O.,Karlsruhe Institute of Technology
Telematics and Informatics | Year: 2011

Ubiquitous computing is considered as a promising technological path of innovation. Intensive R&D activities and political strategies are addressing the objective to foster marketable technologies and applications. This article explores the state-of-the-art on the way towards the "Internet of things". Which application fields have already proved their potential for realising the vision and promises related to the new technology? What are the technical, legal and social challenges that have to be addressed - and how can policy-makers contribute? We deal with these questions in the light of recent developments in research and business, illustrating the findings by examples in retail, logistics and health care. The article concludes that further efforts by all stakeholders from businesses, society and politics are necessary to make ubiquitous computing applications economically sustainable and socially compatible in order to tap its full potential. © 2010 Elsevier Ltd. All rights reserved.

Kirsch A.,Karlsruhe Institute of Technology | Lechleiter A.,University of Bremen
Inverse Problems | Year: 2013

This paper investigates the relationship between interior transmission eigenvalues k0 > 0 and the accumulation point 1 of the eigenvalues of the scattering operator when k approaches k0. As is well known, the spectrum of is discrete, the eigenvalues μn(k) lie on the unit circle in and converge to 1 from one side depending on the sign of the contrast. Under certain (implicit) conditions on the contrast it is shown that interior transmission eigenvalues k0 can be characterized by the fact that one eigenvalue of converges to 1 from the opposite side if k tends to k0 from below. The proof uses the Cayley transform, Courant's maximum-minimum principle, and the factorization of the far field operator. For constant contrasts that are positive and large enough or negative and small enough, we show that the conditions necessary to prove this characterization are satisfied at least for the smallest transmission eigenvalue. © 2013 IOP Publishing Ltd.

McHedlidze T.,Karlsruhe Institute of Technology
Computational Geometry: Theory and Applications | Year: 2013

We prove that every n-vertex oriented path admits an upward planar embedding on every general set of (n-1)2+1 points on the plane. This result improves the previously known upper bound which is exponential in the number of switches of the given oriented path (Angelini et al. 2010) [1]. © 2013 Published by Elsevier B.V.

This article deals with the question, to what extent damping due to nonsmooth Coulomb friction may affect the stability and bifurcation behavior of vibrational systems with self-excitation due to negative effective damping which-for the smooth case-is related to a Hopf bifurcation of the steady state. Without damping due to Coulomb friction, the stability of the trivial solution is controlled by the effective viscous damping of the system: as the damping becomes negative, the steady state loses stability at a Hopf point. Adding Coulomb friction changes the trivial solution into a set of equilibria, which-for oscillatory systems-is asymptotically stable for all values of effective viscous damping. The Hopf point vanishes and an unstable limit cycle appears which borders the basin of attraction of the equilibrium set. Moreover, the influence of nonlinear damping terms is discussed. The effect of Coulomb frictional damping may be seen as adding an imperfection to the classical smooth Hopf scenario: as the imperfection vanishes, the behavior of the smooth problem is recovered. © 2012 Springer Science+Business Media B.V.

Gleiter H.,Karlsruhe Institute of Technology | Gleiter H.,Nanjing University of Science and Technology
Beilstein Journal of Nanotechnology | Year: 2013

Nanoglasses are a new class of noncrystalline solids. They differ from today's glasses due to their microstructure that resembles the microstructure of polycrystals. They consist of regions with a melt-quenched glassy structure connected by interfacial regions, the structure of which is characterized (in comparison to the corresponding melt-quenched glass) by (1) a reduced (up to about 10%) density, (2) a reduced (up to about 20%) number of nearest-neighbor atoms and (3) a different electronic structure. Due to their new kind of atomic and electronic structure, the properties of nanoglasses may be modified by (1) controlling the size of the glassy regions (i.e., the volume fraction of the interfacial regions) and/or (2) by varying their chemical composition. Nanoglasses exhibit new properties, e.g., a Fe90Sc10 nanoglass is (at 300 K) a strong ferromagnet whereas the corresponding melt-quenched glass is paramagnetic. Moreover, nanoglasses were noted to be more ductile, more biocompatible, and catalytically more active than the corresponding melt-quenched glasses. Hence, this new class of noncrystalline materials may open the way to technologies utilizing the new properties. © 2013 Gleiter; licensee Beilstein-Institut.

Kondov I.,Karlsruhe Institute of Technology
Natural Computing | Year: 2013

Particle swarm optimization is a powerful technique for computer aided prediction of proteins' three-dimensional structure. In this work, employing an all-atom force field and the standard algorithm, as implemented in the ArFlock library in previous work, the low-energy conformations of several peptides of different sizes in vacuum starting from completely extended conformations are investigated. The computed structures are in good overall agreement with experimental data and results from other computer simulations. Periodic boundary conditions applied to the search space improve the performance of the method dramatically, especially when the linear velocity update rule is used. It is also shown that asynchronous parallelization speeds up the simulation better than the synchronous one and reduces the effective time for predictions significantly. © 2012 Springer Science+Business Media B.V.

Petney T.N.,Karlsruhe Institute of Technology
International journal for parasitology | Year: 2013

Clonorchis sinensis, Opisthorchis felineus and Opisthorchis viverrini are the three most important liver flukes involved in human health, infecting more than 45 million people worldwide. Both C. sinensis and O. viverrini, and possibly O. felineus, can induce human cholangiocarcinoma as well as inducing other hepatobiliary pathology. Although the life cycles of all three species are similar, only that of O. felineus in Europe remains predominantly zoonotic, while O. felineus in Asia and C. sinensis have a stronger mixture of zoonotic and anthroponotic components in their life cycles. Opisthorchis viverrini from the Mekong area of southeastern Asia is predominantly anthroponotic. Here we discuss the comparative epidemiology of these three taxa comparing in detail the use of first, second and final animal hosts, and consider the potential role of humans in spreading these pathogens. In addition we discuss the genetic structure of all three species in relation to potentially cryptic species complexes. Copyright © 2013 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Hergert T.,Karlsruhe Institute of Technology | Heidbach O.,German Research Center for Geosciences
Nature Geoscience | Year: 2010

The slip rate along a fault controls the accumulation of strain that is eventually released during an earthquake. Along a 150-km-long stretch of the North Anatolian fault near Istanbul, Turkey, strain has been building up 2 since the last large earthquake in 1766. Estimates of the geodetic slip rates along the main Marmara fault vary widely, ranging between 17 and 27.9 mm yr-1 (refs 2-5). This slip rate is difficult to quantify because of the lack of satellite observations offshore and the complexity of the submarine fault system that includes the main Marmara fault2,6,7. Here we estimate the right-lateral slip rate on the main Marmara fault using a three-dimensional geomechanical model that incorporates these structural complexities. From our simulations we infer slip rates between 12.8 and 17.8 mm yr-1; our estimates are smaller and more variable than previous results, primarily because of slip partitioning and internal deformation. Our model results reconcile geodetic observations and geological fault slip rates8-10, which had been considered conflicting previously. We suggest that the inferred variability in slip rate on the main Marmara fault favours segmented release of seismic moment during consecutive events over the failure of the whole seismic gap in one large earthquake. © 2010 Macmillan Publishers Limited. All rights reserved.

Werle P.,Karlsruhe Institute of Technology
Agricultural and Forest Meteorology | Year: 2010

In ecosystem research laser based gas monitors are increasingly used to measure fluxes of methane, nitrous oxide and even stable carbon isotopes. As these complex measurement devices under field conditions cannot be considered as absolutely stable, drift characterization is an issue to distinguish between atmospheric data and sensor drift. In this paper the concept of the two sample variance is utilized in analogy to previous stability investigations to characterize the stationarity of spectroscopic and micrometeorological data in the time domain. The main results of the study are practical guidelines how to use the method for eddy-covariance determination of ecosystem exchange by laser-optical instruments suffering from signal instability. As an example, the method is applied to assess the high-pass filter time constant for detrending of time series data. The method described here provides information similar to existing characterizations as the ogive analysis, the normalized error variance of the second order moment as well as information about the spectral characteristics of turbulence in the inertial subrange. The method is easy to implement and, therefore, well suited to assist as a useful tool for a routine data quality check for both, new practitioners and experts in the field. © 2009 Elsevier B.V.

Worsch T.,Karlsruhe Institute of Technology
Natural Computing | Year: 2013

We consider asynchronous one-dimensional cellular automata (CA). It is shown that there is one with von Neumann neighborhood of radius 1 which can simulate each asynchronous one-dimensional cellular automaton. Analogous constructions are described for α-asynchronous CA (where each cell independently enters a new state with probability α, and for "neighborhood independent" asynchronous CA (where never two cells are updated simultaneously if one is in the neighborhood of the other). This also gives rise to a construction for so-called fully asynchronous CA (where in each step exactly one cell is updated). © 2013 Springer Science+Business Media Dordrecht.

Puchta H.,Karlsruhe Institute of Technology | Hohn B.,Friedrich Miescher Institute for Biomedical Research
Plant Cell | Year: 2012

Marker-transgene-dependent lines of Arabidopsis thaliana measuring somatic homologous recombination (SHR) have been available for almost two decades. Here we discuss mechanisms of marker-gene restoration, comment on results obtained using the reporter lines, and stress how caution must be applied to avoid experimental problems or false interpretation in the use of SHR reporter lines. Although theoretically possible, we conclude that explanations other than SHR are unlikely to account for restoration of marker gene expression in the SHR lines when used with appropriate controls. We provide an overview of some of the most important achievements obtained with the SHR lines, give our view of the limitations of the system, and supply the reader with suggestions on the proper handling of the SHR lines. We are convinced that SHR lines are and will remain in the near future a valuable tool to explore the mechanism and influence of external and internal factors on genome stability and DNA repair in plants. © 2012 American Society of Plant Biologists.

Steinbrecher T.,Karlsruhe Institute of Technology
Methods in molecular biology (Clifton, N.J.) | Year: 2013

Molecular dynamics simulations of biomolecules have matured into powerful tools of structural biology. In addition to the commonly used empirical force field potentials, quantum mechanical descriptions are gaining popularity for structure optimization and dynamic simulations of peptides and proteins. In this chapter, we introduce methodological developments such as the QM/MM framework and linear-scaling QM that make efficient calculations on large biomolecules possible. We identify the most common scenarios in which quantum descriptions of peptides and proteins are employed, such as structural refinement, force field development, treatment of unusual residues, and predicting spectroscopic and exited state properties. The benefits and shortcomings of QM potentials, in comparison to classical force fields, are discussed, with special emphasis on the sampling problems of protein conformational space. Finally, recent examples of QM/MM calculations in light-sensitive membrane proteins illustrate typical applications of the reviewed methods.

Steinbruck M.,Karlsruhe Institute of Technology
Journal of Nuclear Materials | Year: 2014

This paper presents for the first time results of the reaction between oxygen-stabilized α-Zr(O) and nitrogen. This reaction plays an important role during air oxidation of zirconium and its alloys. A wide range of temperatures (1073-1673 K) and composition of the α-Zr(O) phase (1.5-6.5 wt.% oxygen) was investigated in thermo-gravimetric experiments. The reaction is of linear kinetics and much faster than the reaction of the oxygen-free metal (alloy) with nitrogen. Strong dependencies on temperature and initial composition of the α-Zr(O) were found. The reaction kinetics becomes faster with increasing temperature up to 1470 K before it slows down with further rising temperatures. The strong dependence on the oxygen content in the metal could be best described by a fourth root correlation of the linear reaction rate constants. © 2014 Elsevier B.V. All rights reserved.

Helwig S.,Friedrich - Alexander - University, Erlangen - Nuremberg | Branke J.,University of Warwick | Mostaghim S.,Karlsruhe Institute of Technology
IEEE Transactions on Evolutionary Computation | Year: 2013

Many practical optimization problems are constrained and have a bounded search space. In this paper, we propose and compare a wide variety of bound handling techniques for particle swarm optimization. By examining their performance on flat landscapes, we show that many bound handling techniques introduce significant search bias. Furthermore, we compare the performance of many bound handling techniques on a variety of test problems, demonstrating that the bound handling technique can have a major impact on the algorithm performance, and that the method recently proposed as the standard does not, in general, perform well. © 1997-2012 IEEE.

Reviakine I.,Karlsruhe Institute of Technology
Clinical Hemorheology and Microcirculation | Year: 2015

Recent years have been ripe with discoveries of non-haemostatic platelet functions. This led to the appreciation of the significant, previously unknown, role played by the platelets in various pathologies and regenerative processes. As a result, exciting opportunities for clinical applications in fields as diverse as regenerative medicine and cancer treatment are emerging. However, their realization depends on the understanding of the regulatory mechanisms governing these diverse platelet functions, so that particular platelet responses could be artificially tailored to specific clinical situations. Current understanding of the signalling pathways controlling haemostatic responses is rooted in the development of quantitative assays for measuring them and sensitive markers for their quantification. However, the existing assays and markers are not sufficiently sensitive for distinguishing between individual signalling pathways and unravelling inter-pathway connections. Moreover, entirely new approaches are needed for studying non-haemostatic platelet functions, since there are currently no assays or markers for quantifying them.We review the on-going efforts in these directions, including our own recent work on using lectins as sensitive probes for profiling platelet activation. © 2015 - IOS Press and the authors.

Hedde P.N.,Karlsruhe Institute of Technology
Nature communications | Year: 2013

Raster image correlation spectroscopy is a powerful tool to study fast molecular dynamics such as protein diffusion or receptor-ligand interactions inside living cells and tissues. By analysing spatio-temporal correlations of fluorescence intensity fluctuations from raster-scanned microscopy images, molecular motions can be revealed in a spatially resolved manner. Because of the diffraction-limited optical resolution, however, conventional raster image correlation spectroscopy can only distinguish larger regions of interest and requires low fluorophore concentrations in the nanomolar range. Here, to overcome these limitations, we combine raster image correlation spectroscopy with stimulated emission depletion microscopy. With imaging experiments on model membranes and live cells, we show that stimulated emission depletion-raster image correlation spectroscopy offers an enhanced multiplexing capability because of the enhanced spatial resolution as well as access to 10-100 times higher fluorophore concentrations.

Hoffmann K.-H.,Karlsruhe Institute of Technology
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

CMS has started a campaign to identify the future sensor technology baseline for the Tracker Upgrade Phase II. A large variety of 6-in. wafers of different thicknesses and technologies have been ordered. The sensor properties and especially the behavior after irradiation will be investigated for floatzone, magnetic Czochralski and epitaxial silicon material with dedicated test structures. The sensors come in p-in-n and n-in-p versions. The p-stop as well as p-spray isolation technologies will be explored for the n-in-p type sensors. Some additional wafers will come with an additional routing in a second metal layer on selected structures. Approximately one half of these wafers have already been delivered. Pre-qualification has just started. © 2011 Elsevier B.V.

Barth C.,Karlsruhe Institute of Technology
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

The CMS silicon strip tracker is the largest detector of its kind. It is expected to operate at the LHC for more than 10 years. In order to quantify aging effects, it is important to keep track of the evolution of fundamental detector properties under radiation and thermal fluctuations. Our aim is to define monitoring procedures to determine the characteristics regularly. In this paper we focus on the silicon sensors full depletion voltage. We present the first results obtained with two different methods: a standard one with signal from particles and a newly developed approach based on noise. In addition we compare our output with the C-V measurements performed during the construction. © 2011 Elsevier B.V.

Campanario F.,Karlsruhe Institute of Technology
Journal of High Energy Physics | Year: 2011

In this work, some of the NLO QCD corrections for pp → V V jj +X are presented. A program in Mathematica based on the structure of FeynCalc which automatically simplifies a set of amplitudes up to the hexagon level of rank 5 has been created for this purpose. We focus on two different topologies. The first involves all the virtual contributions needed for quadruple electroweak vector boson production, i.e. pp → V V V V + X. In the second, the remaining "bosonic" corrections to electroweak triple vector boson production with an additional jet (pp → V V V j+X) are computed. We show the factorization formula of the infrared divergences of the bosonic contributions for VVVV and VVVj production with V ε (W,Z, γ). Stability issues associated with the evaluation of the hexagons up to rank 5 are studied. The CPU time of the FORTRAN subroutines rounds the 2 milliseconds and seems to be competitive with other more sophisticated methods. Additionally, in appendix A the master equations to obtain the tensor coefficients up to the hexagon level in the external momenta convention are presented including the ones needed for small Gram determinants. © 2011 SISSA.

Kiewisch K.,VU University Amsterdam | Jacob C.R.,Karlsruhe Institute of Technology | Visscher L.,VU University Amsterdam
Journal of Chemical Theory and Computation | Year: 2013

The ability to calculate accurate electron densities of full proteins or of selected sites in proteins is a prerequisite for a fully quantum-mechanical calculation of protein-protein and protein-ligand interaction energies. Quantum-chemical subsystem methods capable of treating proteins and other biomolecular systems provide a route to calculate the electron densities of proteins efficiently and further make it possible to focus on specific parts. Here, we evaluate and extend the 3-partition frozen-density embedding (3-FDE) scheme [Jacob, C. R.; Visscher, L. J. Chem. Phys.2008, 128, 155102] for this purpose. In particular, we have extended this scheme to allow for the treatment of disulfide bridges and charged amino acid residues and have introduced the possibility to employ more general partitioning schemes. These extensions are tested both for the prediction of full protein electron densities and for focusing on the electron densities of a selected protein site. Our results demonstrate that 3-FDE is a promising tool for the fully quantum-chemical treatment of proteins. © 2013 American Chemical Society.

Harth A.,Karlsruhe Institute of Technology
Journal of Web Semantics | Year: 2010

Web standards such as RDF (Resource Description Framework) facilitate data integration over large number of sources. The resulting interlinked datasets describe objects, their attributes and links to other objects. Such datasets are amenable for queries beyond traditional keyword search and for visualisation beyond a simple list of links to documents. Given that data integrated from the open web exhibits enormous variety in scope and structure, the mechanisms for interacting with such data have to be generic and agnostic to the vocabularies used. Ideally, a system operating on web data is easy to use without upfront training. To this end, we present VisiNav, a system based on an interaction model designed to easily search and navigate large amounts of web data (the current system contains over 18.5m RDF triples aggregated from 70k sources). In this paper we introduce a formal query model comprising four atomic operations over object-structured datasets: keyword search, object focus, path traversal, and facet specification. From these atomic operations, users incrementally assemble complex queries that yield trees of objects as result. These results can then be either directly visualised or exported to application programs or online services for further processing. The current system provides detail, list, and table views for arbitrary types of objects; and timeline and map visualisations for temporal and spatial aspects of objects. © 2010 Elsevier B.V. All rights reserved.

Mauder M.,Karlsruhe Institute of Technology
Boundary-Layer Meteorology | Year: 2013

Kochendorfer et al. (Boundary-Layer Meterol, 145:383-398, 2012) conducted an experiment to evaluate azimuth and angle-of-attack dependent errors of sonic anemometer measurements. Several questions are raised regarding the experimental design and the presented results. The finding that instruments with non-orthogonal sonic paths underestimate fluctuations of vertical wind speed and consequently also scalar fluxes by about 10 % is compared with the results of a hitherto unpublished side-by-side field comparison and other past intercomparison experiments. Scale considerations are presented that raise considerable doubts on the validity of the implicit assumption of Kochendorfer et al. (2012) that the turbulent wind vector is highly correlated across a distance of 1. 2 m at a height of 2. 5 m over flat grassland, which corresponds to the separation between the sonic anemometers tested in their experiment. Nevertheless, new developments in sonic anemometer design to minimize transducer-shadow effects are desirable. © 2012 Springer Science+Business Media Dordrecht.

Metzler M.,Karlsruhe Institute of Technology
Mycotoxin Research | Year: 2011

The Fusarium mycotoxin zearalenone is a frequent contaminant of food and feed. Up to now, different abbreviations and counting systems for the numerous positions of this macrocyclic -resorcylic acid lactone and its metabolites have been used. As the number of identified fungal and mammalian metabolites of zearalenone is still growing, the lack of a uniform designation makes the literature on these important toxins confusing and complicated. Here, we propose a logical set of abbreviations and a simple counting system, in order to facilitate future research communications on zearalenone and its congeners. © 2010 Society for Mycotoxin Research and Springer.

Lohneysen H.V.,Karlsruhe Institute of Technology
Annalen der Physik (Leipzig) | Year: 2011

The metal-insulator (MI) transition in Si:P can be tuned by varying the P concentration or - for barely insulating samples - by application of uniaxial stress S. On-site Coulomb interactions lead to the formation of localized magnetic moments and the Kondo effect on the metallic side, and to a Hubbard splitting of the donor band on the insulating side. Continuous stress tuning allows the observation of finite-temperature dynamic scaling of δ (T,S) and hence a reliable determination of the critical exponent μ of the extrapolated zero-temperature conductivity δ (0) ∼ | S - S c | μ, i.e., μ = 1, and of the dynamical exponent z = 3. The issue of half-filling vs. away from half-filling of the donor band (i.e., uncompensated vs. compensated semiconductors) is discussed in detail. The metal-insulator (MI) transition in Si:P can be tuned by varying the P concentration or - for barely insulating samples - by application of uniaxial stress S. On-site Coulomb interactions lead to the formation of localized magnetic moments and the Kondo effect on the metallic side, and to a Hubbard splitting of the donor band on the insulating side. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Steinbruck M.,Karlsruhe Institute of Technology
Annals of Nuclear Energy | Year: 2014

Boron carbide (B4C) is widely used as neutron absorbing control rod material in light water reactors (LWRs). It was also applied in all units of the Fukushima Dai-ichi nuclear power plant. Although the melting temperature of B4C is 2450 C, it initiates local, but significant melt formation in the core at temperatures around 1250 C due to eutectic interactions with the surrounding steel structures. The B4C containing melt relocates and hence transports material and energy to lower parts of the fuel bundle. It is chemically aggressive and may attack other structure materials. Furthermore, the absorber melt is oxidized by steam very rapidly and thus contributes to the hydrogen source term in the early phase of a severe accident. After failure of the control rod cladding B4C reacts with the oxidizing atmosphere. This reaction produces CO, CO2, boron oxide and boric acids, as well as significant amount of hydrogen. It is strongly exothermic, thus causing considerable release of energy. No or only insignificant formation of methane was observed in all experiments with boron carbide. The paper will summarize the current knowledge on boron carbide behavior during severe accidents mainly based on experiments performed at KIT, and will try, also in the light of the Fukushima accidents, to draw some common conclusions on the behavior of B 4C during severe accidents with the main focus on the consequences for core degradation and hydrogen source term. © 2013 Elsevier Ltd. All rights reserved.

Mione M.,Karlsruhe Institute of Technology | Bosserhoff A.,Friedrich - Alexander - University, Erlangen - Nuremberg
Pigment Cell and Melanoma Research | Year: 2015

Summary: The importance of microRNAs as key molecular components of cellular processes is now being recognized. Recent reports have shown that microRNAs regulate processes as diverse as protein expression and nuclear functions inside cells and are able to signal extracellularly, delivered via exosomes, to influence cell fate at a distance. The versatility of microRNAs as molecular tools inspires the design of novel strategies to control gene expression, protein stability, DNA repair and chromatin accessibility that may prove very useful for therapeutic approaches due to the extensive manageability of these small molecules. However, we still lack a comprehensive understanding of the microRNA network and its interactions with the other layers of regulatory elements in cellular and extracellular functions. This knowledge may be necessary before we exploit microRNA versatility in therapeutic settings. To identify rules of interactions between microRNAs and other regulatory systems, we begin by reviewing microRNA activities in a single cell type: the melanocyte, from development to disease. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Kamleitner I.,Karlsruhe Institute of Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

Relying only on first principles, we derive a master equation of Lindblad form generally applicable for adiabatically driven time-dependent systems. Our analysis shows that the much-debated secular approximation can be valid for slowly time-dependent Hamiltonians when performed in an appropriate basis. We apply our approach to the well-known Landau-Zener problem, where we find that adiabaticity is improved by coupling to a low-temperature environment. © 2013 American Physical Society.

Fischer J.,Karlsruhe Institute of Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

We show how to modify the linear-time construction algorithm for suffix arrays based on induced sorting (Nong et al., DCC'09) such that it computes the array of longest common prefixes (LCP-array) as well. Practical tests show that this outperforms recent LCP-array construction algorithms (Gog and Ohlebusch, ALENEX'11). © 2011 Springer-Verlag.

Glucuronidation constitutes an important pathway in the phase II metabolism of the mycotoxin zearalenone (ZEN) and the growth promotor α-zearalanol (α-ZAL, zeranol), but the enzymology of their formation is yet unknown. In the present study, ZEN, α-ZAL and four of their major phase I metabolites were glucuronidated in vitro using hepatic microsomes from steer, pig, rat and human, intestinal microsomes from humans, and eleven recombinant human UDP-glucuronosyltransferases (UGTs). After assigning chemical structures to the various glucuronides by using previously published information, the enzymatic activities of the various microsomes and UGT isoforms were determined together with the patterns of glucuronides generated. All six compounds were good substrates for all microsomes studied. With very few exceptions, glucuronidation occurred preferentially at the sterically unhindered phenolic 14-hydroxyl group. UGT1A1, 1A3 and 1A8 had the highest activities and gave rise to the phenolic glucuronide, whereas glucuronidation of the aliphatic hydroxyl group was mostly mediated by UGT2B7 with low activity. Based on these in vitro data, ZEN, α-ZAL and their metabolites must be expected to be readily glucuronidated both in the liver and intestine as well as in other extrahepatic organs of humans and various animal species.

Reuschle C.,Karlsruhe Institute of Technology | Weinzierl S.,Johannes Gutenberg University Mainz
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We present the decomposition of QCD partial amplitudes into primitive amplitudes at one-loop level and tree level for arbitrary numbers of quarks and gluons. Our method is based on shuffle relations. This method is purely combinatorial and does not require the inversion of a system of linear equations. © 2013 American Physical Society.

Fichtner M.,Karlsruhe Institute of Technology
Physical Chemistry Chemical Physics | Year: 2011

Nanoconfinement effects have been studied to understand and to modify thermodynamic and kinetic properties of energy storage materials and to improve their cyclic behaviour. The paper addresses various aspects in the research and development of hydrogen storage materials and batteries. Fundamental relationships and the state-of-the art in the prediction of properties and experimental observations will be outlined and structure-property-relationships will be discussed for some hydrogen storage materials. Similar nanoconfinement effects in lithium battery anode materials will be addressed. © 2011 the Owner Societies.

Wang C.,Karlsruhe Institute of Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

The rates of convergence for the partial-wave expansion with odd-power r12 terms for the ground-state energy of the helium atom are derived. For both the second-order 1/Z expansion and the Rayleigh-Ritz variational method, the energy increments of the partial-wave expansion converge as O(L -N-7), where N is the highest odd-power r12 function. The derivations require assumptions of the regularities for the ground-state helium wave function, which have not been established. Numerical results are presented for supporting the theoretical rates of convergence. © 2013 American Physical Society.

Barthlott C.,Karlsruhe Institute of Technology | Kirshbaum D.J.,McGill University
Quarterly Journal of the Royal Meteorological Society | Year: 2013

The influence of mountainous islands on the initiation of deep convection is investigated using the Consortium for Small-scale Modeling (COSMO) model. A case study and sensitivity analysis is performed for 26 August 2009, when moist convection occurred over both Corsica and Sardinia islands in the western Mediterranean Sea. Sensitivity runs with systematically modified topography are explored to evaluate the relative importance of the land-sea contrast and the terrain height for convection initiation. Whereas no island precipitation is simulated when the islands are completely removed, all simulations that represent these land surfaces develop convective precipitation. Although convection initiates progressively earlier in the day over taller islands, the precipitation rates and accumulations do not show a fixed relationship with terrain height. This is due to the competing effects of different physical processes. Firstly, whereas the forcing for low-level ascent increases over taller islands the boundary-layer moisture supply decreases, which diminishes the conditional instability and precipitable water. Secondly, whereas taller islands enhance the inland propagation speeds of sea-breeze fronts they also block these fronts mechanically and prevent them from reaching the island interior. As a result, the island precipitation is rather insensitive to island terrain height except for one particular case in which the island precipitation increases considerably due to an optimal superposition of the sea breeze and upslope flow. Comparing the two islands, convective precipitation develops earlier over Corsica due to its increased terrain height and reduced convective inhibition. However, precipitation amounts are substantially larger over Sardinia, where a stronger land-sea contrast gives rise to a more intense and organized line of sea-breeze convergence. These results demonstrate the complexity of interactions between sea breezes and orography and reinforce that an adequate representation of detailed topographic features is necessary to account for thermally induced wind systems that initiate deep convection. © 2013 Royal Meteorological Society.

Osinov V.A.,Karlsruhe Institute of Technology
Acta Geotechnica | Year: 2013

High residual pore pressure observed in the vicinity of piles driven in saturated soil indicates that the soil around the pile may be liquefied. In the present paper, the problem of deformation of saturated sand around a vibrating pile is formulated with the use of a high-cycle accumulation model capable of describing a large number of cycles. The problem is solved numerically for locally undrained conditions in spherically symmetric formulation suitable for the lower part of a cylindrical closed-ended pile near the toe. The aim of the study is to calculate the evolution of the liquefaction zone around the pile for a large number of cycles. A parametric study is carried out to show how the growth of the liquefaction zone depends on the pile displacement amplitude, the relative soil density, the effective stress in the far field and the pore fluid compressibility. © 2013 Springer-Verlag Berlin Heidelberg.

The aim of this article is to provide an overview of current research activities on functional, magnetic nanocomposite materials. After a brief introduction to general strategies for the synthesis of superparamagnetic nanoparticles (NPs), different concepts and state-of-the-art solution chemical methods for their integration into various types of functional, magnetic nanocomposite materials will be reviewed. The focus is on functional materials which are based on discrete magnetic NPs, including multicomponent nanostructures, colloidal nanocrystals, matrix-dispersed composite materials and mesoscaled particles. The review further outlines the magnetic, structural, and surface properties of the materials with regard to application. © 2011 The Royal Society of Chemistry.

Paradies J.,Karlsruhe Institute of Technology
Synthesis | Year: 2011

Advances in the field of [2.2]paracyclophane chemistry are reviewed including syntheses, resolution of enantiomers and application in organic synthesis. Transition-metal catalyzed as well as organocatalytic transformations are presented focusing on the development of [2.2]paracyclophane derived ligands and catalysts. 1 Introduction 2 [2.2]Paracyclophane Syntheses 3 Ligand Design on the Basis of [2.2]Paracyclophane 4 Application in Asymmetric Catalysis 4.1 Addition of Organozinc Reagents to Carbonyl Compounds 4.2 Application of [2.2]Paracyclophane-Derived Phosphines 4.2.1 Hydrogenation Reactions 4.2.2 Transition-Metal-Catalyzed C-C and C-X Bond Formation Employing Planar-Chiral Phosphines 4.2.3 Planar-Chiral Carbenes 4.2.4 [2.2]Paracyclophanes in Organocatalysis 5 Summary.

Hartwig A.,Karlsruhe Institute of Technology
Metal ions in life sciences | Year: 2013

Cadmium is an established human and animal carcinogen. Most evidence is available for elevated risk for lung cancer after occupational exposure; however, associations between cadmium exposure and tumors at other locations including kidney, breast, and prostate may be relevant as well. Furthermore, enhanced cancer risk may not be restricted to comparatively high occupational exposure, but may also occur via environmental exposure, for example in areas in close proximity to zinc smelters. The underlying mechanisms are still a matter of manifold research activities. While direct interactions with DNA appear to be of minor importance, elevated levels of reactive oxygen species (ROS) have been detected in diverse experimental systems, presumably due to an inactivation of detoxifying enzymes. Also, the interference with proteins involved in the cellular response to DNA damage, the deregulation of cell growth as well as resistance to apoptosis appears to be involved in cadmium-induced carcinogenicity. Within this context, cadmium has been shown to disturb nucleotide excision repair, base excision repair, and mismatch repair. Particularly sensitive targets appear to be proteins with zinc-binding structures, present in DNA repair proteins such as XPA, PARP-1 as well as in the tumor suppressor protein p53. Whether or not these interactions are due to displacement of zinc or due to reactions with thiol groups involved in zinc complexation or in other critical positions under realistic exposure conditions remains to be elucidated. Further potential mechanisms relate to the interference with cellular redox regulation, either by enhanced generation of ROS or by reaction with thiol groups involved in the regulation of signaling pathways. Particularly the combination of these multiple mechanisms may give rise to a high degree of genomic instability evident in cadmium-adapted cells, relevant not only for tumor initiation, but also for later steps in tumor development.

Ricca E.,University of Calabria | Brucher B.,Karlsruhe Institute of Technology | Schrittwieser J.H.,University of Graz
Advanced Synthesis and Catalysis | Year: 2011

Multi-enzymatic cascade reactions, i.e., the combination of several enzymatic transformations in concurrent one-pot processes, offer considerable advantages: the demand of time, costs and chemicals for product recovery may be reduced, reversible reactions can be driven to completion and the concentration of harmful or unstable compounds can be kept to a minimum. This review summarizes the developments in multi-enzymatic cascades employed for the asymmetric synthesis of chiral alcohols, amines and amino acids, as well as for C-C bond formation. In addition, a general classification of biocatalytic cascade systems is provided and bioprocess engineering aspects associated with the topic are discussed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ramezani M.,Karlsruhe Institute of Technology
Journal of Emerging Technologies in Web Intelligence | Year: 2011

Social tagging applications allow users to annotate online resources, resulting in a complex network of interrelated users, resources and tags often called a Folksonomy. A folksonomy is often represented as a hyper-graph in which each hyper-edge connects a user, resource and tag. This tripartite hyper-graph is often used by data mining applications to provide services for the user such as tag recommenders. This paper provides an overview on the state of the art of graph-based tag recommendation from a critical perspective. In addition, we suggest improving the existing graph-based tag recommendation techniques by introducing a new model of the folksonomy as a directed graph. © 2011 ACADEMY PUBLISHER.

Kappeler F.,Karlsruhe Institute of Technology | Gallino R.,University of Turin | Gallino R.,National institute for astrophysics | Bisterzo S.,University of Turin | Aoki W.,Japan National Astronomical Observatory
Reviews of Modern Physics | Year: 2011

Nucleosynthesis in the s process takes place in the He-burning layers of low-mass asymptotic giant branch (AGB) stars and during the He- and C-burning phases of massive stars. The s process contributes about half of the element abundances between Cu and Bi in solar system material. Depending on stellar mass and metallicity the resulting s-abundance patterns exhibit characteristic features, which provide comprehensive information for our understanding of the stellar life cycle and for the chemical evolution of galaxies. The rapidly growing body of detailed abundance observations, in particular, for AGB and post-AGB stars, for objects in binary systems, and for the very faint metal-poor population represents exciting challenges and constraints for stellar model calculations. Based on updated and improved nuclear physics data for the s-process reaction network, current models are aiming at an ab initio solution for the stellar physics related to convection and mixing processes. Progress in the intimately related areas of observations, nuclear and atomic physics, and stellar modeling is reviewed and the corresponding interplay is illustrated by the general abundance patterns of the elements beyond iron and by the effect of sensitive branching points along the s-process path. The strong variations of the s-process efficiency with metallicity bear also interesting consequences for galactic chemical evolution. © 2011 American Physical Society.

Klinkhamer F.R.,University of Tokyo | Klinkhamer F.R.,Karlsruhe Institute of Technology
Classical and Quantum Gravity | Year: 2011

It has been suggested that the Newtonian gravitational force may emerge as an entropic force from a holographic microscopic theory. In this framework, the possibility is reconsidered that Newton's gravitational coupling constant G can be derived from the fundamental constants of the underlying microscopic theory. © 2011 IOP Publishing Ltd.

Geist A.,Karlsruhe Institute of Technology
Solvent Extraction and Ion Exchange | Year: 2010

Nitric acid extraction from 0.1 mol/L - 5 mol/L nitric acid into varied volume fractions (5%-100%) of long-chain aliphatic alcohols (1-hexanol, 1-octanol, 2-ethylhexanol, 1-decanol) in alkanes (different kerosenes, n-dodecane, isooctane) was measured. At equal molar alcohol concentration, 1-hexanol, 1-octanol, and 1-decanol extract equal amounts of nitric acid. The amount of nitric acid extracted into 2-ethyl-hexanol is approxmately half compared to 1-octanol. The alkane does not influence nitric acid extraction. Extraction can accurately be calculated taking into account the formation of a species (HNO3)(ROH)2. Due to the change in diluent properties with alcohol volume fraction, conditional equilibrium constants must be used. © Taylor & Francis Group, LLC.

Buchgeister J.,Karlsruhe Institute of Technology
Chemical Engineering and Technology | Year: 2010

The design of environmental-effective energy conversion processes can be provided by exergoenviromental analysis which is a new method supporting the design for environment. It combines an exergy analysis with a life cycle assessment (LCA) to determine thermodynamic efficiency and formation of environmental impacts on plant components. The exergoenvironmental approach is used to assign environmental impacts to all energy and material flows as well as thermodynamic inefficiencies within each process component. The analysis reveals the interdependencies between thermodynamic behavior and environmental impacts and between process components. Presenting an example of electricity production using a high-temperature solid oxide fuel cell (SOFC) with an integrated allothermal biomass gasification process, exergoenvironmental analysis is described and the environmentally most relevant process components are identified. Furthermore, the result of the exergoenvironmental analysis is discussed with regard to utilization for process design and optimization in chemical production. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mereacre V.,Karlsruhe Institute of Technology
Angewandte Chemie - International Edition | Year: 2012

Using 57Fe Mössbauer spectroscopy, three examples of coordination compounds with different topologies containing Fe III and Ln III ions (Dy III and Tb III; see diagram; insets: clusters cores) were analyzed. In the same crystal field environment, Dy and Tb ions show different degrees of anisotropy, which can be qualitatively detected using an indirect method. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lukanidin E.,Danish Cancer Society | Sleeman J.P.,University of Heidelberg | Sleeman J.P.,Karlsruhe Institute of Technology
Seminars in Cancer Biology | Year: 2012

Communication between cancer cells and stromal cells, often mediated by extracellular molecules in the tumor microenvironment, plays a central role in tumorigenesis and metastasis. The establishment of a pro-inflammatory milieu is increasingly recognized as an important consequence of these interactions. The family of S100 Ca2+-binding proteins has been implicated in many aspects of the interaction between cancer cells and stromal cells, and contributes to the formation of an inflammatory tumor microenvironment. Focusing on S100A4, S100A8 and S100A9, in this review we discuss the role these proteins play in primary tumors and in the development of metastases, in particular during the formation of pre-metastatic niches. © 2012 Elsevier Ltd.

Cole J.H.,Karlsruhe Institute of Technology
Journal of Physics A: Mathematical and Theoretical | Year: 2010

The effect of entanglement sudden death (ESD) can arise when entangling interactions convert purely bipartite entangled states into more generally entangled states. As a result, ESD can also be seen as a function of partitioning of the system, not just of time, as the system partitioning defines different (multipartite) entanglement classes. Computing both geometric entanglement hierarchies and the generalization of concurrence allows one to demonstrate that different methods of analysing quantum correlations provide both qualitative and quantitatively different descriptions of two commonly cited examples of ESD. These results follow directly from the inequivalence of entanglement and quantum correlations, the latter of which can exist in a state without the former. © 2010 IOP Publishing Ltd.

Fernandes R.M.,University of Minnesota | Chubukov A.V.,University of Wisconsin - Madison | Schmalian J.,Karlsruhe Institute of Technology
Nature Physics | Year: 2014

Although the existence of nematic order in iron-based superconductors is now a well-established experimental fact, its origin remains controversial. Nematic order breaks the discrete lattice rotational symmetry by making the x and y directions in the iron plane non-equivalent. This can happen because of a regular structural transition or as the result of an electronically driven instability-in particular, orbital order or spin-driven Ising-nematic order. The latter is a magnetic state that breaks rotational symmetry but preserves time-reversal symmetry. Symmetry dictates that the development of one of these orders immediately induces the other two, making the origin of nematicity a physics realization of the 'chicken and egg problem'. In this Review, we argue that the evidence strongly points to an electronic mechanism of nematicity, placing nematic order in the class of correlation-driven electronic instabilities, like superconductivity and density-wave transitions. We discuss different microscopic models for nematicity and link them to the properties of the magnetic and superconducting states, providing a unified perspective on the phase diagram of the iron pnictides. © 2014 Macmillan Publishers Limited.

Nienhaus G.U.,Karlsruhe Institute of Technology | Nienhaus G.U.,University of Illinois at Urbana - Champaign
Angewandte Chemie - International Edition | Year: 2012

Like the battery bunny: The novel photoswitchable fluorescent protein rsEGFP can be cycled between its fluorescent and nonfluorescent states more than a thousand times and is, therefore, a superb marker for high-resolution RESOLFT imaging (RESOLFT=reversible saturable optical fluorescence transition) and data storage applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Haehnlein S.,University of Tubingen | Bayer P.,ETH Zurich | Blum P.,Karlsruhe Institute of Technology
Renewable and Sustainable Energy Reviews | Year: 2010

Shallow geothermal energy (<400 m depth) is used in many countries worldwide, with a rising number of installations over the last decades. The use of ground source heat pump (GSHP) and groundwater heat pump (GWHP) systems results in local temperature anomalies (cold or heat plumes). Since groundwater is used in many countries as source for drinking water a balance between its use and protection has to be found. Therefore, to avoid detrimental environmental impacts it is necessary to define groundwater temperature limits for heating and cooling and minimum distances between such geothermal systems. The aim of the present study is to provide a comprehensive overview of the current international legal status for the use of shallow geothermal energy. Therefore, an international survey was performed using a questionnaire, which was sent to more than 60 countries worldwide. The questionnaire requested information on the corresponding national legislation, temperature limits and minimum distances for GSHP and GWHP systems. The answers to the inquiry showed an extremely heterogeneous outcome. Until now national and legally binding regulations only exist in few countries such as Denmark or Sweden. However, all existing regulations show a wide range for minimum distances (5-300 m) and temperature limits for groundwater. The highest inconsistency was observed for the acceptable temperature change with 3 K in Switzerland to 11 K in France. However, most countries have no legally binding regulations or even guidelines, which highlight the urgent need for further research on the environmental impact and legal management of shallow geothermal installations. © 2010 Elsevier Ltd. All rights reserved.

Kalcsics J.,Karlsruhe Institute of Technology
Computers and Operations Research | Year: 2011

In this paper we discuss the multi-facility location problem on networks with positive and negative weights. As the finite dominating set for the single facility problem does not carry over to the multi-facility problem, we derive a new finite dominating set. To solve the problem, we present a straight-forward algorithm. Moreover, for the problem with just two new facilities, we show how to obtain a more efficient solution procedure by using planar arrangements. We present computational results to underline the efficiency of the improved algorithm and to test some approximations which are based on a reduced candidate set. © 2010 Elsevier Ltd. All rights reserved.

Hofheinz D.,Karlsruhe Institute of Technology
Journal of Cryptology | Year: 2011

The selective decommitment problem can be described as follows: assume that an adversary receives a number of commitments and then may request openings of, say, half of them. Do the unopened commitments remain secure? Although this question arose more than twenty years ago, no satisfactory answer could be presented so far. We answer the question in several ways: 1. If simulation-based security is desired (i.e., if we demand that the adversary's output can be simulated by a machine that does not see the unopened commitments), then security is not provable for noninteractive or perfectly binding commitment schemes via black-box reductions to standard cryptographic assumptions. However, we show how to achieve security in this sense with interaction and a non-black-box reduction to one-way permutations. 2. If only indistinguishability of the unopened commitments from random commitments is desired, then security is not provable for (interactive or noninteractive) perfectly binding commitment schemes, via black-box reductions to standard cryptographic assumptions. However, any statistically hiding scheme does achieve security in this sense. Our results give an almost complete picture when and how security under selective openings can be achieved. Applications of our results include: - Essentially, an encryption scheme must be non-committing in order to achieve provable security against an adaptive adversary. - When implemented with our secure commitment scheme, the interactive proof for graph 3-coloring due to [28] becomes zero-knowledge under parallel composition. On the technical side, we develop a technique to show very general impossibility results for black-box proofs. © International Association for Cryptologic Research 2009.

Fischer J.,Karlsruhe Institute of Technology | Heun V.,Ludwig Maximilians University of Munich
SIAM Journal on Computing | Year: 2011

Given a static array of n totally ordered objects, the range minimum query problem is to build a data structure that allows us to answer efficiently subsequent on-line queries of the form "what is the position of a minimum element in the subarray ranging from i to j?". We focus on two settings, where (1) the input array is available at query time, and (2) the input array is available only at construction time. In setting (1), we show new data structures (a) of size 2n/c(n) -Θ(n lg lg n/c(n) lg n) bits and query time O(c(n)) for any positive integer function c(n) ε O(nε) for an arbitrary constant 0 < ε < 1, or (b) with O(nHk) + o(n) bits and O(1) query time, where Hk denotes the empirical entropy of kth order of the input array. In setting (2), we give a data structure of size 2n+o(n) bits and query time O(1). All data structures can be constructed in linear time and almost in-place. Copyright © by SIAM.

Wacker I.,Karlsruhe Institute of Technology | Schroeder R.R.,University of Heidelberg
Journal of Microscopy | Year: 2013

Summary: In array tomography ordered, ribbon-like assemblies of ultrathin serial sections are deposited on a solid substrate and imaged afterwards. The resulting images are then aligned and reconstructed into a three-dimensional representation of the object. Depending on the preparation and labelling regime, different imaging modalities can be applied. When using light microscopy, the labelling with fluorescent markers would be the obvious choice, whereas the imaging in a scanning electron microscope would require impregnation with heavy metals. Depending on preparative constraints, the combination of diverse imaging modalities or truly correlative imaging is possible. © 2013 Royal Microscopical Society.

Fischer J.,Karlsruhe Institute of Technology
Theoretical Computer Science | Year: 2011

Let A be a static array storing n elements from a totally ordered set. We present a data structure of optimal size at most nlog2(3+22)+o(n) bits that allows us to answer the following queries on A in constant time, without accessing A: (1) previous smaller value queries, where given an index i, we wish to find the first index to the left of i where A is strictly smaller than at i, and (2) next smaller value queries, which search to the right of i. As an additional bonus, our data structure also allows one to answer a third kind of query: given indices i

Send R.,Karlsruhe Institute of Technology | Valsson O.,University of Twente | Filippi C.,University of Twente
Journal of Chemical Theory and Computation | Year: 2011

The simplest cyanine dye series [H2N(CH)nNH 2]+ with n = 1, 3, 5, 7, and 9 appears to be a challenge for all theoretical excited-state methods since the experimental spectra are difficult to predict and the observed deviations cannot be easily explained with standard arguments. We compute here the lowest vertical excitation energies of these dyes using a variety of approaches, namely, complete active space second-order perturbation theory (CASPT2), quantum Monte Carlo methods (QMC), coupled cluster linear response up to third approximate order (CC3), and various flavors of time-dependent density functional theory (TDDFT), including the recently proposed perturbative correction scheme (B2PLYP). In our calculations, all parameters such as basis set, active space, and geometry dependence are carefully analyzed. We find that all wave function methods give reasonably close excitation energies, with CASPT2 yielding the lowest values, and that the B2PLYP scheme gives excitations in satisfactory agreement with CC3 and DMC, significantly improving on the generalized gradient and hybrid approximations. Finally, to resolve the remaining discrepancy between predicted excitation energies and experimental absorption spectra, we also investigate the effect of excited-state relaxation. Our results indicate that a direct comparison of the experimental absorption maxima and the theoretical vertical excitations is not possible due to the presence of nonvertical transitions. The apparent agreement of earlier CASPT2 calculations with experiments was an artifact of the choice of active space and the use of an older definition of the zero-order Hamiltonian. © 2011 American Chemical Society.

Fuchs B.,Karlsruhe Institute of Technology
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2012

High and ultra-high energy cosmic rays hitting the Earths atmosphere cause extensive air showers (EAS). In recent years, these cosmic rays have been extensively studied at the Pierre Auger Observatory in Argentina. The EAS mainly consist of charged particles, especially electrons and positrons, which cause electro-magnetic emission in the MHz range by interaction with the Earths magnetic field. To measure this radio emission, AERA, the Auger Engineering Radio Array, was deployed in October 2010 and commenced regular data acquisition in April 2011. AERA was designed as an engineering array for technology and methodology development towards future large-scale radio arrays. It will allow studies on the radio emission mechanism and the physics capabilities of the detection technique. AERAs unique site within the surface detector array (SD) of the Pierre Auger Observatory provides the possibility of coincident hybrid and super-hybrid EAS detection especially in overlap with the fluorescence telescopes Coihueco and HEAT. Besides a description of the setup, we present an overview of analyses of commissioning data taken between November 2010 and April 2011. Also, we show the first hybrid and self-triggered events detected with AERA in April 2011. © 2012 Elsevier B.V.

Steinbruck M.,Karlsruhe Institute of Technology
Journal of Nuclear Materials | Year: 2010

Extensive series of test were performed of the degradation of boron carbide absorber rods and the oxidation of the resultant absorber melts. Various types of control rod segments made of commercial materials used in French 1300 MW PWRs were investigated in the temperature range between 800 °C and 1700 °C in a steam atmosphere. The gaseous reaction products were analyzed quantitatively by mass spectroscopy for evaluation of the oxidation rates. Extensive post-test examinations were performed by light microscopy, scanning electron microscopy as well as EDX and Auger spectroscopy. Rapid melt formation due to eutectic interactions of stainless steel (cladding tube) and B 4C, on the one hand, and steel and Zir-caloy-4 (guide tube), on the other hand, was observed at temperatures above 1250 °C. Complex multi-component, multi-phase melts were produced. ZrO 2 oxide scale on the outside kept the melt within the guide tube, thus preventing its early relocation and oxidation. Rapid oxidation of the absorber melts and remaining boron carbide pellets took place after failure of the protective oxide shell above 1450 °C. Only very little methane was produced in these tests which is of interest in fission product gas chemistry because of the production of organic iodine. © 2010 Elsevier B.V. All rights reserved.

Pak A.,Karlsruhe Institute of Technology
Journal of Physics: Conference Series | Year: 2012

We describe three algorithms for computer-aided symbolic multi-loop calculations that facilitated some recent novel results. First, we discuss an algorithm to derive the canonical form of an arbitrary Feynman integral in order to facilitate their identification. Second, we present a practical solution to the problem of multi-loop analytical tensor reduction. Finally, we discuss the partial fractioning of polynomials with external linear relations between the variables. All algorithms have been tested and used in real calculations.

Nollenburg M.,Karlsruhe Institute of Technology | Wolff A.,University of Wurzburg
IEEE Transactions on Visualization and Computer Graphics | Year: 2011

Metro maps are schematic diagrams of public transport networks that serve as visual aids for route planning and navigation tasks. It is a challenging problem in network visualization to automatically draw appealing metro maps. There are two aspects to this problem that depend on each other: the layout problem of finding station and link coordinates and the labeling problem of placing nonoverlapping station labels. In this paper, we present a new integral approach that solves the combined layout and labeling problem (each of which, independently, is known to be NP-hard) using mixed-integer programming (MIP). We identify seven design rules used in most real-world metro maps. We split these rules into hard and soft constraints and translate them into an MIP model. Our MIP formulation finds a metro map that satisfies all hard constraints (if such a drawing exists) and minimizes a weighted sum of costs that correspond to the soft constraints. We have implemented the MIP model and present a case study and the results of an expert assessment to evaluate the performance of our approach in comparison to both manually designed official maps and results of previous layout methods. © 2011 IEEE.

Paradies J.,Karlsruhe Institute of Technology
Synlett | Year: 2013

The frustrated Lewis pair (FLP) catalyzed hydrogenation of organic molecules is discussed. The saturation of polarized double bonds by FLP can be described as the nucleophilic addition of hydrides to the polar double bond prior to proton transfer. In contrast, the hydrogenation of olefins proceeds first by protonation forming a transient carbocation, which is subsequently attacked by the hydride. Both processes give rise for efficient conversion of unsaturated organic compounds by a metal-free methodology employing molecular hydrogen. © Georg Thieme Verlag Stuttgart · New York.

Hartmann P.,Justus Liebig University | Bender C.L.,Justus Liebig University | Vracar M.,Justus Liebig University | Vracar M.,Karlsruhe Institute of Technology | And 4 more authors.
Nature Materials | Year: 2013

In the search for room-temperature batteries with high energy densities, rechargeable metal-air (more precisely metal-oxygen) batteries are considered as particularly attractive owing to the simplicity of the underlying cell reaction at first glance. Atmospheric oxygen is used to form oxides during discharging, which - ideally - decompose reversibly during charging. Much work has been focused on aprotic Li-O2 cells (mostly with carbonate-based electrolytes and Li2O2 as a potential discharge product), where large overpotentials are observed and a complex cell chemistry is found. In fact, recent studies evidence that Li-O2 cells suffer from irreversible electrolyte decomposition during cycling. Here we report on a Na-O2 cell reversibly discharging/charging at very low overpotentials (< 200 mV) and current densities as high as 0.2 mA cm-2 using a pure carbon cathode without an added catalyst. Crystalline sodium superoxide (NaO2) forms in a one-electron transfer step as a solid discharge product. This work demonstrates that substitution of lithium by sodium may offer an unexpected route towards rechargeable metal-air batteries. © 2013 Macmillan Publishers Limited. All rights reserved.

Boguslawski K.,ETH Zurich | Jacob C.R.,Karlsruhe Institute of Technology | Reiher M.,ETH Zurich
Journal of Chemical Theory and Computation | Year: 2011

Iron nitrosyl complexes are a particularly challenging case for density functional theory. In particular, for the low-spin state, different exchange-correlation functionals yield very different spin densities [Conradie, J.; Ghosh, A.J. Phys. Chem. B 2007, 111, 12621-12624]. Here, we investigate the origin of these differences in detail by analyzing the Kohn-Sham molecular orbitals. Furthermore, to decide which exchange-correlation functionals yield the most accurate spin densities, we make comparisons to CASSCF calculations. To ensure that the spin densities are converged with respect to the size of the active space, this comparison is performed for [Fe(NO)]2+ as a model system. We find that none of the investigated exchange-correlation functionals are able to reproduce the CASSCF spin densities accurately. © 2011 American Chemical Society.

Vehlow J.,Karlsruhe Institute of Technology
Reviews in Environmental Science and Biotechnology | Year: 2012

Since 1977 dioxins were detected in fly ashes from waste incineration plants; this class of compounds is of major importance concerning the acceptance of this technology. Extended research and development revealed in short time the main formation mechanism of dioxins, the importance of good combustion control, the influence of halogens and sulphur, and paved the way for strategies for minimisation of formation, and efficient abatement. The main steps in this development as well as the current situation are described. © 2012 Springer Science+Business Media B.V.

Nierling L.,Karlsruhe Institute of Technology
Ecological Economics | Year: 2012

The decommodification of work activity is central for conceiving work from a degrowth perspective. Yet personal dependence on paid work is very high, whereas unpaid work activity, such as providing care, community service and subsistence, continues to be neglected by individuals and society. By using the analytical approach related to recognition as employed by Axel Honneth, I argue on the basis of empirical findings that unpaid work can play a significant role in one's personal well-being at the individual level. With regard to the transition process towards a society of degrowth, however, a key seems to be a change in the normative paradigm concerning work at the individual level. © 2012.

Delling D.,Karlsruhe Institute of Technology
Algorithmica (New York) | Year: 2011

In recent years, many speed-up techniques for Dijkstra's algorithm have been developed that make the computation of shortest paths in static road networks a matter of microseconds. However, only few of those techniques work in time-dependent networks which, unfortunately, appear quite frequently in reality: Roads are predictably congested by traffic jams, and efficient timetable information systems rely on time-dependent networks. Hence, a fast technique for routing in such networks is needed. In this work, we present an efficient time-dependent route planning algorithm. It is based on our recently introduced SHARC algorithm, which we adapt by augmenting its basic ingredients such that correctness can still be guaranteed in a time-dependent scenario. As a result, we are able to efficiently compute exact shortest paths in time-dependent continental-sized transportation networks, both of roads and of railways. It should be noted that time-dependent SHARC was the first efficient algorithm for time-dependent route planning. © 2009 Springer Science+Business Media, LLC.

Chalons G.,Karlsruhe Institute of Technology | Semenov A.,University of Savoy
Journal of High Energy Physics | Year: 2011

We have computed the loop-induced processes of neutralino annihilation into two photons and, for the first time, into a photon and a Z0 boson in the framework of the NMSSM. The photons produced from these radiative modes are monochromatic and possess a clear "smoking gun" experimental signature. This numerical analysis has been done with the help of the SloopS code, initially developed for automatic one-loop calculation in the MSSM. We have computed the rates for different benchmark points coming from SUGRA and GMSB soft SUSY breaking scenarios and compared them with the MSSM. We comment on how this signal can be enhanced, with respect to the MSSM, especially in the low mass region of the neutralino. We also discuss the possibility of this observable to constrain the NMSSM parameter space, taking into account the latest limits from the FERMI collaboration on these two modes.

Grosse M.,Karlsruhe Institute of Technology
Nuclear Technology | Year: 2010

Isothermal and transient steam oxidation kinetics of the fuel rod cladding materials Duplex, M5™, E110, and Zircaloy-4 (Zry-4) were determined in separate-effect tests at various temperatures between 1073 and 1673 K. All materials show parabolic time dependence at all temperatures, at least at the beginning of the oxidation. The temperature dependence of the oxidation rate isArrheniuslike. All materials investigated show changes in the activation energy of the steam oxidation connected with the tetragonal-monoclinicphase transformation in the oxide. The temperatures of these changes differ between the Zr-Sn (Zry-4, Duplex: 1223 to 1273K) and the Zr-Nb alloys (M5™, EUO: 1273 to 1323K). At temperatures below this phase transition, parts of the oxide layer can spall after longer oxidation times. It is known as the so-called "breakaway effect. " This effect occurs in Zry-4 and E110, whereas it was not detected in Duplex and M5™. The breakaway effect results in nearly linear oxidation kinetics. The width of the temperature range and the morphology of the spoiled oxide parts differ significantly between Zry-4 and E110. For Zry-4, the breakaway effect was found only at temperatures between 1233 and 1313 K. The spoiling of the oxide layer at E110 was detected between 1073 and 1313 K. This wide temperature range also affects the transient steam oxidation behavior. For heating rates below 0.1 K/s, a stronger oxidation was found than expected for parabolic oxidation behavior. The oxide parts spoiled from E110 specimens are much finer than the particles after breakaway from Zry-4.

Wang T.,CAS Changchun Institute of Applied Chemistry | Wang T.,University of Chinese Academy of Sciences | Bai J.,CAS Changchun Institute of Applied Chemistry | Jiang X.,CAS Changchun Institute of Applied Chemistry | And 2 more authors.
ACS Nano | Year: 2012

It is well-known that nanomaterials are capable of entering living cells, often by utilizing the cells' endocytic mechanisms. Passive penetration of the lipid bilayer may, however, occur as an alternative process. Here we have focused on the passive transport of small nanoparticles across the plasma membranes of red blood cells, which are incapable of endocytosis. By using fluorescence microscopy, we have observed that zwitterionic quantum dots penetrate through the cell membranes so that they can be found inside the cells. The penetration-induced structural changes of the lipid bilayer were explored by surface-enhanced infrared absorption spectroscopy and electrochemistry studies of model membranes prepared on solid supports with lipid compositions identical to those of red blood cell membranes. A detailed analysis of the infrared spectra revealed a markedly enhanced flexibility of the lipid bilayers in the presence of nanoparticles. The electrochemistry data showed that the overall membrane structure remained intact; however, no persistent holes were formed in the bilayers. © 2012 American Chemical Society.

Kuhn M.,Karlsruhe Institute of Technology
Journal of Chemical Theory and Computation | Year: 2014

The correlation energy within the two-component random phase approximation accounting for spin-orbit effects is derived. The resulting plasmon equation is rewritten - analogously to the scalar relativistic case - in terms of the trace of two Hermitian matrices for (Kramers-restricted) closed-shell systems and then represented as an integral over imaginary frequency using the resolution of the identity approximation. The final expression is implemented in the TURBOMOLE program suite. The code is applied to the computation of equilibrium distances and vibrational frequencies of heavy diatomic molecules. The efficiency is demonstrated by calculation of the relative energies of the Oh-, D4h-, and C5v-symmetric isomers of Pb6. Results within the random phase approximation are obtained based on two-component Kohn-Sham reference-state calculations, using effective-core potentials. These values are finally compared to other two-component and scalar relativistic methods, as well as experimental data. © 2014 American Chemical Society.

Smirnov A.V.,Karlsruhe Institute of Technology
Computer Physics Communications | Year: 2014

The goal of this paper is to present a new major release of the program FIESTA (Feynman Integral Evaluation by a Sector decomposiTion Approach). This version presents features like cluster-parallelization, new asymptotic expansion algorithms, calculations in physical regions, new sector-decomposition strategies, as well as multiple speed, memory, and stability improvements. © 2014 Elsevier B.V. All rights reserved.

Sander M.,Karlsruhe Institute of Technology
IEEE Transactions on Applied Superconductivity | Year: 2011

A new energy storage concept is proposed that combines the use of liquid hydrogen (LH2) with Superconducting Magnetic Energy Storage (SMES). The anticipated increase of the contribution of intermittent renewable power plants like wind or solar farms will substantially increase the need for balancing demands and supplies from seconds to several hours or even days. LH2 with its high volumetric energy density is the prime candidate for large scale stationary energy storage but balancing load or supply fluctuations with hydrogen alone is unrealistic due to the losses related to the re-conversion into electricity and also due to the response times of the flow control. To operate the hydrogen part more steadily some short-term electrical energy storage will be needed. Here a SMES based on High Temperature Superconductors (HTS) is proposed for this purpose which could be operated in the LH2 bath. With this approach the cryogenics-related costs for the SMES are widely cut. The concept is introduced. Simple simulations on the buffering behavior and comparisons of different plant types are presented. © 2010 IEEE.

Robust experiments that cover a wide range of chemical shift offsets and J-couplings are highly desirable for a multitude of applications in small molecule NMR spectroscopy. Many attempts to improve individual aspects of the robustness of pulse sequence elements based on rational and numerical design have been reported, but a general optimization strategy to cover all necessary aspects for a fully robust sequence is still lacking. In this article, a viable optimization strategy is introduced that covers a defined range of couplings, offsets, and B(1)-field inhomogeneities (COB) in a time-optimal way. Individual components of the optimization strategy can be optimized in any adequate way. As an example for the COB approach, we present the (1)H -(13)C-COB-INEPT with transfer of approximately 99% over the full carbon and proton bandwidth and (1)J(CH) -couplings in the range of 120-250 Hz, which have been optimized using efficient algorithms derived from optimal control theory. The theoretical performance is demonstrated in a number of corresponding COB-HSQC experiments. Copyright © 2012 John Wiley & Sons, Ltd.

With polyurethane (PU), a novel alignment medium for organic solvents is introduced and characterized, which is very robust and easy to produce on a large scale. Linear PU already constitutes an elastomer gel with several solvents based on its ability to form hydrogen bonds. Covalent cross-linking of the polymer with accelerated electrons provides an alignment medium with different properties. However, PU exhibits a number of undesired polymer signals in corresponding spectra, which ideally have to be removed spectroscopically. Within this context, we demonstrate the applicability of diffusion-filtered experiments for removal of the polymer signals. Example spectra for the usefulness of PU alignment media are provided for the common test molecules strychnine and norcamphor. Copyright © 2012 John Wiley & Sons, Ltd.

Tzvetkova P.,Karlsruhe Institute of Technology
Magnetic resonance in chemistry : MRC | Year: 2012

The configurational analysis of organic compounds is an important application for high resolution NMR spectroscopy. In the present study, a tetra-substituted pyrrolidine with four chiral carbon atoms is analyzed using classical methods based on (3) J and NOE data in solution and compared and verified with recently introduced alternative approaches via residual dipolar couplings (RDCs) in two weak anisotropic alignment media. The molecule shows sufficient rigidity in the five-membered ring for the configurational characterization with the various techniques. However, the flexibility caused by the many freely rotating bonds potentially poses problems for the interpretation of data. It is shown that RDCs measured in poly-γ-benzyl-l-glutamate and a stretched polydimethylsiloxane gel provide useful information for the distinction of diastereomers, but the success varies with the data interpretation strategy used. Although a general improvement of corresponding correlation factors is observed when limiting data to a subset of dipolar couplings directly connected to the central ring, the distinction power is reduced because of the smaller number of RDCs available for potential model falsification. Singular value decomposition for fitting experimental RDCs is able to distinguish in most cases the correct from incorrect configurations, but the differences in correlation factors can be relatively small. Surprisingly, predicting RDCs using the rod model as implemented in PALES gives best results in distinguishing the eight possible diastereomers. It is also found that the use of proton-phosphorus and carbon-phosphorus RDCs helps with the configurational analysis of the model compound. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.

Halimeh J.C.,Ludwig Maximilians University of Munich | Wegener M.,Karlsruhe Institute of Technology
Optics Express | Year: 2013

Carpet or ground-plane invisibility cloaks hide an object in reflection and inhibit transmission experiments by construction. This concept has significantly reduced the otherwise demanding material requirements and has hence enabled various experimental demonstrations. In contrast, free-space invisibility cloaks should work in both reflection and transmission. The fabrication of omnidirectional three-dimensional freespace cloaks still poses significant challenges. Recently, the idea of the carpet cloak has been carried over to experiments on unidirectional freespace invisibility cloaks that only work perfectly for one particular viewing direction and, depending on the design, also for one linear polarization of light only. Here, by using photorealistic ray tracing, we visualize the performance of four types of such unidirectional cloaks in three dimensions for different viewing directions and different polarizations of light, revealing virtues and limitations of these approaches in an intuitive manner. © 2013 Optical Society of America.

Patyk A.,Karlsruhe Institute of Technology
Journal of Electronic Materials | Year: 2010

Energy saving in power generation, industry, transport, and residential applications by using waste heat with thermoelectrics (TE) may be important for an environmentally sound and sustainable energy system. It is probable that operable TE generators (TEG) will be developed for numerous applications and will save energy and reduce CO 2 emissions from plants. However, the environmental profile of a technology is not sufficiently described by just the energy and CO 2 inputs and outputs of the core process. Necessary preceding and subsequent processes, other environmental impacts, and competing technologies have to be considered as well. Furthermore, sustainability covers aspects beyond environmental soundness. So far, comprehensive studies on TE and the environment/sustainability have not been available. In this paper, the following selected aspects are discussed: resource availability, specific energy consumption of TEG production, specific energy and CO 2 savings in different application fields by TE and competing technologies, and the global potential of TE. © 2009 TMS.

Klinkhamer F.R.,Karlsruhe Institute of Technology
Modern Physics Letters A | Year: 2014

Certain exact solutions of the Einstein field equations over nonsimply-connected manifolds are reviewed. These solutions are spherically symmetric and have no curvature singularity. They provide a regularization of the standard Schwarzschild solution with a curvature singularity at the center. Spherically symmetric collapse of matter in 4 may result in these nonsingular black-hole solutions, if quantum-gravity effects allow for topology change near the center or if nontrivial topology is already present as a remnant from a quantum spacetime foam. © 2014 World Scientific Publishing Company.

Eder R.,Karlsruhe Institute of Technology
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

The variational cluster approximation (VCA) is applied to the calculation of thermodynamical quantities and single-particle spectra of LaCoO3. Trial self-energies and the numerical value of the Luttinger-Ward functional are obtained by exact diagonalization of a CoO6 cluster. The VCA correctly predicts LaCoO3 as a paramagnetic insulator, and a gradual and relatively smooth increase in the occupation of high-spin Co3+ ions causes the temperature dependence of entropy and magnetic susceptibility. The single-particle spectral function agrees well with experiment; the experimentally observed temperature dependence of photoelectron spectra is reproduced satisfactorily. Remaining discrepancies with experiment highlight the importance of spin-orbit coupling and local lattice relaxation. © 2010 The American Physical Society.

Bahr H.,Karlsruhe Institute of Technology | Hanssen R.F.,Technical University of Delft
Journal of Geodesy | Year: 2012

An approach to improve orbital state vectors by orbit error estimates derived from residual phase patterns in synthetic aperture radar interferograms is presented. For individual interferograms, an error representation by two parameters is motivated: the baseline error in cross-range and the rate of change of the baseline error in range. For their estimation, two alternatives are proposed: a least squares approach that requires prior unwrapping and a less reliable gridsearch method handling the wrapped phase. In both cases, reliability is enhanced by mutual control of error estimates in an overdetermined network of linearly dependent interferometric combinations of images. Thus, systematic biases, e. g., due to unwrapping errors, can be detected and iteratively eliminated. Regularising the solution by a minimum-norm condition results in quasi-absolute orbit errors that refer to particular images. For the 31 images of a sample ENVISAT dataset, orbit corrections with a mutual consistency on the millimetre level have been inferred from 163 interferograms. The method itself qualifies by reliability and rigorous geometric modelling of the orbital error signal but does not consider interfering large scale deformation effects. However, a separation may be feasible in a combined processing with persistent scatterer approaches or by temporal filtering of the estimates. © 2012 Springer-Verlag.

Thumm M.,Karlsruhe Institute of Technology
IEEE Transactions on Plasma Science | Year: 2011

The prototype of the Japan 170-GHz ITER gyrotron holds the energy world record of 2.88 GJ (0.8 MW, 3600 s and 1 MW, 800 s) and the efficiency record of 57%, whereas the Russian 170-GHz ITER prototype tube achieved 0.8 MW with a pulse duration of 800 s at 55% efficiency and 1 MW at 280 s and 53%. The record parameters of the European megawatt-class 140-GHz gyrotron for the stellarator Wendelstein W7-X are as follows: 0.92-MW output power at 1800-s pulse duration, nearly 45% efficiency, and 97.5% Gaussian mode purity. These gyrotrons employ a cylindrical cavity, a quasi-optical output coupler, a synthetic diamond window, and a single-stage depressed collector (SDC) for energy recovery. In order to reduce the costs of the ITER 24-MW 170-GHz ECH&CD system, 2-MW millimeter-wave power per gyrotron tube is desirable. Cylindrical gyrotron cavities are not suitable for the 2-MW power regime because of high ohmic wall losses and mode competition problems. However, in coaxial cavities, the existence of the longitudinally corrugated inner conductor reduces the problem of mode competition, thus allowing one to use even higher order modes with lower ohmic attenuation than in cylindrical cavities. Synthetic diamond windows with a transmission capability of 2-MW CW are feasible. A 2-MW CW 170-GHz coaxial-cavity gyrotron for ECH&CD in ITER is under development in cooperation with European research institutions (EGYC, collaboration among the CRPP, Switzerland, the KIT, Germany, the HELLAS, Greece, the CNR, Italy, and the ENEA, Italy). At the Karlsruhe Institute of Technology (KIT), the short-pulse (1-ms) preprototype tube delivered 2.2 MW at 30% efficiency (without SDC) with 96% Gaussian output mode purity. Design studies for a 4-MW 170-GHz coaxial-cavity gyrotron with two synthetic diamond output windows and two 2-MW millimeter-wave output beams for future fusion reactors are currently being performed at KIT. The availability of sources with fast frequency tunability would permit the use of simple fixed nonsteerable mirror antennas for local current drive experiments and plasma stabilization. IAP Nizhny Novgorod develops in collaboration with IPP Garching and KIT an industrial multifrequency 1-MW gyrotron with approximately 50% efficiency (SDC). A four-frequency tube (105, 117, 127, and 140 GHz) delivered 0.8 MW at 105 GHz and 0.95 MW at 140 GHz in 10-s pulses. After the installation of a broadband diamond window, this gyrotron will be operated also at the two intermediate frequencies. © 2011 IEEE.

Platzer S.,German Electron Synchrotron | Gieseke S.,Karlsruhe Institute of Technology
European Physical Journal C | Year: 2012

We report on the implementation of a coherent dipole shower algorithm along with an automated implementation for dipole subtraction and for performing powheg- and mc@nlo-type matching to next-to-leading order (NLO) calculations. Both programs are implemented as add-on modules to the event generator Herwig++. A preliminary tune of parameters to data acquired at LEP, HERA and Drell-Yan pair production at the Tevatron has been performed, and we find an overall very good description which is slightly improved by the NLO matching. © 2012 The Author(s).

Basse C.W.,Karlsruhe Institute of Technology
Current Opinion in Microbiology | Year: 2010

Faithful inheritance of mitochondria is essential for growth and development. Uniparental inheritance of mitochondria is a common phenomenon in sexual eukaryotes and has been reported for numerous fungal species. Uniparental inheritance is a genetically regulated process, aimed to gain a homoplasmic state within cells, and this is often associated with selective elimination of one parental mitochondria population. This review will focus on recent developments in our understanding of common and specified regulatory circuits of selective mitochondrial inheritance during sexual development. It further refers to the influence of mitochondrial fusion on generation of recombinant mitochondrial DNA molecules. The latter aspect appears rather exciting in the context of intron homing and could bring a new twist to the debate on the significance of uniparental inheritance. The emergence of genome-wide studies offers new perspectives to address potential relationships between uniparental inheritance, vegetative inheritance and last but not least cellular scavenging systems to dispose of disintegrated organelles. © 2010 Elsevier Ltd.

Poganietz W.-R.,Karlsruhe Institute of Technology
Biomass and Bioenergy | Year: 2012

First-generation biofuels are often challenged over their potentially adverse impact on food prices. Biofuels that use nonfood biomass such as lignocellulose are being promoted to ease the conflict between fuels and food. However, their complex processes mean that the total costs of lignocellulosic ethanol may be high in comparison. This might undermine the economic soundness of plans for its use.Another potential advantage of lignocellulosic ethanol is seen in an enhanced contribution to a reduction in greenhouse gas emissions. Yet the increasing attractiveness of lignocellulosic biofuels may also lead to changes in land use that induce additional carbon emissions. For this reason, the environmental impacts of such plans are not straightforward and depend on the affected category of land.The objective of this paper is to compare the economic perspectives and environmental impact of lignocellulosic ethanol with food-based ethanol taking into account market constraints and policy measures. The analysis of the environmental impact focuses on carbon dioxide emissions.In the medium run, i.e., by 2020, lignocellulosic ethanol could enter the gasoline market, crowding out inter alia food-based ethanol. In terms of carbon dioxide emissions, lignocellulosic ethanol seems to be environmentally desirable in each of the analyzed cases. The findings depend crucially on the market conditions, which are influenced inter alia by crude oil, the exchange rate, and technology conditions. © 2011 Elsevier Ltd.

Hartmann F.,Karlsruhe Institute of Technology
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

Semiconductor sensors have been around since the 1950s and today, every high energy physics experiment has one in its repertoire. In Lepton as well as Hadron colliders, silicon vertex and tracking detectors led to the most amazing physics and will continue doing so in the future. This contribution tries to depict the history of these devices exemplarily without being able to honor all important developments and installations. The current understanding of radiation damage mechanisms and recent R&D topics demonstrating the future challenges and possible technical solutions for the SLHC detectors are presented. Consequently semiconductor sensor candidates for an LHC upgrade and a future linear collider are also briefly introduced. The work presented here is a collage of the work of many individual silicon experts spread over several collaborations across the world. © 2010 Elsevier B.V. All rights reserved.

Worner M.,Karlsruhe Institute of Technology
Chemical Engineering Science | Year: 2010

For microfluidic applications the residence time distribution (RTD) of laminar flow in rectangular channels is of interest. The exact velocity profile for this type of flow consists of an infinite series and does not allow analytical evaluation of the RTD curve. In this paper we adopt a simpler binomial product profile which was proposed in literature and serves as good approximation. This allows us to determine in an analytical manner approximate expressions for the diffusion-free RTD of fully developed laminar flow in a straight rectangular channel of arbitrary aspect ratio. Since the evaluation of this RTD is computationally elaborate because it involves the Gauss hypergeometric function, we fit it by an empirical model which is suitable for engineering applications. We find that for a Newtonian fluid there is a narrowing of the RTD as the aspect ratio decreases from unity (square channel) to zero (parallel plates). We investigate the range of applicability of the diffusion-free RTD and show that it is a good estimation for liquids in a certain range of Reynolds numbers. The actual limits of this range depend on the Schmidt number and on the aspect ratio and length-to-hydraulic-diameter ratio of the channel. © 2010 Elsevier Ltd. All rights reserved.

Szalkowski A.M.,Karlsruhe Institute of Technology | Schmid C.D.,Swiss Tropical and Public Health Institute
Briefings in Bioinformatics | Year: 2011

The current understanding of the regulation of transcription does not keep the pace with the spectacular advances in the determination of genomic sequences. Chromatin immunoprecipitation followed by massively parallel sequencing (ChIP-seq) promises to give better insight into transcription regulation by locating sites of protein-DNA interactions. Such loci of putative interactions can be inferred from the genome-wide distributions of ChIP-seq data by peak-calling software. The analysis of ChIP-seq data critically depends on this step and a multitude of these peak-callers have been deployed in the recent years. A recent study reported severe variation among peak-calling results.Yet, peak-calling still lacks systematic quantitative benchmarking.Here, we summarize benchmarking efforts and explain potential drawbacks of each benchmarking method. © The Author 2010. Published by Oxford University Press.

Bonfante P.,CNR Plant Protection Institute | Requena N.,Karlsruhe Institute of Technology
Current Opinion in Plant Biology | Year: 2011

The arbuscular mycorrhizal symbiosis that involves most plants and Glomeromycota fungi is the result of a complex exchange of molecular information, which commences before the partners are in physical contact. On the one hand, plants release soluble factors, including strigolactones that activate both the metabolism and branching of the fungal partners. On the other hand, fungi use compounds that trigger the signaling transduction pathways that are required for the symbiotic modus of plant cells. Here we describe some of the recent discoveries regarding the fungal molecules involved in rhizospheric conversation, and the way in which they are perceived by their hosts. We conclude that similar signaling molecules may have different meanings, depending on the context. However, at the end, specificity must be maintained to ensure appropriate partners enter symbiosis. © 2011 Elsevier Ltd.

Werle P.,Karlsruhe Institute of Technology
Applied Physics B: Lasers and Optics | Year: 2011

Spectroscopic techniques are increasingly used for field laser applications in industry and research. Under field conditions complex gas sensors cannot be considered as stable and therefore drift characterization is a key issue to distinguish between sample data and sensor drift. In this paper the history of von Neumann's two-sample variance and Allan variance stability investigations in the field of frequency metrology and the relationship to wavelet analysis are reviewed. The concept has been used to characterize accuracy and precision of spectroscopic data in the time domain and practical guidelines for the interpretation of σ/τ plots are presented. Two topics relevant for spectroscopic measurements are discussed: First, the optical fringe effect, which is present in any spectrometer, limits the precision and accuracy of spectroscopic measurements by forming time dependent background structures superimposed to the signal under investigation. The two-sample variance is used to characterize optical etalons and long-term drift using σ/τ plots. Second, the short-term instrument stability characteristic in the presence of atmospheric turbulence is discussed. This is important for laser-based gas monitors measuring the turbulent transport of trace gases between the biosphere and the atmosphere using the eddy-covariance technique. It will be shown how the spectral characteristics of turbulence in the Kolmogorov inertial subrange can be identified in the time domain and how the effect of optical fringes can be separated from atmospheric signals. © 2010 Springer-Verlag.

Solares S.D.,University of Maryland University College | Holscher H.,Karlsruhe Institute of Technology
Nanotechnology | Year: 2010

A spectral analysis method has been recently introduced by Stark et al (2002 Proc. Natl Acad. Sci. USA 99 8473-8) and implemented by Sahin et al (2007 Nat.Nanotechnol.2 507-14) using a T-shaped cantilever design, the torsional harmonic cantilever (THC), which is capable of performing simultaneous tapping-mode atomic force microscopy imaging and force spectroscopy. Here we report on numerical simulations of the THC system using a simple dual-mass flexural-torsional model, which is applied in combination with Fourier data processing software to illustrate the spectroscopy process for quality factors corresponding to liquid, air and vacuum environments. We also illustrate the acquisition of enhanced topographical images and deformed surface contours under the application of uniform forces, and compare the results to those obtained with a previously reported linear dual-spring-mass model. © 2010 IOP Publishing Ltd.

Borie E.,Karlsruhe Institute of Technology
Annals of Physics | Year: 2012

In connection with recent and proposed experiments, and new theoretical results, my previous calculations of the Lamb shift in muonic hydrogen will be reviewed and compared with other work. In addition, numerical results for muonic deuterium and helium will be presented. Some previously neglected (but very small) effects are included. © 2011 Elsevier Inc.

Pierog T.,Karlsruhe Institute of Technology
Journal of Physics: Conference Series | Year: 2013

Currently the uncertainty in the prediction of shower observables for different primary particles and energies is dominated by differences between hadronic interaction models. The LHC data on minimum bias measurements can be used to test Monte Carlo generators and these new constrains will help to reduce the uncertainties in air shower predictions. In this article, after a short introduction on air showers we will show the results of the comparison between the updated version of high energy hadronic interaction models with LHC data. Results for air shower simulations and their consequence on the comparison with air shower data will be discussed.

Huege T.,Karlsruhe Institute of Technology
Physics Reports | Year: 2016

In 1965 it was discovered that cosmic ray air showers emit impulsive radio signals at frequencies below 100 MHz. After a period of intense research in the 1960s and 1970s, however, interest in the detection technique faded almost completely. With the availability of powerful digital signal processing techniques, new attempts at measuring cosmic ray air showers via their radio emission were started at the beginning of the new millennium. Starting with modest, small-scale digital prototype setups, the field has evolved, matured and grown very significantly in the past decade. Today's second-generation digital radio detection experiments consist of up to hundreds of radio antennas or cover areas of up to 17 km2. We understand the physics of the radio emission in extensive air showers in detail and have developed analysis strategies to accurately derive from radio signals parameters which are related to the astrophysics of the primary cosmic ray particles, in particular their energy, arrival direction and estimators for their mass. In parallel to these successes, limitations inherent in the physics of the radio signals have also become increasingly clear. In this article, we review the progress of the past decade and the current state of the field, discuss the current paradigm of the radio emission physics and present the experimental evidence supporting it. Finally, we discuss the potential for future applications of the radio detection technique to advance the field of cosmic ray physics. © 2016 Elsevier B.V.

Kotetes P.,Karlsruhe Institute of Technology
New Journal of Physics | Year: 2013

I perform a complete classification of two-dimensional, quasi-one-dimensional (1D) and 1D topological superconductors which originate from the suitable combination of inhomogeneous Rashba spin-orbit coupling, magnetism and superconductivity. My analysis reveals alternative types of topological superconducting platforms for which Majorana fermions are accessible. Specifically, I observe that for quasi-1D systems with Rashba spin-orbit coupling and time-reversal violating superconductivity, such as for instance due to a finite Josephson current flow, Majorana fermions can emerge even in the absence of magnetism. Furthermore, for the classification I also consider situations where additional 'hidden' symmetries emerge, with a significant impact on the topological properties of the system. The latter generally originate from a combination of space group and complex conjugation operations that separately do not leave the Hamiltonian invariant. Finally, I suggest alternative directions in topological quantum computing for systems with additional unitary symmetries. © IOP Publishing and Deutsche Physikalische Gesellschaft.

Lopez-Val D.,University of Heidelberg | Plehn T.,University of Heidelberg | Rauch M.,Karlsruhe Institute of Technology
Journal of High Energy Physics | Year: 2013

Extended Higgs sectors appear in many models for physics beyond the Standard Model. Current Higgs measurements at the LHC are starting to significantly constrain them. We study their Higgs coupling patterns at tree level as well as including quantum corrections. Our benchmarks include a dark singlet-doublet extension and several twodoublet setups. Using SFitter we translate the current Higgs coupling measurements for one light Higgs state into their respective parameter spaces. Finally, we show how two- Higgs-doublet models can serve as a consistent ultraviolet completion of an assumed single Standard-Model-like Higgs boson with free couplings. © SISSA 2013.

Hertz H.G.,Karlsruhe Institute of Technology
Pure and Applied Chemistry | Year: 2013

Solvation of ions as a microscopic property is understood to be given by certain time independent and time dependent probability functions which describe the structure and internal dynamics around the ions in a heap of mass points representing ions and solvent species in the liquid state. It is shown in an abbreviated and simple form in which way the three macroscopic observables ω, T1, T2 characterizing one of the nuclear magnetizations of the solution give a partial and truncated picture of the microscopic object of interest here. Interpretation of chemical shift data very often is rendered more difficult by the fact that the local microscopic magnetic field is determined by the electron density, for the nuclear magnetic relaxation data this is the case to a much lesser degree. Literature references referring to nonaqueous solutions are given as examples for the basic relations outlined where for reasons of room detailed discussion is not possible. © 2013, Walter de Gruyter. All rights reserved.

Hassler U.,ETH Zurich | Kohler N.,Karlsruhe Institute of Technology
Building Research and Information | Year: 2014

Uta Hassler and Niklaus Kohler informed that the modern engineering concept of resilience originated from material technology in the 19th century. This modern approach replaced the traditional dimensioning rules by formal rules of calculation to optimize structural safety and the reduced consumption of materials. Development of the resilience concept involved a move from an approach to maintain stability to one that explicitly acknowledged a dynamic system that changed over time. This dynamic system constituted a contemporary blueprint involving multiple equilibria and an adaptive change concept. A number of different disciplines adopted the term 'resilience' and applied it to ecological, psychological, social, socio-technical, organizational, and social-ecological systems over a long period of time. A growing number of domain-related resilience concepts continued to exist with their specific definitions.

Paradies J.,Karlsruhe Institute of Technology
Angewandte Chemie - International Edition | Year: 2014

The metal-free activation of hydrogen by frustrated Lewis pairs (FLPs) is a valuable method for the hydrogenation of polarized unsaturated molecules ranging from imines, enamines, and silyl enol ethers to heterocycles. However, one of the most important applications of hydrogenation technology is the conversion of unsaturated hydrocarbons into alkanes or alkenes. Despite the fast development of the FLP chemistry, such reactions proved as highly challenging. This Minireview provides an overview of the basic concepts of FLP chemistry, the challenge in the hydrogenation of unsaturated hydrocarbons, and first solutions to this central transformation. Recent metal-free approaches to the hydrogenation of nonpolar double and triple bonds using molecular hydrogen are described. Despite transition-metal-based methodologies for these fundamental chemical transformations, metal-free alternatives are highly desirable. Such technology has only been recently introduced with the aid of frustrated Lewis pairs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sahlmann H.,Karlsruhe Institute of Technology
Classical and Quantum Gravity | Year: 2010

In a remarkable paper (Koslowski T A 2007 arXiv:0709.3465[gr-qc]), Koslowski introduced kinematical representations for loop quantum gravity in which a non-degenerate spatial background metric is present. He also considered their properties and showed that Gauß and diffeomorphism constraints can be implemented. With this paper, we streamline and extend his treatment. In particular, we show that the standard regularization of the geometric operators leads to well-defined operators in the new representations, and we work out their properties fully. We also give details on the implementation of the constraints. All of this is done in such a way as to show that the standard representation is a particular (and in some ways exceptional) case of the more general constructions. This does not mean that these new representations are as fundamental as the standard one. Rather, we believe they might be useful to find some form of effective theory of loop quantum gravity on large scales. © 2010 IOP Publishing Ltd.

Keilhauer B.,Karlsruhe Institute of Technology
Astrophysics and Space Sciences Transactions | Year: 2010

The southern part of the Pierre Auger Observatory in Argentina investigates cosmic rays with energies above about 5·1017 eV. High-energy events which have been recorded with both detector components, surface water Cherenkov tanks and fluorescence telescopes, are crucial for the energy calibration of the entire detector system. Using this method, the energy reconstruction of extensive air showers relies on a proper fluorescence light reconstruction which depends on the knowledge of atmospheric conditions like pressure, temperature and water vapour. These properties of the atmosphere vary with altitude and in time. Therefore, a dedicated monitoring programme has operated since March 2009 to measure an actual atmospheric profile with meteorological radio soundings shortly after the detection of a high-energy air shower with E0 > 2·1019 eV. We will present the technical implementation of this programme as well as a reconstruction analysis using the data obtained. The reconstructed primary energy of air showers and the position of the shower maximum are compared with those results using either monthly models for the local atmospheric conditions or global meteorological models. © Author(s) 2010.

Dewald U.,Karlsruhe Institute of Technology | Fromhold-Eisebith M.,RWTH Aachen
Environmental Innovation and Societal Transitions | Year: 2015

This paper proposes that spatial dynamics of new environmental technologies can be better understood when positioned in a multi-scalar theoretical framework based on innovation system approaches. We combine territorial innovation system concepts with a technological innovation systems (TIS) perspective. The investigation of photovoltaic (PV) technology in Germany indicates that the relevance of different scales and actor constellations shifts in the course of a 'maturing' innovation system. First, the convergence of regional and institutional subsystems forms a temporary window of opportunity for a robust TIS formation within a national framing. Second, consolidation according to basic patterns of the underlying national innovation system takes place. This is illustrated by the robust performance of German mechanical PV equipment suppliers within a globalized PV value chain. The empirical findings allow for drafting a theoretical framework that offers a generalized view on this shifting spatial context pattern of an emerging environmental technology. © 2015 Elsevier B.V. All rights reserved.

Hart-Smith G.,University of New South Wales | Barner-Kowollik C.,Karlsruhe Institute of Technology
Macromolecular Chemistry and Physics | Year: 2010

For many decades, the capacity for mass spectrometry (MS) to analyse matterin all of its forms was shackled by an inability to ionise large molecules into the gas phase. It was only in the late 1980s, when the capabilities of the 'soft' ionisation protocols of matrix-assisted laser desorption/ ionisation (MALDI) and electrospray ionisation (ESI) became apparent, that these shackles were effectively removed. The emergence of soft ionisation methodologies acted as a driving force for significant advances in MS instrumentation; as a result, MS now represents one of the most potent means by which insights into the structural details of synthetic polymer samples can be obtained.However, despiteMSbeing acknowledged to be a mainstream analytical tool in the field of polymer chemistry, the number of MS-based studies into polymer systems remains significantly limited whencompared to other analytical methods, and it would thus appear that MS is still being severely underutilised. In this Trend article, important fundamental concepts of soft ionisation MS are presented in a tutorial style fashion within the context of the analysis of polymer systems, and the remarkable breadth, power andversatility of these techniques is illustrated using selected examples. We suggest that MS-based analyses represent one of the most promising areas of research in polymer science, and that the polymer chemistry community would bewell servedby utilising this analytical discipline in a more intensive manner. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Karlewski C.,Karlsruhe Institute of Technology
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

We present an exact expansion of the master equation for an open quantum system. The resulting equation is time local and enables us to calculate clearly defined higher-order corrections to the Born-Markov approximation. In particular, we show that non-Markovian terms are of the same order of magnitude as higher-order terms in the system-bath coupling. As a result, we emphasize that analyzing non-Markovian behavior of a system implies going beyond the Born approximation. Additionally, we address with this approach the initial-state problem occurring in non-Markovian master equations. © 2014 American Physical Society.

Wegner L.H.,Karlsruhe Institute of Technology
Bioelectrochemistry | Year: 2015

Membrane permeabilization by pulsed electric fields (electroporation), that is supposed to be caused by the formation of aqueous pores, is widely used in biomedicine and biotechnology. It is detected most precisely by measuring membrane conductance. When whole-cell patch-clamp experiments are used to screen a wide voltage range, poration becomes manifest by large currents elicited at extreme hyper-/depolarization. The slope conductance, Gslope, can be obtained from non-linear current-voltage relations by differentiation of the current-voltage curve. Alternatively, the chord conductance, Gchord, is defined as the slope of straight lines connecting each point on the current-voltage curve with the zero-current (reversal) potential on the voltage axis. Here, Boltzmann functions were fitted to plots of Gchord versus voltage recorded on protoplasts from bright-yellow-2 tobacco cells. These plots are supposed to reflect transition from a non-porated to a porated membrane state. Consistently, Gchord saturated at extremely negative and positive voltages at values well below those expected for a complete demolition of the membrane (half-maximum voltages: ~-332mV and +294mV, respectively). The slope factor allowed inferring the change in dipole moment associated with water intrusion into the bilayer. It was -6.19 10-4 and 3.35 10-4C*m*mol-1, respectively. Outside-out patches rendered similar results, but half-maximum voltages were shifted to more extreme voltages with respect to whole-cell experiments. © 2014 Elsevier B.V.

Klimenkov M.,Karlsruhe Institute of Technology
Journal of Nuclear Materials | Year: 2011

Quantitative analysis of Ar gas in nano-sized bubbles in ODS steel was performed using spatially resolved energy-dispersive X-ray spectroscopy. The Ar Kα line was quantified and used for calculation of Ar the concentration (atoms per nm3) inside 4-38 nm large bubbles. The Ar concentration and pressure inside bubbles were found to depend on the bubble size. The results were compared with a known equilibrium pressure model developed for calculation of He pressure inside nano-sized bubbles. Several investigations were performed to determine the stability of Ar bubbles in the thin TEM foil. © 2011 Elsevier B.V. All rights reserved.

Sangwai J.S.,Indian Institute of Technology Madras | Oellrich L.,Karlsruhe Institute of Technology
Fluid Phase Equilibria | Year: 2014

Phase equilibria of semiclathrate hydrates are important for their successful engineering applications due to more favorable process conditions compared to classical gas hydrate systems. Though sufficient information on the phase equilibria of semiclathrate hydrates of methane (CH4) in tetra-n-butyl ammonium bromide (TBAB) seems to be available, there are pronounced disagreements on the phase equilibrium data, particularly for 0.05 and 0.20 mass fraction (w) of TBAB. In this work, experimental studies are carried out to generate the equilibrium pressure (P) and temperature (T) for hydrates and semiclathrate hydrates of CH4 in an aqueous solution containing wTBAB=0.05 and 0.20 at P and T range of 1.02-13.73MPa and 281.63-294.54K, respectively. This study tries to clarify the discrepancy of published data in the literature and their reliability. Additionally, we present interesting insights into the phase behavior of semiclathrate hydrate of methane in TBAB based on the formation and dissociation curves observed in the experiments. It is observed that there existed two equilibrium points during the dissociation of semiclathrate hydrates of methane in TBAB; one closely corresponds to the pure methane hydrate phase stability curve and the second one to the semiclathrate hydrate system of methane. In addition phase equilibrium data is generated for the quaternary system of CH4+TBAB+H2O+NaCl for wNaCl=0.03 and 0.10 and wTBAB=0.05 and 0.20 in an aqueous solution at a P and T range of 1.65-20.71MPa and 281.19-296.38K, respectively. This is not yet available in the open literature. It is observed that NaCl inhibits the semiclathrate hydrate formation of CH4 in TBAB for wNaCl=0.03 and 0.10 in wTBAB=0.20 in the system. However, a promotion effect is observed for wNaCl=0.03 in wTBAB=0.05. This study calls for more detailed investigations on the effect of salts on semiclathrate hydrate systems, which may find potential use in engineering applications. © 2014 Elsevier B.V.

Rauner A.,University of Konstanz | Mess F.,University of Konstanz | Woll A.,Karlsruhe Institute of Technology
BMC Pediatrics | Year: 2013

Background: Not only in adults but also in children and adolescents, obesity increases the risk for several health disorders. In turn, many factors including genetic variations and environmental influences (e.g. physical activity) increase the risk of obesity. For instance, 25 to 40 percent of people inherit a predisposition for a high body mass index (BMI). The purpose of this systematic review was to summarize current cross-sectional and longitudinal studies on physical activity, fitness and overweight in adolescents and to identify mediator and moderator effects by evaluating the interaction between these three parameters.Methods: The electronic academic databases PubMed, SportDiscus, WEB OF KNOWLEDGE and Ovid were searched for studies on physical activity, fitness and overweight in adolescents aged 11 to 19 years (cross-sectional studies) and in adolescents up to 23 years old (longitudinal studies) published in English in or after 2000.Results: Twelve cross-sectional and two longitudinal studies were included. Only four studies analyzed the interaction among physical activity, fitness and overweight in adolescents and reported inconsistent results. All other studies analyzed the relationship between either physical activity and overweight, or between fitness and overweight. Overweight-here including obesity-was inversely related to physical activity. Similarly, all studies reported inverse relations between physical fitness and overweight. Mediator and moderator effects were detected in the interrelationship of BMI, fitness and physical activity. Overall, a distinction of excessive body weight as cause or effect of low levels of physical activity and fitness is lacking.Conclusions: The small number of studies on the interrelationship of BMI, fitness and physical activity emphasizes the need for longitudinal studies that would reveal 1) the causality between physical activity and overweight / fitness and overweight and 2) the causal interrelationships among overweight, physical activity and fitness. These results must be carefully interpreted given the lack of distinction between self-reported and objective physical activity and that studies analyzing the metabolic syndrome or cardiovascular disease were not considered. The importance of physical activity or fitness in predicting overweight remains unknown. © 2013 Rauner et al.; licensee BioMed Central Ltd.

Dierlamm A.,Karlsruhe Institute of Technology
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2010

It is foreseen to significantly increase the luminosity of the Large Hadron Collider (LHC) at CERN around 2018 by upgrading the LHC towards the SLHC (Super-LHC). Due to the radiation damage to the silicon detectors used, the physics experiments will require new tracking detectors for SLHC operation. All-silicon central trackers are being studied in ATLAS, CMS and LHCb, with extremely radiation hard silicon sensors for the innermost layers. The radiation hardness of these new sensors must surpass the one of LHC detectors by roughly one order of magnitude. Within the CERN RD50 collaboration, a massive R&D program is underway to develop silicon sensors with sufficient radiation tolerance. We will report on recent results obtained by RD50 from tests of several detector technologies and silicon materials at radiation levels corresponding to SLHC fluences. Based on these results, we will give recommendations for the silicon detector technologies to be used at the different radii of SLHC tracking systems. © 2010 Elsevier B.V. All rights reserved.

Ismail A.,Damanhour University | Takeda S.,Nagoya University | Nick P.,Karlsruhe Institute of Technology
Journal of Experimental Botany | Year: 2014

Salinity does not only stress plants but also challenges human life and the economy by posing severe constraints upon agriculture. To understand salt adaptation strategies of plants, it is central to extend agricultural production to salt-affected soils. Despite high impact and intensive research, it has been difficult to dissect the plant responses to salt stress and to define the decisive key factors for the outcome of salinity signalling. To connect the rapidly accumulating data from different systems, treatments, and organization levels (whole-plant, cellular, and molecular), and to identify the appropriate correlations among them, a clear conceptual framework is required. Similar to other stress responses, the molecular nature of the signals evoked after the onset of salt stress seems to be general, as with that observed in response to many other stimuli, and should not be considered to confer specificity per se. The focus of the current review is therefore on the temporal patterns of signals conveyed by molecules such as Ca2+, H+, reactive oxygen species, abscisic acid, and jasmonate. We propose that the outcome of the salinity response (adaptation versus cell death) depends on the timing with which these signals appear and disappear. In this context, the oftenneglected non-selective cation channels are relevant. We also propose that constraining a given signal is as important as its induction, as it is the temporal competence of signalling (signal on demand) that confers specificity. © The Author 2014.

Maierhofer P.,University of Zurich | Marquard P.,Karlsruhe Institute of Technology
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We present the result for the three-loop singlet QCD corrections to the decay of a Higgs boson into two photons and improve the calculation for the non-singlet case. With the new result presented, the decay width Γ(H → γγ) is completely known at O(GFα2αs 2,GFα3). © 2013 Elsevier B.V.

Stadler A.-M.,CNRS Institute of Science and Supramolecular Engineering | Stadler A.-M.,Karlsruhe Institute of Technology | Lehn J.-M.P.,CNRS Institute of Science and Supramolecular Engineering
Journal of the American Chemical Society | Year: 2014

A new class of shape-enforced synthetic polyheterocyclic molecular strands, containing both a helical and a linear domain, has been designed and synthesized. On reaction with Pb(II), under the effect of cation binding to the coordination subunits, the helical section unfolds into a linear shape in the complex and the linear domain folds into a helical ligand wrapped around the bound cations. Such double-domain ligand strands are thus able to undergo a combined unfolding-folding interconversion on binding and release of metal cations. These changes can be modulated through coupling to a competing ligand that reversibly binds and releases metal cations, when respectively unprotonated and protonated, on effecting alternate pH changes. The resulting process thus performs nanomechanical extension/contraction molecular motions of a linear motor type, which is fueled by acid-base neutralization. © 2014 American Chemical Society.

Jacob C.R.,Karlsruhe Institute of Technology
Journal of Chemical Physics | Year: 2011

The optimization of effective potentials is of interest in density-functional theory (DFT) in two closely related contexts. First, the evaluation of the functional derivative of orbital-dependent exchange-correlation functionals requires the application of optimized effective potential methods. Second, the optimization of the effective local potential that yields a given electron density is important both for the development of improved approximate functionals and for the practical application of embedding schemes based on DFT. However, in all cases this optimization turns into an ill-posed problem if a finite basis set is introduced for the Kohn-Sham orbitals. So far, this problem has not been solved satisfactorily. Here, a new approach to overcome the ill-posed nature of such finite-basis set methods is presented for the optimization of the effective local potential that yields a given electron density. This new scheme can be applied with orbital basis sets of reasonable size and makes it possible to vary the basis sets for the orbitals and for the potential independently, while providing an unambiguous potential that systematically approaches the numerical reference. © 2011 American Institute of Physics.

Nusinovich G.S.,University of Maryland University College | Thumm M.K.A.,Karlsruhe Institute of Technology | Petelin M.I.,RAS Institute of Applied Physics
Journal of Infrared, Millimeter, and Terahertz Waves | Year: 2014

Gyrotrons form a specific group of devices in the class of fast-wave vacuum electronic sources of coherent electromagnetic wave radiation known as electron cyclotron masers (ECMs) or cyclotron resonance masers (CRMs). The operation of CRMs is based on the cyclotron maser instability which originates from the relativistic dependence of the electron cyclotron frequency on the electron energy. This relativistic effect can be pronounced even at low voltages when the electron kinetic energy is small in comparison with the rest energy. The free energy for generation of electromagnetic (EM) waves is the energy of electron gyration in an external magnetic field. As in any fast-wave device, the EM field in a gyrotron interaction space is not localized near a circuit wall (like in slow-wave devices), but can occupy large volumes. Due to possibilities of using various methods of mode selection (electrodynamical and electronic ones), gyrotrons can operate in very high order modes. Since the use of large, oversized cavities and waveguides reduces the role of ohmic wall losses and breakdown limitations, gyrotrons are capable of producing very high power radiation at millimeter and submillimeter wavelengths. The present review is restricted primarily by the description of the development and the present state-of-the-art of gyrotrons for controlled thermonuclear fusion plasma applications. The first gyrotron was invented, designed and tested in Gorky, USSR (now Nizhny Novgorod, Russia), in 1964. © 2014 Springer Science+Business Media New York.

Koos E.,Karlsruhe Institute of Technology
Current Opinion in Colloid and Interface Science | Year: 2014

The addition of small amounts of a secondary fluid to a suspension can, through the attractive capillary force, lead to particle bridging and network formation. The capillary bridging phenomenon can be used to stabilize particle suspensions and precisely tune their rheological properties. This effect can even occur when the secondary fluid wets the particles less well than the bulk fluid. These materials, so-called capillary suspensions, have been the subject of recent research studying the mechanism for network formation, the properties of these suspensions, and how the material properties can be modified. Recent work in colloidal clusters is summarized and the relationship to capillary suspensions is discussed. Capillary suspensions can also be used as a pathway for new material design and some of these applications are highlighted. Results obtained to date are summarized and central questions that remain to be answered are proposed in this review. © 2014 Elsevier Ltd.

Gaus M.,University of Wisconsin - Madison | Cui Q.,University of Wisconsin - Madison | Elstner M.,Karlsruhe Institute of Technology
Wiley Interdisciplinary Reviews: Computational Molecular Science | Year: 2014

In this work, we review recent extensions of the density functional tight binding (DFTB) methodology and its application to organic and biological molecules. DFTB denotes a class of computational models derived from density functional theory (DFT) using a Taylor expansion around a reference density. The first- and second-order models, DFTB1 and DFTB2, have been reviewed recently (WIREs Comput Mol Sci 2012, 2:456-465). Here, we discuss the extension to third order, DFTB3, which in combination with a modification of the Coulomb interactions in the second-order formalism and a new parametrization scheme leads to a significant improvement of the overall performance. The performance of DFTB2 and DFTB3 for organic and biological molecules are discussed in detail, as well as problems and limitations of the underlying approximations. © 2013 John Wiley & Sons, Ltd.

Jacob C.R.,Karlsruhe Institute of Technology | Neugebauer J.,University of Munster
Wiley Interdisciplinary Reviews: Computational Molecular Science | Year: 2014

Subsystem density-functional theory (subsystem DFT) has developed into a powerful alternative to Kohn-Sham DFT for quantum chemical calculations of complex systems. It exploits the idea of representing the total electron density as a sum of subsystem densities. The optimum total density is found by minimizing the total energy with respect to each of the subsystem densities, which breaks down the electronic-structure problem into effective subsystem problems. This enables calculations on large molecular aggregates and even (bio-)polymers without system-specific parameterizations. We provide a concise review of the underlying theory, typical approximations, and embedding approaches related to subsystem DFT such as frozen-density embedding (FDE). Moreover, we discuss extensions and applications of subsystem DFT and FDE to molecular property calculations, excited states, and wave function in DFT embedding methods. Furthermore, we outline recent developments for reconstruction techniques of embedding potentials arising in subsystem DFT, and for using subsystem DFT to incorporate constraints into DFT calculations. © 2013 John Wiley & Sons, Ltd.

Emeis S.,Karlsruhe Institute of Technology
Meteorological Applications | Year: 2014

This review discusses some of the current issues in wind energy meteorology from the viewpoint of a meteorologist. The focus is on four major subjects: (1) the wind potential, (2) the influence of major terrain inhomogeneities on this wind potential, (3) diurnal wind variations and (4) the impact of wind turbines and wind parks on the flow. The wind potential is addressed by describing vertical profiles of wind and turbulence, trying to give profile laws that are valid throughout the major part of the atmospheric boundary layer and specifying specific offshore turbulence conditions. Flow over forests and gently sloping hills are presented as two examples for the very broad spectrum of possible terrain inhomogeneities. Diurnal variations of wind speed turn out to be height dependent. A major diurnal variation, the formation of low-level jets, is discussed in detail. Finally, wakes of single turbines and of entire wind parks are addressed and an analytical model for park efficiency and wake is presented. This review gives only a short overview on the spectrum of issues in wind energy meteorology. A few analytical approaches are presented to explain first-order effects. Detailed investigations of wind and turbulence conditions usually require the use of non-linear high-resolution flow models. © 2014 Royal Meteorological Society.

Salichos L.,Vanderbilt University | Stamatakis A.,Exelixis | Stamatakis A.,Karlsruhe Institute of Technology | Rokas A.,Vanderbilt University
Molecular Biology and Evolution | Year: 2014

Phylogenies inferred from different data matrices often conflict with each other necessitating the development of measures that quantify this incongruence. Here, we introduce novel measures that use information theory to quantify the degree of conflict or incongruence among all nontrivial bipartitions present in a set of trees. The first measure, internode certainty (IC), calculates the degree of certainty for a given internode by considering the frequency of the bipartition defined by the internode (internal branch) in a given set of trees jointly with that of the most prevalent conflicting bipartition in the same tree set. The secondmeasure, IC All (ICA), calculates the degree of certainty for a given internode by considering the frequency of the bipartition defined by the internode in a given set of trees in conjunction with that of all conflicting bipartitions in the same underlying tree set. Finally, the tree certainty (TC) and TC All (TCA) measures are the sum of IC and ICA values across all internodes of a phylogeny, respectively. IC, ICA, TC, and TCA can be calculated from different types of data that contain nontrivial bipartitions, including from bootstrap replicate trees to gene trees or individual characters. Given a set of phylogenetic trees, the IC and ICA values of a given internode reflect its specific degree of incongruence, and the TC and TCA values describe the global degree of incongruence between trees in the set. All four measures are implemented and freely available in version 8.0.0 and subsequent versions of the widely used program RAxML. © The Author 2014.

Kawahara G.,Osaka University | Uhlmann M.,Karlsruhe Institute of Technology | Van Veen L.,University of Ontario Institute of Technology
Annual Review of Fluid Mechanics | Year: 2011

Recent remarkable progress in computing power and numerical analysis is enabling us to fill a gap in the dynamical systems approach to turbulence. A significant advance in this respect has been the numerical discovery of simple invariant sets, such as nonlinear equilibria and periodic solutions, in well-resolved Navier-Stokes flows. This review describes some fundamental and practical aspects of dynamical systems theory for the investigation of turbulence, focusing on recently found invariant solutions and their significance for the dynamical and statistical characterization of low-Reynolds-number turbulent flows. It is shown that the near-wall regeneration cycle of coherent structures can be reproduced by such solutions. The typical similarity laws of turbulence, i.e., the Prandtl wall law and the Kolmogorov law for the viscous range, as well as the pattern and intensity of turbulence-driven secondary flow in a square duct can also be represented by these simple invariant solutions.

Pacas M.,Karlsruhe Institute of Technology
IEEE Industrial Electronics Magazine | Year: 2011

Worldwide intensive research in the field of advanced control schemes for ac drives has been performed during the last few years. Parallel efforts in industry and academia aimed the development of sensorless ac drives featuring a dynamic behavior comparable or similar to the drives with mechanical sensor on the shaft. Some of these works and ideas can be found in industrial products and systems available on the market. This article discusses the state of the art of sensorless drives in industrial applications and the reasons that determine the acceptance or refusal of the different solutions on the side of manufacturers of motor drives. © IEEE.

Ruehle C.,Karlsruhe Institute of Technology
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2012

Radio detection provides information about the electromagnetic part of an air shower in the atmosphere complementary to that obtained by water-Cherenkov detectors predominantly sensitive to the muonic content of an air shower at ground. For the measurement of ultra-high-energy cosmic rays (UHECR) by the detection of their coherent radio emission, several test setups have been developed and deployed at the Pierre Auger Observatory in Argentina. However, these UHECR radio pulses are significantly polluted by man-made radio frequency interferences (RFI). This requires a special design of antennas, analog, data acquisition (DAQ), and communication electronics, which are under investigation at the Pierre Auger Observatory. In large-scale detector arrays sophisticated self-triggering methods are necessary, to use the limited available communication data rate efficiently. This paper gives an overview of the electronics and self-triggering methods used in the test setups at the Pierre Auger Observatory and describes the experiences gained so far. © 2010 Elsevier B.V.

Schulz H.,Karlsruhe Institute of Technology
Catalysis Today | Year: 2010

Deactivation of acidic zeolite catalysts during methanol conversion is investigated for elucidating how spatial constraints interfere mechanistically. Detailed product composition - including retained organic matter - is determined in a time resolved mode. At 270-300 °C with H-ZSM-5, first unsaturated hydrocarbons are formed - methane being the indicative co-product. Then the reaction rate increases auto-catalytically, but soon declines because of exhaustive pore filling. The retained organic matter consists mainly of ethyl-trimethyl-benzene- and isopropyl-dimethyl-benzene molecules. Alkylation of benzene rings with ethene and propene produces the deactivating molecules. At 475 °C, alkylation of benzene rings with olefins has shifted to the reverse, reactivating the H-ZSM-5 catalyst. Coke forms slowly on the surface of H-ZSM-5 crystallites. Spatial constraints suppress the formation of 2-ring aromatics. With the wide pore zeolite H-Y, fast deactivation is noticed - bigger aromatic molecules can be formed and are retained. Methanol reactions on the protonic catalyst sites are visualized as CH 3+ attack for methylation and dehydrogenation, methane being the hydrogen-rich co-product. Methanol conversion on zeolites H-ZSM-58, H-EU-1 and H-Beta is comparatively investigated. Zone ageing is discussed for favorable reactor design. It is shown, how a multi-compound product composition is the source of information for elucidating complex reaction mechanisms. © 2010 Elsevier B.V. All rights reserved.

Ashworth K.,Lancaster University | Ashworth K.,Karlsruhe Institute of Technology | Wild O.,Lancaster University | Hewitt C.N.,Lancaster University
Nature Climate Change | Year: 2013

Ground-level ozone is a priority air pollutant, causing ∼ 22,000 excess deaths per year in Europe, significant reductions in crop yields and loss of biodiversity. It is produced in the troposphere through photochemical reactions involving oxides of nitrogen (NO x) and volatile organic compounds (VOCs). The biosphere is the main source of VOCs, with an estimated 1,150 TgC yr -1 (∼ 90% of total VOC emissions) released from vegetation globally. Isoprene (2-methyl-1,3-butadiene) is the most significant biogenic VOC in terms of mass (around 500 TgC yr -1) and chemical reactivity and plays an important role in the mediation of ground-level ozone concentrations. Concerns about climate change and energy security are driving an aggressive expansion of bioenergy crop production and many of these plant species emit more isoprene than the traditional crops they are replacing. Here we quantify the increases in isoprene emission rates caused by cultivation of 72 Mha of biofuel crops in Europe. We then estimate the resultant changes in ground-level ozone concentrations and the impacts on human mortality and crop yields that these could cause. Our study highlights the need to consider more than simple carbon budgets when considering the cultivation of biofuel feedstock crops for greenhouse-gas mitigation. © 2013 Macmillan Publishers Limited. All rights reserved.

Nick P.,Karlsruhe Institute of Technology
Protoplasma | Year: 2012

Plant microtubules have evolved into a versatile tool to link environmental signals into flexible morphogenesis. Cortical microtubules define the axiality of cell expansion by control of cellulose orientation. Plant-specific microtubule structures such as preprophase band and phragmoplast determine symmetry and axiality of cell divisions. In addition, microtubules act as sensors and integrators for stimuli such as mechanic load, gravity, but also osmotic stress, cold and pathogen attack. Many of these functions are specific for plants and involve specific proteins or the recruitment of proteins to new functions. The review aims to ventilate the potential of microtubule-based strategies for biotechnological application by highlighting representative case studies. These include reorientation of cortical microtubules to increase lodging resistance, control of microtubule dynamics to alter the gravity-dependent orientation of leaves, the use of microtubules as sensitive thermometers to improve adaptive cold tolerance of chilling and freezing sensitive plants, the reduction of microtubule treadmilling to inhibit cell-to-cell transport of plant viruses, or the modulation of plant defence genes by pharmacological manipulation of microtubules. The specificity of these responses is controlled by a great variety of specific associated proteins opening a wide field for biotechnological manipulation of plant architecture and stress tolerance. © 2011 Springer-Verlag.

Tentyukov M.,Karlsruhe Institute of Technology | Vermaseren J.A.M.,Nikhef Theory Group
Computer Physics Communications | Year: 2010

We present TFORM, the version of the symbolic manipulation system FORM that can make simultaneous use of several processors in a shared memory architecture. The implementation uses Posix threads, also called pthreads, and is therefore easily portable between various operating systems. Most existing FORM programs will be able to take advantage of the increased processing power, without the need for modifications. In some cases some minor additions may be needed. For a computer with two processors a typical improvement factor in the running time is 1.7 when compared to the traditional version of FORM. In the case of computers with 4 processors a typical improvement factor in the execution time is slightly above 3. © 2010 Elsevier B.V. All rights reserved.

Bauer C.,German Aerospace Center | Zitterbart M.,Karlsruhe Institute of Technology
IEEE Communications Surveys and Tutorials | Year: 2011

The aviation industry is currently at the beginning of a modernization phase regarding its communication systems. This involves a transition to IP-based networks for Air Traffic Control and Airline Operational Communications. Due to the heterogeneous nature of the communication environment, support for mobility between different access technologies and access networks becomes necessary. We first introduce the aeronautical communications environment and present domain specific requirements. The main part of this article is a survey of different protocols that can be used to solve the IP mobility problem within the aeronautical environment. These protocols are assessed with regard to the introduced requirements. We conclude with the identification of a particular protocol as the most suited solution and also identify areas for further work. © 2011 IEEE.

Breunig M.,Karlsruhe Institute of Technology | Zlatanova S.,Technical University of Delft
Computers and Geosciences | Year: 2011

3D geo-database research is a promising field to support challenging applications such as 3D urban planning, environmental monitoring, infrastructure management, and early warning or disaster management and response. In these fields, interdisciplinary research in GIScience and related fields is needed to support the modelling, analysis, management, and integration of large geo-referenced data sets, which describe human activities and geophysical phenomena. Geo-databases may serve as platforms to integrate 2D maps, 3D geo-scientific models, and other geo-referenced data. However, current geo-databases do not provide sufficient 3D data modelling and data handling techniques. New 3D geo-databases are needed to handle surface and volume models. This article first presents a 25-year retrospective of geo-database research. Data modelling, standards, and indexing of geo-data are discussed in detail. New directions for the development of 3D geo-databases to open new fields for interdisciplinary research are addressed. Two scenarios in the fields of early warning and emergency response demonstrate the combined management of human and geophysical phenomena. The article concludes with a critical outlook on open research problems. © 2011 Elsevier Ltd.

Dittmeyer R.,Karlsruhe Institute of Technology | Bortolotto L.,Dechema Institute
Applied Catalysis A: General | Year: 2011

The surface of hydrogen-permeable PdCu membranes acting as a catalyst for direct hydroxylation of benzene to phenol in the gas phase in a novel catalytic double-membrane reactor was modified by sputtering on it different catalytic layers with the aim to increase the formation rate and selectivity to phenol. Three different systems are described: a 1 μm thick compact layer of Pd 90Au10 (10 wt.% Au), a 5 μm thick compact layer of PdGa (50 at.% Ga) and a thin film of Pd90Au10 deposited on a discontinuous V2O5 layer. The different systems were characterized by SEM, EDX, and mainly in terms of their catalytic properties for benzene hydroxylation. The formation rate and the selectivity to phenol could be increased substantially through the catalytic modification. With a maximum phenol selectivity of 67% at 150 °C and a maximum phenol formation rate of 1.67 × 10-4 mol h-1 m-2 at 200 °C, PdAu reached the best performance in double-membrane operation mode. PdGa showed even more promising results compared to PdAu in kinetic experiments in co-feed operation mode, but suffers from the very low hydrogen permeability of PdGa which stands against its use as a continuous layer in the catalytic membrane reactor. © 2010 Elsevier B.V. All rights reserved.

Butterbach-Bahl K.,Karlsruhe Institute of Technology | Dannenmann M.,Albert Ludwigs University of Freiburg
Current Opinion in Environmental Sustainability | Year: 2011

Human activities have accelerated global nitrogen cycling by approx. a factor of two. Also under future environmental conditions, agricultural nitrogen use is expected to remain the leading cause of reactive nitrogen (Nr) release to the environment. The main process to remove Nr from the environment is microbial denitrification. Here we summarize potential mechanisms that may affect denitrification and associated nitrous oxide (N2O) emissions in/from agricultural systems under future environmental conditions. Though changes in climate, specifically in temperature and precipitation, are likely to directly affect denitrification rates and N2O emissions, we identified several indirect mechanisms of global change that may potentially override direct effects. Among these are a) landscape scale changes of hotspots of denitrification: while the importance of non-hydromorphic upland soils for denitrification may decrease owing to limitations in soil moisture the importance of riparian areas as denitrification hotspots may further increase owing to the increased likeliness of flooding events leading to more frequent occurrences of aerobic-anaerobic cycles in riparian areas and, thus, increased denitrification, b) increased provision of labile carbon substrates via plant root exudation in the rhizosphere under elevated atmospheric carbon dioxide (CO2) concentrations, leading to increased microbial activity and higher denitrification rates in agricultural subsoils, thereby potentially reducing rates of nitrate leaching from agricultural soils and c) increased ammonia (NH3) volatilization from agricultural systems leading to increased denitrification rates and N2O emissions downwind from NH3 emission sources. Obviously, under future environmental conditions the mentioned mechanisms would further strengthen the regional disjunction of areas of Nr application from those of Nr removal by denitrification, thereby calling for a reappraisal of the importance of indirect emissions of N2O from agricultural Nr use. It remains unclear, to which extent climate change mitigation options such as the introduction of no-till systems or the increasing use of slow release fertilizers in conjunction with nitrification inhibitors or the adaptations of agricultural management practices to climate change such as altered timing of cultivation, choice of crop varieties and adaptation of water saving production systems may finally override direct and indirect climate change effects on denitrification and N2O emissions from agricultural systems. © 2011 Elsevier B.V.

Biermann U.,Carl von Ossietzky University | Bornscheuer U.,University of Greifswald | Meier M.A.R.,Karlsruhe Institute of Technology | Metzger J.O.,Carl von Ossietzky University | Schafer H.J.,University of Munster
Angewandte Chemie - International Edition | Year: 2011

Oils and fats of vegetable and animal origin have been the most important renewable feedstock of the chemical industry in the past and in the present. A tremendous geographical and feedstock shift of oleochemical production has taken place from North America and Europe to southeast Asia and from tallow to palm oil. It will be important to introduce and to cultivate more and new oil plants containing fatty acids with interesting and desired properties for chemical utilization while simultaneously increasing the agricultural biodiversity. The problem of the industrial utilization of food plant oils has become more urgent with the development of the global biodiesel production. The remarkable advances made during the last decade in organic synthesis, catalysis, and biotechnology using plant oils and the basic oleochemicals derived from them will be reported, including, for example, w-functionalization of fatty acids containing internal double bonds, application of the olefin metathesis reaction, and de novo synthesis of fatty acids from abundantly available renewable carbon sources. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Emeis S.,Karlsruhe Institute of Technology
Wind Energy | Year: 2010

The analytical top-down wind park model by Emeis and Frandsen1 is enhanced by consistently making both the downward momentum flux and the momentum loss at the rough surface dependent on atmospheric stability. Specifying the surface roughness underneath the turbines in a wind farm in the model gives the opportunity to investigate principal differences between onshore and offshore wind parks, because the roughness length of the sea surface is two to three orders of magnitude lower than the roughness length of land surfaces. Implications for the necessary distance between single turbines in offshore wind farms and the distance between neighbouring wind parks are computed. It turns out from the model simulations that over smooth surfaces offshore the wind speed reduction at hub height in a wind farm is larger than over rough onshore surfaces given the same density of turbines within the park. Mean wind profiles within the park are also calculated from this model. Offshore wind farms must have a larger distance between each other in order to avoid shadowing effects of the upstream farm. © 2009 John Wiley & Sons, Ltd..

Wanner A.,Karlsruhe Institute of Technology
Materials and Design | Year: 2010

A systematic materials selection procedure for spatially limited, light-weight structural components is derived. The basic strategy is to utilize the available space to its full extent and introduce a free variable that accounts for the shape variation in the interior of the component necessary to meet the requirements as the material is varied. This approach leads to a specific class of objective equations and performance indices. By introducing constraint indices describing the combined demands from spatial limitations and functional requirements the performance indices attain relatively simple mathematical forms, thus facilitating the identification and ranking of viable shape-material combinations. © 2010 Elsevier Ltd. All rights reserved.

Korsch M.,Dental Academy for Continuing Professional Development | Obst U.,Karlsruhe Institute of Technology | Walther W.,Dental Academy for Continuing Professional Development
Clinical Oral Implants Research | Year: 2014

Background: Cement-retained fixed implant-supported restorations involve the risk of excess cement, which can associate peri-implantitis. In connection with routine therapy using a methacrylate cement (Premier Implant Cement, Premier® Dental Products Company, Plymouth Meeting, PA, USA) to retain fixed implant-supported restorations, complications, that is, inflammations, were developed in some cases. After removing the suprastructure and the abutment, residual excessive cement was found. For this reason, all implant-supported restorations that had been fixed with this type of methacrylate cement were reevaluated and retreated. Methods: In a retrospective clinical observational study including 71 patients with 126 implants, the findings made during retreatment were documented. In all cases, the suprastructure and the abutment were removed. For recementation, Temp Bond (Kerr Sybron Dental Specialities, Washington, D.C., USA) was used. If an inflammation had developed, a follow-up appointment was scheduled 3-4 weeks later. Results: In 59.5% of the implants, cement residues were identified. Bleeding on probing was diagnosed at 80% of the implants with excess cement and suppuration at 21.3% of the implants. After removal of the excess cement and recementation with Temp Bond, a 76.9% reduction in bleeding on probing was found at follow-up. Suppuration was not found around any of the implants at follow-up. Conclusion: Excess cement left in the implant-mucosal interface caused bleeding on probing in most cases and suppuration in some. The removal of excess cement after cementation should be given high priority. In this retrospective observational study, an unusually high number of implants with excess cement after cementation was found with the methacrylate cement applied in the study. © 2013 John Wiley & Sons A/S.

Zoller M.F.,Karlsruhe Institute of Technology
Journal of High Energy Physics | Year: 2014

In [1] an operator product expansion (OPE) at zero temperature was performed for the correlators of two scalar operators (Formula Presented) and two QCD energy-momentum tensors Tμν. There we presented analytical two-loop results for the Wilson coefficient C1 in front of the gluon condensate operator O1. In this paper these results are extended to three-loop order.Abstract: The correlator of two gluonic operators plays an important role for example in transport properties of a Quark Gluon Plasma (QGP) or in sum rules for glueballs.The three-loop Wilson coefficient C0 in front of the unity operator O0 = [InlineMediaObject not available: see fulltext.]was already presented in [1] for the Tμν-correlator. For the O1-correlator the coefficient C0 is known to four loop order from [2]. For the correlator of two pseudoscalar operators Õ1 = εμνρσGμνGρσ both coefficients C0 and C1 were computed in [3] to three-loop order. At zero temperature C0 and C1 are the leading Wilson coefficients in massless QCD. © 2014, The Author(s).

Wegner L.H.,Karlsruhe Institute of Technology
Journal of Experimental Botany | Year: 2014

The thermodynamics of root pressure remains an enigma up to the present day. Water is transported radially into xylem vessels, under some conditions even when the xylem sap is more dilute than the ambient medium (soil solution). It is suggested here that water secretion across the plasma membrane of xylem parenchyma cells is driven by a co-transport of water and solutes as previously shown for mammalian epithelia (Zeuthen T. 2010. Water-transporting proteins. Journal of Membrane Biology 234, 57-73.). This process could drive volume flow 'energetically uphill', against the free energy gradient of water. According to the model, solutes released by xylem parenchyma cells are subsequently retrieved from the sap at the expense of metabolic energy to maintain the concentration gradient that drives the water secretion. Transporters of the CCC type known to mediate water secretion in mammalian cells have also been found in Arabidopsis and in rice. The mechanism proposed here for root pressure could also explain refilling of embolized vessels. Moreover, it could contribute to long-distance water transport in trees when the cohesion-tension mechanism of water ascent fails. This is discussed with respect to the old and the more recent literature on these subjects. © © The Author 2013. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

This article deals with self-excited vibrations, attractivity of stationary solutions, and the corresponding bifurcation behavior of two-dimensional differential inclusions of the type Mq″ + Dq′ + (K + μN)q ∈-R Sign(q'). For the smooth case R=0, the equilibrium may become unstable due to non-conservative positional forces stemming from the circulatory matrix N. This type of instability is usually referred to as flutter instability and the loss of stability is related to a Hopf bifurcation of the steady state, which occurs for a critical parameter μ= μcrit. For R≠0, the steady state is a set of equilibria, which turns out to be attractive for all values of the bifurcation parameter μ. Depending on μ, the basin of attraction of the equilibrium set can be infinite or finite. The transition from an infinite to a finite basin of attraction occurs at the stability threshold μcrit of the underlying smooth problem. For the finite basin of attraction, its size is proportional to the Coulomb friction and inverse-proportional to (μ- μcrit). By adding Coulomb damping the notion of steady state stability for the smooth problem is replaced by the question whether the basin of attraction of the steady state is infinite or finite. Simultaneously, the local Hopf-bifurcation is replaced by a global bifurcation. This implies that in the presence of Coulomb damping the occurrence of self-excited vibrations can only be investigated with regard to the perturbation level. © 2013 Springer Science+Business Media Dordrecht.

Chalons G.,Karlsruhe Institute of Technology | Domingo F.,German Electron Synchrotron
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

We extend the low-energy effective field theory relevant for b→s transitions up to operators of mass dimension seven and compute the associated anomalous-dimension matrix. We then compare our findings to the known results for dimension-six operators and derive a solution for the renormalization group equations involving operators of dimension seven. We finally apply our analysis to a particularly simple case where the Standard Model is extended by an electroweak-magnetic operator and consider limits on this scenario from the decays Bs→μ+μ- and B→Kνν̄. © 2014 American Physical Society.

Klute M.,Massachusetts Institute of Technology | Lafaye R.,University of Savoy | Plehn T.,University of Heidelberg | Rauch M.,Karlsruhe Institute of Technology | Zerwas D.,French National Center for Scientific Research
Physical Review Letters | Year: 2012

Following recent ATLAS and CMS publications we interpret the results of their Higgs searches in terms of standard model operators. For a Higgs boson mass of 125A Gev we determine several Higgs couplings from published 2011 data and extrapolate the results towards different scenarios of LHC running. Even though our analysis is limited by low statistics we already derive meaningful constraints on modified Higgs sectors. © 2012 American Physical Society.

Gross S.,CNR Institute of Molecular Science and Technologies | Bauer M.,Karlsruhe Institute of Technology
Advanced Functional Materials | Year: 2010

The potential and application of X-ray absorption spectroscopy (XAS) for structural investigations of organic-inorganic hybrid materials, with a special emphasis on systems consisting of inorganic building blocks (clusters) embedded into polymer backbones, is extensively reviewed. In the first part of the paper, the main features of organic-inorganic hybrid materials, their classification, the synthetic approaches for their preparation, and their applications are concisely presented, whereas the particular issues related to their characterization are discussed in more detail. In the second section of the paper, the principles and the theoretical background of the XAS method, including experimental design, data reduction, evaluation, analysis, and interpretation are described and discussed. Examples of potentialities of the method for the short-range structural investigation of inorganic nanostructures in hybrids are provided, and the state-of-the-art in the field of hybrid materials is reviewed. In the third part, six different case studies belonging to our past and present experience in this field are presented and discussed, with a particular focus on their XAS investigation. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Shekhah O.,Karlsruhe Institute of Technology
Materials | Year: 2010

A layer-by-layer method has been developed for the synthesis of metal-organic frameworks (MOFs) and their deposition on functionalized organic surfaces. The approach is based on the sequential immersion of functionalized organic surfaces into solutions of the building blocks of the MOF, i.e., the organic ligand and the inorganic unit. The synthesis and growth of different types of MOFs on substrates with different functionalization, like COOH, OH and pyridine terminated surfaces, were studied and characterized with different surface characterization techniques. A controlled and highly oriented growth of very homogenous films was obtained using this method. The layer-bylayer method offered also the possibility to study the kinetics of film formation in more detail using surface plasmon resonance and quartz crystal microbalance. In addition, this method demonstrates the potential to synthesize new classes of MOFs not accessible by conventional methods. Finally, the controlled growth of MOF thin films is important for many applications like chemical sensors, membranes and related electrodes. © 2010 by the authors.

Mondejar J.,Karlsruhe Institute of Technology | Melnikov K.,Johns Hopkins University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

It is known that the correlator of one axial and two vector currents, that receives leading contributions through one-loop fermion triangle diagrams, is not modified by QCD radiative corrections at two loops. It was suggested that this non-renormalization of the 〈. VVA〉 correlator persists in higher orders in perturbative QCD as well. To check this assertion, we compute the three-loop QCD corrections to the 〈. VVA〉 correlator using the technique of asymptotic expansions. We find that these corrections do not vanish and that they are proportional to the QCD β-function. © 2012 Elsevier B.V.

Tembe S.,Karlsruhe Institute of Technology | Lockner D.A.,U.S. Geological Survey | Wong T.-F.,State University of New York at Stony Brook
Journal of Geophysical Research: Solid Earth | Year: 2010

We investigated the frictional sliding behavior of simulated quartz-clay gouges under stress conditions relevant to seismogenic depths. Conventional triaxial compression tests were conducted at 40 MPa effective normal stress on saturated saw cut samples containing binary and ternary mixtures of quartz, montmorillonite, and illite. In all cases, frictional strengths of mixtures fall between the end-members of pure quartz (strongest) and clay (weakest). The overall trend was a decrease in strength with increasing clay content. In the illite/quartz mixture the trend was nearly linear, while in the montmorillonite mixtures a sigmoidal trend with three strength regimes was noted. Microstructural observations were performed on the deformed samples to characterize the geometric attributes of shear localization within the gouge layers. Two micromechanical models were used to analyze the critical clay fractions for the two-regime transitions on the basis of clay porosity and packing of the quartz grains. The transition from regime 1 (high strength) to 2 (intermediate strength) is associated with the shift from a stresssupporting framework of quartz grains to a clay matrix embedded with disperse quartz grains, manifested by the development of P-foliation and reduction in Riedel shear angle. The transition from regime 2 (intermediate strength) to 3 (low strength) is attributed to the development of shear localization in the clay matrix, occurring only when the neighboring layers of quartz grains are separated by a critical clay thickness. Our mixture data relating strength degradation to clay content agree well with strengths of natural shear zone materials obtained from scientific deep drilling projects. Copyright 2010 by the American Geophysical Union.

Brucherseifer M.,Karlsruhe Institute of Technology | Caola F.,Johns Hopkins University | Melnikov K.,Johns Hopkins University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We present O(αs 2) QCD corrections to the fully-differential decay rate of a b-quark into inclusive semileptonic charmless final states. Our calculation provides genuine two-loop QCD corrections, beyond the Brodsky-Lepage-Mackenzie (BLM) approximation, to any infra-red safe partonic observable that can be probed in b→Xueν decays. Kinematic cuts that closely match those used in experiments can be fully accounted for. To illustrate these points, we compute the non-BLM corrections to moments of the hadronic invariant mass and the hadronic energy with cuts on the lepton energy and the hadronic invariant mass. Our results remove one of the sources of theoretical uncertainty that affect the extraction of the CKM matrix element |Vub| from charmless inclusive B decays. © 2013 Elsevier B.V.

Ulrich T.,Karlsruhe Institute of Technology
Metrologia | Year: 2013

Laser trackers are widely used to measure kinematic tasks such as tracking robot movements. Common methods to evaluate the uncertainty in the kinematic measurement include approximations specified by the manufacturers, various analytical adjustment methods and the Kalman filter. In this paper a new, real-time technique is proposed, which estimates the 4D-path (3D-position + time) uncertainty of an arbitrary path in space. Here a hybrid system estimator is applied in conjunction with the kinematic measurement model. This method can be applied to processes, which include various types of kinematic behaviour, constant velocity, variable acceleration or variable turn rates. The new approach is compared with the Kalman filter and a manufacturer's approximations. The comparison was made using data obtained by tracking an industrial robot's tool centre point with a Leica laser tracker AT901 and a Leica laser tracker LTD500. It shows that the new approach is more appropriate to analysing kinematic processes than the Kalman filter, as it reduces overshoots and decreases the estimated variance. In comparison with the manufacturer's approximations, the new approach takes account of kinematic behaviour with an improved description of the real measurement process and a reduction in estimated variance. This approach is therefore well suited to the analysis of kinematic processes with unknown changes in kinematic behaviour as well as the fusion among laser trackers. © 2013 BIPM & IOP Publishing Ltd.

Nick P.,Karlsruhe Institute of Technology
Plant Cell Monographs | Year: 2014

Plant microtubules have evolved into a versatile tool to link environmental signals into flexible morphogenesis. Cortical microtubules define the axiality of cell expansion by control of cellulose orientation. Plant-specific microtubule structures such as preprophase band and phragmoplast determine symmetry and axiality of cell divisions. In addition, microtubules act as sensors and integrators for stimuli such as mechanic load and gravity but also osmotic stress, cold, and pathogen attack. Many of these functions are specific for plants and involve unique proteins or the recruitment of proteins to new functions. The review aims to ventilate the potential of microtubule-based strategies for biotechnological application by highlighting representative case studies. These include reorientation of cortical microtubules to increase lodging resistance, control of microtubule dynamics to alter the gravity-dependent orientation of leaves, the use of microtubules as sensitive thermometers to improve adaptive cold tolerance of chilling and freezing sensitive plants, the reduction of microtubule treadmilling to inhibit cell-to-cell transport of plant viruses, or the modulation of plant defence genes by pharmacological manipulation of microtubules. The specificity of these responses is controlled by a great variety of specific associated proteins opening a wide field for biotechnological manipulation of plant architecture and stress tolerance. © Springer-Verlag Berlin Heidelberg 2014.

Zilberberg O.,Weizmann Institute of Science | Romito A.,Karlsruhe Institute of Technology | Romito A.,Free University of Berlin | Gefen Y.,Weizmann Institute of Science
Physical Review Letters | Year: 2011

A protocol employing weak values (WVs) to obtain ultrasensitive amplification of weak signals in the context of a solid-state setup is proposed. We consider an Aharonov-Bohm interferometer where both the orbital and the spin degrees of freedom are weakly affected by the presence of an external charge to be detected. The interplay between the spin and the orbital WVs leads to a significant amplification even in the presence of finite temperature, voltage, and external noise. © 2011 American Physical Society.

Rieth M.,Karlsruhe Institute of Technology | Hoffmann A.,Plansee Group
International Journal of Refractory Metals and Hard Materials | Year: 2010

Refractory materials, in particular tungsten base materials are considered as primary candidates for high heat load applications in future nuclear fusion power plants. Promising design outlines make use of the high heat conductivity and strength of W-1%La 2O 3 (WL10) as structural material. Here, the lower temperature range is restricted by the transition to a steel part and the upper operation temperature limit is defined by the onset of recrystallization and/or loss of strength, respectively. The most critical issue of tungsten materials in connection with structural applications, however, is the ductile-to-brittle transition. Another problem consists in the fact that especially refractory alloys show a strong correlation between microstructure and their manufacturing history. Since mechanical properties are defined by the underlying microstructure, refractory alloys can behave quite different, even if their chemical composition is the same. Therefore, the fracture behavior of several tungsten based alloys was characterized by standard Charpy tests which have been performed up to 1100 °C in vacuum. Due to their fabrication history (powder mixing, pressing, sintering, rolling or swaging) all materials had specific microstructures which often led to typical delamination fractures. The influence of the microstructure characteristics like grain size, anisotropy, texture, or chemical composition as well as the effect of notch machining was investigated. All results are discussed and assessed with respect to the optimization of future component fabrication for high temperature nuclear fusion applications. © 2010 Elsevier Ltd. All rights reserved.

Akgul G.,Suleyman Demirel University of Turkey | Kruse A.,Karlsruhe Institute of Technology
Journal of Supercritical Fluids | Year: 2012

The water-gas shift reaction is the key reaction to produce hydrogen by hydrothermal biomass gasification. Salts are ingredients of biomass and accelerate the water-gas shift reaction. In this work, the influences of the NaHCO 3 and the KHCO 3 on water-gas shift reaction (WGSR) were investigated at 10 and 23 MPa and 230-300°C. The presence of NaHCO 3 and KHCO 3 promotes the WGSR significantly and to the same extend. Additionally, sodium and potassium formate salts are formed from the carbonates. The water-gas shift reaction rate in the presence of salts is found to be:1.16×104(lmol-1)0.5s-1e(-9155K/T)CONaHCO30.5. © 2011 Elsevier B.V.

King S.F.,University of Southampton | Muhlleitner M.,Karlsruhe Institute of Technology | Nevzorov R.,University of Hawaii at Manoa
Nuclear Physics B | Year: 2012

The recent LHC indications of a SM-like Higgs boson near 125 GeV are consistent not only with the Standard Model (SM) but also with Supersymmetry (SUSY). However naturalness arguments disfavour the Minimal Supersymmetric Standard Model (MSSM). We consider the Next-to-Minimal Supersymmetric Standard Model (NMSSM) with a SM-like Higgs boson near 125 GeV involving relatively light stops and gluinos below 1 TeV in order to satisfy naturalness requirements. We are careful to ensure that the chosen values of couplings do not become non-perturbative below the grand unification (GUT) scale, although we also examine how these limits may be extended by the addition of extra matter to the NMSSM at the two-loop level. We then propose four sets of benchmark points corresponding to the SM-like Higgs boson being the lightest or the second lightest Higgs state in the NMSSM or the NMSSM-with-extra-matter. With the aid of these benchmark points we discuss how the NMSSM Higgs boson near 125 GeV may be distinguished from the SM Higgs boson in future LHC searches. © 2012.

Fernandes R.M.,University of Minnesota | Maiti S.,University of Wisconsin - Madison | Wolfle P.,Karlsruhe Institute of Technology | Chubukov A.V.,University of Wisconsin - Madison
Physical Review Letters | Year: 2013

Recent experiments on two iron-pnictide families suggest the existence of a single quantum phase transition inside the superconducting dome despite the fact that two separate transition lines - magnetic and nematic - cross the superconducting dome at Tc. Here we argue that these two observations are actually consistent. We show, using a microscopic model, that each order coexists with superconductivity for a wide range of parameters, and both transition lines continue into the superconducting dome below Tc. However, at some Tmerge

Reimert R.,Karlsruhe Institute of Technology
Nuclear Engineering and Design | Year: 2012

In a comprehensive study Lurgi GmbH and Interatom GmbH, both of Germany, analyzed to which extent and for which industries process heat supply by modularized HTR might be realized, and which adaptation work, both on the reactor and on the process side would be necessary. Refining operations and alumina calcination appeared as the most promising candidates for the use of HTR process heat. In refineries the temperature level is mostly well below 600 °C, and the heat flow amounts to some 100 MW. Adaptation work would only be necessary for heat exchangers and for the safety concept. In the case of alumina calcination the heat flow is in the same order of magnitude but the peak temperature of 950-1000 °C is a little bit above the range in which the HTR can supply heat. Adaptation work would be needed for new heat exchangers and for process modifications with the aim of either lowering the process' peak temperature or providing the heat at peak temperature via a clean chemical fuel. Consequently, in the second part of the study these adaptation works were addressed, and technically and economic feasible solutions were found. © 2011 Elsevier B.V.

Dierlamm A.,Karlsruhe Institute of Technology
Journal of Instrumentation | Year: 2012

Preparing for the high-luminosity phase of LHC the CMS Tracker collaboration has started a campaign to identify the future planar silicon sensor technology baseline for a new Tracker. A variety of 6 inch wafers have been ordered in different thicknesses and technologies at HPK. Thicknesses ranging from 50μm to 300μm are explored on float-zone, magnetic Czochralski and epitaxial material both in n-in-p and p-in-n versions. p-stop and p-spray are explored as isolation technologies for the n-in-p type sensors as well as the feasibility of double metal routing on 6 inch wafers. To explore the limits of the technologies many different structures have been designed to answer different questions, e.g. geometry, Lorentz angle, radiation tolerance, annealing behavior, read-out schemes. This contribution provides an overview of the individual structures and their characteristics and summarizes measurements done on small strip sensors before and after irradiations. © 2012 IOP Publishing Ltd and SISSA.

Wedig W.V.,Karlsruhe Institute of Technology
Probabilistic Engineering Mechanics | Year: 2012

This paper investigates dynamics of roadvehicle systems via stochastic numerics, applying discrete integration schemes of first and second order. The ride on rough roads generates vertical car vibrations whose root mean squares become resonant for critical speeds. The investigations are extended to nonlinear wheel suspensions with cubicprogressive springs. For weak but still positive damping, the car vibrations become unstable in overcritical speed ranges detected by means of perturbation equations whose top Lyapunov exponent can become positive in the case of parameter resonances. This indicates that the stationary car vibrations bifurcate into stochastic chaos. © 2011 Elsevier Ltd. All rights reserved.

Jakob W.,Karlsruhe Institute of Technology
Memetic Computing | Year: 2010

As memetic algorithms (MA) are a crossbreed between local searchers and evolutionary algorithms (EA) spreading of computational resources between evolutionary and local search is a key issue for a good performance, if not for success at all. This paper summarises and continues previous work on a general cost-benefit-based adaptation scheme for the choice of local searchers (memes), the frequency of their usage, and their search depth. This scheme eliminates the MA strategy parameters controlling meme usage, but raises new ones for steering the adaptation itself. Their impact is analysed and it will be shown that in the end the number of strategy parameters is decreased significantly as well as their range of meaningful values. In addition to this the number of fitness evaluations is reduced drastically. Both are necessary prerequisites for many practical applications as well as for the acceptance of the method by practitioners. Although the introduced framework is tailored to EAs producing more than one offspring per mating, it is also suited for those with only one child per pairing. So there are no preconditions to the EA for the described adaptation scheme to be applied. © 2010 Springer-Verlag.

Sepelak V.,Karlsruhe Institute of Technology | Sepelak V.,Leibniz University of Hanover | Duvel A.,Leibniz University of Hanover | Wilkening M.,University of Graz | And 3 more authors.
Chemical Society Reviews | Year: 2013

Technological and scientific challenges coupled with environmental considerations have prompted a search for simple and energy-efficient syntheses and processing routes of materials. This tutorial review provides an overview of recent research efforts in non-conventional reactions and syntheses of oxides induced by mechanical action. It starts with a brief account of the history of mechanochemistry. Ensuing discussions will review the progress in homogeneous and heterogeneous mechanochemical reactions in oxides of various structures. The review demonstrates that the event of mechanically induced reactions provides novel opportunities for the non-thermal manipulation of materials and for the tailoring of their properties. © 2013 The Royal Society of Chemistry.

Walther C.,Leibniz University of Hanover | Denecke M.A.,Karlsruhe Institute of Technology
Chemical Reviews | Year: 2013

A study was conducted to investigate actinide colloids and particles of environmental concern. Sources of actinide particles in the environment other than nuclear explosions and nuclear power plant accidents were naturally occurring radioactive matter or particle contaminants released from other military activities related to nuclear power production and from minor occurrences, such as nuclear powered satellites. These particles containing actinide element contaminants were found in the environment in a wide variety of forms or morphologies and compositions, exhibiting varying chemistries and stabilities. The morphology, elemental, and isotopic composition of actinide particles were obtained by a variety of experimental techniques, such as electron microscopy, mass spectrometry (MS), and some other techniques.

Hussain H.,University of Paderborn | Hussain H.,The University of Nizwa | Green I.R.,Stellenbosch University | Ahmed I.,Karlsruhe Institute of Technology
Chemical Reviews | Year: 2013

The various synthetic methods discussed in this review reveal that Oxone is a versatile reagent used in organic synthesis. Oxone is a cheap commercially available oxidant that easily oxidizes numerous functional groups. It is an efficient single oxygen-atom donor since it contains a nonsymmetrical O-O bond which is heterolytically cleaved during the oxidation cycle. It is an inexpensive reagent ($0.02-0.04/g), which compares favorably with hydrogen peroxide and bleach. Its byproducts do not pose an immediate threat to aquatic life upon disposal, and unlike chromium trioxide and bleach, it does not emit pungent vapors or pose a serious inhalation risk. The aqueous components of an organic Oxone reaction are oxidizing and acidic and should thus be quenched with sodium bisulfite followed by neutralization with sodium bicarbonate, thereby resulting in formation of a mixture of nonhazardous sulfate salts in water. These features make Oxone attractive for large-scale applications. Uses of other oxidizing agents lack the desired ingredients to attract the interest of industry because of tedious purification processes from their deoxygenated counterparts. The dioxirane (generated from reaction between Oxone and a ketone) epoxidation offers many advantages over traditional methods of epoxidation. Oxone is about one-half as expensive as m-chloroperoxybenzoic acid (mCPBA) and converted to KHSO4. KHSO4 during the reaction, while being relatively acidic, can easily be neutralized with dilute NaOH solution to produce nontoxic Na2SO4. Furthermore, the reaction conditions require the use of relatively nontoxic organic solvents plus water. Another advantage of dioxirane epoxidation is that acetone is recycled in the reaction, which means all of the extra oxygen in Oxone is incorporated into the respective alkenes. Dioxirane is also capable of oxidizing very unreactive olefins, and thus, isolation of some relatively unstable epoxides produced from glycals is possible. This represents a major advantage over the Sharpless and mCPBA protocols, which only epoxidize electron-rich olefins and allylic or homoallylic alcohols. These latter reagents also require a directing group. One drawback that dioxirane does have is the fact that it can also oxidize very reactive heteroatoms, hydroxyl groups, and unactivated C-H bonds during the epoxidation procedure. Oxone does have some disadvantages: (a) it is insoluble in organic solvents, (b) buffering is needed due to its acidity, and (c) it sometimes bleaches the metal catalysts and donor ligands during oxidation reactions. To overcome the need for aqueous conditions, some authors have used ionic liquids as solvent, and additionally, several tetraalkylammonium salts of Oxone have been reported. It has been found that when the cation in Oxone (i.e., K+) is changed to, e.g., n-Bu4N+, the oxidant also shows higher solubility in organic solvents, especially in dichloromethane. Tactical utilization of Oxone in synthetic plans is that it may replace tedious organic transformations with simpler routes. One other drawback which needs to be mentioned is that a relatively large excess of Oxone may be required in some reactions to consume all of the starting material. However, militating against this is that Oxone can be reused when it is in stoichiometric excess. Owing to the discovery of a variety of novel applications, Oxone is becoming an increasingly important reagent in synthetic organic chemistry. We hope that this review may act as a catalyst in boosting applications of Oxone in organic synthesis.

Rotzler J.,University of Basel | Mayor M.,University of Basel | Mayor M.,Karlsruhe Institute of Technology
Chemical Society Reviews | Year: 2013

This tutorial review summarizes the progress made towards mechanically interlocked daisy chains. Such materials can be seen as a further development in polymer science, where the conventional covalent interlinking bonds are replaced by supramolecular binding concepts. Materials in which the mechanical bond is an integral part of the polymeric backbone are expected to possess unique macroscopic properties and are therefore the synthetic aim in an ever growing research community. After introducing general considerations about daisy chains, the most common analytic methods to get insight into the aggregation behaviour of such self-complementary monomers are presented. Cyclodextrins/aromatic rods, crown ethers/cationic rods and pillararenes/alkyl chains are systems used to achieve daisy chain-like molecular arrays. By comparison of the reported systems, conclusions about an improved structural design are drawn.

Rothengatter W.,Karlsruhe Institute of Technology
Transportation Research Part D: Transport and Environment | Year: 2010

There is a world-wide consensus that climate change policy has to be intensified to achieve reduction goals set for 2020 and 2050. But it is heavily debated which contribution should be expected from the transport sector. It is often argued that in the transportation sector CO2 marginal mitigation costs are higher such that - together with high growth of transport activities - the reduction targets for this sector should be relaxed. Green transport policy is contrasting this view and underlines that considerable reductions of climate gases in the transport sector are possible without risking economic prosperity. The aviation industry is in the focus of this discussion and first attempts are being made in the European Union to integrate aviation in an emission trading system. It will be shown that the impact of this policy will be very low in the medium term and that additional measures are necessary to create enough incentives for the aviation industry to exploit their reduction potential. © 2009.

Mallick B.,Karlsruhe Institute of Technology
Disasters | Year: 2014

Bangladesh is one of the poorest and the most disaster-prone countries in Asia; it is important, therefore, to know how its disaster reduction strategies are organised and planned. Cyclone shelters comprise a widely acceptable form of infrastructural support for disaster management in Bangladesh. This paper attempts to analyse empirically their use during cyclones in a sample study area along the southwest coastal belt of the country. It shows how the location of a cyclone shelter can determine the social power structure in coastal Bangladesh. The results reveal that the establishment of cyclone shelters in the studied communities is determined by neither a right-based nor a demand-based planning approach; rather, their creation is dependent on the socio-political affluence of local-level decision-makers. The paper goes on to demonstrate that socially vulnerable households (defined, for example, by income or housing conditions) are afforded disproportionately less access to cyclone shelters as compared to less socially vulnerable households. © 2014 The Author(s).

Vehlow J.,Karlsruhe Institute of Technology
Waste Management | Year: 2015

All WtE (waste-to-energy) plants, based on combustion or other thermal processes, need an efficient gas cleaning for compliance with legislative air emission standards. The development of gas cleaning technologies started along with environment protection regulations in the late 1960s. Modern APC (air pollution control) systems comprise multiple stages for the removal of fly ashes, inorganic and organic gases, heavy metals, and dioxins from the flue gas. The main technologies and devices used for abatement of the various pollutants are described and their basic principles, their peculiarities, and their application are discussed. Few systems for cleaning of synthesis gas from waste gasification plants are included. Examples of APC designs in full scale plants are shown and cautious prospects for the future development of APC systems are made. © 2014 Elsevier Ltd.

Campanario F.,University of Valencia | Rauch M.,Karlsruhe Institute of Technology | Sapeta S.,Durham University
Nuclear Physics B | Year: 2014

Pair production of W gauge bosons is an important process at the LHC entering many experimental analyses, both as background in new-physics searches or Higgs measurements and as signal in precision studies and tests of the Standard Model. Therefore, accurate predictions for this class of processes are of great interest in order to exploit the full potential of LHC measurements. We use the LoopSim method to combine NLO QCD results for WW and WW. +. jet, as well as the loop-squared gluon-fusion contribution, to obtain approximate NNLO predictions for WW production. The cross sections are calculated with VBFNLO and include leptonic decays of the W bosons as well as finite-width and off-shell effects. We find that the size of the additional corrections beyond NLO can be significant and well outside of the NLO error bands given by renormalization and factorization scale variation. Applying a jet veto, we observe further negative corrections at NNLO, which we relate to the presence of large Sudakov logarithms. © 2013 The Authors.

Scheurer M.S.,Karlsruhe Institute of Technology
Physical Review B - Condensed Matter and Materials Physics | Year: 2016

We analyze the possible interaction-induced superconducting instabilities in noncentrosymmetric systems based on symmetries of the normal state. It is proven that pure electron-phonon coupling will always lead to a fully gapped superconductor that does not break time-reversal symmetry and is topologically trivial. We show that topologically nontrivial behavior can be induced by magnetic doping without gapping out the resulting Kramers pair of Majorana edge modes. In the case of superconductivity arising from the particle-hole fluctuations associated with a competing instability, the properties of the condensate crucially depend on the time-reversal behavior of the order parameter of the competing instability. When the order parameter preserves time-reversal symmetry, we obtain exactly the same properties as in the case of phonons. If it is odd under time reversal, the Cooper channel of the interaction will be fully repulsive leading to sign changes of the gap and making spontaneous time-reversal-symmetry breaking possible. To discuss topological properties, we focus on fully gapped time-reversal-symmetric superconductors and derive constraints on possible pairing states that yield necessary conditions for the emergence of topologically nontrivial superconductivity. These conditions might serve as a tool in the search for topological superconductors. We also discuss implications for oxide heterostructures and single-layer FeSe. © 2016 American Physical Society.

Lutzenkirchen J.,Karlsruhe Institute of Technology
Applied Geochemistry | Year: 2012

This paper summarizes the activities within the European project FUNMIG (FUNdamental Processes of Radionuclide MIGration) concerned with sorption as a " well-established" process. Within FUNMIG, many, if not all, work-packages in some way involved sorption processes. In order to avoid repetition within this special issue and to have a clear separation, the present contribution only gives an impression of the work done within the one particular work-package with the above title. The various subprojects from that work-package were regrouped into studies on model sorbents, on sorbents directly pertaining to host rock formations and on studies primarily concerned with sorption. For each of the issues a short summary with an aspect that may be of particular interest to readers from outside the nuclear waste community is given. The work on sorption covers experimental and modeling work on model sorbents (silica and alumina), sorbents related to the engineered barrier (clay minerals) and identified host rock formation related sorbents (clay minerals in France, Switzerland and Belgium; granite in Sweden and Finland). Experimental and modeling results on these systems are addressed in some detail. Pure modeling studies on database building and evaluation of highly simplified adsorption models were also carried out and these will be discussed along with a suggestion to relate a model to a certain purpose to facilitate justification of the model approach chosen. © 2011 Elsevier Ltd.

Klinkhamer F.R.,Karlsruhe Institute of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

A finite-energy static classical solution is obtained for standard Einstein gravity coupled to an SO(3)×SO(3) chiral model of scalars (a Skyrme model). This nonsingular localized solution has nontrivial topology for both the spacetime manifold and the SO(3) matter fields. The solution corresponds to a single spacetime defect embedded in flat Minkowski spacetime. © 2014 American Physical Society.

Silvestrini M.,University of Venice | Fruk L.,Karlsruhe Institute of Technology | Ugo P.,University of Venice
Biosensors and Bioelectronics | Year: 2013

A novel electrochemical biosensor for DNA hybridization detection based on nanoelectrode ensembles (NEEs) is presented. NEEs are prepared by electroless deposition of gold into the pores of a templating track-etched polycarbonate (PC) membrane. The wide surface of the templating membrane surrounding the nanoelectrodes is exploited to bind the capture DNA probes via amide coupling with the carboxylic groups present on the PC surface. The probes are then hybridized with the complementary target labelled with glucose oxidase (GOx). The occurrence of the hybridization event is detected by adding, to the supporting electrolyte, excess glucose as the substrate and the (ferrocenylmethyl) trimethylammonium cation (FA+) as suitable redox mediator. In the case of positive hybridization, an electrocatalytic current is detected. In the proposed sensor, the biorecognition event and signal transduction occur in different but neighbouring sites, i.e., the PC surface and the nanoelectrodes, respectively; these sites are separated albeit in close proximity on a nanometer scale. Finally, the possibility to activate the PC surface by treatment with permanganate is demonstrated and the analytical performances of biosensors prepared with KMnO4-treated NEEs and native NEEs are compared and critically evaluated. The proposed biosensor displays high selectivity and sensitivity, with the capability to detect few picomoles of target DNA. © 2012 Elsevier B.V.

Kruse A.,Karlsruhe Institute of Technology | Kruse A.,University of Hohenheim | Funke A.,Leibniz Institute for Agricultural Engineering | Titirici M.-M.,Queen Mary, University of London
Current Opinion in Chemical Biology | Year: 2013

Available biomass, preferentially residues, can be divided in two groups: biomass with a high or natural water content ('wet' or 'green' biomass) and biomass with low water content such as wood and straw. In 'dry' biomass gasification processes, originating in most coal processing technologies, biomass of low water content is necessary to avoid the energy loss by water evaporation. In contrast, hydrothermal processes need water as reaction medium; therefore, these processes are preferentially used for wet or 'green' biomass.In this review paper we will describe the main research directions in the hydrothermal conversion of biomass into fuels and carbon throughout gasification to produce H2 or CH4, liquefaction to produce crude oils and phenols from lignin as well as carbonization to produce carbonaceous materials which can be either used as fuels (carbon negative chars) or interesting energetic materials (hydrothermal carbons). © 2013 Elsevier Ltd.

Cui Q.,University of Wisconsin - Madison | Elstner M.,Karlsruhe Institute of Technology
Physical Chemistry Chemical Physics | Year: 2014

Semi-empirical (SE) methods are derived from Hartree-Fock (HF) or Density Functional Theory (DFT) by neglect and approximation of electronic integrals. Thereby, parameters are introduced which have to be determined from reference calculations and/or by fitting to available experimental data. This leads to computational methods that are about 2-3 orders of magnitude faster than the standard HF/DFT methods using medium sized basis sets while being about 3 orders of magnitude slower than empirical force field methods (Molecular Mechanics: MM). Therefore, SE methods are most appropriate for a specific range of applications. These include the study of systems that contain a large number of atoms and therefore being too large for ab initio or DFT methods and also problems where dynamic or entropic effects are particularly important. In the latter case, the errors made by considering a very limited number of molecular structures or neglecting entropic contributions can be much larger than the accuracy lost due to the use of SE methods. Another area where SE methods are attractive concerns the analysis of systems for which reliable MM models are not readily available. Therefore, even in an era when rapid progress is being made in ab initio methods, there is considerable interest in further developing SE methods. We illustrate this point by focusing on the discussion of recent development and application of the Density Functional Tight Binding method. © the Partner Organisations 2014.

Sleeman J.P.,University of Heidelberg | Sleeman J.P.,Karlsruhe Institute of Technology
Cancer and Metastasis Reviews | Year: 2012

The tumor stroma is comprised of extracellular matrix, non-malignant cells, and the signaling molecules they produce. It is an integral and vital component of primary tumors that together with the underlying genetic defects in the tumor cells determines the growth characteristics, morphology, and invasiveness of the tumor. In parallel to continuing genetic changes in the tumor cells themselves, the tumor stroma progressively evolves during primary tumor development. Cancer cells that disseminate from primary tumors are dependent on this stromal microenvironment, and therefore the microenvironment they encounter at secondary sites determines their fate. For those cells that survive at these sites, stromal progression can serve to re-establish a supportive tumor stroma, fostering the outgrowth of the cells as metastases. Formation of a metastatic niche that supports the survival and growth of disseminated tumor cells is a key feature of this stromal progression. The endogenous organ microenvironment can provide components of the metastatic niche. In addition, microenvironmental changes in organs prior to receipt of disseminated tumor cells can be induced by factors secreted systemically by primary tumors, causing the formation of pre-metastatic niches. Further maturation of metastatic niches can be responsible for the re-activation of dormant disseminated tumor cells many years after removal of the primary tumor. The concept of the metastatic niche and stromal progression has profound consequences for our understanding of metastatic disease, and promises to open up new strategies for the diagnosis, prognostic evaluation, and therapy of cancer. © 2012 The Author(s).

Wittmann C.,Karlsruhe Institute of Technology
Journal of visualized experiments : JoVE | Year: 2012

Zebrafish larvae are particularly amenable to whole animal small molecule screens due to their small size and relative ease of manipulation and observation, as well as the fact that compounds can simply be added to the bathing water and are readily absorbed when administered in a <1% DMSO solution. Due to the optical clarity of zebrafish larvae and the availability of transgenic lines expressing fluorescent proteins in leukocytes, zebrafish offer the unique advantage of monitoring an acute inflammatory response in vivo. Consequently, utilizing the zebrafish for high-content small molecule screens aiming at the identification of immune-modulatory compounds with high throughput has been proposed, suggesting inflammation induction scenarios e.g. localized nicks in fin tissue, laser damage directed to the yolk surface of embryos or tailfin amputation. The major drawback of these methods however was the requirement of manual larva manipulation to induce wounding, thus preventing high-throughput screening. Introduction of the chemically induced inflammation (ChIn) assay eliminated these obstacles. Since wounding is inflicted chemically the number of embryos that can be treated simultaneously is virtually unlimited. Temporary treatment of zebrafish larvae with copper sulfate selectively induces cell death in hair cells of the lateral line system and results in rapid granulocyte recruitment to injured neuromasts. The inflammatory response can be followed in real-time by using compound transgenic cldnB::GFP/lysC::DsRED2 zebrafish larvae that express a green fluorescent protein in neuromast cells, as well as a red fluorescent protein labeling granulocytes. In order to devise a screening strategy that would allow both high-content and high-throughput analyses we introduced robotic liquid handling and combined automated microscopy with a custom developed software script. This script enables automated quantification of the inflammatory response by scoring the percent area occupied by red fluorescent leukocytes within an empirically defined area surrounding injured green fluorescent neuromasts. Furthermore, we automated data processing, handling, visualization, and storage all based on custom developed MATLAB and Python scripts. In brief, we introduce an automated HC/HT screen that allows testing of chemical compounds for their effect on initiation, progression or resolution of a granulocytic inflammatory response. This protocol serves a good starting point for more in-depth analyses of drug mechanisms and pathways involved in the orchestration of an innate immune response. In the future, it may help identifying intolerable toxic or off-target effects at earlier phases of drug discovery and thereby reduce procedural risks and costs for drug development.

Lutzenkirchen J.,Karlsruhe Institute of Technology
Langmuir | Year: 2013

Experimental results on specific ion effects at the c- and r- single-crystal planes of sapphire obtained by zeta-potential measurements at pH 5.8 are reported. Both crystal planes have negative electrokinetic charge at pH 5.8 and their intrinsic isoelectric points are found close to pH 4. The water structure "making" surface (i.e., r-plane, based on surface diffraction and surface complexation modeling) causes cation specificity in the order Li+ > Na+ > K+ > Rb+ > Cs+ in chloride systems while no anion sensitivity occurs in sodium systems (Cl-, NO3 -, and BrO 3 -) as expected. The cation series concurs with the simple idea of structure making ions being adsorbed more strongly on structure making surfaces and also concurs with the sequence found for particulate alumina for the cation series in nitrate systems. On the structure breaking basal plane (i.e., c-plane, again based on surface diffraction and surface complexation modeling), no cation specific effects are observed in chloride systems, but the structure breaking properties are retrieved in the cation series in nitrate systems. Surprisingly, anion specificity is observed on sapphire-c. Furthermore, the chloride ion shows unexpected behavior that suggests chloride adsorption onto the negatively charged surface. Based on these experimental observations in conjunction with generic results from published MD simulations, the c-plane sapphire aqueous electrolyte interface is a nonpolar surface with negative charge. The nonpolarity finds repercussions in the weak water ordering and the observed ion specific effects. The low isoelectric points of the cuts cannot be explained by the respective surface chemistries of the ideal surfaces. Relation to "inert" surfaces and concomitant dominance of hydroxide ion adsorption is a possible explanation for the low isoelectric points of both cuts. The reported ion specific effects occur at concentrations below 10 mM. Overall, the results support the idea that ion specific effects are largely governed by surface hydration. © 2013 American Chemical Society.

Integration by parts identities (IBPs) can be used to express large numbers of apparently different d-dimensional Feynman Integrals in terms of a small subset of so-called master integrals (MIs). Using the IBPs one can moreover show that the MIs fulfil linear systems of coupled differential equations in the external invariants. With the increase in number of loops and external legs, one is left in general with an increasing number of MIs and consequently also with an increasing number of coupled differential equations, which can turn out to be very difficult to solve. In this paper we show how studying the IBPs in fixed integer numbers of dimension d = n with n∈N one can extract the information useful to determine a new basis of MIs, whose differential equations decouple as d→n and can therefore be more easily solved as Laurent expansion in (d-n). © 2015 The Author.

Kuchenmeister J.,Karlsruhe Institute of Technology
Optics Express | Year: 2014

The concepts of adaptive coordinates and adaptive spatial resolution have proved to be a valuable tool to improve the convergence characteristics of the Fourier Modal Method (FMM), especially for metallo-dielectric systems. Yet, only two-dimensional adaptive coordinates were used so far. This paper presents the first systematic construction of three-dimensional adaptive coordinate and adaptive spatial resolution transformations in the context of the FMM. For that, the construction of a three-dimensional mesh for a periodic system consisting of two layers of mutually rotated, metallic crosses is discussed. The main impact of this method is that it can be used with any classic FMM code that is able to solve the large FMM eigenproblem. Since the transformation starts and ends in a Cartesian mesh, only the transformed material tensors need to be computed and entered into an existing FMM code. © 2014 Optical Society of America.

Kuhr T.,Karlsruhe Institute of Technology
Journal of Physics: Conference Series | Year: 2014

The next generation B factory experiment Belle II will collect huge data samples which are a challenge for the computing system. To cope with the high data volume and rate, Belle II is setting up a distributed computing system based on existing technologies and infrastructure plus Belle II specific extensions for workflow abstraction. The system was successfully tested in two production campaigns this year and valuable information for the further development was obtained.

Werner K.,University of Nantes | Karpenko Iu.,NASU Bogolyubov Institute for Theoretical Physics | Pierog T.,Karlsruhe Institute of Technology
Physical Review Letters | Year: 2011

One of the most important experimental results for proton-proton scattering at the LHC is the observation of a so-called "ridge" structure in the two-particle correlation function versus the pseudorapidity difference Δη and the azimuthal angle difference Δφ. One finds a strong correlation around Δφ=0, extended over many units in Δη. We show that a hydrodynamical expansion based on flux tube initial conditions leads in a natural way to the observed structure. To get this result, we have to perform an event-by-event calculation, because the effect is due to statistical fluctuations of the initial conditions, together with a subsequent collective expansion. This is a strong point in favor of a fluidlike behavior even in pp scattering, where we have to deal with length scales of the order of 0.1 fm. © 2011 American Physical Society.

Fischer R.,Karlsruhe Institute of Technology
Chemistry and Biology | Year: 2014

Secondary metabolites are often highly biologically active molecules and are widely used from antibacterial to anticancer drugs. In this issue of Chemistry and Biology, Zaehle and coworkers describe the gene cluster and biosynthesis of the polyketide terrein, a secondary metabolite produced by the soil-borne fungus Aspergillus terreus. © 2014 Elsevier Ltd.

Spanu P.,Imperial College London | Kamper J.,Karlsruhe Institute of Technology
Current Opinion in Plant Biology | Year: 2010

We are on the verge of a flood of new genome data from a plethora of plant pathogens. Although the data are just beginning to be analysed systematically and to be published, there are emerging patterns associated with pathogenicity and biotrophy. The expansion of protein families with functions required for host infection is found in most pathogens; in addition, we see specific adaptations of the biotrophs, as the reduction of proteins involved in plant cell-wall degradation, or a specialization in carbon utilization that avoids plant responses. The expansion of genomes by repeated elements and the resulting genome dynamics are thought to be one of the driving forces for the fast evolution of pathogenicity factors, resulting in an adaptive advantage to the changing hostile environment of the plant host. © 2010 Elsevier Ltd.

Grimm V.,Karlsruhe Institute of Technology
BIT Numerical Mathematics | Year: 2012

We consider the approximation of operator functions in resolvent Krylov subspaces. Besides many other applications, such approximations are currently of high interest for the approximation of φ-functions that arise in the numerical solution of evolution equations by exponential integrators. It is well known that Krylov subspace methods for matrix functions without exponential decay show superlinear convergence behaviour if the number of steps is larger than the norm of the operator. Thus, Krylov approximations may fail to converge for unbounded operators. In this paper, we analyse a rational Krylov subspace method which converges not only for finite element or finite difference approximations to differential operators but even for abstract, unbounded operators whose field of values lies in the left half plane. In contrast to standard Krylov methods, the convergence will be independent of the norm of the discretised operator and thus of the spatial discretisation. We will discuss efficient implementations for finite element discretisations and illustrate our analysis with numerical experiments. © 2011 Springer Science + Business Media B.V.

Hackstein C.,Karlsruhe Institute of Technology | Spannowsky M.,University of Oregon
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

Searches for a heavy standard model Higgs boson focus on the "gold plated mode" where the Higgs decays to two leptonic Z bosons. This channel provides a clean signature, in spite of the small leptonic branching ratios. We show that using fat jets the semileptonic ZZ mode significantly increases the number of signal events with a similar statistical significance as the leptonic mode. © 2010 The American Physical Society.

Wolfle P.,Karlsruhe Institute of Technology | Dubi Y.,Los Alamos National Laboratory | Balatsky A.V.,Los Alamos National Laboratory
Physical Review Letters | Year: 2010

Recently observed tunneling spectra on clean heavy-fermion compounds show a lattice periodic Fano line shape similar to what is observed in the case of tunneling to a Kondo ion adsorbed at the surface. We show that the translation symmetry of a clean surface in the case of weakly correlated metals leads to a tunneling spectrum which shows a hybridization gap but does not have a Fano line shape. By contrast, in a strongly correlated heavy-fermion metal the heavy quasiparticle states will be broadened by interaction effects. The hybridization gap is completely filled in this way, and an ideal Fano line shape of width ∼2TK results. In addition, we discuss the possible influence of the tunneling tip on the surface, in (i) leading to additional broadening of the Fano line and (ii) enhancing the hybridization locally, hence adding to the impurity type behavior. The latter effects depend on the tip-surface distance. © 2010 The American Physical Society.

Von Clarmann T.,Karlsruhe Institute of Technology
Atmospheric Measurement Techniques | Year: 2014

The difference due to the content of a priori information between a constrained retrieval and the true atmospheric state is usually represented by a diagnostic quantity called smoothing error. In this paper it is shown that, regardless of the usefulness of the smoothing error as a diagnostic tool in its own right, the concept of the smoothing error as a component of the retrieval error budget is questionable because it is not compliant with Gaussian error propagation. The reason for this is that the smoothing error does not represent the expected deviation of the retrieval from the true state but the expected deviation of the retrieval from the atmospheric state sampled on an arbitrary grid, which is itself a smoothed representation of the true state; in other words, to characterize the full loss of information with respect to the true atmosphere, the effect of the representation of the atmospheric state on a finite grid also needs to be considered. The idea of a sufficiently fine sampling of this reference atmospheric state is problematic because atmospheric variability occurs on all scales, implying that there is no limit beyond which the sampling is fine enough. Even the idealization of infinitesimally fine sampling of the reference state does not help, because the smoothing error is applied to quantities which are only defined in a statistical sense, which implies that a finite volume of sufficient spatial extent is needed to meaningfully discuss temperature or concentration. Smoothing differences, however, which play a role when measurements are compared, are still a useful quantity if the covariance matrix involved has been evaluated on the comparison grid rather than resulting from interpolation and if the averaging kernel matrices have been evaluated on a grid fine enough to capture all atmospheric variations that the instruments are sensitive to. This is, under the assumptions stated, because the undefined component of the smoothing error, which is the effect of smoothing implied by the finite grid on which the measurements are compared, cancels out when the difference is calculated. If the effect of a retrieval constraint is to be diagnosed on a grid finer than the native grid of the retrieval by means of the smoothing error, the latter must be evaluated directly on the fine grid, using an ensemble covariance matrix which includes all variability on the fine grid. Ideally, the averaging kernels needed should be calculated directly on the finer grid, but if the grid of the original averaging kernels allows for representation of all the structures the instrument is sensitive to, then their interpolation can be an adequate approximation. © Author(s) 2014.

Jahnke T.,Karlsruhe Institute of Technology
Multiscale Modeling and Simulation | Year: 2011

The chemical master equation plays a fundamental role for the understanding of gene regulatory networks and other discrete stochastic reaction systems. Solving this equation numerically, however, is usually extremely expensive or even impossible due to the huge size of the state space. Thus, the chemical master equation must often be replaced by a reduced model which operates with a considerably smaller number of degrees of freedom but hopefully still provides the essential information about the dynamics of the full system. We prove error bounds for two reduced models which have previously been proposed in the literature. Based on the error analysis, an alternative model reduction approach for the chemical master equation is introduced and discussed, and its advantage is illustrated by numerical examples. © 2011 Society for Industrial and Applied Mathematics.

Rudolph S.,Karlsruhe Institute of Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

This chapter accompanies the foundational lecture on Description Logics (DLs) at the 7th Reasoning Web Summer School in Galway, Ireland, 2011. It introduces basic notions and facts about this family of logics which has significantly gained in importance over the recent years as these logics constitute the formal basis for today's most expressive ontology languages, the OWL (Web Ontology Language) family. We start out from some general remarks and examples demonstrating the modeling capabilities of description logics as well as their relation to first-order predicate logic. Then we begin our formal treatment by introducing the syntax of DL knowledge bases which comes in three parts: RBox, TBox and ABox. Thereafter, we provide the corresponding standard model-theoretic semantics and give a glimpse of the alternative way of defining the semantics via an embedding into first-order logic with equality. We continue with an overview of the naming conventions for DLs before we delve into considerations about different notions of semantic alikeness (concept and knowledge base equivalence as well as emulation). These are crucial for investigating the expressivity of DLs and performing normalization. We move on by reviewing knowledge representation capabilities brought about by different DL features and their combinations as well as some model-theoretic properties associated thereto. Subsequently, we consider typical reasoning tasks occurring in the context of DL knowledge bases. We show how some of these tasks can be reduced to each other, and have a look at different algorithmic approaches to realize automated reasoning in DLs. Finally, we establish connections between DLs and OWL. We show how DL knowledge bases can be expressed in OWL and, conversely, how OWL modeling features can be translated into DLs. In our considerations, we focus on the description logic which underlies the most recent and most expressive yet decidable version of OWL called OWL 2 DL. We concentrate on the logical aspects and omit data types as well as extralogical features from our treatise. Examples and exercises are provided throughout the chapter. © 2011 Springer-Verlag Berlin Heidelberg.

Klinkhamer F.R.,Karlsruhe Institute of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

Adopting the q-theory approach to the cosmological constant problem, a simple field-theoretic model is presented which generates an effective cosmological constant (remnant vacuum energy density) of the observed order of magnitude, Λeff∼(meV)4, if there exist new TeV-scale ultramassive particles with electroweak interactions. The model is simple, in the sense that it involves only a few types of fields and two energy scales, the gravitational energy scale EPlanck∼1015TeV and the electroweak (new-physics) energy scale Eew∼1-10TeV. © 2011 American Physical Society.

Frank R.,Karlsruhe Institute of Technology | Lubatsch A.,University of Bonn
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We present a detailed discussion of scalar wave propagation and light intensity transport in three-dimensional random dielectric media with optical gain. The intrinsic length and time scales of such amplifying systems are studied and comprehensively discussed as well as the threshold characteristics of single- and two-particle propagators. Our semianalytical theory is based on a self-consistent Cooperon resummation, representing the repeated self-interference, and incorporates as well optical gain and absorption, modeled in a semianalytical way by a finite imaginary part of the dielectric function. Energy conservation in terms of a generalized Ward identity is taken into account. © 2011 American Physical Society.

Send R.,Karlsruhe Institute of Technology | Furche F.,University of California at Irvine
Journal of Chemical Physics | Year: 2010

First-order nonadiabatic coupling matrix elements (NACMEs) are key for phenomena such as nonradiative transitions and excited-state decay, yet a consistent and practical first principles treatment has been elusive for molecules with more than a few heavy atoms. Here we present theory, implementation using Gaussian basis sets, and benchmarks of first-order NACMEs between ground and excited states in the framework of time-dependent hybrid density functional theory (TDDFT). A time-dependent response approach to NACMEs which avoids explicit computation of excited-state wave functions is outlined. In contrast to previous approaches, the present treatment produces exact analytical derivative couplings between time-dependent Kohn-Sham (TDKS) determinants in a finite atom-centered basis set. As in analytical gradient theory, derivative molecular orbital coefficients can be eliminated, making the computational cost independent of the number of nuclear degrees of freedom. Our expression reduces to the exact Chernyak-Mukamel formula for first-order NACMEs in the complete basis-set limit, but greatly improves basis-set convergence in finite atom-centered basis sets due to additional Pulay type terms. The Chernyak-Mukamel formula is shown to be equivalent to the Hellmann-Feynman contribution in analytical gradient theory. Our formalism may be implemented in TDDFT analytical excited-state gradient codes with minor modifications. Tests for systems with up to 147 atoms show that evaluation of first-order NACMEs causes total computation times to increase by an insignificant 10% on average. The resolution-of-the-identity approximation for the Coulomb energy (RI-J) reduces the computational cost by an order of magnitude for nonhybrid functionals, while errors are insignificant with standard auxiliary basis sets. We compare the computed NACMEs to full configuration interaction (FCI) in benchmark results for diatomic molecules; hybrid TDDFT and FCI are found to be in agreement for regions of the potential energy curve where the Kohn-Sham ground-state reference is stable and the character of the excitation is properly captured by the present functionals. With these developments, nonadiabatic molecular dynamics simulations of molecular systems in the 100 atoms regime are within reach. © 2010 American Institute of Physics.

Walter V.,Karlsruhe Institute of Technology
Advances in Experimental Medicine and Biology | Year: 2010

This chapter gives an overview of current methods for the isolation of biosurfactant producing microbes. The common screening methods for biosurfactants are presented. Sampling and isolation of bacteria are the basis for screening of biosurfactant producing microbes. Hydrocarbon-contaminated sites are the most promising for the isolation of biosurfactant producing microbes, but many strains have also been isolated from undisturbed sites. In subsequent steps the isolates have to be characterized in order to identify the strains which are interesting for a further investigation. Several techniques have been developed for identifying biosurfactant producing strains. Most of them are directly based on the surface or interfacial activity of the culture supernatant. Apart from that, some screening methods explore the hydrophobicity of the cell surface. This trait also gives an indication on biosurfactant production. In recent years automation and miniaturization have led to the development of high throughput methods for screening. High throughput screening (HTS) for analyzing large amounts of potential candidates or whole culture collections is reflected in the end. However, no new principals have been introduced by HTS methods. © 2010 Landes Bioscience and Springer Science+Business Media.

Grotzbach G.,Karlsruhe Institute of Technology
Nuclear Engineering and Design | Year: 2011

Direct numerical simulations (DNSs) require the resolution of all relevant turbulence scales in space and time, whereas large eddy simulations (LESs) need only to resolve the dominant energy carrying large scales. Important influences from physics and numerics on the small-scale resolution are discussed. Quantitative criteria for turbulent flows are re-evaluated. Experience shows, resolving the microscales is usually by far not achieved in DNS; this is less relevant than the adequate resolution of the anisotropic coherent fine flow structures. These structures depend on the flow type, so that general criteria cannot be given. Resolving the large scales is a serious problem. When the computational domain covers only part of the flow domain, the large-scale resolution is coupled to the artificial boundary conditions for open boundaries. Each measure and criteria have to be carefully considered to ensure that the simulations meet the expectations. Special emphasis is given to liquid metal flows because related nuclear applications are often in the transition range between LES and DNS of the temperature field. A new model is given to predict local turbulent Prandtl numbers for subgrid scale heat flux modeling. It covers the required most important influences: local resolution, a local turbulence parameter, and Reynolds and Prandtl numbers. © 2011 Elsevier B.V. All rights reserved.

Fleck S.C.,Karlsruhe Institute of Technology
Mycotoxin research | Year: 2012

Zearalenone (ZEN) is a highly estrogenic mycotoxin produced by Fusarium species. The adverse effects of ZEN and its reductive metabolite α-zearalenol (α-ZEL) are often compared to those of 17β-estradiol (E2) and estrone (E1). These endogenous steroidal estrogens are associated with an increased risk for cancer, which may be mediated by two mechanisms, i.e. (1) hormonal activity and (2) genotoxic effects after cytochrome P450-catalyzed metabolic activation to catechols. Like E1 and E2, ZEN and α-ZEL exhibit marked estrogenicity and also undergo aromatic hydroxylation to catechol metabolites. The subsequent methylation of catechols by catechol-O-methyltransferase (COMT) is generally considered as a detoxifying pathway. Imbalances between the activation and inactivation reactions can lead to the formation of reactive semiquinones and quinones, which can alkylate DNA or produce reactive oxygen species by redox cycling. In the present study, the genotoxicity of the catechol metabolites of ZEN, α-ZEL, E1 and E2 was determined in a cell-free system by measuring 8-oxo-2'-deoxyguanosine using a LC-DAD-MS(2) method. Each of the individual catechols of ZEN, α-ZEL, E1 and E2 induced oxidative DNA damage in calf thymus DNA. The ranking order of the DNA damaging activity was 15-hydroxy-ZEN/α-ZEL ≈ 2/4-hydroxy-E1/E2 > 13-hydroxy-ZEN/α-ZEL. When hepatic microsomes from different species were incubated with ZEN, the rat had the highest activity for catechol formation, followed by human, mouse, pig and steer. The amount of catechol metabolites correlated directly with the amount of oxidative damage in calf thymus DNA. The ranking order for the rate of methylation by human hepatic COMT was 2-hydroxy-E1/E2 >> 4-hydroxy-E1/E2 >> 13/15-hydroxy-ZEN/α-ZEL. Thus, the catechol metabolites of the mycoestrogen ZEN and its reductive metabolite α-ZEL exhibit a DNA-damaging potential comparable to that of the catechol metabolites of E1 and E2, but are much poorer substrates for inactivation by human COMT.

Riemer M.,Johannes Gutenberg University Mainz | Jones S.C.,Karlsruhe Institute of Technology
Quarterly Journal of the Royal Meteorological Society | Year: 2014

An idealized scenario of extratropical transition (ET) is investigated, in which a tropical cyclone interacts with a high-amplitude, upper-level wave pattern and well-developed surface cyclones. Early during the interaction, the external forcing of the upper-level wave by the ET system is quantified based on a metric for the waviness of the midlatitude flow. Local amplification of the wave pattern is diagnosed, associated prominently with the trough downstream of ET. This amplified trough, however, exhibits pronounced anticyclonic breaking and thus, in contrast to many previous ET studies, it is not clear that the amplification of the upper-level wave propagates into the farther downstream region. Subsequently, the ET system merges with the upstream cyclone. The upstream trough undergoes strong deformation and cyclonic breaking associated with straining due to the cyclonic circulation of the ET system. With the decay of this trough, the ET system weakens considerably and the upper-level wave pattern changes locally to a zonal flow orientation. This zonal flow pattern then extends into the downstream region and promotes the decay of the downstream baroclinic systems. As in previous studies, the evolution of ET exhibits large sensitivity to the initial location of the tropical cyclone. Examining the steering flow's topology, i.e. identifying the stagnation points and the streamlines emanating from these points, helps to identify three different regimes: a no-ET regime and two ET regimes reminiscent of the northwest and northeast patterns, respectively, introduced previously by Harr et al. A stagnation point located on the axis of the upstream trough governs the bifurcation into no-ET and ET regimes. A stagnation point located on the axis of the downstream ridge governs the bifurcation into northwest and northeast patterns. © 2013 Royal Meteorological Society.

Barth A.,Karlsruhe Institute of Technology
Journal of Seismology | Year: 2014

On February 12, 2013 the Democratic People's Republic of Korea (DPRK) carried out an announced nuclear test, which was the third after tests conducted in 2006 and 2009. An important task in discriminating a man-made explosion and a natural tectonic earthquake is the analysis of seismic waveforms. To determine the isotropic and non-isotropic characteristics of the detonation source, I invert long-period seismic data for the full seismic moment tensor to match the observed seismic signals by synthetic waveforms based on a 3D Earth model. Here, I show that the inversion of long-period seismic data of the 2013 test reveals a clear explosive (isotropic) component combined with a significant release of shear energy by the double-couple part of the moment tensor. While the isotropic part of the nuclear test in 2009 was similar to that in 2013, the double-couple part was lower by a factor of 0.55 compared to the explosion in 2013. Moreover, the ratio of the isotropic seismic moments of the 2013 and 2009 nuclear tests is 1.4 ± 0.1 and lower than published estimations of the yield ratio, which indicates the importance of considering the release of shear energy. The determined orientation of the double-couple fault plane is parallel to the dominating geologic fault structures NNE-SSW to NE-SW, but the calculated normal faulting mechanism does not correspond to the general tectonic strike-slip regime. Thus, explanations for the enhanced release of shear energy might be induced dip-slip motion pre-stressed by the previous test or near source damaging effects due to a changed containment of the nuclear explosion. © 2014 Springer Science+Business Media Dordrecht.

Bischoff F.A.,Virginia Polytechnic Institute and State University | Klopper W.,Karlsruhe Institute of Technology
Journal of Chemical Physics | Year: 2010

Second-order perturbation theory using explicitly correlated wave functions has been introduced into a quasirelativistic two-component formalism. The convergence of the correlation energy is as much improved as for the nonrelativistic Hamiltonian, achieving basis-set-limit results in a moderate-size basis set. Equilibrium distances and vibrational frequencies of small molecules of the 6th period of the periodic system of the elements have been calculated, demonstrating the improved behavior of the explicitly correlated wave functions. Taking advantage of density-fitting techniques, the explicitly correlated approach is an economical and appealing alternative to conventional two-component second-order perturbation theory in a large one-particle basis. © 2010 American Institute of Physics.

Jacob C.R.,Karlsruhe Institute of Technology | Reiher M.,ETH Zurich
International Journal of Quantum Chemistry | Year: 2012

The accurate description of open-shell molecules, in particular of transition metal complexes and clusters, is still an important challenge for quantum chemistry. Although density-functional theory (DFT) is widely applied in this area, the sometimes severe limitations of its currently available approximate realizations often preclude its application as a predictive theory. Here, we review the foundations of DFT applied to open-shell systems, both within the nonrelativistic and the relativistic framework. In particular, we provide an in-depth discussion of the exact theory, with a focus on the role of the spin density and possibilities for targeting specific spin states. It turns out that different options exist for setting up Kohn-Sham DFT schemes for open-shell systems, which imply different definitions of the exchange-correlation energy functional and lead to different exact conditions on this functional. Finally, we suggest possible directions for future developments. © 2012 Wiley Periodicals, Inc.

Stein O.,Karlsruhe Institute of Technology
Mathematical Programming | Year: 2012

We present a new smoothing approach for mathematical programs with complementarity constraints, based on the orthogonal projection of a smooth manifold. We study regularity of the lifted feasible set and, since the corresponding optimality conditions are inherently degenerate, introduce a regularization approach involving a novel concept of tilting stability. A correspondence between the C-index in the original problem and the quadratic index in the lifted problem is shown. In particular, a local minimizer of the mathematical program with complementarity constraints may numerically be found by minimization of the lifted, smooth problem. We report preliminary computational experience with the lifting approach. © 2010 Springer and Mathematical Programming Society.

Gruber M.,Karlsruhe Institute of Technology
Nature Materials | Year: 2015

Molecular semiconductors may exhibit antiferromagnetic correlations well below room temperature. Although inorganic antiferromagnetic layers may exchange bias single-molecule magnets, the reciprocal effect of an antiferromagnetic molecular layer magnetically pinning an inorganic ferromagnetic layer through exchange bias has so far not been observed. We report on the magnetic interplay, extending beyond the interface, between a cobalt ferromagnetic layer and a paramagnetic organic manganese phthalocyanine (MnPc) layer. These ferromagnetic/organic interfaces are called spinterfaces because spin polarization arises on them. The robust magnetism of the Co/MnPc spinterface stabilizes antiferromagnetic ordering at room temperature within subsequent MnPc monolayers away from the interface. The inferred magnetic coupling strength is much larger than that found in similar bulk, thin or ultrathin systems. In addition, at lower temperature, the antiferromagnetic MnPc layer induces an exchange bias on the Co film, which is magnetically pinned. These findings create new routes towards designing organic spintronic devices. © 2015 Nature Publishing Group

Grotzbach G.,Karlsruhe Institute of Technology
Nuclear Engineering and Design | Year: 2013

Nuclear heat transfer applications with low-Prandtl number fluids are often in the transition range between conduction and convection dominated regimes. Most flows in reactors involve also anisotropic turbulent fluxes and strong buoyancy influences. The relevance and complexity of the required heat flux modelling is discussed depending on engineering issues. The needed acceptable models range from locally applicable turbulent Prandtl number formulations, over algebraic flux models, to full second order models in RANS as well as in LES, all with special liquid metal extensions. Recommendations are deduced for the promising HYBRID models. The listed remaining challenges show the need for further development of models and instrumentation. © 2013 Elsevier B.V.

Dutschke E.,Fraunhofer Institute for Systems and Innovation Research | Paetz A.-G.,Karlsruhe Institute of Technology
Energy Policy | Year: 2013

Dynamic pricing is being discussed as one method of demand side management (DSM) which could be crucial for integrating more renewable energy sources into the electricity system. At the same time, there have been very few analyses of consumer preferences in this regard: Which type of pricing program are consumers most likely to choose and why? This paper sheds some light on these issues based on two empirical studies from Germany: (1) A questionnaire study including a conjoint analysis-design and (2) A field experiment with test-residents of a smart home laboratory. The results show that consumers are open to dynamic pricing, but prefer simple programs to complex and highly dynamic ones; smart home technologies including demand automation are seen as a prerequisite for DSM. The study provides some indications that consumers might be more willing to accept more dynamic pricing programs if they have the chance to experience in practice how these can be managed in everyday life. At the same time, the individual and societal advantages of such programs are not obvious to consumers. For this reason, any market roll-out will need to be accompanied by convincing communication and information campaigns to ensure that these advantages are perceived. © 2013 Elsevier Ltd.

The use of waste heat from exhaust gas of internal combustion engines in power plants and CHP plants is considered a promising application field for thermoelectrics (TE). Some recent studies have provided important knowledge on the energy efficiency of current and future thermoelectric generators (TEGs). The focus of these studies has been primarily on the precise modelling of power units and their operation, i.e., the quantification of power production by TEGs. One of the studies additionally assessed the costs and the CO2 emissions of fuel combustion, without equipment and fuel supply. Until now, there was no life cycle-related analysis considering TEG and power unit manufacture, environmental impacts beyond climate change and competing technologies for waste heat utilisation. In order to fill this gap, the present study applies the life cycle approach, takes account of a variety of environmental impacts and costs and compares TEGs with the competing steam expander technology. The results show that, under many conditions, TEGs in power units can save energy costs and reduce the environmental burden, i.e., they are eco-efficient. With additional expenditure, energy savings and environmental benefits can be achieved even under disadvantageous conditions. However, in the upper power range the performance of steam expanders in terms of electricity production and eco-efficiency is better. The reduction costs of greenhouse gas emissions and environmental impacts as eco-efficiency indicators show identical patterns. Under reasonable operating conditions, i.e., sufficient capacity utilisation of a TEG (lowest value set in the study on hand: 50%), the impacts from the manufacturing of the TEG play only a small role in the overall assessment. © 2012 Elsevier Ltd.

Lynch I.,University of Birmingham | Weiss C.,Karlsruhe Institute of Technology | Valsami-Jones E.,University of Birmingham | Valsami-Jones E.,Natural History Museum in London
Nano Today | Year: 2014

There is an urgent need to establish a fundamental understanding of the mechanisms of nanomaterial (NM) interaction with living systems and the environment, in order for regulation of NMs to keep pace with their increasing industrial application. Identification of critical properties (physicochemical descriptors) that confer the ability to induce harm in biological systems is crucial, enabling both prediction of impacts from related NMs (via quantitative nanostructure-activity relationships (QNARs) and read-across approaches) and development of strategies to ensure these features are avoided or minimised in NM production in the future ("safety by design"). A number of challenges to successful implementation of such a strategy exist, including: (i) the lack of widely available systematically varied libraries of NMs to enable generation of sufficiently robust datasets for development and validation of QNARs; (ii) the fact that many physicochemical properties of pristine NMs are inter-related and thus cannot be varied systematically in isolation from others (e.g. increasing surface charge may impact on hydrophobicity, or changing the shape of a NM may introduce defects or alter the atomic configuration of the surface); and (iii) the effect of ageing, transformation and biomolecule coating of NMs under environmental or biological conditions. A novel approach to identify interlinked physicochemical properties, and on this basis identify overarching descriptors (axes or principle components) which can be used to correlate with toxicity is proposed. An example of the approach is provided, using three principle components which we suggest can be utilised to fully describe each NM, these being the intrinsic (inherent) properties of the NM, composition (which we propose as a separate parameter) and extrinsic properties (interaction with media, molecular coronas etc.). © 2014 The Authors.

Uhlmann M.,Karlsruhe Institute of Technology | Dusek J.,University of Strasbourg
International Journal of Multiphase Flow | Year: 2014

Detailed data describing the motion of a rigid sphere settling in unperturbed fluid is generated by means of highly-accurate spectral/spectral-element simulations with the purpose of serving as a future benchmark case. A single solid-to-fluid density ratio of 1.5 is chosen, while the value of the Galileo number is varied from 144 to 250 such as to cover the four basic regimes of particle motion (steady vertical, steady oblique, oscillating oblique, chaotic). This corresponds to a range of the particle Reynolds number from 185 to 365. In addition to the particle velocity data, extracts of the fluid velocity field are provided, as well as the pressure distribution on the sphere's surface. Furthermore, the same solid-fluid system is simulated with a particular non-boundary-conforming approach, i.e. the immersed boundary method proposed by Uhlmann (2005a), using various spatial resolutions. It is shown that the current benchmark case allows to adjust the resolution requirements for a given error tolerance in each flow regime. © 2013 Elsevier Ltd.

Peters H.,Karlsruhe Institute of Technology
European Journal of Physics | Year: 2014

The Gibbs paradox of the first kind (GP1) refers to the false increase in entropy which, in statistical mechanics, is calculated from the process of combining two gas systems S1 and S2 consisting of distinguishable particles. Presented in a somewhat modified form, the GP1 manifests as a contradiction to the second law of thermodynamics. Contrary to popular belief, this contradiction affects not only classical but also quantum statistical mechanics. This paper resolves the GP1 by considering two effects. (i) The uncertainty about which particles are located in S1 and which in S2 contributes to the entropies of S1 and S2. (ii) S1 and S2 are correlated by the fact that if a certain particle is located in one system, it cannot be located in the other. As a consequence, the entropy of the total system consisting of S1 and S2 is not the sum of the entropies of S1 and S2. © 2014 IOP Publishing Ltd.

Ferg M.,Karlsruhe Institute of Technology
Briefings in functional genomics | Year: 2014

The precise spatial and temporal control of gene expression is a key process in the development, maintenance and regeneration of the vertebrate body. A substantial proportion of vertebrate genomes encode genes that control the transcription of the genetic information into mRNA. The zebrafish is particularly well suited to investigate gene regulatory networks underlying the control of gene expression during development due to the external development of its transparent embryos and the increasingly sophisticated tools for genetic manipulation available for this model system. We review here recent data on the analysis of cis-regulatory modules, transcriptional regulators and their integration into gene regulatory networks in the zebrafish, using the developing spinal cord as example.

Campanario F.,Karlsruhe Institute of Technology | Sapeta S.,Durham University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

We use the LoopSim and VBFNLO packages to investigate a merged sample of partonic events that is accurate at NLO in QCD simultaneously for the WZ and WZ + jet production processes. In certain regions of phase space such a procedure is expected to account for the dominant part of the NNLO QCD corrections to the WZ production process. For a number of commonly used experimental observables, we find that these corrections are substantial, in the 30-100% range and in some cases their inclusion can reduce scale uncertainties by a factor of two. As in the underlying VBFNLO calculations, we include the leptonic decays of the vector bosons and all off-shell and finite-width effects. © 2012 Elsevier B.V.

Klinkhamer F.R.,Karlsruhe Institute of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

It has been suggested previously that the observed cosmological constant Λ corresponds to the remnant vacuum energy density of dynamical processes taking place at a cosmic age set by the mass scale M∼Eew of ultramassive particles with electroweak interactions. Here, a simple modification of the nondissipative dynamic equations of q-theory is presented, which produces a remnant vacuum energy density (effective cosmological constant) of the correct order of magnitude. Combined with the observed value of Λ, a first estimate of the required value of the energy scale E ew ranges from 3 to 9 TeV, depending on the number of species of ultramassive particles and assuming a dissipative coupling constant of order unity. If correct, this estimate implies the existence of new TeV-scale physics beyond the standard model. © 2010 The American Physical Society.

Brod J.,Karlsruhe Institute of Technology | Brod J.,TU Munich | Gorbahn M.,TU Munich
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We perform a next-to-next-to-leading order QCD analysis of the charm-top-quark contribution ηct to the effective |ΔS|=2 Hamiltonian in the standard model. ηct represents an important part of the short distance contribution to the parameter ∈K. We calculate the three-loop anomalous dimension of the leading operator Q ∼S2, the three-loop mixing of the current-current and penguin operators into Q∼S2, and the corresponding two-loop matching conditions at the electroweak, the bottom-quark, and the charm-quark scale. As our final numerical result we obtain ηct=0.496±0.047, which is roughly 7% larger than the next-to-leading-order (NLO) value ηctNLO=0.457±0.073. This results in a prediction for |∈K|=(1.90±0.26)×10-3, which corresponds to an enhancement of approximately 3% with respect to the value obtained using ηctNLO. © 2010 The American Physical Society.

Klinkhamer F.R.,Karlsruhe Institute of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

Present and future ultra-high-energy-cosmic-ray facilities (e.g., the South and North components of the Pierre Auger Observatory) and TeV-gamma-ray telescope arrays (e.g., HESS and CTA) have the potential to set stringent bounds on the nine Lorentz-violating parameters of nonbirefringent modified Maxwell theory minimally coupled to standard Dirac theory. A concrete example is given how to obtain, in the coming decennia, two-sided bounds on the eight anisotropic parameters at the 10⊃-20 level and an upper (lower) bound on the single isotropic parameter at the +10⊃-20 (-10⊃-16) level. Comparison is made with existing and potential direct bounds from laboratory experiments. © 2010 The American Physical Society.

Thumm M.,Karlsruhe Institute of Technology | Thumm M.,Institute For Hochfrequenztechnik Und Elektronik
IEEE Transactions on Plasma Science | Year: 2014

Progress in the worldwide development of high-power gyrotrons for magnetic confinement fusion plasma applications is presented. Gyrotron oscillators are used for electron cyclotron heating, electron cyclotron current drive, stability control, and plasma diagnostics. After technology breakthroughs in the research on gyrotron components in the 1990s, significant progress has been achieved in the 2000s, in the field of long-pulse and continuous wave (CW) operation for a wide range of frequencies. Currently, the development of 1-MW-class CW gyrotrons for the tokamak ITER (170 GHz), the stellarator Wendelstein 7-X (140 GHz), and the tokamaks DIII-D and JT-60SA (110 GHz) has been very successful in EU, Japan, Russia, and USA. The Japan 170-GHz ITER gyrotron holds the energy world record of 2.88 GJ (0.8 MW at 1-h pulse duration). For this progress in the field of high-power long-pulse gyrotrons, innovations such as the realization of high-efficiency stable oscillation in very high-order cavity modes with low ohmic losses, the use of single-stage depressed collectors for energy recovery (efficiency enhancement and simpler power supplies), highly efficient internal quasi-optical (q.o.) mode converters (low level of internal stray radiation), and synthetic diamond windows have essentially contributed. The total tube efficiencies are around 50% and the purity of the linearly polarized fundamental Gaussian output mode is 97% and higher. Power modulation technologies for stabilization of neoclassical tearing modes have proceeded. Future prospects of advanced high-power fusion gyrotrons are in the areas of two-and three-frequency gyrotrons, fast step-wise frequency tuneability, higher unit power (coaxial cavities), and higher frequencies for more efficient plasma stabilization and noninductive current drive as well as reliability, availability, maintainability and inspectability for next step fusion power stations. The GYCOM step-tuneable 1-MW gyrotron for ASDEX Upgrade employing a broadband travelling-wave-resonator window (with two diamond disks) operates at 105, 117, 127 and 140 GHz. The EU 170 GHz coaxial-cavity gyrotron prototype achieved in millisecond pulses the power of 2.1 MW at 46% efficiency and 96% Gaussian mode purity. A new power record of second harmonic oscillation has been achieved in the subterahertz band (83 kW/389 GHz/3 ms) in Japan for application to collective Thomson scattering diagnostics. A fundamental frequency 670-GHz gyrotron with pulsed magnet generated 210 kW in 20-30-μs pulses at 20% efficiency (collaboration of institutions in Russia and USA). © 1973-2012 IEEE.

Igitkhanov Y.L.,Karlsruhe Institute of Technology
Contributions to Plasma Physics | Year: 2014

A substantial portion of poloidal magnetic energy stored in the RE beam could dissipate in the first wall (FW) armor due to ohmic dissipation of inductive current. Relatively small part of magnetic energy can also be converted into heat during a direct impact of the RE beam on the FW due to the ohmic dissipation of a return current, induced by penetration of the RE beam into a metal in the skin time scale. The observed increase of temperature at a spot on the JET dump plate upon increasing the RE current can be explained by assuming that 50 % of the RE energy, predominantly magnetic energy, is converted into heat. Calculations of the RE stopping power (SP) onto the ITER FW Be bulk armor predict strong erosion. While the threshold energy for beryllium melting is about 5 MJ/m2, the RE heat deposition is expected to be almost twice as large. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diaz J.S.,Karlsruhe Institute of Technology
Advances in High Energy Physics | Year: 2014

Low-energy experiments studying single beta decay can serve as sensitive probes of Lorentz invariance that can complement interferometric searches for deviations from this spacetime symmetry. Experimental signatures of a dimension-three operator for Lorentz violation which are unobservable in neutrino oscillations are described for the decay of polarized and unpolarized neutrons as well as for measurements of the spectral endpoint in beta decay. © 2014 Jorge S. Díaz.

Klinkhamer F.R.,Karlsruhe Institute of Technology
Acta Physica Polonica B | Year: 2014

With a prescribed Coulomb-type energy-momentum tensor, an exact solution of the Einstein field equations over a nonsimply-connected manifold is presented. This spherically symmetric solution has neither curvature singularities nor closed timelike curves. It can be considered to be a regularization of the singular Reissner - Nordström solution over a simplyconnected manifold.

Printz M.,Karlsruhe Institute of Technology
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2014

The upgrade of the LHC machine to deliver a significantly higher luminosity of about 5×1034cm-2s-1 is planned to be operational after 2022. This will simultaneously increase the radiation dose for the inner detector systems, requiring new radiation hard sensor materials for the CMS Tracker. To identify the appropriate materials which are able to withstand the radiation environment in the middle to outer layers of the CMS Tracker during the full lifetime of the high luminosity LHC, a large irradiation and measurement campaign has been conducted. Several test structures and sensors have been designed and manufactured on 18 different combinations of wafer materials, thicknesses and production technologies. The structures have been electrically characterised before and after irradiation with different fluences of neutrons and protons. This paper reports the final results on strip sensor performance considering the comparison of p-in-n technology with n-in-p type. Outcomes from signal and noise measurements before and after annealing depending on the radiation dose are discussed and the final recommendation of the CMS Tracker Collaboration for the strip sensor polarity for the Phase II Upgrade is presented. © 2014 Elsevier Ltd. All rights reserved.

Krotzsch M.,Karlsruhe Institute of Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

We develop inferencing methods for a DL that subsumes the main features of the W3C recommendation OWL EL -, and present a framework for studying materialisation calculi based on datalog. The latter is used to investigate the resource requirements for inferencing, and we can show that certain feature combinations must lead to increased space upper bounds in any materialisation calculus, suggesting that efficient implementations are easier to obtain for suitably chosen fragments of 2010 Springer-Verlag.

Hauser R.,Karlsruhe Institute of Technology
Journal of bacteriology | Year: 2011

Mass spectrometry analysis of Streptococcus pneumoniae bacteriophage Cp-1 identified a total of 12 proteins, and proteome-wide yeast two-hybrid screens revealed 17 binary interactions mainly among these structural proteins. On the basis of the resulting linkage map, we suggest an improved structural model of the Cp-1 virion.

Denkevits A.,Karlsruhe Institute of Technology
Fusion Engineering and Design | Year: 2010

The work is aimed at supporting inert-gas dilution method proposed to mitigate hydrogen/dust explosion hazard in ITER in case of severe accidents. A standard method of 20-l sphere is used to study the effect of nitrogen dilution on the explosion behavior of 0.5-μm tungsten dust dispersed in hydrogen-containing air atmospheres. The oxygen content varied from normal 21 to 10 vol.%. The hydrogen concentration was varied from 7 to 18 vol.%; the tungsten dust cloud density of 2 kg/m3 was chosen to test as the optimal, i.e. the most dangerous dust concentration. The tested mixtures were formed in a spherical combustion chamber of 20-l volume at normal initial conditions and ignited at its center by a weak electric spark. In general, the tested dust/hydrogen mixtures explode more dangerously than hydrogen alone: they can generate higher explosion overpressures and explode faster than the corresponding hydrogen/air mixtures without dust. For all the tested mixtures the nitrogen dilution reduces both the explosion overpressure and pressure rise rate; however, its influence is more pronounced on how fast combined explosions proceed. In case of 7 vol.% H2, the explosion overpressure decreases from 4.5 to 3.5 bar at O2 decrease from 21 to 10 vol.%, while the pressure rise rate drops from 400 to 60bar/s. In case of 18 vol.% of H2, the corresponding values are 6.2-2.6 bar explosion overpressure and 1370-170 bar/s pressure rise rate. An extrapolation of the obtained results to lower oxygen concentrations gives the value of limiting oxygen concentration, at which the combined explosions are to be suppressed, about 8-9 vol.%. © 2010 Elsevier B.V. All rights reserved.

Schulz H.,Karlsruhe Institute of Technology
Catalysis Today | Year: 2011

Selectivity in petroleum chemistry generally means multi-compound product compositions, distributed over a wide range from, e.g. hydrocarbon gases up to vapors of high boiling substances - thus providing analytical problems. Temporal resolution is required for investigating unsteady regimes of reaction, as pertinent during self-organization of catalytic processes or phenomena of catalyst deactivation. It is also of interest in temperature programmed operation as for catalyst regeneration, pyrolysis of organic materials as oil shale and biomass or TPD of pollutants recovered on adsorbents. For temporal resolution instant ampoule sampling has been developed. Ampoule samples are taken from the (hot) gaseous product flow in pre-evacuated glass ampoules in less than 1 s and stored without compositional changes for later GC-analysis. High resolution gas chromatography has been developed, starting at -80 °C for the separation of light gases and ending at, e.g. 250 °C for separating high boiling compounds (e.g. vapors of hydrocarbons C20). In the article, initial selectivity changes in Fischer-Tropsch synthesis (referring to chain growth, chain branching and olefin reactions, as caused by self-organization of the FT-regime) and also thermal regeneration of a HZSM5 catalyst used for methanol conversion at low temperature (referring to reactivation by de-alkylation of bulky benzene derivates) are being presented. © 2011 Elsevier B.V. All rights reserved.

Alavirad H.,Karlsruhe Institute of Technology | Sheykhi A.,Shiraz University | Sheykhi A.,Research Institute for Astronomy and Astrophysics of Maragha RIAAM
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

By using a Markov Chain Monte Carlo simulation, we investigate cosmological constraints on the ghost dark energy (GDE) model in the framework of the Brans-Dicke (BD) theory. A combination of the latest observational data of the cosmic microwave background radiation data from seven-year WMAP, the baryon acoustic oscillation data form the SDSS, the supernovae type Ia data from the Union2 and the X-ray gas mass fraction data from the Chandra X-ray observations of the largest relaxed galaxy clusters are used to perform constraints on GDE in the BD cosmology. In this paper, we consider both flat and non-flat universes together with interaction between dark matter and dark energy. The main cosmological parameters are obtained as: Ωbh2=0.0223-0.0013+0.0016, Ωch2=0.1149-0.0104+0.0088 and Ωk=0.0005-0.0073+0.0025. In addition, the Brans-Dicke parameter ω is estimated as 1/ω ≃ 0.002. © 2014 The Authors.

Crivellin A.,Karlsruhe Institute of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We study the effect of a right-handed coupling of quarks to the W-boson on the measurements of |Vub| and |Vcb|. It is shown that such a coupling can remove the discrepancies between the determinations of |Vub| from B→πℓν , B+→τ+ν, and B→Xuℓν. Further the measurements of |Vcb| from B→D*ℓν, B→Dℓν and inclusive B→Xcℓν decays can be brought into better agreement. We demonstrate that a right-handed coupling can be generated within the minimal supersymmetric standard model by a finite gluino-squark loop. The effect involves the parameters δ23uRL and δ13uRL of the squark mass matrices, which are poorly constrained from other processes. On the other hand, all gluino-squark corrections to the regular left-handed coupling of the W-boson are found to be too small to be relevant. © 2010 The American Physical Society.

Thumm M.K.A.,Karlsruhe Institute of Technology
Journal of Infrared, Millimeter, and Terahertz Waves | Year: 2011

Gyrotrons with output powers of several 100 kW are mainly used as high-power millimeter (mm)-wave sources for electron cyclotron resonance heating (ECRH), electron cyclotron current drive (ECCD), stability control and diagnostics of magnetically confined plasmas for generation of energy by controlled thermonuclear fusion. Other applications include ECR ion sources, materials processing and plasma chemistry, high-resolution Doppler radar, radar ranging and imaging in atmospheric and planetary science, active denial systems, as well as detection of concealed radioactive materials. The present review summarizes the status of recent developments on high-power gyrotrons and introduces this Special Issue on Gyrotrons. © 2010 Springer Science+Business Media, LLC.

Hartwig A.,Karlsruhe Institute of Technology
Metal Ions in Life Sciences | Year: 2013

Cadmium is an established human and animal carcinogen. Most evidence is available for elevated risk for lung cancer after occupational exposure; however, associations between cadmium exposure and tumors at other locations including kidney, breast, and prostate may be relevant as well. Furthermore, enhanced cancer risk may not be restricted to comparatively high occupational exposure, but may also occur via environmental exposure, for example in areas in close proximity to zinc smelters. The underlying mechanisms are still a matter of manifold research activities. While direct interactions with DNA appear to be of minor importance, elevated levels of reactive oxygen species (ROS) have been detected in diverse experimental systems, presumably due to an inactivation of detoxifying enzymes. Also, the interference with proteins involved in the cellular response to DNA damage, the deregulation of cell growth as well as resistance to apoptosis appears to be involved in cadmium-induced carcinogenicity. Within this context, cadmium has been shown to disturb nucleotide excision repair, base excision repair, and mismatch repair. Particularly sensitive targets appear to be proteins with zinc-binding structures, present in DNA repair proteins such as XPA, PARP-1 as well as in the tumor suppressor protein p53. Whether or not these interactions are due to displacement of zinc or due to reactions with thiol groups involved in zinc complex-ation or in other critical positions under realistic exposure conditions remains to be elucidated. Further potential mechanisms relate to the interference with cellular redox regulation, either by enhanced generation of ROS or by reaction with thiol groups involved in the regulation of signaling pathways. Particularly the combination of these multiple mechanisms may give rise to a high degree of genomic instability evident in cadmium-adapted cells, relevant not only for tumor initiation, but also for later steps in tumor development. © Springer Science+Business Media Dordrecht 2013.

Pastewka L.,Fraunhofer Institute for Mechanics of Materials | Moser S.,Fraunhofer Institute for Mechanics of Materials | Gumbsch P.,Fraunhofer Institute for Mechanics of Materials | Gumbsch P.,Karlsruhe Institute of Technology | And 2 more authors.
Nature Materials | Year: 2011

Diamond is the hardest material on Earth. Nevertheless, polishing diamond is possible with a process that has remained unaltered for centuries and is still used for jewellery and coatings: the diamond is pressed against a rotating disc with embedded diamond grit. When polishing polycrystalline diamond, surface topographies become non-uniform because wear rates depend on crystal orientations. This anisotropy is not fully understood and impedes diamondĝ€™s widespread use in applications that require planar polycrystalline films, ranging from cutting tools to confinement fusion. Here, we use molecular dynamics to show that polished diamond undergoes an sp 3 -sp 2 order-disorder transition resulting in an amorphous adlayer with a growth rate that strongly depends on surface orientation and sliding direction, in excellent correlation with experimental wear rates. This anisotropy originates in mechanically steered dissociation of individual crystal bonds. Similarly to other planarization processes, the diamond surface is chemically activated by mechanical means. Final removal of the amorphous interlayer proceeds either mechanically or through etching by ambient oxygen. © 2011 Macmillan Publishers Limited. All rights reserved.

Hofheinz D.,Karlsruhe Institute of Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

We put forward a generalization of lossy trapdoor functions (LTFs). Namely, all-but-many lossy trapdoor functions (ABM-LTFs) are LTFs that are parametrized with tags. Each tag can either be injective or lossy, which leads to an invertible or a lossy function. The interesting property of ABM-LTFs is that it is possible to generate an arbitrary number of lossy tags by means of a special trapdoor, while it is not feasible to produce lossy tags without this trapdoor. Our definition and construction can be seen as generalizations of all-but-one LTFs (due to Peikert and Waters) and all-but-N LTFs (due to Hemenway et al.). However, to achieve ABM-LTFs (and thus a number of lossy tags which is not bounded by any polynomial), we have to employ some new tricks. Concretely, we give two constructions that use "disguised" variants of the Waters, resp. Boneh-Boyen signature schemes to make the generation of lossy tags hard without trapdoor. In a nutshell, lossy tags simply correspond to valid signatures. At the same time, tags are disguised (i.e., suitably blinded) to keep lossy tags indistinguishable from injective tags. ABM-LTFs are useful in settings in which there are a polynomial number of adversarial challenges (e.g., challenge ciphertexts). Specifically, building on work by Hemenway et al., we show that ABM-LTFs can be used to achieve selective opening security against chosen-ciphertext attacks. One of our ABM-LTF constructions thus yields the first SO-CCA secure encryption scheme with compact ciphertexts ( group elements) whose efficiency does not depend on the number of challenges. Our second ABM-LTF construction yields an IND-CCA (and in fact SO-CCA) secure encryption scheme whose security reduction is independent of the number of challenges and decryption queries. © 2012 International Association for Cryptologic Research.

Huege T.,Karlsruhe Institute of Technology
Brazilian Journal of Physics | Year: 2014

Nearly 50 years ago, the first radio signals from cosmic ray air showers were detected. After many successful studies, however, research ceased not even 10 years later. Only a decade ago, the field was revived with the application of powerful digital signal processing techniques. Since then, the detection technique has matured, and we are now in a phase of transition from small-scale experiments accessing energies below 1018 eV to experiments with a reach for energies beyond 1019 eV. We have demonstrated that air shower radio signals carry information on both the energy and the mass of the primary particle, and current experiments are in the process of quantifying the precision with which this information can be accessed. All of this rests on solid understanding of the radio emission processes which can be interpreted as a coherent superposition of geomagnetic emission, Askaryan charge-excess radiation, and Cherenkov-like coherence effects arising in the density gradient of the atmosphere. In this article, I highlight the “state of the art” of radio detection of cosmic rays and briefly discuss its perspectives for the next few years. © 2014, Sociedade Brasileira de Física.

Schilling F.-P.,Karlsruhe Institute of Technology
International Journal of Modern Physics A | Year: 2012

This review summarizes the highlights in the area of top quark physics obtained with the two general purpose detectors ATLAS and CMS during the first two years of operation of the Large Hadron Collider (LHC). It covers the 2010 and 2011 data taking periods, where the LHC provided pp collisions at a center-of-mass energy of √s = 7 TeV. Measurements are presented of the total and differential top quark pair production cross-section in many different channels, the top quark mass and various other properties of the top quark and its interactions, for instance the charge asymmetry. Measurements of single top quark production and various searches for new physics involving top quarks are also discussed. The already very precise experimental data are in good agreement with the standard model (SM). © 2012 World Scientific Publishing Company.

Kampert K.-H.,University of Wuppertal | Unger M.,Karlsruhe Institute of Technology
Astroparticle Physics | Year: 2012

In this paper we review air shower data related to the mass composition of cosmic rays above 10 15 eV. After explaining the basic relations between air shower observables and the primary mass and energy of cosmic rays, we present different approaches and results of composition studies with surface detectors. Furthermore, we discuss measurements of the longitudinal development of air showers from non-imaging Cherenkov detectors and fluorescence telescopes. The interpretation of these experimental results in terms of primary mass is highly susceptible to the theoretical uncertainties of hadronic interactions in air showers. We nevertheless attempt to calculate the logarithmic mass from the data using different hadronic interaction models and to study its energy dependence from 10 15 eV to 10 20 eV. © 2012 Elsevier B.V. All rights reserved.

Hartmann F.,Karlsruhe Institute of Technology
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2012

Since the fifties, semiconductors have been used as energy spectrometers, mainly in unsegmented ways. With the planar technique of processing silicon sensors in unprecedented precession, strip-like segmentation has allowed precise tracking and even vertexing, culminating in the early eighties with NA11 in the tagging of heavy flavor quarks - here the c-quark. With the later miniaturization of electronics, dense detector application was made possible, and large-scale systems were established in the heart of all LEP detectors, permitting vertexing in barrel-like detectors. At the time of LEP and the TEVATRON, tasks were still bifurcated. Small silicon detectors (up to three layers) did the vertexing and further out, gaseous detectors (e.g., drift chambers or time-projection chambers) with larger lever arms did the tracking. In RUN II of the CDF detector, larger silicon tracking devices, still complemented by a huge drift chamber, began to use a stand-alone tracking. At the LHC, ATLAS and CMS bifurcate in a slightly different way. Silicon pixel detectors are responsible for the vertexing, and large volume silicon strip detectors (up to 14 layers) are the main tracking devices. Silicon tracking systems are a fundamental part of modern multipurpose high-energy physics experiments. Despite the vertexing and thus the heavy quark tagging, silicon tracking detectors in combination with a strong B-field deliver the most accurate momentum measurement, and for a large range, also the best energy measurement. In this paper, the functionality of pixel and strip sensors will be introduced, and historical examples will be given to highlight the different implementations of the past 30 years. © 2011 Elsevier B.V. All rights reserved.

Eber R.,Karlsruhe Institute of Technology
Journal of Instrumentation | Year: 2014

Within the CERN RD50 Collaboration, a massive R&D programme is underway across experimental boundaries to develop silicon sensors with sufficient radiation tolerance. One research topic is to gain a deeper understanding of the connection between the macroscopic sensor properties such as radiation-induced increase of leakage current, doping concentration and trapping, and the microscopic properties at the defect level. RD50 also studies sensors made from p-type silicon bulk, which have a superior radiation hardness as they collect electrons instead of holes, exploiting the lower trapping probability of the electrons due to their higher mobility. Simulations have become important to predict the performance of silicon sensors at high fluences. They can be a useful tool to explore the large parameter space of strip sensor geometries and help to explain the charge multiplication effect occuring in sensors at high radiation levels. Charge multiplication plays an important role in sensors irradiated to high fluences and is investigated in RD50. Several studies are ongoing to exploit the effect for future silicon sensors. The latest results of the microscopic studies, the simulation activities, the performance of heavily irradiated strip sensors and the investigations on charge multiplication are presented.© CERN 2014 for the benefit of the RD50 collaboration..

Maier A.,University of Turin | Marquard P.,Karlsruhe Institute of Technology
Nuclear Physics B | Year: 2012

We calculate three-loop corrections to correlation functions of heavy-quark currents in the low- and high-energy regions. We present 30 coefficients both in the low-energy and the high-energy expansion of the scalar and the vector correlator with non-diagonal flavour structure. In addition we compute 30 coefficients in the high-energy expansion of the diagonal vector, axial-vector, scalar and pseudo-scalar correlators. Possible applications of our new results are improvements of lattice-based quark-mass determinations and the approximate reconstruction of the full momentum dependence of the correlators. © 2012 Elsevier B.V.

Jansen L.,University of Munster | Holscher H.,Karlsruhe Institute of Technology | Fuchs H.,University of Munster | Schirmeisen A.,University of Munster
Physical Review Letters | Year: 2010

We report experiments of atomic stick-slip friction on graphite as an explicit function of surface temperature between 100 and 300 K under ultrahigh vacuum conditions. A statistical analysis of the individual stick-slip events as a function of the velocity reveals an agreement with the thermally activated Prandtl-Tomlinson model at all temperatures. Taking into account an explicit temperature-dependence of the attempt frequency all data points collapse onto one single master curve. © 2010 The American Physical Society.

Klinkhamer F.R.,Karlsruhe Institute of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

It has been suggested recently to study the dynamics of a gravitating gluon condensate q in the context of a spatially flat Friedmann-Robertson-Walker universe. The expansion of the Universe (or, more generally, the presence of a nonvanishing Ricci curvature scalar R) perturbs the gluon condensate and may induce a nonanalytic term h̃(R,q) in the effective gravitational action. The aim of this article is to explore the cosmological implications of a particular nonanalytic term h̃ η|R|1/2|q| 3/4. With a quadratic approximation of the gravitating gluon-condensate vacuum energy density ρV(q) near the equilibrium value q0 and a small coupling constant η of the modified-gravity term h̃, an "accelerating universe" is obtained which resembles the present Universe, both qualitatively and quantitatively. The unknown component X of this model universe (here, primarily due to modified-gravity effects) has an effective equation-of-state parameter w̄X which is found to evolve toward the value -1 from above. © 2010 The American Physical Society.

Smirnov A.V.,Moscow State University | Tentyukov M.,Karlsruhe Institute of Technology
Nuclear Physics B | Year: 2010

We present numerical results which are needed to evaluate all non-trivial master integrals for four-loop massless propagators, confirming the recent analytic results of Baikov and Chetyrkin (2010) [1] and evaluating an extra order in e{open} expansion for each master integral. © 2010 Elsevier B.V.

Copeland E.J.,University of Nottingham | Rahmede C.,Karlsruhe Institute of Technology | Saltas I.D.,University of Nottingham
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We revisit Starobinsky inflation in a quantum gravitational context, by means of the exact renormalization group (RG). We calculate the nonperturbative beta functions for Newton's "constant" G and the dimensionless R2 coupling, and show that there exists an attractive UV fixed point where the latter one vanishes but not the former one, and we provide the corresponding beta functions. The smallness of the R2 coupling, required for agreement with inflationary observables, is naturally ensured by its vanishing at the UV fixed point, ensuring the smallness of the primordial fluctuations, as well as providing a theoretical motivation for the initial conditions needed for successful inflation in this context. We discuss the corresponding RG dynamics, showing both how inflationary and classical observations define the renormalization conditions for the couplings, and also how the UV regime is connected with lower energies along the RG flow. Finally, we discuss the consistency of our results when higher-order curvature corrections are included, and show that they are robust to the inclusion of R3 corrections. © 2015 American Physical Society.

Konyukhov A.,Karlsruhe Institute of Technology
International Journal for Numerical Methods in Engineering | Year: 2016

The main feature of the geometrically exact theory of contact is that all objects, which are necessary for computation, weak form and residual, linearized weak form, and tangent matrices are given in a covariant closed form in the local coordinate system corresponding to the geometry of contact pairs. This allows easily to construct computational algorithms for the normal and tangential follower forces as an inverse contact algorithm. In this case, following the definition of the follower forces as given and not changing in the local coordinate system, we have to modify all objects for the contact taking into account the definition of follower forces instead of constitutive relationships for the contact interfaces. The main feature is that the tangent matrices for both normal and tangential part being split into the rotational and the curvature parts are symmetric for any order of approximation. The following numerical examples are selected in the current article to illustr