TY - JOUR A1 - Khelifi, N. A1 - Sarnthein, M. A1 - Naafs, B. D. A. T1 - Technical note: Late Pliocene age control and composite depths at ODP Site 982, revisited JF - CLIMATE OF THE PAST N2 - Ocean Drilling Program (ODP) Site 982 provided a key sediment section at Rockall Plateau for reconstructing northeast Atlantic paleoceanography and monitoring benthic delta O-18 stratigraphy over the late Pliocene to Quaternary onset of major Northern Hemisphere glaciation. A renewed hole-specific inspection of magnetostratigraphic reversals and the addition of epibenthic delta O-18 records for short Pliocene sections in holes 982A, B, and C, crossing core breaks in the delta O-18 record published for Hole 982B, now imply a major revision of composite core depths. After tuning to the orbitally tuned reference record LR04, the new composite delta O-18 record results in a hiatus, where the Kaena magnetic subchron might have been lost, and in a significant age reduction for all proxy records by 130 to 20 ky over the time span 3.2-2.7 million years ago (Ma). Our study demonstrates the general significance of reliable composite-depth scales and delta O-18 stratigraphies in ODP sediment records for generating ocean-wide correlations in paleoceanography. The new concept of age control makes the late Pliocene trends in SST (sea surface temperature) and atmospheric pCO(2) at Site 982 more consistent with various paleoclimate trends published from elsewhere in the North Atlantic. Y1 - 2012 U6 - https://doi.org/10.5194/cp-8-79-2012 SN - 1814-9324 VL - 8 IS - 1 SP - 79 EP - 87 PB - COPERNICUS GESELLSCHAFT MBH CY - GOTTINGEN ER - TY - JOUR A1 - Knoops, Femke A1 - Erbil, Fethiye A1 - Ertürk, Mustafa T1 - Teaching patterns and trends JF - Potsdamer geographische Praxis N2 - 1. Outline 2. Definition 3. Why is it important (or not) to teach about patterns and trends? What are the strengths and weaknesses of teaching patterns and trends? 4. How were patterns and trends offered in the original assignments? 5. What did the student teacher change in practice? How did it go? 6. Suggestions for improving patterns and trends KW - Europäische Werteerziehung KW - Familie KW - Lehrevaluation KW - Studierendenaustausch KW - Unterrichtseinheiten KW - Curriculum Framework KW - European values education KW - Family KW - lesson evaluation KW - student exchange KW - teaching units KW - curriculum framework Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-65845 SN - 2194-1599 SN - 2194-1602 IS - 1 SP - 75 EP - 79 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Uhlenwinkel, Anke A1 - Krause, Uwe A1 - Halman, Loek A1 - Rokven, Josja A1 - Sieben, Inge A1 - Pažický, Michal A1 - Blahušiaková, Andrea A1 - Röper-Kühnemann, Christian A1 - Staufenbiel, Christoph A1 - Vozárová, Hana A1 - Hintze, Katarina A1 - Ivaška, Michal A1 - Kallenbach, René A1 - Majer, Zdenko A1 - Röll, Juliane A1 - Pisarčík, Stanislav A1 - Weiser, Ines A1 - Seeger, Anett A1 - Strehmann, Anja A1 - Chovanová, Katarina A1 - Gembický, Kamil A1 - Nern, Luise A1 - Cornelissen, Sebastiaan A1 - Turgut, Pelin A1 - Knoops, Femke A1 - Erbil, Fethiye A1 - Ertürk, Mustafa A1 - Akpinar, Seda A1 - Maas, Desiree A1 - Rooth, Anneke A1 - Azar, Elif Zeynep A1 - Erdönmez, Çağlayan A1 - Verscheijden, Desirée A1 - Altuntas, Kezban A1 - Akçay, Pinar A1 - Kools, Suzanne A1 - Schnabel, Richard A1 - van den Beemt, Martijn A1 - Çinkaya, Muhammed A1 - Erdem, Didem Tuğçe A1 - Janssen, Robert ED - Uhlenwinkel, Anke T1 - Teaching about the religious values of Europeans : critical reflections from the second student exchange of the EVE-project N2 - The European Values Education (EVE) project is a large-scale, cross-national, and longitudinal survey research programme on basic human values. The main topic of its second stage was religion in Europe. Student teachers of several universities in Europe worked together in multicultural exchange groups. Their results are presented in this issue. T3 - Potsdamer Geographische Praxis - 1 KW - Europäische Werteerziehung KW - Religion KW - Lehrevaluation KW - Studierendenaustausch KW - Unterrichtseinheiten KW - Curriculum Framework KW - European values education KW - religion KW - lesson evaluation KW - student exchange KW - teaching units KW - curriculum framework Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-59010 SN - 978-3-86956-175-2 ER - TY - JOUR A1 - Wildish, J. A1 - Pavesi, Laura A1 - Ketmaier, Valerio T1 - Talitrid amphipods (Crustacea: Amphipoda: Talitridae) and the driftwood ecological niche a morphological and molecular study JF - Journal of natural history : an international journal of systematics, interactive biology and biodiversity. - London : Taylor & Francis   1.1967 - N2 - Coastal regions of the North East Atlantic and Mediterranean Seas have four known species of driftwood talitrids. Records are extremely scanty, often limited to the type locality and dating to 1950. We were able to study three of them, all belonging to the genus Macarorchestia, using fresh and archived samples including type material. Allometric and molecular analyses support: (1) a close relationship among all the three classically defined Macarorchestia species, (2) Macarorchestia was well separated from non-driftwood taxa, and (3) a putative new driftwood talitrid discovered during this study was not closely related to Macarorchestia. Genetic divergence between the new species and Macarorchestia remyi is as high as the average distance among a number of talitrid species included in the study for comparison. A key is provided to identify all three of the presently known species of Macarorchestia, using morphological characters employed in the allometric study. KW - Macarorchestia remyi KW - Macarorchestia roffensis KW - Macarorchestia martini KW - Driftwood habitat KW - COI-DNA barcoding KW - allometry Y1 - 2012 U6 - https://doi.org/10.1080/00222933.2012.717971 SN - 0022-2933 VL - 46 IS - 43-44 SP - 2677 EP - 2700 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Herzog, Marc A1 - Schick, Daniel A1 - Leitenberger, Wolfram A1 - Shayduk, Roman A1 - van der Veen, Renske M. A1 - Milne, Christopher J. A1 - Johnson, Steven Lee A1 - Vrejoiu, Ionela A1 - Bargheer, Matias T1 - Tailoring interference and nonlinear manipulation of femtosecond x-rays JF - New journal of physics : the open-access journal for physics N2 - We present ultrafast x-ray diffraction (UXRD) experiments on different photoexcited oxide superlattices. All data are successfully simulated by dynamical x-ray diffraction calculations based on a microscopic model, that accounts for the linear response of phonons to the excitation laser pulse. Some Bragg reflections display a highly nonlinear strain dependence. The origin of linear and two distinct nonlinear response phenomena is discussed in a conceptually simpler model using the interference of envelope functions that describe the diffraction efficiency of the average constituent nanolayers. The combination of both models facilitates rapid and accurate simulations of UXRD experiments. Y1 - 2012 U6 - https://doi.org/10.1088/1367-2630/14/1/013004 SN - 1367-2630 VL - 14 IS - 1 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Andres, Dorothee A1 - Roske, Yvette A1 - Doering, Carolin A1 - Heinemann, Udo A1 - Seckler, Robert A1 - Barbirz, Stefanie T1 - Tail morphology controls DNA release in two Salmonella phages with one lipopolysaccharide receptor recognition system JF - Molecular microbiology N2 - Bacteriophages use specific tail proteins to recognize host cells. It is still not understood to molecular detail how the signal is transmitted over the tail to initiate infection. We have analysed in vitro DNA ejection in long-tailed siphovirus 9NA and short-tailed podovirus P22 upon incubation with Salmonella typhimurium lipopolysaccharide (LPS). We showed for the first time that LPS alone was sufficient to elicit DNA release from a siphovirus in vitro. Crystal structure analysis revealed that both phages use similar tailspike proteins for LPS recognition. Tailspike proteins hydrolyse LPS O antigen to position the phage on the cell surface. Thus we were able to compare in vitro DNA ejection processes from two phages with different morphologies with the same receptor under identical experimental conditions. Siphovirus 9NA ejected its DNA about 30 times faster than podovirus P22. DNA ejection is under control of the conformational opening of the particle and has a similar activation barrier in 9NA and P22. Our data suggest that tail morphology influences the efficiencies of particle opening given an identical initial receptor interaction event. Y1 - 2012 U6 - https://doi.org/10.1111/j.1365-2958.2012.08006.x SN - 0950-382X VL - 83 IS - 6 SP - 1244 EP - 1253 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Neuvonen, Kari A1 - Neuvonen, Helmi A1 - Koch, Andreas A1 - Kleinpeter, Erich T1 - Taft equation in the light of NBO computations introduction of a novel polar computational substituent constant scale sigma(q)* for alkyl groups JF - Computational and theoretical chemistry N2 - The validity of the Taft equation: log(k(R)/k(CH3)) = rho*sigma* + delta E-S was studied with the aid of NBO computational results concerning cyclohexyl esters RCOOC6H11 [R = Methyl, Ethyl, n-Propyl, Isopropyl, n-Butyl, Isobutyl, sec-Butyl, tert-Butyl, Neopentyl, CH(CH2CH3)(2), CH(CH3)C(CH3)(3), C(CH3)(2)CH2CH3, C(CH3)(2)C(CH3)(3), CH(CH3)(Np), CH(iPr)(tBu), C(Me)(Et)(iPr), C(Et)(2)(tBu) or C(Et)(iPr)(tBu)]. It was proved that the sigma*(alkyl) value is a composite substitutent constant including the polar and steric contributions. A novel computational sigma(q)* substituent constant scale is presented based on the NBO atomic charges of the alpha-carbon and the computational total steric exchange energies E(ster) of the cyclohexyl esters specified above. The method used offers a useful way to calculate sigma*(alkyl) values for alkyl groups for which experimental Taft's polar sigma* parameters are not available. KW - NBO analysis KW - Taft equation KW - Polar substituent constant KW - Steric effect Y1 - 2012 U6 - https://doi.org/10.1016/j.comptc.2011.11.044 SN - 2210-271X VL - 981 IS - 2 SP - 52 EP - 58 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Neuvonen, Kari A1 - Neuvonen, Helmi A1 - Koch, Andreas T1 - Taft equation in the light of NBO computations : Introduction of a novel polar computational substituent constant scale for alkyl groups Y1 - 2012 SN - 2210-271X ER - TY - THES A1 - Irgang, Susann T1 - Systemic characterization of the TOR-signaling pathway in chlamydomonas reinhardtii Y1 - 2012 CY - Potsdam ER - TY - JOUR A1 - Heinz, S. A1 - Jung, I. A1 - Stegmann, Christian T1 - Systematic studies of the Richardson-Lucy deconvolution algorithm applied to VHE gamma data JF - ASTROPARTICLE PHYSICS N2 - The Richardson-Lucy deconvolution algorithm was applied to astronomical images in the very high-energy regime with photon energies above 100 GeV. Through a systematic study with respect to source significance, background level and source morphology we were able to derive optimal deconvolution parameters. The results presented show that deconvolution makes it possible to study structural details well below the angular resolution of the very high-energy gamma-ray experiment. (C) 2012 Elsevier B.V. All rights reserved. KW - Very high energy gamma-ray astronomy KW - Deconvolution Y1 - 2012 U6 - https://doi.org/10.1016/j.astropartphys.2012.05.013 SN - 0927-6505 VL - 36 IS - 1 SP - 146 EP - 150 PB - ELSEVIER SCIENCE BV CY - AMSTERDAM ER - TY - JOUR A1 - Girbig, Dorothee A1 - Grimbs, Sergio A1 - Selbig, Joachim T1 - Systematic analysis of stability patterns in plant primary metabolism JF - PLoS one N2 - Metabolic networks are characterized by complex interactions and regulatory mechanisms between many individual components. These interactions determine whether a steady state is stable to perturbations. Structural kinetic modeling (SKM) is a framework to analyze the stability of metabolic steady states that allows the study of the system Jacobian without requiring detailed knowledge about individual rate equations. Stability criteria can be derived by generating a large number of structural kinetic models (SK-models) with randomly sampled parameter sets and evaluating the resulting Jacobian matrices. Until now, SKM experiments applied univariate tests to detect the network components with the largest influence on stability. In this work, we present an extended SKM approach relying on supervised machine learning to detect patterns of enzyme-metabolite interactions that act together in an orchestrated manner to ensure stability. We demonstrate its application on a detailed SK-model of the Calvin-Benson cycle and connected pathways. The identified stability patterns are highly complex reflecting that changes in dynamic properties depend on concerted interactions between several network components. In total, we find more patterns that reliably ensure stability than patterns ensuring instability. This shows that the design of this system is strongly targeted towards maintaining stability. We also investigate the effect of allosteric regulators revealing that the tendency to stability is significantly increased by including experimentally determined regulatory mechanisms that have not yet been integrated into existing kinetic models. Y1 - 2012 U6 - https://doi.org/10.1371/journal.pone.0034686 SN - 1932-6203 VL - 7 IS - 4 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Lazareva, Nataliya F. A1 - Shainyan, Bagrat A. A1 - Schilde, Uwe A1 - Chipania, Nina N. T1 - Synthesis, Molecular Structure, Conformational Analysis, and Chemical Properties of Silicon-Containing Derivatives of Quinolizidine Y1 - 2012 SN - 0022-3263 ER - TY - JOUR A1 - Lazareva, Nataliya F. A1 - Shainyan, Bagrat A. A1 - Schilde, Uwe A1 - Chipanina, Nina N. A1 - Oznobikhina, Larisa P. A1 - Albanov, Alexander I. A1 - Kleinpeter, Erich T1 - Synthesis, molecular structure, conformational analysis, and chemical properties of silicon-containing derivatives of quinolizidine JF - The journal of organic chemistry N2 - A silicon analog of quinolizidine 3,3,7,7-tetramethylhexahydro-1H-[1,4,2]oxazasilino[4,5-d][1,4,2]oxazasilin-9a-yl)methanol 3 was synthesized. X-ray diffraction analysis confirmed the trans configuration and low temperature NMR spectroscopy both the flexibility (barrier of interconversion 5.8 kcal mol(-1)) and the conformational equilibrium (chair-chair and chair-twist conformers) of the compound. The relative stability of the different isomers/conformers of 3 was calculated also at the MP2/6-311G(d,p) level of theory. Intra- and intermolecular hydrogen bonding in 3 and the appropriate equilibrium between free and self-associated molecules was studied in solvents of different polarity. Both the N-methyl quaternary ammonium salt and the O-trimethylsilyl derivative of 3 could be obtained and their structure determined. Y1 - 2012 U6 - https://doi.org/10.1021/jo202658n SN - 0022-3263 VL - 77 IS - 5 SP - 2382 EP - 2388 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Najafpour, Mohammad Mahdi A1 - Hillier, Warwick A1 - Shamkhali, Amir Nasser A1 - Amini, Mojtaba A1 - Beckmann, Katrin A1 - Jaglicic, Zvonko A1 - Jagodic, Marko A1 - Strauch, Peter A1 - Moghaddam, Atefeh Nemati A1 - Beretta, Giangiacomo A1 - Bagherzadeh, Mojtaba T1 - Synthesis, characterization, DFT studies and catalytic activities of manganese(II) complex with 1,4-bis(2,2 ':6,2 ''-terpyridin-4 '-yl) benzene JF - Dalton transactions : a journal of inorganic chemistry, including bioinorganic, organometallic, and solid-state chemistry N2 - A new di-manganese complex with "back-to-back" 1,4-bis(2,2':6,2 ''-terpyridin-4'-yl) benzene ligation has been synthesized and characterised by a variety of techniques. The back-to-back ligation presents a novel new mononuclear manganese catalytic centre that functions as a heterogeneous catalysis for the evolution of oxygen in the presence of an exogenous oxidant. We discuss the synthesis and spectroscopic characterizations of this complex and propose a mechanism for oxygen evolution activity of the compound in the presence of oxone. The di-manganese complex also shows efficient and selective catalytic oxidation of sulfides in the presence of H2O2. Density functional theory calculations were used to assess the structural optimization of the complex and a proposed reaction pathway with oxone. The calculations show that middle benzene ring is distorted respect to both of metallic centers, and this in turn leads to negligible resonance of electrons between two sides of complex. The calculations also indicate the unpaired electron located on oxyl-ligand emphasizes the radical mechanism of water oxidation for the system. Y1 - 2012 U6 - https://doi.org/10.1039/c2dt31544k SN - 1477-9226 VL - 41 IS - 39 SP - 12282 EP - 12288 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Stojanovic, Milovan A1 - Markovic, Rade A1 - Baranac-Stojanovic, Marija T1 - Synthesis of thiazolidine-fused heterocycles via exo-mode cyclizations of vinylogous N-acyliminium ions N2 - Syntheses of thiazolidine-fused heterocycles via exo-mode cyclizations of vinylogous N-acyliminium ions incorporating heteroatom-based nucleophiles have been examined and discussed. The formation of (5,6)-membered systems was feasible with all nucleophiles tried (O, S and N), while the closing of the five-membered ring was restricted to O- and S-nucleophiles. The closure of a four-membered ring failed. Instead, the bicyclic (5,6)-membered acetal derivative and the tricyclic system with an eight-membered central ring were obtained from the substrates containing O and S nucleophilic moieties, respectively. The reaction outcome and stereochemistry are rationalized using quantum chemical calculations at B3LYP/6-31G(d) level. The exclusive cis-stereoselectivity in the formation of (5,6)- and (5,5)-membered systems results from thermodynamic control, whereas the formation of the eight-membered ring was kinetically controlled. Y1 - 2012 SN - 1477-0520 ER - TY - JOUR A1 - Stojanovic, Milovan A1 - Markovic, Rade A1 - Kleinpeter, Erich A1 - Baranac-Stojanovic, Marija T1 - Synthesis of thiazolidine-fused heterocycles via exo-mode cyclizations of vinylogous N-acyliminium ions JF - Organic & biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry N2 - Syntheses of thiazolidine-fused heterocycles via exo-mode cyclizations of vinylogous N-acyliminium ions incorporating heteroatom-based nucleophiles have been examined and discussed. The formation of (5,6)-membered systems was feasible with all nucleophiles tried (O, S and N), while the closing of the five-membered ring was restricted to O- and S-nucleophiles. The closure of a four-membered ring failed. Instead, the bicyclic (5,6)-membered acetal derivative and the tricyclic system with an eight-membered central ring were obtained from the substrates containing O and S nucleophilic moieties, respectively. The reaction outcome and stereochemistry are rationalized using quantum chemical calculations at B3LYP/6-31G(d) level. The exclusive cis-stereoselectivity in the formation of (5,6)- and (5,5)-membered systems results from thermodynamic control, whereas the formation of the eight-membered ring was kinetically controlled. Y1 - 2012 U6 - https://doi.org/10.1039/c1ob06451g SN - 1477-0520 VL - 10 IS - 3 SP - 575 EP - 589 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Modarresi-Alam, Ali Reza A1 - Inaloo, Iman Dindarloo T1 - Synthesis of primary thiocarbamates by silica sulfuric acid as effective reagent under solid-state and solution conditions N2 - A simple and efficient method for the conversion of alcohols and phenols to primary O-thiocarbamates and S- thiocarbamates in the absence of solvent (solvent-free condition) using silica sulfuric acid (SiO2OSO3H) as a solid acid is described. The products are easily distinguished by IR, NMR and X-ray data. X-ray data of the compounds reveal a planar trigonal orientation of the NH2 nitrogen atom with the partial C,N double-bond character and the CS or CO groups in synperiplanar position with CarylO and CalkylS moieties, respectively. Moreover, the OCSNH2 group which is perpendicular to the plane of the benzene ring in 1c and the central thiocarbamate SCONH2 group in 2b are essentially planar. Y1 - 2012 SN - 0022-2860 ER - TY - JOUR A1 - Modarresi-Alam, Ali Reza A1 - Inaloo, Iman Dindarloo A1 - Kleinpeter, Erich T1 - Synthesis of primary thiocarbamates by silica sulfuric acid as effective reagent under solid-state and solution conditions JF - Journal of molecular structure N2 - A simple and efficient method for the conversion of alcohols and phenols to primary O-thiocarbamates and S-thiocarbamates in the absence of solvent (solvent-free condition) using silica sulfuric acid (equivalent to SiO2-OSO3H) as a solid acid is described. The products are easily distinguished by IR, NMR and X-ray data. X-ray data of the compounds reveal a planar trigonal orientation of the NH2 nitrogen atom with the partial C,N double-bond character and the C=S or C=O groups in synperiplanar position with C-aryl-O and C-alkyl-S moieties, respectively. Moreover, the -O-CS-NH2 group which is perpendicular to the plane of the benzene ring in 1c and the central thiocarbamate -S-CO-NH2 group in 2b are essentially planar. KW - Solvent-free KW - N-unsubstituted(primary)O-thiocarbamates KW - N-unsubstituted (primary)S-thiocarbamates KW - Isothiocyanic acid KW - Solid acid KW - Silica sulfuric acid Y1 - 2012 U6 - https://doi.org/10.1016/j.molstruc.2012.05.033 SN - 0022-2860 VL - 1024 IS - 9 SP - 156 EP - 162 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Goebel, Ronald A1 - Xie, Zai-Lai A1 - Neumann, Mike A1 - Günter, Christina A1 - Loebbicke, Ruben A1 - Kubo, Shiori A1 - Titirici, Maria-Magdalena A1 - Giordano, Cristina A1 - Taubert, Andreas T1 - Synthesis of mesoporous carbon/iron carbide hybrids with unusually high surface areas from the ionic liquid precursor [Bmim][FeCl4] JF - CrystEngComm N2 - Mesoporous carbon/iron carbide hybrid materials with surface areas reaching 800 m(2) g(-1) were synthesized via an exotemplating route using monolithic mesoporous silica as template and the ionic liquid 1-butyl-3-methylimidazolium tetrachloridoferrate(III) [Bmim][FeCl4] as carbon and iron source. After heat treatment (750 degrees C under argon) of the [Bmim][FeCl4] precursor confined within the silica matrix, the silica exotemplate was removed with HF leaving the mesoporous C/Fe3C hybrid behind. The surface areas and the pore sizes depend on the exotemplate and the surface areas a significantly larger than any other surface area reported for C/Fe3C hybrid materials so far. The approach is thus a prototype for the synthesis of high-surface area iron carbide-based hybrid materials with potential application in catalysis. Y1 - 2012 U6 - https://doi.org/10.1039/c2ce25064k SN - 1466-8033 VL - 14 IS - 15 SP - 4946 EP - 4951 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Koeth, Anja A1 - Tiersch, Brigitte A1 - Appelhans, Dietmar A1 - Gradzielski, Michael A1 - Cölfen, Helmut A1 - Koetz, Joachim T1 - Synthesis of Core-Shell Gold Nanoparticles with Maltose-Modified Poly(Ethyleneimine) JF - Journal of dispersion science and technology N2 - The synthesis of ultrafine gold nanoparticles in presence of maltose-modified hyperbranched poly(ethyleneimines) (PEI) is described. The polymer acted as both a reducing and stabilising agent in the particle formation process. The nanoparticles were characterized by means of dynamic light scattering (DLS), transmission electron microscopy (TEM), analytical ultracentrifugation (AUC), small-angle x-ray scattering (SAXS), and small-angle neutron scattering (SANS). The mechanism of nanoparticle formation can be described in two steps. The reduction process of the Au3+ ions located in the inner coil region of the hyperbranched PEI led to the formation of a compact gold core, and is accompanied by a collapse of the polymer coil. Therefore, in the subsequent reduction process a gold-polymer hybrid shell is formed. By using the PEI of higher molar mass, core-shell gold nanoparticles of about 3.6 nm size with a more narrow size distribution and special fluorescence behavior could be synthesized. KW - Gold nanoparticles KW - gold-polymer hybrid shell KW - maltose-modified poly(ethyleneimine) Y1 - 2012 U6 - https://doi.org/10.1080/01932691.2010.530084 SN - 0193-2691 VL - 33 IS - 1-3 SP - 52 EP - 60 PB - Taylor & Francis Group CY - Philadelphia ER - TY - JOUR A1 - Schmidt, Bernd A1 - Krehl, Stefan A1 - Sotelo-Meza, Veronica T1 - Synthesis of chromanes through RCM-Transfer hydrogenation JF - Synthesis N2 - A sequential ruthenium-catalyzed ring-closing metathesis-transfer hydrogenation sequence has been established as a synthesis of chromanes starting from 2-(allyloxy)styrenes. The sequence requires only one precatalyst, the first-generation Grubbs catalyst, which is converted into a ruthenium hydride species in situ. Propan-2-ol serves as a chemical trigger for the formation of the ruthenium hydride and as hydrogen source. KW - ruthenium KW - chromanes KW - tandem reactions KW - metathesis KW - styrenes Y1 - 2012 U6 - https://doi.org/10.1055/s-0031-1289758 SN - 0039-7881 VL - 44 IS - 11 SP - 1603 EP - 1613 PB - Thieme CY - Stuttgart ER - TY - JOUR A1 - Schmidt, Bernd A1 - Krehl, Stefan A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Synthesis of 8-Aryl-Substituted Coumarins based on Ring-Closing Metathesis and Suzuki-Miyaura coupling - synthesis of a Furyl Coumarin natural product from Galipea panamensis JF - The journal of organic chemistry N2 - The synthesis of 7-methoxy-8-(4-methyl-3-furyl)-2H-chromen-2-one, a natural product with antileishmanial activity recently isolated from the plant Galipea panamensis, is described. The key step is a Suzuki-Miyaura coupling of a furan-3-boronic acid and an 8-halocoumarin, which is advantageously synthesized using a ring-closing metathesis reaction. Several non-natural analogues are also available along these lines. Y1 - 2012 U6 - https://doi.org/10.1021/jo2026564 SN - 0022-3263 VL - 77 IS - 5 SP - 2360 EP - 2367 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Bomm, Jana A1 - Günter, Christina A1 - Stumpe, Joachim T1 - Synthesis and optical characterization of thermosensitive, luminescent gold nanodots JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - A facile one-pot synthesis for preparing thermosensitive, luminescent gold nanodots with diameters of 1-2 nm is presented. The influence of the alkyl chain length of the surface ligands (alkyl thiols) on the optical properties of the gold nanodots was investigated. The synthesized gold nanodots show strong thermosensitive photoluminescence. A photoluminescence quantum yield of 16.6% was observed at room temperature, which could be improved to a value of 28.6% when cooling the gold nanodot solutions to -7 degrees C. The synthesized thermosensitive, luminescent gold nanodots are interesting candidates for optoelectronic devices, medical imaging, sensing, or security labels. Y1 - 2012 U6 - https://doi.org/10.1021/jp206260r SN - 1932-7447 VL - 116 IS - 1 SP - 81 EP - 85 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Heydenreich, Matthias A1 - Koch, Andreas A1 - Linker, Torsten T1 - Synthesis and NMR spectroscopic conformational analysis of esters of 4-hydroxy-cyclohexanone-the more polar the molecule the more stable the axial conformer N2 - The esters of 4-hydroxy-cyclohexanone and a series of carboxylic acids R-COOH with R of different electronic and steric influence (R=Me, Et, n-Pr, i-Pr, n-Bu, i-Bu, sec-Bu, t-Bu, CF3, CH2Cl, CHCl2, CCl3, CH2Br, CHBr2, and CBr3) were synthesized and the conformational equilibria studied by 1H and 13C NMR spectroscopy at 103 K and at 295 K, respectively. The geometry of optimized structures of the axial/equatorial chair conformers was computed at the ab initio MO and DFT levels of theory. Only one preferred conformation was obtained for the axial and the equatorial conformer as well. When comparing the conformational equilibria of the cyclohexanone esters with those of the corresponding cyclohexyl esters a certain polarity contribution of the cyclohexanone framework was revealed, which is independent of the substituent effects and increases the stability of the axial conformers by a constant amount. Y1 - 2012 SN - 0040-4020 ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Heydenreich, Matthias A1 - Koch, Andreas A1 - Linker, Torsten T1 - Synthesis and NMR spectroscopic conformational analysis of esters of 4-hydroxy-cyclohexanone-the more polar the molecule the more stable the axial conformer JF - Tetrahedron N2 - The esters of 4-hydroxy-cyclohexanone and a series of carboxylic acids R-COOH with R of different electronic and steric influence (R=Me, Et, n-Pr, i-Pr, n-Bu, i-Bu, sec-Bu, t-Bu, CF3, CH2Cl, CHCl2, CCl3, CH2Br, CHBr2, and CBr3) were synthesized and the conformational equilibria studied by H-1 and C-13 NMR spectroscopy at 103 K and at 295 K, respectively. The geometry of optimized structures of the axial 'equatorial chair conformers was computed at the ab initio MO and DFT levels of theory. Only one preferred conformation was obtained for the axial and the equatorial conformer as well. When comparing the conformational equilibria of the cyclohexanone esters with those of the corresponding cyclohexyl esters a certain polarity contribution of the cyclohexanone framework was revealed, which is independent of the substituent effects and increases the stability of the axial conformers by a constant amount. KW - 4-Substituted cyclohexanones KW - Conformational analysis KW - Dynamic NMR KW - Simulation of H-1 NMR spectra KW - Quantum chemical calculations KW - ALTONA equation Y1 - 2012 U6 - https://doi.org/10.1016/j.tet.2012.01.022 SN - 0040-4020 VL - 68 IS - 10 SP - 2363 EP - 2373 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Lazareva, Nataliya F. A1 - Albanov, Alexander I. A1 - Shainyan, Bagrat A. A1 - Kleinpeter, Erich T1 - Synthesis and conformational properties of substituted 1,4,2-oxazasilinanes: low temperature NMR study and quantum chemical calculations Y1 - 2012 UR - http://www.sciencedirect.com/science/article/pii/S0040402011018321 U6 - https://doi.org/10.1016/j.tet.2011.11.077 ER - TY - JOUR A1 - Lazareva, Nataliya F. A1 - Albanov, Alexander I. A1 - Shainyan, Bagrat A. A1 - Kleinpeter, Erich T1 - Synthesis and conformational properties of substituted 1,4,2-oxazasilinanes low temperature NMR study and quantum chemical calculations JF - Tetrahedron N2 - A number of N-substituted 2,2-dimethyl-1,4,2-oxazasilinanes 1 were synthesized and studied by variable temperature dynamic H-1 and C-13 NMR spectroscopy, room temperature N-15 NMR spectroscopy and theoretical calculations at the DFT and MP2 levels of theory. Both the preferred conformers were assigned and the barrier to the ring inversion of the saturated six-membered ring determined. From 1 the corresponding methyl iodide salts were produced, their structure studied by X-ray analysis and found to be in excellent agreement with the results of the theoretical calculations. KW - 1,4,2-Oxazasilinanes KW - Conformational analysis KW - Dynamic NMR KW - X-ray analysis KW - Quantum chemical calculations Y1 - 2012 U6 - https://doi.org/10.1016/j.tet.2011.11.077 SN - 0040-4020 VL - 68 IS - 4 SP - 1097 EP - 1104 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Shainyan, Bagrat A. A1 - Kirpichenko, Svetlana V. A1 - Kleinpeter, Erich T1 - Synthesis and conformational properties of 1,3-dimethyl-3-phenyl-1,3-azasilinane low temperature dynamic NMR and computational study JF - Arkivoc : free online journal of organic chemistry N2 - 1,3-Dimethyl-3-phenyl-1,3-azasilinane was synthesized and its conformational behavior was studied by the low temperature NMR spectroscopy and quantum chemical calculations. The compound was shown to exist as an equilibrium mixture of the PhaxMeeq and PheqMeax chair conformers with the N-methyl substituent in equatorial position. The barrier to ring inversion was also determined. KW - 1,3-Dimethyl-3-phenyl-1,3-azasilinane KW - conformational analysis KW - low temperature NMR spectroscopy KW - quantum chemical calculations Y1 - 2012 SN - 1551-7004 IS - 24 SP - 175 EP - 185 PB - ARKAT CY - Gainesville ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Schainyan, Bagrat A. A1 - Kirpichenko, Svetlane V. T1 - Synthesis and conformational properties of 1,3-dimethyl-3-phenyl-1,3-azasilinane : low temperature dynamic NMR and computational study N2 - 1,3-Dimethyl-3-phenyl-1,3-azasilinane was synthesized and its conformational behavior was studied by the low temperature NMR spectroscopy and quantum chemical calculations. The compound was shown to exist as an equilibrium mixture of the PhaxMeeq and PheqMeax chair conformers with the N-methyl substituent in equatorial position. The barrier to ring inversion was also determined. Y1 - 2012 SN - 1551-7004 ER - TY - JOUR A1 - Shainyan, Bagrat A. A1 - Kirpichenko, Svetlana V. A1 - Kleinpeter, Erich T1 - Synthesis and conformational analysis of 1,3-azasilinanes JF - Tetrahedron N2 - 1-Isopropyl-3-methyl-3-phenyl-1,3-azasilinane 1 and 1-isopropyl-3,3-dimethyl-1,3-azasilinane 2 were synthesized and a detailed analysis of their NMR spectra, conformational equilibria and ring inversion processes is presented. Low temperature H-1/C-13 NMR spectroscopy, iteration of the H-1 NMR spectra and quantum chemical calculations showed slight predominance of the PheqMeax over the PhaxMeeq conformer of 1 at low temperature. The barrier for the chair to chair interconversion of both compounds was measured to be 8.25 kcal/mol. KW - 1,3-Azasilinanes KW - Conformational analysis KW - Dynamic NMR spectroscopy KW - Quantum chemical calculations KW - Ring current effect Y1 - 2012 U6 - https://doi.org/10.1016/j.tet.2012.05.106 SN - 0040-4020 VL - 68 IS - 36 SP - 7494 EP - 7501 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Melchert, Christian A1 - Yongvongsoontorn, Nunnarpas A1 - Behl, Marc A1 - Lendlein, Andreas T1 - Synthesis and characterization of telechelic oligoethers with terminal cinnamylidene acetic acid moieties JF - Journal of applied biomaterials & functional materials N2 - Purpose: The formation of photoresponsive hydrogels were reported by irradiation of star-shaped poly(ethylene glycol)s with terminal cinnamylidene acetic acid (CAA) groups, which are capable of a photoinduced [2+2] cycloaddition. In this study we explored whether oligo(ethylene glycol) s and oligo(propylene glycol)s of varying molecular architecture (linear or star-shaped) or molecular weights could be functionalized with CAA as terminal groups by esterification or by amide formation. Methods: Oligo(ethylene glycol) (OEG) and oligo(propylene glycol) (OPG) with varying molecular architecture (linear, star-shaped) and weight average molecular weights between 1000 and 5000 g.mol(-1) were functionalized by means of esterification of hydroxyl or amine endgroups with cinnamylidene acetic acid (CAA) or cinnamylidene acetyl chloride (CAC) as telechelic endgroups. The chemical structure, thermal properties, and molecular weights of the oligoethers obtained were determined by NMR spectroscopy, UV spectroscopy, DSC, and MALDI-TOF. Results: CAA-functionalized linear and star-shaped OEGs or OPGs could be obtained with a degree of functionalization higher than 90%. In MALDI-TOF measurements an increase in Mw of about 150 g.mol(-1) (for each terminal end) after the functionalization reaction was observed. OEGCAA and OPGCAA showed an increase in glass transition temperature (T-g) from about -70 degrees C to -50 degrees C, compared to the unfunctionalized oligoethers. In addition, the melting temperature (T-m) of OEGCAA decreased from about 55 C to 30 degrees C, which can be accounted for by the hampered crystallization of the precursors because of the bulky CAA end groups as well as by the loss of the hydroxyl telechelic end groups. Conclusion: The synthesis of photoresponsive oligoethers containing cinnamylidene acetic acid as telechelic endgroup was reported and high degrees of functionalization could be achieved. Such photosensitive oligomers are promising candidates as reactive precursors, for the preparation of biocompatible high molecular weight polymers and polymer networks. KW - Biocompatible polymers KW - Cinnamylidene acetic acid KW - Photoresponsive polymers Y1 - 2012 U6 - https://doi.org/10.5301/JABFM.2012.10364 SN - 2280-8000 VL - 10 IS - 3 SP - 185 EP - 190 PB - Wichtig CY - Milano ER - TY - JOUR A1 - Paz, Cristian A1 - Peter, Martin G. A1 - Schmidt, Bernd A1 - Becerra, Jose A1 - Gutierrez, Margarita A1 - Astudillo, Luis A1 - Silva, Mario T1 - Synthesis and AChE inhibiting activity of 2, 4 substituted 6-Phenyl Pyrimidines JF - Journal of the Chilean Chemical Society N2 - Novel substituted pyrimidines were synthesized from methyl 2,4-dioxo-4-phenyl-butanoate (I-A) and urea, followed by Mitsunobu coupling of I-A with benzyl or allyl alcohol to give the corresponding 2-hydroxypyrimidine ethers in good yields. Saponification of I-A, followed by reaction with benzyl or allyl amines in the presence of TBTU yielded 2-hydroxy-6-phenyl-pyrimidine 4-carboxamides. AChE and BuChE assays revealed 2-hydroxy-6-phenyl-pyrimidine-4-carboxyallyamide as the most active compound, IC50=90 mu M, with no inhibition of BuChE. KW - Pyrimidines KW - inhibition AChE KW - mitsunobu KW - TBTU Y1 - 2012 SN - 0717-9324 VL - 57 IS - 3 SP - 1292 EP - 1294 PB - Sociedad Chilena De Quimica CY - Concepcion ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Csütörtöki, Renáta A1 - Szatmári, István A1 - Koch, Andreas A1 - Fulop, Ferenc T1 - Syntheses and conformational analyses of new naphth[1,2-e][1,3]oxazino[3,2-c]quinazolin-13-ones N2 - The syntheses of naphth[1,2-e][1,3]oxazino[3,2-c]quinazolin-13-one derivatives (3a-f) were achieved by the solvent-free heating of benzyloxycarbonyl-protected intermediates (2a-f) with MeONa. For intermediates 2a-f, prepared by the reactions of substituted aminonaphthols with benzyl N-(2-formylphenyl)carbamate, not only the expected trans ring form B and chain form A1, but also the rearranged chain form A2 as a new tautomer were detected in DMSO at room temperature. The quantity of A2 in the tautomeric mixture was changed with time. Conformational analyses of the target heterocycles 3a-f by NMR spectroscopy and accompanying theoretical calculations at the DFT level of theory revealed that the oxazine ring preferred a twisted chair conformation and the quinazolone ring was planar. Besides the conformations, both the configurations at C-7a and C-15 and the preferred rotamers of the 1-naphthyl substituent at C-15 were assigned, which allowed evaluation of the aryl substituent-dependent steric hindrance in this part of the molecules. Configurational assignments were corroborated by quantifying the ring current effect of 15-aryl in terms of spatial NICS. Y1 - 2012 ER - TY - JOUR A1 - Csütörtöki, Renata A1 - Szatmari, Istvan A1 - Koch, Andreas A1 - Heydenreich, Matthias A1 - Kleinpeter, Erich A1 - Fulop, Ferenc T1 - Syntheses and conformational analyses of new naphth[1,2-e][1,3]oxazino[3,2-c] quinazolin-13-ones JF - Tetrahedron N2 - The syntheses of naphth[1,2-e][1,3]oxazino[3,2-c]quinazolin-13-one derivatives (3a-f) were achieved by the solvent-free heating of benzyloxycarbonyl-protected intermediates (2a-f) with MeONa. For intermediates 2a-f, prepared by the reactions of substituted aminonaphthols with benzyl N-(2-formylphenyl)carbamate, not only the expected trans ring form B and chain form A(1), but also the rearranged chain form A(2) as a new tautomer were detected in DMSO at room temperature. The quantity of A(2) in the tautomeric mixture was changed with time. Conformational analyses of the target heterocycles 3a-f by NMR spectroscopy and accompanying theoretical calculations at the DFT level of theory revealed that the oxazine ring preferred a twisted chair conformation and the quinazolone ring was planar. Besides the conformations, both the configurations at C-7a and C-15 and the preferred rotamers of the 1-naphthyl substituent at C-15 were assigned, which allowed evaluation of the aryl substituent-dependent steric hindrance in this part of the molecules. Configurational assignments were corroborated by quantifying the ring current effect of 15-aryl in terms of spatial NICS. KW - Naphthoxazinoquinazolinones KW - Aminonaphthols KW - NMR spectroscopy KW - Conformational analysis KW - Theoretical calculations KW - Ring current effect Y1 - 2012 U6 - https://doi.org/10.1016/j.tet.2012.04.026 SN - 0040-4020 VL - 68 IS - 24 SP - 4600 EP - 4608 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Risse, Sebastian A1 - Kussmaul, Bjoern A1 - Krüger, Hartmut A1 - Kofod, Guggi T1 - Synergistic improvement of actuation properties with compatibilized high permittivity filler JF - Advanced functional materials N2 - Electroactive polymers can be used for actuators with many desirable features, including high electromechanical energy density, low weight, compactness, direct voltage control, and complete silence during actuation. These features may enable personalized robotics with much higher ability to delicately manipulate their surroundings than can be achieved with currently available actuators; however, much work is still necessary to enhance the electroactive materials. Electric field-driven actuator materials are improved by an increase in permittivity and by a reduction in stiffness. Here, a synergistic enhancement method based on a macromolecular plasticizing filler molecule with a combination of both high dipole moment and compatibilizer moieties, synthesized to simultaneously ensure improvement of electromechanical properties and compatibility with the host matrix is presented. Measurements show an 85% increase in permittivity combined with 290% reduction in mechanical stiffness. NMR measurements confirm the structure of the filler while DSC measurements confirm that it is compatible with the host matrix at all the mixture ratios investigated. Actuation strain measurements in the pure shear configuration display an increase in sensitivity to the electrical field of more than 450%, confirming that the filler molecule does not only improve dielectric and mechanical properties, it also leads to a synergistic enhancement of actuation properties by simple means. KW - allycyanide KW - silicone-based dielectric elastomer actuators KW - permittivity enhancement KW - compatibilized filler molecules Y1 - 2012 U6 - https://doi.org/10.1002/adfm.201200320 SN - 1616-301X VL - 22 IS - 18 SP - 3958 EP - 3962 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Navirian, H. A1 - Shayduk, R. A1 - Leitenberger, Wolfram A1 - Goldshteyn, J. A1 - Gaal, P. A1 - Bargheer, Matias T1 - Synchrotron-based ultrafast x-ray diffraction at high repetition rates JF - Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques N2 - We present a setup for ultrafast x-ray diffraction (UXRD) based at the storage ring BESSY II, in particular, a pump laser that excites the sample using 250 fs laser-pulses at repetition rates ranging from 208 kHz to 1.25 MHz. We discuss issues connected to the high heat-load and spatio-temporal alignment strategies in the context of a UXRD experiment at high repetition rates. The spatial overlap between laser pump and x-ray probe pulse is obtained with 10 mu m precision and transient lattice changes can be recorded with an accuracy of delta a/a(0) = 10(-6). We also compare time-resolved x-ray diffraction signals from a laser excited LSMO/STO superlattice with phonon dynamics simulations. From the analysis we determine the x-ray pulse duration to 120 ps in standard operation mode and below 10 ps in low-alpha mode. Y1 - 2012 U6 - https://doi.org/10.1063/1.4727872 SN - 0034-6748 VL - 83 IS - 6 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Zhong, Qi A1 - Metwalli, Ezzeldin A1 - Kaune, Gunar A1 - Rawolle, Monika A1 - Bivigou Koumba, Achille Mayelle A1 - Laschewsky, André A1 - Papadakis, Christine M. A1 - Cubitt, Robert A1 - Müller-Buschbaum, Peter T1 - Switching kinetics of thin thermo-responsive hydrogel films of poly(monomethoxy-diethyleneglycol-acrylate) probed with in situ neutron reflectivity JF - Soft matter N2 - The switching kinetics of thin thermo-responsive hydrogel films of poly(monomethoxy-diethyleneglycol-acrylate) (PMDEGA) are investigated. Homogeneous and smooth PMDEGA films with a thickness of 35.9 nm are prepared on silicon substrates by spin coating. As probed with white light interferometry, PMDEGA films with a thickness of 35.9 nm exhibit a phase transition temperature of the lower critical solution temperature (LCST) type of 40 degrees C. In situ neutron reflectivity is performed to investigate the thermo-responsive behavior of these PMDEGA hydrogel films in response to a sudden thermal stimulus in deuterated water vapor atmosphere. The collapse transition proceeds in a complex way which can be seen as three steps. The first step is the shrinkage of the initially swollen film by a release of water. In the second step the thickness remains constant with water molecules embedded in the film. In the third step, perhaps due to a conformational rearrangement of the collapsed PMDEGA chains, water is reabsorbed from the vapor atmosphere, thereby giving rise to a relaxation process. Both the shrinkage and relaxation processes can be described by a simple model of hydrogel deswelling. Y1 - 2012 U6 - https://doi.org/10.1039/c2sm25401h SN - 1744-683X VL - 8 IS - 19 SP - 5241 EP - 5249 PB - Royal Society of Chemistry CY - Cambridge ER - TY - THES A1 - Lohmann, Dirk T1 - Sustainable management of semi-arid African savannas under environmental and political change T1 - Nachhaltige Nutzung semiarider Savannen in Afrika unter dem Einfluss von klimatischem und politischem Wandel N2 - Drylands cover about 40% of the earth’s land surface and provide the basis for the livelihoods of 38% of the global human population. Worldwide, these ecosystems are prone to heavy degradation. Increasing levels of dryland degradation result a strong decline of ecosystem services. In addition, in highly variable semi-arid environments changing future environmental conditions will potentially have severe consequences for productivity and ecosystem dynamics. Hence, global efforts have to be made to understand the particular causes and consequences of dryland degradation and to promote sustainable management options for semi-arid and arid ecosystems in a changing world. Here I particularly address the problem of semi-arid savanna degradation, which mostly occurs in form of woody plant encroachment. At this, I aim at finding viable sustainable management strategies and improving the general understanding of semi-arid savanna vegetation dynamics under conditions of extensive livestock production. Moreover, the influence of external forces, i.e. environmental change and land reform, on the use of savanna vegetation and on the ecosystem response to this land use is assessed. Based on this I identify conditions and strategies that facilitate a sustainable use of semi-arid savanna rangelands in a changing world. I extended an eco-hydrological model to simulate rangeland vegetation dynamics for a typical semi-arid savanna in eastern Namibia. In particular, I identified the response of semi-arid savanna vegetation to different land use strategies (including fire management) also with regard to different predicted precipitation, temperature and CO2 regimes. Not only environmental but also economic and political constraints like e.g. land reform programmes are shaping rangeland management strategies. Hence, I aimed at understanding the effects of the ongoing process of land reform in southern Africa on land use and the semi-arid savanna vegetation. Therefore, I developed and implemented an agent-based ecological-economic modelling tool for interactive role plays with land users. This tool was applied in an interdisciplinary empirical study to identify general patterns of management decisions and the between-farm cooperation of land reform beneficiaries in eastern Namibia. The eco-hydrological simulations revealed that the future dynamics of semi-arid savanna vegetation strongly depend on the respective climate change scenario. In particular, I found that the capacity of the system to sustain domestic livestock production will strongly depend on changes in the amount and temporal distribution of precipitation. In addition, my simulations revealed that shrub encroachment will become less likely under future climatic conditions although positive effects of CO2 on woody plant growth and transpiration have been considered. While earlier studies predicted a further increase in shrub encroachment due to increased levels of atmospheric CO2, my contrary finding is based on the negative impacts of temperature increase on the drought sensitive seedling germination and establishment of woody plant species. Further simulation experiments revealed that prescribed fires are an efficient tool for semi-arid rangeland management, since they suppress woody plant seedling establishment. The strategies tested have increased the long term productivity of the savanna in terms of livestock production and decreased the risk for shrub encroachment (i.e. savanna degradation). This finding refutes the views promoted by existing studies, which state that fires are of minor importance for the vegetation dynamics of semi-arid and arid savannas. Again, the difference in predictions is related to the bottleneck at the seedling establishment stage of woody plants, which has not been sufficiently considered in earlier studies. The ecological-economic role plays with Namibian land reform beneficiaries showed that the farmers made their decisions with regard to herd size adjustments according to economic but not according to environmental variables. Hence, they do not manage opportunistically by tracking grass biomass availability but rather apply conservative management strategies with low stocking rates. This implies that under the given circumstances the management of these farmers will not per se cause (or further worsen) the problem of savanna degradation and shrub encroachment due to overgrazing. However, as my results indicate that this management strategy is rather based on high financial pressure, it is not an indicator for successful rangeland management. Rather, farmers struggle hard to make any positive revenue from their farming business and the success of the Namibian land reform is currently disputable. The role-plays also revealed that cooperation between farmers is difficult even though obligatory due to the often small farm sizes. I thus propose that cooperation needs to be facilitated to improve the success of land reform beneficiaries. N2 - Semiaride (halbtrockene) Savannen bedecken große Teile der Erdoberfläche und sichern die Lebensgrundlage von vielen Millionen Menschen. Die häufigste Form der Landnutzung in diesen Trockengebieten ist die Produktion von Vieh in extensiver Weidelandbewirtschaftung. In Folge klimatischer Veränderungen und als Konsequenz aus der teils intensiven Beweidung dieser Trockengebiete kommt es häufig zur Degradierung derselben in Form einer Zunahme von ‚unerwünschter‘ holziger Vegetation auf Kosten von futterverwertbaren Gräsern. Dieser als Verbuschung bezeichnete Prozess hat schwere negative Auswirkungen auf die betroffenen Ökosysteme und ist die Ursache für einen zunehmenden Rückgang der ökonomischen Leistungsfähigkeit der betroffenen Betriebe. In meiner Dissertation befasse ich mich mit den Auswirkungen von Klimawandel und politischen Veränderungen auf die Savannenvegetation im südlichen Afrika und auf die Möglichkeiten für die Nutzung dieser Ökosysteme in Form von Viehwirtschaft. Hierbei möchte ich sowohl das allgemeine Verständnis der ökologischen Zusammenhänge verbessern, als auch Strategien für die nachhaltige Nutzung der Savannen identifizieren und bewerten. Da nicht nur ökologische, sondern auch ökonomische und politische Einflussfaktoren, wie zum Beispiel die umfangreichen Landumverteilungen im Rahmen der Bodenreform im südlichen Afrika auf die tatsächliche Landnutzung wirken, habe ich im Rahmen der Dissertation zudem untersucht, nach welchen Umwelt und Kapitalvariablen sich die Farmer, welche Ihr Land im Rahmen der Bodenreform zugeteilt bekommen haben, bei Ihren Entscheidungen richten. Methodisch verwende ich verschiedene Simulationsmodelle, welche zur Untersuchung der langfristigen Veränderungen von verschiedensten Szenarien (Klimawandel, Landnutzung) geeignet sind. Hierbei habe ich teilweise bestehende Modelle angepasst, aber auch ein neues Modell, welches zur Befragung von Farmern in Namibia verwendet wurde, entwickelt. Meine Dissertation führt im Wesentlichen zu vier Erkenntnissen: Erstens, zeigen meine Ergebnisse, welche große Bedeutung die spezifischen ökologischen Eigenschaften der Bäume und Sträucher in semiariden Savannen für die Vorhersage der Entwicklung dieser Systeme unter Klimawandel hat. Hierbei zeigte sich, dass insbesondere die Sensitivität der Keimlinge gegenüber Trockenheit und Feuer eine entscheidende Rolle spielt. Daraus folgt die zweite wesentliche Erkenntnis: Feuer eignet sich in herausragender Weise, um halbtrockene Savannen vor der Verbuschung zu bewahren. Drittens haben die Rollenspiele mit Farmern in Namibia gezeigt, dass deren Entscheidungen im Wesentlichen von finanziellen Schwierigkeiten und nicht von Umwelteinflüssen getrieben werden. Dennoch zeigten meine Ergebnisse, dass diese Farmer mit Ihrem derzeitigen Verhalten wahrscheinlich nicht zur weiteren Degradierung der Savannenvegetation beitragen. Die vierte, und mit am bedeutendste Erkenntnis aus meiner Arbeit ist, dass konservative Beweidungsstrategien mit geringen und konstanten Viehdichten notwendig sind um semiaride Savannen dauerhaft in ökologisch und ökonomisch nachhaltiger Weise zu Nutzen. KW - Savanne KW - nachhaltige Landnutzung KW - ökohydrologische Modellierung KW - Land Reform KW - Klimawandel KW - Savanna KW - sustainable land use KW - eco-hydrological modelling KW - land reform KW - climate change Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-65069 ER - TY - THES A1 - Falco, Camillo T1 - Sustainable biomass-derived hydrothermal carbons for energy applications T1 - Nachhaltiger, Biomasse-basierter Hydrothermalkohlenstoff für Energieanwendungen N2 - The need to reduce humankind reliance on fossil fuels by exploiting sustainably the planet renewable resources is a major driving force determining the focus of modern material research. For this reason great interest is nowadays focused on finding alternatives to fossil fuels derived products/materials. For the short term the most promising substitute is undoubtedly biomass, since it is the only renewable and sustainable alternative to fossil fuels as carbon source. As a consequence efforts, aimed at finding new synthetic approaches to convert biomass and its derivatives into carbon-based materials, are constantly increasing. In this regard, hydrothermal carbonisation (HTC) has shown to be an effective means of conversion of biomass-derived precursors into functional carbon materials. However the attempts to convert raw biomass, in particular lignocellulosic one, directly into such products have certainly been rarer. Unlocking the direct use of these raw materials as carbon precursors would definitely be beneficial in terms of HTC sustainability. For this reason, in this thesis the HTC of carbohydrate and protein-rich biomass was systematically investigated, in order to obtain more insights on the potentials of this thermochemical processing technique in relation to the production of functional carbon materials from crude biomass. First a detailed investigation on the HTC conversion mechanism of lignocellulosic biomass and its single components (i.e. cellulose, lignin) was developed based on a comparison with glucose HTC, which was adopted as a reference model. In the glucose case it was demonstrated that varying the HTC temperature allowed tuning the chemical structure of the synthesised carbon materials from a highly cross-linked furan-based structure (T = 180oC) to a carbon framework composed of polyaromatic arene-like domains. When cellulose or lignocellulosic biomass was used as carbon precursor, the furan rich structure could not be isolated at any of the investigated processing conditions. These evidences were indicative of a different HTC conversion mechanism for cellulose, involving reactions that are commonly observed during pyrolytic processes. The evolution of glucose-derived HTC carbon chemical structure upon pyrolysis was also investigated. These studies revealed that upon heat treatment (Investigated temperatures 350 – 900 oC) the furan-based structure was progressively converted into highly curved aromatic pre-graphenic domains. This thermal degradation process was observed to produce an increasingly more hydrophobic surface and considerable microporosity within the HTC carbon structure. In order to introduce porosity in the HTC carbons derived from lignocellulosic biomass, KOH chemical activation was investigated as an HTC post-synthesis functionalisation step. These studies demonstrated that HTC carbons are excellent precursors for the production of highly microporous activated carbons (ACs) and that the porosity development upon KOH chemical activation is dependent on the chemical structure of the HTC carbon, tuned by employing different HTC temperatures. Preliminary testing of the ACs for CO2 capture or high pressure CH4 storage yielded very promising results, since the measured uptakes of both adsorbates (i.e. CO2 and CH4) were comparable to top-performing and commercially available adsorbents, usually employed for these end-applications. The combined use of HTC and KOH chemical activation was also employed to produce highly microporous N-doped ACs from microalgae. The hydrothermal treatment of the microalgae substrate was observed to cause the depletion of the protein and carbohydrate fractions and the near complete loss (i.e. 90%) of the microalgae N-content, as liquid hydrolysis/degradation products. The obtained carbonaceous product showed a predominantly aliphatic character indicating the presence of alkyl chains presumably derived from the lipid fractions. Addition of glucose to the initial reaction mixture was found out to be extremely beneficial, because it allowed the fixation of a higher N amount, in the algae derived HTC carbons (i.e.  60%), and the attainment of higher product yields (50%). Both positive effects were attributed to Maillard type cascade reactions taking place between the monosaccharides and the microalgae derived liquid hydrolysis/degradation products, which were in this way recovered from the liquid phase. KOH chemical activation of the microalgae/glucose mixture derived HTC carbons produced highly microporous N-doped carbons. Although the activation process led to a major reduction of the N-content, the retained N-amount in the ACs was still considerable. These features render these materials ideal candidates for supercapacitors electrodes, since they provide extremely high surface areas, for the formation of electric double-layer, coupled to abundant heteroatom doping (i.e. N and O) necessary to obtain a pseudocapacitance contribution. N2 - Die Notwendigkeit, die Abhängigkeit der Menschheit von fossilen Brennstoffen zu reduzieren ist die treibende Kraft hinter aktuellen Forschungsanstrengungen in den Materialwissenschaften. Folglich besteht heutzutage ein erhebliches Interesse daran Alternativen zu Materialien, die aus fossilen Resourcen gewonnen werden, zu finden. Kurzfristig ist zweifellos Biomasse die vielversprechendste Alternative, da sie aus heutiger Sicht die einzige nicht-fossile, nachhaltige und nachwachsende Kohlenstoffquelle ist. Konsequenterweise werden die Antrengungen neue Syntheseansätze zur Konvertierung von Biomasse und ihren Derivaten in kohlenstoffbasierten Materialien forwährend erhöht. In diesem Zusammenhang hat sich die Hydrothermalkarbonisierung (HTC) als sehr vielseitiges Werkzeug zur Konvertierung von Biomasse-basierten Ausgangsstoffen in funktionale Kohlenstoffmaterialien herausgestellt. Dennoch gibt es bisher wenige Ansätze um rohe Biomasse, genauer gesagt Lignicellulose, direkt in funktionale Materialien umzusetzen. Könnte der direkte Einsatz von roher Biomasse Verfahren wie der HTC zugänglich gemacht werden, würde dies die Nachhaltigkeit des Verfahrens immens steigern. Daher wurde in dieser Dissertation die Hydrothermalkarbonisierung von kohlenhydratreicher (d. h. Lignicelluse) und proteinreicher (d. h. Microalgae) Biomasse systematisch analysiert. Diese Untersuchung galt dem Ziel einen besseren Einblick in das Potential dieser thermochemischen Verarbeitungsmethode funktionale Kohlenstoffmaterialien aus unverarbeiteter Biomasse hervorzubringen zu gewinnen. Die hergestellten Materialien wurden mittels chemischer Aktivierung nachträglich weiter behandelt. Dieser zusätzliche Verarbeitungsschritt ermöglichte die Herstellung hochporöser aktiverter Kohlenstoffe (AC). Die aus Lignicellulose gewonnenen ACs zeigten exzellente Eigenschaften bei der Aufnahme von CO2 und der Hochdruckspeicherung von CH4 währen die aus Microalgae gewonnen Eigenschaften an den Tag legten (z. B. hohe Oberfläche und N-Dotierung), welche sie zu vielversprechenden Materialien für Superkondensatoren machen. Die in dieser Dissertation präsentierte Arbeit zeigte außergewöhnliche Fortschritte in Richtung der Anwendung von unbehandelter Biomasse als Ausgangsmaterial für die Produktion von funktionalen Kohlenstoffen. KW - Biomasse KW - Kohlenmaterialien KW - Grüne Chemie KW - Nachhaltigkeit KW - Enegieanwendungen KW - Biomass KW - Carbon materials KW - Green Chemistry KW - Sustainability KW - Energy Applications Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-59785 ER - TY - JOUR A1 - Horovitz, Baruch A1 - Henkel, Carsten T1 - Surface plasmons at composite surfaces with diffusive charges JF - epl : a letters journal exploring the frontiers of physics N2 - Metal surfaces with disorder or with nanostructure modifications are studied, allowing for a localized charge layer (CL) in addition to continuous charges (CC) in the bulk, both charges having a compressional or diffusive nonlocal response. The notorious problem of "additional boundary conditions" is resolved with the help of a Boltzmann equation that involves the scattering between the two charge types. Depending on the strength of this scattering, the oscillating charges can be dominantly CC or CL; the surface plasmon (SP) resonance acquires then a relatively small linewidth, in agreement with a large set of data. With a few parameters our model describes a large variety of SP dispersions corresponding to observed data. Y1 - 2012 U6 - https://doi.org/10.1209/0295-5075/97/57010 SN - 0295-5075 VL - 97 IS - 5 PB - EDP Sciences CY - Mulhouse ER - TY - JOUR A1 - König, Tobias A1 - Sekhar, Y. Nataraja A1 - Santer, Svetlana T1 - Surface plasmon nanolithography impact of dynamically varying near-field boundary conditions at the air-polymer interface JF - Journal of materials chemistry N2 - It is well-known that surface plasmon generated near fields of suitably irradiated metal nano-structures can induce a patterning in an azobenzene-modified photosensitive polymer film placed on top. The change in the topography usually follows closely and permanently the underlying near field intensity pattern. With this approach, one can achieve a multitude of morphologies by additionally changing light intensity, polarization and the kind of metal used for nano-structuring. In this paper, we demonstrate that below a critical value of the polymer film thickness, the receding polymer material induces a change in refractive index of the glass-metal-polymer system, modifying the near field intensity distribution and causing a back-reaction on the flow of polymer material. This has a profound influence on the smallest size of topographical features that can be imprinted into the polymer. Y1 - 2012 U6 - https://doi.org/10.1039/c2jm15864g SN - 0959-9428 VL - 22 IS - 13 SP - 5945 EP - 5950 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Floss, Gereon A1 - Granucci, Giovanni A1 - Saalfrank, Peter T1 - Surface hopping dynamics of direct trans -> cis photoswitching of an azobenzene derivative in constrained adsorbate geometries JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - With ongoing miniaturization of electronic devices, the need for individually addressable, switchable molecules arises. An example are azobenzenes on surfaces which have been shown to be switchable between trans and cis forms. Here, we examine the "direct" (rather than substrate-mediated) channel of the trans -> cis photoisomerization after pi pi* excitation of tetra-tert-butyl-azobenzene physisorbed on surfaces mimicking Au(111) and Bi(111), respectively. In spirit of the direct channel, the electronic structure of the surface is neglected, the latter merely acting as a rigid platform which weakly interacts with the molecule via Van-der-Waals forces. Starting from thermal ensembles which represent the trans-form, sudden excitations promote the molecules to pi pi*-excited states which are non-adiabatically coupled among themselves and to a n pi*-excited and the ground state, respectively. After excitation, relaxation to the ground state by internal conversion takes place, possibly accompanied by isomerization. The process is described here by "on the fly" semiclassical surface hopping dynamics in conjunction with a semiempirical Hamiltonian (AM1) and configuration-interaction type methods. It is found that steric constraints imposed by the substrate lead to reduced but non-vanishing, trans -> cis reaction yields and longer internal conversion times than for the isolated molecule. Implications for recent experiments for azobenzenes on surfaces are discussed. KW - AM1 calculations KW - bismuth KW - configuration interactions KW - excited states KW - gold KW - isomerisation KW - organic compounds KW - photochemistry KW - van der Waals forces Y1 - 2012 U6 - https://doi.org/10.1063/1.4769087 SN - 0021-9606 VL - 137 IS - 23 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Lange, Maik A1 - Braune, Steffen A1 - Luetzow, Karola A1 - Richau, Klaus A1 - Scharnagl, Nico A1 - Weinhart, Marie A1 - Neffe, Axel T. A1 - Jung, Friedrich A1 - Haag, Rainer A1 - Lendlein, Andreas T1 - Surface functionalization of poly(ether imide) membranes with linear, methylated oligoglycerols for reducing thrombogenicity JF - Macromolecular rapid communications N2 - Materials for biomedical applications are often chosen for their bulk properties. Other requirements such as a hemocompatible surface shall be fulfilled by suitable chemical functionalization. Here we show, that linear, side-chain methylated oligoglycerols (OGMe) are more stable to oxidation than oligo(ethylene glycol) (OEG). Poly(ether imide) (PEI) membranes functionalized with OGMes perform at least as good as, and partially better than, OEG functionalized PEI membranes in view of protein resistance as well as thrombocyte adhesion and activation. Therefore, OGMes are highly potent surface functionalizing molecules for improving the hemocompatibility of polymers. KW - hemocompatibility KW - poly(ethylene glycol) KW - polyglycerol KW - polyimides KW - surface chemistry Y1 - 2012 U6 - https://doi.org/10.1002/marc.201200426 SN - 1022-1336 VL - 33 IS - 17 SP - 1487 EP - 1492 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schildgen, Taylor F. A1 - Cosentino, D. A1 - Caruso, A. A1 - Buchwaldt, Robert A1 - Yildirim, C. A1 - Bowring, S. A. A1 - Rojay, B. A1 - Echtler, Helmut Peter A1 - Strecker, Manfred T1 - Surface expression of eastern Mediterranean slab dynamics: Neogene topographic and structural evolution of the southwest margin of the Central Anatolian Plateau, Turkey JF - TECTONICS N2 - The southwest margin of the Central Anatolian Plateau has experienced multiple phases of topographic growth, including the formation of localized highs prior to the Late Miocene that were later affected by wholesale uplift of the plateau margin. Our new biostratigraphic data limit the age of uplifted marine sediments at the southwest plateau margin at 1.5 km elevation to <7.17 Ma, and regional lithostratigraphic correlations imply that the age is <6.7 Ma. Single-grain CA-TIMS U-Pb zircon analyses from a reworked ash within the marine sediments yield dates as young as 10.6 Ma, indicating a maximum age that is consistent with the biostratigraphy. Our structural measurements within the uplifted region and fault inversion modeling agree with previous findings in surrounding regions, with early contraction followed by strike-slip and extensional deformation during uplift. Focal mechanisms from shallow earthquakes show that the extensional phase has continued to the present. Broad similarities in the change in the tectonic stress regime (after 8 Ma) and the onset of surface uplift (after 7 Ma) imply that deep-seated process(es) caused post-7 Ma uplift. The geometry of lithospheric slabs beneath the plateau margin, Pliocene to recent alkaline volcanism, and the uplift pattern with accompanying normal faulting point toward slab tearing and localized heating at the base of the lithosphere as a probable mechanism for post-7 Ma uplift of the southwest margin. Considering previous work in the region, there appears to be an important link between slab dynamics and surface uplift throughout the Anatolian Plateau’s southern margin. Y1 - 2012 U6 - https://doi.org/10.1029/2011TC003021 SN - 0278-7407 SN - 1944-9194 VL - 31 PB - AMER GEOPHYSICAL UNION CY - WASHINGTON ER - TY - JOUR A1 - Ellis, S. C. A1 - Bland-Hawthorn, Joss A1 - Lawrence, J. A1 - Horton, A. J. A1 - Trinh, C. A1 - Leon-Saval, S. G. A1 - Shortridge, K. A1 - Bryant, J. A1 - Case, S. A1 - Colless, M. A1 - Couch, W. A1 - Freeman, K. A1 - Gers, L. A1 - Glazebrook, K. A1 - Haynes, R. A1 - Lee, S. A1 - Löhmannsröben, Hans-Gerd A1 - O'Byrne, J. A1 - Miziarski, S. A1 - Roth, M. A1 - Schmidt, B. A1 - Tinney, C. G. A1 - Zheng, J. T1 - Suppression of the near-infrared OH night-sky lines with fibre Bragg gratings - first results JF - Monthly notices of the Royal Astronomical Society N2 - The background noise between 1 and 1.8 ?mu m in ground-based instruments is dominated by atmospheric emission from hydroxyl molecules. We have built and commissioned a new instrument, the Gemini Near-infrared OH Suppression Integral Field Unit (IFU) System (GNOSIS), which suppresses 103 OH doublets between 1.47 and 1.7?mu m by a factor of 1000 with a resolving power of 10?000. We present the first results from the commissioning of GNOSIS using the IRIS2 spectrograph at the Anglo-Australian Telescope. We present measurements of sensitivity, background and throughput. The combined throughput of the GNOSIS fore-optics, grating unit and relay optics is 36?per cent, but this could be improved to 46?per cent with a more optimal design. We measure strong suppression of the OH lines, confirming that OH suppression with fibre Bragg gratings will be a powerful technology for low-resolution spectroscopy. The integrated OH suppressed background between 1.5 and 1.7 mu m is reduced by a factor of 9 compared to a control spectrum using the same system without suppression. The potential of low-resolution OH-suppressed spectroscopy is illustrated with example observations of Seyfert galaxies and a low-mass star. The GNOSIS background is dominated by detector dark current below 1.67 mu m and by thermal emission above 1.67 mu m. After subtracting these, we detect an unidentified residual interline component of 860 +/- 210 photons s-1 m-2?arcsec-2?mu m-1, comparable to previous measurements. This component is equally bright in the suppressed and control spectra. We have investigated the possible source of the interline component, but were unable to discriminate between a possible instrumental artefact and intrinsic atmospheric emission. Resolving the source of this emission is crucial for the design of fully optimized OH suppression spectrographs. The next-generation OH suppression spectrograph will be focused on resolving the source of the interline component, taking advantage of better optimization for a fibre Bragg grating feed incorporating refinements of design based on our findings from GNOSIS. We quantify the necessary improvements for an optimal OH suppressing fibre spectrograph design. KW - atmospheric effects KW - instrumentation: miscellaneous KW - infrared: general Y1 - 2012 U6 - https://doi.org/10.1111/j.1365-2966.2012.21602.x SN - 0035-8711 VL - 425 IS - 3 SP - 1682 EP - 1695 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Quasthoff, Matthias A1 - Meinel, Christoph T1 - Supporting object-oriented programming of semantic-web software JF - IEEE transactions on systems, man, and cybernetics : Part C, Applications and reviews N2 - This paper presents the state of the art in the development of Semantic-Web-enabled software using object-oriented programming languages. Object triple mapping (OTM) is a frequently used method to simplify the development of such software. A case study that is based on interviews with developers of OTM frameworks is presented at the core of this paper. Following the results of the case study, the formalization of OTM is kept separate from optional but desirable extensions of OTM with regard to metadata, schema matching, and integration into the Semantic-Web infrastructure. The material that is presented is expected to not only explain the development of Semantic-Web software by the usage of OTM, but also explain what properties of Semantic-Web software made developers come up with OTM. Understanding the latter will be essential to get nonexpert software developers to use Semantic-Web technologies in their software. KW - Resource description framework KW - Software KW - Java KW - Data models KW - Programming KW - Interviews Y1 - 2012 U6 - https://doi.org/10.1109/TSMCC.2011.2151282 SN - 1094-6977 VL - 42 IS - 1 SP - 15 EP - 24 PB - Inst. of Electr. and Electronics Engineers CY - Piscataway ER - TY - JOUR A1 - de Vera, Jean-Pierre Paul A1 - Böttger, Ute A1 - de la Torre Nötzel, Rosa A1 - Sanchez, Francisco J. A1 - Grunow, Dana A1 - Schmitz, Nicole A1 - Lange, Caroline A1 - Hübers, Heinz-Wilhelm A1 - Billi, Daniela A1 - Baque, Mickael A1 - Rettberg, Petra A1 - Rabbow, Elke A1 - Reitz, Günther A1 - Berger, Thomas A1 - Möller, Ralf A1 - Bohmeier, Maria A1 - Horneck, Gerda A1 - Westall, Frances A1 - Jänchen, Jochen A1 - Fritz, Jörg A1 - Meyer, Cornelia A1 - Onofri, Silvano A1 - Selbmann, Laura A1 - Zucconi, Laura A1 - Kozyrovska, Natalia A1 - Leya, Thomas A1 - Foing, Bernard A1 - Demets, Rene A1 - Cockell, Charles S. A1 - Bryce, Casey A1 - Wagner, Dirk A1 - Serrano, Paloma A1 - Edwards, Howell G. M. A1 - Joshi, Jasmin Radha A1 - Huwe, Björn A1 - Ehrenfreund, Pascale A1 - Elsaesser, Andreas A1 - Ott, Sieglinde A1 - Meessen, Joachim A1 - Feyh, Nina A1 - Szewzyk, Ulrich A1 - Jaumann, Ralf A1 - Spohn, Tilman T1 - Supporting Mars exploration BIOMEX in Low Earth Orbit and further astrobiological studies on the Moon using Raman and PanCam technology JF - Planetary and space science N2 - The Low Earth Orbit (LEO) experiment Biology and Mars Experiment (BIOMEX) is an interdisciplinary and international space research project selected by ESA. The experiment will be accommodated on the space exposure facility EXPOSE-R2 on the International Space Station (ISS) and is foreseen to be launched in 2013. The prime objective of BIOMEX is to measure to what extent biomolecules, such as pigments and cellular components, are resistant to and able to maintain their stability under space and Mars-like conditions. The results of BIOMEX will be relevant for space proven biosignature definition and for building a biosignature data base (e.g. the proposed creation of an international Raman library). The library will be highly relevant for future space missions such as the search for life on Mars. The secondary scientific objective is to analyze to what extent terrestrial extremophiles are able to survive in space and to determine which interactions between biological samples and selected minerals (including terrestrial, Moon- and Mars analogs) can be observed under space and Mars-like conditions. In this context, the Moon will be an additional platform for performing similar experiments with negligible magnetic shielding and higher solar and galactic irradiation compared to LEO. Using the Moon as an additional astrobiological exposure platform to complement ongoing astrobiological LEO investigations could thus enhance the chances of detecting organic traces of life on Mars. We present a lunar lander mission with two related objectives: a lunar lander equipped with Raman and PanCam instruments which can analyze the lunar surface and survey an astrobiological exposure platform. This dual use of testing mission technology together with geo- and astrobiological analyses will significantly increase the science return, and support the human preparation objectives. It will provide knowledge about the Moon's surface itself and, in addition, monitor the stability of life-markers, such as cells, cell components and pigments, in an extraterrestrial environment with much closer radiation properties to the surface of Mars. The combination of a Raman data base of these data together with data from LEO and space simulation experiments, will lead to further progress on the analysis and interpretation of data that we will obtain from future Moon and Mars exploration missions. KW - Moon KW - Mars KW - Low Earth Orbit KW - Astrobiology KW - Instrumentation KW - Spectroscopy KW - Biosignature Y1 - 2012 U6 - https://doi.org/10.1016/j.pss.2012.06.010 SN - 0032-0633 VL - 74 IS - 1 SP - 103 EP - 110 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Ohuchi, Tomohiro A1 - Nishihara, Yu A1 - Kawazoe, Takaaki A1 - Spengler, Dirk A1 - Shiraishi, Rei A1 - Suzuki, Akio A1 - Kikegawa, Takumi A1 - Ohtani, Eiji T1 - Superplasticity in hydrous melt-bearing dunite Implications for shear localization in Earth's upper mantle JF - Earth & planetary science letters N2 - Deformation experiments on hydrous melt-bearing dunite (olivine+4 vol% orthopyroxene+4 vol% clinopyroxene with less than 2.5 vol% of the melt phase) were conducted at pressures of 1.3-5.7 GPa and temperatures of 1270-1490 K in order to explore the effect of intergranular fluids on the plastic flow of olivine in Earth's upper mantle. The strain rate was proportional to steady-state creep strength to the 2.1 power, and the creep strength markedly increased with increase in grain size. Developments of the crystallographic preferred orientation of olivine and flattening of olivine grains were hardly observed even after 33-55% shortening of the samples. These observations show that grain boundary sliding (GBS) dominated the deformation of olivine (i.e., superplasticity). The creep strength of hydrous melt-bearing dunite was 2-5 times lower than that of melt-free dunite. The dependence of creep rate on melt fraction is known to be expressed empirically as (epsilon) over dot(phi) = (epsilon) over dot(0) exp(alpha phi), where alpha is a constant and phi is the melt fraction. The experimentally obtained value of alpha was in the range of 150-230, corresponding to 5-7 times the reported values for the olivine-basalt system at 0.3 GPa (i.e., creep strength of dunite was efficiently reduced by the hydrous melt). Superplasticity is the dominant creep mechanism of olivine in fluid-bearing fine-grained peridotites under low-temperature and high-stress conditions (i.e., peridotite shear zones in the upper mantle). Superplasticity induced by geological fluids would play an important role in the shear localization (and thus initiation of subduction) in the upper mantle. KW - olivine KW - hydrous melt KW - grain boundary sliding KW - superplasticity KW - shear localization KW - subduction Y1 - 2012 U6 - https://doi.org/10.1016/j.epsl.2012.04.032 SN - 0012-821X VL - 335 IS - 12 SP - 59 EP - 71 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Böniger, Urs A1 - Tronicke, Jens T1 - Subsurface utility extraction and characterization combining GPR symmetry and polarization attributes JF - IEEE transactions on geoscience and remote sensing N2 - Polarization of the electromagnetic wavefield has significant implications for the acquisition and interpretation of ground-penetrating radar (GPR) data. Based on the geometrical and physical properties of the subsurface scatterer and the physical properties of its surrounding material, strong polarization phenomena might occur. Here, we develop an attribute-based analysis approach to extract and characterize buried utility pipes using two broadside antenna configurations. First, we enhance and extract the utilities by making use of their distinct symmetric nature through the application of a symmetry-enhancing image-processing algorithm known as phase symmetry. Second, we assess the polarization characteristics by calculating two attributes (polarization angle and linearity) using principal component analysis. Combination of attributes derived from these steps into a novel depolarization attribute allows one to efficiently detect and distinguish different utilities present within 3-D GPR data. The performance of our analysis approach is illustrated using synthetic examples and evaluated using field examples (including a dual-configuration 3-D data set) collected across a field site, where detailed ground-truth information is available. Our results demonstrate that the proposed approach allows for a more detailed extraction and combination of utility relevant information compared to approaches relying on single-component data and, thus, eases the interpretation of multicomponent GPR data sets. KW - Multicomponent ground-penetrating radar (GPR) data KW - phase symmetry KW - pipe detection KW - polarization analysis KW - principal component analysis (PCA) Y1 - 2012 U6 - https://doi.org/10.1109/TGRS.2011.2163413 SN - 0196-2892 SN - 1558-0644 VL - 50 IS - 3 SP - 736 EP - 746 PB - Inst. of Electr. and Electronics Engineers CY - Piscataway ER - TY - GEN A1 - Rothweiler, Monika A1 - Chilla, Solveig A1 - Clahsen, Harald T1 - Subject−verb agreement in Specific Language Impairment BT - a study of monolingual and bilingual German-speaking children T2 - Postprints der Universität Potsdam Humanwissenschaftliche Reihe N2 - This study investigates phenomena that have been claimed to be indicative of Specific Language Impairment (SLI) in German, focusing on subject-verb agreement marking. Longitudinal data from fourteen German-speaking children with SLI, seven monolingual and seven Turkish-German successive bilingual children, were examined. We found similar patterns of impairment in the two participant groups. Both the monolingual and the bilingual children with SLI had correct (present vs. preterit) tense marking and produced syntactically complex sentences such as embedded clauses and wh-questions, but were limited in reliably producing correct agreement-marked verb forms. These contrasts indicate that agreement marking is impaired in German-speaking children with SLI, without any necessary concurrent deficits in either the CP-domain or in tense marking. Our results also show that it is possible to identify SLI from an early successive bilingual child's performance in one of her two languages. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 510 KW - verb morphology KW - tense deficit KW - agreement deficit KW - Turkish−German SLI Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-415122 SN - 1866-8364 IS - 510 ER - TY - JOUR A1 - Rothweiler, Monika A1 - Chilla, Solveig A1 - Clahsen, Harald T1 - Subject-verb agreement in specific language impairment BT - a study of monolingual and bilingual German-speaking children JF - Bilingualism : language and cognition. N2 - This study investigates phenomena that have been claimed to be indicative of Specific Language Impairment (SLI) in German, focusing on subject-verb agreement marking. Longitudinal data from fourteen German-speaking children with SLI, seven monolingual and seven Turkish-German successive bilingual children, were examined. We found similar patterns of impairment in the two participant groups. Both the monolingual and the bilingual children with SLI had correct (present vs. preterit) tense marking and produced syntactically complex sentences such as embedded clauses and wh-questions, but were limited in reliably producing correct agreement-marked verb forms. These contrasts indicate that agreement marking is impaired in German-speaking children with SLI, without any necessary concurrent deficits in either the CP-domain or in tense marking. Our results also show that it is possible to identify SLI from an early successive bilingual child's performance in one of her two languages. KW - verb morphology KW - tense deficit KW - agreement deficit KW - Turkish-German SLI Y1 - 2012 U6 - https://doi.org/10.1017/S136672891100037X SN - 1366-7289 VL - 15 IS - 1 SP - 39 EP - 57 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Van der Meeren, T. A1 - Mischke, Steffen A1 - Sunjidmaa, N. A1 - Herzschuh, Ulrike A1 - Ito, E. A1 - Martens, K. A1 - Verschuren, Dirk T1 - Subfossil ostracode assemblages from Mongolia quantifying response for paleolimnological applications JF - Ecological indicators : integrating monitoring, assessment and management N2 - Ostracodes (Ostracoda, Crustacea) are aquatic micro-crustaceans with a significant representation in the fossil record. If the environmental influence on the species composition of their communities is robustly quantified, past changes in ostracode communities reflected in fossil assemblages can be used for paleo-environmental reconstruction. We analyzed ostracode assemblages in recently deposited surface sediments from 56 lakes in western and central Mongolia, and simultaneously recorded local water chemistry and solute concentration in order to elucidate the distribution of individual ostracode species in relation to these broad environmental gradients. Multivariate analysis indicated that the species variation in ostracode assemblages could be mainly attributed to variations in percent calcium (%Ca) relative to total cation content, mean annual precipitation, calcium concentration, alkalinity, percent bicarbonate relative to total anion content, and mean July temperature. This matches well with the results of a similar analysis on presence/absence data of living ostracodes in nearshore samples, even though some differences exist between the faunal composition of both datasets. The documented response of ostracode species to environmental variation tracks the typical solute evolutionary pathway for surface waters in this region, characterized by calcite precipitation and consequent depletion in dissolved calcium. Hence, the best quantitative inference model (WA-PLS model with R-jack(2) = 0.70, RMSEP = 0.40) for paleolimnological application was obtained for %Ca. Comparison between this model and a specific conductance (SC) inference model based on the same dataset, and based on ostracode datasets from different regions, indicated that the %Ca inference model suffers less than the SC inference model from a step-change in reconstructed values. The statistical power of different inference models based on Mongolian ostracodes are variously affected by the common dominance of a single euryhaline species (Limnocythere inopinata), limited faunal turnover in the freshwater portion of the salinity gradient, and the bimodal frequency distribution of SC among regional lakes. The latter probably represents true scarcity of lakes with intermediate salinity rather than a biased representation in our dataset. In a broader context of ostracode ecology, and with respect to regional paleolimnological applications, we highlight the potential of fossil Mongolian ostracode assemblages to trace past hydrological shifts associated with changes in groundwater inflow. KW - Ostracoda KW - Inference model KW - Central Asia KW - Paleo-ecology KW - Solute evolution Y1 - 2012 U6 - https://doi.org/10.1016/j.ecolind.2011.07.004 SN - 1470-160X SN - 1872-7034 VL - 14 IS - 1 SP - 138 EP - 151 PB - Elsevier CY - Amsterdam ER - TY - THES A1 - Mettler, Tabea T1 - Study on the dynamics of the Calvin-Benson cycle under different light and CO2 conditions in the green alga Chlamydomonas reinhardtii Y1 - 2012 CY - Potsdam ER - TY - THES A1 - Polyvyanyy, Artem T1 - Structuring process models T1 - Strukturierung von Prozessmodellen N2 - One can fairly adopt the ideas of Donald E. Knuth to conclude that process modeling is both a science and an art. Process modeling does have an aesthetic sense. Similar to composing an opera or writing a novel, process modeling is carried out by humans who undergo creative practices when engineering a process model. Therefore, the very same process can be modeled in a myriad number of ways. Once modeled, processes can be analyzed by employing scientific methods. Usually, process models are formalized as directed graphs, with nodes representing tasks and decisions, and directed arcs describing temporal constraints between the nodes. Common process definition languages, such as Business Process Model and Notation (BPMN) and Event-driven Process Chain (EPC) allow process analysts to define models with arbitrary complex topologies. The absence of structural constraints supports creativity and productivity, as there is no need to force ideas into a limited amount of available structural patterns. Nevertheless, it is often preferable that models follow certain structural rules. A well-known structural property of process models is (well-)structuredness. A process model is (well-)structured if and only if every node with multiple outgoing arcs (a split) has a corresponding node with multiple incoming arcs (a join), and vice versa, such that the set of nodes between the split and the join induces a single-entry-single-exit (SESE) region; otherwise the process model is unstructured. The motivations for well-structured process models are manifold: (i) Well-structured process models are easier to layout for visual representation as their formalizations are planar graphs. (ii) Well-structured process models are easier to comprehend by humans. (iii) Well-structured process models tend to have fewer errors than unstructured ones and it is less probable to introduce new errors when modifying a well-structured process model. (iv) Well-structured process models are better suited for analysis with many existing formal techniques applicable only for well-structured process models. (v) Well-structured process models are better suited for efficient execution and optimization, e.g., when discovering independent regions of a process model that can be executed concurrently. Consequently, there are process modeling languages that encourage well-structured modeling, e.g., Business Process Execution Language (BPEL) and ADEPT. However, the well-structured process modeling implies some limitations: (i) There exist processes that cannot be formalized as well-structured process models. (ii) There exist processes that when formalized as well-structured process models require a considerable duplication of modeling constructs. Rather than expecting well-structured modeling from start, we advocate for the absence of structural constraints when modeling. Afterwards, automated methods can suggest, upon request and whenever possible, alternative formalizations that are "better" structured, preferably well-structured. In this thesis, we study the problem of automatically transforming process models into equivalent well-structured models. The developed transformations are performed under a strong notion of behavioral equivalence which preserves concurrency. The findings are implemented in a tool, which is publicly available. N2 - Im Sinne der Ideen von Donald E. Knuth ist die Prozessmodellierung sowohl Wissenschaft als auch Kunst. Prozessmodellierung hat immer auch eine ästhetische Dimension. Wie das Komponieren einer Oper oder das Schreiben eines Romans, so stellt auch die Prozessmodellierung einen kreativen Akt eines Individuums dar. Somit kann ein Prozess auf unterschiedlichste Weise modelliert werden. Prozessmodelle können anschließend mit wissenschaftlichen Methoden untersucht werden. Prozessmodelle liegen im Regelfall als gerichtete Graphen vor. Knoten stellen Aktivitäten und Entscheidungspunkte dar, während gerichtete Kanten die temporalen Abhängigkeiten zwischen den Knoten beschreiben. Gängige Prozessmodellierungssprachen, zum Beispiel die Business Process Model and Notation (BPMN) und Ereignisgesteuerte Prozessketten (EPK), ermöglichen die Erstellung von Modellen mit einer beliebig komplexen Topologie. Es gibt keine strukturellen Einschränkungen, welche die Kreativität oder Produktivität durch eine begrenzte Anzahl von Modellierungsalternativen einschränken würden. Nichtsdestotrotz ist es oft wünschenswert, dass Modelle bestimmte strukturelle Eigenschaften haben. Ein bekanntes strukturelles Merkmal für Prozessmodelle ist Wohlstrukturiertheit. Ein Prozessmodell ist wohlstrukturiert genau dann, wenn jeder Knoten mit mehreren ausgehenden Kanten (ein Split) einen entsprechenden Knoten mit mehreren eingehenden Kanten (einen Join) hat, und umgekehrt, so dass die Knoten welche zwischen dem Split und dem Join liegen eine single-entry-single-exit (SESE) Region bilden. Ist dies nicht der Fall, so ist das Modell unstrukturiert. Wohlstrukturiertheit ist aufgrund einer Vielzahl von Gründen wünschenswert: (i) Wohlstrukturierte Modelle sind einfacher auszurichten, wenn sie visualisiert werden, da sie planaren Graphen entsprechen. (ii) Wohlstrukturierte Modelle zeichnen sich durch eine höhere Verständlichkeit aus. (iii) Wohlstrukturierte Modelle haben oft weniger Fehler als unstrukturierte Modelle. Auch ist die Wahrscheinlichkeit fehlerhafter Änderungen größer, wenn Modelle unstrukturiert sind. (iv) Wohlstrukturierte Modelle eignen sich besser für die formale Analyse, da viele Techniken nur für wohlstrukturierte Modelle anwendbar sind. (v) Wohlstrukturierte Modelle sind eher für die effiziente Ausführung und Optimierung geeignet, z.B. wenn unabhängige Regionen eines Prozesses für die parallele Ausführung identifiziert werden. Folglich gibt es eine Reihe von Prozessmodellierungssprachen, z.B. die Business Process Execution Language (BPEL) und ADEPT, welche den Modellierer anhalten nur wohlstrukturierte Modelle zu erstellen. Solch wohlstrukturiertes Modellieren impliziert jedoch gewisse Einschränkungen: (i) Es gibt Prozesse, welche nicht mittels wohlstrukturierten Prozessmodellen dargestellt werden können. (ii) Es gibt Prozesse, für welche die wohlstrukturierte Modellierung mit einer erheblichen Vervielfältigung von Modellierungs-konstrukten einhergeht. Aus diesem Grund vertritt diese Arbeit den Standpunkt, dass ohne strukturelle Einschränkungen modelliert werden sollte, anstatt Wohlstrukturiertheit von Beginn an zu verlangen. Anschließend können, sofern gewünscht und wo immer es möglich ist, automatische Methoden Modellierungsalternativen vorschlagen, welche "besser" strukturiert sind, im Idealfall sogar wohlstrukturiert. Die vorliegende Arbeit widmet sich dem Problem der automatischen Transformation von Prozessmodellen in verhaltensäquivalente wohlstrukturierte Prozessmodelle. Die vorgestellten Transformationen erhalten ein strenges Verhaltensequivalenzkriterium, welches die Parallelität wahrt. Die Resultate sind in einem frei verfügbaren Forschungsprototyp implementiert worden. KW - Strukturierung KW - Wohlstrukturiertheit KW - Prozesse KW - Verhalten KW - Modellierung KW - Structuring KW - Well-structuredness KW - Process KW - Behavior KW - Modeling Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-59024 ER - TY - JOUR A1 - Polyvyanyy, Artem A1 - Garcia-Banuelos, Luciano A1 - Dumas, Marlon T1 - Structuring acyclic process models JF - Information systems N2 - This article studies the problem of transforming a process model with an arbitrary topology into an equivalent well-structured process model. While this problem has received significant attention, there is still no full characterization of the class of unstructured process models that can be transformed into well-structured ones, nor an automated method for structuring any process model that belongs to this class. This article fills this gap in the context of acyclic process models. The article defines a necessary and sufficient condition for an unstructured acyclic process model to have an equivalent well-structured process model under fully concurrent bisimulation, as well as a complete structuring method. The method has been implemented as a tool that takes process models captured in the BPMN and EPC notations as input. The article also reports on an empirical evaluation of the structuring method using a repository of process models from commercial practice. KW - Process modeling KW - Structured modeling KW - Structuring KW - Model equivalence KW - Petri net unfolding KW - Modular decomposition Y1 - 2012 U6 - https://doi.org/10.1016/j.is.2011.10.005 SN - 0306-4379 VL - 37 IS - 6 SP - 518 EP - 538 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Seto, Jong A1 - Ma, Yurong A1 - Davis, Sean A. A1 - Meldrum, Fiona A1 - Gourrier, Aurelien A1 - Kim, Yi-Yeoun A1 - Schilde, Uwe A1 - Sztucki, Michael A1 - Burghammer, Manfred A1 - Maltsev, Sergey A1 - Jäger, Christian A1 - Cölfen, Helmut T1 - Structure-property relationships of a biological mesocrystal in the adult sea urchin spine JF - Proceedings of the National Academy of Sciences of the United States of America N2 - Structuring overmany length scales is a design strategy widely used in Nature to create materials with unique functional properties. We here present a comprehensive analysis of an adult sea urchin spine, and in revealing a complex, hierarchical structure, showhow Nature fabricates a material which diffracts as a single crystal of calcite and yet fractures as a glassy material. Each spine comprises a highly oriented array of Mg-calcite nanocrystals in which amorphous regions and macromolecules are embedded. It is postulated that this mesocrystalline structure forms via the crystallization of a dense array of amorphous calcium carbonate (ACC) precursor particles. A residual surface layer of ACC and/or macromolecules remains around the nanoparticle units which creates the mesocrystal structure and contributes to the conchoidal fracture behavior. Nature's demonstration of howcrystallization of an amorphous precursor phase can create a crystalline material with remarkable properties therefore provides inspiration for a novel approach to the design and synthesis of synthetic composite materials. KW - calcium carbonate biomineralization KW - echinoderm skeleton KW - hierarchical structuring KW - mesocrystal KW - skeletal elements Y1 - 2012 U6 - https://doi.org/10.1073/pnas.1109243109 SN - 0027-8424 VL - 109 IS - 10 SP - 3699 EP - 3704 PB - National Acad. of Sciences CY - Washington ER - TY - JOUR A1 - Collings, R. A1 - Lange, Dietrich A1 - Rietbrock, Andreas A1 - Tilmann, F. A1 - Natawidjaja, D. A1 - Suwargadi, B. A1 - Miller, M. A1 - Saul, Joschim T1 - Structure and seismogenic properties of the Mentawai segment of the Sumatra subduction zone revealed by local earthquake traveltime tomography JF - Journal of geophysical research : Solid earth N2 - On 12 September 2007, an M-w 8.4 earthquake occurred within the southern section of the Mentawai segment of the Sumatra subduction zone, where the subduction thrust had previously ruptured in 1833 and 1797. Traveltime data obtained from a temporary local seismic network, deployed between December 2007 and October 2008 to record the aftershocks of the 2007 event, was used to determine two-dimensional (2-D) and three-dimensional (3-D) velocity models of the Mentawai segment. The seismicity distribution reveals significant activity along the subduction interface and within two clusters in the overriding plate either side of the forearc basin. The downgoing slab is clearly distinguished by a dipping region of high Vp (8.0 km/s), which can be a traced to similar to 50 km depth, with an increased Vp/Vs ratio (1.75 to 1.90) beneath the islands and the western side of the forearc basin, suggesting hydrated oceanic crust. Above the slab, a shallow continental Moho of less than 30 km depth can be inferred, suggesting that the intersection of the continental mantle with the subducting slab is much shallower than the downdip limit of the seismogenic zone despite localized serpentinization being present at the toe of the mantle wedge. The outer arc islands are characterized by low Vp (4.5-5.8 km/s) and high Vp/Vs (greater than 2.0), suggesting that they consist of fluid saturated sediments. The very low rigidity of the outer forearc contributed to the slow rupture of the M-w 7.7 Mentawai tsunami earthquake on 25 October 2010. Y1 - 2012 U6 - https://doi.org/10.1029/2011JB008469 SN - 2169-9313 SN - 2169-9356 VL - 117 IS - 3 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - de Molina, Paula Malo A1 - Herfurth, Christoph A1 - Laschewsky, André A1 - Gradzielski, Michael T1 - Structure and dynamics of networks in mixtures of hydrophobically modified telechelic multiarm polymers and oil in water microemulsions JF - Langmuir N2 - The structural and dynamical properties of oil-in-water (O/W) microemulsions (MEs) modified with telechelic polymers of different functionality (e.g., number of hydrophobically modified arms, f) were studied by means of dynamic light scattering (DLS), small-angle neutron scattering (SANS), and high frequency rheology measurements as a function of the polymer architecture and the amount of added polymer. For this purpose, we employed tailor-made hydrophobically end-capped poly(N,N-dimethylacrylamide) star polymers of a variable number of endcaps, f, of different alkyl chain lengths, synthesized by the reversible addition-fragmentation chain transfer method. The addition of the different end-capped polymers to an uncharged ME of O/W droplets leads to a large enhancement of the viscosity of the systems. SANS experiments show that the O/W ME droplets are not changed upon the addition of the polymer, and its presence only changes the interdroplet interactions. The viscosity increases largely upon addition of a polymer, and this enhancement depends pronouncedly on the alkyl length of the hydrophobic sticker as it controls the residence time in a ME droplet. Similarly, the high frequency modulus G(0) depends on the amount of added polymer but not on the sticker length. G(0) was found to be directly proportional to f - 1. The onset of network formation is shifted to a lower number of stickers per ME droplet with increasing f, and the network formation becomes more effective. Thus, the dynamics of network formation are controlled by the polymer architecture. The effect on the dynamics seen by DLS is even more pronounced. Upon increasing the polymer concentration, slower relaxation modes appear that become especially pronounced with increasing number of arms. The relaxation dynamics are correlated to the rheological relaxation, and both are controlled by the polymer architecture. Y1 - 2012 U6 - https://doi.org/10.1021/la303673a SN - 0743-7463 VL - 28 IS - 45 SP - 15994 EP - 16006 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Shainyan, Bagrat A. A1 - Kirpichenko, Svetlana V. A1 - Shlykov, Sergei A. A1 - Keinpeter, Erich T1 - Structure and conformational properties of 1,3,3-Trimethyl-1,3-Azasilinane gas electron diffraction, dynamic NMR, and theoretical study JF - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory N2 - Structure and the conformational properties of 1,3,3-trimethyl-1,3-azasilinane have been studied. According to gas electron diffraction (GED), the molecule exists in a slightly distorted chair conformation with the N-Me group in equatorial position. High-level quantum chemical calculations excellently, reproduce the experimental geometry. Employing variable temperature H-1 and C-13 NMR spectroscopy down to 103 K, the conformational equilibrium could be frozen and the barrier to ring inversion determined. Y1 - 2012 U6 - https://doi.org/10.1021/jp2110852 SN - 1089-5639 VL - 116 IS - 1 SP - 784 EP - 789 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Shainyan, Bagrat A. A1 - Kirpichenko, Svetlana V. A1 - Shlykov, Sergei A. T1 - Structure and Conformational Properties of 1,3,3-Trimethyl-1,3-Azasilinane : Gas Electron Diffraction, Dynamic NMR, and Theoretical Study. Y1 - 2012 SN - 1089-5639 ER - TY - JOUR A1 - Kreye, Oliver A1 - Türünc, Oguz A1 - Sehlinger, Ansgar A1 - Rackwitz, Jenny A1 - Meier, Michael A. R. T1 - Structurally diverse polyamides obtained from monomers derived via the Ugi multicomponent reaction JF - Chemistry - a European journal N2 - The combination of the Ugi four-component reaction (Ugi-4CR) with acyclic diene metathesis (ADMET) or thiolene polymerization led to the formation of poly-1-(alkylcarbamoyl) carboxamides, a new class of substituted polyamides with amide moieties in the polymer backbone, as well as its side chains. 10-Undecenoic acid, obtained by pyrolysis of ricinoleic acid, the main fatty acid of castor oil, was used as the key renewable building block. The use of different primary amines, as well as isonitriles (isocyanides) for the described Ugi reactions provided monomers with high structural diversity. Furthermore, the possibility of versatile post-modification of functional groups in the side chains of the corresponding polymers should be of considerable interest in materials science. The obtained monomers were polymerized by ADMET, as well as thiolene, chemistry and all polymers were fully characterized. Finally, ortho-nitrobenzylamide-containing polyamides obtained by this route were shown to be photoresponsive and exhibited a dramatic change of their properties upon irradiation with light. KW - metathesis KW - polyamides KW - polymerization KW - renewable resources KW - Ugi reaction KW - thiol-ene reactions Y1 - 2012 U6 - https://doi.org/10.1002/chem.201103341 SN - 0947-6539 VL - 18 IS - 18 SP - 5767 EP - 5776 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Zaccheus, Mona V. A1 - Bröker, Nina Kristin A1 - Lundborg, Magnus A1 - Uetrecht, Charlotte A1 - Barbirz, Stefanie A1 - Widmalm, Goran T1 - Structural studies of the O-antigen polysaccharide from Escherichia coli TD2158 having O18 serogroup specificity and aspects of its interaction with the tailspike endoglycosidase of the infecting bacteriophage HK620 JF - Carbohydrate research N2 - We have analyzed the O-antigen polysaccharide of the previously uncharacterized Escherichia coli strain TD2158 which is a host of bacteriophage HK620. This bacteriophage recognizes and cleaves the polysaccharide with its tailspike protein (TSP). The polysaccharide preparation as well as oligosaccharides obtained from HK620TSP endoglycosidase digests were analyzed with NMR spectroscopy. Additionally, sugar analysis was performed on the O-antigen polysaccharide and MALDI-TOF MS was used in oligosaccharide analysis. The present study revealed a heterogeneous polysaccharide with a hexasaccharide repeating unit of the following structure: alpha-D-Glcp-(1 -> 6) vertical bar vertical bar 2)-alpha-L-Rhap-(1 -> 6)-alpha-D-Glcp-(1 -> 4)-alpha-D-Galp-(1 -> 3)-alpha-D-GlcpNAc- (1 ->vertical bar beta-D-Glcp/beta-D-GlcpNAc-(1 -> 3) A repeating unit with a D-GlcNAc substitution of D-Gal has been described earlier as characteristic for serogroup O18A1. Accordingly, we termed repeating units with D-Glc substitution at D-Gal as O18A2. NMR analyses of the polysaccharide confirmed that O18A1- and O18A2-type repeats were present in a 1:1 ratio. However, HK620TSP preferentially bound the D-GlcNAc- substituted O18A1-type repeating units in its high affinity binding pocket with a dissociation constant of 140 mu M and disfavored the O18A2-type having a beta-D-Glcp-(1 -> 3)-linked group. As a result, in hexasaccharide preparations, O18A1 and O18A2 repeats were present in a 9: 1 ratio stressing the clear preference of O18A1- type repeats to be cleaved by HK620TSP. KW - Escherichia coli KW - Tailspike KW - Endoglycosidase KW - Lipopolysaccharide KW - NMR KW - Mass spectrometry Y1 - 2012 U6 - https://doi.org/10.1016/j.carres.2012.05.022 SN - 0008-6215 VL - 357 IS - 8 SP - 118 EP - 125 PB - Elsevier CY - Oxford ER - TY - THES A1 - Herzog, Marc T1 - Structural dynamics of photoexcited nanolayered perovskites studied by ultrafast x-ray diffraction T1 - Untersuchung der Strukturdynamik photoangeregter Nanoschicht-Perowskite mittels ultraschneller Röntgenbeugung N2 - This publication-based thesis represents a contribution to the active research field of ultrafast structural dynamics in laser-excited nanostructures. The investigation of such dynamics is mandatory for the understanding of the various physical processes on microscopic scales in complex materials which have great potentials for advances in many technological applications. I theoretically and experimentally examine the coherent, incoherent and anharmonic lattice dynamics of epitaxial metal-insulator heterostructures on timescales ranging from femtoseconds up to nanoseconds. To infer information on the transient dynamics in the photoexcited crystal lattices experimental techniques using ultrashort optical and x-ray pulses are employed. The experimental setups include table-top sources as well as large-scale facilities such as synchrotron sources. At the core of my work lies the development of a linear-chain model to simulate and analyze the photoexcited atomic-scale dynamics. The calculated strain fields are then used to simulate the optical and x-ray response of the considered thin films and multilayers in order to relate the experimental signatures to particular structural processes. This way one obtains insight into the rich lattice dynamics exhibiting coherent transport of vibrational energy from local excitations via delocalized phonon modes of the samples. The complex deformations in tailored multilayers are identified to give rise to highly nonlinear x-ray diffraction responses due to transient interference effects. The understanding of such effects and the ability to precisely calculate those are exploited for the design of novel ultrafast x-ray optics. In particular, I present several Phonon Bragg Switch concepts to efficiently generate ultrashort x-ray pulses for time-resolved structural investigations. By extension of the numerical models to include incoherent phonon propagation and anharmonic lattice potentials I present a new view on the fundamental research topics of nanoscale thermal transport and anharmonic phonon-phonon interactions such as nonlinear sound propagation and phonon damping. The former issue is exemplified by the time-resolved heat conduction from thin SrRuO3 films into a SrTiO3 substrate which exhibits an unexpectedly slow heat conductivity. Furthermore, I discuss various experiments which can be well reproduced by the versatile numerical models and thus evidence strong lattice anharmonicities in the perovskite oxide SrTiO3. The thesis also presents several advances of experimental techniques such as time-resolved phonon spectroscopy with optical and x-ray photons as well as concepts for the implementation of x-ray diffraction setups at standard synchrotron beamlines with largely improved time-resolution for investigations of ultrafast structural processes. This work forms the basis for ongoing research topics in complex oxide materials including electronic correlations and phase transitions related to the elastic, magnetic and polarization degrees of freedom. N2 - Diese publikationsbasierte Dissertation ist ein Beitrag zu dem aktuellen Forschungsgebiet der ultraschnellen Strukturdynamik in laserangeregten Nanostrukturen. Die Erforschung solcher Vorgänge ist unabdingbar für ein Verständnis der vielseitigen physikalischen Prozesse auf mikroskopischen Längenskalen in komplexen Materialien, welche enorme Weiterentwicklungen für technologische Anwendungen versprechen. Meine theoretischen und experimentellen Untersuchungen betrachten kohärente, inkohärente und anharmonische Gitterdynamiken in epitaktischen Metal-Isolator-Heterostrukturen auf Zeitskalen von Femtosekunden bis Nanosekunden. Um Einsichten in solche transienten Prozesse in laserangeregten Kristallen zu erhalten, werden experimentelle Techniken herangezogen, die ultrakurze Pulse von sichtbarem Licht und Röntgenstrahlung verwenden. Ein zentraler Bestandteil meiner Arbeit ist die Entwicklung eines Linearkettenmodells zur Simulation und Analyse der laserinitiierten Atombewegungen. Die damit errechneten Verzerrungsfelder werden anschließend verwendet, um die Änderung der optischen und Röntgeneigenschaften der betrachteten Dünnfilm- und Vielschichtsysteme zu simulieren. Diese Rechnungen werden dann mit den experimentellen Daten verglichen, um die experimentellen Signaturen mit errechneten strukturellen Prozessen zu identifizieren. Dadurch erhält man Einsicht in die vielseitige Gitterdynamiken, was z.B. einen kohärenten Transport der Vibrationsenergie von lokal angeregten Bereichen durch delokalisierte Phononenmoden offenbart. Es wird gezeigt, dass die komplexen Deformationen in maßgeschneiderten Vielschichtsystemen hochgradig nichtlineare Röntgenbeugungseffekte auf Grund von transienten Interferenzerscheinungen verursachen. Das Verständnis dieser Prozesse und die Möglichkeit, diese präzise zu simulieren, werden dazu verwendet, neuartige ultraschnelle Röntgenoptiken zu entwerfen. Insbesondere erläutere ich mehrere Phonon-Bragg-Schalter-Konzepte für die effiziente Erzeugung ultrakurzer Röntgenpulse, die in zeitaufgelösten Strukturanalysen Anwendung finden. Auf Grund der Erweiterung der numerischen Modelle zur Beschreibung von inkohärenter Phononenausbreitung und anharmonischer Gitterpotentiale decken diese ebenfalls die aktuellen Themengebiete von Wärmetransport auf Nanoskalen und anharmonischer Phonon-Phonon-Wechselwirkung (z.B. nichtlineare Schallausbreitung und Phononendämpfung) ab. Die erstere Thematik wird am Beispiel der zeitaufgelösten Wärmeleitung von einem dünnen SrRuO3-Film in ein SrTiO3-Substrat behandelt, wobei ein unerwartet langsamer Wärmetransport zu Tage tritt. Außerdem diskutiere ich mehrere Experimente, die auf Grund der sehr guten Reproduzierbarkeit durch die numerischen Modelle starke Gitteranharmonizitäten in dem oxidischen Perowskit SrTiO3 bezeugen. Diese Dissertation erarbeitet zusätzlich verschiedene Weiterentwicklungen von experimentellen Methoden, wie z.B. die zeitaufgelöste Phononenspektroskopie mittels optischer Photonen und Röntgenphotonen, sowie Konzepte für die Umsetzung von Röntgenbeugungsexperimenten an Standard-Synchrotronquellen mit stark verbesserter Zeitauflösung für weitere Studien von ultraschnellen Strukturvorgängen. KW - ultraschnelle Röntgenbeugung KW - Phononen KW - epitaktisch KW - ultrafast x-ray diffraction KW - phonons KW - epitaxial Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-62632 ER - TY - JOUR A1 - Gemeinholzer, B. A1 - May, F. A1 - Ristow, Michael A1 - Batsch, C. A1 - Lauterbach, D. T1 - Strong genetic differentiation on a fragmentation gradient among populations of the heterocarpic annual Catananche lutea L. (Asteraceae) JF - Plant systematics and evolution N2 - In landscapes which are predominately characterised by agriculture, natural ecosystems are often reduced to a mosaic of scattered patches of natural vegetation. Species with formerly connected distribution ranges now have restricted gene flow among populations. This has isolating effects upon population structure, because species are often confined by their limited dispersal capabilities. In this study, we test the effects of habitat fragmentation, precipitation, and isolation of populations on the genetic structure (AFLP) and fitness of the Asteraceae Catananche lutea. Our study area is an agro-dominated ecosystem in the desert-Mediterranean transition zone of the Southern Judea Lowlands in Israel. Our analysis revealed an intermediate level of intra-population genetic diversity across the study site with reduced genetic diversity on smaller scale. Although the size of the whole study area was relatively small (20 x 45 km), we found isolation by distance to be effective. We detected a high level of genetic differentiation among populations but genetic structure did not reflect spatial patterns. Population genetic diversity was correlated neither with position along the precipitation gradient nor with different seed types or other plant fitness variables in C. lutea. KW - AFLP KW - Heterocarpy KW - Population structure KW - Precipitation gradient KW - Asteraceae Y1 - 2012 U6 - https://doi.org/10.1007/s00606-012-0661-1 SN - 0378-2697 VL - 298 IS - 8 SP - 1585 EP - 1596 PB - Springer CY - Wien ER - TY - JOUR A1 - König, Tobias A1 - Santer, Svetlana T1 - Stretching and distortion of a photosensitive polymer film by surface plasmon generated near fields in the vicinity of a nanometer sized metal pin hole JF - Nanotechnology N2 - Here we demonstrate how a surface plasmon (SP) generated near field pattern in the vicinity of a nano-scale pin hole can be used to generate reversible topography changes in a photosensitive polymer film above the opening. This can be achieved by simply changing the polarization state of the plasmon generating incoming light. In the case of linear polarization, the near field intensity pattern causes the film to laterally expand/contract according to the direction of the polarization. For circular polarization, two pronounced rims corresponding to maxima in the topography are observed. In all cases, the topographical variation is in close agreement with the SP intensity distribution computed from finite difference time domain simulation. Our results demonstrate the versatility of using SP near fields to imprint a variety of structures into photosensitive polymer films using only a single metallic mask. Y1 - 2012 U6 - https://doi.org/10.1088/0957-4484/23/15/155301 SN - 0957-4484 VL - 23 IS - 15 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Wang, Lifeng A1 - Hainzl, Sebastian A1 - Zöller, Gert A1 - Holschneider, Matthias T1 - Stress- and aftershock-constrained joint inversions for coseismic and postseismic slip applied to the 2004 M6.0 Parkfield earthquake JF - Journal of geophysical research : Solid earth N2 - Both aftershocks and geodetically measured postseismic displacements are important markers of the stress relaxation process following large earthquakes. Postseismic displacements can be related to creep-like relaxation in the vicinity of the coseismic rupture by means of inversion methods. However, the results of slip inversions are typically non-unique and subject to large uncertainties. Therefore, we explore the possibility to improve inversions by mechanical constraints. In particular, we take into account the physical understanding that postseismic deformation is stress-driven, and occurs in the coseismically stressed zone. We do joint inversions for coseismic and postseismic slip in a Bayesian framework in the case of the 2004 M6.0 Parkfield earthquake. We perform a number of inversions with different constraints, and calculate their statistical significance. According to information criteria, the best result is preferably related to a physically reasonable model constrained by the stress-condition (namely postseismic creep is driven by coseismic stress) and the condition that coseismic slip and large aftershocks are disjunct. This model explains 97% of the coseismic displacements and 91% of the postseismic displacements during day 1-5 following the Parkfield event, respectively. It indicates that the major postseismic deformation can be generally explained by a stress relaxation process for the Parkfield case. This result also indicates that the data to constrain the coseismic slip model could be enriched postseismically. For the 2004 Parkfield event, we additionally observe asymmetric relaxation process at the two sides of the fault, which can be explained by material contrast ratio across the fault of similar to 1.15 in seismic velocity. Y1 - 2012 U6 - https://doi.org/10.1029/2011JB009017 SN - 2169-9313 SN - 2169-9356 VL - 117 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Domahs, Ulrike A1 - Knaus, Johannes A1 - Orzechowska, Paula A1 - Wiese, Richard T1 - Stress "deafness" in a language with fixed word stress an ERR study on Polish JF - Frontiers in psychology N2 - The aim of the present contribution was to examine the factors influencing the prosodic processing in a language with predictable word stress. For Polish, a language with fixed penultimate stress but several well-defined exceptions, difficulties in the processing and representation of prosodic information have been reported (e.g., Peperkamp and Dupoux, 2002). The present study utilized event-related potentials (ERPs) to investigate the factors influencing prosodic processing in Polish. These factors are (i) the predictability of stress and (ii) the prosodic structure in terms of metrical feet. Polish native speakers were presented with correctly and incorrectly stressed Polish words and instructed to judge the correctness of the perceived stress patterns. For some stress violations, an early negativity was found which was interpreted as a reflection of an error-detection mechanism. In addition, exceptional stress patterns (=antepenultimate stress) and post-lexical (=initial) stress evoked a task-related positivity effect (P300) whose amplitude and latency is correlated with the degree of anomaly and deviation from an expectation. In contrast, violations involving the default (=penultimate stress) did not produce such an effect. This asymmetrical result is interpreted to reflect that Polish native speakers are less sensitive to the default pattern than to the exceptional or post-lexical patterns. Behavioral results are orthogonal to the electrophysiological results showing that Polish speakers had difficulties to reject any kind of stress violation. Thus, on a meta-linguistic level Polish speakers appeared to be stress-"deaf" for any kind of stress manipulation, whereas the neural reactions differentiate between the default and lexicalized patterns. KW - stress "deafness" KW - fixed stress system KW - prosodic representation KW - P300 KW - generalized error-detection mechanism Y1 - 2012 U6 - https://doi.org/10.3389/fpsyg.2012.00439 SN - 1664-1078 VL - 3 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Szymanski, Kolja V. A1 - Tönnies, Mario A1 - Becher, Anne A1 - Fatykhova, Diana A1 - N'Guessan, Philippe D. A1 - Gutbier, Birgitt A1 - Klauschen, Frederick A1 - Neuschäfer-Rube, Frank A1 - Schneider, Paul A1 - Rückert, Jens A1 - Neudecker, Jens A1 - Bauer, Torsten T. A1 - Dalhoff, Klaus A1 - Droemann, Daniel A1 - Gruber, Achim D. A1 - Kershaw, Olivia A1 - Temmesfeld-Wollbrueck, Bettina A1 - Suttorp, Norbert A1 - Hippenstiel, Stefan A1 - Hocke, Andreas C. T1 - Streptococcus pneumoniae-induced regulation of cyclooxygenase-2 in human lung tissue JF - The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology N2 - The majority of cases of community-acquired pneumonia are caused by Streptococcus pneumoniae and most studies on pneumococcal host interaction are based on cell culture or animal experiments. Thus, little is known about infections in human lung tissue. Cyclooxygenase-2 and its metabolites play an important regulatory role in lung inflammation. Therefore, we established a pneumococcal infection model on human lung tissue demonstrating mitogen-activated protein kinase (MAPK)-dependent induction of cyclooxygenase-2 and its related metabolites. In addition to alveolar macrophages and the vascular endothelium, cyclooxygenase-2 was upregulated in alveolar type II but not type I epithelial cells, which was confirmed in lungs of patients suffering from acute pneumonia. Moreover, we demonstrated the expression profile of all four E prostanoid receptors at the mRNA level and showed functionality of the E prostanoid(4) receptor by cyclic adenosine monophosphate production. Additionally, in comparison to previous studies, cyclooxygenase-2/prostaglandin E-2 related pro- and anti-inflammatory mediator regulation was partly confirmed in human lung tissue after pneumococcal infection. Overall, cell type-specific and MAPK-dependent cyclooxygenase-2 expression and prostaglandin E-2 formation in human lung tissue may play an important role in the early phase of pneumococcal infections. KW - Alveolar epithelial cells KW - cytokines KW - inflammation KW - lung infection KW - pneumonia KW - prostaglandins Y1 - 2012 U6 - https://doi.org/10.1183/09031936.00186911 SN - 0903-1936 VL - 40 IS - 6 SP - 1458 EP - 1467 PB - European Respiratory Society CY - Sheffield ER - TY - JOUR A1 - Naafs, B. David A. A1 - Hefter, Jens A1 - Acton, Gary A1 - Haug, Gerald H. A1 - Martinez-Garcia, Alfredo A1 - Pancost, Richard A1 - Stein, Rüdiger T1 - Strengthening of North American dust sources during the late Pliocene (2.7 Ma) JF - Earth & planetary science letters N2 - Here we present orbitally-resolved records of terrestrial higher plant leaf wax input to the North Atlantic over the last 3.5 Ma, based on the accumulation of long-chain n-alkanes and n-alkanl-1-ols at IODP Site U1313. These lipids are a major component of dust, even in remote ocean areas, and have a predominantly aeolian origin in distal marine sediments. Our results demonstrate that around 2.7 million years ago (Ma), coinciding with the intensification of the Northern Hemisphere glaciation (NHG), the aeolian input of terrestrial material to the North Atlantic increased drastically. Since then, during every glacial the aeolian input of higher plant material was up to 30 times higher than during interglacials. The close correspondence between aeolian input to the North Atlantic and other dust records indicates a globally uniform response of dust sources to Quaternary climate variability, although the amplitude of variation differs among areas. We argue that the increased aeolian input at Site U1313 during glacials is predominantly related to the episodic appearance of continental ice sheets in North America and the associated strengthening of glaciogenic dust sources. Evolutional spectral analyses of the n-alkane records were therefore used to determine the dominant astronomical forcing in North American ice sheet advances. These results demonstrate that during the early Pleistocene North American ice sheet dynamics responded predominantly to variations in obliquity (41 ka), which argues against previous suggestions of precession-related variations in Northern Hemisphere ice sheets during the early Pleistocene. KW - aeolian input KW - dust KW - terrestrial higher plant waxes KW - Milankovitch KW - North Atlantic KW - Quaternary Y1 - 2012 U6 - https://doi.org/10.1016/j.epsl.2011.11.026 SN - 0012-821X SN - 1385-013X VL - 317 SP - 8 EP - 19 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Mohr, Christian Heinrich A1 - Montgomery, David R. A1 - Huber, Anton A1 - Bronstert, Axel A1 - Iroume, Andres T1 - Streamflow response in small upland catchments in the Chilean coastal range to the M-W 8.8 Maule earthquake on 27 February 2010 JF - Journal of geophysical research : Earth surface N2 - Hydrological response to earthquakes has long been observed, yet the mechanisms responsible still remain unclear and likely vary in space and time. This study explores the base flow response in small upland catchments of the Coastal Range of south-central Chile after the M-W 8.8 Maule earthquake of 27 February 2010. An initial decline in streamflow followed by an increase of up to 400% of the discharge measured immediately before the earthquake occurred, and diurnal streamflow oscillations intensified after the earthquake. Neither response time, nor time to maximum streamflow discharge showed any relationship with catchment topography or size, suggesting non-uniform release of water across the catchments. The fast response, unaffected stream water temperatures and a simple diffusion model point to the sandy saprolite as the source of the excess water. Base flow recession analysis reveals no evidence for substantial enhancement of lateral hydraulic conductivity in the saprolite after the earthquake. Seismic energy density reached similar to 170 J/m(3) for the main shock and similar to 0.9 J/m(3) for the aftershock, exceeding the threshold for liquefaction by undrained consolidation only during the main shock. Although increased hydraulic gradient due to ground acceleration-triggered, undrained consolidation is consistent with empirical magnitude-distance relationships for liquefaction, the lack of independent evidence for liquefaction means that enhanced vertical permeability (probably in combination with co-seismic near-surface dilatancy) cannot be excluded as a potential mechanism. Undrained consolidation may have released additional water from the saturated saprolite into the overlying soil, temporarily reducing water transfer to the creeks but enlarging the cross-section of the saturated zone, which in turn enhanced streamflow after establishment of a new hydraulic equilibrium. The enlarged saturated zone facilitated water uptake by roots and intensified evapotranspiration. Y1 - 2012 U6 - https://doi.org/10.1029/2011JF002138 SN - 0148-0227 VL - 117 IS - 23 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Heger, Tobias A1 - Rohrbeck, Rene T1 - Strategic foresight for collaborative exploration of new business fields JF - Technological forecasting & social change N2 - To ensure long-term competitiveness, companies need to develop the ability to explore, plan, and develop new business fields. A suitable approach faces multiple challenges because it needs to (1) integrate multiple perspectives, (2) ensure a high level of participation of the major stakeholders and decision-makers, (3) function despite a high level of uncertainty, and (4) take into account interdependencies between the influencing factors. In this paper, we present an integrated approach that combines multiple strategic-foresight methods in a synergetic way. It was applied in an inter-organizational business field exploration project in the telecommunications industry. KW - Strategic foresight KW - Business field exploration KW - Innovation management KW - Open innovation Y1 - 2012 U6 - https://doi.org/10.1016/j.techfore.2011.11.003 SN - 0040-1625 VL - 79 IS - 5 SP - 819 EP - 831 PB - Elsevier CY - New York ER - TY - JOUR A1 - Barkai, Eli A1 - Garini, Yuval A1 - Metzler, Ralf T1 - Strange Kinetics of single molecules in living cells JF - Physics today Y1 - 2012 SN - 0031-9228 VL - 65 IS - 8 SP - 29 EP - 35 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Larhlimi, Abdelhalim A1 - Basler, Georg A1 - Grimbs, Sergio A1 - Selbig, Joachim A1 - Nikoloski, Zoran T1 - Stoichiometric capacitance reveals the theoretical capabilities of metabolic networks JF - Bioinformatics N2 - Motivation: Metabolic engineering aims at modulating the capabilities of metabolic networks by changing the activity of biochemical reactions. The existing constraint-based approaches for metabolic engineering have proven useful, but are limited only to reactions catalogued in various pathway databases. Results: We consider the alternative of designing synthetic strategies which can be used not only to characterize the maximum theoretically possible product yield but also to engineer networks with optimal conversion capability by using a suitable biochemically feasible reaction called 'stoichiometric capacitance'. In addition, we provide a theoretical solution for decomposing a given stoichiometric capacitance over a set of known enzymatic reactions. We determine the stoichiometric capacitance for genome-scale metabolic networks of 10 organisms from different kingdoms of life and examine its implications for the alterations in flux variability patterns. Our empirical findings suggest that the theoretical capacity of metabolic networks comes at a cost of dramatic system's changes. Y1 - 2012 U6 - https://doi.org/10.1093/bioinformatics/bts381 SN - 1367-4803 VL - 28 IS - 18 SP - I502 EP - I508 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Zenichowski, Karl A1 - Nacci, Ch A1 - Fölsch, S. A1 - Dokic, Jadranka A1 - Klamroth, Tillmann A1 - Saalfrank, Peter T1 - STM-switching of organic molecules on semiconductor surfaces: an above threshold density matrix model for 1,5 cyclooctadiene on Si(100) JF - Journal of physics : Condensed matter N2 - The scanning tunnelling microscope (STM)-induced switching of a single cyclooctadiene molecule between two stable conformations chemisorbed on a Si(100) surface is investigated using an above threshold model including a neutral ground state and an ionic excited state potential. Switching was recently achieved experimentally with an STM operated at cryogenic temperatures (Nacci et al 2008 Phys. Rev. B 77 121405(R)) and rationalized by a below threshold model using just a single potential energy surface (Nacci et al 2009 Nano Lett. 9 2997). In the present paper, we show that experimental key findings on the inelastic electron tunnelling (IET) switching can also be rationalized using an above threshold density matrix model, which includes, in addition to the neutral ground state potential, an anionic or cationic excited potential. We use one and two-dimensional potential energy surfaces. Furthermore, the influence of two key parameters of the density matrix description, namely the electronic lifetime of the ionic resonance and the vibrational lifetimes, on the ground state potential are discussed. Y1 - 2012 U6 - https://doi.org/10.1088/0953-8984/24/39/394009 SN - 0953-8984 VL - 24 IS - 39 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Dambacher, Michael A1 - Dimigen, Olaf A1 - Braun, Mario A1 - Wille, Kristin A1 - Jacobs, Arthur M. A1 - Kliegl, Reinhold T1 - Stimulus onset asynchrony and the timeline of word recognition: Event-related potentials during sentence reading JF - Neuropsychologia : an international journal in behavioural and cognitive neuroscience N2 - Three ERP experiments examined the effect of word presentation rate (i.e., stimulus onset asynchrony, SOA) on the time course of word frequency and predictability effects in sentence reading. In Experiments 1 and 2, sentences were presented word-by-word in the screen center at an SOA of 700 and 490 ms, respectively. While these rates are typical for psycholinguistic ERP research, natural reading happens at a considerably faster pace. Accordingly. Experiment 3 employed a near-normal SOA of 280 ms, which approximated the rate of normal reading. Main results can be summarized as follows: (1) The onset latency of early frequency effects decreases gradually with increasing presentation rates. (2) An early interaction between top-down and bottom-up processing is observed only under a near-normal SOA. (3) N400 predictability effects occur later and are smaller at a near-normal (i.e., high) presentation rate than at the lower rates commonly used in ERP experiments. (4) ERP morphology is different at the shortest compared to longer SOAs. Together, the results point to a special role of a near-normal presentation rate for visual word recognition and therefore suggest that SOA should be taken into account in research of natural reading. KW - Word recognition KW - Sentence reading KW - Stimulus onset asynchrony (SOA) KW - Frequency KW - Predictability KW - Event-related potentials (ERPs) Y1 - 2012 U6 - https://doi.org/10.1016/j.neuropsychologia.2012.04.011 SN - 0028-3932 VL - 50 IS - 8 SP - 1852 EP - 1870 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Henkel, Janin A1 - Frede, Katja A1 - Schanze, Nancy A1 - Vogel, Heike A1 - Schürmann, Annette A1 - Spruß, Astrid A1 - Bergheim, Ina A1 - Püschel, Gerhard Paul T1 - Stimulation of fat accumulation in hepatocytes by PGE(2)-dependent repression of hepatic lipolysis, beta-oxidation and VLDL-synthesis JF - Laboratory investigation : the basic and translational pathology research journal ; an official journal of the United States and Canadian Academy of Pathology N2 - Hepatic steatosis is recognized as hepatic presentation of the metabolic syndrome. Hyperinsulinaemia, which shifts fatty acid oxidation to de novo lipogenesis and lipid storage in the liver, appears to be a principal elicitor particularly in the early stages of disease development. The impact of PGE(2), which has previously been shown to attenuate insulin signaling and hence might reduce insulin-dependent lipid accumulation, on insulin-induced steatosis of hepatocytes was studied. The PGE(2)-generating capacity was enhanced in various obese mouse models by the induction of cyclooxygenase 2 and microsomal prostaglandin E-synthases (mPGES1, mPGES2). PGE(2) attenuated the insulin-dependent induction of SREBP-1c and its target genes glucokinase and fatty acid synthase. Nevertheless, PGE(2) enhanced incorporation of glucose into hepatic triglycerides synergistically with insulin. This was most likely due to a combination of a PGE(2)-dependent repression of (1) the key lipolytic enzyme adipose triglyceride lipase, (2) carnitine-palmitoyltransferase 1, a key regulator of mitochondrial beta-oxidation, and (3) microsomal transfer protein, as well as (4) apolipoprotein B, key components of the VLDL synthesis. Repression of PGC1 alpha, a common upstream regulator of these genes, was identified as a possible cause. In support of this hypothesis, overexpression of PGC1 alpha completely blunted the PGE(2)-dependent fat accumulation. PGE(2) enhanced lipid accumulation synergistically with insulin, despite attenuating insulin signaling and might thus contribute to the development of hepatic steatosis. Induction of enzymes involved in PGE(2) synthesis in in vivo models of obesity imply a potential role of prostanoids in the development of NAFLD and NASH. Laboratory Investigation (2012) 92, 1597-1606; doi:10.1038/labinvest.2012.128; published online 10 September 2012 KW - cyclooxygenase KW - hepatic steatosis KW - mPGES KW - NAFLD KW - NASH KW - type 2 diabetes (T2DM) KW - PGC1 alpha Y1 - 2012 U6 - https://doi.org/10.1038/labinvest.2012.128 SN - 0023-6837 VL - 92 IS - 11 SP - 1597 EP - 1606 PB - Nature Publ. Group CY - New York ER - TY - JOUR A1 - Melnick, Daniel A1 - Garcin, Yannick A1 - Quinteros, Javier A1 - Strecker, Manfred A1 - Olago, Daniel A1 - Tiercelin, Jean-Jacques T1 - Steady rifting in northern Kenya inferred from deformed Holocene lake shorelines of the Suguta and Turkana basins JF - Earth & planetary science letters N2 - A comparison of deformation rates in active rifts over different temporal scales may help to decipher variations in their structural evolution, controlling mechanisms, and evolution of sedimentary environments through time. Here we use deformed lake shorelines in the Suguta and Turkana basins in northern Kenya as strain markers to estimate deformation rates at the 10(3)-10(4) yr time scale and compare them with rates spanning 10(1)-10(7) yr. Both basins are internally drained today, but until 7 to 5 kyr lake levels were 300 and 100 m higher, respectively, maintained by the elevation of overflow sills connecting them with the Nile drainage. Protracted high lake levels resulted in formation of a maximum highstand shoreline - a distinct geomorphic feature virtually continuous for several tens of kilometers. We surveyed the elevation of this geomorphic marker at 45 sites along >100 km of the rift, and use the overflow sills as vertical datum. Thin-shell elastic and thermomechanical models for this region predict up to similar to 10 m of rapid isostatic rebound associated with lake-level falls lasting until similar to 2 kyr ago. Holocene cumulative throw rates along four rift-normal profiles are 6.8-8.5 mm/yr, or 7.5-9.6 mm/yr if isostatic rebound is considered. Assuming fault dips of 55-65, inferred from seismic reflection profiles, we obtained extension rates of 3.2-6 mm/yr (including uncertainties in field measurements, fault dips, and ages), or 3.5-6.7 mm/yr considering rebound. Our estimates are consistent, within uncertainties, with extension rates of 4-5.1 mm/yr predicted by a modern plate-kinematic model and plate reconstructions since 3.2 Myr. The Holocene strain rate of 10(-15) s(-1) is similar to estimates on the similar to 10(6) yr scale, but over an order of magnitude higher than on the similar to 10(7) yr scale. This is coherent with continuous localization and narrowing of the plate boundary, implying that the lithospheric blocks limiting the Kenya Rift are relatively rigid. Increasing strain rate under steady extension rate suggests that, as the magnitude of extension and crustal thinning increases, the role of regional processes such as weakening by volcanism becomes dominant over far-field plate tectonics controlling the breakup process and the transition from continental rifting to oceanic spreading. KW - continental rifting KW - East Africa KW - lake shorelines KW - Holocene extension KW - isostatic rebound Y1 - 2012 U6 - https://doi.org/10.1016/j.epsl.2012.03.007 SN - 0012-821X VL - 331 IS - 10 SP - 335 EP - 346 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Brückner, Michael A1 - Kanzow, Christian A1 - Scheffer, Tobias T1 - Static prediction games for adversarial learning problems JF - Journal of machine learning research N2 - The standard assumption of identically distributed training and test data is violated when the test data are generated in response to the presence of a predictive model. This becomes apparent, for example, in the context of email spam filtering. Here, email service providers employ spam filters, and spam senders engineer campaign templates to achieve a high rate of successful deliveries despite the filters. We model the interaction between the learner and the data generator as a static game in which the cost functions of the learner and the data generator are not necessarily antagonistic. We identify conditions under which this prediction game has a unique Nash equilibrium and derive algorithms that find the equilibrial prediction model. We derive two instances, the Nash logistic regression and the Nash support vector machine, and empirically explore their properties in a case study on email spam filtering. KW - static prediction games KW - adversarial classification KW - Nash equilibrium Y1 - 2012 SN - 1532-4435 VL - 13 SP - 2617 EP - 2654 PB - Microtome Publishing CY - Cambridge, Mass. ER - TY - THES A1 - Kiel, Mareike T1 - Static and ultrafast optical properties of nanolayered composites : gold nanoparticles embedded in polyelectrolytes T1 - Statische und ultraschnelle optische Eigenschaften von nanogeschichteten Kompositmaterialien. Gold-Nanopartikel in Polyelektrolytschichten. N2 - In the course of this thesis gold nanoparticle/polyelectrolyte multilayer structures were prepared, characterized, and investigated according to their static and ultrafast optical properties. Using the dip-coating or spin-coating layer-by-layer deposition method, gold-nanoparticle layers were embedded in a polyelectrolyte environment with high structural perfection. Typical structures exhibit four repetition units, each consisting of one gold-particle layer and ten double layers of polyelectrolyte (cationic+anionic polyelectrolyte). The structures were characterized by X-ray reflectivity measurements, which reveal Bragg peaks up to the seventh order, evidencing the high stratication of the particle layers. In the same measurements pronounced Kiessig fringes were observed, which indicate a low global roughness of the samples. Atomic force microscopy (AFM) images veried this low roughness, which results from the high smoothing capabilities of polyelectrolyte layers. This smoothing effect facilitates the fabrication of stratified nanoparticle/polyelectrolyte multilayer structures, which were nicely illustrated in a transmission electron microscopy image. The samples' optical properties were investigated by static spectroscopic measurements in the visible and UV range. The measurements revealed a frequency shift of the reflectance and of the plasmon absorption band, depending on the thickness of the polyelectrolyte layers that cover a nanoparticle layer. When the covering layer becomes thicker than the particle interaction range, the absorption spectrum becomes independent of the polymer thickness. However, the reflectance spectrum continues shifting to lower frequencies (even for large thicknesses). The range of plasmon interaction was determined to be in the order of the particle diameter for 10 nm, 20 nm, and 150 nm particles. The transient broadband complex dielectric function of a multilayer structure was determined experimentally by ultrafast pump-probe spectroscopy. This was achieved by simultaneous measurements of the changes in the reflectance and transmittance of the excited sample over a broad spectral range. The changes in the real and imaginary parts of the dielectric function were directly deduced from the measured data by using a recursive formalism based on the Fresnel equations. This method can be applied to a broad range of nanoparticle systems where experimental data on the transient dielectric response are rare. This complete experimental approach serves as a test ground for modeling the dielectric function of a nanoparticle compound structure upon laser excitation. N2 - Im Rahmen dieser Arbeit wurden Gold-Nanopartikel/Polyelektrolyt Multischichtstrukturen hergestellt, strukturell charakterisiert und bezüglich ihrer optischen Eigenschaften sowohl statisch als auch zeitaufgelöst analysiert. Die Strukturen wurden mithilfe der Dip-coating oder der Spin-coating Methode hergestellt. Beide Methoden ermöglichen das Einbetten einzelner Partikellagen in eine Polyelektrolytumgebung. Typische Strukturen in dieser Arbeit bestehen aus vier Wiederholeinheiten, wobei jede aus einer Nanopartikelschicht und zehn Polyelektrolyt-Doppellagen (kationisches und anionisches Polyelektrolyt) zusammengesetzt ist. Die Stratizierung der Gold-Nanopartikellagen wurde mittels Röntgenreflektometrie-Messungen im Kleinwinkelbereich nachgewiesen, welche Bragg Reflexionen bis zur siebten Ordnung aufzeigen. Das ausgeprägte Kiessig Interferenzmuster dieser Messungen weist zudem auf eine geringe globale Rauheit hin, die durch Oberflächenanalysen mit einem Rasterkraftmikroskop bestätigt werden konnte. Diese geringe Rauheit resultiert aus den glättenden Eigenschaften der Polyelektrolyte, die die Herstellung von Multilagensystemen mit mehreren Partikellagen erst ermöglichen. Die Aufnahme eines Transmissionselektronenmikroskops veranschaulicht eindrucksvoll die Anordnung der Partikel in einzelne Schichten. Durch photospektroskopische Messungen wurden die optischen Eigenschaften der Strukturen im UV- und sichtbaren Bereich untersucht. Beispielsweise wird eine Verschiebung und Verstärkung der Plasmonenresonanz beobachtet, wenn eine Goldnanopartikellage mit transparenten Polyelektrolyten beschichtet wird. Erst wenn die bedeckende Schicht dicker als die Reichweite der Plasmonen wird, bleibt die Absorption konstant. Die spektrale Reflektivität jedoch ändert sich auch mit jeder weiteren adsorbierten Polyelektrolytschicht. Die Reichweite der Plasmonenresonanz konnte auf diese Art für Partikel der Größe 10 nm, 20 nm und 150 nm bestimmt werden. Die Ergebnisse wurden im Kontext einer Effektiven Mediums Theorie diskutiert. Die komplexe dielektrische Funktion einer Multilagenstruktur wurde zeitabhängig nach Laserpulsanregung für einen breiten spektralen Bereich bestimmt. Dazu wurden zuerst die Änderungen der Reflektivität und Transmittivität simultan mittels der Pump-Probe (Anrege-Abtast) Spektroskopie gemessen. Anschließend wurden aus diesen Daten, mithilfe eines Formalismus, der auf den Fresnelschen Formeln basiert, die Änderungen im Real- und Imaginärteil der dielektrischen Funktion ermittelt. Diese Methode eignet sich zur Bestimmung der transienten dielektrischen Funktion einer Vielzahl von Nanopartikelsystemen. Der rein experimentelle Ansatz ermöglicht es, effektive Medien Theorien und Simulationen der dielektrischen Funktion nach Laserpulsanregung zu überprüfen. KW - Nanopartikel KW - Polyelektrolyte KW - Dielektrische Funktion KW - Anrege-Abtast Spektroskopie KW - nanoparticles KW - polyelectrolytes KW - dielectric function KW - pump-probe spectroscopy Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-61823 ER - TY - JOUR A1 - Müller, Steffen A1 - Carlsohn, Anja A1 - Müller, Juliane A1 - Baur, Heiner A1 - Mayer, Frank T1 - Static and dynamic foot characteristics in children aged 1-13 years a cross-sectional study JF - Gait & posture N2 - The aim of this study was to acquire static and dynamic foot geometry and loading in childhood, and to establish data for age groups of a population of 1-13 year old infants and children. A total of 10,382 children were recruited and 7788 children (48% males and 52% females) were finally included into the data analysis. For static foot geometry foot length and foot width were quantified in a standing position. Dynamic foot geometry and loading were assessed during walking on a walkway with self selected speed (Novel Emed X, 100 Hz, 4 sensors/cm(2)). Contact area (CA), peak pressure (PP), force time integral (FTI) and the arch index were calculated for the total, fore-, mid- and hindfoot. Results show that most static and dynamic foot characteristics change continuously during growth and maturation. Static foot length and width increased with age from 13.1 +/- 0.8 cm (length) and 5.7 +/- 0.4 cm (width) in the youngest to 24.4 +/- 1.5 cm (length) and 8.9 +/- 0.6 cm (width) in the oldest. A mean walking velocity of 0.94 +/- 0.25 m/s was observed. Arch-index ranged from 0.32 +/- 0.04 [a.u.] in the one-year old to 0.21 +/- 0.13 [a.u.] in the 5-year olds and remains constant afterwards. This study provides data for static and dynamic foot characteristics in children based on a cohort of 7788 subjects. Static and dynamic foot measures change differently during growth and maturation. Dynamic foot measurements provide additional information about the children's foot compared to static measures. KW - Children KW - Foot KW - Geometry KW - Arch-index KW - Plantar pressure Y1 - 2012 U6 - https://doi.org/10.1016/j.gaitpost.2011.10.357 SN - 0966-6362 VL - 35 IS - 3 SP - 389 EP - 394 PB - Elsevier CY - Clare ER - TY - JOUR A1 - Zimmermann, Andreas T1 - State sucession in treaties Y1 - 2012 SN - 978-0-19-929168-7 ER - TY - JOUR A1 - Zimmermann, Andreas T1 - State sucession in other matters than treaties Y1 - 2012 SN - 978-0-19-929168-7 ER - TY - CHAP A1 - Laschewsky, André A1 - Herfurth, Christoph A1 - Miasnikova, Anna A1 - Wieland, Christoph A1 - Wischerhoff, Erik A1 - Gradzielski, Michael A1 - de Molina, Paula Malo A1 - Weiss, Jan T1 - Stars and blocks tailoring polymeric rheology modifiers for aqueous media by controlled free radical polymerization T2 - Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS Y1 - 2012 SN - 0065-7727 VL - 244 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Khalil, Mahmoud A1 - Raila, Jens A1 - Ali, Mostafa A1 - Islam, Khan M. S. A1 - Schenk, Regina A1 - Krause, Jens-Peter A1 - Schweigert, Florian J. A1 - Rawel, Harshadrai Manilal T1 - Stability and bioavailability of lutein ester supplements from Tagetes flower prepared under food processing conditions JF - Journal of functional food N2 - Tagetes spp. belongs to the Asteraceae family. It is recognized as a major source of lutein ester (lutein esterified with fatty acids such as lauric, myristic and palmitic acids), a natural colorant belonging to the xanthophylls or oxygenated carotenoids. Four species of Tagetes flower (Tagetes tenuifolia, Tagetes erecta, Tagetes patula, and Tagetes lucida) were used to extract lutein and lutein esters with three different methods. The results showed that T. erecta, type "orangeprinz", is the richest source of lutein esters (14.4 +/- 0.234 mg/g) in comparison to other Tagetes spp. No significant differences between extractions of lutein esters with medium-chain triacylglycerols (MCT) oil, orange oil or solvent (hexane/isopropanol) could be observed. MCT oil also improved stability of lutein esters at 100 degrees C for 40 min. Emulsification of MCT oil improved the stability of lutein ester extract against UV light at 365 nm for 72 h. Finally, an emulsion was prepared under food processing conditions, spray dried and its bioavailability investigated in a preliminary human intervention study. The results show a lower resorption, but further data suggest improvements in implementation of such supplements. (c) 2012 Elsevier Ltd. All rights reserved. KW - Tagetes KW - Lutein ester KW - Emulsion KW - Stability KW - Whey protein KW - Bioavailability Y1 - 2012 U6 - https://doi.org/10.1016/j.jff.2012.03.006 SN - 1756-4646 VL - 4 IS - 3 SP - 602 EP - 610 PB - Elsevier CY - Amsterdam ER - TY - GEN A1 - Martins, Fabrice A1 - Bergemann, Maria A1 - Bestenlehner, Joachim M. A1 - Crowther, Paul A. A1 - Hamann, Wolf-Rainer A1 - Najarro, Francisco A1 - Nieva, Maria Fernanda A1 - Przybilla, Norbert A1 - Freimanis, Juris A1 - Hou, Weizhen A1 - Kaper, Lex T1 - SpS5 - II. Stellar and wind parameters T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The development of infrared observational facilities has revealed a number of massive stars in obscured environments throughout the Milky Way and beyond. The determination of their stellar and wind properties from infrared diagnostics is thus required to take full advantage of the wealth of observations available in the near and mid infrared. However, the task is challenging. This session addressed some of the problems encountered and showed the limitations and successes of infrared studies of massive stars. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 688 KW - infrared: stars KW - stars: early-type KW - stars: late-type KW - stars: fundamental parameters KW - stars: mass loss KW - stars: abundances Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-414956 SN - 1866-8372 IS - 688 ER - TY - JOUR A1 - Roy, S. A1 - Pikovskij, Arkadij T1 - Spreading of energy in the Ding-Dong model JF - Chaos : an interdisciplinary journal of nonlinear science N2 - We study the properties of energy spreading in a lattice of elastically colliding harmonic oscillators (Ding-Dong model). We demonstrate that in the regular lattice the spreading from a localized initial state is mediated by compactons and chaotic breathers. In a disordered lattice, the compactons do not exist, and the spreading eventually stops, resulting in a finite configuration with a few chaotic spots. Y1 - 2012 U6 - https://doi.org/10.1063/1.3695369 SN - 1054-1500 VL - 22 IS - 2 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Melnick, Daniel A1 - Moreno, Marcos A1 - Motagh, Mahdi A1 - Cisternas, Marco A1 - Wesson, Robert L. T1 - Splay fault slip during the M-w 8.8 2010 Maule Chile earthquake JF - Geology N2 - Splay faults are thrusts that emerge from the plate boundaries of subduction zones. Such structures have been mapped at several convergent margins and their activity commonly ascribed to large megathrust earthquakes. However, the behavior of splay faults during the earthquake cycle is poorly constrained because typically these structures are located offshore and are difficult to access. Here we use geologic mapping combined with space and land geodesy, as well as offshore sonar data, to document surface-fault ruptures and coastal uplift at Isla Santa Maria in south-central Chile (37 degrees S) caused by the 27 February 2010 Maule earthquake (M-w 8.8). During the earthquake, the island was tilted parallel to the margin, and normal faults ruptured the surface and adjacent ocean bottom. We associate tilt and crestal normal faulting with growth of an anticline above a blind reverse fault rooted in the Nazca-South America plate boundary, which slipped during the Maule earthquake. The splay fault system has formed in an area of reduced coseismic plate-boundary slip, suggesting that anelastic deformation in the upper plate may have restrained the 2010 megathrust rupture. Surface fault breaks were accompanied by prominent discharge of fluids. Our field observations support the notion that splay faulting may frequently complement and influence the rupture of subduction-zone earthquakes. Y1 - 2012 U6 - https://doi.org/10.1130/G32712.1 SN - 0091-7613 VL - 40 IS - 3 SP - 251 EP - 254 PB - American Institute of Physics CY - Boulder ER - TY - THES A1 - Scholz, Markus Reiner T1 - Spin polarization, circular dichroism, and robustness of topological surface states : a photoemission study Y1 - 2012 CY - Potsdam ER - TY - THES A1 - Scholz, Markus Reiner T1 - Spin polarization, circular dichroism, and robustness of topological surface states T1 - Spinpolarisation, Zirkulardichroismus und Robustheit Topologischer Oberflächenzustände BT - a photoemission study BT - eine Photoemissionsstudie N2 - Dreidimensionale topologische Isolatoren sind ein neues Materialsystem, welches dadurch charakterisiert ist, dass es in seinem Inneren isolierend an der Ober äche jedoch leitend ist. Ursächlich für die Leitfähigkeit an der Ober äche sind sogenannte topologische Ober- ächenzustände, welche das Valenzband des Inneren mit dem Leitungsband des Inneren verbinden. An der Ober äche ist also die Bandlücke, welche die isolierende Eigenschaft verursacht, geschlossen. Die vorliegende Arbeit untersucht diese Ober ächenzustände mittels spin- und winkelauf- gelöster Photoemissionsspektroskopie. Es wird gezeigt, dass in den Materialien Bi2Se3 und Bi2Te3, in übereinstimmung mit der Literatur, die entscheidenden Charakteristika eines topologischen Ober ächenzustands vorzu nden sind: Die Ober ächenzustände dieser Sys- teme durchqueren die Bandlücke in ungerader Anzahl, sie sind nicht entartet und weisen folgerichtig eine hohe Spinpolarisation auf. Weiterhin wird durch Aufdampfen diverser Adsorbate gezeigt, dass der Ober ächenzustän- de von Bi2Se3 und Bi2Te3, wie erwartet, extrem robust ist. Ober ächenzustände topologisch trivialer Systeme erfüllen diese Eigenschaft nicht; bereits kleine Verunreinigungen kön- nen diese Zustände zerstören, bzw. die Ober äche isolierend machen. Die topologischen Ober ächenzustände können in der vorliegenden Arbeit noch bis zur Detektionsgrenze der experimentellen Messmethode nachgewiesen werden und die Ober äche bleibt Leitfähig. Unter den Adsorbaten be ndet sich auch Eisen, ein bekanntermaßen magnetisches Materi- al. Eine der Grundvoraussetzungen für topologische Isolatoren ist die Zeitumkehrsymme- trie, die Elektronen, welche den topologischen Ober ächenzustand besetzen, vorschreibt, dass sie eine bestimmte Spinrichtung haben müssen, wenn sie sich beispielsweise nach links bewegen und den entgegengesetzten Spin wenn sie sich nach rechts bewegen. In magnetischen Materialien ist die Zeitumkehrsymmetrie jedoch explizit gebrochen und die gezeigte Robustheit des Ober ächenzustands gegen magnetische Materialien daher uner- wartet. Die Zeitumkehrsymmetrie sorgt auch dafür, dass eine Streuung der Elektronen um 180°, beispielsweise an einem Gitterdefekt oder an einem Phonon strikt verboten ist. Bei einem solchen Streuprozess bleibt die Spinrichtung erhalten, da aber in der Gegenrichtung nur Zustände mit entgegengesetztem Spin vorhanden sind kann das Elektron nicht in diese Richtung gestreut werden. Dieses Prinzip wird anhand der Lebensdauer der durch Pho- toemission angeregten Zustände untersucht. Hierbei wird gezeigt, dass die Kopplung der Elektronen des Ober ächenzustands von Bi2Te3 an Phononen unerwartet hoch ist und dass sich eine Anisotropie in der Bandstruktur des Selbigen auch in den Lebensdauern der ange- regten Zustände widerspiegelt. Weiterhin wird gezeigt, dass sich die Ein üsse von magne- tischen und nicht-magnetischen Verunreinigungen auf die Lebensdauern stark voneinander unterscheiden. Im letzten Teil der vorliegenden Arbeit wird untersucht, ob eine Asymmetrie in der Inten- sitätsverteilung der winkelaufgelösten Photoemissionsspektren, bei Anregung mit zirku- lar polarisiertem Licht, in Bi2Te3 Rückschlüsse auf die Spinpolarisation der Elektronen erlaubt. Bei Variation der Energie des eingestrahlten Lichts wird ein Vorzeichenwechsel der Asymmetrie beobachtet. Daraus lässt sich schlussfolgern, dass die Asymmetrie keine Rückschlüsse auf die Spinpolarisation erlaubt. N2 - This thesis is focussed on the electronic properties of the new material class named topological insulators. Spin and angle resolved photoelectron spectroscopy have been applied to reveal several unique properties of the surface state of these materials. The first part of this thesis introduces the methodical background of these quite established experimental techniques. In the following chapter, the theoretical concept of topological insulators is introduced. Starting from the prominent example of the quantum Hall effect, the application of topological invariants to classify material systems is illuminated. It is explained how, in presence of time reversal symmetry, which is broken in the quantum Hall phase, strong spin orbit coupling can drive a system into a topologically non trivial phase. The prediction of the spin quantum Hall effect in two dimensional insulators an the generalization to the three dimensional case of topological insulators is reviewed together with the first experimental realization of a three dimensional topological insulator in the Bi1-xSbx alloys given in the literature. The experimental part starts with the introduction of the Bi2X3 (X=Se, Te) family of materials. Recent theoretical predictions and experimental findings on the bulk and surface electronic structure of these materials are introduced in close discussion to our own experimental results. Furthermore, it is revealed, that the topological surface state of Bi2Te3 shares its orbital symmetry with the bulk valence band and the observation of a temperature induced shift of the chemical potential is to a high probability unmasked as a doping effect due to residual gas adsorption. The surface state of Bi2Te3 is found to be highly spin polarized with a polarization value of about 70% in a macroscopic area, while in Bi2Se3 the polarization appears reduced, not exceeding 50%. We, however, argue that the polarization is most likely only extrinsically limited in terms of the finite angular resolution and the lacking detectability of the out of plane component of the electron spin. A further argument is based on the reduced surface quality of the single crystals after cleavage and, for Bi2Se3 a sensitivity of the electronic structure to photon exposure. We probe the robustness of the topological surface state in Bi2X3 against surface impurities in Chapter 5. This robustness is provided through the protection by the time reversal symmetry. Silver, deposited on the (111) surface of Bi2Se3 leads to a strong electron doping but the surface state is observed up to a deposited Ag mass equivalent to one atomic monolayer. The opposite sign of doping, i.e., hole-like, is observed by exposing oxygen to Bi2Te3. But while the n-type shift of Ag on Bi2Se3 appears to be more or less rigid, O2 is lifting the Dirac point of the topological surface state in Bi2Te3 out of the valence band minimum at $\Gamma$. After increasing the oxygen dose further, it is possible to shift the Dirac point to the Fermi level, while the valence band stays well beyond. The effect is found reversible, by warming up the samples which is interpreted in terms of physisorption of O2. For magnetic impurities, i.e., Fe, we find a similar behavior as for the case of Ag in both Bi2Se3 and Bi2Te3. However, in that case the robustness is unexpected, since magnetic impurities are capable to break time reversal symmetry which should introduce a gap in the surface state at the Dirac point which in turn removes the protection. We argue, that the fact that the surface state shows no gap must be attributed to a missing magnetization of the Fe overlayer. In Bi2Te3 we are able to observe the surface state for deposited iron mass equivalents in the monolayer regime. Furthermore, we gain control over the sign of doping through the sample temperature during deposition. Chapter6 is devoted to the lifetime broadening of the photoemission signal from the topological surface states of Bi2Se3 and Bi2Te3. It is revealed that the hexagonal warping of the surface state in Bi2Te3 introduces an anisotropy for electrons traveling along the two distinct high symmetry directions of the surface Brillouin zone, i.e., $\Gamma$K and $\Gamma$M. We show that the phonon coupling strength to the surface electrons in Bi2Te3 is in nice agreement with the theoretical prediction but, nevertheless, higher than one may expect. We argue that the electron-phonon coupling is one of the main contributions to the decay of photoholes but the relatively small size of the Fermi surface limits the number of phonon modes that may scatter off electrons. This effect is manifested in the energy dependence of the imaginary part of the electron self energy of the surface state which shows a decay to higher binding energies in contrast to the monotonic increase proportional to E$^2$ in the Fermi liquid theory due to electron-electron interaction. Furthermore, the effect of the surface impurities of Chapter 5 on the quasiparticle life- times is investigated. We find that Fe impurities have a much stronger influence on the lifetimes as compared to Ag. Moreover, we find that the influence is stronger independently of the sign of the doping. We argue that this observation suggests a minor contribution of the warping on increased scattering rates in contrast to current belief. This is additionally confirmed by the observation that the scattering rates increase further with increasing silver amount while the doping stays constant and by the fact that clean Bi2Se3 and Bi2Te3 show very similar scattering rates regardless of the much stronger warping in Bi2Te3. In the last chapter we report on a strong circular dichroism in the angle distribution of the photoemission signal of the surface state of Bi2Te3. We show that the color pattern obtained by calculating the difference between photoemission intensities measured with opposite photon helicity reflects the pattern expected for the spin polarization. However, we find a strong influence on strength and even sign of the effect when varying the photon energy. The sign change is qualitatively confirmed by means of one-step photoemission calculations conducted by our collaborators from the LMU München, while the calculated spin polarization is found to be independent of the excitation energy. Experiment and theory together unambiguously uncover the dichroism in these systems as a final state effect and the question in the title of the chapter has to be negated: Circular dichroism in the angle distribution is not a new spin sensitive technique. KW - topological insulators KW - angle resolved photoelectron spectroscopy KW - spin resolved photoelectron spectroscopy KW - Bi2Se3 KW - Bi2Te3 KW - quasiparticle interactions KW - circular dichroism KW - spin-orbit coupling KW - time reversal symmetry KW - surface states KW - Spinpolarisation KW - Zirkulardichroismus KW - topologische Isolatoren KW - Oberflächenzustände KW - winkelaufgelöste Photoelektronenspektroskopie KW - spinaufgelöste Photoelektronenspektroskopie KW - Magnetismus KW - Bi2Te3 KW - Bi2Se3 Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-96686 ER - TY - JOUR A1 - Schmitz, Elisabeth I. A1 - Potteck, Henrik A1 - Schüppel, Melanie A1 - Manggau, Marianti A1 - Wahydin, Elly A1 - Kleuser, Burkhard T1 - Sphingosine 1-phosphate protects primary human keratinocytes from apoptosis via nitric oxide formation through the receptor subtype S1P(3) JF - Molecular and cellular biochemistry : an international journal for chemical biology in health and disease N2 - Although the lipid mediator sphingosine 1-phosphate (S1P) has been identified to induce cell growth arrest of human keratinocytes, the sphingolipid effectively protects these epidermal cells from apoptosis. The molecular mechanism of the anti-apoptotic action induced by S1P is less characterized. Apart from S1P, endogenously produced nitric oxide (NOaEuro cent) has been recognized as a potent modulator of apoptosis in keratinocytes. Therefore, it was of great interest to elucidate whether S1P protects human keratinocytes via a NOaEuro cent-dependent signalling pathway. Indeed, S1P induced an activation of endothelial nitric oxide synthase (eNOS) in human keratinocytes leading to an enhanced formation of NOaEuro cent. Most interestingly, the cell protective effect of S1P was almost completely abolished in the presence of the eNOS inhibitor L-NAME as well as in eNOS-deficient keratinocytes indicating that the sphingolipid metabolite S1P protects human keratinocytes from apoptosis via eNOS activation and subsequent production of protective amounts of NOaEuro cent. It is well established that most of the known actions of S1P are mediated by a family of five specific G protein-coupled receptors. Therefore, the involvement of S1P-receptor subtypes in S1P-mediated eNOS activation has been examined. Indeed, this study clearly shows that the S1P(3) is the exclusive receptor subtype in human keratinocytes which mediates eNOS activation and NOaEuro cent formation in response to S1P. In congruence, when the S1P(3) receptor subtype is abrogated, S1P almost completely lost its ability to protect human keratinocytes from apoptosis. KW - Keratinocytes KW - Sphingolipids KW - Sphingosine 1-phosphate KW - S1P-receptors KW - Nitric oxide KW - Endothelial nitric oxide synthase KW - Apoptosis Y1 - 2012 U6 - https://doi.org/10.1007/s11010-012-1433-5 SN - 0300-8177 VL - 371 IS - 1-2 SP - 165 EP - 176 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Japtok, Lukasz A1 - Schaper, Katrin A1 - Bäumer, Wolfgang A1 - Radeke, Heinfried H. A1 - Jeong, Se Kyoo A1 - Kleuser, Burkhard T1 - Sphingosine 1-Phosphate Modulates Antigen Capture by Murine Langerhans Cells via the S1P(2) Receptor Subtype JF - PLOS ONE N2 - Dendritic cells (DCs) play a pivotal role in the development of cutaneous contact hypersensitivity (CHS) and atopic dermatitis as they capture and process antigen and present it to T lymphocytes in the lymphoid organs. Recently, it has been indicated that a topical application of the sphingolipid sphingosine 1-phosphate (S1P) prevents the inflammatory response in CHS, but the molecular mechanism is not fully elucidated. Here we indicate that treatment of mice with S1P is connected with an impaired antigen uptake by Langerhans cells (LCs), the initial step of CHS. Most of the known actions of S1P are mediated by a family of five specific G protein-coupled receptors. Our results indicate that S1P inhibits macropinocytosis of the murine LC line XS52 via S1P(2) receptor stimulation followed by a reduced phosphatidylinositol 3-kinase (PI3K) activity. As down-regulation of S1P(2) not only diminished S1P-mediated action but also enhanced the basal activity of LCs on antigen capture, an autocrine action of S1P has been assumed. Actually, S1P is continuously produced by LCs and secreted via the ATP binding cassette transporter ABCC1 to the extracellular environment. Consequently, inhibition of ABCC1, which decreased extracellular S1P levels, markedly increased the antigen uptake by LCs. Moreover, stimulation of sphingosine kinase activity, the crucial enzyme for S1P formation, is connected not only with enhanced S1P levels but also with diminished antigen capture. These results indicate that S1P is essential in LC homeostasis and influences skin immunity. This is of importance as previous reports suggested an alteration of S1P levels in atopic skin lesions. Citation: Japtok L, Schaper K, Baumer W, Radeke HH, Jeong SK, et al. (2012) Sphingosine 1-Phosphate Modulates Antigen Capture by Murine Langerhans Cells via the S1P(2) Receptor Subtype. PLoS ONE 7(11): e49427. doi:10.1371/journal.pone.0049427 Y1 - 2012 U6 - https://doi.org/10.1371/journal.pone.0049427 SN - 1932-6203 VL - 7 IS - 11 PB - PUBLIC LIBRARY SCIENCE CY - SAN FRANCISCO ER - TY - JOUR A1 - Kuehnel, Susanne A1 - Kupfer, Alexander T1 - Sperm storage in caecilian amphibians Y1 - 2012 UR - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3418217/pdf/1742-9994-9-12.pdf U6 - https://doi.org/10.1186/1742-9994-9-12 ER - TY - JOUR A1 - Kühnel, Susanne A1 - Kupfer, Alexander T1 - Sperm storage in caecilian amphibians JF - Frontiers in zoology N2 - Background: Female sperm storage has evolved independently multiple times among vertebrates to control reproduction in response to the environment. In internally fertilising amphibians, female salamanders store sperm in cloacal spermathecae, whereas among anurans sperm storage in oviducts is known only in tailed frogs. Facilitated through extensive field sampling following historical observations we tested for sperm storing structures in the female urogenital tract of fossorial, tropical caecilian amphibians. Findings: In the oviparous Ichthyophis cf. kohtaoensis, aggregated sperm were present in a distinct region of the posterior oviduct but not in the cloaca in six out of seven vitellogenic females prior to oviposition. Spermatozoa were found most abundantly between the mucosal folds. In relation to the reproductive status decreased amounts of sperm were present in gravid females compared to pre-ovulatory females. Sperm were absent in females past oviposition. Conclusions: Our findings indicate short-term oviductal sperm storage in the oviparous Ichthyophis cf. kohtaoensis. We assume that in female caecilians exhibiting high levels of parental investment sperm storage has evolved in order to optimally coordinate reproductive events and to increase fitness. KW - Reproduction KW - Sperm storage KW - Amphibians KW - Caecilians Y1 - 2012 U6 - https://doi.org/10.1186/1742-9994-9-12 SN - 1742-9994 VL - 9 IS - 23 PB - BioMed Central CY - London ER - TY - INPR A1 - Alsaedy, Ammar A1 - Tarkhanov, Nikolai Nikolaevich T1 - Spectral projection for the dbar-Neumann problem N2 - We show that the spectral kernel function of the dbar-Neumann problem on a non-compact strongly pseudoconvex manifold is smooth up to the boundary. T3 - Preprints des Instituts für Mathematik der Universität Potsdam - 1(2012)12 KW - dbar-Neumann problem KW - strongly pseudoconvex domains KW - spectral kernel function Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-58616 SN - 2193-6943 ER - TY - JOUR A1 - Baushev, Anton N. A1 - Federici, S. A1 - Pohl, M. T1 - Spectral analysis of the gamma-ray background near the dwarf MilkyWay satellite Segue 1: Improved limits on the cross section of neutralino dark matter annihilation JF - Physical review : D, Particles, fields, gravitation, and cosmology N2 - The indirect detection of dark matter requires that dark matter annihilation products be discriminated from conventional astrophysical backgrounds. Here, we re-analyze GeV-band gamma-ray observations of the prominent Milky Way dwarf satellite galaxy Segue 1, for which the expected astrophysical background is minimal. We explicitly account for the angular extent of the conservatively expected gamma-ray signal and keep the uncertainty in the dark-matter profile external to the likelihood analysis of the gamma-ray data. Y1 - 2012 U6 - https://doi.org/10.1103/PhysRevD.86.063521 SN - 1550-7998 VL - 86 IS - 6 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Thierbach, Rene A1 - Florian, Simone A1 - Wolfrum, Katharina A1 - Voigt, Anja A1 - Drewes, Gunnar A1 - Blume, Urte A1 - Bannasch, Peter A1 - Ristow, Michael A1 - Steinberg, Pablo T1 - Specific alterations of carbohydrate metabolism are associated with hepatocarcinogenesis in mitochondrially impaired mice JF - Human molecular genetics N2 - Friedreich's ataxia is an inherited neurodegenerative disease caused by the reduced expression of the mitochondrially active protein frataxin. We have previously shown that mice with a hepatocyte-specific frataxin knockout (AlbFxn(-/-)) develop multiple hepatic tumors in later life. In the present study, hepatic carbohydrate metabolism in AlbFxn(-/-) mice at an early and late life stage was analyzed. In young (5-week-old) AlbFxn(-/-) mice hepatic ATP, glucose-6-phosphate and glycogen levels were found to be reduced by similar to 74, 80 and 88%, respectively, when compared with control animals. This pronounced ATP, G6P and glycogen depletion in the livers of young mice reverted in older animals: while half of the mice die before 30 weeks of age, the other half reaches 17 months of age and exhibits glycogen, G6P and ATP levels similar to those in age-matched controls. A key event in this respect seems to be the up-regulation of GLUT1, the predominant glucose transporter in fetal liver parenchyma, which became evident in AlbFxn(-/-) mice being 5-12 weeks of age. The most significant histological findings in animals being 17 or 22 months of age were the appearance of multiple clear cell, mixed cell and basophilic foci throughout the liver parenchyma as well as the development of hepatocellular adenomas and carcinomas. The hepatocarcinogenic process in AlbFxn 2/2 mice shows remarkable differences regarding carbohydrate metabolism alterations when compared with all other chemically and virally driven liver cancer models described up to now. Y1 - 2012 U6 - https://doi.org/10.1093/hmg/ddr499 SN - 0964-6906 VL - 21 IS - 3 SP - 656 EP - 663 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Piepho, Maike A1 - Arts, Michael T. A1 - Wacker, Alexander T1 - Species-specific variation in fatty acid concentrations of four phytoplankton species does phosphorus supply influence the effect of light intensity of temperature? JF - Journal of phycology N2 - We tested, in the laboratory, the influence of light intensity, temperature, and phosphorus (P) supply on fatty acid (FA) concentrations of four freshwater algae: the green algae Scenedesmus quadricauda (Turpin) Breb. and Chlamydomonas globosa J. Snow, the cryptophyte Cryptomonas ovata Ehrenb., and the diatom Cyclotella meneghiniana Kutz. We investigated the main and interactive effects of two variables on algal FA concentrations (i.e., light intensity and P supply or temperature and P supply). Interactive effects of light intensity and P supply were most pronounced in C. meneghiniana, but were also found in S. quadricauda and C. ovata. Changes in several saturated and unsaturated FA concentrations with light were more distinct in the low-P treatments than in the high-P treatments. Interactive effects of temperature and P supply on various FA concentrations were observed in all four species, but there was no consistent pattern. In lake ecosystems, P limitation often coincides with high light intensities and temperatures in summer. Therefore, it is important to examine how combinations of these environmental conditions affect FA concentrations of primary producers that are important sources of FAs for higher trophic levels. KW - Chlamydomonas KW - Cryptomonas KW - Cyclotella KW - fatty acids KW - light KW - lipids KW - phosphate KW - PUFA KW - Scenedesmus KW - temperature Y1 - 2012 U6 - https://doi.org/10.1111/j.1529-8817.2011.01103.x SN - 0022-3646 VL - 48 IS - 1 SP - 64 EP - 73 PB - Wiley-Blackwell CY - Malden ER - TY - INPR A1 - Weske, Mathias A1 - Yang, Jian A1 - Maglio, Paul P. T1 - Special issue service oriented computing (ICSOC) guest editors' introduction T2 - International journal of cooperative information systems Y1 - 2012 U6 - https://doi.org/10.1142/S0218843012020017 SN - 0218-8430 VL - 21 IS - 1 SP - 1 EP - 2 PB - World Scientific CY - Singapore ER - TY - JOUR A1 - Bookhagen, Bodo A1 - Strecker, Manfred T1 - Spatiotemporal trends in erosion rates across a pronounced rainfall gradient: Examples from the southern Central Andes JF - Earth & planetary science letters N2 - The tectonic and climatic boundary conditions of the broken foreland and the orogen interior of the southern Central Andes of northwestern Argentina cause strong contrasts in elevation, rainfall, and surface-process regimes. The climatic gradient in this region ranges from the wet, windward eastern flanks (similar to 2 m/yr rainfall) to progressively drier western basins and ranges (similar to 0.1 m/yr) bordering the arid Altiplano-Puna Plateau. In this study, we analyze the impact of spatiotemporal climatic gradients on surface erosion: First, we present 41 new catchment-mean erosion rates derived from cosmogenic nuclide inventories to document spatial erosion patterns. Second, we re-evaluate paleoclimatic records from the Calchaquies basin (66 W, 26 S), a large intermontane basin bordered by high (> 4.5 km) mountain ranges, to demonstrate temporal variations in erosion rates associated with changing climatic boundary conditions during the late Pleistocene and Holocene. Three key observations in this region emphasize the importance of climatic parameters on the efficiency of surface processes in space and time: (1) First-order spatial patterns of erosion rates can be explained by a simple specific stream power (SSP) approach. We explicitly account for discharge by routing high-resolution, satellite derived rainfall. This is important as the steep climatic gradient results in a highly non-linear relation between drainage area and discharge. This relation indicates that erosion rates (ER) scale with ER similar to SSP1.4 on cosmogenic-nuclide time scales. (2) We identify an intrinsic channel-slope behavior in different climatic compartments. Channel slopes in dry areas (< 0.25 m/yr rainfall) are slightly steeper than in wet areas (> 0.75 m/yr) with equal drainage areas, thus compensating lower amounts of discharge with steeper slopes. (3) Erosion rates can vary by an order of magnitude between presently dry (similar to 0.05 mm/yr) and well-defined late Pleistocene humid (similar to 0.5 mm/yr) conditions within an intemontane basin. Overall, we document a strong climatic impact on erosion rates and channel slopes. We suggest that rainfall reaching areas with steeper channel slopes in the orogen interior during wetter climate periods results in intensified sediment mass transport, which is primarily responsible for maintaining the balance between surface uplift, erosion, sediment routing and transient storage in the orogen. KW - erosion KW - landscape evolution KW - specific stream power KW - cosmogenic radionuclides KW - paleoclimate KW - climate-tectonic feedback processes Y1 - 2012 U6 - https://doi.org/10.1016/j.epsl.2012.02.005 SN - 0012-821X VL - 327 IS - 8 SP - 97 EP - 110 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Berenstein, Igal A1 - Beta, Carsten T1 - Spatiotemporal chaos arising from standing waves in a reaction-diffusion system with cross-diffusion JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - We show that quasi-standing wave patterns appear in the two-variable Oregonator model of the Belousov-Zhabotinsky reaction when a cross-diffusion term is added, no wave instability is required in this case. These standing waves have a frequency that is half the frequency of bulk oscillations displayed in the absence of diffusive coupling. The standing wave patterns show a dependence on the systems size. Regular standing waves can be observed for small systems, when the system size is an integer multiple of half the wavelength. For intermediate sizes, irregular patterns are observed. For large sizes, the system shows an irregular state of spatiotemporal chaos, where standing waves drift, merge, and split, and also phase slips may occur. Y1 - 2012 U6 - https://doi.org/10.1063/1.3676577 SN - 0021-9606 VL - 136 IS - 3 PB - American Institute of Physics CY - Melville ER -