Bayreuth, Germany
Bayreuth, Germany

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Bolognesi M.,University of Rennes 1 | Lonne M.,Universitatsstrasse 30
Selecta Mathematica, New Series | Year: 2016

In this paper, we study the topology of the stack $$\mathcal {T}_g$$Tg of smooth trigonal curves of genus g over the complex field. We make use of a construction by the first named author and Vistoli, which describes $$\mathcal {T}_g$$Tg as a quotient stack of the complement of the discriminant. This allows us to use techniques developed by the second named author to give presentations of the orbifold fundamental group of $$\mathcal {T}_g$$Tg, and of its substrata with prescribed Maroni invariant, and describe their relation with the mapping class group $$\mathcal {M}ap_g$$Mapg of Riemann surfaces of genus g. © 2015, Springer Basel.

Fishchuk I.I.,Ukrainian Academy of Sciences | Kadashchuk A.,IMEC | Kadashchuk A.,Ukrainian Academy of Sciences | Hoffmann S.T.,Universitatsstrasse 30 | And 4 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We developed an analytical model to describe hopping transport in organic semiconductors including both energetic disorder and polaronic contributions due to geometric relaxation. The model is based on a Marcus jump rate in terms of the small-polaron concept with a Gaussian energetic disorder, and it is premised upon a generalized effective medium approach yet avoids shortcomings involved in the effective transport energy or percolation concepts. It is superior to our previous treatment since it is applicable at arbitrary polaron activation energy Ea with respect to the energy disorder parameter σ. It can be adapted to describe both charge-carrier mobility and triplet exciton diffusion. The model is compared with results from Monte Carlo simulations. We show (i) that the activation energy of the thermally activated hopping transport can be decoupled into disorder and polaron contributions whose relative weight depend nonlinearly on the σ/Ea ratio, and (ii) that the choice of the density of occupied and empty states considered in configurational averaging has a profound effect on the results of calculations of the Marcus hopping transport. The σ/Ea ratio governs also the carrier-concentration dependence of the charge-carrier mobility in the large-carrier-concentration transport regime as realized in organic field-effect transistors. The carrier-concentration dependence becomes considerably weaker when the polaron energy increases relative to the disorder energy, indicating the absence of universality. This model bridges a gap between disorder and polaron hopping concepts. © 2013 American Physical Society.

Maphangwa K.W.,South African National Biodiversity Institute | Musil C.F.,South African National Biodiversity Institute | Raitt L.,University of the Western Cape | Zedda L.,Universitatsstrasse 30
Oecologia | Year: 2012

Elevated temperatures and diminished precipitation amounts accompanying climate warming in arid ecosystems are expected to have adverse effects on the photosynthesis of lichen species sensitive to elevated temperature and/or water limitation. This premise was tested by artificially elevating temperatures (increase 2.1-3.8°C) and reducing the amounts of fog and dew precipitation (decrease 30.1-31.9%), in an approximation of future climate warming scenarios, using transparent hexagonal open-top warming chambers placed around natural populations of four lichen species (Xanthoparmelia austroafricana, X. hyporhytida, Xanthoparmelia. sp., Xanthomaculina hottentotta) at a dry inland site and two lichen species (Teloschistes capensis and Ramalina sp.) at a humid coastal site in the arid South African Succulent Karoo Biome. Effective photosynthetic quantum yields (ΔF/F′ m) were measured hourly throughout the day at monthly intervals in pre-hydrated lichens present in the open-top warming chambers and in controls which comprised demarcated plots of equivalent open-top warming chamber dimensions constructed from 5-cm-diameter mesh steel fencing. The cumulative effects of the elevated temperatures and diminished precipitation amounts in the open-top warming chambers resulted in significant decreases in lichen (ΔF/F′ m). The decreases were more pronounced in lichens from the dry inland site (decline 34.1-46.1%) than in those from the humid coastal site (decline 11.3-13.7%), most frequent and prominent in lichens at both sites during the dry summer season, and generally of greatest magnitude at or after the solar noon in all seasons. Based on these results, we conclude that climate warming interacting with reduced precipitation will negatively affect carbon balances in endemic lichens by increasing desiccation damage and reducing photosynthetic activity time, leading to increased incidences of mortality. © 2011 Springer-Verlag.

Wang H.,Universitatsstrasse 30 | Synatschke C.V.,Universitatsstrasse 30 | Raup A.,University of Bayreuth | Jerome V.,University of Bayreuth | And 2 more authors.
Polymer Chemistry | Year: 2014

Dual functional antibacterial and biodegradable caprolactone (CL) based oligomers were prepared by ring-opening polymerization of caprolactone using a polyguanidine macroinitiator. Primary amino (-NH2) end-groups of linear poly(hexamethylene guanidine) hydrochloride (PHMG) acted as initiating sites for caprolactone polymerization leading to block copolymers which combine the antibacterial properties of PHMG with degradability provided by PCL. The block structure of the material was confirmed with 2D NMR and MALDI-ToF-MS. Furthermore, the material exhibited temperature dependent solubility (upper critical solution temperature) in polar solvents such as methanol. The oligomers showed high antibacterial activity (reduction of bacterial cells was more than 3 orders of magnitude) even at short incubation times depending on the concentration and PHMG : PCL ratio while maintaining enzymatic degradability and biocompatibility. © 2014 The Royal Society of Chemistry.

Gunther C.,Universitatsstrasse 30 | Schonig S.,Universitatsstrasse 30 | Jablonski S.,Universitatsstrasse 30
Proceedings of the ACM Symposium on Applied Computing | Year: 2012

Today's workflow management systems have become increasingly powerful. Some prototypic approaches even tend to not patronise the users by providing a set of process steps to follow, but let them decide which step to choose next. The idea behind this approach is the impossibility to model every special case of a workflow, because a fixed process order would necessarily be inefficient or even incorrect in some cases. By admitting this freedom, the risk of confounding the users is taken. That is why we provide a qualified guidance instance through the process. © 2012 Authors.

The intention of the educational concept "school in motion" is to promote a healthy lifestyle and an active school life. holistic learning, and a healthy lifestyle an an active school. The main concern ist to rhythmisize everyday school life by incorporating exercise and play to promote health, well-being and learning for children. This is all the more important, considering how much time pupils spent in all-day schools (Abeling und Städtler, 2008).

Dotterl M.,Universitatsstrasse 30 | Haas I.,Universitatsstrasse 30 | Alt H.G.,Universitatsstrasse 30
Zeitschrift fur Anorganische und Allgemeine Chemie | Year: 2011

The solubility of NbCl5, TaCl5, TiCl4, ZrCl4, and HfCl4 in neutral [BMIM][AlCl4] (BMIM = 1-butyl-3-methylimidazolium) was determined. While TiCl4 was immiscible with the neutral ionic liquid, 0.80 molar equivalents of ZrCl 4 and stoichiometric amounts of HfCl4 dissolved in the melt at ambient temperature. The crystal structures and the unit cell parameters of [BMIM]2[Ti2Cl10], [BMIM] 2[Zr2Cl10], and [PhNMe3][Hf 2Cl9] were determined. [BMIM]2[Ti 2Cl10], and [BMIM]2[Zr2Cl 10] were crystallised from basic chloroaluminate melts. With a trimethylanilinium cation, [PhNMe3][Hf2Cl9] crystallised from an equimolar composition of PhNMe3Cl, AlCl 3, and HfCl4. Obviously, HfCl4 abstracted a chloride ligand from [AlCl4]- to give highly Lewis acidic [Al2Cl7]- anions. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dotterl M.,Universitatsstrasse 30 | Alt H.G.,Universitatsstrasse 30
Catalysis Communications | Year: 2012

In the presence of molecular oxygen, [BMIM] +[Al 2Cl 7] - (BMIM = 1-butyl-3-methylimidazolium) ionic liquids catalyzed coupling reactions of cyclohexane and methylcyclohexane to give dimers and trimers. Further, conversions and reaction rates of n-heptane cracking and disproportionation reactions were strongly enhanced if an atmosphere of dry air was applied instead of an inert gas. © 2011 Elsevier B.V. All rights reserved.

Michlik S.,Universitatsstrasse 30 | Hille T.,Universitatsstrasse 30 | Kempe R.,Universitatsstrasse 30
Advanced Synthesis and Catalysis | Year: 2012

An iridium catalyst - stabilized by an anionic P,N ligand - was used for the symmetrical and unsymmetrical monoalkylation of para-, meta-, and ortho-benzenediamines. Benzyl and aliphatic alcohols were used as alkylating reagents. 28 derivatives were synthesized. 14 of them are new compounds. Furthermore, the alkylation of the pharmacological important diamine Dapson® (dapsone) is described. 14 dapsone derivatives were synthesized among them 9 new compounds. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Michlik S.,Universitatsstrasse 30 | Kempe R.,Universitatsstrasse 30
Chemistry - A European Journal | Year: 2010

The synthesis of eight new iridium complexes containing anionic P,N ligands is described. These complexes have been investigated as catalysts for amine alkylation reactions, resulting in a highly active catalyst for the selective monoalkylation of anilines with primary alcohols, under mild reaction conditions. Nearly quantitative conversion was observed at 70 °C with a catalyst loading as low as 0.05 mol % iridium. Selective amine alkylation: The synthesis of eight new iridium complexes containing anionic P,N ligands (see image) is described. These new complexes were used as highly active catalysts for the selective monoalkylation of anilines with primary alcohols, and gave nearly quantitative conversion under mild reaction conditions. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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