The development of German and French morphosyntactic spelling skills in multilingual pupils

Doctoral thesis (2018)

Integration of omics data for biotechnology-relevant microbial communities

Doctoral thesis (2018)

Naturally occurring and artificial bacterial communities play an import role in many biotechnological processes. To elucidate bacterial interactions that are important for potential optimized ... [more ▼]

Naturally occurring and artificial bacterial communities play an import role in many biotechnological processes. To elucidate bacterial interactions that are important for potential optimized biotechnological applications, high-throughput measurements of biomolecules, metagenomics, metratranscriptomics,metaproteomics, and meta-metabolomics provide a detailed snapshot of mixed microbial consortia. Integration of multiple layers of omics data allows to reconstruct structure and function of complex microbial communities and is demonstrated for two different model systems. The first chapter focuses on synthetic communities consisting of strains representing key species found in biomining operations and acid mine drainage and that are of economical interest for copper production. A high-quality closed reference genome for L. ferriphilum was obtained by DNA sequencing and was subsequently used to integrate functional omics data, i.e. transcriptomic and proteomic profiling. The combination of genomics, genome annotation, and functional omics data allowed an in-depth characterization of L. ferriphilum in culture medium and in the presence of the iron sulfide mineral chalcopyrite, an economically relevant copper ore. Subsequently, analyses were performed for co-cultures of up to three organisms highlighting specific interaction mechanisms. The cultures without L. ferriphilum showed higher copper solubilisation rates, as the highly efficient iron oxidiser might raise the redox potential above the optimal range. For in situ studies, reference-based analyses are of limited use, e.g. due to a lack in reference genomes of culturable isolates. Hence, the second chapter focuses on an approach to study mixed microbial communities independent of prior knowledge and available reference genomes. A timeseries of oleaginous floating sludge samples that spans over one and a half years was analysed by integrating metagenomic, metatranscriptomic, metaproteomic, and meta-metabolomic data. This allowed the reconstruction of population level genomes and the characterization of the niches of the respective populations. The functional potential was assessed, as well as expression profiles over time, yielding a detailed view on lifestyle strategies and the potential impact of abiotic factors. Understanding the niche ecology of the predominant lipid accumulators in the system could lead towards optimized biofuel production. [less ▲]

Alles anders? Was Digital Natives vom Arbeitsmarkt erwarten

Speeches/Talks (2018)

La confrontation Est-Ouest: une analyse d’images de la guerre froide

Presentation (2018, November 19)

Ce séminaire s’est focalisé sur l’examen des problématiques posées par la confrontation Est-Ouest et proposait une analyse critique d’images de la guerre froide à l’aide d’un outil numérique.

First-Principles Modeling of Molecular Crystals: Crystal Structure Prediction and Vibrational Properties

Doctoral thesis (2018)

Understanding the structure and stability, as well as response properties of molecular crystals at certain thermodynamic conditions is crucial for the engineering of new molecular materials and the design ... [more ▼]

Understanding the structure and stability, as well as response properties of molecular crystals at certain thermodynamic conditions is crucial for the engineering of new molecular materials and the design of pharmaceuticals. A reliable description of the polymorphic energy landscape of a molecular crystal would provide an extensive insight into the development of drugs in terms of the existence and the likelihood of late-appearing polymorphs. Furthermore, accurate modeling of low-frequency vibrational spectra would be important for the characterization of molecular crystal polymorphs. However, an accurate description of molecular crystals is very challenging since many properties highly depend on the crystal-packing arrangement of the involved molecules and the temperature. The difficulties for computational predictions of molecular crystal polymorphs lie in the high dimensionality of crystallographic and conformational space, and the need for very accurate relative free energies. It was shown that accurate lattice energies can be obtained by using density-functional theory (DFT) calculations supplemented by a high-level model for long-range van der Waals (vdW) dispersion interactions, such as the many-body dispersion (MBD) model. Therefore, this thesis utilizes throughout vdW-inclusive DFT using the MBD and the related pairwise Tkatchenko-Scheffler (TS) dispersion model and the importance of dispersion interactions is highlighted for several properties. A hierarchical stability-ranking approach based on the DFT+MBD framework for the final stage of a molecular crystal structure prediction procedure is presented and analyzed. This approach provides excellent stability rankings over the diverse set of molecular crystals studied in the latest blind test of the Cambridge Crystallographic Data Centre. The results suggest that accounting for many-body dispersion effects and vibrational free energies can be crucial for the description of relative stabilities, especially for highly polymorphic systems. The presented approach enables the calculation of reliable structures and thermodynamic stabilities for pharmaceutically relevant systems, contributing to a better understanding of complex polymorphic energy landscapes. Furthermore, many first-principles calculations are performed by using fully optimized structures and free energies obtained within the harmonic approximation, neglecting the thermal expansion of the studied molecular crystal and further anharmonic effects. Therefore, this thesis illustrates that the majority of the thermal expansion of molecular crystals can be captured with the used methods by applying the quasi-harmonic approximation. In addition, we estimate further anharmonic effects on the vibrational frequencies by utilizing Morse oscillators. [less ▲]

Z4 parafermions in one-dimensional fermionic lattices

in Physical Review. B, Condensed Matter (2018), 98

Parafermions are emergent excitations which generalize Majorana fermions and are potentially relevant to topological quantum computation. Using the concept of Fock parafermions, we present a mapping ... [more ▼]

Parafermions are emergent excitations which generalize Majorana fermions and are potentially relevant to topological quantum computation. Using the concept of Fock parafermions, we present a mapping between lattice Z4-parafermions and lattice spin-1/2 fermions which preserves the locality of operators with Z4 symmetry. Based on this mapping, we construct an exactly solvable, local one-dimensional fermionic Hamiltonian which hosts parafermionic edge states. We numerically show that the parafermionic phase remains stable in a wide range of parameters, and discuss its signatures in the fermionic spectral function. [less ▲]

Metallographic Studies of Dissimilar Al-Cu Laser-Welded Joints Using Various Etchants

in Metallography, Microstructure, and Analysis (2018)

The welding of Al and Cu is considered as difficult due to the formation of intermetallic compounds, which cause a brittle joint with increased electrical resistance. This paper investigates etching ... [more ▼]

The welding of Al and Cu is considered as difficult due to the formation of intermetallic compounds, which cause a brittle joint with increased electrical resistance. This paper investigates etching techniques that were used to contrast the intermetallic compounds for optical microscope analysis. A 0.5 mm AA-1050 sheet was welded to a 0.5 mm SF-Cu sheet in overlap configuration. The cross sections were etched by using 17 different reagents, including common Al-grade 2xxx etchants, Al-bronze etchants, and specific IMC etchants. A complete microstructural characterization, including the formation of intermetallic compounds, is presented. The experimental result showed that a clear distinction of metallurgic structures is possible, thus enabling a more detailed analysis of Al-Cu welds. It was found that etchants #09, #14, and #16 revealed best the four different intermetallic compounds θ-Al2Cu, η-AlCu, ζ-Al3Cu4, and γ-Al4Cu9. [less ▲]

An international case-vignette study to assess general practitioners’ willingness to deprescribe (LESS)

in Collins, Claire (Ed.) Abstract Book of the 87th EGPRN Meeting (2018, November 14)

Background: Globally, many oldest-old (>80 years of age) suffer from several chronic conditions and take multiple medications. Ideally, their general practitioners (GPs) regularly and systematically ... [more ▼]

Background: Globally, many oldest-old (>80 years of age) suffer from several chronic conditions and take multiple medications. Ideally, their general practitioners (GPs) regularly and systematically search for inappropriate medications and, if necessary, deprescribe those. However, deprescribing is challenging due to numerous barriers not only within patients, but also within GPs. Research questions: How does the willingness to deprescribe in oldest-old with polypharmacy differ in GPs from different countries? What factors do GPs in different contexts perceive as important for deprescribing? Method: We assess GPs' willingness to deprescribe and the factors GPs perceive to influence their deprescribing decisions in a cross-sectional survey using case-vignettes of oldest-old patients with polypharmacy. We approach GPs in 28 European countries as well as in Israel, Brazil and New Zealand through national coordinators, who administer the survey in their GP network. The case vignettes differ in how dependent patients are and whether or not they have a history of cardiovascular disease (CVD). For each case vignette, GPs are asked if and which medication they would deprescribe. GPs further rate to what extent pre-defined factors influence their deprescribe decisions. We will compare the willingness to deprescribe and the factors influencing deprescribing across countries. Multilevel models will be used to analyze the proportions of the deprescribed medications per case along the continuum of dependency and history of CVD and to analyze the factors perceived as influencing deprescribing decisions. Results: As of early-July 2018, the survey has been distributed in 14 countries and >650 responses have been returned. We will present first results at the conference. Conclusions: First, assessing GPs’ willingness to deprescribe and comparing the factors influencing GPs’ deprescribing decisions across countries will allow an understanding of the expected variation in the willingness to deprescribe across different contexts. Second, it will enable the tailoring of specific interventions that might facilitate deprescribing in oldest-old patients. Points for discussion: How can we explain differences across countries? How can the results be translated into practice in order to help GPs to optimize deprescribing practices? What factors could help GPs to implement deprescribing in oldest-old patients with polypharmacy? [less ▲]

Public roundtable with Arlette Farge

Scientific Conference (2018, November 14)

Persistent Identifiers. What? Why? How?

Speeches/Talks (2018)