Martin Luther University of Halle-Wittenberg

About: Martin Luther University of Halle-Wittenberg is a education organization based out in Halle, Germany. It is known for research contribution in the topics: Population & Liquid crystal. The organization has 20232 authors who have published 38773 publications receiving 965004 citations. The organization is also known as: MLU & University of Wittenberg.

Octopus, a computational framework for exploring light-driven phenomena and quantum dynamics in extended and finite systems

Abstract: Over the last few years, extraordinary advances in experimental and theoretical tools have allowed us to monitor and control matter at short time and atomic scales with a high degree of precision. An appealing and challenging route toward engineering materials with tailored properties is to find ways to design or selectively manipulate materials, especially at the quantum level. To this end, having a state-of-the-art ab initio computer simulation tool that enables a reliable and accurate simulation of light-induced changes in the physical and chemical properties of complex systems is of utmost importance. The first principles real-space-based Octopus project was born with that idea in mind, i.e., to provide a unique framework that allows us to describe non-equilibrium phenomena in molecular complexes, low dimensional materials, and extended systems by accounting for electronic, ionic, and photon quantum mechanical effects within a generalized time-dependent density functional theory. This article aims to present the new features that have been implemented over the last few years, including technical developments related to performance and massive parallelism. We also describe the major theoretical developments to address ultrafast light-driven processes, such as the new theoretical framework of quantum electrodynamics density-functional formalism for the description of novel light-matter hybrid states. Those advances, and others being released soon as part of the Octopus package, will allow the scientific community to simulate and characterize spatial and time-resolved spectroscopies, ultrafast phenomena in molecules and materials, and new emergent states of matter (quantum electrodynamical-materials).

Gut pathology and responses to the microsporidium Nosema ceranae in the honey bee Apis mellifera.

Abstract: The microsporidium Nosema ceranae is a newly prevalent parasite of the European honey bee (Apis mellifera). Although this parasite is presently spreading across the world into its novel host, the mechanisms by it which affects the bees and how bees respond are not well understood. We therefore performed an extensive characterization of the parasite effects at the molecular level by using genetic and biochemical tools. The transcriptome modifications at the midgut level were characterized seven days post-infection with tiling microarrays. Then we tested the bee midgut response to infection by measuring activity of antioxidant and detoxification enzymes (superoxide dismutases, glutathione peroxidases, glutathione reductase, and glutathione-S-transferase). At the gene-expression level, the bee midgut responded to N. ceranae infection by an increase in oxidative stress concurrent with the generation of antioxidant enzymes, defense and protective response specifically observed in the gut of mammals and insects. However, at the enzymatic level, the protective response was not confirmed, with only glutathione-S-transferase exhibiting a higher activity in infected bees. The oxidative stress was associated with a higher transcription of sugar transporter in the gut. Finally, a dramatic effect of the microsporidia infection was the inhibition of genes involved in the homeostasis and renewal of intestinal tissues (Wnt signaling pathway), a phenomenon that was confirmed at the histological level. This tissue degeneration and prevention of gut epithelium renewal may explain early bee death. In conclusion, our integrated approach not only gives new insights into the pathological effects of N. ceranae and the bee gut response, but also demonstrate that the honey bee gut is an interesting model system for studying host defense responses.

Stability and electronic properties of new inorganic perovskites from high-throughput ab initio calculations

Abstract: Using a high-throughput approach based on density functional theory, we perform an extensive study of possible ABX3 perovskites, where X is a non-metal and A and B span a large portion of the periodic table. We calculate the ternary phase diagram for each composition and we discuss the thermodynamic stability of perovskite phases. We find a large number of ABX3 perovskites, which are still absent from available databases, and which are stable with respect to decomposition into known ternary, binary or elementary phases. For these structures, we then calculate electronic band gaps, hole effective masses, and the spontaneous ferroelectric and magnetic polarization, which are relevant material properties for a number of specific applications in photovoltaics, transparent contacts, piezoelectrics, and magnetoelectrics. Some of our novel perovskites exhibit promising properties for applications.

Pattern of lymph node metastases in papillary thyroid carcinoma.

Abstract: Background Incidence and pattern of lymph node metastasis (LNM) were evaluated in 35 patients who underwent primary surgery for papillary thyroid carcinoma. Methods Total thyroidectomy with systematic cervicocentral lymphadenectomy was performed routinely. Additionally, 22 patients underwent lymphadenectomy of the ipsilateral cervicolateral compartment. Sternotomy was performed in four patients. Results Primary tumour status was: pT1, n = 7; pT2, n = 12; pT3, n = 4; pT4, n = 12. Twenty-four patients had LNM in the ipsilateral cervicocentral compartment (pT1, n = 2; pT2, n = 8; pT3, n = 4; pT4, n = 10). Nineteen had LNM in the ipsilateral cervicolateral compartment (pT1, n = 4; pT2, n = 6; pT3, n = 2; pT4, n = 7). Contralateral cervicocentral LNM was restricted to patients with pT3 tumours (n = 2) or pT4 tumours (n = 3). No patient had LNM in the contralateral cervicolateral compartment. Only one patient (pT3 tumour) had mediastinal LNM. Conclusion The cervicocentral compartment was most commonly involved with metastases, although the ipsilateral cervicolateral compartment was almost as often affected. In some patients ipsilateral cervicolateral LNM was present in the absence of cervicocentral LNM. Contralateral cervicolateral and upper mediastinal LNM, however, were rare. This study helps to plan radical surgery for papillary thyroid carcinoma. © 1998 British Journal of Surgery Society Ltd