Leibniz University of Hanover

About: Leibniz University of Hanover is a education organization based out in Hanover, Niedersachsen, Germany. It is known for research contribution in the topics: Finite element method & Population. The organization has 14283 authors who have published 29845 publications receiving 682152 citations.

Li self-diffusion in garnet-type Li 7 La 3 Zr 2 O 12 as probed directly by diffusion-induced Li 7 spin-lattice relaxation NMR spectroscopy

Abstract: Li self-diffusion in garnet-type Li${}_{7}$La${}_{3}$Zr${}_{2}$O${}_{12}$, crystallizing with tetragonal symmetry at room temperature, is measured by temperature-variable $^{7}\mathrm{Li}$ spin-spin as well as spin-lattice relaxation (SLR) nuclear magnetic resonance (NMR) spectroscopy. The SLR NMR rates which were recorded in both the laboratory and the rotating frame of reference pass through characteristic diffusion-induced rate peaks allowing for the direct determination of Li jump rates ${\ensuremath{\tau}}^{\ensuremath{-}1}$, which can be directly converted into self-diffusion coefficients ${D}_{\mathrm{sd}}$. The NMR results are compared with those obtained from electrical impedance spectroscopy measurements carried out in a large temperature and wide frequency range. Taken together, the long-range diffusion process, being mainly responsible for ionic conduction at ambient temperature, is characterized by an activation energy of approximately 0.5 eV, with ${\ensuremath{\tau}}_{0}^{\ensuremath{-}1}\ensuremath{\approx}1\ifmmode\times\else\texttimes\fi{}{10}^{14}$ ${\mathrm{s}}^{\ensuremath{-}1}$ being the pre-exponential factor of the underlying Arrhenius relation.

Simulating the Multipath Channel With a Reverberation Chamber: Application to Bit Error Rate Measurements

Abstract: We illustrate the use of the reverberation chamber to simulate fixed wireless propagation environments including effects such as narrowband fading and Doppler spread. These effects have a strong impact on the quality of the wireless channel and the ability of a receiver to decode a digitally modulated signal. Different channel characteristics such as power delay profile and RMS delay spread are varied inside the chamber by incorporating various amounts of absorbing material. In order to illustrate the impact of the chamber configuration on the quality of a wireless communication channel, bit error rate measurements are performed inside the reverberation chamber for different loadings, symbol rates, and paddle speeds; the results are discussed. Measured results acquired inside a chamber are compared with those obtained both in an actual industrial environment and in an office.

Defining the Protein Complex Proteome of Plant Mitochondria

Abstract: A classical approach, protein separation by two-dimensional blue native/sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was combined with tandem mass spectrometry and up-to-date computer technology to characterize the mitochondrial “protein complex proteome” of Arabidopsis (Arabidopsis thaliana) in so far unrivaled depth. We further developed the novel GelMap software package to annotate and evaluate two-dimensional blue native/sodium dodecyl sulfate gels. The software allows (1) annotation of proteins according to functional and structural correlations (e.g. subunits of a distinct protein complex), (2) assignment of comprehensive protein identification lists to individual gel spots, and thereby (3) selective display of protein complexes of low abundance. In total, 471 distinct proteins were identified by mass spectrometry, several of which form part of at least 35 different mitochondrial protein complexes. To our knowledge, numerous protein complexes were described for the first time (e.g. complexes including pentatricopeptide repeat proteins involved in nucleic acid metabolism). Discovery of further protein complexes within our data set is open to everybody via the public GelMap portal at www.gelmap.de/arabidopsis_mito.

Setting upper limits on the strength of periodic gravitational waves from PSR J1939+2134 using the first science data from the GEO 600 and LIGO detectors

Abstract: Data collected by the GEO 600 and LIGO interferometric gravitational wave detectors during their first observational science run were searched for continuous gravitational waves from the pulsar J1939+2134 at twice its rotation frequency. Two independent analysis methods were used and are demonstrated in this paper: a frequency domain method and a time domain method. Both achieve consistent null results, placing new upper limits on the strength of the pulsar’s gravitational wave emission. A model emission mechanism is used to interpret the limits as a constraint on the pulsar’s equatorial ellipticity.

Regional Dimensions of Entrepreneurship

Abstract: It was Maryann Feldman who first characterized entrepreneurship as a predominantly “regional event.” While the spatial, or more specifically, the regional perspective has long been ignored by entrepreneurship research, this changed in recent years. Globalization and regionalization (as two sides of the same coin), the new role of small firms in general for regional growth, and the increasing relevance of entrepreneurship policies drew several researchers’ attention to the regional causes and consequences of entrepreneurial activities.This review assesses several theoretical arguments supporting the idea that entrepreneurial activities as well as entrepreneurial success (measured, for example, in terms of survival rates) are influenced in many cases by the attributes of the region (defined as a sub-national spatial unit) where the potential founder and the real founder of a firm was or actually is located. While there are still significant gaps in research in terms of adequate regional theories of entrepreneurship, a great number of empirical studies have been undertaken in the past decade to explore the interdependent relationship between regional environment on the one hand and entrepreneurial activities and success on the other. The results are quite heterogeneous, as are the environments between regions within and especially between countries. However, it is rather clear now that the regional environment as an important context variable must not be ignored any further when exploring the determinants of firm creation and of new-firm growth.