Probing porosity in metals by electrical conductivity: Nanoscale experiments and multiscale simulations

Motivated by the significant influence of the underlying microstructure on the effective electrical properties of a material system and the desire to monitor defect evolution through non-destructive electrical characterisation, this contribution is concerned with a detailed study of conductivity changes caused by the presence of sub-microscale pores. Reducing the complexity of the material system, geometrically well-defined pore arrays are created by focused ion beam (FIB) milling in Cu thin films and characterised by 4-point probe electrical measurements. The experiment is designed such that it reduces to a (quasi-)one-dimensional electrical problem which is amenable to analytical techniques when invoking a computational homogenisation scheme to approximate the effective electrical properties of a given microstructure. The applicability of the proposed approach is shown in a first step by comparing simulation results for different pore volume fractions and pore shapes against their experimental counterparts. In a second step, a sensitivity analysis of the experimental data is carried out and the usefulness of the proposed modelling approach in interpreting the experimental data is demonstrated. In particular, the findings suggest that the proposed experimental method allows (at best) the determination of pore volume fractions with an accuracy of ±0.5%

Characterization of a protein of the plastid inner envelope having homology to animal inorganic phosphate, chloride and organic-anion transporters

A protein from Arabidopsis thaliana (L.) Heynh. showing homology to animal proteins of the NaPi-1 family, involved in the transport of inorganic phosphate, chloride, glutamate and sialic acid, has been characterized. This protein, named ANTR2 (for anion transporters) was shown by chloroplast subfractionation to be localized to the plastid inner envelope in both A. thaliana and Spinacia oleracea (L.). Immunolocalization revealed that ANTR2 was expressed in the leaf mesophyll cells as well as in the developing embryo at the upturned-U stage. Five additional homologues of ANTR2 are found in the Arabidopsis genome, of which one was shown by green fluorescent protein (GFP) fusion to be also located in the chloroplast. All ANTR proteins share homology to the animal NaPi-1 family, as well as to other organic-anion transporters that are members of the Anion:Cation Symporter (ACS) family, and share the main features of transporters from this family, including the presence of 12 putative transmembrane domains and of a 7-amino acid motif in the fourth putative transmembrane domain. ANTR2 thus represent a novel protein of the plastid inner envelope that is likely to be involved in anion transpor

Unveiling community patterns and trophic niches of tropical and temperate ants using an integrative framework of field data, stable isotopes and fatty acids

Background: The use and partitioning of trophic resources is a central aspect of community function. On the ground of tropical forests, dozens of ant species may be found together and ecological mechanisms should act to allow such coexistence. One hypothesis states that niche specialization is higher in the tropics, compared to temperate regions. However, trophic niches of most species are virtually unknown. Several techniques might be combined to study trophic niche, such as field observations, fatty acid analysis (FAA) and stable isotope analysis (SIA). In this work, we combine these three techniques to unveil partitioning of trophic resources in a tropical and a temperate community. We describe patterns of resource use, compare them between communities, and test correlation and complementarity of methods to unveil both community patterns and species’ niches. Methods: Resource use was assessed with seven kinds of bait representing natural resources available to ants. Neutral lipid fatty acid (NLFA) profiles, and δ15N and δ13C isotope signatures of the species were also obtained. Community patterns and comparisons were analyzed with clustering, correlations, multivariate analyses and interaction networks. Results: Resource use structure was similar in both communities. Niche breadths (H′) and network metrics (Q and H_2′) indicated similar levels of generalization between communities. A few species presented more specialized niches, such as Wasmannia auropunctata and Lasius fuliginosus. Stable isotope signatures and NLFA profiles also indicated high generalization, although the latter differed between communities, with temperate species having higher amounts of fat and proportions of C18:1n9. Bait use and NLFA profile similarities were correlated, as well as species’ specialization indices (d′) for the two methods. Similarities in δ^(15)N and bait use, and in δ^(13)C and NLFA profiles, were also correlated. Discussion: Our results agree with the recent view that specialization levels do not change with latitude or species richness. Partition of trophic resources alone does not explain species coexistence in these communities, and might act together with behavioral and environmental mechanisms. Temperate species presented NLFA patterns distinct from tropical ones, which may be related to environmental factors. All methods corresponded in their characterization of species’ niches to some extent, and were robust enough to detect differences even in highly generalized communities. However, their combination provides a more comprehensive picture of resource use, and it is particularly important to understand individual niches of species. FAA was applied here for the first time in ant ecology, and proved to be a valuable tool due to its combination of specificity and temporal representativeness. We propose that a framework combining field observations with chemical analysis is valuable to understand resource use in ant communities

Feilke revisited : 60 Stellenbesuche

Weitere Hrsg.: Thorsten Pohl, Sara Rezat, Torsten Steinhoff, Martin SteinseiferAnlässlich des 60. Geburtstags des Linguisten und Sprachdidaktikers Helmuth Feilke wurden Wegbegleiterinnen und Wegbegleiter gebeten, einzelne Stellen in seinen wissenschaftlichen Schriften erneut zu besuchen. Entstanden sind pointierte Kommentare, kurze wissenschaftliche Abhandlungen und Analysen, Varianten auch des kritischen und kontroversen Nach- und Weiterdenkens und Ansätze zur Neu- oder Re-Kontextualisierung. Je nach wissenschaftlicher Vita der Autorinnen und Autoren kann es sich um Stellen handeln, deren Rezeption zeitlich weit zurückliegt, oder um Passagen, die ganz aktuelle Fragen der eigenen Forschungsarbeit tangieren. Abgesehen davon, dass ein kurzes Format für die Beiträge gewählt und die Autorinnen und Autoren gebeten wurden, die ausgewählte Stelle knapp zu verorten und zu erläutern, war die Bearbeitungsform gänzlich freigestellt. So sind Texte in einer Bandbreite von pointierten Kommentaren, kurzen wissenschaftlichen Abhandlungen und Analysen, Varianten des Nach- und Weiterdenkens, Ansätze zur Neu- oder Re-Kontextualisierung bis hin zu Formen des kritischen Hinterfragens und der kontroversen Auseinandersetzung entstanden

The future of road transport

A perfect storm of new technologies and new business models is transforming not only our vehicles, but everything about how we get around, and how we live our lives. The JRC report “The future of road transport - Implications of automated, connected, low-carbon and shared mobility” looks at some main enablers of the transformation of road transport, such as data governance, infrastructures, communication technologies and cybersecurity, and legislation. It discusses the potential impacts on the economy, employment and skills, energy use and emissions, the sustainability of raw materials, democracy, privacy and social fairness, as well as on the urban context. It shows how the massive changes on the horizon represent an opportunity to move towards a transport system that is more efficient, safer, less polluting and more accessible to larger parts of society than the current one centred on car ownership. However, new transport technologies, on their own, won't spontaneously make our lives better without upgrading our transport systems and policies to the 21st century. The improvement of governance and the development of innovative mobility solutions will be crucial to ensure that the future of transport is cleaner and more equitable than its car-centred present.JRC.C.4-Sustainable Transpor

Micro-connectomics: probing the organization of neuronal networks at the cellular scale.

Defining the organizational principles of neuronal networks at the cellular scale, or micro-connectomics, is a key challenge of modern neuroscience. In this Review, we focus on graph theoretical parameters of micro-connectome topology, often informed by economical principles that conceptually originated with Ramón y Cajal's conservation laws. First, we summarize results from studies in intact small organisms and in samples from larger nervous systems. We then evaluate the evidence for an economical trade-off between biological cost and functional value in the organization of neuronal networks. Various results suggest that many aspects of neuronal network organization are indeed the outcome of competition between these two fundamental selection pressures.This work was supported by the National Institute of Health Research (NIHR) Cambridge Biomedical Research Centre.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by the Nature Publishing Group

Analysis of declarations in distance based road toll schemes

The main focus of the master thesis lies on developing a methodology to analyse the accuracy of toll declarations within a satellite based toll system. This methodology employs two different approaches to determine reasons why Toll Service Providers (TSP) deliver toll declarations that show charge inaccuracies. Both approaches are carried out to analyse the results of the ARENA project’s field test which was held in April 2010 to test On Board Unit (OBU) solutions for toll collection. In particular, the charge reports of companies that participated in the field test are analysed. An overview of satellite based tolling systems with regards to the design of the associated pricing lists and toll declaration requirements has shown that many differences among the tolling systems in Europe exist. In addition a practical analysis of the available test data is performed. The first approach is to use the delivered raw data from the compliance check reports to create a new set of charge reports. This set of newly created charge reports is then compared to the TSPs’ delivered charge reports and the known true charge report. Significant correlations between the TSP’s charge reports and the newly created ones are identified which lead to the conclusion that the raw data has been facilitated by the TSP to calculate the fees within the charge reports. The results of the comparison when applying the first approach to the ARENA test data prove that the reason for the inaccuracies does not lie in the wrong calculation of the fees according to the ARENA pricing list but lies within the raw GPS data itself. The second facilitated approach is to visualise the GPS data in ArcGIS in order to analyse the reported trajectories. Therefore the true route, the reported trajectory and data from a reference OBU is used as an input. The results of applying the second approach to the ARENA test results show that inaccuracies were caused by failing to collect GPS data during power outages. Furthermore it is determined that there were data management problems on the TSP side regarding the time stamps of the reported test data

Analysis of declarations in distance based road toll schemes

The main focus of the master thesis lies on developing a methodology to analyse the accuracy of toll declarations within a satellite based toll system. This methodology employs two different approaches to determine reasons why Toll Service Providers (TSP) deliver toll declarations that show charge inaccuracies. Both approaches are carried out to analyse the results of the ARENA project’s field test which was held in April 2010 to test On Board Unit (OBU) solutions for toll collection. In particular, the charge reports of companies that participated in the field test are analysed. An overview of satellite based tolling systems with regards to the design of the associated pricing lists and toll declaration requirements has shown that many differences among the tolling systems in Europe exist. In addition a practical analysis of the available test data is performed. The first approach is to use the delivered raw data from the compliance check reports to create a new set of charge reports. This set of newly created charge reports is then compared to the TSPs’ delivered charge reports and the known true charge report. Significant correlations between the TSP’s charge reports and the newly created ones are identified which lead to the conclusion that the raw data has been facilitated by the TSP to calculate the fees within the charge reports. The results of the comparison when applying the first approach to the ARENA test data prove that the reason for the inaccuracies does not lie in the wrong calculation of the fees according to the ARENA pricing list but lies within the raw GPS data itself. The second facilitated approach is to visualise the GPS data in ArcGIS in order to analyse the reported trajectories. Therefore the true route, the reported trajectory and data from a reference OBU is used as an input. The results of applying the second approach to the ARENA test results show that inaccuracies were caused by failing to collect GPS data during power outages. Furthermore it is determined that there were data management problems on the TSP side regarding the time stamps of the reported test data

Conjugates of methylated cyclodextrin derivatives and hydroxyethyl starch (HES): Synthesis, cytotoxicity and inclusion of anaesthetic actives

The mono-6-deoxy-6-azides of 2,6-di-O-methyl-beta-cyclodextrin (DIMEB) and randomly methylated-beta-cyclodextrin (RAMEB) were conjugated to propargylated hydroxyethyl starch (HES) by Cu+-catalysed [2 + 3] cycloaddition. The resulting water soluble polymers showed lower critical solution temperatures (LCST) at 52.5 degrees C (DIMEB-HES) and 84.5 degrees C (RAMEB-HES), respectively. LCST phase separations could be completely avoided by the introduction of a small amount of carboxylate groups at the HES backbone. The methylated CDs conjugated to the HES backbone exhibited significantly lower cytotoxicities than the corresponding monomeric CD derivatives. Since the binding potentials of these CD conjugates were very high, they are promising candidates for new oral dosage forms of anaesthetic actives