Dynamics of leaf-and root-specific biomarkers during 1-year of litter decomposition

Root-specific and leaf-specific biomarkers have been used for decades to identify the origin of organic materials in soils and sediments. However, quantitative approaches require appropriate knowledge about the fate of these indicator molecules during degradation. To clarify this issue, we performed a 1-year incubation experiment with fine root and leaf material of six temperate tree species: European ash (Fraxinus excelsior), European beech (Fagus sylvatica), Oak spec. (Quercus spec.), Linden spec. (Tilia spec.), Norway spruce (Picea abies) and Scots pine (Pinus sylvatica). Only one molecule, x,16-dihydroxy hexadecanoic acid (x,16-C16), could be validated as a general leaf-specific biomarker for the set of all species. For roots, no general root biomarker was found. Ester-bound tricosanol (C23-OH) could be validated for five out of six species; 20-hydroxy eicosanoic acid (ωC20) could be validated for four out of six species, leaving Norway spruce without a suitable root biomarker. The results of this study suggest that the validity of leaf- and root-derived ester-bound lipids as biomarkers is highly species dependent and does not always coincide with previous findings. Concentrations of root- and leaf-derived ester-bound lipids did not stay constant within 1 year of degradation and changed without a linear trend. The change of concentrations seems to be highly species dependent. This might be due to a different structure and arrangement of the individual monomers in cutin and suberin per species, and, therefore, a different accessibility of bond cleaving enzymes. The usefulness of root and leaf biomarkers is context dependent. Our results suggest that general assumptions about litter input to forest soils solely based on biomarker analysis have to be considered carefully

<i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data

Neutrino oscillation studies with IceCube-DeepCore

AbstractIceCube, a gigaton-scale neutrino detector located at the South Pole, was primarily designed to search for astrophysical neutrinos with energies of PeV and higher. This goal has been achieved with the detection of the highest energy neutrinos to date. At the other end of the energy spectrum, the DeepCore extension lowers the energy threshold of the detector to approximately 10 GeV and opens the door for oscillation studies using atmospheric neutrinos. An analysis of the disappearance of these neutrinos has been completed, with the results produced being complementary with dedicated oscillation experiments. Following a review of the detector principle and performance, the method used to make these calculations, as well as the results, is detailed. Finally, the future prospects of IceCube-DeepCore and the next generation of neutrino experiments at the South Pole (IceCube-Gen2, specifically the PINGU sub-detector) are briefly discussed

Stability of needle- and root-derived biomarkers during litter decomposition

Background and aims: Plant‐derived, ester‐bound substituted fatty acids have been used for decades as biomarkers to identify input of plant materials in sediments and soils. However, the long‐term decomposition patterns of these biomarker compounds under natural conditions are not well understood, although this is a basic prerequisite for quantitative biomarker applications. Methods: For this study, we analyzed the decomposition patterns of root‐ and needle‐specific compounds of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) in a litterbag study conducted over 3 years. Samples were analyzed by methanolic KOH extraction with previous removal of free extractable lipids. Results: The concentrations of most detectable compounds had decreased after three years of incubation. The observed changes of concentrations followed a non‐linear path and cannot be explained by microbial uptake and metabolism alone. Other factors controlling the breakdown of ester‐bound lipids, like lipid oxidation must play a role. Between similar plant parts and different plant parts of the same species, the observed degradation patterns were heterogeneous. The estimated ratio of remaining root and needle biomass that may arise with the choice of a particular biomarker varies in this study between 0.6 and 40 times after three years. Conclusion: This range of variation does not allow reliable conclusions about the contribution of roots and needles to decomposed organic matter based on biomarkers ratios

The FTMPS-Project: Design and Implementation of Fault-Tolerance Techniques for Massively Parallel Systems

The FTMPS-project provides a solution to the need for faulttolerance in large systems . A complete fault-tolerance approach is developed and being implemented . The built-in hardware error-detection features combined with software error-detection techniques provide a high coverage of transient as well as perananent failures . Combined with the diagnosis software, the necessary information for the OSS (statistics and visualisation) and the possibly reconfigm-ation is collected . Backward error recovery based on checkpointing and rollback, is implementedSupported by the EC as ESPRIT-project 673