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In order to predict which ecosystem functions are most at risk from biodiversity loss, meta-analyses have generalised results from biodiversity experiments over different sites and ecosystem types. In contrast, comparing the strength of biodiversity effects across a large number of ecosystem processes measured in a single experiment permits more direct comparisons. Here, we present an analysis of 418 separate measures of 38 ecosystem processes. Overall, 45 % of processes were significantly affected by plant species richness, suggesting that, while diversity affects a large number of processes not all respond to biodiversity. We therefore compared the strength of plant diversity effects between different categories of ecosystem processes, grouping processes according to the year of measurement, their biogeochemical cycle, trophic level and compartment (above- or belowground) and according to whether they were measures of biodiversity or other ecosystem processes, biotic or abiotic and static or dynamic. Overall, and for several individual processes, we found that biodiversity effects became stronger over time. Measures of the carbon cycle were also affected more strongly by plant species richness than were the measures associated with the nitrogen cycle. Further, we found greater plant species richness effects on measures of biodiversity than on other processes. The differential effects of plant diversity on the various types of ecosystem processes indicate that future research and political effort should shift from a general debate about whether biodiversity loss impairs ecosystem functions to focussing on the specific functions of interest and ways to preserve them individually or in combination.
On the ALMA observability of nascent massive multiple systems formed by gravitational instability
(2019)
Massive young stellar objects (MYSOs) form during the collapse of high-mass pre-stellar cores, where infalling molecular material is accreted through a centrifugally balanced accretion disc that is subject to efficient gravitational instabilities. In the resulting fragmented accretion disc of the MYSO, gaseous clumps and low-mass stellar companions can form, which will influence the future evolution of massive protostars in the Hertzsprung-Russell diagram. We perform dust continuum radiative transfer calculations and compute synthetic images of disc structures modelled by the gravito-radiation-hydrodynamics simulation of a forming MYSO, in order to investigate the Atacama Large Millimeter/submillimeter Array (alma) observability of circumstellar gaseous clumps and forming multiple systems. Both spiral arms and gaseous clumps located at similar or equal to a few from the protostar can be resolved by interferometric alma Cycle 7 C43-8 and C43-10 observations at band 6 (), using a maximal 0.015 aracsec beam angular resolution and at least exposure time for sources at distances of . Our study shows that substructures are observable regardless of their viewing geometry or can be inferred in the case of an edge-viewed disc. The observation probability of the clumps increases with the gradually increasing efficiency of gravitational instability at work as the disc evolves. As a consequence, large discs around MYSOs close to the zero-age-main-sequence line exhibit more substructures than at the end of the gravitational collapse. Our results motivate further observational campaigns devoted to the close surroundings of the massive protostars S255IR-NIRS3 and NGC 6334I-MM1, whose recent outbursts are a probable signature of disc fragmentation and accretion variability.
Denkmalentdeckungen
(2007)
»Wenn du reisen willst, mußt du die Geschichte dieses Landes kennen und lieben. Das ist ganz unerläßlich. [...] Wag’ es getrost und du wirst es nicht bereuen. Eigentümliche Freuden und Genüsse werden dich begleiten. Du wirst Entdeckungen machen, denn überall wohin du kommst, wirst du, vom Touristenstandpunkt aus, eintreten wie in ›jungfräuliches Land‹. Du wirst Klosterruinen begegnen, von deren Existenz höchstens die nächste Stadt eine leise Kenntnis hatte; du wirst inmitten alter Dorfkirchen, deren zerbröckelter Schindelturm nur auf Elend deutete, große Wandbilder oder in den treppenlosen Grüften reiche Kupfersärge mit Kruzifix und vergoldeten Wappenschildern finden; du wirst Schlachtfelder überschreiten, Wendenkirchhöfe, Heidengräber, von denen die Menschen nichts mehr wissen.«
Die in diesem Bildband gesammelten »Denkmalentdeckungen« verstehen sich als Einladung zu einer Reise durch das Land Brandenburg. Theodor Fontane hatte für ein solches Unternehmen genau den richtigen Blick, als er in seinen »Wanderungen durch die Mark Brandenburg« 1864 diese Sätze schrieb. Auch heute noch sollten wir seiner Anregung zu Begegnungen mit der Geschichte und der Kunstgeschichte des Landes folgen, die uns im Dialog der Kulturen und der Zeiten eine Standortbestimmung in der Gegenwart und eine Orientierung für die Zukunft zugleich bietet.
The prototypical photoinduced dissociation of Fe(CO)(5) in the gas phase is used to test time-resolved x-ray photoelectron spectroscopy for studying photochemical reactions. Upon one-photon excitation at 266 nm, Fe(CO)(5) successively dissociates to Fe(CO)(4) and Fe(CO)(3) along a pathway where both fragments retain the singlet multiplicity of Fe(CO)(5). The x-ray free-electron laser FLASH is used to probe the reaction intermediates Fe(CO)(4) and Fe(CO)(3) with time-resolved valence and core-level photoelectron spectroscopy, and experimental results are interpreted with ab initio quantum chemical calculations. Changes in the valence photoelectron spectra are shown to reflect changes in the valenceorbital interactions upon Fe-CO dissociation, thereby validating fundamental theoretical concepts in Fe-CO bonding. Chemical shifts of CO 3 sigma inner-valence and Fe 3 sigma core-level binding energies are shown to correlate with changes in the coordination number of the Fe center. We interpret this with coordination-dependent charge localization and core-hole screening based on calculated changes in electron densities upon core-hole creation in the final ionic states. This extends the established capabilities of steady-state electron spectroscopy for chemical analysis to time-resolved investigations. It could also serve as a benchmark for howcharge and spin density changes in molecular dissociation and excited-state dynamics are expressed in valence and core-level photoelectron spectroscopy. Published by AIP Publishing.
In nature, the cellular environment of DNA includes not only water and ions, but also other components and co-solutes, which can exert both stabilizing and destabilizing effects on particular oligonucleotide conformations. Among them, ectoine, known as an important osmoprotectant organic co-solute in a broad range of pharmaceutical products, turns out to be of particular relevance. In this article, we study the influence of ectoine on a short single-stranded DNA fragment and on double-stranded helical B-DNA in aqueous solution by means of atomistic molecular dynamics (MD) simulations in combination with molecular theories of solution. Our results demonstrate a conformation-dependent binding behavior of ectoine, which favors the unfolded state of DNA by a combination of electrostatic and dispersion interactions. In conjunction with the Kirkwood-Buff theory, we introduce a simple framework to compute the influence of ectoine on the DNA melting temperature. Our findings reveal a significant linear decrease of the melting temperature with increasing ectoine concentration, which is found to be in qualitative agreement with results from denaturation experiments. The outcomes of our computer simulations provide a detailed mechanistic rationale for the surprising destabilizing influence of ectoine on distinct DNA structures.
Development of a multiple-chambered heart from the linear heart tube is inherently linked to cardiac looping. Although many molecular factors regulating the process of cardiac chamber ballooning have been identified, the cellular mechanisms underlying the chamber formation remain unclear. Here, we demonstrate that cardiac chambers remodel by cell neighbour exchange of cardiomyocytes guided by the planar cell polarity (PCP) pathway triggered by two non-canonical Wnt ligands, Wnt5b and Wnt11. We find that PCP signalling coordinates the localisation of actomyosin activity, and thus the efficiency of cell neighbour exchange. On a tissue-scale, PCP signalling planar-polarises tissue tension by restricting the actomyosin contractility to the apical membranes of outflow tract cells. The tissue-scale polarisation of actomyosin contractility is required for cardiac looping that occurs concurrently with chamber ballooning. Taken together, our data reveal that instructive PCP signals couple cardiac chamber expansion with cardiac looping through the organ-scale polarisation of actomyosin-based tissue tension.
Molecular rods consisting of a hydrophobic backbone and terminally varying functional groups have been synthesized for applications for the functionalization of membranes. In the present study, we employ a spin-labeled analogue of a recently described new class of molecular rods to characterize their dynamic interactions with membranes. By using the different approaches of ESR and NMR spectroscopy, we show that the spin moiety of the membrane-embedded spin-labeled rod is localized in the upper chain/glycerol region of membranes of different compositions. The rod is embedded within the membrane in a tilted orientation to adjust for the varying hydrophobic thicknesses of these bilayers. This orientation does not perturb the membrane structure. The water solubility of the rod is increased significantly in the presence of certain cyclodextrins. These cyclodextrins also allow the rods to be extracted from the membrane and incorporated into preformed membranes. The latter will improve the future applications of these rods in cellular systems as stable membrane-associated anchors for the functionalization of membrane surfaces.
We prove the hitherto hypothesized sequential dissociation of Fe(CO)(5) in the gas phase upon photoexcitation at 266 nm via a singlet pathway with time-resolved valence and core-level photoelectron spectroscopy with an x-ray free-electron laser. Valence photoelectron spectra are used to identify free CO molecules and to determine the time constants of stepwise dissociation to Fe(CO)(4) within the temporal resolution of the experiment and further to Fe(CO)(3) within 3 ps. Fe 3p core-level photoelectron spectra directly reflect the singlet spin state of the Fe center in Fe(CO)(5), Fe(CO)(4), and Fe(CO)(3) showing that the dissociation exclusively occurs along a singlet pathway without triplet-state contribution. Our results are important for assessing intra- and intermolecular relaxation processes in the photodissociation dynamics of the prototypical Fe(CO)(5) complex in the gas phase and in solution, and they establish time-resolved core-level photoelectron spectroscopy as a powerful tool for determining the multiplicity of transition metals in photochemical reactions of coordination complexes. Published by AIP Publishing.
Development of a multiple-chambered heart from the linear heart tube is inherently linked to cardiac looping. Although many molecular factors regulating the process of cardiac chamber ballooning have been identified, the cellular mechanisms underlying the chamber formation remain unclear. Here, we demonstrate that cardiac chambers remodel by cell neighbour exchange of cardiomyocytes guided by the planar cell polarity (PCP) pathway triggered by two non-canonical Wnt ligands, Wnt5b and Wnt11. We find that PCP signalling coordinates the localisation of actomyosin activity, and thus the efficiency of cell neighbour exchange. On a tissue-scale, PCP signalling planar-polarises tissue tension by restricting the actomyosin contractility to the apical membranes of outflow tract cells. The tissue-scale polarisation of actomyosin contractility is required for cardiac looping that occurs concurrently with chamber ballooning. Taken together, our data reveal that instructive PCP signals couple cardiac chamber expansion with cardiac looping through the organ-scale polarisation of actomyosin-based tissue tension.
Das Herbsttreffen Patholinguistik wird seit 2007 jährlich vom Verband für Patholinguistik e.V. (vpl) durchgeführt. Das 7. Herbsttreffen mit dem Schwerpunktthema "Hören – Zuhören – Dazugehören: Sprachtherapie bei Hörstörungen und Cochlea-Implantat" fand am 16.11.2013 in Potsdam statt. Der vorliegende Tagungsband beinhaltet die sechs Vorträge zum Schwerpunktthema aus verschiedenen Perspektiven: der medizinischen, der therapeutischen, der wissenschaftlichen sowie der von Betroffenen. Weiterhin sind die Beiträge der Posterpräsentationen zu Themen der sprachtherapeutischen Forschung und Praxis abgedruckt.