1,725 research outputs found

    Environmental conditions of a salt-marsh biodiversity experiment on the island of Spiekeroog (Germany)

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    Field experiments investigating biodiversity and ecosystem functioning require the observation of abiotic parameters, especially when carried out in the intertidal zone. An experiment for biodiversity‚Äďecosystem functioning was set up in the intertidal zone of the back-barrier salt marsh of Spiekeroog Island in the German Bight. Here, we report the accompanying instrumentation, maintenance, data acquisition, data handling and data quality control as well as monitoring results observed over a continuous period from September 2014 to April 2017. Time series of abiotic conditions were measured at several sites in the vicinity of newly built experimental salt-marsh islands on the tidal flat. Meteorological measurements were conducted from a weather station (WS, https://doi.org/10.1594/PANGAEA.870988), oceanographic conditions were sampled through a bottom-mounted recording current meter (RCM, https://doi.org/10.1594/PANGAEA.877265) and a bottom-mounted tide and wave recorder (TWR, https://doi.org/10.1594/PANGAEA.877258). Tide data are essential in calculating flooding duration and flooding frequency with respect to different salt-marsh elevation zones. Data loggers (DL) for measuring the water level (DL-W, https://doi.org/10.1594/PANGAEA.877267), temperature (DL-T, https://doi.org/10.1594/PANGAEA.877257), light intensity (DL-L, https://doi.org/10.1594/PANGAEA.877256) and conductivity (DL-C, https://doi.org/10.1594/PANGAEA.877266) were deployed at different elevational zones on the experimental islands and the investigated salt-marsh plots. A data availability of 80% for 17 out of 23 sensors was achieved. Results showed the influence of seasonal and tidal dynamics on the experimental islands. Nearby salt-marsh plots exhibited some differences, e.g., in temperature dynamics. Thus, a consistent, multi-parameter, long-term dataset is available as a basis for further biodiversity and ecosystem functioning studies

    Outlier robust corner-preserving methods for reconstructing noisy images

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    The ability to remove a large amount of noise and the ability to preserve most structure are desirable properties of an image smoother. Unfortunately, they usually seem to be at odds with each other; one can only improve one property at the cost of the other. By combining M-smoothing and least-squares-trimming, the TM-smoother is introduced as a means to unify corner-preserving properties and outlier robustness. To identify edge- and corner-preserving properties, a new theory based on differential geometry is developed. Further, robustness concepts are transferred to image processing. In two examples, the TM-smoother outperforms other corner-preserving smoothers. A software package containing both the TM- and the M-smoother can be downloaded from the Internet.Comment: Published at http://dx.doi.org/10.1214/009053606000001109 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Outcome of renal grafts after simultaneous kidney/ pancreas transplantation

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    Nineteen patients with endstage renal failure due to Type 1 (insulin-dependent) diabetes mellitus received simultaneous pancreas/kidney transplants using bladder drainage technique. Another group of 25 Type 1 diabetic patients received pancreas/kidney transplants by the duct occlusion technique. We observed a higher incidence of rejection episodes in the patients of the bladder drainage group than those in the duct occlusion group, 14 of 19 patients (74%) vs 7 of 25 (28%) respectively. Anti CD3 antibodies (Orthoclone, OKT3) as a part of induction treatment was used more often in the bladder drainage group (58%) than in the control group (20%)

    Proteoglykane und die Verpackung von Exportproteinen: Interaction von Serglycin und ZG 16 in den Zymogengranula des exokrinen Rattenpankreas

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    In Vorarbeiten konnte das Proteoglykan Serglycin in den Zymogengranula der Azinuszellen des exokrinen Rattenpankreas als Bindungspartner des sekretorischen Lektins ZG 16 identifiziert werden. Ferner konnte gezeigt werden, dass das korrekt glykosylierte Serglycin f√ľr die Sortierung von Zymogenen in die Granula n√∂tig ist (Biederbick et al., 2003). Ziel dieser Arbeit war es, die Interaktion zwischen dem √ľberwiegend membranst√§ndigen ZG 16 und Serglycin n√§her zu analysieren, um Aufschluss √ľber Mechanismen der Verpackung und Sortierung der Zymogene zu erhalten. Dar√ľber hinaus sollten m√∂gliche weitere Proteoglykane aus dem Inhalt der Zymogengranula isoliert werden. Es wurden folgende Ergebnisse erzielt: 1. Durch Klonierung und Expression der unverzuckerten, rekombinanten N- und C-terminalen Abschnitte des Serglycin und deren Einsatz in Bindungsstudien (Co-Immunopr√§zipitation, GST-pull-down, Ligandenblots und Crosslinkexperimenten) wurde festgestellt, dass die Interaktion zwischen ZG 16 und Serglycin √ľber den unverzuckerten N-terminalen Bereich (SGN) durch zuckerunabh√§ngige Protein-Protein-Wechselwirkungen erfolgt. 2. Die Bindungssequenz des Serglycin an das ZG 16 konnte durch Herstellung verschiedener Punkt- und Deletionsmutanten des N-terminalen Bereichs SGN und deren Verwendung in Bindungsstudien auf die 9 N-Terminus nahen Aminos√§uren ARYQWVRCK eingegrenzt werden. 3. Bei der Analyse der hypothetischen Sekund√§rstruktur des Serglycin, die mit Hilfe des ExPASy Molecular Biology Server erstellt wurde, gab es sehr starke Hinweise darauf, dass das Bindungsmotiv des Serglycin an das ZG 16 ein b-Faltblatt darstellt. Diese Daten zeigen, dass Serglycin √ľber den N-terminalen unverzuckerten Abschnitt eine Protein-Protein-Interaktion mit dem sekretorischen Lektin ZG 16 macht. √úber diese Interaktion werden das Serglycin und √ľber seine Glykosaminoglykan-Ketten assoziierte Zymogene an die Zymogengranulamembran gebunden. Diese Wechselwirkung stellt einen Sortierungsmechanismus f√ľr die Zymogene in die Granula dar. 4. F√ľr das Vorhandensein weiterer Proteoglykane im Inhalt der Zymogengranula (ZGI) konnten nur indirekte Hinweise gefunden werden. Im Blyscan-Assay, einer F√§llung, die spezifisch f√ľr Proteoglykane ist, konnten durch Extinktionsmessung Proteoglykane nachgewiesen werden. Die gr√∂√üte Extinktion wurde nach Vorbehandlung des ZGI mit NaHCO3 erhalten. 5. Die Zymogene scheinen mit Proteoglykanen assoziiert zu sein. Durch diese Interaktion gelangt ein Teil der Zymogene noch nach NaHCO3-Behandlung von ZGI und anschlie√üender Blyscan- oder Wesself√§llung in das Blyscanpellet, bzw. in die organische Phase der Wesself√§llung. Durch EGTA-Inkubation von ZGI kann diese Interaktion zwischen Proteoglykanen und Zymogenen aufgehoben werden. Hier erscheinen keine Zymogene im Blyscanpellet oder der organischen Phase der Wesself√§llung

    Diversity and community biomass depend on dispersal and disturbance in microalgal communities

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    The evidence for species diversity effects on ecosystem functions is mainly based on studies not explicitly addressing local or regional processes regulating coexistence or the importance of community structure in terms of species evenness. In experimental communities of marine benthic microalgae, we altered the successional stages and thus the strength of local species interactions by manipulating rates of dispersal and disturbance. The treatments altered realized species richness, evenness and community biomass. For species richness, dispersal mattered only at high disturbance rates; when opening new space, dispersal led to maximized richness at intermediate dispersal rates. Evenness, in contrast, decreased with dispersal at low or no disturbance, i.e. at late successional stages. Community biomass showed a nonlinear hump-shaped response to increasing dispersal at all disturbance levels.We found a positive correlation between richness and biomass at early succession, and a strong negative correlation between evenness and biomass at late succession. In early succession both community biomass and richness depend directly on dispersal from the regional pool, whereas the late successional pattern shows that if interactions allow the most productive species to become dominant, diverting resources from this species (i.e. higher evenness) reduces production. Our study emphasizes the difference in biodiversity‚Äďfunction relationships over time, as different mechanisms contribute to the regulation of richness and evenness in early and late successional stages

    Eliminating Recursion from Monadic Datalog Programs on Trees

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    We study the problem of eliminating recursion from monadic datalog programs on trees with an infinite set of labels. We show that the boundedness problem, i.e., determining whether a datalog program is equivalent to some nonrecursive one is undecidable but the decidability is regained if the descendant relation is disallowed. Under similar restrictions we obtain decidability of the problem of equivalence to a given nonrecursive program. We investigate the connection between these two problems in more detail

    On consistency of redescending M-kernel smoothers

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    Abstract M-estimators and M-kernel estimators with a redescending Ōą-function are not in general consistent. This is often handled by means of coupling the estimator to a consistent one. Coupling the estimator to the (inconsistent) starting point improves the jump preserving properties. However, the consistency depends heavily on the shape of the density of the residuals. This paper shows inconsistency under convenient conditions as well as consistency-even at jump points-under somewhat stronger conditions

    Hydration-Scanning Tunneling Microscopy as a Reliable Method for Imaging Biological Specimens and Hydrophilic Insulators

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    The recently discovered high lateral conductivity of molecularly thin adsorbed water films enables investigation of biological specimens, and even of surfaces of hydrophilic insulators by scanning tunneling microscopy (STM). Here we demonstrate the capabilities of this method, which we call hydration-STM (HSTM), with images of various specimens taken in humid atmosphere: We obtained images of a glass coverslip, collagen molecules, tobacco mosaic virus, lipid bilayers and cryosectioned bovine achilles tendon on mica. To elucidate the physical mechanism of this conduction phenomenon we recorded current-voltage curves on hydrated mica. This revealed a basically ohmic behavior of the J-V curves without a threshold voltage to activate the current transport and indicates that electrochemistry probably does not dominate the surface conductivity. We assume that the conduction mechanism is due to structuring of water at the surface
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