Vulkanmonitoring mittels bistatischer TanDEM-X SAR-Interferometrie

Seit 2011 untersuchen wir am geodätischen Institut die Eignung der innovativen bistatischen Satellitenmission TanDEM-X für das Monitoring aktiver Vulkane. Die TanDEM-X-Mission besteht aus den zwei nahezu identischen Radarsatelliten TerraSAR-X und TanDEM-X, die im engen Helix-Formationsflug als großes, Single-Pass SAR-Interferometer mit regulierbarer senkrechter Basislinie agieren. Das Hauptziel der Satellitenmission bestand in der Generierung eines globalen digitalen Elevationsmodells mit einer bisher noch nicht erreichten Auflösung entsprechend der HRTI-3 (High-Resolution Terrain Information) Spezifizierung oder besser. Im Gegensatz zur SRTM-Mission handelt es sich bei der TanDEM-X-Mission erstmalig um wiederkehrende Überflüge mit einem Wiederholintervall von elf Tagen. Die Differenzbildung digitaler Geländemodelle aus wiederholten Überflügen über dasselbe Gebiet hat sich als sehr geeignet erwiesen, um topographische Änderungen aktiver Vulkane während Eruptionen zu messen. Insgesamt wurden Untersuchungen an sechs verschiedenen Vulkanen durchgeführt und es konnten topographische und volumetrische Änderungen durch verschiedene Arten vulkanischer Aktivität gemessen werden. Diese Informationen bilden – zusammen mit anderen vulkanologischen Parametern – eine wichtige Grundlage für weitere vulkanologische Analysen hinsichtlich des Eruptions- und Gefährdungspotentials aktiver Vulkane

Volcano monitoring with bistatic TanDEM-X SAR interferometry

Das Ziel der Dissertation ist die Untersuchung der Nutzbarkeit der Daten der TanDEM-X-Satellitenmission in der Vulkanforschung. Dabei wird die Topographie vor, während und nach einem vulkanologischen Ereignis abgebildet. Anhand einer differentiellen Analyse der abgeleiteten DEMs können topographische und volumetrische Änderungen quantifiziert werden. Als Untersuchungsgebiete dienen der Merapi in Indonesien, der Volcán de Colima in Mexico und der Tolbachik in Kamtschatka, Russland

A Diamond-Photonics Platform Based on Silicon-Vacancy Centers in a Single Crystal Diamond Membrane and a Fiber-Cavity

We realize a potential platform for an efficient spin-photon interface, namely negatively-charged silicon-vacancy centers in a diamond membrane coupled to the mode of a fully-tunable, fiber-based, optical resonator. We demonstrate that introducing the thin ($\sim 200 \, \text{nm}$), single crystal diamond membrane into the mode of the resonator does not change the cavity properties, which is one of the crucial points for an efficient spin-photon interface. In particular, we observe constantly high Finesse values of up to $3000$ and a linear dispersion in the presence of the membrane. We observe cavity-coupled fluorescence froman ensemble of SiV$^{-}$ centers with an enhancement factor of $\sim 1.9$. Furthermore from our investigations we extract the ensemble absorption and extrapolate an absorption cross section of $(2.9 \, \pm \, 2) \, \cdot \, 10^{-12} \, \text{cm}^{2}$ for a single SiV$^{-}$ center, much higher than previously reported.Comment: 8 pages, 4 figure

Long-term flood-hazard modeling for coastal areas using InSAR measurements and a hydrodynamic model: The case study of Lingang New City, Shanghai

In this paper, we study long-term coastal flood risk of Lingang New City, Shanghai, considering 100- and 1000-year coastal flood return periods, local seal-level rise projections, and long-term ground subsidence projections. TanDEM-X satellite data acquired in 2012 were used to generate a high-resolution topography map, and multi-sensor InSAR displacement time-series were used to obtain ground deformation rates between 2007 and 2017. Both data sets were then used to project ground deformation rates for the 2030s and 2050s. A 2-D flood inundation model (FloodMap-Inertial) was employed to predict coastal flood inundation for both scenarios. The results suggest that the sea-level rise, along with land subsidence, could result in minor but non-linear impacts on coastal inundation over time. The flood risk will primarily be determined by future exposure and vulnerability of population and property in the floodplain. Although the flood risk estimates show some uncertainties, particularly for long-term predictions, the methodology presented here could be applied to other coastal areas where sea level rise and land subsidence are evolving in the context of climate change and urbanization

Antibiotic activity altered by competitive interactions between two coral reef – associated bacteria

Microbes produce natural products that mediate interactions with each other and with their environments, representing a potential source of antibiotics for human use. The biosynthesis of some antibiotics whose constitutive production otherwise remains low has been shown to be induced by competing microbes. Competition among macroorganism hosts may further influence the metabolic outputs of members of their microbiomes, especially near host surfaces where hosts and microbial symbionts come into close contact. At multiple field sites in Fiji, we collected matched samples of corals and algae that were freestanding or in physical contact with each other, cultivated bacteria from their surfaces, and explored growth-inhibitory activities of these bacteria against marine and human pathogens. In the course of the investigation, an interaction was discovered between two coral-associated actinomycetes in which an Agrococcus sp. interfered with the antibiotic output of a Streptomyces sp. Several diketopiperazines identified from the antibiotic-producing bacterium could not, on their own, account for the antibiotic activity indicating that other, as yet unidentified molecule(s) or molecular blends, possibly including diketopiperazines, are likely involved. This observation highlights the complex molecular dynamics at play among microbiome constituents. The mechanisms through which microbial interactions impact the biological activities of specialized metabolites deserve further attention considering the ecological and commercial importance of bacterial natural products

High content live cell imaging for the discovery of new antimalarial marine natural products

<p>Abstract</p> <p>Background</p> <p>The human malaria parasite remains a burden in developing nations. It is responsible for up to one million deaths a year, a number that could rise due to increasing multi-drug resistance to all antimalarial drugs currently available. Therefore, there is an urgent need for the discovery of new drug therapies. Recently, our laboratory developed a simple one-step fluorescence-based live cell-imaging assay to integrate the complex biology of the human malaria parasite into drug discovery. Here we used our newly developed live cell-imaging platform to discover novel marine natural products and their cellular phenotypic effects against the most lethal malaria parasite, <it>Plasmodium falciparum</it>.</p> <p>Methods</p> <p>A high content live cell imaging platform was used to screen marine extracts effects on malaria. Parasites were grown <it>in vitro </it>in the presence of extracts, stained with RNA sensitive dye, and imaged at timed intervals with the BD Pathway HT automated confocal microscope.</p> <p>Results</p> <p>Image analysis validated our new methodology at a larger scale level and revealed potential antimalarial activity of selected extracts with a minimal cytotoxic effect on host red blood cells. To further validate our assay, we investigated parasite's phenotypes when incubated with the purified bioactive natural product bromophycolide A. We show that bromophycolide A has a strong and specific morphological effect on parasites, similar to the ones observed from the initial extracts.</p> <p>Conclusion</p> <p>Collectively, our results show that high-content live cell-imaging (HCLCI) can be used to screen chemical libraries and identify parasite specific inhibitors with limited host cytotoxic effects. All together we provide new leads for the discovery of novel antimalarials.</p

Antibacterial Oligomeric Polyphenols from the Green Alga Cladophora socialis

A series of oligomeric phenols including the known natural product 3,4,3′,4′-tetrahydroxy-1,1′-biphenyl (3), the previously synthesized 2,3,8,9-tetrahydroxybenzo[c]-chromen-6-one (4), and eight new related natural products, cladophorols B−I (5−12), were isolated from the Fijian green alga Cladophora socialis and identified by a combination of NMR spectroscopy, mass spectrometric analysis, and computational modeling using DFT calculations. J-resolved spectroscopy and line width reduction by picric acid addition aided in resolving the heavily overlapped aromatic signals. A panel of Gram-positive and Gram-negative pathogens used to evaluate pharmacological potential led to the determination that cladophorol C (6) exhibits potent antibiotic activity selective toward methicillin-resistant Staphylococcus aureus (MRSA) with an MIC of 1.4 μg/mL. Cladophorols B (5) and D−H (7−11) had more modest but also selective antibiotic potency. Activities of cladophorols A−I (4−12) were also assessed against the asexual blood stages of Plasmodium falciparum and revealed cladophorols A (4) and B (5) to have modest activity with EC50 values of 0.7 and 1.9 μg/mL, respectively

Biochemical warfare on the reef : the role of glutathione transferases in consumer tolerance of dietary prostaglandins

© 2010 The Authors. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS ONE 5 (2010): e8537, doi:10.1371/journal.pone.0008537.Despite the profound variation among marine consumers in tolerance for allelochemically-rich foods, few studies have examined the biochemical adaptations underlying diet choice. Here we examine the role of glutathione S-transferases (GSTs) in the detoxification of dietary allelochemicals in the digestive gland of the predatory gastropod Cyphoma gibbosum, a generalist consumer of gorgonian corals. Controlled laboratory feeding experiments were used to investigate the influence of gorgonian diet on Cyphoma GST activity and isoform expression. Gorgonian extracts and semi-purified fractions were also screened to identify inhibitors and possible substrates of Cyphoma GSTs. In addition, we investigated the inhibitory properties of prostaglandins (PGs) structurally similar to antipredatory PGs found in high concentrations in the Caribbean gorgonian Plexaura homomalla. Cyphoma GST subunit composition was invariant and activity was constitutively high regardless of gorgonian diet. Bioassay-guided fractionation of gorgonian extracts revealed that moderately hydrophobic fractions from all eight gorgonian species examined contained putative GST substrates/inhibitors. LC-MS and NMR spectral analysis of the most inhibitory fraction from P. homomalla subsequently identified prostaglandin A2 (PGA2) as the dominant component. A similar screening of commercially available prostaglandins in series A, E, and F revealed that those prostaglandins most abundant in gorgonian tissues (e.g., PGA2) were also the most potent inhibitors. In vivo estimates of PGA2 concentration in digestive gland tissues calculated from snail grazing rates revealed that Cyphoma GSTs would be saturated with respect to PGA2 and operating at or near physiological capacity. The high, constitutive activity of Cyphoma GSTs is likely necessitated by the ubiquitous presence of GST substrates and/or inhibitors in this consumer's gorgonian diet. This generalist's GSTs may operate as ‘all-purpose’ detoxification enzymes, capable of conjugating or sequestering a broad range of lipophilic gorgonian compounds, thereby allowing this predator to exploit a range of chemically-defended prey, resulting in a competitive dietary advantage for this species.Financial support for this work was provided by the Ocean Life Institute Tropical Research Initiative Grant (WHOI) to KEW and MEH; the Robert H. Cole Endowed Ocean Ventures Fund (WHOI) to KEW; the National Undersea Research Center - Program Development Proposal (CMRC-03PRMN0103A) to KEW; Walter A. and Hope Noyes Smith, and a National Science Foundation Graduate Research Fellowship to KEW