Microbiotic soil crusts in the Sahel of Western Niger and their influence on Soil POROSITY and water dynamics

International audienceMicrobiotic soil crusts are common features of the surface of fallow land in Western Niger. We investigated the interaction between these microbial covers and the porosity and water dynamics of soils at the surface of a Sahelian landscape. The soil pore system was examined by microscopic observations and mercury porosimetry. The soil water retention capacity was measured using a Richard pressure membrane apparatus. Runoff measurements were performed in situ at a one m2 scale under natural rainfall. Samples with dense cyanobacterial cover had microbially-originated pores ranging from 0.04 and 50 μm in size. These samples also showed higher total soil porosity and retained two to four times more water than samples with thin microbial cover. These properties are closely related to the hydrophobic nature of cyanobacterial components. Final runoff values obtained on densely covered surfaces were significantly higher compared to those measured on surfaces with thin microbial cover due to the geometry of the microbially-originated pore system and its functioning

Room-temperature exciton-polaritons with two-dimensional WS2

Two-dimensional transition metal dichalcogenides exhibit strong optical transitions with significant potential for optoelectronic devices. In particular they are suited for cavity quantum electrodynamics in which strong coupling leads to polariton formation as a root to realisation of inversionless lasing, polariton condensationand superfluidity. Demonstrations of such strongly correlated phenomena to date have often relied on cryogenic temperatures, high excitation densities and were frequently impaired by strong material disorder. At room-temperature, experiments approaching the strong coupling regime with transition metal dichalcogenides have been reported, but well resolved exciton-polaritons have yet to be achieved. Here we report a study of monolayer WS$_2$ coupled to an open Fabry-Perot cavity at room-temperature, in which polariton eigenstates are unambiguously displayed. In-situ tunability of the cavity length results in a maximal Rabi splitting of $\hbar \Omega_{\rm{Rabi}} = 70$ meV, exceeding the exciton linewidth. Our data are well described by a transfer matrix model appropriate for the large linewidth regime. This work provides a platform towards observing strongly correlated polariton phenomena in compact photonic devices for ambient temperature applications.Comment: 12 pages, 6 figure

Superparamagnetic Liposomes for MRI Monitoring and External Magnetic Field-Induced Selective Targeting of Malignant Brain Tumors

Magnetic-fluid-loadedliposomes (MFLs) of optimized magnetic responsiveness are newly worked out from the entrapment of superparamagnetic maghemite nanocrystals in submicronic PEG-ylated rhodamine-labelled phospholipid vesicles. This nanoplatform provides an efficient tool for the selective magnetic targeting of malignant tumors localized in brain and non-invasive traceability by MRI through intravascular administration. As assessed by in vivo 7-T MRI and ex vivo electron spin resonance, 4-h exposure to 190-T m–1magnetic field gradient efficiently concentrates MFLs into human U87 glioblastoma implanted in the striatum of mice. The magnetoliposomes are then longer retained therein as checked by MRI monitoring over a 24-h period. Histological analysis by confocal fluorescence microscopy confirms the significantly boosted accumulation of MFLs in the malignant tissue up to the intracellular level. Electron transmission microscopy reveals effective internalization by endothelial and glioblastoma cells of the magnetically conveyed MFLs as preserved vesicle structures. The magnetic field gradient emphasizes MFL distribution solely in the tumors according to the enhanced permeability and retention (EPR) effect while comparatively very low amounts are recovered in the other cerebral areas. Such a selective targeting precisely traceable by MRI is promising for therapeutic applications since the healthy brain tissue can be expected to be spared during treatments by deleterious anticancer drugs carried by magnetically guided MFLs

Eine „dienende Rolle“ für den Finanzsektor? Nicht dienen, sondern funktionieren!

The image is undisputed in the political debate that the function of the financial sector is to "play servant" to the real economy, but the consequences derived from this debate are controversial. Clearer is the academic concept to restrict the functions of the financial sector deliberately. But such restriction is hardly convincing from the different persepectives of functionality. Because of this indetermination and, respectively, restriction, a "servant role" is apparently inappropriate as a useful yardstick for reorienting the financial sector. In line with this image, it would certainly be possible to improve crisis prevention, but at the price of cuts in important functions so that a "sevant role" as a concept of crisis prevention would not be desirable either

Robust, tunable, and high purity triggered single photon source at room temperature using a nitrogen-vacancy defect in diamond in an open microcavity

We report progress in the development of tunable room temperature triggered single photon sources based on single nitrogen-vacancy (NV) centres in nanodiamond coupled to open access optical micro-cavities. The feeding of fluorescence from an NV centre into the cavity mode increases the spectral density of the emission and results in an output stream of triggered single photons with spectral line width of order 1 nm, tunable in the range 640 - 700 nm. We record single photon purities exceeding 96% and estimated device efficiencies up to 3%. We compare performance using plano-concave microcavities with radii of curvature from 25 mu m to 4 mu m and show that up to 17% of the total emission is fed into the TEM00 mode. Pulsed Hanbury-Brown Twiss (HBT) interferometry shows that an improvement in single photon purity is facilitated due to the increased spectral density. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License

The transmission of unconventional monetary policy to bank credit supply : evidence from the TLTRO

We assess the transmission of the Targeted Longer-Term Refinancing Operations (TLTRO) to the bank credit supply for the Euro area (2014:05-2018:01) and for Portugal (2011:01-2018:01), using a panel data setup. For the Euro area, we find a positive relationship between the TLTRO and the amount of credit granted to the real economy. For the vulnerable countries, the effects of the TLTRO on the stock of credit increased from 2016 to 2017. Among the group of small banks, the effects are stronger in less vulnerable countries. We also find that competition has no statistically significant impact on the transmission of the TLTRO to the bank credit supply for the Euro area. For Portugal, using a difference-in-differences model, we find no statistically significant impact of the TLTRO on credit granted by banks. Finally, bidding banks set lower interest rates than non-bidding banks and the difference seems to be larger in 2017. In Portugal, the effects of the TLTRO on loan interest rates also increased from 2016 to 2017 and are stronger for small banks.info:eu-repo/semantics/publishedVersio

Organomineralization

Encyclopedia of Geobiolog