Angle-resolved cathodoluminescence imaging polarimetry

Cathodoluminescence spectroscopy (CL) allows characterizing light emission in bulk and nanostructured materials and is a key tool in fields ranging from materials science to nanophotonics. Previously, CL measurements focused on the spectral content and angular distribution of emission, while the polarization was not fully determined. Here we demonstrate a technique to access the full polarization state of the cathodoluminescence emission, that is the Stokes parameters as a function of the emission angle. Using this technique, we measure the emission of metallic bullseye nanostructures and show that the handedness of the structure as well as nanoscale changes in excitation position induce large changes in polarization ellipticity and helicity. Furthermore, by exploiting the ability of polarimetry to distinguish polarized from unpolarized light, we quantify the contributions of different types of coherent and incoherent radiation to the emission of a gold surface, silicon and gallium arsenide bulk semiconductors. This technique paves the way for in-depth analysis of the emission mechanisms of nanostructured devices as well as macroscopic media.Comment: 8 figures. Includes supplementary informatio

Increased insolation threshold for runaway greenhouse processes on Earth like planets

Because the solar luminosity increases over geological timescales, Earth climate is expected to warm, increasing water evaporation which, in turn, enhances the atmospheric greenhouse effect. Above a certain critical insolation, this destabilizing greenhouse feedback can "runaway" until all the oceans are evaporated. Through increases in stratospheric humidity, warming may also cause oceans to escape to space before the runaway greenhouse occurs. The critical insolation thresholds for these processes, however, remain uncertain because they have so far been evaluated with unidimensional models that cannot account for the dynamical and cloud feedback effects that are key stabilizing features of Earth's climate. Here we use a 3D global climate model to show that the threshold for the runaway greenhouse is about 375 W/m$^2$, significantly higher than previously thought. Our model is specifically developed to quantify the climate response of Earth-like planets to increased insolation in hot and extremely moist atmospheres. In contrast with previous studies, we find that clouds have a destabilizing feedback on the long term warming. However, subsident, unsaturated regions created by the Hadley circulation have a stabilizing effect that is strong enough to defer the runaway greenhouse limit to higher insolation than inferred from 1D models. Furthermore, because of wavelength-dependent radiative effects, the stratosphere remains cold and dry enough to hamper atmospheric water escape, even at large fluxes. This has strong implications for Venus early water history and extends the size of the habitable zone around other stars.Comment: Published in Nature. Online publication date: December 12, 2013. Accepted version before journal editing and with Supplementary Informatio

Ethanol exposure increases mutation rate through error-prone polymerases

International audienceEthanol is a ubiquitous environmental stressor that is toxic to all lifeforms. Here, we use the model eukaryote Saccharomyces cerevisiae to show that exposure to sublethal ethanol concentrations causes DNA replication stress and an increased mutation rate. Specifically, we find that ethanol slows down replication and affects localization of Mrc1, a conserved protein that helps stabilize the replisome. In addition, ethanol exposure also results in the recruitment of error-prone DNA polymerases to the replication fork. Interestingly, preventing this recruitment through mutagenesis of the PCNA/Pol30 polymerase clamp or deleting specific error-prone polymerases abolishes the mutagenic effect of ethanol. Taken together, this suggests that the mutagenic effect depends on a complex mechanism, where dysfunctional replication forks lead to recruitment of error-prone polymerases. Apart from providing a general mechanistic framework for the mutagenic effect of ethanol, our findings may also provide a route to better understand and prevent ethanol-associated carcinogenesis in higher eukaryotes

Second generation anticoagulant rodenticide residues in barn owls 2021

The current report is the seventh in a series of annual reports that describe the monitoring of second-generation anticoagulant rodenticide (SGAR) liver residues in barn owls Tyto alba in Britain. This work is an element of an overarching monitoring programme undertaken to track the outcomes of stewardship activities associated with the use of anticoagulant rodenticides. The barn owl is used for exposure monitoring as it is considered a sentinel for species that are generalist predators of small mammals in rural areas. The specific work reported here is the measurement of liver SGAR residues in 100 barn owls that died in 2021 at locations across Britain. The residue data are compared with those from 395 barn owls that died between 2006 and 2012 (hereafter termed baseline years), prior to changes in anticoagulant rodenticide (AR) authorisations and onset of stewardship. As in the baseline years, the compounds detected most frequently in barn owls that died in 2021 were brodifacoum, bromadiolone, and difenacoum. Overall, 79% of the owls had detectable liver residues of one or more SGAR. Numbers of barn owls containing detectable residues of flocoumafen and difethialone. There was no significant difference in the proportion of barn owls with detectable liver residues of flocoumafen between the baseline years and 2021. There was a significantly higher proportion of barn owls with detectable liver residues of difethialone in 2021 compared to baseline years (6% vs 0.3%), but it was lower than in some of the intervening years (2016-2019). The ratio of birds with “low” (100 ng/g wet wt.) concentrations for any single SGAR or for ΣSGARs. There were significantly higher proportion of birds from 2021 with “high” concentrations of brodifacoum and summed SGARs (ƩSGARs) detected in their livers compared to baseline years. Average concentrations of brodifacoum, difenacoum, bromadiolone and ΣSGARs in the cohort of owls with “low” residues (100 ng/g wet wt.). There was no significant difference between barn owls from baseline years and from 2021 in the concentrations of “high” residues for all SGAR residues, including ΣSGARs. In contrast, “low” bromadiolone and difenacoum residues were significantly lower in 2021 than baseline years, while “low” brodifacoum residues were significantly higher in 2021 than baseline years. Overall, there were significant differences in liver SGAR accumulation between barn owls that died in baseline years and in 2021: a potential reduction of bromadiolone and difenacoum and an increase of brodifacoum residues from 2016. However, the lack of significant reductions in sum of SGAR residues in barn owls in 2021 suggests that full implementation of stewardship since 2018 has yet to result in a statistically significant reduction in exposure of barn owls to SGARs

Second generation anticoagulant rodenticide residues in barn owls 2022

The current report is the eighth in a series of annual reports that describe the monitoring of second-generation anticoagulant rodenticide (SGAR) liver residues in barn owls Tyto alba in Britain. This work is an element of an overarching monitoring programme undertaken to track the outcomes of stewardship activities associated with the use of anticoagulant rodenticides. The barn owl is used for exposure monitoring as it is considered a sentinel for species that are generalist predators of small mammals in rural areas. The specific work reported here is the measurement of liver SGAR residues in 88 barn owls that died in 2022 at locations across Britain. The residue data are compared with those from 395 barn owls that died between 2006 and 2012 (hereafter termed baseline years), prior to changes in anticoagulant rodenticide (AR) authorisations and onset of stewardship in 2016. As in the baseline years, the compounds detected most frequently in barn owls that died in 2022 were brodifacoum, bromadiolone, and difenacoum. Overall, 79.5% of the owls had detectable liver residues of one or more SGAR. Numbers of barn owls containing detectable residues of flocoumafen and difethialone. There was no significant difference in the proportion of barn owls with detectable liver residues of flocoumafen between 2022 and the baseline years (3% vs 0%). In contrast, there was a significantly higher proportion of barn owls with detectable liver residues of difethialone in 2022 compared to baseline years (6.8% vs 0.3%), but this proportion was lower than in some of the intervening years (2016-2021). The ratio of birds with “low” (100 ng/g wet wt.) concentrations for any single SGAR or for summed SGARs (ΣSGARs). There was a significantly higher proportion of birds with “high” concentrations of brodifacoum detected in their livers in 2022 than in the baseline years. Average concentrations of brodifacoum, difenacoum, bromadiolone and ΣSGARs in the cohort of owls with “low” residues (100 ng/g wet wt.). There was no significant difference between barn owls from baseline years and from 2022 in the concentrations of “high” residues for all SGAR residues, including ΣSGARs. In contrast, “low” bromadiolone and difenacoum residues were significantly lower in birds from 2022 than in the baseline years, while “low” brodifacoum residues were significantly higher in birds from 2022 than in the baseline years. Overall, there were significant differences in liver SGAR accumulation between barn owls that died in baseline years and in 2022: significant reductions of bromadiolone and difenacoum and an increase in brodifacoum residues from 2016. However, the lack of significant reductions in ΣSGAR residues in barn owls in 2022 suggests that full implementation of stewardship since 2018 has yet to result in a statistically significant reduction in exposure of barn owls to SGARs

Targeted Amplicon Sequencing (TAS): A Scalable Next-Gen Approach to Multilocus, Multitaxa Phylogenetics

Next-gen sequencing technologies have revolutionized data collection in genetic studies and advanced genome biology to novel frontiers. However, to date, next-gen technologies have been used principally for whole genome sequencing and transcriptome sequencing. Yet many questions in population genetics and systematics rely on sequencing specific genes of known function or diversity levels. Here, we describe a targeted amplicon sequencing (TAS) approach capitalizing on next-gen capacity to sequence large numbers of targeted gene regions from a large number of samples. Our TAS approach is easily scalable, simple in execution, neither time-nor labor-intensive, relatively inexpensive, and can be applied to a broad diversity of organisms and/or genes. Our TAS approach includes a bioinformatic application, BarcodeCrucher, to take raw next-gen sequence reads and perform quality control checks and convert the data into FASTA format organized by gene and sample, ready for phylogenetic analyses. We demonstrate our approach by sequencing targeted genes of known phylogenetic utility to estimate a phylogeny for the Pancrustacea. We generated data from 44 taxa using 68 different 10-bp multiplexing identifiers. The overall quality of data produced was robust and was informative for phylogeny estimation. The potential for this method to produce copious amounts of data from a single 454 plate (e.g., 325 taxa for 24 loci) significantly reduces sequencing expenses incurred from traditional Sanger sequencing. We further discuss the advantages and disadvantages of this method, while offering suggestions to enhance the approach

Climate Impacts in Europe - The JRC PESETA II Project

The objective of the JRC PESETA II project is to gain insights into the sectoral and regional patterns of climate change impacts in Europe by the end of this century. The study uses a large set of climate model runs and impact categories (ten impacts: agriculture, energy, river floods, droughts, forest fires, transport infrastructure, coasts, tourism, habitat suitability of forest tree species and human health). The project integrates biophysical direct climate impacts into a macroeconomic economic model, which enables the comparison of the different impacts based on common metrics (household welfare and economic activity). Under the reference simulation the annual total damages would be around €190 billion/year, almost 2% of EU GDP. The geographical distribution of the climate damages is very asymmetric with a clear bias towards the southern European regions. More than half of the overall annual EU damages are estimated to be due to the additional premature mortality (€120 billion). Moving to a 2°C world would reduce annual climate damages by €60 billion, to €120 billion (1.2% of GDP)