Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

SPHERE, the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument for the VLT is optimized towards reaching the highest contrast in a limited field of view and at short distances from the central star, thanks to an extreme AO system. SPHERE is very well suited to study the close environment of Betelgeuse, and has a strong potential for detecting the ejection activity around this key red supergiant.

The objective of the present study was to compare the performance of seven different, widely applied crop models in predicting heat and drought stress effects. The study was part of a recent suite of model inter-comparisons initiated at European level and constitutes a component that has been lacking in the analysis of sources of uncertainties in crop models used to study the impacts of climate change. There was a specific focus on the sensitivity of models for winter wheat and maize to extreme weather conditions (heat and drought) during the short but critical period of 2 weeks after the start of flowering. Two locations in Austria, representing different agro-climatic zones and soil conditions, were included in the simulations over 2 years, 2003 and 2004, exhibiting contrasting weather conditions. In addition, soil management was modified at both sites by following either ploughing or minimum tillage. Since no comprehensive field experimental data sets were available, a relative comparison of simulated grain yields and soil moisture contents under defined weather scenarios with modified temperatures and precipitation was performed for a 2-week period after flowering. The results may help to reduce the uncertainty of simulated crop yields to extreme weather conditions through better understanding of the models’ behaviour. Although the crop models considered (DSSAT, EPIC, WOFOST, AQUACROP, FASSET, HERMES and CROPSYST) mostly showed similar trends in simulated grain yields for the different weather scenarios, it was obvious that heat and drought stress caused by changes in temperature and/or precipitation for a short period of 2 weeks resulted in different grain yields simulated by different models. The present study also revealed that the models responded differently to changes in soil tillage practices, which affected soil water storage capacity.

The present work shows results on elemental distribution analyses in Cu(In,Ga)Se2 thin films for solar cells performed by use of wavelength-dispersive and energy-dispersive X-ray spectrometry (EDX) in a scanning electron microscope, EDX in a transmission electron microscope, X-ray photoelectron, angle-dependent soft X-ray emission, secondary ion-mass (SIMS), time-of-flight SIMS, sputtered neutral mass, glow-discharge optical emission and glow-discharge mass, Auger electron, and Rutherford backscattering spectrometry, by use of scanning Auger electron microscopy, Raman depth profiling, and Raman mapping, as well as by use of elastic recoil detection analysis, grazing-incidence X-ray and electron backscatter diffraction, and grazing-incidence X-ray fluorescence analysis. The Cu(In,Ga)Se2 thin films used for the present comparison were produced during the same identical deposition run and exhibit thicknesses of about 2 μm. The analysis techniques were compared with respect to their spatial and depth resolutions, measuring speeds, availabilities, and detection limits.

The concentration and temperature dependence of the self-diffusion of benzene adsorbed in the metal-organic framework MOF-5 (IRMOF-1) is studied by pulsed field gradient (PFG) NMR spectroscopy. When increasing the loading from 10 to 20 molecules per unit cell of MOF-5, the experimental diffusion data drop by a factor of about 3 while current molecular dynamic (MD) simulations predict slightly increasing diffusion coefficients for this range of loadings. The observation is rationalized using the recently predicted clustering of adsorbate molecules in microporous systems for temperatures well below the adsorbate critical temperature. Necessary improvements of molecular simulation models for predicting diffusivities under such conditions are discussed.

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

We report on a measles outbreak originating in an anthroposophic community in Austria, 2008. A total of 394 (94·9%) cases fulfilled the outbreak case definition including 168 cases affiliated to the anthroposophic community. The source case was a school pupil from Switzerland. The Austrian outbreak strain was genotype D5, indistinguishable from the Swiss outbreak strain. A school-based retrospective cohort study in the anthroposophic school demonstrated a vaccine effectiveness of 97·3% in pupils who had received a single dose of measles-containing vaccine and 100% in those who had received two doses. The vaccination coverage of the cases in the anthroposophic community was 0·6%. Of the 226 outbreak cases not belonging to the anthroposophic community, the 10–24 years age group was the most affected. Our findings underline the epidemiological significance of suboptimal vaccination coverage in anthroposophic communities and in older age groups of the general population in facilitating measles virus circulation. The findings of this outbreak investigation suggest that the WHO European Region is unlikely to achieve its 2010 target for measles and rubella elimination.

The ability of electron microscopes to analyze all the atoms in individual nanostructures is limited by lens aberrations. However, recent advances in aberration-correcting electron optics have led to greatly enhanced instrument performance and new techniques of electron microscopy. The development of an ultrastable electron microscope with aberration-correcting optics and a monochromated high-brightness source has significantly improved instrument resolution and contrast. In the present work, we report information transfer beyond 50 pm and show images of single gold atoms with a signal-to-noise ratio as large as 10. The instrument's new capabilities were exploited to detect a buried Σ3 {112} grain boundary and observe the dynamic arrangements of single atoms and atom pairs with sub-angstrom resolution. These results mark an important step toward meeting the challenge of determining the three-dimensional atomic-scale structure of nanomaterials.

Extended abstract of a paper presented at MC 2007, 33rd DGE Conference in Saarbrücken, Germany, September 2 – September 7, 2007

The extreme contrast in mass and luminosity between the extra-solar planets and their host stars make detailed studies of these planets very challenging. In particular, direct observations of extra-solar planets is still beyond the capabilities of the currently available instrumentation, save for perhaps a few extreme cases of very young and massive planets at large distances from the central star. While progress in instrumentation might allow significant progress in detection capabilities either with the 8 and 10-m ground-based telescopes (Planet Finder instruments on the VLT and Gemini) or with the next generation space telescope (JWST), imaging of extra-solar planets over a wide range of parameters, and possibly down to terrestrial planets, will require extremely large ground-based telescopes like OWL or dedicated space instrumentation (TPF or Darwin for instance). We outline here the scientific objectives of EPICS, the OWL Earth-like Planet Imager and Spectrograph, summarize the corresponding high level requirements, present the foreseen observing modes and give a first estimate of its performance.

The European southern observatory ESO is currently undertaking the ambitious task of building a “Planet Finder” instrument for the VLT. The concept for this instrument includes a 3D spectroscopic imager assisted by a very powerful eXtreme AO system. In one of the two phase-A studies for this project, we have developed a simulation software for this kind of instrument which has now been extended and applied to the case of various ELTs. In this presentation, we give results of simulations and discuss achievable signal to noise ratios and prospects for detection and characterization from young gas giants down to terrestrial type planets. ELTs of various diameters are considered as well as a set of environmental conditions.

Direct detection and spectral characterization of extrasolar planets is one of the most exciting but also one of the most challenging area in modern astronomy. For its second generation instrumentation on the VLT, ESO has supported two phase A studies for a so-called “Planet Finder” dedicated instrument. Based on the results of these two studies, a unique instrument is now considered for first light in early 2010, including a powerful extreme adaptive optics system, various coronagraphs, an infrared differential imaging camera, an infrared integral field spectrograph and a visible differential polarimeter. We will briefly summarize the science objectives and requirements, describe the proposed conceptual design and discuss the main limitations and corresponding instrumental issues of such a system. We will also derive the expected performance of the proposed Planet Finder and present the project organization.

This paper presents the scientific case for a next generation adaptive optics instrument at the VLT, temporarily named “Planet Finder”, that is aimed at detecting and characterizing extrasolar planets through the direct analysis of their emitted photons in the visible and at near-IR wavelengths. We discuss the observational niche of such an instrument to have first light in 2010, in complement to other planet search methods. To improve the efficiency (and consistency) of the search for planets with the PF, the observations will need to be organized in the form of an extensive survey of hundreds of nearby stars, predicted outputs of which are also described here. This summarizes the study phase of the instrument, conducted by two competitive teams and the recent merging of both studies, regarding the scientific impact of Planet Finder.

Light reflected from planets is polarized. This basic property of planets provides the possibility for detecting and characterizing extra-solar planets using polarimetry. The expected polarization properties of extra-solar planets are discussed that can be inferred from polarimetry of “our” solar system planets. They show a large variety of characteristics depending on the atmospheric and/or surface properties. Best candidates for a polarimetric detection are extra-solar planets with an optically thick Rayleigh scattering layer.

Even the detection of highly polarized extra-solar planets requires a very sophisticated instrument. We present the results from a phase A (feasibility) study for a polarimetric arm in the ESO VLT planet finder instrument. It is shown that giant planets around nearby stars can be searched and investigated with an imaging polarimeter, combined with a powerful AO system and a coronagraph at an 8 m class telescope.

A similar type of polarimeter is also considered for the direct detection of terrestrial planets using an AO system on one of the future Extremely Large Telescopes.