Risk Assessment Method for Back-Reflections from Space Debris in High-Power Laser Ranging

A versatile method to assess the risk arising from pulsed laser radiation reflected from space debris is presented which is based on the thresholds of maximum permissible exposure (MPE) to laser irradiation as they apply by European legislation. Gaussian beam propagation is employed considering atmospheric attenuation and turbulence-induced beam broadening. For the reflected beam specular reflection is considered as a worst-case estimate, comprising effects of target outshining and diffraction. System-specific risk charts are derived to assess the amount by which the MPE value might be exceeded for downlink reflections. These charts are directly connected to the orbital and rotational motion of the debris object via the resulting glint motion and size which is determined by the overpass geometr

A supramolecular assembly formed by influenza A virus genomic RNA segments

The influenza A virus genome consists of eight viral RNAs (vRNAs) that form viral ribonucleoproteins (vRNPs). Even though evidence supporting segment-specific packaging of vRNAs is accumulating, the mechanism ensuring selective packaging of one copy of each vRNA into the viral particles remains largely unknown. We used electron tomography to show that the eight vRNPs emerge from a common ‘transition zone’ located underneath the matrix layer at the budding tip of the virions, where they appear to be interconnected and often form a star-like structure. This zone appears as a platform in 3D surface rendering and is thick enough to contain all known packaging signals. In vitro, all vRNA segments are involved in a single network of intermolecular interactions. The regions involved in the strongest interactions were identified and correspond to known packaging signals. A limited set of nucleotides in the 5′ region of vRNA 7 was shown to interact with vRNA 6 and to be crucial for packaging of the former vRNA. Collectively, our findings support a model in which the eight genomic RNA segments are selected and packaged as an organized supramolecular complex held together by direct base pairing of the packaging signals

Hematopoietic Cell Transplantation Outcomes in Monosomal Karyotype Myeloid Malignancies

The presence of monosomal karyotype (MK+) in acute myeloid leukemia (AML) is associated with dismal outcomes. We evaluated the impact of MK+ in AML (MK+AML, N=240) and in myelodysplastic syndrome (MK+MDS, N=221) on hematopoietic cell transplantation (HCT) outcomes compared to other cytogenetically defined groups (AML, N=3,360; MDS, N=1,373) as reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) from 1998 to 2011. MK+AML was associated with higher disease relapse (hazard ratio [HR] 1.98, p<0.01), similar transplant related mortality (TRM, HR 1.01, p=0.9) and worse survival (HR 1.67, p<0.01) compared to other cytogenetically defined AML. Among patients with MDS, MK+MDS was associated with higher disease relapse (HR 2.39, p<0.01), higher TRM (HR 1.80, p<0.01) and worse survival (HR 2.02, p<0.01). Subset analyses comparing chromosome 7 abnormalities (del7/7q) with or without MK+ demonstrated higher mortality for MK+ disease in for both AML (HR 1.72, p<0.01) and MDS (HR1.79, p<0.01). The strong negative impact of MK+ in myeloid malignancies was observed in all age groups and using either myeloablative or reduced intensity conditioning regimens. Alternative approaches to mitigate disease relapse in this population are needed

Towards long-term standardised carbon and greenhouse gas observations for monitoring Europe's terrestrial ecosystems : a review

Research infrastructures play a key role in launching a new generation of integrated long-term, geographically distributed observation programmes designed to monitor climate change, better understand its impacts on global ecosystems, and evaluate possible mitigation and adaptation strategies. The pan-European Integrated Carbon Observation System combines carbon and greenhouse gas (GHG; CO2, CH4, N2O, H2O) observations within the atmosphere, terrestrial ecosystems and oceans. High-precision measurements are obtained using standardised methodologies, are centrally processed and openly available in a traceable and verifiable fashion in combination with detailed metadata. The Integrated Carbon Observation System ecosystem station network aims to sample climate and land-cover variability across Europe. In addition to GHG flux measurements, a large set of complementary data (including management practices, vegetation and soil characteristics) is collected to support the interpretation, spatial upscaling and modelling of observed ecosystem carbon and GHG dynamics. The applied sampling design was developed and formulated in protocols by the scientific community, representing a trade-off between an ideal dataset and practical feasibility. The use of open-access, high-quality and multi-level data products by different user communities is crucial for the Integrated Carbon Observation System in order to achieve its scientific potential and societal value.Peer reviewe

Directional trends in species composition over time can lead to a widespread overemphasis of year‐to‐year asynchrony

Questions: Compensatory dynamics are described as one of the main mechanisms that increase community stability, e.g., where decreases of some species on a year‐to‐year basis are offset by an increase in others. Deviations from perfect synchrony between species (asynchrony) have therefore been advocated as an important mechanism underlying biodiversity effects on stability. However, it is unclear to what extent existing measures of synchrony actually capture the signal of year‐to‐year species fluctuations in the presence of long‐term directional trends in both species abundance and composition (species directional trends hereafter). Such directional trends may lead to a misinterpretation of indices commonly used to reflect year‐to‐year synchrony. Methods: An approach based on three‐term local quadrat variance (T3) which assesses population variability in a three‐year moving window, was used to overcome species directional trend effects. This “detrending” approach was applied to common indices of synchrony across a worldwide collection of 77 temporal plant community datasets comprising almost 7,800 individual plots sampled for at least six years. Plots included were either maintained under constant “control” conditions over time or were subjected to different management or disturbance treatments. Results: Accounting for directional trends increased the detection of year‐to‐year synchronous patterns in all synchrony indices considered. Specifically, synchrony values increased significantly in ~40% of the datasets with the T3 detrending approach while in ~10% synchrony decreased. For the 38 studies with both control and manipulated conditions, the increase in synchrony values was stronger for longer time series, particularly following experimental manipulation. Conclusions: Species’ long‐term directional trends can affect synchrony and stability measures potentially masking the ecological mechanism causing year‐to‐year fluctuations. As such, previous studies on community stability might have overemphasised the role of compensatory dynamics in real‐world ecosystems, and particularly in manipulative conditions, when not considering the possible overriding effects of long‐term directional trends

LOTVS: a global collection of permanent vegetation plots

Analysing temporal patterns in plant communities is extremely important to quantify the extent and the consequences of ecological changes, especially considering the current biodiversity crisis. Long-term data collected through the regular sampling of permanent plots represent the most accurate resource to study ecological succession, analyse the stability of a community over time and understand the mechanisms driving vegetation change. We hereby present the LOng-Term Vegetation Sampling (LOTVS) initiative, a global collection of vegetation time-series derived from the regular monitoring of plant species in permanent plots. With 79 data sets from five continents and 7,789 vegetation time-series monitored for at least 6 years and mostly on an annual basis, LOTVS possibly represents the largest collection of temporally fine-grained vegetation time-series derived from permanent plots and made accessible to the research community. As such, it has an outstanding potential to support innovative research in the fields of vegetation science, plant ecology and temporal ecology

Climate control of terrestrial carbon exchange across biomes and continents

Peer reviewe

Combined molecular and metallic particulate laser-induced contamination testing: de-risking activity for the LISA space mission

To mitigate risks due to laser-induced contamination (LIC) for the LISA space mission, we have carried out an extensive LIC test campaign, including a series of short duration tests with different test parameters, as well as a long-duration test. Those previous experimental results as well as theoretical considerations indicate that LIC might be less of a concern for the LISA mission. A remaining concern is whether LIC could occur in the presence of metallic particles on optical surfaces and whether a higher pressure does have an impact. Our ongoing research thus aims at testing for a possible deposit formation in a combined LIC and metallic particulate contamination test. Therefore, a HR optics is contaminated with metallic (aluminum) particles, mounted in the sample holder and tested within a similar test setup used for previous tests. The test is performed at a pressure similar to the actual expected pressure of 10-5 mbar at the optical bench during the mission (previous tests at 10-8 mbar). These tests do not indicate that LIC is a concern and metallic particulate contaminants seem not to accelerate or trigger LIC in this laser regime

Effects of high-power laser radiation on polymers for 3D printing micro-optics

3D printing has become a widely used technique for manufacturing micro-optical components for sensing, measurements, biomedical and quantum technologies. Hence, knowing the maximum usable power or damage thresholds of 3D-printed micro-optics becomes crucial. Here we present a first study of the damage threshold values of the IP-S photoresist under high-power cw-, fs-, and ns-pulsed laser radiation with wavelengths in the NIR range. We also study the differences between visual evaluation using bright-field microscopy, DIC-microscopy, and beam-profile damage detection. Finally, we present several application-inspired use cases of 3D printed fiber micro-optics, reaching 10.5 W output power of cw-radiation at 915 nm and 4.5 W and 550 fs pulsed operation at 1040 nm