Transverse nuclear spin relaxation measurements employing Carr-Purcell (CP) pulse sequences have been used to determine the viscoelastic properties of quasi-spherical membrane vesicles with controlled radii R 0 . The observed relaxation rates, R 2 CP (ω), exhibit a linear dependence on the inverse pulse frequency over a wide frequency range in the kHz regime and then level off to a constant "plateau" value independent of ω. Within the linear dispersion regime, the same relaxation rates are detected for unilamellar and oligolamellar vesicles, indicating that the interbilayer coupling is weak and has no effect on the measured relaxation curves. Analysis of the experimental dispersion profiles is performed using a slow-motional model in which two different relaxation processes are considered (i.e., vesicle shape fluctuations and molecular translational diffusion). It is shown that for vesicle radii R 0 g 200 nm lateral diffusion across the vesicle shell is too slow to contribute significantly to transverse spin relaxation in the kHz range. Rather, vesicle shape fluctuations constitute the dominant transverse relaxation process. Model calculations reveal that R 2 CP (ω), induced by vesicle fluctuations, depends linearly on ω -1 over a wide frequency range in the kHz regime. Notably, within this linear dispersion regime, the bending elastic modulus κ is the only relevant parameter because the magnitude of R 2 CP (ω) does not depend on R 0 , the effective lateral tension σ, and the viscosity of the surrounding fluid η. On the other hand, R 0 , σ, η, and κ determine the frequency at which R 2 CP (ω) levels off to a constant plateau value. Thus, analysis of the linear dispersion regime is a direct way to determine the bending rigidity κ. For the studied DMPC and DMPC/cholesterol vesicles, the κ values vary from (1.5 ( 0.1) × 10 -20 J to (8.3 ( 0.1) × 10 -20 J. From the plateau in the experimental dispersion profiles, values for the effective lateral tension of σ ) 3 ( 1 and 4 ( 1 have been extracted. It appears that transverse NMR relaxation involving CP sequences represents a powerful tool for the study of the viscoelastic properties of membrane vesicles.

Covid-19 affects the personal lives of millions and led to an economic crisis. Changed behavioral patterns and a reduction of industrial activity result in a reduction in power demand, and thus Covid-19 impacts the power systems around the world. Bottom-up mapping of the effect of Covid-19 on the energy demand is challenging, if not impossible. In order to analyze the impact of the pandemic on power demand, we instead propose a simplified approach based on an econometric analysis that quantifies the country-wide load reduction of Covid-19, using the number of active cases as well as the specific lockdown period as proxies. The time span covered is from 1 January 2016 to 31 August 2020. This long time span allows us to investigate the effect of Covid-19 on the power demand. We find that in Germany (DE) and Great Britain (GB) the power demand is reduced by about 1–1.7 MW per case, while in France the demand increased by 1 MW per case during times outside of the lockdown. On the other hand, in France the lockdown itself has a much higher load reduction effect in France than in GB and DE. Based on the elasticity of power demand regarding Covid-19 cases, we calculate the impact of Covid-19 on the power prices through reduced loads. We find that Covid-19 reduced power prices by 3 to 6 EUR per MWh. The effect of Covid-19 on carbon emissions in the power sector is likely to be small. In Germany, the country with the highest absolute level, emissions in the power sector were reduced by approximately 2% (4 Mio. t CO2).

No abstract

No abstract

Climate change and biodiversity loss trigger policies targeting and impacting local communities worldwide. However, research and policy implementation often fail to sufficiently consider community responses and involve them. We present the results of a collective self-assessment exercise for eight case studies of communications regarding climate change or biodiversity loss between project teams and local communities. We develop eight indicators of good stakeholder communication, reflecting the scope of Verran (2002)'s concept of postcolonial moments as a communicative utopia. We demonstrate that applying our indicators can enhance communication and enable community responses. However, we discover a divergence between timing, complexity, and (introspective) effort. Three cases qualify for postcolonial moments, but scrutinizing power relations and genuine knowledge co-production remain rare. While we verify the potency of various instruments for deconstructing science, their sophistication cannot substitute trust building and epistemic/transdisciplinary awareness. Lastly, we consider that reforming inadequate funding policies helps improving the work in and with local communities.