Refine
Year of publication
- 2016 (1772) (remove)
Document Type
- Article (1185)
- Postprint (209)
- Doctoral Thesis (197)
- Other (69)
- Review (50)
- Monograph/Edited Volume (17)
- Preprint (16)
- Part of a Book (14)
- Conference Proceeding (6)
- Master's Thesis (4)
Language
- English (1772) (remove)
Is part of the Bibliography
- yes (1772) (remove)
Keywords
- German (11)
- Magellanic Clouds (8)
- aggression (8)
- children (8)
- climate change (8)
- prosody (8)
- sentence processing (8)
- adolescents (7)
- prevalence (7)
- self-paced reading (7)
Institute
- Institut für Biochemie und Biologie (283)
- Institut für Geowissenschaften (283)
- Institut für Physik und Astronomie (254)
- Institut für Chemie (198)
- Mathematisch-Naturwissenschaftliche Fakultät (79)
- Institut für Ernährungswissenschaft (75)
- Institut für Mathematik (71)
- Department Psychologie (62)
- Department Linguistik (53)
- Humanwissenschaftliche Fakultät (40)
We report an experimental method to measure the translational and rotational dynamics of colloidal spheres in three dimensions with confocal microscopy and show that the experimental values reasonably agree with the theoretical values. This method can be extended to study rotational dynamics in concentrated colloidal systems and complex bio-systems.
Electric field manipulated nanopatterns in thin films of metalorganic 3-miktoarm star terpolymers
(2016)
We report the effect of electric field on the morphological transitions and ordering behavior of polyferrocenylethylmethylsilane block (PFEMS)-containing copolymers. By analyzing structures in solvent-annealed films of metalorganic sphere-and cylinder-forming diblock copolymers, as well as of 3-miktoarm polyisoprene-arm-polystyrene-arm-PFEMS (3 mu-ISF) terpolymers, we decouple two types of responses to the electric field: morphological transformations as a result of an increase in the volume fraction of the PFEMS block by oxidation of the ferrocenyl groups, and the orientation of the dielectric interfaces of microdomains parallel to the electric field vector. In the case of 3m-ISF, the former effect dominates at high electric field strengths which results in an unexpected cylinder-to-sphere transition, leading to a well-ordered hexagonal dot pattern. Our results demonstrate multiple tunability of ordered microdomain morphologies, suggesting future applications in nanofabrication and surface patterning.
We introduce azobenzene-functionalized polyelectrolyte multilayers as efficient, inexpensive optoacoustic transducers for hyper-sound strain waves in the GHz range. By picosecond transient reflectivity measurements we study the creation of nanoscale strain waves, their reflection from interfaces, damping by scattering from nanoparticles and propagation in soft and hard adjacent materials like polymer layers, quartz and mica. The amplitude of the generated strain epsilon similar to 5 x 10(-4) is calibrated by ultrafast X-ray diffraction.
Purpose - The purpose of this paper is to provide evidence regarding the selection procedures for and characteristics of senior officials in supreme audit institutions (SIAs). Design/methodology/approach - This study follows a quantitative approach using original data collected for presidential elections of SIAs in the 16 federal states in Germany. A fractional logit model is calculated to test different theoretical assumptions in relation to structural, political and individual factors. Findings - The descriptive results confirm the findings of prior research that presidential candidates are elected with very high approval rates. The main determinants are the vote share of the ruling coalition and the executive experience of the presidential candidate. Research limitations/implications - This study focuses on 16 federal states in Germany, but an international comparative perspective covering subnational levels would further augment analysis through the variance of selection procedures and electoral outcomes. Social implications - Independence of auditors is a fundamental issue for the control of the executive, but it seems that there are inevitable trade-offs therein, such as between knowledge of the auditing objects or the politicization of the election process and the independence of the auditor. Originality/value - This study provides novel empirical insights into the election and selection procedures for senior SIA officials at the subnational level, and shows that the executive exerts strong, but functionally reasonable, influence on candidate selection.
Climate change increases riverine carbon outgassing, while export to the ocean remains uncertain
(2016)
Any regular interaction of land and river during flooding affects carbon pools within the terrestrial system, riverine carbon and carbon exported from the system. In the Amazon basin carbon fluxes are considerably influenced by annual flooding, during which terrigenous organic material is imported to the river. The Amazon basin therefore represents an excellent example of a tightly coupled terrestrial-riverine system. The processes of generation, conversion and transport of organic carbon in such a coupled terrigenous-riverine system strongly interact and are climate-sensitive, yet their functioning is rarely considered in Earth system models and their response to climate change is still largely unknown. To quantify regional and global carbon budgets and climate change effects on carbon pools and carbon fluxes, it is important to account for the coupling between the land, the river, the ocean and the atmosphere. We developed the RIVerine Carbon Model (RivCM), which is directly coupled to the well-established dynamic vegetation and hydrology model LPJmL, in order to account for this large-scale coupling. We evaluate RivCM with observational data and show that some of the values are reproduced quite well by the model, while we see large deviations for other variables. This is mainly caused by some simplifications we assumed. Our evaluation shows that it is possible to reproduce large-scale carbon transport across a river system but that this involves large uncertainties. Acknowledging these uncertainties, we estimate the potential changes in riverine carbon by applying RivCM for climate forcing from five climate models and three CO2 emission scenarios (Special Report on Emissions Scenarios, SRES). We find that climate change causes a doubling of riverine organic carbon in the southern and western basin while reducing it by 20% in the eastern and northern parts. In contrast, the amount of riverine inorganic carbon shows a 2- to 3-fold increase in the entire basin, independent of the SRES scenario. The export of carbon to the atmosphere increases as well, with an average of about 30 %. In contrast, changes in future export of organic carbon to the Atlantic Ocean depend on the SRES scenario and are projected to either decrease by about 8.9% (SRES A1B) or increase by about 9.1% (SRES A2). Such changes in the terrigenous-riverine system could have local and regional impacts on the carbon budget of the whole Amazon basin and parts of the Atlantic Ocean. Changes in riverine carbon could lead to a shift in the riverine nutrient supply and pH, while changes in the exported carbon to the ocean lead to changes in the supply of organic material that acts as a food source in the Atlantic. On larger scales the increased outgassing of CO2 could turn the Amazon basin from a sink of carbon to a considerable source. Therefore, we propose that the coupling of terrestrial and riverine carbon budgets should be included in subsequent analysis of the future regional carbon budget.
Robust appraisals of climate impacts at different levels of global-mean temperature increase are vital to guide assessments of dangerous anthropogenic interference with the climate system. The 2015 Paris Agreement includes a two-headed temperature goal: "holding the increase in the global average temperature to well below 2 degrees C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 degrees C". Despite the prominence of these two temperature limits, a comprehensive overview of the differences in climate impacts at these levels is still missing. Here we provide an assessment of key impacts of climate change at warming levels of 1.5 degrees C and 2 degrees C, including extreme weather events, water availability, agricultural yields, sea-level rise and risk of coral reef loss. Our results reveal substantial differences in impacts between a 1.5 degrees C and 2 degrees C warming that are highly relevant for the assessment of dangerous anthropogenic interference with the climate system. For heat-related extremes, the additional 0.5 degrees C increase in global-mean temperature marks the difference between events at the upper limit of present-day natural variability and a new climate regime, particularly in tropical regions. Similarly, this warming difference is likely to be decisive for the future of tropical coral reefs. In a scenario with an end-of-century warming of 2 degrees C, virtually all tropical coral reefs are projected to be at risk of severe degradation due to temperature-induced bleaching from 2050 onwards. This fraction is reduced to about 90% in 2050 and projected to decline to 70% by 2100 for a 1.5 degrees C scenario. Analyses of precipitation-related impacts reveal distinct regional differences and hot-spots of change emerge. Regional reduction in median water availability for the Mediterranean is found to nearly double from 9% to 17% between 1.5 degrees C and 2 degrees C, and the projected lengthening of regional dry spells increases from 7 to 11%. Projections for agricultural yields differ between crop types as well as world regions. While some (in particular high-latitude) regions may benefit, tropical regions like West Africa, South-East Asia, as well as Central and northern South America are projected to face substantial local yield reductions, particularly for wheat and maize. Best estimate sea-level rise projections based on two illustrative scenarios indicate a 50cm rise by 2100 relative to year 2000-levels for a 2 degrees C scenario, and about 10 cm lower levels for a 1.5 degrees C scenario. In a 1.5 degrees C scenario, the rate of sea-level rise in 2100 would be reduced by about 30% compared to a 2 degrees C scenario. Our findings highlight the importance of regional differentiation to assess both future climate risks and different vulnerabilities to incremental increases in global-mean temperature. The article provides a consistent and comprehensive assessment of existing projections and a good basis for future work on refining our understanding of the difference between impacts at 1.5 degrees C and 2 degrees C warming.
Widespread flooding in June 2013 caused damage costs of (sic)6 to 8 billion in Germany, and awoke many memories of the floods in August 2002, which resulted in total damage of (sic)11.6 billion and hence was the most expensive natural hazard event in Germany up to now. The event of 2002 does, however, also mark a reorientation toward an integrated flood risk management system in Germany. Therefore, the flood of 2013 offered the opportunity to review how the measures that politics, administration, and civil society have implemented since 2002 helped to cope with the flood and what still needs to be done to achieve effective and more integrated flood risk management. The review highlights considerable improvements on many levels, in particular (1) an increased consideration of flood hazards in spatial planning and urban development, (2) comprehensive property-level mitigation and preparedness measures, (3) more effective flood warnings and improved coordination of disaster response, and (4) a more targeted maintenance of flood defense systems. In 2013, this led to more effective flood management and to a reduction of damage. Nevertheless, important aspects remain unclear and need to be clarified. This particularly holds for balanced and coordinated strategies for reducing and overcoming the impacts of flooding in large catchments, cross-border and interdisciplinary cooperation, the role of the general public in the different phases of flood risk management, as well as a transparent risk transfer system. Recurring flood events reveal that flood risk management is a continuous task. Hence, risk drivers, such as climate change, land-use changes, economic developments, or demographic change and the resultant risks must be investigated at regular intervals, and risk reduction strategies and processes must be reassessed as well as adapted and implemented in a dialogue with all stakeholders.
Polymer-dispersed liquid crystals (PDLCs) of ferroelectric poly(vinylidene fluoride-trifluoroethylene) and nematic 4-cyano-4ʹ-n-hexylbiphenyl (6CB) or 4-cyano-4ʹ-n-pentylbiphenyl (5CB) were prepared to study the effect of the remanent polarisation of the polymer on the liquid crystal alignment. We measured the macroscopic alignment of the liquid crystal molecules in the thickness direction by means of Infrared Transition-Moment Orientational Analysis. Electrical poling at 100 V/µm caused an increased order parameter up to 0.15. After subsequent annealing above the nematic-to-isotropic phase-transition temperature, the order parameter was reduced to 0.02. Nevertheless, the order parameter was still higher than for non-poled film indicating a slight orientation in thickness direction. Both values are lower than those expected from model calculations. In agreement with dielectric measurements, we attribute this result to the shielding effect of mobile charge carriers within the liquid crystal inclusions.