CityScapeLab Berlin: A Research Platform for Untangling Urbanization Effects on Biodiversity

Urban biodiversity conservation requires an understanding of how urbanization modulates biodiversity patterns and the associated ecosystem services. While important advances have been made in the conceptual development of urban biodiversity research over the last decades, challenges remain in understanding the interactions between different groups of taxa and the spatiotemporal complexity of urbanization processes. The CityScapeLab Berlin is a novel experimental research platform that allows the testing of theories on how urbanization affects biodiversity patterns and biotic interactions in general and the responses of species of conservation interest in particular. We chose dry grassland patches as the backbone of the research platform because dry grasslands are common in many urban regions, extend over a wide urbanization gradient, and usually harbor diverse and self-assembled communities. Focusing on a standardized type of model ecosystem allowed the urbanization effects on biodiversity to be unraveled from effects that would otherwise be masked by habitat- and land-use effects. The CityScapeLab combines different types of spatiotemporal data on (i) various groups of taxa from different trophic levels, (ii) environmental parameters on different spatial scales, and (iii) on land-use history. This allows for the unraveling of the effects of current and historical urban conditions on urban biodiversity patterns and the related ecological functions.BMBF, 01LC1501, BIBS-Verbund: Bridging in Biodiversity Science (BIBS

Emerging Urban Forests: Opportunities for Promoting the Wild Side of the Urban Green Infrastructure

Many cities aim to increase urban forest cover to benefit residents through the provision of ecosystem services and to promote biodiversity. As a complement to traditional forest plantings, we address opportunities associated with “emerging urban forests” (i.e., spontaneously developing forests in cities) for urban biodiversity conservation. We quantified the area of successional forests and analyzed the species richness of native and alien plants and of invertebrates (carabid beetles, spiders) in emerging forests dominated by alien or native trees, including Robinia pseudoacacia, Acer platanoides, and Betula pendula. Emerging urban forests were revealed as shared habitats of native and alien species. Native species richness was not profoundly affected by the alien (co-)dominance of the canopy. Instead, native and alien plant species richnesses were positively related. Numbers of endangered plants and invertebrates did not differ between native- and alien-dominated forest patches. Patterns of tree regeneration indicate different successional trajectories for novel forest types. We conclude that these forests (i) provide habitats for native and alien species, including some endangered species, (ii) allow city dwellers to experience wild urban nature, and (iii) support arguments for adapting forests to dynamic urban environments. Integrating emerging urban forests into the urban green infrastructure is a promising pathway to sustainable cities and can complement traditional restoration or greening approaches.BMBF, 01LC1501, Bridging in Biodiversity Science (BIBS

High-Temperature Heat Pump for Wellness Applications Using CO2 as a Refrigerant

Building technology recently has been affected by great innovations to reduce energy demand and to enable self-sufficient operation. To test innovations and prove practicality, EMPA has built a research building called NEST, where different demonstration projects from the building industry can be integrated and scientifically monitored. Furthermore, the sector of wellness applications shows significant potential for improving energy efficiency. Usually, spa facilities such as saunas and steam baths are based on direct electric or fossil heating which is extremely energy intensive and results in high operating costs. In order to establish a more energy efficient technology to provide heat to wellness areas, the present work proposes the usage of a high temperature heat pump with CO2 as a refrigerant. Carbon dioxide is currently favored by many heat pump applications due to the demand for low-GWP refrigerants with non-toxic and non-flammable properties. High-temperature heat pumps with CO2 as a refrigerant are already available on the market and reach supply temperatures typically up to 100 °C. Wellness applications require temperatures up to 130 °C on the supplier side, which requires new system design. On the consumption side, the heat will be used on a wide variety of temperature levels considering different saunas, showers and space heating. In this context, a stratified storage system ensures the heat output on the desired temperature level. Therefore, the heat exchanger unit as well as the operating range of the heat pump are the major challenges. In Coorporation with Scheco AG, a new CO2 refrigerant system has been designed and set up as a part of EMPA research building by means of a pilot installation including different saunas, steam bath and showers. Measurements will be performed as soon as possible to start the optimization process of the system

Phenology of grassland plants responds to urbanization

Understanding phenological responses of plants to changing temperatures is important because of multiple associated ecological consequences. Cities with their urban heat island can be used as laboratories to study phenological adaptation to climate change. However, previous phenology studies focused on trees and did not disentangle the role of micro-climate and urban structures. We studied reproductive phenology of dry grassland species in response to micro-climate and urbanization in Berlin, Germany. Phenological stages were recorded weekly at the individual plant level for five native grassland species across 30 dry grassland sites along an urbanization and temperature gradient. We estimated 50% onset probabilities for flowering and seed maturation of populations, and analysed variation in onset dates using regression models. Early flowering species significantly advanced flowering phenology with increasing mean air temperature but were little influenced by urbanization. By contrast, late-flowering species showed significant phenological responses to both air temperature and urbanization, possibly because micro-climate was most affected by urbanization in late summer. Surprisingly, not all grassland species showed an advanced phenology with increasing intensity of urbanization. This contradicts observed patterns for urban trees, indicating that phenological shifts in urban areas cannot be generalized from the observation of one growth form or taxonomic group. Growth form appears as a possible determinant of phenological responses. Results suggest that the phenology of dry grassland species may directly respond to the urban heat island, albeit with variable direction and magnitude. This has implications for ecosystem services, shifted allergy seasons, changes of biogeochemical cycles and potential ecological mismatches

Ligand-binding and -scavenging of the chemerin receptor GPR1

Tight regulation of cytokines is essential for the initiation and resolution of inflammation. Chemerin, a mediator of innate immunity, mainly acts on chemokine-like receptor 1 (CMKLR1) to induce the migration of macrophages and dendritic cells. The role of the second chemerin receptor, G protein-coupled receptor 1 (GPR1), is still unclear. Here we demonstrate that GPR1 shows ligand-induced arrestin3 recruitment and internalization. The chemerin C-terminus triggers this activation by folding into a loop structure, binding to aromatic residues in the extracellular loops of GPR1. While this overall binding mode is shared between GPR1 and CMKLR1, differences in their respective extracellular loop 2 allowed for the design of the first GPR1-selective peptide. However, our results suggest that ligand-induced arrestin recruitment is not the only mode of action of GPR1. This receptor also displays constitutive internalization, which allows GPR1 to internalize inactive peptides efficiently by an activation-independent pathway. Our results demonstrate that GPR1 takes a dual role in regulating chemerin activity: as a signaling receptor for arrestin-based signaling on one hand, and as a scavenging receptor with broader ligand specificity on the other. Graphic abstractDeutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Universität Leipzig (1039)Peer Reviewe

Measuring Lensing Magnification of Quasars by Large Scale Structure using the Variability-Luminosity Relation

We introduce a technique to measure gravitational lensing magnification using the variability of type I quasars. Quasars' variability amplitudes and luminosities are tightly correlated, on average. Magnification due to gravitational lensing increases the quasars' apparent luminosity, while leaving the variability amplitude unchanged. Therefore, the mean magnification of an ensemble of quasars can be measured through the mean shift in the variability-luminosity relation. As a proof of principle, we use this technique to measure the magnification of quasars spectroscopically identified in the Sloan Digital Sky Survey, due to gravitational lensing by galaxy clusters in the SDSS MaxBCG catalog. The Palomar-QUEST Variability Survey, reduced using the DeepSky pipeline, provides variability data for the sources. We measure the average quasar magnification as a function of scaled distance (r/R200) from the nearest cluster; our measurements are consistent with expectations assuming NFW cluster profiles, particularly after accounting for the known uncertainty in the clusters' centers. Variability-based lensing measurements are a valuable complement to shape-based techniques because their systematic errors are very different, and also because the variability measurements are amenable to photometric errors of a few percent and to depths seen in current wide-field surveys. Given the data volume expected from current and upcoming surveys, this new technique has the potential to be competitive with weak lensing shear measurements of large scale structure.Comment: Accepted for publication in Ap

Golden gravitational lensing systems from the Sloan Lens ACS Survey. II. SDSS J1430+4105: A precise inner total mass profile from lensing alone

We study the SLACS strong lensing system SDSSJ1430+4105 at z=0.285. The lensed source (z=0.575) of this system has a complex morphology with several subcomponents. Its subcomponents span a radial range from 4 to 10kpc in the lens plane. Therefore we can constrain the slope of the total projected mass profile around the Einstein radius (R_E) from lensing alone. We measure a density profile that is slightly but not significantly shallower than isothermal at R_E. We decompose the mass of the lensing galaxy into a de Vaucouleurs (deV) component to trace the stars and an additional dark component. The spread of multiple image components over a large radial range also allows us to determine the amplitude of the deV and dark matter components separately. We get a mass to light ratio of M_deV/L_B~5.5\pm1.5M/L_sun,B and a dark matter fraction within R_E of ~20 to 40%. Modelling the star formation history assuming composite stellar populations at solar metallicity to the galaxy's photometry yields a mass to light ratio of M_star,salp/L_B~4.0_{-1.3}^{+0.6}M/L_sun,B and M_star,chab/L_B~2.3_{-0.8}^{+0.3}M/L_sun,B for Salpeter and Chabrier IMFs, respectively. Hence, the mass to light ratio derived from lensing is more Salpeter-like, in agreement with results for massive Coma galaxies and other nearby massive early type galaxies. We examine the consequences of the galaxy group in which the lensing galaxy is embedded, showing that it has little influence on the mass to light ratio obtained for the deV component of the lensing galaxy. Finally, we decompose the projected, azimuthally averaged 2D density distribution of the deV and dark matter component of the lensing signal into spherically averaged 3D density profiles. We can show that the 3D dark and luminous matter density within R_E~0.6R_eff of this SLACS galaxy is similar to the values of Coma galaxies with the same velocity dispersions.Comment: 24 pages, 21 figures, 11 tables, accepted for publication by MNRA

Centre de recherches historiques

Marie-Anne Polo de Beaulieu, chargée de recherche au CNRSJacques Berlioz, directeur de recherche au CNRS Les exempla médiévaux. Perspectives comparatistes Le séminaire a poursuivi la démarche comparatiste initiée l’année précédente. L’intérêt du groupe s’est d’abord porté sur le statut de l’anecdote exemplaire dans les Mille et une nuits dont l’indexation, en cours de réalisation, a été présentée par Claude Bremond. Deux séances ont été consacrées au statut de l’exemplaire dans la littérature..