Mapping mental barriers that prevent the use of neighborhood green spaces

This article was supported by the German Research Foundation (DFG) and the Open Access Publication Fund of Humboldt-Universität zu Berlin.In comparison to the study of green space use, the study of its non-use or rejection is greatly understudied. Neighborhood managers and members of local gardening initiatives of Halle-Newtown, Germany, state that residents ignore local green-blue infrastructure (GBI) for recreational use. Halle-Newtown is a former showcase, large prefabricated socialist housing estate that is now facing an increase of households deprived in multiple ways. We are interested in the question of why people of Halle-Newtown refuse to use local GBI. In order to uncover potential barriers to the enjoyment of the ecosystem service benefits of local GBI, we have chosen the method of mental mapping to explore place attachment in Halle-Newtown. In summer 2018, about 100 residents of Halle-Newtown described the places they prefer when relaxing from a stressful and hot summer day. The results were surprising. Local GBI, be it created in socialist times or recently, was completely absent from their mental maps. Instead, people would overcome longer distances and cover higher costs to reach central green spaces. Tacit knowledge, namely the untold general rejection of the entire neighborhood by the residents, was found to be the deeper reason behind non-use of GBI and missing place attachment. The results uncovered that both neighborhood neglect and the multi-scalar character of urban recreational ideas/behavior are factors that help us to understand non-use of urban GBI, two key insights for urban planning.Peer Reviewe

Control of Uterine Microenvironment by Foxp3+ Cells Facilitates Embryo Implantation

Implantation of the fertilized egg into the maternal uterus depends on the fine balance between inflammatory and anti-inflammatory processes. Whilst regulatory T cells (Tregs) are reportedly involved in protection of allogeneic fetuses against rejection by the maternal immune system, their role for pregnancy to establish, e.g., blastocyst implantation, is not clear. By using 2-photon imaging we show that Foxp3(+) cells accumulated in the mouse uterus during the receptive phase of the estrus cycle. Seminal fluid further fostered Treg expansion. Depletion of Tregs in two Foxp3.DTR-based models prior to pairing drastically impaired implantation and resulted in infiltration of activated T effector cells as well as in uterine inflammation and fibrosis in both allogeneic and syngeneic mating combinations. Genetic deletion of the homing receptor CCR7 interfered with accumulation of Tregs in the uterus and implantation indicating that homing of Tregs to the uterus was mediated by CCR7. Our results demonstrate that Tregs play a critical role in embryo implantation by preventing the development of a hostile uterine microenvironment.DFG grants: (ZE526/4-2, SFB854TP7), Wilhelm Sander Stiftung Germany grant: (2009.022.1), Helmholtz Alliance for Immunotherapy, FCT, Medical Faculty Otto-von-Guericke University PhD grant

Ultrafast nuclear dynamics of the acetylene cation C2H2+ and its impact on the infrared probe pulse induced C–H bond breaking efficiency

The ultrafast nuclear dynamics of the acetylene cation C2H2+ following photoionization of the neutral molecule is investigated using an extreme-ultraviolet pump/infrared probe setup. The observed modulation of the C2H+ fragment ion yield with pump–probe delay is related to structural changes induced by the extreme-ultraviolet pump pulse taking place on the femtosecond timescale. High-level simulations suggest that the trans-bending and C–C bond stretching motion of the C2H2+ cation govern the observed interaction with the infrared pulse. Depending on the molecular configuration at arrival of the infrared pulse, it either transfers population to higher-lying states or to the C2H2+ ground state, thereby enhancing or lowering the C2H+ yield. Our ultrafast pump–probe scheme can thus be used to track excited state nuclear dynamics with a resolution of a few femtoseconds, leading the way to studying fast dynamics also in larger hydrocarbon molecules.ISSN:1463-9084ISSN:1463-907

Forschendes Lernen in der Sekundarstufe II. Konzepte und erste Ergebnisse aus dem Oberstufen-Kolleg

Graf C, Inger G, Jacobs N, et al. Forschendes Lernen in der Sekundarstufe II. Konzepte und erste Ergebnisse aus dem Oberstufen-Kolleg. Presented at the Fachtagung Zur Erforschung Forschenden Lernens, Bielefed

Few-Femtosecond Dynamics of Free-Free Opacity in Optically Heated Metals

Interaction of light with an excited free-electron gas is a fundamental process spanning a large variety of fields in physics. The advent of femtosecond laser pulses and extreme-ultraviolet sources allowed one to put theoretical models to the test. Recent experimental and theoretical investigations of nonequilibrium aluminum, which is considered to be a good real-world representation of an ideal free-electron metal, showed that, despite significant progress, the transient hot-electron/cold-ion state is not well understood. In particular, the role of plasmon broadening, screening, and electron degeneracy remains unclear. Here, we experimentally investigate the free-free opacity in aluminum on the few-femtosecond timescale at laser intensities close to the damage threshold. Few-femtosecond time resolution allows us to track the purely electronic contribution to nonequilibrium absorption and unambiguously separate it from the slower lattice contribution. We support the experiments with ab initio calculations and a nearly free electron model in the Sommerfeld expansion. We find that the simplest independent-particle model with a fixed band structure is sufficient to explain the experimental findings without the need to include changes in screening or electron scattering, contrasting previous observations in 3d transition metals. We further find that electronic heating of a free-electron gas shifts the spectral weight of the absorption to higher photon energies, and we are able to distinguish the influence of the population change and the chemical potential shift based on the comparison of ab initio calculations to a simplified free-electron model. Our findings provide a benchmark for further investigations and modeling of dense nonequilibrium plasma under even more extreme conditions.ISSN:2160-330

Few-Femtosecond Dynamics of Free-Free Opacity in Optically Heated Metals

Interaction of light with an excited free-electron gas is a fundamental process spanning a large variety of fields in physics. The advent of femtosecond laser pulses and extreme-ultraviolet sources allowed one to put theoretical models to the test. Recent experimental and theoretical investigations of nonequilibrium aluminum, which is considered to be a good real-world representation of an ideal free-electron metal, showed that, despite significant progress, the transient hot-electron/cold-ion state is not well understood. In particular, the role of plasmon broadening, screening, and electron degeneracy remains unclear. Here, we experimentally investigate the free-free opacity in aluminum on the few-femtosecond timescale at laser intensities close to the damage threshold. Few-femtosecond time resolution allows us to track the purely electronic contribution to nonequilibrium absorption and unambiguously separate it from the slower lattice contribution. We support the experiments with ab initio calculations and a nearly free electron model in the Sommerfeld expansion. We find that the simplest independent-particle model with a fixed band structure is sufficient to explain the experimental findings without the need to include changes in screening or electron scattering, contrasting previous observations in 3d transition metals. We further find that electronic heating of a free-electron gas shifts the spectral weight of the absorption to higher photon energies, and we are able to distinguish the influence of the population change and the chemical potential shift based on the comparison of ab initio calculations to a simplified free-electron model. Our findings provide a benchmark for further investigations and modeling of dense nonequilibrium plasma under even more extreme conditions.publishe