The consequences of urban sprawl in a context of decline: the case of Leipzig

--

Breaks in interstellar spectra of positrons and electrons derived from time-dependent AMS data

Until fairly recently, it was widely accepted that local cosmic ray spectra were largely featureless power laws, containing limited information on their acceleration and transport. This viewpoint is currently being revised in the light of evidence for a variety of spectral breaks in the fluxes of cosmic ray nuclei. Here, we focus on cosmic ray electrons and positrons which at the highest energies must be of local origin due to strong radiative losses. We consider a pure diffusion model for their Galactic transport and determine its free parameters by fitting data in a wide energy range: measurements of the interstellar spectrum by Voyager at MeV energies, radio synchrotron data (sensitive to GeV electrons and positrons) and local observations by AMS up to ~ 1 TeV. For the first time, we also model the time-dependent fluxes of cosmic ray electrons and positrons at GeV energies recently presented by AMS, treating solar modulation in a simple extension of the widely used force-field approximation. We are able to reproduce all the available measurements to date. Our model of the interstellar spectrum of cosmic ray electrons and positrons requires the presence of a number of spectral breaks, both in the source spectra and the diffusion coefficients. While we remain agnostic as to the origin of these spectral breaks, their presence will inform future models of the microphysics of cosmic ray acceleration and transport.Comment: 19 pages, 9 figures; submitted to PR

Colonization of an empty island:how does a plant with a plastic gender system respond?

<i>Honckenya peploides</i> is the most common plant species on the island of Surtsey. It arrived in 1967 and after a juvenile period of 4 years it produced seeds and had increased its number from below 100 to several millions. Most populations had the individuals distributed in a regular or random pattern, suggesting that intraspecific competition is important. <i>H. peploides</i> has a subdioecious reproductive system consisting of pistillate plants producing capsules, and staminate plants delivering pollen. Some of the latter are in addition producing capsules and are denoted hermaphrodites. Populations at the south coast of Iceland had around equal numbers of pistillate and staminate plants. At Surtsey we found more pistillate plants, probably due to their higher water stress tolerance. We also found a tendency to a higher frequency of hermaphrodite plants with a higher number of seeds per capsule compared to populations at the south coast of Iceland and the nearby island of Heimaey. We suggest that this arises from the time right after the colonization of Surtsey where population size was small and the small generalist pollinators were not able to deposit sufficient pollen on pistillate plants, causing the hermaphrodites to have an advantage by being able to set seed after selfing. The result of this initial advantage of the hermaphrodites in combination with the inheritance of the sexes can still be seen due to the longevity of individuals. A generalized account of the colonization history of <i>H. peploides</i> is given

Interplay of magnetism and superconductivity in EuFe2_{2}(As1−x_{1-x}Px_{x})2_{2} single crystals probed by muon spin rotation and 57{}^{57}Fe M\"ossbauer spectroscopy

We present our results of a local probe study on EuFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ single crystals with $x$=0.13, 0.19 and 0.28 by means of muon spin rotation and ${}^{57}$Fe M\"ossbauer spectroscopy. We focus our discussion on the sample with $x$=0.19 viz. at the optimal substitution level, where bulk superconductivity ($T_{\text{SC}}=28$ K) sets in above static europium order ($T^{\text{Eu}}=20$K) but well below the onset of the iron antiferromagnetic (AFM) transition ($\sim$100 K). We find enhanced spin dynamics in the Fe sublattice closely above $T_{\text{SC}}$ and propose that these are related to enhanced Eu fluctuations due to the evident coupling of both sublattices observed in our experiments.Comment: Contribution to the 13th International Conference on Muon Spin Rotation, Relaxation and Resonance (MuSR2014

Prediction of Gaps in Automated Tape Laying and Their Influence on Porosity in Consolidated Laminates

An efficient way to reduce direct operating costs in aerospace applications is to lower the overall weight. In this context, thermoplastic composites offer a high potential for weight reduction. However, their application requires time and cost-optimized process technologies. Thermoplastic tape laying with subsequent out-of-autoclave consolidation represents such a process technology. Typical process chains consist of several automated steps that can influence the component’s quality. Hence, a cross-process approach is applied to identify relevant process parameters. This paper focuses on minimizing the gaps between parallel-placed tapes and thereby reducing their influence on the laminate’s porosity. A geometrical model is developed and validated to predict the maximum gap sizes for a tape-laying process as a function of process accuracy, material accuracy, and process parameters. Based on this, a methodological approach is presented to minimize the influence of gaps on porosity. It is validated using automated tape laying and a novel low-pressure consolidation process. The findings make an important contribution to understanding the development of porosity along the process chain for the manufacture of thermoplastic composites for aerospace applications. It can be shown that the approach enables the prediction of gap sizes and allows to minimize their influence on porosity

Strategischer Hasstransfer in der arabischsprachigen Rundfunkpropaganda NS-Deutschlands

Die nationalsozialistische Rundfunkpropaganda auf Arabisch spielte während des Zweiten Weltkrieges eine besondere Rolle innerhalb der deutschen Auslandspropaganda. Die von NS-Seite als Gemeinsamkeiten identifizierten Feindbilder der europäischen Kolonialmächte, des Bolschewismus und des Judentums bildeten zusammen mit einer nationalsozialistischen Bewunderung für den Islam die Grundlage der inhaltlichen Ausrichtung. Die Zuständigkeiten bezüglich der Auslandspropaganda innerhalb des NS-Staates waren dabei zwischen Propagandaministerium und Auswärtigem Amt umkämpft, was zu einer teils inkohärenten Propagandastrategie führte. Zur Steigerung der Authentizität wurde großer Wert auf Muttersprachler wie den Iraker Yunus Bahri gelegt. Konzeptionell bestimmten jedoch deutsche Orientalisten und Propagandisten das Programm. Anhand der „Neu-Arabischen Stilproben“ des Arabisten Gerhard Rott lässt sich ein einzigartiger Einblick in die Arbeitsweise und Inhalte des ersten Jahres der arabischsprachigen Sendungen gewinnen. Die Rolle von arabischen Exilpolitikern im Dienst der NS-Propaganda, wie dem Mufti von Jerusalem, war dabei geringer als oftmals dargestellt. Die deutschen Sender agierten nach der vom BBC-Mitarbeiter Sefton Delmer geprägten Definition der „weißen“ und der „schwarzen“ Propaganda und verfolgten mit den Stationen Radio Berlin und „Concordia A“ unterschiedliche Strategien. Anhand der Radikalisierung des Programms und der zunehmenden Hetze gegen Juden sowie der Instrumentalisierung des Islam lässt sich veranschaulichen, wie die Dynamik des Kriegsverlaufes sowie die fortschreitende Judenvernichtung in Europa auch die deutschen Beeinflussungsversuche außerhalb Europas prägten. Abschließend wird ein Versuch unternommen, auf die Wirkung der Propaganda über 1945 hinaus in der arabisch-islamischen Welt einzugehen

Ward identities in N=1\mathcal{N}=1 supersymmetric SU(3) Yang-Mills theory on the lattice

The introduction of a space-time lattice as a regulator of field theories breaks symmetries associated with continuous space-time, i.e.\ Poincar{\'e} invariance and supersymmetry. A non-zero gluino mass in the supersymmetric Yang-Mills theory causes an additional soft breaking of supersymmetry. We employ the lattice form of SUSY Ward identities, imposing that their continuum form would be recovered when removing the lattice regulator, to obtain the critical hopping parameter where broken symmetries can be recovered.Comment: Presented at Lattice 2017, the 35th International Symposium on Lattice Field Theory at Granada, Spain (18-24 June 2017

Challenging incompleteness of performance requirements by sentence patterns

Performance requirements play an important role in software development. They describe system behavior that directly impacts the user experience. Specifying performance requirements in a way that all necessary content is contained, i.e., the completeness of the individual requirements, is challenging, yet project critical. Furthermore, it is still an open question, what content is necessary to make a performance requirement complete. To address this problem, we introduce a framework for specifying performance requirements. This framework (i) consists of a unified model derived from existing performance classifications, (ii) denotes completeness through a content model, and (iii) is operationalized through sentence patterns. We evaluate both the applicability of the framework as well as its ability uncover incompleteness with performance requirements taken from 11 industrial specifications. In our study, we were able to specify 86% of the examined performance requirements by means of our framework. Furthermore, we show that 68% of the specified performance requirements are incomplete with respect to our notion of completeness. We argue that our framework provides an actionable definition of completeness for performance requirements

Behavioral Barriers and the Socioeconomic Gap in Child Care Enrollment

Children with lower socioeconomic status (SES) tend to benefit more from early child care, but are substantially less likely to be enrolled. We study whether reducing behavioral barriers in the application process increases enrollment in child care for lower-SES children. In our RCT in Germany with highly subsidized child care (n > 600), treated families receive application information and personal assistance for applications. For lower-SES families, the treatment increases child care application rates by 21 pp and enrollment rates by 16 pp. Higher-SES families are not affected by the treatment. Thus, alleviating behavioral barriers closes half of the SES gap in early child care enrollment

Development of a reactive polyurethane foam system for the direct sandwich composite molding (D-SCM) process

Sandwich structures utilize the geometric stiffening effect by increasing the area moment of inertia. This reduces carbon fiber (CF) material within CF-reinforced plastic (CFRP) components, and thus, the CO2 footprint. A suitable material combination for lightweight design is the use of continuous fiber-reinforced face sheets with a light foam core. CFRP sandwich structures with foam core are manufactured by combining a prefabricated foam core with fiber-reinforced cover layers in a two-step press process. Besides the reduction of the used CFRP material, more efficient manufacturing processes are needed. The aim of this paper is to develop a novel polyurethane foam system to enable the direct sandwich composite molding (D‑SCM) process for the production of CFRP sandwich structures by utilizing the resulting foaming pressure during the reactive polyurethane (PUR) foam system expansion for the impregnation of the CF reinforced face sheets. The developed formulation enables D-SCM structures with 150–250 kg/m3 foam density and 44–47.5% fiber volume content, based on a preliminary evaluation