Object Image Linking of Earth Orbiting Objects in the Presence of Cosmics

In survey series of unknown Earth orbiting objects, no a priori orbital elements are available. In surveys of wide field telescopes possibly many nonresolved object images are present on the single frames of the series. Reliable methods have to be found to associate the object images stemming from the same object with each other, so-called linking. The presence of cosmic ray events, so-called Cosmics, complicates reliable linking of non-resolved images. The tracklets of object images allow to extract exact positions for a first orbit determination. A two step method is used and tested on observation frames of space debris surveys of the ESA Space Debris Telescope, located on Tenerife, Spain: In a first step a cosmic filter is applied in the single observation frames. Four different filter approaches are compared and tested in performance. In a second step, the detected object images are linked on observation series based on the assumption of a linear accelerated movement of the objects over the frame during the series, which is updated with every object image, that could be successfully linked.Comment: Accepted for Publication; Advances in Space Research, 201

Simulation of water flow in the branched tree architecture.

The model HYDRA, which simulates water flow in the branched tree architecture, is characterized. Empirical studies of the last decades give strong evidence for a close structure-function linkage in the case of tree water flow. Like stomatal regulation, spatial patterns of leaf specific conductivity can be regarded as a strategy counteracting conductivity losses which may arise under drought. Branching-oriented water flow simulation may help to understand how damaging and compensating mechanisms interact within the hydraulic network of trees. Furthermore, a coupling of hydraulic to morphological modelling is a prerequisite if water flow shall be linked to other processes. Basic assumptions of the tree water flow model HYDRA are mass conservation, Darcy’s law and the spatial homogeneity of capacitance and axial conductivity. Soil water potential is given as a one-sided border condition. Water flow is driven by transpiration. For unbranched regions these principles are condensed to a nonlinear diffusion equation, which serves as a continuous reference for the discrete method tailored to the specific features of the hydraulic network. The mathematical derivation and model tests indicate that the realization of the basic assumptions is reproducible and sufficiently exact. Moreover, structure and function are coupled in a flexible and computationally efficient manner. Thus, HYDRA may serve as a tool for the comparative study of different tree architectures in terms of hydraulic function

Chicken γδ T cells proliferate upon IL-2 and IL-12 treatment and show a restricted receptor repertoire in cell culture

In chickens, γδ T cells represent a large fraction of peripheral T cells; however, their function remains largely unknown. Here, we describe the selective in vitro expansion of γδ T cells from total splenocytes by stimulation with the cytokines IL-2 and IL-12. Under these conditions, γδ T cells proliferated preferentially and reached frequencies of >95% within three weeks. Although IL-2 alone also triggered proliferation, an increased proliferation rate was observed in combination with IL-12. Most of the expanded cells were γδ TCR and CD8 double-positive. Splenocytes sorted into TCR1+CD8+, TCR1highCD8−, and TCR1lowCD8− subsets proliferated well upon dual stimulation with IL-2/IL-12, indicating that none of the three γδ T cell subsets require bystander activation for proliferation. TCR1+CD8+ cells maintained CD8 surface expression during stimulation, whereas CD8− subpopulations showed varied levels of CD8 upregulation, with the highest upregulation observed in the TCR1high subset. Changes in the γδ T-cell receptor repertoire during cell culture from day 0 to day 21 were analyzed by next-generation sequencing of the γδ variable regions. Overall, long-term culture led to a restricted γ and δ chain repertoire, characterized by a reduced number of unique variable region clonotypes, and specific V genes were enriched at day 21. On day 0, the δ chain repertoire was highly diverse, and the predominant clonotypes differed between animals, while the most frequent γ-chain clonotypes were shared between animals. However, on day 21, the most frequent clonotypes in both the γ and δ chain repertoires were different between animals, indicating that selective expansion of dominant clonotypes during stimulation seems to be an individual outcome. In conclusion, IL-2 and IL-12 were sufficient to stimulate the in vitro outgrowth of γδ T cells. Analyses of the TCR repertoire indicate that the culture leads to an expansion of individual T cell clones, which may reflect previous in vivo activation. This system will be instrumental in studying γδ T cell function

Bioraps

Die Nachfrage in der Schweiz nach kaltgepresstem Biorapsspeiseöl ist gut. Betriebswirtschaftlich ist der Rapsanbau jenem von Biobrotgetreide gleichzustellen, vorausgesetzt die Kultur gelingt. Denn der biologische Anbau von Raps stellt eine Herausforderung dar. Das Merkblatt liefert auf fünf Seiten die wichtigsten Informationen zu Anbau und Vermarktung der Kultur

Influence of the Side Chain Structure on the Electronic Structure and Self-Organization Properties of Low Band Gap Polymers

The properties of low band gap polymers in devices such as solar cells are strongly influenced by their morphology and ability of self-organization in thin films and interface properties. We study the influence of alkyl and alkoxy side chain position for four conjugated, alternating oligothiophene-benzothiadiazole copolymers on the molecular orientation in thin films and electronic interface properties using photoemission, X-ray absorption spectroscopy (XAS) at the sulfur K edge, and polarization modulation-infrared reflection–absorption spectroscopy (PMIRRAS). The interface charge transfer (ICT) model is used to explain interface properties of the polymers on substrates with different work functions. We find that the position of the side chains has a significant influence on the orientation and thus on self-organization properties of the polymers in thin films, whereas the electronic structure is less affected. The preferred molecular orientation is further affected by annealing, leading to a higher degree of ordering. Results from complementary methods with different surface sensitivities (XAS in total electron yield and fluorescence mode and PMIRRAS) are discussed

The Fluvial and Water-Rich History of Northern Xanthe Terra: A Reference for the ExoMars Landing Site

We produced a geomorphological map of a study area in northern Xanthe Terra, which shares several characteristics with the ExoMars Rover landing site

Ein neuer Gesellschaftsvertrag für eine nachhaltige Landwirtschaft

Die Landwirtschaft in Deutschland, Europa und weltweit befindet sich in einem dramatischen Umbruchprozess. Einerseits bieten Liberalisierung und Marktöffnung, neue technologische Entwicklungen, die wachsende Weltbevölkerung und neue Kundenwünsche vielen landwirtschaftlichen Betrieben neue Möglichkeiten. Andererseits stehen viele Landwirtinnen und Landwirte in internationaler Konkurrenz, sind zum betrieblichen Wachstum mit hohem Investitionsrisiko gezwungen, sind Teil strikt regulierter Wertschöpfungsketten und müssen steigenden gesellschaftlichen Ansprüchen genügen. Zugleich machen sich viele Menschen Sorgen, dass die Prozesse der Rationalisierung und Modernisierung der landwirtschaftlichen Produktion auf Kosten von Natur-, Umwelt- und Tierschutz gehen. Auf vielen Ebenen wird daher bereits nach einer neuen Verständigung darüber gesucht, was die Gesellschaft von der Landwirtschaft erwartet, und welche Unterstützung die Landwirtinnen und Landwirte im Gegenzug dafür erwarten dürfen. Vor diesem Hintergrund entwickelt das vorliegende Open Access-Buch eine wissenschaftlich fundierte Kritik der Umweltauswirkungen der Landwirtschaft und der politischen Logik der Agrarpolitik. Es präsentiert ein neues Leitbild mit konkreten Indikatoren sowie alternative strategische Handlungsoptionen. Die umfassende Analyse wird zu einem Vorschlag für eine neue Architektur der europäischen Agrarpolitik gebündelt, die eine breite Diskussion um einen Neuen Gesellschaftsvertrag für die Landwirtschaft in Deutschland und Europa anstoßen soll

The Epstein-Barr Virus G-Protein-Coupled Receptor Contributes to Immune Evasion by Targeting MHC Class I Molecules for Degradation

Epstein-Barr virus (EBV) is a human herpesvirus that persists as a largely subclinical infection in the vast majority of adults worldwide. Recent evidence indicates that an important component of the persistence strategy involves active interference with the MHC class I antigen processing pathway during the lytic replication cycle. We have now identified a novel role for the lytic cycle gene, BILF1, which encodes a glycoprotein with the properties of a constitutive signaling G-protein-coupled receptor (GPCR). BILF1 reduced the levels of MHC class I at the cell surface and inhibited CD8+ T cell recognition of endogenous target antigens. The underlying mechanism involves physical association of BILF1 with MHC class I molecules, an increased turnover from the cell surface, and enhanced degradation via lysosomal proteases. The BILF1 protein of the closely related CeHV15 c1-herpesvirus of the Rhesus Old World primate (80% amino acid sequence identity) downregulated surface MHC class I similarly to EBV BILF1. Amongst the human herpesviruses, the GPCR encoded by the ORF74 of the KSHV c2-herpesvirus is most closely related to EBV BILF1 (15% amino acid sequence identity) but did not affect levels of surface MHC class I. An engineered mutant of BILF1 that was unable to activate G protein signaling pathways retained the ability to downregulate MHC class I, indicating that the immune-modulating and GPCR-signaling properties are two distinct functions of BILF1. These findings extend our understanding of the normal biology of an important human pathogen. The discovery of a third EBV lytic cycle gene that cooperates to interfere with MHC class I antigen processing underscores the importance of the need for EBV to be able to evade CD8+ T cell responses during the lytic replication cycle, at a time when such a large number of potential viral targets are expressed