Detection of a flow induced magnetic field eigenmode in the Riga dynamo facility

In an experiment at the Riga sodium dynamo facility, a slowly growing magnetic field eigenmode has been detected over a period of about 15 seconds. For a slightly decreased propeller rotation rate, additional measurements showed a slow decay of this mode. The measured results correspond satisfactory with numerical predictions for the growth rates and frequencies

Quantitative analysis of numerical estimates for the permeability of porous media from lattice-Boltzmann simulations

During the last decade, lattice-Boltzmann (LB) simulations have been improved to become an efficient tool for determining the permeability of porous media samples. However, well known improvements of the original algorithm are often not implemented. These include for example multirelaxation time schemes or improved boundary conditions, as well as different possibilities to impose a pressure gradient. This paper shows that a significant difference of the calculated permeabilities can be found unless one uses a carefully selected setup. We present a detailed discussion of possible simulation setups and quantitative studies of the influence of simulation parameters. We illustrate our results by applying the algorithm to a Fontainebleau sandstone and by comparing our benchmark studies to other numerical permeability measurements in the literature.Comment: 14 pages, 11 figure

Lipid Signaling via Pkh1/2 Regulates Fungal CO 2 Sensing through the Kinase Sch9.

Adaptation to alternating CO2 concentrations is crucial for all organisms. Carbonic anhydrases—metalloenzymes that have been found in all domains of life—enable fixation of scarce CO2 by accelerating its conversion to bicarbonate and ensure maintenance of cellular metabolism. In fungi and other eukaryotes, the carbonic anhydrase Nce103 has been shown to be essential for growth in air (~0.04% CO2). Expression of NCE103 is regulated in response to CO2 availability. In Saccharomyces cerevisiae, NCE103 is activated by the transcription factor ScCst6, and in Candida albicans and Candida glabrata, it is activated by its homologues CaRca1 and CgRca1, respectively. To identify the kinase controlling Cst6/Rca1, we screened an S. cerevisiae kinase/phosphatase mutant library for the ability to regulate NCE103 in a CO2-dependent manner. We identified ScSch9 as a potential ScCst6-specific kinase, as the sch9? mutant strain showed deregulated NCE103 expression on the RNA and protein levels. Immunoprecipitation revealed the binding capabilities of both proteins, and detection of ScCst6 phosphorylation by ScSch9 in vitro confirmed Sch9 as the Cst6 kinase. We could show that CO2-dependent activation of Sch9, which is part of a kinase cascade, is mediated by lipid/Pkh1/2 signaling but not TORC1. Finally, we tested conservation of the identified regulatory cascade in the pathogenic yeast species C. albicans and C. glabrata. Deletion of SCH9 homologues of both species impaired CO2-dependent regulation of NCE103 expression, which indicates a conservation of the CO2 adaptation mechanism among yeasts. Thus, Sch9 is a Cst6/Rca1 kinase that links CO2 adaptation to lipid signaling via Pkh1/2 in fungi

Functional Interaction between Type III-Secreted Protein IncA of Chlamydophila psittaci and Human G3BP1

Chlamydophila (Cp.) psittaci, the causative agent of psittacosis in birds and humans, is the most important zoonotic pathogen of the family Chlamydiaceae. These obligate intracellular bacteria are distinguished by a unique biphasic developmental cycle, which includes proliferation in a membrane-bound compartment termed inclusion. All Chlamydiaceae spp. possess a coding capacity for core components of a Type III secretion apparatus, which mediates specific delivery of anti-host effector proteins either into the chlamydial inclusion membrane or into the cytoplasm of target eukaryotic cells. Here we describe the interaction between Type III-secreted protein IncA of Cp. psittaci and host protein G3BP1 in a yeast two-hybrid system. In GST-pull down and co-immunoprecipitation experiments both in vitro and in vivo interaction between full-length IncA and G3BP1 were shown. Using fluorescence microscopy, the localization of G3BP1 near the inclusion membrane of Cp. psittaci-infected Hep-2 cells was demonstrated. Notably, infection of Hep-2 cells with Cp. psittaci and overexpression of IncA in HEK293 cells led to a decrease in c-Myc protein concentration. This effect could be ascribed to the interaction between IncA and G3BP1 since overexpression of an IncA mutant construct disabled to interact with G3BP1 failed to reduce c-Myc concentration. We hypothesize that lowering the host cell c-Myc protein concentration may be part of a strategy employed by Cp. psittaci to avoid apoptosis and scale down host cell proliferation

Remote functionalization in surface-assisted dehalogenation by conformational mechanics: organometallic self-assembly of 3,3′,5,5′-tetrabromo-2,2′,4,4′,6,6′-hexafluorobiphenyl on Ag(111)

Even though the surface-assisted dehalogenative coupling constitutes the most abundant protocol in on-surface synthesis, its full potential will only become visible if selectivity issues with polybrominated precursors are comprehensively understood, opening new venues for both organometallic self-assembly and on-surface polymerization. Using the 3,3′,5,5′-tetrabromo-2,2′,4,4′,6,6′-hexafluorobiphenyl (Br4F6BP) at Ag(111), we demonstrate a remote site-selective functionalization at room temperature and a marked temperature difference in double- vs. quadruple activation, both phenomena caused by conformational mechanical effects of the precursor-surface ensemble. The submolecularly resolved structural characterization was achieved by Scanning Tunneling Microscopy, the chemical state was quantitatively assessed by X-ray Photoelectron Spectroscopy, and the analysis of the experimental signatures was supported through first-principles Density-Functional Theory calculations. The non-planarity of the various structures at the surface was specifically probed by additional Near Edge X-ray Absorption Fine Structure experiments. Upon progressive heating, Br4F6BP on Ag(111) shows the following unprecedented phenomena: (1) formation of regular organometallic 1D chains via remote site-selective 3,5′-didebromination; (2) a marked temperature difference in double- vs. quadruple activation; (3) an organometallic self-assembly based on reversibility of C–Ag–C linkages with a thus far unknown polymorphism affording both hexagonal and rectangular 2D networks; (4) extraordinary thermal stability of the organometallic networks. Controlled covalent coupling at the previously Br-functionalized sites was not achieved for the Br4F6BP precursor, in contrast to the comparatively studied non-fluorinated analogue

The Nachtlichter app: a citizen science tool for documenting outdoor light sources in public space

The relationship between satellite based measurements of city radiance at night and the numbers and types of physical lights installed on the ground is not well understood. Here we present the "Nachtlichter app", which was developed to enable citizen scientists to classify and count light sources along street segments over large spatial scales. The project and app were co-designed: citizen scientists played key roles in the app development, testing, and recruitment, as well as in analysis of the data. In addition to describing the app itself and the data format, we provide a general overview of the project, including training materials, data cleaning, and the result of some basic data consistency checks

Thermohydraulischer Lineargenerator – Basis für einen dieselelektrohydraulischen Hybrid

Auf dem Gebiet der mobilen Arbeitsmaschinen und Nutzfahrzeuge zeigen aktuelle Arbeiten weltweit ein verstärktes Interesse an leistungsverzweigten Antriebskonzepten auf Basis elektrischer und hydraulischer Hybridlösungen. Die Kombination beider Technologien verspricht wartungsarme, energieeffiziente Antriebssyteme mit hoher Steuer- und Regelbarbeit sowie hoher Kraftdichte. Die primär erzeugte mechanische Antriebsleistung der Wärmekraftmaschine kann meist für die Arbeitsprozesse und zur Versorgung zugehöriger Hilfsfunktionen nicht direkt verwendet werden. Diese muss je nach Anforderungen gewandelt bzw. angepasst oder bedarfsgerecht mittels zusätzlichen, wiederaufladbaren Speichern bereitgestellt werden. Solche hybriden Lösungsansätze führen jedoch gegenüber konventionellen Antrieben zu einer steigenden Komplexität sowie einem erhöhten technischen Aufwand. Nach dem Stand der Technik erfolgt die Erzeugung hydraulischer und elektrischer Leistung mit Hilfe mindestens dreier Komponenten: Verbrennungsmotor, Hydraulikpumpe und Generator. Für künftige antriebstechnische Innovationen ist daher aus funktionellen und energetischen Gründen ein einfaches, preiswertes Primäraggregat zur gleichzeitigen, bedarfsgerechten Bereitstellung hydraulischer und elektrischer Leistung wünschenswert, welches unnötige Umwandlungsverluste vermeidet und zusätzlich Kosten spart. Das Forschungsprojekt „Theoretische Grundlagen zur Verknüpfung von thermohydraulischer und thermoelektrischer Leistungswandlung in einem Aggregat – Thermohydraulischer Lineargenerator“ befasst sich mit einer belastbaren Abschätzung der technischen Realisierbarkeit und des technischen Aufwands eines derartigen neuen Antriebskonzeptes mit frei wählbarer Bereitstellung hydraulischer und elektrischer Leistung auf Basis des Freikolbenprinzips. Die grundlegenden Untersuchungen widmen sich der Kopplung zweier unterschiedlicher Leistungswandlungen, einer stabilen Prozessführung sowie der Analyse und Bewertung der physikalischen Prozessgrößen in Bezug auf eine zukünftige Auslegung eines Prototyps. Der Beitrag erklärt das Grundkonzept, zeigt den aktuellen Stand des Projekts auf und stellt die zum gegenwärtigen Zeitpunkt vorliegenden Ergebnisse vor