31325 research outputs found
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What’s ahead: navigating the future of environmental science in and around cities in post-pandemic times
No full textPeer Reviewe
Facile Spray-Coating of Antimicrobial Silica Nanoparticles for High-Touch Surface Protection
No full textThe rising threat from infectious pathogens poses an ever-growing challenge. Metal-based nanomaterials have gained a great deal of attention as active components in antimicrobial coatings. Here, we report on the development of readily deployable, sprayable antimicrobial surface coatings for high-touch stainless steel surfaces that are ubiquitous in many healthcare facilities to combat the spread of pathogens. We synthesized mesoporous silica nanoparticles (MSNs) with different surface functional groups, namely, amine (MSN-NH2), carboxy (MSN-COOH), and thiol groups (MSN-SH). These were chosen specifically due to their high affinity to copper and silver ions, which were used as antimicrobial payloads and could be incorporated into the mesoporous structure through favorable host–guest interactions, allowing us to find the most favorable combinations to achieve antimicrobial efficacy against various microbes on dry or semidry high-touch surfaces. The antimicrobial MSNs were firmly immobilized on stainless steel through a simple two-step spray-coating process. First, the stainless steel surfaces are primed with sprayable polyelectrolyte solutions acting as adhesion layers, and then, the loaded nanoparticle dispersions are spray-coated on top. The employed polyelectrolytes were selected and functionalized specifically to adhere well to stainless steel substrates while at the same time being complementary to the MSN surface groups to enhance the adhesion, wettability, homogeneity, and stability of the coatings. The antimicrobial properties of the nanoparticle suspension and the coatings were tested against three commonly found pathogenic bacteria, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, as well as a fungal pathogen, Candida albicans. Especially MSN-SH loaded with silver ions showed excellent antimicrobial efficacy against all tested pathogens under application-relevant, (semi)dry conditions. The findings obtained here facilitate our understanding of the correlation between the surface properties, payloads, and antimicrobial activity and show a new pathway toward simple and easily deployable solutions to combat the spread of pathogens with the help of sprayable antimicrobial surface coatings.HORIZON EUROPE Digital, Industry and Space 10.13039/100018699Staatssekretariat f?r Bildung, Forschung und Innovation 10.13039/501100007352Peer Reviewe
Nothing to claim: claim reports and non-endorsement
No full textWhile there has been much research on the typology of speech reports, the variety of communicative predicates has remained largely understudied. In line with the growing body of work on the fine-grained semantics of clause-taking predicates, we explore possible distinctions within the communicative group by zooming in on the behavior of the English verb claim. Our main focus is what we call the NON-ENDORSEMENT PUZZLE: a distinct sense that the speaker is not fully on board with the content of a claim report. We ruminate on possible sources of this effect, such as the speaker’s doxastic state or insufficient evidence, and conclude that non-endorsement is not conventionally encoded, but arises due to the properties of discourses described by claim. We argue that it reports assertions that have not been accepted (yet) and that the gap between the proposal and its possible acceptance is responsible for the sense that claim reports something less than an ideal Gricean assertion
Fading Shooting Stars—The Relative Age Effect, Ability, and Foregone Market Values in German Elite Youth Soccer
No full textThis article analyzes the relative age effect (RAE) in German elite youth soccer. We hypothesize that, to get selected by elite youth academies, players with relative age disadvantages must be relatively more talented; especially at the margin of getting selected. Using data on 2,383 former elite youth players and their later market values, we show that the RAE was substantial in German elite youth soccer between 2000 and 2020. Moreover, in the sample of former elite youth academy players, those with relative age disadvantages reach significantly higher market values. Our results indicate that relative age disadvantages of elite academy players are positively correlated with their unobserved ability; suggesting that, on average, the RAE results in a loss of talent—and market value. We find that clubs could generate 30.6 to 72.8% higher market values without the RAE.Peer Reviewe
The role of the GTGT motif in fly Polycomb and Trithorax response elements and their long non-coding RNAs
No full textDas Polycomb und Trithorax-System hält Genexpressionszustände durch epigeneti-sches Gedächtnis aufrecht. Die Proteine der Polycomb (PcG) und Trithorax-Gruppe (TrxG) wirken antagonistisch über Polycomb und Trithorax Response Elemente (PRE/TREs), bei denen es sich um bistabile, umschaltbare Elemente handelt, die sowohl stille als auch aktive Genexpressionszustände aufrechterhalten können. Bei Fliegen be-stehen PRE/TREs aus mehreren spezifischen Sequenzmotiven, die die Erkennung und direkte Bindung durch DNA-bindende Proteine ermöglichen, welche PcG- oder TrxG-Proteine rekrutieren. Eines dieser Motive ist das GTGT-Motiv, das in Fliegen PRE/TREs angereichert ist und von dem Zinkfingerprotein Combgap (Cg) gebunden wird. Das ves-tigial (vg) PRE/TRE wird bidirektional in vorwärts- und rückwärtsgerichtete lange nicht-kodierende RNAs (lncRNAs) transkribiert und enthält Cluster von GTGT Motiven. Diese Arbeit untersucht, wie GTGT Motive, Cg und lncRNAs am vg PRE/TRE in Drosophila zu-sammenwirken, mithilfe molekularbiologischer Techniken und in vivo Assays. Eine Überexpression der lncRNAs zeigte, dass die korrekte Strangexpression und -dosierung entscheidend für die Flügelentwicklung ist. Sequenzvergleiche mit Drosophila pseu-doobscura zeigten die evolutionäre Konservierung der GTGT Motive. Fliegen mit mutier-ten GTGT Motiven zeigten eine veränderte Expression der lncRNAs und eines Reporter-gens. RNAi von Cg in verschiedenen Geweben beeinträchtigte die Entwicklung der Flie-gen. Die Analyse des Transkriptoms nach ubiquitärer cg RNAi zeigte differenzielle Gen-expression und deutet auf eine regulatorische Rolle von Cg hin. Diese Daten stützen ein Modell, in dem Cg und GTGT Motive die Expression der lncRNAs durch Promotor-Pausierung regulieren, um eine dynamische Genexpression während der Entwicklung zu gewährleisten. Zusammenfassend zeigt diese Arbeit, wie GTGT Motive, Cg und lange nicht-kodierende RNAs am vg PRE/TRE zusammenwirken, um epigenetisches Gedächt-nis zu vermitteln.The Polycomb and Trithorax system maintains gene expression states via epigenetic memory. The Polycomb group (PcG) and Trithorax group (TrxG) proteins act antagonis-tically via Polycomb and Trithorax response elements (PRE/TREs), which are bistable, switchable elements that can maintain both silent and active gene expression states. In flies, PRE/TREs consist of multiple specific sequence motifs, which enable the recogni-tion by and direct binding of DNA binding proteins that recruit PcG or TrxG proteins. One such motif is the GTGT repeat, enriched in fly PRE/TREs and bound by the zinc fin-ger protein Combgap (Cg). The fly PRE/TRE vestigial (vg) is bidirectionally transcribed into forward and reverse long non-coding RNAs and contains clusters of GTGT motifs. This thesis explores how GTGT motifs, Cg, and long non-coding RNAs cooperate at the vg PRE/TRE in Drosophila melanogaster using molecular techniques and in vivo assays. Overexpression of the vg long non-coding RNAs revealed that correct strand expression and dosage are crucial for proper wing development. Sequence comparisons with Dro-sophila pseudoobscura show evolutionary conservation of GTGT motifs, highlighting their functional importance. Transgenic flies with mutated GTGT motifs showed altered lncRNA and reporter gene expression, confirming their role. Tissue-specific cg RNAi knockdowns impaired development and vg lncRNA expression. Transcriptome analysis after ubiquitous cg RNAi revealed differential gene expression, indicating a broader regu-latory role of Cg. The data support a model where Cg and GTGT motifs regulate vg lncRNA expression through promoter pausing, ensuring dynamic gene regulation during development. In summary, this work shows how GTGT motifs, Cg, and long non-coding RNAs collaborate at the vg PRE/TRE to mediate epigenetic memory and gene expression
Biofilm-relevant genes in Escherichia coli and their control by intra- and extracellular signals
No full textDie Biofilmbildung von E. coli K-12 Makrokolonien wird durch eine komplexe Signalkaskade gesteuert, die den Wechsel von einer planktonischen, motilen und wachstums-orientierten hin zu einer mulitzellulären Lebensweise reguliert. Der sekundäre Botenstoff c-di-GMP spielt bei diesem Prozess eine Schlüsselrolle, indem er die Expression des Masterregulators CsgD kontrolliert. Die Ergebnisse dieser Arbeit führten zu einem besseren Verständnis der Signaltransduktion des RdcA-RdcB-DgcE-Komplexes. Der Sensor RdcA-RdcB nimmt das Gleichgewicht zwischen GTP und (p)ppGpp wahr, was eine präzise und schnelle Anpassung an Veränderungen ihrer Konzentrationen ermöglicht. Damit misst und kontrolliert das Sensor-Transduktionssystem ein komplexes Zusammenspiel der drei Nukleotide GTP, (p)ppGpp und c-di-GMP zur Regulation der ECM-Synthese in Makrokolonien. Darüber hinaus ermöglicht diese Arbeit Einblicke in die Biofilm-hemmende Wirkung von extrazellulären Signalen Kretischer Pflanzen. Während die Hauptstrategie darin zu bestehen scheint, die Polymerisation von Curli-Fasern zu verhindern, hemmen einige Pflanzen auch die Synthese der Matrix durch eine Störung das Gleichgewicht zwischen Wachstum/Proliferation und Überleben/Stressreaktion auf Transkriptionsebene. Des Weiteren zeigte diese Arbeit, dass c-di-GMP ein wirksamer globaler Regulator ist, der die Genexpression vieler stress- und metabolischer Gene moduliert. C-di-GMP hat einen Effekt auf die generelle Stressantwort durch differenzielle Regulierung einiger RpoS-abhängiger Gene. Eine Kombination aus spezifischen und globalen c-di-GMP-Effekten auf der Ebene der Transkription, des mRNA-Umsatzes und der Proteinacetylierung vermittelt dies. Insgesamt deuten die Ergebnisse darauf hin, dass sehr hohe globale c-di-GMP-Spiegel zu einer präzisen Anpassung der allgemeinen Stressantwort in Zellen der stationären Phase in der oberen Biofilmschicht führen, welche aufgrund ihrer Position in der exponiertesten Schicht des Biofilms erforderlich ist.The macrocolony biofilm formation of E. coli K-12 is controlled by a complex network that regulates the switch from a planktonic and flagellated, growth-orientated to a multicellular lifestyle characterized by increased stress resistance and survival strategies. The second messenger c-di-GMP plays a key role in this process by controlling the expression of the master regulator CsgD. The results of this work led to a better understanding of the signaling mechanism of the RdcA-RdcB-DgcE complex. RdcA-RdcB senses the balance between GTP and (p)ppGpp which enables precise and fast adaptation to small changes in their concentrations. With this, the sensor-transduction system senses and/or controls a complex interplay of the three guanosine-based nucleotides GTP, (p)ppGpp, and c-di-GMP to regulate the ECM synthesis of a macrocolony. In addition, this work allows further insights into the anti-biofilm activity of extracellular stimuli by Cretan plants. While the major strategy seems to be preventing the polymerization of curli fibers, some plants also inhibit the synthesis of the matrix by modulating the master regulator CsgD caused by a disturbance of the growth/proliferation vs. survival/stress response balance. Furthermore, this work revealed that c-di-GMP is a potent global regulator that modulates gene expression and many stress-related and metabolic genes. C-di-GMP modulates the stationary phase response by differentially regulating a subset of RpoS-dependent genes. A combination of specific and global c-di-GMP effects on the level of transcription, mRNA turnover and protein acetylation mediate this regulation. Overall, the findings indicate that very high global c-di-GMP levels - found only in biofilms but not in liquid cultures of E. coli K-12 - result in a precise adjustment of the general stress response in stationary phase cells of the upper biofilm layer needed due to their position in the most exposed layer of the biofilm
Abundance and Diversity of Meiofaunal Organisms at Different Habitats of the Wadden Sea (Sylt)
No full textMeiofaunal organisms play a crucial role in marine ecosystems of the Wadden Sea. These organisms are good indicators of environmental disturbances in the various habitats they occupy, such as sand flats, harbours, mudflats, or oyster beds. These different habitats contain different grain sizes, which influence the oxygenation of the sediments. Therefore we investigated the diversity and abundance of meiofaunal organisms in these different locations. The study involved soil sampling from these areas, using an Uhlig-Apparatus to extract the organisms followed by counting and identifying them under a dissecting microscope. We limited our focus to identifying phyla, successfully identifying eleven distinct ones. The mudflats showed the lowest diversity and abundance due the challenging environmental conditions. Sand flats, oyster beds and harbour displayed a higher abundance and diversity providing better conditions for meiofaunal communities.Peer Reviewe
Electrical Conductivity as a Tracer for Seasonal Reverse Flow and Transport of Trace Organic Contaminants in River Spree
No full textClimate change, population growth, urbanisation and water pollution will exacerbate the closely linked challenges of water quantity and water quality. The River Spree in Berlin, Germany, experiences recurrent low flow conditions in summer with seasonal flow reversals in certain sections of the river. This reverse flow leads to the transport of treated wastewater to upstream sections of River Spree and possibly to the introduction of treated wastewater into Lake Müggelsee, which is located upstream of the city centre and important for drinking water production via bank filtration in Berlin. A better understanding of the flow and contaminant dynamics in River Spree is required, but field data on the reverse flow are still lacking. In 2022 and 2023, we collected surface water samples to quantify major ions and trace organic contaminants. Over a period of nine months in 2023, we also measured the specific electrical conductivity at six locations with a temporal resolution of five minutes. During summer, the specific electrical conductivity increased at the sampling locations in River Spree upstream of the mouth of the wastewater‐impaired River Erpe. The specific electrical conductivity proved to be an indicative parameter for the seasonal dynamics of reverse flow periods. During reverse flow, we observed increased concentrations of wastewater‐derived trace organic contaminants, many of which correlated positively with the specific electrical conductivity. Strong differences in the reverse flow intensity between 2022 and 2023 indicate that both precipitation and discharge of the River Spree upstream of Lake Müggelsee have a strong influence on the reverse flow. This study demonstrates the applicability of easy‐to‐measure specific electrical conductivity as a proxy for hydrological conditions and chemical water quality.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347Peer Reviewe
Vierundzwanzigste Änderung der Fächerübergreifenden Satzung zur Regelung von Zulassung, Studium und Prüfung der Humboldt- Universität zu Berlin (ZSP-HU)
No full textMeasurement of the Atmospheric High-Energy Muon Flux with IceCube
No full textDiese Arbeit stellt ein Update zur Suche nach hochenergetischen Myonen dar, die unser Verständnis der Erzeugung prompter Myonen in atmosphärischen Luftschauern verbessern soll. Der Myonenfluss innerhalb des IceCube-Detektors wird bestimmt, indem Ereignisse identifiziert werden, bei denen das Myonenbündel eine große Energieverlustkaskade enthält, um so Bündel zu selektieren, die von einem einzelnen hochenergetischen Myon dominiert werden. Die Analyse wird auf den IceCube-Daten aufgenommen von 2012 bis 2014 durchgeführt. Der zentrale Analyse-Parameter ist die Normalisierung der Prompt-Komponente des atmosphärischen Myonenflusses relativ zum sog. ERS-Modell, welches eine Vorhersage für den Beitrag von Leptonen aus dem Zerfall von Mesonen mit Charm-Komponente macht. Ein zusätzlicher Beitrag stammt aus den Zerfällen von leichten, flavor-freien Mesonen, der bis zu einer Energie von 10 PeV die nahezu gleiche Normalisierung und Form hat, wodurch die erwartete Prompt-Normalisierung etwa dem Doppelten des ERS-Modells entspricht. Das Ergebnis hängt stark vom angenommenen Modell für den Fluss kosmischer Primärstrahlung sowie dessen Massenkomposition ab. Inklusive systematischer Unsicherheiten fällt das Resultat in einen Bereich zwischen dem 2- und 6-fachen der ERS-Vorhersage, mit modellabhängigen Best-Fit-Werten von 2.7 und 4.2. Das Resultat stellt eine klare statistische Evidenz für die Existenz eines prompten Myonenflusses dar. Falls der Beitrag von flavor-freien Mesonen etwa der Vorhersage des ERS-Modells entspricht, deutet das Ergebnis eine Charm-Produktion am oberen Ende der theoretischen Vorhersage oder darüber hinaus an. Während die genaue Prompt-Normalisierung von unserem Verständnis des Flusses der kosmischen Primärstrahlung abhängt, bedeuten diese Ergebnisse eine starke Evidenz für einen signifikanten Fluss prompter Myonen und stärken die Hypothese, dass eine intrinsische Charm-Komponente existiert.This work presents an update on the search for high-energy muons in an effort to improve our understanding of prompt muon production in atmospheric air showers. The measurement represents a unique method to constrain the level of charm production in nuclear interactions independent of collider experiments. The muon flux inside the IceCube detector is estimated by identifying events where the muon bundle from the air shower contains a large stochastic energy loss in order to identify bundles dominated by an individual high-energy muon. The analysis is performed on three years of IceCube data recorded from 2012 to 2014. The main analysis parameter is the normalization of the prompt component in the atmospheric muon flux relative to the ERS model which provides an estimate of the contribution of leptons from charmed mesons. An additional contribution comes from the decay of light unflavored mesons which is almost identical in normalization and shape up to a muon energy of 10 PeV, resulting in an expected prompt muon normalization of approximately twice the prediction of the ERS model. The result of the analysis depends strongly on the assumed primary cosmic ray flux and its composition in the relevant energy range. Including systematics, the result falls in a range between about 2 and 6 ERS, with model-dependent best-fit values of 2.7 and 4.2. The result shows clear statistical evidence for the existence of an atmospheric prompt muon flux. If the contribution of unflavored mesons corresponds to roughly the equivalent of the prediction of the ERS model, the result indicates that charm production is at the high end of the theoretical prediction or above. While the exact prompt normalization depends on our understanding of the primary cosmic ray flux, these results provide strong evidence for a significant prompt muon flux and strengthen the hypothesis that an intrinsic charm component exists