Entwicklung funktioneller Nanofasersysteme: Einsatz im Pflanzenschutz und in der Oberflächenmodifizierung

Diese Arbeit beschäftigt sich mit der Entwicklung funktioneller Materialsysteme auf Basis von Nanofasern für neuartige Anwendungen. Der Fokus lag dabei auf zwei unterschiedlichen Applikationen. Ein Ziel dieser Arbeit war die Entwicklung eines Trägers aus Polymernanofasern für flüchtige Signalstoffe (Pheromone) zur biotechnischen Regulierung von Schadinsekten im ökologischen und integrierten Landbau. Das zweite Ziel bestand darin, die Eigenschaften von Oberflächen durch eine kontrollierte und präzise Abscheidung von Nano- und Mikrofasern zu modifizieren und zu funktionalisieren. Die Nanofaserherstellung erfolgte in beiden Fällen über die Methode des Elektrospinnens. Für eine kontrollierte und präzise Ablage von Nano und Mikrofasern auf Oberflächen wurde auf eine Variante des Elektrospinnens, auf das Präzisionselektrospinnen, zurückgegriffen

Ansatzpunkte zur Veränderung sozialer Praktiken in Unternehmen durch Managementberater: Eine empirische Analyse

Diese Arbeit untersucht mit Hilfe von vier Fallbeispielen, wie Managementberater Unternehmen verändern können. Den theoretischen Hintergrund der Arbeit bildet der Practice Turn in der Sozialtheorie bzw. der Strategy-As-Practice Ansatz in der Managementwissenschaft. Vor diesem werden sowohl Unternehmen als auch die Arbeit von Managementberatern theoretisch neu beschrieben. Es wird gezeigt, wie Managementberater ein aufgeklärt rationales Problem- und Lösungsverständnis entwickeln, um eine koordinierte Veränderung der sozialen Praktiken in Unternehmen zu bewirken. Durch die Nutzung von Artefakten kann die Veränderung zusätzlich abgesichert werden. Die Ergebnisse der Arbeit werden in einem konzeptionellen Rahmen zusammengefasst, auf dessen Basis auch konkrete Gestaltungsempfehlungen gegeben werden. --Soziale Praktik,Praxistheorie,practice theory,strategy as practice,Managementberatung,Unternehmensberatung,consulting,Bourdieu,Giddens,Schatzki,Latour,Fallstudie,case study,Reflexivität,reflexivity

A systematic evaluation of single cell RNA-seq analysis pipelines

The recent rapid spread of single cell RNA sequencing (scRNA-seq) methods has created a large variety of experimental and computational pipelines for which best practices have not yet been established. Here, we use simulations based on five scRNA-seq library protocols in combination with nine realistic differential expression (DE) setups to systematically evaluate three mapping, four imputation, seven normalisation and four differential expression testing approaches resulting in similar to 3000 pipelines, allowing us to also assess interactions among pipeline steps. We find that choices of normalisation and library preparation protocols have the biggest impact on scRNA-seq analyses. Specifically, we find that library preparation determines the ability to detect symmetric expression differences, while normalisation dominates pipeline performance in asymmetric DE-setups. Finally, we illustrate the importance of informed choices by showing that a good scRNA-seq pipeline can have the same impact on detecting a biological signal as quadrupling the sample size

The impact of amplification on differential expression analyses by RNA-seq

Currently, quantitative RNA-seq methods are pushed to work with increasingly small starting amounts of RNA that require amplification. However, it is unclear how much noise or bias amplification introduces and how this affects precision and accuracy of RNA quantification. To assess the effects of amplification, reads that originated from the same RNA molecule (PCR-duplicates) need to be identified. Computationally, read duplicates are defined by their mapping position, which does not distinguish PCR-from natural duplicates and hence it is unclear how to treat duplicated reads. Here, we generate and analyse RNA-seq data sets prepared using three different protocols (Smart-Seq, TruSeq and UMI-seq). We find that a large fraction of computationally identified read duplicates are not PCR duplicates and can be explained by sampling and fragmentation bias. Consequently, the computational removal of duplicates does improve neither accuracy nor precision and can actually worsen the power and the False Discovery Rate (FDR) for differential gene expression. Even when duplicates are experimentally identified by unique molecular identifiers (UMIs), power and FDR are only mildly improved. However, the pooling of samples as made possible by the early barcoding of the UMI-protocol leads to an appreciable increase in the power to detect differentially expressed genes

Extrapolation and Prediction of User Behaviour from Wireless Home Automation Communication

Wireless home automation systems are becoming increasingly popular. They can help users save energy and increase the comfort.However, this increased convenience also comes with new attack vectors. Many available systems provide little to no security. In this paper, we explore the possibilities of passive attacks against these systems. We exemplarily investigate two real-world installations of off-the-shelf home automation systems to see what amount of information can be obtained by a passive adversary.Our results show that the systems provide no privacy. They leak information about the users' habits as well as their presence and can be abused to plan burglaries. Furthermore, we conclude that even encrypted communication does not fully protect against the attack presented here. In particular, it is still possible to predict user presence and absence even if individual actions cannot be identified

zUMIs - A fast and flexible pipeline to process RNA sequencing data with UMIs

Background: Single-cell RNA-sequencing (scRNA-seq) experiments typically analyze hundreds or thousands of cells after amplification of the cDNA. The high throughput is made possible by the early introduction of sample-specific bar codes (BCs), and the amplification bias is alleviated by unique molecular identifiers (UMIs). Thus, the ideal analysis pipeline for scRNA-seq data needs to efficiently tabulate reads according to both BC and UMI. Findings: zUMIs is a pipeline that can handle both known and random BCs and also efficiently collapse UMIs, either just for exon mapping reads or for both exon and intron mapping reads. If BC annotation is missing, zUMIs can accurately detect intact cells from the distribution of sequencing reads. Another unique feature of zUMIs is the adaptive downsampling function that facilitates dealing with hugely varying library sizes but also allows the user to evaluate whether the library has been sequenced to saturation. To illustrate the utility of zUMIs, we analyzed a single-nucleus RNA-seq dataset and show that more than 35% of all reads map to introns. Also, we show that these intronic reads are informative about expression levels, significantly increasing the number of detected genes and improving the cluster resolution. Conclusions: zUMIs flexibility makes if possible to accommodate data generated with any of the major scRNA-seq protocols that use BCs and UMIs and is the most feature-rich, fast, and user-friendly pipeline to process such scRNA-seq data

Origin of isotopic diversity among carbonaceous chondrites

Carbonaceous chondrites are some of the most primitive meteorites and derive from planetesimals that formed a few million years after the beginning of the solar system. Here, using new and previously published Cr, Ti, and Te isotopic data, we show that carbonaceous chondrites exhibit correlated isotopic variations that can be accounted for by mixing among three major constituents having distinct isotopic compositions, namely refractory inclusions, chondrules, and CI chondrite-like matrix. The abundances of refractory inclusions and chondrules are coupled and systematically decrease with increasing amount of matrix. We propose that these correlated abundance variations reflect trapping of chondrule precursors, including refractory inclusions, in a pressure maximum in the disk, which is likely related to the water ice line and the ultimate formation location of Jupiter. The variable abundance of refractory inclusions/chondrules relative to matrix is the result of their distinct aerodynamical properties resulting in differential delivery rates and their preferential incorporation into chondrite parent bodies during the streaming instability, consistent with the early formation of matrix-poor and the later accretion of matrix-rich carbonaceous chondrites. Our results suggest that chondrules formed locally from isotopically heterogeneous dust aggregates which themselves derive from a wide area of the disk, implying that dust enrichment in a pressure trap was an important step to facilitate the accretion of carbonaceous chondrite parent bodies or, more generally, planetesimals in the outer solar system.Comment: 12 pages, 4 figures, 1 table. Accepted for publication in ApJ

Elektrogesponnene Nanofaser-Pheromon-Dispenser zur Regulierung des Bekreuzten Traubenwicklers (Lobesia botrana (Denis & Schiffermuller 1775))

Elektrogesponnene, organische Nanofasern sind neuartige Träger für flüchtige Signalstoffe zur biotechnischen Regulierung von Schadinsekten im integrierten und ökologischen Landbau. Der Einsatz von Pheromonen im Pflanzenschutz ist als eine umweltverträgliche Alternative zur Verwendung von chemisch-synthetischen Insektiziden oder als dessen Ergänzung bekannt. Die pheromonbeladenen Nanofasern wirken als Dispenser und sollten vom Konzept her eine möglichst kontinuierliche, räumlich und zeitlich gleichmäßige Abgaberate der flüchtigen Signalstoffe ermöglichen. Anforderungen sind, dass die Fasern wetterstabil sind, lang anhaltend funktionieren, einfach und kostengünstig ausgebracht sowie rückstandsfrei abgebaut werden können. Es werden Ergebnisse von Halb-Freilandversuchen präsentiert, die den Nachweis der prinzipiellen Funktionsfähigkeit von pheromonbeladenen, elektrogesponnenen Polymerfaserdispensern zur Insektenverwirrung erbringen. Der in unseren Versuchen eingesetzte Bekreuzte Traubenwickler, Lobesia botrana, dient uns lediglich als Modellorganismus. Eine Ausweitung dieser Technik auf andere Schadorganismen ist geplant

Sensitive and powerful single-cell RNA sequencing using mcSCRB-seq

Single-cell RNA sequencing (scRNA-seq) has emerged as a central genome-wide method to characterize cellular identities and processes. Consequently, improving its sensitivity, flexibility, and cost-efficiency can advance many research questions. Among the flexible platebased methods, single-cell RNA barcoding and sequencing (SCRB-seq) is highly sensitive and efficient. Here, we systematically evaluate experimental conditions of this protocol and find that adding polyethylene glycol considerably increases sensitivity by enhancing cDNA synthesis. Furthermore, using Terra polymerase increases efficiency due to a more even cDNA amplification that requires less sequencing of libraries. We combined these and other improvements to develop a scRNA-seq library protocol we call molecular crowding SCRB-seq (mcSCRB-seq), which we show to be one of the most sensitive, efficient, and flexible scRNA-seq methods to date