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The actomyosin system generates mechanical work with the execution of the power stroke, an ATP-driven, two-step rotational swing of the myosin-neck that occurs post ATP hydrolysis during the transition from weakly to strongly actin-bound myosin states concomitant with Pi release and prior to ADP dissociation. The activating role of actin on product release and force generation is well documented; however, the communication paths associated with weak-to-strong transitions are poorly characterized. With the aid of mutant analyses based on kinetic investigations and simulations, we identified the W-helix as an important hub coupling the structural changes of switch elements during ATP hydrolysis to temporally controlled interactions with actin that are passed to the central transducer and converter. Disturbing the W-helix/transducer pathway increased actin-activated ATP turnover and reduced motor performance as a consequence of prolonged duration of the strongly actin-attached states. Actin-triggered Pi release was accelerated, while ADP release considerably decelerated, both limiting maximum ATPase, thus transforming myosin-2 into a high-duty-ratio motor. This kinetic signature of the mutant allowed us to define the fractional occupancies of intermediate states during the ATPase cycle providing evidence that myosin populates a cleft-closure state of strong actin interaction during the weak-to-strong transition with bound hydrolysis products before accomplishing the power stroke.
Current knowledge about cell-biomaterial interactions is often based on 2D cell culture systems like protein-coated glass slides. However, such smooth surfaces cannot mimic the nanofibrous environment of the native extracellular matrix (ECM). It is therefore a major challenge to transfer the results from 2D surfaces to 3D protein scaffolds with biomimetic nanofiber architecture. To understand the influence of different protein topographies on the cell response we introduce a new process to fabricate binary collagen scaffolds of variable thickness with spatially controlled regions of nanofibrous and smooth topography. We used pH-induced self-assembly to prepare collagen nanofibers with diameters between 130 and 150 nm on glass surfaces, which were partly covered with a polymer mask. After cross-linking with glutaraldehyde, smooth collagen films were prepared on the remaining glass regions. Atomic force microscopy revealed a much lower surface roughness of smooth collagen compared to nanofibers.
Data emerged as a central success factor for companies to benefit from digitization. However, the skills in successfully creating value from data – especially at the management level – are not always profound. To address this problem, several canvas models have already been designed. Canvas models are usually created to write down an idea in a structured way to promote transparency and traceability. However, some existing data science canvas models mainly address developers and are thus unsuitable for decision-makers and communication within interdisciplinary teams. Based on a literature review, we identified influencing factors that are essential for the success of data science projects. With the information gained, the Data Science Canvas was developed in an expert workshop and finally evaluated by practitioners to find out whether such an instrument could support data-driven value creation.
Representation and Experience-Based Learning of Explainable Models for Robot Action Execution
(2021)
For robots acting in human-centered environments, the ability to improve based on experience is essential for reliable and adaptive operation; however, particularly in the context of robot failure analysis, experience-based improvement is only useful if robots are also able to reason about and explain the decisions they make during execution. In this paper, we describe and analyse a representation of execution-specific knowledge that combines (i) a relational model in the form of qualitative attributes that describe the conditions under which actions can be executed successfully and (ii) a continuous model in the form of a Gaussian process that can be used for generating parameters for action execution, but also for evaluating the expected execution success given a particular action parameterisation. The proposed representation is based on prior, modelled knowledge about actions and is combined with a learning process that is supervised by a teacher. We analyse the benefits of this representation in the context of two actions – grasping handles and pulling an object on a table – such that the experiments demonstrate that the joint relational-continuous model allows a robot to improve its execution based on experience, while reducing the severity of failures experienced during execution.
Nudging stellt eine Methode zur positiven Verhaltensbeeinflussung unserer Mitmenschen dar. Mit diesem Instrument kann das Sicherheits- und Gesundheitsverhalten von Arbeitnehmern gestärkt werden. Allerdings findet sie trotz intensiver Forschung bislang wenig Anwendung im betrieblichen Kontext. Daher lautet die Forschungsfrage dieser Arbeit: „Wie lässt sich Nudging seitens der Unternehmen als Präventionsmaßnahme während der Corona-Pandemie einsetzen?“. Mit der Übertragung von Nudging in der Arbeitswelt auf die derzeitigen Herausforderungen der aktuellen Corona-Pandemie leistet diese Arbeit einen wichtigen Beitrag zur Entwicklung neuer Präventionsmaßnahmen in Unternehmen. In der Arbeit konnte festgestellt werden, dass die Entwicklung von Nudges im Unternehmen unter Einbeziehung der Mitarbeiter in einem proaktiven und partizipativen Prozess stattfinden sollte. Mithilfe eines solchen Prozesses werden Gründe für das mögliche Fehlverhalten der Arbeitnehmer analysiert. Anschließend sollten Nudging-Techniken eingesetzt werden, die genau an diesen Punkten anknüpfen – am Fehlverhalten der Menschen. Über den partizipativen Nudging-Prozess wird die Akzeptanz der Arbeitnehmer im Hinblick auf etwaige Maßnahmen gefördert. Es wird am reflektierten Entscheidungssystem der Arbeitnehmer angesetzt. Unter Berücksichtigung der Corona-Pandemie sollte im betrieblichen Kontext zur Förderung des Sicherheitsverhaltens besonders auf den Wirkmechanismus „Norms“ gesetzt werden. Im Home-Office eignen sich aufgrund der Distanz zu den Arbeitnehmern Nudges mit technischer Natur, wie z.B. automatisierte Anmeldungen zu Maßnahmen des Gesundheitsmanagements. Hier greift der Wirkmechanismus „Defaults“. Diese Bachelorarbeit wurde als theoretische Arbeit auf Grundlage einer Literaturrecherche verfasst.
New sustainable, environmentally friendly materials for thermal insulation of buildings are necessary to reduce their carbon footprints. In this study, Miscanthus fiber-reinforced geopolymer composites, foamed with sodium dodecyl sulfate (SDS), were developed using fly ash as a geopolymer precursor. The effects of fiber content, fiber size, curing temperature, foaming agent content, fumed silica specific surface area and fumed silica content on thermal conductivity and compressive strength were evaluated using a Plackett-Burman design of experiment. Furthermore, the microstructure of geopolymer composites was investigated using X-ray diffraction (XRD), X-ray micro-computed tomography (μCT) and scanning electron microscopy (SEM). The measured characteristic values were in the following ranges: Thermal conductivity 0.057 W (m K)−1 to 0.127 W (m K)−1, compressive strength 0.007 MPa–0.719 MPa and porosity 49 vol% to 76 vol%. The results reveal an enhancement of thermal conductivity by elevated fiber size and foaming agent content. In contrast, the compressive strength is enhanced by high fiber content. Additionally, SEM images indicate a good interaction between the fibers and the geopolymer matrix, because nearly the whole fiber surface is covered by the geopolymer.
As a low-input crop, Miscanthus offers numerous advantages that, in addition to agricultural applications, permits its exploitation for energy, fuel, and material production. Depending on the Miscanthus genotype, season, and harvest time as well as plant component (leaf versus stem), correlations between structure and properties of the corresponding isolated lignins differ. Here, a comparative study is presented between lignins isolated from M. x giganteus, M. sinensis, M. robustus and M. nagara using a catalyst-free organosolv pulping process. The lignins from different plant constituents are also compared regarding their similarities and differences regarding monolignol ratio and important linkages. Results showed that the plant genotype has the weakest influence on monolignol content and interunit linkages. In contrast, structural differences are more significant among lignins of different harvest time and/or season. Analyses were performed using fast and simple methods such as nuclear magnetic resonance (NMR) spectroscopy. Data was assigned to four different linkages (A: β-O-4 linkage, B: phenylcoumaran, C: resinol, D: β-unsaturated ester). In conclusion, A content is particularly high in leaf-derived lignins at just under 70% and significantly lower in stem and mixture lignins at around 60% and almost 65%. The second most common linkage pattern is D in all isolated lignins, the proportion of which is also strongly dependent on the crop portion. Both stem and mixture lignins, have a relatively high share of approximately 20% or more (maximum is M. sinensis Sin2 with over 30%). In the leaf-derived lignins, the proportions are significantly lower on average. Stem samples should be chosen if the highest possible lignin content is desired, specifically from the M. x giganteus genotype, which revealed lignin contents up to 27%. Due to the better frost resistance and higher stem stability, M. nagara offers some advantages compared to M. x giganteus. Miscanthus crops are shown to be very attractive lignocellulose feedstock (LCF) for second generation biorefineries and lignin generation in Europe.
İnsanlar yeryüzünün doğal kaynaklarını onun bunları yenileyebileceğinden daha hızlı tüketmektedirler. İnsanların bu tutumlarının bedelini gelecek kuşaklar ödeyeceklerdir. Gelecek kuşaklara bu bedeli ödetmemek için artık parasal kârları ençoklamak, niceliksel olarak büyümek ve bolluk yaratmak doğrultusunda işleyen şimdiki ekonomik faaliyetleri bir başka biçime dönüştürmek kaçınılmazdır. Peren Teoremi göstermektedir ki Dünya örneğinde de olduğu gibi kapalı bir sistem doğal kaynak tüketimi eş düzeyde bir doğal kaynak üretimi ile yaşayabilir. Üretim ile tüketim arasındaki denge çok uzun bir süre bozulursa gezegen doğal bir ölüm ile karşılaşır. Bunu sağlamak üzere Dünya üzerinde yaşayan ve/veya dünya sayesinde yaşayan tüm insanların kişi başına doğal kaynak tüketimlerini artan küresel nüfusla orantılı bir biçimde azaltmak gerekir.
Die digitale Universität
(2021)
Die digitale Universität muss als eine Form des Erscheinens ihrer Mitglieder in spezifischen Räumen und Handlungen verstanden werden. Die Verhandlung ihrer Bedingungen ist von brennender Aktualität: Das Feuer, das die Idee der digitalen Universität entfacht, hat das Potential, die apriorische Ebene von Universität zu verabschieden und ihre neue Setzung zu veranlassen.
Die Transformationen der Wissenschaft, ihrer Systeme und Ordnungen fokussiert sich meist auf eine Politik des Digitalen beziehungsweise eine Politik der Digitalität. Durch die jüngsten Ereignisse, die auch die Universität in eine Krisen- und Ausnahmesituation bringen, gewinnt dieser Aspekt eine besondere Brisanz. Die unumgängliche Entwicklung neuer Lehr- und Forschungsformate führt zu einem grundlegenden Strukturwandel der Universität. Diese Frage von philosophischer oder universitätstheoretischer Brisanz, muss ein ernsthaftes Nachdenken über die Idee der digitalen Universität anstoßen. Digitalität und Universität können nicht länger als voneinander getrennte und unveränderliche Begriffe und Phänomene aufgefasst werden, denn sie sind in ihrer Kombination intrinsisch miteinander verbunden. (Verlagsangaben)
Kompetenzen auf dem Gebiet der Datenbanken gehören zum Pflichtbereich der Informatik. Das Angebot an Lehrbüchern, Vorlesungsformaten und Tools lässt sich jedoch für Lehrende oft nur eingeschränkt in die eigene Lehre integrieren. In diesem Aufsatz schildern wir unsere Erfahrungen in der Nutzung (frei) verfügbarer und der Entwicklung eigener digitaler Inhalte für grundlegende Datenbankveranstaltungen. Die Präferenzen der Studierenden werden mittels Nutzungsanalysen und Befragungen ermittelt. Wir stellen die Anforderungen auf, wie die nicht selten aufwendig herzustellenden digitalen Materialien von Lehrenden in ihre Lehr- und Lernumgebungen integriert werden können. Als konstruktive Antwort auf diese Herausforderung wird das Konzept EILD zur Entwicklung von Inhalten für die Lehre im Fach Datenbanken vorgestellt. Die Inhalte sollen in vielfältigen Lernszenarien eingesetzt werden können und mit einer Creative Commons (CC) Lizenzierung als OER (open educational resources) frei zur Verfügung stehen.
Alleine Bowling spielen?
(2021)
Womöglich ist das social distancing dieser Tage gar kein soziales sondern einfach nur ein körperliches, ein body distancing. Sozial können wir heute auch sein, ohne uns physisch zu begegnen. Wir können sogar "gemeinsam einsam" musizieren oder im Chor singen. Trotzdem geht etwas verloren - und am Ende wissen wir Zusammenkünfte in Vereinen welcher Art auch immer vielleicht wieder besonders zu schätzen.
Graph drawing with spring embedders employs a V ×V computation phase over the graph’s vertex set to compute repulsive forces. Here, the efficacy of forces diminishes with distance: a vertex can effectively only influence other vertices in a certain radius around its position. Therefore, the algorithm lends itself to an implementation using search data structures to reduce the runtime complexity. NVIDIA RT cores implement hierarchical tree traversal in hardware. We show how to map the problem of finding graph layouts with force-directed methods to a ray tracing problem that can subsequently be implemented with dedicated ray tracing hardware. With that, we observe speedups of 4× to 13× over a CUDA software implementation.
