Untersuchung des Brandverhaltens unterschiedlichen Mobiliars bei reproduzierbarem Entstehungsbrand. Teil 2

Im vorliegenden Bericht werden die im Vorgängerbericht dargestellten Überlegungen zur Reproduzierbarkeit von Brandversuchen erweitert. Auf Grundlage verbrennungstechnischer Theorien, welche zunächst auch vorgestellt werden, soll untersucht werden, ob sich klassische verbrennungstechnische Annahmen auf Realbrandszenarien übertragen lassen. Auf Grundlage geeigneter Vorversuche, welche aus dem Vorgängerbericht 203 abgeleitet und hochskaliert wurden, wird eine Materialauswahl mit entsprechender Probenverfügbarkeit getroffen. Besonders untersucht werden hierin folglich Möbel moderner Bauart. Damit sollen die in Forschungsbericht 203 angedeuteten potentiellen Unterschiede in der Brandentstehungsphase umrissen und mit abgedeckt werden. Folglich werden 3 Raumbrandversuche unter kontrollierten Bedingungen durchgeführt. Es wird bei Werkstoffauswahl, Ventilationsbedingungen, Initialbrandlast und Initialbrandart penibel darauf geachtet reproduzierbare Bedingungen herzustellen. Mit Hilfe aufwändiger Messtechnik wurden zudem Emissionsmessungen und Temperaturverteilungen – jeweils aufgelöst über der Raumhöhe – durchgeführt. Hierfür wurde eine höhenverstellbare Probenahmesonde konzipiert und konstruiert, mit deren Hilfe in verschiedenen Raumhöhen gemessen werden kann. Auf Grundlage dieser Versuchsreihe wird erörtert, inwiefern Großversuche dieser Art reproduzierbar durchführbar sind. Ergänzt wurden diese Messungen um Messungen der Konzentration von Cyanwasserstoff, welche in Kooperation mit der DEKRA Umwelt GmbH durchgeführt wurden

Exploring Consumers Risk Mitigation Strategies in E-Commerce: A Qualitative Study of High-Risk Transactions

The recent Covid-19 pandemic has led to a sharp increase in online shopping. While the promises of shopping on e-commerce platforms are vast, there are simultaneously novel and exacerbated risks compared to traditional brick-and-mortar retail purchases. Existing research outlines numerous risk dimensions associated with online shopping. In addition, scholars examine the underlying reasons for consumers' risk perceptions, such as the inability of physical quality checks. However, there is a lack of research investigating how consumers attempt to navigate and mitigate risk perceptions when confronted with a high-risk online transaction. To address this research gap, we conducted 18 semi-structured interviews with consumers who had recently performed an online transaction associated with high-risk perceptions. Our study contributes to the existing literature by identifying an affective and cognitive risk mitigation strategy and respective underlying mechanisms. Notably, we find that online social networks play a central role in shaping consumers' risk perceptions

Wrist-worn pervasive gaze interaction

This paper addresses gaze interaction for smart home control, conducted from a wrist-worn unit. First we asked ten people to enact the gaze movements they would propose for e.g. opening a door or adjusting the room temperature. On basis of their suggestions we built and tested different versions of a prototype applying off-screen stroke input. Command prompts were given to twenty participants by text or arrow displays. The success rate achieved by the end of their first encounter with the system was 46% in average; it took them 1.28 seconds to connect with the system and 1.29 seconds to make a correct selection. Their subjective evaluations were positive with regard to the speed of the interaction. We conclude that gaze gesture input seems feasible for fast and brief remote control of smart home technology provided that robustness of tracking is improved

Sensitivity analysis and model order reduction for random linear dynamical systems

Abstract We consider linear dynamical systems defined by differential algebraic equations. The associated input-output behaviour is given by a transfer function in the frequency domain. Physical parameters of the dynamical system are replaced by random variables to quantify uncertainties. We analyse the sensitivity of the transfer function with respect to the random variables. Total sensitivity coefficients are computed by a nonintrusive and by an intrusive method based on the expansions in series of the polynomial chaos. In addition, a reduction of the state space is applied in the intrusive method. Due to the sensitivities, we perform a model order reduction within the random space by changing unessential random variables back to constants. The error of this reduction is analysed. We present numerical simulations of a test example modelling a linear electric network

Essential role of glucose transporter GLUT3 for post-implantation embryonic development

Deletion of glucose transporter gene Slc2a3 (GLUT3) has previously been reported to result in embryonic lethality. Here, we define the exact time point of growth arrest and subsequent death of the embryo. Slc2a3−/− morulae and blastocysts developed normally, implanted in vivo, and formed egg-cylinder-stage embryos that appeared normal until day 6·0. At day 6·5, apoptosis was detected in the ectodermal cells of Slc2a3−/− embryos resulting in severe disorganization and growth retardation at day 7·5 and complete loss of embryos at day 12·5. GLUT3 was detected in placental cone, in the visceral ectoderm and in the mesoderm of 7·5-day-old wild-type embryos. Our data indicate that GLUT3 is essential for the development of early post-implanted embryos

Cold-Atmospheric Plasma Induces Tumor Cell Death in Preclinical In Vivo and In Vitro Models of Human Cholangiocarcinoma

Through the last decade, cold atmospheric plasma (CAP) has emerged as an innovative therapeutic option for cancer treatment. Recently, we have set up a potentially safe atmospheric pressure plasma jet device that displays antitumoral properties in a preclinical model of cholangiocarcinoma (CCA), a rare and very aggressive cancer emerging from the biliary tree with few efficient treatments. In the present study, we aimed at deciphering the molecular mechanisms underlying the antitumor effects of CAP towards CCA in both an in vivo and in vitro context. In vivo, using subcutaneous xenografts into immunocompromised mice, CAP treatment of CCA induced DNA lesions and tumor cell apoptosis, as evaluated by 8-oxoguanine and cleaved caspase-3 immunohistochemistry, respectively. The analysis of the tumor microenvironment showed changes in markers related to macrophage polarization. In vitro, the incubation of CCA cells with CAP-treated culture media (i.e., plasma-activated media, PAM) led to a dose response decrease in cell survival. At molecular level, CAP treatment induced double-strand DNA breaks, followed by an increased phosphorylation and activation of the cell cycle master regulators CHK1 and p53, leading to cell cycle arrest and cell death by apoptosis. In conclusion, CAP is a novel therapeutic option to consider for CCA in the future

Constraining the marine strontium budget with natural strontium isotope fractionations (⁸⁷Sr/⁸⁶Sr*, δ^88/86Sr) of carbonates, hydrothermal solutions and river waters

We present strontium (Sr) isotope ratios that, unlike traditional 87Sr/86Sr data, are not normalized to a fixed 88Sr/86Sr ratio of 8.375209 (defined as δ88/86Sr = 0 relative to NIST SRM 987). Instead, we correct for isotope fractionation during mass spectrometry with a 87Sr–84Sr double spike. This technique yields two independent ratios for 87Sr/86Sr and 88Sr/86Sr that are reported as (87Sr/86Sr*) and (δ88/86Sr), respectively. The difference between the traditional radiogenic (87Sr/86Sr normalized to 88Sr/86Sr = 8.375209) and the new 87Sr/86Sr* values reflect natural mass-dependent isotope fractionation. In order to constrain glacial/interglacial changes in the marine Sr budget we compare the isotope composition of modern seawater ((87Sr/86Sr*, δ88/86Sr)Seawater) and modern marine biogenic carbonates ((87Sr/86Sr*, δ88/86Sr)Carbonates) with the corresponding values of river waters ((87Sr/86Sr*, δ88/86Sr)River) and hydrothermal solutions ((87Sr/86Sr*, δ88/86Sr)HydEnd) in a triple isotope plot. The measured (87Sr/86Sr*, δ88/86Sr)River values of selected rivers that together account for not, vert, similar18% of the global Sr discharge yield a Sr flux-weighted mean of (0.7114(8), 0.315(8)‰). The average (87Sr/86Sr*, δ88/86Sr)HydEnd values for hydrothermal solutions from the Atlantic Ocean are (0.7045(5), 0.27(3)‰). In contrast, the (87Sr/86Sr*, δ88/86Sr)Carbonates values representing the marine Sr output are (0.70926(2), 0.21(2)‰). We estimate the modern Sr isotope composition of the sources at (0.7106(8), 0.310(8)‰). The difference between the estimated (87Sr/86Sr*, δ88/86Sr)input and (87Sr/86Sr*, δ88/86Sr)output values reflects isotope disequilibrium with respect to Sr inputs and outputs. In contrast to the modern ocean, isotope equilibrium between inputs and outputs during the last glacial maximum (10–30 ka before present) can be explained by invoking three times higher Sr inputs from a uniquely “glacial” source: weathering of shelf carbonates exposed at low sea levels. Our data are also consistent with the “weathering peak” hypothesis that invokes enhanced Sr inputs resulting from weathering of post-glacial exposure of abundant fine-grained material