35 research outputs found

    An adaptive finite-volume method for a model of two-phase pedestrian flow

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    A flow composed of two populations of pedestrians moving in different directions is modeled by a two-dimensional system of convection-diffusion equations. An efficient simulation of the two-dimensional model is obtained by a finite-volume scheme combined with a fully adaptive multiresolution strategy. Numerical tests show the flow behavior in various settings of initial and boundary conditions, where different species move in countercurrent or perpendicular directions. The equations are characterized as hyperbolic-elliptic degenerate, with an elliptic region in the phase space, which in one space dimension is known to produce oscillation waves. When the initial data are chosen inside the elliptic region, a spatial segregation of the populations leads to pattern formation. The entries of the diffusion-matrix determine the stability of the model and the shape of the patterns

    Improved calibration procedures for the EM27/SUN spectrometers of the COllaborative Carbon Column Observing Network (COCCON)

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    In this study, an extension on the previously reported status of the COllaborative Carbon Column Observing Network\u27s (COCCON) calibration procedures incorporating refined methods is presented. COCCON is a global network of portable Bruker EM27/SUN FTIR spectrometers for deriving column-averaged atmospheric abundances of greenhouse gases. The original laboratory open-path lamp measurements for deriving the instrumental line shape (ILS) of the spectrometer from water vapour lines have been refined and extended to the secondary detector channel incorporated in the EM27/SUN spectrometer for detection of carbon monoxide (CO). The refinements encompass improved spectroscopic line lists for the relevant water lines and a revision of the laboratory pressure measurements used for the analysis of the spectra. The new results are found to be in good agreement with those reported by Frey et al. (2019) and discussed in detail. In addition, a new calibration cell for ILS measurements was designed, constructed and put into service. Spectrometers calibrated since January 2020 were tested using both methods for ILS characterization, open-path (OP) and cell measurements. We demonstrate that both methods can detect the small variations in ILS characteristics between different spectrometers, but the results of the cell method indicate a systematic bias of the OP method. Finally, a revision and extension of the COCCON network instrument-to-instrument calibration factors for XCO2, XCO and XCH4 is presented, incorporating 47 new spectrometers (of 83 in total by now). This calibration is based on the reference EM27/SUN spectrometer operated by the Karlsruhe Institute of Technology (KIT) and spectra collected by the collocated TCCON station Karlsruhe. Variations in the instrumental characteristics of the reference EM27/SUN from 2014 to 2017 were detected, probably arising from realignment and the dual-channel upgrade performed in early 2018. These variations are considered in the evaluation of the instrument-specific calibration factors in order to keep all tabulated calibration results consistent

    Veraenderung der Arbeitsorganisation und Folgen fuer den Personaleinsatz Mehr Zeitsouveraenitaet durch Zeitkontenmodelle?

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    'Die Arbeitszeitgestaltung steht in einem gesellschaftlichen Spannungsfeld: Waehrend die Unternehmen unter wachsendem wirtschaftlichen Druck ein Interesse an flexiblem Personaleinsatz haben, koennen neue Arbeitszeitmodelle fuer die Arbeitnehmerinnen und Arbeitnehmer Spielraeume eroeffnen, ihre Arbeitszeit mehr nach persoenlichen Interessen zu gestalten. Den Betriebsraeten faellt dabei - nicht zuletzt aufgrund ihrer Mitbestimmungsrechte - eine wesentliche Rolle bei der Gestaltung der betrieblichen Arbeitszeitorganisation zu. Die Broschuere arbeitet anhand von Praxisbeispielen aus der Ernaehrungsindustrie die mit den veraenderten Organisationsablaeufen verbundenen Anforderungen auf. Beispiele neuer Formen des Personaleinsatzes und der Arbeitsorganisation, die den Interessen aller Beteiligten entgegenkommen, werden dargestellt und die Erfahrungen mit Zeitkontenmodellen ausgewertet.' (Autorenreferat, IAB-Doku)SIGLEAvailable from IAB-90-0BW0-206600 BD 503 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

    AN ADAPTIVE FINITE-VOLUME METHOD FOR A MODEL OF TWO-PHASE PEDESTRIAN FLOW

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    A flow composed of two populations of pedestrians moving in different directions is modeled by a two-dimensional system of convection-diffusion equations. An efficient simulation of the two-dimensional model is obtained by a finite-volume scheme combined with a fully adaptive multiresolution strategy. Numerical tests show the flow behavior in various settings of initial and boundary conditions, where different species move in countercurrent or perpendicular directions. The equations are characterized as hyperbolic-elliptic degenerate, with an elliptic region in the phase space, which in one space dimension is known to produce oscillation waves. When the initial data are chosen inside the elliptic region, a spatial segregation of the populations leads to pattern formation. The entries of the diffusion-matrix determine the stability of the model and the shape of the patterns

    Early initiation of MARS® dialysis in Amanita phalloides-induced acute liver injury prevents liver transplantation

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    Amanita phalloides is the most relevant mushroom intoxication leading to acute liver failure. The two principal groups of toxins, the amatoxins and the phallotoxins, are small oligopeptides highly resistant to chemical and physical influences. The amatoxins inhibit eukaryotic RNA polymerase II causing transcription arrest affecting mainly metabolically highly active cells like hepatocytes and renal cells. The clinically most characteristic symptom is a 6-40 h lag phase before onset of gastrointestinal symptoms and the rapid progression of acute liver failure leading to multi-organ failure and death within a week if left untreated. Extracorporeal albumin dialysis (ECAD) was reported to improve patient’s outcome or facilitate bridging to transplantation. In our tertiary center, out of nine intoxicated individuals from five non-related families six patients presented with acute liver injury; all of them were treated with ECAD using the MARS® system. Four of them were listed on admission for high urgency liver transplantation. In addition to standard medical treatment for Amanita intoxication we initiated ECAD once patients were admitted to our center. Overall 16 dialysis sessions were performed. All patients survived with full native liver recovery without the need for transplantation. ECAD was well tolerated; no severe adverse events were reported during treatment. Coagulopathy resolved within days in all patients, and acute kidney injury in all but one individual. In conclusion, ECAD is highly effective in treating intoxication with Amanita phalloides. Based on these experiences we suggest early initiation and repeated sessions depending on response to ECAD with the chance of avoiding liver transplantation
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