Experimental Aerodynamic and Aeroelastic Investigation of a Transonic Compressor Rotor with Reduced Blade Count

This study investigates the aerodynamic and aeroelastic characteristics of a transonic axial compressor, focusing on blade count reduced rotor behavior. The analysis is based on experiments, conducted at the Transonic Compressor Darmstadt test rig at Technical University of Darmstadt and compulsory simulations. In order to obtain measurement data for the detailed aerodynamic and aeroelastic investigation, extensive steady and unsteady instrumentation was applied. Besides transient measurements at the stability limit to determine the operating range and limiting phenomena, performance measurements were performed, presenting promising results with respect to the capabilities of blade count reduced rotors. Close to the stability limit, aerodynamic disturbances like radial vortices were detected for both rotors, varying in size, count, speed and trajectory. Comparing the rotor configurations results in different stability limits along the compressor map as well as varying aeromechanical behavior. Those effects can partially be traced to the variation in blade pitch and associated aerodynamics

Secondary Sclerosing Cholangitis in Critically Ill Patients Alters the Gut–Liver Axis: A Case Control Study

Secondary sclerosing cholangitis in critically ill patients (SC-CIP) occurs after long-term intensive care treatment. This study aimed to assess the gut–liver axis in SC-CIP. Stool microbiome composition, gut permeability, bacterial translocation and serum bile acid profiles of 18 SC-CIP patients compared to 11 patients after critical illness without liver disease (CIP controls), 21 patients with cirrhosis and 21 healthy controls were studied. 16S rDNA was isolated from stool and sequenced using the Illumina technique. Diamine oxidase, zonulin, soluble CD14 (sCD14) and lipopolysaccharide binding protein were measured in serum and calprotectin in stool. Serum bile acids were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Reduced microbiome alpha diversity and altered beta diversity were seen in SC-CIP, CIP controls and cirrhosis compared to healthy controls. SC-CIP patients showed a shift towards pathogenic taxa and an oralization. SC-CIP, CIP controls and cirrhotic patients presented with impaired gut permeability, and biomarkers of bacterial translocation were increased in SC-CIP and cirrhosis. Total serum bile acids were elevated in SC-CIP and cirrhosis and the bile acid profile was altered in SC-CIP, CIP controls and cirrhosis. In conclusions, observed alterations of the gut–liver axis in SC-CIP cannot solely be attributed to liver disease, but may also be secondary to long-term intensive care treatment

On the reproducibility of extrusion-based bioprinting: round robin study on standardization in the field

The outcome of three-dimensional (3D) bioprinting heavily depends, amongst others, on the interaction between the developed bioink, the printing process, and the printing equipment. However, if this interplay is ensured, bioprinting promises unmatched possibilities in the health care area. To pave the way for comparing newly developed biomaterials, clinical studies, and medical applications (i.e. printed organs, patient-specific tissues), there is a great need for standardization of manufacturing methods in order to enable technology transfers. Despite the importance of such standardization, there is currently a tremendous lack of empirical data that examines the reproducibility and robustness of production in more than one location at a time. In this work, we present data derived from a round robin test for extrusion-based 3D printing performance comprising 12 different academic laboratories throughout Germany and analyze the respective prints using automated image analysis (IA) in three independent academic groups. The fabrication of objects from polymer solutions was standardized as much as currently possible to allow studying the comparability of results from different laboratories. This study has led to the conclusion that current standardization conditions still leave room for the intervention of operators due to missing automation of the equipment. This affects significantly the reproducibility and comparability of bioprinting experiments in multiple laboratories. Nevertheless, automated IA proved to be a suitable methodology for quality assurance as three independently developed workflows achieved similar results. Moreover, the extracted data describing geometric features showed how the function of printers affects the quality of the printed object. A significant step toward standardization of the process was made as an infrastructure for distribution of material and methods, as well as for data transfer and storage was successfully established

On the reproducibility of extrusion-based bioprinting: round robin study on standardization in the field

The outcome of three-dimensional (3D) bioprinting heavily depends, amongst others, on the interaction between the developed bioink, the printing process, and the printing equipment. However, if this interplay is ensured, bioprinting promises unmatched possibilities in the health care area. To pave the way for comparing newly developed biomaterials, clinical studies, and medical applications (i.e. printed organs, patient-specific tissues), there is a great need for standardization of manufacturing methods in order to enable technology transfers. Despite the importance of such standardization, there is currently a tremendous lack of empirical data that examines the reproducibility and robustness of production in more than one location at a time. In this work, we present data derived from a round robin test for extrusion-based 3D printing performance comprising 12 different academic laboratories throughout Germany and analyze the respective prints using automated image analysis (IA) in three independent academic groups. The fabrication of objects from polymer solutions was standardized as much as currently possible to allow studying the comparability of results from different laboratories. This study has led to the conclusion that current standardization conditions still leave room for the intervention of operators due to missing automation of the equipment. This affects significantly the reproducibility and comparability of bioprinting experiments in multiple laboratories. Nevertheless, automated IA proved to be a suitable methodology for quality assurance as three independently developed workflows achieved similar results. Moreover, the extracted data describing geometric features showed how the function of printers affects the quality of the printed object. A significant step toward standardization of the process was made as an infrastructure for distribution of material and methods, as well as for data transfer and storage was successfully established

Structural knowledge (re-)presentation: theoretical concepts and practical relevance

Verschiedene Darstellungsmöglichkeiten von Wissensstrukturen werden anhand von Jonassen et al. (1993) in eine Rahmenstruktur eingeordnet: Techniken zur Repräsentation, zur Übertragung/Vermittlung (i.S. von Instruktion) und zum Erwerb von Wissenssstrukturen (i.S. von Selbstinstruktion). Der Einsatz von Strukturdarstellungen bei der Wissensdiagnose wird genauer betrachtet, dabei werden differenzierte, hauptsächlich in der wissenschaftlichen Diagnostik verwendete Methoden ebenso angesprochen wie Möglicheiten vereinfachter Anwendungen in der Unterrichtspraxis. Verschiedene Möglichkeiten des Einsatzes bei der Wissensvermittlung werden vorgestellt und Forschungsdesiderata anhand eines Schemas didaktischer und psychologischer Lernschritte aufgedeckt. (DIPF/Orig.

Cooperative Learning in a Multimedia Learning Environment - A Pilot Study in the Field of Professional Further Education

Ausgehend von verschiedenen kooperativen Lernmodellen wurden Annahmen im Leistungs-, interpersonalen und affektiven Bereich bezüglich kooperativen Lernens am Computer untersucht. Versuchspersonen waren erwachsene Lerner beiderlei Geschlechts, die ein multimediales Lernprogramm als berufliche Weiterbildungsmaßnahme bearbeiteten. 50 Vpn nahmen an der Kooperationsbedingung teil, während 25 Vpn in der gewohnten Individualbedingung als Kontrollgruppe dienten. Entsprechend unserer Annahmen zeigte sich ein Vorteil der Kooperationsbedingung beim computerunterstützten Lernen, der durch instruktionstechnische Änderungen und Kooperationsstrategien vermutlich verbesserungsfähig ist. (DIPF/Orig.)Based on cooperative learning models the present study investigated the special effects of performance, interpersonal relations and affective variables in a computer-based cooperative learning environment. Subjects were male and female adults, studying a multimedia learning program as professional training. There were 50 subjects working in cooperative settings, while 25 subjects worked individualized as control group. According to our assumptions the subjects benefit from being paired. There seems to be a further profit in cooperative learning by changing instructions and cooperative strategies. (DIPF/Orig.