Zur Berechnung plastischer Formänderungsvorgänge nach der visioplastischen Methode

Beschreibung der am Beispiel einfacher Stofffluβvorgänge durchgeführten Fehleranalyse für verschiedene Berechnungsmethoden zur Bestimmung von Formänderungsgeschwindigkeiten. Quantifizierung der Fehler bei stationärem Geschwindigkeitsfeld und bei nicht-koaxialen Formänderungsverläufen. Beurteilung der Untersuchungsergebnisse hinsichtlich der Anwendung der behandelten Berechnungsmethoden im visioplastischen Verfahren und Hinweis auf Möglichkeiten zur Reduzierung von dabei auftretenden Berechnungsfehlern.     

The realistic simulation of metalforming process chains

In this paper some actual developments concerning realistic simulation of metal forming processes by use of the finite element method are discussed. An algorithm, which was developed at the IBF, for visualisation of the material flow in a process chain is illustrated by means of the example of manufacturing a profiled ring. Further it is shown that for faster analysis also of massive forming processes the use of an explicit finite element formulation is sensible. Another contribution for realistic simulation is coupling the finite element method with physically-based material models. The integration of a dislocation density model in a finite element model is illustrated by means of the example of a hot rolling process.     

T helper cell differentiation in immune response

Significant progress has been made in understanding the maturation of antigen-specific CD4+ T helper cell responses. Recent progress centers on the network of cytokines, accessory molecules, and cell types that shapes the differentiation of distinct T helper cell subsets. Use of transgenic and knockout mice and well characterized in vivo models have helped clarify the interdependence or independence of many of these complex factors.     

Elongation of the cytoplasmic tail interferes with the fusion activity of influenza virus hemagglutinin

The hemagglutinin (HA) of fowl plague virus was lengthened and shortened by site-specific mutagenesis at the cytoplasmic tail, and the effects of these modifications on HA functions were analyzed after expression from a simian virus 40 vector. Elongation of the tail by the addition of one to six histidine (His) residues did not interfere with intracellular transport, glycosylation, proteolytic cleavage, acylation, cell surface expression, and hemadsorption. However, the ability to induce syncytia at a low pH decreased dramatically depending on the number of His residues added. Partial fusion (hemifusion), assayed by fluorescence transfer from octadecylrhodamine-labeled erythrocyte membranes, was also reduced, but even with the mutant carrying six His residues, significant transfer was observed. However, when the formation of fusion pores was examined with hydrophilic fluorescent calcein, transfer from erythrocytes to HA-expressing cells was not observed with the mutant carrying six histidine residues. The addition of different amino acids to the cytoplasmic tail of HA caused an inhibitory effect similar to that caused by the addition of His. On the other hand, a mutant lacking the cytoplasmic tail was still able to fuse at a reduced level. These results demonstrate that elongation of the cytoplasmic tail interferes with the formation and enlargement of fusion pores. Thus, the length of the cytoplasmic tail plays a critical role in the fusion process.     

A reading aid for the visually handicapped

A new reading aid for the visually handicapped is described. It consists of a normal pair of fieldglasses and a mirror system, and can be used either monocularly or binocularly. It features an unusually long working distance of 210 mm, regardless of magnification.