A simulation based approach on robust airline job pairing

Job paring, i.e. the composition of duty rosters from single activities, is an important part of the airline operations planning process. With labor costs being a major factor in an airline's cost structure, such personnel schedules have to ensure efficiency to be of practical relevance. At the same time they have to improve customer acceptance by offering best possible robustness, keeping inevitable local delays from spreading through the airline's flight network. In this paper we present a project currently in development which aims for generating robust personnel schedules for airline operations. The resulting tool set will allow us to effectively allocate flight personnel, using optimization and simulation techniques to generate and compare schedules with respect to their applicability and their demand for standby personnel, and to evaluate them prior to their implementation in the field. This paper begins with a short introduction of the airline planning process, focusing on the job pairing problem. We then describe our project, presenting our optimization and simulation approaches

In vivo aminoacylation and 'processing' of turnip yellow mosaic virus RNA in Xenopus laevis oocytes [29]

IT is now well established that several plant and animal virus RNAs possess a 'tRNA-like' structure, as they are recognised in vitro by many tRNA-specific enzymes. To approach the problem of the possible physiological significance of these structures for the development of the virus, it seemed important to determine whether they are also recognised in vivo. The most logical approach would have been to use plant protoplast systems to study the behaviour of viral genomes in the infected cells. However, because such systems are still difficult to control, we decided to use the oocyte system. We describe here how turnip yellow mosaic virus (TYMV) RNA, which can be aminoacylated in vitro by valine1, was microinjected into Xenopus laevis oocytes, incubated in the presence of 3H-valine and the RNA charged in vivo analysed. We conclude that TYMV RNA, the 3′ terminal sequence of which is -CC (refs 2, 3), is amino-acylated in vivo. This indicates that the viral RNA is recognised by the oocyte tRNA nucleotidyltransferase and valyl-tRNA synthetase. Furthermore, the TYMV Val-RNA recovered after the in vivo reaction is fragmented and migrates between 4S and 5S RNA markers. This implies that (an) RNase(s) split(s) the viral genome, liberating this tRNA-like structure. © 1978 Nature Publishing Group.SCOPUS: le.jinfo:eu-repo/semantics/publishe