Physical Processes in Star Formation

© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00693-8.Star formation is a complex multi-scale phenomenon that is of significant importance for astrophysics in general. Stars and star formation are key pillars in observational astronomy from local star forming regions in the Milky Way up to high-redshift galaxies. From a theoretical perspective, star formation and feedback processes (radiation, winds, and supernovae) play a pivotal role in advancing our understanding of the physical processes at work, both individually and of their interactions. In this review we will give an overview of the main processes that are important for the understanding of star formation. We start with an observationally motivated view on star formation from a global perspective and outline the general paradigm of the life-cycle of molecular clouds, in which star formation is the key process to close the cycle. After that we focus on the thermal and chemical aspects in star forming regions, discuss turbulence and magnetic fields as well as gravitational forces. Finally, we review the most important stellar feedback mechanisms.Peer reviewedFinal Accepted Versio

European meeting in the IOBC/WPRS working group "insect pathogens and insect parasites nematodes" special theme "microbial control of pests in sustainable agriculture"

The pink borer, #Sesamia cretica Lederer (#Lepidoptera : #Noctuidae), is a main pest of maize in Egypt. Attacks by #S. cretica are usually high on early plantations of April, when the first generation of adults emerge after a period of larval hibernation. The present study aimed to evaluate the feasibility of the granulosis virus of #S. cretica, recently isolated by Fediere et al. (1993) as a microbiological agent. A field experiment was conducted in 1997 at Sakha Agricultural Research Station, Kafr El-Sheikh governorate, North of the Nile delta, where heavy natural infestation by #S. cretica is of frequent occurrence on early plantations. The experimental design was randomized blocks with seven replications and five treatments. Treatments were control (T1), the currently recommended chemical insecticide (methomyl, 640 g active ingredient per hectare) (two sprayings, three and five weeks after sowing) (T2), and three treatments with highly purified suspensions of virus in water at three different doses (two sprayings, three and five weeks after sowing). The lowest dose of the virus insecticide (T3) was 60 g of granules per hectare (i.e. 7.4 x 10 to the 15th power I.B./ha). The other doses were double this dose (T4) and five times this dose (T5). Molasses was added to the virus suspension at a rate of 10% as a sticker and a feeding stimulant. Samples of 20 plants per plot were taken every week for four successive weeks from the day of the first treatment. Population density in the control was close to one borer per stem during the first three weeks and decreased to 0.2 borer per stem during the fourth week. Comparison between tested treatments using analysis of variance and Newman-Keuls test showed that the viral suspensions had an efficiency not different from that of methomyl, and that populations were significantly reduced in the sprayed plots in comparison with the control (about 70% reduction)... (D'après résumé d'auteur