The Physics of Star Cluster Formation and Evolution

© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00689-4.Star clusters form in dense, hierarchically collapsing gas clouds. Bulk kinetic energy is transformed to turbulence with stars forming from cores fed by filaments. In the most compact regions, stellar feedback is least effective in removing the gas and stars may form very efficiently. These are also the regions where, in high-mass clusters, ejecta from some kind of high-mass stars are effectively captured during the formation phase of some of the low mass stars and effectively channeled into the latter to form multiple populations. Star formation epochs in star clusters are generally set by gas flows that determine the abundance of gas in the cluster. We argue that there is likely only one star formation epoch after which clusters remain essentially clear of gas by cluster winds. Collisional dynamics is important in this phase leading to core collapse, expansion and eventual dispersion of every cluster. We review recent developments in the field with a focus on theoretical work.Peer reviewe

Malignant fibrous histiocytoma of sternum: an unusual cause of pyrexia of undetermined origin.

Malignant fibrous histiocytoma of the bone is a very rare tumour mainly affecting long bones, and the most common presenting symptom is local pain. A case of malignant fibrous histiocytoma presenting with pyrexia of undetermined origin and arising in the sternum, a localization not previously described, is reported. The patient died with septic shock after multi-drug chemotherapy including high dose methotrexate treatment with citrovorum factor rescue

Influences of parturition on home range and microhabitat use of female black-faced impalas

The use of home ranges and microhabitats by female black-faced impalas Aepyceros melampus petersi was investigated using radio-telemetry over a 4-month period that coincided with parturition at Ongava Game Reserve, north-west Namibia. The aim of the study was to test how ranging patterns and microhabitat use were affected by the presence of young. The mean minimum convex polygon (MCP) home range of the 11 tracked female black-faced impalas exceeded the largest of home ranges of impalas elsewhere by at least six times, and females used significantly larger total ranges (MCPs) after birth, although (50% kernel) core areas did not change significantly. Females were more likely to be solitary or alone with a lamb in the first week of their lambs' lives than in the periods after or before that time, and they both shifted their home ranges and changed their microhabitat use after parturition. Decisions on microhabitat and space use by female black-faced impalas appeared to be affected by parturition