R-process enrichment from a single event in an ancient dwarf galaxy

Elements heavier than zinc are synthesized through the (r)apid and (s)low neutron-capture processes. The main site of production of the r-process elements (such as europium) has been debated for nearly 60 years. Initial studies of chemical abundance trends in old Milky Way halo stars suggested continual r-process production, in sites like core-collapse supernovae. But evidence from the local Universe favors r-process production mainly during rare events, such as neutron star mergers. The appearance of a europium abundance plateau in some dwarf spheroidal galaxies has been suggested as evidence for rare r-process enrichment in the early Universe, but only under the assumption of no gas accretion into the dwarf galaxies. Cosmologically motivated gas accretion favors continual r-process enrichment in these systems. Furthermore, the universal r-process pattern has not been cleanly identified in dwarf spheroidals. The smaller, chemically simpler, and more ancient ultra-faint dwarf galaxies assembled shortly after the first stars formed, and are ideal systems with which to study nucleosynthesis events such as the r-process. Reticulum II is one such galaxy. The abundances of non-neutron-capture elements in this galaxy (and others like it) are similar to those of other old stars. Here, we report that seven of nine stars in Reticulum II observed with high-resolution spectroscopy show strong enhancements in heavy neutron-capture elements, with abundances that follow the universal r-process pattern above barium. The enhancement in this "r-process galaxy" is 2-3 orders of magnitude higher than that detected in any other ultra-faint dwarf galaxy. This implies that a single rare event produced the r-process material in Reticulum II. The r-process yield and event rate are incompatible with ordinary core-collapse supernovae, but consistent with other possible sites, such as neutron star mergers.Comment: Published in Nature, 21 Mar 2016: http://dx.doi.org/10.1038/nature1742

Pleosporales

One hundred and five generic types of Pleosporales are described and illustrated. A brief introduction and detailed history with short notes on morphology, molecular phylogeny as well as a general conclusion of each genus are provided. For those genera where the type or a representative specimen is unavailable, a brief note is given. Altogether 174 genera of Pleosporales are treated. Phaeotrichaceae as well as Kriegeriella, Zeuctomorpha and Muroia are excluded from Pleosporales. Based on the multigene phylogenetic analysis, the suborder Massarineae is emended to accommodate five families, viz. Lentitheciaceae, Massarinaceae, Montagnulaceae, Morosphaeriaceae and Trematosphaeriaceae

Possible house-keeping and other draft proposals to clarify or enhance the naming of fungi within the International Code of Nomenclature for algae, fungi, and plants (ICN)

The 10th International Mycological Congress (IMC10), to be held in August 2014, will be the last before the 19th International Botanical Congress (IBC) scheduled for July 2017 at which changes in the ICN will be adopted. IMC10 will therefore be the last opportunity for mycologists as a whole to debate and propose clarifications and other changes they would like to see made in the ICN which was adopted in Melbourne in 2011. In order to stimulate debate, draft proposals are presented here on ten topics: terminology of the new lists; protection against unlisted names; priority for sexual morph typified names; removal of exemptions for lichen-forming fungi; extension of sanctioning to additional works; extending conservation to additional ranks; names with the same epithet; registration of typifications subsequent to valid publication; sequenced epitypes; and generic homonyms in other kingdoms. It is anticipated that the draft proposals presented here will be abandoned, refined, or supplemented by debates at the Genera and Genomes symposium in Amsterdam in April 2014 and during IMC10, and also by other comments received from individual mycologists or other bodies. Formal proposals will then be prepared for presentation and decision at the IBC in 2017

A Multivariate Analysis of the Self-Determination of Adolescents

Self-determination, Quality of life, Self-efficacy, Adolescents, Assertiveness,