Do new records of macrofungi indicate warming of their habitats in terrestrial Antarctic ecosystems?

Relatively few macrofungi have been historically described from terrestrial environments of the Antarctic Peninsula and its associated archipelagos which are characterized by a moss-dominated vegetation, most of them preferentially or obligatorily associated with bryophytes. During the study of the influence of penguin rockeries to moss communities on the South Shetland Islands, the bryophilous basidiomycetes Rimbachia bryophila and Arrhenia cf. lilacinicolor were found for the first time on King George Island, growing on carpets of Sanionia uncinata. Other bryophilous fungi previously recorded in the same region are Arrhenia antarctica, Omphalina pyxidata and the rare Simocybe antarctica. The detection of the supposedly parasitic R. bryophila, together with other new observations of macrofungi on different hosts in the Antarctic bryoflora could indicate increased sexual reproduction. The likely increase of reproduction as an effect of warming on the terrestrial antarctic tundra should be proven by follow up field studies

Competition between native Antarctic vascular plants and invasive Poa annua changes with temperature and soil nitrogen availability

Over the last decades human have introduced non-native organisms to Antarctica, including the grass species Poa annua. This non-native grass under constant growth temperatures has been shown negatively affect the growth of the only two native Antarctic vascular plants, Deschampsia antarctica and Colobanthus quitensis, under constant growth temperatures. However, whether there are changes in the interaction between these species under warmer conditions is an important question. In cold ecosystems, soil nutrient status directly affects plant responses to increases in temperature and Antarctic soils are highly variable in nutrient supply. Thus, in this study we experimentally assessed the interaction between the non-native Poa with the two native Antarctic vascular plant species at two different temperatures and levels of nutrient availability. Individual mats of the study species were collected in King George Island, and then transported to Concepcion where we conducted competition experiments. In the first experiment we used soil similar to that of Antarctica and plants in competition were grown at two temperatures: 5 degrees/2 degrees and 11 degrees/5 degrees C (day/ night temperature). In a second experiment plants were grown in these two temperature regimes, but we varied nitrogen (N) availability by irrigating plants with Hoagland solutions that contained 8000 or 300 mu M of N. Overall, Poa exerted a competitive effect on Deschampsia but only at the higher temperature and higher N availability. At 5 degrees/11 degrees C the competitive response of Deschampsia to Poa was of similar magnitude to the competitive effect of P. Deschatnpsia, and the competitive effect was greater with at low N. The competitive effect of Poa was similar to the competitive response of Colobanthus to Poa at both temperatures and N levels. Thus, at low temperatures and N soil content the native Antarctic species might withstand Poa invasion, but this might change with climate warming

Comparison of seven prognostic tools to identify low-risk pulmonary embolism in patients aged <50 years

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Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements