Extreme environments simplify reassembly of communities of arbuscular mycorrhizal fungi

The ecological impacts of long-term (press) disturbance on mechanisms regulating the relative abundance (i.e., commonness or rarity) and temporal dynamics of species within a community remain largely unknown. This is particularly true for the functionally important arbuscular mycorrhizal (AM) fungi; obligate plant-root endosym­bionts that colonize more than two-thirds of terrestrial plant species. Here, we use high-resolution amplicon sequencing to examine how AM fungal communities in a specific extreme ecosystem—mofettes or natural CO2 springs caused by geological CO2 exhalations—are affected by long-term stress. We found that in mofettes, specific and temporally stable communities form as a subset of the local metacommunity. These communities are less diverse and dominated by adapted, “stress tolerant” taxa. Those taxa are rare in control locations and more benign environments worldwide, but show a stable temporal pattern in the extreme sites, consistently dominating the communities in grassland mofettes. This pattern of lower diversity and high dominance of specific taxa has been confirmed as relatively stable over several sampling years and is independently observed across multiple geographic locations (mofettes in different countries). This study implies that the response of soil microbial community composition to long-term stress is relatively predictable, which can also reflect the community response to other anthropogenic stressors (e.g., heavy metal pollution or land use change). Moreover, as AM fungi are functionally differentiated, with different taxa providing different benefits to host plants, changes in community structure in response to long-term environmental change have the potential to impact terrestrial plant communities and their productivity

Praćenje srednje moždane arterije transkranijskom dopler sonografijom tijekom stimulacije govora u afatičnih bolesnika

Hemodynamic changes can be noninvasively real-time monitored in stroke patients by means of transcranial Doppler sonography (TCD). The aim of this pilot study was to assess hemodynamic changes in both middle cerebral arteries (MCA) in aphasic stroke patients by means of TCD during verbal stimulation. Eight aphasic patients with stroke in the territory of the left MCA were tested by modified Boston Diagnostic Aphasia Examination (BDAE) within 3 days of stroke onset. Both MCA were monitored simultaneously by means of TCD with 2 MHz probes. Basic MCA mean blood flow velocity (MBFV) values were assessed and monitored during verbal stimulation. Verbal stimulation was performed with 30 photos of objects for daily usage, arranged by function. The same test was performed in 16 right-handed healthy controls. In stroke patients, the mean MBFV were 56 cm/s in the left MCA and 56 cm/s in the right MCA. A mean 30% increase was observed in the left MCA and 22% in the right MCA. In healthy controls, a mean 21.7% increase was observed in the left MCA and 18% in the right MCA. A trend toward higher percentage of MBFV increase was observed in the left MCA during verbal stimulations in aphasic patients as compared to control subjects.Promjene moždane hemodinamike u srednjoj moždanoj arteriji (SMA) u bolesnika s moždanim udarom u irigacijskom području lijeve moždane arterije, te s posljedičnom afazijom mogu se neinvazivno pratiti pomoću funkcionalne transkranijske dopler sonografije (fTCD). Pritom se kao funkcionalni podražaj može koristiti stimulacija govora u obliku logopedskih vježbi. Da bismo procijenili aktivaciju SMA tijekom receptivne i ekspresivne verbalne stimulacije, ispitivanje afazije proveli smo modificiranim bostonskim dijagnostičkim testom u irigacijskom području lijeve SMA kod 8 bolesnika s moždanim udarom unutar 3 dana od nastanka ishemičnog moždanog udara. U obje smo SMA praćenje TCD-om proveli istodobno pomoću 2 ultrazvučne sonde frekvencija 2 MHz. Srednje brzine strujanja krvi (SBSK) u SMA procjenjivali smo i pratili prije i tijekom govorne stimulacije. Stimulaciju govorom proveo je logoped baterijom logopedskih vježbi, te zadacima imenovanja uz pomoć 30 fotografija predmeta svakodnevne uporabe grupiranih prema funkcijama. Isto ispitivanje je provedeno u 16 zdravih dešnjaka. Srednje brzine strujanja krvi bile su: 56 cm/s u lijevoj ACM, te 56 cm/s u desnoj SMA. U lijevoj je SMA tijekom stimulacije govora zabilježen srednji 30%-tni rast SBSK, a u desnoj SMA 22%-tni rast u odnosu na mirovanje. U zdravih kontrolnih osoba u lijevoj je SMA zabilježen porast SBSK od 21,7%, a u desnoj SMA od 18%. Uočen je trend rasta SBSK u lijevoj SMA tijekom stimulacije govora u afatičnih bolesnika u usporedbi sa zdravim kontrolnim osobama

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