2 research outputs found
Formation Channels for Population III Stars at Cosmic Dawn
We present a study of the co-evolution of a population of primordial
star-forming minihalos at Cosmic Dawn. In this study, we highlight the
influence of individual Population III stars on the ability of nearby minihalos
to form sufficient molecular hydrogen to undergo star formation of their own.
In the absence of radiation, we find the minimum halo mass required to bring
about collapse and star formation to be 10^5 Msun, which then increases to 10^6
Msun after two stars have formed. We find an inverse relationship between the
mass of a halo and the time required for it to recover its molecular gas after
being disrupted by radiation from a nearby star. We also take advantage of the
extremely high resolution to investigate the effects of major and minor mergers
on the gas content of star-forming minihalos. Contrary to previous claims of
fallback of supernova ejecta, we find that minihalos evacuated after hosting
Pop III stars primarily recover gas through mergers with undisturbed halos. We
identify an intriguing type of major merger between recently evacuated halos
and gas-rich ones, finding that these "dry" mergers accelerate star formation
instead of suppressing it like their low redshift counterparts. We attribute
this to the gas-poor nature of one of the merging halos resulting in no
significant rise in temperature or turbulence and instead inducing a rapid
increase in central density and hydrostatic pressure. This constitutes a novel
formation pathway for Pop III stars and establishes major mergers as
potentially the primary source of gas, thus redefining the role of major
mergers at this epoch.Comment: 14 pages, 12 figures, submitted to MNRA
Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTICâHF: baseline characteristics and comparison with contemporary clinical trials
Aims:
The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTICâHF) trial. Here we describe the baseline characteristics of participants in GALACTICâHF and how these compare with other contemporary trials.
Methods and Results:
Adults with established HFrEF, New York Heart Association functional class (NYHA)ââ„âII, EF â€35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokineticâguided dosing: 25, 37.5 or 50âmg bid). 8256 patients [male (79%), nonâwhite (22%), mean age 65âyears] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NTâproBNP 1971âpg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTICâHF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressureâ<â100âmmHg (n = 1127), estimated glomerular filtration rate <â30âmL/min/1.73 m2 (n = 528), and treated with sacubitrilâvalsartan at baseline (n = 1594).
Conclusions:
GALACTICâHF enrolled a wellâtreated, highârisk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation