Jet modification via π 0 -hadron correlations in Au+Au collisions at √sNN = 200 GeV

High-momentum two-particle correlations are a useful tool for studying jet-quenching effects in the quark-gluon plasma. Angular correlations between neutral-pion triggers and charged hadrons with transverse momenta in the range 4–12 GeV/c and 0.5–7 GeV/c, respectively, have been measured by the PHENIX experiment in 2014 for Au+Au collisions at √sNN = 200 GeV. Suppression is observed in the yield of high-momentum jet fragments opposite the trigger particle, which indicates jet suppression stemming from in-medium partonic energy loss, while enhancement is observed for low-momentum particles. The ratio and differences between the yield in Au+Au collisions and p+p collisions, IAA and ∆AA, as a function of the trigger-hadron azimuthal separation, ∆ϕ, are measured for the first time at the Relativistic Heavy Ion Collider. These results better quantify how the yield of low-pT associated hadrons is enhanced at wide angle, which is crucial for studying energy loss as well as medium-response effects

Systematic study of nuclear effects in p+Al, p+Au, d+Au, and 3He+Au collisions at √sNN = 200 GeV using π 0 production

The PHENIX collaboration presents a systematic study of inclusive π 0 production from p+p, p+Al, p+Au, d+Au, and 3He+Au collisions at √sNN = 200 GeV. Measurements were performed with different centrality selections as well as the total inelastic, 0%–100%, selection for all collision systems. For 0%–100% collisions, the nuclear-modification factors, RxA, are consistent with unity for pT above 8 GeV/c, but exhibit an enhancement in peripheral collisions and a suppression in central collisions. The enhancement and suppression characteristics are similar for all systems for the same centrality class. It is shown that for high-pT -π 0 production, the nucleons in the d and 3He interact mostly independently with the Au nucleus and that the counter intuitive centrality dependence is likely due to a physical correlation between multiplicity and the presence of a hard scattering process. These observations disfavor models where parton energy loss has a significant contribution to nuclear modifications in small systems. Nuclear modifications at lower pT resemble the Cronin effect – an increase followed by a peak in central or inelastic collisions and a plateau in peripheral collisions. The peak height has a characteristic ordering by system size as p+Au > d+Au > 3He+Au > p+Al. For collisions with Au ions, current calculations based on initial state cold nuclear matter effects result in the opposite order, suggesting the presence of other contributions to nuclear modifications, in particular at lower pT

Intensivists' Reported Management of Critical Bronchiolitis: More Data and New Guidelines Needed

OBJECTIVES: Existing bronchiolitis guidelines do not reflect the needs of infants admitted to the PICU. This study aimed to identify PICU providers' reported practice variations and explore the need for critical bronchiolitis clinical guidelines. METHODS: Cross-sectional electronic survey available in English, Spanish, and Portuguese between November 2020 and March 2021, distributed via research networks from North and Latin America, Asia, and Australia/New Zealand. RESULTS: A total of 657 PICU providers responded, including 344 English, 204 Spanish, and 109 Portuguese. PICU providers indicated frequently using ($25$25% of time) prescribing b-2 agonists (43%-50%), systemic corticosteroids (23%-33%), antibiotics (24%-41%), and diuretics (13%-41%). Although work of breathing was the most common variable affecting providers' decision to initiate enteral feeds for nonintubated infants, hemodynamic status was the most common variable for intubated infants (82% of providers). Most respondents agreed it would be beneficial to have specific guidelines for infants with critical bronchiolitis who are requiring both noninvasive (91% agreement) and invasive (89% agreement) respiratory support. CONCLUSIONS: PICU providers report performing diagnostic and therapeutic interventions for infants with bronchiolitis more frequently than recommended by current clinical guidelines, with interventions occurring more frequently for infants requiring invasive support. More clinical research is needed to inform the creation of evidence-based guidelines specifically for infants with critical bronchiolitis.No Full Tex