RESUMEN
Giant radio pulses (GRPs) are sporadic bursts emitted by some pulsars that last a few microseconds and are hundreds to thousands of times brighter than regular pulses from these sources. The only GRP-associated emission outside of radio wavelengths is from the Crab Pulsar, where optical emission is enhanced by a few percentage points during GRPs. We observed the Crab Pulsar simultaneously at x-ray and radio wavelengths, finding enhancement of the x-ray emission by 3.8 ± 0.7% (a 5.4σ detection) coinciding with GRPs. This implies that the total emitted energy from GRPs is tens to hundreds of times higher than previously known. We discuss the implications for the pulsar emission mechanism and extragalactic fast radio bursts.
RESUMEN
Young and rotation-powered neutron stars (NSs) are commonly observed as rapidly-spinning pulsars. They dissipate their rotational energy by emitting pulsar wind with electromagnetic radiation and spin down at a steady rate, according to the simple steadily-rotating magnetic dipole model. In reality, however, multiwavelength observations of radiation from the NS surface and magnetosphere have revealed that the evolution and properties of NSs are highly diverse, often dubbed as 'NS zoo'. In particular, many of young and highly magnetized NSs show a high degree of activities, such as sporadic electromagnetic outbursts and irregular changes in pulse arrival times. Importantly, their magnetic field, which are the strongest in the universe, makes them ideal laboratories for fundamental physics. A class of highly-magnetized isolated NSs is empirically divided into several subclasses. In a broad classification, they are, in the order of the magnetic field strength (B) from the highest, 'magnetars' (historically recognized as soft gamma-ray repeaters and/or anomalous x-ray pulsars), 'high-B pulsars', and (nearby) x-ray isolated NSs. This article presents an introductory review for non-astrophysicists about the observational properties of highly-magnetized NSs, and their implications. The observed dynamic nature of NSs must be interpreted in conjunction with transient magnetic activities triggered during magnetic-energy dissipation process. In particular, we focus on how the five fundamental quantities of NSs, i.e. mass, radius, spin period, surface temperature, and magnetic fields, as observed with modern instruments, change with evolution of, and vary depending on the class of, the NSs. They are the foundation for a future unified theory of NSs.
RESUMEN
OBJECTIVE: To describe intubation practices and duration of mechanical ventilation in children with status asthmaticus admitted from emergency departments (ERs) to pediatric intensive care units (PICUs). DESIGN: Retrospective cohort study using the Virtual PICU Performance System database (VPS, LLC) of children with status asthmaticus admitted to a participating PICU between December 2003 and September 2006. The primary outcome measure was intubation prior to intensive care unit (ICU) admission. Secondary outcomes included length of intubation and medical length of stay. SETTING: Thirty-five PICUs in the United States. PATIENTS: Children who were intubated and mechanically ventilated during their ICU stay for asthma and were admitted from an ER. RESULTS: A total of 4051 patients with status asthmaticus were identified. Intubation data were available from 35 of the 53 centers. Of all, 187 children were intubated for asthma, of which 157 were admitted from an ER and had complete data. Of all, 85 patients were from community hospital ERs and 72 were from the institution's own ER. In all, 115 (73%) patients were intubated prior to ICU admission and 42 (27%) patients were intubated after PICU admission. Of patients who received mechanical ventilation for status asthmaticus and were intubated prior to PICU admission, a greater proportion were intubated at community hospital ERs than in the institutions' own ERs. Eighty-five percent of the patients from community hospital ERs were intubated prior to PICU admission as opposed to 60% from institution's own ERs (P = .0004). However, median duration of intubation and PICU stay from community hospital ERs was significantly shorter than from the hospitals' own ERs (25 vs 42 hours P = .011; 57 vs 98 hours P = .0013, respectively). Logistic regression analysis revealed that after controlling for the effects of age, race, gender, and a revised version of the Paediatric Index of Mortality score of patients who were admitted for status asthmaticus and required mechanical ventilations, patients treated in community hospital ERs represented a greater proportion of preadmission intubation. The odds ratio for preadmission intubation was 5.1 if the patients arrived from community hospital ERs (95% confidence interval 1.91-13.6). CONCLUSION: PATIENTS with status asthmaticus are more likely to be intubated when they are admitted from community hospital emergency rooms, although the duration of intubation and PICU stay is shorter.
