Abstract
We report the radio and high-energy properties of a new outburst from the radio-loud magnetar 1E 1547.0−5408. Following the detection of a short burst from the source with Swift-BAT on 2022 ...April 7, observations by NICER detected an increased flux peaking at (6.0 ± 0.4) × 10
−11
erg s
−1
cm
−2
in the soft X-ray band, falling to a baseline level of 1.7 × 10
−11
erg s
−1
cm
−2
over a 17 day period. Joint spectroscopic measurements by NICER and NuSTAR indicated no change in the hard nonthermal tail despite the prominent increase in soft X-rays. Observations at radio wavelengths with Murriyang, the 64 m Parkes radio telescope, revealed that the persistent radio emission from the magnetar disappeared at least 22 days prior to the initial Swift-BAT detection and was redetected two weeks later. Such behavior is unprecedented in a radio-loud magnetar, and may point to an unnoticed slow rise in the high-energy activity prior to the detected short bursts. Finally, our combined radio and X-ray timing revealed the outburst coincided with a spin-up glitch, where the spin frequency and spin-down rate increased by 0.2 ± 0.1
μ
Hz and (−2.4 ± 0.1) × 10
−12
s
−2
, respectively. A linear increase in the spin-down rate of (−2.0 ± 0.1) × 10
−19
s
−3
was also observed over 147 days of postoutburst timing. Our results suggest that the outburst may have been associated with a reconfiguration of the quasi-polar field lines, likely signaling a changing twist, accompanied by spatially broader heating of the surface and a brief quenching of the radio signal, yet without any measurable impact on the hard X-ray properties.
BACKGROUND:The emergence of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) has altered the management of pediatric musculoskeletal infections. Yet, institution-to-institution ...differences in MRSA virulence may exist, suggesting a need to carefully examine local epidemiological characteristics. The purpose of this study was to compare MRSA and methicillin-sensitive S. aureus (MSSA) musculoskeletal infections with respect to prevalence and complexity of clinical care over the past decade at a single children’s hospital.
METHODS:We retrospectively reviewed a series of patients presenting to The Children’s Hospital of Philadelphia with a diagnosis of osteomyelitis, septic arthritis, or both over a 10-year period. Inclusion criteria were S. aureus (SA) infections proven by positive culture of blood, bone, or joint aspirate. Exclusion criteria were non-SA infectious etiologies. Hospital-acquired infections were also not included to exclusively evaluate acute, community-acquired cases. Data related to hospital course, laboratory values, and number of surgical interventions were collected and compared between MRSA and MSSA cohorts.
RESULTS:In our series of pediatric patients, we identified 148 cases of acute, community-acquired musculoskeletal SA infections (MRSA, n=37 and MSSA, n=111). The prevalence of MRSA musculoskeletal infections increased from 11.8% in 2001 to 2002 to 34.8% in 2009 to 2010. Compared with MSSA, MRSA infections resulted in higher presenting C-reactive protein levels (10.4 vs. 7.8 mg/L, P=0.04), longer inpatient stays (10 vs. 5 d, P<0.01), multiple surgical procedures (n>1) (38% vs. 14%, P<0.01), increased sequelae (27% vs. 6%, P<0.01), and more frequent admissions to the intensive care unit (16% vs. 3%, P<0.01).
CONCLUSIONS:At our institution over the past decade, we found an approximate 3-fold rise in community-acquired pediatric MRSA musculoskeletal infections accompanied by an elevated risk for complications during inpatient management. Awareness of the epidemiological trends of MRSA within the local community may guide parental counseling and facilitate timely and accurate clinical diagnosis and treatment.
LEVEL OF EVIDENCE:Level II—prognostic retrospective study.
BACKGROUND:Concerns about radiation exposure have created a controversy over long-term radiographic follow-up of developmental dysplasia of the hip (DDH) in infants who achieve normal clinical and ...ultrasonographic examinations. The purpose of this study was to assess the importance of continued radiographic monitoring by contrasting the incidence of residual radiographic dysplasia to the risks of radiation exposure.
METHODS:We reviewed a consecutive series of infants with idiopathic DDH presenting to our institution over 4 years. Infants with “normalized DDH” had achieved a stable clinical examination with an ultrasound revealing no signs of either hip instability or acetabular dysplasia. We excluded infants with persistently abnormal ultrasonographic indices, clinical examinations, or both by 6 months of age, including those requiring surgical reduction. Anteroposterior pelvic radiographs at approximately 6 and 12 months of age were then evaluated for evidence of residual radiographic acetabular dysplasia. Radiation effective dose was calculated using PCXMC software.
RESULTS:We identified 115 infants with DDH who had achieved both normal ultrasonographic and clinical examinations at 3.1±1.1 months of age. At the age of 6.6±0.8 months, 17% of all infants demonstrated radiographic signs of acetabular dysplasia. Of infants left untreated (n=106), 33% had dysplasia on subsequent radiographs at 12.5±1.2 months of age. No significant differences were evident in either the 6- or 12-month rates of dysplasia between infants successfully treated with a Pavlik harness and infants normalizing without treatment but with a history of risk factors (P>0.05). The radiation effective dose was <0.01 mSv for the combined 6- and 12-month single-view anteroposterior radiographs of the pelvis.
CONCLUSIONS:The notable incidences of radiographic dysplasia after previous DDH normalization in our study cohort appear to outweigh the risks of radiation exposure. Our findings may warrant radiographic follow-up in this population of infants through at least walking age to allow timely diagnosis and early intervention of residual acetabular dysplasia.
LEVEL OF EVIDENCE:Level IV—retrospective case series.
BACKGROUND:Breech position subjects the fetal hip to abnormal mechanical forces. However, unlike genetic or tissue factors linked to developmental dysplasia of the hip (DDH), the causative effect of ...the breech position ends when the infant is born. The purpose of this study was to evaluate the rate of spontaneous stabilization in mildly unstable hips of breech-presenting infants compared with similarly lax hips in infants with a genetic or tissue-related cause of DDH.
METHODS:We studied a consecutive series of infants presenting to our institution at 8 weeks of age or younger with DDH from January 2008 to January 2012. Infants with increased hip laxity on dynamic ultrasound examination but without frank instability on clinical provocation maneuvers and no history of prior treatment were evaluated. The endpoint was spontaneous stabilization of ultrasound-detected instability, or intervention due to persistent instability on follow-up dynamic ultrasound. A logistic regression model using backward likelihood ratio method was used to analyze predictors of spontaneous stabilization.
RESULTS:We identified 122 hips in 79 infants with instability on dynamic ultrasound evaluation but with stable clinical examinations. Spontaneous stabilization of sonographic instability occurred in 90 hips (74%) at a mean age of 9 weeks (range, 4 to 18 wk). Breech hips more frequently spontaneously stabilized compared with nonbreech hips (80% vs. 66%). Regression analysis determined that breech presentation was a strong independent predictor for spontaneous hip stabilization (odds ratio, 3.72; 95% confidence interval, 1.45-9.60; P=0.006). Sex, family history, intrauterine positioning syndromes, side involved, bilateralism, and grade of sonographic hip instability were not independently predictive of spontaneous hip stabilization.
CONCLUSIONS:DDH infants with a history of breech presentation are 3.72 times more likely to experience spontaneous resolution of mild hip instability compared with nonbreech infants. Awareness that breech presentation is a strong independent predictor of spontaneous laxity resolution can guide parental counseling and early care of DDH.
LEVEL OF EVIDENCE:Level II, prognostic retrospective study.
We present the third data release from the Parkes Pulsar Timing Array (PPTA) project. The release contains observations of 32 pulsars obtained using the 64-m Parkes ‘Murriyang’ radio telescope. The ...data span is up to 18 yr with a typical cadence of 3 weeks. This data release is formed by combining an updated version of our second data release with
$\sim$
3 yr of more recent data primarily obtained using an ultra-wide-bandwidth receiver system that operates between 704 and 4032 MHz. We provide calibrated pulse profiles, flux density dynamic spectra, pulse times of arrival, and initial pulsar timing models. We describe methods for processing such wide-bandwidth observations and compare this data release with our previous release.
The Bering Land Bridge (BLB) last connected Eurasia and North America during the Late Pleistocene. Although the BLB would have enabled transfers of terrestrial biota in both directions, it also acted ...as an ecological filter whose permeability varied considerably over time. Here we explore the possible impacts of this ecological corridor on genetic diversity within, and connectivity among, populations of a once wide‐ranging group, the caballine horses (Equus spp.). Using a panel of 187 mitochondrial and eight nuclear genomes recovered from present‐day and extinct caballine horses sampled across the Holarctic, we found that Eurasian horse populations initially diverged from those in North America, their ancestral continent, around 1.0–0.8 million years ago. Subsequent to this split our mitochondrial DNA analysis identified two bidirectional long‐range dispersals across the BLB ~875–625 and ~200–50 thousand years ago, during the Middle and Late Pleistocene. Whole genome analysis indicated low levels of gene flow between North American and Eurasian horse populations, which probably occurred as a result of these inferred dispersals. Nonetheless, mitochondrial and nuclear diversity of caballine horse populations retained strong phylogeographical structuring. Our results suggest that barriers to gene flow, currently unidentified but possibly related to habitat distribution across Beringia or ongoing evolutionary divergence, played an important role in shaping the early genetic history of caballine horses, including the ancestors of living horses within Equus ferus.
On 14 January 2004 President George Bush announced his vision for space exploration, to include a human return to the Moon. He argued that, with a moderate increase in NASA's annual expenditure, such ...a return was possible. This paper is an exploration of how the President's space initiative can be realised on an international co-operative basis along similar lines to those already existing with the international space station (ISS). By abandoning the concept of a lunar landing as the major goal of a lunar programme, the initiative is made feasible. The three-stage plan here presented meshes with the currently evolving plans for the US space initiative to provide a realistic, affordable and sustainable strategy for manned lunar exploration. It represents a significant opportunity for the USA to unite and lead the world on this grand, civilisation defining adventure.
We have observed the Vela pulsar for 1 year using a Phased Array Feed (PAF) receiver on the 12-m antenna of the Parkes Test-Bed Facility (PTF). These observations have allowed us to investigate the ...stability of the PAF beam weights over time, to demonstrate that pulsars can be timed over long periods using PAF technology and to detect and study the most recent glitch event that occurred on 12 December 2016. The beam weights are shown to be stable to 1% on time scales on the order of three weeks.
We describe the approach for the estimation of the atmospheric state, e.g., temperature, water, ozone, from calibrated, spectral radiances measured from the Tropospheric Emission Spectrometer (TES) ...onboard the Aura spacecraft. The methodology is based on the maximum a posteriori estimate, which mathematically requires the minimization of the difference between observed spectral radiances and a nonlinear model of radiative transfer of the atmospheric state subject to the constraint that the estimated state must be consistent with an a priori probability distribution for that state. The minimization techniques employed here are based on the trust-region Levenberg-Marquardt algorithm. An analysis of the errors for this estimate include smoothing, random, spectroscopic, "cross-state", representation, and systematic errors. In addition, several metrics and diagnostics are introduced that assess the resolution, quality, and statistical significance of the retrievals. We illustrate this methodology for the retrieval of atmospheric and surface temperature, water vapor, and ozone over the Gulf of Mexico on November 3, 2004.
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