Cyclotron lines in X-ray pulsars as a probe of relativistic plasmas in superstrong magnetic fields

The systematic search for the presence of cyclotron lines in the spectra of accreting X-ray pulsars is being carried on with the BeppoSAX satellite since the beginning of the mission. These highly successful observations allowed the detection of cyclotron lines in many of the accreting X-ray pulsars observed. Some correlations between the different measured parameters were found. We present these correlations and discuss them in the framework of the current theoretical scenario for the X-ray emission from these sources.Comment: 5 pages, 2 figures, uses aipproc.sty, to appear in Proceeding of Fifth Compton Symposiu

The pulse phase-dependent spectrum of the anomalous X-ray pulsar 1RXS J170849-400910

We report on the results of a 50ks BeppoSAX observation of 1RXS J170849-400910, one of the five (plus a candidate) known anomalous X-ray pulsars. The BeppoSAX data are consistent with a power-law plus blackbody spectral decomposition, making 1RXS J170849-400910 the fourth source of this class for which such a spectral decomposition was found. The inferred power-law slope and blackbody temperature are Gamma~2.6 and kT_BB~0.46keV, respectively. We found significant energy-dependence of the pulse profile, a remarkable feature for an AXP. By using the power-law plus blackbody decomposition we detected a significant variation in at least one spectral parameter, the power-law photon index, as a function of the pulse phase. This is the first significant detection of spectral parameter variation in an AXP. The implications of these results are briefly discussed.Comment: 5 pages. Accepted for publication on ApJ Letters. emulateapj5.sty macro use

SARS-CoV-2 Omicron is an immune escape variant with an altered cell entry pathway

Vaccines based on the spike protein of SARS-CoV-2 are a cornerstone of the public health response to COVID-19. The emergence of hypermutated, increasingly transmissible variants of concern (VOCs) threaten this strategy. Omicron (B.1.1.529), the fifth VOC to be described, harbours multiple amino acid mutations in spike, half of which lie within the receptor-binding domain. Here we demonstrate substantial evasion of neutralization by Omicron BA.1 and BA.2 variants in vitro using sera from individuals vaccinated with ChAdOx1, BNT162b2 and mRNA-1273. These data were mirrored by a substantial reduction in real-world vaccine effectiveness that was partially restored by booster vaccination. The Omicron variants BA.1 and BA.2 did not induce cell syncytia in vitro and favoured a TMPRSS2-independent endosomal entry pathway, these phenotypes mapping to distinct regions of the spike protein. Impaired cell fusion was determined by the receptor-binding domain, while endosomal entry mapped to the S2 domain. Such marked changes in antigenicity and replicative biology may underlie the rapid global spread and altered pathogenicity of the Omicron variant

Transition in the X-ray light curve of the AM her system V834 Cen (E1405-451):1985 - 1986 EXOSAT observations

Accepted: The Astrophysical JournalConsiglio Nazionale delle Ricerche. Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Basic echocardiography competence program in intensive care units : a multinational survey of intensive care units accredited by the college of intensive care medicine

In 2014, basic critical care echocardiography (BCCE) competence became a mandatory requirement for trainees registered with the College of Intensive Care Medicine (CICM). To determine the proportion of CICM intensive care units (ICUs) that conduct a BCCE competence program and to learn about the barriers/challenges and successful strategies, we conducted a survey of intensivists working in ICUs accredited by CICM for basic/advanced training in Australia, New Zealand, Hong Kong, Singapore, Ireland and India. Following consultations with content experts and a trial phase to improve clarity and minimise ambiguity, an 11-point questionnaire survey was sent to one intensivist from every CICM-accredited ICU by several methods. Participation was voluntary. Consent was implied. No incentives were offered. Results are reported as numbers and percentages. Of the 104 ICUs surveyed, 99 (95.1%) responded, with 75 (75.8%) having no BCCE teaching whatsoever. In the remaining 24 (24.2%) ICUs, the teaching process was widely variable. Only 5/99 (5.1%) ICUs provided a structured BCCE competence program through which trainees performed and archived BCCE scans, maintained a logbook and underwent formative and summative assessments for credentialling. Six more ICUs provided formative assessment but relied on external bodies for competence assessment. Overall, 20/99 (20.2%) ICUs allowed trainees to perform unsupervised scans for clinical management, even if they were not BCCE competent. Nineteen intensivists perceived management errors due to misinterpretation of echocardiographic findings. Very few CICM-accredited ICUs offer a structured BCCE competence program. To fulfil the objective of universal BCCE competence, potential solutions are presented