Monitoring RXTE Observations of Markarian 348: the origin of the column density variations

We analyze 37 RXTE observations of the type 2 Seyfert galaxy Mrk348 obtained during a period of 14 months. We confirm the spectral variability previous reported by Smith et al., in the sense that thecolumn density decreases by a factor of ~3 as the count rate increases. Column density variations could possibly originate either due to the random drift of clouds within the absorption screen, or due to photoionization processes. Our modeling of the observed variations implies that the first scenario is more likely. These clouds should lie in a distance of >2 light years from the source, having a diameter of a few light days and a density of >10^7 cm^(-3), hence probably residing outside the Broad Line Region.Comment: 6 pages, 3 figures, to appear in MNRA

Understanding novice teachers’ perspectives on China’s sexuality education: a study based on the national pre-service teacher education programme

Good quality sexuality education is crucial for promoting young people’s sexual health and wellbeing. Teachers, as trusted resources of knowledge and skills, play a critical role in supporting young people’s sexual wellbeing. This study set out to investigate Chinese novice teachers’ perspectives on sexuality education. Interviews were conducted with 30 novice teachers who had graduated from a national pre-service teacher education programme in China. Results were analysed from a gender perspective. This study identified three specific capabilities teachers valued regarding delivering sexuality education in the classroom. A gender difference in teachers’ perceptions of the three capabilities was found. Additionally, four main constraints limited teachers to deliver sexuality education, and the interplay between these constraints and gender and broader sociocultural factors, is discussed. Results suggest that policy steps need to be taken in the education sector to reorient the current examination-dominated culture. In addition, an eco-system which engaged parents, students and the wider community should be built at school level. Meanwhile, teacher education programs need to shift attention to building teachers’ cross-curricular competences. Finally, a gender-sensitive approach is needed to address the influence of gender differences on teachers’ classroom practices

XMM-Newton Observation of the Black Hole Microquasar GRS 1758-258

The XMM-Newton X-ray observatory pointed the galactic black hole candidate and microquasar GRS 1758-258 in September 2000 for about 10 ks during a program devoted to the scan of the Galactic Center regions. Preliminary results from EPIC MOS camera data are presented here. The data indicate that the source underwent a state transition from its standard low-hard state to an intermediate state. For the first time in this source the ultra-soft component of the accretion disk, which black hole binaries display in intermediate or high-soft states, was clearly detected and measured thanks to the high spectral capabilities of XMM-Newton.Comment: To appear in the Proc. of the Gamma-Ray Astrophysics 2001 Symposium, 4-6 April 2001, Baltimore, Maryland, U.S.A.. American Institute of Physics (AIP) series: 5 pages, 6 PS figures, latex, uses aipproc.cls aipproc.st

Classroom dialogue and digital technologies: A scoping review

AbstractThis article presents a systematic scoping review of the literature focusing on interactions between classroom dialogue and digital technology. The first review of its type in this area, it both maps extant research and, through a process of thematic synthesis, investigates the role of technology in supporting classroom dialogue. In total, 72 studies (published 2000–2016) are analysed to establish the characteristics of existing evidence and to identify themes. The central intention is to enable researchers and others to access an extensive base of studies, thematically analysed, when developing insights and interpretations in a rapidly changing field of study. The discussion illustrates the interconnectedness of key themes, placing the studies in a methodological and theoretical context and examining challenges for the future.</jats:p

X-ray Spectroscopy of Candidate Ultracompact X-ray Binaries

We present high-resolution spectroscopy of the neutron star/low-mass X-ray binaries (LMXBs) 4U 1850-087 and 4U 0513-40 as part of our continuing study of known and candidate ultracompact binaries. The LMXB 4U 1850-087 is one of four systems in which we had previously inferred an unusual Ne/O ratio in the absorption along the line of sight, most likely from material local to the binaries. However, our recent Chandra X-ray Observatory LETGS spectrum of 4U 1850-087 finds a Ne/O ratio by number of 0.22+/-0.05, smaller than previously measured and consistent with the expected interstellar value. We propose that variations in the Ne/O ratio due to source variability, as previously observed in these sources, can explain the difference between the low- and high-resolution spectral results for 4U 1850-087. Our XMM-Newton RGS observation of 4U 0513-40 also shows no unusual abundance ratios in the absorption along the line of sight. We also present spectral results from a third candidate ultracompact binary, 4U 1822-000, whose spectrum is well fit by an absorbed power-law + blackbody model with absorption consistent with the expected interstellar value. Finally, we present the non-detection of a fourth candidate ultracompact binary, 4U 1905+000, with an upper limit on the source luminosity of < 1 x 10^{32} erg s^{-1}. Using archival data, we show that the source has entered an extended quiescent state.Comment: 8 pages, 3 figures, accepted for publication to the Astrophysical Journa

Variable X-ray Absorption in the Seyfert 2 Galaxy Mrk 348

We present RXTE monitoring observations of the Seyfert 2 galaxy Mrk 348 spanning a 6 month period. The time-averaged spectrum in the 3-20 keV band shows many features characteristic of a Compton-thin Seyfert 2 galaxy, namely a hard underlying power-law continuum (photon index = 1.8) with heavy soft X-ray absorption (N_h ~ 10^23 cm^-2) plus measureable iron line emission (equivalent width ~ 100 eV) and, at high energy, evidence for a reflection component (R < 1). During the first half of the monitoring period the X-ray continuum flux from Mrk 348 remained relatively steady. However this was followed by a significant brightening of the source (by roughly a factor of 4) with the fastest change corresponding to a doubling of its X-ray flux on a timescale of about 20 days. The flux increase was accompanied by a marked softening of X-ray spectrum most likely attributable to a factor 3 decline in the intrinsic line-of-sight column density. In contrast the iron line and the reflection components showed no evidence of variability. These observations suggest a scenario in which the central X-ray source is surrounded by a patchy distribution of absorbing material located within about a light-week of the nucleus of Mrk 348. The random movement of individual clouds within the absorbing screen, across our line of sight, produces substantial temporal variations in the measured column density on timescales of weeks to months and gives rise to the observed X-ray spectral variability. However, as viewed from the nucleus the global coverage and typical thickness of the cloud layer remains relatively constant.Comment: 19 pages, 3 figures Accepted for publication in the Astrophysical Journa