Line Structure in the Spectrum of FU Orionis

New high-resolution spectra of FU Ori, obtained with the HIRES spectrograph at the Keck I telescope in 2003-2006, make it possible to compare the optical line profiles with those predicted by the self-luminous accretion disk model. A dependence of line width on excitation potential and on wavelength, expected for a Keplerian disk, is definitely not present in the optical region, nor is the line duplicity due to velocity splitting. The absorption lines observed in the optical region of FU Ori must originate in or near the central object, and here their profiles are shown to be those expected of a rigidly rotating object. They can be fitted by a rapidly rotating (v sin i = 70 km/s) high-luminosity G-type star having a large dark polar spot, with axis inclined toward the line of sight. Over these years, the radial velocity of FU Ori has remained constant to within +/-0.3 km/s, so there is no indication that the star is a spectroscopic binary. These results apply to the optical region ($\lambda< 8800$ \AA); more distant, cooler regions of the disk contribute in the infrared.Comment: 14 pages, 11 figures, accepted by A

The dynamic nature of refugee children's resilience: a cohort study of Syrian refugees in Lebanon.

AIMS: Children's responses to war and displacement are varied; many struggle, while others appear resilient. However, research into these outcomes disproportionately focuses on cross-sectional data in high-income countries. We aimed to (1) investigate change in resilience across two timepoints in a highly vulnerable sample of Syrian refugee children in Lebanon, and (2) explore predictors of their mental health problems across time. METHODS: In total, 982 Syrian child-caregiver dyads living in refugee settlements in Lebanon completed questionnaires via interview at baseline and follow-up one year later. We categorised children into groups based on their risk for mental health problems across both timepoints (stable high risk/SHR, deteriorating, improving, stable low risk) according to locally validated cut-offs on measures of post-traumatic stress disorder (PTSD), depression and behavioural problems. Analyses of covariance identified how the groups differed on a range of individual and socio-environmental predictors, followed up by cross-lagged panel models (CLPMs) to investigate the directionality of the relationships between significantly related predictors and symptoms. RESULTS: The sample showed a meaningful amount of change in mental health symptoms from baseline to follow-up. Over half (56.3%) of children met SHR criteria and 10.3% deteriorated over time, but almost one-quarter (24.2%) showed meaningful improvement, and 9.2% were consistently at low risk for mental health problems at both timepoints. Several predictors differentiated the groups, particularly social measures. According to CLPMs, maternal acceptance (β = -0.07) predicted child mental health symptoms over time. Self-esteem (β = -0.08), maternal psychological control (β = 0.10), child maltreatment (β = 0.09) and caregiver depression (β = 0.08) predicted child symptoms and vice versa (βse = -0.11, βb = 0.07, βmpc = 0.08, βcm = 0.1, βcd = 0.11). Finally, child symptoms predicted loneliness (β = 0.12), bullying (β = 0.07), perceived social support (β = -0.12), parent-child conflict (β = 0.13), caregiver PTSD (β = 0.07), caregiver anxiety (β = 0.08) and the perceived refugee environment (β = -0.09). CONCLUSIONS: Our results show risk and resilience are dynamic, and the family environment plays a key role in children's response to war and displacement. Conversely, children also have a significant impact on the family environment and caregiver's own mental health. Interventions to promote resilience in refugee children should therefore consider family-wide mechanisms

Near-infrared spectroscopy of EX Lupi in outburst

EX Lup is the prototype of the EXor class of young eruptive stars: objects showing repetitive brightenings due to increased accretion from the circumstellar disk to the star. In this paper, we report on medium-resolution near-infrared spectroscopy of EX\,Lup taken during its extreme outburst in 2008, as well as numerical modeling with the aim of determining the physical conditions around the star. We detect emission lines from atomic hydrogen, helium, and metals, as well as first overtone bandhead emission from carbon monoxide. Our results indicate that the emission lines are originating from gas located in a dust-free region within ~ 0.2 AU of the star. The profile of the CO bandhead indicates that the CO gas has a temperature of 2500 K, and is located in the inner edge of the disk or in the outer parts of funnel flows. The atomic metals are probably co-located with the CO. Some metallic lines are fluorescently excited, suggesting direct exposure to ultraviolet photons. The Brackett series indicates emission from hot (10000 K) and optically thin gas. The hydrogen lines display a strong spectro-astrometric signal, suggesting that the hydrogen emission is probably not coming from an equatorial boundary layer; a funnel flow or disk wind origin is more likely. This picture is broadly consistent with the standard magnetospheric accretion model usually assumed for normally accreting T Tauri stars. Our results also set constraints on the eruption mechanism, supporting a model where material piles up around the corotation radius and episodically falls onto the star.Comment: 12 pages, 8 figures, 1 table, accepted for publication in Ap

The boundary layer of VW Hyi in quiescence

In this letter, we suggest that the missing boundary layer luminosity of dwarf novae in quiescence is released mainly in the ultraviolet (UV) as the second component commonly identified in the far ultraviolet (FUV) as the "accretion belt". We present the well-studied SU UMa-type system VW Hyi in detail as a prototype for such a scenario. We consider detailed multiwavelength observations and in particular the recent FUSE observations of VW Hyi which confirm the presence of a second component (the "accretion belt") in the FUV spectrum of VW Hyi in quiescence. The temperature (50,000K) and rotational velocity (> 3,000km/s) of this second FUV component are entirely consistent with the optically thick region (tau = 1) located just at the outer edge of optically thin boundary layer in the simulations of Popham (1999). This second component contributes 20% of the FUV flux, therefore implying a boundary layer luminosity: $L_{BL} = 2 \times (0.2 \times L_{UV} + L_{X-ray}) = 0.6 \times L_{disc}$, while the theory (Klu\'zniak 1987) predicts, for the rotation rate of VW Hyi's WD, $L_{BL} \approx 0.77 L_{disc}$. The remaining accretion energy ($<0.1 L_{acc}$) is apparently advected into the star as expected for optically thin advection dominated boundary layers. This scenario is consistent with the recent simultaneous X-ray and UV observations of VW Hyi by (Pandel, C\'ordova & Howell 2003), from which we deduced here that the alpha viscosity parameter in the boundary layer region must be as small as $\alpha \approx 0.004$.Comment: 4 page

Causal Viscosity in Accretion Disc Boundary Layers

The structure of the boundary layer region between the disc and a comparatively slowly rotating star is studied using a causal prescription for viscosity. The vertically integrated viscous stress relaxes towards its equilibrium value on a relaxation timescale $\tau$, which naturally yields a finite speed of propagation for viscous information. For a standard alpha prescription with alpha in the range 0.1-0.01, and ratio of viscous speed to sound speed in the range 0.02-0.5, details in the boundary layer are strongly affected by the causality constraint. We study both steady state polytropic models and time dependent models, taking into account energy dissipation and transport. Steady state solutions are always subviscous with a variety of $\Omega$ profiles which may exhibit near discontinuities. For alpha =0.01 and small viscous speeds, the boundary layer adjusted to a near steady state. A long wavelength oscillation generated by viscous overstability could be seen at times near the outer boundary. Being confined there, the boundary layer remained almost stationary. However, for alpha =0.1 and large viscous speeds, short wavelength disturbances were seen throughout which could significantly affect the power output in the boundary layer. This could be potentially important in producing time dependent behaviour in accreting systems such as CVs and protostars.Comment: 10 LateX pages, requires lamuphys.sty and psfig.sty, 3 figures included, to appear in the Proceedings of the EARA Workshop on Accretion Disks (Garching, Oct. 96), Lecture Notes in Physic

Exploring the spreading layer of GX 9+9 using RXTE and INTEGRAL

We have fitted ~200 RXTE and INTEGRAL spectra of the neutron star LMXB GX 9+9 from 2002-2007 with a model consisting of a disc blackbody and another blackbody representing the spreading layer (SL), i.e. an extended accretion zone on the NS surface as opposed to the more traditional disc-like boundary layer. Contrary to theory, the SL temperature was seen to increase towards low SL luminosities, while the approximate angular extent had a nearly linear luminosity dependency. Comptonization was not required to adequately fit these spectra. Together with the ~70 degree upper bound of inclination implied by the lack of eclipses, the best-fitting normalization of the accretion disc blackbody component implies a distance of ~10 kpc, instead of the usually quoted 5 kpc.Comment: 14 pages, 10 figures, accepted for publication in MNRA

Cohort profile: biological pathways of risk and resilience in Syrian refugee children (BIOPATH)

The BIOPATH cohort was established to explore the interplay of psychosocial and biological factors in the development of resilience and mental health problems in Syrian refugee children. Based in Lebanon, a middle-income country significantly impacted by the refugee crisis, it is the first such cohort of refugees in the Middle East. Families were recruited from informal tented settlements in the Beqaa region using purposive cluster sampling. At baseline (October 2017–January 2018), N = 3188 individuals participated [n = 1594 child–caregiver dyads; child gender, 52.6% female; mean (SD) age = 11.44 (2.44) years, range = 6–19]. Re-participation rate at 1-year follow-up was 62.8%. Individual interviews were conducted with children and primary caregivers and biological samples collected from children. Measures include: (1) children’s well-being and mental health problems (using tools validated against clinical interviews in a subsample of the cohort); (2) psychosocial risk and protective factors at the level of the individual (e.g. coping strategies), family (e.g. parent–child relationship), community (e.g. collective efficacy), and wider context (e.g. services); (3) saliva samples for genetic and epigenetic (methylation) analyses; (4) hair samples to measure cortisol, dehydroepiandrosterone (DHEA) and testosterone. This cohort profile provides details about sampling and recruitment, data collection and measures, demographic data, attrition and potential bias, key findings on resilience and mental health problems in children and strengths and limitations of the cohort. Researchers interested in accessing data should contact Professor Michael Pluess at Queen Mary University of London, UK (e-mail: [email protected]). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00127-022-02228-8

Socioeconomic inequalities in the quality of life of older Europeans in different welfare regimes

Background: Whether socioeconomic inequalities in health and well-being persist into old age and are narrower in more generous welfare states is debated. We investigated the magnitude of socioeconomic inequality in the quality of life of Europeans in early old age and the influence of the welfare regime type on these relationships.&lt;p&gt;&lt;/p&gt; Methods: Data from individuals aged 50–75 years (n = 16 074) residing in 13 European countries were derived from Waves 2 and 3 of the Survey of Health, Ageing and Retirement in Europe. Slope indices of inequality (SIIs) were calculated for the association between socioeconomic position and CASP-12, a measure of positive quality of life. Multilevel linear regression was used to assess the overall relationship between socioeconomic position and quality of life, using interaction terms to investigate the influence of the type of welfare regime (Southern, Scandinavian, Post-communist or Bismarckian).&lt;p&gt;&lt;/p&gt; Results: Socioeconomic inequalities in quality of life were narrowest in the Scandinavian and Bismarckian regimes, and were largest by measures of current wealth. Compared with the Scandinavian welfare regime, where narrow inequalities in quality of life by education level were found in both men (SII = 0.02, 95% CI: −1.09 to 1.13) and women (SII = 1.11, 95% CI: 0.05–2.17), the difference in quality of life between the least and most educated was particularly wide in Southern and Post-communist regimes.&lt;p&gt;&lt;/p&gt; Conclusion: Individuals in more generous welfare regimes experienced higher levels of quality of life, as well as narrower socioeconomic inequalities in quality of life.&lt;p&gt;&lt;/p&gt

Advection-Dominated Accretion Model of Sagittarius A*: Evidence for a Black Hole at the Galactic Center

Sgr A* at the Galactic Center is a puzzling source. It has a mass M=(2.5+/-0.4) x 10^6 solar masses which makes it an excellent black hole candidate. Observations of stellar winds and other gas flows in its vicinity suggest a mass accretion rate approximately few x 10^{-6} solar masses per year. However, such an accretion rate would imply a luminosity > 10^{40} erg/s if the radiative efficiency is the usual 10 percent, whereas observations indicate a bolometric luminosity <10^{37} erg/s. The spectrum of Sgr A* is unusual, with emission extending over many decades of wavelength. We present a model of Sgr A* which is based on a two-temperature optically-thin advection-dominated accretion flow. The model is consistent with the estimated mass and accretion rate, and fits the observed fluxes in the cm/mm and X-ray bands as well as upper limits in the sub-mm and infrared bands; the fit is less good in the radio below 86 GHz and in gamma-rays above 100 MeV. The very low luminosity of Sgr A* is explained naturally in the model by means of advection. Most of the viscously dissipated energy is advected into the central mass by the accreting gas, and therefore the radiative efficiency is extremely low, approximately 5 x 10^{-6}. A critical element of the model is the presence of an event horizon at the center which swallows the advected energy. The success of the model could thus be viewed as confirmation that Sgr A* is a black hole.Comment: 41 pages (Latex) including 6 Figures and 2 Tables. Final Revised Version changes to text, tables and figures. ApJ, 492, in pres

Raising standards in American schools: the case of No Child Left Behind

In January 2002, President George W Bush signed into law what is arguably the most important piece of US educational legislation for the past 35 years. For the first time, Public Law 107-110 links high stakes testing with strict accountability measures designed to ensure that, at least in schools that receive government funding, no child is left behind. The appropriately named No Child Left Behind Act (NCLB) links government funding to strict improvement policies for America’s public schools. Much of what is undertaken in NCLB is praiseworthy, the Act is essentially equitable for it ensures that schools pay due regard to the progress of those sections of the school population who have traditionally done less well in school, in particular, students from economically disadvantaged homes, as well as those from ethnic minority backgrounds and those who have limited proficiency to speak English. However, this seemingly salutatory aspect of the Act is also the one that has raised the most objections. This paper describes the key features of this important piece of legislation before outlining why it is that a seemingly equitable Act has produced so much consternation in US education circles. Through an exploration of school level data for the state of New Jersey, the paper considers the extent to which these concerns have been justified during the early days of No Child Left Behind