X-ray reverberation in 1H0707-495 revisited

The narrow-line Seyfert 1 galaxy 1H0707-495 has previously been identified as showing time lags between flux variations in the soft- (0.3-1 keV) and medium-energy (1-4 keV) X-ray bands that oscillate between positive and negative values as a function of the frequency of the mode of variation. Here we measure and analyse the lags also between a harder X-ray band (4-7.5 keV) and the soft and medium bands, using existing XMM-Newton data, and demonstrate that the entire spectrum of lags, considering both the full energy range, 0.3-7.5 keV, and the full frequency range, 10^-5 < nu < 10^-2 Hz, are inconsistent with previous claims of arising as reverberation associated with the inner accretion disk. Instead we demonstrate that a simple reverberation model, in which scattering or reflection is present in all X-ray bands, explains the full set of lags without requiring any ad hoc explanation for the time lag sign changes. The range of time delays required to explain the observed lags extends up to about 1800 s in the hard band. The results are consistent with reverberation caused by scattering of X-rays passing through an absorbing medium whose opacity decreases with increasing energy and that partially-covers the source. A high covering factor of absorbing and scattering circumnuclear material is inferred.Comment: Accepted for publication in MNRA

Expanding the Family of Grassmannian Kernels: An Embedding Perspective

Modeling videos and image-sets as linear subspaces has proven beneficial for many visual recognition tasks. However, it also incurs challenges arising from the fact that linear subspaces do not obey Euclidean geometry, but lie on a special type of Riemannian manifolds known as Grassmannian. To leverage the techniques developed for Euclidean spaces (e.g, support vector machines) with subspaces, several recent studies have proposed to embed the Grassmannian into a Hilbert space by making use of a positive definite kernel. Unfortunately, only two Grassmannian kernels are known, none of which -as we will show- is universal, which limits their ability to approximate a target function arbitrarily well. Here, we introduce several positive definite Grassmannian kernels, including universal ones, and demonstrate their superiority over previously-known kernels in various tasks, such as classification, clustering, sparse coding and hashing

Medical cannabis: A needs analysis for people with epilepsy

Background and purpose: Medical cannabis may be effective treatment for refractory epilepsy. It is timely to seek users’ and potential users’ opinions in regard to its place in the management of epilepsy. Materials and methods: An online survey was administered to members of an epilepsy support organisation in Western Australia. Experience with cannabis for management of epilepsy was explored, along with desire to trial a particular pharmaceutical formulation(s). Results: People with epilepsy (33/71) and carers (38/71) participated. Fifty-four participants indicated no experience with medical cannabis, although 35, mainly with inadequate response to prescription medicines, were willing to ask for a prescription. Concerns included difficulty accessing cannabis and high cost of this treatment. Tablets/capsules was the most acceptable dosage form for development. Conclusion: These findings suggest wide interest in trialling medical cannabis in individual cases of refractory epilepsy, despite the developing body of literature and some concerns about cost and procurement

Multi-dimensional modelling of X-ray spectra for AGN accretion-disk outflows III: application to a hydrodynamical simulation

We perform multi-dimensional radiative transfer simulations to compute spectra for a hydrodynamical simulation of a line-driven accretion disk wind from an active galactic nucleus. The synthetic spectra confirm expectations from parameterized models that a disk wind can imprint a wide variety of spectroscopic signatures including narrow absorption lines, broad emission lines and a Compton hump. The formation of these features is complex with contributions originating from many of the different structures present in the hydrodynamical simulation. In particular, spectral features are shaped both by gas in a successfully launched outflow and in complex flows where material is lifted out of the disk plane but ultimately falls back. We also confirm that the strong Fe Kalpha line can develop a weak, red-skewed line wing as a result of Compton scattering in the outflow. In addition, we demonstrate that X-ray radiation scattered and reprocessed in the flow has a pivotal part in both the spectrum formation and determining the ionization conditions in the wind. We find that scattered radiation is rather effective in ionizing gas which is shielded from direct irradiation from the central source. This effect likely makes the successful launching of a massive disk wind somewhat more challenging and should be considered in future wind simulations.Comment: 14 pages, 8 figures. Accepted for publication by MNRA

Social comparison and life satisfaction in social media: The role of mattering and state self-esteem

The overarching aim of this study is to explain how comparing self to others in social media might predict one’s sense of life satisfaction. In order to achieve that, we test the hypothesis that mattering and state self-esteem play a serial mediation that explains the link between social comparison in social media and life satisfaction. One hundred and forty-seven participants’ ages between 18 to 35 were recruited to participate in this research and were asked to fill up the Iowa-Netherlands Comparison Orientation Measure, General Mattering Scale, State Self-Esteem Scale and Riverside Life Satisfaction Scale questionnaires. Bias-free Bootstrap Method with 5000 sample has been conducted to analyze the relationship among the variables, and the results suggested that the overall model of the predictor significantly contributed to life satisfaction. Nevertheless, because social comparison did not predict the sense of mattering, serial mediation did not occur as per hypothesized. Our supplementary analyses indicated that state self-esteem fully mediated the contribution of mattering on life satisfaction. Implication, limitation and suggestions are discussed at the end of the paper

Using Second Life for health professional learning: informing multidisciplinary understanding

Background: The pressures of working in contemporary health care environments can result in health professionals becoming focused on their own domain. This focus, while understandable, diminishes the ability to provide holistic care for patients and clients. This multidisciplinary project sought to introduce post graduate students to the work of three other disciplines and provided them with an opportunity to develop their communication and history taking skills in the virtual world of Second Life. The participating disciplines included: Midwifery, Mental Health, Medical Radiations and Chiropractic

Type Ia supernovae from exploding oxygen-neon white dwarfs

The progenitor problem of Type Ia supernovae (SNe Ia) is still unsolved. Most of these events are thought to be explosions of carbon-oxygen (CO) white dwarfs (WDs), but for many of the explosion scenarios, particularly those involving the externally triggered detonation of a sub-Chandrasekhar mass WD (sub-M Ch WD), there is also a possibility of having an oxygen-neon (ONe) WD as progenitor. We simulate detonations of ONe WDs and calculate synthetic observables from these models. The results are compared with detonations in CO WDs of similar mass and observational data of SNe Ia. We perform hydrodynamic explosion simulations of detonations in initially hydrostatic ONe WDs for a range of masses below the Chandrasekhar mass (M Ch), followed by detailed nucleosynthetic postprocessing with a 384-isotope nuclear reaction network. The results are used to calculate synthetic spectra and light curves, which are then compared with observations of SNe Ia. We also perform binary evolution calculations to determine the number of SNe Ia involving ONe WDs relative to the number of other promising progenitor channels. The ejecta structures of our simulated detonations in sub-M Ch ONe WDs are similar to those from CO WDs. There are, however, small systematic deviations in the mass fractions and the ejecta velocities. These lead to spectral features that are systematically less blueshifted. Nevertheless, the synthetic observables of our ONe WD explosions are similar to those obtained from CO models. Our binary evolution calculations show that a significant fraction (3-10%) of potential progenitor systems should contain an ONe WD. The comparison of our ONe models with our CO models of comparable mass (1.2 Msun) shows that the less blueshifted spectral features fit the observations better, although they are too bright for normal SNe Ia.Comment: 6 pages, 5 figure

Authors' reply re: Laparoscopic ablation or excision with helium thermal coagulator versus electrodiathermy for the treatment of mild-to-moderate endometriosis: randomised controlled trial.

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