The type Iax supernova, SN 2015H: A white dwarf deflagration candidate

We present results based on observations of SN 2015H which belongs to the small group of objects similar to SN 2002cx, otherwise known as type Iax supernovae. The availability of deep pre-explosion imaging allowed us to place tight constraints on the explosion epoch. Our observational campaign began approximately one day post-explosion, and extended over a period of about 150 days post maximum light, making it one of the best observed objects of this class to date. We find a peak magnitude of M_r = -17.27± 0.07, and a (Δm₁₅)_r = 0.69 ± 0.04. Comparing our observations to synthetic spectra generated from simulations of deflagrations of Chandrasekhar mass carbon-oxygen white dwarfs, we find reasonable agreement with models of weak deflagrations that result in the ejection of ∼0.2 M_⊙ of material containing ∼0.07 M_⊙ of ⁵⁶Ni. The model light curve however, evolves more rapidly than observations, suggesting that a higher ejecta mass is to be favoured. Nevertheless, empirical modelling of the pseudo-bolometric light curve suggests that ≲ 0.6 M_⊙ of material was ejected, implying that the white dwarf is not completely disrupted, and that a bound remnant is a likely outcome.

A Simultaneous Equation Approach to Estimating HIV Prevalence with Non-Ignorable Missing Responses

Estimates of HIV prevalence are important for policy in order to establish the health status of a country's population and to evaluate the effectiveness of population-based interventions and campaigns. However, participation rates in testing for surveillance conducted as part of household surveys, on which many of these estimates are based, can be low. HIV positive individuals may be less likely to participate because they fear disclosure, in which case estimates obtained using conventional approaches to deal with missing data, such as imputation-based methods, will be biased. We develop a Heckman-type simultaneous equation approach which accounts for non-ignorable selection, but unlike previous implementations, allows for spatial dependence and does not impose a homogeneous selection process on all respondents. In addition, our framework addresses the issue of separation, where for instance some factors are severely unbalanced and highly predictive of the response, which would ordinarily prevent model convergence. Estimation is carried out within a penalized likelihood framework where smoothing is achieved using a parametrization of the smoothing criterion which makes estimation more stable and efficient. We provide the software for straightforward implementation of the proposed approach, and apply our methodology to estimating national and sub-national HIV prevalence in Swaziland, Zimbabwe and Zambia.

Balancing Rights in Religious Education through Collaboration and Dialogue

While the right of parents to educate their children in their religious or philosophical conviction is recognised in Human Rights instruments (e.g. CoE 1952, protocol 1), educators must also attend to the right of a child to autonomy (UN 1989, Article 12.1) and the right of liberal democratic states to reproduce values of equity and freedom. This paper argues that certain forms of inter-religious dialogue and/or inter-religious collaborative learning can assist educators in balancing these rights where religion has significant influence and power over the management of schools and/or the curriculum. It is argued that in addition to the learning benefits which may result, the use of collaboration and dialogue goes some way in addressing three philosophical criticisms of religious education: first that religiously separate and religiously based education pays insufficient attention to the rights of children and, secondly, is likely to contribute to social fragmentation; and third, pupils will lack the skills to overcome prejudice or intolerance where they have no experience of others as a result of separate schooling or from a religiously narrow curriculum, and the latter may in fact support intolerant views. A rationale is developed that asserts the value of collaboration or dialogue as a pedagogical strategy that can, to some degree, mitigate potential negative outcomes from religious education. This argument is further supported with reference to a range of empirical studies.