Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massive star.

Every supernova so far observed has been considered to be the terminal explosion of a star. Moreover, all supernovae with absorption lines in their spectra show those lines decreasing in velocity over time, as the ejecta expand and thin, revealing slower-moving material that was previously hidden. In addition, every supernova that exhibits the absorption lines of hydrogen has one main light-curve peak, or a plateau in luminosity, lasting approximately 100 days before declining. Here we report observations of iPTF14hls, an event that has spectra identical to a hydrogen-rich core-collapse supernova, but characteristics that differ extensively from those of known supernovae. The light curve has at least five peaks and remains bright for more than 600 days; the absorption lines show little to no decrease in velocity; and the radius of the line-forming region is more than an order of magnitude bigger than the radius of the photosphere derived from the continuum emission. These characteristics are consistent with a shell of several tens of solar masses ejected by the progenitor star at supernova-level energies a few hundred days before a terminal explosion. Another possible eruption was recorded at the same position in 1954. Multiple energetic pre-supernova eruptions are expected to occur in stars of 95 to 130 solar masses, which experience the pulsational pair instability. That model, however, does not account for the continued presence of hydrogen, or the energetics observed here. Another mechanism for the violent ejection of mass in massive stars may be required.

Astrophysics. Multiple images of a highly magnified supernova formed by an early-type cluster galaxy lens.

In 1964, Refsdal hypothesized that a supernova whose light traversed multiple paths around a strong gravitational lens could be used to measure the rate of cosmic expansion. We report the discovery of such a system. In Hubble Space Telescope imaging, we have found four images of a single supernova forming an Einstein cross configuration around a redshift z = 0.54 elliptical galaxy in the MACS J1149.6+2223 cluster. The cluster's gravitational potential also creates multiple images of the z = 1.49 spiral supernova host galaxy, and a future appearance of the supernova elsewhere in the cluster field is expected. The magnifications and staggered arrivals of the supernova images probe the cosmic expansion rate, as well as the distribution of matter in the galaxy and cluster lenses.

Supernova SN 2011fe from an exploding carbon-oxygen white dwarf star.

Type Ia supernovae have been used empirically as 'standard candles' to demonstrate the acceleration of the expansion of the Universe even though fundamental details, such as the nature of their progenitor systems and how the stars explode, remain a mystery. There is consensus that a white dwarf star explodes after accreting matter in a binary system, but the secondary body could be anything from a main-sequence star to a red giant, or even another white dwarf. This uncertainty stems from the fact that no recent type Ia supernova has been discovered close enough to Earth to detect the stars before explosion. Here we report early observations of supernova SN 2011fe in the galaxy M101 at a distance from Earth of 6.4 megaparsecs. We find that the exploding star was probably a carbon-oxygen white dwarf, and from the lack of an early shock we conclude that the companion was probably a main-sequence star. Early spectroscopy shows high-velocity oxygen that slows rapidly, on a timescale of hours, and extensive mixing of newly synthesized intermediate-mass elements in the outermost layers of the supernova. A companion paper uses pre-explosion images to rule out luminous red giants and most helium stars as companions to the progenitor.

An examination of the health and wellbeing of childless women: a cross-sectional exploratory study in Victoria, Australia.

BACKGROUND: Childlessness among Australian women is increasing. Despite this, little is known about the physical and mental health and wellbeing of childless women, particularly during the reproductive years. The aims of this exploratory study were to: 1) describe the physical and mental health and wellbeing and lifestyle behaviours of childless women who are currently within the latter part of their reproductive years (30 - 45 years of age); and 2) compare the physical and mental health and wellbeing and lifestyle behaviours of these childless women to Australian population norms. METHODS: A convenience sample of 50 women aged between 30 and 45 years were recruited to participate in a computer assisted telephone interview. The SF-36 Health Survey v2 and lifestyle indicators were collected in regards to women's health and wellbeing. Data were analysed using descriptive statistics, t-tests for independent sample means and 95% confidence intervals for the difference between two independent proportions. RESULTS: Childless women in this study reported statistically significant poorer general health, vitality, social functioning and mental health when compared to the adult female population of Australia. With the exception of vegetable consumption, lifestyle behaviours were similar for the childless sample compared to the adult female population in Australia. CONCLUSIONS: Childless women may be at a greater risk of experiencing poor physical and mental health when compared to the Australian population. A woman's health and wellbeing during her reproductive years may have longer term health consequences and as such the health and wellbeing of childless women requires further investigation to identify and address implications for the provision of health (and other social) services for this growing population group.

Hysterectomy trends in Australia--between 2000/01 and 2004/05.

BACKGROUND: Hysterectomy is a major and common surgical procedure that has the potential to provide relief from ongoing gynaecological problems, but is often associated with negative impacts on health and wellbeing. Research indicates that hysterectomy rates and trends vary widely between and within countries; yet little is known about patterns in Australia. AIMS: This research aimed to describe hysterectomy rates and trends in Australia between 2000/01 and 2004/05. METHODS: This repeat cross-sectional study used routinely collected data from all hospitals in Australia. Data on all women admitted to hospital for a hysterectomy were obtained from the National Hospital Morbidity Database (2000/01-2004/05). Data were analysed by calculating population rates for each type of hysterectomy. Incidence rate ratios were calculated to assess changes over time. RESULTS: Hysterectomy rates in Australia declined from 34.8 per 10 000 women in 2000/01 to 31.2 per 10 000 women in 2004/05. A decline in the incidence rate for abdominal hysterectomy (from 18.7 to 15.1 per 10 000 women) and the incidence rate for concurrent oophorectomy (from 12.4 to 11.3 per 10 000 women) were also observed during this time period. At each point in time, the highest incidence rates for hysterectomy were for women aged 45-54 years. CONCLUSIONS: Hysterectomy rates in Australia are declining over time and currently appear to be lower than most other countries. More hysterectomies are performed vaginally than in Canada, the USA, the UK and Finland and the rate of concurrent oophorectomy is less than that reported in the USA and the UK.

Rural parents, teenagers and alcohol: what are parents thinking?

INTRODUCTION: The fundamental role of alcohol in the lives of young Australians is mirrored in the level of drinking by adolescents. In 2001, more than one in four Australian adolescents aged 14-19 years consumed alcohol weekly. Teenagers in rural areas are more likely to consume alcohol than their metropolitan counterparts. Parents are key 'gatekeepers' of adolescent behaviour and as such are a salient group to consider in relation to adolescent alcohol use. The aim of this study was to explore parents' attitudes, beliefs, concerns and receptiveness to harm minimisation strategies with respect to teenage use of alcohol. METHODS: A convenience sample of parents with adolescent children attended a series of focus groups across the north and north-western area of the State of Victoria, Australia. Schools were approached to advertise the project and invite parents to participate. Snowball sampling was used to enhance recruitment. RESULTS: Parents described patterns of alcohol use such as 'drinking to get drunk' and the influence of both parents and peers on the consumption of alcohol by adolescents. Few parents were concerned about the long-term risks of alcohol use by teenagers; rather they were more concerned about the short-term harms, for example, road trauma and other accidents and risky behaviours such as binge drinking. Parents indicated that they perceived alcohol to be less harmful than other drugs and many indicated that alcohol was often not perceived to be a drug. A number of strategies were adopted by parents to negotiate teenagers' drinking and to minimise the risks associated with alcohol use. These included transporting teenagers to parties, providing teenagers with a mobile phone, setting clear guidelines about alcohol use and/or providing teenagers with a small amount of alcohol. These were seen by parents as strategies for reducing the risks associated with alcohol consumption. Many parents reported that they do not feel well informed about alcohol use and how and when to use harm reduction strategies. CONCLUSIONS: Rural parents are unsure how to respond to teenagers' alcohol use and drunkenness. While some parental strategies for harm reduction (such as supplying adolescents with a small amount of alcohol) may have good face validity in reducing alcohol consumption among adolescents, these strategies are not supported by previous research findings.

Teaching research and epidemiology to undergraduate students in the health sciences.

OBJECTIVE: To identify and address particular challenges in the teaching of epidemiological concepts to undergraduate students in non-clinical health disciplines. METHODS AND RESULTS: Relevant pedagogical literature was reviewed to identify a range of evidence-based teaching approaches. The authors also drew on their experience in curriculum development and teaching in this field to provide guidelines for teaching epidemiology in a way that is engaging to students and likely to promote deep, rather than surface, learning. Discussion of a range of practical strategies is included along with applied examples of teaching epidemiological content. CONCLUSIONS AND IMPLICATIONS: Increasingly, there is a greater emphasis on improved learning outcomes in higher education. Graduates from non-clinical health courses are required to have a core understanding of epidemiology and teachers of epidemiology need to be able to access resources that are relevant and useful for these students. A theoretically grounded framework for effective teaching of epidemiological principles to non-clinical undergraduates is provided, together with a range of useful teaching resources (both paper and web-based). Implementation of the strategies discussed will help ensure graduates are able to appropriately apply epidemiological skills in their professional practice.