The complex circumstellar environment of supernova 2023ixf.

The early evolution of a supernova (SN) can reveal information about the environment and the progenitor star. When a star explodes in vacuum, the first photons to escape from its surface appear as a brief, hours-long shock-breakout flare1,2, followed by a cooling phase of emission. However, for stars exploding within a distribution of dense, optically thick circumstellar material (CSM), the first photons escape from the material beyond the stellar edge and the duration of the initial flare can extend to several days, during which the escaping emission indicates photospheric heating3. Early serendipitous observations2,4 that lacked ultraviolet (UV) data were unable to determine whether the early emission is heating or cooling and hence the nature of the early explosion event. Here we report UV spectra of the nearby SN 2023ixf in the galaxy Messier 101 (M101). Using the UV data as well as a comprehensive set of further multiwavelength observations, we temporally resolve the emergence of the explosion shock from a thick medium heated by the SN emission. We derive a reliable bolometric light curve that indicates that the shock breaks out from a dense layer with a radius substantially larger than typical supergiants.

A Monte Carlo model of an industrial gauge for radiation protection purposes.

The Mahlo Gravimat densitometers/gauges located at the Feltex carpet factory in Christchurch, New Zealand, contain the radionuclide strontium-90 (Sr-90). Accurate dose/dose rate estimation is always an important concern from a radiation protection point of view. The EGSnrc/BEAMnrc Monte Carlo code was used to create a model of one gauge to determination of the radiation dose distributions and dose rates in air from the Sr-90 source within the gauge. The model was then modified to include a Perspex shield on the surface of the gauge as a possible method of lowering the radiation levels. With this addition, the model predicted an overall reduction in dose rates of 30%. Although no experimental benchmarking was able to be performed due to simplifications in the model and the lack of reliable experimental data, we believe that Monte Carlo methods could be a valuable addition in the design process of any devices, industrial or otherwise, that contain or use radioactive materials. Furthermore, such methods may aide or guide any investigations undertaken as part of radiation protection surveys.

Individual differences in cognitive planning on the Tower of Hanoi task: neuropsychological maturity or measurement error?

The Tower of Hanoi (ToH) task was given to 238 children aged from 7 to 15 years, and 20 adults. Individual variation within an age band was substantial. ToH score did not correlate significantly with Verbal IQ, nor with ability to inhibit a prepotent response. We readministered the ToH to 45 children after 30 to 40 days. The test-retest correlation of .5 is low in relation to accepted psychometric standards, though at least as high as reliability of the related Tower of London (ToL) in adults. The reasons for low reliability remain unclear: task novelty did not seem to be involved, as children did not improve on retest. We conclude that it is not safe to use this test to index integrity or maturation of underlying neurological systems in children. We compared our results with three published studies using the ToL with children, and found similar levels of performance on problems involving the same number of moves. Another study using automated ToL obtained much poorer scores, suggesting that computerised presentation may impair children's performance.

Prevalence of complementary therapy use by women with breast cancer. A population-based survey.

The study measured the prevalence and costs of complementary therapy use by women diagnosed with breast cancer in the South Thames NHS region. A postal questionnaire was sent to a sample of 1023 women from the Thames Cancer Registry who had been diagnosed with breast cancer in the previous 7 years. Just over a fifth (22.4%) had consulted a complementary practitioner in the previous 12 months. Almost one third (31.5%) had done so since diagnosis. Almost pound17000 had been spent on visits in the previous year. The women using complementary medicine after diagnosis were slightly younger, more educated and more likely to have used complementary medicine before their diagnosis than non-complementary medicine users. In conclusion, significant numbers of women are visiting complementary therapists for health reasons following a breast cancer diagnosis. The out of pocket costs per user, with notable exceptions, are modest. Use of practitioners of complementary therapies following diagnosis is a significant and possibly growing phenomenon.

Evidence from Turner's syndrome of an imprinted X-linked locus affecting cognitive function.

Turner's syndrome is a sporadic disorder of human females in which all or part of one X chromosome is deleted. Intelligence is usually normal but social adjustment problems are common. Here we report a study of 80 females with Turner's syndrome and a single X chromosome, in 55 of which the X was maternally derived (45,X[m]) and in 25 it was of paternal origin (45,X[p]). Members of the 45,X[p] group were significantly better adjusted, with superior verbal and higher-order executive function skills, which mediate social interactions. Our observations suggest that there is a genetic locus for social cognition, which is imprinted and is not expressed from the maternally derived X chromosome. Neuropsychological and molecular investigations of eight females with partial deletions of the short arm of the X chromosome indicate that the putative imprinted locus escapes X-inactivation, and probably lies on Xq or close to the centromere on Xp. If expressed only from the X chromosome of paternal origin, the existence of this locus could explain why 46,XY males (whose single X chromosome is maternal) are more vulnerable to developmental disorders of language and social cognition, such as autism, than are 46,XX females.