Solving Decision Problems with Limited Information

We present a new algorithm for exactly solving decision-making problems represented as an influence diagram. We do not require the usual assumptions of no forgetting and regularity, which allows us to solve problems with limited information. The algorithm, which implements a sophisticated variable elimination procedure, is empirically shown to outperform a state-of-the-art algorithm in randomly generated problems of up to 150 variables and 10^64 strategies.

The VLT-FLAMES Tarantula survey: XX. The nature of the X-ray bright emission-line star VFTS 399

Context: The stellar population of the 30 Doradus star-forming region in the Large Magellanic Cloud contains a subset of apparently single, rapidly rotating O-type stars. The physical processes leading to the formation of this cohort are currently uncertain. 

Aims: One member of this group, the late O-type star VFTS 399, is found to be unexpectedly X-ray bright for its bolometric luminosity-in this study we aim to determine its physical nature and the cause of this behaviour. 

Methods: To accomplish this we performed a time-resolved analysis of optical, infrared and X-ray observations. 

Results: We found VFTS 399 to be an aperiodic photometric variable with an apparent near-IR excess. Its optical spectrum demonstrates complex emission profiles in the lower Balmer series and select He i lines-taken together these suggest an OeBe classification. The highly variable X-ray luminosity is too great to be produced by a single star, while the hard, non-thermal nature suggests the presence of an accreting relativistic companion. Finally, the detection of periodic modulation of the X-ray lightcurve is most naturally explained under the assumption that the accretor is a neutron star. 

Conclusions: VFTS 399 appears to be the first high-mass X-ray binary identified within 30 Dor, sharing many observational characteristics with classical Be X-ray binaries. Comparison of the current properties of VFTS 399 to binary-evolution models suggests a progenitor mass 25 M_⊙ for the putative neutron star, which may host a magnetic field comparable in strength to those of magnetars. VFTS 399 is now the second member of the cohort of rapidly rotating "single" O-type stars in 30 Dor to show evidence of binary interaction resulting in spin-up, suggesting that this may be a viable evolutionary pathway for the formation of a subset of this stellar population.

"It's just not cricket". Or is it?

Considers the Wolverhampton County Court decision in Bartlett v English Cricket Board Association of Cricket Officials on whether cricket umpires at an amateur match were liable for injuries to a player based on their inspection of the condition of the cricket ground after heavy rain and their decision to allow play to proceed. Comments on the approach to the umpires' standard of care.

"IT'S JUST NOT CRICKET": ANALYZING SPORTS NEGLIGENCE IN THE UK

This presentation is about the law of professional negligence as it applies to sport. The presentation asks, paradoxically, if the skills you have as a sports coach or official might ever, on not being reasonably applied, leave you or your sport vulnerable to a claim in negligence. To inform this debate, the recent judgment in Bartlett v English Cricket Board Association of Cricket Officials (unreported, County Court (Birmingham), 27 August 2015) is critically considered. Arguably, this case is indicative of the extension of tortious liability in the UK, most notably, for officials and coaches in the context of amateur sport, essentially requiring HHJ Lopez to determine what might be termed the ‘professional liability of an amateur’.