The problem of misdeclared container weight

This paper addresses the problem of misdeclaring container weights, which causes accidents on land and sea, with serious consequences. It reviews the current international and New Zealand domestic law, and the plan to mandate verification of container weight in the Safety of Life at Sea (SOLAS) convention. It concludes that this is unlikely to be enough by itself to fix the problem. It considers the points in the supply chain where responsibility could be placed for weighing, and proposes a “chain of responsibility” approach with initial weighing by the shipper and check weighing later, especially at ports, with misdeclared containers being reportable as incidents. Such a system should rid New Zealand of the problem

Long time-scale variability in GRS1915+105

We present very high resolution hydrodynamical simulations of accretion discs in black hole X-ray binaries accreting near the Eddington limit. The results show that mass loss, irradiation and tidal interactions all have a profound effect on the observed behaviour of long period X-ray transients. In particular, the interplay of all of these effects in the outer regions of the accretion disc is able to drive long time-scale (weeks to years) variability is these objects, and is a possible origin for some of the extreme variability of GRS1915+105.Comment: 7 pages, 9 figures (2 in colour), accepted for publication in MNRA

Clearing Out a Galaxy

It is widely suspected that AGN activity ultimately sweeps galaxies clear of their gas. We work out the observable properties required to achieve this. Large-scale AGN-driven outflows should have kinetic luminosities $\sim \eta\le/2 \sim 0.05\le$ and momentum rates $\sim 20\le/c$, where $\le$ is the Eddington luminosity of the central black hole and $\eta\sim 0.1$ its radiative accretion efficiency. This creates an expanding two-phase medium in which molecular species coexist with hot gas, which can persist after the central AGN has switched off. This picture predicts outflow velocities $\sim 1000 - 1500$ km\,s$^{-1}$ and mass outflow rates up to 4000 \msun\,{\rm yr}^{-1} on kpc scales, fixed mainly by the host galaxy velocity dispersion (or equivalently black hole mass). All these features agree with those of outflows observed in galaxies such as Mrk231. This strongly suggests that AGN activity is what sweeps galaxies clear of their gas on a dynamical timescale and makes them red and dead. We suggest future observational tests of this picture.Comment: 6 pages, 1 figure, 2 tables; accepted for publication in ApJ Letter

Does the Health and Safety at Work Act 2015 Apply to Roads?

This article examines how far the Health and Safety at Work Act 2015 applies to roads. Road authorities have substantial control over the safe use of their roads and, as roads are a product of work, it might be expected that the Act applies to any deficiencies in that work that create harm, as it does to most areas of the economy. But the Act can be read in a way that limits its applicability to actions that cause harm much later and indeed to public safety in general. The article analyses some key sections of the Act to see how far their duties might extend to road authorities. It concludes that while there is some room for doubt, the Act is capable of supporting a prosecution of a road authority, especially in relation to a work-use vehicle. In addition, the so-called "upstream duties" on designers and others could well create a liability for the authorities. The article nevertheless proposes reforms to clarify the liability

Magnetically warped discs in close binaries

We demonstrate that measurable vertical structure can be excited in the accretion disc of a close binary system by a dipolar magnetic field centred on the secondary star. We present the first high resolution hydrodynamic simulations to show the initial development of a uniform warp in a tidally truncated accretion disc. The warp precesses retrogradely with respect to the inertial frame. The amplitude depends on the phase of the warp with respect to the binary frame. A warped disc is the best available explanation for negative superhumps.Comment: 11 pages, 10 figures, MNRAS accepte

Superhumps in Low-Mass X-Ray Binaries

We propose a mechanism for the superhump modulations observed in optical photometry of at least two black hole X-ray transients (SXTs). As in extreme mass-ratio cataclysmic variables (CVs), superhumps are assumed to result from the presence of the 3:1 orbital resonance in the accretion disc. This causes the disc to become non-axisymmetric and precess. However the mechanism for superhump luminosity variations in low mass X-ray binaries (LMXBs) must differ from that in CVs, where it is attributed to a tidally-driven modulation of the disc's viscous dissipation, varying on the beat between the orbital and disc precession period. By contrast in LMXBs, tidal dissipation in the outer accretion disc is negligible: the optical emission is overwhelming dominated by reprocessing of intercepted central X-rays. Thus a different origin for the superhump modulation is required. Recent observations and numerical simulations indicate that in an extreme mass-ratio system the disc area changes on the superhump period. We deduce that the superhumps observed in SXTs arise from a modulation of the reprocessed flux by the changing area. Therefore, unlike the situation in CVs, where the superhump amplitude is inclination-independent, superhumps should be best seen in low-inclination LMXBs, whereas an orbital modulation from the heated face of the secondary star should be more prominent at high inclinations. Modulation at the disc precession period (10s of days) may indicate disc asymmetries such as warping. We comment on the orbital period determinations of LMXBs, and the possibility and significance of possible permanent superhump LMXBs.Comment: 6 pages, 1 encapsulated figure. MNRAS in press; replaced to correct typographical error

The Existence of Sterile Neutrino Halos in Galactic Centers as an Explanation of the Black Hole mass - Velocity Dispersion Relation

If sterile neutrinos exist and form halos in galactic centers, they can give rise to observational consequences. In particular, the sterile neutrinos decay radiatively and heat up the gas in the protogalaxy to achieve hydrostatic equilibrium, and they provide the mass to form supermassive blackholes. A natural correlation between the blackhole mass and velocity dispersion thus arises $\log(M_{BH,f}/M_{\odot})=\alpha \log (\sigma /200 {\rm km s^{-1}})+ \beta$ with $\alpha \approx 4$ and $\beta \approx 8$.Comment: Accepted in Ap

Rethinking Human Security

Governmen