Flood modelling with hydraTE: 2+1-dimensional smoothed-particle hydrodynamics

We present HydraTE, our own implementation of the smoothed-particle hydrodynamics technique for shallow water that uses the adaptive size of the smoothing kernel as a proxy for the local water depth. We derive the equa- tions of motion for this approach from the Lagrangian before demonstrating that we can model the depth of water in a trough, implement vertical walls, recover the correct acceleration and terminal velocity for water flowing down a slope and obtain a stable hydraulic jump with the correct jump condition. We demonstrate that HydraTE performs well on two of the UK Environ- ment Agency flood modelling benchmark tests. Benchmark EA3 involves flow down an incline into a double dip depression and studies the amount of water that reaches the second dip. Our results are in agreement with those of the other codes that have attempted this test. Benchmark EA6 is a dam break into a horizontal channel containing a building. HydraTE again pro- duces results that are in good agreement with the other methods and the experimetal validation data except where the vertical velocity structure of the flow is expected to be multi-valued, such as the hydralic jump where the precise location is not recovered even though the pre- and post- jump water heights are. We conclude that HydraTE is suitable for a wide range of flood modelling problems as it preforms at least as well as the best available commercial alternatives for the problems we have tested

The orientation of galaxy dark matter haloes around cosmic voids

Using the Millennium N-body Simulation we explore how the shape and angular momentum of galaxy dark matter haloes surrounding the largest cosmological voids are oriented. We find that the major and intermediate axes of the haloes tend to lie parallel to the surface of the voids, whereas the minor axis points preferentially in the radial direction. We have quantified the strength of these alignments at different radial distances from the void centres. The effect of these orientations is still detected at distances as large as 2.2 Rvoid from the void centre. Taking a subsample of haloes expected to contain disc-dominated galaxies at their centres we detect, at the 99.9 per cent confidence level, a signal that the angular momentum of those haloes tends to lie parallel to the surface of the voids. Contrary to the alignments of the inertia axes, this signal is only detected in shells at the void surface (1 < R < 1.07 Rvoid) and disappears at larger distances. This signal, together with the similar alignment observed using real spiral galaxies, strongly supports the prediction of the Tidal Torque theory that both dark matter haloes and baryonic matter have acquired, conjointly, their angular momentum before the moment of turnaround

Gravitational waves from fermion production during axion inflation

We present analytic results for the gravitational wave power spectrum induced in models where the inflaton is coupled to a fermionic pseudocurrent. We show that although such a coupling creates helically polarized fermions, the polarized component of the resulting gravitational waves is parametrically suppressed with respect to the non-polarized one. We also show that the amplitude of the gravitational wave signal associated to this production cannot exceed that generated by the standard mechanism of amplification of vacuum fluctuations. We previously found that this model allows for a regime in which the backreaction of the produced fermions allows for slow-roll inflation even for a steep inflaton potential, and still leads to Gaussian primordial scalar perturbations. The present analysis shows that this regime also results in a gravitational wave signal compatible with the current bounds.Comment: 29 pages, 2 figure

The work of a religious representative in a democratic legislature: A case study of the Lord Bishop of Sodor and Man in Tynwald, 1961-2001

The Isle of Man is a largely autonomous territory of the United Kingdom Crown, whose dominant constitutional body is the Tynwald. Tynwald, although meeting regularly as a single body, is for most purposes divided into two Branches – a directly elected House of Keys, and the Legislative Council. The latter includes among its members the Lord Bishop of Sodor and Man. This study draws upon the legislative debates of Tynwald between 1961 and 2001 to examine the nature of the Bishop’s role. Analysis shows that the Bishop was expected to contribute to debate in two major areas – moral issues and technical issues concerning the Manx Church. Additionally, the Bishops operated within expectations as to their modes of contribution. The strongest of these was that the Bishop should not become entangled in party politics. There was also a strong expectation that the Bishop should represent the Manx Church and Christianity more generally, although this expectation does not seem to have been realised in relation to non-Christian religions. There is also evidence that the Bishop was also entitled to use both secular and religious modes of argumentation, and that he should not have expected to the be the only religious voice in Tynwald, or even the uncontested voice of the Manx Church

Organic farming: technology transfer (Environmental impact and soil fertility) (OF0405)

This project covered two separate activities, but both were examples of technology transfer, relating to organic farming: 1. Developing a science-based report, which covered an assessment of the environmental impacts of organic farming. Defra’s Action Plan to Develop Organic Food and Farming included as Annexe 3 an assessment of the environmental impacts of organic farming. This paper was prepared by a Subgroup of the Action Plan for Organic Farming. Its purpose was to summarise the Subgroup’s views of the likely comparative effects of organic and conventional farming on the environment. However, to be robust and defensible, the assessment needs to be supported by scientific data. Although the report was based on such an assessment, the scientific data were not summarised and this needed to be done. The objective of this part of the project was therefore to collate and publish on the Defra website the evidence that underpinned the overall conclusions. 2. Preparation of a booklet to provide guidelines for managing soil fertility in organic farming. Organic farming aims to create an economically and environmentally sustainable agriculture, with the emphasis placed on self-sustaining biological systems, rather than external inputs. Building soil fertility is central to this ethos. ‘Soil fertility’ can be considered as a measure of the soil’s ability to sustain satisfactory crop growth, both in the short- and longer-term, and it is determined by a set of interactions between the soil’s physical environment, chemical environment and biological activity. The aim of recent Defra-funded projects has been, therefore, to provide a better scientific understanding of ‘soil fertility’ under organic farming, in line with Defra’s policy objective of greater technical support to organic farming. The aim here was to prepare a booklet based on the findings of Defra-funded project OF0164 ‘Soil fertility in organically farmed soils’

Baring Their Souls in Online Profiles or Not? Religious Self-Disclosure in Social Media

This study measured the prevalence of religious self-disclosure in public MySpace profiles that belonged to a subsample of National Study of Youth and Religion (NSYR) wave 3 respondents (N=560). Personal attributes associated with religious identification as well as the overall quantity of religious self-disclosures are examined. A majority (62 percent) of profile owners identified their religious affiliations online, although relatively few profile owners (30 percent) said anything about religion outside the religion-designated field. Most affiliation reports (80 percent) were consistent with the profile owner’s reported affiliation on the survey. Religious profile owners disclosed more about religion when they also believed that religion is a public matter or if they evaluated organized religion positively. Evangelical Protestants said more about religion than other respondents. Religiosity, believing that religion is a public matter, and the religiosity of profile owners’ friendship group were all positively associated with religious identification and self-disclosure

Streams Going Notts: The tidal debris finder comparison project

While various codes exist to systematically and robustly find haloes and subhaloes in cosmological simulations (Knebe et al., 2011, Onions et al., 2012), this is the first work to introduce and rigorously test codes that find tidal debris (streams and other unbound substructure) in fully cosmological simulations of structure formation. We use one tracking and three non-tracking codes to identify substructure (bound and unbound) in a Milky Way type simulation from the Aquarius suite (Springel et al., 2008) and post-process their output with a common pipeline to determine the properties of these substructures in a uniform way. By using output from a fully cosmological simulation, we also take a step beyond previous studies of tidal debris that have used simple toy models. We find that both tracking and non-tracking codes agree well on the identification of subhaloes and more importantly, the {\em unbound tidal features} associated with them. The distributions of basic properties of the total substructure distribution (mass, velocity dispersion, position) are recovered with a scatter of $\sim20$. Using the tracking code as our reference, we show that the non-tracking codes identify complex tidal debris with purities of $\sim40$. Analysing the results of the substructure finders, we find that the general distribution of {\em substructures} differ significantly from the distribution of bound {\em subhaloes}. Most importantly, both bound and unbound {\em substructures} together constitute $\sim18$ of the host halo mass, which is a factor of $\sim2$ higher than the fraction in self-bound {\em subhaloes}. However, this result is restricted by the remaining challenge to cleanly define when an unbound structure has become part of the host halo. Nevertheless, the more general substructure distribution provides a more complete picture of a halo's accretion history.Comment: 19 pages, 12 figures, accepted for publication in MNRA